bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and characterization of organosoluble polyimides with trifluoromethyl‐substituted benzene in the side chain
Authors: Liu J. G. , He M. H. , Li Z. X. , Qian Z. G. , Wang F. S. , Yang S. Y.
Published: August 2002

New aromatic diamines substituted with a trifluoromethyl group in the side chain, 2,4‐diamino‐3′‐trifluoromethylazobenzene, 2,4‐diamino‐1‐[(4′‐trifluoromethylphenoxy) phenyl] aniline, and 3,5‐diamino‐1‐[(4′‐trifluoromethyl phenoxy) phenyl] benzamide were synthesized and characterized and used to prepare polyimides by a one‐step high‐temperature polycondensation method. Experimental results indicated that the prepared polyimides possess good solubility in strong organic solvents such as N‐methyl‐2‐pyrrolidinone, N,N′‐dimethylformamide, and N,N′‐dimethylacetamide. Homogeneous solutions with solid contents as high as 15–20% can be prepared, which are stable for storing longer than 2 weeks at room temperature. The polyimides exhibited glass‐transition temperatures of 249–292 °C and good thermal stability. The PI‐Ic and PI‐IIIc films prepared by casting the fully imidized polymer solutions showed good transparency with cutoff wavelengths at 320–330 nm. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1572–1582, 2002
Polymerization of methyl methacrylate and other polar monomers with alkylaluminum initiators bearing bidentate and tridentate N‐ and O‐donor ligands
Authors: Baugh Lisa Saunders , Sissano Joseph A.
Published: August 2002

Dimethylaluminum complexes bearing bidentate amidate, oxypyridine, and salicylaldimine N,O‐ligands and tridentate N,N′,N″‐pyridyliminoamide ligands were synthesized and spectroscopically characterized. The complexes were investigated in both neutral and borane‐activated cationic forms, along with bidentate N,N′‐ligated aluminum amidinates, as catalysts for the polymerization of methyl methacrylate, ϵ‐caprolactone, and propylene oxide. The neutral complexes generally did not carry out polymerization, but the polymerization/oligomerization of all three monomers was achieved when the various catalysts were activated with B(C6F5)3 or [Ph3C]+[B(C6F5)4]−. The N,O‐ligated cations were much less active for polymerization than the analogous, more stable N,N′‐ligated amidinate cations; both types of cationic complexes catalyzed the ring‐opening cationic polymerization of tetrahydrofuran. B(C6F5)3 and [Ph3C]+[B(C6F5)4]− also independently carried out the oligomerization of propylene oxide. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1633–1651, 2002
Synthesis and characterization of new highly organosoluble poly(etherimide)s derived from 1,1‐bis{4‐[4‐(3,4‐dicarboxyphenoxy)phenyl]‐4‐phenylcyclohexane} dianhydride
Authors: Liaw Der‐Jang , Hsu Chung‐Yu , Hsu Pei‐Nan , Lin Shu‐Ling
Published: August 2002

A new bulky pendent bis(ether anhydride), 1,1‐bis[4‐(4‐dicarboxyphenoxy)phenyl]‐4‐phenylcyclohexane dianhydride, was prepared in three steps, starting from the nitrodisplacement of 1,1‐bis(4‐hydroxyphenyl)‐4‐phenylcyclohexane with 4‐nitrophthalonitrile to form bis(ether dinitrile), followed by alkaline hydrolysis of the bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). A series of new poly(ether imide)s were prepared from the bis(ether anhydride) with various diamines by a conventional two‐stage synthesis including polyaddition and subsequent chemical cyclodehydration. The resulting poly(ether imide)s had inherent viscosities of 0.50–0.73 dL g−1. The gel permeation chromatography measurements revealed that the polymers had number‐average and weight‐average molecular weights of up to 57,000 and 130,000, respectively. All the polymers showed typical amorphous diffraction patterns. All of the poly(ether imide)s showed excellent solubility in comparison with the other polyimides derived from adamantane, norbornane, cyclododecane, and methanohexahydroindane and were readily dissolved in various solvents such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide, pyridine, cyclohexanone, tetrahydrofuran, and even chloroform. These polymers had glass‐transition temperatures of 226–255 °C. Most of the polymers could be dissolved in chloroform in as high as a 30 wt % concentration. Thermogravimetric analysis showed that all polymers were stable up to 450 °C, with 10% weight losses recorded from 458 to 497 °C in nitrogen. These transparent, tough, and flexible polymer films could be obtained by solution casting from DMAc solutions. These polymer films had tensile strengths of 79–103 MPa and tensile moduli of 1.5–2.1 GPa. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2066–2074, 2002
Influence of stereochemistry on the thermal properties of partially cycloaliphatic polyamides
Authors: Vanhaecht Bert , Rimez Bart , Willem Rudolph , Biesemans Monique , Koning Cor E.
Published: August 2002

