bluuebunny/crossref_metadata_2025 huggingface dataset:
Tracking changes in Z‐band organization during myofibrillogenesis with FRET imaging
Authors: Stout Andrea L. , Wang Jushuo , Sanger Jean M. , Sanger Joseph W.
Published: March 2008

There are a large number of proteins associated with Z‐bands in myofibrils, but the precise arrangements of most of these proteins in Z‐bands are largely unknown. Even less is known about how these arrangements change during myofibrillogenesis. We have begun to address this issue using Sensitized Emission Fluorescence Resonance Energy Transfer (SE‐FRET) microscopy. Cultured skeletal muscle cells from quail embryos were transfected to express fusions of alpha‐actinin, FATZ, myotilin, or telethonin with cyan and yellow fluorescent proteins in various pair wise combinations. FATZ and myotilin were selected because previous biochemical studies have suggested that they bind to alpha‐actinin, the major protein of the Z‐band. Telethonin was selected for its reported ability to bind FATZ. Statistical analysis of data from FRET imaging studies yield results that are in agreement with published biochemical data suggesting that FATZ and myotilin bind to alpha‐actinin near its C‐terminus as well as to each other and that a region near the amino‐terminus of FATZ is responsible for its interaction with telethonin. In addition, our analysis has revealed changes in the arrangement of alpha‐actinin and FATZ that take place during the transition as the z‐bodies of premyofibrils fuse to form the Z‐bands of mature myofibrils. There was no evidence for a change in the arrangement of myotilin as z‐bodies transformed into Z‐bands. Myotilin is one Z‐band protein that does not exhibit decreased dynamics as z‐bodies fuse to form Z‐bands. These FRET results from living cells support a stepwise model for the assembly of myofibrils. Cell Motil. Cytoskeleton 2008. © 2008 Wiley‐Liss, Inc.
Myosin Va phosphorylated on Ser1650 is found in nuclear speckles and redistributes to nucleoli upon inhibition of transcription
Authors: Pranchevicius Maria Cristina S. , Baqui Munira M. A. , Ishikawa‐Ankerhold Hellen C. , Lourenço Elaine V. , Leão Ricardo M. , Banzi Silmara R. , dos Santos Claudia Tavares , Barreira Maria Cristina R. , Espreafico Enilza M. , Larson Roy E.
Published: March 2008

Nuclear actin and nuclear myosins have been implicated in the regulation of gene expression in vertebrate cells. Myosin V is a class of actin‐based motor proteins involved in cytoplasmic vesicle transport and anchorage, spindle‐pole alignment and mRNA translocation. In this study, myosin‐Va, phosphorylated on a conserved serine in the tail domain (phospho‐ser1650 MVa), was localized to subnuclear compartments. A monoclonal antibody, 9E6, raised against a peptide corresponding to phosphoserine1650 and flanking regions of the murine myosin Va sequence, was immunoreactive to myosin Va heavy chain in cellular and nuclear extracts of HeLa cells, PC12 cells and B16‐F10 melanocytes. Immunofluorescence microscopy with this antibody revealed discrete irregular spots within the nucleoplasm that colocalized with SC35, a splicing factor that earmarks nuclear speckles. Phospho‐ser1650 MVa was not detected in other nuclear compartments, such as condensed chromatin, Cajal bodies, gems and perinucleolar caps. Although nucleoli also were not labeled by 9E6 under normal conditions, inhibition of transcription in HeLa cells by actinomycin D caused the redistribution of phospho‐ser1650 MVa to nucleoli, as well as separating a fraction of phospho‐ser1650 MVa from SC35 into near‐neighboring particles. These observations indicate a novel role for myosin Va in nuclear compartmentalization and offer a new lead towards the understanding of actomyosin‐based gene regulation. Cell Motil. Cytoskeleton 2008. © 2008 Wiley‐Liss, Inc.
Sulfonation of Phenols Extracted from the Pyrolysis Oil of Oil Palm Shells for Enhanced Oil Recovery
Authors: Awang Mariyamni , Seng Goh Meng
Published: March 2008

The cost of chemicals prohibits many technically feasible enhanced oil recovery methods to be applied in oil fields. It is shown that by‐products from oil palm processing can be a source of valuable chemicals. Analysis of the pyrolysis oil from oil palm shells, a by‐product of the palm oil industry, reveals a complex mixture of mainly phenolic compounds, carboxylic acids, and aldehydes. The phenolic compounds were extracted from the pyrolysis oil by liquid–liquid extraction using alkali and an organic solvent and analyzed, indicating the presence of over 93 % phenols and phenolic compounds. Simultaneous sulfonation and alkylation of the pyrolysis oil was carried out to produce surfactants for application in oil fields. The lowest measured surface tension and critical micelle concentration was 30.2 mN m−1 and 0.22 wt %, respectively. Displacement tests showed that 7–14 % of the original oil in place was recovered by using a combination of surfactants and xanthan (polymer) as additives.
Hydrido Complexes of Yttrium and Lutetium Supported by Bulky Guanidinato Ligands [Ln(μ‐H){(Me3Si)2NC(NCy)2}2]2 (Ln = Y, Lu): Synthesis, Structure, and Reactivity
Authors: Lyubov Dmitrii M. , Bubnov Alexey M. , Fukin Georgy K. , Dolgushin Fedor M. , Antipin Mikhail Yu. , Pelcé Olivier , Schappacher Michèle , Guillaume Sophie M. , Trifonov Alexander A.
Published: March 2008

