The potentiodynamic bottom-up growth of the tin oxide nanostructured layer for gas-analytical multisensor array chips

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

Isotope analysis of highly enriched “Silicon-28” by high-resolution inductively coupled plasma mass spectrometry using an internal standard

Для изучения изотопических эффектов в полупроводниковых материалах требуются монокристаллы с высокой химической и изотопной чистотой. Надежность полученных данных о величине и направлении изотопических сдвигов зависит от точности определения концентрации всех стабильных изотопов. При изотопном анализе обогащенного “кремния-28” с высокой степенью обогащения (более 99.99 %) необходимо определять примеси изотопов 29Si и 30Si на уровне 10-3 ¸ 10-5 ат. %. На таком уровне концентраций указанные изотопы можно рассматривать как примеси. Достижение высокой точности измерений при одновременной регистрации основного и “примесных” изотопов в таком широком интервале концентраций затруднительно. Регистрацию аналитических сигналов изотопов кремния приходится проводить на растворах с разной концентрацией матрицы. Использование растворов с высокой концентрацией матричного элемента требует введения поправок на матричные помехи и дрейф чувствительности прибора в процессе измерения. Снизить влияние необратимых неспектральных помех и дрейфа чувствительности можно при использовании метода внутренней стандартизации. Противоречивость литературных данных о критериях выбора внутреннего стандарта потребовала исследования поведения сигналов элементов “кандидатов во внутренний стандарт“ для одноколлекторного масс-спектрометра высокого разрешения с индуктивно связанной плазмой ELEMENT 2 от концентрации матричного элемента и природы растворителя, а также от времени распыления раствора. Учет необратимых неспектральных матричных помех и аппаратного дрейфа при изотопном анализе обогащенного “кремния-28” и исходного 28SiF4 методом масс-спектрометрии с индуктивно связанной плазмой позволил снизить в 3-5 раз случайную составляющую и более чем на порядок систематическую составляющую погрешности измерения по сравнению с методом внешнего стандарта. Это позволило проводить с достаточной точностью оперативный контроль изотопного состава обогащенного “кремния-28”, как в виде тетрафторида кремния, так и получаемого из него поликристаллического кремния с помощью одного серийного прибора в интервале изотопных концентраций 0.0001–99.999 ат. %.In order to study the isotopic effects in semiconductor materials, single crystals of high chemical and isotopic purity are required. The reliability of the obtained data on the magnitude and the direction of isotopic shifts depends on the accuracy of determining the concentration of all stable isotopes. In the isotopic analysis of enriched “silicon-28” with a high degree of enrichment (> 99.99%), it is necessary to determine the impurities of 29Si and 30Si isotopes at the level of 10-3 ¸ 10-5 at. %. At this concentration level, these isotopes can be considered as impurities. It is difficult to achieve high measurement accuracy with simultaneous registration of the main and “impurity” isotopes in such a wide range of concentrations. The registration of analytical signals of silicon isotopes must be carried out in the solutions with different matrix concentrations. The use of the solutions with the high concentration of the matrix element requires the introduction of corrections for matrix noise and the drift of the instrument sensitivity during the measurement. It is possible to reduce the influence of the irreversible non-spectral interference and sensitivity drift by using the method of internal standardization. The inconsistency of the literature data on the selection criteria for the internal standard required studying the behavior of the signals of the “candidates for the internal standard” for the ELEMENT 2 single-collector high-resolution inductively coupled plasma mass spectrometer on the matrix element concentration and the nature of the solvent, as well as on the solution nebulizing time. Accounting for the irreversible non-spectral matrix noise and instrumental drift in isotopic analysis of enriched “silicon-28” and initial 28SiF4 by inductively coupled plasma mass spectrometry had allowed us to reduce by 3-5 times the random component and by more than an order of magnitude the systematic component of the measurement error in comparison with the external standard method. This made it possible to carry out, with sufficient accuracy, the operational control of the isotopic composition of enriched “silicon-28”, both in the form of silicon tetrafluoride and polycrystalline silicon obtained from it, using a single serial device in the range of isotopic concentrations 0.0001–99.999%.Работа выполнена в соответствии с Программой фундаментальных научных исследований государственных академий наук на 2019-2021 годы № темы 0095-2019-0001.The work was accomplished according to the Program of Fundamental Scientific Research of Governmental Academies of Sciences for 2019-2021, topic No. 0095-2019-0001

SMARTPHONE-BASED APPROACH TO ADVANCED DRIVER ASSISTANCE SYSTEM (ADAS) RESEARCH AND DEVELOPMENT

Subject of Research.The paper deals with findings and presents asmartphone-based approach to advanced driver assistance system (ADAS) research and development.The approach is based on the data of smartphone cameras and sensors. The line of researchis associated with the developmentof mobile advanced driver assistance system (ADAS). Method.The proposedapproach isbased on the use of driver'sand vehicle behavior ontologies. Current ADAS systems can be divided into two main categories according to the method of implementation: mobile applications, manually installed by the driver from the application stores, and safetyhardware and softwaresystems,integrated into vehicles by manufacturesor in the automotive service centers.Mobile application installed on the smartphone uses the built-in rear and front-facing cameras and sensors to monitor both the road and vehicles ahead, and at the same time the driver in order to prevent traffic collisions. The service consists of components for objects recognition in the images obtained with cameras, and components for traffic situation analysis. Main Results. The driver safety mobile application has been developedfor the use on mobile phones.The mobile phone is mounted on the windshield of a car.In case of dangerous event occurrence, the application engine will make an audible or vibration signal to inform the driver to be concentratedand more vigilant. For example, road obstacles, rear-end and stationary vehicle accidents are the most common accident types.The mobile application detects whether a crash is imminent by computing the ‘Time To Contact’ (TTC) taking into account host vehicle speed, relative speed and relative acceleration.If the driver doesn’t maintain safe minimum distance with the car immediately ahead, the mobile application will alert the driver by displaying an attention icon with an audible alert. The dual-camera sensing application is designed to help the drivers increase the trip safety and assess and improve theirdriving skills. Practical Relevance.The proposed approach is designed to help the driver in the driving process, anticipate hazards and provide the driver with appropriate messages through his/her mobile phone

Expression, purification, crystallization and preliminary X-ray structure analysis of Vibrio cholerae uridine phosphorylase in complex with thymidine

A high-resolution structure of the complex of Vibrio cholerae uridine phosphorylase (VchUPh) with its physiological ligand thymidine is important in order to determine the mechanism of the substrate specificity of the enzyme and for the rational design of pharmacological modulators. Here, the expression and purification of VchUPh and the crystallization of its complex with thymidine are reported. Conditions for crystallization were determined with an automated Cartesian Dispensing System using The Classics, MbClass and MbClass II Suites crystallization kits. Crystals of the VchUPh–thymidine complex (of dimensions ∼200–350 µm) were grown by the sitting-drop vapour-diffusion method in ∼7 d at 291 K. The crystallization solution consisted of 1.5 µl VchUPh (15 mg ml(−1)), 1 µl 0.1 M thymidine and 1.5 µl reservoir solution [15%(w/v) PEG 4000, 0.2 M MgCl(2).6H(2)O in 0.1 M Tris–HCl pH 8.5]. The crystals diffracted to 2.12 Å resolution and belonged to space group P2(1) (No. 4), with unit-cell parameters a = 91.80, b = 95.91, c = 91.89 Å, β = 119.96°. The Matthews coefficient was calculated as 2.18 Å(3) Da(−1); the corresponding solvent content was 43.74%

Air-Oxidation of Nb Nano-Films

X-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