Microwave assisted combustion synthesis in the system Ti–Si–C for the joining of SiC: Experimental and numerical simulation results

Microwaves at 2.45 GHz have been applied to ignite the combustion synthesis of compacted Ti–Si–C powders mixtures, having 1:1:1 atomic ratio, in order to join SiC-based components. A mixture of different refractory phases such as TiC and TiSi₂ were obtained. Depending on the synthesis conditions, no residual silicon in the joint was detected, suggesting the suitability of the here proposed experimental joining approach for nuclear plants and high temperature applications. A simplified model was developed with the aim of obtaining a deeper understanding of the here proposed rapid, almost pressure-less and localized heating joining method. Experimental and numerical simulation results demonstrate that joining of SiC can be rapidly obtained with minimization of heat affected zones in the SiC substrates. Maximum apparent shear strength values of the joints ranged from 9.9 to 45.1 MPa, depending on the process conditions.     

Nucleation behavior of blended high‐melting fractions of milk fat as affected by emulsifiers

The effect of highly hydrophobic emulsifiers, the palmitic sucrose ester P‐170 (hydrophilic/lipophilic balance (HLB) = 1.0), the stearic sucrose ester S‐170 (HLB = 1.0), the polyglycerol ester decaglycerol decastearate DAS 7S (HLB = 3.7) and the polyglycerol ester decaglycerol dodecabehenate DDB 750 (HLB = 2.6), on the nucleation of a high melting point milk fat fraction (HMF) and its blends with sunflower oil (SFO) was investigated by polarized laser light turbidimetry, X‐ray diffractometry and polarized light microscopy (PLM). Addition of polyglycerol esters accelerated nucleation, giving shorter induction times for the same supercooling. On the contrary, sucrose esters inhibited nucleation since induction times were elongated in all conditions selected. Addition of emulsifiers modified the polymorphic behavior in the blends with SFO. The β' form was promoted especially with the addition of S‐170. DAS 7S and DDB 750 promoted crystallization. PLM images showed many small crystals that did not appear in HMF images. Addition of P‐170 and S‐170 delayed nucleation and inhibited crystal growth. Crystals were notoriously smaller than the ones that appeared in HMF images. The Fisher–Turnbull model was used to calculate activation free energies of nucleation. In all cases, sucrose esters elevated the energy barrier for nucleation. Polyglycerol esters, however, if they had an effect on the energy barrier, lowered the values.     

Adipose Stromal/Stem Cell-Derived Extracellular Vesicles: Potential Next-Generation Anti-Obesity Agents

Over the last decade, several compounds have been identified for the treatment of obesity. However, due to the complexity of the disease, many pharmacological interventions have raised concerns about their efficacy and safety. Therefore, it is important to discover new factors involved in the induction/progression of obesity. Adipose stromal/stem cells (ASCs), which are mostly isolated from subcutaneous adipose tissue, are the primary cells contributing to the expansion of fat mass. Like other cells, ASCs release nanoparticles known as extracellular vesicles (EVs), which are being actively studied for their potential applications in a variety of diseases. Here, we focused on the importance of the contribution of ASC-derived EVs in the regulation of metabolic processes. In addition, we outlined the advantages/disadvantages of the use of EVs as potential next-generation anti-obesity agents.     

CD8+ T Cell Senescence: Lights and Shadows in Viral Infections,Autoimmune Disorders and Cancer

CD8⁺ T lymphocytes are a heterogeneous class of cells that play a crucial role in the adaptive immune response against pathogens and cancer. During their lifetime, they acquire cytotoxic functions to ensure the clearance of infected or transformed cells and, in addition, they turn into memory lymphocytes, thus providing a long-term protection. During ageing, the thymic involution causes a reduction of circulating T cells and an enrichment of memory cells, partially explaining the lowering of the response towards novel antigens with implications in vaccine efficacy. Moreover, the persistent stimulation by several antigens throughout life favors the switching of CD8⁺ T cells towards a senescent phenotype contributing to a low-grade inflammation that is a major component of several ageing-related diseases. In genetically predisposed young people, an immunological stress caused by viral infections (e.g., HIV, CMV, SARS-CoV-2), autoimmune disorders or tumor microenvironment (TME) could mimic the ageing status with the consequent acceleration of T cell senescence. This, in turn, exacerbates the inflamed conditions with dramatic effects on the clinical progression of the disease. A better characterization of the phenotype as well as the functions of senescent CD8⁺ T cells can be pivotal to prevent age-related diseases, to improve vaccine strategies and, possibly, immunotherapies in autoimmune diseases and cancer.     

