bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism‐Guided Development of VO(salen)X Complexes as Catalysts for the Asymmetric Synthesis of Cyanohydrin Trimethylsilyl Ethers
Authors: Belokon Yuri N. , Clegg William , Harrington Ross W. , Maleev Victor I. , North Michael , Pujol Marta Omedes , Usanov Dmitry L. , Young Carl 
Published: January 2009

AbstractCatalyze this! Detailed study of the mechanism of asymmetric cyanohydrin synthesis catalyzed by VO(salen)X complexes (see figure) led to the development of VO(salen)NCS, as the most active vanadium‐based catalyst yet developed for this reaction.magnified imageThe mechanism by which oxovanadium(V)(salen) complexes1 VO(salen)X catalyze the asymmetric addition of trimethylsilyl cyanide to benzaldehyde has been studied. The reaction kinetics indicated that the structure of the counterion (X) had a significant influence on the rate, but not on the enantioselectivity of the reaction. The less coordinating the counterion, the lower the catalytic activity; a trend that was confirmed by a Hammett analysis. Variable temperature kinetics allowed the enthalpies and entropies of activation to be determined for some catalysts, and showed that, for others, the overall reaction order changes from second order to zero order as the temperature is reduced. The order with respect to the catalyst was determined for nine of the VO(salen)X complexes and showed that the less active catalysts were active predominantly as mononuclear species whilst the more active catalysts were active predominantly as dinuclear species. Mass spectrometry confirmed the formation of dinuclear species in situ from all of the VO(salen)X complexes and indicated that the dinuclear complexes contained one vanadium(V) and one vanadium(IV) ion. The latter conclusion was supported by cyclic voltammetry of the complexes, by fluorescence measurements and by the fact that catalyst deactivation occurs when reactions are carried out under an inert atmosphere. Based on this evidence, it has been deduced that the catalysis involves two catalytic cycles: one for catalysis by mononuclear VO(salen)X species and the other for catalysis by dinuclear species. The catalytic cycle involving dinuclear species involves activation of both the cyanide and aldehyde, whereas the catalytic cycle involving mononuclear species activates only the aldehyde, thus explaining the higher catalytic activity observed for catalysts which are predominantly active as dinuclear complexes. Based on these mechanistic results, two new VO(salen)X complexes (X=F and NCS) were predicted to form highly active catalysts for asymmetric cyanohydrin synthesis. VO(salen)NCS was indeed found to be the most active catalyst of this type and catalyzed the asymmetric addition of trimethylsilyl cyanide to thirteen aldehydes. In each case, high yields and enantioselectivities were obtained after a reaction time of two hours at room temperature using just 0.1 mol % of the catalyst.
Size Effect of 3D Aggregates Assembled from Silver Nanoparticles on Surface‐Enhanced Raman Scattering
Authors: Kahraman Mehmet , Aydin Ömer , Çulha Mustafa 
Published: January 2009

AbstractSize matters: Nanometer‐sized gaps in aggregates of silver nanoparticles are generated by covering the nanoparticle surface with a bilayer of cetyltrimethylammonium bromide. The nanometer‐ to micrometer‐sized wells are lithographically generated on polydimethylsiloxane surfaces. The wells filled with the modified nanoparticles (see picture) and the effect of the aggregate size on SERS enhancement are investigated.magnified imageThe size influence of 3D silver nanoparticle aggregates on surface‐enhanced Raman scattering (SERS) is investigated. Micrometer‐ and nanometer‐sized wells prepared on a polydimethylsiloxane (PDMS) surfaces are filled with cetyltrimethylammonium bromide (CTAB)‐coated silver nanoparticles. A concentration of CTAB around its critical micelle concentration is used not only to form a bilayerlike structure around the nanoparticles and thus generate nanometer‐sized gaps in the aggregates, but also to improve the compatibility of the surface charge properties of the silver nanoparticles with the surface of PDMS and thus successfully fill the wells by assembly of silver nanoparticles into 3D structures. A resonance‐free enhancement factor of 107 can be easily achieved on larger aggregates, and the enhancement factor increases with decreasing size of the 3D aggregates, which is contrary to reported studies on conventional silver clusters. We find that the number of silver nanoparticles in the 3D aggregate should be less than 200–300 for optimal SERS performance.
Proposal of switching power amplifier using small‐capacity linear amplifier and LC filter
Authors: Kamada Jo , Funato Hirohito , Ogasawara Satoshi 
Published: January 2009

