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Artykuły w czasopismach na temat "Chemical routes"
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RAO, C. N. R. "CHEMICAL ROUTES TO NANOCRYSTALS, NANOWIRES AND NANOTUBES". International Journal of Nanoscience 04, nr 05n06 (październik 2005): 811–26. http://dx.doi.org/10.1142/s0219581x05003747.
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Soft chemical routes are employed effectively for the synthesis of nanocrystals of semiconductor materials. Several methods have been developed for the synthesis of multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) and specially noteworthy are the precursor route and nebulized spray pyrolysis for the synthesis of MWNTs and junction nanotubes. Nanotubes of inorganic layered materials are obtained by ingenious chemical methods. Nanowires of inorganic materials can be synthesized not only by high-temperature methods such as the carbon-assisted route but also by soft chemical routes.
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Pepelko, William E., i James R. Withey. "Methods for Route-To-Route Extrapolation of Dose". Toxicology and Industrial Health 1, nr 4 (październik 1985): 153–75. http://dx.doi.org/10.1177/074823378500100410.
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Results of acute toxicity studies for a variety of chemicals have indicated that, in most cases, although the inhalation route was more effective than the IG route, wide variations in toxicity occurred between these two routes. The major factors that may result in variations in toxicity between routes include: (1) differences in absorption efficiency; (2) differences in systemic effects; (3) occurrence of critical toxicological effects at the portal of entry; (4) first-pass effects resulting in inactivation or activation of the chemical agent before it reaches the target organ; and (5) variations in temporal patterns of target organ concentrations. Extrapolation to determine safe exposure levels during chronic exposure becomes less reliable, not only as information relating to these factors decreases, but also as the quality or length of exposure decreases in the available toxicologic studies. VDC is an example of one of a few chemicals for which both chronic inhalation and oral toxicity data are available, along with detailed pharmacokinetic information. On the basis of the pharmacokinetic data, differences in toxicity between the two routes did not appear to be very likely for this chemical. This conjecture was supported by the results of chronic toxicity studies. Finally, assuming sufficient data and pharmacokinetic parameters are available, this paper presents a useful and practical approach to route extrapolation.
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Ovchinnikova, Elena L., Andrey S. Kolchin, Aleksander S. Kriga i Yuliya A. Novikova. "Carcinogenic risk to the health of the population of a large industrial city as a result of multi-environmental and multi-route exposure to chemicals". Hygiene and sanitation 103, nr 8 (10.09.2024): 906–13. http://dx.doi.org/10.47470/0016-9900-2024-103-8-906-913.
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Introduction. Despite the relatively low average annual mortality rate, the increased incidence of cancer in the population of the Omsk region, together with indicators of the quality of oncological care, indicate a tense epidemiological situation. The purpose of the study is to determine priority environments and routes of exposure to chemicals in the formation of long-term carcinogenic risks in the city of Omsk. Materials and methods. There were used results of environmental and social-hygienic monitoring of habitat objects for the period 2017–2022. To assess the cumulative carcinogenic risk, atmospheric air, drinking tap water, open water, soil, food products, and 3 routes of exposure were taken into account: inhalation, oral and cutaneous. The assessment of carcinogenic risks was carried out in accordance with Guideline R 2.1.10.3968–23, taking into account the severity coefficient of malignant neoplasms. Results. The carcinogenic risk to the health of the population of the city of Omsk as a result of multi–environmenal and multi-route exposure to chemicals was assessed as alarming (high in an the engraved script). The structure of contributions to the cumulative carcinogenic risk: drinking water – 63.3%, atmospheric air – 33.1%, food products – 3.3 %, other environments less than 0.5%. The main route of entry of chemical carcinogens is inhalation (77.4%). Alarming carcinogenic risks were formed through the inhalation route of chloroform from drinking water; chromium VI, formaldehyde, benzene, and soot from atmospheric air. Among the target organs of malignant neoplasms, the greatest risk was in the gastrointestinal tract, which was assessed as alarming. Limitations. Not all habitat objects were analyzed, which may reduce the objectivity of the conclusions. Conclusion. An assessment of the long-term cumulative carcinogenic risk made it possible to prioritize the list of chemical pollutants, environmental objects, and routes of exposure to carcinogens. For more accurate planning of sanitary and hygienic measures to reduce public health risks, improve comprehensive monitoring of pollutants in all environments, taking into account all routes of entry into the human body, it is advisable to analyze the total risks for multi-environmental and multi-route exposure with an analysis of the contribution of chemicals, media, routes to their formation.
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Cossutta, Matteo, Jon McKechnie i Stephen J. Pickering. "A comparative LCA of different graphene production routes". Green Chemistry 19, nr 24 (2017): 5874–84. http://dx.doi.org/10.1039/c7gc02444d.
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Corma, Avelino, Sara Iborra i Alexandra Velty. "Chemical Routes for the Transformation of Biomass into Chemicals". Chemical Reviews 107, nr 6 (czerwiec 2007): 2411–502. http://dx.doi.org/10.1021/cr050989d.
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Schmidt, H. "Chemical routes to nanostructured materials". Materials Science and Technology 16, nr 11-12 (listopad 2000): 1356–58. http://dx.doi.org/10.1179/026708300101507244.
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El Khessaimi, Y., Y. El Hafiane i A. Smith. "Ye’elimite synthesis by chemical routes". Journal of the European Ceramic Society 39, nr 4 (kwiecień 2019): 1683–95. http://dx.doi.org/10.1016/j.jeurceramsoc.2018.10.025.
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Hodge, Stephen A., David J. Buckley, Hin Chun Yau, Neal T. Skipper, Christopher A. Howard i Milo S. P. Shaffer. "Chemical routes to discharging graphenides". Nanoscale 9, nr 9 (2017): 3150–58. http://dx.doi.org/10.1039/c6nr10004j.
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Discharging graphenides by exposure to ambient conditions has been demonstrated to lead to a degree of oxidation. Here, effective solution phase discharging of graphenide species has been demonstrated using three different chemical agents.
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Cummins, D. "Routes to chemical plaque control". Biofouling 4, nr 1-3 (sierpień 1991): 199–207. http://dx.doi.org/10.1080/08927019109378210.
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Crespy, Daniel, Roland Hinrich Staff, Tanja Becker i Katharina Landfester. "Chemical Routes Toward Multicompartment Colloids". Macromolecular Chemistry and Physics 213, nr 12 (11.05.2012): 1183–89. http://dx.doi.org/10.1002/macp.201200124.
Pełny tekst źródłaRozprawy doktorskie na temat "Chemical routes"
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Ritchie, Robert B. "Chemical routes to atomic nitrogen". Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359346.
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Chapter 1 contains a general introduction and review of the field of atomic nitrogen chemistry. Included here is mention of the occurrences, generation, detection and analysis, reactions and uses of atomic nitrogen. A summary of previous work towards the chemical generation of atomic nitrogen in solution is given, this being stated as the overall aim of the thesis. This aim encompasses bond-breaking: (a) in nitrogen containing heterocycles upon mild photolysis or thermolysis, (b) in azidyl radicals. Chapter 2 describes the benzocinnoline N-imine system along with its isomeric 5H-dibenzo[1,2,3][d,f]triazepine with a view to the selective derivatisation of the latter. The photochemical and oxidative reactions of these systems are investigated by esr. 1H-Benzotriazole and selected derivatives are examined as triazenyl models for the triazepinyl system. Chapter 3 considers the chemistry of the 1,3,4-dioxazol-2-ones particularly the unreported 5-O-linked derivatives which are sought as possible precursors to the novel 1,3,4-dioxazolidine-2,5-diones themselves potential atomic nitrogen precursors. Chapter 4 concerns the 1,2,4-dithiazolidine-3,5-diones as potential atomic nitrogen precursors and two routes are pursued to the little reported unsubstituted parent 1,2,4-dithiazolidinedione. Chapter 5 departs from the heterocyclic theme of chapters 2-4 and considers the generation and fragmentation of the azidyl radical as a possible source of atomic nitrogen. Evidence for the production of atomic nitrogen from this radical, generated from the persulphate oxidation of azide anion, is discussed.
