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Articles 721 - 750 of 1129
Full-Text Articles in Chemistry
What Is Wrong With Water Barometers?, Dan Sullivan, Robert W. Smith, E. J. Kemnitz, Kevin Barton, Robert M. Graham, Raymond A. Guenther, Larry Webber
What Is Wrong With Water Barometers?, Dan Sullivan, Robert W. Smith, E. J. Kemnitz, Kevin Barton, Robert M. Graham, Raymond A. Guenther, Larry Webber
Chemistry Faculty Publications
Every student who studies atmospheric pressure in physics or chemistry learns the principles behind the construction of barometers. Cistern barometers, such as those found in most laboratories, consist of a long glass tube containing an inverted column of liquid having an open end in a cistern of the liquid. Students learn that the column of liquid is supported by air pressure and is equal in weight to a column of air of the same diameter.
Pulsed Laser Deposition Of Graphite Counter Electrodes For Dye-Sensitized Solar Cells, Pavel Anzenbacher Jr., Krishna P. Acharya, Himal Khatri, Sylvain Marsillac, Bruno Ullrich, Mikhail Zamkov
Pulsed Laser Deposition Of Graphite Counter Electrodes For Dye-Sensitized Solar Cells, Pavel Anzenbacher Jr., Krishna P. Acharya, Himal Khatri, Sylvain Marsillac, Bruno Ullrich, Mikhail Zamkov
Chemistry Faculty Publications
We report on pulsed laser deposition of graphite onto flexible plastic and conductive glass substrates for use as a counter electrode in dye-sensitized solar cells. The efficiency of as-prepared graphite electrodes was tested using CdS-sensitized solar cell architecture resulting in external quantum efficiency comparable to that of conventional platinum counter electrodes. This work highlights the possibility of using pulsed laser deposited graphite as a low-cost alternative to platinum, which could be fabricated both on flexible and rigid substrates. © 2010 American Institute of Physics.
Energy Barrier, Charge Carrier Balance, And Performance Improvement In Organic Light-Emitting Diodes, Pavel Anzenbacher Jr., Amare Benor, Shin-Ya Takizawa, C. Pérez-Bolivar
Energy Barrier, Charge Carrier Balance, And Performance Improvement In Organic Light-Emitting Diodes, Pavel Anzenbacher Jr., Amare Benor, Shin-Ya Takizawa, C. Pérez-Bolivar
Chemistry Faculty Publications
The charge injection properties of poly(3,4-ethylenedioxythiophene): polystyrene sulfonate anodes are crucial for performance of organic photovoltaics and organic light-emitting diodes (OLEDs). A simple method for tuning hole injection efficiency using UV-ozone is shown to change anode work-function and optimized carriers balance in the devices and improved efficiency in OLEDs. The optimum time of treatment and work-function differs with device architecture. © 2010 American Institute of Physics.
Matrix Isolation And Computational Study Of Isodifluorodibromomethane (F2 Cbr-Br): A Route To Br2 Formation In Cf2 Br2 Photolysis, Alexander N. Tarnovsky, Lisa George, Aimable Kalume, Patrick Z. El-Khoury, Scott A. Reid
Matrix Isolation And Computational Study Of Isodifluorodibromomethane (F2 Cbr-Br): A Route To Br2 Formation In Cf2 Br2 Photolysis, Alexander N. Tarnovsky, Lisa George, Aimable Kalume, Patrick Z. El-Khoury, Scott A. Reid
Chemistry Faculty Publications
The photolysis products of dibromodifluoromethane (CF2 Br 2) were characterized by matrix isolation infrared and UV/Visible spectroscopy, supported by ab initio calculations. Photolysis at wavelengths of 240 and 266 nm of CF2 Br2:Ar samples (∼1:5000) held at ∼5 K yielded iso- CF2 Br2 (F2 CBrBr), a weakly bound isomer of CF2 Br2, which is characterized here for the first time. The observed infrared and UV/Visible absorptions of iso- CF2 Br2 are in excellent agreement with computational predictions at the B3LYP/aug-cc-pVTZ level. Single point energy calculations at the CCSD(T)/aug-cc-pVDZ level on the B3LYP optimized geometries suggest that the isoform is a …
