bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural and Chemical Effects of Plasma Treatment on Close‐Packed Colloidal Nanoparticle Layers
Authors: Gehl Bernhard , Frömsdorf Andreas , Aleksandrovic Vesna , Schmidt Thomas , Pretorius Angelika , Flege Jan‐Ingo , Bernstorff Sigrid , Rosenauer Andreas , Falta Jens , Weller Horst , Bäumer Marcus
Published: July 2008

The interaction of nitrogen, oxygen, and hydrogen plasmas with spin‐coated arrays of colloidal cobalt–platinum particles was investigated with a large variety of microscopic and spectroscopic techniques. It could be demonstrated that the organic ligands of the nanoparticles can be completely removed. Yet, due to the short (∼1.6 nm) interparticle distances within the layers, strong degradation and sintering effects are observed after hydrogen and nitrogen plasma treatments. In the case of oxygen plasma, the shape and size of the individual particles are unaffected and can be preserved, even if a short hydrogen plasma is subsequently applied to reduce the particles back to their metallic state. Nevertheless, the mesoscopic order of the particle arrays is slightly decreased as observed by the breakup of larger ordered areas into smaller domains forming island–trench structures. Probing the surface chemistry of the particles with temperature programmed desorption, a rather complex surface chemistry is found to result from the plasma treatments. The first TPD spectrum after the cleaning process with oxygen and subsequent hydrogen plasmas reveals that the particles are loaded with adsorbed and implanted hydrogen. After removal of this hydrogen, subsequent TPD spectra using CO as a probe molecule, show broad signals between 190 and 360 K pointing to nonmetallic surface properties. While the platinum was found to be completely reduced, XPS measurements reveal a remaining fraction of oxidic cobalt species which are enriched at the surface. Thus, although the structure of the close‐packed Co–Pt nanoparticle arrays can be qualitatively preserved during plasma‐based ligand removal, the treatment leads to a complex materials system the chemical properties of which are influenced by the particle components, the substrate, and the plasma media.
Electropolymerized Self‐Assembled Monolayers of a 3,4‐Ethylenedioxythiophene‐Thiophene Hybrid System
Authors: Oçafrain Maiténa , Tran Truong Khoa , Blanchard Philippe , Lenfant Stéphane , Godey Sylvie , Vuillaume Dominique , Roncali Jean
Published: July 2008

Self‐assembled monolayers (SAMs) of a conjugated bithiophenic system connected to an alkanethiol chain have been deposited on gold surface. The electroactive bithiophenic system involves a 3,4‐ethylenedioxythiophene (EDOT) unit and a thiophene ring on which an alkanethiol is attached at the internal β‐position via a sulfide linkage. The analysis of the structure of the SAMs by IR spectroscopy, ellipsometry, contact angle measurement and X‐ray photoelectron spectroscopy (XPS) provides consistent results indicating compact monolayers in which the alkyl linkers are arranged in an almost vertical fashion while the bithiophenic‐conjugated systems are essentially parallel to the surface. Cyclic voltammetry shows that application of a few potential scans to SAMs immersed in a medium containing only a supporting electrolyte leads to the typical electropolymerization curves while the CV of the electrooxized monolayer exhibits a reversible cyclic voltammogram characteristic of a stable electroactive extended conjugated system. The characterization of the electropolymerized monolayers by IR spectroscopy, ellipsometry, contact angle measurement, and XPS indicates compact monolayers. The analysis of the current voltage characteristics of the monolayers by conducting AFM before and after electrooxidation shows that the enhancement of the effective conjugation resulting from electropolymerization leads to a significant increase of the transport properties.
Social stressors, mental health, and physiological stress in an urban elite of young Afghans in Kabul
Authors: Panter‐Brick Catherine , Eggerman Mark , Mojadidi Aman , McDade Thomas W.
Published: July 2008

Afghanistan provides a unique setting in which to appraise psychosocial stress, given the context of persistent insecurity and widening economic inequality. In Kabul, people experience widespread frustrations, hinging on restricted opportunities for social advancement, education, and employment. We appraised social aspirations, every‐day stressors, psychosocial distress, and mental health problems for a random sample of 161 male and female students at Kabul University. The survey featured both existing and newly‐developed instruments (Self‐Reported Questionnaire SRQ‐20; Afghan Symptom Checklist; Afghan Daily Stressor Scale; and Social Aspirations and Frustrations), implementing both internationally‐used and culturally‐grounded measures of mental health assessment. We also included indicators of physical health (blood pressure, immune responses to Epstein‐Barr virus (EBV), C‐reactive protein, and body mass index), to map physiological function with reported psychosocial distress. This young, urban elite expressed major feelings of frustrations, related to physical, economic, social, and political stressors of day‐to‐day life in Kabul. There were striking gender differences for psychosocial and physiological markers of wellbeing; specifically, women showed poorer mental health (SRQ‐20, P = 0.01) and elevated EBV antibody titers (P = 0.003). Both diastolic blood pressure (P = 0.018) and EBV (P = 0.038) were associated with a subscale of family stressors among women, but not among men, consistent with women's social vulnerabilities to stressful family dynamics. This is the first study to integrate approaches from anthropology, cross‐cultural psychiatry, and human biology to document social stressors, psychosocial distress, and physiological wellbeing in the challenging setting of present‐day Afghanistan. Am. J.Hum. Biol., 2008. © 2008 Wiley‐Liss, Inc.
Preparation of magnetic nanospheres from a reverse microemulsion stabilized by a block copolymer surfactant
Authors: Chen Zhiming , Jiao Zhen , Li Zhiqiang
Published: July 2008

