Estimation of the refractive index of volcanic ash from satellite infrared sounder data

AbstractWe investigated the spectral refractive indices (RIs) of volcanic ash materials in the wavenumber range of 700–1100cm−1 using satellite infrared sounder measurements and radiative transfer calculations. The ash RIs of 10 ash clouds from eight volcanoes were evaluated (Bezymianny on 2 September 2012, Chaitén on 3 May 2008, Kelut on 14 February 2014, Kirishimayama on 27 January 2011, Kliuchevskoi on 30 June 2007 and 18 October 2013, Puyehue–Cordon Caulle on 5 June 2011, Sangeang-Api on 31 May 2014, and Sheveluch on 28 October 2010 and 18 September 2012). We elaborated on a dataset of volcanic ash measurements made by the Atmospheric Infrared Sounder (AIRS) onboard the Aqua satellite. The measured brightness temperatures in the ash cloud data revealed silicate absorption features at around 10μm. By applying atmospheric profiles from results of a global data assimilation system and using ash cloud properties (ash optical depth, effective radius, and ash cloud height) as parameters for radiative transfer calculations, least squares analyses for the observed and calculated brightness temperatures were conducted using AIRS channels in the wavenumber range of 700–1100cm−1, except for the O3 absorption channels in the range of 980–1070cm−1. Using the RIs for typical volcanic rocks in the ascending order of SiO2 content, basalt, andesite, and rhyolite, a mixture of basalt and rhyolite and a mixture of andesite and rhyolite for the ash material were considered. The volume fraction of the mixture was used as a retrieval parameter and as the ash cloud parameter. Using the estimated ash cloud parameters as fixed values, and under the assumption that the RI from the estimated volume fraction had some accuracy in the wavenumber ranges of 850–980cm−1 and 1070–1100cm−1, the RI imaginary part of each eruptive ash cloud captured by AIRS was then determined from iterative calculations at wavenumbers between 750cm−1 and 980cm−1. In the wavenumber range of 850–980cm−1, the observed brightness temperatures could be approximately simulated using the reported RIs from Pollack, Toon, and Khare (1973) for andesite, basalt, and rhyolite, and their combinations. Furthermore, some estimated RIs were consistent with the reported rock types of the volcanoes, which had been previously classified by compositional analyses in the literature. Our analysis also identified weak absorptions around 750–850cm−1, which could not be reproduced by the reported RIs. These weak absorptions were likely due to Si–O and/or Al–O vibrations, which have been proposed in reports from previous laboratory experiments for some silicate glass samples. Our results suggest that the detailed RI of volcanic ash can be determined from an analysis of satellite infrared sounder data. The RI of the ash material estimated from satellite infrared sounder data can be used to improve the ash retrieval algorithms of other satellite measurements. Furthermore, an RI retrieved by sounder measurements may provide diagnostic information regarding volcanic activity from comparisons with the ash RIs from past eruptions

imple syntheses of lespedamine and 5-bromo-N,N-dimethyltryptamine based on 1-hydroxyindole chemistry

金沢大学大学院自然科学研究科生理活性物質科

Unc93B1 Restricts Systemic Lethal Inflammation by Orchestrating Toll-like Receptor 7 and 9 Trafficking

SummaryToll-like receptor-7 (TLR7) and 9, innate immune sensors for microbial RNA or DNA, have been implicated in autoimmunity. Upon activation, TLR7 and 9 are transported from the endoplasmic reticulum (ER) to endolysosomes for nucleic acid sensing by an ER-resident protein, Unc93B1. Little is known, however, about a role for sensor transportation in controlling autoimmunity. TLR9 competes with TLR7 for Unc93B1-dependent trafficking and predominates over TLR7. TLR9 skewing is actively maintained by Unc93B1 and reversed to TLR7 if Unc93B1 loses preferential binding via a D34A mutation. We here demonstrate that mice harboring a D34A mutation showed TLR7-dependent, systemic lethal inflammation. CD4+ T cells showed marked differentiation toward T helper 1 (Th1) or Th17 cell subsets. B cell depletion abolished T cell differentiation and systemic inflammation. Thus, Unc93B1 controls homeostatic TLR7 activation by balancing TLR9 to TLR7 trafficking

Functions of mucosal associated invariant T cells in eye diseases

Mucosal-associated invariant T (MAIT) cells are a unique subset of T cells that recognizes metabolites derived from the vitamin B2 biosynthetic pathway. Since the identification of cognate antigens for MAIT cells, knowledge of the functions of MAIT cells in cancer, autoimmunity, and infectious diseases has been rapidly expanding. Recently, MAIT cells have been found to contribute to visual protection against autoimmunity in the eye. The protective functions of MAIT cells are induced by T-cell receptor (TCR)-mediated activation. However, the underlying mechanisms remain unclear. Thus, this mini-review aims to discuss our findings and the complexity of MAIT cell-mediated immune regulation in the eye

Cleavage of Toll-Like Receptor 9 Ectodomain Is Required for In Vivo Responses to Single Strand DNA

Mouse toll-like receptor 9 (TLR9) is an endosomal sensor for single-stranded DNA. TLR9 is transported from the endoplasmic reticulum to endolysosomes by a multiple transmembrane protein Unc93 homolog B1, and proteolytically cleaved at its ectodomain. The structure of TLR9 and its biochemical analyses have shown that the proteolytic cleavage of TLR9 ectodomain enables TLR9-dimerization and TLR9 activation. However, the requirement of TLR9 cleavage in vivo has not been studied. We here show that the 13 amino acids deletion at the cleavage site made TLR9 resistant to proteolytic cleavage. The deletion mutation in the Tlr9 gene impaired TLR9-dependent cytokine production in conventional dendritic cells from the mutant mice. Not only in vitro, in vivo production of inflammatory cytokines (TNF-α and IL-12p40), chemokine (CCR5/RANTES), and type I interferon (IFN-α) induced by administration of TLR9 ligand was also impaired. These results demonstrate that the TLR9 cleavage is required for TLR9 responses in vivo

Towards single particle imaging of human chromosomes at SACLA

Robinson I., Schwenke J., Yusuf M., et al. Towards single particle imaging of human chromosomes at SACLA. Journal of Physics B: Atomic, Molecular and Optical Physics, 48, 24, 244007. https://doi.org/10.1088/0953-4075/48/24/244007