bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of electric field parameters on the resistivity and induced percolation time of carbon black‐filled polystyrene composites
Authors: Tang Lina , Yan Xiaohu , Kontopoulou Marianna , Docoslis Aristides 
Published: May 2011

AbstractThe present work examines the influence of externally applied alternating current (AC) electric fields on the formation of electrically conducting structures in carbon black/polystyrene (CB/PS) composites. It is shown that AC electric fields are capable of producing electrically conducting composites at filler concentrations substantially lower than the composite's percolation threshold by causing filler attraction and alignment into columnar structures with orientation normal to the electrode surface. The times required for the insulator‐to‐conductor transition (termed “percolation times”) in these CB/thermoplastic composites are measured as a function of important process parameters, such as applied voltage, electric field frequency, and filler concentration. The percolation times are shown to be inversely proportional to both the square root of the applied field intensity and to the power of 0.3 of the filler concentration, while they appear to be independent of AC field frequencies in the range 10 Hz to 10 KHz. These empirical scaling laws can be used as a guide for the selection of experimental conditions in future studies on electrified composites or for the selection of processing parameters in composites manufacturing. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Fetal RHD genotype detection from circulating cell‐free fetal DNA in maternal plasma in non‐sensitized RhD negative women
Authors: Bombard Allan T. , Akolekar Ranjit , Farkas Daniel H. , VanAgtmael Anna L. , Aquino Frank , Oeth Paul , Nicolaides Kypros H. 
Published: May 2011

AbstractObjectiveTo examine the performance of the SensiGene Fetal RHD Genotyping Laboratory Developed Test (RHD Genotyping LDT) using circulating cell‐free fetal DNA (ccff DNA) extracted from maternal plasma.Methodsccff DNA was extracted from maternal blood from non‐sensitized women with singleton pregnancies in two cohorts, one with a serotype reference (11–13 weeks' gestation) and one with the reference source (6–30 weeks' gestation). The presence of three RHD exon sequences (exons 4, 5, 7), the psi‐pseudogene, three Y‐chromosome sequences (SRY, DBY and TTTY2), and the X/Y‐chromosome TGIF gene control were determined using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry—the RHD Genotyping LDT.ResultsThe cohort with a serotype RhD reference showed correct classification in 201 of 207 patients, a test accuracy of 97.1%, with a sensitivity and specificity for prediction of RhD serotype of 97.2 and 96.8%, respectively. The cohort with a genotype RHD reference showed correct classification in 198 of 199 patients, indicating a test accuracy of 99.5% with a sensitivity and specificity for prediction of RHD genotype of 100.0 and 98.3%, respectively.ConclusionFetal RHD genotyping can accurately be determined using ccff DNA in the first and second trimesters of pregnancy. Copyright © 2011 John Wiley & Sons, Ltd.
Preparation of polybenzimidazole/functionalized carbon nanotube nanocomposite films for use as protective coatings
Authors: Zhang Li , Ni Qing‐Qing , Shiga Akihiko , Natsuki Toshiaki , Fu Yaqin 
Published: May 2011

AbstractFunctionalized multi‐walled carbon nanotubes (MWCNTs) via microwave‐induced polymerization modification route, and polybenzimidazole (PBI) nanocomposite films containing 0.1‐5 wt% functionalized MWCNTs were successfully synthesized. The functionalized MWCNTs were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and X‐ray photoelectron spectroscopy (XPS). The results verify that the polymer was successfully grafted to the MWCNTs with a polymer layer that was several nanometers thick. The TGA results showed that the quantity of the attached polymer reached approximately 9.4 wt%. The mechanical properties of the nanocomposite films were measured by tensile test and dynamic mechanical analysis (DMA). The tensile test results indicated that the Young's modulus increased by about 43.9% at 2 wt% CNT loading, and further modulus growth was observed at higher filler loading. The DMA studies indicated that the nanocomposite films had a higher storage modulus than pure PBI film in the temperature range of 30‐300°C, and the storage modulus was maintained above 0.82 GPa. Simulation results confirmed that the PBI nanocomposite films had desirable mechanical properties for use as a protective coating. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.
Stabilizer thickness profiles in polyethylene pipes transporting drinking water disinfected by bleach
Authors: Colin X. , Verdu J. , Rabaud B. 
Published: May 2011

