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Articles 6481 - 6510 of 33166

Full-Text Articles in Chemistry

Synthesis And Characterization Of Cellulose Acetate Membrane From Cotton Spinning Waste, Silvy Djayanti, Syarifa Arum Kusumastuti, Januar Fatkhurrahman, Agus Purwanto, Agung Budiarto, Alex Lukmanto Suherman Sep 2021

Synthesis And Characterization Of Cellulose Acetate Membrane From Cotton Spinning Waste, Silvy Djayanti, Syarifa Arum Kusumastuti, Januar Fatkhurrahman, Agus Purwanto, Agung Budiarto, Alex Lukmanto Suherman

Makara Journal of Science

Cellulose acetate membrane (CAM) was successfully synthesized and characterized from the cotton spinning waste of the textile industry. The membrane was produced through the isolation, acetylation, and phase inversion stages. The highest yields of cellulose fiber and α-cellulose contents were obtained using 3.0% and 6.0% v/v NaClO, respectively. The C–O acetyl bond detected by Fourier Transform Infrared (FTIR) analysis indicates the formation of the CAM. The resulting membrane can be potentially applied as an ultrafiltration membrane for water desalination purposes in water and wastewater treatment facilities. Furthermore, the utilization of cotton spinning waste as raw material aims to produce inexpensive …

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Synthesis And Complexation Of Monotosylated 4-Aminopyridine With Nickel (Ii) And Iron (Ii) Ions, Kingsley John Orie, Remy Ukachukwu Duru, Raphael I-Oro Ngochindo Sep 2021

Synthesis And Complexation Of Monotosylated 4-Aminopyridine With Nickel (Ii) And Iron (Ii) Ions, Kingsley John Orie, Remy Ukachukwu Duru, Raphael I-Oro Ngochindo

Makara Journal of Science

Tosylated 4-aminopyridine and other sulfonylated compounds of amines comprise a substantial class of pharmaceutical drugs used as antibiotics in the field of medicine. This research aimed at the synthesis of tosylated 4-aminopyridine and the complexation of the tosyated 4-aminopyridine with Ni(II) and Fe(II) ions. The sulfonamide was prepared by the action of tosyl chloride on 4-aminopyridine in an aqueous alkaline medium. The complexes were synthesized by the reaction of Ni(NO3)2.6H2O /Fe(NO3)2.6H2O with sulfonamide derivative. These compounds were characterized through Ultraviolet Visible spectroscopy (UV–Vis), Fourier Transform Infer-Red (FTIR) spectroscopy, …

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Characterization Of A Nitro-Forming Enzyme Involved In Fosfazinomycin Biosynthesis, Hannah Valentino, Pablo Sobrado Sep 2021

Characterization Of A Nitro-Forming Enzyme Involved In Fosfazinomycin Biosynthesis, Hannah Valentino, Pablo Sobrado

Chemistry Faculty Research & Creative Works

N-hydroxylating monooxygenases (NMOs) are a subclass of flavin-dependent enzymes that hydroxylate nitrogen atoms. Recently, unique NMOs that perform multiple reactions on one substrate molecule have been identified. Fosfazinomycin M (FzmM) is one such NMO, forming nitrosuccinate from aspartate (Asp) in the fosfazinomycin biosynthetic pathway in someStreptomycessp. This work details the biochemical and kinetic analysis of FzmM. Steady-state kinetic investigation shows that FzmM performs a coupled reaction with Asp (kcat, 3.0 ± 0.01 s-1) forming nitrosuccinate, which can be converted to fumarate and nitrite by the action of FzmL. FzmM displays a 70-fold higherkcat/KMvalue for NADPH compared to NADH and has …

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Oxidation Alters The Architecture Of The Phenylalanyl-Trna Synthetase Editing Domain To Confer Hyperaccuracy, Pooja Srinivas, Rebecca E. Steiner, Ian J. Pavelich, Ricardo Guerrera-Ferreira, Puneet Juneja, Michael Ibba, Christine M. Dunham Sep 2021

Oxidation Alters The Architecture Of The Phenylalanyl-Trna Synthetase Editing Domain To Confer Hyperaccuracy, Pooja Srinivas, Rebecca E. Steiner, Ian J. Pavelich, Ricardo Guerrera-Ferreira, Puneet Juneja, Michael Ibba, Christine M. Dunham

