bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrogen and Magnetism in Ga1‐xMnxAs
Authors: Goennenwein Sebastian T. B. , Wassner Thomas A. , Huebl Hans , Koeder Achim , Schoch Wladimir , Waag Andreas , Philipp Jan B. , Opel Matthias , Gross Rudolf , Stutzmann Martin , et al. et al. 
Published: January 2006

AbstractFor Abstract see ChemInform Abstract in Full Text.
Studies on the Synthesis of Imidazole‐metal Complexes and Their Characterization and Binding Mechanism with DNA
Authors: Zhang Shu‐Sheng , Niu Shu‐Yan , Jie Gui‐Fen , Li Xue‐Mei , Xu Hua , Shi Xin , Jiao Kui 
Published: January 2006

AbstractThree hexakis(imidazole)metallo complexes of Co, Cd and Ni were synthesized and spectroscopically characterized. The crystal and molecular structures have been determined by X‐ray crystallography analysis. The metal ions have an octahedral geometry with the MN6chromophore. The electrochemical experimental results indicate that both [Co(Im)6]Cl2·2HCl·2H2O (1) and [Ni(Im)6]Cl2·4H2O (3) [Imimidazole] could interact with DNA mainly by intercalation.
Reagentless Immunosensing Assay via Electrochemical Impedance for Hepatitis B Surface Antigen Monitoring Based on Polypyrrole and Gold Nanoparticles as Matrices
Authors: Fu Ying‐Zi , Yuan Ruo , Chai Ya‐Qin 
Published: January 2006

AbstractA novel simple immunosensing strategy for fabrication of hepatitis B surface antigen detection has been developed via electrochemical impedance spectroscopy (EIS) as a platform. At first, the conductive polymer polypyrrole (PPy) film was electrodeposited on a platinum electrode surface to adsorb the gold nanoparticles (nano‐Au) via the opposite‐charged adsorption technique, and then hepatitis B surface antibodies were adsorbed onto the surface of nano‐Au. The modification procedure was characterized by EIS. Such spectroscopy is attributed to the concomitant conductivity changes of the polymerized pyrrole film and gold nanoparticles. The factors influencing the performance of resulting immunoelectrode were studied in detail. The linear range of the resulting immunoelectrode is from 2.6 to 153.6 ng·mL−1 with a detection limit of 1.3 ng·mL−1 at 3σ. In addition, the experiment results indicate that antibody immobilized on this way exhibits a good sensitivity, selectivity, high stability and a long‐term maintenance of bioactivity, implying a great promising alternative approach for reagentless immunosensing analysis in the clinical diagnosis.
Ab Initio Study of Free‐Radical Polymerization: Polyethylene Propagation Kinetics
Authors: Van Cauter Karen , Van Speybroeck Veronique , Vansteenkiste Peter , Reyniers Marie‐Francoise , Waroquier Michel 
Published: January 2006

AbstractThe chain‐length dependence of the propagation rate coefficient for the free‐radical polymerization of ethylene was investigated on an ab initio basis. Polyethylene was chosen as a test system because of its structural simplicity. Ab initio density functional theory at the B3LYP/6‐31g(d) level was applied to study the kinetics of a set of addition reactions of a systematically growing radical alkyl chain to ethylene. These reactions are propagation steps in the free‐radical polymerization of ethylene. Special attention was paid to low normal modes corresponding to internal rotations (IR), since the latter are important for an accurate description of the partition functions. The effect of coupling of the IR modes is also discussed. A comparison is made with the propagation rate constant derived from experiment. The results indicate that the propagation rate coefficient has largely converged by the hexyl radical stage, though a weaker chain‐length dependence of kp for longer chains was detected.
Berry Pseudorotation Mechanism for the Interpretation of the 19F NMR Spectrum in PF5 by Ab Initio Molecular Dynamics Simulations
Authors: Raynaud Christophe , Maron Laurent , Daudey Jean‐Pierre , Jolibois Franck 
Published: January 2006

AbstractFor the first time, theoretical evidence that confirms the importance of the Berry pseudorotation process in the interpretation of the19F NMR spectrum of phosphorus pentafluoride (PF5) is presented. Ab initio molecular dynamics simulations have been performed to generate a large number of configurations used for NMR parameter computations at the density functional theory level. Two different temperatures were set to highlight the effect of pseudorotation process on the NMR spectrum. Average19F chemical shifts and spin–spin coupling constants calculated for the five fluorine atoms converge towards the NMR equivalence of the five atoms when the Berry pseudorotation mechanism is accounted for.
Structure of the HOOO Radical in Liquid Water: A Theoretical Study
Authors: Chalmet Stéphanie , Ruiz‐López Manuel F. 
Published: January 2006