AbstractPolyethylene connection pipes of wall thickness ranging from 3.0 to 4.5 mm, used for 0, 5, 9, 12, and 18 years in the French network of drinking water disinfected by bleach, have been analyzed. The stabilizer thickness profiles reveal that bleach destroys the stabilizer in a superficial layer of about 0.5 mm depth at the water–polymer interface. In the rest of the wall, stabilizer is lost by physical processes, i.e., transport by diffusion into the bulk, extraction at the water–polymer interface, and evaporation at the polymer–air interface. The whole loss kinetics is governed by extraction and evaporation. The classical scheme for evaporation–diffusion process has been used to model physical loss processes, but with boundary conditions different from the literature ones. Concerning chemical aspects, some mechanisms proposed in the literature are criticized. The identification of the bleach reactive species remains an open question. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.
CO2‐derived latent nitrogen nucleophiles for controlled cross‐linking of brominated poly(isobutylene‐co‐isoprene)
Authors: Faba Michael A.J. , Parent J. Scott , Whitney Ralph A. 
Published: May 2011

AbstractNew methods for preparing thermoset elastomer products from brominated poly(isobutylene‐co‐isoprene) (BIIR) are described, wherein control of cross‐linking dynamics is gained using latent forms of ammonia, primary amines, and cyclic amidines. BIIR cross‐linking by repeated alkylation of standard nitrogen nucleophiles is too rapid at standard polymer processing temperatures, whereas CO2‐derived salts are shown to be sufficiently inactive under these conditions to support conventional BIIR compounding. Examples include the carbonate, bicarbonate and carbamate salts of ammonia; carbamate and carbamate esters of hexadecyl amine; and the bicarbonate salt of 1,8‐diazabicyclo[5.4.1]undec‐7‐ene. Thermal decomposition of these latent curatives releases CO2 and the desired nucleophile to support high cross‐linking rates and yields at standard cure temperatures. Thermogravimetric analysis of salt decomposition, rheological measurements of cross‐link density, and spectroscopic analysis of polymer dehydrohalogenation products are used to define the relationship between latent nucleophile activation and BIIR cure dynamics. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.
Micellar polymerization, characterization, and viscoelasticity of combined thermally insensitive terpolyacrylamides
Authors: Rodríguez Fátima Pérez , Jiménez‐Regalado Enrique J. 
Published: May 2011

AbstractPolymer chains consisting of water‐soluble polyacrylamides and N‐isopropylacrylamide (NIPAM), hydrophobically modified with low amounts of N,N‐dialkylacrylamides (N,N‐dioctylacrylamide) have been prepared via free radical micellar polymerization, using a hydrophobic initiator derived from 4,4′‐azobis(4‐cyanopentanoic acid) containing a long linear chain of 16 (C16) carbon atoms. This procedure resulted in polyacrylamides containing hydrophobic groups along the chain as well as at the chain ends. These polymers are named “combined associative polymers” and include within their structure a water‐soluble monomer (acrylamide), a thermosensitive monomer (NIPAM) and a hydrophobic monomer. The polymers were characterized by different techniques, also studying the effect of adding a surfactant anion such as sodium dodecylsulfate. The viscoelastic properties as a function of temperature of these associative polymers were investigated using steady‐flow and oscillatory experiments considering the relaxation time (TR) and the plateau modulus (G0). The effect of concentration of acrylamide and NIPAM on the viscosity of the associative polymer solutions was investigated. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
The preparation of 3,6‐bis(3‐hexylthien‐2‐yl)‐s‐tetrazine and its conjugated polymers
Authors: Ding Jianfu , Li Zhao , Cui Zhe , Robertson Gilles P. , Song Naiheng , Du Xiaomei , Scoles Ludmila 
Published: May 2011