The effects of the partial substitution of 1,4‐disubstituted cyclohexane monomers for linear aliphatic monomers in polyamides are discussed. More specifically, the relation between the stereochemistry of the cycloaliphatic residues and the thermal properties [melting temperature (Tm) and crystallization temperature (Tcr)] was investigated. For this purpose, two different types of copolyamides were synthesized: in polyamides 12.6, the adipic acid residues were partially replaced by cis/trans‐1,4‐cyclohexanedicarboxylic acid (1,4‐CHDA), whereas in polyamides 4.14, the 1,4‐diaminobutane residues were partially substituted with cis/trans‐1,4‐diaminocyclohexane (1,4‐DACH). For both systems, increasing the degree of substitution of cycloaliphatic residues for linear aliphatic residues resulted in a rise of both Tm and Tcr. This points to the isomorphous crystallization of the linear and cycloaliphatic residues. In contrast to the use of 1,4‐DACH as a comonomer, 1,4‐CHDA residues showed isomerization upon thermal treatment of the polyamides. This isomerization of the cyclohexane residues influenced the thermal properties of the copolyamides. The use of a nonisomerizing cis–trans mixture of 1,4‐DACH exhibited the large influence of the stereochemistry of the cycloaliphatic residues on the Tm of the copolyamides. For both the 1,4‐CHDA‐ and 1,4‐DACH‐based copolyamides, differential scanning calorimetry analysis revealed that recrystallization occurs during melting. This exothermal effect becomes less pronounced with an increasing content of rigid cycloaliphatic residues. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1962–1971, 2002
Synthesis of thermosensitive hydrogels from acryloyloxyethyl trialkyl phosphonium chloride–N‐isopropylacrylamide–N,N′‐methylenebisacrylamide terpolymers and their temperature dependence of water absorption
Authors: Watanabe Tsutomu , Utsunomiya Masayuki , Kurihara Seiji , Nonaka Takamasa
Published: August 2002

Thermosensitive polymer hydrogels were prepared by the copolymerization of three kinds of acryloyloxyethyl trialkyl phosphonium chlorides (AETRs) with alkyl chains of different lengths, with N‐isopropyl acrylamide (NIPAAm) and N,N′‐methylenebisacrylamide (MBAAm). The water content of the AETR–NIPAAm–MBAAm terpolymers obtained at molar ratios of the crosslinking agent greater than 2 decreased with increasing temperature and decreased sharply around 35 °C. However, the water contents of the AETR–NIPAAm–MBAAm (X/100/1) terpolymers obtained at a molar ratio of 1 of the crosslinking agent increased once with increasing temperature and then decreased from 3 to around 40 °C. The water contents of the AETR–NIPAAm–MBAAm (3/100/1 or 2) terpolymers decreased with the increasing length of alkyl chains in phosphonium groups in the terpolymers. The water contents of the AETR–NIPAAm–MBAAm terpolymers increased by the addition of a small amount of urea and then decreased with increasing urea concentration. However, the water contents decreased abruptly with the addition of NaCl. The AETR–NIPAAm–MBAAm terpolymers exhibited high adsorption for sodium dodecylbenzene sulfonate but no adsorption for sodium benzene sulfonate. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1505–1514, 2001
Synthesis and properties of alternating copolyamide‐imides based on 2,6‐bis(4‐aminophenoxy)naphthalene and comparison with its related isomeric polymers
Authors: Yang Chin‐Ping , Yang Chun‐Cheng , Chen Ruei‐Shin
Published: August 2002

A series of novel polyamide‐imides III containing 2,6‐bis(phenoxy)naphthalene units were synthesized by 2,6‐bis(4‐aminophenoxy)naphthalene and various bis(trimellitimide)s in N‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents through direct polycondensation. The polymers were obtained in quantitative yield with inherent viscosities up to 1.53 dL/g. Most of the polymers showed good solubility in NMP, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide and could be solution‐cast into transparent, flexible, and tough films. The films had tensile strengths of 84–111 MPa, elongations at break of 8–33%, and initial moduli of 2.2–2.8 GPa. Wide‐angle X‐ray diffraction revealed that most polymers III were amorphous. The glass‐transition temperatures of some of the polymers could be determined by differential scanning calorimetry traces, recorded at 247–290 °C. The polyamide‐imides exhibited excellent thermal stabilities and had 10% weight loss at temperatures in the range of 501–575 °C under nitrogen atmosphere. They left more than 57% residue even at 800 °C in nitrogen. A comparative study of some corresponding polyamide‐imides is also presented. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2591–2601, 2001
Synthesis and properties of vinyl‐terminated and silicon‐containing polysulfones and polyketones
Authors: Kim Sang Hern , Woo Hee‐Gweon , Kim Joon‐Seop , Lee Hyun‐Woo , Kim Whan‐Gi
Published: August 2002

4‐Fluorophenylsulfonylphenyl‐terminated polysulfone and 4‐fluorobenzoylphenyl ketone were prepared with bisphenol A and an excess of bis‐(4‐fluorophenyl)sulfone or 4,4′‐difluorobenzophenone, respectively, at 160 °C using potassium carbonate in N,N‐dimethylacetamide. The resulting polymers were reacted with 4‐hydroxystyrene to synthesize vinyl‐terminated polysulfones and ketones. The silicon‐containing polysulfones and ketones were prepared from the vinyl‐terminated polymer precursor and various H‐functional silanes or siloxanes. The synthesis of silicon‐containing polymers was achieved by hydrosilation with a rhodium catalyst. It was shown that the hydrosilation reaction proceeds with 55:45 chemoselectivity. The resulting polymers were investigated by 1H NMR spectroscopy, DSC, and thermogravimetric analysis. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2937–2942, 2001
Hyperbranched polyethyleneimine architecture onto poly(allylamine) by simple synthetic approach and the chelating characters
Authors: Kuo Ping‐Lin , Ghosh Swapan K. , Liang Wuu‐Jyh , Hsieh Yun‐Tsung
Published: August 2002

