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Electrochemical and spectroscopic study of interfacial interactions between chalcopyrite and typical flotation process reagents 下载免费PDF全文
Gustavo Urbano Isabel Lázaro Israel Rodríguez Juan Luis Reyes Roxana Larios Roel Cruz 《矿物冶金与材料学报》2016,23(2):127-136
Comparative voltammetry and differential double-layer capacitance studies were performed to evaluate interfacial interactions between chalcopyrite (CuFeS2) and n-isopropyl xanthate (X) in the presence of ammonium bisulfite/39wt% SO2 and caustic starch at different pH values. Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, contact angle measurements, and microflotation tests were used to establish the type and extent of xanthate adsorption as well as the species involved under different mineral surface conditions in this study. The results demonstrate that the species that favor a greater hydrophobicity of chalcopyrite are primarily CuX and S0, whereas oxides and hydroxides of Cu and Fe as well as an excess of starch decrease the hydrophobicity. A conditioning of the mineral surface with ammonium bisulfite/39wt% SO2 at pH 6 promotes the activation of surface and enhances the xanthate adsorption. However, this effect is diminished at pH ≥ 8, when an excess of starch is added during the preconditioning step. 相似文献
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Anna Shteingauz Neta Ilan Israel Vlodavsky 《Cellular and molecular life sciences : CMLS》2014,71(22):4457-4470
Heparanase activity plays a decisive role in cell dissemination associated with cancer metastasis. Cellular uptake of heparanase is considered a pre-requisite for the delivery of latent 65-kDa heparanase to lysosomes and its subsequent proteolytic processing and activation into 8- and 50-kDa protein subunits by cathepsin L. Heparan sulfate proteoglycans, and particularly syndecan, are instrumental for heparanase uptake and activation, through a process that has been shown to occur independent of rafts. Nevertheless, the molecular mechanism underlying syndecan-mediated internalization outside of rafts is unclear. Here, we examined the role of syndecan-1 cytoplasmic domain in heparanase processing, utilizing deletion constructs lacking the entire cytoplasmic domain (Delta), the conserved (C1 or C2), or variable (V) regions. Heparanase processing was markedly increased following syndecan-1 over-expression; in contrast, heparanase was retained at the cell membrane and its processing was impaired in cells over-expressing syndecan-1 deleted for the entire cytoplasmic tail. We have next revealed that conserved domain 2 (C2) and variable (V) regions of syndecan-1 cytoplasmic tail mediate heparanase processing. Furthermore, we found that syntenin, known to interact with syndecan C2 domain, and α actinin are essential for heparanase processing. 相似文献
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A 20-fold, diet-induced increase in liver proline does not result in an increased accumulation of hydroxyproline following chronic carbon tetrachloride administration. 相似文献
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The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens probe 总被引:1,自引:0,他引:1
Niemann HB Atreya SK Bauer SJ Carignan GR Demick JE Frost RL Gautier D Haberman JA Harpold DN Hunten DM Israel G Lunine JI Kasprzak WT Owen TC Paulkovich M Raulin F Raaen E Way SH 《Nature》2005,438(7069):779-784
Saturn's largest moon, Titan, remains an enigma, explored only by remote sensing from Earth, and by the Voyager and Cassini spacecraft. The most puzzling aspects include the origin of the molecular nitrogen and methane in its atmosphere, and the mechanism(s) by which methane is maintained in the face of rapid destruction by photolysis. The Huygens probe, launched from the Cassini spacecraft, has made the first direct observations of the satellite's surface and lower atmosphere. Here we report direct atmospheric measurements from the Gas Chromatograph Mass Spectrometer (GCMS), including altitude profiles of the constituents, isotopic ratios and trace species (including organic compounds). The primary constituents were confirmed to be nitrogen and methane. Noble gases other than argon were not detected. The argon includes primordial 36Ar, and the radiogenic isotope 40Ar, providing an important constraint on the outgassing history of Titan. Trace organic species, including cyanogen and ethane, were found in surface measurements. 相似文献
