bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology Evolution During Polymer Crystallization Simultaneous Calorimetric and Optical Measurements
Authors: De Santis Felice , Vietri Anna Rosa , Pantani Roberto 
Published: March 2006

AbstractThe crystallization of the isotactic poly(propylene) (I‐PP) has been studied carrying out measurements by means of a special calorimeter connected to a microscope and a digital acquisition system of images. To authors' knowledge, this is the first time that simultaneous calorimetric and optical measurements are carried out on polymers. The analysis of Polarized Optical Microscopy images has allowed the appraisal of nucleation density and growth rate in isothermal and non isothermal conditions. The results obtained in isothermal conditions have been analyzed through the Kolmogoroff model and the crystallinity calculated from the model has been compared with that obtained from the calorimetric measurements.
Nano‐composite Fibers Based on Poly(p‐benzamide)‐Montmorillonite
Authors: Marsano Enrico , Azzurri Francesco , Corsini Paola 
Published: March 2006

AbstractNano‐composites fibers made of poly(p‐benzamide) (PBA), a rigid liquid crystalline polymer, and an inorganic nano‐filler, montmorrilonite (MMT), were prepared by a wet spin process. Dimethylacetamide‐3% (w/w) LiCl was used as a solvent. Polymer concentration, Cp = 6.5% (w/w), was maintained as high as possible, but lower than the critical concentration for the appearance of a liquid crystalline phase, Cp′ = 6.7%. MMT dispersed in PBA solution was 2.6–5.0% (w/w) with respect to PBA. The Polymer‐MMT solutions show a liquid crystalline phase at polymeric concentration above 6.7% and they show by a high metastability and a slow phase separation. The PBA‐MMT solutions show good spinnability and fibers are characterized by a significant increasing in modulus and breaking strength. WAXD and TEM analyses suggest that partially intercalated PBA/MMT nano‐composite fibers have been obtained.
Optically Active Methacrylic Polymers Bearing in the Side Chain the (S)‐3‐Hydroxypyrrolidinyl Group Linked totrans‐bisazoaromatic Chromophore: Synthesis and Characterization
Authors: Angiolini Luigi , Benelli Tiziana , Giorgini Loris , Mauriello Francesco , Salatelli Elisabetta 
Published: March 2006

AbstractThe synthesis by radical homopolymerization of a novel optically active methacrylic polymer containing a side‐chain chiral moiety linked to a photochromic bisazoaromatic chromophore has been carried out starting from the related monomer (S)‐3‐methacryloyloxy‐1‐[4′‐phenylazo‐(4‐azobenzene)]‐pyrrolidine [(S)‐MPAAP]. The polymeric derivate has been fully characterized and its spectroscopic properties compared to those of the monomer and of the corresponding homopolymer bearing only one azoaromatic chromophore in the side chain. The optical activity displayed by the bisazo polymer is discussed in terms of extent of chiral conformation assumed by the macromolecules as a consequence of dipole‐dipole interactions between the bisazoaromatic chromophores.
Synthesis of Polymers Containing Second Order NLO‐Active Thiophene and Thiazole Based Chromophores
Authors: Caruso Ugo , Diana Rosita , Fort Alain , Panunzi Barbara , Roviello Antonio 
Published: March 2006

AbstractGrounding on the evidence that thiophene or thiazole rings in donor‐acceptor chromophoric systems promote enhancement of charge transfer and nonlinear optical responses, in this work NLO properties have been investigated of organic polymers containing azoic chromophores based on dinitrothiophene or nitrothiazole moieties. It has been carried out the azo coupling reaction directly between a series of copolymers and diazonium salts containing the etherocyclic group at different grafting percentages.
Thermal Expansion Coefficients of the Axes of the Unit Cell of Syndiotactic 1,2‐Poly(1,3‐Butadiene)
Authors: Napolitano Roberto , Pirozzi Beniamino , Esposito Simona 
Published: March 2006

AbstractSamples of syndiotactic 1,2‐poly(1,3‐butadiene) subjected to different thermal and mechanical treatments have been characterized by DSC and X‐ray. The treatments induce changes in the crystallinity, crystal size and size of the unit cell, but do not evidence polymorphism. Values of the thermal expansion coefficients of the axes of the unit cell have been determined by X‐ray measurements at various temperatures.
iPP Based Nanocomposites Filled with Calcium Carbonate Nanoparticles: Structure/Properties Relationships
Authors: Avella Maurizio , Cosco Simona , Lorenzo Maria Laura Di , Pace Emilia Di , Errico Maria Emanuela , Gentile Gennaro 
Published: March 2006

