Materials Science and Engineering Commons^™

Wear Of High Entropy Alloys: Understanding Effects Of Cryogenic Temperatures And Surface Nitriding On Wear Behavior, Aubrey Yu Tang

Dartmouth College Ph.D Dissertations

Cryogenic tribological applications have become increasingly important with the development and innovation of advanced equipment in aerospace, polar regions, superconductivity, and more. Traditional lubrication methods are not viable under these harsh environments, so metallic materials must be able to maintain excellent mechanical properties and withstand the constant impact and wear alone. High entropy alloys (HEAs) have emerged as potential candidates for these applications because of their wide variety of excellent room temperature properties and apparent improvement of mechanical properties of some HEAs at extremely low temperatures. Despite their promising nature, very limited work has been done on understanding the wear …

64th Annual Rocky Mountain Conference On Magnetic Resonance

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 64th annual meeting of the Rocky Mountain Conference on Magnetic Resonance. Held in the Snowbird Resort and Conference Center, Snowbird, Utah, August 3-7, 2025.

Understanding Structure-Property Relationships Within Polyolefin-Derived Vitrimer Systems, Mikaela Sadri

Dissertations

Polyolefins are extremely ubiquitous materials due to their satisfactory material properties, ease of synthesis, and low cost. Unfortunately, their extensive use has led to a global plastic waste mismanagement problem. As such, notable efforts have recently focused on converting these commodity polymers into vitrimers, or dynamic networks, to extend their use-life and tailor their properties. However, the fundamental polymer physics of these emerging materials, remain largely underexplored, hindering their widespread implementation. To address this challenge and enable a more sustainable future, the overarching goal of my dissertation research is to understand the fundamental structure-property relationships within complex polyolefin-derived vitrimer systems. …

Advancing Lithium-Ion Batteries Through Exploration Of Novel Physico-Chemical Phenomena, Peshal Karki

All Dissertations

Lithium-ion batteries (LIBs) power a wide range of modern devices, from smartphones to electric vehicles. This dissertation integrates materials characterization and electrochemical testing to develop novel Si-based electrode materials, investigate separator effects, and improve electrochemical impedance spectroscopy (EIS) modeling. First, I synthesized Si@CC composites using bio-based carbon sources and discovered a novel in situ disorder reduction in the amorphous carbon cloud during cycling, attributed to Si volume fluctuations and mesoporous carbon structure, which enhanced capacity retention. A binder-free electrode (Si@CC@BP) using bucky paper further improved gravimetric and areal capacities while reducing weight and manufacturing complexity.

Next, I investigated how separator …

Ferroelectricity And Multiferroicity In Ultrathin Films Of Unconventional Transition Metal Oxide, Xin Li

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Ferroic orders of transition metal oxides, such as ferroelectricity and ferromagnetism, are determined by the intercoupling between spin, charge, lattice. Consequently, ferroic epitaxial thin films have attracted wide interest due to the profuse novel phenomena and the great application potentials for modern electronics. However, the mainstream of the study for transition metal oxides has focused on perovskite structure, limiting the understanding and discovery of novel phenomena associate with ferroic orders. In this thesis, the epitaxial films of hexagonal rare-earth ferrites (h-RFeO₃) and fluorite-structure hafnia oxide (HfO₂) are studied comprehensively, providing new experimental and theoretic …

Enhancing The Design Of Strained Superlattice Gallium Arsenide Based Photocathodes With Distributed Bragg Reflector, Adam D. A. Masters

Electrical & Computer Engineering Theses & Dissertations

Particle accelerators play a crucial role in our understanding of matter and the universe and have numerous practical applications in various fields. These devices enable scientists to examine the smallest components of matter, study the forces that govern their interactions, and probe conditions from the early universe. Moreover, accelerators are valuable in medicine, industry, and research, enhancing imaging methods, cancer therapies, and manufacturing techniques. As the experiments conducted at these facilities evolve and require higher precision, improved particle sources must continue to advance to keep up with their requirements. To do that, we enhanced the design of spin polarized electron …

