bluuebunny/crossref_metadata_2025 huggingface dataset:
High Mechanical Performance Composite Conductor: Multi‐Walled Carbon Nanotube Sheet/Bismaleimide Nanocomposites
Authors: Cheng Qunfeng , Bao Jianwen , Park JinGyu , Liang Zhiyong , Zhang Chuck , Wang Ben
Published: August 2009

Multi‐walled carbon nanotube (MWNT)‐sheet‐reinforced bismaleimide (BMI) resin nanocomposites with high concentrations (∼60 wt%) of aligned MWNTs are successfully fabricated. Applying simple mechanical stretching and prepregging (pre‐resin impregnation) processes on initially randomly dispersed, commercially available sheets of millimeter‐long MWNTs leads to substantial alignment enhancement, good dispersion, and high packing density of nanotubes in the resultant nanocomposites. The tensile strength and Young's modulus of the nanocomposites reaches 2 088 MPa and 169 GPa, respectively, which are very high experimental results and comparable to the state‐of‐the‐art unidirectional IM7 carbon‐fiber‐reinforced composites for high‐performance structural applications. The nanocomposites demonstrate unprecedentedly high electrical conductivity of 5 500 S cm−1 along the alignment direction. Such unique integration of high mechanical properties and electrical conductance opens the door for developing polymeric composite conductors and eventually structural composites with multifunctionalities. New fracture morphology and failure modes due to self‐assembly and spreading of MWNT bundles are also observed.
Biodegradable Polymer Crosslinker: Independent Control of Stiffness, Toughness, and Hydrogel Degradation Rate
Authors: Cha Chaenyung , Kohman Richie H. , Kong Hyunjoon
Published: August 2009

Hydrogels are being increasingly studied for use in various biomedical applications including drug delivery and tissue engineering. The successful use of a hydrogel in these applications greatly relies on a refined control of the mechanical properties including stiffness, toughness, and the degradation rate. However, it is still challenging to control the hydrogel properties in an independent manner due to the interdependency between hydrogel properties. Here it is hypothesized that a biodegradable polymeric crosslinker would allow for decoupling of the dependency between the properties of various hydrogel materials. This hypothesis is examined using oxidized methacrylic alginate (OMA). The OMA is synthesized by partially oxidizing alginate to generate hydrolytically labile units and conjugating methacrylic groups. It is used to crosslink poly(ethylene glycol) methacrylate and poly(N‐hydroxymethyl acrylamide) to form three‐dimensional hydrogel systems. OMA significantly improves rigidity and toughness of both hydrogels as compared with a small molecule crosslinker, and also controls the degradation rate of hydrogels depending on the oxidation degree, without altering their initial mechanical properties. The protein‐release rate from a hydrogel and subsequent angiogenesis in vivo are thus regulated with the chemical structure of OMA. Overall, the results of this study suggests that the use of OMA as a crosslinker will allow the implantation of a hydrogel in tissue subject to an external mechanical loading with a desired protein‐release profile. The OMA synthesized in this study will be, therefore, highly useful to independently control the mechanical properties and degradation rate of a wide array of hydrogels.
Organic Nonvolatile Memory Devices Based on Ferroelectricity
Authors: Naber Ronald C. G. , Asadi Kamal , Blom Paul W. M. , de Leeuw Dago M. , de Boer Bert
Published: August 2009

A memory functionality is a prerequisite for many applications of electronic devices. Organic nonvolatile memory devices based on ferroelectricity are a promising approach toward the development of a low‐cost memory technology. In this Review Article we discuss the latest developments in this area with a focus on three of the most important device concepts: ferroelectric capacitors, field‐effect transistors, and diodes. Integration of these devices into larger memory arrays is also discussed.
Towards Optimization of Materials for Dye‐Sensitized Solar Cells
Authors: Luo Yanhong , Li Dongmei , Meng Qingbo
Published: August 2009

Dye‐sensitized solar cells (DSCs) have received widespread attention owing to their low cost, easy fabrication, and relatively high solar‐to‐electricity conversion efficiency. Based on the nanocrystalline TiO2 electrode, Ru‐polypyridyl‐complex dye, liquid electrolyte with I−/I3− redox couple, and Pt counter electrode, DSCs have already exhibited an efficiency above 11% and offer an appealing alternative to conventional solar cells. However, further improvements in the efficiency and stability are still required to drive forward practical application. These improvements require the cooperative optimization of the component materials, structures, and processing techniques. In this Research News article, recent progress in DSCs made by our group are reviewed, including some novel approaches to the synthesis of solid‐state and environmentally friendly electrolytes, the fabrication of alternative low‐cost nanostructural electrodes, and the control of recombination at the interfaces.
Deagglomeration of nanoparticle aggregates via rapid expansion of supercritical or high‐pressure suspensions
Authors: To Daniel , Dave Rajesh , Yin Xiaolong , Sundaresan Sankaran
Published: August 2009

Deagglomeration of suspensions of alumina and titania nanopowders (i.e., nanoparticle aggregates) via rapid expansion of supercritical suspensions (RESS) or high‐pressure suspensions (REHPS) was studied. The size distribution of fragmented nanopowders was characterized by online Scanning Mobility Particle Spectrometer (SMPS) and Aerodynamic Particle Sizer (APS), and by offline Scanning Electron Microscopy (SEM). SMPS and SEM measurements indicate that the average agglomerate sizes were well below 1 μm, consistent with the length scales observed in our complementary RESS/REHPS mixing experiments using alumina and silica nanopowders. The APS measurements, on the other hand, were affected by reagglomeration during sampling and yielded an agglomerate size range of 1 to 3 μm. Analysis of the RESS/REHPS process through compressible flow models revealed that both the shear stress in the nozzle and the subsequent impact of the agglomerates with the Mach disc in the free expansion region can lead to micron or sub‐micron level deagglomeration. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Are cortisol profiles a stable trait during child development?
Authors: Flinn Mark V.
Published: August 2009

