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Pleural mesothelioma (PM) is a highly aggressive tumor that is caused by asbestos exposure and lacks effective therapeutic regimens. Current procedures for PM diagnosis are invasive and can take a long time to reach a definitive result. Small extracellular vesicles (sEVs) have been identified as important communicators between tumor cells and their microenvironment via their cargo including circular RNAs (circRNAs). CircRNAs are thermodynamically stable, highly conserved, and have been found to be dysregulated in cancer. This study aimed to identify potential biomarkers for PM diagnosis by investigating the expression of specific circRNA gene pattern (hsa_circ_0007386) in cells and sEVs using digital polymerase chain reaction (dPCR). For this reason, 5 PM, 14 non-PM, and one normal mesothelial cell line were cultured. The sEV was isolated from the cells using the gold standard ultracentrifuge method. The RNA was extracted from both cells and sEVs, cDNA was synthesized, and dPCR was run. Results showed that hsa_circ_0007386 was significantly overexpressed in PM cell lines and sEVs compared to non-PM and normal mesothelial cell lines (p < 0.0001). The upregulation of hsa_circ_0007386 in PM highlights its potential as a diagnostic biomarker. This study underscores the importance and potential of circRNAs and sEVs as cancer diagnostic tools.

Previous studies have been shown that high strength A1-Zn-Mg based alloys suffer environment assisted cracking. In the present work, room temperature constant strain rate (.0001/s - .000001/s) and constant load tensile tests on A1 6% Zn 3% Mg and copper and chromium containing variants were extended to specimens pre-exposed to a steam environment at 120 C and to specimens tested in air, distilled water and salt solution. The embrittlement increased at lower strain rates, higher water content, and in the presence of chloride ions. In all cases, atomic hydrogen absorbed into the grain boundaries and the grain matrix causes grain boundary decohesion and cleavage. The ability to trap atomic hydrogen as H2 bubbles improves the embrittlement resistance. It is believed that the addition of copper to the alloy increases the hydrogen trapping efficiency, hence embrittlement resistance whereas in the chromium containing alloy, the oxide is probably modified to inhibit hydrogen entry. Originator supplied keywords include: Aqueous environments, cleavage, constant strain rate test, corrosion wedging effect, crack arrest, crack branching, dead load test, discontinuous crack growth (microscopic and macroscopic), dissolution, ductility ratio, grain hydrogen embrittlement, hydrogen permeation, life time ratio, pre-exposure steam environment.

Three alloys, Al 6% Zn 3% Mg. Al 6% Zn 3% Mg 1.7% Cu and Al 6% Zn 3% Mg 0.14% Cr. were pre-exposed in the solution treated condition to water vapour at 115C. Dry control tests were also performed. Both sets of samples were tested in tension using a slow strain rate of 1/1,000,000S and the results were compared with previously obtained data using a strain rate of 1/1000S. All the samples exposed to steam showed evidence of hydrogen embrittlement, the effects being more severe at the slow strain rate. Evidence was also obtained for hydrogen embrittlement via reaction of the metal with the laboratory air during slow strain rate testing in all cases except for the copper containing alloy. Both intergranular and transgranular brittle fracture can be produced as a result of hydrogen absorption into the metal: tolerance to hydrogen is related to the ability of the microstructure to trap hydrogen in the form of gas bubbles.

Two alloys, A1 6% Zn 3% Mg 1.7% Cu and A1 6% Zn 3% Mg 0.14% Cr artificially aged at 120 C for times up to 400 hours have been tested at room temperature in tension in two aqueous environments, distilled water and 3.5% sodium chloride solution at strain rates of 10 to the minus 4th power/second, 10 to the minus 5th power/second, and 10 to the minus 6th power/second. The results have been compared with previous data on fast and slow strain rate pre-exposure tests. Also conventional dead load tests were carried out in laboratory air and distilled water using the copper containing alloy. Both the slow strain rate technique and the dead load test are closely related and the observations are consistent with the hydrogen model for embrittlement via reaction of the metal with the testing environment during straining or loading. The hydrogen adsorbed into the grain boundaries and the grain matrix causes grain boundary decohesion and cleavage. The ability to trap this hydrogen as innocuous hydrogen bubbles improves the embrittlement resistance. A peak embrittlement resistance is found to be around 150-250 hours of ageing at 120 C for the copper quaternary alloy. The embrittlement resistance mechanism and kinetics are not fully understood and may be complicated by the dissolution processes which accompany hydrogen generation. In this context the observation of grain boundary oxide films on the fracture surfaces of a small number of the dead load samples may be of importance.