Engineering Commons^™

Oxygen-Exposure Induced Rapid Oxidation Of Spiro-Ometad In Cspbibr2 Perovskite Solar Cells, Wei-Guo Wang, Tian Bai, Gao-Fei Xue, Mei-Dan Ye

Journal of Electrochemistry

2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)-9,9′-spirobifluorene (Spiro-OMeTAD) is the most widely used hole transport material in perovskite solar cells (PSCs). However, its oxidation in the air takes a long time and results in the attack of perovskite by water. In this regard, we performed the oxidation process of Spiro-OMeTAD in oxygen, where perovskite can be protected from water, guaranteeing the integrity of perovskite. It was demonstrated that the champion Spiro-OMeTAD based CsPbIBr₂ PSCs after oxygen oxidation achieved a 7.19% power conversion efficiency (PCE), showing a higher PCE than 6.29% of the champion device oxidized in air. A series of electrochemical characterization methods were applied …

Theoretical Studies Of Metal-N-C For Oxygen Reduction And Hydrogen Evolution Reactions In Acid And Alkaline Solutions, Xue-Ping Qin, Shang-Qian Zhu, Lu-Lu Zhang, Shu-Hui Sun, Min-Hua Shao

Journal of Electrochemistry

Single atom catalysts (SAC) have been regarded as the promising alternatives to platinum group metals due to their low costs and potentially high catalytic activities in various electrocatalytic reactions. The atomic mechanism understanding of activity discrepancy among different metal and nitrogen co-doped carbon-based catalysts is still lacking. Here, non-precious metal and nitrogen co-doped carbons (Me-N-C, Me = Fe and Co) as the model catalysts are investigated by combining experimental and theoretical studies to explore the catalytic activities and corresponding reaction mechanisms toward oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) at universal pHs. Atomic theoretical simulations suggest that Fe-N-C …

Lithium Storage Performance Of Hard Carbons Anode Materials Prepared By Different Precursors, Zhen-Lang Liang, Yao Yang, Hao Li, Li-Ying Liu, Zhi-Cong Shi

Journal of Electrochemistry

Hard carbon is one of the most promising anode material for lithium ion batteries (LIBs) owing to its high stability, widespread availability, low-cost, and excellent performance. The electrochemical properties of hard carbon materials depend strongly on the type of precursors. It is, therefore, very important to choose an excellent hard carbon precursor. Polyacrylonitrile, petroleum pitch and peanut shells were used as raw materials to prepare different hard carbon anode materials for LIBs. These hard carbon anode materials were successfully synthesized in two steps. The selected precursor was firstly carbonized at 600℃ for 1 h in argon atmosphere using heating rate …

Pd-Based Electrocatalysts For Oxygen Reduction And Ethanol Oxidation Reactions: Some Recent Insights Into Structures And Mechanisms, Zhi-Peng Wu, Chuan-Jian Zhong

Journal of Electrochemistry

The development of efficient electrocatalysts for applications in fuel cells, including proton-exchange membrane fuel cell (PEMFC) and direct ethanol fuel cell (DEFC), has attracted extensive research attention in recent years. Oxygen reduction reaction and ethanol oxidation reaction are two of the key reactions where the design of active, stable and low-cost electrocatalysts is critical for the mass commercializations of PEMFCs and DEFCs. This challenge stems largely from the limited understanding of the catalyst structures and reaction mechanisms. Progress has been made in investigations of electrocatalysts derived from Pd-based alloy nanomaterials both experimentally and computationally. We highlight herein some of the …

Preparation And Characterization Of "Water-In-Salt" Polymer Electrolyte For Lithium-Ion Batteries, Xu Hou, Xin He, Jie Li

