bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous quantification of a non‐nucleoside reverse transcriptase inhibitor efavirenz, a nucleoside reverse transcriptase inhibitor emtricitabine and a nucleotide reverse transcriptase inhibitor tenofovir in plasma by liquid chromatography positive ion electrospray tandem mass spectrometry
Authors: Nirogi Ramakrishna , Bhyrapuneni Gopinadh , Kandikere Vishwottam , Mudigonda Koteshwara , Komarneni Prashanth , Aleti Raghupathi , Mukkanti K.
Published: October 2008

A high‐performance liquid chromatography/positive ion electrospray tandem mass spectrometry method for the simultaneous quantification of efavirenz, emtricitabine and tenofovir was developed and validated with 100 µL human plasma. Following solid‐phase extraction, the analytes were separated using a gradient mobile phase on a reverse‐phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M + H]+ ions, m/z 316 to 168 for efavirenz, m/z 248–130 for emtricitabine and m/z 288–176 for tenofovir, m/z 482–258 for rosuvastatin (IS), m/z 260–116 for propranolol (IS). The method exhibited a 100‐fold linear dynamic range for all the three analytes in human plasma (20–2000, 2–200 and 20–2000 ng/mL for efavirenz, emtricitabine and tenofovir respectively). The lower limit of quantification was 2 ng/mL for emtricitabine and 20 ng/mL for both efavirenz and tenofovir with a relative standard deviation of less than 11%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The total chromatographic run time of 4 min for each sample made it possible to analyze more than 250 human plasma samples per day. The method is precise and sensitive enough for its intended purpose. The method is also successfully applied to quantify efavirenz, emtricitabine and tenofovir concentrations in a rodent pharmacokinetic study. Copyright © 2008 John Wiley & Sons, Ltd.
Clopidogrel: review of bioanalytical methods, pharmacokinetics/pharmacodynamics, and update on recent trends in drug–drug interaction studies
Authors: Mullangi Ramesh , Srinivas Nuggehally R.
Published: October 2008

Clopidogrel, owing to its excellent inhibitory property of platelet aggregation, is used to reduce the cardiovascular risks in patients with multiple co‐morbid conditions such as stroke, myocardial infarction and atherosclerosis. The current review focuses distinctly on three aspects: (a) an in‐depth coverage on the bioanalytical methods for the quantification of clopidogrel and its inactive carboxylic acid metabolite as well as the active metabolite in pre‐clinical and clinical samples; (b) an overview of the pharmacokinetic/pharmacodynamic aspects of clopidogrel; and (c) enumerating the key findings from drug–drug interaction studies of clopidogrel with various co‐substrates such as lanzoprazole, fluvastatin, atorvastatin, pravastatin, digoxin, ketoconazole, donezepil and theophylline. Copyright © 2008 John Wiley & Sons, Ltd.
A Polylinker Approach to Reductive Loop Swaps in Modular Polyketide Synthases
Authors: Kellenberger Laurenz , Galloway Ian S. , Sauter Guido , Böhm Günter , Hanefeld Ulf , Cortés Jesús , Staunton James , Leadlay Peter F.
Published: October 2008

Multiple versions of the DEBS 1‐TE gene, which encodes a truncated bimodular polyketide synthase (PKS) derived from the erythromycin‐producing PKS, were created by replacing the DNA encoding the ketoreductase (KR) domain in the second extension module by either of two synthetic oligonucleotide linkers. This made available a total of nine unique restriction sites for engineering. The DNA for donor “reductive loops,” which are sets of contiguous domains comprising either KR or KR and dehydratase (DH), or KR, DH and enoylreductase (ER) domains, was cloned from selected modules of five natural PKS multienzymes and spliced into module 2 of DEBS 1‐TE using alternative polylinker sites. The resulting hybrid PKSs were tested for triketide production in vivo. Most of the hybrid multienzymes were active, vindicating the treatment of the reductive loop as a single structural unit, but yields were dependent on the restriction sites used. Further, different donor reductive loops worked optimally with different splice sites. For those reductive loops comprising DH, ER and KR domains, premature TE‐catalysed release of partially reduced intermediates was sometimes seen, which provided further insight into the overall stereochemistry of reduction in those modules. Analysis of loops containing KR only, which should generate stereocentres at both C‐2 and C‐3, revealed that the 3‐hydroxy configuration (but not the 2‐methyl configuration) could be altered by appropriate choice of a donor loop. The successful swapping of reductive loops provides an interesting parallel to a recently suggested pathway for the natural evolution of modular PKSs by recombination.
Enantioselective plasma protein binding of propafenone: Mechanism, drug interaction, and species difference
Authors: Hong Yanjun , Tang Yihong , Zeng Su
Published: October 2008

