Physical Sciences and Mathematics Commons^™

Synthesis Of 1-Alloc-Piperidine-4-Fmoc-Amino-4-Carboxylic Acid: A Novel, Protected ?,?- Disubstituted Amino Acid, Muna K. Thalji

Honors Theses

No abstract provided.

Studies Of V, Nb, Cr, And Zr Substituted 2:17 Compounds And Their Carbides Using Neutron Diffraction, H. Luo, Z. Hu, Muguo Chen, William B. Yelon, G. K. Marasinghe, Peter C. Ezekwenna, William Joseph James, W. C. Chang, S. H. Tsai

Physics Faculty Research & Creative Works

Samples of Nd₂Fe_17-xT_xC_y with T=V, Nb, Cr, and Zr were prepared by melting of the constituent elements including C and studied by neutron diffraction. Comparing with their uncarbided counterparts, we found that the substituents transfer, more or less, from the 6c site to the 18f and 18h sites with the introduction of C atoms. This behavior appears to relate to the electronegativities between the C atoms and the early transition series elements because the 18f and 18h sites are near neighbors of the interstitial C site. However, the C effects in the V. …

Magnetic And Structural Properties Of Nd₂Fe₁₇₋ₓmnₓ Solid Solutions, Peter C. Ezekwenna, G. K. Marasinghe, William Joseph James, Oran Allan Pringle, Gary J. Long, H. Luo, Z. Hu, William B. Yelon, Ph. I'Héritier

Chemistry Faculty Research & Creative Works

A series of Nd₂Fe_17-xMn_x solid solutions with x values between 0 and and 6 were prepared and analyzed using magnetic measurements, neutron diffraction, and Mössbauer spectroscopy. All of the Nd₂Fe_17-xMn_x samples crystallized in the Th₂Zn_17-x-type rhombohedral structure. The lattice parameters and unit cell volumes decrease with increasing manganese content up to ∼ x equal to 2, and then increase for higher manganese content. The magnetizations of Nd₂Fe_17-xMn_x decrease with increasing manganese content and Nd₂Fe_17-xMn_x is paramagnetic …

An Analysis Of Iron-Iron Interatomic Distances In Several Rare Earth Transition Metal Intermetallics, G. K. Marasinghe, Peter C. Ezekwenna, William Joseph James, Z. Hu, William B. Yelon

Chemistry Faculty Research & Creative Works

As a part of a systematic study of the dependence of iron-iron exchange interactions on near neighbor iron-iron distances in rare earth transition metal magnetic materials, we have conducted a statistical analysis of interatomic distances in Nd₂Fe₁₇, Nd₂Fe₁₇N₃, and Nd₂Fe₁₄B. Results, in general, support the notion that larger near neighbor iron-iron distances promote higher Curie temperatures. In this work, special attention has been paid to the expansion of the Nd₂Fe₁₇ lattice due to interstitial nitrogenation and the accompanying increase in the Curie temperature. …

Synthesis And Characterization Of Modified Silica Gel As An Intermediate In The Generation Of Gaseous Standard Mixtures, M. Prokopowicz, K. Lewandowska, A. Skwierawska, Andrzej Przyjazny, Jan F. Biernat, J. Namiesnik

Chemistry & Biochemistry Publications

A possibility of extending analytical applications of chemically modified silica gels is described. This involves their utilization for the generation of gaseous standard mixtures consisting of methyl chloride as the analyte and nitrogen as a carrier gas to be used for the calibration of the GC-FID system. N-methylmorpholine was chemically bonded to the propylsilylated surface of silica gel forming chloride of an appropriate immobilized compound which, under certain conditions, undergoes thermal decomposition yielding a single, volatile component (methyl chloride). Such a method of generating specific amounts of a standard substance can be used both for a single point calibration and …

Mechanistic Studies On The Aminopeptidase From Aeromonas Proteolytica:  A Two-Metal Ion Mechanism For Peptide Hydrolysis, Guanjing Chen, Tanya Edwards, Ventris M. D'Souza, Richard C. Holz

Chemistry Faculty Research and Publications

The aminopeptidase from Aeromonas proteolytica (AAP) is uncompetitively inhibited by fluoride ion at pH 8.0 with an inhibition constant (K_i) of 30 mM. Thus, fluoride inactivates AAP only after substrate binding, and only a single fluoride ion binds to AAP. On the other hand, chloride ion does not inhibit AAP up to concentrations of 2 M at pH 8.0. The pH dependence of fluoride inhibition of AAP was measured over the pH range 6.0−9.5. Between pH values of 6.0 and 9.0, fluoride ion acts as a pure uncompetitive inhibitor of AAP, and the K_i increases from …

Dipole Spectroscopy, Ronald Lovett

Topics in Quantum Mechanics

No abstract provided.