A new method for the preparation of magnetic nanospheres is reported. It involved the dispersion of an aqueous phase containing Fe3+, Fe2+, or/and Ni2+ ions into droplets in an organic medium with an amphiphilic block copolymer, which was synthesized through atom transfer radical polymerization at a lower temperature (70°C) and was then sulfonated by sodium hydrogen sulfite in tetrahydrofuran as a surfactant. A reduction was carried out in the water pool as a microreactor, which resulted in the yielding of polymer/magnetite particles. The size of the prepared spheres could be tuned up by variation of the preparation conditions, including the stirring speed, copolymer content, and so on. The average diameter was homogeneous and was about 10 nm. The magnetic nanospheres, whose saturation magnetization of magnetic nanoparticles of 3.8 × 10−3 emu/g was less than their bulk counterparts, exhibited characteristics of superparamagnetism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Microencapsulation of hydrophilic solid powder as fire retardant agent with epoxy resin by droplet coalescence method
Authors: Takahashi Masanori , Taguchi Yoshinari , Tanaka Masato
Published: July 2008

To give water resistance to Bistetrazol–diammonium (BHT–2NH3) as a fire retardant agent, microencapsulation with epoxy resin was tried by the droplet coalescence method. In this method, two kinds of epoxy resin droplets were prepared; one is the larger epoxy resin droplet containing BHT–2NH3 as a core material and the other the smaller droplets containing Imidazole as a gelation agent. The larger epoxy resin droplets were made to coalesce with the many smaller droplets during the microencapsulation process to prepare microcapsules. In the experiment, the agitation velocities for preparation of the droplets and for coalescence were mainly changed. With increase in the impeller speed, the content of core material increased, became maximum because of increase in the coalescence frequency, and then decreased because of breakup of droplets. With increase in the impeller speed, the leakage ratio of core material decreased, became minimum, and then increased. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.
Preparation and magnetic properties of novel supramolecular polymeric complexes containing bithiazole rings
Authors: Lin Weihong , Sun Weilin , Yang Jun , Shen Zhiquan
Published: July 2008

The preparation and magnetism of two supramolecular polymeric complexes, DABT/PAA‐Ni2+ and DABT/PAA‐Cu2+, which were obtained via electrostatic interactions of 2,2′‐diamino‐4,4′‐bithiazole (DABT), poly(acrylic acid) (PAA), and transition metal ions (Cu2+ or Ni2+) were described. FTIR, 1H NMR, and elemental analysis were used to characterize the structures of the obtained supramolecular polymer and the corresponding complexes. The corresponding multilayer films were also constructed on the quartz substrate. UV–vis spectra and AFM images were applied to characterize these films. The result indicates a process of uniform assembling. The magnetic behavior was examined as a function of magnetic field strength at 4 K and as a function of temperature (4–300 K). It was found that DABT/PAA‐Ni2+ exhibits a ferromagnetic property with a high value of relative saturation magnetization, while DABT/PAA‐Cu2+ shows a special magnetic property different from the typical magnet. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Nanostructured membranes based on sulfonated poly(aryl ether sulfone) and silica for fuel‐cell applications
Authors: de Carvalho Luisa Magno , Tan Ai Ren , de Souza Gomes Ailton
Published: July 2008

Nanostructured sulfonated poly(aryl ether sulfone) (SPSU) membranes were made from SPSU/silica composites through the addition of amorphous, precipitated, and micronized silica particles (Tixosil 333) and short or segmented linear structures. Linear and branched segments of silica were obtained from the in situ reaction of tetraethoxysilane (TEOS) in an SPSU solution through a sol–gel acid‐catalyzed process. Different amounts of silica in the SPSU composites were prepared to evaluate their influence on the ionic conductivity, the water and alcohol solution sorption capacities, and the stability in an ethanol medium. The effect of silica (Tixosil) on the conductivity was higher than that of the silica made from TEOS in SPSU composites. The conductivities of the membranes containing 10% Tixosil and 6.6% silica prepared from TEOS were measured at 80°C; their values were 60 and 33 mS/cm, respectively. Furthermore, a membrane made of a silica blend (5% Tixosil and 3% TEOS) in SPSU attained a value of 92 mS/cm, whereas the commercial membrane Nafion 117, used as a reference, had a conductivity of 54 mS/cm measured under the same conditions. All those composites membranes could be used as components in hydrogen fuel cell. However, only the SPSU/2% Tixosil composite could be used in both hydrogen and ethanol direct fuel cells. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Antibacterial effects of a new dental acrylic resin containing silver nanoparticles
Authors: Kassaee M. Z. , Akhavan A. , Sheikh N. , Sodagar A.
Published: July 2008

The addition of silver nanoparticles (Ag NPs) to an acrylic resin rendered a dental composite that exhibited strong antibacterial activity against Escherichia coli and showed rather improved mechanical properties. Such antibacterial effects were mainly attributed to the release of silver ions upon immersion of the composite in water, which appeared to be fairly nontoxic to humans. Furthermore, an acrylic liquid was used as a new reducing agent for the conversion of silver ions into pure elemental Ag NPs in quantitative yields. The structure, morphology, average size, and size distribution of the as‐prepared Ag NPs were determined by scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction, which confirmed the fabrication of rather dispersed, face‐centered cubic nanoparticles with a mean average diameter of 38 nm. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Internet information and communication behavior during a political moment: The Iraq war, March 2003
Authors: Robbin Alice , Buente Wayne
Published: July 2008

