bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical local analysis of relevant internal variables for constitutive modelling of granular materials
Authors: Yunus Yuhanis , Vincens Eric , Cambou Bernard 
Published: October 2009

AbstractDEM simulations on spherical materials have been performed to study the behaviour of model granular materials not only under monotonous stress path such as triaxial compression or extension, but also under two‐way cycling loading paths. Three reference states have been considered to characterize the behaviour of the granular material: the characteristic state, transitory state between volumetric contraction and dilation, the state of maximum resistance and the critical state. These states are regarded with respect to void ratio and anisotropy of fabric which are the two internal variables retained for the description of the internal state of the material. The characteristic state and the state at maximum resistance are clearly dependent on both levels of density and anisotropy at the beginning of a loading path. Bilinear models involving the two internal variables were designed for the characteristic state, the maximum dilatancy and the extent of the dilatancy domain for axisymetric loadings. They show that in each case the effect of density and anisotropy are different in compression and extension. The influence of anisotropy and density seems to be of the same order of magnitude. Copyright © 2009 John Wiley & Sons, Ltd.
High conducting multilayer films from poly(acrylic acid) and graphite by layer‐by‐layer self‐assembly
Authors: Tang Qunwei , Li Qinghua , Lin Jianming , Fan Shijun , Hu De , Wu Jihuai 
Published: October 2009

AbstractExfoliated graphite nanoplatelets were modified by hexadecyltrimethylammonium bromide (C16TAB) and were used for the construction of [poly(acrylic acid)/graphite]n [(PAA/G)n] multilayer films using a layer‐by‐layer (LBL) self‐assembly method. The film thickness was monitored using X‐ray diffraction technique; the results showed that the thickness depended on pH of PAA. Under a lower pH value such as 1.5, the average bilayer thickness was 1.5 nm. Once the pH of PAA was increased to 6.5, the bilayer thickness was around 30 nm. The C16TAB modified (PAA/G)n multilayer films showed high thermal stability and electrical conductivity. A percolation phenomenon occurred at bilayer number of 11, and the mechanism was discussed. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Influence of yarn texture on the mechanical properties of textile composite castings
Authors: Zadhoush A. , Sheikhzadeh M. , Elahidust A. , Pirzadeh E. 
Published: October 2009

AbstractIn this research, mechanical properties of textile composite castings used for immobilizing a damaged limb have been studied. For this purpose, a fabric composite was made using a new knitted fabric and textured yarn for the first time. This composite possesses suitable mechanical properties. Mechanical and physical properties such as tensile, bending, and thickness of materials were studied. Results indicate that the use of textured yarns instead of flat yarns increases the amount of resin retainment in fabrics. Furthermore, it decreases tensile modulus and bending modulus of fabrics. Properties of the castings produced were compared with a valid commercial casting. Sample with textured warp and weft, with linear density of 1,500 den of weft, had the best physical and mechanical properties among produced samples. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Dynamic mechanical analysis of oil palm microfibril‐reinforced acrylonitrile butadiene rubber composites
Authors: Joseph Shaji , Sreekumar P.A. , Kenny Jose M. , Puglia Debora , Thomas Sabu , Joseph Kuruvilla 
Published: October 2009

AbstractThe dynamic mechanical properties of microfibers of oil palm‐reinforced acrylonitrile butadiene rubber (NBR) composites were investigated as a function of fiber content, temperature, treatment, and frequency. The storage modulus (E′) was found to increase with weight fraction of microfibrils due to the increased stiffness imparted by the strong adhesion between the polar matrix and the hydrophilic microfibrils. The damping properties were found to decrease with increase in fiber loading. As the fiber content increases, the damping nature of the composite decreases because of the increased stiffness imparted by the natural fibers. By steam explosion method (STEX), microfibrils are separated from fibers. Natural fibers were undergone treatment such as mercerization, benzoylation, and silane treatment. The NBR is modified by the addition of resorcinol‐hexa‐hydrated silica (HRH) bonding agent. Also dicumyl peroxide (DCP) is used as an alternating vulcanizing agent in the system. In the case of composites containing chemically modified fibers, storage modulus were found to increase. Cole–Cole analysis was made to study the phase behavior of the composite samples. Activation energy for the relaxation processes in different composites was calculated. Morphological studies using scanning electron microscopy of tensile fracture surfaces of treated and untreated composites indicated better fiber matrix/adhesion in the case of treated microfibril‐reinforced composites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Synthesis, electrorheology, and creep behaviors of in situ intercalated polyindole/organo‐montmorillonite conducting nanocomposite
Authors: Erol Ozlem , Unal H. Ibrahim , Sari Bekir 
Published: October 2009

