bluuebunny/crossref_metadata_2025_split huggingface dataset:
Near-infrared Electroluminescence from Ytterbium(III) Complex
Authors: Kawamura Yuichiro , Wada Yuji , Iwamuro Mitsunori , Kitamura Takayuki , Yanagida Shozo 
Published: June 2003

Abstract
The room temperature near-infrared electroluminescence(EL) was observed from organic EL devices using the ytterbium(III) [Yb(III)] complex as an emitter over 15 V, though there was no spectral overlap between the lowest triplet state of ligand and the emissive level of Yb(III) ion needed for the intramolecular energy transfer. The EL emission with a peak at 985 nm was assigned to the 2F5/2 → 2F7/2 transition of Yb(III) ion.
A New Method for Preparing Nickel Oxide Supported Silica Pillared Phosphates with High Surface Area
Authors: Wang Wenhan , Tang Yi , Xiao Jinbing , Hua Weiming , He Nan , Gao Zi 
Published: June 2003

Abstract
A novel procedure was developed to prepare nickel oxide supported silica pillared zirconium phosphates whose surface areas and d-spacings are 125-198 m2/g and 2.1-2.3 nm respectively, whereas the samples prepared by conventional method only have surface areas less than 20 m2/g and d-spacings 1.8 nm. X-Ray diffraction (XRD), N2 adsorption and temperature programmed reduction (TPR) indicated that the materials obtained by the new method have better nickel oxide dispersion than those obtained by the conventional method.
Hydrothermal Soft Chemical Synthesis of Tunnel Manganese Oxides with Na+ as Template
Authors: Feng Qi , Horiuchi Tohru , Liu Lihui , Yanagisawa Kazumichi , Mitsushio Taikou 
Published: June 2003

Abstract
Na+ was used as template in the synthesis of tunnel manganese oxides from a layered manganese oxide under hydrothermal conditions. Two types of tunnel manganese oxides were obtained by the hydrothermal reaction. The manganese oxide with a one-dimensional (2 × 4) tunnel structure formed under low temperature conditions, and Na0.44MnO2 with a one-dimension complex tunnel structure under high temperature conditions. The mechanism of the transformation reaction can be explained from the structures of the products and template size.
Molecular Reorientation Induced by Sunshine Suggesting the Generation of Absolute Chirality
Authors: Ichimura Kunihiro , Han Mina 
Published: June 2003

Abstract
Both azimuthal and polar directions of azobenzene chromophores tethered to liquid-crystalline polymer backbones follow the orbital motion of the sun upon exposure of a film of the polymer to sunlight. The possibility to generate absolute chirality by the orbital motion of the sun is suggested.
Unusual [2+2] Photocycloaddition between Tryptamine and 3-Nitrocinnamic Acid in the Solid State
Authors: Ito Yoshikatsu , Fujita Haruo 
Published: June 2003

Abstract
A crystalline salt of tryptamine with trans-3-nitrocinnamic acid underwent cross photocycloaddition, leading to a cyclobutane adduct 1. Their solid mixture failed to give 1. This is the first [2+2] photocycloaddition of alkene to “N-unsubstituted” indoles.
Geochemical Signatures of Paleodepositional and Diagenetic Environments: A STEM/AEM Study of Authigenic Clay Minerals from an Arid Rift Basin, Olduvai Gorge, Tanzania
Authors: Hover Victoria C. , Ashley Gail M. 
Published: May 2003

AbstractOlduvai Gorge, Tanzania (East African Rift) exposes a 100 m thick Plio-Pleistocene sequence of dominantly volcaniclastic sediments deposited in a 50 km wide closed basin containing a playa lake. A scanning transmission electron and analytical electron microscopy (STEM/AEM) study of authigenic clay minerals in sediments from representative depositional environments in the basin (pyroclastic fan, fluvial plain, wetland, lake margin and lake basin) was undertaken to determine whether clay compositions and textures could provide unique geochemical fingerprints characteristic of source area (Plio-Pleistocene trachytic volcanicsvs.Precambrian quartzose-feldspathic basement) or paleoenvironmental conditions.Our study shows that compositional signatures obtained by clay minerals during early pedogenesis are inherited from their parent source rocks. Sediments sourced from volcanics contain highly disordered, dioctahedral smectite. Those sourced from Precambrian basement are similar, but are more Al-rich. Subsequent neoformation in the pedogenic (soil) or diagenetic (lake-margin, lake) environments results in the modification of original clay mineralogy, compositions, and textures, and unique paleoenvironmental fingerprints are acquired. Soils developed on the distal pyroclastic fan contain smectite with more Fe(III) and Mg than smectite from the proximal pyroclastic fan sediments. A trend of decreasing Al and increasing Mg content occurs in smectite compositions in samples from the fluvial to lake-margin and lake environments as a result of partial replacement of original dioctahedral Al-rich smectite by neoformed trioctahedral Mg-rich smectite (stevensite). Neoformed celadonite replaces smectite in the most saline lake sediments.The STEM/AEM data collectively indicate that diagenesis in the saline-alkaline lake results in the replacement of Al-rich dioctahedral smectite by Mg-rich trioctahedral smectite (stevensite) and Mg- and Al-rich celadonite. Thus, determination of clay mineral compositions at a basin-wide scale provides a useful tool for interpreting the spatial distribution of depositional and diagenetic environments.
The Crystal Structure of Roscoelite-1M
Authors: Brigatti Maria Franca , Caprilli Enrico , Marchesini Marco , Poppi Luciano 
Published: May 2003

