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Full-Text Articles in Physical Sciences and Mathematics
Hybrid Catalysis For The Direct Addition Of Unactivated Aldehydes And Ketones To Alkenes And Alkynes, Jacob Porter
Hybrid Catalysis For The Direct Addition Of Unactivated Aldehydes And Ketones To Alkenes And Alkynes, Jacob Porter
Dissertations (1934 -)
Reactions for the alpha functionalization of carbonyl compounds are important for the synthesis of complex organic materials such as pharmaceuticals, agrochemicals, and natural products. Current methodology used to perform these reactions is inefficient in that pre-activated coupling partners or sensitive catalysts are usually required. Described herein is the study and development of bifunctional and dual catalytic systems for carbon-carbon bond formation via the direct addition of unactivated carbonyl compounds to unactivated alkenes/alkynes. A dual catalyst system is one which utilizes two distinct catalysts to simultaneously activate separate reactants, and in a bifunctional catalyst the two catalytic components are present separately …
The Alpha-Activator Complex, Cellular Maturation, And Catalytic Mechanism Of Iron-Type Nitrile Hydratase, Wasantha Lankathilaka Karunagala Pathiranage
The Alpha-Activator Complex, Cellular Maturation, And Catalytic Mechanism Of Iron-Type Nitrile Hydratase, Wasantha Lankathilaka Karunagala Pathiranage
Dissertations (1934 -)
In industry, chemicals are typically synthesized through catalytically accelerated chemical processes. The use of biocatalysts is an increasingly important trend in achieving environmentally friendly chemical production processes. Nitrile Hydratases (NHases) are well-known biocatalysts that are used by several manufacturers such as Mitsubishi Rayon Corporation and Lonza for the conversion of acrylonitrile to acrylamide and 3-cyanopyridine to nicotinamide, respectively. Amides, in general, are used in polymer preparation, adhesive manufacturing, and the paper industry. Refrigeration is needed in the enzymatic hydration process on the industrial scale to maintain a low reaction temperature to stabilize the NHase enzyme. The use of whole cells …
Structure And Mechanisms Of Metalloenzymes For Incorporation Of Water Across Cn And C-Cl Bonds, Xinhang Yang
Structure And Mechanisms Of Metalloenzymes For Incorporation Of Water Across Cn And C-Cl Bonds, Xinhang Yang
Dissertations (1934 -)
Metalloenzymes are widely involved in water incorporation across CN and C-Cl bonds.1 In this research, the structure and mechanisms of two novel metalloenzymes that incorporate water across CN and C-Cl bonds were examined by biophysical approaches, computational modeling, and crystallographic methods.In the research of water incorporation across CN bonds, a novel eukaryotic nitrile hydratase (NHase, EC 4.2.1.84) from Monosiga brevicollis (MbNHase) was characterized, and the functional role of a (His)17 section and an insert region in the MbNHase, were examined by gene modifications. Each of these MbNHase enzymes provided an 22 heterotetramer, identical to that observed for prokaryotic NHases …
Investigation Of The Active Site Maturation And Catalytic Mechanism Of Nitrile Hydratases (Nhase, E.C.4.2.1.84), Irene Anyango Ogutu
Investigation Of The Active Site Maturation And Catalytic Mechanism Of Nitrile Hydratases (Nhase, E.C.4.2.1.84), Irene Anyango Ogutu
Dissertations (1934 -)
Nitrile hydratase (NHase, E.C.4.2.1.84) is a metalloenzyme that catalyzes the hydration of nitriles into their corresponding amide under ambient conditions. NHase enzymes contain either a non-heme Fe3+ ion or a non-corrin Co3+ ion in their active site. NHase enzymes have industrial applications as biocatalysts in the large-scale production of acrylamide and nicotinamide, though it’s catalytic and biochemical properties are not fully understood. This research project provides insight into the active site maturation process and catalytic mechanism of NHase using peptide model complexes, site-directed mutagenesis and synthesis of deuterated proteins.Insight into the sequential maturation of the NHase active site has been …
Design And Synthesis Of Simplified Analogs Of The Natural Product Sordarin As Potential Antifungal Agents, Yibiao Wu
Dissertations (1934 -)
Invasive fungal infection is a life-threatening illness that causes high mortality, and is especially common among patients with compromised immune systems. However, currently there are only three major classes of clinically useful drugs capable of treating such infections. In addition, due to the fact that drug resistance has become a serious issue especially among patients who suffer from chronic infections, it is urgent to identify new drug candidates, particular those of new classes. The discovery of the natural product sordarin and its novel mechanism of action of inhibiting fungal protein synthesis via the fungal eukaryotic elongation factor 2 (eEF2) led …
Bifurcation In Weighted Digraphs And Their Applications In Ecology, Kehinde Irabor
Bifurcation In Weighted Digraphs And Their Applications In Ecology, Kehinde Irabor
Dissertations (1934 -)
Merrill (2010) described bifurcation in a Markov chain by examining the eigenvalues of the associated probability matrix. The bifurcation point is that point where the dynamics of the system’s structure changes. He recognized a change in the dynamics of a sample path in a Markov chain when the nature of its eigenvalues changes. We built upon this work and found that not all changes in Markov chain dynamics are accompanied by change in the nature of the eigenvalues. And we introduce other measures that will recognize a change in dynamics. This was applied to solve the problem of evaluating the …
Evaluating Electrode-Tissue Contact Force Using The Moving Pattern Of The Catheter Tip And The Electrogram Characteristics, Xuyong Yu
Dissertations (1934 -)
As an important reference for the physician during catheter ablation, the electrode-tissue contact force (CF), is one of the key points for the success of the catheter ablation. With the guide of CF sensing, the ablation procedure can be safer and more effective. Techniques and apparatus have been refined since catheter ablation was invented to treat cardiac arrhythmia. In the review part, different techniques for evaluating the electrode-tissue CF are discussed, including both direct and indirect measurement. Sensor-based direct measurement is broadly applied but restricted by the high cost. Surrogate markers of catheter-tissue contact such as impedance, electrogram (EGM) quality, …
Best (Biomarker Estimation): Health Biomarker Estimation Non-Invasively And Ubiquitously, Md Kamrul Hasan
Best (Biomarker Estimation): Health Biomarker Estimation Non-Invasively And Ubiquitously, Md Kamrul Hasan
Dissertations (1934 -)
This dissertation focuses on the non-invasive assessment of blood-hemoglobin levels. The primary goal of this research is to investigate a reliable, affordable, and user-friendly point-of-care solution for hemoglobin-level determination using fingertip videos captured by a smartphone. I evaluated videos obtained from five patient groups, three from the United States and two from Bangladesh, under two sets of lighting conditions. In the last group, based on human tissue optical transmission modeling data, I used near-infrared light-emitting diode sources of three wavelengths. I developed novel image processing techniques for fingertip video analysis to estimate hemoglobin levels. I studied video images creating image …