bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and evaluation of thin and flexible theophylline imprinted polymer membrane materials
Authors: Hillberg Anna L. , Brain Keith R. , Allender Chris J. 
Published: January 2009

AbstractThe aim of this work was to produce a thin, flexible and diffusion able molecularly imprinted polymeric matrix with good template accessibility. Membranes were prepared using a non‐covalent molecular imprinting approach and their physical characteristics and binding capabilities investigated. Two materials were used, a poly(tri‐ethyleneglycol dimethyacrylate‐co‐methyl methacrylate‐co‐methacrylic acid) copolymer containing 14% cross‐linker and a monomer (g) to porogen (ml) ratio of 1:0.5 (A), and a blend of poly(TEGMA‐co‐MAA) and polyurethane (B). The polyurethane was added to improve membrane flexiblity and stability. The polymers were characterized using AFM, SEM and nitrogen adsorption, whilst binding was evaluated using batch‐rebinding studies. For all membranes the specific surface area was low (<10 m2/g). MIP (A) films were shown to bind specifically at low concentrations but specific binding was masked by non‐specific interactions at elevated concentrations. Selectivity studies confirmed specificity at low concentrations. KD approximations confirmed a difference in the population of binding sites within NIP and MIP films. The data also indicated that at low concentrations the ligand‐occupied binding site population approached homogeneity. Scanning electron microscopy images of membrane (B) revealed a complex multi‐layered system, however these membranes did not demonstrate specificity for the template. The results described here demonstrate how the fundamental parameters of a non‐covalent molecularly imprinted system can be successfully modified in order to generate flexible and physically tolerant molecularly imprinted thin films. Copyright © 2009 John Wiley & Sons, Ltd.
China's snow disaster in 2008, who is the principal player?
Authors: Hui Gao 
Published: January 2009

AbstractThe unprecedented snow disaster in January 2008 brought serious human and economic losses to China. It has been suggested that the La Nina event is the principal cause. But analysis indicates that in December 2007, the circulation patterns in the tropical regions are quite similar with those in January 2008. In contrast large differences existed at high latitudes, especially the Siberia high (SH) and the north polar vortex (NPV). The differences can also be found between other extreme heavy and light snow years. In the extreme heavy (light) snow years, the SH is stronger (weaker) and the NPV is deeper (shallower). But these extreme snow events don't correspond to ENSO events well. Statistical results also indicate that both the SH and the NPV are independent of ENSO. So, rather than the La Nina event, the abnormal circulations at the high latitudes may play a more crucial role in making this snow disaster. Copyright © 2009 Royal Meteorological Society
Apparent electrical conductivity integrated from layered soil profiles
Authors: Bänninger Dominik , Wunderli Hans , Flühler Hannes 
Published: January 2009

AbstractTime domain reflectometry (TDR) trace analysis aims at extracting the water content profile along TDR probes. This can be done by applying a TDR forward solver inversely. Thus, TDR‐trace inversion is basically an optimization problem. As in any optimization procedure, it is worthwhile to include as much a priori information as possible about the problem to be solved. In this study, we discuss the feasibility to use the apparent electrical conductivity as constraint for the TDR inversion. The resistors‐in‐parallel circuit can be used to integrate a multislice soil model to obtain the apparent electrical conductivity. We apply additionally Archie's law to link the water content of a particular slice with its electrical conductivity. We compare the results from this approach with measured TDR traces and show that the problem is solved exactly. Finally, we address the thin‐layer issue because thin layers with a high permittivity contrast result in a delay of the run time of an electromagnetic pulse. We test numerically whether a similar behavior can be observed for a thin layered electrical conductivity profile. Our results show that the thickness of the soil layer with respect to electrical conductivity has no effect on the apparent electrical conductivity. We conclude that the apparent electrical conductivity is appropriate as boundary condition in TDR inversion as long as a procedure is known to convert the water content of a slice to its electrical conductivity
Determination of anti‐malaria agent chloroquine using single drop liquid‐liquid‐liquid microextraction
Authors: Daneshfar Ali , Khezeli Tahere , Manafi Mohamad H. 
Published: January 2009

