ENDOR study of irradiated tooth enamel

γ- and x-irradiated tooth enamel has been studied by EPR and ENDOR. Radiation-induced EPR spectrum of tooth enamel was found to be a superposition of signals with dominant contribution determined by CO₂- radicals. Two types of these radicals were observed: ordered and disordered centers. EPR spectra of both CO₂- centers are described by axial g-tensor with g = 1.9975 and g ⊥= 2.0021 with g || c. The ENDOR spectrum of unannealed enamel powder consists of a singlet at Larmor frequency of ³¹P nuclei and doublet at Larmor frequency of ¹H nuclei. Samples annealing at T = 200-250 ⁰C resulted in the destruction of disordered centers and appearence of superhyperfine structure of ENDOR spectra. Its analysis with advanced the powder ENDOR theory allows to determine the superhyperfine constants and to find for the first time that the ordered CO₂- radical is located in B sites (phosphorous position) of bioapatite lattice. This substitution is accompanied by the shift of the nuclei of the first ³¹P shell towards the defects by 0.04 nm and the formation of the OH vacancy in the nearest radical surroundings

Training of Teachers of Professional Training in Food Technologies in Conditions of Intensification of Modern Production

У статті розглядаються теоретико-методичні аспекти підготовки педагогів професійного навчання з харчових технологій в умовах інтенсифікації сучасного виробництва. Розглядається необхідність оновлення змісту підготовки педагогів професійного навчання з харчових технологій в умовах інтенсифікації виробництва навчання у вищих навчальних закладах. В сучасному суспільстві найчастіше застосовуються якісні чинники розширення виробництва, такі як підвищення продуктивності праці, вдосконалення діючих виробничих основних фондів, збільшення випуску продукції при менших витратах всіх ресурсів і ін. До інтенсифікації виробництва сучасного штовхає конкуренція, яка змушує виробників для отримання більшої, та й нормального прибутку знижувати витрати та підвищуючи продуктивність праці. Інтенсифікація сучасного виробництва приводить не тільки до економії праці, а і до економії всіх ресурсів: трудових, матеріальних, енергетичних, природних, фінансових та інших. Перспектива будь-якого виробництва лежить в площині впровадження чогось нового, нового товару, нової технології, нового обладнання, нової організації праці і так далі. В іншому випадку в умовах конкуренції і досить високому рівні розвитку продуктивних сил домогтися гарних успіхів неможливо. Підвищення продуктивності праці не можливе без оновлення застарілого обладнання, зміни технологій, застосування більш досконалої організації праці та нових матеріалів. Інформаційний вибух і сучасні темпи зростання наукової інформації, яку потрібно встигнути передати студентам за час навчання, спонукають викладачів шукати вихід з положення за рахунок нових педагогічних прийомів Інтенсифікація сучасного виробництва мотивує до зміни підходів у навчальному процесі підготовки фахівців професійної освіти. Перед сучасним педагогом професійного навчання стоїть задача активного пошуку новітніх, більш інтенсивних методів, форм і засобів навчання, щоб розвивати у студентів пізнавальну активність. Тому створення проблемних ситуацій у процесі підготовки педагогів професійного навчання є запорука підвищення ефективності навчання в умовах інтенсифікації сучасного виробництва [6].The article deals with theoretical and methodical aspects of the training of teachers of professional training in food technologies in the conditions of intensification of modern production. The necessity of updating the contents of the training of teachers of professional training in food technologies in the conditions of intensification of training production in higher educational institutions is considered. In modern society, high-quality factors of production expansion, such as increasing labor productivity, improving existing operating fixed assets, increasing production output at lower costs of all resources are used more often. The intensification of modern production is pushed by competition, which forces producers to reduce their costs and increase their productivity for more and normal profits. Intensification of modern production leads not only to saving labor, but to save on all resources: labor, material, energy, natural, financial, and others. The prospect of any production lies in the introduction of something new, new product, new technology, new equipment, a new organization of work, and so on. Otherwise, in conditions of competition and a fairly high level of development of productive forces, it is impossible to achieve good success. It is impossible to increase productivity without updating obsolete equipment, changing technology, applying a more perfect organization of work and new materials. The information explosion and the current pace of growth of scientific information, which one needs to have time to pass on to students during the study, prompts teachers to seek a way out of the situation at the expense of new pedagogical techniques. Intensification of modern production motivates to change approaches in the training process of professional education professionals. The modern educator of professional education faces the task of actively searching for the newest, more intensive methods, forms and means of teaching in order to develop cognitive activity among students. Therefore, the creation of problem situations in the training of teachers of vocational training is a key to increasing the effectiveness of training in an intensification of modern production [6]

