bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural insights into the binding of hepatitis B virus core peptide to HLA‐A2 alleles: Towards designing better vaccines
Authors: Liu Jingxian , Chen Kenneth Y. , Ren Ee C.
Published: May 2011

Binding of specific antigenic peptides with human leukocyte antigen (HLA) molecules is a prerequisite for the initiation of T‐cell responses and structural information about the peptide–HLA complex is essential for the detailed understanding of such interactions. HLA‐A2 is the most prevalent HLA allele globally but aside from A*02:01 there is a significant lack of crystal structures, particularly for alleles that occur in high frequencies among Asian populations. Here, we report three HLA‐A2 structures with the immunodominant hepatitis B core antigen 18–27 (HBcAg18–27) epitope, namely A*02:03, A*02:06, and A*02:07 at resolutions of 2.16, 1.70, and 1.75 Å respectively. This comparative analysis reveals that minor polymorphic residue changes between different HLA alleles can induce significant alterations in the major histocompatibility complex–peptide interface, and introduce conformational changes in the p3–p8 peptide region. Circular dichroism analysis demonstrated the HLA‐A2–peptide complexes to have a hierarchy of thermostability and binding affinity in the order of A*02:06>A*02:07>A*02:01>A*02:03. Our findings provide structural insights into the varied HLA‐A2 allele binding of the hepatitis B core antigen 18–27 epitope and the data suggest that chemical modifications of the peptide side chains could be a promising strategy to modulate and improve HLA‐A2–peptide binding affinity for vaccine design.
Synthesis and Characterization of a Series of Ruthenium Tris(β‐diketonato) Complexes by an UHV‐STM Investigation and Numerical Calculations
Authors: Munery Sabrina , Ratel‐Ramond Nicolas , Benjalal Youness , Vernisse Loranne , Guillermet Olivier , Bouju Xavier , Coratger Roland , Bonvoisin Jacques
Published: May 2011

A series of ruthenium tris(β‐diketonate) complexes was investigated by using electrochemistry, UV/Vis spectroscopy, 1H NMR and 13C NMR spectroscopy and FAB mass spectroscopy. Several new mononuclear mixed‐ligand ruthenium(III) complexes were prepared: with three dibenzoylmethanate ions (dbm) {[Ru(dbm)3] (1)}, one or two acetylacetonate ions (2,4‐pentanedionate, acac) {[Ru(dbm)2(acac)] (2), [Ru(dbm)(acac)2] (3)}, two acetonitrile ligands {[Ru(dbm)2(CH3CN)2][CF3SO3] (4)} or a functionalized acetylacetonate ion {[Ru(dbm)2(acac‐I)] (5) (acac‐I = 3‐iodo‐2,4‐pentanedionate ion), [Ru(dbm)2(acac‐Br)] (6) (acac‐Br = 3‐bromo‐2,4‐pentanedionate ion)}. In addition, X‐ray structures for complexes 1, 2, 3, 4 and 6 were determined. Scanning tunnelling microscopy measurements at liquid He temperature and in anultra‐high vacuum (UHV‐STM) were conducted on complex 1 on a Ag(111) surface. This indicates that the complex can be successfully evaporated and observed after adsorption onto a metallic substrate. Analysis of the STM images, supported by adsorption and STM image calculations, demonstrates that the molecules exist in two stable forms when adsorbed onto the surface.
The role of self‐esteem contingencies in the distinction between obsessive and harmonious passion
Authors: Mageau Geneviève A. , Carpentier Joëlle , Vallerand Robert J.
Published: May 2011

The Dualistic Model of Passion (Vallerand et al., 2003) shows that people can experience a harmonious or an obsessive passion toward an activity. Mageau and Vallerand (2007; Mageau et al., 2009) have argued that self‐related processes, such as contingencies of self‐worth, are central in the distinction between the two types of passion. Specifically, it was proposed that people with an obsessive passion rely more heavily on their passionate activity to derive self‐esteem than people with a harmonious passion such that they should experience self‐esteem fluctuations as a function of their performances in their passionate activity. This study tested this hypothesis. Using self‐reports, results first showed that the more people have an obsessive passion the more they report experiencing self‐esteem fluctuations that covary with their performances in their passionate activity. In contrast, people with a harmonious passion did not report experiencing more, or less, self‐esteem fluctuations. Second, hierarchical linear modeling confirmed that, in a real‐life setting, the more people report an obsessive passion toward a card game, the greater is the impact of performance on their state self‐esteem. Taken together, these findings suggest that obsessive, but not harmonious, passion triggers contingencies between people's self‐esteem and their passionate activity. Copyright © 2011 John Wiley & Sons, Ltd.
Cyclic Voltammetry Study of the Mn‐Substituted Polyoxoanions [MnII4(H2O)2(H4AsW15O56)2]18− and [((MnIIOH2)MnII2PW9O34)2(PW6O26)]17−: Electrodeposition of Manganese Oxides Electrocatalysts for Dioxygen Reduction
Authors: Ammam Malika , Keita Bineta , Nadjo Louis , Mbomekalle Israel‐Martyr , Ritorto Michelle D. , Anderson Travis M. , Neiwert Wade A. , Hill Craig L. , Fransaer Jan
Published: May 2011