Journal of Electrochemistry

Since the development of wearable and flexible electronic products, the demand of flexible energy storage devices such as batteries and super capacitors is in urgent. To enhance the safety and cycling stability for flexible lithium-ion batteries, “water-in-salt” polymer electrolyte was prepared by introducing 21 mol·kg^-1 LiTFSI electrolyte into cross-linked polyacrylamide (PAM) after freeze-drying. A great amount of holes with the size range of 10 ~ 20 μm can be found on the surface and in the bulk of polyacrylamide, which is benefited from the freeze-drying process and acts as a great support for the electrolyte uptake. The “water-in-salt” polymer …

Electrochemical Surface-Enhanced Raman Spectroscopic Studies On Nickel Ultramicroelectrode, Li-Wen Wu, Wei Wang, Yi-Fan Huang

Journal of Electrochemistry

Nickel (Ni) electrodes are widely used in electrochemical researches. Understanding electrochemical processes on Ni electrodes through in-situ characterization of adsorbed species on their surfaces is helpful for rational optimization and application of Ni electrochemistry. Microelectrochemical surface-enhanced Raman spectroscopy (μEC-SERS) combines the mass transfer feature of ultramicroelectrode with high-sensitivity characterizations of molecular structures, which is a powerful method for studying Ni electrochemistry on polarization and non-equilibrium conditions. The key point of performing μEC-SERS is to make a SERS-active Ni ultramicroelectrode.
Here, we demonstrate a method of preparing a SERS-active Ni ultramicroelectrode through electrochemical deposition of several atomic layers of …

Detection And Aggregation Of Listeria Monocytogenes Using Polyclonal Antibody Gold-Coated Magnetic Nanoshells Surface-Enhanced Raman Spectroscopy Substrates, Robert T. Busch, Farzia Karim, Yvonne Sun, H. Christopher Fry, Yuzi Liu, Chenglong Zhao, Erick S. Vasquez

Chemical and Materials Engineering Faculty Publications

Magnetic nanoshells with tailored surface chemistry can enhance bacterial detection and separation technologies. This work demonstrated a simple technique to detect, capture, and aggregate bacteria with the aid of end-functionalized polyclonal antibody gold-coated magnetic nanoshells (pAb-Lis-AuMNs) as surface-enhanced Raman spectroscopy (SERS) probes. Listeria monocytogenes were used as the pathogenic bacteria and the pAb-Lis-AuMNs, 300 nm diameter, were used as probes allowing facile magnetic separation and aggregation. An optimized covalent bioconjugation procedure between the magnetic nanoshells and the polyclonal antibody was performed at pH six via a carbodiimide crosslinking reaction. Spectroscopic and morphological characterization techniques confirmed the fabrication of stable pAb-Lis-AuMNs. …

Features Of Chloridizing Roasting Of Almalyk Mining Metallurgical Combinate Wastes, Malokhat Atamuratova, Dildora Khakimboeva, Khasan Sharipov, Zuhra Kadirova, Tulkin Shakarov

CHEMISTRY AND CHEMICAL ENGINEERING

With the aim to develop a comprehensive technology for processing Almalyk Mining Metallurgical Combinate (AMMC) wastes, the influence of chloride additives on the copper and zinc chloride volatilization process is considered. The relationship between presence of the calcium, potassium and sodium chlorides chlorinating additive on the copper and zinc chlorides sublimation from the AGMK wastes at roasting temperatures up to 700-1000˚C was established.

Synthesis Of Superabsorbing Hydrogels Based On Starch Copolymers, Baxodir Kholnazarov, Khayit Turaev, Abdulakhat Jalilov

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of this work is to synthesize highly swellable superabsorbent hydrogels based on starch copolymers. To achieve this goal, mineral-containing superabsorbent hydrogels based on starch, acrylamide, binder and initiator were synthesized. The optimal synthesis conditions were determined and studies were carried out on the influence of the molar ratios of the starting substances on the composition and physicochemical properties of the synthesized superabsorbent hydrogel. In the course of research, the optimum copolymerization temperature was 60 ° C, and the reaction time was 3 hours.

