bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental and quantum‐chemical studies of 1H, 13C and 15N NMR coordination shifts in Pd(II) and Pt(II) chloride complexes with methyl and phenyl derivatives of 2,2′‐bipyridine and 1,10‐phenanthroline
Authors: Pazderski Leszek , Toušek Jaromír , Sitkowski Jerzy , Kozerski Lech , Szłyk Edward 
Published: November 2007

Abstract1H, 13C and 15N NMR studies of platinide(II) (M = Pd, Pt) chloride complexes with methyl and phenyl derivatives of 2,2′‐bipyridine and 1,10‐phenanthroline [LL = 4,4′‐dimethyl‐2,2′‐bipyridine (dmbpy); 4,4′‐diphenyl‐2,2′‐bipyridine (dpbpy); 4,7‐dimethyl‐1,10‐phenanthroline (dmphen); 4,7‐diphenyl‐1,10‐phenanthroline (dpphen)] having a general [M(LL)Cl2] formula were performed and the respective chemical shifts (δ1H, δ13C, δ15N) reported. 1H high‐frequency coordination shifts (Δ1Hcoord = δ1Hcomplex − δ1Hligand) were discussed in relation to the changes of diamagnetic contribution in the relevant 1H shielding constants. The comparison to literature data for similar [M(LL)(XX)], [M(LL)X2] and [M(LL)XY] coordination or organometallic compounds containing various auxiliary ligands revealed a large dependence of δ1H parameters on inductive and anisotropic effects. 15N low‐frequency coordination shifts (Δ15Ncoord = δ15Ncomplex − δ15Nligand) of ca 88–96 ppm for M = Pd and ca 103–111 ppm for M = Pt were attributed to both the decrease of the absolute value of paramagnetic contribution and the increase of the diamagnetic term in the expression for 15N shielding constants. The absolute magnitude of Δ15Ncoord parameter increased by ca 15 ppm upon Pd(II) → Pt(II) transition and by ca 6–7 ppm following dmbpy → dmphen or dpbpy → dpphen ligand replacement; variations between analogous complexes containing methyl and phenyl ligands (dmbpy vs dpbpy; dmphen vs dpphen) did not exceed ± 1.5 ppm. Experimental 1H, 13C, 15N NMR chemical shifts were compared to those quantum‐chemically calculated by B3LYP/LanL2DZ + 6–31G**//B3LYP/LanL2DZ + 6–31G*, both in vacuo and in DMSO or DMF solution. Copyright © 2007 John Wiley & Sons, Ltd.
Intracellular water specific MR of microbead‐adherent cells: Hela cell intracellular water diffusion
Authors: Zhao L. , Sukstanskii A. L. , Kroenke C. D. , Song J. , Piwnica‐Worms D. , Ackerman J. J. H. , Neil J. J. 
Published: November 2007

AbstractThe 1H MR signal arising from flowing extracellular media in a perfused, microbead‐adherent cultured cell system can be suppressed with a slice‐selective, spin‐echo pulse sequence. The signal from intracellular water can, thus, be selectively monitored. Herein, this technique was combined with pulsed field gradients (PFGs) to quantify intracellular water diffusion in HeLa cells. The intracellular water MR diffusion‐signal attenuation at various diffusion times was well described by a biophysical model that characterizes the incoherent displacement of intracellular water as a truncated Gaussian distribution of apparent diffusion coefficients (ADCs). At short diffusion times, the water “free” diffusion coefficient and the surface‐to‐volume ratio of HeLa cells were estimated and were, 2.0 ± 0.3 μm2/ms and 0.48 ± 0.1 μm−1 (mean ± SD), respectively. At long diffusion times, the cell radius of 10.1 ± 0.4 μm was inferred and was consistent with that measured by optical microscopy. In summary: 1) intracellular water “free” diffusion in HeLa cells was rapid, two‐thirds that of pure water; and 2) the cell radius inferred from modeling the incoherent displacement of intracellular water by a truncated Gaussian distribution of ADCs was confirmed by independent optical microscopy measures. Magn Reson Med 57, 2007. © 2007 Wiley‐Liss, Inc.
Research capacity building through twinning: experiences from a Danish–Malaysian twinning project
Authors: Jensen Marina Bergen , Hjortsø Carsten Nico , Schipperijn Jasper , Nik Abdul‐Rahim , Nilsson Kjell 
Published: November 2007