AbstractIsotactic polypropylene (iPP) based nanocomposites filled with calcium carbonate nanoparticles (CaCO3) were prepared by melt mixing and structure‐properties relationships of the nanomaterials were studied. Elongated CaCO3 nanopowders coated with two different coating agents, polypropylene‐maleic anhydride graft copolymer (iPP‐g‐MA) and fatty acids (FA), were tested as nanoreinforced phases. The influence of surface treatment of the nanoparticles on the polymer/nanofillers interfacial adhesion and on the final materials properties was investigated. Morphological analysis showed that the selected coating agents induce different iPP/nanofiller adhesion degrees. Young's modulus increases as a function of the nanoparticles content and the coating agent nature. Finally, all the prepared nanocomposites showed a significant improvement of iPP barrier properties either to oxygen or to carbon dioxide.
The Crystallization and Melting Processes of Poly(L‐lactic acid)
Authors: Di Lorenzo Maria Laura 
Published: March 2006

AbstractA throughout investigation of crystallization and melting behavior of poly(L‐lactic acid) is detailed in this contribution. Crystallization analyses, conducted in both isothermal and non‐isothermal conditions, revealed the occurrence of a sudden acceleration in phase transition rate in the temperature range between 100 and 118 °C. This unusual increase, due to very high rates of spherulite growth, seems not related to morphological changes of PLLA spherulites, nor to unexpected variations in nucleation rate. DSC analyses disclosed multiple melting behavior of PLLA, depending on crystallization temperature. At low temperatures the very high crystallization rates lead to the achievement of low values of crystalline degree, with formation of small and/or defective crystals, which have a large tendency to reorganize into more stable structures during the heating scan that leads to complete fusion. The multiple melting process of PLLA was also analyzed at different heating rates.
Predictors of weight loss in Parkinson's disease
Authors: Uc Ergun Y. , Struck Lynn K. , Rodnitzky Robert L. , Zimmerman Bridget , Dobson Judith , Evans William J. 
Published: March 2006

AbstractThe objective of this study was to examine the change of body weight (BW) among Parkinson's disease (PD) patients and controls over years and determine the predictors of weight loss among PD patients. Studies on weight loss in PD studies are cross‐sectional, have a short follow‐up, or lack in clinical detail. We examined the percentage of BW change over years among 49 PD patients and 78 controls. The controls were from another study on longitudinal evolution of BW and body composition in the elderly. We determined the BW, Hoehn and Yahr (HY) stage, and dyskinesia status of 49 consecutive nondemented PD patients with symptom duration of 6.1 ± 0.7 years (mean ± SEM) and ascertained their BW at the time of diagnosis and 2.4 ± 0.2 years before the diagnosis from medical records. We collected data again 7.2 ± 0.5 years after the first visit. The PD group lost 7.7% ± 1.5% of BW over the entire symptomatic period (13.1 ± 0.8 years), while the control group lost only 0.2% ± 0.7% of BW over 9.9 ± 0.1 years; weight loss was clinically significant (>5%) in 55.6% of PD patients vs. 20.5% of the controls (both P values < 0.001, adjusted for sex, baseline age, and observation period duration). PD patients lost weight in both the early and advanced phases. While worsening of parkinsonism was the most important factor, age at diagnosis, emergence of visual hallucinations, and possibly dementia were also associated with weight loss. We demonstrated significant weight loss in PD patients compared to controls over approximately 1 decade. Neurodegeneration involving both motor and nonmotor systems may be associated with weight loss in PD. © 2006 Movement Disorder Society
New global a priori estimates for the third‐grade fluid equations
Authors: Steinhauer Mark , Urbano José Miguel , Videman Juha 
Published: March 2006

AbstractThis note bridges the gap between the existence and regularity classes for the third‐grade Rivlin–Ericksen fluid equations. We obtain a new global a priori estimate, which conveys the precise regularity conditions that lead to the existence of a global in time regular solution. Copyright © 2006 John Wiley & Sons, Ltd.
The differential role of prostaglandin E2 receptors EP3 and EP4 in regulation of fever
Authors: Lazarus Michael 
Published: March 2006

