bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric properties of Li doped Li‐Nb‐O thin films
Authors: Perentzis G. , Horopanitis E. E. , Papadimitriou L. , Ďurman V. , Šály V. , Packa J.
Published: March 2007

Lithium niobate LiNbO3 was prepared as a thin film layered structure deposited on stainless steel substrate using e‐gun evaporation. The Li doping was provided for by the formation of Li‐Nb‐O/Li/LiNb‐O sandwich structure and annealing at about 250 °C. AC impedance spectroscopy measurements were performed on the samples at temperatures from the interval between 28 and 165 °C and in a frequency range of 10–3 to 106 Hz. Using the values Z ′ and Z ″ at different frequencies, the dielectric parameters – parts of the complex permittivity ϵ′ and ϵ″ and loss tangent tan δ were calculated. The results prove validity of the proposed equivalent circuit containing parallel RC elements connected in series where the first RC element represents the bulk of material and the second RC element belongs to the double layer at the metal interface. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Measurements of the low frequency dispersion in electrical grade ceramics
Authors: Ďurman V. , Packa J. , Lelák J. , Šály V.
Published: March 2007

The paper reports on the advanced technique of the dielectric response and conductivity calculation based on the recovery voltage measurements. The new calculation method has been developed and applied to assessment of an electrical grade ceramics made from quartz and alumina porcelain. The measured data were converted into the form of complex permittivity. Experimental results show the existence of the polarization process with relaxation frequency of about 0.001 Hz. The relaxation frequency and the conductivity appear to be very sensitive to the temperature variation. They could be prospective indicators of the changes generated by temperature and ageing of material. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
EPR hyperfine structure of F‐type centres in pure LiBaF3 crystal
Authors: Fedotovs A. , Elsts E. , Rogulis U. , Gulans A. , Tale I. , Nikl M. , Ichinose N. , Shimamura K.
Published: March 2007

We studied EPR spectra of pure LiBaF3 sample of high quality. For EPR measurements LiBaF3 sample was X‐irradiated at room temperature, however spectra could be observed at low temperatures ‐ at 77 K. All hyperfine structure lines of F‐type centre could be well resolved contrary to our earlier studies of Fe doped LiBaF3 crystal. Qualitative analysis with g‐tensor parameters derived from magneto‐optical measurements showed that the F‐type centre observed earlier by MCD‐EPR techniques is the same F‐type centre we observe with the EPR. We analyse origin of the hyperfine structure of the EPR spectra and their angular dependencies and discuss the structure of F‐type centres in the LiBaF3 crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling irradiation induced metastability in ceramic thin films
Authors: Ossi Paolo M.
Published: March 2007

Amorphous, or crystalline phase nucleation in ion bombarded ceramic films is analysed by the Interface Migration‐Charge Transfer (IMCT) atomistic model. The development of a dense collision cascade leads to enrichment of one of film constituents at the cascade‐crystal interface, where non‐equilibrium profiles both of composition and of electronic density result. Local charge transfer reactions (CTR) simulate system relaxation via formation of dimers of an effective compound. We calculate the energy cost and the enthalpy change to produce one such dimer for a representative set of binary and ternary irradiated compounds. Threshold values of both quantities separate amorphised from crystalline compounds under ion bombardment. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and optical defects in LiNbO3 crystals induced by femtosecond laser irradiation
Authors: Galinetto P. , Grando D. , Mozzati M. C. , Ballarini D. , Giulotto E.
Published: March 2007

Microstructural modifications, induced by femtosecond laser irradiation on Lithium Niobate (LN) crystals were investigated by means of optical microscopy and micro‐Raman spectroscopy. Commercial z‐cut congruent LN substrates were irradiated with focused ultra‐short laser pulses at 810 nm. At the focus region either structural changes or material removal were observed by varying the irradiation conditions. The mapping of Raman spectrum revealed the insurgence of Raman modes, which are forbidden in the used scattering geometry. This phenomenon increases gradually by approaching the ablation region. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Luminescence of Ce‐doped borate‐oxyfluoride glass ceramics
Authors: Dimitrocenko L. , Rogulis U. , Veispals A. , Springis M. , Kulis P. , Fedotovs A. , Mishnev A.
Published: March 2007

In the present work we studied the possibility to obtain oxyfluoride glass ceramics based on a lithium and potassium borate glasses with addition of fluorides. Lithium‐borate glasses without lanthanum fluoride are transparent up to 275 nm. In samples with LaF3 doped with Ce‐activator, an additional absorption at about 300 nm and intense photoluminescence could be observed. Ce‐doped potassium‐borate glass with addition of fluorides LaF3, LiF and GdF3 was milky and not transparent, an intense photoluminescence has been observed, X‐ray diffraction measurements showed a presence of well‐pronounced crystalline phases of LiF as well as of GdBO3. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The dose dependence and the firing effects on the thermoluminescence of quartz
Authors: Halperin Abraham
Published: March 2007

Papers on the dose dependence of thermoluminescence of quartz have been published in recent years by research groups from various countries. These papers show that untreated quartz gives very strong superlinearity (up to slopes of 3 in a log‐log scale). Almost all the investigators who describe the above effects refer to a theoretical paper by Kristianpoller et al. (J. Phys. D: Appl. Phys. 7, 1063 (1974) [6]) which shows that adding a competing trap to the energy system of quartz, gives a set of equations which can be solved numerically for various sets of given parameters, when results explain all the above effects. Unlike other investigators who used quartz powders, we preferred to use single crystals of quartz. For better resolution of two or more neighboring thermoluminescence peaks, we reduced the rate of heating in the thermoluminescence measurements to 10 degrees per minute. We found that limiting the temperature in the TL heatings during the set of doses to 400‐450 K, gave extremely high superlinearity (slopes close to 7). A set of decreasing doses was found to reduce the high superlinearity and to increase the 430 K peak by more than 3 orders of magnitude without any firing. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Intrinsic defect processes in bixbyite sesquioxides
Authors: Chroneos A. , Levy M. R. , Stanek C. R. , McClellan K. , Grimes R. W.
Published: March 2007

