The Impact of Hydrogenation on Structural and Superconducting Properties of FeTe0.65Se0.35 Single Crystals

Properties of FeTe0.65Se0.35 single crystals, with the onset of critical temperature (Tconset) at 15.5 K, were modified via hydrogenation performed for 10–90 h, at temperatures ranging from 20 to 250 °C. It was found that the tetragonal matrix became unstable and crystal symmetry lowered for the samples hydrogenated already at 200 °C. However, matrix symmetry was not changed and the crystal was not destroyed after hydrogenation at 250 °C. Bulk Tcbulk, determined at the middle of the superconducting transition, which is equal to 12–13 K for the as grown FeTe0.65Se0.35, rose by more than 1 K after hydrogenation. The critical current density studied in magnetic field up to 70 kOe increased 4–30 times as a consequence of hydrogenation at 200 °C for 10 h. Electron paramagnetic resonance measurements also showed higher values of Tcbulk for hydrogenated crystals. Thermal diffusion of hydrogen into the crystals causes significant structural changes, leads to degeneration of crystal quality, and significantly alters superconducting properties. After hydrogenation, a strong correlation was noticed between the structural changes and changes in the parameters characterizing the superconducting state.

Analysis of the reasons for the formation of under-collar cracks in the bushing of medium-speed combustion engines

Вибрация цилиндровой втулки, вызванная перекладкой поршня, развивает колебания вдоль по длине втулки от бурта до основания и акустические колебания внутри втулки, которые приводят к возникновению растягивающих напряжений и деформаций в поверхностных слоях металла; при взаимодействии с водой создаются условия для диффузии водорода во втулку. Диффузия водорода повышает внутреннее давление, что вызывает растрескивание структуры металла под действием напряжений. Происходит деградация металла – снижение прочностных и пластических свойств. Причиной появления подбуртовых трещин и кавитационные разрушения цилиндровой втулки является усталость деградированного металла от «водородного растрескивания под напряжением» и действия циклических растягивающих напряжений. Для повышения долговечности втулок по подбуртовым трещинам необходимо: 1. Увеличение износостойкости скользящей поверхности втулки для стабилизации величины теплового зазора; 2. Повышение жесткости втулки за счет увеличения толщины втулки в подбуртовой зоне; 3. Применение метала втулки с малой чувствительностью к «водородному растрескиванию под напряжением» (замена чугуна с пластинчатой формой графита на сферическую). The vibration of the cylinder bushing caused by the piston displacement develops the vibrations along the length of the bushing from the collar to the base and acoustic vibrations inside the collar, which lead to tensile stresses and deformation in the surface layers of the metal; when interacting with water, conditions for the diffusion of hydrogen into the bushing are created. The diffusion of hydrogen increases internal pressure, which causes the cracking of the metal structure under stress. The degradation of the metal that is the decrease in strength and plastic properties occurs. The reason for the formation of under – collar cracks and cavitation destruction of the cylinder bushing is the fatigue of the degraded metal from "hydrogen stress cracking" and the action of cyclic tensile stresses. To increase the durability of the bushings along the under – collar cracks, it is necessary to: 1. Increase the wear resistance of the sliding surface of the bushing to stabilize the value of the thermal gap; 2. Increase the stiffening effect of the bushing by increasing the thickness of the bushing in the under – collar zone; 3. Apply the metal of the bushings with low sensitivity to "hydrogen stress cracking" (replace the cast iron with lamellar graphite for the spherical one).

