bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acid‐Containing Tyrosine‐Derived Polycarbonates: Wettability and Surface Reactivity
Authors: Hoven Vipavee P. , Poopattanapong Adisorn , Kohn Joachim 
Published: October 2004

AbstractTyrosine‐derived polycarbonates having carboxylic acid pendant groups were characterized by water contact angle and X‐ray photoelectron spectroscopy (XPS). A pronounce decrease of receding angle as well as contact angle hysteresis as a function of acid composition strongly indicated that the acid groups are more accessible at the water/polymer interface after hydration. pH dependent contact angle confirmed an existence of carboxylic acid groups in the surface region. The receding angle transition appearing in the pH range of 4‐6 was a consequence of hydrophilicity change due to interconverting from carboxylic acid (‐COOH) to carboxylate ion (‐COO−). The surface compositions of imidazole‐labeled polymers as analyzed by XPS were consistent with the bulk stoichiometry of the polymers. Reactivity of acid groups towards chemical reaction at the surface was also investigated. The acid groups at the surface of polymers were capable of adsorbing a significant amount of calcium ion from simulated body fluid and being activated by a reaction with N‐hydroxysuccinimide.
Micromechanical Analysis of Thermoplastic – Thermoset Interphase
Authors: Vazquez‐Rodríguez J.M. , Herrera‐Franco P.J. , Gonzalez‐Chi P.I. 
Published: October 2004

AbstractThe interfacial shear strength of a pull out model between a thermoplastic fiber and thermoset matrix was analyzed. The method to analyze the interfacial quality in this kind of composite was Photoelasticity. The interfacial shear strength was measured localizing the isocromatic fringes. The Isochromatic fringe corresponds to the points along the specimen in which the principal stresses have the same value.
Spectroscopic Study of Di‐Imide Hydrogenation of Natural Rubber
Authors: Samran Jareerat , Phinyocheep Pranee , Daniel Philippe , Derouet Daniel , Buzare Jean‐Yves 
Published: October 2004

AbstractThe diimide hydrogenation of natural rubber (NR) was studied by using p‐toluenesulfonylhydrazide (TSH) as a diimide‐releasing agent. The microstructure and the percentage of hydrogenation were studied by Raman, 1H‐NMR and 13C‐NMR spectroscopic techniques. Quantitative measurements on fraction of hydrogenated part gave the results in good agreement by using these techniques. The results indicated that percent hydrogenation increased with increasing of reaction time and about 80‐85 % hydrogenation was achieved when a two‐fold excess of TSH was used. The vibrational characteristic of C=C bond of NR is strongly Raman active and noted at 1663 cm−1. The decrease of this signal was clearly observed during the progress of hydrogenation but the vibrational frequency of the cis and trans structures of the trisubstituted olefin unit of NR can not be differentiated by this technique. While 1H‐ and 13C‐NMR analysis showed that cis‐trans isomerization of carbon‐carbon unsaturation of NR occurred during hydrogenation.
Study on the Kinetics for Enzymatic Degradation of a Natural Polysaccharide, Konjac Glucomannan
Authors: Li Guangji , Qi Li , Li Aiping , Ding Rui , Zong Minhua 
Published: October 2004

AbstractThe enzymatic degradation of konjac glucomannan (KGM) was conducted using β‐mannanase from an alkalophilic Bacillus sp. in the aqueous medium (pH 9.0) at 30°C. The intrinsic viscosity ([η]), molecular weight (Mw) and molecular weight distribution (MWD) of the degraded KGM were measured. The mathematical relation between [η] and Mw, [η] = 5.06 × 10−4 Mw0.754, was established. The kinetic analysis reveals a dependence of the rate constant (k) on the period of reaction and the initial substrate concentration (c0) over the range of substrate concentration (1.0∼2.0%) used in this work. The results indicate that the enzymatic degradation of KGM is a complex reaction combining two reaction processes with different orders. In the initial phase of degradation k is inversely proportional to c0, which is characteristic of a zeroth‐order reaction; while in the following phase k is independent of c0, implying the degradation follows a first‐order reaction. The reactivity difference in breakable linkages of KGM, the action mechanism of an enzyme on KGM macromolecules, and the theory concerning the formation of an enzyme‐substrate complex and ‘substrate saturation’ can be used to explain such a kinetic behavior. In addition, the enzymatic degradation of KGM was also carried out using the other enzymes like β‐mannanase from a Norcardioform actinomycetes, β‐glucanase Finizym and a compound enzyme Hemicell as a biocatalyst. By comparing and analyzing the degradation processes of KGM catalyzed by four different enzymes, it can be observed that there is a two‐stage reaction with two distinct kinetic regimes over a certain range of degradation time for each of the degradation processes. These results are useful to realize controllable degradation of polysaccharides via an environmental benign process.
Investigations of Miscibility in Interpenetrated Systems of Polyurethane and Polystyrene Obtained at Room Temperature
Authors: Widmaier Jean‐Michel , Chenal Jean‐Marc 
Published: October 2004

