bluuebunny/crossref_metadata_2025 huggingface dataset:
ON THE STRUCTURE OF i-CARBON
Authors: BUCKNUM MICHAEL J. , PICKARD CHRIS J. , STAMATIN IOAN , CASTRO EDUARDO A.
Published: June 2006

In the carbon science literature, there have been various reports over the past few decades of potentially novel crystalline forms of carbon emerging as nanometer scale fragments recovered from the explosive remnants of heated, shock compressed graphite and other precursors of C . Two nanometric and crystalline forms of C that are particularly prominent in these studies are known as n-diamond and i-carbon forms. In our previous work, we have shown that the commonly observed diffraction pattern of n-diamond nanocrystals, recorded by several research groups around the world, is consistent with the calculated diffraction pattern of a novel form of carbon that we propose to call glitter. Glitter is a tetragonal allotrope of carbon with a calculated density of ~3.08g/cm3, and the density functional theory (DFT) optimized lattice parameters given as a = 0.2560 nm and c = 0.5925 nm. In addition to the diffraction evidence for n-diamond having the glitter structure, the DFT calculated band structure of glitter shows it to be metallic, like the observed electrical characteristics of n-diamond. In this communication, we report on a comparison of the diffraction pattern observed for nanocrystalline i-carbon by the investigative team of Yamada et al. in 1994, with the calculated diffraction pattern of glitter based upon the optimized lattice parameters. The close fit of the latter dataset to that observed for i-carbon, as reported herein, suggests that indeed i-carbon may be of the same structure as n-diamond, and that they both may have the tetragonal glitter structure.
A COMPLETELY ENTANGLED SUBSPACE OF MAXIMAL DIMENSION
Authors: BHAT B. V. RAJARAMA
Published: June 2006

Consider a tensor product [Formula: see text] of finite-dimensional Hilbert spaces with dimension [Formula: see text], 1 ≤ i ≤ k. Then the maximum dimension possible for a subspace of [Formula: see text] with no non-zero product vector is known to be d1 d2…dk - (d1 + d2 + … + dk + k - 1. We obtain an explicit example of a subspace of this kind. We determine the set of product vectors in its orthogonal complement and show that it has the minimum dimension possible for an unextendible product basis of not necessarily orthogonal product vectors.
Mayan Historical Linguistics and Epigraphy: A New Synthesis
Authors: Wichmann Søren
Published: June 2006

Recent years have seen rapid advancement in our understanding of the phonology and grammar of Classic Ch'olan and the distribution of Lowland Mayan languages in the Classic period. The control over the data has advanced to such an extent that Classic Ch'olan should no longer be considered chiefly a product of reconstruction, but rather a language in its own right, providing fresh input to historical reconstruction. The interpretation of writing system principles has moved into the forefront of research, and recent discussions of these and other major issues are summarized here. This review suggests that the exceptional phonological transparency of the Maya script, which is a precondition for the current advances in linguistic epigraphy, is rooted in the need of scribes to spell out regional linguistic variants, and a sociolinguistically oriented theory of the evolution of writing in general is formulated and tested on the Mayan hieroglyphic materials.
Law and Social Movements: Contemporary Perspectives
Authors: McCann Michael
Published: June 2006

▪ Abstract  Social movement scholars have long seemed little interested in law, and traditional legal scholars were little interested in social movement analysis by social scientists. However, recent years have seen growth of interest in the topic of law and social movements, with inquiry led by political scientists and law and society scholars. This review surveys that diverse literature, beginning with general theory regarding core concepts and then moving to a review of empirical studies organized around the multi-stage model derived from political process approaches and legal mobilization frameworks. The primary argument of the review is that law is contingent, and how it matters for social movements varies with the context and character of struggle. Most analysts agree that law generally works to support status quo conventions and hierarchical relationships, but sometimes law can be mobilized to challenge and even reconstitute the terms of institutional order.
Transfer of lymphocytes from mice with renal ischemia can induce albuminuria in naive mice: a possible mechanism linking early injury and progressive renal disease?
Authors: Burne-Taney Melissa J. , Liu Manchang , Ascon Dolores , Molls Roshni R. , Racusen Lorraine , Rabb Hamid
Published: June 2006

Severe ischemia-reperfusion injury (IRI) predisposes to long-term impairment in kidney function both in patients and experimentally through unknown mechanisms. Given emerging evidence implicating lymphocytes in the pathogenesis of early injury to kidney, liver, and lung after IRI, we hypothesized that kidney IRI would potentially release or expose normally sequestered antigens that would lead to proliferation of antigen-recognizing lymphocytes. This, in turn, would directly participate in progressive kidney injury. To test this hypothesis, we purified splenic lymphocytes from C57BL/6 mice with severe renal IRI or sham operation 6 wk postischemia and transferred these cells to normal mice. Donor mice with IRI had significant fibrosis and cellular inflammation. The recipient mice were followed for 6 or 12 wk. Donor lymphocytes were found to traffic into recipient kidney. Twelve weeks after transfer, kidneys from mice which received IRI-primed lymphocytes exhibited significantly increased urinary albumin excretion compared with lymphocytes from sham mice. Splenic CD3+, CD4+, CD3+CD25+, and CD4+CD44+counts were significantly increased in mice after lymphocyte transfer from IRI mice vs. mice with lymphocytes from sham mice. These data demonstrate that lymphocytes from IRI mice can traffic to recipient kidney and directly mediate albuminuria. These data identify a novel mechanism by which initial kidney injury predisposes to long-term dysfunction and identify lymphocytes as potential therapeutic targets for progressive renal diseases.
Strengthening the Role of the Special Rapporteur on Freedom of Religion or Belief
Authors: Evans Carolyn
Published: June 2006

