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1
Jullion, Loĭc. "Water mass modification in the southwestern Atlantic." Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446168.
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Moran, Paul Aaron. "Modification of a Biosand Water Filter for Household Treatment of High Turbidity Water." Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-theses/752.
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One billion of the poorest people in the world today do not have access to improved drinking water. Without treatment, fecal contamination results in an overwhelming disease burden. A long term best practice solution will take decades to implement. In the meantime, approximately 5 million children under five die each year from gastrointestinal diseases. This tragedy can be alleviated by household water treatment. Household Water Treatment and safe Storage systems (HWTS) provide an interim solution. While many low cost and simple technologies exist, none of them are effective against high suspended solids concentrations (>50 NTU). Previous short-term field research by others has considered modifying a BioSand water Filter (BSF), to include pretreatment through an upper sand layer in order to extend the run cycle of the primary filter, enabling complete ripening to occur. In this research program, one control and twelve configurations of modified filters were setup in the laboratory. Water was chemically conditioned to provide worst case scenario treatment by adjusting pH, TDS, and particle dispersion. Sample water was passed through each filter daily, and monitored for DO, turbidity, flow rate, and E. coli concentrations. The results indicate that pretreatment is not necessarily beneficial under all water quality conditions. Recommendations include a description of conditions under which the modification may be beneficial, and optimized pretreatment design criteria. Regardless of water quality conditions, it was found that changing the operational guidelines for filter use can significantly improve treatment efficiency, without complicating the filter design. Design guidelines for an unmodified filter coupled with operational guidelines are provided, in order to obtain sufficient quantities of the best possible water quality under high turbidity conditions. This will enable the BSF to be used in high turbidity conditions and still significantly improve the drinking water quality. It is hoped that this will decrease the disease burden and loss of life in many of the world's poorest communities.
3
Brandon, Mark Alan. "Winter surface water mass modification in the Greenland Sea." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388764.
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4
Oztekin, Tekin. "Modification and evaluation of WEPP water table management model /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488196234908385.
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5
Gargiuli, Joseph Fernand. "Synthesis and modification of water-soluble hyperbranched poly(amidoamine)s." Thesis, Durham University, 2002. http://etheses.dur.ac.uk/3871/.
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The multi-step syntheses of two water-soluble AB(_2) monomers, N-acryloyl-1,2- diaminoethane hydrochloride and N-acryloyl-1,2-daminoethane, are reported. The melt polymerisation at 210 ºC for 4 hours of N-acryloyl-1,2-diaminoethane hydrochloride gave, by Michael additions of the terminal ammonium salts (B(_2) groups) of a monomer molecule or growing oligomer with the unreacted vinyl double bond (A group) of another monomer molecule or growing oligomer, hyperbranched macromolecules. High degrees of conversion, determined using (^1)H NMR spectroscopy, were obtained and a degree of branching, determined using (^15)N NMR spectroscopy, was found to be equal or close to 1. However, this method proved difficult to reproduce and the alternative aqueous solution polymerisation at 100 ºC for 10 days of this monomer was investigated. The use of ampoules closed with Teflon taps as reactors lead to polymers displaying random signs of free radical polymerisation and high degrees of conversion due to such side-reaction, whereas, the alternative use of sealed Carius tubes lead to lower DP materials displaying no significant signs of free radical side-reactions. The kinetic study of this polymerisation allowed the determination of the rate constant associated with the oligomer growth and the MALDI analysis of these polymers revealed an evolution with time of the oligomer molecular weight distribution with time in agreement with the theoretical prediction. This last study also revealed that at least 70% of the molecules were not cyclised. On the other hand, the aqueous solution polymerisation of the corresponding free base monomer, N-acryloyl-1,2- diaminoethane, at 100 ºC for 90 minutes lead to hyperbranched macromolecules with high DP values. The kinetic study did not allow a precise determination of the rate constant associated with the oligomer growth due to the high reactivity of the free terminal amino groups. The MALDI analysis of these polymer samples showed that the evolution with time of the oligomer molecular weight distribution did not follow the theoretical prediction and that these macromolecules were cyclised.
6
Villanoy, Cesar Laurel. "Modification of the throughflow water properties in the Indonesian seas." Thesis, The University of Sydney, 1993. https://hdl.handle.net/2123/26591.
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Vertical mixing in the Indonesian Seas has been considered to be responsible for the apparent freshness of the throughflow when 'it enters the Indian Down. A three-dimensional primitive equation numerical model of the Indonesian Seas forced with a prescribed throughflow, transport consisting of North Pacific waters, is used to determine local dynamic processes which may modify the characteristics of the throughflow properties. The lack of long-term current measurements in the Indonesian Seas presents some difficulties in determining the certainty of the derived velocity fields. As an alternative, the model temperature and salinity fields are compared to observed hydrographic data which has a relatively better coverage throughout the Indonesian Seas. A 15 Sv net transport through the Indonesian Seas is suggested based on the model’s more realistic reproduction of the hydrographic structure compared to a throughflow with a smaller magnitude. A pure North Pacific source for the throughflow is also not capable of producing the salinity structure in the Banda Sea as suggested by previous studies and the required amount of salt to fit the model salinity structure with observations in the Banda Sea is estimated to be 3.3x10‘3 kg.
Most of the throughflow transport occurs in western boundary flows and is largely topographically controlled. The separation of an upper and lower layer circulation pattern is controlled by the depth of the sill in Makassar Strait. Vertical excursions in the vicinity of this sill seen level of the in model results coincide upper salinity maximum with regions where are found. Seasonal large horizontal gradients at the upwelling and longer residence times due to weaker flows in the Banda Sea results in a more effective mixing of the already weakened salinity structure of the waters from Makassar Strait/Flores Sea. Net heat and freshwater flux estimates also reveal significant departures at 200 up to 100 m between the Pacific inflow and Indian outflow, suggesting the considerable redistribution of heat and salt in the Indonesian Seas.
7
Grow, David E. "Fractal Modification of Tree-Ring Chronologies for Discharge Reconstructions." Arizona-Nevada Academy of Science, 2003. http://hdl.handle.net/10150/296606.
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8
Mawhinney, Heather Joan. "The improvement of effluent and water treatment by chemical floc modification." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343019.
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9
DALLE, CARBONARE Nicola. "Surface and interface modification of nanostructured hematite for solar water splitting." Doctoral thesis, Università degli studi di Ferrara, 2016. http://hdl.handle.net/11392/2403264.
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La possibilità di produrre idrogeno dalla scissione fotoindotta dell’acqua imitando
ciò che la natura fa in ogni istante attraverso la fotosintesi, senza la necessità quindi di
utilizzare alcuna fonte aggiuntiva di energia esterna, ha suscitato enorme interesse nella
comunità scientifica, stimolata dal sogno di poter sviluppare una società che utilizzi
idrogeno come fonte energetica primaria. Negli ultimi quattro decenni abbiamo assistito
ad una straordinaria accelerazione nella razionalizzazione delle proprietà chimico-fisiche
di materiali semiconduttori su cui si basano sistemi foto-elettrochimici adibiti alla
conversione della luce solare in energia chimica e non in corrente elettrica da utilizzare
istantaneamente, come nei comuni dispositivi fotovoltaici. Sin dai primi esperimenti di
fotolisi, gli ossidi metallici sono stati i protagonisti di tali dispostivi, grazie alla loro
eccellente stabilità in soluzioni acquose e alla possibilità di ottenere facilmente
morfologie nano-strutturate che hanno garantito un notevole incremento in termini di
assorbimento della radiazione luminosa e di capacità catalitiche nei confronti delle
reazioni di riduzione ed ossidazione dell’acqua. Nel corso del mio Dottorato di Ricerca ho
studiato le dinamiche di trasferimento di carica di elettrodi di ossido ferrico modificati
con strutture sia amorfe che cristalline a base di ferro utilizzando, per la caratterizzazione,
principalmente tecniche elettrochimiche sia in corrente continua che alternata, affiancate
da spettroscopie di superficie e laser per una completa descrizione delle proprietà
catalitiche. L’ossido ferrico è un materiale notoriamente impiegato per la foto-ossidazione
dell’acqua, anche se la sua scarsa capacità di condurre e trasferire carica richiedono
l’applicazione di un potenziale esterno. Utilizzando materiali non nocivi ed economici e
semplici procedure in soluzione per la preparazione dei campioni e per le successive
modifiche, siamo stati in grado di migliorare le prestazioni degli elettrodi sia in termini di
foto-correnti generate che di stabilità, razionalizzando al contempo aspetti meccanicistici
coinvolti nei processi di trasferimento di carica responsabili dell’ossidazione dell’acqua.<br>Inspired by nature and pursuing the concrete option of an economy based on
hydrogen as a fuel for the everyday energetic consumption, scientists from different
fields have based their research activity on the possibility to decompose water in its
elementary constituents using only sunlight as external energy supply. In the last four
decades there has been an exciting growth of knowledge about semiconductor physico
chemical properties with regard to their leading role in photo-electrochemical (PEC)
device able to convert light into chemical energy stored in the bond between hydrogen
atoms, in a more elegant and powerful way with respect to conventional photovoltaic
technology. Metal oxides have been from the beginning the most examined materials for
PEC application due to their great stability in aqueous solution and to the easy access to
various nanostructured morphologies that guarantee good optical and catalytic
properties. During my PhD I have investigated the charge transfer dynamics in hematite
(α-Fe2O3) thin film electrodes modified with iron oxide-based structures by using mainly
both AC/DC electrochemical techniques in combination with laser photolysis and
spectroscopy for the morphological characterization. Hematite is a well known
semiconductor able to drive the bias-assisted water oxidation reaction at its surface,
although important drawbacks related to its poor charge transport properties have
limited the overall efficiency achieved so far. Using cheap and environmentally safe
starting materials and solution-based procedure for all the preparative and modification
steps, we have been able to efficiently modify mesoporous iron oxide films achieving
excellent performances in term of photocurrent generation and stability. Mechanistic and
kinetic insights about the effect of an iron-based water oxidation catalyst and of a thin
underlayer are fundamental to a deeper understanding of the photogenerated carriers
fate for a more useful design of these electrodes. Besides electrochemical performance,
the possibility to obtain efficient devices with common and simple procedures is a key
point for a future and concrete implementation of this technology for a large scale
application.
10
Bauer, Elizabeth Nanette. "MODIFICATION OF AN EXISTING BENTHAL MODEL FOR PAPER MILL WASTES." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275443.
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Benavente, Lucia. "Low fouling membranes for water and bio tech applications." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30213/document.
