Engineering Science and Materials Commons^™

Inexpensive Fluid Flow Visualization In A Microfluidic Channel Experiment Overview, Maoling Chu

Bridges: A Journal of Student Research

Flow visualization is vital to describe the motion of a fluid in microfluidic channels. This paper summarizes and lists systems based on two common visualization technique categories: particle-based techniques and scalar-based techniques. For this experiment, microfluidic channels were created using PDMS (polydimethylsiloxane). Based on our results and many fabrication trials, it was difficult to say whether this experiment was easy or inexpensive. If the first channel made by the researchers had successfully worked, it would have been clear that utilizing PDMS to fabricate a microfluidic channel for flow visualization was cheap and easy. However, no fully successful microfluidic chips were …

Using Mechanics Of A Double Pendulum To Maximize Sport Performance, Heston Neal

Bridges: A Journal of Student Research

Sports have developed over time into an entire industry from the children who grow up playing sports to the professional players that fans love to watch. Because all sports involve movements of the human body, a bio-mechanical system, these movements may be modeled with mathematics and physics. Specifically, the sports of golf, tennis, and baseball can use the concepts of a double pendulum to maximize sport performance. The double pendulum model is applied to these sports by making the arm one pendulum and the club, racquet, or bat the second pendulum. A good understanding of the mechanics of a double …

Attainment Of Rigorous Thermodynamic Consistency And Surface Tension In Single-Component Pseudopotential Lattice Boltzmann Models Via A Customized Equation Of State, Cheng Peng, Luis F. Ayala, Zhicheng Wang, Orlando M. Ayala

Engineering Technology Faculty Publications

The lack of thermodynamic consistency is a well-recognized problem in the single-component pseudopotential lattice Boltzmann models which prevents them from replicating accurate liquid and vapor phase densities; i.e., current models remain unable to exactly match coexisting density values predicted by the associated thermodynamic model. Most of the previous efforts had attempted to solve this problem by introducing tuning parameters, whose determination required empirical trial and error until acceptable thermodynamic consistency was achieved. In this study, we show that the problem can be alternatively solved by properly designing customized equations of state (EOSs) that replace any cubic EOS of choice during …

Development Of Software Tools And Experimental In Situ Electron Spin Resonance For Characterizing The Magnetic And Electrocatalytic Properties Of Transition Metal Chalcogenide Crystals, Jose Armando Delgado

Open Access Theses & Dissertations

Studying the magnetic properties and crystal defects of transition metal chalcogenide crystals is of paramount importance for utilizing them for next generation spintronics devices and hydrogen evolution reaction catalysts. Hydrothermally grown transition metal chalcogenide nanocrystals (MoS2, Ru2S3, Rh2S3, Co2S8) were chosen as catalysts for the hydrogen evolution reaction due to their low dimensionality and previous utilization as catalysts for hydrodesulfurization. The relationship between crystal defect sites and catalytic activity must be discerned to maximize the efficiency of hydrogen production during the hydrogen evolution reaction. ESR spectroscopy was utilized as a spin sensitive technique to study the defects and local changes …

Ideal Lacrosse Stick, Josh Beck, Tyler Skoloda, Noah Reed, Stanley Dembosky

Williams Honors College, Honors Research Projects

This project is focused on the design of a new and innovative lacrosse stick. Our main points of focus will be the strength and durability of the head. As well as solving some of the problems that exist in existing equipment. These problems were identified by interviewing experienced players at the college level. Benefits would include a stronger head that is easier to use for a player on the field to do things like pass, catch, shoot, and field ground balls in an optimal manner. Normally players will have to purchase new heads every season as a result of warping …

Investigation Of Iron Doped Gallium Oxide (Ga-Fe-O) System: Structure Property Relationship And Performance Evaluation For Optical And Catalytic Applications, Swadipta Roy