In resemblance to the ethoxylation of alkylamine or polymeric amines to introduce the nonionic hydrophiles by incorporation of ethylene oxide groups to make surfactants, ethyleneimine (EI) groups were introduced into poly(allylamine) by a simple in situ reaction of this polymer with 2‐chloroethylamine hydrochloride. The resultant polymers were allylic and chain‐pendant with hyperbranched polyethyleneimine. The EI number (n) of the polymers was determined by 1H NMR. The percentages of primary, secondary, and tertiary amine present were estimated by potentiometric titration. The chelating abilities of the polymers that were applied growth conditions once (G1, n ≈ 2) and twice (G2, n ≈ 6) were also examined by potentiometric titration and ultraviolet–visible spectoscopy in the presence of metal ions (Cu+2). Continuous‐variation analysis revealed that each repeat unit of G1 and G2 behaves as a multident chelate and forms a stable complex with Cu+2 ions utilizing an average of three EI dents per ion. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3018–3023, 2001
Microemulsion polymerization of acrylamide and styrene: Effect of the structures of reaction media
Authors: Hao Jingcheng
Published: August 2002

Isothermal phase diagrams of the system cetyltrimethylammonium bromide (CTAB)/n‐butanol/n‐octane/water were constructed, and the effect of the oil (n‐octane) contents on the microemulsions was studied at 40 °C. We determined the microemulsion structures of two systems, CTAB/n‐butanol/10% n‐octane/water and sodium dodecyl sulfonate (As)/n‐butanol/20% styrene/water, by conductivity measurements to investigate the polymerization of acrylamide and styrene in the two microemulsion systems. The polymerization kinetics of the water‐soluble monomer acrylamide in CTAB micelles and the different CTAB/n‐butanol/10% n‐octane/water microemulsion media [water‐in‐oil (W/O), bicontinuous (BC), and oil‐in‐water (O/W)] were studied with water‐soluble sodium bisulfite as the initiator. The maximum polymerization rate in CTAB micelles was found at the second critical micelle concentration. A mechanism of polyacrylamide formation and growth was proposed. A connection between the structures of the microemulsions and the polymerization rates was observed; the maximum polymerization rate occurred at two transition points, from W/O to BC and from BC to O/W, and the polyacrylamide molecular weights, which depended on the structures of the microemulsions, were also found. A square‐root dependence of the polymerization rates on the initiator concentrations was obtained in CTAB micelles and O/W microemulsion media. The polymerization of the oil‐soluble monomer styrene in different As/n‐butanol/20% styrene/water microemulsion media (W/O, BC, and O/W) was also investigated with different initiators: water‐soluble potassium persulfate and oil‐soluble azobisisobutyronitrile. A similar connection between the structures of the microemulsions and the conversions of styrene in CTAB/n‐butanol/10% n‐octane/water for the polymerization of acrylamide was observed again. The structures of the microemulsions had an important role in the molecular weights and sizes of polystyrene. The polystyrene particles were 10–20 nm in diameter in BC microemulsion media and 30–60 nm in diameter in O/W microemulsion media according to transmission electron microscopy. We determined the solubilization site of styrene in O/W microemulsion drops by 1H NMR spectra to analyze the results of the microemulsion polymerization of styrene. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3320–3334, 2001
Relationship of deformation behavior to thermal transitions of ethylene/styrene and ethylene/octene copolymers
Authors: Chang A. , Cheung Y. W. , Hiltner A. , Baer E.
Published: August 2002

The stress‐strain response of low‐crystallinity ethylene‐octene (EO) and ethylene‐styrene (ES) copolymers with 7–20 mol % comonomer was compared over a temperature range that spanned the glass‐transition and crystal melting regions. Above the onset temperature of the glass transition, the copolymers exhibited elastomeric behavior with low initial modulus, uniform deformation to high strains, and high recovery after the stress was released. In the glass‐transition range, an initial low‐stress elastomeric response was followed by a distinct “bump” in the stress‐strain curve. On the basis of the temperature and rate dependence of the stress‐strain curve, local strain‐rate measurements, local temperature changes, and recovery characteristics, the “bump” was identified as high strain yielding. Hence, the stress‐strain curve sequentially exhibited the features of elastomeric and plastic deformation. Following high strain yielding, strain hardening dramatically increased the fracture strength. This behavior was defined as elastomeric‐plastic. Elastomeric‐plastic behavior in the broad glass‐transition range constituted a gradual transition from elastomeric behavior at higher temperatures to low‐temperature plastic behavior with high modulus and macroscopic necking. Because of the lower glass‐transition temperature of EO, −40 °C as compared with −10 °C for ES, the onset of elastomeric‐plastic behavior occurred at a significantly lower temperature. The concept of a network of flexible chains with fringed micellar crystals serving as the multifunctional junctions that provides the structural basis for elastomeric behavior of low‐crystallinity ethylene copolymers was extended to elastomeric‐plastic behavior by considering a network with a fraction of rigid, glassy chains. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 142–152, 2002
Effect of coagulation conditions on the microfibrillar network of a rigid polymer
Authors: Tsabba Yizhak , Rein Dmitry M. , Cohen Yachin
Published: August 2002

An important element in the microstructure of high performance fibers and films fabricated from rigid polymers is an interconnected network of oriented microfibrils, the lateral size of which is about 10 nm. This study is an attempt to elucidate the mechanism by which the microfibrils are formed so that larger lateral dimensions can be achieved by suitable processing. Because this morphology emerges in the coagulation stage of the spinning process, we compared the microfibrillar network formed by drastically different coagulation conditions. Ribbons, spun from solution of poly(p‐phenylene benzobisthiazole) in polyphosphoric acid through a slit die, were coagulated either in the ordinary rapid process with water (timescale of seconds) or in a slow process with phosphoric acid (timescale of hours). The coagulated microfibrillar network was dried with supercritical CO2 for X‐ray scattering measurements and impregnated with epoxy resin for sectioning and imaging by TEM. Slow coagulation yields better‐aligned microfibrils of enhanced chain packing, but the lateral size of the microfibrils formed in both cases is similar, about 10 nm. Heat treatment increases the width of water‐coagulated microfibrils but not the acid‐coagulated ones. The observations do not support spinodal decomposition as the mechanism of microfibril formation during coagulation, as was previously suggested. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1087–1094, 2002
Molecular composites made of ionic poly(p‐phenylene terephthalamide) and poly(4‐vinylpyridine): Relaxation behavior
Authors: Chen W. C. , Sauer J. A. , Hara M.
Published: August 2002