AbstractIn this study, first polyindole (PIN) was synthesized using FeCl3 as an oxidizing agent. Then, an organo‐montmorillonite (O‐MMT) was prepared from virgin montmorillonite (MMT) by cetyltrimethylammonium bromide (CTAB) quaternary ammonium salt. Further, PIN/O‐MMT conducting nanocomposite was prepared with 18% O‐MMT content. The samples of PIN, MMT, O‐MMT, and PIN/O‐MMT nanocomposite were characterized by FTIR spectroscopy, thermogravimetric analysis (TGA), X‐ray diffraction (XRD), elemental analysis, conductivity, magnetic susceptibility, density, particle size measurements, and scanning electron microscopy (SEM) method. Characterization results showed a successfully prepared PIN/O‐MMT nanocomposite having both intercalated and exfoliated structures. A series of concentrations (5–25%, m/m) were prepared from those above‐mentioned materials in silicone oil (SO) and their sedimentation stabilities were determined. The suspensions were subjected to an external electric field strength and electrorheological (ER) activity was observed. The effects of dispersed particle concentration, shear rate, external electric field strength, frequency, and temperature onto ER activities of these suspensions were investigated. Creep tests were applied to all the four suspensions and recoverable viscoelastic deformations observed. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Properties of kenaf fiber/polylactic acid biocomposites plasticized with polyethylene glycol
Authors: Taib Razaina Mat , Ramarad Suganti , Ishak Zainal Arifin Mohd , Todo Mitsugu 
Published: October 2009

AbstractBiocomposites of kenaf fiber (KF) and polylactic acid (PLA) were prepared by an internal mixer and compression molding. PLA was plasticized with polyethylene glycol (PEG) (10 wt%) and evaluated as the polymer matrix (p‐PLA). Fiber loadings were varied between 0 and 40 wt%. The tensile, dynamic mechanical, and morphological properties and water absorption behavior of these composites were studied. Reinforcing effect of KF was observed when fiber loading exceeded 10 wt% despite of the inferior fiber‐matrix adhesion observed via scanning electron microscopy (SEM). Un‐plasticized PLA/KF composite exhibited higher tensile properties than its plasticized counterpart. Fiber breakage and heavily coated short pulled‐out of fibers were observed from the SEM micrographs of the composite. The presence of PEG might have disturbed the fiber‐matrix interaction between KF and PLA in the plasticized composites. Addition of PEG slightly improved the un‐notched impact strength of the composites. Dynamic mechanical analysis showed that the storage and loss moduli of p‐PLA/KF composites increased with the increase in fiber loading due to increasing restrictions to mobility of the polymer molecules. The tan delta of the composites in contrast showed an opposite trend. p‐PLA and p‐PLA/KF composites exhibited non‐Fickian behavior of water absorption. SEM examination revealed microcracks on p‐PLA and p‐PLA/KF surfaces. POLYM. COMPOS., 31:1213–1222, 2010. © 2009 Society of Plastics Engineers
Extrusion of polyethylene/polypropylene blends with microfibrillar‐phase morphology
Authors: Polaskova Martina , Cermak Roman , Sedlacek Tomas , Kalus Jakub , Obadal Martin , Saha Petr 
Published: October 2009

AbstractExtrusion of immiscible polymers under special conditions can lead to creation of microfibrillar‐phase morphology, ensuring significant increase of mechanical properties of polymer profiles. Polyethylene/polypropylene blend extrudates with microfibrillar‐phase morphology (polypropylene microfibrils reinforcing polyethylene matrix phase) were prepared through continuous extrusion with semihyperbolic‐converging die enabling elongation and orientation of microfibrils in flow direction. Structure of extruded profiles was examined using electron microscopy and wide‐angle X‐ray scattering. Tensile tests proved that extrudates with microfibrillar‐phase morphology show significantly higher mechanical properties than the conventional extrudates. The presented concept offers possibility of replacing the existing expensive multi‐component medical devices with fully polymeric tools. POLYM. COMPOS., 31:1427–1433, 2010. © 2009 Society of Plastics Engineers
Cytohistological and phytochemical study of madder root extracts obtained by ultrasonic and classical extractions
Authors: Cuoco Guillaume , Mathe Carole , Archier Paul , El Maâtaoui Mohamed , Vieillescazes Cathy 
Published: October 2009

