bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epoxy networks modified by unsaturated oligoesters and acrylates or methacrylates
Authors: Bratychak Mihailo , Brostow Witold , Yatczyshyn Yozef 
Published: March 2011

AbstractWe have studied the formation of networks on the basis of an epoxy resin called ED‐20, the same resin modified with tert ‐butylhydroperoxide (called ED‐20P), unsaturated oligoesters and polyethylenepolyamine in the presence of acrylates and methacrylates at 20°C, 100°C and 130°C. The gel‐fraction contents in the blends and the pendulum damping hardness of films made from the blends have been determined. The progress of gelation has been related to the composition, time and crosslinking temperature. The presence of peroxide groups enhances the extent of gelation. When those groups are present, acrylates and methacrylates provide still higher values of the ultimate gel fractions, acting as diluents (lowering viscosity of the initial blends) and simultaneously as crosslinking agents. The pedulum damping hardness tests for organic films performed as a function of time provide results parallel to those obtained by the gel fraction determination via Soxhlett extraction with acetone. Thus, both methods can be used to pursue the progress of gelation.
Properties of in‐situ filled polyethylene
Authors: Bolz Andreas , Hess Michael , Veeman Wiebren S. 
Published: March 2011

AbstractPolyethylene‐filler composites (kaolin, BaSO4, and TiO2) have been prepared by in‐situ polymerization using a metallocene catalyst and by extrusion mixing in the melt. TiO2 influences the polymerization process. In‐situ polymerization was found to be advantageous with respect to encapsulation, dispersion of the filler particles leading to improved mechanical properties, except for TiO2 containing composites. No significant influence on crystallization was observed.
Biodegradation of poly (vinylalcohol) with enzymatic extracts of phanerochaete chrysosporium
Authors: Mejía G. Amanda Inés , López O. Betty Lucy , Mulet P. Antonio 
Published: March 2011

AbstractCommercial poly(vinylalcohol) samples (PVOH) of average molecular mass (Mw) 120,000 g/mol, were subjected to biodegradation with enzymatic extracts of the Phanerochaete chrysosporium fungus, in which the lignine peroxidase activity (LiP) was detected. The results of differential refractive index and ultraviolet (UV) absorption Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography coupled to a Mass Detector (GC‐MS) allow to deduce that in 15 days, under the conditions of this study, the average molar mass of the polymer decreases in 79.3 %. The benzaldehyde was detected as the main degradation product.
Mobility and orientation of semi‐rigid polyesters
Authors: Baxmann Rita , Hess Michael , Woelke Ralf , Veeman Wiebren 
Published: March 2011

AbstractMobility and orientational behavior of semi‐flexible polyesters from diphenyl‐dicarbonic acid and some branched propyl‐and butyl spacers have been investigated using static NMR techniques. Increasing molar mass of the polymers was found to influence the mobility of the rigid parts of the polymer chain while the spacer remains almost unaffected by the degree of polymerization. The mobility of the spacer carbons depends, however, on the length of the side chains. Even a magnetic field of 7 Tesla was not able to cause a reasonable macroscopic orientation in most of the samples, probably hindered by the high viscosity of the melts.
Characterization of short glass fiber filled polystyrene by fiber orientation and mechanical properties
Authors: Lee Seok Won , Youn Jae Ryoun 
Published: March 2011

AbstractA quasi‐steady state, non‐isothermal, compressible, inelastic, and creeping flow of polymer melt into a thin cavity is analyzed to predict fiber orientation states. Modified Cross model and Tait's state equation are adopted to consider shear‐thinning behavior and compressibility of the polymer melt. Second order tensors are introduced to describe 3‐dimensional fiber orientation. Flow‐induced fiber orientation can be predicted by solving the equations of change for the orientation tensor with a suitable closure approximation. The orthotropic closure is applied except for the case of low interaction coefficient. Fiber orientation develops mainly due to shear flow in the skin layer and due to stretching effect in the core layer. It turns out that the compressibility, which induces additional velocity gradients during packing, reduces development of the fiber orientation. Results are dependent upon the magnitude of the interaction coefficient. The larger the interaction coefficient, the smaller the orientation development and the effect of compressibility. To predict orientation dependent mechanical properties, the orientation averaging for an arbitrary orientation is carried out from the properties of a transversely isotropic unit cell. The compressibility reduces the axial modulus and increases the transverse modulus. Opposite trends are observed for thermal expansion coefficients. It is also observed that the consideration of compressibility reduces the overall anisotropy of the molded product. Effects of compressibility on mechanical properties of the parts are reduced as the interaction coefficient becomes larger.
Element‐containing fibers with epoxy binders: Structures and properties of hardened compositions
Authors: Dubkova Valentina I. 
Published: March 2011

