bluuebunny/crossref_metadata_2025_split huggingface dataset:
Color centers in gamma‐irradiated YAP crystals grown by the Czochralski method
Authors: Dong Yongjun , Xu Jun , Zhou Guoqing , Zhao Guangjun , Su Liangbi , Xu Xiaodong , Li Hongjun , Si JiLiang 
Published: December 2006

AbstractColor centers in undoped YAP crystals induced by gamma‐irradiation were investigated by means of additional absorption spectra and thermal treatments. Color centers related to the 265 and 311 nm absorption bands were caused by Fe impurity ions and the charge state recharge of the Fe3+ and Fe2+ ions occurred during the gamma‐irradiation process. Gamma‐irradiation and air annealing affect the 400 nm AA (additional absorption) band intensity in an opposite way and (Vc––F+) defects should be responsible for this band. Further air and hydrogen annealing of un‐irradiated YAP shows that color centers at 193 nm may be associated with Vc defects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulations of nucleation of single‐walled carbon nanotubes
Authors: Luo Chenglin , Yu Hewu , Zhang Yiquan , Cai Linhui , He Xiangdong 
Published: December 2006

AbstractA common nucleation and growth mechanism of single‐walled carbon nanotubes based on a vapour–liquid–solid model has been proposed according to molecular dynamics simulations and related experiments. This mechanism can explain many important experimental observations such as similarities between samples synthesized using different techniques, minimum and maximum radii of single‐walled carbon nanotubes and the fact that single‐walled carbon nanotubes can only grow within a certain temperature interval. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Valence and coordination of chromium ions in ZnO–Sb2O3–B2O3 glass system by means of spectroscopic and dielectric relaxation studies
Authors: Srinivasa Reddy M. , Prasad S. V. G. V. A. , Veeraiah N. 
Published: December 2006

AbstractZnO–Sb2O3–B2O3 glasses containing different concentrations of chromium ions (introduced as CrO2–4) ranging from 0 to 1.0 mol% were prepared. A number of studies viz., differential thermal analysis, infrared, optical absorption, Raman and ESR spectra and dielectric properties (constant ε ′, loss tan δ, a.c. conductivity σac over a wide range of frequency and temperature) of these glasses have been carried out. The results have been analyzed in the light of different oxidation states of chromium ions. The analysis indicates that when the concentration of chromium ions is ∼0.2 mol%, these ions mostly exist in Cr6+ state, occupy network forming positions with CrO2–4 structural units and increase the rigidity of the glass network. When the concentration of the chromium ions is increased beyond 0.2 mol%, these ions seem to be reduced from Cr6+ state to Cr5+ and Cr3+ states. A gradual transformation of chromium ions from tetrahedral positions to octahedral positions could also be established from these results. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and infrared optical properties of evaporated erbium fluoride films
Authors: Su W. T. , Li B. , Liu D. Q. , Zhang F. S. 
Published: December 2006

AbstractErbium fluoride (ErF3) films were deposited on germanium substrate with different substrate temperatures. The films deposited at low substrate temperatures show amorphous structure, while those deposited at high substrate temperatures show polycrystalline structure with (002) preferred orientation. The roughness of the film increases from 0.47 nm for the amorphous film to tens of nanometres for the crystalline films deposited at high substrate temperatures. Furthermore, it has been found that the surface morphology of the crystalline ErF3 films is modulated by the tensile stress in thin films. The infrared optical constants of the films were determined by fitting the transmission spectrum in the wavelength range from 2 to 10 μm using the Lorentz oscillator model. Both the refractive indices and extinction coefficients decrease with increasing substrate temperature. The minimum refractive index and extinction coefficient of the ErF3 film at a wavelength of 10 μm is as low as n = 1.32 and k = 0.006, respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High Q ‐factor NiCuZn ferrite with nanocrystalline ferrite particles and Co2O3 additives
Authors: Su Hua , Zhang Huaiwu , Tang Xiaoli , Liu Baoyuan , Jin Yulan 
Published: December 2006

