Characterization of acidic property of sulfo-group functionalized microporous and mesoporous silica by adsorption microcalorimetry

Sulfo-group functionalized microporous and mesoporous silica based-on a MCM-41 framework which showed solid acid property were synthesized and characterized by adsorption microcalorimetry. Both the sulfo-functionalized microporous and mesoporous silica (Micro-SO₃H and Meso-SO₃H) were prepared by the oxidation of thiol group (–SH) included mesoporous silica which was obtained through the hydrolysis and co-condensation of tetramethoxysilane (TMOS) and mercaptopropyl trimethoxysilane (MPTMS). The samples have an ordered two-dimensional hexagonal pore array similar to that of MCM-41 as depicted from the XRD patterns. Nitrogen adsorption also shows that both microporous and mesoporous silica have pore characteristics similar to MCM-41, i.e. high surface area and high pore volume. However, pore regularity, surface area and pore volume decreased as the MPTMS loading increased. Solid-state ²⁹Si NMR indicated that the sulfo groups were successfully incorporated into both microporous and mesoporous silica frameworks. This sulfo-functionalized porous silica have high NH₃ uptakes and high differential heats of NH₃ adsorption, suggesting the presence of strong acidic sulfo groups on the silica surface. Acid catalyses of the samples were characterized by the isomerization reaction of but-1-ene to cis, trans-but-2-ene.     

Compact ellipsometer employing a static polarimeter module with arrayed polarizer and wave-plate elements

A portable ellipsometer with a compact static polarimeter using an arrayed polarizer, an arrayed wave plate, and a CCD image sensor is developed. A high level of repeatability at a measurement speed of 0.3 s is demonstrated by measurement of SiO(2) films ranging from 2 to 300 nm in thickness deposited on an Si wafer. There is the potential to realize an ultracompact ellipsometer module by integrating the optical source and receiver, suitable for deployment in a variety of manufacturing equipment and measurement instruments.     

Thermodynamic properties of neptunium nitride: a first principles study

The thermal and mechanical properties of neptunium nitride (NpN) were investigated by first principles calculations. From the Helmholtz free energy equilibrium lattice constants, thermal expansion coefficients, bulk moduli and specific heat capacities were calculated for temperatures up to 1500 K. The electronic specific heat capacity was also calculated from the electronic density of states at the Fermi energy. The obtained specific heat capacity reproduced the experimental data well. It was thus clarified that the specific heat capacity of NpN consists of the lattice and electronic specific heat capacities and the contribution of the lattice dilatation to the specific heat capacity.     

Sensing of oligopeptides using localized surface plasmon resonances combined with Surface-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Gold nanorods were fixed on an ITO plate and used for the spectroscopic sensing and Surface-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (SALDI-MS) of oligopeptides (angiotensin I). The longitudinal surface plasmon bands of the gold nanorods responded to the 10(-10) M angiotensin solution that was cast on the ITO plate. The SALDI-MS measurements had an ultra-high sensitivity to the angiotensin on the ITO plate. A very small surface density (5 × 10(-19) mol cm(-2)) of angiotensin could be detected at m/z = 1297 with a good signal/noise ratio (S/N = 11). The ITO plate, which was modified with gold nanorods, was found to be effective in collecting angiotensin molecules adjacent to the gold nanorods, and the SALDI processes that were induced by the photoabsorption of the gold nanorods efficiently contributed to the desorption and ionization of the angiotensin.     

Preparation of nitrogen-doped porous carbon by ammonia gas treatment and the effects of N-doping on water adsorption

Nitrogen-doped porous carbons (N-RFCC) were prepared by NH₃N₂ mixture gas treatment at high temperature during the carbonization process on resorcinol–formaldehyde cryogels. To show the role of N-doping on the adsorption behavior we carried out water adsorption, and it was found that the amount of water adsorbed is directly related to the nitrogen content over the low pressure region (P/P₀ < 0.3). Applying the theoretical water adsorption model, Horikawa–Do (HD) model, to the adsorption isotherms of N-RFCCs, we could analyze the effects of nitrogen-doping on the adsorption mechanism. Although the concentration of functional groups of N-RFCC is almost equal to that of the non-doped RFCC, which was measured by Boehm titration method, the water adsorbed amounts of N-RFCCs over the low pressure region were larger. This is due to part of the doped nitrogen atoms act as functional groups, contributing to the total concentration of functional groups. The saturated concentrations depend on the packing fraction of water molecules, which in turn depends on the pore size. The packing fractions of N-RFCCs are larger than those of RFCCs, and this could be attributed to the high affinity between water clusters and N-doped surfaces, resulting in a reduced hydrophobicity of the surface.     

