ABSTRACT
In this work, we introduce trimethylbromosilane (C3H9SiBr), which can protect lithium metal anodes via an in situ formed SEI layer while catalyzing the decomposition of Li2O2. As a result, lithium-oxygen batteries with C3H9SiBr offer a long cycle life of 110 cycles with a significantly reduced charging/discharging overpotential.
ABSTRACT
To solve the difficulty of introducing traditional ultrasonic transducers to welding molten pool, high frequency current is used to modulate plasma arc and ultrasonic wave is excited successfully. The characteristics of the excited ultrasonic field are studied. The results show that the amplitude-frequency response of the ultrasonic emission is flat. The modulating current is the main factor influencing the ultrasonic power and the sound pressure depends on the variation of arc plasma stream force. Experimental study of the welding structure indicates grain refinement by the ultrasonic emission of the modulated arc and the test results showed there should be an energy region for the arc ultrasonic to get best welding joints.
ABSTRACT
Implanted nerve stimulation offers many advantages to improve the QOL (quality of life) of the patients suffering from nervous system diseases such as Parkinson's disease and epilepsy. Secondary battery begins to be used instead of primary secondary, service life of the implanted device is extended and the device becomes smaller and lighter. For charging the secondary battery fit in the body, a transcutaneous charger is designed. Two coupling coils designed specially are used to transmit and receive energy. With the mentioned coupling coils, the charger attains 15 mA charge current and the charge requirement is satisfied.
Subject(s)
Electric Stimulation Therapy , Electrodes, Implanted , Epilepsy/rehabilitation , Parkinson Disease/rehabilitation , Skin/pathology , Electric Power Supplies , Electronics, Medical , Equipment Design , Heart, Artificial , Human Body , Humans , Models, Statistical , Nerve Tissue/pathology , Peripheral Nervous System , RadiationABSTRACT
Under the background of algae removal and growth inhibition by ultrasonic irradiation, the effects of ultrasonic irradiation on removal of Microcystis, the concentration variation of microcystins (MC) produced by Microcystis in Microcystis suspension, and sonochemical degradation of microcystins in water, were studied in the paper. The results showed that ultrasonic irradiation could efficiently inhibit the growth of Microcystis, and ultrasonic irradiation shorter than 5 min would not introduce the increase of microcystins dissolved in Microcystis suspension simultaneity. Also, microcystins dissolved in Microcystis suspension would not increase as ultrasonic power increasing. Further research showed that microcystins were effectively degraded in ultrasonic fields. After 20 min ultrasonic irradiation at 150 kHz and 30 W, the removal rate of microcystins reached 70%.
Subject(s)
Microcystis/physiology , Peptides, Cyclic/biosynthesis , Bacterial Toxins/biosynthesis , Bacterial Toxins/pharmacokinetics , Biodegradation, Environmental , Eukaryota/physiology , Kinetics , Microcystins , Microcystis/radiation effects , Peptides, Cyclic/pharmacokinetics , Ultrasonics , Water MicrobiologyABSTRACT
Ultrasonic irradiations at high frequency of 1.7 MHz and low frequency of 20 kHz were tested to prevent cyanobacteria Spirulina platensis from bloom. The inhibition effectiveness at 1.7 MHz was much greater than that at 20 kHz. The cyanobacteria biomass was reduced by 63% after 5 min ultrasonic irradiation at 1.7 MHz, whereas three days were needed for the tested cyanobacteria to recover its original density. However, longer exposure time did not significantly enhance the inhibition. It was observed after ultrasonic irradiation that the gas vesicles in cells collapsed, which may result in cyanobacterial precipitation and photosynthetic inhibition. The concentration of chlorophyll a (Chla) was reduced and its biosynthesis was delayed in a 4-day continuous culture. The fluorescence spectra at 77K of phycobilisome (PBS) and absorption spectra of intact cells in vivo showed that light energy transfer in PBS was inhibited and phycocyanin (PC) was damaged much more acutely compared with Chla. These results indicated that 5 min ultrasonic irradiation at 1.7 MHz every third day might be an effective and economic operation mode for practical application.