The electrochemical behavior of two manganese (Mn)‐substituted polyoxoanions, the dissymmetrical Dawson sandwich‐type [MnII4(H2O)2(H4AsW15O56)2]18− and the Keggin sandwich banana‐shaped [((MnIIOH2)MnII2PW9O34)2(PW6O26)]17− is investigated. At pH 5, the oxidation of the MnII‐centers results in one oxidation wave for [MnII4(H2O)2(H4AsW15O56)2]18− and two oxidation waves for [((MnIIOH2)MnII2PW9O34)2(PW6O26)]17−. To the best of our knowledge, presence of the second Mn‐based wave is rarely observed in the electrochemistry of Mn‐containing polyoxometalates. Deposition of Mn‐oxides electrocatalysts for dioxygen reduction is noticed by cyclic voltammetry, which can be distinguished by the significant positive shift in potentials of the dioxygen reduction reaction.
Genotyping of single nucleotide polymorphism in γ‐glutamyl hydrolase gene by capillary electrophoresis
Authors: Cheng Hui‐Ling , Chiou Shyh‐Shin , Liao Yu‐Mei , Chen Yen‐Ling , Wu Shou‐Mei
Published: May 2011

The γ‐glutamyl hydrolase (GGH) gene plays an important role in methotrexate (MTX) metabolism, ensuring that MTX polyglutamates (MTX‐(Glu)n) could be converted back into MTX. Accumulation of MTX‐(Glu)n is a problem in MTX therapy. SNP 452 C>T has been reported to associate with lower catalytic activity and higher accumulation of long‐chain MTX‐(Glu)n in patients treated with higher doses of MTX treatment. We propose and establish a simple and effective CE method for detecting SNP in GGH gene. The DNA samples after amplification were analyzed by SSCP‐CE method. The CE conditions were generated by using 1× TBE buffer containing 1.5% w/v hydroxypropyl methyl cellulose under reverse polarity at 25°C. This method was applied to detect genotyping of acute lymphoblastic leukemia patients receiving MTX treatment. The results were confirmed by DNA sequencing with good agreement. Concentrations of MTX‐(Glu)n in whole blood were analyzed by on‐line stacking CE method. MTX‐(Glu)n levels and genotypes in GGH gene of acute lymphoblastic leukemia patients were evaluated. The SSCP‐CE method was found to be feasible for SNP screening in the GGH gene.
Analysis of mutations in the Pig‐a gene of spleen T‐cells from N‐ethyl‐N‐nitrosourea‐treated fisher 344 rats
Authors: Miura Daishiro , Shaddock Joseph G. , Mittelstaedt Roberta A. , Dobrovolsky Vasily N. , Kimoto Takafumi , Kasahara Yoshinori , Heflich Robert H.
Published: May 2011

A rapid in vivo somatic cell gene mutation assay is being developed that measures mutation in the endogenous X‐linked phosphatidylinositol glycan, class A gene (Pig‐a). The assay detects Pig‐a mutants by flow cytometric identification of cells deficient in glycosylphosphatidyl inositol (GPI) anchor synthesis. GPI‐deficient, presumed Pig‐a mutant cells also can be detected in a cloning assay that uses proaerolysin (ProAER) selection. Previously, we demonstrated that ProAER‐resistant (ProAERr) rat spleen T‐cells have mutations in the Pig‐a gene. In the present study, we report on a more complete analysis of ProAERr rat spleen T‐cell mutants and describe a mutation spectrum for mutants isolated from rats 4 weeks after treatment with three consecutive doses of 35.6 mg/kg N‐ethyl‐N‐nitrosourea (ENU). We identified a total of 55 independent mutations, with the largest percentage (69%) involving basepair substitution at A:T. The overall spectrum of Pig‐a gene mutations was consistent with the types of DNA adducts formed by ENU and was very similar to what has been described for in vivo ENU‐induced mutation spectra in other rodent reporter genes (e.g., in the endogenous Hprt gene and transgenic shuttle vectors). These data are consistent with the rat Pig‐a assay detecting test‐agent‐induced mutational responses. Environ. Mol. Mutagen., 2011. Published 2011 Wiley‐Liss, Inc.
Life‐cycle reliability of RC bridge piers under seismic and airborne chloride hazards
Authors: Akiyama Mitsuyoshi , Frangopol Dan M. , Matsuzaki Hiroshi
Published: May 2011

Over the last two decades, the probabilistic assessment of reinforced concrete (RC) structures under seismic hazard has been developed rapidly. However, little attention has been devoted to the assessment of the seismic reliability of corroded structures. For the life‐cycle assessment of RC structures in a marine environment and earthquake‐prone regions, the effect of corrosion due to airborne chlorides on the seismic capacity needs to be taken into consideration. Also, the effect of the type of corrosive environment on the seismic capacity of RC structures has to be quantified.

In this paper, the evaluation of the displacement ductility capacity based on the buckling model of longitudinal rebars in corroded RC bridge piers is established, and a novel computational procedure to integrate the probabilistic hazard associated with airborne chlorides into life‐cycle seismic reliability assessment of these piers is proposed. The seismic demand depends on the results of seismic hazard assessment, whereas the deterioration of seismic capacity depends on the hazard associated with airborne chlorides. In an illustrative example, an RC bridge pier was modeled as single degree of freedom (SDOF). The longitudinal rebars buckling of this pier was considered as the sole limit state when estimating its failure probability. The findings show that the life‐cycle reliability of RC bridge piers depends on both the seismic and airborne chloride hazards, and that the cumulative‐time failure probabilities of RC bridge piers located in seismic zones can be dramatically affected by the effect of airborne chlorides. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis and optical properties of a bis(diphenylphosphino)dithienosilole‐digold(I) complex
Authors: Ohshita Joji , Tominaga Yuta , Mizumo Tomonobu , Kuramochi Yusuke , Higashimura Hideyuki
Published: May 2011

