bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinicopathologic study of glioblastoma in children with neurofibromatosis type 1
Authors: Huttner Anita J. , Kieran Mark W. , Yao Xiaopan , Cruz Lilliam , Ladner Jesse , Quayle Katherine , Goumnerova Liliana C. , Irons Mira B. , Ullrich Nicole J.
Published: March 2010

Background

Neurofibromatosis type 1 (NF1) is characterized by low‐grade tumors of the central and peripheral nervous system. There is also an increased risk of developing malignant tumors. Glioblastoma is an uncommon, malignant tumor of children that is even less frequently observed in children with NF1.

Procedure

We performed a retrospective review of patients with NF1 and glioblastoma to determine specific clinical and pathologic indicators of overall prognosis.

Results

Five patients were identified from the CHB/DFCI database for whom pathologic and imaging studies were available. All pathologic specimens demonstrated vascular proliferation and necrosis. All samples stained positively for p53. Chromogenic in situ hybridization (CISH) for epidermal growth factor receptor (EGFR) copy numbers was increased, PTEN copy numbers were normal and the promoter of the O(6)‐methylguanine‐DNA methyltransferase (MGMT) gene was unmethylated in the one patient evaluated. In the same time period, there were 56 patients without NF1 diagnosed with glioblastoma who were treated at our institution. Although the small sample size precludes formal statistical analysis, the 2‐year survival of patients with NF1 is 60% with median overall survival of 9.25 years compared to non‐NF1 patients with a 2‐year survival of 25% and median overall survival 1.08 years.

Conclusions

This study provides preliminary evidence that children with NF1 may be at risk for glioblastoma, but that these patients have an increased survival compared to children without NF1. Additional molecular studies will be required to determine if the pathogenesis of these tumors differs from glioblastoma in children without NF1. Pediatr Blood Cancer 2010;54:890–896 © 2010 Wiley‐Liss, Inc.
MTRpolymorphic variant A2756G and retinoblastoma risk in Brazilian children
Authors: de Lima Elker Lene Santos , da Silva Vanessa Cavalcante , da Silva Hildson Dornelas Angelo , Bezerra Alexandre Medeiros , de Morais Vera Lucia Lins , de Morais Adriana Lins , Cruz Raquel Vera , Barros Mário Henrique Magalhães , Hassan Rocio , de Freitas Antonio Carlos , Muniz Maria Tereza Cartaxo
Published: March 2010

Background

Polymorphisms in the genes of folate and methionine metabolism enzymes have been associated with some forms of cancer by affecting DNA synthesis, repair, and methylation.

Procedure

A case–control study of 72 retinoblastoma cases and 98 cancer‐free children controls was performed to investigate whether the polymorphisms of the methylenetetrahydrofolate reductase (MTHFRC677T and A1298C), methionine synthase (MTRA2756G), carrier of reduced folate 1 (RFC‐1 A80G) and thymidylate synthase (TYMS2R > 3R) altered the risk for retinoblastoma.

Results

MTRA2756G AG plus GG genotype frequencies were higher in patients than in controls (45% vs. 26%,P = 0.03). Individual carriers of the variant allele G had a 2.02 (95% CI: 1.05–3.92)‐fold increased risk for retinoblastoma. In contrast, no association was observed with respect toMTHFRC677T and A1298C,RFCA80G, andTYMSpolymorphisms.

Conclusions

This study presents evidence for an association between theMTRA2756G polymorphism and retinoblastoma susceptibility in a Northeast population from Brazil. Pediatr Blood Cancer 2010;54:904–908 © 2010 Wiley‐Liss, Inc.
Simulations of instability in fiber spinning of polymers
Authors: Gagov Atanas , Leonov Arkady I.
Published: March 2010

This work determines the critical regimes beyond which the melt fiber spinning for noncrystallizable polymeric liquids becomes unstable. The critical draw ratio of the process is established using linear stability analysis for both isothermal and nonisothermal fiber spinning regimes. In addition, nonlinear isothermal analysis describes the complete range of the stable and unstable conditions for fiber spinning. Unlike previous studies, this research uses quite realistic viscoelastic constitutive equations extensively tested for five polymer liquids, which provides a good comparison of our calculations with available experimental data. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Effect of sparse long‐chain branching on the step‐strain behavior of a series of well‐defined polyethylenes
Authors: McGrady Christopher D. , Seay Christopher W. , Mazahir Syed M. , Baird Donald G.
Published: March 2010

The effect of sparse long chain branching, LCB, on the shear step‐strain relaxation modulus is analyzed using a series of eight high‐density polyethylene (HDPE) resins. Strains of 1 to 1250% are imposed on materials with LCB content ranging from zero to 3.33 LCB per 10,000 carbon atoms. All materials are observed to obey time–strain separation beyond some characteristic time, τk. The presence of LCB is observed to increase the value of τk relative to the linear resin. The behavior of the relaxation modulus at times shorter than τk is investigated by an analysis of the enhancement seen in the linear relaxation modulus, G0(t), as a function of strain and LCB content. This enhancement is seen to (1) increase with increasing strain in all resins, (2) be significantly larger in the sparsely branched HDPE resins relative to the linear HDPE resin, and (3) increase in magnitude with increasing LCB content. The shape and smoothness of the damping function is also investigated. The finite rise time to impose the desired strain is compared to the Rouse relaxation time of linear HDPE resins studied. Sparse LCB is found to increase the magnitude of the relaxation modulus at short times relative to the linear resin. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Synthesis of acrylamide/acrylic acid‐based aluminum flocculant for dye reduction and textile wastewater treatment
Authors: Noppakundilograt Supaporn , Nanakorn Praon , Jinsart Wanida , Kiatkamjornwong Suda
Published: March 2010