Atomic scale simulation techniques have been employed to study the intrinsic defect processes of a range of bixbyite sesquioxides using a transferable set of interatomic potentials. The efficacy of the approach is demonstrated through comparison of the predictions to previous experimental and theoretical (density functional theory) results. The aim here is to provide data that can be used as a basis for further structural optimizations targeting the use of mixed bixbyite sesquioxides as buffer layers for the fabrication of epitaxically coated, high‐temperature superconductors on different substrates. The internal energies for the three possible intrinsic defect reactions (Schottky, cation Frenkel and oxygen Frenkel) have been calculated with regard to the application of these oxides for scintillator radiation detectors. The lowest energy intrinsic process is the oxygen Frenkel for all the bixbyite sesquioxides considered. Surprisingly, the oxygen Frenkel energy does not depend greatly on the host cation radius. The implication of this result is that the lowest energy intrinsic defect occurs on the oxygen sublattice and therefore will be most likely to serve as electron and hole traps. These traps are important for the scintillation properties of bixbyite sesquioxides as they act as non‐radiative centers reducing the efficiency of scintillator materials. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural study of NaNO2 embedded into porous glass
Authors: Rysiakiewicz‐Pasek E. , Maczka M. , Urbanowicz A.
Published: March 2007

Temperature‐dependent Raman study of NaNO2 confined within porous glass with a pore size of 46 nm has been performed. It is demonstrated that the bandwidths and frequencies of the Raman bands as a function of temperature show similar behaviour, but not identical, as those observed for bulk NaNO2. This result indicates that the first‐order phase transition mechanism is only slightly modified by embedding NaNO2 into the porous glass. It seems that formation of “premelted state” is not significant in the studied material, at least up to 40‐50 K above Tc. At higher temperatures, however, a significant increase of bandwidth of the 1326 cm–1 band is observed, which could indicate appearance of “premelted” state. The dielectric measurements are consistent with this view since they show large increase of dielectric permittivity above 480 K, well below the NaNO2 melting temperature (554 K). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Native and radiation‐induced two‐fold coordinated sites in nanostructured SnO2:SiO2
Authors: Brovelli S. , Chiodini N. , Lauria A. , Meinardi F. , Paleari A.
Published: March 2007

Radiation‐induced spectral modifications of the 5 eV excited photoluminescence (PL) of oxygen vacancies have been found in a nanostructured silica‐based material. This system, made up of SnO2 nanocrystals embedded in amorphous SiO2, is generated by nano‐clustering in oversaturated Sn‐doped silica produced by sol‐gel method. Treatment in oxygen‐poor atmosphere introduces oxygen deficiency in the glassy host and a photo‐reactive SnO‐like interphase at the SnO2 nanocrystal surface. PL measurements initially show native PL activity at 2.7 eV excited at 5 eV, ascribable to oxygen vacancies in intrinsic two‐fold coordinated Si sites. Prolonged UV irradiation at 4.7 eV (fourth harmonic of Nd‐YAG pulsed laser) gives rise to extrinsic PL activity at 3.1 eV, ascribable to Sn‐variant of oxygen vacancy. The results suggest that the UV irradiation causes a progressive release of Sn from the nanophase surface to the glassy network in oxygen vacancy sites. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Damage creation in LiF and NaCl crystals irradiated with swift heavy ions at 8 and 300 K
Authors: Schwartz K. , Lang M. , Neumann R. , Sorokin M. V. , Trautmann C. , Volkov A. E. , Voss K.‐O.
Published: March 2007

Single crystals of LiF and NaCl were irradiated at 8 and 300 K with different ions (12C to 238U) of MeV‐GeV energy in the electronic stopping regime. The ion‐induced damage was studied by optical absorption, thermo‐stimulated luminescence, and scanning force microscopy. The concentration of the color centers depends on the energy loss of the ions. In both crystals, the irradiation with heavy ions (Au, Pb, U) results in a higher F center concentration at 8 K than at 300 K; for light ions (C, Ti, Ni) the opposite effect takes place. The observed results can be explained by ion induced local heating. Contrary to color‐center creation, the formation of nano‐sized surface hillocks does not depend on the irradiation temperature. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studies of the location of precious metals in nanocrystalline titanium dioxide using XRD and XANES
Authors: Rammutla K. E. , Savin S. L. P. , Matshaba M. G. , Chadwick A. V. , Ngoepe P. E.
Published: March 2007

Au, Ag, Pt and Pd doped TiO2 nanocrystals were prepared using sol‐gel routes. X‐ray Near Edge Structure (XANES) was used to study the location of these precious metal dopants in nanocrystalline TiO2. The effects of these dopants on the phase transformation and grain growth were investigated using X‐ray diffraction (XRD). Two dopant concentrations i.e. 1 and 5% were studied and similar results were found. Silver and Palladium initially form oxides but annealing at high temperatures converts them to metals. Gold and and silver do not affect the anatase ‐ rutile transformation temperature whereas palladium and platinum do. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The peculiarities of hydroxyl impurity behaviour in crystalline LiF and MgO matrices under the action of radiation
Authors: Akhvlediani Z. , Kvatchadze V.
Published: March 2007