AbstractWe demonstrated, for the first time, that 3,6‐bis(3‐hexylthien‐2‐yl)‐s‐tetrazine (TTz) with hexyl group at the 3‐position of thiophene rings can be prepared using a modified sulfur‐assisted Pinner synthesis. Although the hexyl group creates large steric hindrance to the tetrazine ring formation reaction, and the reaction under a traditional condition only produces trace amount of the target product, the yield of this reaction under a modified reaction condition using anhydrous hydrazine at 68 °C can reach 65%. Two new copolymers of the resulting TTz and hexyl‐ or 2‐ethylhexyl‐substituted cyclepentadithiophene have been prepared. The polymers show a broader light absorption in film than in solution attributing to the large distribution of effective conjugation length of polymer chain due to the existence of both cis‐ and trans‐orientations of the 3‐hexylthiophene units in the planar polymer chain in solid state. Although the polymers show a narrow band gap and a deep HOMO level, which are desirable for generating an efficient light absorption and a larger open circuit voltage (Voc) of the resulting solar cell devices, the device performance is not as good as expected. It is attributed to the random distribution of the cis‐ and trans‐conformations along the polymer chain. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.
Unequal siblings: Adverse characteristics of naphtalene‐based hoveyda‐type second generation initiators in ring opening metathesis polymerization
Authors: Leitgeb Anita , Szadkowska Anna , Michalak Michal , Barbasiewicz Michał , Grela Karol , Slugovc Christian 
Published: May 2011

AbstractA family of four different Hoveyda‐type initiators bearing a π‐extended carbene ligand was characterized regarding the activity in ring opening metathesis polymerization. One of the initiators shows high activity at ambient temperature, similar to the second generation Hoveyda–Grubbs catalyst and is even suited for the controlled polymerization of certain norbornene derivatives. The other family members exhibit a pronounced latency at room temperature, and polymerization can be triggered by heat. The scope of these initiators in the thermally triggered polymerizations of norbornene derivatives in general and dicyclopentadiene in particular was disclosed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.
Research progress in toughening modification of poly(lactic acid)
Authors: Liu Hongzhi , Zhang Jinwen 
Published: May 2011

AbstractRenewable poly(lactic acid) (PLA) exhibits high strength and stiffness. PLA is fully biodegradable and has received great interest. However, the inherent brittleness of PLA largely impedes its wide applications. In this article, the recent progress in PLA toughening using various routes including plasticization, copolymerization, and melt blending with flexible polymers, was reviewed in detail. PLA toughening, particularly modification of impact toughness through melt blending, was emphasized in this review. Reactive blending was shown to be especially effective in achieving high impact strength. The relationship between composition, morphology, and mechanical properties were summarized. Toughening mechanisms were also discussed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011.
Light scattering and transmission studies of nanofiller particulate size, matrix cavitation, and high strain interfacial dewetting behavior in silica‐elastomer composites
Authors: Tunnicliffe Lewis B. , Thomas Alan G. , Busfield James J. C. 
Published: May 2011

AbstractThe effect of silica nanofiller surface chemistry on compounded particle size and high strain particle dewetting in a semitransparent nanosilica‐filled elastomer composite was determined using backscattered visible light and transmitted light, respectively. The integrated intensities of backscattered light from the samples were collected at various visible wavelengths for thin‐film composites using ultraviolet–visible spectrometer with an integrating sphere. The data revealed strong Rayleigh‐type scattering from compounded filler particles. Size information was extracted and found to broadly correlate with scanning electron microscopy image analysis of fracture surface. Incorporation of a siloxane surface treatment chemical during compounding resulted in a reduced average filler particle size in the cured composite. On extension of the samples, an optical transition was observed only in the filled composites. At high strains, the semi transparent samples displayed an abrupt drop in transparency becoming opaque. This was quantified using a simple light transmission‐sample extension technique. Strain‐induced crystallization was discounted as the cause for the transition by X‐ray diffraction analysis. The onset yield stress for the optical transition was found to be filler surface‐chemistry‐dependent with the siloxane‐treated filler exhibiting a greatly increased onset stress value. These observations were discussed and rationalized in terms of filler particle–matrix dewetting and cavitation at high strains. Matrix–filler dewetting was distinguished from matrix cavitation by comparison with Beer–Lambert behavior derived from unstrained samples. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011.
Preoperative serum levels of early prostate cancer antigen (EPCA) predict prostate cancer progression in patients undergoing radical prostatectomy
Authors: Zhao Zhigang , Ma Wenjing , Zeng Guohua , Qi Defeng , Ou Lili , Liang Yeping 
Published: May 2011