Exposure to stressful experiences can increase vulnerability to adverse health outcomes. A potential neuroendocrine mechanism mediating the link between stress and health is the hypothalamic‐pituitary‐adrenal (HPA) system, with a key role attributed to the glucocorticoid hormone cortisol. Retrospective and cross sectional clinical studies of humans and experimental studies with nonhuman primates and rodents suggest that traumatic experiences during critical periods in development may have permanent effects on HPA regulation, which in turn can have deleterious effects on health. Here I report results from a continuous 20‐year study (1988–2009) of children in a rural community on Dominica. Sequential data on cortisol levels, social stressors, and health in naturalistic, everyday conditions are examined to assess developmental trajectories of HPA functioning. Saliva aliquots were assayed for cortisol in concert with monitoring of growth, morbidity, and social environment. Analyses here include data from 1989 to 1999 for 147 children aged 3–16 years with >100 saliva samples each. Cortisol values were standardized by elapsed time since wake‐up. Results do not support the hypothesis that traumatic stress during childhood causes permanent general elevation of cortisol levels. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Breastfeeding as obesity prevention in the United States: A sibling difference model
Authors: Metzger Molly W. , McDade Thomas W.
Published: August 2009

In light of the growing prevalence of obesity in the United States, and the health risks associated with childhood obesity in particular, it is critical to identify avenues for obesity prevention. This study tests the hypothesis that breastfeeding serves as one protective factor against children's subsequent development of obesity. We used linear‐, logistic‐, and sibling fixed‐effects regression models to evaluate the association between infant feeding history and body mass index (BMI) in late childhood or adolescence (9–19 years, mean = 14 years). Complete data were available for 976 participants (488 sibling pairs) in the 2002 Child Development Supplement of the Panel Study of Income Dynamics, a nationally representative survey of families in the United States. In sibling pairs in which only one sibling was breastfed, the breastfed sibling had an adolescent BMI that was 0.39 standard deviations lower than his or her sibling, controlling for child‐specific factors that may have influenced parents' feeding decisions. This effect is equivalent to a difference of more than 13 pounds for a 14‐year‐old child of average height. Furthermore, fixed‐effects logistic regressions predicting overweight and obese status showed that breastfed siblings were less likely to reach those BMI thresholds. We therefore conclude that breastfeeding in infancy may be an important protective factor against the development of obesity in the United States. The application of a sibling fixed‐effects model provides stronger evidence of a causal relationship than prior research reporting similar patterns of association. Am. J. Hum. Biol. 2010. © 2009 Wiley‐Liss, Inc.
PER2 variantion is associated with depression vulnerability
Authors: Lavebratt Catharina , Sjöholm Louise K. , Partonen Timo , Schalling Martin , Forsell Yvonne
Published: August 2009

The circadian clock is driven by transcription–translation feedback loops and regulates rhythms that approximate the 24‐hr day–night cycle or light–dark transitions. Disruptions of the circadian rhythms are common in depressed patients, expressed for example as sleep disturbances. Genetic variations in core circadian genes may in part explain these abnormalities. To investigate whether genetic variation in core circadian genes associates with vulnerability to depression, we genotyped 18 genes in a Swedish population based sample. Genetic variations indicative of association with depression, or with winter depression in our previous study, were tested for association to depression in a second Swedish depression‐control sample set. PER2 genetic variation was associated with depression vulnerability, and this genetic risk did not seem to require exposure to potential sleep disturbance factors such as negative life event or financial strain that are known to increase the risk for depression. Polymorphisms in the circadian genes NPAS2, ARNTL, and RORA were also suggested to contribute to depression vulnerability. The findings we report for PER2, ARNTL, and RORA are supported by at least two of the three sample sets. In conclusion, genetic variation in PER2 is associated with depression vulnerability a Swedish population‐based sample. More studies are needed to determine if this is the case also for NPAS2, ARNTL, and RORA. © 2009 Wiley‐Liss, Inc.
State estimation of a solid‐state polymerization reactor for PET based on improved SR‐UKF
Authors: Liu Ji , Gu Xing Sheng
Published: August 2009

A state estimator for the continuous solid‐state polymerization (SSP) reactor of polyethylene terephthalate (PET) is designed in this study. Because of its invalidity in the application to some of the practical examples such as SSP processes, the square‐root unscented Kalman filter (SR‐UKF) algorithm is improved for the state estimation of arbitrary nonlinear systems with linear measurements. Discussions are given on how to avoid the filter invalidation and accumulating additional error. Orthogonal collocation method has been used to spatially discretize the reactor model described by nonlinear partial differential equations. The reactant concentrations on chosen collocation points are reconstructed from the outlet measurements corrupted with a large noise. Furthermore, the error performance of the developed ISR‐UKF is investigated under the influence of various initial parameters, inaccurate measurement noise parameters and model mismatch. Simulation results show that this technique can produce fast convergence and good approximations for the state estimation of SSP reactor. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Modeling of polycyclic aromatic hydrocarbon SLE in aromatic solvents
Authors: Muthukumarasamy Thenmozhi , Thiruganam Karunanithi
Published: August 2009