The comparative analysis of the results obtained in the investigation of infrared absorption spectra of irradiated lithium fluoride and magnesium oxide samples has been made. For irradiation of the samples X‐ray generator, Co60 source and different reactors were used. The universal linear dependence of bands caused by centers containing OH– ions was observed for the first time in the irradiated MgO samples. The thermal treatment of irradiated LiF crystals have clearly showed the interconnection of hydroxyl ions and hydrogen products of their dissociation.The significant difference in the behaviour of impurity hydroxyl ions in matrices of the mentioned ionic compounds was observed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of TiO2–SiO2glass over a wide spectral range
Authors: Smith D. Y. , Black C. E. , Homes C. C. , Shiles E.
Published: March 2007

Optical properties of vitreous SiO2with 7.4 wt.% TiO2are found by dispersion analysis of reflectivity measured in the infrared, visible, and ultraviolet augmented with literature values of vacuum‐ultraviolet reflectivity and absorption. The principal infrared absorption associated with the titanium dopant occurs at 950 cm−1in a deep minimum of the host silica absorption. We attribute this to a perturbation of the silica's absorption at 1076 cm−1involving oxygen atoms bridging SiO4and TiO4tetrahedra. Strong ultraviolet absorptions of Ti4+occur just below the silica exciton peak between 5.5 and 7.8 eV. We attribute these to charge‐transfer transitions at TiO4tetrahedra; i.e., bound excitons consisting of a Ti3+ion and a hole shared by four oxygen neighbours. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Luminescence of oxygen related defects in zirconia nanocrystals
Authors: Smits K. , Grigorjeva L. , Łojkowski W. , Fidelus J. D.
Published: March 2007

The luminescence of undoped tetragonal structure ZrO2 nanocrystals was studied. The luminescence intensity depends on oxygen content in gases mixture in which the nanocrystals were annealed. The distorted Zr‐O bond is suggested to be the recombination center for band carriers. The oxygen deficient defect is proposed to be responsible for photoluminescence. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Li‐ion conducting organic‐inorganic hybrid electrolytes derived from TEOS and methacrylates
Authors: Zelazowska E. , Borczuch‐Laczka M. , Rysiakiewicz‐Pasek E.
Published: March 2007

Li‐ion conductive organic‐inorganic hybrid electrolytes with the ionic conductivities of 10–3 ‐ 10–2 Scm–1 have been prepared by sol‐gel route from tetraethyl orthosilicate TEOS, poly(ethylene oxide), ethyl methacrylate, ethylene glycol dimethacrylate, butyl methacrylate, organic solvents and lithium perchlorate (0.01 wt%). The results of morphology and structure investigation by scanning electron microscopy equipped with energy dispersive X‐ray spectroscopy (SEM/EDX), Fourier Transform Infrared Spectroscopy and 29Si MAS Nuclear Magnetic Resonance have revealed strong influence of organic modifications, resulted in direct chemical bonds between organic and inorganic components and poly‐condensation process overlapped with crosslinking polymerization in hybrids prepared with ethyl methacrylate. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermoluminescent characteristics of Actinolite‐Teflon composites for gamma high‐doses
Authors: Melo Adeilson P. , Valerio Mário E. G. , Caldas Linda V. E.
Published: March 2007

In this work a preliminary study of the thermoluminescent (TL) dosimetric properties of the Brazilian actinolite:Ca2(Mg,Fe)5(Si8O22)(OH)2 (silicate of the Jade family) was undertaken for gamma high‐doses. Actinolite occurs in several regions in the world. In this work actinolite in the form of rude mineral from Governador Valadares, Minas Gerais, Brazil, was studied. The natural actinolite samples were powdered, and the selected grains were mixed with Teflon in the proportion 2(Teflon):1(Actinolite). The mixture was pressed and sintered for production of pellets of composites Actinolite ‐ Teflon. The glow curves present two peaks at 125 °C and 210 °C. The TL response reproducibility presents a maximum variation coefficient of 4.8%. The calibration curve is linear between 0.5 Gy and 1 kGy for pellets irradiated with gamma radiation (60Co) and between 0.5 Gy and 10 Gy for pellets irradiated with X‐rays (33 keV). The TL response presents an energy dependence of 26% for X‐rays between 27 and 41 keV. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Irradiation effects in BaF2:CuCl2 and BaF2:Mn,Ce crystals
Authors: Kristianpoller N. , Chen W. , Weiss D. , Kuzmin D. , Chen R.
Published: March 2007

Effects of X, β and VUV radiation were studied in BaF2:CuCl2 and BaF2:Mn,Ce crystals. Methods of optical absorption and of luminescence were applied; X‐luminescence (XL), photoluminescence (PL), thermoluminescence (TL), photo‐transferred TL (PTTL) and optically stimulated luminescence (OSL) as well as emission and excitation spectra were measured. Optical stimulation for PTTL and OSL investigations was carried out at liquid nitrogen temperature (LNT) in samples that had previously been X or β irradiated at room temperature (RT) and the results were compared to those obtained in nominally pure BaF2 crystals. The TL excitation spectra showed maxima at the long‐wavelength side of the first exciton band. In the VUV induced TL, some of the peaks appeared at the same temperature as in the X‐induced TL, indicating that the same radiation‐induced traps were created by the different types of radiation. The TL efficiency of some of the crystals was found to be of the same order of magnitude as that of the known TL dosimetric material LiF:Mg,Ti (TLD 100). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Luminescence characteristics of the LPE‐grown undoped and In‐doped ZnO thin films and bulk single crystals
Authors: Pejchal J. , Kagamitani Y. , Ehrentraut D. , Sato H. , Odaka H. , Hatanaka H. , Nikl M. , Yoshikawa A. , Fukumura H. , Fukuda T.
Published: March 2007

