bluuebunny/crossref_metadata_2025_split huggingface dataset:
Permittivity measurements in nanostructured TiO2 gas sensors
Authors: Giberti A. , Carotta M. C. , Malagù C. , Aldao C. M. , Castro M. S. , Ponce M. A. , Parra R. 
Published: October 2010

AbstractResistance and capacitance measurements, as a function of frequency, were carried out to analyze and model the electrical behavior of undoped titanium dioxide (TiO2) films. The sensing measurements were carried out in a chamber with independent temperature, pressure, gas composition, and flow rate control. With the aim of evaluating the electrical response of the sample as a function of the surrounding atmosphere, a frequency range of 100 Hz–4 MHz was used (vacuum or air at atmospheric pressure). The resistance and capacitance responses were obtained with the help of impedance spectroscopy technique. The impedance response versus frequency allows the discrimination between grain‐boundary capacitance (Cgb) and resistance (Rgb) contributions. A model, taking into account the possible effects due to grain size is proposed in order to work out the permittivity of the material.
Evidence that the marine‐derived multi‐mineral aquamin has anti‐inflammatory effects on cortical glial‐enriched cultures
Authors: Ryan Sinead , O'Gorman Denise M. , Nolan Yvonne M. 
Published: October 2010

AbstractIt is well established that neuroinflammation contributes to brain aging, and that cortical cells are particularly vulnerable. Lipopolysaccharide stimulates the release of the pro‐inflammatory cytokines, tumor necrosis factor‐alpha and interleukin‐1beta from glial cells which consequently induces an impairment in neuronal cell function. The food supplement, Aquamin, is a natural, multi‐mineral derived from the red algae Lithothamnion corallioides, rich in calcium, magnesium and 72 other trace minerals. The aim of this study was to evaluate the anti‐inflammatory potential of Aquamin in lipopolysaccharide‐stimulated, glial‐enriched primary cultures of rat cortex. It is reported that Aquamin prevented lipopolysaccharide‐induced secretion of tumor necrosis factor‐alpha and interleukin‐1beta from cortical glia. These data suggest that nutritional supplements such as Aquamin may play an important role in impeding the detrimental effects of excessive inflammation in the brain. Copyright © 2010 John Wiley & Sons, Ltd.
The functionality of cation bridges for binding polar groups in soil aggregates
Authors: Aquino Adélia J. A. , Tunega Daniel , Schaumann Gabriele E. , Haberhauer Georg , Gerzabek Martin H. , Lischka Hans 
Published: October 2010

AbstractStructural and energetic properties of cation bridges in soil supramolecular aggregates were studied by means of a model system in which two carboxylate groups connected to aliphatic oligomer chains were bound by Ca2+ and Na+, respectively. Wetting/drying conditions in soils because of environmental changes were modeled by different content of water molecules forming the solvation shell of the cations. Density functional theory calculations were performed for unpolar (isolated structures) and polar (water as continuum polarization model) environment. Direct and indirect complexes of the cations with the carboxylate groups were found to have different stability. Formation of indirect complexes was computed by means of potential energy curves for the approach of bare (reference set) and solvated cations to the dimer chain containing the carboxylate groups. Characteristic difference on drying (stepwise reduction of water molecules) between Ca2+ and Na+ complexes were observed affecting the predicted mobility of monovalent and divalent cations in soils. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Experimental and theoretical studies on the inhibition potentials of some derivatives of cyclopenta‐1,3‐diene for the corrosion of mild steel in HCl solutions
Authors: Eddy Nnabuk O. , Ita Benedict I. 
Published: October 2010

AbstractThe inhibition of the corrosion of mild steel in HCl by some cyclopentadiene‐1,3‐diene derivatives, namely, 1‐(thiophen‐2‐yl)ethanone (2APT), 1‐(1H‐pyrrol‐2‐yl)ethanone (2AP), and (E)‐2‐(1‐hydrazonoethyl)‐1H‐pyrrole (2APH)), was studied experimentally using weight loss and hydrogen gas evolution measurements. The theoretical aspect was studied using the density functional theory and quantitative structure activity relation (QSAR) methods. The results obtained indicated that the studied compounds are good inhibitors for the corrosion of mild steel in HCl. The adsorption of the inhibitor on mild steel surface was found to be spontaneous, exothermic, and obeyed the Langmuir adsorption isotherm model. A good correlation was found between experimental inhibition efficiencies and some calculated quantum chemical parameters and also with the theoretical inhibition efficiencies obtained from QSAR modeling. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Theoretical studies on the structural rearrangement of ligand binding pocket in human vitamin D receptor
Authors: Wang Jinhu , Tang Ke , Hou Qianqian , Cheng Xueli , Liu Yongjun , Liu Chengbu 
Published: October 2010