Equilibrium solubilities of polycyclic aromatic hydrocarbon (PAH) solutes naphthalene, fluorene, acenaphthalene, fluoranthene, anthracene, phenanthrene, pyrene, chrysene and triphenylene in benzene and substituted benzene solvents are predicted using the Dortmund‐AU model. The Dortmund‐AU method performs better than the UNIFAC and modified UNIFAC (Dortmund) models when applied to PAH in benzene systems, but the accuracy of predictions deteriorates in the case of PAHs that have melting points greater than 380 K. Accounting for the heat capacity change on melting term makes considerable difference to the ideal solubility calculation in the case of higher‐melting PAHs. A new term is added to the residual part of activity coefficient in the UNIFAC model to derive a modified empirical version. Application of this model to PAH solid–liquid equilibria is verified and the results are compared with those of Dortmund‐AU model. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
In‐situ catalytic synthesis of ammonia from urea in a semi‐batch reactor for safe utilization in thermal power plant
Authors: Sahu J. N. , Patwardhan A. V. , Meikap B. C.
Published: August 2009

Urea as the source of ammonia for the flue gas conditioning/NOx reduction system in thermal power plant has the obvious advantages that no ammonia shipping, handling and storage is required. The process of this invention minimizes the risks and hazards associated with the transport, storage and use of anhydrous and aqueous ammonia, as ammonia is a highly volatile noxious material. But no such rapid urea conversion process is available as per requirement of high conversion in shorter time, so here we study the catalytic hydrolysis of urea for fast conversion in a semi‐batch reactor. The catalysts used in this study are: TiO2, fly ash, mixture of Ni and Fe and Al2O3. Number of experiments was carried out in a semi‐batch reactor at different catalyst doses, temperatures and concentration of urea solution from 10 to 30% by weight and equilibrium study has been made. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Synthesis of mesoporous alumina–titania membranes by the sol‐gel method
Authors: Bottino A. , Comite A. , Capannelli G.
Published: August 2009

Ceramic tubular membranes with alumina–titania top layers were prepared using the dipping procedure and a mixed sol composed of both boehmite and titania. The influence of the Ti/Al ratio, the amount of an organic additive (namely hydroxypropylcellulose), the dip‐time, the number of depositions and drying–calcination conditions on the membrane morphology and transport properties were investigated. The conditions for the formation of a defect‐free and homogeneous top layer were individuated. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Evaluation of porous catalytic membranes operated in pore‐flow‐through mode for hydrogenation of α‐methylstyrene
Authors: Urbanczyk Daniel , Dittmeyer Roland , Wolf Aurel , Warsitz Rafael , Fischer Gundula , Voigt Ingolf
Published: August 2009

A study of the catalytic membrane contactor operated in pore‐flow‐through (PFT) mode was carried out for hydrogenation of α‐methylstyrene (AMS) to cumene over palladium as a test reaction. By applying a metalorganic chemical vapour deposition method, the catalyst was deposited as nanoparticles on the pore walls of porous alumina capillaries. Experiments were performed with up to six individual Pd‐activated capillaries in a laboratory‐scale reactor set‐up and with capillary bundles in a small pilot plant. The influence of the operating parameters on the reactor performance such as temperature (303–333 K), hydrogen pressure (5–10 bar), transmembrane flux (up to 200 l·m−2·min−1), pore size of the capillaries (0.6–3.0 µm) and concentration of AMS in n‐heptane used as solvent was investigated. Moreover, the performance of the PFT‐system was compared to that of conventional reactors (e.g. fixed bed, trickle bed, bubble column, stirred tank) and novel reactor designs (catalytic membrane contactor in diffuser mode, monolith reactor) based on published data. It is shown that the PFT principle enables very high activity, comparable with a suspended powder catalyst in a stirred tank reactor and, at the same time, an excellent space time yield. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Estimating limit conversion for methane steam reforming in a palladium membrane reactor using countercurrent sweep gas
Authors: Hara S. , Haraya K. , Barbieri G. , Drioli E.
Published: August 2009

Generally speaking, conversion increases with increasing reactor length to approach a certain value: so‐called limit conversion. Limit conversion for a membrane reactor with a cocurrent sweep gas has been studied extensively. However, characteristics of limit conversion for the countercurrent, which are examined in this study, remain unclear. First, conversions of MRs with different reactor lengths were calculated using a conventional mode of integrating differential equations. Results confirmed that limit conversion is not always 100%, even for the countercurrent. Long MRs were found to have a pseudo‐constant state inside, characterized by an extremely low apparent reaction rate and permeation rate. Secondly, a novel approach to estimate limit conversion was developed: reaction equilibrium constants and hydrogen partial pressure balance between both sides were applied not for the end of the reactor but for the pseudo‐constant state. This new approach suggests that limit conversion for the countercurrent depends on the reaction temperature, feed‐side and permeation‐side pressures, feed‐gas composition, and the sweep rate. It is fundamentally independent of reaction kinetic equations and hydrogen permeation‐rate properties. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Studies on binary copolymerization and glass transition temperatures of methyl methacrylate with ethyl methacrylate and n‐butyl methacrylate
Authors: Liu Guodong , Zhang Liying , Wang Yanli , Zhao Peng
Published: August 2009

