bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly Symmetrical Tetranuclear Cluster Complexes Supported by p‐tert‐Butylsulfonylcalix[4]arene as a Cluster‐Forming Ligand
Authors: Kajiwara Takashi , Kobashi Takanori , Shinagawa Reiko , Ito Tasuku , Takaishi Shinya , Yamashita Masahiro , Iki Nobuhiko 
Published: March 2006

AbstractSquare‐planar tetranuclear clusters [M4(L)(AcO)4(μ4‐OH)]– (M = MnII, CoII, and NiII) are synthesized using tetra‐anionic p‐tert‐butylsulfonylcalix[4]arene (L4–) as a cluster‐forming ligand. Three complexes are crystallographically isostructural, being crystallized in the triclinic crystal system with space group P$\bar {1}$. The calix[4]arene acts as a tetrakis fac‐tridentate ligand through four phenoxo and four sulfonyl oxygen atoms to form square arrangement of four metal ions, which are further bridged by four chelating acetate ions and one hydroxo ion in a μ4 manner to complete the hexacoordination of each metal center. Although the whole molecule of each complex is crystallographically independent, the molecule is highly symmetrical with a pseudo‐four‐fold axis lying on the μ4‐OH– group. The tetranuclear clusters are stable enough to maintain the core structures even in highly dilute solution (≈10 μM), which was confirmed by mass spectroscopic study, however, bridging acetates were easily exchanged by other carboxylate chelates to form derivatives such as [M4(L)(BzO)4(OH)]–. Metal–metal interactions were investigated by means of magnetic susceptibility, and it was revealed that both ferro‐ and antiferromagnetic interactions occur in the NiII complex depending on the bridging angles of Ni–O–Ni. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Utilization of high‐oleic rapeseed oil for deep‐fat frying of French fries compared to other commonly used edible oils
Authors: Matthäus Bertrand 
Published: March 2006

AbstractChanges in chemical, physical and sensory parameters of high‐oleic rapeseed oil (HORO) (NATREON™) during 72 h of deep‐fat frying of potatoes were compared with those of commonly used frying oils, palm olein (PO), high‐oleic sunflower oil (HOSO) and partially hydrogenated rapeseed oil (PHRO). In addition to the sensory evaluation of the oils and the potatoes, the content of polar compounds, oligomer triacylglycerols and free fatty acids, the oxidative stability by Rancimat, the smoke point and the anisidine value were determined. French fries obtained with HORO, PO and HOSO were still suitable for human consumption after 66 h of deep‐fat frying, while French fries fried in PHRO were inedible after 30 h. During the frying period, none of the oils exceeded the limit for the amount of polar compounds, oligomer triacylglycerols and free fatty acids recommended by the German Society of Fat Science (DGF) as criteria for rejection of used frying oils. After 72 h, the smoke point of all oils was below 150 °C, and the amount of tocopherols was reduced to 5 mg/100 g for PHRO and 15 mg/100 g for HORO and HOSO. Remarkable was the decrease of the oxidative stability of HOSO measured by Rancimat. During frying, the oxidative stability of this oil was reduced from 32 h for the fresh oil to below 1 h after 72 h of frying. Only HORO showed still an oxidative stability of more than 2 h. From the results, it can be concluded that the use of HORO for deep‐fat frying is comparable to other commonly used oils.
Bis‐methylene‐interrupted octadecadienoic fatty acids in Bulgarian bovine butter fats
Authors: Nikolova Diana , Antonova Daniela , Marekov Ilko , Nikolova‐Damyanova Boryana 
Published: March 2006

AbstractPreparative silver nitrate thin‐layer chromatography of fatty acid methyl esters and gas chromatography‐mass spectrometry of 4,4‐dimethyloxazoline derivatives were applied in combination to analyze the cis,cis octadecadienoic (18:2) fraction in commercial samples of bovine butter fat in Bulgaria. The main component, 9,12–18:2 was accompanied by a series of bis‐methylene‐interrupted isomers, cis,cis‐5,9‐; 6,10‐; 9,13‐ and 11,15–18:2, which were unambiguously identified by their specific mass spectra. The latter are characterized by the presence of very intensive diagnostic fragments which help to correctly locate the position of the double bond system in the carbon chain. The cis,cis‐5,9–18:2 isomer was found for the first time in butter fat, and the 6,10–18:2 isomer has not been described as yet.
Revisiting the formation of trans isomers during partial hydrogenation of triacylglycerol oils
Authors: Dijkstra Albert J. 
Published: March 2006

