Optical study of strained double Ge/Si quantum dot layers

status: publishe

Транспортные свойства ориентированной и изотропной бумаги из одностенных углеродных нанотрубок

Buckypapers (BP) with carbon nanotubes (CNT) are very promising for a lot of applications, in which their high conductance, strength and small weight are required. In this work, isotropic BP were prepared using the solution-based deposition that includes the single walled carbon nanotubes (SWCNT) dispersion and the dispersion filtration from a solvent. To increase the BP conductivity, the orientation of the SWCNT bundles composing BP and a following iodine doping were applied. The method of extrusion through the narrow (300 µm) gap was used for the SWCNT orientation. The temperature dependences of conductance for isotropic, oriented and doped BP were studied to understand the effect of CNT alignment and the mechanism of transport through SWCNT BP. It was shown that bundle orientation increases the BP conductivity from ~103 S × cm-1 to ~104 S × cm-1, and iodine doping of oriented samples additionally increase the conductivity by an order. The fluctuation – assisted tunneling between CNT bundles was used to describe the mechanism of low temperature conductivity.Бумага (buckypaper – BP) из одностенных углеродных нанотрубок (ОУНТ) является перспективным материалом для использования в качестве компонентов микро- и наноэлектроники, в которых требуется высокая удельная электро- и теплопроводность, а также высокая удельная прочность. Изотропные образцы BP из ОУНТ сформированы фильтрацией дисперсии из ОУНТ для удаления растворителя. Для увеличения проводимости ВР проводилась ориентация ОУНТ вдоль выделенного направления, а также дополнительное легирование ОУНТ в парах йода. Ориентация ОУНТ осуществлялась с помощью экструзии через щель раствора из ОУНТ. Проведено сравнение температурных зависимостей электропроводности изотропных, ориентированных и легированных образцов ВР для выявления механизма проводимости и роли ориентации ОУНТ. Показано, что ориентирование пучков ОУНТ вдоль выделенного направления позволяет увеличить проводимость ВР с ~103 См/cм до ~104 См/cм, а легирование ориентированных образцов в парах йода увеличивает электропроводность еще на порядок. Механизм низкотемпературной проводимости по ВР описан флуктуационно-индуцированным туннелированием носителей заряда между пучками ОУНТ

Structural, Optical and Electronic Properties of the Wide Bandgap Topological Insulator Bi1.1Sb0.9Te2S

Successful applications of a topological insulator (TI) in spintronics require its bandgap to be wider then in a typical TI and the energy position of the Dirac point in the dispersion relations to be away from the valence and conduction bands. In this study we grew Bi1.1Sb0.9Te2S crystals and examined their elemental composition, structural, optical and electronic properties as well as the electronic band structure. The high structural quality of the grown crystals was established by X-ray diffraction and Raman spectroscopy. Angular resolved photoelectron spectroscopy demonstrated a near parabolic character of the valence and conduction bands and a direct bandgap of 0.36 eV. The dispersion relations also revealed a Dirac cone, confirming the topological insulator nature of this material, with the position of the Dirac point being 100 meV above the valence band maximum. Far infrared reflectivity spectra revealed a plasma edge and two phonon dips. Fitting these spectra with theoretical functions based on the Drude-Lorentz model allows determination of the high frequency dielectric constant (41.3), plasma frequency (936 cm−1) and the frequencies of two infrared phonons (177.7 cm−1 and 77.4 cm−1). © 2021 Elsevier B.V.The reported study was funded by RFBR, project number 19-29-12061 . The part of optical research was carried out within the state assignment of Ministry of Science and Higher Education of the Russian Federation (theme "Spin" No AAAA-A18-118020290104-2 and No AAAA-A19-119081990020-8 and theme "Electron" No AAAAA18-118020190098-5 ). The study was also supported by the Russian Science Foundation (Project No. 17-12-01047 ) in the part of the crystal growth and state assignment of ISP SB RAS ( 0306–2019-0007 ) and IGM SB RAS. The Raman measurements were partially supported by the grant of the Russian Foundation for Basic Research (Project No. 19-52-18008 ). This work is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through project-ID 258499086 – SFB 1170 (A01), the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter–ct.qmat Project-ID 390858490 – EXC 2147