Aluminum hydroxide‐poly[acrylamide‐co‐(acrylic acid)], AHAMAA, was synthesized with a redox initiator by solution polymerization in which the effects of reactant contents were optimized. The effects of pH, temperature, and initial dye concentration on Congo red reduction were investigated. A mixture of Congo red and direct blue 71, and the composite textile dye wastewater were investigated. Adsorptions of both dyes were more effective in the nonbuffered solution than those in the buffered solution, and Congo red adsorbed more than direct blue 71 at all pHs. The adsorption of Congo red increased with increasing temperature and its initial concentration. Both dyes obeyed the Freundlich adsorption isotherm. The maximum adsorptions in 100 mg dm−3 solution were 109 ± 0.5 mg g−1 and 62 ± 6.6 mg g−1 for Congo red and direct blue 71, respectively. At 150 mg dm−3 of the mixed Congo red and direct blue 71, the adsorption was 142 ± 2 mg g−1 by 643 ± 3 mg dm−3 AHAMAA. The 40 mg g−1 dyes of the textile effluent wastewater were adsorbed by 500 mg dm−3 AHAMAA. AHAMAA could decrease turbidity of the composite wastewater containing a mixture of reactive and direct dyes from 405 to 23 NTU. POLYM. ENG. SCI., 50:1535–1546, 2010. © 2010 Society of Plastics Engineers
Beyond Frontiers of Traditional Project Management: An Approach to Evolutionary, Self-Organizational Principles and the Complexity Theory—Results of the Research Program
Authors: Saynisch Manfred
Published: March 2010

This article speculates beyond current thinking in project management, asserting that traditional project management cannot fulfill the challenges and requirements for mastering increased complexity in society, economics, and technology. The new paradigmatic evolutionary-systemic and cybernetic-systemic research results (including self-organization or chaotic systems) in the more recent natural and social sciences were analyzed based on their relevance for a new perspective in project management. Selected results of the research program will be presented, including a short description of “Project Management Second Order (PM-2)” as a highlighted result and a new paradigm in project management.
Managing Global Projects: A Structured Approach for Better Performance
Authors: Anantatmula Vittal , Thomas Michael
Published: March 2010

The purpose of this research effort is to develop a model for improving the performance of global projects using the underlying relations among the important enablers and barriers of global project performance. A number of factors are identified in the study, using a literature review to develop the model. A survey was used to determine the impact of these factors on global project performance. The model suggests different management practices for global projects versus traditional, co-located projects. Different from the outcomes of traditional projects, research results suggest that leadership and establishing trust is a first step in the initial stages of the global project.
Polymerization of 1,3‐dienes and styrene catalyzed by cationic allyl Ni(II) complexes
Authors: O'Connor Abby R. , Brookhart Maurice
Published: March 2010

Polymerizations of 1,3‐dienes using in situ generated catalyst [(2‐methallyl)Ni][B(ArF)4], 6, (ArF = 3,5‐bis(trifluoromethyl)phenyl) as well as [(2‐methallyl)Ni(mes)][B(ArF)4], 14, (mes = mesitylene) are reported. Highly sensitive complex 6 polymerizes butadiene (BD) at –30 °C to yield polybutadiene with a Mn of ca. 10 K and 94% cis‐1,4‐enchainment while less reactive isoprene (IP) was polymerized at 23 °C to yield polyisoprene with Mn ca. 7 K. Complex 6 was also shown to polymerize a functionalized diene, 2,3‐bis(4‐trifluoroethoxy‐4‐oxobutyl)‐1,3‐BD, to polymer with Mn = 113 K. The stable and readily isolated arene complex 14 initiates BD and IP polymerizations at somewhat higher temperatures relative to 6 and delivers polymers with higher molecular weights. Complex [(allyl)Ni(mes)][B(ArF)4], 13, catalyzes polymerization of styrene to yield polystyrene with high conversion, Mn's = ca. 6 K and MWD = 2. The π‐benzyl complex [(η3‐1‐methylbenzyl)Ni(mes)] [B(ArF)4], 19, was detected as an intermediate following chain transfer by in situ NMR studies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1901–1912, 2010
Thermal cured epoxy resins using certain calixarenes and their esterified derivatives as curing agents
Authors: Xu Shengang , Kudo Hiroto , Nishikubo Tadatomi , Nakamura Shinya , Numata Shunichi
Published: March 2010

The acetyl esterified calixarene (CA) derivatives were prepared from calix[4]resorcinarene (CRA), and p‐tert‐butylcalixarene (BCA[n], n = 4, 6, 8), respectively. Using these CA derivatives as curing agents, the thermal curing reactions of two multifunctional epoxy resins (jER 828, 186 g/equiv., and ESCN, 193.7 g/equiv.) were investigated. The temperatures of glass transition (Tg) and decomposition (T) were measured by DSC and TGA, respectively. Based on the yields, Tgs, and Tds of the thermal cured jER 828 epoxy resin with CRA‐E100, the curing conditions were optimized to be tetrabutylphosphonium bromide (TBPB) as catalyst in NMP at 160 °C for 15 h. Under this curing condition, the cured materials of jER 828 or ESCN using various CA derivatives as curing agents were prepared. Except for BCA4 derivatives, the yields of thermal curing reaction were higher than 90%. Tgs and Ts of the resultant cured materials were in the range of 113–248 °C and 363–404 °C, respectively. These results mean that the cured epoxy resins with excellent Tgs were successfully formed by using CA derivatives as curing agents. It was also found that the Tgs of cured epoxy resins were strongly affected by the degree of esterification of CA derivatives. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1931–1942, 2010
Two main chain polymeric metal complexes as dye sensitizers for dye‐sensitized solar cells based on the coordination of the ligand containing 8‐hydroxyquinoline and phenylethyl or fluorene units with Eu(III)
Authors: Xiao Lifen , Liu Yuan , Xiu Qian , Zhang Lirong , Guo Lihui , Zhang Hailiang , Zhong Chaofan
Published: March 2010

