bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of monomethyl poly(ethylene glycol)‐g‐chitosan copolymers with various degrees of substitution: Their ability to encapsulate and condense plasmid DNA
Authors: Zhang Wei , Pan Shirong , Zhang Xuan , Luo Xin , Du Zhuo 
Published: February 2008

AbstractChitosan (CS) has great potential as a nonvirus gene delivery vector, but its application is limited because of poor water solubility. Monomethyl poly(ethylene glycol) (mPEG)‐graft‐CS copolymers were synthesized by the reaction of mPEG–aldehyde (oxidized mPEG) with amino groups on CS chains; they showed enhanced solubility in water. Copolymers with various mPEG degrees of substitution (DS) and CS molecular weights were obtained, and their capabilities of DNA encapsulation were compared through gel retardation assay and particle size and ζ potential measurements. The effects of different ratios of primary amines on CS to the phosphate groups on DNA (N/P ratios), DS, and molecular weights on particle size and encapsulation efficiency were investigated. The results show that high N/P ratios and proper DS were necessary for the formation of well‐distributed complex particles. Among all of these samples, mPEG (3.55)–CS (50 kDa)/DNA complexes [where the parentheses following mPEG indicate DS (%), and the parentheses following CS indicate the molecular weight of CS] raised the ζ potential from negative to positive most quickly, yielded the smallest particle size, and were retarded in agarose gel at the lowest N/P ratio; this indicated the best efficiency of DNA encapsulation. On the contrary, mPEG (0.80)–CS (50 kDa)/DNA complexes raised the ζ potential to positive most slowly, fluctuated around the value 0 from N/P ratios of 15 : 1 to 30 : 1, and were retarded in agarose gel at the highest N/P ratio; this indicated the lowest efficiency of encapsulating plasmids. Copolymers with desirable efficiencies of DNA encapsulation could be promising gene carriers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of solvent on the chain conformation and cure behavior of phenolic resin
Authors: Yan Zhang , Yujian Liu , Qi He , Zhewen Han 
Published: February 2008

AbstractThe research indicates that in comparison with other solvents, such as ethanol, propanol, butyl alcohol and acetone, which are usually selected as the solvent in phenolic solution, methanol can increase curing rate and enhance crosslinking density of phenolic resins. Therefore, the chain conformations of resole dissolved in different solvents are investigated by using viscosity method. It shows that the chain conformation of resoles changes from loose coil to compact ball, as the strength of hydrogen bond between resole and solvent drops along with the decrease of polarity of solvents. The transition of the chain conformation causes the decrease of reaction probability and reaction rate between functional groups of resoles. The number of unreacted molecules increases, and the crosslinking density of cured resins decreases. The differential scanning calorimetric analysis shows that compared with the resins in methanol, ethanol, propanol, and butyl alcohol, exothermic peak of resole in acetone is obviously wider, and its peak exothermic temperature is lower. Both optical microscope pictures and atomic force microscope pictures demonstrate that the crosslinking density of resins in methanol is higher than those in other solvents. The research concludes that the type of solvent has a great influence on the curing rate and curing degree of resoles. © 2008 Wiley Periodicals, Inc. JAppl Polym Sci, 2008
Compatibility, rheological, and thermal properties of the melt blends of PEN (HQ/PP) with PEN (HQ/RS)
Authors: Li Cao , Gao Nian , Liu Xiaobo 
Published: February 2008

AbstractTwo kinds of polyarylene ether nitriles (PEN) copolymers PEN (HQ/PP) and PEN (HQ/RS) were synthesized using 2,6‐dicholorobenzonitrile (DCBN) with equal molar of phenolphthalein (PP) and hydroquinone (HQ), DCBN with equal molar of HQ and resorcin (RS), respectively. The melt‐mixed blends of two PENs over the complete composition range were characterized by dynamic mechanical analyses (DMA), tensile testing, scanning electronic microscopy (SEM), and capillary rheometer test for their compatibility, thermal, mechanical, and melt flow properties study. DMA show a considerable compatibility between the two PENs. Morphology examinations reveal good component dispersion and strong interface adhesion. The capillary rheometer test found that the blending of PEN (HQ/RS) enhanced the fluidity of the PEN (HQ/PP)/PEN (HQ/RS) blends by reducing its viscosity, which is beneficial to the processability of PEN (HQ/PP). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of the composition of α‐MSAN copolymer on the miscibility of PVC/α‐MSAN blends
Authors: Zhang Lixia , Sun Shulin , Ren Liang , Zhang Fangfang , Zhang Mingyao , Zhang Huixuan 
Published: February 2008