AbstractThe decisions to limit (Europe) or declare (USA) the trans isomer content of certain fatty foodstuffs have caused a demand for hardstocks with a reduced trans isomer content. One way to produce such hardstocks is by interesterifying high‐melting components such as palm stearin or fully hydrogenated vegetable oils with lauric or liquid oils. Another way is to modify the hydrogenation process. Possible modifications are reviewed. A moderate reduction in trans isomer content results from operating the hydrogenation process at much reduced temperature, but this also leads to an increase in saturates. Larger reductions in trans isomers may well be made possible by the recent development of new catalysts. One development involves the use of zeolites that allow the rather straight trans isomer to enter the pores while keeping the more curved cis isomers outside. The other development involves a precious metal catalyst that may have been modified in such a way that it has a reduced affinity for monounsaturated fatty acid moieties.
Photochemical, Electrochemical and Enzymatic Methods for Ether‐Bond Cleavage
Authors: Stolarzewicz Andrzej , Grobelny Zbigniew , Pisarski Wojciech , Łosiewicz Bożena , Piekarnik Beata , Swinarew Andrzej 
Published: March 2006

AbstractThe objective of this review is to outline the photochemical, electrochemical, and enzymatic methods that are currently used for ether‐bond cleavage. Key results have been extracted from publications covering the past 15 years of research activity in this field. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Perchloric Acid Impregnated on Silica Gel (HClO4/SiO2): A Versatile Catalyst for Michael Addition of Thiols to the Electron‐Deficient Alkenes
Authors: Khan Abu T. , Ghosh Subrata , Choudhury Lokman H. 
Published: March 2006

AbstractPerchloric acid adsorbed on silica gel (HClO4/SiO2) has been found to be a highly efficient and versatile catalyst for the Michael addition of thiols to a wide variety of conjugated alkenes such as α,β‐unsaturated ketones, carboxylic esters, nitriles, amides and chalcones in dichloromethane or methanol at room temperature. The reactions are completed within 2–20 min in high yields. Some of the additional advantages are: no aqueous work‐up is necessary, and the catalyst is also reusable. Moreover, the solid product can be obtained without chromatographic separation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Laboratory simulation of the salt weathering of schist: 1. Weathering of schist blocks in a seasonally wet tropical environment
Authors: Wells Tony , Binning Philip , Willgoose Garry , Hancock Greg 
Published: March 2006

AbstractData describing sediment generation focusing on the temporal evolution of size gradation are required for the prediction of long‐term landform evolution. This paper presents such data for the salt weathering of a quartz‐chlorite schist obtained from the Ranger Uranium Mine in northern Australia. Rock fragment samples are subjected to three different climate regimes: (1) a dry season climate; (2) a wet season climate (both based on observations at the Ranger site); and (3) an oven‐drying sequence designed to test the sensitivity of the weathering process by exposing the rocks to more extreme temperatures. Two MgSO4 salt solutions are applied, one being typical of wet season runoff and the other a more concentrated solution. Salt solution is applied daily in the wet season experiments and once only at the beginning of the dry season experiments. Results of the experiments reveal four stages of weathering. The kinetics of each stage are described and related to the formation of sediment of different sizes. Wet season climate conditions are shown to produce greater moisture variability and lead to faster weathering rates. However, salt concentrations in the wet season are typically lower and so when climate is combined with observed salt concentrations, the dry and wet season experiments weather at approximately equal rates. Finally, small variations in rock properties were shown to have a large impact on weathering rates, leading to the conclusion that rock weathering experiments need to be carefully designed if results are to be used to help predict weathering behaviour at the landscape scale. Copyright © 2006 John Wiley & Sons, Ltd.
Rock temperatures as an indicator of weathering processes affecting rock art
Authors: Hœrlé Stéphane 
Published: March 2006

