Experimental study on killing tumor cells by activation of hematoporphyrin derivatives by bi-frequency focal ultrasound in vitro

Tumor cells K562 were killed by the hematoporphyrin derivatives (HpD) activated by bi-frequency focal ultrasound in which a choice of irradiating parameter of ultrasound was tested by experiment. The effect of killing tumor cells was investigated by MTT method and compared with the contrast group. The results showed that the bi-frequency ultrasound exhibited an improved effect of killing tumor cells than single frequency ultrasound. It was 2-3 times higher than the single frequency ultrasound for the killing effect of tumor cells. After the irradiation of ultrasound, the cell-killing effect of hatching 16 h is better than that of hatching 4 h in the hatching tank. This might be due to delay of cell apoptosis.     

Simple and inexpensive method for cryopreservation of fish sperm combining straw and powdered dry ice

Here, we propose a simple and inexpensive method for fish sperm cryopreservation. Sperm samples of the loach Misgurnus anguillicaudatus (Teleostei: Cobitidae) were diluted 7-fold by an extender containing 63.5 mM NaCl, 114 mM KCl, 20 mM Tris and 10% methanol. The cryogenic straws were placed in three kinds of self-made tubes which diameter was changed by commercially available materials and then immersed into powdered dry ice for 2 min and plunged into liquid nitrogen. This procedure resulted in a cooling rate at -421.4 +/- 119.84 (control), -55.8 +/- 4.32 (tube 1), -40.2 +/- 3.43 (tube 2) and -33.3 +/- 2.09 C/min (tube 3). In the slowest cooling rate by the tube 3, total motility (72 +/- 3 %), duration (146 +/- 12 s) and hatching rates (29 +/- 04 %) were higher than those by other rates. Progressive motility (83 +/- 5 %) did not differ significantly from fresh samples.     

2D-PIV analysis of loach motion and flow field

The propulsion methods of the aquatic lives are the results of optimization by evolution and are useful for the design of swimming-robot, etc. Among them, loach has unique propulsion technique both bending its long body and shaking caudal fin. Our purpose of the research is to clarify its swimming mechanism through flow field analysis. Two dimensional motion and flow around it have been experimentally visualized by particle image velocimetry (PIV). Vortices around a loach and the interactions between the loach body and surrounding water are analyzed. Generating and growing vortices by bending its body, it pushes water backward to gain repulsing force, and it seems that moves through vortices reducing the resistance force at the same time. When a vortex reaches to the caudal fin, it accelerates both sides of the vortex pushing water backward and seems gaining propulsion utilizing the caudal fin. After moving forward, loach leaves a vortex street like reverse Karman vortices, which means that loach gains propulsion.     

Effects of multi-frequency ultrasound on freezing rates and quality attributes of potatoes

The effects of multi-frequency ultrasound assisted freezing on the freezing rate, microstructure, quality properties (drip loss, firmness, total calcium content, l-ascorbic acid content and total phenol content) of potatoes were studied. The results indicated that the freezing effects of multi-frequency ultrasound was better than those of single-frequency ultrasound. Multi-frequency ultrasound could significantly increase the freezing rate and preserve the quality of frozen samples better. With increase in the number of ultrasonic frequencies, the freezing effect was more obvious. In addition, scan electron microscopy (SEM) images showed that the ice crystals formed by the multi-frequency ultrasonic treatment were fine and uniformly distributed, which caused less damage to the frozen potato samples. From the analysis of the quality attributes, the nutritional values of the samples after multi-frequency ultrasonic treatment was higher, but attention should be paid to the negative influence of the hydroxyl radical generated by the multi-frequency ultrasound.     

Study on permeability of DMSO in embryos of red seabream (Pagrus major) by capillary electrophoresis

The objectives were to investigate the permeability of DMSO to red seabream (Pagrus major) embryos by capillary electrophoresis and the effects of DMSO concentrations (5 to 40 percent, volume basis) and immersion times (10, 30 and 60 min) on hatching rate and morphology. The results suggested the internal DMSO concentrations were positively related with the external concentrations and exposure times, while the hatching rate was negatively related. The hatching rate decreased drastically (less than 50 percent) after exposure in 35 percent, 20 percent and 15 percent DMSO for over 10, 30 and 60 min, respectively. In all groups, when hatching rate was greater 50 percent, the internal DMSO concentration was less than 2 percent, which was still insufficient for successful cryopreservation. Morphological changes indicated the chorion was permeable to the cryoprotectant. A sign of dehydration in yolk were observed, for a significant decrease in the maximal yolk sac diameter. However, further research was needed to investigate whether the DMSO permeated into the yolk.     