In this article, bulk copolymerization of methyl methacrylate (MMA) with ethyl methacrylate (EMA) and n‐butyl methacrylate (n‐BMA) was carried out at 60°C. The monomer reactivity ratios obtained by nonlinear fitting with Mayo‐Lewis equation were as follows: rMMA = 0.93 ± 0.03, rEMA = 0.96 ± 0.03 for the MMA/EMA, and rMMA = 0.99 ± 0.05, rn‐BMA = 1.11 ± 0.06 for the MMA/n‐BMA series. A new equation proposed in view of bond rotation flexibility (Liu et al., J Phys Chem B 2008, 112, 93), which contains mole fractions of triads and Tg's of corresponding periodic copolymers, was applied to describe the relation of Tg's of MMA‐EMA, MMA‐n‐BMA copolymers with their compositions and sequence distribution. Excellent fitting results were obtained and Tg values of the assumed periodic copolymers were predicted by fitting the random copolymers. The influence of the substituent volume as well as substituent density on the Tg of poly(methyl methacrylate) (PMMA) was also tentatively predicted. © 2009 Wiley Periodicals, Inc. J Appl Polym, 2009
Viscoelastic properties and characterization of inorganic particulate‐filled polymer composites
Authors: Liang J. Z.
Published: August 2009

To identify effects of glass bead (GB) content on the dynamic mechanical properties of filled low‐density‐polyethylene (LDPE) composites, the storage modulus, loss modulus, glass transition temperature, and mechanical damping of these composites were measured using a Du Pont dynamical mechanical analysis instrument in temperature range from −150 to 100°C. It was found that the storage modulus increased nonlinearly with an increase of the GB volume fraction. On the basis of Eshelby's method and Mori's work, an equation describing the relationship between the relative storage modulus (E′R) and filler volume fraction for polymeric composites was proposed, and the E′R of LDPE/GB composites were estimated by means of this equation at temperatures of −25, 0, and 25°C, and the calculations were compared with the experimental data, good agreement was showed between the predictions and the measured data. Furthermore, this equation was verified by the experimental from Al(OH)3 filled EPDM composites at glassy state reported in a reference. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Dynamic mechanical, thermal, and morphological properties of silane‐treated montmorillonite reinforced polycarbonate nanocomposites
Authors: Chow W. S. , Neoh S. S.
Published: August 2009

Three different loading of 3‐aminopropyltriethoxysilane (APS) was used to modify the Na‐montmorillonite via cation exchange technique. The Na‐MMT and silane‐treated montmorillonite (STMMT) were melt‐compounded with polycarbonate (PC) by using Haake Minilab machine. The PC nanocomposite samples were prepared by using Haake Minijet injection molding technique. The intercalation and exfoliation of the PC/MMT nanocomposites were characterized by using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal properties of the PC nanocomposites were investigated by using dynamic mechanical analyzer and thermogravimetry analyzer. XRD and TEM results revealed partial intercalation and exfoliation of STMMT in PC matrix. Increase of APS concentration significantly enhanced the storage modulus (E′) and improved the thermal stability of PC nanocomposites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of soluble poly(ether imide)s containing fluorenyl cardo groups
Authors: An Hao‐Yuan , Zhan Mao‐Sheng , Wang Kai
Published: August 2009

Two series of poly(ether imide)s (PEIs) containing fluorenyl cardo groups in the main chains were synthesized, which are derived from the polycondensation of 9,9′‐bis(4‐aminophenoxyphenyl)fluorene (BAOFL) or 9,9′‐bis(3‐trifluoromethyl,4‐aminophenoxyphenyl)fluorene (6F‐BAOFL) with four kinds of dianhydrides (3,3′,4,4′‐biphenyltetracarboxylic dianhydride, 4,4′‐oxydiphthalicanhydride, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride, and bisphenol‐A dianhydride), respectively. The PEI films and PEI powder were prepared by thermal and chemical imidization, respectively. The PEIs were characterized by FTIR, 1H‐NMR, differential scanning calorimetry, thermogravimetric analysis, and UV–vis were performed on inherent viscosity, solubility, and tensile tests. The effects of fluorenyl cardo groups and ether linkages on the solubility, tensile properties, thermal stability, and optical properties were investigated in detail. It was found that the PEIs had good solubility in common organic solvents and good optical transparency in visible light region. In addition, the PEI films exhibited excellent tensile and thermal properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of Co and V complexes on polymerization of methyl methacrylate initiated by AlEt2Br‐TEMPO catalyst
Authors: Ravikumar Lingam , Thevi Raju
Published: August 2009

2,2,6,6‐Tetramethyl piperidinoxy (TEMPO) activated with diethyl aluminum bromide was employed as an initiator system for methyl methacrylate polymerization. Effect of addition of Co(acac)3 and VO(acac)2 complexes to the initiators system on methyl methacrylate polymerization were studied in benzene solvent. Various reaction parameters such as Al/TEMPO, monomer concentration, reaction temperature and time applied to the polymerization were investigated. The polymer yields, molecular weight and molecular weight distributions can be controlled with the addition of Co(acac)3 to the initiator system. PMMA's of molecular weight distributions, as low as 1.10 was obtained under relatively mild conditions, in the temperature range 40–60°C in benzene solvent. However, Co and V complexes did not influence the micro structure of the PMMA's formed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Molecularly imprinted polyethersulfone microfibers for the binding and recognition of bisphenol A
Authors: Wang Dongsheng , Wei Qiang , Zhang Yijia , Zhao Changsheng
Published: August 2009