AbstractTo aid rock art conservation, rock temperatures have been monitored at different depths and at low (30 min) and high (1 min) acquisition rates in a painted rock shelter in the uKhahlamba‐Drakensberg Park (South Africa). Preliminary data for winter (cold and dry) show that in that season cryoclasty is unlikely to occur (rare subzero thermal events and probable reduced moisture availability) and thermal shocks are improbable (highest measured ΔT/Δt < 2 °C min−1). High amplitude (about 30 °C) rock temperature cycles accompanied by reversals of the thermal gradient have been observed to occur almost daily and hint at the possibility of thermal stress fatigue. Copyright © 2006 John Wiley & Sons, Ltd.
Job separation in a non‐stationary search model: a structural estimation to evaluate alternative unemployment insurance systems
Authors: García‐Pérez J. Ignacio 
Published: March 2006

AbstractThis paper considers a job search model in which the environment is not constant throughout the unemployment spell and where jobs do not last for ever. In this situation, reservation wages can be lower than they would be in a model without consideration of such separations, but they can initially be higher precisely because of the non‐constant environment. The model is estimated structurally by using Spanish data for the period 1985–1996. The main finding is that, after controlling for unobserved heterogeneity, the unemployment hazard rate is almost flat during the first six months. However, after this duration, the highly decreasing job offer arrival rate comes to be the only significant factor, given that acceptance probabilities become equal to one. The estimated parameters are used to evaluate different unemployment insurance designs. We conclude that a non‐monotonic pattern in unemployment benefits, joint with a tax paid by workers and based on unemployment duration, makes this duration 13.2% lower than it currently is in Spain. Copyright © 2006 John Wiley & Sons, Ltd.
Estimation of multivariate models for time series of possibly different lengths
Authors: Patton Andrew J. 
Published: March 2006

AbstractWe consider the problem of estimating parametric multivariate density models when unequal amounts of data are available on each variable. We focus in particular on the case that the unknown parameter vector may be partitioned into elements relating only to a marginal distribution and elements relating to the copula. In such a case we propose using a multi‐stage maximum likelihood estimator (MSMLE) based on all available data rather than the usual one‐stage maximum likelihood estimator (1SMLE) based only on the overlapping data. We provide conditions under which the MSMLE isnot lessasymptotically efficient than the 1SMLE, and we examine the small sample efficiency of the estimators via simulations. The analysis in this paper is motivated by a model of the joint distribution of daily Japanese yen–US dollar and euro–US dollar exchange rates. We find significant evidence of time variation in the conditional copula of these exchange rates, and evidence of greater dependence during extreme events than under the normal distribution. Copyright © 2006 John Wiley & Sons, Ltd.
SG‐0: A small standard grid for DFT quadrature on large systems
Authors: Chien Siu‐Hung , Gill Peter M. W. 
Published: March 2006

AbstractWe report the development of a new standard quadrature grid for DFT calculations. Standard Grid 0 (SG‐0) is designed to be approximately half as large as, and to provide approximately half the accuracy of, the established SG‐1 grid. It is based on MultiExp and Lebedev quadrature for radial and angular coordinates, respectively. We find that SG‐0 is typically 50% faster than SG‐1 for energy, gradient, and hessian calculations for the exchange–correlation energy. This leads to a 35–38% speedup in the total gradient and hessian computations, and we particularly recommend its use for preliminary calculations on moderately large biochemical systems. It has been implemented as the default grid for DFT calculations in the Q‐Chem 3.0 package. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 730–739, 2006
Balancing an accurate representation of the molecular surface in generalized born formalisms with integrator stability in molecular dynamics simulations
Authors: Chocholoušová Jana , Feig Michael 
Published: March 2006

AbstractDifferent integrator time steps in NVT and NVE simulations of protein and nucleic acid systems are tested with the GBMV (Generalized Born using Molecular Volume) and GBSW (Generalized Born with simple SWitching) methods. The simulation stability and energy conservation is investigated in relation to the agreement with the Poisson theory. It is found that very close agreement between generalized Born methods and the Poisson theory based on the commonly used sharp molecular surface definition results in energy drift and simulation artifacts in molecular dynamics simulation protocols with standard 2‐fs time steps. New parameters are proposed for the GBMV method, which maintains very good agreement with the Poisson theory while providing energy conservation and stable simulations at time steps of 1 to 1.5 fs. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 719–729, 2006
Photochemical treatment with endosomally localized photosensitizers enhances the number of adenoviruses in the nucleus
Authors: Engesæter Birgit Ø. , Tveito Siri , Bonsted Anette , Engebraaten Olav , Berg Kristian , Mælandsmo Gunhild M. 
Published: March 2006

