bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cavitation and morphological changes in polypropylene deformed at elevated temperatures
Authors: Pawlak Andrzej , Galeski Andrzej 
Published: May 2010

AbstractPolypropylene (PP) thick films were subjected to tensile drawing at various temperatures from the room temperature to 100 °C. Morphological alterations during drawing were followed by wide‐angle X‐ray scattering, small‐angle X‐ray scattering, and scanning electron microscopy (SEM) of sectioned and etched samples, volume strain measurement, and light transparency measurement at various level of strain. The morphological observations were paralleled with stress–strain determination. Samples drawn at 25 and 40 °C undergo severe cavitation contributing to their volume increase up to 90–95%. The volume increase contributes greatly to the engineering strain. PP drawn at 70 and 100 °C does not cavitate. At the strain up to 1.2, a high lamellae orientation is observed in SEM, whereas the 2D WAXS patterns show in contrary circular diffraction rings indicating low orientation of crystals. The rotation of lamellae toward drawing direction is associated with reverse rotation of chains in crystals due to fine chain slips. These two rotations in opposite directions counterbalance resulting in a much weaker crystal orientation than expected from the SEM images. Noncavitating samples retain their translucency up to a high strain. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1271–1280, 2010
Preparation of conducting poly(vinyl chloride)/polyindole composites and freestanding films via chemical polymerization
Authors: Taylan Naciye Bihter , Sari Bekir , Unal Halil Ibrahim 
Published: May 2010

AbstractThis study covers the synthesis of conducting polyindole (PIN) homopolymer, poly(vinyl chloride)/polyindole (PVC/PIN) composites, and preparation of their freestanding films. PIN and composites were synthesized chemically by radicalic mechanism using FeCl3 as an initiator. Films of PVC and PVC/PIN composites were prepared by casting on glass Petri dishes. Mechanical properties of films were examined by stress–strain experiments. From FTIR spectra of polymers, it was revealed that polymerization reaction occurred by 2–3 mechanism. The conductivities of polymers at different temperatures were also measured by four‐probe technique and found in the range 10−4 to 10−5 S cm−1. Magnetic properties of the polymers were analyzed by Gouy scale measurements and were found that their conducting mechanisms are of polaron and bipolaron natures. Thermal properties of polymers were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and found that they had shown adequate thermal stability. X‐ray diffraction (XRD) spectra showed the amorphous nature of the polymers. Scanning electron microscopy (SEM) was used for microstructural analysis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1290–1298, 2010
Branched versus linear oligo(dimethylsiloxane): Differences in their thermodynamic interaction with solvents
Authors: Samadi Fatemeh , Eckelt John , Wolf Bernhard A. , Schüle Hanna , Frey Holger 
Published: May 2010

AbstractThe thermodynamic behavior of linear and of branched oligo(dimethylsiloxane) (O‐DMS) solutions was studied by means of vapor pressure measurements and vapor pressure osmometry at different temperatures for the thermodynamically favorable solvent THF. The branched material required for that purpose was synthesized and afterwards fractionated by means of the single solvent acetone to eliminate components of low degrees of branching. The Flory‐Huggins interaction parameters, χ, for the systems THF/O‐DMS as a function of composition pass a minimum at all temperatures (25, 40, and 60 °C) in the case of the branched material. For the unbranched oligomer such a minimum is only observed at 60 °C. At 40 °C the results are ambigous whereas the dependence is definitely linear at 25 °C. This exceptional behavior of the linear product at the latter temperature is tentatively attributed to the formation of favorable orientational order in the pure state under these conditions. At high oligomer concentrations THF interacts more favorably with the branched material, however, this preference is reversed upon dilution. All measured composition dependencies of χ can be modeled quantitatively by an approach accounting for chain connectivity and for the ability of the oligomers to change their conformation upon dilution. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1309–1318, 2010
An NMR investigation on the phase structure and molecular mobility of the novel exfoliated polyethylene/palygorskite nanocomposites
Authors: Li Wei , Jiang Binbo , Buda Alina , Wang Jingdai , Blümich Bernhard , Yang Yongrong , Zheng Jie 
Published: May 2010