AbstractThe structural rearrangement of the ligand binding domain (LBD) of human Vitamin D receptor (hVDR) complexed with 1α, 25‐dihydroxyvitamin D3 (natural ligand) and its analogues (denoted as b and c) was studied by molecular dynamics (MD) simulations. MD simulations revealed that these ligands could induce different structural changes of LBD, in which 1α, 25‐dihydroxyvitamin D3 only led to a minute change, suggesting that LBD adopted its canonical active conformation upon binding the natural ligand, while b and c could provoke a clear structural rearrangement of the LBD. In complex of hVDR‐LBD/b, it is found that helix 6 (H6) and subsequent loop 6‐7 shift outward and the last turn of H11 shifts away from H12, which generate a new cavity at the bottom of binding pocket to accommodate the extra butyl group on the side chain of ligand b. As for hVDR‐LBD/c, the steric exclusion of the second side chain of ligand c makes the N‐terminal of H7 move outsides and C‐terminal of H11 close to H12, expanding the bottom of the pocket. These calculation results agree well the experimental observations. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Theoretical and experimental studies on electronic structure, cocrystallization, and intramolecular proton transfer of two tautomers: (E)‐2‐{[2‐(hydroxymethyl)phenylimino]methyl}‐5‐methoxyphenol and (Z)‐6‐{[2‐(hydroxymethyl)phenylamino] methylene}‐3‐methoxy‐cyclohexa‐2, 4‐dienone
Authors: Koşar Başak , Albayrak Çiǧdem , Odabaşoǧlu Mustafa , Büyükgüngör Orhan 
Published: October 2010

AbstractIn this work, the structure of (E)‐2‐{[2‐(hydroxymethyl) phenylimino]methyl}‐5‐methoxyphenol was characterized by X‐ray single crystal diffraction technique, infrared spectroscopy, and quantum chemical computational methods as both experimental and theoretically. The compound crystallizes in the triclinic space group P1 with a = 9.4601 (5) Å, b = 11.7273 (7) Å, c = 12.4400 (8) Å, α = 88.179 (5)°, β = 71.442 (4)°, γ = 84.977 (5)°, and Z = 4. X‐Ray study shows that both enol–imine and keto–amine tautomeric forms coexist in the asymmetric unit as two independent molecules. The molecular geometry was also optimized at the B3LYP/6‐311G(d,p) level by using density functional theory started from the crystallographically achieved parameters of molecule. From the optimized geometry of the molecule, molecular electrostatic potential was evaluated, frontier molecular orbitals and natural bond orbital analysis were performed, and vibrational frequencies were computed theoretically. The polarizable continuum model calculations starting from the optimized geometry were also carried out in both gaseous and solution phase to investigate the energetic behavior and dipole moment of the title compound with the same level of theory. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Substituent effect on structure, electron density, and intramolecular hydrogen bonding in nitroso‐oxime methane
Authors: Yoosefian Mehdi , Raissi Heidar , Nadim Emad Saleh , Farzad Farzaneh , Fazli Mustapha , Karimzade Elham , Nowroozi Alireza 
Published: October 2010

