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Articles 1 - 30 of 37
Full-Text Articles in Analytical Chemistry
Amphiphilic Block Copolymer Micelles In Selective Solvents: The Effect Of Solvent Selectivity On Micelle Formation, Labeesh Kumar, Andriy Horechyy, Eva Bittrich, Bhanu Nandan, Petra Uhlmann, Andreas Fery
Amphiphilic Block Copolymer Micelles In Selective Solvents: The Effect Of Solvent Selectivity On Micelle Formation, Labeesh Kumar, Andriy Horechyy, Eva Bittrich, Bhanu Nandan, Petra Uhlmann, Andreas Fery
Chemistry Department: Faculty Publications
We investigated the micellar behavior of a series of asymmetric polystyrene-block-poly (4-vinylpyridine) (PS-b-P4VP) block copolymers in different P4VP-selective alcoholic solvents. The micellar behavior was further correlated with the spectroscopic ellipsometry results obtained on swelling of PS and P4VP polymer films in the corresponding solvent vapors. The time-resolved (in situ) dynamic light scattering (DLS) measurements, in combination with (ex situ) electron microscopy imaging, revealed information about the aggregation state of PS-b-P4VP BCP in different alcohols and the effect of heat treatment. The ellipsometry measurements allowed us to estimate the difference in solvent selectivity toward PS/P4VP pair. Both DLS and ellipsometric studies …
Medium-Dependent Antibacterial Properties And Bacterial Filtration Ability Of Reduced Graphene Oxide, Alexander Gusev, Olga Zakharova, Dmitry S. Muratov, Nataliia S. Vorobeva, Mamun Sarker, Iaroslav Rybkin, Daniil Bratashov, Evgeny Kolesnikov, Aleš Lapanje, Denis V. Kuznetsov, Alexander Sinitskii
Medium-Dependent Antibacterial Properties And Bacterial Filtration Ability Of Reduced Graphene Oxide, Alexander Gusev, Olga Zakharova, Dmitry S. Muratov, Nataliia S. Vorobeva, Mamun Sarker, Iaroslav Rybkin, Daniil Bratashov, Evgeny Kolesnikov, Aleš Lapanje, Denis V. Kuznetsov, Alexander Sinitskii
Chemistry Department: Faculty Publications
Toxicity of reduced graphene oxide (rGO) has been a topic of multiple studies and was shown to depend on a variety of characteristics of rGO and biological objects of interest. In this paper, we demonstrate that when studying the same dispersions of rGO and fluorescent Escherichia coli (E. coli) bacteria, the outcome of nanotoxicity experiments also depends on the type of culture medium. We show that rGO inhibits the growth of bacteria in a nutrition medium but shows little eect on the behavior of E. coli in a physiological saline solution. The observed eects of rGO on E. coli in …
Reversing Interfacial Catalysis Of Ambipolar Wse2 Single Crystal, Zegao Wang, Hong-Hui Wu, Qiang Li, Flemming Besenbacher, Yanrong Li, Xiao Cheng Zeng, Mingdong Dong
Reversing Interfacial Catalysis Of Ambipolar Wse2 Single Crystal, Zegao Wang, Hong-Hui Wu, Qiang Li, Flemming Besenbacher, Yanrong Li, Xiao Cheng Zeng, Mingdong Dong
Chemistry Department: Faculty Publications
An improved understanding of the origin of the electrocatalytic activity is of importance to the rational design of highly efficient electrocatalysts for the hydrogen evolution reaction. Here, an ambipolar single-crystal tungsten diselenide (WSe2) semiconductor is employed as a model system where the conductance and carrier of WSe2 can be individually tuned by external electric fields. The field-tuned electrochemical microcell is fabricated based on the single-crystal WSe2 and the catalytic activity of the WSe2 microcell is measured versus the external electric field. Results show that WSe2 with electrons serving as the dominant carrier yields much higher activity than WSe2 with holes …
Understanding Interactions Of Citropin 1.1 Analogues With Model Membranes And Their Influence On Biological Activity, Nathalia Rodrigues De Almeida, Jonathan Catazaro, Maddeboina Krishnaiah, Yashpal Singh Chhonker, Daryl J. Murry, Robert Powers, Martin Conda-Sheridan
Understanding Interactions Of Citropin 1.1 Analogues With Model Membranes And Their Influence On Biological Activity, Nathalia Rodrigues De Almeida, Jonathan Catazaro, Maddeboina Krishnaiah, Yashpal Singh Chhonker, Daryl J. Murry, Robert Powers, Martin Conda-Sheridan
