bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion Crosslinking Kinetics of Thermoset Polymers
Authors: Patlazhan Stanislav A. , Berlin Alexander A. , Bouquey Michel , Serra Christophe A. , Muller René 
Published: May 2011

AbstractThe problem of the delayed crosslinking arising due to the diffusion of a crosslinker molecule from a vector particle within a thermoset polymer matrix is discussed. The crosslinker molecules, initially embedded in the vector particles, diffuse from the particle to the polymer matrix and react with the functional groups grafted to polymer chains. The two‐step diffusion crosslink kinetics is studied theoretically on the example of polyethylene functionalized with anhydride groups reacting with 1,4‐butanediol as a crosslinker molecule. This provides the independent of time limiting distribution functions of the concentration of crosslinks, unreacted and intermediate functional groups, which are shown to be rather sensitive to system parameters as rates of chemical reactions, ratio of diffusion coefficients of matrix to vector particles, stoichiometric composition of the reactive groups, etc. The nonmonotonic distribution of the crosslink concentration around the vector particles at certain range of the parameters is revealed. magnified image
In Silico Studies of the Relationship Between Chemical Structure and Drug Induced Phospholipidosis
Authors: Przybylak Katarzyna R. , Cronin Mark T. D. 
Published: May 2011

AbstractDrug‐induced phospholipidosis (PLD) is a side effect of the administration of cationic amphiphilic drugs (CADs). It is desirable to identify and screen compounds with the potential to induce PLD as early as possible in drug development. Recently, a number of in silico methods have been developed to predict PLD. These models are low‐cost and high‐throughput strategies; however, they produce a high number of false positive predictions. The aim of this study was to assess the predictive performance of existing in silico approaches and to develop new strategies for the rapid identification of the potential PLD‐inducers. Studies on 450 chemicals confirmed the high false positive rate of prediction of models based only on log P and pKa values. Modification of the methods by incorporating structural information gave moderate improvements in the prediction performance. Therefore, a new strategy, based on molecular fragments captured by SMARTS strings was developed. These structural fragments were able to identify potential PLD‐inducers and achieved a high sensitivity of 85 %. The results showed that the phospholipidosis is linked directly to the molecular structure of chemical; therefore the SMARTS pattern methodology could be used as a first line of screening of PLD potential during the drug discovery process.
Contribution of Non‐Canonical Interactions to the Stability of Sm/LSm Oligomeric Assemblies
Authors: Stojanović Srđan Đ. , Isenović Esma R. , Zarić Božidarka L. 
Published: May 2011

AbstractThe distinguishing property of Sm/LSm protein assemblies is their high stability. In order to better understand the nature of Sm/LSm protein oligomers in this study we have analyzed the contribution of non‐canonical interactions to the stability of assemblies. The predominant types of non‐canonical interactions at Sm/LSm protein interfaces are CH⋅⋅⋅O, and CH⋅⋅⋅N interactions represented at interfaces. Our results show low percentages of XH–π and non‐canonical interactions involving sulfur atoms, while the backbone groups were less frequently involved. The data show a high percentage of non‐canonical interactions in interfaces formed by charged residues with Lys and Arg, these being the major charged donors. The main chain non‐canonical interactions might be slightly more linear than the side chain interactions, and they have somewhat shorter median distances. Comparing the stabilizing amino acid residues with amino acids which build non‐canonical interactions at interfaces shows that certain amino acids like Phe, Pro, His and Tyr are involved with a high percentage. The high conservation score of amino acids that are involved in non‐canonical interactions in protein interfaces is an additional strong argument for their importance in the stabilization of Sm/LSm protein assemblies.
Mechanical properties of chicken feather fibers
Authors: Zhan Mingjiang , Wool Richard P. 
Published: May 2011

AbstractChicken feather fibers (CFFs) are attractive for composite applications. In this study, mechanical properties of the feather barbs were investigated statistically. The strain at break of CFFs had a Gaussian distribution with a mean value of 6.93%. The tensile modulus of CFFs was 3.59 ± 1.09 GPa and average tensile strength was 203 ± 74 MPa, respectively. Both tensile modulus and tensile strength among different feathers were significantly different. The failure of the CFFs followed a Weibull distribution with a scale parameter value of 178.7 MPa and a shape parameter value of 2.32. Overall, the well‐investigated mechanical properties of the CFFs are beneficial for the further study of its applications in composite materials. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Synthesis and characterization of poly(styrene‐co‐butyl acrylate)/clay nanocomposite latexes in miniemulsion by AGET ATRP
Authors: Hatami Leila , Haddadi‐Asl Vahid , Roghani‐Mamaqani Hossein , Ahmadian‐Alam Leila , Salami‐Kalajahi Mehdi 
Published: May 2011

