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The data on changing of organic matter structure during composting cattle manure and plant waste mixtures are given. It was established that the content of humic matter and humic acids in substrates increased. The decrease of the content of the hydrolysable part of the substrate was mainly due to hard-hydrolysable and watersoluble substances. It was established that the increase of the content of total and mobile nitrogen and phosphorus and total potassium in the substrates is occurred. It was found that organic matter losses depended on the composition of mixtures and reached 17 % of its initial mass.

The question of the biological role of weakened electromagnetic fields (EMF) is relevant due to the fact that in modern life, organisms of varying degrees of complexity often face conditions in which the natural EMF can be shielded or distorted. And the study of the influence of ionizing radiation on life expectancy has been conducted for several decades in various laboratories around the world. The main component in determining the effects of radiation exposure is induced genetic instability, against the background of which it is possible to implement a variety of radiobiological reactions that lead to both stimulation and significant suppression of vital functions of the cell or body. In this regard, the aim of the study was to investigate the effect of moderate ferromagnetic shielding and 40 Gy X-ray radiation on the development of Drosophila melanogaster. Two series of experiments were carried out to achieve the goal. Initially, the nutrient medium prepared from yeast, sugar, semolina, propionic acid, water, and agar-agar was placed in the test tube. In groups there were 10 test tubes each, in which adult flies in number of 1 female and 1 male were placed. In the experiment, tubes with daily egg-laying were used (after the daily content of parent flies were removed from the tubes). Clutches were observed: from the appearance of the first pupae to the end of adults’ release. All groups of insects were kept in special thermoboxes (without light access). In the first series of the experiment the air temperature was 22 °C, in the second series of the experiment – 18 °C. The development of Drosophila melanogaster depends on t° air, with its decrease from 22 ° C to 18 ° C, the intensity of pupation of larvae and the yield of adults decreases by 45 % (p

Peculiarities of distribution, population density and spatial behavior of ermine in the winter season in the natural regions of Roztotchya and Nadsyannia have been studied. About 60 % of the district’s territory lies within the hilly region of Roztocko-Opil, in particular Roztocze, the other part belongs to Prykarpattia, namely the Nadsyan plain. Methods of tracking and accounting of traces on snow were used. Population density calculations were performed according to the updated formula Formozova. The results of research have shown that the ermine is a fairly common species on both the Roztoc Upland and the Nadsyan Plain. However, the habitats of this predator mostly cover aquatic habitats (67 %). The best stations are primarily the coastal strip of small rivers and streams. In second place in terms of the number of registered traces of the species is the border of forests and arable fields, or meadows (20 %). In large forests, the species is mostly registered on fellings and young forest crops (8 %). In fields more than 500 m away from forests and water bodies, ermine is rare (3 %). Occasionally ermine is registered in settlements – near buildings (2 %). The highest population density of the species was observed in 2010 (8 individuals / 1000 ha). The lowest rates were registered in 2012 (2 individuals / 1000 ha). On average, the amplitude of fluctuations in ermine population density for 10 consecutive years reached 4 times the value. However, in coastal stations, the difference between the extreme indicators was 6 times (2–12 individuals / 1000 ha). The length of the daily course of ermines in winter is from 200 m to 4.5 km, on average 1.2 km. The average size of a single area of ​​the animal along the shores of reservoirs is 15–20 hectares, in the depths of the forest can be 100 hectares or more. Individual areas of males are slightly larger than females and are often superimposed on them. Instead, individual areas of males or females that live nearby almost never overlap. Some ermines can lead a nomadic lifestyle. The species is often active during the light period of the day.

Presented are investigations of in situ preparation of composite nanopowders of AlN, GaN, and, optionally, solid solution Al0.5Ga0.5N, which were used in no-additive, high-pressure/high-temperature sintering. Two precursor synthesis pathways and two nitridation temperatures afforded nanopowders containing both (i) mixed AlN and GaN and (ii) such AlN and GaN admixed with Al0.5Ga0.5N as well as (iii) reference individual AlN and GaN. The applied sintering temperatures were either to preserve powder nanocrystallinity (650 °C) or promote crystallite growth and sintering-mediated Al0.5Ga0.5N formation (1000 °C). One specific route led to the novel nanoceramics of Al0.5Ga0.5N. The powders and nanoceramics were characterized by XRD, FT-IR, SEM/EDX, 27Al/71Ga MAS NMR, BET/BJH surface areas, and helium densities. Vicker’s hardness tests confirmed many of the sintered composites and individual nitrides having high hardness comparable with monocrystalline AlN and GaN. Formation of pure Al0.5Ga0.5N nanoceramics was associated with closed pore evolution and had a detrimental effect on hardness.

