bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigations of the emission properties of single CdS‐nanocrystallites
Authors: Tittel Jakob , Göhde Wolfgang , Koberling Felix , Mews Alf , Kornowski Andreas , Weller Horst , Eychmüller Alexander , Basché Thomas 
Published: July 2012

AbstractSemiconductor nanocrystallites (NCs) with a radius in the range of the bulk excition radius exhibit a strong quantum size effect. We investigated CdS‐NCs, that were spin coated on a glass cover slip, with a low temperature confocal microscope, At low coverage we could image the fluorescence light from single NCs. The typical emission spectra of single NCs show four peaks. Besides the main peak related to near bandgap recombination, up to two Lo‐phonon satellites and one blue shifted peak were observed. It could be shown that the absorption can be polarization dependent. From the images as well as from the intensity autocorrelation function it could be concluded that the fluorescence emission of single NCs is interrupted by dark periods. In addition, spectral shifts in the dispersed fluorescence emission could be observed.
Synthesis and characterization of catalysts based on ligand‐stabilized clusters incorporated in mesoporous oxides
Authors: Junges U. , Schüth F. , Schmid G. , Uchida Y. , Schlögl R. 
Published: July 2012

AbstractMCM 41 was loaded with ligand‐stabilized palladium clusters in the size range of 3‐4 nm via different pathways. A mixture of seven‐ and eight‐shell clusters (Pd7/8(phen)) was directly introduced into the mesoporous structure during the synthesis of MCM 41 as well by incipient wetness impregnation. The Samples were characterized by X‐ray diffraction, N2‐sorption, DTA and TEM. The clusters show different thermal stability depending on the synthesis pathway used. In situ incorporation leads to a decomposition of the Pd clusters after calcination at 873 K. However, the clusters that were introduced by incipient wetness impregnation are thermally stable up to 513 K in air. As a first catalytic test the oxidation of CO with synthetic air was used. Compared to catalysts prepared by conventional methods with appropriate palladium salts, the impregnated samples show high activity in the CO oxidation.
Synthesis and characterization of PbS quantum dots embedded in the polyaniline film
Authors: Gaponik N. P. , Sviridov D. V. 
Published: July 2012

AbstractThe Polyaniline films loaded with quantum‐confined PbS particles were prepared by the incorporation of Pb2+ ions into the polyaniline matrix during electropolymerization followed by their conversion into sulphide form. The Rutherford backscattering measurements indicate that the precipitation of PbS nanophase occurs mainly near the outer face of the film. The shape of the photocurrent spectrum of Q‐PbS‐doped polyaniline film was shown to be dependent on the regime of electropolymerization of the polyaniline host. The anodic polarization produces the blue shift of the excitonic maximum in the photocurrent spectrum that can be attributed to the positive charging of Q‐PbS particles embedded in the polyaniline matrix.
Raman spectroscopy on CdZnSe/ZnSe quantum wires
Authors: Lermann G. , Bischof T. , Schreder B. , Materny A. , Kiefer W. , Kümmell T. , Bacher G. , Forchel A. , Landwehr G. 
Published: July 2012

AbstractCdZnSe/ZnSe quantum wires with lateral widths down to 20 nm were produced by means of electron beam lithography and wet chemical etching. In order to study the wire width dependence of the vibronic properties, micro resonance Raman spectroscopy has been performed. By this method Raman spectra could be obtained as a function of the wire width. The Raman spectra taken from the Cd0.1Zn0.9Se wires showed only one peak in the wavenumber region of the ZnSe LO phonon. Due to the small Cd content the ZnSe LO phonon of the barrier layer and the ZnSe‐like LO phonon of the Cd0.1Zn0.9Se layer are not separated from each other. Nevertheless, a wire width dependence of the LO phonon wavenumber position is observed. This behavior is due to strain relaxation in the biaxially strained Cd0.1Zn0.9Se layer.
Mesoporous inorganic monoliths from lyotropic liquid crystalline polymer templates
Authors: Weißenberger Markus C. , Göltner Christine G. , Antonietti Markus 
Published: July 2012