Chemistry Department: Faculty Publications
The rapid emergence of resistant bacterial strains has made the search for new antibacterial agents an endeavor of paramount importance. Cationic antimicrobial peptides (AMPs) have the ability to kill resistant pathogens while diminishing the development of resistance. Citropin 1.1 (Cit 1.1) is an AMP effective against a broad range of pathogens. 20 analogues of Cit 1.1 were prepared to understand how sequence variations lead to changes in structure and biological activity. Various analogues exhibited an increased antimicrobial activity relative to Cit 1.1. The two most promising, AMP-016 (W3F) and AMP-017 (W3F, D4R, K7R) presented a 2- to 8-fold increase in …
A Panel Of Protein Kinase Chemosensors Distinguishes Different Types Of Fatty Liver Disease, Jon R. Beck, Fatima Cabral, Karuna Rasineni, Carol A. Casey, Edward N. Harris, Cliff I. Stains
A Panel Of Protein Kinase Chemosensors Distinguishes Different Types Of Fatty Liver Disease, Jon R. Beck, Fatima Cabral, Karuna Rasineni, Carol A. Casey, Edward N. Harris, Cliff I. Stains
Chemistry Department: Faculty Publications
The worldwide incidence of fatty liver disease continues to rise, which may account for concurrent increases in the frequencies of more aggressive liver ailments. Given the existence of histologically identical fatty liver disease subtypes, there is a critical need for the identification of methods that can classify disease and potentially predict progression. Herein, we show that a panel of protein kinase chemosensors can distinguish fatty liver disease subtypes. These direct activity measurements highlight distinct differences between histologically identical fatty liver diseases arising from diets rich in fat versus alcohol and identify a previously unreported decrease in p38α activity associated with …
Systematic Optimization For Production Of The Anti-Mrsa Antibiotics Wap-8294a In An Engineered Strain Of Lysobacter Enzymogenes, Xusheng Chen, Shanren Li, Lingjun Yu, Amanda Miller, Liangcheng Du
Systematic Optimization For Production Of The Anti-Mrsa Antibiotics Wap-8294a In An Engineered Strain Of Lysobacter Enzymogenes, Xusheng Chen, Shanren Li, Lingjun Yu, Amanda Miller, Liangcheng Du
Chemistry Department: Faculty Publications
WAP-8294A is a group of cyclic lipodepsipeptides and considered as the first-in-class new chemical entity with potent activity against methicillin-resistant Staphylococcus aureus. One of the roadblocks in developing the WAP-8294A antibiotics is the very low yield in Lysobacter. Here, we carried out a systematic investigation of the nutritional and environmental conditions in an engineered L. enzymogenes strain for the optimal production of WAP-8294A. We developed an activity-based simple method for quick screening of various factors, which enabled us to optimize the culture conditions. With the method, we were able to improve the WAP-8294A yield by 10-fold in small-scale cultures and …
Electropolymerization And Characterization Of Thin Film Dielectrics, Christopher White Ii
Electropolymerization And Characterization Of Thin Film Dielectrics, Christopher White Ii
Department of Chemistry: Dissertations, Theses, and Student Research
Graphene is a two-dimensional allotrope of carbon, with several superlative properties, including high electron and hole conductivities, high tensile strength, and chemical robustness. Its chemical and physical properties make it attractive for in use in a myriad of applications, including transistors. However, graphene’s chemical inertness and its physical and electrical properties’ dependency on its conjugated structure make building composite materials with graphene difficult. In 2015, Lipatov, et. al. demonstrated that a film derived from electropolymerized phenol could be used as a dielectric layer on transistor devices fabricated from exfoliated graphene. This thesis extends that research, detailing experiments of phenol and …