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Lawrence, Duncan. "Quantifying inherent safety of chemical process routes". Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/7427.
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Inherent safety is that which is intrinsic to a chemical plant. Chemical plants should be designed to be acceptably safe and it is better if this can be achieved through inherent safety, which can not be compromised, rather than engineered safety. The earlier that inherent safety is considered, the greater are the benefits. The choice of chemical route, that is the raw materials and the sequence of reactions that converts them to the desired products, is a key early design decision that influences the inherent safety of a plant. The inherent safety must be quantified in order to choose the optimum route from a number of alternatives. A trial inherent safety index has been developed for ranking alternative chemical routes by inherent safety. The physical properties of the chemicals involved, and the conditions in the reaction steps are parameters in the index calculation procedure. The index has been tested on a number of routes to methyl methacrylate (MMA). In order to verify and improve the index, a panel of experts was asked to rank the routes, and to make comments about the index and how it could be improved. This expert judgement exercise used three questionnaires and a group meeting to elicit the required information. Statistical methods were used to analyse the results from the questionnaires. The experts agreed closely among themselves on the rankings. The rankings from the trial index and the rankings from the experts matched closely. A new index was produced based on the comments of the experts and further research. The new index is more structured than the trial index, and separation and storage steps are included in addition to reaction steps. The inherent safety of the routes to MMA has been assessed with the new index. Developing a method for quantifying the inherent safety of chemical routes has proved to be a large and difficult task. Further research is needed to decide how the interactions between parameters affect the assessment of inherent safety. The ultimate goal is a computerised tool that could be used in the early stages of industrial process development.
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Tangeysh, Behzad. "SIZE-CONTROLLED SYNTHESIS OF TRANSITION METAL NANOPARTICLES THROUGH CHEMICAL AND PHOTO-CHEMICAL ROUTES". Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/327946.
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ChemistryPh.D.
The central objective of this work is developing convenient general procedures for controlling the formation and stabilization of nanoscale transition metal particles. Contemporary interest in developing alternative synthetic approaches for producing nanoparticles arises in large part from expanding applications of the nanomaterials in areas such as catalysis, electronics and medicine. This research focuses on advancing the existing nanoparticle synthetic routes by using a new class of polymer colloid materials as a chemical approach, and the laser irradiation of metal salt solution as a photo-chemical method to attain size and shape selectivity. Controlled synthesis of small metal nanoparticles with sizes ranging from 1 to 5nm is still a continuing challenge in nanomaterial synthesis. This research utilizes a new class of polymer colloid materials as nano-reactors and protective agents for controlling the formation of small transition metal nanoparticles. The polymer colloid particles were formed from cross-linking of dinegatively charged metal precursors with partially protonated poly dimethylaminoethylmethacrylate (PDMAEMA). Incorporation of [PtCl6]2- species into the colloidal particles prior to the chemical reduction was effectively employed as a new strategy for synthesis of unusually small platinum nanoparticles with narrow size distributions (1.12 ± 0.25nm). To explore the generality of this approach, in a series of proof-of-concept studies, this method was successfully employed for the synthesis of small palladium (1.4 ±0.2nm) and copper nanoparticles (1.5 ±0.6nm). The polymer colloid materials developed in this research are pH responsive, and are designed to self-assemble and/or disassemble by varying the levels of protonation of the polymer chains. This unique feature was used to tune the size of palladium nanoparticles in a small range from 1nm to 5nm. The procedure presented in this work is a new convenient room temperature route for synthesis of small nanoparticles, and its application can be extended to the formation of other transition metals and alloy nanoparticles. This research also focuses on developing new photo-chemical routes for controlling the size and shape of the nanoparticles through high-intensity ultra-fast laser irradiation of metal salt solution. One of the core objectives of this work is to explore the special capabilities of shaped laser pulses in formation of metal nanoparticles through irradiation of the solutions by using simultaneous spatial and temporal focusing (SSTF). Femtosecond laser irradiation has not yet been widely applied for nanoparticle synthesis, and offers new regimes of energy deposition for synthesis of nanomaterials. Photo-reduction of aqueous [AuCl4]- solution to the gold nanoparticles (AuNPs) has been applied as a model process for optimizing the experimental procedures, and evaluating the potential of shaped laser pulses in the synthesis of AuNPs. Systematic manipulation of the laser parameters and experimental conditions provided effective strategies to control the size of Au nanoparticles in strong laser fields. Varying the concentration of polyethylene glycol (PEG45) as a surfactant effectively tuned the size of AuNPs from 3.9 ±0.7nm to 11.0 ±2.4nm, and significantly increased the rate of Au(III) reduction during irradiation. Comparative studies revealed the capability of shaped laser pulses in the generation of smaller and more uniform AuNPs (5.8 ±1.1nm) relative to the other conventional laser irradiation methods (7.2 ±2.9nm). Furthermore, a new laser-assisted approach has been developed for selective formation of triangular Au nanoplates in the absence of any surfactant molecule. This method relies on rapid energy deposition by using shaped, ultra-intense laser pulses to generate Au seeds in aqueous [AuCl4]- solution, and the slow post-irradiation reduction of un-reacted [AuCl4]- species by using H2O2 as a mild reducing agent. Variation of the laser irradiation-time was found as an effective strategy to tune the morphology of Au nanomaterials from nanospheres to triangular nanoplates. The surfactant-free Au nanoplates produced in this research can be readily functionalized with a variety of target molecules or surfactants for desirable applications such as biomedicine. The concept of rapid laser processing followed by in situ chemical reduction can be expanded as a general methodology for high-yield production of nanomaterials, and provides a series of new laser dependent parameters for controlling the nanoparticle formation.
Temple University--Theses
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Grimsdale, Andrew Clive. "Routes to drimanes from podocarpic acid". Thesis, University of Auckland, 1989. http://hdl.handle.net/2292/2072.
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The synthesis and ozonolysis of the 6- and 7-substituted 12-hydroxypodocarpatrienes (26), (86), (90), and (98), as a possible route for the synthesis of drimanes from 12-hydroxypodocarpa-8,11,13-trien-19-oic acid (podocarpic acid) (9) has been investigated. Modification of the aromatic ring of (9) has given 11- and l4-hydroxypodocarpatrienes which were ozonised to give the congeners (31), (34), and (36) of the naturally occurring drimanes confertifolin (6), isodrimenin (7), and winterin (8). The oxidation of a 12,13-dihydroxypodocarpatriene (37) and its dimethyl ether (38) have also been investigated. Routes for the conversion of the enone (45) and oxime (230), derived from the ozonolysis products of methyl podocarpate (10), to drimanes have also been investigated.
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Cayado, Llosa Pablo. "Multifunctional nanostructured superconductors by chemical routes: towards high current conductors". Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/384856.