The Special Rapporteur holds the key United Nations mandate for the protection of freedom of religion and belief. This article gives an overview of the establishment and developing role of the Rapporteur and considers the way in which the three individuals who have held the office so far have carried out their mandate. It assesses the effectiveness of the methodologies used by the Rapporteur and, in particular, questions the shift of emphasis from prevention to protection. It then analyses the way in which the Rapporteurs have dealt with some of the substantive issues required by their role. The example of religious defamation is given to demonstrate the dangers of Rapporteurs taking overly simplistic approaches to complex issues. Finally a number of areas where further consideration is needed—in particular with respect to funding, the development of a treaty on religious freedom and the relationship with States—are briefly overviewed. The article concludes that the performance of the Rapporteurs have been exceptional, particularly given the limited financial resources allocated to the mandate and the complexities of the problems with which the mandate deals.
Evaluating Aspects of the Community Land and Atmosphere Models (CLM3 and CAM3) Using a Dynamic Global Vegetation Model
Authors: Bonan Gordon B. , Levis Samuel
Published: June 2006

The Community Land Model version 3 (CLM3) Dynamic Global Vegetation Model (CLM–DGVM) is used diagnostically to identify land and atmospheric model biases that lead to biases in the simulated vegetation. The CLM–DGVM driven with observed atmospheric data (offline simulation) underestimates global forest cover, overestimates grasslands, and underestimates global net primary production. These results are consistent with earlier findings that the soils in CLM3 are too dry. In the offline simulation an increase in simulated transpiration by changing this variable's soil moisture dependence and by decreasing canopy-intercepted precipitation results in better global plant biogeography and global net primary production. When CLM–DGVM is coupled to the Community Atmosphere Model version 3 (CAM3), the same modifications do not improve simulated vegetation in the eastern United States and Amazonia where the most serious vegetation biases appear. The dry bias in eastern U.S. precipitation is so severe that the simulated vegetation is insensitive to changes in the hydrologic cycle. In Amazonia, strong coupling among soil moisture, vegetation, evapotranspiration, and precipitation produces a highly complex hydrologic cycle in which small perturbations in precipitation are accentuated by vegetation. These interactions in Amazonia lead to a dramatic precipitation decrease and a collapse of the forest. These results suggest that the accurate parameterization of convection poses a complex and challenging scientific issue for climate models that include dynamic vegetation. The results also emphasize the difficulties that may arise when coupling any two highly nonlinear systems that have only been tested uncoupled.
The Low-Resolution CCSM3
Authors: Yeager Stephen G. , Shields Christine A. , Large William G. , Hack James J.
Published: June 2006

The low-resolution fully coupled configuration of the Community Climate System Model version 3 (CCSM3) is described and evaluated. In this most economical configuration, an ocean at nominal 3° resolution is coupled to an atmosphere model at T31 resolution. There are climate biases associated with the relatively coarse grids, yet the coupled solution remains comparable to higher-resolution CCSM3 results. There are marked improvements in the new solution compared to the low-resolution configuration of CCSM2. In particular, the CCSM3 simulation maintains a robust meridional overturning circulation in the ocean, and it generates more realistic El Niño variability. The improved ocean solution was achieved with no increase in computational cost by redistributing deep ocean and midlatitude resolution into the upper ocean and the key water formation regions of the North Atlantic, respectively. Given its significantly lower resource demands compared to higher resolutions, this configuration shows promise for studies of paleoclimate and other applications requiring long, equilibrated solutions.
Monsoon Regimes in the CCSM3
Authors: Meehl Gerald A. , Arblaster Julie M. , Lawrence David M. , Seth Anji , Schneider Edwin K. , Kirtman Ben P. , Min Dughong
Published: June 2006

Simulations of regional monsoon regimes, including the Indian, Australian, West African, South American, and North American monsoons, are described for the T85 version of the Community Climate System Model version 3 (CCSM3) and compared to observations and Atmospheric Model Intercomparison Project (AMIP)-type SST-forced simulations with the Community Atmospheric Model version 3 (CAM3) at T42 and T85. There are notable improvements in the regional aspects of the precipitation simulations in going to the higher-resolution T85 compared to T42 where topography is important (e.g., Ethiopian Highlands, South American Andes, and Tibetan Plateau). For the T85 coupled version of CCSM3, systematic SST errors are associated with regional precipitation errors in the monsoon regimes of South America and West Africa, though some aspects of the monsoon simulations, particularly in Asia, improve in the coupled model compared to the SST-forced simulations. There is very little realistic intraseasonal monsoon variability in the CCSM3 consistent with earlier versions of the model. Teleconnections to the tropical Pacific are well simulated for the South Asian monsoon.
Atmospheric Circulation and Its Effect on Arctic Sea Ice in CCSM3 Simulations at Medium and High Resolution*
Authors: DeWeaver Eric , Bitz Cecilia M.
Published: June 2006

The simulation of Arctic sea ice and surface winds changes significantly when Community Climate System Model version 3 (CCSM3) resolution is increased from T42 (∼2.8°) to T85 (∼1.4°). At T42 resolution, Arctic sea ice is too thick off the Siberian coast and too thin along the Canadian coast. Both of these biases are reduced at T85 resolution. The most prominent surface wind difference is the erroneous North Polar summer anticyclone, present at T42 but absent at T85.

An offline sea ice model is used to study the effect of the surface winds on sea ice thickness. In this model, the surface wind stress is prescribed alternately from reanalysis and the T42 and T85 simulations. In the offline model, CCSM3 surface wind biases have a dramatic effect on sea ice distribution: with reanalysis surface winds annual-mean ice thickness is greatest along the Canadian coast, but with CCSM3 winds thickness is greater on the Siberian side. A significant difference between the two CCSM3-forced offline simulations is the thickness of the ice along the Canadian archipelago, where the T85 winds produce thicker ice than their T42 counterparts. Seasonal forcing experiments, with CCSM3 winds during spring and summer and reanalysis winds in fall and winter, relate the Canadian thickness difference to spring and summer surface wind differences. These experiments also show that the ice buildup on the Siberian coast at both resolutions is related to the fall and winter surface winds.