Monolayer Triphosphates Mp3 (M = Sn, Ge) With Excellent Basal Catalytic Activity For Hydrogen Evolution Reaction, Hong-Hui Wu, He Huang, Jie Zhong, Song Yu, Qiaobao Zhang, Xiao Cheng Zeng
Monolayer Triphosphates Mp3 (M = Sn, Ge) With Excellent Basal Catalytic Activity For Hydrogen Evolution Reaction, Hong-Hui Wu, He Huang, Jie Zhong, Song Yu, Qiaobao Zhang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Atomically thin two-dimensional (2D) materials have received intense research interest due to their novel properties and promising applications in nanodevices. By using density functional theory (DFT) calculations, we investigate catalytic activities of several newly predicted two-dimensional (2D) triphosphides GeP3, SnP3 and InP3 monolayers for hydrogen evolution reaction (HER). The calculation results show that GeP3 and SnP3 monolayers are active catalysts for HER with suitable free energy of hydrogen adsorption in the basal plane. In particular, the Gibbs free energy of hydrogen adsorption (ΔGH*) of GeP3 is 0.024 eV, a value even …
Analysis Of Drug-Protein Interactions During Diabetes By High-Performance Affinity Chromatography, Pingyang Tao
Analysis Of Drug-Protein Interactions During Diabetes By High-Performance Affinity Chromatography, Pingyang Tao
Department of Chemistry: Dissertations, Theses, and Student Research
High-performance affinity chromatography (HPAC) is a type of liquid chromatography in which solutes are separated based on their binding to a stationary phase that is a biologically-related agent. Sulfonylurea drugs have significant binding to proteins in blood, with most of this binding is believed to occur with human serum albumin (HSA). HSA is known to be modified as a result of the high serum levels of glucose that is present during diabetes, which may also alter the function of HSA as a binding agent for many drugs in circulation. Some modifications of HSA that can occur during diabetes involves early …
Development Of Nanomaterial Supports For The Study Of Affinity-Based Analytes Using Ultra-Thin Layer Chromatography, Allegra Pekarek
Development Of Nanomaterial Supports For The Study Of Affinity-Based Analytes Using Ultra-Thin Layer Chromatography, Allegra Pekarek
Department of Chemistry: Dissertations, Theses, and Student Research
Ultra-thin layer chromatography (UTLC) is a growing field in analytical separations. UTLC is a branch of planar and liquid chromatography that is related to thin layer chromatography. The main advantage of UTLC compared to other techniques is it uses much less material, allowing for faster and more sensitive separations to take place. The UTLC devices fabricated in this project used either silicon oxide or silicon nanopillars deposited on a glass slide using glancing angle deposition (GLAD). Even a thin layer of these nanopillars deposited on a glass slide provide a large surface area for the analyte to be separated. GLAD …
Slips-Teng: Robust Triboelectric Nanogenerator With Optical And Charge Transparency Using A Slippery Interface, Wanghuai Xu, Xiaofeng Zhou, Chonglei Hao, Huanxi Zheng, Yuan Liu, Xiantong Yan, Zhengbao Yang, Michael Leung, Xiao Cheng Zeng, Ronald X. Xu, Zuankai Wang
Slips-Teng: Robust Triboelectric Nanogenerator With Optical And Charge Transparency Using A Slippery Interface, Wanghuai Xu, Xiaofeng Zhou, Chonglei Hao, Huanxi Zheng, Yuan Liu, Xiantong Yan, Zhengbao Yang, Michael Leung, Xiao Cheng Zeng, Ronald X. Xu, Zuankai Wang
Xiao Cheng Zeng Publications
Energy harvesting devices that prosper in harsh environments are highly demanded in a wide range of applications ranging from wearable and biomedical devices to self-powered and intelligent systems. Particularly, over the past several years, the innovation of triboelectric nanogenerators (TENGs) that efficiently convert ambient kinetic energy of water droplets or wave power to electricity has received growing attention. One of the main bottlenecks for the practical implications of such devices originates from the fast degradation of the physiochemical properties of interfacial materials under harsh environments. To overcome these challenges, here we report the design of a novel slippery lubricant-impregnated porous …