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

High fidelity during protein synthesis is accomplished by aminoacyl-tRNA synthetases (aaRSs). These enzymes ligate an amino acid to a cognate tRNA and have proofreading and editing capabilities that ensure high fidelity. Phenylalanyl-tRNA synthetase (PheRS) preferentially ligates a phenylalanine to a tRNAPhe over the chemically similar tyrosine, which differs from phenylalanine by a single hydroxyl group. In bacteria that undergo exposure to oxidative stress such as Salmonella enterica serovar Typhimurium, tyrosine isomer levels increase due to phenylalanine oxidation. Several residues are oxidized in PheRS and contribute to hyperactive editing, including against mischarged Tyr-tRNAPhe, despite these oxidized residues not …

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Effects Of Fluoride On Submandibular Glands Of Mice: Changes In Oxidative Biochemistry, Proteomic Profile, And Genotoxicity, Leidiane Alencar De Oliveira Lima, Giza Hellen Nonato Miranda, Walessa Alana Bragança Aragão, Leonardo Oliveira Bittencourt, Sávio Monteiro Dos Santos, Michel Platini Caldas De Souza, Lygia S. Nogueira, Edivaldo Herculano Corrêa De Oliveira, Marta Chagas Monteiro, Aline Dionizio, Aline Lima Leite, Juliano Pelim Pessan, Marília Afonso Rabelo Buzalaf, Rafael Rodrigues Lima Sep 2021

Effects Of Fluoride On Submandibular Glands Of Mice: Changes In Oxidative Biochemistry, Proteomic Profile, And Genotoxicity, Leidiane Alencar De Oliveira Lima, Giza Hellen Nonato Miranda, Walessa Alana Bragança Aragão, Leonardo Oliveira Bittencourt, Sávio Monteiro Dos Santos, Michel Platini Caldas De Souza, Lygia S. Nogueira, Edivaldo Herculano Corrêa De Oliveira, Marta Chagas Monteiro, Aline Dionizio, Aline Lima Leite, Juliano Pelim Pessan, Marília Afonso Rabelo Buzalaf, Rafael Rodrigues Lima

Department of Chemistry: Faculty Publications

Although fluoride (F) is well-known to prevent dental caries, changes in cell processes in different tissues have been associated with its excessive exposure. Thus, this study aimed to evaluate the effects of F exposure on biochemical, proteomic, and genotoxic parameters of submandibular glands. Twenty one old rats (n = 30) were allocated into three groups: 60 days administration of drinking water containing 10 mgF/L, 50 mgF/L, or only deionized water (control). The submandibular glands were collected for oxidative biochemistry, protein expression profile, and genotoxic potential analyses. The results showed that both F concentrations increased the levels of thiobarbituric acid–reactive …

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Atomistic Simulations And In Silico Mutational Profiling Of Protein Stability And Binding In The Sars-Cov-2 Spike Protein Complexes With Nanobodies: Molecular Determinants Of Mutational Escape Mechanisms, Gennady M. Verkhivker, Steve Agajanian, Deniz Yasar Oztas, Grace Gupta Sep 2021

Atomistic Simulations And In Silico Mutational Profiling Of Protein Stability And Binding In The Sars-Cov-2 Spike Protein Complexes With Nanobodies: Molecular Determinants Of Mutational Escape Mechanisms, Gennady M. Verkhivker, Steve Agajanian, Deniz Yasar Oztas, Grace Gupta

Mathematics, Physics, and Computer Science Faculty Articles and Research

Structure-functional studies have recently revealed a spectrum of diverse high-affinity nanobodies with efficient neutralizing capacity against SARS-CoV-2 virus and resilience against mutational escape. In this study, we combine atomistic simulations with the ensemble-based mutational profiling of binding for the SARS-CoV-2 S-RBD complexes with a wide range of nanobodies to identify dynamic and binding affinity fingerprints and characterize the energetic determinants of nanobody-escaping mutations. Using an in silico mutational profiling approach for probing the protein stability and binding, we examine dynamics and energetics of the SARS-CoV-2 complexes with single nanobodies Nb6 and Nb20, VHH E, a pair combination VHH E + …

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Controlling Degradation With Force And Light, Brad Davis Sep 2021

