Kakha Gorgadze

"Boron nitride (BN) volume and nano-sized materials can be used for many different urgent purposes - from creation of hypersonic civil aircraft (due to high stability and integrity at high temperatures) to the development of effective cancer treatment methods (due to high values of thermal neutron capture cross section of 10B isotope and high energy proton cross section of 11B isotope). Nanostructured hexagonal boron nitride (hBN) is a highly prospective material for the tumor localized boron neutron and boron-proton capture therapy characterized by high biocompatibility and significant efforts have been made to reduce the conventional synthesis and annealing temperature and improve the crystalline structure. The most advanced methods of synthesis of the isotopic enriched h-BN

nanoparticle require synthesis and annealing temperatures higher than 900-1000 OC and quite expensive precursor materials like amorphous boron powder. The newly developed method being reported, utilizes gaseous ammonia and boron trifluoride at synthesis temperatures up to 250 OC and easily available cheap raw materials: gaseous boron trifluoride, gaseous ammonia and potassium chloride. The synthesis by-product undergoes farther processing, finally yielding again in boron trifluoride and ammonia. Despite of the extremely low temperature of synthesis (150-200OC) samples of BN nanosheets and nanoparticles with a clearly defined hexagonal structure have been synthesized using cheap and easily available

raw materials and a simple technological method."

Cancer therapy using high energy charged particles (primary, proton beams) is the most adavanced modality for the treatment of several kinds of cancer successfully used in more than 110 medical centers around the world. Increasing of the biological efficacy and safety of proton (hadron) therapy is a crucially emerging problem of modern medicine and space astrobiology. One of the most productive approaches is the so - called localized combined therapy using various kinds of nano-based fluids and involving nuclear reactions. An optimal "ensemble" of the adjuvant therapeutic modalities must consist of Curie temperature controlled magnetic (in our case, boron nitride encapsulated Ni-Cu and Ag:LaMnO3 nanoparticles) and isotopic enriched boron nitride (10B, 11B) nanoparticles, which can provide the treatment synergistic to radiotherapy. Moreover, due to the boron-proton and boron-neutron capture reactions, isotopic enriched 10 B and 11 B nanoparticles with the appropriate optimal spatial distribution inside and at the tumor boundaries, as a result of nuclear reactions, can generate a sufficient concentration of alpha particles and bring to a

drastical reduce of the number of protons and thermal/epithermal secondary neutrons affecting healthy cells. An optimized distribution of the isotopic enriched 10 B, 11 B nanoparticles and Li atoms can also improve the spatial distribution of the proton beam in body tissues. Mathematical simulation also showed that the enhanced proton therapy coud move close to 12C ion hadron therapy, but without its complications. 

Photon therapy is widely used in more than 110 medical centers around the world. The localized combined therapy using radiotherapy, mild hyperthermia, chemotherapy, photodynamic therapy ROS therapy a prospective tool to increase the biological effectiveness and safety of cancer therapy while the most advanced kind of the hyperthermia is the Curie temperature controlled localized hyperthermia (CTCLH) A principally new approach is the usage of the isotopic enriched 10B and 11B containing nanomaterials (both in the form of pure boron and boron nitride) nanoparticles and boron-neutron and boron-proton capture nuclear reaction products Novel microwave enhanced methods of synthesis magnetic metal nanoparticles, isotopic enriched hexagonal boron nitride (hBN) nanosheets and boron nitride encapsulated magnetic metal nanoparticles for the (CTCLH) and localized boron-neutron and boron-proton capture therapy were developed and their magnetic properties were tested. A novel ovoscopy method of testing the acute toxicity of the synthesized nanomaterials to avian embryos excluding the use of mammals and other living animals for drug testing was examined. 

The physical nature of the increase in the heat capacity of nanomaterials with a decrease in the sizes of their constituent nanoparticles has so far not been clear. This is due to the fact that the existing heat capacity mechanisms are not perfect, since they are not only quantitative, but also from a qualitative point of view, unable to explain many experimental facts. We have proposed a new physical mechanism for the heat capacity of solids, based on the consideration of redistribution of the kinetic energy received by a solid body into a potential (deformation of chemical bonds) and the kinetic energy of the system (temperature) due to a change in the energy of chemical bonds. The less energy of chemical bonds, the more likely they are to deform. With increasing temperature, the decrease in the energy of chemical bonds is due to the growing concentration of the resulting antibonding quasiparticles (AQP), which weaken the chemical bonds between the atoms around which they appear during their chaotic motion. AQP are electrons in the antibonding zone and holes in the bonding zone. The transfer of an electron by heat from the bonding to the antibonding zone with the formation of a hole in the bonding zone means the appearance of an AQP. The greater the concentration of AQP the less the energy of chemical bonds, the more likely they are deformed and the larger the increase in the fraction of the change in the potential energy in the kinetic energy received by the solid body. An increase in the share of potential energy causes an increase in the amount of heat necessary for heating the body by one degree, i.е. its heat capacity. It is shown that as the size of nanoparticles decreases, the effective concentration of AQP increases, which leads to an increase in the probability of deformation of chemical bonds and, correspondingly, to an increase in the fraction of potential energy. Specific examples confirming the truth of the proposed mechanism are given.