AbstractA series of α‐methylstyrene, styrene, and acrylonitrile (α‐MSAN) copolymers with different acrylonitrile (AN) contents were synthesized by altering α‐MSt, St, and AN ratios with emulsion copolymerization method. By melt‐blending these copolymers with PVC resin and di‐isooctyl phthalate (DOP), PVC/α‐MSAN, and PVC/α‐MSAN/DOP blends were prepared. The miscibility and morphology of the blends were investigated by dynamic mechanical analysis (DMA) and scanning electron microscopy. The PVC is immiscible with SAN by melt‐mixing, whereas PVC is miscible with α‐MSAN (α‐MSt/St = 1/1) if AN weight percent is within the window range of 20–25 wt %, and α‐MSAN (not containing St) with 35 wt % AN is miscible with PVC even when they are blended by melt‐mixing. Replacement of styrene with α‐methylstyrene widens the miscibility window with PVC. The miscibility of PVC/α‐MSAN blends is substantially improved with the increasing α‐MSt content in α‐MSAN copolymer containing identical AN content. When DOP was introduced into the PVC/α‐MSAN (α‐MSt/St = 1/1) blends, a single tan δ peak over room temperature in DMA detection is found as AN content in α‐MSAN copolymer is within the range of 15–25 wt %, and SEM observation also shows that the blends are homogeneous. When the AN content in α‐MSAN copolymer is over 35 wt %, the presence of DOP causes the phase domain extended. The phase domain size of the PVC/α‐MSAN/DOP blends intensively depends on AN content in α‐MSAN copolymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Structural characteristics and selected properties of polyacrylonitrile nanofiber mats
Authors: Borhani Sedigheh , Hosseini Seyed Abdolkarim , Etemad Seyed Gholamreza , Militký Jiří 
Published: February 2008

AbstractIn electrospinning, the structure of nanofibers, which is affected by polymer solution parameters and processing conditions, influences the physical characteristics of nanofiber mats. In this study, under optimum conditions of electrospinning, the concentration of polyacrylonitrile (PAN) was changed from 11 to 15 wt %, and its effects on the nanofiber diameter and surface porosity of nanofiber mats were studied. The results showed that increasing the PAN polymer concentration enhanced the nanofiber diameter but reduced the surface porosity of nanofiber mats. Because the diameter and surface porosity are parameters that possess mutual effects, a structural parameter (Q) was introduced, and then its relation to some of the physical characteristics, such as the air permeability and surface roughness, was investigated. To evaluate the surface roughness, atomic force microscopy (AFM) and entropy (ENT) methods were used. The surface roughness of nanofiber mats was measured by AFM in a surface noncontact mode and by ENT with an image analysis technique and co‐occurrence matrix. The correlation coefficient of the surface roughness obtained from these two methods was 94%. The results also present a strong dependence between Q and the surface roughness and air permeability of nanofiber mats. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Cryostructuring of polymer systems. XXIX. Preparation and characterization of supermacroporous (spongy) agarose‐based cryogels used as three‐dimensional scaffolds for culturing insulin‐producing cell aggregates
Authors: Lozinsky Vladimir I. , Damshkaln Lilija G. , Bloch Konstantin O. , Vardi Pnina , Grinberg Natalia V. , Burova Tatiana V. , Grinberg Valerij Y. 
Published: February 2008

AbstractSupermacroporous (spongy) agarose‐based cryogels were prepared by a two‐step freezing procedure (freezing at −30°C followed by incubation at a warmer subzero temperature) and subsequent thawing. The cryogels were formed as cylinders in plastic syringes and as platelike samples in flat metal molds. The characteristic feature of the gel matrices thus obtained was their heterogeneous spongelike morphology with a system of interconnected gross (50–250‐μm and larger) pores. The influence of the cryogenic processing regimes on the properties and porous morphology of such agarose cryogels was explored by flow‐through analysis, optical microscopy, thermometry, and high‐sensitivity differential scanning calorimetry. These biocompatible, spongelike matrices were used as three‐dimensional scaffolds for culturing insulin‐producing rat insulinoma cells self‐assembled in multicellular spherical aggregates (pseudoislets). The cell morphology and functional activity of such pseudoislets indicate that supermacroporous agarose‐based cryogels can be useful as a tool for engineering biohybrid insulin‐producing tissue. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Preparation of temperature‐sensitive poly(N‐isopropylacrylamide)/β‐cyclodextrin‐grafted polyethylenimine hydrogels for drug delivery
Authors: Zhang Jian‐Tao , Xue Ya‐Nan , Gao Fa‐Zhi , Huang Shi‐Wen , Zhuo Ren‐Xi 
Published: February 2008

