Computational Chemistry Commons^™

Kinetics Of Proteolyic Enzymes Monitored Online With Mass Spectrometry, Jennifer L. Rutherford

Theses, Dissertations and Capstones

On-line reaction monitoring using electrospray ionization mass spectrometry was investigated with the goal of kinetically distinguishing the isomeric amino acids leucine and isoleucine. Leucine and isoleucine are isomers of identical mass (113.0946 Da) which are impossible to distinguish by their mass-to-charge ratios. These isomers are a source of ambiguity when sequencing peptides with exoproteases and mass spectrometry. Here we investigated the kinetics of on-line enzymatic reactions involving exoproteases for differentiating between leucine and isoleucine.

The kinetics of the stepwise exopeptidase degradation of 12 leucine/isoleucine isomeric peptides was monitored in real-time with a Finnigan Mat LCQ with an electrospray ionization source. …

An Eis Study On The Synergetic Filming Between Cathodic Protection And The Corrosion Inhibitor, Yong-Tao Zhao, Jian-Hua Wu, Jian-Hua Qian, Hui Yu

Journal of Electrochemistry

The electrochemical impedance spectroscope (EIS) of 907A steel in seawater was investigated to study the film formation and destruction. The corrosion protection mechanism of the synergy interaction between cathodic protection and YKI-5 corrosion inhibitor (a mixture of polyhydric alcohol phosphate ester, phosphate and polyphosphate) is discused. Typical EIS spectral changes were clearly observed during the film formation and destruction processes. EIS results indicated that the film seemed to formed a multi-layered structure which consist of an inner layer (this may be an inhibitor-metal complex layer) and many outer layers of calcareous deposits. The film possesses of good persistency under the …

Direct Electrolysis Of Seawater On Conducting Film For Microbial Anticorrosion 1. Simulation And Measurement Technique, Wei-Ling Hu, Ling-Ling Wu, Jing Zhou, Jing-Xin Li, Jin Luo, Zhong-Hua Lin

Journal of Electrochemistry

Based on the electrochemical micro probe and the weak signal detection technique, simulated test and measurement system were set up by the use of four-electrode cell(including a micro electrode), bipotentiostat, lock-in amplifier and three-dimensional micro manipulating device. Based on the system, the micrometer scale concentration distribution of trace hypochlorite, which is produced by direct electrolysis of seawater on the conducting film for preventing microbial corrosion has been obtained for the first time. Both relationships between concentration of hypochlorite and its reduction current, which is termed an working curve, and between the reduction current of hypochlorite and measured time are reported.

Effects Of Nickel Content And Simulated Heat Affected Zone Of 2205 Duplex Stainless Steel On Pitting Corrosion, Horng-Yih Liou, Ju-Tung Lee, Wen-Ta Tsai, Rong-Iuan Hsieh, Yeongtsuen Pan

Journal of Electrochemistry

The effects of nickel content and Gleeble simulated heat affected zone (HAZ) of 2205 stainless steel on pitting corrosion were investigated in this paper. The results showed that nickel content, ranging from 4.5 wt% to 6.5 wt% in base metal, had only a minor effect on the electrochemical polarization curves, with all E_np's and E_pp's falling in the rang of 1100~1200 mV. Comparing with the base metal, the simulated HAZ microstructure caused an increase in the anodic current density, a distinct decrease in both E_np and E_pp , and a reduction in the passive …

Some Electrochemical Studies On The Bionic Nereistoxin Pesticide-(Ch3)2Nhch(Ch2S2O3)2Na⋅H2O, Chang-Geng Zhang

Journal of Electrochemistry

A study of cyclic voltammetric behavior of the nereistoxin pesticide known as Shachongdan is reported. The effects of scan rate, electrolyte pH, and concentration are discussed.The study shows that this electrode process is an irreversible electrode reaction. The saturate adsorption of dihydronereistoxin on the electrode is also discussed with the saturate adsorption amount of 8.23×10^-10 mol/cm².