This article explores the Internet as a resource for political information and communication in March 2003, when American troops were first sent to Iraq, offering us a unique setting of political context, information use, and technology. Employing a national survey conducted by the Pew Internet & American Life project, we examine the political information behavior of the Internet respondents through an exploratory factor analysis; analyze the effects of personal demographic attributes and political attitudes, traditional and new media use, and technology on online behavior through multiple regression analysis; and assess the online political information and communication behavior of supporters and dissenters of the Iraq War. The factor analysis suggests four factors: activism, support, information seeking, and communication. The regression analysis indicates that gender, political attitudes and beliefs, motivation, traditional media consumption, perceptions of bias in the media, and computer experience and use predict online political information behavior, although the effects of these variables differ for the four factors. The information and communication behavior of supporters and dissenters of the Iraq War differed significantly. We conclude with a brief discussion of the value of “interdisciplinary poaching” for advancing the study of Internet information practices.
Hydrogen photoproduction by nutrient‐deprived Chlamydomonas reinhardtii cells immobilized within thin alginate films under aerobic and anaerobic conditions
Authors: Kosourov Sergey N. , Seibert Michael
Published: July 2008

A new technique for immobilizing H2‐photoproducing green algae within a thin (<400 µm) alginate film has been developed. Alginate films with entrapped sulfur/phosphorus‐deprived Chlamydomonas reinhardtii, strain cc124, cells demonstrate (a) higher cell density (up to 2,000 µg Chl mL−1 of matrix), (b) kinetics of H2 photoproduction similar to sulfur‐deprived suspension cultures, (c) higher specific rates (up to 12.5 µmol mg−1 Chl h−1) of H2 evolution, (d) light conversion efficiencies to H2 of over 1% and (e) unexpectedly high resistance of the H2‐photoproducing system to inactivation by atmospheric O2. The algal cells, entrapped in alginate and then placed in vials containing 21% O2 in the headspace, evolved up to 67% of the H2 gas produced under anaerobic conditions. The results indicate that the lower susceptibility of the immobilized algal H2‐producing system to inactivation by O2 depends on two factors: (a) the presence of acetate in the medium, which supports higher rates of respiration and (b) the capability of the alginate polymer itself to effectively separate the entrapped cells from O2 in the liquid and headspace and restrict O2 diffusion into the matrix. The strategy presented for immobilizing algal cells within thin polymeric matrices shows the potential for scale‐up and possible future applications. Biotechnol. Bioeng. 2008. Biotechnol. Bioeng. 2009;102: 50–58. © 2008 Wiley Periodicals, Inc.
Ionothermal Synthesis of Crystalline, Condensed, Graphitic Carbon Nitride
Authors: Bojdys Michael J. , Müller Jens‐Oliver , Antonietti Markus , Thomas Arne
Published: July 2008

Herein we report the synthesis of a crystalline graphitic carbon nitride, or g‐C3N4, obtained from the temperature‐induced condensation of dicyandiamide (NH2C(NH)NHCN) by using a salt melt of lithium chloride and potassium chloride as the solvent. The proposed crystal structure of this g‐C3N4 species is based on sheets of hexagonally arranged s‐heptazine (C6N7) units that are held together by covalent bonds between C and N atoms which are stacked in a graphitic, staggered fashion, as corroborated by powder X‐ray diffractometry and high‐resolution transmission electron microscopy.
Seismic performance of a 3D full‐scale high‐ductility steel–concrete composite moment‐resisting structure—Part I: Design and testing procedure
Authors: Braconi A. , Bursi O. S. , Fabbrocino G. , Salvatore W. , Tremblay R.
Published: July 2008

A multi‐level pseudo‐dynamic (PSD) seismic test programme was performed on a full‐scale three‐bay two‐storey steel–concrete composite moment‐resisting frame built with partially encased composite columns and partial‐strength connections. The system was designed to provide strength and ductility for earthquake resistance with energy dissipation located in ductile components of beam‐to‐column joints including flexural yielding of beam end‐plates and shear yielding of the column web panel zone. In addition, the response of the frame depending on the column base yielding was analysed. Firstly, the design of the test structure is presented in the paper, with particular emphasis on the ductile detailing of beam‐to‐column joints. Details of the construction of the test structure and the test set‐up are also given. The paper then provides a description of the non‐linear static and dynamic analytical studies that were carried out to preliminary assess the seismic performance of the test structure and establish a comprehensive multi‐level PSD seismic test programme. The resulting test protocol included the application of a spectrum‐compatible earthquake ground motion scaled to four different peak ground acceleration levels to reproduce an elastic response as well as serviceability, ultimate, and collapse limit state conditions, respectively. Severe damage to the building was finally induced by a cyclic test with stepwise increasing displacement amplitudes. Copyright © 2008 John Wiley & Sons, Ltd.
Real‐time quantitative PCR analysis of pediatric ependymomas identifies novel candidate genes including TPR at 1q25 and CHIBBY at 22q12‐q13
Authors: Karakoula Katherine , Suarez‐Merino Blanca , Ward Samantha , Phipps Kim P. , Harkness William , Hayward Richard , Thompson Dominic , Jacques Thomas S. , Harding Brian , Beck John , Thomas David G. T. , Warr Tracy J.
Published: July 2008