AbstractNew types of composites based on element‐containing carbon fibers (ECFs) and an epoxy binder have been developed. The results show that the presence of functional groups within the ECF structure affects significantly the reaction mechanism of the epoxy matrix. Connections between processes occuring in the interphase zone (the boundary layer) and the properties of hardened composites have been revealed. The factors controlling the binder hardening reactions occuring on surfaces of interphases when creating composites with improved physical and mechanical properties as well as with predermined service properties (polishing, anion‐exchange, anti‐corrosion, flame‐resistance, controlled range of electrical resistance etc) are defined.A potential for using ECFs in a role unusual for them, namely as hardeners for epoxide binders, has been established. Applications of reactive ECFs which may function both as a filler and as a hardener provides longer service life of the composites and minimizes the amount of volatile products released in the process of hardening.
Molecular motions in a polycarbonate composite as studied by thermally stimulated recovery and dynamic mechanical analysis
Authors: Alves Natália M. , Mano João F. , Ribelles José L. Gómez 
Published: March 2011

AbstractThe viscoelastic properties of a short carbon‐fibre reinforced polycarbonate are studied in the glassy state and in the glass transition region by means of Thermally Stimulated Recovery (TSR) and Dynamic Mechanical Analysis (DMA) techniques in the flexural mode. The temperature calibration of the apparatus is discussed. Each thermal sampling experiment is analysed according to a simple Voigt‐Kelvin model in which the temperature dependence of the retardation time follows the Arrhenius equation with two adjustable thermokinetic parameters. Non‐linear fittings of the experimental data are performed with the corresponding constitutive equation. Both the activation energy and the pre‐exponential factor follow the usual trends with temperature and present the well‐known compensation phenomena. A divergence between the TSR results of the two materials is found above ± 145°C and may be a result of the effect of the interface. The observed movements in the glassy state which are still found to have a cooperative character are analysed according to the Adam‐Gibbs theory. Dynamic‐mechanical relaxation properties of the composite are reported and analysed in terms of Takayanagi's block model.
Hodgkin lymphoma risk: Role of genetic polymorphisms and gene–gene interactions in DNA repair pathways
Authors: Monroy Claudia M. , Cortes Andrea C. , Lopez Mirtha , Rourke Elizabeth , Etzel Carol J. , Younes Anas , Strom Sara S. , El‐Zein Randa 
Published: March 2011

AbstractDNA repair variants may play a potentially important role in an individual's susceptibility to developing cancer. Numerous studies have reported the association between genetic single nucleotide polymorphisms (SNPs) in DNA repair genes and different types of hematologic cancers. However, to date, the effects of such SNPs on modulating Hodgkin lymphoma (HL) risk have not yet been investigated. We hypothesized that gene–gene interaction between candidate genes in direct reversal, nucleotide excision repair (NER), base excision repair (BER) and double strand break (DSB) pathways may contribute to susceptibility to HL. To test this hypothesis, we conducted a study on 200 HL cases and 220 controls to assess associations between HL risk and 21 functional SNPs in DNA repair genes. We evaluated potential gene–gene interactions and the association of multiple polymorphisms in a chromosome region using a multi‐analytic strategy combining logistic regression, multi‐factor dimensionality reduction and classification and regression tree approaches. We observed that, in combination, allelic variants in the XPC Ala499Val, NBN Glu185Gln, XRCC3 Thr241Me, XRCC1 Arg194Trp, and XRCC1 399Gln polymorphisms modify the risk for developing HL. Moreover, the cumulative genetic risk score revealed a significant trend where the risk for developing HL increases as the number of adverse alleles in BER and DSB genes increase. These findings suggest that DNA repair variants in BER and DSB pathways may play an important role in the development of HL. © 2011 Wiley Periodicals, Inc.
Hypodipsia discriminates progressive supranuclear palsy from other parkinsonian syndromes
Authors: Stamelou Maria , Christ Helena , Reuss Alexander , Oertel Wolfgang , Höglinger Günter 
Published: March 2011

