Literatura académica sobre el tema "Isotherme Kalorimetrie"

The concept of a self-incompatible solvent is introduced as a molecule composed of two parts (compound 1 and 2) with unfavourable interactions. A third compound will be readily dissolved in this solvent to diminish this unfavourable interaction by dilution. The more incompatible compounds 1 and 2 are, the stronger this behaviour is expected to be. In this work, ionic liquids comprising non-polar carbon chain and polar ionic group are chosen to serve as a model of self-incompatible solvent. The interactions parameters k of the ionic liquids with active ingredients are investigated to examine the effect of self-incompatibility of the ionic liquid molecule. On the other hand, phase separation between compounds 1 and 2 will reduce the positive effect of self-incompatibility. The tendency of phase separation is increasing with increasing size of the two compounds. Thus, if compounds 1 and 2 are blocks tied together into a block copolymer, one expects a decreasing ability of the block copolymer to dissolve an active ingredient with increasing block length. In this work the ability of polybutadiene-block-poly(2-vinylpyridine) (PB-b-P2VP) block copolymers to dissolve the model compound anthracene is investigated. As expected, the solubility indeed decreases with increasing block length.

Self-heating in storage facilities of biomass pellet can lead to spontaneous combustion. This has resulted in many fires over the years, causing both financial and environmental losses. In order to assess the risk for spontaneous combustion of biomass pellets during storage, it is important to know how prone the fuel is to self-heating, i.e. to determine its reactivity. This thesis presents experimental work performed to develop a sensitive screening test procedure for biomass pellets, using isothermal calorimetry for direct measurement of the heat production rate. This method can be used to compare the reactivity of different biomass pellets. This could be useful for e.g. facility owners to gain better knowledge of their fuels propensity for self-heating and thereby facilitate safer storage. The screening test procedure can also be used for research purposes. Experiments have been performed with 31 different biomass pellet batches to investigate how the pellet composition, origin, etc. influence the reactivity of the pellets. The results from these experiments clearly show a significant difference in reactivity between different types of pellets. The results indicate that pine/spruce mix pellets are significantly more reactive than all other types of pellets tested, and that pellets consisting of 100 % pine are more reactive than pellets consisting of 100 % spruce. Pellets produced from winery wastes, straw, or eucalyptus, have low reactivity compared to pellets consisting of pine and/or spruce. The reactivity of the pellets was shown to be reduced by either introducing certain types of anti-oxidants into the pellets or by extracting lipids from the raw material of pellets. The screening test procedure is already being used today by some facility owners for assessing their fuels propensity for self-heating. The procedure is also one of the suggested test methods in “ISO/CD 20049 Solid biofuels — Determination of self-heating of pelletized biofuels”.
This thesis presents experimental work performed to develop a sensitive screening test procedure for biomass pellets, using isothermal calorimetry for direct measurement of the heat production rate. This method can be used to directly compare the reactivity, that is how prone the fuel is to self-heating, of different batches of biomass pellets. The results could be used for safety assessment by the industry or for research purposes to investigate how different factors influence the self-heating potential. Experiments were performed with 31 different biomass pellet batches to investigate how the pellet composition, origin, etc. influence the heat release rate. The results clearly show that there is a significant difference in reactivity between different types of pellets. Pine/spruce mix pellets are more reactive than the other types of pellets tested and pellets consisting of 100 % pine are more reactive than pellets consisting of 100 % spruce. Pellets produced from winery wastes, straw, or eucalyptus, have low reactivity compared to pellets consisting of pine and/or spruce. The results also show that the reactivity of the pellets can be reduced by either introducing certain types of anti-oxidants into the pellets or by extracting lipids from the raw material of pellets.

The study of protein and surfactant interactions is of great significance in a number of applications, such as the cosmetic, food or pharmaceutical industries and many others. However, they require further study due to their compositional complexity and the limitations of current analytical approaches. In this thesis, the cationic surfactant septonex in combination with two differently charged proteins lysozyme and bovine serum albumin under different physiological conditions (temperature, surfactant concentration, environment and others) was selected to study the interactions. Characterization of protein-surfactant interactions is a very important but challenging task, therefore it is essential to use appropriate approaches to explore the nature of these interactions. In order to unify the information to provide rational models, calorimetric methods (DSC, ITC) and dynamic light scattering were used. Isothermal titration calorimetry monitors the evidence for the formation of the system of the mentioned substances and information on aggregation behavior, differential scanning calorimetry characterizes the thermal stability of proteins and dynamic light scattering made it possible to monitor changes in particle size. Both proteins have been proven to interact with positive septonex, even if the lysozyme molecule is also positively charged. However, significant differences were found between the two proteins. From the obtained results it is evident that the identical charge of the protein with the surfactant has an effect on the intensity of the measurement, although all measured interactions showed an endothermic character.