Treatment of 2,6‐bis(diphenylphosphino)‐4,4‐bis(4‐n‐butylphenyl)dithienosilole with chloro(dimethylsulfide)gold(I) in acetone gave the corresponding digold complex as pale green solids. The complex was highly emissive and showed blue photoluminescence with the quantum efficiencies of Φ = 0.99 and 0.30 for its solution and powders, respectively. The complex showed good film forming properties and its spin coating from the toluene solution afforded a thin solid film that also showed emissive properties with Φ = 0.08 © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:514–517, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20715
Free radical addition of α‐telluroesters to alkenes
Authors: Kambe Nobuaki , Han Li‐Biao , Fujiwara Shin‐ichi , Sonoda Noboru
Published: May 2011

α‐(Phenyltelluro)esters 2 reacted with electron‐rich alkenes 3 in the presence of a catalytic amount of azobisisobutyronitrile (AIBN) as an initiator to give the corresponding addition products 4. This carbotelluration of alkenes proceeded via a radical chain mechanism involving the bimolecular homolytic substitution (SH2) reaction on tellurium as the key step, wherein tellurium plays an important role in a kinetic fashion to realize the rapid group transfer process resulting in suppressing the competing olefin polymerization. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:518–522, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20716
Conjugate addition of vinylic organocuprates generated via transmetalation of phenylseleno‐substituted vinylzirconates: Functionalization at the 4‐position of enones
Authors: Segi Masahito , Suzuki Masahiro , Shintaku Kazuki , Maeda Hajime
Published: May 2011

Hydrozirconation of propargylic selenides (1) or 4‐phenylseleno‐1‐butyne (2) with Cp2ZrHCl, followed by in situ transmetalation to cuprate (Me2Cu(CN)Li2) and addition of enones, led to the formation of 1,4‐adducts in good yields. The adducts derived from 1 were subjected to oxidation with H2O2 to afford allylic alcohol derivatives via [2,3] sigmatropic rearrangement of allylic selenides. On the other hand, the oxidation of the products derived from 2 gave the corresponding ketones having a conjugated diene moiety at the β‐position via selenoxide elimination. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:545–552, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20720
Choline supplementation mitigates trace, but not delay, eyeblink conditioning deficits in rats exposed to alcohol during development
Authors: Thomas Jennifer D. , Tran Tuan D.
Published: May 2011

Children exposed to alcohol prenatally suffer from a range of physical, neuropathological, and behavioral alterations, referred to as fetal alcohol spectrum disorders (FASD). Both the cerebellum and hippocampus are affected by alcohol exposure during development, which may contribute to behavioral and cognitive deficits observed in children with FASD. Despite the known neuropathology associated with prenatal alcohol exposure, many pregnant women continue to drink (heavy drinkers, in particular), creating a need to identify effective treatments for their children who are adversely affected by alcohol. We previously reported that choline supplementation can mitigate alcohol's effects on cognitive development, specifically on tasks which depend on the functional integrity of the hippocampus. The present study examined whether choline supplementation could differentially mitigate alcohol's effects on trace eyeblink classical conditioning (ECC, a hippocampal‐dependent task) and delay ECC (a cerebellar‐dependent task). Long‐Evans rats were exposed to 5.25 g/kg/day alcohol via gastric intubation from postnatal days (PD) 4–9, a period of brain development equivalent to late gestation in humans. A sham‐intubated control group was included. From PD 10–30, subjects received subcutaneous injections of 100 mg/kg choline chloride or vehicle. Beginning on PD 32–34, subjects were trained on either delay or trace eyeblink conditioning. Performance of subjects exposed to alcohol was significantly impaired on both tasks, as indicated by significant reductions in percentage and amplitude of conditioned eyeblink responses, an effect that was attenuated by choline supplementation on the trace, but not delay conditioning task. Indeed, alcohol‐exposed subjects treated with choline performed at control levels on the trace eyeblink conditioning task. There were no significant main or interactive effects of sex. These data indicate that choline supplementation can significantly reduce the severity of trace eyeblink conditioning deficits associated with early alcohol exposure, even when administered after the alcohol insult is complete. These findings have important implications for the treatment of fetal alcohol spectrum disorders. © 2011 Wiley Periodicals, Inc.
Post‐training cocaine exposure facilitates spatial memory consolidation in C57BL/6 mice
Authors: Iñiguez Sergio D. , Charntikov Sergios , Baella Shelley A. , Herbert Matthew S. , Bolaños‐Guzmán Carlos A. , Crawford Cynthia A.
Published: May 2011

