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Light scattering in a 3% aqueous solution of hydroxypropyl methylcellulose (metolose) is studied under nonequilibrium conditions within a temperature range of 303–353 K, i.e., in the neighborhood of the phase transition temperature (336 K). It is established that the light scattering intensity undergoes considerable fluctuations in this temperature interval. It is shown that they are caused by quasi-periodic motions (density fluctuations) appearing in the strongly nonequilibrium state of the solution.

Phase transitions in nano-sized systems are of fundamental importance in a variety of fields, including sustainable energy and the pharmaceutical industries. Here we report the thermal properties of undecylenic acid nanocrystals in silica gel pores of different sizes and the chemical composition of the pores’ surface. The results of N2 absorption at 77 K, thermogravimetric method, powder XRD method, and differential scanning calorimetry were analyzed to gain an insight into the processes accompanying the phase transition. We using a thermodynamic model of nanocrystal melting in an open porous system and analyze temperature dependence of the effective size of pores, as well as the dependence of the specific heat of melting on the effective size of the pores. This model helps us obtain the following properties of the undecylenic acid: the density of nanocrystals, pressure inside the nanocrystal, the relation between the surface tension coefficients and specific entropies on the nanocrystal-porous matrix interface and melt-porous matrix interface. We demonstrate that as the nanocrystals of the undecylenic acid form in the cavities of the porous matrix, the pressure in such nanocrystals, and thus their densities are much lower than pressure and density in bulk crystals of the undecylenic acid. However, when the crystallization of the nanocrystals occurs in the presence of aliphatic chains grafted on the silica gel pore walls, these chains become embedded into nanocrystals. As the result, the character of the change of properties reverses: both the pressure in the undecylenic acid nanocrystals and their density become larger than those for a bulk undecylenic acid crystal. Throughout the paper, we also contrast the behaviour of a polar undecylenic acid in pores with that of nonpolar 1-octadecen molecules.

The possibility of verifying benchmark experiments which are necessary for design validation of the blankets of the TIN-ST thermonuclear neutron source based on the I-2 proton accelerator using neutrons from the reaction 7Li(p, n) is analyzed. It is shown that modern software and databases are effective in calculating the neutron spectra for two types of thorium blankets: solid-state and molten-salt. The hardware and procedures used to develop an adequate idea of the spectral characteristics of the neutron fluxes from plasma and accelerator sources are examined. The results can become the basis for designing micromodels of blankets for subsequent verification benchmark experiments.

A subcritical molten salt reactor with an external neutron source is studied computationally as a facility for incineration and transmutation of minor actinides from spent nuclear fuel of reactors of VVER-1000 type and for producing 233U from 232Th. The reactor configuration is chosen, the requirements to be imposed on the external neutron source are formulated, and the equilibrium isotopic composition of heavy nuclides and the key parameters of the fuel cycle are calculated.

A subcritical molten salt reactor is proposed for minor actinides (separated from spent fuel VVER-1000 light water reactor) incineration and for 233U conversion from 232Th. Here the subcritical molten salt reactor with fuel composition of heavy nuclide fluorides in molten LiF–NaF–KF salt and with external neutron source, based on 1 GeV proton accelerator and molten salt cooled tungsten target is considered. The paper presents the results of parametrical analysis of equilibrium nuclide composition of molten salt reactor with minor actinides feed in dependence of core dimensions, average neutron flux and external neutron source intensity. Reactor design is defined; requirements to external neutron source are posed; heavy nuclides equilibrium and fuel cycle main parameters are calculated.

The transition to chaos in a semiconductor superlattice coupled to an external resonator is studied. It is shown that the transition to chaos proceeds through intermittency. It is found that the system exhibits broadband generation regimes, which is of direct interest for the practical use of nanostructures in data transmission systems.

