Development of two-dimensional gas chromatography/isotope ratio mass spectrometry for the stable carbon isotopic analysis of C(2)-C(5) non-methane hydrocarbons emitted from biomass burning

A two-dimensional gas chromatography/combustion/isotope ratio mass spectrometry (2D-GC/C/IRMS) system was developed for stable carbon isotopic measurements of C(2)-C(5) non-methane hydrocarbons (NMHCs) in biomass burning smoke. The 2D-GC/C/IRMS system successfully improved the accuracy and precision for the measurements of C(4) and C(5) saturated compounds in a smoke sample by selective injection of target compounds into a combustion furnace and consequently allowed us to provide complete baseline separation for all individual NMHCs. The analytical precision of the delta(13)C of each compound was better than 0.5 per thousand for more than 500 pmolC injections and 2.1 per thousand for 30 pmolC injections, which was estimated from replicate analysis of standard gases. This system was applied to the analysis of NMHCs in smoke samples collected from laboratory biomass burning experiments. From the combustion of three fuel materials (rice straw, pine wood, and maize), we found that the isotopic fractionation between fuel material and individual NMHCs is almost independent of the fuel material and thus the delta(13)C values of the fuel materials are reflected in delta(13)C values of most of NMHCs. However, only i-butane emitted from maize combustion showed anomalous (13)C-depletion of -11.6 per thousand relative to the delta(13)C value of maize. Such a large (13)C depletion suggests the specific isotopic fractionation process which is attributed to the maize combustion itself or the chemical properties of i-butane during production from a radical recombination reaction.     

Facile synthesis of aryl ether dendrimer from unprotected AB2 building blocks using thionyl chloride as an activating agent

[structure: see text] A novel, rapid, inexpensive, and highly efficient convergent approach for the synthesis of a Fréchet- type aryl ether dendrimer using thionyl chloride has been developed. In this method, the purification of each dendron and a dendrimer occurs by recrystallization, extraction, and precipitation. The MALDI-TOF MS spectrum supported the formation of the G2, G3, and G4 dendrons and the star-shaped G4 dendrimer.     

Formation of nanotubes TiO2 from layered titanate particles by a soft chemical process

Nanotubes TiO₂ were synthesized from layered titanate Na₂Ti₃O₇ particles by a soft chemical process. These nanotubes have a hollow structure with an opening end. The wall of nanotubes is very well crystallized multi-wall structure. The inner diameters of nanotubes are ca. 30-40 nm and the length up to several hundreds nanometers. XRD results show that TiO₂ phase was formed during the procedure of exfoliating Na₂Ti₃O₇ particles into nanosheets. Based on our experimental results, an exfoliating-rolling model was proposed for formation of nanotube structure.     

Synthesis of proton‐conducting block copolymer membranes composed of a fluorinated segment and a sulfonic acid segment

Diblock copolymer membranes having a fluorinated segment and a sulfonic acid segment were prepared by living radical polymerization, solution casting, and crosslinking, followed by heat treatment. Diblock copolymers of 2,3,4,5,6‐pentafluorostyrene (PFS)/4‐(1‐methylsilacyclobutyl)styrene (SBS) and neopentyl styrenesulfonate (SSPen) (poly(PFS‐co‐SBS)‐b‐polySSPen)s were synthesized by nitoroxy‐mediated living radical polymerization. Self‐standing crosslinked membranes were obtained by casting a THF solution of the block copolymer with Pt catalyst. Heat treatment of the membrane at 230 °C induced decomposition of the neopentyl sulfonate esters to provide block copolymer membranes having a fluorinated segment and a free sulfonic acid segment. It was confirmed that the block copolymer with a high sulfonic acid content exhibited high ion exchange capacity and high proton conductivity as well as high thermal stability. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4479–4485, 2008     

Theoretical investigation of the reflectivity of fullerene-(C60, C70)/AlN multilayers in UV region

Theoretical calculations via a transfer matrix method (TMM) were performed to investigate the possibility of fullerene/AlN multilayer films acting as one-dimensional (1D) photonic band gap (PBG) crystals. The response within and out of the periodic plane of (C₆₀, C₇₀)/AlN multilayers was studied. (C₆₀, C₇₀)/AlN multilayer films presented incomplete PBG behavior in UV region. C₆₀/AlN multilayers with two pairs of 49 nm-C₆₀ and 21 nm-AlN layers exhibited a high reflectivity of 90.4% at a wavelength of about 200 nm. As a consequence, this photonic crystal may be important for achieving materials with an incomplete band gap in the UV region.     

Enhanced emission of single quantum dot formed by interface fluctuations in photonic-crystal microcavities

We fabricated photonic-crystal (PhC) microcavities tuned to GaAs quantum dots (QDs) formed by interface fluctuation for the first time and observed the spontaneous emission enhancement in a weak coupling regime. A QD is a very thin GaAs quantum well (QW), and its interface steps exhibit quantum dot-like behavior. The emission intensity from the PhC cavity was stronger than that from the area where no PhC pattern was fabricated and the overall shape of the photoluminescence (PL) agreed with the cavity mode calculated with the three-dimensional (3D) finite-difference time domain (FDTD) method. The spontaneous emission enhancement factor was 10.     

Relationships between arithmetic averages of sound pressure level calculated in octave bands and Zwicker’s loudness level

Previously it has been found through a series of psychoacoustical experiments that the arithmetic average of sound pressure level calculated in octave bands is a good estimator of loudness for various kinds of environmental noise. Remarkably, the arithmetic average of sound pressure level in octave bands from 63 Hz to 4 kHz, L_m,1/1(63-4k), strongly correlates with the loudness level specified in ISO 532B, LL(Z), as well as with loudness assessment. To investigate this relationship further, a numerical study has been carried out based on Zwicker’s loudness model. As a result, practical expressions to estimate the loudness levels of general environmental noises from the sound pressure levels in octave bands from 63 Hz or 125 Hz to 4 kHz are proposed.     

Energy distribution around 175 MeV Ar ion path in argon at the density of water

The ionization distribution in Ar gas by 175 MeV Ar ion was measured, and reduced to the energy density as a function of the radial distance in water. The energy density within the radial distance smaller than 294 nm decreased proportionally to the inverse of the square of the distance. Beyond this distance, however, the energy density decreased more steeply. The deposited energy except in the core region of the track amounts to 89% of linear energy transfer (LET).