Abstract: A modified cutinase is disclosed. The cutinase has the modified amino acid sequence of SEQ ID NO: 2, wherein the modification is a substitution of asparagine at position 181 with alanine, or substitutions of asparagine at position 181 with alanine and phenylalanine at position 235 with leucine. The modified enzyme has improved PET-hydrolytic activity, and thus, the high-activity PET hydrolase is obtained, and the industrial application value of the PET hydrolase is enhanced.

Abstract: The present invention discloses a method for leak detection and location for fluid pipelines, comprising a pipeline to be detected, characterized in that the pipeline to be detected is at least provided with two sensing devices having a certain distance therebetween. Acquisition points are formed at the positions of the sensing devices. The sensing devices can simultaneously sense acoustic vibrations of the pipeline in two directions, i.e., axial direction and radial direction of the pipeline, respectively. When there is a leak point in the pipeline to be detected between the two acquisition points, locating the leak point is performed according to the following formula: ? { ? L ? ? 12 ? V L + l 1 - l 2 = 0 ? T ? ? 12 ? V T + l 1 - l 2 = 0 ? 2 ? l 1 - ? 1 ? l 2 = 0 l 1 + l 2 = L .

Abstract: The invention provides methods to assay and regulate the replication of hepatitis B virus (HBV), employing methods of generating HBV replication mutants. Based on the polymerase gene of HBV strains, various primers were designed, and by using restriction enzymes and polymerase chain reaction, fragments of the polymerase gene were substituted, and the replicative competency of the newly constructed recombinant polymerase gene was analyzed. This invention can be used to look for new functional domains in the polymerase and for designing anti-HBV replicating drugs and diagnostic reagents.

Abstract: This invention is a vaccine prepared from antigen-antibody-recombinant plasmid DNA complex. This invention is a complex vaccine composed of at least one microbial source antigen and its (their) specific antibody or specific immunoglobulin complexed with one or more recombinant DNA(s) from the gene or genes of microbes. Immunization with this complex vaccine induces enhanced specific humoral and cellular immune responses in infected individuals with immune tolerance or immune defects against specific microbial infections. The advantages of this complex vaccine are: antigen presentation via various modes; more rapid induction of immune responses; less amount of components required to induce immune responses; increased stability of the vaccine; and can be applied by injection, intranasal or other routes of topical immunization.