bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and evaluation of a nanocomposite of polythiophene with Al2O3
Authors: Ballav Nirmalya , Biswas Mukul
Published: January 2003

The polymerization of thiophene (TP), in bulk and in solution in CHCl3 by FeCl3 resulted in the formation of a polymer which was characterized by FTIR as polythiophene (PTP). High yield was realized in the latter case. The polymerization of TP with FeCl3 and nanodimensional Al2O3 resulted in the formation of a nanocomposite which was partly dispersible in aqueous and non‐aqueous media. The dispersibility appeared to be higher when the polymerization was conducted in a suspension containing a higher amount of Al2O3. Scanning electron micrographs showed globular particles and the presence of clusters of composite particles. Transmission electron micrographic (TEM) analyses revealed the particle size of the composite to be in the range 22–74 nm. Thermal analyses (TG/DTA) revealed the outstanding stability of PTP–Al2O3 composites compared to that of PTP. The conductivity of PTP and of PTP–Al2O3 composite was of the order of 10−3 S cm−1 for samples doped with I2.

© 2003 Society of Chemical Industry
Ultrasonic improvement of rheological and processing behaviour of LLDPE during extrusion
Authors: Guo Shaoyun , Li Yuntao , Chen Guangshun , Li Huilin
Published: January 2003

The effects of ultrasonic oscillations on die pressure, productivity of extrusion, melt viscosity and melt fracture of linear low density polyethylene (LLDPE) as well as their mechanism of action were studied in a special ultrasonic oscillation extrusion system developed in our Laboratory. The experimental results showed that, in the presence of ultrasonic oscillations, the melt fracture or surface distortion of LLDPE extrudate is inhibited or disappears. The surface appearance of the LLDPE extrudate was greatly improved. The productivity of LLDPE extrudate was increased in the presence of ultrasonic oscillations. The die pressure, melt viscosity and flow activation energy of LLDPE decreased with the rise in ultrasonic intensity. The shear sensitivity of LLDPE melt viscosity decreased due to the increase of its power law index in the presence of ultrasonic oscillations. Inducing ultrasonic oscillations into LLDPE melt greatly improved its processability. A possible mechanism for the improved processibility is proposed.

© 2003 Society of Chemical Industry
Fireproofing of polyurethane elastomers by reactive organophosphonates
Authors: El Khatib Wassef , Youssef Boulos , Bunel Claude , Mortaigne Bruno
Published: January 2003

Polyurethane elastomers were prepared with hydroxytelechelic polybutadiene (HTPB) as polyol, modified 4,4′‐diphenylmethane diisocyanate (modified MDI) as liquid polyisocyanate, and phosphonate diols as chain extenders and flame retardant compounds. These phosphonate diols were synthesized by radical thiol–ene addition of allyl or vinyl dialkyl phosphonate to 3‐mercapto‐1,2‐propanediol. For various percentages of phosphorus (0 to 3%, w/w), polyurethane elastomers remain stable up to 250 °C. The percentage of residual char at 600 °C increases with increasing phosphorus content. For the soft segments, no variation in the glass transition temperature (Tg) is observed as the percentage of P increases, whereas the Tg of hard segments increases. Above 0.5% phosphorus content, the limiting oxygen index (LOI) becomes higher than the percentage of oxygen in the air.

© 2003 Society of Chemical Industry
Thermal analysis, glass transition temperature and rheological behaviour of emulsion copolymers of methyl methacrylate with styrene
Authors: Zhang Liucheng , Liu Guodong , Ji Rongqin , Yao Yanmei , Qu Xiongwei , Yang Liting , Gao Jungang
Published: January 2003

Poly(MMA‐ran‐St) samples were synthesized under monomer‐starved conditions (drop feeding method) by emulsion copolymerization. Their thermostability was determined by thermogravimetric analysis. The glass transition temperature (Tg) of the copolymers was determined by differential scanning calorimetry (DSC) and torsional braid analysis (TBA). The results showed that the MMA–St copolymers exhibit an asymmetric Tg versus composition curve, which could not be interpreted by Johnston's equation, taking the different contributions of the diads to the Tg of the copolymer into consideration. A new sequence distribution equation taking into account the different contributions of the triads was proposed to predict the copolymer Tg. The new equation fitted the experimental data exactly. The Tg determined by torsional braid analysis (TBA) is higher than the one determined by DSC, but the difference is not constant. The rheological behaviour of the copolymers was also studied and TgTBA‐TgDSC increased with the increasing flow index of the copolymer.

© 2003 Society of Chemical Industry
Preparation and blood compatibility of phosphorylcholine‐bonded O‐butyrylchitosan
Authors: Zhu Aiping , Shan Bing , Yuan Youling , Shen Jian
Published: January 2003

2‐Methacryloyloxyethyl phosphorylcholine (MPCE) was synthesized using phosphorus trichloride, ethylene glycol, 2‐hydroxyethyl methacrylate and triethylamine, and then used in the preparation of O‐butyrylchitosan‐bonded MPCE (MPCE–BCS) by Michael addition of MPCE to amino groups of O‐butyrylchitosan. The structures of MPCE and MPCE–BCS were characterized by FTIR and 1H NMR. The blood‐compatibility of MPCE–BCS was evaluated by means of blood clotting and platelet adhesion assays. The blood‐clotting assay indicated that O‐butyrylchitosan was haemocompatible. Both the blood‐clotting assay and platelet adhesion assay confirmed that MPCE–BCS had excellent antithrombogenicity.