AbstractThis work focuses on the effects of nanocrystalline ferrite particles (NFPs) on the sintering behaviour and magnetic properties of NiCuZn ferrite for multilayer chip inductor use. It was found that the NFPs could evidently improve the sintering behaviour of the ferrite because of their large surface free energy. Because the NFPs had the same chemical composition as the NiCuZn ferrite, samples with appropriate NFPs added could show better magnetic properties than samples with added Bi2O3. Also, to further increase the Q ‐factor of the NiCuZn ferrite, the effects of Co2O3 additive on the magnetic properties of the NFP‐added ferrite were studied. The results revealed that the permeability of the ferrite decreased monotonically due to added Co2O3; the Q ‐factor first increased and reached its peak with 0.2 wt% Co2O3 added, whereupon it began to decrease. With 30 wt% NFPs and 0.2 wt% Co2O3 additives, the NiCuZn ferrite showed a high Q ‐factor of more than 200. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recovery of dry etch‐induced damage of nano‐patterned GaN‐based light‐emitting diodes by rapid‐thermal‐annealing
Authors: Hong Hyun‐Gi , Kim S.‐S. , Kim D.‐Y. , Lee Takhee , Kim Kyoung‐Kook , Song June‐O. , Cho J. H. , Seong Tae‐Yeon 
Published: December 2006

AbstractThe effect of rapid‐thermal‐annealing on the performance of near‐UV GaN‐based light‐emitting diodes (LEDs) fabricated with nano‐patterned p‐type electrodes has been investigated. One‐dimensional (1‐D) nano‐patterns were formed on Cu‐doped indium oxide (CIO)/indium tin oxide (ITO) p‐electrode by sur‐ face relief grating and dry etching techniques. After the nano‐patterning, some of the samples are rapid‐thermal‐annealed at 530 and 630 °C in either air or nitrogen ambient. LEDs made with samples annealed 530 °C show much better electrical characteristics as compared to unannealed samples. In particular, LEDs with samples annealed 530 °C in air show higher output power (at 20 mA) and much reduced leakage current as compared to LEDs with unannealed samples. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magneto‐transport properties of NiMnSb thin films on InSb single crystals: Negative giant magnetoresistance
Authors: Gardelis S. , Androulakis J. , Viskadourakis Z. , Papadopoulou E. L. , Giapintzakis J. , Rai S. , Lodha G. S. , Roy S. B. 
Published: December 2006

AbstractIn this study we investigated the magneto‐transport properties of the ohmic contact between polycrystalline NiMnSb thin films grown by pulsed laser deposition and n‐type degenerate InSb (100) substrates. An unusual negative giant magnetoresistance (n‐GMR) effect is found when the external magnetic field is parallel to the in‐plane current direction. A similar effect is also observed when Ni films are deposited on InSb substrates. On the other hand, no n‐GMR effect is displayed when the deposited film is nonmagnetic. Grazing‐incidence X‐ray reflectometry shows the formation of a low‐density NiMnSb layer at the interface. The presence of such a layer coincides with the appearance of the n‐GMR.We argue that the n‐GMR effect is due to magnetic precipitates formed at the interface during the growth of the magnetic films. We propose that these precipitates align their magnetic moments in the direction of the external magnetic field and thus, the spin dependent scattering of the electrons is reduced. The effect of these precipitates on the magnetoresistance depends on the thermal processing of the system. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formation of precipitates in Mn doped ZnO layers deposited by magnetron sputtering
Authors: Abouzaid M. , Ruterana P. , Liu C. , Morkoç H. 
Published: December 2006

AbstractThe precipitation of Mn rich phases in ZnO layers deposited by magnetron sputtering has been investigated as well as the precipitates influence on the magnetic properties. On top of sapphire (0001) substrates, the formation of Mn rich precipitates is observed following the deposition of Zn(Mn)O layers above 500 °C, the size of the precipitates is shown to increase with the Mn concentration. For Zn(Mn)O layers deposited on GaN in similar conditions, no precipitates have been seen to form, however the quality of layers highly improved when the temperature was brought down to 500 °C. At this optimal temperature, the measured magnetic properties are best in layers deposited on both substrates, such layers do not contain any of the observed Mn rich precipitates. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microscopic investigation of the structural and electronic properties of ion implanted Mn–Ge alloys
Authors: Ottaviano L. , Passacantando M. , Verna A. , Parisse P. , Picozzi S. , Impellizzeri G. , Priolo F. 
Published: December 2006

