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1.
2.
Raz Kupferman 《Journal of statistical physics》2004,114(1-2):291-326
We study a variant of the Kac–Zwanzig model of a particle in a heat bath. The heat bath consists of n particles which interact with a distinguished particle via springs and have random initial data. As n → ∞ the trajectories of the distinguished particle weakly converge to the solution of a stochastic integro-differential equation—a generalized Langevin equation (GLE) with power-law memory kernel and driven by 1/f α -noise. The limiting process exhibits fractional sub-diffusive behaviour. We further consider the approximation of non-Markovian processes by higher-dimensional Markovian processes via the introduction of auxiliary variables and use this method to approximate the limiting GLE. In contrast, we show the inadequacy of a so-called fractional Fokker–Planck equation in the present context. All results are supported by direct numerical experiments. 相似文献
3.
Rachel Atzmon Ori Cheshnovsky Baruch Raz Joshua Jortner 《Chemical physics letters》1974,29(3):310-313
We report an experimental study of Xe(3P1) → Xe(3P2) electronic quenching by Ar in Xe/Ar mixtures optically excited by the 1470 Å line of Xe. The quenching process was monitored by the observation of the Xe*2 second emission continuum at low Xe pressures. 相似文献
4.
In this paper we report the results of an experimental study of the vacuum ultraviolet absorption spectra of molecular impurity states of methyl iodide in Ar (density range ? = 0–1.4 g cm?3) and in Kr (? = 0–2.3 g cm?3), of carbon disulphide in Ar (? = 0–1.4 g cm?3) and of formaldehyde in Ar (? = 0–1.25 g cm?3). The experimental results provide new information regarding medium perturbations of intravalenc transitions, of the lowest extravalence transitions and of transitions to mixed valence—Rydberg configurations, which serve as a diagnostic tool to distinguish between different types of electronic excitations. All the lowest extravalence molecular excitations exhibit appreciable blue spectral shifts at moderate and at high fluid densities, intravalence transitions are practically insensitive to medium effects, while excitations to mixed valence—Rydberg configurations are characterized by a moderate blue spectral shift. New information has been obtained concerning the energetics of molecular ionization processes in a dense fluid. The high n = 2–5 Rydberg states of CH3l exhibit a large red shift at moderate (? = 0–0.5 cm?3) Ar densities. The ionization potential Eg and the effective Rydberg constant G for CH3I in Ar was found to decrease from G = 13.6 eV and Eg = 9.55 eV at ? = 0 and Eg = 9.08 eV and constant G for CH3l in Ar was found to decrease from G = 13.6 eV and Eg = 9.55eV at ? = 0 and Eg = 9.08 eV and G ≈ 7.15 eV at ? = 0.5 g cm?3. Experimental evidence was obtained for the identification of n = 2 molecular Wannier impurity states of CH3I and of CH2O in liquid Ar. These spectroscopic data result in Eg ≈ 8.6 eV for CH3I in liquid Ar and Eg ≈ 10.2 eV for CH2O in liquid Ar. 相似文献
5.
B. Jelinek E. A. Schmidt J. Tikka J. Itkonen Elisabeth Tornow Bernadine Brimhall R. M. Hixon H. H. Bagnall R. S. Potter J. K. Fleming J. Tillmans R. Strohecker und O. Heublein 《Fresenius' Journal of Analytical Chemistry》1940,119(7-8):300-302
Ohne Zusammenfassung 相似文献
6.
J. Hladik R. Müller G. Giuliani R. Riparbelli E. F. Posorski K. Mohs H. Schmalfuß H. Werner W. Stoldt W. Hofmann Ch. Matejovský E. A. Schmidt J. Großfeld K. Schwarz H. Jesser R. Maina M. Henzi B. Jelinek R. M. Sandstedt F. C. Hildebrand B. A. McClellan M. J. Blish W. F. Geddes F. H. Lehberg und C. Enders 《Fresenius' Journal of Analytical Chemistry》1939,118(1-2):34-41
Ohne Zusammenfassung 相似文献
7.
