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The development of vaccines has always been an essential task worldwide since vaccines are regarded as powerful weapons in protecting the global population. Although the vast majority of currently authorized human vaccinations are administered intramuscularly or subcutaneously, exploring novel routes of immunization has been a prominent area of study in recent years. This is particularly relevant in the face of pandemic diseases, such as COVID-19, where respiratory immunization offers distinct advantages, such as inducing systemic and mucosal responses to prevent viral infections in both the upper and lower respiratory tracts and also leading to higher patient compliance. However, the development of respiratory vaccines confronts challenges due to the physiological barriers of the respiratory tract, with most of these vaccines still in the research and development stage. In this review, we detail the structure of the respiratory tract and the mechanisms of mucosal immunity, as well as the obstacles to respiratory vaccination. We also examine the considerations necessary in constructing a COVID-19 respiratory vaccine, including the dosage form of the vaccines, potential excipients and mucosal adjuvants, and delivery systems and devices for respiratory vaccines. Finally, we present a comprehensive overview of the COVID-19 respiratory vaccines currently under clinical investigation. We hope this review can provide valuable insights and inspiration for the future development of respiratory vaccinations. [Display omitted] [ABSTRACT FROM AUTHOR]

Nanoscale [(Ba 0.85 Ca 0.15) 0.995 Nd 0.005 ](Ti 0.9 Hf 0.1)O 3 (Nd-BCTH) ceramics were prepared via the hydrothermal method, and the effects of sintering temperature and holding time on the phase structure, micromorphology, electrical and optical properties of the Nd-BCTH ceramics were explored. All the Nd-BCTH ceramics present rather pure perovskite structure with composition approaching rhombohedral phase around the morphotropic phase boundary (MPB) region. The highest relative density is obtained for the sample sintered at 1220 °C for 10 h. The existence of Ba2+, Ca2+, Ti4+, Hf4+ and Nd3+ is confirmed and the elements distribute rather uniformly detected by X-ray photoelectron spectrometer (XPS) and energy dispersive X-ray (EDX) analysis. The ceramics present nanoscale grain size, which tends to increase with the increase of sintering temperature and holding time, and significantly affects dielectric constant and Curie temperature. Very thin and narrow ferroelectric hysteresis loops are observed, where a considerable energy storage density (173.88 mJ/cm3) and high energy storage efficiency (80.68%) are obtained at low electric field. The increase of sintering temperature and holding time induces a red shift at 400 nm absorption edge and a blue shift at 300 nm absorption edge in the Nd-BCTH ceramics, and all ceramics have a maximum absorption value at around 260 nm. Under the excitation of 269 nm light, the Nd-BCTH ceramics show the strongest fluorescence peak at 473 nm, corresponding to the 4G 3/2 →4I 9/2 transition, emitting indigo blue fluorescence. When the ambient temperature is above 400 °C, grains conduction dominates the conductive mechanism in the nano-sized Nd-BCTH ceramics. Such conduction can be attributed to oxygen vacancies caused due to the evaporation of alkaline-earth metals during high temperature sintering, and show typically thermally excited relaxation process. • Pure perovskite structure Nd-BCTH ceramics are prepared via the hydrothermal method. • The Nd-BCTH ceramics present a dense microstructure and all elements distribute evenly. • The dielectric constant and Curie temperature decrease, and piezoelectric properties lose due to the nanometer grain size. • The ceramics have very thin and long hysteresis loops, and present excellent low electric field energy storage performance. • Via Nd doping, the ceramics present strong fluorescent performance and realize multi-functionality. [ABSTRACT FROM AUTHOR]