AbstractSingle-crystal X-ray diffraction experiments were carried out on roscoelite crystals from Reppia, Val Graveglia, Italy. Roscoelite [structural formula: XII(Ba0.006K0.994)IV(Si3.150Al0.850) VI(Al0.040Fe0.150Mg0.100Mn0.062V1.696Ti0.003)O10(OH)2] shows a near-perfect three-dimensional stacking order with cell parameters a = 5.292(1), b = 9.131(2), c = 10.206(3) Å, β = 100.98(2)° and space group C2/m, which indicate a 1M polytype. The crystal structure was refined on the basis of Fo2 for 846 unique reflections to R1 = 3.29% calculated using 746 unique observed reflections [|Fo| ⩾ 4σ(Fo)]. The mean tetrahedral cation–oxygen atom distance, <T−O> = 1.641 Å, is close to the mean <T−O> value obtained for dioctahedral true micas from the literature, whereas the octahedral sheet is characterized by a larger cis-octahedral cation–oxygen atom bond distance <M2−O> = 2.020 Å which, together with the mean electron count, is consistent with V occupancy. The presence of V within the octahedral sheet produces the smallest tetrahedral rotation (α = 2.3°), the lowest flattening of the basal oxygen surface (Δz = 0.118 Å) and the narrowest interlayer separation (3.030 Å) in dioctahedral micas.
Structural Study of Maya Blue: Textural, Thermal and Solid-State Multinuclear Magnetic Resonance Characterization of the Palygorskite-Indigo and Sepiolite-Indigo Adducts
Authors: Hubbard Basil , Kuang Wenxing , Moser Arvin , Facey Glenn A. , Detellier Christian 
Published: May 2003

AbstractPalygorskite-indigo and sepiolite-indigo adducts (2 wt.% indigo) were prepared by crushing the two compounds together in a mortar and heating the resulting mixtures at 150 and 120°C, respectively, for 20 h. The samples were tested chemically to ensure that they displayed the characteristic properties of Maya Blue. Textural analysis revealed that no apparent changes in microporosity occurred in sepiolite or palygorskite after thermal treatment at 120°C (sepiolite) and 150°C (palygorskite) for 20 h. Micropore measurements showed a loss of microporosity in both sepiolite and palygorskite after reaction with indigo. The TGA-DTG curves of the sepiolite-indigo and palygorskite-indigo adducts were similar to their pure clay mineral counterparts except for an additional weight loss at ∼360°C due to indigo.The 29Si CP/MAS-NMR spectrum of the heated sepiolite-indigo adduct is very reminiscent of the spectrum of dehydrated sepiolite. Crushing indigo and sepiolite together initiates a complexation, clearly seen in the 13C CP/MAS-NMR spectrum, which can be driven to completion by heat application. In contrast to the broad peaks of the pure indigo 13C CP/MAS-NMR spectrum, the sepiolite-indigo adduct spectrum consists of a well-defined series of six narrow peaks in the 120.0–125.0 ppm range. In addition, the sepiolite-indigo spectrum has two narrow, shifted peaks corresponding to the carbonyl group and the C-7 (C-16) of indigo. A model is proposed in which indigo molecules are rigidly fixed to the clay mineral surface through hydrogen bonds with edge silanol groups, and these molecules act to block the nano-tunnel entrances.
Decolorization of Vegetable Oils: A Study of the Mechanism of Adsorption of β-Carotene by an Acid-Activated Bentonite from Cyprus
Authors: Christidis George E. , Kosiari Sotiria 
Published: May 2003