The time‐resolved emission spectroscopy using the fs‐laser pulse and ps X‐ray excitations was employed to compare the luminescence characteristics of the liquid phase epitaxy grown ZnO films and the hydrothermally grown single crystals. Reabsorption of the excitonic emission is demonstrated in the bulk ZnO. In the In‐doped films the donor‐acceptor pair recombination luminescence was evidenced above 400 nm and its decay was found to obey the t–1 law. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Time development of scintillating response in Ce‐ or Pr‐doped crystals
Authors: Mares J. A. , Beitlerova A. , Nikl M. , Vedda A. , D'Ambrosio C. , Blazek K. , Nejezchleb K.
Published: March 2007

Time development of a Nphels/MeV photoelectron yield of various Ce and Pr‐doped inorganic crystals (mainly garnets, perovskites and silicates) was studied in detail. Slow scintillation decay components influence time dependence, especially at those scintillators containing Lu as lattice ions where an increase of Nphels per 1 MeV in the time span 0.25–5 µs is more than 50%. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High resolution spectroscopic properties and emission decay of rare‐earth doped transparent laser ceramics
Authors: Lupei V. , Lupei A. , Ikesue A.
Published: March 2007

The paper discusses the use of high‐resolution spectroscopy and emission decay for investigation of the variety, nature, structure and distribution of the centers formed by the rare earth ions in transparent polycrystalline ceramics of cubic oxide laser materials (garnets and sesquioxides). It is shown that for ceramics with grains of the order of tens of microns the spectroscopic and population dynamics properties of the doping ions can be described consistently based on the crystal structure of the host material and assuming random distribution even at concentrations much larger than that available for the single crystals. It is inferred that from spectroscopic point of view these ceramics can substitute the crystals as laser materials and their enhanced compositional versatility enables tailoring of new laser materials. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermally stimulated polarisation and depolarisation currents in SLS glass exchanged with copper
Authors: Suszynska M. , Macalik B. , Krajczyk L. , Capelletti R. , Mora C.
Published: March 2007

Soda‐lime silicate glasses, with compositions corresponding to the immiscibility range, were studied to characterise their electrical properties and to determine the dependence of these characteristics on the glass microstructure. Dielectric measurements, analysed in terms of Maxwell/Wagner/Sillars theories of inhomogeneous dielectrics, have been used to investigate the phase separation characteristics of soda‐lime silicate glasses exchanged by copper. Such measurements are shown to provide evidences of the continuous or discontinuous nature of separated phases, the presence of which has been confirmed by the transmission electron microscopy observations. The results indicated that dielectric measurements are particularly useful in following phase‐separation‐processes in the oxide glasses. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Charge‐ordering in La0.333Ca0.667MnO3
Authors: Nikiforov A. E. , Gontchar L. E. , Popov S. E. , Kotomanov S. V. , Larin A. V.
Published: March 2007

Within the framework of strong electron‐lattice interaction of Mn3+ ions and orbital dependent exchange interaction model, the crystal and magnetic structures of charge ordered phase La1/3Ca2/3MnO3 are studied. The calculation results are in agreement with the “Wigner crystal” model. The estimated superexchange parameters confirm the qualitative conclusions of experimental works about frustrated magnetic structure with magnetic supercell (3a × b × 2c). The values of hyperfine magnetic fields on 55Mn nuclei in different charge states in charge ordering phase are calculated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The order‐disorder phase transformation in ion‐irradiated rare earth sesquioxide Dy2O3
Authors: Tang M. , Lu P. , Valdez J. A. , Stanek C. R. , Sickafus K. E.
Published: March 2007

In this report, we examine an irradiation‐induced order‐disorder phase transformation in polycrystalline pellets of the rare earth sesquioxide Dy2O3 using grazing incidence X‐ray diffraction (GIXRD) and transmission electron microscopy (TEM). This sesquioxide is characterized by a cubic C ‐type rare earth structure known as bixbyite. Samples were irradiated with heavy ion Kr++ (300 keV) at cryogenic temperature. GIXRD and cross‐sectional TEM observations reveal that the ordered body‐centered cubic bixbyite structure transforms to a disordered (anion deficient) fluorite structure in this irradiated sesquioxide. This observation is consistent with a radiation‐induced disordering process in which the oxygen superlattice associated with the bixbyite structure is destroyed and the material adopts an anion disordered fluorite structure as evidenced by the disappearance of characteristic GIXRD diffraction peaks resulting from ordering of the oxygen superlattice, and similar electron diffraction pattern features. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
XAFS and neutron diffraction study of the La1–xSrxCoO3
Authors: Efimov V. , Efimova E. , Karpinsky D. , Kochubey D. I. , Kriventsov V. , Kuzmin A. , Molodtsov S. , Sikolenko V. , Tiutiunnikov S. , Troyanchuk I. O. , Shmakov A. N. , Vyalikh D.
Published: March 2007