• Well dispersed Nd-BCTH nanopowders were prepared by hydrothermal method without adding surfactant. • Optimized hydrothermal synthesis conditions for preparing Nd-BCTH nanopowders were obtained by orthogonal experiment designing. • Under optimized hydrothermal conditions, the Nd-BCTH nanopowders present pure pseudo-cubic perovskite structure in nano-sized particles. • Via Nd doping, strong fluorescent performance is induced in the BCTH system, which is beneficial for realizing multi-functionality. Synthesis conditions for preparing [(Ba 0.85 Ca 0.15) 0.995 Nd 0.005 ](Ti 0.9 Hf 0.1)O 3 (Nd-BCTH) nanopowders by hydrothermal method were tailored using orthogonal experiment method with three factors and three levels. X-ray diffraction measurement, field emission scanning electron microscopy, transmission electron microscopy, surface aperture adsorption analyzer, ultraviolet–visible spectra, and fluorescence spectrophotometer were used to characterized the synthesized nanopowders. Well dispersed Nd-BCTH nanopowders with excellent crystallization and luminescence properties are obtained at reaction temperature of 200 °C, 14 mol⋅L−1 alkali concentration, and 24 h reaction time without adding surfactant. The nanopowders present a pure pseudo-cubic perovskite structure with rhombohedral phase approaching the morphotropic phase boundary (MPB) at room temperature, which present nano-sized particles with slight conglomeration. Using 267 nm light exciting, strong photoluminescent emission peaks are excited at 364 nm, 422 nm and 440 nm in the Nd-BCTH nanopowders, which correlate with the transitions of Nd3+ from 4D 3/2 → 4I 9/2 , 2D 5/2 → 4I 9/2 and 4G 11/2 → 4I 9/2 via two processes of non-radiative relaxation and fluorescent transition, respectively. The CIE1931 chromaticity calculation of the emission peaks and fluorescent photograph show that the Nd-BCTH nanopowders emit indigo blue fluorescent light. [ABSTRACT FROM AUTHOR]

• The hysteresis degree of DSP is decreased after encapsulation. • The reason for the hysteresis is the difference in the molecular structure during the heating and cooling process. • The system energy of encapsulated DSP is mainly decided by "randomly distributed" molecules. • Molecular dynamics simulation of pure DSP and encapsulated DSP. There is a phenomenon of inconsistent melting and solidification behavior of PCM, which is called phase change hysteresis, generally expressed by the difference between melting temperature (T m) and solidification temperature (T s). The hysteresis degree (T m -T s) is proportional to the energy loss of the system, if the temperature is beyond the operating temperature range of the system, the latent heat of the PCM cannot be exploited. The phase change hysteresis and supercooling were regarded as the same concept in previous studies no matter simulations or experimental research, which will lead to large errors. It is believed that there is a large hysteresis degree of inorganic PCM besides higher supercooling degree, poor chemical stability, and serious phase separation phenomenon, like Na 2 HPO 4 ·12H 2 O(DSP), which is prone to dehydrate from Na 2 HPO 4 ·12H 2 O to Na 2 HPO 4 ·7H 2 O during the heating and cooling process.DSP is adsorbed by SiO 2 via hydrogen bond, van der Waals force, and capillary effect, which can solve the above shortcomings. There are certain limitations in studying the hysteresis properties of PCM via experimental methods. As so far, the hysteresis properties of inorganic hydrated salts are rarely discussed in related papers, the reason for the hysteresis phenomenon is not explained, and the nucleation mechanism is not clear. Therefore, a composite phase change material (CPCM) model with DSP as the core and mesoporous silica MCM-41 as the shell was established in this work. The phase change hysteresis (PCH) characteristics are studied by analyzing the radial distribution function (RDF), self-diffusion coefficient(D), and density. The molecular motion of the interface layer was studied by the molecular dynamics(MD) method, and the arrangement of microscopic particles before and after adsorption was compared. The results showed that the hysteresis degree of DSP decreases to 1.5 °C after encapsulation by SiO 2 , which is because the effect of "Near-range ordered" molecules tend to disappear. After experimental verification, there is a 20% error between the simulation and experimental results. In addition, the reason for the hysteresis is the difference in the molecular structure that determines the energy of the system during the heating and cooling process. The purpose of this paper is to explain the reasons for the hysteresis from the view of microscopic and to provide a basis for the design of LHTES systems. [ABSTRACT FROM AUTHOR]

The CRISPR/Cas9 genome editing tool has been extensively utilized in filamentous fungi, including Trichoderma reesei. However, most existing systems employ constitutive promoters for the expression of Cas9 protein within the cells or directly introduce Cas9 protein into the cells, which often leads to continuous expression of Cas9 resulting in undesired phenotypes or increased operational cost. In this study, we identified a q uinic a cid (QA)- i nduced qai5 promoter and employed it to express Cas9, thereby establishing an inducible genome editing system in T. reesei. By utilizing this system, we successfully edited the ypr1 gene and the silent gene cluster involved in ilicicolin H synthesis using donor DNA labeling 41-bp homology arm (HA), resulting in an editing efficiency ranging from 29.2 % to 46.7 %. Consequently, biosynthesis of ilicicolin H was achieved in T. reesei. To summarize, this study presents a novel form of CRISPR/Cas9 genome editing system that enables efficient and controllable genetic modifications in T. reesei. [ABSTRACT FROM AUTHOR]