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Full-Text Articles in Physical Sciences and Mathematics

Electron Transport And Sensor Characteristics Of Tin Dioxide Based Nanocrystalline Materials, Allen Chaparadza May 2009

Electron Transport And Sensor Characteristics Of Tin Dioxide Based Nanocrystalline Materials, Allen Chaparadza

Dissertations and Theses

Wide band gap, transparent semiconductor Sn02 is an n-type conductor and is widely used as a sensor material as well as transparent electrode material e.g. in solar cells and flat panel displays. Recent discovery of p-type doping with Li has opened exciting possibilities in new classes of sensors and transparent nanoelectronic devices. Li-doping in SnO2 nanoparticles was explored through a gel-sol method of synthesis to examine the influence of reaction conditions such as pH, dopant concentration, and calcination temperature. The Li doping in nanoparticles was characterized using nuclear reaction analysis and the nanostructure with high-resolution electron transmission microscopy …


Characterization Of Putative Self-Resistance Genes In The Biosynthetic Gene Cluster Of Hygromycin A From Streptomyces Hygroscopicus Nrrl 2388, Vidya Dhote Feb 2009

Characterization Of Putative Self-Resistance Genes In The Biosynthetic Gene Cluster Of Hygromycin A From Streptomyces Hygroscopicus Nrrl 2388, Vidya Dhote

Dissertations and Theses

Streptomyces hygroscopicus NRRL 2388 produces an aminocyclitol antibiotic called hygromycin A (HA), which targets bacterial protein synthesis by inhibiting the peptidyl transferase reaction. The hyg6, hygl9, hyg21, hyg28, and hyg29 genes in the biosynthetic gene cluster of HA are predicted to confer self-resistance to the producer strain by different mechanisms. Targeted gene disruptions and in vitro characterization of recombinant proteins were carried out to elucidate the functions of these genes. The hyg21 gene encodes an O-phosphotransferase with a proposed role in HA inactivation by phosphorylation. Disruption of hyg21 led to a significant decrease in HA production but did not …


Synthesis Of Aptamer-Porphyrin Conjugate For Photodynamic Therapy & Synthesis And Stability Of Mixed Thiol/Lipid Coated Gold Nanoparticles, Sarita Sitaula Feb 2009

Synthesis Of Aptamer-Porphyrin Conjugate For Photodynamic Therapy & Synthesis And Stability Of Mixed Thiol/Lipid Coated Gold Nanoparticles, Sarita Sitaula

Dissertations and Theses

An underlying problem in Photodynamic Therapy (PDT) is low selectivity of photosensitizers currently being used for the treatment of tumors. This thesis is focused on developing new PDT drugs and is divided into two parts. The first chapter describes a method for selective delivery of the photosensitizers to the tumor site by conjugating porphyrins to an aptamer for the targeted PDT. To achieve this, a novel synthesis of 2'-porphyrin-modified uridine was developed. The 3'-H-phosphonate derivatives of both 2'-porphyrin and 2'-dithiaporphyrin modified uridine were also synthesized. The 3'41-phosphonate derivative of 2'-porphyrin-modified uridine was conjugated to a 19-mer DNA and to a …