Chemistry Commons^™

The Accelerated Test Of Simulated Atmospheric Corrosion And The Rust Evolution Of Low Carbon Steel, Jun-Hua Dong, Wei Ke

Journal of Electrochemistry

It has been set up an accelerated method of simulating to atmospheric corrosion by using wet/dry alternate test.The rust evolution rule of mass change vs time(in logarithmic coordinate) of low carbon steel under this test shows two linear sections with different slopes,in which the rust evolution transition in weight change corresponds to the compactness transition and crystallization transition during the rust layer growth.It has found that the rust evolution rule of low carbon steel in Wanning exposure site correlates to the rust evolution rule obtained by simulating the coastal atmospheric corrosion test,and the rust evolution rule of low carbon steel …

Investigation Of Electrochemical Noise In The Crevice Corrosion Of Q235 Carbon Cteel, Qian Hu, Yu-Bing Qiu, Xing-Peng Guo

Journal of Electrochemistry

The crevice corrosion behavior of Q235 carbon steels in a NaHCO₃+NaCl solution was investigated by electrochemical noise(EN) and electrochemical impedance spectroscopy(EIS).Three stages of crevice corrosion including the induction,the rapid transform and the stable development could be clearly distinguished.The characteristics of the electrochemical noise and the noise resistance Rn showed remarkable differences at each stage.The electrode area ratio(r) of outside to inside the crevice had a significant influence in the development of crevice corrosion.The time of the induction stage increased with increasing r.However,under the stable development stage of the crevice corrosion,the surface outside the crevice was at an active …

Effect Of Naphthalene Water Reducer On Corrosion Behavior Of Reinforcing Steel In Concrete, Yu-Ming Tang, Jie Zhang, Yu Zuo

Journal of Electrochemistry

The influence of naphthalene water reducer on corrosion behavior of reinforcing steel in concrete was studied by the methods of corrosion potential measurement,linear polarization and EIS test.The values of concrete resistance(Rc) and polarization resistance(Rp) of the samples with naphthalene water reducer were higher than those without naphthalene water reducer,especially in the concrete with 0.2 percent naphthalene water reducer.A suitable amount of water reducer can improve the pore structures of concrete,increase the concrete compactness and impermeability,and decrease corrosion rate of rebars in concrete.

Effect Of Electrochemical Property Of Uns J91450 Stainless Steel On Stress Corrosion Cracking In Hydrogen Sulfide Solutions, Zhi-Yong Liu, Chao-Fang Dong, Xiao-Gang Li, Li-Xian Wang

Journal of Electrochemistry

Effect of electrochemical behaviours on stress corrosion cracking(SCC) of UNS J91450 stainless steel in hydrogen sulfide environment was investigated using slow-strain-rate test(SSRT) and electchemial techniques.Results show that UNS J91540 stainless steel was susceptible to SCC in varying H₂S solutions,and the SCC susceptibility reduced with the increase of pH value.The electrochemical property plays an important role in the SCC occurrence,as a combined effect of hydrogen embritlement and anodic dissolution at SCC cracktip at open circuit potential.In the solution with a lower pH the hydrogen revolution was intensive and the cracktip anodic dissolution was weaker,however,in the higher pH solution the …

Developments Of Scanning Electrochemical Probes And Their Applications In Studying Of Localized Corrosions, Chang-Jian Lin, Yan Li, Bin Lin, Rong-Gang Hu, Min Zhang, Xiang-Dong Zhuo, Rong-Gui Du

Journal of Electrochemistry

The electrochemical inhomogeneities always exist at the interface of metal/solution,and play an important and often controlling role in localized corrosion of metals in a given environment.It is necessary to develop in situ imaging techniques for further studying the electrochemical and environmental inhomogeneities at the interface of metal/solution for the localized corrosion system.In this paper,various techniques with spatial resolution,such as scanning micro reference electrode(SMET),scanning electrochemical microscope(SECM),atomic force microscope(AFM),and scanning Kelvin probe(SKP),and their applications in corrosion studies were briefly reviewed.The chemical probes and array electrode have been developed.It was concentrated to describe our newly developed techniques of the scanning electrochemical probes,including SMET …

Preparation And Electrochemical Properties Of Layered Manganese Oxide(Li-Birnessite Type), Xing-Kang Huang, Hai-Tao Chang, Jian-Long Gan, Qing-Shun Zhang, Hong-Jun Yue, Dong-Ping Lv, Yong Yang

Journal of Electrochemistry

Layered Li-birnessite was prepared by means of oxidizing Mn²⁺ with O₂ gas in alkaline media.The as-prepared sample was characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD), BET and thermogravimetric/diffenential thermal analysis(TG/DTA) techniques. The electrochemical properties of the material were also investigated. The results show that such a Li-birnessite consists of well-crystallized spherical particles with an interlayer distance of 0.70 nm. The Li-birnessite delivered a high discharge capacity of 203 mAh/g at a rate of 0.2 C(40 mA/g), and had good rate capability as well.