AbstractIn this study, novel thermally sensitive semi‐interpenetrating polymeric network hydrogels composed of poly(N‐isopropylacrylamide) (PNIPAAm) and β‐cyclodextrin‐grafted polyethylenimine were prepared by radical polymerization. Compared to normal PNIPAAm hydrogels, the semi‐interpenetrating network hydrogels had a higher swelling ratio at room temperature and exhibited faster shrinking kinetics when the temperature was elevated to above the lower critical solution temperature. Propranolol as a model drug was loaded into the gels, and the release results show that compared to that of the normal PNIPAAm hydrogel, the release time of propranolol from the cyclodextrin‐containing gel was prolonged. These improved drug‐release properties may have been due to the formation of inclusion complexes between the drug molecules and cyclodextrin groups. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Photostability of isotactic polypropylene containing monoazo pigment
Authors: Ahmadi Zahra , Kish Mohammad Haghighat , Freeman Harold , Kotek Richard , Katbab Ali Asghar 
Published: February 2008

AbstractThe photodegradation of isotactic polypropylene (PP) films containing a monoazo pigment and hindered amine light stabilizers (HALS) has been undertaken. PP films were exposed to medium pressure mercury lamp radiation in the laboratory for periods of up to 8 weeks and the degree of degradation (oxidation/deterioration) was examined using FTIR spectroscopy and differential scanning calorimetry (DSC) as well as by measuring changes in the mechanical properties, contact angle, and density. The results of these measurements indicate that unstabilized PP films degraded after only 240‐h irradiation. By adding an organic pigment to PP films along with antioxidant and HALS, the photostability of PP films increased to the 1500‐h level. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Investigation of the water and fuel exposure characteristics of aircraft fuel tank sealants and the effect on their glass transition temperature
Authors: Giannis S. , Adams R. D. , Clark L. J. , Taylor M. A. 
Published: February 2008

AbstractThe water and fuel absorption and desorption characteristics have been studied of aircraft fuel tank sealants. The sealants were an epoxy‐cured polythioether and a MnO2‐cured polysulphide. The effect of the water and fuel exposure on the glass transition temperature was also investigated. Water diffusion was found to be Fickian for the polythioether sealant and the equilibrium plateau level was found not to be dependent on the immersion temperature. On the other hand, the polysulphide sealant demonstrated a clear non‐Fickian water uptake characteristic, with large uptake levels, which were attributed to water droplet formation in the volume of the bulk sealant. The glass transition temperature of the polythioether sealant was not affected by the presence of water (∼ 4% by weight) while that of the polysulphide was increased by ∼ 8°C for a water uptake level of ∼ 50% by weight. Fuel absorption followed a very similar trend for both sealants with the weight gain demonstrated an early maximum followed by a subsequent weight decrease, indicating leaching of fuel soluble fractions, until equilibrium was reached. The presence of fuel acted as plasticizer for the sealants; depressing their glass transition temperature by ∼ 10°C. Tests on dried samples have shown that the effect on the glass transition temperature was reversible. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Proteomic analysis to characterize differential mouse strain sensitivity to cadmium‐induced forelimb teratogenesis
Authors: Chen Haiyan , Boontheung Pinmanee , Ogorzalek Loo Rachel R. , Xie Yongming , Loo Joseph A. , Rao Jian‐yu , Collins Michael D. 
Published: February 2008

