bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and properties of thermoplastic poly(glycerol sebacate) elastomers originating from prepolymers with different molecular weights
Authors: Liu Quanyong , Tian Ming , Shi Rui , Zhang Liqun , Chen Dafu , Tian Wei 
Published: January 2007

AbstractThermoplastic poly(glycerol sebacate) (TMPGS) elastomers originating from three prepolymers with different molecular weights were prepared first, and then the structure and properties were studied. Specifically, by swelling tests, gel permeation chromatography, X‐ray diffraction, and differential scanning calorimetry, the crosslinking densities, sol contents and compositions, crystallization, and thermal performances of three TMPGSs were examined. Finally, the degradability in a 37°C phosphate‐buffered saline solution (pH = 7.4) was also illuminated. The three TMPGSs had similar chemical structures, but the different molecular weights of the prepolymers influenced their final compositions and properties to a great extent. Furthermore, both hydrogen bonding and plasticization action in the elastomers played important roles in balancing the overall properties of the TMPGS elastomers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1131–1137, 2007
Effect of mesogenic crosslinking units on the mesomorphic phases of cholesteric liquid crystalline polymers
Authors: Meng Fan‐Bao , Zhang Bao‐Yan , Zhou Ai‐Juan , Li Xi‐Zhi 
Published: January 2007

AbstractA series of cyclosiloxane‐based cholesteric liquid crystalline polymers were synthesized from cholest‐5‐en‐3‐ol (3β)‐4‐(2‐propenyloxy)benzoate and a nematic crosslinking monomer biphenyl‐4,4′‐diol bis[4‐(2‐propenyloxy)‐benzoate], containing mesogenic crosslinking contents among 0–7.8 wt %. Swelling experiments of the elastomers were employed to determine the effective crosslink density (Mc). With increase of mesogenic crosslinking component in the polymers, the isotropic temperature decreases, but both the temperature of glass transition and melting point change irregularly. All the polymers have high thermal stability and percentage weight loss occurred at 460°C decreases with increase of crosslinking units. The intensity of X‐ray diffraction peak at 2θ ≈ 17° decreases with increase of mesogenic crosslinking units, suggesting that the order between two neighbor liquid crystalline molecules disturbed by the mesogenic crosslinking agents. The maximum reflection bands shift slightly to long wavelength and become broad, indicating that the helical structure is partially disrupted because of both the constraint of chemical crosslinking agents and the different mesogenic units. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1161–1168, 2007
Acetylation reaction of polytetramethylene glycol with acetic anhydride in pyridine
Authors: Ge Zhen , Zhang Xingyuan , Dai Jiabing , Li Weihu , Chao Jing , Feng Linlin 
Published: January 2007

AbstractThe acetylation reaction of polytetramethylene glycol (PTMG) with acetic anhydride in pyridine was studied. The extent of acetylation was measured by 1H‐NMR, and the acetylation product was characterized with FTIR, 1H‐NMR, and 13C‐NMR. The effects of the experimental conditions, i.e., reaction time and temperature, acetylation reagent concentration (anhydride and hydroxyl molar ratio), were investigated. The increase in reaction temperature and reaction time favored the acetylation yields. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1138–1142, 2007
Preparation of new poly(amide–imide)s with chiral architectures via direct polyamidation reaction
Authors: Mallakpour Shadpour , Kolahdoozan Majid 
Published: January 2007

AbstractN‐trimellitylimido‐L‐methionine (3) was prepared by reaction of trimellitic anhydride (1) with ‐L‐methionine (2) in acetic acid solution at refluxing temperature. This diacid was reacted with thionyl chloride, and N‐trimellitylimido‐L‐methionine diacid chloride (4) was obtained in quantitative yield. The resulting diacid chloride was reacted with p‐aminobenzoic acid in dry acetone and bis(p‐aminobenzoic acid)‐N‐trimellitylimido‐L‐methionine (5) was obtained as a novel optically active amide–imide diacid monomer in high yield. The direct polycondensation of amide–imide diacid monomer 5 with several aromatic diamines was carried out with tosyl chloride (TsCl)/pyridine (Py)/dimetheylformamide (DMF) system. The resulting thermally stable poly(amide–imide)s (PAIs) were obtained in good yields and inherent viscosities ranging between 0.24 and 0.46 dL g−1 and were characterized with FTIR, 1H NMR, CHN, and TGA techniques. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1248–1254, 2007
Copolymerization of ethylene and 1‐dodecene catalyzed by novel low‐Ti‐loading Ziegler–Natta catalysts and their microstructures
Authors: Zhao Zhenrong , Wang Li , Wang Jianfeng , Dong Xiaochen , Yu Haojie 
Published: January 2007