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La pénurie d'eau est devenue un des problèmes clés à résoudre, et pour y faire face, il est nécessaire de disposer d'unités de traitement de l'eau efficaces. Au cours des dernières décennies la technologie des membranes est devenue l'une des techniques les plus prometteuses pour le traitement de l'eau. Néanmoins, les membranes ont une durée de vie limitée et sont, par ailleurs, sujettes à des phénomènes de colmatage - le dépôt, l'adsorption et l'absorption de particules dans la structure de la membrane -, ce qui réduit leur productivité, et augmente les coûts opérationnels. Une approche pour minimiser ce problème consiste à modifier des membranes hydrophobes, mécaniquement et chimiquement stables, en y greffant des matériaux amphiphiles afin de réduire le colmatage. L'objectif principal de ce travail est de caractériser les propriétés anti-colmatage des membranes de PVDF (Polyvinylidene fluoride) modifiées avec différents types de copolymères PS-PEGMA (Polystyrene - Poly(ethylene glycol) methacrylate), tout d'abord par l'utilisation de techniques classiques, puis, par le développement et / ou l'adaptation de techniques microfluidiques couplés à la microscopie à fluorescence et l'utilisation de la cartographie par microspectroscopie infrarouge à transformée de Fourier (IRTF). La cartographie IRTF a permis de quantifier localement le greffage et de mettre en évidence l'hétérogénéité du greffage sur la membrane. Ces cartes, représentant l'importance du greffage sur la membrane, ont par ailleurs été corrélées au dépôt de protéines sur la surface. Des systèmes microfluidiques ont également été développés pour caractériser sous microscope à fluorescence l'adsorption de protéines fluorescentes sur une membrane en présence d'un débit. Cette étude permet de suivre in situ et en dynamique l'adsorption (lors de cycles de filtration) et la désorption (lors de cycles de rinçage) de protéines sur la membrane. Ces mesures locales ont été mises en regard avec des mesures de permeabilité lors de cycles filtrations/rinçage mettant en évidence un rôle anti-fouling en particulier pour les copolymères tri-blocs ou pour les copolymères à enchaînement aléatoire<br>Water scarcity has become one of the key issues to solve, and efficient water treatment is paramount to treat water sources. In recent decades membrane technology has become one of the promising solutions for water treatment. Nevertheless, membranes are prone to fouling phenomena - the deposition, adsorption, and absorption of particles in the membrane structure -, which hinders their life-span and productivity, and raise operative costs. One approach to minimize this issue is to modify the already mechanically and chemically stable hydrophobic membranes with amphiphilic materials. The main aim of this work is to characterise the anti-fouling properties of PVDF (Polyvinylidene fluoride) membranes modified with different types of PS-PEGMA (Polystyrene - Poly(ethylene glycol) methacrylate) copolymers, firstly by using classical techniques, and then, by developing and/or adapting new ones: microfluidic devices coupled with fluorescence microscopy, and the use of Fourier Transform Infrared microspectroscopy (FTIR mapping). FTIR mapping allowed the local detection of the coating layer and showed its heterogeneous distribution on the surface of the membrane. These maps, that represent the importance of the coating on the membrane, were correlated with the deposit of proteins on the surface. Microfluidic systems were also developed to characterise the adsorption of fluorescent proteins on the membrane under a fluorescent microscope in the presence of a flow. This study allowed the in-situ and dynamic follow-up of the adsorption - during filtration cycles - and of the desorption - during rinsing cycles - of the proteins on the membrane. These local measurements were compared against permeability measurements during the filtration/rinsing cycles evidencing the anti-fouling role of the copolymers used for the modification of the membranes, particularly for the triblock and random copolymers
12
Ren, Hanlong. "Modification and Characterization of Ordered Mesoporous Carbons for Resorcinol Removal." Thesis, University of Louisiana at Lafayette, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1585869.
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<p> Ordered mesoporous carbon (OMC) materials have attracted great interests from NASA due to their remarkable properties, such as high specific surface area, regular and tunable pore size. These features show great potential for being used in the water recovery system (WRS) in the International Space Station (ISS) as potential adsorbents. Various methods have been explored on the OMC preparation and modification to achieve better adsorption results. In this research, acrylic acid was used as a carbon precursor to synthesize OMC using a common silica mesoporous template (SBA-15). The influence of silica template amount was tested by using different ratios of SBA-15 to acrylic acid. The modification processes were conducted by immersing methods using four different aqueous solutions: 30% ammonium hydroxide, 0.1% sodium hydroxide, 1 mol/L aluminum chloride, and 0.02 g/mL urea solution. BET-SSA, FT-IR, TEM, TGA, and XRD were used to characterize the structures of OMCs and modified OMCs. It demonstrated that all the products had well-ordered hexagonal structure. The modifying procedures had eroded the surface of the OMC, but the highly ordered structures had been preserved based on the TEM and XRD results. FT-IR analysis indicated that the functional groups were introduced to the surface of the modified OMCs, which affected the adsorption capacity significantly. Resorcinol, a typical total organic carbon (TOC) model compound, was selected to evaluate the adsorption behavior of the OMCs and modified OMCs. Adsorption study illustrates that OMC produced by 3:1 ratio of SBA-15 to acrylic acid showed a higher adsorption capacity than that of OMCs produced with other ratios. The ammonium hydroxide modified OMC had the highest adsorption capacity of 40.6 mg/g for resorcinol removal, compared with that of the other three modified OMCs.</p>
13
Nyandega, Dan, Nigel Bertram, and Morgan L. Thomas. "Cycles of Water and Land : Water sensitive design tactics for highly modified lowlands of coastal cities." Thesis, Monash University, 2019.
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The study investigates highly modified lowlands - the intersection of water and land in coastal cities and their role as 'early warning territories' for the threat of rising water levels. They are concurrently and problematically, important zones for contemporary urban growth and re-development. The study develops alternative water sensitive design tactics, provoked by incremental modification of topographies and water infrastructure to adjust the lowlands to combined pressures of sea-level rise and urban growth in urbanised lowlands of coastal cities.
14
Adamu, Haruna. "Modification of nanotitanium dioxide for enhanced photocatalytic remediation of pollutants in aqueous environments." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=230101.
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Titanium oxide has found different applications in environmental pollution remediation through its use as a photocatalyst for the purification of air and water. However, despite many advantages of TiO2, its use in unmodified form for photocatalytic reactions is hampered by a number of inherent physicochemical properties. The research in this thesis shows that TiO2 containing either copper (Cu) alone or combined copper-activated carbon (Cu-AC) are active in the simultaneous photocatalytic remediation of nitrate and oxalic acid, while pure titania and titania-activated carbon (TiO2/AC) composites found inactive for the reaction. In the case of photocatalytic removal of phenol, titania-thermally reduced graphene oxide (TiO2-TGO) exhibited superior photocatalytic performance than titania-graphene oxide (TiO2-GO) and pure TiO2.
15
Craster, Bernadette. "Studies of the modification of ion and water movement through clays and shales." Thesis, Sheffield Hallam University, 1999. http://shura.shu.ac.uk/19509/.
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-20 m2 and the permeabilitycould be altered with the addition of different additives. Full analysis of the changes in permeability could be performed after a test time of one week compared with a test time of several months in a shale core experiment using the Hassler cell.
16
Davoodi, Amir. "Modification of Water Uptake Capacity of Wood Using Colloidal Solution by Impregnation Technique." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41172.
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Hygroscopic properties are important characteristics of a material that is used in building
construction. Wood is an anisotropic, heterogeneous and hygroscopic material. Given the
cellular structure of wood as well as capillary action in the Lumina, the level of water uptake
in wood is significant.
Such amount of water uptake makes the wood susceptible to dimensional instabilities, causes
alterations in the mechanical properties, and potential for degradation of the material. Various
approaches have been investigated to modify the hydrophilic nature of lignocellulosic
materials, including surface modifications using silane treatments, acetylation, wax etc.
Although these surface modifications can decrease the rate of water uptake by the materials,
the amount of water uptake at saturation remains unchanged. In fact, the lumen diameter is so
small that the rise of liquid, even with a hydrophobic surface, can still occur. Therefore, the
only way to halt the water uptake driven by capillary action in lignocellulosic materials is to
apply a uniform cover on the material surface in addition to filling the lumen with dense
material.
In the current research project, the vascular structure of softwood (Spruce) is obstructed by
silica nanoparticles using the impregnation technique as one of the advanced methods to
reduce the water absorption capacity in wood. This process can form a thin film of
nanoparticles on solid objects with complex geometries. In addition, the technique can fill up
the cavities and voids of porous materials and prevent the capillary action inside the Lumina.
In this method, the wood specimen is dipped into the solution, silica 40 (wt. %) colloidal
solution. Then the solvent is evaporated which results in the formation of nanoparticles in
the form of thin films or particulates. The former may change the moisture absorption on the
surface and the later reduces the capillarity of the vascular system. This project aims to find
the optimal impregnation condition to minimize the water uptake capacity of wood in order to
increase wood physical and mechanical stabilities.
Three immersing times (i.e. short, medium, and long) were used to coat wooden samples with
the silica colloidal solution. The samples were conditioned in wet environments with specificiii
relative time and then their weight as percentage change were examined. To investigate the
capability of the method to obstruct the vascular structure of the wood samples, the
characteristic process was done in the next step by some common tests such as X-ray
Diffraction (XRD), Scanning Electron Microscope (SEM), Water Contact Angle (WCA), etc.
The results from the experiments show that dip-coating the wood samples with silica
nanoparticle colloidal solution had effect on the amount of water absorption, but significant
levels of reduction in water attraction was achieved with considering the other effective
parameters such as duration of each set, the number of sets that are conducted, and
impregnation in vacuumed condition. More research is needed to quantify the benefits of using
nanoparticle in these applications.
17
McKendry, Ian George. "THE SYNTHESIS AND MODIFICATION OF 2D MATERIALS FOR APPLICATION IN WATER OXIDATION CATALYSIS." Diss., Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/439189.