AbstractBACKGROUND:Cadmium ion (Cd2+) is a ubiquitous environmental contaminant, and it is a potent teratogen in mice. An intraperitoneal dose of 4 mg/kg of CdCl2 at gestational day 9 causes forelimb ectrodactyly in the C57BL/6N mouse strain, but the SWV/Fnn strain is resistant. The objective of this study was to identify differentially displayed proteins in two target tissues for cadmium teratogenesis, and to derive hypotheses regarding the mechanisms involved in the murine strain difference in Cd‐induced forelimb ectrodactyly.METHODS:The global proteomics strategy used two‐dimensional polyacrylamide gel electrophoresis for protein separation, and MALDI‐TOF‐MS and LC‐MS/MS for protein identification, to compare and identify proteins in forelimb buds and yolk sacs from the two mouse strains following Cd administration.RESULTS:More than 1,000 protein spots were detected by two‐dimensional polyacrylamide gel electrophoresis in day 10.0 mouse forelimb buds and yolk sacs. Thirty‐eight proteins had identifiable differences in abundance levels in Cd‐treated forelimb buds between the two strains. Of those 38 proteins, 14 could be associated with the unfolded protein response process and seven are associated with actin polymerization. The proteins that were found to be differentially abundant between the strains in yolk sacs that were exposed to CdCl2 were predominantly different than the proteins detected differentially in the limb buds of the two strains with an overlap of approximately 20%.CONCLUSIONS:These patterns of differentially displayed proteins rationalize a hypothesis that the differential murine strain response to cadmium‐induced forelimb ectrodactyly is due to differences in their pathways for the unfolded protein response and/or actin polymerization. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.
Increasing therapeutic exercise participation by individuals with acquired brain injury using self‐recording and reinforcement
Authors: Maki Amber L. , Rudrud Eric H. , Schulze Kim A. , Rapp John T. 
Published: February 2008

AbstractThe purpose of this study was to evaluate the effects of self‐recording and contingent reinforcement on exercise participation by four adults with acquired brain injury. The results indicate that self‐recording and contingent reinforcement increased participation in stretching, aerobic, and weight‐lifting activities for each participant. The results also indicate that each participant was able to accurately self‐record his or her exercise participation. Possible operant conceptualizations for the observed behavior change, as well as limitations to the results, are briefly discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Clinical outcome and long-term survival in 118 consecutive patients with neuroendocrine tumours of the pancreas
Authors: Fischer L , Kleeff J , Esposito I , Hinz U , Zimmermann A , Friess H , Büchler M W 
Published: February 2008

Abstract

Background
The aim was to assess the clinical relevance of the World Health Organization and tumour node metastasis (TNM) classifications in patients with pancreatic neuroendocrine tumours (pNETs).

Methods
Prospectively collected data from 118 consecutive patients with a pNET receiving surgical intervention were analysed.

Results
Forty-one patients had well differentiated neuroendocrine tumours, 64 had well differentiated neuroendocrine carcinomas and 13 had poorly differentiated neuroendocrine carcinomas. Five-year survival rates were 95, 44 and 0 per cent respectively (P &lt; 0·001). There was no difference in survival after R0 and R1/R2 resections in patients with neuroendocrine carcinomas (P = 0·905). In those with well differentiated neuroendocrine carcinomas, any resection and having a clinically non-functional tumour significantly increased survival (P = 0·003 and P = 0·037 respectively). The TNM stage was I in 37 patients, II in 15 patients, III in 32 patients and IV in 34 patients. There were significant differences in 5-year survival between stage I and II (88 and 85 per cent respectively) and stage III and IV (31 and 42 per cent respectively) (P = 0·010).

Conclusion
Both classifications accurately reflect the clinical outcome of patients with pNET. The resection status may not be critical for long-term survival in patients with pNET.
Child welfare workers' practice in cases involving domestic violence
Authors: Bourassa Chantal , Lavergne Chantal , Damant Dominique , Lessard Geneviève , Turcotte Pierre 
Published: February 2008

AbstractThis paper reports the findings of an exploratory and qualitative study of child welfare workers' practice in cases involving domestic violence. The research aimed to focus on child welfare workers' interventions with families experiencing domestic violence, elements influencing the child welfare workers' decisions, and the factors facilitating and creating obstacles for intervention. An analysis of the qualitative data showed that child welfare workers have different ways of intervening in cases involving domestic violence. Also, the interventions were especially centred on women victims of violence and they were held responsible for protecting their children. Finally, the dilemmas and difficulties which child welfare workers face in these cases are discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Trends in US Army child maltreatment reports: 1990–2004
Authors: McCarroll James E , Fan Zizhong , Newby John H , Ursano Robert J 
Published: February 2008