AbstractWe review recent results of an extensive experimental study of ion implanted Mn–Ge(100) alloys fabricated by systematically varying the Mn dose (in the range 1–4 × 1016 at/cm2) and the Ge substrate temperature (from room temperature up to 300 °C) during the implantation. The samples have been investigated by means of X‐ray photoemission spectroscopy, scanning electron microscopy, transmission electron microscopy, electron energy loss spectroscopy, and scanning tunneling microscopy and spectroscopy. The combined investigation allows to determine, with an unprecedented deal of information at the nanometer scale, the morphological, structural, and electronic properties of such alloys. We evidence a porous to continuous transition in the surface morphology of the implanted layer when passing from 190 to 240 °C implantation substrate temperature. At higher implantation temperatures we directly demonstrate Mn dilution in the Ge matrix and also show the presence of extrinsic phases like Mn rich clusters. The presence of Mn rich precipitates is directly evidenced with transmission electron microscopy and corresponding energy loss Mn elemental maps taken at the Mn L3 edge. Larger clusters (with diameter greater that 10 nm) are in the Mn5Ge3 phase and are metallic, as demonstrated with scanning tunneling spectroscopy. Smaller clusters are still Mn rich but typically in an amorphous phase. These clusters are semiconducting with 0.45 eV energy gap. The results on the local electronic structure of the alloys investigated with scanning tunneling spectroscopy are also discussed in comparison with ab‐initio calculations. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Detection of sibutramine administration: a gas chromatography/mass spectrometry study of the main urinary metabolites
Authors: Strano‐Rossi Sabina , Colamonici Cristiana , Botrè Francesco 
Published: December 2006

AbstractA gas chromatographic/mass spectrometric (GC/MS) study aimed at identifying the metabolites of sibutramine (1‐(4‐chlorophenyl)‐N,N‐dimethyl‐α‐(2‐methylpropyl)cyclobutanemethanamine) in urine is described. Urinary excretion of sibutramine metabolites following the oral administration of a single dose of sibutramine was followed by GC/MS analysis. After identification of the chromatographic signals corresponding to the six main urinary metabolites, the fragmentation pattern was studied in electron ionization (EI) mode after derivatization to the corresponding methyl and trimethylsilyl derivatives. Urine samples were pretreated according to a reference procedure (liquid/liquid separation, enzymatic hydrolysis, pre‐concentration under a stream of nitrogen and derivatization, either under thermal incubation and by microwave irradiation). All sibutramine metabolites were excreted as glucuroconjugates, and retain the chiral carbon present in the sibutramine skeleton. The metabolites identified included mono‐desmethylsibutramine (nor‐sibutramine), bi‐desmethylsibutramine (nor‐nor‐sibutramine), and the corresponding hydroxylated compounds, the hydroxylation taking place either on the cyclobutane or on the isopropyl chain. The excretion profiles of the different metabolites were also evaluated. From an analytical point of view, the method can be applied to different fields of forensic analytical toxicology, including anti‐doping analysis. Although the lack of certified reference materials does not allow a precise determination of the limits of detection (LODs) of all the sibutramine metabolites, an estimation taking into account the response factor of similar compounds ensures that all metabolites are still clearly detectable in a range of concentrations between 10 and 50 ng/mL, thus satisfying the minimum required performance limits (MRPLs) of the World Anti‐Doping Agency (WADA). Copyright © 2006 John Wiley & Sons, Ltd.
A gas‐inlet system coupled with a Knudsen cell mass spectrometer for high‐temperature studies
Authors: Brutti Sergio , Balducci Giovanni , Gigli Guido 
Published: December 2006

AbstractA gas‐inlet system coupled with a Knudsen effusion mass spectrometer has been developed to study at high temperature the interaction of solids and vapors with reactive permanent gases, such as H2 and O2, directly introduced into the cell from external low‐pressure reservoirs (pressure range: 10−4 < p < 1 bar). By selecting the gas flow from the external reservoir the pressures of the gases inside the Knudsen cell can be quantitatively controlled over three orders of magnitude, approximately from 10−8 to 5·10−5 bar. Mixtures of two different gases can be introduced into the cell, controlling their partial pressures independently. The capabilities of the device have been tested with four gas‐solid systems: PbO(s) + O2(g), GeO2(s) + O2(g), Ga(s) + H2(g) and Au(s) + H2(g), by studying the relevant high‐temperature equilibria. The results obtained for the dissociation energies of the diatomic molecules PbO(g), GeO(g), GaH(g), and AuH(g) compare well with the literature data giving confidence in the reliability and versatility of the method. Preliminary experiments on the in situ formation of H2O(g) in the Knudsen cell by the introduction of controlled gaseous H2/O2 mixtures are also presented. Copyright © 2006 John Wiley & Sons, Ltd.
Determination of the active and inactive metabolites of prasugrel in human plasma by liquid chromatography/tandem mass spectrometry
Authors: Farid Nagy A. , McIntosh Mary , Garofolo Fabio , Wong Ernest , Shwajch Amanda , Kennedy Monika , Young Michelle , Sarkar Pratibha , Kawabata Kiyoshi , Takahashi Makoto , Pang Henrianna 
Published: December 2006

