bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of a non‐uniform scattering potential on conductance fluctuations in a quantum wire
Authors: Horsell D. W. , Galaktionov E. A. , Savchenko A. K. , Kretinin A. V. , Ghosh A. , Beere H. E. , Ritchie D. A. 
Published: January 2006

AbstractWe investigate experimentally the fluctuations of the conductance of a high mobility quantum wire. We show that scattering of electrons is not evenly distributed across the wire. In the centre of the wire electrons propagate almost ballistically. However, when the electrons are forced into the boundaries of the wire diffusive scattering occurs. This is seen as a dramatic enhancement of the variance and characteristic period of the fluctuations at the field at which maximum boundary scattering is predicted. We compare our results with recent theories and construct an empirical model to describe the transport processes in the wire. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crossover from strong to weak localization in the split‐off impurity band in two‐dimensional p ‐GaAs/AlGaAs structures
Authors: Agrinskaya N. V. , Kozub V. I. , Poloskin D. V. , Chernyaev A. V. , Shamshur D. V. 
Published: January 2006

AbstractA crossover from strongly localized behavior to weak localization (SL–WL) was observed in two‐dimensional modulation‐doped GaAs/Al0.3Ga0.7As structures as the impurity concentration increased. The low‐temperature dependence of the conductivity changed its character (from exponential to logarithmic) and the magnetoresistance changed its sign (from linear negative to root positive). For 2D structures, it is shown that this transition takes place in the impurity band separated from the valence band by the mobility gap whereas the effective mass in the impurity band is larger than in the valence band. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scaling at the energy‐driven metal‐insulator transition and the thermoelectric power
Authors: Croy Alexander , Römer Rudolf A. 
Published: January 2006

AbstractThe electronic properties of disordered systems at the Anderson metal‐insulator transition (MIT) have been the subject of intense study for several decades. Thermoelectric properties at the MIT, such as thermopower and thermal conductivity, however, have been relatively neglected. Using the recursive Green's function method and the Chester‐Thellung‐Kubo‐Greenwood formalism, we calculate numerically the low temperature behaviour of all kinetic coefficients Lij . From these we can deduce for example the electrical conductivity ω and the thermopower S at finite temperatures. Here we present results for the case of completely coherent transport in cubic 3D systems. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Antiferromagnetic phase in doped semiconductors near the insulator–metal phase transition
Authors: Veinger A. I. , Zabrodskii A. G. , Tisnek T. V. , Goloshchapov S. I. , Mokhov E. N. 
Published: January 2006

AbstractWe show for n ‐type semiconductors, using Ge:As and 4H ‐SiC:N as examples, that the spin density measured by electron spin resonance (ESR) falls sharply near the insulator–metal (IM) transition. Two reasons might be responsible for this phenomenon: potential fluctuations with concentration of the electrons in local minima or local antiferromagnetic spin pairing (“spin glass”) in the insulating state just below the IM transition. In the investigated semiconductors manifestation of the latter is observed as a change from Curie to a Curie–Weiss behaviour with negative constant Θ. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solution‐phase deuterium/hydrogen exchange at a specific residue using nozzle‐skimmer and electron capture dissociation mass spectrometry
Authors: Hagman Charlotte , Tsybin Yury O. , Håkansson Per 
Published: January 2006