AbstractInterpenetrating polymer systems based on crosslinked polyurethane (PU) and polystyrene (PS) were prepared at room temperature by a one‐shot (in situ) method, starting from an initial homogeneous mixture of reagents via non interfering mechanisms. Both polymerizations were performed either simultaneously or one after the other. Crosslinks and/or covalent bonds between components were deliberately introduced by the addition of appropriate monomers, in order to tailor the degree of microphase separation. Depending on the formation process, transluscent or transparent films were obtained, despite the difference in refractive index of the components. The maximum of miscibility, taken as from the glass transition criterion, was obtained for sequential tightly graft interpenetrating networks.
Rheological Behavior of Spinning Dope of Multiwalled Carbon Nanotube/Polyacrylonitrile Composites
Authors: Wang Biao , Li Jianmei , Wang Huaping , Jiang Jianming , Liu Yunqi 
Published: October 2004

AbstractThe spinning dope of Multiwalled carbon nanotube/polyacrylonitrile composites was prepared by in‐situ polymerization in 50wt% NaSCN solution. The rheological behavior of the dope containing carbon nanotubes from 0.19wt% to 1.9wt% was investigated using rotational rheometry at 60°C.The nanotubes have diameters between 30‐50nm and lengths ranging from 6 to 10 μm. The apparent viscosity decreases with the addition of carbon nanotubes; this can be explained by the inhibition of carbon nanotubes during polymerization progress. The spinning dope containing various contents of carbon nanotubes exhibits a shear thickening effect. However, the dynamic rheological test shows there is a peak of complex viscosity with the increasing in frequency.
Mathematical Analysis of the Formation of Molecule Sizes on a Spinning Disc Reactor
Authors: Novakovic Katarina , Morris Julian , Martin Elaine 
Published: October 2004

AbstractA mathematical analysis of the behaviour of the molecular weights of addition polymers during a polymerisation process is described. Spinning disc reactor (SDR) technology has been shown to yield significant improvements in terms of polymerisation rates whilst retaining close control of the molecular weights and the molecular weight distributions[1,2]. However, understanding of the kinetics of the polymerisation process on a SDR remains unresolved. One of the questions to be addressed concerns the sizes of the macromolecules preferably formed during the polymerisation process. To address this question, a mathematical analysis of the observed trends in number and weight average molecular weight, monomer concentration and polydispersity during the polymerisation process on a SDR has been undertaken. To validate the results, experimental data obtained from benzoyl peroxide initiated free radical polymerisation of styrene on a SDR[2] was used. It was concluded that most of the monomers consumed are in the growth of smaller size chains.
Preparation and Properties of Starch/Poly(vinyl alcohol) Composite Foams
Authors: Preechawong Dujdao , Peesan Manisara , Rujiravanit Ratana , Supaphol Pitt 
Published: October 2004

AbstractStarch/poly(vinyl alcohol) (PVA) composite foams were prepared by baking a mixture of starch, PVA, and other ingredients in a hot mold. The effects of relative humidity, storage period, PVA content, and type and content of plasticizer (e.g. glycerol, urea, or ammonium chloride) on moisture content, water absorption, mechanical properties, and biodegradability of the as‐prepared foams were investigated. In all of the testing conditions investigated, the ultimate tensile strength was shown to be a maximum when the relative humidity was 42%RH (for a fixed storage period of 7 days) and when the storage period was 2 days (for a fixed relative humidity of 42%RH). Addition of PVA improved the ultimate strength and the elongation at break of the composite foams. An increase in the amount of added plasticizer was responsible in an increase in the percentage of elongation at break at the expense of the tensile strength of the composite foams. Resistance to water absorption of starch/PVA composites foams was found to be superior to that of pure starch foams. Lastly, enzymatic degradation tests with α‐amylase showed that addition of PVA affected a little to the enzymatic degradability of the composite foams.
Structure and Properties of Biodegradable Polymer‐Based Blends
Authors: Qiu Zhaobin , Fujinami So , Komura Motonori , Nakajima Ken , Ikehara Takayuki , Nishi Toshio 
Published: October 2004