The interaction of propafenone (PPF) enantiomers with human plasma, human serum albumin (HSA), α1‐acid glycoprotein (AGP), as well as with plasma from rat, rabbit, and cow was investigated using indirect chiral high performance liquid chromatography (HPLC) and ultrafiltration techniques. The stronger binding of the S‐PPF found in human plasma was due to AGP. Two classes of binding sites in AGP were identified: one with high‐affinity and small binding capacity (K1(S) = 7.65 × 106 M−1, n1(S) = 0.50; K1(R) = 2.81 × 106 M−1, n1(R) = 0.46), which revealed stereoselectivity; the other with low‐affinity and high‐binding capacity (n2(S) K2(S) = 9.95 × 103 M−1; n2(R) K2(R) = 9.74 × 103 M−1). The binding to HSA was found to be weak and not enantioselective (nKS = 2.08 × 103 M−1, nKR = 2.05 × 103 M−1). The interaction between enantiomers observed in human plasma was confirmed as a competitive type interacting at the high‐affinity site in AGP. The binding mode of both enantiomers with AGP was mainly hydrophobic bond. PPF enantiomers had higher‐binding affinity for the F‐S variant of human AGP. Drug‐drug binding interaction studies showed that verapamil, diazepam, nifedipine, furosemide, nitrendipine, and nimodipine did not affect the binding of PPF enantiomers except quinidine and aprindine at the therapeutic concentration. Comparative studies indicated considerable species‐dependent binding stereoselectivity between plasma of the four species investigated. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
Disparate effects of different mutations in plakoglobin on cell mechanical behavior
Authors: Huang Hayden , Asimaki Angeliki , Lo Denise , McKenna William , Saffitz Jeffrey
Published: October 2008

Mutations in genes encoding desmosomal proteins have been implicated in the pathogenesis of heart and skin diseases. This has led to the hypothesis that defective cell‐cell adhesion is the underlying cause of injury in tissues that repeatedly bear high mechanical loads. In this study, we examined the effects of two different mutations in plakoglobin on cell migration, stiffness, and adhesion. One is a C‐terminal mutation causing Naxos disease, a recessive syndrome of arrhythmogenic right ventricular cardiomyopathy (ARVC) and abnormal skin and hair. The other is an N‐terminal mutation causing dominant inheritance of ARVC without cutaneous abnormalities. To assess the effects of plakoglobin mutations on a broad range of cell mechanical behavior, we characterized a model system consisting of stably transfected HEK cells which are particularly well suited for analyses of cell migration and adhesion. Both mutations increased the speed of wound healing which appeared to be related to increased cell motility rather than increased cell proliferation. However, the C‐terminal mutation led to dramatically decreased cell‐cell adhesion, whereas the N‐terminal mutation caused a decrease in cell stiffness. These results indicate that different mutations in plakoglobin have markedly disparate effects on cell mechanical behavior, suggesting complex biomechanical roles for this protein. Cell Motil. Cytoskeleton 2008. © 2008 Wiley‐Liss, Inc.
A tropomyosin 1 induced defect in cytokinesis can be rescued by elevated expression of cofilin
Authors: Thoms Julie A. I. , Loch Heather M. , Bamburg James R. , Gunning Peter W. , Weinberger Ron P.
Published: October 2008

Cytokinesis in eukaryotic cells is mediated by the contractile ring, an actomyosin‐based structure which provides the force required to separate daughter cells. Isoforms of the actin‐binding protein tropomyosin are also localised to the contractile ring in both fission yeast and human astrocytes. Although tropomyosin is required for cytokinesis in yeast, its precise role in the contractile ring is unknown. In this study we find that increased expression of a single tropomyosin isoform, tropomyosin 1, in U373MG astrocytoma cells leads to multinucleated cells and mitotic spindle defects. Furthermore, cells expressing increased levels of tropomyosin 1 usually fail to complete cytokinesis and this is accompanied by reduced accumulation of actin depolymerising factor/cofilin in the contractile ring. Adenovirus mediated expression of cofilin is able to relieve the tropomyosin 1 induced effects on cytokinesis. We conclude that tropomyosin 1 and cofilin play antagonistic roles within the contractile ring and that the balance between tropomyosin 1 and cofilin expression is important for cytokinesis. Cell Motil. Cytoskeleton 2008. © 2008 Wiley‐Liss, Inc.
The proper use of indices of metamerism
Authors: Berns Roy S.
Published: October 2008

General (spectral) and special (colorimetric) indices of metamerism have been developed to evaluate match quality for metameric and parameric specimens. For a parameric pair, in which there is not an exact colorimetric match for a reference observer and illuminant, various corrections can be used to adjust one of the stimuli such that an exact match is achieved. These adjustments can be spectral or colorimetric. In cases where the mismatch is large, the resultant metameric index may be misleading. A small index of metamerism and a large color difference under the reference conditions has a different interpretation than its converse. This is demonstrated for blue, yellow, magenta artist paints matching a spectrally nonselective gray. The implication is that special indices of metamerism should be calculated only for a limited range of color differences under the reference condition. It is suggested that metameric indices should not be calculated for pairs having a mismatch beyond a threshold value, for example, 5 ΔE. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 509–512, 2008
Insight into Markovnikov Reactions of Alkenes in Terms of Ab Initio and Molecular Face Theory
Authors: Yang Zhong‐Zhi , Ding Yan‐Li , Zhao Dong‐Xia
Published: October 2008