Two novel main chain polymeric metal complexes containing 8‐hydroxyquinoline europium complexes and phenylethyl or fluorene units: 1,4‐Dioctyloxy‐2,5‐bis[2‐(8‐hydroxyquinoline)‐vinyl]‐benzene Eu(III) (3) and 2,7‐bis[2‐(8‐hydroxyquinoline)‐vinyl]‐9,9′‐diocthylfluorene Eu(III) (4) with donor–acceptor‐π‐conjugated structure (D‐π‐A) have been synthesized and investigated as dye sensitizers for dye‐sensitized solar cells dyes (DSSCs). They have been determined and studied by FT‐IR, TGA, DSC, GPC, Elemental analysis, UV–vis absorption spectroscopy, photoluminescence spectroscopy, cyclic voltammetry, and application in dye‐sensitized solar cells (DSSCs) as dye sensitizers. On the basis of optimized dye and molecular structure, they have shown solar‐to‐electricity conversion efficiency 2.25% for 3 (Jsc = 4.77 mA cm−2, Voc = 630 mV, FF = 0.75) and 3.04% for 4 (Jsc = 6.33 mA cm−2, Voc = 640 mV, FF = 0.75), under the illumination of AM1.5G, 100 mW/cm2. The IPCE of 3 and 4 are 30% and 46% at 400 nm, respectively. Besides, they showed good stabilities with thermal decomposition temperatures at 280 °C and 225 °C, respectively, which are suitable for DSSCs. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1943–1951, 2010
Structured multistimuli‐responsive functional polymer surfaces obtained by interfacial diffusion of amphiphilic block copolymers
Authors: Bousquet Antoine , Ibarboure Emmanuel , Papon Eric , Labrugère Christine , Rodríguez‐Hernández Juan
Published: March 2010

Herein, we report the preparation of structured multistimuli‐responsive surfaces able to change reversibly both their chemical composition depending on the environment and their surface behavior by varying either/both the pH or/and the temperature. For that purpose, we took advantage of the surface segregation in homopolymer/diblock copolymer blends, composed of either polystyrene‐block‐poly(N,N′‐dimethylaminoethylmethacrylate) (PS‐b‐PDMAEMA) or polystyrene‐block‐poly (N,N′‐diethylaminoethylmethacrylate) (PS‐b‐PDEAEMA) and high molecular weight polystyrene used as a matrix. The variations of the surface composition as a function of the environment of exposure (air or water vapor) was investigated were investigated by XPS and contact angle measurements. The water‐annealed surfaces contain PDMAEMA or PDEAEMA at the surface and are additionally able to respond both to pH and temperature as demonstrated by the Wilhelmy technique. Both PDMAEMA and PDEAEMA can switch from a hydrophilic state to a collapsed hydrophobic state increasing the temperature above the LCST. More interestingly, as a result of the microphase separation of the block copolymers at the interface, the surfaces of the blends exhibit structuration. Thus, either micellar structures or “donut‐like” morphologies were obtained by using THF or toluene, respectively, as solvent. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1952–1961, 2010
Synthesis and electrical properties of polyaniline/polyaniline grafted multiwalled carbon nanotube mixture via in situ static interfacial polymerization
Authors: Jeon In‐Yup , Tan Loon‐Seng , Baek Jong‐Beom
Published: March 2010

The mixture of polyaniline (PANi) and PANi grafted multiwalled carbon nanotube (PANi‐g‐MWNT) was prepared by a two‐step reaction sequence. MWNT was first functionalized with 4‐aminobenzoic acid via “direct” Firedel‐Crafts acylation in polyphosphoric acid (PPA)/phosphorous pentoxide (P2O5) medium to afford 4‐aminobenzoyl‐functionalized MWNT (AF‐MWNT). Then, aniline was polymerized via an in situ static interfacial polymerization in H2O/CH2Cl2 in the presence of AF‐MWNT in organic phase to yield the mixture of PANi and PANi‐g‐MWNT. The mixture was characterized with a various analytical techniques such as elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), wide angle X‐ray diffraction (WAXD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), cyclic voltammogram (CV), UV‐vis and fluorescence spectroscopies, and electrical conductivity measurement. On the basis of TGA analysis, the thermo‐oxidative stability of the mixture was markably improved compared to that of PANi homopolymer. Even after dedoping, in alkaline solution, the mixture would still display semimetallic conductivity (4.9 S/cm). The capacitance of the mixture was also greatly enhanced and its capacitance decay with respect to cycle times was significantly reduced. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1962–1972, 2010
Synthesis and characterization of polyfluorenes containing bisphenazine units
Authors: Wang Ming , Tong Hui , Cheng Yanxiang , Xie Zhiyuan , Wang Lixiang , Jing Xiabin , Wang Fosong
Published: March 2010