AbstractThe mechanism of decolorization of crude maize and sunflower oils was studied by means of adsorption of β-carotene by a low-grade bentonite, containing mixed-layered illite-smectite. Decolorization depends on temperature and the time required for equilibrium decreases with increasing temperature. The study of the kinetics of adsorption showed that decolorization of maize oil is a first-order process which occurs in two steps: a first fast step with higher activation energy (25.6 kJ mol−1), indicating the influence of a chemical interaction between the pigment and the clay surface, followed by a second slow step with low activation energy (12.3 kJ mol−1), characteristic of physical adsorption on the previously adsorbed molecules. Decolorization of sunflower oil is also a first-order process, described by a single mechanism with intermediate activation energy (19.0 kJ mol−1). Adsorption isotherms of decolorization of maize oil follow the Freundlich equation, indicating the existence of heterogeneous adsorption sites on the solid's surface. Heterogeneity is attributed both to different active centers on the smectite surface (Brönsted and Lewis centers) and to the different phases present in bentonite, such as illitic layers and clinoptilolite, which also have active centers on their surfaces.
Geordnete mesoskopische Strukturen durch Selbstorganisation und Transformation von Hybrid‐Nanostrukturen
Authors: Cölfen Helmut , Mann Stephen 
Published: May 2003

AbstractDie Organisation von Nanostrukturen über mehrere Längenskalen ist eine Schlüsselherausforderung im Design von integrierten Materialien mit verbesserten Funktionen. Derzeitige Ansätze greifen bevorzugt auf physikalische Methoden wie Musterbildung zurück, und nicht auf Methoden wie spontane chemische Selbstorganisation und Umwandlung von Baueinheiten über mehrere Längenskalen. Es sollte möglich sein, eine Chemie der organisierten Materie zu entwickeln, die auf Prozessen beruht, in denen die Zeit‐ und Längenskalenkopplung wechselwirkender Komponenten übergeordnete Architekturen mit eingebetteter Struktur hervorbringt. In diesem Aufsatz zeigen wir, wie das Wechselspiel von Aggregation und Kristallisation die Selbstorganisation auf der Mesoskala, kooperative Umwandlung und Reorganisation von organisch‐anorganischen Hybridbaueinheiten unter Bildung von Einkristallen mit Mosaikstruktur, Nanopartikelarrays und emergenten Nanostrukturen mit komplexer Form und Hierarchie auslösen kann. Wir schlagen vor, dass ähnliche Prozesse, die auf der Mesoskala wirksam sind, auch für Modelle der matrixvermittelten Keimbildung bei der Biomineralisation relevant sind.
From the first Gregory‐Coudé Telescope to Gregor
Authors: Wiehr E. 
Published: May 2003

AbstractThe historic development of the Göttingen Gregory‐Coudé Telescope is sketched. The use of a Gregory system for a solar telescope was driven by the severe disadvantages of an existing Cassegrain solar telescope. The possibility of placing a (water‐cooled) field‐stop at the prime‐focus diminishes heat stress as well as straylight on the mirrors behind the field‐stop. The measured aureole intensity of the first solar Gregory telescope, installed 1959 near Locarno, classifies that instrument as a ‘quasi coronograph’ and makes it particularly suitable for straylight‐sensitive observations. The coudé mounting with two folding flat mirrors (‘German type’) assures small and daily constant instrumental polarization. This was compensated in a first step with a co‐rotating tilted glass‐plate and a modified Bowen compensator fixed to the hour axis. In a later step, a halfwave plate between both folding flat mirrors simulates the polarimetric situation of zero‐declination. The Gregory‐Coudé Telescope was then particularly suitable for polarimetry; it operated 25 years near Locarno and finally 15 years on Tenerife.
POLIS: A spectropolarimeter for the VTT and for GREGOR
Authors: Schmidt W. , Beck C. , Kentischer T. , Elmore D. , Lites B. 
Published: May 2003

AbstractThe polarimetric Littrow Spectrograph POLIS is designed for vector polarimetry at high angular and spectral resolution. It measures the magnetic field simultaneously in the photosphere and the chromosphere of the sun. Both branches of the polarimetry unit are dual beam systems with a single rotating modulator for both wavelengths and polarizing beam splitters in front of each CCD camera. POLIS has been installed at the VTT on Tenerife and has seen First Light on 17 May 2002. A modified version of POLIS will be developed for the balloon mission Sunrise. That version will have UV capabilities down to 200 nm.
A CCD‐based guiding and control system for solar telescopes
Authors: Klvaňa M. , Bumba V. , Sobotka M. 
Published: May 2003