A Strict Physicality-Preserving Scheme For A 2d Q-Tensor Flow With A Singular Potential, Md Mashud Parvez

Mathematics & Statistics Theses & Dissertations

Nematic liquid crystals are a state of matter that exhibit properties between those of conventional liquids and solid crystals. Their unique ability to align molecules in specific directions makes them essential in various applications, including display technologies and advanced materials. To model their complex behavior, mathematical frameworks such as the Q-tensor model are used to describe the orientation and degree of molecular order. In this work, we introduce a numerical scheme for a two-dimensional (2D) dynamic Q-tensor model, which is formulated as an L²-gradient flow driven by the liquid crystal free energy and incorporates a singular potential to …

Two Analytic Issues Arising From Models In Probability And Materials Science, Giang Vu Thanh Nguyen

Mathematics & Statistics Theses & Dissertations

This dissertation explores two distinct topics centered on mathematical models in probability theory and materials science. The first part investigates a series of functions derived from an adaptive algorithm designed to address the score-based secretary problem, a classic challenge in probability theory. This problem involves making immediate decisions to select the best candidate from a sequence of interviews. The algorithm aims to maximize the probability of selecting the optimal candidate based on observed scores. We prove two fundamental analytic properties of this sequence of functions as a theoretic support of the algorithm: first, the functions in the sequence each possess …

Synthesis, Structural Characterization And Optical Studies Of Silver-Indium-(Zinc)-Chalcogenide Fluorescent Quantum Dots, Sujal Acharya

Graduate Theses and Dissertations

Developing a non-toxic, high-performance fluorescent nanomaterial is crucial for overcoming the environmental and health restrictions of current cadmium, and lead based quantum dots (QDs), which limit the application of quantum dots in optoelectronics and bioimaging. In this thesis, we synthesized environmentally friendly AgInS2 QDs by a colloidal method, systematically altering the In/Ag precursor ratio from 2 to 6 to study the impact on their optical and photophysical properties. Our goals were to find the optimal stoichiometry for maximum quantum efficiency and stability. We also investigated further improving optical and photophysical properties through shelling with ZnS. The emission spectra appeared broad, …

Discovering And Designing Novel Perovskite Photovoltaic Materials Via Machine Learning, Junyeong Ahn

Discovery Undergraduate Interdisciplinary Research Internship

Perovskite semiconductors are promising materials for high-efficiency photovoltaics due to their outstanding optoelectronic properties, emerging as a sustainable energy source through solar cell applications. Perovskites with the ABX₃ composition (A, B = metal or organic cations with varying oxidation states; X = chalcogen or halogen anions) have gained interest for their excellent phase stability and compositional tunability. However, combinatorial possibilities arising from the many choices of A, B, and X site species, and their respective mixing fractions, a large number of possible ABX₃ perovskites remain undiscovered. In this work, we used machine learning (ML) methods to design new stable and …

Numerical Simulation Of The Pitting Corrosion Behavior Of Stainless Steel Bellows Influenced By Varying Liquid Film Thicknesses, Lu-Jun Ren, Guo-Min Li, Zhen-Xiao Zhu, Hai-Yan Xiong, Bing Li

Journal of Electrochemistry

To advance the understanding of the corrosion behavior of stainless steel bellows in marine atmospheric environments and enhance the precision of service life predictions, this study employs finite element simulations to investigate the pitting corrosion rates and pit morphologies of bellows peaks and troughs under varying electrolyte film thicknesses. The model incorporates localized electrochemical reactions, oxygen concentration, and homogeneous solution reactions. For improved computational accuracy, the fitted polarization curve data were directly applied as nonlinear boundary conditions on the electrode surface via interpolation functions. Simulation results reveal that the peak regions exhibit faster corrosion rates than the trough regions. With …

Research Progress On Thermal Management Of Lithium-Ion Batteries, Hong-Da Li, Qiu-Wan Shen, Zhao-Yang Zhang, Xin-Yue Zhao, Yuan Wei, Shi-An Li