© 2003 Society of Chemical Industry
Study by thermal analysis of composites prepared from silica gel, furfuryl alcohol and acetaldehyde
Authors: García Teresita de la C , Gómez Maria R , Martínez Ricardo , Alonso Cristina
Published: January 2003

Composites from furfuryl alcohol, acetaldehyde and silica gel were prepared with trifluoracetic acid as a catalyst. The composites were studied by TGA and DSC. The TGA results showed three main losses of weight, the first of which was ascribed to water. The percentage of polymer in the composites reached a limit value, independently of the ratio of furfuryl alcohol/acetaldehyde used. The layer of polymer that covers the silica was not completely cross‐linked. The composites contain soluble oligomers with 97: M
n < 580 g mol−1, that could be extracted with THF. The soluble fraction of composites prepared from mixtures of furfurylic alcohol and acetaldehyde decreased as the proportion of the acetaldehyde increased. The DSC of the samples indicated a Tg between −8 and −15 °C that disappeared after an extraction with THF. The DSC of the oligomers removed showed a possible Tg at 13 °C and an exothermic peak between 70 and 170 °C which corresponded to an enthalpy of 326.1 J g−1.

© 2003 Society of Chemical Industry
Synthesis and characterization of novel rod–coil diblock copolymers of poly(methyl methacrylate) and liquid crystalline segments of poly(2,5‐bis[(4‐methoxyphenyl)oxycarbonyl] styrene)
Authors: Zhang Hai‐Liang , Chen Xiaofang , Wan Xinhua , Zhou Qi‐Feng , Woo E M
Published: January 2003

Liquid crystalline diblock copolymers with different molecular weights and low polydispersities were synthesized by atom transfer radical polymerization of methyl methacrylate (MMA) and 2,5‐bis[(4‐methoxyphenyl)oxycarbonyl]styrene (MPCS) monomers. The block architecture (coil‐conformation of MMA segment and rigid‐rod of MPCS segment) of the copolymer was experimentally confirmed by a combination of 1H nuclear magnetic resonance and gel permeation chromatograph techniques. The liquid crystalline behaviour of the copolymer was studied using differential scanning calorimetry and polarized optical microscope. It was found that the liquid crystalline behaviour was dependent on the number average molecular weight of the rigid segment. Only those copolymers with Mn(GPC) of the rigid block above 9200 g mol−1 could form liquid crystalline phases higher than the glass transition temperature of the rigid block. The random copolymers MPCS‐co‐MMA were also synthesized by conventional free radical polymerization. The molar content of MPCS in MPCS‐co‐MMA had to be higher than 71% to maintain liquid crystalline behaviour.

© 2003 Society of Chemical Industry
Crystallization and morphology of metallocene polyethylenes with well‐controlled molecular weight and branching content
Authors: Peng Ya , Fu Qiang , Chiu Fang‐Chyou
Published: January 2003

The crystallization and morphology of some metallocene polyethylenes with well‐controlled molecular weight and branching content were investigated by DSC, WAXD, PLM and SALS. The banded spherulites observed in linear PE are not seen in crystallization of branched PEs. The small spherulites with small lamellae or fringed micelle crystals are formed when branching content is higher, as suggested by PLM and SALS. The expansion of the unit cell was observed by WAXD as the molecular weight and branching content increased. At even higher branching content (more than 7 mol%), a shrinkage of the unit cell was seen, probably due to a change of crystal morphology from lamellar‐like crystals to fringed micelle‐like crystals. Crystallization temperature, melting point and crystallinity are greatly decreased for branched PEs compared with linear PEs. The equilibrium melting temperature cannot be determined via the Hoffman–Weeks approach for branched PEs since Tm is always 5–6 °C higher than Tc and there is no intercept with the Tm = Tc line. Our results show a predominant role of branches in the crystallization of polyethylene.

© 2003 Society of Chemical Industry
Study on controlled radical alternating copolymerization of styrene with maleic anhydride under UV irradiation
Authors: Wu De‐Cheng , Hong Chun‐Yan , Pan Cai‐Yuan , He Wei‐Dong
Published: January 2003

The copolymerization of styrene with maleic anhydride (MAh) in the presence of 1‐(ethoxycarbonyl)prop‐1‐yl dithiobenzoate was carried out under UV irradiation at room temperature, and showed ‘living’ polymerization nature which was evidenced by: linear evolution of molecular weight with conversion; and narrow molecular weight distribution (Mw/Mn = 1.08–1.20). The compositional analysis and the sequence structural information of the copolymer obtained from Distortionless Enhancement by Polarization Transfer (DEPT) NMR experiments demonstrated that the copolymers obtained possess strictly alternating structure.

