bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on fabrication, characterization, and metal extraction using metal chelating nonwoven nanofiber mats of poly(vinyl alcohol) and sodium alginate blends
Authors: Rathna G.V.N. , Birajdar Mallinath S. , Bhagwani Manish , Paul V.L. 
Published: July 2012

AbstractPoly(vinyl alcohol) and sodium alginate blends with and without the metal chelate, bis(2,4,4‐trimethylpentyl)phosphinic acid were prepared in various compositions and fabricated to stable nanofibers and films to evaluate their efficacy for metals adsorption and desorption. Surface morphology of the nanofibers was characterized by scanning electron microscopy. The solution properties and variation in content of sodium alginate in the feed mixture have influenced morphology of nanofibers. However, influence of bis(2,4,4‐trimethylpentyl)phosphinic acid was insignificant. The films and nanofibers were characterized using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermo gravimetric analysis, and X‐ray diffraction to understand compatibility between polymers, thermal stability, decomposition temperature, and variations in crystallinity. Metal adsorption studies for nanofiber mats comprising bis(2,4,4‐trimethylpentyl)phosphinic acid were demonstrated using copper (II), cobalt(II), and nickel(II) salts. The nanofibers adsorbed more copper (363 mg/g) when compared with films (105 mg/g). Nanofiber mats immobilized with bis(2,4,4‐trimethylpentyl)phosphinic acid adsorbed copper in greater magnitude (497 mg/g) than nanofiber mats without bis(2,4,4‐trimethylpentyl)phosphinic acid (363 mg/g). However, adsorption of cobalt and nickel was very low to be detected. The metal adsorption and desorption studies were also confirmed by energy dispersive X‐ray spectroscopy. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Hybrid amphiphilic block copolymers containing polyhedral oligomeric silsesquioxane: Synthesis, characterization, and self‐assembly in solutions
Authors: Yang Cangjie , Deng Yuanming , Zeng Birong , Yuan Conghui , Chen Min , Luo Weiang , Liu Jie , Xu Yiting , Dai Lizong 
Published: July 2012

AbstractIn this article, the amphiphilic block copolymers containing polyhedral oligomeric silsesquioxane (POSS), namely PMAPOSS‐b‐PAA and PMAPOSS‐b‐P(AA‐co‐St), were synthesized consecutively by reversible addition–fragmentation chain transfer and selective hydrolysis, and characterized by 1H NMR, 13C NMR, Fourier transform infrared spectroscopy and gel permeation chromatography. In the presence of the nearly gradient styrene distribution along the hydrophilic block with a feed molar ratio of tert‐butyl acrylate (tBA) to St being 10/1, patterned core‐corona nanoparticles (NPs) were formed from the mixture of good/selective solvents (THF/water) by a simple evaporation process at room temperature. With the extending of the co‐block length, the self‐assembled NPs exhibited phase separation behavior of spheres‐dispersed, onion‐like and onion‐cluster hierarchical structures in turn. However, while a change in the feed molar ratio occurred, it resulted in the formation of typical core‐shell micelles (20/1, tBA/St) and disordered particles (5/1, tBA/St), respectively. Furthermore, the self‐assembly behavior of PMAPOSS‐b‐P(AA‐co‐St) in DMF was investigated, which showed that it could perform a mixture morphology of well‐dispersive sphere micelles and large aggregate of micelles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Synthesis and characterization of thiol–ene functionalized siloxanes and evaluation of their crosslinked network properties
Authors: Cole Megan A. , Bowman Christopher N. 
Published: July 2012

AbstractThree types of linear thiol‐functionalized siloxane oligomers and three types of ene‐functionalized oligomers were synthesized and subsequently photopolymerized. Within each type of thiol‐functionalized oligomer, the ratio of mercaptan repeat units to nonreactive phenyl repeat units was varied to manipulate both the crosslink density and the degree of secondary interactions through π–π stacking. Similarly, the repeat units of the three ene‐functionalized oligomers are composed of allyl‐functional monomers, benzene‐functional monomers, and octyl‐functional monomers in varying ratios of benzene:octyl but with a constant fraction of allyl moieties. The structural composition of the siloxane oligomers plays a pivotal role in the observed material properties of networks formed through thiol–ene photopolymerization. Networks with a high concentration of thiol functionalities exhibit higher rubbery moduli, ultimate strengths, and Young's moduli than networks with lower thiol concentrations. Moreover, the concentration of functionalities capable of participating in secondary interactions via hydrogen bonding or π–π stacking directly impacts the network glass transition temperature and elasticity. The combination of low crosslink density and high secondary interactions produces networks with the greatest toughness. Finally, the fraction of octyl repeats correlates with the hydrophobic nature of the network. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Highly active and easily accessible catalysts for vinyl polymerization of norbornene obtained by oxidative addition of salicylaldimine ligands to bis(1,5‐cyclooctadiene)nickel(0) and methylaluminoxane
Authors: Raspolli Galletti Anna Maria , Hayatifar Mohammad 
Published: July 2012

