Aharonov-Bohm interference in quantum ring exciton: effects of built-in electric fields

We report a comprehensive discussion of quantum interference effects due to the finite structure of excitons in quantum rings and their first experimental corroboration observed in the optical recombinations. Anomalous features that appear in the experiments are analyzed according to theoretical models that describe the modulation of the interference pattern by temperature and built-in electric fields.Comment: 6 pages, 7 figure

Development of a Mineral Binding Material with Elevated Content of Red Mud

The object of present research is the technology of production of mineral binding materials of low-temperature (Tmax=1100 ºC) roasting of the romancement type with maximal possible use of waste from alumina production – red mud as a technogenic raw material. We employed as research methods a combination of computer calculations using the new software, modern physical-chemical methods of analysis and standardized testing of the properties of raw materials and binding materials.Based on computer calculations, applying the developed software «RomanCem», we performed analysis of dependence of the concentration of red mud in 3-component blends on the number of hydraulic module of the binder NM=1.1–1.7. We determined compositions of blends containing red mud of 27.0–27.5 % by weight (versus 3–5 % by weight in the technology of Portland cement) for the production of a hydraulic mineral binder at a maximum temperature of roasting 1100 ºC (versus 1400–1450 ºC for Portland cement) with improved indicators of strength at 18–22 MPa (versus 5–10 MPa for romancement). Effectiveness of our technique is defined by a comprehensive solution to the issues of ecology (due to reducing the volumes of waste accumulation), resource saving (through a replacement with waste of part of the raw materials of natural origin), and technology of binders (due to obtaining a product of the romancement type with improved indicators of properties). We demonstrated the features of phase composition and properties of the binders based on the systems of carbonate component with polymineral clay, quartz powder and red mud

Aspects of Making of a Composite Material When Using Red Mud

A composite material was developed with the polymeric binder at the elevated concentration of a technogenic raw material, 75 % by weight of red mud, as the filler. Dependence of indicators of composite properties on the content of the filler at the differentiation of varieties of polymer binders was established. When applying the binder Acronal 290 D, the water absorption minimum is 3.2–3.5 % by weight, the maximum is 5.0–5.3 % by weight. When applying Pliolite AC-4, the water absorption minimum is 0.83–0.96 % by weight, the maximum is 3.0–3.2 % by weight. When replacing the binder from the aqueous dispersion with the varnish dispersion, it is observed that water absorption level decreases by two times, but the character of dependence of this indicator on concentration of the filler remains unchanged. Analysis of hydrophobicity as a factor of improvement of operational properties of the composite showed that the maximum values of wetting angle of 130–136 degrees are registered at the concentration of the filler of 75 % by weight.We established features of the porous structure of the composite as a factor of influence on its properties. Total porosity and development of its varieties depend on the type of the polymeric binder. Indicators of total porosity are at the level of 9.3–11.8 % against 8.6–23.9 %, and the indicators of open porosity are at a significantly lower level of 0.96–3.15 versus 3.49–5.32 over the same range of changes in the concentrations of the filler when using Pliolite AC-4 compared to Acronal 290 D.It was shown that the developed material is distinguished by decorative (red color) and physical-technical characteristics that are important for modern architecture, which contributes to solving comprehensively the tasks on extending the range of composites and on the industrial waste disposal

Application of Varieties of Technogenic Raw Materials in Cement TECHNOLOGY

The possibility of manufacturing a mineral binder using large-tonnage waste from other industries has been studied. The object of the research are mixtures for the manufacture of cement clinker based on systems of chalk – clay – scope of paper production and chalk – clay – husks of rice processing. At the same time, urgent tasks of developing the raw material base for cement production and resource conservation were solved. The development of new initial mixtures was carried out taking into account the peculiarities of the chemical and mineralogical composition of varieties of technogenic raw materials. According to the chemical composition, rice alkali is characterized by a content of 15.6 wt. % SiO2 with a large quantitative ratio of SiO2:Al2O3=65.2 and a small amount of alkaline earth and alkaline oxides. Scop differs from alkali in a large amount of CaO (25.8 wt. %), a lower content of SiO2 at a quantitative ratio of SiO2:Al2O3=1.3. In this case, there are quantitative ratios of oxides CaO:SiO2=2.5, CaO:Al2O3=3.3, CaO:SiO2:Al2O3=3.3:1.4:1, which determine the probable phase transformations during firing. The main rock-forming mineral in rice husks is amorphous silica; Scope is marked by the presence of crystalline phases of calcite, quartz, and kaolinite. The analysis of the possible content of the studied wastes and the determination of the compositions of the raw mixtures were carried out using the computer program «Clinker». Analysis of computer calculations and experiments indicates the possibility of reducing by 11–16 wt. % consumption of natural raw materials in the composition of mixtures for the manufacture of clinker in comparison with the known production composition. According to X-ray phase analysis, the features of the development of crystalline phases during the firing of mixtures using varieties of technogenic raw materials at a maximum temperature of 1400 ºС were established. Based on the data of technological testing, the differences in indicators of binding properties were determined - the setting time of cement when used in the composition of raw mixtures of rice husk and paper scope

