连续臂丛神经阻滞镇痛对断指再植血流动力学影响的研究

目的研究连续臂丛神经阻滞镇痛对断指再植术后再植指血流动力学的影响，探讨其缓解血管痉挛、增加血流量的可行性。方法将60例急诊行断指再植术患者按随机数字表法分为术后连续臂丛神经阻滞镇痛组（CA组）和对照组（NA组），每组30例。观察两组患者再植指术后血管痉挛、血管栓塞和指体坏死发生例数并计算再植指成活率，记录两组术后即刻（T1）、术后24h（T2）再植指固有动脉血流动力学参数及动脉内径（AD）、远指端血氧饱和度（SpO2）和温度（Ts）变化。结果断指再植术后成活率CA组高于NA组，血管痉挛、血管栓塞和指体坏死发生率CA组均低于NA组，差异均有统计学意义（均P＜0.05）。在T2时CA组各项血流动力学参数、AD、SpO2、Ts均高于NA组，阻力指数（RI）低于NA组，差异均有统计学意义（均P＜0.05）。结论术后连续臂丛神经阻滞镇痛可以缓解再植指固有动脉痉挛，增加指体血流量，提高了断指再植的成功率。     

Determination of Pd,Rh, Pt,Au in road dust by electrothermal vaporization inductively coupled plasma mass spectrometry with slurry sampling

Inductively coupled plasma mass spectrometry coupled with ultrasonic slurry sampling electrothermal vaporization (USS-ETV-ICP-MS) has been applied to determine Pd, Rh, Pt and Au in 0.5% m/v slurries of several road dust samples. 2% m/v ammonium pyrrolidine dithiocarbamate (APDC) was used as the modifier to enhance the ion count. The influence of instrument operating conditions, slurry preparation and interferences on the ion count was reported. This method has been applied to the determination of Pd, Rh, Pt and Au in BCR 723 Road Dust and NIST SRM 2709 San Joaquin Soil reference materials and two road dust samples collected locally. The analysis results of the standard reference materials agreed with the certified values. Precision between sample replicates was better than 10% for all the determinations. The method detection limits estimated from standard addition curves were 0.9, 0.4, 0.6 and 0.4 ng g⁻¹ for Pd, Rh, Pt and Au, respectively, in original dust samples.     

Broadband dielectric characterization of piezoelectric poly(vinylidene fluoride)thin films between 278 K and 308 K

This work describes the dielectric properties of piezoelectric poly(vinylidene fluoride) (PVDF) thin films in the frequency and temperature ranges relevant for usual applications. We measured the isothermal dielectric relaxation spectra of commercial piezoelectric PVDF thin films between 10 Hz to 10 MHz, at several temperatures from 278 K to 308 K. Measurements were made for samples in mechanically free and clamped conditions, in the direction of the poling field (perpendicular to the film). We found that the imaginary part of the dielectric relaxation spectra of free and clamped PVDF samples is dominated by a peak, above 100 kHz, that can be characterized by a Havriliak-Negami function. The characteristic time follows an Arrhenius dependence on temperature. Moreover, the spectra of the free PVDF samples show two additional peaks at low frequencies which are associated with mechanical relaxation processes. Our results are important for the characterization of piezoelectric PVDF, particularly after the stretching and poling processes in thin films, and for the design and characterization of a broad range of ultrasonic transducers.     

基于ARM的嵌入式超声传播时间测量装置

应用超声波检测技术进行检测时,通常需对超声波在介质中的传播时间进行精准的测量,为精准测量超声波的传播时间,设计了一套基于ARM的嵌入式超声传播时间测量装置。该装置电路运行稳定,成本低廉,采用多次测量结果取算数平均值的方法以减小随机干扰,采用参比方法放置接收探头以消减电路中电子器件的延时。通过对实验结果进行分析,得出该装置可精准测量超声波在实验试块中的传播时间且满足设计要求,分辨率可达一纳秒。     

Ultrasound-assisted extraction of Cordyceps cicadae polyphenols: Optimization,LC-MS characterization,antioxidant and DNA damage protection activity evaluation

In this study, ultrasound-assisted extraction of polyphenols from C. cicadae was optimized by response surface methodology (RSM). The optimized conditions were determined as extraction time of 39 min, liquid-to-solid ratio of 1:29 g/mL, extraction temperature of 69 °C and ethanol concentration of 55% with a yield of 21.9 mg gallic acid equivalent/g dry weight. Four resins were used for polyphenol purification. D101 resin had the highest ratio of adsorption and was further applied in polyphenol purification test. A total of 19 different phenolic compounds were identified by LC-MS, including 12 phenolic acids and 7 organic acids. In addition, C. cicadae polyphenols displayed higher antioxidant activity in vitro and anti-aging activity of C. elegans in vivo. Lastly, C. cicadae polyphenols showed the potential to protect DNA from oxidative damage. Overall, our results suggest that polyphenols from C. cicadae may be considered as novel sources of anti-oxidation, anti-aging and recommended as reagents to protect DNA from oxidative damage in food and pharmaceutical industries.     

