bluuebunny/crossref_metadata_2025_split huggingface dataset:
On‐line acoustic attenuation spectroscopy of emulsions stabilized by vinyl alcohol–vinyl acetate copolymers: a model system for the suspension polymerization of vinyl chloride
Authors: Boscher Virginie , Helleboid Renaud , Lasuye Thierry , Stasik Bernard , Riess Gérard 
Published: August 2009

AbstractBACKGROUND: Poly[(vinyl alcohol)‐co‐(vinyl acetate)] (PVA) copolymers obtained by partial hydrolysis of poly(vinyl acetate) are currently used as industrial stabilizers in the suspension polymerization of vinyl chloride monomer (VCM). Their molecular characteristics, mainly the average degree of hydrolysis (DH) and average degree of polymerization (DPw), have a major influence on the monomer droplet size and the properties of the final poly(vinyl chloride) resin.RESULTS: The average droplet size and size distribution of chlorobutane/water emulsions, as a model system for VCM/water emulsions, were studied using acoustic attenuation spectroscopy on‐line with an agitated laboratory reactor. The emulsions were stabilized by PVA with DH values between 73 and 88 mol% and DPw values between 450 and 2500. The effects of agitation speed, stirring time and concentration of the PVA copolymers were investigated. An attempt was made to correlate the interfacial tension and the droplet size.CONCLUSION: On‐line acoustic spectroscopy appears to be a suitable technique for the real‐time control of the droplet size of monomer suspensions. The advantages and limitations of the technique are outlined. The validity and the application limits of the commonly cited correlation between the droplet size and the Weber number are established for polymeric surfactant‐stabilized emulsions. Copyright © 2009 Society of Chemical Industry
Preparation and properties of core–shell alginate–carboxymethylchitosan hydrogels
Authors: Abreu Flávia OMS , Bianchini Carla , Kist Tarso BL , Forte Maria Madalena C 
Published: August 2009

AbstractBACKGROUND: Hydrogels of alginate (ALG) with partially carboxymethylated chitosan (CMCHI) have been produced for drug delivery, based on the interactions between the negative groups and an ionic crosslinker. In the present work, CMCHI was used to evaluate the influence of amino groups that are positively charged at pH = 4 and 6 on the ALG–CMCHI core–shell hydrogel preparation. An ANOVA statistics tool was used to evaluate the effect of composition, pH and chitosan chemical nature on the morphology and swelling properties of the hydrogels in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF).RESULTS: The ALG–CMCHI core–shell hydrogels presented smaller (ca 2.3 µm) and more homogeneous microparticles than those with unmodified chitosan (ca 5.5 µm). The ALG–CMCHI hydrogels showed higher thermal stability and lower degree of swelling in SGF (314%) compared to those with chitosan (708%), since in the former hydrogels the protective layers that surround the particles are negatively charged.CONCLUSION: CMCHI can replace chitosan in the production of core–shell hydrogels with improved properties since the negative charge surrounding the ALG–CMCHI particles favours a lower degree of swelling. The results point out a possible prevention of burst release in SGF, sustaining the swelling ability of the ALG–CMCHI core–shell hydrogels in SIF, promising appropriate drug release. Copyright © 2009 Society of Chemical Industry
Synthesis and characterization of novel aromatic polyamides derived from 2,2′‐bis(p‐phenoxyphenyl)‐4, 4′‐diaminodiphenyl ether
Authors: Behniafar Hossein , Khosravi‐borna Saeed 
Published: August 2009

AbstractBACKGROUND: Wholly aromatic polyamides (aramids) are high‐performance polymeric materials with outstanding heat resistance and excellent chemical stabilities due to chain stiffness and intermolecular hydrogen bonding of amide groups. Synthesis of structurally well‐designed monomers is an effective strategy to prepare modified forms of these aramids to overcome lack of organo‐solubility and processability limitations.RESULTS: A novel class of wholly aromatic polyamides was prepared from a new diamine, namely 2,2′‐bis(p‐phenoxyphenyl)‐4,4′‐diaminodiphenyl ether (PPAPE), and two simple aromatic dicarboxylic acids. Two reference polyamides were also prepared by reacting 4,4′‐diaminodiphenyl ether with the same comonomers under similar conditions. M̄w and M̄n of the resultant polymers were 8.0 × 104 and 5.5 × 104 g mol−1, respectively. Polymers resulting from PPAPE exhibited a nearly amorphous nature. These polyamides exhibited excellent organo‐solubility in a variety of polar solvents and possessed glass transition temperatures up to 200 °C. The 10% weight loss temperatures of these polymers were found to be up to 500 °C under a nitrogen atmosphere. The polymers obtained from PPAPE could be cast into transparent and flexible films from N,N‐dimethylacetamide solution.CONCLUSION: The results obtained show that the new PPAPE diamine can be considered as a good monomer to enhance the processability of its resultant aromatic polyamides while maintaining their high thermal stability. The observed characteristics of the polyamides obtained make them promising high‐performance polymeric materials. Copyright © 2009 Society of Chemical Industry
Isospecific polymerization of vinyl ethers with titanium catalysts containing modified tridentate anionic donor ligands
Authors: Sudhakar Padmanabhan , Vijayakrishna Kari 
Published: August 2009