AbstractA simple, sensitive, and inexpensive single drop liquid‐liquid‐liquid microextraction combined with isocratic RP‐HPLC and UV detection was developed for the determination of anti‐malaria drug, chloroquine. The target compound was extracted from alkaline aqueous sample solution (adjusted to 0.5 mol/L sodium hydroxide) through a thin layer of organic solvent membrane and back‐extracted to an acidic acceptor drop (adjusted to 0.02 mol/L phosphoric acid) suspended on the tip of a 25 μL HPLC syringe in the organic layer. This syringe was also used for direct injection after extraction. The linear range was 1–200 μg/L. The LOD and LOQ were 0.3 and 1.0 μg/L, respectively. Intra‐and inter‐day precisions were less than 2.0 and 2.3%, respectively. The real samples were successfully analyzed using the proposed method. The recoveries of spiked samples were more than 94.6%.
Improved protein separation by microchip isoelectric focusing with stepwise gradient of electric field strength
Authors: Cong Yongzheng , Liang Yu , Zhang Lihua , Zhang Weibing , Zhang Yukui 
Published: January 2009

AbstractA stepwise gradient of electric field strength was proposed for microchip IEF‐based protein separation, by which after focusing at low voltages, IEF was performed by applying higher separation voltages step‐by‐step. A linear relationship between the focusing time and the inverse of the electric field strength was found. In addition, the conductivity of an established pH gradient showed a negative but nonlinear correlation with the applied voltage. Based on the above‐mentioned results, a stepwise gradient of electric field strength, ranging from 160 to 1500 V/cm was applied in the separation of proteins extracted from Escherichia coli in a straight glass microchip channel permanently coated by polyacrylamide. Compared to the conventional separation performed under a constant field strength of 750 V/cm, the increased stepwise gradient of electric field strength resulted in improved resolution and decreased focusing time, while without the negative effects of Joule heat for protein separation. All these results demonstrated that such a method might be of great significance to achieve high resolution and high‐throughput analysis of complex protein samples for microchip IEF.
Effects of long‐acting beta adrenergic agonists on vocal fold ion transport
Authors: Sivasankar Mahalakshmi , Blazer‐Yost Bonnie 
Published: January 2009

AbstractObjectives:Inhaled medications prescribed for the hypersensitive airway typically combine corticosteroids and long‐acting β2 adrenergic agonists (LABAs). The phonatory side effects of these combination treatments are widely recognized. However, there is limited understanding of the physiological changes induced by these medications that underlie the phonatory side effects. The objective of this study was to investigate the distinct effects of corticosteroids and LABAs on vocal fold mucosal physiology. Understanding the physiological changes to the vocal folds after corticosteroid and LABA treatments is necessary to prevent the prevalent vocal decrement associated with these medications.Study Design:Experimental in vitro design with treatment and control groups.Methods:Native porcine vocal fold mucosae (N = 38) were exposed to corticosteroid or LABA treatments. Ion transport was measured continuously at baseline and after treatment. To quantify the nature of ion transport, vocal folds were also treated with chloride and sodium channel inhibitors.Results:Corticosteroid treatment did not alter ion transport. Conversely, exposure to LABAs significantly increased ion transport. This increase in ion transport was transient, observed immediately after treatment in all tissue and associated with increased chloride secretion.Conclusions:The distinct effects of corticosteroids and LABAs on vocal fold physiology have not been examined to date. This study demonstrates that short‐term treatment with LABAs, but not corticosteroids, significantly increases ion transport. These findings suggest that one underlying physiological mechanism for phonatory changes associated with inhaled treatments may be related to acute alterations in vocal fold ion transport and surface hydration. Laryngoscope, 2009
Chelation therapy for neurodegenerative diseases
Authors: Bolognin Silvia , Drago Denise , Messori Luigi , Zatta Paolo 
Published: January 2009