AbstractHigh efficiency and low noise in output voltage and current are required in audio‐video equipment, medical apparatus, and many other applications. This paper proposes a power amplifier in which a PWM inverter is used as the main circuit. In the proposed power amplifier, a hybrid filter consisting of a simple conventional type LC filter and a small‐capacity linear amplifier is connected to the inverter output. The linear amplifier is inserted in series to the filter capacitor to improve the filtering effect of the LC filter. Switching ripples and LC resonances are considerably suppressed by controlling the amplifier using the proposed method, thus implementing a low‐distortion switching power amplifier. The effects of the proposal circuit are verified by simulation and experiments. As a result, the proposed circuit achieves low noise about THD=0.68% in simulation and THD=1.5% in experiment. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(10): 1–10, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10161
Cycle analysis of low and high H2 utilization SOFCs/gas turbine combined cycle for CO2 recovery
Authors: Taniuchi Takuya , Sunakawa Daisuke , Nagahama Mitsuyuki , Araki Takuto , Onda Kazuo , Kato Toru 
Published: January 2009

AbstractGlobal warming is mainly caused by CO2 emission from thermal power plants, which burn fossil fuel with air. One of the countermeasure technologies to prevent global warming is CO2 recovery from combustion flue gas and the sequestration of CO2 underground or in the ocean. SOFC and other fuel cells can produce high‐concentration CO2, because the reformed fuel gas reacts with oxygen electrochemically without being mixed with air, or diluted by N2. Thus, we propose to operate the multistage SOFCs under high utilization of reformed fuel for obtaining high‐concentration CO2. In this report, we have estimated the multistage SOFCs' performance considering H2 diffusion and the combined cycle efficiency of multistage SOFC/gas turbine/CO2 recovery power plant. The power generation efficiency of our CO2 recovery combined cycle is 68.5% and the efficiency of conventional SOFC/GT cycle is 57.8% including the CO2 recovery amine process. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(10): 38–45, 2008; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/ecj.10165
Analysis and measurement of consumer electric power generation at the time of grid‐interconnection of clustered photovoltaic power generation systems
Authors: Matsuda Katsuhiro , Wada Masaru , Furukawa Toshiyuki , Watanabe Masahiro , Kobayashi Hiromu 
Published: January 2009

AbstractSince photovoltaic generators (PV) have been mainly introduced in residential areas, it is necessary to consider the consequences of setting up large numbers of PVs locally. In such a situation, it will be difficult to manage the voltage in distribution lines, because the reverse power supplied from the PV raises the voltage of the power lines. In this study, a large PV system was connected to a distribution system, and for every inverter the authors used simulations to verify the appraisal of systematic voltage and the electric power generation. As a result, the authors verified that power factor control is more effective than output control. In addition, the authors verified that with each user the power generation becomes more unequal. In the future, when a large PV system is connected to a distribution system, the problem of unsatisfactory equalization of demand for home appliance usage may arise. A method for determining the set value for the inverter for each user was proposed in order to solve this problem, and the effectiveness of the proposed technique was verified through simulations. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(10): 46– 58, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10166
Formation of HoIII Trinuclear Clusters and GdIII Monodimensional Polymers Induced by ortho and para Regioisomers of Pyridyl‐Functionalised β‐Diketones: Synthesis, Structure, and Magnetic Properties
Authors: Andrews Philip C. , Deacon Glen B. , Frank René , Fraser Benjamin H. , Junk Peter C. , MacLellan Jonathan G. , Massi Massimiliano , Moubaraki Boujemaa , Murray Keith S. , Silberstein Morry 
Published: January 2009

