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Christoph Schran, Felix Uhl, Jörg Behler, Dominik Marx
The design of accurate helium-solute interaction potentials for the simulation of chemically complex molecules solvated in superfluid helium has long been a cumbersome task due to the rather weak but strongly anisotropic nature of the interactions. We show that this challenge can be met by using a combination of an effective pair potential for the He-He interactions and a flexible high-dimensional neural network potential (NNP) for describing the complex interaction between helium and the solute in a pairwise additive manner...
March 14, 2018: Journal of Chemical Physics
Christian J Burnham, Zdenek Futera, Niall J English
The force-matching method has been applied to parameterise an empirical potential model for water-water and water-hydrogen intermolecular interactions for use in clathrate-hydrate simulations containing hydrogen guest molecules. The underlying reference simulations constituted ab initio molecular dynamics (AIMD) of clathrate hydrates with various occupations of hydrogen-molecule guests. It is shown that the resultant model is able to reproduce AIMD-derived free-energy curves for the movement of a tagged hydrogen molecule between the water cages that make up the clathrate, thus giving us confidence in the model...
March 14, 2018: Journal of Chemical Physics
Marlene J Schulte, Jody L Clasey, Bradley S Fleenor, Haley C Bergstrom
There are conflicting suggestions regarding the most valid resistance (3-5% of body weight) to use for the critical power (CP) 3-min all-out (CP3min ) test to estimate CP and anaerobic work capacity (AWC). The purpose of this study was to determine if the CP and AWC estimates from the CP3min test were affected by the percentage of body weight used to set the resistance on a Monark cycle ergometer. Ten recreationally trained participants (mean ± SD: Age: 22.2 ± 2.2 yrs.) completed the CP3min test at resistances of 4...
2018: International Journal of Exercise Science
M Merced Montero-Campillo, Ibon Alkorta, José Elguero
A set of complexes L2HB···BeX2 (L = CNH, CO, CS, N2, NH3, NCCH3, PH3, PF3, PMe3, OH2; X = H, F) containing a boron-beryllium bond is described at the M06-2X/6-311+G(3df,2pd)//M062-2X/6-31+G(d) level of theory. In this quite unusual bond, boron acts as a Lewis base and beryllium as a Lewis acid, reaching binding energies up to -283.3 kJ/mol ((H2O)2HB···BeF2). The stabilization of these complexes is possible thanks to the -donor role of the L ligands in the L2HB···BeX2 structures and the powerful acceptor nature of beryllium...
March 14, 2018: Journal of Physical Chemistry. A
Reka Horvath, Gyorgy Hantal, Sylvain Picaud, Milán Szőri, Pal Jedlovszky
The adsorption of methylamine at the surface of amorphous ice is studied at various temperatures, ranging from 20 K to 200 K, by grand canonical Monte Carlo simulations under conditions that are characteristic to the interstellar medium (ISM). The results are also compared with those obtained earlier on crystalline (Ih) ice. We found that methylamine has a strong ability of being adsorbed on amorphous ice, involving also multilayer adsorption. The decrease of the temperature leads to a substantial increase of this adsorption ability, thus, considerable adsorption is seen at 20-50 K even at bulk gas phase concentrations that are comparable with that of the ISM...
March 14, 2018: Journal of Physical Chemistry. A
Aaron M Thomas, Michael Lucas, Long Zhao, Jerid Liddiard, Ralf I Kaiser, Alexander M Mebel
The crossed molecular beams technique was utilized to explore the formation of three isomers of resonantly stabilized (C5 H3 ) radicals along with their d2 -substituted counterparts via the bimolecular reactions of singlet/triplet dicarbon [C2 (X1 Σ/a3 Πu )] with methylacetylene [CH3 CCH(X1 A1 )], d3 -methylacetylene [CD3 CCH(X1 A1 )], and 1-butyne [C2 H5 CCH(X1 A')] at collision energies up to 26 kJ mol-1 via chemically activated singlet/triplet C5 H4 /C5 D3 H and C6 H6 intermediates. These studies exploit a newly developed supersonic dicarbon [C2 (X1 Σ/a3 Πu )] beam generated via photolysis of tetrachloroethylene [C2 Cl4 (X1 Ag )] by excluding interference from carbon atoms, which represent the dominating (interfering) species in ablation-based dicarbon sources...
March 14, 2018: Physical Chemistry Chemical Physics: PCCP
Wei Zhang, Guang Xu, Ying Cheng, Lingjuan Chen, Quan Huo, Suyan Liu
The sulfide catalyst is a subject of great interest in developing a MgH2 system as a potential hydrogen storage medium. In this work, FeS2 micro-spheres were successfully prepared by the surfactant-assisted solvothermal method, and later were ball milled with MgH2 to fabricate the MgH2 -16.7 wt% FeS2 composite. FeS2 addition could dramatically improve both the hydrogenation and dehydrogenation kinetics, and lower the dehydrogenation temperature of MgH2 as well. The MgH2 -16.7 wt% FeS2 composite could absorb 3...