The Arctic atmospheric circulation is examined further through comparisons of the winter sea level pressure (SLP) and eddy geopotential height. At both resolutions the simulated Beaufort high is quite weak, weaker at higher resolution. Eddy heights show that the wintertime Beaufort high in reanalysis has a barotropic vertical structure. In contrast, high CCSM3 SLP in Arctic winter is found in association with cold lower-tropospheric temperatures and a baroclinic vertical structure.

In reanalysis, the summertime Arctic surface circulation is dominated by a polar cyclone, which is accompanied by surface inflow and a deep Ferrel cell north of the traditional polar cell. The Arctic Ferrel cell is accompanied by a northward flux of zonal momentum and a polar lobe of the zonal-mean jet. These features do not appear in the CCSM3 simulations at either resolution.
The Dynamical Simulation of the Community Atmosphere Model Version 3 (CAM3)
Authors: Hurrell James W. , Hack James J. , Phillips Adam S. , Caron Julie , Yin Jeffrey
Published: June 2006

The dynamical simulation of the latest version of the Community Atmosphere Model (CAM3) is examined, including the seasonal variation of its mean state and its interannual variability. An ensemble of integrations forced with observed monthly varying sea surface temperatures and sea ice concentrations is compared to coexisting observations. The most significant differences from the previous version of the model [Community Climate Model version 3 (CCM3)] are associated with changes to the parameterized physics package. Results show that these changes have resulted in a modest improvement in the overall simulated climate; however, CAM3 continues to share many of the same biases exhibited by CCM3.

At sea level, CAM3 reproduces the basic observed patterns of the pressure field. Simulated surface pressures are higher than observed over the subtropics, however, an error consistent with an easterly bias in the simulated trade winds and low-latitude surface wind stress. The largest regional differences over the Northern Hemisphere (NH) occur where the simulated highs over the eastern Pacific and Atlantic Oceans are too strong during boreal winter, and erroneously low pressures at higher latitudes are most notable over Europe and Eurasia. Over the Southern Hemisphere (SH), the circumpolar Antarctic trough is too deep throughout the year.

The zonal wind structure in CAM3 is close to that observed, although the middle-latitude westerlies are too strong in both hemispheres throughout the year, consistent with errors in the simulated pressure field and the transient momentum fluxes. The observed patterns and magnitudes of upper-level divergent outflow are also well simulated by CAM3, a finding consistent with an improved and overall realistic simulation of tropical precipitation. There is, however, a tendency for the tropical precipitation maxima to remain in the NH throughout the year, while precipitation tends to be less than indicated by satellite estimates along the equator.

The CAM3 simulation of tropical intraseasonal variability is quite poor. In contrast, observed changes in tropical and subtropical precipitation and the atmospheric circulation changes associated with tropical interannual variability are well simulated. Similarly, principal modes of extratropical variability bear considerable resemblance to those observed, although biases in the mean state degrade the simulated structure of the leading mode of NH atmospheric variability.
A method for dynamic subtraction MR imaging of the liver
Authors: Mainardi Luca T , Passera Katia M , Lucesoli Agnese , Potepan Paolo , Setti Ernesto , Musumeci Renato
Published: June 2006

Background

Subtraction of Dynamic Contrast-Enhanced 3D Magnetic Resonance (DCE-MR) volumes can result in images that depict and accurately characterize a variety of liver lesions. However, the diagnostic utility of subtraction images depends on the extent of co-registration between non-enhanced and enhanced volumes. Movement of liver structures during acquisition must be corrected prior to subtraction. Currently available methods are computer intensive. We report a new method for the dynamic subtraction of MR liver images that does not require excessive computer time.

Methods

Nineteen consecutive patients (median age 45 years; range 37–67) were evaluated by VIBE T1-weighted sequences (TR 5.2 ms, TE 2.6 ms, flip angle 20°, slice thickness 1.5 mm) acquired before and 45s after contrast injection. Acquisition parameters were optimized for best portal system enhancement. Pre and post-contrast liver volumes were realigned using our 3D registration method which combines: (a) rigid 3D translation using maximization of normalized mutual information (NMI), and (b) fast 2D non-rigid registration which employs a complex discrete wavelet transform algorithm to maximize pixel phase correlation and perform multiresolution analysis. Registration performance was assessed quantitatively by NMI.

Results

The new registration procedure was able to realign liver structures in all 19 patients. NMI increased by about 8% after rigid registration (native vs. rigid registration 0.073 ± 0.031 vs. 0.078 ± 0.031, n.s., paired t-test) and by a further 23% (0.096 ± 0.035 vs. 0.078 ± 0.031, p < 0.001, paired t-test) after non-rigid realignment. The overall average NMI increase was 31%.

Conclusion

This new method for realigning dynamic contrast-enhanced 3D MR volumes of liver leads to subtraction images that enhance diagnostic possibilities for liver lesions.
Long-Term Progestin-Only Contraceptives Result in Reduced Endometrial Blood Flow and Oxidative Stress
Authors: Hickey M. , Krikun G. , Kodaman P. , Schatz Frederick , Carati C. , Lockwood C. J.
Published: June 2006

Context: Because of their safety and efficacy, long-term progestin-only contraceptives (LTPOCs) are well-suited for women with restricted access to health care. However, abnormal uterine bleeding (AUB) causes half of all users to discontinue therapy within 12 months. Endometria of LTPOC-treated patients display aberrant angiogenesis with abnormally enlarged, thin-walled, fragile blood vessels, inflammation, and focal hemorrhage. In this study, similar effects were observed with a new third-generation implantable LTPOC.