AbstractPolymer/clay nanocomposite latexes in the form of positively charged nanoparticles were synthesized by a newly developed initiating system, activators generated by electron transfer (AGET), which has been employed in atom transfer radical polymerization (ATRP). These clay‐dispersed latexes were synthesized using AGET ATRP of styrene and butyl acrylate in a miniemulsion system in which, ascorbic acid as a reducing agent was added drop wise to reduce termination reactions. Particle size and particle size distribution of resulted nanocomposite latexes were characterized by dynamic light scattering (DLS). These latexes were in the range of 138 to 171 nm in size. Gel permeation chromatography (GPC) was used to characterize the molecular weight and molecular weight distribution of the resultant copolymer nanocomposites. GPC traces showed that polymers of narrow molecular weight distribution and low Polydispersity Index (PDI) have been synthesized; this clearly shows ATRP reaction is conducted successfully. By increasing nanoclay content, molecular weight of the nanocomposites decreases. The presence of the nanofiller increases the thermal stability of the nanocomposites as investigated by thermogravimetric Analysis (TGA). Glass transition temperature of nanocomposites increases compared with the neat copolymer which was studied by differential scanning calorimetry (DSC). scanning electron microscope (SEM) showed sphere morphology of polymer particles synthesized by miniemulsion polymerization. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) results showed that mixed intercalated and exfoliated morphology is obtained. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Behaviors of polyelectrolyte AAm/AMPS/bentonite composite hydrogels in uptake of uranyl ions from aqueous solutions
Authors: Kundakcı Semiha , Üzüm Ömer Barış , Karadağ Erdener 
Published: May 2011

AbstractUranyl ion (UO22+) sorption properties of polyelectrolyte composite hydrogels made by the polymerization of acrylamide (AAm) with 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) and clay such as bentonite (Bent) were investigated as a function of composition to find materials with swelling and uranyl ion sorption properties. Highly swollen AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels were prepared by free radical solution polymerization in aqueous solutions of AAm with AMPS as co‐monomer and two multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4 butanediol dimethacrylate (BDMA). Swelling experiments were performed in water at 25°C, gravimetrically. The influence of AMPS content in hydrogels was examined. Uranyl ion adsorption from aqueous solutions was studied by batch sorption technique at 25°C. The effect of uranyl ion concentration and mass of AMPS on the uranyl ion adsorption were examined. Finally, adsorption capacity (the amount of sorbed uranyl ion per gram of dry hydrogel) (q) was calculated to be 0.67 × 10−3–2.11 × 10−3 mol uranyl ion per gram for the hydrogels. Removal effiency of uranyl ions (RE%) was changed range 9.05–29.92%. The values of partition ratio (Kd) of uranyl ions was calculated to be 0.10–0.43 for AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels, respectively. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
17O NQR and 13C NMR study of hydrogen‐bonded organic ferroelectric croconic acid
Authors: Seliger Janez , Plavec Janez , Šket Primož , Žagar Veselko , Blinc Robert 
Published: May 2011

AbstractThe 1H17O nuclear quadrupole double resonance spectrum and the 13C CP/MAS NMR spectrum of polycrystalline croconic acid, H2C5O5, have been studied at room temperature. Croconic acid has been recently shown to have the highest switchable spontaneous polarization of all organic ferroelectrics and stays polarized up to the decomposition point at around 450 K. Both the 13C NMR and the 17O nuclear quadrupole resonance (NQR) spectra show that there are five crystallorgaphically non‐equivalent carbon and oxygen positions for a given molecule and that therefore the two OH…O bonds are non‐equivalent. From the dipolar structure of the 17O quadrupole resonance spectra the OH distance is determined as being 0.099 ± 0.001 nm in both hydrogen bonds. The large 17O quadrupole coupling constant at the COH as well as at the CO…H oxygen position and the short OH distance demonstrate that the OH…O hydrogen bonds are strongly asymmetric. A correlation of the 17OH…O and OH…17O quadrupole coupling constants versus the O…O distance has been observed in several organic acids. The data for croconic acid significantly deviate from this correlation, what may be the result of the strong long range ferroelectric ordering which influences the electron distribution in the hydrogen bonds.
Seven useful designs
Authors: Julious Steven A. 
Published: May 2011