Open Access Theses & Dissertations

From September 2012 to May 2015, a phenocam monitored the seaward edge of a protected mangrove forest. Calculated GCC revealed seasonal greening patterns of a mangrove species, Rhizophoa apiculata, and an overall increase in the GCC, suggesting mangrove expansion. In comparing temperature and precipitation effects, it was found that this particular mangrove species had a greening optima at temperatures between 28°C and 28.5°C, and greening and canopy development response lag time of 10 weeks in response to precipitation. Tree saplings were monitored and showed to grow by 50%, mostly during a three month period during the rainy season. The establishment …

Superconductivity In La₂Ni₂In, Jannis Maiwald, Igor I. Mazin, Alex Gurevich, Meigan Aronson

Physics Faculty Publications

We report here the properties of single crystals of La₂Ni₂In. Electrical resistivity and specific heat measurements concur with the results of density functional theory calculations, finding that La₂Ni₂In is a weakly correlated metal, where the Ni magnetism is almost completely quenched, leaving only a weak Stoner enhancement of the density of states. Superconductivity is observed at temperatures below 0.9 K. A detailed analysis of the field and temperature dependencies of the resistivity, magnetic susceptibility, and specific heat at the lowest temperatures reveals that La₂Ni₂In is a dirty type-II …

Synthesis Of Graphene Using Plasma Etching And Atmospheric Pressure Annealing: Process And Sensor Development, Andrew Robert Graves

Graduate Theses, Dissertations, and Problem Reports (ETD)

Having been theorized in 1947, it was not until 2004 that graphene was first isolated. In the years since its isolation, graphene has been the subject of intense, world-wide study due to its incredibly diverse array of useful properties. Even though many billions of dollars have been spent on its development, graphene has yet to break out of the laboratory and penetrate mainstream industrial applications markets. This is because graphene faces a ‘grand challenge.’ Simply put, there is currently no method of manufacturing high-quality graphene on the industrial scale. This grand challenge looms particularly large for electronic applications where the …

The Potentials Of Faecal Sludge Treatment Using Local Conditioners In Tanzania: A Review, Doglas Benjamin1

Tanzania Journal of Engineering and Technology (TJET)

Worldwide, every day human beings generate millions of tons of Faecal Sludge (FS), which is rich in water, nutrients, energy, and organic compounds. Yet FS is not being managed in a way that permits us to derive value from its reuse, while at the same time, millions of farmers struggle with depleted soils and lack of water. In most of the developing countries, energy for cooking is mainly derived from cutting of trees, either as wood or charcoal. Resource recovery and reuse from FS can create livelihoods, enhance food security, support green economies, reduce waste and contribute to cost recovery …

Morphology Controlled Preparations And Electrochemical Properties Of Znco2O4 Electrode Materials For Supercapacitors, Yue-Shen Zhou, Meng Li, Shuang Wu, Zhao-Lei Li, Yan-Min Gao

Journal of Electrochemistry

In this work, hydrothermal reaction and high temperature were used to grow ZnCo₂O₄ active materials on Ni foam. The crystal stuctures and surface morphlogies of four samples were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The electrochemical performances were characterized by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) testing and electrochemical impedance spectroscopy (EIS) on an electrochemical station. It can be seen that active materials tended to form denser stuctures with an increasing amount of NH₄F in the solution system and four different morphologies of ZnCo_{2 …}

Electrochemical Behaviors Of Azopurine On Gold Electrodes, Ming-Xue Li, Hang Shi, Jia Liu, Meng Zhang, Jian-Zhang Zhou, De-Yin Wu, Zhong-Qun Tian

Journal of Electrochemistry

In this paper, we studied the electrochemical behaviors of azopurine on polished gold electrodes with cyclic voltammetry (CV). On the basis of analyzing scan rate and peak current, it was supposed that the redox process belonged to a reversible process controlled by adsorption in 0.2 mol·L^-1 PBS (pH = 4.0 ~ 10.0) solutions. The potentials of redox peaks moved more negatively with increasing pH value. This proved that the H⁺ proton has participcted in the electrochemical reaction. The further data analysis and the calculation of surface adsorption excess demonstrated that the reaction was a two-proton and two-electron process. …