As a result of the study, a superabsorbent hydrogel based on starch, acrylamide and bentonite …

Synthesis Of Thiocol Oligomer Based On Sodium Tetrasulphide, Epichlorhydrine And Ammonium Phosphate, Bakhtiyor Normurodov, Khayit Turaev, Abdulakhat Jalilov, Sherzod Kasimov

CHEMISTRY AND CHEMICAL ENGINEERING

The purpose of this study is the synthesis and study of thiokol oligomer NEP-12 brand based on sodium tetrasulfide, epichlorohydrin and ammonium phosphate, which is intended for use as a main component of Thiokol sealant. To achieve this goal, a thiokol oligomer based on sodium tetrasulfide, epichlorohydrin, and ammonium phosphate was synthesized and investigated, and the optimal conditions for the synthesis of a thiokol oligomer were determined. Research has been carried out on the influence of the molar ratios of the starting substances on the composition and physicochemical properties of the synthesized thiocol oligomer. The optimum polycondensation temperature was taken …

Synthesis And Structure Of The Coordination Complex Of Copper Ion With Collagen, Dildorа Sadikova, Adham Rafikov, Oybek Tursunqulov, Dilnoza Soyibova

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of this work is to synthesize, determine the composition and microstructure of complexes of copper (II) sulfate with collagen for use as a dye for textile material. Coordination complexes of copper (II) sulfate with collagen synthesized at different ratios of the initial substances by the interaction of solutions of different concentrations of copper sulfate and collagen of raw skin. With an increase in the salt content, the yield of the reaction product increases. With an excess of collagen, some of it does not bind into a complex and precipitates. With an excess of salt, almost the weight of …

Synthesis Of Sodium Ammonium Hydrophosphate And Sodium Dihydrophosphate Based On Extraction Phosphoric Acid From Central Kyzylkum Phosphorites, Kamola Arifdjanova, Kholtura Mirzakulov, Sherzod Khujamberdiev, Melikulova Gavkhar

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of the research is the synthesis of sodium ammonium hydrogen phosphate and sodium dihydrogen phosphate based on purified extraction phosphoric acid.

The acid was purified from accompanying impurities by precipitation methods using sodium carbonate and metasilicate, washed burnt phosphoconcentrate, barium carbonate, acid neutralization with gaseous ammonia. Pre-neutralization of the purified solution of monoammonium phosphate with sodium carbonate to the ratio Na₂O:P₂O₅ = 0.44 and subsequent drying at a temperature of 50 °С allows to obtain sodium ammonium hydrogen phosphate tetrahydrate, and at 100 °С sodium dihydrogen phosphate monohydrate.

The individuality and purity of …

Physico-Chemical Properties And Structural Transformations In The Synthesis Of Boroalumosilicate Glass-Crystal Materials, Julia Yeganyan

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of this work is to study the areas of glass formation and metastable liquation of the pseudo-ternary system (MgO·Al₂O₃)-B₂O₃-SiO₂, and study of the crystallization process of glasses of cordierite composition. The crystallization process of glasses of cordierite composition containing B₂O₃ by a single-stage heat treatment at 1000 ^oC and 1200 ^oC, the nature of crystallization, the thermal properties of glasses and glass crystalline materials of the system (MgO·A_l2O₃)-B₂O₃-SiO₂ were studied. It revealed that during …

Simulation Of Optical Properties Of Dielectric Layers From Visible To Near Infrared Spectral Range, Andrew Cochran, Cory Conkel

ONU Student Research Colloquium

Optical properties of dielectrics play a critical role in various applications including the design and manufacture of optical components & devices such as detectors, filters, imagers, lenses, optical coatings, photonic crystals, sensors and waveguides, and solar cells. Radiative properties of varying thicknesses of different dielectrics such as Aluminum Oxide (Al2O3), Silicon Dioxide (SiO2), Indium Tin Oxide (ITO), Magnesium Fluoride (MgF2) and Silicon Nitride (Si3N4) have been simulated and compared in the range of visible to near infrared by mathematical modelling using MATLAB simulations. The results of the evolution of the radiative properties, as a function of dielectric material thickness, on …

