SYNTHESIS AND PROPERTIES OF LIPOIC ACID STABILIZED GOLD NANOCLUSTERS

Disulfide lipoic acid was used to synthesize new aqueous soluble gold nanomaterials. The first one is an ultra-small plasmonic nanoparticle displaying a weak plasmonic band at 520 nm. At the transition zone between larger metallic nanoparticles and smaller non-metallic nanoclusters, intriguing electrochemical and optical features were observed. The other cluster is a new molecular-like nanocluster with unique optical features. Distinct UV-visible absorption bands were observed corresponding to discrete energy states/orbitals along with a weak photoluminescence if ultracentrifuge purification is adopted. Dialysis purification yielded a tenfold increase in photoluminescence while the absorption bands diminish. This transition is attributed to the gradual oxidation of some of the sulfur atoms at the core-ligand interface. Annealing with a known amount of excess thiol is shown to expedite and better control the transitions observed through the synthesis and purification along with yielding an enhancement of the electrochemiluminescence by more than ten folds

Studies of the N-end Rule Pathway in Bacteria and Mammals

Many intracellular proteins are either conditionally or constitutively short-lived, with in vivo half-lives that can be as brief as a minute or so. The regulated and processive degradation of intracellular proteins is carried out largely by the ubiquitin (Ub)-proteasome system (UPS), in conjunction with molecular chaperones, autophagy, and lysosomal proteolysis. The N-end rule pathway, the first specific pathway of UPS to be discovered, relates the in vivo half-life of a protein to the identity of its N-terminal residue. Physiological functions of the N-end rule pathway are strikingly broad and continue to be discovered. In bacteria and in eukaryotic organelles mitochondria and chloroplasts all nascent proteins bear the pretranslationally formed N-terminal formyl-methionine (fMet) residue. What is the main biological function of this metabolically costly, transient, and not strictly essential modification of N-terminal Met, and why has Met formylation not been eliminated during bacterial evolution? One possibility is that the formyl groups of N-terminal Met in Nt formylated bacterial proteins may signify a proteolytic role of Nt-formylation. My colleagues and I addressed this hypothesis experimentally, as described in Chapter 3 of this thesis. Among the multitude of biological functions of the mammalian Arg/N-end rule pathway are its roles in the brain, including the regulation of synaptic transmission and the regulation of brain’s G-protein circuits. This regulation is mediated, in part, by the its Ate1-mediated arginylation branch of the Arg/N-end rule pathway. One role of the Ate1 arginyltransferase (R-transferase) is to mediate the conditional degradation of three G-protein down-regulators, Rgs4, Rgs5, and Rgs16. Ate1-/- mice, which lack the Ate1 R-transferase, exhibit a variety of abnormal phenotypes. Chapter 4 describes our studies of neurological abnormalities in Ate1-/- mice (and also in mice that express Ate1 conditionally, upon the addition of doxycycline), with an emphasis on the propensity of these mice to epileptic seizures. </p

Study of Multiphase Networks, Noise Reduction for DC-DC Converters, and Stability Test for Electronic Systems

学位記番号：理工博甲7

FINANCIAL SUSTAINABILITY OF MICROFINANCE INSTITUTIONS IN VIET NAM

Microfinance plays an important role in the nation's financial inclusive system. Therefore, the development of Microfinance Institutions (MFIs) increasingly receives the attention of governments, especially in developing countries. In which, financial sustainability is one of the determinants which measures the development of microfinance institutions (MFIs). In this research, the institutionalist approach is applied with the purpose of developing empirical evidence for the determinants that affect the financial sustainability of MFIs in Viet Nam. Financial sustainability is analyzed through the evaluation criteria of the investors and the wholesale lending organizations. The Fixed Effect Model is applied to determine the factors that affect the financial sustainability of MFIs in Viet Nam. Quantitative results show that the financial sustainability of MFIs is governed by five factors, including (i) the growth rate of MFIs’ outstanding loans, (ii) the efficiency of MFIs’ performance, (iii) the ratio of borrowers to the number of staffs of MFIs with a positive impact; (iv) the debt-to-equity ratio of MFIs; and (v) the incremental cost per client of the MFIs with negative effec

Biomimetic Superhydrophobic Materials for Environmental Applications

Environmental pollution has been one of the people’s most significant concerns for decades. In today’s industrialized and modernized society, the problem of environmental pollution has become more and more serious, directly affecting the sustainable development of each country. The unique surface properties of materials and interfaces produced by biomimetic approaches can be leveraged to create practical solutions to challenging environmental issues. Among them, superhydrophobic materials get a lot of attention because of their exceptional capacities in various environmental applications such as oil-water separation, membrane-based water purification and desalination, biofouling prevention, high-performance vapor condensation, and atmospheric water capture. This chapter reviews and discusses the fundamental principles of superhydrophobicity, recent works in preparing superhydrophobic surfaces, their potential environmental applications, and the challenges confronted in their new applications