•Thermal behavior of the disassembled fuel channel of Indian PHWR under severe core accident conditions.•Steam ingression effects on horizontal disassembled fuel channel.•Numerical simulation is also ...performed and compared with experimental results.•Hydrogen generation during such accidents are measured and compared theoretically.•Hydrogen generation rate is found to be 0.01822 g/s, and oxidation is limited to ends only.
A postulated scenario of station blackout (SBO) or loss of coolant accidents (LOCA) with the failure of all safety systems can lead to the unmitigated severe accident in pressurized heavy water reactors (PHWRs). As water is present as moderator in the Calandria vessel participates in decay heat removal hence it undergoes boil off. This initiates the slow uncovering of the top channels. Continuous heating of exposed channels may lead to disassembly of the channels. Under such circumstances, the steam can ingress inside the disassembled channels and react with unreacted zirconium and generate more hydrogen.
The present paper aims to assess the thermal behavior, steam ingression inside the channel and associated hydrogen generation of standard 220 MWe Indian PHWR under the hypothesis of postulated severe accidents with large break LOCA and loss of ECCS as an initiating event. Experimental and numerical study has been carried out for a one-meter channel length for 2% of decay power level. Transient CFD simulation is also performed for a better understanding of the thermal behavior of the channel. Throughout the transient, the fuel bundle of the channel is heated maximum up to the temperature 891 °C, and generation of hydrogen is observed beyond maximum temperature of the fuel bundle of 628 °C. The average hydrogen generation rate is found to be 0.01822 g/s. The experiment shows that oxidation due to steam ingression is limited to the regions near the end of the channels. Radiation and convective steam cooling helps to limit the rise in the temperature of the fuel bundle. Ingression effect is noticed up to 260 mm from ends, beyond which limited steam is available.
Thermally induced errors account for the majority of fabrication accuracy loss in an uncompensated machine tool. This issue is particularly relevant in the micro-machining arena due to the comparable ...size of thermal errors and the characteristic dimensions of the parts under fabrication. A spindle of a micro-milling machine tool is one of the main sources of thermal errors. Other sources of thermal errors include drive elements like linear motors and bearings, the machining process itself and external thermal influences such as variation in ambient temperature. The basic strategy for alleviating the magnitude of these thermal errors can be achieved by thermal desensitization, control and compensation within the machine tool.
This paper describes a spindle growth compensation scheme that aims towards reducing its thermally-induced machining errors. The implementation of this scheme is simple in nature and it can be easily and quickly executed in an industrial environment with minimal investment of manpower and component modifications.
Initially a finite element analysis (FEA) is conducted on the spindle assembly. This FEA correlates the temperature rise, due to heating from the spindle bearings and the motor, to the resulting structural deformation. Additionally, the structural deformation of the spindle along with temperature change at its various critical points is experimentally obtained by a system of thermocouples and capacitance gages.
The experimental values of the temperature changes and the structural deformation of the spindle qualitatively agree well with the results obtained by FEA. Consequently, a thermal displacement model of the high-speed micro-milling spindle is formulated from the previously obtained experimental results that effectively predict the spindle displacement under varying spindle speeds. The implementation of this model in the machine tool under investigation is expected to reduce its thermally induced spindle displacement by 80%, from 6
microns to less than 1 micron in a randomly generated test with varying spindle speeds.