AbstractBackground:The objective of this study was to evaluate whether the sensation of thirst differs between patients with progressive supranuclear palsy (PSP), multiple system atrophy with predominant parkinsonism (MSA‐P), and Parkinson's disease (PD).Methods:We administered a standardized thirst questionnaire to age‐, sex‐, and stage‐matched patients with probable PSP, PD, and MSA‐P and healthy controls (HC), n = 15/group. In an independent cohort (n = 10/group), we provoked thirst by infusing hypertonic NaCl in age‐, sex‐, and stage‐matched patients with PSP, PD, and MSA‐P and recorded plasma osmolality and thirst (visual analog scale).Results:On questioning, 73% of PSP patients reported a reduced sensation of thirst (hypodipsia) compared with previous years (HC, 0%; PD, 7%; MSA‐P, 7%; P < .0001). On NaCl infusion, PSP patients reported significantly lower thirst than did PD and MSA‐P patients for all times from 20 to 95 minutes (P < .05). The thirst score at 25 minutes discriminated individual PSP patients well from PD and MSA‐P patients.Conclusions:Hypodipsia appears helpful in differentiating PSP from PD and MSA‐P. © 2011 Movement Disorder Society
Fast concomitant gradient field and field inhomogeneity correction for spiral cardiac imaging
Authors: Cheng Joseph Y. , Santos Juan M. , Pauly John M. 
Published: March 2011

AbstractNon‐Cartesian imaging provides many advantages in terms of flexibility, functionality, and speed. However, a major drawback to these imaging methods is off‐resonance distortion artifacts. These artifacts manifest as blurring in spiral imaging. Common techniques that remove the off‐resonance field inhomogeneity distortion effects are not sufficient, because the high order concomitant gradient fields are nontrivial for common imaging conditions, such as imaging 5 cm off isocenter in an 1.5 T scanner. Previous correction algorithms are either slow or do not take into account the known effects of concomitant gradient fields along with the field inhomogeneities. To ease the correction, the distortion effects are modeled as a non‐stationary convolution problem. In this work, two fast and accurate postgridding algorithms are presented and analyzed. These methods account for both the concomitant field effects and the field inhomogeneities. One algorithm operates in the frequency domain and the other in the spatial domain. To take advantage of their speed and accuracy, the algorithms are applied to a real‐time cardiac study and a high‐resolution cardiac study. Both of the presented algorithms provide for a practical solution to the off‐resonance problem in spiral imaging. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Transcriptional deficits in oxidative phosphorylation with statin myopathy
Authors: Hubal Monica J. , Reich Kimberly A. , De Biase Andrea , Bilbie Cherie , Clarkson Priscilla M. , Hoffman Eric P. , Thompson Paul D. 
Published: March 2011

AbstractIntroduction: Hydroxymethylglutaryl–coenzyme A (HMG‐CoA) reductase inhibitors, or statins, are widely used drugs for hyperlipidemia and are generally well‐tolerated, but the can produce skeletal muscle toxicity. The molecular mechanisms driving statin myopathy are unknown. We investigated the effects of statin treatment and eccentric (damaging) exercise on transcriptional patterns between statin myopathy (Sym; N = 9) and statin‐tolerant subjects (Asym; N = 6). Methods: Skeletal muscle biopsies were collected 6 h post‐exercise at baseline and after statin treatment. Subjects performed concentric (non‐damaging) exercise with one leg and concentric + eccentric exercise with the other leg using a cross‐over design between time‐points. Results: Sym as compared with Asym demonstrated decreased skeletal muscle gene expression for oxidative phosphorylation–related and mitochondrial ribosomal protein genes before and after statin treatment with eccentric exercise. Conclusions: These results suggest that pre‐existing deficiencies in energy production may contribute to the development of symptoms during statin therapy, especially when muscle is exposed to eccentric exercise. Muscle Nerve 44: 393–401, 2011
Role of RNA binding protein HuR in ductal carcinoma in situ of the breast
Authors: Heinonen Mira , Hemmes Annabrita , Salmenkivi Kaisa , Abdelmohsen Kotb , Vilén Suvi‐Tuuli , Laakso Marko , Leidenius Marjut , Salo Tuula , Hautaniemi Sampsa , Gorospe Myriam , Heikkilä Päivi , Haglund Caj , Ristimäki Ari 
Published: March 2011

