bluuebunny/crossref_metadata_2025 huggingface dataset:
EPR of Cu2+ in lithium tetraborate single crystals
Authors: Corradi G. , Watterich A. , Polgár K. , Nagirnyi V. , Hofstaetter A. , Rakitina L. G. , Meyer M.
Published: March 2007

A low temperature electron paramagnetic resonance study of single crystals of the scintillator and thermoluminescent dosimeter material lithium tetraborate (Li2B4O7) doped by Cu has been carried out. The observed spectra of an unpaired hole with strong d ‐character and characteristic hyperfine splittings can be ascribed to Cu2+ situated at or near the Li lattice site, which supports the conclusions of a parallel luminescence study about the low symmetry of emitting Cu+ sites. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The thermostimulated exoelectron emission of NaF:U,Me compounds after electron beam irradiation
Authors: Kidibaev M. M. , Dzholdoshov B. K. , Koroleva T. S. , Slesarev A. I. , Shulgin B. V. , Ivanov V. Yu. , Tcherepanov A. N. , Pedrini Ch. , Lebbou K.
Published: March 2007

The thermostimulated exoelectron emission (TSEE) of NaF:(U,Me) compounds after electron beam irradiation in the 300–800 K temperature range has been investigated. For NaF:(U,Me) bulk, fiber and nanocrystals several regular peaks of TSEE have been found. Additional effects with the sign of thermostimulated explosive electron emission have been found too. The nature of TSEE process is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
VUV 5d – 4f luminescence of Gd3+ doped into CaF2
Authors: Makhov V. N. , Batygov S. Kh. , Dmitruk L. N. , Kirm M. , Stryganyuk G. , Zimmerer G.
Published: March 2007

High‐resolution (∼1 Å) emission and excitation spectra as well as luminescence decay kinetics have been studied for CaF2 doped with Gd3+(0.1%) and Ce3+(0.05%) under excitation by synchrotron radiation near and above the edge of interconfigurational 4f7 – 4f65d transitions in Gd3+ and 4f – 5d transitions in Ce3+. The fast (τ ∼ 8.5 ns) VUV luminescence has been detected from the crystal the spectrum of which shows zero‐phonon line at 77660 cm–1 and dominating vibronic line at energy interval ∼370 cm–1. The vibronic structure in VUV emission spectrum well correlates with that observed at the onset of the Gd3+ 4f7 – 4f65d excitation spectrum. The obtained results confirm that the VUV luminescence observed in CaF2:Gd3+,Ce3+ originates from 4f65d – 4f7 radiative transitions in Gd3+. The vibronic structure in emission and excitation spectra of Gd3+ d – f luminescence from the CaF2:Gd3+,Ce3+ crystal differs from that observed for other trivalent rare earth ions doped into CaF2 indicating that Gd3+ ions reside in sites of different type in CaF2 than that of tetragonal (C4v) symmetry. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Neutron, ion and electron induced defects in activated LiF and NaF single crystals
Authors: Shulgin B. V. , Ivanov V. Yu. , Tcherepanov A. N. , Petrov V. L. , Anipko A. V. , Neshov F. G. , Kidibaev M. M. , Koroleva T. S. , Solomonov V. I. , Kaigorodova O. A.
Published: March 2007

The neutron induced defects in activated LiF and NaF single crystals have been investigated by studying the absorption and luminescence spectra. For LiF and NaF neutron irradiated crystals the creation of F, F2 and F3+ aggregate color centers have been analysed in comparison with F, F2 and F3+‐center production in NaF crystals irradiated by ion and electron beams. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of coloured LiF crystals with given content of oxygen, hydroxyl and metal impurities
Authors: Baldacchini G. , Goncharova O. , Kalinov V. S. , Montereali R. M. , Nichelatti E. , Vincenti A. , Voitovich A. P.
Published: March 2007

Optical absorption and emission spectra have been studied in LiF crystals containing oxygen, hydroxyl and metal impurities, and coloured with γ ‐rays at room temperature with doses up to 83 kGy. Well‐defined bands in absorption and emission spectra of uncoloured samples have been attributed to impurities. Colouring of the same crystals adds new spectroscopic features, which are related to various colour centres, but at the same time depends strongly on the impurity content, especially as far as their formation efficiency is concerned. The connection between impurities and colour centres will be discussed on the basis of optical spectra of uncoloured and coloured, and also pre‐annealed and bleached crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dependence of long‐lived defect creation on excitation density in MgO single crystals
Authors: Lushchik Aleksandr , Kärner Tiit , Lushchik Cheslav , Vasil'chenko Eugene , Dolgov Sergei , Issahanyan Vigen , Liblik Peeter
Published: March 2007

The processes of the creation, stabilization and annealing of anion Frenkel defects have been investigated in MgO and MgO:Be single crystals irradiated by α particles, uranium swift ions or fast neutrons at 300 K and also additionally irradiated by 5 keV electrons at 6 K. Neutral oxygen interstitials undergo stabilization due to their association with the holes localized near Be2+ ions or near cation vacancies. The peculiarities of the processes of nonimpact creation and stabilization of point defects under conditions of a high density of electronic excitations formed in the tracks of swift heavy ions have been considered by the example of MgO crystals, where the creation energy of a pair of long‐lived Frenkel defects exceeds the energy gap, EFD > Eg. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitation processes of the blue luminescence in crystalline SiO2 probed by synchrotron radiation measurements
Authors: Cannas Marco , Agnello Simonpietro , Boscaino Roberto , Gelardi Franco Mario , Trukhin Anatoly
Published: March 2007

Luminescence properties of crystalline α‐quartz were investigated by time‐resolved spectroscopy under pulsed synchrotron radiation excitation in the vacuum ultraviolet range. Our results evidence that two emission bands overlap at 2.7 eV, both being observed only at low temperature. The first contribution is excited by band‐to‐band transition and is related to the radiative recombination of a self trapped exciton occurring in a time scale of a few ms, the second is associated with defects induced in quartz by γ‐ and β‐radiation, is excited at 7.6 eV and its lifetime is 3.6 ns at T = 10 K. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The role of Pb2+ ions in the luminescence of LuAG:Ce single crystalline films
Authors: Babin V. , Gorbenko V. , Makhov A. , Nikl M. , Zazubovich S. , Zorenko Y.
Published: March 2007