This is a meeting report of the workshop on the tectonics of the Shillong Plateau and the Brahmaputra Valley organized by the Department of Geology, University of Calcutta on 21 November 2014. It was ...attended by a number of earth scientists actively working on this region.The Shillong Plateau is one of the tectonic enigmas on the Indian subcontinent. Its relation with the Himalayan orogenesis, in particular the mechanism of its uplift with respect to the virtually nonexistent Himalayan foredeep to the north and the Bengal Basin to the south has remained a hotly debated topic
Arsenic contamination in groundwater is becoming more and more a worldwide problem. Nearing 50 million of people are at health risk from arsenic contamination at Ganga–Meghna–Bramhaputra basin. The ...experimental results of the five blocks under Malda district of West Bengal, India, showed that the arsenic concentration in groundwater (0.41–1.01 mg/l) was higher than the permissible limit for drinking water (0.01 mg/l) (WHO) and FAO (Food and Agriculture Organization) permissible limit for irrigation water (0.10 mg/l). The soil arsenic level (13.12 mg/kg) crossed the global average (10.0 mg/kg), but within the maximum acceptable limit for agricultural soil (20.0 mg/kg) recommended by the European Union. The total arsenic concentration on food crops varied from 0.000 to 1.464 mg/kg of dry weight. The highest mean arsenic concentration was found in potato (0.456 mg/kg), followed by rice grain (0.429 mg/kg). The total mean arsenic content (milligrams per kg dry weight) in cereals ranged from 0.121 to 0.429 mg/kg, in pulses and oilseeds ranged from 0.076 to 0.168 mg/kg, in tuber crops ranged from 0.243 to 0.456 mg/kg, in spices ranged from 0.031 to 0.175 mg/kg, in fruits ranged from 0.021 to 0.145 mg/kg and in vegetables ranged from 0.032 to 0.411 mg/kg, respectively. Hence, arsenic accumulation in cereals, pulses, oilseed, vegetables, spices, cole crop and fruits crop might not be safe in future without any sustainable mitigation strategies to avert the potential arsenic toxicity on the human health in the contaminated areas.
This study investigates the kinked exponential growth, degree of association, and causation between economic growth, energy consumption, population, trade openness, and carbon dioxide (CO
2
) ...emissions in 25 upper middle-income group countries spanning data from 1985 to 2014. The study employed first-generation and second-generation unit root tests; prior to that, the cross-sectional dependence test is also applied and panel cointegration techniques, panel FMOLS and DOLS, and panel causality techniques are employed to test the degree of association and causation among the variables. The study reveals a long-run cointegration among the variables. Results of FMOLS declare that there are negative associations between economic growth and CO
2
emissions, trade openness, and carbon dioxide emissions respectively, whereas it was found that there are positive relations between energy consumption and CO
2
emissions, population, and CO
2
emissions. While analyzing the association through DOLS, we find that all the selected determinants of carbon dioxide emissions are directly proportional to CO
2
emissions in these countries. The panel Granger causality test indicates that there is bi-directional causality between population and economic growth and between trade openness and economic growth. Finally, the study ends with some policy suggestions and new avenues for future research.
Agriculture plays a key role in the overall economic and social wellbeing in Africa. Now, Africa appears to emerge as a key player in food production because there exists enormous unused land for ...cultivation. On the basis of availability of data, this study aims at investigating the impact of the climate change on rice production in the twenty-five African countries from 2002 to 2014 following a static panel data approach using World Bank and Food and Agricultural Organization (FAO) data. Considering CO2 (Carbon Di Oxide) emissions as average precipitation in depth and temperature change as climate change indicators along with other control variables such as fertilizer consumption and use of pesticides, this study observes that these climate indicators have significant adverse impact in explaining variations in spatial and temporal change in rice production in African countries. It may be demonstrated from the empirical analysis that those climate variables like CO2 emissions, pesticide use and temperature change are statistically significant at a 5 %, 10 % and 5 % levels, respectively. All the indicators have negative effects on rice production in African countries. The coefficients associated with these indicators are negative and statistically significant indicating that higher CO2 emissions adversely affect rice production in Africa. Moreover, pesticides used per kg in production have an inverse relation with rice production in this continent. Further, temperature harms rice production in African countries. Temperature changes negatively affect rice production as indicated by its coefficient value being -199958.10. The results also demonstrate that adaptation of new rice seed varieties that are more tolerant to higher temperature will be more effective in response to climate change. The study suggests that there is need for enormous development in the agriculture sector, to reach the ultimate goal. In particular, development of irrigation system and large-scale funding by the government in African countries is required. Key words: Rice Production, Climate Change, Static Panel Approach, Average Precipitation
Elevated O-GlcNAcylation is associated with disease states such as diabetes and cancer. O-GlcNAc transferase (OGT) is elevated in multiple cancers and inhibition of this enzyme genetically or ...pharmacologically inhibits oncogenesis. Here we show that O-GlcNAcylation modulates lipid metabolism in cancer cells. OGT regulates expression of the master lipid regulator the transcription factor sterol regulatory element binding protein 1 (SREBP-1) and its transcriptional targets both in cancer and lipogenic tissue. OGT regulates SREBP-1 protein expression via AMP-activated protein kinase (AMPK). SREBP-1 is critical for OGT-mediated regulation of cell survival and of lipid synthesis, as overexpression of SREBP-1 rescues lipogenic defects associated with OGT suppression, and tumor growth in vitro and in vivo. These results unravel a previously unidentified link between O-GlcNAcylation, lipid metabolism and the regulation of SREBP-1 in cancer and suggests a crucial role for O-GlcNAc signaling in transducing nutritional state to regulate lipid metabolism.