Electrophilic additions of hydrogen halides to alkenes in the gas phase are investigated with a high‐level ab initio method, MP2/6‐311+G(3df,2p). Based on this, the interesting features of these reactions along the IRC routes are characterized by the molecular face (MF) theory. For an alkene at the initial state, if the representative electron density (ED) encoded on the molecular face (MF) of the Markovnikov (M) carbon atom (the carbon with more hydrogen atoms) is larger than that of the anti‐Markovnikov (AM) carbon atom (the carbon with fewer hydrogen atoms), the electrophilic addition reaction is predicted to proceed along the Markovnikov addition route; in the reverse situtation, the anti‐Markovnikov addition route would be slightly preferred. It is then demonstrated that for a series of alkenes, the difference between activation energies of Markovnikov and anti‐Markovnikov addition routes [ΔE#(M−AM)] has a good linear correlation with sign(KED)K2ED, where KED is characteristic of the electron density (ED) at the π region in the initial state of the alkenes. Interestingly, there is a good linear correlation between our sign (KED)K2ED and the absolute values of difference in the core ionization energy between M and AM carbon atoms obtained by others (L. J. Sæthre, T. D. Thomas, S. Svensson J. Chem. Soc. P2 1997, 2, 749.) in terms of the experimental study. In addition, the spatial dynamic changing features of the MF faces and interesting pictures of the electron transfer are clearly shown during the course of the electrophilic addition reactions. These results indicate that not only regioselectivity, but also activation energy and reactivity correlate with the π charge distribution in the initial state of the alkenes for electrophilic addition reactions.
Dissymetrization of molecular crystals: a driving force for property formation
Authors: Hulliger J. , Batagiannis A.
Published: October 2008

Phenomena of dissymetrization of molecular crystals are reviewed which lead to sector wise polar properties. Orientational disorder of prolate‐type dipolar molecules taking place at attachment sites can produce partial polar alignment of dipoles in corresponding growth sectors of molecular crystals nucleating into topologically centric packings. As a result bi‐polar crystals are obtained. In case of native polar groups, Monte Carlo simulations predict a basic behaviour for pyroelectric molecular crystals: the dipoles belonging to sectors of either the plus or minus direction of the unique axis show a non‐vanishing probability to be gradually reversed. Domain reversal may start upon a single orientational defect developing into complete sector reversal. Basic features of growth induced stochastic polarity formation are confirmed by scanning pyroelectric microscopy, phase sensitive second harmonic generation microscopy and x‐ray scattering. Real systems comprise channel‐type inclusion compounds, single component molecular crystals, solid solutions and long chain proteins in natural tissues. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear optical properties of lithium sulfate monohydrate
Authors: Bayarjargal L.
Published: October 2008

In this paper, all eight tensor components of the nonlinear optical susceptibility tensor for second harmonic generation were determined for monoclinic non‐centrosymmetric lithium sulfate monohydrate, Li2SO4·H2O, using the Maker fringe technique at the wavelength λ=1064 nm. The largest component of the nonlinear optical susceptibility tensor was 0.34 pm/V. This crystal has the maximum effective value 0.13 pm/V along the phase matching directions at type I and 0.10 pm/V at type II. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Systematic, properties, and structure predictions of new borate materials
Authors: Belokoneva E. L.
Published: October 2008

New borates with the non‐linear optical properties, obtained and investigated in Moscow State University in the last years, are reviewed. The positions of compounds in systematic were determined including complicate cases using topology and symmetry analysis of anionic radicals with the separation of blocks, typical for borate groups. Such approach revealed structural correlations between borates and silicates and led to prediction of new structures, two of which are realized. The origin of properties is connected with the highly polarizable electron density on lone pair or asymmetric bonds, presented in the structures. Experimental observation electron density distrubution has been made for Pb‐hilgardite, a crystal with the high optical non‐linearity. Different approaches to the structure‐properties relation are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and spectroscopic study of Mg13.4(OH)6(HVO4)2(H0.2VO4)6
Authors: Đorđević T. , Karanović Lj. , Tillmanns E.
Published: October 2008

Single‐crystals of the polar compound magnesium hydrogen vanadate(V), Mg13.4(OH)6(HVO4)2(H0.2VO4)6, were synthesized hydrothermally. It represents the first hydrogen vanadate(V) among inorganic compounds. Its structure was determined by single‐crystal X‐ray diffraction [space group P 63mc, a = 12.9096(2), c = 5.0755(1) Å, V = 732.55(2) Å³, Z = 1]. The crystal structure of Mg13.4(OH)6(HVO4)2(H0.2VO4)6 consists of well separated, vacancy‐interrupted chains of face sharing Mg2O6 octahedra, with short Mg2—Mg2 distances of 2.537(1) Å, embedded in a porous magnesium vanadate 3D framework having the topology of the zeolite cancrinite. All three hydrogen positions in the structure were confirmed by FTIR spectroscopy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electric‐field‐induced internal deformation in piezoelectric BiB3O6 crystals
Authors: Schmidt O. , Gorfman S. , Pietsch U.
Published: October 2008

For the first time electric‐field‐induced atomic displacements (internal strains) in non‐ferroelectric polar BiB3O6 single crystal plates (point symmetry 2) were investigated using X‐ray diffraction technique. The intensity variations of selected Bragg reflections were collected for three different orientations of the applied external electric field vector with respect to the crystal lattice and used for calculating the microscopic structural response of BiB3O6. Due to the limited number of the reflections providing measurable changes in Bragg intensities we restricted ourselves in analyzing the shift of the B3O6 sublattice relative to the Bi one. In addition, we considered the deformation of the Bi‐O, B(1)‐O and B(2)‐O bond lengths and identified the [B(2)O3] group as the most sensitive structural unit to an external electric perturbation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
About 200 years after Mohs – Nanoscratching LiB3O5
Authors: Paufler P. , Shakhverdova I. P. , Bubnova R. S. , Filatov S. K. , Meyer D. C.
Published: October 2008