AbstractThe HOOO radical is supposed to play a role in ozone chemistry, both in the gas phase and aqueous media. We discuss the influence of the solvent on the electronic and geometrical structure of this radical using density functional and high‐level ab initio calculations together with continuum, discrete, and discrete‐continuum solvent models. Solute–solvent electrostatic interactions are shown to be fundamental, and lead to a noticeable stabilization of the radical, which should adopt a trans conformation in aqueous media. In fact, no energy minimum for the cis conformation is predicted in these conditions.
The Equilibrium Structure of Ferrocene
Authors: Coriani Sonia , Haaland Arne , Helgaker Trygve , Jørgensen Poul 
Published: January 2006

AbstractThe molecular structures of ferrocene in the eclipsed (equilibrium) and staggered (saddle‐point) conformations have been determined by full geometry optimizations at the levels of second‐order Møller–Plesset (MP2) theory, coupled‐cluster singles‐and‐doubles (CCSD) theory, and CCSD theory with a perturbative triples correction [CCSD(T)] in a TZV2P+f basis set. Existing experimental results are reviewed. The agreement between the CCSD(T) results and experiment is in all cases excellent; the calculated structure parameters and the barrier to internal rotation of the ligand rings differ from the most accurate experimental values by less than two estimated standard deviations. The CCSD(T) calculations for single‐configuration‐dominated transition metal complexes such as ferrocene thus appear to have an accuracy comparable to that observed for molecules containing only first‐ and second‐row atoms, and to be of a quality similar to that obtained experimentally. A comparison with previous DFT results indicates that the B3LYP model gives overall the best DFT results, with a deviation of around 2 pm for the metal–carbon distance and smaller errors for the cyclopentadienyl rings.
Current Topics in Smectic Liquid Crystal Research
Authors: Lagerwall Jan P. F. , Giesselmann Frank 
Published: January 2006

AbstractInterest in the smectic liquid‐crystalline state of matter received a substantial boost with the discovery by Meyer in the mid‐1970s that a chiral smectic C (SmC*) phase exhibits a spontaneous electric polarization, and with the subsequent demonstration by Clark and Lagerwall of the surface‐stabilized SmC* ferroelectric liquid crystal at the beginning of the 1980s. Since then, chiral smectic phases and their plethora of polar effects have dominated the research in this field, which today has reached a mature state where the first commercial microdisplay applications are now shipping in millions‐per‐year quantities. In this Review we discuss some of the topics of highest interest in current smectic liquid crystal research, and address application‐relevant research (de Vries‐type tilting transitions without defect generation and high‐tilt antiferroelectric liquid crystals with perfect dark state) as well as more curiosity‐driven research (the nature and origin of the chiral smectic C subphases and their intermediate frustrated states between ferro‐ and antiferroelectricity).
A new approach of creating Au‐Sn solder bumps from electroplating
Authors: Wei Jiang 
Published: January 2006

AbstractA homogeneous melting eutectic Au/Sn solder bump for laser chip application has been developed. The under‐bump metallization consists of a Ni wetting layer, a plating seed layer of Pt/Au/Ti multi‐layer scheme. The solder is electroplated as a sequence of Ni, Au and Sn layers. The bump can be exposed to multi‐step reflow cycles. The reflow of the solder as plated starts with a phase forming process in the solid state which results in an eutectic‐like phase and the near eutectic dand z phases. The dand z phases dissolve during the liquid state stage of the reflow at temperatures between 300 and 350 °C. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermal expansion and structural properties of (CuAlTe2)1–x(CuAlSe2)x solid solutions
Authors: Korzun B. V. , Fadzeyeva A. A. , Bente K. , Schmitz W. , Schorr S. 
Published: January 2006

AbstractInvestigations of the thermal expansion of (CuAlTe2)1–x(CuAlSe2)x solid solutions in the temperature range from 100 to 800 K have been carried out for the first time. It has been demonstrated that the thermal expansion coefficient αL grows considerably in the temperature range from 100 to 300 K, whereas the temperature dependence above 300 K is rather weak. The isotherms of composition dependence of the thermal expansion coefficient αL for 100, 293, 500 and 800 K were constructed, and it was found that linear relations could express them. The Debye temperatures θD , the average mean‐square dynamic displacements $ \bar u ^2 $, the average root‐mean‐square amplitudes of thermal vibration RMS , the anion position parameter u using S. C. Abrahams & J. L. Bernstein (uAB ) and J. E. Jaffe & A. Zunger (uJZ ) models were calculated. The composition dependence of microhardness H using the phenomenological theory was also calculated, and it was discovered that this dependence has a non‐linear character with a maximum of 383 kg/mm2 at x=0.67. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The significance of telomeric aggregates in the interphase nuclei of tumor cells
Authors: Mai Sabine , Garini Yuval 
Published: January 2006

