低强度超声波强化污水生物处理技术

国内外研究发现低强度的超声辐照可以有效促进微生物的活性,因此可将其用于强化污水的生物处理,通过增强反应器内微生物的活性来提高污水的处理效率。介绍了低强度超声波强化生物活性的机理以及主要影响因素。概述了利用该技术强化污水生物处理的研究现状,并对未来的应用前景进行了展望。

强超声场下表面修饰对WS_2分散稳定性的影响

在自行设计的超声波分散实验装置上,采用强超声场下表面修饰法处理自制纳米WS2颗粒,以提高其在润滑油中的分散稳定性,分别考察了表面修饰剂用量及超声波处理时间对纳米WS2颗粒分散稳定性的影响,通过颗粒平均粒度及稳定时间评价分散效果,并通过NaOH滴定法和红外光谱分析法分析和探讨了纳米WS2颗粒在润滑油中的分散机理。结果表明,强超声波作用下,纳米WS2颗粒团聚体明显变小,分散稳定性显著提高,再经表面修饰,颗粒表面羟基与表面修饰剂发生作用,大量长链亲油基团取代表面羟基而吸附在颗粒表面,形成位阻层,有效地防止了颗粒的碰撞团聚和重力沉降,使纳米WS2颗粒在润滑油中形成了一个均匀且稳定的分散体系,而且在强超声场下进行表面修饰时,表面修饰剂的最佳用量为0.4—0.5倍纳米WS2颗粒的质量,最佳超声波处理时间为5 h。

Superacid Catalyst SO4^2-/ZrO2-La2O3 Prepared by Ultrasonic Co-precipitation and Low Temperature Aging

Sulfated zirconia-lanthana （SO4^2-/ZrO2-La2O3） precursors were prepared by ultrasonic coprecipitation method and followed by aging at different temperature. The precursors were treated by 0.5 mol/L H2SO4. Samples of SO4^2-/ZrO2-La2O3 nano-crystalline catalysts were obtained by baking the treated precursors at different temperatures. The acidic properties of SO4^2-/ZrO2-La2O3 were tested by the Hammett indicator method. The phase composition, specific area, particle structure, and surface state were characterized by X-ray diffraction, BET, transmission electron microscopy, infrared spectrum, and X-ray photoelectron spec- troscopy. The catalytic activities were estimated by esterification of acetic acid with glycerin. It was shown that the catalyst prepared by ultrasonic stirring and low temperature （-15 ℃） exhibited highly active sites and high catalytic property.

Contrast-enhanced and targeted ultrasound

Ultrasonic imaging is becoming the most popular medical imaging modality,owing to the low price per examination and its safety.However,blood is a poor scatterer of ultrasound waves at clinical diagnostic transmit frequencies.For perfusion imaging,markers have been designed to enhance the contrast in B-mode imaging.These so-called ultrasound contrast agents consist of microscopically small gas bubbles encapsulated in biodegradable shells.In this review,the physical principles of ultrasound contrast agent microbubble behavior and their adjustment for drug delivery including sonoporation are described.Furthermore,an outline of clinical imaging applications of contrast-enhanced ultrasound is given.It is a challenging task to quantify and predict which bubble phenomenon occurs under which acoustic condition,and how these phenomena may be utilized in ultrasonic imaging.Aided by high-speed photography,our improved understanding of encapsulated microbubble behavior will lead to more sophisticated detection and delivery techniques.More sophisticated methods use quantitative approaches to measure the amount and the time course of bolus or reperfusion curves,and have shown great promise in revealing effective tumor responses to anti-angiogenic drugs in humans before tumor shrinkage occurs.These are beginning to be accepted into clinical practice.In the long term,targeted microbubbles for molecular imaging and eventually for directed anti-tumor therapy are expected to be tested.

Fabrication of carbon nanotubes reinforced AZ91D composites by ultrasonic processing

Magnesium matrix nanocomposite reinforced with carbon nanotubes(CNTs/AZ91D) was fabricated by mechanical stirring and high intensity ultrasonic dispersion processing.The microstructures and mechanical properties of the nanocomposite were investigated.The results show that CNTs are well dispersed in the matrix and combined with the matrix very well.As compared with AZ91D magnesium alloy matrix,the tensile strength,yield strength and elongation of the 1.5%CNTs/AZ91D nanocomposite are improved by 22%,21%and 42%respectively in permanent mold casting.The strength and ductility of the nanocomposite are improved simultaneously.The tensile fracture analysis shows that the damage mechanism of nanocomposite is still brittle fracture.But the CNTs can prevent the local crack propagation to some extent.

