bluuebunny/crossref_metadata_2025_split huggingface dataset:
The proper use of indices of metamerism
Authors: Berns Roy S. 
Published: October 2008

AbstractGeneral (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

AbstractElectrophilic 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

AbstractPhenomena 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

AbstractIn 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

AbstractNew 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

AbstractSingle‐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

AbstractFor 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

AbstractThough 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

AbstractScheelite 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

AbstractThe 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

AbstractTbB3O6, 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

AbstractWe 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

AbstractStudies 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

AbstractRecently 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

AbstractTo 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

AbstractThe 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

AbstractGallium(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

AbstractA 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

AbstractThe 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)