bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid‐resolution liquid chromatography/mass spectrometry for determination and quantitation of polyphenols in grape berries
Authors: Cavaliere Chiara , Foglia Patrizia , Gubbiotti Riccardo , Sacchetti Paolo , Samperi Roberto , Laganà Aldo 
Published: September 2008

AbstractA rapid‐resolution liquid chromatography/mass spectrometric (RRLC/MS) method for detection and quantitation of polyphenols in grape berry skins and seeds has been developed. Pulp‐free berry skins were treated with liquid nitrogen and ground; seeds were also ground. Then, 3 g of samples were extracted with 30 mL of a mixture of methanol/water/formic acid 70:30:1 (v/v/v) under sonication and 1 µL of the final extract was injected into two 100 × 2.1 mm i.d., 1.8 µm Zorbax Eclipse plus C18 columns connected in series. Compounds were fractionated using a gradient elution of acidified acetonitrile/methanol 50:50 (v/v)/water. Columns were thermostatted at 70°C. MS was carried out on an Agilent 6410 QqQ instrument equipped with an electrospray ionization source. Positive and negative MS/MS product ion scans were used for compound identification, whereas positive full scan MS in the m/z range 200–1400 was used for quantitation. By means of mass spectra comparison, various flavonols, flavan‐3‐ols, anthocyanins and stilbenes were identified. Quantitation was performed by external calibration, and concentration values were corrected for matrix effect that was evaluated in separate experiments. Semi‐quantitative estimation was performed for compounds for which standards were not commercially available. Recoveries ranged from 90–102% with relative standard deviation (RSD) <5%, whereas the between samples RSD was in the range 4–12%. Two surrogate standards were used for quality control. The developed method was applied to analyze the polyphenol content of three Vitis vinifera table cultivars at physiological maturity and after proper preservation for 6 weeks. Results demonstrated that during preservation about half of the polyphenol content was lost. Copyright © 2008 John Wiley & Sons, Ltd.
A gas chromatography/combustion/isotope ratio mass spectrometry system for high‐precision δ13C measurements of atmospheric methane extracted from ice core samples
Authors: Behrens Melanie , Schmitt Jochen , Richter Klaus‐Uwe , Bock Michael , Richter Ulrike C. , Levin Ingeborg , Fischer Hubertus 
Published: September 2008

AbstractPast atmospheric composition can be reconstructed by the analysis of air enclosures in polar ice cores which archive ancient air in decadal to centennial resolution. Due to the different carbon isotopic signatures of different methane sources high‐precision measurements of δ13CH4 in ice cores provide clues about the global methane cycle in the past. We developed a highly automated (continuous‐flow) gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) technique for ice core samples of ∼200 g. The methane is melt‐extracted using a purge‐and‐trap method, then separated from the main air constituents, combusted and measured as CO2 by a conventional isotope ratio mass spectrometer. One CO2 working standard, one CH4 and two air reference gases are used to identify potential sources of isotope fractionation within the entire sample preparation process and to enhance the stability, reproducibility and accuracy of the measurement. After correction for gravitational fractionation, pre‐industrial air samples from Greenland ice (1831 ± 40 years) show a δ13CVPDB of −49.54 ± 0.13‰ and Antarctic samples (1530 ± 25 years) show a δ13CVPDB of −48.00 ± 0.12‰ in good agreement with published data. Copyright © 2008 John Wiley & Sons, Ltd.
Structural modifications of serum transthyretin in rats during protein‐energy malnutrition
Authors: Henze Andrea , Rohn Sascha , Gericke Beate , Raila Jens , Schweigert Florian J. 
Published: September 2008