Diisopropylammonium Bromide Based Two-Dimensional Ferroelectric Monolayer Molecular Crystal With Large In-Plane Spontaneous Polarization, Liang Ma, Yinglu Jia, Stephen Ducharme, Jinlan Wang, Xiao Cheng Zeng
Diisopropylammonium Bromide Based Two-Dimensional Ferroelectric Monolayer Molecular Crystal With Large In-Plane Spontaneous Polarization, Liang Ma, Yinglu Jia, Stephen Ducharme, Jinlan Wang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
In light of their easy processing, light weight and mechanical flexibility, ferroelectric molecular crystal with large spontaneous polarization (Ps) is highly desired for many advanced applications. Herein, we report the first theoretical study of two-dimensional (2D) ferroelectric molecular crystals via ab initio calculations. Specifically, we show that diisopropylammonium bromide (DIPAB) based 2D ferroelectric monolayer molecular crystal with large in-plane Ps of ∼1.5 × 10−6 μC cm−1 can be achieved by slicing the bulk DIPAB along a specific plane while keeping the space group unchanged. The important roles of hydrogen bonds are …
Highly Stable And Efficient All-Inorganic Lead-Free Perovskite Solar Cells With Native-Oxide Passivation, Min Chen, Ming-Gang Ju, Hector F. Garces, Alexander D. Carl, Luis K. Ono, Zafer Hawash, Yi Zhang, Tianyi Shen, Yabing Qi, Ronald L. Grimm, Domenico Pacifici, Xiao Cheng Zeng, Yuanyuan Zhou, Nitin P. Padture
Highly Stable And Efficient All-Inorganic Lead-Free Perovskite Solar Cells With Native-Oxide Passivation, Min Chen, Ming-Gang Ju, Hector F. Garces, Alexander D. Carl, Luis K. Ono, Zafer Hawash, Yi Zhang, Tianyi Shen, Yabing Qi, Ronald L. Grimm, Domenico Pacifici, Xiao Cheng Zeng, Yuanyuan Zhou, Nitin P. Padture
Chemistry Department: Faculty Publications
There has been an urgent need to eliminate toxic lead from the prevailing halide perovskite solar cells (PSCs), but the current lead-free PSCs are still plagued with the critical issues of low efficiency and poor stability. This is primarily due to their inadequate photovoltaic properties and chemical stability. Herein we demonstrate the use of the lead-free, allinorganic cesium tin-germanium triiodide (CsSn0.5Ge0.5I3) solid-solution perovskite as the light absorber in PSCs, delivering promising efficiency of up to 7.11%. More importantly, these PSCs show very high stability, with less than 10% decay in efficiency after 500 h …
Machine Learning Enabled Prediction Of Mechanical Properties Of Tungsten Disulfide Monolayer, Xinyu Wang, Dan Han, Yang Hong, Haiyi Sun, Jingzhi Zhang, Jingchao Zhang
Machine Learning Enabled Prediction Of Mechanical Properties Of Tungsten Disulfide Monolayer, Xinyu Wang, Dan Han, Yang Hong, Haiyi Sun, Jingzhi Zhang, Jingchao Zhang
Chemistry Department: Faculty Publications
One of two-dimensional transition metal dichalcogenide materials, tungsten disulfide (WS2), has aroused much research interest, and its mechanical properties play an important role in a practical application. Here the mechanical properties of h-WS2 and t-WS2 monolayers in the armchair and zigzag directions are evaluated by utilizing the molecular dynamics (MD) simulations and machine learning (ML) technique. We mainly focus on the effects of chirality, system size, temperature, strain rate, and random vacancy defect on mechanical properties, including fracture strain, fracture strength, and Young’s modulus. We find that the mechanical properties of h-WS2 surpass those of …
In Situ Monitoring Of Linear Rgd-Peptide Bioconjugation With Nanoscale Polymer Brushes, Evmorfia Psarra, Ulla Konig, Martin Muller, Eva Bittrich, Klaus-Jochen Eichhorn, Petra B. Welzel, Manfred Stamm, Petra Uhlmann
In Situ Monitoring Of Linear Rgd-Peptide Bioconjugation With Nanoscale Polymer Brushes, Evmorfia Psarra, Ulla Konig, Martin Muller, Eva Bittrich, Klaus-Jochen Eichhorn, Petra B. Welzel, Manfred Stamm, Petra Uhlmann
