Effect of ruptured cavitated bubble cluster on the extent of the cell deformation by ultrasound

In this paper, the bubble-cell model is presented. The effects of the spacing between the bubble population and the cell, the radius of the bubble and the bubble medium on the degree of cell deformation were investigated by solving the Helmholtz equation and the equilibrium of motion equation using COMSOL Multiphysis@ software. The ultrasonic transducer is applied in a round bottom flask with the bubble-cell model on the side of the ultrasonic transducer. When the distance between the bubble cluster and the cell gradually increases, the extent of deformation of the cell is reflected as first increasing and then decreasing, reaching the maximum deformation at D = 2. When the radius of the bubble is changed, there is a “constant frequency” at low frequency ultrasound in any distance case, at which the cell deformation will be violent. However, when the bubble medium is changed, there is no significant change in the degree of deformation of the cells. In other words, changes in the structure of the bubble-cell model affect the degree of cell deformation, but without structural changes, the degree of cell deformation changes very little.     

A new approach for the large-scale generation of mature dendritic cells from adherent PBMC using roller bottle technology

Background  

Human monocyte-derived DC (mDC) loaded with peptides, protein, tumor cell lysates, or tumor cell RNA, are being tested as vaccines against multiple human malignancies and viral infection with great promise. One of the factors that has limited more widespread use of these vaccines is the need to generate mDC in large scale. Current methods for the large-scale cultivation of mDC in static culture vessels are labor- and time- intensive, and also require many culture vessels. Here, we describe a new method for the large-scale generation of human mDC from human PBMC from leukopheresis or buffy coat products using roller bottles, never attempted before for mDC generation. We have tested this technology using 850 cm² roller bottles compared to conventional T-175 flat-bottom static culture flasks.     

Influence of ultrasonic in low thermal expansion Fe-Ni electrodeposition process for micro-electroforming

The electrochemical mechanism of Fe-Ni electrodeposition under ultrasonic was investigated by electrochemistry methods. Linear scanning voltammetry and cyclic voltammetry were used to show that the deposition process changed from the diffusion control under static conditions to an electrochemical control under ultrasonic conditions. Chronoamperometry curves showed that the Fe-Ni deposit occurred by a mechanism that instantaneous nucleation is followed by three-dimensional growth under charge transfer control. Chronopotentiogram indicated that because of the intensity of the ultrasound stripping effect, high ultrasonic power is unsuitable for electroforming Fe-Ni alloy, and a high current density is also not appropriate. Thus, the optimum parameters for Fe-Ni electrodeposition under ultrasonic conditions are ultrasonic power between 80 and 100 W (power density 0.28–0.35 W/cm²), and a current density lower than 10 mA/cm² with temperature 323 K and pH 3. Experiments were performed to verify that the Fe-Ni masks prepared by ultrasonic-assisted electroforming had a good surface quality. The increase in ultrasonic power can obtain a larger grain size, thus got a low thermal expansion coefficient and a high hardness. Therefore, ultrasonic-assisted electrodeposition technology provides an effective and practically feasible manufacturing method for OLED Fe-Ni mask preparation.     

Frequency and power dependence of ultrasonic degassing

We investigated the time variation of ultrasonic degassing for air-saturated water and degassed water with a sample volume of 100 mL at frequencies of 22, 43, 129, 209, 305, 400, 514, 1018, and 1960 kHz and ultrasonic power of 15 W. Ultrasonic degassing was evaluated by dissolved oxygen concentration. Ultrasonic degassing was also investigated at a frequency of 1018 kHz and ultrasonic powers of 5, 10, 15, and 20 W. The dissolved oxygen concentration varied with the ultrasonic irradiation time and became constant after prolonged ultrasonic irradiation. The constant dissolved oxygen concentration value depended on the frequency and ultrasonic power but not the initial dissolved oxygen concentration. The degassing rate at 101.3 kPa was higher in the frequency range of 200 kHz to 1 MHz. The frequency dependence of the degassing rate was almost the same as that of the sonochemical efficiency obtained by the potassium iodide (KI) method. Ultrasonic degassing in the frequency range of 22–1960 kHz was also investigated under reduced pressure of 5 kPa. Degassing was accelerated when ultrasonic irradiation was applied under reduced pressure. However, under a reduced pressure of 5 kPa, the lower the frequencies, the higher is the degassing rate. The sonochemical reaction rate was examined by the KI method for varying dissolved air concentrations before ultrasonic irradiation. Cavitation did not occur when the initial dissolved oxygen concentration was less than 2 mg·L⁻¹. Therefore, the lower limit of ultrasonic degassing under 101.3 kPa equals 2 mg·L⁻¹ dissolved oxygen concentration. A model equation for the time variation of dissolved oxygen concentration due to ultrasonic irradiation was developed, and the degassing mechanism was discussed.     