Electrochemical Behavior Of Mg-Li Electrodes In Nacl Solution, Lin Wu, Yan-Zhuo Lv, Xue Cao, Gui-Ling Wang, Dian-Xue Cao

Journal of Electrochemistry

The Mg-Li electrodes containing 8.5% and 14% Li were prepared using an induction melting method. Their electrochemical behavior in NaCl solution was investigated by means of potentiodynamic polarization, potentiostatic oxidation,electrochemical impedance technique and mass-loss measurements. The morphology of the electrodes after discharge was examined using scanning electron microscopy. The Mg-14Li electrode showed more negative open circuit potential and higher discharge current density than Mg-8.5Li electrode. The oxidation products of Mg-14Li loosely attached on the electrode surface and peeled off easily. The Mg-8.5Li exhibited higher utilization efficiency. Both electrodes gave higher utilization efficiencies when discharged at lower anodic potential.

Electrochemical Performance Of The Exfoliated Graphite Containing Sulfur Cathode Material For Lithium Sulfur Battery, Ke-Guo Yuan, Wei-Kun Wang, Zhong-Bao Yu, An-Bang Wang

Journal of Electrochemistry

The exfoliated graphite containing sulfur cathode material was prepared by the high temperature sulfur gas diffusion adsorption method.This cathode material could obtain an initial discharge specific capacity 972 mAh·g^-1,capacity retention ratio 78% and cycling efficiency above 80%,respectively.The exfoliated graphite containing sulfur cathode could decrease the reaction interphase charge transfer impedance,and restrain the sulfur or polysulfide shuttle phenomenon during the charge-discharge process through improving the diffusion impedance.

Effects Of Kscn On Kinetic Characters Of The Positive Couple And Performance For Vanadium Redox Flow Battery, Jian-Guo Liu, Dong Shi, Yue Men, Chuan-Wei Yan

Journal of Electrochemistry

In order to improve the reaction activity of VO²⁺/VO²⁺ and the battery performance of Vanadium redox flow battery,different concentration of potassium sulfocyanates KSCN were added into 0.1mol/L VOSO₄/ H₂SO₄ solution,and the kinetic characters of electrochemical reaction of VO²⁺/VO²⁺ was studied by CV and EIS.The results showed that the addition of KSCN could improve the oxidative peak current value of positive couple VO²⁺/VO²⁺ reaction,but had little influence in the reductive peak.The addition of KSCN decreased the impedance at 1.0 V.And the value of standard rate constant k0 …

Effect Of Impurity Cu(2+) On Oxygen Electrode In Pemfc, Xiao Jie, Jun-Bo Hou, Zhi-Gang Shao, Bao-Lian Yi

Journal of Electrochemistry

Rotating disk electrode was adopted in this paper to simulate the cathode in PEMFC.In the Cu²⁺ electrolyte,the influence of impurity Cu²⁺ on Carbon-Supported Pt Catalysts was investigated by using electrochemical measurements such as chronocoulometry,cyclic voltammetry and linear sweep.Experimental results showed that,after constant voltage at 0.49 V,the ECA of Pt/C decreased dramatically,it's perhaps under potential deposition of Cu might occur on the substrate.Meanwhile the change of ORR Tafel scope reaction is very large.It might be because oxygen adsorption sites are occupied by Cu atoms after they under potential deposit on surface of Pt/C catalyst,and the adsorption of oxygen on …

Electro-Oxidation Of Methanol On Fe-Doped Pt-Zro2/C Catalyst, Mao-Cai Lin, Dong-Dong Liu, Qing-Chun Yu, Ming-Ruo Hu, Heng-Yong Tu