Sensitivity of the skin test with tuberculous allergen in TB/HIV patients

The sensitivity of skin test with tuberculous allergen in TB/HIV patients has need studied (n = 36) depending on the immune deficiency and the character of tuberculous inflammation. The comparison group included patients with HIV infection and no tuberculosis (n = 54). The test results in HIV patients but without tuberculosis and in the patients with the concurrent condition are directly connected to the degree of immune deficiency. In the patients with HIV infection and progressing tuberculosis the negative results of the test are due to secondary anergy. The patients with severe and expressed immune deficiency the negative results do not exclude the activeness of the infection, thus patients with CD4 level up to 350 + cl/mcl and negative results can be referred as a group of high risk of developing tuberculosis

VERTICAL VARIATIONS IN THE PRINCIPLE CHEMICAL-PROPERTIES OF THE BLACK-SEA IN THE AUTUMN OF 1991

Basin-wide principal hydrochemical data for the upper 500 m of the Black Sea were obtained at a total of 197 stations during a multi-ship, multi-institutional, HYDROBLACK-91 cruise in September 1991. Only offshore stations, 38 from the 1991 joint cruise, 5 from R/V Knorr (1988),16 from R/V Atlantis-II (1969), and 9 from R/V Bilim (1990) cruises, are considered in conjunction with the present and past data as a function of potential density rather than depth. The oxycline, coinciding with the upper boundary of the permanent pycnocline (sigma(THETA) = 14.2-14.3), extended down to the sigma(THETA) = 15.3-15.4 surfaces during warm periods (June-September) and to the sigma(THETA) = 15.75 surface during spring periods. The lower boundary of the oxycline (O2 less-than-or-equal-to 20 muM) has remained constant within the last two decades when past and present spring data are considered, but has risen by 0.30 density units when late summer-autumn data are considered. Independent of the geographical location, the base of the transition layer was established at the sigma(THETA) = 16.15-16.20 surfaces where H2S greater-than-or-equal-to 5 muM. Nitrate and phosphate reached their maxima at sigma(THETA) = 15.3-15.4 surfaces and then decreased steadily with different slopes until the sigma(THETA) = 15.85-15.95 surfaces. At the anoxic interface, phosphate concentration increases about 10 fold from approximately 0.02-0.5 muM at the sigma(THETA) = 15.85-15.90 surface to 4-6 muM at the sigma(THETA) = 16.15-16.20 surface. Comparison with the data from the 1970's suggests that both the maximum values and the depth integrated mass of nitrate (g NO3-N/m2) between the sigma(THETA) = 14.2 and 16.0 surfaces have increased 2-3 fold, and the density surface where the NO3 maximum is established has shifted by 0.30 units in the late 1980's

Theoretical and Experimental Study of New Photochromic Bis-Spiropyrans with Hydroxyethyl and Carboxyethyl Substituents

Two new asymmetrical bis-spiropyrans with nonequivalent spiropyran units have been investigated. Hydroxyethyl and carboxyethyl substituents have been used to improve thermal stability of the photoinduced merocyanine forms of the bis-spiropyrans. 2-Hydroxyethyl substituted compound is characterized by 4 times more stable merocyanine isomer. 2-Carboxyethyl substituent in the hetarene part enables chelation by metal ions and controllably stabilizes the merocyanine from thermal decay. As a result of theoretical modeling and photochemical experiments, it was shown that obtained compounds are perspective prototypes for multistate light-driven switches with improved stability of photoinduced forms