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Uno de los temas de mayor interés en el ámbito de la superconductividad es la fabricación de cintas superconductoras (CCs) de YBa2Cu3O6+δ (YBCO) debido a las excelentes propiedades superconductoras que poseen y a las prometedoras perspectivas en cuanto a aplicaciones se refiere. Sin embargo, para poder generalizar el uso de dichas CCs, se requiere de un proceso de fabricación de bajo coste. En este contexto, la técnica de deposición por solución química se presenta como una alternativa muy prometedora. Las CCs pueden cumplir los requisitos actuales exigidos en diferentes aplicaciones, pero hay otras que están fuera de sus capacidades, especialmente aquellas relacionadas con aplicaciones de potencia en las que están presentes campos magnéticos de gran intensidad. El movimiento de los vórtices que tienes lugar en presencia de tales campos magnéticos hace que el YBCO sea poco efectivo en estos casos. El objetivo de este trabajo es mejorar las propiedades del YBCO de manera que se puedan satisfacer los requerimientos de estas aplicaciones de potencia. Para ello, hemos estudiado, principalmente, dos estrategias: la nanoestructuración de la matriz del YBCO añadiendo nanopartículas (NPs) obteniendo nanocomposites superconductores y la optimización del proceso de oxigenación del YBCO para conseguir aumentar todo lo posible la temperatura crítica y la densidad de corriente crítica. La preparación de los nanocomposites de YBCO se llevó a cabo siguiendo dos métodos diferentes de “deposición y crecimiento secuencial”: el método “in-situ” en el que las NPs se forman de manera espontánea durante el proceso de crecimiento, y el método “ex-situ”, que es un novedoso procedimiento desarrollado durante esta tesis en el cual las NPs se sintetizan primeramente formando una solución coloidal para luego quedar atrapadas en la matriz del YBCO durante los procesos térmicos. El uso del método “in-situ” se ha enfocado al estudio de como diferentes NPs (BaZrO3, Y2O3, Ba2YTaO6 and mezclas de éstas) afectan la microestructura del YBCO creando defectos cristalinos que incrementan la fuerza de anclaje. Hemos estudiado también la influencia de estos defectos, en particular, de las dobles cadenas Cu-O, en las propiedades finales de los nanocomposites de YBCO y GdBCO. En el caso del método “ex-situ”, el primer paso fue sintetizar diferentes soluciones coloidales de NPs magnéticas (MnFe2O4 and CoFe2O4) y no magnéticas (CeO2 and ZrO2). Se comprobó la estabilidad de las soluciones YBCO+NPs mediante medidas de DLS y de TEM para asegurar que las NPs conservaban su tamaño inicial sin formar aglomerados. El proceso de pirólisis fue optimizado para cada tipo de NPs teniendo en cuenta que los ligandos usados para estabilizar las NPs pueden influenciar de manera drástica la homogeneidad de las capas pirolizadas. Por último, el proceso de crecimiento fue también investigado para cada tipo de NPs. El estudio del proceso de oxigenación en la capas de YBCO se llevó a cabo usando medidas de resistencia “in-situ”, que permiten monitorizar la evolución de la resistencia en las capas durante los distintos procesos térmicos. Hemos estudiado como la temperatura, el flujo de gas y la presión parcial de oxigeno afectaba al proceso de difusión. De acuerdo con nuestros resultados, las reacciones que tienen lugar en la superficie de la capa antes de que en oxígeno se difunda en el interior de la misma, son el factor que limita la cinética del proceso de oxigenación. Por último El efecto de la adición de plata como catalizador y la difusión en nanocomposites también se ha estudiado.One of the hot topics in the field of superconductivity is the YBa2Cu3O6+δ (YBCO) Coated Conductors (CCs) fabrication due to the excellent superconducting properties and promising application prospects. However, in order to spread worldwide the use of YBCO coated conductors, a low cost fabrication is required. Chemical Solution Deposition has emerged as a promising alternative that can accomplish this requirement. Despite that YBCO CCs can satisfy the requirements in many different applications, the fact is that there are other uses that are out of it reach with its current status, especially those power applications in which high magnetic fields are applied. The vortex movement which takes place at such high magnetic fields makes YBCO CCs useless for these particular applications. The aim of this work is to improve the properties of YBCO satisfying the demands of these power applications. For this, we studied, mainly, two different strategies: nanostructuration of the original YBCO matrix by adding NPs (superconducting nanocomposites) and optimization of the YBCO oxygenation process to enhance as much as possible the critical temperature and critical current density. The preparation of YBCO nanocomposites was done following two different “Sequential deposition and growth” approaches: the in-situ approach in which the NPs are spontaneously segregated during the growth process; and the ex-situ approach, a new methodology developed in this thesis in which the NPs are firstly synthesized in a colloidal solution and then embedded in the YBCO matrix. Using the in-situ approach we have made an extensive study of how different NPs (BaZrO3, Y2O3, Ba2YTaO6 and mixtures of these) affect the microstructure of the YBCO creating defects that increase the pinning properties. We have also studied the influence of these defects, in particular, the stacking faults (double chains of Cu-O), on the final properties of the YBCO and GdBCO nanocomposites. With the ex-situ approach we have started by synthesizing different colloidal solutions of both magnetic (CoFe2O4) and non-magnetic (CeO2 and ZrO2) NPs. The stability of YBCO+NPs solutions was checked using TEM and DLS analyses to ensure that the NPs are maintaining the initial size without forming agglomerates. The pyrolysis process was optimized for each type of NPs. We realized that the stabilization agents can critically influence the homogeneity of the pyrolyzed films. Finally, the growth process was also optimized for each type of NPs trying to solve different difficulties that appeared: coarsening, pushing or reactivity. The study of the oxygen diffusion process in YBCO thin films was done using in-situ resistivity measurements that allow to monitor the evolution of the resistance in the thin films in different annealing conditions. We have studied how the temperature, the gas flow and the oxygen partial pressure affect the diffusion process. According to our results, we can conclude that the surface reactions that take place before the oxygen bulk diffusion is the limiting factor for the oxygen diffusion. The effect of the silver addition to the YBCO as oxygen catalyst was also tested. Finally, the first study about the oxygen diffusion process in nanocomposite films gave an idea of how the oxygen diffusion works in this kind of materials.
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Bond, Stuary Grahame. "Routes to reactive oligomers involving photochemical and chemical cleavage of copolymers". Thesis, Lancaster University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315936.
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Wernet, Judith Hedwig. "Composite and microcomposite fabrication via depletion stabilization routes". Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1061910390.
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Green, Mark A. "Novel routes to nanodispersed semiconductors". Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/12035.
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Karlsson, Johan. "Theoretical Routes for c-BN Thin Film Growth". Doctoral thesis, Uppsala universitet, Oorganisk kemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-191181.
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c-BN has been in focus for several years due to its interesting properties. The possibility for large area CVD is a requirement for the realization of these different properties in various applications. Unfortunately, there are at present severe problems in the CVD growth of c-BN. The purpose with this research project has been to theoretically investigate, using DFT calculations, the possibility for a layer-by-layer CVD growth of c-BN. It could be established that, PEALD, using a BF3-H2-NH3-F2 pulse cycle and a diamond substrate, is a promising method for deposition of c-BN films. The gaseous species will decompose in the plasma and form BFx, H, NHx, and F species (x = 0, 1, 2, 3). The H and F radicals will uphold the cubic structure by completely hydrogenate, or fluorinate, the growing surface. However, surface radical sites will appear during the growth process as a result of atomic H, or F, abstraction reactions. The addition of NHx growth species (x = 0, 1, 2) to B radical sites, and BFx growth species (x = 0, 1, 2) to N radical sites, will then result in a continuous growth of c-BN.
