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https://www.readbyqxmd.com/read/28735233/a-model-system-to-mimic-environmentally-active-surface-film-roughness-and-hydrophobicity
#1
Jacob S Grant, Scott K Shaw
This work presents the development and initial assessment of a laboratory platform to allow quantitative studies on model urban films. The platform consists of stearic acid and eicosane mixtures that are solution deposited from hexanes onto smooth, solid substrates. We show that this model has distinctive capabilities to better mimic a naturally occurring film's morphology and hydrophobicity, two important parameters that have not previously been incorporated into model film systems. The physical and chemical properties of the model films are assessed using a variety of analytical instruments...
July 14, 2017: Chemosphere
https://www.readbyqxmd.com/read/28735221/physicochemical-properties-of-ionic-and-non-ionic-biocompatible-hydrogels-in-water-and-cell-culture-conditions-relation-with-type-of-morphologies-of-bovine-fetal-fibroblasts-in-contact-with-the-surfaces
#2
Rebeca Rivero, Fabrisio Alustiza, Virginia Capella, Cecilia Liaudat, Nancy Rodriguez, Pablo Bosch, Cesar Barbero, Claudia Rivarola
Cationic, anionic and non-ionic hydrogels having acrylamide polymer backbones were synthesized via free radical polymerization with N,N-methylenebisacrylamide (BIS) as crosslinker. The chemical structures of the hydrogels were characterized by Fourier Transform Infrared Spectroscopy (FTIR). Physicochemical properties such as swelling kinetic, maximum swelling capacity, volume phase transition temperature (VPTT) and wettability (static water contact angle) of hydrogels swollen in aqueous and cell culture medium, at room and cell culture temperatures were studied...
July 11, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28735171/encoding-of-coordination-complexes-with-xml
#3
P Vinoth, P Sankar
An in-silico system to encode structure, bonding and properties of coordination complexes is developed. The encoding is achieved through a semantic XML markup frame. Composition of the coordination complexes is captured in terms of central atom and ligands. Structural information of central atom is detailed in terms of electron status of valence electron orbitals. The ligands are encoded with specific reference to the electron environment of ligand centre atoms. Behaviour of ligands to form low or high spin complexes is accomplished by assigning a Ligand Centre Value to every ligand based on the electronic environment of ligand centre atom...
July 13, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28734839/recombinant-expression-of-ixolaris-a-kunitz-type-inhibitor-from-the-tick-salivary-gland-for-nmr-studies
#4
V S De Paula, F H S Silva, I M B Francischetti, R Q Monteiro, A P Valente
Ixolaris is an anticoagulant protein identified in the tick saliva of Ixodes scapularis. Ixolaris contains 2 Kunitz like domains and binds to Factor Xa or Factor X as a scaffold for inhibition of the Tissue Factor (TF)/Factor VIIa (FVIIa). In contrast to tissue factor pathway inhibitor (TFPI), however, Ixolaris does not bind to the active site cleft of FXa. Instead, complex formation is mediated by the FXa heparin-binding exosite. Due to its potent and long-lasting antithrombotic activity, Ixolaris is a promising agent for anticoagulant therapy...
July 19, 2017: Protein Expression and Purification
https://www.readbyqxmd.com/read/28734568/antibacterial-properties-of-nano-silver-coated-peek-prepared-through-magnetron-sputtering
#5
Xiuju Liu, Kang Gan, Hong Liu, Xiaoqing Song, Tianjie Chen, Chenchen Liu
OBJECTVE: We aimed to investigate the cytotoxicity and antibacterial properties of nano-silver-coated polyetheretherketone (PEEK) produced through magnetron sputtering and provide a theoretical basis for its use in clinical applications. METHODS: The surfaces of PEEKs were coated with nano-silver at varying thicknesses (3, 6, 9, and 12nm) through magnetron sputtering technology. The resulting coated PEEK samples were classified into the following groups according to the thickness of the nano-silver coating: PEEK-3 (3nm), PEEK-6 (6nm), PEEK-9 (9nm), PEEK-12 (12nm), and PEEK control group...