Steady‐state and time‐resolved emission and excitation spectra and luminescence decay kinetics were studied at 4.2‐350 K under excitation in the 2.5‐15 eV energy range for the undoped and Ce3+‐doped Lu3Al5O12 (LuAG) single crystalline films grown by Liquid Phase Epitaxy method. The spectral bands arising from the single Pb2+‐based centers were identified. Competition between Pb2+ and Ce3+ ions in the processes of energy transfer from the LuAG crystal lattice was evidenced. Due to overlap of the 3.61 eV emission band of Pb2+ centers with the 3.6 eV absorption band of Ce3+ centers, an effective energy transfer from Pb2+ ions to Ce3+ ions occurs, resulting in the appearance of slower component in the luminescence decay kinetics of Ce3+ centers and decrease of the Ce3+‐related luminescence intensity. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Decay course of slow emission component for thallium and lead centers in some alkali halide crystals
Authors: Polák K. , Mihóková E. , Schulman L. S.
Published: March 2007

We discuss some of our results on KCl and KBr crystals doped with very low concentration of Pb2+ and Tl+ ions. The aim is to understand validity of two theoretical models developed to explain an anomaly of some slow luminescence components. Low doping concentration follows an effort to suppress any parasitic effects on the measured decay curve. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flight to Mars and radiation defects in Li2B4O7 and KTiOPO4 crystals
Authors: Grachev V. , Malovichko G. , Pankratov V. , Rust T. , Burak Ya.
Published: March 2007

Solar, space, laser and nuclear reactor radiations lead to the appearance of defects in complex oxides and to inevitable performance degradation of devices based on these materials. Since many radiation defects are paramagnetic ones, the electron paramagnetic resonance, EPR is one of the most suitable method for their study. Results of optical and EPR study of defects in as grown and irradiated Li2B4O7 and KTiOPO4 crystals are presented. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optically‐detected magnetic resonance of molecular color centers CO3– and NO3 in gamma‐irradiated beryl
Authors: Pinheiro M. V. B. , Krambrock K. , Guedes K. J. , Spaeth J.‐M.
Published: March 2007

In this paper we identify, with optically‐detected magnetic resonance via the magnetic circular dichroism of the absorption, the NO3 and CO3– molecular radicals trapped in the structural channels of gamma‐irradiated beryl. We confirm that, along with the CO3–, the NO3 is also responsible for the blue color by introducing several absorption peaks between 14500 cm–1 and 18000 cm–1 (720 nm down to 540 nm). Their individual contributions to the overall many‐peak optical spectra have been established and most of the transitions could be explained in terms of a combination of crystal‐field and spin‐orbit split 2A2′ → 2E′ transition plus vibronic replicas. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Intrinsic luminescence and energy transfer processes in pure and doped YVO4 crystals
Authors: Pankratov V. , Grigorjeva L. , Millers D. , Yochum H. M.
Published: March 2007

Luminescence properties of nominally pure and neodymium doped YVO4 single crystals have been studied by means of time‐resolved luminescence spectroscopy technique. It was detected that, besides the main well‐known blue excitonic emission band near 2.8 eV, an additional UV emission band at ∼3.1 eV appears in the spectra of intrinsic luminescence at low temperatures (∼80 K) for all crystals studied. Decay time of the UV band is much faster in comparison with the blue one and the UV band is quenched at temperatures above 150 K. Origin of the UV emission band is discussed. A significant rise front was observed in the relaxation kinetics of Nd3+ emission under band‐to‐band excitation. The time constant of the rise front of the Nd3+ emission is very close to decay time of the blue emission in a wide temperature range. It is suggested that the energy transfer process from the host lattice to neodymium ions occurs via excitonic states. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Colloidal copper in soda‐lime silicate glasses characterised by optical and structural methods
Authors: Macalik B. , Krajczyk L. , Morawska‐Kowal T.
Published: March 2007

Optical and structural characteristics of phase separated soda lime silicate glasses doped with monovalent copper have been studied for samples exchanged in molten copper chloride and afterwards thermally treated in a gaseous hydrogen atmosphere. The created colloidal particles are of different size, and their diameter increases with the penetration depth of the copper ions, which in turn depends on the chemical and thermal treatment. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of MgO ceramics irradiated in different reactors
Authors: Kvatchadze V. , Dekanozishvili G. , Kalabegishvili T. , Vylet V. , Galustashvili M. , Akhvlediani Z. , Keratishvili N. , Zardiashvili D. , Sobolevskaia S.
Published: March 2007

High‐temperature thermo‐stimulated luminescence (TSL) of translucent ceramic material MgO:0.2 weight% LiF has been studied in order to determine whether it can be used to estimate the fast neutron fluences. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ab initio calculation of wurtzite‐type GaN nanowires
Authors: Gulans Andris , Tale Ivars
Published: March 2007

Ab initio calculations of wurtzite‐type GaN nanowires have been performed using density functional theory. Different shapes of nanowires of with similar diameters of around 2 nm have been considered to determine the stability of the structures. The quantitative similarities in the local properties obtained and dangling bond energies of nanowires and bulk surfaces have lead to a simple model model for a calculation of effective Young's modulus of nanowires of arbitrary diameters and shapes. The size dependence of the Young's modulus reveals a softening of GaN nanowires with the decrease of the diameter. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy transfer and excitation processes in thin films of rare‐earth organic complexes for NIR emission
Authors: Pietrantoni S. , Francini R. , Pizzoferrato R. , Penna S. , Paolesse R. , Mandoj F.
Published: March 2007

