bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solvent‐Mediated Ion Exchange and Structural Transformations of Cluster‐Based Coordination Polymers
Authors: Zhang Jian‐Jun , Zhao Yue , Gamboa Sergio Aarón , Muñoz Miguel , Lachgar Abdessadek 
Published: May 2008

AbstractReactions between [Nb6Cl12(CN)6]4– and [Mn(salen)]+ in MeOH/H2O solvent mixture led to the formation of {[Mn(salen)(H2O)]2[(Mn(salen))2(Nb6Cl12(CN)6)]}·0.66 MeOH·5.33 H2O (1) which has a 2D anionic 4,4′‐network built of [Nb6Cl12(CN)6]4– and [Mn(salen)]+ nodes linked by CN ligands. The layers in 1 stack perfectly on top of each other and generate channels where dimeric complexes [Mn(salen)(H2O)]22+ are located. Unusual cation‐induced solvent‐mediated structural transformations have been observed when 1 was exposed to solutions of different cations. In contact with (Me4N)Cl in MeOH, 1 is transformed to the 2D framework of the previously reported compound [Me4N]2[(Mn(salen))2(Nb6Cl12(CN)6)] (2). In the presence of (Et3BzN)+, 1 is transformed into a mixture of [Et3BzN]2[(Mn(salen)(MeOH))2(Nb6Cl12(CN)6)]·4 MeOH (3) and [Et3BzN]2[(Mn(salen))2 (Nb6Cl12(CN)6)]·3 H2O (4) which are formed as crystals suitable for single‐crystal X‐ray diffraction. Compound 3 consists of heterotrimeric supramolecular anions built of [Nb6Cl12(CN)6]4– linked to two [Mn(salen)(H2O)]+ through two CN ligands located in axial positions, while 4 features 2D anionic 4,4′‐net with the same connectivity as that observed for 1 and 2 but different layer stacking and interlayer spacing. In contact with methanolic solution of (Et4N)+, 1 is converted to [Et4N]2[(Mn(salen)(H2O))2(Nb6Cl12(CN)6)]·6 H2O (5) which is built of heterotrimeric structural motif similar to those found in 3. In the presence of M+ [M+ = Li+, Na+, K+, (Bu4N)+, or (PPh4)+], the 2D framework of 1 is transformed to heteropentamers built of [Nb6Cl12(CN)6]4– linked to four [Mn(salen)(MeOH)]+: [(Mn(salen)(MeOH))4(Nb6Cl12(CN)6)]·4 MeOH (6). The mechanism for these unusual solvent‐mediated phase‐to‐phase transformation is discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Allylic Amination and Aziridination of Olefins by Aryl Azides Catalyzed by CoII(tpp): A Synthetic and Mechanistic Study
Authors: Caselli Alessandro , Gallo Emma , Fantauzzi Simone , Morlacchi Simona , Ragaini Fabio , Cenini Sergio 
Published: May 2008

AbstractCoII(tpp) catalyzes the reaction of aromatic azides (ArN3) with nonactivated olefins to yield allylic amines or aziridines in moderate‐to‐good yields. The chemoselectivity of the catalytic reaction is particularly high. Depending on the substrate employed, allylic amines or aziridines can be obtained. The reaction mechanism was investigated, and the reaction proceeds through reversible coordination of the aryl azide to the CoII–porphyrin complex. The often postulated “nitrene” complex is not an intermediate in this reaction. The kinetics for the allylic amination is first order in azide, Co(tpp), and olefin. For the aziridination, the kinetics is again first order in azide and catalyst, but we observed a first‐order dependence of the rate on α‐methylstyrene only up to an olefin concentration of 6.9 M. An inhibiting role of the competitively formed 1‐(4‐nitrophenyl)‐5‐methyl‐5‐phenyl‐1,2,3‐triazoline was identified. The triazoline was shown to reversibly coordinate to Co(tpp), which blocks the free coordination site necessary for the catalytic reaction to proceed, and is it responsible for the catalyst deactivation in the aziridination reaction of α‐methylstyrene by 4‐nitrophenyl azide. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
An Atropo‐Stereogenic Diphosphane Ligand with a Proximal Cationic Charge: Specific Catalytic Properties of a Palladium Complex Thereof
Authors: Debono Nathalie , Canac Yves , Duhayon Carine , Chauvin Remi 
Published: May 2008