Zr-based metallic glasses are prepared by quenching supercooled liquid under pressure. These glasses are stable in ambient conditions after decompression. The High Pressure Quenched glasses have a distinct structure and properties. The pair distribution function shows redistribution of the Zr-Zr interatomic distances and their shift towards smaller values. These glasses exhibit higher density, hardness, elastic modulus, and yield stress. Upon heating at ambient pressure, they show volume expansion and distinct relaxation behavior, reaching an equilibrated state above the glass transition. These experimental results are consistent with an idea of pressure-induced low to high density liquid transition in the supercooled melt.

The dependency of the surface free energy (SFE) of diamond nanocrystals on particle size was studied by means of molecular dynamics (MD) and DFT simulations. It was demonstrated how to avoid the ambiguities in calculating the surface area of very small crystallites by expressing the particle size in terms of the number of atoms which we called the number of atoms convention (NAC) rather than in units of length. The NAC method was applied to a set of models terminated with either (100) or (111) crystal faces. The MD simulations were done for two widely used potentials, i.e. Tersoff and AIREBO. Both potentials show appreciable changes in surface free energy with decreasing crystal size but in opposite directions. In the limit of an infinite crystal both tested potentials give the energy of the (100) surface to be more than two times higher than that of the (111) surface. Also the absolute figures calculated from the AIREBO potential are twice larger than those from the Tersoff potential. DFT simulations of the selected small particles confirmed the MD calculations based on the AIREBO results for the (111) surface but for the (100) surface the values were considerably smaller.

N-phenyl- and N-octyl-substituted derivatives of polyhexamethylene guanidine hydrochloride were synthesized and their antimicrobial activity against nosocomial infections was determined.

On the basis of previously developed rheodynamic models of high-temperature SHS‑compaction, a theoretical analysis of the process of backward pressing with the active action of external friction force was carried out. It is shown that in this version of extrusion external friction is a useful technological effect, which allows to obtain a uniform distribution of density over the volume of the pressing material. Analytical relationships have been obtained for calculating the characteristic pressing time and stress distribution.

Spherical and polyhedral diamond nanocrystals grains terminated by low-index atomic planes (100), (110), and (111) were examined using Molecular Dynamics (MD) simulations. Real space methodology (PDF analysis) was applied for examination of the internal structure of diamond nanograins through performance of virtual diffraction experiments for MD simulated models. The effect of the grain size on, (1), the bond length in the nearest neighbor coordination, (2), the overall lattice parameter, and (3), a presence of internal strains in individual grains were examined. It is shown that, (a), graphite-like bonds are present in the first 2–3 atomic layers, depending on the surface type, (b) in 2–3 nm grains the overall value of alp is about 0.5% larger than the reference diamond lattice parameter and it goes down to the reference diamond lattice in grains of about 10 nm in size, (c), in individual spherical grains the so called “density waves”, propagating from the grain center towards the surface, are present. In the “general model” of nanodiamond structure the number of density maxima is the same for grains with sizes between 2.5 and 10 nm, but the amplitude of the waves diminishes with an increase in the grain size.

The article is devoted to the solution of key issues arising in the course of practical implementation of the artificial intelligence system elements. Based on the need to distribute tasks among several developers and ensure scalability, the structure of the system, the programming language and the data transfer protocol of the program modules were determined. The structure of the software package is conditioned by the requirement to modify and expand its capabilities by connecting additional software modules or completely replacing them. A refined algorithm for receiving and processing a command from the external environment is presented. The choice of the programming language is based on the availability of already developed libraries that solve the tasks of artificial intelligence, as well as the need to ensure cross-platform software. The choice of the programming language is based on the availability of already developed libraries that solve the tasks of artificial intelligence, as well as the need to ensure cross-platform software. The choice of the protocol for exchanging data between the individual program modules of the system was carried out proceeding from the need to transfer data of arbitrary size.

In the course of the study, 124 case records of patients with epileptic seizures (cryptogenic epilepsy) were analyzed. Diagnosis was established based on a typical clinical presentation, anamnesis, electroencephalogram (EEG) dynamics, and/or video EEG monitoring in the 10-hour format. Group I comprised 36 patients with normal liquor-cranial indexes ranging from 1.6 to 3.6 with an average value of 2.1±0.2; these patients received standard multicomponent therapy during the hospitalization and at the outpatient-polyclinic stage. Group II comprised 42 patients who had liquor-cranial indexes below the lower limit of normal ranging from 0.8 to 1.2 with an average value of 1.0±0.1; these patients also received therapy for primary diagnosis according to standard therapy scheme, which was identical to that in group I. Patients of group III (main group, n=46) had liquor-cranial indexes below physiological norm (from 0.8 to 1.2 with an average value of 0.9±0.1) and received modified therapy. Two-year follow up study showed that more severe cognitive deficit developed in patients with low cerebrovascular indexes receiving standard therapy compared to patients with low cerebrovascular indexes who received modified therapy. The absence of significant differences between patients of group I and III suggest that timely correction of increased intracranial pressure allowed to prevent significant aggravation of pathopsychological characteristics, loss of short-term and long-term memory, and overall cognitive function decline.

