The Main Path to C, N, O Elements in Big Bang Nucleosynthesis

The production of C, N, O elements in a standard big bang nucleosynthesis scenario is investigated. Using the up-to-date data of nuclear reactions in BBN, in particular the Li-8 (n, gamma) Li-9 which has been measured in China Institute of Atomic Energy, a full nucleosynthesis network calculation of BBN is carried out. Our calculation results show that the abundance of C-12 is increased for an order of magnitude after addition of the reaction chain Li-8(n, gamma) Li-9(alpha, n) B-12(beta) C-12, which was neglected in previous studies. We find that this sequence provides the main channel to convert the light elements into C, N, O in standard BBN.

Observation of an Antimatter Hypernucleus

Nuclear collisions recreate conditions in the universe microseconds after the Big Bang. Only a very small fraction of the emitted fragments are light nuclei, but these states are of fundamental interest. We report the observation of antihypertritons-comprising an antiproton, an antineutron, and an antilambda hyperon-produced by colliding gold nuclei at high energy. Our analysis yields 70 +/- 17 antihypertritons (3/Lambda(H) over bar) and 157 +/- 30 hypertritons (H-3(Lambda)). The measured yields of H-3(Lambda) (3/Lambda(H) over bar) and He-3 ((3)(He) over bar) are similar, suggesting an equilibrium in coordinate and momentum space populations of up, down, and strange quarks and antiquarks, unlike the pattern observed at lower collision energies. The production and properties of antinuclei, and of nuclei containing strange quarks, have implications spanning nuclear and particle physics, astrophysics, and cosmology.

Damage assessment and preservation of suspending system of Yongle-Big-Bell

The Yongle-Big-Bell is an exquisite heritage of ancient China and has more than 600 years history. The long history renders the suspending wooden rack serious damage. Therefore, the security is of our great concern. In order to know if the wooden rack is safe or not for the conventional striking in the festival service, a systemic research work has been done. At first the existing deformation and response to the strike of the beetle were measured, and then calculations using method of material mechanics and finite element analysis were conducted. Based on the results of our research, some concluding remarks and suggestion were given: The Yongle-Big-Bell can be struck regularly without urgent danger of collapse. In view of the existence of serious rotten damage, the repair and protection of wooden rack are pressing.

Molecular cloning, expression of a big defensin gene from bay scallop Argopecten irradians and the antimicrobial activity of its recombinant protein

Antimicrobial peptides are important components of the host innate immune responses by exerting broad-spectrum microbicidal activity against pathogenic microbes. The first mollusk big defensin (designated AiBD) cDNA was cloned from bay scallop Argopecten irradians by expressed sequence tag (EST) and rapid amplification of cDNA ends (RACE) techniques. The scallop AiBD consisted of 531 nucleotides with a canonical polyadenylation signal sequence AATAAA and a poly(A) tail, encoding a polypeptide of 122 amino acids. The high similarity of AiBD deduced amino acid sequence with big defensin from Tachypleus tridentatus and Branchiostoma belcheri tsingtaunese indicated that AiBD should be a member of big defensin family. The expression of AiBD in various tissues was measured by using Northern blotting analysis. mRNA transcripts of AiBD could be detected in haemocytes of unchallenged scallops. The temporal expression of AiBD in haemolymph after Vibrio anguilarum challenge was recorded by quantitative real time PCR. The relative expression level of AiBD in haemolymph was up-regulated evenly in the first 8 h, followed by a drastic increase, and increased 131.1-fold at 32 h post-injection. These results indicated that AiBD could be induced by bacterial challenge, and it should participate in the immune responses of A. irradians. Biological activity assay revealed that recombinant AiBD could inhibit the growth of both Gram-positive and Gram-negative bacteria, and also showed strong fungicidal activity towards the expression host. Recombinant expression of AiBD made it possible to further characterize its functions involved in immune responses, and also provided a potential therapeutic agent for disease control in aquaculture. (c) 2006 Elsevier Ltd. All rights reserved.