bluuebunny/crossref_metadata_2025_split huggingface dataset:
Static and dynamic polarizability of C540 fullerene
Authors: Calaminici Patrizia , Carmona‐Espindola Javier , Geudtner Gerald , Köster Andreas M. 
Published: June 2012

AbstractState‐of‐the‐art calculations of static and dynamic polarizabilities of the giant fullerene C540 are presented. These density functional theory calculations have been performed using time‐dependent auxiliary density perturbation theory which was recently implemented in deMon2k (Carmona‐Espíndola et al., JCP 2010, 133, 084102). For the polarizability calculations the local density approximation was used in combination with all‐electron double‐zeta valence polarization basis sets. To gain insight into the trend of these properties as the fullerene size increases the obtained results for C540 are discussed with respect to those obtained for smaller fullerenes such as C60, C70, C180, and C240. All fullerene structures were fully optimized without symmetry constrains. As the cluster size increases the dynamic polarizability strongly increases with respect to the static polarizability. Our analysis shows that static and dynamic polarizabilities per atom increase significantly with fullerene size. Moreover, the increase in the dynamic polarizabilities per atom is larger than for the static ones. © 2012 Wiley Periodicals, Inc.
Atmospheric degradation mechanisms of a simulant organophosphorus pesticide isopropyl methyl methylphosphonate: A theoretical consideration
Authors: Hu Shu‐Xian , Yu Jian‐Guo , Zeng Eddy Y. 
Published: June 2012

AbstractCalculations using density functional theory were performed to explore the mechanisms for atmospheric degradation of isopropyl methyl methylphosphonate (IMMP). The potential energy surface profiles for OH‐initiated reaction of IMMP were constructed, and all possible degradation channels were considered. Rate constants were further calculated using transition state theory. It was established from these calculations that H‐abstractions from alkyl groups have much lower energy barriers than substitutions of alkoxyl groups, and four possible H‐abstraction channels are competitive. Investigations into the secondary reactions under the presence of O2/NO were also performed. It is shown that O2 addition, reaction of peroxide radicals with NO to form RO radicals, and removal of ·RO are the major degradation pathways for alkyl radicals. Four selected products, CH3OP(O)(CH3)OC(O)CH3, CH3OP(O)(O)CH3, (CH3)2CHOP(O)(CH3)OH, and (CH3)2CHOP(O)(CH3)OCHO, are predicted to be the major products in this study. © 2013 Wiley Periodicals, Inc.
Estimating stacking interaction energy using atom in molecules properties: Homodimers of benzene and pyridine
Authors: Zhikol Oleg A. , Shishkin Oleg V. 
Published: June 2012

AbstractAn attempt is presented to infer the stacking interaction energy from the atom in molecules (AIM) properties computed in all critical points of electron density found between interacting molecules. In this study, benzene and pyridine homodimers in coaxial and parallel displaced configurations were used as model structures. We classify the structures and briefly discuss their peculiarities in the AIM theory framework. The maximum absolute error of 2 kcal/mol achieved for 300 potential energy surface point set indicates that a more sophisticated algorithm for estimating atom–atom interactions is needed still. © 2012 Wiley Periodicals, Inc.
Density functional theory study on the interaction between metalloporphyrins and NH3
Authors: Cao Zhenfeng , Chen Qibin , Lu Yunxiang , Liu Honglai , Hu Ying 
Published: June 2012

AbstractThe binding behaviors of eight bivalent metalloporphyrins (MPs) (MZn, Mg, Cu, Mn, Fe, Co, Ni, and Cd) with NH3 were investigated by density functional theory. For both MPs and corresponding complexes MPs‐NH3, good linear correlations are found between the partial charge on metal M and that on atom N (nitrogen of porphyrin) as well as the MN bond length. Natural population and frontier orbital analysis demonstrate that charge transfer in CoP‐NH3 is much easier and greater. As a consequence of the charge transfer and the hybridization of molecular energy levels, striking disparities of electronic properties of MPs‐NH3 are observed. Particularly, a modest linear relationship is obtained between the magnitude of charge transfer and the binding energy. The much greater Fukui functions of CoP, together with its larger binding strength, suggest that CoP is more favorable to the interaction with NH3, which might be a promising sensing material to response NH3. © 2013 Wiley Periodicals, Inc.
The detection of high‐mass aliphatics in petroleum by matrix‐assisted laser desorption/ionisation mass spectrometry
Authors: Lorente Esther , Berrueco Cesar , Herod Alan A , Millan Marcos , Kandiyoti Rafael 
Published: June 2012

