Photocatalytic properties and structure of chitosan-based porphyrin-containing systems

The photocatalytic activity of the disodium salt of substituted hematoporphyrin in a model reaction of tryptophan oxidation in the presence of chitosan with different molecular masses and a block copolymer of ethylene and propylene oxides (Pluronic F-127) is studied. It is shown that, in the presence of the Pluronic, the catalytic activity of the chitosan-porphyrin system increases. The structure of chitosan-Pluronic systems, depending on the molecular mass of chitosan and the presence of porphyrin, is examined by AFM. A pleasible mechanism of the influence of the Pluronic on the photocatalytic activity of chitosan-por-phyrin systems is proposed.     

Self-similar properties of collisions between light nuclei

A new way of representing data on the fragmentation of nuclei is suggested. The self-similar behavior of these processes, that is dictated by their kinematics, is demonstrated. The convenience of working in accelerated nuclei is emphasized, particularly for the determination of the binding energy of a wide class of nuclear fragments.     

Synthesis of polymerizable photochromic spironaphthoxazines

Hydrogenatjon of 8-nitrospironaphthoxazine (1) resulted in the corresponding amine (2). Acylation of compound 2 yielded the N-methacryloyl derivative (3). Radical polymerization of the latter resulted in its copolymers with styrene, which possess photochromic properties.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1243–1245, May, 1996.     

Cross sections of the interactions of He nuclei with protons

⁴He-p collisions at two values of⁴He momenta 8.6 GeV/c and 13.6 GeV/c as well as the³He-p collisions at 13.5 GeV/c have been studies using the one-meter JINR hydrogen bubble chamber. Total, elastic, topological and reaction cross sections have been measured. The cross sections have been determined on a sample of minimum biased events.     

Modification of commercial oligomers with diphenyldiacetylene and <Emphasis Type="Italic">p</Emphasis>-diethynylbenzene polymers

Diphenyldiacetylene and p-diethynylbenzene homopolymers and copolymers exhibit high resistance to heat and thermal oxidation. Their composites with commercial oligomers were examined.     

SCF impregnation of polymer matrices with stable nitroxyl radicals

The ESR method is used to study the impregnation of a set of polymer matrices (co-polymer F-42, polyvinylchloride, polycarbonate, polymethylmethacrylate) with stable nitroxyl radicals of 2,2,6,6-tetramethyl-4-oxypiperidin-1-oxyl (TEMOPO) in a supercritical carbon dioxide medium. The amount of the substance incorporated into the polymer matrices increases with increase of the mass of TEMOPO samples used and converges to the limit values that for F-42 and polyvinylchloride samples are 9.6 × 10²⁰ and 7.5 × 10²⁰ paramagnetic centers per gram of the polymer, respectively. At the same time, no formation of TEMOPO clusters is observed; the spatial distribution of radicals absorbed by the polymer film is close to random and is independent from the film thickness.     

A laser based fiducial line for high precision multipoint alignment system

The next generation of linear colliders is very demanding concerning the alignment tolerances of their components. For the CLIC project, the reference axis of the components will have to be pre-aligned within 10 μm at 1 sigma with respect to a straight line in a sliding window of 200 m. A solution based on stretched wires with wire positioning sensors has been proposed in order to fulfill the alignment requirements in the Conceptual Design Report of the project. This solution has some drawbacks and laser based alternative solutions are under study in order to validate the wire solution and possibly replace it. A new proposal is introduced in this paper, using a laser beam over 150 m as a straight alignment reference, with the objective of having an uncertainty in the determination of its straightness within 10 μm. Sensors coupled to the components to be aligned, would provide after calibration the horizontal and vertical offsets with respect to the laser beam, within a few micrometers, in their coordinate system. The method is based on the laser beam space stabilization effect when a beam propagates in atmospheric air inside a pipe with standing acoustic wave. The principal schemes of corresponding optoelectronics devices and temperature stabilization solutions are also proposed, making probable the extension of the laser fiducial line up to a 500 m length.     

Self-assembly of polymer layers with mobile grafting points: Computer simulation

The Monte Carlo method is used to study macromolecule layers with mobile grafting points during deterioration in the solvent quality. If the chains are rigidly grafted onto the surface, the micelle core is bonded to the surface through chain fragments that are strongly extended along the surface, but if the points are fairly mobile, the micelles are dense aggregates maximally segregated from the surface. In addition, an increase in the mobility of the chains leads to increase in the mean aggregation number of the micelles, its dispersion, and height of the aggregate.     

Correlation effects in the production of <Superscript>3</Superscript>He nuclei in <Superscript>16</Superscript>O<Emphasis Type="Italic">p</Emphasis> collisions at a momentum of 3.25 GeV/<Emphasis Type="Italic">c</Emphasis> per nucleon

New experimental data on the dependence of the mean multiplicities and kinematical features of ³He nuclei produced in ¹⁶Op collisions at a momentum of 3.25 GeV/c per nucleon on the degree of excitation of the fragmenting nucleus are presented. Strong correlations between the multiplicities of negatively charged pions and ³He nuclei are found.