AbstractInformation about protein conformation can be obtained with hydrogen/deuterium exchange (HDX) mass spectrometry. The isotopic solution‐phase exchange of specific amide hydrogen atoms can be followed using low‐vacuum nozzle‐skimmer collision‐induced dissociation (CID). In this study, the nozzle‐skimmer technique was complemented by electron capture dissociation (ECD) Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). The solution‐phase exchange at a specific residue is monitored by comparing isotopic distributions of two consecutive b‐ or c‐type ions. While nozzle‐skimmer fragmentation takes place in the low‐vacuum region of the mass spectrometer, ECD occurs at ultra‐high vacuum within the mass analyzer cell of the FTICR mass spectrometer. The dissociations take place at 10−4 and 10−9 mbar, respectively. Low‐vacuum nozzle‐skimmer fragmentation can result in intramolecular exchange between product ions and solvent molecules in the gas phase. Consequently, the solution‐phase information about protein or peptide conformation is lost. It was not possible to monitor isotopic solution‐phase exchange at the eighth residue in substance P, (Phe)8, with nozzle‐skimmer CID. By using the in‐cell ECD fragmentation method, the solution‐phase exchange at the (Phe)8 residue was preserved during mass spectrometric analysis. This result shows the complementary aspects of applying fragmentation at low and at high vacuum, when studying isotopic exchange in solution at specific residues using FTICRMS. Copyright © 2006 John Wiley & Sons, Ltd.
Monitoring enzyme‐catalyzed production of glucosamine‐6P by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry: a new enzymatic assay for glucosamine‐6P synthase
Authors: Maillard Ludovic T. , Guérineau Vincent , Badet‐Denisot Marie‐Ange , Badet Bernard , Laprévote Olivier , Durand Philippe 
Published: January 2006

AbstractA matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) method for quantification of D‐glucosamine‐6P (GlcN‐6P) that allows the kinetic study of glucosamine‐6P synthase (Glms) is presented. The present report describes the optimization of the different steps of a new enzymatic assay for Glms based on in situ N‐acetylation of GlcN‐6P and MALDI‐TOFMS analysis using N‐(13C2)acetylglucosamine‐6P as internal standard. Since no isotopically substituted GlcN‐6P was available, the N‐(13C2)acetyl derivative, easily obtained from (13C4)‐acetic anhydride, was used as internal standard. Validation of the assay was achieved by measuring the fructose‐6P Michaelis constant, in full agreement with reported values, and by studying the inhibition properties of arabinose‐5P oxime. Copyright © 2006 John Wiley & Sons, Ltd.
Structural analysis of secondary ions by post‐source decay in time‐of‐flight secondary ion mass spectrometry
Authors: Touboul David , Brunelle Alain , Laprévote Olivier 
Published: January 2006

AbstractTandem mass spectrometry measurements have been achieved using time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) and a post source decay (PSD)‐like method. The performance of the method has been demonstrated on model molecules with well‐known fragmentation pathways. Several lipids have been fragmented including the phosphocholine ion, phosphatidylcholines, cholesterol and vitamin E. Pure samples were analyzed, and the results compared with those obtained with the same compounds on a quadrupole‐TOF hybrid mass spectrometer. Then, the structures of some lipids which are currently observed in the TOF‐SIMS imaging of mammalian tissue sections were verified. Copyright © 2006 John Wiley & Sons, Ltd.
Investigation of vancomycin and related substances by liquid chromatography/ion trap mass spectrometry
Authors: Diana J. , Visky D. , Hoogmartens J. , Van Schepdael A. , Adams E. 
Published: January 2006

AbstractLiquid chromatography (LC) methods compatible with mass spectrometry (MS) that are suitable for impurity profiling of vancomycin mixtures have not been described in the literature. The mobile phases of the existing methods contain non‐volatile additives and/or solvents that give problems in combination with MS. In this paper, a reversed‐phase LC/tandem mass spectrometry method is described for the investigation of vancomycin and related substances. The LC method uses a Zorbax Extend C18 column (250 × 4.6 mm i.d.), 5 µm, and a mobile phase consisting of methanol, water and ammonium acetate solution (pH 9.0). This method allows us to separate vancomycin and its impurities. Mass spectral data are acquired on an LCQ ion trap mass spectrometer equipped with an electrospray interface operated in the positive and negative ion modes. The LCQ is ideally suited for identification of impurities and related substances because it provides on‐line LC/MSn capability, which allows efficient identification without time‐consuming isolation and purification procedures. Using this method, the fragmentation of vancomycin and known derivatives was studied and the structures of six substances occurring in commercial samples were elucidated. Copyright © 2006 John Wiley & Sons, Ltd.
Combined Atomic Force Microscopy and Optical Microscopy Measurements as a Method To Investigate Particle Uptake by Cells
Authors: Muñoz Javier Almudena , Kreft Oliver , Piera Alberola Alicia , Kirchner Christian , Zebli Bernd , Susha Andrei S. , Horn Elias , Kempter Susanne , Skirtach Andre G. , Rogach Andrey L. , Rädler Joachim , Sukhorukov Gleb B. , Benoit Martin , Parak Wolfgang J. 
Published: January 2006