Characterization Of Iso -Cf2 I2 In Frequency And Ultrafast Time Domains, Alexander N. Tarnovsky, Patrick Z. El-Khoury, Lisa George, Aimable Kalume, Scott A. Reid, Bruce S. Ault
Characterization Of Iso -Cf2 I2 In Frequency And Ultrafast Time Domains, Alexander N. Tarnovsky, Patrick Z. El-Khoury, Lisa George, Aimable Kalume, Scott A. Reid, Bruce S. Ault
Chemistry Faculty Publications
The photolysis of diiododifluoromethane (CF2 I2) in condensed phases was studied by a combination of matrix isolation and ultrafast time-resolved spectroscopy, in concert with ab initio calculations. Photolysis at wavelengths of 355 or 266 nm of CF2 I2:Ar samples (1:5000) held at ∼8 K yielded iso -CF2 I2 (F2 C-I-I), a metastable isomer of CF2 I2, characterized here for the first time. The infrared (IR) spectra of this isomer were recorded in matrix experiments, and the derived positions of the C-F stretching modes are in very good agreement with the predictions of high level ab initio calculations, which show that …
8-Methoxy-4-(4-Methoxyphenyl)Quinoline, Pavel Anzenbacher Jr., Ligia Llovera, Teresa González, Simón E. López
8-Methoxy-4-(4-Methoxyphenyl)Quinoline, Pavel Anzenbacher Jr., Ligia Llovera, Teresa González, Simón E. López
Chemistry Faculty Publications
In the title compound, C 17H 15NO 2, the dihedral angle between the quinoline and benzene ring systems is 62.17 (1)°. In the crystal, zigzag chains propagating in c are linked by C-H⋯O hydrogen bonds, and weak C-H⋯π inter-actions link the chains.
Revealing Linear Aggregates Of Light Harvesting Antenna Proteins In Photosynthetic Membranes, Yufan He, Xiaohua Zeng, Saptarshi Mukherjee, Suneth Rajapaksha, Samuel Kaplan, H. Peter Lu
Revealing Linear Aggregates Of Light Harvesting Antenna Proteins In Photosynthetic Membranes, Yufan He, Xiaohua Zeng, Saptarshi Mukherjee, Suneth Rajapaksha, Samuel Kaplan, H. Peter Lu
Chemistry Faculty Publications
How light energy is harvested in a natural photosynthetic membrane through energy transfer is closely related to the stoichiometry and arrangement of light harvesting antenna proteins in the membrane. The specific photosynthetic architecture facilitates a rapid and efficient energy transfer among the light harvesting proteins (LH2 and LH1) and to the reaction center. Here we report the identification of linear aggregates of light harvesting proteins, LH2, in the photosynthetic membranes under ambient conditions by using atomic force microscopy (AFM) imaging and spectroscopic analysis. Our results suggest that the light harvesting protein, LH2, can exist as linear aggregates of 4 2 …
Targeting Base Excision Repair Suggests A New Therapeutic Strategy Of Fludarabine For The Treatment Of Chronic Lymphocytic Leukemia, A. D. Bulgar, M. Snell, J. R. Donze, E. B. Kirkland, Lan Li, Shuming Yang, Yan Xu, S. L. Gerson, Lili Liu
Targeting Base Excision Repair Suggests A New Therapeutic Strategy Of Fludarabine For The Treatment Of Chronic Lymphocytic Leukemia, A. D. Bulgar, M. Snell, J. R. Donze, E. B. Kirkland, Lan Li, Shuming Yang, Yan Xu, S. L. Gerson, Lili Liu
Chemistry Faculty Publications
No abstract provided.
Charge Transfer And Nanostructure Formation During Electroless Etching Of Silicon, Kurt W. Kolasinski
Charge Transfer And Nanostructure Formation During Electroless Etching Of Silicon, Kurt W. Kolasinski
Chemistry Faculty Publications
No abstract provided.
Dynamics Of Porous Silicon Formation By Etching In Hf + V2o5 Solutions, Kurt W. Kolasinski, Justin B. Hartline, Bryan T. Kelly, Julia Yadlovskiy
Dynamics Of Porous Silicon Formation By Etching In Hf + V2o5 Solutions, Kurt W. Kolasinski, Justin B. Hartline, Bryan T. Kelly, Julia Yadlovskiy
Chemistry Faculty Publications
No abstract provided.
