bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards Optimization of Materials for Dye‐Sensitized Solar Cells
Authors: Luo Yanhong , Li Dongmei , Meng Qingbo 
Published: August 2009

AbstractDye‐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

AbstractDeagglomeration 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

AbstractExposure 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

AbstractIn 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

AbstractThe 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

AbstractA 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

AbstractEquilibrium 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

AbstractUrea 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

AbstractCeramic 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

AbstractA 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

AbstractGenerally 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

AbstractIn 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

AbstractTo 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

AbstractThree 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

AbstractTwo 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

Abstract2,2,6,6‐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

AbstractBisphenol 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

AbstractThe 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