AbstractIntroduction – Madder (Rubia tinctorum) has been used since ancient times as a source of pigments for dyeing and painting. Madder dyes are localised in roots and the native chemical population is composed of glycosiled and aglycone compounds. The aim of this study is to elaborate an efficient extraction process without any chemical denaturation of dyes.Objective – To compare an optimised ultrasonic process, using for madder dye extraction, with two conventional procedures and to determine the efficiency of ultrasound on these vegetable matrix.Methodology – Madder roots were extract in a methanol–water mixture in 37 : 63 (v/v) for ultrasound and 80 : 20 (v/v) for reflux and agitation. HPLC‐PAD analyses showed the anthraquinone proportion for each extraction process and their denaturing effects. Finally, cytohistological observations were made to show the consequence of each process on the cell organisation in madder roots.Results – The results showed that the amount of extracted dyes was higher with UAE than with agitation and reflux. HPLC‐PAD analysis revealed that the anthraquinone composition differed according to the extraction procedure. The UAE extracts presented an important richness in terms of anthraquinonic compounds that suggests a preserving effect. Cytohistological observations showed that the main alterations concerned the cell walls of phloem. After UAE the walls exhibited numerous pitted areas reflecting an ultrasound‐induced cavitation that enhances the extraction effectiveness of this method.Conclusion – The study has shown the improvement of madder roots extraction both quantitatively and qualitatively using the efficiency of ultrasound‐assisted extraction in comparison with magnetic agitation and reflux techniques. Copyright © 2009 John Wiley & Sons, Ltd.
Placental protein 13 as a first trimester screening marker for aneuploidy
Authors: Koster M. P. H. , Wortelboer E. J. , Cuckle H. S. , Stoutenbeek Ph. , Visser G. H. A. , Schielen P. C. J. I. 
Published: October 2009

AbstractObjectiveTo determine whether Placental Protein 13 (PP13) could be an additional marker in first trimester screening for aneuploidies.MethodsTo evaluate differences in multiples of the gestation‐specific normal median (MoMs), PP13 concentrations were measured in serum samples from Down syndrome, trisomy 18 and 13 affected pregnancies and euploid singleton pregnancies (four for each case matched for duration of storage, maternal weight and age).ResultsThe PP13 MoM in Down syndrome cases (n = 153) was 0.91 [not statistically significant from controls (n = 853); P = 0.06; Wilcoxon rank sum test, two‐tail]. PP13 MoMs were decreased in trisomy 18 (n = 38—median MoM 0.64; P < 0.0001) and trisomy 13 cases (n = 23—median MoM 0.46; P < 0.0001). There was a slight upward trend in MoM values of the Down syndrome cases with gestational weeks. The PP13 MoM was significantly correlated with the pregnancy associated plasma protein‐A MoM and the free β‐subunit of human chorion gonadotrophin (fβ‐hCG) MoM.ConclusionPP13 does not seem to be a good marker for Down syndrome. PP13 MoMs are, however, significantly lower in trisomy 18 and 13 pregnancies. The addition of PP13 to the current screening test could be valuable for improving the discrimination of aneuploid from euploid pregnancies. Copyright © 2009 John Wiley & Sons, Ltd.
Recent permafrost degradation in bogs of the James Bay area, northern Quebec, Canada
Authors: Thibault Simon , Payette Serge 
Published: October 2009

AbstractSmall palsas with very thin frozen layers are present within the peat deposits east of James Bay. Most of these permafrost landforms are in an advanced stage of decay within raised bogs between 51°45′N and 55°N. Air photographs, air‐borne surveys and ground‐truthing of permafrost indicate a recent northward recession of the permafrost boundary by about 130 km, most of which likely happened in the past 50 years. Copyright © 2009 John Wiley & Sons, Ltd.
Raman scattering from ferrocene encapsulated in narrow diameter carbon nanotubes
Authors: Plank W. , Kuzmany H. , Pfeiffer R. , Saito T. , Iijima S. 
Published: October 2009