Molecular composites were prepared from several types of ionically modified, poly(p‐phenylene terephthalamide) (PPTA) dispersed in a poly(4‐vinylpyridine) matrix. Optical clarity tests indicated that the component polymers of the composite were miscible, at least at low concentrations of the rodlike reinforcement. In composites containing ionic PPTA, where ionic sulfonate groups were attached as side groups either to PPTA chains or to PPTA anion chains, the glass‐transition temperature (Tg) was increased by l0 °C or more, at 5 wt % reinforcement. At concentrations of 10–15 wt % of the ionic polymer, Tg values leveled off or decreased slightly. This suggested that some aggregation of the rigid‐rod molecules occurred. In composites containing ionic PPTA, where the ionic sulfonate groups were directly attached to the phenylene rings of PPTA chains, not only was Tg shifted significantly to higher temperatures, but the rubbery plateau modulus retained high values up to temperatures of 250 °C or above. Observed effects were considered to be the result of strong ionic interactions between the ionic reinforcement polymer and the polar matrix polymer. The possible effects of the counterion on Tg and the storage modulus are discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1110–1117, 2002
ESR studies in γ‐irradiated and PS‐radiation‐grafted poly(vinylidene fluoride)
Authors: Aymes‐Chodur C. , Esnouf S. , Le Moël A.
Published: August 2002

The fluoropolymer poly(vinylidene fluoride) was irradiated with γ rays to induce a polystyrene (PS) radiation grafting via an indirect method. Electron spin resonance and Fourier transform infrared studies were performed to identify the species that initiated the PS grafting. Specific experiments were performed to prove separately the importance of each kind of radical. A localization of the radicals in this irradiated polymer is proposed, and a kinetic model of the grafting is given. © 2001 John Wiley & Sons, Inc. J Polym Sci B Part B: Polym Phys 39: 1437–1448, 2001
Polytetrahydrofuran amphiphilic networks. IV. Swelling behavior of poly(acrylic acid)‐l‐polytetrahydrofuran and poly(methacrylic acid)‐l‐polytetrahydrofuran networks
Authors: Guan Ying , Jiang Weiwen , Zhang Wenchuan , Wan Guoxiang , Peng Yuxing
Published: August 2002

Poly(acrylic acid)‐l‐polytetrahydrofuran (PAA‐l‐PTHF) and poly(methacrylic acid)‐l‐polytetrahydrofuran (PMAA‐l‐PTHF) networks were synthesized by the free‐radical copolymerization of hydrophobic polytetrahydrofuran diacrylates with hydrophilic acrylic acid and methacrylic acid. Their swelling behavior was studied. Both PAA‐l‐PTHF and PMAA‐l‐PTHF networks had four solubility parameters, which indicated that they exhibited not only the properties of both hydrophobic and hydrophilic segments but also the combined properties of these two segments. The swell of these two series of networks was composition‐dependent in organic solvents and water. The relationship between the equilibrium swelling ratio (SRe) in nonpolar solvents and the composition of the networks [the weight fraction of the PTHF segment (PTHF%)] may be expressed with a linear equation: SRe = A × PTHF% + B. A and B are parameters that relate to the interaction of hydrophilic and hydrophobic segments with nonpolar solvents and to the properties of the networks, respectively. Because of the presence of a COOH group, these two network series were pH‐sensitive when the content of hydrophilic segments was higher. The pH sensitivity of networks could be controlled not only by the composition of the networks but also by the hydrophobic degree of the hydrophilic segments. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1784–1790, 2001
Characterization of polyolefin melts using the polymer reference interaction site model integral equation theory with a single‐site united atom model
Authors: Freischmidt Helen M. , Shanks Robert A. , Moad Graeme , Uhlherr Alfred
Published: August 2002

A general approach, based on the polymer reference interaction site model (PRISM) integral equation theory, suitable for characterizing arbitrarily complex polyolefin melts is described. We tested the method by calculating the melt structures of linear polyethylene (PE) and isotactic polypropylene (iPP) and the spinodal decomposition temperatures for PE/iPP blends. The computational expense of the PRISM calculation was reduced with a single‐site united atom model in which the polyolefin CH, CH2, and CH3 groups were approximated as chemically equivalent sites with spherically symmetric energetic interactions. The site–site interactions were defined by a potential function comprising a hard core with an attractive Lennard–Jones term. These energetic parameters were optimized with a central composite design strategy that enabled a simultaneous fit of experimental melt density and structure factor data. Values were obtained for PE and iPP individually and for common universal parameters that could potentially be used for all polyolefins. The rotational isomeric state–metropolis Monte Carlo (RMMC) technique was used to generate sets of conformers at specified temperatures covering the melt‐temperature range of the polymers. The characteristic ratio was used to assess the quality of the conformers and the RMMC method. Values of 9.68 for PE and 9.27 for iPP were obtained. The single‐chain structure factors calculated by the RMMC method were used to calculate the total structure factor for each melt. These were validated against published X‐ray diffraction results. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1803–1814, 2001
Phase behavior of ternary poly‐(2‐vinylpyridine)/poly‐(N‐vinyl‐2‐pyrrolidone)/bis‐(4‐hydroxyphenyl)methane blends
Authors: Li Xue‐Dong , Goh S. H.
Published: August 2002