Process and anodic reaction mechanism of cadmium electrically enhanced cementation on zinc plate under an ultrasonic field in ammoniacal system

Cadmium was replaced by zinc in ammoniacal system using an electrically enhanced method under ultrasonic waves.Five main influencing factors were investigated by a single-factor experiment to determine the optimum parameters.Cyclic voltammetry and linear sweep voltammetry were applied to investigating the reaction mechanism of electrically enhanced cementation of cadmium on a zinc plate.The optimum parameters were a temperature of 35℃,a cathode-to-anode area ratio of 1:2,an anode current density of 15 A/m2,an ultrasonic frequency of 40 kHz a reaction time of 6 h and an ultrasonic power of 100 W.The extraction rate was 99.21%,and the production of byproduct“floating sponge cadmium”was inhibited.The analysis of the cyclic voltammetry and linear sweep voltammetry diagrams showed that ultrasonic waves can promote and accelerate the replacement reaction,decrease the voltage requirement of the electrically enhanced replacement reaction,and change the reaction steps.In addition,increasing the temperature and ultrasonic power can promote and accelerate electrically enhanced replacement reactions and decrease the electric potential requirement.

The Efficacy of High-Intensity Focused Ultrasound (HIFU) in Advanced Pancreatic Cancer

OBJECTIVE To observe the efficacy of high-intensity focused ultrasound (HIFU) in the treatment of late-stage pancreatic cancer. METHODS Sixteen patients with advanced pancreatic cancer received HIFU therapy.Evaluation of efficacy was made on the basis of changes in clinical symptoms and variations in the tumor echo and size. RESULTS Clinical symptoms such as pain were significantly alleviated,echo of the tumor was enhanced with B-US and the quality of life such as eating,sleeping and mental status was markedly improved;no serious complications were observed. CONCLUSION The use of HIFU in the treatment of advanced pancreatic cancer is feasible and safe.It is effective in killing the carcinoma cells and alleviating pain.This technique may offer non-invasive therapy for the treatment of patients with late-stage pancreatic cancer.

Complications of high intensity focused ultrasound in patients with recurrent and metastatic abdominal tumors

AIM： To analyze the local and systemic complications of high intensity focused ultrasound （HIFU） for patients with recurrent and metastatic abdominal tumors. METHODS： From Aug 2001 to Aug 2004, 17 patients with recurrent and metastatic abdominal tumors were enrolled in this study. Real-time sonography was taken, and vital signs, liver and kidney function, skin burns, local reactions, and systemic effects were observed and recored before, during, and after HIFU. CT and MR/were also taken before and after HIFU. RESULTS： All 17 patients had skin burns and pain in the treatment region; the next common complication was neurapraxia of the stomach and intestines to variable degrees. The other local and systemic complications were relatively rare. Severe complications were present in two patients; one developed a superior mesenteric artery infarction resulting in necrosis of the entire small intestines, and the other one suffered from a perforation in terminal ileum due to HIFU treatment. CONCLUSION： Although HIFU is a one of noninvasive treatments for the recurrent and metastatic abdominal tumors, there are still some common and severe complications which need serious consideration.

Effects of low-intensity pulsed ultrasound stimulation on porous hydroxyapatite blocks for posterolateral fusion of lumbar spine in rabbits

he effects of porous hydroxyapatite blocks（PHABs） and an adjunct low-intensity pulsed ultrasound stimulation（LIPUS） on the fusion rate in a rabbit spinal posterolateral fusion（PLF） model were evaluated.Twenty rabbits underwent PLF with autograft and PHABs were randomly assigned to two groups：treated group with 20 min LIPUS daily and untreated control group for 4 weeks until euthanasia.The fused motion segments were subjected to manual palpation,gross observation,and radiographic investigation before histomorphologic and scanning electron microscopic analyses.Statistical differences between the LIPUS group and the control group are found in the fusion rate,bone density gray scale,trabecular bone formation,osteoblast-like cells,chondrocytes and positive expression of BMP-2 and TGF-β1 in the junction zone（significance level p〈0.05）.The results suggest that LIPUS can increase fusion rates and accelerate bone in-growth into PHAB.Hence,PHAB and LIPUS may be used together to increase fusion rates in a rabbit spinal fusion model with a promising extension to human application.

ULTRASOUND INDUCED AND LASER ENHANCED COLD FUSION CHEMISTRY

The standard model of sonoluminescence suggests that the Coulomb barrier to deuterium fusion may be overcome by high bubble gas temperatures caused by compression heating if the bubble diameter remains spherical during bubble collapse.However, in the more likely collapse geometry of a pancake shape, the temperature rise in the bubbles is negligible. But the collapsing pancake bubble is found to significantly increase the frequency of the infrared energy available in the vibrational state of the water molecules at ambient temperature. For a collapse to liquid density, ultraviolet radiation at about 10eV is found. Although the ultraviolet radiation is of a low intensity, higher intensities may be possible if the bubble collapse is enhanced by visible and infrared lasers. Neither hot nor cold fusion is predicted in bubble collapse,but the ultraviolet energy at about 10eV developed in the bubble is sufficient to provide the basis for a new field of chemistry called ultrasound induced and laser enhanced cold fusion chemistry.