Subject(s)
Bacterial Proteins , Ultrasonics , Water Purification/methods , Chlorophyll/analysis , Chlorophyll/biosynthesis , Chlorophyll A , Population Dynamics , Spirulina , Water MicrobiologyABSTRACT
Ultrasonic signals propagated through medium were directly applied to unicellular cyanobacterium cell surfaces to investigate the biological effects induced by ultrasound. The gas-vacuolate cyanobacterium Microcystis aeruginosa and the gas-vacuole negative cyanobacterium Synechococcus PCC 7942 responded differently to ultrasound. When M. aeruginosa was irradiated by 1.7 MHz ultrasound at 0.6 W cm(-2) every day, it showed a decrease of nearly 65% in biomass increment, and this group's generation time increased twice as much as the control. While Synechococcus culture irradiated every day still grew as fast as the control, and its final biomass was as much as the control. The value of the electric conductivity change (Deltasigma) sharply increased in Microcystis suspension during the exposure process, which revealed more ultrasonic cavitation yield in liquid related to the gas-vacuolate cyanobacteria. The relative malondialdehyde (MDA) content, a quantitative indicator of lipid peroxidation, increased by 65% in Microcystis cells and 9% in Synechoccus cells after ultrasonic irradiation. Moreover, the membrane permeability, quantified by measuring the relative amount of electrolyte leaking out of cells, increased to more than 60% in the Microcystis cells. The results indicated that Microcystis cells were susceptible to ultrasonic stress. According to Rayleigh-Plesset's bubble activation theory, 1.7 MHz ultrasound approached the eigenfrequency of gas-vacuolate cells. The present investigation suggested the importance of the cavitational effect relative to intracellular gas-vacuoles in the loss of cell viability. In summary, 1.7 MHz ultrasonic irradiation was effective in preventing water-bloom forming cyanobacteria from growing rapidly due to changes in the functioning and integrity of cellular and subcellular structures.
Subject(s)
Microcystis/radiation effects , Ultrasonics , Vacuoles/radiation effects , Biomass , Cell Count , Cell Membrane/radiation effects , Cell Survival/radiation effects , Electric Conductivity/adverse effects , Gases/radiation effects , Kinetics , Lipid Peroxidation/radiation effects , Malondialdehyde/analysis , Malondialdehyde/radiation effects , Microcystis/cytology , Microcystis/growth & development , Permeability/radiation effects , Synechococcus/cytology , Synechococcus/growth & development , Synechococcus/radiation effectsABSTRACT
The degradation process and mechanism of p-chlorophenol in water using high frequency ultrasound (1.7 mHz) was investigated in this paper. The p-chlorophenol was degraded successfully in the high frequency ultrasonic device with low consumption of energy. The degradation effect was improved by increasing the solution concentration. No products or intermediate products were detected in the reaction mixture by the analytic methods of MS and 1H-NMR after ultrasonic irradiation. The dominant degradation mechanism is high temperature pyrolysis in ultrasonic cavities rather than free radical oxidation, and the experimental results can be explained completely according to pyrolysis mechanism.
Subject(s)
Chlorophenols/radiation effects , Ultrasonics , Water Supply/analysis , Chlorophenols/chemistry , Kinetics , Mass Spectrometry , Oxidation-Reduction , Spectrophotometry, UltravioletABSTRACT
p-Chlorophenol (4-CP) is a recalcitrant organic pollutant that is biologically toxic in industrial wastewater. A high-frequency ultrasonic device operated at 1.7 MHz was designed and used successfully to degrade 4-CP. Iodine liberation in the KI aqueous solution confirmed that effective cavitation occurred under the high-frequency ultrasonic irradiation. No products or intermediate products were detected following the sonochemical degradation by 1H-nuclear magnetic resonance spectrum and mass spectrum after ultrasonic irradiation. It was concluded that the dominant degradation mechanism was high-temperature pyrolysis to inorganic products in ultrasonic cavities rather than free-radical oxidation.