AbstractWe have recently investigated the structure and properties of biodegradable polymer based blends. The biodegradable polymers studied in our work include poly(3‐hydroxybutyrate) (PHB), poly(3‐hydroxybutyrate‐hydroxyvalerate) (PHBV), poly(butylene succinate) (PBSU), poly(ethylene succinate) (PES) and poly(ϵ‐caprolactone) (PCL). The miscibility, morphology, crystallization and melting behaviour of biodegradable polymer based blends have been studied extensively, which were reviewed briefly in this manuscript.
Effects of Compositions and Processing Variables on Barrier and Mechanical Properties of Liquid Crystalline Polymer/Polyethylene Blend Films
Authors: Trongsatitkul Tatiya , Aht‐Ong Duangdao , Chinsirikul Wannee 
Published: October 2004

AbstractCast films of liquid crystalline polymer (LCP) and low density polyethylene (LDPE) blends have been produced and investigated. Effects of LCP content and processing parameters, i.e., processing temperature profile, screw speed, and post‐die drawing, on morphology and O2 barrier property are presented. Increasing processing temperature and LCP content tend to enhance aspect ratios (L/D) of the LCP dispersed phase and at the same time influencing LCP structure. These effects are clearly observed when LCP content is increased from 10 % to 30 % by wt. At high temperature profiles, LCP morphologies are presented in a more or less ‘ribbon’ or ‘tape’ like structure together with a common LCP fibrillar structure. Films of 10% and 30% LCP produced at two optimum temperature profiles show a noticeable proportion of LCP tape‐like structure and interestingly high barrier properties of ∼1.6 and 5.5 times that of the neat LDPE films. High barrier characteristics of such LCP/PE blend films are indicated by low oxygen transmission rate values. Apart from processing temperature effect, increases of screw speed result in films having smaller aspect ratios for both LCP fibers and ribbons; films also exhibit poorer barrier and mechanical properties. However, post‐die drawing clearly demonstrates a positive effect in improving aspect ratios of the LCP domains and the resulting films' moduli. Effects of post‐die drawing on enhancing films' barrier properties become more pronounced at high LCP content. By comparing with the neat LDPE film (30 μm thick) having modulus of ∼180 MPa and OTR of ∼11000 cc/m2.day, the developed LCP/PE films containing 30 wt% LCP show remarkably high modulus values of ∼1100 MPa with low OTR of ∼2000 cc/m2.day.
Effects of Epoxidation Content of ENR on Morphology and Mechanical Properties of Natural Rubber Blended PVC
Authors: Jeerupun Jarunee , Wootthikanokkhan Jatuphorn , Phinyocheep Pranee 
Published: October 2004

AbstractThis research work has concerned a study on toughness of PVC/natural rubber (NR) blends compatibilized with epoxidized natural rubber (ENR). The aim of this work was to investigate the effect of degree of epoxidation on morphology and mechanical properties of the blends. Epoxidized natural rubber with a variety of epoxidation contents were prepared by reacting the NR latex with formic acid and hydrogen peroxide at various chemical contents. Chemical structure and epoxidation content of epoxidized natural rubber were evaluated by FTIR and 1H‐NMR techniques. After that, three grades of ENR with epoxidation contents of 15, 25 and 42 % (by mole) were further used for blending with PVC and NR in an internal mixer at 60 rpm and at 170 °C. From tensile and impact tests, it was found that tensile elongation and impact strength of the materials remarkably increased with degree of epoxidation. On the other hand, tensile strength and modulus of the materials rarely changed with the epoxidation content. An increase in toughness of the blends with epoxidation content was related to a better molecular interaction between PVC and ENR as suggested by torque‐time curves of the materials.
Effects of Solution Concentration, Emitting Electrode Polarity, Solvent Type, and Salt Addition on Electrospun Polyamide‐6 Fibers: A Preliminary Report
Authors: Mit‐uppatham Chidchanok , Nithitanakul Manit , Supaphol Pitt 
Published: October 2004

