Gas Storage in Single-Walled Carbon Nanotubes

Abstract

X-ray diffraction (XRD) and electrical resistance measurement on single-walled carbon nan-otube (SWNT) samples prepared by the arc-discharge method are reported. The XRD profile of heat-treated sample indicated that air (oxygen, and/or nitrogen and/or water) can be condensed inside the SWNTs. We also found that the electrical resistance of SWNT soot is significantly affected by exposing to the oxygen gas and humid air.     

A generalized bi-criteria fuzzy integer flow sharing problem

The flow sharing problem is a class of techniques that can be used to find the optimal flow in a capacitated network, which realizes an equitable distribution of flows. This paper extends the integer flow sharing problem by considering fuzzy capacities and fuzzy weights such that the flux received at each sink node and the flow value through each arc are restricted to be multiples of some block unit. Fuzzy capacity describes the flexibility of the upper limit of flow value through each arc. Fuzzy weight represents the degree of satisfaction of the flux to a sink node. Our model has the two following criteria: to maximize the minimal degree of satisfaction among all of the fuzzy capacity constraints and to maximize the minimal degree of satisfaction among the fluxes to all of the sink nodes. Because an optimal flow pattern that simultaneously maximizes the two objectives is usually not feasible, we define non-domination in this setting and propose a pseudo-polynomial algorithm that finds some non-dominated flow patterns. Finally, a numerical example is presented to demonstrate how our algorithm works.     

Measurement technique for depth profiling in time-domain low-coherence interferometer

A measurement technique for depth profiling in a time-domain low-coherence interferometer has been proposed. The spatial variation of the optical path caused by a diffraction grating in the Littrow configuration produces a white-light interferogram. A one-dimensional charge-coupled device (1D-CCD) detector is used to measure the undersampled white-light interferogram. The position of the reflective boundary is calculated from the rate of phase change with spatial frequency, which is based on the sub-Nyquist sampling of the white-light interferogram in the frequency domain.     

Chemoselective Oxidation of Secondary Hydroxy Functions Catalyzed by [PMo12O40]3-[C5H5N+(CH2)15 CH3]3

Abstract

The epoxidation of allylic alcohols with H₂O₂ catalyzed by a new Mo-species, [PMo₁₂O₄₀]^3?[C₅H₅N⁺(CH₂)₁₅CH₃]₃ (MPCP), prepared from 12-molybdatophosphoric acid (H₃PMo₁₂O₄₀) and cetylpyridinium chloride [C₅H₅N⁺(CH₂)₁₅CH₃ · Cl^?], has recently rep0rted.) The high regioselectivity for the epoxidation by this MPCP-H₂O₂ system was comparable to that of Sharpless method using t-BuOOH as oxidant.     

Ketonization of Secondary Hydroxy Groups of Alcohols and Diols with Hydrogen Peroxide Under the Influence of Tricetylpyridinium-12-Tungstophosphate

Molydbenum and tungsten-catalyzed oxidations of alcohols with dilute hydrogen peroxide under phase-transfer conditions have been focused in recent years 1–3. In a previous paper, we have reported that tricetylpyridinium-12-molybdophosphate(CMP), [π - C₅H₅N+(CH_{2 15}CH₃]₃ (PMO₁₂O₄₀)³-, prepared from 12-molybdophosphoric acid (MPA) and cetylpyridinium chloride (CPC), catalyzed the oxidation of secondary alcohols to carbonyl compounds with tert-butylhydroperoxide(t-BuOOH)⁴. When hydrogen peroxide in place of t-BuOOH was employed as the oxidant for the above oxidation, however, alcohols were oxidized with difficulty to give carbonyl compounds in poor yields. In continuation of this study, we wish to report here the selective oxidation of secondary hydroxy group of alcohols and diols and diols with H₂O₂ under the influence to tricetylpyridinium-12 tungstophosphate (CWP), [π-C₅H₅N+ (CH₂) 15 CH₃]₃(PW₁₂O₄₀)³-, derived from 12-tungstophosporic acid (WPA) and CPC.     

Thermal oxidative degradation of additive-free polypropylene pellets investigated by multichannel Fourier-transform chemiluminescence spectroscopy

Thermal oxidative degradation of additive-free polypropylene pellets heated isothermally in dry air at 150 and 180 °C (below and above the melting point of 163 °C) was investigated by multichannel Fourier-transform chemiluminescence spectroscopy. The initial peak wavelength of chemiluminescence emission at 490 nm remained constant during the early stages of thermal degradation, but new emissions developed with time in the red spectral region over an extended oxidation period. The time-dependent luminescence spectra were deconvoluted into three emission bands by least-squares fitting using Gaussian curves. We concluded that at least three groups of luminescent species (luminophores), having different conjugation lengths, were generated by thermal oxidation over extended periods and show luminescence around 490, 660, and 740 nm.     

