Oxidation Analyses of Massive Air Ingress Accident of HTR-PM

The double-ended guillotine break (DEGB) of the horizontal coaxial gas duct accident is a serious air ingress accident of the high temperature gas-cooled reactor pebble-bed module (HTR-PM). Because the graphite is widely used as the structure material and the fuel element matrix of HTR-PM, the oxidation analyses of this severe air ingress accident have got enough attention in the safety analyses of the HTR-PM. The DEGB of the horizontal coaxial gas duct accident is calculated by using the TINTE code in this paper. The results show that the maximum local oxidation of the matrix graphite of spherical fuel elements in the core will firstly reach 3.75⁎104 mol/m3 at about 120 h, which means that only the outer 5 mm fuel-free zone of matrix graphite will be oxidized out. Even at 150 h, the maximum local weight loss ratio of the nuclear grade graphite in the bottom reflectors is only 0.26. Besides, there is enough time to carry out some countermeasures to stop the air ingress during several days. Therefore, the nuclear grade graphite of the bottom reflectors will not be fractured in the DEGB of the horizontal coaxial gas duct accident and the integrity of the HTR-PM can be guaranteed

Expression of CD39 on FoxP3+ T regulatory cells correlates with progression of HBV infection

BACKGROUND: Although it is known that regulatory T cells (Tregs) can suppress the function of effector T cells, and may contribute to impaired immune response, the precise role of Tregs during the course of hepatitis B virus (HBV) infection remains to be elucidated. A newly identified subset of the CD4(+)Foxp3(+ )Tregs, the CD39(+ )Tregs, has been associated with viral infections and autoimmune diseases. Therefore, we hypothesized that this discrete Treg subset may contribute to the chronic infection of HBV. RESULTS: Initial characterization studies of healthy peripheral CD39(+)FoxP3(+)CD4(+ )T cells revealed that the majority were CD45RA(- )Treg cells. Subsequent analysis of HBV-infected patients (38 asymptomatic HBV carriers (AsCs), 37 chronic active hepatitis B (CAH), 29 HBV-associated acute-on-chronic liver failure (ACLF)) and healthy individuals (25 controls) was conducted to assess association with HBV copy number and the liver injury marker alanine aminotransferase (ALT). A higher percentage of CD39(+ )Tregs was detected within the population of FoxP3(+)CD4(+ )T cells in peripheral blood of AsCs patients. Moreover, the percentage of CD39(+ )Tregs was significantly less in CAH and ACLF patients. The increased proportions of circulating CD39(+ )Tregs were positively correlated with serum viral load, but inversely correlated with serum ALT level. CONCLUSION: These findings not only suggest that CD39(+ )Treg cells may be involved in HBV disease progression but also identify CD39(+ )Tregs as a dynamic immune regulatory cell population that may represent a new target of immunomodulatory therapeutic interventions

Researches of Bypass Flows from Cold Plenum to Hot Plenum in HTR-PM by the Flow Network Method

ABSTRACT Many graphite blocks in the core of the HTR-PM serve as the construction material, the neutron reflector and the flow paths of the helium. A small part of helium gas may flow in widely distributed gaps among graphite blocks and enter the hot plenum at low temperature. In our previous paper, a simple flow network combined with CFD simulations of complex flow paths was established to analyze the bypass flow in HTR-PM. In the present paper, the flow network was detailed by assigning more inner nodes and links in the pebble bed. In all kinds of bypass flow paths, only the bypass flow from cold plenum to hot plenum (P-P) was considered. Horizontal flow between the core and the P-P bypass flow path was also added into the flow network in various heights from the top to the bottom. The existence of the horizontal flow enhanced the helium exchange between the core and the bypass flow to different extent in different position, and finally changed the P-P bypass flow ratio. Moreover, gaps in larger sizes had more significant effects on the P-P bypass flows

Activated IL-23/IL-17 pathway closely correlates with increased Foxp3 expression in livers of chronic hepatitis B patients

