Thermal depolarization and electromechanical hardening in Zn2+-doped Na1/2Bi1/2TiO3-BaTiO3

Na_1/2Bi_1/2TiO₃-based materials have been earmarked for one of the first large-volume applications of lead-free piezoceramics in high-power ultrasonics. Zn²⁺-doping is demonstrated as a viable route to enhance the thermal depolarization temperature and electromechanically harden (1-y)Na_1/2Bi_1/2TiO₃-yBaTiO₃ (NBT100yBT) with a maximum achievable operating temperature of 150 °C and mechanical quality factor of 627 for 1 mole % Zn²⁺-doped NBT6BT. Although quenching from sintering temperatures has been recently touted to enhance T_F-R, with quenching the doped compositions featuring an additional increase in T_F-R by 17 °C, it exhibits negligible effect on the electromechanical properties. The effect is rationalized considering the missing influence on conductivity and therefore, negligible changes in the defect chemistry upon quenching. High-resolution diffraction indicates that Zn²⁺-doped samples favor the tetragonal phase with enhanced lattice distortion, further corroborated by ²³Na Nuclear Magnetic Resonance investigations.     

Nanolayer CrAlN/TiSiN coating designed for tribological applications

With the goal to produce a hard and tough coating intended for tribological applications, CrAlN/TiSiN nanolayer coating was prepared by alternative deposition of CrAlN and TiSiN layers. In the first part of the article, a detailed study of phase composition, microstructure, and layer structure of CrAlN/TiSiN coating is presented. In the second part, its mechanical properties, fracture and tribological behavior are compared to the nanocomposite TiSiN coating. An industrial magnetron sputtering unit was used for coating deposition. X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used for compositional and microstructural analysis. Mechanical properties and fracture behavior were studied by instrumented indentation and focused ion beam techniques. Tribological properties were evaluated by ball-on-disk test in a linear reciprocal mode. A complex layer structure was found in the nanolayer coating. The TiSiN layers were epitaxially stabilized inside the coating which led to formation of dislocations at interfaces, to introduction of disturbances in the coating growth, and as a result, to development of fine-grained columnar microstructure. Indentation load required for the onset of fracture was twice lower for the nanolayer CrAlN/TiSiN, compared to the nanocomposite TiSiN coating. This agrees very well with their mechanical properties, with H³/E² being twice higher for the TiSiN coating. However, the nanolayer coating experienced less severe damage, which had a strong impact on tribological behavior. A magnitude of order lower wear rate and four times lower steady state friction coefficient were found for the nanolayer coating.     

State-of-the-art technology: Recent investigations on laser-mediated synthesis of nanocomposites for environmental remediation

In both developing and industrialized/developed countries, various hazardous/toxic environmental pollutants are entering water bodies from organic and inorganic compounds (heavy metals and specifically dyes). The global population is growing whereas the accessibility of clean, potable and safe drinking water is decreasing, leading to world deterioration in human health and limitation of agricultural and/or economic development. Treatment of water/wastewater (mainly industrial water) via catalytic reduction/degradation of environmental pollutants is extremely critical and is a major concern/issue for public health. Light and/or laser ablation induced photocatalytic processes have attracted much attention during recent years for water treatment due to their good (photo)catalytic efficiencies in the reduction/degradation of organic/inorganic pollutants. Pulsed laser ablation (PLA) is a rather novel catalyst fabrication approach for the generation of nanostructures with special morphologies (nanoparticles (NPs), nanocrystals, nanocomposites, nanowires, etc.) and different compositions (metals, alloys, oxides, core-shell, etc.). Laser ablation in liquid (LAL) is generally considered a quickly growing approach for the synthesis and modification of nanomaterials for practical applications in diverse fields. LAL-synthesized nanomaterials have been identified as attractive nanocatalysts or valuable photocatalysts in (photo)catalytic reduction/degradation reactions. In this review, the laser ablation/irradiation strategies based on LAL are systematically described and the applications of LAL synthesized metal/metal oxide nanocatalysts with highly controlled nanostructures in the degradation/reduction of organic/inorganic water pollutants are highlighted along with their degradation/reduction mechanisms.     

The Interfacial Interactions of Glycine and Short Glycine Peptides in Model Membrane Systems

The interactions of amino acids and peptides at model membrane interfaces have considerable implications for biological functions, with the ability to act as chemical messengers, hormones, neurotransmitters, and even as antibiotics and anticancer agents. In this study, glycine and the short glycine peptides diglycine, triglycine, and tetraglycine are studied with regards to their interactions at the model membrane interface of Aerosol-OT (AOT) reverse micelles via ¹H NMR spectroscopy, dynamic light scattering (DLS), and Langmuir trough measurements. It was found that with the exception of monomeric glycine, the peptides prefer to associate between the interface and bulk water pool of the reverse micelle. Monomeric glycine, however, resides with the N-terminus in the ordered interstitial water (stern layer) and the C-terminus located in the bulk water pool of the reverse micelle.     

High Levels of the Cleaved Form of Galectin-9 and Osteopontin in the Plasma Are Associated with Inflammatory Markers That Reflect the Severity of COVID-19 Pneumonia

Numbers of patients with coronavirus disease 2019 (COVID-19) have increased rapidly worldwide. Plasma levels of full-length galectin-9 (FL-Gal9) and osteopontin (FL-OPN) as well as their truncated forms (Tr-Gal9, Ud-OPN, respectively), are representative inflammatory biomarkers. Here, we measured FL-Gal9, FL-OPN, Tr-Gal9, and Ud-OPN in 94 plasma samples obtained from 23 COVID-19-infected patients with mild clinical symptoms (CV), 25 COVID-19 patients associated with pneumonia (CP), and 14 patients with bacterial infection (ID). The four proteins were significantly elevated in the CP group when compared with healthy individuals. ROC analysis between the CV and CP groups showed that C-reactive protein had the highest ability to differentiate, followed by Tr-Gal9 and ferritin. Spearman’s correlation analysis showed that Tr-Gal9 and Ud-OPN but not FL-Gal9 and FL-OPN, had a significant association with laboratory markers for lung function, inflammation, coagulopathy, and kidney function in CP patients. CP patients treated with tocilizumab had reduced levels of FL-Gal9, Tr-Gal9, and Ud-OPN. It was suggested that OPN is cleaved by interleukin-6-dependent proteases. These findings suggest that the cleaved forms of OPN and galectin-9 can be used to monitor the severity of pathological inflammation and the therapeutic effects of tocilizumab in CP patients.     