Polymers And Solvents Used In Membrane Fabrication: A Review Focusing On Sustainable Membrane Development, Xiaobo Dong, David Lu, Tequila A. L. Harris, Isabel C. Escobar

Chemical and Materials Engineering Faculty Publications

(1) Different methods have been applied to fabricate polymeric membranes with non-solvent induced phase separation (NIPS) being one of the mostly widely used. In NIPS, a solvent or solvent blend is required to dissolve a polymer or polymer blend. N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and other petroleum-derived solvents are commonly used to dissolve some petroleum-based polymers. However, these components may have negative impacts on the environment and human health. Therefore, using greener and less toxic components is of great interest for increasing membrane fabrication sustainability. The chemical structure of membranes is not affected by the use of different solvents, …

An Alternative Approach To Nucleic Acid Memory, George D. Dickinson, Golam Md Mortuza, William Clay, Luca Piantanida, Christopher M. Green, Chad Watson, Eric J. Hayden, Tim Andersen, Wan Kuang, Elton Graugnard, Reza Zadegan, William L. Hughes

Materials Science and Engineering Faculty Publications and Presentations

DNA is a compelling alternative to non-volatile information storage technologies due to its information density, stability, and energy efficiency. Previous studies have used artificially synthesized DNA to store data and automated next-generation sequencing to read it back. Here, we report digital Nucleic Acid Memory (dNAM) for applications that require a limited amount of data to have high information density, redundancy, and copy number. In dNAM, data is encoded by selecting combinations of single-stranded DNA with (1) or without (0) docking-site domains. When self-assembled with scaffold DNA, staple strands form DNA origami breadboards. Information encoded into the breadboards is read by …

Funtionalization Of Morphologically Different Nanoclays For Enhanced Mechanical Properties, Malachi Kent

Honors College Theses

Nanoclays are microscopic clays that are comprised of layered nanoparticle aluminosilicates that are naturally arranged in several morphologies. Halloysite nanotubes (HNT) are hollow, double-layered tubes, bentonite (BNT) clays are trapezoidal platelets, and nanosilica or silica dioxide (SiO₂) are spherical. These nanoclays were chosen for sustainable purposes as they are naturally derived and for economical purposes because of their cheap commercial availability. In this study, the nanoclays are functionalized with an epoxy organosilane group through reflux conditions at 120 °C for 24 hours. The pristine and functionalized nanoclays were extensively characterized with infrared radiation (IR) spectroscopy, scanning electron microscope …

Growth And Characterization Of Molecular Ferroelectric Thin Films, Yifan Yuan

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Compared with inorganic ferroelectrics, organic ferroelectrics have advantages of low cost and low toxicity, are in increasing demand in capacitors, piezoelectric, and memory devices to reduce the environmental load. This work focuses on two types of organic molecular ferroelectric materials, croconic acid (CA) and 2-methylbenzimidazole (MBI). The work here introduces several origins of ferroelectricity in typical organics and their switching mechanism. We then investigated the nucleation, growth, and ferroelectric measurements of CA thin films. We explored the effect of substrate temperature and an external electric field on the nucleation and growth processes. The results can be used to improve the …

Fundamental Dislocation Solutions For Infinite And Semi-Infinite Media, Luo Li Mr

Mechanical Engineering ETDs

Much research has gone into determining stress fields of dislocation, as the understanding of dislocations is fundamental to understanding metal or crystal plasticity. In this thesis, the stress field of a rectangular dislocation loop in an infinite isotropic solid is developed for a Volterra-type dislocation with three non-zero Burgers vector components. Also, the stress and strain fields of a rectangular dislocation loop in an isotropic solid, which is a semi-infinite medium, are obtained here for a Volterra-type dislocation. Moreover, analytical and numerical verifications of the developed stress/strain fields are performed. This is done by ensuring the satisfaction of the equilibrium …