AbstractBACKGROUND: Stereo‐regulated polymerization of vinyl ethers (VEs) assumes significance because of its elegance and the resultant unique polymer properties. Although several Lewis acid catalysts polymerize VEs with good control of molecular weight, achieving stereo‐regularity is quite challenging. There are literature reports of a few catalyst systems capable of producing highly isotactic poly(vinyl ether) (PVE) only at lower temperatures with the polymer becoming atactic with an increase in reaction temperature. Hence innovating new catalyst systems which can produce highly stereo‐regular PVEs with high molecular weight at ambient temperature is quite challenging.RESULTS: We used two different titanium pre‐catalysts (1‐TiCl2 and 2‐TiCl2) for the polymerization of VEs. These pre‐catalysts in combination with methylaluminoxane (MAO)/borate polymerized VEs in higher conversions. Highly isotactic poly(n‐butylvinyl ether) (PBVE; 75% dyad isotactic ratio) was obtained with 1‐TiCl2/MAO at ambient temperature.CONCLUSION: We synthesized unimodal and highly isotactic PBVE with molecular weights of the order of 105 g mol−1 using the non‐metallocene‐type single‐site catalyst system 1‐TiCl2/MAO even at ambient temperature. The symmetry around the metal centre in the pre‐catalyst and the polymerization temperature played a major role in controlling the stereo‐regularization of the olefin inserted. Copyright © 2009 Society of Chemical Industry
Growth of scandium aluminum nitride nanowires on ScN(111) films on 6H‐SiC substrates by HVPE
Authors: Bohnen Tim , van Dreumel Gerbe W. G. , Hageman Paul R. , Algra Rienk E. , van Enckevort Willem J. P. , Vlieg Elias , Verheijen Marcel A. , Edgar James H. 
Published: August 2009

AbstractThe formation of ScAlN nanowires on ScN/6H‐SiC(0001) by hydride vapor phase epitaxy (HVPE) was analyzed. The diameters and lengths of the nanowires were 50 to 150 nm and 1 µm, respectively. The nanowires had a Al/Sc metal ratio of 95/5 as measured by energy dispersive analysis of X‐rays (EDX). The 4.84 Å unit cell periodicity along the length of the ScAlN nanowires was similar to that of pure AlN (4.98 Å), as measured by Fourier transforms of high resolution transmission electron microscopy images of a single nanowire. Only the (111) and (222) peaks of the ScN continuous film and the (0006) of the 6H‐SiC substrate were detected by θ‐2θ X‐ray diffraction. A tentative model, based on catalyst‐induced growth, is proposed to explain the unintentional formation of nanowires on the ScN film. This model is based on the production of volatile Al (possibly AlCl) by the reaction of the scandium metal source with the alumina reactor tube and subsequent reaction with hydrogen chloride. This reacts with ammonia in the deposition zone to create ScAlN nanowires, catalyzed by small ScAl clusters, which are spontaneously formed on the ScN film before the nanowire growth.magnified image
SEM images of the ScAlN nanowires.
Chinese hamster ovary cell viability on hydrogen and oxygen terminated nano‐ and microcrystalline diamond surfaces
Authors: Smisdom Nick , Smets Ilse , Williams Oliver A. , Daenen Michaël , Wenmackers Sylvia , Haenen Ken , Nesládek Miloš , D'Haen Jan , Wagner Patrick , Rigo Jean‐Michel , Ameloot Marcel , vandeVen Martin 
Published: August 2009