建筑工程结构、材料测试方法的探讨

介绍混凝土结构非破损回弹—超声波综合法测强试验在怀化地区的应用及混凝土细骨料细砂的使用方法、小型异型钢材试验方法 ,并对普通粘土砖快速试验方法进行讨论。

Enhancement of fine particle filtration with efficient humidification

Filtration is one of the most effective methods to remove suspended fine particles from air. In filtration processes,pressure drop of compact dust cake causes problems in efficiency and economy, which has received increasing attention and still remains challenging. In this study, we developed a novel technique to intensify the filtration of fine particles with efficient humidification. Two strategies for humidification, including ultrasonic atomization and steam humidification(controlling of ambient humidity), were employed and proved to be both effective. The regeneration frequency of the filter could be reduced by 55% with ultrasonic atomization, while steam humidification could lead to a 78% reduction in regeneration frequency. The effect of operating conditions on pressure drop and the mass loading during filtration were investigated. The dust cake showed a loose and porous structure with an optimized droplet-to-particle ratio. With the ratio of 1.53 and 0.0282, the maximum mass loading was 552 g·m-2upon the ultrasonic atomization and 720 g·m-2upon the steam humidification. The results show that humidification could slow down the increase of pressure drop during filtration and improve the efficiency of process.

A case of eosinophilic cholangitis:Imaging findings ofcontrast-enhanced ultrasonography, cholangioscopy, andintraductal ultrasonography

A 38-year-old woman was referred to our institution due to epigastralgia. She presented with obstructive jaundice and eosinophilia. Endoscopic retrograde cholangiopancreatography showed diffuse narrowing from the distal common bile duct to the bifurcation of the hepatic ducts. An endoscopic plastic biliary stent was inserted; the specimen obtained from the common bile duct wall revealed dense infiltration by eosinophils. Treatment was started with prednisolone 60 mg daily. The patient's biliary stenosis and eosinophilia gradually improved. Eosinophilic infiltration in the lungs or stomach is relatively common, but it is rare in the common bile duct. Most of the reported cases of eosinophilic cholangitis presented with eosinophilia; our patient's eosinophil count was over 1000/mm3. Since our patient had allergies to pollen and house dust, a relationship between the allergies and the eosinophilic cholangitis was suspected, but no cause was identified.

Ultrasonic Study on Jahn-Teller Distortions in La1/3Sr2/3CoO3

The longitudinal ultrasonic velocity （V1）, attenuation （α1）, magnetization and resistivity of single phase polycrystalline La1/3Sr2/3CoO3 were measured as a function of temperature from 20 K to 300 K. The resistivity shows metallic behavior in the whole temperature range and a kink at 235 K was observed, which coincides with the ferromagnetic transition temperature （Tc）. As the temperature cools down from Tc, the V1 softens conspicuously at beginning and reaches a minimum at 120 K. After that the V1 dramatically stiffens below 120 K accompanied by a wide attenuation peak. The analysis of the results suggests that these ultrasonic anomalies ;nay correspond to local lattice distortions via the Jahn-Teller effect of intermediate spin Co^3＋.

Ultrasound assisted electrocatalytic oxidation of 3-chlorophenol in aqueous solution

Ultrasound assisted electrocatalytic process was used for enhancing decomposition efficiency of organic compounds. In this paper, the effect of ultrasonic frequency, ultrasonic intensity and pH value on 3-chlorophenol decomposition were studied. It was found that 3-chlorophenol in aqueous solution can be markedly decomposed by ultrasound assisted electrocatalytic process. The rate of decomposition increased with the increase of frequency, and low frequency is proper in the ultrasound assisted electrocatalytic system. The removal of 3-chlorophenol increased visibly with the increase of ultrasonic intensity until the intensity of 1.56 W/cm2. Alkaline condition is beneficial to 3-chlorophenol decomposition, the rate at pH 9.08 was higher than pH 2.48 and 6.85. The major intermediate formed during 3-chlorophenol decomposition was 2-chloro-pbenzoquinone, which was readily decomposed by ultrasound assisted electrocatalytic process.

