Physical Sciences and Mathematics Commons^™

Synthesis Of Higher Α-Chlorovinyl And Α-Bromovinyl Amino Acids: The Amino Protecting Group Determines The Reaction Course, David B. Berkowitz, Michelle L. Pedersen, Wan Jin Jahng

Chemistry Department: Faculty Publications

N-Trifluoroacetyl α-vinyl amino esters are smoothly converted to the corresponding α-chlorovinyl or α-bromovinyl amino esters through the agency of phenyselenyl chloride or phenylselenyl bromide, respectively, followed by oxidation and pyrolysis. Exclusively the (E)-extemal halovinyl isomer and the internal halovinyl isomer are observed. The amino protecting group is a critical determinant of the reaction course (alkene addition vs. 5-exo-trig-like cyclization).

Experimental Evidence For Self-Similar Structures In The Aggregation Of Porphyrins In Aqueous Solutions, F. Mallamace, N. Micali, S. Trusso, L. M. Scolaro, A. Romeo, A. Terracina, Robert F. Pasternack

Chemistry & Biochemistry Faculty Works

We have studied the aggregation of the porphyrin t-H₂Pagg in aqueous solution by light scattering. The intensity profile of the elastically scattered light, studied in the exchanged wave-vector range 0.2 ≤ q ≤ 31.4 μ m⁻¹, indicates that the aggregation produces large monodisperse clusters having a fractal structure, and is driven by diffusion-limited aggregation kinetics. Additional measurements performed at different q values confirm such a picture giving a hydrodynamic radius R(H) consistent with the radius of gyration R(g) measured by elastic scattering. This is explained taking into account the q² dependence observed in the mean decay rate of the intensity-intensity …

Cleavage Of Dna By The Insulin-Mimetic Compound, Nh4[Vo(O2)2(Phen)], Catharina Hiort, Jerry Goodisman, James C. Dabrowiak

Chemistry - All Scholarship

The kinetics and mechanism of cleavage of DNA by the insulin-mimetic peroxo-vanadate NH4[VO(O2)2(phen)], pV, are described. In the presence of low energy UV radiation or biologically common reducing agents, pV decomposes into the monomer, dimer, and tetramer of vanadate and an uncharacterized compound of V4+ as shown by 51V NMR, ESR, and absorption spectra. The rate of photodecomposition of pV is reduced in the presence of calf thymus DNA, indicating that a decomposition product of the peroxo-vanadate, that is important in the destruction pathway of the complex, is interacting with DNA. This species, probably a short-lived complex of V4+, may …

Determination Of Conditions For Oye In Which There Is No Ion Present In The Active Site, Melissa J. Morris

Honors Theses

Old Yellow Enzyme (OYE) has been the subject of extensive research since the early 1930's. However, the structure of OYE was not determined until 1994, and its physiological function still remains a mystery. Investigations into the function of OYE involve uncovering the details of protein-substrate interactions through the use of x-ray crystallography. OYE is known to oxidize NADPH, but attempts to crystallize the OYE-NADPH bound complex have been hampered by the presence of chloride in the active site of OYE. This competition prevents an accurate assessment of the structure of OYE bound to NADPH. This study will examine the possibility …

51. Ephraim Katchaski-Katzir, Otto Vogl, Joseph Jagur-Grodzinski

Otto Vogl

No abstract provided.

Inclusion Processes Of Cyclodextrins And Their Polymers: A Molecular Modeling Study, Stacey L. Fellows

Honors Theses

Cyclodextrins (COs) and cyclodextrin polymers (CDPs) are molecules capable ot creating host/guest complexes, where a host molecule allows another molecule, a guest, to bind to it without either molecule losing its molecular identity. CDs are hydrophilic t,, 11, contain a unique hydrophobic cavity that can attract organic guest molecules. CDP is a derivative of CD and consist of two or more CD units connected by chains of glyceryl linkages (-CHrCHOH-CH2-O-). CDPs are typically more hydrophilic- than the CD monomers making them more useful for applications. However, behavior of the CDP is not as well-cinderstood as that of the monomer. Computer …

Design And Application Of A Compact, Multipurpose, Laser-Based Spectrometer, Andrew M. Leach

Honors Theses

A compact laser-based spectrometer has been designed and characterized. This design of this instrument gives it the ability to collect absorbance, fluorescence, and scattering signals simultaneously. A diode laser is used as the excitation for this instrument. Several optical arrangements have been tested in order to allow for the best possible signal collection. Electronics have been designed and constructed in order to facilitate the simultaneous collection of signals. This instrument has been characterized using several dyes and scattering agents. Fluorescence limits of detection for Methylene Blue and Nile Blue A have been calculated at 2 ppb. The spectrometer has been …

