bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enthalpy and Entropy Contributions to Solvent Quality and Inversions of Heat Effects with Polymer Concentration
Authors: Bercea Maria , Wolf Bernhard A. 
Published: September 2006

AbstractSummary: Vapor pressures above the solutions of polystyrene in either cyclohexane (32–60 °C) or toluene (10–70 °C) have been measured by a combination of head space sampling and gas chromatography as a function of the volume fraction φ of the polymer. The thus obtained Flory‐Huggins interaction parameters χ (φ; T) were complemented by data for three other systems (tert‐butyl acetate/polystyrene, cyclohexane/poly(vinyl methyl ether), 2‐propanol/poly(butyl methacrylate)) reported in the literature and analyzed in terms of their enthalpy and entropy parts χH and χS. Furthermore these experimental findings were modeled by means of an approach splitting the mixing process conceptually into two parts and leading to the expression χ = χfc + χcr. The first step takes place at fixed conformation of the components and yields χfc; equilibrium is reached in the second step, during the conformational relaxation, contributing χcr. The results demonstrate that mixing can either be driven enthalpically or entropically. By contrast the conformational response acts in all cases towards homogeneous mixing. The inversion of heat effects observed for two of the five systems can be well modeled in terms of the composition dependence of the enthalpy parts of χfc and χcr.Composition dependence of the enthalpy part, χH, of the Flory‐Huggins interaction parameter, and of the heat effects associated with the dilution in two steps.magnified imageComposition dependence of the enthalpy part, χH, of the Flory‐Huggins interaction parameter, and of the heat effects associated with the dilution in two steps.
Phenolic Resin and Derived Carbon Hollow Spheres
Authors: Yang Mu , Ma Jin , Ding Shujiang , Meng Zhaokai , Liu Jinge , Zhao Tong , Mao Lanqun , Shi Yi , Jin Xigao , Lu Yunfeng , Yang Zhenzhong 
Published: September 2006

AbstractSummary: Phenolic formaldehyde (PF) resins are attractive due to their excellent performances such as high temperature resistance, thermal abrasion, and high yield of carbon conversion. In this communication, PF resin‐based composite hollow spheres were fabricated by in situ favorable absorption and catalytic crosslinking of PF resin within sulfonated polystyrene gel layers of the hollow sphere templates at low temperature. The composite hollow spheres were achieved in one step, avoiding traditional removal of template cores. The intact shell was tuned from double‐layered to single‐layered. Carbon hollow spheres with porous shell were derived by carbonization of the PF composite hollow spheres. Metal/carbon composite hollow spheres were further synthesized by the incorporation of metal within the porous shell, which would be a promising material for catalysis.TEM image of carbon double‐shelled hollow spheres after the PF composite spheres are calcined at 800 °C for 2 h in nitrogen.magnified imageTEM image of carbon double‐shelled hollow spheres after the PF composite spheres are calcined at 800 °C for 2 h in nitrogen.
Novel Anionic Photoacid Generators (PAGs) and Corresponding PAG Bound Polymers
Authors: Wang Mingxing , Gonsalves Kenneth E. , Yueh Wang , Roberts Jeanette M. 
Published: September 2006

AbstractSummary: A new series of functionalized anionic photoacid generators (PAGs), and corresponding polymers were prepared in moderate to good yield and characterized. The thermostability of PAG bound polymers was superior to PAG blend polymers. The fluorine‐free PAG bound or blend polymers exhibited higher stability than fluorine‐substituted PAG bound or blend polymers. Although the acid generating efficiency of PAG blend polymers was higher than that of PAG bound polymers, yet it is anticipated that PAG incorporated into the polymer main chain may improve acid diffusion compared with the PAG blend polymers. This was demonstrated by preliminary electron beam lithography (EBL) results: the fluorine PAG bound polymer resist HE‐F4‐MBS‐TPS gave 35 nm 1:1 L/S and showed better resolution than the blend sample HE Blend F4‐IBBS‐TPS. The PAG bound resist showed the capability for higher resolution, since 30 nm 2:1 L/S patterned. Based on these preliminary EBL results, the PAG bound polymer samples are anticipated to have a resolution capability for the 32 nm node for EUVL.Design of microstructures for EUV lithography.magnified imageDesign of microstructures for EUV lithography.
Crystallization of Poly(ε‐caprolactone)/Poly(vinyl chloride) Miscible Blends Under Strain: The Role of Molecular Weight
Authors: Zhang Yubao , Prud'homme Robert E. 
Published: September 2006