AbstractTransfected Chinese hamster ovary cells were cultured on bare uncoated chemical vapor deposited thin nano‐ and microcrystalline diamond surfaces, hydrophobic hydrogen‐ and hydrophilic oxygen‐terminated. Optical and biochemical analyses show that compared to glass controls, growth and viability were not significantly affected (one‐way‐analysis of variance, ANOVA). Based on two‐way ANOVA analyses, neither grain size nor surface termination had a significant influence until 5 days post‐seeding.
Ab initio prediction of half‐metallic ferromagnetic metamaterials composed of alkali metals with nitrogen
Authors: Zberecki Krzysztof , Adamowicz Leszek , Wierzbicki Michał 
Published: August 2009

AbstractThe first‐principles full‐potential linearized augmented plane‐wave method based on density functional theory is used to investigate electronic structure and magnetic properties of IA subgroup elements with nitrogen (LiN, NaN, KN, and RbN) in assumed three types of crystalline structure (rock salt, wurtzite, and zinc‐blende). We find that, due to the spin polarized p orbitals of N, all four compounds are half‐metallic ferromagnets with wide energy bandgaps (up to 2.0 eV). The calculated total magnetic moment in all investigated compounds for all three types of crystal structure is exactly 2.00 µB per formula unit. The predicted half‐metallicity is robust with respect to lattice‐constant contraction. In all the cases ferromagnetic phase is energetically favored with respect to the paramagnetic one. These theoretical results extend the range of materials which are potential candidates for synthesizing new magnetic systems needed in spin electronics.
Mass spectrometric study of N‐glycans from serum of woodchucks with liver cancer
Authors: Lattová Erika , McKenzie Eilean J. , Gruwel Marco L. H. , Spicer Vic , Goldman Radoslav , Perreault Hélène 
Published: August 2009

AbstractWoodchucks have been a preferred lab animal model of chronic hepatitis B viral infection. The model recapitulates the disease progression of HBV infection to hepatocellular carcinoma (HCC) and has documented similarities in protein glycosylation with human HCC. This study examined N‐glycans in serum of animals with(out) HCC. Oligosaccharides were released enzymatically using PNGaseF from total serum or from serum partially fractionated by extraction. Two different extraction procedures – reversed‐phase high‐performance liquid chromatography (RP‐HPLC) and solid‐phase extraction (SPE) on a cation‐exchange/reversed‐phase STRATA‐XC cartridge – were used with the purpose of confirming glycosylation profiles. Oligosaccharides were analyzed by matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) after derivatization with phenylhydrazine and/or permethylation. Characteristic fragment ions produced under MS/MS conditions allowed discrimination between isomeric structures of oligosaccharides, including those sialylated with two types of acidic residues. The complementary methods allowed structural characterization of oligosaccharides from various N‐glycan classes. Furthermore, to validate results, glycosylation profiles of woodchuck sera were compared to glycans obtained from mouse serum on the same conditions. In summary, we have identified 40 N‐glycan structures in the serum of woodchucks and some types of oligosaccharide structures appeared to increase in HCC samples following protease digest. The study provides improved tools for the characterization of N‐glycans from total serum in the progression of liver disease. Copyright © 2009 John Wiley & Sons, Ltd.
Systematic analysis of posttranscriptional gene expression
Authors: Morris Adam R. , Mukherjee Neelanjan , Keene Jack D. 
Published: August 2009

AbstractRecent systems studies of gene expression have begun to dissect the layers of regulation that underlie the eukaryotic transcriptome, the combined consequence of transcriptional and posttranscriptional events. Among the regulatory layers of the transcriptome are those of the ribonome, a highly dynamic environment of ribonucleoproteins in which RNA‐binding proteins (RBPs), noncoding regulatory RNAs (ncRNAs) and messenger RNAs (mRNAs) interact. While multiple mRNAs are coordinated together in groups within the ribonome of a eukaryotic cell, each individual type of mRNA consists of multiple copies, each of which has an opportunity to be a member of more than one modular group termed a posttranscriptional RNA operon or regulon (PTRO). The mRNAs associated with each PTRO encode functionally related proteins and are coordinated at the levels of RNA stability and translation by the actions of the specific RBPs and noncoding regulatory RNAs. This article examines the methods that led to the elucidation of PTROs and the coordinating mechanisms that appear to regulate the RNA components of PTROs. Moreover, the article considers the characteristics of the dynamic systems that drive PTROs and how mRNA components are bound collectively in physical ‘states’ to respond to cellular perturbations and diseases. In conclusion, these studies have challenged the extent to which cellular mRNA abundance can inform investigators of the functional status of a biological system. We argue that understanding the ribonome has greater potential for illuminating the underlying coordination principles of growth, differentiation, and disease. Copyright © 2009 John Wiley & Sons, Inc.This article is categorized under:

Biological Mechanisms > Regulatory Biology
Characterization of chromosomal integration sites for heterologous gene expression in Saccharomyces cerevisiae
Authors: Bai Flagfeldt Dongmei , Siewers Verena , Huang Le , Nielsen Jens 
Published: August 2009

AbstractThe construction of mitotically stable yeast strains for heterologous gene or pathway expression often requires chromosomal integration. However, transcription levels vary between different chromosome regions. We therefore characterized 20 different integration sites of the Sacchromyces cerevisiae genome by inserting lacZ as a reporter gene under the control of two different promoters and determining expression levels through enzyme activity measurement. An up to 8.7‐fold difference was detected between the sites conferring lowest and highest expression, respectively. This opens the opportunity for modulating gene expression levels while retaining promoter and culture conditions. Copyright © 2009 John Wiley & Sons, Ltd.
Organ‐Specific Distributions of Lysophosphatidylcholine and Triacylglycerol in Mouse Embryo
Authors: Hayasaka Takahiro , Goto‐Inoue Naoko , Zaima Nobuhiro , Kimura Yoshishige , Setou Mitsutoshi 
Published: August 2009

AbstractImaging mass spectrometry (IMS) has been developed as a method for determining and visualizing the distribution of proteins and lipids across sections of dissected tissue. Although lipids play an important role in mammal development, their detailed distributions have not been analyzed by conventional methods. In this study, we tried to determine and visualize lysophosphatidylcholine (LysoPtdCho) and triacylglycerol (TAG) in a mouse embryo by matrix‐assisted laser desorption/ionization (MALDI) hybrid quadrupole time‐of‐flight (TOF) mass spectrometer. Many peaks were detected from a raster scan of the whole embryonic sections. The peaks at m/z 496.33, 524.36, 879.72, 881.74, and 921.74 were identified by MS/MS analyses as [LysoPtdCho (16:0) + H]+, [LysoPtdCho (18:0) + H]+, [TAG (16:0/18:2/18:1) + Na]+, [TAG (16:0/18:1/18:1) + Na]+, and [TAG (16:0/20:3/18:1) + K]+, respectively. The ion images constructed from the peaks revealed that LysoPtdCho were distributed throughout the body and TAGs were distributed around the brown adipose tissue and in the liver at embryo day 17.5. Thus, IMS system based on MALDI hybrid quadrupole TOF MS revealed the distribution of LysoPtdCho and, more importantly, the organ‐specific distribution of TAGs in the embryonic stages of mammals for the first time. We can conclude that this technique enables us to analyze the roles of various lipids during embryogenesis and gives insight for lipid research.
Exploring older women's citizenship: understanding the impact of migration in later life
Authors: COOK JOANNE 
Published: August 2009

ABSTRACTResearch on the ways in which having been an international migrant in later life shapes the welfare needs, preferences and expectations of non-native older people in rich countries is in its infancy, for both the ageing and migration fields have been slow to examine the experiences of older migrants. This paper focuses upon the welfare citizenship experiences of older women who migrated in later life to England, either as refugees or as post-retirement migrants. It reports findings from interviews and focus groups conducted with black Caribbean, Irish, Chinese and Somali older women migrants in Sheffield, Yorkshire, UK, as part of the Older Women's Lives and Voices Study. The paper explores their experiences of accessing welfare citizenship and the barriers they encountered in accessing mainstream services. In particular, it examines the unequal platform from which older migrants who do not speak English access welfare citizenship rights and services, and assesses the important constraints of discrimination and language differences. Despite the obstacles, the older women participants were actively pursuing their inclusion in welfare rights and services. The paper argues for more recognition of the important enabling role that informal systems of support provided by participation in community or cultural organisations plays in the welfare citizenship and agency of minority ethnic older women.
Selection criteria for flagship species by conservation organizations
Authors: HOME ROBERT , KELLER CLAUDIA , NAGEL PETER , BAUER NICOLE , HUNZIKER MARCEL 
Published: August 2009