Lewis base free hydrido complexes of yttrium and lutetium supported by bulky cyclohexyl‐substituted guanidinato ligands, [Ln(μ‐H){(Me3Si)2NC(NCy)2}2]2 (Ln = Y, Lu), were synthesized and characterized. Single‐crystal X‐ray diffraction studies revealed dimeric structures. 1H NMR spectroscopy shows that complex [Y(μ‐H){(Me3Si)2NC(NCy)2}2]2 retains its dimeric structure in C6D6 solution. Scrambling of the hydrido complexes [Ln(μ‐H){(Me3Si)2NC(NCy)2}2]2 (Ln = Y, Lu) in C6D6 resulted in an equilibrium mixture containing the heterodimetallic species [{(Me3Si)2NC(NCy)2}2Y(μ‐H)2Lu{(Me3Si)2NC(NCy)2}2], indicating the dissociation of dimers and the presence of monomeric species in solution. Both compounds initiate the polymerization of ethylene: the activity of the cyclohexyl‐substituted yttrium complex, [Y(μ‐H){(Me3Si)2NC(NCy)2}2]2, is much lower than that of the isopropyl‐substituted analogue, [Y(μ‐H){(Me3Si)2NC(NiPr)2}2]2, while in the case of lutetium the activities of [Ln(μ‐H){(Me3Si)2NC(NR)2}2]2 (R = iPr, Cy) are similar. Complexes [Ln(μ‐H){(Me3Si)2NC(NR)2}2]2 (Ln = Y, Lu; R = iPr, Cy) were shown to catalyze efficiently the hydrosilylation of 1‐nonene with PhSiH3 (at a 1:1 substrates mol ratio) to give the terminal silane PhSiH2(n‐C9H19) exclusively. If the hydrosilylation reaction is carried out in the presence of a twofold molar excess of 1‐nonene, double addition takes place and leads to the formation of tertiary silane PhSiH(n‐C9H19)2, which was obtained in 96 % yield. The hydrido complexes [Ln(μ‐H){(Me3Si)2NC(NiPr)2}2]2 (Ln = Y, Lu) efficiently initiate the ring‐opening polymerization of ϵ‐caprolactone to give polymers with molar mass up to 80000.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis, Radiolabelling and Confocal Fluorescence Microscopy of Styrene‐Derivatised Bis(thiosemicarbazonato)zinc and ‐copper Complexes
Authors: Holland Jason P. , Barnard Peter J. , Bayly Simon R. , Betts Helen M. , Churchill Grant C. , Dilworth Jonathan R. , Edge Ruth , Green Jennifer C. , Hueting Rebekka
Published: March 2008

The synthesis of zinc(II) and copper(II) complexes of an unsymmetrical bis(thiosemicarbazonato) ligand containing a reactive styrene group are reported. The compounds have been characterised by a range of techniques including reverse‐phase HPLC, cyclic voltammetry, NMR, UV/Vis, electron paramagnetic resonance and fluorescence emission spectroscopy. Time‐dependent density functional theory calculations have been used to assign the electronic absorption spectrum of [ZnIIATSM] and probe the nature of the fluorescent excited state. Electrochemistry experiments show that the copper(II) complex undergoes quasi‐reversible one‐electron reduction at biologically accessible potentials and is within the range proposed for the complex to be hypoxia‐selective. The copper‐64 radiolabelled complex has been prepared in aqueous solution and characterised by reverse‐phase radio‐HPLC. Cellular uptake in HeLa cells has been observed using confocal fluorescence microscopy.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Antioxidant capacity of the striped sunflower seed (Helianthus annuus L.) aqueous extract
Authors: de Lourdes Reis Giada Maria
Published: March 2008

The aim of this work was to study the aqueous extract of cotyledons derived from the striped sunflower seeds, with regard to the kinetics of its antioxidant capacity and its phenolic composition. The results showed that, among the phenolic compounds of this extract which were identified by gas chromatography, chlorogenic acid (12.88%) was the prevailing compound. The effectiveness of the aqueous extract in the β‐carotene/linoleate model system was estimated on the basis of the oxidation induction period, which was determined by the method of tangents to the two parts of this extract's kinetic curve, and the study showed that the extract antioxidants may be effective in blocking radical chain reactions and may also interfere with the reactions that produce the secondary products that speed up the system's oxidative process when present in higher concentrations (233.2 µg/mL). The result found by the Rancimat® method showed that the aqueous extract at 300 µg/mL (15.2% IP) was comparable to the BHA standard at 100 µg/mL (16.0 ± 0.86%) in a lipidic system.
Novel Chiral 1,3‐Diamines by a Highly Modular Umpolung Strategy Employing a Diastereoselective Fluorination–Nucleophilic Aromatic Substitution Sequence
Authors: Braun Wolfgang , Calmuschi‐Cula Beatrice , Englert Ulli , Höfener Karola , Alberico Elisabetta , Salzer Albrecht
Published: March 2008