AbstractA class of cationic diphosphane ligands combining phosphane and amidiniophosphane moieties is illustrated on the N‐methyl,N‐naphthylbenzimidazolium framework. The palladium(II) complex thereof is described and compared to the corresponding complex of the analogous neutral diphosphane. Contrary to first‐level expectations, the N2C–P and N2CP–Pd bonds in the cationic diphosphane complex are not longer than those occurring in its neutral counterpart. In the cationic ligand, the proximal positive charge is indeed conjugated to one phosphanyl group, and the coordination scheme is tentatively interpreted by resonance of the phosphane→metal dative bond (+N2C–P:→[Pd]) with a carbene→phosphenium dative bond (N2C:→[+P:→Pd]). Despite this peculiar structural feature, the electronic σ donation (vs. π acceptation) towards the palladium centre remains lowered in the cationic ligand. This specific property can be a priori valuable in a catalytic process where oxidative addition is not the limiting step. It is indeed shown that although the neutral complex is more active in Suzuki coupling reactions, the cationic complex is more active in Sonogashira‐type coupling reactions involving predissociated halide substrates, namely an acyl chloride. These likely atropo‐chiral ligands deserve to be resolved for application in asymmetric catalysis.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Crystal Structures of Ag2ZrF6·8NH3 and Ag2HfF6·8NH3 and Their Synthesis by the “Reactive Fluoride Route” in Liquid Ammonia
Authors: Meng Weizhe , Kraus Florian 
Published: May 2008

AbstractStarting from the ternary transition‐metal fluorides Ag3M2F14 (M = Zr, Hf) and dry liquid ammonia, [Ag(NH3)4(μ‐NH3)Ag(NH3)3]ZrF6 (1) and [Ag(NH3)4(μ‐NH3)Ag(NH3)3]HfF6 (2) have been prepared as colorless single crystals crystallizing isotypically in the space group Pnma‐D2h16 (No. 62). The compounds feature weak Ag···Ag interactions known as argentophilicity, which is yet unknown in fluorides. It is also shown that ionic silver(II) fluorides are suitable starting materials for fluorine chemistry in liquid ammonia and are easily reduced to AgI by oxidizing ammonia. This driving force bypasses the generally high lattice energy of ionic fluorides, so that they can be dissolved easily. We would like to introduce the term “reactive fluoride route” for this method of dissolving reactive ionic fluorides in liquid ammonia. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A Rare Thermally Induced Single Crystal to Single Crystal Transformation from a 2D Chiral Coordination Polymer to a 3D Chiral Coordination Polymer
Authors: Zhu Ping , Gu Wen , Zhang Li‐Zhi , Liu Xin , Tian Jin‐Lei , Yan Shi‐Ping 
Published: May 2008

AbstractA rare single‐crystal to single crystal (SCSC) transformation assisted by hydrogen bonding was induced thermally. A2D homochiral coordination polymer {[Ni2(L‐tar)2(H2O)2](H2O)3}∞ was irreversibly converted into a 3D homochiral coordination polymer, and the structure was confirmed by X‐ray crystallography and XRD. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Lanthanide‐Hinged Calixarene Bicapsules: Discrete Hexanuclear LnIII/Phenanthroline/p‐Sulfonatocalix[4]arene Oligomers (Ln = Gd, Tb)
Authors: Liao Wuping , Bi Yanfeng , Gao Song , Li Deqian , Zhang Hongjie , Dronskowski Richard 
Published: May 2008