AbstractWe propose a combination of atomic force microscopy (AFM) and optical microscopy for the investigation of particle uptake by cells. Positively and negatively charged polymer microcapsules were chosen as model particles, because their interaction with cells had already been investigated in detail. AFM measurements allowed the recording of adhesion forces on a single‐molecule level. Due to the micrometer size of the capsules, the number of ingested capsules could be counted by optical microscopy. The combination of both methods allowed combined measurement of the adhesion forces and the uptake rate for the same model particle. As a demonstration of this system, the correlation between the adhesion of positively or negatively charged polymer microcapsules onto cell surfaces and the uptake of these microcapsules by cells has been investigated for several cell lines. As is to be expected, we find a correlation between both processes, which is in agreement with adsorption‐dependent uptake of the polymer microcapsules by cells.
Chemical Mapping of Individual Semiconductor Nanostructures
Authors: Ratto Fulvio , Locatelli Andrea , Fontana Stefano , Kharrazi Sharmin , Ashtaputre Shriwas , Kulkarni Sulabha K. , Heun Stefan , Rosei Federico 
Published: January 2006

AbstractWe demonstrate experimentally the power of a novel analytical tool for X‐ray spectromicroscopy. This provides a minimally intrusive elemental mapping of surfaces at the nanoscale and holds the promise of remarkable versatility. We have applied our procedure to the characterization of Ge(Si) islands on Si(111) substrates, with the aim of investigating the surface stoichiometry gradients and gaining insight into the intermixing dynamics. By identifying Si‐richer edges with respect to the centers, we are able to associate alloying in these islands to surface transport processes.
Hochtemperatur‐Festkörperchemie: Der Niederdruck‐Hochfrequenz‐Plasmabrenner: Synthese stabiler und metastabile Oxometallate der Lanthanoide
Authors: Müller‐Buschbaum Hanskarl 
Published: January 2006

AbstractHigh Temperature Solid State Chemistry. The Low Pressure High Frequency‐Plasmaburner: Synthesis of Stable and Metastable Oxometalates of Rare Earth OxidesReactions between high temperature refractory oxides (Alkaline Earth oxides and Rare Earth oxides) always require exceptionally high temperatures for the synthesis of new compounds, especially for the preparation of single crystals. It will be shown, that conventional electrical heaters on the base of resistance heating don't achieve the melting points of refractory oxides. Other methods like solar radiation, electron beam heating ore hot flames (oxyhydrogen / oxyacetylene welding torch) are discussed. In the middle of the sixties of last century the open high pressure and the closed low pressure HF‐plasma burners had been developed. The following contribution gives once attention to the discovery and application of the closed low pressure plasma burner. In this paper the synthesis of stable and metastable (entropy stabilized) compounds (> 2000 °C) between Alkaline Earth and Rare Earth Oxides is shown. In detail the contribution makes clear how to prepare stable (CaFe2O4‐type) and metastable compounds of the composition AM2O4 (SrCr2O4, α‐CaCr2O4, BaCr2O4). These prototypes are the basis for micro space disordered compounds like SrCa2Ln6O12, SrCa2Ln10O18 and BaSrCaLn22O23. Using high temperature synthesis the thermodynamic stable compound SrNd2O4 altered to the metastable Sr3Nd4O7‐type. On the other hand the formation of BaLn2O4 does not occur for the heavy Rare Earth elements. Instead of the well‐known CaFe2O4‐type a complicated new stable structure type of the composition Ba3Ln4O9 is created.The closed high frequency plasma burner makes possible to reinvestigate the “dissolution” of Alkaline Earth oxides in Rare Earth oxides aid of single crystals. A typical example is the formation of Ln2−xCaxO3−x. Starting with cubic Ho2O3 (C‐form) small values of x (x<0,2) stabilize the monoclinic form (B‐Form) of Rare Earth oxides (B‐Ho2−xCaxO3−x). For compositions 1.0 ≥ x ≥ 0.2 the monoclinic B‐form of Rare Earth oxides is left in favour of a new structure type Ca2Ho2O5. It may by regard as modified monoclinic B‐form with a statistically distributed deficiency of oxygen.In the end the importance of atomic hydrogen, produced by high temperatures of plasma torches, is shown in case of the reduction of TiO2 and in case of the formation of Eu2+, stabilized by compounds of the composition Eu2+BeLn2O5.
Ein Licht emittierender Imidazol‐substituierter 2,2'‐Bipyridin‐Ruthenium(II)‐Komplex als Sensorfür die Reaktion von Protonen und Metallionen am peripheren Imidazolring
Authors: Schramm Frank , Görls Helmar , Walther Dirk 
Published: January 2006

