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Uridine phosphorylase catalyzes the phosphorolysis of ribonucleosides, with the nitrogenous base and ribose 1-phosphate as products. Additionally, it catalyzes the reverse reaction of the synthesis of ribonucleosides from ribose 1-phosphate and a nitrogenous base. However, the enzyme does not catalyze the synthesis of nucleosides when the substrate is a nitrogenous base substituted at the 6-­position, such as 6-methyluracil (6-MU). In order to explain this fact, it is essential to investigate the three-dimensional structure of the complex of 6-MU with uridine phosphorylase. 6-MU is a pharmaceutical agent that improves tissue nutrition and enhances cell regeneration by normalization of nucleotide exchange in humans. 6-MU is used for the treatment of diseases of the gastrointestinal tract, including infectious diseases. Here, procedures to obtain the uridine phosphorylase from the pathogenic bacterium Vibrio cholerae (VchUPh), purification of this enzyme, crystallization of the complex of VchUPh with 6-MU, and X-ray data collection and preliminary X-ray analysis of the VchUPh–6-MU complex at atomic resolution are reported.

Pseudotuberculosis is an acute infectious disease characterized by a lesion of the gastrointestinal tract. A positive therapeutic effect can be achieved by selectively suppressing the activity of uridine phosphorylase from the causative agent of the disease Yersinia pseudotuberculosis. The synergistic effect of a combination of the chemotherapeutic agent 5-fluorouracil and antimicrobial drugs, which block the synthesis of pyrimidine bases, on the cells of pathogenic protozoa and bacteria is described in the literature. The three-dimensional structures of uridine phosphorylase from Yersinia pseudotuberculosis (YptUPh) both in the ligand-free state and in complexes with pharmacological agents are unknown, which hinders the search for and design of selective inhibitors of YptUPh. The three-dimensional structure of the ligand-free homodimer of YptUPh was determined by homology-based molecular modeling. The three-dimensional structure of the subunit of the YptUPh molecule belongs to α/β proteins, and its topology is a three-layer α/β/α sandwich. The subunit monomer of the YptUPh molecule consists of 38% helices and 24% β strands. A model of the homodimer structure of YptUPh in a complex with 5-FU was obtained by the molecular docking. The position of 5-FU in the active site of the molecule is very consistent with the known data on the X-ray diffraction structures of other bacterial uridine phosphorylases (the complex of uridine phosphorylase from Salmonella typhimurium (StUPh) with 5-FU, ID PDB: 4E1V and the complex of uridine phosphorylase from Escherichia coli (EcUPh) with 5-FU and ribose 1-phosphate, ID PDB: 1RXC).

We report a deposition of the tin oxide/hydroxide nanostructured layer by the potentiodynamic method from acidic nitrate solutions directly over the substrate, equipped with multiple strip electrodes which is employed as a gas-analytical multisensor array chip. The electrochemical synthesis is set to favor the growth of the tin oxide/hydroxide phase, while the appearance of metallic Sn is suppressed by cycling. The as-synthesized tin oxide/hydroxide layer is characterized by mesoporous morphology with grains, 250-300 nm diameter, which are further crystallized into fine SnO₂ poly-nanocrystals following heating to 300 °C for 24 h just on the chip. The fabricated layer exhibits chemiresistive properties under exposure to organic vapors, which allows the generation of a multisensor vector signal capable of selectively distinguishing various vapors.

The article theoretically substantiates a possibility of self-excitation of oscillations of wheeled tractors frame in the longitudinal plane when working in traction mode. There was used the dependence of rolling pneumatic wheel radius from the vertical load and torque, mathematical model of a rolling pneumatic wheel with variable vertical load and dual-mass linear model of oscillations of the tractor frame in the longitudinal plane.

In this paper, we demonstrate the concept of the situation analysis of dangerous driving events for smartphones to fully understand the driving situation in a given scenario in a real time and to undertake actions necessary to avoid road accidents. To fulfil these, we utilize a wide array of sensors for creating a consistent and extendable description of most common dangerous situations, a situation model and situation analysis. In the situation model, on-board smartphone sensing signals are used to build up a representation of the environment around and within the vehicle. On top of the situation model, a situation analysis is established to detect driver hazards, according to the given description of the driving situation, and provide a driving strategy to prevent such dangerous situations. The paper describes the details of the algorithms, following by simulation results, which show the feasibility of the proposed algorithm.