Novel conjugated copolymers based on 9,9‐dioctylfluorene and bisphenazine (BP) were synthesized by Suzuki polymerization. Energy transfer from the conjugated main chain to the BP moieties was observed. Full energy transfer was achieved when the molar content of the bisphenazine was 20% (20BPPF) in toluene solution. The similar phenomena were observed even for 1% bisphenazine content copolymer (1BPPF) in film. The lowest occupied molecular orbital (LUMO) energy levels (−3.06 eV) of the copolymers were lower than that of the polyfluorene homopolymer (PFO; −2.65 eV), indicating that the introduction of the BP unit was benefit to electron injection. Single‐layer electroluminescent devices (ITO/PEDOT:PSS/polymer/LiF/Al) were fabricated to investigate their electroluminescence (EL) performances. The maximum brightness and current efficiency of all BPPF copolymers surpassed the PFO homopolymer. The best single‐layer device was based on 5BPPF, with a maximum brightness of 1532 cd/m2 and current efficiency of 1.09 cd/A. Much higher efficiency could be achieved for multilayer EL devices of 5BPPF (ITO/PEDOT:PSS/PVK/polymer/TPBI/LiF/Al), which showed a maximum current efficiency of 10.01 cd/A. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1990–1999, 2010
Effect of crosslinker multiplicity on the gel point in ATRP
Authors: Van Camp Wim , Gao Haifeng , Du Prez Filip E. , Matyjaszewski Krzysztof
Published: March 2010

The experimental gelation was studied in atom transfer radical polymerization (ATRP) of methyl acrylate (MA) with various branching reagents that structurally differ by the number of vinyl groups (multiplicity). MA was copolymerized with branching reagents containing 2, 3, 4, 5, or 6 acrylate moieties per molecule, respectively. Reactions with a constant concentration of branching vinyl groups (the same molar ratio of [Vinylbranch]0/[Initiator]0) revealed a different gelation behavior when ethylene glycol diacrylate (2A) and trimethylolpropane triacrylate (3A) were used as crosslinkers, whereas the reactions using pentaerythritol tetraacrylate (4A) showed similar gelation behavior as compared to reactions using 3A. Additional reactions with dipentaerythritol pentaacrylate (5A) and hexafunctional acrylate crosslinkers (6A) revealed the presence of a concentration‐dependant gelation behavior. On the other hand, in reactions with the same molar concentration of various crosslinkers, gelation occurred at progressively lower MA conversions for reactions with an increasing number of vinyl groups per crosslinker. In addition, the number of unreacted pendant vinyl groups in the sols was compared for reactions with different multiplicity of the crosslinker and various ratios of [Vinylbranch]0/[Initiator]0. Finally, a linear oligomeric crosslinker containing multiple branching vinyl groups along the side chain was used as the branching reagent for gelation. The gelation behavior during the ATRP of MA with the linear crosslinker was different as compared to the use of the aforementioned crosslinkers with a star‐like architecture. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2016–2023, 2010
Conjugated polymers atypically prepared in water
Authors: Invernale Michael A. , Pendergraph Samuel A. , Yavuz Mustafa S. , Ombaba Matthew , Sotzing Gregory A.
Published: March 2010

Processability remains a fundamental issue for the implementation of conducting polymer (CP) technology. A simple synthetic route toward processable precursors to CPs (main chain and side chain) was developed using commercially available materials. These soluble precursor systems were converted to conjugated polymers electrochemically in aqueous media, offering a cheaper and greener method of processing. Oxidative conversion in aqueous and organic media each produced equivalent electrochromics. The precursor method enhances the yield of the electrochromic polymer obtained over that of electrodeposition, and it relies on a less corruptible electrolyte bath. However, electrochemical conversion of the precursor polymers often relies on organic salts and solvents. The ability to achieve oxidative conversion in brine offers a less costly and a more environmentally friendly processing step. It is also beneficial for biological applications. The electrochromics obtained herein were evaluated for electronic, spectral, and morphological properties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2024–2031, 2010
Compatible and tearing properties of poly(lactic acid)/poly(ethylene glutaric‐co‐terephthalate) copolyester blends
Authors: Yeh Jen‐Taut , Tsou Chi‐Hui , Lu Wei , Li Ya‐Ming , Xiao Han Wen , Huang Chi‐Yuan , Chen Kan‐Nan , Wu Chin‐San , Chai Wan‐Lan
Published: March 2010

Fourier transform infrared and nuclear magnetic resonance results suggest that the carboxylic acid groups of poly(lactic acid) (PLA) molecules react with the hydroxyl groups of FePol (FP) molecules during the melt‐blending of PLAxFPy specimens. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) experiments of PLA and PLA/FP specimens suggest that only small amounts of poor PLA and/or FP crystals are present in their corresponding melt crystallized specimens. In fact, the percentage crystallinity, peak melting temperature, and onset re‐crystallization temperature values of PLA/FP specimens reduce gradually as their FP contents increase. However, the glass transition temperatures of PLA molecules found by DSC and DMA reduce to a minimum value as the FP contents of PLAxFPy specimens reach 6 wt %. Further DMA and morphological analysis of PLA/FP specimens reveal that FP molecules are compatible with PLA molecules at FP contents equal to or less than 6 wt %, as no distinguished phase‐separated FP droplets and tan δ transitions were found on fracture surfaces and tan δ curves of PLA/FP specimens, respectively. In contrast to PLA, the FP specimen exhibits highly deformable and tearing properties. After blending proper amounts of FP in PLA, the inherent brittle deformation and poor tearing behavior of PLA were successfully improved. Possible reasons accounting for these interesting crystallization, compatible and tearing properties of PLA/FP specimens are proposed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 913–920, 2010
Morphology evolution of polypropylene in immiscible polymer blends for fabrication of nanofibers
Authors: Xue Chao Hua , Wang Dong , Xiang Bei , Chiou Bor‐sen , Sun Gang
Published: March 2010

