Transition radiation detectors—“B” trackers manufactured at JINR for ATLAS LHC inner detector

The results of the creation of a transition radiation detector—a “B” tracker on the basis of thin-walled drift tubes (straw tubes) for the inner detector of the ATLAS Large Hadron Collider (LHC)—are presented. The results of preliminary detector testing are described. The basic components and procedures of assembly for 17 eight-layer TRT modules manufactured at JINR are described.     

129I-Mössbauer study of molecular dynamics in the organic superconductor β-(BEDT-TTF)2I3

¹²⁹ I-Mössbauer spectroscopy was applied to study the organic superconductor β _H -(BEDT-TTF)₂ I ₃ withT _c=8 K. The measurements were performed in the temperature range 1.4 K to 160 K. A detailed analysis of the well-resolved spectra, including transmission integral fits, revelas information about the hyperfine interactions and the local binding strength (f-factor) for the terminal and central sites of the linear and symmetricI ₃ ^? anion. A change in the local Debye temperature of both sites of theI ₃ ^? anions is observed around 120 K, where a phase transition was monitored by other methods. Most interesting with respect to the superconducting properties is a change of the relative intensities of the terminal and central iodine sites, which starts below 10 K and increases down to 1.4 K. This behaviour may be attributed to a libral motion of the iodine molecules and seems to be connected with the occurence of superconductivity in this system.     

Methane Reforming with Carbon Dioxide on the Co/α-Al2O3 Catalyst: The Formation, State, and Transformations of Surface Carbon

The interactions of oxidized and reduced Co/-Al₂O₃ (4 wt % CoO) with H₂, CH₄, CO₂, and O₂ and their mixtures are studied in flow and pulse regimes using a setup involving a DSC-111 differential scanning calorimeter and a system for chromatographic analyses. It is shown that treatment with hydrogen at 700°C results in the partial reduction of cobalt oxide to Co. Methane poorly reacts with the oxidized catalyst but readily reacts with the reduced catalyst to form H₂ and surface carbon. The initial surface carbon transforms into other forms, which block the cobalt surface to different extents and differ in the heats of reaction with CO₂. Carbon dioxide may react with the surface carbon to form CO (rapidly) and with metallic Co to form CO and CoO (slowly). Thus, the main route of methane reforming with carbon dioxide on Co/-Al₂O₃ is the dissociative adsorption of CH₄ to form surface carbon and H₂ and the reaction of surface carbon with CO₂ to form CO via the reverse Boudouard reaction.     

Infrared spectra of triorganoacyloxysilanes and their isologs

Conclusions An analysis of the IR spectra of the compounds R₃MOCOR, where R and R=CH₃, C₂H₅ or C₆H₅, testify to a competition between , p-conjugation and d–p-interaction in the M-O bond (for M=Si, Ge), and to the formation of M...O coordination bonds (for M=Sn, Pb).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 164–166, January, 1971.     

Characteristics of volume discharge in gaps with a small interelectrode separation

This paper examines the excitation conditions, ignition ranges, and also the energetic characteristics of high-pressure volume discharge. It is shown that, using the UV radiation of an auxiliary discharge to preionize the active medium, volume discharge turns out to be substantially more stable than if weak x-ray radiation is used, creating an initial electron concentration 10⁸ cm^–3. Data are cited which indicate that the energy entering the gas with the primary discharge increases in proportion to the increase of energy dissipated in the auxiliary discharge. Several results are reported about the effect of electric field homogeneity on the nature of the discharge progression.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 89–94, April, 1986.     

Stabilization of cellulosolytic enzymes by sorption on the plant raw materials surface

Russian Chemical Bulletin - The influence of a cellulosolytic complex sorbed on the plant raw materials surface on the stabilization of enzymes during the subsequent mechanical treatment was shown....     

Mechanochemical and Size Reduction Machines for Biorefining

In recent years, we have witnessed an increasing interest in the application of mechanochemical methods for processing materials in biomass refining techniques. Grinding and mechanical pretreatment are very popular methods utilized to enhance the reactivity of polymers and plant raw materials; however, the choice of devices and their modes of action is often performed through trial and error. An inadequate choice of equipment often results in inefficient grinding, low reactivity of the product, excess energy expenditure, and significant wear of the equipment. In the present review, modern equipment employing various types of mechanical impacts, which show the highest promise for mechanochemical pretreatment of plant raw materials, is examined and compared—disc mills, attritors and bead mills, ball mills, planetary mills, vibration and vibrocentrifugal mills, roller and centrifugal roller mills, extruders, hammer mills, knife mills, pin mills, disintegrators, and jet mills. The properly chosen type of mechanochemical activation (and equipment) allows an energetically and economically sound enhancement of the reactivity of solid-phase polymers by increasing the effective surface area accessible to reagents, reducing the amount of crystalline regions and the diffusion coefficient, disordering the supramolecular structure of the material, and mechanochemically reacting with the target substances.     

Azimuthal Decomposition of the Noise of a Dual-Stream Coaxial Jet

Acoustical Physics - Azimuthal decomposition was used to study the azimuthal composition of noise of a jet issuing from a coaxial nozzle. Various combinations of the velocities of the core and...