A precise monitoring of reductionoxidation (RedOx) potential is necessary for using molten salts as fuel compositions and coolants in molten-salt reactors as well as for pyrochemical processing of a spent fuel. So, low over-potentials (~10 mV) are required for rigorously selective extraction of impurities out of the molten salt due to a permanent diffusive cathode polarization in galvanic cell. At the same time, a weak identification of cationic disproportionation (Mk+Ml+) of metal impurities in liquid salts reflects the common defect of all known internal monitoring tools using salt as a sensor: realizing high over-potential and thereby strong polarization of the cathode. It leads to appreciable energy deformation of allowed electron states in the molten salt near the electrodes so that metal components of the basic salt are extracted out of the salt solution together with the selected impurity. Obviously, such the kinetic monitoring of RedOx potential cannot be a precise method since there is impossible eliminating the uncertain polarizing cathode effects in the galvanic cell with the molten salt as an electrolyte. Therefore a monitoring of the RedOx potential of liquid salts by means of an external potentiometer is necessary. This method is based upon the using of a gauge with Na+βAl2O3electrolyte as a solid membrane with unipolar sodium conductivity assigned for monitoring a thermodynamic activity, , of neutral sodium atoms (Na0) in the molten salt. The principle of operation of such the gauge is based on the e.m.f. method. A measuring electrode, Pb [N (a thin layer of liquid lead on the solid electrolyte), directly contacts with the molten salt, easily exchanges by dissolved sodium atoms, and corrosive protects the solid electrolyte. The e.m.f.,E, of this electrode is defined relatively a reference electrode (liquid sodium) located on the other side of solid electrolyte, Na+βAl2O3, in the four-layer galvanic cell: NaNa+βAl2O3Pb [Nsalt [], by equation,E= (RT/F) ln, whereRis the universal gas constant,Tis Kelvin temperature,Fis Faraday constant.

A system for adiabatic trapping of injected particles into the acceleration mode was developed and used to increase the intensity of the ion beam accelerated in the booster synchrotron of the ITEP-TWAC accelerating-storage facility at the Institute for Theoretical and Experimental Physics. Using numerical simulation, the parameters of the injected beam were optimized and the conditions for the absence of particle loss upon a changeover into the acceleration mode and subsequent acceleration to the maximum energy were determined. The effect that the characteristics of a system controlling the radio frequency of the accelerating field had on the dynamics of synchrotron motion and the particle loss was investigated. During development and adjustment of a complex of equipment that provided optimal conditions for adiabatic trapping and acceleration of C4+ ions with an initial energy of 1.3 MeV/amu, the trapping efficiency was as high as 80%, being limited only by the initial distribution of the momentum spread in the injected beam.

The reconstruction of a system of ring-shaped accelerators has been completed at the Institute of Theoretical and Experimental Physics: carbon nuclei have been accelerated in the U-10 synchrotron up to maximum energy 4 GeV/amu C4+ ions from a laser ion source are preaccelerated in the I-3 linear injector up to 1.5 MeV/amu and in the UK booster synchrotron up to 50 MeV/amu, injected via the charge-transfer scheme C4+ → C6+ into the U-10 synchrotron on an increasing magnetic field and accelerated to maximum energy. The basic technological features of the acceleration scheme employed and the results of the first physical experiment with relativistic carbon nuclei are described.

C6+ ions with energy 200 MeV/nucleon have been accumulated in the chamber of the ring magnet of the U-10 proton synchrotron used as a storage ring in the TWAC setup. A C4+ ion beam from the laser source was first accelerated in the I-3 injector up to 1.3 MeV/nucleon and in the UK booster synchrotron up to final energy with periodicity 3.5 sec. Ions have been accumulated in U-10 using the multiple charge-exchange injection scheme C4+ → C6+. An increase in the ion intensity in the accumulator has been observed during several injection cycles. Experimental data on the attained parameters of the accumulated beam are presented, and the status of the optimization of the accumulation regime is discussed.

A complex approach based on the consistent modeling of neutron-physics processes and processes of cascade separation of isotopes is applied for analyzing physical problems of the multiple usage of reprocessed uranium in the fuel cycle of light water reactors. A number of scenarios of multiple recycling of reprocessed uranium in light water reactors are considered. In the process, an excess absorption of neutrons by the 236U isotope is compensated by re-enrichment in the 235U isotope. Specific consumptions of natural uranium for re-enrichment of the reprocessed uranium depending on the content of the 232U isotope are obtained.