AbstractTelomeres are TTAGGG repetitive motifs found at the ends of vertebrate chromosomes. In humans, telomeres are protected by shelterin, a complex of six proteins (de Lange [2005] Genes Dev. 19: 2100–2110). Since (Müller [1938] Collecting Net. 13: 181–198; McClintock [1941] Genetics 26: 234–282), their function in maintaining chromosome stability has been intensively studied. This interest, especially in cancer biology, stems from the fact that telomere dysfunction is linked to genomic instability and tumorigenesis (Gisselsson et al. [2001] Proc. Natl. Acad. Sci. USA 98: 12683–12688; Deng et al. [2003] Genes Chromosomes Cancer 37: 92–97; DePinho and Polyak [2004] Nat. Genetics 36: 932–934; Meeker et al. [2004] Clin. Cancer Res. 10: 3317–3326). In the present overview, we will discuss the role of telomeres in genome stability, recent findings on three‐dimensional (3D) changes of telomeres in tumor interphase nuclei, and outline future avenues of research. J. Cell. Biochem. 97: 904–915, 2006. © 2006 Wiley‐Liss, Inc.
Intracellular acidification delays hormonal G2/M transition and inhibits G2/M transition triggered by thiophosphorylated MAPK in Xenopus oocytes
Authors: Sellier C. , Bodart J.‐F. , Flament S. , Baert F. , Gannon J. , Vilain J.‐P. 
Published: January 2006

AbstractXenopus oocyte maturation is analogous to G2/M transition and characterized by germinal vesicle breakdown (GVBD), spindle formation, activation of MPF and Mos‐Xp42Mpk1 pathways. It is accompanied prior to GVBD by a transient increase in intracellular pH. We determined that a well known acidifying compound, NH4Cl, delayed progesterone‐induced GVBD in a dose‐dependent manner. GVBD50 was delayed up to 2.3‐fold by 10 mM NH4Cl. Cyclin B2 phosphorylation, Cdk1 Tyr15 dephosphorylation as well as p39Mos accumulation, Xp42Mpk1 and p90Rsk phosphorylation induced by progesterone were also delayed by incubation of oocyte in NH4Cl. The delay induced by NH4Cl was prevented by injection of MOPS buffer pH 7.7. In contrast to acidifying medium, alkalyzing treatment such as Tris buffer pH 9 injections, accelerated GVBD, MPF and Xp42Mpk1 activation, indicating that pHi changes control early steps of G2/M dynamics. When injected in an immature recipient oocyte, egg cytoplasm triggers GVBD through MPF auto‐amplification, independently of protein synthesis. In these conditions, GVBD and Xp42Mpk1 activation were delayed by high concentration of NH4Cl, which never prevented or delayed MPF activation. Strickingly, NH4Cl strongly inhibited thiophosphorylated active MAPK‐induced GVBD and MPF activation. Nevertheless, Tris pH 9 did not have any effects on egg cytoplasm‐ or active MAPK‐induced GVBD. Taken together, our results suggest that dynamic of early events driving Xp42Mpk1 and MPF activation induced by progesterone may be negatively or positively regulated by pHi changes. However Xp42Mpk1 pathway was inhibited by acidification alone. Finally, MPF auto‐amplification loop was not sensitive to pHi changes. J. Cell. Biochem. 98: 287–300, 2006. © 2006 Wiley‐Liss, Inc.
High glucose increases extracellular matrix production in pancreatic stellate cells by activating the renin–angiotensin system
Authors: Ko Seung‐Hyun , Hong Oak‐Kee , Kim Ji‐Won , Ahn Yu‐Bai , Song Ki‐Ho , Cha Bong‐Yun , Son Ho‐Young , Kim Myung‐Jun , Jeong In‐Kyung , Yoon Kun‐Ho 
Published: January 2006