Chemistry Department: Faculty Publications
Bioinspired materials mimicking the native extracellular matrix environment are promising for biotechnological applications. Particularly, modular biosurface engineering based on the functionalization of stimuli-responsive polymer brushes with peptide sequences can be used for the development of smart surfaces with biomimetic cues. The key aspect of this study is the in situ monitoring and analytical verification of the biofunctionalization process on the basis of three complementary analytical techniques. In situ spectroscopic ellipsometry was used to quantify the amount of chemisorbed GRGDS at both the homopolymer poly(acrylic acid) (PAA) brush and the binary poly(N-isopropylacrylamide) (PNIPAAm)− PAA brushes, which was finally confirmed …
Molecular Insights Into Organic Particulate Formation, Manoj Kumar, Emily Burrell, Jason C. Hansen, Joseph S. Francisco
Molecular Insights Into Organic Particulate Formation, Manoj Kumar, Emily Burrell, Jason C. Hansen, Joseph S. Francisco
Chemistry Department: Faculty Publications
Carboxylic acids have been detected in particles collected in various regions of the world. Here, we use experiments and Born–Oppenheimer molecular dynamics simulations to better understand the mechanism of particle formation from gas phase mixtures of formic acid (HCOOH), (CH3)3N, and water vapor. A flow reaction cell coupled to two scanning mobility particle sizers has been used to measure particle size, absolute number of particles and kinetics of particle formation. Experimental results show that the addition of (CH3)3N to a mixture of HCOOH and water vapor results in a dramatic increase in …
Development Of A Microcolumn One-Site Immunometric Assay For A Protein Biomarker: Analysis Of Alpha1-Acid Glycoprotein In Serum, Chenhua Zhang, Shae Lott, William Clarke, David S. Hage
Development Of A Microcolumn One-Site Immunometric Assay For A Protein Biomarker: Analysis Of Alpha1-Acid Glycoprotein In Serum, Chenhua Zhang, Shae Lott, William Clarke, David S. Hage
Chemistry Department: Faculty Publications
A one-site immunometric assay based on affinity microcolumns was developed for the analysis of alpha1-acid glycoprotein (AGP) as a model protein biomarker. In this assay, a sample containing AGP was incubated with an excess amount of a labeled binding agent, such as fluorescein-labeled anti-AGP antibodies or Fab fragments. The excess binding agent was removed by passing this mixture through a microcolumn that contained an immobilized form of AGP, while the signal was measured for the binding agent-AGP complex in the non-retained fraction. Theoretical and practical factors were both considered in selecting the concentration of labeled binding agent, …
Role Of Water On The Rotational Dynamics Of The Organic Methylammonium Cation: A First Principles Analysis, Ross D. Hoehn, Joseph S. Francisco, Sabre Kais, Ali Kachmar
Role Of Water On The Rotational Dynamics Of The Organic Methylammonium Cation: A First Principles Analysis, Ross D. Hoehn, Joseph S. Francisco, Sabre Kais, Ali Kachmar
Chemistry Department: Faculty Publications
Understanding the degradation mechanisms of lead-halide perovskites (CH3NH3PbI3) under exposure to liquid/aerosol water is an essential problem within the photovoltaic community. Herein we investigate both the static and the dynamic properties of the methylammonuim cation (MA) as it coordinates with invading water molecules (MA.(H2O)n, n = 1, 2, 3, 4) using both stationary state quantum mechanics and first principle molecular dynamics simulations. Various solvation structures of MA were characterized by their stabilization energies, dipoles, and Maximally-Localized Wannier Function (MLWF) centers. Calculation – and analysis – of vibrational shifts in the …
High Initial Reversible Capacity And Long Life Of Ternary Sno2‑Co‑Carbon Nanocomposite Anodes For Lithium‑Ion Batteries, Pan Deng, Jing Yang, Shengyang Li, Tian-E Fan, Hong-Hui Wu, Yun Mou, Hui Huang, Qiaobao Zhang, Dong-Liang Peng, Baihua Qu