AbstractElectrospinning is a process by which ultrafine fibers which have diameters in the range of tens of nanometers to less than ten of micrometers can be produced. This process utilizes expulsion of charges as a means to very thin fiber formation. In this short report, the effects of some of the influencing solution and process parameters (i.e. solution concentration, emitting electrode polarity, solvent type, and salt addition) on morphological appearance of electrospun polyamide‐6 fibers were investigated based on visual observation of a series of scanning electron micrographs. It was found that all of the parameters studied played important roles in determining morphology and sizes of the fibers obtained.
Electrospun Non‐Woven Fabrics of Poly(ϵ‐caprolactone) and Their Biodegradation by Pure Cultures of Soil Filamentous Fungi
Authors: Ohkawa Kousaku , Kim Hakyong , Lee Keunhyung , Yamamoto Hiroyuki 
Published: October 2004

AbstractThe biodegradation of electrospun nano‐fibers of poly(ϵ‐caprolactone) was firstly investigated, using pure‐cultured soil filamentous fungi. In the biochemical oxygen demand test, the biodegradation of the nano‐fiber exceeded 20‐30% carbon dioxide generation. The biodegradabilities decrease with increase of the mean fiber diameter.
No global loss of neocortical neurons in parkinson's disease: A quantitative stereological study
Authors: Pedersen Kamilla M. , Marner Lisbeth , Pakkenberg Henning , Pakkenberg Bente 
Published: October 2004

AbstractThe global total number of neocortical neurons was estimated in 10 patients with Parkinson's disease (PD; mean age, 74.8 years; range, 68–83) and compared to 12 comparison subjects (mean age, 75.8 years; range, 70 – 84). The total mean neocortical neuron number in the patients with PD was 18.6 × 109 with a coefficient of variation (CV = SD/mean) of 0.18, which was not statistically significantly different from that of the controls (18.8 × 109; CV = 0.16; P = 0.90). In contrast to some studies reporting neocortical atrophy this was not confirmed in our study, where the mean volume of neocortex was the same in the two groups (P = 0.59). No difference was found in the volume of white matter, central gray structures, archicortex, or the ventricular system between the two groups. Most patients with PD develop cognitive disturbances with time, and this study cannot exclude that local neuron loss in specific subpopulations of neocortical neurons or cell loss in small but essential neocortical subregions may be part of the structural defects of PD. © 2004 Movement Disorder Society
High‐frequency characterization of coplanar waveguide and equivalent‐circuit modeling of interconnection for mini‐DIL package
Authors: Han Jae‐Ho , Jeong Jichai 
Published: October 2004

AbstractCoplanar‐waveguide transmission line is designed and characteristic impedance, return loss, and bandwidth are obtained for a mini‐DIL package. For microwave‐circuit simulation of the package, equivalent electric‐circuit modeling of die‐attached components with wire‐bonded interconnections is done and key parasitic elements influencing the scattering performance are extracted. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 365–367, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20470
Design of reflectarrays using slotted microstrip antennas with via connecting to ground plane
Authors: Meriah S. M. , Cambiaggio E. , Bendimerad F. T. , Staraj R. , Damiano J. P. 
Published: October 2004

AbstractThis paper proposes a new method for designing a microstrip‐antenna reflectarray. The array is a set of slotted rectangular microstrip antennas with one or two vias connected to the ground plane. Different techniques may be used to control the phase of the reflected wave, either by adjusting the via position along the symmetry axis of the patch (which is also the E‐field direction of polarization) or by adjusting the radius of the via. The reflection coefficient in terms of via characteristics is computed by a waveguide approach (WGA) using Agilent's High‐Frequency Structure‐Simulator (HFSS) software. Three 1 × 18 elements reflectarrays in the X‐band have been designed, realized, and tested. The measured reflectarray radiation patterns show that the main‐beam steering agrees with the design requirements. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 368–370, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20471
TM010 dielectric loaded cavity resonator for microwave filter
Authors: Wang Jian , Liu Pitao , Li Ying 
Published: October 2004