This master thesis deals with the study of thermodynamic and structural aspects of the interactions of humic acids with organic ions. Methylene blue (dye) was used as a model organic ion. The interactions were studied by isothermal titration calorimetry, dissolution calorimetry and by diffusion in diffusion cells.

Vliv hyaluronanu na micelizaci tenzidů byl studován různými fyzikálně-chemickými metodami. Byly zvoleny dva kationaktivní tenzidy, a to tetradecyltrimethylammonium bromid (TTAB) a cetyltrimethylammonium bromid (CTAB). Metoda izotermické titrační kalorimetrie byla využita pro stanovení entalpie micelizace, tenziometrie popisuje povrchové vlastnosti daných vzorků. Byl sledován také vliv různé molekulové hmotnosti použitého hyaluronanu a délka alkylového řetězce tenzidu na agregační chování daného systému. Výsledkem jsou hodnoty kritické micelární nebo agregační koncentrace tenzidu. V neposlední řadě se diskutuje využití agregátů hyaluronan-tenzid jako možné nosiče pro cílenou distribuci léčiv.

The presented diploma thesis deals with the study of interactions between humic acids as the main component of soil organic matter with a model organic pollutant presented by cationic surfactant Septonex (which was expected to interact positively with humic acids due to its charge) through unconventional combination of dialysis and diffusion techniques realized in diffusion cells together with isothermal titration calorimetry capable of elucidating the nature of ongoing reactions from a thermodynamic point of view. The experiments were performed with a humic acid isolated by standard isolation procedure from Leonardite (1S104H) purchased from the International Society for Humic Substances, with humic acids isolated from lignite as well as modal chernozem. The aim of the submited diploma thesis is to assess the influence of carboxyl functional groups in the structure of humic acids to interactions with Septonex. For this reason, said samples of humic acids have been modified by selective methylation of their carboxyl functional groups, which can no longer participate in interactions with ionic substances. Results from diffusion cells and isothermal titration calorimetry confirmed the assumption that Septonex interacted with all types of unmodified humic acids more than with their methylated derivatives. Despite the available literature, it was surprising that the differences in the interaction of humic acids with Septonex were not diametrically different when comparing unmodified humic acids with their methylated derivatives. The extent of these interactions was assessed through the apparent equilibrium constant Kapp determined in the diffusion (dialysis) experiments and from the course of enthalpy curves from isothermal titration calorimetry. After the experiments and their evaluation, it can be concluded that humic acids and Septonex in their interactions, due to their structures, probably apply not only electrostatic interactions, especially through available carboxyl functional groups of humic acids and positively charged hydrophilic parts of Septonex molecules, but also a significant role have a hydrophobic effect, hydrogen bonds and Van der Waals forces.

The main object of the diploma thesis is study of interaction beetween humic acids and selected metal ions using calorimetric titration. The research about reactivity of humic substances is done comparing the different models used to describe the variety of properties of humic substances. In experimental part the methods of FT-IR spektrometry, potenciometric and conductometric titration are used to recieve the total acidity and carboxylic acidity of lignite humic acid. The optimalization of isothermic titration calorimetry is done to be used within study of reactivity of humic acids, revealing the best correlation with sols of studied humic acid. The basic organic compounds were used including benzoic acid, ftalic acid, salycilic acid, pyrocatechol and phenol as models of bonding groups in humic acids. The reaction enthalpy was calculated from the titration of models and results were compared with semiempiric quantum chemistry calculations following INDO method.

This diploma thesis deals with study of crystalline structure of polyhydroxybutyrate (PHB), which contains different types of additives for studying of their nucleation activity and which were prepared by mixing. It is about boronitrid (BN), sacharin, hydroxapatit, plasticizer Tegmer a tree types of talc. Crystal structure was analysed by differential scanning calorimetry and x-ray diffraction, supramolecular structure was observed by optical microscopy (polarized and confocal laser scanning). Nucleating activity was evaluated by isothermal and non-isothermal crystallization made on calorimeter and heated table of optical microscope. There is not influence of additives on crystallographic structure, but additives affects number and size of spherulites including crystal domains defects, which can have impact on final mechanical properties. BN and talcs react as nucleating agents, other additives during low and high cooling speeds (vc) inhibit nucleation and in middle cooling speeds are without effect. Nucleating activity is not evaluated by numerically, because decrease of crystallization temperature together with vc is not linear. Results of direct methods are based on picture analysis, which is great benefit for understanding of crystal behaviour of PHB.