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Chemistry<br>Ph.D.<br>The unifying goal of this work is the design of a heterogeneous catalyst that can facilitate the energy intensive oxygen evolution reaction (OER) in water splitting, considered one of the ‘holy grails’ in catalytic science. In order for this process to be industrially feasible, an efficient catalyst composed of first row transition metal based materials must be used. To accomplish this, existing systems must be studied in order to determine which properties are important and subsequent creation and modification of new systems based on lessons learned must be employed. Birnessite, a 2D layered manganese dioxide, comprises the majority of the effort. In the studies leading to this work, this material was primarily studied by mineralogists with the majority focusing on structural characterization. However, the material’s moderate activity toward performing the OER has revived interest. In this work, we look to determine important species, the role dopants play in activity, and the function of the interlayer and surface chemistry. From these findings, an enhanced, earth abundant OER catalyst will be designed. We determine that Mn3+ in the system plays and important role in producing a catalytic species with large oxygen production capabilities. By increasing the amount of Mn3+ in the system via a simple comproportionation reaction by exposing the Mn4+ to Mn2+ ion, we increase the total turnover of birnessite 50-fold. Additionally, the addition of dopants to the system , both within and between the sheets, has a positive effect on the activity of birnessite. In particular, incorporation of cobalt into the lattice of birnessite brings the activity level on par to that of precious metal oxide catalysts due to the cobalt offering a deeper electron acceptor than in birnessite alone. In conjunction with these studies, the role of the interlayer species and catalyst confinement has demonstrated the ability to greatly enhance a catalyst’s ability to perform the OER by ordering and orienting the water around the active confined catalyst. Combining confinement effects with the cobalt-doped birnessite sheets resulted in further enhancement in the material’s OER capabilities. This system mimics that of an enzyme where the cobalt-doped birnessite sheets facilitate greater electron-hole transfer to the interlayer active site, where the confinement effects enhance electron transfer kinetics and water organization for O-O bond formation. Additionally, metal chalcogenide OER catalysts were explored with mattagamite phase cobalt pertelluride. Through the work, we determine the formation of a Te-Co-O heterostructure as the catalytically active phase, where the metallic nature of the cobalt pertelluride facilitates charge mobility between the electrode and catalyst’s cobalt oxide surface functioning as the active OER species.<br>Temple University--Theses
18
Al-Shajalee, Faaiz Hadi Rasheed. "Relative Permeability Modification in Gas Wells with Excessive Water Production- An Experimental Investigation." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/89365.
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Polymers have been used as relative permeability modifiers (RPM) to selectively reduce water production with minimum effect on the hydrocarbon phase. The experimental results show that initial rock permeability can be used as an important screening parameter in planning an RPM treatment. The relative pore size alteration due to the RPM treatment impacts on RPM performance. The RPM performance is also significantly fluid flow rate dependent. Therefore, flow rate should be considered during RPM design.
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Moses, Alvira. "Synthesis of surface active alkanes for cellulose modification." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/4874.
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119 leaves single sided printed, preliminary pages and numbered pages 1-101. Includes bibliography and a list of tables, figures, schemes and abbreviations. Digitized at 300 dpi (OCR), used Bizhub 250.<br>Thesis (MSc (Polymer Science))--University of Stellenbosch, 2006.<br>ENGLISH ABSTRACT: The properties and interactions of cellulose surfaces are of a great technical interest
during papermaking and recycling. Sizing, the modification of fiber surfaces, e.g. with
the purpose to reduce water penetration into the paper structure, plays an important role
in obtaining paper with good printability and water resistance. Water resistance is the key
end-property of paper being investigated in this study.
Firstly a comparison was made between the degree of surface modification of cellulose
by means of anionic, nonionic and reactive surfactants. The amount of surfactant
adsorbed by the paperboard was determined and the paper surface evaluated via scanning
electron microscopy (SEM). The sizing efficiency of the three industrial surfactants was
evaluated in order to establish the surfactant structure best suited for sizing recycled
paperboard. This was done via the Cobb test, an industrial method to measure water
uptake by paper, and contact angle measurements. The reactive surfactant was found to
have the best sizing efficiency and focus shifted to synthesizing selected copolymer
surfactants via free radical copolymerization.
Two copolymers were synthesized, with maleic anhydride as the polar part in both. Butyl
methacrylate and lauryl methacrylate were selected as the hydrophobic parts in the
respective copolymer systems. The unavailability of reactivity ratios for the respective
copolymer systems led to the use of in situ proton nuclear magnetic resonance
spectroscopy CH NMR) for the determination of the co-monomer incorporation in both
copolymer systems. Quantitative 13C NMR spectroscopy was also employed in order to
establish the co-monomer content of the isolated copolymers obtained during bench-scale
(laboratory) experiments.
Lastly, a comparison of the degree of surface modification of cellulose was made
between that which was achieved with the industrial reactive surfactant and that with the
two synthesized polymeric reactive surfactants. The two synthesized polymeric
surfactants were found to have a better sizing efficiency than the industrial reactive
surfactant, and the maleic anhydride-lauryl methacrylate copolymer system gave the best
results.<br>AFRIKAANSE OPSOMMING: Die eienskappe en interaksies van sellulose-oppervlaktes is van groot tegniese belang
gedurende die vervaardiging en hergebruik van papier. Oppervlakte behandeling, die
modifikasie van vesel-oppervlaktes bv. met die doel om water indringing in die
papierstruktuur te verminder, speel 'n belangrike rol in die daarstel van papier met goeie
drukkwaliteit en waterweerstand. Waterweerstand is die sleuteleienskap van papier wat in
hierdie werkstuk ondersoek word.
Eerstens is daar 'n vergelyking getref tussen die verandering van sellulose-oppervlaktes
deur middel van anioniese, nie-ioniese en reaktiewe sepe. Die hoeveelheid seep
geabsorbeer deur die papierbord is bepaal en die papier-oppervlak ondersoek deur middel
van skandeer-elektronmikroskopie (SEM). Die behandelingsdoeltreffendheid van die drie
industriele sepe is ondersoek om vas te stel watter seep die beste struktuur het om
hergebruikte papierbord effektief te behandel. Dit is gedoen deur middel van die Cobbtoets,
'n industriele metode om wateropname van papier te meet, asook
kontakhoekmetings. Daar is gevind dat die reaktiewe seep die beste
behandelingsdoeltreffendheid het en daar is vervolgens gekonsentreer op die bereiding
van geselekteerde reaktiewe kopolimeersepe deur middel van vryeradikaalkopolimerisasie.
Twee kopolimere is berei, met maleienanhidried as die polere gedeeite van albei.
Butielmetakrilaat en laurielmetakrilaat is gekies vir die nie-polere gedeeltes van die
onderskeie kopolimeersisteme. Die onbeskikbaarheid van reaktiwiteitsverhoudings vir
die onderskeie kopolimeersisteme het gelei tot die gebruik van in situ proton kern
magnetiese resonansie spektroskopie eH KMR) vir die bepaling van die ko-monomeer
insluiting in beide kopolimeersisteme. Kwantitatiewe koolstofdertienkemmagnetieseresonansie
spektroskopie (13C KMR) is ook gebruik om die ko-monomeerinhoud van die
geisoleerde kopolimere, verkry tydens laboratoriumeksperimente, te bepaal.
Laastens is 'n vergelyking getref tussen die graad van modifikasie van selluloseoppervlaktes
deur middel van die industriele reaktiewe seep in vergelyking met die twee
bereide polimeriese reaktiewe sepe. Daar is gevind dat die twee gesintetiseerde
polimeriese sepe beter behandelingsdoeltreffendheid as die industriele reaktiewe seep het,
met die maleienanhidried-laurielmetakrilaat-kopolimeersisteem wat die beste resultaat
lewer.
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Velyka, A. Ya. "Oxidative modification of proteins under water and salt stress associated with the HgCl2 nephropathy." Thesis, БДМУ, 2020. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/18350.
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Trinh, Pham Thi Doan. "Chemical/thermal modification of poly(vinyl alcohol) film for enhanced water vapour barrier properties." Thesis, Sheffield Hallam University, 2015. http://shura.shu.ac.uk/20225/.
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Within the packaging industry, the increasing demand for sustainable packaging is driving research towards renewable coating materials for paper or paperboard with high barrier properties against gas, water vapour and odours. Poly(vinyl alcohol) (PVOH), a water soluble and biodegradable polymer, is a real option for sustainable packaging when applied as either a coating for paper and paperboard packaging or an independent packaging film. Since its application is limited in high humid environments, several modification methods including chemical crosslinking with glutaraldehyde (GA), salt treatment with sodium sulphate solution, heat treatment and nanoclay incorporation have been investigated in order to improve its barrier to water vapour and also thermal stability and mechanical properties. An extensive range of crosslinking times between GA and PVOH have been assessed. The crosslinked PVOH and salt treated films show an improvement in water vapour barrier properties by 60-70%. Whereas, heat treatment and clay addition show an improvement of 20-57%, in which the water vapour barrier properties increase with increasing heat treatment temperatures (40°C to 180°C) or clay contents (5 to 20 wt%). Additionally, crosslinking PVOH/Clay films with GA improves their water vapour barrier properties comparable to those of crosslinked PVOH films. Apart from the heat treated films, all the modified PVOH films possess higher thermal stability than neat PVOH films as evidenced by thermogravimetric analysis measurements. Combinations between heat treatment and crosslinking with GA as well as crosslinking on one side of PVOH films have been investigated. The films annealed at 180°C prior to crosslinking on both sides do not dissolve in hot water (90°C) even with short crosslinking time (5 minutes) and their water vapour barrier properties derive mainly from their enhanced crystallinity. The respective one-side crosslinked PVOH films show comparable water vapour barrier properties and thermal stability, but were dissolvable in hot water. The diffusion of crosslinking solution into the PVOH films has been studied using in-situ FTIR. It has been shown that the crosslinking solution can rapidly penetrate and diffuse from the top to the bottom of the film (50-60 ?m).The crystallinity of PVOH films after subjection to different modification methods have been investigated using various techniques, including FTIR, Raman and XRD. It has been shown that the crystallinity increases with heat treatment whilst decreases after crosslinking with GA. On the contrary, treating PVOH films with sodium sulphate solution for different lengths of time did not change the crystallinity of the films. When clay is present in PVOH films with 5 wt%, the crystallinity is not affected but increases slightly and significantly with 10 and 20 wt% clay loading, respectively.
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Tsai, Hei-lok, and 蔡希樂. "Parametric study on the fabrication and modification of TiO2 nanotube arrays for photoeletrocatalytic degradation of organic pollutants." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45160259.
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Winkel, Von Kenneth. "Effects of seedbed modification, sowing depth and soil water on emergence of warm-season grasses." Diss., The University of Arizona, 1990. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1990_108_sip1_w.pdf&type=application/pdf.
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Anyango, Joseph Ochieng. "Physico-chemical modification of kafirin microstructures for application as biomaterials." Thesis, University of Pretoria, 2012. http://hdl.handle.net/2263/29708.