We have studied the effects of hole doping on the crystal and electronic structure of the La1–xSrxCoO3 (x = 0.0 ÷ 0.5) by neutron Rietveld analysis and its correlation with the X‐ray‐absorption spectroscopy data. The abrupt decrease of the Co–O distance and an increase of the Co–O–Co angle upon substitution of La3+ by Sr2+ in La1–xSrxCoO3 are attributed to a change in the band structure at the transition from semiconducting to metallic state. Upon strontium doping, a variation of Co L2,3‐edges in La1–xSrxCoO3 series suggests an increase of the mixed low Co4+ and high or intermediate Co3+ spin states. The possible explanation of the observed changes of the crystal and electronic structure in these cobaltites is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Time resolved luminescence of solids excited by femtosecond VUV pulses and synchrotron radiation
Authors: Kirm M. , Babin V. , Feldbach E. , Nagirnyi V. , Vielhauer S. , Guizard S. , Carré B. , De Grazia M. , Merdji H. , Belsky A. N. , Fedorov N. , Martin P.
Published: March 2007

Time‐resolved luminescence spectroscopy has been widely used in studies of electronic excitations and their dynamics in insulators. Present paper discusses the potential of vacuum ultraviolet spectroscopy applied for wide band gap crystals using classical synchrotron radiation as well as more recently developed pulsed femtosecond short‐wavelength light sources. Optical spectroscopy using novel free electron lasers and laser systems based on higher harmonic generation process allow detailed investigation of the interaction between electronic excitations and behaviour of solids under extreme radiation conditions. Significant changes in the quantum yield and emission decay kinetics as well as surface damage of single crystals were observed for CdWO4 and CaWO4 crystals studied in the temperature range of 8‐300 K. However, in the range of excitation densities applied, up to ∼1012 W/cm2, the nature of luminescence centres and their characteristic emission spectra remained similar to those observed at low excitation densities. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of deep traps on the optical properties of Tb3+ doped sol‐gel silica
Authors: Fasoli Mauro , Chiodini Norberto , Lauria Alessandro , Moretti Federico , Vedda Anna
Published: March 2007

In this study we investigate the role of traps on radio‐ and photo‐luminescence properties of terbium doped silica. The investigation is motivated by the promising characteristics of rare‐earth doped silica obtained by the sol‐gel technique as scintillating material. We focus on those phenomena that can be responsible for problematic properties such as the increase of radio‐luminescence sensitivity following repeated irradiations. A set of terbium doped silica with different terbium concentrations (0.03 mol%, 0.1 mol% and 10 mol%) prepared by the sol‐gel technique and densified at 1050 °C in oxidizing atmosphere has been considered. The effect of a post‐densification rapid thermal treatment on the RL and PL properties has also been investigated. This treatment improved the scintillation characteristics of the samples reducing their RL instability under prolonged irradiation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First‐principles modelling of defects in advanced nuclear fuels
Authors: Kotomin E. A. , Mastrikov Yu. A. , Zhukovskii Yu. F. , Van Uffelen P. , Rondinella V. V.
Published: March 2007

The cover picture of this issue of physica status solidi (c) has been taken from the article [1]. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum chemical investigation of donor–acceptor complexes of trimethylaluminum with Lewis bases of group 15 elements
Authors: Zagidullina Aygul E. , Vakulin Ivan V. , Vostrikova Olga S. , Talipov Rifkat F.
Published: March 2007

Lewis acid–base complexes AlMe3‐YH3 (Y = N, P, As) and their components have been investigated by means of quantum chemical techniques at the RHF, MP2, MP4, and DFT (PBE0) levels of theory, using the cc‐pVDZ and cc‐pVTZ basis sets. Theoretical complex formation energy for the AlMe3‐YH3 complexes increases in the order NH3 ≪ PH3 < AsH3 for all investigated complexes. Distortion of AlMe3 from planarity under complex formation leads to decreasing CAlC angles along with increasing AlC bond length. For all investigated adducts, an inverse negative relationship correlation between YAlC valence angle and AlY bond length has been found. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Meta‐analysis of putative human bornavirus sequences fails to provide evidence implicating Borna disease virus in mental illness
Authors: Dürrwald Ralf , Kolodziejek Jolanta , Herzog Sibylle , Nowotny Norbert
Published: March 2007

All Borna disease virus (BDV) sequences derived from human specimens published till date were thoroughly analysed and compared to sequences of BDV laboratory strains and to BDV sequences from animals which succumbed to classical Borna disease (BD). Despite high sequence conservation of the BDV genome, animal‐derived BDV sequences clustered according to their geographic origin. However, in marked contrast, human‐derived BDV sequences did not cluster according to their geographic origin but showed high sequence identities to BDV laboratory strains and animal‐derived BDVs handled in the laboratories reporting the human strains. Japanese, US, Australian and French human‐derived BDV sequences proved to be identical or very similar to animal‐derived BDV sequences from Germany, although the human specimens were collected hundreds to thousands of miles away from the central European BD endemic regions. These findings suggest that previous studies linking BDV to human neuropsychiatric disease may have been compromised by inadvertent sample contamination. Copyright © 2007 John Wiley & Sons, Ltd.
Early stopping designs based on progression‐free survival at an early time point in the initial cohort
Authors: Litwin Samuel , Wong Yu‐Ning , Hudes Gary
Published: March 2007

