bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical properties of polyamide 6 reinforced microfibrilar composites
Authors: Dencheva Nadya V. , Oliveira Maria J. , Pouzada Antonio S. , Kearns Mark P. , Denchev Zlatan Z. 
Published: February 2011

AbstractThe mechanical behavior of microfibrilar composites (MFC), consisting of a matrix of high‐density polyethylene (HDPE) and reinforcement of polyamide 6 (PA6) fibrils, with and without compatibilization, was studied. The composites were produced by conventional processing techniques with various shape and arrangement of the PA6 reinforcing entities: long, unidirectional, or crossed bundles of fibrils (UDP and CPC, respectively), middle‐length, randomly oriented bristles (MRB), or non‐oriented micrometric PA6 spheres (NOM). The tensile, flexural, and impact properties of the MFC materials (UDP, CPC, and MRB) were determined as a function of the PA6 reinforcement shape, alignment and content, and compared with those of NOM, the non‐fibrous composite. It was concluded that the in‐situ MFC materials based on HDPE/PA6 blends display improvements in the mechanical behavior when compared with the neat HDPE matrix, e.g., up to 33% for the Young modulus, up to 119% for the ultimate tensile strength, and up to 80% for the flexural stiffness. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Effect of filler‐polymer interactions on the crystalline morphology of PEO‐based solid polymer electrolytes by Y2O3 nano‐fillers
Authors: Liang Guijie , Xu Jie , Xu Weilin , Shen Xiaolin , Zhang Hui , Yao Mu 
Published: February 2011

AbstractA novel lithium solid polymer electrolyte (SPE) based on polyethylene oxide (PEO) matrix and yttrium oxide (Y2O3) as nano‐filler was prepared by solution casting technique. The Lewis acid‐based filler‐polymer coordination interactions between the surface of Y2O3 and the ether oxygen of PEO were proved by FTIR, which induced an obvious modification of crystalline morphology of the PEO‐based SPEs. Polarized optical microscope (POM) analysis shows that the induced nucleation and steric hindrance effects of Y2O3 nano‐filler result in the increased amount as well as decreased size of spherulites in the PEO matrix, respectively. Atomic force microscope (AFM) images indicate the surface morphology of PEO gets rougher as Y2O3 content increases. X‐ray diffractomer (XRD) and differential scanning calorimetry (DSC) results demonstrate the crystallinity of SPEs decreases from 51.1% to 32.5% with the Y2O3 weight ratio [m(Y2O3)/m(PEO+LiI)] increasing from 0 to 0.15. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Poly(butylene succinate)‐based biocomposites filled with polysaccharide nanocrystals: Structure and properties
Authors: Lin Ning , Yu Jiahui , Chang Peter R. , Li Junli , Huang Jin 
Published: February 2011

AbstractIn this work, two polysaccharide nanocrystals‐rod‐like cellulose whisker (CW) and platelet‐like starch nanocrystal (SN) were individually incorporated into an aliphatic thermoplastic polyester to produce biodegradable poly(butylene succinate) (PBS)/nanocrystals biocomposites. At loading levels of 2 wt% CW or 5 wt% SN the PBS‐based nanocomposites showed simultaneous enhancement of strength and elongation compared to the neat PBS. This was primarily attributed to the uniform dispersion of nanofillers and strong interfacial adhesion between filler and matrix. Nucleation of the nanocrystals, formation of a percolating network, and interaction between filler and matrix collectively contributed to the improvement of crystallinity and thermal properties of the composites. This high performance, fully biodegradable, eco‐friendly nanocomposite will expand the utilization of polysaccharide nanocrystals from renewable bioresources and the practical application of PBS. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
High molecular weight poly (L‐lactic acid) clay nanocomposites via solid‐state polymerization
Authors: Katiyar Vimal , Nanavati Hemant 
Published: February 2011