The design of a laser oscillator with a stabilized frequency composition and a stabilized intensity of output radiation is described. The oscillator’s basic component is a TEA CO2 module pumped by a self-maintained discharge and operating in a repetition-rate mode at a frequency of up to 3 Hz. A circuit for the formation of a self-maintained homogeneous discharge in the working volume of a CO2 + N2 + He mixture at atmospheric pressure is the basic component of the gas-discharge module. This circuit is based on the generation of a high-voltage pulse with a special profile, which provides high-reliability excitation of a discharge and pulse-to-pulse reproducibility of the discharge characteristics. The use of a hybrid circuit in the optical oscillator allows selection of a single longitudinal mode in the output radiation spectrum, thus eliminating undesirable interference phenomena, which lead to instability of the instantaneous values of the radiation intensity. During the development of the oscillator, the optimal operating parameters of the hybrid circuit were obtained, which ensure the high quality and reproducibility of the spatiotemporal and energy parameters of laser radiation.

The results of the development of the ITEP accelerator carbon ion injector based on a repetition-rate CO2 laser ion source are described. The improvement includes a modified pulsed HV-feeding generator for the discharge formation in the laser gas mixture. The advanced discharge module ensures essential increase of the laser active volume and specific electrical deposition energy. The comparative computer simulations of the discharge characteristics for the improved and the prototype lasers are applied. The design and the output spatial-temporal parameters of the free-running laser “Malish-M” are shown, so the significant increase of the laser power is reached. The spatial characteristics of the laser beam obtained with diffraction calculations are compared to measured radial distribution of the energy density. The target laser intensity and the different channels of the energy loss of the laser beam in the optical scheme are estimated. Finally, the output C4+ current trace of heavy ion injector as well as the injector scheme are shown.

The present paper deals with investigation of the possibilities for reducing the risk of proliferation of fissionable materials by means of increasing the degree of protection of fresh fuel intended for light-water reactors against unsanctioned use in the case of withdrawal of a recipient country of deliveries from IAEA safeguards. It is shown that the use of recycled uranium for manufacturing export nuclear fuel makes transfer of nuclear material removed from the fuel assemblies for weapons purposes difficult because of the presence of isotope 232U, whose content increases when one attempts to enrich uranium extracted from fresh fuel. In combination with restricted access to technologies for isotope separation by means of establishing international centers for uranium enrichment, this technical measure can significantly reduce the risk of proliferation associated with export deliveries of fuel made of low-enriched uranium. The assessment of a maximum level of contamination of nuclear material being transferred by isotope 232U for the given isotope composition of the initial fuel is obtained. The concept of further investigations of the degree of security of export deliveries of fuel assemblies with recycled uranium intended for light-water reactors is suggested.

A characteristic of the present status of nuclear power in Russia is that in the next few years it will be necessary to make basic technological and economic decisions that will have long-term consequences. These decisions must concern all aspects of the nuclear-power complex. Specifically, at the present time there is no validation of the present and future requirements for the capacity of serially manufactured power-generating units of nuclear power plants with VVER or fast reactors. The problem of choosing the unit capacity of a nuclear power plant must be examined taking account of different factors and not solely from the standpoint of minimizing the capital and operational components of the cost of electricity. The main objective of this work was to develop recommendations for validating the optimal capacity of powergenerating units in nuclear power plants (capital costs, construction time, harm due to unanticipated stoppage of the power-generating units, unification, manufacturing quality, harm due to accidents, and so forth), the possibilities of electric grids, and the regional demand for electricity.

Basic problems in neutron physics, structural materials of fuel rods, and assemblies (FA) for a new generation light-water reactors with supercritical parameters of coolant are considered.

Coevolutionary relationships of ticks of the Ixodes genus with causative agents pathogenic for human of viral, bacterial, and protozoan nature are considered using the method of polymerase chain reaction (PCR). Peculiarities of genotypic composition of ticks-vectors are analyzed, which differ in malate dehydrogenase and of which alleles are investigated by the polyacrylamide gel electrophoresis method. The inherited phenotypic differences of population composition of 2 tick species of the Ixodes genus differing by the presence of exoskeleton anomalies and the content of ions of heavy metals-pollutants accumulated in the tick body are investigated. The character of interaction of various tick-borne pathogens in the tick body and the degree of danger of these tocks depending on geno-and phenotypic properties of the populations throughout their area are determined.