AbstractHuR is a ubiquitously expressed RNA‐binding protein that modulates gene expression at the post‐transcriptional level. It is predominantly nuclear, but can shuttle between the nucleus and the cytoplasm. While in the cytoplasm HuR can stabilize its target transcripts, many of which encode proteins involved in carcinogenesis. While cytoplasmic HuR expression is a marker of reduced survival in breast cancer, its role in precursor lesions of malignant diseases is unclear. To address this we explored HuR expression in atypical ductal hyperplasia (ADH) and in ductal in situ carcinomas (DCIS). We show that cytoplasmic HuR expression is elevated in both ADH and DCIS when compared to normal controls, and that this expression associated with high grade, progesterone receptor negativity and microinvasion and/or tumour‐positive sentinel nodes of the DCIS. To study the mechanisms of HuR in breast carcinogenesis, HuR expression was silenced in an immortalized breast epithelial cell line (184B5Me), which led to reduction in anchorage‐independent growth, increased programmed cell death and inhibition of invasion. In addition, we identified two novel target transcripts (CTGF and RAB31) that are regulated by HuR and that bind HuR protein in this cell line. Our results show that HuR is aberrantly expressed at early stages of breast carcinogenesis and that its inhibition can lead to suppression of this process. ArrayExpress Accession No. E‐MEXP‐3035. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Effect of processing procedures and conditions on structural, morphological, and rheological properties of polyethylene/polyamide/nanoclay blends
Authors: Médéric Pascal , Ville Julien , Huitric Jacques , Moan Michel , Aubry Thierry 
Published: March 2011

AbstractThe article deals with the effect of processing procedures and conditions on structural, morphological, and rheological properties of ternary blends composed of polyethylene (PE), polyamide (PA)‐12, and organically modified montmorillonite nanoclay with selective affinity. Samples were prepared from PE/PA and PA/PE blends, either by simultaneous mixing or from a polymer/clay masterbatch, using two processing conditions. The results have shown the existence of a weight fraction threshold, above which no significant processing effect was observed. Below this weight fraction threshold, the results tend to underline the significant role of two parameters that depend on processing procedures and/or conditions: the contact time between PE and PA phases and the contact time between clay and PA. Clay structure, blend morphology, and rheological properties were all shown to depend on these two parameters, and also on the nature of the matrix (PE or PA), because of the selective affinity of clay toward polymer phases. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Melting and crystallization behavior of copolymer from cyclic butylene terephthalate and polycaprolactone
Authors: Wu Chang‐Mou , Huang Cheng‐Wei 
Published: March 2011

AbstractIn this study, we investigated the nonisothermal crystallization kinetics, crystallization morphology, and melting behavior of polymerized cyclic butylene terephthalate (pCBT) copolymerized with polycaprolactone (PCL). The results of this experiment indicated that the Ozawa exponent varied between 2 and 3 for pCBT, but between 1 and 2 for blends of pCBT/PCL. At the same temperature (185°C), the crystallization rate constant KT for pCBT/PCL blend was much lower than for pCBT homopolymer. These results indicated a strong hindrance on the crystallization of pCBT/PCL blends. The pCBT and pCBT/PCL samples exhibited no visible difference in morphology or microstructure. However, the crystallization and melting peak temperature of pCBT/PCL blends was ∼20°C lower than that of pCBT homopolymer. Crystal morphology confirmed that the mechanism of simultaneous polymerization and crystallization found applicable to pCBT homopolymer did not apply for blends of pCBT/PCL. It therefore appears that crystallization should be delayed until after the completion of pCBT/PCL copolymerization. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Electrospinning of poly(hydroxybutyrate‐co‐hydroxyvalerate) fibrous tissue engineering scaffolds in two different electric fields
Authors: Tong Ho‐Wang , Wang Min 
Published: March 2011

