Carrier Recombination in Nitride-Based Light-Emitting Devices: Multiphonon Processes, Excited Defects, and Disordered Heterointerfaces.

We study recombination processes in nitride LEDs emitting from 270 to 540 nm with EQE ranging from 4% to 70%. We found a significant correlation between the LEDs' electro-optical properties and the degree of nanomaterial disorder (DND) in quantum wells (QWs) and heterointerfaces. DND depends on the nanoarrangement of domain structure, random alloy fluctuations, and the presence of local regions with disrupted alloy stoichiometry.

Quality Assessment of Processed Graphene Chips for Biosensor Application.

The quality of graphene intended for use in biosensors was assessed on manufactured chips using a set of methods including atomic force microscopy (AFM), Raman spectroscopy, and low-frequency noise investigation. It is shown that local areas of residues on the graphene surface, formed as a result of the interaction of graphene with a photoresist at the initial stage of chip development, led to a spread of chip resistance (R) in the range of 1-10 kOhm and to an increase in the root mean square (RMS) roughness up to 10 times, which can significantly worsen the reproducibility of the parameters of graphene chips for biosensor applications. It was observed that the control of the photoresist residues after photolithography (PLG) using AFM and subsequent additional cleaning reduced the spread of R values in chips to 1-1.

Investigation of the Morphology and Electrical Properties of Graphene Used in the Development of Biosensors for Detection of Influenza Viruses.

In this study, we discuss the mechanisms behind changes in the conductivity, low-frequency noise, and surface morphology of biosensor chips based on graphene films on SiC substrates during the main stages of the creation of biosensors for detecting influenza viruses. The formation of phenylamine groups and a change in graphene nano-arrangement during functionalization causes an increase in defectiveness and conductivity. Functionalization leads to the formation of large hexagonal honeycomb-like defects up to 500 nm, the concentration of which is affected by the number of bilayer or multilayer inclusions in graphene.

[Biologic markers and occupational monitoring of human exposure to exhaust gases of diesel engines].

The article presents results of studies covering changes in porphyrin and heme synthesis in lymphocytes of miners exposed to exhaust gases of diesel engines.

[Influence of various occupational factors on building workers].

The authors obtained data demonstrating that peculiarities of each building object, wide variety of building operations at various stages of construction and constantly renewed technologies and construction materials complicate unequivocal evaluation of work conditions in building industry and require a system of occupational monitoring for health state among all construction industry occupations, in accordance with work conditions and length of service.

Particle-bound benzene from diesel engine exhaust.

Objectives: The large surface area of the carbon core of diesel exhaust particles may contribute to the adsorption or condensation of such volatile carcinogenic organic compounds as benzene. The attention of this study focused on determining the distribution of benzene between the gas and particulate phases in the breathing zone of bus garage workers.

Methods: Benzene and suspended particulate matter were evaluated jointly in the air of a municipal bus garage.

[Study of the role of parents' occupation in children's mortality].

This study have been carried out to: a) investigate the prevalence of such occupational factors in parents which could be fatal to their children, and b) evaluate quantitatively the risk of mortality in infants caused by some leading diseases developed as a result of harmful occupational factors to which their parents had been exposed. During this work the data bank on infant mortality in Tallinn based on deaths registration in city archive for period 1968-1992 has been created. This bank includes the data on parents' occupation.