Bioprospecting for brewers: Exploiting natural diversity for naturally diverse beers

The burgeoning interest in archaic, traditional, and novel beer styles has coincided with a growing appreciation of the role of yeasts in determining beer character as well as a better understanding of the ecology and biogeography of yeasts. Multiple studies in recent years have highlighted the potential of wild Saccharomyces and non-Saccharomyces yeasts for production of beers with novel flavour profiles and other desirable properties. Yeasts isolated from spontaneously fermented beers as well as from other food systems (wine, bread, and kombucha) have shown promise for brewing application, and there is evidence that such cross-system transfers have occurred naturally in the past. We review here the available literature pertaining to the use of nonconventional yeasts in brewing, with a focus on the origins of these yeasts, including methods of isolation. Practical aspects of utilizing nondomesticated yeasts are discussed, and modern methods to facilitate discovery of yeasts with brewing potential are highlighted.     

X-ray determination of the stress state of rolling-stock components

For the example of steel rolling-stock components, the X-ray determination of the surface stress is considered, with special preparation of the surface at the point of measurement. The effectiveness of this method when using a prototype portable X-ray diffraction system is demonstrated. The operating principle of that system is as follows. In the presence of mechanical stress, the diffraction angle changes, and the diffraction peak is shifted in the recorded diffraction spectrum. The diffracted X-rays recorded by the detector are converted to digital information regarding their intensity distribution, by means of an analog–digital converter, and sent to a PC. STRESSCONTROLL software is developed for computer analysis of the diffraction spectra. That software displays the diffraction spectra in graphical form, controls the operation of the diffraction system, and calculates the stress by means of a database on metals and phases. The computer analysis includes determination of the spectrum’s center of gravity. The software separates out the background, approximates the data set as a curve, and permits precise calculation of the center of gravity of the smoothed profile. The surface stress is determined for fragments of a 20GL steel solebar cut from the edge of a bearing aperture of radius R55, Before testing, the fragments are subjected to normalization or to bulk–surface quenching. The surface stress is found to be close to zero for the normalized fragment, while considerable compressive stress is observed for the quenched sample. Thus, the shape of the diffraction peak and the level of surface stress are directly related to the microstructure of the steel. In that case, the X-ray determination of the surface stress may provide information regarding the state of the surface.     

Structure and Properties of High-Temperature Multilayer Hybrid Material Based on Vanadium Alloy and Stainless Steel

The present work is devoted to the development of new structural composite material having the unique complex of properties for operating in ultrahard conditions that combine high temperatures, radiation, and aggressive environments. A new three-layer composite tube material based on vanadium alloy (V-4Ti-4Cr) protected by stainless steel (Fe-0.2C-13Cr) has been obtained by co-extrusion. Mechanism and kinetics of formation as well as structure, composition, and mechanical properties of “transition” area between vanadium alloy and stainless steel have been studied. The transition area (13- to 22-µm thick) of the diffusion interaction between vanadium alloy and steel was formed after co-extrusion. The microstructure in the transition area was rather complicated comprising different grain sizes in components, but having no defects or brittle phases. Tensile strength of the composite was an average 493 ± 22 MPa, and the elongation was 26 ± 3 pct. Annealing at 1073 K (800 °C) increased the thickness of transition area up to 1.2 times, homogenized microstructure, and slightly changed mechanical properties. Annealing at 1273 K (1000 °C) further increased the thickness of transition area and also lead to intensive grain growth in steel and sometimes to separation between composite components during tensile tests. Annealing at 1073 K (800 °C) is proposed as appropriate heat treatment after co-extrusion of composite providing balance between diffusion interaction thickness and microstructure and monolithic-like behavior of composite during tensile tests.

     

Sixth graders’ evaluation strategies when reading Internet search results: an eye-tracking study

Eye-tracking technology was used to examine Internet search result evaluation strategies adopted by sixth-grade students (N?=?36) during ten experimental information search tasks. The relevancy of the search result’s title, URL, and snippet components was manipulated and selection of search results as well as looking into probabilities on the search result components was analysed. The results revealed that during first-pass inspection, students read the search engine page by first looking at the title of a search result. If the title was relevant, the probability of looking at the snippet of the search result increased. During second-pass inspection, there was a high probability of students focusing on the most promising search result by inspecting all of its components before making their selection. A cluster analysis revealed three viewing strategies: half of the students looked mainly at the titles and snippets; one-third with high probability examined all components; and one-sixth mainly focused on titles, leading to more frequent errors in search result selection. The results indicate that students generally made a flexible use of both eliminative and confirmatory evaluation strategies when reading Internet search results, while some seemed to not pay attention to snippet and URL components of the search results.     

Hydrogen embrittlement of steels: II. Effect of strength

The hydrogen embrittlement resistances of 35KhGM steel in states of different strengths are compared. The effect of strength on the fracture mechanism and kinetics in the steel during hydrogen embrittlement is demonstrated using a joint analysis of acoustic emission signals and stress-strain diagram during tension, metallography, and fractography.     

The influence of mechanical factors in alternating-current collector machines on level of radio noise

The influence of the mechanical state of the brush-collector contact on the level of radio noise in alternating-current collector machines is considered. Two methods to reduce the level of radio noise are offered: via a shift of current-carrying brush holders with respect to the radial position in the direction of rotation by half of the tangential size of the brush and application of lubricating brushes made on the basis of molybdenum disulfide.     

Stress corrosion cracking of zirconium cladding tubes: I. Proximate local SCC testing method

The mechanisms and kinetics of corrosion fracture of thin-wall cladding tubes of zirconium alloys in a methanol-iodine medium are determined by a direct comparison of the acoustic emission parameters with the characteristics of accumulated corrosion defects in a material during stress corrosion cracking tests. The main types of corrosion defects (nucleation, development, interaction) are revealed and quantitatively described. A general sequence of nucleation and development of corrosion defects is established for all types of tubes.