bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transport property measurements in tungsten sulphoselenide single crystals grown by a CVT technique
Authors: Solanki G. K. , Gujarathi D. N. , Deshpande M. P. , Lakshminarayana D. , Agarwal M. K. 
Published: November 2007

AbstractThe transport properties of ternary mixed WSxSe2‐x single crystals have been studied by measuring the thermo power, electrical conductivities and Hall parameters in a small temperature range 303‐423 K. The electrical conductivity was highest for selenium rich WSe2 and lowest for sulphur rich WS2 crystals. All the crystals showed semiconducting behaviour from the temperature dependence of ‘ρ’, ‘RH’ and ‘S’. The Hall coefficients showed that the samples are p‐type conducting. The temperature dependence of resistivity, Hall coefficients, carrier concentration showed that all of them are thermally activated. The values of activation energies, pre‐exponential factors and the scattering parameters have been determined. The dominant scattering mechanism for the charge carriers has been explained. The relation between the TEP and the concentration of charge carriers and electrical conductivity was studied. The effective masses of holes and the effective density of states have been determined. These parameters show an increase with increase in sulphur content. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chip‐LC‐MS for label‐free profiling of human serum
Authors: Horvatovich Peter , Govorukhina Natalia I. , Reijmers Theo H. , van der Zee Ate G. J. , Suits Frank , Bischoff Rainer 
Published: November 2007

AbstractThe discovery of biomarkers in easily accessible body fluids such as serum is one of the most challenging topics in proteomics requiring highly efficient separation and detection methodologies. Here, we present the application of a microfluidics‐based LC‐MS system (chip‐LC‐MS) to the label‐free profiling of immunodepleted, trypsin‐digested serum in comparison to conventional capillary LC‐MS (cap‐LC‐MS). Both systems proved to have a repeatability of ∼20% RSD for peak area, all sample preparation steps included, while repeatability of the LC‐MS part by itself was less than 10% RSD for the chip‐LC‐MS system. Importantly, the chip‐LC‐MS system had a two times higher resolution in the LC dimension and resulted in a lower average charge state of the tryptic peptide ions generated in the ESI interface when compared to cap‐LC‐MS while requiring ∼30 times less (∼5 pmol) sample. In order to characterize both systems for their capability to find discriminating peptides in trypsin‐digested serum samples, five out of ten individually prepared, identical sera were spiked with horse heart cytochrome c. A comprehensive data processing methodology was applied including 2‐D smoothing, resolution reduction, peak picking, time alignment, and matching of the individual peak lists to create an aligned peak matrix amenable for statistical analysis. Statistical analysis by supervised classification and variable selection showed that both LC‐MS systems could discriminate the two sample groups. However, the chip‐LC‐MS system allowed to assign 55% of the overall signal to selected peaks against 32% for the cap‐LC‐MS system.
Liquid microjunction surface sampling probe electrospray mass spectrometry for detection of drugs and metabolites in thin tissue sections
Authors: Van Berkel Gary J. , Kertesz Vilmos , Koeplinger Kenneth A. , Vavrek Marissa , Kong Ah‐Ng Tony 
Published: November 2007

AbstractA self‐aspirating, liquid microjunction surface sampling probe/electrospray emitter mass spectrometry system was demonstrated for use in the direct analysis of spotted and dosed drugs and their metabolites in thin tissue sections. Proof‐of‐principle sampling and analysis directly from tissue without the need for sample preparation was demonstrated first by raster scanning a region on a section of rat liver onto which reserpine was spotted. The mass spectral signal from selected reaction monitoring was used to develop a chemical image of the spotted drug on the tissue. The probe was also used to selectively spot sample areas of sagittal whole‐body tissue from a mouse that had been dosed orally (90 mg/kg) with R,S‐sulforaphane 3 h prior to sacrifice. Sulforaphane and its glutathione and N‐acetyl cysteine conjugates were monitored with selected reaction monitoring and detected in the stomach and various other tissues from the dosed mouse. No signal for these species was observed in the tissue from a control mouse. The same dosed‐tissue section was used to illustrate the possibility of obtaining a lane scan across the whole‐body section. In total, these results illustrate the potential for rapid screening of the distribution of drugs and metabolites in thin tissue sections with the liquid micro‐junction surface sampling probe/electrospray mass spectrometry approach. Published in 2007 by John Wiley & Sons, Ltd.
Elucidation of urinary metabolites of fluoxymesterone by liquid chromatography‐tandem mass spectrometry and gas chromatography‐mass spectrometry
Authors: Pozo Oscar J. , Van Thuyne Wim , Deventer Koen , Van Eenoo Peter , Delbeke Frans T. 
Published: November 2007