In this study, we examined the ability of post‐training injections of cocaine to facilitate spatial memory performance using the Morris water maze (MWM). We also investigated the role that hippocampal protein kinase A (PKA) and extracellular signal‐regulated kinase 1/2 (ERK) signaling may play in cocaine‐mediated spatial memory consolidation processes. Male and female C57BL/6 mice were first trained in a MWM task (eight consecutive trials) then injected with cocaine (0, 1.25, 2.5, 5, or 20 mg/kg), and memory for the platform location was retested after a 24 h delay. Cocaine had a dose‐dependent effect on spatial memory performance because only the mice receiving 2.5 mg/kg cocaine displayed a significant reduction in latency to locate the platform. No sex differences in MWM performance were observed; however, females showed higher hippocampal levels of PKA when compared with males. A second experiment demonstrated that 2.5 mg/kg cocaine enhanced MWM performance only when administered within 2, but not 4 h after spatial training. We also found that cocaine (2.5 mg/kg) increased ERK2 phosphorylation within the hippocampus and one of its downstream targets (ribosomal S6 kinase), a mechanism that may be responsible, at least in part, for the enhanced cocaine‐mediated spatial memory performance. Overall, these data demonstrate that a low dose of cocaine (2.5 mg/kg) administered within 2 h after training facilitates MWM spatial memory performance in C57BL/6 mice. © 2011 Wiley Periodicals, Inc.
Context‐dependent modulation of hippocampal and cortical recruitment during remote spatial memory retrieval
Authors: Lopez Joëlle , Herbeaux Karin , Cosquer Brigitte , Engeln Michel , Muller Christophe , Lazarus Christine , Kelche Christian , Bontempi Bruno , Cassel Jean‐Christophe , de Vasconcelos Anne Pereira
Published: May 2011

According to systems consolidation, as hippocampal‐dependent memories mature over time, they become additionally (or exclusively) dependent on extra‐hippocampal structures. We assessed the recruitment of hippocampal and cortical structures on remote memory retrieval in a performance‐degradation resistant (PDR; no performance degradation with time) versus performance‐degradation prone (PDP; performance degraded with time) context. Using a water‐maze task in two contexts with a hidden platform and three control conditions (home cage, visible platform with or without access to distal cues), we compared neuronal activation (c‐Fos imaging) patterns in the dorsal hippocampus and the medial prefrontal cortex (mPFC) after the retrieval of recent (5 days) versus remote (25 days) spatial memory. In the PDR context, the hippocampus exhibited greater c‐Fos protein expression on remote than recent memory retrieval, be it in the visible or hidden platform group. In the PDP context, hippocampal activation increased at the remote time point and only in the hidden platform group. In the anterior cingulate cortex, c‐Fos expression was greater for remote than for recent memory retrieval and only in the PDR context. The necessity of the mPFC for remote memory retrieval in the PDR context was confirmed using region‐specific lidocaine inactivation, which had no impact on recent memory. Conversely, inactivation of the dorsal hippocampus impaired both recent and remote memory in the PDR context, and only recent memory in the PDP context, in which remote memory performance was degraded. While confirming that neuronal circuits supporting spatial memory consolidation are reorganized in a time‐dependent manner, our findings further indicate that mPFC and hippocampus recruitment (i) depends on the content and perhaps the strength of the memory and (ii) may be influenced by the environmental conditions (e.g., cue saliency, complexity) in which memories are initially formed and subsequently recalled. © 2011 Wiley Periodicals, Inc.
Activation of immobility‐related hippocampal theta by cholinergic septohippocampal neurons during vestibular stimulation
Authors: Tai Siew Kian , Ma Jingyi , Ossenkopp Klaus‐Peter , Leung L. Stan
Published: May 2011

The vestibular system has been suggested to participate in spatial navigation, a function ascribed to the hippocampus. Vestibular stimulation during spatial navigation activates a hippocampal theta rhythm (4–10 Hz), which may enhance spatial processing and motor response. We hypothesize that a cholinergic, atropine‐sensitive theta is generated during passive whole‐body rotation in freely behaving rats. Hippocampal EEGs were recorded by implanted electrodes in CA1 while rats were rotated on a vertical axis, for a minute or longer, at different angular velocities. Rotation induced a continuous hippocampal theta rhythm while the rat was immobile, in both light and dark conditions. Theta peak frequency showed a significant increase during high (50–70 rpm) as compared with a lower (20–49 rpm) rotational velocity. Rotation‐induced theta was abolished by muscarinic receptor antagonist atropine sulfate (50 mg/kg i.p.) but not by atropine methyl nitrate (50 mg/kg i.p.), which did not pass the blood‐brain barrier. Theta was attenuated in rats in which cholinergic neurons in the medial septum (MS) were lesioned with 192 IgG‐saporin (0.14 μg in 0.4 μl), as confirmed by depletion of MS cells immunoreactive to choline acetyltransferase and an absence of acetylcholinesterase staining in the hippocampus. Bilateral lesion of the vestibular receptors by sodium arsanilate (30 mg in 0.1 ml, intratympanically) also attenuated the rotation‐induced theta rhythm. In intact rats, field excitatory postsynaptic potentials (fEPSPs) in CA1 evoked by commissural stimulation were smaller during walking or rotation as compared with during immobility. Modulation of fEPSP was absent following atropine sulfate in intact rats and in 192 IgG‐saporin lesion rats. In summary, this is the first report of a continuous atropine‐sensitive hippocampal theta in the rat induced by vestibular stimulation during rotation, and accompanied by cholinergic modulation of hippocampal synaptic transmission. Vestibular‐activated septohippocampal cholinergic activity could be an important component in sensorimotor processing and spatial memory. © 2011 Wiley Periodicals, Inc.
STARTING BUSINESSES THROUGH RECIPROCAL INFORMAL SUBCONTRACTING: EVIDENCE FROM THE INFORMAL GARMENT INDUSTRY IN HO CHI MINH CITY
Authors: Goto Kenta
Published: May 2011

