NR activity in the accelerating cavities development and study for ILC positron source parameters

The critical part of the normal conducting (NC) positron preaccelerator (PPA) at the ILC positron source (PS) are capture sections that should operate with an accelerating gradient of up to 15 MV/m in combination with long RF pulse (∼1 ms). Developed at the Institute of Nuclear Research (INR) and now being constructed at DESY, the CDS booster cavity for the Photo Injector Test facility, DESY, Zeuthen, will operate under the same conditions and is a full-scale, high-RF-power prototype of the PS capture cavities. Cavity construction status and results of cavity tuning at a low RF level are presented. Other features of the standing wave cavities for the PPA, such as RF pulsed heating, advanced cooling, and beam loading, are discussed. The text was submitted by the authors in English.     

Crown-containing styryl derivatives of naphthopyrans: Complexation with alkaline-earth metal cations and photochemistry

The photochemistry and complexation with alkaline-earth metal cations of two crown-containing naphthopyrans and their crownless analogues are reported. Two types of photoreactions occur in the system, namely, the reversible formation of the open form, which is responsible for the photochromism of these compounds, and the geometric isomerization of the closed form. The photochromic properties (UV spectrum and lifetime) of the naphthopyrans do not change upon complexation with metal cations. This is explained by the specific features of the structure of the open form and by the kinetic parameters of the processes.     

Ferromagnetism, paramagnetism, and thermally induced magnetism in photomagnetic CrIII/MnII and CrIII oxalates with the 7-methyl-3,3-diphenyl-3H-pyrano[3,2-f]quinolinium cation

Single crystals of the new cationic chromene, 7-methyl-3,3-diphenyl-3H-pyrano[3,2-f-quinolinium iodide (C₂₅H₂₀NO)I (1), were synthesized. The crystal structure of the new compound was studied, and quantum chemical calculation for the open and closed forms were carried out. The bifunctional compounds containing mono- and bimetallic 3d metal (tris)oxalates with the chromenium cation, (C₂₅H₂₀NO)₃[Cr(C₂O₄)₃] · 4H₂O (2) and (C₂₅H₂₀NO)[CrMn(C₂O₄)₃] · H₂O (3), were prepared. Compound 1 is paramagnetic due to low-lying thermally excited states of the chromene molecules. At low temperatures (∼2 K), the paramagnetic states are frozen, and the compound becomes diamagnetic. Compound 2 is paramagnetic and its magnetic properties are determined mainly by the Cr³⁺ ions and the thermally induced paramagnetic states of the chromene molecules. At high temperatures, the magnetic moment of compound 3 consists of the contributions of the paramagnetic Cr³⁺ and Mn²⁺ ions and the thermally induced paramagnetic states of chromenes. At low temperatures (2–3 K), the thermally induced magnetism of organic molecules is frozen, and the magnetically ordered (and, probably, spin-glass) state is observed in the two-dimensional network of metal oxalates (T _c = 3 K in the zero magnetic field). The UV irradiation leads to an increase in the magnetic moment of the compound in the paramagnetic region due to the generation of radiation defects.     

Raman fiber laser for the drug-free photodynamic therapy

An SRS laser with a radiation wavelength of 1.262 μm and a maximum power of 5.5 W is presented. The laser wavelength corresponds to the excitation band of singlet oxygen and can be used for the treatment of oncological diseases. The laser source is employed for the treatment of basalioma.     

High quality beam shaping by square soft-edge diaphragm combined with liquid crystal spatial light modulator

<正>The square soft-edge diaphragm with round angle is designed by Matlab,and is sent to a liquid crystal spatial light modulator by the computer.In order to obtain precompensation for the following laser system, local diaphragm transmission can be adjusted by feedback signals of surface-channel charge-coupled device (SCCD).This method can reduce the diffraction effect and realize no modulation,high stability,high homogeneity,and large scale laser beam.Several parameters of soft-edge diaphragms which affect the laser beam quality are studied systematically,and the optimized values are obtained.The method can avoid the serious modulation of hard edges and provide soft-edge diaphragms of different shapes in a fast and convenient way for the large scale laser beam system.     

Alk-2-yn-1-amines in the synthesis of substituted quinolines in the presence of palladium complexes

An effective one-step procedure has been developed for the synthesis of 4- and 2,3,4-substituted quinolines via reaction of o-iodoaniline with alk-2-yn-1-amines in the presence of Pd(OAc)₂ as catalyst.     

Absorption spectra of photoinduced E isomers of aurones,thioindogenides, and selenoindogenides

Theoretical and Experimental Chemistry -     

A Probabilistic Model of the Fatigue Life of Composite Materials for Fatigue-Curve Approximations

A simple mathematical model for the fatigue life of composite materials in which the basic load is taken up by parallel rigid components (fiber strands) is offered. Based on the Markov chain theory, the model allows us to obtain an S-type curve for the growth of internal stresses and to calculate the relationship between the parameters of static strength distribution and the S-N fatigue curve (Wholer curve). The model is too simple and does not provide a numerical coincidence with experimental fatigue-test data, but, when used with additional parameters, it agrees with experiments and can be applied to the model of nonlinear regression in describing the fatigue curve and its variation as the parameters of static strength change.     

Synthesis,metal ion binding,and photochromic properties of benzo- and naphthopyrans annelated by crown ether moieties

Combining a photochromic chromene with a crown ether moiety results in systems in which photochromism and ionophoric properties could significantly influence each other. In this paper, we report the synthesis of several chromenes annelated by 15(18)-crown-5(6) ethers. The approach involves the building of the photochromic fragment upon the initial crown ether via phenols. The two main routes for chromene preparation are discussed. The complex formation of the synthesized photochromic crown-containing naphthopyran with magnesium(II) and barium(II) cations was studied. The kinetic behavior of the colored form of the compound is affected by complex formation.