Photoluminescence imaging of single photon emitters within nanoscale strain profiles in monolayer WSe2_2

Local deformation of atomically thin van der Waals materials provides a powerful approach to create site-controlled chip-compatible single-photon emitters (SPEs). However, the microscopic mechanisms underlying the formation of such strain-induced SPEs are still not fully clear, which hinders further efforts in their deterministic integration with nanophotonic structures for developing practical on-chip sources of quantum light. Here we investigate SPEs with single-photon purity up to 98% created in monolayer WSe$_2$ via nanoindentation. Using photoluminescence imaging in combination with atomic force microscopy, we locate single-photon emitting sites on a deep sub-wavelength spatial scale and reconstruct the details of the surrounding local strain potential. The obtained results suggest that the origin of the observed single-photon emission is likely related to strain-induced spectral shift of dark excitonic states and their hybridization with localized states of individual defects.Comment: 8 pages, 4 figure

Практичні аспекти розпізнавання дефектів електричного типу за результатами аналізу розчинених у маслі газів

Проблематика. Розпізнавання типу дефектів у високовольтному маслонаповненому обладнанні, за результатами аналізу розчинених у маслі газів, із використанням значень критеріїв, які регламентовані чинним в Україні нормативним документом, не завжди дає змогу встановити правильний діагноз. З огляду на те, що постановка помилкового діагнозу може призвести до аварійного пошкодження обладнання, розглядаються шляхи підвищення достовірності розпізнавання типу дефекту. Мета дослідження. Підвищення достовірності розпізнавання типу дефектів високовольтного маслонаповненого обладнання за результатами аналізу розчинених у маслі газів із використанням чинного в Україні нормативного документа. Методика реалізації. Виконано порівняльний аналіз значень відношень газів і графічних образів для 31 різновиду дефектів електричного типу по 808 одиницях маслонаповненого обладнання. Наведено коротку характеристику та значення відношень газів і графічних образів для дефектів, розпізнавання яких викликає труднощі з використанням чинного в Україні нормативного документа. Результати дослідження. Встановлено, що в умовах реальної експлуатації значення діагностичних критеріїв, які використовуються для розпізнавання типу дефектів, можуть істотно відрізнятися від значень, що регламентуються чинними як в Україні, так і за кордоном нормативними документами. Більше того, для деяких дефектів значення відношень газів одночасно відповідають різним дефектам, а еталонні графічні образи відсутні, що значно ускладнює процедуру їх розпізнавання. Для усунення цих недоліків запропоновано графічні образи і діапазони значень відношень газів, які дають змогу розпізнавати більшу кількість різновидів дефектів порівняно з чинним в Україні нормативним документом – 31 замість 6. Висновки. Отримані і наведені в роботі діапазони значень відношень газів і графічні образи дефектів є діагностичною схемою, практичне використання якої дає можливість значно розширити діапазон дефектів, що розпізнаються за результатами аналізу розчинених у маслі газів, і тим самим підвищити експлуатаційну надійність високовольтного маслонаповненого обладнання

ASSESSMENT OF THE CURRENT STATE OF THE AGRICULTURAL STRUCTURE OF ARGENTINA

Background. Argentina is one of the largest and most developed socio-economic countries in Latin America. The use of modern agricultural technologies in the Argentine plains and new methods of shipping allowed Argentina to start exporting agricultural products to Europe. A series of commodity booms enriched Argentina and made it one of the largest economies in the world at the beginning of the 20th century. Purpose is to analyze and identify problems and prospects for the development of the agricultural structure in Argentina. Materials and methods. In the study, the authors used analytical materials of the UN Economic Commission and other international organizations on the countries of Latin America, reviews and reports of the Central Bank, the Institute of Statistics, the Ministry of Economy and Public Finance, the Ministry of Foreign Affairs. In this work, dialectical, systemic, historical, logical, formal-legal, comparative research methods were used. Results. Due to the abundance of appropriate land and natural resources, the favorable climate in most of the country and the generally low activity of pests, agricultural in Argentina is not particularly limited by natural conditions. However, there are a number of other factors that prevent Argentine farmers from fully operating as efficiently as possible. Conclusion. Argentina’s agro-industrial policy is quite contradictory. Despite the development of digital services and modern information technologies to support agricultural producers, the introduction of progressive export support programs, a fairly powerful infrastructure throughout the entire production cycle of agricultural products, the Argentine government from time to time resorts to using serious export barriers to maintaining the domestic market, which in general affects the Agar sector is not always positive

iPSC-derived neuronal models of PANK2-associated neurodegeneration reveal mitochondrial dysfunction contributing to early disease