Built-in piezoelectric field improved photocatalytic performance of nanoflower-like Bi2WO6 using low-power white LEDs

Photocatalysis technology has been proved to be a potential strategy for removal of organic dyes, however high-power light sources are generally necessary to initiate photocatalytic reaction. In this work, we employed an excellent photocatalyst of Bi₂WO₆ with visible light harvest and meanwhile an intrinsic ferroelectricity, which realized the efficient degradation of organic dye via the synergetic photopiezocatalysis. Through coupling the illumination by a low-power (9 W) LED and the ultrasonic vibration (120 W) by an ultrasonic cleaner, the nanoflower-like Bi₂WO₆ composed of ultrathin nanosheets showed a much more enhanced photopiezocatalysis performance for purification of organic dye than the individual photocatalysis and piezocatalysis. Furthermore, the high mineralization efficiency and the good durability of the Bi₂WO₆ catalyst were demonstrated. The possible mechanism of photopiezocatalysis was finally proposed, where the ultrasound-induced piezoelectric field in Bi₂WO₆ drove photo-generated electrons and holes to diffuse along opposite directions, consequently promoting the separation efficiency of charge carriers. This work indicates that the synergetic photopiezocatalysis by coupling irradiation and ultrasonic vibration is a promising strategy to purify organic pollutants in wastewater.     

Fabrication of bacterial cellulose thin films self-assembled from sonochemically prepared nanofibrils and its characterization

Bacterial cellulose (BC) film formation could be a critical issue in nanotechnology applications such as biomedical or smart materials products. In this research, purified pretreated BC was subjected to high intensity ultrasound (HIUS) and was investigated for the development of BC films. The morphological, structural and thermal properties of the obtained films were studied by using FE-SEM, AFM, FT-IR, XRD, TGA and DSC characterizations. Results showed that the most favorable purification treatment was the 0.01 M NaOH at 70 °C for 2 h under continuous stirring. The most suitable ultrasound operating conditions were found to be, 1 cm distance of ultrasonic probe from the bottom of the beaker, submerged in cold water bath cooling around 12 ± 2 °C. The power (25 W/cm²), time (30 min), BC concentration (0.1% w/w), amplitude (20 μm) and frequency (20 kHz) were maintained constant.     

Ultrasonic washing of textiles

We present the results of experimental investigation of ultrasonic washing of textiles. The results demonstrate that cavitation bubbles oscillating in acoustic fields are capable of removing soils from textiles. Since the washing performance is mitigated in a large washing bath when using an ultrasonic transducer, we propose a novel washing scheme by combining the ultrasonic vibration with a conventional washing method utilizing kinetic energy of textiles. It is shown that the hybrid washing scheme achieves a markedly enhanced performance up to 15% in comparison with the conventional washing machine. This work can contribute to developing a novel laundry machine with reduced washing time and waste water.     

Physical and chemical effects of acoustic cavitation in selected ultrasonic cleaning applications

Acoustic cavitation in a liquid medium generates several physical and chemical effects. The oscillation and collapse of cavitation bubbles, driven at low ultrasonic frequencies (e.g., 20 kHz), can generate strong shear forces, microjets, microstreaming and shockwaves. Such strong physical forces have been used in cleaning and flux improvement of ultrafiltration processes. These physical effects have also been shown to deactivate pathogens. The efficiency of deactivation of pathogens is not only dependent on ultrasonic experimental parameters, but also on the properties of the pathogens themselves. Bacteria with thick shell wall are found to be resistant to ultrasonic deactivation process. Some evidence does suggest that the chemical effects (radicals) of acoustic cavitation are also effective in deactivating pathogens. Another aspect of cleaning, namely, purification of water contaminated with organic and inorganic pollutants, has also been discussed in detail. Strong oxidising agents produced within acoustic cavitation bubbles could be used to degrade organic pollutants and convert toxic inorganic pollutants to less harmful substances. The effect of ultrasonic frequency and surface activity of solutes on the sonochemical degradation efficiency has also been discussed in this overview.     

Ultrasonic-assisted synthesis of Pd–Pt/carbon nanotubes nanocomposites for enhanced electro-oxidation of ethanol and methanol in alkaline medium

Herein, a facile ultrasonic-assisted strategy was proposed to fabricate the Pd–Pt alloy/multi-walled carbon nanotubes (Pd–Pt/CNTs) nanocomposites. A good number of Pd–Pt alloy nanoparticles with an average of 3.4 ± 0.5 nm were supported on sidewalls of CNTs with uniform distribution. The composition of the Pd–Pt/CNTs nanocomposites could also be easily controlled, which provided a possible approach for the preparation of other architectures with anticipated properties. The Pd–Pt/CNTs nanocomposites were extensively studied by electron microscopy, induced coupled plasma atomic emission spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, and applied for the ethanol and methanol electro-oxidation reaction in alkaline medium. The electrochemical results indicated that the nanocomposites had better electrocatalytic activities and stabilities, showing promising applications for fuel cells.