Prediction of Compressive Strength Using Ultrasonic Pulse Velocity for CLSM with Waste LCD Glass Concrete

The purpose of this paper is to develop a prediction model of WGCLSM （waste LCD （liquid crystal display） glass controlled low strength materials） concrete, the relationship between UPV （ultrasonic pulse velocity） and compressive strength, UPV-strength model. The power function was used to perform the nonlinear-multivariate regression analysis of UPV with water-binder ratio （w/b）, curing age （t） and waste glass content （G） in our previous study. Test results show that the compressive strength increases with UPV and approach to a linear relationship. Thus, the UPV-strength model was established by linear-multivariate regression analysis and the compressive strength evaluated by ultrasonic pulse velocity. The calculated results are in accordance with the laboratory measured data ultrasonic pulse velocity and compressive strength. In addition, the statistical analysis shows that the coefficient of determination R2 and the MAPE （mean absolute percentage error） were from 0.916 to 0.951 and 12.6% to 15.1% for the compressive strength, respectively. The proposed models are highly accurate in predicting the compressive and ultrasonic pulse velocity of WGCLSM concrete. However, with other ranges of mixture parameters, the predicted models must be further studied.

Analysis on the mechanism and characteristics of concrete strength testing methods

This paper mainly described five kinds of common detection methods, including the test block method, core drilling method, rebound method, dialing out method and ultrasonic testing method and systematically analyzed the mechanism of all kinds of concrete strength detection methods as well as their advantages and disadvantages, which would provide a guide for construction personnel and research institutions to choose an economical ,accurate and safe detection method.

An Automated Ultrasonic NDT System for In-Situ Inspection of Wind Turbine Blades

It is crucial to maintain wind turbine blades regularly, due to the high stress leading to defects or damage. Conventional methods require shipping the blades to a workshop for off-site inspection, which is extremely time-consuming and very costly. This work investigates the use of pulse-echo ultrasound to detect internal damages in wind turbine blades without the necessity to ship the blades off-site. A prototype 2D ultrasonic NDT （non-destructive testing） system has been developed and optimised for in-situ wind turbine blade inspection. The system is designed to be light weight so it can be easily carried by an inspector onto the wind turbine blade for in-situ inspection. It can be operated in 1D A-scan, 2D C-scan or 3D volume scan. A software system has been developed to control the automated scanning and show the damage areas in a 2D/3D map with different colours so that the inspector can easily identify the defective areas. Experiments on GFRP （glass fibre reinforced plastics） and wind turbine blades （made of GFRP） samples showed that internal defects can be detected. The main advantages of this system are fully automated 2D spatial scanning and the ability to alert the user to the damage of the inspected sample. It is intended to be used for in-situ inspection to save maintenance time and hence considered to be economically beneficial for the wind energy industry.

Linear and Nonlinear Ultrasonic Detections of Impact Damage in Composite Laminate

The appearance and accumulation of internal impact damage seriously influence overall performance of carbon fiber reinforced plastic(CFRP).Thus,this study evaluates the change in impact damage number by using linear and nonlinear ultrasonic Lamb wave detection methods,and compares these two detection results.An ultrasonic wave simulation model for composite structure with impact damage is established using the finite element method,and the interaction between impact damage and the ultrasonic wave is simulated.Simulation results demonstrate that the ultrasonic amplitude linearly decreases,and the relative nonlinear parameter linearly increases in proportion to the impact number,respectively.The linear-fitting slope of nonlinear parameter is 0.38 per impact number at an input frequency of 1.0 MHz.It is far higher than that of the linear ultrasonic amplitude,which is only-0.12.However,with the increase of impact damage,the linear growth of nonlinear parameters mainly depends on the decrease in ultrasonic amplitude rather than the accumulation of second harmonic amplitude.In the linear ultrasonic amplitude detection,the linear fitting slope at 1.1 MHz is-0.14,which is lower than those at 0.9 MHz and 1.0 MHz.Meanwhile,in the nonlinear ultrasonic parameter detection,the linear fitting slope at 1.1 MHz is 0.92,which is higher than those at 0.9 MHz and 1.0 MHz.The results show that higher frequencies lead to greater attenuation of ultrasonic amplitude and a larger increase in nonlinear parameters,which can enhance the sensitivity of both linear and nonlinear ultrasonic detections.The accuracy of simulation results is demonstrated through the low-velocity impact and ultrasonic experiments.The results show that compared with nonlinear ultrasonic technology,the linear ultrasonic technology is more suitable for impact damage assessment of carbon fiber reinforced plastic because of its simpler detection process and higher sensitivity.

Shock Wave Strength Reduction by Passive Control Using Perforated Plates

Strong, normal shock wave, terminating a local supersonic area on an airfoil, not only limits aerodynamic performance but also becomes a source of a high-speed impulsive helicopter noise. The application of a passive control system （a cavity covered by a perforated plate） on a rotor blade should reduce the noise created by a moving shock. This article covers the numerical implementation of the Bohning/Doerffer transpiration law into the SPARC code and includes an extended validation against the experimental data for relatively simple geometries of transonic nozzles. It is a first step towards a full simulation of a helicopter rotor equipped with a noise reducing passive control device in hover and in forward flight conditions.