The activation of xenobiotics often causes malignant tumor cells to resist chemotherapeutic treatment. Uridine phosphorylase is the key enzyme of pyrimidine metabolism and catalyzes the reversible phosphorylation of uridine with the formation of uracil and ribose-1-phosphate. High-selectivity anticancer agents based on uridine phosphorylase inhibitors are promising for treating both oncological and infection diseases. New medicinal preparations can be predicted and rationally developed only on the basis of detailed biomedical, structural, and functional knowledge about the biomacromolecular target enzyme-drug complex.

The three-dimensional structures of three complexes of Salmonella typhimurium uridine phosphorylase with the inhibitor 2,2′-anhydrouridine, the substrate PO4, and with both the inhibitor 2,2′-anhydrouridine and the substrate PO4 (a binary complex) were studied in detail by X-ray diffraction. The structures of the complexes were refined at 2.38, 1.5, and 1.75 A resolution, respectively. Changes in the three-dimensional structure of the subunits in different crystal structures are considered depending on the presence or absence of the inhibitor molecule and (or) the phosphate ion in the active site of the enzyme. The presence of the phosphate ion in the phosphate-binding site was found to substantially change the orientations of the side chains of the amino-acid residues Arg30, Arg91, and Arg48 coordinated to this ion. A comparison showed that the highly flexible loop L9 is unstable. The atomic coordinates of the refined structures of the complexes and the corresponding structure factors were deposited in the Protein Data Bank (their PDB ID codes are 3DD0 and 3C74). The experimental data on the spatial reorganization of the active site caused by changes in its functional state from the unligated to the completely inhibited state suggest the structural basis for the mechanism of inhibition of Salmonella typhimurium uridine phosphorylase.

The spatial organization of the homodimer of unligated uridine phosphorylase from Salmonella typhimurium (St UPh) was determined with high accuracy. The structure was refined at 1.80 A resolution to R work = 16.1% and R free = 20.0%. The rms deviations for the bond lengths, bond angles, and chiral angles are 0.006 A, 1.042°, and 0.071°, respectively. The coordinate error estimated by the Luzzati plot is 0.166 A. The coordinate error based on the maximum likelihood is 0.199 A. A comparative analysis of the spatial organization of the homodimer in two independently refined structures and the structure of the homodimer St UPh in the complex with a K+ ion was performed. The substrate-binding sites in the homodimers StUPhs in the unligated state were found to act asynchronously. In the presence of a potassium ion, the three-dimensional structures of the subunits in the homodimer are virtually identical, which is apparently of importance for the synchronous action of both substrate-binding sites. The atomic coordinates of the refined structure of the homodimer and structure factors have been deposited in the Protein Data Bank (PDB ID code 3DPS).

