792 research outputs found

    Solar microwave millisecond spike at 2.84 GHz

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    Using the high time resolution of 1 ms, the data of solar microwave millisecond spike (MMS) event was recorded more than two hundred times at the frequency of 2.84 GHz at Beijing (Peking) Observatory since May 1981. A preliminary analysis was made. It can be seen from the data that the MMS-events have a variety of the fast activities such as the dispersed and isolated spikes, the clusters of the crowded spikes, the weak spikes superimposed on the noise background, and the phenomena of absorption. The marked differences from that observed with lower time resolution are presented. Using the data, a valuable statistical analysis was made. There are close correlations between MMS-events and hard X-ray bursts, and fast drifting bursts. The MMS events are highly dependent on the type of active regions and the magnetic field configuration. It seems to be crucial to find out the accurate positions on the active region where the MMS-events happen and to make co-operative observations at different bands during the special period when specific active regions appear on the solar disk

    GABA, progesterone and zona pellucida activation of PLA2 and regulation by MEK-ERK1/2 during acrosomal exocytosis in guinea pig spermatozoa

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    AbstractWe investigated whether GABA activates phospholipase A2 (PLA2) during acrosomal exocytosis, and if the MEK-ERK1/2 pathway modulates PLA2 activation initiated by GABA, progesterone or zona pellucida (ZP). In guinea pig spermatozoa prelabelled with [14C]arachidonic acid or [14C]choline chloride, GABA stimulated a decrease in phosphatidylcholine (PC), and release of arachidonic acid and lysoPC, during exocytosis. These lipid changes are indicative of PLA2 activation and appear essential for exocytosis since inclusion of aristolochic acid (a PLA2 inhibitor) abrogated them, along with exocytosis. GABA activation of PLA2 seems to be mediated, at least in part, by diacylglycerol (DAG) and protein kinase C since inclusion of the DAG kinase inhibitor R59022 enhanced PLA2 activity and exocytosis stimulated by GABA, whereas exposure to staurosporine decreased both. GABA-, progesterone- and ZP-induced release of arachidonic acid and exocytosis were prevented by U0126 and PD98059 (MEK inhibitors). Taken together, our results suggest that PLA2 plays a fundamental role in agonist-stimulated exocytosis and that MEK-ERK1/2 are involved in PLA2 regulation during this process

    DESIGN OF NOVEL CPW CROSS-FED ANTENNA

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    Abstract—A novel coplannar waveguide (CPW) cross-fed antenna which is wideband, high-gain and omnidirectional is proposed. After simulating the antenna model by CST MICROWAVE STUDIO R©, the results show that this antenna not only has compact size, but also can effectively broaden operating band, improve gain and remain omnidirectional. In addition, adjusting antenna elements ’ dimension and spacing can control the central frequency position of operating band and bandwidth. The simulated results of antenna surface currents can be used to explain the reason of antenna possessing broadband and omnidirectional high-gain characteristics. A CPW cross-fed antenna operating at 2.4GHz is designed and manufactured for measurement. The prototype is printed on a FR-4 epoxy resin board with 1mm thickness. The experimental results indicate that the operating band is 2.35–2.85GHz with reflection coefficient less than −10 dB (relative bandwidth 19.2%), and maximum gain in H-plane can achieve 5.2 dBi. Measured results well match the simulated ones. Moreover, the total antenna size is 187mm × 22.5mm (1.5λ × 0.18λ), which can make it suitable in WLAN systems. 1

    Polysaccharides from natural resource: ameliorate type 2 diabetes mellitus via regulation of oxidative stress network