This paper addresses the question of how cash constrained and inexperienced people in developing countries can start their businesses by looking at the informal garment industry of Ho Chi Minh City, Vietnam. This industry caters primarily for the domestic local markets and produce garments through local subcontracting systems. These subcontracting systems are embedded in social networks, which are based on kinship and territorial relationships, and are reciprocal in nature. This paper argues that in the absence of formal institutions supporting business start‐ups, such reciprocal informal subcontracting could play major roles. Copyright © 2011 John Wiley & Sons, Ltd.
In vitro binding profile and radiosynthesis of a novel 18F‐labeled azaspirovesamicol analog as potential ligand for imaging of the vesicular acetylcholine transporter
Authors: Wenzel Barbara , Hiller Achim , Fischer Steffen , Sorger Dietlind , Deuther‐Conrad Winnie , Scheunemann Matthias , Brust Peter , Sabri Osama , Steinbach Jörg
Published: May 2011

Radiolabeled vesamicol analogs are promising candidates as ligands for the vesicular acetylcholine transporter (VAChT) to enable in vivo imaging of early cholinergic degenerations in brain. The 4‐fluorobenzoyl‐substituted azaspirovesamicol derivative FBASV is one out of six novel vesamicol analogs and demonstrated most appropriate in vitro binding data. 18F‐radiolabeling was performed by microwave‐assisted nucleophilic aromatic substitution of the corresponding nitro precursor and two methods were developed for the purification of [18F]FBASV. Utilizing method A, the remaining nitro precursor was reduced to its corresponding amine, which was separated via semi‐preparative HPLC on a conventional RP column. In method B a phenyl column was used for the direct separation of [18F]FBASV and its nitro precursor, resulting in a change of the elution order and better separation parameters. Thus, [18F]FBASV was synthesized with a RCY of 16–18%, a specific activity >300 GBq/µmol, and a radiochemical purity of >99.5% suitable for future in vivo studies. Copyright © 2011 John Wiley & Sons, Ltd.
Raman‐induced Kerr effect spectroscopy of single‐wall carbon nanotubes aqueous suspensions in the range 0.1–10 and 100–250 cm−1
Authors: Bunkin A. F. , Pershin S. M.
Published: May 2011

Here, we study a low (less than 0.1 µg/ml) concentration aqueous suspension of single‐wall carbon nanotubes (SWNTs) by Raman‐induced Kerr effect spectroscopy (RIKES) in the spectral bands 0.1–10 and 100–250 cm−1. This method is capable of carrying out direct investigation of SWNT hydration layers. A comparison of RIKES spectra of SWNT aqueous suspension and that of milli‐Q water shows a considerable growth in the intensity of low wavenumber Raman modes. These modes in the 0.1–10 cm−1 range are attributed to the rotational transitions of H2O2 and H2O molecules. We explain the observed intensity increase as due to the production of hydrogen peroxide and the formation of a low‐density depletion layer on the water–nanotube interface. A few SWNT radial breathing modes (RBM)are observed (ωRBM = 118.5, 164.7 and 233.5 cm−1) in aqueous suspension, which allows us to estimate the SWNT diameters (∼2.0, 1.5, and 1 nm, respectively). Copyright © 2011 John Wiley & Sons, Ltd.
UV resonance Raman spectroscopy probes the amide II′p band position in short breast milk peptides with antioxidant activity
Authors: Pripotnev Stahs , Tsopmo Apollinaire , Friel James K. , Ianoul Anatoli
Published: May 2011

UV resonance Raman spectroscopic study of six short proline‐containing peptides with antioxidant activity isolated from human breast milk was performed. The amide II′ proline spectroscopic band was used to estimate relative cis trans isomerization state of proline amide bonds in the different peptides. Antioxidant activity of the peptides was determined using 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) assay and linoleic acid emulsion assay. Although no clear correlation between the amide II′p position and antioxidant activity of the peptides was observed, they both were found to be sensitive to the presence and/or relative position of proline and tyrosine residues in the peptide. Copyright © 2011 John Wiley & Sons, Ltd.
Online coupling of molecularly imprinted solid‐phase extraction to HPLC for determination of trace tetracycline antibiotic residues in egg samples
Authors: Jing Tao , Niu Jiwei , Xia Huan , Dai Qing , Zheng Hongyan , Hao Qiaolin , Mei Surong , Zhou Yikai
Published: May 2011

An automated system has been developed for the determination of trace tetracycline antibiotics (TCs) in egg samples, based on online molecularly imprinted solid‐phase extraction (MISPE) coupling with high‐performance liquid chromatography (HPLC). Oxytetracycline and chlortetracycline were chosen as mixed templates to synthesize highly selective molecularly imprinted polymers for online extraction. Under the optimal online MISPE‐HPLC condition, 10 mL egg samples were injected into the MISPE column and then the matrix was washed out. By rotating the switching valve, TCs were transferred to the analytical column and then separated by HPLC. Because sample pretreatment and chromatographic separation were carried out simultaneously, the whole analytical time (18 min) was significantly shortened compared with conventional offline techniques. The detection limits ranged from 0.8 to 1.3 ng/g. The enhancement factors were in the range of 159–410. The spiked recoveries of TCs in real egg samples ranged from 91.6 to 107.6% and the relative standard deviations (RSDs) were not higher than 4.0%.
Modelling by partial least squares the relationship between the HPLC mobile phases and analytes on phenyl column
Authors: Markopoulou Catherine K. , Kouskoura Maria G. , Koundourellis John E.
Published: May 2011