Controlling Degradation With Force And Light, Brad Davis

Dissertations

Stimuli-responsive polymers respond to changes in their environment by altering their physical and chemical properties. Their responsiveness allows them to be used as sensors, mechanical actuators, delivery systems, and can yield either elongated lifetimes through healing mechanisms or shortened lifetimes through triggered degradation. Still a growing field in polymer science, researchers seek to expand the capabilities of these materials by improving their specificity, range, and mechanisms of both the stimuli and the response. The work presented explores stimuli-responsive materials, focusing on mechanical and light stimuli, and how to gain control of the response by specific changes in the polymeric material. …

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Metal-Free Domino Amination-Knoevenagel Condensation Approach To Access New Coumarins As Potent Nanomolar Inhibitors Of Vegfr-2 And Egfr, Essam M. Eliwa, Marcel Frese, Ahmed H. Halawa, Maha M. Soltan, Larissa V. Ponomareva, Jon S. Thorson, Khaled A. Shaaban, Mohamed Shaaban, Ahmed M. El-Agrody, Norbert Sewald Sep 2021

Metal-Free Domino Amination-Knoevenagel Condensation Approach To Access New Coumarins As Potent Nanomolar Inhibitors Of Vegfr-2 And Egfr, Essam M. Eliwa, Marcel Frese, Ahmed H. Halawa, Maha M. Soltan, Larissa V. Ponomareva, Jon S. Thorson, Khaled A. Shaaban, Mohamed Shaaban, Ahmed M. El-Agrody, Norbert Sewald

Center for Pharmaceutical Research and Innovation Faculty Publications

A metal-free, atom-economy and simple work-up domino amination-Knoevenagel condensation approach to construct new coumarin analogous (4a-f and 8a-e) was described. Further, new formyl (5a,d-f) and nitro (9a,d-f) coumarin derivatives were synthesized via C-N coupling reaction of various cyclic secondary amines and 4-chloro-3-(formyl-/nitro)coumarins (1a,c), respectively. The confirmed compounds were screened for their in vitro anti-proliferative activity against KB-3-1, A549 and PC3 human cancer cell lines using resazurin cellular-based assay. Among them, coumarin derivatives 4e and 8e displayed the best anti-cervical cancer potency (KB-3-1) with IC50 values of 15.5 ± 3.54 …

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Two-Dimensional Monolayer Salt Nanostructures Can Spontaneously Aggregate Rather Than Dissolve In Dilute Aqueous Solutions, Wenhui Zhao, Yunxiang Sun, Weiduo Zhu, Jian Jiang, Xiaorong Zhao, Dongdong Lin, Wenwu Xu, Xiangmei Duan, Joseph S. Francisco, Xiao Cheng Zeng Sep 2021

Two-Dimensional Monolayer Salt Nanostructures Can Spontaneously Aggregate Rather Than Dissolve In Dilute Aqueous Solutions, Wenhui Zhao, Yunxiang Sun, Weiduo Zhu, Jian Jiang, Xiaorong Zhao, Dongdong Lin, Wenwu Xu, Xiangmei Duan, Joseph S. Francisco, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

It is well known that NaCl salt crystals can easily dissolve in dilute aqueous solutions at room temperature. Herein, we reported the first computational evidence of a novel salt nucleation behavior at room temperature, i.e., the spontaneous formation of two-dimensional (2D) alkali chloride crystalline/non-crystalline nanostructures in dilute aqueous solution under nanoscale confinement. Microsecond-scale classical molecular dynamics (MD) simulations showed that NaCl or LiCl, initially fully dissolved in confined water, can spontaneously nucleate into 2D monolayer nanostructures with either ordered or disordered morphologies. Notably, the NaCl nanostructures exhibited a 2D crystalline square-unit pattern, whereas the LiCl nanostructures adopted non-crystalline 2D hexagonal …

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A Compendium Of Inorganic Photochemistry: Synthetic And Spectroscopic Discoveries, Sebastian B. Vittardi Sep 2021

A Compendium Of Inorganic Photochemistry: Synthetic And Spectroscopic Discoveries, Sebastian B. Vittardi