© 2003 Society of Chemical Industry
New aspects of unsaturated polyester resin synthesis. Part I: modelling and simulation of reactant sequence length distributions in stepwise polymerization
Authors: Zetterlund Per B , Gosden Ray G , Johnson Anthony F
Published: January 2003

The quantification of the relationship between physical properties of polymeric products and the sequence distribution of comonomer units in a polymer chain is not an easy task. In this work, detailed consideration is given to the sequence lengths and sequence length distributions to be expected in unsaturated polyesters formed by the reaction of maleic anhydride, phthalic anhydride and a diol, a reaction which gives rise to the low molecular weight precursors used in unsaturated polyester resins. Monte Carlo methods are used to explore the effects of rate constants, reactant stoichiometry and extent of reaction on the microstructure of the chain. Attention is also given to structural asymmetry of the diol component and the influence of the dynamics of the ring opening of the anhydride coreactants on the products. The approach is generic and can be readily adapted for any copolymerization which proceeds by a stepwise kinetic mechanism.

© 2003 Society of Chemical Industry
The effects of fillers on the chemorheology of highly filled epoxy resins: I. Effects on cure transitions and kinetics
Authors: Altmann Nara , Halley Peter J
Published: January 2003

This work examines the effects of level of silica filler (at 0, 10, 30, 50 wt%) on the gelation and vitrification of a model silica‐filled diglycidyl ether of bisphenol F (DGEBF)/methylenedianiline (MDA) system. An increased filler level is shown to decrease the gelation and vitrification times at low temperatures (below 80 °C). FTIR cure kinetics show that the reaction rates are increased and the activation energies of gelation are reduced at these temperatures, indicating that network formation is made easier. Entropic and catalytic reasons for this phenomenon are discussed.

© 2003 Society of Chemical Industry
Rheological and mechanical properties of dynamically cured poly(vinyl chloride)/nitrile butadiene rubber thermoplastic elastomers
Authors: Mousa A , Ishiaku U S , Ishak Z A Mohd
Published: January 2003

Plasticized poly(vinyl chloride)/nitrile butadiene rubber (PVC/NBR) thermoplastic elastomers (TPEs) were dynamically cured in the melt stage with the incorporation of a semi‐efficient curing system using a Brabender Plasticorder at 150 °C and rotor speed of 50 rev min−1. Sulfur concentration was progressively increased from zero to 1 part per hundred NBR to study the effect of dynamic curing on mechanical and rheological behaviour of the TPEs. The compounds were characterized in respect of their rheological and mechanical properties. The effectiveness of dynamic curing was studied using Brabender plastograms, a moving disc rheometer and swelling index measurement. The mechanical properties investigated include tensile strength, elongation at break, modulus at 100% elongation, tear strength and hardness. The influence of thermooxidative ageing on the mechanical properties was investigated by incubating the PVC/NBR TPEs in an air oven at 80 °C for 168 h. The torque values obtained from both rheometers increased with increasing sulfur dosage, while the swelling index decreased. The significant increase in the degree of curing evidenced by the steady reduction in the swelling index provided excellent proof of the efficiency of the dynamic curing technique. Thermo‐oxidative ageing resulted in a pronounced enhancement in mechanical properties as a function of sulfur content. This observation seems to indicate that some microstructural changes, such as the formation of new crosslinks, occur in the thermo‐oxidatively aged TPEs. This trend was supported by further reduction in the swelling index of the aged TPEs.

© 2003 Society of Chemical Industry
New soybean oil–styrene–divinylbenzene thermosetting copolymers. VI. Time–temperature–transformation cure diagram and the effect of curing conditions on the thermoset properties
Authors: Li Fengkui , Larock Richard C
Published: January 2003

A new class of thermosetting resins has been developed that is based on the cationic copolymerization of regular soybean oil (SOY), low saturation soybean oil (LSS), or conjugated LSS (CLS) with various alkene comonomers initiated by boron trifluoride diethyl etherate (BFE) or related modified initiators. The activation energy for the gelation process for these thermosets ranges from 95 to 122 kJ/mol. A time‐temperature‐transformation (TTT) isothermal cure diagram has been established for the model system LSS45–ST32–DVB15–(NFO5–BFE3) ie 45 wt% low saturation soybean oil, 32 wt% styrene, 15 wt% divinylbenzene, and 5 wt% Norway fish oil ethyl ester plus 3 wt% boron trifluoride diethyl etherate. The effect of curing conditions on the thermophysical and mechanical properties, including the mechanical damping and shape memory properties, has been subsequently investigated using this model thermoset. These findings allow the efficient optimization of desired properties for specific applications.

© 2003 Society of Chemical Industry
Preparation and characterization of ethylene vinyl acetate copolymer/montmorillonite nanocomposite
Authors: Jeon Cheol Hwan , Ryu Sung Hun , Chang Young‐Wook
Published: January 2003

Ethylene vinyl acetate copolymer (EVA) and monmorillonite (MMT) nanocomposites have been investigated as a function of vinyl acetate content and molecular weight of EVA and types of substituted alkyl ammonium of MMT. It is found that vinyl acetate content and type of substituted alkyl ammonium are important factors for the intercalation behaviour of MMT in MMT/EVA nanocomposite. Maleic anhydride grafted high‐density polyethylene was used as a compatibilizer to improve the intercalation behaviour of MMT. X‐ray diffraction and transmission electron microscopy were used to characterize the intercalation/exfoliation behaviour, and mechanical properties were measured.