Застосування методу екологічної оцінки будівельних матеріалів при порівнянні різних аспектів впливу на навколишнє середовище

This article discusses the methods of environmental assessment of building materials in terms of their hygienic safety, identifies these safety criteria and characteristics to assess the impact of building materials on human health. On their basis, we developed ecological ways to improve the sanitary and hygienic properties of finishing materials.У даній статті розглянуті методи екологічної оцінки будівельних матеріалів за показниками їх гігієнічної безпеки, визначені ці критерії безпеки і характеристики для оцінки впливу будівельних матеріалів на здоров’я людини. На їх основі розробили екологічні шляхи покращення санітарно-гігієнічних властивостей оздоблювальних матеріалів

Genetic and Biochemical Characterization of Human AP Endonuclease 1 Mutants Deficient in Nucleotide Incision Repair Activity

Background: Human apurinic/apyrimidinic endonuclease 1 (APE1) is a key DNA repair enzyme involved in both base excision repair (BER) and nucleotide incision repair (NIR) pathways. In the BER pathway, APE1 cleaves DNA at AP sites and 39-blocking moieties generated by DNA glycosylases. In the NIR pathway, APE1 incises DNA 59 to a number of oxidatively damaged bases. At present, physiological relevance of the NIR pathway is fairly well established in E. coli, but has yet to be elucidated in human cells. Methodology/Principal Finding: We identified amino acid residues in the APE1 protein that affect its function in either the BER or NIR pathway. Biochemical characterization of APE1 carrying single K98A, R185A, D308A and double K98A/R185A amino acid substitutions revealed that all mutants exhibited greatly reduced NIR and 39R59 exonuclease activities, but were capable of performing BER functions to some extent. Expression of the APE1 mutants deficient in the NIR and exonuclease activities reduced the sensitivity of AP endonuclease-deficient E. coli xth nfo strain to an alkylating agent, methylmethanesulfonate, suggesting that our APE1 mutants are able to repair AP sites. Finally, the human NIR pathway was fully reconstituted in vitro using the purified APE1, human flap endonuclease 1, DNA polymerase b and DNA ligase I proteins, thus establishing the minimal set of proteins required for a functional NIR pathway in human cells. Conclusion/Significance: Taken together, these data further substantiate the role of NIR as a distinct and separable functio

Lys98 Substitution in Human AP Endonuclease 1 Affects the Kinetic Mechanism of Enzyme Action in Base Excision and Nucleotide Incision Repair Pathways

Human apurinic/apyrimidinic endonuclease 1 (APE1) is a key enzyme in the base excision repair (BER) and nucleotide incision repair (NIR) pathways. We recently analyzed the conformational dynamics and kinetic mechanism of wild-type (wt) protein, in a stopped-flow fluorescence study. In this study, we investigated the mutant enzyme APE1K98A using the same approach. Lys98 was known to hydrogen bond to the carboxyl group of Asp70, a residue implicated in binding the divalent metal ion. Our data suggested that the conformational selection and induced fit occur during the enzyme action. We expanded upon the evidence that APE1 can pre-exist in two conformations. The isomerization of an enzyme-product complex in the BER process and the additional isomerization stage of enzyme-substrate complex in the NIR process were established for APE1K98A. These stages had not been registered for the wtAPE1. We found that the K98A substitution resulted in a 12-fold reduction of catalytic constant of 5′-phosphodiester bond hydrolysis in (3-hydroxytetrahydrofuran-2-yl)methyl phosphate (F, tetrahydrofuran) containing substrate, and in 200-fold reduction in 5,6-dihydrouridine (DHU) containing substrate. Thus, the K98A substitution influenced NIR more than BER. We demonstrated that the K98A mutation influenced the formation of primary unspecific enzyme-substrate complex in a complicated manner, depending on the Mg2+ concentration and pH. This mutation obstructed the induced fit of enzyme in the complex with undamaged DNA and F-containing DNA and appreciably decreased the stability of primary complex upon interaction of enzyme with DNA, containing the natural apurinic/apyrimidinic (AP) site. Furthermore, it significantly delayed the activation of the less active form of enzyme during NIR and slowed down the conformational conversion of the complex of enzyme with the cleavage product of DHU-substrate. Our data revealed that APE1 uses the same active site to catalyze the cleavage of DHU- and AP-substrates

