Clear and simple detection of asbestos stained with two dyes for building materials collected from disaster and demolition sites using a stereomicroscope.

Whenever houses are demolished or disasters occur, large quantities of building materials are discharged, which may contain asbestos. To prevent the damage caused by asbestos exposure, a rapid asbestos presence confirmation method is required at demolition sites or temporary disaster storage sites. It is difficult to confirm the presence of asbestos in waste building materials by simple observation. However, it can be confirmed by staining the materials with two dyes: methylene blue (MB) with positive charge, and erythrosine (RED-3) with negative charge, and using a stereomicroscope. The method was applied to samples collected from disaster and demolition sites. Asbestos was stained violet or reddish-purple, and the base material of the building materials remained blue. Using this method, even amateur workers can detect asbestos by means of an image in a different color than the building substrate. Furthermore, the present method detected asbestos more explicitly than the official method (JIS A 1482, 1483; detection limit is < 0.1%) recommended by the Japanese government. This cost-effective method is suitable for detecting asbestos at disaster and demolition sites. The mixture of MB and RED-3 formed nanoparticles of size 151 nm and surface charge of -34 mV that selectively stained asbestos. The staining mechanism was discussed.

On-site detection of asbestos at the surface of building materials wasted at disaster sites by staining.

We have developed a method to detect asbestos by staining the surface of building materials in order to quickly detect asbestos-containing building materials at disaster sites. After staining, asbestos was easily detected by the color and characteristic shape of the images observed under a stereomicroscope. The type of asbestos was confirmed to be chrysotile by polarized light microscopy, X-ray diffraction patterns, and Raman spectra. The percentage of the area of asbestos at the surface of building materials was also determined by an image analyzer after the dye staining, and the distribution percentage of asbestos increased with its total concentration in the building material. Three-dimensional X-ray computed tomography images showed that asbestos was mainly distributed at the surface of building materials. This result suggests that the asbestos at the surface of debris of building materials is more easily and sensitively detected than total asbestos analysis by pulverization. The present method was applied to detect and determine asbestos in debris of building materials wasted at temporary storage sites after disaster and on the wall of a building in use. Therefore, this method can contribute to the classification of asbestos-containing and non-asbestos-containing building materials at disaster sites and demolition sites, as well as to preliminary inspections for the detection of asbestos-containing building materials before demolition of houses and buildings.

Synthesis and controllable wettability of micro- and nanostructured titanium phosphate thin films formed on titanium plates.

The hydrothermal treatment of a titanium plate in a mixed aqueous solution of hydrogen peroxide and aqueous phosphoric acid under different conditions results in the formation of various titanium phosphate thin films. The films have various crystal structures such as Ti2O3(H2PO4)2·2H2O, α-titanium phosphate (Ti(HPO4)2·H2O), π-titanium phosphate (Ti2O(PO4)2·H2O), or low-crystallinity titanium phosphate and different morphologies that have not been previously reported such as nanobelts, microflowers, nanosheets, nanorods, or nanoplates. The present study also suggests the mechanisms behind the formation of these thin films. The crystal structure and morphology of the titanium phosphate thin films depend strongly on the concentration of the aqueous hydrogen peroxide solution, the amount of phosphoric acid, and the reaction temperature. In particular, hydrogen peroxide plays an important role in the formation of the titanium phosphate thin films. Moreover, controllable wettability of the titanium phosphate thin films, including superhydrophilicity and superhydrophobicity, is reported. Superhydrophobic surfaces with controllable adhesion to water droplets are obtained on π-titanium phosphate nanorod thin films modified with alkylamine molecules. The adhesion force between a water droplet and the thin film depends on the alkyl chain length of the alkylamine and the duration of ultraviolet irradiation utilized for photocatalytic degradation.

Apatite-forming ability of titanium compound nanotube thin films formed on a titanium metal plate in a simulated body fluid.

We compared the apatite-forming ability of a sodium titanate nanotube thin film, an anatase-type titanium dioxide nanotube thin film, and a silver nanoparticle/silver titanate nanotube nanocomposite thin film, in simulated body fluid. The ability of the silver nanoparticle/silver titanate nanotube nanocomposite thin film is slightly higher than that of the anatase-type titanium dioxide nanotube thin film and significantly higher than that of the sodium titanate nanotube thin film. The high ability of the silver nanoparticle/silver titanate nanotube nanocomposite thin film is a newly observed phenomenon, which is probably due to the crystal structure of silver titanate--specifically, to the surface atomic arrangement, the large amount of Ti-OH formed on the nanotube surface, or both. The anatase-type titanium dioxide nanotube thin film and the silver nanoparticle/silver titanate nanotube nanocomposite thin film may have bright prospects for future use in implant materials such as artificial joints. The silver nanoparticle/silver titanate nanotube nanocomposite thin film is particularly promising for its antibacterial properties.