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TNF-mediated inflammatory skin disease in mice with epidermis-specific deletion of IKK2 总被引:31,自引:0,他引:31
Pasparakis M Courtois G Hafner M Schmidt-Supprian M Nenci A Toksoy A Krampert M Goebeler M Gillitzer R Israel A Krieg T Rajewsky K Haase I 《Nature》2002,417(6891):861-866
The I kappa B kinase (IKK), consisting of the IKK1 and IKK2 catalytic subunits and the NEMO (also known as IKK gamma) regulatory subunit, phosphorylates I kappa B proteins, targeting them for degradation and thus inducing activation of NF-kappa B (reviewed in refs 1, 2). IKK2 and NEMO are necessary for NF-kappa B activation through pro-inflammatory signals. IKK1 seems to be dispensable for this function but controls epidermal differentiation independently of NF-kappa B. Previous studies suggested that NF-kappa B has a function in the growth regulation of epidermal keratinocytes. Mice lacking RelB or I kappa B alpha, as well as both mice and humans with heterozygous NEMO mutations, develop skin lesions. However, the function of NF-kappa B in the epidermis remains unclear. Here we used Cre/loxP-mediated gene targeting to investigate the function of IKK2 specifically in epidermal keratinocytes. IKK2 deficiency inhibits NF-kappa B activation, but does not lead to cell-autonomous hyperproliferation or impaired differentiation of keratinocytes. Mice with epidermis-specific deletion of IKK2 develop a severe inflammatory skin disease, which is caused by a tumour necrosis factor-mediated, alpha beta T-cell-independent inflammatory response that develops in the skin shortly after birth. Our results suggest that the critical function of IKK2-mediated NF-kappa B activity in epidermal keratinocytes is to regulate mechanisms that maintain the immune homeostasis of the skin. 相似文献
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Burrows DN Kennea JA Ghisellini G Mangano V Zhang B Page KL Eracleous M Romano P Sakamoto T Falcone AD Osborne JP Campana S Beardmore AP Breeveld AA Chester MM Corbet R Covino S Cummings JR D'Avanzo P D'Elia V Esposito P Evans PA Fugazza D Gelbord JM Hiroi K Holland ST Huang KY Im M Israel G Jeon Y Jeon YB Jun HD Kawai N Kim JH Krimm HA Marshall FE P Mészáros Negoro H Omodei N Park WK Perkins JS Sugizaki M Sung HI Tagliaferri G Troja E Ueda Y Urata Y Usui R Antonelli LA Barthelmy SD Cusumano G 《Nature》2011,476(7361):421-424
Supermassive black holes have powerful gravitational fields with strong gradients that can destroy stars that get too close, producing a bright flare in ultraviolet and X-ray spectral regions from stellar debris that forms an accretion disk around the black hole. The aftermath of this process may have been seen several times over the past two decades in the form of sparsely sampled, slowly fading emission from distant galaxies, but the onset of the stellar disruption event has not hitherto been observed. Here we report observations of a bright X-ray flare from the extragalactic transient Swift J164449.3+573451. This source increased in brightness in the X-ray band by a factor of at least 10,000 since 1990 and by a factor of at least 100 since early 2010. We conclude that we have captured the onset of relativistic jet activity from a supermassive black hole. A companion paper comes to similar conclusions on the basis of radio observations. This event is probably due to the tidal disruption of a star falling into a supermassive black hole, but the detailed behaviour differs from current theoretical models of such events. 相似文献
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Somatic coding mutations in human induced pluripotent stem cells 总被引:2,自引:0,他引:2
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Regulation of flowering time by FVE, a retinoblastoma-associated protein 总被引:25,自引:0,他引:25
Ausín I Alonso-Blanco C Jarillo JA Ruiz-García L Martínez-Zapater JM 《Nature genetics》2004,36(2):162-166