Caged multiwalled carbon nanotubes as the adsorbents for affinity-based elimination of ionic dyes

Multiwalled carbon nanotubes (MWCNTs) were used as the active elements for the first time for affinity-based elimination of ionic dyes. MWCNTs were encapsulated in cross-linked alginate (ALG) microvesicles using Ba2+ as the bridging ion. The Ba2+-alginate matrix constitutes a cage which holds the physically trapped MWCNTs. The cage carries negative charges on its surface. The cage restricts the access of anions of large molecular weight, such as humic acids, because of electrostatic repulsion. The cage also restricts the access of colloids of large size, because of size exclusion. Ionic dyes partition into the cage and then are captured by MWCNTs probably on the basis of van der Waals interactions occurring between the hexagonally arrayed carbon atoms in the graphite sheet of MWCNTs and the aromatic backbones of the dyes. As a result of these interactions the target species, namely, the ionic dyes, are eliminated efficiently by the MWCNTs of Ba2+-ALG/MWCNT composite adsorbents. The adsorptive capacities for elimination of acridine orange, ethidium bromide, eosin bluish, and orange G (the model species used for this study) were found as high as 0.44, 0.43, 0.33, and 0.31 micromol, respectively, for 1.0 mg of the caged MWCNTs. Adsorptive experiments with carbon nanofibers and activated carbons as the adsorbents were also performed. The MWCNT-based adsorbents provided the best capability for the affinity-based elimination of these targeted species. Biocompatibility experiments performed in vitro and in vivo provided promising results, suggesting potential applications of the caged MWCNTs in in situ environmental remediation.     

Synthesis of spherical LiMn2O4 microparticles by a combination of spray pyrolysis and drying method

Lithium manganese oxide (LiMn₂O₄) has been synthesized by a spray pyrolysis method from the precursor solution; LiNO₃ and Mn(NO₃)₂·6H₂O were stoichiometrically dissolved into distilled water. The synthesized LiMn₂O₄ particles exhibited a pure cubic spinel structure in the X-ray diffraction (XRD) patterns, however they were spherical hollow spheres for various concentrations of precursor solution. Thus, the as-prepared LiMn₂O₄ particles were then ground in a mortar and dispersed into distilled water. To make a well dispersed slurry solution, a dispersion agent was also added into the slurry solution. The LiMn₂O₄ microparticles with a spherical nanostructure were finally prepared by a spray drying method from the slurry solution. The tap density of the LiMn₂O₄ microparticle prepared by a combination of spray pyrolysis and drying method was larger than that by a conventional spray pyrolysis method.The as-prepared samples were sintered at 750 °C for 1 h in air and used as cathode active materials for lithium batteries. Test experiments in the electrochemical cell Li|1 M LiClO₄ in EC:DEC = 1:1|LiMn₂O₄ demonstrate that the sample prepared by the present method is a promising cathode active material for 4 V lithium-ion batteries at high-charge-discharge and elevated temperature operation. The LiMn₂O₄ compounds by the combination of spray pyrolysis and drying method are superior to that by the conventional spray pyrolysis method in terms of electrochemical characteristics and tap density.     

Microbial conversion of palmitoleic acid to 9,12-hexadecadienoic acid (16:2ω4) by Trichoderma sp. AM076

Trichoderma sp. AM076, isolated from a freshwater sample, was found to accumulate 9,12-cis-hexadecadienoic acid (16:2ω4), when grown with palmitoleic acid (16: 1ω7). Methyl myristate was the best carbon source for the conversion of palmitoleic acid to 16:2ω4. The mycelial 16:2ω4 content reached 17.4 mg/g dry mycelia (443 mg/L) when the fungus was grown in a medium that contained 2.0% methyl myristate, 1.5% yeast extract, and 2.0% methyl palmitoleate, pH 6.0, for 5 d at 28°C with shaking. In both nonpolar and polar lipids from the mycelia, 16:2ω4 was detected as one of the major fatty acids when 16:1ω7 was added. It is probable that 16:1ω7 is converted to 16:2ω4 through the Δ12 desaturation reaction.     

Efficient preparation of novel fluoroalkyl end‐capped oligomers/titanium dioxide nanocomposites

Novel fluoroalky end‐capped oligomers/titanium dioxide nanocomposites were prepared by the hydrolysis of titanium isopropoxide in the presence of fluoroalkyl end‐capped N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide oligomer [R_F‐(DOBAA)_n‐R_F], fluoroalkyl end‐capped N,N‐dimethylacrylamide oligomer [R_F‐(DMAA)_n‐R_F], and fluoroalkyl end‐capped acrylic acid oligomer [R_F‐(ACA)_n‐R_F] in tetrahydrofuran under mild conditions. In these fluorinated oligomers, R_F‐(ACA)_n‐R_F oligomer is more effective for the preparation of the corresponding oligomers/titanium dioxide nanocomposites, and this oligomer can afford the expected fluorinated titanium dioxide nanocomposites in higher isolated yields. In addition, R_F‐(ACA)_n‐R_F/titanium dioxide composites are nanometer size‐controlled very fine nanoparticles (14–48 nm), and exhibited a good dispersibility not only in water but also in traditional organic solvents. Fluoroalkyl end‐capped oligomers/titanium dioxide nanocomposites were also applied to the surface modification of the common organic polymers such as poly(methyl methacrylate) to exhibit a good oleophobic and hydrophilic characteristics on the surface. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers.     

