Ultrasonic Dispersion Research Articles

Fast and non-destructive ultrasonic test for face masks

As a consequence of the large demand of face masks due to the COVID19 pandemic, cheap, fast and non-destructive tests that can verify in-line the variability of the filtration capacities, prove the potential disinfection and/or evaluate the performance of new filtering materials are needed. Using two different approaches based on air-coupled ultrasounds (0.15–1.6 MHz) with equivalent results, this work shows that each face mask presents a distinctive ultrasonic signature that enables the classification and the evaluation of their performance. Moreover, it is shown that the ultrasonic propagation through the face masks and the main filter layers takes place through the pore space and that low frequency response of the attenuation and the velocity is highly dispersive and is dominated by the interaction between the air in the pores and the fibers in the filters. Hence, the parameters that describe ultrasonic velocity, attenuation and dispersion can be related with their filtration efficiency and breathability. These techniques are fully contactless, non-invasive and fast.

Multiple effects of nano-CaCO3 and modified polyvinyl alcohol fiber on flexure–tension-resistant performance of engineered cementitious composites

Nanomaterial modification and fiber reinforcement are both effective modifications for concrete toughening. In this study, the cement matrix was reinforced by a combination of nanomaterials and surface-modified polyvinyl alcohol (PVA). The modification of PVA involves the treatment of interface weakening, which is based on the enhancement of the slip effect. The workability and static mechanical properties of engineered cementitious composites (ECCs) were studied, and the micromorphology of the fiber and matrix after bending failure was observed through scanning electron microscopy. Different nanomaterial contents and concentrations of PVA were designed in the experiment, the purpose of which is to investigate the mechanism of the effect of multiple superposed on the toughening effect of ECCs. The research demonstrated that the direct addition of traditional PVA fiber and nanomaterials adversely affects the workability of ECCs, but it can be improved by fiber modification and ultrasonic dispersion of nanomaterials. An experimental study on the compressive properties showed that, with the increase in PVA fiber modification concentration, the compressive strength decreased, but the addition of nano-CaCO3 improved the strength of the matrix, thereby compensating for the strength loss. Four-point bending and tensile tests demonstrated that both PVA fiber modification and the addition of nano-CaCO3 affected the flexural properties of ECCs to some extent. PVA fibers modified with 1% and 2% nano-CaCO3 at vinyl acetate ethylene concentrations of 25% and 50% can improve the toughness of ECCs. Nano-CaCO3 can improve the toughness of ECCs by improving the compactness of the matrix structure and fiber interface, while PVA fiber can supplement the defects of the matrix structure by bridging and sliding and have a positive superposition effect on the toughness of the material after proper treatment.

Influence of graphene oxide content on the morphology and properties of carbon fiber/epoxy composites

AbstractIn this article, the influence of graphene oxide (GO) content on the morphology and properties of carbon fiber/epoxy (CF/EP) composites was investigated. To obtain CF/EP composites with uniform dispersion of GO, electromagnetic stirring and ultrasonic dispersion techniques were employed in the wet transfer process. Combined with a new molding process, CF/EP composites with different GO content were prepared. The test results showed that the bending strength of CF/EP composites could be effectively improved by adding GO, among which 0.5 wt% GO–CF/EP composite exhibited the best bending strength and modulus increased by 47.20% and 21.24%, up to 1158.9 MPa and 115.3 GPa. Likewise, the mode I interlaminar fracture toughness (GIC) of the composite at the beginning of crack and the maximum during the propagation increased by 28.13% and 21.57%, reached 327.5 and 656.6 J/m2, respectively. The distribution of GO in the composites and the fracture morphology of the composites were observed. Finally, according to the test results and microscopic morphology analysis, the enhancement and failure mechanism of GO in CF/EP composites were clarified. It was found that GO could improve the properties of CF/EP composites by enhancing the interface properties of CF/matrix, enhancing the strength of the matrix and forming a net‐like structure inside the matrix.