AbstractPancreatic stellate cells (PSCs) are involved in pancreatic inflammation and fibrosis. Recent studies have shown that blocking the renin–angiotensin system (RAS) attenuates pancreatic inflammation and fibrosis. However, there are few data about the direct effects of high glucose on extracellular matrix (ECM) protein synthesis and angiotensin II (Ang II) induction in PSCs. PSCs were isolated from male Sprague–Dawley rats and cultured in medium containing 5.5 mM (LG group) or 27 mM D‐glucose (HG group). Levels of Ang II and transforming growth factor‐β (TGF‐β) in culture media were measured and Ang II‐positive cells were counted. We used real‐time polymerase chain reaction (PCR) to detect Ang II receptor expression and Western blot analysis for the expression of ECM proteins such as connective‐tissue growth factor (CTGF) and collagen type IV. Cells were also treated with an Ang II‐receptor antagonist (candesartan, 10 µM) or angiotensin‐converting enzyme (ACE) inhibitor (ramiprilat, 100 nM). Thymidine uptake by PSCs increased fourfold with high glucose treatment. Ang II levels and the proportion of Ang II‐positive PSCs were significantly increased after 6 h under high‐glucose conditions. TGF‐β concentrations also increased significantly with high glucose. After 72 h, the expression of CTGF and collagen type IV proteins in high‐glucose cultures increased significantly and this increase was effectively attenuated by the candesartan or the ramiprilat. All together, high glucose induced PSCs proliferation and ECM protein synthesis, and these effects were attenuated by an Ang II‐receptor antagonist. The data suggest that pancreatic inflammation and fibrosis aggravated by hyperglycemia, and Ang II play an important role in this pathogenesis. J. Cell. Biochem. 98: 343–355, 2006. © 2006 Wiley‐Liss, Inc.
Microinjection of an antibody against the cysteine‐protease involved in male chromatin remodeling blocks the development of sea urchin embryos at the initial cell cycle
Authors: Puchi Marcia , Quiñones Karin , Concha Carolina , Iribarren Claudio , Bustos Paula , Morin Violeta , Genevière Anne Marie , Imschenetzky Maria 
Published: January 2006

AbstractWe reported recently that the inhibition of cysteine‐proteases with E‐64‐d disturbs DNA replication and prevents mitosis of the early sea urchin embryo. Since E‐64‐d is a rather general inhibitor of thiol‐proteases, to specifically target the cysteine‐protease previously identified in our laboratory as the enzyme involved in male chromatin remodeling after fertilization, we injected antibodies against the N‐terminal sequence of this protease that were able to inhibit the activity of this enzyme in vitro. We found that injection of these antibodies disrupts the initial zygotic cell cycle. As shown in this report in injected zygotes a severe inhibition of DNA replication was observed, the mitotic spindle was not correctly bipolarized the embryonic development was aborted at the initial cleavage division. Consequently, the injection of these antibodies mimics perfectly the effects previously described for E‐64‐d, indicating that the effects of this inhibitor rely mainly on the inhibition of the cysteine‐protease involved in male chromatin remodeling after fertilization. These results further support the crucial role of this protease in early embryonic development. J. Cell. Biochem. 98: 335–342, 2006. © 2006 Wiley‐Liss, Inc.
Proton MRS of the unilateral substantia nigra in the human brain at 4 tesla: Detection of high GABA concentrations
Authors: Öz Gülin , Terpstra Melissa , Tkáč Ivan , Aia Pratibha , Lowary Jodi , Tuite Paul J. , Gruetter Rolf 
Published: January 2006

AbstractParkinson's disease (PD) is characterized by loss of dopaminergic neurons in the substantia nigra (SN), the cause of which is unknown. Characterization of early SN pathology could prove beneficial in the treatment and diagnosis of PD. The present study shows that with the use of short‐echo (5 ms) Stimulated‐Echo Acquisition Mode (STEAM) spectroscopy and LCModel, a neurochemical profile consisting of 10 metabolites, including γ‐aminobutyric acid (GABA), glutamate (Glu), and glutathione (GSH), can be measured from the unilateral SN at 4 tesla. The neurochemical profile of the SN is unique and characterized by a fourfold higher GABA/Glu ratio compared to the cortex, in excellent agreement with established neurochemistry. The presence of elevated GABA levels in SN was validated with the use of editing, suggesting that partial volume effects were greatly reduced. These findings establish the feasibility of obtaining a neurochemical profile of the unilateral human SN by single‐voxel spectroscopy in small volumes. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Single breath‐hold whole‐heart MRA using variable‐density spirals at 3t
Authors: Santos Juan M. , Cunningham Charles H. , Lustig Michael , Hargreaves Brian A. , Hu Bob S. , Nishimura Dwight G. , Pauly John M. 
Published: January 2006