AbstractTwo fast and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS)‐based bioanalytical assays were developed and validated to quantify the active and three inactive metabolites of prasugrel. Prasugrel is a novel thienopyridine prodrug that is metabolized to the pharmacologically active metabolite in addition to three inactive metabolites, which directly relate to the formation and elimination of the active metabolite. After extraction and separation, the analytes were detected and quantified using a triple quadrupole mass spectrometer using positive electrospray ionization. The validated concentration range for the inactive metabolites assay was from 1 to 500 ng/mL for each of the three analytes. Additionally, a 5× dilution factor was validated. The interday accuracy ranged from −10.5% to 12.5% and the precision ranged from 2.4% to 6.6% for all three analytes. All results showed accuracy and precision within ±20% at the lower limit of quantification and ±15% at other levels. The validated concentration range for the active metabolite assay was from 0.5 to 250 ng/mL. Additionally, a 10× dilution factor was validated. The interbatch accuracy ranged from −7.00% to 5.98%, while the precision ranged from 0.98% to 3.39%. Derivatization of the active metabolite in blood with 2‐bromo‐3'‐methoxyacetophenone immediately after collection was essential to ensure the stability of the metabolite during sample processing and storage. These methods have been applied to determine the concentrations of the active and inactive metabolites of prasugrel in human plasma. Copyright © 2006 John Wiley & Sons, Ltd.
Quantitative determination of isorhamnetin, quercetin and kaempferol in rat plasma by liquid chromatography with electrospray ionization tandem mass spectrometry and its application to the pharmacokinetic study of isorhamnetin
Authors: Lan Ke , Jiang Xuehua , He Jianling 
Published: December 2006

AbstractA simple and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for the quantification of quercetin, kaempferol and isorhamnetin in rat plasma. After being treated with β‐glucuronidase and sulfatase, the analytes were extracted by liquid/liquid extraction with the internal standard (IS; baicalein). The chromatographic separation was performed on a Diamonsil C18 column with a mobile phase consisting of 2% formic acid/methanol (10:90, v/v) at a flow rate of 1.00 mL/min, with a split of 200 µL to the mass spectrometer. Validation results indicated that the lower limit of quantification (LLOQ) was 1 ng · mL−1. The assay exhibited a linear range of 1–200 ng · mL−1 and gave a correlation coefficient of 0.9980 or better for each analyte. Quality control samples (1, 5, 20 and 100 ng · mL−1) in six replicates from each of three different runs demonstrated an intra‐assay precision (RSD) of 1.1–8.9%, an inter‐assay precision of 1.6–10.8%, and an overall accuracy (bias) of <13.4%. The extraction recovery of each analyte and internal standard was 70–80%. In the present study, we have investigated the pharmacokinetic profiles of isorhamnetin after oral application in rats equipped with a jugular catheter. After oral dosing of isorhamnetin, the mean values (n = 10) of Cmax were 57.8, 64.8 and 75.2 ng · mL−1 which were achieved at a Tmax of 8.0, 6.4 and 7.2 h for oral doses of 0.25, 0.5 and 1.0 mg · kg−1 body weight, respectively. The corresponding mean values for isorhamnetin area under the curver (AUC) from 0 to 60 h were 838.2, 1262.8, 1623.4 ng · h · mL−1. Our results further demonstrated that the samples analyzed showed isorhamnetin could not be transformed into quercetin or kaempferol in rats, indicating that the demethylation of the 3′‐oxymethyl group of isorhamnetin does not occur in Wistar rats. Copyright © 2006 John Wiley & Sons, Ltd.
Development of a liquid chromatography/electrospray ionization tandem mass spectrometric method for the determination of hydroxyl radical
Authors: Yang Fen , Zhang Ruiping , He Jiuming , Abliz Zeper 
Published: December 2006