AbstractBACKGROUNDEarly prostate cancer antigen (EPCA) has been shown a prostate cancer (PCa)‐associated nuclear matrix protein, however, its serum status and prognostic power in patients with PCa are unknown. The goals of this study are to measure preoperative serum EPCA levels in a cohort of PCa patients who were treated with radical prostatectomy (RP), and to investigate whether serum EPCA levels would independently predict cancer prognosis after the surgery.METHODSThe study group consisted of 109 consecutive patients with clinically localized PCa who were candidates for RP. Serum EPCA levels were measured by ELISA prior to the surgery, and were correlated with pathologic parameters and clinical outcomes postoperatively.RESULTSA total of 106 patients underwent RP. Preoperative mean serum EPCA level in RP patients (15.84 ± 3.63 ng/ml) was significantly higher than that in healthy subjects (4.62 ± 1.15 ng/ml) (P < 0.001), but serum EPCA levels in the both groups were statistically lower than the levels in patients with PCa metastatic to regional lymph nodes (27.83 ± 6.22 ng/ml) and metastatic to bone (28.50 ± 6.67 ng/ml) (all P's < 0.001). In patients who progressed during follow‐up, preoperative serum mean EPCA levels were higher in those with aggressive disease progression (27.64 ± 5.48 ng/ml) compared with nonaggressive disease progression (18.15 ± 4.63 ng/ml; P < 0.001). In pre‐ and postoperative multivariate analyses, preoperative serum EPCA level was an independent predictor for disease progression (Hazards Ratio = 5.016, P < 0.001 and Hazards Ratio = 4.305, P < 0.001, respectively).CONCLUSIONSPreoperative serum EPCA level is significantly elevated in localized PCa patients with metastatic disease and strongly predicts cancer progression postoperatively. Prostate 72:270–279, 2012. © 2011 Wiley Periodicals, Inc.
Androgens repress expression of the f‐box protein Skp2 via p107 dependent and independent mechanisms in LNCaP prostate cancer cells
Authors: Jiang Jingting , Pan Yunqian , Regan Kevin M. , Wu Changping , Zhang Xueguang , Tindall Donald J. , Huang Haojie 
Published: May 2011

AbstractBACKGROUNDAndrogens control homeostasis of the normal prostate and growth of prostate cancer (PCa) through the androgen receptor (AR) by regulating gene networks involving in cell proliferation, differentiation, and survival. We demonstrated previously that expression of Skp2, a key protein regulating cell entry into the S phase, is inhibited by androgens in an AR‐dependent manner (Oncogene, 2004; 23(12): 2161–2176). However, the underlying mechanism of this regulation is unknown.METHODSUsing the LNCaP PCa cell line as a working model, the effect of androgens on the expression of Skp2 was examined by Western and Northern blot analyses. Cell cycle was measured by fluorescence‐activated cell sorting (FACS). Gene transfection was performed by electroporation to manipulate the expression levels of proteins studied.RESULTSAt physiological levels androgens markedly repressed Skp2 expression but slightly induced Skp2 expression at subphysiological levels. Androgens modestly decreased the stability of the Skp2 protein. Androgenic repression of Skp2 expression was completely abolished by E1A‐mediated inactivation of pocket proteins including RB, p130, and p107. Moreover, ectopic expression of p107 inhibited Skp2 expression, and silencing of p107 partially blocked androgenic repression of Skp2.CONCLUSIONSOur data indicate that androgens repress Skp2 expression via p107‐dependent and ‐independent pathways in PCa cells. These regulatory mechanisms may be targeted for the development of new therapeutics of androgen‐refractory PCa. Prostate 72:225–232, 2012. © 2011 Wiley Periodicals, Inc.
Microstructure characterization of ball‐milled Ni50Co50 alloy by Rietveld method
Authors: Loudjani Nadia , Bensebaa Nadia , Alleg Safia , Djebbari Chaffia , Greneche Jean Marc 
Published: May 2011

AbstractA nanostructured Ni50Co50 mixture was prepared by high‐energy ball milling in a planetary ball mill (Frisch P7) under an argon atmosphere. Scanning electron microscopy and X‐ray diffraction (XRD) have been used to study the morphology of the powder particles, microstructure, and structure evolution. Detailed analysis of the XRD patterns was performed by the MAUD program, which is based on the Rietveld method. It reveals the complete vanishing of the Co peaks after 3 h of milling, indicating the allotropic transformation of Co from hcp to fcc structure. The reciprocal dissolution of the elemental Ni and Co powders leads to the formation of a heterogeneous solid solution with two structures: fcc‐Ni(Co) and fcc‐Co(Ni) with relative fractions of about 76 and 20%, respectively, after 24 h of milling. Microstructural parameters such as lattice parameter, crystallite size, microstrains, dislocation density, and stacking faults have been deduced from the best Rietveld refinements. The formation kinetics of nanostructured Ni50Co50 mixture can be described by a lower Avrami parameter, n, close to 0.34.
Physisorption of cis‐ and trans‐decalin on Pt4 clusters from density functional theory calculations
Authors: Yu Shengping , Zeng Qun , Yang Shengyong , Yang Mingli 
Published: May 2011