AbstractEthylene–1‐dodecene copolymers were synthesized with novel low‐Ti‐loading (0.8 wt %) Ziegler–Natta catalysts prepared by a one‐pot balling method. 13C‐NMR was applied for the quantitative determination of the composites and microstructures of the resultant ethylene–1‐dodecene copolymers. The results showed that (1) the ethylene–1‐dodecene copolymers obtained from both the MgCl2‐supported low‐Ti‐loading Ziegler–Natta catalyst and the MgCl2/SiO2‐bisupported low‐Ti‐loading Ziegler–Natta catalyst at a 0.6M 1‐dodecene concentration had high levels of 1‐dodecene and (2) most of the 1‐dodecene units were separated by ethylene units in the copolymer chains obtained from the MgCl2‐supported low‐Ti‐loading Ziegler–Natta catalyst, whereas there were some continuous 1‐dodecene repeat units in the copolymer chain obtained from the MgCl2/SiO2‐bisupported low‐Ti‐loading Ziegler–Natta catalyst. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1200–1204, 2007
Development of linseed oil based polyesteramide without organic solvent at lower temperature
Authors: Ahmad Sharif , Ashraf S. M. , Zafar Fahmina 
Published: January 2007

AbstractLinseed oil based polyesteramide was synthesized at lower temperature in the absence of organic solvent through condensation polymerization reaction [Sf‐LPEA]. In this reaction N,N‐bis(2‐hydroxyethyl) linseed oil fatty amide and phthalic anhydride were heated at temperature lower than their onset of melting points and the by‐product, such as water was removed by application of vacuum technique. This approach was employed to overcome the use of volatile organic solvents used during processing and application of resin, which are ecologically harmful. The solubility of Sf‐LPEA was checked in different polar and nonpolar solvents. The FTIR, 1H NMR, and 13C NMR spectral techniques were used to confirm the structure of Sf‐LPEA. The physicochemical, physicomechanical, and chemical resistance properties of the resin were investigated by standard methods. DSC and TGA were used to determine, respectively, the curing behavior and thermal stability of the resin. The comparative study of these properties of Sf‐LPEA with reported polyesteramide [LPEA], which are normally synthesized at higher temperature in organic solvent, was done. It was found that Sf‐LPEA exhibited improved physicomechanical, chemical resistance properties, and higher thermal stability compared with LPEA, and hence can find application as corrosion protective coating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1143–1148, 2007
Gloss and degradation of hydroxyl polyacrylic resin/hexamethylene‐1,6‐diisocyanate coatings under ultraviolet and natural‐exposure aging
Authors: Liu Can‐Pei 
Published: January 2007

AbstractReactive coatings of hydroxyl polyacrylic resin (HPAR) with hexamethylene‐1,6‐diisocyanate were carried out under accelerated 313‐nm ultraviolet (UV) aging for 2000 h and under natural exposure in Lhasa, Tibet, for 24 months. With UV irradiation and exposure time, the gloss changes in coatings with HPAR containing 3.0% or less hydroxyl groups decreased exponentially, whereas the gloss decay of coatings with HPAR containing over 4.5% hydroxyl groups decreased linearly. During 254‐nm UV aging, the gloss changes in coatings with HPAR containing 1.4% or less hydroxyl groups decreased as a Gaussian function. The weather resistance of a coating was correlated to the HPAR, UV irradiation, temperature, and humidity. Scanning electron microscopy indicated that there were degradation reactions and that some substance was lost in the matrix polymer during accelerated UV aging; then, uneven surfaces appeared and caused decreased gloss. Accelerated UV aging was faster than natural‐exposure aging, and the aging velocity of 254‐nm UV was 3–5 times faster than that of 313‐nm UV. Through the changes in the gloss, the aging tolerance of a coating could be monitored, and its aging resistance could also be predicted. The dynamic mechanical thermal analysis results showed that the coatings had good properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1271–1278, 2007
Effect of the particle size of Al2O3 on the properties of filled heat‐conductive silicone rubber
Authors: Zhou Wenying , Qi Shuhua , Tu Chunchao , Zhao Hongzhen , Wang Caifeng , Kou Jingli 
Published: January 2007