Loss of chromosome 22 and gain of 1q are the most frequent genomic aberrations in ependymomas, indicating that genes mapping to these regions are critical in their pathogenesis. Using real‐time quantitative PCR, we measured relative copy numbers of 10 genes mapping to 22q12.3‐q13.33 and 10 genes at 1q21‐32 in a series of 47 pediatric intracranial ependymomas. Loss of one or more of the genes on 22 was detected in 81% of cases, with RAC2 and C22ORF2 at 22q12‐q13.1 being deleted most frequently in 38% and 32% of ependymoma samples, respectively. Combined analysis of quantitative‐PCR with methylation‐specific PCR and bisulphite sequencing revealed a high rate (>60% ependymoma) of transcriptional inactivation of C22ORF2, indicating its potential importance in the development of pediatric ependymomas. Increase of relative copy numbers of at least one gene on 1q were detected in 61% of cases, with TPR at 1q25 displaying relative copy number gains in 38% of cases. Patient age was identified as a significant adverse prognostic factor, as a significantly shorter overall survival time (P = 0.0056) was observed in patients <2 years of age compared with patients who were >2 years of age. Loss of RAC2 at 22q13 or amplification of TPR at 1q25 was significantly associated with shorter overall survival in these younger patients (P = 0.0492 and P = < 0.0001, respectively). This study identifies candidate target genes within 1q and 22q that are potentially important in the pathogenesis of intracranial pediatric ependymomas. © 2008 Wiley‐Liss, Inc.
A pilot study to assess attitudes, behaviors, and inter‐office communication by psychiatrists and primary care providers in the care of older adults with schizophrenia
Authors: Jones Sarah M. , Vahia Ipsit V. , Cohen Carl I. , Hindi Amjad , Nurhussein Mohammed
Published: July 2008

Introduction

There is a lack of assessment tools and empirical data concerning clinician attitudes and behaviors with respect to the health care of older adults with schizophrenia. We develop a survey instrument of physician attitudes, behavior, and inter‐office communication, and provide preliminary data on physician‐related issues in the provision of health care to this population.

Methods

A semi‐structured 20‐item survey instrument was administered to a stratified convenience sample of 24 primary care physicians (PCPs) and 27 psychiatrists working in the New York metropolitan area. Using open ended and multiple choice items, scales, summed scores, and case vignettes, we assessed attitudes, experiences, and procedures in treating medical illnesses in older persons with schizophrenia. All scales had internal consistency reliabilities of >0.70.

Results

There were no differences between PCPs and psychiatrists in reported and anticipated behavior towards older adults with symptoms of schizophrenia, and both groups displayed favorable views. However, both groups had slightly negative stereotypes and attitudes concerning these patients. PCPs reported receiving information from psychiatrists slightly more than 0 to 10 percent of the time.

Conclusions

Our preliminary findings indicated more favorable attitudes and behaviors by PCPs than had been anticipated based on earlier research with younger patients. The data suggest that the failure of older schizophrenia patients to receive adequate treatment may not be due primarily to clinicians' negative attitudes and behaviors, and that problems with communication may play a more important role. Copyright © 2008 John Wiley & Sons, Ltd.
Quiescent epithelial cell rests of Malassez can differentiate into ameloblast‐like cells
Authors: Shinmura Yuka , Tsuchiya Shuhei , Hata Ken‐ichiro , Honda Masaki J.
Published: July 2008

Epithelial cell rests of Malassez (ERM) are quiescent epithelial remnants of Hertwig's epithelial root sheath (HERS) that are involved in the formation of tooth roots. After completion of crown formation, HERS are converted from cervical loop cells, which have the potential to generate enamel for tooth crown formation. Cervical loop cells have the potential to differentiate into ameloblasts. Generally, no new ameloblasts can be generated from HERS, however this study demonstrated that subcultured ERM can differentiate into ameloblast‐like cells and generate enamel‐like tissues in combination with dental pulp cells at the crown formation stage. Porcine ERM were obtained from periodontal ligament tissue by explant culture and were subcultured with non‐serum medium. Thereafter, subcultured ERM were expanded on 3T3‐J2 feeder cell layers until the tenth passage. The in vitro mRNA expression pattern of the subcultured ERM after four passages was found to be different from that of enamel organ epithelial cells and oral gingival epithelial cells after the fourth passage using the same expansion technique. When subcultured ERM were combined with subcultured dental pulp cells, ERM expressed cytokeratin14 and amelogenin proteins in vitro. In addition, subcultured ERM combined with primary dental pulp cells seeded onto scaffolds showed enamel‐like tissues at 8 weeks post‐transplantation. Moreover, positive staining for amelogenin was observed in the enamel‐like tissues, indicating the presence of well‐developed ameloblasts in the implants. These results suggest that ERM can differentiate into ameloblast‐like cells. J. Cell. Physiol. 217: 728–738, 2008. © 2008 Wiley‐Liss, Inc.
Clickable Poly(2‐Oxazoline)s as Versatile Building Blocks
Authors: Fijten Martin W. M. , Haensch Claudia , van Lankvelt Bart M. , Hoogenboom Richard , Schubert Ulrich S.
Published: July 2008

Cationic ring‐opening polymerization techniques are very sensitive to nucleophiles, which make it difficult to introduce different functional groups into these polymers. Clickable poly(2‐oxazoline)s were synthesized and functionalization was performed by the copper(I)‐catalyzed 1,3‐dipolar cycloaddition between alkynes and azides. Therefore, an alkyne function is introduced into the polymer backbone by utilizing alkyne toluene‐4‐sulfonates as an initiator. The polymerization kinetics were investigated for four different 2‐substituted‐2‐oxazolines and well‐defined acetylene‐functionalized poly(2‐ethyl‐2‐oxazoline)s with different lengths were synthesized having ≈100% functionality. One of these polymers was used to demonstrate its applicability in the azide‐alkyne click reaction by reaction with different azide compounds.