July 19, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/28734363/multi-energy-calibration-applied-to-atomic-spectrometry
#6
Alex Virgilio, Daniel A Gonçalves, Tina McSweeney, José A Gomes Neto, Joaquim A Nóbrega, George L Donati
Multi-energy calibration (MEC) is a novel strategy that explores the capacity of several analytes of generating analytical signals at many different wavelengths (transition energies). Contrasting with traditional methods, which employ a fixed transition energy and different analyte concentrations to build a calibration plot, MEC uses a fixed analyte concentration and multiple transition energies for calibration. Only two calibration solutions are required in combination with the MEC method. Solution 1 is composed of 50% v v(-1) sample and 50% v v(-1) of a standard solution containing the analytes...
August 22, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28734313/singlet-fission-in-chiral-carbon-nanotubes-density-functional-theory-based-computation
#7
Andrei Kryjevski, Deyan Mihaylov, Brendan Gifford, Dmitri Kilin
Singlet fission (SF) process, where a singlet exciton decays into a pair of spin one exciton states which are in the total spin singlet state, is one of the possible channels for multiple exciton generation (MEG). In chiral single-wall carbon nanotubes (SWCNTs), efficient SF is present within the solar spectrum energy range which is shown by the many-body perturbation theory calculations based on the density functional theory simulations. We calculate SF exciton-to-biexciton decay rates R1→2 and biexciton-to-exciton rates R2→1 in the (6,2), (6,5), (10,5) SWCNTs, and in the (6,2) SWCNT functionalized with Cl atoms...
July 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28734309/universal-two-dimensional-characteristics-in-perovskite-type-oxyhydrides-atio2h-a-li-na-k-rb-cs
#8
Nobuya Sato, Ryosuke Akashi, Shinji Tsuneyuki
A series of unsynthesized perovskite-type oxyhydrides ATiO2H (A = Li, Na, K, Rb, Cs) are investigated by the density functional calculations. These oxyhydrides are stable in the sense of the formation energies for some possible synthesis reactions. They are crystallized into quite similar crystal structures with the long c-axis, and the corner-sharing TiO4H2 octahedra of the ideal perovskite-type structure are deformed into the 5-fold coordinated titanium atoms with the OH plane and the apical oxygen atoms...
July 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28734307/a-confinement-induced-spectroscopic-study-of-noble-gas-atoms-using-equation-of-motion-architecture-encapsulation-within-fullerene-s-voids
#9
Supriya K Chaudhuri, Rajat K Chaudhuri, Prasanta K Mukherjee, Sudip Chattopadhyay
A relativistic study of spectroscopic properties of the endohedral fullerenes Ng@C60(q) (where Ng = He, Ne and q=0,±1,±2 are the charges) associated with the C60 molecule has been done using the equation of motion coupled cluster (EOM-CC) methodology. Specific properties estimated are the transition energies, dipole oscillator strengths, and transition probabilities for the low-lying excitations 1s(2)((1)S0) → 1snp ((1)P1) (n = 2, 3, 4) for He@C60(q) and 1s(2)2s(2)2p(6) ((1)S0) → 1s(2)2s(2)2p(5)ns∕nd ((1)P1) (n = 3, 4) for Ne@C60(q), which have been compared with those for the isolated atom to depict the confinement effect of the host molecule on the encapsulated atom...
July 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28734299/state-of-the-art-ab-initio-potential-energy-curve-for-the-xenon-atom-pair-and-related-spectroscopic-and-thermophysical-properties
#10
Robert Hellmann, Benjamin Jäger, Eckard Bich
A new ab initio interatomic potential energy curve for two ground-state xenon atoms is presented. It is based on supermolecular calculations at the coupled-cluster level with single, double, and perturbative triple excitations [CCSD(T)] employing basis sets up to sextuple-zeta quality, which were developed as part of this work. In addition, corrections were determined for higher coupled-cluster levels up to CCSDTQ as well as for scalar and spin-orbit relativistic effects at the CCSD(T) level. A physically motivated analytical function was fitted to the calculated interaction energies and used to compute the vibrational spectrum of the dimer, the second virial coefficient, and the dilute gas transport properties...