The $p\text{\ensuremath{-}}T$ conditions of the solid-solid phase transition from the wurtzite to rocksalt structure in GaN are determined both experimentally and by ab initio calculations. Experimental evaluation was based on the x-ray absorption measurements in a laser-heated diamond anvil cell. At 300 K, the transition was observed near 47 GPa. At lower pressures, the wurtzite to rocksalt transition has been induced by high temperature: 1420 K at 42 GPa and about 2100 K at 37 GPa. Thus the slope of the wurtzite-rocksalt borderline could be evaluated as negative and nonlinear. On the part of the theory, the $p\text{\ensuremath{-}}T$ borderline was determined from a comparative analysis of the temperature dependences of the Gibbs potential of the wurtzite and rocksalt structures for different pressure. The Gibbs potentials were calculated within the quasiharmonic approximation and the self-consistent phonon approach. The results obtained with the self-consistent phonon approach show that the inclusion of the anharmonic phonon effects is indispensable to obtain a very good agreement with the experimental data. Possible consequences of the observed anharmonicity for the still unknown melting behavior of GaN are discussed. In particular, it is suggested that the melting temperature of the rocksalt-GaN, at pressure around 37 GPa, is not much higher than 2100 K.

The article systematizes the accumulated experience of conducting interviews for the mental health of adolescents in conflict with the law. Mental health of adolescents is considered as a basic condition for development and well-being. Children in conflict with the law are traditionally regarded as a threat to society, social isolation and stigma are planned. However, the international practice of working with children in conflict with the law suggests revising this approach and assessing the conditions under which conflict with the law became possible. A big role in this approach is the problem of assessing the needs and needs of the child. Mental health, as the basic basis of evaluation, occupies a significant place. Taking into account the role of the assessment of mental health to address issues of the child's future fate, the risks of repeated conflicts with the law, planning of rehabilitation and rehabilitation programs, the question of methods and conditions for obtaining data on mental health becomes urgent. The role of mental health promotion strategies for minors involved in the justice system is explained as a way to improve children's social skills, change behavior and involve their families in treatment and education plans. The authors examined the specifics of conducting a comprehensive assessment of mental health among adolescents in conflict with the law to identify the best forms of intervention. The methodology of the study, the features of preparing the questionnaire for the interview, is substantiated. Specific moments of organization of interviews and training of interviewers are indicated. Based on the study, the authors suggest activities that will help to get teenagers help in the field of mental health.Key words: mental assessment, mental health, help, intervention, interview, adolescents in conflict with the law.

Presented is a study on the preparation, via original precursor solution chemistry, of intimately mixed composite nanocrystalline powders in the system gallium nitride GaN–titanium nitride TiN, atomic ratio Ga/Ti = 1/1, which were subjected to high-pressure (7.7 GPa) and high-temperature (650, 1000, and 1200 °C) sintering with no additives. Potential equilibration toward bimetallic compounds upon mixing of the solutions of the metal dimethylamide precursors, dimeric {Ga[N(CH3)2]3}2 and monomeric Ti[N(CH3)2]4, was studied with 1H- and 13C{H}-NMR spectroscopy in C6D6 solution. The different nitridation temperatures of 800 and 950 °C afforded a pool of in situ synthesis-mixed composite nanopowders of hexagonal h-GaN and cubic c-TiN with varying average crystallite sizes. The applied sintering temperatures were either to prevent temperature-induced recrystallization (650 °C) or promote crystal growth (1000 and 1200 °C) of the initial powders with the high sintering pressure of 7.7 GPa having a detrimental effect on crystal growth. The powders and nanoceramics, both of the composites and of the individual nitrides, were characterized if applicable by powder XRD, SEM/EDX, Raman spectroscopy, Vicker’s hardness, and helium density. No evidence was found for metastable alloying of the two crystallographically different nitrides under the applied synthesis and sintering conditions, while the nitride domain segregation on the micrometer scale was observed on sintering. The Vicker’s hardness tests for many of the composite and individual nanoceramics provided values with high hardness comparable with those of the individual h-GaN and c-TiN ceramics.

NanoPDF64 is a tool designed for structural analysis of nanocrystals based on examination of powder diffraction data with application of real-space analysis. The program allows for fast building of models of nanocrystals consisting of up to several hundred thousand atoms with either cubic or hexagonal close packed structure. The nanocrystal structure may be modified by introducing stacking faults, density modulation waves (i.e. the core–shell model) and thermal atomic vibrations. The program calculates diffraction patterns and, by Fourier transform, the reduced pair distribution functions G(r) for the models. Experimental G(r)s may be quantitatively analyzed by least-squares fitting with an analytical formula.

