Association of aerobic anoxygenic phototrophs and zebra mussels,Dreissena polymorpha,within the littoral zone of Lake Winnipeg

While nutrient loading has affected all levels of Lake Winnipeg’s ecology, its greatest influence has likely been on the microbial community. In addition to eutrophication, zebra mussels (Dreissena polymorpha) have recently invaded the ecosystem and threaten food web dynamics. Their filter-feeding predation and association with bacteria, specifically phototrophs, was investigated. A sampling trip to Lake Winnipeg in October 2017, focused on the isolation, enumeration, and identification of aerobic anoxygenic phototrophs in littoral water, sediment, and tissues of mussels. Gimli, Patricia, and Grand beaches, separated by >15 km across the South Basin, had similar bacterial counts when cultivated on rich organic, BG-11, purple non-sulphur, and K₂TeO₃-supplemented media. Culture-based enumeration on rich organic medium revealed 1.74% of heterotrophs from littoral waters were aerobic anoxygenic phototrophs, and represented 13.98% within sediments. In contrast, 0.48, 1.15, and 0.16% of cultured heterotrophs were aerobic anoxygenic phototrophs within zebra mussel gill, gut, and gonadal tissues, respectively. High-throughput sequencing of bacterial 16S V4 rDNA maintained similar trends in respective bivalve organs, where 0.22, 1.13, and 0.20% of total 16S genes belonged to these phototrophs. Several Sphingomonadaceae isolates were recovered from gut tissues, all with filamentous morphology large enough for predation. Bioaccumulation of metals was also studied in D. polymorpha. All tested associated aerobic anoxygenic phototrophs were capable of resisting the metalloid oxide tellurite. The consistent distribution of aerobic anoxygenic phototrophs within microbial communities across Lake Winnipeg, and their predominance in the gut tissues of zebra mussels suggested bacterial consumption by this invasive species.     

Multidimensional dU/dT Effect in High-Power Thyristors

Semiconductors - The procedure making it possible to take into account the influence of high-power thyristor design elements on its dU/dt parameter is described. A simple model is proposed, using...     

Synthesis of organoyttroxanealumoxanesiloxanes and preparation of glass and glass-ceramics on their base

We report the first synthesis of organoyttroxanealumoxanesiloxanes soluble in organic solvents. Their pyrolysis yields transparent glass-ceramic materials with a predetermined Al : Y : Si molar ratio [1]. We have studied the composition and properties of the organoyttroxanealumoxanesiloxanes and their pyrolysis products.     

Preparation of gold nanoparticles from the metal scrap

The possibility of producing gold nanoparticles from electronic waste (metal scrap) containing gold metal has been demonstrated. After dissolving the metal scrap in chloronitric acid, gold ions are concentrated from aqueous solutions by the flotoextraction method using cationic amphiphile; then, the resulting precursor is reduced in direct micelles of amphiphile. The obtained samples were characterized by the spectroscopic methods, X-ray phase analysis, transmission electron and atomic force microscopies. The catalytic properties of the synthesized gold nanoparticles have been investigated in the reaction of polymerization of pyrrole to polypyrrole.     

A Gas Generator Based on Porous Titanium in the Composition of Sealed-Off Plasma Focus Chambers

Instruments and Experimental Techniques - The use of a gas absorber based on porous titanium as a gas generator as part of a sealed electrovacuum device, that is, a plasma focus chamber, is...     

Conceptual approach to introduction of information technology into the field of simulation

We consider results of research by the faculty for design and production of radio equipment at Penza State University; the research was concerned with development of methods, models, algorithms, and software packages for investigating complex mechanical systems, technologies, and simulation of physical processes. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 7–11, May, 1999.     

Yeasts of the soil – obscure but precious

Pioneering studies performed in the nineteenth century demonstrated that yeasts are present in below‐ground sources. Soils were regarded more as a reservoir for yeasts that reside in habitats above it. Later studies showed that yeast communities in soils are taxonomically diverse and different from those above‐ground. Soil yeasts possess extraordinary adaptations that allow them to survive in a wide range of environmental conditions. A few species are promising sources of yeast oils and have been used in agriculture as potential antagonists of soil‐borne plant pathogens or as plant growth promoters. Yeasts have been studied mainly in managed soils such as vineyards, orchards and agricultural fields, and to a lesser extent under forests and grasslands. Our knowledge of soil yeasts is further biased towards temperate and boreal forests, whereas data from Africa, the Americas and Asia are scarce. Although soil yeast communities are often species‐poor in a single sample, they are more diverse on the biotope level. Soil yeasts display pronounced endemism along with a surprisingly high proportion of currently unidentified species. However, like other soil inhabitants, yeasts are threatened by habitat alterations owing to anthropogenic activities such as agriculture, deforestation and urbanization. In view of the rapid decline of many natural habitats, the study of soil yeasts in undisturbed or low‐managed biotopes is extremely valuable. The purpose of this review is to encourage researchers, both biologists and soil scientists, to include soil yeasts in future studies.     

Information features of multi-extremal functions for describing the functioning indicators of the components of information measurement systems

The questions are considered of estimating the information content of the extrema of multi-extremal functions which are of great practical significance for numerically solving a number of applied problems and, in particular, for estimating the spectral power density of steady-state random processes when choosing a numerical method for approximating the multi-extremal functions, etc. Translated from Izmeritel'naya Tekhnika, No. 8, pp. 19–21, August, 2000.     

Diagnosis of restorable components of special-purpose on-board data-acquisition systems

The diagnosis of restorable components of special-purpose on-board data-acquisition systems containing continuous and discrete devices is analyzed. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 17–19, July, 2000.