AbstractLyotropic phases of amphiphilic block copolymers and water are used as templates for the synthesis of monolithic mesoporous silica objects. These monoliths show a large specific surface area, high porosity, and a narrow pore size distribution. The template can be removed from the monolithic material by solvent extraction. The polymerization of an organic monomer is conducted in the bicontinuous pore system of the silica monolith. Removal of the inorganic matter affords a nanostructured organic polymer, such proving both bicontinuity as well as complete accessibility of the pore system. It is suggested that bicontinuous monolith materials with pore sizes in the nanometer range are useful media for studying the effects of confinement on matter.
Formation of ceramic oxide nanoparticles in low pressure flames: Experiment and computersimulation
Authors: Lindackers D. , Roth P. 
Published: July 2012

AbstractLow pressure premixed H2/O2/Ar flames were stabilised on a flat, water‐cooled sintered bronze plate at pressures 27.5 mbar ≤ p ≤ 30 mbar and doped with small amounts (100‐400 ppm) of Al(CH3)3 or SiH4 acting as Al‐ and Si‐precursors, respectively. In the combustion process, the condensable oxidation products Al2O3 and SiO2 were formed and undergo phase transition by homogeneous nucleation. Coagulation of nuclei and particles driven by Brownian motion contribute to the further evolution of the particle size distribution. Samples of the combustion aerosol were extracted at different heights from the flame by a molecular beam sampling device and were in situ analysed due to particle mass and chemical species composition. Charged particles of both polarities were found at flame co‐ordinate × ≥ 20 mm. In the case of SiO2 particles, their mean diameter was 4.2 nm ≤ dp ≤ 7.6 nm. Al2O3 particles were determined to be in the size range 3.8 nm ≤ dp ≤ 4.7 nm. Due to the rapid precursor conversion and the strong particle formation rate, gaseous intermediates of the oxidation products were not found in the flame. In the Al(CH3)3 doped flame, the formation of the reaction by‐product CO2 was monitored. The experimental results on SiO2 particle formation were verified by a theoretical model. It includes the oxidation of H2 and SiH4 in burner stabilised flames, the homogeneous nucleation of SiO2‐vapour, Brownian coagulation, and particle charging by ion diffusion. Good agreement in particle size and size distribution between the experimental results and the computer simulations was obtained.
Growth kinetics of nanocrystalline CuTi by means of time‐resolved SAXS
Authors: Wagner J. , Janßen S. , Hirscher M. , Boesecke P. , Hempelmann R. 
Published: July 2012

AbstractNanocrystalline Cu0.50Ti0.50 was prepared by controlled recrystallisation of amorphous CuTi. Since the crystalline particles have a density slightly higher than the amorphous matrix, a difference in electron density and, as consequence, in scattering length density results.This enabled us to study the crystallisation process of metallic glasses by means of small angle X‐ray scattering (SAXS) in real‐time, using the high intensities available at the synchrotron radiation source ESRF.
Preparation of nanocrystalline Ag‐ME (ME = Co, Fe and Ni) materials by gas flow condensation technique
Authors: Dimesso L. , Humm S. , Fuess H. , Hahn H. 
Published: July 2012

AbstractHeterogeneous Ag‐ME (ME = Fe, Co, Ni) nanostructured alloys have been prepared by a new process utilizing co‐evaporation of the metals in a continuous gas flow. Inert gas, at different final pressures, has been injected into a ultra‐high vacuum chamber through a nozzle in order to establish a convectional flow that carried nano‐crystallites of the ME over an evaporation source of Ag, so that part of the atoms of silver condensed at the surface of the ME crystallites as thin coating. The average grain size of the Ag‐ME powders, determined both by X‐ray diffraction and surface area analysis, increased with the He pressure (pHe). Electrical measurements revealed a decrease of the resistivity of the compacted Ag‐ME samples in a magnetic field; values of the giant magnetoresistance effect as large as 26% (ME = Co, pHe = 100 Pa), 8% (ME = Fe, pHe = 1000 Pa) and 7% (ME = Ni, pHe = 800 Pa) have been observed, at room temperature and a magnetic field H = 1.5 T.
Electronic spectroscopy of aromatic molecules in jet‐cooled hydrogen bonded clusters ‐ structure and fluxionality
Authors: Kleinermanns K. , Gerhards M. , Schmitt M. 
Published: July 2012