RATIONALEThe development of simplified procedures for isolating high‐mass alkanes present in crude oils is described. The new procedures, which bypass the sample recovery step with hot toluene in the conventional alkane‐isolation procedure, also provide an effective sample preparation route, prior to analysis by matrix‐assisted laser desorption/ionisation mass spectrometry (MALDI‐MS).METHODSUrea‐alkane adducts are formed by mixing sample and urea solutions on chromatographic paper or silica‐coated plates. Unreacted hydrocarbons are removed by developing the plates with chloroform. In a second development with water, adducts are broken up in situ and the liberated urea removed, leaving bands of isolated alkanes behind. For MALDI‐MS, strips of paper/plates, carrying the isolated alkanes, are fixed on metal target plates. The samples are treated with matrix (AgNO3) and analysed by MALDI‐MS.RESULTSThe observed signal represents silver ion adducts of the isolated alkanes. Silver appears to work without much fragmentation and to generate whole silver adduct ions. Much improved MALDI‐MS detection sensitivity and a wider range of masses was observed when samples were ablated from paper/plate surfaces, than by ablation from bulk samples spread over a smooth surface – the conventional method. Chromatographic paper gave better resolution and a broader range of masses than silica‐coated plates.CONCLUSIONSThe analytical sequences have been confirmed using standard alkanes (C20–C60) and Polywax. The proposed procedures enhanced the sensitivity and detection range of the MS analysis. The method was useful in detecting n‐alkanes to m/z 1500 (C100) and required relatively small quantities of sample and reagents. It provides a promising qualitative analysis route for the rapid isolation and reliable determination of alkanes in crude oils. Copyright © 2012 John Wiley & Sons, Ltd.
A Pilot Study Examining the Effects of Kouk Sun Do on University Students with Anxiety Symptoms
Authors: Kim Jong‐Ho , Yang Heewon , Schroeppel Stephen 
Published: June 2012

AbstractThe effects of Kouk Sun Do (KSD), a mind–body exercise on mental health in university students, were investigated in this pilot study. University students (N = 30) with self‐reported anxiety symptoms were randomly assigned to either the treatment group or the waiting list control group. Eighteen participants (N = 18; seven in the treatment group and 11 in the waiting list control group) completed a pre‐test and a post‐test, and 12 participants dropped out before or during the intervention. Ten 70‐min KSD exercise sessions were conducted three times per week over a 4‐week period. Trait anxiety, depressive symptoms and general self‐efficacy in coping with stress were measured with the pre‐test and the post‐test. Qualitative data were collected using open‐ended questions regarding benefits of KSD at the last session. A two (group) by two (time) repeated‐measure analysis of variance was used to analyse the data. Trait anxiety and depressive symptoms decreased whereas general self‐efficacy increased over a 4‐week period. The treatment group had significantly reduced trait anxiety and depressive symptoms compared with the control group across time. Qualitative data provided support that the self‐induced relaxation effects of KSD may lead to reduced anxiety. Copyright © 2012 John Wiley & Sons, Ltd.
Feasibility and Effectiveness of a Chen‐style Tai Chi Programme for Stress Reduction in Junior Secondary School Students
Authors: Lee Linda Y. K. , Chong Yeuk Lan , Li Ngai Yin , Li Man Chung , Lin Lai Na , Wong Lee Yi , Wong Brian Kit , Yip Wing Ping , Hon Cho Hang , Chung Pui Kuen , Man Shuk Yee 
Published: June 2012