The resistance of bacteria to the disinfectants used is one of the pressing health problems that need to be addressed in order to prevent the formation and spread of resistant strains. This leads to a sharp decrease in the effectiveness of anti-epidemic measures and contributes to maintaining a high level of morbidity. In the context of the growing incidence of HAIs, their polyetiology, the large adaptive potential of opportunistic microorganisms, and the growing resistance to antimicrobial drugs, it is necessary to search for new or modify the corresponding substances of plant or synthetic origin that have antimicrobial action and are used as antimicrobial agents. One of the representatives of this class of compounds are polyguanidines, characterized by high antimicrobial activity and low toxicity. Due to the high reactivity of the guanidine group, as well as the ease of synthesis and the relative availability of raw materials, N-phenyl- and N-octyl-substituted derivatives of polyhexamethylene guanidine hydrochloride were obtained by melt polycondensation, their molecular weight characteristics were determined, and the structure was investigated by IR spectroscopy. An earlier study of the acute toxicity of polyhexamethylene guanidine hydrochloride derivatives after a single oral intake of drugs into the body of laboratory animals (white mice) made it possible to establish the following LD50 values: polyhexamethylene guanidine hydrochloride - 850.0 ± 112.02 mg / kg; N-phenyl-substituted polyhexamethylene guanidine hydrochloride - 1399.9 ± 120.51 mg / kg; N-octyl-substituted polyhexamethylene guanidine hydrochloride - 1150.0 ± 137.40 mg / kg. The obtained values, according to the tabulation of hazard classes, allow the synthesized derivatives to be classified into the fourth hazard class and open up the possibility of using disinfectants as active components. The evaluation of the antibacterial properties of the samples was carried out by the method of serial dilutions in agar on hospital strains of bacteria and fungi isolated from the biomaterial of patients of the Republican Clinical Hospital named after N.A. Semashko, according to the clinical guidelines "Laboratory diagnosis of community-acquired pneumonia" 2014; "Bacteriological analysis of urine" 2014; "Determination of the susceptibility of microorganisms to antimicrobial drugs" 2015 It was found that N-substituted derivatives exhibit a greater antimicrobial effect in comparison with an unsubstituted polymer. The most sensitive to all the drugs presented are the yeast-like fungi Candida albicans (No. 2495) (complete suppression), as well as methicillin-resistant St. aureus (no. 2544), and the substituted samples almost completely suppress its growth. The most resistant strains are P. aeruginosa (No. 2281), A. Baumannii (No. 2806) and K. Pneumoniae (No. 3023), the percentage of reduction of these bacteria under the action of substituted samples does not exceed 41%, which is explained by their multi-resistance.

Semiconducting polymers are promising materials for photocatalysis, batteries, fuel applications, etc. One of the most useful photocatalysts is polymeric carbon nitride (PCN), which is usually produced during melamine condensation. In this work, a novel method of obtaining a PCN nanocomposite, in which PCN forms an amorphous layer coating on oxide nanoparticles, is presented. Microwave hydrothermal synthesis (MHS) was used to synthesize a homogeneous mixture of nanoparticles consisting of 80 wt.% AlOOH and 20 wt.% of ZrO2. The nanopowders were mechanically milled with melamine, and the mixture was annealed in the temperature range of 400&ndash, 600 &deg, C with rapid heating and cooling. The above procedure lowers PCN formation to 400 &deg, C. The following nanocomposite properties were investigated: band gap, specific surface area, particle size, morphology, phase composition, chemical composition, and photocatalytic activity. The specific surface of the PCN nanocomposite was as high as 70 m2/g, and the optical band gap was 3 eV. High photocatalytic activity in phenol degradation was observed. The proposed simple method, as well as the low-cost preparation procedure, permits the exploitation of PCN as a polymer semiconductor photocatalytic material.

Presented is a study on the original preparation of individual and in situ intimately mixed composite nanocrystalline powders in the titanium nitride-aluminum nitride system, Ti:Al = 1:1 (at.), which were used in high pressure (7.7 GPa) and high temperature (650 and 1200 °C) sintering with no binding additives for diverse individual and composite nanoceramics. First, variations in precursor processing pathways and final nitridation temperatures, 800 and 1100 °C, afforded a pool of mixed in the nanosized regime cubic TiN (c-TiN) and hexagonal AlN (h-AlN) composite nanopowders both with varying average crystallite sizes. Second, the sintering temperatures were selected either to preserve initial powder nanocrystallinity (650 °C was lower than both nitridation temperatures) or promote crystal growth and recrystallization (1200 °C was higher than both nitridation temperatures). Potential equilibration towards bimetallic compounds upon solution mixing of the organometallic precursors to nanopowders, monomeric Ti[N(CH3)2]4 and dimeric {Al[N(CH3)2]3}2, was studied with 1H and 13C NMR in C6D6 solution. The powders and nanoceramics, both of the composites and individual nitrides, were characterized if applicable by powder XRD, FT-IR, SEM/EDX, Vicker’s hardness, and helium density. The Vicker’s hardness tests confirmed many of the composite and individual nanoceramics having high hardnesses comparable with those of the reference h-AlN and c-TiN ceramics. This is despite extended phase segregation and, frequently, closed microsized pore formation linked mainly to the AlN component. No evidence was found for metastable alloying of the two crystallographically different nitrides under the applied synthesis and sintering conditions. The high pressure and high temperature sintering of the individual and in situ synthesis-mixed composite nanopowders of TiN-AlN was demonstrated to yield robust nanoceramics.