AbstractWhen designing a clinical trial there is a need to design a study that achieves the objectives of a trial both efficiently and with minimum resources. This paper describes seven trial designs that could possibly be used in clinical development and highlights how a design although not optimal for an individual study may be optimal for a wider clinical program. Copyright © 2011 John Wiley & Sons, Ltd.
Properties and morphology of poly(vinyl alcohol) blends with sago pith bio‐filler as biodegradable composites
Authors: Yee Toh Wen , Rahman W.A.W.A. , Sin Lee Tin 
Published: May 2011

AbstractThe effects of sago pith as a bio‐filler (SPB) on the mechanical and thermal properties of poly(vinyl alcohol) (PVA) were studied. The SPB was obtained from sago pith waste after starch extraction from sago palm. Sago pith waste was dried and ground to produce SPB. The SPB was blended with PVA in a twin‐screw co‐rotating extruder in order to produce PVA‐SPB composites for mechanical, morphology, and thermal analyses. Blending of SPB and PVA improved the tensile modulus, whereas the tensile strength was reduced. This result occurred because SPB increased the rigidity of PVA. However, lack of interfacial adhesion between PVA and SPB caused the loss of reinforcing effects. The morphology analysis showed that a high loading of SPB (>70 wt%) tended to form clusters, as implied by the presence of elongated cavities due to droplet coalescence restricting chain mobility. Besides that, the enthalpy of melting (ΔHm) for 50 wt% of SPB was higher than that of PVA. This observation means that the molecular interaction forces between PVA and SPB were so great as to overtake those of the PVA itself. Thus it was concluded that 40–50 wt% of SPB was preferably blended with PVA to form a biodegradable composite in order to reduce the overall materials cost, rather than to act as a strong reinforcing filler. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers
Synthesis and Characterization of Bis(triaminoguanidinium) 5,5′‐Dinitrimino‐3,3′‐azo‐1H‐1,2,4‐triazolate – A Novel Insensitive Energetic Material
Authors: Dippold Alexander , Klapötke Thomas M. , Martin Franz A. 
Published: May 2011

AbstractThe synthesis of 5,5′‐diamino‐3,3′‐azo‐1H‐1,2,4‐triazole (3) by reaction of 5‐acetylamino‐3‐amino‐1H‐1,2,4‐triazole (2) with potassium permanganate is described. The application of the very straightforward and efficient acetyl protection of 3,5‐diamino‐1H‐1,2,4‐triazole allows selective reactions of the remaining free amino group to form the azo‐functionality. Compound 3 is used as starting material for the synthesis of 5,5′‐dinitrimino‐3,3′‐azo‐1H‐1,2,4‐triazole (4), which subsequently reacted with organic bases (ammonia, hydrazine, guanidine, aminoguanidine, triaminoguanidine) to form the corresponding nitrogen‐rich triazolate salts (5–9). All substances were fully characterized by IR and Raman as well as multinuclear NMR spectroscopy, mass spectrometry, and differential scanning calorimetry. Selected compounds were additionally characterized by low temperature single‐crystal X‐ray diffraction measurements. The heats of formation of 4–9 were calculated by the CBS‐4M method to be 647.7 (4), 401.2 (5), 700.4 (6), 398.4 (7), 676.5 (8), and 1089.2 (9) kJ·mol–1. With these values as well as the experimentally determined densities several detonation parameters were calculated using both computer codes EXPLO5.03 and EXPLO5.04. In addition, the sensitivities of 5–9 were determined by the BAM drophammer and friction tester as well as a small scale electrical discharge device.
Synthesis and Crystal Structure of a Rare Tetra‐Yttrium‐Supported Krebs‐Type Tungstoantimonate
Authors: Tan Rongxin , Pang Xiaohong , Ren Yulan , Wang Xiaohong , Li Rui 
Published: May 2011

