No description available.

No description available.

No description available.

The process of transesterification is the exchange of the organic group R” of an ester with the organic group R’of an alcohol, often catalyzed by acid, base or enzyme. Biodiesel, a mixture of monoalkyl esters of long chain fatty acids, is produced from vegetable oils, animal fats and fish oils by transesterification in presence of alcohol. Biodiesel is a fuel which can be used in a mixture of other fuels or alone. The base catalyzed transesterification method of biodiesel production is not suitable for waste animal fat as it contains 10–15% free fatty acids which result in higher soap formation and cause extensive downstream processing. Enzyme catalyzed transesterification can overcome the problem of soap formation and multi-step purification of end products and results in a higher purity biodiesel. Lipase is the enzyme widely used in the process of enzymatic transesterification. Various lipases have been used to transesterify triglycerides with short chain alcohols to alkyl esters. The objectives of this study were to screen lipase enzymes for the transesterification process and to use the best lipase for biodiesel production from waste animal fat. Enzymatic transesterification by individual and combined enzyme catalysts (Novozyme 435 and NS88001) was first carried out to investigate the effects of reaction time (4, 8, 12 and 16 hour), oil : alcohol molar ratios (1:1, 1:2, 1:3, 1:4 and 1:5), the effects of alcohol type (methanol and 2-butanol) and reaction temperature (35, 40, 45 and 50°C) on biodiesel yield in solvent and solvent-free systems. The highest conversion yield of biodiesel (96.67%) was obtained from a combination of Novozyme and NS88001 lipase with the optimal reaction condition of oil : 2-butanol molar ratio of 1:4, enzyme concentration of 25% (12.5% w/w of each enzyme), hexane as solvent, a 45°C reaction temperature, a reaction time of 16 h and a mixing speed of 200 rpm. The reusability of lipase enzymes by individual and combination of enzyme catalysts (Novozyme 435 and NS88001) with solvent and solvent-free systems was also investigated in order to reduce the cost of the process. The lipase enzymes lost their activity after being reused for 30 cycles in solvent-free systems and after 10 cycles in solvent system.

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 145-154).

M.Sc. (Biochemistry) / Please refer to full text to view abstract

Indiana University-Purdue University Indianapolis (IUPUI) / The export of phosphorus (P) from agricultural watersheds has been extensively investigated but monitoring efforts have generally focused on inorganic P (Pi or soluble reactive phosphorus [SRP]), the P fraction thought to be immediately available to algae. However, in settings where no-till management is implemented and organic matter accumulates on soil surface, the amount of organic P (Po) in agricultural drainage waters can be significant and may represent another important P source to fuel algal growth in receiving water bodies. From a 2018 monitoring study at a Central Indiana agricultural watershed, measured total P and SRP loss amounted to 1.22 and 0.17 kg P/ha/year, respectively, indicating that the bulk (84%) of P exported from that watershed was in organic form. Results also showed that tile drainage was the main pathway for P transport (96% of Po loss). In light of these observations, the bioavailability of Po in agricultural drainage waters was investigated in 2019, and the effect of hydrologic flow path (surface versus subsurface flow) on the biochemical attributes of Po was examined. In these assessments, the iron strip method and a suite of enzymatic assays were used to gain a better understanding of the chemical composition of the exported Po. Higher concentration of labile Po was consistently measured in tile discharge than in surface runoff (59% versus 38% of the total bioavailable P). Further, the concentration of EHP (enzymatically hydrolysable P), in the form of monoester, diester, and phytate compounds, was highest during the summer season, for both tile and surface pathways. This elevated bioavailability of Po during the summer is a concern because, in combination with favorable water temperature and solar radiation during that period, this could lead to enhanced Po mineralization and release of Pi, resulting in further algal proliferation and continued degradation of water quality. Considering the high prevalence of tile drainage in agricultural landscapes of the US Midwest, this finding underscores the need for further investigation of the impact of land management and climate on the speciation and bioavailability of Po in the region’s agricultural waters.

To combat diabetes mellitus(DM), a chronicle metabolic disease, from which more than 400 million people suffered in the world, the patients must check the blood glucose level 4-5 times daily with an enzyme-based blood glucose meter and adjust blood glucose levels accordingly. The problem is that enzymatic glucose meters become unstable in the tropics. Therefore, the non-enzymatic method has been urged for blood glucose monitoring, among which the transition metal oxide electrode was found to be promising. However, despite the prolonged effort, its linear detection range is usually much smaller than the glucose level of diabetic patients, calling for an effective solution. Despite many previous attempts, none have solved the problem. Such a challenge has now been conquered by raising the NaOH concentration in the electrolyte, where amperometry, X-ray diffraction, Fourier-transform infrared spectroscopy, and Nuclear magnetic resonance measurements have been conducted. The linear range has been successfully enhanced to 40 mM in 1000 mM NaOH solution, and it was also found that NaOH affected the degree of glucose oxidation, which influenced the current response during sensing. It was expected that the alkaline concentration must be 25 times higher than the glucose concentration to enhance the linear range, much contrary to prior understanding. / Thesis / Candidate in Philosophy

