Automated mesh production for limiter Wendelstein-7X configuration

A tool for automated mesh production for 3D multifluid plasma transport code Findif is presented. Mesh points for the code lie on magnetic field lines, which, in general, form a complicated tangle. Open field lines that end on solid parts of the machine are the source of difficulties. These lines are usually short and thousands of them are needed. A tool that helps to pick lines for the mesh that is described in this paper is based on calculation the distances of lines already admitted to the mesh and candidate ones. The results of the code run for the limiter configuration (OP-1.1 experimental phase) of the Wendelstein-7X device are shown here. Reasonably even coverage of space by points is achieved.Представлен трёхмерный код Findif для переноса многожидкостной модели плазмы как инструмент автоматизированного производства сетки. Сетка точек для кода лежит на магнитных силовых линиях, которые, вообще говоря, образуют сложную конфигурацию. Открытые силовые линии, которые ограничены твёрдыми частями механизма, являются источником сложностей. Эти линии, как правило, короткие, и нужны тысячи из них. Инструмент, который помогает подобрать линии для сетки, описан в этой статье и основан на вычислении расстояния линий уже допущенных к сетке и кандидатов из них. Представлены результаты прогона кода для конфигурации лимитера (OP-1.1 экспериментальная фаза) стелларатора Wendelstein-7X.Представлено тривимірний код Findif для перенесення багаторідинної моделі плазми як інструмент автоматизованого виробництва сітки. Сітка точок для коду лежить на магнітних силових лініях, які, взагалі кажучи, утворюють складну конфігурацію. Відкриті силові лінії, що обмежені твердими частинами механізма, є джерелом труднощів. Ці лінії, як правило, короткі, і потрібні тисячі з них. Інструмент, який допомагає підібрати лінії для сітки, описаний в цій статті і заснований на обчисленні відстані ліній вже допущених до сітки і кандидатів з них. Представлено результати прогону коду для конфігурації лимитера (OP-1.1 експериментальна фаза) стеларатора Wendelstein-7X

Direction-sensitive graphene flow sensor

Graphene flow sensors hold great prospects for applications, but also encounter many difficulties, such as unwanted electrochemical phenomena, low measurable signal and limited dependence on the flow direction. This study proposes a novel approach allowing for the detection of a flow direction-dependent electric signal in aqueous solutions of salts, acids and bases. The key element in the proposed solution is the use of a reference electrode which allows external gating of the graphene structure. Using external gating enables to enhance substantially the amplitude of the flow-generated signal. Simultaneous measurement of the reference electrode current allows us to recover a flow-direction-sensitive component of the flow-induced voltage in graphene. The obtained results are discussed in terms of the Coulomb interaction and other phenomena which can be present at the interface of graphene with the aqueous solution.Comment: 7 pages, 6 figure

Findif code simulations of OP-1.1 Wendelstein 7-X discharges

The current development state of the finite difference, multi-fluid, 3D plasma code Findif is detailed. The code was run on four meshes prepared for the OP-1.1 wall geometry of the Wendelstein 7-X stellarator. The meshes were produced for 4 magnetic configurations; two of them are finite-beta (non vacuum). The simulated volume covers plasma edge; the computations of limiter heat load distributions were the main goal. Plasma radiation was not taken into account.Докладно наведено поточну стадію розробки кінцево-різницевого тривимірного коду Findif для багаторідинної моделі плазми. Код було запущено на чотирьох сітках, підготовлених для геометрії стінки OP-1.1 стеларатора Wendelstein 7-X. Сітки згенеровано для 4-х магнітних конфігурацій, дві з яких – зі скінченним бета (не вакуум). Змодельований об’єм охоплює край плазми; основна мета полягає в розрахунках розподілів теплових навантажень на лімітер. Випромінювання плазми не враховувалося.Подробно изложена текущая стадия разработки конечно-разностного трехмерного кода Findif для многожидкостной модели плазмы. Код был запущен на четырех сетках, подготовленных для геометрии стенки OP-1.1 стелларатора Wendelstein 7-X. Сетки сгенерированы для 4-х магнитных конфигураций, две из которых – с конечным бета (не вакуум). Смоделированный объем охватывает край плазмы; основная цель заключается в расчетах распределений тепловых нагрузок на лимитер. Излучение плазмы не учитывалось

Excitonic luminescence of the I2_2-intercalated HfS2_2

Photoluminescence from bulk HfS$_2$ grown by the chemical vapor transport (CVT) method is reported. A series of emission lines is apparent at low temperature in the energy range of 1.4 - 1.5 eV. Two groups of the observed excitonic transitions followed by their replicas involving acoustic and optical phonons are distinguished using classical intensity correlation analysis. The emission is attributed to the recombination of excitons bound to iodine (I$_2$) molecules intercalated between layers of HfS$_2$. The I$_2$ molecules are introduced to the crystal during the growth as halogen transport agents in the CVT growth process. Their presence in the crystal is confirmed by secondary ion mass spectroscopy.Comment: 5 pages, 6 figure

Consequence of one-electron oxidation and one-electron reduction for aniline

Quantum-chemical calculations were performed for all possible isomers of neutral aniline and its redox forms, and intramolecular proton-transfer (prototropy) accompanied by π-electron delocalization was analyzed. One-electron oxidation (PhNH2 – e → [PhNH2]+•) has no important effect on tautomeric preferences. The enamine tautomer is preferred for oxidized aniline similarly as for the neutral molecule. Dramatical changes take place when proceeding from neutral to reduced aniline. One-electron reduction (PhNH2 + e → [PhNH2]-•) favors the imine tautomer. Independently on the state of oxidation, π- and n-electrons are more delocalized for the enamine than imine tautomers. The change of the tautomeric preferences for reduced aniline may partially explain the origin of the CH tautomers for reduced nucleobases (cytosine, adenine, and guanine)

The effect of climate change on avian offspring production: A global meta-analysis

Climate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average offspring production has declined in recent decades, but considerable differences were found among species and populations. A total of 56.7% of populations showed a declining trend in offspring production (significant in 17.4%), whereas 43.3% exhibited an increase (significant in 10.4%). The results show that climatic changes affect offspring production through compounded effects on ecological and life history traits of species. Migratory and larger-bodied species experienced reduced offspring production with increasing temperatures during the chick-rearing period, whereas smaller-bodied, sedentary species tended to produce more offspring. Likewise, multi-brooded species showed increased breeding success with increasing temperatures, whereas rising temperatures were unrelated to repro- ductive success in single-brooded species. Our study suggests that rapid declines in size of bird populations reported by many studies from different parts of the world are driven only to a small degree by changes in the production of young