AbstractSpectroscopical and theoretical investigations of various aspects of molecular solvation by hydrogen bonding are presented. The focus is on clusters of phenol with water to study the hydrogen bond in water networks and the solvent interaction with the phenol OH group and the aromatic ring. The phenol dimer and trimer are considered to elucidate the effect of electronic excitation in different cluster moieties. Excited state proton transfer reactions are discussed using clusters of phenol with ammonia as an example.
A semiempirical study of the fluorescence properties of large charge transfer compounds: N,N‐dimethylanilino‐bis‐pyrazolopyridine
Authors: Parusel Andreas B. J. , Schamschule Rudolf , Köhler Gottfried , Parusel Andreas B. J. 
Published: July 2012

Abstract4‐(4′‐N,N‐dimethylaminophenyl)‐3,5‐dimethyl‐1,7‐diphenyl‐bis‐pyrazolo‐[3,4‐b;4′,3′e]‐pyridine (DMA‐DMPP), was recently synthesized as an example of a bulky electron donor‐acceptor compound and was examined by spectroscopic methods. The molecule consists of several subunits of different redox properties and the observed behavior was thus interpreted by an intramolecular charge transfer model. This hypothesis is validated by semiempirical excited state calculations. They are focused on the coupling of intramolecular charge transfer to various relaxation modes, e.g. rotation about single bonds leading to decoupling π systems. Rotation about the single bond connecting the dimethylanilino and heteroaromatic subunit results as the most important relaxation coordinate. The two moieties non orthogonal in the ground state become perpendicularly oriented in the optimum excited state. In this conformation the dipole moment also becomes maximal. These results agree satisfactorily with the observation of a marked red shift of its fluorescence in polar solvents and dual fluorescence found in polar, protic environment.
In situ UV‐Vis spectroelectrochemical evidence of an EC mechanism in the electrooxidation of N‐Methylaniline
Authors: Malinauskas Albertas , Holze Rudolf 
Published: July 2012

AbstractThe anodic oxidation of N‐methylaniline (NMA) on optically transparent electrodes was studied with in situ UV‐Vis spectroscopy. An absorbance band at Δmax=443 nm was ascribed to the formation of an intermediate species formed during electrolysis. The intermediate was found to react with solution NMA, forming a soluble polymer, which shows an absorbance band at Δmax=750 nm. Thus, an EC mechanism of NMA electrooxidation was confirmed. It was concluded, that the presence of an alkyl chain at the aniline nitrogen stabilizes the intermediate and enables its detection by simple spectroelectrochemical technique on a minute time scale. Anodic oxidation of NMA on ITO electrode, covered with a thin layer of polyaniline, was found to proceed faster than on a bare electrode. A copolymerisation of NMA and aniline was showed to proceed.
Modeling of nickel surface state in electrocatalytic hypophosphite oxidation according to on‐line electrochemical mass spectrometry studies
Authors: Jusys Zenonas , Vaškelis Algirdas 
Published: July 2012

AbstractComputer simulation of possible distributions of Had and Dad atoms developed on nickel surface as a result of partial reactions of anodic hypophosphite oxidation and cathodic proton (deuteron) discharge from water respectively was used for modeling of the catalyst surface state according to on‐line electrochemical mass spectrometry data. The simpliest lattice‐gas model gives a probable qualitative description of the catalyst surface state and allows the genesis of electrocatalytic properties of nickel with the electrode potential to be followed. Location of anodic and cathodic half‐reactions at special types of sites was evidenced, leading to formation of non‐equilibrium H2, HD and D2 mixtures with the lower HD content than that predicted theoretically.
Validation of the frequency shift of thickness‐shear‐mode resonators in liquids ‐ determination of the activation energy of viscosity
Authors: Bund A. , Schwitzgebel G. 
Published: July 2012