Effects of Cu on the corrosion behavior and microstructure of Mg–Zn–Ca bulk metallic glass

For the purpose of developing biodegradable magnesium alloys with suitable properties for biomedical applications, Mg–Zn–Ca–Cu metallic glasses were prepared by copper mold injection methods. In the present work, the effect of Cu doping on mechanical properties, corrosion behavior, and glass-forming ability of Mg₆₆Zn₃₀Ca₄ alloy was studied. The experimental findings demonstrated that the incorporation of Cu decreases the corrosion resistance of alloys, but increases the microhardness and degradation rate slightly. However, the addition of a trace amount of Cu can make the samples have antibacterial properties. Therefore, Mg–Zn–Ca–Cu has great advantages in clinical implantation and is the potential implant material.     

Phase,domain, and microstructures in Sr2+ substituted low-temperature sintering PZT-based relaxor ferroelectrics

The Ag-Pd internal electrode of multilayer piezoelectric ceramics needs to be sintered below 1000°C, and lead wires and components need to be welded with lead-free solder at 260°C. PNN–PMW–PZT–xSr piezoelectric ceramics with high Curie temperature (T_c > 260°C) were synthesized at a low sintering temperature (960°C) to meet the requirements of multilayer piezoelectric devices. The relationship between structures (phase, domain, and microstructures) and electrical properties (piezo/ferroelectric properties, and dielectric relaxation) in the Sr²⁺ substituted ceramics was investigated. Rietveld refinement and Raman spectra show that Sr²⁺ substitution can cause the phase change and increase the force constant of [BO₆] octahedron. The piezoelectric response increases with increasing the content of the tetragonal phase (CTP) in the rhombohedral-tetragonal (R-T) coexisted ceramics. The ceramics with 0.6 mol% Sr²⁺ substitution have minimum activation energy for domain wall movement (E_a) of 0.0362 eV which favors the formation of nanometer-sized domains, and possess excellent electrical properties (d₃₃ = 623 pC/N, d₃₃^* =783 pm/V, T_c =295°C). The higher the CTP, the lower the E_a. The lower E_a favors the rotation of polarization direction and extension, and is beneficial to the generation of the nanometer-size domains, resulting in high piezoelectric properties.     

Stress field and damage evolution in C/SiC woven composites: Image-based finite element analysis and in situ X-ray computed tomography tests

The construction and examination of meso-structural finite element models of a Chemical-Vapor-Infiltrated (CVI) C/SiC composite is carried out based on X-ray microtomography digital images (IB-FEM). The accurate meso-structural features of the C/SiC composites, which are consisted of carbon fiber tows and CVI-SiC matrix, in particular the cavity defects, are reconstructed. With the IB-FEM, the damage evolution and fracture behaviors of the C/SiC composite are investigated. At the same time, an in situ tensile test is applied to the C/SiC composite under a CT real-time quantitative imaging system, aiming to investigate the damage and failure features of the material as well as to verify the IB-FEM. The IB-FEM results indicate that material damage initially occur at the defects, followed by propagating toward the fiber-tow/SiC-matrix interfaces, ultimately, combined into macro-cracks, which is in good agreement with the in situ CT experiment results.     

Targeted editing of intronic-splicing silencer enhancement of SMN2 Exon 7 inclusion by CRISPR/Case 9

Spinal muscular atrophy (SMA) is an autosomal recessive hereditary neuromuscular disease. Exon 7 and 8 of survival of motor neuron 1 (SMN1) gene or only exon 7 homology deletion leads to the failure to produce a full-length SMN gene. The copy number of SMN2 gene with high homology of SMN1 affects the degree of disease and was the target gene for targeting therapy, in which splicing silencer in intron 7 was the key to suppress the inclusion of exon 7. In this study, we projected to use CRISPR/Case 9 for the targeted editing of intronic-splicing silencer (ISS) sequence to promote the inclusion of SMN2 exon 7 and increase the production of SMN2 full-length (FL) gene expression. It happens that there was a protospacer adjacent motif (PAM) at one end of the ISS sequence according to the design of sgRNA. The recombinant vector of sgRNA HSMN2 CRISPR/Case 9 was constructed and transfected into HEK293 cells. Sequencing results showed that the ISS sequence could be edited accurately and targeting in the predicted direction, in which deleting small fragments, inserting small amounts and mutation. Quantitative analysis of RT-PCR products by restriction enzyme of DdeI digestion showed that the FL of SMN2 increased by 8% (P < 0.05). In the primary cultured chondrocytes of SMA mice, in which sgRNA HSMN2 CRISPR/Case9 recombinant vector transfection could increase the SMN2 FL gene by 23% (P < 0.05) and significantly improve SMN protein levels (P < 0.05). CRISPR/Case 9 is an effective tool for gene editing and therapy of hereditary diseases, but it is rarely reported in the treatment of SMA diseases. This study shows that CRISPR/Case 9 was first used for the precision target of ISS sequence editing, which can effectively promote the production of SMN2 FL gene expressions, in which there was an important clinical reference value.