AbstractDensity functional calculations with Beck's three‐parameter hybrid method using the correlation functional of Lee, Yang, and Parr (B3LYP) were carried out for investigation of the intramolecular hydrogen bond strength in Nitroso‐oxime methane and its derivatives. Also, vibrational frequencies for them were calculated at the same level of theory. The π‐electron delocalization parameter (Q) and as a geometrical indicator of a local aromaticity, the geometry‐based harmonic oscillator measure of aromaticity index has been applied. Additionally, the linear correlation coefficients between substituent constants and selected parameters in R position have calculated. The obtained results show that the hydrogen bond strength is mainly governed by the resonance variations inside the chelate ring induced by the substituent groups. The topological properties of the electron density distributions for OH···O intramolecular bridges have been analyzed in terms of the Bader theory of atoms in molecules (AIM). Correlations between the H‐bond strength and topological parameters have been also studied. The electron density (ρ) and Laplacian (∇2ρ) properties, estimated by AIM calculations, show that O···H bond have low ρ and negative (∇2ρ) values (consistent with covalent character of the HBs), whereas OH bond have positive (∇2ρ) Furthermore, the analysis of hydrogen bond in this molecule and its derivatives by quantum theory of natural bond orbital (NBO) methods fairly support the ab initio results. Natural population analysis data, the electron density, and Laplacian properties as well as υ(OH) and γ(OH) were further used for estimation of the hydrogen bonding interactions and the forces driving their formation. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
DFT and Ab initio computational study on the reactivity sites of the GABA and its agonists, such as CACA, TACA, DABA, and muscimol: In the gas phase and dielectric media
Authors: Serdaroğlu Goncagül 
Published: October 2010

AbstractThe reactive behavior of GABA and its agonist molecules have been investigated using B3LYP hybrid density functional method at the 6‐311++G** basis set level, in the gas phase and dielectric media. The calculations have been performed to obtain optimized geometries, relative energies, net atomic charges, HOMO, and LUMO energies. Solvent effects have been analyzed using isodensity polarized continuum model (IPCM) for four different solvents, which are chloroform, ethanol, DMSO, and H2O. The results have suggested that both the amino group and carboxyl group have been two of the most important active site for interactions between all compounds and their receptors. In addition they have suggested that the amino group reflects the difference in biological activity for each all molecules. The structures of these agonists have provided an essential foundation for subsequent structure‐activity analysis of ligand binding at GABA receptors, neuronal uptake inhibitors and transporters. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Analysis of the nitrile and methyl torsional vibrations of n‐propyl cyanide in its S0 electronic state
Authors: Castro M. E. , Muñoz‐Caro C. , Niño A. 
Published: October 2010

AbstractThis work presents a structural and vibrational theoretical study of n‐propyl cyanide as a function of the nitrile and methyl torsional modes. A potential energy hypersurface is built at the MP4(SDQ)/aug‐cc‐pVTZ//MP2/aug‐cc‐pVTZ theory level. The equilibrium structure is found in a gauche conformation. Another minimum is found for the trans form. The maximum appears in a cis conformation. For the first time, the interconversion barriers between the different forms are calculated. A two‐dimensional anharmonic vibrational Hamiltonian is built for the nitrile and methyl torsional modes. We find the vibrational energy levels to organize in two stacks associated to the gauche and trans forms. Fundamental frequencies of 113.12 and 220.54 cm−1 are predicted for the nitrile and methyl torsions in the equilibrium, gauche, conformer. In addition, we find symmetry allowed transitions between the gauche and trans energy levels stacks. The lowest transition is predicted to appear at 24.49 cm−1. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Theoretical investigation on the IR spectra of four‐membered silicon oxide ring
Authors: Mhin Byung Jin , Seo Hyun‐Il , Kim Seung‐Joon 
Published: October 2010

AbstractTo test the mass effect on the ring vibrational frequencies (SiO2) shift of the four‐membered silicon oxide ring, the deuterium and the tritium substituted cyclodisiloxanes on the hydrogen positions are examined at the CCSD(T)/cc‐pVTZ level of theory. The SiO2 ring vibrations for a silicon oxide surface model compound, substituted cyclodisiloxane (Si3O5O2Si3O5) with two six‐membered ring, are also calculated at the B3LYP/cc‐pVTZ level of theory. Our results of 909 and 920 cm−1 are in good agreement with the experimental result. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Steric and electronic effects on the heterolytic H2‐splitting by phosphine‐boranes R3B/PR′3(R = C6F5, Ph; R′ = C6H2Me3,tBu, Ph, C6F5, Me, H): A computational study
Authors: Gao Shulin , Wu Wei , Mo Yirong 
Published: October 2010