Objective: We hypothesized that LTPOC reduces uterine and endometrial blood flow, leading to hypoxia/reperfusion, which triggers the generation of reactive oxygen species. The latter induce aberrant angiogenesis, causing AUB.

Design: Endometrial perfusion was measured by laser-Doppler fluxmetry in women requesting LTPOCs. Endometrial biopsies were obtained for in vivo and in vitro experiments.

Setting: The study was conducted in the Yale University School of Medicine and Family-Planning Center in Western Australia.

Patients: Seven women 18 yr or older requesting implantable LTPOCs were recruited in Western Australia.

Intervention: Women received etonorgestrel implants.

Main Outcome: LTPOC treatment resulted in reduced endometrial perfusion and increased endometrial oxidative damage.

Conclusions: We propose that LTPOCs result in hypoxia reperfusion, which leads to aberrant angiogenesis resulting in AUB.
One Line at a Time
Authors: Gross Jan T.
Published: June 2006

The article calls for close reading of Holocaust testimonies and reminiscences.
Benzyltriphenylphosphonium Peroxodisulfate (PhCH2PPh3)2S2O8: a Mild and Inexpensive Reagent for Efficient Oxidation of Organic Compounds under Nonaqueous and Aprotic Conditions
Authors: Mohammadpoor-Baltork Iraj , Hajipour Abdol Reza , Mohammadi Hasan
Published: June 2006

Benzyltriphenylphosphonium peroxodisulfate is an easily prepared and stable reagent. It could be used as an oxidant under aprotic and nonaqueous conditions in organic solvents. This reagent oxidizes different classes of alcohols to carbonyl compounds, thiols to disulfides, sulfides to sulfoxides, oximes to carbonyl compounds and aromatic amines to azo compounds efficiently. α-Hydroxy carboxylic acids and phenylacetic acids undergo oxidative decarboxylation to produce carbonyl compounds.
Conformational Analysis of Oligomers of (R)-3-Hydroxybutanoic Acid in Solutions by 1H NMR Spectroscopy
Authors: Li Jun , Uzawa Jun , Doi Yoshiharu
Published: June 2006

Oligomers of (R)-3-hydroxybutanoic acid (3-HB) with different end groups and chain lengths have been prepared as model compounds of bacterial poly[(R)-3-hydroxybutanoate] [P(3-HB)]. They were studied in terms of their conformational behavior generated by rotation about CH2–CH bond of 3-HB units in solutions. The conformational behaviors of 3-HB oligomers were investigated in various solvents by analysis of vicinal coupling in the 500-MHz 1H NMR spectra. For all 3-HB oligomers studied in this work, 3-HB units without hydroxy group were found, in every solvent, to adopt similar conformational distributions to those of P(3-HB) polymer backbone in solutions, in which trans and gauche conformers are preferable, while the other gauche conformer is strongly disfavored. On the other hand, 3-HB units adjacent to hydroxy terminal group in 3-HB oligomers show different conformational behaviors relative to those of other 3-HB units. In non-polar organic solvents, only gauche conformer is predominant, due to the formation of an intramolecular hydrogen bond between hydroxy and carbonyl groups, while in polar organic solvents, the conformer distributions are similar to those of 3-HB units without hydroxy groups. In aqueous solution, for 3-HB units adjacent to hydroxy terminal group, the fractions of gauche conformer are still higher than those of trans conformer due to the formation of an intramolecular hydrogen bond.
High-Performance Liquid Chromatography Stationary Phases Based on π–π Electron Interaction. Aminopropyl Silica Gels Modified with Metal Phthalocyanines
Authors: Mifune Masaki , Shimomura Yuki , Saito Yutaka , Mori Yoshihiro , Onoda Midori , Iwado Akimasa , Motohashi Noriko , Haginaka Jun
Published: June 2006

Aminopropyl silica gels were modified with two porphyrin derivatives and five phthalocyanine derivatives. The modified silica gels were evaluated for the usefulness as high-performance liquid chromatography stationary phases for the separation of π-electron-rich polyaromatic hydrocarbons (PAHs) such as naphthalene and phenanthrene. As a result of the modification, the aminopropyl silica gels acquired a function of π–π electron interaction with PAHs. In particular, the aminopropyl silica gel modified with copper phthalocyanine (Cu-PCS) showed the strongest π–π electron interaction with PAHs. It was the most suited as a stationary phase for the separations of PAHs among the modified silica gels tested. The Cu-PCS column could be utilized for the separation of π-electron-rich compounds including medicines, mutagens, and pollutants.
Methane Hydroxylation on a Diiron Model of Soluble Methane Monooxygenase
Authors: Yoshizawa Kazunari , Ohta Takehiro , Yamabe Tokio
Published: June 2006

A concerted mechanism is proposed for the conversion of methane to methanol on intermediate Q of soluble methane monooxygenase (sMMO), the active species of which is considered to involve an Fe2(μ-O)2 diamond core. A hybrid density functional theory (DFT) method is used. Methane is highly activated on the dinuclear iron complex through the formation of the Q(CH4) complex, in which a four-coordinate iron plays a central role in the bonding interactions between intermediate Q and methane. An H atom abstraction via a four-centered transition state and a methyl migration via a three-centered transition state successively occur within the complex, leading to the formation of product methanol. The reaction pathway for the methane hydroxylation on the diiron complex follows the mechanism for the gas-phase reaction by the bare FeO+ complex described in a previous paper (K. Yoshizawa, Y. Shiota, and T. Yamabe, Chem. Eur. J., 3, 1160 (1997)). Our mechanism for the methane hydroxylation by sMMO is against a radical mechanism which has been widely believed to play a role in hydrocarbon hydroxylations by cytochrome P450.
Reactions of Phenyl(styryl)iodonium Tetrafluoroborate with Halide Ions
Authors: Okuyama Tadashi , Oka Hajime , Ochiai Masahito
Published: June 2006