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Influence of clay type on exfoliation, cure and physical properties of in situ polymerised poly(methyl methacrylate) nanocomposites
Authors: Ingram Sharon , Dennis Hugh , Hunter Ian , Liggat John J , McAdam Craig , Pethrick Richard A , Schaschke Carl , Thomson David
Published: July 2008

BACKGROUND: The nature of the dispersion of clay platelets in a resin composite will play an important role in the process of enhancement of the physical properties of that material. This paper examines how different modifiers and the quantity of surface treatment for the Cloisite® range of organically modified clays affect properties in in situ polymerised poly(methyl methacrylate). Another clay which is a mixture of rod‐ and platelet‐like minerals is also investigated to understand how the shape of the clay particles can affect the polymer properties.

RESULTS: Five different clays, including Cloisite 30B and Cloisite 15A, were dispersed using ultrasound and the cure of the samples was monitored using the Strathclyde Rheometer. Rheology, transmission electron microscopy and X‐ray diffraction were used to determine that a good level of clay dispersion was achieved. The mixed mineral formed the most stable dispersion seen from settling tests.

CONCLUSIONS: The cure accelerated in the presence of organoclay, although the affect was less pronounced at higher temperatures. The glass transition temperature was increased by 20 °C with only a few weight percent of clay and water uptake was not adversely affected. Copyright © 2008 Society of Chemical Industry
Photopatternable substrate‐independent poly(glycidyl methacrylate‐ran‐2‐(acryloyloxy) ethyl 2‐methylacrylate) polymer films for immobilization of biomolecules
Authors: Cullen Sean P. , Ha Sangkeun , Lagally Max G. , Gopalan Padma
Published: July 2008

We report the synthesis and characterization of a photocrosslinkable copolymer containing reactive epoxy groups for binding biomolecules. The epoxide‐containing copolymer poly(glycidyl methacrylate‐ran‐2‐(acryloyloxy) ethyl 2‐methylacrylate) offers distinct advantages such as ease of application to various substrates, enhanced stability of the bound oligonucleotide, low autofluorescence, and the ability to be photopatterned allowing localization of the linkers. The copolymer uses pendant acryloyl groups to control the crosslinking without sacrificing the epoxide groups. The films were characterized using ellipsometry, atomic force microscopy, and fluorescence microscopy. The films on glass, silicon wafer, and stainless steel showed no appreciable degradation in water, tetrahydrofuran, and acetone for ∼4 months. The surface topography for a given thickness of crosslinked film was dictated by the deposition conditions. A 16mer oligonucleotide was immobilized on the thin films. A linear relationship between the film thickness and amount of oligonucleotide immobilized was observed with a maximum signal‐to‐background ratio (S/B) of 225 for a 60‐nm‐thick film, a value 50% higher than the S/B for an epoxide monolayer. The crosslinked films maintained a high fluorescence signal following long aqueous washing which is appealing for biological microarrays, immobilizing proteins, and study of slow differentiating cells where stability of the scaffold is relevant. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5826–5838, 2008
Synthesis, pH‐ and temperature‐induced micellization and gelation of doubly hydrophilic triblock copolymer of poly(N,N‐dimethylamino‐2‐ethylmethacrylate)‐b‐poly(ethylene glycol)‐b‐poly(N,N‐dimethylamino‐2‐ethylmethacrylate) in aqueous solutions
Authors: Peng Zhiping , Li Guangzhao , Liu Xinxing , Tong Zhen
Published: July 2008

A doubly hydrophilic triblock copolymer of poly(N,N‐dimethylamino‐2‐ethyl methacrylate)‐b‐Poly(ethylene glycol)‐b‐poly(N,N‐dimethylamino‐2‐ethylmethacrylate) (PDMAEMA‐b‐PEG‐b‐PDMAEMA) with well‐defined structure and narrow molecular weight distribution (Mw/Mn = 1.21) was synthesized in aqueous medium via atom transfer radical polymerization (ATRP) of N,N‐dimethylamino‐2‐ethylmethacrylate (DMAEMA) initiated by the PEG macroinitiator. The macroinitiator and triblock copolymer were characterized with 1H NMR and gel permeation chromatography (GPC). Fluorescence spectroscopy, dynamic light scattering (DSL), transmittance measurement, and rheological characterization were applied to investigate pH‐ and temperature‐induced micellization in the dilute solution of 1 mg/mL when pH > 13 and gelation in the concentrated solution of 25 wt % at pH = 14 and temperatures beyond 80 °C. The unimer of Rh = 3.7 ± 0.8 nm coexisted with micelle of Rh = 45.6 ± 6.5 nm at pH 14. Phase separation occurred in dilute aqueous solution of the triblock copolymer of 1 mg/mL at about 50 °C. Large aggregates with Rh = 300–450 nm were formed after phase separation, which became even larger as Rh = 750–1000 nm with increasing temperature. The gelation temperature determined by rheology measurement was about 80 °C at pH 14 for the 25 wt % aqueous solution of the triblock copolymer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5869–5878, 2008
Synthesis, morphology, and properties of hydroxyl terminated‐POSS/polyimide low‐k nanocomposite films
Authors: Wahab Md Abdul , Mya Khine Yi , He Chaobin
Published: July 2008

