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2.
Ihor R. Muts Falko M. Schappacher Vasyl’ I. Zaremba 《Journal of solid state chemistry》2007,180(8):2202-2208
New indides SrAu3In3 and EuAu3In3 were synthesized by induction melting of the elements in sealed tantalum tubes. Both indides were characterized by X-ray diffraction on powders and single crystals. They crystallize with a new orthorhombic structure type: Pmmn, Z=2, a=455.26(9), b=775.9(2), c=904.9(2) pm, wR2=0.0425, 485 F2 values for SrAu3In3 and a=454.2(2), b=768.1(6), c=907.3(6) pm, wR2=0.0495, 551 F2 values for EuAu3In3 with 26 variables for each refinement. The gold and indium atoms build up three-dimensional [Au3In3] polyanionic networks, which leave distorted hexagonal channels for the strontium and europium atoms. Within the networks one observes Au2 atoms without Au-Au contacts and gold zig-zag chains (279 pm Au1-Au1 in EuAu3In3). The Au-In and In-In distances in EuAu3In3 range from 270 to 290 and from 305 to 355 pm. The europium atoms within the distorted hexagonal channels have coordination number 14 (8 Au+6 In). EuAu3In3 shows Curie-Weiss behavior above 50 K with an experimental magnetic moment of 8.1(1) μB/Eu atom. 151Eu Mössbauer spectra show a single signal at δ=−11.31(1) mm/s, compatible with divalent europium. No magnetic ordering was detected down to 3 K. 相似文献
3.
Juan A. Colón Santana V. Singh V. Palshin E. M. Handberg A. G. Petukhov Y. B. Losovyj A. Sokolov Ihor Ketsman 《Applied Physics A: Materials Science & Processing》2010,98(4):811-819
We have characterized the local structure around the Cr atom, as a function of Cr content, in films of chromium-doped hydrogenated
amorphous diamond-like carbon (Cr-DLC) synthesized by plasma-enhanced chemical vapor deposition (PECVD). The composition appears
to be related to the structure and forward bias magnetoresistance in heterojunction devices. Chromium in diamond-like carbon
(DLC) has a chemical state much like chromium carbide and, at low Cr content, the Cr is dissolved in an amorphous DLC matrix
forming an atomic-scale composite. At higher Cr content, Cr is present as nano-composite and chromium carbide precipitates
preferentially form at the surface of the film. In these films of higher chromium concentration, a large coefficient of negative
magnetoresistance is observed in heterojunction devices with n-type silicon. 相似文献
4.
We argue that stable, maximally symmetric compactifications of string theory to 1+1 dimensions are in conflict with holography. In particular, the finite horizon entropies of the Rindler wedge in 1+1 dimensional Minkowski and anti-de Sitter space, and of the de Sitter horizon in any dimension, are inconsistent with the symmetries of these spaces. The argument parallels one made recently by the same authors, in which we demonstrated the incompatibility of the finiteness of the entropy and the symmetries of de Sitter space in any dimension. If the horizon entropy is either infinite or zero, the conflict is resolved. 相似文献
5.
Let G/K be a semisimple orbit of the adjoint representation of a real connected
reductive Lie group G. Let K1 be any closed subgroup of K containing the commutant of
the identity component of K. We prove that the geodesic flow on the symplectic manifold
T*(G/K1), corresponding to a G-invariant pseudo-Riemannian metric on G/K1 which is induced
by a bi-invariant pseudo-Riemannian metric on G, is completely integrable in the class
of real analytic functions, polynomial in momenta. To this end we study the Poisson geometry
of the space of G-invariant functions on T*(G/K) using a one-parameter family of moment
maps. 相似文献
6.
We consider several statistical models defined on the Farey fractions. Two of these models may be regarded as spin chains, with long-range interactions, while another arises in the study of multifractals associated with chaotic maps exhibiting intermittency. We prove that these models all have the same free energy. Their thermodynamic behavior is determined by the spectrum of the transfer operator (Ruelle–Perron–Frobenius operator), which is defined using the maps (presentation functions) generating the Farey tree. The spectrum of this operator was completely determined by Prellberg. It follows that these models have a second-order phase transition with a specific heat divergence of the form C [ ln2
]–1. The spin chain models are also rigorously known to have a discontinuity in the magnetization at the phase transition. 相似文献
7.
Peter Ferenc Peter Solár Ján Kleban Jaromír Mikeš Peter Fedoročko 《Journal of photochemistry and photobiology. B, Biology》2010,98(1):25-34
Presented experiment considers combination of genistein and photodynamic therapy with hypericin with a view to achieve higher therapeutic outcome in human breast adenocarcinoma cell lines MCF-7 and MDA-MB-231, both identified in our conditions as photodynamic therapy resistant. Since genistein is known to suppress Bcl-2 expression, we predicted that photodynamic therapy with hypericin might benefit from mutual therapeutic combination. In line with our expectations, combined treatment led to down-regulation of Bcl-2 and up-regulation of Bax in both cell lines as well as to suppression of Akt and Erk1/2 phosphorylation induced by photoactivated hypericin in MCF-7 cells. Although Akt and Erk1/2 phosphorylation was not stimulated by photodynamic therapy with hypericin in MDA-MB-231 cells, it was effectively suppressed in combination. Variations in cell death signaling favoring apoptosis were indeed accompanied by cell cycle arrest in G2/M-phase, activation of caspase-7, PARP cleavage and increased occurrence of cells with apoptotic morphology of nucleus. All these events corresponded with suppression of proliferation and significantly lowered clonogenic ability of treated cells. In conclusion, our results indicate that pre-treatment with tyrosine kinase inhibitor genistein may significantly improve the effectiveness of photodynamic therapy with hypericin in MCF-7 and MDA-MB-231 breast cancer cells. 相似文献
8.
9.
Dihydropalustrine has been synthesized by a β-lactam-imino ether coupling route. A dehydro precursor previously considered to represent palustrine has now been shown to be nonidentical with the natural product. 相似文献
10.
Sacková V Kuliková L Mikes J Kleban J Fedorocko P 《Photochemistry and photobiology》2005,81(6):1411-1416
The present study demonstrates the in vitro effect of hypericin-mediated PDT with fractionated light delivery. Cells were photosensitized with unequal light fractions separated by dark intervals (1 or 6 h). We compared the changes in viability, cell number, survival, apoptosis and cell cycle on HT-29 cells irradiated with a single light dose (12 J/cm(2)) to the fractionated light delivery (1 + 11 J/cm(2)) 24 and 48 h after photodynamic treatment. We found that a fractionated light regime with a longer dark period resulted in a decrease of hypericin cytotoxicity. Both cell number and survival were higher after light sensitization with a 6-h dark interval. DNA fragmentation occurred after a single light-dose application, but in contrast no apoptotic DNA formation was detected with a 6-h dark pause. After fractionation the percentage of cells in the G1 phase of the cell cycle was increased, while the proportion of cells in the G2 phase decreased as compared to a single light-dose application, i.e. both percentage of cells in the G1 and G2 phase of the cell cycle were near control levels. We presume that the longer dark interval after the irradiation of cells by first light dose makes them resistant to the effect of the second illumination. These findings confirm that the light application scheme together with other photodynamic protocol components is crucial for the photocytotoxicity of hypericin. 相似文献