AbstractThe dumbbell‐like calixarene bicapsule in two novel LnIII–C4AS compounds was found to be a hexanuclear LnIII/phenanthroline/p‐sulfonatocalix[4]arene oligomer. The magnetic and luminescent properties of these compounds were examined. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
An Iron(II) Spin‐Transition Compound with Thiol Anchoring Groups (Eur. J. Inorg. Chem. 17/2008)
Authors: Chandrasekar Rajadurai , Schramm Frank , Fuhr Olaf , Ruben Mario 
Published: May 2008

AbstractThe cover picture shows
the solid‐state structure and magnetic susceptibility data of an iron(II) spin‐transition complex, which was designed, synthesized and characterized in the group of Mario Ruben at the Institute of Nanotechnology in Karlsruhe. The complex, which undergoes a near‐room‐temperature transition from a closed‐shell spin singlet to an open‐shell high‐spin state, holds promise for the controlled manipulation and readout of the magnetic states of single molecules. In order to integrate and to implement such switchable spin‐transition units into electronic devices, the molecule bears protected thiol linkers, which allows its attachment to gold electrodes (bottom). Details are discussed in the Short Communication on p. 2649 ff.
The Australian Research Quality Framework: A live experiment in capturing the social, economic, environmental, and cultural returns of publicly funded research
Authors: Donovan Claire 
Published: May 2008

AbstractThe author regards development of Australia's ill‐fated Research Quality Framework (RQF) as a “live experiment” in determining the most appropriate approach to evaluating the extra‐academic returns, or “impact,” of a nation's publicly funded research. The RQF was at the forefront of an international movement toward richer qualitative, contextual approaches that aimed to gauge the wider economic, social, environmental, and cultural benefits of research. Its construction and implementation sent mixed messages and created confusion about what impact is, and how it is best measured, to the extent that this bold live experiment did not come to fruition. © Wiley Periodicals, Inc.
The logic of research evaluation
Authors: Scriven Michael , Coryn Chris L. S. 
Published: May 2008

AbstractThe authors offer suggestions about logical distinctions often overlooked in the evaluation of research, beginning with a strong plea not to treat technology as applied science, and especially not to treat research in technology as important only if it makes a contribution to scientific knowledge. They argue that the frameworks illustrated in this issue for the evaluation of technology centers and their research are superior to those used for evaluating science centers. Ways to improve the evaluation of research are suggested. © Wiley Periodicals, Inc.
Direction‐of‐change forecasting using a volatility‐based recurrent neural network
Authors: Bekiros S. D. , Georgoutsos D. A. 
Published: May 2008

AbstractThis paper investigates the profitability of a trading strategy, based on recurrent neural networks, that attempts to predict the direction‐of‐change of the market in the case of the NASDAQ composite index. The sample extends over the period 8 February 1971 to 7 April 1998, while the sub‐period 8 April 1998 to 5 February 2002 has been reserved for out‐of‐sample testing purposes. We demonstrate that the incorporation in the trading rule of estimates of the conditional volatility changes strongly enhances its profitability, after the inclusion of transaction costs, during bear market periods. This improvement is being measured with respect to a nested model that does not include the volatility variable as well as to a buy‐and‐hold strategy. We suggest that our findings can be justified by invoking either the ‘volatility feedback’ theory or the existence of portfolio insurance schemes in the equity markets. Our results are also consistent with the view that volatility dependence produces sign dependence. Copyright © 2008 John Wiley & Sons, Ltd.
Evaluating sulfur dynamics during storm events for three watersheds in the northeastern USA: a combined hydrological, chemical and isotopic approach
Authors: Mitchell Myron J. , Bailey Scott W. , Shanley James B. , Mayer Bernhard 
Published: May 2008