AbstractReaction of GdCl3(H2O)6 and 1,3‐bis(pyridin‐4‐yl)propane‐1,3‐dione in methanol with an excess of triethylamine produced a monodimensional polymeric chain [Gd(p‐dppd)3(H2O)]∞, whereas treatment of HoCl3(H2O)6 with 1,3‐bis(pyridin‐2‐yl)propane‐1,3‐dione yielded a trinuclear cluster [Ho3(o‐dppd)3(μ3‐OH)2(H2O)4Cl2]Cl2. The compounds were characterised by elemental analysis, IR spectroscopy and magnetism, and their structures were investigated by X‐ray crystallography. The 8.20‐μB magnetic‐moment value of the polymeric [Gd(p‐dppd)3(H2O)]∞, between 300 and 20 K, and the magnetisation isotherms (2–20 K; fields 0–5 T), are in agreement with essentially uncoupled single‐ion Gd3+ f7 centres, a small decrease in μeff below 20 K being indicative of zero‐field splitting. A temperature‐dependent dc‐susceptibility and magnetisation investigation of the trinuclear (triangular) [Ho3(o‐dppd)3(μ3‐OH)2(H2O)4Cl2]Cl2 revealed that spin‐orbit and ligand‐field effects on the Ho3+ centres, leading to thermal depopulation of Zeeman levels and consequent decreases in μeff values with decreasing temperature, are occurring rather than weak intra‐cluster antiferromagnetic coupling. Frequency‐ and temperature‐dependent ac‐susceptibility studies on this homometallic Ho3+ cluster did not show clear evidence for slow magnetisation reversal, characteristic of single‐molecule magnetism (SMM), and this contrasts with such behaviour recently reported, elsewhere, for a Dy3+ triangle having the same core structure but with different chelating {O,O} ligands.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
An Unsymmetrical Mixed‐Valent Divanadium(IV/V) Complex
Authors: Sarkar Anindita , Pal Samudranil 
Published: January 2009

AbstractIn acetonitrile medium, reaction of bisacetylacetonatooxovanadium(IV) {[VO(acac)2]} and acetylhydrazine (CH3CONHNH2) in a 2:1 molar ratio provides a novel, unsymmetrical, chiral, mixed‐valent, triply bridged, dinuclear vanadium(IV/V) complex having the formula [(Hdmpz)OV(μ‐acac)(μ‐O)(μ‐O2CCH3)VO(acac)] (Hdmpz = 3,5‐dimethylpyrazole). The molecular structure of the complex was confirmed by X‐ray crystallography. It crystallizes in the chiral space group P212121 indicating a spontaneous resolution in the crystal. The complex is one‐electron paramagnetic and redox active. It displays VVVIV to VVVV oxidation and VVVIV to VIVVIV reduction responses. The crystal structure and EPR measurements revealed the trapped‐valent character of the complex in the solid state as well as in the solution phase. Circular dichroism spectroscopic measurements with a powdered sample revealed that the bulk material is not racemic. In solution, the existence of both enantiomers of the complex is demonstrated by the Pfeiffer effect with the use of L‐ and D‐arabinose as environment substances.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Synthesis and Reactivity of Ru(NHC)(dppp)(CO)H2 and Ru(NHC)(dppp)(CO)HF Complexes: C–H and C–F Activation
Authors: Reade Steven P. , Acton Aaron L. , Mahon Mary F. , Martin Thomas A. , Whittlesey Michael K. 
Published: January 2009

AbstractThe hydrido fluorido ruthenium(II) complex [Ru(PPh3)(dppp)(CO)HF] [1, dppp = 1,4‐bis(diphenylphosphanyl)propane], which forms upon reaction of [Ru(PPh3)3(CO)HF] with dppp, reacts with IMes [1,3‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene] to give the expected carbene‐containing hydrido fluorido complex [Ru(IMes)(dppp)(CO)HF] (2), as well as the C–H activated species [Ru(IMes)′(dppp)(CO)H] (3). The formation of the latter product results from the reaction of 2 with a base (IMes or Et3N). Displacement of PPh3 from [Ru(PPh3)(dppp)(CO)H2] by ICy (1,3‐dicyclohexylimidazol‐2‐ylidene) yields [Ru(ICy)(dppp)(CO)H2] (7), which upon reaction with Et3N·3HF, gives [Ru(ICy)(dppp)(CO)HF] (8). Thermolysis of 7 with C6F6 at elevated temperature generates 8 and [Ru(ICy)(dppp)(CO)(C6F5)H] (9). The related fluoroaryl complexes [Ru(ICy)(dppp)(CO)(C6F4CF3)H] (10) and [Ru(ICy)(dppp)(CO)(C5F4N)H] (11) are formed upon the room temperature C–F activation of C6F5CF3 and C5F5N by 7, but also by C–H activation of the partially fluorinated substrates p‐C6F4HCF3 and p‐C5F4HN.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
A portable capillary electropherograph equipped with a cross‐sampler and a contactless‐conductivity detector for the detection of the degradation products of chemical warfare agents in soil extracts
Authors: Seiman Andrus , Martin Jaanus , Vaher Merike , Kaljurand Mihkel 
Published: January 2009

