Enhanced critical current density of MgB2 superconductor synthesized in high magnetic fields

The effect of high magnetic fields on the current carrying properties of both MgB2 bulks and Fe-sheathed tapes was investigated following different thermal sequences. It is found that application of a large magnetic field during processing results in the quite uniform microstructure and the better connectivity between the MgB2 grains. As a result, the Jc of these samples has shown much higher value than that of the MgB2 samples in the absence of magnetic field. The possible mechanism of the Jc enhancement under an external magnetic field is also discussed.Comment: Presented at ISS2005, Tsukuba, 24-26 Oct., 2005; Revised versio

MICROBIOLOGICAL ASSESSMENT OF ORGANIC PRODUCE PRE- AND POST- HARVEST ON MARYLAND FARMS AND IMPACT OF GROWING AND HANDLING METHODS ON EPIPHYTIC BACTERIA

Although the consumption of organic produce has dramatically increased in recent years and many outbreaks continue to occur, the microbiological safety of organic produce has not been fully assessed. This study generated microbiological data to evaluate organic produce safety and also assessed the impact of growing methods (ground cover effects) and handling methods (washing practices) in organic lettuce systems. The study evaluated microbiological safety of pre- and post-harvest fresh produce samples from small organic farms in Maryland, the effect of mulching on survival of indicator bacteria and the impact of post-harvest washing method on microbiological safety and epiphytic bacterial communities. Results indicate that (1) washed post-harvest produce had higher risks than unwashed and pre-harvest organic produce as measured by indicator bacteria E. coli, total coliforms, APC, yeast and mold; (2) different mulches affected the microbial levels differently; (3) different washing methods altered the bacterial communities both immediately and following 5 days of storage. This study presents data that could be used to assess food safety risks of organic produce associated with their cultivation and on-farm handling practices

2,2′-(Diselane-1,2-di­yl)dinicotinamide N,N′-dimethyl­formamide disolvate

The asymmetric unit of the title compound, C12H10N4O2Se2·2C3H7NO, contains two solvent mol­ecules and two half mol­ecules of the dinicotinamide, each of which sits on a center of symmetry passing through the middle of the Se—Se bond. In each mol­ecule, the two pyridyl groups and diseleno group are approximately coplanar (r.m.s. deviations from planarity for all non-H atoms = 0.011 and 0.008 Å in the two mol­ecules). Inter­molecular N—H⋯O hydrogen bonds stablilize the crystal packing

Effect of nano-C doping on the in-situ processed MgB2 tapes

The effect of nano-C doping on the microstructure and superconducting properties of Fe-sheathed MgB2 tapes prepared through the in-situ powder-in-tube method was studied. Heat treatment was performed at a low temperature of 650C for 1 h. Scanning electron microscopy investigation revealed that the smaller grain size of MgB2 in the samples with the C-doping. Further, the a-axis lattice parameter and transition temperature decreased monotonically with increasing doping level, which is due to the C substitution for B. High critical current density Jc values in magnetic fields were achieved in the doped samples because of the very fine-grained microstructure of the superconducting phase obtained with C doping.Comment: revised manuscript, 4 pages, 4 figures. to be published soo

How Well Does the ERA5 Reanalysis Capture the Extreme Climate Events Over China? Part I: Extreme Precipitation

ERA5 is the fifth-generation atmospheric reanalysis of the European Center for Medium-Range Weather Forecasts, with high spatiotemporal resolution and global coverage. However, the reliability of ERA5 for simulating extreme precipitation events is still unclear over China. In this study, 12 extreme precipitation indices and a comprehensive quantitative distance between indices of simulation and observation were used to evaluate ERA5 precipitation from three fundamental aspects: intensity, frequency, and duration. The geomorphological regionalization method was used to divide the subregions of China. The results showed that the ability of ERA5 to simulate annual total precipitation was better than that of daily precipitation. For the intensity indices, ERA5 performs well for simulating the PRCPTOT (annual total wet days precipitation) over China. ERA5 performs better on RX5day (max 5-days precipitation amount) and R95p (very wet days), especially in eastern China, than on RX1day (max 1-day precipitation amount) and R99p (extremely wet days). For the frequency indices, the ability of the ERA5 simulation increased as the amount of precipitation increased, except for northwestern China. However, the ability of ERA5 to simulate R50 mm (number of extreme heavy precipitation days) decreased. For the duration indices, ERA5 was better at simulating drought events than wet events in eastern China. Our results highlight the need for ERA5 to enhance the simulation of trend changes in extreme precipitation events