Polyhedral oligomeric silsequioxane (POSS), having eight hydroxyl groups for the preparation of nanocomposites with polyimide (PI) was synthesized by the direct hydrosilylation of allyl alcohol with octasilsesquioxane (Q8M8H) with platinum divinyltetramethyl disiloxane Pt(dvs) as a catalyst. The structure of allyl alcohol terminated‐POSS (POSS‐OH) was confirmed by FTIR, NMR, and XRD. A high performance, low‐k PI nanocomposite from pyromellitic dianhydride (PMDA)‐4,4'‐oxydianiline (ODA) polyamic acid cured with POSS‐OH was also successfully synthesized. The incorporation of POSS‐OH into PI matrix reduced dielectric constant of PI without loosing mechanical properties. Furthermore, the effects of POSS‐OH on the morphology and properties of the PI/POSS‐OH nanocomposites were investigated using UV–vis, FTIR, XRD, SEM, AFM, transmission electron microscope (TEM), TGA, and contact angle. The homogeneous dispersion of POSS particles was confirmed by SEM, AFM, and TEM. The nanoindentation showed that the modulus increased upon increasing the concentration of POSS‐OH in PI, whereas the hardness did not increase very much with respect to loading of POSS, due to soft‐interphase around POSS molecules in the resulting nanocomposites. Overall results demonstrated the nanometer‐level integration of the polymer and POSS‐OH. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5887–5896, 2008
Disruption of arginase II alters prostate tumor formation in TRAMP mice
Authors: Mumenthaler Shannon M. , Rozengurt Nora , Livesay Justin C. , Sabaghian Anahita , Cederbaum Stephen D. , Grody Wayne W.
Published: July 2008

BACKGROUND

Arginase II (AII) is involved in the polyamine synthetic pathway, and elevated levels of expression have been found in a high proportion of prostate cancer samples and patients. However, the biological function of arginase II in prostate cancer still remains to be elucidated. In this study, we utilized the TRAMP mouse prostate cancer model to better understand the contribution of AII on tumor development.

METHODS

AII expression was determined in prostates from TRAMP mice at 23 weeks of age by real‐time RT‐PCR and Western blot analysis. Additionally, AII expression was disrupted in the TRAMP model by crossbreeding arginase II knockout (AII KO) mice with TRAMP mice in order to generate the TRAMP/AII KO line. In each group, genito‐urinary (GU) tract weights were determined and a pathological evaluation of the tumors was completed.

RESULTS

AII expression was only detectable in those mice without the presence of macroscopic tumors; it was also absent in the TRAMP‐C2 cell line, which is characteristic of an advanced prostate tumor. Assessment of the GU weights revealed larger average GU weights in the TRAMP/AII KO mice compared to TRAMP mice. Additionally, a greater percentage of more advanced pathology was found in the TRAMP/AII KO group compared to the TRAMP cohort.

CONCLUSIONS

Based on these results, AII deficiency in the TRAMP model seems to accelerate prostate tumor progression, leading to an overall more advanced cancer stage in these mice. These findings support the possibility that prostatic arginase II could be a potentially useful marker of disease progression. Prostate 68: 1561–1569, 2008. © 2008 Wiley‐Liss, Inc.
Intracellular death platform steps‐in: Targeting prostate tumors via endoplasmic reticulum (ER) apoptosis
Authors: Schwarze Steven R. , Lin Eric W. , Christian Perry A. , Gayheart Dustin T. , Kyprianou Natasha
Published: July 2008

Molecular targeting of apoptotic signaling pathways has been extensively studied in recent years and directed towards the development of effective therapeutic modalities for treating advanced androgen‐independent prostate tumors. The majority of therapeutic agents act through intrinsic or mitochondrial pathways to induce programmed cell death. The induction of apoptosis through endoplasmic reticulum (ER) stress pathways may provide an alternative to treat patients. The functional interaction between the BCL‐2 family members and regulation of calcium homeostasis in the ER provides a critical link to the life or death outcome of the cell. Apoptosis induction mediated by ER stress‐inducing agents is just beginning to be exploited for therapeutic targeting of prostate tumors. Insightful dissection of recently discovered apoptotic signaling pathways that function through the endoplasmic reticulum may identify novel molecules that could effectively target both androgen‐dependent and androgen‐independent prostate tumors. In this review, we focus on linking ER stress‐induced apoptosis to therapeutic targeting of prostate tumors and dissect its cross‐talk with the intrinsic and extrinsic apoptotic pathways. Prostate 68: 1615–1623, 2008. © 2008 Wiley‐Liss, Inc.
Femtosecond Dynamics in Single Wall Carbon Nanotube/Poly(3-Hexylthiophene) Composites
Authors: Lioudakis Emmanouil , Othonos Andreas , Alexandrou Ioannis
Published: July 2008

Femtosecond transient absorption measurements on single wall carbon nanotube/poly(3-hexylthiophene) composites are used to investigate the relaxation dynamics of this blended material. The influence of the addition of nanotubes in polymer matrix on the ultrashort relaxation dynamics is examined in detail. The introduction of nanotube/polymer heterojunctions enhances the exciton dissociation and quenches the radiative recombination of composites. The relaxation dynamics of these composites are compared with the fullerene derivative-polymer composites with the same matrix. These results provide explanation to the observed photovoltaic performance of two types of composites.
Liouville results for $m$-Laplace equations of Lane–Emden–Fowler type
Authors: Sciunzi Berardino , Damascelli Lucio , Farina Alberto , Valdinoci Enrico
Published: July 2008