Though simple scratch hardness tests after Mohs are still used today, the development of diamond nanoscratching equipment offers new possibilities to meet demands of modern nanotechnology. Preceding approaches to assign hardness values to materials are briefly reviewed, and scratch hardness is related to indentation hardness. Taking single‐crystalline LiB3O5 as an example, the dependence of scratch morphology on the direction of scratching is demonstrated quantitatively. The coefficient of friction depends on normal load and varies between 0.25 and 0.37. Moreover, it is oscillating during scratching thus reflecting processes at nanoscale. Dislocation etch pits were observed due to scratching. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase equilibria and prospects of crystal growth in the system LiF–GdF3–LuF3
Authors: dos Santos I. A. , Ranieri I. M. , Klimm D. , Fornari R. , Baldochi S. L.
Published: October 2008

Scheelite type LiGdF4, LiLuF4, and mixtures of both end members were prepared by a hydrofluorination route from the rare earth oxides and commercial LiF. The samples were purified by melting in HF/Ar mixtures, and were investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and energy dispersive X‐ray spectroscopy (EDX) techniques. Both end members show unlimited miscibility in the solid phase. Mixed crystals containing at least 65 mol‐% LiLuF4 melt under direct formation of the liquid phase. The gap between solidus and liquidus is narrow. LiGdF4 and mixed crystals with less then 65 mol‐% LiLuF4 decompose peritectically under formation of (Gd,Lu)F3. Crystal growth is expected to be possible either from Lu‐rich melts with the appropriate scheelite composition or from Gd‐rich melts containing an excess of LiF. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis, crystal structure and vibrational characterization of bis‐μ‐peroxo‐hexacarbonatodicerate(IV) complexes of rubidium and cesium
Authors: Pook N.‐P. , Adam A.
Published: October 2008

The new compounds Rb8[Ce(O2)(CO3)3]2 · 12 H2O (1) and Cs8[Ce(O2)(CO3)3]2 · 10 H2O (2) were obtained from the reaction of hydrogen peroxide and Ce(III) in saturated alkali carbonate solutions. The crystal structures and the unit cell parameters of (1) triclinic, P‐1 with a = 8.973(2) Å, b = 10.815(2) Å, c = 11.130(3) Å, α = 66.992(2)°, β = 68.337(2)°, γ = 74.639(2)°, VEZ = 914.7(4) Å3, Z = 2, and (2) orthorhombic, Pbca, a = 19.3840(16) Å, b = 18.528(2) Å, c = 10.487(3) Å, VEZ = 3766.4(13) Å3, Z = 8, were determined. Both compounds contain the bis‐µ‐peroxo‐hexacarbonatodicerate(IV)‐ion, [(CO3)3Ce(O2)2Ce(CO3)3]8‐. IR and Raman spectra were measured and discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polymorphy of monoclinic terbium triborate, TbB3O6
Authors: Becker P. , Fröhlich R.
Published: October 2008

TbB3O6, that suffers peritectic decomposition below its melting point, was obtained as single crystals by growth from borate flux. Depending on the borate flux, orthorhombic (space group Pnma) TbB3O6 belonging to the isomorphic series of rare earth triborates with small lanthanides, or monoclinic (space group C 2/c) TbB3O6, belonging the corresponding isomorphic series with large lanthanides, was synthesized. Within a broad range at subambient temperatures monoclinic TbB3O6 shows a structural phase transition with a large thermal hysteresis. The phase transition was characterised by means of differential scanning calorimetry, temperature‐dependent polarization microscopy and single‐crystal X‐ray diffraction. According to the observed features the transition can be classified as a non‐ferroic, martensitic phase transformation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New nonlinear‐laser effects in GdVO4 – host‐crystal for Ln3+ lasants
Authors: Kaminskii A. A. , Eichler H. J. , Rhee H.
Published: October 2008

We discovered several new nonlinear‐laser χ(3)‐properties in tetragonal GdVO4 vanadate, which is host‐crystal for lanthanide lasant ions, and attractive gain media for Raman laser converters. We hope that observed many‐phonon SRS, almost two‐octave Stokes and anti‐Stokes lasing comb, cascaded self‐frequency “tripling” and self‐sum‐frequency generation in the blue and UV spectral range could significantly enriche funcional laser potential of this crystal. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Automated analysis of NeuronJ tracing data
Authors: Popko Jonathan , Fernandes Adelaide , Brites Dora , Lanier Lorene M.
Published: October 2008

Studies of neuronal differentiation in vitro often involve tracing and analysis of neurites. NeuronJ (Meijering et al., Cytometry Part A 2004;58A:167–176; http://www.imagescience.org/meijering/software/neuronj/) is a program that can be used for semiautomated tracing of individual neurons; when tracing is completed, a text file containing neurite length measurements is generated. Using cultured hippocampal neurons, we have found that to reach statistical significance it is generally necessary to trace about 100 neurons in each treatment group. Posttracing data analysis requires importing each text file into a statistics program. Analysis of distinct parameters, such as effects of a treatment on axonal versus dendritic branching, requires a great deal of time consuming posttracing data manipulation. We have developed XL_Calculations, a Java‐based program that performs batch analysis on NeuronJ measurement files and automatically makes multiple calculations, including the number, length, and total output (sum length) of primary, secondary, and tertiary neurites on axons and dendrites, and writes the calculations into an Excel worksheet. Batch processing of NeuronJ measurement files dramatically reduces the time required to analyze neuronal morphology. In addition, our program performs more than 45 distinct calculations, enabling detailed determination of treatment effects on neuronal differentiation. Using this program to analyze NeuronJ tracing data, we demonstrate that continuous exposure of differentiating hippocampal neurons to Netrin 1 increases the number of secondary branches on both axons and dendrites, without significantly altering the length of the axon, dendrites, or branches. Similar results were obtained when neurons were grown on poly‐D‐lysine or laminin. © 2008 International Society for Advancement of Cytometry
Performance evaluation of GPON vs EPON for multi‐service access
Authors: Orphanoudakis T. , Leligou H.‐C. , Kosmatos E. , Angelopoulos J. D.
Published: October 2008