Following our previous brief communication the carbonization of halogenated adamantanes C10H14Br2 and C10H15Cl under high pressure with the aim to produce nanodiamonds have been studied in details. A fixed pressure of 8 GPa and temperatures up to 2000 K were applied. Carbonization behavior of both precursors is very similar and starts in range of 900–1000 K with formation of about 1–2 nm diamond nanocrystals. With increasing process temperature the size of obtained nanodiamonds slowly grows up to tens of nanometers at 2000 K. The observed behavior provides favorable conditions for the synthesis of the nanodiamonds of the precisely controlled crystal size. Raman spectroscopy, X-ray diffraction and high resolution transmission microscopy were used to monitor the phase composition of the samples and the crystal size of nanodiamonds. Lattice parameter of nanodiamonds, calculated by using the Rietveld analysis of the X-ray diffraction patterns, increases by up to 2–3% as an average crystallite size decreases to the minimal value of 1–2 nm. Based on the experimental results and density functional theory calculations, extremely high increase in the lattice parameter of nanodiamonds is interpreted in terms of the strain exerted on the nanocrystals due to diamond surface reconstruction, particularly on the (110) face. Lowering of the crystal size is accompanied by the red-shift and broadening of the diamond Raman line. The effects are explained in terms of the crystal lattice expansion and the phonon confinement model.

The effect of interaction of low-index atomic planes, (100), (110), and (111) terminating CdSe platelet nanocrystals is examined using molecular dynamics (MD) simulations. Asymmetry of the environment of atoms at the end surface layers leads to anisotropic deformation of the cubic lattice and to a relative shift of Cd and Se sub-lattices. Interference of distortions of the crystal lattice originating at the terminal surfaces leads to changes of symmetry of the CdSe lattice in the whole sample volume. In the models, 2-3 nm thick, for all types of surfaces under examination, the initial cubic lattice symmetry gets lost in the whole sample volume. Graphical abstractᅟ.

The results of molecular dynamics (MD) simulations of CdSe crystals terminated by low-index atomic planes, (100), (110) and (111), are presented. The effect of the crystal termination on the atomic arrangement (interatomic distances) at the surface and underneath the surface is examined. It is shown that the crystal lattice is distorted in lateral and normal directions to the depth of up to about 2 nm from the surface. The exact characteristic of the changes of interatomic distances is specific to the type of the atomic plane terminating the crystal lattice. At some surfaces, the very last monoatomic layer loses the long-range ordering and becomes quasi amorphous. The atoms group into randomly distributed pairs or short linear groups.

To evaluate the effect of modified therapy on the course of epilepsy in patients with the low cerebral-spinal-fluid-cranial (CSF-cranial) index.One hundred and twenty-four patients with cryptogenic epilepsy were prospectively analyzed. Group I consisted of 36 patients with a normal volume of reserve cerebrospinal fluid and a level of the CSF-cranial index within the physiological norm (from 1.2 to 3.6), who received standard therapy. Group II consisted of 42 patients with a small volume of reserve cerebrospinal fluid spaces and a CSF-cranial index lower than the physiological norm (from 0.8 to 1.2), who received standard therapy. Group III (n=46) was characterized by a small volume of reserve cerebrospinal spaces and a CSF-cranial index lower than the physiological norm. Patients of this group received modified therapy.Normalization of the level of intracranial pressure in patients with a low cerebrovascular index reduced the frequency of epileptic seizures. After one year follow-up, the proportion of patients with very frequent seizures decreased by 25.3%, with frequent seizures by 23.9%, after 2 years by another 33.1 and 15.7%, respectively. A correlation was found between the frequency of seizures and the level of intracranial pressure (G=0.24, p=0.043).Цель исследования. Оценить влияние модифицированной терапии на течение эпилепсии у больных с низким цереброспинально-жидкостно-краниальным индексом (ЦСЖКИ). Материал и методы. Проанализированы истории болезни 124 пациентов с криптогенной эпилепсией. В 1-ю группу вошли 36 пациентов с нормальным объемом резервных ЦСЖ-пространств и уровнем ЦСЖКИ в пределах физиологической нормы (от 1,2 до 3,6), которым проводили стандартную терапию. Во 2-ю группу включили 42 пациента, у которых отмечен малый объем резервных ЦСЖ - пространств и ЦСЖКИ был меньше физиологической нормы (от 0,8 до 1,2), а терапия эпилепсии была идентична таковой в 1-й группе. Больные 3-й группы (n=46) характеризовались малым объемом резервных ЦСЖ-пространств, ЦСЖКИ менее физиологической нормы (от 0,8 до 1,2) и модифицированной терапией. Результаты и заключение. Нормализация уровня внутричерепного давления у пациентов с низким ЦСЖКИ позволила снизить частоту эпилептических приступов. Через 1 год наблюдения и лечения доля пациентов с очень частыми приступами снизилась на 25,3%, с частыми - на 23,9%, через 2 года - еще на 33,1 и 15,7% соответственно. Выявлена корреляционная связь между частотой приступов и уровнем внутричерепного давления (G=0,24; р=0,043).

