Non-uniform fuel distribution and thermo-mechanical analysis of a 1 MW thermal power micronuclear heat pipe reactor.

One of the goals in improving the design of compact portable micronuclear heat pipe reactors is to enhance their operating life so that they can generate maximum power within safe nuclear, thermal, and mechanical limits and with minimal human intervention. This work carries out an analysis to estimate the effect of non-uniform fuel enrichment and thermo-mechanical performance of a 1 MW thermal power uranium nitride fueled Micro Nuclear Heat Pipe Reactor (MNHPR). For neutronic and thermo-mechanical analyses, the open-source Monte Carlo code OpenMC and the COMSOL Multiphysics codes are used. The neutron flux distribution and subsequent fuel temperature, heat transport, stresses and strains are estimated. The analysis of core power distribution shows an uneven power distribution resulting in hot spots. The maximum fuel centerline temperature of 1353 K at the highest peaking factor 1.22 is within the safety limit. However, the high temperature results in higher thermal stress and subsequent displacement of 119 µm that exceeds the 100 µm fuel-clad gap. Power peaking thus significantly limits the maximum allowed operating power. In this study it is found that non-uniform placement of the fuel reduces power peaking and enhances the overall core performance. It is recommended to consider each fuel ring as a separate zone and gradually change the fuel enrichment in each zone. The non-uniform distribution of the fuel follows the gradual increase of enrichment from ring 1 to ring 5 with max enrichment in ring 5, and then a drop in the enrichment to mitigate any peaking in ring 6 due to its proximity to the reflector. From ring 1 to ring 6 fuel of 60-62-70-70-75-65 percent enrichment is recommended. The proposed fuel strategy mitigates power peaking in the core and enhances the maximum safe operating power level by 15 % from 775 kW to 893 kW without physical design change.

Poultry Mites: Ubiquitous, Spreading, and Still a Growing Threat.

Poultry mites continue to be a major threat to poultry meat and egg production all over the world, with some species being blood-feeding arthropods that spend most of their time off-host and others burrowing under the bird's skin. Regardless of feeding strategy, these mites create welfare issues and production losses in poultry production systems in terms of bird growth, egg quality, and egg quantity. Furthermore, some species are able to transmit pathogens, introducing secondary infections that affect the birds' development and survival. Because of national restrictions on acaricide use and the development of mite resistance to available control products, the eradication of poultry mites is far from being achieved. However, new drugs and a better understanding of mite genetic and transcriptomic factors should aid the development of new control and treatment strategies. This review focuses on the main poultry mite species, their significance, and their current and future control.

Estudio recapitulativo- Los ácaros en avicultura: Ubicuos, con continua diseminación y persisten como una amenaza creciente. Los ácaros en avicultura continúan siendo una amenaza importante para la producción de carne de pollo y huevo en todo el mundo y algunas especies son artrópodos hematófagos y pasan la mayor parte de su tiempo fuera del hospedador y otras se esconden debajo de la piel de las aves. Independientemente de la estrategia de alimentación, estos ácaros crean problemas de bienestar y pérdidas de producción en los sistemas de producción avícola en términos de crecimiento de las aves, calidad y cantidad de huevos. Además, algunas especies pueden transmitir patógenos, introduciendo infecciones secundarias que afectan el desarrollo y la supervivencia de las aves. Debido a las restricciones nacionales sobre el uso de acaricidas y el desarrollo de resistencia de los ácaros a los productos de control disponibles, la erradicación de los ácaros de las aves está lejos de lograrse. Sin embargo, los nuevos fármacos y una mejor comprensión de los factores transcriptómicos y genéticos de los ácaros deberían ayudar al desarrollo de nuevas estrategias de control y tratamiento. Esta revisión se centra en las principales especies de ácaros de las aves, su importancia y su control actual y futuro.

Positron-emitting radiotracers spatially resolve unexpected biogeochemical relationships linked with methane oxidation in Arctic soils.

Arctic soils are marked by cryoturbic features, which impact soil-atmosphere methane (CH4 ) dynamics vital to global climate regulation. Cryoturbic diapirism alters C/N chemistry within frost boils by introducing soluble organic carbon and nutrients, potentially influencing microbial CH4 oxidation. CH4 oxidation in soils, however, requires a spatio-temporal convergence of ecological factors to occur. Spatial delineation of microbial activity with respect to these key microbial and biogeochemical factors at relevant scales is experimentally challenging in inherently complex and heterogeneous natural soil matrices. This work aims to overcome this barrier by spatially linking microbial CH4 oxidation with C/N chemistry and metagenomic characteristics. This is achieved by using positron-emitting radiotracers to visualize millimeter-scale active CH4 uptake areas in Arctic soils with and without diapirism. X-ray absorption spectroscopic speciation of active and inactive areas shows CH4 uptake spatially associates with greater proportions of inorganic N in diapiric frost boils. Metagenomic analyses reveal Ralstonia pickettii associates with CH4 uptake across soils along with pertinent CH4 and inorganic N metabolism associated genes. This study highlights the critical relationship between CH4 and N cycles in Arctic soils, with potential implications for better understanding future climate. Furthermore, our experimental framework presents a novel, widely applicable strategy for unraveling ecological relationships underlying greenhouse gas dynamics under global change.

The Role of Ticks in the Emergence of Borrelia burgdorferi as a Zoonotic Pathogen and Its Vector Control: A Global Systemic Review.

Ticks are widely distributed across the globe, serving as hosts for numerous pathogens that make them major contributors to zoonotic parasitosis. Borrelia burgdorferi is a bacterial species that causes an emerging zoonotic tick-borne disease known as Lyme borreliosis. The role of ticks in the transmission of this pathogen was explored in this study. According to this systematic review, undertaken according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 19 tick species are known to carry Borrelia burgdorferi, with more than half of the recorded cases in the last two decades related to Ixodes ricinus and Ixodes scapularis ticks. Forty-six studies from four continents, Europe, North America, Asia, and Africa, reported this pathogen in ticks collected from vegetation, animals, and humans. This study highlights an increasing distribution of tick-associated Borrelia burgdorferi, likely driven by accelerated tick population increases in response to climate change coupled with tick dispersal via migratory birds. This updated catalogue helps in compiling all tick species responsible for the transmission of B. burgdorferi across the globe. Gaps in research exist on Borrelia burgdorferi in continents such as Asia and Africa, and in considering environmentally friendly vector control strategies in Europe and North America.