Application of Nanobubble-Based Ultrasound Combined with General Anesthesia for the Treatment of Colon Cancer Patients

The nanobubble has recently become a new method to diagnose tumors. In this paper, nanobubble was prepared as follows. First, distearoylphosphatidylcholine and polyethylene glycol-distearyl phosphatidyl ethanolamine were dissolved in 8:1 chloroform/ethanol, and then PBS buffer was added, followed by ultrasonic dispersion for 30 s, and a 65 °C water bath to completely evaporate the organic solvent. Next, 1.5 mL liposome suspension obtained was transferred in a 5 mL conical flask, with 2.5 mL perfluoropropane injected, followed by sonication for 1 min. Finally, the nanobubble was obtained. In this study, 30 patients with colon cancer who underwent radical resection of colon cancer divided into 2 groups with 15 patients in each group. Controls were treated with sham irradiation, while ultrasonic treatment group (DUS treatment group) was treated with ultrasonic irradiation (1 W/cm2 + 3 min) combined with intravenous injection of nanobubbles. The outcome indexes of the two groups were recorded before anesthesia induction (T1), after surgery (T2), 3 days after surgery (T3), and 7 days after surgery (T4). It was found that, the concentration of nanobubble was 1.5 × 108/mL, and the average particle size was 457.23 ±6.24 nm. Control group and DUS treatment group had lower heart rates (HR) at T2 versus that at T1 (P < 0.05). Also, the mean arterial pressure (MAP) of two groups at T2 (89.67±8.69 mmHg, 96.24 ±8.54 mmHg) was also lower versus that at T1 (P < 0.05). For the saturation of central venous oxygen (ScvO2), O2 transport index (DO2I), and O2 consumption index (VO2I) of two groups, the values at time T2–T4 were all superior to those at time T1 (P < 0.05). Ultrasonic technology based on nanobubble combined with general anesthesia can better maintain the stability of hemodynamics during surgery than conventional ultrasound.

Effect of xanthan gum and silica nanoparticles on improving foam properties of mixed solutions of short-chain fluorocarbon and hydrocarbon surfactants

The mixed dispersions of NPs, water-soluble polymer xanthan gum (XG), anionic hydrocarbon surfactant (sodium dodecyl sulfate [SDS]), and nonionic fluorocarbon surfactant (FS-50) were prepared by using an ultrasonic dispersion instrument to investigate the enhancement mechanism of NPs on the foam properties of surfactant. The molecular interactions, foamability, and foam stability of the mixed dispersions were comprehensively studied. Results suggested that the addition of XG resulted in an evident change of micelles from wormlike and spherical to threadlike in the solutions of FS-50/SDS. The foaming ability and foam stability of mixed dispersions were significantly affected by NPs and XG concentration. XG could better enhance foam stability of FS-50/SDS solutions compared with NPs, but lead to rapid decrease in foaming ability. NPs could enhance foaming ability and foam stability of FS-50/SDS solutions. Performance-enhanced foam, including foaming ability and foam stability, could be obtained by controlling the addition of XG and NP concentration.

The Effect of Temperature on the Electrical Characteristics of Nanofluids Based on Palm Oil

This study sought to apply nanotechnology to develop the electrical characteristics of palm oil. Experiments were conducted using three types of nanoparticles: zinc oxide (ZnO), titanium dioxide (TiO2), and barium titanate (BaTiO3). The nanofluid samples were prepared by mixing the nanoparticles with palm oil using various processes. In the first scenario, a combination of palm oil with nanoparticles at 0.01 vol% was created, while the next sample had 0.03 vol% of nanoparticles. The samples were then fully dispersed using a magnetic stirrer, followed by ultrasonic dispersal in order to ensure homogeneity of the nanofluid. The electrodes were set 2.5 mm apart and the test was performed six times on each test sample in compliance with the IEC 60156 standard. The voltage breakdown characteristics were recorded for each of the liquids at temperatures varying from 35 °C to 90 °C. The results showed that for the palm oil samples containing nanoparticles, the voltage breakdown was greater than for the samples containing unmodified palm oil.