Journal of Electrochemistry

Nowadays, new energy technologies are developing rapidly, energy storage systems are widely used, and lithium-ion batteries occupy a dominant position among them. Therefore, it is also very important to ensure their performance, safety and service life through thermal management technology. In this paper, the causes of thermal runaway of lithium batteries are reviewed firstly, and three commonly used thermal management technologies, namely, air cooling, liquid cooling and phase change material cooling, are compared according to relevant literature in recent years. Air cooling technology has been widely studied because of its simple structure and low cost, but its temperature control effect …

Regulating The Amount Of Graphene Oxide For Enhanced Capacitive Energy Storage Of Mof Derived Materials, Yong-Ji Qin, Jing-Quan Yang, Hao Wang, Mei-Ling Lian, Pei-Pei Jia, Jun Luo, Xi-Jun Liu, Jun-Feng Liu

Journal of Electrochemistry

In pursuit of more efficient and stable electrochemical energy storage materials, composite materials consisting of metal oxides and graphene oxide have garnered significant attention due to their unique structures and exceptional properties. Graphene oxide (GO), a two-dimensional material with an extremely high specific surface area and excellent conductivity, offers new possibilities for enhancing the electrochemical performance of metal oxides. In this work, we synthesized metal- organic framework (MOF) and GO composites by regulating the amount of GO, and successfully prepared composites of metal oxides supported by nitrogen-doped carbon frameworks and GO through a simple one-step calcination process. Based on the …

Investigating The Thixotropy Of Fresh Struvite Cement-Based Composite: Insights On Mechanisms Of The Pastes’ Thixotropic Behavior, Ugochukwu Ewuzie, Abdulkareem O. Yusuf, Damilola Daramola, Monday Uchenna Okoronkwo

Chemical and Biochemical Engineering Faculty Research & Creative Works

Struvite (ST) recovered during wastewater treatment has been sparsely applied in cement-based composites. This study systematically evaluated the thixotropic behavior of cement-struvite (CST) pastes, a mix of 5–20 % ST by mass of cement, and proposed the interaction mechanisms leading to the pastes' thixotropy. The hysteresis loop area was used to establish the pastes' thixotropy and investigate its relationship with increased ST content, temperature, and yield stress. In the thixotropic behavior model used, the equilibrium shear stress was employed to examine the CST pastes' irreversible change; the characteristic time of deflocculation was used to study the flocs destruction process; and …

Vacuum Consistent Electrochemistry In Ionic Liquid Combined With Oxide Epitaxy, Yuji Matsumoto

Journal of Electrochemistry

We introduce our state-of-the art of “vacuum consistent electrochemistry” to an investigation of the interfaces between oxides and ionic liquid (IL). Pulsed laser deposition (PLD) has been one of the powerful and sophisticated techniques to realize nanoscale preparation of high-quality epitaxial oxide thin films. On the other hand, electrochemistry is a simple, very sensitive, and non-destructive analysis technique for solid-liquid interfaces. To ensure the reproducibility in experiment of the interfaces of such epitaxial oxide films, as well as bulk oxide single-crystals, with IL, we employ a home-built PLD-electrochemical (EC) system with IL as an electrolyte. The system allows one to …

Pm Irras Studies Of Organized Molecular Films At A Gold Electrode Surface, Zhang-Fei Su, Ai-Cheng Chen, Jacek Lipkowski

Journal of Electrochemistry

This feature article illustrates the potential of polarization modulation infrared reflection absorption spectroscopy (PM IRRAS) to provide molecular-level information about the structure, orientation and conformation of constituents of thin films at electrode surfaces. PM IRRAS relies on the surface selection rules stating that the p-polarized IR beam is enhanced, while the s-polarized beam is attenuated at the metal surface. The difference between p- and s-polarized beams eliminates the background of the solvent and provides IR spectra at a single electrode potential. In contrast, two other popular in situ IR spectroscopic techniques, namely, subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS) …

