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Full-Text Articles in Physical Sciences and Mathematics

Spectral Reflectance As An Indicator Of Foliar Concentrations Of Arsenic In Common Sunflower (Helianthus Annuus), Yuridia Patricia Peralta De Gandy Dec 2010

Spectral Reflectance As An Indicator Of Foliar Concentrations Of Arsenic In Common Sunflower (Helianthus Annuus), Yuridia Patricia Peralta De Gandy

Theses and Dissertations - UTB/UTPA

Studies were conducted to investigate the use of spectral reflectance by foliage of common sunflower as a potential indicator of arsenic contamination of soil. Germination method was developed for sunflower seeds, and cohorts of sunflower seedlings in hydroponic tanks were established. The cohorts were exposed to 0 ppm, 5 ppm, 7.5 ppm, and 10 ppm treatments of As (V) and reflectance measurements of foliage were collected using a spectroradiometer during two experiments.Results demonstrated the feasibility of using spectral reflectance by foliage of common sunflower as a potential indicator of arsenic contamination. In both experiments, arsenic concentrations in leaf tissues were …


A Highly Efficient Bismuth Salts-Catalyzed Route For The Synthesis Of Alpha-Aminophosphonates, Antara Banik, Sahil Batta, Debasish Bandyopadhyay, Bimal K. Banik Nov 2010

A Highly Efficient Bismuth Salts-Catalyzed Route For The Synthesis Of Alpha-Aminophosphonates, Antara Banik, Sahil Batta, Debasish Bandyopadhyay, Bimal K. Banik

Chemistry Faculty Publications and Presentations

A convenient synthesis of different types of α-amino phosphonates via one-pot solvent-free three component reactions of aldehydes, amines and phosphites catalyzed by bismuth salts has been investigated. Bismuth triflate is found to be the most effective catalyst for this reaction.


Importance Of Electronic Relaxation For Inter-Coulombic Decay In Aqueous Systems, Craig P. Schwartz, Shervin Fatehi, Richard J. Saykally, David Prendergast Nov 2010

Importance Of Electronic Relaxation For Inter-Coulombic Decay In Aqueous Systems, Craig P. Schwartz, Shervin Fatehi, Richard J. Saykally, David Prendergast

Chemistry Faculty Publications and Presentations

Inspired by recent photoelectron spectroscopy experiments on hydroxide solutions, we have examined the conditions necessary for enhanced (and, in the case of solutions, detectable) inter-Coulombic decay (ICD)—Auger emission from an atomic site other than that originally excited. We present general guidelines, based on energetic and spatial overlap of molecular orbitals, for this enhancement of inter-Coulombic decay-based energy transfer in solutions. These guidelines indicate that this decay process should be exhibited by broad classes of biomolecules and suggest a design criterion for targeted radiooncology protocols. Our findings show that photoelectron spectroscopy cannot resolve the current hydroxide coordination controversy.


Study On Energy Absorption Behaviors Of Hydrophobic Mesoporous Materials, Zhongyuan Sun Aug 2010

Study On Energy Absorption Behaviors Of Hydrophobic Mesoporous Materials, Zhongyuan Sun

Theses and Dissertations - UTB/UTPA

Nanoporous energy absorption system has been developed tremendously as an advanced energy storage system in recent years. This research is to optimize the mesoporous energy absorption matrixes via surface treatment to find out the optimum conditions for higher energy conversion efficiency. Five mesoporous silica matrixes with pore size in a range of 3 to 31.6 nm were investigated. Six alkylchlorosilanes were used as the modification reagents. The results showed that the energy absorption density via pressure-induced infiltration is as high as 8.0 J/g which is 100 times larger than that of conventional energy absorption materials. The controllability of the energy …


An Effective Microwave-Induced Iodine-Catalyzed Method For The Synthesis Of Quinoxalines Via Condensation Of 12-Diamines With 12-Dicarbonyl Compounds, Debasish Bandyopadhyay, Sanghamitra Mukherjee, Robert R. Rodriguez, Bimal K. Banik Jun 2010

An Effective Microwave-Induced Iodine-Catalyzed Method For The Synthesis Of Quinoxalines Via Condensation Of 12-Diamines With 12-Dicarbonyl Compounds, Debasish Bandyopadhyay, Sanghamitra Mukherjee, Robert R. Rodriguez, Bimal K. Banik

Chemistry Faculty Publications and Presentations

A microwave-induced iodine-catalyzed simple, rapid and convenient synthesis of different types of quinoxalines via condensation of 1,2-diamines with 1,2-dicarbonyl compounds has been accomplished with an excellent yield.


