This paper has investigated the influence of alkali treatment on the acidic functional groups of rice hull charcoal and investigated the relationship between its cesium and strontium adsorption ability. In the alkali treatment, rice hull charcoal carbonized from 400 to 1000 °C was immersed in a basic aqueous solution. The pH of the rice hull charcoal increased after alkali treatment. Furthermore, the alkali treatment of rice hull charcoal carbonized at 400 and 600 °C increased the adsorption of cesium and strontium. In the FTIR results, the OH band of alkali-treated rice hull charcoal was stronger than that of the untreated rice hull charcoal. The mesopore volume of alkali-treated rice hull charcoal increased. The alkali-treated rice hull charcoal showed an increased pH, increased negative charge, and cleaved lactone rings contained compared to the untreated sample. In addition, the valence of acidic functional groups increased, and the adsorption ability of cesium and strontium improved.
Halloysite nanotubes (HNTs) were modified with (3-aminopropyl)triethoxysilane to introduce amino groups on the HNT surfaces. Subsequently, poly(amidoamine) (PAMAM) dendrimers were synthesized on the HNT surfaces through the alkylation with methyl acrylate and amidation with ethylenediamine. The buildup of generation was confirmed by FT-IR and XPS analysis. In addition, the back titration with NaOH showed that the amount of amino groups increased with the increase in the generation of PAMAM dendrimers. The adsorption capacity of Cr(VI) ions had the maximum value at pH 3.0 and 30°C. The results of the temperature dependence suggest that the aminosilane layer is subject to degradation at higher temperatures. Under the above optimum conditions, the adsorption capacity increased to 0.95 mmol/g, or 49.3 mg/g, for the HNT sample with 7th generation. This value is higher than or comparable to those of other adsorbents prepared from HNT. These results emphasize that HNT samples with PAMAM dendrimers exhibit a significant potential as an adsorbent for removal of Cr(VI) ions from aqueous medium and wastewaters.
We observed the luminescence of a chlorophyll and porous Si dispersion using the wavelength-selected excitation and time-gated photoluminescence methods to eliminate the autofluorescence of chlorophyll. Although the photoluminescence (PL) of chlorophyll was dominant when the chlorophyll and porous Si dispersion was excited using the 405 nm line, the autofluorescence of chlorophyll drastically decreased when the dispersion was excited using the 355 nm line. During the time-gated photoluminescence experiments, the autofluorescence of chlorophyll disappeared and the broadband PL that corresponded to porous Si was clearly observed. Thus, porous Si could be a very useful luminescent probe for plant imaging when using the wavelength-selected excitation and time-gated photoluminescence methods.
Many companies have been attempting to transfer the skills and knowledge of skilled workers to other inexperienced workers. The establishment of an efficient training method is also desired for gas tungsten arc welding (GTAW), which has high demand in the production fields of industrial equipment. This study focused on the brightness of the backside weld pool changing under GTAW conditions. The backside weld pool images during welding of a stainless steel plate were taken with a charge coupled device (CCD) camera from the bottom of the welding stage made of glass. The situation of the weld pool at the backside of the plate was visualized by a brightness map of the backside weld pool with the brightness on the horizontal axis and the number of pixels on the vertical axis. From this map, the torch control technique and quality of the backside bead could be numerically evaluated. Therefore, the map suggests that the GTAW skills could be visualized. This could improve welding skill easily and also contribute to highly efficient training, education, and transfer of skills, because the brightness map of the backside weld pool reveals the weaknesses of the welder.
Investigated are asymmetric redirection waveguides that are to couple to a solar-cell unit placed at the end, converting 3D-photons of sunlight to 2D-photons. The redirection waveguide is equipped with two functions, the first of which is to make the 3D-photons coming from various directions go vertically with respect to a 2D-waveguide. The second function is to change the vertically going photons into lateral photons propagating in the 2D waveguide. The redirection waveguide can harvest photons coming in wide area and convey them to the solar-cell unit located at the periphery of the 2D waveguide, as a key element of concentrator solar-cell with high conversion efficiencies as well as of optical wireless power transmission systems.
In this work we have studied changes in the optical properties of silica after high dose spot-by-spot implantation of 1.450 MeV Au, 0.785 MeV Ag, and high temperature annealing, and the effect of the sequence of annealing and implantation. Using a 2 mm diameter aperture, each spot was implanted to desired dose before moving the spot by 0.5 mm increments laterally across the sample so that a 1 cm2 area was uniformly implanted. Total implantation fluences of Au, Ag, and (sequentially) Au + Ag were varied from 1.5 x 1016 /cm2 to 1.4 x 1017 /cm2, and the implanted area was studied before and after annealing using optical absorption photospectrometry and by Rutherford backscattering spectrometry (RBS). We found that a secondary implantation by Ag ions (after Au implantation & nanoparticle formation) facilitates substrate healing upon a second annealing step, returning the index of refraction to the value near to that of a pristine substrate, and Au nanoparticle absorption to that predicted by Mie theory. Changing the processing order of annealing (annealing after both Au and Ag implantations were completed, rather than between the Au and Ag implantations) eliminated Ag nanocluster formation, returned the substrate index of refraction to its pristine value, and caused Au nanocluster formation to initiate at lower annealing temperatures.
Pulsed-induced resistivity modulation of a Pt/Ti0.99Sc0.01O2-δ/Pt multilayer with a cross-point structure was investigated. This multilayer exhibits nonlinear current–voltage characteristic based on the Schottky barrier at the Pt/Ti0.99Sc0.01O2-δ interface. When the electrical pulses of 1.5 V were applied with short interval time of 10 s, the resistivity modulation corresponding to the long-term-memorization (LTM) were observed. X-ray photoemission spectroscopy showed O-H bond that contributes to electron-proton mixed conduction at the Pt/Ti0.99Sc0.01O2-δ interface. This LTM resistivity modulation is considered to be due to the local proton migration at the Pt/Ti0.99Sc0.01O2-δ interface, and the operation voltage is lower than that of the reported oxide multilayer.
CuO-TiO2-Nb2O5 was utilized as additive (5 wt%) to obtain densified alumina using the firing temperature of 885 °C for 96 h. Densification started at ~835 °C, which was lower than the melting point of the additive (~967 °C). The melting temperature of the powder mixture consisting of the additive and alumina was measured, but no significant changes were observed compared with the melting temperature of the additive. Furthermore, the lattice constants measurements of the alumina sample obtained after heat treatment at 885 °C revealed an increase in unit cell volume, which suggested the incorporation of Cu and Ti components into alumina according to the TEM-EDS analysis. In addition, the timing of the increase in alumina lattice constant and that of the rapid increase in the sintered density of the additive-containing alumina coincided. These results indicated that the densification of the sample occurred in solid state (solid-state-activated sintering). The sample fired at 935 °C for 6 h exhibited the thermal conductivity of 22 W/mK, which was higher than that of conventional low-temperature co-fired ceramic materials (~2–7 W/mK), the relative dielectric constant (εr) of 10.2, the quality factor multiplied by the resonant frequency (Q × f) value of 47000 GHz, and the temperature coefficient of resonant frequency (τf) of –50 ppm/K.