In the reported work, the combination of severe plastic deformation (SPD) and annealing under high hydrostatic pressure was used to enhance the ductility whilst maintaining the high mechanical strength possessed by the nanostructured 316LVM stainless steel. The nanostructure was obtained by a multi-step hydrostatic extrusion process to a total true strain of 1.8. This process produced a microstructure consisting of nanotwins and shear bands. The extruded samples were annealed at 700 and 900 °C for 10 min under atmospheric or hydrostatic pressures of 2 or 6 GPa. The resulting microstructures were examined using TEM and FIB techniques. The microstructural observations and X-ray measurements were used to estimate the crystallite sizes. The mechanical properties were determined by microhardness and tensile tests. It was established that annealing under high pressure improved the ductility of the material whilst retaining its high ultimate tensile strength.

Nanosize diamond–silicon carbide composites have been sintered at high temperatures and a fixed pressure of about 8 GPa. Crystallite size, densities of stacking faults and dislocations in diamond and silicon carbide crystallites are determined by X-ray diffraction profile analysis. It has been shown that crystallite sizes increase while population of stacking faults and dislocations decrease with temperature increasing from 1820 °C to 2320 °C. These conclusions indicate that to produce composites with small residual stresses the sintering process should be conducted at the highest possible temperatures.

The ammonothermal technique was used to obtain GaN powders doped with various transition metal ions—Mn, Fe, Cr. The procedure of ammonothermal growth and morphology, structural, magnetic and optical investigations of magnetic GaN is described. The largest solubility limit ( x 2+ centers are responsible for the paramagnetic behavior of GaMnN. X-ray diffraction study of GaMnN revealed presence of different Mn x N y compounds, in particular ferromagnetic Mn 4 N which may be the source of additional ferromagnetic contribution. The results show substantial difficulties to obtain hole induced ferromagnetism in GaMnN. Mn reduces the luminescence efficiency of ammonothermal GaN. In the case of Fe doping we are dealing with a spectrum of different Fe centers. Ammonothermal GaN:Cr is ferromagnetic but its origin is unrecognized yet.

GaN nano-ceramics were analyzed using transmission electron microscopy (TEM), showing that these ceramics are characterized by highly disoriented grains of the linear size of 100–150 nm. These GaN ceramics were used as substrates for GaN epitaxy in standard MOVPE conditions. For the comparison, MOVPE GaN layers on silicon substrates were grown using similar conditions. It is shown that MOVPE growth of GaN layers is highly anisotropic for both cases. However, the disorientation of the highly mismatched GaN layer on silicon is different from that characterizing GaN layer deposited on the ceramic substrate. In the latter case the disorientation is much higher, and three dimensional in nature, causing creation of polycrystalline structure having large number of the dislocations. In the case of the GaN layer grown on the silicon substrate the principal disorientation is due to rotation around c-axis, causing creation of mosaic structure of edge dislocations. Additionally, it is shown that the typical grain size in AlN nucleation layer on Si is smaller, of order of 20 nm. These two factors contribute to pronounced differences in later stage of the growth of GaN layer on the ceramic. Due to high growth anisotropy an appropriately thick GaN layer can, eventually, develop flat surfaces suitable for construction of optoelectronic and electronic structures. As shown by the TEM data, this can be achieved only at the cost of creation of the relatively large density of dislocations and stacking faults. The latter defects were not observed for the GaN growth on Si substrates. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The structure of a nanodiamond powder with an average grain size of 5 nm was investigated using large-Q neutron diffraction. Both Bragg scattering and PDF analysis were employed. The effect of annealing under vacuum at temperatures up to 1200 °C was studied. The studies lead to a tentative model of nanocrystalline diamond, where the core with a perfect diamond lattice is surrounded by a shell of compressed diamond lattice, and this core–shell structure is enveloped in a non-diamond carbon. The non-diamond envelope of nanograins, a “gas-like” carbon, is stable up to 1000 °C and transforms into a graphite phase (an onion-type structure) at about 1200 °C. The amount of non-crystalline carbon in the powder annealed below 1000 °C is about 10%. In the sample annealed at 1200 °C a graphite-type carbon, with a total of about 15% of sp2 bonds is formed.