Redox-Active Monolayers On Ito Prepared By Post-Amidation And Direct Esterification And Their Spectroelectrochemical Characterization, Takamasa Sagara, Sae Nakai, Ryusuke Yofu, Shota Kojin

Journal of Electrochemistry

A redox-active monolayer on an optically transparent electrode constitutes a typical platform for spectroelectrochemical sensing. The necessity for its sophistication arises from the availability of multi-dimensional sensing signals. Simultaneous monitoring of the redox current and color change synchronized with the oxidation state change significantly enhances sensitivity and selectivity. This study aimed to elucidate the modification of an indium tin oxide (ITO) electrode with a viologen monolayer with an ordered orientation. Novel methods were developed to immobilize a viologen molecule bearing a carboxyl group to form assembled monolayers through a condensation reaction using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide with N-hydroxy-succinimide (EDC/NHS). In the two methods …

Ambient Co2 Capture And Valorization Enabled By Tandem Electrolysis Using Solid-State Electrolyte Reactor, Yan-Bo Hua, Bao-Xin Ni, Kun Jiang

Journal of Electrochemistry

Electrocatalytic carbon dioxide reduction is a promising technology for addressing global energy and environmental crises. However, its practical application faces two critical challenges: the complex and energy-intensive process of separating mixed reduction products and the economic viability of the carbon sources (reactants) used. To tackle these challenges simultaneously, solid-state electrolyte (SSE) reactors are emerging as a promising solution. In this review, we focus on the feasibility of applying SSE for tandem electrochemical CO₂ capture and conversion. The configurations and fundamental principles of SSE reactors are first discussed, followed by an introduction to its applications in these two specific areas, …

Poly(Pyridinium Salt)S Containing 9,9-Bis(4- Aminophenyl)Fluorene Moieties With Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline And Light-Emitting Properties, Pradip K. Bhowmik, David King, Haesook Han, Andras F. Wacha, Matti Knaapila

Chemistry and Biochemistry Faculty Research

Main-chain conjugated and non-conjugated polyelectrolytes are an important class of materials that have many technological applications ranging from fire-retardant materials to carbon-nanotube composites, nonlinear optical materials, electrochromic materials for smart windows, and optical sensors for biomolecules. Here, we describe a series of poly(pyridinium salt)s-fluorene containing 9,9-bis(4-aminophenyl)fluorene moieties with various organic counterions that were synthesized using ring-transmutation polymerization and metathesis reactions, which are non-conjugated polyelectrolytes. Their chemical structures were characterized by Fourier transform infrared (FTIR), proton (1H) and fluorine 19 (19F) nuclear magnetic resonance (NMR) spectrometers, and elemental analysis. They exhibited polyelectrolytic behavior in dimethyl sulfoxide. Their lyotropic liquid-crystalline phases were …

Study On Reasonable Parameters Of Natural Smoke Exhaust Shafts In Tunnels With Different Longitudinal Slopes, Yang Tao, Zeng Yuekai, Li Peijun, Ren Rui, Deng Min, Zhang Aoyu

Journal of China & Foreign Highway

To obtain the reasonable parameters of a smoke exhaust shaft in a tunnel under different longitudinal slope conditions,the temperature,flow velocity,and smoke exhaust efficiency of the tunnel were taken as indexes,and the numerical model was established by using fire dynamics simulator (FDS ) software to study the influence of the longitudinal slope of the tunnel,shaft width,and shaft length on the ventilation and smoke exhaust in case of a fire.The results show that under the longitudinal slope conditions,with the increase in the shaft width and length,the maximum temperature in the tunnel decreases,and the smoke exhaust efficiency of the shaft increases.However,the influence of …

Study On Salt Release Mechanism Of Self-Melting Ice Asphalt Mixture And Its Impact On Road Performance, Li Tao, Zhang Xiu ’Ang