Ambient particulate air pollution induces oxidative stress and alterations of mitochondria and gene expression in brown and white adipose tissues

<p>Abstract</p> <p>Background</p> <p>Prior studies have demonstrated a link between air pollution and metabolic diseases such as type II diabetes. Changes in adipose tissue and its mitochondrial content/function are closely associated with the development of insulin resistance and attendant metabolic complications. We investigated changes in adipose tissue structure and function in brown and white adipose depots in response to chronic ambient air pollutant exposure in a rodent model.</p> <p>Methods</p> <p>Male ApoE knockout (ApoE^-/-) mice inhaled concentrated fine ambient PM (PM < 2.5 μm in aerodynamic diameter; PM_2.5) or filtered air (FA) for 6 hours/day, 5 days/week, for 2 months. We examined superoxide production by dihydroethidium staining; inflammatory responses by immunohistochemistry; and changes in white and brown adipocyte-specific gene profiles by real-time PCR and mitochondria by transmission electron microscopy in response to PM_2.5exposure in different adipose depots of ApoE^-/-mice to understand responses to chronic inhalational stimuli.</p> <p>Results</p> <p>Exposure to PM_2.5induced an increase in the production of reactive oxygen species (ROS) in brown adipose depots. Additionally, exposure to PM_2.5decreased expression of uncoupling protein 1 in brown adipose tissue as measured by immunohistochemistry and Western blot. Mitochondrial number was significantly reduced in white (WAT) and brown adipose tissues (BAT), while mitochondrial size was also reduced in BAT. In BAT, PM_2.5exposure down-regulated brown adipocyte-specific genes, while white adipocyte-specific genes were differentially up-regulated.</p> <p>Conclusions</p> <p>PM_2.5exposure triggers oxidative stress in BAT, and results in key alterations in mitochondrial gene expression and mitochondrial alterations that are pronounced in BAT. We postulate that exposure to PM_2.5may induce imbalance between white and brown adipose tissue functionality and thereby predispose to metabolic dysfunction.</p

How Well Does the ERA5 Reanalysis Capture the Extreme Climate Events Over China? Part II: Extreme Temperature

The fifth-generation atmospheric reanalysis of the European Center for Medium-Range Weather Forecasts (ERA5) is the latest reanalysis product. However, the reliability of ERA5 to capture extreme temperatures is still unclear over China. Hence, based on conventional meteorological station data, a new criterion (DISO) was used to validate the ERA5 capturing extreme temperature indices derived from the Expert Team on Climate Change Detection and Indices (ETCCDI) across the six subregions of China on different timescales. The conclusions are as follows: the original daily temperatures (mean temperature, maximum temperature, and minimum temperature) can be well reproduced by ERA5 reanalysis over China. ERA5 tends to exhibit more misdetection for the duration of extreme temperature events than extreme temperature intensity and frequency. In addition, ERA5 performed best in the summer and worst in the winter, respectively. The trend of absolute indices (e.g., TXx and TNx), percentile-based indices (e.g., TX90p, TX10p, TN90p, and TN10p), and duration indices (e.g., WSDI, CSDI, and GSL) can be captured by ERA5, but ERA5 failed to capture the tendency of the diurnal temperature range (DTR) over China. Spatially, ERA5 performs well in southeastern China. However, it remains challenging to accurately recreate the extreme temperature events in the Tibetan Plateau. The elevation difference between the station and ERA5 grid point contributes to the main bias of reanalysis temperatures. The accuracy of ERA5 decreases with the increase in elevation discrepancy

SMA1, a homolog of the splicing factor Prp28, has a multifaceted role in miRNA biogenesis in Arabidopsis

MicroRNAs (miRNAs) are a class of small non-coding RNAs that repress gene expression. In plants, the RNase III enzyme Dicer-like (DCL1) processes primary miRNAs (pri-miRNAs) into miRNAs. Here, we show that SMALL1 (SMA1), a homolog of the DEADbox pre-mRNA splicing factor Prp28, plays essential roles in miRNA biogenesis in Arabidopsis. A hypomorphic sma1-1 mutation causes growth defects and reduces miRNA accumulation correlated with increased target transcript levels. SMA1 interacts with the DCL1 complex and positively influences primiRNA processing. Moreover, SMA1 binds the promoter region of genes encoding pri-miRNAs (MIRs) and is required for MIR transcription. Furthermore, SMA1 also enhances the abundance of the DCL1 protein levels through promoting the splicing of the DCL1 pre-mRNAs. Collectively, our data provide new insights into the function of SMA1/Prp28 in regulating miRNA abundance in plants