Journal of Electrochemistry

The Fe-doped ZrO₂ powders were prepared by so-gel method.After that,Pt-Zr_1-xFe_xO₂/C catalysts were made by reducing platinum salts with ethylene glycol.The physical property of the catalyst was characterized by XRD and TEM.It was found that the distribution of the catalyst was narrow,the particle sizes of Pt and ZrO₂ particles were 2~4 nm and 3~7 nm,respectively.The Cyclic Voltammetry and Chronoamperometry testing indicated that the electro-catalytic activity for methanol electro-oxidation on Pt-ZrO₂/C catalyst increased when ZrO₂ was doped with Fe.And Pt-Zr_0.95Fe_0.05O₂/C catalyst showed the highest activity …

Investigation On Electrogenerated Active Chlorine From Diluted Nacl Solutions At Ti/Pt Anode, Hao Shen, Jin-Hong Fan, Lu-Ming Ma

Journal of Electrochemistry

Electrogeneration of active chlorine from diluted NaCl solutions was investigated in an undivided cell with Ti/Pt anode and Ti plate cathode.The effects of electrolysis time,current density(i),chloride concentration and pH value on the electrogeneration of active chlorine and current efficiency(CE) were analyzed.Meanwhile,the changing trends of the electrolyte's conductivity(TSD) and pH value in the electrolysis process were discussed.The results showed that the concentration of active chlorine increased with electrolysis time,but the trend became slow.During this process,the current efficiency reduced steadily.When i was 4.93～7.39 mA/cm²,the concentration of active chlorine increased with the increase of i,but no longer increased when the i …

Influence Of Nano-Al2O3 Particles In Nickel Electro-Crystallization Process, Cheng-Yu Tan, Wei Hu, Hang Cui, Yu Liu

Journal of Electrochemistry

The influence of nano-Al₂O₃ particles in nickel electro-deposition on copper matrix from acid sulphate solution was studied under various potentials by using cyclic voltammetry(CV) and chronoamperometry(CA).The results show that the beginning potential of electro-deposition was about-740 mV(vs.SCE) for Ni-Al₂O₃ solution system.With the step-potential moving to the negative direction,the nucleation time of electro-deposition for Ni-Al₂O₃ solution system was shortened gradually.Compared with that of pure Ni deposition system,the nucleation time tm,corresponding to the peak current of Ni-Al₂O₃ deposition system was apparently shortened under the lower step-potential:-740~-830 mV,which indicates that Al …

Genetic Analysis Of Ribosome Stalling And Rescue, Douglas Ray Tanner

Theses and Dissertations

In eubacteria, ribosome stalling on broken messenger RNA transcripts can lead to cell death. The trans-translation quality control mechanism rescues many of these stalled ribosomes. In this process, tmRNA enters stalled ribosomes by mimicking a transfer RNA, accepting the stalled nascent peptide. The ribosome then releases the broken mRNA and resumes translation on a coding region within tmRNA itself. Translation of tmRNA marks the nascent peptide for destruction by the addition of a short proteolysis tag and the ribosome is released at a stop codon within the tmRNA open reading frame. An intriguing aspect of trans-translation is that …

Reductive Decomposition Of A Diazonium Intermediate By Dithiothreitol Affects The Determination Of Nos Turnover Rates, Perera N. Indika, Talal Sabbagh, Jean A. Boutros, Mekki Bayachou

Chemistry Faculty Publications

Accurate determination of nitrite either as such or as the breakdown product of nitric oxide (NO) is critical in a host of enzymatic reactions in various settings addressing structure–function relationships, as well as mechanisms and kinetics of molecular operation of enzymes. The most common way to quantify nitrite, for instance in nitric oxide synthase (NOS) mechanistic investigations, is the spectrophotometric assay based on the Griess reaction through external standard calibration. This assay is based on a two-step diazotization reaction, in which a cationic diazonium derivative of sulfanilamide is formed as intermediate before the final absorbing azo-product. We show that this …

Luminescent Properties Of Ensemble And Individual Erbium-Doped Yttrium Oxide Nanotubes, Yuanbing Mao, Xia Guo, Thai Tran, Kang L. Wang, C. Ken Shih, Jane P. Chang

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

The luminescent properties, including cathodoluminescence and photoluminescence, of the erbium-doped yttrium oxide (Er3+: Y2 O3) nanotubes (NTs) have been systematically studied. These NTs were synthesized by a hydrothermal treatment followed by a dehydration process. Cathodoluminescent measurements show that every Er3+: Y2 O3 NT is luminescent under electron excitation. In the near-infrared region, sharp, well-resolved, pump-power-dependent, and thermally stable photoluminescence was observed from ensemble NTs. Individual NTs also present characteristic luminescent emissions in the same spectral region. These properties make these NTs promising for applications in display, bioanalysis, and telecommunication.