AbstractThis paper describes a type of rectangular dielectric‐loaded cavity resonator based on TM010 mode. The resonator has an unloaded quality factor (Q) of about 10,000 and good spurious‐free performance and is suitable for the design of multiple cavity microwave filters. We present two sample filters using this kind of resonator. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 373–376, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20473
On the benefits of multifiber optical packet switch
Authors: Li Yi , Xiao Gaoxi , Ghafouri‐Shiraz H. 
Published: October 2004

AbstractIn this paper, we study the benefits of using multiple fibers per link in optical packet‐switched networks. The node architecture is presented and various contention resolution schemes are evaluated. Comparisons are made between the multifiber switch with a small number of wavelengths per fiber and the traditional single‐fiber switch with a large number of wavelengths per fiber. The analytical and simulation results show that although the multifiber switch cannot easily perform as well as a switch with full wavelength conversion, compared to the traditional switch, it significantly reduces the number of wavelength converters and fiber delay lines while achieving a lower packet‐loss rate. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 376–378, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20474
A method to obtain the isothermal static DC curves of microwave FET power amplifiers
Authors: Torregrosa‐Penalva G. , Asensio‐López A. , Blanco‐del‐Campo A. 
Published: October 2004

AbstractThis paper proposes a method to obtain the isothermal static DC curves of microwave FET power amplifiers, avoiding the use of pulsed measurements and accounting for the self‐heating problem in this type of device. The method requires the determination of the thermal resistance of the device under test and the measurement of its static DC curves under different ambient temperatures. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 378–380, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20475
Ultra‐wideband metal‐plate monopole antenna for laptop application
Authors: Wong Kin‐Lu , Chou Liang‐Che , Chen Hong‐Twu 
Published: October 2004

AbstractThis paper presents a study of an ultra‐wideband (UWB) metal‐plate monopole antenna applied to a laptop for wireless communications. The UWB antenna in this study is a metal‐plate monopole of an inverted‐L shape mounted at the top edge of the supporting metal frame for the laptop display. The UWB antenna shows an operating bandwidth of about 4.5 GHz (1890–6450 MHz), so that it easily cover the UMTS band (1920–2170 MHz) for mobile communication and the 2.4‐GHz (2400–2484 MHz) and 5.2/5.8‐GHz (5150–5350/5725–5875 MHz) bands for WLAN communication. That is, the UWB antenna studied is suitable for application in a laptop capable of UMTS/WLAN dual‐mode operation for wireless Internet access. The radiation characteristics for frequencies across the UMTS and WLAN bands are also presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 384–386, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20478
Beam switching and scattering analysis for a microwave hologram modeled by disk lattices with transversely modulated sizes
Authors: Zhu Wenhao , McNamara Derek A. , Shaker Jafar 
Published: October 2004

AbstractThe scattering from a microwave volume hologram made of layered 2D printed disk lattices is analyzed based on the dynamic interaction theory between small metallic disks and fields. The planar disk lattice has its disk size varying periodically in one direction (x) while remaining uniform in the other direction (y) to simulate a 1D holographic grating. The transmitted and reflected fields under TE plane‐wave incidence are obtained in closed form. Beam switching can be achieved with a volume hologram thus implemented and the switching angle can be controlled by the slant angle of the grating with respect to the hologram's normal. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 390–394, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20480
1 × 3 wavelength demultiplexer based on multimode interference with an index‐modulation region
Authors: Sam Y. L. , Won Y. H. 
Published: October 2004

AbstractWe propose a novel structure for a compact 1 × 3 wavelength demultiplexer with an index‐modulation region incorporated into a multimode interference coupler. We can have an extra output port with a simple device structure. The performance of this device has been enhanced by changing the phase within the region. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 400–403, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20482
Mutual‐coupling decomposition in antenna arrays
Authors: Letestu Y. , Mahdjoubi K. , Sharaiha A. 
Published: October 2004

AbstractIn this paper, a method to evaluate array patterns is presented. This method considers all the mutual‐coupling effects, and assumes that the field of an element is the sum of two distinct modes: an antenna mode and a diffraction mode. Good results are obtained for a finite linear‐dipole array. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 403–406, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20483