Recently both ITU and IEEE have standardized solutions for passive optical networks (PONs) operating at gigabit per second line rates and optimized for the transport of packet‐based traffic to improve the efficiency of previously standardized broadband PONs, which used the ATM cell as the data transport unit. The efficiency and performance of PON systems depend on the transmission convergence layer and mainly on the implemented medium access protocol. Although the latter is not part of the standards and left to the implementer, the standards describe a set of control fields that constitute the tool‐set for the media access control (MAC) operation. Though starting from a common and quite obvious basis, the two standards present significant differences with the legacy of Ethernet marking the IEEE approach, while the emphasis of ITU is on demanding services. In this paper we compare the efficiency and performance of the two systems assuming the implementation of as close as possible MAC protocols. The target is twofold: assess and compare the traffic handling potential of each of the two standards and identify the range of applications they can support. Useful insight can also be gained to the MAC tools that could be designed into the next generation extra large WDM PONs. Copyright © 2008 John Wiley & Sons, Ltd.
A call‐state‐based service triggering algorithm for IMS network
Authors: Liao Jianxin , Xun Zhaoyong , Wang Chun , Zhu Xiaomin
Published: October 2008

To determine the potential signaling traffic reductions, the session establishment procedures were investigated. The investigation showed that the serving call session control function (S‐CSCF) is the major bottleneck in IP multimedia subsystem (IMS) network and the existing third‐generation partnership project (3GPP) service triggering algorithm (3GPP STA) based on initial filter criteria (iFC) increases largely the end‐to‐end session setup delay (SSD). To reduce the SSD and improve the system performance, a call‐state‐based application triggering architecture (CATA) was proposed. In CATA, the call‐state‐based filter criteria and the call‐state‐based service triggering algorithm (CSTA) were proposed, and then the modeling of 3GPP STA and CSTA was presented. Theoretical analysis and simulation results showed that the CSTA avoids the additional signaling traffic load of the S‐CSCF and application server effectively, which exists in 3GPP STA, reduces the SSD considerably, increases the throughput of the S‐CSCF and improves the quality of service of IMS network. Copyright © 2008 John Wiley & Sons, Ltd.
A Combined Gas‐Phase Electron Diffraction/Mass Spectrometric Study of the Sublimation Processes of TeBr4 and TeI4: The Molecular Structure of Tellurium Dibromide and Tellurium Diiodide
Authors: Shlykov Sergey A. , Oberhammer Heinz , Titov Anton V. , Giricheva Nina I. , Girichev Georgiy V.
Published: October 2008

The sublimation processes of TeBr4 at 471(5) K and TeI4 at 373(5) K were studied with a combined gas‐phase electron diffraction and mass spectrometric technique (GED/MS). The mass spectra and the analysis of the GED intensities showed that a contribution of 40(3) mol‐% TeBr2, 59(3) mol‐% Br2, and 1 mol‐% TeBr4 was formed in the vapor over TeBr4(s). Solid tellurium tetraiodide decomposes to form I2(g) and Te(s). A very small contribution of 3.3 ± 2.1 mol‐% of gaseous TeI2 was also determined by both GED and MS. The “metallic” Te accumulated in the solid phase vaporizes at above ca. 670 K as the predominately Te2 molcular species. Refinement of the GED intensities resulted in rg(Te–Br) = 2.480(5) Å and ∠gBr–Te–Br = 99.0(6)° for TeBr2 and rg(Te–I) = 2.693(9) Å and ∠g(I–Te–I) = 103.1(22)° for TeI2. The small contribution of TeBr4 observed in the mass spectra of the vapor over TeBr4 could not be observed in the GED data. Geometric parameters and vibrational frequencies for the tellurium dihalides TeX2 with X = F, Cl, Br, and I were calculated with B3LYP, MP2, CCSD, and CCSD(T) methods by using aug‐cc‐pVTZ basis sets and various core potentials for the tellurium atom. Bonding properties in tellurium dihalides are discussed on the basis of natural bond orbital analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Mononuclear η6‐Arene Complexes of Lanthanides: One‐Step Syntheses, Crystal Structures, and Arene Exchange
Authors: Gorlov Mikhail , Hussami Linda Lejla , Fischer Andreas , Kloo Lars
Published: October 2008