AbstractThe frequency shift of thickness‐shear‐mode resonators (f0 = 10 MHz) in liquids was described as combined effects of rigid mass loading and viscous damping. The thus obtained relationship was used to determine the activation energy of viscosity by impedance measurements on TSM devices in liquids at temperatures between 20 and 45°C. Good agreement with literature data for water, methanol, ethanol, 1‐propanol, and 1‐butanol was achieved.
Multiscale Simulation of the Fluidized Bed Granulation Process
Authors: Dosta M. , Antonyuk S. , Heinrich S. 
Published: July 2012

AbstractA novel multiscale modeling approach was developed, implemented as basis of a simulation environment and applied to the fluidized bed spray granulation process. The high detailing level of the simulation is based on the process description on different time and length scales which are coupled by interscale communication laws. This allows considering a higher amount of process parameters, compared to the semi‐empirical models which are typically used. The developed concept represents the production plant as flow sheet, with its further dynamic simulation on the macroscale. The influence of parameters such as viscosity of the sprayed suspension, nozzle positions, and temperature of the fluidization air on the whole process can be considered on the microscale.
Soft X‐ray Imaging and Spectromicroscopy: New Insights in Chemical State and Morphology of the Key Components in Operating Fuel‐Cells
Authors: Bozzini Benedetto , Abyaneh Majid Kazemian , Amati Matteo , Gianoncelli Alessandra , Gregoratti Luca , Kaulich Burkhard , Kiskinova Maya 
Published: July 2012

AbstractFuel cells are one of the most appealing environmentally friendly devices for the effective conversion of chemical energy into electricity and heat, but still there are key barriers to their broad commercialization. In addition to efficiency, a major challenge of fuel‐cell technology is the durability of the key components (interconnects, electrodes, and electrolytes) that can be subject to corrosion or undesired morphology and chemical changes occurring under operating conditions. The complementary capabilities of synchrotron‐based soft X‐ray microscopes in terms of imaging, spectroscopy, spatial and time resolution, and variable probing depths are opening unique opportunities to shed light on the multiple processes occurring in these complex systems at microscopic length scales. This type of information is prerequisite for understanding and controlling the performance and durability of such devices. This paper reviews the most recent efforts in the implementation of these methods for exploring the evolving structure and chemical composition of some key fuel cell components. Recent achievements are illustrated by selected results obtained with simplified versions of proton‐exchange fuel‐cells (PEFC) and solid‐oxide fuel‐cells (SOFC), which allow in situ monitoring of the redox reactions resulting in: 1) undesired deposits at interconnects and electrodes (PEFC); 2) material interactions at the electrode–electrolyte interface (PEFC); 3) release of corrosion products to the electrolyte phase (PEFC, and 4) mass‐transport processes and structural changes occurring at the high operation temperatures of SOFC and promoted by the polarization.
ChemInform Abstract: Interaction of Vanadium with Iron and Antimony at 870 and 1070 K.
Authors: Romaka Vitaliy V. , Romaka Lyubov , Stadnyk Yuriy , Gvozdetskii Volodymyr , Gladyshevskii Roman , Skryabina Nathaliya , Melnychenko Nathaliya , Hlukhyy Viktor , Faessler Thomas 
Published: July 2012

AbstractThe isothermal sections of the V—Fe—Sb ternary system at 870 and 1070 K are constructed.
ChemInform Abstract: Electrochemical Behavior of α1/α2‐ [Fe(H2O)P2W17O61]7‐ Isomers in Solution: Experimental and DFT Studies.
Authors: Vila Neus , Aparicio Pablo A. , Secheresse Francis , Poblet Josep M. , Lopez Xavier , Mbomekalle Israel M. 
Published: July 2012

AbstractThe influence of protonation on the redox behavior of the two title isomers is characterized by cyclic voltammetry in aqueous media at pH values from 0.5 up to 8.0 and by DFT calculations.
ChemInform Abstract: Oxidation State of Uranium in A6Cu12U2S15 (A: K, Rb, Cs) Compounds.
Authors: Kanatzidis Mercouri G. , et al. et al. 
Published: July 2012