AbstractSummary: The effect of poly(ε‐caprolactone) (PCL) molecular weight on the orientation of crystalline PCL in miscible poly(ε‐caprolactone)/poly(vinyl chloride) (PCL/PVC) blends, melt crystallized under strain, has been studied by a combination of wide angle X‐ray diffraction (WAXD) and small angle X‐ray scattering (SAXS) studies. An unusual crystal orientation with the b‐axis parallel to the stretching direction was observed in miscible PCL/PVC blends with PCL of high molecular weight (>21 000). SAXS showed the presence of nanosize confined PCL in the PCL/PVC blends, which could be preserved at temperatures higher than the Tm of PCL but lower than the Tg of PVC. A mechanism based on the confinement of PCL crystal growth was proposed, which can explain the formation of b‐axis orientation in PCL/PVC blends crystallized under strain.SAXS pattern of stretched PCL/PVC blend after annealing at 90 °C for 5 min.magnified imageSAXS pattern of stretched PCL/PVC blend after annealing at 90 °C for 5 min.
Scale‐up of Microwave‐Assisted Polymerizations in Batch Mode: The Cationic Ring‐Opening Polymerization of 2‐Ethyl‐2‐oxazoline
Authors: Hoogenboom Richard , Paulus Renzo M. , Pilotti Åke , Schubert Ulrich S. 
Published: September 2006

AbstractSummary: The use of microwave heating in polymer science is a rapidly growing field of research leading to faster and cleaner polymerization procedures. However, the majority of the investigations are performed at small scales (≈1 mL), which is far away from potential commercial applications of microwave‐assisted polymerizations. In addition, it has been shown in organic chemistry that microwave‐assisted reaction protocols can be directly scaled without the need for process optimization. In this contribution, we have investigated the direct scaling of microwave‐assisted polymerization procedures under pressure conditions using the cationic ring‐opening polymerization of 2‐ethyl‐2‐oxazoline as the model system. This polymerization was performed at scales ranging from 4.0 mmol (1 mL) to 1.0 mol (250 mL) in different microwave synthesizers covering both monomode and multimode devices.Scale‐up of microwave‐assisted polymerizations in batch mode: the cationic ring‐opening polymerization of 2 ethyl‐2‐oxazoline.magnified imageScale‐up of microwave‐assisted polymerizations in batch mode: the cationic ring‐opening polymerization of 2 ethyl‐2‐oxazoline.
Effects of Annealing on the Migration Behavior of PA6/Clay Nanocomposites
Authors: Tang Yong , Lewin Menachem , Pearce Eli M. 
Published: September 2006

AbstractSummary: Migration of clay to the surface of nylon 6‐organically modified clay is investigated. The effect of annealing time and temperature on the migration of the clay is reported. Attenuated total reflectance FT‐IR spectrometry, X‐ray diffraction, and high‐resolution electronic microscopy are used in this study. The results obtained indicate that migration occurs predominantly in the samples with exfoliated structure. Migration increases in the temperature range of 250–275 °C. A further increase in temperature decreases the extent of migration. Migration increases with time at 250 °C. Annealing in the presence of oxygen decreases migration. It is suggested that the extent of migration depends on the concentration of the surfactant and the polymer in the exfoliated particles.High‐resolution electronic microscopy image of an exfoliated nylon‐6/clay sample in which migration has occurred.magnified imageHigh‐resolution electronic microscopy image of an exfoliated nylon‐6/clay sample in which migration has occurred.
Mechanical Properties of the Nanometer Scale Precrystalline Order of a Poly(ethylene terephthalate)/Poly(ethylene naphthalate) Blend
Authors: Tranchida Davide , Kiflie Zebene , Piccarolo Stefano 
Published: September 2006