High Initial Reversible Capacity And Long Life Of Ternary Sno2‑Co‑Carbon Nanocomposite Anodes For Lithium‑Ion Batteries, Pan Deng, Jing Yang, Shengyang Li, Tian-E Fan, Hong-Hui Wu, Yun Mou, Hui Huang, Qiaobao Zhang, Dong-Liang Peng, Baihua Qu
Chemistry Department: Faculty Publications
The two major limitations in the application of SnO2 for lithium-ion battery (LIB) anodes are the large volume variations of SnO2 during repeated lithiation/delithiation processes and a large irreversible capacity loss during the first cycle, which can lead to a rapid capacity fade and unsatisfactory initial Coulombic efficiency (ICE). To overcome these limitations, we developed composites of ultrafine SnO2 nanoparticles and in situ formed Co(CoSn) nanocrystals embedded in an N-doped carbon matrix using a Co-based metal–organic framework (ZIF-67). The formed Co additives and structural advantages of the carbon-confined SnO2/ Co nanocomposite effectively inhibited Sn coarsening …
Detailed Characterization Of The Solution Kinetics And Thermodynamics Of Biotin, Biocytin And Haba Binding To Avidin And Streptavidin, Roberto F. Delgadillo, Timothy C. Mueser, Kathia Zaleta-Rivera, Katie A. Carnes, Jose Gonzalez-Valdez, Lawrence J. Parkhurst
Detailed Characterization Of The Solution Kinetics And Thermodynamics Of Biotin, Biocytin And Haba Binding To Avidin And Streptavidin, Roberto F. Delgadillo, Timothy C. Mueser, Kathia Zaleta-Rivera, Katie A. Carnes, Jose Gonzalez-Valdez, Lawrence J. Parkhurst
Chemistry Department: Faculty Publications
The high affinity (KD ~ 10−15 M) of biotin for avidin and streptavidin is the essential component in a multitude of bioassays with many experiments using biotin modifications to invoke coupling. Equilibration times suggested for these assays assume that the association rate constant (kon) is approximately diffusion limited (109 M-1s-1) but recent single molecule and surface binding studies indicate that they are slower than expected (105 to 107 M-1s-1). In this study, we asked whether these reactions in solution are diffusion controlled, which reaction model and thermodynamic …
Molecular Insights Into Cage Occupancy Of Hydrogen Hydrate: A Computational Study, Rui Ma, Hong Zhong, Jinxiang Liu, Jie Zhong, Youguo Yan, Jun Zhang, Jiafang Xu
Molecular Insights Into Cage Occupancy Of Hydrogen Hydrate: A Computational Study, Rui Ma, Hong Zhong, Jinxiang Liu, Jie Zhong, Youguo Yan, Jun Zhang, Jiafang Xu
Chemistry Department: Faculty Publications
Density functional theory calculations and molecular dynamics simulations were performed to investigate the hydrogen storage capacity in the sII hydrate. Calculation results show that the optimum hydrogen storage capacity is ~5.6 wt%, with the double occupancy in the small cage and quintuple occupancy in the large cage. Molecular dynamics simulations indicate that these multiple occupied hydrogen hydrates can occur at mild conditions, and their stability will be further enhanced by increasing the pressure or decreasing the temperature. Our work highlights that the hydrate is a promising material for storing hydrogen.
Brush-Arm Star Polymer Imaging Agents And Uses Thereof, Jeremiah A. Johnson, Hung Vanthanh Nguyen, Andrzej Rajca
Brush-Arm Star Polymer Imaging Agents And Uses Thereof, Jeremiah A. Johnson, Hung Vanthanh Nguyen, Andrzej Rajca
Chemistry Department: Faculty Publications
Disclosed are methods, compositions, reagents, systems, and kits to prepare nitroxide-functionalized brush-arm star polymer organic radical contrast agent (BASP-ORCA) as well as compositions and uses thereof. Various embodiments show that BASP-ORCA display unprecedented per-nitrox-ide and per-molecule transverse relaxivities for organic radical contrast agents, exceptional stability, high water solubility, low in vitro and in vivo toxicity, and long blood compartment half-life. These materials have the potential to be adopted for tumor imaging using clinical high-field 1H MRI techniques.
