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961.
D. V. Novikov G. K. Elyashevich V. K. Lavrentyev I. S. Kuryndin V. Bukošek 《Physics of the Solid State》2013,55(9):1968-1975
The effect of the annealing temperature T ann of extruded polypropylene films on the structure of membranes prepared by the uniaxial extension of annealed films with the subsequent thermal fixation has been investigated using small-angle X-ray scattering and scanning electron microscopy. It has been shown that an increase in the permeability of membranes with increasing temperature T ann is due to the self-organization of elements of the lamellar structure of the polymer as a result of the ordering and aggregation of particles. 相似文献
962.
963.
964.
Laura Äkäslompolo Ana M. Sánchez Qi Hang Qin Antti Hakola Timo Kajava Sebastiaan van Dijken 《Applied Physics A: Materials Science & Processing》2013,110(4):889-894
We report on the growth of all-oxide SrRuO3/CoFe2O4/La2/3Sr1/3MnO3 and La2/3Sr1/3MnO3/CoFe2O4/SrRuO3 heterostuctures on SrTiO3(001) and MgO(001) substrates by pulsed laser deposition. Structural analyses by X-ray diffraction and transmission electron microscopy clearly indicate the preservation of epitaxial relations when the La2/3Sr1/3MnO3 layer is grown first, whereas trilayers with SrRuO3 at the bottom are more disordered. Both the substrate material and the deposition sequence strongly influence the formation of various structural defects such as interfacial dislocations and sub-grain structures, and this is clearly reflected by a reduction of the saturation magnetization in the top electrode. When the substrate material and the deposition sequence are correctly chosen, however, the magnetic moments of the La2/3Sr1/3MnO3 and SrRuO3 layers reverse independently, and the La2/3Sr1/3MnO3 layer retains bulk-like magnetic properties. 相似文献
965.
G. Machinet G. Andriukaitis P. Sévillano J. Lhermite D. Descamps A. Pugžlys A. Baltuška E. Cormier 《Applied physics. B, Lasers and optics》2013,111(3):495-500
We report on high single-pass gain in Yb:CaF2 crystal longitudinally pumped with a 40 W high-brightness fiber laser source based on an ytterbium-doped ultra-large core photonic crystal rod-type fiber operating at 976 nm. A single-pass small-signal gain of 3.2 has been achieved in a 6 % Yb-doped 10-mm-long CaF2 crystal at room temperature, outperforming any CW-diode-pumped scheme and paving the way towards very promising innovative lasers and amplifiers schemes merging the Yb-doped solid-state and fiber technologies. 相似文献
966.
Brandon J. O'Neill David H. K. Jackson Dr. Anthony J. Crisci Carrie A. Farberow Fengyuan Shi Dr. Ana C. Alba‐Rubio Dr. Junling Lu Dr. Paul J. Dietrich Dr. Xiangkui Gu Dr. Christopher L. Marshall Prof. Peter C. Stair Dr. Jeffrey W. Elam Dr. Jeffrey T. Miller Prof. Fabio H. Ribeiro Prof. Paul M. Voyles Prof. Jeffrey Greeley Prof. Manos Mavrikakis Prof. Susannah L. Scott Prof. Thomas F. Kuech Prof. James A. Dumesic 《Angewandte Chemie (International ed. in English)》2013,52(51):13824-13824
967.
Joana Lia Ferreira Maria João Melo Ana Maria Ramos 《Polymer Degradation and Stability》2010,95(4):453-461
The photochemistry of poly(vinyl acetate), PVAc, homopolymer, of PVAc mixtures with selected pigments and fillers, and of accurate historic reproductions based on the colours prepared by Portuguese artist Joaquim Rodrigo and on those supplied by the company A Favrel was studied. The systems, applied as films, were irradiated at λ ≥ 300 nm and the changes followed by size exclusion chromatography, infrared spectroscopy, and colorimetry.PVAc as homopolymer or as an emulsion paint proved to be very stable to light, and after 5000 h of irradiation no gel fraction was observed. ΦR (λirr = 313 nm) for chain scission for PVAc was determined to be 7 × 10−8. This value indicates that the mechanism/s operating when irradiating at λ ≥ 300 nm are different from those previously published with irradiation involving 254 nm. No side-group scission was observed, and main chain scission is the foremost photodegradation mechanism. Also, the metal ions present in the pigments do not affect the photochemical stability of the polymer. 相似文献
968.
A. Aleškevičienė 《Lithuanian Mathematical Journal》2010,50(1):1-12
In this paper, we consider the Sparre Andersen insurance risk model with initial surplus x > 0. Let Ax denote the deficit at the time of ruin. Assuming that the tail probabilities of claim size are regularly varying, the second-order
asymptotic of the deficit distribution and its moments at the time of ruin are derived. 相似文献
969.
In this paper, we prove that all manifolds with affine or projective connection are globally projectively equivalent to some
manifolds with equiaffine connection (equiaffine manifold). 相似文献
970.
Ahmed Al‐Harrasi Dr. Fabian Pfrengle Dipl.‐Chem. Vladimir Prisyazhnyuk Dr. Shahla Yekta Dr. Peter Koóš Dr. Hans‐Ulrich Reissig Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(43):11632-11641
1,3‐Dioxolanyl‐substituted 1,2‐oxazines, such as syn‐ 1 and anti‐ 1 , rearrange under Lewis acidic conditions to provide bicyclic products 2 – 5 . Subsequent reductive transformations afforded enantiopure 3‐aminopyran derivatives such as 7 and 9 or their protected diastereomers 16 and 18 , which can be regarded as carbohydrate mimetics. An alternative sequence of transformations including selective oxidation of the primary hydroxyl groups in 21 and 24 led to two protected β‐amino acid derivatives with carbohydrate‐like backbone (sugar amino acids). Treatment of bicyclic ester 23 with samarium diiodide cleaved the N? O bond and furnished the unusual β‐lactam 27 in excellent yield. Alternatively, γ‐amino acid derivative 29 was efficiently prepared in a few steps. Fairly simple transformations gave azides 32 and 35 or alkyne 30 which are suitable substrates for the construction of oligosaccharide mimetics such as 34 by copper iodide catalyzed cycloadditions. With this report we demonstrate that enantiopure rearrangement products 2 – 5 are protected precursors of a variety of polyfunctionalized pyran derivatives with great potential for chemical biology. 相似文献