232 research outputs found

    The mean composition of ocean ridge basalts

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    The mean composition of mid-ocean ridge basalts (MORB) is determined using a global data set of major ele- ments, trace elements, and isotopes compiled from new and previously published data. A global catalog of 771 ridge segments, including their mean depth, length, and spreading rate enables calculation of average compositions for each segment. Segment averages allow weighting by segment length and spreading rate and reduce the bias introduced by uneven sampling. A bootstrapping statistical technique provides rigorous error estimates. Based on the characteristics of the data, we suggest a revised nomenclature for MORB. “ALL MORB” is the total composition of the crust apart from back-arc basins, N-MORB the most likely basalt composition encountered along the ridge >500 km from hot spots, and D-MORB the depleted end-member. ALL MORB and N-MORB are substantially more enriched than early estimates of normal ridge basalts. The mean composition of back-arc spreading centers requires higher extents of melting and greater concentrations of fluid-mobile elements, reflecting the influence of water on back-arc petro- genesis. The average data permit a re-evaluation of several problems of global geochemistry. The K/U ratio reported here (12,340 ` 840) is in accord with previous estimates, much lower than the estimate of Arevalo et al. (2009). The low Sm/Nd and 143Nd/144Nd ratio of ALL MORB and N-MORB provide constraints on the hypothesis that Earth has a non-chondritic primitive mantle. Either Earth is chondritic in Sm/Nd and the hypothesis is incorrect or MORB preferentially sample an enriched reservoir, requiring a large depleted reservoir in the deep mantle.Earth and Planetary Science

    Modeling and Experimental Study on Characterization of Micromachined Thermal Gas Inertial Sensors

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    Micromachined thermal gas inertial sensors based on heat convection are novel devices that compared with conventional micromachined inertial sensors offer the advantages of simple structures, easy fabrication, high shock resistance and good reliability by virtue of using a gaseous medium instead of a mechanical proof mass as key moving and sensing elements. This paper presents an analytical modeling for a micromachined thermal gas gyroscope integrated with signal conditioning. A simplified spring-damping model is utilized to characterize the behavior of the sensor. The model relies on the use of the fluid mechanics and heat transfer fundamentals and is validated using experimental data obtained from a test-device and simulation. Furthermore, the nonideal issues of the sensor are addressed from both the theoretical and experimental points of view. The nonlinear behavior demonstrated in experimental measurements is analyzed based on the model. It is concluded that the sources of nonlinearity are mainly attributable to the variable stiffness of the sensor system and the structural asymmetry due to nonideal fabrication

    Transcriptome Analysis on Maternal Separation Rats With Depression-Related Manifestations Ameliorated by Electroacupuncture

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    Maternal separation (MS), a stressful event in early life, has been linked to neuropsychiatric disorders later in life, especially depression. In this study we investigated whether treatment with electroacupuncture (EA) could ameliorate depression-related manifestations in adult animals that had adverse early life experiences. We demonstrated depression-like behavior deficiencies in a sucrose preference test and a forced swimming test in a rat model with neonatal MS. Repeated EA treatment at the acupoints Baihui (GV20) and Yintang (GV29) during adulthood was shown to be remarkably attenuated above behavioral deficits. Using unbiased genome-wide RNA sequencing to investigate alterations in the transcriptome of the prefrontal cortex (PFC), we explored the altered gene sets involved in circadian rhythm and neurotransmitter transporter activity in MS rats, and their expression tended to be reversed after EA treatment. In addition, we analyzed the interaction network of differentiated lncRNA– or circRNA–miRNA–mRNA by using the principle of competitive endogenous RNA (ceRNA). These results suggest that EA at GV20 and GV29 ameliorates depression-related manifestations by regulating the expression of multiple genes

    Does a radio jet drive the massive multi-phase outflow in the ultra-luminous infrared galaxy IRAS 10565+2448?