A universal fiber-optic pyrometer for the molecular-beam-epitaxy growth module developed in collaboration with JSC Semiconductor Technologies and Equipment is described. This instrument is designed for controlling the technological process of growing semiconductor heterostructures on substrates of various types (GaAs, InP, Si, and sapphire). The pyrometer allows measurements of the temperature of semiconductor substrates to be performed in the range 450–1200°C with an accuracy no worse than ±0.5% under the conditions when such characteristics as the emissivity of the material, the transparency of the optical medium, and the dimensions of the studied surface are unknown. These feasibilities can be realized owing to the use of a procedure of periodic calibration of the pyrometer against an actual object directly during the technological cycle with the use of additional information on the object temperature.

The development of low-capacity nuclear power plants (LCNPs) in our country and the world is reviewed. Examples of designs which have been implemented are examined. Modern designs developed in our country and abroad are presented and analyzed. The requirements which LCNPs must satisfy without on-site refueling are formulated. The prospects for developing low-capacity nuclear power plants to provide energy and economic security in remote regions of our country are examined.

Investigating the microstructure and atomic dynamics of solid solutions and the physicochemical processes occurring in them will make it possible to adjust the properties of the solutions in steps, according to prescribed indicators, by using alloying additives. The concept of designing an oxide fuel may be promising for the development of a new generation of nuclear reactors.

High-power field-effect transistors (FETs) are among the main applications of heterostructures based on group III metal nitrides, which in most cases implement the classical GaN/AlGaN structure with a single junction. An alternative approach based on the use of double heterostructures with imporved two-dimensional electron gas (2DEG) confinement offers a number of advantages, but such structures are usually characterized by a lower carrier mobility and density (in GaN layers of reduced thickness) as compared to the values in the single-junction structures. Optimization of the heterostructure design and ammonia MBE growth conditions allowed us to obtain multilayer AlN/AlGaN/GaN/AlGaN heterostructures with quantum wells, which are characterized by a 2DEG carrier mobility of 1100–1300 cm2/(V s) and a sheet electron density of (1.1–1.3) × 1013 cm-2. Experimental FETs based on the obtained multilayer heterostructures in a static regime exhibit working current densities up to 0.6 A/mm at a transconductance of up to 150 mS/mm and a breakdown voltage above 100 V.

This paper presents the results of computational studies using an estimated value of the increase in VVER-1000 fuel burnup using zirconium displacers, placed on some of quiding channels of the safety and control system rods. The investigations were performed using the CONSUL program system which is designed to calculate the characteristics of the light-water nuclear reactors based on mutually consistent calculations of neutron, temperature and isotopic films

A system of new technical solutions, which will make it possible to develop a reactor system using a coolant with supercritical parameters and efficiency 44%, solving the main problems of the nonuniformity of coolant heating in the core, is examined. This sytem contains a core based on fuel micropellets, a multistep fuel assembly with transverse coolant flow, coolant mixing after each step, and continual reloading of fuel micropellets into each fuel assembly.

The possibilities of using high-temperature reactors operating together with a gas turbine are determined for nuclear-powered icebreakers. The advantages of such systems over previously used nuclear-powered systems and diesel-electric propeller systems are examined. The possibilities of using the MARS-S reactor and gas-turbogenerators, utilizing the heat from the exhaust gases, in nuclear-powered icebreakers are studied. The characteristics of the MARS-S and propeller electric system of a nuclear-powered icebreaker with drive-shaft power up to 90 MW are presented. The possibility of using such systems in floating electric power plants utilizing heat for driving a counterpressure turbine is examined. A version of a single-reactor ship power plant for a lighter and an icebreaker, such as Taimir, is presented.

A new method for determining the weights of eigenmodes in a weakly multimode optical fiber with strong linear anisotropy is developed using the geometric approach. The proposed method is based on the measurement of geometric parameters of the lines of equal intensity (isolines) in the vicinity of a zero point of the field intensity distribution pattern at the output face of the fiber. Using this method, the weights of eigenmodes in a fiber have been determined upon computer processing of the experimental images of intensity distributions observed upon displacement of a probing laser beam relative to the center of the input face. The results are compared to theoretically calculated weights of the eigenmodes.