We have synthesized and studied the excitation‐emission properties of three erbium‐coordinating porphyrin‐based complexes for solid state films with emission in the 1530‐nm band. In two of these complexes the C‐H groups of the organic part (ligand) have been substituted with C‐F and/or C‐Br ones in order to assess the role of the deactivation by the vibronic levels in the strong quenching of NIR emission. Time‐resolved phosphorescence measurements have also been carried out in gadolinium analogues to verify the influence of substitution on the singlet‐triplet intersystem crossing processes. The observed increase in the NIR emission is not consistent with the complete removal of quenching and the presence of other mechanisms for deactivation should be investigated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dosimetric characterization of wollastonite‐teflon composites
Authors: Souza Divanizia N. , Melo Adeilson P. , Oliveira Maria G. , Caldas Linda V. E.
Published: March 2007

In this work, the thermoluminescent properties of pellets containing powdered Wollastonite embedded in Teflon were studied. The preliminary results using gamma rays from a 60Co source showed linearity at the calibration curve between 0.5 Gy and 10 Gy. The main TL peaks are located at 125, 200 and 245 °C. The repeatibility of TL response presented a maximum coefficient of variation of 6.3%. The material can be used in successive irradiation‐reading‐annealing cycles without an appreciable change in its sensitivity. The calibration curve for a gamma source (60Co) up to 20 kGy and the minimum detection limits were obtained. The results show that these Wollastonite‐Teflon pellets present possibilities for use as TL dosimeters. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of transition metal ion‐doped MgAl2O4 spinel for laser application
Authors: Jouini Anis , Yoshikawa Akira , Brenier Alain , Fukuda Tsuguo , Boulon Georges
Published: March 2007

Ti and Mn‐doped MgAl2O4 spinel have been successfully grown by the micro‐pulling‐down method and spectroscopic properties have been investigated in view of the potential use as a short‐wavelength tunable solid‐state laser. Strong blue emission is observed from Ti‐doped MgAl2O4 and green emission from a Mn‐doped one. The optimum conditions to obtain the strongest emission were studied by changing the doping concentration. These two broad emission bands around 455 nm for Ti (decay time of 5.7 µs) and 518 nm for Mn (decay time of 6.11 ms) were obtained by pumping in the UV region at 266 nm and 355 nm, respectively. Discussion is submitted to assign the origins of each type of fluorescence in spinel. Ni2+‐doped crystal exhibits a broad absorption band at around 980 nm suitable for InGaAs laser diode pumping and a broad emission band in the near infrared with two decay times at 210 µs and 850 µs respectively and high quantum yields. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
What may be expected from the “microwave resonant cavity technique” applied to rare‐earth‐doped insulating materials?
Authors: Loudyi H. , Guyot Y. , Kazanskii S. A. , Gâcon J.‐C. , Pédrini C. , Joubert M.‐F.
Published: March 2007

The principle of measurements using the “microwave resonant cavity technique” applied to rare‐earth‐doped insulating materials is reviewed and the physical nature of the expected signals is discussed. Experimental results concerning both single crystal and powdered samples of Lu2SiO5: Ce3+ are presented and discussed as typical examples. From measurements at various temperatures between 300 and 5 K and under different pulsed laser beam powers, it is shown that detailed information on the rare earth photoionization process, photoconductivity dynamics and trapping effects may be gained, in addition to photoconductivity spectra. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of ferroelectric nanopowders by EPR method
Authors: Slipenyuk A. M. , Kondakova I. V. , Glinchuk M. D. , Laguta V. V.
Published: March 2007

BaTiO3 nanopowders with different particle sizes have been studied by Electron Paramagnetic Resonance method over a temperature range covering the ferroelectric‐paraelectric transition. Iron and manganese impurities were used as probes for these experiments. The evolution of the spectra over the transition was observed through 1) the change in symmetry of Fe3+ from tetragonal to cubic and 2) the appearance beyond TC of Mn2+ characteristic lines. The results were analyzed according to a theoretical model proposed by one of the authors to extract the distribution of the particles size from the electron paramagnetic resonance spectra. Both the mean particle radius R0 and the dispersion σ showed a very good agreement with the data obtained from direct measurement of the size distribution. This evidences both the critical influence of the nanoparticles sizes distribution on the EPR spectra's main features and on the temperature dependence of the polarization. In the framework of the theoretical model proposed by one of the authors the distribution of the particles size was extracted from the electron paramagnetic resonance spectra. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermoluminescence study of cerium‐doped lanthanum halides
Authors: Sellès O. , Fasoli M. , Vedda A. , Martini M. , Gourier D.
Published: March 2007

Point defects and impurities play a major role in optical properties of scintillators, as they can be at the origin of afterglow emission, which are detrimental for the applications. Spectrally‐resolved thermally stimulated luminescence (TSL) is used here to study defects possibly affecting scintillation properties of LaCl3:Ce and LaBr3:Ce samples grown by Saint‐Gobain Crystals & Detectors. In the case of LaCl3:Ce, after X‐ray irradiation two major glow peaks with complex structures are detected at 23 K and 63 K (when measured at a heating rate of 0.1 K/s). A more composite structure of the TSL pattern of LaBr3:Ce is observed. Possible explanations and implications of these findings are discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Oxide and nitride protective layers on stainless steel studied by AES, WDS and XPS
Authors: Mandrino Djordje , Lamut Martin , Godec Matjaž , Torkar Matjaž , Jenko Monika
Published: March 2007

Protective surface layers on AISI 321 stainless steel were prepared by thermal treatments at two different temperatures in air and two controlled atmospheres. Different oxide and/or nitride layers were formed. Surface morphology of the layers was investigated by scanning electron microscopy (SEM). Auger electron spectroscopy (AES) depth profiling of the samples was performed. Since depth profiling suggested layer thicknesses of the order of hundreds of nanometres, an attempt was made to obtain some fast, averaged information about the layer compositions using wavelength dispersive spectroscopy (WDS) at two different beam energies to obtain probing depths best suited to the layer thickness. X‐ray photoelectron spectroscopy (XPS) profiling of one layer was also performed to obtain information about the chemical states of the elements inside the layer. The analysed samples showed considerable differences with respect to their surface morphology, oxide/nitride layer thicknesses, compositions and layer–metal interface thickness. Copyright © 2007 John Wiley & Sons, Ltd.
Network structure and innovation: The leveraging of a dual network as a distinctive relational capability
Authors: Capaldo Antonio
Published: March 2007

