Studying recovery processes in a strain-hardened Al–Mg–Mn–Fe–Si alloy

The material of a shell structure subjected to 20-year use under ambient conditions has been studied. The structure and mechanical characteristics of a strain-hardened AMg6 alloy, as well as the effect of subsequent holdings of this alloy for 10–3000 h at temperatures of 50, 70, 80, 100, 130, 150, 180, and 220°C, on changes in its dislocation structure and mechanical characteristics have been investigated. It has been shown that, in the structures under study, the AMg6 alloy has a cellular structure with a high density of dislocations and the ultimate strength σ_u = 445.5 ± 2.5 MPa, the proof stress σ_0.2 = 326.5 ± 3.5 MPa, and the relative elongation δ = 11.7 ± 0.5%. Polygonization in the alloy occurs at a temperature of 220°C and the initial stage of the recovery process corresponds to a temperature range of 50–100°С in which the softening process can be divided into two stages, i.e., stage (1) of active softening due to the interaction of point defects with each other and stage (2) of the stabilization of the characteristics of the alloy.     

Novel TTLL5 Variants Associated with Cone-Rod Dystrophy and Early-Onset Severe Retinal Dystrophy

Variants of the TTLL5 gene, which encodes tubulin tyrosine ligase-like family member five, are a rare cause of cone dystrophy (COD) or cone-rod dystrophy (CORD). To date, only a few TTLL5 patients have been clinically and genetically described. In this study, we report five patients harbouring biallelic variants of TTLL5. Four adult patients presented either COD or CORD with onset in the late teenage years. The youngest patient had a phenotype of early onset severe retinal dystrophy (EOSRD). Genetic analysis was performed by targeted next generation sequencing of gene panels and assessment of copy number variants (CNV). We identified eight variants, of which six were novel, including two large multiexon deletions in patients with COD or CORD, while the EOSRD patient harboured the novel homozygous p.(Trp640*) variant and three distinct USH2A variants, which might explain the observed rod involvement. Our study highlights the role of TTLL5 in COD/CORD and the importance of large deletions. These findings suggest that COD or CORD patients lacking variants in known genes may harbour CNVs to be discovered in TTLL5, previously undetected by classical sequencing methods. In addition, variable phenotypes in TTLL5-associated patients might be due to the presence of additional gene defects.     

13C NMR identification in crude oils of hydrocarbons bearing ethyl and n-alkyl substituents on their main chain

Assignment of ¹³C NMR signals of compounds with ethyl, n-propyl, n-butyl, n-amyl, and n-C₆₊ alkyl substituents in different positions of carbon chains in the spectra of saturated hydrocarbon fractions of crude oils and in the spectra of crude oils, taking into account the dependence of chemical shifts on the recording temperature, the concentration of the test solution. and the composition of the object of study, has been proposed. The capabilities of the ¹³C NMR technique as applied to determination of this almost unexplored group of hydrocarbons in crude oils have been discussed.     

A <Superscript>13</Superscript>C NMR study of crude oils: Detection of C<Subscript>15+</Subscript><Emphasis Type="Italic">trans</Emphasis>-1-methyl-2-alkylcyclopentanes

The presence of C₁₅₊ trans-1-methyl-2-alkylcyclopentanes in crude oil has been proven for the first time by means of the ¹³C NMR technique, and a procedure for their identification is described. It has been shown that these hydrocarbons represent a group of compounds bearing structurally different substituents, including the homologous series of trans-1-methyl-2-n-alkylcyclopentanes extended over a broad range of molecular masses. Their concentration in five samples of topped saturated petroleum hydrocarbons varies severalfold, with the maximal value being ～1 wt %. The ability of hydrocarbons from this group to form complexes with urea and thiourea was examined. The importance of the analysis of the temperature and concentration dependences of the chemical shifts of signals for the determination of the structure of previously unknown compounds in oil.     

A study of the formation modes of nanosized oxide structures of gallium arsenide by local anodic oxidation

Results obtained in a study of the influence exerted by the technological modes of local anodic oxidation (LAO) on the process in which nanosized oxide structures (NOSs) are formed on the surface of gallium arsenide are reported. The effect of the amplitude and duration of voltage pulses applied to the probesubstrate system, relative air humidity in the technological chamber, and amplitude of cantilever oscillations on the geometric parameters of gallium arsenide NOSs has been examined. It was found that raising the relative humidity from 60 to 90% results in a decrease in the threshold LAO voltage from 7.0 to 6.0 V. It is shown that raising the oscillation amplitude from 0.1 to 2.8 nm leads to a decrease in the NOS height from 3.20 ?? 0.34 to 1.10 ?? 0.13 nm and in the NOS diameter from 218.4 ?? 29.5 to 78.1 ?? 10.3 nm.