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Sandberg, Birgersson Paulina. "Transparent paper: Evaluation of chemical modification routes to achieve self-fibrillating fibres". Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-281347.
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Transparenta papper tillverkade av cellulosa nanofibriller (CNF), visar stor potential att kunna ersätta petroleumbaserade plaster inom många användningsområden, till exempel för mat- och varuförpackningar. CNF, även känt som nanocellulosa, kombinerar viktiga cellulosaegenskaper, med unika egenskaper hos nanomaterial. Denna kombination av egenskaper möjliggör tillverkning av ett pappers-liknande material som uppvisar både utmärkta mekaniska egenskaper och hög transparens. Användningen av nanocellulosa är dock förknippad med diverse utmaningar, för att materialet ska kunna bli kommersiellt slagkraftigt. En av de främsta utmaningarna är nanocellulosas höga affinitet för vatten och dess höga specifika yta som försvårar hanteringen av materialet. Avvattningen av nanocellulosadispersioner, för att tillverka transparenta papper, kan ta upp till flera timmar. För att övervinna detta hinder, har avdelningen för Fiberteknologi vid KTH tillsammans med BillerudKorsnäs AB, nyligen utvecklat en metodik för att skapa så kallade själv-fibrillerande fibrer (SFFer). Dessa fibrer möjliggör en snabbavvattnad papperstillverkningsprocess med makroskopiska vedbaserade fibrer, som efter tillverkning av pappret omvandlas till ett nanocellulosapapper, det vill säga ett nanopapper. För att erhålla SFFer krävs det att höga koncentrationer av karboxyl- och aldehydgrupper introduceras i cellulosafibrerna. Införandet av dessa funktionella grupper, möjliggör självfibrilleringen då SFFerna utsätts för moderata alkali-koncentrationer. I den ursprungliga studien som utfördes av Gorur m.fl., introducerades de funktionella grupperna med hjälp av sekventiell TEMPO- och periodatoxidation. I detta examensarbete, har alternativa kemiska metoder för att introducera samma kemiska funktionalitet som TEMPO-periodatsystemet undersökts. Huvudsyftet med arbetet är att besvara frågan: Hur påverkar olika kemiska behandlingar vid SFF tillverkningen, de kemiska och fysikaliska egenskaperna hos de modifierade fibrerna, samt de slutgiltiga pappersegenskaperna? För att besvara frågan, preparerades fibrer med liknande karboxyl- och aldehydinnehåll med hjälp av följande tre kemiska metoder: 1) TEMPO- följd av periodatoxidation (detta kommer att användas som referenssystem); 2) periodat- följd av kloritoxidation; 3) karboxymetylering följd av periodatoxidation. Egenskaperna hos fibrerna undersöktes med avseende på aldehyd- och karboxylinnehåll, avvattningspotential och förmåga att självfibrillera. Papper tillverkades med hjälp av en vakuumfiltreringsuppställning och följande egenskaper undersöktes hos pappret: mekaniska egenskaper (dragstyrka, brottsyrka och Young’s modul); optiska (transparens och ytreflektion); samt syrgaspermeabilitet. De erhållna fibrerna från samtliga tre kemiska modifieringar visade på självfibrillerande egenskaper i alkaliska lösningar. Detta beteende styrker hypotesen att ett strategiskt införande av ett högt karboxyl- och aldehydinnehåll leder till självfibrillerande fibrer. Transparenta papper tillverkade av fibrer som utsatts för TEMPO-periodatoxidation samt klorit-periodatoxidation, visade på utmärkta mekaniska egenskaper, hög transparens och bra barriäregenskaper - jämförbara med vad som vanligen kan noteras hos papper tillverkat av nanocellulosa. Samtliga egenskaper förbättrades ytterligare efter fibrillering av fibrerna i papperen. De karboxymetylerade-periodatoxiderade materialet, å andra sidan, uppvisade andra egenskaper jämfört med de två, tidigare nämnda, metoderna. TEMPO-periodat- och periodat-klorit-pappersmassan var halvgenomskinlig och geléliknande, medan den karboxymetylerade-periodatoxiderade massan var mer lik det omodifierade materialet. Detsamma gällde det tillverkade pappret som liknade ett konventionellt papper. Det var inte heller möjligt att åstadkomma en fibrillering av det karboxymetylerade-periodatoxiderade-pappret som utsattes för behandling med alkaliska lösningar. Avvattningstiden vid papperstillverkningen varierad mellan 4 och 60 sekunder, och karboxymetylering-periodat oxidation visade på snabbast avvattningstid. Den förlängda avvattningstiden i jämförelse med studien utförd av Gorur m.fl., tros främst bero på att ett filtreringsmembran med mindre porer användes på vakuumfiltreringsuppställningen, istället för en avvattningsvira som tidigare använts. Sammanfattningsvis så har det visat sig möjligt att tillverka självfibrillerande fibrer med hjälp av samtliga tre undersökta kemiska modifieringar. SFFer möjliggör tillverkning av snabbavvattnade transparenta nanocellulosapapper och visar på så vis på hög potential att kunna ersätta olje-baserade plaster till många förpackningsapplikationer.Transparent papers made from cellulose nanofibrils (CNF), derived from e.g. wood, show great potential to replace petroleum-based plastics in many application areas, such as packaging for foods and goods. CNF, also known as nanocellulose, combine important cellulose properties with the unique features of nanoscale materials, gaining paper-like materials with outstanding mechanical properties and high transparency. However, nanocellulose faces various challenges in order to make the products commercially competitive. One of the main challenges is accompanied with nanocelluloses’ high affinity for water, which makes processing difficult. Dewatering of a nanocellulose dispersion in order to produce transparent paper may take up to several hours. To overcome this obstacle, the Fibre technology division at KTH Royal Institute of technology and BillerudKorsnäs AB have recently developed a new concept of self-fibrillating fibres (SFFs). This material enables fast-dewatering papermaking using fibres of native dimensions and conversion into nanocellulose after the paper has been prepared. In order to obtain SFFs, proper amounts of charged groups and aldehyde groups need to be introduced into the cellulose backbone. When SFFs are exposed to high alkali concentration, i.e. > pH=10, the fibres self-fibrillates into CNFs. In the original study, the functional groups were introduced through sequential TEMPO oxidation and periodate oxidation. In this work, alternative chemical routes have been examined to prepare SFFs with the same functional groups as introduced with the TEMPO-periodate system. The aim of the thesis has been to answer: how does different chemical routes to prepare transparent nanopaper made from SFFs affect the chemical and physical properties of the modified fibres, as well as the final physical properties of the transparent papers? To answer the question, fibres with similar carboxyl and aldehyde contents were prepared using three chemical routes: 1) TEMPO oxidation followed by periodate oxidation (which was used as reference system); 2) periodate oxidation followed by chlorite oxidation; 3) carboxymethylation followed by periodate oxidation. The properties of the fibres were examined regarding aldehyde and carboxyl content, dewatering potential and self-fibrillating ability. Papers were produced using a vacuum filtration set-up and the properties investigated were the mechanical; tensile strength, strain at failure and Young’s modulus, the optical properties; transparency and haze, as well as the oxygen permeability. In order to investigate the impact of the fibrillation of the papers, the properties were measured for both unfibrillated and fibrillated samples. Furthermore, the gravimetric yield after each chemical modification procedure was examined, as well as the dewatering time during sheet making. Fibres obtained from all three chemistries demonstrated self-fibrillating properties in alkaline solutions. This strengthens the hypothesis that the strategical introduction of aldehydes and carboxyl groups is the main feature responsible for the self-fibrillating ability of the fibres. Transparent papers made from fibres treated through TEMPO-periodate oxidation and periodate-chlorite oxidation showed excellent mechanical, optical and barrier properties, comparable to those seen in nanocellulose papers. The properties were further increased after fibrillation. The carboxymethylated-periodate oxidized fibres, on the other hand, behaved differently from the others. While the TEMPO-periodate and periodate-chlorite pulp was semi-translucent and gel-like, the carboxymethylated-periodate oxidized fibres resembled more the unmodified material. Likewise, the properties of those papers resembled conventional paper and no fibrillationwas experienced after immersing the papers in alkaline solution, according to the same protocol developed for the other two chemistries. The dewatering time during sheet making ranged from 4–60 seconds (carboxymethylation-periodate oxidation showing the fastest dewatering rates). The increased dewatering time compared to earlier studies is believed to mainly be due to the use of a filtration membrane on the vacuum filtration set-up, instead of a metallic wire with larger pores. Overall, SFFs was successfully produced using three different chemical routes. SFFs enables production of fast-dewatering transparent nanocellulose papers that shows the potential to replace oil-based plastics in many packaging applications.