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Microparticles produced from kafirin, the sorghum grain prolamin protein, by molecular selfassembly using coacervation with acetic acid solvent are vacuolated. They have shown considerable potential for encapsulation of antioxidants and for preparation of high quality free-standing bioplastic films. However, the functional quality of these kafirin microstructures needs to be improved to exploit their potential application, particularly as biomaterials. Wet heat, transglutaminase and glutaraldehyde treatments were used to modify the physical structure and chemical properties of the kafirin microstructures. Heat treatment (50–96°C) increased microparticle average size by up to four-fold to ≈20 μm, probably due to disulphide cross-linking of kafirin proteins. The vacuoles within these microparticles enlarged up to >10-fold, probably due to greater expansion of air within the microparticles with higher temperature, as the vacuoles are probably footprints of air bubbles. As with heat treatment, glutaraldehyde (10–30%) treatment resulted in oval microparticles, up to about four-fold larger than the control, probably due to covalent glutaraldehyde-polypeptide linkage. Transglutaminase (0.1–0.6%) treatment had only slight effect on the size and shape of microparticles, probably because kafirin has very low lysine content, inhibiting transglutaminase-catalysed cross-linking through ε-(-glutamyl)-lysine bonding. Surface morphology using atomic force microscopy indicated that the microparticles apparently comprised coalesced nanostructures. With heat and transglutaminase treatments, the microparticles seemed to be composed of round nanostructures that coalesced into random irregular shapes, indicative of non-linear protein aggregation. In contrast, with glutaraldehyde treatment, the nanostructures were spindle-shaped and had a unidirectional orientation, probably due to linear alignment of the nanostructures controlled by glutaraldehyde-polypeptide linkage. Thin (<50 μm) films prepared from kafirin microparticles and conventional cast kafirin films were compared in terms of their water stability and other related properties. Films cast from microparticles were more water-stable compared to conventional kafirin films, probably because the large vacuoles within the kafirin microparticles may have enhanced protein solubility in the casting solution, thereby improving the film matrix cohesion. The films prepared from microparticles treated with glutaraldehyde were more water-stable compared to the control, despite the loss of plasticizer, probably due to formation of the covalent glutaraldehyde-polypeptide linkages. The potential of modified kafirin microparticles to bind bone morphogenetic protein-2 (BMP- 2) was investigated. Compared to a collagen standard, the BMP-2 binding capacity of control, heat-treated, transglutaminase-treated and glutaraldehyde-treated kafirin microparticles were 7%, 18%, 34% and 22% higher, respectively, probably mainly due to the vacuoles within the microparticles creating greater binding surface area. The safety, biodegradability and effectiveness of kafirin microparticle film and kafirin microparticle film-BMP-2 system in inducing bone growth were determined by a subcutaneous bioassay using a rat model. Kafirin microparticle film and kafirin microparticle film-BMP-2 system was non-irritant to the animals, probably because kafirin is non-allergenic. The kafirin microparticle film implants showed signs of some degradation but a large proportion of these implants was still intact by Day 28 post implantation, probably because of the low susceptibility of kafirin to mammalian proteolytic enzymes. Kafirin microparticle film-BMP-2 system did not induce bone growth, probably mainly due to low BMP-2 dosage and short study duration. Modification of kafirin microparticles by wet heat or glutaraldehyde treatment both result in increased size of the microparticles with similar gross structure. However, it is apparent that with both treatments the proteins within the pre-formed kafirin microparticles undergo some form of further assisted-assembly through different mechanisms. It seems that heat-induced disulphide cross-linking reinforces a layer around the nanostructures, probably rich in γ- kafirin polypeptides, that stabilizes the structure of the nanostructures. In contrast, glutaraldehyde-treatment appears to destabilize this structure-stabilizing layer through formation of γ-kafirin polypeptide-glutaraldehyde covalent bonding. This probably offsets the balance of attractive and repulsive forces between the different kafirin subclasses within the nanostructures, thereby resulting in collapsed nanostructures and linear realignment. A deeper understanding of the mechanism of kafirin self-assembly will be important for further development of kafirin microstructures for different applications.<br>Thesis (PhD)--University of Pretoria, 2012.<br>Food Science<br>unrestricted
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Ebensperger, Christina [Verfasser]. "Chemical modification of transition metal oxide surfaces by gas phase molecules and liquid water / Christina Ebensperger." München : Verlag Dr. Hut, 2014. http://d-nb.info/1051550246/34.
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孝鎮, 金. "Effects of surface modification and water absorption on the mechanical properties of bamboo fiber reinforced composites." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB10304675/?lang=0, 2009. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB10304675/?lang=0.
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Cates, Stephanie. "Materials modification strategies to improve praseodymium-doped visible-to-ultraviolet upconversion systems for environmental applications." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54907.
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UV radiation is utilized in a number of environmental technologies, most notably for the disinfection of water, air, and surfaces through the use of UVC fluorescent lamps. Recently, our group developed a luminescent material that could emit germicidal UVC simply by irradiating it with a household fluorescent lamp, thus introducing a new type of antimicrobial surface powered by low-intensity visible light. The materials were doped with praseodymium ions (Pr3+) which have the unique capability of converting visible light to higher energy UV using an optical mechanism called upconversion. While visible-to-UV upconversion materials appeared promising for environmental application—particularly because solar irradiation could be used for their activation—their practical application was thwarted by low light conversion efficiencies. Herein we discuss the pursuit of new material forms and modifications designed to improve the efficiency of Pr3+-based upconversion systems. These enabled successful enhancement of antimicrobial activity and led to a proof of concept for upconversion-sensitized TiO2 photocatalysis. Correlations between material properties and optical behavior will be presented, followed by commentary on how these strategies might be used to further advance upconversion systems toward environmental application.
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Colace, Gianmarco. "Modification of Poly(vinyl alcohol) film to maximize barrier properties." Doctoral thesis, Universitat Rovira i Virgili, 2019. http://hdl.handle.net/10803/668477.
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L'alcohol polivinílic (PVA) és el polímer sintètic mes produït al món.
L'excel·lent resistència química i propietats físiques de la resina del PVA han generat un ampli ús a nivell industrial. Els films d'alcohol polivinílic exhibeixen alta resistència a la tensió, resistència a l'abrasió i propietats barrera a l'oxígen, que sota en absencia d`humitat són molt superiors a la majoria d'altres polímers. Els films de PVA són àmpliament utilitzats en aplicacions d'embalatge, on la permeabilitat arriba a ser una propietat crítica a mesurar. Una àmplia sèrie de modificacions poden ser aplicades per canviar la difusió a través dels films. Per a aquest treball van ser triades dos tipus de modificacions: la barreja amb altres polímers hidrosolubles i la preparació d'un material compost.
Segons Robeson, un model en sèrie de matriu i partícules, condueix a un sistema tortuós que, per un gruix donat, disminueix la permeabilitat, mentre els models de Bharadwaj per polímers barrejats van ser utilitzats per a la predicció de la permeabilitat. La producció de film es basa en l'evaporació del solvent: el polímer es dissolt i forma una solució amb una determinada concentració i viscositat; després les partícules o el segon polímer són afegits al sistema; la barreja viscosa és abocada damunt d'un suport de vidre i distribuïda manualment sobre el suport amb un ganivet aplicador regulat amb diferents distàncies. Els experiments de solubilitat van ser realitzats mesurant el temps de dissolució dels films modificats i del polímer de partida i no es van observar diferències després de les modificacions. Els experiments amb el mètode de dry cup van ser duts a terme per mesurar la permeabilitat al vapor d'aigua, registrant una disminució en els valors.<br>El alcohol polivinílico (PVA) es el polímero sintético más producido en el mundo.
La excelente resistencia química y propiedades físicas de la resina de PVA han generado un amplio uso a nivel industrial. Los films de alcohol polivinílico exhiben alta resistencia a la tensión, resistencia a la abrasión y propiedades barrera al oxígeno, que en absencia de humedad son muy superiores a la de la mayoría de polímeros. Los films de PVA son ampliamente utilizados en aplicaciones de embalaje, donde la permeabilidad llega a ser una propiedad crítica a medir. Una amplia serie de modificaciones pueden ser aplicadas para cambiar la difusión a través de los films. Para este trabajo fueron elegidas dos tipos de modificaciones: la mezcla con otros polímeros hidrosolubles y la preparación de un material compuesto.
Según Robeson, un modelo en serie de matriz y partículas conduce a un sistema tortuoso que, para un espesor dado, disminuye la permeabilidad, mientras los modelos de Bharadwaj para mezclas de polímeros fueron utilizados para la predicción de la permeabilidad. La producción de film se basa en la evaporación del solvente: el polímero se disuelve y forma una solución con una determinada concentración y viscosidad; luego las partículas o el segundo polímero son añadidos al sistema; la mezcla viscosa es vertida encima de un soporte de vidrio y distribuida manualmente sobre el soporte con una cuchilla aplicador regulado con diferentes distancias. Los experimentos de solubilidad fueron realizados midiendo el tiempo de disolución de los films modificados y del polímero de partida y no se observaron diferencias después de las modificaciones. Los experimentos con el método de dry cup fueron llevados a cabo para medir la permeabilidad al vapor de agua, registrando una disminución en los valores.<br>Poly(vinyl alcohol) (PVA), a polyhydroxy polymer, is the largest volume, synthetic water-soluble polymer produced in the world.
The excellent chemical resistance and physical properties of PVA resins have resulted in broad industrial use. Poly(vinyl alcohol) films exhibit high tensile strength, abrasion resistance, and oxygen barrier properties which under dry conditions are superior to those of most polymers. PVA films are broadly used in packaging applications, where permeability became a critical property to evaluate. A wide range of modifications can be applied to change the moisture diffusion through the film; two types were chosen for the work: blending with other water-soluble polymers and preparation of a composite.
According to Robeson, a series model of polymeric matrix and particles, leads to a tortuous system, which, for a given thickness, decreases the permeability, meanwhile Bharadwaj models for blended polymer were used for permeability prediction. The film casting is based on solvent evaporation: the polymer is dissolved and forms a solution with a certain concentration and viscosity; then the particles or the second water-soluble polymer are loaded in the system; the viscous mixture is poured on a glass support and spread across it manually with a casting knife set at different gaps. So, the wet film is left to stand to evaporate the solvent and leave a dry film. Solubility experiments were performed, by measuring the dissolution time of the film, and it was not significantly influenced by the material modification. Dry cup method experiments were run to measure the water vapor permeability, recording a decreasing values of permeabilities.
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Fluder, Joseph J. III. "Human Modification of the Upper Middle Rio Grande: Using GIT Techniques to Measure Change Between Albuquerque and Cochiti Dam, New Mexico." Arizona-Nevada Academy of Science, 2003. http://hdl.handle.net/10150/296578.
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Sayre, Hannah Joy. "Modification of Excited State Behavior with Ligand Substitution in Ru(II),Rh(III) Bimetallic Supramolecular Complexes." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/75150.
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The terminal ligand in [(Ph₂phen)₂Ru(dpp)RhCl₂(TL)](PF₆)₃ (Ph2phen = 4,7-diphenyl1,10-phenanthroline; dpp = 2,3-bis(2-pyridyl)pyrazine; TL = terminal ligand – a 4,4′-disubstituted-2,2′-bipyridine where the substituent was carbomethoxy (dcmbpy), hydrogen (bpy) or methyl (Me₂bpy)). The electron-withdrawing ability of the substituent was shown to increase the rate of chloride loss upon electrochemical reduction, facilitating catalytic water reduction. The electronic properties of the terminal ligand also impact the photophysical properties of the molecule. The excited state lifetime of the complex with a dcmbpy terminal ligand was 93 ns while the excited state lifetimes of the complexes with a bpy or Me₂bpy terminal ligand were 44 ns and 47 ns, respectively. Ligand substitution was shown to influence the photocatalytic water reduction activity of these complexes with the dcmbpy complex producing approximately twice the amount of hydrogen (62 ± 7 turnovers in 20 h) as the other two complexes.<br>Master of Science
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Tong, Tianjian. "Co-effects of calcium carbonate and sodium bisulfite modification on improving water resistance of soy protein adhesives." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/14196.