Twenty‐five descriptors and 61 structurally different analytes have been used on a partial least squares (PLS) to latent structure technique in order to study chromatographically their interaction mechanism on a phenyl column. According to the model, 240 different retention times of the analytes, expressed as Y variable (log k), at different % MeOH mobile‐phase concentrations have been correlated with their theoretical most important structural or molecular descriptors. The goodness‐of‐fit was estimated by the coefficient of multiple determinations r2 (0.919), and the root mean square error of estimation (RMSEE=0.1283) values with a predictive ability (Q2) of 0.901. The model was further validated using cross‐validation (CV), validated by 20 response permutations r2 (0.0, 0.0146), Q2 (0.0, −0.136) and validated by external prediction. The contribution of certain mechanism interactions between the analytes, the mobile phase and the column, proportional or counterbalancing is also studied. Trying to evaluate the influence on Y of every variable in a PLS model, VIP (variables importance in the projection) plot provides evidence that lipophilicity (expressed as Log D, Log P), polarizability, refractivity and the eluting power of the mobile phase are dominant in the retention mechanism on a phenyl column.
Comparison Between First‐timers and Repeaters for Relationship Marketing Implications
Authors: Choo Hyungsuk , Petrick James F.
Published: May 2011

This research note examines how different relationships affect visitors' tourism experiences at agritourism encounters, recognizing the differences between repeaters and first‐timers from a relationship marketing perspective. Results from a survey of 431 visitors to farms in Texas found that most of relationships with service providers, other customers and companions were important but differently related to satisfaction. By examining the differences and similarities between first‐timers and repeaters, this study suggests that visitors' relationships not only with service providers but also with other customers and companions should be embraced into the components of relationship marketing models in tourism. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis and Characterization of Epoxy/MCDEA Networks Modified with Imidazolium‐Based Ionic Liquids
Authors: Soares Bluma Guenther , Livi Sebastien , Duchet‐Rumeau Jannick , Gerard Jean‐François
Published: May 2011

Epoxy‐networked materials containing N,N'‐dioctadecylimidazolium iodide are prepared by curing a mixture of DGEBA and different ratios of the ionic liquid with MCDEA at high temperature. The presence of ionic liquid results in an increase of the storage modulus and a decrease of the glass transition temperature, as indicated by DMA. Also, the onset curing temperature decreases as the amount of IL increase indicating that IL also takes part on the curing process. DSC and FTIR analyses confirm that the imidazolium‐based ionic liquid is able to promote the crosslink of the epoxy pre‐polymer without the presence of external curing agent.

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Exactness of some (0,1)‐forms in Hilbert spaces of infinite dimension
Authors: Talhaoui Abdallah
Published: May 2011

We study the local exactness of the \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\overline{\partial }$\end{document} operator in the Hilbert space l2 for a particular class of (0, 1)‐forms ω of the type \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\omega (z) = \sum _i z_i\omega ^i(z) d\overline{z}_i$\end{document}, z = (zi) in l2. We suppose that each function ωi of class C∞ in the closure of the unit ball of l2, of the form \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\omega ^i(z) = \sum _k \omega ^i_k\left(z^k\right)$\end{document}, where \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\mathbf N = \bigcup I_k$\end{document} is a partition of \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\mathbf N$\end{document} (card Ik < +∞) and zk is the projection of z on \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\mathbf C^{I_k}$\end{document}. We obtain a positive result (Theorem 1.1) when the sequence (card Ik) is bounded. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Thermal analysis of aluminium foam based on micro‐computed tomography
Authors: Veyhl C. , Belova I. V. , Murch G. E. , Öchsner A. , Fiedler T.
Published: May 2011

Finite element analyses are performed in order to determine the effective thermal conductivity of closed‐cell Alporas® foam and open‐cell M‐Pore® sponge. The investigated finite element models are based on high resolution micro‐computed tomography images. The complex structures of the real materials are very well represented with this method. The dependence between the computed effective thermal conductivities and relative density is approximated with analytical scaling laws and linear regression models. Calculations in three perpendicular directions aim towards the investigation of a possible anisotropy. Furthermore, different model sizes are considered in order to estimate the representative volume for the effective thermal conductivity. The findings of this paper indicate that a unit cell containing at least 3 cells in each direction or 27 cells in total is sufficiently large to determine the effective thermal conductivity of these cellular materials. Note that both Alporas® and M‐Pore® exhibit the same qualitative behaviour (i. e. a linearly increasing thermal conductivity with rising relative density) at different absolute levels. More precisely, Alporas® exhibits an approximately two times higher effective thermal conductivity than M‐Pore®.
Structure borne sound in metallic hollow sphere structures
Authors: Winkler R. , Pannert W. , Merkel M. , Öchsner A.
Published: May 2011

Metallic hollow sphere structures (MHSS) form a relatively new group of advanced composite materials characterised by high geometry reproduction leading to stable mechanical and physical properties. The MHSS combine the well‐known advantages of cellular metals in terms of their high ability for energy adsorption, good damping behaviour, excellent heat insulation and high specific stiffness without major scattering of their material parameters. A combination of these properties opens a wide field of potential applications, e. g. in automotive (crash absorber) and aerospace industry (sandwich panels). Various joining technologies such as sintering, soldering and adhering can be used to assemble single metallic hollow spheres to interdependent structures and allow different macroscopic properties. In this study the behaviour of Metallic Hollow Spheres Structures due to structure‐borne sound is investigated. Longitudinal vibrations within a rod serve as an example. Experimental data are compared with analytical solutions and results computed by the finite element method.
On the influence of carbon nanotubes on the wear performance and hardness of aluminium matrix composites
Authors: Xu W. , Ke L. , Xing L. , Zhao X.
Published: May 2011

