bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymer characterization by ultrasonic wave propagation
Authors: Lionetto Francesca , Maffezzoli Alfonso
Published: July 2010

The propagation of low‐intensity ultrasound in polymers, acting as a high‐frequency dynamic mechanical deformation, can be successfully used to monitor changes in the modulus of polymers associated with glass transition, crystallization, cross‐linking, and other chemical and physical phenomena related to changes in the viscoelastic behavior, such as gelation phenomena. The velocity of sound is related to the polymer storage modulus and density, whereas the absorption of ultrasonic waves is related to the energy dissipation in the material and, therefore, to the loss modulus. Accordingly, ultrasonic measurements have been used by several authors to monitor the evolution of the viscoelastic moduli of polymers as a function of time or temperature and, recently, become a characterization technique of its own right, generally known as ultrasonic dynamic mechanical analysis (UDMA). Often the technique is used in conjunction with rheological methods as a means of providing a better insight into the viscoelastic behavior of polymer systems. As yet UDMA is underutilized primarily because of the low operating temperatures (usually below 100○C) of commercially available ultrasonic transducers, and also due to the requirement of a coupling medium to ensure an efficient energy transfer mechanism between the transducer and the test material. Despite these limitations, this paper shows that the use of ultrasonics is potentially a powerful method for the characterization of polymers, particularly as a tool for online monitoring of events occurring during polymer processing and in the manufacture of polymer matrix composites. The aim of this paper is to review the progress made in recent years, highlighting the potential and reliability of UDMA for monitoring physical transitions in polymers such as glass transition, melting, crystallization, as well as physical changes taking place during curing of thermosetting resins. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:63–73, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20124
Photopolymerization and properties of fluorene‐based dimethacrylate monomer used as a root canal sealer
Authors: He Jingwei , Luo Yuanfang , Liu Fang , Lin Zhengmei , Ling Junqi , Jia Demin
Published: July 2010

The methacrylate resin‐based sealers have attracted wide attention with easy handling, superior aesthetic qualities, good mechanical properties, and excellent adhesive ability with dentin. 2,2‐bis[4‐(2′‐hydroxy‐3′‐methacryloyloxypropoxy)phenyl]‐propane (Bis‐GMA) is the main component of a new developing commercial root canal sealer “Epiphany,” which is one of the methacrylate resin‐based sealers. To further reduce polymerization volume shrinkage of bis‐GMA, 9,9′‐bis[4‐(2′‐hydroxy‐3′‐methacryloyloxypropoxy)‐phenyl]fluorene (HMPF) with higher molecular weight and larger molecular volume was selected to replace bis‐GMA as one of the components of the root canal sealer in this study. Photopolymerization behavior of a mixture of HMPF and triethylene glycol dimethacrylate (TEGDMA) was investigated by FTIR spectroscopy. Degree of conversion, volume shrinkage, and water sorption of various HMPF/TEGDMA formulations were measured and compared with a 50:50 bis‐GMA/TEGDMA formulation. The results illustrated that, with increasing content of HMPF in HMPF/TEGDMA system, the double bond conversion of the cured resin increased and volume shrinkage decreased. Its water sorption increased with increasing content of HMPF when the content was less than 50% and decreased with an increase in HMPF when the content was more than 50%. Compared with bis‐GMA/TEGDMA system, HMPF/TEGDMA had lower double bond conversion, lower polymerization shrinkage, and higher water sorption. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:108–116, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20125
Thermoplastic matrix towpreg production
Authors: Silva J. F. , Nunes J. P. , Velosa J. C. , Bernardo C. A. , Marques A. T.
Published: July 2010

This work was carried out to establish the processing window for the cost‐efficient production of thermoplastic matrix towpregs with a recently developed powder‐coating equipment. Three different fiber‐reinforced thermoplastic matrix systems were studied: one for highly demanding markets (carbon fiber/Primospire™) and other two for commercial applications (glass/polypropylene and glass/polyvinyl chloride). The mechanical properties determined on compression‐molded composite components obtained from the produced towpregs were also evaluated. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:80–85, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20174
Ultrasonic welding of advanced thermoplastic composites: An investigation on energy‐directing surfaces
Authors: Villegas Irene Fernandez , Bersee Harald E. N.
Published: July 2010

Ultrasonic welding is considered as one of the most promising welding techniques for continuous fiber‐reinforced thermoplastic composites. Intermolecular friction within the bulk, resulting from the application of ultrasonic waves applied on the surfaces, generates the heat required for welding to take place at the interface of the joining members via the so‐called “energy directors” (EDs). Energy directors consist of resin protrusions or artificially produced asperities on the composite surfaces and play an important role both in the welding process and in the quality of the resulting welds. This paper presents the results of a study on the effects of configuration of different EDs on the ultrasonic welding of carbon fiber/polyetherimide advanced thermoplastic composites in a near‐field setup. Triangular EDs were molded on the surface of consolidated composite laminates with a hot platen press. Single lap‐shear‐welded samples were produced to investigate the influence of the orientation of the EDs with respect to the load direction, as well as the configuration of multiple EDs. The results indicate that the configuration of multiple transverse EDs was more effective in covering the overlap area, once the resin has melted, causing only a minimum fiber disruption at the welding interface. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:112–121, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20178
Polyamide–imide membranes with surface immobilized cyclodextrin for butanol isomer separation via pervaporation
Authors: Wang Yan , Chung Tai Shung , Wang Huan
Published: July 2010