Study On Steel Corrosion In Simulated Biofilm Environment In Seawater, Qing-Fei Wang, Jing Sui, Run-Xi Su, De-Ying Kong, Shi-Zhe Song

Journal of Electrochemistry

Biofilm is one of the main factors that influence metal corrosion in seawater environment. According to the structure and property of biofilm, a natural biopolymeric gel, calcium alginate(an extracellular biopolymer containing carboxylate functional groups) can deposite on metal surfaces to form films. Corrosion behavior of alloyed steel E2, 10CrMoAl and 18-8 stainless steel were studied in simulated biofilm environment by various electrochemical methods ,including measurements of the corrosion potential, polarization curves,galvanic current and electrochemical impedance. The results show that such an approach is informative to reveal “how” and “to what extent” biofilm can influence the metal corrosion process.

Calculation Of The Sacrificial Anode Resistance Utilizing Boundary Element Method, Jianhua Wu, Mingxian Sun, Guangzhou Liu, Guangzhang Chen

Journal of Electrochemistry

According to a kind of mathematic model set up for the cathodic protection potential field, the boundary element method (BEM) was used to study the working state of plate sacrificial anodes which were galvanically coupled to mild steel. In situ experiment showed that the current output and resistance of sacrificial anodes could be calculated more accurately using BEM than loiyd formula. On the basis of the calculation, the cathodic protection design would be more accurate. It was also investigated that the effect of the length to breadth ratio (L/B) on current output and resistance of plate zinc anodes. The results …

Corrosion Behaviour Of Copper Covered With Ion Selective Phenolic Coatings By Eis, Zhoucheng Wang, Yingzhou Zhang, Shaomin Zhou

Journal of Electrochemistry

Electrochemical impedance spectroscopy(EIS) technique was employed to study the corrosion behaviour of copper painted with the anion selective, cation selective and bipolar phenolic coatings in 3% NaCl solution. From the impedance spectrum characteristics, the models of equivalent circuit for these different coating systems were established, and the methods for the analysis of experimental impedance diagrams in terms of coating and interface properties were discussed. The research results show that the composition and structure of ion selective coatings have significant influence on corrosion behaviour of copper. The bipolar coating consisting of an anion selective inner layer and a cation selective outer …

Computer Modeling Of Molecular Vibration Frequencies And Its Application To The Modeling Of Silane Compounds, Ryan T. Merrell

Honors Capstone Projects and Theses

No abstract provided.

Growth Kinetics And Breakdown Of Passive Films On Rebar Electrodes In Simulated Cement Pore Solution, Wei Chu, Yuanxiang Shi, Baoming Wei, Yong Yang, Xuguang Chen, Zugeng Lin

Journal of Electrochemistry

The growth kinetics and breakdown of passive films on REBAR electrodes insimulated cement solution (pH=12.5 and 13.8) have been investigated using in situ photoelectrochemical methods and potential step method. The results show that there are two mainstages in the growth of the film, with two rate functions characterized by linear relation between thefilm thickness and the direct logarithm of time. There is a sign in laser-scanning photoelectrochemical microscopic image just before the passive film breaks down. The addition of inhibitor NaNO₂ changes the growth kinetics and thickness of the film, and therefore improves the resistance of pitting corrosion induced …

The Photoelectrochemical Studies Of Passive Films On Rebar Electrodes In Simulated Cement Pore Solution, Wei Chu, Yuanxiang Shi, Baoming Wei, Yong Yang, Xuguang Chen, Zugeng Lin

Journal of Electrochemistry

The electronic properties of the passive film on REBAR electrodes in simulatedcement pore solution (pH=9.0～13.8) have been investigated using in-situ photoelectrochemical methods. The results show that the passive film is composed of mixed oxides of ferrum, and it is an amorphous, n-type semiconductive film. Variations of pH values, ions in the solution and film-formation potentials can affect the composition of the films. There are two main stages in the growthof the film, with two rate functions characterized by linear relation between the film thickness and thelogarithm of time. The addition of inhibitor NaNO₂ changes the composition, structure and growth …