Effect of Micro-electrolysis and Micro-nano Bubbles Coupled with Peroxymonosulfate Treatment of Rural Domestic Sewage

With the continuous deepening of rural revitalization strategy and the increasingly strict sewage discharge standards,rural domestic sewage treatment technology is facing higher challenges and requirements.The combined process of micro-electrolysis+micro-nano bubbles coupled with peroxymonosulfate was constructed in this study,and the treatment effect and application value of this technology were explored with the actual rural domestic sewage as the treatment object.The experimental results showed that under the conditions of HRT of 120 min,PMS dosage of 0.15 mmol/L,pH=7,MBs air intake of 15 ml/min,current intensity of 15 A,and Fe/C mass ratio of 1:1,the removal rates of COD,ammonia nitrogen and total phosphorus can reach 88.55%,77.18%and 74.67%,respectively.Under the condition that the pH value of sewage was not adjusted,the non-biochemical simultaneous decarbonization,denitrification and phosphorus removal of rural domestic sewage can be achieved by micro-electrolysis and micro-nano bubbles coupled with peroxymonosulfate.The concentrations of effluent COD,ammonia nitrogen and total phosphorus met the requirements of the first level standard of the Discharge Standard of Water Pollutants for Rural Domestic Sewage Treatment Facilities(DB45T2413-2021).And the comprehensive operating cost was about 1.15 yuan/m 3.

Dynamic modeling of cavitation bubble clusters:Effects of evaporation,condensation,and bubble-bubble interaction

We present a dynamic model of cavitation bubbles in a cluster,in which the effects of evaporation,condensation,and bubble-bubble interactions are taken into consideration.Under different ultrasound conditions,we examine how the dynamics of cavitation bubbles are affected by several factors,such as the locations of the bubbles,the ambient radius,and the number of bubbles.Herein the variations of bubble radius,energy,temperature,pressure,and the quantity of vapor molecules are analyzed.Our findings reveal that bubble-bubble interactions can restrict the expansion of bubbles,reduce the exchange of energy among vapor molecules,and diminish the maximum internal temperature and pressure when bursting.The ambient radius of bubbles can influence the intensities of their oscillations,with clusters comprised of smaller bubbles creating optimal conditions for generating high-temperature and high-pressure regions.Moreover,an increase in the number of bubbles can further inhibit cavitation activities.The frequency,pressure and waveform of the driving wave can also exert a significant influence on cavitation activities,with rectangular waves enhancing and triangular waves weakening the cavitation of bubbles in the cluster.These results provide a theoretical basis for understanding the dynamics of cavitation bubbles in a bubble cluster,and the factors that affect their behaviors.

Synergistic Treatment of Low-concentration Organic Waste Gas by Micro-nano Bubble Coordinated with Peroxymonosulfate

Continuous dynamic experiment was conducted for the treatment of low-concentration organic waste gas with xylene as a representative, using micro-nano bubble and peroxymonosulfate working in synergy. The degradation rule of xylene under different conditions such as the ORP value of the spray liquid, pH value of the spray liquid, liquid-gas ratio of the spray liquid, residence time of xylene, and initial concentration of xylene was investigated. The results showed that at a low concentration, the pH value of the spray liquid had little effect on the degradation rate of xylene. The degradation rate of xylene rose with the increase of the ORP value of the spray liquid, the liquid-gas ratio of the spray liquid, the residence time of xylene, and the initial concentration of xylene.

Effects of vapour bubbles on acoustic and temperature distributions of therapeutic ultrasound

This paper describes the evolution of vapour bubbles and its effect on nonlinear ultrasound propagation and temperature rise through tissues for therapeutic ultrasound. An acoustic-thermo coupling algorithm incorporating nonlinearity, diffraction, and temperature-dependent tissue properties, is employed to describe nonlinear ultrasound propagation and thermal effect. Results demonstrate that an obvious migration of peak pressure toward transducer surface is observed while the position of peak temperature changes little in liver tissue before the generation of vapour bubbles, and that the boiling region enlarges towards the surface of transducer in axial direction but increases slowly in radial direction after the generation of vapour bubbles.