Gelcasting of dense and porous ceramics by using a natural gelatine

An improved gel-casting procedure was successfully exploited to produce porous ceramic bodies having controlled porosity features in terms of mean pore size, total pore volume as well as pore geometry. The gel-casting process in which a natural gelatine for food industry is used as gelling agent was firstly set-up to prepare dense alumina and zirconia components. Then, commercial PE spheres, sieved to select proper dimensional ranges, were added to the starting slurries as pore-forming agent. Both alumina and zirconia porous bodies were then produced, having a porosity ranging between 40 and 50 vol%. The fired components were characterised by spherical pores surrounded by highly dense ceramic walls and struts, having a homogeneous and fine microstructure. Their mean pore size was directly dependent on the sieved fraction of the starting PE spheres selected as pore-forming phase.     

Direct <Emphasis Type="SmallCaps">d</Emphasis>-Glucose Oxidation over Noble Metal Nanoparticles Introduced on Polymer and Inorganic Supports

In the present work, nanocatalysts prepared on inorganic supports (zeolites) were investigated in d-glucose oxidation and compared to systems supported on polymer (hypercrosslinked polystyrene (HPS)) previously described. Catalytic activities and selectivities were measured under various reaction conditions. The selectivity of d-glucose oxidation and activity of both Pd-containing zeolites and HPS-Ru were similar (99.7% and TOF 0.013–0.014 mol/(mol Me s)). Physicochemical analysis X-ray photoelectron spectroscopy, liquid nitrogen physisorption, diffuse reflectance infrared Fourier transform spectroscopy of adsorbed CO for metal sites evaluation, CD₃CN for acid sites evaluation showed that Pd species were in oxidic form, while Ru species were in oxidic and reduced form. The catalytic activity decreased when acidic sites were present in Pd-containing zeolites.     

Endothelial Glycocalyx as a Regulator of Fibrotic Processes

The endothelial glycocalyx, the gel layer covering the endothelium, is composed of glycosaminoglycans, proteoglycans, and adsorbed plasma proteins. This structure modulates vessels’ mechanotransduction, vascular permeability, and leukocyte adhesion. Thus, it regulates several physiological and pathological events. In the present review, we described the mechanisms that disturb glycocalyx stability such as reactive oxygen species, matrix metalloproteinases, and heparanase. We then focused our attention on the role of glycocalyx degradation in the induction of profibrotic events and on the possible pharmacological strategies to preserve this delicate structure.     

IgGs-Abzymes from the Sera of Patients with Multiple Sclerosis Recognize and Hydrolyze miRNAs

Autoantibodies-abzymes hydrolyzing DNA, myelin basic protein, and oligosaccharides have been revealed in the sera of patients with multiple sclerosis (MS). In MS, specific microRNAs are found in blood and cerebrospinal fluid, which are characterized by increased expression. Autoantibodies, specifically hydrolyzing four different miRNAs, were first detected in the blood of schizophrenia patients. Here, we present the first evidence that 23 IgG antibodies of MS patients effectively recognize and hydrolyze four neuroregulatory miRNAs (miR-137, miR-9-5p, miR-219-2-3p, and miR-219-5p) and four immunoregulatory miRNAs (miR-21-3p, miR-146a-3p, miR-155-5p, and miR-326). Several known criteria were checked to show that the recognition and hydrolysis of miRNAs is an intrinsic property of MS IgGs. The hydrolysis of all miRNAs is mostly site-specific. The major and moderate sites of the hydrolysis of each miRNA for most of the IgG preparations coincided; however, some of them showed other specific sites of splitting. Several individual IgGs hydrolyzed some miRNAs almost nonspecifically at nearly all internucleoside bonds or demonstrated a combination of site-specific and nonspecific splitting. Maximum average relative activity (RA) was observed in the hydrolysis of miR-155-5p for IgGs of patients of two types of MS—clinically isolated syndrome and relapsing-remitting MS—but was also high for patients with primary progressive and secondary progressive MS. Differences between RAs of IgGs of four groups of MS patients and healthy donors were statistically significant (p < 0.015). There was a tendency of decreasing efficiency of hydrolysis of all eight miRNAs during remission compared with the exacerbation of the disease.