Dynamic oxidation mechanism of carbon fiber reinforced SiC matrix composite in high-enthalpy and high-speed plasmas

This work employed an inductively coupled plasma wind tunnel to study the dynamic oxidation mechanisms of carbon fiber reinforced SiC matrix composite (Cf/SiC) in high-enthalpy and high-speed plasmas. The results highlighted a transition of passive/active oxidations of SiC at 800–1600 °C and 1–5 kPa. Specially, the active oxidation led to the corrosion of the SiC coating and interruption of the SiO2 growth. The transition borders of active/passive oxidations were thus defined with respect to oxidation temperature and partial pressure of atomic O in the high-enthalpy and high-speed plasmas. In the transition and passive domains, the SiC dissipation was negligible. By multiple dynamic oxidations of Cf/SiC in the domains, the SiO2 thickness was not monotonously increased due to the competing mechanisms of passive oxidation of SiC and dissipation of SiO2. In addition, the mechanical properties of the SiC coating/matrix and the Cf/SiC were maintained after long-term dynamic oxidations, which suggested an excellent thermal stability of Cf/SiC serving in thermal protection systems (TPSs) of reusable hypersonic vehicles.

Effect of the cross-linker length of thiophene units on photocatalytic hydrogen production of triazine-based conjugated microporous polymers

Conjugated microporous polymers (CMPs) have been investigated in the field of photocatalytic hydrogen production because of their extended π-conjugation, tunable chemical structure and excellent thermal stability.

Reveal the large open-circuit voltage deficit of all-inorganic CsPbIBr2 perovskite solar cells

Due to excellent thermal stability and optoelectronic properties, all-inorganic perovskite is one of the promising candidates to solve the thermal decomposition problem of conventional organic-inorganic hybrid perovskite solar cells (PSCs), but the larger voltage loss (V loss) cannot be ignored, especially CsPbIBr2, which limits the improvement of efficiency. To reduce the V loss, one promising solution is the modification of the energy level alignment between perovskite layer and adjacent charge transport layer (CTL), which can facilitate charge extraction and reduce carrier recombination rate at perovskite/CTL interface. Therefore, the key issues of minimum V loss and high efficiency of CsPbIBr2-based PSCs were studied in terms of the perovskite layer thickness, the effects of band offset of CTL/perovskite layer, the doping concentration of the CTL, and the electrode work function in this study based on device simulations. The open-circuit voltage (V oc) is increased from 1.37 V to 1.52 V by replacing SnO2 with ZnO as electron transport layer (ETL) due to more matching conduction band with CsPbIBr2 layer.

The Layered Encapsulation of Vitamin B2 and β-Carotene in Multilayer Alginate/Chitosan Gel Microspheres: Improving the Bioaccessibility of Vitamin B2 and β-Carotene

This research underlines the potential of alginate multilayered gel microspheres for the layered encapsulation and the simultaneous delivery of vitamin B2 (VB) and β-carotene (BC). Chitosan was used to improve the stability and controlled release ability of alginate-based gel microspheres. It was shown that a clear multilayered structure possessed the characteristics of pH response, and excellent thermal stability. The sodium alginate concentration and the number of layers had notable effects on mechanical properties and particle size of gel microspheres. Fourier-transform infrared spectroscopy and X-ray diffraction analyses further proved that VB and BC were encapsulated within the gel microspheres. Compared with the three-layer VB-loaded gel microspheres, the total release of VB from the three-layer VB and BC-loaded gel decreased from 93.23 to 85.58%. The total release of BC from the three-layer VB and BC-loaded gel increased from 66.11 to 69.24% compared with three-layer BC-loaded gel. The simultaneous encapsulation of VB and BC in multilayered gel microspheres can markedly improve their bioaccessibility and bioavailability. These results showed the multilayer gel microspheres synthesized herein have potential for applications in the layered encapsulation and simultaneous delivery of various bioactive substances to the intestinal tract.

Development, characterization, and in vitro evaluation of adhesive fibrous mat for mucosal propranolol delivery

This research focuses on the synthesis and adhesive properties of mucoadhesive mats, prepared with poly(vinylic alcohol) as a base polymer for the oromucosal release of propranolol (PRO) by the electrospinning technique. The nanofibers mats were evaluated by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry; in vitro drug entrapment efficiency, degradation time, and adhesion studies were performed. SEM images of the electrospun mats show the correct formation of fibers with a variable diameter and porosity. Thermal studies indicate excellent thermal stability of the scaffolds, The fibrous mats loaded with 10% of the drug exhibit the best thermal stability with decomposition after 450°C. In vitro studies indicate a drug content of 88% loaded in the mats. In the cytotoxicity test, loaded mat presents cell proliferations of 97% and 88% for drug concentrations of 10% an 15%, respectively. To conclude, the formed electrospun adhesive mats exhibited excellent thermal stability, adhesive properties, and drug entrapment efficiency, promising features for a successful drug topical release system on mucosal tissue in the oral cavity.

Enhanced Energy Storage Density and Excellent Thermal Stability Under Low Electric Fields of KF-added BNT–ST-AN Relaxor Ferroelectric Ceramics Prepared by the Solid-state Combustion Technique

Homogeneous 0.722(Bi0.5Na0.5TiO3)-0.228(SrTiO3)-0.05(AgNbO3) (BNT-ST-AN) ceramics with various amounts of potassium fluoride (KF) added were prepared by the solid-state combustion technique. The ceramics presented a single perovskite phase with coexisting rhombohedral (R), cubic (C) and orthorhombic (O) phases. The amount of the R phase decreased while the percentage of the C+O phase increased when KF addition increased from 0.0 to 3.0 mol%. The smallest grain size, the highest density and maximum dielectric constant (em) were achieved with a KF addition of 1.5 mol%. Following this design composition of the ceramics, the highest recoverable energy-storage density (Wrec ~1.60 J/cm3) and η above 85.8% at a low electric field (100 kV/cm) were obtained from BNT-ST-AN with KF addition at 1.5 mol% because this composition contained a morphotropic phase boundary (MPB) region and had the smallest grain size, which gave the lowest remnant polarization (Pr) and a large maximum polarization (Pm). Additionally, BNT-ST-AN with KF addition at 0.15 mol% exhibits stability over a wide range of temperatures (25–150°C) at a low electric field (100 kV/cm), which shows great potential in pulse-power system applications.