A Parallel Non-Alignment Based Approach To Efficient Sequence Comparison Using Longest Common Subsequences, Sanjukta Bhowmick, Mohammad Shafiullah, H. Rai, Dhundy Raj Bastola
A Parallel Non-Alignment Based Approach To Efficient Sequence Comparison Using Longest Common Subsequences, Sanjukta Bhowmick, Mohammad Shafiullah, H. Rai, Dhundy Raj Bastola
Chemistry Faculty Publications
Biological sequence comparison programs have revolutionized the practice of biochemistry, and molecular and evolutionary biology. Pairwise comparison of genomic sequences is a popular method of choice for analyzing genetic sequence data. However the quality of results from most sequence comparison methods are significantly affected by small perturbations in the data and furthermore, there is a dearth of computational tools to compare sequences beyond a certain length. In this paper, we describe a parallel algorithm for comparing genetic sequences using an alignment free-method based on computing the Longest Common Subsequence (LCS) between genetic sequences. We validate the quality of our results …
Controlled Release Ot Methvl Salicvlate In Chitosanpoli[N-Isopropvlacrvlamide] Semi-Interpenetrating Networks, Ma. Assunta C. Cuyegkeng, Terence G. Henares
Controlled Release Ot Methvl Salicvlate In Chitosanpoli[N-Isopropvlacrvlamide] Semi-Interpenetrating Networks, Ma. Assunta C. Cuyegkeng, Terence G. Henares
Chemistry Faculty Publications
A semi-interpenetrating network (semi-IPN) was produced by polymerizing Nisopropylacrylamide (NIP AAm) in the presence of chitosan and cross-linking agent, ethylene glycol dimethacrylate (EGDMA). The resulting material did not swell as much as poly(N-isopropylacrylamide) (piPAAm), but still showed temperature- and pHresponsiveness. Swelling and differential scanning calorimetry (DSC) experiments showed that the lower critical solution temperature (LCST) of the material was at 31 °C. The semiIPN was swollen below 30 °C but started to collapse at this temperature. This is in the same range as the LCST of carrageenan-piPAAm semi-IPN. The chitosan-piPAAm semi-IPN was in a collapsed state and reached maximum swelling …
Extraction Experiments Using Commerciallv Available Spices, Armando M. Guidote Jr, Maricar O. Ribo-Ramos, Dante Gilbert L. De Leon
Extraction Experiments Using Commerciallv Available Spices, Armando M. Guidote Jr, Maricar O. Ribo-Ramos, Dante Gilbert L. De Leon
Chemistry Faculty Publications
Safe and cost-effective experiments were designed for high school students to enhance their laboratory skills and knowledge on polarity and separation of mixtures. Annatto, Spanish paprika and turmeric were extracted yielding red-orange, light red-orange and yellow color, respectively. These were combined with a blue aqueous solution made from food color resulting to green mixtures. These were all extracted with kerosene or oil/kerosene. The non-polar solutes for each mixture combined with the kerosene or oil/kerosene layer, making the polar phase blue again. Students gained a better understanding of the concepts as shown in their laboratory report and test results.
Amino Acid Transport In Thermophiles: Characterization Of An Arginine-Binding Protein In Thermotoga Maritima, Matthew S. Luchansky, Bryan S. Der, Sabato D'Auria, Gabriella Pocsfalvi, Luisa Iozzion, Daniela Marasco, Jonathan D. Dattelbaum
Amino Acid Transport In Thermophiles: Characterization Of An Arginine-Binding Protein In Thermotoga Maritima, Matthew S. Luchansky, Bryan S. Der, Sabato D'Auria, Gabriella Pocsfalvi, Luisa Iozzion, Daniela Marasco, Jonathan D. Dattelbaum
Chemistry Faculty Publications
Members of the periplasmic binding protein superfamily are involved in the selective passage of ligands through bacterial cell membranes. The hyperthermophilic eubacterium Thermotoga maritima was found to encode a highly stable and specific periplasmic arginine-binding protein (TM0593). Following signal sequence removal and overexpression in Escherichia coli, TM0593 was purified by thermoprecipitation and affinity chromatography. The ultra-stable protein with a monomeric molecular weight of 27.7 kDa was found to exist as both a homodimer and homotrimer at appreciable concentrations even under strongly denaturing conditions, with an estimated transition temperature of 116 °C. Its multimeric structure may provide further evidence of …