AbstractNovel exfoliated polyethylene (PE)/palygorskite nanocomposites prepared by in situ polymerization are characterized by solid‐state nuclear magnetic resonance (NMR). The phase structure and molecular mobility are investigated by a combination of proton and carbon NMR. The results showed that incorporation of small amounts of palygorskite had great influence on the phase structure and molecular mobility. The incorporated palygorskite hindered the crystallization process and introduced motion‐hindered chains in the NMR crystalline and amorphous phase. 13C cross‐polarization and magic‐angle spinning NMR revealed two orthorhombic crystalline phase with different line‐width. The chain mobility of orthorhombic crystalline phase with broad resonance line is obviously hindered compared with the phase with narrow resonance line when the filler is introduced. Additionally, the results of pulsed field gradient NMR technique show those the tortuosities in the nanocomposites are much higher than that in the bulk PE. The self‐diffusion process of probe molecules is also influenced by the palygorksite load. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1363–1371, 2010
Expression of proteinase‐activated receptor‐2 (PAR2) is androgen‐dependent in stromal cell line (hPCPs) from benign prostatic hyperplasia
Authors: Mannowetz Nadja , Würdinger Robert , Zippel Andrea , Aumüller Gerhard , Wennemuth Gunther 
Published: May 2010

AbstractBACKGROUNDGrowth properties of the prostate are regulated by a variety of hormones and growth factors. Benign prostatic hyperplasia (BPH) is characterized by abnormal epithelial and stromal proliferation. Varying androgen hormone levels in elderly men are correlated with abnormal proliferations of the prostate. Proteinase‐activated receptor‐2 (PAR2), a subtype of G‐protein‐coupled receptors, is known to induce multiple biological processes. It could also play a key role in the proliferation and metastasis of prostate cancer, but its effect on BPH pathogenesis is to a great extent unknown.METHODSLocalization of PAR2 was determined both in pathologically altered and in normal prostate tissues by using immunohistochemical techniques. PAR2 activity was assessed by measuring changes in intracellular calcium [Ca2+]i following stimulation of cultured stromal cells with a PAR2 agonist (trypsin) and a synthetic PAR2‐activating peptide (AP). DHT‐dependence of PAR2 expression in prostate cancer and prostatic stromal cell lines was examined with semi‐quantitative and quantitative PCR. Cultured stromal cells (hPCPs) were stimulated with PAR2 AP and cell proliferation was determined through [3H]‐thymidine incorporation.RESULTSIn comparison to normal prostate, PAR2 expression was increased in BPH stroma. DHT induced a higher expression of PAR2 when sub‐physiological DHT‐levels were used. Higher levels of DHT produced reduced PAR2 expression. A mitogenic effect was induced by applying PAR2 AP to hPCPs‐cells.CONCLUSIONSIn conclusion, we found that PAR2 expression is hormone‐dependent in prostatic stromal cells with a negative correlation and we consider it to be an important factor in mitogenesis in BPH. Prostate 70:1350–1358, 2010. © 2010 Wiley‐Liss, Inc.
An in vitro model for preclinical testing of endocrine therapy combinations for prostate cancer
Authors: Pfeiffer Minja J. , Mulders Peter F. , Schalken Jack A. 
Published: May 2010

AbstractBACKGROUNDEven though patients with prostate cancer commonly respond to endocrine treatment, in most cases the disease progresses to castration resistant prostate cancer (CRPC). Our objective was to generate a novel cell line model representing the endocrine treatment naive prostate cancer for testing treatments that target the androgen receptor (AR) and androgen metabolism.METHODSAfter culturing DuCaP cells 20 passages with additional 1 nM R1881, DuCaP‐N(aive) cell line was developed and validated for testing endocrine therapy combinations. Cell viability, apoptosis and cell cycle distribution were assessed in DuCaP and DuCaP‐N when interfering with the hormonal content.RESULTSAddition of 1 nM R1881 to DuCaP reduces cell viability and induces cell cycle inhibition and apoptosis. Eventually, an androgen accustomed DuCaP‐N cell line developed. An antiandrogen (bicalutamide), a histone deacetylase (HDAC) inhibitor (trichostatin A) and a 5α‐reductase (SRD5A) inhibitor (finasteride) reduce cell viability, and their combinations give a synergistic response in inducing apoptosis.CONCLUSIONSThe TMPRSS2‐ERG expressing DuCaP‐N cell line represents human prostate cancer prior to endocrine treatment, and its parental DuCaP cell line is a model for CRPC. These cell lines can be used for preclinical evaluation of compounds that target the androgenic pathway. Prostate 70: 1524–1532, 2010. © 2010 Wiley‐Liss, Inc.
Thermodynamics of phosphotyrosine peptide–peptoid hybrids binding to the p56lck SH2 domain
Authors: Dekker F. J. , DE Mol N. J. , Liskamp R. M. J. 
Published: May 2010

