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41.
Tebano A Aruta C Sanna S Medaglia PG Balestrino G Sidorenko AA De Renzi R Ghiringhelli G Braicovich L Bisogni V Brookes NB 《Physical review letters》2008,100(13):137401
Linear dichroism (LD) in x-ray absorption, diffraction, transport, and magnetization measurements on thin La(0.7)Sr(0.3)MnO(3) films grown on different substrates, allow identification of a peculiar interface effect, related just to the presence of the interface. We report the LD signature of preferential 3d-e(g)(3z(2)-r(2)) occupation at the interface, suppressing the double exchange mechanism. This surface orbital reconstruction is opposite to that favored by residual strain and is independent of dipolar fields, the chemical nature of the substrate and the presence of capping layers. 相似文献
42.
43.
An attempt has been made to resolve (diallylether) platinum(II) chloride. The complex was transformed by methoxide addition to a binuclear product containing carbon-platinum σ bonds. After bridge splitting of the binuclear alkyl derivative with (S)-α-methylbenzylamine, fractional crystallization gave two diastereoisomer complexes. Treatment of these with HCl gave optically inactive (diallylether)platinum(II) ch1oride. The molecular structure of one diastereoisomeric product was established by X-ray analysis. 相似文献
44.
Serventi S Allodi G De Renzi R Guidi G Romanò L Manfrinetti P Palenzona A Niedermayer Ch Amato A Baines Ch 《Physical review letters》2004,93(21):217003
We have measured the transverse field muon spin precession in the flux-lattice (FL) state of the two-gap superconductor MgB2 and of the electron doped compounds Mg(1-x)AlxB2 in magnetic fields up to 2.8 T. We show the effect of the two gaps on the internal field distribution in the FL, from which we determine two coherence length parameters and the doping dependence of the London penetration depth. This is an independent determination of the complex vortex structure already suggested by the STM observation of large vortices in a MgB2 single crystal. Our data agree quantitatively with STM and we thus validate a new phenomenological model for the internal fields. 相似文献
45.
We performed zero and transverse field muon spin rotation experiments on a large number of YBa2Cu3O6+x samples. We detect the coexistence of antiferromagnetic (AF) short range magnetism with superconductivity below T(f) < or = 10 K in compositions 0.37 < or = x < or = 0.39. Most muons experience local AF fields, even when a SQUID detects a full superconducting volume fraction, which points to a local minimal interference organization of short AF stripes embedded in the superconductor. A detailed phase diagram is produced and the consequences of the minimal interference are discussed. 相似文献
46.
<正> 在结合环交换条件的讨论中,Tominaga,H得到一个重要的结果:如果半素环的任一换位子xy-yx含于环的中心,那么这个环是可换环。本文推广了这一定理的结果,并给出与文中完全不同的证明。在本文中,R总表示结合环,Z表示R的中心,而且记[x,y]=xy-yx。 相似文献
47.
Ernesto Di Cesare Antonella Costanzi Francesco Fedele Paolo Di Renzi Giuseppe D'Eusanio Luciano Lupattelli Roberto Passariello 《Magnetic resonance imaging》1996,14(10):1149-1156
In most cases, surgery of aortic dissections repairs only the ascending portion of the aorta, leaving a residual dissection in the arch and descending aorta. We studied 17 patients operated upon for type A aortic dissection. A total of 42 magnetic resonance imaging (MRI) examinations were performed, with two to five studies per patient (mean 2.47). The studies were done between 5 weeks and 47 months (mean 17.5 months) after surgery. The patients were evaluated by MRI using gated spin-echo and gradient-echo sequences on axial and oblique sagittal views, and in selected cases, coronal views. A high incidence of abnormalities was observed. Pericardial hematoma was observed in 11% of cases, aortic and branch involvement in 41%, abdominal aortic branch involvement in 47%, dilatation of native aorta in 58%, and extension of dissection in 10%. New complications were detected during follow-up in 53% of patients. MRI was helpful in the follow-up of patients operated upon for aortic dissections, owing to its noninvasiveness and multiplanarity. By means of this technique, it was possible to obtain information about the natural history of the disease, as well as information useful for subsequent treatment. 相似文献
48.
V. De Renzi 《Surface science》2009,603(10-12):1518-1525
In this work, I review our recent results on the electronic properties of thiolate/metal interface. Work function change, molecular level alignment and interfacial state formation of the methylthiolate/Au(1 1 1) and dimethyl-disulfide/Au(1 1 1) interfaces are investigated by means of UPS and XPS. A complete picture of the electronic properties of both the dimethyl-disulfide (DMDS) weakly-adsorbed and the methylthiolate (MT) chemisorbed phases is obtained by direct quantitative comparison between the experiment and theory. The modifications of the electronic properties of the DMDS thin film, induced by a MT buffer layer are also discussed.Moreover, the cysteine/Au(1 1 1) system is investigated as an example of interface formed by molecules with large intrinsic dipole moment. Finally, surface inhomogeneity and its influence on the interface electronic properties is briefly discussed, in light of the important concept of local work function. 相似文献
49.
Valeria Di Bussolo Ileana FrauLorenzo Checchia Lucilla FaveroMauro Pineschi Gloria Uccello-BarrettaFederica Balzano Graziella RoselliGabriele Renzi Paolo Crotti 《Tetrahedron》2011,67(25):4696-4709
The new racemic diastereoisomeric epoxides 6α and 6β, the carba analogs of the corresponding d-galactal- and d-allal-derived allyl epoxides have been synthesized and their regio- and stereoselective behavior examined in addition reactions with model O-, C-, N-, and S-nucleophiles. The results have indicated that epoxide 6β has a pronounced tendency toward anti-1,2-addition, whereas epoxide 6α shows interesting levels of syn- and/or anti-1,4-addition processes. A chiral recognition process found with epoxide 6β, turned out to be consistently reduced in epoxide 6α. All the results have been rationalized on the basis of conformational, steric, and stereoelectronic effects. 相似文献
50.
Kinetic Resolution of Oxazinones: Rational Exploration of Chemical Space through the Design of Experiments
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Polyssena Renzi Christel Kronig Dr. Armando Carlone Dr. Serap Eröksüz Prof. Dr. Albrecht Berkessel Dr. Marco Bella 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(37):11768-11775
The organocatalytic kinetic resolution of 4‐substituted oxazinones has been optimised (selectivity factor S up to 98, chiral oxazinone ee values up to 99.6 % ( 1 a – g ) and product ee values up to 90 % ( 3 a – g )) in a rational way by applying the Design of Experiments (DoE) approach. 相似文献