Amino Acid Transport In Thermophiles: Characterization Of An Arginine-Binding Protein In Thermotoga Maritima. 2. Molecular Organization And Structural Stability, Andrea Scirè, Anna Marabotti, Maria Staiano, Luisa Iozzion, Matthew S. Luchansky, Bryan S. Der, Jonathan D. Dattelbaum, Fabio Tanfani, Sabato D'Auria
Amino Acid Transport In Thermophiles: Characterization Of An Arginine-Binding Protein In Thermotoga Maritima. 2. Molecular Organization And Structural Stability, Andrea Scirè, Anna Marabotti, Maria Staiano, Luisa Iozzion, Matthew S. Luchansky, Bryan S. Der, Jonathan D. Dattelbaum, Fabio Tanfani, Sabato D'Auria
Chemistry Faculty Publications
ABC transport systems provide selective passage of metabolites across cell membranes and typically require the presence of a soluble binding protein with high specificity to a specific ligand. In addition to their primary role in nutrient gathering, the binding proteins associated with bacterial transport systems have been studied for their potential to serve as design scaffolds for the development of fluorescent protein biosensors. In this work, we used Fourier transform infrared spectroscopy and molecular dynamics simulations to investigate the physicochemical properties of a hyperthermophilic binding protein from Thermotoga maritima. We demonstrated preferential binding for the polar amino acid arginine …
Tuning Σ-Holes: Charge Redistribution In The Heavy (Group 14) Analogues Of Simple And Mixed Halomethanes Can Impose Strong Propensities For Halogen Bonding, Kelling J. Donald, Bernard K. Wittmaack, Chad Crigger
Tuning Σ-Holes: Charge Redistribution In The Heavy (Group 14) Analogues Of Simple And Mixed Halomethanes Can Impose Strong Propensities For Halogen Bonding, Kelling J. Donald, Bernard K. Wittmaack, Chad Crigger
Chemistry Faculty Publications
Halogen bonding between halide sites (in substituted organic molecules or inorganic halides) and Lewis bases is a rapidly progressing area of exploration. Investigations of this phenomenon have improved our understanding of weak intermolecular interactions and suggested new possibilities in supramolecular chemistry and crystal engineering. The capacity for halogen bonding is investigated at the MP2(full) level of theory for 100 compounds, including all 80 MH4-nXn systems (M = C, Si, Ge, Sn, and Pb; X = F, Cl, Br, and I). The charge redistribution in these molecules and the (in)stability of the σ-hole at X as …
Shorter Still: Compressing C-C Single Bonds, Gerarso Martinez-Guajardo, Kelling J. Donald, Bernard K. Wittmaack, Miguel Angel Vazquez, Gabriel Merino
Shorter Still: Compressing C-C Single Bonds, Gerarso Martinez-Guajardo, Kelling J. Donald, Bernard K. Wittmaack, Miguel Angel Vazquez, Gabriel Merino
Chemistry Faculty Publications
How short can a C-C single bond get? The bonding in a set of molecules that are related structurally to previously synthesized or theoretically examined systems with short C-C bonds is investigated. According to calculations, a single C-C bond could be compressed to 1.313 A! To the best of our knowledge, this is the shortest single C-C bond reported to date. This shortening is a consequence of a change in the C-C-C bond angle, θ, to minimize strain in the cages and an effort to offset the tension in the surrounding bridges.
Highly Nitrated Cyclopropanes As New High Energy Materials: Dft Calculations On The Properties Of C3H6−N(No2)N (N=3–6), Aloysus K. Lawong, David W. Ball
Highly Nitrated Cyclopropanes As New High Energy Materials: Dft Calculations On The Properties Of C3H6−N(No2)N (N=3–6), Aloysus K. Lawong, David W. Ball
Chemistry Faculty Publications
As part of a continuing study of new potential high energy materials, here we present results of calculations on cyclopropane molecules with three or more nitro groups. DFT calculations suggest that all molecules can exist as minimum-energy stationary states. Energy calculations indicate that some nitrocyclopropanes have a specific enthalpy of decomposition in excess of 8kJg−1, suggesting that they be explored as new potential high energy materials.