Polyaniline Coated Hollow Sulfur Prepared Using Sublimate 2,4,6-Tri(Propan-2-Yl)-1,3,5-Trioxane As Template For Sulfur Electrode, Zhang-Feng Li, Xiao-Rui Wang, Wen-Sheng Tian, Jin-Ze Yang, Ping Zhang, Li-Ping Ma, Yang Chen, Xiao-Li Cui, Zhi-Yu Jiang

Journal of Electrochemistry

An advance method for preparing polyaniline-coated hollow sulfur material using sublimate material ADD(2,4,6-tri(propan-2-yl)-1,3,5-trioxane) as a template was developed for lithium-sulfur battery. At first, the smashed ADD particles were coated by a sulfur layer through the reaction of Na₂S₂O₃ with diluted HCl. Then polyaniline layer was coated again on the surface of sulfur layer through the reaction of aniline with (NH₄)₂S₂O₈. After being dried at 60 ^oC for 12 h, the ADD in such a composite evaporated totally, and resulted in the formation of polyaniline-coated hollow sulfur …

Study On Electro-Sorption Of Heavy Metals And Sulfamethoxazole On Activated Carbon Fibers, Wen-Jun Zhao, Bing-Xin Jia, Ya-Nan Zhang, Jiu-Nian Guan, Jiao Qu, Ying Lu

Journal of Electrochemistry

To study the optimal removal condition, adsorption mechanism and comparative analysis of the three typical cationic pollutants, i.e., Zn(II), anionic pollutant Cr(VI) and molecular pollutant sulfamethoxazole (SMX), using self-made upflowed electro-sorption device for adsorptions of above three pollutants by modified activated carbon fiber were researched. The activated carbon fiber (ACF) was modified by hydrochloric acid. The ACF morphology and structure before and after modification were characterized by SEM, BET and FTIR. The characterization results show that the modified ACF had fewer surface impurities than the modified surface and the gully is more obvious, the specific surface area was increased by …

Transient Electrochemical Surface-Enhanced Raman Spectroscopic Study In Electrochemical Reduction Of P-Nitrothiophenol, Yun Ling, Jing Tang, Guo-Kun Liu, Cheng Zong

Journal of Electrochemistry

P-nitrothiophenol (PNTP) is one of the most common probe molecules studied by surface-enhanced Raman spectroscopy (SERS). The research in electrochemical reduction behavior of PNTP will help understanding the mechanism for the nitrobenzene reduction. In this paper, we used transient electrochemical surface-enhanced Raman spectroscopy (TEC-SERS) to study the SERS of PNTP with cyclic voltammetry and chronoamperometry on gold electrodes. The results show that the TEC-SERS provide a time resolution that equals the transient electrochemical methods, and we concluded that the reaction was so quick that we did not observe the spectral information of intermediate species described in the literatures with a …

Electrochemical Properties Of Sulfur In Different Carbon Support Materials, Bo Zhang, Jia Liu, Xiao-Chen Liu, De-Jun Li

Journal of Electrochemistry

In order to investigate the effect of carbon structure on electrochemical performance of sulfur/carbon composite in lithium-sulfur battery, in this paper, sublimation sulfur was incorporated into three types of carbon materials, namely, graphene, carbon black and porous carbon. The three sulfur/carbon composites were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), and X-ray diffraction (XRD) techniques, and their electrochemical performances were also studied. The results showed that the sulfur/porous carbon composite offered an initial discharge capacity of 1623.2 mA·h·g^-1 and remained 845 mA·h·g^-1 after 100 cycles. Compared with graphene and carbon black, the mesopores and micropores in porous …

Electrochemical Sensor Based On Magnetic Electrode Modified With Magnetic Molecularly Imprinted Nanoparticles Immobilized Hemoglobin For Determination Of Hydrogen Peroxide, Yang Yuan, Jia-Xin Wang, Yu-Hua Cao