Książki na temat "Chemical routes"
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L, Davidson Robert, red. Computer-aided chemistry: New routes to tomorrow's drugs and chemicals. Fort Lee, N.J: Technical Insights, 1986.
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1949-, Schreier Hans, red. Drug targeting technology: Physical, chemical, biological methods. New York: Marcel Dekker, 2001.
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Inc, Technical Insights, red. Advances in bioprocess technology: Industrial/specialty chemicals via biological sources/routes. Fort Lee, NJ: Technical Insights, 1985.
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1935-, Rouxel Jean, Tournoux M i Brec R, red. Soft chemistry routes to new materials: Chimie douce : proceedings of the international symposium held in Nantes, France, September 6-10, 1993. Aedermannsdorf, Switzerland: Trans Tech Publications, 1994.
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Blay, Vincent, Luis Francisco Bobadilla i Alejandro Cabrera, red. Zeolites and Metal-Organic Frameworks. NL Amsterdam: Amsterdam University Press, 2018. http://dx.doi.org/10.5117/9789462985568.
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Zeolites are natural or synthetic materials with porous chemical structures that are valuable due to their absorptive and catalytic qualities. Metal-Organic Frameworks (MOFs) are manmade organometallic polymers with similar porous structures. This introductory book, with contributions from top-class researchers from all around the world, examines these materials and explains the different synthetic routes available to prepare zeolites and MOFs. The book also highlights how the substances are similar yet different and how they are used by science and industry in situations ranging from fueling cars to producing drugs.
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Small, C. M. ZnO ceramic varistors prepared by a chemical route. Manchester: UMIST, 1995.
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Canada, Canada Environment, i Canada Environmental Protection Service, red. Roadsalts: Code of practice for the environmental management of road salts. [Ottawa]: Environment Canada, 2004.
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Lawrence, Duncan. Quantifying inherent safety of chemical process routes. 1996.
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Schreier, Hans. Drug Targeting Technology: Physical Chemical Biological Methods. Taylor & Francis Group, 2001.
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Schreier, Hans. Drug Targeting Technology: Physical Chemical Biological Methods. Taylor & Francis Group, 2001.
Znajdź pełny tekst źródłaCzęści książek na temat "Chemical routes"
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Forrester, A. R., H. Irikawa, M. Passway, R. Ritchie i K. Tucker. "Chemical Routes to Atomic Nitrogen". W Organic Free Radicals, 61–62. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-73963-7_31.
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Hocking, M. B. "Industrial Bases by Chemical Routes". W Modern Chemical Technology and Emission Control, 122–33. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-69773-9_5.
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Milagres, Adriane M. F., Walter Carvalho i Andre Ferraz. "Topochemistry, Porosity and Chemical Composition Affecting Enzymatic Hydrolysis of Lignocellulosic Materials". W Routes to Cellulosic Ethanol, 53–72. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-0-387-92740-4_5.
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Schmidt, H. K. "Chemical Routes to Nanostructured Ceramics and Composites". W Applications of Organometallic Chemistry in the Preparation and Processing of Advanced Materials, 47–67. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0337-4_3.
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Segal, D. L. "Chemical Routes for the Preparation of Powders". W The Physics and Chemistry of Carbides, Nitrides and Borides, 3–11. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2101-6_1.
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Gupta, Nidhi, Omita Nanda, Pramod Kumar, V. K. Jain i Kanchan Saxena. "Synthesis of Zinc Oxide Nanostructures by Chemical Routes". W Physics of Semiconductor Devices, 641–43. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-03002-9_163.
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Nogales Delgado, Sergio, Carmen María Álvez Medina i Juan Félix González González. "Chemical Routes to Produce Biolubricants. The Role of Biorefineries". W SpringerBriefs in Applied Sciences and Technology, 35–54. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-65644-6_4.
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Gupta, Neeta, Arti Hadap i Bhawana Jain. "Synthesis of Nanomaterials via Physical, Chemical, and Biological Routes". W Bionanotechnology for Advanced Applications, 29–50. New York: CRC Press, 2024. http://dx.doi.org/10.1201/9781003362258-4.
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Patel, Ramesh N. "Biocatalytic Routes to Chiral Intermediates for Development of Drugs". W Biocatalysis for Green Chemistry and Chemical Process Development, 89–149. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118028308.ch5.
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Torres, E. M. Farfan, P. Grange i B. Delmon. "New routes to the preparation of pillared montmorillonite catalysts by intercalation of niobium coordinated complexes". W Chemical Physics of Intercalation, 489–95. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4757-9649-0_43.
Pełny tekst źródłaStreszczenia konferencji na temat "Chemical routes"
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Hattendorf, Heike, Chrétien G. M. Hermse i Werner Hannig. "The Influence of Production Routes on the Metal Dusting Behavior of UNS N06025 Plate, Strip and Tube". W CORROSION 2012, 1–15. NACE International, 2012. https://doi.org/10.5006/c2012-01240.
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Abstract It is generally known that the production route influences the sensitivity of a material to metal dusting. In this study the different production states of UNS N06025 are compared as there are: plate deeply ground and 600 grit laboratory ground, strip as-delivered and 600 grit laboratory ground, and longitudinally welded tubes as-delivered and 600 grit laboratory ground. All samples were exposed for 7750 hours at 600°C in a 37% CO, 7% CO2, 46% H2, 9% H2O atmosphere, Ptot = 20 bar. The differences between the samples originating from different production routes, in terms of mass loss, pit density, pit size and pit depth, are discussed in terms of the effect of surface treatment (ground, brushed, annealed, pickled), grain size, chemical composition and sample thickness.
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Estievenart, C., N. Kohler, F. Ropital i C. Fiaud. "Polyaspartates: Influence of Synthetic Routes on Scale Inhibition and Biodegradability". W CORROSION 2002, 1–19. NACE International, 2002. https://doi.org/10.5006/c2002-02412.