AbstractA rare tetra‐yttrium‐supported Krebs‐type tungstoantimonate was prepared in an acidic solution at pH 2.2 and characterized by elemental analysis and IR spectroscopy. Single‐crystal X‐ray analysis was carried out on Na2[{Y(H2O)7}4Sb2W22O76]·14H2O (1), which comprises a Krebs‐type [Sb2W22O76]14– unit supported by four yttrium ions.
Magnetic Ordering and Spin Dynamics of Ba1–xEuxSi Phases
Authors: Spahr Michael , Nesper Reinhard , Ensling Jürgen , Gütlich Philipp , Schenck Alexander , Pinkpank Markus , Chatterji Tapan , Ouladdiaf Bachir 
Published: May 2011

AbstractWe have investigated the magnetic ordering and spin dynamics of the solid solution series Ba1–xEuxSi with 0 < x ≤ 1 applying X‐ray diffraction, electric conductivity measurements, Mössbauer spectroscopy, muon spin depolarization, and neutron diffraction. Our results suggest a spin glass‐like behavior of Ba1–xEuxSi for concentrations close to x = 0.3 exist. Different spin ordering phenomena are found, which are dependent on the relative europium concentrations.
The importance of allochthonous litter input on the biomass of an alien crayfish in farm ponds
Authors: Kobayashi Raita , Maezono Yasunori , Miyashita Tadashi 
Published: May 2011

AbstractTo evaluate the effects of allochthonous litter input on the population density of invasive red swamp crayfish (Procambarus clarkii) in Japanese farm ponds, we analyzed gut contents, stable isotope ratios, and the correlation between crayfish biomass and environmental factors in the ponds. For our correlation analysis, we used Akaike's information criterion (AIC) corrected for small sample size (AICC) to select appropriate models within the generalized linear model. Allochthonous litter input was the most influential variable affecting crayfish biomass, followed by pond area. Gut content analysis demonstrated a positive correlation between the percentage of litter in the crayfish gut and the amount of litter input into the pond from which animals were collected. Crayfish δ13C became increasingly similar to litter δ13C as litter input into ponds increased. Nitrogen isotope signature analysis suggested that microorganisms attached to litter may contribute to crayfish diet. The above results obtained by three complementary approaches demonstrated an important influence of allochthonous litter input on crayfish biomass in farm ponds. We propose that the appropriate management of surrounding forests may be effective in controlling the abundance of exotic crayfish with minimized impacts on native communities.
The Impact of the AIDS Pandemic on Health Services in Africa: Evidence from Demographic and Health Surveys
Authors: Case Anne , Paxson Christina 
Published: May 2011

Abstract
We document the impact of the AIDS crisis on non-AIDS-related health services in 14 sub-Saharan African countries. Using multiple waves of Demographic and Health Surveys (DHS) for each country, we examine antenatal care, birth deliveries, and rates of immunization for children born between 1988 and 2005. We find deterioration in nearly all these dimensions of health care over this period. The most recent DHS survey for each country collected data on HIV prevalence, which allows us to examine the association between HIV burden and health care. We find that erosion of health services is the largest in regions that have developed the highest rates of HIV. Regions of countries that have light AIDS burdens have witnessed small or no declines in health care, using the measures noted above, while those regions shouldering the heaviest burdens have seen the largest erosion in non-HIV-related health services for pregnant women and children. Using semiparametric techniques, we can date the beginning of the divergence in the use of antenatal care and in children’s immunizations between high- and low-HIV regions to the mid-1990s.
Self-Similar Interfacial Crack Growth in Anisotropic Material Under Anti-Plane Shear
Authors: Wu Kuang-Chong 
Published: May 2011

ABSTRACTDynamic propagation of a crack along the interface in an anisotropic material subjected to remote uniform anti-plane shear is studied. The crack is assumed to nucleate from an infinitesimal microcrack and expands with a constant velocity. Explicit expressions for the stress intensity factor and the energy release rate are derived.
An Innovative Phase Shifting System for Non-Destructive Testing
Authors: Chen C. W. , Chang H. Y. , Lee C. K. 
Published: May 2011

