A gamma-ray signature of energetic sources of cosmic-ray nuclei

Astrophysical sources of nuclei are expected to produce a broad spectrum of isotopes, many of which are unstable. An unstable nucleus can beta-decay outside the source into a single-electron ion. Heavy one-electron ions, thus formed, can be excited in their interactions with cosmic microwave background photons, in which case they relax to the ground state with the emission of a gamma ray. Repetitive cycles of excitation and gamma-ray emission can produce an observable feature in the gamma-ray spectrum with a maximum around 8 GeV (for iron). We find that the observed spectrum of Centaurus A is consistent with a substantial flux of nuclei accelerated to 0.1 EeV. A characteristic 5-10 GeV (iron) shoulder in the gamma-ray spectra of various sources can help identify astrophysical accelerators of nuclei or set upper limits on nuclear acceleration.     

Recombination Chemiluminescence in Photoirradiation of Epoxy Acrylate Polymer Compositions and Its Use for Monitoring of the Network Structure Development

Photoinduced recombination chemiluminescence was applied for monitoring of the network structure formation under UV exposure of films prepared by esterification with acrylic acid of oligomers such as UP-612, ED-16, and Oksilin commercial epoxy resins. The chemiluminescence decay was described in terms of the fractal kinetics model. The spectral dimension parameter, apparent luminescence activation energies, and glass transition temperatures of the polymers were calculated.     

Relaxation Kinetics of the Microhardness of KDP Crystals after Their Exposure to a Magnetic Field

It has been shown that potassium dihydrogen phosphate crystals change their microhardness reversibly after their exposure to a magnetic field of B = 0.8 or 1.2 T for t_m = 7–90 min. It has been found that the magnetic effect can be conveniently characterized by the quantity B²t_m, because the variation of the parameters conserving B²t_m=const does not change the result. At B²t_m < 10 T² min, the effect is almost absent. Above this threshold, the amplitude of changes in the microhardness increases and approaches a constant value of ~10% at B²t_m ≈ 19 T² min. The responses of samples of the same crystal from the faces of the prismatic and pyramidal growth sectors to exposure are different. In the former case, they soften; in the latter case, the hardening stage follows the softening stage. However, in both cases, the microhardness returns to the initial value. At B²t_m values from 19 to 37 T² min, the amplitudes and durations of the effect do not change, but in the narrow range of 37–43 T² min, the lifetime of the modified state increases sharply with transition to a new level: “sharp” peaks with a half-width of ~2 days are transformed to trapezoids with the width of the horizontal side of ~1–2 weeks. A physical scheme of the observed effects has been proposed.     

Peculiarities of the diffraction contrast in plane-wave X-ray topographs of weakly deformed crystals in the bragg geometry

The regularities of the topographic contrast formation in weakly deformed nonabsorbing crystals in the Bragg geometry for the diffraction of a plane X-ray wave have been investigated by the method of Riemann functions. It is shown that in this case the extinction contrast has an interference character, alternates, and is proportional to the strain gradient rather than to the squared strain (like in the case of strong lattice distortions). The data of the analysis are compared with the results of a model numerical experiment. The possibility of implementing an X-ray-acoustic resonance in the Bragg geometry is shown.     

Spiropyrans and spirooxazines. 3. Synthesis of photochromic 5′-(4,5-diphenyl-1,3-oxazol-2-yl)-spiro[indoline-2,3′-naphtho[2,3-<Emphasis Type="Italic">b</Emphasis>]pyran]

The reaction of 2-hydroxy-3-(4,5-diphenyl-1,3-oxazol-2-yl)-1-naphthaldehyde with 1,2,3,3-tetramethyl-3H-indolium perchlorate afforded photochromic spiro[indoline-2,3′-naphthopyran] containing a 4,5-diphenyloxazole group in position 5′ of the naphthopyran fragment. The merocyanine form of the spiropyran gave complexes with bivalent heavy cations.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 693–697, March, 2005.     

Synthesis and Structure of a New Ruthenium(II) Clathrochelate and the Use of a Highly Porous Ceramic Material with an Immobilized Complex in the Oxidative Conversion of Methane

Kinetics and Catalysis - A new ruthenium(II) cage complex with polar terminal groups in the apical substituents has been synthesized; the molecular design of the complex contributes to the...     

A Bandpass Filter Based on Dielectric Layers with a Strip Conductor Subwavelength Grating at Their Interfaces

Doklady Physics - The design of a multilayer bandpass filter has been investigated, in which each of the half-wavelength resonators consists of two dielectric layers with outer strip conductor...     

Synthesis and Antimicrobial Activity of Some New Isatins Containing Benzotriazole Fragment

Russian Journal of General Chemistry - New isatin derivatives bearing benzotriazole substituent at the endocyclic nitrogen atom were synthesized. The resulting compounds and trimethylammonium...