Dr. Umesh A. Kshirsagar Regev Parnes Hagit Goldshtein Dr. Rivka Ofir Dr. Raz Zarivach Dr. Doron Pappo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13575-13583
An iron‐based cross‐dehydrogenative coupling (CDC) approach was applied for the diversity‐oriented synthesis of coumestrol‐based selective estrogen receptor modulators (SERMs), representing the first application of CDC chemistry in natural product synthesis. The first stage of the two‐step synthesis of coumestrol involved a modified aerobic oxidative cross‐coupling between ethyl 2‐(2,4‐dimethoxybenzoyl)acetate and 3‐methoxyphenol, with FeCl3 (10 mol %) as the catalyst. The benzofuran coupling product was then subjected to sequential deprotection and lactonization steps, affording the natural product in 59 % overall yield. Based on this new methodology other coumestrol analogues were prepared, and their effects on the proliferation of the estrogen receptor (ER)‐dependent MCF‐7 and of the ER‐independent MDA‐MB‐231 breast cancer cells were tested. As a result, new types of estrogen receptor ligands having an acetamide group instead of the 9‐hydroxyl group of coumestrol were discovered. Both 9‐acetamido‐coumestrol and 8‐acetamidocoumestrol were found more active than the natural product against estrogen‐dependent MCF‐7 breast cancer cells, with IC50 values of 30 and 9 nM , respectively. 相似文献
8.
Z. Teuberova M. Seydlova T. Dostalova B. Dvorankova K. SmetanaJr. M. Jelinek P. Masinova T. Kocourek K. Kolarova J. Wilson 《Laser Physics》2007,17(1):45-49
Coating dental implants with hydroxyapatite (HA) may give certain advantages such as active encouragement of new bone growth, a lower rejection rate, and an improved long-term prosthesis fixation. This study examined the mechanical and biological properties of titanium alloy implant cores with an interlayer of zirconia and a coating of HA created using pulsed Laser deposition (PLD). The thickness of the zirconia layer was 50–100 nm, and the HA layer was ~600 nm. The crystallinity, morphology, wettability, and Ca/P ratio of the HA layer were investigated by electron microscopy, X-ray diffraction, goniometric measurement of contact angle, and wavelength dispersive X-ray analysis. The physical tests indicated adequate mechanical properties and a satisfactory adhesion to a titanium core modified with zirconia and HA. Cell proliferation and metabolic activity of human embryonal lung fibroblasts were determined using counting of harvested cells and providing an MTT assay. it was demonstrated that none of the samples were cytotoxic and their surfaces promoted cell colonization. PLD was found to be a promising method of applying coatings to a metal core for dental implants, and the in vitro biological tests suggest that the crystalline HA coating can improve the biological properties of titanium covered with zirconia. 相似文献
9.
Mariana Pokrass Doron Azulay Isaac Balberg Nurit Atar Raz Gvishi Menachem Nathan 《Journal of Sol-Gel Science and Technology》2014,70(3):517-527
Electrical properties of multi-walled carbon nanotubes (MWNTs)/hybrid-glass nanocomposites prepared by the fast-sol–gel reaction were investigated in light of percolation theory. A good correlation was found between the experimental results and the theory. We obtained a percolation threshold ? c = 0.22 wt%, and a critical exponent of t = 1.73. These values are reported for the first time for a silica-based system. The highest conductivity measured on the MWNT/hybrid-glass nanocomposites was σ ≈ 10?3(Ω cm)?1 for 2 wt% carbon nanotube (CNT) loading. The electrical conductivity was at least 12 orders of magnitude higher than that of pure silica. Electrostatic force microscopy and conductive-mode atomic force microscopy studies demonstrated conductivity at the micro-level, which was attributed to the CNT dispersed in the matrix. It appears that the dispersion in our MWNT/hybrid-glass system yields a particularly low percolation threshold compared with that of a MWNT/silica-glass system. Materials with electrical conductivities described in this work can be exploited for anti-static coating. 相似文献
10.
Jan Remsa Miroslav Jelinek Tomáš Kocourek Ji?í Oswald Marian ?erňanský Michal Jelínek 《Applied Surface Science》2009,255(10):5292-5294
High quality, thick, highly oriented crystalline thin films of Yttrium Aluminum Garnet (Y3Al5O12) and Yttrium Aluminum Perovskite (YAlO3) doped with Erbium were prepared by pulsed laser deposition. Samples were created in vacuum or oxygen environment. Depositions were arranged at room temperature, or at high substrate temperatures ranging from 800 to 1100 °C. Amorphous layers were annealed by laser, or in oven (argon flow, temperatures in range from 1200 to 1400 °C). Fused silica and sapphire (0 0 0 1) were used as substrates. Properties of films were characterized by X-ray diffraction, atomic force microscopy, and by photoluminescence measurement. Size of crystalline grains was in the range 116-773 nm. Thickness of layers was up to 17 μm. 相似文献