Gallium(III) halides react with cerium(III), ytterbium(III), or dysprosium(III) halides in the presence of alkylated benzenes yielding mononuclear complexes of the general formula [Ln(η6‐arene)(GaX4)3]. The X‐ray structures of [Ce(C6H5Me)(GaCl4)3] (1), [Ce(p‐C6H4Me2)(GaCl4)3]·0.5(p‐C6H4Me2) (2), [Yb(C6H5Me)(GaCl4)3] (3), [Yb(p‐C6H4Me2)(GaCl4)3]·0.5(p‐C6H4Me2) (4), and [Dy(C6H5Me)(GaBr4)3] (5) were determined. Arene ligands in the cerium–toluene compound 1 can be substituted by polycyclic aromatic hydrocarbons (PAHs); the compounds [Ce(naphthalene)(GaCl4)3] (6) and [Ce(pyrene)(GaCl4)3]·0.5(pyrene) (7) have been isolated and structurally characterized. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Iron(III)‐Catalyzed Addition of Benzylic Alcohols to Aryl Alkynes – A New Synthesis of Substituted Aryl Ketones
Authors: Jana Umasish , Biswas Srijit , Maiti Sukhendu
Published: October 2008

A new, efficient and direct addition of benzylic alcohols with terminal aryl alkynes was developed with the inexpensive, non‐toxic, FeCl3 catalyst in nitromethane. The reaction provides a simple method for the synthesis of substituted aryl ketones under mild conditions, and the reaction is highly atom‐economical. Several substituted terminal alkynes underwent smooth reaction with various substituted benzylic alcohols. The electron‐rich alkynes reacted more efficiently and gave higher yields than did the neutral or electron‐deficient alkynes. A wide range of functional groups were tolerated in the developed protocol. The intermediate of this reaction was isolated, and a possible mechanism has been proposed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Enantioselective CpRu‐Catalyzed Carroll Rearrangement – Ligand and Metal Source Importance
Authors: Linder David , Buron Frédéric , Constant Samuel , Lacour Jérôme
Published: October 2008

The addition of unstabilized carbonyl nucleophiles to unsymmetrical allyl‐metal fragments still represents a challenge to generate stereogenic centers enantio‐ and regioselectively. In this context, the decarboxylative Carroll rearrangement of allyl β‐keto esters is particularly interesting, since chiral γ,δ‐unsaturated ketones are obtained. Herein, we show that CpRu half‐sandwich complexes can, with selected enantiopure pyridine‐monooxazoline ligands, catalyze this transformation and afford complete conversions along with good levels of regioselectivity and enantioselectivity. Even more challenging (electron‐poor) substrates react (up to 86 % ee, branched/linear ratio ≥ 97:03). In addition, the use of an air‐stable metal precursor, namely [CpRu(η6‐naphthalene)][PF6], allows the reaction to be carried out reproducibly evenin non‐anhydrous THF with a catalyst loading as low as2 mol‐%. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Seismic design procedure and seismic response of post‐tensioned self‐centering steel frames
Authors: Kim Hyung‐Joon , Christopoulos Constantin
Published: October 2008

Post‐tensioned (PT) self‐centering moment‐resisting frames (MRFs) have recently been developed as an alternative to welded moment frames. The first generation of these systems incorporated yielding energy dissipation mechanisms, whereas more recently, PT self‐centering friction damped (SCFR) moment‐resistant connections have been proposed and experimentally validated. Although all of these systems exhibited good stiffness, strength and ductility properties and stable dissipation of energy under cyclic loading, questions concerning their ultimate response still remained and a complete design methodology to allow engineers to conceive structures using these systems was also needed. In this paper, the mechanics of SCFR frames are first described and a comprehensive design procedure that accounts for the frame behavior and the nonlinear dynamics of self‐centering frames is then elaborated. A strategy for the response of these systems at ultimate deformation stages is then proposed and detailing requirements on the beams in order to achieve this response are outlined. The proposed procedure aims to achieve designs where the interstory drifts for SCFR frames are similar to those of special steel welded moment‐resisting frames (WMRFs). Furthermore, this procedure is adapted from current seismic design practices and can be extended to any other PT self‐centering steel frame system. A six‐story building incorporating WMRFs was designed and a similar building incorporating SCFR frames were re‐designed by the proposed seismic design procedure. Time‐history analyses showed that the maximum interstory drifts and maximum floor accelerations of the SCFR frame were similar to those of the WMRF but that almost zero residual drifts were observed for the SCFR frame. The results obtained from the analyses confirmed the validity of the proposed seismic design procedure, since the peak drift values were similar to those prescribed by the seismic design codes and the SCFR frames achieved the intended performance level under both design and maximum considerable levels of seismic loading. Copyright © 2008 John Wiley & Sons, Ltd.
Numerical calculation of grounding system buried in vertical earth model in low frequency domain based on the boundary element method
Authors: Li Zhong‐Xin , Li Guang‐Fan , Fan Jian‐Bin , Zhang Cui‐Xia
Published: October 2008

To solve a grounding problem which describes a grounding system with floating metallic conductors buried in vertical multilayer earth model under a high voltage a.c. substation, a new mathematical model for accurately computing currents flowing along conductors of the grounding system has been developed in this paper, which is hybrid of Galerkin's type Boundary Element Method and conventional nodal analysis method. Propagation effect of electromagnetic wave within the substation has been neglected due to its limited area. A quasi‐static complex image method and new closed form of Green's function for the vertical multilayer earth model are introduced into this model to accelerate mutual impedance and induction coefficients calculation. The model is then implemented in a computer program, which can be used to calculate currents distribution of any configuration of grounding system, and with or without floating metallic conductors buried in the vertical multilayer earth model. Copyright © 2008 John Wiley & Sons, Ltd.
ML frequency synchronisation for OFDM systems in the presence of overlapped narrow band transmission systems
Authors: Marey Mohamed , Steendam Heidi
Published: October 2008