© 2003 Society of Chemical Industry
Properties of PP/PET bicomponent melt blown microfiber nonwovens after heat‐treatment
Authors: Zhao Ron (Rongguo) , Wadsworth Larry C , Sun Christine , Zhang Dong
Published: January 2003

Polypropylene (PP)/poly(ethylene terephthalate) (PET) bicomponent (bico) fibres are successfully melt blown in the Reicofil® meltblown (MB) pilot line commissioned at the Textiles and Nonwovens Development Center (TANDEC), the University of Tennessee, Knoxville. The bico fibers possess a cross‐sectional side‐by‐side configuration. The originally expected greater fiber crimp due to density and fine structure gradients on the different sides of the bico fibers was not commonly observed in the normal MB webs. These fabrics were exposed to dry heat for a period of time. The properties before and after the heat treatment were determined and compared to investigate the effects of heat on their properties. It was found that the bico webs are thermal dimensionally stable and many of their properties were not significantly affected. A mechanism is suggested on the thermal dimensional stability of the PP/PET bico MB webs.

© 2003 Society of Chemical Industry
Studies on cellulose acetate–carboxylated polysulfone blend ultrafiltration membranes—Part II
Authors: Sajitha C J , Mohan D
Published: January 2003

Hydrophilic polysulfone ultrafiltration membranes were prepared from blends of cellulose acetate and carboxylated polysulfones of 0.43 and 0.75 degrees of carboxylation. The effects of degree of carboxylation on membrane characteristics such as compaction, pure water flux, water content and membrane hydraulic resistance, have been investigated to evaluate the performance of the membranes. The influence of the degree of carboxylation on the performance of the blend membranes of various blend polymer compositions has been investigated and also compared with earlier reports on blend membranes prepared from cellulose acetate and polysulfone or carboxylated polysulfone of 0.14 degree of carboxylation.

© 2003 Society of Chemical Industry
Primary amine functionalized polystyrenes by atom transfer radical polymerization
Authors: Summers Gabriel J , Ndawuni Mzikayise P , Summers Carol A
Published: January 2003

Primary amine functionalized polystyrenes were prepared in quantitative yields by atom transfer radical polymerization using the adduct of 1‐(bromoethyl)benzene with 1‐(4‐aminophenyl)‐1‐phenylethylene as initiator for styrene polymerization in the presence of a copper(I) bromide/N,N,N′,N′,N″‐pentamethyldiethylenetriamine catalyst system. The polymerizations proceeded via a controlled free radical polymerization process to afford quantitative yields of the corresponding primary amine functionalized polystyrenes with predictable molecular weights (Mn = 2 × 103 to 10 × 103 g mol−1), relatively narrow molecular weight distributions (Mw/Mn = 1.03–1.49), well defined chain‐end functionalities and initiator efficiencies as high as 0.92. The polymerization process was monitored by gas chromatographic analysis. The primary amine functionalized polymers were characterized by thin layer chromatography, size exclusion chromatography, potentiometry and spectroscopy. Experimental results are consistent with quantitative functionalization via the 1,1‐diphenylethylene derivative. Polymerization kinetic measurements show that the polymerization reaction follows first order rate kinetics with respect to monomer consumption and the number average molecular weight increases linearly with monomer conversion.

© 2003 Society of Chemical Industry
Thermal degradation study of interpenetrating polymer network based on modified bismaleimide resin and cyanate ester
Authors: Fan Jing , Hu Xiao , Yue Chee Yoon
Published: January 2003

Interpenetrating polymer networks (IPNs) based on different ratios of a modified bismaleimide resin (BMI/DBA) and cyanate ester (b10) have been synthesized via prepolymerization followed by thermal curing. A systematic thermal degradation study of these new BMI/DBA‐CE IPN resin systems was conducted by thermogravimetric analysis at different heating rates both in N2 (thermal stability) and in air (thermal‐oxidative stability). The cured BMI/DBA‐CE IPN resin systems show excellent thermal stability, which could be demonstrated by 5% weight loss temperature (T5%) ranging between 409 and 423 °C, maximum decomposition rate temperature (Tmax) ranging between 423 and 451 °C, and the char yields at 800 °C ranging from 37% to 41% in nitrogen at a heating rate of 10 °C min−1. The apparent activation energy associated with the main degradation stage of the cured BMI/DBA‐CE IPN resin systems was determined using the Kissinger method. The obtained results provide useful information in drawing correlation between thermal properties and structure.

© 2003 Society of Chemical Industry
Stepwise polymerization of propylene and ethylene with Cr(acetylacetonate)3/MgCl2–ethylbenzoate/diethylaluminium chloride catalyst system
Authors: Shin Yong‐Woo , Nakatani Hisayuki , Uozumi Toshiya , Liu Boping , Sano Tsuneji , Nitta Koh‐hei , Terano Minoru
Published: January 2003

During propylene polymerization with the Cr(acetylacetonate)3/MgCl2–Et2AlCl–ethylbenzoate catalyst system which shows high isospecificity for propylene polymerization, it was found that the chain transfer and termination reactions can be neglected. Based on this result, some stepwise polymerizations of propylene and ethylene were carried out with the same catalyst system varying polymerization conditions. The resulting copolymers were separated by temperature rising elution fractionation (TREF) and afforded two fractions which were eluted at different temperatures. From the 13C NMR, DSC and GPC analyses of each fraction, it was considered that the corresponding block copolymer existed in the fraction eluted at higher temperature.

