Solar and nuclear transport-power modules for different types of spacecraft

The results of a comparative analysis of the effectiveness of transport-power modules of different types (with solar and nuclear power systems, with electric and thermal rocket motors) for placing spacecraft from domestic cosmodromes into geostationary orbit using medium and heavy carrier rockets are presented. The main purpose of this analysis was to substantiate the regions of no-alternative application of nuclear power and power-propulsion systems for solving conventional and qualitatively new space problems in the interests of defense, science, and socioeconomic development of the country. It is concluded that at the present stage it is best not to use them together with medium-class carrier rockets. The results of a comparative analysis of the use of solar and nuclear transport modules together with heavy carrier rockets are presented for the assessment of solving the prospective problem of all-weather round-the-clock operational, highly detailed observation using an orbital system of spacecraft in a geosynchronous orbit, 3 figures. Central Scientific-Research Institute, Russian Ministry of Defense. Translated from Atomnaya énergiya, Vol. 89, No. 1, pp. 15–20, July, 2000.     

Field electron emitter based on a cesium-gold compound film

The formation and transformation of local emission centers during field electron emission from a cesium-gold (CsAu) compound film on a tungsten point emitter has been studied. Stable electron emission from one center reaches a current density of ～10⁸ A/cm². The properties of emission centers change during the take-off of large electron currents and on heating of the emitter. The experimental data are interpreted assuming that the CsAu compound is decomposed by a narrow beam of current passing through the film, with the formation of a several-nanometer-thick gold column and the reverse process of CsAu compound recovery at the column boundaries due to the diffusion supply of cesium.     

1-butene and 2-butenes production using the positional isomerization of butenes catalyzed by sulfonic acid cation exchangers

Pure 1-butene and 2-butenes can be efficiently obtained from butane-butene fractions by combining the positional isomerization of n-butenes on sulfonic acid cation exchanger catalysts with sharp distillation. At 50–60°C, an equilibrium 2-butenes: 1-butene ratio of ～25: 1 is attained. The 2-butenes, which are comparatively high-boiling compounds, can be sufficiently completely separated from detrimental impurities (1,3-butadiene and isobutene), 1-butene, and isobutane by distillation. The back isomerization of the purified 2-butenes into 1-butene with continuous removal of the latter as distillate affords pure 1-butene at a relatively low cost.     

Hierarchical amphiphilic high-efficiency oil–water separation membranes from fermentation derived cellulose and recycled polystyrene

A high-efficiency separation of oil and water can be achieved by using specially designed amphiphilic porous membrane. However, the preparation of such membranes often involves complex multistep chemical processes. Herein, we report an amphiphilic composite membrane (polystyrene [PS]/bacterial cellulose [BC] membrane) consisting of hydrophobic recycled PS and hydrophilic BC, fabricated by a facile in situ fermentation process. Not only these membranes exhibit a combination of contrasting wettability but also comprise of a hierarchical network of microfibers and nanofibers, which makes them ideal for oil–water separation. The structural and morphological properties of as-produced BC, recycled PS membrane, and PS/BC composite membrane were studied by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The ability of the membranes to separate oil and water was tested by using an emulsion of hexane-in-water as the feed and the collected filtrates were characterized by optical microscopy and UV–Vis spectroscopy. PS membranes were unable to separate oil and water, while the PS/BC membrane efficiently separated water from the emulsion. PS/BC composite membranes showed a high water recovery of more than 90%, against only 57% recovery shown by BC. Mechanisms of oil–water separation for each membrane are discussed. The reusability of the PS/BC composite membrane was also demonstrated.     

Pt(IV) Prodrugs with NSAIDs as Axial Ligands

A chemo-anti-inflammatory strategy is of interest for the treatment of aggressive cancers. The platinum (IV) prodrug with non-steroidal anti-inflammatory drugs (NSAIDs) as axial ligands is designed to efficiently enter tumor cells due to high lipophilicity and release the cytotoxic metabolite and NSAID intracellularly, thereby reducing side effects and increasing the therapeutic efficacy of platinum chemotherapy. Over the last 7 years, a number of publications have been devoted to the design of such Pt(IV) prodrugs in combination with anti-inflammatory chemotherapy, with high therapeutic efficacy in vitro and In vivo. In this review, we summarize the studies devoted to the development of Pt(IV) prodrugs with NSAIDs as axial ligands, the study of the mechanism of their cytotoxic action and anti-inflammatory activity, the structure–activity ratio, and therapeutic efficacy.     

Formation of High-Conductive C Subunit Channels upon Interaction with Cyclophilin D

The c subunit of the ATP synthase is an inner mitochondrial membrane (IMM) protein. Besides its role as the main component of the rotor of the ATP synthase, c subunit from mammalian mitochondria exhibits ion channel activity. In particular, c subunit may be involved in one of the pathways leading to the formation of the permeability transition pore (PTP) during mitochondrial permeability transition (PT), a phenomenon consisting of the permeabilization of the IMM due to high levels of calcium. Our previous study on the synthetic c subunit showed that high concentrations of calcium induce misfolding into cross-β oligomers that form low-conductance channels in model lipid bilayers of about 400 pS. Here, we studied the effect of cyclophilin D (CypD), a mitochondrial chaperone and major regulator of PTP, on the electrophysiological activity of the c subunit to evaluate its role in the functional properties of c subunit. Our study shows that in presence of CypD, c subunit exhibits a larger conductance, up to 4 nS, that could be related to its potential role in mitochondrial toxicity. Further, our results suggest that CypD is necessary for the formation of c subunit induced PTP but may not be an integral part of the pore.     

A Shielded 800-kV Pulse Generator at an Energy of 32 kJ

The electric circuit, design, and characteristics of a shielded oil-insulated Marx pulse-voltage generator (PVG) with a stored energy of 32 kJ and an output voltage of 800 kV are described. The PVG charges a water-insulated forming line of the STRAUS-R accelerator of a pulsed electron beam to 700 kV within a time of <1 μs. Two И ЭПM-100-0.4 УXЛ 4 capacitors are installed in each of its eight stages. The switches of the three first stages are 100-kV trigatrons filled with a 40% SF₆ + 60% N₂ gaseous mixture to a pressure of 0.7 MPa. The switches of the other stages are two-electrode spark gaps. The PVG-operation delay time is 108 ± 5 ns at a breakdown-strength margin of each spark gap of ∼80%. The PVG-circuit inductance is ∼1.4 μH. The overall dimensions of the PVG's steel tank are 2400 × 800 × 800 mm (without an output device); the PVG mass is 1700 kg. __________ Translated from Pribory i Tekhnika Eksperimenta, No. 6, 2005, pp. 21–27. Original Russian Text Copyright ? 2005 by Gerasimov, Gordeev, Kul'gavchuk, Myskov, Nazarenko, Pavlov, Sofronova, Suvorov, Shejnov.     

On particle creation and renormalization in a cosmological model with a Big Rip

An exact solution is obtained for a massive scalar field conformally coupled with the curvature in a cosmological model with the scale factor a(t) = a ₀/|t|, corresponding to background matter with the equation of state p = −5ε/3. An expression for the number density of created particles is obtained, and its behavior is studied as the model approached the instant of a Big Rip. Renormalization of the energy-momentum tensor is considered, and it is shown that back reaction of the quantum effects of a conformally coupled scalar field on the space-time metric can be neglected if the field mass is much smaller than the Planck mass and if the time left to the Big Rip is greater than the Planck time.