AbstractWe propose here, a novel technique to synthesize high molecular weight (MW) poly (L‐lactic acid)‐clay nanocomposite (PLACN), via solid state polymerization (SSP). We synthesize prepolymer of PLACN (pre‐PLACN) from both,L‐lactic acid andL‐lactide, as starting materials. Synthesis of pre‐PLACN fromL‐lactic acid is carried out viain situmelt polycondensation (MP) ofL‐lactic acid oligomer, followed by SSP, to achieve high MW PLACN (Mw∼ 138,000 Da). In case ofL‐lactide as the starting material, we prepareL‐lactide–clay intercalated mixture which yields moderate MW pre‐PLACN during subsequent ring opening polymerization (ROP). Interestingly, ROP is performed by using hydroxyl functionalized ternary catalyst system (L‐lactide–Sn(II) octoate–oligo (L‐lactic acid) complex), which provides the terminal hydroxyl end‐groups, required for step‐growth SSP. Pre‐PLACN MW is now increased toMw∼ 127,000 Da, by the subsequent SSP process.1H NMR analyses confirm that these end‐groups, are indeed consumed during SSP. During SSP, the PLACN also achieves up to 90% crystallinity, which may be due to the synchronization of the slow step‐growth SSP of poly(L‐lactic acid) (PLA) with the crystallization kinetics. Optical purity of PLACNs is similar to that of neat PLA, whereas the thermal stability of PLACNs is significantly superior. As evidenced by wide‐angle X‐ray scattering/small‐angle X‐ray scattering analyses and in line with the literature, both, intercalated and exfoliated PLACN morphologies, have been synthesized, by suitable selection of clays. We also verify the correlation between the PLA semicrystalline morphology and the PLACN morphology, which is consistent with those of PLACN synthesized by other techniques. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Curing kinetics of NBR filled with coconut flour
Authors: Herrera R. , Ichazo M.N. , Albano C. , Hernández M. , González J. 
Published: February 2011

AbstractThe purpose of this investigation was to evaluate the effect of the incorporation of 20 phr of coconut woodflour of different particle sizes on the vulcanization kinetics of Nitrile Rubber (NBR) by means of rheometry and differential scanning calorimetry. The vulcanization kinetics results suggest that there might exist agglomerates of small particles (< 300 μm), which interfere with the curing reaction of the NBR. The reaction orders corresponding to the autocatalytic reaction show an increase with the extent of the reaction and with the rise on temperature. A good correlation of the vulcanization kinetics was obtained employing the generic model that involves constants associated to the reaction mechanisms, which in turn depend on the components present in the initial mix and on the autocatalytic reaction. The Osawa and Kissinger equations reproduce in a similar way the vulcanization kinetics of the compounds. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Dielectric, FTIR spectroscopic and atomic force microscopic studies on polypyrrole‐poly(acrylonitrile‐co‐vinyl acetate) composites
Authors: Cetiner Suat , Kalaoglu Fatma , Karakas Hale , Sarac A. Sezai 
Published: February 2011

AbstractIn this study, Poly(acrylonitrile‐co‐vinyl acetate) [P(AN‐co‐VAc)] composite films were fabricated by chemical polymerization of pyrrole (Py) with cerium(IV) (Ce(IV)) on P(AN‐co‐VAc) matrix. The effect of amount of Py and temperature on the composite film properties was studied in a frequency range starting from 0.05 Hz to 10 MHz and in a temperature range from 0 to 250°C. The electric modulus provides a good description of the dielectric relaxation of the conducting polymer composites. The atomic force microscopy images of the polypyrrole (PPy)‐P(AN‐co‐VAc) composites show the polymerization of Py on P(AN‐co‐VAc) matrix producing different sized grainy orientations resulting in higher conductivity values that increase with average grain size. The real [(ε′) or ε′(ω)] and imaginary [(ε″) or ε″(ω)] parts of the permittivity of PPy‐P(AN‐co‐VAc) composite were comparatively higher than PPy‐Polyacrylonitrile (PAN) and P(AN‐co‐VAc). It was also seen that the conductivity of PPy‐P(AN‐co‐VAc) composite was considerably higher than PPy‐PAN and P(AN‐co‐VAc) itself. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Mechanical properties of nanosilica/polypropylene composites under dynamic compression loading
Authors: Omar Mohd Firdaus , Akil Hazizan Md , Ahmad Zainal Arifin 
Published: February 2011