SUMMARYFlagship species are among key marketing tools used by conservation organizations to motivate public support, but are often selected in an ad hoc, rather than systematic, manner. Furthermore, it is unclear whether selected flagship species do motivate public support. This paper describes a multi-method exploratory study, carried out in Switzerland, which aimed to determine the selection criteria for flagship species and measure whether a species selected according to these criteria was able to motivate support. Fourteen representatives of international, regional and local conservation organizations were interviewed and the selection criteria for their flagship species were identified. A charismatic species (the great spotted woodpecker) that meets these criteria and an apparently less charismatic species (the clover stem weevil) were selected as treatments in a quantitative experiment with 900 respondents. Using conjoint analysis, it was found that both charismatic and uncharismatic species have the ability to positively influence public preferences for habitat variables that encourage biodiversity in urban landscapes. These results may be used by conservation organizations to assist in the selection of flagship species, and in particular for flagship species that are intended to perform a specific conservation function.
Measles outbreak linked to a minority group in Austria, 2008
Authors: SCHMID D. , HOLZMANN H. , SCHWARZ K. , KASPER S. , KUO H-W. , ABERLE S. W. , REDLBERGER-FRITZ M. , HAUTMANN W. , SANTIBANEZ S. , MANKERTZ A. , KÖNIG C. , MAGNET E. , REICHART S. , MEUSBURGER S. , LUCKNER-HORNISCHER A. , DE MARTIN A. , BECHTER E. , STIRLING J. , ALLERBERGER F. 
Published: August 2009

SUMMARYWe report on a measles outbreak originating in an anthroposophic community in Austria, 2008. A total of 394 (94·9%) cases fulfilled the outbreak case definition including 168 cases affiliated to the anthroposophic community. The source case was a school pupil from Switzerland. The Austrian outbreak strain was genotype D5, indistinguishable from the Swiss outbreak strain. A school-based retrospective cohort study in the anthroposophic school demonstrated a vaccine effectiveness of 97·3% in pupils who had received a single dose of measles-containing vaccine and 100% in those who had received two doses. The vaccination coverage of the cases in the anthroposophic community was 0·6%. Of the 226 outbreak cases not belonging to the anthroposophic community, the 10–24 years age group was the most affected. Our findings underline the epidemiological significance of suboptimal vaccination coverage in anthroposophic communities and in older age groups of the general population in facilitating measles virus circulation. The findings of this outbreak investigation suggest that the WHO European Region is unlikely to achieve its 2010 target for measles and rubella elimination.
Pharmacological characterization, localization, and regulation of ionotropic glutamate receptors in skate horizontal cells
Authors: KREITZER MATTHEW A. , BIRNBAUM ANDREA D. , QIAN HAOHUA , MALCHOW ROBERT PAUL 
Published: August 2009

AbstractGlutamate is believed to be the primary excitatory neurotransmitter in the vertebrate retina, and its fast postsynaptic effects are elicited by activating NMDA-, kainate-, or AMPA-type glutamate receptors. We have characterized the ionotropic glutamate receptors present on retinal horizontal cells of the skate, which possess a unique all-rod retina simplifying synaptic circuitry within the outer plexiform layer (OPL). Isolated external horizontal cells were examined using whole-cell voltage-clamp techniques. Glutamate and its analogues kainate and AMPA, but not NMDA, elicited dose-dependent currents. The AMPA receptor antagonist GYKI 52466 at 100μmabolished glutamate-elicited currents. Desensitization of glutamate currents was removed upon coapplication of cyclothiazide, known to potentiate AMPA receptor responses, but not by concanavalin A, which potentiates kainate receptor responses. The dose–response curve to glutamate was significantly broader in the presence of the desensitization inhibitor cyclothiazide. Polyclonal antibodies directed against AMPA receptor subunits revealed prominent labeling of isolated external horizontal cells with the GluR2/3 and GluR4 antibodies. 1-Naphthylacetyl spermine, known to block calcium-permeable AMPA receptors, significantly reduced glutamate-gated currents of horizontal cells. Downregulation of glutamate responses was induced by increasing extracellular ion concentrations of Zn2+and H+. The present study suggests that Ca2+-permeable AMPA receptors likely play an important role in shaping the synaptic responses of skate horizontal cells and that alterations in extracellular concentrations of calcium, zinc, and hydrogen ions have the potential to regulate the strength of postsynaptic signals mediated by AMPA receptors within the OPL.