AbstractTransthyretin (TTR) is a sensitive marker of protein‐energy malnutrition and changes in serum and expression levels during protein and energy deficiency are well described. However, little is known about structural modifications of TTR during protein and/or energy deprivation. Therefore, the aim of this study was to determine the effects of protein inadequacies on post‐translational modifications of TTR. For this purpose, male Wistar rats were fed a diet with either casein or gelatine as sole protein source subsequent to a protein wash‐out period. Changes in TTR serum levels as well as other markers of nutritional status as body weight, food consumption, total serum protein and serum RBP4 levels as well as antioxidative capacity were determined. Post‐translational modifications of TTR were examined by matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOFMS) analysis. The rats from the gelatine group revealed a marked change in the post‐translational modification pattern of TTR which was reflected by a significant elevation of sulfonated TTR and which was inversely correlated to the antioxidative capacity. Additionally, the elevation of sulfonated TTR was accompanied by a decrease in body weight and food consumption, low antioxidative capacity as well as a deprivation of serum TTR, RBP4 and total serum protein levels in the animals of the gelatine group. Protein‐energy malnutrition leads therefore next to changes in TTR serum concentration, also to changes in the post‐translational modification pattern of TTR. Such changes are probably induced by protein‐energy malnutrition‐driven oxidative stress and might be linked to alterations in protein function and stability. Copyright © 2008 John Wiley & Sons, Ltd.
Development of a validated liquid chromatography/tandem mass spectrometry method for the distinction of thyronine and thyronamine constitutional isomers and for the identification of new deiodinase substrates
Authors: Piehl Susanne , Heberer Thomas , Balizs Gabor , Scanlan Thomas S. , Köhrle Josef 
Published: September 2008

AbstractThyronines (THs) and thyronamines (TAMs) are two groups of endogenous iodine‐containing signaling molecules whose representatives differ from each other only regarding the number and/or the position of the iodine atoms. Both groups of compounds are substrates of three deiodinase isozymes, which catalyze the sequential reductive removal of iodine from the respective precursor molecule. In this study, a novel analytical method applying liquid chromatography/tandem mass spectrometry (LC‐MS/MS) was developed. This method permitted the unequivocal, simultaneous identification and quantification of all THs and TAMs in the same biological sample. Furthermore, a liquid‐liquid extraction procedure permitting the concurrent isolation of all THs and TAMs from biological matrices, namely deiodinase (Dio) reaction mixtures, was established. Method validation experiments with extracted TH and TAM analytes demonstrated that the method was selective, devoid of matrix effects, sensitive, linear over a wide range of analyte concentrations and robust in terms of reproducible recoveries, process efficiencies as well as intra‐assay and inter‐assay stability parameters. The method was applied to study the deiodination reactions of iodinated THs catalyzed by the three deiodinase isozymes. With the HPLC protocol developed herein, sufficient chromatographic separation of all constitutional TH and TAM isomers was achieved. Accordingly, the position of each iodine atom removed from a TH substrate in a Dio‐catalyzed reaction was backtracked unequivocally. While several established deiodination reactions were verified, two as yet unknown reactions, namely the phenolic ring deiodination of 3′,5′‐diiodothyronine (3′,5′‐T2) by Dio2 and the tyrosyl ring deiodination of 3‐monoiodothyronine (3‐T1) by Dio3, were newly identified. Copyright © 2008 John Wiley & Sons, Ltd.
A high‐resolution scanning microprobe matrix‐assisted laser desorption/ionization ion source for imaging analysis on an ion trap/Fourier transform ion cyclotron resonance mass spectrometer
Authors: Koestler Martin , Kirsch Dieter , Hester Alfons , Leisner Arne , Guenther Sabine , Spengler Bernhard 
Published: September 2008

AbstractA new scanning microprobe matrix‐assisted laser desorption/ionization (SMALDI) ion source for high spatial resolution has been developed for linear ion trap and Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS). The source is fully compatible with commercial ion trap flanges (such as the LTQ series, Thermo Fisher Scientific). The source is designed for atmospheric pressure (AP) operation but is also suitable for mid‐pressure operation. The AP mode is especially useful for investigating volatile compounds. The source can be interchanged with other ion sources within a minute when operated in the AP mode. Combining high‐lateral resolution MALDI imaging with high mass resolution and high mass accuracy mass spectrometry, available in the FT‐ICR mode, provides a new quality of analytical information, e.g. from biological samples. First results obtained with the new ion source demonstrate a maximum lateral resolution of 0.6 by 0.5 µm. Depending on the limit of detection of the chosen mass analyzer, however, the size of the focus had to be enlarged to a diameter of up to 8 µm in the FT‐ICR mode, in order to create enough ions for detection. Mass spectra acquired for analytical imaging were obtained from single laser pulses per pixel in all the experiments. This mode allows us to investigate biological thin sections with desorption focus diameters in the micrometer range, known to cause complete evaporation of material under the laser focus with a very limited number of laser pulses. As a first example, peptide samples deposited in microstructures were investigated with the new setup. A high quality and validity of the acquired images were obtained in the ion trap mode due to the low limit of detection. High mass resolution and accuracy but poorer image quality were obtained in the ICR mode due to the lower detection sensitivity of the ICR detector. Copyright © 2008 John Wiley & Sons, Ltd.
Securing reactive routing protocols in MANETs using PKI (PKI‐DSR)
Authors: Kadri Benamar , Feham Mohammed , M'hamed Abdallah 
Published: September 2008

