Mathematical model of a two-stage process of laser fragmentation of nitrocompound molecules and subsequent laser-induced fluorescence of characteristic fragments

The paper presents a mathematical model describing the kinetics of the two-stage process of laser fragmentation of vapors of nitrocompounds and subsequent nitric oxide (NO-fragments) laser-induced fluorescence. The use of the developed model in the lidar equation for the case of fluorescent objects allows to calculate the expected value of the lidar signal for a particular nitrocompound on the basis of spectroscopic information about the object of detection, parameters of the radiation propagation medium, and transceiver equipment parameter

Enhancement of the Raman lidar sensitivity using overtones of vibrational-rotational Raman bands of oxygen or nitrogen as the reference signals

Influence of the vibrational-rotational Raman bands of molecules of the main components of the atmosphere (oxygen and nitrogen) on the sensitivity of Raman lidar is considered. A method is proposed of using the first overtones of the vibrational-rotational Raman bands of oxygen and nitrogen molecules as the reference signals for the measurement of low concentrations of chemicals in the atmosphere by the Raman method

Remote detection of traces of high energetic materials

The possibility of remote detection of traces of high energetic materials using laser fragmentation/laser-induced fluorescence (LF/LIF) method is studied. Experimental data on the remote visualization of traces of trinitrotoluene, hexogen, composition B, octogen, and tetryl obtained at a distance of 5 m with a scanning lidar detector of traces of high energetic materials are presented

Influence of multiple scattering on parametric X-Ray radiation excited by a beam of relativistic electrons in a single crystal

Parametric X-ray radiation generated by a beam of relativistic electrons in a single-crystal wafer is studied in the Bragg geometry under conditions of multiple electron scattering at target atoms. Expressions are obtained that describe the spectral-angular and angular radiation density under conditions of multiple electron scatterin

Crystal structure of mixed fluorites Ca(1-x)Sr(x)F(2) and Sr(1-x)Ba(x)F(2) and luminescence of Eu(2+) in the crystals

Within the framework of the virtual crystal method implemented in the shell model and pair potential approximation the crystal structure of mixed fluorites Ca(1-x)Sr(x)F(2) and Sr(1-x)Ba(x)F(2) has been calculated. The impurity center Eu(2+) and the distance Eu(2+)-F in this crystals have been also calculated. The low level position of excited 4f65d configuration of the Eu(2+) ion has been expressed using phenomenological dependence on distance E(2+)-F. The dependences of Stokes shift and Huang-Rhys factor on concentration x have been received for yellow luminescence in Sr(1-x)Ba(x)F(2):Eu(2+). The value x, for which the eg -level of Eu(2+) ion will be in conduction band in Sr(1-x)Ba(x)F(2):Eu(2+) has been calculated.Comment: 8 pages, 3 figures. The manuscript is sent to journal 'Physics of the solid state'. The results will be submitted on inernational conference SCINTMAT'2002 in oral session (june,20-22,2002,Ekaterinburg,Russia). Corresponding author e-mail: [email protected]

Methacrylate compositions modified by oligosilsesquioxanes with methacryl and cyclotriphosphazene substituents

Triethoxysilylphosphazenes have been synthesized via hydrosilylation of cyclotriphosphazenes with various contents of 4-allyl-2-methoxyphenoxy groups by triethoxysilane at an equimolar phosphazene - silane ratio. Hydrolytic copolycondensation of the latter compounds with γ-methacryloxypropyltrimethoxy - silane resulted in oligosiloxanes involving functional methacrylic and phosphazene fragment

Rotating strings

Analytical expressions are provided for the configurations of an inextensible, flexible, twistable inertial string rotating rigidly about a fixed axis. Solutions with trivial radial dependence are helices of arbitrary radius and pitch. Non-helical solutions are governed by a cubic equation whose roots delimit permissible values of the squared radial coordinate. Only curves coplanar with the axis of rotation make contact with it.Comment: added to discussion and made small revisions to tex

Механические свойства и электропроводность холоднодеформированного сплава Al–Y–Sc–Er