Chemistry and Chemical Biology ETDs

This dissertation reports and examines contributions made in the advancement of inorganic photochemistry. Empirically driven assessments are allotted to the interplay between ligand sets, excited states, and photochemistry observed in metal complexes. A methodical spectroscopic examination is provided for oligothiophene-sensitized lanthanides. Their excited state dynamics were elucidated by femtosecond pump-probe spectroscopy and used to develop a model explaining their wavelength-dependent dual functionality. Iron (II) cyanide and isocyanides are evaluated to identify the efficacy of strong-field ligands in promoting charge-transfer excited states. Fundamentals of ligand field theory helped conceptualize the synthetically tunable parameters and effects transposed to their absorption dynamics. Transition …

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Neuron-Derived Extracellular Vesicles Modulate Microglia Activation And Function, Hui Peng, Brock T. Harvey, Christopher I. Richards, Kimberly Nixon Sep 2021

Neuron-Derived Extracellular Vesicles Modulate Microglia Activation And Function, Hui Peng, Brock T. Harvey, Christopher I. Richards, Kimberly Nixon

Pharmaceutical Sciences Faculty Publications

Microglia act as the immune cells of the central nervous system (CNS). They play an important role in maintaining brain homeostasis but also in mediating neuroimmune responses to insult. The interactions between neurons and microglia represent a key process for neuroimmune regulation and subsequent effects on CNS integrity. However, the molecular mechanisms of neuron-glia communication in regulating microglia function are not fully understood. One recently described means of this intercellular communication is via nano-sized extracellular vesicles (EVs) that transfer a large diversity of molecules between neurons and microglia, such as proteins, lipids, and nucleic acids. To determine the effects of …

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Vermiculations In Painted Caves: New Inputs From Laboratory Experiments And Field Observations, Perrine Freydier, Eric Weber, Jérôme Martin, Pierre-Yves Jeannin, Béatrice Guerrier, Frédéric Doumenc Sep 2021

Vermiculations In Painted Caves: New Inputs From Laboratory Experiments And Field Observations, Perrine Freydier, Eric Weber, Jérôme Martin, Pierre-Yves Jeannin, Béatrice Guerrier, Frédéric Doumenc

International Journal of Speleology

Vermiculations are aggregates of small particles commonly found on cave walls. They are a major concern for the conservation of painted caves, as they can potentially alter valuable prehistoric cave paintings. A previous rheological study of fine sediment deposits on cave walls revealed that this material can undergo a solid-to-liquid transition triggered by variations in the chemical composition of the water film on the wall. Such a transition could occur at the origin of vermiculations by allowing the sediment to flow under low mechanical stress. In this work, we provide quantitative information on the conditions leading to this transition and …

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Atomistic Insights Into The Formation Of Nonspecific Protein Complexes During Electrospray Ionization., Elnaz Aliyari, Lars Konermann Sep 2021

Atomistic Insights Into The Formation Of Nonspecific Protein Complexes During Electrospray Ionization., Elnaz Aliyari, Lars Konermann

Chemistry Publications

Native electrospray ionization (ESI)-mass spectrometry (MS) is widely used for the detection and characterization of multi-protein complexes. A well-known problem with this approach is the possible occurrence of nonspecific protein clustering in the ESI plume. This effect can distort the results of binding affinity measurements, and it can even generate gas-phase complexes from proteins that are strictly monomeric in bulk solution. By combining experiments and molecular dynamics (MD) simulations, the current work for the first time provides detailed insights into the ESI clustering of proteins. Using ubiquitin as a model system, we demonstrate how the entrapment of more than one …

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Molecular And Supramolecular Structures Of Triiodides And Polyiodobismuthates Of Phenylenediammonium And Its N,N-Dimethyl Derivative, Evgeny V. Dikarev, Zheng Wei, Tatiana A. Shestimerova, Nikita A. Golubev, Mikhail A. Bykov, Andrei V. Mironov, Sergey A. Fateev, Alexey B. Tarasov, Ivan Turkevych, Andrei V. Shevelkov Sep 2021

Molecular And Supramolecular Structures Of Triiodides And Polyiodobismuthates Of Phenylenediammonium And Its N,N-Dimethyl Derivative, Evgeny V. Dikarev, Zheng Wei, Tatiana A. Shestimerova, Nikita A. Golubev, Mikhail A. Bykov, Andrei V. Mironov, Sergey A. Fateev, Alexey B. Tarasov, Ivan Turkevych, Andrei V. Shevelkov