Nmr Metabolomics Protocols For Drug Discovery, Fatema Bhinderwala, Robert Powers
Nmr Metabolomics Protocols For Drug Discovery, Fatema Bhinderwala, Robert Powers
Chemistry Department: Faculty Publications
Drug discovery is an extremely difficult and challenging endeavor with a very high failure rate. The task of identifying a drug that is safe, selective and effective is a daunting proposition because disease biology is complex and highly variable across patients. Metabolomics enables the discovery of disease biomarkers, which provides insights into the molecular and metabolic basis of disease and may be used to assess treatment prognosis and outcome. In this regard, metabolomics has evolved to become an important component of the drug discovery process to resolve efficacy and toxicity issues, and as a tool for precision medicine. A detailed …
Reversible Mechanical Deformations Of Soft Microchannel Networks For Sensing In Soft Robotic Systems, Abhiteja Konda, Donghee Lee, Taesun You, Xiaoyan Wang, Sangjin Ryu, Stephen Morin
Reversible Mechanical Deformations Of Soft Microchannel Networks For Sensing In Soft Robotic Systems, Abhiteja Konda, Donghee Lee, Taesun You, Xiaoyan Wang, Sangjin Ryu, Stephen Morin
Chemistry Department: Faculty Publications
Microfluidics has enabled numerous applications in, for example, analytical chemistry, medical diagnostics, microelectronics, and soft robotics. In most of these applications, the geometries of the microchannels are of fixed dimensions that (ideally) remain invariant during operation. In soft robotics, however, the geometries of the microchannels contained in soft actuation systems are inherently dynamic, and the specific dimensions are expected to change during operation, and, by extension, the fluid transport properties of the system are variable. If this characteristic is not properly considered, or if methods are not developed to control it, the progress of soft robotic devices with distributed fluid …
Design Of Single-Molecule Multiferroics For Efficient Ultrahigh-Density Nonvolatile Memories, Qing Yang, Tingting Zhong, Zhengyuan Tu, Lin Zhu, Menghao Wu, Xiao Cheng Zeng
Design Of Single-Molecule Multiferroics For Efficient Ultrahigh-Density Nonvolatile Memories, Qing Yang, Tingting Zhong, Zhengyuan Tu, Lin Zhu, Menghao Wu, Xiao Cheng Zeng
Chemistry Department: Faculty Publications
It is known that an isolated single-molecule magnet tends to become super- paramagnetic even at an ultralow temperature of a few Kelvin due to the low spin switching barrier. Herein, single-molecule ferroelectrics/multiferroics is proposed, as the ultimate size limit of memory, such that every molecule can store 1 bit data. The primary strategy is to identify polar molecules that possess bistable states, moderate switching barriers, and polarizations fixed along the vertical direction for high-density perpendicular recording. First- principles computation shows that several selected magnetic metal porphyrin molecules possess buckled structures with switchable vertical polarizations that are robust at ambient conditions. …
Growth Of Carbon Dioxide Whiskers, Avinash Kumar Both, Chin Li Cheung
Growth Of Carbon Dioxide Whiskers, Avinash Kumar Both, Chin Li Cheung
Chemistry Department: Faculty Publications
We report the growth of carbon dioxide (CO2) whiskers at low temperatures (–70 °C to –65 °C) and moderate pressure (4.4 to 1.0 bar). Their axial growth was assessed by optical video analysis. The identities of these whiskers were confirmed as CO2 solids by Raman spectroscopy. A vapor– solid growth mechanism was proposed based on the influence of the relative humidity on the growth.