Bisphenol A (BPA)‐imprinted polyethersulfone (PES) microfibers for the recognition of BPA were prepared by means of wet‐spinning method based on the liquid–liquid phase separation technique. Two kinds of the BPA‐imprinted microfibers were fabricated with the diameters of about 85 μm and 265 μm, respectively. Extraction of BPA from the microfibers was carried out by immersing the imprinted microfibers into ethanol. In the recognition experiments, the binding amounts were about 24.0, 43.0, and 70.0 μmol/g for the nonimprinted microfibers, whereas those were about 50.0, 87.0, 120.0 μmol/g for the imprinted PES microfibers with the diameter of about 85 μm in 100, 200, and 400 μM BPA solution, respectively. Both of the binding amounts and the adsorption rate for the imprinted microfibers with smaller diameter were higher than that for the microfibers with larger diameters. The selectivity results indicated that the BPA‐imprinted microfibers showed higher recognition coefficient (α) for BPA than phenol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Syntheses of PAM microgel surfacely covered with alkyl quaternary ammonium surfactant/Keggin‐type polyoxometalate complexes
Authors: Zhou Tong , Li Hong , Liu Guoyu , Zhang Long , Yao Dongdong , Hu Daodao
Published: August 2009

The composite microspheres of poly(lacrylamide) microgels (PAM) surfacely covered with [2‐(methacryloyloxy)ethyl]dodecyldimethylammonium (MEDDAB)‐tungstophosphate (HPW) complexes (MEDDAB‐HPW) were synthesized by using ion‐exchange reaction between MEDDAB located within the porous PAM microgels and HPW in aqueous solution. The morphology and component of the composite microspheres were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis, respectively. The results indicated that PAM/MEDDAB‐HPW composite microsphere with different hierarchical surface structures could be obtained by controlling the weight ratio of MEDDAB to HPW in the microgels and cross‐linking degree of PAM microgels. Although the surface morphologies of the composite microspheres prepared in different conditions were different, a general feature was that the composite microspheres have the core‐shell structure and the wrinkly surface covered with the particles of MEDDAB‐HPW complexes. The formation of the wrinkly surface is attributed to the difference in shrinkage between inside and outside of PAM microgel frameworks due to deposition of MEDDAB‐HPW on the surface, and the formation of MEDDAB‐HPW small particles originates from the reaction between MEDDAB aggregation and HPW. For this composite microsphere, PAM hydrogel core is suitable to store water‐soluble substances, and the shell composed of the surfactant/Keggin‐type polyoxometalate complexes is not only amphiphilic but also catalytic. Additionally, PAM/MEDDAB‐HPW composite microspheres with big size and MEDDAB‐HPW particles with small size make the composite microspheres not only easy for separation but also beneficial for catalysis. This material provides an example to construct microreactors with new structure used in diphase catalytic reaction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Relationship between polarity of template hydrogel and nanoporous structure replicated in sol–gel‐derived silica matrix
Authors: Kurumada K. , Suzuki A. , Baba S. , Otsuka E.
Published: August 2009

We replicated the nanoscopic network structure of acrylamide series hydrogels in silica matrix. In the replication, the mutual affinity of the template polymeric species to sol–gel‐derived silica matrix significantly affects the replicated porous structure formed in the silica matrix. In this work, we intended to fabricate nanoscopic replicas of hydrogels of acrylamides with various hydrophobic end groups. First, the alcoxy silane, tetraethylorthosilicate (TEOS) was hydrolyzed with the template hydrogel. Subsequently, the nanoporous silica solid structure was obtained by removing the hydrogel by calcination in air at 600°C. The nanoscopic structure of those replicas was estimated by transmission electron microscopy (TEM) and nitrogen adsorption/desorption at 77 K. Basically, the nanoscopic replication was possible using the examined hydrogels of polyacrylamides. As the template hydrogel became more nonpolar, the size of the nanopores in the silica replica increased. Thus, the contrast in the polarity between the template hydrogel and silica matrix leads to the enhanced driving force for the mutual segregation or phase separation to occur. The replicated nanoporous structure is considered as a type of a transient structure arrested on the way to the completion of the phase separation of the template polymeric species from the silica matrix. Therefore, the larger contract in the polarity between the structure directing hydrogel and solid matrix lead to the formation of the larger nanopores because of the enhancement in the driving force toward the segregation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of organically modified nanoclay on the performance of pineapple leaf fiber‐reinforced polypropylene nanocomposites
Authors: Biswal Manoranjan , Mohanty Smita , Nayak Sanjay K.
Published: August 2009