AbstractConcerns related to climate change have resulted in an increasing interest in the importance of hydrological events such as droughts in affecting biogeochemical responses of watersheds. The effects of an unusually dry summer in 2002 had a marked impact on the biogeochemistry of three watersheds in the north‐eastern USA. Chemical, isotopic and hydrological responses with particular emphasis on S dynamics were evaluated for Archer Creek (New York), Sleepers River (Vermont) and Cone Pond (New Hampshire) watersheds. From 1 August to 14 September 2002, all three watersheds had very low precipitation (48 to 69 mm) resulting in either very low or no discharge (mean 0·015, 0·15 and 0·000 mm day−1 for Archer Creek, Sleepers River and Cone Pond, respectively). From 15 September to 31 October 2002, there was a substantial increase in precipitation totals (212, 246 and 198 mm, respectively) with increased discharge. Archer Creek was characterized by a large range of SO42− concentrations (152 to 389 µeq L−1, mean = 273 µeq L−1) and also exhibited the greatest range in δ34S values of SO42− (−1·4 to 8·8 ‰ ). Sleepers River's SO42− concentrations ranged from 136 to 243 µeq L−1 (mean = 167 µeq L−1) and δ34S values of SO42− ranged from 4·0 to 9·0 ‰ . Cone Pond's SO42− concentrations (126–187 µeq L−1, mean = 154 µeq L−1) and δ34S values (2·4 to 4·3 ‰ ) had the smallest ranges of the three watersheds. The range and mean of δ18O‐SO42− values for Archer Creek and Cone Pond were similar (3·0 to 8·9 ‰ , mean = 4·5 ‰ ; 3·9 to 6·3 ‰ , mean = 4·9 ‰ ; respectively) while δ18O‐SO42− values for Sleepers River covered a larger range with a lower mean (1·2 to 10·0 ‰ , mean = 2·5). The difference in Sleepers River chemical and isotopic responses was attributed to weathering reactions contributing SO42−. For Archer Creek wetland areas containing previously reduced S compounds that were reoxidized to SO42− probably provided a substantial source of S. Cone Pond had limited internal S sources and less chemical or isotopic response to storms. Differences among the three watersheds in S biogeochemical responses during these storm events were attributed to differences in S mineral weathering contributions, hydrological pathways and landscape features. Further evaluations of differences and similarities in biogeochemical and hydrological responses among watersheds are needed to predict the impacts of climate change. Copyright © 2008 John Wiley & Sons, Ltd.
Lateral flow thresholds for aspen forested hillslopes on the Western Boreal Plain, Alberta, Canada
Authors: Redding T. E. , Devito K. J. 
Published: May 2008

AbstractTo predict the long‐term sustainability of water resources on the Boreal Plain region of northern Alberta, it is critical to understand when hillslopes generate runoff and connect with surface waters. The sub‐humid climate (P ≤ ET) and deep glacial sediments of this region result in large available soil storage capacity relative to moisture surpluses or deficits, leading to threshold‐dependent rainfall‐runoff relationships. Rainfall simulation experiments were conducted using large magnitude and high intensity applications to examine the thresholds in precipitation and soil moisture that are necessary to generate lateral flow from hillslope runoff plots representative of Luvisolic soils and an aspen canopy. Two adjacent plots (areas of 2·95 and 3·4 m2) of contrasting antecedent moisture conditions were examined; one had tree root uptake excluded for two months to increase soil moisture content, while the second plot allowed tree uptake over the growing season resulting in drier soils. Vertical flow as drainage and soil moisture storage dominated the water balances of both plots. Greater lateral flow occurred from the plot with higher antecedent moisture content. Results indicate that a minimum of 15–20 mm of rainfall is required to generate lateral flow, and only after the soils have been wetted to a depth of 0·75 m (C‐horizon). The depth and intensity of rainfall events that generated runoff > 1 mm have return periods of 25 years or greater and, when combined with the need for wet antecendent conditions, indicate that lateral flow generation on these hillslopes will occur infrequently. Copyright © 2008 John Wiley & Sons, Ltd.
Upregulation of miR‐23a∼27a∼24 decreases transforming growth factor‐beta‐induced tumor‐suppressive activities in human hepatocellular carcinoma cells
Authors: Huang Shenglin , He Xianghuo , Ding Jie , Liang Linhui , Zhao Yingjun , Zhang Zhenfeng , Yao Xiao , Pan Zhimei , Zhang Pingping , Li Jinjun , Wan Dafang , Gu Jianren 
Published: May 2008