© 2003 Society of Chemical Industry
Effects of La3+‐containing additive on crystalline characteristics of isotactic polypropylene
Authors: Feng Jiachun , Chen Mingcai
Published: January 2003

The influence of a mixed additive of lanthanum stearate and stearic acid on the crystalline characteristics of isotactic polypropylene (iPP) has been investigated. The results of the wide‐angle X‐ray diffraction (WAXD) measurements and the melting behaviour examination by differential scanning calorimetry (DSC) show that the additive might induce a high proportion of β‐form and act as a β‐form nucleating agent. The relative content of β‐form estimated by WAXD is 33.1% in a PP containing 2.5% (by weight) of the additive. Isothermal crystallization at 130 °C, examined by DSC, reveals that the additive considerably accelerates the overall rate of crystallization: the half crystallization period t1/2, decreases from 11.7 min for pure PP to 7.3 min for PP containing 2.5% of the additive. However, the additive has no obvious influence on the nucleation mechanism and crystal growth mode. Polarized light microscopy (POM) examinations indicate that the addition of the additive to PP causes spherulites to become much finer.

© 2003 Society of Chemical Industry
Comparative structural studies of poly(heptamethylene p,p′‐bibenzoate) by X‐ray diffraction, positron annihilation and microhardness
Authors: Zamfirova Galina , Krasteva Manya , Misheva Marijka , Mihaylova Milena , Pérez Ernesto , Pereña José M
Published: January 2003

The structure of quenched samples of a polybibenzoate with a spacer containing seven methylene units has been studied by wide angle X‐ray scattering (WAXS), microhardness (MH) methods and positron annihilation lifetime spectroscopy (PALS). It was established that the quenched samples of poly(heptamethylene p,p′‐bibenzoate) (P7MB) contain three phases simultaneously: smectic liquid crystalline, amorphous, and a small amount of crystalline one. The d‐spacing of the crystal peaks, together with the crystal and smectic domain dimensions in the direction normal to the mesogen planes and the factor of paracrystallinity, were calculated. The average distance between macromolecules determined from the position of the amorphous halo correlates with the open pore diameter obtained by the PALS analysis. On the basis of MH measurements it was considered that the phases are not uniformly distributed in the depth of the sample, so that the smectic phase prevails in the surface layer while the inner layers are partially crystalline.

© 2003 Society of Chemical Industry
Recovery of gold cyanide using inherently conducting polymers
Authors: Ding Jie , Price William E , Ralph Stephen F , Wallace Gordon G
Published: January 2003

Removal of gold from basic solutions containing [Au(CN)2]− has been demonstrated using the inherently conducting polymer polypyrrole. Polymers containing sulfonated aromatic dopants have been found to display a significant ability to remove gold from such solutions. Experiments performed in solutions containing both gold and copper cyanide complexes indicate that the recovery process is not highly selective. However, the polypyrroles used display significantly faster rates of gold recovery than activated carbon.

© 2003 Society of Chemical Industry
Novel pH, ion sensitive polyampholyte gels based on carboxymethyl chitosan and gelatin
Authors: Chen Lingyun , Du Yumin , Huang Ronghua
Published: January 2003

Natural pH and ion sensitive polyampholyte gels were successfully prepared by blending carboxymethyl chitosan (CM‐chitosan) and gelatin using glutaraldehyde as crosslinking agent. Their swelling behaviour under the influence of pH and ionic strength of the solution has been studied, and molecular interaction and, morphology of the gels were investigated by infrared spectroscopy and scanning electron microscopy. At the isoelectric point (IEP) the blend gels shrunk most, and when pH deviated from the IEP they behaved as polycations or polyanions. A decrease in swelling degree (Ds) with rising NaCl concentration up to 0.15 M was observed for all gels, while addition of Ca2+ made them shrink due to formation of Ca2+ crosslinked bridges. The blended gels showed increasing sensitivity to pH and ionic strength as the weight fraction of CM‐chitosan increased. Two essential components seem to regulate the swelling behaviour of blended gel: the first is related to osmotic pressure difference caused by the redistribution of mobile ions; the second is related to the possible formation of interactions corresponding to hydrogen bonding and hydrophobic interactions.

© 2003 Society of Chemical Industry
The aspartimide problem in Fmoc‐based SPPS. Part I
Authors: Mergler M. , Dick F. , Sax B. , Weiler P. , Vorherr T.
Published: January 2003

A variety of Asp β‐carboxy protecting groups, Hmb backbone protection and a range of Fmoc cleavage protocols have been employed in syntheses of the model hexapeptide H‐VKDGYI‐OH to investigate the aspartimide problem in more detail. The extent of formation of aspartimide and aspartimide‐related by‐products was determined by RP‐HPLC. This study included three new Fmoc‐Asp‐OH derivatives: the β‐(4‐pyridyl‐diphenylmethyl) and β‐(9‐phenyl‐fluoren‐9‐yl) esters and also the orthoester Fmoc‐β‐(4‐methyl‐2,6,7‐trioxabicyclo[2.2.2]‐oct‐1‐yl)‐alanine. 3‐Methylpent‐3‐yl protection of the Asp side chain resulted in significant improvements with respect to aspartimide formation. Complete suppression was achieved using the combination OtBu side chain protection and Hmb backbone protection for the preceding Gly residue. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
HRMAS NMR observation of β‐sheet secondary structure on a water swollen solid support
Authors: Rousselot‐Pailley Pierre , Boutillon Christophe , Wieruszeski Jean‐Michel , Lippens Guy
Published: January 2003