AbstractThe innate immune system of mammals is able to detect bacteria when they infect local tissue or enter the blood stream, and initiate an immediate immune response. Prostaglandin (PG) E2 is considered as the most important link between the peripheral immune system and the brain. Due to four PGE2 receptors (EP receptors) and their differential expression in various areas of the hypothalamus and brain stem, PGE2 mediates different components of the acute phase reaction. A fever model is discussed in which the preoptic area contains the mechanisms for both hyperthermic and hypothermic responses and EP receptors in the median preoptic area (MnPO) modulate the thermogenic system. The neuron‐specific modulation of EP receptors in the MnPO can be critically tested by using Cre‐recombinase‐mediated DNA recombination in genetically engineered mice. A concept for mice with conditional expression of EP3R and EP4R to investigate the different roles of those receptors in lipopolysaccharide (LPS)‐induced fever is presented.
Estrogens modulate the gene expression of Wnt‐7a in cultured endometrial adenocarcinoma cells
Authors: Wagner Jörg , Lehmann Leane 
Published: March 2006

AbstractThe glycoprotein Wnt‐7a participates in a signaling pathway that transmits information among uterine cell types. Disruption of this pathway by the transplacentally acting carcinogen diethylstilbestrol (DES) is associated with morphological abnormalities of the female reproductive tract (FRT). This raises the question whether estrogens in the diet might also interfere with this pathway. Therefore, this study investigated the influence of the steroid hormone 17β‐estradiol (E2), the mycotoxin zearalenone (ZEN), the soy phytoestrogen genistein (GEN), and DES on the expression of Wnt‐7a in an endometrial adenocarcinoma cell line (Ishikawa cells) by reverse transcription/competitive PCR. In addition, the enzymatic activity of alkaline phosphatase (ALP) was determined, which is estrogen receptor (ER)‐dependently regulated in Ishikawa cells. After treatment of Ishikawa cells with E2, ZEN, GEN, and DES, a decrease in the gene expression of Wnt‐7a was observed. Maximum effect (50% reduction) was observed after treatment with concentrations that induced maximum expression of the ALP. Experiments in the presence of the ER antagonist (ICI 182,780) suggested that the ER is involved in the regulation of Wnt‐7a in Ishikawa cells. In conclusion, interference with the expression of Wnt genes in the FRT might be a novel mechanism by which estrogens disrupt the function of the FRT.
Stage‐dependent Dishevelled‐1 expression during mouse spermatogenesis suggests a role in regulating spermatid morphological changes
Authors: Ma Pengpeng , Wang Huizhen , Guo Rui , Ma Quanhong , Yu Zuoren , Jiang Yi , Ge Yehua , Ma Jing , Xue Shepu , Han Daishu 
Published: March 2006

AbstractDishevelled (Dsh in Drosophila or DVL in mice) is a member of the highly conserved Wg/Wnt signaling pathway, which regulates important processes such as cell proliferation, polarity, and specification of cell fate. Three orthologous genes of Dishevelled (Dvl‐1, Dvl‐2, and Dvl‐3) have been found in both humans and mice. They play pivotal roles in regulating cell morphology and a variety of changes in cell behaviors. In the present study, we show that the expression of Dvl‐1 is stage‐dependent during mouse spermatogenesis, although Dvl‐2 and Dvl‐3 show relative consistent expression. The expression of Dvl‐1 mRNA first appears in pachytene spermatocytes, increases in round and elongating spermatids, and then turns to an undetectable level in mature sperm cells. Analyses of immunohistochemistry and immunofluorescence staining show that DVL‐1 is present diffusely in the cytoplasm of pachytene spermatocytes and exhibits mainly a vesicular pattern and perinuclear distribution and a weak diffusely cytoplasmic signal in round and elongating spermatids. The vesicular pattern of DVL‐1 has been observed by previous studies in somatic cells, and suggested to play roles in signal transduction. Immunoprecipitation experiments show that DVL‐1 coimmunprecipitates with spermatogenic cells β‐actin rather than α‐tubulin. These results indicate that DVL‐1 may be involved in spermatid morphological changes during mouse spermiogenesis through mediating signal transduction and/or regulating actin cytoskeleton organization. Mol. Reprod. Dev. © 2006 Wiley‐Liss, Inc.
Priority and dynamic scheduling in a make‐to‐stock queue with hyperexponential demand
Authors: Jain Apurva 
Published: March 2006

AbstractWe consider the scheduling problem in a make‐to‐stock queue with two demand classes that can be differentiated based on their variability. One class experiences Poisson arrivals and the other class experiences hyperexponential renewal arrivals. We provide an exact analysis of the case where the demand class with higher variability is given non‐preemptive priority. The results are then used to compare the inventory cost performance of three scheduling disciplines, first‐come first‐serve and priority to either class. We then build on an existing dynamic scheduling heuristic to propose a modification that works well for our system. Extensions of the heuristic to more than two classes and to the case where demand state is known are also discussed. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006.
Treatment of unresectable malignant rhabdoid tumor of the orbit with tandem high‐dose chemotherapy and gamma‐knife radiosurgery
Authors: Watanabe Hiroyoshi , Watanabe Tsutomu , Kaneko Michiya , Suzuya Hiroko , Onishi Toshihiro , Okamoto Yasuhiro , Miyake Hajime , Yasuo Kensaku , Hirose Takanori , Kagami Shoji 
Published: March 2006