Purpose. In this paper it is necessary to analyze the types of competition in the transport market in order to find ways to improve the competitiveness of railway transport and to determine the ensuring equal conditions for all market participants by eliminating discrimination in competition. Methodology. Analysis of recent research and publications on the subject was held by the authors. The question of the development of competition, increased competitiveness in railway transport was investigated. Attention is drawn to the fact that due to the decline in traffic volumes on all modes of transport competition may significantly change the usual sphere the effective use of different modes of transport. Every mode of transport occupies a particular segment of the transport market, taking into account its technical and economic features, weakly competing, and in some cases do not compete with each other (except the road transport). However, it is entirely possible competition inside these segments.Findings. The problems of management of competitiveness, including the transport market, which required extensive analysis and serious scientific study, were identified. Originality. As a result of this work the features of transport and production of transport in modern conditions were structured. The dependences of passenger turnover and freight turnover by mode of transport over the past decade were shown. The question of additional profits by providing the cargo owners a range of service was examined. The optimal combination of cost and quality of such services at each transportation company promotes increasing its competitive status. Practical value. Competition between enterprises of the industry put the aim of improving the competitiveness of not only railway subsystems directly involved in technology movement of cargoes and the movement of passengers, but also the organization of infrastructure in the first place – subsystems to expand services and improve service for passengers and cargo owners. Ensuring of equal conditions for all market participants is achieved through a ban of three key anti-competitive actions: the adoption of agreements restricting competition; abuse of a dominant (monopolistic) position and mergers, which result in a dominant market position to restrict competition., Цель. В работе необходимо провести анализ видов конкуренции на транспортном рынке с целью поиска путей повышения конкурентоспособности железнодорожного транспорта и определить вопросы обеспечения равных условий для всех участников рынка путем устранения дискриминации в конкуренции. Методика. Авторами проведен анализ последних исследований и публикаций по данной проблематике. Исследованы вопросы развития конкуренции, повышения уровня конкурентоспособности на железнодорожном транспорте. Обращается внимание на то, что в связи со спадом объемов перевозок на всех видах транспорта конкуренция может существенно изменить сложившиеся ранее привычные сферы эффективного применения различных видов транспорта. Каждый вид транспорта занимает определенный сегмент транспортного рынка с учетом своих технико-экономических особенностей, слабо конкурируя, а в ряде случаев – и вовсе не конкурируя друг с другом (кроме автомобильного транспорта). Однако внутри этих сегментов вполне возможна конкуренция. Результаты. В процессе исследования выявлены проблемы управления конкурентоспособностью, в том числе на транспортном рынке, которые требовали всестороннего анализа и серьезного научного обоснования. Научная новизна. В результате работы были структурированы особенности транспорта и транспортной продукции в современных условиях. Приведены зависимости пассажиро- и грузооборота по видам транспорта за последние десять лет. Рассмотрен вопрос получения дополнительной прибыли путем предоставления грузовладельцу ряда сервисных оплачиваемых услуг. Оптимальное сочетание стоимости и качества данных услуг для каждого транспортного предприятия способствует повышению его конкурентного статуса. Практическая значимость. Конкуренция между предприятиями отрасли поставила вопрос о повышении конкурентоспособности не только железнодорожных подсистем, непосредственно задействованных в технологиях движения грузов и передвижения пассажиров, но и организации инфраструктуры. Это касается, в первую очередь, – подсистем по расширению услуг и улучшению сервиса для пассажиров и грузовладельцев. Обеспечение равных условий для всех участников рынка достигается благодаря запрету трех ключевых антиконкурентных действий: принятия соглашений, ограничивающих конкуренцию; злоупотребление доминирующим (монопольным) положением и слияния, которые приводят к доминирующей позиции на рынке и ограничивают конкуренцию., Мета. У роботі необхідно провести аналіз видів конкуренції на транспортному ринку з метою пошуку шляхів підвищення конкурентоспроможності залізничного транспорту та визначити питання щодо забезпечення рівних умов для всіх учасників ринку шляхом усунення дискримінації у конкуренції. Методика. Авторами зроблений аналіз останніх досліджень і публікацій за даною проблематикою. Досліджено питання розвитку конкуренції, підвищення рівня конкурентоспроможності на залізничному транспорті. Звертається увага на те, що, у зв’язку зі спадом обсягів перевезень на всіх видах транспорту, конкуренція може істотно змінити сформовані раніше звичні сфери ефективного застосування різних видів транспорту. Кожен вид транспорту займає певний сегмент транспортного ринку з урахуванням своїх техніко-економічних особливостей, слабо конкуруючи, а в ряді випадків – і зовсім не конкуруючи, один із одним (крім автомобільного транспорту). Однак всередині цих сегментів цілком можлива конкуренція. Результати. Авторами виявлено проблеми управління конкурентоспроможністю, в тому числі на транспортному ринку, які вимагали всебічного аналізу та серйозного наукового обґрунтування. Наукова новизна. У результаті роботи були структуровані особливості транспорту та транспортної продукції в сучасних умовах. Наведені залежності пасажиро- та вантажообігів за видами транспорту за останні десять років. Розглянуто питання отримання додаткового прибутку шляхом надання вантажовласникові ряду сервісних оплачуваних послуг. Оптимальне поєднання вартості та якості даних послуг для кожного транспортного підприємства сприяє підвищенню його конкурентного статусу. Практична значимість. Конкуренція між підприємствами галузі поставила питання про підвищення конкурентоспроможності не тільки залізничних підсистем, безпосередньо задіяних у технологіях руху вантажів та пересування пасажирів, але й організації інфраструктури. Це стосується, в першу чергу, підсистем із розширення послуг та поліпшення сервісу для пасажирів і вантажовласників. Досягається забезпечення рівних умов для всіх учасників ринку завдяки забороні трьох ключових антиконкурентних дій: прийняття угод, що обмежують конкуренцію; зловживання домінуючим (монопольним) становищем та злиття, що призводять до домінуючої позиції на ринку та обмежують конкуренцію.