Immiscible blends of cellulose acetate butyrate (CAB) and isotactic polypropylenes (iPPs) with different melting index were extruded through a two‐strand rod die. The extrudates were hot‐drawn at the die exit at different draw ratios by controlling the drawing speed. The morphologies of iPP fibers extracted from the as‐obtained extrudates after removal of CAB by acetone were investigated by scanning electron microscopy. The influences of draw ratio, viscosity ratio, and composition ratio of CAB/iPP on the morphology evolution of iPP phase into nanofibers in the immiscible blends were studied. It was found that the thermoplastic iPP nanofibers were formed from the elongation of iPP ellipsoids, end‐to‐end merging of elongated iPP microfibers, and the size decrease of iPP microfibers in the processes of extrusion and drawing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 921–931, 2010
Physical characteristics and properties of waterborne polyurethane materials reinforced with silk fibroin powder
Authors: Tao Yongzhen , Yan Yun , Xu Weilin
Published: March 2010

Degummed silk filament was pulverized with a home‐made machine to obtain silk fibroin (SF) powder, and the structure, morphology, and particle size of the SF powder were investigated. The individual spherical particles and aggregates with different morphology of silk fibroin coexisted in water. A waterborne polyurethane (WPU) aqueous dispersion was blended with the SF powder to prepare novel blended materials with improved physical properties. The average particle size and zeta potential of the WPU/SF aqueous dispersions were characterized. The result showed that the WPU/SF dispersion with higher SF content exhibited a less negative zeta potential and a larger average particle size. Furthermore, the effect of SF content on the morphology, miscibility, and mechanical properties of the resulting blended films was studied by scanning electron microscopy, wide‐angle X‐ray diffraction, dynamic mechanical thermal analysis, and tensile testing. The films showed an improved Young's modulus and tensile strength from 0.3 to 33.8 MPa, and 0.6 to 5.2 MPa, respectively, with the increasing of SF up to a content of 26 wt %. The negative charges in the periphery and the small particle size made a good effort on dispersing SF powder into the WPU matrix as small aggregates, and the SF powder led to the efficient strengthening of WPU materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 940–950, 2010
Effects of solvent, casting temperature, and guest/host stoichiometries on the properties of shape memory material based on partial α‐CD‐PEG inclusion complex
Authors: Yu Zhijun , Liu Yan , Fan Minmin , Meng Xianwei , Li Bangjing , Zhang Sheng
Published: March 2010

A series of supramolecular inclusion complex (IC) films were formed by threading α‐cyclodextrin (α‐CD) molecules over poly(ethylene glycol) (PEG), according to the designed ratio of α‐CD/PEG. Because of containing α‐CD‐PEG inclusion crystallites as physical crosslinks and uncovered PEG crystallites as “switch phase”, the resulting supramolecular α‐CD‐PEG partial ICs displayed a shape memory effect. The properties of the materials were investigated by 1H‐NMR, X‐ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and swelling measurement. It was found that the casting temperature, solvent, and the ratio of α‐CD‐PEG inclusion/PEG had great influence on the formation and properties of α‐CD‐PEG partial ICs. The modes of complexes on different conditions were proposed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 951–957, 2010
Interplay between bulk viscoelasticity and surface energy in autohesive tack of rubber‐tackifier blends
Authors: Kumar K. Dinesh , Tsou Andy H. , Bhowmick Anil K.
Published: March 2010

The effects of change in surface energy and bulk viscoelastic properties on the autohesive tack strength of brominated isobutylene‐co‐p‐methylstyrene (BIMS) rubber have been investigated by the addition of hydrocarbon resin (HCR) tackifier and maleated hydrocarbon resin (MA‐g‐HCR) tackifier. The addition of compatible HCR tackifier results in a reasonable increment in the tack strength of BIMS rubber by modifying only the bulk viscoelastic properties (compliance, entanglement molecular weight, relaxation time, self‐diffusion, and monomer friction coefficient values) of BIMS rubber to perform better during the course of bonding and debonding steps of the peel test. Incorporation of MA‐g‐HCR tackifier (containing 5–20 wt % of grafted maleic anhydride) steadily increases the tack strength of BIMS rubber further by precisely modifying both the surface energy and bulk viscoelastic properties to perform much better in the bonding and debonding steps. However, beyond 20 wt % of grafted maleic anhydride in the HCR tackifier, the tack strength starts decreasing due to the incompatibility between the blend components, and hence, the bulk viscoelastic properties required for bond formation are severely retarded by the interrelated reinforcing effect and the phase separation effect of the brittle MA‐g‐HCR tackifier in the BIMS rubber. Hence, the polar groups in a tackifier will contribute to significant enhancement of autohesive tack strength only if the bulk viscoelastic property of the rubber‐tackifier blend is favorable for bond formation and bond separation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 972–982, 2010
Influence of physical aging on the performance of corona‐charged amorphous polymer electrets
Authors: Erhard Dominik P. , Lovera Deliani , Giesa Reiner , Altstädt Volker , Schmidt Hans‐werner
Published: March 2010