AbstractA Light Emitting Imidazole Substituted 2,2'‐Bipyridin Ruthenium(II) Complex as a Sensor for Reactions of Protons and Metal ions on the Peripheral Imidazole RingRuthenium(II) complexes of the type [(tbbpy)2Ru(L‐L)](PF6)2 (tbbpy = bis‐4,4'‐di‐tert‐butyl‐2,2'‐bipyridine; 1: L‐L = 5‐(N‐ethoxymethyl‐1H‐imidazol‐2‐yl)‐[2,2']bipyridine; 2: L‐L = 1H‐imidazol‐2‐yl)‐[2,2']bipyridine) were prepared from [(tbbpy)2RuCl2] and the chelate ligands L‐L followed by treatment with NH4[PF6]. Characterization occurred by ESI‐MS, 1H‐ und 13C NMR spectroscopy. The molecular structure of 2, crystallized with five water molecules, was determined by an X‐ray diffraction analysis. The ruthenium(II) ion is surrounded distorted octahedral by the six N‐donor ligand atoms of the chelate ligands and two complex molecules are connected via the water molecules which form a hydrogen bonded network with the two nitrogen atoms of the peripheral imidazole ring.The water‐free complex 2 in THF emits light at room temperature. Both, the deprotonation and the protonation of the peripheral imidazole ring results in systems which show extremely weak emission intensity only. Also, the interaction of 2 with water decreases the intensity of the emission. The coordination of metal ions at the imidazole ring of 2 or at the imidazolate ring of the deprotonated species 2a is indicated by an increase of the emission intensity and the change of the emission maxima.
Synthesis and Characterization of a New Three‐dimensional Organically Templated Nickel‐Zinc Phosphate
Authors: Lin Zhi‐En , Fan Wei , Chino Naotaka , Gao Feifei , Yokoi Toshiyuki , Okubo Tatsuya 
Published: January 2006

AbstractA new organically templated nickel–zinc phosphate, [C2N2H10]·[Ni2.4Zn3.6(PO4)4(HPO4)]·H2O, has been synthesized from an aqueous solution containing NiCl2·6H2O, Zn(OAc)2·2H2O, H3PO4 and ethylenediamine as the structure‐directing agent. The compound crystallizes in the monoclinic system, space group C2/c (No. 15), a = 19.1563(5), b = 5.0316(2), c = 21.1724(5) Å, α = 103.201(3)°, V = 1986.81(11) Å3, Z = 4. It possesses a three‐dimensional framework constructed from MO4 (M = Ni, Zn), PO4, and HPO4 tetrahedra through their vertices. One‐dimensional 8‐ring channels are found in the structure, with the diprotonated organic templates residing in the tunnels and interacting with the inorganic framework by extensive hydrogen bonds. The framework is characterized by infinite helical chains of corner‐sharing MO4 (M = Ni, Zn) tetrahedra.
Structural and Spectroscopic Characterization of Ammonium Thiosaccharinate Monohydrate
Authors: Baran Enrique J. , Piro Oscar E. , Zinczuk Juan 
Published: January 2006