Spectrum‐overlay scenarios for wideband orthogonal frequency division multiplexing (OFDM) systems bring along new technical challenges that must be considered during the system design. In such a scenario, the receiver has to perform actions, such as channel estimation and synchronisation, in the presence of possibly strong in‐band interference. In this paper, we derive the data‐aided maximum likelihood (ML) fractional frequency estimator in the presence of narrow band interference (NBI) signals. Based on the ML algorithm which has a high complexity, we propose a number of simplifications to develop a lower complexity algorithm. The susceptibility of the simplified estimator to NBI signals is investigated in an analytical way. The analytical results are verified by means of simulations. Although the simplified estimator turns out to be essentially independent of the bandwidth and the location of the interferers, the performance of the estimator is very sensitive to the signal‐to‐interference ratio and the number of interferers. In contrast with the simplified estimator, simulation results indicate that the exact ML estimator is independent of the NBI signals. Copyright © 2008 John Wiley & Sons, Ltd.
Encapsulation and release of menthol. Part 1: the influence of OSAn modification of carriers on the encapsulation of l‐menthol by spray drying
Authors: Mortenson Michael A. , Reineccius Gary A.
Published: October 2008

The objective of this research was to evaluate the effect of octenyl succinic anhydride (OSAn) substitution level of carbohydrate encapsulation matrices on the retention and physical characteristics of spray‐dried l‐menthol microcapsules. It was found that as OSAn substitution of carbohydrates increased, total and surface menthol appeared to increase and decrease, respectively. The particle size of the finished spray‐dried powder was influenced by spray dryer infeed solids concentration, with higher solids leading to larger particle size. Microcapsule density did not appear to be affected by OSAn substitution or carrier type. Copyright © 2008 John Wiley & Sons, Ltd.
A short asymmetric synthesis of massoialactone
Authors: Yoshikawa Keisuke , Kitahara Takeshi
Published: October 2008

(R)‐(−)‐Massoialactone (1) was synthesized via the enantioselective aldol‐type reaction of diketene (2) with (E)‐2‐hexenal (4) in only a few steps. Copyright © 2008 John Wiley & Sons, Ltd.
Quantitation in gas chromatography: usual practices and performances of a response factor database
Authors: Cicchetti Esmeralda , Merle Philippe , Chaintreau Alain
Published: October 2008

In this study, usual methods commonly applied to report the quantitative composition of flavours, fragrances and essential oils were compared. The MS determinations without response factors exhibited a lack of accuracy and reproducibility. FID provided better results, but the determinations were still unsatisfactory. The best results were obtained by true internal standardization in MS and FID, which is time‐consuming for mixtures composed of many constituents. The use of a response factor database was thus proposed and validated by testing the response dependence on GC parameters, using an experimental design. Very low time variations were observed. Under standard GC conditions, the determination of a model mixture with four different instruments exhibited a mean bias of < 3.4%. Copyright © 2008 John Wiley & Sons, Ltd.
Multicomponent dissipative particle dynamics: Formulation of a general framework for simulations of complex fluids
Authors: Chaudhri Anuj , Lukes Jennifer R.
Published: October 2008

The dissipative particle dynamics mesoscopic simulation method is analyzed thoroughly by identifying the scaling factors necessary to simulate a multicomponent system. A new framework of general expressions is derived relating the parameters in the system to their dimensionless quantities. The consistent non‐dimensionalization used in this paper serves to connect the previous models in the literature. When the scaling factors are based on the solvent in a multicomponent system, the system of equations reduces to the well‐known Groot and Warren model. Validation results for ideal, simple and binary immiscible fluids are presented and compared with established results from the literature. The framework established herein is an important step toward the practical application of dissipative particle dynamics for the analysis of complex fluid systems. Copyright © 2008 John Wiley & Sons, Ltd.
Geometrical interpretation of the multi‐point flux approximation L‐method
Authors: Cao Yufei , Helmig Rainer , Wohlmuth Barbara I.
Published: October 2008

In this paper, we first investigate the influence of different Dirichlet boundary discretizations on the convergence rate of the multi‐point flux approximation (MPFA) L‐method by the numerical comparisons between the MPFA O‐ and L‐method, and show how important it is for this new method to handle Dirichlet boundary conditions in a suitable way. A new Dirichlet boundary strategy is proposed, which in some sense can well recover the superconvergence rate of the normal velocity. In the second part of the work, the MPFA L‐method with homogeneous media is studied. A systematic concept and geometrical interpretations of the L‐method are given and illustrated, which yield more insight into the L‐method. Finally, we apply the MPFA L‐method for two‐phase flow in porous media on different quadrilateral grids and compare its numerical results for the pressure and saturation with the results of the two‐point flux approximation method. Copyright © 2008 John Wiley & Sons, Ltd.
Drag reduction by flow separation control on a car after body
Authors: Rouméas Mathieu , Gilliéron Patrick , Kourta Azeddine
Published: October 2008

New development constraints prompted by new pollutant emissions and fuel consumption standards (Corporate Average Economy Fuel) require that automobile manufacturers develop new flow control devices capable of reducing the aerodynamic drag of motor vehicles. The solutions envisaged must have a negligible impact on the vehicle geometry. In this context, flow control by continuous suction is seen as a promising alternative. The control configurations identified during a previous 2D numerical analysis are adapted for this purpose and are tested on a 3D geometry. A local suction system located on the upper part of the rear window is capable of eliminating the rear window separation on simplified fastback car geometry. Aerodynamic drag reductions close to 17% have been obtained. Copyright © 2008 John Wiley & Sons, Ltd.
Use of benzodiazepines, depressive symptoms and cognitive function in old age
Authors: van Vliet Peter , van der Mast Roos C. , van den Broek Marianne , Westendorp Rudi G. J. , de Craen Anton J.M.
Published: October 2008

Objective

Benzodiazepine use is more frequently observed in depressive and cognitively impaired subjects. The temporal relation behind this association is unknown. Here, we studied whether benzodiazepine use is associated with depressive symptoms and cognitive function and what the temporal relation underlying the associations is.