An Exploratory Study Of Methicillin-Resistant Staphylococcus Aureus And Sccmec Elements Obtained From A Community Setting Along The Texas Border With Mexico, David R. Ammons, Raghuveer Puttagunta, Jose C. Granados, Georgina De La Garza, George Eyambe, Joanne Rampersad-Ammons May 2010

An Exploratory Study Of Methicillin-Resistant Staphylococcus Aureus And Sccmec Elements Obtained From A Community Setting Along The Texas Border With Mexico, David R. Ammons, Raghuveer Puttagunta, Jose C. Granados, Georgina De La Garza, George Eyambe, Joanne Rampersad-Ammons

Chemistry Faculty Publications and Presentations

An exploratory study of methicillin-resistant Staphylococcus aureus (MRSA) and SCCmec elements in bacteria along the Mexican border of south Texas was performed. Between September and December of 2008, 375 swabs of anterior nares were self-collected by students attending the University of Texas-Pan American (UTPA) and cultured for MRSA. Fifty seven bacterial isolates were kept for further analysis that included suspected MRSA and other SCCmec-containing bacteria. Isolates were examined for the presence of nuc, mecA, lukS-PV, and spa genes using PCR. SCCmec and spa typing were also performed. Seven S. aureus isolates were found …


A Proposal For The Mechanism Of The Iron-Ascorbate, Fenton, And Hydroxyl Radical-Quenching Series, Jonathan Velasco May 2010

A Proposal For The Mechanism Of The Iron-Ascorbate, Fenton, And Hydroxyl Radical-Quenching Series, Jonathan Velasco

Theses and Dissertations - UTB/UTPA

The Fenton reaction between [Fe(II)] and [HOOH] is observed in the presence of ascorbic acid, [AscH-], during [Fe(III)] and HO• reduction; this is done as part of consecutive redox reactions between [Fe(III)] and [Fe(II)]. As a result, the rate orders with respect to [Fe(III)], ascorbic acid, and [HOOH] are of (approximately) 2nd, 1st, and 4 th order, respectively. However, the rate constants for each reaction in this study show patterns when measured against solution pH; empirically, reactions proceed faster at smaller pH and vice versa.


Identification Of Phosphatases Involved In E2f-Associated Apoptosis, Liza D. Morales Smith May 2010

Identification Of Phosphatases Involved In E2f-Associated Apoptosis, Liza D. Morales Smith

Theses and Dissertations - UTB/UTPA

Retinoblastoma (Rb) is a tumor suppressor protein that controls a critical checkpoint between the G1 phase and the S phase of the cell cycle. Rb is able to suppress cell proliferation by binding to the E2F family of transcription factors, inhibiting its ability to activate transcription of genes necessary for cell cycle progression. Mutations in proteins involved with the Rb/E2F pathway can result in hyper-proliferative cells that overtime can acquire and accumulate additional mutations, which could lead to tumorigenesis. To prevent hyper-proliferation, aberrant cells can be eliminated through apoptosis. E2F can induce apoptosis through two pathways: through transactivation of the …


A Synthetic Approach Toward Novel Β-Lactams, Mohamed Hashim May 2010

A Synthetic Approach Toward Novel Β-Lactams, Mohamed Hashim

Theses and Dissertations - UTB/UTPA

β-lactam antibiotics which is a class by itself, covers a wide range of antibiotics that includes penicillin, penicillin derivatives, cephalosporins, carbapenems, and any antibiotic agent that contains a 2-azetidinone ring.[2] In recent past research it has been established that β-lactams show therapeutic and anticancer activity with low toxicity. [2] It has also been reported by our lab that N-chrysenyl and N-phenanthrenyl 3-acetoxy-4-aryl-2- azetidinone can exhibit potent selective anticancer activity towards prostate, colon, pancreatic cancer and leukemia at low concentrations, all of this was revealed by means of a structure activity study. [2] The goal of our research is the synthesis …


Genotyping Of Tgif Polymorphisms Associated With Schizophrenia And Psychosis, George Vera Jr. May 2010

Genotyping Of Tgif Polymorphisms Associated With Schizophrenia And Psychosis, George Vera Jr.

Theses and Dissertations - UTB/UTPA

Polymorphisms in Transforming Growth β-Induced Factor (TGIF) have been found to contribute to the risk of development of psychosis and related disorders. Identifying the genes responsible for causing schizophrenia and psychosis will allow for treatment at an earlier stage of development, saving the patient problems, time, and money. The purpose of this experiment is to determine the haplotype of DNA samples obtained from earlier experiments. The DNA samples were collected from people with schizophrenia in Costa Rica, Southern Texas, and Northern Mexico. The samples were tested using 5 single nucleotide polymorphisms (SNPs) and amplified using polymerase chain reaction (PCR). Haplotypes …


Trace Analysis Of Volatile Organic Compounds In The Water Of The Arroyo Colorado And The Lower Laguna Madre Utilizing E.P.A.Sw846 Method 8260, Humberto Valdez May 2010

Trace Analysis Of Volatile Organic Compounds In The Water Of The Arroyo Colorado And The Lower Laguna Madre Utilizing E.P.A.Sw846 Method 8260, Humberto Valdez