AbstractMalignant rhabdoid tumor (MRT) is a rare and highly aggressive tumor that primarily occurs in very young children. We report here a patient with a primary MRT of the orbit who received tandem high‐dose chemotherapy and gamma‐knife radiosurgery. Although the tumor was not completely removed, and the initial chemotherapy failed, the patient achieved long‐term survival after this modality of treatment. This approach may be one to be further considered in patients with MRT. Pediatric Blood Cancer 2006;47:846–850. © 2006 Wiley‐Liss, Inc.
Clinical appearance of neuroblastoma 10 years after screening
Authors: Kerbl Reinhold , Urban Christian E. , Zotter Heinz , Lackner Herwig , Sovinz Petra , Ambros Peter F. 
Published: March 2006

AbstractA follow‐up study was performed for children with previous repeated positive results by neuroblastoma mass screening and negative clinical results (30 out of 439,128 children screened in Austria between 1991 and 2003, median follow‐up 113 months). Four children had continuously elevated urine catecholamines for more than 6 months. One of these patients was diagnosed with pelvic neuroblastoma and multiple metastases 10 years after the first positive screening result. In the light of a ‘wait and see’ strategy for localized neuroblastomas, our observation suggests that these patients should be further observed even after normalization of urine catecholamines. Pediatr Blood Cancer 2007;49:1012–1014. © 2006 Wiley‐Liss, Inc.
Synthesis and characterization of polyurethane/montmorillonite nanocomposites by in situ polymerization
Authors: Ding Qingjun , Liu Baolei , Zhang Qiang , He Qihui , Hu Baixing , Shen Jian 
Published: March 2006

AbstractIn this paper, a new type of organophilic montmorillonite, co‐treated with cetyltrimethyl ammonium bromide (CTAB) and 4,4′‐diphenymethylate diisocyanate (MDI), was modified and applied to prepare polyurethane/montmorillonite nanocomposites via in situ polymerization. The nanoscale montmorillonite layers were exfoliated and dispersed relatively homogeneously in the polyurethane matrix, and characterized by X‐ray diffraction and transmission electron microscopy. The thermal degradation temperature of the nanocomposites increased, as compared with pristine polyurethane. Dynamic mechanical analysis confirmed the constraining effect of exfoliated montmorillonite layers on polyurethane chains, which benefited the increased storage modulus and increased glass transition temperature. Tensile tests showed that the exfoliated nanocomposites were reinforced and toughened by the addition of nanometer‐size montmorillonite layers. Copyright © 2006 Society of Chemical Industry
Dehydration of ethanol/water mixtures by pervaporation using soluble polyimide membranes
Authors: Li Chi‐Lan , Lee Kueir‐Rarn 
Published: March 2006

AbstractA series of soluble polyimides derived from 3,3′,4,4′‐benzhydrol tetracarboxylic dianhydride (BHTDA) with various diamines such as 1,4‐bis(4‐aminophenoxy)‐2‐tert‐butylbenzene (BATB), 1,4‐bis(4‐aminophenoxy)‐2,5‐di‐tert‐butylbenzene (BADTB), and 2,2′‐dimethyl‐4,4′‐ bis(4‐aminophenoxy)biphenyl (DBAPB) were investigated for pervaporation separation of ethanol/water mixtures. Diamine structure effect on the pervaporation of 90 wt% aqueous ethanol solution through the BHTDA‐based polyimide membranes was studied. The separation factor ranked in the following order: BHTDA–DBAPB > BHTDA–BATB > BHTDA–BADTB. The increase in molecular volume for the substituted group in the polymer backbone increased the permeation rate. As the feed ethanol concentration increased, the permeation rate increased, while the water concentration in the permeate decreased for all polyimide membranes. The optimum pervaporation performance was obtained by the BHTDA–DBAPB membrane with a 90 wt% aqueous ethanol solution, giving a separation factor of 141, permeation rate of 255 g m−2 h−1 and 36 000 pervaporation separation index (PSI) value. Copyright © 2006 Society of Chemical Industry
Structural effects of type of intercalant in poly (4‐vinylpyridine) nanocomposites: compatible homopolymer or block copolymer
Authors: Şen Sinan , Nugay Nihan , Nugay Turgut 
Published: March 2006