At present, soils face great threats. Consequences of human activities, such as climate change, acidification and contamination result in decreased soil health. This is a threat to human health and well-being, since our society is dependent on soil ecosystem services. The soil ecosystems provide resources, such as food and fresh water, regulate the climate and play key parts in important life supporting biological processes, e.g. cycling of carbon and nutrients. Due to increased awareness of the threats that soils face, and its importance to humans, soil quality monitoring has recently received increased attention. Microorganisms run most biological processes in the soil, such as decomposition of organic material and nutrient cycling. Thus, microbial activity and diversity are considered useful biological indicators for soil quality monitoring. These biological properties can be examined using different methods. The aim of the project was to evaluate the potential of multiple substrate-induced respiration (MSIR), using the MicroRespTM system, and isothermal calorimetry for determining microbial activity and diversity in soils contaminated with copper (Cu) and polycyclic aromatic hydrocarbons (PAH). Thereby, the methods’ applicability in risk assessment of contaminated soil could be decided. MSIR is considered appropriate for determining microbial activity and functional diversity, while isothermal calorimetry has not been tested as much in this area. The calorespirometric ratio (produced heat per unit CO2) was calculated to evaluate potential relationships between heat and CO2 at different contamination levels. Although there was some variation between the methods, Cu had a clear effect on both microbial activity and functional diversity. Both methods were thus considered applicable in risk assessment of soil contaminated with Cu. The impact of PAH appeared to be more complex, the effects on microbial activity varied and PAH had little significant effect on functional diversity. Neither of the methods were therefore considered applicable for assessment of soil contaminated with PAH. The calorespirometric ratio did not provide useful results, and cannot be recommended for risk assessment purposes at present.
I dagsläget utsätts marken för stora hot. Följder av mänsklig aktivitet, så som klimatförändringar, försurning och förorening försämrar markens kvalitet. Detta är ett hot mot människors hälsa och välmående, eftersom vårt samhälle är beroende av markens ekosystemtjänster. Markens ekosystem förser oss med exempelvis mat och rent vatten, reglerar klimatet, och har nyckelroller i viktiga biologiska processer, exempelvis cirkulering av kol och näringsämnen. På grund av ökad medvetenhet om hoten mot marken samt dess betydelse för människan, har kontroll av markens kvalitet börjat få ökad uppmärksamhet. Mikroorganismer sköter de flesta biologiska processer som sker i marken, så som nedbrytning av organiskt material och cirkulering av näringsämnen. Därmed anses mikrobiell aktivitet och diversitet vara lämpliga biologiska indikatorer vid kontroll av markens kvalitet. Dessa biologiska egenskaper kan mätas med flera olika metoder. Syftet med projektet var att utvärdera potentialen i att använda multipla substrat-inducerad respiration (MSIR), genom att använda systemet MicroRespTM, samt isotermisk kalorimetri för att mäta mikrobiell aktivitet och funktionell diversitet i mark förorenad med koppar (Cu) och polycykliska aromatiska kolväten (PAH). Därmed kunde metodernas tillämplighet i riskbedömning av förorenad mark bestämmas. MSIR anses vara en lämplig metod i syfte att undersöka mikrobiell aktivitet och funktionell diversitet, medan isotermisk kalorimetri inte är lika beprövat. Kvoten mellan värmeproduktion och respirerad CO2, the calorespirometric ratio, beräknades för att utvärdera eventuella samband mellan värmeproduktion och respiration vid olika föroreningskoncentrationer. Trots att det förekom viss variation mellan metoderna, hade Cu en tydlig effekt på både mikrobiell aktivitet och funktionell diversitet. Båda metoder ansågs därför vara tillämpbara i riskbedömning av Cu-förorenad jord. PAH hade varierande effekt på mikrobiell aktivitet och liten signifikant effekt på funktionell diversitet. Ingen av metoderna ansågs därför tillämpbar i riskbedömning av jord förorenad med PAH. The calorespirometric ratio tillhandahöll ej användbara resultat, och kunde därmed inte rekommenderas i riskbedömningssyfte.

This thesis is focused at possibilities of preparation and characterization of XRD-amorphous delaminated and dehydroxylated talc phase – meta-talc, which can have its potential application and a starter material for a preparation of magnesium-silicate analogues of geopolymers. Changes in structure and morphology of talc ore were observed during this work. For the purposes of this research, two various talc ores – chloritic and dolomitic were examined. Whole process of meta-talc preparation was examined with whole scale of instrumental techniques such as X-ray diffraction, simultaneous thermogravimetric a differential thermal analysis, infrared spectroscopy, scanning electron microscopy or laser analysis of particle size. Meta-talc can be obtained via mechanochemical activation of talc ore with subsequent calcination. Mechanochemical treatment lead to destruction of original crystal structure and breaking of original bonds, i.e. the product of this treatment was almost amorphous and delaminated. Most of hydroxyl groups were converted to molecules of water which remained adsorbed or coordinated in ore structure. These molecules were removed during calcination step.