The Use Of Soil Enzyme Activities And Active Carbon As Indicators Of Soil Quality In Response To Management Practices, Tracy Marie Woodruff

Student Theses and Dissertations

In order to meet the increasing needs of food, fiber, and fuel, management practices that enhance the soil health must be sought out. The two studies conducted examined the effects of management practices on soil enzyme activities and active carbon concentration. A forested ecosystem in Oregon was examined following nutrient treatments on forest plots. The effects of tillage, residue management and time on soil enzyme activities and active C were measured in a greenhouse study from the University of Arkansas in Fayetteville, AR, USA. In both studies, β-glucosidase, arylsulfatase, acid phosphatase, and active carbon were analyzed in soil samples. Results …

Microwave Synthesis And Thermal Analysis Of Ru-Dmso Complexes, Shengkuei Chiu

Student Theses and Dissertations

In order to remove sulfur from fossil fuels during the HDS process, RuS2 has been applied for decades. However, the real mechanism for removing sulfur by using RuS2 is vague. The RuS2 model compound studies are in demand to understand the interaction between substrates and catalysts during the HDS process. The model compounds such are thiophene compounds, η1,S-thiophene complexes, π-complexes of benzo- and dibenzothiophenes and Ru-S compounds. Ru-DMSO is a versatile starting reagent for preparing Ru compounds. Compare literature preparation of Ru-DMSO complexes with microwave synthesis, microwave technique improve the preparation of Ru-DMSO compounds. The reaction time was reduced from …

Synthesis And Evaluation Of Stimulatory Properties Of Glycolipids For Natural Killer T Cells, Xiangtian Long

Theses and Dissertations

Natural killer T cells (NKT cells) are a subset of T cells. They regulate a wide range of diseases including infection, tumor growth, and autoimmune diseases, through recognizing glycolipid antigens in the context of CD1d. An understanding of the scope of glycolipid antigens would facilitate use of this cell type in controlling immune responses. Till today, a lysosomal glycolipid, isoglobotrihexosylceramide (iGb3), is the only natural glycolipid that has been found to be recognized by both human and mouse NKT cells. To elucidate the molecular basis of this specific recognition, iGb3 variants were designed and prepared: i) replacement of the C26 …

Investigating Ring Closing Metathesis Product Favorability By Varying The Alkyne Substituent On A Dienyne, Meagan E. Hinze

Undergraduate Honors Thesis Collection

Diene metathesis, which is also known as an olefin metathesis, has been very important for the development of synthetic strategies in organic chemistry since it's inception in the 1950s. The olefin metathesis reaction is when two alkenes exchange the carbons on their double bonds, thus producing two new carbon□arbon double bonds.

Solid Phase Amide Synthesis Using Staudinger-Vilarrasa Coupling And Microwave Irradiation, Ryan Patrick Schmidtz

Undergraduate Honors Thesis Collection

Amide bond formation is an already well documented area of organic chemistry, and is very useful in its application in medicine and pharmaceuticals. However, current methods have not been investigated with regards to optimization of reaction times, solvents, and energy sources. In addition, current methods also utilize toxic solvents to cleave the peptide from the solid phase resin. In our study, we combine the Staudinger and Vilarrasa coupling reactions with microwave irradiation to develop and optimize the synthesis of amide bonds through the use of a solid support. Instead of attaching the peptide to the solid support, our amide bond …

Center Of Ecological Studies Feasibility Project, Suzanne Williams, Jill Leonard

Grant

No abstract provided.

Coexistence And Transition Between Cassie And Wenzel State On Pillared Hydrophobic Surface, Takahiro Koishi, Kenji Yasuoka, Shigenori Fujikawa, Toshikazu Ebisuzaki, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Water droplets on rugged hydrophobic surfaces typically exhibit one of the following two states: (i) the Wenzel state [Wenzel RN (1936) Ind Eng Chem 28:988–994] in which water droplets are in full contact with the rugged surface (referred as the wetted contact) or (ii) the Cassie state [Cassie, ABD, Baxter S (1944) Trans Faraday Soc 40:546–551] in which water droplets are in contact with peaks of the rugged surface as well as the “air pockets” trapped between surface grooves (the composite contact). Here, we show large-scale molecular dynamics simulation of transition between Wenzel state and Cassie state of water droplets …