AbstractThe steric and electronic effects exerted by the substituents R/R′ on the heterolytic H2‐splitting by phosphine‐boranes R3B/PR′3[R = C6F5(1), Ph (2); R′ = C6H2Me3(a),tBu (b), Ph (c), C6F5(d), Me (e), H (f)] have been studied by performing quantum mechanical density functional theory and RI‐MP2 calculations. Energy decomposition analyses based on the block‐localized wavefunction method show that the nature of the interaction between R3B and PR′3is strongly dependent on the BP distance. With short BP distances (∼2.1 Å), the strength of Lewis pairs results from the balance among various energy terms, and both strong and weak dative bonds can be found in this group. However, at long BP distances (>4.0 Å), the correlation and dispersion energy (ΔEcorr) dominates. In other words, the van der Waals (vdW) interaction rules these weakly bound complexes. No ion‐pair structures of1fand2c–2fcan be located as they instantly converge to vdW complexes R3B···H2···PR′3. We thus propose a model, which predicts that when the sum (Ehp) of the hydride affinity (HA) of BR3and the proton affinity (PA) of PR′3is higher than 340.0 kcal/mol, the ion‐pair [R3BH−][HPR′] can be observed, whereas withEhpbelow this value, the ion pair would instantly undergo the combination of proton and hydride with the release of H2. The overall reaction energies (1a–1eand2a–2b) can be best described by a fitting equation with HA(BR3), PA(PR′3), and the binding energy ΔEb(BR3/PR′3) as predictor variables: ΔER([R3BH−][HPR′]) = −0.779HA(BR3) − 0.695PA(PR′3) − 1.331 ΔE(BR3/PR′3) + 245.3 kcal/mol. The fitting equation provides quantitative insights into the steric and electronic effects on the thermodynamic aspects of the heterolytic H2‐splitting reactions. The electronic effects are reflected by HA(BR3) and PA(PR′3), and ΔEbcan be significantly influenced by the steric overcrowding. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Molecular dynamics simulation of ionic transport on molten Li–KCl interface
Authors: Duan Xiao‐Hui , Li Jian‐Feng , Zhu Wen‐Jun 
Published: October 2010

AbstractA molecular dynamics study is performed to determine the dynamics and transport properties of the ions on the molten interface between anode metal Li and electrolyte KCl. Radial distribution function of the ionic pair and the behavior of the mean‐square displacement (MSD) as a function of time (t) indicate that KCl and metal Li are in the molten state at 2,200 K in the canonical ensemble. The dynamics of the ionic transport are characterized by studying MSD for the centers of mass of the ions at different temperatures. Diffusion coefficient is evaluated from the linear slope of the MSD (t) function in the range of 0–500 ps. The MSD and diffusion coefficient of the Li+ ions are much larger than those of the Cl− and K+ ions due to the difference in ionic characteristic. The transport process has been dominated by the Li+ ions on the molten interface and the Li+ ions are main charge carriers. The energy barrier of the Li+ ions transporting into the molten KCl is fitted to be 5.28 kcal/mol in the light of the activation model. The electrical conductivity of the Li+ ions transporting into the molten KCl are calculated from the Nernst–Einstein formula to be in the range of 0.2–0.3 S cm−1. The current density resulted from the Li+ ions through the interface are estimated to be an order of 106 A cm−2, which may be the value corresponding to a larger concentration gradient of the Li+ ions. Simulated results at different temperatures show that the diffusion coefficient, conductivity and current density have increased with the temperature. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
A density functional theory study on the Diels‐Alder reactions with vinylallenes as dienes
Authors: Li Zhi‐Ming , Wang Quan‐Rui 
Published: October 2010

AbstractThe Diels‐Alder (DA) reactions of vinylallenes (VA) with ethylenes were investigated using the global electrophilicity and nucleophilicity of the corresponding reactants as global reactivity indexes defined within the conceptual density functional theory. The reactivity and regioselectivity of these reactions were predicted by analysis of the energies, geometries, and electronic nature of the transition‐state structures. In general, substitution by the electron‐accepting acetyl group favors the reaction, whereas substitution by the electron‐releasing methoxy group provides the opposite effect, regardless of being on VA or ethylene. However, the substitution effect in ethylene is apparently greater than that in VA. It has also been disclosed that substitution by electron‐accepting group on both reactants accelerates the reaction, and the reaction may give different regioselectivity from that between VA and acetyl‐substituted ethylene. This has also been verified by our experiments. It seems that the DA reactions with VAs as the diene components can generally be classified as nonpolar asynchronous with the endo product formation (wherever possible) being more pronounced. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Exploring the reciprocal causal relationship between job strain and burnout: A longitudinal study of apparently healthy employed persons
Authors: Melamed Samuel , Armon Galit , Shirom Arie , Shapira Itzhak 
Published: October 2010

