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171.
Laura Gherardi Daniela Bettinelli Sergio Spreafico Fedor G m ry 《Physica C: Superconductivity and its Applications》1998,310(1-4):52-56
Transport AC losses measured in self-field conditions on multifilamentary Bi-2223 tapes are often found to be lower than those calculated within the framework of the critical state model for a bulk wire with elliptical cross section, though generally higher than predicted for a strip. This effect is sometimes ascribed to the non-ideal geometry of the tapes, which does not exactly reproduce either shape. Here we propose an alternative explanation assuming that the critical current density of superconducting material depends on magnetic field. In practice, we analyzed the AC loss curve and deduced different Ic values for the individual data points, using the standard Norris equation for elliptical conductor. This gives the relation between ‘calculated' Ic and the self-field associated to AC transport current, which can be regarded as an alternative way to qualify the dependence of Jc on magnetic field. Important is that this procedure covers the range of fields below the self-field at Ic where the measurement in background DC field can not be used to determine Jc(B). 相似文献
172.
A boundary version of Ahlfors’ Lemma is established and used to show that the classical Schwarz-Carathéodory reflection principle
for holomorphic functions has a purely conformal geometric formulation in terms of Riemannian metrics. This conformally invariant
reflection principle generalizes naturally to analytic maps between Riemann surfaces and contains among other results a characterization
of finite Blaschke products due to M. Heins.
D. Kraus was supported by a HWP scholarship
O. Roth and S. Ruscheweyh received partial support form the German-Israeli Foundation (grant G-809-234.6/2003) 相似文献
173.
Erika Szunyogová Katarína Györyová Daniela Hudecová Lenka Piknová J. Chomič Zuzanna Vargová V. Zeleňák 《Journal of Thermal Analysis and Calorimetry》2007,88(1):219-223
The thermal decomposition of the complexes Zn(form)2⋅2phen
(I), Zn(ac)2⋅2phen
(II), Zn(prop)2⋅2phen
(III), Zn(but)2⋅2phen
(IV), where phen=phenazone, form=formiate,
ac=acetate, prop=propionate, but=butyrate has been studied in air by TG/DTG
and DTA methods. The possible mechanism of the thermal decomposition was proposed.
The final product of thermal decomposition was ZnO. IR data show unidentate
coordination of carboxylate group to Zn(II) ion. The complexes were tested
against various strains of microorganisms and their efficiency decrease in
the sequence yeasts >bacteria>filamentous fungi. 相似文献
174.
Hari M. Gupta José R. Campanha Daniela R. de Aguiar Gabriel A. Queiroz Charu G. Raheja 《Physica A》2007
We study the statistical distribution of firm size for USA and Brazilian publicly traded firms through the Zipf plot technique. Sale size is used to measure firm size. The Brazilian firm size distribution is given by a log-normal distribution without any adjustable parameter. However, we also need to consider different parameters of log-normal distribution for the largest firms in the distribution, which are mostly foreign firms. The log-normal distribution has to be gradually truncated after a certain critical value for USA firms. Therefore, the original hypothesis of proportional effect proposed by Gibrat is valid with some modification for very large firms. We also consider the possible mechanisms behind this distribution. 相似文献
175.
Daniela Meloni Alcide di Sarra Giorgio Fiocco 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,93(4):397-413
The vertical profile of Saharan dust in the atmosphere is generally characterized by a large aerosol concentration in the mid troposphere, differently from the climatological distribution of other types of particles, that show a peak at the surface and a rapid decrease with height. Saharan dust is also characterized by particles of relatively large size of irregular shape, and variable values of the single scattering albedo (the ratio between radiation scattering and extinction). The dust's peculiar vertical distribution is expected to produce an effect on the calculation of the direct aerosol radiative forcing at the surface and at the top of the atmosphere. This effect is investigated by comparing estimates of aerosol direct visible radiative forcing at the surface and at the top of the atmosphere for dust vertical profiles measured in the Mediterranean, and for the climatological profile. The radiative forcing is estimated by means of an accurate radiative transfer model, and for the ocean surface. The sensitivity of the results on the solar zenith angle, aerosol optical depth, and aerosol absorption is also investigated. The aerosol radiative forcing at the surface shows a very small dependency on the aerosol vertical profile. At the top of the atmosphere, the radiative forcing is weakly dependent on the vertical profile (up to 10% variation on the daily average forcing) for low absorbing particles; conversely, it shows a strong dependency (the daily radiative forcing may vary up to 100%) for absorbing particles. The top of the atmosphere visible radiative forcing efficiency produced by dust having single scattering albedo <0.7 is higher by 4 W m−2 when the observed vertical profile instead of the standard profile is used in the calculations (i.e. it produces a lower cooling). For values of the single scattering albedo around 0.67, the sign of the forcing depends on the vertical profile. The influence of the vertical distribution on the radiative forcing is largest at small values of the solar zenith angle, and at short wavelengths. 相似文献
176.
Nikolai Kuhnert Daniela Göbel Caroline Thiele Benjamin Renault Bing Tang 《Tetrahedron letters》2006,47(38):6915-6918
The N-alkylation and N-acylation reactions of trianglamine macrocycles are described leading to an efficient synthesis of enantiomerically pure functionalised hexa-amide and hexa-amine trianglamine macrocycles. 相似文献
177.
Cover Picture: Robust Chemical Preservation of Digital Information on DNA in Silica with Error‐Correcting Codes (Angew. Chem. Int. Ed. 8/2015)
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178.