AbstractThe adsorption of cis‐ and trans‐decalin on Pt4 clusters was investigated using density functional theory calculations. A number of low‐lying Pt4–decalin isomers were identified with an extensive structure screening. Typical physisorption of trans‐ and cis‐decalins on Pt4 surfaces was noted. The geometrical and electronic properties of Pt4 clusters are subjected to minor changes upon decalin adsorption. The rhombus Pt4 structures are found in most of the low‐lying isomers, while the tetrahedral and square Pt4 appear in a few individuals. Trans‐ and cis‐decalins behave similarly in the adsorption although the Pt4–trans‐decalin complexes are slightly more stable than the corresponding Pt4–cis‐decalin isomers. Three main adsorption patterns distinguished with the number and circumstance of Pt atom(s) and H atoms in decalin are characterized among the low‐lying isomers. The revealed Pt4–decalin interaction patterns could be useful for future study of dehydrogenation and cracking reactions of cycloalkanes catalyzed by Pt nanoclusters.
A CASSCF/CASPT2 study on the low‐lying electronic states of the CH3SS and its cation
Authors: Song Ming‐Xing , Zhao Zeng‐Xia , Zhang Wei , Bai Fu‐Quan , Zhang Hong‐Xing , Sun Chia‐Chung 
Published: May 2011

AbstractComplete active space self‐consistent field (CASSCF) and multiconfiguration second‐order perturbation theory (CASPT2) calculations with contracted ANO‐RCC basis set were performed for low‐lying electronic states of CH3SS and its cation in Cs symmetry. For the ground state X2A″ of CH3SS, the calculated S‐S stretching mode is in good agreement with experimental reports. The electron transitions of CH3SS+, X1A′ → 11A″, X1A′ → 21A′, and X1A′ → 21A″, are predicted at 1.055, 3.247, and 3.841 eV. Moreover, the calculated adiabatic and vertical ionization potential and adiabatic affinity are in reasonable agreement with the experimental data. The CASSCF/CASPT2 potential energy curves (PECs) were calculated for S2‐loss dissociation from the X2A″, 12A′, and 22A″ states. The electronic states of the CH3 radical and S2 molecule as the dissociation products were carefully determined by checking energies and geometries of the asymptote products. The S2‐loss PEC for CH3SS indicate that S2‐loss dissociation occurs from the X2A″ state leading to CH3 (12A″) + S2 (X3Σ), the 12A′ and 22A″ leading to CH3 (12A″) + S2 (1Δg). © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012.
A benchmark quantum Monte Carlo study of the ground state chromium dimer
Authors: Hongo Kenta , Maezono Ryo 
Published: May 2011

AbstractWe report calculations of the ground state energy and binding curve of the chromium dimer using the variational and diffusion quantum Monte Carlo (VMC and DMC) methods. We examined various single‐determinant and multideterminant wavefunctions multiplied by a Jastrow factor as a trial/guiding wavefunction for VMC/DMC. The molecular orbitals in the single determinants were calculated using restricted or unrestricted Hartree–Fock or density functional theory (DFT) calculations where five commonly used local (SVWN5), semilocal (PW91 and BLYP), and hybrid (B1LYP and B3LYP) functionals were examined. The multideterminant expansions were obtained from the generalized valence bond and (truncated) unrestricted configuration interaction with single and double excitations (UCISD) methods. We also examined a UCISD wavefunction in which UCISD expansions were added to the UB3LYP single‐determinant reference, and their coefficients were optimized at the VMC level. In addition to the wavefunction dependence, the effects of pseudopotentials and backflow transformation were also investigated. The UB3LYP single‐determinant and multideterminant wavefunctions were found to give the variationally best DMC energies within the framework of single‐determinant and multideterminants, respectively, though both the DMC energies were higher than twice the DMC atomic energy. Some of the VMC binding curves show a flat or quite shallow well bottom, which gets recovered deeper by DMC. All the DMC binding curves have a minimum indicating a bound state, but the unrestricted ones overestimate the equilibrium bond length. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012