The friction stir process (FSP) can be used to prepare carbon nanotubes (CNTs) forming reinforced Al matrix composites. The effect of CNTs content on the wear behaviour and hardness of aluminium based composites was studied. Adding CNTs effectively strengthens the matrix, and significantly improves the hardness of the composites. Composite wear test results showed that the addition of CNTs could enhance the wear resistance of the matrix. With increasing CNTs content, the wear resistance of the matrix markedly improved. The wear curve of the materials is a smooth curve.
Effect of reinforcement arrangement on the limit strength capacity of concrete slabs
Authors: Matešan D. , Radnić J. , Grgić N.
Published: May 2011

The paper first presents the results of experimental tests of limit strength capacity of a one‐way reinforced concrete slab with three different reinforcement arrangements and a two‐way reinforced concrete slab with three different support types. A numerical model for the analysis of reinforced concrete and pre‐stressed concrete slabs and shells, already developed by the authors, was additionally tested on the obtained experimental test results. Then, the limit strength capacity of one‐way and two‐way reinforced concrete slabs was tested for different reinforcement arrangements using the aforementioned numerical model. Finally, the main conclusions of the research are presented.
Experiments on the bending failure of diagonally stiffened circular plates
Authors: Modarresi H. , Showkati H.
Published: May 2011

In this paper, the bending behavior of circular steel plates with diagonal stiffeners has been studied. A bending analysis of the circular plates with different diagonal stiffeners has been carried out experimentally in order to predict their ultimate bending capacity. Two types of shallow and deep stiffeners of reverse L and rectangular cross sections were installed to strengthen the plates. In the experiments, both simply‐supported and clamped‐edge boundary conditions were set up under the effect of lateral pressure. The obtained experimental results have been verified by a non‐linear analysis of the stiffened circular plates using the finite element method (FEM). The analytical process has been carried out based on the tensile test data of the steel used in the specimens. Furthermore, the post‐buckling behavior of the plates has been studied up to the final flexural collapse, where unusual rupture results have been found. Different studies have shown a good consistency between experimental and analytical results.
Recovery stresses in SMA wires for civil engineering applications: experimental analysis and thermomechanical modelling
Authors: Tran H. , Balandraud X. , Destrebecq J.‐F.
Published: May 2011

The present study deals with the creation of so‐called “recovery stresses” in SMA wires. Two approaches are developed. First, experiments are performed on nickel‐titanium wires with suitable transformation temperatures. The wires are stretched in the martensite state at ambient temperature. A thermal cycle at constant strain is applied to transform the martensite to austenite, in order to activate the shape memory effect. During the thermal loading, both the phase transformation and the thermal expansion lead to stresses in the wires. Second, a thermomechanical model is used to analyze the experimental results. The model accounts for the phase transformations caused by combinations of stress and temperature loadings. The results are then discussed in the framework of application to concrete component reinforcement.
A one‐dimensional implementation of a coupled elasto‐plastic model for ductile damage
Authors: Esmaeili M. , Öchsner A.
Published: May 2011

A one‐dimensional numerical implementation of the Lemaitre damage model is presented. The implementation is close to classical finite element schemes but can be realised by simple codes or by the application of commercial computer algebra systems. Based on the presented theory and computational algorithm, the elasto‐plastic deformation of a one‐dimensional bar is simulated. The damage evolution is evaluated for different isotropic hardening behaviour and stated as a function of the plastic strain. The described algorithm allows a simple investigation of the influence of different parameters on the damage evolution.
Pardoprunox in early Parkinson's disease: Results from 2 large, randomized double‐blind trials
Authors: Sampaio Cristina , Bronzova Juliana , Hauser Robert A. , Lang Anthony E. , Rascol Olivier , van de Witte Serge V. , Theeuwes and Ad ,   for the Rembrandt/Vermeer Study Groups
Published: May 2011

This report presents the results of 2 randomized trials—Rembrandt and Vermeer—on the efficacy and safety of pardoprunox in patients with early Parkinson's disease. Patients with Parkinson's disease with a Unified Parkinson's Disease Rating Scale–Motor score ≥ 10 and modified Hoehn and Yahr stage ≤ 3 were randomized to pardoprunox (fixed doses of 6 mg/day [n = 115] or 12 mg/day [n = 118] or a flexible‐dose range of 12–42 mg/day [n = 116]) or placebo (n = 119) in Rembrandt and pardoprunox 12–42 mg/day (n = 108), pramipexole 1.5–4.5 mg/day (n = 116), or placebo (n = 110) in Vermeer. Pardoprunox showed a significant benefit over placebo in the primary efficacy variable, least‐square mean change from baseline in Unified Parkinson's Disease Rating Scale–Motor score: Rembrandt—fixed doses of 6 and 12 mg/day, −6.0 and −4.7 points, respectively; flexible‐dose 12–42 mg/day, −5.5 points; placebo, −2.9 points; Vermeer—flexible‐dose 12–42 mg/day, −4.9 points; placebo, −2.5 points; pramipexole, −5.7 points. No minimum effective dose was established. Secondary efficacy parameters supported the results of the primary efficacy variable. Pardoprunox tolerability was dose related: flexible‐dose 12–42 mg/day showed the highest dropout rate due to treatment‐emergent adverse events (Rembrandt, 56.0%; Vermeer, 46.3%) and overall incidence of treatment‐emergent adverse events (Rembrandt, 97.4%; Vermeer, 92.6%), primarily due to nausea, somnolence, and dizziness. Because pardoprunox showed similar efficacy across all dose groups, these observations suggest that the 12–42 mg/day dose range was higher than therapeutically required. Furthermore, the early onset of treatment‐emergent adverse events and dropouts observed for pardoprunox suggest that titration was too rapid. Pardoprunox significantly improved motor symptoms in patients with early Parkinson's disease, but further investigation into the dose and titration schedule is required to improve tolerability. © 2011 Movement Disorder Society
Does cardiovascular autonomic dysfunction contribute to fatigue in Parkinson's disease?
Authors: Nakamura Tomohiko , Hirayama Masaaki , Hara Takashi , Hama Tetsuo , Watanabe Hirohisa , Sobue Gen
Published: May 2011

