Quantitatively chemo-fluorometry diagnostic to nitrite ion in ultrasound aqueous medium containing 2,3-diaminonaphthalene

Sonochemical nitrogen fixation for the generation of NO2- and NO3- ions under high-powered ultrasound in aqueous medium

Sonochemical species such as nitrite (NO₂^-) and nitrate (NO₃^-) were detected in ultrapure aqueous medium with 28 kHz low frequency ultrasound (US) in the range of 200-1200 W output power. The concentration of their anionic ions monitored with a high-performance liquid chromatography increased with increasing US power especially under air atmosphere. When the generation of NO₂^- and NO₃^- ions under US exposure was investigated for N₂, O₂ and Ar-bubbled solutions, no trace of NO₂^- was observed while NO₃^- was slightly generated. Under air atmosphere, the concentration of dissolved oxygen in the aqueous medium increased especially when 1200 W power was used. In addition, the bulk pH shifted towards the acidic side with an increase in exposure time, which indicated that NO₂^- was formed. The formation of oxidizing species under 28 kHz low frequency ultrasonic treatment was confirmed with an absorption spectrum which was dominated by two maxima peaks at 288 nm and 352 nm representing triiodide I₃^- anion.

Ultrasonic degradation of diaminobenzidine in aqueous medium

By using 500 kHz high frequency ultrasound (US), 3,3'-diaminobenzidine (DAB) was treated at pH 2 under air atmosphere. The US effect of DAB absorption at 280 nm was composed at 43 and 141 kHz for the detection of fluorescence. When 100 W of US power was used, the DAB absorption band decreased with exposure time. It was noted that, a new absorption broad band at 350 nm-500 nm appeared only under 141 and 500 kHz. Also, fluorescence spectra of the treated DAB were measured when excited at 370 nm. Increasing US exposure time resulted to a broad emission band at 478 nm, indicating that 1H,1'H-5,5'-Bibenzotriazole (BBT) was produced by US exposure at 500 kHz. This product was confirmed by NMR spectroscopy to be a triazine ring formed from NH₂ proton in DAB, due to the formation of nitrite ions in the US aqueous medium at 500 kHz. Hence, DAB was degraded while BBT was formed.

Numerical simulation of the red blood cell aggregation and deformation behaviors in ultrasonic field

The objective of this paper is to propose an immersed boundary lattice Boltzmann method (IB-LBM) considering the ultrasonic effect to simulate red blood cell (RBC) aggregation and deformation in ultrasonic field. Numerical examples involving the typical streamline, normalized out-of-plane vorticity contours and vector fields in pure plasma under three different ultrasound intensities are presented. Meanwhile, the corresponding transient aggregation behavior of RBCs, with special emphasis on the detailed process of RBC deformation, is shown. The numerical results reveal that the ultrasound wave acted on the pure plasma can lead to recirculation flow, which contributes to the RBCs aggregation and deformation in microvessel. Furthermore, increasing the intensity of the ultrasound wave can significantly enhance the aggregation and deformation of the RBCs. And the formation of the RBCs aggregation leads to the fluctuated and dropped vorticity value of plasma in return.

Coumarin fluorometry to quantitatively detectable OH radicals in ultrasound aqueous medium

When ultrasound (US) was exposed to aqueous coumarin solution in air atmosphere, the UV-visible and fluorescence spectra of the probe were measured at different US exposure times. The US exposure was carried out at 43 kHz and 500 kHz with different out-put power. It was found that the 500 kHz US produced umbelliferone fluorescence, while the 43 kHz US had no fluorescence. In addition, the coumarin absorbance at 270 nm maximum was decreased with in cases of the US exposure time. In contrary, the fluorescent intensity of umbelliferone at 460 nm increased with increasing of US exposure time. This exhibited that the coumarin probe was converted to umbelliferone by the US exposure, when the 500 kHz US was operated. This was facted that the coumarin framework was caused with addition of OH groups which was generated by the 500 kHz US. Therefore, the umbelliferone fluorescent became a probe to estimate OH radical in US medium. Furthermore, the chemo-fluorometry showed that the emission maximum of the formed umbelliferone could probe the bulk pHs in the US aqueous medium.