577 research outputs found

    A comparison of filtration performance of triangular and circular cross-section fibre

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    Various filtering media, composed of different GSM of polyethylene terephthalate (PET) triangular and circular cross-section fibre nonwovens, have been selected to measure the filtration performance respectively. A middle-layer of polypropylene (PP) nonwoven material is added to form a three-layered sandwich composite PET/PP/PET filter. The fibre located in the upstream and downstream layers are triangular cross-section fibre, circular cross-section fibre and their mixture. The structure of materials including fibre fineness, thickness, pore size distribution and air permeability of webs has been studied in detail. The filtration efficiency and resistance of the filter materials are studied with NaCl aerosol particles in range of 0.3-3.0 µm at 32 L/min and 85 L/min flow rate. The results indicate that the filtration performance of triangular cross-section fibre is much superior than that of circular

    Study on Influence of Residual Magnetite in Panzhihua Ilmenite Flotation

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    AbstractThe main utilization mode of titano-magnetite was firstly separating titano-magnetite by low intensity magnetic separation, then concentrating ilmenite from magnetic separation tailings. Magnetic separation tailings mainly contained ilmenite, but there was still a small quantity of titano-magnetite. Magnetic agglomeration of titanomagnetite occured because of existentence of remanence and pre-flotation grinding. It was found that titanomagnetite presented more optimal floatability than ilmenite. Therefore some gangues wrapped by titano-magnetite went into the floatation concentrate. In a word, titano-magnetite had negative effect on ilmenite floatation by decreasing grade and recovery of concentrate and increasing reagent consumption. The pre-removal of residual titano-magnetite before cleaning ilmenite from magnetic separation tailings by floatation was essential

    Terahertz magnetic field induced coherent spin precession in YFeO3

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    We present the magnetic dipole transition at 0.299 THz excited by magnetic component of terahertz electromagnetic pulse in an antiferromagnetic YFeO3 crystal. The impulsive magnetic field of the terahertz pulse tilts the macroscopic magnetization, causing deviation from the equilibrium position, which is manifested by a sharp absorption at the frequency of the quasiferromagnetic mode of the crystal. The rotating coherent macroscopic magnetization radiates elliptically polarized emission at the frequency of the quasiferromagnetic resonance due to the dichroic absorption in the crystal

    Punicalagin alleviates brain injury and inflammatory responses, and regulates HO-1/Nrf-2/ARE signaling in rats after experimental intracerebral haemorrhage

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    Purpose: To investigate the effect of punicalagin, an ellagitannin present in pomegranates, on intracerebral haemorrhage (ICH)-induced inflammatory responses and oxidative stress, and also unravel the underlying mechanism(s) of action. Methods: Collagenase type IV (0.2 U) was used to induce ICH in adult male Sprague-Dawley rats. Punicalagin was given to the rats at doses of 25, 50, and 75 mg/kg body weight via oral gavage for 15 days before ICH induction. The animals were sacrificed 24h following induction of ICH, and their brains were excised immediately and used for analysis. Histological changes were determined with Haematoxylin and Eosin (H&E) staining. Permeability to blood-brain barrier (BBB) was determined by quantifying the extent of extravasation of Evan Blue (EB). Protein expressions of HO-1/Nrf-2/ARE and NF-κB signaling were assayed using immunoblotting and RT-PCR. Levels of reactive oxygen species (ROS) and serum levels of cytokines were also determined. Results: Punicalagin treatment reduced inflammatory cell infiltration and cell damage, improved brain tissue architecture and BBB integrity. The punicalagin treatment increased the activities of antioxidant enzymes, and enhanced antioxidant status via activation of Nrf-2/ARE/HO-1 signaling pathway (p < 0.05). The treatment upregulated the expressions of HO-1 to 174 %, relative to 127 % in ICH control rats. Furthermore, it enhanced NF-κB levels and reversed the ICH injury-induced upregulations of IL-6, IL-18 and IL-1β. Conclusion: These findings indicate that punicalagin exerts neuroprotective effect in rats after experimental ICH through regulation of theHO-1/Nrf-2/ARE signaling pathway. Thus, punicalagin has therapeutic potential for ICH. Keywords: Brain injury, Haemoxygenase-1, Intracerebral haemorrhage, Inflammatory responses, Nrf2/ARE signalling, Punicalagi

    Distinct mechanisms of decadal subsurface heat content variations in the eastern and western Indian Ocean modulated by tropical Pacific SST

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    Author Posting. © American Meteorological Society, 2018. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 31 (2018): 7751-7769, doi:10.1175/JCLI-D-18-0184.1.Decadal variability of the subsurface ocean heat content (OHC) in the Indian Ocean is investigated using a coupled climate model experiment, in which observed eastern tropical Pacific sea surface temperature (EPSST) anomalies are specified. This study intends to understand the contributions of external forcing relative to those of internal variability associated with EPSST, as well as the mechanisms by which the Pacific impacts Indian Ocean OHC. Internally generated variations associated with EPSST dominate decadal variations in the subsurface Indian Ocean. Consistent with ocean reanalyses, the coupled model reproduces a pronounced east–west dipole structure in the southern tropical Indian Ocean and discontinuities in westward-propagating signals in the central Indian Ocean around 100°E. This implies distinct mechanisms by which the Pacific impacts the eastern and western Indian Ocean on decadal time scales. Decadal variations of OHC in the eastern Indian Ocean are attributed to 1) western Pacific surface wind anomalies, which trigger oceanic Rossby waves propagating westward through the Indonesian Seas and influence Indonesian Throughflow transport, and 2) zonal wind anomalies over the central tropical Indian Ocean, which trigger eastward-propagating Kelvin waves. Decadal variations of OHC in the western Indian Ocean are linked to conditions in the Pacific via changes in the atmospheric Walker cell, which trigger anomalous wind stress curl and Ekman pumping in the central tropical Indian Ocean. Westward-propagating oceanic Rossby waves extend the influence of this anomalous Ekman pumping to the western Indian Ocean.This research was supported by the Independent Research and Development Program at WHOI to CCU, an NSF OCE PO grant (NSF OCE- 1242989) to Young-Oh Kwon, NOAA CP CVP grants (NA15OAR4310176 and NA17OAR4310255) to Hyodae Seo, and a research grant fromtheMinistry of Science and Technology of the People’s Republic of China to Tsinghua University (2017YFA0603902).2019-02-1

    Chromosomal DNA deletion confers phage resistance to Pseudomonas aeruginosa.

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    Bacteria develop a broad range of phage resistance mechanisms, such as prevention of phage adsorption and CRISPR/Cas system, to survive phage predation. In this study, Pseudomonas aeruginosa PA1 strain was infected with lytic phage PaP1, and phage-resistant mutants were selected. A high percentage (~30%) of these mutants displayed red pigmentation phenotype (Red mutant). Through comparative genomic analysis, one Red mutant PA1r was found to have a 219.6 kb genomic fragment deletion, which contains two key genes hmgA and galU related to the observed phenotypes. Deletion of hmgA resulted in the accumulation of a red compound homogentisic acid; while A galU mutant is devoid of O-antigen, which is required for phage adsorption. Intriguingly, while the loss of galU conferred phage resistance, it significantly attenuated PA1r in a mouse infection experiment. Our study revealed a novel phage resistance mechanism via chromosomal DNA deletion in P. aeruginosa
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