A novel cyclodextrin (CD) derivative, m‐xylenediamine‐β‐cyclodextrin (m‐XDA‐β‐CD), has been synthesized and used to graft β‐CD on membrane surface for the pervaporation separation of butanol isomers. The reaction mechanisms for the m‐XDA‐β‐CD synthesis and the membrane surface grafting are confirmed by FTIR and TGA. The as‐fabricated novel CD‐grafted polyamide‐imide (PAI) membranes show homogeneous morphology and significant improved separation performance as compared to the unmodified PAI membranes and PAI/CD mixed matrix membranes made of physical blends. The effects of chemical modification time and dope concentration on the asymmetric membrane have been studied. The optimal separation performance can be found with the CD‐grafted PAI membrane cast from a 22 wt % dope concentration, which exhibits a total butanol flux of 15 g/m2/h and a separation factor of 2.03. This newly developed membrane with surface‐immobilized CD may open new perspective for the development of next‐generation high‐performance pervaporation membranes for liquid separations. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Modeling infinite dilution and Fickian diffusion coefficients of carbon dioxide in water
Authors: Mutoru J. Wambui , Leahy‐Dios Alana , Firoozabadi Abbas
Published: July 2010

We propose a new model for calculating infinite dilution diffusion coefficients for carbon dioxide and water mixtures. The model takes into account temperature dependence of the dipole moment of water and polarizability of CO2, and fits experimental CO2H2O data at low and high pressures with an accuracy of 4.9%. Remarkably, the proposed model also accurately predicts infinite dilution diffusion coefficients for other binary water mixtures where solute polarizability is close to that of CO2, such as CH4, C2H6, C3H8, and H2S. Moreover, we present—to the best of our knowledge—the first predictions of composition‐based Fickian diffusion coefficients for CO2H2O mixtures over the temperature range 298.15–413.15 K, and pressures up to 50 MPa. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Monodisperse droplet formation through a continuous jet break‐up using glass nozzles operated with piezoelectric pulsation
Authors: Wu Winston Duo , Lin Sean Xuqi , Chen Xiao Dong
Published: July 2010

In this article, a glass nozzle driven by piezoceramics is used to experimentally study the continuous generation of a stream of monodisperse droplets from the breakup of a liquid jet. The approach is demonstrated by examining the breakup dynamics of three distinct liquids. The droplet formation process has been found to be highly controllable and reproducible. The dependence of nozzle performance on liquid properties, flow rate, and disturbance frequency has been investigated. The ratio between the actual disturbance frequency and Reynolds number, ω, is employed at first to represent the operating range that facilitates monodisperse droplet formation. Then, the dimensionless quantity ω*, obtained by multiplying ω by the viscous characteristic time, r/(μ/ρ), has been shown to collapse the data for the lower and higher bounds of the actual disturbance frequency ranges that secure monodispersity of the droplets of all the samples tested. The impacts of liquid flow rate and disturbance frequency on the monodisperse droplet size and spacing between two neighboring droplets have been investigated and discussed. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Continuous production of miniemulsions using in‐line SMX elements
Authors: El‐Jaby Ula , Cunningham Michael , McKenna Timothy F. L.
Published: July 2010

The preparation and stabilization of miniemulsion systems using SMX static mixers (in line with a pump and reservoir tank) and in situ generated surfactants is presented. Neutralization of a water‐soluble base with an oil‐soluble long chain acid, generating a in situ surfactant at the interface, results in rapid stabilization and emulsification compared to preformed surfactant that must diffuse to, then adsorb on the droplets. As the flow rates (50–75 g/s) and number of mixing elements (7–21 SMX mixers) in series increase, the emulsification time reduces by ∼30‐folds (14 vs. 0.5 min). The reduction in the emulsification time required to produce a stable emulsion at 75 g/s and 21 mixing elements more than compensated for the higher pressure in the emulsification loop, consuming five times less energy than what would be consumed when working at 50 g/s and 7 SMX elements. Subsequently, with the rapid emulsification step, it was possible to test the feasibility of a continuous process for direct emulsification followed by polymerization. Comparing this process with a batch process, similar results for the number of particles/number of droplets ratio and conversion were obtained, but the continuous process was accomplished in a single step. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Developing an effective community conservation program for cotton‐top tamarins (Saguinus oedipus) in Colombia
Authors: Savage A. , Guillen R. , Lamilla I. , Soto L.
Published: July 2010