Double Superhelix Model Of High Density Lipoprotein, Zhiping Wu, Valentin Gogonea, Xavier Lee, Mathew A. Wagner
Double Superhelix Model Of High Density Lipoprotein, Zhiping Wu, Valentin Gogonea, Xavier Lee, Mathew A. Wagner
Chemistry Faculty Publications
High density lipoprotein (HDL), the carrier of so-called “good” cholesterol, serves as the major athero-protective lipoprotein and has emerged as a key therapeutic target for cardiovascular disease. We applied small angle neutron scattering (SANS) with contrast variation and selective isotopic deuteration to the study of nascent HDL to obtain the low resolution structure in solution of the overall time-averaged conformation of apolipoprotein AI (apoA-I) versus the lipid (acyl chain) core of the particle. Remarkably, apoA-I is observed to possess an open helical shape that wraps around a central ellipsoidal lipid phase. Using the low resolution SANS shapes of the protein …
Synthesis And Cytotoxic Analysis Of Some Disodium 3Β,6Β-Dihydroxysterol Disulfates, Jianguo Cui, Hui Wang, Yi Xin, Aimin Zhou
Synthesis And Cytotoxic Analysis Of Some Disodium 3Β,6Β-Dihydroxysterol Disulfates, Jianguo Cui, Hui Wang, Yi Xin, Aimin Zhou
Chemistry Faculty Publications
Disodium 3β,6β-dihydroxy-5α-cholestane disulfate (1) was synthesized in 4 steps with a high overall yield from cholesterol. First, cholesterol (4a) was converted to cholest-4-en-3,6-dione (5a) via oxidation with pyridinium chlorochromate (PCC) and then 5a was reduced by NaBH4 in the presence of NiCl2 to produce cholest-3β,6β-diol (6a). The reaction of 6a with the triethylamine-sulfur trioxide complex generated diammonium 3β,6β-dihydroxy-5α-cholestane disulfate (7a) and the treatment of 7a by cation exchange resin 732 (sodium form)(Na+) yielded the target steroid 1. Disodium 24-ethyl-3β,6β-dihydroxycholest-22-ene disulfate (2) and disodium 24-ethyl-3β,6β-dihydroxycholestane disulfate (3) were synthesized using a similar method. The cytotoxicity of these compounds against Sk-Hep-1 (human …
Lead Optimization Of Cox-2 Inhibitor Nimesulide Analogs To Overcome Aromatase Inhibitor Resistance In Breast Cancer Cells, Bin Su, Shiuan Chen
Lead Optimization Of Cox-2 Inhibitor Nimesulide Analogs To Overcome Aromatase Inhibitor Resistance In Breast Cancer Cells, Bin Su, Shiuan Chen
Chemistry Faculty Publications
A series of COX-2 selective inhibitor nimesulide derivatives were synthesized. Their anti-cell proliferation activities were evaluated with a long-term estrogen deprived MCF-7aro (LTEDaro) breast cancer cell line, which is the biological model of aromatase inhibitor resistance for hormone-dependent breast cancer. Compared to nimesulide which inhibited LTEDaro cell proliferation with an IC50 at 170.30 μM, several new compounds showed IC50 close to 1.0 μM.
Thermochromic Absorption And Photoluminescence In [Pt(Ppy)(Μ-Ph2pz)]2, Aaron A. Rachford, Felix N. Castellano
Thermochromic Absorption And Photoluminescence In [Pt(Ppy)(Μ-Ph2pz)]2, Aaron A. Rachford, Felix N. Castellano
Chemistry Faculty Publications
The temperature effects on the spectral properties and photophysics of a new d(8)-d(8) dinuclear Pt-II chromophore, [Pt(ppy)(mu-Ph(2)pz)](2) (ppy is 2-phenylpyridine and Ph(2)pz is 3,5-diphenylpyrazolate), have been investigated. The thermochromic shifts are tentatively ascribed to intramolecular sigma interactions between the two pseudocofacial d(Z2) orbitals. Substantial emission profile changes occur in the solid state, solution, and doped polymer films.