AbstractBlack single crystals of the title compounds are synthesized from mixtures of U, Cu, and S using Rb2S3 or M2S (M: K, Cs) as reactive flux (793—823 K, 7—8 d, 40 and 70 wt.% yield for the Rb and K compound, respectively).
ChemInform Abstract: Synthesis of Molecular Dodecanuclear Carbon‐Centered Rhenium Cluster Re12CS17 and Its Conducting Properties.
Authors: Fedorov Vladimir Efimovich , Gabuda Svyatoslav Petrovich , Kozlova Sevtlana Gennad'evna , Gayfulin Yakov Maksumovich , Mironov Yuri Vladimirovich , Rizhikov Yakov Raisovich , Uvarov Nikolay Favstovich 
Published: July 2012

AbstractYields of compounds (II) and the anhydrous compound (III) are given in gram.
ChemInform Abstract: Crystal Structure of YbCu6In6 and Mixed Valence Behavior of Yb in YbCu6‐xIn6+x (x = 0, 1, and 2) Solid Solution.
Authors: Subbarao Udumula , Peter Sebastian C. 
Published: July 2012

AbstractHigh quality single crystals of YbCu6In6 are prepared from the elements using excess In as a flux (alumina crucible, 1000 °C for 10 h, 850 °C for 96 h).
ChemInform Abstract: Iron(II)‐Catalyzed Enantioselective meso‐Epoxide‐Opening with Anilines.
Authors: Plancq Baptiste , Ollevier Thierry 
Published: July 2012

AbstractA highly enantioselective method for the catalytic opening of aromatic meso‐epoxides (I) and (IV) with aniline derivatives (II) is developed.
ChemInform Abstract: InBr3‐ and AgOTf‐Catalyzed Beckmann Rearrangement of (E)‐Benzoheterocyclic Oximes.
Authors: Tandon Vishnu K. , Awasthi Anoop K. , Maurya Hardesh K. , Mishra Pushyamitra 
Published: July 2012

AbstractBeckmann rearrangement of oximes (I) and (III) using a catalyst formed from InBr3 and AgO‐Tf provides access towards the potentially bioactive rearranged products (II) and (IV), exclusively.
ChemInform Abstract: 8‐Bromocaffeine (8‐BC): A New Versatile Reagent for Conversion of Aldoximes into Nitriles.
Authors: Rad Mohammad Navid Soltani , Behrouz Somayeh , Nekoei Abdo‐Reza 
Published: July 2012

AbstractMicrowave chemistry allows a rapid conversion of a broad spectrum of aldoximes including aliphatic, aromatic and heterocyclic systems.
ChemInform Abstract: Ester as a Blocking Group for Palladium‐Catalyzed Direct Forced Arylation at the Unfavorable Site of Heteroaromatics: Simple Access to the Less Accessible Regioisomers.
Authors: Chen Lu , Bruneau Christian , Dixneuf Pierre H. , Doucet Henri 
Published: July 2012

AbstractOptimal reaction conditions are found for the palladium‐catalyzed direct arylation of substituted thiophenes (I), furan (VI), pyrroles (VIII), and pyrazole (X).
ChemInform Abstract: Carboxylation of Terminal Alkynes with Carbon Dioxide Catalyzed by Poly(N‐heterocylic carbene)‐Supported Silver Nanoparticles.
Authors: Yu Dingyi , Tan Mei Xuan , Zhang Yugen 
Published: July 2012

AbstractThe catalyst can be easily recycled and used in at least five runs with only a slight loss in activity.
ChemInform Abstract: TMSCl as a Rate‐Accelerating Additive in Acylations of Amines with 5‐(α‐Amino‐α′‐hydroxy)methylene Meldrum Acids.
Authors: Janikowska Karolina , Makowiec Slawomir 
Published: July 2012

AbstractA wide range of nonsymmetrical malononic acid diamides, esters, and thioesters of malonamic acid is prepared.
ChemInform Abstract: Modified Shapiro Reactions with Bismesitylmagnesium as an Efficient Base Reagent.
Authors: Kerr William J. , Morrison Angus J. , Pazicky Mrek , Weber Tina 
Published: July 2012