Fragment Rotational Distributions From The Dissociation Of Nebr2: Experimental And Classical Trajectory Studies, Mehdi Nejad-Sattari , '95, Thomas Alex Stephenson

Chemistry & Biochemistry Faculty Works

The Br-2 fragment rotational distributions that result from the vibrational predissociation of NeBr2 in the B electronic state have been measured for several initial vibrational levels. In each case, the rotational distributions extend to the effective energetic Limit determined by the amount of energy available (E(av1)) for disposal into the fragment rotational and translational degrees of freedom. Analysis of the data allows refinement of the NeBr2 dissociation energy; we find that D-0=70.0 +/- 1.1 cm(-1) for the X electronic state, v = 0. Both Delta v = - 1 and -2 dissociation events have been examined. For dissociation pathways with …

42. Kenichi Fukui, Otto Vogl, Tetsuki Yamaoka

Otto Vogl

No abstract provided.

Analysis Of Organic Nitrates In Artic Outflow, Deanna Elyea-Piper

Masters Theses

The Arctic Outflow Study (AOS) was a project funded by the National Science Foundation to assess the impact of tropospheric ozone concentrations by the measurement of oxidized nitrogen. Measurements of arctic outflow were made to assess the seasonal cycle of compounds in arctic air and the partitioning of NOy during transport to the North Atlantic region. These photochemically active compounds are elevated in the arctic during the winter and spring because of the lack of photochemical processes to destroy them.

Measurements of PAN, Alkyl nitrates, NOy, NO, NO₂, CO, HNO₃, O₃, and particulate nitrate …

Thermal Studies Of Complex Formations Of First Row Transition Metals With Phenolic Compounds In Aqueous Solution, Nabil Adnan Amro

Masters Theses

The coordination chemistry of protocatechuic acid and catechols with the first row of transition metals was studied as a model for the more complicated natural humic substance.

The reaction between Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ and the phenols, catechol and protocatechuic acid in aqueous solution was studied by the spectrophotometric method. The composition of the complexes formed was determined by continuous variation, iso-molar series and molar ratio methods. The presence of complexes with metal:ligand ratio of 1:1, 1:2 and 1:3 was established in the pH range 3 to …

Rounding Numbers: Why The ''New System'' Doesn't Work, W. Robert Midden

Chemistry Faculty Publications

This paper explains a correction to the rounding rule previously publishedin this Journal. The earlier article reported that the best way to roundnumbers is to always round up when the first digit dropped is 5. However,this will lead to accumulation of error when errors are averaged. Arounding strategy that leads to less error is to round up when 5 isfollowed by any nonzero digits, but to round even when 5 is followed byzeros or no other digits. By rounding the last kept digit to an evennumber, half the time the digit is increased and half the time it is keptthe …

Development Of Solid Phase Microextraction Methods For Contraband Drugs, Vangielynn Cruz Tersol

Chemistry & Biochemistry Theses & Dissertations

The objective of this study is to develop analytical methods for studying contraband drugs at nanogram levels and to demonstrate the utility of the methods. A method which combines solid phase microextraction with ion mobility spectrometry (SPME-IMS) was developed. The SPME-IMS method was used as a rapid screening tool in studying the chemistry of cocaine HCI, heroin HCI, and heroin freebase on surfaces. The total time for sample preparation, reaction, and analysis is approximately seven minutes. Another method that was developed is one that combines solid phase microextraction with gas chromatography (SPME-GC) for the quantitative analysis of cocaine freebase and …

Development Of A Fluorescent Indicator For Inorganic Monochloramine, Xiaojun Dong Zou

Chemistry & Biochemistry Theses & Dissertations

Current methods used to determine combined residual chlorine cannot distinguish between inorganic monochloramine (NH₂Cl) and organic chloramines. Studies described in this thesis were carried out to develop a novel method of determining the concentration of inorganic monochloramine in aqueous solutions. Based on the observation that the reaction of 3-formyl-1-methylpyridinium chloride (3FMPCl) with NH₂Cl produces a solution which is fluorescent, experiments were conducted to characterize the reaction and optimize the experimental conditions. Using the finalized protocol, NH₂Cl measurements were made in the presence and absence of organic amines and compared with a commonly used N, …

43. Karl Kratzl, Otto Vogl

Otto Vogl

No abstract provided.