A new highly modular synthesis for the rare class of chiral 1,3‐diamines has been devised. It is accessible through nucleophilic aromatic ipso‐substitution of fluorine in [(R,R)‐1‐fluoro‐2‐{(1‐dimethylamino)ethyl}benzene]tricarbonylchromium and related complexes by secondary as well as primary amines. The precursor is accessible by a new diastereoselective electrophilic fluorination using N‐fluorobenzenesulfonimide (NFSI), and the method is of potential interest for the synthesis of fluorinated pharmaceuticals. The protocol allows for the straightforward, modular synthesis of a broad library of diamines. A stock of 21 diamines has been synthesized. Primary amines bearing a stereogenic α‐center can be introduced without loss of optical purity, yielding planar‐chiral diamines with two stereogenic centers in close proximity. An extended number of X‐ray structures of these diamines is presented and discussed along with NMR experiments which show them to be “chiral proton‐donors”. The 1,3‐diaminoarene moiety can easily be liberated from the chromium complex by decomplexation with I2 as exemplified in four examples. The new methodology adds a powerful tool to the synthesis of organic diamines, and opens a new way to the formerly difficult‐to‐access class of chiral 1,3‐diamines. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Terpioside from the Marine Sponge Terpios sp., the First Glycosphingolipid Having an L‐Fucofuranose Unit
Authors: Costantino Valeria , Fattorusso Ernesto , Imperatore Concetta , Mangoni Alfonso , Teta Roberta
Published: March 2008

The new diglycosylceramide terpioside (1a) has been isolated from the marine sponge Terpios sp. Terpioside is a diglycosylated glycosphingolipid which is the first example of a natural glycosphingolipid having an L‐fucofuranose unit. The structure of terpioside was elucidated by extensive spectroscopic analysis, whereas chemical degradation was used to establish the nature of the alkyl chains and the absolute configuration of the sugars and of the ceramide stereogenic centers.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Electroanalytical Applications of Microporous Zeolites and Mesoporous (Organo)Silicas: Recent Trends
Authors: Walcarius Alain
Published: March 2008

Microporous zeolites and ordered mesoporous (organo)silicas have been widely used as electrode modifiers because of their attractive properties (ion exchange and size selectivity of zeolites, well ordered nanoreactors containing a high number of widely accessible active centers in mesoporous (organo)silicas). These properties have been intelligently combined to selected redox processes to improve the response of the resulting modified electrodes or to design novel electrochemical detection schemes. This up‐to‐date review provides the recent advances made in the electroanalytical applications of zeolite modified electrodes and discusses the interest of ordered mesoporous (organo)silica materials in electroanalysis.
Measuring and partitioning the high‐order linkage disequilibrium by multiple order Markov chains
Authors: Kim Yunjung , Feng Sheng , Zeng Zhao‐Bang
Published: March 2008

A map of the background levels of disequilibrium between nearby markers can be useful for association mapping studies. In order to assess the background levels of linkage disequilibrium (LD), multilocus LD measures are more advantageous than pairwise LD measures because the combined analysis of pairwise LD measures is not adequate to detect simultaneous allele associations among multiple markers. Various multilocus LD measures based on haplotypes have been proposed. However, most of these measures provide a single index of association among multiple markers and does not reveal the complex patterns and different levels of LD structure. In this paper, we employ non‐homogeneous, multiple order Markov Chain models as a statistical framework to measure and partition the LD among multiple markers into components due to different orders of marker associations. Using a sliding window of multiple markers on phased haplotype data, we compute corresponding likelihoods for different Markov Chain (MC) orders in each window. The log‐likelihood difference between the lowest MC order model (MC0) and the highest MC order model in each window is used as a measure of the total LD or the overall deviation from the gametic equilibrium for the window. Then, we partition the total LD into lower order disequilibria and estimate the effects from two‐, three‐, and higher order disequilibria. The relationship between different orders of LD and the log‐likelihood difference involving two different orders of MC models are explored. By applying our method to the phased haplotype data in the ENCODE regions of the HapMap project, we are able to identify high/low multilocus LD regions. Our results reveal that the most LD in the HapMap data is attributed to the LD between adjacent pairs of markers across the whole region. LD between adjacent pairs of markers appears to be more significant in high multilocus LD regions than in low multilocus LD regions. We also find that as the multilocus total LD increases, the effects of high‐order LD tends to get weaker due to the lack of observed multilocus haplotypes. The overall estimates of first, second, third, and fourth order LD across the ENCODE regions are 64, 23, 9, and 3%. Genet. Epidemiol. 2008. © 2008 Wiley‐Liss, Inc.
Using disease symptoms to improve detection of linkage under genetic heterogeneity
Authors: Bureau Alexandre , Labbe Aurélie , Croteau, Jordie , Mérette Chantal
Published: March 2008

A major reason for the slow progress in identifying susceptibility genes for complex diseases may be that the clinical diagnoses used as phenotypes are genetically heterogeneous. This has led researchers to collect various phenotypes related to the diagnosis, such as detailed symptoms, in the hope that these measurements define more homogeneous disease sub‐types, influenced by a smaller number of genes that will thus be more easily detectable. Latent class analysis can be used to define disease sub‐types from multivariate symptoms under the assumption that the subjects are independent, an assumption that does not hold between members of the same family. We have recently developed a latent class model allowing dependence between the latent disease class status of relatives within nuclear families. In this paper, we propose approaches to use the resulting latent class probabilities in linkage analysis. We present results from a simulation study showing that the latent class approach can provide a substantial gain in power to detect disease genes over the standard heterogeneity approach of Smith and identity‐by‐descent sharing methods applied to the disease diagnosis. Taking into account familial dependence in the latent class model generally provides greater power than assuming independence. In an analysis of autism symptoms in families from the Autism Genetics Research Exchange, linkage signals obtained with latent class‐derived phenotypes were stronger than those obtained using the original autism spectrum disorder diagnosis. Genet. Epidemiol. 2008. © 2008 Wiley‐Liss, Inc.
Functional architecture of verbal and tonal working memory: An FMRI study
Authors: Koelsch Stefan , Schulze Katrin , Sammler Daniela , Fritz Thomas , Müller Karsten , Gruber Oliver
Published: March 2008

