Magnetostriction measurements have been made in an ordered Fe3Pt single crystal with degree of order of about 0.8, which exhibits a cubic-tetragonal martensitic transformation at 97 K. The specimen was cooled down to 4.2 K without magnetic field, and then a magnetic field of 4 T is applied to the specimen along 〈001〉 at 4.2 K and removed. As a result, a reversible giant magnetostriction of about 0.5% is observed. This reversible magnetostriction will be caused by the rearrangement of crystallographic domains, being three times as large as that of Terfenol-D (Fe2DyxTb1−x: typical magnetostrictive materials).
Monitoring the gases released during breathing or via the skin has gained significance towards diagnosing diseases. In this study, a sensor chip capable of detecting nonanal gas, which is known to be a marker of lung cancer, was developed. The gas detection agent used was vanillin, which underwent aldol condensation with nonanal in the presence of a basic catalyst, resulting in the formation of an unsaturated aldehyde. Porous glass was used as the reaction field to carry the detection agent. Alkali-resistant porous glass was chosen because conventional porous glasses show low durabilities under basic conditions, as they primarily consist of SiO 2 . Nonanal can be detected through changes in the absorption spectrum of the sensor. An accumulatetype sensor was used in this study, which exhibited a linear relationship between the degree of absorption changes at 470 nm and nonanal concentration in the 60 ppb-1.3 ppm range. Therefore, this biological marker gas sensor is effective for the early diagnosis of diseases. The alkali-resistant porous glass sensor chip exhibited a higher degree of absorption change than the conventional porous glass sensor chip.
Transmittance in
porous-glass gas sensors, which use aldol condensation
of vanillin and nonanal as the detection mechanism for nonanal, decreases
because of the production of carbonates by the sodium hydroxide catalyst.
In this study, the reasons for the decrease in transmittance and the
measures to overcome this issue were investigated. Alkali-resistant
porous glass with nanoscale porosity and light transparency was employed
as a reaction field in a nonanal gas sensor using ammonia-catalyzed
aldol condensation. In this sensor, the gas detection mechanism involves
measuring the changes in light absorption of vanillin arising from
aldol condensation with nonanal. Furthermore, the problem of carbonate
precipitation was solved with the use of ammonia as the catalyst,
which effectively resolves the issue of reduced transmittance that
occurs when a strong base, such as sodium hydroxide, is used as a
catalyst. Additionally, the alkali-resistant glass exhibited solid
acidity because of the incorporated SiO2 and ZrO2 additives, which supported approximately 50 times more ammonia on
the glass surface for a longer duration than a conventional sensor.
Moreover, the detection limit obtained from multiple measurements
was approximately 0.66 ppm. In summary, the developed sensor exhibits
a high sensitivity to minute changes in the absorbance spectrum because
of the reduction in the baseline noise of the matrix transmittance.
We tried to synthesize zeolite from the sand-like particles of crushed LCD panel glass collected from discarded electronics devices. In the previous study, zeolite A was synthesized using fine glass particles of <10 m. Acid treatment was found effective toward synthesizing single phase zeolite A. Using sand-like coarse glass particles, of which the internal-core consists of glass and the surficial shell transforms into zeolite, we investigated the effect of acid-treatment by evaluating the surface of the coarse glass particles. Under acid-treatment, components other than Si eluted from the glass. The elution amounts were several percent of the total glass mass. After acid-treatment, the surface of the glass particle was discovered to be covered in a thin layer of poor components other than Si and a relatively rich quantity of Si, by scanning electron microscopy and energy dispersive spectrum analysis. The synthesized zeolite A increased the longer the acid-treatment time, which suggest the thin layer increased. When the concentration of the acid solution decreased, glass components other than Si dissolved well, and the synthesized zeolite A increased as a result. This indicates that the Si-rich layer is necessary for preferential synthesis of zeolite A from crushed particles of aluminoborosilicate glass.
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