Journal of China & Foreign Highway

To study the long-term salt release characteri stics of self-melting ice asphalt mixture and the impact of the complete salt release on pavement durability,an accelerated salt release method was developed using a Los Angeles abrasion tester.The salt release mechanism under varying asphalt types,deicing agent contents,and gradation types was revealed.The impact of the complete salt release on road performance was analyzed.Results show that the Los Angeles abrasion tester-based salt release method achieves 91 times and 114 times higher salt release efficiency than the magnetic stirrer and natural immersion methods,respectively.SBS-modified asphalt mixture exhibits a longer salt release duration.The salt release duration is …

Research On Size Effect On Cubic Compressive Strength Of Ground Granulated Blast Furnace Slag-Fly Ash Stabilized Large-Size Macadam, Liu Qunyan, Liu Liping, He Miao, Yuan Lingqing, Zhang Liang

Journal of China & Foreign Highway

To analyze the effect of specimen size on the compressive strength of ground granulated blast furnace slag-fly ash (GGBFS-FA ) stabilized large-size macadam,the 200 mm × 200 mm × 200 mm cubic specimen and 3 d compressive strength were designated as a reference specimen and strength in this study,and numerical simulations of compressive strength were performed by using a discrete element method for GGBFS-FA stabilized large-size macadam specimens with a maximum particle size (dmax) of 73 mm and five side lengths of 2.0dmax,2.5dmax,3.0dmax,3.5dmax,and 4.0dmax.The size effect mechanism on the mixture ’s compressive strength was revealed from the perspective of energy.By …

Effect Of Mineral Admixtures On Properties Of Shotcrete, Ma Kaikai, Zhao Feng, Sun Rongxiao, Han Song, Hu Peng, Wang Kun

Journal of China & Foreign Highway

To study the influence of different mineral admixtures on the properties of shotcrete,the effects of four kinds of mineral admixtures including fly ash,silica fume,metakaolin,and carbon black on the rebound rate,one-shot thickness,and compressive strength of shotcrete were analyzed through tests on concrete rebound rate,one-shot thickness,and compressive strength.The results show that:① as the content of carbon black,silica fume,and metakaolin increases from 5% to 10%,the rebound rate of shotcrete decreases by 25.76%,16.46%,and 16.70%,respectively;② carbon black and silica fume have a good effect on increasing the one-shot thickness of concrete.When the content of carbon black and silica fume is 10%,the one-shot thickness exceeds 35 …

Study On Rheological Properties Of Basalt Fiber Asphalt Mastic Modified With Silane Coupling Agent, Liu Yuande, Zheng Nanxiang, Zhang Xiang, Gao Haiwei, Zhang Bowen

Journal of China & Foreign Highway

To investigate the rheological properties of basalt fiber asphalt mastic,a silane coupling agent was used as a modifier for basalt fibers,and the effects of varying fiber contents were analyzed. Cone penetration tests,bending beam rheological tests,and dynamic shear rheometer tests were conducted to evaluate the rheological properties of asphalt mastic consistency, high-temperature stability,and low-temperature cracking resistance under different temperatures and fiber contents.The findings show that the silane-coupled basalt fibers enhance the shear strength and consistency of asphalt mastic.After modification,the phase angle decreases;elastic response increases,and complex modulus improves.Adsorption capacity between fibers and asphalt increases significantly,enhancing high-temperature deformation resistance and low-temperature cracking resistance …

Analysis Of Mechanical Properti Es Of Integral Jacking Basket Arch Bridge During C Onstruction, Chen Tao, Qiu Jingkui, Wang Ji

Journal of China & Foreign Highway

Taking the Xindian Bridge in Ni ngbo as the background,this paper analyzed the mechanical properties of the integral jacking basket arch bridge during construction.Midas finite element software was used to establish the spatial model of the main bridge,and the deviation of the suspender force and support reaction force of the completed bridge from the design was 1.84% and 1.8%,respectively.The maximum deviation of the displacement calculation of the tie beam at the bridge completion stage was 22 mm,and the maximum deviation of the displacement of the arch rib at the same stage was ‒ 12 mm,which showed that the finite element …