Ultrasonically dispersed ultrathin g-C3N4 nanosheet/BaBi2Nb2O9 heterojunction photocatalysts for efficient photocatalytic degradation of organic pollutant

Here, we present new graphite-like C3N4 (g-C3N4)/BaBi2Nb2O9 composites with remarkable photocatalytic activities under solar light irradiation that were prepared by a facile ultrasonic dispersion method. A heterojunction was formed with Aurivillius type BaBi2Nb2O9 particles and ultrathin g-C3N4 nanosheets, and this composite material was characterized by using several techniques. The ultrathin g-C3N4 nanosheets promoted extensive contact in the heterojunction, as observed by morphological analyses. Moreover, the as-synthesized ultrathin g-C3N4 nanosheets are highly porous with a specific surface area of 141 m2/g. The BaBi2Nb2O9 particles strongly absorb ultraviolet (UV) light whereas, by comparison, g-C3N4 absorbs visible light more effectively, as established by diffuse reflectance spectroscopy DRS analysis. These properties substantially improved the capacity of the as-fabricated g-C3N4/BaBi2Nb2O9 heterojunction to photocatalytically degrade the organic dye Rhodamine B (RhB) under simulated solar light and 40 W UV–visible light irradiation, versus either of the separate components of the heterojunction. Specifically, an optimal composite with approximately 30 wt% BaBi2Nb2O9 content exhibits an apparent reaction rate 0.02056 min−1 for RhB photodegradation under simulated solar light, which was nearly 1.5- and 4.3-fold higher than that of the pristine g-C3N4 and BaBi2Nb2O9 photocatalysts, respectively. In addition, the same composite had an apparent reaction rate of 0.0155 min−1 for RhB photodegradation under 40 W UV-Vis light irradiation, which was approximately 1.4- and 2.8-fold higher than the pristine components. These functionalities are also supported by photoluminescence spectroscopy analyses and photocurrent responses, which indicate a photosynergistic effect for the g-C3N4/BaBi2Nb2O9 heterojunction that enhances photoinduced interfacial charge transfer.

Stability of Graphene Oxide-Al2O3 Hybrid Nanofluids

In recent years, more and more researches and reports on nanofluids have been made, and hybrid nanofluids as new fluids have gradually entered the field of vision. Hybrid nanofluids have many excellent properties at the same time. Because the stability of hybrid nanofluids has an important influence on the thermal properties and flow heat transfer properties of the solution, the stability of nanoparticles suspended in the base liquid has become an important direction of research. The stability of graphene oxide-Al2O3 hybrid nanofluids was studied with ultrasonic time, dispersant and ultrasonic power as variables. The experimental results show that when the ratio of graphene oxide: Nano-Al2O3: dispersant is 1:1:1, ultrasonic time is 2 h and ultrasonic power is 300 w, the stability of graphene oxide- Al2O3 hybrid nanofluid solution is the best.

Fabrication and evaluation of Lambda-Cyhalothrin nanosuspoemulsion with pH- and temperature-responsive based on polyethylene wax as carrier

Using polyethylene wax (PW) as the coating matrix, the lambda-cyhalothrin-PW nanosuspoemulsion (LC-PW) with a particle size of 80-150nm was prepared through high-speed stirring, hot melt emulsification and ultrasonic dispersion. The formulation and composition of the LC-PW were optimized, the morphology of the LC-PW was analyzed by dynamic light scattering (DLS) and TEM, and the structure of the LC-PW was characterized by UV and IR. The anti-photolysis test showed that LC-PW had a good anti-photolysis performance. Furthermore, LC-PW could sustainably release Lambda-cyhalothrin, which was pH- and temperature dependent. The insecticidal activity analysis in the greenhouse indicated that the toxic strength between LC-PW and LC-SC (lambda-cyhalothrin-suspension concentrate) to Mythimna separata was similar within the same concentration ranges tested, but the insecticidal duration of LC-PW was significantly longer than LC-SC. Thus, the new type of LC-PW with the properties of anti-photolysis and controlled release is suitable for application in the field as a better insecticide.