The mode structure (the orbital number l = 1) of a few-mode weakly guiding optical fiber with high linear birefringence and a regular twist of its anisotropy axes is investigated. It is shown that, for certain values of twist pitch, the modes with l = 1 are almost pure linearly polarized optical vortices in the local coordinate system associated with the anisotropy axes. The range of values of twist pitch in which twisted fibers sustain propagation of linearly polarized optical vortices is determined numerically.

An improved design for the RBETs-M reactor is examined. The design is characterized by innovative solutions to various problems. These solutions make it possible to improve safety and cost-effectiveness as compared with the base RBETs design. The innovative solutions include using 15N-based nitride fuel, a two-loop scheme with no main circulation pumps, a gas-lift system in the first loop, passive systems for removing heat and stopping the reactor, and others.

An optical pyrometer designed for precision measurement of the GaAs substrate temperature during MBE growth is considered. The pyrometer can be calibrated against a certain characteristic absolute temperature that is visually determined from a change in the RHEED pattern. This enables one to calculate the absolute temperature of the substrate with regard to its radiant emissivity and minimize the inaccuracy of radiation temperature measurement. The inaccuracy is associated with the deposition of growth products on the pyrometer window.

The need for fast reactors in nuclear power is discussed. The advantages of fast helium reactors over fast liquid-metal reactors are shown. Fast helium reactor concepts and the possibilities of improving breeding by using fuel of higher density than oxide fuel, specifically, carbides and nitrides, are examined. It is indicated that the development and use of high-temperature helium-cooled thermal- and fast-neutron reactors are promising as part of an international collaboration in nuclear power in the 21st century.

The construction of the Terawatt Accumulator (TWAC) facility is nearly completed at the ITEP in Moscow. All the major milestones have been successfully passed with a beam of carbon ions, except for the final result (the high power beam accumulation), which is on the way. The beam of C4+ ions delivered by the laser ion source is accelerated up to the energy of 300 MeV/amu by two steps—in the linear injector I3 and in the booster synchrotron UK. The accelerated beam is extracted from the UK ring and transferred to the U10 accumulator ring. Non-Liouvillian stripping technique (C4+ ⇒ C6+) is applied for stacking of C6+ batches into the accumulator ring U10. First experiments with extracted beam of ions have started in 2002. Status of the TWAC components, current results of activities aiming at mastering the ion beam stacking technique, and outlook for the TWAC advance are presented.

Spectral density of random alternating current, which is induced by turbulent pulsations of electrolyte velocity in a cell, is theoretically analyzed within the Ershler–Randles charge transfer model in the Nernst diffusion layer approximation. The effect of electrode potential on the spectral current density is analyzed at various frequencies of hydrodynamic pulsations.

The basic technical characteristics of a conceptual design of micropellet fuel autonomous liquid-salt reactor MARS for low power levels are presented. Two variants with core service lives 15 and 60 yr are presented. It is shown that this concept satisfies the requirements which autonomous low-power nuclear power systems must meet.

The present measurements of the components' surface resistance to laser-induced damage has been completed to facilitate development and construction of the “Luch” laser system, a four-channel Nd-phosphate glass laser with a full output energy of E = 14–16 kJ. The study describes a method that, with a series of experimental data obtained from a single sample, allows us not only to estimate the threshold fluences, but to take into account the statistical nature of the surface damage. In a number of experimental situations this method makes it possible to estimate damaging fluences even from the result of a single exposure of the studied surface. Estimated threshold fluences for various optical elements are presented: K8 glass, experimental phosphate laser glass KGSS-0180, high-reflecting and antireflecting thin-film coating of elements. The 1.054-μm radiation pulse with half-height duration of 4 ns and the irradiation spot of ∼4 mm in diameter were used in the experiment.

An experimental setup and a technique for measuring the transient period before a stationary cavitation in a liquid by the evolution of the cavitation noise spectrum are described. The time dependences of harmonic amplitudes both near the radiator and outside the cavitation region are presented. From the form of these dependences, the characteristic transient periods preceding the stage of a fully developed cavitation in water and in transformer oil are calculated. A formal scheme for describing the cavitation region is proposed.