Internal Force Optimization In Com Pleted Stage And Construction Alignment Control Of Super Long-Span Extradosed Cable-Stayed Bridge, Ba Wenpeng

Journal of China & Foreign Highway

This paper is based on a super long-span extradosed cable-stayed bridge with a main span of 400 m.In view of the technical challenges of high negative bending moment at the quarter point of the bridge and large deformation during the cantilever assembly process in the non-cable area,a systematic solution was proposed in combination with the entire construction process.This paper proposed three schemes:permanent cable over-tensioning,temporary cable setting,and large segment closure.The bending moment ratio (λM) and structural deformation were used as quantitative indicators,and a finite element model was established to compare the three schemes.The results show that all three schemes can improve …

Comparative Study On Differences In Asphalt Pavement Design Between China And Southern Africa, Wang Qing, Lin Yangyang, Yan Hongxiang, Zhao Bin, Xia Moxuan, Li Ning, Si Wei

Journal of China & Foreign Highway

To facilitate the successful implementation of projects in the Southern Africa region and promote the application and internationalization of China ’s standards,this study compared the asphalt pavement design systems,construction materials,design parameters,and structural design methods of both regions based on the main asphalt pavement design specifications currently in use in China and Southern Africa.The results show that among Southern African countries,South Africa has a comprehensive and widely applied standard system,while other Southern African countries adopt more varied and less theoretical standards.In contrast,China ’s standard system is complete and highly practical.Due to differences in regional climates,the selection principles and mechanical requirements for …

Discontinuous Deforma Tion Analysis Of Progressive Toppling Of Rock Slopes With Fractured Slab Structure, Yuan Sifan, Li Tonglu, Haider Mumtaz, Zhang Changliang, Li Ping

Journal of China & Foreign Highway

Progressive toppling of rock sl opes with fractured slab structures is quite common in the slopes of hydropower and highway engineering,posing a potential safety risk during both construction and operational phases.The field investigation found that progressive toppling mostly occurs on slopes with concentrated tectonic stress,intense river incision,and high steepness.Typically,these slopes are composed of hard,thinly-layered,and overthrusted rock mass with a fractured slab structure.From a macroscopic point of view,progressive toppling failure is neither a collapse nor a slide but a form of discontinuous deformation.The traditional limit equilibrium method for slope stability analysis is not suitable for evaluating such slopes.In this paper,by taking …

Prediction For Humidity Adjustment Factor And Dry-Wet Cycle Reduction Factor Of Resilient Modulus Of Subgrade Soil Based On Ann, Wang Xufeng, Fu Wei, Peng Junhui, Hu Jiankun, Zhang Junhui, Li Zhiguang

Journal of China & Foreign Highway

Existing methods for determining the humidity adjustment factor and dry-wet cycle reduction factor of the resilient modulus of subgrade soil are mostly based on laboratory tests that consume a large amount of manpower and time,and the prediction accuracy is limited due to the constraints of specification value ranges.In order to achieve fast and accurate prediction of these two factors,the effects of stress state,moisture content,and the number of dry-wet cycles on the resilient modulus of subgrade soil were investigated through laboratory dynamic triaxial tests.Based on existing literature,physical parameters,state parameters,and stress parameters of subgrade soil were selected,and an artificial neural network prediction …

Semi-Flexible Pavement Structure Analysis Based On Double Modulus Theory, Pan Qinxue, Zhou Shurui, Hu Jia, Zhang Long, Song Xiaojin, Liu Hongfu

Journal of China & Foreign Highway

Semi-flexible pavement materials have significant differences in tension and compression.If the mechanical response analysis of pavement structures is conducted by using the traditional linear elastic theory with a single modulus,there will be a considerable deviation from actual situations.To analyze and optimize semi-flexible pavement structures,this paper compared the changes in key mechanical responses of pavement structures under six different semi-flexible layer positions and thickness combinations based on the double modulus theory.The results show that there is a significant difference in the calculation results of key mechanical responses of the pavement based on the double modulus theory and the single modulus theory,with …