This study investigates the functional architecture of working memory (WM) for verbal and tonal information during rehearsal and articulatory suppression. Participants were presented with strings of four sung syllables with the task to remember either the pitches (tonal information) or the syllables (verbal information). Rehearsal of verbal, as well as of tonal information activated a network comprising ventrolateral premotor cortex (encroaching Broca's area), dorsal premotor cortex, the planum temporale, inferior parietal lobe, the anterior insula, subcortical structures (basal ganglia and thalamus), as well as the cerebellum. The topography of activations was virtually identical for the rehearsal of syllables and pitches, showing a remarkable overlap of the WM components for the rehearsal of verbal and tonal information. When the WM task was performed under articulatory suppression, activations in those areas decreased, while additional activations arose in anterior prefrontal areas. These prefrontal areas might contain additional storage components of verbal and tonal WM that are activated when auditory information cannot be rehearsed. As in the rehearsal conditions, the topography of activations under articulatory suppression was nearly identical for the verbal as compared to the tonal task. Results indicate that both the rehearsal of verbal and tonal information, as well as storage of verbal and tonal information relies on strongly overlapping neuronal networks. These networks appear to partly consist of sensorimotor‐related circuits which provide resources for the representation and maintenance of information, and which are remarkably similar for the production of speech and song. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.
The work‐life conundrum: Will HRD become more involved?
Authors: Kahnweiler William M.
Published: March 2008

Although the scholarly and popular literature on work‐life has grown tremendously in the past several decades, and as more and more individuals and organizations grapple with work‐life issues, it appears that HRD's involvement in work‐life has been modest. It is hoped that this article will serve as a catalyst for discussion and debate among HRD scholars and practitioners regarding HRD's current and future involvement in work‐life issues. Suggestions for how our profession can take a more active role in work‐life research and practice are offered.
Effect of dihydrotestosterone on hydrogen peroxide‐induced apoptosis of mouse embryonic stem cells
Authors: Lee Sang Hun , Heo Jung Sun , Lee Min Young , Han Ho Jae
Published: March 2008

Steroid hormones have been reported to activate various signal transducers that trigger a variety of cellular responses. Among these hormones, testosterone has been identified as an antioxidant that protects against cellular damage. Therefore, using mouse embryonic stem (ES) cells as a model system, this study evaluated the effects of dihydrotestosterone (DHT), a biologically active testosterone metabolite, on H2O2‐induced apoptosis. H2O2 increased the release of lactate dehydrogenase (LDH) and DNA fragmentation but reduced the cell viability in a time‐dependent manner (≥8 h). Moreover, H2O2 decreased the level of DNA synthesis and the levels of the cell cycle regulatory proteins [cyclin D1, cyclin E, cyclin‐dependent kinase (CDK) 2, and CDK 4]. These effects of H2O2 were inhibited by a pretreatment with DHT. However, a treatment with flutamide (androgen receptor inhibitor, 10−3 M) abolished the protective effects of DHT. This result was supported by the presence of the androgen receptor in mouse ES cells. The activity of the antioxidant enzyme, catalase, was increased by the DHT treatment but not by a co‐treatment with DHT and flutamide. Using CM‐H2DCFDA (DCF‐DA) for the detection of intracellular H2O2, DHT decreased the intracellular H2O2 levels but flutamide blocked this effect. H2O2 also increased the level of p38 MAPK, JNK/SAPK, and NF‐κB phosphorylation, which were inhibited by the DHT pretreatment. Catalase inhibited the effect of H2O2 on MAPKs and NF‐κB. However, the flutamide treatment abolished the inhibitory effects of DHT on the H2O2‐induced increase in the levels of p38 MAPK, JNK/SAPK, and NF‐κB phosphorylation. DHT inhibited the H2O2‐induced increase in caspase‐3 expression and decreased the level of Bcl‐2 and the cellular inhibitor of apoptosis protein (cIAP)‐2. These effects were abolished by the flutamide treatment. In conclusion, DHT prevents the H2O2‐induced apoptotic cell death of mouse ES cells through the activation of catalase and the downregulation of p38 MAPK, JNK/SAPK, and NF‐κB via the androgen receptor. J. Cell. Physiol. 216: 269–275, 2008. © 2008 Wiley‐Liss, Inc.
Viral vectors for production of recombinant proteins in plants
Authors: Lico Chiara , Chen Qiang , Santi Luca
Published: March 2008

