Antigenic and immunogenic changes due to mutation of sgene of HBV

AIM: To investigate the change of immunological characteristics of HBsAg caused by the mutation at codon 145 of HBsAg using DNA-based immunization.METHODS: Plasmids expressing mutant and wild type envelope antigens were transfected into human hepatocellular carcinoma cells via electrotransformation. The antigenicity of HBsAg was studied with EIA and immunocytochemical staining. Then plasmids were used to immunize 5 C57BL/6 mice. Sera of mice were detected for anti-HBs and anti-preS2with ELISA. RESULTS: The mutant HBsAg could be detected by native antibody in EIA and immunocytochemical study. But the A(450nm) value of the mutant HBsAg in the supernatant was apparently lower than that of the wild-type. Both mutant and native HBsAg expression plasmid could stimulate a strong humoral immune response to HBsAg and preS2 antigen in mice. Protective antibodies against HBsAg elicited by the native HBsAg occurred earlier than that elicited by the mutant HBsAg about one to two weeks. The occurrence of protective antibodies against preS2 antigen was one to two weeks earlier than that of anti-HBs.CONCLUSION: The amino acid substitution causes changes of the antigenicity and immunogenicity of HBsAg, but mutant HBsAg can still induce a protective humoral immune responsein mice.

Processing and Microstructural Evolution of Superalloy Inconel 718 during Hot Tube Extrusion

The processing parameters of tube extrusion for superalloy Inconel 718 (IN 718), such as slug temperature, tools temperature, choice of lubricant, extrusion ratio and extrusion speed, were determined by experiment in this paper. An appropriate temperature range recommended for the slug is 1080-1120℃, and the temperature range recommended for the tools is 350-500℃. The microstructural evolution of superalloy IN 718 during tube extrusion was analyzed. With the increase of the deformation the cross crystal grains were slightly refined. While the vertical crystal grain is elongated evidently and the tensile strength increased along the axial rake. Glass lubricants have to be spread on the slug surface after being heated to 150-200℃, vegetable oil or animal oil can be used as the lubricant on the surface of the tools to reduce the extrusion force remarkably.

Determination of Feature Line Equation for Self-adapting Incremental Press Bending

The basie idea and method about determination of the feature line equations and how to apply them to the numerical control of the press bending of panei skins were introduced. Research indicates that it is feasible to realize the self adapting incremental press bending by adopting the feature line equation. The feature line equation, which is based on the database of the status of practical processes, can be adjusted in time, and the forming precision can be improved. It is important to correctly select and reasonably predict the feature line equations to enhance the accuracy of the incremental press bending based on the feature line database and algorithm. The determination of the feature line equation settles necessary data foundation for further research on the database of self-adapting incremental press bending, and it supplies a new clue for the development of self-adapting incremental press bending.

Hardening of Thermal Photons Through Inverse Compton Scattering in Strong Magnetic Fields

A new spectrum function is obtained by use of the Compton scattering cross section in the laboratory frame derived earlier. This spectrum function, besides some modifications in the coefficients of the resonant term, contains also a non-resonant term which is inversely proportional to the square of the magnetic field. Based on this spectrum function, the hardening of thermal photons through inverse Compton scattering by relativistic electron beams on the surface of a strongly magnetized neutron star is investigated. Two new features are found. First, there is a maximum scattered photon energy for a given resonant scattering, beyond which resonance disappears. This maximum depends on the electron energy and the magnetic field, but is independent of the incident photon energy. Second, beyond each resonant scattering, there is a high-energy tail, resulting from non-resonant scattering. It is also found that all the tails have a common upper limit which is the highest scattered photon energy for the given incident photon and electron energies. These two new features are absent in the Monte Carlo simulations and therefore, may have physical implications for y-ray emissions.