AbstractA fully portable CE device equipped with a capacitively coupled contactless‐conductivity detector and a cross‐injection device is put to the test in laboratory conditions. The portable device is capable of working on batteries for at least 4 h. After that, its performance is strongly affected by the drop in the high‐voltage output and analysis may be interrupted if its length exceeds a reasonable time. The concentration of the BGE affects both ionic strength and conductivity. Choosing an optimal concentration of BGE is therefore about finding a good compromise between selectivity and sensitivity. All experiments were performed using a mixture of histidine and MES with a concentration of 15 mM as BGE. The performance of the cross‐injection device is optimized by the use of internal standards. Satisfactory reproducibility is gained as the RSD of peak areas is reduced to 8% or less. LODs for different phosphonic acids are in the range of 2.5–9.7 μM. For the analysis of adsorption of phosphonic acids in sand and loamy soil samples, calibration curves are constructed. Linearity in a measured concentration range of 10–100 μM is excellent, as the squares of correlation constants are ∼1. The concentration analysis of phosphonic acids in soil extracts demonstrates that their adsorption curves in sand and loamy soil follow different adsorption isotherms.
Characterization of the 7q21‐q22 amplicon identifies ARPC1A, a subunit of the Arp2/3 complex, as a regulator of cell migration and invasion in pancreatic cancer
Authors: Laurila Eeva , Savinainen Kimmo , Kuuselo Riina , Karhu Ritva , Kallioniemi Anne 
Published: January 2009

AbstractPancreatic cancer is a highly aggressive malignancy and one of the leading causes of cancer deaths, mainly due to the lack of methods for early diagnosis and the lack of effective therapies. Recent CGH microarray studies have revealed several regions that are recurrently amplified in pancreatic cancer; these are thus likely to contain genes that contribute to cancer pathogenesis and thereby could serve as novel diagnostic and therapeutic targets. Here, we performed a detailed characterization of the 7q21‐q22 amplicon in pancreatic cancer to identify putative amplification target genes. Fluorescence in situ hybridization analyses in 16 pancreatic cancer cell lines and 29 primary pancreatic tumors revealed an increased copy number in ∼25% of cases in both sample groups, and the cell line data also allowed us to identify a 0.77 Mb amplicon core region containing ten transcripts. Gene expression analyses by qRT‐PCR highlighted the ARPC1A gene as having the statistically most significant correlation between amplification and elevated expression (P = 0.004). Silencing of ARPC1A by RNA interference in AsPC‐1 cells having high level amplification and expression resulted in a slight decrease in cell proliferation, but a massive reduction in cell migration and invasion. ARPC1A codes for the p41 subunit of the Arp2/3 protein complex, which is a key player in actin polymerization and thus regulates cell mobility. Taken together, our data implicate ARPC1A as a novel target for the 7q21‐q22 amplification and a regulator of cell migration and invasion in pancreatic cancer, thus making it an interesting target for antimetastasis therapy. © 2009 Wiley‐Liss, Inc.
Chronic medical problems and distressful thoughts of suicide in primary care patients: mitigating role of happiness
Authors: Hirsch Jameson K. , Duberstein Paul R. , Unützer Jürgen 
Published: January 2009