AbstractA rapid method combining liquid chromatography with electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) was developed for the determination of the hydroxyl radical (·OH). ·OH generated via Fenton reaction was spin‐trapped by 5,5‐dimethyl‐1‐pyrroline N‐oxide (DMPO) and then analyzed by LC/ESI‐MS/MS in multiple reaction monitoring (MRM) mode, using N‐methyl‐2‐pyrrolidone (NMP) as the internal standard. The peak area ratio of DMPO‐OH to NMP positively correlated with the concentration of ·OH. The relative standard deviation (RSD) of the method was 1.13% (n = 8). The present method was successfully applied to evaluate the ·OH scavenging capacity of several phenolic acids. Copyright © 2006 John Wiley & Sons, Ltd.
Screening and analysis of the multiple absorbed bioactive components and metabolites of Dangguibuxue decoction by the metabolic fingerprinting technique and liquid chromatography/diode‐array detection mass spectrometry
Authors: Wang Ping , Liang Yizeng , Zhou Neng , Chen Benmei , Yi Lunzhao , Yu Yan , Yi Zhibiao 
Published: December 2006

AbstractBased on the metabolic fingerprinting technique and liquid chromatography/diode array detection mass spectrometry (LC/DAD‐MS), a method for rapid screening and analysis of the multiple absorbed bioactive components and metabolites of an oral solution of Dangguibuxue decoction (ODD) in rabbit plasma after oral administration of ODD was developed. The results obtained from a comprehensive comparative analysis of the fingerprints of the ODD and its metabolic fingerprints in rabbit plasma indicated that 46 components in the ODD were absorbed into the rabbit's body. Of them, ten components were tentatively identified from their MS and UV spectra and retention behaviors by comparing the results with the reported literature. They were calycosin‐7‐O‐β‐D‐glycoside, (6aR,‐11aR)‐hydroxy‐9,10‐dimethoxypterocarpan‐3‐O‐β‐D‐glycoside, ononin, L‐3‐hydroxy‐9,10‐dimethoxypterocarpan, formononetin, (3R)‐7,2'‐dihydroxy‐3',4'‐dimethoxyisoflavan, sedanenolide, E‐ligustilide, Z‐ligustilide, and Z‐butylidenephthalide. In addition, 21 components were only found in the metabolic fingerprints, which suggested that they might be metabolites of some components in the ODD. The findings demonstrated that the proposed method could be used to rapidly and simultaneously analyze and screen the multiple absorbed bioactive constituents and metabolites in a formula of traditional Chinese medicines (TCMs) by comparing and contrasting the chromatographic fingerprints with its metabolic fingerprints. This is very important not only for the pharmaceutical discovery process and the quality control of crude drugs, but also to explain the curative mechanism of TCMs. Copyright © 2006 John Wiley & Sons, Ltd.
Fourier transform mass spectrometry to monitor hyaluronan–protein interactions: use of hydrogen/deuterium amide exchange
Authors: Seyfried Nicholas T. , Atwood James A. , Yongye Austin , Almond Andrew , Day Anthony J. , Orlando Ron , Woods Robert J. 
Published: December 2006

AbstractThe use of Fourier transform mass spectrometry (FTMS) to monitor noncovalent complex formation in the gas phase under native conditions between the Link module from human tumor necrosis factor stimulated gene‐6 (Link_TSG6) and hyaluronan (HA) oligosaccharides is reported. In particular, a titration experiment with increasing concentrations of octasaccharide (HA8) to protein produced a noncovalent complex with 1:1 stoichiometry when the oligosaccharide was in molar excess. However, in the presence of a molar excess of tetrasaccharide (HA4) nearly all proteins and oligosaccharides were observed in their unbound charge states. These results are consistent with solution‐phase properties for this interaction in which HA8, but not HA4, supports high affinity Link_TSG6 binding. Hydrogen/deuterium amide exchange mass spectrometry (H/D‐EX MS) was also utilized to investigate the level of global deuterium incorporation, over time, for Link_TSG6 in both the absence and presence of HA8. After dilution into quenching conditions, deuterium incorporation reached limiting asymptotic values of 37 and 26 deuterons for the free and bound protein at 240 and 480 min, respectively, indicating that the oligosaccharide interferes with amide exchange on binding. To detect sequence‐specific deuterium incorporation, pepsin digestion of Link_TSG6 in both the absence and presence of HA8 was performed. A level of deuterium incorporation of 10–30% was observed for peptides analyzed in free Link_TSG6. Interestingly, HA8 blocked some sites of proteolysis in Link_TSG6 compared to the free protein. Molecular modeling indicated that amino acids proximal to the ligand correlated with regions of the protein that were resistant to enzymatic digestion. Of the peptides that could be analyzed by H/D‐EX MS in the presence of the ligand, a 30–60% reduction in deuterium incorporation, relative to the free protein, was observed, even for those sequences not directly involved in HA binding. These results support the utility of FTMS as a method for the characterization of protein–carbohydrate interactions. Copyright © 2006 John Wiley & Sons, Ltd.