AbstractMobile Ad hoc Networks (MANETs) are deployed in many new domestic and public applications, contributing to new requirements in terms of performance and efficiency. However due to their nature, some usual network services such as routing and security are not carried out as well as expected. Securing routing protocols is one of these challenging tasks, since security is not natively implemented in ad hoc routing, and the extensions given in the literature are complex and vulnerable against several attacks. Therefore in this paper, we propose an implementation of public key infrastructure (PKI) exploiting the route discovery and route reply mechanisms of reactive routing protocols to publish self‐issued certificates in a distributed fashion. These certificates are used by mobile nodes to secure communications, ensure authentication, integrity, confidentiality, and detect attacks in mobile ad hoc networks. Our proposed scheme is simple and utilizes the underlying protocol as a support for certificate publishing; therefore it does not affect the performance of the network. In addition, all the operations in our scheme are performed in the network layer making it useful for heterogeneous networks since it has no additional relation with other network layers such as MAC and PHY. Copyright © 2008 John Wiley & Sons, Ltd.
Epitaxial Integration of Nanowires in Microsystems by Local Micrometer‐Scale Vapor‐Phase Epitaxy
Authors: Mølhave Kristian , Wacaser Brent A. , Petersen Dirch Hjorth , Wagner Jakob B. , Samuelson Lars , Bøggild Peter 
Published: September 2008

AbstractFree‐standing epitaxially grown nanowires provide a controlled growth system and an optimal interface to the underlying substrate for advanced optical, electrical, and mechanical nanowire device connections. Nanowires can be grown by vapor‐phase epitaxy (VPE) methods such as chemical vapor deposition (CVD) or metal organic VPE (MOVPE). However, VPE of semiconducting nanowires is not compatible with several microfabrication processes due to the high synthesis temperatures and issues such as cross‐contamination interfering with the intended microsystem or the VPE process. By selectively heating a small microfabricated heater, growth of nanowires can be achieved locally without heating the entire microsystem, thereby reducing the compatibility problems. The first demonstration of epitaxial growth of silicon nanowires by this method is presented and shows that the microsystem can be used for rapid optimization of VPE conditions. The important issue of the cross‐contamination of other parts of the microsystem caused by the local growth of nanowires is also investigated by growth of GaN near previously grown silicon nanowires. The design of the cantilever heaters makes it possible to study the grown nanowires with a transmission electron microscope without sample preparation.
A Novel Flow‐Cytometry‐Based Assay for Cellular Uptake Studies of Polyelectrolyte Microcapsules
Authors: Semmling Maximilian , Kreft Oliver , Muñoz Javier Almudena , Sukhorukov Gleb B. , Käs Josef , Parak Wolfgang J. 
Published: September 2008

AbstractA flow‐cytometry‐based assay is presented with which the uptake of polyelectrolyte capsules can be quantified. The cavity of the capsules is loaded with the pH‐sensitive dye SNARF, which emits in the red and green in alkaline and acidic environments, respectively. By recording the fluorescence intensities in the red and green channels, the localization of capsules associated with cells can be determined. Capsules adherent to the outer cell membrane fluoresce in the red due to the alkaline pH of the cell medium, whereas capsules internalized by cells fluoresce in the green due to the acidic pH in the endosomal/lysosomal/phagosomal compartments in which incorporated capsules are located. Adding the SNARF readout to the scattering signal typically derived with flow cytometry analysis allows for a more detailed quantitative analysis of particle uptake, which can also distinguish between adherent and ingested particles.
A Polydiacetylene Microchip Based on a Biotin–Streptavidin Interaction for the Diagnosis of Pathogen Infections
Authors: Jung Yun Kyung , Kim Tae Won , Jung Cheulhee , Cho Dae‐Yeon , Park Hyun Gyu 
Published: September 2008