AbstractMounting evidence suggests a central role for transition biometals in the etiopathogenesis of neurodegenerative diseases (ND). Indeed, while studying the molecular basis for this heterogeneous group of diseases, it has become increasingly evident that biometals and nonphysiological Al are often involved in pathology onset and progression, either by affecting the conformation of specific proteins or by exacerbating local oxidative stress. The apparently critical role played by metal dishomeostasis in ND makes chelation therapy an attractive pharmacological option. However, classical metal chelation approaches, relying on potent metal ligands, turned out to be successful only in those rare cases where exceptional brain metal accumulation occurs due to specific defects in metal metabolism. In contrast, metal‐targeted approaches using ligand of intermediate strength seem to be more appropriate in fighting the major ND, although their benefits are still questioned. We report here a survey of recent evidences supporting the use of a variety of metal ligands, and even functionalized nanoparticles, for the treatment of the most common ND. The beneficial neuropharmacological actions of metal‐targeted agents most likely arise from local metal redistribution rather than from massive metal removal. The perspectives for the development of new effective agents against ND are critically discussed. © 2009 Wiley Periodicals, Inc. Med Res Rev
A practical method for computing the largest M‐eigenvalue of a fourth‐order partially symmetric tensor
Authors: Wang Yiju , Qi Liqun , Zhang Xinzhen 
Published: January 2009

AbstractIn this paper, we consider a bi‐quadratic homogeneous polynomial optimization problem over two unit spheres arising in nonlinear elastic material analysis and in entanglement studies in quantum physics. The problem is equivalent to computing the largest M‐eigenvalue of a fourth‐order tensor. To solve the problem, we propose a practical method whose validity is guaranteed theoretically. To make the sequence generated by the method converge to a good solution of the problem, we also develop an initialization scheme. The given numerical experiments show the effectiveness of the proposed method. Copyright © 2009 John Wiley & Sons, Ltd.
Isothermal degradation of poly(3‐hydroxybutyrate)/organically modified montmorillonite nanocomposites
Authors: Erceg Matko , Kovačić Tonka , Perinović Sanja 
Published: January 2009

AbstractPolymer nanocomposites consisted of biodegradable poly(3‐hydroxybutyrate) (PHB) and organically modified montmorillonite Cloisite25A (OMMT), prepared by the solution‐casting method, were isothermally degraded for 120 min at 230, 235, 240, and 245°C in the nitrogen atmosphere. The addition of OMMT increases the thermal stability of PHB, and the most pronounced effect has the addition of 7 wt% of OMMT. Kinetic analysis was performed using reduced time plots and model‐free isoconversional methods. The empirical kinetic triplets (E, A, and g(α)) for the isothermal degradation of pure PHB and PHB/OMMT nanocomposites were determined. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Evaluation of embedded optical fiber sensors in composites: EFPI sensor response to fatigue loading
Authors: Etches J.A. , Fernando G.F. 
Published: January 2009

AbstractExtrinsic Fiber Fabry‐Perot Interferometric (EFPI) sensors were fabricated and embedded within a 16‐layer cross‐ply composite. The composites with and without the embedded EFPI sensors were subjected to tension/compression loading. The presence of the embedded sensor was not found to have adverse effect on the tension/compression fatigue properties. However, the performance of the EFPI sensor was found to degrade with fatigue cycles, with the introduction of a compressive element in the loading regime; samples were tested using stress ratios of −1, −2.5, and −3. Although the reasons for this observed degradation in the response of the sensor to applied strain is not known at present, it is speculated that this may be due to debonding of the key components of the sensor. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Properties and strain hardening character of polyethylene terephthalate containing Isosorbide
Authors: Gohil Ramesh M. 
Published: January 2009

AbstractPolyethylene terephthalate containing Isosorbide (PEIT) polymers made from renewable corn‐derived Isosorbide monomer exhibit a wide range of glass transition temperatures (80–180°C) and are therefore able to be used in many applications. Stress–strain curves for high Isosorbide content copolymers show strain softening, which impairs the molecular orientation during orientation of films and bottles. It is therefore necessary to find ways to modify deformation behavior of PEIT copolymers. Deformation characteristics of PEIT and other polyesters have been evaluated to define stretching parameters and necessary composition for making oriented bottles for hot fill applications. In the presence of polymeric nucleating agents, (polymeric ionomers or polyesters containing sodium ions), strain‐hardening parameters become almost temperature‐ independent below solid state deformation temperature of 125°C. We developed a methodology to achieve molecular orientation comparable with films and articles made by conventional processing of poly(ethylene terephthalate), PET. Polyesters containing sodium ions are efficient nucleating agents for PEIT, and their required concentration is dependent on deformation temperature. Both strain hardening and stress at 250% strain depend on the concentration of nucleating agents and deformation temperatures. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Effect of cellulose concentration in NMMO·H2O solution on prediction of MW and MWD of cellulose using a rheology‐based method
Authors: Zhang Huiru , Liu Xiaoyun , Li Dongshuang , Li Rongxian 
Published: January 2009