In this paper HRMAS NMR was used to investigate whether peptides on a peptidyl resin swollen in aqueous solution can adopt an intramolecular β‐sheet structure. A model peptide YQNPDGSQA, that was previously shown to adopt such a secondary structure in solution, (Blanco et al., J. Am. Chem. Soc., 1993) was grafted onto three different solid supports that swell in aqueous solution to examine the influence of the resin on the structure. Both parameters of resin loading and pH inside the swollen peptidyl resin proved to be important for the physicochemical behaviour of the peptide on the support. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Role of a two‐residue spacer in an α,β‐didehydrophenylalanine containing hexapeptide: crystal and solution structure of Boc‐Val‐ΔPhe‐Leu‐Ala‐ΔPhe‐Ala‐OMe
Authors: Padyana Anil K. , Ramakumar S. , Mathur Puniti , Jagannathan N. R. , Chauhan V. S.
Published: January 2003

The peptide Boc‐Val1‐ΔPhe2‐Leu3‐Ala4‐ΔPhe5‐Ala6‐OMe has been examined for the structural consequence of placing a two‐residue segment between the ΔPhe residues. The peptide is stabilized by four consecutive β‐turns. The overall conformation of the molecule is a right‐handed 310‐helix, with average (ϕ, ψ) values (−67.7°, −22.7°), unwound at the C‐terminus. The 1H NMR results also suggest that the peptide maintains its 310‐helical structure in solution as observed in the crystal state. The crystal structure is stabilized through head‐to‐tail hydrogen bonds and a repertoire of aromatic interactions laterally directed between adjacent helices, which are antiparallel to each other. The aromatic ring of ΔPhe5 forms the hub of multicentred interactions, namely as a donor in aromatic C–H···π and aromatic C–H···OC interactions and as an acceptor in a CH3···π interaction. The present structure uniquely illustrates the unusual capability of a ΔPhe ring to host such concerted interactions and suggests its exploitation in introducing long‐range interactions in the folding of supersecondary structures. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Conformational investigation of α, β‐dehydropeptides. XI. Molecular and crystal structure of Ac‐(Z)‐ΔPhe‐NMe2 as compared to those of related molecules
Authors: Siodłak Dawid , Broda Małgorzata A. , Rzeszotarska Barbara , Dybała Izabela , Kozioł Anna E.
Published: January 2003

A series of three homologous dimethyldiamides Ac‐(Z)‐ΔPhe‐NMe2, Ac‐L‐Phe‐NMe2 and Ac‐DL‐Phe‐NMe2 have been synthesized and their structures determined from single‐crystal X‐ray diffraction data. To learn more about the conformational preferences of the compounds studied, the fully relaxed ϕ, ψ conformational energy maps on the free molecules of Ac‐ΔAla‐NMe2 and Ac‐(Z)‐ΔPhe‐NMe2 were obtained with the HF/3‐21G method and the calculated minima re‐optimized with the DFT/B3LYP/6‐31G** method. The crystal state results have been compared with the literature data. The studied dimethyldiamide Ac‐ΔXaa‐NMe2 combines the double bond in positions α, β and the C‐terminal tertiary amide within one molecule. As the representative probe with ΔXaa = ΔAla, (Z)‐ΔLeu and (Z)‐ΔPhe shows, in the solid state they adopt the conservative conformation with ϕ, ψ∼ −45°, ∼130° and with a non‐planar tertiary amide bond, whatever the packing forces are. This conformation is located on the Ramachandran map in region H/F, which is of high‐energy for common amino acids, but not so readily accessible to them. The free molecule calculations on Ac‐ΔAla‐NMe2 and Ac‐(Z)‐ΔPhe‐NMe2 reveal that, in spite of dissimilar overall conformational profiles of these molecules, this structure is one of their low‐energy conformers and for Ac‐(Z)‐ΔPhe‐NMe2 it constitutes the global minimum. So, the theoretical results corroborate those experimental results proving that this structure is robust enough to avoid conformational distortion due to packing forces. In contrast to Ac‐ΔXaa‐NMe2, the saturated Ac‐L/DL‐Xaa‐NMe2 shows the constancy of the associative patterns but do not prefer any molecular structure in the solid state. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Diketopiperazines in peptide and combinatorial chemistry
Authors: Fischer Peter M.
Published: January 2003

Diketopiperazines (DKPs), the smallest cyclic peptides, represent an important class of biologically active natural products and their research has been fundamental to many aspects of peptide chemistry. The advent of combinatorial chemistry has revived interest in DKPs for two reasons: firstly, they are simple heterocyclic scaffolds in which diversity can be introduced and stereochemically controlled at up to four positions; secondly, they can be prepared from readily available α‐amino acids using very robust chemistry. Here synthetic methods, conformation, as well as applications of DKPs are summarized and discussed critically. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
A comparison of the performance of lightweight glass containers manufactured by the P&B and B&B processes
Authors: Jaime Sandra Balan Mendoza , Ortiz Sylvio Alves , Dantas Tiago Bassani , Damasceno Cristiano Ferreira
Published: January 2003