AbstractWe studied peapods prepared with ferrocene (dicyclopentadienyl iron, Fe(Cp)2) as filling species, which makes CNTs with diameters down to 1.1 nm accessible for filling. Two different single‐wall carbon nanotube (SWCNT) samples with mean diameters of 1.1 nm (HiPco) and 1.6 nm (DIPS) were used. Filling was done from the gas phase at elevated temperatures. Sample analysis was done by multifrequency Raman spectroscopy.The Raman response from the encapsulated molecule could be observed through the wall of the CNTs, confirming the encapsulation of the employed molecular species. We observed a sharp decrease of the radial breathing mode intensity for the peapod samples compared to the unfilled CNTs. Ferrocene peapods were transformed to double wall carbon nanotubes (DWCNTs) in a heat induced growth process.
Prediction of HIV‐1 Protease Inhibitors Using Machine Learning Approaches
Authors: Rao Hanbing , Yang Guobing , Tan Ningxin , Li Ping , Li Zerong , Li Xiangyuan 
Published: October 2009

AbstractIn this study, multiple machine learning approaches, including support vector machine (SVM), k‐nearest neighbor (k‐NN), artificial neural networks (ANN) and logistic regression (LR), are applied for classification of HIV‐1 protease inhibitors(PIs) from molecular structure. A diverse set of 641 compounds, including 414 active agents (PIs+) and 227 inactive agents (PIs−), are adopted to develop the classification models. A hybrid feature selection method, which combines Fischer's score and Monte Carlo simulated annealing embedded in the support vector machine approach, is used to select the relevant descriptors from a pool of 1559 molecular descriptors. Three validation methods are employed to validate the model in this study. The first one is the five‐fold cross validation method and the averaged prediction accuracies for these machine learning approaches are between 83.9–93.5% for PIs+and between 67.0–77.7% for PIs−agents. The second validation method is the external test set and the prediction accuracies for PIs+are between 84.6–95.2% and for PIs−agents are between 63.2–87.7%. These two validation methods show that the SVM model has better overall performance than other three machine learning models. The third validation method is the y‐scrambling method, which shows no obvious chance correction in the developed SVM model. The prediction method proposed in this work can give better generalization ability than other recently published methods and can be used as an alternative fast filter in the virtual screening of large chemical database.
Facile synthesis of 4‐mercaptophenylboronic acid functionalized gold nanoparticles for selective enrichment of glycopeptides
Authors: Yao Guoping , Zhang Huaiyuan , Deng Chunhui , Lu Haojie , Zhang Xiangmin , Yang Pengyuan 
Published: October 2009

AbstractIn the work, 4‐mercaptophenylboronic acid (4‐MPBA)‐functionalized gold nanoparticles were synthesized via a facile approach. At first, gold nanoparticles (about 50 nm) were prepared by a simple and convenient hydrothermal method based on a polyol process. Then, gold nanoparticles were modified with 4‐MPBA by the well‐known reaction of Au with the thiol groups. The MPBA‐functionalized gold nanoparticles were characterized by Fourier transform infrared spectra and UV/Vis adsorption spectra. Due to the fact that the boronic acid group on the surface of 4‐MPBA‐modified gold particles can form tight yet reversible covalent bonds with glycopeptides containing cis‐1,2‐diols groups, the MPBA‐modified gold nanoparticles were successfully applied to selective enrichment of glycopeptides. Isolation and enrichment of glycopeptides in a standard protein (asialofetuin and horseradish peroxidase) digestion and a complex sample were performed using MPBA‐modified gold nanoparticles, followed by matrix‐assisted laser desorption/ionization quadruple ion trap time‐of‐flight (MALDI‐QIT‐TOF) mass spectrometric analysis. The experimental results demonstrated that MPBA‐modified gold nanoparticles synthesized by the facile approach have the powerful potential for selective enrichment of glyciopeptides, and can be an alternative tool in glycoproteomics. Copyright © 2009 John Wiley & Sons, Ltd.
Use of liquid chromatography/tandem mass spectrometric molecular fingerprinting for the rapid structural identification of pharmaceutical impurities
Authors: Li Min , Wang Xin , Chen Bin , Lin Mingxiang , Buevich Alexei V. , Chan Tze‐Ming , Rustum Abu M. 
Published: October 2009