AbstractPrediction of molecular weight (MW) and molecular weight distribution (MWD) of cellulose by means of a rheology‐based method is developed. In this method, the effect of cellulose concentration in N‐methlymorpholine‐N‐oxide monohydrate (NMMO·H2O) solution on predicting results is discussed. It is shown that there is no significant effect of cellulose concentration on predicting results when the cellulose concentration in NMMO·H2O solution is high enough. Meanwhile, the obtained results are compared with those of gel permeation chromatograghy (GPC) method. The comparison shows that the calculated peak MW, polydispersity index (PDI) and MWD curves have the same trends. Consequently, it may be feasible to compare the MW and MWD of cellulose by using the rheology‐based method. In addition, the rheology‐based method is simple and fast. Therefore it is a useful and easy way to analyze the MW and MWD of cellulose in the fiber industry. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Strategies for improving graft degree of urethane derivative of 2‐hydroxymethyl methacrylate grafted onto LDPE
Authors: Ding Shenglong , Liu Mingzhu 
Published: January 2009

AbstractA novel monomer, 2‐methyl‐acrylic acid 2‐(3‐isocyanato‐2‐methyl‐phenyl carbamoyloxy)‐ethyl ester (HT), was synthesized by the reaction of 2‐hydroxymethyl methacrylate with toluene diisocyanate. The influences of solvents, temperature and catalyst, dibutyl tin dilaurate on the total yield of HT were investigated and theoptimum synthesis conditions were obtained. The obtained monomer was then used to modify low density polyethylene (LDPE) in the Haake Rheomix 600P via melt grafting copolymerization. The modified LDPE was characterized by Fourier transform infrared. During the grafting process, single‐step and two‐step procedures were compared and the results showed that the two‐step procedure was more favorable. In a two‐step procedure, the influences of melting temperatures, monomer amount, and ethylene vinyl acetate copolymer (EVA, Mn = 800–1200) on the graft degree were also investigated. The investigation confirmed that EVA acting as a dispersant could enhance the dispersion of the monomer and improve graft degree significantly, and net value of increased graft degree was about 1.5%. The better dispersion of HT in the matrix of LDPE was confirmed via scanning electron microscope after adding EVA to the system. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Development of epoxy/hyperbranched blends for resin transfer molding and vacuum assisted resin transfer molding applications: Effect of a reactive diluent
Authors: Cicala G. , Recca G. , Carciotto S. , Restuccia C.L. 
Published: January 2009

AbstractThe rheological and thermomechanical properties of some epoxy blends modified with hyperbranched polymers are reported. The effects of different percentages of a multifunctional reactive diluent were investigated to develop formulations that could be processed by RTM (Resin Transfer Molding) and VARTM (Vacuum‐Assisted Resin Transfer Molding). The diluent chosen for the study was trimethylolpropane triglycidyl ether, which was added at three percentages: 10%, 20%, and 40%. The hyperbranched modifier used was aliphatic polyester of the fourth pseudo‐generation commercialized by Perstorp as Boltorn™ H40. A cure cycle composed of a precure at 135°C followed by a postcure at 180°C was adopted. The blends were thoroughly characterized in both the unreacted and cured states. The unreacted blends were characterized by parallel plate rheometry, both in dynamic and isothermal mode. Analysis of the cured samples was carried out through dynamic mechanical tests after precuring and postcuring. The diluent had an impact, due to its peculiar structure, on both the uncured and cured properties. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Ethylene vinyl acetate/ethylene propylene diene terpolymer‐blend‐layered double hydroxide nanocomposites
Authors: Kuila T. , Srivastava S.K. , Bhowmick Anil K. 
Published: January 2009