AbstractAn elastomeric thermal pad with a thermal conductivity of 1.45 W/m K, needed for the heat dissipation of microelectronics, was obtained with hybrid alumina of different particle sizes as a filler and silicone rubber (vinyl‐end‐blocked polymethylsiloxane) as the matrix. The effects of the amount, particle size, and mixing mass ratio of the filler particles on the thermal conductivity and mechanical properties of silicone rubber were investigated. The results indicated that the thermal conductivity of the rubber filled with larger particles was superior to that of the rubber filled with the smaller grain size, and the rubber incorporated with a mixture of hybrid particles at a preferable mass ratio exhibited higher thermal conductivity than the rubber for which a filler with only a single particle size was used. In addition, the surface treatment of the hybrid filler with 3‐methacryloyloxypropyltrimethoxysilane could increase the thermal conductivity of the composite rubber. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1312–1318, 2007
Preparation of unsaturated polyester–styrene beads using gamma irradiation and chemical polymerization routes for use in the recovery of some alkali metal ions
Authors: El‐Nahas H. H. , Khalil F. H. , Ibrahim G. M. , El‐Gammal B. 
Published: January 2007

AbstractSuspension polymerization of unsaturated polyester–styrene was carried out in different media using different routes of polymerization. The effects of matrix type and concentration hold up, viscosity, irradiation dose, and the agitation speed on the resultant polymer characteristics were examined. The formed beads were physically identified using scanning electron microscopy, hardness, and particle size analysis techniques. They were smooth having typical spherical surfaces; the beads diameters were in the range of about 5–200 μm. The size of the resin beads was found to decrease with increase in the concentration and viscosity of the dispersant and impeller speed. The resultant beads were applied in the recovery of Li+, Na+, K+, and Cs+ ions from acidic media. The distribution coefficients of the alkali metal ions were calculated; the order of selectivity was Li+ > Na+ > K+ > Cs+ in case of the chemically processed resin beads, while the selectivity lies in the order of Li+ < Na+ < K+ < Cs+ in case irradiation processed ones. Finally, the economics of production of the unsaturated polyester–styrene resins using different methodologies was studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1149–1160, 2007
Effects of ethylene content of poly(ethylene‐co‐vinyl alcohol) on diameter of fibers produced by melt‐electrospinning
Authors: Ogata Nobuo , Lu Gang , Iwata Toshiharu , Yamaguchi Shinji , Nakane Koji , Ogihara Takashi 
Published: January 2007

AbstractRodlike samples were made from four kinds of poly(ethylene‐co‐vinyl alcohol) (EVAL) pellets with different ethylene contents. From these rodlike samples, fibers were produced using a melt‐electrospinning system equipped with a CO2‐laser melting device. The effects on the fiber diameter of the ethylene content and the moisture regain of the rodlike samples were investigated. Furthermore, the physical properties of the fibers were investigated. The following conclusions were reached: (i) EVAL fibers having an average fiber diameter smaller than 1 μm can be obtained using the system developed; (ii) the diameter of EVAL fiber is influenced by the ethylene content and the moisture regain of the starting rods; (iii) the laser heating does not greatly decrease the melting point and the molecular weight of EVAL; and (iv) preferred crystal orientation can be seen in electrospun EVAL fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1368–1375, 2007
Dye flocculation using polyampholytes and polyelectrolyte‐surfactant nanoparticles
Authors: Petzold Gudrun , Schwarz Simona , Mende Mandy , Jaeger Werner 
Published: January 2007

AbstractIn this article, we report on the dye flocculation performance of polyampholytes containing hydrophobically modified cationic, hydrophilic nonionic, and anionic monomer units, always with an excess of cationic charges. The results are compared with homopolymers and with those obtained using nonstoichiometric polyelectrolyte–surfactant complex (PSC) dispersions with adjustable surface charge density. The polyampholytes as well as the PSC can successfully remove the dye Celliton Fast Blue (Dispers blue 3). The efficiency of dye separation is mainly influenced by the charge of polymers or complexes, demonstrating that charge neutralization is one flocculation mechanism. However, PSC, which are almost neutral, are also able to remove the dye due to their size and structure. In this case, the degree of dye removal is a little bit better and the so‐called flocculation window is broader as in the case of charge neutralization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1342–1349, 2007
Architectural gear ratio and muscle fiber strain homogeneity in segmented musculature
Authors: Azizi Emanuel , Brainerd Elizabeth L. 
Published: January 2007