AbstractWe describe a system for guiding and control of motion of solar telescopes based on a determination of the position of the full solar disk on a CCD chip. The system computes the position of the disk center and, according to the difference between the instantaneous and required positions, it controls the motion of the telescope to compensate the deviation. The instantaneous position of the disk center is the basic input for the telescope's guiding and coordinate system. Brightness inhomogeneities of the solar limb caused by clouds are checked in real time. The function of the system can be suspended automatically if the clouds degrade the accuracy of guiding. The system also makes possible to check the correct focus and to evaluate the image quality.
High sensitivity polarimetry
Authors: Gandorfer A.M. 
Published: May 2003

AbstractOver the last decade spectro‐polarimetry evolved to ever higher sensitivity levels. New techniques and instruments allow us to address weak polarization signals, which are caused by scattering in the solar atmosphere. In this paper a review on the development of spectro‐polarimetric investigations of scattering physics and its coupling to the solar magnetic field will be given. Starting from a technical point of view it will be demonstrated how our understanding of scattering phenomena and their role in solar physics in general has reached its current state. An outlook on future spectro‐polarimetry with new large solar telescopes concludes this review.
Solar observations from space and from the ground
Authors: Curdt W. 
Published: May 2003

AbstractRecent results from space missions like YOHKOH, SOHO or TRACE as well as ground‐based observations clearly indicate that physical processes of most solar phenomena take place on small scales, which are still below the resolution of the instruments employed. There is an urgent need for observations at higher resolution and also for their extension to multi‐wavelength regimes. Space‐borne as well as ground‐based instruments have limitations of the present‐day technology, although in a different way. In this communication, an overview of space instruments currently in operation or in the preparation phase is presented and references to more detailed information are given.
Spectroscopy of solar prominences from space and ground
Authors: Dammasch I.E. , Stellmacher G. , Wiehr E. 
Published: May 2003

AbstractTwo quiescent solar prominences were observed in July 2000 from SUMER aboard SOHO and from the two German solar telescopes at Tenerife. Two‐dimensional images taken at the VTT simultaneously in the spectral lines Hβ at 4862 Å and Ca II at 8542 Å show no significant spatial variation of their pressure‐sensitive emission ratio. Slit spectra of the Ca II 8542 Å and He I 10830 Å lines obtained at the Gregory‐Coudé telescope yield 8000 K < Tkin < 9000 K and 3 km/s < Vn–th < 8 km/s. Among the various spectral ranges observed with SUMER, we first investigate the Lyman emission lines, which were fitted by Gaussians yielding reliable spectral radiances and line widths for the series members 5 < k < 18. A determination of the level population gives for the lower series members a Boltzmann temperature of 60 000 K, the higher members being over‐populated. This temperature indicates an origin of the Lyman lines from hot surroundings of the cool prominence body seen in the ground‐based data; this also holds for the ‘hotter’ SUMER lines.
Does the ion cyclotron exist in the inner corona?
Authors: Raouafi N.‐E. 
Published: May 2003

AbstractThe present work is about the interpretation of the linear polarization of the O VI D2 (λ1032) coronal line observed by SUMER/SoHO. We take into account the effect of the Doppler redistribution due to the scattering ions motion. We consider the cases of isotropic and anisotropic velocity field distributions. The latter can be interpreted by the ioncyclotron effect that affects heavy ions in the solar corona. The comparison of the numerical results with the observations yields constraints on the solar wind outflow speed and on the velocity field distribution of the O5+ ions at low coronal altitudes in the polar holes.
Models of a mean granular cell
Authors: Puschmann K. , Ruiz Cobo B. , Vázquez M. , Bonet J.A. , Hanslmeier A. 
Published: May 2003

AbstractFrom inversion of a time series of slit spectra, observed in a quiet region of the solar photosphere, averaged models of a granular cell have been obtained showing the stratification of physical quantities versus optical depth and geometrical height. Furthermore a semi‐empiric dynamic model of a mean granular cell has been derived and the results are presented.
Magnetic and velocity fields of active regions
Authors: Choudhary D.P. , Gosain S. 
Published: May 2003