AbstractTwinning and its contribution to institutional capacity building in developing countries is the theme of an ongoing debate in Public Administration and Development. Unlike earlier contributions this article focuses on twinning in the context of research capacity enhancement. Using a 3 year Danish–Malaysian twinning research project as case our objective is to evaluate whether the general premises regarding a twinning project, as formulated by the Danish Development Cooperation Agency (Danida), appropriately support the twinning ambitions when the capacities in focus concern research. Besides institutional capacity building, twinning is expected to favour local ownership, involvement of the Danish resource base and continuing of cooperation after termination of funding. From 21 semi‐structured interviews with project participants it was found that although new research capacities had been gained, the prospects on continued cooperation are rather discouraging, both sides pointing to the lack of truly joint research experiences as the main reason. To care for this important incentive, the twinning premises are recommended to be modified to allow for the Northern resource base to advance its own research, and for Southern partner to demonstrate in‐house research capacities. Further, the North–South balance in project management needs to be more equal. This apart, the twinning premises appear sound. Copyright © 2007 John Wiley & Sons, Ltd.
Recent methodology in the phytochemical analysis of ginseng
Authors: Angelova Nadezhda , Kong Hong‐Wei , van der Heijden Rob , Yang Shih‐Ying , Choi Young Hae , Kim Hye Kyong , Wang Mei , Hankemeier Thomas , van der Greef Jan , Xu Guowang , Verpoorte Rob 
Published: November 2007

AbstractThis review summarises the most recent developments in ginseng analysis, in particular the novel approaches in sample pre‐treatment and the use of high‐performance liquid‐chromatography–mass spectrometry. The review also presents novel data on analysing ginseng extracts by nuclear magnetic resonance spectroscopy and high‐resolution mass spectrometry (Fourier transform mass spectrometry) in the context of metabolomics. Copyright © 2007 John Wiley & Sons, Ltd.
Optimised Dirac operators on the lattice: construction, properties and applications
Authors: Bietenholz W. 
Published: November 2007

AbstractWe review a number of topics related to block variable renormalisation group transformations of quantum fields on the lattice, and to the emerging perfect lattice actions. We first illustrate this procedure by considering scalar fields. Then we proceed to lattice fermions, where we discuss perfect actions for free fields, for the Gross‐Neveu model and for a supersymmetric spin model. We also consider the extension to perfect lattice perturbation theory, in particular regarding the axial anomaly and the quark gluon vertex function. Next we deal with properties and applications of truncated perfect fermions, and their chiral correction by means of the overlap formula. This yields a formulation of lattice fermions, which combines exact chiral symmetry with an optimisation of further essential properties. We summarise simulation results for these so‐called overlap‐hypercube fermions in the two‐flavour Schwinger model and in quenched QCD. In the latter framework we establish a link to Chiral Perturbation Theory, both, in thep‐regime and in the ϵ‐regime. In particular we present an evaluation of the leading Low Energy Constants of the chiral Lagrangian – the chiral condensate and the pion decay constant – from QCD simulations with extremely light quarks.
Impact of strain on scaling of Double Gate nanoMOSFETs using NEGF approach
Authors: Martinez A. , Kalna K. , Svizhenko A. , Anantram M. P. , Barker J. R. , Asenov A. 
Published: November 2007

AbstractThe effect of biaxial strain on double gate (DG) nanoscaled MOSFET with channel lengths in the nanometre range is investigated using Non‐Equilibrium Green's Functions (NEGF) simulations. The NEGF simulations are fully 2D in order to accurately evaluate the effects of strain in strongly confined channels. Starting with a 14 nm gate length DG MOSFET with a corresponding body thickness of 9 nm we scale the transistors to gate lengths of 10, 6 and 4 nm and body thicknesses of 6.1, 2.6 and 1.3 nm, respectively. The simulated ID‐VG characteristics show 11% improvement in the oncurrent for the 14 nm gate length transistor due to theΔvalley splitting. This improvement in the on‐current is due to separate contributions from the 2 fold and 4 fold valleys to the carrier transport. However, in the device with an extreme body thickness of 1.3 nm the strain has no impact on its performance because the strong confinement itself produces a large valley splitting. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quo Vadis Nanoelectronics?
Authors: Ferry D. K. 
Published: November 2007