AbstractA micropatterned polydiacetylene (PDA) chip, utilizing the unique fluorogenic property of PDA and a specific biotin–streptavidin (STA) interaction, is constructed to detect pathogen infections. To construct the PDA chip, biotin‐modified diacetylene liposomes are immobilized on aldehyde glass and conjugated with STA, followed by UV irradiation to polymerize the STA‐functionalized diacetylene liposomes. Genomic DNA of a model pathogen, Chlamydia trachomatis, is isolated from human samples and biotin‐labeled target DNA is obtained through PCR amplification using biotin‐11‐dUTP. Owing to the stimulus caused by the biotin–STA interaction, the biotinylated DNA induces an intense fluorescence signal on the immobilized PDA. By using this strategy, it is possible to diagnose Chlamydia infections by applying DNA samples from several nonhealthy humans to a single PDA chip. The results of this study serve as the basis for a new strategy for fluorogenic PDA microarray‐based diagnosis of pathogen infections.
Lysosomal membrane response of earthworm, Eisenia fetida, to arsenic contamination in soils
Authors: Lee Byung‐Tae , Kim Kyoung‐Woong 
Published: September 2008

AbstractEarthworm (Eisenia fetida) were exposed to sandy soils contaminated with arsenate (0.01–0.3 μmol g−1) for 28 days. Lysosomal membrane stability was used as a biomarker to determine the applicability of neutral‐red retention times (NRRTs) for arsenic (As) toxicity to earthworm in soils. Total As and As speciation were analyzed to evaluate dose–response relationship between As accumulation and NRRTs and to observe the role of As metabolism in earthworms on a subcellular level toxicity. Significant decrease of NRRTs was found with the increasing As concentration in soils (ANOVA, P < 0.05). Adverse effects on earthworm survival and growth did not occur when exposed to 0.1 and 0.05 μmol g−1 at 14 and 28 days, respectively, whereas NRRTs showed significant reduction from the control, as was readily bioconcentrated in the reduced form of As(III) in earthworms and clear dose–response relationships were found for As body burden and NRRTs. Therefore, it is possible to conclude that As has an adverse effect on lysosomal membrane of coelomocytes, and NRRT assay is a potentially applicable method to assess As toxicity as an early warning tool. Also, sequestered As in the form of As(III)‐thiol complex can be expected to cause an adverse effect on lysosomal membrane stability. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.
Synthesis and Characterization of an Enantiomerically Pure Lutetium Benzyl Complex
Authors: Meyer Nils , Roesky Peter W. 
Published: September 2008

AbstractThe synthesis and the single‐crystal X‐ray structure of the enantiopure ligand (S,S)‐H2{(iPrATI)2diph} are reported. Reaction of (S,S)‐H2{(iPrATI)2diph} with the lutetium benzyl complex [Lu(CH2Ph)3(THF)3] resulted in the mono benzyl complex [(S,S)‐{(iPrATI)2diph}Lu(CH2Ph)(THF)], which is the first chiral benzyl compound of the lanthanides.
BaN3Cl: Synthese, Kristallstruktur, Schwingungsspektren und thermischer Abbau von Barium‐Azid‐Chlorid
Authors: Blaschkowski Björn , Balzer Harald , Keller Hans‐Lothar , Schleid Thomas 
Published: September 2008

AbstractBaN3Cl: Synthesis, Crystal Structure, Vibrational Spectra and Thermal Decomposition of Barium Azide ChlorideBaN3Cl was yielded as colourless, lath‐shaped and oftenly intergrown single crystals from concentrated aqueous solutions of equimolar quantities of BaCl2 and NaN3. This first example of a ternary metal(II) azide chloride crystallizes monoclinically in space group P 21/m (no. 11) with the lattice constants a = 557.46(5) pm, b = 452.07(4) pm, c = 780.81(7) pm and β = 101.835(6)° (Z = 2). Its crystal structure contains Ba2+ cations in a ninefold monocapped tetragonal antiprismatic environment of five triatomic azide dumbbells (N3−) together with four chloride anions. The Cl− anions themselves are surrounded by four Ba2+ cations tetrahedrally (d(Cl–Ba) = 311–316 pm), whereas N3− shows a fivefold distorted pyramidal Ba2+ coordination (d(N–Ba) = 295–297 pm). The participating ions are stacked in layers along the c‐axis forming cationic $^{2}_{\infty}\rm \{[ClBa_{4/4}]^{+}\}$ sheets of which every rectangular face of four Ba2+ cations is capped with one N3− dumbbell. This arrangement of the involved ions corresponds to a monoclinically distorted variation of the matlockite‐type structure of PbFCl and is therefore viewed as homeotypic. The azide dumbbell in barium azide chloride is strictly linear (∢(N–N–N) = 179.9(6)° and exhibits N–N bond lengths of 117 – 118 pm. The infrared and Raman spectra show vibration frequencies typical for a slightly asymmetric N3− unit (i. e. νas = 2070 cm−1, νs = 1352 cm−1 and δ = 644/634 cm−1). Thermal analyses revealed BaN3Cl to be stable up to 230 °C, before it decomposes to an amorphous solid under evolution of elemental nitrogen (N2).
Formation of Calcium Carbonate Superstructures by Rapid Temperature Change
Authors: Nebel H. , Epple M. 
Published: September 2008