Glioblastoma multiforme (GBM) is the most lethal form of brain cancer with a median survival of only 12 to 15 months. Current standard treatment consists of surgery followed by chemoradiation. The ...poor survival of patients with GBM is due to aggressive tumor invasiveness, an inability to remove all tumor tissue, and an innate tumor chemo- and radioresistance. Ataxia-telangiectasia mutated (ATM) is an excellent target for radiosensitizing GBM because of its critical role in regulating the DNA damage response and p53, among other cellular processes. As a first step toward this goal, we recently showed that the novel ATM kinase inhibitor KU-60019 reduced migration, invasion, and growth, and potently radiosensitized human glioma cells in vitro.
Using orthotopic xenograft models of GBM, we now show that KU-60019 is also an effective radiosensitizer in vivo. Human glioma cells expressing reporter genes for monitoring tumor growth and dispersal were grown intracranially, and KU-60019 was administered intratumorally by convection-enhanced delivery or osmotic pump.
Our results show that the combined effect of KU-60019 and radiation significantly increased survival of mice 2- to 3-fold over controls. Importantly, we show that glioma with mutant p53 is much more sensitive to KU-60019 radiosensitization than genetically matched wild-type glioma.
Taken together, our results suggest that an ATM kinase inhibitor may be an effective radiosensitizer and adjuvant therapy for patients with mutant p53 brain cancers.
Motivation: Interaction among time series can be explored in many ways. All the approach has the usual problem of low power and high dimensional model. Here we attempted to build a causality network ...among a set of time series. The causality has been established by Granger causality, and then constructing the pathway has been implemented by finding the Minimal Spanning Tree within each connected component of the inferred network. False discovery rate measurement has been used to identify the most significant causalities. Results: Simulation shows good convergence and accuracy of the algorithm. Robustness of the procedure has been demonstrated by applying the algorithm in a non-stationary time series setup. Application of the algorithm in a real dataset identified many causalities, with some overlap with previously known ones. Assembled network of the genes reveals features of the network that are common wisdom about naturally occurring networks. Contact:nitai@lilly.com; chatterjee@stat.umn.edu
It is well established that prokaryotes and eukaryotes alike utilize phosphotransfer to regulate cellular functions. One method by which this occurs is via eukaryote-like serine/threonine kinase ...(ESTK)- and phosphatase (ESTP)-regulated pathways. The role of these enzymes in Staphylococcus aureus has not yet been examined. This resilient organism is a common cause of hospital-acquired and community-associated infections, infecting immunocompromised and immunocompetent hosts alike. In this study, we have characterized a major functional ESTK (STK) and ESTP (STP) in S. aureus and found them to be critical modulators of cell wall structure and susceptibility to cell wall-acting β-lactam antibiotics. By utilizing gene knockout strategies, we created S. aureus N315 mutants lacking STP and/or STK. The strain lacking both STP and STK displayed notable cell division defects, including multiple and incomplete septa, bulging, and irregular cell size, as observed by transmission electron microscopy. Mutants lacking STP alone displayed thickened cell walls and increased resistance to the peptidoglycan-targeting glycylglycine endopeptidase lysostaphin, compared to the wild type. Additionally, mutant strains lacking STK or both STK and STP displayed increased sensitivity to cell wall-acting cephalosporin and carbapenem antibiotics. Together, these results indicate that S. aureus STK- and STP-mediated reversible phosphorylation reactions play a critical role in proper cell wall architecture, and thus the modulation of antimicrobial resistance, in S. aureus.
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