The results of comparative calculations of material balances are presented for two concepts for the growth of nuclear power in the 21st century. The concepts of growth on the basis of fast reactors without expanded breeding of fuel and the conventional concept with a two-component structure of nuclear power growth are examined. The advantages of the conventional concept, capable of producing substantial savings of natural uranium and/or making it possible to increase substantially the installed capacities of nuclear power plants, are demonstrated.

Investigations performed to substantiate the strategy of safe development of nuclear power in Russia, taking account of the available resources, the state of the economy, and the transition of the country to a market economy, have shown that plutonium used as reactor fuel makes it possible to obtain a comprehensive solution to fundamental problems, many of which cannot be satisfactorily resolved with a uranium-based open fuel cycle. Thus, it has been established with respect to nuclear safet y that on the basis of physical and technical principles liquid-metal-cooled fast reactors have a greater potential for inherent safety; from the standpoint of nuclear disarmament it is of fundamental importance to decrease the amount of accumulated weapons and power plutonium and correspondingly to decrease the risk of proliferation of this nuclear material at the storage stage; fr om the standpoint of solving ecological problems the concept of radiation-safe storage of nuclear wastes, which can be implemented only by extracting plutonium from the spent fuel, is attractive; and so on. Thus, analysis of the assumptions and directions of development of nuclear power under altered conditions confirms the position that the use of plutonium in reactor fuel is one of the most fundamental aspects of the internal logic of the deve lopment of nuclear power. In the opinion of the authors rejection of plutonium will lead, directly or indirectly, if not to the cu rtailment of nuclear power, then to substantial limitation of its role in large-scale power production in the future. Utilization of Plutonium in VVER-1000. Preliminary investigations and the experience gained in the European countries in working with mixed uranium‐plutonium fuel in light-water reactors attest to the real possibility of using plutonium as VVER-1000 fuel. Computational investigations of the possibility of using power plutonium in VVER-1000 type reactors have been per

The development of energy production in the 21st century will be subject to more uniform per capita and regional consumption. Among the competing sources of energy, the positive qualities of nuclear power-unlimited fuel resources, high energy intensiveness, and ecological compatibility with the possibility of the wastes being highly concentrated—predetermine the development of large-scale nuclear power. The conditions for the development of such nuclear power are its ecological effectiveness and safety (of the reactors and the fuel cycle with the production of wastes), nuclear fuel breeding with adequate characteristics, and guarantees of nonproliferation of fissioning materials.

The characteristics of the radiation of a laser with intracavity scanning with the aid of electrically controlled spatiotemporal modulators based on a transparent electro-optical PLZT ceramic were investigated. The possibility of the generation of packets of single pulses of scanning laser radiation with a repetition frequency up to 100 kHz, and up to 10 kHz under the conditions of continuous flashlamp pumping with an intracavity spatiotemporal modulator is demonstrated. Possible applications of the laser are discussed.

The results of studies of radiation parameters of a chemical non-chain DF laser (emitting in the range from 3.5 to 4.1 μm) with an intracavity control of the radiation pattern with the help of spatiotemporal modulators based on PLZT electrooptic ceramics are presented.

We report preliminary results on the transfer of the ammonia MBE technology of AlN/AlGaN/GaN/AlGaN heterostructures to silicon substrates. Optimization of the growth conditions allowed the number of macroscopic cracks in the epilayers to be reduced and ensured the growth of heterostructures with two-dimensional electron gas, which are suitable for the creation of field-effect transistors. The saturation current of prototype devices based on the heterostructures grown on silicon substrates are comparable with the analogous parameter of devices grown on sapphire and exhibits no decrease related to thermal scattering at high bias voltages.

An analysis aimed at finding possible neutrino radiation accompanying gamma-ray bursts in a 24-h period about them is performed on the basis of the data in the 4B BATSE Gamma-Ray Burst Catalog and data from the Baksan scintillation telescope according to a program for finding neutrinos from collapsing stars. Values significantly exceeding the background are not discovered. A lower bound for the distance to the source is established under the assumption that the anticipated radiation has characteristics similar to the characteristics of collapse neutrinos. It attests to the cosmological origin of gamma-ray bursts with a high degree of probability.