AbstractStress is common in junior secondary school students (JSSS). This study aimed to determine the feasibility and effectiveness of a Chen‐style Tai Chi programme for stress reduction in JSSS. A non‐equivalent pre‐test/post‐test control group design was adopted, and a convenience sample of 69 JSSS was recruited. The experimental group (n = 32) joined a Chen‐style Tai Chi programme, which included 10 sessions of 80‐minute Tai Chi training (one session per week). The control group (n = 37) proceeded with self‐study. Participants' stress levels were assessed using the Perceived Stress Scale. Feasibility was determined as the percentage of participants completing and attending the programme. Effectiveness was measured as the significant difference in changes in stress levels before and after the intervention between the two groups. Results preliminarily supported that the programme was feasible for JSSS. Completion rate was 100%, and attendance rate was 90%. However, no significant difference was noted in changes in stress levels before and after the intervention between the two groups. The potential health benefits of Tai Chi could not be detected owing to the restrictions imposed by the research setting and study limitations. The present study represents initial efforts in this direction and serves as reference for future study. Copyright © 2012 John Wiley & Sons, Ltd.
Reoxidation of Al‐Killed Steel by Ca(OH)2 in the High Basicity Slag
Authors: Jiang Fang , Liu Yan , Xie You , Cheng Guoguang 
Published: June 2012

AbstractIn the present work, reoxidation of Al‐killed steel by Ca(OH)2 in high basicity slag was investigated by using laboratory experiments at 1873 K in MgO crucibles with various amount of Ca(OH)2 addition into slag. The CaO–SiO2–Al2O3–MgO–Ca(OH)2 slags were used to study the effect of Ca(OH)2 on total oxygen content, aluminum loss, and FeO content in the slag. It was shown that total oxygen content decreased with the time when no Ca(OH)2 was added into the slag, but it first increased and then decreased with the time when the addition of Ca(OH)2 was made. Moreover, aluminum loss and FeO content in the slag increased with increasing Ca(OH)2 content.
Maternal phenylketonuria: low phenylalaninemia might increase the risk of intra uterine growth retardation
Authors: Teissier Raphaël , Nowak Emmanuel , Assoun Murielle , Mention Karine , Cano Aline , Fouilhoux Alain , Feillet François , Ogier Hélène , Oger Emmanuel , de Parscau Loïc ,   On behalf of the AFDPHE (Association Française pour le Dépistage et la Prévention des Handicaps de l'Enfant)
Published: June 2012

AbstractBackgroundMalformations and mental retardation in the offspring of women with Phenylketonuria (PKU) can be prevented by maintaining maternal blood Phenylalanine (PHE) within a target range (120–300 μmol/L) through a PHE‐restricted diet. In a former French study, a high and unexpected proportion of intra uterine growth retardation (IUGR) has been reported. Guidelines have been proposed to all French centres caring for maternal PKU since 2002.ObjectiveTo confirm IUGR and investigate its causes. The other goals were to assess the follow‐up of these pregnancies based on the new guidelines and the pertinence of these recommendations.DesignClinical, biological and ultrasound data of all pregnancies in PKU women in France, from 2002 to 2007 were retrospectively analyzed.ResultsData from 115 pregnancies in 86 women with PKU were collected. Ninety percent of women had been informed of the risk of maternal PKU in the absence of a strict diet during pregnancy, 88 % of women had started a diet before conception, and 45 % of infants were born small for gestational age (birth length and/or weight ≤−2 SD). PHE intakes were lower in the group with IUGR from the fifth to the eighth month of pregnancy and duration of time spent at <120 μmol/L during pregnancy was associated with a higher risk of IUGR.ConclusionHyperphenylalaninemia (HPA) is not the only risk factor for IUGR; PHE lower than 120 μmol/L could also be associated with the IUGR occurence. Even if the monitoring of these pregnancies has been improved since the initiation of guidelines, we would like to stress on the importance of the dietary aspect of the disease.
Partially Hydrolyzed Guar Gums Reduce Dietary Fatty Acid and Sterol Absorption in Guinea Pigs Independent of Viscosity
Authors: Santas Jonathan , Espadaler Jordi , Cuñé Jordi , Rafecas Magda 
Published: June 2012

