Ultrasound-enhanced membrane-cleaning processes applied water treatments: influence of sonic frequency on filtration treatments

Ultrasound (US) cleaning technique was applied to remove fouling of ultrafiltration (UF) and microfiltration (MF) membranes which were used to treat peptone and milk aqueous solutions, respectively. Membrane operations were performed by cross-flow filtration with 60 kPa operating pressure in an US field. The US employed had 28, 45 and 100 kHz frequency with 23 W/cm(2) output power. For each polymeric membrane made of polysulfone UF and cellulose MF, cleaning experiments were carried out with and without US after fouling. The fouled UF and MF membranes showed volume flux decline, but the membrane property was recovered by US irradiation. It was found in 28 kHz frequency that water cleaning was effective for recovery of declined condition due to fouling. Also, US-enhanced permeability of membranes was discussed in both membrane systems. We observed that US decreased the fouling condition in both membrane systems when US was irradiated before fouling. It was found that 28 kHz frequency US could enhance formation of the fouled layer in both filtration systems of peptone and milk solution.     

超声波对西施舌面盘幼虫生长率及成活率的影响

摘要实验室内用静水实验方法研究超声波对西施舌面盘幼虫生长速率、摄食率及成活率的影响。结果表明适宜条件超声辐射可提高面盘幼虫的生长速率和摄食率。在电功率为80w、频率20．4kHz条件下，超声辐射30s，幼虫日平均生长速率最快达13．67％，比对照组11．45％快2．22％。重复的超声辐射对幼虫的生长速率产生明显影响，第一次辐射后第1天各实验组面盘幼虫的生长速率都比对照组大，而辐射时间为50s实验组第1天生长速率最大达18．95％，比对照组10．23％提高8．72％。多次辐射幼虫生长速率明显减慢。     

Ultrasonic wave propagation in IIIrd group nitrides

The ultrasonic attenuation in hexagonal structured (wurtzite) third group nitrides (GaN, AlN and InN) has been evaluated at 300 K for an ultrasonic wave propagating along the unique axis of the crystal. Higher order elastic constants of these materials are calculated using the Lennard-Jones potential for the determination of ultrasonic attenuation. The ultrasonic velocity, Debye average velocity, thermal relaxation time and acoustic coupling constant are evaluated along the z-axis of the crystal using the second order elastic constants and other related parameters. The contributions of the elastic constants, thermal conductivity, thermal energy density, ultrasonic velocity and acoustic coupling constant to the total attenuation are studied. On the basis of the ultrasonic attenuation, it can be concluded that the AlN is more ductile than either GaN or InN at 300 K. Orientation dependent characterization has been achieved by calculation of the orientation dependent ultrasonic velocity, Debye average velocity and thermal relaxation time for the materials.     

A novel approach to quantitative ultrasonic naked gene delivery and its non-invasive assessment

The purpose of this study was to investigate practical, safe, easy-to-use, non-cytotoxic, and reliable parameters to apply to an ultrasound (US) naked gene therapy system. The ultrasound pressure at the point of cell exposure was measured using a calibrated hydrophone and the intensity calculated. An acoustic power meter calibrated using a hydrophone was used to measure the power of the transducer. Four cell types were exposed to US with different exposure times and intensities. Fluorescent microscopy, spectrophotometry, scanning electron microscope, laser scanning confocal microscopy, flow cytometry and histogram analysis were used to evaluate the results of the study. The plasmid of green fluorescent protein (GFP) served as the reporter gene. The energy accumulation E in US gene delivery for 90% cell survival was defined as the optimal parameters (E=3.56+/-0.06), and at 80% cell survival was defined as the damage threshold (E=59.67+/-3.54). US safely delivered GFP into S180 cells (35.1 kHz) at these optimal parameters without obvious damage or cytotoxity in vitro. Exposed cell function was proved normal in vivo. The transfection rate was 35.83+/-2.53% (n=6) in viable cells, corresponding to 90.17+/-1.47% (n=6) cell viability. The intensity of GFP expression showed a higher fluorescent peak in the group of adeno-associated virus GFP vector (AVV-GFP) than in the control group (P<0.001). The effect of US gene delivery and cell viability correlated as a fifth order polynomial with US intensity and exposure time. With optimal parameters, US can safely deliver naked a gene into a cell without damage to cell function. Both optimal uptake and expression of gene depend on the energy E at 90% cell survival. E can be applied as a control factor for bioeffects when combined with other parameters. Stable caviation results in optimal parameters for gene delivery and the transient caviation may cause cell damage, which will bring about a sharp rise of permeabilization. The results may be applied to the development of a novel clinical gene therapeutic system.     

