Organic pollution in culture water resulting from excess feed and metabolite buildup

Penaeus monodon postlarvae were subjected to increasing feed concentrations and their growth and survival rates were recorded. Measurements were made of dissolved organic matter, and ammonia and nitrite-nitrogen concentrations. Survival was highest at the lowest feeding level and decreased as feed concentration increased. It is concluded that although organic matter enriches the food supply for P. monodon postlarvae, at higher concentration levels it can pollute the culture water, which in turn leads to mass mortality of the postlarvae. Secondly, the survival rate of P. monodon postlarvae is directly related to dissolved organic matter concentration, oxygen tension, and ammonia-nitrogen concentrations in the culture water. Even at sublethal levels these adverse environmental conditions decrease the survival rate

Geological structure and prospects of noble metal ore mineralization of the Khayrkhan gabbroid massif (Western Mongolia)

An analysis of the distribution of noble metals in zones of sulfide mineralization makes it possible to justify the isolation of four ore-bearing horizons with a specific geochemical zonation. A rise in the gold content relative to palladium and platinum is observed from the bottom upwards along the section of the stratified series of gabbroids. The study of the mineral phases of sulphides and the noble minerals itself indicates the evolution of hydrothermal solutions, which determines the different activity and mobility of the fluid (mercury, tellurium, sulfur) and ore (copper, nickel, iron, platinum, gold and silver) components

PdZnAl Catalysts for the Reactions of Water-Gas-Shift, Methanol Steam Reforming, and Reverse-Water-Gas-Shift

Pd/ZnO/Al2O3 catalysts were studied for water-gas-shift (WGS), methanol steam reforming, and reverse-water-gas-shift (RWGS) reactions. WGS activity was found to be dependent on the Pd:Zn ratio with a maximum activity obtained at approximately 0.50, which was comparable to that of a commercial Pt-based catalyst. The catalyst stability was demonstrated for 100 hours time-on-stream at a temperature of 360ºC without evidence of metal sintering. WGS reaction rates were approximately 1st order with respect to CO concentration, and kinetic parameters were determined to be Ea = 58.3 kJ mol-1 and k0 = 6.1x107 min-1. During methanol steam reforming, the CO selectivities were observed to be lower than the calculated equilibrium values over a range of temperatures and steam/carbon ratios studied while the reaction rate constants were approximately of the same magnitude for both WGS and methanol steam reforming. These results indicate that although Pd/ZnO/Al2O3 are active WGS catalysts, WGS is not involved in methanol steam reforming. RWGS rate constants are on the order of about 20 times lower than that of methanol steam reforming, suggesting that RWGS reaction could be one of the sources for small amount of CO formation in methanol steam reforming

The increase in the incidence of syphilis in the Russian Federation: foreign migrant citizens as a risk group for the spread of the disease

Relevance. The incidence of sexually transmitted infections (STIs) has a serious impact on the health and lives of children, adolescents and adults. Syphilis, like most STIs, is a socially significant disease, while among the factors influencing the spread of this infection, migration processes, including labor migration, occupy a special place. Aims. To study syphilis in foreign migrants in the Russian Federation and individual subjects of the state in recent years. Material and methods. A retrospective epidemiological analysis of the incidence of syphilis among the population of the Russian Federation and foreign migrants was performed. The data from Federal Statistical Monitoring Form No. 9 and No. 34 was used with reference to STIs incidence in 2011–2022 in Russia and in its regions. Results. Among foreign migrant citizens, the incidence rates were higher than the Russian average: 1.5–2.0 times before 2020, and 4 times in 2021 and 2022. The proportion of registered cases of syphilis among foreign citizens in 2021 was 36.4%, significantly exceeding this figure not only in 2020 (18.2%), but also in previous years (16.7–21.2%). An increase in the number of foreign citizens with syphilis was observed in 2021 in all federal districts of the Russian Federation, while the number of syphilis cases detected in this contingent of people varied significantly between different regions of the Russian Federation. The main share (98.1%) in the structure of syphilis detected in foreign citizens was latent forms of the disease. Conclusions. The high level of detection of syphilis in foreign migrant citizens and the predominance of latent forms of the disease in this population represent a potential epidemiological danger of the spread of infection. In connection with the current situation, it seems necessary to develop and implement permanent and controlled algorithms for monitoring STIs in risk groups, including foreign migrant citizens