The mechanical performance of lightweight glass packages produced by the NNPB (narrow neck press and blow) process was evaluated by comparison with the same glass packages (regular weight) produced by the conventional process (blow and blow). The temper number (annealing process evaluation), thickness distribution behaviour and mechanical performance (impact, vertical load and thermal shock strength) were analysed before and after line simulation, applied in optimized conditions in the laboratory. The performance of lightweight glass packages under transport simulation (truck envelope) in relation to the regular weight bottles was also evaluated. Both bottles presented residual stress values within the specified limits. The lightweight glass bottles had a more homogenous thickness distribution in comparison with the regular weight bottles and a better performance (about 33% improvement) in relation to the impact strength, especially in the heel, even when evaluated after line simulation. As to the vertical load strength, the lightweight glass bottle also indicated a superior performance to the regular weight bottle, both before and after line simulation. Both bottles withstood the temperature difference of 42°C that such packages are supposed to resist according to thermal shock specification. Due to the better thickness distribution of lightweight glass packages, they withstood a maximum temperature difference (progressive thermal shock) of 5–10°C higher than the regular weight bottles. No restrictions of the lightweight glass packages submitted to the transport simulation were found. Copyright © 2002 John Wiley & Sons, Ltd.
The packaging technology and science of ancient transport amphoras
Authors: Twede Diana
Published: January 2003

Commercial transport amphoras are large ceramic vessels that were used from 1500BCto 500ADto ship wine and other products throughout the Mediterranean. The most large‐scale use was to serve the ancient Greek and Roman empires. Although their form is much different from our own packages, the shape and design were clearly the result of the same reasoning that we use to design successful packaging today. They were designed to be economical to produce and ship. The unusual shapes, and especially the pointed base, facilitated handling, storage, transport and use in logistical systems that were very differently shaped from those that we use today. This paper investigates amphoras as a packaging system from a functional approach. It describes their protective physical properties, manufacturing process and industry structure, logistical and marketing advantages, and illustrates the value of such packaging artifacts in documenting the history of trade. Copyright © 2002 John Wiley & Sons, Ltd.
Implementing an applet system without fixing virtual‐machine designs
Authors: Itabashi Kazumasa , Matsubara Katsuya , Moriyama Yutaka , Someya Yuuichi , Kato Kazuhiko , Sekiguchi Tatsuro , Yonezawa Akinori
Published: January 2003

An applet is program code which is downloaded dynamically from a server on the World Wide Web and which can be executed while maintaining security on the client side. The majority of applet systems at present, as represented by the Java Applet, implement the applets using virtual machine code which is independent of computer architecture. This is advantageous in terms of installation and use in different machine environments. Because virtual machine code is associated with execution by an interpreter or conversion to native code, the design of the virtual machine code greatly impacts performance during execution. Normally, however, representation of virtual machine code is fixed for each applet system and cannot be altered. The authors focused on the independence of virtual machine code and implementing an applet execution environment which is independent of the design of virtual machine code by making the Just‐In‐Time (JIT) compiler which converts virtual machine code to native code mobile. In this approach, native code conversion modules which are appropriate for the virtual machine code being used in the applet description are downloaded dynamically. In addition, this applet execution environment provides monitoring functions during applet execution so that a native code applet generated from any virtual machine code can be executed safely. The applet execution monitoring mechanism allows for the programming of system control policies for users, and allows for flexible applet execution control for various levels of monitoring. In this paper, the authors describe an implementation using their newly designed virtual machine code representation in both the SPARC and Intel x86 architecture environments, as well as experiments using this implementation. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(2): 32–42, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10013
A measurement system for the behavior of children with developmental disorder using an omnidirectional camera
Authors: Suga Mikio , Taya Motonori , Minato Kotaro , Yamamura Kanako , Tomohisa Hisao , Komori Masaru
Published: January 2003

In the evaluation of children with developmental disorder, such as autism and learning disabilities (LD), an interview and behavior observation by a doctor or a clinical psychologist, as well as the hearing or behavior checklist completed by the parent or classroom teacher, are employed. Those, however, cannot be quantitative, and it is difficult to analyze in detail the long‐term observation or effectiveness of education or therapy. From such a viewpoint, it is desired to establish a method that can measure the behavior of the child on a more objective and quantitative basis. As a means of behavior measurement, the child may carry a transmitter or a marker, but a child with a developmental disorder often rejects an instrument that directly touches the body, which makes the application difficult. A wide‐angle camera may be employed, but its use is not simple, such as the need for calibration at the site of installation. In this study, a noncontact behavior measurement system is constructed, in which an omnidirectional camera with a hyperbolic mirror is used to determine the spatial position of the child in an objective and quantitative way. Using the constructed system, the behavior of the child with a developmental disorder is examined, and characteristic patterns are observed. It is concluded that the result of such a measurement can be a useful index in the evaluation of the observation of the course of the child with a developmental disorder, as well as in the evaluation of the effectiveness of education or therapy. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(2): 23–31, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10177
A compression method for color images using multilayered neural networks
Authors: Watanabe Eiji , Mori Katsumi
Published: January 2003