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    Diabetes mellitus (DM) is a group of metabolic diseases characterized by hyperglycemia that can occur in children, adults, elderly people, and pregnant women. Oxidative stress is a significant adverse factor in the pathogenesis of DM, especially type 2 diabetes mellitus (T2DM), and metabolic syndrome. Natural polysaccharides are macromolecular compounds widely distributed in nature. Some polysaccharides derived from edible plants and microorganisms were reported as early as 10 years ago. However, the structural characterization of polysaccharides and their therapeutic mechanisms in diabetes are relatively shallow, limiting the application of polysaccharides. With further research, more natural polysaccharides have been reported to have antioxidant activity and therapeutic effects in diabetes, including plant polysaccharides, microbial polysaccharides, and polysaccharides from marine organisms and animals. Therefore, this paper summarizes the natural polysaccharides that have therapeutic potential for diabetes in the past 5 years, elucidating their pharmacological mechanisms and identified primary structures. It is expected to provide some reference for the application of polysaccharides, and provide a valuable resource for the development of new diabetic drugs

    Development and Characterization of Polymorphic Microsatellite Markers (SSRs) for an Endemic Plant, Pseudolarix amabilis (Nelson) Rehd. (Pinaceae)

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    Pseudolarix (Pinaceae) is a vulnerable (sensu IUCN) monotypic genus restricted to southeastern China. To better understand levels of genetic diversity, population structure and gene flow among populations of P. amabilis, we developed five compound SSR markers and ten novel polymorphic expressed sequence tags (EST) derived microsatellites. The results showed that all 15 loci were polymorphic with the number of alleles per locus ranging from two to seven. The expected and observed heterozygosities varied from 0.169 to 0.752, and 0.000 to 1.000, respectively. The inbreeding coefficient ranged from −0.833 to 1.000. These markers will contribute to research on genetic diversity and population genetic structure of P. amabilis, which in turn will contribute to the species conservation

    Long-term particulate matter modeling for health effect studies in California – Part 2: Concentrations and sources of ultrafine organic aerosols

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    Organic aerosol (OA) is a major constituent of ultrafine particulate matter (PM<sub>0. 1</sub>). Recent epidemiological studies have identified associations between PM<sub>0. 1</sub> OA and premature mortality and low birth weight. In this study, the source-oriented UCD/CIT model was used to simulate the concentrations and sources of primary organic aerosols (POA) and secondary organic aerosols (SOA) in PM<sub>0. 1</sub> in California for a 9-year (2000–2008) modeling period with 4 km horizontal resolution to provide more insights about PM<sub>0. 1</sub> OA for health effect studies. As a related quality control, predicted monthly average concentrations of fine particulate matter (PM<sub>2. 5</sub>) total organic carbon at six major urban sites had mean fractional bias of −0.31 to 0.19 and mean fractional errors of 0.4 to 0.59. The predicted ratio of PM<sub>2. 5</sub> SOA ∕ OA was lower than estimates derived from chemical mass balance (CMB) calculations by a factor of 2–3, which suggests the potential effects of processes such as POA volatility, additional SOA formation mechanism, and missing sources. OA in PM<sub>0. 1</sub>, the focus size fraction of this study, is dominated by POA. Wood smoke is found to be the single biggest source of PM<sub>0. 1</sub> OA in winter in California, while meat cooking, mobile emissions (gasoline and diesel engines), and other anthropogenic sources (mainly solvent usage and waste disposal) are the most important sources in summer. Biogenic emissions are predicted to be the largest PM<sub>0. 1</sub> SOA source, followed by mobile sources and other anthropogenic sources, but these rankings are sensitive to the SOA model used in the calculation. Air pollution control programs aiming to reduce the PM<sub>0. 1</sub> OA concentrations should consider controlling solvent usage, waste disposal, and mobile emissions in California, but these findings should be revisited after the latest science is incorporated into the SOA exposure calculations. The spatial distributions of SOA associated with different sources are not sensitive to the choice of SOA model, although the absolute amount of SOA can change significantly. Therefore, the spatial distributions of PM<sub>0. 1</sub> POA and SOA over the 9-year study period provide useful information for epidemiological studies to further investigate the associations with health outcomes

    Drivers of contaminant levels in surface water of China during 2000-2030:Relative importance for illustrative home and personal care product chemicals