AbstractBackgroundIn the present study the physical targeting technique photochemical internalization (PCI) has been used in combination with adenovirus. We have previously shown that PCI enhances transgene expression from AdhCMV‐lacZ, and the aim of the present study was to further increase the understanding of photochemically mediated adenoviral transduction.MethodsTwo colorectal carcinoma cell lines, WiDr and HCT116, were pre‐incubated with the photosensitizer TPPS2a or methylene blue derivates (MBD) followed by infection with adenovirus and light exposure. Transgene expression was measured by flow cytometry. Real‐time polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH) were used to quantify the level of viral DNA in the nuclei. Real‐time PCR was also used to measure the level of β‐galactosidase mRNA in samples infected with AdhCMV‐lacZ.ResultsExposing TPPS2a‐treated cells to light enhanced the quantity of viral DNA in the nucleus, the mRNA level of the transgene and the transgene expression compared to non‐illuminated cells. The increased transgene expression was independent of the promoter used, but dependent on the time of light exposure and the cellular localization of the photosensitizer.ConclusionsThe enhanced transgene expression observed after photochemical treatment is most likely not a result of one event, but more an interplay between various mechanisms. An increased level of adenoviral DNA in the nucleus and a dependency of endosomal localization of the photosensitizer to obtain enhanced transgene expression suggested that endosomal rupture facilitated the transport of adenoviruses to the nucleus. Copyright © 2006 John Wiley & Sons, Ltd.
Aid, debt and fiscal policies in Senegal
Authors: Ouattara Bazoumana 
Published: March 2006

AbstractThis paper uses the fiscal response framework to study the effects of aid flows on key fiscal aggregates in Senegal, over the period of 1970–2000. Attention is given to the interplay between aid and debt. The paper contributes to the empirics of fiscal response modelling by deriving the standard errors and p values associated with the different mechanisms of the structural and reduced form equations. The main findings in this paper are: (i) relatively large shares of government resources are used to finance debt servicing; (ii) the impact of aid flows on domestic expenditure is statistically insignificant and (iii) debt servicing has a significant negative effect on domestic expenditure. The main policy implication of this study is that debt reduction could be a more effective policy tool than additional aid (loans) in financing pro‐poverty expenditure as well as public investment. Copyright © 2006 John Wiley & Sons, Ltd.
Incidentally detected lesions on contrast‐enhanced MR imaging in candidates for breast‐conserving therapy: Correlation between MR findings and histological diagnosis
Authors: Yabuuchi Hidetake , Kuroiwa Toshiro , Kusumoto Chie , Fukuya Tatsuro , Ohno Shinji , Hachitanda Yoichi 
Published: March 2006

AbstractPurposeTo investigate the correlation between MR findings and the histological diagnosis of incidentally detected lesions in candidates for breast‐conserving therapy.Materials and MethodsMR images of 299 patients with breast cancer were reviewed. Incidentally detected lesions were noted in 59 of 299 (20%) patients, and a histological diagnosis was obtained in 48 of 59 (81%) patients. There were 25 benign and 23 malignant lesions. The number, size, location, morphologic character, and kinetic curve assessment of the MR findings were analyzed. Statistical analyses were performed to determine whether any differences could be observed between benign and malignant lesions.ResultsLesions of over 10 mm tended to be malignant (11/16; 69%), whereas those equal or less than 5 mm tended to be benign (12/17; 71%; P < 0.05). Lesions in the same quadrant as the main lesion tended to be malignant (20/27.5; 73%), whereas those in a different quadrant tended to be benign (17.5/20.5; 85%; P < 0.001). Lesions with early peak of enhancement tended to be malignant (20/25; 80%), whereas those with persistent enhancement tended to be benign (20/23; 87%; P < 0.001).ConclusionIncidentally detected lesions that are found in a different quadrant from the main lesion, are smaller than 10 mm in diameter, and show persistent enhancement on MR imaging suggest benign lesions. Therefore, patients with such lesions should avoid unnecessary surgical procedures unless lesions are proved to be malignant by cytology or biopsy. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
MRI features of pediatric cerebral paragonimiasis in the active stage
Authors: Zhang Jin Song , Huan Yi , Sun Li Jun , Zhang Guang Yun , Ge Ya Li , Zhao Hai Tao 
Published: March 2006