Effect of Graphene Content on the Micromorphology, Microhardness and Micro Frictional Resistance of Co-Ni-Graphene Composite Coating

In order to obtain the alloy composite material with high hardness, good anti-friction property and low friction coefficient, the electrodeposition technology was used to prepare nanocrystalline Co-Ni-graphene composite coating on the surface of low carbon steel by means of ultrasonic dispersion combined with mechanical agitation. The influence of graphene content in electrolyte on composite coating was studied. The surface microstructure, composition, phase structure, micro-hardness and micro-wear properties of composite coating were measured by scanning electron microscopy, energy spectrometer, X-ray diffractometer, micro-hardness tester and UNMT-1 comprehensive mechanical testing system for micro-nanometer materials. The results show that with the increase of the content of graphene in the electrolyte the graphene particles were embedded in the alloy coating, which changes the crystal structure of the alloy coating and improves the microhardness and micro friction resistance of the coating. When the content of graphene in the electrolyte was 0.9g/L the microstructure of the composite coating was fine and uniform, the highest microhardness value was 678 HV, the minimum average friction coefficient was 0.15, and the composite coating had good wear resistance.

Spark Plasma Sintering of Nano Silicon Carbide Reinforced Alumina Ceramic Composites

Although Al2O3 has been commercially preferred material, it cannot be used in applications subject to variable and sudden loads due to its low fracture toughness. In this study, as the primary purpose, to improve the fracture toughness of the Al2O3/nano-SiC particles was used as reinforcement phase. Ultrasonic dispersion was used to ensure good dispersion of the nano reinforcement phase in the matrix. Production was carried out by spark plasma sintering method at temperatures of 1325 °C for 5 min under 40 MPa pressure and vacuum atmosphere. After production process, sintering behavior, density, microstructure, phase structure, hardness and fracture toughness of the Al2O3/nano-SiC composites were analyzed. The highest hardness and fracture toughness of 22.83 GPa and 6.09 MPa·m1/2 was achieved, respectively.

Exploitation of nanocrystal suspension as an effective oral formulation for oxfendazole.

An oxfendazole (OFZ) nanocrystal suspension was prepared by acid-base neutralization and crystallization combined with ultrasonic dispersion to overcome the challenge of its poor oral bioavailability. The nanosuspensions were screened and optimized by single-factor experiments and an orthogonal design using size and appearance as indices. The morphology (differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD)) properties and pharmacokinetics of the best formulation were further developed. The results showed that the best cosolvent and stabilizer were malic acid and hydrogenated castor oil polyoxyethylene ether (HEL-40), respectively. Scanning electron microscopy demonstrated that the oxfendazole nanocrystals are irregular sheets with relative uniformity. The prepared nanocrystals have an average particle diameter of 431 ± 18nm, a polydispersity index (PDI) of 0.376 ± 0.128, a zeta potential of 2.30 ± 0.44mV, and a sedimentation coefficient of 0.993. The equilibrium solubility of nanocrystals in different solvents was significantly improved by 2.02-109.99-fold compared to OFZ crude. In 0.5% SDS-PBS (pH 2) and 0.5% SDS-PBS (pH 8) solution, oxfendazole nanocrystals were completely released within 5min, while the OFZ crude only released 60.26% and 28.31%, respectively. The pharmacokinetics showed that the Cmax, Tmax, and AUC0-∞ of OFZ nanosuspension and OFZ granules in rats after oral dosage at 50mg/kg were 4.23 and 13.63μg/mL, 2.04 and 1.67h, and 111.36 and 295.80μg*h/mL, respectively. The relative bioavailability of the oxfendazole nanosuspension was 265.61% compared to the OFZ granules. These results showed that the nanosuspension might be a promising oral formulation for the hardly soluble OFZ.

Experimental investigations on nano-titania incorporated polyvinyl alcohol- polyvinyl pyrrolidone composite films

ABSTRACT Composite films were prepared by using polyvinyl alcohol – polyvinyl acetate copolymer (PVA/Ac) blended with polyvinyl pyrrolidone (PVP) as the host polymeric material and titania (TiO2) nanoparticles (NPs) as the filler, by using ultrasonic dispersion of the filler in PVA/Ac-PVP blend solution, followed by solution casting method. Free standing films of this composite were characterized by using powder x-ray diffraction (XRD) technique, differential scanning calorimetry (DSC), thermo-gravimetric (TG) analysis, transference number determination, as well as DC and dielectric measurements. XRD patterns confirmed the incorporation of titania NPs within the polymer blend (PVA/Ac-PVP). DSC and TG techniques shows that glass transition temperature of the composite decreased and thermal stability increased on incorporating TiO2 NPs, respectively. Wagner’s polarization technique, which was employed to determine the transference number revealed that ions were the majority mobile charge carriers. The activation energy (Ea ) has been determined from DC electrical measurements using the Arrhenius equation; Ea was found to decrease with an increase in the filler level (FL) of titania NPs in the polymeric blend. Dielectric studies revealed maximum ionic conductivities of 7.4 × 10−5 Sm−1 and 8.63 × 10−3 S m−1 for the composite film with FL 4.90 Wt%, at temperatures 303 K and 363 K, respectively.