Characterization and functional properties of soybean high-molecular-mass polysaccharide complex

Soybean soluble polysaccharide (SSPS), extracted from the by-product obtained during isolation of soybean protein, is an anionic polysaccharide that stabilizes milk proteins under acidic conditions. We developed a high-molecular-mass complex of SSPS cross-linked via phosphate (SSPS-HC; absolute molecular weight = 2850 kg/mol, radius of gyration = 106 nm), and found that it has different protein stabilization properties when compared with the original SSPS (absolute molecular weight = 550 kg/mol, radius of gyration = 36 nm). The objective of this work was not only to study the rheological properties of SSPS-HC, but also clarify its protein-stabilizing properties in comparison with SSPS; if molecular mass or negative charge affected protein dispersion. Irrespective of high-molecular-mass, SSPS-HC possessed similar rheological properties to SSPS such as low viscosity in aqueous solution. The absolute negative charges of SSPS-HC measured by a zeta potential analyzer at pH range of 2.0–7.0 were higher than those of SSPS. Acidified milk drinks prepared with 8.4% non-fat milk solids and 0.4% SSPS-HC or SSPS showed low viscosity and small protein particle size, and did not aggregate for 14 days. The thickness of the hydrated layer, which was formed on the surface of protein particles by SSPS molecules measured after hemicellulase treatment with DLS (dynamic light scattering), was estimated to be about 89 nm for SSPS-HC and 33 nm for SSPS. These numerical values were in good relation to the molecular diameter of SSPS-HC and SSPS in aqueous solution measured by DLS and AFM image, and suggested that protein particles were dispersed and the hydrated monolayer made on the surface of protein particles by SSPS-HC or SSPS molecules prevented aggregation. However, stabilizing pH ranges were different with stability of SSPS-HC at pH range of 4.0–4.8 and stability for SSPS at pH range of 3.6–4.2. In addition to the difference in the molecular mass and absolute negative charge, the phosphate groups of SSPS-HC were possibly influenced on the protein-dispersing property approximately at isoelectric point of milk protein; SSPS-HC prevent aggregation of casein by accelerating solubility of calcium phosphate under acidic conditions as is already reported in the starches phosphorylated.     

Gelation effect on the synthesis of high-aspect-ratio gold nanorods

The growth process of high-aspect-ratio gold nanorods in gelled surfactant solution was studied. As for the application of gold nanorods, the surface plasmon is quite useful, whose absorption depends on their aspect ratio. Hence it is important to synthesize gold nanorods with favorable aspect ratio in high yield. For shorter nanorods (aspect ratio < -10), the synthesis and the growth mechanism have been studied well. For the longer nanorods (aspect ratio > -30), however, the growth mechanism has not yet been understood well, although it has been known that the high-aspect-ratio gold nanorods could be synthesized in high yield in gelled surfactant solution. In this paper, we studied the relationship between the growth process of high-aspect-ratio gold nanorods and the gelation of surfactant growth-solution. Small angle X-ray scattering (SAXS) revealed the microscopic feature of gelation as the structural transition of self-assembly of surfactant molecules from micellar to lamellar. These results will be helpful for better understanding on the growth mechanism of high-aspect-ratio gold nanorods.     

The crowding-out effect of housing subsidies on parental support: evidence from Japanese mortgage tax credits

Children may receive monetary transfers from their parents when they attempt to purchase a home. This raises the question of whether a homeownership-related subsidy provided by government displaces transfers received from parents. The purpose of this paper is to examine this question empirically, using a sample of Japanese home-buying households that are benefiting from a mortgage tax credit (MTC) as a model case. In the empirical analysis, we offer a test of the effect of the MTC on both the extensive and the intensive margins using the overall sample as well as subsample groups. The empirical results, which use the full sample, indicate that the MTC crowds out parental transfers on both the extensive and the intensive margins. In particular, the estimates of the latter suggest an approximately 100 % displacement. Subsample analysis demonstrates that the crowding-out effect is strengthened when children are young, are of low-income group, and are living in the rental sector previously.     

Formation of a nanocrystalline surface layer on steels by air blast shot peening

A nanostructured surface layer was fabricated on two kinds of steels by means of air blast shot peening. The nanolayer shows a sharp boundary to the underlying work-hardened area and good thermal stability up to 873 K. It has much higher hardness than the work hardened region in both the as-treated and annealed states. When using small shot sizes, the nano area can be formed in very short treatment times, and the thickness and continuity of the nanolayer is enhanced. On the contrary, the nanocrystalline region is more difficult to synthesize when using large shot particles, even though the deformed area is much thicker. The effect of particle diameter is attributed to the different collision time and different strain rate of the treated materials.     

A simple diagnostic method for plasma jet in strong magnetic field

An experimental study was carried out to examine the effect of strong magnetic field on the characteristics of argon plasma jet. An approximate expression was introduced to the distribution of emission line intensity and the color intensity. The distribution of the emission intensity was compared to that of the color intensity. The modified profiles of the spectral intensity agree well with those of the color intensity. The two-point analysis, that is, a calculation method with only two selected wavelengths in Boltzmann plots, was selected in the evaluation of excitation temperature because the calculation becomes significantly simple. The lateral distribution of excitation temperature obtained from the modified intensity becomes more accurate than that without the approximation. The radial distributions of excitation temperature based on the Abel inversion can be determined by the present approximation. It is found that the simple diagnostic method can utilize for understanding the characteristics on plasma jet.