AbstractHighly active, cheap, and easy to synthesize catalytic systems, obtained in situ by the oxidative addition of salicylaldimine ligands to bis(1,5‐cyclooctadiene)nickel(0) and activated by methylaluminoxane (MAO), are now reported for the vinyl polymerization of norbornene. Their activity resulted mainly influenced by the nature of the substituents present both on the phenolate moiety and on the N‐aryl ring as well as the content of free trimethylaluminum (TMA) present in the commercial MAO. In particular, the maximum activity, up to about 78,000 kg polynorbornene/mol Ni × h, was ascertained when 3,5‐dinitro‐N‐(2,6‐diisopropylphenyl)salicylaldimine ligand was adopted in conjunction with Ni(cod)2 and TMA‐depleted MAO. This remarkable performance, to the best of our knowledge, the highest never reported working in toluene instead of chlorinated aromatics, was reached adopting this more sustainable reaction medium. The influence of the main reaction parameters such as reaction time, temperature, monomer/Ni, and Al/Ni molar ratios on the catalytic performances and polymer characteristics was studied as well. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Sublimation Properties of Pentaerythritol Tetranitrate Single Crystals Doped with Its Homologs
Authors: Bhattacharia Sanjoy K. , Maiti Amitesh , Gee Richard H. , Weeks Brandon L. 
Published: July 2012

AbstractPentaerythritol tetranitrate (PETN) is a secondary explosive used extensively in military and commercial applications. Coarsening of PETN during long‐term storage changes the physical properties such as surface area and particle morphology which are important factors in initiation and performance. Doping of impurities was proposed to slow the coarsening process since impurities were shown to modify both the kinetic and thermodynamic properties. In this paper, we discuss how doping of PETN with its homologs of dipentaerythritol hexanitrate (diPEHN) and tripentaerytritol octanitrate (triPEON) affect kinetic and thermodynamic parameters. Pure and homolog doped PETN single crystals were prepared by solvent evaporation in acetone at room temperature. Doping concentrations for this study were 1000 ppm, 5000 ppm, and 10000 ppm. Activation energy and vapor pressure of pure and doped PETN single crystals were obtained from thermogravimetric analysis data.
On the diffusion of NV defects in diamond
Authors: Pinto H. , Jones R. , Palmer D. W. , Goss J. P. , Briddon P. R. , Öberg S. 
Published: July 2012

AbstractBesides their importance for quantum information processing, NV defects are crucial agents for the diffusion and aggregation of nitrogen in diamond. In the absence of transition metals, it is thought that the first stage of nitrogen aggregation, where close neighbour nitrogen pairs are formed, is mediated by NV defects. Here we use density functional theory to explore the barriers to NV diffusion. We conclude that the barrier is around 5 eV when there is a ready source of vacancies and that this barrier is weakly dependent on pressure.
Electrically active defects at AlN/Si interface studied by DLTS and ESR
Authors: Simoen Eddy , Visalli Domenica , Van Hove Marleen , Leys Maarten , Favia Paola , Bender Hugo , Borghs Gustaaf , Nguyen Ahn Puc Duc , Stesmans Andre 
Published: July 2012

AbstractA combined deep‐level transient spectroscopy (DLTS) and electron spin resonance (ESR) study is performed to identify the electrically active defects at the AlN/Si (111) interface. It is shown that the density of deep‐level states not only depends on the thermal budget of the epitaxial deposition but also on the strain built up during growth and upon cooling to room temperature (RT). At the same time, diffusion of Si into the 200 nm thick AlN layer produces a thin crystalline Si3N4 interfacial layer, identified by transmission electron microscopy (TEM). This gives rise to so‐called dangling bond Pb centres at the Si3N4/Si (111) interface. In addition, a strong evolution of the electrically active defect clusters in the silicon substrate close to the interface has been observed both in DLTS and ESR.
Ab initio analysis of a vacancy and a self‐interstitial near single crystal silicon surfaces: Implications for intrinsic point defect incorporation during crystal growth from a melt
Authors: Kamiyama Eiji , Sueoka Koji , Vanhellemont Jan 
Published: July 2012