In vitro ultrasonic heating of fetal bone

The temperature increase measured in vitro in human fetal femurs exposed to 1 MHz, continuous wave ultrasound at 37 degrees C is reported. The temperature is measured with a thermocouple probe and is given for several gestational ages. The initial rate of the temperature increase in the specimens is evaluated and compared to known values of absorption in soft tissue. For example, the initial rate of temperature increase in the 108-day gestational age specimen resulting from exposure to ultrasound is 30 times greater in the fetal bone than that of soft tissue with an absorption coefficient of 0.05 cm-1.     

超声波对丰年虫卵孵化的影响

研究了固定频率和强度的超声波对饵料生物丰年虫卵（ｃｈｉｒｏｃｅｐｈａｌｕｓ）化的影响。实验结果表明,在适宜的超声波辐照下,丰年虫卵的孵化率比对照组提高８％,孵化时间提前２ｈ。     

The effect of a 7 T magnetic field on the egg hatching of Heliothis virescens

The effect of a strong magnetic field on the egg hatching of Heliothis virescens (Tobacco bugworm) in a 7 Tesla field was studied, and apparent biological effects of the magnetic field were observed. On average of three batches of eggs in this study, the hatching of the eggs in the 7 T field was delayed about 21.7 ± 0.9 h and the hatching rate was reduced to about 58 ± 8% compared to those of eggs in 1.4 Gauss field. No apparent effect of the 1600 Gauss fringe field of the 7 T magnet on the egg hatching of Heliothis virescens was observed.     

Ultrasonic reactivation of phosphonate poisoned calcite during crystal growth

The effect of ultrasonic irradiation (42,150 Hz, 17 W dm(-3)/7.1 W cm(-2)) on the growth of calcite in the presence of the inhibitor nitrilotris(methylene phosphonic acid) (NTMP) was investigated at constant composition conditions. In seeded growth experiments, it was found that the inhibiting effect of NTMP on crystal growth could be seriously mitigated under influence of ultrasonic irradiation. An approximately twofold increase in volumetric growth rate was achieved during ultrasonic irradiation, and recovery of the growth rate following inhibition was strongly enhanced compared to growth experiments without ultrasonic irradiation. The results could be explained in part by the physical effect of ultrasound that causes breakage and attrition of poisoned crystals, which resulted in an increase in fresh surface area. Mass spectroscopy analysis of sonicated NTMP solutions revealed that there is also a chemical effect of ultrasound that plays an important role. Several breakdown products were identified, which showed that ultrasound caused the progressive loss of phosphonate groups from NTMP, probably by means of physicochemically generated free radicals and/or pyrolysis in the hot bubble-bulk interface.     

The development and evaluation of ultrasound for the treatment of bacterial suspensions. A study of frequency,power and sonication time on cultured Bacillus species

Some species of bacteria produce colonies and spores which agglomerate in spherical clusters (Bacillus subtilis) and this serves as a protection for the organisms inside against biocidal attack. Flocs of fine particles e.g. clay can entrap bacteria which can also protect them against the biocides. It is because of problems such as these that alternative methods of disinfecting water are under active investigation. One such method is the use of power ultrasound, either alone or in combination with other methods. Ultrasound is able to inactivate bacteria and deagglomerate bacterial clusters or flocs through a number of physical, mechanical and chemical effects arising from acoustic cavitation. The aim of this study was to investigate the effect of power ultrasound at different powers and frequencies on Bacillus subtilis. Viable plate count techniques were used as a measure of microbial activity. Results showed a significant increase in percent kill for Bacillus species with increasing duration of exposure and intensity of ultrasound in the low-kilohertz range (20 and 38 kHz). Results obtained at two higher frequencies (512 and 850 kHz) indicated a significant increase in bacteria count suggesting declumping. In assessing the bacterial kill with time under different sonication regimes three types of behaviour were characterized:

• High power ultrasound (lower frequencies) in low volumes of bacterial suspension results in a continuous reduction in bacterial cell numbers i.e. the kill rate predominates.

• High power ultrasound (lower frequencies) in larger volumes results in an initial rise in cell numbers suggesting declumping of the bacteria but this initial rise then falls as the declumping finishes and the kill rate becomes more important.

• Low intensity ultrasound (higher frequencies) gives an initial rise in cell numbers as a result of declumping. The kill rate is low and so there is no significant subsequent decrease in bacterial cell numbers.