Georgia takes active steps for establishment of Radioactive Waste Management System (RWMS) in the country: –Based on the international support the

Centralized radioactive waste Storage Facility (CSF) was constructed and commissioned; –Georgia joined to “Join Convention on the Safety of Spent Nuclear Fuel Management and on the Safety of Radioactive Waste Management”. The first country status report was sent to International Atomic Energy Agency (IAEA) at 2011; –IAEA experts reviewed draft Georgian law “On Radioactive Waste Management”; –The first radiological survey of disposal site was conducted together with Swedish experts at 2011; –EU Project “Survey and Strategic Assessment of Georgian Radwaste Interims Storage and Disposal Facilities” was conducted at 2012–2013; –EU Project “Aim Conducting of Safety

Assessment of CSF and Disposal” was started at 2013. Generally speaking, RWMS should contain four major elements: legal basement, administrative structure, infrastructure for handling with radioactive waste, and financial system. Only some parts of above-mentioned elements are exist in Georgia now. RWMS should meet nine basic principles defined by IAEA. 

Martensitic transformations and shape memory effects in the Ti–43.2 wt.% Ta, Ti–50 wt.% Ta, and Ti–59.8 wt.% Ta alloys were studied. The alloys were preliminarily quenched after one hour annealing at 1000°C. The phase composition in the initial state was controlled radiographically. In the case of Ti–43.2 wt.% Ta, this was a¢¢-martensite, for Ti–50 wt.% Ta - a¢¢+(β) and β + (a¢¢) for the Ti–59.8 wt.% alloy Ta. The character of phase transformations was studied by differential calorimetry. Preliminary deformation by torsion. The shape memory effect was studied after setting the preliminary deformation, which was carried out in two ways in the torsion mode. In the first case, the sample was loaded in the temperature range Ms < T < As, the sample was pinched, and cooled to room temperature in the pinched state. In the second case, cooling after isothermal loading in the temperature range Ms < T < As occurred under the action of a constant applied load. For all alloys, the degree of shape recovery at initial deformation up to 4–5% was not lower than 90–98%. The study of reactive strain was carried out during heating to 800 ºС of alloy samples rigidly fixed at both ends. The maximum value of reactive strain for various degrees of initial deformation was achieved in the temperature range of 400–500°C. Their value at a preliminary deformation of 8-10% reached 350-450 MPa. The superelasticity of the alloys at room temperature at a strain of 4–5% increased from 60–70–% to 97–100% after four–five loading–unloading cycles. The damping capacity Ψ = 2πQ-1 (Q-1 internal friction) in the temperature range of reverse martensitic transformation was 13-23% for hertz and ~6% for kilohertz oscillation frequencies.

We studied inelastic effects in binary alloys Ti-25.9 wt.% Nb, Ti-29.8 wt.% Nb and Ti-33 wt.% Nb. The alloys were tempering after an hour of exposure at the temperature of the existence of β-austenite (950-1000 ° C) Tempering was fixing a¢¢- martensite in Ti–25.9 wt.%Nb, a¢¢+(β) in Ti–29.8 wt.%Nb and a¢¢+ β in Ti–33 wt.%Nb. The phase composition was controlled by X-ray diffraction by means of deformation. direct transformation - after isothermal loading of the sample at T > Ms, it was cooled to room temperature at a constant voltage. For strain values not exceeding 5%, the degree of shape recovery was not lower than 95-98%. Increasing of deformation wasreduced the rate of recovery. Measurement of reactive strain during heating (up to 800 °C) of specimens rigidly fixed at both ends showed maximum values of 400–450 MPa for all alloys at an initial strain degree of 8–10%. Superelasticity at room temperature after 5-6 cycles of loading-unloading increased (at a total deformation of about 4-5%) from 50 to 100% on average, for almost all alloys.

The damping ability of the alloys associated with the occurrence of the reverse martensitic a¢¢→ β transformation was studied by the method of a direct pendulum and an acoustic spectrometer. In the range of hertz frequencies, damping of vibrations by alloys varied from 10% to 20% and amounted to ~3% for the frequency of forced vibrations in the kilohertz range.

loading the samples at a temperature Td > Ms and subsequent cooling to room temperature under the applied load. Samples were heated by passing an electric current. The temperature Td was reached either by heating the samples from room temperature or by cooling after preheating to T >> Af. SME for all alloys, except for Ti–9.9Nb–10.0V, took place only upon cooling to Td from high temperatures. Upon heating from room temperature to Td, the SME in these alloys was weakly pronounced. The process of deformation and shape recovery for the Ti–5.1Ta–4.9Mo–4.9V alloy is shown in Fig. 1 (recording on a two-coordinate recorder). The obtained dependence of the shape memory effect on the degree of preliminary deformation for all the investigated alloys is shown in Fig.2. Four-component alloys seem to be the most promising. A characteristic difference of these alloys, in addition to high values of h, is the small width of the reverse martensitic transformation interval (Af – As » 50°) as compared to ternary alloys. The values of the reactive strains were also measured at various degrees of preliminary deformation. There was selected according to the degree of metastability of the β-phase for values of Kβ ~ (0.9 – 1.2). The alloys were tempering after an hour exposure at 1000°C. The initial phase composition corresponded to (α˝) or (α˝+ β). "

Doctoral Thesis Referee

Master Theses Supervisor

Doctoral Thesis Supervisor/Co-supervisor

Scientific editor of monographs in foreign languages

Scientific editor of a monograph in Georgian

Editor-in-Chief of a peer-reviewed or professional journal / proceedings

Review of a scientific professional journal / proceedings

Member of the editorial board of a peer-reviewed scientific or professional journal / proceedings

Participation in a project / grant funded by an international organization

Participation in a project / grant funded from the state budget

Patent authorship

Membership of the Georgian National Academy of Science or Georgian Academy of Agricultural Sciences

Membership of an international professional organization

Membership of the Conference Organizing / Program Committee

National Award / Sectoral Award, Order, Medal, etc.

Honorary title

Monograph

Handbook

Research articles in high impact factor and local Scientific Journals

Publication in Scientific Conference Proceedings Indexed in Web of Science and Scopus