AbstractThe microscopic model of the Si (001) crystal surface was investigated by first principles calculations to clarify the behavior of intrinsic point defects near crystal surfaces. A c(4 × 2) structure model was used to describe the crystal surface in contact with vacuum. The calculations show lower formation energy near the surface and the existence of formation energy differences between the surface and the bulk for both types of intrinsic point defects. The tetrahedral (T)‐site and the dumbbell (DB)‐site, in which a Si atom is captured from the surface and forms a self‐interstitial, are found as stable sites near the third atomic layer. The T‐site has a barrier of 0.48 eV, whereas the DB‐site has no barrier for the interstitial to penetrate into the crystal from the vacuum. Si atoms in a melt can migrate and reach at the third layer during crystal growth when bulk diffusion coefficient is used. Therefore, the melt/solid interface is always a source of intrinsic point defects.
Diffuse light‐scattering properties of nanocracked and porous MoO3 films self‐formed by electrodeposition and thermal annealing
Authors: Ko Yeong Hwan , Raju Ganji Seeta Rama , Kim Sunkook , Yu Jae Su 
Published: July 2012

AbstractWe report the diffuse light‐scattering properties of nanocracked and porous molybdenum trioxide (MoO3) films deposited on indium tin oxide (ITO) coated glass as a transparent conductive oxide (TCO), caused by the enhanced light diffraction due to high surface roughness as well as narrow slit‐like structures. By utilizing the electrodeposition and thermal annealing processes, the hydrous and amorphous molybdenum oxide films were changed into crystallized MoO3 films with self‐formed nanocracks and rough surface. From the theoretical analysis of the light behavior passing through the morphology of MoO3 films, a considerable diffuse light scattering was predicted. In order to optimize the light‐scattering property, the structural and optical characteristics of MoO3 films on ITO/glass at different applied voltages were investigated. For a proper applied voltage of 2 V, widely distributed nanocracks and rough surface were observed, leading to the enhanced diffuse transmittance of 54% at λ ∼ 410 nm. Additionally, the fabricated MoO3 films on ITO/glass exhibited a more hydrophilic surface.
Pressure‐dependent properties of a multifunctional material: Lithium platinum boride (LiPt3B)
Authors: Aydin Sezgin , Simsek Mehmet 
Published: July 2012

AbstractThis paper presents our study on pressure‐dependent structural, mechanical, dynamical, electronic, and optical properties of lithium platinum boride (LiPt3B) by using a first‐principles plane‐wave pseudopotential method. In order to determine pressure‐dependent mechanical properties of the material and to check its mechanical stability, single‐crystal elastic constants are calculated in the pressure range of 0–80 GPa. It is shown that LiPt3B is mechanically stable throughout the pressure range. From the calculated electronic structure, LiPt3B has a metallic character. The hardness of the material is calculated as a function of pressure, and it is observed that PtB bonds play an important role in the hardness. The optical properties of LiPt3B are calculated by including the Drude term. There are significant changes in the degree and the character of electronic and optical properties of LiPt3B at high pressure. Our pressure‐dependent results revealed that LiPt3B is a ductile, hard, and also good reflective material, thus, we can say that it is very promising multifunctional material for a wide range of electronic and electro‐optical technologies.
Effect of metal cations [Li+, Na+, K+, Be2+, Mg2+, and Ca2+] on the structure of 2‐(3′‐hydroxy‐2′‐pyridyl)benzoxazole: A theoretical investigation
Authors: Yi Pinggui , Liu Zhengjun , Wang Zhaoxu , Yu Xianyong , Zhou Jiming , Hou Bo , Li Qingzhong 
Published: July 2012