AbstractSummary: Nanometer scale morphological order of macroscopically amorphous polyesters, obtained from the melt at moderate cooling rates, was observed in the past. The effect of such order on mechanical properties of a PET/PEN blend, evaluated by AFM nanoindentations, is reported in this study. Results show that nanoindentations conducted at relatively high load, with penetration depths of the order of 100 nm, confirm the information obtained from mechanical tests at micrometer scale, i.e., microhardness. On the other hand, true nanometer scale indentations (<40 nm) are seen to discriminate between the mechanical properties of the nanophases formed during solidification.Statistical distribution of elastic moduli observed after 60 nanoindentations performed at 1 µN on each sample solidified at the cooling rates reported in the legend.magnified imageStatistical distribution of elastic moduli observed after 60 nanoindentations performed at 1 µN on each sample solidified at the cooling rates reported in the legend.
99: are retailers best responding to rational consumers? Experimental evidence
Authors: Ruffle Bradley J. , Shtudiner Ze'ev 
Published: September 2006

AbstractThere exist numerous theories that attempt to explain the ubiquitous 99‐cent price ending. Most of these theories either do not hold up to inspection or posit irrational consumers who serve as a money pump for firms. We offer an experimental test of Basu's (Econ. Lett. 1997; 54:41–44) rational expectations equilibrium model in which consumers are fully rational. We find partial support for Basu's model. Convergence to the 99‐cent equilibrium is faster and more widespread when firms are able to observe the previous pricing decisions of others. By imitating the optimal 99‐cent price endings of rational firms, less rational firms display an ‘as if’ rationality. Copyright © 2006 John Wiley & Sons, Ltd.
Option pricing by students and professional traders: a behavioural investigation
Authors: Abbink Klaus , Rockenbach Bettina 
Published: September 2006

AbstractWe compare behaviour of students and professional traders from an influential German bank in an option pricing experiment. The arbitrage free price is independent of the probability distribution of the underlying asset. Students show a probability‐dependent option valuation, but learn to exploit more arbitrage with experience. The professional traders exhibit a less probability sensitive valuation, but their performance is lower than the students'. We explain this with a more intuitive and less analytic approach used by the professional traders, despite their superior knowledge of financial markets, due to the lack of known probability distributions in real markets. Copyright © 2006 John Wiley & Sons, Ltd.
Benefit packages and individual behavior: choices over discrete goods with multiple attributes
Authors: Boening Mark Van , Blackstone Tanja F. , McKee Michael , Rutstrom Elisabet 
Published: September 2006

AbstractManagers and employers use an array of rewards to attract and retain quality employees. An increasingly significant component of the overall compensation is the employee's benefits package. Flexible packages offer more choice but also incur higher decision costs. We conduct an experiment on choices over stylized benefits packages where discrete ‘goods’ have multiple attributes affecting the payoff function. We investigate the degree to which these complications affect choices. Eighty subjects play an individual‐choice decision‐cost game where they are implicitly asked to solve a complex programming problem. Our main results are that: (a) individual subjects respond to the relative tradeoff between the attributes, (b) some combinations of the attributes (apparently) entice subjects to search more and thus earn more, and (c) most subjects appear to adopt a heuristic that approximates the optimal solution. Further, subjects appear to value the right to make choices, as they rarely choose a fixed payoff option with a known payoff and low decision cost, even when the fixed payoff is 80% of the maximum possible under the decision‐making task. Copyright © 2006 John Wiley & Sons, Ltd.
Elastoplastic medium for foundation settlements and monotonic soil–structure interaction under combined loadings
Authors: Conniff Dawn E. , Kiousis Panos D. 
Published: September 2006

AbstractFoundation settlements and soil–structure interaction are important problems to structural and geotechnical engineers. This study introduces a novel elastoplastic three‐degree‐of‐freedom medium which models foundations settlements under combined loadings. A soil–structure interaction problem can then be solved by replacing the soil mass with this three‐degree‐of‐freedom elastoplastic medium, thus reducing significantly the size of the problem. The model was developed by extending the classical plasticity concepts to the force‐deformation level. Its ability to predict foundation deformations was evaluated using finite element solutions of a typical shallow foundation problem and was found reasonably accurate while producing significant time savings. Copyright © 2006 John Wiley & Sons, Ltd.
Characterization and over‐expression of chaperonin t‐complex proteins in colorectal cancer
Authors: Coghlin C , Carpenter B , Dundas SR , Lawrie LC , Telfer C , Murray GI 
Published: September 2006