Global demand for recombinant proteins has steadily accelerated for the last 20 years. These recombinant proteins have a wide range of important applications, including vaccines and therapeutics for human and animal health, industrial enzymes, new materials and components of novel nano‐particles for various applications. The majority of recombinant proteins are produced by traditional biological “factories,” that is, predominantly mammalian and microbial cell cultures along with yeast and insect cells. However, these traditional technologies cannot satisfy the increasing market demand due to prohibitive capital investment requirements. During the last two decades, plants have been under intensive investigation to provide an alternative system for cost‐effective, highly scalable, and safe production of recombinant proteins. Although the genetic engineering of plant viral vectors for heterologous gene expression can be dated back to the early 1980s, recent understanding of plant virology and technical progress in molecular biology have allowed for significant improvements and fine tuning of these vectors. These breakthroughs enable the flourishing of a variety of new viral‐based expression systems and their wide application by academic and industry groups. In this review, we describe the principal plant viral‐based production strategies and the latest plant viral expression systems, with a particular focus on the variety of proteins produced and their applications. We will summarize the recent progress in the downstream processing of plant materials for efficient extraction and purification of recombinant proteins. J. Cell. Physiol. 216: 366–377, 2008. © 2008 Wiley‐Liss, Inc.
Topical administration of a multi‐targeted kinase inhibitor suppresses choroidal neovascularization and retinal edema
Authors: Doukas John , Mahesh Sankaranarayana , Umeda Naoyasu , Kachi Shu , Akiyama Hideo , Yokoi Katsutoshi , Cao Jon , Chen Zoe , Dellamary Luis , Tam Betty , Racanelli‐Layton Adrienne , Hood John , Martin Michael , Noronha Glenn , Soll Richard , Campochiaro Peter A.
Published: March 2008

Age‐related macular degeneration, diabetic retinopathy, and retinal vein occlusions are complicated by neovascularization and macular edema. Multi‐targeted kinase inhibitors that inhibit select growth factor receptor tyrosine kinases and/or components of their down‐stream signaling cascades (such as Src kinases) are rationale treatment strategies for these disease processes. We describe the discovery and characterization of two such agents. TG100572, which inhibits Src kinases and selected receptor tyrosine kinases, induced apoptosis of proliferating endothelial cells in vitro. Systemic delivery of TG100572 in a murine model of laser‐induced choroidal neovascularization (CNV) caused significant suppression of CNV, but with an associated weight loss suggestive of systemic toxicity. To minimize systemic exposure, topical delivery of TG100572 to the cornea was explored, and while substantial levels of TG100572 were achieved in the retina and choroid, superior exposure levels were achieved using TG100801, an inactive prodrug that generates TG100572 by de‐esterification. Neither TG100801 nor TG100572 were detectable in plasma following topical delivery of TG100801, and adverse safety signals (such as weight loss) were not observed even with prolonged dosing schedules. Topical TG100801 significantly suppressed laser‐induced CNV in mice, and reduced fluorescein leakage from the vasculature and retinal thickening measured by optical coherence tomography in a rat model of retinal vein occlusion. These data suggest that TG100801 may provide a new topically applied treatment approach for ocular neovascularization and retinal edema. J. Cell. Physiol. 216: 29–37, 2008. © 2008 Wiley‐Liss, Inc.
Customers as contributors and reliable evaluators of creativity in the service industry
Authors: Madjar Nora , Ortiz‐Walters Rowena
Published: March 2008

Using hair stylists, we examined the nature of creativity in a service setting and the impact of customers as part of the social context for employee creativity. We also assessed whether customers could serve as reliable evaluators of creativity. To do so, we collected data from multiple sources: service providers, supervisors, and customers. Results demonstrated that customer input and customer affective‐based trust made significant, positive, and independent contributions to service‐related creativity. Moreover, customers in the service industry proved to be reliable raters of employee creativity, compatible with supervisors. Finally, input and trust were associated differently with service‐related and organization‐related creativity. Copyright © 2008 John Wiley & Sons, Ltd.
Atmospheric chemistry of cyclohexanone: UV spectrum and kinetics of reaction with chlorine atoms
Authors: Iwasaki E. , Matsumi Y. , Takahashi K. , Wallington T. J. , Hurley M.D. , Orlando J. J. , Kaiser E. W. , Calvert J. G.
Published: March 2008

Absolute and relative rate techniques were used to study the reactivity of Cl atoms with cyclohexanone in 6 Torr of argon or 800–950 Torr of N2 at 295 ± 2 K. The absolute rate experiments gave k(Cl + cyclohexanone) = (1.88 ± 0.38) × 10−10, whereas the relative rate experiments gave k(Cl + cyclohexanone) = (1.66 ± 0.26) × 10−10 cm3 molecule−1 s−1. Cyclohexanone has a broad UV absorption band with a maximum cross section of (4.0 ± 0.3) × 10−20 cm2 molecule−1 near 285 nm. The results are discussed with respect to the literature data. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 223–229, 2008
Photophysics and kinetics of naphthopyran derivatives, Part 6: A fundamental system of equations to describe ABC(3k,6ϕ) dynamics. A contribution to the elucidation of [2H]‐naphthopyran kinetics
Authors: Maafi Mounir , Brown Robert G.
Published: March 2008

A new spectrokinetic method free of any assumption is developed in this paper to investigate photochemical systems obeying ABC(3k,6ϕ) kinetic mechanisms that can be characterized by up to 14 unknown parameters for a nonpreconceived mechanism. The mathematical framework of this method is derived as an application from an original formalism previously established to deal with the kinetic law descriptions relating to ABC reactive systems. The necessary number of linearly independent (but nonlinear) equations has been fully defined together with seven other supplementary equations useful as constraints during the iterative calculations. As a practical example, this spectrokinetic method has been used to investigate the dynamics of a new photochromic derivative belonging to the naphthopyran family (2,2‐di(4‐methoxyphenyl)‐5‐carbomethoxy‐6‐(4‐methoxyphenyl)‐9‐methoxy‐2H‐naphtho[1,2‐b]‐pyran). The system of equations has been solved, and the problems of identifiability and distinguishability have been raised with relation to the degeneracy of the kinetic solution. To get more insight into the photochemical and thermal reaction steps involved, a progressive overall discussion leads to several quantitative conclusions whose background sets the dynamics for the present derivative to at least ABC(1k,4ϕ) kinetics. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 268–281, 2008
Weighted isoperimetric inequalities on ℝnand applications to rearrangements
Authors: Betta M. Francesca , Brock Friedemann , Mercaldo Anna , Posteraro M. Rosaria
Published: March 2008