Urease Is An Essential Component Of The Acid Response Network Of Staphylococcus Aureus And Is Required For A Persistent Murine Kidney Infection, Chunyi Zhou, Fatema Bhinderwala, Mckenzie K. Lehman, Vinai C. Thomas, Sujata S. Chaudhari, Kelsey J. Yamada, Kirk W. Foster, Robert Powers, Tammy Kielian, Paul D. Fey
Urease Is An Essential Component Of The Acid Response Network Of Staphylococcus Aureus And Is Required For A Persistent Murine Kidney Infection, Chunyi Zhou, Fatema Bhinderwala, Mckenzie K. Lehman, Vinai C. Thomas, Sujata S. Chaudhari, Kelsey J. Yamada, Kirk W. Foster, Robert Powers, Tammy Kielian, Paul D. Fey
Chemistry Department: Faculty Publications
Staphylococcus aureus causes acute and chronic infections resulting in significant morbidity. Urease, an enzyme that generates NH3 and CO2 from urea, is key to pH homeostasis in bacterial pathogens under acidic stress and nitrogen limitation. However, the function of urease in S. aureus niche colonization and nitrogen metabolism has not been extensively studied. We discovered that urease is essential for pH homeostasis and viability in urea-rich environments under weak acid stress. The regulation of urease transcription by CcpA, Agr, and CodY was identified in this study, implying a complex network that controls urease expression in response to changes …
Electrocaloric Effect In Ferroelectric Ceramics With Point Defects, Ming Wu, Qingshan Zhu, Jianting Li, Dongsheng Song, Honghui Wu, Mengyao Guo, Jinghui Gao, Yang Bai, Yujun Feng, Stephen J. Pennycoock, Xiaojie Lou
Electrocaloric Effect In Ferroelectric Ceramics With Point Defects, Ming Wu, Qingshan Zhu, Jianting Li, Dongsheng Song, Honghui Wu, Mengyao Guo, Jinghui Gao, Yang Bai, Yujun Feng, Stephen J. Pennycoock, Xiaojie Lou
Chemistry Department: Faculty Publications
The electrocaloric effect has drawn much attention due to its potential application in cooling devices. A negative electrocaloric effect is predicted to be induced in defect-doped ferroelectrics by computational results [A. Grunebohm and T. Nishimatsu, Phys. Rev. B 93, 134101 (2016) and Ma et al., Phys. Rev. B 94, 094113 (2016)], but it need to be confirmed by experimental results. In this work, we prepared a 1mol. % Mn-doped Pb(Zr0.2,Ti0.8)O3 ceramics (Pb((Zr0.2,Ti0.8)0.99,Mn0.01)O3), and the electrocaloric effect of the defect-containing ferroelectric ceramics has …
Role Of Water On The Rotational Dynamics Of The Organic Methylammonium Cation: A First Principles Analysis, Ross D. Hoehn, Joseph S. Francisco, Sabre Kais, Ali Kachmar
Role Of Water On The Rotational Dynamics Of The Organic Methylammonium Cation: A First Principles Analysis, Ross D. Hoehn, Joseph S. Francisco, Sabre Kais, Ali Kachmar
Chemistry Department: Faculty Publications
Understanding the degradation mechanisms of lead-halide perovskites (CH3NH3PbI3) under exposure to liquid/aerosol water is an essential problem within the photovoltaic community. Herein we investigate both the static and the dynamic properties of the methylammonuim cation (MA) as it coordinates with invading water molecules (MA.(H2O)n, n = 1, 2, 3, 4) using both stationary state quantum mechanics and first principle molecular dynamics simulations. Various solvation structures of MA were characterized by their stabilization energies, dipoles, and Maximally-Localized Wannier Function (MLWF) centers. Calculation – and analysis – of vibrational shifts in the …
The Inductive Effect In Organic Chemistry, Charles A. Kingsbury
The Inductive Effect In Organic Chemistry, Charles A. Kingsbury
Chemistry Department: Faculty Publications
The subtle difference between the successive polarization model and the flow of electrons through sigma bonds is explored, as well as the alternating charge model of Pople and the pervasive field model. The present paper is concerned with the ability of alkyl groups to serve as sigma inductive electron donors.