Organocatalytic,Asymmetric Eliminative [4+2] Cycloaddition of Allylidene Malononitriles with Enals: Rapid Entry to Cyclohexadiene‐Embedding Linear and Angular Polycycles
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Dr. Nicoletta Brindani Dr. Gloria Rassu Dr. Luca Dell'Amico Dr. Vincenzo Zambrano Dr. Luigi Pinna Dr. Claudio Curti Dr. Andrea Sartori Prof. Dr. Lucia Battistini Prof. Dr. Giovanni Casiraghi Prof. Dr. Giorgio Pelosi Dr. Daniela Greco Prof. Dr. Franca Zanardi 《Angewandte Chemie (International ed. in English)》2015,54(25):7386-7390
A direct aminocatalytic synthesis has been developed for the chemo‐, regio‐, diastereo‐, and enantioselective construction of densely substituted polycyclic carbaldehydes containing fused cyclohexadiene rings. The chemistry utilizes, for the first time, remotely enolizable π‐extended allylidenemalononitriles as electron‐rich 1,3‐diene precursors in a direct eliminative [4+2] cycloaddition with both aromatic and aliphatic α,β‐unsaturated aldehydes. The generality of the process is demonstrated by approaching 6,6‐, 5,6‐, 7,6‐, 6,6,6‐, and 6,5,6‐fused ring systems, as well as biorelevant steroid‐like 6,6,6,6,5‐ and 6,6,6,5,6‐rings. A stepwise reaction mechanism for the key [4+2] addition is proposed as a domino bis‐vinylogous Michael/Michael/retro‐Michael reaction cascade. The utility of the malononitrile moiety as traceless activating group of the dicyano nucleophilic substrates is demonstrated. 相似文献
179.
Mono‐, di‐ and trimethylated homologues of isoprenoid tetraether lipid cores in archaea and environmental samples: mass spectrometric identification and significance
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Chris Knappy Daniela Barillà James Chong Dominic Hodgson Hugh Morgan Muhammad Suleman Christine Tan Peng Yao Brendan Keely 《Journal of mass spectrometry : JMS》2015,50(12):1420-1432
Higher homologues of widely reported C86 isoprenoid diglycerol tetraether lipid cores, containing 0–6 cyclopentyl rings, have been identified in (hyper)thermophilic archaea, representing up to 21% of total tetraether lipids in the cells. Liquid chromatography‐tandem mass spectrometry confirms that the additional carbon atoms in the C87‐88 homologues are located in the etherified chains. Structures identified include dialkyl and monoalkyl (‘H‐shaped’) tetraethers containing C40‐42 or C81‐82 hydrocarbons, respectively, many representing novel compounds. Gas chromatography‐mass spectrometric analysis of hydrocarbons released from the lipid cores by ether cleavage suggests that the C40 chains are biphytanes and the C41 chains 13‐methylbiphytanes. Multiple isomers, having different chain combinations, were recognised among the dialkyl lipids. Methylated tetraethers are produced by Methanothermobacter thermautotrophicus in varying proportions depending on growth conditions, suggesting that methylation may be an adaptive mechanism to regulate cellular function. The detection of methylated lipids in Pyrobaculum sp. AQ1.S2 and Sulfolobus acidocaldarius represents the first reported occurrences in Crenarchaeota. Soils and aquatic sediments from geographically distinct mesotemperate environments that were screened for homologues contained monomethylated tetraethers, with di‐ and trimethylated structures being detected occasionally. The structural diversity and range of occurrences of the C87‐89 tetraethers highlight their potential as complementary biomarkers for archaea in natural environments. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
180.
Multitarget Drug Discovery for Alzheimer's Disease: Triazinones as BACE‐1 and GSK‐3β Inhibitors
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Federica Prati Dr. Angela De Simone Dr. Paola Bisignano Dr. Andrea Armirotti Dr. Maria Summa Dr. Daniela Pizzirani Dr. Rita Scarpelli Dr. Daniel I. Perez Prof. Dr. Vincenza Andrisano Dr. Ana Perez‐Castillo Prof. Dr. Barbara Monti Francesca Massenzio Dr. Letizia Polito Prof. Dr. Marco Racchi Dr. Angelo D. Favia Dr. Giovanni Bottegoni Prof. Dr. Ana Martinez Prof. Dr. Maria Laura Bolognesi Prof. Dr. Andrea Cavalli 《Angewandte Chemie (International ed. in English)》2015,54(5):1578-1582
Cumulative evidence strongly supports that the amyloid and tau hypotheses are not mutually exclusive, but concomitantly contribute to neurodegeneration in Alzheimer′s disease (AD). Thus, the development of multitarget drugs which are involved in both pathways might represent a promising therapeutic strategy. Accordingly, reported here in is the discovery of 6‐amino‐4‐phenyl‐3,4‐dihydro‐1,3,5‐triazin‐2(1H)‐ones as the first class of molecules able to simultaneously modulate BACE‐1 and GSK‐3β. Notably, one triazinone showed well‐balanced in vitro potencies against the two enzymes (IC50 of (18.03±0.01) μM and (14.67±0.78) μM for BACE‐1 and GSK‐3β, respectively). In cell‐based assays, it displayed effective neuroprotective and neurogenic activities and no neurotoxicity. It also showed good brain permeability in a preliminary pharmacokinetic assessment in mice. Overall, triazinones might represent a promising starting point towards high quality lead compounds with an AD‐modifying potential. 相似文献