AbstractDensity functional theory calculations were performed at the B3LYP/6‐311++G(d,p) level to systematically explore the geometrical multiplicity and binding strength for the complexes formed by alkaline and alkaline earth metal cations, viz. Li+, Na+, K+, Be2+, Mg2+, and Ca2+ (Mn+, hereinafter), with 2‐(3′‐hydroxy‐2′‐pyridyl)benzoxazole. A total of 60 initial structures were designed and optimized, of which 51 optimized structures were found, which could be divided into two different types: monodentate complexes and bidentate complexes. In the cation‐heteroatom complex, bidentate binding is generally stronger than monodentate binding, and of which the bidentate binding with five‐membered ring structure has the strongest interaction. Energy decomposition revealed that the total binding energies mainly come from electrostatic interaction for alkaline metal ion complexes and orbital interaction energy for alkaline earth metal ion complex. In addition, the electron localization function analysis show that only the BeO and BeN bond are covalent character, and others are ionic character. © 2012 Wiley Periodicals, Inc.
The role of benzoic acid in proline‐catalyzed asymmetric michael addition: A density functional theory study
Authors: Shi Hongwei , Huang Xiangui , Liu Guixia , Yu Kunqian , Xu Congying , Li Weihua , Zeng Bubing , Tang Yun 
Published: July 2012

AbstractIn asymmetric Michael addition between ketones and nitroolefins catalyzed by L‐proline, we observed that it was benzoic acid or its derivatives rather than other proton acid that could accelerate the reaction greatly, and different benzoic acid derivatives brought different yields. To explain the experimental phenomena, a density functional theory study was performed to elucidate the mechanism of proline‐catalyzed asymmetric Michael addition with benzoic acid. The results of the theoretical calculation at the level of B3LYP/6‐311+G(2df,p)//B3LYP/6‐31G(d) demonstrated that benzoic acid played two major roles in the formation of nitroalkane: assisting proton transfer and activating the nitro group. In the stage of enamine formation from imine, the energy profiles of benzoic acid derivatives were also calculated to investigate the reasons why different benzoic acid derivatives caused different yields. The results demonstrated that the pKa value was the major factor for p‐substituted benzoic acid derivatives to improve the yields, whereas for m/o‐substituted benzoic acid derivatives, both pKa value and electronic and steric effects could significantly increase the yields. The calculated results would be very helpful for understanding the reaction mechanism of Michael addition and provide some insights into the selection of efficient additives for similar experiments. © 2012 Wiley Periodicals, Inc.
LIFE HISTORY DOES MATTER IN ASSESSING POTENTIAL ECOLOGICAL IMPACTS OF THERMAL CHANGES ON AQUATIC MACROINVERTEBRATES
Authors: Rivers‐Moore N. A. , Dallas H. F. , Ross‐Gillespie V. 
Published: July 2012

ABSTRACTThermal alteration is associated with ecological change in freshwater systems. Global climate change is likely to amplify thermal stresses on aquatic systems. We used cumulative daily heat units to examine potential impacts of temperature changes on selected aquatic organisms using scenario analyses. We selected two species of aquatic macroinvertebrates to test our hypotheses of thermal effects on life history pattern, viz. a univoltine stenothermic ephemeropteran species of conservation importance, and a multivoltine dipteran pest species. A combination of spreadsheet probability and logistic regression models was used to model probabilities of hatching and breeding success, plus population sizes and generation numbers per month, under current and projected 2 °C warmer water temperature scenarios. We propose that cold‐adapted Gondwanaland relic species are likely to become increasingly vulnerable and range limited, whereas multivoltine pest species are likely to become more abundant under scenarios of increased water temperatures. We propose management options that include maintaining river connectivity and dam re‐operation as potential mitigation measures. Copyright © 2012 John Wiley & Sons, Ltd.
Classification of samples into two or more ordered populations with application to a cancer trial
Authors: Conde D. , Fernández M.A. , Rueda C. , Salvador B. 
Published: July 2012

In many applications, especially in cancer treatment and diagnosis, investigators are interested in classifying patients into various diagnosis groups on the basis of molecular data such as gene expression or proteomic data. Often, some of the diagnosis groups are known to be related to higher or lower values of some of the predictors. The standard methods of classifying patients into various groups do not take into account the underlying order. This could potentially result in high misclasiffication rates, especially when the number of groups is larger than two.In this article, we develop classification procedures that exploit the underlying order among the mean values of the predictor variables and the diagnostic groups by using ideas from order‐restricted inference. We generalize the existing methodology on discrimination under restrictions and provide empirical evidence to demonstrate that the proposed methodology improves over the existing unrestricted methodology. The proposed methodology is applied to a bladder cancer data set where the researchers are interested in classifying patients into various groups. Copyright © 2012 John Wiley & Sons, Ltd.
The divestiture of acquired subunits: A resource dependence approach
Authors: Xia Jun , Li Sali 
Published: July 2012