The phase behavior of ternary poly‐(2‐vinylpyridine) (P2VPy)/poly‐(N‐vinyl‐2‐pyrrolidone) (PVP)/bis‐(4‐hydroxyphenyl)methane (BHPM) blends was studied. Fourier transform infrared spectroscopic examinations demonstrated that BHPM interacts with P2VPy and PVP through hydrogen‐bonding interactions. The addition of a sufficiently large amount of BHPM transformed an opaque blend with two glass‐transition temperatures (Tg's) to a transparent single‐Tg blend. Scanning electron microscopic studies showed that the transparent single‐Tg blend is micro‐phase‐separated at a scale of about 30 nm. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1815–1823, 2001
Oxygen‐barrier properties of polyethylene terephthalate modified with a small amount of aromatic comonomer
Authors: Polyakova A. , Connor D. M. , Collard D. M. , Schiraldi D. A. , Hiltner A. , Baer E.
Published: August 2002

The oxygen‐barrier properties of amorphous copolyesters based on ethylene terephthalate with 10%, or less, of an acid comonomer were examined. Comonomer units were isophthalate, phthalate, 1,5‐naphthalate, 1,8‐naphthalate, 2,6‐naphthalate, 1,8‐anthracenate, 2,6‐anthracenate, and 2,7‐pyrenate. Even 2.5 mol % comonomer significantly affected the permeability. Linear comonomers decreased the permeability. In contrast, small amounts of a kinked comonomer increased the permeability. However, increasing the amount of kinked comonomer further (gradually) decreased permeability P below that of polyethylene terephthalate. Generally, comonomer affected solubility S less than diffusivity D; therefore, changes in P reflected primarily changes in D. The solubility and diffusivity depended on copolymer composition in accordance with static and dynamic free‐volume concepts of gas permeability in glassy polymers. The solubility correlated with the amount of free volume, as determined by the glass‐transition temperature. This study also explored the relationship of dynamic free volume, which determines D, to thermally accessible segmental motions of the polymer chain. The effect of comonomer on D correlated with the intensity of the gauche component of the subambient γ relaxation. Changes in the fraction of gauche‐glycol conformations resulting from copolymerization were confirmed by Fourier transform infrared spectroscopy. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1900–1910, 2001
Small‐angle x‐ray scattering study of thermoreversible poly(vinyl chloride) gels
Authors: Seki Motohiro , Yamamoto Satoru , Aoki Yuji , Takagi Katsuhiro , Izumi Yoshinobu , Nojima Shuichi
Published: August 2002

Poly(vinyl chloride) (PVC)/bis(2‐ethylhexyl)phthalate (DOP) gels were prepared at room temperature from tetrahydrofuran solutions of PVC and DOP. PVC/DOP gels of different molecular weights at various PVC concentrations (c) were investigated with small‐angle X‐ray scattering (SAXS). The mean distance between two neighboring inhomogeneities (D) and two characteristic lengths, the intrainhomogeneity distance (d1) and interinhomogeneity distance (d2), were evaluated from Bragg's law and the distance distribution function, respectively. Both D and d2 can be expressed by a power‐law relation (e.g., D and d2 ∝ c−0.5). After a period of rapid cooling to 25 °C from the sol state, the structural evolution was examined with time‐resolved SAXS measurements. An Avrami analysis with the SAXS invariant data revealed that the growth kinetics of PVC/DOP gels was one‐dimensional growth from predetermined nuclei, regardless of c. These results suggest that the PVC/DOP gels are constructed from a fibrillar structure that forms gel structures at high concentrations or low temperatures. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2340–2350, 2001
Crystallization kinetics for low‐ether‐content polyether–polyester block copolymers with amide linkages
Authors: Ho Rong‐Ming , Hseih Ping‐Yen , Yang Ching‐Cheng , Lin Jiang‐Jen
Published: August 2002

A series of low‐ether‐content polyether–polyester block copolymers with amide linkages were synthesized. Their crystallization kinetics and mechanisms were investigated. The crystallization kinetics were analyzed via Avrami treatment; an average value of 1.8 for the Avrami index was thus obtained. Athermal nucleation was evidenced by observations of a linear boundary between impinged spherulites under polarized light microscopy and transmission electron microscopy. The development of spherulitic morphology with a hedgehog texture was attributed to the mechanism of lamellar branching. On the basis of the morphological observations and Avrami analysis, a crystallization mechanism through a heterogeneous nucleation process with homogeneous lamellar branching was proposed. No regime transition was found for polyether–polyesters in the examined temperature ranges, and the crystallization was identified as regime I kinetics on the basis of a Lauritzen Z test. The copolymerization of poly(ether amide)s with polyesters led to a significant suppression of the crystallization rate of polyester crystals. The suppression was explained as the result of a dilution effect in nucleation combined with an increasing nucleation barrier. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2469–2480, 2001
Some morphometric measurements on ploughing blocks in the McGregor Mountains, Canadian Rockies
Authors: Hall K. , Boelhouwers J. , Driscoll K.
Published: August 2002

Morphology and site characteristics are described for ploughing blocks in a sub‐alpine zone of the Canadian Rockies. The ploughing block features (blocks, troughs, levees, etc.) are generally larger than those described for other parts of the world. Good correlations were found between block size and both depression size and mound height. A number of ancillary observations and measurements suggest active block movement in the study area. Copyright © 2001 John Wiley & Sons, Ltd.