March 14, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Wouter J Heerink, A Millad Solouki, Rozemarijn Vliegenthart, Simeon J S Ruiter, Egbert Sieders, Matthijs Oudkerk, Koert P de Jong
OBJECTIVES: To study the ratio of ablation zone volume to applied energy in computed tomography (CT)-guided radiofrequency ablation (RFA) and microwave ablation (MWA) in patients with hepatocellular carcinoma (HCC) in a cirrhotic liver and in patients with colorectal liver metastasis (CRLM). METHODS: In total, 90 liver tumors, 45 HCCs in a cirrhotic liver and 45 CRLMs were treated with RFA or with one of two MWA devices (MWA_A and MWA_B), resulting in 15 procedures for each tumor type, per device...
March 13, 2018: European Radiology
Francesco Manzoni, Ulf Ryde
We have calculated relative binding affinities for eight tetrafluorophenyl-triazole-thiogalactoside inhibitors of galectin-3 with the alchemical free-energy perturbation approach. We obtain a mean absolute deviation from experimental estimates of only 2-3 kJ/mol and a correlation coefficient (R2 ) of 0.5-0.8 for seven relative affinities spanning a range of up to 11 kJ/mol. We also studied the effect of using different methods to calculate the charges of the inhibitor and different sizes of the perturbed group (the atoms that are described by soft-core potentials and are allowed to have differing coordinates)...
March 13, 2018: Journal of Computer-aided Molecular Design
Prajakta Rajaram Parab, K Alexander Heufer, Ravi Xavier Fernandes
Isopentanol is a potential next-generation biofuel for future applications to Homogeneous Charge Compression Ignition (HCCI) engine concepts. To provide insights into the combustion behavior of isopentanol, especially to its auto-ignition behavior which is linked both to efficiency and pollutant formation in real combustion systems, detailed quantum chemical studies for crucial reactions are desired. H-Abstraction reaction rates from fuel molecules are key initiation steps for chain branching required for auto-ignition...
March 13, 2018: Physical Chemistry Chemical Physics: PCCP
Kanokwan Kongphitee, Kritapon Sommart, Thamrongsak Phonbumrung, Thidarat Gunha, Tomoyuki Suzuki
Objective: This study was conducted to assess the effects of replacing rice straw with different proportions of cassava pulp on growth performance, feed intake, digestibility, rumen microbial population, energy partitioning and efficiency of metabolizable energy utilization in beef cattle. Methods: Eighteen yearling Thai native beef cattle (Bos indicus) with an average initial body weight of 98.3 ± 12.8 kg were allocated to one of three dietary treatments and fed ad libitum for 149 days in a randomized complete block design...
March 13, 2018: Asian-Australasian Journal of Animal Sciences
Betul Sen, Aysun Şavk, Fatih Sen
Dimethylamine borane (DMAB) has been considered as one of the important hydrogen sources with a simple process by the help of the efficient catalyst. For this purpose, herein, platinum nanoparticles (Pt NPs), placed inside carbon black hybrid (Pt NPs@CBH), activated carbon (Pt NPs@AC) and Vulcan carbon (Pt NPs@VC), have been prepared as highly monodisperse catalysts for dehydrogenation reactions of DMAB at room temperature. The morphological and physical structure of the monodisperse catalysts have been identified by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) etc...
March 3, 2018: Journal of Colloid and Interface Science
Michael Lucas, Aaron M Thomas, Ralf I Kaiser, Eugene K Bashkirov, Valeriy N Azyazov, Alexander Moiseevich Mebel
We explored the elementary reaction of atomic carbon (C;3 Pj ) with pyridine (C5 H5 N; X1 A1 ) at a collision energy of 34 ± 4 kJ mol-1 utilizing the crossed molecular beams technique. Forward-convolution fitting of the data was combined with high-level electronic structure calculations and statistical (RRKM) calculations on the triplet C6 H5 N potential energy surface (PES). These investigations reveal that the reaction dynamics are indirect and dominated by large range reactive impact parameters leading via barrier-less addition to the nitrogen atom and to two chemically non-equivalent 'aromatic' carbon-carbon bonds forming three distinct collision complexes...
March 12, 2018: Journal of Physical Chemistry. A
Gro Askgaard, Janne S Tolstrup, Mette S Kjær, David A Leon
AIMS: Alcoholic liver cirrhosis is usually preceded by years of heavy drinking. We investigated whether the risk of alcoholic liver cirrhosis increases as the number of hospital contacts with alcohol problems goes up. METHODS: This was a supplementary analysis on a nationwide register-based cohort study. All patients in Denmark with an initial hospital contact with alcohol problems (alcohol intoxication, harmful alcohol use or alcohol dependence) 1998-2002, free of liver disease, were followed for diagnosis of alcoholic liver cirrhosis...