We introduce a new study design in which patients are evaluated early in their treatment for disease progression. Our design is appropriate when lack of progression, both early and late, is the criterion for treatment success. An initial cohort of n1 patients is followed until the last one has been evaluated. If enough of these patients are progression free (PF) at an early time point, t1 after arrival, a second cohort is recruited until n2 total patients are evaluable for PF survival at the final time t2. Otherwise, the trial is terminated for futility both early in time and with a minimal number of patients. Patients in the initial cohort who are PF at t1 continue on study and are again evaluated at t2. The design permits early stopping for rapid progression of disease, an indication of futility both for cytotoxic and newer non‐cytotoxic targeted therapies. The design tests the composite hypothesis of a probability p1 of being PF at t1 and p2 of being PF at t2 given PF at t1. Power and type I error are maintained at design point levels over a wide range of parameters p1 and p2. No distributional assumptions are needed other than the binomial, so the design provides rigorous power analysis for this type of study. Tables of optimal designs are supplied for a broad range of requirements. Copyright © 2007 John Wiley & Sons, Ltd.
An evolvable oestrogen receptor activity sensor: development of a modular system for integrating multiple genes into the yeast genome
Authors: Fox Jennifer E. , Bridgham Jamie T. , Bovee Toine F. H. , Thornton Joseph W.
Published: March 2007

To study a gene interaction network, we developed a gene‐targeting strategy that allows efficient and stable genomic integration of multiple genetic constructs at distinct target loci in the yeast genome. This gene‐targeting strategy uses a modular plasmid with a recyclable selectable marker and a multiple cloning site into which the gene of interest is cloned, flanked by two long regions of homology to the target genomic locus that are generated using adaptamer primers. We used this strategy to integrate into a single yeast strain components of the oestrogen receptor (ER) signalling network, comprising the human ERα and three reporter genes driven by oestrogen response elements (EREs). The engineered strain contains multiple reporters of ligand‐dependent receptor signalling, providing sensitive, reproducible, rapid, low‐cost quantitative assays of ERα activity in order to screen potential receptor agonists. Further, because two of the ERE‐driven reporter genes are required for growth in deficient media, the strain's growth rate—and therefore its fitness—depends on ligand‐induced ERα activity. This evolvable oestrogen receptor activity sensor (EERAS) can therefore provide the foundation of a long‐term experimental evolution strategy to elucidate ER structure–function relations and ligand‐receptor evolution. Copyright © 2007 John Wiley & Sons, Ltd.
Role in anaerobiosis of the isoenzymes for Saccharomyces cerevisiae fumarate reductase encoded by OSM1 and FRDS1
Authors: Camarasa Carole , Faucet Virginie , Dequin Sylvie
Published: March 2007

Saccharomyces cerevisiae possesses both a cytoplasmic and a mitochondrial fumarate reductase, encoded by FRDS1 and OSM1, respectively. While previous studies have shown that mutants lacking FRDS1 and OSM1 cannot grow under anaerobiosis (Arikawa et al., 1998), the physiological role of fumarate reductase (FR) remains poorly understood. Here, we report that an osm1 frds1 mutant is unable to grow anaerobically, even with glutamate as a sole nitrogen source, when succinate can be produced by the TCA oxidative branch. We also show that the growth of the mutant is not restored by adding acetoin, an alternative sink for NADH oxidation, but it is at least partly restored by the addition of oxygen or menadione, which can oxidize FADH2 in addition to NADH. These data indicate that the growth inhibition of the mutant is due to an inability to reoxidize FAD, rather than an indirect effect on NADH or an inability to produce succinate per se. During anaerobic growth, FRDS1 expression was two to eight times higher than that of OSM1, and fumarate reductase activity was higher in the osm1 mutant than in the frds1 mutant. FRDS1 expression was induced by anaerobiosis, and this induction was abolished in a rox1 mutant. We conclude that the formation of succinate is strictly required for the reoxidation of FADH2 during anaerobiosis, and that it is regulated through the control of FRDS1 expression when oxygen is limiting. Based on these data, we discuss the potential role of fumarate reductase in the regeneration of the FAD‐prosthetic group of essential flavoproteins. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis, Spectroscopy and Crystal Structures of Chiral Organic Ammonium Tetrathiometalates Showing N‐H···S and C‐H···S Interactions
Authors: Srinivasan Bikshandarkoil R. , Naik Ashish R. , Näther Christian , Bensch Wolfgang
Published: March 2007

The reaction of ammonium tetrathiometalate (NH4)2[MS4] (M = W or Mo) with the R(+) or S(−) forms of the organic amine α‐methylbenzylamine [PhCH(CH3)NH2] results in the formation of the corresponding non‐centrosymmetric bis(α‐methylbenzylammonium) tetrathiometalate complexes [PhCH(CH3)NH3]2[MS4] (R‐ammonium M = W 1; R‐ammonium M = Mo 2; S‐ammonium M = W 3, S‐ammonium M = Mo 4) which were characterized by elemental analysis, IR, Raman, UV‐Vis and CD spectra, X‐ray powder diffractometry and single crystal X‐ray crystallography. Compounds 1‐4 crystallize in the chiral space group P21 and constitute the first examples of structurally characterized chiral organic ammonium group VI tetrathiometalates. The structures of 1‐4 consist of two crystallographically independent chiral organic ammonium cations and a tetrahedral tetrathiometalate dianion. The N‐H···S and C‐H···S interactions between the anions and cations organise them such that the organic ammonium ions always point towards the S atoms of [MS4]2−.
Synthesis and Crystal Structure of [Pb(trz)(tfpb)(H2O)]: a Lead(II) Complex Containing 2,4,6‐Tris(2‐pyridyl)‐1,3,5‐triazine and 4,4,4‐Trifluoro‐1‐phenyl‐1,3‐butandionate
Authors: Marandi Farzin , Asghari Nasim , Gorbanloo Massomeh , Soudi Ali A. , Mayer Peter
Published: March 2007