Flow Injection Analysis With A Laser-Based Detector For On-Line Determination Of Sulfide, Glucose, And Ethanol, Manisha Tinani

Honors Theses

In this research a flow injection (FI) apparatus with a laser-based detector is characterized using three chemical systems and the results are compared to those obtained by other researchers using conventional instrumentation. Each chemical system involves Methylene Blue (MR), a common redox indicator. A 670-nm diode laser is used as the excitation source, and the resulting fluorescence is measured. In the first system, MB is formed as a product of the reaction of N,N-dimethylphenylenediamine (DMPD), iron (lll) and sulfide in the presence of acid. A three-line FI manifold is employed. The amount of sulfide in water samples, including a complicated …

The Crystallization Of Estrogen-Binding Protein, Jeffrey R. Weinstein

Honors Theses

Candida albicans is a yeast that is known to target humans with weakened immune systems. The growth rate and invasiveness of C. albicans is stimulated in the presence of estrogens. Experimental evidence suggests that the estrogen-binding protein (EBP) from C. albicans may be involved in the estrogen-induced increase in growth rate. In order to investigate the possible involvement of EBP in this process, work is underway to determine the atomic structures of EBP alone and bound to estrogen. Protein crystals of EBP have been grown at 4°C in the presence and absence of estrogen using vapor diffusion techniques from a …

Synthesis And Characterization Of Β-Cyclodextrin Polymers, Jodie L. Iannacone

Honors Theses

Cyclodextrin polymers (CDPs) are water Joluble polymers composed of either a, fl, or y cyclodextrin (CDl monomers. TI,ese commercially available polymers are synthesized ming epichlorohydrin and consist of CD monomers joined by repeating glycer;l linkers (-(CH2-CHOH-CH2-ln) with an average n value of 12-15. GPC analysis of these polymers indicate two major component peaks that have molecular weights (MW) of 2,000 (one CD/ polymer chain) and 9-10,000 (4-5 CDs/polymer chain). These polymers have been used to study the binding interactions of various fluorescence probes. It has been shown that the pyrene fluorescence lifetime increases and its emission I/III ratio decreases in …

Introduction Of The Gas Chromatograph Into The Introductory Chemistry Laboratory, Jonathan Calvert Wedvik

Honors Theses

No abstract provided.

A Graph Theoretic Study Of The Similarity Of Discrete Structures, Heather D. Gavlas

Dissertations

A basic problem in drug design consists of finding a compound that satisfies a spectrum of biological and chemical properties. Although drug design problems are central to pharmaceutical research, statisticians have yet to become involved in this area as these problems are viewed statistically as optimization problems. Before statistical optimization procedures can be defined on these spaces whose points are structures and not vectors, very basic mathematical notions of distance must be defined. Graphs have been used as mathematical models to represent the bonding arrangements of molecules for quite some time. In fact, if some of the methodology used by …

Flash Photochemical Kinetics Of Chromium Carbonyls, Jason David Katz

Honors Theses

Chromium hexacarbonyl, Cr(C0)6, has been shown to be a very effective photochemical catalyst for many reactions, such as the 1,4- hydrogenation and 1,4-hydrosilatlon of conjugated 1,3-dienes resulting in the formation of a cis alkene product in greater than a 99% percent yield. The catalytic power of Cr(CO)6 has merited its study by many investigators, mostly with regard to the structure of the catalytic intermediates, rather than the actual kinetics of individual steps in the mechanism. The goal of this study is to construct a database of both rate and mechanistic information on the reactions of Cr(CO)6 with various alkenes and …

An Investigation On Nonenzymatic Autoxidation Of Phenolic Compounds In Natural Waters, Lei Jiang

Masters Theses

The nonenzymatic autoxidation of the phenolic compounds chlorogenic acid in aqueous solution was studied. The study demonstrated that the oxidation rate of chlorogenic acid was strongly dependent on pH. The higher the pH, the faster the rate of oxidation. The involvement of phenolate ions and radicals in oxidation reactions are two possible reasons for the pH dependency. The presence of a trace amounts of reducible transition metal ions, such as copper(II), dramatically increases the oxidation rate of chlorogenic acid. Light also increases the oxidation rate of chlorogenic acid. However, the photochemical reaction was a much slower process.