Thermal atomic motions of nanocrystalline Sic were characterized by two temperature atomic factors B(sub core), and B(sub shell). With the use of wide angle neutron diffraction data it was shown that at the diffraction vector above 15A(exp -1) the Wilson plots gives directly the temperature factor of the grain interior (B(sub core)). At lower Q values the slope of the Wilson plot provides information on the relative amplitudes of vibrations of the core and shell atoms.

Herein, are reported studies of various experimental conditions aimed at optimizing the Aerosol-Assisted Vapor Phase Synthesis (AAVS) of GaN powders. In general, the process utilizes affordable oxygen-bearing gallium precursors in aqueous/methanol solutions to initially prepare nano-sized GaN x O y powders of spheroidal morphology. Subsequent pyrolysis of the GaN x O y intermediate in a NH 3 atmosphere converts the powders to sub-micron, crystalline GaN powders that usually contain some residual oxygen. The application of appropriate solvents, e.g., methanol, in the aerosol powder generation stage and the use of pyrolysis temperatures in the range 900-1000 °C may improve both the extent of nitridation and, to certain degree, the control over average particle sizes. The characteristics of the AAVS-produced materials are compared with those for bulk GaN powders obtained by direct nitridation of commercial gallium oxide.

X-ray and neutron diffraction experiments were performed on nanocrystalline SiC with the average grain diameters of 7, 12, and 16 nm subjected to isostatic pressure. Under pressure the interatomic distances undergo a complex, non-monotonic changes which were correlated with the compression of the SiC lattice determined from the Bragg scattering. The results indicate the presence of non-uniform distribution of stresses between the interior and surface shell of the nanograins. The present results lend a strong support to the concept of a core-shell model of nanocrystals.

The effect of the presence of surface strains on the apparent lattice parameters (alp) obtained experimentally for nanocrystalline SiC is discussed. The alp values were determined for two kinds of powders with an average crystallite size of 11 nm and related sintered samples. The measurements were done in a wide range of the diffractions vector up to Q = 12 A −1 , allowing for evaluation of the internal pressure in the grains. Based on in situ high-temperature measurements, the thermal expansion coefficient and overall temperature factor B T were evaluated. It is shown that while the thermal expansion coefficient changes very little upon sintering, there is a large difference in the amplitude of the atomic oscillations between powders and sintered SiC reflected in a difference between respective Debye temperatures. It is concluded that the overall thermal properties of nanocrystals are determined by two components: thermal properties of the crystallite surface and its interior. The atoms at the surface vibrate much stronger than those in the bulk, and their behavior is strongly affected by the crystallite’s environment.

Application of in situ high pressure powder diffraction technique for examination of specific structural properties of nanocrystals based on the experimental data of SiC nanocrystalline powders of 2 to 30 nrn diameter in diameter is presented. Limitations and capabilities of the experimental techniques themselves and methods of diffraction data elaboration applied to nanocrystals with very small dimensions (< 30 nm) are discussed. It is shown that due to the complex structure, constituting a two-phase, core/surface shell system, no unique lattice parameter value and, consequently, no unique compressibility coefficient can satisfactorily describe the behavior of nanocrystalline powders under pressure. We offer a tentative interpretation of the distribution of macro- and micro-strains in nanoparticles of different grain size.

The applicability of standard methods for the evaluation of powder diffraction data of nano-size crystallites is analyzed. Based on theoretical considerations, it is shown that deviations of the structure of small particles from the Bragg approximation on an infinite crystal lattice leads to significant differences in the diffraction patterns, which may lead to an erroneous interpretation of the experimental results. An alternative evaluation of the diffraction data of nano-particles, based on the so-called "apparent lattice parameter", alp , is proposed. Based on this method, it is shown that real nano-crystals constitute a complex, heterogeneous multi-phase structure.