This paper employs comparative longitudinal case study research to investigate why and how strong dyadic interfirm ties and two alternative network architectures (a ‘strong ties network’ and a ‘dual network’) impact the innovative capability of the lead firm in an alliance network. I answer these intrinsically cross‐level research questions by examining how three design‐intensive furnishings manufacturers managed their networks of joint‐design alliances with consulting industrial design firms over more than 30 years. Initially, in order to explore the sample lead firms' alliance behavior, I advance an operationalization of interorganizational tie strength. Next, I unveil the strengths of strong ties and the weaknesses of a strong ties network. Finally, I show that the ability to integrate a large periphery of heterogeneous weak ties and a core of strong ties is a distinctive lead firm's relational capability, one that provides fertile ground for leading firms in knowledge‐intensive alliance networks to gain competitive advantages whose sustainability is primarily based on the dynamic innovative capability resulting from leveraging a dual network architecture. Copyright © 2007 John Wiley & Sons, Ltd.
Three Novel Mixed‐ligand Cadmium(II) Sulfonates with Aza‐aromatic Skeltons as Co‐ligands
Authors: Yang En‐Cui , Dai Pei‐Xia , Wang Xiu‐Guang , Ding Bin , Zhao Xiao‐Jun
Published: March 2007

To survey the influence of aza‐aromatic co‐ligands on the structure of Cadmium(II) sulfonates, three Cd(II) complexes with mixed‐ligand, [CdII(ANS)2(phen)2] (1), [CdII(ANS)2(2,2′‐bipy)2] (2) and [CdII(ANS)2(4,4′‐bipy)2]n (3) (ANS = 2‐aminonaphthalene‐1‐sulfonate; phen = 1,10‐phenanthroline; 2,2′‐bipy = 2,2′‐bipyridine; 4,4′‐bipy = 4,4′‐bipyridine) were synthesized by hydrothermal methods and structurally characterized by elemental analyses, IR spectra, and single crystal X‐ray diffraction. Of the three complexes, ANS consistently coordinates to Cd2+ ion as a monodentate ligand. While phen in 1 and 2,2′‐bipy in 2 act as N,N‐bidentate chelating ligands, leading to the formation of a discrete mononuclear unit; 4,4′‐bipy in 3 bridges two CdII atoms in bis‐monodentate fashion to produce a 2‐D layered network, suggesting that the conjugate skeleton and the binding site of the co‐ligands have a moderate effect on molecular structure, crystal stacking pattern, and intramolecular weak interactions. In addition, the three complexes exhibit similar luminescent emissions originate from the transitions between the energy levels of sulfonate anions.
On the Interchange Ability of the N‐donor Position in the Rare Earth Coordination Polymers $^{1}_{\infty}\rm [Ln(Btz)_{3}(L)]$, L = BtzH, Ph(NH2)2, NH3, and Pyridine
Authors: Müller‐Buschbaum Klaus , Mokaddem Yassin
Published: March 2007

Benzotriazolates of the rare earth elements form chain like coordination polymers of the formula $^{1}_{\infty}\rm [Ln(Btz)_{3}(L)]$. An additional neutral ligand L saturates the coordination spheres of the trivalent lanthanide ions and, depending on the reaction conditions, can be a varying donor (L = BtzH, Ph(NH2)2, NH3 and Py). Reactions in the BtzH (1H‐benzotriazole) melt result in coordination of benzotriazole and its thermal decomposition products as L. We have now investigated if the site occupied by L can be exchanged with other N donor ligands. Pyridine can substitute BtzH, Ph(NH2)2 and NH3 under solvothermal conditions giving the coordination polymer $^{1}_{\infty}\rm [Ln(Btz)_{3}(Py)]$ even for the biggest LnIII cation lanthanum without changing the overall strand structure. Chains proof to be the chemically favoured and stable structure fragment with the L position being the chemically variable site.
Synthesis, Structure and Raman Data of the New Binuclear Zirconium Complex [Ph4P]2[(ZrCl4Py)2O], with a Zr‐O‐Zr Bridge
Authors: Chen Hao‐Hong , Zhao Jing‐Tai , Siefert Ralf , Peppel Tim , Köckerling Martin
Published: March 2007

The new Zirconium(IV) coordination compound [Ph4P]2[(ZrCl4Py)2O] (Ph = phenyl, Py = pyridine) was synthesized by dissolving ZrCl4, [Ph4P]Cl and a stoichiometric amount of NaOH/Na mixture in pyridine or pyridine/organic solvent mixtures. The title phase was obtained as colourless crystals. The crystal structure of [Ph4P]2[(ZrCl4Py)2O] was determined. It crystallizes monoclinic, P21/c, Z = 4, a = 13.412(2), b = 13.461(2), c = 16.442(3) Å, β = 102.72(1)°. The structure consists of isolated tetraphenylphosphonium cations and [(ZrCl4Py)2O]2− complex anions. The centrosymmetric complex anion contains a linear Zr–O–Zr bridge. Each Zr atom is coordinated by one oxygen dianion, the N atom of one pyridine ring and four chloro ligands in a distorted octahedral geometry. The Raman spectrum of [Ph4P]2[(ZrCl4Py)2O] is also reported. Most of the observed frequencies can be assigned to vibrations of the tetraphenylphosphonium cations and the pyridine rings.
Phosphino[tris(trimethylsilyl)methyl]Boranes and 2,4‐Bis[tris(trimethylsilyl)methyl]‐1,3,2,4‐diphosphadiboretanes [1]
Authors: Jetzfellner R. , Nöth H. , Paine R. T.
Published: March 2007