AbstractSemiconductor devices continue to be downscaled on a regular basis as technology provides the ability to make smaller dimensions via improved lithography, a process which is known as Moore's Law. However, the driving force for the continued increase in number of devices on a chip is not this reduction in size, but the ability to put more functions on a chip with the same cost per unit area of Si. Nevertheless, it is not clear that our technology for Si devices can continue to work much longer. Here, I will discuss the driving forces, including energy dissipation, speed, area, and technological factors for the projected end‐of‐the roadmap technology. Yet, there continues to be a search for new device technologies to supplement, or replace, Si CMOS. Quantum wires have been sug‐gested in many places as a possible new technology that can provide many opportunities for enhancing chip architecture. But, the constraints on any new technology can be viewed in terms of Si cost, and the manner in which new approaches to devices can be pursued will be dis‐cussed. Some possible technologies are FinFETs, vertical quantum wires, carbon nanotubes, III‐Vs, and similar ap‐proaches. Device downsizing is only one of three driving forces that lead to Moore's Law, with increasing chip size and circuit cleverness playing an equal part. This suggests that many novel devices should not be viewed as competition to CMOS, but in the light of how they may modify the circuit architecture. Indeed, circuit clev‐erness has been as important in managing breakthroughs in the past as new processing technology. Some new op‐portunities, that arise from the nature of nanowire fabri‐cation, in these novel devices may lead to breakthroughs in the area of circuit cleverness. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Understanding selenocysteine through conformational analysis, proton affinities, acidities and bond dissociation energies
Authors: Kaur Damanjit , Sharma Punita , Bharatam Prasad V. , Kaur Mondeep 
Published: November 2007

AbstractDensity functional methods have been employed to characterize the gas phase conformations of selenocysteine. The 33 stable conformers of selenocysteine have been located on the potential energy surface using density functional B3LYP/6‐31+G* method. The conformers are analyzed in terms of intramolecular hydrogen bonding interactions. The proton affinity, gas phase acidities, and bond dissociation energies have also been evaluated for different reactive sites of selenocysteine for the five lowest energy conformers at B3LYP/6‐311++G*//B3LYP/6‐31+G* level. Evaluation of these intrinsic properties reflects the antioxidant activity of selenium in selenocysteine. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
α4/3 Conotoxins: phylogenetic distribution, functional properties, and structure–function insights
Authors: Ellison Michael , Olivera Baldomero M. 
Published: November 2007

AbstractThis review examines the α4/3 conotoxins as an example of molecular diversity in a class of compounds that have evolved in a group of closely related species in a single phylogenetic lineage. The species examined belong to Stephanoconus, a clade of Conus, a genus that contains 500–700 different species of carnivorous marine snails. We examine earlier work that describes the identification and characterization of α‐ImI, the founding α4/3 toxin, and two other α4/3 toxins, α‐ImII and α‐RgIA. These three toxins all inhibit nicotinic acetylcholine receptors (nAChRs) belonging to a subset of nAChRs that are composed of only α subunits; they are, however, diverse in terms of the all‐α subtype they preferentially antagonize and the receptor site that they bind to. We thus speculate that the α4/3 toxins may be a rich source of functionally diverse all‐α subunit nAChR inhibitors. We review extensive work that has established a detailed model for α‐ImI binding to one of its preferred nAChR subtypes (the α7 nAChR) and, by comparing the α‐ImI, α‐ImII and α‐RgIA sequences demonstrate how structural features of α4/3 peptides that account for their diverse functional properties can be identified. This approach is extended to derive models of receptor‐toxin binding that may account for the different subtype specificities of α4/3 peptides. We also speculate on how rational modification of α4/3 toxins may allow engineering of ligands with desired subtype specificities. The chemical diversity produced by the closely related animals in Stephanoconus is thus functionally differentiated, although structurally homologous. © 2007 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 7: 341–353; 2007: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20131
[{LiCH(CH2CH2OMen)SO2Ph}4] (OMen = Menthyl): Synthesis and First Structure of a Chiral Solvent Free Lithiated Sulfone with a Direct Li–C Bond
Authors: Linnert Matthias , Wagner Christoph , Merzweiler Kurt , Steinborn Dirk 
Published: November 2007

