Generic Lung Function medical gas mixture 1

Abstract A sealed reciprocating tribometer has been used to study the influence of different gaseous environments on the friction and wear properties of AISI52100 bearing steel at atmospheric pressure and 25 °C. Helium, argon, hydrogen, carbon dioxide and nitrogen all give high friction and wear, suggestive of very little, if any tribofilm formation under the conditions studied. Dry air and oxygen also give high friction, slightly lower than the inert gases, but produce extremely high wear, much higher than the inert gases. This is characteristic of the phenomenon of “oxidational wear”. The two gases ammonia and carbon monoxide give relatively low friction and wear, and XPS analysis indicates that this is due to the formation of adsorbed ammonia/nitride and carbonate films respectively. For the hydrocarbon gases studied, two factors appear to control friction and wear, degree of unsaturation and molecular weight. For the saturated hydrocarbons, methane and ethane give high friction and wear but propane and butane give low friction after a period of rubbing that decreases with molecular weight. The unsaturated hydrocarbons all give an immediate reduction in friction with correspondingly low wear. Raman analysis shows that all the hydrocarbons that reduce friction and wear form a carbonaceous tribofilm on the rubbed surfaces. Graphical Abstract

Abstract licence: CC BY

The quantification of the effects of space radiation for manned spaceflight can be approximated by nanodosimetric measurements. For the development of nanodosimetric detectors, a Monte Carlo model for ion mobility and diffusion for characteristic electric fields is presented. This model can be used to describe the interactions of ions in their parent gas based solely on commonly known input parameters, such as the ionization potential, kinetic diameter, molar mass, and polarizability of the gas. A model for approximating the resonant charge exchange cross section has been proposed, requiring only the ionization energy and mass of the parent gas as input parameters. The method proposed in this work was tested against experimental drift velocity data for a wide range of gases (helium, neon, nitrogen, argon, krypton, carbon monoxide, carbon dioxide, oxygen, propane). The transverse diffusion coefficients were compared to experimental values for helium, nitrogen, neon, argon, and propane gas. With the Monte Carlo code and resonant charge exchange cross section approximation model presented in this work, it is now possible to calculate an estimate of the drift velocities, transverse diffusion, and thus the ion mobility of ions in their parent gas. This is essential for further nanodosimetric detector development, as those parameters are often not well known for the gas mixtures used in nanodosimetry.

Abstract licence: CC BY-NC-ND

Formic acid is obtained as a byproduct of biomass pyrolysis and is used as a liquid organic hydrogen carrier due to its low decomposition temperature, enabling hydrogen production under mild conditions with noble metals. The decomposition of FA in the vapor phase using different rhenium phases (metal, carbide, and oxide) supported on graphite and carbon nanotubes was studied within a temperature range of 80–220 °C, in a fixed‐bed reactor with a space velocity of 651 mL g cat h −1 . The catalysts were characterized by N 2 adsorption–desorption, H 2 ‐temperature‐programmed reduction, transmission electron microscopy, temperature programmed desorption‐ammonia, temperature programmed reaction‐methanol, X‐ray diffraction, and X‐ray photoelectron spectroscopy. Graphite‐supported catalysts achieved higher activity than carbon nanotube‐supported ones, due to the higher rhenium dispersion on graphite. Catalytic reactions revealed that ReC/G exhibited superior performance at lower temperatures per active site, attributed to the rhenium carbide phase. High selectivity toward CO 2 was observed across all catalysts, except for ReOx/G at lower temperatures, where differences in active site characteristics likely influenced performance. ReC/G displayed the highest intrinsic activity, highlighting rhenium carbide as a more active phase than metallic or oxide rhenium.

Abstract licence: CC BY

Chiral spirocyclic skeletons have found widespread applications in asymmetric catalysis, drug discovery, and functional materials due to their rigid three-dimensional architecture and excellent stereochemical stability. However, the structural diversity of accessible spiro frameworks remains limited, constraining their broader utility and functional development. For instance, chiral (N, N)-spiroketals represent a promising class of scaffolds with potential application in asymmetric catalysis and are frequently encountered in natural products and biologically active compounds, yet their efficient synthesis is still underdeveloped. Herein, we present a Pd-catalyzed cascade enantioconvergent aminocarbonylation and intramolecular dearomative nucleophilic aza-addition that enables the efficient synthesis of chiral (N, N)-spiroketal. This formal [3 + 1 + 1] spiroannulation employs racemic quinazoline-derived heterobiaryl triflates, carbon monoxide, and amines to deliver an array of (N, N)-spiroketal in high yields and excellent enantioselectivities. The protocol exhibits wide functional group tolerance, scalability, and downstream synthetic utility, providing access to structurally diverse spirocyclic derivatives. Mechanistic studies reveal that the stereochemical outcome of (N, N)-spiroketal is determined by the atroposelective DyKAT aminocarbonylation step, rather than the subsequent spiroannulation. Moreover, the resulting spiroketal structure has been developed into chiral carbene ligand, as demonstrated by the successful synthesis of its corresponding Rh, Ir, Au and Pd complexes. Chiral (N, N)-spiroketals represent a promising class of scaffolds with potential application in asymmetric catalysis and are frequently encountered in natural products and biologically active compounds, yet their efficient synthesis is still underdeveloped. Herein, the authors report a Pd-catalyzed cascade enantioconvergent aminocarbonylation and intramolecular dearomative nucleophilic aza-addition that enables the efficient synthesis of chiral (N, N)-spiroketal.

Abstract licence: CC BY-NC-ND