AbstractWe present the victim rates and severity of child maltreatment in US Army families by the sex of the child and parent from 1990–2004. Neglect rates decreased from a high point in 1991 to a low in 2000, but by 2004 the rates had increased to about the 1991 level. During two large‐scale deployments of the US Army to the Middle East (1991 and 2002–2004), the rates of neglect increased. Neglect rates were highest for the youngest children and decreased as age increased. Physical abuse rates decreased from 1990–2004, but the decline was slowed during 2001–04. Physical abuse was more severe by male offenders. Emotional abuse showed wide fluctuations in rates. Emotional abuse rates were similar for boys and girls up to age 11, but the rates for older girls were higher. Sexual abuse had the lowest rates throughout the time of this report, decreasing from about 0.5/1000 to about 0.1/1000. The rates of physical abuse and neglect were generally higher for boys than for girls up to the teenage years when the rates reversed. Male offenders were more likely to maltreat children (even excluding sexual abuse) than were female offenders and offenders of both sexes were more likely to abuse male children. We provide suggestions for practice, prevention and research in child maltreatment. Published in 2008 by John Wiley & Sons, Ltd.
[Ru(bpy)3]2+‐Doped Silica Nanoparticles within Layer‐by‐Layer Biomolecular Coatings and Their Application as a Biocompatible Electrochemiluminescent Tag Material
Authors: Wei Hui , Liu Jifeng , Zhou Lingling , Li Jing , Jiang Xiue , Kang Jianzhen , Yang Xiurong , Dong Shaojun , Wang Erkang 
Published: February 2008

Abstract[Ru(bpy)3]2+‐doped silica (RuSi) nanoparticles were synthesized by using a water/oil microemulsion method. Stable electrochemiluminescence (ECL) was obtained when the RuSi nanoparticles were immobilized on a glassy carbon electrode by using tripropylamine (TPA) as a coreactant. Furthermore, the ECL of the RuSi nanoparticles with layer‐by‐layer biomolecular coatings was investigated. Squential self‐assembly of the polyelectrolytes and biomolecules on the RuSi nanoparticles gave nanocomposite suspensions, the ECL of which decreased on increasing the number of bilayers. Moreover, factors that affected the assembly and ECL signals were investigated. The decrease in ECL could be assigned to steric hindrance and limited diffusion of the coreactant molecules in the silica matrix after they were attached to the biomolecules. Since surface modification of the RuSi nanoparticles can improve their biocompatibility and prevent leaking of the [Ru(bpy)3]2+ ions, the RuSi nanoparticles can be readily used as efficient and stable ECL tag materials in immunoassay and DNA detection.
Catalytic Asymmetric Aziridination with Borate Catalysts Derived from VANOL and VAPOL Ligands: Scope and Mechanistic Studies
Authors: Zhang Yu , Desai Aman , Lu Zhenjie , Hu Gang , Ding Zhensheng , Wulff William D. 
Published: February 2008

AbstractAn extended study of the scope and mechanism of the catalytic asymmetric aziridination of imines with ethyl diazoacetate mediated by catalysts prepared from the VANOL and VAPOL ligands and triphenylborate is described. Nonlinear studies with scalemic VANOL and VAPOL reveal an essentially linear relationship between the optical purity of the ligand and the product suggesting that the catalyst incorporates a single molecule of the ligand. Two species are present in the catalyst prepared from B(OPh)3 and either VANOL or VAPOL as revealed by 1H NMR studies. Mass spectral analysis of the catalyst mixture suggests that one of the species involves one ligand molecule and one boron atom (B1) and the other involves one ligand and two boron atoms (B2). The latter can be formulated as either a linear or cyclic pyroborate and the 11B NMR spectrum is most consistent with the linear pyroborate structure. Several new protocols for catalyst preparation are developed which allow for the generation of mixtures of the B1 and B2 catalysts in ratios that range from 10:1 to 1:20. Studies with catalysts enriched in the B1 and B2 species reveal that the B2 catalyst is the active catalyst in the VAPOL catalyzed asymmetric aziridination reaction giving significantly higher asymmetric inductions and rates than the B1 catalyst. The difference is not as pronounced in the VANOL series. A series of 12 different imines were surveyed with the optimal catalyst preparation procedure with the finding that the asymmetric inductions are in the low to mid 90s for aromatic imines and in the mid 80s to low 90s for aliphatic imines for both VANOL and VAPOL catalysts. Nonetheless, the crystallinity of the N‐benzhydryl aziridines is such that nearly all of the 12 aziridine products screened can be brought to >99 % ee with a single recrystallization.