Theoretical analysis of interaction between a particle and an oscillating bubble driven by ultrasound waves in liquid

A theoretical model is developed to describe the interaction of a particle and an oscillating bubble at arbitrary separation between them. The derivation of the model is based on the multipole expansion of the particle and bubble velocity potentials and the use of Lagrangian mechanics. The model consists of three coupled ordinary differential equations. One of them accounts for the pulsation of the bubble and the other two describe the translation of the bubble and particle in an infinite, incompressible liquid. The model here is accurate to order 1/d^10, where d is the distance between the centers of the particle and bubble. The effects of the size and density of the particle are investigated, namely, the interaction between the particle and bubble changes from repulsion to attraction with the increment of the particle density, and the increment of the particle size makes the interaction between the particle and bubble stronger. It is demonstrated that the driving frequency and acoustic pressure amplitude can affect the interaction of the particle and bubble. It is shown that the correct modeling of the translational dynamics of the bubble and particle at small separation distances requires terms accurate up to the tenth order.

Development of cell-targeting bubble liposome for effective gene delivery with ultrasound

Previously,we developed a gene delivery system using Bubble liposomes(perfluoropropane gas-entrapping liposomes;BLs)and ultrasound(US)[1].The combination of BLs and US can deliver plasmid DNA into the cytoplasm via the formation of transient membrane pores by cavitation.To enhance the efficiency of gene delivery,it is important to induce the cavitation of BLs at the vicinity of cells.In brief,cell-binding BLs would be useful for gene delivery to induce the cavitation on the cell membrane.

On the possible ultrasonic inspection of micro-bubbles generated by the optical fiber tip

We demonstrate the possibility of detection and monitoring of bubbles emerging near the tip of an optical fiber by means of ultrasonic method.The excitation of bubbles at their resonant frequencies is performed using short ultrasonic pulses having a wide frequency range simulta-neously with their modulation by means of a long pulse of a monochromatic frequency.This method allows detection of bubbles of various sizes.Used signal processing method,which allows increased bubble detection accuracy,is proposed for ressearch in envir onments of biological-like medium which show continuous variations in structure and properties when exposed to optical emission.The method has been demonstrated on model objects:in a liquid and in a biological tissue phantom using various methods of bubble generation(hydrolysis and optical enission).We studied bubble formation by the tip of a fiber of the surgical laser LSP-007/10 "IRE Polus"with a wavelength of 0.97μm coated with a highly absorbing graphite layer.

Bubble Size Measurement by the Ultrasonic Pulse Echo with Tracking Technique

Bubbly flows appear in many different industrial fields and the measurement of bubble sizes is crucial for understanding phase interactions. The ultrasound pulse echo can be used for a non-intrusive measurement of the bubble surface position in one dimension even when there is no optical access to the bubble. A simultaneous measurement from two opposing directions gives the bubble size but has been performed only on single bubbles. This work applies the tracking technique, which allows a simultaneous measurement of multiple bubbles. The performance of the bubble size measurement was tested experimentally by comparing ultrasonic results with the sizes measured by a high-speed camera and also with metal cylinders. Possible sources of measurement uncertainty were analysed and discussed. The tested range of bubble sizes was up to 10 mm and the void fraction was lower than 1.25%.

Interaction between encapsulated microbubbles:A finite element modelling study

Theoretical studies on the multi-bubble interaction are crucial for the in-depth understanding of the mechanism behind the applications of ultrasound contrast agents （UCAs） in clinics. A two-dimensional （2D） axisymmetric finite element model （FEM） is developed here to investigate the bubble-bubble interactions for UCAs in a fluidic environment. The effect of the driving frequency and the bubble size on the bubble interaction tendency （viz., bubbles＇ attraction and repulsion）, as well as the influences of bubble shell mechanical parameters （viz., surface tension coefficient and viscosity coefficient） are discussed. Based on FEM simulations, the temporal evolution of the bubbles＇ radii, the bubble-bubble distance, and the distribution of the velocity field in the surrounding fluid are investigated in detail. The results suggest that for the interacting bubble-bubble couple, the overall translational tendency should be determined by the relationship between the driving frequency and their resonance frequencies. When the driving frequency falls between the resonance frequencies of two bubbles with different sizes, they will repel each other, otherwise they will attract each other. For constant acoustic driving parameters used in this paper, the changing rate of the bubble radius decreases as the viscosity coefficient increases, and increases first then decreases as the bubble shell surface tension coefficient increases, which means that the strength of bubble-bubble interaction could be adjusted by changing the bubble shell visco-elasticity coefficients. The current work should provide a powerful explanation for the accumulation observations in an experiment, and provide a fundamental theoretical support for the applications of UCAs in clinics.