     

Curing properties of furfuryl alcohol condensate with carbonaceous fine particles under ultrasonication

Ultrasonic treatment (sonication) was carried out through the curing process of furan resin by using an ultrasonic homogenizer at the frequency of 20 kHz and the various intensities (0-90 W). Various carbonaceous fine particles were added to furan resin to investigate the change of polymerization degree. The curing rate of furan resin was accelerated by sonication, which increased the polymerization degree with an increase in ultrasound intensity. The increase of curing rate was also observed by small additions of carbonaceous fine particles. In this case, the curing rate was increased with an increase in the specific surface area on additives.     

Ultrasonic enhancement of the supercritical extraction from ginger

This work examines the concurrent use of power ultrasound during the extraction of pungent compounds from a typical herb (ginger) with supercritical CO₂. A power ultrasonic transducer with an operating frequency of 20 kHz is connected to an extraction vessel and the extraction of gingerols from freeze-dried ginger particles (4–8 mm) is monitored. In the presence of ultrasound, we find that both the extraction rate and the yield increase. The higher extraction rate is attributed to disruption of the cell structures and an increase in the accessibility of the solvent to the internal particle structure, which enhances the intra-particle diffusivity. While cavitation would readily account for such enhancement in ambient processes, the absence of phase boundaries should exclude such phenomena above the critical point. Possible alternate mechanisms for the cell structure damage are discussed.     

Ultrasound accelerated esterification of bile acids

In this study power ultrasound accelerated esterification reactions of some model substances and bile acids were done. In the model reactions the best result was 19-fold increase in the reaction rate when using ultrasound and the temperature was allowed to rise during the irradiation. In the case of bile acid methyl esters a clear increase in the reaction rates was also observed by ultrasonic irradiations.     

Effects of removal of necrotic blastomeres from human cryopreserved embryos on pregnancy outcome

This study assessed whether the implantation potential of embryos that were partially damaged after freezing and thawing can be improved by removal of necrotic blastomeres. We retrospectively analyzed the pregnancy rate and implantation rate of 170 human frozen embryo transfer cycles. Laser-assisted hatching and micromanipulation were performed to remove the necrotic blastomeres. A higher clinical pregnancy rate (22.22%) and embryo implantation rate (10.17%) were observed when transferred embryos comprised fully intact and partially damaged embryos compared with partially damaged embryos alone (5.88% and 2.82%, respectively). When transferred embryos were fully intact and partially damaged embryos, removal of necrotic blastomeres from partially damaged embryos significantly increased the clinical pregnancy rate (43.90% versus 24.00%, P<0.05) and the implantation rate (19.44% versus 10.29%, P<0.05). The results indicated that the implantation potential of partially damaged cryopreserved embryos can be improved by removal of necrotic blastomeres with laser-assisted hatching and micromanipulation.     

Intensified dissolution of uranium from graphite substrate using ultrasound

Decontamination of graphite structural elements and recovery of uranium is crucial for waste minimization and recycle of nuclear fuel elements. Feasibility of intensified dissolution of uranium-impregnated graphite substrate using ultrasound has been studied with objective of establishing the effect of operating parameters and the kinetics of sonocatalytic dissolution of uranium in nitric acid. The effect of operating frequency and acoustic intensity as well as the acid concentration and temperature on the dissolution of metal has been elucidated. It was observed that at lower acid concentrations (6 M–8 M), the dissolution ratio increases by 15% on increasing the bath temperature from 45 to 70 °C. At higher acid concentration (>10 M), the increase was only around 5–7% for a similar change in temperature. With 12 M HNO₃, pitting was also observed on the graphite surface along with erosion due to high local reaction rates in the presence of ultrasound. For higher frequency of applied ultrasound, lower dissolution rate of uranium was observed though it also leads to high rates of erosion of the substrate. It was thus established that suitable optimization of frequency is required based on the nature of the substrate and the choice of recycling it. The dissolution rate was also demonstrated to increase with acoustic intensity till it reaches to the maximum at the observed optimum (1.2 W/cm² at 33 kHz). Comparison with silent conditions revealed that enhanced rate was obtained due to the use of ultrasound under optimum conditions. The work has demonstrated the effective application of ultrasound for intensifying the extent of dissolution of metal.     