Modeling The Fluorescence Of Protein-Embedded Tryptophans With Ab Initio Multiconfigurational Quantum Chemistry: The Limiting Cases Of Parvalbumin And Monellin, Sara Pistolesi, Adalgisa Sinicropi, Rebecca Pogni, Riccardo Basosi, Nicolas Ferre, Massimo Olivucci
Modeling The Fluorescence Of Protein-Embedded Tryptophans With Ab Initio Multiconfigurational Quantum Chemistry: The Limiting Cases Of Parvalbumin And Monellin, Sara Pistolesi, Adalgisa Sinicropi, Rebecca Pogni, Riccardo Basosi, Nicolas Ferre, Massimo Olivucci
Chemistry Faculty Publications
We show that a quantum-mechanics/molecular-mechanics strategy based on ab initio (i.e., first principle) multiconfigurational perturbation theory can reproduce the spectral properties of a tryptophan residue embedded in the contrasting hydrophobic and hydrophilic environments of parvalbumin and monellin, respectively. We show that the observed absorption and emission energies can be reproduced with a less than 3 kcal mol(-1) error. The analysis of the computed emission energies based on a protein disassembly scheme and protein electrostatic potential mapping allows for a detailed understanding of the factors modulating the tryptophan emission. It is shown that for rnonellin, where the tryptophan is exposed to …
Determination Of 6-Benzylthioinosine In Mouse And Human Plasma By Liquid Chromatography–Tandem Mass Spectrometry, Lan Li, Yan Xu, David N. Wald, William Tse
Determination Of 6-Benzylthioinosine In Mouse And Human Plasma By Liquid Chromatography–Tandem Mass Spectrometry, Lan Li, Yan Xu, David N. Wald, William Tse
Chemistry Faculty Publications
This paper described the development and validation of a liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the quantitative determination of 6-benzylthioinosine (6BT), a novel myeloid leukemia differentiation-inducing agent, in mouse and human plasma. In this method, 2-amino-6-benzylthioinosine (2A6BT) was used as internal standard and ethyl acetate was used as organic solvent for the extraction of 6BT and internal standard from plasma samples. The extracted samples were separated on YMC ODS-AQ® column (2.0 mm × 50 mm), and the eluates from the column were monitored by the positive-electrospray-ionization tandem mass spectrometer (ESI+-MS/MS). Quantification of 6BT by internal calibration with 2A6BT was …
Synthesis And Evaluation Of Some Steroidal Oximes As Cytotoxic Agents: Structure/Activity Studies (Ii), Jianguo Cui, Lei Fan, Yanmin Huang, Yi Xin, Aimin Zhou
Synthesis And Evaluation Of Some Steroidal Oximes As Cytotoxic Agents: Structure/Activity Studies (Ii), Jianguo Cui, Lei Fan, Yanmin Huang, Yi Xin, Aimin Zhou
Chemistry Faculty Publications
Hydroximinosteroids isolated from marine sponges display a variety of biological functions including cytotoxicity and anti-virus. In this study, we synthesized a series of hydroximinosteroid derivatives with a different functional group on the ring A or B and various side chains at position 17, and analyzed the cytotoxicity of these compounds against sk-Hep-1, H-292, PC-3 and Hey-1B cancer cells. Our results revealed that although a cholesterol-type side chain at position 17 is required for the biological activity of the compounds as we previously confirmed, elimination of the 4,5-double bond augmented the cytotoxic activity for the steroidal oximes. In addition, the presence …
How Does The Relocation Of Internal Water Affect Resonance Raman Spectra Of Rhodopsin? An Insight From Casscf/Amber Calculations, Tadeusz Andruniow, Massimo Olivucci
How Does The Relocation Of Internal Water Affect Resonance Raman Spectra Of Rhodopsin? An Insight From Casscf/Amber Calculations, Tadeusz Andruniow, Massimo Olivucci
Chemistry Faculty Publications
The effect of relocation of the W2 crystallographic water in bovine rhodopsin has been investigated by comparing and analyzing simulated resonance Raman spectra of I HZX-and 1U19-based quantum mechanics/molecular mechanics (CASSCF/MM) models. The main target is to explore the sensitivity of the simulated resonance Raman spectra to protein cavity change. In particular, we focus on a quantitative investigation of the changes in the vibrational activity of rhodopsin induced by modifications in the protein cavity structure and in the water position. Comparison of the simulated FIR spectra of the Rh-1U19 and Rh-1HZX models with the measured spectrum of rhodopsin reveals that …