Enhancing the Cellulose-Degrading Activity of Cellulolytic Bacteria CTL-6 (Clostridium thermocellum) by Co-Culture with Non-cellulolytic Bacteria W2-10 (Geobacillus sp.)

The effect of a non-cellulolytic bacterium W2-10 (Geobacillus sp.) on the cellulose-degrading activity of a cellulolytic bacterium CTL-6 (Clostridium thermocellum) was determined using cellulose materials (paper and straw) in peptone cellulose solution (PCS) medium under aerobic conditions. The results indicated that in the co-culture, addition of W2-10 resulted in a balanced medium pH, and may provide the required anaerobic environment for CTL-6. Overall, addition of W2-10 was beneficial to CTL-6 growth in the adverse environment of the PCS medium. In co-culture with W2-10, the CTL-6 cellulose degradation efficiency of filter paper and alkaline-treated wheat straw significantly increased up to 72.45 and 37.79 %, respectively. The CMCase activity and biomass of CTL-6 also increased from 0.23 U ml^?1 and 45.1 μg ml^?1 (DNA content) up to 0.47 U ml^?1 and 112.2 μg ml^?1, respectively. In addition, co-culture resulted in accumulation of acetate and propionate up to 4.26 and 2.76 mg ml^?1. This was a respective increase of 2.58 and 4.45 times, in comparison to the monoculture with CTL-6.     

Preparation of various Janus composite particles with two components differently combined

Janus composite particles with a combination of organic and inorganic substances were synthesized by soap-free emulsion polymerization in which an amphoteric initiator of 2,2′-azobis[N-(2-carboxyethyl)-2-2-methylpropionamidine] (VA-057) was employed to introduce a polystyrene (PSt) lobe onto silica cores surface-modified with 3-methacryloxypropyltrimethoxy silane (MPTMS). Thermogravimetric analysis and X-ray photoelectron spectroscopy were used to characterize the surface-modified silica particles and showed that a small amount of MPTMS introduced onto the surface of silica particles could successfully prepare SiO₂–PSt Janus particles. The oxide part of SiO₂–PSt Janus particles obtained with the polymerization was further surface-modified with 3-aminopropyltriethoxysilane (APS) to introduce positively charged amino groups on the silica surface. The silica surface modified with APS was covered with gold by electroless deposition in which a gold precursor of auric chloride was reduced with ascorbic acid in the presence of polyvinylpyrrolidone. The electroless deposition of gold successfully produced Janus particles with a combination of gold and PSt surfaces. Furthermore, dissolution of the polymer component of the Au–PSt Janus particles in tetrahydrofuran led to another Janus type of particles with an inorganic combination of Au and SiO₂.     

A Defective Nanotube Molecule of C552H496N24 with Pyridinic and Pyrrolic Nitrogen Atoms

A 3-nm molecule comprising a cylindrical core and cross-shaped rims was designed and synthesized by developing a modular synthetic route. By using a cyclic precursor from previous studies as a starting material, multiple carbazole units were installed at the rims of the defective cylinder. The defective cylinder was synthetically doped with two types of nitrogen atoms, that is, pyridinic and pyrrolic nitrogen atoms, which resulted in solvatochromic shifts in fluorescence by charge-transfer interactions. The structure of the large, C₅₅₂H₄₉₆N₂₄ molecule was fully disclosed by crystallographic analyses, and the unique helical arrangement of nitrogen-doped cylinders in the crystal was revealed.     

Selective ablation of atherosclerotic lesions with less thermal damage by controlling the pulse structure of a quantum cascade laser in the 5.7-µm wavelength range

Cholesteryl esters are the main components of atherosclerotic plaques, and they have an absorption peak at the wavelength of 5.75 µm. To realize less-invasive ablation of the atherosclerotic plaques using a quasi-continuous wave (quasi-CW) quantum cascade laser (QCL), the thermal effects on normal vessels must be reduced. In this study, we attempted to reduce the thermal effects by controlling the pulse structure. The irradiation effects on rabbit atherosclerotic aortas using macro pulse irradiation (irradiation of pulses at intervals) and conventional quasi-CW irradiation were compared. The macro pulse width and the macro pulse interval were determined based on the thermal relaxation time of atherosclerotic and normal aortas in the oscillation wavelength of the QCL. The ablation depth increased and the coagulation width decreased using macro pulse irradiation. Moreover, difference in ablation depth between the atherosclerotic and normal rabbit aortas using macro pulse irradiation was confirmed. Therefore, the QCL in the 5.7-µm wavelength range with controlling the pulse structure was effective for less-invasive laser angioplasty.