We have studied the influence of organic vapors, acetone and ethanol, on the resistance of potassium titanate nanowire nonwoven net (PTN) at room temperature. We find that the PTN resistance is reproducibly reduced under appearance of the vapor molecules that might be explained by the influence of the adsorbed species on the electronic/ionic transport. The selectivity of the sensor could be greatly enhanced in order to recognize the kind of the vapors by processing a response of the PTN segment array formed at the same substrate by multiple co-planar electrodes.

We report a direct synthesis of tin oxide layers onto Si/SiO2 chip equipped with Pt multiple electrodes to develop new gas-analytical multisensor arrays. The tailored local morphology of the layer makes it possible to differentiate the gas response of each layer segment and to build a gas-selective vector signal recognized by pattern recognition algorithms in frames of conventional multisensor principles. The response of the chip to alcohols is in the ppm range.

The implementation and experimental approbation of gas-analytical multisensor chip based on thermocatalytic effect has been considered. The chip is equipped with a polycrystalline Al 2 O 3 layer functionalized by PdCl 2 and H 2 PtCl 6 solutions and segmented by coplanar electrodes which divide it into four thermocatalytic sensor elements. The developed chip is found to be sensitive to vapors of acetone and isopropanol in a mixture with air (concentration: 350000 ppm for acetone, 70000 ppm for isopropanol). A vector signal of the array consisted of these four catalytic combustion-type sensor elements located at the chip shows a possibility to selectively recognize the test gas mixtures by processing via a linear-discriminant analysis.

There was an error made in the name of the author in the above published article. The fourth author's name should have appeared as ‘D. P. Potapenko’. This error has now been rectified in the original article.

The heat and mass transfer in the process of drying of high-humidity materials by their depressurization has been investigated. The results of experimental investigation and mathematical simulation of the indicated process are presented. They allow one to determine the regularities of this process and predict the quality of the finished product. A technological scheme and an engineering procedure for calculating the drying of the liquid base of a soap are presented.

This study attempts to reveal the influence of major defects such as micropipes and planars on the polishing characteristics of silicon carbide (SiC) wafers. SiC wafers were lapped and finish-polished using chemical-mechanical polishing. The surface finish examinations were performed using atomic force microscopy along with a stylus instrument and revealed that for SiC wafers with a low defect density the average surface roughness is less than 5 A. It was found that scratches are generated due to chipping of the walls of micropipes and planars. Moreover, depending on the micropipe density (MPD), wavy features or so-called "orange peels" are created. The quantitative dependence of roughness parameters and the uniformity of surface finish on the micropipe density were evaluated and the occurrence of orange peel was found to increase when the MPD exceeds 100 cm-2.

The action of differently oriented magnetic fields on the parameters of bow shock created in the vicinity of aerodynamic bodies placed into the supersonic gas-plasma flows is studied. For these experiments two types of the high speed plasma jet sources are used—magneto-plasma compressor (MPC) and powerful pulse capillary type discharge. MPC allows to create the plasma jets with gas flow velocity of 10 ± 2 km/s, lifetime 30–50 μs, temperature Te ≈ 3 ± 0.5 eV, electron density about ne ∼ 1016cm−3 and temperature Te ≈ 3 ± 0.5 eV. The jet source based on powerful capillary discharge creates the flows with lifetime 1–20 ms, Mach numbers 3–8, plasma flow velocity 3–10 km/s, vibration and rotation temperatures 9000–14000 and 3800–6000 K respectively. The results of our first experiments show the possibility of using gas-plasma sources based on MPC and powerful capillary discharge for aerodynamic and radiophysical experiments. Comparatively small magnetic field B = 0.23–0.5 T, applied to the obtained bow shocks, essentially modify them. This can lead to a change in shape and an increase in the distance between the detached shock wave and the streamlined body surface if B is parallel to the jet velocity or to decrease this parameter if B is orthogonal to the oncoming flow. Probably, the first case can be useful for reducing the thermal load and aerodynamic drug of streamlined body and the second case can be used to control the radio-transparency of the plasma layer and solving the blackout problem.