AbstractWe have observed about 15 active regions on the Sun, with the Advanced Stokes Polarimeter and Dick Dunn Telescope at NSO/SP to map the Stokes parameters in the photospheric Fe 6302.5 Å and chromospheric Mg I 5173 Å lines, during 1999‐2002. The observations are corrected for dark current, gain, instrumental polarization and cross‐talk using ASP pipeline. The wavelength calibration is carried out using the O2 telluric line 6302 Å which is also present in the observations. The photospheric and chromospheric longitudinal magnetograms are made from the Stokes V profiles, which were intercalibrated with the Kitt Peak magnetograms. The plasma motions are inferred from the line bisector measurements at different positions of the spectral line. In this paper we present the height dependence of Doppler velocity scatter plots of a sunspot in the photospheric Fe I 6302 Å line.
Study of bright points in the off‐band Hα filtergrams of active regions
Authors: Choudhary D.P. , Gosain S. 
Published: May 2003

AbstractHα filtergrams of selected active regions are obtained by the six inch refractor telescope at Udaipur Solar Observatory through a birefringent filter of 0.5 Å full width at half maximum. The field of view is ∼4 × 5 arcmin with a spatial resolution of better than one arc sec. The filtergrams are obtained in the wavelength range of ‐1 to +1 Å centered at 6563 Å at steps of 0.1 ° A. A complete scan takes about 5 seconds (occasionally longer). The images are recorded with a cooled CCD camera and corrected for dark current and flat field. We observe the bright points in the filtergrams beyond 0.5 Å off line center. In general, these features are located away from the strong field regions. We study their property with respect to the co‐temporal photospheric magnetograms obtained with the GONG instrument at Udaipur. This might help in understanding their relation with the magnetic flux emergence and annihilation.
Infrared photometry of a sunspot near the disk center
Authors: Stangl S. , Sobotka M. , Bonet J. A. , Vázquez M. , Hanslmeier A. 
Published: May 2003

AbstractA time series of broadband images of a sunspot near the disk center was obtained simultaneously in two wavelength bands at 0.56 μm and 1.55 μm at the German VTT on June 17, 1998. We computed intensity difference images of the best frame pairs which reveal information about the facular distribution in the present field of view. Faculae are found around pores, in the quiet granulation and as well around the sunspot penumbra.
Interpretation of observations by inversion
Authors: del Toro Iniesta J.C. 
Published: May 2003

AbstractThe most recent developments in inversion techniques of the radiative transfer equation are critically reviewed and some of their findings are summarized to illustrating their achievements. Two significantly different approaches are currently being used that deserve consideration, each characterized by whether or not the model solar atmospheres are changed iteratively by the algorithm. The comparison between the two may help in finding future inversion techniques that can solve many challenging problems of solar physics that still need to be properly settled. These problems themselves suggest strategies that look more suitable than others.
High‐frequency waves and granulation
Authors: Zhugzhda Y.D. 
Published: May 2003

AbstractThe theory of periodical shear flow is applied for the exploration of the effect of solar granulation on highfrequency waves in the solar photosphere. It is shown that upgoing and downgoing waves are trapped in intergranular spaces and granules, respectively. Upgoing waves in fast downflows are unstable. The theory is in a good agreement with observations.
3‐D hydrodynamic simulations of the solar chromosphere
Authors: Wedemeyer S. , Freytag B. , Steffen M. , Ludwig H.‐G. , Holweger H. 
Published: May 2003

AbstractWe present first results of three‐dimensional numerical simulations of the non‐magnetic solar chromosphere, computed with the radiation hydrodynamics code CO5BOLD. Acoustic waves which are excited at the top of the convection zone propagate upwards into the chromosphere where the waves steepen into shocks. The interaction of the waves leads to the formation of complex structures which evolve on short time scales. Consequently, the model chromosphere is highly dynamical, inhomogeneous, and thermally bifurcated.
European businesses, national priorities: pioneers and laggards of ecological modernization
Authors: Drake Frances , Purvis Martin , Hunt Jane , Millard Debbie 
Published: May 2003

AbstractEcological modernization has been widely adopted by western politicians as a means to achieving a balance between continued economic growth and sustainable development. Countries with consensual forms of government, such as Germany, seem to be leading the field in developing such policies. Thus, it might be expected that it will be the industries within these states that reap the win–win benefits of greater attention to the environment. This paper explores the reality of these expectations through semi‐structured interviews with business managers in three EU countries: France, Germany and the United Kingdom. Contrary to expectations the attitudes of German managers to the environment did not differ significantly from their French and British counterparts. Differences in behaviour were perceived as a product of stricter environmental regulation in Germany rather than any deep‐seated changes in outlook. Ecological modernization was not seen as an answer to Germany's current economic predicament. Copyright © 2003 John Wiley & Sons, Ltd. and ERP Environment