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Master of Science<br>Department of Grain Science & Industry<br>Xiuzhi Susan Sun<br>Bio-based protein adhesives derived from renewable resources, especially soy protein are becoming more significant due to the concerns about environment and health related issues and the limit of petroleum recourses. However, the relatively poor water resistance of soy-based protein adhesives limits its wide applications. The goal of this study was to improve the water resistance performance of soy-based protein adhesives by chemical modification. The specific objectives are 1) to modify soy protein with calcium carbonate (CaCO[subscript]3) and sodium bisulfite (NaHSO[subscript]3) as the denaturing agents; 2) to investigate the effects of calcium carbonate (CaCO[subscript]3) concentrations, curing time and curing temperatures on adhesion performance of the modified soy-based protein adhesives.
In this study, the co-effects of NaHSO[subscript]3 and CaCO[subscript]3 on adhesion properties of soy protein adhesives were investigated. NaHSO[subscript]3 was added to soy flour slurry at constant concentration 6g/L, while concentration of CaCO[subscript]3 was chosen in the range of 0 to 23g/L. Soy protein adhesives modified with 4g/L and 16g/L CaCO[subscript]3 were selected to characterize the adhesion performance on 3 ply yellow pine plywood using the Response Surface Method (RSM). The effects of curing temperature and curing time on the adhesion properties were also studied.
The major findings are 1) 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 modified soy protein adhesives (MSPA) had better adhesion performance (both dry and wet) than 16g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA; 2) Higher temperature (170°C) resulted in higher wet shear adhesion strengths; 3) Longer hot press time had positive impact on wet adhesion shear strength; and 4) 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA showed better adhesion shear strength after 2 weeks storage than 16g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA.
In general, 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA, under longer hot press time and higher temperature would lead to a better adhesion performance.
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Ying, Jia. "Water Droplet Behavior on an Anisotropic Aluminum Fin— A Case Study in Surface Wettability Modification and Control." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1281310217.
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Pouzet, Martial. "Modification de l’énergie de surface du bois par fluoration." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC086/document.
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La disponibilité, les aspects écologiques et économiques du bois sont autant d’avantages qui expliquent le large champ d’applications de ce matériau dans plusieurs domaines tels que la papeterie, l’ameublement, la menuiserie ou la construction. Cependant, le bois est un matériau hygroscopique très sensible aux variations d’humidité et de température ambiante. Le gonflement et le retrait causés par l’adsorption et la désorption de l’eau engendrent des fissures et des déformations dans le bois, le rendant incompatible avec certaines applications.Dans cette étude, une méthode originale a été appliquée sur des échantillons de bois (douglas et sapin) pour diminuer leur caractère hydrophile : la fluoration directe par du fluor moléculaire F2. Le greffage covalent des atomes de fluor sur la surface du bois, grâce à une substitution des groupements C-OH par des liaisons C-F, a été validé par spectroscopie infrarouge et par Résonance Magnétique Nucléaire du 19F.Le bois, qui est intrinsèquement hydrophile, acquiert un caractère hydrophobe comparable à celui du Téflon grâce à la fluoration. Des études de vieillissements sous atmosphère ambiante et irradiation UV ont permis de déterminer une bonne durabilité du traitement. De plus, ce traitement permet d’obtenir un caractère hydrophobe sans changements structuraux (morphologie, densité et couleur) ou mécaniques majeurs. Grâce au caractère surfacique de la fluoration, la conservation de ces propriétés après la fluoration s’avère être un remarquable avantage par rapport aux autres traitements physiques et chimiques classiquement utilisés dans l’industrie du bois<br>The availability, the ecological and economic characteristics of wood are advantages which explain the very wide scope of applications of this material in several domains such as the paper industry, furniture, carpentry and construction. However, wood is a hygroscopic material, highly sensitive to ambient humidity and temperature. The swelling and the shrinking caused by water adsorption and desorption cycles lead to cracking and deformation in the wood volume, making it incompatible for some applications.In this study an original surface treatment was applied to wood samples (douglas and silver fir species) to decrease their hydrophilic character: direct fluorination using F2 gas. The covalent grafting of fluorine atoms onto extreme wood surfaces through a conversion of C-OH groups into C-F was evidenced by Fourier-Transform infrared spectroscopy and 19F solid state Nuclear Magnetic Resonance.The wood which is initially hydrophilic acquires a hydrophobic character comparable to that of Teflon, thanks to fluorination. Good durability of this treatment under ambient atmosphere and UV irradiation was also highlighted. Moreover, because it affects only the extreme surface, this treatment allowed us to obtain a hydrophobic character without major structural (morphology, density and colour) or mechanical changes. The maintaining of these properties after fluorination appears to be a remarkable advantage over other traditional physical and chemical wood treatments
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Vaswani, Sudeep. "Surface modification of paper and cellulose using plasma enhanced chemical vapor deposition employing fluorocarbon precursors." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-01142005-123052/.
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Thesis (Ph. D.)--Chemical Engineering, Georgia Institute of Technology, 2005.<br>Bidstrup Allen, Sue Ann, Committee Member ; Ludovice, Peter, Committee Member ; Hess, Dennis, Committee Chair ; Henderson, Clifford, Committee Member ; Patterson, Timothy, Committee Member.
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Cayuela, Linares Carles. "Ecohydrology of mediterranean headwater catchments the role of forest in the redistribution and isotopic modification of water fluxes." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667405.
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Aquesta tesi té com a objectiu analitzar el paper de la coberta forestal en la redistribució dels fluxos d’aigua, amb la finalitat de millorar el coneixement sobre el funcionament hidrològic de les conques Mediterrànies de capçalera. L’estudi s’ha realitzat a les conques d’investigació de Vallcebre, representatives dels ambients mediterranis de muntanya. Els processos hidrològics s’han estudiat a diferents escales espai-temporals a partir de mesures continues de pluja, trascol, escolament cortical, escorrentia, variables meteorològiques i mostreig dels isòtops estables de l’aigua.
Els resultats obtinguts a escala de parcel·la, en un bosc de Pi roig (Pinus sylvestris L.) i un de roure martinenc (Quercus pubescens Willd.) han demostrat que l’escolament cortical, malgrat representar un percentatge petit de la pluja incident, representa una concentració important d’aigua i partícules directament a la base dels arbres. L’escolament cortical és el resultat d’una combinació complexa de factors biòtics i abiòtics, augmenta a major volum de pluja, però la duració de la pluja, la intensitat o la demanda evaporativa determinen la seva dinàmica temporal. D’altra banda, la mida dels arbres determina la diferent resposta d’individus de la mateixa espècie. En canvi, entre espècies, les diferències estan determinades per la capacitat d’emmagatzemar aigua a l’escorça o les diferents taxes d’evaporació. L’anàlisi de les partícules transportades pel trascol i l’escolament cortical, indica que la interacció entre la matèria particulada i les superfícies vegetals afecta a la mida i a la retenció de partícules. En general, la presència de fulles als roures incrementa la mida de les partícules, i les acícules dels pins augmenten la retenció de partícules. Finalment, cal destacar la pols del Sàhara com una font important de partícules a la zona d’estudi.
Hem observat diferències isotòpiques entre l’aigua de pluja, el trascol i l’escolament cortical. Els processos de fraccionament isotòpic són més evidents per als episodis de baixa magnitud, en els que les capçades no s’arriben a saturar del tot. Aquests processos són deguts a una mescla de factors, per exemple l’evaporació pot ser el factor determinant a l’inici de la pluja, tot i que en condicions d’alta humitat ambiental, l’intercanvi isotòpic (entre aigua i vapor d’aigua) pot adquirir rellevància. En episodis on el senyal isotòpic varia al llarg de la pluja, la retenció de part de la pluja a les fulles i troncs pot produir tan enriquiment com empobriment.
A escala de conca, hem observat que el senyal isotòpic de la pluja, a més de canviar per l’efecte de la coberta, canvia al variar el gradient d’elevació. Amb aquesta informació, hem analitzat l’efecte de la variabilitat espai-temporal del senyal isotòpic d’entrada a la conca de Can Vila sobre els resultats de la separació d’hidrogrames. Els resultats mostren que tot i que els hidrogrames estan dominats per aigua pre-existent a la conca, per algunes crescudes, la contribució d’aigua pre-existent pot variar significativament en funció de la localització del senyal isotòpic d’entrada utilitzat. La comparació dels resultats obtinguts en la separació d’hidrogrames utilitzant diferents senyals isotòpics d’entrada amb els resultats obtinguts utilitzant un senyal mitjà, ha permès definir una estratègia de mostreig “intel·ligent” que millora les separacions d’hidrogrames basades en isòtops estables a escala de petita conca.
En conjunt, els resultats d’aquesta tesi destaquen el rol de l’escolament cortical com a flux preferencial d’aigua i nutrients, que pot afavorir els processos biogeoquímics a la base dels arbres. A més, els resultats recalquen que la variabilitat del senyal isotòpic de la pluja, degut als processos d’intercepció i gradients d’elevació, s’ha de tenir en compte per millorar la comprensió dels processos hidrològics en conques Mediterrànies de capçalera.<br>The present dissertation aims to analyse the role of forest cover on the redistribution of water fluxes and improve the current knowledge on hydrological functioning of Mediterranean headwater catchments. This study has been carried out in the Vallcebre research catchments, an area representative of these Mediterranean mountain environments. Continuous measurements of rainfall, throughfall, stemflow, runoff, meteorological data and stable isotopes of water have been used to investigate hydrological processes at different spatio-temporal scales.
At the plot scale, the findings obtained from a Scots pine (Pinus sylvestris L.) and downy oak (Quercus pubescens Willd.) forest plots have shown that stemflow, despite being only a small portion of the incident precipitation, is a substantial source of water and particulate matter at the base of trees. Stemflow is the result of a complex combination of biotic and abiotic factors, it increases with the event size but the duration of rainfall, intensity or the evaporative demand highly influence its temporal dynamics. In addition, we have found the size of trees to be the main factor producing differences among individuals of each species. However, between species, main stemflow differences have been attributed to different bark storage capacities and different evaporation rates. Besides, through the analysis of the particles contained in throughfall and stemflow, we have observed that the interaction between particulate matter and vegetative surfaces affects the size and the retention of particles. In general, the presence of leaves in oaks increases the size of particles, and needles of pines enhance its retention. We have also found that Saharan dust events are a substantial source of particulate matter in the study area.