The reaction of tris(trimethylsilyl)methylboron dihalides (Me3Si)3CBX2 (X = Cl, F) with the lithium phosphides LiPHtBu and LiPHmes leads to the phosphinoboranes (Me3Si)3CBX‐(PHR), (Me3Si)3CB(PHR)2 or the 1,3,2,4‐diphosphadiboretanes [(Me3Si)3CB(PR)]2, depending on the ratio of the reagents, the reaction temperature and concentration. High dilution and low temperatures are required for the synthesis of (Me3Si)3CB(Hal)PHR (1–3) in order to prevent the formation of (Me3Si)3CB(PHR)2 (4 and 5). The latter compounds are best prepared in a two step phosphination from (Me3Si)3CBHal2 and LiPHR. At higher temperatures the four‐membered 1,3,2,4‐diphosphadiboretanes [(Me3Si)3CB(PR)]2 6 and 7 are the most stable compounds. On the other hand, compounds of type (Me3Si)3CB(Hal)PR2, 8 and 9, are thermally more stable than the monophosphinoboranes 1–3. Phosphinoboranes of type (Me3Si)3CB(PR2)2 (R = tBu, mes) could not be prepared. NMR and mass spectral data are in accord with the monomeric nature of compounds 1 to 9.
[{Na(7‐Nitro‐5‐sulfonate‐naphthalene‐1,4‐dicarboxy‐acid (H2O)2}·H2O]n: A Water‐Soluble 2D Layer Polymeric Complex with Microporous Molecular Channels
Authors: Wu Rui‐Feng , Zhang Tong‐Lai , Qiao Xiao‐Jing , Zhang Jian‐Guo , Yang Li , Wang Shao‐Zong
Published: March 2007

The X‐ray crystallographic studies are reported for a water‐soluble sodium complex of organic acid, {[Na(NSNDC)(H2O)2]·H2O}n, (NSNDC = 7‐Nitro‐5‐sulfonate‐napthalene‐1,4‐dicarboxy‐acid). It contains layers of vertically oriented NNSDC‐anions sandwiching cations and water molecules. The rows of anions are linked in a direction by sodium ions and along b by hydrogen bonding, which have microporous channels (9.410 × 3.210Å2) along the crystallographic b‐axis. Considering the Na coordination environments, π‐π stacking interaction between aryl ring and hydrogen bonds, the title compound represents a stably 2D infinitely extended structure.
Nickel(I)‐Komplexe mit 1,1′‐Bis(phosphino)ferrocenen als Liganden
Authors: Langer Jens , Fischer Reinald , Görls Helmar , Theyssen Nils , Walther Dirk
Published: March 2007

Nickel(I) Complexes with 1,1′‐Bis(phosphino)ferrocenes as Ligands

The thermically stable monomeric Nickel(I) complexes [(dtbpf)Ni(acac)] (1) and [(dippf)NiCl] (2) were synthesized and characterized by elemental analyses, EPR spectroscopy, and by X‐ray crystal structure analyses of single crystals (dtbpf: 1,1′‐bis(di‐tertbutylphosphino)ferrocene; dippf: 1,1′‐bis(diisopropylphosphino)ferrocene). 1 is formed by reduction of Ni(acac)2 with triethylaluminium in the presence of dtbpf, together with the nickel(0) complex [(dtbpf)Ni(C2H4)]. 1 contains a NiI atom surrounded of two O‐ and two P donor atoms in a distorted tetrahedral coordination. 2 was obtained by reduction of [(dippf)NiCl2] with NaBH4. In 2 the nickel(I) atom adopts trigonal planar coordination.
Synthese, Struktur, Elektrochemie und optische Eigenschaften von alkinylfunktionalisierten 1,3,2‐Diazaborolen und 1,3,2‐Diazaborolidinen
Authors: Weber L. , Penner A. , Domke I. , Stammler H.‐G. , Neumann B.
Published: March 2007

Syntheses, Structures, Electrochemistry and Optical Properties of Alkyne‐Functionalized 1,3,2‐Diazaboroles and 1,3,2‐Diazaborolidenes

The reaction of 2‐bromo‐1,3‐ditert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborole (3) with lithiated tert‐butyl‐acetylene and lithiated phenylacetylene affords the 2‐alkynyl‐functionalized 1,3,2‐diazaboroles 4 and 5 as a thermolabile colorless oil (4) or a solid (5). Similarly 2‐bromo‐1,3‐diethyl‐2,3‐dihydro‐1H‐1,3,2‐benzodiazaborole (6) was converted into the crystalline 2‐alkynyl‐benzo‐1,3,2‐diazaboroles 7 and 8 by treatment with LiC≡C–tBu or LiC≡CPh, respectively. 2‐Ethynyl‐1,3‐ditert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborole (2) was metalated with tert‐butyl‐lithium and subsequently coupled with 2‐bromo‐1,3,‐ditert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborole (3) to afford bis(1,3‐ditert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazaborol‐2‐yl)acetylene (9) as thermolabile colorless crystals. Analogously coupling of the lithiated species with 6 or with 2‐bromo‐1,3‐ditert‐butyl‐1,3,2‐diazaborolidine (11) gave the unsymmetrically substituted acetylenes 10 or 12, respectively, as colorless solids. Compounds 4, 5, 7–10 and 12 are characterized by elemental analyses and spectroscopy (IR, 1H‐, 11B{1H}, 13C{1H}‐NMR, MS). The molecular structures of 5, 8 and 9 were elucidated by X‐ray diffraction analyses.
Preparation and Crystal Structures of Ruthenium and Osmium Oxide Tetrahalides
Authors: Shorafa Hashem , Seppelt Konrad
Published: March 2007