AbstractThis study investigated the effect of two partially hydrolyzed guar gums (PHGG) on fatty acid and sterol excretion. PHGG were obtained by chemical hydrolysis of guar gum (GG) with H2O:EtOH (1:1) at 100 °C for 1 h (PHGG1) or 2 h (PHGG2). The viscosity of the PHGG in a 1 % (w/v) aqueous solution corresponded to that of a pseudoplastic fluid and was higher for PHGG1 than PHGG2. Guinea pigs (n = 8 per group) were fed high fat diets (17/100 g) that contained 12/100 g of cellulose, PHGG1, or PHGG2 for 4 weeks. Despite the differences in viscosity, the two PHGG exerted similar physiological effects. Compared to the control cellulose group, the body weight gain was lower in animals fed PHGG, although no effect on food consumption was observed. PHGG increased the excretion of fatty acids and neutral sterols, but not bile acids. Consumption of PHGG did not alter the fecal fatty acid profile, while intestinal bioconversion of sterols tended to increase in response to PHGG2. A reduction in the viscosity within the range tested did not correlate with losses in the hypocholesterolemic capacity of PHGG as both were effective in reducing plasma cholesterol. Thus, we conclude that the chemical hydrolysis of guar gum renders the gum suitable for inclusion in food products without significantly altering its beneficial health effects.
The effect of variable thermal diffusivity on kinematic models of subduction
Authors: Maierová P. , Chust T. , Steinle‐Neumann G. , Čadek O. , Čížková H. 
Published: June 2012

We examine the influence of variable thermal properties on the thermal state of a subducting slab in the upper mantle and the transition zone by combining a kinematic slab model with models of thermal conductivity. Thermal diffusivity and conductivity models for major mantle minerals in the MgO‐SiO2 system are developed based on experimental measurements on these minerals at high pressure and temperature. The models show significantly higher thermal conductivity for stishovite and clinopyroxene compared to the Mg2SiO4 polymorphs and majorite garnet. In our subduction model we consider scenarios with a differentiated slab (basalt–harzburgite–pyrolite) in a pyrolite mantle and uniform composition for both the slab and the mantle (pyrolite or a pure Mg2SiO4‐based system). The role of highly conductive pyroxene is examined by taking it into account in some models and replacing it in others with majorite garnet. This choice has a strong influence on the thermal state of the slab, shifting the depth of the −1000 K temperature anomaly by as much as 100 km. This is caused by faster cooling of the plate at the surface and thermal insulating effects once subducted. Temperature differences between models with variable thermal diffusivity and those with constant parameters can reach ∼125 K, i.e. 10% of total thermal anomalies of the slab relative to an average geotherm. Taking into account the stable mineral phases we evaluate density variations between different models and find that variable thermal diffusivity results in a modest increase of negative buoyancy of the slab.
Bounce‐averaged diffusion coefficients due to resonant interaction of the outer radiation belt electrons with oblique chorus waves computed in a realistic magnetic field model
Authors: Orlova Ksenia G. , Shprits Yuri Y. , Ni Binbin 
Published: June 2012

We present the results of calculations of the bounce‐averaged pitch angle, mixed, and momentum diffusion coefficients in a dipole and two realistic field models (the T01s model for quiet and storm conditions). We consider resonant interactions of the outer radiation belt electrons with oblique chorus waves. We demonstrate that on the dayside, the use of a realistic magnetic field versus a dipole field only makes a significant difference for small equatorial pitch angles at energies larger than E = 1 MeV. On the nightside, the differences between the scattering rates calculated in the Tsyganenko and dipole models can reach several orders of magnitude at various equatorial pitch angles for electrons with E ≥ 0.5 MeV. The most significant changes in the scattering rates computed in the realistic and dipole magnetic fields occur during the geomagnetically active conditions. On the nightside, for E ≥ 0.5 MeV, the diffusion coefficients calculated in the Tsyganenko field show significant scattering near the edge of the loss cone that can produce loss of electrons to the atmosphere, while in the dipole model there is no scattering at small equatorial pitch angles. Our computations in the realistic field show that resonant interactions between electrons with E ≤ 1 MeV and chorus waves can be an effective net loss mechanism on both the dayside and the nightside. To explain the differences in the scattering rates associated with a change in the magnetic field model, we present the contribution of various resonant harmonics to the diffusion and examine the changes in the resonance condition.
Solar forcing of Florida Straits surface salinity during the early Holocene
Authors: Schmidt Matthew W. , Weinlein William A. , Marcantonio Franco , Lynch‐Stieglitz Jean 
Published: June 2012