[Pb(trz)(tfpb)(H2O)] (1) (trz and tfpb are the abbreviations of 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine and 4,4,4‐trifluoro‐1‐phenyl‐1,3‐butandionate, respectively) have been synthesized and characterized by elemental analysis and IR, 1H NMR, spectroscopy. The single‐crystal structure of 1 shows the coordination number of the Pb2+ ions is eight with three N‐donor atoms from a “trz” ligand and four O‐donors from the dionate ligand and one molecule of water. The supramolecular features in this complex are guided by lone pair activity and control of strong hydrogen bonds, weak directional intermolecular interactions and aromatic π‐π stacking interactions.
Labile Interactions in Aza‐aromatic Base Adducts of Lead(II) Thenoyltrifluoroacetonate
Authors: Marandi Farzin , Morsali Ali , Soudi Ali A.
Published: March 2007

The polymeric form of lead(II) thenoyltrifluoroacetonate, [Pb(ttfa)2], is modified by adduct formation with 2,2′‐bipyridine (bipy) and 1,10‐phenanthroline (phen) to give, in both cases, dimeric species [Pb2(bipy)2(ttfa)4] and [Pb2(phen)2(ttfa)4], respectively. Crystal structure determinations indicate that labile interactions involving the fluorine atoms and both the thenoyl and aza‐aromatic moieties may be important in determining the lattice arrays of these dimers, which are very similar, even though the dominant lattice forces may differ.
Metallation of Ligands with Biological Activity: Synthesis and X‐ray Characterization of the New Sulfathiazolato Complexes of Gold(I) and Silver(I): [(sulfathiazolato)AuPPh3] and [Ag(sulfathiazolato)]2 (sulfathiazole = N1‐2‐thiazolyl‐sulfanilamide)
Authors: de Oliveira Gelson Manzoni , Soccol Gris Lara Regina , de Lourenço Marques Lenice , Schulz Lang Ernesto
Published: March 2007

Sulfathiazole reacts with [Ph3PAu(CH3COO)] in benzene and with Ag(CH3COO) in methanol giving [(sulfathiazolato)AuPPh3] (1) and {[Ag(sulfathiazolato)]2}n (2). While the lattice of 1 contains single molecules with linear N–Au–P bonds, compound 2 performs a polymeric, one‐dimensional assembling of [Ag(sulfathiazolato)]2 dimers linked through intermolecular Ag···O=S=O interactions along the crystallographic axis b. The silver atoms achieve a tetrahedral configuration through Ag–Ag contacts which measure 2.8427(4) Å, considerably shorter than the normal bonding distance of metallic silver.
Transient Bloodletting of the Short Gastric Vein in the Reconstructed Gastric Tube Improves Gastric Microcirculation During Esophagectomy
Authors: Kono Koji , Sugai Hidemitsu , Omata Hideo , Fujii Hideki
Published: March 2007

Background

The reasons for anastomotic leakage in esophago‐gastrostomy have been proposed to be poor arterial inflow and insufficient venous drainage at the anastomotic site. In order to improve the congestive status, we developed a novel and easy surgical procedure of transient bloodletting from the short gastric vein after making a gastric tube during esophagectomy, and evaluated tissue blood flow.

Methods

Patients with esophageal cancer, who had received transthoracic esophagectomy and gastric tube reconstruction with intrathoracic anastomosis, were enrolled. After making a slender gastric tube, transient bloodletting from the short gastric vein at the most cardiac site was performed for 30 minutes. The tissue blood flow of the proximal end of the gastric tube was measured using a laser Doppler flowmeter, and was compared in the bloodletting group (n = 68) and the control group without bloodletting (n = 8).

Results

In the bloodletting group, tissue blood flow 5 minutes after the start of bloodletting was markedly increased in comparison to that before bloodletting (9.5 ± 4.9 ml/min/100 g vs. 24.1 ± 5.9 ml/min/100 g). The elevated levels of tissue blood flow remained at almost constant levels after ceasing bloodletting and lasted until esophago‐gastrostomy (20.1 ± 3.9 ml/min/100 g). On the contrary, in the control group without bloodletting, tissue blood flows were marginally increased following construction of a gastric tube, but the changes did not reach significant levels. When the tissue blood flow just before esophago‐gastrostomy was compared in the bloodletting and control groups, the flows in the bloodletting group were significantly more elevated than those in the control group (20.1 ± 3.9 vs. 15.2 ± 4.9 ml/min/100 g).

Conclusions

Transient bloodletting of the short gastric vein in the gastric tube during esophagectomy may improve the microcirculation of the oral side of the gastric tube.
Development of Small‐Diameter Vascular Grafts
Authors: Wang Xinwen , Lin Peter , Yao Qizhi , Chen Changyi
Published: March 2007

Introduction

Cardiovascular disease, including coronary artery and peripheral vascular pathologies, is the leading cause of mortality in the United States and Western countries. There is a pressing need to develop small‐diameter vascular vessels for bypass surgery and other vascular reconstructive procedures. Tissue engineering offers the prospect of being able to meet the demand for replacement of diseased vessels. Significant advances have been made in recent studies and provide confidence that success is attainable. For instance, a completely cellular approach culturing cells into tissue sheets and wrapping these layers was able to form a layered cellular vascular graft with impressive strength.

Methods/Results

In our experiments, decellularization and heparin immobilization grafts from porcine tissues implanted in a canine model could be repopulated from the host cells, indicating the grafts’ potential to develop into living tissues that can adapt and respond to changes in the body.