Private Sector Union Density and the Wage Premium: Past, Present, and Future

The rise and decline of private sector unionization were among the more important features of the U.S. labor market during the twentieth century. Following a dramatic spurt in unionization after passage of the depression-era National Labor Relations Act (NLRA) of 1935, union density peaked in the mid-1950s, and then began a continuous decline. At the end of the century, the percentage of private wage and salary workers who were union members was less than 10 percent, not greatly different from union density prior to the NLRA

Raman scattering of Ge dot superlattices

Self-organised Ge dot superlattices grown by molecular beam epitaxy of Ge and Si layers utilizing Stranski-Krastanov growth mode were investigated by Raman spectroscopy. An average size of Ge quantum dots was obtained from transmission electron microscopy measurements. The strain and interdiffusion of Ge and Si atoms in Ge quantum dots were estimated from the analysis of frequency positions of optical phonons observed in the Raman spectra. Raman scattering by folded longitudinal acoustic phonons in the Ge dot superlattices was observed and explained using of elastic continuum theory

PRESCRIPTION OF MEDICATIONS INFLUENCING PROGNOSIS IN ATRIAL FIBRILLATION WITH ARTERIAL HYPERTENSION, CORONARY HEART DISEASE, CHRONIC HEART FAILURE, BY THE REGISTRY REKVAZA-CLINIC

Aim. To investigate on the prevalence of oral anticoagulation prescription (OAC), of β-blockers (BAB), angiotensin converting enzyme inhibitors (ACEi) or angiotensin receptor type II blockers (ARB), and statins in patients with atrial fibrillation (AF) comorbid with arterial hypertension (AH), coronary heart disease (CHD), chronic heart failure (CHF) at inpatient and out-patient stages of management, under framework of REKVAZA-CLINIC registry of cardiovascular diseases (CVD).Material and methods. Into the RECVAZA-CLINIC study, 3696 patients included, with diagnoses of AF, AH, CHD, CHF and combinations, hospitalized to NRCPM from 01.04.2013 to 31.12.2014, living in Moscow and Moscow Region. Of those, in current study 285 patients included (7,7%) with combinations of AF, AH, CHD, CHF. Prescription at outpatient stage of the OAC, BAB, ARB/ACEi and statins was assessed by case histories review. After the discharge, in 24,1±5,9 months, drug treatment was assessed by phone calls in 250 patients, and in 35,5±7,5 months — during office cardiologist visit in 113 randomly selected patients.Results. Mean age of the patients with combination of AF, AH, CHD and CHF was 73,9±10,0 y.o. (52,6% males). Myocardial infarction (MI) in anamnesis had 58,9% patients, stroke — 21,7%. At hospital stage, and in 2 and 3 years of follow-up, the prevalence of ACEi/ARB prescription did not decrease significantly, but statins were prescribed less comparing to in-patient stage (1,5 and 2,0 times), as OAC (1,2 and 1,4 times) and BAB (1,1 times in 3 years of follow-up). Combination of 4 drugs of the included classes, was the most commonly prescribed in-patient (68%) and most rare — before admission and in 3 years of post-discharge follow-up — 3,7 and 2,3 times more rare, than in inpatient stage. Postinfarction cardiosclerosis patients were less commonly prescribed the OAC at pre-admission stage (1,4 times) and BAB before admission and in hospital (1,2 times), as 2 years later (1,1 times). The ACEi/ARB were prescribed too rare at pre-admission and post-discharge stages (1,2 and 1,1 times), OAC for the period of 3 years (1,3 times). If comparing the patients with anamnesis of stroke, and with none, there were no significant differences of the drugs prescription frequency.Conclusion. By the data from in-hospital prospective registry RECVAZACLINIC, in patients with AF, AH, CHD, CHF at pre-admission stage, especially out-patient, the following drugs prescribed too rarely: OAC, BAB, ACEi/ARB, statins, that have beneficial impact on prognosis. It is important to increase outpatient physicians adherence to the combinations prescription for OAC, BAB, ACEi/ARB, statins in this category of patients