Developing effective conservation programs that positively impact the survival of a species while considering the needs of local communities is challenging. Here we present an overview of the conservation program developed by Proyecto Tití to integrate local communities in the conservation of Colombia's critically endangered primate, the cotton‐top tamarin (Saguinus oedipus). Our comprehensive assessment of the threats effecting the long‐term survival of the cotton‐top tamarin allowed us to establish the primary components of our program. Proyecto Tití has three areas of emphasis: (1) scientific studies detailing the biology and long‐term survival of the cotton‐top tamarin, (2) conservation education programs to increase public awareness and conservation knowledge, and (3) community empowerment programs that demonstrate a valuable economic incentive to protecting wildlife and forested areas in Colombia. This integrated approach to conservation that involves local communities in activities that benefit individuals, as well as wildlife, has proven to be remarkably effective in protecting cotton‐top tamarins and their forested habitat. Our bindes program, which uses small cook stoves made from clay, has demonstrated a marked reduction in the number of trees that have been harvested for firewood. Developing environmental entrepreneurs, who create products made from recycled plastic for sale in national and international markets, has had a significant impact in reducing the amount of plastic that has been littering the environment and threatening the health of wildlife, while creating a stable economic income for rural communities. Proyecto Tití has provided economic alternatives to local communities that have dramatically reduced the illegal capture of cotton‐top tamarins and forest destruction in the region that has positively impacted the long‐term survival of this critically endangered primate. Am. J. Primatol. 72:379–390, 2010. © 2009 Wiley‐Liss, Inc.
Wechselwirkungen zwischen amyloidogenen Proteinen und Membranen: Modellsysteme liefern mechanistische Einblicke
Authors: Butterfield Sara M. , Lashuel Hilal A.
Published: July 2010

Die Toxizität amyloidbildender Proteine ist mit ihrer Wechselwirkung mit Membranen korreliert. Bemerkenswerterweise führen Bindungsereignisse zwischen amyloidogenen Proteinen und Membranen beiderseits zu Strukturstörungen, die mit Toxizität assoziiert sind. Membranoberflächen vermitteln die Umwandlung amyloidbildender Proteine in toxische Aggregate, amyloidbildende Proteine wiederum beeinträchtigen die strukturelle Integrität der Zellmembran. Neuere Untersuchungen an künstlichen Modellmembranen haben eine bemerkenswerte Ähnlichkeit im Mechanismus der Membranpermeabilisierung von amyloidbildenden Proteinen, porenbildenden Toxinen und antimikrobiellen Peptiden aufgezeigt.
Li‐doped nanosized TiO2 powder with enhanced photocalatylic acivity under sunlight irradiation
Authors: Bouattour Soraa , Kallel Wannes , Botelho do Rego Ana Maria , Vieira Ferreira L.F. , Machado I. Ferreira , Boufi Sami
Published: July 2010

This work reports on the synthesis of Li‐doped TiO2 nanoparticles using the sol–gel process and solid‐state sintering, and investigates their potential use as a photocatalyst for degradation under sunlight excitation of different organic model compounds in aqueous solution. The structure of the nanocrystals was examined by X‐ray diffraction, UV‐vis ground state diffuse reflectance absorption spectra and X‐ray photoelectron emission spectroscopy. Results showed that samples prepared by sol–gel process and calcined at 400 °C are composed of a mixture of anatase and rutile phases, in contrast to the one prepared by solid‐state sintering, which exhibits an anatase phase with Li being involved in a spinel phase. The photocatalytic degradation of aqueous solutions of different aromatic compounds was successfully achieved under sunlight excitation in presence of Li‐doped TiO2 prepared via sol–gel process. It was shown that the calcination temperature and the preparation mode greatly affect the photocatalytic efficiency. Copyright © 2010 John Wiley & Sons, Ltd.
Formation of atractylone liposomes by rapid expansion from supercritical to surfactant solution
Authors: Wen Zhen , You Xinkui , Liu Bo , Zheng Zongkun , Pu Yitao , Jiang Lingzhi , Li Qiong
Published: July 2010

Atractylone is a sesquiterpene oxide‐derivative in volatile oil extracted from Atractylodes macrocephala Koidz., a famous Chinese traditional medicine (suppressing tumour growth). However, the low solubility and poor stability of atractylone lead to poor pharmacokinetic performance in the body. As a biocompatible carrier system, liposomes protect encapsulated atractylone molecules from degradation and improve the solubility of atractylone. The purpose of this study is to investigate the possibility of incorporation of atractylone into liposomes by the process of rapid expansion from supercritical to surfactant solution (RESSS). In this process, the solution of liposomal materials and atractylone solvated in the mixture of supercritical carbon dioxide (SC‐CO2)/ethanol was sprayed into a surfactant solution. The surfactant stabilized the liposomes by preventing bubbles overflowing and liposomes agglomeration during the spraying process. The encapsulating performance and particle size distribution of liposomes could be controlled by changing the pre‐expansion and expansion conditions. When the solution pre‐expanded in 15% (mole percent, mol/mol) SC‐CO2/ethanol at 30 MPa and 65 °C was sprayed into 5.0% (w/w) Poloxamer l88 solution at a flow rate of 2 l/min, the entrapment efficiency and average particle size of liposomes were 87.25% and 124 nm, respectively, which achieved the standards of Chinese pharmacopoeia. Compared with the liposomes prepared by thin film dispersion, the liposomes formed by the RESSS process had smaller particle sizes with a uniform and narrow distribution. The results show that the RESSS process provides an innovative method for improvement of encapsulation efficiency and minimization of liposomes particle agglomeration. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.
Application of air dispersion modelling for exposure assessment from particulate matter pollution in mega city Delhi
Authors: Mohan Manju , Bhati Shweta , Rao Archana
Published: July 2010

