Multicriteria Optimal Design of a Rectangular Composite Plate Subjected to Biaxial and Thermal Loading

Multicriteria optimization of the structure and geometry of a laminated anisotropic composite plate subjected to the thermal and biaxial action is considered. From known properties of the monolayer and the given values of variable structural parameters, the thermoelastic properties of the layered composite are determined. The criteria to be optimized—the transverse critical load and the longitudinal thermal stresses—depend on two variable design parameters of composite properties and temperature. In the space of the optimization criteria, the domain of allowable solutions and the Pareto-optimal subdomain are found. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 5, pp. 683–690, September–October, 2005.     

Gauge Dependence of the Effective Gravitational Field

We analyze the gauge ambiguity problem for the effective gravitational field from the standpoint of the measurement process. The motion of a test point particle playing the role of a measuring device is investigated in the field of a point gravitating mass in the one-loop approximation. We show that the gravitational field value determined from the effective equations of motion of the device explicitly depends on the Feynman gauge parameter. This dependence is essential in the sense that a gauge variation cannot be interpreted as a deformation of the reference frame, which leads to a gauge ambiguity in the values of observed quantities. In particular, this result disproves the hypothesis that gauge dependence is canceled in the effective equations of motion of a classical point particle.     

Spectroscopic analysis of Er transition in Mg/Er-codoped LiNbO3 crystal

We present a Judd-Ofelt spectroscopic analysis on the Mg/Er-codoped congruent lithium niobate (LiNbO₃) crystals. The Judd-Ofelt model is applied to the room temperature unpolarized absorption intensities of Er³⁺ ions on eleven transition bands to determine their intensity parameters: Ω₂=2.36×10⁻²⁰ cm², Ω₄=0.76×10⁻²⁰ cm², Ω₆=0.30×10⁻²⁰ cm² in Er:LiNbO₃ crystal heavily codoped with MgO. The radiative lifetime of ²H_9/2 becomes longer when MgO is added into Er:LiNbO₃ crystal. The experimental lifetimes are obtained using microsecond time-resolved spectra at 400 nm femtosecond pulse excitation to predict radiative quantum efficiency. Combining higher radiative quantum efficiency with longer radiative lifetime, we conclude that Mg/Er-codoped LiNbO₃ crystals are more suitable than Er: LiNbO₃ ones in laser materials.     

广义脉冲谱方法的一个新形式及其应用

构造了一种新的、有一定抗噪能力的广义脉冲谱方法(GPST)的计算格式。设计了选取正则参数过程中节省计算量的技巧.最后探讨了方法在地震勘探一维波方程反问题上的应用,进行了数值模拟。     

全纯扩充的BHW定理的推广

本文得到关于全纯扩充的BHW定理的一个全新的证明,同时也对BHW定 理做出了更一般的推广,并且给出了推广后的BHW定理的两种不同的证明方法.     

Stability of Rotation Relations of Three Unitaries with the Flip Action in C*-Algebras*

The authors show that if Θ = (θ_jk) is a 3 × 3 totally irrational real skewsymmetric matrix, where θ_jk ∈ [0, 1) for j, k = 1, 2, 3, then for any ε > 0, there exists δ > 0 satisfying the following: For any unital C^*-algebra A with the cancellation property,strict comparison and nonempty tracial state space, any four unitaries u₁, u₂, u₃, w ∈ A such that (1) u_ku_j - e^{2πiθjk ujukk} < δ, wu_jw^-1 = u^-1_j, w² = 1_A for j, k = 1, 2, 3; (2)τ (aw) = 0 and τ ((u_ku_ju_k^*u_j^* )ⁿ ) = e^2πinθjk for all n ∈ N, all a ∈ C^*(u₁, u₂, u₃), j, k = 1, 2, 3 and all tracial states τ on A, where C^*(u₁, u₂, u₃) is the C^*-subalgebra generated by u₁, u₂ and u₃, there exists a 4-tuple of unitaries u₁, u₂, u₃, w in A such that u_ku_j = e^2πinθjk u_ku_j, w u_j w^-1 = u^-1 _j, w² = 1A and k u_j - u_jk < ε, k w - wk < ε for j, k = 1, 2, 3. The above conclusion is also called that the rotation relations of three unitaries with the flip action is stable under the above conditions.     