Antibacterial properties of nanostructured silver titanate thin films formed on a titanium plate.

Antibacterial activity of various surfaces against methicillin-resistant Staphylococcus aureus (MRSA) was studied. Sodium titanate thin film with a porous network structure and sodium titanate nanotube thin film were formed on titanium surfaces through the reaction of titanium plates with NaOH solutions. Through a silver ion-exchange treatment, Na(+) ions in sodium titanate were exchanged with Ag(+) ions in silver acetate solution, along with the loading of silver nanoparticles on the titanate surfaces. Results of silver ion elution tests of the thin films in fetal bovine serum solution indicate that the release period and the number of silver ions released from the silver titanate thin films can be controlled by altering the crystal structure, nanostructure, and thickness of the titanate phase. The silver ion-exchanged titanate thin films showed high antibacterial activity against MRSA. It was also revealed that although the crystal structure of titanate itself has no large antibacterial effect, higher antibacterial activity mainly arises from the silver ions held in the interlayer spacing of the titanate. The obtained results should aid the development of more convenient and inexpensive antibacterial implants.

Chemical modification of carbonized wheat and barley straw using HNO3 and the adsorption of Cr(III).

The effects of oxidation using HNO(3) on the properties of the carbonized wheat and barley straw were investigated by measuring different properties such as specific surface area, PZC, total surface acidic groups as well as FTIR and TG-DTA. A small decrease in the specific surface area due to pore blockage was observed after oxidation. After oxidation, the acidity was increased considerably and the point of zero charge shifted from approximately pH 9 to pH 2 in both types of carbon. By the oxidation of the carbon with nitric acid, carboxylic groups were produced as shown by absorption peaks at 1750 cm(-1) in the FTIR spectra. Boehm titration results showed that the number of carboxyl groups increased by approximately 11-fold after oxidation. The oxidized carbon samples were compared with the unoxidized original carbon samples for Cr(III) adsorption. It was observed that the oxidized carbons exhibit high adsorption efficiencies for Cr(III) ions compared to the original carbonized straws and this can be correlated to the decrease in PZC which is mainly due to the increase in carboxylic functional groups in the oxidized carbonized straws and these are responsible for their cation ion exchange phenomenon.

Plate, wire, mesh, microsphere, and microtube composed of sodium titanate nanotubes on a titanium metal template.

Sodium titanate nanotube/titanium metal composites were synthesized by hydrothermal treatment of titanium metals with various morphologies such as plate, wire, mesh, microsphere, and microtube at 160 degrees C in aqueous NaOH solution and by the subsequent fixation treatment by calcination at 300 degrees C. The surface of the composite was covered with sodium titanate nanotubes with a diameter of approximately 7 nm, and the core part of the composite was titanium metal phase. The raw titanium metal acts as a template or a morphology-directing agent of micrometer size or more to arrange the nanotubes as well as a titanium source for the formation of nanotubes. The concentration of titanium species increases in the reaction solution as the dissolution of titanium metal is accelerated by the reaction between titanium and OH-. Furthermore, with an increase in concentration of titanium species in the reaction solution, the titanium species are re-precipitated as sodium titanate nanotubes onto the titanium metal. Titanium metal with a large surface area and volume can form sodium titanate nanotubes on the surface of the titanium metal, though titanium metal with a small volume and surface area tends to dissolve with the hydrothermal treatment. Even in the synthesis using titanium metal with a small volume and surface area, sodium titanate nanotubes are formed and cover the surface of the titanium metal by adding another titanium metal as a source of titanium species in the reaction solution.

Yttrium-Based Porous Materials Templated by Anionic Surfactant Assemblies.

The layered and hexagonal yttrium-based surfactant mesophases templated by anionic surfactant (C(n)()H(2)(n)()(+1)OSO(3)(-) and C(n)()H(2)(n)()(+1)SO(3)(-)) assemblies were synthesized by the homogeneous precipitation method using urea. The layered mesophase is formed of a layered but curving or bending microstructure and transformed into a hexagonal mesostructure with complex and attractive morphologies such as plate-, dish-, and crown-like shapes. The specific surface area of the mesostructured solid increases from 53 m(2) g(-)(1) for the layered form to 251-322 m(2) g(-)(1) for the hexagonal form, due to the formation of hexagonally arranged cylindrical micropores loosely occupied by surfactant molecules. The anion-exchange of the hexagonal mesophase with acetate species results in a mesoporous material with a specific surface area of as large as 545 m(2) g(-)(1).