AbstractTransforming growth factor‐beta (TGF‐beta) plays a dual and complex role in human cancer. In this report, we observe a specific set of MicroRNAs (miRNAs) changed in response to TGF‐beta in human hepatocellular carcinoma (HCC) cells by miRNA microarray screening. A cluster of miRNA, miR‐23a∼27a∼24, is induced in an early stage by TGF‐beta in Huh‐7 cells. Knockdown of Smad4, Smad2 or Smad3 expression by RNA interference can attenuate the response of miR‐23a∼27a∼24 to TGF‐beta addition, indicating that this induction is dependent on Smad pathway. We also explore that miR‐23a∼27a∼24 can function as an antiapoptotic and proliferation‐promoting factor in liver cancer cells. In addition, expression of this miRNA cluster is found to be remarkably upregulated in HCC tissues versus normal liver tissues. These findings suggest a novel, alternative mechanism through which TGF‐beta could induce specific miRNA expression to escape from tumor‐suppressive response in HCC cells. © 2008 Wiley‐Liss, Inc.
Kaempferol: A new immunosuppressant of calcineurin
Authors: Wang Hu , Zhou Chun‐Lei , Lei Hong , Zhang Song‐Dong , Zheng Jianquan , Wei Qun 
Published: May 2008

AbstractCalcineurin (CN), the Ca2+/calmodulin (CaM)‐dependant protein phosphatase, is the target for immunosuppressive drugs cyclosporine A (CsA) and FK506. These immunosuppressants can inhibit CN activity after binding with respective immunophilins. Based on the model of screening by using p‐nitrophenyl phosphate as a substrate for preliminary screening and 32P‐labeled 19‐residue phosphopeptide as a specific substrate for final determination, we found Kaempferol, a natural flavonol, could inhibit CN activity in purified enzyme and Jurkat T‐cells. Unlike CsA and FK506, CN inhibition by kaempferol is independent of matchmaker protein and the inhibitory manner is noncompetitive. Through investigation of inhibitions for CNA and a series of its truncated mutants, we suggested that Kaempferol could directly act on the catalytic domain. Data also indicated that the CN inhibition by kaempferol could be enhanced when the enzyme was activated in the presence of CaM and CNB. CNB is necessary for mediating inhibition of enzyme by kaempferol. The result of RT‐PCR also indicated that kaempferol had an inhibitory activity against IL‐2 gene expression in activated Jurkat cells. All data suggested that kaempferol could be a new immunosuppressant of CN. © 2008 IUBMB IUBMB Life, 60(8): 549–554, 2008
Proteasome activation as a novel antiaging strategy
Authors: Chondrogianni Niki , Gonos Efstathios S. 
Published: May 2008

AbstractHomeostasis is a key feature of cellular lifespan. Maintenance of cellular homeostasis influences the rate of aging and is determined by several factors, including efficient proteolysis of damaged proteins. Protein degradation is predominately catalyzed by the proteasome. Specifically, the proteasome is responsible for cell clearance of abnormal, denatured or in general damaged proteins as well as for the regulated degradation of short‐lived proteins. As proteasome has an impaired function during aging, emphasis has been given recently in identifying ways of its activation. A number of studies have shown that the proteasome can be activated by genetic manipulations as well as by factors that affect its conformation and stability. Importantly the developed proteasome activated cell lines exhibit an extended lifespan. This review article discusses in details the various factors that are involved in proteasome biosynthesis and assembly and how they contribute to its activation. Finally as few natural compounds have been identified having proteasome activation properties, we discuss the advantages of this novel antiaging strategy. © 2008 IUBMB IUBMB Life, 60(10): 651–655, 2008
A DNA transporter based on mesoporous silica nanospheres mediated with polycation poly(allylamine hydrochloride) coating on mesopore surface
Authors: Qin Fei , Zhou Yuchuan , Shi Jianlin , Zhang Yonglian 
Published: May 2008