电磁波在左右手介质界面折射与反射特性的研究

研究了电磁波在左右手介质界面折射与反射的特性,给出了折射系数和反射系数,从另外一个方面探讨了最小作用量原理在左手材料中的适用性;从电动力学和最小作用量原理证明了Snell定律,验证了Snell定律在左手材料中的适用性,并且得到Fresnell公式在左右手材料中的一致性.     

The role of C-centered radicals on the mechanism of action of artemisinin

Artemisinin is a sesquiterpene lactone with an endoperoxide function that is essential for its antimalarial activity. Endoperoxides are supposed to act on heme leading to the reduction of the peroxide bond and production of radicals, which can be responsible for killing the parasite. The geometries of artemisinin, radical anions and neutral species generated by rearrangement after reduction of the peroxide bond were fully optimized with the AM1 and PM3 semi-empirical methods, in order to characterize the intermediates formed during the process. Among the radicals calculated along the pathway for reductive decomposition of artemisinin, the secondary radical centered on carbon C₄ has the highest stability when compared to other radicals that can be achieved either by hydrogen migration to the original O-centered radical or by homolytic break of C–C bond. This suggests that the C₄-centered radical may be the species responsible for killing the parasite, as has been indicated previously in experimental studies.     

A new fluorescent sensor selective for Pb<Superscript>2+</Superscript> in water capable of two-photon-induced fluorescence measurement

A new fluorescent sensor (1) for Pb²⁺ containing a 1,4-dicyano-2,5-bis(styryl)benzene fluorophore and 2-(N,N′-bis(carboxylmethyl))amino-1-carboxylmethoxylbenzene as receptor has been synthesized. The sensor selectively responds to Pb²⁺ in the aqueous environment, and brings about similar and significant changes in one- and two-photon excited emission spectra: λ _max red-shift from 460 (519) to 590 nm. The selective response is pH-independent in a large physiological pH range, and two-photon action cross section (ϕδ) is 51 GM (1 GM = 1×10⁻⁵⁰ cm⁴·s·photon⁻¹·molecule⁻¹) at 740 nm. Supported by the National Natural Science Foundation of China (Grant Nos. 20705621 & 20706008), the National Basic Research Project of China (Grant No. 2009CB724706), the Ministry of Education of China, Changjiang Scholars Innovative Research Team in University (Grant No. IRT0711) and Cultivation Fund of the Key Scientific and Technical Innovation Project (Grant No. 707016)     

Thermal and Spectral Behaviour of 5-chloro-2-methoxybenzoates of Heavy Lanthanides and Yttrium

5-Chloro-2-methoxybenzoates of heavy lanthanides and yttrium were obtained as di- or tetrahydrates with a metal to ligand ratio of 1:3 and general formula: Ln(C₈H₆ClO₃)₃⋅nH₂O, where n=2 for Ln=Tb, Dy, Y and n=4 for Ln=Ho, Er, Tm, Yb, Lu. The complexes were characterized by elemental analysis, IR and FIR spectra, thermogravimetric studies, X-ray diffraction and magnetic measurements. The carboxylate group appears to be a symmetrical, bidentate, chelating ligand. All complexes are polycrystalline compounds. Their thermal stabilities were determined in air and in nitrogen atmospheres. When heated they dehydrate to form anhydrous salts which next in air are decomposed to the oxides of the respective metals while in nitrogen to the mixtures of carbon and oxides or carbon and oxychlorides of respective metals. The complexes are more stable in air than in nitrogen. The solubilities of yttrium and heavy lanthanide 5-chloro-2-methoxybenzoates in water at 293 K are of the order of 10^–3 mol dm^–3 The magnetic moments of the complexes were determined over the range 77–298 K. They obey the Curie–Weiss law. The values of μ_eff calculated for all compounds are close to those obtained for Ln³⁺ by Hund and Van Vleck. The results indicate that there is no influence of the ligand field of 4f electrons on lanthanide ions and the metal ligand bonding is mainly electrostatic in nature. This revised version was published online in August 2006 with corrections to the Cover Date.