ABSTRACTPhase shifting technique is one of the most important technologies in the metrology field. Simply by performing an interferogram measurement, and then adopting the phase shifting technique to unwrap the interferogram into a phase map, tasks such as object surface profile reconstruction, holographic interferometry, electronic speckle pattern interferometry, etc., can all be easily accomplished. An innovative phase shifting system, which uses piezoelectric actuators to execute phase shifting first and then implementing a cellular automata algorithm to unwrap phase data, was designed, built, and tested. Since cellular automata is a true parallel process, and noise appearing within the interferogram will not get propagated, this novel system is far more robust than the systems based on the traditional path following phase-unwrapping algorithm. In addition, this new algorithm also provides us with a way to adopt phase-masks within the cellular automata implementations of the phase unwrap operations. All these newly developed techniques make this newly developed system adaptable to many metrology applications, even when high noise is present or when lateral shear exists within the image field. The successful incorporation of the phase-mask approach into the cellular automata phase unwrapping algorithm essentially makes this newly developed system adaptable to take phase map measurements in many practical applications.
Active Structural Acoustic Control for Rectangular Plate with a Line Moment Excitation
Authors: Lee Jen-Chieh , Chen Jish-Chson 
Published: May 2011

AbstractActive control of noise radiation from vibrating plate excited by a harmonic line moment is analytically investigated. This study model of simple supported rectangular plate with a line moment excitation is used to simulate the vibration of ship hull or fuselage from the flutter of ship deck or aircraft wing respectively. The control is achieved by various configurations of piezoelectric actuators. The strategy of radiated power minimization is used to obtain the optimal control input unit voltage. The numerical results show that the significant attenuation of noise radiated power for volumetric modes in the low frequency range can be achieved with one control actuator located at the center of plate, irrespective of whether the excitation is on or off resonance. The efficiency of the active control is dependent on the location of the line moment and the actuators. It is also shown that the modal suppression and modal restructuring are two physical mechanisms of radiated power attenuation.
The Effect of Motion Curves on the Curvatures of VPLS Transmission Mechanisms with Ruled- and Involute-Revolution Surface Meshing Elements
Authors: Kang Yaw-Hong , Yan Hong-Sen 
Published: May 2011

AbstractThe purpose of this research is to study the effect of motion curves on the curvature of variable pitch lead screw (hereinafter VPLS) transmission mechanisms with different meshing elements. The surfaces of VPLS are generated based on various meshing elements with different specified motion curves. There are three kinds of ruled- and one involute-revolution surface meshing elements, and four types of motion curves are studied, which including modified trapezoidal (MT) curve, modified sine (MS) curve, modified constant velocity (MCV) curve, and polynomial (PL) curve. The curvature analyses include the determination of direction of contact line, induced principal radii of curvature, and lubrication angles between the surfaces of VPLS and various meshing elements. The results of this work provide a comparison between the effect of motion curve on the curvature of VPLS transmission mechanisms with different meshing elements.
Theory of Multilayered Anisotropic Shells Based on an Asymptotic Variational Formulation
Authors: Tarn Jiann-Quo , Wang Yung-Ming , Chang Shi-Horng 
Published: May 2011

ABSTRACTA general theory for multilayered anisotropic elastic shells is developed in an asymptotic variational framework of 3-D elasticity. The generic shell continuum considered is heterogeneous through the thickness. It is shown that the classical laminated shell theory based on Love's assumption arises naturally as the first-order approximation to the 3-D theory. Higher-order corrections can be determined by solving the 2-D shell equations hierarchically. The associated edge conditions at each level of approximation are derived. Various types of shells such as shells of revolution, conical shells, spherical shells, circular cylindrical shells can be treated within the context.
Numerical Simulation and Stability Analysis of Laminar Wake Behind a Circular Cylinder
Authors: Huang Mei-Jiau 
Published: May 2011

ABSTRACTThe transition of a viscous incompressible laminar flow behind a circular cylinder from a steady state to its wake, counterpart at a Reynolds number Re = 100, based on the free stream velocity (U) and the cylinder diameter (D), is directly simulated. The two-dimensional unsteady Navier-Stokes equations are solved numerically by taking advantage of the splitting technique and the spectral element method. The main goal of this work is to explore the frequency-selection mechanism of the wake through the use of the absolute/convective instability theory, which in turn is performed by investigating the one-dimensional Orr-Sommerfeld equation. It is found that the predicted onset frequency based on the maximum-growth criterion is in a good agreement with the numerically observed one, although the measured growth rate is found smaller. The saturated frequencies predicted by the maximum-growth criterion and Kock's transition criterion are the same and also close to the measured one. More simulation or experimental data are needed for a further conclusion however.