The TLC and …

The Reactions Of Nox With Diesel Soot Over Cu-Zsm-5 Catalyst, Shu Sun

Theses

Air pollution from the exhaust of Diesel engines consisting of relatively high concentrations of NO_x and particulates is a difficult problem to overcome because no fully effective technology to control these emission is available. The existing methods to reduce NO_x and soot can not satisfy the provisions of the 1990 CAAA (Clean Air Act Amendment). Cu-ZSM-5, a catalyst in which Cu has been ion-exchanged with H+, can catalyze the decomposition of NO to N₂ and O₂ and reduction to N₂ and O₂ with light hydrocarbons such as propene or Diesel soot in the presence …

Speciation And Determination Of Trace Lead : Methodology Development And Analysis Of Natural Waters Using Chelex-100 And Gfaas, Xidan Ma

Theses

The development of a method for speciation, preconcentration, and determination of lead was successfully conducted using Chelex-100 and graphite furnace atomic absorption spectroscopy (GFAAS). Sorption under static conditions and direct measurements in the bead slurry or after fast elution of lead from beads with HNO3 solution was used. The effects of buffers, sorption kinetics, filtration criteria, sample concentration, resin particle size and temperature program for the GFAAS were carefully studied. In this study, synthetic aqueous samples containing lead were preconcentrated under static conditions using the ion exchange resin, Chelex-100, and the resin was directly analyzed using GFAAS. The batch preconcentration …

Electroluminescent Property Of N Type Porous Si And Its Characterization By Xps And Lima, Guozheng Li, Chenqian Zhang

Journal of Electrochemistry

The chemical composition and structure of electroluminescent porous Si(PS) on n Si, prepared by photoelectrochemical etching method, were investigated by using XPS and LIMA. The results show that electroluminescence(EL) intensity depends on the formation potential of PS. The relation between EL property and the results of XPS and LIMA is also discussed.

The Reduction Of Oxygen To Hydrogen Peroxide In An Acidic Trickle Bed Cell Using Graphite Chip Cathode, Zhaoe Lu, Guanyong Zhang, Tiangeng Zhong, Guonu Fang

Journal of Electrochemistry

The authors investigated the electrochemical reduction of oxygen to hydrogen peroxide in 0.05 mol/L H 2SO 4 solution by the trickle bed electrode using graphite chip. The bed dimension was 14×5×0.6 cm. The current efficiency and the concentration of H 2O 2 in the catholyte were determined at various current strengths and various rates of adding the electrolyte. The proper current was 0.15 A. i.e. the current density was 2.1 mA/cm 2 vertical cross section area of the bed. The concentration of H 2O 2 reached 7×10 -3 mol/L with the current efficiency of 0.2. If the concentration of H …

Electrocatalytic Reduction Of Nitrite In The Presence Of Complex Of Cobalt(Ⅱ) And 1,10 Phenanthroline, Jian Tong, Xiaojun Dang, Hulin Li

Journal of Electrochemistry

The electrochemistry of cobalt(Ⅱ) 1,10 phenanthroline Co(Phen) 2+ 2 complex and its ability to electrocatalyze the reduction of nitrite were studied , we found that this complex could act as a catalyst in alkaline or neutral solution for nitrite reduction. We have investigated the effect of the complex composition on electrocatalytic ability. The effects of pH value, complex concentration, regeneration and activation of electrocatalyst on the catalytic current have been studied and discussed.

The Electroless Nickel For Aluminium Honeycomb Shielded Vent Windows, Ronghua Wang, Jiaqian Bu

Journal of Electrochemistry

This report summarizes the electroless plating process of magnetic nickel and noncrystalline nickel for aluminium honeycomb shielded vent windows. The test results showed that the electroless nickel plating is bright in appearance, even in thickness, excellent in adhesion with aluminium substrate, good in conductivity, magnetism and corrosion resistance. Shielding efficiency obtained was 67～78 dB under 4 GHz～12 GHz frequency. Environmental reliability tests were made for 56 days under two environmental conditions, that is at 85 ℃ and 35 ℃, 95% relative humidity. The EMI shielding technical requirements of the electroless double nickel plating for aluminium honeycomb shielded vent windows of …

Effect Of Halide Ions On The Deposition Of Electroless Nickel, Keping Han, Jingli Fang

Journal of Electrochemistry

The effect of halide ions on the polarization curves and stationary potential of electroless nickel plating process were studied with electrochemical methods. The acceleration and stabilization mechanism of electroless nickel deposition by halide ions also has been discussed.

Study On Electrode Constructure And Electrical Performance Of Na/S Cell, Jianhua Yang, Jiadi Cao

Journal of Electrochemistry

A sodium wick for sodium electrode and trough shaped performs for sulfur electrode in Na/S cell were designed and investigated. The experiments suggested that the sodium wick for sodium electrode not only improved the discharge performance of cell but also reduced the quantity of sodium utilization, and increased the specific energy of Na/S cell. The trough shaped preform with alumina fibres for sulfur electrode decreased the polarization, improved the charge acceptance and prolonged the life of cell.