AbstractThe suitability of liquid chromatography tandem mass spectrometry (LC‐MS/MS) and gas chromatography mass spectrometry (GC‐MS) for the elucidation of fluoxymesterone metabolism has been evaluated. Electrospray ionization (ESI) and collision induced dissociation (CID) fragmentation in LC‐MS/MS and electron impact spectra (EI) in GC‐MS have been studied for fluoxymesterone and two commercially available metabolites. MSn experiments and accurate mass measurements performed by an ion‐trap analyser and a QTOF instrument respectively have been used for the elucidation of the fragmentation pathway. The neutral loss scan of 20 Da (loss of HF) in LC‐MS/MS has been applied for the selective detection of fluoxymesterone metabolites. In a positive fluoxymesterone doping control sample, 9 different analytes have been detected including the parent compound. Seven of these metabolites were also confirmed by GC‐MS including 5 previously unreported metabolites. On the basis of the ionization, the CID fragmentation, the accurate mass of the product ions and the EI spectra of these analytes, a tentative elucidation as well as a proposal for the metabolic pathway of fluoxymesterone has been suggested. The presence of these compounds has also been confirmed by the analysis of five other positive fluoxymesterone urine samples. Copyright © 2007 John Wiley & Sons, Ltd.
Discrimination and identification of the six aromatic positional isomers of trimethoxyamphetamine (TMA) by gas chromatography‐mass spectrometry (GC‐MS)
Authors: Zaitsu Kei , Katagi Munehiro , Kamata Hiroe , Kamata Tooru , Shima Noriaki , Miki Akihiro , Iwamura Tatsunori , Tsuchihashi Hitoshi 
Published: November 2007

AbstractA reliable and accurate GC‐MS method was developed that allows both mass spectrometric and chromatographic discrimination of the six aromatic positional isomers of trimethoxyamphetamine (TMA). Regardless of the trifluoroacetyl (TFA) derivatization, chromatographic separation of all the investigated isomers was achieved by using DB‐5ms capillary columns (30 m × 0.32 mm i.d.), with run times less than 15 min. However, the mass spectra of the nonderivatized TMAs, except 2,4,6‐trimethoxyamphetmine (TMA‐6), showed insufficient difference for unambiguous discrimination. On the other hand, the mass spectra of the TFA derivatives of the six isomers exhibited fragments with significant intensity differences, which allowed the unequivocal identification of all the aromatic positional isomers investigated in the present study. This GC‐MS technique in combination with TFA derivatization, therefore, is a powerful method to discriminate these isomers, especially useful to distinguish the currently controlled 3,4,5‐trimethoxyamphetmine (TMA‐1) and 2,4,5‐trimethoxyamphetmine (TMA‐2) from other uncontrolled TMAs. Copyright © 2007 John Wiley & Sons, Ltd.
Poly(γ‐glutamic acid) nanoparticles as an efficient antigen delivery and adjuvant system: Potential for an AIDS vaccine
Authors: Wang Xin , Uto Tomofumi , Akagi Takami , Akashi Mitsuru , Baba Masanori 
Published: November 2007