AbstractUse of liquid chromatography/tandem mass spectrometric (LC/MSn) molecular fingerprinting is systematically demonstrated as a very effective tool for rapid structural elucidation of pharmaceutical impurities through a case study in which three isomers of betamethasone sodium phosphate (BSP) were rapidly identified as degradants formed due to the D‐homoannular ring expansion of the steroid core structure of BSP in the solid state. The rapid structural elucidation of these degradants was achieved by matching or closely matching the UV profiles, molecular weights, and more importantly the fragmentation patterns obtained from the LC/MSn (n = 1 to 3) analysis of their enzyme‐catalyzed hydrolytic products, respectively, with those of a D‐homoannular isomer of betamethasone available in our LC/MSn molecular fingerprint database. This strategy of using LC/MSn molecular fingerprinting to obtain high‐confidence structures of unknown species is then validated by structure verification through one‐ (1D) and two‐dimensional (2D) nuclear magnetic resonance (NMR) experiments. Copyright © 2009 John Wiley & Sons, Ltd.
Nicotine, acetanilide and urea multi‐level 2H‐, 13C‐ and 15N‐abundance reference materials for continuous‐flow isotope ratio mass spectrometry
Authors: Schimmelmann Arndt , Albertino Andrea , Sauer Peter E. , Qi Haiping , Molinie Roland , Mesnard François 
Published: October 2009

AbstractAccurate determinations of stable isotope ratios require a calibration using at least two reference materials with different isotopic compositions to anchor the isotopic scale and compensate for differences in machine slope. Ideally, the δ values of these reference materials should bracket the isotopic range of samples with unknown δ values. While the practice of analyzing two isotopically distinct reference materials is common for water (VSMOW‐SLAP) and carbonates (NBS 19 and L‐SVEC), the lack of widely available organic reference materials with distinct isotopic composition has hindered the practice when analyzing organic materials by elemental analysis/isotope ratio mass spectrometry (EA‐IRMS). At present only L‐glutamic acids USGS40 and USGS41 satisfy these requirements for δ13C and δ15N, with the limitation that L‐glutamic acid is not suitable for analysis by gas chromatography (GC). We describe the development and quality testing of (i) four nicotine laboratory reference materials for on‐line (i.e. continuous flow) hydrogen reductive gas chromatography‐isotope ratio mass‐spectrometry (GC‐IRMS), (ii) five nicotines for oxidative C, N gas chromatography‐combustion‐isotope ratio mass‐spectrometry (GC‐C‐IRMS, or GC‐IRMS), and (iii) also three acetanilide and three urea reference materials for on‐line oxidative EA‐IRMS for C and N. Isotopic off‐line calibration against international stable isotope measurement standards at Indiana University adhered to the ‘principle of identical treatment’. The new reference materials cover the following isotopic ranges: δ2Hnicotine −162 to −45‰, δ13Cnicotine −30.05 to +7.72‰, δ15Nnicotine −6.03 to +33.62‰; δ15Nacetanilide +1.18 to +40.57‰; δ13Curea −34.13 to +11.71‰, δ15Nurea +0.26 to +40.61‰ (recommended δ values refer to calibration with NBS 19, L‐SVEC, IAEA‐N‐1, and IAEA‐N‐2). Nicotines fill a gap as the first organic nitrogen stable isotope reference materials for GC‐IRMS that are available with different δ15N values. Comparative δ13C and δ15N on‐line EA‐IRMS data from 14 volunteering laboratories document the usefulness and reliability of acetanilides and ureas as EA‐IRMS reference materials. Published in 2009 by John Wiley & Sons, Ltd.
Validation of deuterium and oxygen18 in urine and saliva samples from children using on‐line continuous‐flow isotope ratio mass spectrometry
Authors: Schierbeek H. , Rieken R. , Dorst K. Y. , Penning C. , van Goudoever J. B. 
Published: October 2009

AbstractThe doubly labelled water method is valuable for measuring energy expenditure in humans. It usually involves blood or urine sampling, which might be difficult in neonates and children with cerebral palsy or other disabilities. We therefore aimed to validate a method making use of saliva samples analyzed by automated thermal conversion elemental analyzer in combination with isotope ratio mass spectrometry (TC‐EA/IRMS). The subjects received labelled water orally and urine and saliva samples were collected and analyzed. Deuterium as well as oxygen18 was measured in one single run using a peak jump method. Excellent linearity was found for measurement of enrichments of deuterium (R2 = 0.9999) and oxygen18 (R2 = 0.9999). The intra‐assay precision and the inter‐assay precision of the measurement of two standards were good for both deuterium and oxygen18. The variation between urine and saliva samples was small (4.83% for deuterium and 2.33% for oxygen18 n = 40). Saliva sampling is to be preferred, therefore, as it can be easily collected and is non‐invasive. Moreover, its time of production is almost exactly known. The TC‐EA/IRMS method is a good alternative to the more laborious off‐line IRMS measurements. Copyright © 2009 John Wiley & Sons, Ltd.