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 …

Optimization Of A Polydimethylsiloxane Based Passive Sampler Of Common Household Volatile Organic Compounds, Jennifer Lynn Osborne

Undergraduate Honors Thesis Collection

Dangerous volatile organic compounds, or VOCs, can accumulate as indoor air pollution within homes causing health problems in the habitants. In order to determine the concentration of VOCs in such areas a field-deployable sampler is necessary. The focus of this work has been to develop an inexpensive, reusable, sensitive fielddeployable passive sampler for monitoring VOCs in indoor air. We have devised a sampler that uses polydimethylsiloxane (PDMS), which is a common inexpensive, nonpolar adsorbent. The sampler is comprised of an aluminum bottle coated with the PDMS. In operation, the coated portion is exposed to the air to be sampled. The …

Arsenic And Selenium Distribution In Coal-Fired Plant Samples, Pauline Rose Hack Norris

Masters Theses & Specialist Projects

Arsenic and selenium distributions in coal-fired plant samples are studied. This research includes arsenic and selenium concentrations in samples of coal, fly ash, bottom ash, economizer ash, Flue Gas Desulfurization (FGD) slurry and flue gas taken from four power plants with the goal being to examine the distribution of these metals in these materials and calculate a materials balance for the system. All samples were analyzed using ICP-ES.

This research shows that 60-80% of the arsenic in coal-fired plant samples will be associated with the fly ash. Approximately 35-55% of the selenium will be associated with the fly ash and …

Impact Of Flash Animation In Learning Concepts Of Matter Among Elementary Students, Rhodora S. Santos

Theses and Dissertations - UTB/UTPA

This study examines the instructional effect of flash animation on students' achievement in learning specific concepts of matter. The subjects used in this study were 5th-grade students of the researcher from Dan Ramirez Elementary. Each class or section of these students was randomly assigned as the control group (n = 20) and the experimental group (n =20). The subjects in the control group were exposed to traditional textbook reading while the subjects in the experimental group were exposed to flash animation. To measure the students' achievement from the concepts learned, a pre-test and a post test were both administered to …

Multi-Walled Carbon Nanotubes-Modified Polymer Organic Photovoltaics, Tzu-Fan Chen

Masters Theses & Specialist Projects

Since the carbon nanotubes were first discovered by Iijima in 1991, CNTs have been the focus of intense research by many groups. Nearly 7000 papers and 700 theses on carbon nanotubes can be found from the eminent journals such as Nature and Science in the last decade. Since carbon nanotubes show impressive mechanical, physical and electronic properties such as high stiffness, high strength, low density, and excellent thermal conductivity, suggesting its role in light-weight high strength material application. A great quantity of important research has evidently been done in this field. The purpose of this thesis research is to investigate …

Synthesis And Characterization Of Two Metal-Organic Frameworks, Roxanna Schaffino Moore

Theses and Dissertations - UTB/UTPA

Herein, the design and synthesis of two metal-organic frameworks, Zn 4O(FMA)3 (FMA = fumaric acid) and Zn2(CNC) 2(DPT) (CNC = 4-carboxycinnamic acid; DPT = 3,6-Di-4-pyridy1-1,2,4,5-tetrazine) via solvothermal methods are reported. Zn4O(FMA)3 was isolated as light yellow cubic crystals and Zn2(CNC)2(DPT) as light pink-block shaped crystals. The structures of both MOFs were characterized by single X-ray diffraction. Integrity of both MOFs were determined via powder X-ray diffraction and thermal gravimetric analysis. Zn4O(FMA) 3 is an isoreticular MOF exhibiting 6.8 Å pores taking up 5.2 wt % of hydrogen gas at 40 bar and 77K. Zn2(CNC)2(DPT) is a 3D primative cubic net …

Investigation Of Photophysical And Photochemical Processes In Conjugated Polymer Nanoparticles By Single Particle And Ensemble Spectroscopy, Craig Szymanski

All Dissertations

Single molecule imaging has emerged as a powerful tool in a range of applications, but the field is limited by a lack of fluorescent probes with sufficient brightness and photostability for many demanding applications such as tracking of single biomolecules in cells and tissues at video rate with 1 nm spatial resolution. Conjugated polymers hold great promise as a solution to these issues, with a high density of π electrons and variety of chemistries, allowing efficient and tunable absorption of light. This dissertation describes the development and characterization of a novel type of nanoparticle composed of conjugated polymer called CPdots. …