Modification of intergrain connectivity, upper critical field anisotropy, and critical current density in ion irradiated MgB2 films

We study the effect of 100 MeV Silicon and 200 MeV Gold ion irradiation on the inter and intra grain properties of superconducting thin films of Magnesium Diboride. Substantial decrease in inter-grain connectivity is observed, depending on irradiation dose and type of ions used. We establish that modification of sigma band scattering mechanism, and consequently the upper critical field and anisotropy, depends on the size and directional properties of the extrinsic defects. Post heavy ion irradiation, the upper critical field shows enhancement at a defect density that is five orders of magnitude less compared to neutron irradiation. The critical current density however is best improved through light ion irradiation.Comment: 18 pages, 4 figures, submitte

Deactivation study of the hydrodeoxygenation of p-methylguaiacol over silica supported rhodium and platinum catalysts

Hydrodeoxygenation of para-methylguaiacol using silica supported Rh or Pt catalysts was investigated using a fixed-bed reactor at 300 °C, under 4 barg hydrogen and a WHSV of 2.5 h−1. The activity, selectivity and deactivation of the catalysts were examined in relation to time on stream. Three catalysts were tested: 2.5% Rh/silica supplied by Johnson Matthey (JM), 2.5% Rh/silica and 1.55% Pt/silica both prepared in-house. The Rh/silica (JM) showed the best stability with steady-state reached after 6 h on stream and a constant activity over 3 days of reaction. In contrast the other two catalysts did not reach steady state within the timeframe of the tests, with continuous deactivation over the time on stream. Nevertheless higher coking was observed on the Rh/silica (JM) catalyst, while all three catalysts showed evidence of sintering. The Pt catalyst (A) showed higher selectivity for the production of 4-methylcatechol while the Rh catalysts were more selective toward the cresols. In all cases, complete hydrodeoxygenation of the methylguaiacol to methylcyclohexane was not observed

Genetic structure among four populations of paddlefish, Polyodon spathula (Actinopterygii: Acipenseriformes: Polyodontidae), based on disomic microsatellite markers

Background. The paddlefish, Polyodon spathula (Walbaum, 1792), is an important species for commercial and recreational fisheries throughout the central United States. Populations have declined in many areas due to river modification, loss of spawning habitat, pollution, and over-exploitation. Assessing genetic diversity of a species is an important consideration for developing conservation plans. The goal of this research was to perform a broad range survey of paddlefish diversity by evaluating populations from geographically distant major rivers of the United States of America. Materials and methods. Paddlefish samples were collected from four sites including the Alabama River, Red River, Yellowstone/Missouri River, and Ohio River. Eight microsatellite loci (PspD102, PspD111, PspB105, PspD9, PspD8, PspC6, PspH26, and PspC10) that displayed disomic inheritance patterns were used for the amplification of alleles. Results. Average allelic richness of four sites ranged from 7.50 ± 1.36 to 5.46 ± 0.91. Average expected heterozygosity ranged from 0.717 ± 0.085 to 0.591 ± 0.093, the average observed heterozygosity assumed the values from 0.711 ± 0.115 to 0.585 ± 0.087. A moderate level of between population diversity was observed with an overall Fst value of 0.0702. Hardy–Weinberg equilibrium revealed that seven loci in the four populations were in equilibrium. The four populations were clustered to two categories by cluster analysis (UPGMA) based on Fst and δμ2 distance. Conclusion. Four studied paddlefish populations exhibited relatively low levels of genetic diversity and close relative relations, but still had some differentiation among the populations. The genetic distance and Fst revealed that the Ohio River, Red River and Yellowstone/Missouri River populations belong to the same branch, while the Alabama River population from another branch

Transparent Incremental Updates for Genomics Data Analysis Pipelines

A large up-to-date compendium of integrated genomic data is often required for biological data analysis. The compendium can be tens of terabytes in size, and must often be frequently updated with new experimental or meta-data. Manual compendium update is cumbersome, requires a lot of unnecessary computation, and it may result in errors or inconsistencies in the compendium. We propose a transparent file based approach for adding incremental update ca-pabilities to unmodified genomics data analysis tools and pipeline workflow managers. This approach is implemented in the GeStore system. We evaluate GeStore using a real world genomics compendium. Our results show that it is easy to add incremental updates to genomics data processing pipelines, and that incremental updates can reduce the computation time such that it becomes prac-tical to maintain large-scale up-to-date genomics compendia on small clusters