The coronavirus disease pandemic of 2019 caused by the novel SARS-CoV-2 coronavirus resulted in economic losses and threatened human health worldwide. The pandemic highlights an urgent need for a stable, easily produced, and effective vaccine. SARS-CoV-2 uses the spike protein receptorbinding domain (RBD) to bind its cognate receptor, angiotensinconverting enzyme 2 (ACE2), and initiate membrane fusion. Thus, the RBD is an ideal target for vaccine development. In this study, we designed three different RBD-conjugated nanoparticle vaccine candidates, namely, RBD-Ferritin (24-mer), RBD-mi3 (60-mer), and RBD-I53−50 (120-mer), via covalent conjugation using the SpyTag-SpyCatcher system. When mice were immunized with the RBD-conjugated nanoparticles (NPs) in conjunction with the AddaVax or Sigma Adjuvant System, the resulting antisera exhibited 8-to 120-fold greater neutralizing activity against both a pseudovirus and the authentic virus than those of mice immunized with monomeric RBD. Most importantly, sera from mice immunized with RBD-conjugated NPs more efficiently blocked the binding of RBD to ACE2 in vitro, further corroborating the promising immunization effect. Additionally, the vaccine has distinct advantages in terms of a relatively simple scale-up and flexible assembly. These results illustrate that the SARS-CoV-2 RBD-conjugated nanoparticles developed in this study are a competitive vaccine candidate and that the carrier nanoparticles could be adopted as a universal platform for a future vaccine development.
Aquathermolysis reaction of heavy oils occurring in high temperature water environment significantly degrades the heavy components of heavy oils, improves oil quality and reduces its viscosity. Aerosol, oil-soluble, and water-soluble nickel catalysts obviously and effectively catalyze the aquathermolysis reaction of heavy oils in a high temperature and reduces its viscosity, producing a gas increase of 49%, 41% and 21% respectively compared with the result with the absence of any catalyst. An aerosol, oil-soluble and water-soluble nickel catalyst compound (best quality ratio 1:1:2) increases the oil recovery of heavy oils by 8.5% and decreases the viscosity of sample oil and average relative molecular mass of porous media by 89.6% and 23% respectively, with its resin and asphaltene content significantly reduced. The pilot field tests show that, the test cycle production of heavy oils of each well proves an increase of 81.2 ~ 226.1t (not considering the cycle decline rate) over the previous one, which means that the field tests coincide with the laboratory experiments.
The nanocrystalline powders Nd1-xCaxFeO3 prepared by sol-gel method crystallized as perovskite orthorhombic structure. The mean grain size of Nd1-xCaxFeO3 powders were about 15~ 40 nm. The conductivity of the Ca doped samples was enhanced, compared to that of the undoped. The Nd0.9Ca0.1FeO3-based sensor showed good gas sensing properties to ethanol and acetone. The responses of the Nd0.9Ca0.1FeO3-based sensor to 600ppm ethanol and acetone were about 158.4 at 220°C and 61.7 at 240°C, respectively.
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