Fundamental limitations, with respect to nanocrystalline materials, of the traditional elaboration of powder diffraction data like the Rietveld method are discussed. A tentative method of the analysis of powder diffraction patterns of nanocrystals based on the examination of the variation of lattice parameters calculated from individual Bragg lines (named the “apparent lattice parameter”, alp) is introduced. We examine the application of our methodology using theoretical diffraction patterns computed for models of nanocrystals with a perfect crystal lattice and for grains with a two-phase, core-shell structure. We use the method for the analysis of X-ray and neutron experimental diffraction data of nanocrystalline diamond powders of 4, 6 and 12 nm in diameter. The effects of an internal pressure and strain at the grain surface are discussed. The results are based on the dependence of the alp values on the diffraction vector Q and on the PDF analysis. It is shown, that the experimental results lend a strong support to the concept of a two-phase structure of nanocrystalline diamond.

High-pressure in situ diffraction studies were performed up to 8 GPa in a cubic anvil cell MAX80 (Station F2.1) and up to 45 GPa in a Diamond Anvil Cell (DAC-Station F3 at HASYLAB, Hamburg). A series of nanocrystals of SiC with grain sizes ranging from 2 nm to several μm were examined in non-hydrostatic conditions by pressing pure powders. A new method of evaluation of powder diffraction data measured at high pressures is presented. This method is based on quantitative evaluation of asymmetry of Bragg reflections where each peak is described as a combination of two reflections of two similar crystallographic phases having different compressibilities. The measured changes of the lattice parameters calculated for split Bragg reflections were used for determination of the pressure gradient which occurs across the grain boundaries in the compressed materials. A model of the strain induced in compacts of pure powders under high pressures is proposed. The model accounts for the presence of two phases: a volume phase corresponds to cores of individual grains which are surrounded by a surface phase which is formed of free surfaces in loose powders and of grain boundaries in solids. Due to extreme hardening of the boundaries under non-hydrostatic pressure conditions, the effective pressure in the interior of the grains is much lower than the applied external pressure. It is suggested that additional ‘hardening’ of the grain boundaries results from the presence of dislocations which are generated at the surface of the grains. The actual gradient of the pressure depends on the size of the grains, and also on the method of synthesis of the materials.

Using a new methodology of elaboration of PDF data (G(r) function), which is based on the analysis of individual inter-atomic distances (ri), a function describing differences between average inter-atomic distances in CdSe nanograins derived experimentally and those in the parent bulk crystal was determined. Based on that methodology a unique atomic architecture of CdSe QDs is proposed. The results show that a good knowledge about the grain surface of nanocrystals alone may be insufficient for understanding the nanomaterials properties, and that the real atomic structure of the interior of nanograins is of importance as well.

The structure of nanocrystalline diamond was approximated by spherical nanograins assuming that the grain core with a perfect crystal lattice is surrounded by a sequence of shells with (essentially) identical atomic architecture but with altered density. We call such a model a nanocrystal with density modulated waves. To examine the effect of density modulation present in nanograins, we built atomistic models of nanodiamond grains and compared the average values of inter-atomic distances calculated for the grains with density waves to those calculated for grains with the perfect, diamond crystal lattice. We show that the atomic structure of nanodiamond can be best described by a model where, between the inner core and the surface layer, three density waves with intermittent compressive and tensile strains exist. The sequence of the density waves is preserved in all examined nanodiamond samples without regard to chemical treatment and vacuum annealing (at up to 1200°C).

The present work presents the results of mathematical modeling of deformation and thermal processes of compaction of viscous compressible materials. An analytical solution of the problem of one-sided compression and extrusion of powder materials is found which enables us to establish different regimes of compaction and extrusion and to find criterial conditions for their realization at a qualitative level. The numerical analysis of the influence of the nonunifomity of the thermal regime and the conditions of heat transfer on the regularities of compaction nd extrusion of the materials is performed. It is shown how the models developed facilitate the solution of practical problems of producing the concrete items.

Disordering in SiC is analyzed both theoretically and experimentally. Classification of the stacking faults into (i) intrinsic, (ii) twin-like and (iii) extrinsic faults is proposed. This classification correlates well with distinct diffraction effects, characteristic for specific faults. Based on proposed classification, the disordering in SiC β-powders obtained by SHS method (self-propagating high-temperature synthesis) is analysed both qualitatively and quantitatively. It is shown that in the β-powders a single cubic domain has an average size of approx. 55 Si–C double layers. Those domains separated by intrinsic faults (≈80%) form several hundred layers large blocks which are separated from each other by twin-like (≈5%) and/or extrinsic faults (≈15% of total number of stacking faults).

TiN nanopowders synthesized by the application of an anaerobic "imide" route and aerosol synthesis with 5 and 26 nm average size were examined by in situ diffraction at high pressure up to 6 GPa and high temperature up to 800 o C. Overall compressibilities and thermal expansion coefficients were determined for the examined pressure and temperature intervals. Nanocrystals of TiN show core-shell type structure where elastic properties of interior and surface shell are different; surface is softer and shows larger thermal expansion than crystalline TiN. Core-shell model was confirmed by analysis of large Q powder diffraction at room temperature with application of alp-Q and PDF analysis.