The Applications Of Poap Ni 2+ Films Modified Electrode As Sensor For Alcohol, B.Z.Hua Hua, W.Y. Hu, Y.Z.Chen Y.Z.Chen

Journal of Electrochemistry

POAP Ni 2+ films modified electrode can electrocatalyzes significantly the oxidation of alcohol. the modified electrode can be used as the electrochemical sensor for the detection of alcohol. But the oxidation of alcohol is effected by the thickness of films、the concentration of nickel ion in films、pH of electrolyte,as well as temperative. All of those conditions have been studied in order to achieve stable response current during the oxidation of alcohol, and the relation between concentration and current has been made. At last the major characteristic parameters, such as the low limitation of concentration、the response time、the ability of antiinterference et al,have …

Corosion　Potential　Imagingat　The　Interfaceofcoating／Metalbyanewelectrochemicaltechnique, Chang-Jian Lin, Xiang-Dong Zhuo, Ji-Dong Chen, Hui Wang, Rong-Zong Hu, Yi Song, Jian-Guang Tan

Journal of Electrochemistry

No abstract provided.

Problems On The Study Of Anodic Films On Pb In Sulfuric Acid Solution(Ⅱ), Houtian Liu, Qunzhou Wang, Yongqin Wan, Weifang Zhou

Journal of Electrochemistry

The conditions for the growth of the different phases in the anodic Pb(Ⅱ) film on Pb in sulfuric acid solution were discussed.

Status Of The Research And Development For Fuel Cell Technology Abroad, Naichao Li, Baolian Yi

Journal of Electrochemistry

Status of the research and development for fuel cell technology abroad was overviewed,and at the aim of accelerating the research and development for fuel cell technology in China, the corresponding stategy for our country was recommended.

Electrocatalytic Oxidation Of Some C 2 Compounds(Alcohols, Aldehydes, And Carboxylic Acids) On A Pt/Sb Ad Electrode, Hong Li, Lincai Jiang, Xiong Jiang

Journal of Electrochemistry

The electrocatalytic oxidation behavior of some C 2 compounds(alcohols, aldehydes and carboxylic acids) on a Pt/Sb ad electrode prepared in situ or ex situ UPD was investigated using pontential sweep and rotating disc electrode methods. It is confirmed that Pt/Sb ad electrode show the most electrocatalytical active to the oxidation of aldehyde functional group and only a little activity to the oxidation of hydroxyl group, but no activity for the oxidation of carboxyl group. The experimental results show that the activity of the Pt/Sb ad electrode prepared by ex situ UPD is higher than that prepared by in situ UPD. …

Oxygen Charge Transfer Reaction At The Pt/Ysz Interface, Yi Jiang, Wenzhao Li, Jingwang Yan, Shizhong Wang

Journal of Electrochemistry

Oxygen Charge transfer reaction has been investigated by various degrees of potential polarization at the Pt/YSZ interface. Anodic and cathodic charge transfer coefficients were found to be unity over the wide range of oxygen partial pressures and temperatures. While the exchange current density of the interface was found dependent on the partial pressure of oxygen in accordance with the relation: i 0=2FK r(K O 2 P O 2 ) 1/4 (1+K O 2 P O 2 ) 1/2 . Several important parameters, such as electrochemical rate constant, equilibrium constant of oxygen adsorption on Pt surface had also been extracted.

In Situ Studies Of Copper Electrodepostion On Hopg By Using Ecstm, Zhaoxiong Xie, Bingwei Mao, Xiangdong Zhuo, Jiqian Mu, Zhaowu Tian

Journal of Electrochemistry

In this paper, copper electrodepostion on HOPG had been in situ studied by using a homebuilt electrochemical scanning tunneling microscopy (ECSTM). Three dimensional nucleation and subsequent growth of copper crystals were found as the initial stage of copper deposition on HOPG. In the case of lower overpotential or lower concentration of Cu 2+ , the bulk deposited copper layer tended to form smooth terraces, and grow at the edge of steps. The terraces were stable to some extent, which made it possible to be observed with atomic resolution. At a higher overpotential, the crystal size of copper were somehow smaller. …

Studies Of Surface Treatment Methods And Their Operating Mechanisms For Activation Of Hydrogen Storage Electrode, Ronghui Hu, Hanxi Yang, Shigang Lu, Shengxian Li, Jingcheng Liu, Chongzhi Yang

Journal of Electrochemistry

Surface treatment methods by use of charge discharge cycling, KBH 4 reduction and KOH etching were parallely investigated for the rapid activation of Mn(NiCoMnAl) 5 electrode. It is found that the MH electrode treated with hot and concentrated KOH solution exhibits rapid and full activation, and also gives lower discharge overvoltage, higher stable capacity and improved cycleability. It is also revealed from SEM, EDAX and ICP analysis that the KOH activation of the electrode proceeds mainly through the enrichment of mischmetal and nickel in surface to form electrocatalytically active surface for hydrogen absorption reaction, but the surface modification with KBH …