AbstractAntigen delivery systems using polymeric nanoparticles are of special interest as stable protein‐based antigen carriers. In the present study, novel biodegradable poly(γ‐glutamic acid) (γ‐PGA) nanoparticles were examined for their antigen delivery and immunostimulatory activities in vitro and in vivo. The uptake of ovalbumin by dendritic cells was markedly enhanced by γ‐PGA nanoparticles, and the ovalbumin was gradually released from γ‐PGA nanoparticles into the cells. In addition, γ‐PGA nanoparticles appeared to have great potential as an adjuvant, because they could induce the maturation of dendritic cells. Although not only ovalbumin‐encapsulating nanoparticles (OVA‐NPs) but also a simple mixture of ovalbumin and nanoparticles induced dendritic cell maturation, the only dendritic cells exposed to OVA‐NPs could strongly activate antigen‐specific interferon (IFN)‐γ‐producing T cells. Subcutaneous immunization of mice with human immunodeficiency virus type 1 (HIV‐1) p24‐encapsulating nanoparticles activated antigen‐specific IFN‐γ‐producing T cells in spleen cells and induced p24‐specific serum antibodies, as compared to immunization with p24 alone. Like ovalbumin, a mixture of p24 and nanoparticles also induced antigen‐specific serum antibodies but did not activate IFN‐γ‐producing T cells in spleen cells, suggesting that nanoparticles play a critical role in inducing cellular immune responses. Furthermore, γ‐PGA nanoparticles had a capacity comparable to that of the complete Freund's adjuvant (CFA) in inducing p24‐specific serum antibody. However, unlike CFA, they predominantly activated p24‐specific IFN‐γ‐producing T cells. Thus, γ‐PGA nanoparticles encapsulating various antigens may have great potential as novel and efficient protein‐based vaccines against infectious diseases, including HIV‐1 infection. J. Med. Virol. 80:11–19, 2008. © 2007 Wiley‐Liss, Inc.
Development of a TaqMan assay for the six major genotypes of hepatitis C virus: Comparison with commercial assays
Authors: Engle Ronald E. , Russell Rodney S. , Purcell Robert H. , Bukh Jens 
Published: November 2007

AbstractA quantitative real‐time PCR assay was developed that detects genomic RNA from reference strains representing the six major genotypes of hepatitis C virus (HCV) with equal sensitivity and accurately measured HCV RNA in JFH1 HCV‐infected Huh7.5 cells. The method is indirectly calibrated to the first international (WHO 96/790) HCV standard preparation and has a linear dynamic range of 102.6–106.5 IU/ml. In addition, the inter‐ and intra‐assay precision were ∼3% CV and <2% CV, respectively. Comparison with results obtained by commercially available HCV RNA Nucleic Acid Technology kits (Versant HCV RNA 3.0 b‐DNA and Amplicor HCV Monitor), that also employ the WHO standard, allowed validation of the TaqMan assay against all major HCV genotypes. Both commercial methods detected HCV RNA over a wide dynamic range, but showed a consistent difference of about 0.3 log10 when evaluating samples of different HCV genotypes. The genome titers obtained with the three methods correlated with the infectivity titers previously determined for the HCV reference strains. TaqMan assays have become an essential tool to follow viral load in clinical samples and cell culture‐based experiments and this technology offers significant advantages in linear dynamic range, sensitivity and customization. J. Med. Virol. 80:72–79, 2008. © 2007 Wiley‐Liss, Inc.
Toxicological evaluation of transgenic rice flour with an Escherichia coli phytase gene appA by sub‐chronic feeding study in Wistar rats
Authors: Tsai Cheng‐Chih , Lai Chieh‐Hsien , Yang Chi‐Sheng , Lin Chien‐Ku , Tsen Hau‐Yang 
Published: November 2007

AbstractBACKGROUND: Phytase is increasingly used as an ingredient in swine and poultry feeds to improve the bioavailability of phytate‐bound phosphorus and reduce the supplement of elemental phosphorus in feeds. Recently, a transgenic rise (TGR) with phytase appA gene from E. coli has been developed in Taiwan. To assure the food safety of this TGR, we performed a sub‐chronic whole‐food feeding study with Wistar rats.RESULTS: Weaned feeding male and female rats were divided into TGR and non‐TGR (NTGR) groups (20 rats per group), and fed diets containing 76.8% rice flour of TGR and NTGR, respectively. After 93 days feeding, although some hematological findings and blood chemistry values differed significantly between the TGR and NTGR groups, all values were still within the normal range for rats of this age and sex. No adverse effects of TGR were observed in terms of animal behavior, weight gain, or feed utilization rate. Necropsy at the end of the experiment indicated that neither pathological lesions nor histopathological abnormalities were present in organs such as liver, kidney, intestines and testes of rats in TGR and NTGR groups. In addition, no significant differences (P > 0.05) were observed in relative organ weights, hemograms and blood indices of rats between the two groups.CONCLUSION: These results demonstrated that in a 93‐day feeding study with Wistar rats a diet containing 76.8% of TGR flour having a phytase activity of about 1500 U kg−1 body weight per day has no adverse effects. Copyright © 2007 Society of Chemical Industry
Solid substrate bioassay to evaluate impact of Trichoderma on trichothecene mycotoxin production by Fusarium species
Authors: Busko Maciej , Chełkowski Jerzy , Popiel Delfina , Perkowski Juliusz 
Published: November 2007