AbstractR*OCH2CH2CH2SO2Ph (R*OH = MenOH, (–)‐menthol, (3a); BorOH, (1S)‐(–)‐borneol, (3b)) were found to react with n‐BuLi in n‐pentane/n‐hexane and toluene/n‐hexane under deprotonation yielding LiCH(CH2CH2OR*)SO2Ph (R* = Men, (4a); Bor, (4b)) which reacted with n‐Bu3SnCl forming the requisite tri(n‐butyl)tin compounds n‐Bu3SnCH(CH2CH2OR*)SO2Ph (R* = Men, (5a); Bor, (5b)) as diastereomeric mixtures. The identities of 5a and 5b were unambiguously proved by 1H, 13C and 119Sn NMR spectroscopic measurements. Solutions of 4a afforded crystals of [{LiCH(CH2CH2OMen)SO2Ph}4] (4a′) for which the structure was determined by single‐crystal X‐ray crystallography. Complex 4a′ crystallized in a tetrameric structure without any additional solvent molecules. There were found direct Li–C bonds (Li1–C1/Li2–C20 2.231(9)/2.236(9) Å). The tetrahedral donor set of Li is completed by three oxygen atoms. One oxygen atom comes from the OMen substituent via intramolecular coordination and two oxygen atoms come from SO2 groups of neighboured LiCH(CH2CH2OMen)SO2Ph moieties. Thus, a heterocubane structure with a Li4S4 core is built up.
La4B14O27: Ein Lanthan‐ultra‐Oxoborat mit Raumnetzstruktur
Authors: Nikelski Tanja , Schäfer Marion C. , Schleid Thomas 
Published: November 2007

AbstractLa4B14O27: A Lanthanum ultra‐Oxoborate with a Framework StructureSingle crystals of La4B14O27 could be synthesized by the reaction of La2O3, LaCl3 and B2O3 with an access of CsCl as fluxing agent in gastightly sealed platinum ampoules within twenty days at 710 °C and appear as colourless, transparent and waterresistant platelets. The new lanthanum oxoborate La4B14O27 (monoclinic, C2/c; a = 1120.84(9), b = 641.98(6), c = 2537.2(2) pm, β = 100.125(8)°; Z = 4) is built of a three‐dimensional boron‐oxygen framework containing seven crystallographically different boron atoms. Four of these B3+ cations are surrounded by four O2− anions tetrahedrally, whereas the other three have only three oxygen neighbours with nearly plane triangular coordination figures. Three of the [BO4]5− tetrahedra form [B3O9]9− rings by cyclic vertex‐condensation, which are further linked via [BO3]3− units to infinite layers. Two of these layers connect via one [B2O7]8− unit of two corner‐shared [BO4]5− tetrahedra to double layers, which themselves build up a three‐dimensional framework together with chains consisting of two [BO4]5− tetrahedra and one [BO3]3− triangle. One of the two crystallographically independent La3+ cations (La1) is surrounded by ten O2− anions and resides within the oxoborate double layers. (La2)3+ shows a (8+2)‐fold coordination of O2− anions and occupies channels along the [110] direction.
A Widely Applicable Synthetic Approach to Alk‐1‐yn‐1‐yl(polyfluoroorganyl)‐iodonium Salts [(RC≡C)(R′)I][BF4]
Authors: Frohn Hermann‐Josef , Bardin Vadim V. 
Published: November 2007

AbstractThe reaction of alkynyldifluoroboranes RC≡CBF2 (R = (CH3)3C, CF3, (CF3)2CF) with organyliodine difluoride R′IF2 bearing electron‐withdrawing polyfluoroorganyl groups R′ = C6F5, (CF3)2CFCF=CF, C4F9, and CF3CH2 leads to the corresponding alkynyl(organyl)iodonium salts [(RC≡C)(R′)I][BF4]. This approach uses a widely applicable method as demonstrated for a representative series of polyfluorinated aryl‐, alkenyl‐, and alkyliodine difluorides. Generally, these syntheses proceed with good yields and deliver pure iodonium salts. The distinct electrophilic nature of their [(RC≡C)(R′)I]+ cations is deduced from multinuclear magnetic resonance data. Within the series of new iodonium salts [CF3C≡C(C4F9)I][BF4] is an intrinsic unstable one and decomposed forming CF3C≡CI and C4F10.
The Cluster Polymers $^{1}_{\infty}\rm [PtBi_{6}Cl_{10}]$ and $^{1}_{\infty}\rm [PtBi_{6}Br_{10}]$: Synthesis, Thermochemistry, Crystal Structure and Chemical Bonding
Authors: Steden Folker , Schmidt Peer , Wahl Bernhard , Isaeva Anna , Ruck Michael 
Published: November 2007