AbstractResource dependence theory has been widely applied to explain interindustry acquisitions, but little is known about how external and internal dependence conditions affect the divestiture of formerly acquired subunits. We argue that subunit divestiture may be a strategic response to mutual dependence and subunit power following acquisition. Our results, based on a sample of divested subunits by U.S. public firms, show that mutual dependence and increased subunit power both reduce the hazard of subunit divestiture. However, the negative effect of mutual dependence diminishes to the extent that subunit power increases, suggesting that increased subunit power may shift away from the mutual‐dependence logic. We discuss the implications of these findings to advance the theory of interindustry divestiture. Copyright © 2012 John Wiley & Sons, Ltd.
On the second-order temperature jump coefficient of a dilute gas
Authors: Radtke Gregg A. , Hadjiconstantinou N. G. , Takata S. , Aoki K. 
Published: July 2012

AbstractWe use LVDSMC (low-variance deviational Monte Carlo) simulations to calculate, under linearized conditions, the second-order temperature jump coefficient for a dilute gas whose temperature is governed by the Poisson equation with a constant forcing term, as in the case of homogeneous volumetric heating. Both the hard-sphere gas and the BGK model of the Boltzmann equation, for which slip/jump coefficients are not functions of temperature, are considered. The temperature jump relation and jump coefficient determined here are closely linked to the general jump relations for time-dependent problems that have yet to be systematically treated in the literature; as a result, they are different from those corresponding to the well-known linear and steady case where the temperature is governed by the homogeneous heat conduction (Laplace) equation.
Prevention of soya-induced enteritis in Atlantic salmon (Salmo salar) by bacteria grown on natural gas is dose dependent and related to epithelial MHC II reactivity and CD8α+ intraepithelial lymphocytes
Authors: Romarheim Odd H. , Hetland Dyveke L. , Skrede Anders , Øverland Margareth , Mydland Liv T. , Landsverk Thor 
Published: July 2012

An experiment was carried out to study the preventive effect of bacterial meal (BM) produced from natural gas against plant-induced enteropathy in Atlantic salmon (Salmo salar). Salmon were fed a diet based on fish meal (FM) or seven diets with 200 g/kg solvent-extracted soyabean meal (SBM) to induce enteritis in combination with increasing levels of BM from 0 to 300 g/kg. Salmon fed a SBM-containing diet without BM developed typical SBM-induced enteritis. The enteritis gradually disappeared with increasing inclusion of BM. By morphometry, no significant (P>0·05) differences in the size of stretches stained for proliferating cell nuclear antigen were found with 150 g/kg BM compared with the FM diet. Increasing BM inclusion caused a gradual decline in the number of cluster of differentiation 8 α positive (CD8α+) intraepithelial lymphocytes, and fish fed BM at 200 g/kg or higher revealed no significant difference from the FM diet. Histological sections stained with antibody for MHC class II (MHC II) showed that fish with intestinal inflammation had more MHC II-reactive cells in the lamina propria and submucosa, but less in the epithelium and brush border, compared with fish without inflammation. There were no significant (P>0·05) differences in growth among the diets, but the highest levels of BM slightly reduced protein digestibility and increased the weight of the distal intestine. In conclusion, the prevention of SBM-induced enteritis by BM is dose dependent and related to intestinal levels of MHC II- and CD8α-reactive cells.
Spatio-temporal patterns ofCampylobactercolonization in Danish broilers
Authors: CHOWDHURY S. , THEMUDO G. E. , SANDBERG M. , ERSBØLL A. K. 
Published: July 2012

SUMMARYDespite a number of risk-factor studies in different countries, the epidemiology ofCampylobactercolonization in broilers, particularly spatial dependencies, is still not well understood. A series of analyses (visualization and exploratory) were therefore conducted in order to obtain a better understanding of the spatial and temporal distribution ofCampylobacterin the Danish broiler population. In this study, we observed a non-random temporal occurrence ofCampylobacter, with high prevalence during summer and low during winter. Significant spatio-temporal clusters were identified in the same areas in the summer months from 2007 to 2009. Range of influence between broiler farms were estimated at distances of 9·6 km and 13·5 km in different years. Identification of areas and time with greater risk indicates variable presence of risk factors with space and time. Implementation of safety measures on farms within high-risk clusters during summer could have an impact in reducing prevalence.