Spin-to-Orbital Angular Momentum Conversion in Semiconductor Microcavities

We experimentally demonstrate a technique for the generation of optical beams carrying orbital angular momentum using a planar semiconductor microcavity. Despite being isotropic systems, the transverse electric - transverse magnetic (TE-TM) polarization splitting featured by semiconductor microcavities allows for the conversion of the circular polarization of an incoming laser beam into the orbital angular momentum of the transmitted light field. The process implies the formation of topological entities, a pair of optical half-vortices, in the intracavity field

Features of Nickel-Cadmium Batteries Recycling

The issue of operated-off alkaline nickel-cadmium batteries recycling is currently relevant due to a number of aspects: economic, environmental and social. It is most acute across the national corporation JSC Russian Railways. The article deals with some technological features of operated-off alkaline nickel-cadmium batteries recycling with valuable components being extracted (from the example of nickel-cadmium storage batteries of JSC ”RZD” rolling equipment). The results of leaching in Trilon B synthetic oxides solution, the presence of which is possible in the raw material being processed, are presented in the study. Based on the study of leaching processes of CdO, NiO, FeO, Femet and Fe2O3 in Trilon B solution, the dependence of complexing on the pH of the solution was revealed. The experimental site of the hydrometallurgical processing of the research center (OCGP IC) in the GMO KhMC PJSC ”Uralelectromed” was selected as the testing one for the technology proposed. As a raw material for the tests, a lot of negative lamellae packed in alkaline storage batteries of two different types were used. They were obtained as a result of preliminary drying and cutting at OOO Kursk factory ”Accumulator”. The particle size is 90% - 0.1 mm. The results obtained during the research allowed the author to formulate a hypothesis about the practical use of Trilon B for the processing of operated-off alkaline nickel-cadmium batteries with the extraction of valuable components having greater economic, environmental and social benefits compared to methods based on pyro metallurgy. Keywords: nickel-cadmium batteries, recycling, Trilon B, Russian Railways, hydrometallurgica

Creation, doubling, and splitting, of vortices in intracavity second harmonic generation

We demonstrate generation and frequency doubling of unit charge vortices in a linear astigmatic resonator. Topological instability of the double charge harmonic vortices leads to well separated vortex cores that are shown to rotate, and become anisotropic, as the resonator is tuned across resonance

Pattern manipulation via on-chip phase modulation between orbital angular momentum beams

An integrated approach to thermal modulation of relative phase between two optical vortices with opposite chirality has been demonstrated on a silicon-on-insulator substrate. The device consists of a silicon-integrated optical vortex emitter and a phase controlled 3 dB coupler. The relative phase between two optical vortices can be actively modulated on chip by applying a voltage on the integrated heater. The phase shift is shown to be linearly proportional to applied electrical power, and the rotation angle of the interference pattern is observed to be inversely proportional to topological charge. This scheme can be used in lab-on-chip, communications and sensing applications. It can be intentionally implemented with other modulation elements to achieve more complicated applications

Efficiency of the Left Atrial Appendage Thrombus Dissolution in Patients with Persistent Nonvalvular Atrial Fibrillation with Warfarin or Direct Oral Anticoagulants Therapy

Aim. Compare the incidence of the left atrial appendage (LAA) thrombus dissolution in patients with persistent nonvalvular atrial fibrillation receiving warfarin and direct oral anticoagulants (DOAC).Materials and methods. 68 patients with persistent nonvalvular atrial fibrillation were included in a retrospective study (age was 59.7±9.8 years, 60.3% men), in whom at least one repeated transesophageal echocardiographic examination was performed after detecting a thrombus. After detecting a thrombus in the LAA, 37 (54.4%) patients started or continued taking warfarin in doses that ensure the INR maintenance at the level of 2-3, 14 (20.6%) started or continued taking dabigatran at a dose of 150 mg 2 times/day, 14 (20.6%) started or continued taking rivaroxaban 20 mg 1 time/day and 3 (4.4%) started or continued taking apixaban 5 mg 2 times/day. Repeated transesophageal echocardiographic examination was performed on average 33.3±14.2 days after the first one.Results. Dissolution of a previously identified thrombus was found in 26 (83.9%) of 31 patients receiving DOAC and in 19 (51.4%) of 37 patients receiving warfarin (p=0.011). The logistic regression analysis showed that the chances of a thrombus dissolution in LAA while taking DOAC are 14.8 times (95% confidence interval [CI] was 2.469-88.72) higher than while taking warfarin. The size and the rate at which blood is expelled from the LAA also have an independent influence on the chances of thrombus dissolution. An increase in the size of a thrombus by 1 mm reduces the chances of a thrombus dissolution by 1.136 (95% CI was 1.040-1.244) times, and an increase in the rate of blood expulsion from the LAA by 1 cm/sec increases these chances by 1.105 (95% CI was 1.003-1.219) times.Conclusion. In the present study, the incidence of the LAA thrombus dissolution in patients with persistent nonvalvular atrial fibrillation while receiving DOAC was higher than while receiving warfarin