Polypropylene/Pine apple leaf fiber (PP/PALF)‐reinforced nanocomposites were fabricated using melt blending technique in a twin‐screw extruder (Haake Rheocord 9000). Variation in mechanical properties, crystallization behavior, water absorption, and thermal stability with the addition of nanoclay in PP/PALF composites were investigated. It was observed that the tensile, flexural, and impact properties of PP increase with the increase in fiber loading from 10 to 30 wt %. Composites prepared using 30 wt % PALF and 5 wt % MA‐g‐PP exhibited optimum mechanical performance with an increase in tensile strength to 31%, flexural strength to 45% when compared with virgin PP. Addition of nanoclay results in a further increase in tensile and flexural strength of PP/PALF composites to 20 and 24.3%, which shows intercalated morphology. However, addition of nanoclay does not show any substantial increase in impact strength when compared with PP/PALF composites. Dynamic mechanical analysis tests revealed an increase in storage modulus (E′) and damping factor (tan δ), confirming a strong influence between the fiber/nanoclay and MA‐g‐PP. Differential scanning calorimetry, thermogravimetric analysis thermograms also showed improved thermal properties when compared with the virgin matrix. TEM micrographs also showed few layers of agglomerated clay galleries along with mixed nanomorphology in the nanocomposites. Wide angle X‐ray diffraction studies indicated an increase in d‐spacing from 22.4 Å in Cloisite 20A to 40.1 Å in PP/PALF nanocomposite because of improved intercalated morphology. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and mechanical properties of diimide‐hydrogenated natural rubber vulcanizates
Authors: Arayapranee Wanvimon , Rempel Garry L.
Published: August 2009

Hydrogenated natural rubber (HNR), providing an ethylene–propylene alternating copolymer, was prepared by the chemical modification of natural rubber latex (NRL) using diimide generated from hydrazine (N2H4) and hydrogen peroxide (H2O2), with copper sulfate (CuSO4) as catalyst. 1H‐NMR analysis indicated that 48% hydrogenation was performed with a mole ratio of N2H4/double bonds = 4 and H2O2/N2H4 = 1.5 at 50°C for 7 h. The obtained HNR was subjected to a sulfur cure by using a conventional milling process. The cure characteristics, mechanical properties before and after heat aging, and abrasion and ozone resistances of HNR vulcanizate were examined and compared with those of natural rubber (NR), ethylene propylene diene terpolymer (EPDM) and 50 : 50 NR/EPDM vulcanizates. The results indicated that the cure rate of 48% HNR showed no significant change when compare to both NR and 50 : 50 NR/EPDM blends, and offered a better processing advantage over EPDM. The mechanical properties and abrasion resistance of a 48% HNR vulcanizate were comparable to those of a NR vulcanizate. Additionally, its heat and ozone resistances were better than those of NR vulcanizate, due to a reduction in the amount of double bonds in the backbone chain. Thus, hydrogenation of NR can lead to a type of rubber that has improved heat and ozone resistances while still maintaining its good mechanical properties. Consequently, it improves the properties of NR for a wide range of applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Learning to lead: Self‐ and peer evaluation of team leaders in the human structure didactic block
Authors: Chen Laura P. , Gregory Jeremy K. , Camp Christopher L. , Juskewitch Justin E. , Pawlina Wojciech , Lachman Nirusha
Published: August 2009

Increasing emphasis on leadership in medical education has created a need for developing accurate evaluations of team leaders. Our study aimed to compare the accuracy of self‐ and peer evaluation of student leaders in the first‐year Human Structure block (integrated gross anatomy, embryology, and radiology). Forty‐nine first‐year medical students at Mayo Medical School were assigned to learning teams of three or four members. Teams worked together on daily laboratory dissection, clinical projects, embryology presentations, and daily group quizzes. Student team leaders were responsible for leading laboratory dissection, reviewing radiographic findings, and organizing group assignments. Weekly electronic surveys were administered to evaluate team leaders on altruism, compassion, respect, integrity, responsibility, commitment to excellence, and self‐reflection. Results demonstrated that team leaders rated themselves lower than their peers rated them in multiple aspects of leadership. Peer evaluation of team leaders was statistically higher than self‐evaluation in all traits measured except respect. Female leaders were rated higher by their peers in the areas of responsibility and self‐reflection compared to male leaders. This study demonstrates the need for increased communication between team leaders and members, along with creation of a mutually respectful environment, to improve leader awareness of their abilities and foster team success. Anat Sci Educ 2:210–217, 2009. © 2009 American Association of Anatomists.
Regulation of GCL activity and cellular glutathione through inhibition of ERK phosphorylation
Authors: Chen Zhi‐Hua , Saito Yoshiro , Yoshida Yasukazu , Niki Etsuo , Noguchi Noriko
Published: August 2009

Extracellular signal‐regulated protein kinase (ERK), one of the mitogen‐activated protein kinase, has been known to be involved in diverse cellular functions. In this work, we found that basically inhibition of this kinase in cultured cells markedly increased the γ‐glutamate‐cysteine ligase (GCL; EC 6.3.2.2) activity, but without any considerable induction of the GCL genes. The increased GCL activity consequently elevated the cellular GSH level and eventually enhanced the cellular antioxidant capacity. Genetic inhibition of B‐Raf, the upstream of ERK, also resulted in increased GCL activity and GSH level. Recent evidence also suggests that chronic pro‐oxidant exposure results in the loss of ERK phosphorylation in vivo. Therefore, the findings in the present study suggest that inhibition of B‐Raf/MEK/ERK pathway might be a promising physiological approach to up‐regulate GCL activity and GSH. This study would also help us to understand the comprehensive role of the Raf/MEK/ERK pathway in overall physio/pathological conditions.
Effect of quercetin on oxidative nuclear and mitochondrial DNA damage
Authors: Potenza Lucia , Calcabrini Cinzia , De Bellis Roberta , Mancini Umberto , Cucchiarini Luigi , Dachà Marina
Published: August 2009