The method is described and the experimental results are reported of an investigation of the precision of control of the angular distribution of radiation in a laser amplifier with phase conjugation coupled to a master oscillator with an intracavity light-controlled space—time modulator. It is shown that the precision of control of the direction of radiation is at least 0.3 of the diffraction divergence of a beam and the response time of the modulator to a control signal is 500 μs. The results are given of a study of the precision of phase conjugation of radiation by double reflection from stimulated Brillouin scattering mirrors, including results obtained under conditions simulating self-interaction of radiation.

The parameters of high-power laser diodes operating at λ=0.94 μm, based on MBE-grown In0.1Ga0.9As/AlGaAs/GaAs quantum-dimensional heterostructures, are reported. The laser diodes manufactured using an optimized MBE technology and specially selected dopant profiles are characterized by a lowthreshold current density, a high optical output power, a high differential quantum efficiency, and a long working life (above 10000 h).

Most common types of fiber optical sensors (FOS) and their applications in monitoring of civil building are analyzed in this paper. The new sensor based on twisted optical fiber with closed ends and varied twisting step is designed. The mathematical modeling of the sensor and a number of experiments to investigate its characteristics, including the sensitivity, were realized. The method of frequency incoherent reflectometry was proposed to use in order to collect information from FOS. Data acquisition software was designed.

We theoretically analyze the influence of magnetic field on small-signal absorption and gain in a superlattice. We predict a very large and tunable THz gain due to nonlinear cyclotron oscillations in crossed electric and magnetic fields. In contrast to Bloch gain, here the superlattice is in an electrically stable state. We also find that THz Bloch gain can be significantly enhanced with a perpendicular magnetic field. If the magnetic field is tilted with respect to the superlattice axis, the usually unstable Bloch gain profile becomes stable in the vicinity of Stark-cyclotron resonances., 4 pages, replaced with final version

The mechanisms of microhardness increase in thermoplastic polypropylene/multi-walled carbon nanotubes (MWCNT) nanocomposites during electron irradiation (Ee = 1.8 MeV) with different absorption doses are investigated. The crystal structure of the nanocomposites, Raman scattering, and microhardness in a MWCNT concentration range between 0.1 and 5.0 wt% is studied in detail. During irradiation, changes in the degree of crystallinity of the polymer matrix, lattice parameters of the topologically ordered phase, Raman scattering, and microhardness show a complex conjugation process between the composite components. Their interaction is accomplished as the result of the formation of new bonds, which appeared with the radiation damages. Furthermore, the crosslinking of the internal MWCNT layers also contributes to an increase in the strength properties of the polymer nanocomposites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers

The basic strategy of Russian nuclear energy is propagation of a closed fuel cycle on the basis of fast breeder and thermal reactors, as well as the solution of the spent nuclear fuel accumulation and resource problems. The three variants of multiple Pu and U recycling in Russian pressurized water reactor concept reactors on the basis of REgenerated MIXture of U, Pu oxides (REMIX) reprocessing technology are considered in this work. The REMIX fuel is fabricated from an unseparated mixture of uranium and plutonium obtained during spent fuel reprocessing with further makeup by enriched natural U or reactor grade Pu. This makes it possible to recycle several times the total amount of Pu obtained from the spent fuel. The main difference in Pu recycling is the concept of 100% or partial fuel loading of the core. The third variant is heterogeneous composition of enriched uranium and uranium–plutonium mixed oxide fuel pins in one fuel assembly. It should be noted that all fuel assemblies with Pu require the involvement of expensive technologies during manufacturing. These three variants of the full core loadings can be balanced on zero Pu accumulation in the cycle. The various physical and economical aspects of Pu and U multiple recycling in selected variants are observed in the given work.

The terawatt picosecond CO 2 -laser design is considered in the paper. The CO 2 -laser system includes itself the following units: a) master oscillator with variable pulse width of 100 ps, and b) laser pre-amplifier being developed on a basis of a ring optical scheme and operating under the gas pressure of 3 atm. Both experimental and theoretical analysis of the CO 2 -laser system is carried out.