AbstractWe used a full‐panel longitudinal design to investigate the hypotheses that changes in the components of the Job Demand‐Control‐Support (JDC‐S) model predict changes in burnout over time, and vice versa. The study was conducted on a multi‐occupational sample of apparently healthy employed men and women (N = 986), followed‐up after 3 years. We found support for both direct and reverse causal relationship between the study variables. Changes over time in the JDC‐S components and changes over time in burnout levels mutually influenced each other. No interactive effects among the JDC‐S components in the prediction of burnout were found. These findings suggest a predominance of the direct casual relationship between work characteristics and burnout compared with the reverse relationship. The findings remained significant even after controlling for depressive symptoms, neuroticism and other potential confounding variables. An explanation for the dynamic association between work characteristics and burnout uncovered here is offered based on the Conservation of Resources (COR) theory. Based on the COR theory, we outline the theoretical implications of our findings and their relevance for efforts to combat burnout. Copyright © 2010 John Wiley & Sons, Ltd.
Surface‐Induced Synthesis and Self‐Assembly of Metal Suprastructures
Authors: Li Shaozhou , Huang Xiao , Li Hai , Cai Hui , Gan Chee Lip , Boey Freddy , Zhang Hua 
Published: October 2010

AbstractA systematic study on the synthesis of a series of self‐assembled suprastructures, such as cubes, stars, belts, and microspheres, of Ag nanoparticles (AgNPs) in borosilicate glassware heavily cleaned with aqua regia is presented. These self‐assembled structures are mostly formed from the crystallographically iso‐oriented AgNPs, and exhibit well‐defined shapes. In regular washed glassware, only Ag nanowires are synthesized. The formation mechanisms of these self‐assembled Ag structures, based on monitoring of their structural evolution in glassware decorated with different molecules, are proposed. This work not only demonstrates that the surface energy of glassware can affect chemical synthesis, but also provides an interesting approach to the shape‐controlled synthesis of novel self‐assembled suprastructures of AgNPs, which could be potentially used as synthesis templates, drug vessels, and microreactors.
Immobilization of urease on dialdehyde porous starch
Authors: Luo Zhigang , Fu Xiong 
Published: October 2010

AbstractDialdehyde porous starch (DPS) was prepared by enzymatic hydrolysis and periodate oxidation. Urease was immobilized on DPS by several techniques including physical adsorption and covalent bonding. Optimum urease immobilization conditions for maximum enzyme activity were shown as following: immobilization pH 6.0, processing time of immobilization 25 h, immobilization temperature 25°C, aldehydic groups content 79.6% and ratio of supporter to urease 1:2 (w/v in g/mL). Temperature optimum of the free and immobilized urease were 60 and 70°C, respectively. The temperature curve of the immoblized urease was wider than that registered for the free urease. After being stored at ambient temperature for 42 days, the immobilized urease retained almost all of the original activity. DPS was found capable of holding the urease enzyme during a repeated cyclic test for ten times. An increase of the Km value for the immobilized urease was found. The foregoing data indicated that DPS is a fine supporter for urease and provided a basis for biosensor or bioreactor development with reduced costs and improved shelf life.
An abstract model of service discovery and binding
Authors: Fiadeiro José Luiz , Lopes Antónia , Bocchi Laura 
Published: October 2010

Abstract
We propose a formal operational semantics for service discovery and binding. This semantics is based on a graph-based representation of the configuration of global computers typed by business activities. Business activities execute distributed workflows that can trigger, at run time, the discovery, ranking and selection of services to which they bind, thus reconfiguring the workflows that they execute. Discovery, ranking and selection are based on compliance with required business and interaction protocols and optimisation of quality-of-service constraints. Binding and reconfiguration are captured as algebraic operations on configuration graphs. We also discuss the methodological implications that this model framework has on software engineering using a typical travel-booking scenario. To the best of our knowledge, our approach is the first to provide a clear separation between service computation and discovery/instantiation/binding, and to offer a formal framework that is independent of the SOA middleware components that act as service registries or brokers, and the protocols through which bindings and invocations are performed.