Generation of very high pressure pulses at the surface of a sandwiched piezoelectric material

New clinical concepts in lithotripsy demand small shock heads. Reducing the size of piezoelectric shock heads will only be possible if the pressure generated at the surface of each transducer can be increased so that the total pressure at the focus remains very high. We propose for the first time to increase the pressure without increasing the transducer voltage by using sandwiched transducers, which are a combination of several stacked transducers. When excited at appropriate time intervals, the pressure waves generated by each one reinforce when they reach the load. This new technique has been successfully tested. A pressure of 2.5 MPa was generated with two stacked, 5 mm-thick 1-3 piezocomposite transducers operating at an excitation voltage of 8 kV. No transducer damage was detected after 10(6) shocks, which corresponds approximately to the treatment of 500 patients.     

Antioxidant,anti-lipidemic,hypoglycemic and antiproliferative effects of phenolics from Cortex Mori Radicis

Cortex Mori Radicis (CMR) is enriched in various phenolics, this study aimed to estimate the antioxidant effect, enzyme (lipase, α-amylase, α-glucosidase and acetyl-cholinesterase) inhibition and the anti-proliferative effect of the phenolic compounds in CMR. However, the amount of these compounds obtained from CMR is highly dependent on the processing conditions. In this study, the processing parameters of extracting the phenolics from CMR using ultrasonic technique pooled with high-speed shearing extraction (UTPHSE) were optimized. Subsequently, the phenolics from Cortex Mori Radicis (PCMR) were purified using AB-8 macroporous resin, and their chemical analysis, antioxidant, enzyme inhibition, and antiproliferative activities were studied. Based on our findings, the optimal parameters of UTPHSE were: L/S ratio 25.8:1 (mL/g), voltage 81.0 V, ultrasonic temperature 51.8 ℃ and ultrasonic time 289 s. And under the optimal extraction conditions, the extraction rate of the PCMR was 0.531 ± 0.004%. Compared with PCMR, the contents of “total phenolics, flavonoids, flavonols, flavanols and phenolic acids” increased 2.30, 2.67, 2.59, 3.63 and 2.72 times in the purified phenolics from Cortex Mori Radicis (PPCMR), respectively. In addition, PPCMR depicted significant DPPH, ABTS⁺ and superoxide anion radicals’ scavenging capability, reducing power, ferric ion reducing antioxidant power (FRAP) and remarkable inhibitory activities on “lipase, alpha-amylase, alpha-glucosidase, and the proliferation of HeLa, HepG2 and NCI-H460”. At the same time, the morphological changes of HeLa, HepG2 and NCI-H460 cells suggested that PPCMR could effectively inhibit the proliferation of tumor cells in vitro. Therefore, PPCMR have good potential as natural antioxidants, antilipidemic, hypoglycemic, and antineoplastic agents in functional foods and pharmaceuticals.     