AbstractMultislice breath‐held coronary imaging techniques conventionally lack the coverage of free‐breathing 3D acquisitions but use a considerably shorter acquisition window during the cardiac cycle. This produces images with significantly less motion artifact but a lower signal‐to‐noise ratio (SNR). By using the extra SNR available at 3 T and undersampling k‐space without introducing significant aliasing artifacts, we were able to acquire high‐resolution fat‐suppressed images of the whole heart in 17 heartbeats (a single breath‐hold). The basic pulse sequence consists of a spectral‐spatial excitation followed by a variable‐density spiral readout. This is combined with real‐time localization and a real‐time prospective shim correction. Images are reconstructed with the use of gridding, and advanced techniques are used to reduce aliasing artifacts. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Correction of through‐plane deformation artifacts in stimulated echo acquisition mode cardiac imaging
Authors: Fahmy Ahmed S. , Pan Li , Stuber Matthias , Osman Nael F. 
Published: January 2006

AbstractAttempts to use a stimulated echo acquisition mode (STEAM) in cardiac imaging are impeded by imaging artifacts that result in signal attenuation and nulling of the cardiac tissue. In this work, we present a method to reduce this artifact by acquiring two sets of stimulated echo images with two different demodulations. The resulting two images are combined to recover the signal loss and weighted to compensate for possible deformation‐dependent intensity variation. Numerical simulations were used to validate the theory. Also, the proposed correction method was applied to in vivo imaging of normal volunteers (n = 6) and animal models with induced infarction (n = 3). The results show the ability of the method to recover the lost myocardial signal and generate artifact‐free black‐blood cardiac images. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Dual‐echo spiral in/in acquisition method for reducing magnetic susceptibility artifacts in blood‐oxygen‐level‐dependent functional magnetic resonance imaging
Authors: Li Tie‐Qiang , Takahashi Atsushi , Wang Yang , Mathews Vincent , Glover Gary H. 
Published: January 2006

AbstractMRI signal dropout in gradient recalled echo acquisitions limits the capability of blood‐oxygen‐level‐dependent functional magnetic resonance imaging (fMRI) to study activation tasks that involve the orbitofrontal, temporal, and basal areas of the brain where significant macroscopic magnetic susceptibility differences exist. Among the various approaches aimed to address this issue, the acquisition method based on spiral in/out trajectories is one of the most time‐efficient and effective techniques. In this study, we extended further the spiral in/out approach into 3D acquisition and compared the effectiveness of the different spiral in/out trajectory combinations in reducing signal dropout. The activation results from whole brain fMRI studies using complex finger tapping and breath‐holding tasks demonstrate that the acquisition method based on dual‐echo spiral in/in (DSPIN) trajectories is the most favorable. The DSPIN acquisition method has the following advantages: (1) It reduces most effectively signal dropout in the brain where magnetic susceptibility inhomogeneity is problematic and significantly improves the sensitivity to detect functional activations in those regions. (2) It significantly improves SNR in the whole brain by dual echo averaging without compromising functional contrast. (3) There is no reduction in time‐efficiency and spatial resolution. Magn Reson Med, 2006. Published 2006 Wiley‐Liss, Inc.
Noninvasive measurement of myocardial tissue volume change during systolic contraction and diastolic relaxation in the canine left ventricle
Authors: Rodriguez Ignacio , Ennis Daniel B. , Wen Han 
Published: January 2006

AbstractIn coronary circulation the flow in epicardial arteries and veins is observed to be pulsatile and out of phase with each other. Theoretical considerations predict that this phenomenon extends to all levels of the vascular tree and leads to a cyclic fluctuation of regional tissue volume. Intramyocardial tissue volume change between end‐systole and end‐diastole was measured noninvasively with MRI in 10 closed‐chest beagles. The displacement encoding with stimulated‐echo technique was used to obtain pixel‐by‐pixel tissue displacement field between end‐diastole and end‐systole and vice versa in the midlevel left ventricle, from which the 3D strain matrix and volume changes were calculated. The volume change was between 0.8 ± 0.5% (mean ± STD) in the epicardial layer and 1.5 ± 0.6% in the subendocardial layer of the left ventricle. Tissue volume fluctuation reflects the amount of arterial inflow in a heartbeat under the assumption that regional arterial inflow and venous outflow have little time overlap. The corresponding perfusion level was estimated to be from (1.0 ± 0.6) ml/min/g in the epicardial layer to (1.7 ± 0.6) ml/min/g in the subendocardial layer, in good agreement with microsphere measurements in the same dog model. The result supports the notion of high arterial resistance at the microvascular level from intramyocardial pressure during systole. Magn Reson Med, 2006. Published 2006 Wiley‐Liss, Inc.