AbstractIn the segmented axial musculature of fishes and amphibians, the patterns of muscle fiber shortening depend on both the orientation of muscle fibers relative to the long axis of the body as well as the distance of fibers from the neutral axis of bending (vertebral column). In this study we use the relatively simple architecture of salamander hypaxial muscles to explore the separate and combined effects of these morphological features on muscle fiber strains during swimming. In Siren lacertina the external oblique (EO) muscle has more obliquely oriented muscle fibers and is located further from the neutral axis of bending than the internal oblique (IO) muscle. To examine the effect of muscle fiber angle on strain patterns during swimming, we used sonomicrometry to quantify architectural gear ratio (AGR=longitudinal strain/fiber strain) in these two hypaxial muscles. By comparing the muscle fiber strains and shortening velocities of the EO and IO during swimming, we test whether variation in mediolateral position of the muscle layers is counteracted by their differences in AGR. We find that despite substantial differences in mediolateral position, the EO and IO undergo similar fiber strains and shortening velocities for a given amount of axial bending. Our results show that variation in muscle fiber angle acts to counteract differences in mediolateral position, thereby minimizing variation in muscle fiber strain and shortening velocity during swimming. These results highlight the significance of both muscle architecture and muscle moment arms in determining the fiber strains required for a given movement. J. Exp. Zool. 307A, 2007. © 2007 Wiley‐Liss, Inc.
Absorption of tetraethylammonium (TEA+) by perfused lobster intestine
Authors: Piersol Megan C. , Sterling Kenneth M. , Ahearn Gregory A. 
Published: January 2007

AbstractThe organic cation, tetraethylammonium (TEA+), is actively secreted by mammalian nephrons and crustacean urinary bladders by similar processes in both animal groups. These mechanisms consist of a basolateral Organic Cation Transporter (OCT family) that employs the transmembrane electrical potential as a driving force for organic cation uptake from the blood and a brush border secondary active transport process that exchanges luminal protons for TEA+. The present study examined the nature of 14C‐TEA+ transport across the perfused intestinal epithelium of the American lobster, Homarus americanus, to ascertain whether the gut complemented the kidneys in the clearance of these organic metabolites from the blood. Unidirectional mucosa to serosa (M to S) 14C‐TEA+ fluxes in anterior and posterior intestine were hyperbolic functions of luminal [TEA+] and significantly (P<0.01) exceeded the respective serosa to mucosa (S to M) fluxes. Luminal quinine (1 mM) significantly (P<0.05) inhibited M to S flux of the organic cation, while serosal addition of the drug had no effect on S to M transfer of TEA+. Reducing serosal pH from 7.20 to 6.02 significantly (P<0.01) stimulated M to S transfer of 0.1 mM 14C‐TEA+, but significantly (P<0.05) lowered S to M transfer of the metabolite.Addition of 2.0 mM unlabelled serosal TEA+ trans‐stimulated the M to S flux of 0.1 mM 14C‐TEA and doubled the transfer rate of the organic cation from lumen to blood compared to its transport in the absence of TEA+ in the bath. Results suggest that this organic cation is absorbed across lobster intestine by the combination of a brush border OCT‐1‐like transporter coupled with a basolateral H+/TEA+ exchanger. A working model is presented for intestinal organic cation absorption in crustaceans and compared to the secretory transport model for this class of metabolites previously reported for crustacean and mammalian kidneys. J. Exp. Zool. 307A, 2007. © 2007 Wiley‐Liss, Inc.
Continuous Versus Interrupted Suture for End-To-End Biliary Anastomosis During Liver Transplantation Gives Equal Results†
Authors: Castaldo Eric T. , Pinson Wright C. , Feurer Irene D. , Wright Kelly J. , Gorden Lee D. , Kelly Beau S. , Chari Ravi S. 
Published: January 2007