We study isoperimetric inequalities for a certain class of probability measures on ℝntogether with applications to integral inequalities for weighted rearrangements. Furthermore, we compare the solution to a linear elliptic problem with the solution to some “rearranged” problem defined in the domain {x:x1<α(x2, …,xn)} with a suitable functionα(x2, …,xn). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cokernel bundles and Fibonacci bundles
Authors: Brambilla Maria Chiara
Published: March 2008

We are interested in those bundles C on ℙN which admit a resolution of the form

0 → ℂs ⊗ E $$ \buildrel\mu\over\to $$ ℂt ⊗ F → C → 0.

In this paper we prove that, under suitable conditions on (E, F), a generic bundle with this form is either simple or canonically decomposable. As applications we provide an easy criterion for the stability of such bundles on ℙ2 and we prove the stability when E = 𝒪, F = 𝒪(1) and C is an exceptional bundle on ℙN for N ≥ 2. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gorenstein categories and Tate cohomology on projective schemes
Authors: Enochs E. , Estrada S. , García–Rozas J. R.
Published: March 2008

We study Gorenstein categories. We show that such a category has Tate cohomological functors and Avramov–Martsinkovsky exact sequences connecting the Gorenstein relative, the absolute and the Tate cohomological functors. We show that such a category has what Hovey calls an injective model structure and also a projective model structure in case the category has enough projectives. As examples we show that if X is a locally Gorenstein projective scheme then the category 𝔔𝔠𝔬(X) of quasi‐coherent sheaves on X is such a category and so has these features. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Predicting the NMR spectra of nucleotides by DFT calculations: cyclic uridine monophosphate
Authors: Bagno Alessandro , Rastrelli Federico , Saielli Giacomo
Published: March 2008

We present an experimental and quantum chemical NMR study of the mononucleotide cyclic uridine monophosphate in water. Spectral parameters (1H and 13C chemical shifts and 1H1H, 13C1H, 31P13C and 31P1H spin‐spin coupling constants) have been carefully obtained experimentally and calculated using DFT methods including the solvent effect and the conformational flexibility of the solute. This study confirms that the 1H and 13C spectra of polar, flexible molecules in aqueous solution can be predicted with a high level of accuracy, comparable to that obtained for less complex systems. Copyright © 2008 John Wiley & Sons, Ltd.
Polyaniline nanofibers by surfactant‐assisted dilute polymerization for supercapacitor applications
Authors: Subramania Angaiah , Devi Subbarao Lakshmi
Published: March 2008

Polyaniline nanofibers doped with citric acid was prepared by a novel surfactant‐assisted dilute polymerization technique. It was possible to synthesize polyaniline nanofibers without using any organic solvent by easier pathway. Polyaniline salt was characterized by conductivity, FTIR, and X‐ray diffraction studies. The specific capacitance behavior of the polyaniline nanofibers was characterized using cyclic voltammetry which exhibits highest specific capacitance of 298 F g−1. The morphology of the obtained nanofibers was characterized by SEM studies. So, these kinds of specific properties of polyaniline nanofibers could be beneficial to the development of energy storage devices. Copyright © 2008 John Wiley & Sons, Ltd.
Fluorinated polyimide nanocomposites for CO2/CH4 separation
Authors: Rubal Michael , Wilkins Cletus W. , Cassidy Patrick E. , Lansford Chris , Yamada Yasuharu
Published: March 2008

The purpose of this project was to synthesize fluorinated polyimide (PI) nanocomposite membranes in order to study the gas permeation rates and selectivity of carbon dioxide and methane. PIs were synthesized from 2,2‐bis(3,4‐anhydrodicarboxyphenyl)hexafluoropropane (6F dianhydride, 6FDA) and 4,4′‐diaminodiphenyl ether (oxydianiline, ODA) into which were incorporated nanoparticulate additives as follows: in situ TiO2, both plain and treated with dodecyl sulfate surfactant, and organo‐clay (Cloisite®‐10 Å) at loads of 1, 3, and 5 wt% to the polyamic acid. Polyamic acid films were solvent cast, cured at 200°C then post‐cured at 300°C and measured for permeation data and for thermal properties. Glass transition temperatures ranged from 124 to 140°C for the cured PIs and from 142 to 147°C for the post‐cured materials, the nano‐inclusions having little discernable effect on this property. Thermogravimetric analysis (TGA) data show that the inclusion of Cloisite® or TiO2 caused a small decrease of thermal stability from 555°C to about 532 to 541°C. The inclusion of clay causes a decreased permeation rate while the addition of TiO2 improves the rate and selectivity. Treating the nanofillers with surfactant decreases selectivity and marginally increases rate of permeation of CO2. Post‐curing caused a darkening of the composites, but not the neat PI. This heat treatment also resulted in a significantly decreased permeation rate, but a significantly increased selectivity. The resulting material shows superior gas separation properties to the commercially available PI, Matrimid® produced by Ciba‐Geigy. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of rubber type on the curing and physical properties of silica filled rubber compounds
Authors: Shin Chung Ho , Kim Dae Su
Published: March 2008