Chemistry Department Faculty Scholarship

Despite remarkable progress in photoconversion efficiency, the toxicity of lead-based hybrid perovskites remains an important issue hindering their applications in consumer optoelectronic devices, such as solar cells, LED displays, and photodetectors. For that reason, lead-free metal halide complexes have attracted great attention as alternative optoelectronic materials. In this work, we demonstrate that reactions of two aromatic diamines with iodine in hydroiodic acid produced phenylenediammonium (PDA) and N,N-dimethyl-phenylenediammonium (DMPDA) triiodides, PDA(I3)2⋅2H2O and DMPDA(I3)I, respectively. If the source of bismuth was added, they were converted into previously reported PDA(BiI4)2⋅I2 …

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Mitochondrial Proteins In Mediating Colon Cancer And Potential Theraputics, Kunlun Yin Sep 2021

Mitochondrial Proteins In Mediating Colon Cancer And Potential Theraputics, Kunlun Yin

Chemistry and Chemical Biology ETDs

Cancer is one of the biggest threatens to human health. Many people died because of various types of cancer. Colon cancer is one of the leading causes of new incidence and mortality in the whole world. It is important to understand the mechanism of tumorigenesis and development. Based on the mechanisms, we may develop new therapeutics to improve survival rate. In Chapter 2, we discussed the PINK1 function in suppression colon cancer. We found that PINK1 deficiency can promote colon cancer, and PINK1 overexpression suppressed tumor growth in vivo and in vitro. PINK1 can activate its substrate P53, which activates …

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Labeling And Characterization Of Exosomes To Elucidate Their Cellular Uptake Within Tumor And Stromal Cells, Rabab Hamzah Sep 2021

Labeling And Characterization Of Exosomes To Elucidate Their Cellular Uptake Within Tumor And Stromal Cells, Rabab Hamzah

Theses and Dissertations

Exosomes are natural nanoparticles released by all eukaryotic cells studied thus far and a wide range of different biological fluids. Their components are derived from parent cells and can be transferred to other cell types and locations in an organism which makes exosome a promising nanosized-agent to treat and diagnose various diseases. Several research studies have been done to load exosomes with drugs and nucleic acids to develop a number of new therapeutic nano-vehicle. A few research studies have been done to combine these natural nanoparticles (exosomes) and artificial nanoparticles to develop a new theranostic nano-agent. In this research, we …

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Novel Pilot Development Of A Closed-Loop Sustainable System Between Biogas Renewable Energy, Distilling, And Aquaculture By Vermiculture Of Stillage Wastes, Samuel C. Kessler Sep 2021

Novel Pilot Development Of A Closed-Loop Sustainable System Between Biogas Renewable Energy, Distilling, And Aquaculture By Vermiculture Of Stillage Wastes, Samuel C. Kessler

The Cardinal Edge

This study provides a mixed-methods approach in analyzing a potential closed-loop system between renewable biogas production from anaerobic digestion, vermiculture production, aquaculture production, and organic wastes with a particular focus on stillage wastes. Such system may hold significant promise for significantly reducing organic carbon and methane emissions from its components, and should be assessed for such. The 2021 IPCC report essentially identified methane reduction as the single fastest way to slow global warming (IPCC, 2021), making the study and implementation of methane-reducing systems and supportive policy for them critical. Knowledge gaps to implementing this system were qualitatively identified as disconnect …

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Selenium Probes For The Detection Of Thioredoxin Reductase Activity, Tendai Joseph Mafireyi Sep 2021

Selenium Probes For The Detection Of Thioredoxin Reductase Activity, Tendai Joseph Mafireyi

Dissertations and Theses

The identification and quantification of proteins and enzymatic activity in living tissues frequently requires the use of invasive procedures such as biopsy. These techniques can inhibit measurements of protein levels in real-time, and the disruption of tissue can lead to the loss of important information concerning the spatial distribution and differential activities in various cell types. The use of small organic fluorescent probes that rely on activation or accumulation within a tissue embody robust methods of detection that address these issues. This dissertation describes the design, synthesis and evaluation of fluorescent probes that can detect the enzyme thioredoxin reductase (TrxR). …

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Does A Bottom-Up Mechanism Promote Hypoxia In The Mississippi Bight?, Virginie Sanial, Willard S. Moore, Alan M. Shiller Sep 2021