Conclusions

This review summarizes the current status of vascular grafts used clinically, updates the most recent developments on vascular tissue engineering, and discusses the challenges for the future.
Peripheral Arterial Occlusive Disease: Magnetic Resonance Imaging and the Role of Aggressive Medical Management
Authors: Lumsden Alan B. , Rice Terry W. , Chen Changyi , Zhou Wei , Lin Peter H. , Bray Paul , Morrisett Joel , Nambi Vijay , Ballantyne Christie
Published: March 2007

Atherosclerosis accounts for most peripheral arterial occlusive disease (PAD). Although many of the risk factors for atherosclerotic coronary artery disease (CAD) such as hyperlipidemia have been identified as risk factors for peripheral arterial disease, strong evidence is lacking that risk factor modification is effective in halting progression or improving outcomes. A better understanding is needed regarding the clinical and pathophysiologic responses to risk factor modification. This review describes current advances in the medical management for PAD including lipid modification antiplatelet therapy, angiotensin‐converting enzyme (ACE) inhibitors, beta‐blockers, exercise, and endovascular intervention. In addition, we discuss our active ELIMIT Trial (Effect of Lipid Modification on Peripheral Arterial Disease after Endovascular Intervention). We test the hypothesis that an aggressive regimen of serum lipid modification will inhibit the progression of atherosclerosis in femoral arteries and reduce the incidence of restenosis of femoral arteries following endovascular stenting by decreasing thrombosis and inflammation. This study will provide a novel strategy for retarding or preventing progression of atherosclerosis and re‐stenosis of peripheral arterial disease following arterial revascularization procedures. Importantly, our magnetic resonance imaging studies will provide quantitative data on the vascular lesions in PAD. These studies will advance our understanding of the molecular mechanisms of inflammation and thrombosis associated with aggressive lipid modification.
Special Variants of Differentiated Thyroid Cancer: Does It Alter the Extent of Surgery Versus Well‐Differentiated Thyroid Cancer?
Authors: Carling Tobias , Ocal Idris T. , Udelsman Robert
Published: March 2007

Introduction

Recently, more aggressive variants of so‐called well‐differentiated thyroid carcinomas have been identified such as the tall cell variant, columnar cell variant, diffuse sclerosing variant, insular carcinoma, and Hürthle cell (oncocytic, oxyphilic) carcinomas.

Methods

An evidence‐based review was performed to identify the optimal treatment recommendations for these thyroid cancers of intermediate differentiation.

Conclusions

Although some variation exists within the group, aggressive surgical and medical management are recommended for these neoplasias. Any such recommendations should, however, be viewed in the light of the fact that the current literature mainly consists of case reports, case series, and limited reviews. The clinical presentation, pathophysiology, diagnosis, and surgical and medical management for these thyroid cancers with intermediate differentiation are discussed.
Dynamic Features of the Rumen Metabolism of Linoleic Acid, Linolenic Acid and Linseed Oil Measured in Vitro
Authors: Jouany Jean‐Pierre , Lassalas Bernadette , Doreau Michel , Glasser Frédéric
Published: March 2007

The lipid quality of ruminant products is largely determined by the extent of rumen microbial biohydrogenation (BH) of polyunsaturated fatty acids (FAs) and the substances formed thereby. In vitro batch incubations with mixed rumen bacteria were tracked over 24 h to characterize the profiles and kinetics of the BH products from three lipid sources: pure linoleic acid (c9,c12–18:2), pure linolenic acid (c9,c12,c15–18:3) and linseed oil (mainly c9,c12,c15–18:3 in triacylglycerols). After 24 h of incubation biohydrogenation was more complete for c9,c12–18:2, which gave mainly stearic acid (18:0), than for c9,c12,c15–18:3, which yielded mainly trans‐18:1 FAs. This suggests inhibition of the final BH step (18:1 to 18:0). Incubations of c9,c12–18:2 resulted in high levels of carbon 10‐ and 12‐desaturated 18:1, t10,c12‐ and c9,t11‐CLAs. Incubations of c9,c12,c15–18:3 resulted in high levels of t11–18:1, carbon 13‐ and 15‐desaturated 18:1 as well as t11,c15–18:2 and 11,13‐CLAs. A comparative study of linolenic acid and linseed oil kinetics revealed that the BH process was not significantly slowed by the esterification of polyunsaturated FAs, but may have been limited by the isomerization step in which the cis12 double bond goes to the trans11 position. The disappearance rates of c9,c12–18:2 and c9,c12,c15–18:3 ranged from 23.6 to 44.6%/h. The wide variety of BH intermediates found here underlines the large number of possible BH pathways. These data help provide a basis for dynamic approaches to BH processes.
POVERTY AND CITIZENSHIP: AN OVERVIEW OF THE SOCIAL-POLICY ENVIRONMENT IN REPUBLICAN TURKEY
Authors: Bugra Ayse
Published: March 2007

The social–policy environment reflects the nature of state society relations and the content of citizenship in any given country. The present article situates analysis of the Turkish modernization experience in a historical overview of perspectives on poverty and social policy during the republican period. In surprising contrast to the emphasis placed on etatism as the defining feature of state society relations in Turkey, this overview shows that the responsibility for social assistance assigned to and assumed by the political authority has remained very limited throughout the period under study. Until the 1980s, when the country adopted an outward–looking, market–oriented development strategy, several mechanisms that were hardly compatible with the logic of either state redistribution or market exchange substituted for formal social–assistance measures. Today social–policy approaches are in a position to deal with pressures generated by market forces. The social–policy outlook of the current ruling party, which comes from an Islamic political tradition, at times appears to be more in conformity with basic trends observed through capitalist modernization in Europe than with those of both Kemalist authoritarianism and the multiparty period preceding the transition to an open–market economy.