Physical field simulation of the ultrasonic radiation method: An investigation of the vessel,probe position and power

In this paper, the effects of ultrasonic probe position, vessel shape, and ultrasonic input power on the sound pressure distribution in the reactor were investigated by solving the Helmholtz equation using COMSOL Multiphysis^@ software. Three different types of glass containers were used in the study, which are beaker, Erlenmeyer flask, and round bottom flask. The maximum value of sound pressure in the three containers will gradually increase when the distance between the probe and the bottom of the container decreases. When the distance decreases, the area of the high acoustic pressure region in the round bottom flask does not change significantly, while the area of the high acoustic pressure region in the beaker and Erlenmeyer flask increases sharply, which means that the use of the round bottom flask can reduce the influence of the dead zone on the preparation of nanomaterials. In addition, the change in power increases the value of the peak negative acoustic pressure in the vessel, enhancing the response efficiency of ultrasonic cavitation.     

Ultrasonic radiation to enable improvement of direct methanol fuel cell

To improve DMFC (direct methanol fuel cell) performance, a new method using ultrasonic radiation is proposed and a novel DMFC structure is designed and fabricated in the present paper. Three ultrasonic transducers (piezoelectric transducer, PZT) are integrated in the flow field plate to form the ultrasonic field in the liquid fuel. Ultrasonic frequency, acoustic power, and methanol concentration have been considered as variables in the experiments. With the help of ultrasonic radiation, the maximum output power and limiting current of cell can be independently increased by 30.73% and 40.54%, respectively. The best performance of DMFC is obtained at the condition of ultrasonic radiation (30 kHz and 4 W) fed with 2 M methanol solution, because both its limiting current and output power reach their maximum value simultaneously (222 mA and 33.6 mW, respectively) under this condition. These results conclude that ultrasonic can be an alternative choice for improving the cell performance, and can facilitate a guideline for the optimization of DMFC.     

Scale-up disaggregation of palygorskite crystal bundles via ultrasonic process for using as potential drilling fluid

High-efficient disaggregation of palygorskite (PAL) crystal aggregates into individual nanorods is the key to exploiting its nanometer properties, which remains a challenge at present. The sonochemical cavitation effects have been successfully employed for the intensification of physical and chemical processing applications, but it still lacks the relevant study on the scale-up disaggregation of PAL crystal bundles. Here, the energy-efficient, scale-up ultrasonic process was developed to disaggregate PAL aggregates in batches, and the effects of ultrasonic treatment time, temperature, and power on physicochemical features of PAL were systematically investigated. The results showed that the single dispersed PAL nanorods could be continuously produced by sonicating 15 wt% of PAL suspension at 20 kHz, 2000 W and 30 °C for 5 min retaining the original nanorod length and layered-chain structure. It also greatly improved the dispersion of nanorod crystal, specific surface area and suspension stability of PAL. The ultrasonically disaggregated PAL has a higher pulping rate in water (14.96 m³/t) and saturated NaCl system (14.45 m³/t), which is significantly better than that of natural PAL in water (14.72 m³/t) and saturated NaCl solution (12.37 m³/t). It suggests that the disaggregated PAL exhibits excellent potential and adaptability as a viscosity enhancer for drilling fluid. Therefore, this work provides a feasible and efficient ultrasonic process for large-scale industrialized disaggregation of PAL crystal bundles, laying a foundation for the high-value utilization of natural PAL as one-dimensional nanomaterials.     

A facile sonochemical route for the synthesis of MoS2/Pd composites for highly efficient oxygen reduction reaction

For the alkaline fuel cell cathode reaction, it is very essential to develop novel catalysts with superior catalytic properties. Here, we report the synthesis of highly active and stable MoS₂/Pd composites for the oxygen reduction reaction (ORR), via a simple, eco-friendly sonochemical method. The bulk MoS₂ was first transformed into single and few layers MoS₂ nanosheets through ultrasonic exfoliation. Then the exfoliated MoS₂ nanosheets served as supporting materials for the nucleation and further in-situ growth of Pd nanoparticles to form MoS₂/Pd composites via ultrasonic irradiation. Cyclic voltammetry and rotating disk voltammetry measurements demonstrate that as-prepared MoS₂/Pd composites which provides a direct four-electron pathway for the ORR, have better electrocatalytic activity, long-term operation stability than commercial Pt/C catalyst. We expect that the present work would provide a promising strategy for the development of efficient oxygen reduction electrocatalyst. In addition, this study can also be extended to the preparation of other hybrid with desirable morphologies and functions.     