Quercetin is a well‐investigated antioxidant known to protect cells against oxidative nuclear DNA damage. There is no knowledge regarding its effect on oxidative mitochondrial DNA damage. In this study we investigated the effect of quercetin on oxidatively‐injured DNA. Cell‐free and cell studies were performed. Cell‐free analyses carried out on plasmidic DNA showed that quercetin protects from all oxidative challenges used. Cellular studies were carried out on NCTC 2544 cells which were insulted with hydrogen peroxide and UVC radiations. Nuclear and mitochondrial DNAs were analysed by measuring DNA damage with a quantitative polymerase chain reaction. Quercetin supplementation showed significant genoprotective activity on mitochondrial DNA when hydroperoxide was used. The evidence of the protection afforded by quercetin suggests that this flavonoid may play an important role on mitochondrial genome stability.
Inhibition of cellular invasive parameters in influenza A virus‐infected MDCK and vero cells by a nutrient mixture
Authors: Roomi M.W. , Jariwalla R.J. , Kalinovsky T. , Roomi N. , Niedzwiecki A. , Rath M.
Published: August 2009

Influenza, a long‐standing common infection, poses a serious health problem causing significant morbidity and mortality, and imposing substantial economic costs. To date there are no effective antiviral therapies. A unique nutrient mixture (NM), containing lysine, proline, ascorbic acid, green tea extract, N‐acetyl cysteine and selenium among other micro nutrients, has been shown to exert a wide range of biochemical and pharmacological effects, among them anti‐carcinogenic and anti‐atherogenic activity both in vitro and in vivo. In a previous study, NM was found to significantly inhibit influenza virus A associated neuraminidase enzyme as well as production of NP antigen in a dose‐dependent manner. Influenza virus A not only infects pulmonary areas, but also manifests in extrapulmonary areas, which require basement membrane disruption by matrix metalloproteinases capable of degrading collagen type IV. This prompted us to study the effect of NM on cellular invasive parameters of virus‐infected and non‐infected MDCK and Vero cells. NM inhibited extracellular invasive parameters such as MMP‐2 and MMP‐9 secretion and Matrigel invasion. Results indicated that the relatively non‐toxic nutrient mixture tested in this investigation has potential in influenza treatment by not only decreasing viral multiplication in infected cells but also by blocking the enzymatic degradation of the extracellular matrix.
Expression of ß‐carotene 15,15′‐monooxygenase gene and retinol status in type 2 diabetic Goto‐kakizaki rats
Authors: Takitani Kimitaka , Miyazaki Hiroshi , Takaya Ryuzo , Tamai Hiroshi
Published: August 2009

The vitamin A status has been studied in type 2 diabetes and it is known that plasma retinol levels of patients with type 2 diabetes are elevated. However, the details of vitamin A metabolism in type 2 diabetes are unclear. ß‐Carotene exhibits biological activity as provitamin A and ß‐carotene 15,15′‐monooxygenase (BCM) cleaves ß‐carotene to form retinal. We studied BCM gene expression in type 2 diabetic Goto‐Kakizaki (GK) rats.

BCM gene expression was analyzed in the liver, intestine, and testis of 8‐ and 13‐week‐old GK rats and Wistar rats (control). The plasma and liver retinol levels were measured, and plasma retinol‐binding protein (RBP) was detected. BCM gene expression in the liver, intestine and testis of GK rats was increased compared with that in controls. Plasma retinol levels and RBP levels were increased in GK rats, but hepatic retinol levels did not differ between GK rats and controls. BCM gene expression in the liver and intestine might affect retinol levels in type 2 diabetes. Conversion of ß‐carotene to retinal might be accelerated in the presence of insulin resistance status, so that plasma retinol levels are increased in type 2 diabetes.
Effects of a nutrient mixture on infectious properties of the highly pathogenic strain of avian influenza virus A/H5N1
Authors: Deryabin Petr G. , Lvov Dmitry K. , Botikov Andrey G. , Ivanov Vadim , Kalinovsky Tatiana , Rath Matthias , Niedzwiecki Aleksandra
Published: August 2009

Numerous outbreaks of avian influenza virus infection (A/H5N1) have occurred recently, infecting domestic birds, chicken and ducks. The possibility of the emergence of a new strain of influenza virus capable of causing a pandemic in humans is high and no vaccine effective against such a strain currently exists. A unique nutrient mixture (NM), containing lysine, proline, ascorbic acid, green tea extract, N‐acetyl cysteine, selenium among other micro nutrients, has been shown to exert a wide range of biochemical and pharmacological effects, including an inhibitory effect on replication of influenza virus and HIV. This prompted us to investigate the potential anti‐viral activity of a nutrient mixture (NM) and its components on avian influenza virus A/H5N1at viral dosages of 1.0, 0.1 and 0.01 TCID50. Antiviral activity was studied in cultured cell lines PK, BHK‐21, and Vero‐E6. Virus lysing activity was determined by co‐incubation of virus A/H5N1 with NM for 0–60 min, followed residual virulence titration in cultured SPEV or BHK‐21 cells. NM demonstrated high antiviral activity evident even at prolonged periods after infection. NM antiviral properties were comparable to those of conventional drugs (amantadine and oseltamivir); however, NM had the advantage of affecting viral replication at the late stages of the infection process.
Insulin like growth factor‐1 and insulin like growth factor binding proteins in the cerebrospinal fluid and serum from patients with Alzheimer's disease
Authors: Salehi Zivar , Mashayekhi Farhad , Naji Mohammad
Published: August 2009