Open Source 3d-Printable Planetary Roller Screw For Food Processing Applications, Marcello C. Guadagno, Jacob M. Loss, Joshua M. Pearce

Michigan Tech Publications, Part 1

Historically, open source agriculture (OSA) was based on grassroots technology generally manufactured by hand tools or with manual machining. The rise of distributed digital manufacturing provides an opportunity for much more rapid lateral scaling of open source appropriate technologies for agriculture. However, the most mature distributed manufacturing area is plastic, which has limited use for many OSA applications. To overcome this limitation with design, this study reports on of a completely 3D-printable planetary roller screw linear actuator. The device is designed as a parametric script-based computer aided design (CAD) package to allow for the easy adaption for a number of …

Sulfate Optimization In The Cement-Slag Blended System Based On Calorimetry And Strength Studies, Mustafa Fincan

USF Tampa Graduate Theses and Dissertations

Optimization of sulfur trioxide (SO³) content is typically conducted for plain cements (OPC-based) paste or mortar systems using compressive strength testing and isothermal calorimetry for quality control. The objective of these procedures is to ensure adequate strength and set properties by controlling the time of occurrence of the aluminate peak by adjusting the SO³ content by incremental addition of sulfate in the form of hemihydrate at three or more levels, at the same time attempting to maximize either strength or heat of hydration at 1 and 3 days. The inclusion of supplementary cementitious materials such as blast …

Experiment On Activated Carbon Manufactured From Waste Coffee Grounds On The Compressive Strength Of Cement Mortars, Sukjoon Na, Sanghoon Lee, Sungmin Youn

All Engineering Faculty Research

In this paper, we performed an experiment with activated carbon manufactured from waste coffee grounds on the compressive strength of normal cement mortars. The activated carbon reinforcement was manufactured from waste coffee grounds, and the collected coffee grounds were then transformed into activated carbon granules through the physical activation process. The activated carbon/cement composites were prepared by mixing cement with activated carbon granules with the weight fractions of 0.5%, 1%, 1.5%, 5%, and 10% cement. The experimental results show that adding activated carbon up to 1.5 wt% increased the early strength of cement mortars. Furthermore, we found that the composites …

Actuating A Magnetic Shape Memory Element Locally With A Set Of Coils, Andrew Armstrong, Peter Müllner

Materials Science and Engineering Faculty Publications and Presentations

The local actuation of a magnetic shape memory (MSM) element as used in an MSM micropump is considered. This paper presents the difference between an electromagnetic driver and a driver that uses a rotating permanent magnet. For the magnetic field energy of the permanent magnetic drive, the element takes in a significant stray field. In a particular case, energy reduction was 12.7 mJ. For an electromagnetic drive with an identical size of the MSM element, the total magnetic field energy created by the system was 2.28 mJ. Attempts to experimentally nucleate twins in an MSM element by energizing an electromagnetic …

A Foray Into Laboratory Scale Soil Incubations With Corn Stover And High Lignin Fermentation Byproduct, Michelle Wang

ENGS 88 Honors Thesis (AB Students)

As the production of biofuels increases to meet the demands of a growing low carbon economy, questions of sustainability surrounding its feedstock and waste streams have become increasingly relevant. In the biofuel production process, crop residues like corn stover are harvested from the field and converted to biofuels leaving generating a residue called high lignin fermentation byproduct (HLFB). From extensive process modelling in the literature, it is suggested that HLFB should be either combusted to fuel auxiliary conversion processes or returned to the soil in place of the crop residues that were harvested. Currently, there is little literature testing the …

Securing Pint Glasses On Serving Trays With Magnetic Attachments, Jayden Commendatore