Patients with Parkinson's disease often complain of fatigue, and although cardiac sympathetic denervation is thought to be associated with fatigue, this link remains unclear. Previously, we detected cardiac sympathetic denervation in patients with Parkinson's disease using dobutamine, a selective beta‐1 stimulant. To clarify the involvement of autonomic dysfunction in fatigue in Parkinson's disease, we conducted autonomic function tests on 33 patients with Parkinson's disease (mean age, 66.1 ± 5.6 years; 20 men, 13 women) and evaluated their relationships to fatigue. We divided patients into 2 groups, fatigued (n = 12) and nonfatigued (n = 21), based on an average score ≥ 3.3 on the Parkinson fatigue scale. Autonomic function tests included the coefficient of variation of R–R intervals, head‐up tilt test, norepinephrine and dobutamine infusion tests, and cardiac 123I‐metaiodobenzylguanidine scintigraphy. The coefficient of variation of R–R intervals and the systolic blood pressure changes accompanying the head‐up tilt test did not show significant differences between the 2 groups; however, the pressor responses in the norepinephrine and dobutamine infusion tests were significantly greater in the fatigued group than in the nonfatigued group. The 123I‐metaiodobenzylguanidine heart‐to‐mediastinal uptake ratio was lower in the fatigued group than in the nonfatigued group. Partial correlation analyses, using disease duration and Hoehn and Yahr stage as control variables, also demonstrated significant correlations between the Parkinson fatigue scale score and the results of the autonomic function tests and cardiac 123I‐metaiodobenzylguanidine uptake. Our results suggest that autonomic dysfunction, including cardiac sympathetic denervation, is associated with fatigue in patients with Parkinson's disease. © 2011 Movement Disorder Society
Isotropic conforming refinement of quadrilateral and hexahedral meshes using two‐refinement templates
Authors: Ebeida Mohamed S. , Patney Anjul , Owens John D. , Mestreau Eric
Published: May 2011

This paper presents three automated algorithms for isotropic, conforming refinement of all‐quadrilateral and all‐hexahedral meshes. These algorithms are based on the two‐refinement templates introduced by Schneiders. However, we introduce a novel technique to choose the appropriate refinement template locally. This enables efficient implementation of the proposed algorithms, even in parallel. The proposed algorithms can handle refined regions of complicated geometry and do not suffer from concavity restrictions associated with the three‐refinement methods currently dominating the literature. Several application examples show the strength of these new algorithms in problems that require fast dynamic remeshing such as computational fluid dynamics and computer graphics. Copyright © 2011 John Wiley & Sons, Ltd.
Mobile and immobile gaseous transport: Embedded analytical solutions to finite volume methods
Authors: Geiser Jürgen
Published: May 2011

The motivation is driven by deposition processes based on chemical vapor problems. The underlying model problem is based on coupled transport–reaction equations with mobile and immobile areas. We deal with systems of ordinary and partial differential equations. Such equation systems are delicate to solve and we introduce a novel solver method, that takes into account ways to solve analytically parts of the transport and reaction equations.

The main idea is to embed the analytical and semianalytical solutions, which can then be explicitly given to standard numerical schemes of higher order.

The numerical scheme is based on flux‐based characteristic methods, which is a finite volume method. Such a method is an attractive alternative to the standard numerical schemes, which fully discretize the full equations. We instead reduce the computational time while embedding fast computable analytical parts.

Here, we can accelerate the solver process, with a priori explicitly given solutions. We will focus on the derivation of the analytical solutions for general and special solutions of the characteristic methods that are embedded into a finite volume method.

In the numerical examples, we illustrate the higher‐order method for different benchmark problems. Finally, the method is verified with realistic results. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2012
Stochastic control of credit default insurance for subprime residential mortgage‐backed securities
Authors: Petersen M. A. , Mulaudzi M. P. , Mukuddem‐Petersen J. , Schoeman I. M. , de Waal B.
Published: May 2011

Subprime residential mortgage securitization and its associated risks have been a major topic of discussion since the onset of the mortgage crisis in July 2007. In this paper, we provide a stochastic dynamic model for investing bank profit under mortgage securitization. In addition, aspects of this model are illustrated by means of a numerical example. In addition, we solve a stochastic optimal credit default insurance problem that has the cash outflow rate for satisfying depositor obligations, the investment in structured mortgage products and credit default insurance as controls. As far as the latter is concerned, we compute credit default swap and accrued premiums by considering the credit rating of structured mortgage products such as residential mortgage‐backed securities and collateralized debt obligations. Copyright © 2011 John Wiley & Sons, Ltd.