Pemafibrate Prevents Retinal Dysfunction in a Mouse Model of Unilateral Common Carotid Artery Occlusion

Cardiovascular diseases lead to retinal ischemia, one of the leading causes of blindness. Retinal ischemia triggers pathological retinal glial responses and functional deficits. Therefore, maintaining retinal neuronal activities and modulating pathological gliosis may prevent loss of vision. Previously, pemafibrate, a selective peroxisome proliferator-activated receptor alpha modulator, was nominated as a promising drug in retinal ischemia. However, a protective role of pemafibrate remains untouched in cardiovascular diseases-mediated retinal ischemia. Therefore, we aimed to unravel systemic and retinal alterations by treating pemafibrate in a new murine model of retinal ischemia caused by cardiovascular diseases. Adult C57BL/6 mice were orally administered pemafibrate (0.5 mg/kg) for 4 days, followed by unilateral common carotid artery occlusion (UCCAO). After UCCAO, pemafibrate was continuously supplied to mice until the end of experiments. Retinal function (a-and b-waves and the oscillatory potentials) was measured using electroretinography on day 5 and 12 after UCCAO. Moreover, the retina, liver, and serum were subjected to qPCR, immunohistochemistry, or ELISA analysis. We found that pemafibrate enhanced liver function, elevated serum levels of fibroblast growth factor 21 (FGF21), one of the neuroprotective molecules in the eye, and protected against UCCAO-induced retinal dysfunction, observed with modulation of retinal gliosis and preservation of oscillatory potentials. Our current data suggest a promising pemafibrate therapy for the suppression of retinal dysfunction in cardiovascular diseases.     

Characteristics of ammonia permeation through porous silica membranes

A sol–gel method was applied for the preparation of silica membranes with different average pore sizes. Ammonia (NH₃) permeation/separation characteristics of the silica membranes were examined in a wide temperature range (50–400°C) by measurement of both single and binary component separation. The order of gas permeance through the silica membranes, which was independent of membrane average pore size, was as follows: He > H₂ > NH₃ > N₂. These results suggest that, for permeation through silica membranes, the molecular size of NH₃ is larger than that of H₂, despite previous reports that the kinetic diameter of NH₃ is smaller than that of H₂. At high temperatures, there was no effect of NH₃ adsorption on H₂ permeation characteristics, and silica membranes were highly stable in NH₃ at 400°C (i.e., gas permeance remained unchanged). On the other hand, at 50°C NH₃ molecules adsorbed on the silica improved NH₃‐permselectivity by blocking permeation of H₂ molecules without decreasing NH₃ permeance. The maximal NH₃/H₂ permeance ratio obtained during binary component separation was ～30 with an NH₃ permeance of ～10^?7 mol m^?2 s^?1 Pa^?1 at an H₂ permeation activation energy of ～6 kJ mol^?1. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

COMPARISON OF PAHS,NITRO-PAHS AND OXY-PAHS ASSOCIATED WITH AIRBORNE PARTICULATE MATTER AT ROADSIDE AND URBAN BACKGROUND SITES IN DOWNTOWN TOKYO,JAPAN

Atmospheric polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs and oxy-PAHs are emitted from primary sources. Some nitro-PAHs and oxy-PAHs can also arise from secondary formation in the atmosphere. To assess the relative importance of these sources, the polycyclic aromatic compound (PAC) concentrations were determined at a roadside (Roadside site) and on a rooftop (Urban Background site) in downtown Tokyo Japan. The concentrations of PAHs, 1-nitropyrene and oxy-PAHs at the Roadside site were higher than those at the Urban Background site, while 2-nitrofluoranthene levels were the same at both sites. However, the mean ratios of concentrations at the Urban Background site to the Roadside site were in the order 1,8-naphthalic anhydride>9,10-anthraquinone>PAHs or 1-nitropyrene or acenaphthenequinone or benzanthrone. This suggests that in addition to vehicle emissions, a considerable fraction of some of the oxy-PAHs studied originates from another source, which might be secondary formation by atmospheric PAH degradation, and this contribution varied among the oxy-PAHs.     

Gas permeation properties for organosilica membranes with different Si/C ratios and evaluation of microporous structures

Organosilica membranes were fabricated using bridged organoalkoxysilanes (bis(triethoxysilyl)methane (BTESM), bis(triethoxysilyl)ethane (BTESE), bis(triethoxysilyl)propane (BTESP), bis(trimethoxysilyl)hexane (BTMSH), bis(triethoxysilyl)benzene (BTESB), and bis(triethoxysilyl)octane (BTESO)) to produce highly permeable molecular sieving membranes. The effect of the organoalkoxysilanes on network pore size and microporous structure was evaluated by examining the molecular size and temperature dependence of gas permeance across a wide range of temperatures. Organosilica membranes showed H₂/N₂ and H₂/CH₄ permeance ratios that ranged from 10 to 150, corresponding to network pore size, and both H₂ selectivity decreased with an increase in the carbon number between 2 Si atoms. Organosilica membranes showed activated diffusion for He and H₂, and a slope of temperature dependence that increased approximate to the increase in the carbon number between 2 Si atoms. The relationship between activation energy and He/H₂ permeance ratio for SiO₂ and organosilica membranes suggested that the molecular sieving can dominate He and H₂ permeation properties via the rigid microporous structure, which was constructed by BTESM and BTESE. With increased in the carbon concentration in silica, polymer chain vibration in organic bridges, which is a kind of solution/diffusion mechanism, can dominate the permeation properties. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4491–4498, 2017