AbstractA frequently used approach to transform peptides into more drug‐like compounds is preparation of the corresponding peptoids or peptide–peptoid hybrids. Although peptoids have advantages, there may also be some disadvantages such as their increased flexibility and the reduced ability for hydrogen bond formation due to alkylation of the backbone amide nitrogen, which might affect the free Gibbs energy (ΔG). To obtain more insight into these contributions to ΔG, we performed thermodynamic analyses on the interaction between peptide–peptoid hybrids, based on the sequence ‐pTyr‐Glu‐Glu‐Ile‐, and the p56lck (Lck) Src homology 2 domain. van't Hoff analysis was performed on binding data obtained from surface plasmon resonance competition experiments in a temperature range of 10–40 °C. It is observed that amino acid–peptoid substitutions do not have a systemic negative effect on the entropic contributions to ΔG. However, loss in hydrogen‐bonding capacity of the backbone may strongly reduce the binding enthalpy and contribute to the observed lower binding affinity. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Optical phonons in colloidal CdSe nanorods
Authors: Lange Holger , Mohr Marcel , Artemyev Mikhail , Woggon Ulrike , Niermann Tore , Thomsen Christian 
Published: May 2010

AbstractIn this work the vibrational properties of colloidal CdSe nanorods (NRs) and CdSe‐ZnS core–shell NRs are investigated via Raman spectroscopy. The longitudinal optical (LO) phonons in NRs are confined to the NR volume. The confinement of the phonon wave function leads to a relaxation of the q = 0 rule and the phonon frequency is found to depend on the NR diameter. The coupling strength between LO phonons and excitons also depends on the NR diameter. The total coupling strength is much lower than in bulk material due to a decrease of the influence of the Coulomb interaction in nanoparticles. However, the coupling strength is found to rise for decreasing diameters. This is due to the increasing contributions of higher frequency phonons for smaller nanoparticle sizes. A radial breathing mode with a diameter dependent frequency is deduced from ab initio calculations and its existence in NRs is verified experimentally. The diameter‐dependence of the modes' frequency can be used to estimate the NR diameter from a Raman measurement. In core–shell structures, the lattice mismatch between core and shell leads to a compressive strain of the core lattice. The exciton wave function changes with the modified boundary. This is reflected in an altered exciton–phonon coupling strength.
Spontaneous polarization in III‐nitride materials: crystallographic revision
Authors: Karpov Sergey Yu. 
Published: May 2010

AbstractA simple model for estimation of spontaneous polarization in III‐nitride compounds is suggested, utilizing the data on the materials lattice constants normally measured with sufficient accuracy. The model is applied to reconsider the spontaneous polarization in AlN, GaN, InN, and their alloys. The results are compared with those obtained by ab initio simulations. Polarization charges at the AlGaN/GaN and InGaN/GaN interfaces are calculated and compared with available data. The model can be easily extended to other wurtzite compounds and their alloys. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Observation and quantification of the direction reversal of the surface band bending in GaAs1‐xNx using terahertz electromagnetic wave and photoreflectance measurements
Authors: Takeuchi Hideo , Yanagisawa Junichi , Hashimoto Jun , Nakayama Masaaki 
Published: May 2010

AbstractWe have investigated the polarity of terahertz (THz) electromagnetic waves from a GaAs1‐xNx epitaxial layer with x = 0.43% to clarify the effects of nitrogen incorporation on the direction of the surface band bending. The THz‐wave polarity of the GaAs1‐xNx sample is reversed compared with that of an i ‐GaAs/n ‐GaAs sample that has an upward surface band bending; namely, the GaAs1‐xNx sample has a downward band bending. The polarity reversal is attributed to the phenomenon that the conduction band bottom is lowered by the band anticrossing due to the nitrogen incorporation, which changes the direction of the surface band bending. We also measured the photoreflectance (PR) spectrum of the GaAs1‐xNx sample to quantify the surface electric field produced by the surface band bending. The PR spectrum exhibits the Franz‐Keldysh oscillations (FKOs) from the GaAs1‐xNx layer. From the FKOs, the surface electric field is estimated to be 24 kV/cm. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sublimation growth of bulk crystals of AlN‐rich (AlN)x(SiC)1–x solid solutions
Authors: Bickermann Matthias , Filip Octavian , Epelbaum Boris M. , Heimann Paul , Winnacker Albrecht 
Published: May 2010