Improving Replica Exchange Using Driven Scaling, Steven W. Rick
Improving Replica Exchange Using Driven Scaling, Steven W. Rick
Chemistry Faculty Publications
Replica exchange is a powerful simulation method in which simulations are run at a series of temperatures, with the highest temperature chosen so phase space can be sampled efficiently. In order for swaps to be accepted, the energy distributions of adjacent replicas must have some overlap. This can create the need for many replicas for large systems. In this paper, we present a new method in which the potential energy is scaled by a parameter, which has an explicit time dependence. Scaling the potential energy broadens the distribution of energy and reduces the number of replicas necessary to span a …
Structure Of The Photochemical Reaction Path Populated Via Promotion Of Cf2i2 Into Its First Excited State, Patrick Z. El-Khoury, Alexander N. Tarnovsky, Igor Schapiro, Mikhail N. Ryazantsev, Massimo Olivucci
Structure Of The Photochemical Reaction Path Populated Via Promotion Of Cf2i2 Into Its First Excited State, Patrick Z. El-Khoury, Alexander N. Tarnovsky, Igor Schapiro, Mikhail N. Ryazantsev, Massimo Olivucci
Chemistry Faculty Publications
The photochemical reaction path following the promotion of CF2I2 into its lowest-lying excited electronic singlet state has been modeled using ab initio multiconfigurational quantum chemical calculations. It is found that a conical intersection drives the electronically excited CF2I2* species either to the CF2I + I radical pair or back to the starting CF2I2 structure. The structures of the computed relaxation pathways explain the photoproduct selectivity previously observed in the gas phase. Furthermore, the results provide the basis for explaining the condensed-phase photochemistry of CF2I2.
Distance Dependence Of Electron Transfer Kinetics For Azurin Protein Adsorbed To Monolayer Protected Nanoparticle Film Assemblies, Morgan Lynn Vargo, Chris P. Gulka, John K. Gerig, Christopher M. Manieri, Jonathan D. Dattelbaum, Carolyn B. Marks, Nathaniel T. Lawrence, Matthew L. Trawick, Michael C. Leopold
Distance Dependence Of Electron Transfer Kinetics For Azurin Protein Adsorbed To Monolayer Protected Nanoparticle Film Assemblies, Morgan Lynn Vargo, Chris P. Gulka, John K. Gerig, Christopher M. Manieri, Jonathan D. Dattelbaum, Carolyn B. Marks, Nathaniel T. Lawrence, Matthew L. Trawick, Michael C. Leopold
Chemistry Faculty Publications
The distance dependence and kinetics of the heterogeneous electron transfer (ET) reaction for the redox protein azurin adsorbed to an electrode modified with a gold nanoparticle film are investigated using cyclic voltammetry. The nanoparticle films are comprised of nonaqueous nanoparticles, known as monolayer-protected clusters (MPCs), which are covalently networked with dithiol linkers. The MPC film assembly serves as an alternative adsorption platform to the traditional alkanethiolate self-assembled monolayer (SAM) modified electrodes that are commonly employed to study the ET kinetics of immobilized redox proteins, a strategy known as protein monolayer electrochemistry. Voltammetric analysis of the ET kinetics for azurin adsorbed …
Pinpointing The Extent Of Electronic Delocalization In The Re(I)-To-Tetrazine Charge-Separated Excited State Using Time-Resolved Infrared Spectroscopy, Guifeng Li, Kumar Parimal, Shubham Vyas, Christopher M. Hadad, Amar H. Flood, Ksenija D. Glusac
Pinpointing The Extent Of Electronic Delocalization In The Re(I)-To-Tetrazine Charge-Separated Excited State Using Time-Resolved Infrared Spectroscopy, Guifeng Li, Kumar Parimal, Shubham Vyas, Christopher M. Hadad, Amar H. Flood, Ksenija D. Glusac
Chemistry Faculty Publications
Femtosecond mid-IR transient absorption spectroscopy (TRIR) and time-dependent density functional theory (TD-DFT) calculations on Re(CO)(3)Cl(Me(2)BPTZ) [Me(2)BPTZ = 3,6-bis(5-methyl-2-pyridine)-1,2,4,5-tetrazine] are used to demonstrate that the lowest excited state of the complex is a triplet metal-to-ligand charge-transfer ((3)MLCT) state with a lifetime of 225 ps. The short excited-state lifetime is explained by the energy-gap taw. Vibrational cooling of the (3)MLCT state shows up as early-time dynamics (3.6 ps). The structural changes in the excited state are deduced from the frequency shifts in the TRIR vibrational bands. The vibrational frequencies of the CO groups increase upon excitation as a result of decreased back-bonding …