AbstractThe crystal structure of NH4[tsac]·H2O (tsac = anion of the thiosaccharin molecule) has been determined by single crystal X‐ray diffractometry. It crystallizes in the orthorhombic space group Pbca with Z = 8. The infrared spectrum of the compound was also recorded and its most important features discussed on the basis of its structural peculiarities.
A Novel Huge Diamond‐like Three‐fold Interpenetrated Network of CuI and Crown Ether
Authors: Heller Maik 
Published: January 2006

AbstractThe quest for mercury sensitive ion exchangers results in a diamondlike network $^{3}_{\infty}\rm [(CUI)_{2}(1,10DT18C6)]$ (1). This is in contrast to the similar well known 44 network $^{2}_{\infty}\rm [(CUI)(1,10DT18C6)]$ described by Röttgers and Sheldrick [1] a 3D strucutre. 1 is accessible by treatment of CuI with 1,10‐dithia‐18‐crown‐6 in acetonitrile solution in a sealed glass tube in the presence of HgI, but it doesn't contain mercury at all. It seems that either the presence of mercury salts or the excess of iodine ions plays a catalytic role, which is not clarified yet. The main building blocks of 1 are distorted cubes of CuI, which are linked with crown ether rods to give an adamantanlike structure. The space inside the diamondlike network is filled by interpenetration with in sum three similar networks. The longest distance between oppositely CuI cubes in the adamantanlike building block is with 44.796(9) Å three times the b axis.
Ion Pairing, H‐bonding, and π‐π Interactions in Cobalt(II) Compound Containing Guanidinium Counter Ion
Authors: Sheshmani Shabnam , Aghabozorg Hossein , Panah Fahimeh Mohammad , Alizadeh Robabeh , Kickelbick Guido , Nakhjavan Bahar , Moghimi Abolghasem , Ramezanipour Farshid , Aghabozorg Hamid Reza 
Published: January 2006

AbstractA novel proton transfer compound, (GH)2(phendc), (1), was synthesized from the reaction of 1,10‐phenanthroline‐2,9‐dicarboxylic acid, phendcH2, and guanidine hydrochloride, (GH)(Cl), (G: guanidine). The characterization was performed using IR, 1H and 13C NMR spectroscopy. The cobalt(II) compounds were synthesized using proton transfer compounds containing guanidinium counter ion. These proton transfer compounds are (GH)2(phendc), and (GH)2(pydc) (pydcH2: 2,6‐pyridinedicarboxylic acid). The chemical formulae and space groups are (GH)2[Co(phendc)2]·4H2O, $P{\bar 1}$ (2), and (GH)2[Co(H2O)6][Co(pydc)2]2, P21/n (3). Non‐covalent interactions such as ionpairing, hydrogen bonding and π‐π stacking are discussed.
Comment on the Paper: “Synthesis and Electrochemical Study of Antifluorite‐type Phases in the Li‐M‐N‐O (M = Ti, V) Systems” [1]
Authors: Niewa Rainer , Zherebtsov Dmitry A. 
Published: January 2006

AbstractBased on experimental data it is shown that samples in a solid solution series of the system Li7[VN4]–Li2O with partial Li–V order can be obtained.
Answer to the Comment submitted by R. Niewa and D. A. Zherebtsov on the Paper “Synthesis and Electrochemical Study of Antifluorite‐type Phases in the Li‐M‐N‐O (M = Ti, V) Systems” [1]
Authors: Palacín M. R. 
Published: January 2006

AbstractIn the reaction conditions leading to γ‐Li7VN4, no ordered solid solution γ‐Li7VN4–Li2O seems to exist but rather a mixture of two phases: γ‐Li7VN4 and a lithium vanadium oxynitride with the disordered anti‐fluorite structure. Even though the trend may be different in the case of β‐Li7VN4–Li2O, neutron diffraction experiments would be desirable to confirm/dismiss these assumptions, as they would allow to determine the number of phases and polymorphs present and the degree of Li/V or N/O order, if any.
Ein neues cis‐[Bi3I12]3−‐Anion in Tri(n‐butyl)methylammonium Dodecaiodotribismutat
Authors: Okrut A. , Feldmann C. 
Published: January 2006

