Paata J. Kervalishvili

Nanostructures, magnetic semiconductors and spintronics

The aim of this paper is to give a brief overview of recent advances in the area of semiconductor nanomaterials, which represent extremely promising applications for materials with the spin-polarized transport of the charge carriers. It is shown on the basis of the last theoretical and experimental achievements that the development of diluted semiconductors with the controlled disorder and the wide energy gaps as well as the study of their molecular structures are very prospective routes for producing of novel magnetic semiconductors.

Some Neutron Absorbing Elements and Devices For Fast Nuclear Reactors Regulation Systems

It is shown that performed technological, physical-mechanical andradiation tests clearly indicate the prospects of using Neutron Absorbing Elements (NAE) based on B-10 and some rare-earth compounds during the creation of highly effective Control and Safety System (CSS) rods for fast neutron nuclear energetic reactors. Particular attention was paid to the development of new and upgrading of existing computing and real technologies for designing and preparing the optimizing NAE items characterized by all physical and strength properties for obtaining desirable operational parameters of CSS rods on their base.

Microwave in Environmental Technologies and Synthesis of Nano-materials: The Georgian Experience

The present work deals with the recent developments of Georgian scientists and scientific institutions in the field of microwave enhanced processing of mining and metallurgical, polymeric, agricultural, municipal, medical, phytoremediation and radioactive waste and microwave assisted synthesis of nanoparticles and nanomaterials, which can form a scientific and technological basis for movement towards fast economical and social development, environmental safety and security, establishing of the “Green Economics” and Knowledge Based Society and achieving the Sustainable Development. Prospects and capacities of different activities in these directions are analyzed and evaluated. It is also suggested that as a result of rapid development the systems with microwave heating will become an important element of industrial installations for nanosynthesis.

Oscillation and Optical Properties of Viruses and Other Pathogenic Microorganisms: A Review Article

The ability to detect rapidly, directly and selectively individual virus particles has the potential to significantly impact healthcare, since it could enable diagnosis at the earliest stages of replication within a host’s system. Simultaneous acquisition of the vibrational and electronic fingerprints of molecular systems of biological interest, at the interface between liquid media, or at the air /solid, air/liquid interfaces is difficult to achieve with conventional linear optical spectroscopies due to their rather poor sensitivity to the low number of molecules or their maladjustment to water environment (infrared absorption), at the exception of polarization modulation infrared absorption spectroscopy. The shift in energy gives information about the vibrational modes in the system. Infrared spectroscopy yields similar, but complementary information. Spontaneous scattering is typically very weak and as a result the main difficulty of this kind of spectroscopy is separating the weak inelastically scattered light from the intense Rayleigh scattered laser light. Viruses are assembled in the infected host cells of human, animals, or plants.

Quantum Approach to Sensory Information Processing for Modeling of Disasters

In the modeling process of big systems such as different disasters, one of the main points is data collection: data quantity and quality, its manifold and accuracy. The modeling of this kind of processes includes: data mining and recognition (creation of a database), data processing and treatment (knowledge base preparation), and elaboration of conclusions. The quantum information technologies permit by using quantum representation of data, to collect much bigger, more varied and precise information, as well as quantum databank creation, which can be effectively treated by usage of relevant quantum algorithms. For creation of quantum databases, two methods will be dealt with: One is based on quantum numbers usage for processing various parametrical values (attributes of database); next, the database will be presented as its quantum model. Taking into account the quantum and multi parametrical nature of disasters for their clear and precise modeling it is necessary to combine the above mentioned two approaches and jointly quantum search algorithms and quantum query algorithms as well.

Microwave Enhanced Producing of High-Purity Metallic Manganese and Composite Manganese Based Alloys

Experimental research was carried out using representative samples of manganese processing waste disposed in Georgia to achieve secondary recovery of high-purity metallic manganese and form the waste. Manganese hydroxide obtained through microwave ammonium chloride processing of manganese containing sludge was used for obtaining manganese sulphate, electrolytic manganese and manganese based composite alloys. The experimental data showed that microwave utilization of manganese bearing waste can form the basis for the low-cost and environmentally-friendly industrial production of high purity metallic manganese, which can be used for synthesis of manganese doped semiconductors. It can also be used for SHS producing of composite manganese based low-carbon and low phosphorous alloys. The developed methods can partially replace the standard technologies of ferroalloys industry, which uses reducing manganese oxides by carbon. This would significantly decrease the carbon monoxide and carbon dioxide emissions during production of ferromanganese and metallic manganese while reducing the emission of greenhouse gases and mitigating global warming.