Le domaine de la bioélectronique, qui couple l'électronique et la biologie, présente un fort potentiel pour le développement de nouveaux outils biomédicaux. Les dispositifs à base d’électronique organique sont particulièrement prometteurs; l'utilisation de ces matériaux organiques confère une interface idéale entre les mondes biologique et électronique en raison de leur biocompatibilité et de leur possible grande flexibilité. Le transistor électrochimique organique (OECT) représente un dispositif prometteur dans ce domaine. Des OECT ont par exemple été intégrés dans des systèmes permettant de détecter localement l’activité ionique/biomoléculaire, de mesurer l'activité d'une cellule unique, mais aussi d’effectuer la caractérisation de tissus et le suivi du fonctionnement d’organes entiers. L'OECT est un dispositif extrêmement polyvalent qui apparaît comme un outil thérapeutique et de diagnostic de première importance. L'utilisation de matériaux organiques tels que les polymères conducteurs, rend l‘OECT adaptable pour une large gamme d'applications. Un exemple représentatif est le capteur de glucose. L'OECT, en raison de ses propriétés d'amplification, peut augmenter ces courants de plusieurs ordres de grandeurs. Utilisé comme capteur de glucose, il montre une forte sensibilité et des limites de détection des concentrations de l’ordre du nanomolar. Cependant, en dehors d’une meilleure précision de mesure, la stabilité est nécessaire pour les applications à long terme. Par exemple, ces capteurs se doivent d'enregistrer en continu les variations de glycémie chez des personnes pendant plusieurs jours et sans défaillance. Le glucose est la source d'énergie principale du cerveau. Ainsi, l'enregistrement de la modulation des niveaux de glucose avant et/ou pendant la crise d'épilepsie peut donner beaucoup d'informations dans la compréhension de cette maladie. Pour des applications à long termes, une liaison covalente de la biomolécule est préférable.La biofonctionnalisation des polymères conducteurs, qui sont utilisés comme matières actives dans les OECTs, est une étape obligatoire qui mettra en évidence les propriétés de l’OECT telles que la biocompatibilité, la stabilité, et la fonctionnalité. Dans ce travail, des méthodes de biofonctionnalisation du poly (3,4-éthylènedioxythiophène) dopé avec des anions de tosylate (PEDOT: TOS) ou dopé avec du poly (styrène sulfonate) (PEDOT: PSS) ont été développéeset ont conduitsent à des améliorations telles que la biocompatibilité accrue avec les cellules et à une stabilité accrue pour les applications de détection. En outre, nous avons étudié l'utilisation de liquides ioniques en combinaison avec des polymères réticulables comme alternatives aux électrolytes conventionnelles. Ces gels ioniques électrolytes ont amélioré la stabilité des enregistrements électrophysiologiques. Enfin, des mesures in vitro de l'activité métabolique de la cellule ont été effectuées. Le suivi de l'absorption du glucose et de la conversion en lactate fournit des informations sur la santé des cellules et comment ses activités métaboliques sont affectées par la présence de composés toxiques et d’agents pathogènes. / The rising field of bioelectronics, which couples the realms of electronics and biology, holds huge potential for the development of novel biomedical devices for therapeutics and diagnostics. Organic electronic devices are particularly promising; the use of robust organic electronic materials provides an ideal bio-interface due to their reported biocompatibility, and mechanical matching between the sensor element and the biological environment, are amongst the advantages unique to this class of materials. One promising device emerging from this field is the organic electrochemical transistor (OECT). The OECT combines properties and characteristics that can be tuned for a wide spectrum of biological applications. These applications have allowed the development of OECTs to sense local ionic/biomolecular and single cell activity, as well as characterization of tissue and even monitoring of function of whole organs. The OECT is an extremely versatile device that emerges as an important player for therapeutics and diagnostics.The use of organic materials, such as conducting polymers, makes the OECT tunable for a wide range of applications. For example, OECTs have been used for sensing applications. A representative example is the glucose sensor. The OECT has been used as glucose sensor and has shown high sensitivities and low limit of detection for concentrations at the nanomolar range. However, apart from high sensitivities, stability and reproducibility are common necessities for long term applications. For example, it is of equal importance for these sensors to continuously record variations of glucose for diabetic patients, since multiple measurements per day without failure are necessary. Additionally, stability is necessary for implantable sensors. For brain cells such as neurons, glucose is the main energy source. Thus recording modulations of glucose levels before or during an epileptic crisis will enhance our understanding of this disease. Long-term stabilities for these sensors can be achieved through biofunctionalization, which is a method to attach a biomolecule to a device. For long term applications a covalent binding of the biomolecule is preferred. Biofunctionalization of conducting polymers, which are used as active materials in OECTs, is a mandatory step that can enhance OECT properties such as biocompatibility, stability, and functionality. In this work, different biofunctionalization methods of poly(3,4-ethylenedioxythiophene) doped with tosylate anions (PEDOT:TOS) or doped with poly(styrene sulfonate) (PEDOT:PSS) have been explored. The biofunctionalization methods have led to improvements for different applications such as better interfaces with living cells, and better stability for enzymatic sensors. Additionally, we have employed the use of ionic liquids in combination with cross-linkable polymers as alternative solid state electrolytes. These electrolytes are improving the stability of recordings in electrophysiology. Finally, in vitro measurements of metabolic activities in cells have been explored. The monitoring of glucose uptake and its conversion to lactate is a sensitive indicator of the viability of these cells. Furthermore, in the presence of toxic compounds and pathogens, the nature or kinetics of these metabolic activities is getting affected. Therefore, OECTs used for glucose and lactate sensing can at the same time be used for Immunosensing.