Determination of the propellant combustion law under ballistic experiment conditions

The main characteristics of ballistic experiment are the maximum pressure in the combustion chamber P max and the projectile velocity at the time of barrel leaving U M. During the work the burning law of the new high-energy fuel was determined in a ballistic experiment. This burning law was used for a parametric study of depending P max and U M from a powder charge mass and a traveling charge at initial temperature of + 20 °C was carried out. The optimal conditions for loading were obtained for improving the muzzle velocity by 14.9 %. Under optimal loading, there is defined the conditions, which is possible to get the greatest value muzzle velocity projectile at pressures up to 600 MPa

Mathematical model and software for investigation of internal ballistic processes in high-speed projectile installations

This paper describes a software package that allows to explore the interior ballistics processes occurring in a shot scheme with bulk charges using propellant pasty substances at various loading schemes, etc. As a mathematical model, a model of a polydisperse mixture of non-deformable particles and a carrier gas phase is used in the quasi-one-dimensional approximation. Writing the equations of the mathematical model allows to use it to describe a broad class of interior ballistics processes. Features of the using approach are illustrated by calculating the ignition period for the charge of tubular propellant

Photoelectric and Spectral Properties of Composite Films based on GCBE-Oligomer with Different Concentrations of Polymethine Dyes

Thin film of composites based on N-epoxypropylcarbazole and n-butylglycidyl ether co-oligomer (GCBE) sensitized by various concentrations of cationic polymethine dyes with different polymethine chain length have been prepared. Their photophysical, electrical, and spectral properties have been investigated. All studied composite films have been shown to exhibited photoconductivity effect. In film composites with high concentration of the dye photovoltaic effect have been detected. The diffusion nature of this effect and its features correlation with electronic properties of PCFs components has been established

Apparent counter-rotation in the torus of NGC 1068: influence of an asymmetric wind

The recent ALMA maps together with observations of H$_2$O maser emission seem to suggest the presence of a counter-rotation in the obscuring torus of NGC 1068. We propose to explain this phenomenon as due to the influence of a wind, considered as radiation pressure, and the effects of torus orientation. In order to test this idea: 1. we make $N$-body simulation of a clumpy torus taking into account mutual forces between particles (clouds); 2. we apply ray-tracing algorithm with the beams from the central engine to choose the clouds in the torus throat that can be under direct influence of the accretion disk emission; 3. we use semi-analytical model to simulate the influence of the asymmetrical radiation pressure (wind) forced on the clouds in the torus throat. An axis of such a wind is tilted with respect to the torus symmetry axis; 4. we orient the torus relative to an observer and again apply ray-tracing algorithm. In this step the beams go from an observer to the optically thick clouds that allows us to take into account the mutual obscuration of clouds; 5. after projecting on the picture plane, we impose a grid on the resulting cloud distribution and find the mean velocity of clouds in each cells to mimic the ALMA observational maps. By choosing the parameters corresponding to NGC 1068 we obtain the model velocity maps that emulate the effect of an apparent counter-rotation and can explain the discovery made by ALMA.Comment: 11 pages, 11 figures, Accepted for publication in MNRA