AbstractThis article presents results on the dynamic mechanical properties of PP‐SiO2 nanocomposites, with nanosilica contents of 1, 3, and 5% by weight, at various strain rates using a Split Hopkinson Pressure Bar (SHPB) apparatus. The specimens were prepared using a hot compression technique. The dynamic mechanical characteristics, of PP‐SiO2 nanocomposites, are illustrated in terms of stress–strain curves, up to nearly 1100 s−1 of strain rates. From the results, the yield stress, compression modulus, and compressive strength of the composites, were significantly influenced by the strain rates and nanosilica contents. The values of strain rate sensitivity, and dissipation energy of the composites at various strain rates, were also determined. It was found that the strain rate sensitivity, and the dissipation energy, increased with increasing strain rates. In addition, it was observed that the composites experienced more severe damage under a high strain rate loading, compared to a low strain rate loading. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Umbilical cord insertion into the lower segment of the uterus at 11 to 13 weeks' gestation is associated with maternal serum PAPP‐A
Authors: Hasegawa Junichi , Farina Antonio , Simonazzi Giuliana , Bisulli Maria , Puccetti Chiara , Pilu Gianluigi , Gabrielli Sandro , Rizzo Nicola 
Published: February 2011

AbstractObjectivesTo evaluate whether the location of the placental cord insertion (CI) at 11 to 13 weeks' gestation affects the maternal serum pregnancy‐associated plasma protein‐A (PAPP‐A).MethodsCohort study was conducted in patients who underwent the first trimester screening including nuchal translucency and blood test. We additionally documented the CI site. The thickness of the placenta under the CI and the minimum distance on the uterine wall between the internal cervical os and the CI (Dis) were measured. The subjects were divided into two groups. Below the tenth percentile in multiples of median (MoM) of Dis were defined as cases in which CI was located on the lower uterine segment (low CI) and the others were defined as controls.ResultsA total of 117 subjects were analyzed. The thickness of the placenta (r = 0.237, p = 0.010) and Dis (r = 0.243, p = 0.008) was correlated with the crown‐rump length (CRL). The maternal serum PAPP‐A MoM in the low CI group was lower than in controls (0.76 ± 0.34 vs 1.16 ± 0.55; p = 0.009), whereas the other ultrasonographic measurements and maternal demographics were not different between the two groups.ConclusionCI on the lower segment of the uterus is associated with low maternal serum PAPP‐A MoM levels. Copyright © 2011 John Wiley & Sons, Ltd.
Novel materials based on chitosan and cellulose
Authors: Fernandes Susana CM , Freire Carmen SR , Silvestre Armando JD , Pascoal Neto Carlos , Gandini Alessandro 
Published: February 2011

AbstractThis review provides a brief overview of the recent research efforts carried out at the CICECO laboratory of the University of Aveiro on novel materials based on chitosan within the background of previous investigations of similar counterparts. Most of this work is devoted to different modes of combining chitosans of various molecular weights and degrees of deacetylation (including appropriately modified chitosans providing either fluorescent properties or water solubility) with cellulose fibres of various sizes (standard to nanosize), morphologies (conventional papers, nanofibrillated or bacterial strands) and assemblies (composites or paper coating and impregnation). Additionally, the radical transformation of chitin and chitosan low‐quality residues into viscous polyols by a straightforward oxypropylation is also discussed. The results of these investigations show the remarkable potential of chitosan as a source of promising blends and composites, among other novel materials. Copyright © 2011 Society of Chemical Industry
Preparation of pH‐sensitive star‐shaped aliphatic polyesters as precursors of polymersomes
Authors: Riva Raphaël , Lazzari Wenda , Billiet Leen , Du Prez Filip , Jérôme Christine , Lecomte Philippe 
Published: February 2011