Обезвоживание пищевых продуктов под действием ультразвуковых колебаний с удалением влаги без фазового перехода

Introduction. Dehydration of heat-sensitive and easily oxidized food products require particular temperatures. Exposure to ultrasonic vibrations is an alternative dehydration method that presupposes moderate thermal treatment. The research objective was to identify the optimal range of sound pressure and to design a small-volume dryer.
 Study objects and methods. The study featured two novel ultrasonic potato dryers at t = 60 ± 1°C and a drying agent flow rate of 0.50 ± 0.03 m/s.
 Results and discussion. The analysis of the drying curves revealed a period of constant flow rate at a low ultrasonic exposure and its absence at a high level of exposure of ≥ 160 dB, which indicated the start of the ultrasonic dispersion process of liquid from the potato surface. The dispersion occurred due to cavitation spraying of liquid without phase transition, which significantly reduced energy consumption. As the sound pressure increased in the range from 150 to 165 dB, the drying speed increased up to 26% by 5 dB. The optimal range of the sound pressure was 160–165 dB, which optimally combined energy consumption and drying time. The research resulted in two 6 kg horizontal and vertical drum dryers that provided even ultrasonic exposure during drying.
 Conclusion. The convective ultrasonic potato drum dryers reduced the drying time by 44–47%

Ni–Ru-containing mixed oxide-based composites as precursors for ethanol steam reforming catalysts: Effect of the synthesis methods on the structural and catalytic properties

Abstract Ethanol steam reforming catalyst’s precursors, i.e., nanocomposites of complex oxides with the general formula [Pr0.15Sm0.15Ce0.35Zr0.35O2 + LaMn0.45Ni0.45Ru0.1O3] (1:1 by mass), were synthesized by three different methods. It was shown that two synthesis methods – ultrasonic dispersion and sequential polymeric method, lead to the formation of the nanocomposite perovskite–fluorite system with the specific surface area up to 50 m2/g. Reduction of samples at 400–500°C lead to the formation of Ni–Ru alloy nanoparticles strongly bound with the surface of oxide nanocomposite. Catalytic tests in ethanol steam reforming reaction at 500–600°C showed the highest specific activity of the sample prepared by the sequential polymeric method due to the location of Ni- and Ru-containing perovskite mainly on the surface of the composite providing a high concentration of active metal centers. At higher temperatures for all samples, ethanol conversion approached 100% with hydrogen yield varying in the range of 65–75%. A study of spent catalysts confirmed the absence of carbon deposits after long-term catalytic tests at 650°C.

Effect of ultra-sonic dispersion time on hydration process and microstructure development of ultra-high performance glass powder concrete

This article is the continuous research on the successful attempt to utilize glass powder in ultra-high performance concrete. The previous study showed, that glass powder has a positive effect on the Portland cement hydration process, however, one problem was unable to overcome: about half the amount of unreacted clinker mineral remained in the composition, even when thermal treatment was applied. This research proposes a successful adaptation of the ultra-sonic dispersion method. The proposed method allowed to increase even further hydration process of the binder as well to develop a more favourable microstructure. Experiment research was investigated by XRD analysis, Chapelle, semi-adiabatic calorimetry, 29Si MAS NMR, mercury intrusion porosimetry, and compressive strength test methods. Results revealed, that high-frequency ultra-sonic dispersion can significantly increase the hydration degree of binder and the compressive strength up to 16%.

Significantly Enhanced Thermal Decomposition of Mechanically Activated Ammonium Perchlorate Coupling with Nano Copper Chromite.