Abstract(AlN)x(SiC)1–x bulk single crystals are prepared by sublimation growth employing an AlN source placed in a tantalum carbide container. A 6H ‐SiC substrate acts both as seed and as source for silicon and carbon species. As the growth temperature is increased from 1900°C to 2050°C or the seed surface orientation is changed from (0115) to (0001), crystal coloration changes from yellowish to greenish to blackish. We attribute the change in coloration to an increasing Si/C content in the samples and estimate that up to 10% at of Si and C are incorporated. Accompanying changes in below band‐gap optical absorption and cathodoluminescence are discussed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of bulk‐like GaN nanorods grown on Si(111) substrates by rf‐plasma assisted molecular beam epitaxy
Authors: Park Young S. , Kang T. W. , Im Hyunsik , Holmes Mark J. , Taylor Robert A. 
Published: May 2010

AbstractWe have investigated the optical properties of bulk‐like GaN nanorods by cathodoluminescence measurements at room temperature. The bulk‐like nanorods were grown on a Si (111) substrate by rf‐plasma assisted molecular beam epitaxy and are characterized be being surrounded by a compact region. A weak and broad emission line near 3.36 eV was observed at an accelerating voltage of 5 kV. This emission occurs at a lower energy than the emission from unstrained GaN nanorods that protrude from the compact region. Upon increasing the electron beam energy, and hence investigating regions deeper in the sample, the peak emission energy redshifts due to the strain at the substrate interface. The behaviour of the emission line is further investigated with cathodoluminescence measurement on single nanorod's (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non‐equilibrium GaNAs alloys with band gap ranging from 0.8‐3.4 eV
Authors: Yu K. M. , Novikov S. V. , Broesler R. , Staddon C. R. , Hawkridge M. , Liliental‐Weber Z. , Demchenko I. , Denlinger J. D. , Kao V. M. , Luckert F. , Martin R. W. , Walukiewicz W. , Foxon C. T. 
Published: May 2010

AbstractA new alloy system, the GaN1‐xAsx alloys in the whole composition range was successfully synthesized using the non‐equilibrium low temperature molecular beam epitaxy method. The alloys are amorphous in the composition range of 0.17 < x < 0.75 and crystalline outside this region. The amorphous films have smooth morphology, homogeneous composition and sharp, well defined optical absorption edges. The bandgap energy varies in a broad energy range from ∼3.4 eV in GaN to∼0.8 eV at x∼0.85. The reduction of the band gap can be attributed primarily to the downward movement of the conduction band for alloys with x > 0.2, and to the upward movement of the valence band for alloys with x < 0.2. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
RF‐MBE growth of InN on 4H‐SiC (0001) with off‐angles
Authors: Orihara Misao , Takizawa Shin , Sato Takanori , Ishida Yuuki , Yoshida Sadafumi , Hijikata Yasuto , Yaguchi Hiroyuki 
Published: May 2010

AbstractWe have grown InN on 4H‐SiC (0001) substrates with various off‐angles by RF‐N2 plasma molecular beam epitaxy (RF‐MBE). Scanning electron microscope observation revealed that InN films grown on 4H‐SiC (0001) substrates with off‐angles of 4° and 8° are very smooth and that there are no voids which have often observed for InN epitaxial layers. X‐ray diffraction reciprocal space maps for InN grown on 4H‐SiC (0001) showed that the c‐axes of InN grown on 4H‐SiC 4° and 8° off substrates are inclined by 0.35° and 0.8°, respectively, toward the misorientation of the substrate while the c‐axis of InN is parallel to that of 4H‐SiC for the on‐axis substrate. Strong PL peak was observed from InN grown on 4° off substrate at 0.68 eV at 15 K. The PL peak was clearly observed even at room temperature and simply shifted to lower energies with increasing temperature. The difference in the PL peak energy between at 15 K and 300 K was 20 meV, which is reasonable taking into account the difference in the thermal coefficients of InN and SiC (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The nucleation of HCl and Cl2‐based HVPE GaN on mis‐oriented sapphire substrates
Authors: Bohnen Tim , van Dreumel Gerbe W. G. , Weyher Jan L. , van Enckevort Willem J. P. , Ashraf Hina , de Jong Aryan E. F. , Hageman Paul R. , Vlieg Elias 
Published: May 2010