AbstractPoly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) was electrospun into ultrafine fibrous nonwoven mats. Different from the conventional electrospinning process, which involves a positively charged conductive needle and a grounded fiber collector (i.e., positive voltage (PV) electrospinning), pseudo‐negative voltage (NV) electrospinning, which adopted a setup such that the needle was grounded and the fiber collector was positively charged, was investigated for making ultrafine PHBV fibers. For pseudo‐NV electrospinning, the effects of various electrospinning parameters on fiber morphology and diameter were assessed systematically. The average diameters of PHBV fibers electrospun via pseudo‐NVs were compared with those of PHBV fibers electrospun via PVs. With either PV electrospinning or pseudo‐NV electrospinning, the average diameters of electrospun fibers ranged between 500 nm and 4 μm, and they could be controlled by varying the electrospinning parameters. The scientific significance and technological implication of fiber formation by PV electrospinning and pseudo‐NV electrospinning in the field of tissue engineering were discussed. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Structure–reactivity relationship for alcohol oxidations via hydride transfer to a carbocationic oxidizing agent
Authors: Lu Yun , Bradshaw Joshua , Zhao Yu , Kuester William , Kabotso Daniel 
Published: March 2011

AbstractSecond‐order rate constants were determined for the oxidation of 27 alcohols (R1R2CHOH) by a carbocationic oxidizing agent, 9‐phenylxanthylium ion, in acetontrile at 60 °C. Alcohols include open‐chain alkyl, cycloalkyl, and unsaturated alcohols. Kinetic isotope effects for the reaction of 1‐phenylethanol were determined at three H/D positions of the alcohol (KIEα‐D = 3.9, KIEβ‐D3 = 1.03, KIEOD = 1.10). These KIE results are consistent with those we previously reported for the 2‐propanol reaction, suggesting that these reactions follow a hydride‐proton sequential transfer mechanism that involves a rate‐limiting formation of the α‐hydroxy carbocation intermediate. Structure–reactivity relationship for alcohol oxidations was deeply discussed on the basis of the observed structural effects on the formation of the carbocationic transition state (Cδ+OH). Efficiencies of alcohol oxidations are largely dependent upon the alcohol structures. Steric hindrance effect and ring strain relief effect win over the electronic effect in determining the rates of the oxidations of open‐chain alkyl and cycloalkyl alcohols. Unhindered secondary alkyl alcohols would be selectively oxidized in the presence of primary and hindered secondary alkyl alcohols. Strained C7C11 cycloalkyl alcohols react faster than cyclohexyl alcohol, whereas the strained C5 and C12 alcohols react slower. Aromatic alcohols would be efficiently and selectively oxidized in the presence of aliphatic alcohols of comparable steric requirements. This structure–reactivity relationship for alcohol oxidations via hydride‐transfer mechanism is hoped to provide a useful guidance for the selective oxidation of certain alcohol functional groups in organic synthesis. Copyright © 2011 John Wiley & Sons, Ltd.
Substituent effects on the pH‐dependent multiequilibria of flavylium salt analogs of anthocyanins
Authors: Freitas Adilson A. , Dias Luis G. , Maçanita António A.L. , Quina Frank H. 
Published: March 2011

AbstractSubstituent effects on the hydration, tautomerization, and isomerization equilibria of flavylium salts can be described by a series of linear free energy relationships (LSER) based on Hammett correlations. The positions on the flavylium rings were classified as either activated (para‐like) or nonactivated (meta‐like) to decide which σ value to employ (σR or σm, respectively), while the steric effects of substituents at C‐3 were included via the ES parameter. Based on these relationships, we then show that it is possible to predict values of the “apparent pKa” (pKap) of flavylium ions that were not included in the original data set, as well as those of several naturally occurring anthocyanins. The value of pKap provides a measure of the thermodynamic stability of the flavylium cation as a function of pH and is directly related to the pH range in which the color of the flavylium cation form of anthocyanins persists in aqueous solution. Copyright © 2011 John Wiley & Sons, Ltd.