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Stone Crab is a fishery potential obtained from the sea waters of Tarakan City that have not been utilized. These crabs have various morphological variations, so it is necessary to determine the molecular status of the species. Molecular identification is usually made using DNA barcoding techniques. DNA barcoding is a method to determine the taxonomy of organisms molecularly by using DNA chains to identify an organism quickly and accurately. This study aims to genetically identify stone crab samples obtained from the sea waters of Tarakan City and compare their sequences with the GenBank database. DNA extraction was carried out following the protocol of the DNA extraction kit (genomic DNA Purification wizard, Promega). COI gene fragments were amplified by PCR method, using COI Universal Primer. Sequencing was carried out in two directions, forward and reverse with the Sanger termination dideoxy method. The DNA sequencing process is carried out by first Base company in Singapore. The results of the DNA sequence obtained have a length of 599-832 base pairs. The results of the comparison of homology with the NCBI database and the BOLD system show that this sample has similarities with the COI sequences of Myomenippe fornasinii and Myomenippe hardwickii with sim,ilarities reaching 91.56% to 97.22%. The genetic distance obtained from the genetic distance analysis shows that samples C2 and C1 have the closest genetic distance value with a value of 0.019, and the farthest value obtained between samples is C1 and B2, which is 0.041. The results of the phylogenetic analysis showed the formation of 2 clusters. In that cluster, A was filled with samples A1, A2, B2, C1, and C2 and for cluster B was filled with additional data obtained from the NCBI GenBank. [ABSTRACT FROM AUTHOR]

Neutron flux distribution is an essential parameter in the neutronic analysis of the neutron transport in the nuclear reactor. The multi-group diffusion method is the approach commonly used to solve the neutron transport equation. Based on reactor types, the neutron energy range is classified into two regions, namely fast and thermal energy regions. This study presents the neutron flux distribution in the thermal region of the slab reactor core using a one-dimensional multi-group diffusion equation with the Gauss-Seidel iteration method. The reactor is designed in the form of a fast reactor, and it uses the macroscopic cross-sections of the calculation results in the U-PuN fuel cell level as initial input for 70 energy groups. The library data used is JFS-3-J33 70 energy groups, which is the library data of SLAROM computer codes from JAEA Japan. The computational program calculates the neutron flux distribution only in the thermal group of energy: The calculation of neutron flux distributions is executed using the Gauss-Seidel iteration method. The results indicated that the increase of group energy does not reflect the order of magnitude of a multi-group neutron flux distribution in the thermal region. In the case of neutron interaction with U-235 and Pu-239 nuclide, the pattern of neutron flux distribution for each energy group is not sequential, because both are fissile material. Contrary to the U-238 isotope, almost all group energies coincide with one another in the thermal region. The phenomenon occurs because of U-238 is a fertile material that cannot be directly fissioned. [ABSTRACT FROM AUTHOR]