The severe health hazards of respirable suspended particulate matter (RSPM or PM10) are well known, and control of RSPM is an integral part of any effective air quality management plan. The proposed study addresses the implementation of an air quality model for exposure assessment subsequent to its validation for the particulate matter in a megacity in India, namely Delhi, where RSPM concentrations most often exceed the ambient air quality standards. The model validation has been accomplished here for the total suspended particulate matter (TSPM) for which an extensive source inventory is available along with the requisite air quality data. A regulatory air dispersion model of US Environmental Protection Agency, AERMOD (Aermic Dispersion Model version 07026), which is a steady‐state Gaussian Plume Model with improved atmospheric boundary layer physics, has been utilized for this purpose. Model validation shows a satisfactory model performance based on various statistical indicators. Subsequently, RSPM values are obtained from TSPM estimates and applied for exposure assessment for predefined emission control scenarios. The results from the model have been used to analyse mortality change associated with two hypothetical scenarios, namely, (1) reduction of vehicular traffic emissions by a fixed amount due to introduction of metro rail and compressed natural gas based buses in the city and (2) shift to a cleaner fuel in all the thermal power plants. The results from the exposure assessment study showed the importance of control of vehicular emission in improving the air quality and accrued health benefits. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.
Effects of heat and chemical reactions on peristaltic flow of Newtonian fluid in a diverging tube with inclined MHD
Authors: Nadeem S. , Akbar Noreen Sher
Published: July 2010

The problem of magnetohydrodynamics (MHD) in connection with peristaltic transport has attracted significant attention due to its wide range of engineering applications. In this paper, we have investigated the peristaltic flow of an incompressible MHD Newtonian fluid in an inclined non‐uniform tube in the presence of an inclined magnetic field and heat and mass transfer effects. The flow is investigated in a wave frame of reference moving with the velocity of the wave. The governing equations of a two‐dimensional fluid have been simplified under long wave length and low Reynolds number approximations. Exact solutions have been obtained for the velocity, temperature, and concentration profiles. The expression for pressure gradient is calculated using numerical integration. The graphical results are presented in order to interpret the various physical parameter of interest for five different wave forms. Trapping phenomena have been also discussed. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.
Effects of bivalve shell particles of hyriopsis cumingii on the performances of epoxy resin studied by positron annihilation
Authors: Sun Xudong , Zeng Minfeng , Wang Yun , Ji Genzhong , Yao Xiandong , Shen Yongmiao , Chen Ning , Yan Fengyuan , Wang Baoyi , Qi3 Chenze
Published: July 2010

Mussel shell particles sized in micrometer level have been prepared with a ball mill. The X‐ray powder diffractrometer (XRD) and Fourier transform infrared (FTIR) results proved that the shell particles contained mainly CaCO3 in the form of aragonite, together with small amount of organic phase. EP modified with shell particles showed a much rougher fracture surface than unfilled EP. The mechanical properties have been improved obviously by adding the shell particles in EP from 1% to 5%. The particle would occupy a number of free volume holes of the EP matrix. This would lead to a decrease in the total free volume concentration of the composites. The particles acted as a bridge to make more molecules interconnected for the good interfacial adhesion, resulting in a reduction of the free volume hole size in the interfacial layers. I2 reached its highest value when 3% shell particles were added and then decreased as the shellparticles content increased. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Structure and mechanical properties of soy protein materials plasticized by Thiodiglycol
Authors: Kumar Rakesh , Wang Linxiang , Zhang Lina
Published: July 2010

Thiodiglycol (TDG) is a relatively nontoxic compound from organic wastes. By using TDG as a plasticizer with weights from 2.5 to 40%, we prepared soy protein isolate (SPI) films by a compression‐molding technique at 140°C and 15 MPa. The TDG‐plasticized films (SPI–TDG films) were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, dynamic mechanical thermal analysis, thermogravimetric analysis, optical transmittance, and water uptake experiments. The SPI–TDG film plasticized with 25% TDG exhibited good mechanical properties, such as a tensile strength and modulus of 20.3 and 582 MPa, respectively, whereas the SPI–glycerol film with 25% glycerol had a tensile strength and modulus of 16.2 and 436 MPa, respectively. The results from the thermogravimetric analysis and water uptake experiments indicated that the thermal stability and water resistance of the TDG‐plasticized SPI materials were higher than that of the glycerol‐plasticized one. The improvements in the mechanical properties, water resistance, and thermal stability of the SPI–TDG films could be attributed to the strong intermolecular hydrogen bonding between soy protein and TDG and the presence of fewer hydroxyl groups in TDG, as compared structurally with glycerol. This study provided a new plasticizer for the preparation of soy protein materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and rheological behavior of hydrophobically modified block copolymers
Authors: Rodrigues Jorge de A. , Nascimento Regina Sandra V.
Published: July 2010