Broadness and specificity: ArdB, ArdA, and Ocr against various restriction-modification systems

ArdB, ArdA, and Ocr proteins inhibit the endonuclease activity of the type I restriction-modification enzymes (RMI). In this study, we evaluated the ability of ArdB, ArdA, and Ocr to inhibit different subtypes of Escherichia coli RMI systems (IA, IB, and IC) as well as two Bacillus licheniformis RMI systems. Furthermore we explored, the antirestriction activity of ArdA, ArdB, and Ocr against a type III restriction-modification system (RMIII) EcoPI and BREX. We found that DNA-mimic proteins, ArdA and Ocr exhibit different inhibition activity, depending on which RM system tested. This effect might be linked to the DNA mimicry nature of these proteins. In theory, DNA-mimic might competitively inhibit any DNA-binding proteins; however, the efficiency of inhibition depend on the ability to imitate the recognition site in DNA or its preferred conformation. In contrast, ArdB protein with an undescribed mechanism of action, demonstrated greater versatility against various RMI systems and provided similar antirestriction efficiency regardless of the recognition site. However, ArdB protein could not affect restriction systems that are radically different from the RMI such as BREX or RMIII. Thus, we assume that the structure of DNA-mimic proteins allows for selective inhibition of any DNA-binding proteins depending on the recognition site. In contrast, ArdB-like proteins inhibit RMI systems independently of the DNA recognition site

ОПРЕДЕЛЕНИЕ ВЕЛИЧИНЫ КОЭФФИЦИЕНТА ТЕПЛОПЕРЕДАЧИ МЕЖДУ ОТЛИВКОЙ ИЗ СПЛАВА АК7ч (A356) И ФОРМОЙ ИЗ ХОЛОДНОТВЕРДЕЮЩЕЙ СМЕСИ

Determined the iHTC (interface Heat Transfer Coefficient) between AK7ch (A356) aluminum alloy casting and no-bake mold. The heat transfer coefficient is determined by minimizing the error function values, representing the difference between the experimental and calculated temperature in the mold values during pouring, solidification and cooling. Determined the values of the heat transfer coefficient above the liquidus temperature of the alloy hL = 900 W/(m2·K) and below the solidus temperature hS = 600 W/(m2·K).Changing of the heat transfer coefficient within hL = 900÷1200 W/(m2·K) and hS = 500÷900 W/(m2·K) has no sufficient effect on the error value, and it remains within ~22 °C. It was shown the usability of the simplified approach using constant heat transfer coefficient h = 500 W/(m2·K), whereas error value is 23,8 °C. Changing of iHTC as function of height of the cylindrical ingot was experimentally confirmed. This owes to the different values of metallostatic pressure applied to the solid skin of the solidifying casting, leads to closer contact of the metal and mold in the bottom of the casting.Коэффициент теплопередачи h определяли между цилиндрической отливкой из алюминиевого сплава АК7ч (А356) и формой из холоднотвердеющей смеси на фурановом связующем путем минимизации значения функции ошибок, отражающей разницу между экспериментальными и расчетными значениями температур в форме при заливке, затвердевании и охлаждении. Выше температуры ликвидуса сплава (617 °С) найденное значение коэффициента теплопередачи равно hL = 900 Вт/(м2·К). Ниже температуры солидуса сплава (556 °С) коэффициент hS = 600 Вт/(м2·К). Изменение величины коэффициента теплопередачи в интервалах hL = 900÷1200 Вт/(м2·К) (выше температуры ликвидуса сплава) и hS = 500÷900 Вт/(м2·К) (ниже температуры солидуса) практически не влияет на величину функции ошибок, которая остается в пределах ~22 °С. Показано, что допустимо использование упрощенного подхода, когда задается постоянная величина h = 500 Вт/(м2·К), что приводит к ошибке 23,8 °С. Экспериментально, на примере цилиндрической отливки, подтверждено изменение коэффициента теплопередачи по высоте отливки, связанное с различной величиной металлостатического давления, действующего на возникающую твердую корку отливки во время ее затвердевания, что обусловливает более плотный контакт металла и формы в нижней части отливки