July 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28734295/estimating-the-intrinsic-limit-of-the-feller-peterson-dixon-composite-approach-when-applied-to-adiabatic-ionization-potentials-in-atoms-and-small-molecules
#11
David Feller
Benchmark adiabatic ionization potentials were obtained with the Feller-Peterson-Dixon (FPD) theoretical method for a collection of 48 atoms and small molecules. In previous studies, the FPD method demonstrated an ability to predict atomization energies (heats of formation) and electron affinities well within a 95% confidence level of ±1 kcal/mol. Large 1-particle expansions involving correlation consistent basis sets (up to aug-cc-pV8Z in many cases and aug-cc-pV9Z for some atoms) were chosen for the valence CCSD(T) starting point calculations...
July 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28734289/perspective-photocatalytic-reduction-of-co2-to-solar-fuels-over-semiconductors
#12
Chao Peng, Glenn Reid, Haifeng Wang, P Hu
Increasing emissions of carbon dioxide and the depletion of finite fossil fuels have led to many concerns about global warming and energy crises. Consequently, a sustainable and alternative method, photocatalytic CO2 reduction to chemical fuels has received considerable attention. This perspective highlights recent knowledge and the main challenges in CO2 photoreduction primarily from the theoretical field. The fundamental understanding of CO2 adsorption and reaction mechanism at an atomic level is fully addressed, and the relevant effects dominating the process of CO2 photoreduction are also elucidated...
July 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28734285/extension-of-the-d3-dispersion-coefficient-model
#13
Eike Caldeweyher, Christoph Bannwarth, Stefan Grimme
A new model, termed D4, for the efficient computation of molecular dipole-dipole dispersion coefficients is presented. As in the related, well established D3 scheme, these are obtained as a sum of atom-in-molecule dispersion coefficients over atom pairs. Both models make use of dynamic polarizabilities obtained from first-principles time-dependent density functional theory calculations for atoms in different chemical environments employing fractional atomic coordination numbers for interpolation. Different from the D3 model, the coefficients are obtained on-the-fly by numerical Casimir-Polder integration of the dynamic, atomic polarizabilities α(iω)...
July 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28734276/embedding-for-bulk-systems-using-localized-atomic-orbitals
#14
F Libisch, M Marsman, J Burgdörfer, G Kresse
We extend projection-based embedding techniques to bulk systems to treat point defects in semiconductors and insulators. To avoid non-additive kinetic energy contributions, we construct the density partition using orthogonal subsets of orbitals. We have implemented our approach in the popular Vienna ab initio simulation package software package. We demonstrate its power for defect structures in silicon and polaron formation in titania, two challenging cases for conventional Kohn-Sham density functional theory...
July 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28734245/azaphenothiazines-promising-phenothiazine-derivatives-an-insight-into-nomenclature-synthesis-structure-elucidation-and-biological-properties
#15
REVIEW
Krystian Pluta, Małgorzata Jeleń, Beata Morak-Młodawska, Michał Zimecki, Jolanta Artym, Maja Kocięba, Ewa Zaczyńska
For the last two decades, classical phenothiazines have attracted attention of researchers, as the hitherto investigations have revealed many significant biological activities within this class of compounds, other than originally discovered neuroleptic ones. Important, new pharmaceutical results on phenothiazines, as 10-substituted dibenzothiazines, were recently highlighted in several reviews. Azaphenothiazines are structurally modified phenothiazines by substitution of one or both benzene rings in the phenothiazine ring system with the azine rings, such as: pyridine, pyridazine, pyrimidine, pyrazine, 1,2,4-triazine, quinoline, quinoxaline, benzoxazine and benzothiazine...