The effect of ultrasound upon the oxidation of thiosulphate on stainless steel and platinum electrodes

Ultrasound was found to increase the oxidation peak current and hence the decomposition rate of thiosulphate 50-fold compared to silent conditions. The effects of the ultrasonic frequency (20 and 38 kHz) and power upon the electrochemical oxidation of thiosulphate in aqueous KCl (1 mol dm-3) at stationary stainless steel and platinum electrodes were studied chronoamperometrically and potentiostatically (at various scan rates). No sigmoidal-shaped voltammograms were observed for the redox couple S4O6(2-)/S2O3(2-) in the presence of ultrasound. However, application of ultrasound to this redox couple provided an increase in the oxidation peak current at the frequencies employed, the magnitude of which varied with concentration, scan rate and ultrasonic power. Under sonication at 20 and 38 kHz, the oxidation peak potential shifted anodically with increasing ultrasonic power. This anodic shift in potential may be due to the formation of hydroxyl radicals, changes in electrode surface composition and complex adsorption phenomena. The large increase in oxidation peak currents and the rates of decomposition of thiosulphate, in the presence of ultrasound, are explained in terms of enhanced mass transfer at the electrode due to cavitation and acoustic streaming together with microstreaming coupled with adsorption phenomena. It is also shown that changes in macroscopic temperature throughout the experiment are insufficient to cause the observed enhanced diffusion.     

Ultrasonic frequency effects on the removal of Microcystis aeruginosa

Algae bloom in source water causes high chemical consumption and deteriorates water quality in waterworks. This paper studied the ultrasonic removal of Microcystis aeruginosa. The results showed that algae cells could be effectively removed by sonication and gas vesicle collapse was the main mechanism. The ultrasonic algae removal followed the first order reaction with a rate constant of 0.023 min(-1) (80 W, 80 kHz). Higher ultrasound frequency benefited algae removal; the algae removal rate constant was 0.114 min(-1) at 1320 kHz and 0.0224 min(-1) at 20 kHz (80 W). Higher ultrasound power also accelerated algae removal; the algae removal rate constant was 0.023 min(-1) at 80 W and 0.007 min(-1) at 32 W (80 kHz). However, high ultrasound power and long irradiation caused microcystins to increase. 80 W, 80 kHz sonication for 5 min increased the extracellular microcystins concentration from 0.87 microg/L to 3.11 microg/L. Sound frequency had little impact on the microcystins release. The chlorophyll a concentration initially decreased and then stabilized after 5 min of sonication.     

Electrochemical study of silver thiosulphate reduction in the absence and presence of ultrasound

The electrochemical reduction of silver thiosulphate was studied potentiostatically on platinum electrodes in the absence and presence of ultrasound (20 kHz). This system is irreversible and the reaction is both diffusion and kinetically controlled. The slowest step is the kinetic reaction especially the chemisorption of ions at the electrode surface. Ultrasound greatly improves the mass transport, which can be explained by changing from diffusion to mainly convection. This paper reports the effect of ultrasound upon electrode kinetic and mass-transport parameters at various RDE rotation speeds and ultrasonic intensities. It was found that the heterogeneous rate constant (kf) is improved in the presence of ultrasound due to the increase in the formal or standard heterogeneous rate constant (k0) (approximately by 10-fold under sonication).     

Ultrasonic inactivation of Bacillus alpha-amylase. I. effect of gas content and emitting face of probe

Sonoinactivation of alpha-amylase from Bacillus amyloliquefacience was studied at a constant frequency of 30 kHz. The effect of sonotrode emitting face and gas content of medium on the efficiency of enzyme inactivation were investigated at different time-temperature combinations and generation of OH free radicals was also monitored. The results showed that ultrasound effectively inactivated alpha-amylase with a minimum overall inactivation rate at 50 degrees C. The tip diameter of the sonotrode and the gas content of the medium both significantly affected the rate of enzyme inactivation. The increase of tip diameter increased the effect of ultrasound on the enzyme, while the removal of dissolved gas adversely influenced the cavitational events and reduced the rate of enzyme inactivation. Calculation of the kinetic and activation parameters revealed that ultrasound decreased the activation energy, E(a), activation enthalpy, DeltaH(#), and the activation Gibbs free energy, DeltaG(#), and strongly reduced the activation entropy, DeltaS(#), down to negative values. This huge reduction in activation entropy was attributed to the different mechanisms of inactivation induced by heat and ultrasound. It is proved in this study that ultrasonically generated OH free radicals and shear forces, which arise from pulsation- or collapse of bubbles, both can destabilize the enzyme, although their contribution to the overall inactivation varies depending on the temperature and the tip diameter of the sonotrode.     

Ultrasonically assisted drying of fine particles

An investigation was made to determine the increase in drying rate which could be obtained through the addition of ultrasound to low temperature drying of heat sensitive fine particles. Airbourne ultrasound having a frequency of 20 kHz with intensities up to 155 dB was used. The materials dried included fine, sulphur-free powder coal, plastics powders, and neutralized acid mine drainage sludge. The limitations of the use of ultrasound in assisting drying were also studied. Theories are proposed to explain both the ultrasonic enhancement of drying and the limitations found.