AbstractCompared to the common lithium systems, the magnesium base requires only a slight excess (1‐2 equiv.) of the Weinreb reagent to produce functionalized styrenes.
ChemInform Abstract: Synthesis of Polyfunctionalized Acrylates via One‐Pot Reactions of Arylamines, Methyl Propiolate, Aromatic Aldehydes, and Active Methylene Compounds.
Authors: Sun Yan , Sun Jing , Yan Chao‐Guo 
Published: July 2012

AbstractThe four‐component reaction is successfully extended to pivaloylacetonitriles, 1,3‐cyclopentadienone, and 4‐hydroxycoumarin as active methylene compounds.
ChemInform Abstract: Eco‐Friendly Synthesis of α‐Aminonitriles from Ketones in PEG‐400 Medium Using Potassium Hexacyanoferrate(II) as Cyanide Source.
Authors: Hu Xiaochun , Ma Yuanhong , Li Zheng 
Published: July 2012

AbstractBenzoyl cyanide, generated in a prestep from K4[Fe(CN)6] and benzoyl chloride, is demonstrated to be an efficient reagent for the synthesis of the target compounds.
ChemInform Abstract: Green Approach for Knoevenagel Condensation of Aromatic Aldehydes with Active Methylene Group.
Authors: Deshmukh M. B. , Patil Suresh S. , Jadhav S. D. , Pawar P. B. 
Published: July 2012

AbstractKnoevenagel condensation of aldehydes with malononitrile proceeds smoothly in lemon juice as solvent and catalyst.
ChemInform Abstract: Palladium‐Catalyzed C—H Alkenylation of Arenes Using Thioethers as Directing Groups.
Authors: Yu Ming , Xie Yongju , Xie Chunsong , Zhang Yuhong 
Published: July 2012

AbstractBenzylic thioethers are effective as directing group for the incorporation of various acrylates to arenes.
ChemInform Abstract: Highly Regioselective Synthesis of 1,3‐Diiodonaphthalene Derivatives via a Sequential Cascade Iodocyclization.
Authors: Wang Li‐Jing , Zhu Hai‐Tao , Lu Lei , Yang Fang , Liu Xue‐Yuan , Liang Yong‐Min 
Published: July 2012

AbstractThe use of 2.5 equiv.
ChemInform Abstract: Lewis Acid Catalyzed, Copper(II)‐Mediated Synthesis of Heteroaryl Thioethers under Base‐Free Conditions.
Authors: Dai Chao , Xu Zhaoqing , Huang Fei , Yu Zhengkun , Gao Yan‐Feng 
Published: July 2012

AbstractHeterocycles bearing medicinally important sulfur motifs are readily available with thiols or DMSO as the sulfurizing agents.
ChemInform Abstract: Environmentally Friendly Tetrahydrofuranylation of Alcohols Using NaHSO4—SiO2 under Solvent‐Free Conditions.
Authors: Kinfe Henok H. , Terblanche Sullivan , Tshivhase Konanani D. , Ravhura Livhuwani 
Published: July 2012

AbstractAdvantages of the title procedure are low cist, low catalyst loading, compatibility of the catalyst with a wide‐range of acid‐sensitive groups, short reaction times and the absence of organic solvents.
ChemInform Abstract: DBU‐Catalyzed Tandem Additions of Electron‐Deficient 1,3‐Conjugated Enynes with 2‐Aminomalonates: A Facile Access to Highly Substituted 2‐Pyrrolines.
Authors: Yu Xiuzhao , Zhou Guanghua , Zhang Junliang 
Published: July 2012

AbstractBoc‐ and Cbz‐protected amines can also be used as starting material.
ChemInform Abstract: Catalytic Enantioselective Synthesis of β‐Trifluoromethyl Pyrrolines.
Authors: Kawai Hiroyuki , Kitayama Takashi , Tokunaga Etsuko , Matsumoto Takashi , Sato Hiroyasu , Shiro Motoo , Shibata Norio 
Published: July 2012

AbstractThe first enantioselective synthesis of title compounds (III) and (V) is achieved via conjugate addition of nitromethane (II) to β‐trifluoromethylated enones (I) and (IV), resp., catalyzed by a bifunctional cinchona alkaloid—thiourea derivative, followed by a nitro reduction—cyclization—dehydration sequence in a one‐pot procedure.