Reactions of (E)-phenyl(styryl)iodonium tetrafluoroborate with chloride, bromide, and iodide ions are examined under various conditions. The products are those of substitution and elimination, involving (Z)-1-halo-2-phenylethene (2), phenylacetylene (3), and iodobenzene as main products as well as minor products of (E)-2 and 1-halo-1-phenylethene. Results of product analysis, UV absorption spectroscopy, and kinetic measurements are consistent with major pathways involving pre-equilibrium formation of halo-λ3-iodane and iodate intermediates, leading to the in-plane vinylic SN2 substitution to (Z)-2 and the intramolecular β-elimination to 3. The minor retained product (E)-2 is concluded to be formed through the vinylenebenzenium ion intermediate in 2,2,2-trifluoroethanol through the ligand coupling within the λ3-iodane intermediate in acetonitrile. 1-Bromo-1-phenylethene is considered to be derived from 3 by reaction with HBr formed during the reaction.
Fluorination of Orthothioesters through Oxidative Desulfurization–Fluorination
Authors: Furuta Satoru , Kuroboshi Manabu , Hiyama Tamejiro
Published: June 2006

The oxidative desulfurization-fluorination of orthothioesters of type RCH2C(SMe)3 using n-Bu4NH2F3 and 1,3-dibromo-5,5-dimethylhydantoin gave bromodifluorination products RCHBrCF2SMe in good yields. The products were converted into bromodifluoro olefins RCBr=CF2 via oxidation and thermolysis. In a similar way, the orthothioesters of type RCH(OH)C(SMe)3 or RCH(OAc)C(SMe)3 were fluorinated to afford difluoro ketones RCOCF2SMe or difluoro acetates RCH(OAc)CF2SMe, respectively. The difluoro acetates were reduced to RCH(OAc)CF2H by radical reduction. The mechanisms are discussed for difluorination accompanied by bromination or oxidation.
Reduction of Potassium Chromate By Tannins
Authors: Arakawa Hirohumi , Watanabe Norimoto , Tamura Rui , Rao Chebrolu Pulla
Published: June 2006

The reduction of potassium chromate has been carried out with several tannin substances, including gallic acid, pyrogallol, ethyl gallate, polygalloylglucose, and withered oak-leaf tannin. Each reaction was followed by colorimetry, EPR spectroscopy, electrochemistry, and molecular-sieve chromatography. The progress of the chromate reductions was monitored by measuring the VIS and EPR spectra as a function of time. The observed preudo-first-order reaction rate constants for Cr(III) formation were derived based on the intensities of the Cr(III) signals of the EPR spectra. Cyclic voltammograms of the simple reductants and their final Cr(III)-containing products formed from the reductions of chromate have also been measured. The formation of Cr(III)–tannin complexes was indicated by separation on a Sephadex G-25 column. The results obtained from VIS, EPR, and cyclic voltammetry were found to be mutually dependent, and showed close correlations among the data. The rate of reduction for Cr(VI) revealed the following trend: gallic acid > pyrogallol > ethyl gallate > polygalloylglucose > witheredoak-leaf tannin. The results obtained in the present study suggest that the rates of reduction for Cr(VI) in the tannins depend upon their peak oxidation potentials and stabilities for Cr(III)–tannin complexes.
Electrochemical Studies of Spinel LiMn2O4 Films Prepared by Electrostatic Spray Deposition
Authors: Nishizawa Matsuhiko , Uchiyama Takayuki , Dokko Kaoru , Yamada Kohta , Matsue Tomokazu , Uchida Isamu
Published: June 2006

An uniform, dense film of spinel LiMn2O4 (thickness, about 0.5 μm) was prepared by the electrostatic spray deposition method onto a Pt film electrode on Si substrate kept at 400 °C. Electrochemical properties of the LiMn2O4 film in a solution of 1 M LiClO4/propylene carbonate were studied by cyclic voltammetry and potential-step chronoamperometry. The oxidation and reduction of the film, which are accompanied by the extraction/insertion of lithium ions, proceeded almost quantitatively around 4 V vs. Li/Li+ with excellent coulombic reversibility. The apparent chemical diffusion coefficient of Li+ in Li1−xMn2O4 spinel phase varied on the order between 10−10 and 10−12 cm2 s−1 as a function of electrode potentials with minima at the potentials corresponding to the voltammetric current peaks.
High Photocurrent Quantum Yields in Short Wavelengths for Nanocrystalline Anatase-Type TiO2 Film Electrodes Compared with Those for Rutile-Type
Authors: Shiga Akira , Tsujiko Akira , Yae Shinji , Nakato Yoshihiro
Published: June 2006

Photoelectrochemical activity of nanocrystalline TiO2 film electrodes prepared by use of various TiO2 particles has been studied comparatively. It is confirmed that the photocurrent (or photoactivity) for anatase-type TiO2 is in general higher than that for the rutile-type. The photocurrent quantum yield (ηpc) for anatase-type TiO2 is nearly equal to that for rutile-type in long wavelengths but increases more and more with decreasing wavelength in contrast to the ηpc for rutile-type, and thus the ηpc for anatase-type becomes much higher than the ηpc for rutile-type in short wavelengths around 300 nm, indicating that the high photoactivity for anatase-type TiO2 is due to this high ηpc in short wavelengths. There are some discussions on the reasons for the high ηpc for anatase-type TiO2 in short wavelengths, including the possibility of contribution of hot electrons or holes in the TiO2 film.
Solvent Extraction of Copper(I) and Copper(II) from Aqueous Halide Solutions with Tetrabutylammonium Ions into Chloroform
Authors: Nasu Akinobu , Kato Koji , Sekine Tatsuya
Published: June 2006