AbstractMesoporous silica nanospheres (MPNSs) were synthesized by the sol–gel method and were investigated by X‐ray diffraction, nitrogen sorption, and transmission electron microscopy. The analyses showed that the MPNSs were highly dispersed, with a diameter range of 50–250 nm. Further, the polycation poly(allylamine hydrochloride) was coated on silica MPNSs to form a positively charged surface and to facilitate the loading of DNA molecules. The composite was successfully used as a intercellular carrier of DNA molecules, and this was confirmed by agarose gel electrophoresis and confocal laser scanning microscopy. Evidently, this composite has potential to be used as a carrier for a DNA delivery system. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Physico/chemical characterization and in vivo evaluation of nanothickness bioceramic depositions on alumina‐blasted/acid‐etched Ti‐6Al‐4V implant surfaces
Authors: Coelho Paulo G. , Lemons Jack E. 
Published: May 2008

AbstractThe objective of this study was to physico/chemically characterize and evaluate the in vivo performance of two nanothickness ion beam assisted depositions (IBAD) of bioceramic coatings on implants in a beagle model. Alumina‐blasted/acid‐etched (AB/AE) Ti‐6Al‐4V implants were subjected to two different IBAD depositions (IBAD I and IBAD II), which were physico/chemically characterized by SEM, EDS, XPS, XPS + ion‐beam milling (depth profiling), XRD, AFM, and ToF‐SIMS. A beagle dog tibia model was utilized for histomorphometric and biomechanical (torque) comparison between AB/AE, IBAD I, IBAD II, and plasma‐sprayed hydroxyapatite (PSHA) coated implants that remained in vivo for 3 and 5 weeks. The coatings were characterized as amorphous Ca‐P with high Ca/P stoichiometries with thicknesses of an order of magnitude difference (IBAD I = 30–50 nm and IBAD II = 300–500 nm). The histomorphometric and biomechanical testing results showed that the 300–500 nm thickness deposition (IBAD II) and PSHA positively modulated bone healing at early implantation times. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Impaction allografting—The effect of impaction force and alternative compaction methods on the mechanical characteristics of the graft
Authors: Albert Carolyne , Masri Bassam , Duncan Clive , Oxland Thomas , Fernlund Göran 
Published: May 2008

AbstractRevision total hip replacement with impaction allografting has an attractive potential for restoring bone stock, however, fractures and implant migration remain problematic. Postoperative graft deformation is believed to contribute to migration. Under compressive loading, the fluid in the graft takes up the load initially through fluid pressure that dissipates over time. Given the short duration of an impaction, we proposed two novel graft compaction techniques that allow more time for fluid flow: holding a compression force constant for 90 s (creep technique), and cycles of compressing the graft to a given force and then holding the displacement constant (cyclic relaxation technique). This study examined the effect of the impaction force on the density and mechanical characteristics of the graft, and explored the potential benefit of the proposed alternative compaction techniques. Increasing the impaction force from “low” to “high” increased graft density by 41%, and this translated to stiffness and shear strength increases of 93 and 164%, respectively. The creep technique improved the stiffness and shear strength by 14 and 16%, respectively, when compared with impaction, while the cyclic relaxation technique did not improve the mechanical properties. Although the creep technique could potentially provide a lower risk of intraoperative fracture over the use of larger impaction forces, any clinical benefit of the creep technique warrants further investigation. Our results point to the importance of maximizing impaction forces in impaction allografting surgery. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008