AbstractThis article reports on the synthesis of a new pH‐sensitive amphiphilic A2B mikto‐arm star‐shaped aliphatic copolyester [with A = poly(ε‐caprolactone) and B = tertiary amine‐bearing poly(ε‐caprolactone)] with two hydrophobic arms and one hydrophilic arm when protonated at pH = 5.5. First, the ring‐opening polymerization of ε‐caprolactone (εCL) was initiated by an aliphatic diol substituted by an alkyne. The copper(I) catalyzed azide‐alkyne cycloaddition (CuAAC) was use to convert the alkyne into a hydroxyl group prone to initiate the ring‐opening copolymerization of γ‐bromo‐ε‐caprolactone (γBrεCL) and εCL. After the substitution of the bromide atoms into azide functions, the N,N‐dimethylprop‐2‐yn‐1‐amine was grafted onto the azide bearing PCL arm by CuAAC, with the purpose to make the B arm hydrophilic at low pH. The precursors of the A2B copolymers were characterized by 1H NMR, SEC, and MALDI‐TOF. As expected, the A2B copolyester was soluble into water at pH = 5. The formation of polymersomes in water at pH 5 was assessed by DLS and TEM analyses. The effects of the architecture and the molecular weight of the A2B copolymers on the formation of polymersomes were investigated. Moreover, the versatility of our approach was demonstrated by the synthesis of an AB2 star‐shaped copolyester. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
An efficient way to functionalize graphene sheets with presynthesized polymer via ATNRC chemistry
Authors: Deng Yan , Li Yongjun , Dai Jing , Lang Meidong , Huang Xiaoyu 
Published: February 2011

AbstractGraphene nanosheets offer intriguing electronic, thermal and mechanical properties and are expected to find a variety of applications in high‐performance nanocomposite materials. The great challenge of exfoliating and dispersing pristine graphite or graphene sheets in various solvents or matrices can be achieved by facilely and properly chemical functionalization of the carbon nanosheets. Here we reported an efficient way to functionalize graphene sheets with presynthesized polymer via a combination of atom transfer nitroxide radical coupling chemistry with the grafting‐onto strategy, which enable us to functionalize graphene sheets with well‐defined polymer synthesized via living radical polymerization. A radical scavenger species, 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO), was firstly anchored onto COOH groups on graphene oxide (GO) to afford TEMPO‐functionalized graphene sheets (GS‐TEMPO), meanwhile, the GO sheets were thermally reduced. Next, GS‐TEMPO reacted with Br‐terminated well‐defined poly(N‐isopropylacrylamide) (PNIPAM) homopolymer, which was presynthesized by SET‐LRP, in the presence of CuBr/N,N,N′,N′,N″‐pentamethyldiethylenetriamine to form PNIPAM‐graphene sheets (GS‐PNIPAM) nanocomposite in which the polymers were covalently linked onto the graphene via the alkoxyamine conjunction points. The PNIPAM‐modified graphene sheets are easily dispersible in organic solvents and water, and a temperature‐induced phase transition was founded in the water suspension of GS‐PNIPAM. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Manipulation of Lipase Activity by the Helium Radio‐Frequency, Atmospheric‐Pressure Glow Discharge Plasma Jet
Authors: Li He‐Ping , Wang Li‐Yan , Li Guo , Jin Li‐Hua , Le Pei‐Si , Zhao Hong‐Xin , Xing Xin‐Hui , Bao Cheng‐Yu 
Published: February 2011

AbstractThe sub‐lethal effects of the radio‐frequency, atmospheric‐pressure glow discharge plasma jet on the lipase are studied. The experimental measurements show that the activity of the lipase increases significantly after treated by the plasma jet within one minute. This enhancing effect is attributed to the changes of the structures of the lipase. The chemically reactive species in the plasma jet region play a major role to the alterations of the lipase secondary and tertiary structures, compared with heat, UV radiation, charged particles, intensified electric field and/or ozone. magnified image
Crystal structure of a soluble form of human monoglyceride lipase in complex with an inhibitor at 1.35 Å resolution
Authors: Schalk‐Hihi Céline , Schubert Carsten , Alexander Richard , Bayoumy Shariff , Clemente Jose C. , Deckman Ingrid , DesJarlais Renee L. , Dzordzorme Keli C. , Flores Christopher M. , Grasberger Bruce , Kranz James K. , Lewandowski Frank , Liu Li , Ma Hongchang , Maguire Diane , Macielag Mark J. , McDonnell Mark E. , Mezzasalma Haarlander Tara , Miller Robyn , Milligan Cindy , Reynolds Charles , Kuo Lawrence C. 
Published: February 2011