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Abstract Calcium carbonate scale deposition is a major problem in industrial cooling systems. In most cases it reduces the overall flow rate, limits thermal exchanges and in some cases may even lead to a complete shutdown of the installations. Various chemical additives have been proposed to inhibit scale deposits. Due to more and more severe ecological constraints, the use of biodegradable inhibitors has some promising prospects. Polyaspartate as a green scale inhibitor can be prepared by different synthetic routes. Preparation conditions influence both scale inhibition efficiency and biodegradability. Scale inhibition is evaluated by the EQCM method under different dynamic conditions in waters of different characteristics. Biodegradability is analysed by the respiration of biomass in the presence of polyaspartates. Links for preparation of efficient green inhibitors were thus obtained. The more biodegradable and the best scale inhibiting polyaspartates are synthesised by bulk polycondensation in mixed solvents with catalyst. All scaling tests performed in the presence of polyaspartates develop the vaterite morphology form of calcium carbonate.
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Perez, David, John D. Chea, Jose D. Hernandez-Betancur i Gerardo J. Ruiz-Mercado. "Life Cycle and Sustainability Analyses for Designing Chemical Circular Economy". W Foundations of Computer-Aided Process Design, 60–66. Hamilton, Canada: PSE Press, 2024. http://dx.doi.org/10.69997/sct.184280.
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Sustainability and circular economy enclose initiatives to achieve economic systems and industrial value chains by improving resource use, productivity, reuse, recycling, pollution prevention, and minimizing disposed material. However, shifting from the traditional linear economic production system to a circular economy is challenging. One of the most significant hurdles is the absence of sustainable end-of-life (EoL)/manufacturing loops for recycling and recovering material while minimizing negative impacts on human health and the environment. Overcoming these challenges is critical in returning materials to upstream life cycle stage facilities such as manufacturing. Chemical flow analysis (CFA), sustainability evaluation, and process systems engineering (PSE) can supply chemical products and processes performances from environmental, economic, material efficiency, energy footprint, and technology perspectives. These holistic evaluation techniques can improve productivity, source material reduction, reuse, recycling, and prevent and minimize releases and disposal rates. Therefore, this contribution offers a computational framework that covers CFA, sustainability assessment, and risk evaluation for quantifying the benefits and challenges of chemical circular economy routes versus conventional linear systems. Finally, this contribution shows promising techniques and challenges for employing CFA, sustainability evaluation, and PSE as multicriteria decision-making tools for designing a closed-loop chemical management infrastructure and transforming the US chemical industry sector from linear to circular.
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Wen, Ching-Mei, Charles Foster i Marianthi Ierapetritou. "Exploring Net-Zero Greenhouse Gas Emission Routes for Bio-Production of Triacetic Acid Lactone: An Evaluation through Techno-Economic Analysis and Life Cycle Assessment". W Foundations of Computer-Aided Process Design, 933–40. Hamilton, Canada: PSE Press, 2024. http://dx.doi.org/10.69997/sct.182968.
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Triacetic acid lactone (TAL) is a bio-privileged molecule with potential as a chemical precursor, traditionally synthesized from petroleum. Current trends are shifting towards the use of renewable biomass or CO2-derived feedstocks to enhance sustainability. However, comprehensive studies on the techno-economic viability and carbon life cycle of such methods are limited. This study assesses TAL production from conventional glucose and a novel approach co-feeding Yarrowia lipolytica (YL) with glucose and formic acid (FA), aiming for a more cost-effective and eco-friendly process. We confront the inherent challenges in this process by exploring different technology scenarios using kinetic bioprocess modeling underpinned by techno-economic analysis (TEA) and life cycle assessment (LCA) to identify the most cost-effective and sustainable routes to TAL production. A noteworthy component of our investigation centers around the prospect of recycling and utilizing the CO2 emitted from the YL bioreactor to eliminate greenhouse gas emissions inherent in aerobic fermentation processes. The study combines TEA and LCA to dissect the proposed TAL bio-production routes, evaluating the sustainability of the process and the implications of net-zero greenhouse gas emission manufacturing. We employed SuperPro Designer and Aspen software for process simulation and energy balance computations. The results underscore the benefits of CO2 recycling in TAL production, with an estimated minimum selling price (MSP) slightly increasing by 6.21-7.80% compared to traditional methods, but significantly undercutting the market price of $51000/mt-TAL and achieving net-negative CO2 emissions. This research illustrates a viable route to bio-production with net-zero emissions, providing a model for future bioprocessing and industrial practices.
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Reid, Kim R., Ari Lewis, Rosemary Mattuck i Michael Peterson. "Warning! Technical Challenges of Compliance with the New Proposition 65 Regulations". W Coatings+ 2019, 1–7. SSPC, 2019. https://doi.org/10.5006/s2019-00043.
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Abstract Compliance with California's Prop 65 regulations have become even more complicated since the new Clear and Reasonable Warning labeling rules took effect on August 30, 2018. These changes are a definite game changer. With this legal imperative, companies selling products in California may need to consider specific and proactive compliance strategies to address the various implications of the rule. In particular, the new warning labels will be required to list at least one chemical that prompted the warning, along with its associated health effects. Additionally, compliance with the rules may pose some significant technical challenges for companies. Some of the more significant issues relate to identifying and testing for chemicals in products for relevant routes of exposure for both workers and consumers, quantifying exposure under many different scenarios, and developing specific Safe Harbor Levels for Prop 65-listed chemicals that do not currently have them established. This presentation will provide a brief overview of the recent Prop 65 changes and will explore some of the legal consequences associated with noncompliance. We will also present some critical technical considerations and strategies involved in ensuring compliance with Prop 65. Methodologies for designing a robust analytical testing program as well as technical approaches for toxicological and exposure evaluations will be presented, along with several focused case examples.
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Kirchheiner, Rolf, i Georg-Wilhelm Overbeck. "Development of High Performance Cast Alloys Alloy 31 and Alloy 59 for the Chemical Process Industry". W CORROSION 2007, 1–13. NACE International, 2007. https://doi.org/10.5006/c2007-07187.
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Abstract Within the last decades great efforts were made by the producers of wrought corrosion resistant products to develop new alloys. The materials of construction for modern chemical process industry (CPI) plants, petrochemical and other industries not only have to resist uniform corrosion. New alloys must also have sufficient resistance against localized corrosion and stress corrosion cracking. These industries have to cope with both the technical and commercial challenges of rigid environmental regulations, the need to increase production efficiency, and at the same time possess the necessary versatility to handle varied feed stock and upset conditions.(1) Due to the production routes in all these companies, they concentrated on their standard products like plate, bar, wire and tube. All plants in the chemical process industries however also need castings for pumps and valves in the piping systems, connecting reactors and heat exchangers. In the past, only few foundries copied the analysis of the new materials, aiming at the production of castings similar in corrosion resistance to the wrought alloys. Prominent examples of highly corrosion resistant materials are Alloy 59 (UNS 06059) and Alloy 31 (UNS 08031) developed in wrought product forms, e. g. sheet, plate, strip and forging, in Germany. Some years ago, a German foundry obtained a license to produce cast versions of these alloys with the obligation to execute extensive testing of corrosion resistance and mechanical properties in direct comparison with the wrought materials. This paper reports the results of these efforts in some very corrosive media which are used in chemical plants. The tests were executed in the corrosion laboratories of an internationally acknowledged chemical enterprise.
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Johnston, S. L., G. Cunningham, G. Voordouw i T. R. Jack. "Sulfur-Reducing Bacteria May Lower Corrosion Risk in Oil Fields by Coupling Oxidation of Oil Organics to Reduction of Sulfur-Polysulfide to Sulfide". W CORROSION 2010, 1–11. NACE International, 2010. https://doi.org/10.5006/c2010-10254.
