Superradiant Emission from Coherent Excitons in van Der Waals Heterostructures

Recent advancements in isolation and stacking of layered van der Waals materials have created an unprecedented paradigm for demonstrating varieties of 2D quantum materials. Rationally designed van der Waals heterostructures composed of monolayer transition-metal dichalcogenides (TMDs) and few-layer hBN show several unique optoelectronic features driven by correlations. However, entangled superradiant excitonic species in such systems have not been observed before. In this report, it is demonstrated that strong suppression of phonon population at low temperature results in a formation of a coherent excitonic-dipoles ensemble in the heterostructure, and the collective oscillation of those dipoles stimulates a robust phase synchronized ultra-narrow band superradiant emission even at extremely low pumping intensity. Such emitters are in high demand for a multitude of applications, including fundamental research on many-body correlations and other state-of-the-art technologies. This timely demonstration paves the way for further exploration of ultralow-threshold quantum-emitting devices with unmatched design freedom and spectral tunability.     

Heat Propagation in Deformable Polycrystalline Metals with Grain-Size Variation

Russian Engineering Research - Attention focuses on the heat propagation in metal polycrystals where the grain or subgrain size affects the strengthening—as a result of surface plastic...     

Influence of Cu<Superscript>2+</Superscript> ions on structural and magnetic properties of NiZn ferrites

The paper is devoted to the preparation of NiZn ferrite with small substitutions of copper by means of ceramic technology. The influence of small Cu substitution on the microstructural and magnetic properties of NiZn ferrites have been analysed by means of various experimental methods and interpreted from the point of view of preparation technology optimisation and possible applications of such materials. A strong correlation between the substituent content and resulting properties has been observed, thus allowing preparation of material with the properties tailored for any particular application.     

Problem on estimation of the content of <Superscript>131</Superscript>I in milk in the “iodine” period of the Chernobyl accident

Measurements of the beta-activity of milk, serving as the main source of information on the radioactive contamination of the environment by the iodine isotope ¹³¹I, carried out on a DP-100 radiometer in the early post-Chernobyl period (1986) in Belarus, have been mathematically simulated. The results obtained allow the conclusion that the indicated measurements should be analyzed again with consideration for all of the nuclides present in milk. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 6, pp. 102–108, November–December, 2007.     

Annular slot-coupled dielectric resonator antenna

An annular slot-coupled dielectric resonator antenna is investigated experimentally. As compared with the previous rectangular-slot version, the new configuration offers a much wider bandwidth of 18%. The return loss, radiation patterns, and antenna gain of the configuration have been measured and are discussed     

A wideband low noise amplifiers design incorporating the CMRC circuitry

An impedance bandwidth enhancement technique for tuning a low noise amplifier (LNA) is presented. With the use of the compact microstrip resonant cell (CMRC) at the emitter pins of a bipolar junction transistor (BJT), the impedance bandwidth achieved is about 95%, for a simple single stage amplifier design. The LNA attains a gain of about 15 dB; also a low noise figure of 1.16 dB at 2.1GHz and an average noise figure of about 1.5 dB across the operation bands have been achieved.     

Screening for hepatitis C of hospital personnel at the Szent László Hospital of Budapest

The health-care workers are known to be at risk of occupational transmission of blood-borne viruses. The goal of the investigation was to determine the prevalence of hepatitis C virus (HCV) antibody and the occupational risk of HCV transmission among personnel at the Central. Hospital for Infectious Diseases, Budapest, Hungary. Serum samples of 409 health-care workers were tested for antibody to HCV with second and third generation ELISA-s and anti-HCV positive samples were confirmed with Western Blot Line EIA. A total of 10 (2.4%) of the health-care workers were confirmed to be anti-HCV positive. The prevalence of anti-HCV increased with advancing age: zero under 20 yr age group (N = 0/15), 0.9% in 21-30 yr age group (N = 1/112), 1.8% in 31-40 yr age group (N = 2/111), 3.1% in 41-50 yr age group (N = 3/96) and 4.0% in above 50 yr age group (N = 3/75). We found anti-HCV positive hospital worker in 9 out of 17 departments. The prevalence of hepatitis C antibody was 7.1-1.9% among the personnel of internal departments, pathology, intensive care unit and pediatric departments. No anti-HCV positive health-care worker was found in the surgery and laboratories. None of the physicians tested was seropositive for HCV. Eight of the nurses, one of the sanitary personnel and one pathological technician were seropositive for HCV. Two nurses developed a chronic C hepatitis after a needlestick accident. CONCLUSIONS: 1. The hospital personnel is at risk for HCV infection. 2. The occupational risk of HCV infection increases with age but the risk is considerable lower than that of hepatitis B infection. 3. The occupational risk is highest among the workers of the chronic internal department, pathology and intensive care unit. 4. The nurses are at higher risk of HCV infection than the physicians. 5. The needlestick injury is associated with an increased risk for acquiring HCV infection.     

A Study of The Moisture-Uptake Kinetics of a Hygroscopic Pharmaceutical Powder

The moisture-uptake kinetics of a hygroscopic powder, sodium heparin contained in a cylindrical container, was determined using a novel moisture-uptake measuring device under a constant convective air flow. The amount of moisture uptake increased with the increase in the relative humidity of the air. The effect of powder-bed height on the total amount of moisture uptake was found to be significant only at the highest relative humidity (75%) evaluated in this study. However, the percent of weight increase of the powder as a result of moisture uptake decreases as the height of the powder bed increases. The results of this study are explained by the dynamic nature of the moisture-uptake process associated with the instrument.     

Amyloid light-chain amyloidosis with primary involvement of the cardiorespiratory system--2 case reports

The authors describe the cases of two women suffering from AL amyloidosis with affection of the heart muscle in particular. In one of the patients there were also massive amyloid deposits in the lungs which is an exceptional finding. The observations confirm the adverse prognosis of amyloidosis, the rapid progression of the disease after the onset of symptoms of cardiac failure. The first cardial manifestation in both patients were palpitations. The first patient, but not the second one, had a myeloma confirmed on necropsy.