AbstractBACKGROUND: Fusarium head blight of wheat is a destructive disease in various wheat‐growing regions and leads to significant yield losses for farmers and to contamination of cereal grains with mycotoxins, mainly deoxynivalenol and its derivatives. Toxigenic Fusarium species sporulate on cereal crop residues and produce significant inoculum for epidemics. Reduction of mycotoxin production and pathogen sporulation may be influenced by saprophytic fungal antagonists.RESULTS: Trichoderma isolates were examined in dual culture bioassays on rice with two isolates of Fusarium graminearum Schwabe and two isolates of Fusarium culmorum (W.G. Smith) Saccardo, belonging to three different chemotypes. Production of five trichothecene mycotoxins, deoxynivalenol (DON), 3‐acetyl‐deoxynivalenol (3AcDON), 15‐acetyl‐deoxynivalenol (15AcDON), nivalenol (NIV) and fusarenone X (FUS), was reduced by over 95%. Two Trichoderma isolates partially reduced the amounts of four metabolites when inoculated on autoclaved cultures of the same four Fusarium isolates. However, in the case of the 15AcDON chemotype of F. culmorum culture the content of DON increased and that of 15AcDON decreased. Isolates of Trichoderma varied in their ability to inhibit production of the five trichothecene mycotoxins by Fusarium. Susceptibility of the four Fusarium isolates to antagonistic activity of the same Trichoderma isolate differed significantly.CONCLUSION: Selected non‐toxigenic Trichoderma isolates proved to be useful biocontrol agents against toxigenic Fusarium pathogens of wheat, significantly reducing production of the trichothecene mycotoxins DON, NIV and their acetylated derivatives. Copyright © 2007 Society of Chemical Industry
Determination of pesticides in water samples by solid phase extraction and gas chromatography tandem mass spectrometry
Authors: Ruiz‐Gil Laura , Romero‐González Roberto , Garrido Frenich Antonia , Martínez Vidal José L. 
Published: November 2007

AbstractA multiresidue method for the determination of more than 80 pesticides in water has been developed and validated. The proposed method is based on SPE followed by GC coupled to MS/MS. Different variables affecting SPE procedure, such as cartridges, sample volume and solvents were studied, and mass spectrometric conditions were optimised in order to increase selectivity and sensitivity. Calibration curves were linear over the range of 0.03–0.5 μg/L. Recoveries were in the range of 70–110% and repeatability was below 20% for the lowest calibration point. LODs ranged from 0.001 to 0.025 μg/L and LOQs from 0.003 to 0.076 μg/L. Finally, the method was successfully applied to the analysis of water samples from southeast of Spain.
Trust and formal contracts in interorganizational relationships — substitutes and complements
Authors: Mellewigt Thomas , Madhok Anoop , Weibel Antoinette 
Published: November 2007

AbstractWe hypothesize that trust is a moderator of the direct relationship between control and coordination concerns and contractual complexity. Our results suggest that high trust weakens the positive relationship between control concerns and contractual complexity and reinforces the positive relationship between coordination concerns and contractual complexity. By highlighting the dual role of contracts (i.e. a controlling and coordinating function) and the moderating role of trust in this regard, our paper provides a new focus to the current discussion on the relationship between trust and contracts (i.e. substitutes or complements) that may help reconcile some divergent perspectives in the literature. Copyright © 2007 John Wiley & Sons, Ltd.
Slower conduction velocity and motor unit discharge frequency are associated with muscle fatigue during isometric exercise in type 1 diabetes mellitus
Authors: Almeida S. , Riddell M.C. , Cafarelli E. 
Published: November 2007