Mutations in PANK2 lead to neurodegeneration with brain iron accumulation. PANK2 has a role in the biosynthesis of coenzyme A (CoA) from dietary vitamin B5, but the neuropathological mechanism and reasons for iron accumulation remain unknown. In this study, atypical patient-derived fibroblasts were reprogrammed into induced pluripotent stem cells (iPSCs) and subsequently differentiated into cortical neuronal cells for studying disease mechanisms in human neurons. We observed no changes in PANK2 expression between control and patient cells, but a reduction in protein levels was apparent in patient cells. CoA homeostasis and cellular iron handling were normal, mitochondrial function was affected; displaying activated NADH-related and inhibited FADH-related respiration, resulting in increased mitochondrial membrane potential. This led to increased reactive oxygen species generation and lipid peroxidation in patient-derived neurons. These data suggest that mitochondrial deficiency is an early feature of the disease process and can be explained by altered NADH/FADH substrate supply to oxidative phosphorylation. Intriguingly, iron chelation appeared to exacerbate the mitochondrial phenotype in both control and patient neuronal cells. This raises caution for the use iron chelation therapy in general when iron accumulation is absent

Design, Performance, and Calibration of CMS Hadron-Barrel Calorimeter Wedges

Extensive measurements have been made with pions, electrons and muons on four production wedges of the Compact Muon Solenoid (CMS) hadron barrel (HB) calorimeter in the H2 beam line at CERN with particle momenta varying from 20 to 300 GeV/c. Data were taken both with and without a prototype electromagnetic lead tungstate crystal calorimeter (EB) in front of the hadron calorimeter. The time structure of the events was measured with the full chain of preproduction front-end electronics running at 34 MHz. Moving-wire radioactive source data were also collected for all scintillator layers in the HB. These measurements set the absolute calibration of the HB prior to first pp collisions to approximately 4%

Design, Performance and Calibration of the CMS Forward Calorimeter Wedges

We report on the test beam results and calibration methods using charged particles of the CMS Forward Calorimeter (HF). The HF calorimeter covers a large pseudorapidity region (3\l |\eta| \le 5), and is essential for large number of physics channels with missing transverse energy. It is also expected to play a prominent role in the measurement of forward tagging jets in weak boson fusion channels. The HF calorimeter is based on steel absorber with embedded fused-silica-core optical fibers where Cherenkov radiation forms the basis of signal generation. Thus, the detector is essentially sensitive only to the electromagnetic shower core and is highly non-compensating (e/h \approx 5). This feature is also manifest in narrow and relatively short showers compared to similar calorimeters based on ionization. The choice of fused-silica optical fibers as active material is dictated by its exceptional radiation hardness. The electromagnetic energy resolution is dominated by photoelectron statistics and can be expressed in the customary form as a/\sqrt{E} + b. The stochastic term a is 198% and the constant term b is 9%. The hadronic energy resolution is largely determined by the fluctuations in the neutral pion production in showers, and when it is expressed as in the electromagnetic case, a = 280% and b = 11%

Energy Response and Longitudinal Shower Profiles Measured in CMS HCAL and Comparison With Geant4

The response of the CMS combined electromagnetic and hadron calorimeter to beams of pions with momenta in the range 5-300 GeV/c has been measured in the H2 test beam at CERN. The raw response with the electromagnetic compartment calibrated to electrons and the hadron compartment calibrated to 300 GeV pions may be represented by sigma = (1.2) sqrt{E} oplus (0.095) E. The fraction of energy visible in the calorimeter ranges from 0.72 at 5 GeV to 0.95 at 300 GeV, indicating a substantial nonlinearity. The intrinsic electron to hadron ratios are fit as a function of energy and found to be in the range 1.3-2.7 for the electromagnetic compartment and 1.4-1.8 for the hadronic compartment. The fits are used to correct the non-linearity of the e pi response to 5% over the entire measured range resulting in a substantially improved resolution at low energy. Longitudinal shower profile have been measured in detail and compared to Geant4 models, LHEP-3.7 and QGSP-2.8. At energies below 30 GeV, the data, LHEP and QGSP are in agreement. Above 30 GeV, LHEP gives a more accurate simulation of the longitudinal shower profile

Synchronization and Timing in CMS HCAL

The synchronization and timing of the hadron calorimeter (HCAL) for the Compact Muon Solenoid has been extensively studied with test beams at CERN during the period 2003-4, including runs with 40 MHz structured beam. The relative phases of the signals from different calorimeter segments are timed to 1 ns accuracy using a laser and equalized using programmable delay settings in the front-end electronics. The beam was used to verify the timing and to map out the entire range of pulse shapes over the 25 ns interval between beam crossings. These data were used to make detailed measurements of energy-dependent time slewing effects and to tune the electronics for optimal performance