Journal of Electrochemistry

In this work, the surface-imprinted technique was used to prepare magnetic hemoglobin (Hb) imprinted nanoparticles, using Fe₃O₄@SiO₂ NPs as the carrier, Hb as the template molecule, and tetraethyl orthosilicate (TEOS) as the imprinted polymer monomer. The nanoparticles had a core-shell structure, with magnetic Fe₃O₄ NPs as the core and Hb imprinted polymers as the shell. Therefore, Hb could be concentrated and fixed on the surface of the magnetic imprinted nanoparticles (MMIPs NPs). Furthermore, MMIPs NPs were immobilized with chitosan (CS) on the surface of a magnetic electrode to constitute Hb enzyme-like biosensor …

Zif-67-Derived Ag/Co-Embedded N-Enriched Mesoporous Carbon For Oxygen Reduction Reaction, Zheng-Ling Di, Jing Zhu, Lei Dai, Wei Meng, Yue-Hua Li, Zhang-Xing He, Ling Wang

Journal of Electrochemistry

Nitrogen-doped porous carbon materials are considered as one of the most promising catalysts for oxygen reduction reaction (ORR). Herein, in order to further improve the activity of the nitrogen-doped porous carbon, Ag/Co bimetal is embedded into nitrogendoped porous carbon to form Ag/Co-embedded nitrogen-doped porous carbon material (AgCo@NC). The AgCo@NC was derived by the wet impregnation of Ag+ into ZIF-67 precursor, followed by chemical reduction and a subsequent pyrolysis process under Ar atmosphere at different temperatures (500 ℃, 600 ℃, 700 ℃). The morphologic characterization shows that the Ag/Co nanoparticles were successfully embedded in the mesoporous carbon framework with abundant nitrogen …

Quantitative Detection Of Levofloxacin Hydrochloride By Differential Pulse Stripping Voltammetry With Electrodeposited Bismuth Film Electrodes, Zi-Ying Guo, Zuo-Peng Li, Jiang Li, Jian-Guo Zhao, Feng Feng

Journal of Electrochemistry

In this study, differential pulse stripping voltammetry was developed for the quantitative detection of levofloxacin hydrochloride indirectly. Levofloxacin hydrochloride contains organic amine, which can be precipitated upon interaction with Zn(SCN)₄^2-. By means of differential pulse stripping voltammetry, the concentration of Zn²⁺ can be determined using an in-situ formed bismuth film electrode, which allows determining indirectly the amount of levofloxacine hydrochloride. The linearity equation, I = 1.1401c - 0.5309 with the correlative coefficient R = 0.9979, was presented in the experiment. The results showed that this approach is very sensitive, having a limitation of detection of 3.18 …

Ionic Liquid Assisted Synthesis Of Porous Carbons From Rice Husk For Supercapacitors, Han-Fang Zhang, Feng Wei, Jian Sun, Meng-Ying Jing, Xiao-Jun He

Journal of Electrochemistry

It is still a challenge to prepare carbon materials with high specific surface area at low cost from renewable resources. Herein, the authors report an efficient approach to synthesize porous carbons (PCs) from rice husk with ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF₆)) as a template and an activation agent. The as-made PCs featured the high specific surface area up to 1438 m²·g^-1. As electrodes for supercapacitors, PCs showed a high specific capacitance of 256 F·g^-1 at 0.05 A·g^-1 in 6 mol·L^-1 KOH aqueous electrolyte and a good rate performance of 211 F·g …

Bipolar-Membrane Electrodialysis Method To Treat Industrial High Saline Perfume Wastewater, Jian Zhang, Dong-Fang Niu, Shuo-Zhen Hu, Xin-Sheng Zhang

Journal of Electrochemistry

Large amount of organic saline wastewater is generated from various chemical industries. The contents of organic saline wastewater are more and more complicated as they are created from different types of industries. Directly discharging the organic saline wastewater without pre-treatment can generate severe environmental problem and waste useful resources. It is necessary to use an economical method to treat the organic saline wastewater and recover the salt into useful materials to achieve resource reuse. Bipolar-membrane electrodialysis (BMED) is one of the methods that can remove salt from the wastewater and convert it into certain acid and base with higher value …

