Electromagnetic shape resonances of a dielectric sphere and radiation of portable telephones

The frequency band used by cellular telephones includes the eigenfrequencies of a dielectric sphere with physical characteristics close to those of a human head. Proceeding from the spatial features of the natural modes of such a sphere we propose an independent and clear evident accuracy test for the complicated numerical calculations which are conducted when estimating the potential hazard due to the use of cellular telephones, in particular, for the check of a proper handling of the electromagnetic shape resonances of a human head.Comment: 10 pages, 1 figure with 2 eps file

Aggregation of Malmquist Productivity Indexes

In this paper we extend the work of Färe and Zelenyuk (2003) to find a theoretically justified method of aggregating Malmquist Productivity Indexes over individual decision making units (firms, countries, etc.) into a group Malmquist Productivity Index. We also consider the aggregation of decomposed parts of the Malmquist Productivity Index to obtain a decomposition of the Malmquist Productivity Index for a particular group

Simultaneous Determination of Synthetic Food Dyes Using a Single Cartridge for Preconcentration and Separation Followed by Photometric Detection

A novel preconcentration/separation method for simultaneous sorption-spectrophotometric determination of anionic food dyes Sunset Yellow and Tartrazine is proposed. The method is based on preconcentration of the dyes using solid phase extraction on a cartridge filled with silica chemically modified with C16 groups from aqueous solution at pH 1 followed by elution with water/acetonitrile mixture containing 2 mmol·L−1 KH2PO4 adjusted to pH 3 with a step gradient of acetonitrile content. This elution allows quantitative separation of the dyes which makes their individual spectrophotometric determination possible. The detection limits for Tartrazine and Sunset Yellow are 0.15 and 0.11 μg·mL−1 and the linearity range is 2–20 μg·mL−1. The method is applied for analysis of beverages. The recovery of dyes is higher than 97% at the relative standard deviation not exceeding 10%

Photoelectric response in sandwich structures based on condensed layers of Ag2S quantum dots passivated with thioglycolic acid

The study is aimed at developing a technique for forming a structure with a Schottky barrier in the form of a mltilayer Al-Ag2S-ITO sandwich structure, which includes a condensate of colloidal Ag2S quantum dots passivated with thioglycolic acid molecules (Ag2S/TGA QDs). The spectral properties were studied using a USB2000+ spectrometer (Ocean Optics, USA) with a USB-DT light source (Ocean Optics, USA). Electrophysical and photoelectric properties of the structures were studied using a Keysight B1500A semiconductor device analyzer (Keysight tech, USA). The study of the temperature dependences of the properties in the temperature range from 300 to 360 K was carried out in a Shielded room (Faraday cage) placed in a muffle furnace. It was found that the conductivity of the Al-Ag2S-ITO structure is mostly governed by the Schottky barrier at the Al-condensed Ag2S QDs film junction. At the junction between the condensed Ag2S QDs film and Al, signs of the formation of a rectifying contact were found. Under the action of the optical radiation with a wavelength of 650 nm and less, which corresponds to the most probable exciton transition in the UV-Vis absorption of Ag2S/TGA QDs, an increase in the current was found for the negative branch of the J-V curve

Development of the Method of Evaluation of the Level of Environmental Safety of Housing Accommodation and Its Approbation

The method of estimating the level of ecological safety of a housing accommodation by environmental factors: physical, chemical, microclimatic and aesthetic is presented. Groups of danger factors in the structure of such a category of life quality as “Environmental safety of a dwelling house” are formed.The analysis of modern scientific studies showed that the vast majority of researchers use the survey method when assessing the quality of dwellings. This approach is justified in terms of the ease of processing the results. However, when using this approach, it is difficult to avoid subjectivity in assessment.Qualimetric tables have been compiled for the scoring assessment of the selected environmental hazards factors. Based on the values of the hazard factors scoring assessment and their weight determination, a formula is proposed for determining the numerical value of the integral indicator of the environmental safety of the dwelling.The application of the developed method allows:– assessing the existing environmental safety level of residential premises to manage its quality, in terms of both new construction and reconstruction;– justifying the choice of new architectural projects regarding environmental safety in the room;– estimating the cost of a premise when it is purchased on the primary or secondary market in the conditions of equivalence of all other parameters such as location, the state of the infrastructure of the district, etc

Mathematical Model of Determining A Risk to the Human Health Along with the Detection of Hazardous States of Urban Atmosphere Pollution Based on Measuring the Current Concentrations of Pollutants

A mathematical model of joint determining the risk to human health and the identification of hazardous states of the polluted urban atmosphere based on the measurement of current concentrations of pollutants was developed. The structure of the model includes two structural units. The input data for structural units are the results of measuring current concentrations of atmospheric pollutants at a checkpoint. The current risk to human health is calculated in the first unit, and recurrent states of atmosphere for early detection of dangerous pollution levels are determined in the second unit. A distinctive feature of the model is the use of only measurements of current concentrations of pollutants in the atmosphere at a control point. Meteorological or other information is not used. That is why the developed model is universal and can be used in any weather conditions and peculiarities of the urban infrastructure. The operation efficiency of the proposed model was tested experimentally using the example of measuring current concentrations of formaldehyde, nitrogen dioxide, and ammonia in the atmosphere of the typical urban infrastructure. It was established that the developed model makes it possible to determine the risk of immediate toxic effects and chronic intoxication for humans, caused by atmospheric pollution. It was proved experimentally that the proposed model makes it possible, together with the identification of relevant risks to human health, to detect hazardous states of the polluted atmosphere, in which pollutants are usually accumulated. It was established that determining the current probability of recurrent conditions of the polluted atmosphere makes it possible with various reliability degrees to detect the possible occurrence of negative effects of atmospheric pollution on human health 6–12 hours beforehan