AbstractThe chaperonins are key molecular complexes, which are essential in the folding of proteins to produce stable and functionally competent protein conformations. One member of the chaperonin group of proteins is TCP1 (chaperonin containing t‐complex polypeptide 1, or CCT), but little is known about this protein in tumours. In this study, we used comparative proteomic analysis to show that t‐complex protein subunits TCP1 beta and TCP1 epsilon are over‐expressed in colorectal adenocarcinomas. Monoclonal antibodies to these proteins were developed and the expression and cellular localization of these two proteins in colorectal cancer were analysed by immunohistochemistry on a colorectal cancer tissue microarray. In colorectal cancer, TCP1 beta cellular localization was exclusively cytoplasmic, whereas TCP1 epsilon staining was seen in both the nucleus and the cytoplasm. Both cytoplasmic TCP1 beta and cytoplasmic TCP1 epsilon were significantly over‐expressed (p < 0.001 for each protein) in primary colorectal cancer and also showed increased expression with advancing Dukes' stage (p = 0.018 for TCP1 beta and p = 0.045 for TCP1 epsilon). A trend was also identified between over‐expression of cytoplasmic TCP1 beta and reduced patient survival (p = 0.05). These results show that both TCP1 beta and TCP1 epsilon are over‐expressed in colorectal cancer and indicate a role for TCP1 beta and TCP1 epsilon in colorectal cancer progression. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
TLR‐2‐mediated induction of vascular endothelial growth factor (VEGF) in cartilage in septic joint disease
Authors: Varoga D , Paulsen F , Mentlein R , Fay J , Kurz B , Schütz R , Wruck C , Goldring MB , Pufe T 
Published: September 2006

AbstractBacterial arthritis is a progressive joint disease which includes rapid destruction of articular cartilage even after clearance of the causal factor. The resulting post‐infectious arthropathy is mainly characterized by self‐perpetuating joint destruction and extensive angiogenesis in the emerging pannus‐like synovial membrane, but the underlying molecular mechanisms of the bacteria‐initiated process remain incompletely understood. This study was conducted to elucidate the expression and regulation of angiogenic and cartilage‐destructive vascular endothelial growth factor (VEGF) in septic arthritis. For that purpose, aspirates of synovial fluid from patients with pyogenic arthritis were examined for VEGF levels by ELISA. In vitro studies with primary and immortalized chondrocytes were performed to determine whether Gram‐positive and Gram‐negative bacteria induce VEGF expression, by using real‐time RT‐PCR, ELISA, and immunohistochemistry. Activation of the transcription factor AP‐1 was assessed by EMSA experiments. The necessity of the Toll‐like receptor‐2 (TLR‐2), ERK‐1/‐2, and AP‐1 pathway for infectious VEGF induction in chondrocytes was examined by using specific blocking reagents. ELISA experiments revealed that aspirates of synovial fluid from patients with pyogenic arthritis contain elevated levels of VEGF. The in vitro results confirmed the transcriptional induction of VEGF in chondrocytes after bacterial challenge by real‐time RT‐PCR, ELISA, and immunohistochemistry. This activation was mediated by a TLR‐2‐, ERK‐1/‐2‐, and AP‐1‐dependent pathway. The findings demonstrate the expression of Toll‐like receptors on mesenchymal articular chondrocytes and reveal TLR‐2‐mediated VEGF induction in human chondrocytes after Gram‐positive bacterial sensing. Since VEGF is a potent angiogenic and tissue remodelling factor, evidence that Toll‐like receptors contribute to destructive arthropathy after microbial joint infection is provided. VEGF may be a therapeutic target in the future for the prevention of post‐infectious cartilage degradation in articular joints. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Renal prothrombin mRNA is significantly decreased in a hyperoxaluric rat model of nephrolithiasis
Authors: Grover PK , Miyazawa K , Coleman M , Stahl J , Ryall RL 
Published: September 2006