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    We present new upgraded Giant Metrewave Radio Telescope (uGMRT) HI 21-cm observations of the ultra-luminous infrared galaxy IRAS 10565+2448, previously reported to show blueshifted, broad, and shallow HI absorption indicating an outflow. Our higher spatial resolution observations have localised this blueshifted outflow, which is \sim 1.36 kpc southwest of the radio centre and has a blueshifted velocity of 148kms1\sim 148\,\rm km\,s^{-1} and a full width at half maximum (FWHM) of 581kms1\sim 581\,\rm km\,s^{-1}. The spatial extent and kinematic properties of the HI outflow are consistent with the previously detected cold molecular outflows in IRAS 10565+2448, suggesting that they likely have the same driving mechanism and are tracing the same outflow. By combining the multi-phase gas observations, we estimate a total outflowing mass rate of at least 140Myr1140\, \rm M_\odot \,yr^{-1} and a total energy loss rate of at least 8.9×1042ergs18.9\times10^{42}\,\rm erg\,s^{-1}, where the contribution from the ionised outflow is negligible, emphasising the importance of including both cold neutral and molecular gas when quantifying the impact of outflows. We present evidence of the presence of a radio jet and argue that this may play a role in driving the observed outflows. The modest radio luminosity L1.4GHzL_{\rm1.4GHz} 1.3×1023WHz1\sim1.3\times10^{23}\,{\rm W\,Hz^{-1}} of the jet in IRAS 10565+2448 implies that the jet contribution to driving outflows should not be ignored in low radio luminosity AGN.Comment: 12 pages, 9 figures, accepted for publication in MNRA

    Use of Chlorella for the Treatment of the Soft-shelled Turtle Processing Wastewater

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    Abstract: The capability of Chlorella vulgaris to remove nitrogen in the form of ammonium ions from the softshelled turtle processing wastewater in a local agricultural products limited company (in Hangzhou, China) was studied. The soft-shelled turtle processing wastewater was found to include high concentrations of nitrogen (107.63±4.84 mg/L) in the form of ammonium (NH 4 + ) with the small amounts of nitrite (0.32±0.04 mg/L on annual average) at pH 6.7 and to be suitable for growing Chlorella vulgaris. When Chlorella vulgaris was cultivated in a batch mode, a majority of the nitrogen concentration was dramatically removed after a lag-phase period. The total biomass weight gained during the entire cultivation period balanced out well with the nitrogen removed from the culture medium. These results indicate that Chlorella vulgaris has potential to remove nitrogen (i.e., ammonium ion) and nitrite at a reasonable uptake rate from wastewater while being cultivated using the soft-shelled turtle processing wastewater

    Fenton reagent reduces the level of arsenic in paddy rice grain

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    Hydroponic and pot experiments were conducted to examine the effects of Fenton reagent on paddy rice plant growing in arsenic-contaminated soils. Fenton reagent significantly reduced arsenic phytotoxicity, uptake by the plants and accumulation in rice grain. This is attributed to oxidation of As3+ to As5+ by hydroxyl radicals and immobilization of arsenate by reacting with precipitating Fe3+ to form practically insoluble compounds. Although this process enhanced the formation of Fe-enriched coatings on root surface, it appears that root plaque had limited effects on inhibiting As uptake since most of the young roots were not covered by iron plaque. It is more likely that As immobilization in the bulk soils play a major role in reducing As flux towards rhizosphere. The findings have implications for understanding As behavior in paddy field receiving rainwater-borne hydrogen peroxide and developing cost-effective techniques for reducing As level in rice grain produced from As-contaminated soil

    SCARB2/LIMP-2 Regulates IFN Production of Plasmacytoid Dendritic Cells by Mediating Endosomal Translocation of TLR9 and Nuclear Translocation of IRF7

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    Scavenger receptor class B, member 2 (SCARB2) is essential for endosome biogenesis and reorganization and serves as a receptor for both β-glucocerebrosidase and enterovirus 71. However, little is known about its function in innate immune cells. In this study, we show that, among human peripheral blood cells, SCARB2 is most highly expressed in plasmacytoid dendritic cells (pDCs), and its expression is further upregulated by CpG oligodeoxynucleotide stimulation. Knockdown of SCARB2 in pDC cell line GEN2.2 dramatically reduces CpG-induced type I IFN production. Detailed studies reveal that SCARB2 localizes in late endosome/lysosome of pDCs, and knockdown of SCARB2 does not affect CpG oligodeoxynucleotide uptake but results in the retention of TLR9 in the endoplasmic reticulum and an impaired nuclear translocation of IFN regulatory factor 7. The IFN-I production by TLR7 ligand stimulation is also impaired by SCARB2 knockdown. However, SCARB2 is not essential for influenza virus or HSV-induced IFN-I production. These findings suggest that SCARB2 regulates TLR9-dependent IFN-I production of pDCs by mediating endosomal translocation of TLR9 and nuclear translocation of IFN regulatory factor 7
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