An Electrical Resistivity Study Of Ce₂Fe₁₆.₈ And The Ce₂Fe₁₇₋ₓalₓ And Ce₂Fe₁₇₋ₓsiₓ Solid Solutions, Denis Vandormael, Fernande Grandjean, Hassan Bougrine, Marcel R. Ausloos, D. P. Middleton, K. H. J. Buschow, Gary J. Long

Chemistry Faculty Research & Creative Works

Electrical resistivity measurements have been carried out between 20 and 300 K on Ce₂Fe_16.8, on the Ce₂Fe_17-xAl_x. solid solutions, with x = 0.4, 1, 2, 5, 6, 8, and 9, and on the Ce₂Fe_17-xSi_x solid solutions, with x = 0.2, 0.4, 1, and 2, with the four probe method. The temperature dependence of the resistivity of Ce₂Fe_16.8 shows an inflection at 110 K, a feature which is also observed in the temperature dependence of the magnetization and is related to a magnetic …

Electrochemical Studies Of Spinel Limn 2o 4 Rechargeable Lithium Battery, Li Feng, Yuqin Wu Lie Chang, Hong Li, Yibin San, Tianhong Lu

Journal of Electrochemistry

The spinel Li intercalation compound LiMn 2O 4 was prepared and studied using ac impedance and cyclic voltammogram techniques. It was first discussed that the impedance behaviors of LiMn 2O 4 electrode varied as lithium ion was intercalated in or out the electrode with the help of fractal theory. The Li reversible behaviors in LiMn 2O 4 electrode were shown by the cyclic voltammogram results.

A Study On The Electrodeposition Of Palladium And It′S Nucleation, Fangzu Yang, Shukai Xu, Shibing Yao, Bingyi Chen, Xueqing Zheng, Xiaohui Zhong, Shaomin Zhou

Journal of Electrochemistry

The electrodeposition and nucleation of palladium are studied in the system of potassium citrate and ammonium oxalate. The results show that, with the additives of XP 4 and XP 7 prepared in our laboratory, a full bright palladium electrodeposits will be obtained in the wide ranges of the cathode current densities 0.5～3.5 A/dm 2 and temperature 40～60 ℃; the qualities of the thick deposits will be effectively improved by means of pulse current plating. Cyclic voltammograms results show that the division of peaks between anodic and cathodic on the electrode process of palladium will be up to 1.05 V, which …

Ac Electrochemical Thermal Method For Investigating The Entropy Change Of Electrochemical Reaction, Liangjun Dong, Jihua Zhuang, Zhiyu Jiang

Journal of Electrochemistry

An ac electrochemical thermal method was developed for measuring the entropy change of the electrochemical reaction. When an ac current i 0 cos ωt passed through an electrode in the solution, the heat produced at the surface consisted of several parts. The part varied with frequency ω was caused by the entropy change of the electrochemical reaction, so called the Peltier heat. It could be measured by using a pyroelectric PVDF film detector with a lock in amplifier. This method presents the advantage to inhibit the influence of the polarization heat and Joule heat. The entropy changes of electrochemical reactions …

Study Of The Nature Of Formic Acid Adsorbates On Rough Pt And Its Interaction With Co, Xia Xinhua, Iwasita T., Vielstich W.

Journal of Electrochemistry

The nature of formic acid adsorbates formed on porous platinum electrode has been studied by in situ infrared reflectance spectroscopic (FTIR) and differential electrochemical mass spectroscopic (DEMS) techniques. By carefully avoiding the contamination of the environment( i.e ., air) voltammetric experiments show that the oxidation of formic acid adsorbates depends on both adsorption potential and adsorption time. The online DEMS results show furthermore that the number of electrons necessary for the formation of one molecule of CO 2 from adsorbed formic acid is independent of the adsorption potential. Its value of 2.2 demonstrates that the composition of formic acid adsorbates …

Electrochemical Synthesis And Characterization Of Ba Pb O And Bi Pb O Oxides, Min Zhao Liangzhong Xie, Cuiying Xu, Jinbiao Zhang

Journal of Electrochemistry

Pb based oxides Ba Pb O and Bi Pb O were synthesized from aqueous solutions by using electrochemical method. The resulting Ba Pb O and Bi Pb O were characterized using XPS, EDX and XRD. The results show that perovskite BaPb 0.9 O 3 can be electrodeposited on the anode only from strong alkaline solution. In acid aqueous solution, conducting BiPb 2O z oxide is fromed on the anode. In these oxides the nominal valence of lead is +4.

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

Journal of Electrochemistry

The interstitial liquid among the particles in anodic Pb(Ⅱ) films could be the major passage for ion transportation. This is discussed with the mechanism of the cathodic reduction of anodic PbSO 4 film and the effect of Sb on the growth of anodic Pb(Ⅱ) oxides film.

Electrochemical Behaviors Of Isoalloxazine Confined In Montomorillonite Olay Modified Electrode, Zhibin Wu, Yuan Lin, Daodao Zhang, Haoqin Wu

Journal of Electrochemistry

A cyclic voltametric investigation of stability and redox properties of isoalloxazne on cetytrimethyammonium bromide(CTAB) modified montomorillonite clay platinium electrode in aqueous solution has been performed. pH dependent film concentrations and apparent diffusion coefficents were measured. The mechanism of the charge transport process with in the clay film were discussed.