耦合超声场的气液流动特性

功率超声作为一种新兴的绿色技术,越来越受到石油行业的重视。结合稠油超声降黏机制,从气泡瞬态演化规律和溃灭特性出发,对超声作用下空化气泡和空化流场进行数值模拟和实验验证。模拟结果表明,增加超声频率和减小气泡之间的距离会导致单个空化气泡最大半径的减小,气泡个数的增加会使气泡生长至破裂过程的速度减小,延长超声作用时间和增大超声频率可增加超声场中最大空化压力。实验表明,空化气泡不断在超声场中振荡并互相聚并,且随着超声作用时间的延长,该过程更加剧烈。研究内容为稠油超声降黏在石油化工行业的应用提供了重要的理论指导。

超声场中气泡运动规律及其与枝晶相互作用机制

采用有限元模拟和高速摄影实验研究了液体中单个气泡在超声作用下的振荡及溃灭规律,并揭示了气泡空化与邻近枝晶间的相互作用机制.结果表明,增大驱动声压促使气泡振荡模式由体积振荡转变为分裂振荡,从而显著地提升液体中的瞬态压强和流动速度.当气泡下方存在一个枝晶时,随着驱动声压的增加,二次分枝的断裂模式发生从高周疲劳断裂向低周疲劳断裂再到过载断裂的转变,且断裂周期呈幂函数下降趋势.气泡距离枝晶越近,压缩状态下气泡的纵向半径逐渐大于横向半径,且压缩时间增加,最小气泡体积降低.另外,气泡与枝晶距离的减小导致气泡溃灭产生的最大压强显著降低,而最大流速呈现先增大后降低的趋势.若二次分枝的根部半径减小或长度增加,二次分枝疲劳断裂周期数显著减小,从而更容易诱发枝晶碎断.理论计算的气泡膨胀收缩和二次分枝断裂过程与实验结果基本一致,表明本文构建的模型能够准确预测超声场中的气泡运动及其与枝晶相互作用过程.

Chemically-induced active micro-nano bubbles assisting chemical mechanical polishing:Modeling and experiments

The material loss caused by bubble collapse during the micro-nano bubbles auxiliary chemical mechanical polishing(CMP)process cannot be ignored.In this study,the material removal mechanism of cavitation in the polishing process was investigated in detail.Based on the mixed lubrication or thin film lubrication,bubble-wafer plastic deformation,spherical indentation theory,Johnson-Cook(J-C)constitutive model,and the assumption of periodic distribution of pad asperities,a new model suitable for micro-nano bubble auxiliary material removal in CMP was developed.The model integrates many parameters,including the reactant concentration,wafer hardness,polishing pad roughness,strain hardening,strain rate,micro-jet radius,and bubble radius.The model reflects the influence of active bubbles on material removal.A new and simple chemical reaction method was used to form a controllable number of micro-nano bubbles during the polishing process to assist in polishing silicon oxide wafers.The experimental results show that micro-nano bubbles can greatly increase the material removal rate(MRR)by about 400%and result in a lower surface roughness of 0.17 nm.The experimental results are consistent with the established model.In the process of verifying the model,a better understanding of the material removal mechanism involved in micro-nano bubbles in CMP was obtained.

基于超声-微纳米气泡辅助技术的可变光程水质多参数检测方法研究

针对目前国家标准分析检测水质多参数方法存在的科学与技术问题,提出了一种基于超声-微纳米气泡(US-MNB)辅助技术、连续光谱法和顺序注射分析法(SIA)的可变光程水质多参数检测新方法。设计水质多参数检测系统,通过检测总磷(TP)、化学需氧量(COD)、氨氮(NH_(3)-N)和六价铬(Cr^(6+))四种水质参数,验证了新方法的可行性。系统设计的核心是基于超声与微纳米气泡相结合的消解室以及具有可变光程功能的光谱扫描检测室,可达到快速消解和稳定检测的目的。同时系统基于国家水质检测标准,优化了水质多参数联合检测流程,并利用分光光度法和顺序注射分析技术对四种水质参数的含量进行连续光谱检测。首先,在常温常压下采用US-MNB辅助技术结合强氧化剂对TP进行消解,同时对检测室中NH_(3)-N参数显色反应后的化合物直接进行光谱扫描测定,消解后,再进行TP的测定。同理,消解COD的同时,对检测室中的Cr^(6+)参数显色反应后的化合物直接进行光谱扫描测定,消解后,再进行COD的测定。整个检测过程所用时间大幅降低,可在短时间内自动完成水质多参数的测定,显著地提高了检测的效率。以上述四种水质参数为测定对象,利用最小二乘法构建回归模型,拟合回归方程并计算相关系数,并绘制各参数的浓度-吸光度标准工作曲线。结果表明:TP标准工作曲线拟合系数≥0.9845,且浓度与吸光度成正相关,重复性(RSD)为3.05%~3.62%,加标回收率为97.8%~103.6%;COD标准工作曲线拟合系数≥0.9987,且浓度与吸光度成负相关,重复性(RSD)为2.12%~2.74%,加标回收率为98.7%~104.7%;NH_(3)-N标准工作曲线拟合系数≥0.9953,且浓度与吸光度成正相关,重复性(RSD)为3.41%~3.59%,加标回收率为99.2%~102.4%;Cr^(6+)标准工作曲线拟合系数≥0.9938,且浓度与吸光度成正相关,重复性(RSD)为3.51%~3.92%,加标回收率为98.9%~109.3%。系统可准确测定水样中TP、COD、NH_(3)-N和Cr^(6+)的含量,且具有良好的稳定性与可靠性。基于超声-微纳米气泡辅助技术的可变光程水质多参数检测方法研究,对于拓宽光谱法在水质多参数快速检测领域的应用以及提升检测效率等方面的研究具有重要作用。