Pressure Driven Electronic Band Gap Engineering In Tin(Iv)-O,N Compounds, Daniel Thomas Sneed

UNLV Theses, Dissertations, Professional Papers, and Capstones

The intrinsic link between long-range order, coordination geometry, and the electronic properties of a system must be understood in order to tailor function-specific materials. Although material properties are typically tailored using chemical dopants, such methods can cause irreversible changes to the structure, limiting the range of functionality. The application of high pressure may provide an alternative “clean” method to tune the electronic properties of semiconducting materials by tailoring their defect density and structure.

We have explored a number of optoelectronic relevant materials with promising characteristics, specifically Sn-(O,N) compounds which have been predicted to undergo pressure-mediated opening of their optical band …

Three-Dimensional Porous Vn Octahedron Catalyst With High Electrocatalytic Efficiency Toward Hydrogen Evolution Reaction, Can Yin, Wei-Wei Fu, Ling Fang, Shi-Li You, Hui-Juan Zhang, Yu Wang

Journal of Electrochemistry

With the rapid development of China’s economy, the demand for energy is increasing, and environmental problems are becoming more and more serious. The development and utilization of highly-clean new energy fuel can effectively alleviate the energy crisis and environmental pollution. Nowadays, exploring high-efficiency, environment-friendly and low-cost catalysts remains the focus of research in the hydrogen evolution reaction (HER). In this research, firstly, we proposed a three-dimensional porous vanadium nitride (VN) with octahedral structure, which was prepared by a calcination treatment method. The VN catalyst showed a good electrocatalytic activity toward HER, involving a small overpotential of 94.0 mV at -10 …

Influences Of Morphology And Nitrogen Doping On The Electrocatalytic Characteristics For Oxygen Reduction Reaction Of Nio/Rgo, Dong Liang, Heng-Yi Fang, Shuo Yao, Jie-Mei Yu, Zhao-Liang Zhang, Zhan-Kun Jiang, Xue-Ping Gao, Tai-Zhong Huang

Journal of Electrochemistry

In this research, the reduced graphene oxide (rGO) supported sheet-like NiO (NiO/rGO) and spherical-like NiO (NiO/N-rGO) catalysts for oxygen reduction reaction (ORR) were prepared. The structures, morphologies and chemical states of the two catalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical catalytic performance of the two catalysts for ORR were investigated by cyclic voltammetry (CV), Tafel, linear sweeping voltammetry (LSV), rotating disc electrode (RDE) and rotating ring disc electrode (RRDE) tests. Electrochemical results showed that the current density and onset potential (about 0.89 V) …

Preparation Of Nanostructural Mno-Porous Graphene Hybrid Material By Thermally-Driven Etching Of Mno For Lithium-Air Batteries, Juan Yang, Jun-Wei Lang, Peng Zhang, Bao Liu

Journal of Electrochemistry

In this paper, improving the surface morphology of graphene(GNSs) as designed concept. we describe a MnO/porous-graphene(MnO-PGNSs) was synthesized by a simple site-localized Mn²⁺ on GO (Mn-GO) by charge adsorption and then driving by high-temperature calcination, growing MnO nanoparticles and etching GNSs achieved on step. And Then focus on the key factors of influenced the etch hole formation are analyzed, founded the dispersion of Mn-GO; layer number of GO and calcination temperature also affected the formation of holes. In addition, the MnO-PGNSs as lithium-air battery cathode exhibits high reversible capacity compared with GNSs and PGNs and it is able to …

Special Issue: Electrocatalysis And Fuel Cells, Shuangyin Wang

Journal of Electrochemistry

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A Facile Route To Synthesize Pt-Wo3 Nanosheets With Enhanced Electrochemical Performance For Her, Peng-Jie Jiang, Yi Lv, Chang-Miao Chen, Hong-Cheng He, Yong Cai, Ming Zhang