Isotopic differences among rainfall, throughfall and stemflow have been observed. Fractionation processes are more evident for events of low rainfall amount, when canopies are not completely saturated. They can be caused by a mixture of factors, for example, evaporation is more likely to have a higher impact at the beginning of rainfall, however, under low evaporation conditions, isotopic exchange (between water and vapour) may acquire more relevance. In addition, for rainfall events with temporal variations of the isotopic composition, the retention of part of the final portion of rainfall on leaves and stems can also produce isotopic differences in both directions, enrichment or depletion.
At the catchment scale we have found that, in addition to the isotopic changes produced by canopy interception processes, the isotopic composition of rainfall also varies along an elevation gradient. Throughout the Can Vila catchment and for several runoff events, the effect of the spatio-temporal variability of the input isotopic signal on hydrograph separation results has been tested. Results have shown that although the Isotopic Hydrograph Separations are dominated by pre-event water, for some floods, the pre-event water contribution can differ significantly depending on the single location of the input isotopic signal used. Comparing hydrograph separation results obtained using different single input signals, with results obtained using a catchment scale input isotopic signal, we could determine the most representative sampling location and define a “smart” sampling strategy for improving Isotopic Hydrograph Separations at the small catchment scale.
Overall, findings gathered in the present dissertation highlight the role of stemflow as a preferential flow path of water and nutrients that can enhance biogeochemical processes at the base of trees during rainfall events. Results also emphasize that the isotopic variability of rainfall, due to canopy interception processes and elevation gradients, has to be taken into account for a better understanding of the hydrological processes in Mediterranean headwater catchments.
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Zibin, Hai. "Modification of Titania with Gold-Copper Bimetallic Nanoparticles and Preparation of Copper-Based Photocatalysts : Application in Water Treatment." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00926757.
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Photocatalysis is recently extensively studied because it implies a variety of potential industrial applications ranging from the hydrogen generation of water splitting to the treatment of waste water. Among all the semiconductors, TiO2 has attracted the most attention. But the rate of the electron-hole recombinations is very important and TiO2 is active only under UV light. Various methods are developed to enhance the photoactivity of TiO2. Other semiconductors like copper oxides and copper sulfides also attracted attention due to their lower band-gaps which allow applications in solar photocatalysis. In this work, different kinds of photocatalysts were developed and studied: surface modified TiO2 with metal nanoparticles and copper sulfides and oxides. The nanostructures were characterized by different techniques: HRTEM, SEM, XRD, XPS, HAADF-SEM, and TRMC. Their photocatalytic activity was studied for degradation of model pollutants: phenol, rhodamine B and methyl orange. Different chemical and radiolytic methods have been investigated to modify the surface of TiO2 by mono- and bimetallic (Au, Cu and Au-Cu) nanoparticles in the aim to improve its photocatalytic activity. The best results in term of photocatalytic activity have been obtained with reduction of THPC (tetrakis (hydroxymethyl) phosphonium chloride) and with radiolytic reduction after deposition with urea. Titania surface modification with Au, Cu and bimetallic Au-Cu NPs enables the increase of the photocatalytic activity under UV light. We have found that very small amounts of metal (0.5% wt.) can activate titania for photocatalytic applications, thus the costs of photocatalyst preparation are relatively low. Radiolytic syntheses of non-TiO2 photocatalysts including Cu2O and CuS nanostructures with different morphologies have been developed. The photocatalytic activity of the synthesized photocatalysts has been studied. Truncated octahedral Cu2O exhibit an excellent photocatalytic activity under visible illumination. CuS nanotubes (NTs) exhibit both a high ability to adsorb dyes and a photocatalytic activity under visible light.
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Atallah, Charbel. "Surface Modification and In-process Steam Cleaning of Ceramic Membranes Used In the Treatment of Wastewaters Containing Bituminous Fines." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39786.
Full textAbstract:
Synthetic membranes have a high separation efficiency, small footprint, low energy consumption and ease of operation, making them an attractive alternative to traditional separation operations. For this reason, membranes have been extensively studied for the treatment and recycling of bitumen-containing wastewaters. Such wastewaters include petroleum produced water, residual pipeline cleaning solutions and contaminated water from oil spills. Ceramic membranes are preferred in these applications over polymeric membranes because they are highly resistant to solvents and can be operated at high temperatures over a wide range of pH. Fine clays and silicates, coated with bitumen, are significant foulants for membrane filtration systems. These foulants possess acidic, basic and amphoteric groups, leading to the presence of both positive and negative surface charges. Ceramic membranes in aqueous media have a pH dependent surface charge. It was hypothesized that these surface charges are responsible for the high fouling of ceramic membranes that is observed when treating wastewaters containing bituminous fines.
The overall objective of this research was to reduce fouling and increase the lifetime of ceramic membranes in treating oil sands produced water; an example of a wastewater containing bituminous fines. This goal was achieved through the surface modification of the ceramic membrane’s selective layer, as well as by the implementation of a novel in-place steam regeneration technique. All membrane filtration tests were performed with field samples of oil sands produced water that were supplied to CanmetMINING (NRCan) by three Canadian oil sands companies.
Organosilanes are silicon-based monomers that can possess a wide array of chemical functionality due to their organic moieties. They are capable of reacting with oxide surfaces, and have seen extensive use as surface modification agents for ceramic membranes in various applications. To maintain desirable hydrophilic properties without surface charges, highly hydrophilic and non-ionic polyethylene oxide (PEO) based organosilanes were identified. These PEO-silanes were then used to modify ceramic membranes of several different selective layer materials, and the thermal stability of the silane layer was studied using FTIR, SEM, zeta potential and contact angle measurements. The modification procedure with PEO-silanes was first applied to lab-scale membrane disks, and subsequently to commercial scale multilumen membrane tubes that were tested in a pilot-scale system at CanmetMINING. Results obtained from both sets of experiments were promising and demonstrate that ceramic membranes can be surface modified in a way that successfully renders them fouling resistant to the bituminous fines present in these wastewaters. Upon surface modification, foulants were more readily released from the membrane surface, resulting in an enhanced flux and separation performance.
A novel steam regeneration technique was also applied as a means of bituminous fouling alleviation. This technique was tested in the CanmetMINING pilot-scale system and consisted of periodically injecting steam into the membrane lumen feed channels during operation. Direct steam injection rapidly heated foulant cake layers, and water droplets in the saturated steam caused surface abrasions that ultimately resulted in the scouring of bitumen away from the membrane surface. Membrane fluxes when steam regeneration was active were up to 4 times higher when compared to tests where only traditional permeate backflushing was used.
The fouling remediation techniques developed in this work have broad potential applicability in ceramic membrane filtration systems aimed at treating all wastewaters containing bituminous compounds, such as process waters in general and contaminated water from oil spills.
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Chingombe, Purazen. "Removal of organic micropollutants and trace metal from water using modified activated carbons." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/7793.
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Pollution of water by herbicides and heavy metals has caused world wide concern because of the adverse effects of these pollutants on the environment, humans and wildlife. This has resulted in tighter legislation being imposed on the levels of these pollutants in drinking water. For example, the European Union (EU) has set the legislation in the drinking water Directive Admissible Concentration for a single herbicide to a maximum of 0.1 ppb. Despite the tight environmental pollution controls, isolated cases of pollutants exceeding their limits are still encountered. This would suggest that research towards the efficient and effective removal of these pollutants will be an on-going process. In this study, sorption of copper and some selected herbicides e.g. atrazine, benazolin and 2,4-dichlorophenoxyacetic acid (2,4-D) was undertaken on a conventional activated carbon and its modified series. A low level detection method was developed using High Performance Liquid Chromatography (HPLC) and this system was used to quantify the sorption capacity of the herbicides. In order to understand the sorption mechanism of the targeted pollutants, physical and chemical characterisation of the adsorbents was undertaken using a variety of techniques. These include, Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared (FT-IR) method, pore size distribution and surface area measurements, elemental analysis, sodium capacity determination, zeta potential and pH titration. The sorption data were presented and analysed by conventional adsorption isotherms. Sorption of the herbicides was favoured on carbon samples with least oxygen content while the uptake of copper was strongest in oxidised carbons. Kinetic experimental data were analysed by a pseudo second order model and the Boyd kinetic model. Molecular structural configurations and the physico-chemical properties of the adsorbent played a crucial role in the sorption behaviour of the herbicides.
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Zhu, Xiangwei. "Unfolding, crosslinking and co-polymerization of Camelina protein and its use as wood adhesives." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/35420.
Full textAbstract:
Doctor of Philosophy<br>Department of Grain Science and Industry<br>X. Susan Sun<br>Oilseed protein is a promising renewable source to be used as the replacement of petroleum-based materials for adhesion purpose, and it has drawn increasing attention since soy-based adhesives were developed for wood glues. However, soy protein comprises a portion of humans’ diets, thereby creating competition between utilization of soy protein for protein-based products or human food. Therefore, alternative bio-resources must be discovered. Proteins from camelina sativa provide such potential. Similar to other protein-based polymers, low mechanical strength and poor water resistance are the major drawbacks limiting camelina protein’s further applications. In this research, camelina protein (CP) was modified by unfolding, crosslinking, and co-polymerization treatment for improved flow-ability, adhesion properties and water resistance, which facilitates the industrialization of camelina as an alternative to soy-based adhesives. The physicochemical properties and microstructures of CP were also investigated.
To increase the reactivity of CP adhesive, the first step is to denature the folded structure of native proteins. Camelina protein was extracted from defatted camelina meal through alkali solubilization and acid precipitation and modified with varying amount of NaHSO₃ (0-12% of the protein dry base) and Gdm.Cl (0-250% of the protein dry base). NaHSO₃ treatment broke the disulfide bonds of the CP and thus increased its free sulfhydryl content and surface hydrophobicity. As NaHSO₃ concentration increased, the viscosity, elastic modulus (G') and water resistant of NaHSO₃-modified camelina protein (SMCP) dispersion decreased, and the protein became hydrophobic. Gdm.Cl treatment broke the CPI’s hydrogen bonds but decreased their surface hydrophobicity. Similarly, viscosity, G', and water resistant of Gdm.Cl-modified camelina protein (GMCP) dispersions decreased as Gdm.Cl increased and protein became to aggregate. The reducing effect of NaHSO₃ was more obvious than Gdm.Cl to disrupt CPI’s intermolecular protein interaction but less obvious than Gdm.Cl to reduce the viscosity and water resistant.
