Incorporation of Magnetite in Toughened PLA Nanocomposite: Tensile and Thermal Stability

In this study, liquid natural rubber (LNR) toughened polylactic acid (PLA) incorporated with magnetite (Fe3O4) nanocomposites were fabricated via melt-compounding in an internal mixer and followed by hot/cold pressing. The effects of ultrasonic treatment time (1-3 hours) and Fe3O4 (0.5-4.0 wt%) nanoparticles loading on tensile, morphology and thermal stability were investigated. Based on tensile testing results, the ultrasonication time of 1 hour was served as the most suitable treatment period to achieve the optimum distribution of Fe3O4 within PLA/LNR matrix. Among the investigated nanoparticles loading, 1 wt% Fe3O4 nanocomposite presented the highest tensile strength of 23.7 MPa, Young’s modulus of 1293.5 MPa and strain at break of 2.8%. SEM micrographs showed that the over-treated nanocomposites with 2-3 hours and over-high nanoparticles loading had resulted in the formation of clusters in the matrix. With increasing Fe3O4 loading, the decomposition of PLA/LNR nanocomposites was initiated earlier.

Preparation of Borneol Angelica Polysaccharide Liposomes and Study Evaluation of Its Anti-Cerebral Ischemia-Reperfusion Inflammatory Reaction

Objective To prepare borneol angelica polysaccharide liposomes (BAPLs) with distinct characteristics in Chinese and Western medicine, to explore their effects on anti-cerebral ischemia-reperfusion inflammatory reactions and to explain their mechanism. Methods Under the guidance of the basic theory of traditional Chinese medicine, a new dosage form of nanoliposomes was selected to prepare BAPL by the thin film dispersion ultrasonic method. The effects of angelica polysaccharide (AP), lecithin, cholesterol and ultrasonication time on encapsulation efficiency were investigated. Triphenyltetrazolium chloride (TTC) staining was used to detect the volume of cerebral infarction. Western blotting was used to detect the expression levels of TLR-4, NF-κBp65, ZO-1, ZO-2, IL-1β, IL-6, IL-8 and IL-10. Results As the mass ratio of lecithin to cholesterol (X1), the mass of angelica polysaccharide (X2) and the interaction between X1 and X2 (X1X2) were used as investigation factors, the fitting equation between encapsulation efficiency Y and X was Y=0.307-0.153X1+0.026 X2+0.006X12-0.000301 X22+0.002X1X2 (P＜0.05). The best ultrasonication time was 15 min, the highest encapsulation efficiency was 80.4%, the particle size was 179.1 nm, and the surface zeta potential was -17.2 mV. In BAPL group, the infarct volume of TTC staining was significantly decreased (P＜0.05), and the expression levels of NF-κBp65, TLR-4, IL-8, IL-6, IL-1β in brain tissue were significantly decreased (P＜0.05), while the expression levels of ZO-1, ZO-2, IL-10 were significantly increased (P＜0.05). Conclusion BAPL has high encapsulation efficiency, small particle size and stable properties and can alleviate cerebral ischemia-reperfusion injury. Its mechanism may be related to inhibiting inflammatory reactions, downregulating inflammatory reaction signaling pathways and protecting the blood–brain barrier (BBB).

Stability studies of hybrid TiO2 based nanofluids

This article studies the stability of hybrid TiO2 based nanofluid by varying the ultra-sonication time, weight fraction between carbon and TiO2 and type of surfactant. The objective of this research are synthesise volume fraction of 0.1% C - TiO2 hybrid nanofluid with 15ml of distilled water and study the effect of weight fraction between C and TiO2, type of surfactant and ultra-sonication time to the stability of hybrid nanofluid. Weight fraction between C – TiO2 will be varied at 0% - 100%, 10% - 90%, 50% - 50%, 90% - 10% and 100% - 0%. Different ultrasonication time will be used which are 1, 3 and 5 hours to determine the optimum ultrasonication time for the hybrid nanofluid. Sodium dodecyl sulphate (SDS) and Triton X-100 will be added into hybrid nanofluid to determine the effect of surfactant to the stability of hybrid nanofluid. The morphology and particle size characteristic of TiO2 and carbon powder is evaluated by using X-ray diffraction and FESEM. It is shown that TiO2 has particle size of around 30nm while carbon powder used is flat shaped. In this research, two steps method is used to synthesise the hybrid nanofluid. After mixing the two powder together, it will be mixed with distilled water by magnetic stirring for 3 hours. Then ultrasonication is included in synthesise of hybrid nanofluid to prevent agglomeration of particles. The pH values of each hybrid nanofluid is measured by using pH meter. Two stability evaluations are carried out which are centrifugation and zeta potential measurement. Centrifugation is carried out right after hybrid nanofluid is done ultra-sonicated for 30 minutes at 2000 RPM. Hybrid nanofluid that is ultra-sonicated for 3 hours resulted to achieve highest stability with highest value of zeta potential of -21.8 mV. 100% C - 0% TiO2 hybrid nanofluid has the highest zeta potential measurement of -37.6 mV. Finally, for type of surfactant, SDS able to enhance stability of hybrid nanofluid more than Triton X-100. The zeta potential of hybrid nanofluid after addition of SDS reached -47.0 mV which is higher than Triton X-100 which only achieve zeta potential measurement of -24.3 mV.