La morphologie et les caractéristiques des sites où se trouvent des blocs labourant sont décrites dans une zone sub‐alpine des Rocheuses canadiennes. Les caractéristiques de ces blocs labourant (taille des blocs, importance des sillons, levées, etc.) sont généralement plus grandes que celles décrites dans d'autres régions du monde. De bonnes corrélations sont trouvées entre la taille des blocs et, à la fois, la dimension des sillons et la hauteur des levées. De nombreuses observations accessoires et des mesures suggèrent que des mouvements de blocs se produisent actuellement dans le secteur étudié. Copyright © 2001 John Wiley & Sons, Ltd.
Location of permafrost in marginal regions: Corral del Veleta, Sierra Nevada, Spain
Authors: Gómez Antonio , Palacios David , Ramos Miguel , Tanarro Luis M. , Schulte Lothar , Salvador Ferran
Published: August 2002

This article discusses the methodology and techniques used in observations of permafrost, which is confined to a small enclave in south‐east Spain (Corral del Veleta, Sierra Nevada, 3398 m altitude, 37°03′ N, and 3°22′ W). Several geophysical, geothermal and geomorphologic prospecting techniques were used to locate the permafrost at Corral del Veleta, an area highly sensitive to slight climatic variations, and to study its evolution under marginal conditions. The results from the application of this methodology confirm the location of Europe's southernmost permafrost remnant. Copyright © 2001 John Wiley & Sons, Ltd.

Le présent article discute la méthodologie et les techniques utilisées pour observer le pergélisol qui se trouve dans un petit territoire du sud‐est de I'Espagne (Corral del Veleta, Sierra Nevada, 3.398 m d'altitude, 37° 03′ N, 3°22′ W). Différentes techniques de prospection géophysiques, géothermiques et géomorphologiques ont été utilisées pour localiser le pergélisol dans le site de Corral del Veleta, un endroit hautement sensible aux variations climatiques et favorables à l'étude de son évolution sous des conditions marginales. Les résultats de l'application de cette méthodologie confirment qu'il s'agit du lambeau le plus méridional de pergélisol européen. Copyright © 2001 John Wiley & Sons, Ltd.
Bronchial trifurcation in a congenital pulmonary venolobar syndrome*
Authors: de Lagausie Pascal , Van Den Abbeele T. , Elmaleh M. , Ferkadji L. , Maintenant J. , Aigrain Y.
Published: August 2002

Congenital malformations of the tracheobronchal tree and the related arterial blood supply are a complex group of lesions in which there are abnormalities of the venous drainage and lung parenchyma. These malformations are examples of congenital pulmonary venolobar syndrome (CPVS). Tracheal trifurcation is an extremely rare anomaly associated with CPVS. We report on an unusual case of lower right extralobar sequestration connected to the trachea, plus a type I posterior laryngeal cleft, an aberrant systemic artery, and an anomalous route of the phrenic nerve. This paper discusses the place of this unusual abnormality in the spectrum of congenital bronchopulmonary vascular malformations. Pediatr Pulmonol. 2001; 31:303–305. © 2001 Wiley‐Liss, Inc.
Cystic fibrosis and down's syndrome: Not always a poor prognosis
Authors: Saglani Sejal , Bush Andrew
Published: August 2002

A child developed a bronchiolitis‐like illness and was found to have mosaic Down's syndrome (diagnosed on karyotype) and also cystic fibrosis, diagnosed on the basis of a high sweat osmolality (247 mosmoles/kg sweat; normal, 62–137) and a homozygous delta F508 genotype. Despite two potentially life‐threatening conditions, the child is doing well at the age of 7 years, despite pancreatic insufficiency. Pediatr Pulmonol. 2001; 31:321–322. © 2001 Wiley‐Liss, Inc.
Cell‐specific expression of manganese superoxide dismutase protein in the lungs of patients with respiratory distress syndrome, chronic lung disease, or persistent pulmonary hypertension*
Authors: Asikainen Tiina M. , Heikkilä Päivi , Kaarteenaho‐Wiik Riitta , Kinnula Vuokko L. , Raivio Kari O.
Published: August 2002

The developmental profile of manganese superoxide dismutase (MnSOD) and its regulation in hyperoxia vary between species. We hypothesized that MnSOD increases in human lung in response to oxygen treatment, although this response could be restricted to certain cell types and depend on gestational age. Therefore, the cell‐specific expression of pulmonary immunoreactive MnSOD protein was investigated during development, and in patients with respiratory distress syndrome (RDS), chronic lung disease (CLD), or persistent pulmonary hypertension (PPHN).

Throughout ontogenesis, all cell types expressed MnSOD, but the most intense positivity was found in bronchiolar epithelium and (pre‐) type‐II pneumocytes. MnSOD protein did not increase during development. The MnSOD staining pattern in arterial endothelium was more intense in RDS patients than in age‐matched controls, but this may be related to induction of MnSOD by increased blood flow rather than by oxygen. MnSOD expression in other cell types of RDS, CLD, or PPHN patients did not differ from that in age‐matched controls.

We conclude that, in terms of mitochondrial enzymatic superoxide scavenging capacity, preterm infants are not more vulnerable than term infants to oxygen‐induced lung injury at physiological oxygen concentrations. However, the inability to induce MnSOD in response to oxygen treatment may result in a poor outcome. Pediatr Pulmonol. 2001; 32:193–200. © 2001 Wiley‐Liss, Inc.
Necrotizing tracheobronchitis in patent ductus arteriosus‐dependent cyanotic congenital heart disease
Authors: Nakata Yuji , Morikawa Yoshiyuki , Miura Masaru , Kawasaki Kazuki , Toyoma Hiroshi , Kameyama Kaori
Published: August 2002