To further increase the CP’s water resistance, a coupling agent, Ethyl-3-(3-dimethyl-aminopropyl-1-carbodiimide) (EDC), was applied to stabilize the protein structure by crosslinking the free carboxyl groups and amino groups. The cross-linked CP exhibited increased molecular weight and particle size. Microstructures of modified CP also became rigid and condensed. Accordingly, CP’s increased intermolecular protein interaction resulted in its higher elastic modulus, viscosity and water resistance. The ultrasound pretreatment further increased the crosslink degree of CP, which resulted in protein’s increased aggregation behaviors and compact micro-structures. Consequently, the elastic modulus, viscosity, and water resistance of CP increased accordingly.
Copolymerization with hydrophobic enhancers was also an effective method to improve CP’s water resistance. In this study, kraft lignin was oxidized by H₂O₂ and then copolymerized with CP as wood adhesives, which exhibited increased wet strength. In the presence of ultrasound irradiation, the H₂O₂-depolymerized kraft lignin exhibited reduced particle size, thermal stability and increased content of hydroxyl groups. Fluorescence spectroscopy analysis revealed that after coupling with pristine or de-polymerized lignin, CP exhibited increased hydrophobicity due to lignin’s increased reactivity with camelina protein. Accordingly, the water resistance of CP-based adhesives improved. In the optimized condition, when CP was copolymerized with ultrasound-induced oxidized lignin, it had increased wet shear adhesion strength from 0.28 MPa to 1.43 MPa, with wood panels passing the three-cycle water soaking test.
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De, Stefano Vittorio. "Origins of specificity in protein modification, reaction patterns of tris-trimesates with human hemoglobin A, water, and n-propylamine." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0015/NQ45655.pdf.
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Tang, Zhong. "Synthesis and Modification of MFI-Type Zeolite Membranes for High Temperature Hydrogen Separation and Water Gas Shift Membrane Reactions." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1283192205.
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Sethi, J. (Jatin). "Cellulose nanopapers with improved preparation time, mechanical properties, and water resistance." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526221540.
Full textAbstract:
Abstracts Cellulose nanopapers are the strongest polymeric material known to us, and in the near future, they are likely to be a backbone of numerous functional materials. Cellulose nanopapers have gained much attention due to qualities such as their environmentally friendly nature, renewable raw material source and biodegradability. Additionally, they offer an industrially adaptable, water-based processing route, which is similar to current paper production. Functionally, besides being tougher than any known plastic, cellulose nanopapers remain foldable like a paper. Despite their fascinating properties, cellulose nanopapers are still far from commercialisation – mainly due to two obstacles. Firstly, it can take up to hours to prepare a nanopaper due to poor draining of cellulosic nanofibres. Secondly, cellulose nanopapers have extremely poor water and humidity resistance, as up to 90% of their stiffness is lost in the presence of water. The purpose of this dissertation is to address both obstacles and suggest an eco-friendly yet industrially relevant solution. Two approaches are employed: increasing the hydrophobicity of cellulose nanofibres with lactic acid and ultrasonication (Paper I and II), and combining cellulose nanofibres with hydrophobic materials, such as polyurethane (Paper III) and lignin-rich entities (Paper IV). By using these methods, the preparation time was improved by 75% (Paper II) and by 70% (Paper IV) respectively. All reported nanopapers were significantly more tolerant of water and moisture than the reference nanopaper. The mechanical properties were also improved in Paper I and IV. Additionally, all reported nanopapers were thermally stable. This thesis also discusses the importance of quick draining in cellulose nanofibre-reinforced paper products. The results of this study are likely to aid the commercialisation of cellulose nanopapers in practical applications and the use of cellulose nanofibres in other materials, such as reinforcing paperboards. All methods used in this thesis are water-based<br>Tiivistelmä Selluloosapohjaiset nanopaperit ovat lujimpia tunnettuja polymeerimateriaaleja ja lähitulevaisuudessa niiden voidaan odottaa luovan perustan useille funktionaalisille materiaaleille. Nanopaperit ovat saaneet paljon huomiota ympäristöystävällisyytensä, uusiutuvan raaka-aineensa ja biohajoavuutensa ansiosta. Lisäksi niiden valmistusprosessi on vesipohjainen ja samankaltainen kuin tavallisen paperin valmistukseen käytetty teollinen prosessi. Käyttöominaisuuksiltaan ne ovat erinomaisia, sillä vaikka niiden sitkeys on parempi kuin tunnetuilla muoveilla, ovat ne silti paperin tavoin taiteltavia. Kiehtovista ominaisuuksistaan huolimatta selluloosapohjaiset nanopaperit ovat kuitenkin vielä kaukana kaupallistamisesta ja tähän vaikuttavat pääosin kaksi tekijää. Tärkein syy on selluloosananokuitujen kuivattamisen ja näin ollen nanopaperin muodostamisen vaatima huomattavan pitkä aika. Nykyisillä menetelmillä nanopaperin valmistaminen kestää useita tunteja. Toinen syy on niiden erittäin huono veden- ja kosteudenkestävyys. Ne menettävät jopa 90 % jäykkyydestään veden vaikutuksesta, mikä rajoittaa niiden käyttöä kosteissa ja vesiroiskeille alttiissa kohteissa. Tämän väitöskirjatutkimuksen päätavoitteena on löytää ekologisesti kestävä ja teollisuudessa hyödynnettävissä oleva menetelmä molempien edellä mainittujen ongelmien ratkaisemiseksi. Työssä noudatetaan kahta eri lähestymistapaa: lisätään selluloosananokuitujen hydrofobisuutta maitohapon ja ultrasonikoinnin avulla (Artikkelit I ja II), ja yhdistetään selluloosananokuituihin hydrofobisia materiaaleja, kuten polyuretaania (PU) (Artikkeli III) ja ligniinipitoisia yhdisteitä (Artikkeli IV). Näitä menetelmiä käyttämällä valmistusaikaa saatiin lyhennettyä 75 % (Artikkeli II) ja 70 % (Artikkeli IV). Kaikki valmistetut nanopaperit olivat huomattavasti veden- ja kosteudenkestävämpiä kuin verrokkinäytteet sekä osoittivat lämpöstabiiliutta. Lisäksi mekaanisia ominaisuuksia saatiin parannettua Artikkeleissa I ja IV. Tässä työssä käsitellään myös nopean kuivattamisen tärkeyttä selluloosananokuitulujitteisten paperituotteiden valmistuksessa. Saadut tulokset todennäköisesti edistävät selluloosapohjaisten nanopaperien kaupallistamista ja selluloosananokuitujen hyödyntämistä esimerkiksi kartongin lujitemateriaalina. Kaikki työssä käytetyt menetelmät ovat vesipohjaisia
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Gui, Minghui. "IRON AND IRON OXIDE FUNCTIONALIZED MEMBRANES WITH APPLICATIONS TO SELECTED CHLORO-ORGANIC AND METAL REMOVAL FROM WATER." UKnowledge, 2014. http://uknowledge.uky.edu/cme_etds/37.
Full textAbstract:
The development of functionalized membranes with tunable pores and catalytic properties provides us an opportunity to manipulate the membrane pore structure, selectivity and reactivity. By introducing the functional groups into membrane pores, dissolved metal ions and reactive particles can be effectively immobilized within the polymer matrix for toxic chloro-organic and heavy metal remediation in water.
A polyelectrolyte functionalized membrane platform with tunable pore size and ion exchange capacity has been developed for iron/iron oxide nano-catalyst synthesis and chlorinated organic compound (trichloroethylene, TCE and polychlorinated biphenyls, PCBs) degradation. Highly robust polyvinylidene fluoride (PVDF) microfiltration membranes are used as the support with cross-linked polyacrylic acid (PAA) filled in the pores. By varying the environmental pH, PAA hydrogels have either swelling or collapsing behavior, resulting in different effective membrane pore sizes for different separation purposes. Cation exchange groups (i.e. carboxyl groups) in PAA chains prevent the aggregation and leaching of nanoparticles (NPs) during in-situ synthesis and reaction. Depending on the catalyst loading and residence time, TCE and PCBs can be completely degraded by reduction of zero-valent iron and bimetallic iron/palladium NPs, or iron oxide catalyzed free radical oxidation at near-neutral pH. Biphenyl from PCB dechlorination can be further oxidized by hydroxyl radicals (OH•) generated from hydrogen peroxide (H2O2) decomposition. Hydroxybiphenyls and benzoic acid are identified as oxidation products. Line scan and elemental mapping in transmission electron microscopy (TEM) and X-ray photo electron spectroscopy (XPS) characterizations are conducted to understand the effect of iron surface transformation on NP reactivity, and to optimize the membrane functionalization.
The same platform can also be used to remove toxic metal selenium in the scrubber water of coal-fired power plants. By reducing the salt concentration in water or increasing the residence time and temperature, the concentration of selenium oxyanions in functionalized membrane permeate can be reduced to less than 10 µg/L. Selenium is captured in membranes by both iron reduction to metallic selenium and iron oxide adsorption. The full-scale flat sheet functionalized membrane and spiral wound modules have also been developed. Iron NPs with alterable loadings are successfully synthesized inside the membrane module for real water applications.
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Zhu, Xing. "Development of alkali hexatitanate photocatalysts and co-catalysts for photocatalytic reduction of carbon dioxide by water." Doctoral thesis, Kyoto University, 2020. http://hdl.handle.net/2433/253386.
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京都大学<br>0048<br>新制・課程博士<br>博士(人間・環境学)<br>甲第22550号<br>人博第953号<br>新制||人||226(附属図書館)<br>2019||人博||953(吉田南総合図書館)<br>京都大学大学院人間・環境学研究科相関環境学専攻<br>(主査)教授 吉田 寿雄, 教授 内本 喜晴, 教授 田部 勢津久<br>学位規則第4条第1項該当<br>Doctor of Human and Environmental Studies<br>Kyoto University<br>DFAM
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Krumpen, Thomas [Verfasser]. "Investigation of ice formation and water mass modification in eastern Laptev Sea polynyas by means of satellites and models / Thomas Krumpen." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2010. http://d-nb.info/1035033038/34.
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Forrest, Eric Christopher. "Nanoscale modification of key surface parameters to augment pool boiling heat transfer and critical heat flux in water and dielectric fluids." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/52799.