RuOF4 as the highest valence oxide fluoride exist as a molecular compound (a = 606.0(1), b = 836.1(1), c = 626.3(1) pm, β = 91.637(3), Z = 4; P21/n) as well as fluorine bridged polymer (a = 547.7(2), b = 928.5(3), c = 1252.4(3) pm, Z = 8, P212121). A reproducible method for pure, deep blue OsOF4 is given. Pure OsOF4‐I is isostructural to the fluorine bridged polymeric RuOF4 (a = 554.6(1), b = 955.4(2), c = 1278.4(2), Z = 8, P212121). OsOF4‐II is also a fluorine bridged polymer (a = 537.8(2), b = 1274.8(4), c = 555.2(2), β = 117.716(6)°, Z = 4, P21/c). OsOCl4 again is a molecular species (a = 938.9(2), b = 561.3(1), c = 1192.0(2), β = 109.944(4)°, Z = 4, P21/c).
Das reduzierte Nitridosilicat BaSi6N8
Authors: Stadler Florian , Schnick Wolfgang
Published: March 2007

The Reduced Nitridosilicate BaSi6N8

The reduced nitridosilicate BaSi6N8has been synthesized starting from barium nitride and silicon diimide in a radio‐frequency furnace at temperatures of about 1650 °C. The structure has been determined from X‐ray powder diffraction data and was refined by the Rietveld method (Imm2 (no. 44),a= 793.16(1),b= 934.37(2),c= 483.57(1) pm,V= 358.38(1) ·106pm3,Z= 2,wRp= 0.0353,Rp= 0.0238,RF2= 0.0660, 452 observed reflections, 42 parameters). BaSi6N8crystallizes isotypically with SrSi6N8. The three‐dimensional Si‐N‐network consists of corner‐sharing SiN4tetrahedra and single bonds Si‐Si forming N3Si‐SiN3building units.29Si solid‐state NMR spectra of BaSi6N8resemble those of SrSi6N8exhibiting two resonances at δ = −54.3 and −28.0 ppm. Their observed intensity ratio of approximately 2 : 1 can be attributed to theSiN4tetrahedra and theSi2N6units, respectively. This observation is in accordance with the results from the X‐ray structure determination (Si at Wyckoff positions 8e(SiN4) and 4d(Si2N6)).
Polyfluoroorganoboron‐Oxygen Compounds. 5 Feasible Routes to Perfluoroalkyltrimethoxyborates M[CnF2n+1B(OMe)3] (n ≥ 3)
Authors: Adonin Nicolay Yu. , Bardin Vadim V. , Frohn Hermann‐Josef
Published: March 2007

A well applicable preparative method for lithium perfluoroalkyltrimethoxyborates, Li[CnF2n+1B(OMe)3] (n = 3, 4, 6), was elaborated which is based on the reaction of B(OMe)3 with CnF2n+1Li generated from CnF2n+1H and t‐BuLi. Alternative perfluoroalkylation reactions of B(OMe)3 with perfluoropropyllithium generated from C3F7I and RLi, perfluoropropylmagnesium bromide, or perfluoropropyltrimethylsilane and potassium fluoride gave less satisfactory results for M[C3F7B(OMe)3]. The conversion of M[CnF2n+1B(OMe)3] salts (M = Li, BrMg) into K[CnF2n+1B(OMe)3] salts and basic properties of the new salts are reported.
O‐Triorganosilyl Carbamoselenoates – Synthesis and Reactions
Authors: Ibi Kazumasa , Kawai Kohji , Kato Shinzi , Ando Fumio , Koketsu Jugo
Published: March 2007

A series of O‐triorganosilyl carbamoselenoates were isolated in good yields from the reaction of sodium or potassium carbamoselenoates with triorganosilyl chlorides. The O‐silyl carbamoselenoates readily reacted with RbF and CsF and with organo‐germanium, ‐tin, and ‐lead halides and gave the corresponding heavy alkali metal and Se‐substituted Group 14 organometal and carbamoselenoates in moderate to good yields.
Synthesis and some Reactions of Alkali Metal Carbamotelluroates
Authors: Ibi Kazumasa , Imase Tomohiro , Kato Shinzi , Ando Fumio , Koketsu Jugo
Published: March 2007

Sodium and potassium carbamotelluroates [M(R2NCOTe), M = Na, K, Rb, Cs] were synthesized in moderate to good yields by reacting carbamoyl chloride with the corresponding alkali metal tellurides. The salts readily reacted with trimethylsilyl chloride to form O‐trimethylsilyl carbamotelluroate (R2NCTeOSiMe3), which further reacted with RbF and CsF to lead to the corresponding heavy alkali metal carbamotelluroates. These salts reacted with alkyl iodide and carbamoyl chlorides to give the corresponding Te‐alkyl carbamotelluroates and dicarbamoyl tellurides in moderate yields.
The Structure of Tetrakis(pentafluorophenyl)tellurium(IV), Te(C6F5)4
Authors: Naumann Dieter , Tyrra Wieland , Fischer Hendrik T. M. , Kremer Silke
Published: March 2007

Tetrakis(pentafluorophenyl)tellurium(IV), Te(C6F5)4, was prepared from the reaction of TeCl4 and Mg(C6F5)Br. Crystallization of the crude product from n‐pentane at −25 °C gave suitable single crystals. The title compound crystallizes in the monoclinic space group P21/c (Z = 8) with two independent molecules per unit cell.
Solvothermal Synthesis and Structures of Lamellar [Mn(tren)2]Cl2 and the Dimeric and Polymeric Hexaselenidomanganese(II) Complexes [{Mn(Se6)(tren)}2] and $^{2}_{\infty}\rm [\{Mn(Se_{6})(tren)\}]$
Authors: Kromm Anna , Sheldrick William S.
Published: March 2007