Hydrophobically modified polymers were synthesized via esterification reactions between a commercial triblock copolymer composed of ethylene oxide (EO) and propylene oxide (PO) segments (EO20PO70EO20) and lauric and oleic acids. Rheological studies of aqueous systems containing the original copolymer and the synthesized products were performed to evaluate the effects of chemical modification, the presence of salt, and temperature on the rheology of the systems due to changes in the micellar structures. It was verified that the systems containing the synthesized products presented shear‐thinning behavior even in the absence of salt. In addition, increasing the temperature and salt concentration enhanced the hydrophobic character of the poly(propylene oxide) segment and reduced the hydration of the poly(ethylene oxide) segment; this favored the adequate packing needed to form long, wormlike micelles and resulted in pronounced shear thinning. The formation of a complex micelle structure probably occurred in the systems above the critical micellar temperature of the original copolymer because under this condition the molecules presented three alternate hydrophobic segments that had to dive into the micelle structure. The formation of long, wormlike micelles was also evidenced by the Maxwellian behavior observed in rheological oscillatory measurements. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of maleic acid polymer for use as scale deposits inhibitors
Authors: Benbakhti A. , Bachir‐Bey T.
Published: July 2010

The problem of scale formation in oil field production facilities is encountered as a result of mixing of injection water (Lias) rich in sulfate with formation water (Ordovicien) rich in barium.1 A large number of methods have been developed for the prevention of these deposits. In this work, poly(maleic acid) was studied to ascertain its suitability as an inhibitor of barium sulfate scale deposits. It was synthesized by a free radical solution polymerization. Two different initiators were used namely a potassium persulfate and a redox system composed of potassium persulfate/sodium‐hypophosphite monohydrate. Their concentrations were varied to obtain low‐molecular weight polymers. Physical and chemical properties of the polymers obtained were measured by infrared and UV/VIS spectrometry, solubility test, viscosimetry, refractometry, and liquid chromatography. The effectiveness of poly (maleic acid) formulations as scale inhibitor was studied by turbidimetric tests. The most effective inhibitor formulation was found to be that based on poly(maleic acid) prepared via a redox initiating system. This polymer, used at a concentration of 3 ppm, presented the highest effectiveness namely 96% and 88% at room and oil well temperature, respectively, when compared with two commercial inhibitors. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Positron Lifetime Spectroscopy and Differential Scanning Calorimetric study of polystyrene‐based composites with fly ash, cenospheres, and calcium aluminosilicate as fillers
Authors: Altaweel Abdullah M.A. Mohamad , Ranganathaiah C. , Siddramaiah B.
Published: July 2010

Polystyrene‐based composites with Fly ash, Cenospheres, and Calcium aluminosilicate as fillers have been examined for their mechanical and microstructure properties. Free volume measurements have been carried out using Positron Lifetime Spectroscopy to probe the microstructural features of the composites. Incorporation of fly ash, cenospheres, and calcium aluminosilicate improved the thermal properties of the composites due to increased Tg of the composites as revealed by the DSC data. Also, it was observed that the mechanical properties of calcium aluminosilicate filled composites improved more compared to fly ash and cenospheres filled composites. We attribute these favorable changes to the higher silica content of calcium aluminosilicate on account of possible interactions between the polymer matrix and silica and to some extent from particulate size. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Comparison of polyimide/multiwalled carbon nanotube (MWNT) nanocomposites by in situ polymerization and blending
Authors: Wu Kuan‐Lung , Chou Shang‐Chih , Cheng Yao‐Yi
Published: July 2010

In this research, multiwalled carbon nanotube (MWNT) was oxidized and then modified to form carboxylic groups (COOH) on the surface and the end of the tube. After that, the MWNT was added to polyimide matrix to enhance its mechanical and electrical properties by in situ polymerization and blending. The PI/MWNT composites were obtained by spin coating and multistep thermal curing process. The comparison of in situ polymerization and blending as well as the effect of unmodified and modified MWNT were discussed in this study. The results indicate that in situ polymerization is able to make a perfect dispersion by adding modified MWNT into polyimide matrix. Thermal and mechanical properties of the composites can be improved by hydrogen bonding interaction between the modified MWNT and polyimide matrix. Electrical resistance of the composites can be decreased to meet the criterion of electrostatic charge (ESC) mitigation as the surface resistance is reduced into the range of 106–1010 Ω/cm2 by adding modified MWNT. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Constrained multivariable stable predictive control based on Toeplitz equation
Authors: Liu Bin , Su Hongye , Jiang Zheng , Fang Kangling
Published: July 2010

A stable constrained multivariable predictive control algorithm based on the Toeplitz predictive equation is presented. An analytical method for transformation between left and right coprime factorization of multivariable system is put forward, and then an unconstrained control law and its stable condition are given. Furthermore, for the constrained multivariable controlled system, a predictive controller and its asymptotically stable condition are presented and proved. Finally, the constrained receding horizon optimization is transformed into a typical linear matrix inequality (LMI) problem and solved. The detailed control algorithm is depicted in a numerical example, and the simulation results reveal the effectiveness and practicability of the presented algorithm.

Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Assessing the on‐road route efficiency for an air‐express courier
Authors: Lin Erwin T. J. , Lan Lawrence W. , Hsu Cathy S.T.
Published: July 2010

This paper proposes an EXO‐CAT data envelopment analysis (DEA) model to evaluate the efficiency of on‐road activities (pickup and delivery) for an air‐express courier on a route‐by‐route basis. The proposed model combines the constraints of exogenously fixed inputs DEA and categorical DEA to account for the continuous and discrete external environmental factors affecting the courier route efficiency. We select labor, route length (a proxy of fuel consumption), and vehicle capacity as the inputs; number of documents delivered, number of boxes delivered, number of documents picked‐up, and number of boxes picked‐up as the outputs. A case study with 248 on‐road routes currently operated by an air‐express courier in Taiwan is undertaken. It is found that stop density, travel speed, and service area type have significant influences on the couriers' route efficiency. Based on the detailed DEA results, the managers do not need to perform check‐rides for all routes; instead, they need only to focus on the most inefficient ones. Such DEA results can also be applied to develop new projects or make judgments on investing any new on‐road routes. Copyright © 2010 John Wiley & Sons, Ltd.
Zur Auswahl eines geeigneten Verfahrens für die Berücksichtigung der Mitwirkung des Betons auf Zug
Authors: Quast Ulrich
Published: July 2010

Die Auswahl eines geeigneten Verfahrens zur Berücksichtigung der Mitwirkung des Betons auf Zug sollte nach DIN 1045‐1:2001‐07, 8.5.1 (9), in Abhängigkeit von der jeweiligen Bemessungsaufgabe getroffen werden. In den Erläuterungen zu DIN 1045‐1 wird im Heft 525 des DAfStb als einziges Verfahren nur die Verringerung der Betonstahldehnung mit einer modifizierten Spannungs‐Dehnungslinie für Betonstahl erläutert. Verfahren, die mittlere wirksame Betonzugspannungen in der Betonzugzone berücksichtigen, werden erwähnt aber nicht erläutert. Mit den Ergebnissen nachgerechneter Moment‐Verkrümmungs‐Werte von Stahlbetonröhren aus drei Versuchen mit unterschiedlichen Längskräften wird gezeigt, dass die Mitwirkung des Betons auf Zug mit dem Verfahren nach Heft 525 DAfStb nur bei reiner Biegung befriedigend erfasst wird. Bei Biegung mit Längskraft werden besser mittlere wirksame Betonzugspannungen berücksichtigt. Es werden vier unterschiedliche Ansätze für die Betonzugspannungen besprochen.

On the selection of an adequate method for considering the contribution of concrete in tension. The selection of an adequate method for considering the contribution of concrete in tension should according to DIN 1045‐1:2001‐07, 8.5.1 (9), be chosen with respect to the particular design problem. The explanations to DIN 1045‐1 in book 525 from DAfStb describe only one method, the method which reduces the steel strain taking a modified stress‐strain relationship into account. Methods that consider mean effective concrete stresses in tension are mentioned but not explained. The results of recomputed moment‐curvature values from three tests with different longitudinal forces show that the method in book 525 DAfStb covers the contribution of concrete in tension only for reinforced concrete members without longitudinal forces. For members with longitudinal forces methods with mean effective concrete stresses give better agreements. Four different assumptions for the concrete stresses in tension are discussed.
Static and dynamic light scattering from dilute insulin solutions
Authors: Bohidar Himadri B. , Geissler Erik
Published: July 2010

Static and dynamic light‐scattering measurements are reported on zinc‐insulin at room temperature (21 ± l°C) and pH = 6.88 in 0.1M NaCl aqueous solution. The experiments were performed at very low concentration, in the range 0.12 × 10−4 to 0.90 × 10−4 g cm−3. Within experimental error, we find no evidence for a critical micellar concentration in this system. The aggregation phenomenon starts immediately after preparation of the solutions, and takes several days to come to stable equilibrium. The concentration dependence of the diffusion coefficients, Dz, = Do (1 — kDC), is negative, and kD was observed to decrease as a function of time, while the aggregate size was found to increase. The equivalent concentration coefficient, −2BMW, obtained from static light scattering, showed a similar behavior, and, within experimental error, was found to be numerically equal to kD. From the relation found between the diffusion coefficient at infinite dilution and the molecular weight of the aggregates, log D0 = −0.240 log Mw − 5.077, we deduce that the insulin aggregates are compact structures with a characteristic radius of 0.71 Å/(dalton)1/3, surrounded by a hydration layer of a thickness of 8.0 Å. The equilibrium aggregation number is approximately 10.
Potential‐Energy surface for double‐helical DNA with Watson‐Crick Pairs. I. Complete scanning in the space of torsion angles
Authors: Neyfack Yu. A. , Tumanyan V. G.
Published: July 2010

Complete scanning of correct double‐helical DNA structures was performed in the space of torsion angles using rapid analytical procedures for generation of regular double helices with Watson‐Crick base pairs. Potential energy of structures was calculated by pair‐wise potential functions and used as necessary condition to single out physically meaningful forms. We found 12 discrete potential wells containing these physically meaningful forms, with only one well containing all classical forms (A, B, etc.). On the basis of the new structures listed, alternative models for DNA and DNA‐like polymers and appropriate conformations for fluctuations leading to DNA bending and kink formation are suggested.
Characterization of the transition state of lysozyme unfolding. II. Effects of the intrachain crosslinking and the inhibitor binding on the transition state
Authors: Segawa Shin‐Ichi , Sugihara Mitsuru
Published: July 2010