The influence of physical aging on the electret properties before corona charging of three amorphous polymers, polyetherimide (PEI), poly(phenylene ether) (PPE), and polystyrene (PS), as well as with blends of PPE and PS, was investigated. The degree of aging was monitored by determining the enthalpy relaxation Δh using differential scanning calorimetry (DSC). The electret performance was evaluated by isothermal potential decay (ITPD) at elevated temperatures and by thermal stimulated discharge (TSD) measurements. It was demonstrated that physical aging below the glass transition temperature substantially improves the electret performance of amorphous polymers by reducing the free volume and thus hindering charge motion. As an example, the performance of nonaged PEI was improved by physical aging at 200 °C for 4 days from 18 to 95% retained charge after 24 h at 120 °C. A similar beneficial influence of physical aging on the charge storage capability was achieved using blends of PPE with PS. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 990–997, 2010
Attractions to radiation‐like eras in superstring cosmologies
Authors: Partouche H.
Published: March 2010

We review the cosmology induced by finite temperature and quantum effects on non‐supersymmetric string models. We show the evolution is attracted to radiation‐like solutions after the Hagedorn era and before the electroweak phase transition. This mechanism generates a hierarchy between the Planck mass and the supersymmetry breaking scale. A dynamical change of space‐time dimension can take place.
Compatibility of traditional and novel acaricides with bumblebees (Bombus terrestris): a first laboratory assessment of toxicity and sublethal effects
Authors: Besard Linde , Mommaerts Veerle , Vandeven Jessica , Cuvelier Xavier , Sterk Guido , Smagghe Guy
Published: March 2010

BACKGROUND: This project assessed the potential hazards of different classical and novel acaricides against an important non‐target and beneficial insect for the pollination of wild flowers and cultivated crops, the bumblebee Bombus terrestris (L). Twenty‐three acaricides used commercially in the control of phytophagous mites (Acari) were tested in greenhouses and/or the open field. Side effects included acute mortality and also sublethal effects on nest reproduction. The different compounds were administered in the laboratory via three different worst‐case field scenario routes of exposure: dermal contact and orally via the drinking of treated sugar water and via treated pollen. The compounds were tested at their respective maximum field recommended concentration (MFRC), and, when strong lethal effects were observed, a dose–response assay with a dilution series of the MFRC was undertaken to calculate LC50 values.

RESULTS: From the different acaricide classes, several chemistries caused high levels of acute toxicity in bumblebee workers, especially bifenthrin and abamectin which resulted in 100% mortality by contact. In addition, several acaricides tested were found to have a detrimental effect on drone production. For oral exposures via treated sugar water, the dose–response assay showed the LC50 values for abamectin, bifenazate, bifenthrin and etoxazole to be 1/15 MFRC (1.17 mg AI L−1), 1/10 MFRC (9.6 mg AI L−1), 1/83 MFRC (0.36 mg AI L−1) and 1/13 MFRC (4.4 mg AI L−1) respectively, indicating that their use should be carefully evaluated.

CONCLUSION: Overall, the results suggest that most of the acaricides tested are compatible with bumblebees, with the exceptions of abamectin, bifenazate, bifenthrin and etoxazole. However, the risks also depended on the type of treatment. As a result, the sugar water treatment seems to present the worst‐case situation of exposure, indicating that this approach is suitable for determining the hazards of pesticides against bumblebees. Finally, it is suggested that future tier testing under more field‐related conditions is required for a final decision of their risks. Copyright © 2010 Society of Chemical Industry
Probing the magnetism of nanostructures buried in metallic surfaces and their possible utilization
Authors: Brovko Oleg O. , Stepanyuk Valeri S.
Published: March 2010

We discuss the possibility to probe magnetic properties of nanostructures buried beneath a metallic surface by means of local probe techniques. We prove, that those properties can be deduced from the spin‐resolved local density of states (LDOS) above the surface. In‐plane polarization maps in vacuum above the surface are shown to allow one to simultaneously detect electronic, magnetic, and even geometric properties of subsurface structures. It is argued, that the coupling of buried nanostructures to each other can be deduced from the symmetry of the polarization map. To underline the importance of studying buried nanostructures several possible applications of buried magnetic impurities are pointed out. The exchange coupling of an adatom to a nanostructure or a monolayer (ML) across a paramagnetic spacer is shown to oscillate with the thickness of the latter. This could provide one with reliable means to stabilize the spin of a magnetic adatom in either a ferromagnetic or an antiferromagnetic configuration with respect to the magnetic orientation of the monolayer or nanostructure. The possibility to tailor the exchange coupling between single magnetic impurities on a surface through the adjustment of the overlayer thickness and the interatomic separation in a dimer, is discussed.
Multiple surface‐plasmon‐polariton waves localized to a metallic defect layer in a sculptured nematic thin film
Authors: Faryad Muhammad , Lakhtakia Akhlesh
Published: March 2010

The propagation of a surface‐plasmon‐polariton (SPP) wave guided by a thin metallic defect layer in a sculptured nematic thin film (SNTF) – a periodically nonhomogeneous, anisotropic, dielectric material – was studied theoretically. If the defect layer is sufficiently thick, SPP waves propagate independently along the two metal/SNTF interfaces formed by the presence of the defect layer in the SNTF. As the thickness of the defect layer is reduced, SPP wave propagation is modified by the coupling of the two interfaces. The number of SPP waves increases and lower attenuation rates along the direction of propagation become possible.