Previous studies showed that sea surface salinity (SSS) in the Florida Straits as well as Florida Current transport covaried with changes in North Atlantic climate over the past two millennia. However, little is known about earlier Holocene hydrographic variability in the Florida Straits. Here, we combine Mg/Ca‐paleothermometry and stable oxygen isotope measurements on the planktonic foraminifera Globigerinoides ruber (white variety) from Florida Straits sediment core KNR166–2 JPC 51 (24° 24.70′ N, 83° 13.14′ W, 198 m deep) to reconstruct a high‐resolution (∼25 yr/sample) early to mid Holocene record of sea surface temperature and δ18OSW (a proxy for SSS) variability. After removing the influence of global δ18OSW change due to continental ice volume variability, we find that early Holocene SSS enrichments are associated with increased evaporation/precipitation ratios in the Florida Straits during periods of reduced solar forcing, increased ice rafted debris in the North Atlantic and the development of more permanent El Niño–like conditions in the eastern equatorial Pacific. When considered with previous high‐resolution reconstructions of Holocene tropical atmospheric circulation changes, our results provide evidence that variations in solar forcing over the early Holocene had a significant impact on the global tropical hydrologic cycle.
Effect of mass transfer on the oxygen reduction reaction catalyzed by platinum dendrimer encapsulated nanoparticles
Authors: Dumitrescu Ioana , Crooks Richard M. 
Published: June 2012

Here we report on the effect of the mass transfer rate (
k
t
) on the oxygen reduction reaction (ORR) catalyzed by Pt dendrimer-encapsulated nanoparticles (DENs) comprised of 147 and 55 atoms (Pt
147
and Pt
55
). The experiments were carried out using a dual-electrode microelectrochemical device, which enables the study of the ORR under high
k
t
conditions with simultaneous detection of H
2
O
2
. At low
k
t
(0.02 to 0.12 cm s
-1
) the effective number of electrons involved in ORR,
n
eff
, is 3.7 for Pt
147
and 3.4 for Pt
55
. As
k
t
is increased, the mass-transfer-limited current for the ORR becomes significantly lower than the value predicted by the Levich equation for a 4-electron process regardless of catalyst size. However, the percentage of H
2
O
2
detected remains constant, such that
n
eff
barely changes over the entire
k
t
range explored (0.02 cm s
-1
). This suggests that mass transfer does not affect
n
eff
, which has implications for the mechanism of the ORR on Pt nanoparticles. Interestingly, there is a significant difference in
n
eff
for the two sizes of Pt DENs (
n
eff
= 3.7 and 3.5 for Pt
147
and Pt
55
, respectively) that cannot be assigned to mass transfer effects and that we therefore attribute to a particle size effect.
Accurate protein structure modeling using sparse NMR data and homologous structure information
Authors: Thompson James M. , Sgourakis Nikolaos G. , Liu Gaohua , Rossi Paolo , Tang Yuefeng , Mills Jeffrey L. , Szyperski Thomas , Montelione Gaetano T. , Baker David 
Published: June 2012

While information from homologous structures plays a central role in X-ray structure determination by molecular replacement, such information is rarely used in NMR structure determination because it can be incorrect, both locally and globally, when evolutionary relationships are inferred incorrectly or there has been considerable evolutionary structural divergence. Here we describe a method that allows robust modeling of protein structures of up to 225 residues by combining

,
13
C, and
15
N backbone and
13
C
β
chemical shift data, distance restraints derived from homologous structures, and a physically realistic all-atom energy function. Accurate models are distinguished from inaccurate models generated using incorrect sequence alignments by requiring that (
i
) the all-atom energies of models generated using the restraints are lower than models generated in unrestrained calculations and (
ii
) the low-energy structures converge to within 2.0 Å backbone rmsd over 75% of the protein. Benchmark calculations on known structures and blind targets show that the method can accurately model protein structures, even with very remote homology information, to a backbone rmsd of 1.2–1.9 Å relative to the conventional determined NMR ensembles and of 0.9–1.6 Å relative to X-ray structures for well-defined regions of the protein structures. This approach facilitates the accurate modeling of protein structures using backbone chemical shift data without need for side-chain resonance assignments and extensive analysis of NOESY cross-peak assignments.