Multilayered neural networks can obtain compressed representations for input patterns in the hidden layer, when output patterns are identical with input patterns. However, when color images have complex features, a single neural network model cannot compress them with sufficient accuracy. In this paper, a compression method for color images is proposed based on a group of multilayered neural networks, which can reduce the reconstructed error in stepwise fashion. Finally, the compression and decoding performances of the proposed method are discussed in detail. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(2): 13–22, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10208
Detection of vanishing point sequence with temporal fluctuation
Authors: Minagawa Akihiro , Kobayashi Yukihiko , Tagawa Norio , Tanaka Toshiyuki
Published: January 2003

A method for detecting the vanishing point from sequential images is proposed. In existing methods, a method for detecting the vanishing point from a single image had been discussed. However, since sequential images are frequently used in environment recognition from images, it is important that the temporal fluctuation characteristics caused by camera vibration are considered. In this paper, we introduce such a temporal characteristic, and one vanishing point sequence is stably estimated based on both the temporal characteristic and the information on lines constructed from feature points as observed data. In our approach, the expectation‐maximization (EM) algorithm is used hierarchically, and both maximum a posteriori (MAP) estimation of the vanishing point sequence and line clustering for feature points are simultaneously performed. The saddle point approximation is used for convenience in calculating the expectation with respect to the posterior in the EM algorithm. Experiments in which autoregressive (AR) processing was applied to the temporal characteristics and 400 images were used confirmed that the error was effectively reduced in comparison with the conventional method for images with lower reliability of the observed data. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(2): 1–12, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10259
A development method of time‐triggered object‐oriented software for embedded control systems
Authors: Yokoyama Takanori , Naya Hidemitsu , Narisawa Fumio , Kuragaki Satoru , Nagaura Wataru , Imai Takaaki , Suzuki Shoji
Published: January 2003

This paper describes a time‐triggered object‐oriented model for embedded control systems and a control software development method based on that model. Conventional object‐oriented models had been based on event‐triggered actions. In contrast, we propose a time‐triggered object‐oriented model for real‐time control. This model, which consists of a set of objects for calculating data values required for control, activates these objects cyclically to implement time‐triggered actions. This paper also shows that a distributed control system having location transparency can be implemented efficiently according to this model. In addition, we propose a control software development method based on the proposed time‐triggered object‐oriented model. This development method can extract objects according to simple operations from control block diagrams used to describe control specifications. This paper also introduces an embedded system‐oriented implementation method that does not consume much resource and presents an application example in a distributed control system for automobiles. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(2): 43–54, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1189
Contour extraction of left ventricular cavity from digital subtraction angiograms using a neural edge detector
Authors: Suzuki Kenji , Horiba Isao , Sugie Noboru , Nanki Michio
Published: January 2003

In this paper, a supervised edge detector based on a multilayer neural network, which is called a neural edge detector (NED), is proposed for detecting edges which coincide with edges traced by a human operator (e.g., a medical doctor). The NED is trained by use of the contours traced by a cardiologist. Using the trained NED, the contours coinciding well with the contours traced by a cardiologist are extracted from the left ventricular angiograms even with nonuniform contrast medium.

The proposed contour extraction method consists of (1) detection of fine edges by the NED, (2) extraction of rough contours, and (3) contour tracing based on contour candidates synthesized from the rough contours and the edges detected by the NED. The contour of the left ventricle is automatically extracted by inputting two points manually. Experiments with clinical images show that the proposed method can stably extract the contours coinciding well with the contours traced by a cardiologist. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(2): 55–69, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1190
Adaptive clustering using modular learning architecture
Authors: Suzuki Satoshi , Ueda Naonori
Published: January 2003

We present a clustering method for data that are continuously distributed within each class and where there is no overlap between the classes. With the method the data are clustered by on‐line processing, starting at a point where the number of classes is unknown. The proposed method uses ideas derived from statistical mechanics and applies them to a modular learning architecture: learning progresses by regarding the data as particles and regarding each module as a space in which the particles are distributed. The learning method estimates the energy state that matches the particle distribution. As a result of learning, continuously distributed data are clustered in the same module. At the same time, certain modules appear that contain no data. Consequently, the number of classes is estimated by defining each module containing data as a class. This paper describes the proposed method in detail and shows the results of clustering experiments undertaken using two‐dimensional artificial data and facial images. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(2): 70–80, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1191
Strategy of high‐speed template matching and its optimization by using GA
Authors: Muramatsu Shoji , Otsuka Yuji , Kobayashi Yoshiki , Shimizu Eiji
Published: January 2003

The template matching technique is now applied to various image processing systems, and there is an increasing demand for applications of template matching based on the normalized correlation coefficient, which is robust to variations of illumination. In order to use techniques based on the normalized correlation coefficient in practical application problems, however, high‐speed calculation of the normalized correlation coefficient is required. The purpose of this paper is to increase speed by shrinking the image to be processed. However, stable template matching requires that the features of the image to be processed be retained in the shrunken image. For this purpose, the shrinkage ratio must be determined reasonably considering the properties of the template image as well as the search image. In order to set the shrinkage ratio effectively it is also necessary to preprocess the image so that the features are enhanced. In this study, the combination of the shrinkage ratio and preprocessing, which may depend on the individual image, is optimized by using a genetic algorithm. For evaluation, the proposed method is applied to a real system, and the effectiveness of the method is verified in terms of the practical processing speed and stability. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(2): 81–91, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1192