Ultrasonic intensity microscopy for imaging of living cells

Ultrasound intensity microscopy was developed for in vivo imaging. This paper describes the preliminary results obtained using 300 MHz ultrasound intensity microscopy for in vitro characterization of cell cultures. The novelty of the approach lies in the fact that it allows remote, non-contact and disturbance-free imaging of cultured synovial cells and the changes in the cells’ properties due to external stimulants such as transforming growth factor beta-1 (TGF-β1). The intensity imaging method has potential for extracting mechanical cell properties and monitoring the effects of drugs.Ultrasound propagates through a thin specimen such as cultured cells and is reflected at the interface between the specimen and substrate. A two-dimensional distribution of the ultrasonic intensity, which is closely related to the mechanical properties, is visualized to analyze cell organs, such as the nucleus at the central part and the cytoskeleton at the peripheral zone. After stimulation with TGF-β1, the ultrasonic intensity at the actin zone was significantly increased compared with the control.     

Medium-high frequency sonication dominates spherical-SiO2 nanoparticle size

Spherical SiO₂ nanoparticles (SSNs) have been inventively synthesized using the Stöber method with sonication at medium–high frequencies (80, 120, and 500 kHz), aiming to control SSN size and shorten reaction time. Compared to the conventional method, such sonication allowed the Stöber reaction complete in 20–60 min with a low molar ratio of NH₄OH/tetraethyl orthosilicate (0.84). The hydrodynamic diameters of 63–117 nm of SSNs were obtained under sonication with 80, 120, and 500 kHz of ultrasonic frequencies. Moreover, the SSNs obtained were smaller at 120 kHz than at 80 kHz in a multi-frequencies ultrasonic reactor, and the SSN size decreased with increasing ultrasonic power at 20 °C, designating the sonochemical unique character, namely, the SSN-size control is associated with the number of microbubbles originated by sonication. With another 500 kHz ultrasonic bath, the optimal system temperature for producing smaller SSNs was proven to be 20 °C. Also, the SSN size decreased with increasing ultrasonic power. The smallest SSNs (63 nm, hydrodynamic diameter by QELS, or 21 nm by FESEM) were obtained by sonication at 207 W for 20 min at 20 °C. Furthermore, the SSN size increased slightly with increasing sonication time and volume, favoring the scale-up of SSNs preparation. The mechanisms of controlling the SSN size were further discussed by the radical’s role and effects of ammonia and ethanol concentration.     

Preparation and luminescence of (SBA-15)–Eu2O3 composite materials

In this study, (SBA-15)–Eu₂O₃ host-guest composites have been prepared with SBA-15 mesoporous sieve as host and Eu₂O₃ as guest via the solid-phase ultrasonic method and liquid-phase medium ultrasonic method. The host–guest composite materials showed the properties of luminescence. Four excitation peaks appeared in the excitation spectra of the samples. The excitation peaks are located at 397, 415, 466, 537 nm; 392, 408, 464, 532 nm and 393, 406, 465, 533 nm for the nano-Eu₂O₃, the liquid-phase medium ultrasonic method (LPMUM) and the solid-phase ultrasonic method (SPUM) samples, respectively. SBA-15 has the well-ordered hexagonal arrays of mesopores, which makes centrosymmetry of Eu³⁺ higher in the prepared (SBA-15)–Eu₂O₃ samples. The intensity of ⁵D₀→⁷F₁ transition strengthens, and the intensity of ⁵D₀→⁷F₂ transition weakens.     

超声波光生物制氢反应器启动及产氢特性

实验研究了超声波光生物制氢反应器的启动工艺以及反应器的产氢特性,探讨了超声时间和超声功率对反应器产氢性能的影响。超声波光生物反应器的启动实验进行了96 h,此时反应器光合细菌生物量和反应液pH值趋于稳定,启动完成。在系统稳定运行后,随着超声时间、超声功率的增大,超声波光生物制氢反应器的产氢速率和产氢得率呈先增加后降低的趋势,然而葡萄糖去除率却随着超声时间的增加而增大。     

Iron-dependent formation of reactive oxygen species and glutathione depletion after accumulation of magnetic iron oxide nanoparticles by oligodendroglial cells

