相匹配契伦可夫辐射式倍频

用波导产生倍频波时,如果倍频波进入辐射模区,仍然有相匹配问题。契伦可夫辐射式倍频不是自动地实现相匹配的。相匹配要求导波基波模式场,倍频传输场(自由波),倍频触发场,以及经多次反射透射后的辐射场的迭加形成的总辐射场处于同步的相匹配状态。根据这个相匹配的分析,提出波导契伦可夫相匹配的特有的方法,那就是对波导的模色散进行设计,并指出非对称波导的特有优点,是改变一个边界上的反射相变,即选择不同色散的线性材料作包层,由此可得到相匹配的高效契伦可夫倍频辐射。     

Formation of a two-dimensional periodic structure of local melting regions on a silicon surface upon pulsed light irradiation

The first results regarding the formation of a two-dimensional periodic structure of local melting regions on a silicon surface upon pulsed light irradiation are presented. The conditions are established, and the mechanism of the formation of such structures is discussed. Zh. Tekh. Fiz. 67, 97–99 (December 1997)     

5-[5-R-furfurylidene]-2,2-dimethyl-1,3-dioxane-4,6-diones 5. Nucleophilic replacement of halogen in the furan ring

Halogen in positions 3 and 5 of the furan ring in ftirfurylidenedioxanediones is readily replaced by dithiocarbonate, dithiocarbatnate, dithiophosphate, thiocyanate, and azide anions, and by thiourea, and secondary and tertiary amines. The conformation of the initial halogen derivative is retained in the substitution products.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 327–334, March, 1994.     

Mass spectra of pseudoguaianolides related to carpesiolin

The main directions of fragmentation and the EI of six pseudoguaianolides related to carpesiolin have been studied. It has been established that acylation of the OH group at C-6 suppresses the selective breakdown of the guaiane skeleton, while the simultaneous presence of AcO groups at C-2 and C-4 favors the formation of a number of characteristic ions. The hydrogenation of the exomethylene group has no appreciable influence on direction of fragmentation.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 530–535, July–August, 1993.     

Isolation of phospholipase A2 from the venom of the green toadBufo viridis

Phospholipase A₂ has been isolated fromthe venom of he Central Asian green toad Bufo viridis in the electroophoretically homogeneous state for the first time by biospecific absorption chromatography. The affinity sorbent used was Affi-Gel 10 with covalently bound phosphatidylserine (PDS). The chemical inertness of the bound PDS to the hydrolytic action of phospholipase A2 and its high tendency to form biospecific complexes have been shown. Some biochemical characteristics of the enzyme isolated have been studied: influence of the pH and of the Ca²⁺ concentration and dependence of activity on substrate concentration.A. S. Sadykov Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax 627071. Tashkent State University, fax 462472. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 105–109, January–February, 1994.     

Stress–Strain Analysis of Rectangular Plates with a Variable Thickness and Constant Weight

The stress–strain state of rectangular plates with a variable thickness and constant weight is analyzed. The laws of variation in the thickness are specified to depend on parameters so that the plate weight remains constant for any of their values. To solve the problem, discrete Fourier series are used, which makes it possible to reduce a two-dimensional problem to one-dimensional. Calculation results are presented.     

SU(2)×SU(2)准自旋模型和自洽解的对称性恢复方法——Ⅰ.严格解和HF近似

本文提出了一个含有两类相互作用的准自旋模型,讨论了模型Hamilton量在SU(2)×SU(2)基中的严格解、基态相变和波函数的K结构,并用此模型探讨了HF近似的有效性。     

On construction of symmetries from integrals of hyperbolic partial differential systems

An algorithm is proposed which allows one to construct higher symmetries of arbitrary order for some special classes of hyperbolic systems possessing integrals. The Pohlmeyer-Lund-Regge system and the open two-dimensional Toda lattices are shown to belong to the class of systems where our algorithm is applicable. __________ Translated from Fundamental’naya i Prikladnaya Matematika (Fundamental and Applied Mathematics), Vol. 10, No. 1, Geometry of Integrable Models, 2004.