AICAR Protects Vascular Endothelial Cells from Oxidative Injury Induced by the Long-Term Palmitate Excess

Hyperlipidemia manifested by high blood levels of free fatty acids (FFA) and lipoprotein triglycerides is critical for the progression of type 2 diabetes (T2D) and its cardiovascular complications via vascular endothelial dysfunction. However, attempts to assess high FFA effects in endothelial culture often result in early cell apoptosis that poorly recapitulates a much slower pace of vascular deterioration in vivo and does not provide for the longer-term studies of endothelial lipotoxicity in vitro. Here, we report that palmitate (PA), a typical FFA, does not impair, by itself, endothelial barrier and insulin signaling in human umbilical vein endothelial cells (HUVEC), but increases NO release, reactive oxygen species (ROS) generation, and protein labeling by malondialdehyde (MDA) hallmarking oxidative stress and increased lipid peroxidation. This PA-induced stress eventually resulted in the loss of cell viability coincident with loss of insulin signaling. Supplementation with 5-aminoimidazole-4-carboxamide-riboside (AICAR) increased endothelial AMP-activated protein kinase (AMPK) activity, supported insulin signaling, and prevented the PA-induced increases in NO, ROS, and MDA, thus allowing to maintain HUVEC viability and barrier, and providing the means to study the long-term effects of high FFA levels in endothelial cultures. An upgraded cell-based model reproduces FFA-induced insulin resistance by demonstrating decreased NO production by vascular endothelium.     

Mechanical properties of single crystals of transition metals diborides TMB<Subscript>2</Subscript> (TM = Sc,Hf, Zr,Ti). Experiment and theory

The mechanical behaviour of TMB₂ whiskers (TMB₂ = Sc, Hf, Zr, Ti) of 10–20 μm in diameter of the directionally reinforced ceramics LaB₆–TMB₂ was experimentally studied by the nanoindentation. The pop-in (the abrupt elastic–plastic transition in the indenter penetration) caused by the nucleation of dislocations in the previously dislocations-free region under the imprint was observed in all samples under study. For the first time the experimental estimations of the theoretical shear strength of these materials are obtained. Zone structures and types of interatomic bonds for TMB₂ (TM= Sc, Zr, Hf, Ti) are theoretically calculated. The effects of the electronic structures on mechanical properties of diborides of transition metals were analyzed.     

Delamination resistance of GFRP‐epoxy rods with nanoparticle‐ and microparticle‐modified matrix and its correlation with the fracture properties of epoxy nanocomposites

Pultruded glass fiber–reinforced plastic (GFRP) rods are industrially produced for various applications. The mechanical properties of GFRP rods can be tailored, eg, with modified epoxy matrix by adding microsized and nanosized fillers. In this work, we investigated the transferability of the fracture properties of epoxy nanocomposites to GFRP epoxy rods. For this purpose, nanosilica particles, micron‐sized rubber, and micron‐sized calcium carbonate were used as fillers. Firstly, epoxy plates with different combinations of nanosized and micron‐sized fillers were produced and their fracture toughness evaluated. Secondly, using binary and ternary epoxy filler systems as matrices, GFRP rods were produced, and their fracture toughness was determined using a modified testing procedure derived from standard composite double cantilever beam specimens. Lastly, the correlation between fracture properties of epoxy nanocomposites and GFRP rods was analysed. Besides that, the fractographic investigations of both epoxy nanocomposites and GFRP rods were carried out and discussed.     

Low-Temperature Synthesis of Boron Carbide Ceramics

This study has been the first to demonstrate the possibility of producing boron carbide ceramics from coarse (D = 25–150 μm) B₄C powder (which is impossible to sinter by conventional methods) through infiltration with molten silicon and subsequent treatment within the field of the controlled temperature gradient. This produces yields a composite ceramics B₄C–SiC–Si with a hardness of 26 to 35 GPa and a splitting tensile strength of 110 to 170 MPa. The influence of the velocity of movement of the temperature gradient on the structure, phase composition, and properties of the prepared composites has been studied.     

Influence of two-stream relativistic electron beam parameters on the space-charge wave with broad frequency spectrum formation

We developed a cubic non-linear theory describing the dynamics of the multiharmonic spacecharge wave (SCW),with harmonics frequencies smaller than the two-stream instability critical frequency,with different relativistic electron beam (REB) parameters.The self-consistent differential equation system for multiharmonic SCW harmonic amplitudes was elaborated in a cubic non-linear approximation.This system considers plural three-wave parametric resonant interactions between wave harmonics and the two-stream instability effect.Different REB parameters such as the input angle with respect to focusing magnetic field,the average relativistic factor value,difference of partial relativistic factors,and plasma frequency of partial beams were investigated regarding their influence on the frequency spectrum width and multiharmonic SCW saturation levels.We suggested ways in which the multiharmonic SCW frequency spectrum widths could be increased in order to use them in multiharmonic two-stream superheterodyne free-electron lasers,with the main purpose of forming a powerful multiharmonic electromagnetic wave.