AbstractAlthough urinary prothrombin fragment 1 (UPTF1) possesses several hallmarks expected of a regulatory protein in urolithiasis, its precise role remains unknown. To determine the relationship between renal prothrombin (PT), the parent molecule of UPTF1, and lithogenesis, this study quantified and compared levels of renal PT mRNA in healthy rats (n = 10) and rats rendered lithogenic (n = 10) by ingestion of 0.75% ethylene glycol for 8 weeks. Studies included morphological and histological examination of the kidneys with scanning electron microscopy of the urinary filtrates of control and experimental animals. Haematuria and calcium oxalate (CaOx) crystals occurred in the urine of all experimental rats, but not in those of controls. Histological examination showed birefringent nephroliths and associated damage in kidneys of lithogenic rats, which were not seen in the control group. The amounts of total RNA extracted from both groups of rats were similar, but the median ratio of PT to β‐actin transcript of 11.14 × 10−4(10.65 × 10−4 ± 2.24 × 10−4) in the control rats was significantly (p ≤ 0.001) reduced to 6.47 × 10−4(6.57 × 10−4 ± 2.72 × 10−4) in the lithogenic group. These results demonstrate that renal PT mRNA is reduced by ∼42% in lithogenic rats and confirm the existence of a direct association between renal PT synthesis and calculogenesis. Attempts to compare renal PT and urinary levels of PTF1 were unsuccessful because of interference from hepatic PT circulating in the blood, haematuria, and the presence of urinary CaOx crystals. This is the first report of a significant reduction in the renal expression of a urinary protein well documented to inhibit CaOx crystal growth and aggregation in undiluted human urine in vitro. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Evolution of VHL tumourigenesis in nerve root tissue
Authors: Vortmeyer AO , Tran MGB , Zeng W , Gläsker S , Riley C , Tsokos M , Ikejiri B , Merrill MJ , Raffeld M , Zhuang Z , Lonser RR , Maxwell PH , Oldfield EH 
Published: September 2006

AbstractHaemangioblastomas are the key central nervous system manifestation of von Hippel–Lindau (VHL) disease, which is caused by germline mutation of the VHL gene. We have recently shown that ‘tumour‐free’ spinal cord from patients with VHL disease contains microscopic, poorly differentiated cellular aggregates in nerve root tissue, which we descriptively designated ‘mesenchymal tumourlets’. Here we have investigated spinal cord tissue affected by multiple tumours. We show that a small subset of mesenchymal tumourlets extends beyond the nerve root to form proliferative VHL‐deficient mesenchyme and frank haemangioblastoma. We thus demonstrate that tumourlets present potential, but true precursor material for haemangioblastoma. We further show that intraradicular tumourlets consist of scattered VHL‐deficient cells with activation of HIF‐2α and HIF‐dependent target proteins including CAIX and VEGF, and are associated with an extensive angiogenic response. In contrast, activation of HIF‐1α was only observed in the later stages of tumour progression. In addition, ultrastructural examination reveals gradual transition from poorly differentiated VHL‐deficient cells into vacuolated cells with a ‘stromal’ cell phenotype. The evolution of frank haemangioblastoma seems to involve multiple steps from a large pool of precursor lesions. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
C/EBPbeta is over‐expressed in gastric carcinogenesis and is associated with COX‐2 expression
Authors: Regalo G , Canedo P , Suriano G , Resende C , Campos ML , Oliveira MJ , Figueiredo C , Rodrigues‐Pereira P , Blin N , Seruca R , Carneiro F , Machado JC 
Published: September 2006

AbstractThe CCAAT/enhancer‐binding protein beta (C/EBPbeta) transcription factor has been associated with several cancer models. In this study, the expression of C/EBPbeta was analysed in a series of 90 gastric carcinomas (GCs). We also assessed the effect of C/EBPbeta on COX‐2 expression. In normal gastric mucosa, C/EBPbeta expression was restricted to cells in the proliferative zone. In intestinal metaplasia, dysplasia, and GC of the intestinal and atypical subtypes, C/EBPbeta was over‐expressed (p < 0.0001, for the association with histological type). C/EBPbeta and Ki67, a marker of cell proliferation, were also co‐expressed in primary GC. We also observed an overlap between C/EBPbeta and COX‐2 expression in GC. Using GC cell lines we show that C/EBPbeta can regulate the expression of endogenous COX‐2 and transactivate the promoter of the COX‐2 gene, depending on its methylation status. These results suggest that C/EBPbeta may be a marker of neoplastic transformation and also play an active role in gastric tumourigenesis by regulating COX‐2 expression. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.