AbstractObjectiveChronic medical problems might amplify suicide risk in later life. Feelings of happiness may reduce this risk. We tested the hypothesis that happiness attenuates the association between number of self‐reported chronic diseases and suicidal distress.MethodsA sample of 1,801 depressed, primary care patients, 60 years of age or older, entering a clinical trial, were assessed for the presence of positive emotion, suicidal distress and self‐reported chronic medical problems.ResultsChronic medical problems are associated with suicide ideation and, as hypothesized, happiness attenuates the relationship between self‐reported diseases and suicidal distress.ConclusionsDecreased risk for distressing thoughts of suicide in the context of medical illness is predicted by the presence of positive emotions. Our results suggest that treatments designed to help older primary care patients identify sources of joy and enhance happiness might decrease suicide risk. Copyright © 2009 John Wiley & Sons, Ltd.
Using a fluctuating tracer to estimate hyporheic exchange in restored and unrestored reaches of the Truckee River, Nevada, USA
Authors: Knust Andrew E. , Warwick John J. 
Published: January 2009

AbstractThe goal of this research was to compare hyporheic activity in recently restored and adjacent un‐restored reaches of the Truckee River downstream from the Reno/Sparks metropolitan area. The installation of rocky riffles and raised channel bed elevations in the restored reaches may have increased the degree of surface–subsurface interaction. A fluctuating chloride concentration signal served as the tracer, induced by the variable influx of higher salinity water several miles upstream from the study reach. The solute transport model, OTIS, was used in conjunction with the hydrodynamic model, DYNHYD5, to estimate transient storage parameters under unsteady flow conditions. The model was calibrated to chloride concentrations measured over a period of three days at six in‐stream locations representing restored and un‐restored reaches. An automated parameter estimation algorithm (SCE‐UA) was used to optimize parameters for multiple reaches simultaneously and generate a distribution of parameter estimates. Results suggest that the transient storage zone cross‐sectional area (As) is larger in the restored reaches than in the unrestored reaches, but the exchange coefficient (α) is smaller, leading to increased hyporheic residence time and hydrologic retention in the vicinity of channel reconstructions. Scenarios were used to simulate the potential effects of increased subsurface residence time on denitrification and in‐stream NO3‐N concentrations. Monte Carlo analysis was performed to assess uncertainty in the simulation results and show the potential for greater nutrient retention in the lower Truckee River as a result of channel restoration. Copyright © 2009 John Wiley & Sons, Ltd.
Effects of a century of land cover and climate change on the hydrology of the Puget Sound basin
Authors: Cuo Lan , Lettenmaier Dennis P. , Alberti Marina , Richey Jeffrey E. 
Published: January 2009

AbstractThe Puget Sound basin in northwestern Washington, USA has experienced substantial land cover and climate change over the last century. Using a spatially distributed hydrology model (the Distributed Hydrology‐Soil‐Vegetation Model, DHSVM) the concurrent effects of changing climate (primarily temperature) and land cover in the basin are deconvolved, based on land cover maps for 1883 and 2002, and gridded climate data for 1915–2006. It is found that land cover and temperature change effects on streamflow have occurred differently at high and low elevations. In the lowlands, land cover has occurred primarily as conversion of forest to urban or partially urban land use, and here the land cover signal dominates temperature change. In the uplands, both land cover and temperature change have played important roles. Temperature change is especially important at intermediate elevations (so‐called transient snow zone), where the winter snow line is most sensitive to temperature change—notwithstanding the effects of forest harvest over the same part of the basin. Model simulations show that current land cover results in higher fall, winter and early spring streamflow but lower summer flow; higher annual maximum flow and higher annual mean streamflow compared with pre‐development conditions, which is largely consistent with a trend analysis of model residuals. Land cover change effects in urban and partially urban basins have resulted in changes in annual flow, annual maximum flows, fall and summer flows. For the upland portion of the basin, shifts in the seasonal distribution of streamflows (higher spring flow and lower summer flow) are clearly related to rising temperatures, but annual streamflow has not changed much. Copyright © 2009 John Wiley & Sons, Ltd.
Near real time satellite imagery to support and verify timely flood modelling
Authors: Di Baldassarre Giuliano , Schumann Guy , Bates Paul 
Published: January 2009

AbstractThe study investigates the capability of coarse resolution synthetic aperture radar (SAR) imagery to support flood inundation models. A hydraulic model of a 98‐km reach of the River Po (Northern Italy) was calibrated on the October 2000 high‐magnitude flood event with extensive and high‐quality field data. During the June 2008, low‐magnitude flood event a SAR image was acquired and processed in near real time (NRT) in order to provide adequate data for quick verification and recalibration of the hydraulic model. Copyright © 2009 John Wiley & Sons, Ltd.