We consider sign changing solutions of the equation

−\mathrm{\Delta }_{m}(u) = |u|^{p−1}u

in possibly unbounded domains or in

\mathbb{R}^{N}

. We prove Liouville type theorems for stable solutions or for solutions which are stable outside a compact set. The results hold true for

m > 2

and

m−1 < p < p_{c}(N,m)

. Here

p_{c}(N,m)

is a new critical exponent, which is infinity in low dimension and is always larger than the classical critical one.
Multiple critical points of perturbed symmetric strongly indefinite functionals
Authors: Bonheure Denis , Ramos Miguel
Published: July 2008

We prove that the elliptic system

−\mathrm{\Delta }u = |v|^{q−2}v + k(x),\:x \in \Omega ,

−\mathrm{\Delta }v = |u|^{p−2}u + h(x),\:x \in \Omega ,

where
Ω
is a regular bounded domain of

\mathbb{R}^{N}

,

N⩾3

and

h,k \in L^{2}(\Omega )

, admits an unbounded sequence of solutions

(u_{k},v_{k}) \in H_{0}^{1}(\Omega ) \times H_{0}^{1}(\Omega )

, provided

2 < p⩽q

and

\frac{N}{2}(1−\frac{1}{p}−\frac{1}{q}) < \frac{p−1}{p}

. We also prove a generic multiplicity result for exponents in the open region bounded by the lines

p = 2

,

q = 2

and the critical hyperbola.

Nous démontrons que le système elliptique ((1), (2)) où
Ω
est un domaine régulier de

\mathbb{R}^{N}

,

N⩾3

et
h
,

k \in L^{2}(\Omega )

, possède une suite non bornée de solutions

(u_{k},v_{k}) \in H_{0}^{1}(\Omega ) \times H_{0}^{1}(\Omega )

, pour autant que

2 < p⩽q

et

\frac{N}{2}(1−\frac{1}{p}−\frac{1}{q}) < \frac{p−1}{p}

. Nous démontrons également un résultat générique de mulplicité lorsque les exposants se situent dans l'ouvert délimité par les droites

p = 2

,

q = 2

et l'hyperbole critique.
Integrity of the cortical actin ring is required for activation of the PI3K/Akt and p38 MAPK signaling pathways in redifferentiation of chondrocytes on chitosan
Authors: Park Eun Hee , Kang Shin‐Sung , Lee Young‐Sup , Kim Song‐Ja , Jin Eun‐Jung , Tak Eun Nam , Sonn Jong Kyung
Published: July 2008

Cell shape alterations and accompanying cytoskeletal changes have diverse effects on cell function. We have already shown that dedifferentiated chondrocytes have a round cell morphology and undergo redifferentiation when cultured on chitosan membrane. In the present study, we investigate the role of the cytoskeleton in chondrocyte redifferentiation. Chondrocytes obtained from a micromass culture of chick limb bud mesenchymal cells were subcultured four times. Immunofluorescence analysis of F‐actin showed cortical distribution of the actin cytoskeleton upon subculture of dedifferentiated chondrocytes on chitosan membrane. Treatment with cytochalasin D disrupted the cortical actin ring formed during cultivation of chondrocytes on the chitosan membrane, and inhibited chondrocyte redifferentiation. Moreover, cytochalasin D inhibited the phosphorylation of Akt and p38 mitogen activated protein kinase (MAPK), induced during redifferentiation on chitosan membrane. LY294002, an inhibitor of phosphatidylinositol‐3‐OH‐kinase (PI3K), suppressed chondrocyte redifferentiation. These findings suggest that integrity of the actin cytoskeleton is a crucial requirement for PI3K/Akt and p38 MAPK in chondrocyte redifferentiation.
Assessment of fibroblast cells submitted to ultrasonic irradiation
Authors: De Oliveira Rodrigo Franco , Oliveira Deise A.A. Pires , Machado Aline H.A. , da Silva Newton Soares , Magini Márcio , Pacheco‐Soares Cristina
Published: July 2008

Physiotherapists consider ultrasound an indispensable tool, which is commonly employed in clinical practice as a treatment aid for musculoskeletal dysfunctions. The aim of our study has been to analyze fibroblast cell structures following low‐intensity pulsed ultrasonic irradiation. Fibroblast cell cultures irradiated with ultrasound were analyzed through electron microscopy to determine an ideal irradiation beam that preserved cell morphology and integrity. Analysis by fluorescence microscopy and transmission electron microscopy was used to follow morphological changes of the nucleus and cytoskeleton following different ultrasound irradiation intensities. According to the parameters used in the pulsed irradiation of fibroblast cultures, control over the intensity employed is fundamental to the optimal use of therapeutic ultrasound. Cell cultures submitted to low‐intensity pulsed ultrasonic irradiation (0.2–0.6 W/cm2) at 10% (1:9 duty cycle) and 20% (2:8 duty cycle) maintained shape and cellular integrity, with little damage. In the group irradiated with an intensity of 0.8 W/cm2, a loss of adhesion was observed along with an alteration in the morphology of some cells at an intensity of 1.0 W/cm2, which resulted in the presence of cellular fragments and a decrease of adhering cells. In cells irradiated at 2.0 W/cm2, there was a complete loss of adhesion and aggregation of cellular fragments. The present study confirms that biophysical properties of pulsed ultrasound may accelerate proliferation processes in different biological tissues.
Metabolomic profiling of Drosophila using liquid chromatography Fourier transform mass spectrometry
Authors: Kamleh M.A. , Hobani Y. , Dow J.A.T. , Watson D.G.
Published: July 2008