AbstractType 1 diabetes mellitus (T1DM) is associated with a peripheral neuropathy that reduces nerve conduction velocity. This may impair high motor‐unit discharge frequencies (MUDF), decrease muscle activation, and curtail the ability to sustain repetitive contractile tasks. We examined (1) whether MUDF, the contractile properties of the knee extensors, and the conduction velocity of persons with T1DM differed from controls; (2) whether persons with T1DM can maintain adequate MUDF during a fatigue protocol; and (3) the relationship between these parameters and impaired glycemic control. We studied male and female subjects with T1DM and controls matched for age, height, weight, and gender. Single motor unit recordings were made from vastus lateralis during maximal and submaximal contractions and during a fatigue protocol. Glycemic control was assessed from blood glucose concentration and glycosylated hemoglobin (HbA1c). Control femoral conduction velocities were comparable to literature values and those of the T1DM subjects were slower. These values correlated with plasma glucose and HbA1c. T1DM subjects fatigued 45% sooner than controls, and time to fatigue and conduction velocity were correlated (r = 0.54, P < 0.05). Discharge frequencies tended to be slower during 50% maximal voluntary contractile force in the T1DM subjects at task failure. Persons with T1DM had slower conduction velocities and lower MUDF than their controls, which apparently leads to impaired activation of muscle and decreased endurance during isometric fatigue. Muscle Nerve, 2007
Metformin and glitazones: does similarity in biomolecular mechanism originate from tautomerism in these drugs?
Authors: Sundriyal Sandeep , Khanna Smriti , Saha Rikta , Bharatam Prasad V. 
Published: November 2007

AbstractThis theoretical study attempts to find out similarity between metformin and glitazone class of antidiabetic drugs. It was found that some tautomeric forms of both metformin and thiazolidinedione ring of glitazones have similar molecular electrostatic potential (MESP) surface and may bind to a common complementary surface. Complexation and docking studies were also carried out in order to support this hypothesis. Copyright © 2007 John Wiley & Sons, Ltd.
Improved isotope ratio measurement performance in liquid chromatography/isotope ratio mass spectrometry by removing excess oxygen
Authors: Hettmann Elena , Brand Willi A. , Gleixner Gerd 
Published: November 2007

AbstractA low dead volume oxygen scrubbing system was introduced in a commercially available liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) interface to enhance the analytical capability of the system. In the LC/IRMS interface carbon from organic samples is converted into CO2 inside the mobile phase by wet chemical oxidation using peroxodisulfate (Na2S2O8). After passing the hot reaction zone, surplus oxygen (O2) remains dissolved in the liquid phase. Both CO2 and O2 diffuse through a transfer membrane into the helium carrier and are transferred to the mass spectrometer. The presence of O2 in the ion source may have detrimental effects on measurement accuracy and precision as well as on filament lifetime. As a remedy, a new on‐line O2‐removing device has been incorporated into the system.The new O2 scrubber consists of two parallel hot copper reduction reactors (0.8 mm i.d., active length 120 mm) and a switch‐over valve between them. One reactor is regenerated using He/H2 while the other is actively scavenging O2 from the gas stream. The capacity of each reduction reactor, expressed as usage time, is between 40 and 50 min. This is sufficient for a single LC run for sugars and organic acids. A further increase of the reduction capacity is accompanied by a peak broadening of about 100%. After switching to a freshly reduced reactor the oxygen background and the δ13C values of the reference gas need up to 500 s to stabilize. For repeated injections the δ13C values of sucrose remain constant (±0.1‰) for about 3000 s. The long‐term stability for measurements of sucrose was 0.11‰ without the reduction oven and improved slightly to 0.08‰ with the reduction oven. The filament lifetime improved by more than 600%, thereby improving the long‐term system stability and analytical efficiency. In addition the costs per analysis were reduced considerably. Copyright © 2007 John Wiley & Sons, Ltd.
Characterisation of spherical silicas obtained from sodium silicate and hydrochloric acid in emulsion medium using hexane as the organic phase
Authors: Jesionowski Teofil , Tepper Beata , Krysztafkiewicz Andrzej 
Published: November 2007

AbstractThe process of silica formation in an emulsion medium with hexane as the organic phase has been studied. The precipitation reaction has been conducted with sodium silicate. The conditions of precipitation have been optimised and their effect on the physicochemical properties of the products obtained has been analysed. The products have been synthetic silicas of spherical particle shapes with a number of them revealing high activity. It has been established that by controlling the amount of non‐ionic surfactants used as emulsifiers in the emulsions prepared, it is possible to obtain homogeneous silicas showing poor tendency towards agglomerate and aggregate formation. In particular, greater amounts of surfactants lead to changes in the diameter of the silica particles and increase their tendency to agglomerate formation evidenced by the particle size distributions (PSDs) or SEM and transmission electron microscope (TEM) evaluations. The silica agglomeration promotes sedimentation of their particles in water. The surface of the active silicas produced shows limited hydrophilic properties which is evidenced by the character of their wettability curves. Copyright © 2007 John Wiley & Sons, Ltd.