Nuclear geyser model of the origin of life:Driving force to promote the synthesis of building blocks of life

We propose the nuclear geyser model to elucidate an optimal site to bear the first life.Our model overcomes the difficulties that previously proposed models have encountered.Nuclear geyser is a geyser driven by a natural nuclear reactor,which was likely common in the Hadean Earth,because of a much higher abundance of 235U as nuclear fuel.The nuclear geyser supplies the following：（1）high-density ionizing radiation to promote chemical chain reactions that even tar can be used for intermediate material to restart chemical reactions,（2）a system to maintain the circulation of material and energy,which includes cyclic environmental conditions（warm/cool,dry/wet,etc.）to enable to produce complex organic compounds,（3）a lower temperature than 100℃ as not to break down macromolecular organic compounds,（4）a locally reductive environment depending on rock types exposed along the geyser wall,and（5）a container to confine and accumulate volatile chemicals.These five factors are the necessary conditions that the birth place of life must satisfy.Only the nuclear geyser can meet all five,in contrast to the previously proposed birth sites,such as tidal flat,submarine hydrothermal vent,and outer space.The nuclear reactor and associated geyser,which maintain the circulations of material and energy with its surrounding environment,are regarded as the nuclear geyser system that enables numerous kinds of chemical reactions to synthesize complex organic compounds,and where the most primitive metabolism could be generated.

Effect of Mythimna separata Digestive Fluid on Infectivity of Nuclear Polyhedrosis Virus

The dissolution of polyhedra of Mythimna separata nuclear polyhedrosis. virus by digestive fluid (pH11. 03) collected from the 5th instar M. separata larvae was studied in vitro. Observations were made at timed intervals using phase contrast microscopy and scanning electron microscopy. Under phase contrast microscopy, the polyhcdra lost their refrigence by 5 minute exposure to the digestive fluid. After exposure to the fluid for 30 minutes, all of the PIBs were dissolved. Chages of the PIBs were also observed under scanning electron microscopy, after 5 minute exposure to the fluid, damaged PIBs and PIB-derived debris were seen. After 30 minute exposure, only remains of PIBs were found. The effect of M. separata digestive fluid on the infectivity of Ms NPV was examined by nconatcs bioassay. The results indicated that virions from Ms NPV-PIBs were rapidly inactivated after 15 minute exposure to digestive fluid and all of virions were non-infectious.

Strongly screened electron capture rates of chromium isotopes in presupernova evolution

Taking into account the effect of electron screening on electron energy and electron capture threshold energy, by using the method of Shell-Model Monte Carlo and random phase approximation theory, we investigate the capture rates of chromium isotopes with strong electron screening according to the linear response theory screening model. Strong screening rates can decrease by about 40.43% （e.g., for 6Cr at T9 = 3.44, Ye = 0.43）. Our conclusions may be helpful to researches on supernova explosions and related numerical simulation methods.

Theoretical study on neutron distribution of ^208Pb by parity-violating electron scattering

The precise determination of neutron distribution has important implications for both nuclear structure and nuclear astrophysics. The purpose of this paper is to study the characteristics of neutron distribution of^208 Pb by parity-violating electron scattering（PVS）. Parity-violating asymmetries of^208 Pb with different types of neutron skins are systematically calculated and compared with the experimental data of PREx. The results indicate that the PVS experiments are very sensitive to the nuclear neutron distributions. From further PVS measurements, detailed information on nuclear neutron distributions can be extracted.