Magnetic iron oxide nanoparticles (IONP) are currently used for various neurobiological applications. To investigate the consequences of a treatment of brain cells with such particles, we have applied dimercaptosuccinate (DMSA)-coated IONP that had an average hydrodynamic diameter of 60 nm to oligodendroglial OLN-93 cells. After exposure to 4 mM iron applied as DMSA–IONP, these cells increased their total specific iron content within 8 h 600-fold from 7 to 4,200 nmol/mg cellular protein. The strong iron accumulation was accompanied by a change in cell morphology, although the cell viability was not compromized. DMSA–IONP treatment caused a concentration-dependent increase in the iron-dependent formation of reactive oxygen species and a decrease in the specific content of the cellular antioxidative tripeptide glutathione. During a 16 h recovery phase in IONP-free culture medium following exposure to DMSA–IONP, OLN-93 cells maintained their high iron content and replenished their cellular glutathione content. These data demonstrate that viable OLN-93 cells have a remarkable potential to deal successfully with the consequences of an accumulation of large amounts of iron after exposure to DMSA–IONP.     

Design of a novel bioreactor and application in vascular tissue engineering

Endothelial cells (ECs) detachment under high shear stress at the early period of transplantation resulted in thrombosis and occlusion. To solve this problem, we developed a novel bioreactor. The bioreactor mimicked the formation of pulsatile flow in physiological conditions. Human umbilical vein ECs were seeded onto the lumen of living tissue conduits grown within dog peritoneal cavity. The shear stress generated by the bioreactor was increased step by step from 1.5 ± 0.8 dyn/cm² to 5.3 ± 2.4 dyn/cm², and was applied to ECs after static culture for 2 days. The results showed that completely confluent monolayer ECs were elongated, and were oriented parallel to the flow direction. The bioreactor could provide good environment for formation of endothelium. Stepwise increase shear stress could strengthen cell-cell and cell-extracellular matrix. The flow conditions of the bioreactor play a key role to determine the quality of the ECs lining.     

Effect of switching ultrasonic amplitude in preparing a hybrid of fullerene (C60) and gallium oxide (Ga2O3)

In this study, we proposed ‘switching ultrasonic amplitude’ as a new strategy of applying ultrasonic energy to prepare a hybrid of buckminsterfullerene (C₆₀) and gallium oxide (Ga₂O₃), C₆₀/Ga₂O₃. In the proposed method, we switched the ultrasonic amplitude from 25% to 50% (by 5% amplitude per 10 min, within 1 h of ultrasonic irradiation) for the sonochemical treatment of a heterogeneous aqueous mixture of C₆₀ and Ga₂O₃ by a probe-type ultrasonic horn operating at 20 kHz. We found that compared to the conventional techniques associated with high amplitude oriented ultrasonic preparation of functional materials, switching ultrasonic amplitude can better perform in preparing C₆₀/Ga₂O₃ with respect to avoiding titanium (Ti) as an impurity generating from the tip erosion of a probe-type ultrasonic horn during high amplitude ultrasonic irradiation in an aqueous medium. Based on SEM/EDX analysis, the quantity of Ti (wt.%) in C₆₀/Ga₂O₃ prepared by the proposed technique of switching ultrasonic amplitude was found to be 1.7% less than that prepared at 50% amplitude of ultrasonic irradiation. The particles of C₆₀/Ga₂O₃ prepared by different modes of amplitude formed large (2–12 μm) aggregates in their solid phase.Whereas, in the aqueous medium, they were found to disperse in their nano sizes. The minimum particle size of the as-synthesized C₆₀/Ga₂O₃ in an aqueous medium prepared by the proposed method of switching ultrasonic amplitude reached to approximately 467 nm. Comparatively, the minimum particle sizes were approximately 658 nm and 144 nm, using 25% and 50% amplitude, respectively. Additionally, Ga₂O₃ went under hydration during ultrasonic irradiation. Moreover, due to the electron cloud interference from C₆₀ in the hybrid structure of C₆₀/Ga₂O₃, the vibrational modes of Ga₂O₃ were Raman inactive in C₆₀/Ga₂O₃.     

Removal of field-collected Microcystis aeruginosa in pilot-scale by a jet pump cavitation reactor

Hydrodynamic cavitation has been investigated extensively in the field of water treatment in the last decade and a well-designed hydrodynamic cavitation reactor is critical to the efficient removal of algal and large-scale application. In this paper, a jet pump cavitation reactor (JPCR) is developed for the removal of cyanobacteria Microcystis aeruginos in a pilot scale. The results demonstrate that the photosynthetic activity of M. aeruginosa is greatly inhibited immediately after treatment in the JPCR, and the growth is also hindered after 3 days culture. Moreover, a high cell disruptions of M. aeruginosa is detected after treated by JPCR. The release of chlorophyll-a indicates that the JPCR caused serious rupture to M. aeruginosa cells. The plausible cell disruption mechanisms are proposed in accordance with a fluorescence microscope and scanning electron microscope. Then, the optimization of cell disruption efficiency is also investigated for various operating conditions. The results showed that the algal cell disruption efficiency is improved at higher inlet pressure and the cavitation stage between the unstable limited operation cavitation stage and stable limited operation cavitation stage. The effect and optimization of JPCR on algal reduction are highlighted. The results of the study promote the application of hydrodynamic cavitation on algal removal and provide strong support for JPCR application in algal removal.     