AbstractThe reaction of Bi, Pt and BiX3 (X = Cl, Br) in an inert flux of AlX3 yields black crystals of the subhalides PtBi6X10. The compounds can also be obtained from the cluster salts Bi2/3[PtBi6X12] by abstracting ⅔ equivalents of BiX3. Consequently, the formation of PtBi6X10 is favored at higher temperatures when the vapor pressure p(BiX3) evolved from Bi2/3[PtBi6X12] is high. In accordance with the experimental results a quantitative thermodynamic description of the system Bi/Pt/Cl is given. X‐ray diffraction on single‐crystals at 293 K revealed that the two PtBi6X10 compounds crystallize isostructurally in the orthorhombic space group Pnma with a = 1631.4(1)/1682.39(5) pm, b = 2667.8(2)/2731.1(1) pm and c = 906.9(1)/978.30(4) pm for X = Cl/Br. The fundamental motif of the structure is the cuboctahedral [PtBi6X12] cluster, in which the platinum atom centers an octahedron of bismuth atoms whose edges are bridged by twelve halogen atoms. By sharing two halogen atoms with in each case the two neighbors the clusters are concatenated into a cis‐trans chain $^{1}_{\infty}{\rm [PtBi_{6}}X{\rm _{8}}X\rm_{4/2}]$. Despite the high metal content and their polymeric character, the compounds are semi‐conducting since all valence electrons are localized in the electron precise clusters.
Kinetics and Mechanism of Formation and Acid–Catalyzed Decomposition of the [Co(NH3)4CO3]+ Complex Cation in Aqueous Solution
Authors: Jacewicz Dagmara , Chylewska Agnieszka , Dąbrowska Aleksandra , Chmurzyński Lech 
Published: November 2007

AbstractIt has been found that the kinetics of acid‐catalyzed hydrolysis of the [Co(NH3)4CO3]+ cation follows the rate law –d ln [complex]/d t = k1K[H+]/(1+K[H+]) (5 °C < T < 25 °C; 0.0543M < [HClO4] < 2.7M and I = 1.0M (NaClO4). The reaction course consists of a rapid pre‐equlibrium protonation followed by a rate determining ring opening process and the subsequent fast release of monodentate carbonato ligand. The changes of the absorbance for the acidic aqueous solution of the [Co(NH3)4CO3]+ complex ion proceeded at relevant wavelength in the UV‐Vis region and time course of these changes were analysed according to a programme “Glint” for the consecutive first – order reaction with two experimental rate constants kfast and kslow. Finally, the aquation mechanism has been proposed and the effect of ligand coordination mode (bidentate carbonato anion) on complex reactivity has been discussed.
Geochemical characteristics of mafic lavas from the Neotethyan ophiolites in western Turkey: implications for heterogeneous source contribution during variable stages of ocean crust generation
Authors: ALDANMAZ E. , YALINIZ M. K. , GÜCTEKIN A. , GÖNCÜOĞLU M. C. 
Published: November 2007

AbstractThe Late Triassic to Late Cretaceous age mafic lavas from the Neotethyan suture zone ophiolites in western Turkey exhibit a wide diversity of geochemical signatures, indicating derivation from extremely heterogeneous mantle sources. The rocks as a whole can be divided into three broad subdivisions based on their bulk-rock geochemical characteristics: (1) mid-ocean ridge basalts (MORB) that range in composition from light rare earth element (LREE)-depleted varieties (N-MORB; (La/Sm)N<1) through transitional MORB to LREE enriched types (E-MORB; (La/Sm)N>1); (2) the ocean island basalt (OIB)-type alkaline volcanic rocks with significant enrichment in LILE, HFSE and L-MREE, and a slight depletion in HREE, relative to normal mid-ocean ridge basalts (N-MORB); and (3) the supra-subduction zone (SSZ)-type tholeiites originated from arc mantle sources that are characterized by selective enrichments in fluid-soluble large ion lithophile elements (LILE) and LREE relative to the high field strength elements (HFSE). The formation of MORB tholeiites with variable enrichments and depletions in incompatible trace elements is probably related to the processes of crust generation along an oceanic spreading system, and the observed MORB–OIB associations can be modelled by heterogeneous source contribution and mixing of melts from chemically discrete sources from sub-lithospheric reservoirs. Evaluation of trace element systematics shows that the inferred heterogeneities within the mantle source regions are likely to have originated from continuous processes of formation and destruction of enriched mantle domains by long-term plate recycling, convective mixing and melt extraction. The origin of SSZ-type tholeiites with back-arc basin affinities, on the other hand, can be attributed to the later intra-oceanic subduction and plate convergence which led to the generation of supra-subduction-type oceanic crust as a consequence of imparting a certain extent of subduction component into the mantle melting region. Mixing of melts from a multiply depleted mantle source, which subsequently received variable re-enrichment with a subduction component, is suggested to explain the generation of supra-subduction-type oceanic crust. The geodynamic setting in which much of the SSZ-type ophiolitic extrusive rocks from western Turkey were generated can be described as an arc-basin system that is characterized by an oceanic lithosphere generation most probably associated with melting of mantle material along a supra-subduction-type spreading centre.