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    Water pollution are among the most critical problems in China and emerging contaminants in surface water have attracted rising attentions in recent years. There is great interest in China's future environmental quality as the national government has committed to a major action plan to improve surface water quality. This study presents methodologies to rank the importance of socioeconomic and environmental drivers to the chemical concentration in surface water during 2000-2030. A case study is conducted on triclosan, a home and personal care product (HPCP) ingredient. Different economic and discharge flow scenarios are considered. Urbanization and wastewater treatment connection rates in rural and urban areas are collected or projected for 2000-2030 for counties across China. The estimated usage increases from ca. 86 to 340 t. However, emissions decreases from 76 to 52 t during 2000-2030 under a modelled Organisation for Economic Co-operation (OECD) economic scenario because of the urbanization, migration and development of wastewater treatment plants/facilities (WWTPs). The estimated national median concentration of triclosan ranges 1.5-8.2 ng/L during 2000-2030 for different scenarios. It peaks in 2009 under the OECD and three of the Intergovernmental Panel on Climate Change (IPCC), A2, B1 and B2 economic scenarios, but in 2025 under A1 economic scenario. Population distribution and surface water discharge flow rates are ranked as the top two drivers to triclosan levels in surface water over the 30 years. The development of urban WWTPs was the most important driver during 2000-2010 and the development of rural works is projected to be the most important in 2011-2030. Projections suggest discharges of ingredients in HPCPs - controlled by economic growth - should be balanced by the major expenditure programme on wastewater treatment in China

    Control of Intestinal Inflammation, Colitis-Associated Tumorigenesis, and Macrophage Polarization by Fibrinogen-Like Protein 2

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    Fibrinogen-like protein 2 (Fgl2) is critical for immune regulation in the inflammatory state. Elevated Fgl2 levels are observed in patients with inflammatory bowel disease (IBD), but little is known about its functional significance. In this study, we sought to investigate the role of Fgl2 in the development of intestinal inflammation and colitis-associated colorectal cancer (CAC). Here, we report that Fgl2 deficiency increased susceptibility to dextran sodium sulfate-induced colitis and CAC in a mouse model. During colitis development, the expression of the membrane-bound and secreted forms of Fgl2 (mFgl2 and sFgl2, respectively) in the colon were increased and predominantly expressed by colonic macrophages. In addition, using bone marrow chimeric mice, we determined that Fgl2 function in colitis is strictly related to its expression in the hematopoietic cells. Loss of Fgl2 induced the polarization of M1, but suppressed that of M2 both in vivo and in vitro, independent of intestinal inflammation. Thus, Fgl2 suppresses intestinal inflammation and CAC development through its role in macrophage polarization and may serve as a therapeutic target in inflammatory diseases, including IBD

    Integration of the metabolome and transcriptome reveals the metabolites and genes related to nutritional and medicinal value in Coriandrum sativum

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    Coriandrum sativum (Coriander) or Chinese parsley is a culinary herb with multiple medicinal effects, which is widely used in cooking and traditional medicine. It is enriched with essential oils and anti-oxidant compounds with unknown significance. To explore the untapped reservoir of Coriander, we studied the transcriptome and metabolic profiles from three developmental stages. Here, we identified 10 tyrosine metabolic pathway-related genes (TMPRGs), six porphyrins and chlorophyll metabolic pathway-related genes (PCMPRGs), and five Vitamin E metabolic pathway-related genes (VEMPRGs). These genes were associated with the early development of Coriander. Our analysis suggests that these pathways are involved in the production of critical phenolic metabolites. Furthermore, we constructed the interaction network between these pathway-related genes and transcription factors (TFs), which supported the regulatory pathways for phenolic metabolites. Interestingly, we identified several nutritional or medicinally relevant metabolites, including 59 phenols, two polyamines, 12 alkaloids, and one terpenoid. The higher concentrations of metabolites were from caffeic acid, agmatine, and its derivatives. We found higher levels of caffeic acid and agmatine at 30 days compared to 60 or 90 days. This study provides evidence to stimulate further investigation of the role of these metabolites in medicinal and nutritional research
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