AbstractEthylene vinyl acetate (EVA‐45)/ethylene propylene diene terpolymer (EPDM) blend‐layered double hydroxide (LDH) nanocomposites have been prepared by solution blending of 1:1 weight ratio of EVA and EPDM with varying amounts of organo LDH (DS‐LDH). X‐ray diffraction and transmission electron microscopy analysis suggest the formation of partially exfoliated EVA/EPDM/DS‐LDH nanocomposites. Measurement of mechanical properties of the nanocomposites (3 wt% DS‐LDH content) show that the improvement in tensile strength and elongation at break are 35 and 12% higher than neat EVA/EPDM blends. Dynamic mechanical thermal analysis also shows that the storage modulus of the nanocomposites at glass transition temperature is higher compared to the pure blend. Such improvements in mechanical properties have been correlated in terms of fracture behavior of the nanocomposites using scanning electron microscopy analysis. Thermal stability of the prepared nanocomposites is substantially higher compared to neat EVA/EPDM blend, confirming the formation of high‐performance polymer nanocomposites. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
The rheological modification of talc‐filled polypropylene by epoxy‐polyester hybrid resin and its effect on morphology, crystallinity, and mechanical properties
Authors: Jahani Yousef , Ehsani Morteza 
Published: January 2009

AbstractReactive mixing of polypropylene (PP) and talc with epoxy‐polyester resin was preformed using a corotating twin screw extruder, and the rheology, morphology, crystallization behavior, and mechanical properties of composites were evaluated. The melts of composites mixed with resin exhibited yield stress and the variation of viscosity against frequency can be approximated in two lines with various slopes. The measurement of the suspension viscosity can be used to characterize the microstructural state of dispersion. Empirical formula was used to relate viscosity with particle concentration, and the analysis showed that the maximum volume fraction increases by using small amount of epoxy resin in the formulations. The morphological study of composites by scanning electron microscopy revealed that the use of resin improved the dispersion of talc in PP, which leads to the arrangement of talc platelets in the direction of flow even close to wall of the mold. The differential scanning calorimetry showed that the epoxy resin suppressed the nucleation effect of talc on PP while the degree and rate of crystallization increased. The compatibilization by maleic anhydride‐grafted polypropylene showed a noticeable increase in tensile strength of composites reactively mixed with epoxy resin. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Polyurethanes from tung oil: Polymer characterization and composites
Authors: Mosiewicki M.A. , Casado U. , Marcovich N.E. , Aranguren M.I. 
Published: January 2009

AbstractA natural polyol was obtained from tung oil (TO) to be further used in the formulation of rigid polyurethane polymers. The synthesis of the polyol was carried out in two steps: first hydroxylation of the double bonds in the fatty acid chains of the unsaturated oil and then, alcoholysis of the hydroxylated oil with triethanolamine. The chemical analysis (titration, FTIR, 1H NMR) of the unmodified TO, the hydroxylated tung oil, and the alcoholized hydroxylated tung oil‐based polyol indicates that the hydroxyl content increased significantly after the hydroxylation and alcoholysis reactions. The modified TO was subsequently used as the polyol component in the formulation of reinforced rigid polyurethanes. Wood flour (WF) and microcrystalline cellulose were the reinforcements chosen to be incorporated in these materials. Physical, thermal, and mechanical properties of the neat and reinforced polyurethanes were measured and analyzed. An excellent dispersion of the WF in the matrix, confirmed by scanning electron microscopy, was observed in the polyurethane reinforced with WF. This system also presented the highest modulus and strength. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Current drug management of BPH in primary care
Authors: Taylor Claire , Foley Charlotte , Kirby Roger 
Published: January 2009

AbstractThe range of drug treatments for BPH, alone and in combination, allow many patients to be managed in primary care and delay the need for referral. Our Drug review considers their efficacy and side‐effects, followed by sources of further information, an analysis of prescription data and the Datafile. Copyright © 2006 Wiley Interface Ltd