As environmental regulations are getting stricter, tire industries for automobiles have shown much interest in substituting silica for conventional carbon black partially or entirely. To take full advantage of silica as fillers for rubbers, it is essential to find a reasonable rubber system that shows an excellent performance with silica reinforcement. Therefore, in this study, several different rubber compounds comprising the same amount of silica were prepared with several different rubber systems, respectively. The processability, curing characteristics, and mechanical and viscoelastic properties of the rubber compounds were investigated to analyze the performance of the rubber compounds as tire tread materials. Among the rubber compounds studied, SBR1721 compound comprising natural rubber (NR) and styrene butadiene rubber (SBR) with high styrene content was considered the most appropriate for application to tire tread materials. Copyright © 2008 John Wiley & Sons, Ltd.
Poly(N‐isopropylacrylamide)‐based comb‐type grafted hydrogel with rapid response to blood glucose concentration change at physiological temperature
Authors: Zhang Shi‐Bo , Chu Liang‐Yin , Xu Dan , Zhang Jie , Ju Xiao‐Jie , Xie Rui
Published: March 2008

A new type of glucose‐responsive hydrogel with rapid response to blood glucose concentration change at physiological temperature has been successfully developed. The polymeric hydrogel contains phenylboronic acid (PBA) groups as glucose sensors and thermo‐responsive poly (N‐isopropylacrylamide) (PNIPAM) groups as actuators. The response rate of the hydrogel to environmental glucose concentration change was significantly enhanced by introducing grafted poly(N‐isopropylacrylamide‐co‐3‐acrylamidophenylboronic acid) [poly(NIPAM‐co‐AAPBA)] side chains onto crosslinked poly(NIPAM‐co‐AAPBA) networks for the first time. The synthesized comb‐type grafted poly(NIPAM‐co‐AAPBA) hydrogels showed satisfactory equilibrium glucose‐responsive properties, and exhibited much faster response rate to glucose concentration change than normal type crosslinked poly(NIPAM‐co‐AAPBA) hydrogels at physiological temperature. Such glucose‐responsive hydrogels with rapid response rate are highly attractive in the fields of developing glucose‐responsive sensors and self‐regulated drug delivery systems. Copyright © 2008 John Wiley & Sons, Ltd.
Spironolactone and gastrointestinal bleeding: a population based study
Authors: Russo Antonio , Autelitano Mariangela , Bisanti Luigi
Published: March 2008

Background

Several medical reports showed an increased risk of stomach and duodenum bleeding associated with the use of spironolactone. The objective of this work is to examine the association between upper gastrointestinal (UGI) bleeding and exposure to spironolactone, using a population‐based cohort design.

Methods

Using the pharmaceutical prescriptions from 2000 to 2006, a cohort was identified of residents in Milan (Italy) with chronic exposure to spironolactone or other diuretic drugs. The main outcome was defined as the hospital admission for UGI bleeding or ulcers. To control for potential bias related to spironolactone use, the propensity score was estimated. Then, each patient treated with spironolactone was randomly matched with one treated with other diuretics and having the same propensity score using the caliper matching method. Proportional hazard models were fitted by computing hazard ratios (HR) and the corresponding 95% confidence intervals (95%CI).

Results

A total of 53 550 unexposed and 10 564 exposed to spironolactone were identified. Overall in the study period, 174 patients (3.2%) developed UGI bleeding in the unexposed and 51 (4.8%) in the exposed group. HR for UGI bleeding for the spironolactone exposed group was 1.94 (95%CI 1.42–2.65).

The sensitivity analysis based on the matched design using the propensity score showed a statistically significant twofold increase of gastrointestinal bleeding only among subjects exposed to high spironolactone dose (HR 2.50; 95%CI 1.08–5.79).

Conclusions

Results from a large population based study confirm that spironolactone increases the risk of UGI bleeding. Copyright © 2008 John Wiley & Sons, Ltd.
Specificity of immobilized porcine pepsin in H/D exchange compatible conditions
Authors: Hamuro Yoshitomo , Coales Stephen J. , Molnar Kathleen S. , Tuske Steven J. , Morrow Jeffrey A.
Published: March 2008

Statistical analysis of data from 39 proteins (13 766 amino acid residues) digested with immobilized porcine pepsin under conditions compatible with hydrogen/deuterium (H/D) exchange (<1°C, <30 s) was performed to examine pepsin cleavage specificity. The cleavage of pepsin was most influenced by the amino acid residue at position P1. Phe and Leu are favored residues each with a cleavage probability greater than 40%. His, Lys, Arg, or Pro residues prohibit cleavage when found at the P1 position. Pro also cannot be at position P2 (cleavage probability <0.3%). Occupation of the P3 position by His, Lys, or Arg, or occupation of the P2′ position by Pro, also leads to very little cleavage (cleavage probability <1.7%). The average cleavage probability over the entire data set was 13.6%, which is slightly lower than the value previously obtained by Powers et al. (14.8%). This is due, in part, to the larger protein sizes used in the current study. While the specificity of pepsin was similar to that previously observed, higher selectivity was observed in the present study due to less experimental variation in the conditions used to generate our database. Copyright © 2008 John Wiley & Sons, Ltd.
Short‐phase training on a virtual reality simulator improves technical performance in tele‐robotic surgery
Authors: Balasundaram Indran , Aggarwal Rajesh , Darzi Ara
Published: March 2008

Background

The da Vinci tele‐robot necessitates the acquisition of new skills and surgical educators must develop standardized training programmes. It is possible that virtual reality (VR) computer simulation maybe used and it is necessary to define whether a simulator is an appropriate tool.