Does A Bottom-Up Mechanism Promote Hypoxia In The Mississippi Bight?, Virginie Sanial, Willard S. Moore, Alan M. Shiller

Faculty Publications

The Mississippi Bight, east of the Mississippi River, is a complex coastal ecosystem that, like the better-known Louisiana Shelf to the west, experiences seasonal bottom water hypoxia. However, input of allochthonous nutrients from the Mississippi River to the Mississippi Bight appears to be limited, begging the question of what drives seasonal hypoxia in this system. Prior research has suggested submarine groundwater discharge (SGD) could be an overlooked component of the Mississippi Bight biogeochemical system. We thus examined the hypothesis that SGD provides a “bottom up” driver for seasonal hypoxia in this area. We used a multi-tracer approach based on known …

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Benzopyrazine-Based Small Molecule Inhibitors As Trypanocidal And Leishmanicidal Agents: Green Synthesis, In Vitro, And In Silico Evaluations, Jonathan Rock, Daniel Garcia, Omar Espino, Shaila A. Shetu, Manuel J. Chan-Bacab, Rosa Moo-Puc, Navin B. Patel, Gildardo Rivera, Debasish Bandyopadhyay Sep 2021

Benzopyrazine-Based Small Molecule Inhibitors As Trypanocidal And Leishmanicidal Agents: Green Synthesis, In Vitro, And In Silico Evaluations, Jonathan Rock, Daniel Garcia, Omar Espino, Shaila A. Shetu, Manuel J. Chan-Bacab, Rosa Moo-Puc, Navin B. Patel, Gildardo Rivera, Debasish Bandyopadhyay

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

World Health Organization (WHO) identified twenty tropical disease categories as neglected tropical diseases (NTDs)1. Chagas’ disease (also known as American trypanosomiasis) and leishmaniasis are two major classes of NTDs. The total number of mortality, morbidity, and disability attributed each year due to these two categories of diseases in magnitudes is much higher than the so-called elite diseases like cancer, diabetes, AIDS, cardiovascular and neurodegenerative diseases. Impoverished communities around the world are the major victim of NTDs. The development of new and novel drugs in the battle against Chagas’ disease and leishmaniasis is highly anticipated. An easy and straightforward …

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Inelastic, Exchange, And Reactive Processes In Rovibrationally Excited Collisions Of Hd With H, Boyi Zhou, Benhui Yang, Balakrishnan Naduvalath, B. K. Kendrick, Maodu Chen, P. C. Stancil Sep 2021

Inelastic, Exchange, And Reactive Processes In Rovibrationally Excited Collisions Of Hd With H, Boyi Zhou, Benhui Yang, Balakrishnan Naduvalath, B. K. Kendrick, Maodu Chen, P. C. Stancil

Chemistry and Biochemistry Faculty Research

The HD molecule is an important coolant in early universe chemistry models and a tracer of H2 in star-forming regions. Rate coefficients for collisional excitation and de-excitation of HD rotational and vibrational levels form important ingredients in astrophysical models. While collisions with He, H2, and H are the most important, available data for H + HD collisions are largely limited to temperatures less than 1000 K for the vibrational ground state, low-lying rotational levels of the v = 1 HD vibrational level, or computed without reactive contributions. Here, through explicit quantum scattering calculations, we report extensive data for rovibrational transitions …

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Small Studies, Big Decisions: The Role Of Pilot/Feasibility Studies In Incremental Science And Premature Scale-Up Of Behavioral Interventions, Michael William Beets, Lauren Von Klinggraeff, Robert G. Weaver, Bridget Ryan Armstrong, Sarah Burkart Sep 2021

Small Studies, Big Decisions: The Role Of Pilot/Feasibility Studies In Incremental Science And Premature Scale-Up Of Behavioral Interventions, Michael William Beets, Lauren Von Klinggraeff, Robert G. Weaver, Bridget Ryan Armstrong, Sarah Burkart

Faculty Publications

Background: Careful consideration and planning are required to establish “sufficient” evidence to ensure an investment in a larger, more well-powered behavioral intervention trial is worthwhile. In the behavioral sciences, this process typically occurs where smaller-scale studies inform larger-scale trials. Believing that one can do the same things and expect the same outcomes in a larger-scale trial that were done in a smaller-scale preliminary study (i.e., pilot/feasibility) is wishful thinking, yet common practice. Starting small makes sense, but small studies come with big decisions that can influence the usefulness of the evidence designed to inform decisions about moving forward with a …