Reaction of [MnCl2(tren)] with tren (tris‐(2‐aminoethyl)amine) affords the coordination polymer $^{2}_{\infty}\rm [Mn(tren)_{2}]Cl_{2}$ (1), in which the primary amino groups of tridentate tren ligands connect [(tren)Mn]2+ fragments into a pseudo 63 network. The Mn atoms exhibit a capped octahedral environment with the tertiary N atom of the second tetradentate tren ligand in the capping position. Treatment of MnCl2 with Se at 1:2 molar ratio in H2O/tren (10:1) at 150 °C leads to formation of the dinuclear complex [{Mn(μ‐Se6)(tren)}2] (2), which contains tetradentate tren ligands and two bridging hexaselenide ligands in the 1κSe1 : 2κSe6 mode. In contrast, reaction of [MnCl2(tren)] with Se at a 1:6 molar ratio under similar sovothermal conditions affords the isomeric coordination polymer $^{2}_{\infty}\rm [Mn(\mu-Se_{6})(tren)]$ (3). In this complex, Se62− anions now bridge [(tren)Mn]2+ fragments into chains, that themselves are linked into polymeric sheets through one of the primary amino groups of the tetradentate tren ligands.
A New Two‐Dimensional Coordination Polymer of Mercury(II) with very High Thermal Stability
Authors: Mahmoudi Ghodrat , Morsali Ali , Zhu Long‐Guan
Published: March 2007

A 2D HgII coordination polymer containing ligands 1,2,4‐triazole (Htrz) and thiocyanate, [Hg(μ3‐trz)(SCN)]n (1) has been synthesized and characterized by elemental analysis and IR spectroscopy. The single‐crystal X‐ray data show the coordination number of Hg atoms is four and the ligand trz− acts as a three‐fold donor. The thermal stability of compound 1 was studied by thermal gravimetric and differential thermal analyses. The composition and formation of the complex in methanol solution were found to be in support of its solid state structure.
Relationship Between Apolipoprotein Concentrations and HDL Subclasses Distribution
Authors: Tian Li , Fu Mingde , Jia Lianqun , Xu Yanhua , Long Shiyin , Tian Haoming , Tian Ying
Published: March 2007

Alterations in plasma apolipoproteins levels can influence the composition, content, and distribution of plasma lipoproteins that affect the risk of atherosclerosis. This study assessed the relationship between plasma apolipoproteins levels, mainly apoAI, and HDL subclass distribution. The contents of plasma HDL subclasses were determined by two‐dimensional gel electrophoresis coupled with immunodetection in 545 Chinese subjects. Compared with a low apoAI group, the contents of all HDL subclasses increased significantly both in middle and high apoAI group, and the contents of large‐sized HDL2b increased more significantly relative to those of small‐sized preβ1‐HDL in a high apoAI group. When apoAI and HDL‐C levels increased simultaneously, in comparison to a low apoAI along with HDL‐C concentration group, a significant increase (116%) was shown in HDL2b but only a slight increase (26%) in preβ1‐HDL. In addition, Pearson correlation analysis revealed that apoAI levels were positively and significantly correlated with all HDL subclasses. Multiple liner regression demonstrated that the apoAI concentrations were the most powerful predictor for HDL subclass distribution. With the elevation of apoAI concentrations, the contents of all HDL subclasses increased successively and significantly, especially, an increase in large‐sized HDL2b. Further, when apoAI and HDL‐C concentrations increased simultaneously, the shift to larger HDL size was more obvious. Which, in turn, indicated that HDL maturation might be enhanced and, the reverse cholesterol transport might be strengthened along with apoAI levels which might be a more powerful factor influencing the distribution of HDL subclasses.
REJECTIONIST ISLAMISM IN SAUDI ARABIA: THE STORY OF JUHAYMAN AL-ʿUTAYBI REVISITED
Authors: Hegghammer Thomas , Lacroix Stéphane
Published: March 2007

The storming of the Mecca mosque by Juhayman al-ʿUtaybi and his fellow rebels in November 1979 represents one of the most spectacular events in the modern history of Saudi Arabia. Yet, it is one of the least understood. Even decades after the event, many important questions remain unanswered. Who were the rebels, and what did they want? Why and how did Juhayman's group come into existence? What happened with the rebels and their ideas after the Mecca events? This article seeks to shed light on the story and legacy of Juhayman al-ʿUtaybi with new information gathered from extensive fieldwork in Saudi Arabia and elsewhere.
A Cairo Court Register
Authors: HANNA NELLY
Published: March 2007

People mentioned in court records tend to be anonymous, but Ja'far Pasha is known from several different sources: his biography in al-Muhibbi's Khulasat al-athar shows him to be a man of learning and a successful military leader Dutch East India Company records mention him as Ottoman pasha in Yemen from 1607 to 1616 and Egyptian historical sources place him in 1617 or 1618 as governor of Egypt, where he died of the plague which bears his name (fasl Ja'far). The above court case sheds light on Ja'far Pasha's economic dealings, indicating that he was doing business in Egypt years before being appointed governor.
ALTERNATIVE APPROACHES TO MODERNIZATION IN THE LATE OTTOMAN PERIOD: İZMİRLİ İSMAİ L HAKKI'S RELIGIOUS THOUGHT AGAINST MATERIALIST SCIENTISM
Authors: Özervarli M. Sait
Published: March 2007

This article examines the views and place of Izmirli Ismail HakkÄ± in late Ottoman thought. A prominent religious thinker, HakkÄ± took part in lively debates in Istanbul. He and other moderate religious thinkers were against the defenders of mere positivism in the process of modernization of Ottoman thought in the modern period. By focusing on HakkÄ±, the article aims to highlight the significance of central Ottoman scholars in modern Islamic thought and the debates of modernization. It pays special attention to HakkÄ±'s attempt to reconstruct Islamic philosophical theology with a new kalam book and to his critical responses to 19th–century materialist thought, as well as to his opinions regarding other Ottoman reform projects.
YOKSULLUK VE VATANDAŞLIK : CUMHURIYET TÜRKIYE ‘SINDEKI SOSYAL POLITIKA ORTAMINA GENEL BIR BAKIŞ
Authors: Bugra Ayse
Published: March 2007