<p>Abstract</p> <p>Background</p> <p>Foxp3 protein plays a critical role in mediating the inflammatory response and can inhibit the proinflammatory IL-23/IL-17 pathway. However, the molecular interplay of Foxp3 and the IL-23/IL-17 pathway in patients with chronic hepatitis B (CHB) remains unclear. To this end, we analyzed the expression patterns of Foxp3- and IL-23/IL-17 pathway-related proinflammatory cytokines in 39 patients with acute-on-chronic liver failure, 71 patients with CHB and 32 healthy controls.</p> <p>Results</p> <p>Foxp3 expression was found to be elevated in and mainly expressed by the CD4⁺T cell sub-population of peripheral blood mononuclear cells and liver tissues of patients with hepatitis B. The intrahepatic expression of Foxp3 strongly correlated with the copies of HBV DNA and the concentration of surface antigen, HBsAg. IL-23/IL-17 pathway-related proinflammatory cytokines were also found to be significantly increased in patients' liver tissues, as compared to healthy controls. Moreover, Foxp3 expression was strikingly correlated with the production of these cytokines in liver tissues of CHB patients.</p> <p>Conclusions</p> <p>The closely-correlated increase of Foxp3 and IL-23/IL-17 pathway activity in HBV-infected livers suggests that the proinflammatory IL-23/IL-17 pathway had not been effectively suppressed by the host immune machinery, such as Treg (Foxp3) cells. Constitutive activation of the IL-23/17 pathway, thus, may support the chronic hepatitis B state.</p

Enabling and scaling biomolecular simulations of 100 million atoms on petascale machines with a multicore-optimized message-driven runtime

A 100-million-atom biomolecular simulation with NAMD is one of the three benchmarks for the NSF-funded sustainable petascale machine. Simulating this large molecular system on a petascale machine presents great challenges, including handling I/O, large memory footprint and getting good strong-scaling results. In this paper, we present parallel I/O techniques to enable the simula-tion. A new SMP model is designed to efficiently utilize ubiquitous wide multicore clusters by extending the CHARM++ asynchronous message-driven runtime. We exploit node-aware techniques to op-timize both the application and the underlying SMP runtime. Hi-erarchical load balancing is further exploited to scale NAMD to the full Jaguar PF Cray XT5 (224,076 cores) at Oak Ridge Na-tional Laboratory, both with and without PME full electrostatics, achieving 93 % parallel efficiency (vs 6720 cores) at 9 ms per step for a simple cutoff calculation. Excellent scaling is also obtained on 65,536 cores of the Intrepid Blue Gene/P at Argonne National Laboratory. 1

A 5'-proximal Stem-loop Structure of 5' Untranslated Region of Porcine Reproductive and Respiratory Syndrome Virus Genome Is Key for Virus Replication

<p>Abstract</p> <p>Background</p> <p>It has been well documented that the 5' untranslated region (5' UTR) of many positive-stranded RNA viruses contain key <it>cis</it>-acting regulatory sequences, as well as high-order structural elements. Little is known for such regulatory elements controlling porcine arterivirus replication. We investigated the roles of a conserved stem-loop 2 (SL2) that resides in the 5'UTR of the genome of a type II porcine reproductive and respiratory syndrome virus (PRRSV).</p> <p>Results</p> <p>We provided genetic evidences demonstrating that 1) the SL2 in type II PRRSV 5' UTR, N-SL2, could be structurally and functionally substituted by its counterpart in type I PRRSV, E-SL2; 2) the functionality of N-SL2 was dependent upon the G-C rich stem structure, while the ternary-loop size was irrelevant to RNA synthesis; 3) serial deletions showed that the stem integrity of N-SL2 was crucial for subgenomic mRNA synthesis; and 4) when extensive base-pairs in the stem region was deleted, an alternative N-SL2-like structure with different sequence was utilized for virus replication.</p> <p>Conclusion</p> <p>Taken together, we concluded that the phylogenetically conserved SL2 in the 5' UTR was crucial for PRRSV virus replication, subgenomic mRNA synthesis in particular.</p