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Emergence Of Non-Hexagonal Crystal Packing Of Deswollen And Deformed Ultra-Soft Microgels Under Osmotic Pressure Control, Molla R. Islam, Rachel Nguyen, L. Andrew Lyon Sep 2021

Emergence Of Non-Hexagonal Crystal Packing Of Deswollen And Deformed Ultra-Soft Microgels Under Osmotic Pressure Control, Molla R. Islam, Rachel Nguyen, L. Andrew Lyon

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Highly solvent swollen poly(N-isopropylacrylamide-co-acrylic acid) microgels are synthesized without exogenous crosslinker, making them extremely soft and deformable. These ultralow crosslinked microgels (ULC) are incubated under controlled osmotic pressure to provide a slow (and presumably thermodynamically controlled) approach to higher packing densities. It is found that ULC microgels show stable colloidal packing over a very wide range of osmotic pressures and thus packing densities. Surprising observation of co-existence between hexagonal and square lattices is also made over the lower range of studied osmotic pressures, with microgels apparently changing shape from spheres to cubes in defects or grain boundaries. It is proposed …

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Analysis Of The Electronic Effects And Reactivity Of Benzhydrols In The Formation Of Benzhydryl Ethers, Katherine Quesada, Daniel Chabeda, Jaeger Johnson, Alex Shore Sep 2021

Analysis Of The Electronic Effects And Reactivity Of Benzhydrols In The Formation Of Benzhydryl Ethers, Katherine Quesada, Daniel Chabeda, Jaeger Johnson, Alex Shore

The Yale Undergraduate Research Journal

Benzhydryl ethers were synthesized through the use of microwave irradiation in a proto-ionic liquid solvent. The resulting products were separated from the reaction mixture by vacuum filtration with a silica gel plug. The products were analyzed using GCMS and 1 H NMR techniques to identify and quantify products. Analysis of the resultant data indicated the syntheses of the desired benzhydryl products were successful for 4,4-dimethoxybenzhydrol (conversion: 83% (1-propyl ether), 11% (2-propyl ether), 11% (menthyl ether)) and 4,4-dimethylbenzhydrol (conversion to desired product: 100% (1-propyl ether), 100% (2-propyl ether), 26% (menthyl ether)). However, the syntheses were unsuccessful for reactant 4,4-difluorobenzhydrol and benzhydrol. …

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Spectral Analysis Of A New Electronic Transition Of Platinum Fluoride, Ptf, Carol Welch Sep 2021

Spectral Analysis Of A New Electronic Transition Of Platinum Fluoride, Ptf, Carol Welch

Undergraduate Research Symposium

The electronic landscape of platinum containing molecules has been the focus of numerous spectroscopic studies in recent years, because of the difficulty in describing electronic structure theoretically due to electronic correlations and relativistic effects. A collective effort by spectroscopitsts and theoreticians to investigate the diatomic molecule platinum fluoride, PtF, has included research such as developing potential energy diagrams and performing analyses on rotational transitions with microwave spectroscopy. One group observed electronic transitions of PtF using laser vaporization/reaction with jet free expansion and laser induced spectroscopy. A highly effective method for observing and analyzing electronic transitions of small, metal-containing molecules like …

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Pressure-Induced Polymorphic Transformations Of Ethylenediamine Bisborane, Rongfeng Guan, Pan Wang, Yang Song, Viktor N. Staroverov Sep 2021

Pressure-Induced Polymorphic Transformations Of Ethylenediamine Bisborane, Rongfeng Guan, Pan Wang, Yang Song, Viktor N. Staroverov

Chemistry Publications

Pressure-induced phase transitions of crystalline ethylenediamine bisborane (EDAB), a prospective hydrogen storage material, are investigated using vibrational spectroscopy, X-ray diffraction, evolutionary crystal structure prediction, and density functional theory. The results indicate that EDAB undergoes two transitions in the 0–17 GPa pressure range: the first one is near 1 GPa, from the orthorhombic ambient-pressure Pbca structure (phase I) to a monoclinic structure of P21/c symmetry (phase II); the second is near 7 GPa, from phase II to another P21/c structure (phase III). The latter coexists with phase II and remains the most stable form of EDAB up …