The reversible refolding of a lysozyme derivative containing an extra crosslink between Glu 35 and Trp 108 was observed at pH 3.7 in solutions of 4.5M LiBr and 4.SM 1‐PrOH. The rate constants of unfolding and folding for crosslinked lysozyme were compared with those for intact lysozyme. In LiBr solutions, the crosslinking greatly increases kf but only slightly decreases kuf. This means that the crosslinking restricts possible conformations of the U state to some conformations on the folding pathway, whereas the possible conformations of the transition state are little restricted. Although the crosslinking produces an apparently different effect on the rate constants in a PrOH solution, this could be explained by assuming that the crosslinking counteracts the effect of PrOH on the transition state. These observations suggest that the Glu 35 and Trp 108 of intact lysozyme already come into contact with each other in the course of refolding to the transition state. Kinetics of the unfolding and folding reactions of intact lysozyme were measured in the presence of 8mAf (NAG)3. The apparent folding rate (k) was nearly equal to kf, while the apparent unfolding rate (k) decreased sixfold. This means that the inhibitor binding stabilizes the native conformation but makes no contribution to the stabilization of the transition state. Specific interactions between (NAG)3 and the cleft of lysozyme become available only at the last stage of folding.
Conformational flexibilities in malformin A
Authors: Mitra Alok K. , Chandrasekaran R.
Published: July 2010

The linked‐atom‐least‐squares (LALS) technique has been applied to generate exactly cyclized and stereochemically satisfactory conformations of the cyclic pentapeptide, malformin A, which contains an intramolecular disulfide bridge across a D‐Cys—D‐Cys linkage. Consistent with theoretical, ir, and x‐ray evidence from studies on analogs of the LKiysteinyl—L‐cysteine disulfide, it is shown that the peptide bond across the SS bridge in malformin A can retain a cis configuration. The two all‐trans structures proposed earlier by A.E. Tonelli [(1978) Biopolymers 17, 1175–1179] from solution nmr data have also been analyzed. Both P‐(χs ∼ 90°) and M‐(χs ∼ −90°)‐type helicity of the SS bridge are found to be accessible in both the trans and the cis models in which the respective conformations of the homodetic rings are essentially preserved. The details of six different conformational states and their relative energies have been evaluated and compared. Our findings, which suggest that a variety of conformational states are accessible to malformin A, are compatible with other published results from solution studies. On the basis of hydrogen‐bonding interactions, a model is proposed to explain how malformin A might be inactivated specifically by L‐Hyp, and not by L‐Pro or other amino acids, as has been observed from in vivo investigations [Buckhout, T.J. & Curtis, R.W. (1976) Nature 260, 435–436]
Characterization of the fluorescence of the protamine thynnine and studies of binding to double‐stranded DNA
Authors: Ausio Juan , Greulich Karl Otto , Haas Elisha , Ellenwachtel
Published: July 2010

The protamine thynnine is an arginine‐rich protein approximately 30 amino acids long with a tyrosine in the middle of its sequence. Its fluorescence decay kinetics can be described by a biexponential function with lifetimes of 0.52 and 2.1 ns, with almost equal preexponential factors. The fluorescence quencher CsCl does not affect the short lifetime but shifts the equilibrium between the long and short lifetime toward the short one and reduces the long lifetime. In nature, thynnine is found complexed with chromosomal DNA. In vitro complexes of thynnine with double‐stranded (ds) DNA are stable at physiologic ionic strength but dissociate at high NaCl concentration. This dissociation can be monitored by steady‐state fluorescence. From the salt concentration dependence of the dissociation of the complex of thynnine with ds‐DNA 145 bp long, it can be concluded that only 4 of 21 possible full electrostatic bonds are involved in thynnine‐DNA binding. In addition, the binding constant at 1M NaCl is of the order of 106, indicating a strong nonelectrostatic component in arginine‐DNA binding.
Tritium exchange of spectrin versus temperature
Authors: Bonnet D. , Begard Marden, E. , Hoa G. Hui Bon , Douzou P.
Published: July 2010

Tritium‐exchange experiments were performed to assess the dynamics of the spectrin molecule. From the kinetics presented, spectrin appears as a fast‐exchanging protein compared to globular proteins. This is easily explained by its known elongated structure. Spectrin tritium exchange is also shown to be highly temperature sensitive, even in buffer conditions that greatly reduce the temperature dependence of hydroxyl catalyst concentration. At high ionic strength, the exchange rates of specific hydrogens deduced from a power‐law simulation are shown to exhibit an Arrhenius behavior, with enthalpies ranging from 70 to 140 kjmol−1. These results are discussed in relation to the known high α‐helix content of spectrin. Finally, a molecular model of α‐helix opening is proposed that provides satisfactory agreement with the totality of the spectrin behavior in tritium‐exchange experiments.
Binding modules alter the activity of chimeric cellulases: Effects of biomass pretreatment and enzyme source
Authors: Kim Tae‐Wan , Chokhawala Harshal A. , Nadler Dana , Blanch Harvey W. , Clark Douglas S.
Published: July 2010