Theses and Dissertations - UTB/UTPA

Volatile organic compounds (VOC) can cause a major environmental concern since they create a hazard to public health and the environment. This study focused on determining concentration of VOCs in Arroyo Colorado waters and the Lower Laguna Madre (LLM) utilizing GC/MS. Little is known on the concentration and composition of VOCs. Toluene was the most common VOC. Concentrations ranged from 0.0010 mg/L to 0.0039 mg/L. Analysis of a sediment pore water sample collected near the mouth of the Arroyo Colorado also detected toluene (0.0023 mg/L). This study showed that VOCs were concentrated near the county boat launch and somewhat downstream. …


An Expeditious Synthesis Of N-Substituted Pyrroles Via Microwave-Induced Iodine-Catalyzed Reactions Under Solventless Conditions, Debasish Bandyopadhyay, Sanghamitra Mukherjee, Bimal K. Banik Apr 2010

An Expeditious Synthesis Of N-Substituted Pyrroles Via Microwave-Induced Iodine-Catalyzed Reactions Under Solventless Conditions, Debasish Bandyopadhyay, Sanghamitra Mukherjee, Bimal K. Banik

Chemistry Faculty Publications and Presentations

An expeditious synthesis of N-substituted pyrroles has been developed by reacting 2,5-dimethoxy tetrahydrofuran and several amines using a microwave-induced molecular iodine-catalyzed reaction under solventless conditions.


Nuclear Quantum Effects In The Structure And Lineshapes Of The N2 Near-Edge X-Ray Absorption Fine Structure Spectrum, Shervin Fatehi, Craig P. Schwartz, Richard J. Saykally, David Prendergast Mar 2010

Nuclear Quantum Effects In The Structure And Lineshapes Of The N2 Near-Edge X-Ray Absorption Fine Structure Spectrum, Shervin Fatehi, Craig P. Schwartz, Richard J. Saykally, David Prendergast

Chemistry Faculty Publications and Presentations

We study the relative ability of several models of x-ray absorption spectra to capture the Franck–Condon structure apparent from an experiment on gaseous nitrogen. In doing so, we adopt the Born–Oppenheimer approximation and a constrained density functional theory method for computing the energies of the x-ray-excited molecule. Starting from an otherwise classical model for the spectrum, we systematically introduce more realistic physics, first by substituting the quantum mechanical nuclear radial density in the bond separation R for the classical radial density, then by adding the effect of zero-point energy and other level shifts, and finally by including explicit rovibrational quantization …


Microscopic And Spectroscopic Studies Of Thermally Enhanced Electrospun Pmma Micro- And Nanofibers, Sean Pelfrey, Travis Cantu, Michael R. Papantonakis, Duane L. Simonson, R. Andrew Mcgill, Javier Macossay-Torres Mar 2010

Microscopic And Spectroscopic Studies Of Thermally Enhanced Electrospun Pmma Micro- And Nanofibers, Sean Pelfrey, Travis Cantu, Michael R. Papantonakis, Duane L. Simonson, R. Andrew Mcgill, Javier Macossay-Torres

Chemistry Faculty Publications and Presentations

Carbon nanofibers (CNFs) have been incorporated into poly(methyl methacrylate) (PMMA) through electrospinning. The resulting micro- and nanofibers have been characterized by Scanning Electron Microscopy (SEM), which confirmed fiber formation and demonstrated a core-sheath structure of the PMMA fibers. Thermogravimetric Analysis (TGA) was used to obtain the thermal properties of the materials, indicating an enhancement in the thermal properties of the composite fibers. In addition, Fourier Transform Infrared Spectroscopy (FTIR) was utilized to investigate the interactions of PMMA micro- and nanofibers with CNFs, demonstrating the preferred sites of intermolecular interactions between the polymer matrix and the filler.


Remarkable Iodine-Catalyzed Synthesis Of Novel Pyrrole- Bearing N-Polyaromatic B-Lactams, Debasish Bandyopadhyay, Gildardo Rivera, Isabel Salinas, Hector Aguilar, Bimal K. Banik Feb 2010

Remarkable Iodine-Catalyzed Synthesis Of Novel Pyrrole- Bearing N-Polyaromatic B-Lactams, Debasish Bandyopadhyay, Gildardo Rivera, Isabel Salinas, Hector Aguilar, Bimal K. Banik

Chemistry Faculty Publications and Presentations

Because of their interesting biological properties various methods for the synthesis of substituted pyrroles are described in the literature. However, synthesis of pyrroles fused with a β-lactam ring has not been reported. Our group has demonstrated synthesis and biological evaluation of various β-lactams as anticancer agents. The anticancer activities of these compounds have prompted us to study the synthesis of pyrroles bound to the β-lactams. We have identified an expeditious synthetic method for the preparation of pyrroles fused with β-lactams by reacting 3-amino β-lactams with acetonylacetone in the presence of catalytic amounts (5 mol%) of molecular iodine at room temperature. …