Hydrophilic interaction chromatography (HILIC) interfaced with an Orbitrap Fourier transform mass spectrometer (FT‐MS) was used to carry out metabolomic profiling of the classical Drosophila mutation, rosy (ry). This gene encodes a xanthine oxidase/dehydrogenase. In addition to validating the technology by detecting the same changes in xanthine, hypoxanthine, urate and allantoin that have been reported classically, completely unsuspected changes were detected in each of the tryptophan, arginine, pyrimidine and glycerophospholipid metabolism pathways. The rosy mutation thus ramifies far more widely than previously detected.
Formation of the coronary vasculature: a brief review
Authors: Tomanek Robert J.
Published: July 2008

Myocardial vascularization is initiated after endothelial cell precursors from the region of the liver or septum transversarium migrate to the newly formed epicardium. Blood island-like structures appear and form vascular channels along the epicardium and into the myocardium. Prior to this time myocardial cells receive nutrition directly from the ventricular lumen, a process which is facilitated by the highly trabecular arrangement of the ventricles. A venous system is formed prior to any evidence of arteries or arterioles. The formation of a vascular plexus in the region of the outflow tract is followed by penetration of these microvessels into the wall of the aorta. These ingrowing vessels merge, acquire a muscular coat and form the left and then the right coronary vessels. These events occur during a short period of time, e.g., 2 weeks in humans, 4 days in rats. Maturation of the arterial tree occurs primarily after birth. Our knowledge of the regulation of coronary vascularization during development is very limited. Accordingly, future studies need to focus on the role of growth factors, chemotactic factors, extracellular matrix molecules, and mechanical events.
Ventricular relaxation in the stage 24 chick embryo following changes in volume and blockade of Na+ and Ca2+ channels
Authors: Naheed Z.J. , Lahoti A. , Hughes S.F. , Benson D.W.
Published: July 2008

Objective

Early in cardiac development, regulation of cytosolic Ca2+ has been thought to depend primarily on sarcolemmal Ca2+ transport. We hypothesized that perturbation of cytosolic Ca2+ in the embryonic ventricle would result in a change in ventricular relaxation which could be quantified by a monoexponential model. We reasoned that since it has been difficult to selectively block the Na+-Ca2+ exchanger in vivo, that blockade of Na+ (lidocaine) or Ca2+ (verapamil) channels in the embryonic heart may perturb cytosolic Ca2+ and thereby alter ventricular relaxation.

Methods

All studies were performed in ovo in Hamilton-Hamburger stage 24 chick embryos. Isovolumic relaxation time (mean ± standard deviation, 58 ± 19 ms) was derived from dorsal aortic flow and atrioventricular inflow during 61 cardiac cycles in 4 embryos. Ventricular pressure was digitally recorded from 13 embryos during 188 cycles following intravenous injection of chick Ringer's solution (5 embryos), verapamil (4 embryos) or lidocaine (4 embryos). Ventricular relaxation was characterized by a monoexponential model: P(t) = P∞ + Poe−t/τ where P(t) = pressure at time (t), P∞ = pressure asymptote, Po = pressure at the onset of relaxation and τ = the isovolumic relaxation constant. Non-linear least-squares regression was used to estimate τ and P∞ during isovolumic relaxation at baseline and at 30 s and 60 s post-injection.

Results

Ventricular end-diastolic pressure was increased by all three interventions. Both lidocaine and verapamil prolonged cycle length. Lidocaine prolonged τ while chick Ringer's solution and verapamil did not. No significant change in P∞ was observed.

Conclusions

This study demonstrates that blockade of Na+ channels with lidocaine slows ventricular relaxation presumably by perturbing cytosolic Ca2+ via the Na+-Ca2+ exchange system. Changes following Ca2+ channel blockade with verapamil are less evident in the stage 24 chick embryo. Evaluation of ventricular relaxation may provide a useful way to study developmental aspects of Ca2+ transport.
Early embryonic vascular development
Authors: Scott Baldwin H.
Published: July 2008

Establishment of a functional vascular system is imperative for normal embryonic growth and development. Building on the excellent descriptive studies of endothelial cell position and behavior, it is now possible to begin to define the mechanisms directing endothelial cell differentiation, commitment, migration and organization into a tube. What are the factors that control differentiation of mesoderm into angioblasts and what is needed for these angioblasts to organize into a vascular bed? These processes involve the careful orchestration of a diverse group of molecules including components of the extracellular matrix, cell adhesion receptors, growth factors and their receptors. This review has discussed just a few of the components that have been implicated as potentially important in the establishment of the vascular system. However, our understanding of how vessels form in the embryo is really quite rudimentary. We are just beginning to understand the delicate balance of both angiogenic and angiostatic processes that result in the intricate patterning and diverse function that is characteristic of developing endothelial cells. We have not even discussed important factors such as the role of blood flow and apoptosis in maintaining and remodeling vascular beds within the embryo nor have we addressed the development of endothelial heterogeneity in the mature animal [reviewed in Ref. 98]. There are certain to be new molecules identified as well as the delineation of new roles for known molecules. In addition, advances in genetic manipulation and improvements in both in vitro and in vivo model systems should provide important new insights into this critical process of vascular ontogeny.
Financial Obligations within the family-Aspects of Intergenerational Maintenance and Succession in England and France
Authors: Oldham Mika
Published: July 2008

THE article examines the different roles played by private and public intergenerational support obligations in England and France, assesses their impact on elderly people and their carers and suggests possible ways in which the law might be used to alleviate some of the difficulties.