Study On The Hydrophilicity Of Nafion Membrane Surface, Yanbing Zu, Chuansin Cha

Journal of Electrochemistry

Due to its high chemical stability and ion selective permeability, Nafion membrane has been applied in many electrochemical systems. The surface hydrophilicity is one of the main factors affecting its performance. In this paper, the bound bubble method is introduced as a suitable way to measure the contact angles between Nafion membrane and various aqueous solutions. During the measurement, Nafion membrane is saturated with given electrolyt solution. The hysteresis of the contact angles observed in the measurement is attributed to the co existance of hydrophobic and hydrophilic domains at the membrane surface. The effect of the solution surface tension on …

The Adsorption Desorption Behaviors Of Β Phenylaminopropiophenone On Iron In Sulphuric Acid Solution, Xianzhang Bu, Dihua Wang, Jinyun Zou, Fuxing Gan

Journal of Electrochemistry

The adsorption desorption behaviors of β phenylaminopropiophenone (PAP) on iron in 0.5 mol·L -1 H 2SO 4 solution with or without halide ions (Cl -,I -) were investigated by potentiostatic polarization measurement. The results show that the adsorption of PAP on iron surface follows Flory Huggins isotherm, the adsorption free energy parameter ( f ) is positive in H 2SO 4 solution; In the presence of 0.1 mol·L -1 Cl -1 , when C PAP ≤2×10 -5 mol·L -1 , f<0 and when C PAP ≥5×10 -5 mol·L -1 , f>0 . A desorption phenomenon was observed at more positive potential region in anodic polarization curves. Furthermore, the anodic …

Studies On The Cathodic Current Efficiency In The Electrodeposition Ni Psz Gradient Coating, Jun Li, Dianlong Wang, Li Chen, Xinguo Hu

Journal of Electrochemistry

The cathodic current efficiency and the electrochemical behavior in electrodeposition Ni PSZ gradient coating were investigated by various electrochemical techniques and scanning electron microscope. The results showed that the Ni PSZ composite coatings can accelerate evolution of hydrogen with the increase of PSZ content. The overpotential of nickel reduction will be increased and that of hydrogen reaction will be reduced in the presence of PSZ particles in electrolyte. The effect of PSZ particles on nickel electrodeposition was preferentially to catalyze the formation of H ads . These all contributed to the lower current efficiency.

Study On Properties Of Magnesium Alloy Electrode With Anodized Film, Yi Chi, Ping Yang, Xiufeng Lin

Journal of Electrochemistry

The corrosion resistance of Mg alloy electrode with anodized film in atmosphere is bigger than that of the Mg alloy electrode with chromate film. The corrosion resisance and voltage delay of such electrode with anodized film in NaCl solution changed with anodizing comdition. The effects of composition, morphology and thickness of the anodized film on the peoperty of Mg alloy electrode are discussed.

Surface Modifications Of Carbon Materials Used As Anode Of Lithium Ion Batteryⅱ.The Carbon Material With Core Shell Structure And Its Positive Effect On Cell Performance Of Graphite Anode, Shuhua Ma, Hanju Guo, Ji Li, Hongze Liang, Xiabin Jing, Fosong Wang

Journal of Electrochemistry

The carbon powders and film electrode with core shell structure were prepared by carbonization in gas state with using refined coal as shell material and Artificial Graphite and Mesocarbon Microbeads (2 800 ℃) graphite as core material. Galvanostatic charge/discharge measurement showed that both steady charge/discharge capacity and first charge/discharge efficiency were improved. Cyclic voltammetry indicated that the peak at about 0.7 V vs. Li +/Li characteristic of decomposition of electrolyte got weakened, and a more compact film was formed. X ray diffraction measurement suggested the existence of amorphous carbon shell on the carbon powders and carbon film.

Status Of Electroplated And Electroless Plated Thin Film Media For Magnetic Recording, Maozhong An, Zhelong Yang, Jingshuang Zhang, Zhenmi Tu

Journal of Electrochemistry

The current study situation for the magnetic recording media films produced by electroplating and electroless plating at aboard was summarized. The bath composition and operating conditions, the properties of the films were introduced. The problem to be solved for extending application of the films was suggested and thd further development was expected.

Co Wc Composite Elecrode, Zeshan Zhu, Xiufeng Xiao, Rongfang Liu, Jingying Shi

Journal of Electrochemistry

Electrodepositing Co WC composite coatings from cobalt electro bath including WC particles was studied. WC particles accelerate the cathode reaction of composie electrodeposition. In alkaline solution the electrocatalytic properties of evoluting hydrogen were investigated. The results show that the properties of electrode remain superior and stable in a long term interval electrolyzing experiment.