July 8, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28734220/effect-analysis-of-quantum-chemical-descriptors-and-substituent-characteristics-on-henry-s-law-constants-of-polybrominated-diphenyl-ethers-at-different-temperatures
#16
Jiang Long, Qiu Youli, Li Yu
Twelve substituent descriptors, 17 quantum chemical descriptors and 1/T were selected to establish a quantitative structure-property relationship (QSPR) model of Henry's law constants for 7 polybrominated diphenyl ethers (PBDEs) at five different temperatures. Then, the lgH of 202 congeners at different temperatures were predicted. The variation rule and regulating mechanism of lgH was studied from the perspectives of both quantum chemical descriptors and substituent characteristics. The R(2) for modeling and testing sets of the final QSPR model are 0...
July 19, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28734204/molecular-dynamics-of-conformation-specific-dopamine-transporter-inhibitor-complexes
#17
Bernandie Jean, Christopher K Surratt, Jeffry D Madura
The recreational psychostimulant cocaine inhibits dopamine reuptake from the synapse, resulting in excessive stimulation of postsynaptic dopamine receptors in brain areas associated with reward and addiction. Cocaine binds to and stabilizes the outward- (extracellular-) facing conformation of the dopamine transporter (DAT) protein, while the low abuse potential DAT inhibitor benztropine prefers the inward- (cytoplasmic-) facing conformation. A correlation has been previously postulated between psychostimulant abuse potential and preference for the outward-facing DAT conformation...
July 11, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28734100/oxygenation-of-simple-olefins-via-selective-allylic-c-c-bond-cleavage-a-direct-approach-to-cinnamyl-aldehydes
#18
Ning Jiao, Jianzhong Liu, Xiaojin Wen, Chong Qin, Xiao Luo, Ao Sun, Bencong Zhu, Song Song, Xinyao Li
A novel metal-free allylic C-C σ-bond cleavage of simple olefins leading to valuable cinnamyl aldehydes is reported. 1,2-Aryl or alkyl migration through allylic C-C bond cleavage occurs in this transformation assisted by an alkyl azide reagent. This protocol enables the O-atom incorporation into simple unfunctionalized olefins to construct cinnamyl aldehydes. The chemistry features simple hydrocarbon substrates, metal-free conditions, and high regio- and stereo-selectivities.
July 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28733969/tailoring-ion-charge-state-distribution-in-tetramethyltin-clusters-under-influence-of-moderate-intensity-picosecond-laser-pulse-role-of-laser-wavelength-and-rate-of-energy-deposition
#19
Pramod Sharma, Soumitra Das, Rajesh K Vatsa
Systematic manipulation of ionic-outcome in laser-cluster interaction process has been realized for studies carried out on tetramethyltin (TMT) clusters under picosecond laser conditions, determined by choice of laser wavelength and intensity. As a function of laser intensity, TMT clusters exhibit gradual enhancement in overall ionization of its cluster constituents, up to a saturation level of ionization, which was distinct for different wavelengths (266, 355, and 532 nm). Simultaneously, systematic appearance of higher multiply charged atomic ions and shift in relative abundance of multiply charged atomic ions towards higher charge state was observed, using time-of-flight mass spectrometer...
July 21, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28733937/sequential-extraction-as-novel-approach-to-compare-12-medicinal-plants-from-kenya-regarding-their-potential-to-release-chromium-manganese-copper-and-zinc
#20
R Mogwasi, S Zor, D K Kariuki, M Z Getenga, V Nischwitz
This study is focusing on a novel approach to screen a large number of medicinal plants from Kenya regarding their contents and availability of selected metals potentially relevant for treatment of diabetes patients. For this purpose, total levels of zinc, chromium, manganese, and copper were determined by flame atomic absorption spectrometry and inductively coupled plasma mass spectrometry as well as BCR sequential extraction to fractionate the elemental species in anti-diabetic medicinal plants collected from five natural locations in two sub counties in Nyamira County, Kenya...
July 21, 2017: Biological Trace Element Research
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