We report 2 patients with necrotizing tracheobronchitis (NTB) associated with patent ductus arteriosus‐dependent cyanotic congenital heart disease. The pathologic findings suggest that hypotension and decreased tracheo‐bronchial perfusion were the major contributing factors in the development of NTB. Necrotizing tracheobronchitis developed in infants with pulmonary atresia and Ebstein's anomaly with pulmonary stenosis. Both infants required prostaglandin E1 infusion from early infancy, and presented with sudden onset of dyspnea and hypercapnea. In one infant, NTB developed prior to mechanical ventilation. In the other infant, NTB developed after 4 days of mechanical ventilation. Care of both infants involved minimal pressures and FiO2, adequate humidification, and optimal temperature of inspired gases; these factors probably did not play a role in the development or worsening of NTB. Both infants had hypotension and hypoxemia. These factors could have contributed to the development of NTB because of decreased perfusion pressure and tissue hypoxia. As the area of necrosis and its severity correlated with the area of blood supply served by the specific feeding arteries, we speculate that tissue hypoperfusion was the major cause of NTB. Pediatr Pulmonol. 2001; 32:480–483. © 2001 Wiley‐Liss, Inc.
Ventral prostate predominant l, a novel mouse gene expressed exclusively in the prostate*
Authors: Wubah Judith A. , Fischer Carolyn M. , Rolfzen Laura N. , Khalili May , Kang Jason , Green Jeffrey E. , Bieberich Charles J.
Published: August 2002

BACKGROUND

Despite the region‐specific nature of human prostate disease, there is a paucity of information regarding the molecular basis of prostate regionalization and patterning. To elucidate genetic mechanisms that underlie prostate growth and development, we investigated differential gene expression in mouse prostate lobes.

METHODS

mRNA differential display analysis was used to identify differentially expressed genes during development of ventral, anterior, and dorsolateral prostate lobes. Differential gene expression was confirmed by Northern blot analysis and RT‐PCR.

RESULTS

A novel gene, Ventral prostate predominant1 (Vpp1) was identified. Vpp1 mRNA was evident in all lobes but accumulated predominantly in the ventral prostate, and was detected on postnatal day 7 through adulthood exclusively in the prostate gland. The steady‐state level of Vpp1 mRNA decreased markedly in response to castration, suggesting androgen regulation of Vpp1 expression. Analysis of TRAMP tumors demonstrated a dramatic decrease in the level of Vpp1 mRNA.

CONCLUSIONS

The spatial distribution and early postnatal onset of Vpp1 expression is consistent with a role for this gene in prostate regionalization. The absolute prostate specificity of Vpp1 expression may allow this gene to serve as a paradigm to study the molecular basis of gene expression that is restricted exclusively to the prostate gland. Prostate 51:21–29, 2002. © 2002 Wiley‐Liss, Inc.
CAG polymorphic repeat lengths in androgen receptor gene among Japanese prostate cancer patients: Potential predictor of prognosis after endocrine therapy
Authors: Suzuki Hiroyoshi , Akakura Koichiro , Komiya Akira , Ueda Takeshi , Imamoto Takashi , Furuya Yuzo , Ichikawa Tomohiko , Watanabe Masatoshi , Shiraishi Taizo , Ito Haruo
Published: August 2002

BACKGROUND

Several investigators have examined the clinical significance of the length of the CAG repeat at the N‐terminal region of the androgen receptor in the pathogenesis of prostate cancer. Because the clinical significance of CAG repeat length during the course of prostate cancer in Japanese patients is unknown, the present study analyzed CAG repeat length in relation to several potential clinical factors.

MATERIALS AND METHODS

A total of 88 Japanese patients with prostate cancer and a control group of 53 patients with benign prostatic disease were enrolled in this study. The length of the CAG repeat was determined by PCR sequencing and analyzed in relation to several clinical factors.

RESULTS

The length of the CAG repeat did not significantly differ between prostate cancer and benign prostatic disease. Although not statistically different with regard to clinical stage and serum PSA level, the CAG repeat length was associated with histological grade and age at diagnosis. In addition, the CAG repeat length in CR and in non CR patients significantly differed at 22.1 ± 2.4 and 24.4 ± 3.0, respectively (P = 0.0264), suggesting that the CAG repeat length can act as a molecular marker with which to predict response to endocrine therapy in stage D prostate cancer patients.

CONCLUSIONS

A shorter CAG repeat length appears to predict a response to endocrine therapy, showing a positive prognostic value and indicating good prognosis in the metastatic stage of prostate cancer patients. Prostate 51: 219–224, 2002. © 2002 Wiley‐Liss, Inc.
Three‐dimensional model of the cyclin‐dependent kinase 1 (CDK1): Ab initio active site parameters for molecular dynamics studies of CDKS
Authors: Cavalli Andrea , Dezi Cristina , Folkers Gerd , Scapozza Leonardo , Recanatini Maurizio
Published: August 2002

Cyclin‐dependent kinase 1 (CDK1) is an interesting target for potential anticancer drugs, and its three‐dimensional (3D) structure is presently unknown. The purpose of this work was to build a 3D model of CDK1, which could be used in drug design studies. The protein 3D structure was homology modeled, based on the known crystal structure of CDK2, and new nonbonded parameters for the Mg2+ coordination complex were developed by means of ab initio quantum chemical calculations. These parameters were both obtained and validated using the CDK2 structure as reference, and then they were used for the refinement of the CDK1 model. The resulting CDK1 structure was satisfactory and stable at room temperature, as shown by the molecular dynamics simulations carried out over a 1‐ns time interval on the entire protein. A number of representative kinases in the active and inactive form, including the inactive CDK1 modeled in this work, were compared. The results illustrate the conformational variability of the activation loop of the inactive form of the kinases and suggest a way for selectively targeting the single CDKs. Proteins 2001;45:478–485. © 2001 Wiley‐Liss, Inc.
Stability and conformational dynamics of metallothioneins from the antarctic fish Notothenia coriiceps and mouse
Authors: Capasso Clemente , Abugo Omoefe , Tanfani Fabio , Scire Andrea , Carginale Vincenzo , Scudiero Rosaria , Parisi Elio , D'Auria Sabato
Published: August 2002