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Abstract Sulfate-reducing bacteria are generally considered to have a profound impact on the petroleum industry as their sulfide production activity contributes to reservoir souring and pipeline corrosion. SRB can be controlled by injecting biocides into pipelines and above-ground facilities. A recent “green” alternative for controlling reservoir souring is to inject nitrate, as nitrate is relatively harmless and is ultimately reduced to nitrogen gas. Resident nitrate-reducing bacteria (NRB) reduce nitrate to nitrite, which is a strong inhibitor of SRB, thereby inhibiting sulfide production. However, NRB-mediated oxidation of sulfide with nitrate and/or chemical reaction between nitrite and sulfide can generate sulfur-polysulfide (S-PS), which can expedite corrosion. S-PS is also rapidly formed by chemical reactions, when sour produced waters, containing substantial sulfide concentrations, are exposed to air. Once formed, S-PS can be removed by either of two alternative routes, which may thus reduce corrosion risk. In the presence of (i) excess electron acceptor (e.g. nitrate), NRB may further oxidize the S-PS to sulfate, whereas in the presence of (ii) excess electron donor (oil organics, e.g. acetate) the S-PS may be reduced back to sulfide. A specialized group of sulfur-reducing bacteria catalyzes this reaction. A representative of this group, Desulfuromonas acetoxidans, derives energy for growth from the reaction: 4 sulfur + acetate = 4 sulfide + 2 CO2. Because oil field waters tend to be electron donor rich and electron acceptor poor, one would expect S-PS to be removed by the second route. A survey of the microbial community in produced waters from an oil field with low bottomhole temperatures indicated Desulfuromonas species to be common. Hence, once S-PS is formed by reaction of excess sulfide with a limiting concentration of nitrate or oxygen, it may subsequently be effectively removed through the activity of sulfur-reducing bacteria such as Desulfuromonas.
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Salazar, César A., Rafael Colás, Miguel A. Quiñones, Luis E. Hernández i Imre Felde. "Characterization of Advanced High-Strength Steels by Mechanical Testing and Fracture Analysis". W IFHTSE 2024, 346–51. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.ifhtse2024p0346.
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Abstract The automotive industry has searched for alternatives to reduce the weight of vehicles without neglecting the user’s safety by using new materials. Advanced high-strength steels of complex phases are used in structural applications requiring good performance and reducing the weight of vehicles. However, these steels have shown edge cracking, known as fissure, during processing, which has become a challenge for steelmakers and other companies that rely on them to manufacture structural components. Such defects can be associated with the interaction between the different microstructural constituents of the steel, such as various phases and precipitates generated during its processing to achieve the required mechanical properties. The present work presents the studies evaluate the effect that processing and chemical composition exerts on edge cracking in complex phase steels of grade 800 MPa produced by different steelmaking routes.
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Erriquez, Eleonora, Francesco Crisafi, Andrea Ragni, Federico Monti, Gabriele Di Noia, Mujeeb Rahman, Tiago Azevedo i in. "Multiplex stimulated Raman histology: a route towards the application to the clinical routine". W Advanced Chemical Microscopy for Life Science and Translational Medicine 2025, redaktorzy Garth J. Simpson, Ji-Xin Cheng i Wei Min, 54. SPIE, 2025. https://doi.org/10.1117/12.3043003.
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Ho, Clifford K. "Stochastic Modeling of Chemical Transport Through Human Skin". W ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-42907.
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A probabilistic, transient, three-phase model of chemical transport through human skin has been developed to assess the relative importance of uncertain parameters and processes during chemical exposure assessments and transdermal drug delivery. Penetration routes through the skin that were modeled include the following: (1) intercellular diffusion through the multiphase stratum corneum; (2) aqueous-phase diffusion through sweat ducts; and (3) oil-phase diffusion through hair follicles. Uncertainty distributions were developed for the model parameters, and a Monte Carlo analysis was performed to simulate probability distributions of mass fluxes through each of the routes for a hypothetical scenario of chemical transport through the skin. At early times (60 seconds), the sweat ducts provided a significant amount of simulated mass flux into the bloodstream. At longer times (1 hour), diffusion through the stratum corneum became important because of its relatively large surface area. Sensitivity analyses using stepwise linear regression were also performed to identify model parameters that were most important to the simulated mass fluxes at different times.
Raporty organizacyjne na temat "Chemical routes"
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Schaak, Raymond E. Chemical Routes to Colloidal Chalcogenide Nanosheets. Office of Scientific and Technical Information (OSTI), listopad 2014. http://dx.doi.org/10.2172/1170371.
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Sneddon, Larry G. Chemical Precursor Routes to Ceramic Nanocylinders. Fort Belvoir, VA: Defense Technical Information Center, czerwiec 2003. http://dx.doi.org/10.21236/ada416277.
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Sneddon, Larry G., i Shu Yang. Chemical Routes to Ceramics with Tunable Properties and Structures: Chemical Routes to Nano and Micro-Structured Ceramics. Fort Belvoir, VA: Defense Technical Information Center, grudzień 2009. http://dx.doi.org/10.21236/ada589781.
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Sneddon, Larry G. Chemical Routes to Ceramics With Tunable Properties and Structures. Fort Belvoir, VA: Defense Technical Information Center, lipiec 2006. http://dx.doi.org/10.21236/ada455765.
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Sariciftci, Niyazi Serdar. CO2 Recycling: The Conversion of Renewable Energy into Chemical Fuels. AsiaChem Magazine, listopad 2020. http://dx.doi.org/10.51167/acm00011.
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We want to bring the idea of conversion of CO2 into synthetic fuels (CO2 recycling) into attention, as a possible approach for transportable storage of renewable energy. Recycling of CO2 by homogeneous and/or heterogeneous catalytic approaches have been investigated with increasing emphasis within the scientific community. In the last decades, especially using organic and bioorganic systems towards CO2 reduction has attracted great interest. Chemical, electrochemical, photoelectrochemical, and bioelectrochemical approaches are discussed vividly as new routes towards the conversion of CO2 into synthetic fuels and/or useful chemicals in the recent literature. Here we want to especially emphasize the new developments in bio-electrocatalysis with some recent examples.
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Jamison, G. M., D. A. Loy i J. G. Curro. LDRD final report on chemical functionalization of oligo(hydrido)silanes, economically attractive routes to new photoresponsive materials. Office of Scientific and Technical Information (OSTI), maj 1997. http://dx.doi.org/10.2172/491421.
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Phillips, Donald A., Yitzhak Spiegel i Howard Ferris. Optimizing nematode management by defining natural chemical bases of behavior. United States Department of Agriculture, listopad 2006. http://dx.doi.org/10.32747/2006.7587234.bard.
