Abstract: A SiC ohmic contact preparation method is provided and includes: selecting a SiC substrate; preparing a graphene/SiC structure by forming a graphene on a Si-face of the SiC substrate; depositing an Au film on the graphene of the graphene/SiC structure; forming a first transfer electrode pattern on the Au film by a first photolithography; etching the Au film uncovered by the first transfer electrode pattern through a wet etching; etching the graphene uncovered by the Au film through a plasma etching after the wet etching; forming a second transfer electrode pattern on the SiC substrate by a second photolithography; depositing an Au material on the Au film exposed by the second transfer electrode pattern and forming an Au electrode and then annealing. The graphene reduces potential barrier associated with the SiC interface, specific contact resistance of ohmic contact reaches the order of 10?7˜10?8 ?·cm2, and the method has high repeatability.

Abstract: Provided is a gas water heater. The gas water heater includes a pre-mixer, a combustor having a combustion chamber in communication with a premixing chamber, a condensate water assembly configured to receive and discharge condensate water, and an apparatus for controlling the gas water heater. The pre-mixer includes a premixing chamber and an air intake fan that is configured to supply air to the combustion chamber. The air intake fan is disposed in the premixing chamber. The method includes: acquiring an intake air pressure threshold; acquiring an air intake pressure value of the air intake fan; and controlling, in response to determining based on the air intake pressure value and the intake air pressure threshold that a water seal of the condensate water assembly is at risk of being blown away, the gas water heater to stop operation.

Abstract: Disclosed is a method for improving the immunogenicity of a protein/peptide antigen, the method comprising conjugating a protein/peptide antigen with a sugar to form a sugar-protein/peptide antigen conjugate, which has improved immunogenicity compared to an unconjugated protein/peptide antigen. In particular, the method involves conjugating a pathogen, such as a viral surface protein antigen or a fragment thereof, with a polysaccharide, in particular a capsular polysaccharide of Streptococcus pneumonia. The conjugate with improved immunogenicity can be used to prevent or treat diseases caused by pathogens, in particular diseases caused by coronaviruses.