Effect of Service Environmental Parameters on Electrochemical Corrosion Behavior of L80 Casing Steel

The corrosion behavior of L80 casing steel was studied in a simulating annulus environment using the electrochemical measurement method, immersion test, and tensile test under a high-temperature and high-pressure H2S/CO2 environment. The partial pressure of CO2 (PCO2), the partial pressure of H2S (PH2S), water content, and preloading stress remarkably affected the corrosion behavior of L80 steel. The influence of PCO2 on stress corrosion cracking (SCC) susceptibility has an inflection point of approximately 1.1 MPa. The SCC susceptibility reaches the maximum when the PCO2 is about 1.1 MPa. The SCC susceptibility has a positive correlation to PH2S and water content. The higher water content of the corrosion medium can increase the electrical conductivity of the corrosion medium and promote the corrosion of L80 steel, which can improve the diffusion of hydrogen into steel and promote the SCC of L80 steel. Preloading stress can promote local corrosion, thereby promoting SCC of steel under stress. The dislocation emergence point caused by preloading stress can accelerate the diffusion of hydrogen into steel and increase SCC susceptibility.

The Effect of Hydrogenation on Structure and Superconducting Properties of FeTe0.65Se0.35 Single Crystals

Single crystals of FeTe0.65Se0.35, with the onset of critical temperature (Tc) at 14 K, were hydrogenated for 10–90 hours at various temperatures, ranging from 20 to 250 oC. It is shown that tetragonal matrix becomes unstable and crystal symmetry is reduced for the crystals hydrogenated already at 200 oC despite that molecular impurities do not change matrix symmetry, unless the material is not destroyed under hydrogenation at 250 oC. Bulk Tc, takenat the middle of the transition, equal to about 12–13 K for the as-grown FeTe0.65Se0.35, increases by 1–2 K. The critical current density determined in magnetic field range of 0–70 kOe increases 4–30 times as a result of hydrogenation at 200 oC for 10 h. Electron paramagnetic resonance studies confirmed higher value of the bulk Tc for hydrogenated crystals. Thermal diffusion of hydrogen leads to substantial structural changes, causes degeneration of crystal quality, and significantly affects superconducting properties. A strong correlation was observed between the structural changes and changes in the parameters of the superconducting state for the hydrogenated crystals.

Investigation on the Emission and Diffusion of Hydrogen Sulfide during Landfill Operations: A Case Study in Shenzhen

This study investigated the emission and diffusion of hydrogen sulfide (H2S), as one of the odorous gases generated from landfills, in a municipal solid waste landfill of a south Chinese city. To this end, the flux of the H2S emissions in the working area of the landfill and its diffusion in the surrounding area were measured. The diffusion of the H2S was simulated at different wind speeds, wind directions, bare working areas of the landfill, heights of the landfill, and angles between the wind direction and the long side of the working area. The results indicated that the concentration of the H2S around the monitoring point ranged from 0 to 60 µg/m3, and the simulated data were consistent with the measured results. At a uniform wind direction, the pollution range of the H2S was narrow. Furthermore, with an increase in the height of the waste dump, the concentration of the H2S decreased in the working area but rose in the surrounding area. Notably, when the angle between the long side of the working area and the wind direction was 0°, the H2S largely spread along the extension cord of the long side of the working area. When the angle increased to 90°, the influence range of the H2S extended significantly. The working area in the landfill site should be regulated based on the monitored data to reduce the effect of this harmful gas on the living environment, and the health of the landfill staff and nearby residents.

Comparison of Hydrogen Thermal Desorption Analysis Curves of Electron-Irradiated F82H and Creep-Ruptured Pure Fe Obtained by Experiments and Simulations

Herein, we compared thermal desorption analysis (TDA) curves obtained by conducting experiments and simulations. In addition, we discussed the validation of our simulations and trapping sites of hydrogen atoms. In as-received F82H, when the samples contained solute atoms, grain boundaries, dislocations, and precipitates, the experimental curve corresponded to the simulated curve. In positron annihilation lifetime (PAL) measurements, di-vacancies were detected in the electron-irradiated F82H. When we changed the growth and the concentration of vacancy-type defects during temperature increase using the rate theory, the simulation results agreed with experiment results. In creep-ruptured Fe, only dislocations were detected by the PAL measurements. However, the existence of a type of defect, which was related to grain boundaries, must be assumed to fit the simulation curve to the experimental one. In the next step, the diffusion of hydrogen atoms on grain boundaries should be added to simulation program.