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This project was based on the hypothesis that nematodes interacting with plants as either parasites or beneficial saprophytes are attracted to their host by natural products. This concept was supported by numerous observations that parasitic nematodes are attracted to root exudates. Our overall goal was to identify nematode sensory compounds from root exudates and to use that information for reducing nematicide applications. We applied skills of the investigators to achieve three specific objectives: 1) Identify nematode behavioral cues (e.g., attractants or repellents) in root exudates; 2) Identify new natural nematicidal compounds; and 3) Combine a natural attractant and a nematicide into a nematode trap. Because saprophytic nematodes benefit plants by mineralizing organic matter, we sought compounds attractive primarily to parasitic nematodes. The project was constructed on several complementary foundations. First, data from Dr. Spiegel’s lab showed that under aseptic conditions Ditylenchus dipsaci, a parasite on onion, is attracted to certain fractions of onion root exudates. Second, PI Phillips had a sizeable collection of natural plant products he had identified from previous work on Rhizobium-legume interactions, which could be tested “off the shelf”. Third, Dr. Ferris had access to aseptic and natural populations of various saprophytic and parasitic nematodes. The project focused on five nematode species: D.dipsaci, Heterodera avenae, and Tylenchulussemipenetransat ARO, and Meloidogyne javanicand Caenorhabditis elegans at UCD. Ten pure plant compounds, mostly flavonoids, were tested on the various nematode species using six different assay systems. Results obtained with assorted test systems and by various scientists in the same test systems were essentially irreproducible. Many convincing, Many convincing, i.e. statistically significant, results in one system or with one investigator could not be repeated with other assays or different people. A recent report from others found that these compounds, plus another 30, were inactive as attractants in three additional parasitic nematode species (Wuyts et al. Nematology 8:89- 101, 2006). Assays designed to test the hypothesis that several compounds together are required to attract nematodes have thus far failed to find a reproducibly active combination. In contrast to results using pure plant compounds, complex unfractionated exudates from aseptic onion root reproducibly attracted D. dipsaci in both the ARO and UCD labs. Onion root exudate collection, separation into HPLC fractions, assays using D. dipsaci and MS-MS experiments proceeded collaboratively between ARO and UCD without any definitive identification of an active compound. The final active fraction contained two major molecules and traces of several other compounds. In the end, analytical studies were limited by the amount of onion root exudate and the complexity of the purification process. These tests showed that aseptic plant roots release attractant molecules, but whether nematodes influence that release, as insects trigger release of attractants from plants, is unknown. Related experiments showed that the saprophyte C. elegans stimulates its prey, Pseudomonas bacteria, to increase production of 2, 4-diacetylphloroglucinol (DAPG) a compound that promotes amino acid exudation by plant roots. It is thus possible that saprophytic nematodes are attracted primarily to their bacterial or fungal prey and secondarily to effects of those microorganisms on root exudation. These observations offer promising avenues for understanding root-zone interactions, but no direct routes to controlling nematodes in agriculture were evident. Extracts from two plant sources, Chrysanthemum coronarium and Sequoia sempervirens, showed nematicidal activity at ARO and UCD, respectively. Attempts to purify an active compound from S. sempervirens failed, but preliminary results from C. coronarium are judged to form a potential basis for further work at ARO. These results highlight the problems of studying complex movement patterns in sentient organisms like nematodes and the issues associated with natural product isolation from complex mixtures. Those two difficulties combined with complications now associated with obtaining US visas, slowed and ultimately limited progress on this project. As a result, US investigators expended only 65% of the $207,400 originally planned for this project. The Israeli side of the project advanced more directly toward its scientific goals and lists its expenditures in the customary financial report.
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Greinert, Jens. Mine Monitoring in the German Baltic Sea 2020; Dumped munition monitoring AL548, 03rd – 16th November 2020, Kiel (Germany) – Kiel (Germany) „MineMoni-II 2020“. GEOMAR Helmholtz Centre for Ocean Research Kiel, 2021. http://dx.doi.org/10.3289/cr_al548.
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ALKOR cruise AL548 took place as part of the EMFF (European Maritime and Fisheries Fund)-funded project BASTA (Boost Applied munition detection through Smart data inTegration and AI workflows; https://www.basta-munition.eu) and as continuation of the munition monitoring started within the BMBF-funded project UDEMM (Environmental Monitoring for the Delaboration of Munition in the Sea; https://udemm.geomar.de/). In October 2018, a first cruise (POS530 MineMoni2018) was conducted, to gather data for a broad baseline study in the German Baltic Sea. Results show a moderate contamination level on regional and coastal scale, but indicate higher levels for specific local areas. Within UDEMM, expertise was developed to detect, exactly locate and monitor munition (e.g. torpedoes, sea mines, ground mines) on the seafloor using optical and hydroacoustic means. In addition, chemical analyses of dissolved contaminants in the water and sediments was performed. Data acquired during this cruise are used in BASTA, which aims for enhanced munition detection via AUV-based artificial intelligence applied on multi-sensor datasets. At the same time, the project ExPloTect (Ex-situ, near-real-time exPlosive compound deTection in seawater) (also EMFF-funded) addresses the need for an innovative approach to detect explosive compounds in seawater. A prototype system was used and successfully tested for the first time during this cruise. The main focus was placed onto the two already known dumpsites Kolberger Heide and Lübeck Bight. Additionally, new areas Falshöft (Schleswig-Holstein) and Cadet Channel, Trollegrund and Großklützhöved (Mecklenburg-Vorpommern) were explored. In each area high-resolution multibeam mapping was performed and contact lists, indicating potential munition objects were produced on board. AUV surveys were conducted to ground-truth possible contacts via detailed photograph and magnetometer mapping. This was complemented with towed video (TV)-CTD profiles. The transits to and between those sites were planned along former constraint routes during WWII. These routes were main targets of the British Air Force and mines and bombs can be expected along these ways. During transits water samples were taken with on a CTD- (conductivity, temperature, depth) rosette-mounted Niskin bottles in regular distances, in order to obtain a comprehensive understanding munition compounds (inter alia trinitrotoluene (TNT)) measurements across the German Baltic Sea.
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Silks, III, Louis A. Catalytic Routes for the Conversion of Biomass Derivatives to Hydrocarbons and/or Platform Chemicals. Office of Scientific and Technical Information (OSTI), październik 2015. http://dx.doi.org/10.2172/1223183.
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Dashtey, Ahmed, Patrick Mormile, Sandra Pedre, Stephany Valdaliso i Walter Tang. Prediction of PFOA and PFOS Toxicity through Log P and Number of Carbon with CompTox and Machine Learning Tools. Florida International University, lipiec 2024. http://dx.doi.org/10.25148/ceefac.2024.00202400.
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Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are two major groups of PFAS will be subjected to the Maximal Contamination Concentration (MCL) of 4 ng/l in drinking water to be implemented by the U.S. EPA by 2025. How to accurately predict toxicity of PFAS with varied carbon chain length is important for treatment and sequential removal from drinking water. This study presents Quantitative Structure and Activity Relationship (QSAR) models developed through both linear regression and two order regression. Log P is compiled from reference and carbon content is counted as the molecule represented. Bioconcentration potential is predicted from CompTox.The results suggest that as log P and carbon content increase, the bioconcentration potential of PFCAs also increases. In other words, larger PFCA molecules tend to be easier to bioaccumulate in living organisms. This finding is crucial because bioconcentration refers to the accumulation of substances from water directly into living organisms through the process of passive diffusion across cell membranes. On the other hand, 96-hour fathead minnow LC50 has an inverse relationship, with higher LC50 values associated with lower log P and fewer carbons. The varying R-squared values across methods indicate differing degrees of correlation, underscoring the impact of compound structure on aquatic toxicity. Similarly, for oral rat LD50 and 48-hour D. magna LC50, the R-squared values reflect moderate to strong correlations with log P and the number of carbons. As the log P and carbon content decrease,the toxicity expressed in LC50 or LD50 increases. This relationship underscores the role of chemical properties in influencing the toxicity of PFCAs across different organisms and exposure routes. For instance, the negative correlation between log P and aquatic toxicity (96-hour fathead minnow LC50 and 48-hour D. magna LC50) suggests that compounds with higher hydrophobicity (higher log P) and more carbons may exhibit lower acute toxicity to aquatic organisms.