AbstractX-ray photoelectron spectroscopy (XPS) depth chemical and phase profiling of air-oxidized niobium nanofilms has been performed. It is found that oxide layer thicknesses depend on the initial thickness of the niobium nanofilm. The increase in thickness of the initial Nb nano-layer is due to increase in thickness of an oxidized layer.

Many people drive while being tired or drowsy and according to experts, many drivers fail to recognize they are in a fatigued state. The paper describes an ontology-based approach and a real-time prototype of a computer vision system for monitoring driver’s dangerous behaviour patterns such as distraction, drowsiness and reduced vigilance. Our approach focuses on widely used mobile devices, such as a smartphone or a tablet, which have become an integral part of our daily life. The main components of the system consist of a front-facing camera, gyroscope sensor installed on the smartphone and various computer vision algorithms for simultaneous, real-time and non-intrusive monitoring of various visual bio-behaviours that typically characterize a driver’s level of vigilance. The visual behaviours include eyelid movement (PERCLOS percentage of eye closure, eye blink rate), face orientation (face pose), and gaze movement (pupil movement). The two ontological models presented in the paper are a driver model and a vehicle model. Based on these models and the information available from cameras and sensors, the context is created that allows the system to determine dangerous situations using the driver mobile device mounted on the windshield of the vehicle. The system was tested in a simulated environment with subjects of different ethnic backgrounds, genders, ages, with/without glasses, and under different illumination conditions, and it was found very robust, reliable and accurate.

Defect evaluation of silicon carbide (SiC) wafers can be accomplished by potassium hydroxide (KOH) etching. The method described in this work employs etching by KOH in a vapor phase rather than in a liquid phase and this method allows reliable etching of both Si- and C-faces and furthermore it allows the delineation of defects on alternate orientation planes of SiC. Polished SiC wafers were etched in the temperature range from 700 to 1000°C at atmospheric air pressure. Etch pits were observed on (0001), (0001), (1120) and (1100) planes. The shape of the pits was found to be in accordance with the crystallographic symmetry. Activation energies for (0001) and (1120) planes were found to be ~17 kcal/mol and ~20 kcal/mol, respectively. It was demonstrated that the method of KOH vapor etching of SiC is simple for implementation having possibilities to reveal most of the important crystal defects.

On the basis of the differential equations of transfer of energy and mass, a mathematical description of the crystallization of solutions by decreasing continuously the pressure of the medium has been developed. The kinetic dependences obtained from the experiments have been used in simulating the process of crystallization of hexamethylene tetramine. By comparing the experimental and calculated data, the adequacy of the mathematical model to the actual process has been established.

The drag of flat plates with spherical recesses was measured using the direct balance method. The experiments were run in a low-turbulence wind tunnel with a cross-section measuring 1000 × 1000 mm and a length of 400 mm. Three surfaces with recesses 7.0, 3.9, and 1.3 mm in diameter and 0.5, 0.3, and 0.2 mm deep, respectively, were tested. It is shown that on the Reynolds and Mach number ranges Re= (3–9)· 106 and M ≤ 0.3 the spherical recesses add to the drag of a flat plate in turbulent flow. The recesses have almost no effect on the location of laminar-turbulent transition, which occurs at Ret ∼ 3· 106.

A mathematical model for the process of self-freezing of moist materials in a continuously increasing vacuum which is developed on the basis of the approximate solutions obtained by A. V. Luikov for drying of capillary-porous media is presented. Results of experimental investigations into the self-freezing of a moist cloth are given, from which the temperature of supercooling of the surface material layer, the temperature coefficient, and the velocity of deepening of the freezing surface are determined; all of these parameters are used in mathematical simulation of the above process.

The results of a laboratory investigation of the effect of a liquid film covering the inner surface of a circular gas pipe on its hydraulic resistance are given. The problems of the similarity of liquid film flows are considered. It is shown that the liquid film increases the resistance of a hydraulically smooth pipe but can reduce that of a rough pipe due to the decrease in the equivalent roughness.

A mathematical model of heat and mass transfer in wood chips subjected to hydrothermal treatment in a saturated‐steam medium for constant parameters of the external medium is developed. Filling of capillaries with a liquid moving with a finite velocity is responsible for the presence of different zones in which condensate transfer is determined by the corresponding mechanisms.

We present a mathematical model of heat and mass transfer in a chemically reacting medium-multi-component vapor-gas mixture system with decrease in partial pressures of vapor-gas components in a free reactor volume.