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541.
Walter Simon 《General Relativity and Gravitation》2008,40(12):2591-2618
We analyze the 3-parameter family of exact, regular, static, spherically symmetric perfect fluid solutions of Einstein’s equations
(corresponding to a 2-parameter family of equations of state) due to Pant and Sah and “rediscovered” by Rosquist and by the
present author. Except for the Buchdahl solutions which are contained as a limiting case, the fluids have finite radius and
are physically realistic for suitable parameter ranges. The equations of state can be characterized geometrically by the property
that the 3-metric on the static slices, rescaled conformally with the fourth power of any linear function of the norm of the
static Killing vector, has constant scalar curvature. This local property does not require spherical symmetry; in fact it
simplifies the proof of spherical symmetry of asymptotically flat solutions which we recall here for the Pant-Sah equations
of state. We also consider a model in Newtonian theory with analogous geometric and physical properties, together with a proof
of spherical symmetry of the asymptotically flat solutions.
Supported by grants FIS2006-05319 (Ministerio de Educación y Tecnología) and SA010C0 (Junta de Castillia y León). 相似文献
542.
微区Raman光谱在TiO_2高压结构相变研究中的应用 总被引:1,自引:1,他引:0
本文以金红石单晶TiO2和锐钛矿多晶TiO2为研究对象,应用金刚石小压机和原位拉曼光谱测量技术,系统研究了室温高压下TiO2的结构相变。原位拉曼测量表明,金红石单晶TiO2在压力达到12.91GPa时开始发生由金红石结构向斜锆石结构(MI)的相变,当压力达到14.16 GPa时,相变完成;继续加压到21.65 GPa,没有发现进一步的相变;卸压时由斜锆石结构转变为PbO2结构,相变发生在大约7.11 GPa处。锐钛矿多晶TiO2在压力达到4.26 GPa时开始向PbO2结构转变,当压力达到8.34 GPa时相变完成;继续加压到12.94 GPa,样品开始发生由PbO2结构向斜锆石结构的相变,当压力达到18.74 GPa时相变完成;继续加压到21.39 GPa,没有发现进一步的相变;卸压时也由斜锆石结构转变为PbO2结构,起始相变压力点应高于8 GPa。 相似文献
543.
Molecular ion yield enhancement induced by gold deposition in static secondary ion mass spectrometry
Static ToF-SIMS was used to evaluate the effect of gold condensation as a sample treatment prior to analysis. The experiments were carried out with a model molecular layer (Triacontane M = 422.4 Da), upon atomic (In+) and polyatomic (Bi3+) projectile bombardment. The results indicate that the effect of molecular ion yield improvement using gold metallization exists only under atomic projectile impact. While the quasi-molecular ion (M+Au)+ signal can become two orders of magnitude larger than that of the deprotonated molecular ion from the pristine sample under In+ bombardment, it barely reaches the initial intensity of (M−H)+ when Bi3+ projectiles are used. The differences observed for mono- and polyatomic primary ion bombardment might be explained by differences in near-surface energy deposition, which influences the sputtering and ionization processes. 相似文献
544.
Faouzi Triki & Tao Yin 《计算数学(英文版)》2023,41(3):482-500
This paper concerns the reconstruction of a scalar coefficient of a second-order elliptic equation in divergence form posed on a bounded domain from internal data. This problem finds applications in multi-wave imaging, greedy methods to approximate parameter-dependent elliptic problems, and image treatment with partial differential equations. We first show that the inverse problem for smooth coefficients can be rewritten as a linear transport equation. Assuming that the coefficient is known near the boundary, we study the well-posedness of associated transport equation as well as its numerical resolution using discontinuous Galerkin method. We propose a regularized transport equation that allow us to derive rigorous convergence rates of the numerical method in terms of the order of the polynomial approximation as well as the regularization parameter. We finally provide numerical examples for the inversion assuming a lower regularity of the coefficient, and using synthetic data. 相似文献
545.
Fan Chen Dr. Baoxin Zhang Dr. Zhenjiang Ding Miao Zhong Dr. Yanan Hou Fang Zhang Dr. Guodong Hu Prof. Jianguo Fang 《Angewandte Chemie (International ed. in English)》2023,62(21):e202301598
The development of small-molecule probes suitable for live-cell applications remains challenging yet highly desirable. We report the first fluorescent probe, RBH, for imaging the heme oxygenase-1 (HO-1) activity in live cells after discovering hemin as a universal dark quencher. Hemin works via a static quenching mechanism and shows high quenching efficiency (>97 %) with fluorophores across a broad spectrum (λex=400–700 nm). The favorable properties of RBH (e.g. long excitation/emission wavelengths, fast response rate and high magnitude of signal increase) enable its use for determining HO-1 activity in complex biological samples. As HO-1 is involved in regulating antioxidant defence, iron homeostasis and gasotransmitter carbon monoxide production, we expect RBH to be a powerful tool for dissecting its functions. Also, the discovery of hemin as a general static dark quencher provides a straightforward strategy for constructing novel fluorescent probes for diverse biological species. 相似文献