Examining the thermal properties of unirradiated nuclear grade graphite between 750 and 2500 K

This study presents the first high temperature measurements (between 750 K and 2500 K) of thermal conductivity, thermal diffusivity, specific heat and spectral emissivity of virgin graphite samples (type IM1-24) from advanced gas-cooled reactor (AGR) fuel assembly bricks. Scanning electron microscope (SEM) and X-ray computed tomography (XRT) techniques were used to verify the presence of Gilsocarbon filler particles (a characteristic microstructural feature of IM1-24 graphite). All thermal properties were investigated in two orthogonal directions, which showed the effective macroscopic thermal conductivity to be the same (to within experimental error). This can be linked to the morphology of the filler particles that consist of concentrically aligned graphitic platelets. The resulting spherical symmetry allows for heat to flow in the same manner in both macroscopic directions. The current thermal conductivity results were compared to other isotropic grade graphite materials. The significant discrepancies between the thermal conductivities of the individual grades are likely the result of different manufacturing processes yielding variations in the microstructure of the final product. Differences were identified in the filler particle size and structure, and possibly the degree of graphitization compared to other reported nuclear graphites

Intrinsic MYH7 expression regulation contributes to tissue level allelic imbalance in hypertrophic cardiomyopathy

HCM, the most common inherited cardiac disease, is mainly caused by mutations in sarcomeric genes. More than a third of the patients are heterozygous for mutations in the MYH7 gene encoding for the β-myosin heavy chain. In HCM-patients, expression of the mutant and the wildtype allele can be unequal, thus leading to fractions of mutant and wildtype mRNA and protein which deviate from 1:1. This so-called allelic imbalance was detected in whole tissue samples but also in individual cells. There is evidence that the severity of HCM not only depends on the functional effect of the mutation itself, but also on the fraction of mutant protein in the myocardial tissue. Allelic imbalance has been shown to occur in a broad range of genes. Therefore, we aimed to examine whether the MYH7-alleles are intrinsically expressed imbalanced or whether the allelic imbalance is solely associated with the disease. We compared the expression of MYH7-alleles in non-HCM donors and in HCM-patients with different MYH7-missense mutations. In the HCM-patients, we identified imbalanced as well as equal expression of both alleles. Also at the protein level, allelic imbalance was determined. Most interestingly, we also discovered allelic imbalance and balance in non-HCM donors. Our findings therefore strongly indicate that apart from mutation-specific mechanisms, also non-HCM associated allelic-mRNA expression regulation may account for the allelic imbalance of the MYH7 gene in HCM-patients. Since the relative amount of mutant mRNA and protein or the extent of allelic imbalance has been associated with the severity of HCM, individual analysis of the MYH7-allelic expression may provide valuable information for the prognosis of each patient