Aluminum alloys alloyed with rare earth and transition metal are promising materials for electric energy transportation due to their high properties of strength, thermal stability, and electrical conductivity. The features of strengthening, their mechanical properties and electrical conductivity of Al–0.2Y–0.2Sc–0.3Er alloy after cold rolling have been established. The alloy as a cast structure is presented by aluminum solid solution (Al) and dispersed eutectics with τ2 (Al75-76Er11-17Y7-14) phase upon complete dissolution of scandium in (Al), and a content of yttrium and erbium at the level of 0.2–0.3 % each. Cold rolling the ingot accelerates strengthening upon annealing at 270 and 300 °C, reducing the time of achieving peak hardness. The maximum strengthening due to precipitation of L12 dispersoid of Al3(Sc,Y,Er) phase with the average particle size up to 10 nm is achieved after 7 h of annealing at 300 °C after cold rolling. This shows the prevailing heterogeneous mechanism of nucleation due to defects accumulated during cold rolling which stimulates strengthening. The eutectic particles are located mainly along the boundaries, elongated in the rolling direction. Irrespective of the mode of sheet fabrication, the alloy demonstrates high thermal stability up to 400 °C. During annealing of the sheets to 450 °C, their non-recrystallized structure is retained. Ingot annealing at t = 300 °C in 7 h and cold rolling with subsequent annealing under the same conditions provide a high level of mechanical properties and electrical conductivity: σ0.2 = 194 MPa, σu = 210 MPa, δ = 12.1 % and IACS – 60,1 %. The alloy has demonstrated high yield stress up to 100 h of annealing at t = 300 °C.Алюминиевые сплавы, легированные редкоземельными и переходными металлами, являются перспективными материалами для транспортировки электроэнергии ввиду высоких показателей прочности, термической стабильности и электропроводности. В работе определены особенности упрочнения, механические свойства и электропроводность сплава Al–0,2Y–0,2Sc–0,3Er после холодной прокатки. Литая структура сплава представлена алюминиевым твердым раствором (Al) и дисперсной эвтектикой с фазой τ2 (Al75-76Er11-17Y7-14) при полном растворении скандия в (Al) и содержании иттрия и эрбия на уровне 0,2–0,3 % каждого. Холодная прокатка слитка ускоряет упрочнение при отжиге при температурах 270 и 300 °C, уменьшая время достижения пиковой твердости. Максимальное упрочнение за счет выделения L12-дисперсоидов фазы Al3(Sc,Y,Er) со средним размером частиц до 10 нм достигается после 7 ч отжига при температуре 300 °С после холодной прокатки, что говорит о превалировании гетерогенного механизма зарождения за счет дефектов, накопленных в процессе холодной прокатки, стимулирующих упрочнение. Частицы эвтектики располагаются преимущественно вдоль границ, вытягиваясь в направлении прокатки, и вне зависимости от режима получения листа сплав демонстрирует высокую термическую стабильность до 400 °С. В процессе отжига листов до 450 °С сохраняется нерекристаллизованная структура. Отжиг слитка при t = 300 °С в течение 7 ч и холодная прокатка с последующим отжигом в тех же условиях обеспечивают высокий уровень механических свойств и электропроводности: σ0,2 = 194 МПа, σв = 210 МПа, δ = 12,1 % и IACS – 60,1 %. Сплав продемонстрировал высокую стабильность предела текучести вплоть до 100 ч отжига при t = 300 °С

INFLUENCE OF Y ON MICROSTRUCTURE, MECHANICAL AND CORROSION PROPERTIES OF ALLOY Al-4Zn-4Mg-4Cu-Zr

Исследованы влияние Y на микроструктуру, фазовый состав, механические и коррозионные свойства сплава Al-4Zn-4Mg-4Cu-0,2Zr. В литом состоянии микроструктура представляет собой твердый раствор алюминия и дисперсную эвтектику, в которой интерметаллидная фаза обогащена Mg, Cu и Zn. Добавление Y приводит к образованию фаз Al8Cu4Y, (Al,Cu)11Y. Твердость сплава после отжига увеличилась с 86±1 HV до 163 - 172 HV. Добавление иттрия к исходному сплаву Al-4Zn-4Mg-4Cu-0,2Zr позволило повысить коррозионные свойства новых сплавов. Также легирование иттрием обеспечивает меньшее разупрочнение при повышении температуры.The influence of Y on the microstructure, phase composition, mechanical and corrosion properties of the alloy Al-4Zn-4Mg-4Cu-0.2Zr has been investigated. In the cast state, the microstructure is a solid solution of aluminum and dispersed eutectic, in which the intermetallic phase is enriched with Mg Cu and Zn. The addition of Y leads to the formation of Al8Cu4Y, (Al,Cu)11Y phases. The hardness of the alloy after annealing increased from 86±1 HV to 163 - 172 HV. The addition of yttrium to the original alloy Al-4Zn-4Mg-4Cu-0.2Zr allowed to increase the corrosion properties of the new alloys. Also alloying with yttrium provides less destrengthening at increasing temperature.Исследование выполнено за счет гранта Российского научного фонда №22-79-10142, https://rscf.ru/project/22-79-10142

The effect of minor allele frequency on the likelihood of obtaining false positives

Determining the most promising single-nucleotide polymorphisms (SNPs) presents a challenge in genome-wide association studies, when hundreds of thousands of association tests are conducted. The power to detect genetic effects is dependent on minor allele frequency (MAF), and genome-wide association studies SNP arrays include SNPs with a wide distribution of MAFs. Therefore, it is critical to understand MAF's effect on the false positive rate