Senior Theses

It is extremely common for servers in the restaurant industry to have pint glasses slip off their serving tray, wasting both time and money for the restaurant. I have designed a sleeve attachment that will clip on to the bottom of a pint glass. The metal sleeve attachment will be attracted to a magnet placed into the serving tray. This increases the normal force of the pint glass, resulting in an increase in the friction force between the tray and sleeve attachment, and helping secure the glass to the tray. In order to optimize the design, the value of the …

Relationship Between Thermal Conductivity And Free Electrons In Metal, Yansong Liu

Senior Theses

An experiment was designed and conducted to explore the relationship between thermal conductivity with free electrons in metal. In the experiment, copper, iron, aluminum, and titanium rods with close diameters were used to carry out the experiment. Each rod was heated up by a heat unit at one end while cooled on the other end with a heat sink to maintain a steady state. DC current was applied to rods in the direction along, as well as against, the heat flow. Thermal conductivities were measured in these two situations for each rod. Results showed electrons do dominate thermal flow inside …

Statistical Study Of The Effect Of Implementing An Airveyor System On The Warpage Of Injection Molded Closures, Charles Wesley Bozarth

Masters Theses & Specialist Projects

Berry Global in Bowling Green, Kentucky produces predominantly polypropylene container closures. One variant, the 83mm lined jar closure, is produced by first being injection molded, placed in work-in-progress (WIP) hold for 24 hours to cool, and then finished through the auxiliary liner operation into a final product. While this process is an effective method to produce a quality large-diameter closure and allows the polypropylene adequate time to cool without warping out of shape, the 24-hour WIP time and the manpower needed to accomplish this can negatively impact several business metrics as well as employee safety.

The purpose of this thesis …

Damage Evolution And High-Rate Response Of High-Strength Concrete Under Triaxial Loading, Brett Williams

Mechanical Engineering Research Theses and Dissertations

The research presented in this study focuses on understanding fundamental mechanisms that drive material response under dynamic loading conditions. The objectives of the research were to: (1) to understand damage initiation and propagation in the bulk geomaterial under a variety of loading conditions and (2) to systematically investigate the strain rate effects on the triaxial compressive response of cementitious materials through the development of an innovative, first of its kind large-diameter (50 mm) triaxial Kolsky bar system.

The triaxial compressive response of high-strength concrete is needed to understand pressure-dependent material behavior, which is important for modeling extreme loading events. However, …

Adsorption And Surface Diffusion Of Metals On Α-Al2O3 For Advanced Manufacturing Applications, Austin Biaggne, Gregory Noble, Lan Li

Materials Science and Engineering Faculty Publications and Presentations

The adsorption and diffusion of Mo and Nb adatoms on the α-Al₂O₃ (0001) surface were explored using density functional theory-based methods. Adsorption energies of Mo and Nb adatoms at minima sites on the surface were determined. Mo and Nb adatoms prefer to adsorb to the same locations on the surface, and larger adsorption energies calculated for Nb compared to Mo indicate that Nb adatom-surface interactions are stronger than Mo. Using minima adsorption sites as initial and final locations for surface diffusion, energy barriers for diffusion were calculated using the nudged elastic band method. Overall, Mo and …

Experimental Study Of Hollow-Core Slab Containing Waste Pet Bottles, Mulia Orientilize, Josia Irwan Rastandi, R. M. Dimas Aries C., Marsha Niken P., Krisna Adi S.S., Abimantrana Abimantrana

Makara Journal of Technology

This study investigated the utilization of plastic-waste concrete as an effort to reduce urban waste problems. The waste plastic bottles were utilized to form the hollows of the hollow-core slabs (HCSs). The bottles were made of polyethylene terephthalate (PET). As a part of green research to reuse waste material, shredded PET was also added to the concrete mixture to improve the HCS strength. The cast-in-site HCS could be constructed without any difficulties. Three parameters were investigated: the effects of void content, shredded PET content, and steel-fiber (SF) content on the HCS ultimate bending capacity (Mu). Fifteen specimens were tested under …