AbstractCalcium carbonate was crystallized in a tubular reactor with crystallization times of the order of seconds from aqueous solutions of calcium chloride and sodium carbonate without additives. By a rapid temperature change during this time, both the morphology and the phase composition (calcite, aragonite, vaterite) changed dramatically. Superstructures consisting of smaller nanoparticles and recrystallization phenomena that otherwise require the presence of additives were formed.
Asymptotic solution for a micropolar flow in a curvilinear channel
Authors: Dupuy D. , Panasenko G.P. , Stavre R. 
Published: September 2008

AbstractThis paper is concerned with an asymptotic approach for a micropolar flow through a thin curvilinear channel. A priori estimates (which we obtain together with the existence and the uniqueness of the solution) are used to establish the error between the exact solution and the asymptotic one and to justify the asymptotic analysis. We obtain the expression of an expansion of order K and we study the general problems for the boundary layer functions. Under some additional assumptions on the data we obtain satisfactory error estimates.
A numerical method with properties of consistency in the energy domain for a class of dissipative nonlinear wave equations with applications to a Dirichlet boundary‐value problem
Authors: Macías‐Díaz J.E. , Puri A. 
Published: September 2008

AbstractIn this work, we present a conditionally stable finite‐difference scheme that consistently approximates the solution of a general class of (3+1)‐dimensional nonlinear equations that generalizes in various ways the quantitative model governing discrete arrays consisting of coupled harmonic oscillators. Associated with this method, there exists a discrete scheme of energy that consistently approximates its continuous counterpart. The method has the properties that the associated rate of change of the discrete energy consistently approximates its continuous counterpart, and it approximates both a fully continuous medium and a spatially discretized system. Conditional stability of the numerical technique is established, and applications are provided to the existence of the process of nonlinear supratransmission in generalized Klein‐Gordon systems and the propagation of binary signals in semi‐unbounded, three‐dimensional arrays of harmonic oscillators coupled through springs and perturbed harmonically at the boundaries, where the basic model is a modified sine‐Gordon equation; our results show that a perfect transmission is achieved via the modulation of the driving amplitude at the boundary. Additionally, we present an example of a nonlinear system with a forbidden band‐gap which does not present supratransmission, thus establishing that the existence of a forbidden band‐gap in the linear dispersion relation of a nonlinear system is not a sufficient condition for the system to present supratransmission.
Dimensional analysis of a model problem in thermoelasto‐plasticity for cylindrical bodies under heating and cooling
Authors: Wolff M. , Böhm M. , Frerichs F. 
Published: September 2008

AbstractWe perform a dimension analysis for a model problem in thermoelasto‐plasticity for (hollow) cylindrical bodies, focusing on heating and cooling processes and employing a weak or variational formulation of the arising mathematical model. After finding the dimensionless numbers by a standard procedure, we obtain another set of dimensionless numbers associated with the weak formulation. Besides this, we apply dimension analysis to investigate distortion due to quenching. In particular, we prove that for quenching processes to cause plastification, (and, thus, distortion), a suitably generalized Biot number needs to be sufficiently large.
Convergence analysis of the SQP method for nonlinear mixed‐constrained elliptic optimal control problems
Authors: Griesse R. , Metla N. , Rösch A. 
Published: September 2008

AbstractSemilinear elliptic optimal boundary control problems with nonlinear pointwise mixed control‐state constraints are considered. Necessary and sufficient optimality conditions are given. The local quadratic convergence of the SQP method is proved and confirmed by numerical results.