In this article, nano-CuCr2O4 (copper chromite)/ultrafine ammonium perchlorate (AP) composites were prepared by a ultrasonic dispersion method and a mechanical grinding method. A series of nano-CuCr2O4/ultrafine AP composites with different dispersions were prepared by controlling the compounding time to study the best catalytic effect of nano-CuCr2O4 on the ultrafine AP. The microstructures, surface elements, and morphologies of samples were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersion X-ray spectroscopy. The catalytic effect of nano-CuCr2O4 on the thermal decomposition of AP was investigated by differential scanning calorimetric techniques and thermogravimetric analysis. The results indicated that the mechanical ball milling method could make nano-CuCr2O4 more evenly dispersed on the ultrafine AP, and with the increase in the milling time, the uniformity of nano-CuCr2O4 on the ultrafine AP was better. When the milling time was 6–12 h, nano-CuCr2O4 was most evenly dispersed on the ultrafine AP. At this time, the decomposition temperature and Gibbs free energy of the nano-CuCr2O4/ultrafine AP composite were the lowest, which decreased by 78.1 °C and 25.16 kJ/mol compared with those of ultrafine AP, respectively. Moreover, the mechanical sensitivity of nano-CuCr2O4/ultrafine AP composites was lower than that of ultrafine AP. It showed that ball milling for 6–12 h could make nano-CuCr2O4 evenly dispersed on the ultrafine AP, and nano-CuCr2O4 could play the best catalytic effect on the ultrafine AP.

Influence of ultrasonic treatment on kinetic of asphaltene aggregation in toluene/heptane mixture

This article illustrates the results of a study of ultrasonic dispersion’s influence on kinetic of asphaltene aggregation in a toluene/heptane mixture. The study was carried out by the method of dynamic light scattering. This optical method allows to measure the size of nano- and submicron particles in liquid medium. This method allows to measure the dependence of the average size of asphaltene aggregates during primary and secondary asphaltene aggregation. The primary aggregation was studied in a solution of asphaltenes in toluene and was initiated by the addition of heptane. Secondary aggregation of asphaltenes was initiated by ultrasonic dispersion of a mixture of toluene/heptane/asphaltene, in which primary aggregation finished and which contained asphaltene floccules. The effect of stabilization of asphaltene aggregates was experimentally detected after multiple ultrasonic dispersions.

Dispersion State and Damage of Carbon Nanotubes and Carbon Nanofibers by Ultrasonic Dispersion: A Review.

Dispersion of carbon nanotubes and carbon nanofibers is a crucial processing step in the production of polymer-based nanocomposites and poses a great challenge due to the tendency of these nanofillers to agglomerate. Besides the well-established three-roll mill, the ultrasonic dispersion process is one of the most often used methods. It is fast, easy to implement, and obtains considerably good results. Nevertheless, damage to the nanofibers due to cavitation may lead to shortening and changes in the surface of the nanofillers. The proper application of the sonicator to limit damage and at the same time enable high dispersion quality needs dedicated knowledge of the damage mechanisms and characterization methods for monitoring nano-particles during and after sonication. This study gives an overview of these methods and indicates parameters to be considered in this respect. Sonication energy rather than sonication time is a key factor to control shortening. It seems likely that lower powers that are induced by a broader tip or plate sonicators at a longer running time would allow for proper dispersions, while minimizing damage.

The Effect of Addition Graphite Filler on Mechanical Properties of Epoxy Material

The current study focuses on the effect of addition graphite filler on mechanical properties of epoxy material. The tensile and bending samples preparation of pure epoxy samples and epoxy with graphite powder with different weight ratio (0.15%, 1%, 2%wt) using ultrasonic dispersion device. The results showed the tensile stress and bending resistance were improved at (0.15%wt) and decreased at (1%, 2% wt), the decrease in tensile strength and bending resistance may be use of less time or low ultrasonic energy. The impact test improved at ratio (1%wt) and decreased at ratio (2% wt). There are decrease in hardness values with increase in graphite wieght fraction due to the lubricant effect of graphite flakes. In addiion of, the distribution of graphite can also affect this result where the penetrant was just on the surface.