Abstract

Biliary complications following orthotopic liver transplantation have been reported in 10% to 30% of patients. Most surgeons perform an end-to-end choledochocholedochostomy with interrupted sutures for biliary reconstruction. The goal of this study was to compare biliary complications between interrupted suture (IS) and continuous suture (CS) techniques during liver transplantation in which an end-to-end choledochocholedochostomy over an internal biliary stent was performed. A retrospective cohort study of 100 consecutive liver transplants occurring between December 2003 and July 2005 was conducted. An end-to-end choledochocholedochostomy over an internal biliary stent was performed during liver transplantation. Data were analyzed using Kaplan-Meier methods, t tests, and chi-square tests of proportions. IS and CS techniques were used in 59 and 41 patients, respectively, for biliary reconstruction during liver transplantation. Mean follow-up time for the CS group was 17 ± 8 months and 15 ± 7 months for the IS group (P = .21). The overall biliary complication rate was 15%. There was no difference in the proportion of leaks (CS = 7.3%, IS = 8.5%; P = .83) or strictures (CS = 9.8%, IS = 5.1%; P = .37) between groups. Kaplan-Meier event rates show no difference in leaks (P = .79), strictures (P = .41), graft survival (P = .52), and patient survival (P = .32) by anastomosis type. In conclusion, there was no difference in biliary complications, graft survival, or patient survival between the 2 groups. CS and IS techniques for biliary reconstruction during liver transplantation yield comparable outcomes. Liver Transpl 13:234–238, 2007. © 2007 AASLD.
Liver Retransplantation for Primary Nonfunction
Authors: Uemura Tadahiro , Randall Henry B. , Sanchez Edmund Q. , Ikegami Toru , Narasimhan Gomathy , McKenna Greg J. , Chinnakotla Srinath , Levy Marlon F. , Goldstein Robert M. , Klintmalm Goran B. 
Published: January 2007

Abstract

Initial graft function following liver transplantation is a major determinant of postoperative survival and morbidity. Primary graft nonfunction (PNF) is uncommon; however, it is one of the most serious and life-threatening conditions in the immediate postoperative period. The risk factors associated with PNF and short-term outcome have been previously reported, but there are no reports of long-term follow-up after retransplant for PNF. At our institution, 52 liver transplants had PNF (2.22%) among 2,341 orthotopic liver transplants in 2,130 patients from 1984 to 2003. PNF occurred more often in the retransplant setting. Female donors, donor age, donor days in the intensive care unit, cold ischemia time, and operating room time were significant factors for PNF. Patient as well as graft survival of retransplant for PNF was not different compared to retransplant for other causes. However, PNF for a second or third transplant did not demonstrate long-term survival, and hospital mortality was 57%. In conclusion, retransplant for PNF in the initial transplant can achieve relatively good long-term survival; however, if another transplant is needed in the setting of a second PNF, the third retransplant should probably not be done due to poor expected outcome. Liver Transpl 13:227–233, 2007. © 2007 AASLD.
Factors Influencing the Progression of Fibrosis in Patients with Recurrent Hepatitis C After Liver Transplantation Under Antiviral Therapy
Authors: Walter Thomas , Dumortier Jérôme , Guillaud Olivier , Hervieu Valérie , Scoazec Jean-Yves , Boillot Olivier 
Published: January 2007

Abstract

Recurrent hepatitis C after liver transplantation (LT) is a major problem, since up to 30% of patients develop cirrhosis only 5 years after LT in the absence of antiviral therapy. The aim of this study was to examine the rate of progression of fibrosis and its associated risk factors in patients submitted to an early antiviral treatment post-LT. Included in the study were 105 patients submitted to LT between September 1990 and December 2004, 70 of whom were treated with interferon and/or ribavirin. A total of 939 liver biopsies were studied. The median fibrosis stage was 0.8 after 1 year post-LT, 1.1 after 3 years, 1.3 after 5 years, and 1.5 after 10 years. LT recipients with fibrosis >2 (13% at 10 years) had a significantly reduced survival rate (63% vs. 87% at 10 years, P = 0.03). Univariate analysis disclosed that recipient male gender, antiviral therapy before LT, LT after 1998, induction immunosuppressive regimen including tacrolimus, induction immunosuppressive regimen including mycophenolate (or without azathioprine), and short duration of prednisolone (<12 months) were significantly associated with progression of fibrosis. In a multivariate analysis, recipient male gender (P = 0.04), antiviral treatment before LT (P = 0.001), and initial immunosuppressive regimen without azathioprine (P = 0.03) were associated with progression of fibrosis. In conclusion, our study has documented that fibrosis progression is not linear over time and that occurrence of severe fibrosis is related to previously described factors related to immunosuppressive regimen or donor age and also to a past history of pre-LT antiviral therapy. Liver Transpl 13:294–301, 2007. © 2007 AASLD.