Effect of reaction condition on microstructure and properties of (NiCuZn)Fe2O4 nanoparticles synthesized via co-precipitation with ultrasonic irradiation

Nano-spinel ferrites synthesized via chemical co-precipitation method are small in size and have serious agglomeration phenomenon, which makes separation difficult in the subsequent process. Ni_0.4Cu_0.2Zn_0.4Fe₂O₄ ferrites nanoparticles were synthesized via co-precipitation assisted with ultrasonic irradiation produced by ultrasonic cleaner with 20 kHz frequency using chlorinated salts and KOH as initial materials. The effects of ultrasonic power (0, 40 W, 60 W, 80 W) and reaction temperature on the microstructure and magnetic properties of ferrite nanoparticles were investigated. The structure analyses via XRD revealed the successful formation of pure (NiCuZn)Fe₂O₄ ferrites nanospinel without any impurity. The crystallites sizes were less than 40 nm and the lattice constant was near 8.39 Å. The TEM showed ferrite particle polygonal. M−H analyses performed the saturation magnetization and coercivity of ferrite nanoparticles obtained at the reaction temperature of 25℃ were higher than at 50℃ with same power. The samples exhibited the highest values of Ms 55.67 emu/g at 25℃ and 47.77 emu/g at 50℃ for 60 W and the lowest values of Hc 71.23 Oe at 25℃ for 40 W and 52.85 Oe at 50℃ for 60 W. The squareness ratio (SQR) were found to be lower than 0.5, which revealed the single magnetic domain nature (NiCuZn)Fe₂O₄ nanoparticles. All the outcomes show the ultrasonic irradiation has positive effects on improving the microstructure and increasing magnetic properties.     

Sonochemical effect and pore structure tuning of silica xerogel by ultrasonic irradiation of semi-solid hydrogel

Silica xerogels were prepared by the sol-gel method under ultrasonic irradiation, using tetraethylorthosilicate (TEOS) as the starting material. Hexamethyldisiloxane (HMDSO) was used as the hydrophobizing agent. When preparing silica xerogel, it is necessary to perform aging and hydrophobization to suppress shrinkage during ambient pressure drying, however, such treatments are time-consuming. In this study, the semi-solid hydrogel was irradiated with ultrasonic for the first time in order to accelerate aging and hydrophobic treatment, and the effect of ultrasonic frequency on structure was investigated. Firstly, ultrasonic irradiation was performed at frequencies of 100 kHz and 500 kHz, followed by hydrophobic treatment at a frequency of 500 kHz, in order to promote aging. The results identify optimum conditions for ultrasonic irradiation to promote aging and hydrophobization reactions, and it was found to be possible to prepare silica xerogels in less than 1/5 of the conventional time. The silica xerogels had a low density and the shrinkage was suppressed. In this study, it was found that ultrasonic irradiation of semi-solid hydrogel was very effective for promoting the reaction.     

Precise micro-particle and bubble manipulation by tunable ultrasonic bottle beams

This paper reports a method to generate tunable bottle beams using an ultrasonic lens, by which the bottle position can be precisely adjusted with the change of the acoustic frequency. Therefore, the position of a single particle or bubble in liquid can be manipulated without using phased array which is costly and huge with complex circuits. Furthermore, we introduced this method to multiple bubble manipulation using acoustic holography. The bottle properties against frequency are theoretically and experimentally analyzed. It is shown that the bottle position depends almost linearly on the operating frequency, which provides a basis for the precise manipulation of bubbles and particles. In addition, the relationship between the acoustic radiation force and the drag force under different incident acoustic pressures is considered, establishing a limit on the moving velocity of the trapped particles. The ultrasonic field observation is further demonstrated by Schlieren imaging system. The proposed method has potential biomedical applications, such as more flexible cell manipulation and targeted drug delivery in vivo, as well as potential applications in the study of chemical reactions between micro objects.     

Interaction of ultrasonic waves with structural damage: A diffraction analogy

This study investigates the interaction of ultrasonic waves and structural damage, i.e., cracking and corrosion. It is shown that cracking and corrosion damage produces a diffraction pattern that resembles that associated with the traditional physics of wave motion. The extension of this hypothesis implies that it may be possible to use a simple ripple tank to investigate how to best detect/sense and size a given damage state, e.g., corrosion. We also find that cracking, and corrosion damage, has a significant effect on both the amplitude and period of the waveform and also on the local (apparent) refractive index of the material and that these effects have the potential to be used as damage indicators.