Insulin like growth factor‐1 (IGF‐1) is ubiquitously expressed growth factor that has profound effects on the growth and differentiation of many cell types and tissues, including cells of the central nervous system (CNS). IGF‐1 is produced by a wide variety of cells and is found in many biological fluids including cerebrospinal fluid (CSF). IGF‐1 plays important role during CNS development and repair. IGF‐1 has broad range neuroprotective effects and is a therapeutic candidate for Huntington's disease (HD). IGF‐1 protects striatal neurons from the toxicity of mutated Huntington in vitro and improves neuronal survival in vivo in a phenotypic model of HD. Alzheimer's disease (AD) is an age‐dependent dementia characterized by progressive loss of cognitive functions and by characteristic pathological changes in the brain: the formation of aggregates extracellularly by ß‐amyloid (AB) peptide and intracellularly by tau proteins. Since cerebrospinal fluid (CSF) is in contact with the extracellular space of the brain, biochemical brain modifications could be reflected in the CSF. IGFs in circulation and other physiological fluids are associated with a group of high‐affinity binding proteins insulin like growth factor binding proteins (IGFBPs) that specifically bind and modulate their bioactivity at the cellular level. The aim of this study was to determine the level of CSF and serum IGF‐1 and IGFBPs concentrations in the patients with AD. CSF was obtained by lumbar puncture. The presence of IGF‐1 and IGFBPs in the CSF and serum samples was confirmed by Western blot using anti‐IGF‐1 and IGFBPs antibodies. Using enzyme linked immunosorbent assay (ELISA), it was shown that the concentration of CSF and serum IGF‐1 and IGFBPs in the patients with AD is higher than in normal control. The data from this study indicate that IGF‐1 is a constant component of human CSF. It is also concluded that high levels of CSF IGF‐1 may be partly related to AD pathophysiology.
Withaferin A induces apoptosis and inhibits adipogenesis in 3T3‐L1 adipocytes
Authors: Park Hea Jin , Rayalam Srujana , Della‐Fera Mary Anne , Ambati Suresh , Yang Jeong‐Yeh , Baile Clifton A.
Published: August 2009

Withaferin A (WA), a highly oxygenated steroidal lactone that is found in the medicinal plant Withania somnifera (also called ashwagandha) has been reported to have anti‐tumor, anti‐angiogenesis, and pro‐apoptotic activity. We investigated the effects of WA on viability, apoptosis and adipogenesis in 3T3‐L1 adipocytes. Pre‐ and post‐confluent preadipocytes and mature adipocytes were treated with WA (1–25 μM) up to 24 hrs. Viability and apoptosis were measured by CellTiter‐Blue® Cell Viability Assay and single strand DNA ELISA Assay, respectively. WA decreased viability and induced apoptosis in all stages of cells. Induction of apoptosis by WA in mature adipocytes was mediated by increased ERK1/2 phosphorylation and altered Bax and Bcl2 protein expression. The effect of WA on adipogenesis was examined by Adipo Red Assay after treating with WA (0.1–1 μM) during the differentiation period. WA decreased lipid accumulation in a dose‐dependent manner and decreased the expression of peroxisome proliferator‐activated receptor γ, CCAAT/enhancer binding protein α and adipocyte fatty acid binding protein. The effects on apoptosis and lipid accumulation were also confirmed with Hoechst staining and Oil Red O staining, respectively. These results show that WA acts on adipocytes to reduce cell viability and adipogenesis and also induce apoptosis.
Effect of mono‐(2‐ethylhexyl) phthalate (MEHP) on resumption of meiosis, in vitro maturation and embryo development of immature mouse oocytes
Authors: Dalman A. , Eimani H. , Ashtiani S.K. , Valojerdi M.R. , Eftekhari‐Yazdi P. , Shahverdi A. , Sepehri H.
Published: August 2009

The purpose of this study was to evaluate the effect of MEHP on in vitro maturation of mouse oocytes and resulting embryo development.

Denuded oocytes (DO) were cultured in maturation medium supplemented with 0, 50, 100,200 and 400 μM levels of MEHP for 24 h. The matured oocytes then were fertilized and cultured for 4 days.

The percentage of Germinal Vesicle (GV) stage oocytes were significantly higher in 200 and 400 μM MEHP treatment comparing to the control (P < 0.05). The proportion of oocytes that progressed to the metaphase II (MII) stage was significantly decreased by adding of MEHP in a dose related pattern. The 2‐cell embryo formation was significantly decreased with 400 μM treatments than the control. Moreover with further culture in experimental groups none of the embryos comparing to that of the control group were developed to morulla stage (P < 0.05).

These results indicate that MEHP could negatively modulate mouse oocyte meiotic maturation in vitro and embryo development, suggesting possible risks for human and other mammalians reproductive health.
Bilberry inhibits angiogenesis in chick chorioallontoic membrane
Authors: Ozgurtas Taner , Aydin Ibrahim , Tapan Serkan , Avci Ozgur , Erbil M. Kemal
Published: August 2009

Angiogenesis is the process of generating new blood vessels from preexisting vessels and is considered essential in many pathological conditions. Bilberry has been traditionally used as a folk medicine for some countries. The purpose of the present study was to evaluate the effect of bilberry in chick chorioallantoic membrane angiogenesis modelin vivo.In this well characterized model, bilberry inhibited angiogenesis in a concentration‐dependent manner. Compared with the normal group, bilberry group has significant decreased vessels proliferation. These results provide evidence that bilberry inhibits angiogenesis and may be useful for treating angiogenesis‐dependent human diseases.