Journal of Electrochemistry

Platinum-tungsten trioxide (Pt-WO₃) nanosheets were synthesized on nickel foams (NFs) directly. As great conductive networks, NFs substrates could greatly improve the electrode performance of WO₃. The modified platinum nanoparticles not only enhanced the electron transformation of catalysts, but also increased the active sites for hydrogen evolution reaction (HER). Pt-WO₃/NF revealed a better catalytic activity than WO₃/NFs with a smaller Tafel slope (80 mV·dec^-1) and a lower overpotential of 72 mV at the current density of 10 mA·cm^-2. In addition, Pt-WO₃/NF showed great durability and stability during …

Nickel Selenide Derived From [Ni(En)3](Seo3) Complex For Efficient Electrocatalytic Overall Water Splitting, Dan-Dan Chen, Xue-Qing Gao, Hong-Fei Liu, Wei Zhang, Rui Cao

Journal of Electrochemistry

Electrocatalytic water splitting is considered as a promising technology for renewable energy. The development of efficient, stable, cost-effective, and bifunctional catalysts for both water reduction and oxidation has continued to face significant challenges. Herein, we report a robust and highly active nickel selenide (NiSe) spheres grown on carbon cloth (CC) by electrodeposition from a nickel selenite complex which is a single source containing both Ni and Se. A combination of two chemicals containing, separately, Ni and Se is used in traditional preparations of metal selenides, causing possible problems in the uniformity of the products. The as-prepared NiSe-EA/CC electrode exhibited electrocatalytic …

Pd Nanoparticles Supported On The Etched Ni Foams As High-Performance Electrocatalysts For Direct Ethanol Fuel Cells, Chi Zhang, Cheng-Fei Li, Gao-Ren Li

Journal of Electrochemistry

The development of non-Pt anode electrocatalysts with high activity and long-term durability at low cost for fuel cells still remains enormous challenge. Here we report the Pd nanoparticles supported on Ni foams etched by the mixed acids (HNO₃+H₂SO₄+H₃PO₄+CH₃COOH) (Pd/ME-NF) that are designed and fabricated as high-performance electrocatalysts for ethanol oxidation in alkaline media. Because of the advantages of large open space, fast electrolyte penetration/diffusion and rapid electron transfer process, the Pd/ME-NF catalysts exhibited significantly improved electrocatalytic activity and durability compared with the commercial Pd/C catalysts.

Investigations In Electrochemical Thermodynamic And Kinetic Properties Of As-Cast And As-Quenched Cemg10Ni2 Hydrogen Storage Alloys, Feng Hu, Li-Rong Luo, Yong-Zhi Li, Ting-Ting Zhai, Xin Zhao, Yang-Huan Zhang

Journal of Electrochemistry

In order to improve the electrochemical hydrogen storage properties of CeMg₁₀Ni₂ alloy, the rapid quenching technology was used to prepare CeMg₁₀Ni₂ alloys with nano-crystalline and amorphous structure. The microstructures of as-cast and as-spinning sample were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical hydrogen storage properties were investigated by an automatic galvanostatic charging/discharging, high rate discharging (HRD), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The results revealed that the as-cast alloy was composed of multiphase structures. The as-quenched alloys were made up of nano-crystalline and/or amorphous structures, and the …

On The Pulsed Laser Ablation Of Metals And Semiconductors, Todd A. Van Woerkom

Theses and Dissertations

This dissertation covers pulsed laser ablation of Al, Si, Ti, Ge, and InSb, with pulse durations from tens of picosecond to hundreds of microseconds, fluences from ones of J/cm² to over 10,000 J/cm², and in ambient air and vacuum. A set of non-dimensional scaling factors was created to interpret the data relative to the laser and material parameters, and it was found that pulse durations shorter than a critical timescale formed craters much larger than the thermal diffusion length, and longer pulse durations created holes much shallower than the thermal diffusion length. Low transverse order Gaussian beams …