The solvent extraction of copper(I) and copper(II) from 1 mol dm−3 Na(X, NO3), where X−is Cl−, Br−, or I−, as ion-pairs of anionic halide complexes with tetrabutylammonium ions (tba+) into chloroform was studied in the absence and presence of a reducing agent, ascorbic acid. The extraction of copper(II) with 2-thenoyltrifluoroacetone (Htta) in chloroform from these aqueous solutions was also studied. In the absence of ascorbic acid, the extraction of copper which was added as Cu2+ with tba+ was negligible from chloride and bromide solutions but tba+CuIII3− and (tba+)2CuIII42− were extracted from iodide solutions. In the presence of ascorbic acid, the extraction of tba+CuIX2− was found from all of these halide solutions. Only copper(II) was extracted with Htta from these solutions. The distribution ratio was lower when the halide concentration was higher due to formation of copper(II) complexes in the absence of ascorbic acid and it was much lower in the presence of this reducing agent due to formation of copper(I) complexes, which were stabler than the copper(II) complexes. From the extraction data with tba+ and with Htta, the formation constants of copper(I) and copper(II) halide complexes from Cu2+ in the aqueous phase as well as the extraction constants of certain complexes into the organic phase were determined. It was concluded that the dominant metal species in the aqueous phase was Cu2+ when the halide concentration was low even in the presence of the reducing agent and thus copper(I) anionic complexes were extracted into the organic phase and the molar ratio of copper(I) complex species to Cu2+ in the aqueous phase was higher at higher halide concentrations.
Infrared Spectroscopic Study of High Temperature Behavior of the Brønsted Acidic Hydroxyl Groups on Zeolites
Authors: Lee Byongjin , Kondo Junko N , Wakabayashi Fumitaka , Domen Kazunari
Published: June 2006

Quantitative analysis of the high-temperature behavior of the Brønsted acidic hydroxyl groups on H-ZSM-5 and H-mordenite zeolites was conducted by in situ IR spectroscopy. The integrated intensity of the Brønsted acidic hydroxyl band on H-ZSM-5 was decreased to 67% at 873 K compared with that at room temperature. This was considered to reflect the deprotonation of hydroxyls at high temperature. Attributing the decreased OH groups at high temperature region to the conversion to IR inactive dissociated species, we estimated the energy difference between the nondissociated and dissociated hydroxyls as 24 kJ mol−1 on H-ZSM-5.
Synthesis and Properties of Dihexylbithienoquinonoid Derivatives with Head-to-head, Head-to-tail, and Tail-to-tail Orientations
Authors: Higuchi Hiroyuki , Yoshida Shima , Uraki Yoshiyuki , Ojima Juro
Published: June 2006

2,2′-(Dihexyl-2,2′-bithienylidene-5,5′-diylidene)bis(propanedinitrile)s (dihexylbithienoquinonoid derivatives), in which two 3-hexylthiophene moieties are connected with head-to-tail (HT) and tail-to-tail (TT) orientations, were synthesized. HT bithienoquinonoid was isolated in a single form together with a small amount of its bromo derivative, similarly to the case for the head-to-head (HH) orientational isomer. On the other hand, TT isomer exhibited a peculiar feature in solution, affording an equilibrium mixture of two geometrical isomers. Electronic and electrochemical properties of these bithienoquinonoids were studied and compared with those of HH isomer. The results proved that all these bithienoquinonoid compounds possess highly polarizable and electron-acceptable properties. HH bithienoquinonoid was reduced through one two-electron transfer process, while HT and TT isomers were reduced through two one-electron transfer processes via stable radical anions to the corresponding dianions.
Studies on Active Species for Selective Catalytic Reduction of NO on Alumina-Supported Cobalt Oxide Catalysts
Authors: Nanba Tetsuya , Uemura Atsushi , Ueno Akifumi , Haneda Masaaki , Hamada Hideaki , Kakuta Noriyoshi , Miura Hiroshi , Ohfune Hitoshi , Udagawa Yasuo
Published: June 2006

Alumina-supported cobalt oxide catalysts were prepared by three different methods: The impregnation and sol/gel methods using either an acid or a base as a precipitant. The catalysts prepared by sol/gel methods, followed by calcination at 773 K, exhibited a significant activity for the selective catalytic reduction (SCR) of NO with propene as a reductant. The catalyst prepared by impregnation showed poor activity when it was calcined at 773 K, but exhibited enhanced activity when calcined at 1073 K. This is attributed to tiny CoAl2O4 crystallites formed during calcination of the catalyst at 1073 K. However, in sol/gel catalysts, finely-divided CoAl2O4 crystallites were formed during calcination, even at 773 K, because of the high dispersion of Co ions in the alumina support. Thus, the active species of alumina-supported cobalt oxide catalysts for SCR of NO with propene were concluded to be tiny CoAl2O4 crystallites dispersed on alumina.
Copper(II) Compounds Extended by 5-Carboxysalicylaldehyde and Its Schiff Bases: Interplay of Two Metal-Binding Sites and Intermolecular Stacking Contributing to Their Network and Bulk Structures
Authors: Sakamoto Reki , Ohba Masaaki , Fukita Nobuo , Takahashi Kazuhiro , Okawa Hisashi , Thompson Laurence K
Published: June 2006

