Characterizing the Spatiotemporal Transcriptomic Response of the Right Ventricle to Acute Pressure Overload.

This study analyzed microarray data of right ventricular (RV) tissue from rats exposed to pulmonary embolism to understand the initial dynamic transcriptional response to mechanical stress and compare it with experimental pulmonary hypertension (PH) models. The dataset included samples harvested from 55 rats at 11 different time points or RV locations. We performed principal component analysis (PCA) to explore clusters based on spatiotemporal gene expression. Relevant pathways were identified from fast gene set enrichment analysis using PCA coefficients. The RV transcriptomic signature was measured over several time points, ranging from hours to weeks after an acute increase in mechanical stress, and was found to be highly dependent on the severity of the initial insult. Pathways enriched in the RV outflow tracts of rats at 6 weeks after severe PE share many commonalities with experimental PH models, but the transcriptomic signature at the RV apex resembles control tissue. The severity of the initial pressure overload determines the trajectory of the transcriptomic response independent of the final afterload, but this depends on the location where the tissue is biopsied. Chronic RV pressure overload due to PH appears to progress toward similar transcriptomic endpoints.

Dynamic Heterogeneities in Liquid Mixtures Confined in Nanopores.

Binary liquid mixtures can exhibit nanosegregation, albeit being fully miscible and homogeneous at the macroscopic scale. This tendency can be amplified by geometrical nanoconfinement, leading to remarkable properties. This work investigates the molecular dynamics of tert-butanol (TBA)-toluene (TOL) mixtures confined in silica nanochannels by quasielastic neutron scattering and molecular dynamics simulation. It reveals a decoupling of the molecular motion of each constituent of the binary liquid, which can be followed independently by selective isotopic H/D labeling. We argue that this behavior is the signature of spatially segregated dynamic heterogeneities, which are due to the recently established core-shell nanophase separation induced by mesoporous confinement.

Free Energy of Nucleation and Interplay between Size and Composition in CuNi Systems.

Using molecular simulation, we shed light on the crystal nucleation process in systems of Cu, Ni, and their nanoalloy. For each system, we simulate the formation of the crystal nucleus along the entire nucleation pathway and determine the free energy barrier overcome by the system to form a critical nucleus. Comparing the results obtained for the pure metals to those for the nanoalloy, we analyze the impact of alloying on the free energy of nucleation, as well as on the size and structure of the crystal nucleus. Specifically, we relate the greater free energy of nucleation, and bigger critical nuclei, obtained for the nanoalloy, to the difference in size and cohesive energy between the two metals. Furthermore, we characterize the dependence of the local composition of the incipient crystal cluster on its size, which is of key significance for the applications of bimetallic nanoparticles in catalysis.