AbstractA high‐resolution structure of a ligand‐bound, soluble form of human monoglyceride lipase (MGL) is presented. The structure highlights a novel conformation of the regulatory lid‐domain present in the lipase family as well as the binding mode of a pharmaceutically relevant reversible inhibitor. Analysis of the structure lacking the inhibitor indicates that the closed conformation can accommodate the native substrate 2‐arachidonoyl glycerol. A model is proposed in which MGL undergoes conformational and electrostatic changes during the catalytic cycle ultimately resulting in its dissociation from the membrane upon completion of the cycle. In addition, the study outlines a successful approach to transform membrane associated proteins, which tend to aggregate upon purification, into a monomeric and soluble form.
Understanding the binding mode and function of BMS‐488043 against HIV‐1 viral entry
Authors: Da Lin‐Tai , Quan Jun‐Min , Wu Yun‐Dong 
Published: February 2011

AbstractA recently discovered small‐molecule inhibitor, BMS‐488043 (BMS‐488), for the invasion of Human immunodeficiency virus Type 1 (HIV‐1), shows a high activity against the entry of diversified HIV‐1. Docking and molecular dynamic studies have been carried out to understand the binding mode of BMS‐488 to gp120 as well as the effect of the small molecule on the conformational change of gp120 induced by CD4 binding. The results indicate that BMS‐488 can accommodate in the CD4 binding pocket and interfere the CD4 binding in a noncompetitive mode. The piperazine group of BMS‐488 prevents the bridging sheet formation of gp120 induced by the CD4 binding mainly through blocking the rotation of the Trp112 located on the α1 helix of gp120. The bridging sheet formation cannot be blocked for the W112A mutant of gp120 due to the reduced steric hindrance, in agreement with its significant resistance to the BMS inhibitor. The aza‐indole ring is likely to interfere the exposure of gp41 by stacking within the β3‐β5 and LB loops to disrupt the close packing of Pro212‐His66‐Phe210. The mode of action of BMS‐488 also accommodates many mutagenesis results related to BMS‐488 activity. Proteins 2011; © 2011 Wiley‐Liss, Inc.
Structure of an archaeal‐type phosphoenolpyruvate carboxylase sensitive to inhibition by aspartate
Authors: Dharmarajan Lakshmi , Kraszewski Jessica L. , Mukhopadhyay Biswarup , Dunten Pete W. 
Published: February 2011

AbstractThe crystal structure of an archaeal‐type phosphoenolpyruvate carboxylase from Clostridium perfringens has been determined based on X‐ray data extending to 3 Å. The asymmetric unit of the structure includes two tetramers (each a dimer‐of‐dimers) of the enzyme. The precipitant, malonate, employed for the crystallization is itself a weak inhibitor of phosphoenolpyruvate carboxylase and a malonate molecule is seen in the active‐site in the crystal structure. The allosteric binding sites for aspartate (an inhibitor) and glucose‐6‐phosphate (an activator) observed in the Escherichia coli and Zea mays phosphoenolpyruvate carboxylase structures, respectively, are not conserved in the C. perfringens structure. Aspartate inhibits the C. perfringens enzyme competitively with respect to the substrate, Mg++. phosphoenolpyruvate. A mechanism for inhibition is proposed based on the structure and sequence comparisons with other archaeal‐type phosphoenolpyruvate carboxylases with differing sensitivity to inhibition by aspartate. Proteins 2011; © 2011 Wiley‐Liss, Inc.
Objective analysis of process safety audit data with microsoft access
Authors: Forest Jerry J. 
Published: February 2011

AbstractIn developing systems for process safety, compliance audits provide essential verification that practices and procedures are developed and are effective for compliance. Data collected during compliance audits is often subjective and findings are descriptive in nature. Therefore, it is difficult to complete objective analysis of audit data across standards/procedures to surface systemic management system gaps and to compare site performance across a company. Complete analysis of process safety audit data is analogous to incident investigation causal factor assignment, data analysis, and cause elimination.This article describes a database solution that:
Provides a data collection method for compliance audits that allows for easy database input, thereby reducing overall data handling.
Structures process safety procedures by management system element so that these elements can be examined across various procedures.
Groups compliance audit findings by common types for Pareto analysis.
The benefits of objective analysis of process safety audit data include more effective future audits and continuous process safety performance improvement at the site level.The presentation will include a brief review of the Microsoft Access database structure. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2011