5-Carboxysalicylaldehyde (H2casal) formed two mixed-ligand complexes, [Cu(Hcasal)(bpy)]ClO4 (1) and [Cu(casal)(bpy)]·2H2O (2) (bpy = 2,2′-bipyridine) and the Schiff bases H2L1 and H2L2 derived by condensing H2casal with N,N-dimethylethylenediamine and bis(3-aminopropyl)amine, respectively, formed [Cu(L1)]·0.25H2O (3) and [Cu(L2)]·H2O (4), respectively. X-Ray crystallographic studies were done for 1, [Cu(casal)(bpy)(MeOH)] (2′), [Cu(L1)]·4H2O (3′) and 4. 1: Monoclinic, space group C2/c, a = 18.457(5), b = 19.215(5), c = 12.237(3) Å, α = 90, β = 121.76(2), γ = 90°, V = 3690(1) Å3, and Z = 8. It has a dimeric structure with a perchlorato bridge between two [Cu(Hcasal)(bpy)]+ moieties. In the bulk the dimeric units are assembled by interligand noncovalent interactions providing a pseudo 2-D sheet. 2′: Monoclinic, space group P21/m, a = 9.791(4), b = 6.850(4), c = 25.56(1) Å, α = 90, β = 98.99(3), γ = 90°, V = 1692(1) Å3, and Z = 4. The casal2− combines one copper at the mixed-ligand site and the carboxylato group unidentately coordinates to the adjacent molecule, providing a 1-D zipper-like chain. The 1-D chains are further assembled through the interchain bpy/bpy stacking to form a pseudo 2-D network extended on the bc plane. 3′: Tetragonal, space group I41/a, a = b = 16.006(3), c = 27.745(7) Å, α = β = γ = 90°, V = 7108(2) Å3, and Z = 16. It has a 1-D helical structure extended by Cu–NNO(spacer)OO–Cu linkages along c axis (Fig. 6): The nearest Cu–Cu separation in the chain is 9.60 Å. The four water molecules exist in the helical column but are readily removed in the air. 4: Monoclinic, space group P21/c, a = 9.149(6), b = 17.566(6), c = 11.004(6)Å, α = 90, β = 110.03(4), γ = 90°, V = 1661(1) Å3, and Z = 4. It has a 1-D zigzag chain structure extended by Cu–NNNO(spacer)O–Cu linkages. Further, the 1-D chains align through noncovalent interchain interaction to provide a pseudo 2-D sheet. The interplay of the two dissimilar metal-binding sites of H2casal and its Schiff bases and the intermolecular noncovalent interaction contributing to the network and bulk structures of the complexes are discussed.
Multimetallic Activation of Molecular Hydrogen, Leading to Hydrogenation of the Coordinated Azulenes in Di-, Tri-, and Tetranuclear Ruthenium Carbonyl Complexes
Authors: Nagashima Hideo , Suzuki Akihiro , Nobata Mitsuharu , Aoki Katsuyuki , Itoh Kenji
Published: June 2006

Hydrogenation of di-, tri-, and tetranuclear ruthenium carbonyl complexes bearing guaiazulene or 4,6,8-trimethylazulene as the bridging ligand to bind the multimetallic framework was studied: [μ2 : η-guaiazulene)Ru2(CO)5 (1a)], [μ2 : η-4,6,8-trimethylazulene)Ru2(CO)5 (1b)], [(μ3 : η-guaiazulene)Ru3(CO)7 (2a)], [(μ3 : η-4,6,8-trimethylazulene)Ru3(CO)7 (2b)], [(μ3 : η-guaiazulene)Ru4(CO)9 (3a)], and [(μ3 : η-4,6,8-trimethylazulene)Ru4(CO)9 (3b)]. Reactions of these di-, tri-, and tetraruthenium complexes with dihydrogen (PH2 = 5—10 atm) at 100 °C resulted in cluster fragmentation and addition of five hydrogen atoms to the azulene ligands to form mononuclear ruthenium carbonyl hydride compounds, [(η5-pentahydroguaiazulenyl)RuH(CO)2 (4a)] or [(η5-pentahydrotrimethylazulenyl)RuH(CO)2 (4b)]. Despite potential formation of several stereoisomers dependent on the addition modes of hydrogen atoms, only one isomer of 4a or 4b was obtained in the hydrogenation. The crystal structure of a derivative of 4a revealed that the addition of hydrogen atoms occurred from the face of the azulene ligand originally bonded with the ruthenium species. Hydrogenation of the di-, tri-, and tetranuclear ruthenium complexes below 100 °C revealed that only the triruthenium compounds reacted with H2 at 50 °C via triruthenium dihydride intermediates: [(μ2: η-tetrahydroguaiazulene)Ru3H2(CO)7 (6a)] or [(μ2: η-tetrahydrotrimethylazulene)Ru3H2(CO)7 (6b)]; this indicates that there exists a reaction pathway to achieve facile activation of dihydrogen by the triruthenium clusters.
Angle-Resolved X-Ray Photoelectron Spectroscopic Study on a Self-Assembled Monolayer of a Porphyrin–Ferrocene–Thiol Linked Molecule on Gold: Evidence for a Highly Ordered Arrangement for Efficient Photoinduced Electron Transfer
Authors: Yanagida Masatoshi , Kanai Toshihito , Zhang Xue-Qun , Kondo Toshihiro , Uosaki Kohei
Published: June 2006

The orientation of a self-assembled monolayer (SAM) of the 5-(4-{8-[(11-mercaptoundecanoyl)ferrocenyl]octyloxy}phenyl)-10,15,20-triphenylporphyrin (PC8FcC11SH) molecule on a gold substrate, at which a photoinduced up-hill electron transfer with the highest quantum efficiency (>10%) ever reported was achieved, was investigated using angle-resolved X-ray photoelectron spectroscopy (ARXPS) combined with an electrochemical coverage determination. The total thickness and the distance between the Fe and the outermost part of the SAM of the PC8FcC11SH molecule was determined to be 44 and 29 Å, respectively, showing that while alkyl chains in the ferrocenecarbonylundecanethiol (FcC11SH) part of the PC8FcC11SH SAM should be oriented with a tilt angle of ca. 30° normal to the gold surface, the plane of the porphyrin ring should be almost surface-normal. This result suggests that one of the most important reasons for the very high photoconversion efficiency is the large separation between gold and the porphyrin ring, leading to a reduction in the reverse electron transfer and energy transfer quenching of the excited porphyrin state by gold.
Crystal Growth of Perylene Microcrystals in the Reprecipitation Method
Authors: Kasai Hitoshi , Oikawa Hidetoshi , Okada Shuji , Nakanishi Hachiro
Published: June 2006