Methods

Within the Leiden 85‐plus Study, a prospective population based study of 599 subjects aged 85 years at baseline, we assessed benzodiazepine use, depressive symptoms, and cognitive function annually during a 5‐year follow‐up period.

Results

Benzodiazepine users were more likely to be female, be institutionalized, and have a low education. Benzodiazepine users scored 0.76 points higher on the 15‐item Geriatric Depression Scale than non‐users (95% CI: 0.27–1.25, p = 0.002). They were 1.6‐fold more likely to develop new depressive symptoms in 1 year when compared to non‐users (95% CI: 1.05–2.55, p = 0.028). Benzodiazepine use did not associate with cognitive function, but discontinued benzodiazepine users had a 4.0 points lower Mini Mental State Examination (MMSE) score in the year before discontinuation than continued benzodiazepine users (95% CI: 1.31–6.73, p = 0.004).

Conclusions

In old age the use of benzodiazepines is associated with depressive symptoms and the use of benzodiazepines may precede the development of depressive symptoms. Treating physicians seem to be aware of the detrimental effects of benzodiazepines on cognitive function. However, they should be cautious in prescribing a new benzodiazepine in old age and monitor elderly benzodiazepine users for development of depressive symptoms. Copyright © 2008 John Wiley & Sons, Ltd.
Altered sleep brain functional connectivity in acutely depressed patients
Authors: Leistedt Samuël J.J. , Coumans Nathalie , Dumont Martine , Lanquart Jean‐Pol , Stam Cornelis J. , Linkowski Paul
Published: October 2008

Recent evidence suggests that problems in information processing within neural networks may underlie depressive disease. In this study, we investigated whether sleep functional brain networks are abnormally organized during a major depressive episode (MDE). We characterized spatial patterns of functional connectivity by computing the “synchronization likelihood” (SL) of 19 sleep EEG channels in 11 acutely depressed patients [42 (20–51) years] and 14 healthy controls [32.9 (27–42) years]. To test whether disrupting an optimal pattern [“small‐world network” (SWN)] of functional brain connectivity underlies MDE, graph theoretical measures were then applied to the resulting synchronization matrices, and a clustering coefficient (C, measure of local connectedness) and a shortest path length (L, measure of overall network integration) were determined. In the depressed group, the mean SL was lower in the delta, theta and sigma frequency bands. Acutely depressed patients showed a significantly lower path length in the theta and delta frequency bands, whereas the cluster coefficient showed no significant changes. The present study provides further support that sleep functional brain networks exhibit “small‐world” properties. Sleep neuronal functional networks in depressed patients are characterized by a functional reorganization with a lower mean level of global synchronization and loss of SWN characteristics. These results argue for considering an MDE as a problem of neuronal network organization and a problem of information processing. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.
Condensation enhancement on a vertical plate (1st report, heat transfer characteristic on a dispersed finned surface)
Authors: Chu Rencai , Hatanaka Tsutomu , Nishio Shigefumi
Published: October 2008

In this study, a condensation heat transfer experiment on vertical continuous and dispersed finned surfaces using FC5312 was carried out. Experimental parameters were the pitch and height of the fin, and the dispersed fin length. In the results, the phenomena of condensate retention were observed in the bottom of each row of the dispersed fin. The condensate flow from the upper row was concentrated into the valley of the fin and then flowed down into the valley of the next fin. Moreover, it was found from the experiment that the heat transfer coefficient on the dispersed finned surface was lower than the one on the continuous finned surface as the fin pitch was smaller, but was larger than that of the continued finned surface for a larger fin pitch. Furthermore, the heat transfer enhancing effect became more significant for the higher fin with the larger fin pitch, and the heat transfer reducing effect became more significant for the lower fin with the smaller fin pitch. These special characteristics of condensation mentioned above were caused by the phenomena of condensate retention in each row of the fin and the flow pattern of the condensate between two adjacent fins on the dispersed finned surface based on experimental observations. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20221
Molecular dynamics study for dissociation phenomena of a gas molecule on a metal surface
Authors: Tokumasu Takashi , Hara Kanako , Ito Daigo
Published: October 2008

The dissociation phenomena of a gas molecule on a metal surface were analyzed by the molecular dynamics method. A platinum (111) surface and hydrogen were chosen as the metal surface and the gas molecule, respectively. The embedded atom method was used as the interaction between atoms in order to express the dependence of electron density. The parameters were determined so that the results such as the electron density, adsorption energy of an H atom on a Pt(111) surface, and the interaction between H atoms of an H2 molecule obtained by the EAM method were consistent with those obtained by the density functional theory or empirical function. Collisions between a hydrogen molecule and the platinum surface were simulated by the molecular dynamics method, and the dissociation probability was obtained. Using these results, the effect of the motion of the surface atoms or the hydrogen molecule on the dissociation probability was analyzed. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20222