Low-frequency ultrasound bactericidal capacity study in intermittent ultrasonication process

The low-frequency ultrasound (f = 26.5 kHz) was found to have a bactericidal effect upon the main representatives of bacterial flora: Staphylococcus, Proteus, E-coli and Pseudomanas aeruginosa. However, ultrasound suppresses bacterial flora during a comparatively long ultrasonication time ranging from 18 to 27 min. It was found that the determinant factor ensuring the bactericidal effect of low-frequency ultrasound is cavitation. To reduce the required ultrasonication time, while maintaining the high bactericidal effect, Bauman Moscow State Technical University (BMSTU) has developed a new ultrasonic treatment method designed for infected wounds and patented in the RF [8]. When implementing this method, it is proposed to intensify the cavitational effect of ultrasound through complementary physical and chemical factors: low-concentration antiseptic agents, excessive external static pressure, and optimum temperature of ultrasonicated solution. The proposed intensification of ultrasonic effect was found to reduce the sterilization time of bacterial suspensions from 5 to 7.2 times, while keeping the maximum required ultrasonication time within 5 min. The article considers further potential reduction of cavitational exposure time for tissues on the basis of earlier found aftereffect of ultrasound. This aftereffect means that a pre-sonicated solution has higher bactericidal properties than non-sonicated solutions and preserves its bactericidal capacity for specific time [11]. The article demonstrates the efficacy of the continuous ultrasonication process replacement by the intermittent process, which follows the cycle: ultrasonication – pause – ultrasonication. Experiments proved that, with optimum temporal relationship between the periods of ultrasonic exposure and rest, the complete sterilization end-time of bacterial suspensions can be reduced still more by 20…30%. Thus, the proposed intermittent ultrasonication process is an effective instrument of reducing the cavitational exposure of an organism, while maintaining its high bactericidal effect no worse than that of the continuous ultrasonication process. The research findings were successfully tested in the Traumatology department of N.N. Burdenko Main Military Clinical Hospital during the trial of the proposed method for ultrasonic treatment of infected wounds.

Synthesis of Ternary Fe3O4/ZnO/Chitosan Magnetic Nanoparticles via an Ultrasound-Assisted Coprecipitation Process for Antibacterial Applications

In this study, Fe3O4/ZnO/chitosan magnetic nanoparticles were synthesized by an ultrasound-assisted coprecipitation method. The magnetic nanoparticles were characterized by XRD, FT-IR, FESEM, and VSM techniques. The effects of ultrasonication time and content of chitosan on crystal size and lattice parameters of the nanoparticles were also studied via XRD spectra. FESEM measurements revealed that the coating consists of Fe3O4/ZnO nanoparticles of 15-20 nm in diameter homogeneously dispersed on the surface of chitosan substance. The VSM measurements at room temperature showed that the Fe3O4/ZnO/chitosan nanoparticles had superparamagnetic properties. These results indicated that ultrasonication time and chitosan content had a significant effect on the characteristics of nanoparticles. The antibacterial activities of the Fe3O4/ZnO/chitosan were tested against both gram-positive Saccharomyces cerevisiae and Bacillus subtilis and gram-negative E. coli bacteria using a disk diffusion method.

Effects of ultrasonication time on stability, dynamic viscosity, and pumping power management of MWCNT-water nanofluid: an experimental study

It is known that ultrasonication has a certain effect on thermophysical properties and heat transfer of nanofluids. The present study is the continuation of the authors’ previous research on the effects of ultrasonication on the thermophysical properties of Multi-Walled Carbon Nanotubes (MWCNTs)-water nanofluid. Investigating the effects of ultrasonication time on samples’ stability, rheological properties, and pumping power of a water-based nanofluid containing MWCNTs nanoparticle is the main objective of the present study. The two-step method has been employed to prepared the samples. Moreover, a probe-type ultrasonic device has been used, and different ultrasonication times have been applied. The samples’ stability is investigated in different periods. The results revealed that prolonging the ultrasonication time to 60 min leads to improving the samples’ stability while prolonging ultrasonication time to higher than 60 min resulted in deteriorating the stability. As for dynamic viscosity, it is observed that increasing ultrasonication time to 60 min leads to decreasing the dynamic viscosity of the samples. As for pumping power, it is observed that the maximum increase in fanning friction factor ratio is less than 3%, which shows that adding MWCNTs to water does not impose a considerable penalty in the required energy for pumping power.

Effects of Ultrasonication Time on the Properties of Polyvinyl Alcohol/Sodium Carboxymethyl Cellulose/Nano-ZnO/Multilayer Graphene Nanoplatelet Composite Films

Ultrasonication-assisted solution casting was used to prepare polyvinyl alcohol (PVA)/sodium carboxymethyl cellulose (CMC)/nano-ZnO/multilayer graphene nanoplatelet (xGnP) composite films; the performances (mechanical properties, water vapor permeability (WVP), biodegradability and antibacterial activity) of these films were investigated as a function of the ZnO NPs:xGnP mass ratio and ultrasonication time. Intermolecular interactions among ZnO NPs, xGnP and the PVA/CMC matrix were shown to improve WVP, while X-ray diffraction and scanning electron microscopy analyses revealed that the internal reticular structure of ultrasound-treated PVA/CMC/ZnO NPs/xGnP composite films was in a fluffier state than that of the untreated composite films and the PVA/CMC film. The incorporation of ZnO NPs and xGnP into the composite film reduced its tensile strength and elongation at break, and increased antibacterial activity and biodegradability. In addition, we carried out the experiment of strawberry preservation and measured weight loss ratio, firmness, content of total soluble solids and titration acid. Finally, the composite film of 7:3 had the best preservation effect on strawberries. Thus, the obtained results paved the way to develop novel biodegradable composite films with antimicrobial activity for a wide range of applications.