The crystal growth of α-perylene microcrystals in the reprecipitation method was studied using of light-scattering technique and absorption spectroscopy. A certain model for microcrystallization has been established. The relationship between the reprecipitation conditions and the crystal size was clarified on the basis of this model. Especially, the water temperature was confirmed to be one of the most important parameters used to control the size of the microcrystals in the reprecipitation method. The apparent activation energy for the microcrystallization of perylene was estimated to be 68 kJ mol−1.
(η5-Cyclopentadienyl)(Halo or Acido)(Substituted 1-Methylthio-κS-ethylene-2-thiolato)cobalt(III): Formation, Stereoisomers, and Isomerization
Authors: Harada Takaaki , Takayama Chikako , Kajitani Masatsugu , Sugiyama Toru , Akiyama Takeo , Sugimori Akira
Published: June 2006

The addition of protic acids to (η5-cyclopentadienyl)(1-methylenethio)-κC,κS-ethylene-2-thiolato)cobalt(III) complexes (2) causes a Co–C bond cleavage in the three-membered cobaltathiirane ring to give (η5-cyclopentadienyl)(halo or acido)(1-methylthio-κS-ethylene-2-thiolato)cobalt(III) complexes (3). In the crystalline state, these complexes have either syn- or anti-configuration with respect to halo (or acido) and the methyl or substituted methyl group attached to S. In some cases, complexes 3 exist in equilibria between syn- and anti-stereoisomeric forms in solutions. In solutions, an exchange of the coordinated anions occurs very easily.
Effects of the Encapsulation of Alkali Ions into Iron(III) Complexes with a Macrocyclic Ring on Magnetic Properties
Authors: Maeda Yonezo , Suzuki Masaki , Hirose Shigeyuki , Hayami Shinya , Oniki Takayuki , Sugihara Shinji
Published: June 2006

New spin-crossover iron(III) complexes [FeM(salten)L]X with an alkali ion in a macrocycle have been prepared, and the magnetic properties of the complexes in the solid and in acetonitrile solution have been examined, where M is Li+, Na+, K+, or Rb+, H2salten is 4-aza-heptamethylene-1,7-bis(salicylideneiminate) and L is N-(4-picolyl)-aza-15-crown-5-ether. The spin-crossover behaviors of the iron(III) complexes dependent on temperature in the solid are observed on the Mössbauer spectra and magnetic susceptibilities, and those in acetonitrile on the electronic spectra. The magnetic properties of the complexes in the solid are changed with the species of alkali metal ions included in a macrocycle. Li-complexes show the magnetic moment of 4.00 B.M. at 300 K and 2.19 B.M. at 80 K, and Na-complexes 5.03 B.M. at 300 K and 4.21 B.M. at 80 K. The Mössbauer spectra of Li-complexes show that the interexchange rates of the spin-state transition between high-spin and low-spin states are as fast as the reciprocal of the lifetime of the excited state of 57Fe(10−7s) above 110 K. The magnetic behaviors of all of the complexes in acetonitrile are similar.
Synthesis of Gallium-sodalite from a Layered Silicate with a Half Cup-type Sodalite Cage Structure
Authors: Kiyozumi Yoshimichi , Ikeda Takuji , Hasegawa Yasuhisa , Nagase Takako , Mizukami Fujio
Published: June 2006

Gallium-sodalite (Ga-SOD) was synthesized from a half cup-type sodalite cage layered silicate (named; HLS: [(CH3)4N]2Na2 [Si10O20(OH)4] 5.6H2O) by solid-state transformation. HLS was easily converted to the Ga-SOD by mixing it with Ga(OH)3 and heating at 150 °C for 3 h after adding a small amount of H2O as the solvent. Ga was inserted into the T-site of the SOD cage obtained.
Solvent Switching of Stereoselectivity in [4 + 4] Photocyclodimerization of 2-Anthracenecarboxylic Acid
Authors: Mizoguchi Jun-ichi , Wada Takehiko , Inoue Yoshihisa
Published: June 2006

Stereochemistry of the major photocyclodimer is switched from 52% anti-head-to-head to 51% anti-head-to-tail among the four stereoisomers produced upon irradiation of 2-anthracenecarboxylic acid at low temperatures by changing the solvent from dichloromethane to methanol, through a critical control of the hydrogen bonding and dipole–dipole interactions.
Differences of the Mechanical Setup of Hip Simulators and Their Consequences on the Outcome of Hip Wear Testing
Authors: Reinisch G , Schoerg J , Leder E , Judmann KP , Plitz W , Franek F
Published: June 2006

The search for improved wear resistant materials for hip endoprostheses has lead to an international standard for wear testing of total hip joint prosthesis (ISO 14242). The displacement and load curves in this standard are derived from clinical gait analysis. However the standard leaves the interpretation of its displacement curves open since no coordinate system is defined in the document. By reviewing the development of the standard, the apparent coordinate system is identified and its application from both, an anatomical point of view and a technical perspective for designing hip simulators is explained. The study examines the coordinate transformations necessary for using common gait analysis data with the standard. On the basis of these transformations, the relative movements of the articulating surfaces are compared with existing hip simulators, the situation in vivo and the guidelines of the ISO standard. Thus possible consequences on the outcome of hip wear testing are discussed.