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REJECTIONIST ISLAMISM IN SAUDI ARABIA: THE STORY OF JUHAYMAN AL-'UTAYBI REVISITED
Authors: Hegghammer Thomas , Lacroix Stéphane
Published: March 2007

Please open the PDF to view the article.
Sphere–wall collisions: vortex dynamics and stability
Authors: THOMPSON MARK C. , LEWEKE THOMAS , HOURIGAN KERRY
Published: March 2007

For moderate Reynolds numbers, a sphere colliding with a wall in the normal direction will lead to a trailing recirculating wake, threading over the sphere after impact and developing into a complex vortex-ring system as it interacts with vorticity generated at the wall. The primary vortex ring, consisting of the vorticity from the wake of the sphere prior to impact, persists and convects, relatively slowly, outwards away from the sphere owing to the motion induced from its image. The outward motion is arrested only a short distance from the axis because of the strong interaction with the secondary vorticity. In this paper, the structure and evolution of this combined vortex system, consisting of a strong compact primary vortex ring surrounded by and interacting with the secondary vorticity, is quantified through a combined experimental and numerical study. The Reynolds-number range investigated is (100 < Re < 2000). At Reynolds numbers higher than about 1000, a non-axisymmetric instability develops, leading to rapid distortion of the ring system. The growth of the instability does not continue indefinitely, because of the dissipative nature of the flow system; it appears to reach a peak when the wake vorticity first forms a clean primary vortex ring. A comparison of the wavelength, growth rate and perturbation fields predicted from both linear stability theory and direct simulations, together with theoretical predictions, indicates that the dominant physical mechanism for the observed non-axisymmetric instability is centrifugal in nature. The maximum growth occurs at the edge of the primary vortex core, where the vorticity changes sign. Notably, this is a physical mechanism different from that proposed previously to explain the development of the three-dimensional flow of an isolated vortex ring striking a wall.
Near-critical hydraulic flows in two-layer fluids
Authors: KLUWICK ALFRED , SCHEICHL STEFAN , COX EDWARD A.
Published: March 2007

This paper deals with the propagation of nearly resonant gravity waves in two-layer flows over a bottom topography assuming that both fluids are incompressible and inviscid. Evolution equations are derived for weakly nonlinear surface-layer and internal-layer waves in the hydraulic limit of infinite wavelength. Special emphasis is placed on the flow regime where the quadratic nonlinear parameter associated with internal-layer waves is small or vanishes. For example, this is the case for all possible density ratios if the velocities in both layers are equal and if the interface height is close to one-half the total fluid-layer height. The waves then exhibit so-called mixed nonlinearity leading in turn to the formation of positive and negative hydraulic jumps. Considerations based on a model equation for the internal dissipative–dispersive structure of hydraulic jumps indicate that the admissibility of discontinuities in this regime depends strongly on the relative magnitudes of dispersion and dissipation. Surprisingly, these admissible hydraulic jumps may violate the wave-speed-ordering relationship which requires that the upstream wave speed does not exceed the propagation speed of the discontinuity. An important example is provided by the inviscid hydraulic jump, which has been known for some time, although its non-classical nature, in that it transmits rather than absorbs waves, has apparently not been recognized before.
Propagation and stability of vorticity–entropy waves in a non-uniform flow
Authors: ATASSI O. V.
Published: March 2007

The evolution of disturbances in an annular duct with a non-isentropic radially varying mean flow is studied. Linear and nonlinear analyses are carried out to examine how the mean velocity and density gradients affect the stability and coupling between the disturbances. To isolate the effect of the mean-velocity gradients from that of the mean-density gradients two mean flows are considered, one with a Gaussian density profile and a uniform axial velocity and the other with Gaussian density and Gaussian axial-velocity distributions. For small-amplitude disturbances with the former mean flow profile, the vortical disturbances convect with the mean flow and density fluctuations grow linearly in space as a result of the interaction of the mean-density gradient with the disturbance radial velocity. Eigenmode analysis of the latter profile shows that unstable modes with exponential growth occur owing to the inflection point in the mean-velocity profile. These modes are almost independent of the mean-density profile and are most unstable for low azimuthal wavenumbers. Nonlinear solutions support the linear results and show an algebraic growth of the density for a range of azimuthal wavenumbers and both uniform and non-uniform mean-velocity profiles. The growth of the velocity fluctuations, however, is strongly dependent on the azimuthal wavenumber of the incident disturbance and the mean-velocity profile. The largest growth in the disturbance is observed at radial locations where the largest mean-flow gradients exist. Owing to the growth of the density fluctuations, coupled vorticity–entropy waves are observed downstream of a forced harmonic excitation in a non-isentropic flow. The forcing amplitudes of the incident waves were varied to see how the solutions change with amplitude. As the amplitude is increased, the waves continue to grow and a steepening of the gradients is observed as they propagate downstream until eventually very sharp density and velocity fronts form. These results show that the mean-flow and density profiles play an important role in the evolution of low-azimuthal-wavenumber disturbances which can couple strongly to the duct acoustic modes during combustion instabilities.
Water-wave scattering by a semi-infinite periodic array of arbitrary bodies
Authors: PETER MALTE A. , MEYLAN MICHAEL H.
Published: March 2007

We consider the scattering by a semi-infinite array of bodies of arbitrary geometry excited by an incident wave in the linear water-wave formulation (which reduces to the simpler case of Helmholtz scattering if the depth dependence can be removed). The theory presented here is extremely general, and we present example calculations for an array of floating elastic plates (a highly non-trivial scatterer). The solution method follows closely from the solution for point scatterers in a medium governed by Helmholtz's equation. We have made several extensions to this theory, considering water-wave scattering, allowing for bodies of arbitrary scattering geometry and showing how to include the effects of bound waves (called Rayleigh–Bloch waves in the water-wave context) in the formulation. We present results for scattering by arrays of cylinders that show the convergence of our methods and also some results for the case of scattering by floating elastic plates and fixed docks.