Effect of citric acid induced deflocculation on the ultrasonic pretreatment efficiency of dairy waste activated sludge

In this investigation, the application of citric acid was explored for the removal of extracellular polymeric substance (EPS) from waste activated sludge (WAS), followed by ultrasonic pretreatment, which enhanced the subsequent anaerobic biodegradability. EPS was removed with 0.05 g/g SS of citric acid. The chemical oxygen demand (COD) solubilization and suspended solids (SS) reduction that occurred for specific energy input of 171.9 kJ/kg TS, in deflocculated (EPS removed and ultrasonically pretreated) sludges were found to be 22.70% and 20.28% and was comparatively higher, than the flocculated (with EPS and ultrasonically pretreated). The biogas yield potential of flocculated and deflocculated sludges (specific energy input – 171.9 kJ/kg TS) was found to be 0.212 L/(g VS) and 0.435 L/(g VS), respectively. Accordingly, the deflocculation and ultrasonic pretreatment improved the anaerobic biodegradability efficiently. Thus, this chemo mediated sonic pretreatment is an effective method for enhancing biodegradability and improving clean energy generation from WAS.     

Lactobacillus plantarum-derived biosurfactant: Ultrasound-induced production and characterization

The aim of the present study was to investigate the effect of ultrasonic treatment (25 kHz) on biosurfactant production by Lactobacillus plantarum ATCC 8014. The impacts of the ultrasonication (with a frequency of 25 kHz and power of 7.4 W for 30 min time duration) were examined at different stages of the fermentation process to obtain the optimum stimulation instant(s). The optimum scenario was found to be one-time sonication at the 12^th hour of fermentation which can be beneficial from an economic point of view (compared with multiple applications of sonication). Ultrasonic treatment at this time resulted in enhancement of the productivities of biomass (4.5 g/L) and biosurfactant (2.01 g/L) which was almost 1.3 times higher than those of the non-sonicated control samples. According to our results, it was clearly observed that glucose consumption increased after ultrasonic treatment representing the improved substrate uptake and progression of the cellular metabolism. Furthermore, the transmission electron microscopic images immediately after sonication clarified the pore formation on the cell surfaces. The results also indicated the enhancement of plasma membrane permeability of the sonicated cells. Fourier transform infrared spectroscopy and scanning electron microscopy coupled with energy dispersive x-ray spectroscopy analyses also disclosed respectively no structural differences before and after ultrasonic exposure in the produced biosurfactant and bacterial cell membrane. The biosurfactant was characterized to be a mixture of carbohydrate (28%), protein (23%) and lipid (specified by gas chromatography-mass spectrometry) known as glycolipoprotein. The sustainable critical micelle concentration and the stability of the synthesized biosurfactant can feature its potential applicability in various processes in the food and pharmaceutical industries.     

Inactivation of Escherichia coli and Streptococcus mutans by ultrasound at 500 kHz

This paper shows a systematic study of the 500 kHz frequency ultrasound efficiency on the microbial inactivation as a function of ultrasonic power delivered into the bacterial suspension. The inactivation of Escherichia coli IAM 12058, a Gram-negative bacterium and Streptococcus mutans JCM 5175, a Gram-positive bacterium is enhanced by increasing the ultrasonic power in the range of 1.7–12.4 W and the logarithm of survival ratio decreases linearly with irradiation time, except for E. coli sonicated with the highest power level. The rate constants were estimated in the linear region of the plots representing survival ratio logarithm vs. sonication time. A better understanding of the inactivation process at 500 kHz could be gained by suppressing the chemical effects with a radical scavenger. We find out that the rate constants increase with the ultrasonic power delivered into the solution and dramatically decrease by the addition of t-butanol as a radical scavenger to the bacterial suspension. For comparison, experiments were carried out at a low frequency level of 20 kHz. It was found out that for the same ultrasonic power delivered into the bacterial suspension, the inactivation was slightly enhanced at 500 kHz frequency. The examinations of bacterium performed with a TEM revealed lethal damages arising from the interaction of bacterial cells with the cavitational bubbles. A significant amount of empty cell envelopes as well as their cytoplasmatic content was detected. Thus, based on these new data, the mechanism of bacterial inactivation by ultrasounds at high frequency is discussed here.