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(© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Antihyperglycaemic and protective effects of flavonoids on streptozotocin–induced diabetic rats
Authors: Rauter Amélia P. , Martins Alice , Borges Carlos , Mota‐Filipe Helder , Pinto Rui , Sepodes Bruno , Justino Jorge
Published: March 2010

The antihyperglycaemic effect of eight standard flavonoids, previously identified in the ethanol extract of the claimed antidiabetic plant Genista tenera, was evaluated on streptozotocin (STZ)‐induced diabetic Wistar rats. The aglycones apigenin, chrysoeriol and genistein, the monoglucosides apigenin 7‐O‐glucoside, luteolin 7‐O‐glucoside and genistein 7‐O‐glucoside and the diglycosides rutin and luteolin 7,3′‐di‐O‐glucoside were administered i.p. for 7 days (4 mg/kg b.w./day). The protective effect of these compounds over liver and kidneys of STZ–diabetic models was also evaluated by the determination of seric AST, ALT and urea levels. After 7 days of treatment, apigenin, chrysoeriol and genistein significantly lowered the blood glucose levels of diabetic animals; this effect was more pronounced (P < 0.01) in the oral glucose tolerance test. Glucose tolerance was also significantly improved in the rutin (P < 0.01) and in the genistein 7–O–glucoside (P < 0.05) treated groups. In addition, almost all the tested compounds effectively protected the liver and kidneys against STZ‐induced damage in rats. Copyright © 2010 John Wiley & Sons, Ltd.
State estimation of convective storms with a two‐moment microphysics scheme and an ensemble Kalman filter: Experiments with simulated radar data
Authors: Xue Ming , Jung Youngsun , Zhang Guifu
Published: March 2010

The ability of the ensemble Kalman filter method to estimate an increased number of state variables associated with a double‐moment (DM) microphysics scheme is examined for the first time through observing system simulation experiments, assuming either a perfect or imperfect prediction model and/or observation operators. With the DM scheme, mixing ratios and total number concentrations of hydrometeor species are predicted.

It is found that the increased number of state variables can be reasonably well estimated when both radial velocity (Vr) and reflectivity (ZH) observations are used and when the prediction model is assumed to be perfect. However, the errors increase significantly when ZH is used alone. In this case, the filter has difficulty in estimating independently‐varying mixing ratios and number concentrations, which are both directly involved in the calculation of ZH. The addition of Vr data helps alleviate a problem associated with the solution not being sufficiently constrained by observations.

With the DM scheme, the correlations between ZH and model state variables exhibit complex spatial structures that depend on the location of the ZH observation. Collocated ZH and vertical velocity show negative correlation when the observation is taken where ice phase hydrometeors are dominant, but positive correlation when it is taken where large quantities of liquid hydrometeors exist. Further study is needed to fully understand the complex correlation structures.

Imperfect model experiments were performed, with two types of model errors: (1) microphysical parametrization error due to incorrectly assumed shape parameter of the gamma particle size distribution (PSD), and (2) different ways of calculating hydrometeor scattering. The results show that the model error degrades the state estimation in general. Nevertheless, the estimated states are still reasonably good when both Vr and ZH are assimilated. Perturbing the shape parameter of gamma PSDs within the forecast ensemble improves the overall state estimation. Copyright © 2010 Royal Meteorological Society
Corrective osteotomy using customized hydroxyapatite implants prepared by preoperative computer simulation
Authors: Oka Kunihiro , Murase Tsuyoshi , Moritomo Hisao , Goto Akira , Sugamoto Kazuomi , Yoshikawa Hideki
Published: March 2010

Background

Opening wedge corrective osteotomy usually requires a bone graft. However, it is difficult to shape the graft into an appropriate configuration. To resolve this problem, we developed an original computer program system that calculates the size and shape of a bone graft and cuts a hydroxyapatite block into the desired shape.

Methods

Five patients with forearm deformity were included in this study. The amount of deformity and the three‐dimensional (3D) shape of the bone graft to be inserted into the osteotomy site were calculated and designed by comparing bilateral 3D bone models. For the bone graft, a block of hydroxyapatite was cut based on the preoperative simulation. In addition, a customized osteotomy template was designed and manufactured before surgery, based on preoperative simulations and used during the actual operation.

Results

Corrective osteotomy based on simulations was achieved in all cases. The average angular deformities on anteroposterior and lateral radiographs were decreased from 16.8° to 1.2° and from 16.6° to 0.6°, respectively, after surgery. All patients had bone fusion within 5 months.

Conclusions

Customized hydroxyapatite implants are helpful for accurate correction and good functional results. Copyright © 2010 John Wiley & Sons, Ltd.
Programming in the complex: Cybernetic insights into software process and architecture
Authors: Donaires Omar Sacilotto
Published: March 2010

This paper introduces the concept of programming in the complex to designate the development and maintenance of complex software systems in situations where the software process and the software architecture need to change dynamically in order to cope with the impact of unpredicted and frequent environmental changes. The article proposes a systemic‐cybernetic process model, which is a composition of Stafford Beer's viable system model (VSM) and Barry Boehm's spiral model. The VSM provides adaptability to the software architecture and self‐organizing capability to the software process. As a result of the application of the VSM, four relevant insights are presented. Copyright © 2010 John Wiley & Sons, Ltd.
3D‐FE Modelling and Simulation of Multi‐way Loading Process for Multi‐ported Valves
Authors: Zhang D. W. , Yang H. , Sun Z. C.
Published: March 2010