Abstract4‐vinylpyridine monomer was mixed with organophilic montmorillonite (MMT) clay and polymerized in the presence of free‐radical initiator. MMT clay was rendered organophilic by means of ion‐exchanging sodium cations for low‐molecular‐weight quaternized poly(4‐vinylpyridine) (P4VP) homopolymer and diblock copolymers of styrene and quaternized 4‐vinylpyridine (SVP) with different sequence lengths. The swelling behaviour of the MMT clay was studied by X‐ray diffraction (XRD). After the cation exchange, the resulting organophilic clays showed an expansion of interlayer distance indicating the nanoscale ordering of intercalant polymer and MMT layers. The nanocomposite materials, when moulded, exhibited improved thermal stability and dynamic mechanical properties compared with neat P4VP. The composite, having longer ionic segments in its organophilic MMT, showed exfoliated nanocomposite structure as well as higher stiffness and damping properties at higher temperatures even for MMT loading as low as 2 wt%. Copyright © 2006 Society of Chemical Industry
A photo‐dependent capacitance model of GaAs MESFET's
Authors: Narasimha Murty Neti V. L. , Jit S. 
Published: March 2006

AbstractA new and simple analytical model for determining the photo‐effects on the gate–source and gate–drain capacitances of GaAs MESFET's has been presented for both the linear and saturation regions. A new model for the photovoltage developed across the Schottky junction due to the illumination has been used to investigate the photo‐dependent characteristics of the above capacitances. It has been observed that the gate–source and gate–drain capacitances are increased with the increase in the incident illumination level to the device in its linear region of operation whereas in the saturation region, the gate–source capacitance is increased but the gate–drain capacitance is observed to be decreased with the increase in the incident optical intensity level. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study of improved two‐dimensional electron gas density in AlGaN/GaN/AlGaN double heterostructure
Authors: Kong Y. C. , Chu R. M. , Zheng Y. D. , Zhou C. H. , Shen B. , Gu S. L. , Zhang R. , Han P. , Shi Y. , Jiang R. L. 
Published: March 2006

AbstractWe evaluate the Alx Ga1–x N/GaN/Aly Ga1–y N double heterostructure (DH) for heterostructure field‐effect transistor applications, where the GaN quantum well is compressively strained on a relaxed crack‐free Aly Ga1–y N buffer layer, so that the Al content in the Alx Ga1–x N top barrier can be improved as compared with a conventional Alx Ga1–x N/GaN single heterostructure (SH) with the same strain in the Alx Ga1–x N layer. By self‐consistently solving the coupled Schrödinger and Poisson equations, we find that the two‐dimensional electron gas (2DEG) sheet density in an Al0.6Ga0.4N/GaN/Al0.3Ga0.7N DH is 2.59 × 1013 cm–2, much higher than the 1.71 × 1013 cm–2 in a conventional Al0.3Ga0.7N/GaN SH. The 2DEG sheet density increases with increasing Al content x and decreases slightly with increasing y . With a fixed Al content (x – y ) ratio, y is the key parameter determining the 2DEG density. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thickness dependent morphology and resistivity of ultra‐thin Al films grown on Si(111) by molecular beam epitaxy
Authors: Aswal D. K. , Joshi N. , Debnath A. K. , Gupta S. K. , Vuillaume D. , Yakhmi J. V. 
Published: March 2006

AbstractThe morphology and electrical resistivity of ultrathin Al metal films grown on (111) Si substrates using molecular‐beam epitaxy have been investigated. For thickness <60 nm, the film morphology consists of a two‐dimensional network of Al islands, which grows via Volmer–Weber mechanism. The coalescence of islands is found to begin at a thickness of 60 nm. The room‐temperature value of resistivity, contrary to the theoretical predictions of existing models, is found to increase monotonically with thickness. Also the temperature dependence of these films exhibited a metal‐to‐insulator transition at 110 K. The anomalous temperature dependences of resistivity have been explained using a two‐dimensional variable range hopping conduction (2d‐VRH) mechanism. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mesoscopic transport in carbon nanotubes: novel features
Authors: Latil S. , Roche S. , Triozon F. , Jiang J. , Saito R. 
Published: March 2006

AbstractWe report on novel mesoscopic transport features in carbon nanotubes. First, giant fluctuations of magnetotransport fingerprints are analyzed in boron‐doped carbon nanotubes. Depending on the energy of charge carries and applied magnetic field transport regime can be tuned from ballistic‐like to strongly diffusive, with a superimposed unbalanced contribution of quantum interference effects. Second the role of electron–phonon dephasing on conductance scaling is studied. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)