ORAL ANTICOAGULANTS IN AMBULATORY AND IN-HOSPITAL TREATMENT OF PATIENTS WITH ATRIAL FIBRILLATION ASSOCIATED WITH HYPERTENSION, ISCHEMIC HEART DISEASE AND CHRONIC HEART FAILURE: DATA FROM HOSPITAL REGISTRY RECVASA-CLINIC

Aim. To estimate the rate of oral anticoagulants (OAC) prescription, continuity of anticoagulant therapy in hospital and ambulatory stages along with treatment adherence in patients with atrial fibrillation (AF) associated with hypertension (HT), ischemic heart disease (IHD) and chronic heart failure (CHF) within the registry of cardiovascular diseases. Material and methods. The study included 285 patients with AF combined with HT, IHD and CHF from the hospital registry RECVASA-CLINIC (n=3696). The rate of OAC prescription was evaluated in ambulatory and in-hospital stages according to medical records. Out-patient treatment was estimated via phone contact in 250 participants that represented 96.2% of all survived patients during follow-up of 24.1Ѓ}5.9 months after discharge from hospital. Medical adherence was evaluated using Morisky-Green questionnaire. Results. Mean age of patients was 73.9Ѓ}10.0 years (male – 52.6), CHA2DS2-VASc and HAS-BLED score were estimated as 5.14Ѓ}1.50 и 1.59Ѓ}0.79, respectively. Contraindications to OAC treatment were registered in 34 (11.9%) patients. In pre-hospital stage patients with paroxysmal AF received OAK more rarely comparing to those with permanent and persistent AF (31.8%, 51.7 and 55%, respectively; р<0.05). The rate of OAC administration in pre-hospital stage, on discharge and after 24.1Ѓ}5.9 months follow-up period was 40.4%, 88.1% and 82%, respectively, whereas patients with previous stroke were prescribed OACs more frequently (in 49%, 92.5% and 83.7% of cases, respectively). Only 43% of study participants had good compliance to medical treatment (score of 4) according to Morisky-Green questionnaire. Conclusion. OACs were under prescribed in pre-hospital stage and after 2 years of follow-up in patients with AF combined with HT, IHD and CHF comparing with in-hospital period (40.4% and 82% vs 88.1%). Medical compliance according to Morisky-Green questionnaire was not enough (43%) in high-risk patients after discharge from hospital

CLINICAL AND VIROLOGICAL CHARACTERISTICS OF DISEASES ASSOCIATED WITH THE KAPOSI SARCOMA VIRUS

Abstract. The paper presents literature data and results of own studies on the Kaposi's sarcoma herpesvirus (KSHV) and its association with Kaposi's sarcoma (KS), the primary effusion lymphoma (PEL) and multicentric Kastleman disease (MCD). The obtained data show that all 3 main clinical forms of KS, diagnosed in Russia, are significantly associated with KSHV, though not always in 100% of cases. Distinct groups of persons with high prevalence of virus infection have been detected among patients with other forms of cancer and non-cancer diseases that may represent a risk factor for development of KS. It was found that the prostate, especially in patients with carcinoma of the prostate and KS could be an important localization of virus and intimate contact with these patients should be limited. For the first time in Russia HIV-negative case of PEL associated with KSHV had been diagnosed and studied in details. It was also demonstrated that isolates of KSHV, circulating in the country, belong to the two major genetic subgroups of the virus (A and C), a widely represented in the European countries and in the United States, which indicates a common origin of the virus in these countries. The current methodologies of KS’ treatment are also presented