Methods

Ten surgical novices performed a series of five tasks, ten times on a commercially available VR robotic simulator. Two experts repeated the series of tasks twice in an attempt to validate the simulator.

Results

Each of the five tasks displayed statistically significant learning curves. Error scores did not improve significantly over successive repetitions except in one task. The experts completed two of the tasks in a significantly faster time.

Conclusions

Practice sessions on a VR simulator improve technical performance. The simulator enables surgeons to mount the early part of the learning curve within a laboratory environment, which may lead to a more effective training programme. Copyright © 2008 John Wiley & Sons, Ltd.
Characterization challenges for nanomaterials
Authors: Baer D. R. , Amonette J. E. , Engelhard M. H. , Gaspar D. J. , Karakoti A. S. , Kuchibhatla S. , Nachimuthu P. , Nurmi J. T. , Qiang Y. , Sarathy V. , Seal S. , Sharma A. , Tratnyek P. G. , Wang C.‐M.
Published: March 2008

Nanostructured materials are increasingly subject to nearly every type of chemical and physical analysis possible. Due to their small sizes, there is a significant focus on tools with high spatial resolution. It is also natural to characterize nanomaterials using tools designed to analyze surfaces, because of their high surface area. Regardless of the approach, nanostructured materials present a variety of obstacles to adequate, useful, and needed analysis. Case studies of measurements on ceria and iron metal‐core/oxide‐shell nanoparticles are used to introduce some of the issues that frequently need to be addressed during analysis of nanostructured materials. We use a combination of tools for routine analysis including X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and x‐ray diffraction (XRD) and apply several other methods as needed to obtain essential information. The examples provide an introduction to other issues and complications associated with the analysis of nanostructured materials including particle stability, probe effects, environmental effects, specimen handling, surface coating, contamination, and time. Copyright © 2008 John Wiley & Sons, Ltd.
Nanomechanical properties of ion‐implanted Si
Authors: Nagy P. M. , Aranyi D. , Horváth P. , Pető G. , Kálmán E.
Published: March 2008

The nanomechanical properties of single crystalline silicon samples has gained wide attention in recent years, because of the abnormal loading effects, caused by the pressure‐induced phase transformation of silicon. To further enlighten the phenomenon bulk, ion‐implanted, single crystal Si samples have been studied by nanoindentation experiments, and by atomic force microscopy (AFM). The implantation of Si wafers was carried out by P ions at 40 KeV energy, influencing the defect density and structure of the Si material in shallow depth at the surface. Our experiments provide consistent evaluation of Young's modulus and hardness of the samples (measured with Berkovich‐, spherical‐ and cube corner indenters), statistics of the pop‐in and pop‐out effects during the indentation, and interesting results about the piling‐up behavior of the Si material. The plastic work on the sample was also evaluated in cyclic indentation experiments by calculating the area of the hysteresis loops in the load curve. Copyright © 2008 John Wiley & Sons, Ltd.
Formation of aldehyde‐ and carboxy‐terminated self‐assembled monolayers on SiO2 surfaces
Authors: Hozumi Atsushi , Taoda Hiroshi , Saito Takao , Shirahata Naoto
Published: March 2008

Aldehyde (CHO)‐ and carboxy (COOH)‐terminated self‐assembled monolayers (SAMs) were prepared on silicon substrates covered with native oxide (SiO2/Si) based on the chemisorption of triethoxysilylundecanal (TESUD) molecules and subsequent photooxidation of the terminal groups using 172‐nm vacuum UV light in wavelength, respectively. In this study, we have particularly focused on the effects of atmospheric pressure during vacuum UV irradiation on the degree of the SAM photooxidation. When irradiation was conducted under a residual pressure of 103 Pa, the hydrophobic TESUD‐SAM surface became hydrophilic and its water‐contact angle fell from approximately 80° to less than 5° within 1 min. Film thickness also decreased from about 1.2 nm to about 0.3 nm, indicating the complete photodecomposition of the organic parts of the TESUD‐SAM. On the other hand, in the case of 105 Pa, by selecting an appropriate time for vacuum UV irradiation, we were able to control the degree of photooxidation of the TESUD‐SAM. Using a vacuum UV irradiation of 25 min at 105 Pa, only the topmost region of the TESUD‐SAM was successfully photooxidized into COOH groups without any marked change in both film thickness and surface morphology, as evidenced by water‐contact angle data, ellipsometry, X‐ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Copyright © 2008 John Wiley & Sons, Ltd.
Interfacial characterization of chemical solution‐deposited thin films of PbSe on GaAs(100)
Authors: Shandalov Michael , Rozenblat Avraham , Kedem Nir , Popovitz‐Biro Ronit , Golan Yuval
Published: March 2008

The microstructure and composition of the interfacial layer between chemically deposited PbSe and GaAs substrates were studied using high‐resolution transmission electron microscopy (HRTEM), Auger electron spectroscopy (AES), x‐ray photoelectron spectroscopy (XPS) and energy‐filtered TEM.

The thickness of the interfacial layer varied significantly from direct contact of the film with the substrate to 5 nm in the thickest regions. The results established the presence of a discontinuous, amorphous intermediate layer of Ga2O3 at the PbSe/GaAs interface. Copyright © 2008 John Wiley & Sons, Ltd.