The structural properties and the conformational dynamics of antarctic fish Notothenia coriiceps and mouse metallothioneins were studied by Fourier‐transform infrared and fluorescence spectroscopy. Infrared data revealed that the secondary structure of the two metallothioneins is similar to that of other metallothioneins, most of which lack periodical secondary structure elements such as α‐helices and β‐sheets. However, the infrared spectra of the N. coriiceps metallothionein indicated the presence of a band, which for its typical position in the spectrum and for its sensitivity to temperature was assigned to α‐helices whose content resulted in 5% of the total secondary structure of the protein. The short α‐helix found in N. coriiceps metallothionein showed an onset of denaturation at 30°C and a Tm at 48°C. The data suggest that in N. coriiceps metallothionein a particular cysteine is involved in the α‐helix and in the metal‐thiolate complex. Moreover, infrared spectra revealed that both proteins investigated possess a structure largely accessible to the solvent. The time‐resolved fluorescence data show that N. coriiceps metallothionein possesses a more flexible structure than mouse metallothionein. The spectroscopic data are discussed in terms of the biological function of the metallothioneins. Proteins 2002;46:259–267. © 2002 Wiley‐Liss, Inc.
Dermal pharmacokinetics of the insecticide furathiocarb in rats
Authors: Liu Kwang‐Hyeon , Sung Ha‐Jung , Lee Hae‐Keun , Song Byung‐Hun , Ihm Yang‐Bin , Kim Kyun , Lee Hye‐Suk , Kim Jeong‐Han
Published: August 2002

The pharmacokinetics of furathiocarb were studied in vivo in male Sprague–Dawley rats following dermal treatment. HPLC and post‐column derivatization were used for the analysis of furathiocarb and its metabolites (carbofuran, 3‐hydroxycarbofuran and 3‐ketocarbofuran). Carbofuran and 3‐hydroxycarbofuran were detected in plasma and urine rather than furathiocarb. 3‐Ketocarbofuran, another potential metabolite, was not observed in any sample. The concentration of carbofuran was higher than that of 3‐hydroxycarbofuran in plasma, but the reverse was the case in urine. The corresponding area under the plasma concentration–time curve, Tmax, and Cmax values of carbofuran and 3‐hydroxycarbofuran for 1500 mg kg−1 doses were 2.4–8.0 mg equiv h ml−1, 12 h and 0.1–0.4 mg equiv ml−1, respectively. T1/2 was calculated only for 3‐hydroxycarbofuran (28 h). Two metabolites were excreted in a dose‐dependent manner without saturation.

© 2001 Society of Chemical Industry
Synthesis of Tetrapeptide p‐nitrophenylanilides containing dehydroalanine and dehydrophenylalanine and their influence on cathepsin C activity
Authors: Makowski Maciej , Pawełczak Małgorzata , Latajka Rafał , Nowak Kornel , Kafarski Paweł
Published: August 2002

Three dehydrotetrapeptides of rationally varying structure were prepared and tested as affectors of cathepsin C. These compounds appeared to be substrates of the enzyme, being equipotent with their classical counterparts. Thus, replacement of amino acid in a short peptide by corresponding dehydroamino acid does not prevent cathepsin C in recognizing dehydropeptide as its substrate. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
The anxiolytic effect of Sho‐ju‐sen, a Japanese herbal medicine, assessed by an elevated ­plus‐maze test in mice
Authors: Kuribara Hisashi , Iwata Hisato , Tomioka Hideo , Takahashi Reiko , Goto Kazumi , Murohashi Naomi , Koya Sakuji
Published: August 2002

Sho‐ju‐sen (SK), a Japanese herbal medicine with a nourishing tonic action, is composed of a water extract of Kumazasa leaves (Sasa kurinensis Makino et Sibata) (SS), and ethanol extracts of Japanese red pine needles (Pinus densiflora Sieb. et Zucc) (PN) and Ginseng roots (Panax ginseng C. A. Meyer) (PX) in the ratio 8:1:1. In this study, an elevated plus‐maze test in mice was carried out to assess whether SK had an anxiolytic effect. No significant change was observed in either the plus‐maze or activity test following a single administration of SK (10 and 20 mL/kg p.o.). However, mice allowed a free intake of SK (10% solution) for 5 days and longer showed a significant prolongation of the time spent in the open arms (an anxiolytic effect), as long as that caused by the benzodiazepine anxiolytic diazepam (1 mg/kg p.o.). SK (1%, 3% and 30% solutions for 7 days) tended to develop the anxiolytic effect. Of the constituents of SK, SS (8% solution), but not PN (1% solution) or PX (1% solution), resulted in the anxiolytic effect. Except for a slight acceleration in the motor activity by PN (1% solution), no significant change in the motor activity was produced by any treatment with SK, SS or PX. The combined treatment of SK (10% solution) or SS (8% solution) with 1 mg/kg diazepam enhanced the anxiolytic effect. Flumazenil (0.1 mg/kg s.c.), a benzodiazepine receptor antagonist, alone did not change the time spent in the open arms. However, it completely reversed the anxiolytic effect of SK, SS and diazepam. The present results suggest that: (1) long‐term treatment with SK develops an anxiolytic effect, (2) SS is the main constituent for the anxiolytic effect of SK, and (3) benzodiazepine receptors are involved in the anxiolytic effect of SK and SS. Copyright © 2001 John Wiley & Sons, Ltd.