Nitride and Sulfide Chemisorbed Layers as the Surface Passivants for A3B5 Semiconductors

A comparative study of the nitride and sulfide chemisorbed layers as the surface passivants are done for (100) surfaces of InAs and GaAs. A chemical model which describes formation of such layers in hydrazine-sulfide and water sodium sulfide solution is developed. According to the model after wet chemical treatment in the hydrazine – sulfide solution a monolayer film of Ga-N forms on GaAs(100) surface. The film is covered by a physisorbed upper layer which can be removed by thermal annealing. In contrast, wet chemical treatment of InAs(001) surface in water sodium sulfide solution results in formation of chemisorbed layer with As-S bond which dissociates under light irradiation. Further annealing at comparatively low temperature induces formation of In-S and of a layer of indium sulfide. Using Auger electron spectroscopy, photoluminescence and Reflectance anisotropy measurements we have shown that the sulfide passivating layer on InAs(100) surface and the nitride passivating layer on GaAs(001) both produce an effective surface electronic passivation of these compounds. However, nitride passivation seems to be more preferable that the sulfide passivation, mainly due to a high stability of Ga-N surface bonds and surface nitride layers. We conclude that the most promising application of the wet chemical nitridation could be preparation of GaAs epi-ready substrates for epitaxial growth of A3-nitrides and A2B6 compounds. On the other hand for narrow gap A3B5 semiconductors the sulfide passivation could be preferable in some aspects.

Combined processing of waste organic polymers and manganese bearing waste/low grade ores into fuels and low-carbon manganese alloys

Georgia could serve as a unique natural testing ground for the development of green industry using advanced technologies for industrial processing of hazardous waste. The goal of the reported work was to improve on the current methods of reprocessing waste by using a combination of a microwave enhanced method of processing used tyres and plastic residues with the microwave enhanced processing of manganese bearing waste and low-grade ores into manganese oxide concentrate. The manganese concentrate could be processed into high-grade manganese alloys (metallic manganese, low-carbon ferromanganese, and composite manganese alloys). Microwave heating required lower energy and resulted in a two-fold increase in yield.

Monte-Carlo Modelling and Experimental Study of Radon and Progeny Radiation Detectors for Open Environment

Solid state nuclear track detectors (SSNTDs) have been widely used as sensors of radon and progeny in long-term dosimetry because they exhibit high detection properties while their cost is very low. Alpha-particle energy calculating codes, specific for every incident particle, increase the Monte-Carlo simulation time significantly. The expression of the alpha particle energy as a function of the distance travelled in SSNTD CR-39 was recently introduced as an alternative approximation for the simulation method. This chapter focused on modelling the response of bare CR-39 detectors to alpha-particles emitted by radon and progeny, through Monte-Carlo methods. In order to determine the efficiency of a combined use of bare CR-39 and cup-type detectors in radon measurements, theoretical and experimental CR-39 efficiency factors for alpha-particles were calculated. Modelling rendered calculation of effective volume for CR-39 detector, based on energy and angular distributions of alpha-particles emitted due to decay of radon and progeny. The relationship between equilibrium factor F and the recorded track density values ratio (of bare and cup-enclosed SSNTDs, respectively) R was calculated. The sensitivity factor kB for bare CR-39 was found equal to kB = (4.6 ± 0.6) [tracks × cm−2]/[kBq × m−3 × h] (assuming the Jacobi’s steady-state model), a value not significantly different from the corresponding kR cup-type value for radon and progeny.

Novel Fuels and Materials for Nuclear Energy Generation Technologies

Existing energy generations technologies both electrical and thermal based on the burning of natural energy carriers are dangerous for biosphere of our planet. It became obvious that the further intensive development of modern energetic and transport leads to large-scale ecological crisis.