March 1, 2018: Scandinavian Journal of Public Health
Junyi Zhao, Huafeng Chen, Wenxin Li, Xiaoyu Jia, Xuequan Zhang, Dirong Gong
Ligands N-(dialkyl or arylphosphino)-(2,2'-bipyridin)-6-amine (L1, aryl = Ph; L2, alkyl =t Bu; L3, alkyl = adamantyl (Ad)) as well as the corresponding oxidized N-(2,2'-bipyridin-6-yl)- P, P-dialkyl or aryl phosphinic amide (L4, aryl = Ph; L5, alkyl =t Bu; L6, alkyl = Ad) congeners were designed and coordinated to cobalt dichloride. The structures of formed complexes were characterized by IR and elemental analyses, as well as characterizations of the X-ray diffractions for complexes Co4 and Co6, which revealed the cobalt center is expectedly pentacoordinated in a distorted trigonal bipyramidal configuration with a prolonged Co-O(═P) bond ...
March 12, 2018: Inorganic Chemistry
M Crawford Andrews, Ping Peng, Amit Rajput, Anthony F Cozzolino
Carboxamidines functionalized with either a spiropyran or fulgimide photoswitch were prepared on multigram scales. The thermal, electrochemical, and photochemical ring isomerizations of these compounds were studied and the results compared with related systems. The photochemical isomerisations were found to be reversible and could be followed by1 H NMR and UV-vis spectroscopy. The spiropyran/merocyanine couple was thermally active and an activation enthalpy of 116 kJ mol-1 was measured for ring-opening. These measurements yielded an enthalpy difference of 25 kJ mol-1 between the open and closed states which is consistent with DFT calculations...
March 12, 2018: Photochemical & Photobiological Sciences
D Mihrin, P W Jakobsen, A Voute, L Manceron, R Wugt Larsen
The high-resolution terahertz absorption spectrum of the large-amplitude intermolecular donor librational band ν of the homodimer (HCN)2 has been recorded by means of long-path static gas-phase Fourier transform spectroscopy at 207 K employing a highly brilliant electron storage ring source. The rovibrational structure of the ν band has the typical appearance of a perpendicular type band of a Σ-Π transition for a linear polyatomic molecule. The generated terahertz spectrum is analyzed employing a standard semi-rigid linear molecule Hamiltonian, yielding a band origin ν0 of 119...
March 12, 2018: Physical Chemistry Chemical Physics: PCCP
Christina Kjær, James M Lisy, Steen Brøndsted Nielsen
Congo Red (CR) is an azo dye that is negatively charged in aqueous solutions. Here we report on the intrinsic electronic properties of CR dianions from mass spectroscopy experiments on bare dianions and their complexes with betaine (B). As betaine is a zwitterion, it possesses a large dipole moment and is a good reporter on the sensitivity of CR to microenvironmental changes. Photoexcitation of CR2- in the visible region resulted in several fragment ions after absorption of at least three photons, with major fragmentation routes due to breakage of one or both C-NN bonds, one azo linkage, and/or the bonds to sulfite...
March 12, 2018: Journal of Physical Chemistry. A
Lin Zhu, Ziliang Chen, Yun Song, Pei Wang, Yingchang Jiang, Le Jiang, Yong-Ning Zhou, Linfeng Hu
Cationic doping has been regarded as an effective strategy to improve the electrochemical performance of transition metal composites for lithium ion batteries (LIBs). Herein, we report manganese doped cobalt nitrides (Mn0.33 Co0.67 N) as a novel anode material for LIBs with a high reversible capacity close to 900 mA h g-1 after 150 cycles at a current density of 0.5 A g-1 , which is superior to 749 mA h g-1 of undoped CoN. The most fascinating performance of Mn0.33 Co0.67 N is the rate capability, in which 91% of capacity is maintained when the current density increases ten-fold from 0...
March 12, 2018: Nanoscale
Kai-Min Yang, Fu-Lan Hsu, Chih-Wei Chen, Chin-Lin Hsu, Ming-Ching Cheng
In this study, the effects of roasting camellia (Camellia oleifera Abel.) seed oils at different temperatures (65°C, 100°C, 120°C, and 140°C) on the oxidative stability and composition of the oils were investigated. The results showed that, in terms of the quality of the oils, the roasting temperature influenced the total phenolic content (which ranged from 1.64~2.45 GAE mg/g for the different oils) and total flavonoid content (which ranged from 0.36~0.45 QE mg/g for the different oils), while the fatty acid profile and tocopherol content were not influenced by the roasting temperature...
March 9, 2018: Journal of Oleo Science
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