Hydrogen Peroxide, Water Channels, and Tissue Injury

Water channels, also known as aquaporins, were discovered by Peter C. Agre, the recipient of the 2003 Nobel Prize in Chemistry. In addition to facilitating transport of water, these channels have been shown to also mediate the diffusion of hydrogen peroxide across cell membranes and consequently control the biological functions of this important reactive oxygen species. Findings from multiple recent studies published in highly influential journals have further advanced our understanding on how to control the biological effects of hydrogen peroxide via targeting specific water channels. REFERENCES Hopkins RZ. Hydrogen Peroxide in biology and medicine: an overview. React Oxyg Species (Apex) 2017; 3(7):26–37. doi: https://dx.doi.org/10.20455/ros.2017.809. Bienert GP, Moller AL, Kristiansen KA, Schulz A, Moller IM, Schjoerring JK, et al. Specific aquaporins facilitate the diffusion of hydrogen peroxide across membranes. J Biol Chem 2007; 282(2):1183‒92. doi: https://dx.doi.org/10.1074/jbc.M603761200. Miller EW, Dickinson BC, Chang CJ. Aquaporin-3 mediates hydrogen peroxide uptake to regulate downstream intracellular signaling. Proc Natl Acad Sci USA 2010; 107(36):15681‒6. doi: https://dx.doi.org/10.1073/pnas.1005776107. Watanabe S, Moniaga CS, Nielsen S, Hara-Chikuma M. Aquaporin-9 facilitates membrane transport of hydrogen peroxide in mammalian cells. Biochem Biophys Res Commun 2016; 471(1):191‒7. doi: https://dx.doi.org/10.1016/j.bbrc.2016.01.153. Hara-Chikuma M, Chikuma S, Sugiyama Y, Kabashima K, Verkman AS, Inoue S, et al. Chemokine-dependent T cell migration requires aquaporin-3-mediated hydrogen peroxide uptake. J Exp Med 2012; 209(10):1743‒52. doi: https://dx.doi.org/10.1084/jem.20112398. Hara-Chikuma M, Satooka H, Watanabe S, Honda T, Miyachi Y, Watanabe T, et al. Aquaporin-3-mediated hydrogen peroxide transport is required for NF-kappaB signalling in keratinocytes and development of psoriasis. Nat Commun 2015; 6:7454. doi: https://dx.doi.org/10.1038/ncomms8454. Satooka H, Hara-Chikuma M. Aquaporin-3 controls breast cancer cell migration by regulating hydrogen peroxide transport and its downstream cell signaling. Mol Cell Biol 2016; 36(7):1206‒18. doi: https://dx.doi.org/10.1128/MCB.00971-15. Montiel V, Bella R, Michel LYM, Esfahani H, De Mulder D, Robinson EL, et al. Inhibition of aquaporin-1 prevents myocardial remodeling by blocking the transmembrane transport of hydrogen peroxide. Sci Transl Med 2020; 12(564). doi: https://dx.doi.org/10.1126/scitranslmed.aay2176. Steinhorn B, Sorrentino A, Badole S, Bogdanova Y, Belousov V, Michel T. Chemogenetic generation of hydrogen peroxide in the heart induces severe cardiac dysfunction. Nat Commun 2018; 9(1):4044. doi: https://dx.doi.org/10.1038/s41467-018-06533-2. Hara-Chikuma M, Tanaka M, Verkman AS, Yasui M. Inhibition of aquaporin-3 in macrophages by a monoclonal antibody as potential therapy for liver injury. Nat Commun 2020; 11(1):5666. doi: https://dx.doi.org/10.1038/s41467-020-19491-5. Hansson GK. Inflammation, atherosclerosis, and coronary artery disease. N Engl J Med 2005; 352(16):1685‒95. doi: https://dx.doi.org/10.1056/NEJMra043430. Perry VH, Nicoll JA, Holmes C. Microglia in neurodegenerative disease. Nat Rev Neurol 2010; 6(4):193‒201. doi: https://dx.doi.org/10.1038/nrneurol.2010.17.