Control of the water fugacity at high pressures and temperatures: Applications to the incorporation mechanisms of water in olivine

a b s t r a c t A new method is developed to control water fugacity at a fixed pressure and temperature. We use two divariant phase assemblages (clinohumite-periclase-forsterite and brucite-periclase) in the MgOSiO 2 -H 2 O system and the chemical reactions among co-existing phases buffer the water fugacity. In order to avoid a reaction between the water fugacity buffer and the specimen, a double-capsule assemblage was designed such that the water fugacity buffer was separated from the specimen by an inner metal jacket permeable to hydrogen and impermeable to other components. This method was applied to investigate the incorporation mechanisms of water in single crystals of San Carlos olivine as a function of water fugacity at 5 GPa and 1273 K. The chemical environment of the olivine crystal was controlled by the water fugacity buffer, the Ni-NiO oxygen fugacity buffer, and the olivine-orthopyroxene silica activity buffer. The establishment of chemical equilibrium was demonstrated by the presence of all relevant phases in the buffering reactions. The effect of water fugacity on water concentration in olivine was investigated using Fourier transform infrared (FTIR) spectroscopy with a polarized light. The total water concentration is nearly linearly dependent on water fugacity, indicating that the dominant incorporation mechanism of water in olivine involves two hydrogen atoms substituted in a Mg-site vacancy. The proposed method of the water fugacity buffer can be applicable to investigate the role of water in various important properties including water solubility and partitioning between mantle minerals, rheological properties, electrical conductivity, as well as solidus temperatures

Ⅴ. Application and other cases

Editor : Tazaki, Kazue |田崎, 和

Label-free observation of tissues by high-speed stimulated Raman spectral microscopy and independent component analysis

SPIE BiOS, 2013, San Francisco, California, United StatesYasuyuki Ozeki, Yoichi Otsuka, Shuya Sato, Hiroyuki Hashimoto, Wataru Umemura, Kazuhiko Sumimura, Norihiko Nishizawa, Kiichi Fukui, Kazuyoshi Itoh, "Label-free observation of tissues by high-speed stimulated Raman spectral microscopy and independent component analysis," Proc. SPIE 8588, Multiphoton Microscopy in the Biomedical Sciences XIII, 858806 (22 February 2013); https://doi.org/10.1117/12.200277

The simultaneous determination of silicic, boric and carbonic acids in natural water via ion-exclusion chromatography with a charged aerosol detector

The simple and simultaneous determination of silicic, boric and carbonic acids was made using ion-exclusion chromatography (IEC) and a Corona™ charged aerosol detector (C-CAD). Silicic and boric acids were separated by the column packed with a weakly acidic cation-exchange resin in H+-form and ultra-pure water eluent, and the detector responses were improved by the addition of acetonitrile to eluent. Under the optimized conditions, the simultaneous determination of weak inorganic acids, except for carbonic acid, was successfully performed. When the conversion column packed with a strong acidic cation-exchange resin in Na+- or K+-form was inserted between the separation column and the detector, weak inorganic acids including carbonic acid could be detected by the C-CAD. The calibration curves were linear in the range of 0.5–10 mg·L−1 as Si for silicic acid (r2 = 0.996), 10–100 mg·L−1 as B for boric acid (r2 = 0.998) and 1.3–21 mg·L−1 as C for carbonic acid (r2 = 0.993). The detection limits based on three times the standard deviation were 0.03 mg·L−1 as Si for silicic acid, 0.40 mg·L−1 as B for boric acid and 0.08 mg·L−1 as C for carbonic acid. This method was applicable to river, hot spring and drinking water

Plasma substance p levels in patients with persistent cough.

Background: Substance P (SP) is involved in the pathogenesis of cough in animal models. However, few studies in humans have been reported and the roles of SP in clinical cough remain obscure. Objectives: To clarify the relevance of plasma levels of SP in patients with persistent cough. Methods: We studied 82 patients with cough persisting for at least 3 weeks and 15 healthy controls. Patients were classified as having asthmatic cough (cough-variant asthma and cough-predominant asthma; n = 61) or nonasthmatic cough (n = 21; postinfectious cough, n = 6; gastroesophageal reflux disease, n = 5; idiopathic cough, n = 5, and others, n = 5). Correlations were evaluated between plasma SP levels as measured with ELISA and methacholine airway hyperresponsiveness (airway sensitivity and airway reactivity), capsaicin cough sensitivity, sputum eosinophil and neutrophil counts, and pulmonary function. Results: Plasma SP levels were significantly elevated in patients with both asthmatic and nonasthmatic cough compared with controls [31.1 pg/ml (range 18.0-52.2) and 30.0 pg/ml (range 15.1-50.3) vs. 15.4 pg/ml (range 11.3-23.7); p = 0.003 and p = 0.038, respectively] but did not differ between the two patient groups (p = 0.90). Plasma SP levels correlated with airway sensitivity (threshold dose of methacholine) in the patients with asthmatic cough (r = -0.37, p = 0.005) but not with airway reactivity, cough sensitivity, FEV(1) values, or sputum eosinophil and neutrophil counts in either group. Conclusions: Increased levels of SP in plasma are associated with persistent cough in humans and might be related to airway sensitivity in asthmatic cough

High Serum Advanced Glycation End Products Are Associated with Decreased Insulin Secretion in Patients with Type 2 Diabetes: A Brief Report

Advanced glycation end products (AGEs) are important in the pathophysiology of type 2 diabetes mellitus (T2DM). They directly cause insulin secretory defects in animal and cell culture models and may promote insulin resistance in nondiabetic subjects. We have developed a highly sensitive liquid chromatography-tandem mass spectrometry method for measuring AGEs in human serum. Here, we use this method to investigate the relationship between AGEs and insulin secretion and resistance in patients with T2DM. Methods. Our study involved 15 participants with T2DM not on medication and 20 nondiabetic healthy participants. We measured the AGE carboxyethyllysine (CEL), carboxymethyllysine (CML), and methyl-glyoxal-hydro-imidazolone (MG-H1). Plasma glucose and insulin were measured in these participants during a meal tolerance test, and the glucose disposal rate was measured during a euglycemic-hyperinsulinemic clamp. Results. CML and CEL levels were significantly higher in T2DM than non-DM participants. CML showed a significant negative correlation with insulin secretion, HOMA-%B, and a significant positive correlation with the insulin sensitivity index in T2DM participants. There was no correlation between any of the AGEs measured and glucose disposal rate. Conclusions. These results suggest that AGE might play a role in the development or prediction of insulin secretory defects in type 2 diabetes

Receptor for Activated Protein Kinase C: Requirement for Efficient MicroRNA Function and Reduced Expression in Hepatocellular Carcinoma

MicroRNAs (miRNAs) are important regulators of gene expression that control physiological and pathological processes. A global reduction in miRNA abundance and function is a general trait of human cancers, playing a causal role in the transformed phenotype. Here, we sought to newly identify genes involved in the regulation of miRNA function by performing a genetic screen using reporter constructs that measure miRNA function and retrovirus-based random gene disruption. Of the six genes identified, RACK1, which encodes “receptor for activated protein kinase C” (RACK1), was confirmed to be necessary for full miRNA function. RACK1 binds to KH-type splicing regulatory protein (KSRP), a member of the Dicer complex, and is required for the recruitment of mature miRNAs to the RNA-induced silencing complex (RISC). In addition, RACK1 expression was frequently found to be reduced in hepatocellular carcinoma. These findings suggest the involvement of RACK1 in miRNA function and indicate that reduced miRNA function, due to decreased expression of RACK1, may have pathologically relevant roles in liver cancers