Full textAbstract:
Thesis (S.M. and S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2009.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (p. 123-130).<br>Surface effects on pool boiling heat transfer and the critical heat flux are well documented but poorly understood. This study investigates the pool boiling characteristics of various fluids, and demonstrates that surface effects can drastically alter the nucleate boiling heat transfer coefficient as well as the critical heat flux. Changes in surface morphology and surface chemistry are suspected to be the primary factors influencing pool boiling heat transfer. The relative impact of surface properties is shown to depend strongly upon the working fluid. To evaluate the effects of chemical constituency and surface texture on the pool boiling of water, nanoparticle thin-film coatings are applied to nickel and stainless steel substrates using the layer-by-layer assembly method. This study shows that such coatings, with thicknesses on the order of one micron or less, are capable of enhancing the critical heat flux of water up to 100%, and enhancing the nucleate boiling heat transfer coefficient over 100%. Through the use of thin-film coatings, the importance of nanoscale surface texture, porosity, and chemical constituency on boiling mechanisms is revealed. Low surface tension dielectric fluids, including a recently developed fluorinated ketone with a low global warming potential, are tested to determine their pool boiling heat transfer capabilities. The potential for nanoparticle-based pool boiling enhancement in well-wetting dielectric fluids is investigated. The role of surface wettability and adhesion tension on the incipience of boiling, nucleate boiling, and critical heat flux are considered.<br>(cont.) Results indicate that the low global warming potential fluorinated ketone may be a viable alternative in the cooling of electronic devices. Additionally, results demonstrate that enhancement of boiling heat transfer is possible for well-wetting dielectric fluids, with 40% enhancement in the critical heat flux using dilute suspensions of aluminum or silica nanoparticles in the fluorinated ketone.<br>by Eric Christopher Forrest.<br>S.M.and S.B.
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Van, Noordwyk Marelize. "Interaction of water deficit, canopy modification and ripening : effect on the phenolic and colour composition of Shiraz grapes & subsequent wine." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71763.
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Thesis (MScAgric)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: Phenolic compounds are important quality indicators of a red wine, as they can contribute to the
colour of a young red wine, colour stability during ageing as well as astringency, bitterness,
body and overall mouthfeel properties. Wine composition is commonly influenced by
winemaking and viticultural practices.
In South Africa it often happens that vines are excessively vigorous, resulting in canopies
that are too dense, which in turn could have a negative effect on the quantity and quality of the
grapes produced. Viticultural practices such as judicious canopy management and irrigation are
designed to control vine vigour and yield, thus improving fruit ripening and colour development.
Artificial shading and water deficit have been reported to have an influence on the sensory
properties of red wine as well as on the flavonoid composition. These effects are dependent on
a number of factors, however, including the season, cultivar, light intensity, and the extent and
timing of water deficit.
There is limited research on the possible interactive effects of grapevine water deficits and
canopy manipulation on grape and wine flavonoid composition in Shiraz, as well as the
relationships between berry and wine composition. We thus investigated the effect of canopy
reduction in combination with water deficit on the phenolic and colour composition of Shiraz
grapes at different levels of ripeness, and in their corresponding wines after alcoholic and
malolactic fermentation as well as after six months’ ageing. This study found that it is possible to
improve the phenolic composition of grapes and wine by shoot removal, and some of the
tendencies in the wines were also observed after the ageing period. If the shoot removal is not
performed at a very early stage, sunburn damage can occur and this will result in berries with a
lower mass and volume at harvest due to excessive exposure without the berry having adapted
to the imposed conditions.
Harvesting at different ripeness levels also affected the chemical and phenolic composition
of the grapes and resulting wines. The water deficit effect on most phenolic parameters
measured in the grapes and wine was not as prominent as that of the canopy manipulation
treatment.
This study improved our understanding of how an improvement in the canopy microclimate
of Shiraz could be reflected in the phenolic composition of wines, along with a potentially
important effect of harvesting date. On this basis it may be possible to attain a specific wine
style. Harvesting at a ripe stage, for example, could result in the production of wines with higher
colour density and astringency, while unripe grapes could result in wines with higher levels of
perceivable fresh berry attributes. In particular, canopy reduction could increase the astringency
and body of wines made from grapes subjected to water deficit.<br>AFRIKAANSE OPSOMMING: Fenoliese verbindings is belangrike kwaliteitsparameters van rooiwyn, aangesien dit kan bydra
tot die kleur van ‘n rooiwyn, kleurstabiliteit tydens veroudering sowel as frankheid, bitterigheid
en mondgevoel. ‘n Wyn se fenoliese samestelling word algemeen bepaal deur wynmaak- en
wingerdkundige praktyke.
In Suid-Afrika gebeur dit gereeld dat wingerde uitermatig groeikragtig is, wat lei tot te digte
lower wat sodoende ‘n negatiewe effek op kwantiteit en kwaliteit van die druiwe wat
geproduseer word, het. Wingerdkundige praktyke soos oordeelkundige lowerbestuur en
besproeiing is ontwerp om wingerdstokke se groeikrag en opbrengs te beheer, en sodoende
vrugrypwording en kleurontwikkeling te verbeter.
Kunsmatige beskaduwing en waterstres is gerapporteer om ‘n invloed te hê op die
sensoriese eienskappe van rooiwyn sowel as op die flavonoïedsamestelling. Hierdie effekte is
egter afhanklik van ‘n verskeidenheid faktore, insluitende die seisoen, kultivar, ligintensiteit en
die mate en tyd van waterstres toegepas.
Daar is beperkte navorsing op die moontlike interaktiewe effekte van waterstres en
lowermanipulasie op die druif en wyn flavonoïedsamestelling in Shiraz, sowel as die
verhoudings tussen druif en wyn samestelling. Ons het dus die effekte van lowerbestuur in
kombinasie met waterstres op die fenoliese en kleursamestelling van Shiraz druiwe by
verskillende rypheidsvlakke ondersoek, asook in hul ooreenstemmende wyne na alkoholieseen
appelmelksuurfermentasie sowel as na ses maande veroudering. Hierdie studie het gevind
dat dit moontlik is om die fenoliese samestelling van druiwe en wyn deur lootverwydering te
verbeter, en sommige van die tendense is ook waargeneem in die wyn na die
verouderingsperiode. Indien lootverwydering nie toegepas word by ‘n baie vroeë stadium nie,
kan sonbrand voorkom en dit kan lei tot korrels met ‘n laer massa en volume by oes as gevolg
van oormatige blootstelling sonder dat die korrel aangepas het by die spesifieke kondisies.
Oes by verskillende rypheidsvlakke affekteer ook die chemiese en fenoliese samestelling
van die druiwe en ooreenstemmende wyne. Die waterstreseffek op meeste van die fenoliese
parameters gemeet in druiwe en wyn was nie so prominent soos dié van die lowermanipulasie
behandeling nie.
Hierdie studie het ons begrip verbeter van hoe ‘n verbetering van die lower mikroklimaat
van Shiraz gereflekteer kan word op die fenoliese samestelling van die wyn, saam met ‘n
potensiële belangrike effek van oesdatum. Op grond van hierdie basis is dit dus moontlik om ‘n
spesifieke wynstyl te verkry. Oes by ‘n ryp stadium, byvoorbeeld, kan die produksie van wyn
met ‘n hoër kleurdigtheid en frankheid tot gevolg hê, terwyl onryp druiwe wyne met hoër vlakke
van waarneembare vars bessiekenmerke tot gevolg kan hê. Verlaging van lowerdigtheid kan
veral die frankheid en mondgevoel van wyne gemaak van druiwe blootgestel aan waterstres,
verbeter.
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Bahareh, Bahramian. "Purification and Modification of a Biodegradable, Carbone Dioxide Based Polymer: A Sustainable Solution to Reduce Consumption of Non-degradable Plastics." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15483.
Full textAbstract:
The aim of this study was to develop a benign process for removal of metal residue and other impurities from biodegradable poly(propylene carbonate) (PPC) to broaden its applications. It was demonstrated that the properties of PPC are favourable for fabrication of medical devices and food packaging products. For Instance, mechanical properties of PPC were either comparable or superior to commercial polymers such as low density polyethylene and polybutyrate adipate terephthalate (Eco-Flex). Besides, permeability of PPC to oxygen and moisture was remarkably lower than these polymers. Furthermore, PPC was chemically stable in food simulated media. The high level of zinc glutarate, a metal-based catalyst, in PPC was remarkably reduced by using a novel technique in which CO2 laden water was used as a solvent. The extraction efficiency of this method at 45 ˚C and 70 bar was nearly 90% that was two-fold higher than using acidic solvents. Additionally, at these conditions other impurities such as cyclic propylene carbonate were removed from PPC that further promoted its properties. For example, the thermal decomposition temperature of PPC was shifted from 124˚C to 214˚C and its mechanical strength was enhanced by 40%. Plasma modification was used as an efficient method for chemical immobilization of thymol, an active, natural antimicrobial agent on PPC surface. The results of bacterial counting and bacteria inhibition zone showed that the thymol immobilization was efficient when using plasma at low energy for a period of 15 minutes. This study led to design of two benign processes for purification of PPC and fabrication of its antimicrobial films. This antimicrobial, biodegradable polymer that eradicates the use of preservatives and metal nano-particles is attractive for biomedical devices and food packaging products. Commercialization of theses methods will be of great value for reducing the disposal of non-degradable polymer in landfills that is a huge environmental issue.
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King, Stanley Wayne. "Mass Transfer Analysis of Polyether Sulfone and Polyamide Membranes Modified by Ion Beam Irradiation." University of Toledo / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1083875419.
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Fernandes, João Carlos Martins. "Mineral stress response of Vitis cell wall transcriptome: identification, characterization and expression of genes from key families involved in wall biosynthesis and modification." Doctoral thesis, ISA-UL, 2015. http://hdl.handle.net/10400.5/12054.
Full textAbstract:
Doutoramento em Engenharia Agronómica - Instituto Superior de Agronomia - UL<br>Grapevine (Vitis vinifera L.) is one of the most economically important fruit crops in the world. Abiotic stresses are likely to affect the plant development, yield and ultimately the quality of economic products. The cell wall (CW) is a dynamic structure that determines plant form, growth and response to environmental conditions. To investigate V. vinifera CW adaptative response to restrictions in major nutrients, essential to plant growth and development, N, P and S were excluded from V. vinifera callus and shoots growing substrates. Water stress on berry skin CW was studied in non-irrigated versus irrigated plants of two varieties. Specific CW components, namelly cellulose, were impacted in callus, shoots and berries subjected to abiotic stress. To overcome this, V. vinifera CWs suffered compositional changes and reorganization of deposition of several CW components, in particular the degree and pattern of pectin methyl-esterification, arabinan and XyG, which together promote stiffening of the CW. Moreover, polysaccharides of callus grown under mineral deficiency, mainly N, were more tightly bound in the CW. Under mineral stress the expression of genes from CW candidate enzyme families was affected for example downregulation of GH9C, XTHs with predicted hydrolytic activity and PMEs were observed. In shoots probed with CW-epitope monoclonal antibodies an increase in pectins with a low degree of methyl-esterification able to dimerise association through calcium ions was observed. CWs grown under N deficiency were enriched in 1,5-arabinan rhamnogalacturonan-I (RG-I) side chains. The impact on CW was dependent on the mineral stress, nitrogen leading to more pronounced responses, supporting the primary role of this major nutrient in plant development and metabolism. Water shortage affected berry skin by stiffening the CW, probably due to alterations in PGs, XTH and PME expression and pectin methyl-esterification in a variety dependent way