Multi‐ported valves are widely used in the marine, sanitary, petrochemical and power industry. Multi‐way loading forming technology provides an efficient approach for integral forming of high strength multi‐ported valves, such as tee pipe coupling, high‐pressure cross valves, large‐scale complex valves, and so on. Since the multi‐way loading process is a very complicated plastic forming process due to the complexity of loading path, finite element numerical simulation is adopted to investigate the multi‐way loading process in order to predict and control the multi‐ported valve forming process. A reasonable model of the process is developed under DFEORM‐3D environment based on the coupled thermo‐mechanical finite element method. Then the reliability of the model is validated with respect to geometry development and forming defects. Numerical simulations of multi‐way loading forming for a tee valve and a cross valve have been carried out via using the developed model. Further, the forming processes of tee valve and cross valve have been compared. Moreover, the modelling method is also suitable for multi‐way loading processes of other complex components.
Intratumoral Hypoxic Gradient Drives Stem Cells Distribution and MGMT Expression in Glioblastoma
Authors: Pistollato Francesca , Abbadi Sara , Rampazzo Elena , Persano Luca , Della Puppa Alessandro , Frasson Chiara , Sarto Eva , Scienza Renato , D'avella Domenico , Basso Giuseppe
Published: March 2010

Glioblastoma multiforme (GBM) are highly proliferative tumors currently treated by surgical removal, followed by radiotherapy and chemotherapy, which are counteracted by intratumoral hypoxia. Here we exploited image guided surgery to sample multiple intratumoral areas to define potential cellular heterogeneity in correlation to the oxygen tension gradient within the GBM mass. Our results indicate that more immature cells are localized in the inner core and in the intermediate layer of the tumor mass, whereas more committed cells, expressing glial fibrillary acidic protein and β-III-tubulin, are distributed along the peripheral and neo-vascularized area, where Smad1/5/8 and Stat3 result to be activated. Moreover, GBM stem cells, identified with the stem cell marker CD133, express high level of DNA repair protein O6-methylguanine-DNA-methyltransferase (MGMT) known to be involved in chemotherapy resistance and highly expressed in the inner core of the tumor mass. Importantly, these cells and, particularly, CD133+ cells result to be resistant to temozolomide (TMZ), the most used oral alkylating agent for the treatment of GBM, which specifically causes apoptosis only in GBM cells derived from the peripheral layer of the tumor mass. These results indicate a correlation between the intratumoral hypoxic gradient, the tumor cell phenotype, and the tumor resistance to chemotherapy leading to a novel concentric model of tumor stem cell niche, which may be useful to define the real localization of the chemoresistant GBM tumor cells in order to design more effective treatment strategies.
Language and conceptual development
Authors: Arunachalam Sudha , Waxman Sandra R.
Published: March 2010

Linguistic and conceptual development converge crucially in the process of early word learning. Acquiring a new word requires the child to identify a conceptual unit, identify a linguistic unit, and establish a mapping between them. On the conceptual side, the child has to not only identify the relevant part of the scene being labeled, but also isolate a concept at the correct level of abstraction—the word ‘dog’ must be mapped to the concept dog and not to the concepts petting or collie, for example. On the linguistic side, the child must use the syntactic context in which the word appears to determine its grammatical category (e.g., noun, verb, adjective). But she also uses syntactic information, along with observation of the world and social‐communicative cues, to make guesses at which concept the word picks out as well as its level of abstraction. We present evidence that young learners learn new words rapidly and extend them appropriately. However, the relative import of observational and linguistic cues varies as a function of the kind of word being acquired, with verbs requiring a richer set of conceptual and linguistic cues than nouns. Copyright © 2010 John Wiley & Sons, Ltd.

This article is categorized under:

Linguistics > Language Acquisition

Psychology > Language
Memory systems
Authors: Eichenbaum Howard
Published: March 2010

The idea that there are multiple memory systems can be traced to early philosophical considerations and introspection. However, the early experimental work considered memory a unitary phenomenon and focused on finding the mechanism upon which memory is based. A full reconciliation of debates about that mechanism, and a coincidental rediscovery of the idea of multiple memory systems, emerged from studies in the cognitive neuroscience of memory. This research has identified three major forms of memory that have distinct operating principles and are supported by different brain systems. These include: (1) a cortical‐hippocampal circuit that mediates declarative memory, our capacity to recollect facts and events; (2) procedural memory subsystems involving a cortical‐striatal circuit that mediates habit formation and a brainstem‐cerebellar circuit that mediates sensorimotor adaptations; and (3) a circuit involving subcortical and cortical pathways through the amygdala that mediates the attachment of affective status and emotional responses to previously neutral stimuli. Copyright © 2010 John Wiley & Sons, Ltd.

This article is categorized under:

Psychology > Memory

Neuroscience > Cognition
Asymmetry of interhemispheric communication
Authors: Alberto Marzi Carlo
Published: March 2010

The role of the corpus callosum (CC) in ensuring communication between the cerebral hemispheres is an undisputed great discovery of the 20th century. In the past 20 years, it has been repeatedly shown by behavioral and electrophysiological experiments that callosal transmission is asymmetric. It is faster from the right to the left hemispheres for a host of behavioral and cognitive processes. The functional meaning and the neural bases of the asymmetry are still being investigated but one possibility is that it is related to a larger proportion of cortical neurones, projecting their axon from the right to the left hemisphere than in the reverse direction in the CC. This asymmetry might be related to the necessity to rapidly access the left hemisphere for response during tasks mainly subserved by the right hemisphere. Copyright © 2010 John Wiley & Sons, Ltd.

This article is categorized under:

Psychology > Brain Function and Dysfunction

Neuroscience > Anatomy