Improving the catalytic activity of cellulases requires screening variants against solid substrates. Expressing cellulases in microbial hosts is time‐consuming, can be cellulase specific, and often leads to inactive forms and/or low yields. These limitations have been obstacles for improving cellulases in a high‐throughput manner. We have developed a cell‐free expression system and used it to express 54 chimeric bacterial and archaeal endoglucanases (EGs), with and without cellulose binding modules (CBMs) at either the N‐ or C‐terminus, in active enzyme yields of 100–350 µg/mL. The platform was employed to systematically study the role of CBMs in cellulose hydrolysis toward a variety of natural and pretreated solid substrates, including ionic‐liquid pretreated Miscanthus and AFEX‐pretreated corn stover. Adding a CBM generally increased activity against crystalline Avicel, whereas for pretreated substrates the effect of CBM addition depended on the source of cellulase. The cell‐free expression platform can thus provide insights into cellulase structure‐function relationships for any substrate, and constitutes a powerful discovery tool for evaluating or engineering cellulolytic enzymes for biofuels production. Biotechnol. Bioeng. 2010;107:601–611. © 2010 Wiley Periodicals, Inc.
“Molded” rods of macroporous polymer for preparative separations of biological products
Authors: Svec Frantisek , Fréchet Jean M. J.
Published: July 2010

A continuous rod of porous poly(glycidy1 methacrylate‐co‐ethylene dimethacrylate) has been prepared by a free radical polymerization within the confines of a 16‐mm‐i.d. glass column. The epoxide groups of the rod have been modified in situ by their reaction with diethylamine to afford the ionizable weak base 1‐N,N‐diethylamino‐2‐hydroxypropyl functionalities that are required for the ion‐exchange chromatographic mode. The bimodal pore size distribution curve typical for other molded separation media also prevail for the preparative‐size rod. The column has been used successfully for the chromatographic separation of a mixture of standard proteins and yeast enzymes. The column exhibits a dynamic capacity that exceeds 420 mg of bovine serum albumin at a flow velocity of 60 cm/h. © 1995 John Wiley & Sons, Inc.
Interviewing children in custody cases: Implications of research and policy for practice
Authors: Saywitz Karen , Camparo Lorinda B. , Romanoff Anna
Published: July 2010

Research on child interviewing has burgeoned over the past 25 years as expectations about children's agency, competence, and participation in society have changed. This article identifies recent trends in research, policy, and theory with implications for the practice of interviewing children in cases of contested divorce and for the weight to be given the information children provide. A number of fields of relevant research are identified, including studies of families who have participated in the family law system, studies of child witnesses in the field, experimental studies of the effects of interview techniques on children's memory and suggestibility, and ethnographic methods that elicit children's views of their own experiences. Finally, a set of 10 principles for practice are delineated based on the best available science. Copyright © 2010 John Wiley & Sons, Ltd.
A morphometric study of the inferior orbital fissure using three‐dimensional anatomical landmarks: Application to orbital surgery
Authors: Ozer Mehmet Asim , Celik Servet , Govsa Figen
Published: July 2010

The inferior orbital fissure (IOF) is an important structure during orbital surgery, however, neither its anatomical features nor the procedures necessary to expose the IOF have been examined in detail. A morphometric analysis of the IOF was performed on 232 orbits using computer software. The longest and shortest borders of the IOF were 18.2 ± 4.9 and 1.9 ± 1.3 mm, respectively. The outer and the inner angles were 138.9 ± 32.7° and 38.4 ± 24.7°, respectively. The perimeter of the IOF was 50.6 ± 13.5 mm and its area was 61.3 ± 39.1 mm2. Eight types of IOF were observed. Type 1 IOF was observed in 42.2% and the Type 2 IOF was identified in 15.9%. A statistically significant relation was found between the longest edge and area and the widest edge and area of the IOF. The findings of our study suggest that the removal of the lateral wall should begin inferiorly, just lateral to the IOF and extended superolaterally. These data may be useful during surgical approaches to the orbit. Clin. Anat. 22:649–654, 2009. © 2009 Wiley‐Liss, Inc.
An interactive simulation tool for image registration education
Authors: Gharaibeh Khaled M. , Malkawi Mohammed J. , Hamza A. Ben
Published: July 2010

A medical image registration simulation toolkit built using MATLAB graphical user interface (GUI) is presented. The developed Matlab GUI's provide an effective tool for exploring different image registration techniques including a new feature‐based image registration technique proposed by the authors. The toolkit is useful for biomedical engineering students and can be used as a web‐based learning tool. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 225–237, 2010; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20179
Problem of computer programming education for technical engineers
Authors: Trontl Kresimir
Published: July 2010

When discussing the computer programming education at university level, one is usually focused on education of future computer science experts, while the computer education of technical engineers is put aside. Technical engineers are mostly trained in using commercial software specific for their area of expertise. However, due to somewhat extreme specialization and lack of commercial software, technical engineers are often encountered with the necessity of creating their own computer codes, whether by some basic “programming” in existing software like Excell or Access, or by hardcore programming in programming language of their choice. As a result of truly altruistic ideas, such software can usually be downloaded from World Wide Web (WWW), or obtained freely, directly from the creators. At that moment, the problems of computer programming education for technical engineers come to surface. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 200–202, 2010; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20187