AbstractThe nucleation of both classic HCl‐based and novel Cl based HVPE GaN on mis‐oriented sapphire substrates was investigated. The use of Cl2in HVPE increases the growth rate by a factor of 4‐5 and strongly reduces the parasitic deposition, allowing for the growth of much thicker wafers than HCl‐based HVPE. Morphological SEM surface studies of the HCl‐based HVPE sample surface show that at 600 °C a nanocrystalline layer is deposited on the sapphire. During the subsequent annealing phase, the morphology changes to a μm‐sized island structure. During overgrowth at 1080 °C, the islands coalesce. Small voids or pinholes are then formed in between the coalescing GaN islands. These pinholes lead to numerous pits on the surface of the GaN at thicknesses of 5 μm. The pits disappear during continued overgrowth and can no longer be found on the surface, when the GaN film reaches a thickness of 45 μm. This particular coalescence mechanism also applies to Cl2‐based HVPE GaN on sapphire (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoelectrochemical application of GaN nanostructures on Si for hydrogen generation by water reduction
Authors: Fujii Katsushi , Kato Takashi , Sato Keiichi , Im Inho , Chang Jiho , Yao Takafumi 
Published: May 2010

AbstractGaN nanostructures grown on n‐type Si (111) substrate were applied as photo‐illuminated working electrodes for photoelectrochemical water splitting. Photocurrent density increased with the density of GaN nanodots. The photocurrent density was, however, quite small compared to that of GaN nanorods and decreased with treated time. The current density of GaN nanorods was stable probably because the nanorod crystalline size was larger than that of the nanodots. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Assessing consistent treatment effect in a multi‐regional clinical trial: a systematic review
Authors: Chen Joshua , Quan Hui , Binkowitz Bruce , Ouyang S. Peter , Tanaka Yoko , Li Gang , Menjoge Shailendra , Ibia Ekopimo ,   for the Consistency Workstream of the PhRMA MRCT Key Issue Team
Published: May 2010

AbstractA key issue in multi‐regional clinical trials (MRCTs) is how to assess the consistency of treatment effect across regions, although there is no a priori reason to believe that the treatment effect should vary across the regions. In this article, we define the research question as an assessment of overall consistency across all regions for which all regions are considered equally important. This is different from the region/country‐specific analyses (e.g. US vs Non‐US), which are frequently requested by local regulatory agencies and usually performed for multiple agencies. We provide a systematic review of methods that may potentially be used for assessing consistency across regions, including commonly used quantitative/qualitative interaction tests, Japanese Pharmaceutical Medical Device Agency (PMDA) Methods 1 & 2, and those proposed for different purposes (e.g. bridging studies, meta‐analysis, and vaccine lot consistency, among others). These methods are classified into three groups: global methods, multivariate quantitative methods, and multivariate qualitative methods. A case study is used to illustrate these methods. We also provide recommendations on how to choose appropriate methods and incorporate them in the study design. Copyright © 2010 John Wiley & Sons, Ltd.
Accurate mass measurement by matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry. I. Measurement of positive radical ions using porphyrin standard reference materials
Authors: Griffiths Nia W. , Wyatt Mark F. , Kean Suzanna D. , Graham Andrew E. , Stein Bridget K. , Brenton A. Gareth 
Published: May 2010

AbstractA method for the accurate mass measurement of positive radical ions by matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOFMS) is described. Initial use of a conjugated oligomeric calibration material was rejected in favour of a series of meso‐tetraalkyl/tetraalkylaryl‐functionalised porphyrins, from which the two calibrants required for a particular accurate mass measurement were chosen. While all measurements of monoisotopic species were within ±5 ppm, and the method was rigorously validated using chemometrics, mean values of five measurements were used for extra confidence in the generation of potential elemental formulae. Potential difficulties encountered when measuring compounds containing multi‐isotopic elements are discussed, where the monoisotopic peak is no longer the lowest mass peak, and a simple mass‐correction solution can be applied. The method requires no significant expertise to implement, but care and attention is required to obtain valid measurements. The method is operationally simple and will prove useful to the analytical chemistry community. Copyright © 2010 John Wiley & Sons, Ltd.