AbstractThe Novel cis‐[Bi3I12]3−‐Anion in Tri(n‐butyl)methylammoniumdodecaiodo‐tribismutateBy reaction of equivalent amounts of BiI3, KI and I2 in [N(CH3) (n‐C4H9)3][N(SO2CF3)2] as Ionic Liquid, transparent reddish crystals with the composition [N(CH3)(n‐C4H9)3]3[Bi3I12] are formed. Concerning to X‐ray diffraction investigations based on single crystals as well as powders, [N(CH3)(n‐C4H9)3]3[Bi3I12] crystallizes monoclinic (P21/c; a = 2383.0(5); b = 1241.0(3); c = 2493.0(5) pm; β = 97.50(3)°; Z = 4). The anion consists of distorted (BiI6)‐octahedra, which are face‐shared via cis‐oriented octahedral faces. With the cis‐[Bi3I12]3−‐anion such a connectivity is firstly described.
Two Novel Three‐Dimensional Lead(II) Coordination Polymers Involving 16‐Membered Rings: [Pb2(Bs‐glu)2(bipy)2] and [Pb2(Bs‐glu)2(phen)2]
Authors: Ma Lu‐Fang , Wang Li‐Ya , Wang Jian‐Ge , Wang Yu‐Fang , Feng Xun 
Published: January 2006

AbstractThe reaction of Pb(CH3COO)2·3H2O with N‐benzesulfonyl‐L‐glutamic acid in the presence of 2, 2′‐bipyridine (bipy) or 1,10‐phenanthroline (phen) produced two novel complexes [Pb2(Bs‐glu)2(bipy)2] (1) and [Pb2(Bs‐glu)2(phen)2] (2) (Bs‐glu = N‐benzesulfonyl‐L‐glutamic acid dianion). In 1 chains bearing alternative 16‐membered rings and Pb2O3 nodes are constructed from the interactions of PbII ions with the carboxylates of Bs‐glu ligands. To the best of our knowledge, this is the first lead(II) complex of carboxylates with the formation of chains of Pb2O3. In 2 the 16‐membered ring units are connected by centrosymmetric Pb2O2 nodes to form chains. Complexes 1 and 2 construct the 3‐D supramolecular architectures through versatile hydrogen bonds and π‐π stacking interactions.
Crystal Structure of μ‐Oxo‐bis[9,22‐(bisbutyloxy)hemiporphyrazinato]iron(III)
Authors: Haberroth Klaus , Hanack Michael , Maichle‐Mössmer Cäcilia 
Published: January 2006

AbstractThe crystal structure of the title compound, C68H60N16O5Fe2, shows a dinuclear complex of two crystallographically independent, distorted hemiporphrazinato iron complexes with five‐coordinate iron and oxygen as bridging ligand. The Fe1‐O1‐Fe2 angle is 151.16°, the Fe‐O bond lengths are Fe1‐O1 [1.771(2) Å] and Fe2‐O1 [1.773(2) Å]. The dinuclear complexes have a staggered conformation with a dihedral angle of 26.2°, but coaxially to form tetrameric units is not observed. The molecule is characterized by short Fe‐N (isoindole) bonds [1.998(3) Å] and long Fe‐N (pyridine) bonds, values range from [2.175(3) Å] to [2.245(3) Å].
Crystal Structure and Spectroscopic Characterization of Lithium Saccharinate 11/6 Hydrate, a Hygroscopic and Potentially Physiologically Active Compound
Authors: Naumov Pancče , Jovanovski Gligor , Tancčeva Slavica , Ng Seik Weng 
Published: January 2006

AbstractThe structure of the only structurally yet uncharacterized alkali saccharinate, lithium saccharinate, is reported, together with the infrared spectra of its protonated and partially deuterated analogues. The compound crystallizes as strongly hygroscopic colorless triclinic crystal blocks of a 11/6 hydrate, LiC7H4NO3S·11/6H2O, space group $P{\bar 1}$, with unit cell dimensions a = 10.070(1), b = 15.755(2), c = 19.134(2) Å, α = 68.085(2), β = 76.940(2), γ = 84.169(2)°, V = 2743.0(5) Å3 and Z = 12 at T = 200(2) K.