AbstractWe retrospectively reviewed the MR images of the brains of six children (age = 5–13 years) who had cerebral paragonimiasis in the early active stage. Diagnosis was based on a positive antibody test enzyme‐linked immunosorbent assay (ELISA) for paragonimiasis in serum. The most common finding (in five patients) was irregular hemorrhage of various degrees. Moreover, in three cases some multiple irregular lesions with surrounding edema appeared to be conglomerated and aggregated. The rare appearance (in one patient) was a “tunnel sign,” which showed the migrating track of the adult worm. In one patient with abscess and minimal hemorrhage, diffusion‐weighted imaging (DWI) showed a heterogeneous high signal of lesions. Other findings included slight (one patient) or marked (one patient) irregular contrast enhancement, and large edematous areas surrounding small centers of hemorrhage (two patients). MR findings of conglomerated lesions with hemorrhage or tunnel sign may help to establish the diagnosis of active‐stage cerebral paragonimiasis. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Composite right/left‐handed extended equivalent circuit (CRLH‐EEC) FDTD: stability and dispersion analysis with examples
Authors: Rennings A. , Otto S. , Caloz C. , Lauer A. , Bilgic W. , Waldow P. 
Published: March 2006

AbstractA composite right/left‐handed (CRLH) extended equivalent circuit (EEC) FDTD method with a stability criterion based on a Liapunov discrete energy function is presented and applied to investigate several transient and refractive phenomena occurring at the interface between a CRLH metamaterial (MTM) and a purely right‐handed (PRH) structure. This formulation consists in an extension of the equivalent circuit (EC) Yee scheme including a left‐handed (LH) series capacitance and shunt inductance in addition to the canonical right‐handed (RH) series inductance and shunt capacitance, so as to model general CRLH transmission line (TL) MTMs. This CRLH‐EEC FDTD scheme is shown to represent a convenient numerical scheme, with remarkable formulation compactness and high computational efficiency, for the analysis of any type of MTM structure. Moreover, this scheme, coupled with a Y‐matrix representation of the EEC Yee cell, is shown to rigorously restore the dispersion/attenuation relation of CRLH MTMs. Transient solutions for the propagation of a modulated Gaussian pulse through a PRH–CRLH interface highlights interesting effects such as space‐domain compression, infinite phase velocity modulation and the well‐known backward wave effect. Frequency‐domain analysis of the fields radiated by dipoles through the Veselago–Pendry lens shows how focusing is affected both qualitatively and quantitatively by the orientation of the dipoles. Copyright © 2006 John Wiley & Sons, Ltd.
Efficient full‐wave analysis method of leaky‐wave modes in periodically loaded dielectric waveguides with application to backward‐to‐forward frequency‐scannable antennas and metamaterials
Authors: Luis Gómez‐Tornero José , Pascual García Juan , Álvarez‐Melcón Alejandro 
Published: March 2006

AbstractThis work presents a novel and efficient full‐wave method specifically conceived for the modal analysis of periodic planar metallizations printed on the open side of a dielectric rectangular waveguide. This particular type of structures can be used to conceive interesting backward‐to‐forward frequency‐scanning periodic leaky‐wave antennas, including leaky‐wave antennas based on the composite right–left‐handed transmission line concept (metamaterial). For the analysis, the spectral‐domain Green's functions are obtained by expanding the electromagnetic fields as a double summation of Floquet and parallel‐plate modes. An original and simple coupled equivalent circuit is used to deal with the multilayered stratification arrangement and the top radiation boundary. The method of moments (MoM) is applied to solve the corresponding EFIE/MFIE, and an original iterative technique is used to search for the complex leaky‐wave mode zeros of the determinant of the MoM matrix. All the expressions are in closed form, while keeping its full‐wave nature. The convergence and the accuracy of the method are both studied. Once the backward leaky‐waves are found, some interesting phenomena are examined, such as backward‐to‐forward beam scanning, appearance of bandgaps, mode coupling, multi‐space‐harmonic radiation, and antenna aperture illumination control. By studying a practical antenna and by comparing with previously published methods, it is shown the importance of a full‐wave analysis tool that can take into account all the aforementioned effects. Copyright © 2006 John Wiley & Sons, Ltd.