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An Examination Of Factors Influencing Small Proton Chemical Shift Differences In Nitrogen-Substituted Monodeuterated Methyl Groups, Stuart J. Elliott, O. Maduka Ogba, Lynda J. Brown, Daniel J. O'Leary Sep 2021

An Examination Of Factors Influencing Small Proton Chemical Shift Differences In Nitrogen-Substituted Monodeuterated Methyl Groups, Stuart J. Elliott, O. Maduka Ogba, Lynda J. Brown, Daniel J. O'Leary

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Monodeuterated methyl groups have previously been demonstrated to provide access to long-lived nuclear spin states. This is possible when the CH2 D rotamers have sufficiently different populations and the local environment is chiral, which foments a non-negligible isotropic chemical shift difference between the two CH2 D protons. In this article, the focus is on the N-CH2 D group of N-CH2 D-2-methylpiperidine and other suitable CH2 D piperidine derivatives. We used a combined experimental and computational approach to investigate how rotameric symmetry breaking leads to a 1H CH2 D chemical shift …

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Systematic And Collaborative Approach To Problem Solving Using X-Ray Photoelectron Spectroscopy, Neal Fairley, Vincent Fernandez, Mireille Richard-Plouet, Catherine Guillot-Deudon, John Walton, Emily Smith, Delphine Flahaut, Mark Greiner, Mark Biesinger, Sven Tougaard, David Morgan, Jonas Baltrusaitis Sep 2021

Systematic And Collaborative Approach To Problem Solving Using X-Ray Photoelectron Spectroscopy, Neal Fairley, Vincent Fernandez, Mireille Richard-Plouet, Catherine Guillot-Deudon, John Walton, Emily Smith, Delphine Flahaut, Mark Greiner, Mark Biesinger, Sven Tougaard, David Morgan, Jonas Baltrusaitis

Chemistry Publications

The methodology presented within this work is a result of years of interactions between many junior and senior X-ray Photoelectron Spectroscopy (XPS) users operating within the CasaXPS spectral processing and interpretation program framework. In particular, discussions arising from a series of workshops have been a significant source for developing the overall XPS data processing concept and are the motivation for creating this work. These workshops organized by the Institut des Matériaux Jean Rouxel (IMN), Nantes gather both experienced and novice users of XPS for a week of discourse in conceptual experiment design and the resulting data processing. However, the framework …

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Bioaccessibility And Reactivity Of Alloy Powders Used In Powder Bed Fusion Additive Manufacturing, Yolanda S. Hedberg Sep 2021

Bioaccessibility And Reactivity Of Alloy Powders Used In Powder Bed Fusion Additive Manufacturing, Yolanda S. Hedberg

Chemistry Publications

Exposure to metal particles via the inhalation route unavoidably takes place at occupational settings during additive manufacturing of metals and alloys. This calls for investigations on possible adverse health effects. This study focuses on virgin and reused powders of three iron- and nickel-based alloy powders (316L, IN718, 18Ni300) widely used in additive manufacturing, and dust powder of 18Ni300 generated during laser melting. Investigations were performed from a physico-chemical and toxicological perspective assessing their bioaccessibility in artificial lysosomal fluid (ALF, simulating lung exposure to respirable particles), corrosion behavior, surface morphology and composition, microstructure, hydrodynamic size distribution in ALF, and in-vitro toxicity …

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Citation Patterns In Chemistry Dissertations At A Mid-Sized University: An Internal Citation Analysis And External Comparison, Lisa M. Rose-Wiles Sep 2021

Citation Patterns In Chemistry Dissertations At A Mid-Sized University: An Internal Citation Analysis And External Comparison, Lisa M. Rose-Wiles

Library Publications

This study analyzes the references cited in 34 chemistry dissertations and compares the results with an earlier study of citations in American Chemical Society journals. The dissertations cite more references and older references and a greater diversity of sources. They have the same tendency to heavily cite journal articles from a small core of traditional journals. This study underscores the value of comparing internal citation analyses with external citation analyses, and of analyzing the number of citing authors as well as the number of citations. Interlibrary loan and internal usage statistics were also used to inform collection development and library …

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