High intensity focused ultrasound in clinical tumor ablation

Recent advances in high intensity focused ultrasound(HIFU),which was developed in the 1940s as a viable thermal tissue ablation approach,have increased its popularity.In clinics,HIFU has been applied to treat a variety of solid malignant tumors in a well-defined volume,including the pancreas,liver,prostate,breast,uterine fibroids,and soft-tissue sarcomas.In comparison to conventional tumor/cancer treatment modalities,such as open surgery,radio-and chemo-therapy,HIFU has the advantages of non-invasion,non-ionization,and fewer complications after treatment.Over 100 000 cases have been treated throughout the world with great success.The fundamental principles of HIFU ablation are coagulative thermal necrosis due to the absorption of ultrasound energy during transmission in tissue and the induced cavitation damage.This paper reviews the clinical outcomes of HIFU ablation for applicable cancers,and then summarizes the recommendations for a satisfactory HIFU treatment according to clinical experience.In addition,the current challenges in HIFU for engineers and physicians are also included.More recent horizons have broadened the application of HIFU in tumor treatment,such as HIFU-mediated drug delivery,vessel occlusion,and soft tissue erosion(“histotripsy”).In summary,HIFU is likely to play a significant role in the future oncology practice.

Environment-friendly surface cleaning using micro-nano bubbles

Cleaning a surface using a solution containing a large number of micro to nano scale bubbles has significant advantage regarding environmental protection.This review first briefly introduces the cleaning mechanism of micro-nano bubbles(MNBs),including physical and chemical effects.Then the applications of MNBs in cleaning of metal parts,precision parts,cultural relics or food are introduced.After that,coupled cleaning method of ultrasound and bubbles is introduced.Finally,the characterization methods for the cleaning effect are introduced,which mainly focuses on the changes of physico-chemical properties(mass or cleaning area,infiltration,colony number and light scattering intensity)of the cleaned parts or that(like conductivity)of the solvent.It is believed that MNBs technology will be applied in a broader range of surface cleaning applications.

经颅聚焦超声开放小鼠血脑屏障的脉宽筛选及可逆性研究

目的:利用聚焦超声(focused ultrasound,FUS)治疗系统,固定基础频率等其他参数,探索脉宽对FUS经颅开放血脑屏障(BBB)有效性及安全性的影响,筛选出合适的脉宽值,并验证FUS开放BBB的可逆性。方法:将73只SPF级昆明小鼠,随机分为脉宽筛选组(共45只)和可逆性研究组(28只)。脉宽筛选组又分为0ms组、1ms组、10ms组、100ms组和200ms组共5个亚组,用不同脉宽的FUS经颅辐照靶脑区后经尾静脉注射伊文思蓝(Evans blue,EB)溶液,4h后取材,对BBB开放与否进行定性评价并测量脑组织EB含量,辐照区域脑组织行HE染色;可逆性研究组分为4个亚组(每组7只):-1—0h组、0—1h组、1—8h组和8—9h组,分别于相应时间点进行FUS经颅辐照、EB注射,取材,对脑部EB含量进行测量。结果:0ms组小鼠BBB未开放,小鼠脑部EB含量为(4.67±2.14)μg/g,其余各组小鼠BBB均有不同程度开放。1ms、10ms、100ms、200ms组小鼠脑部EB含量分别为(9.63±3.31)μg/g、(19.16±2.47)μg/g、(20.75±7.77)μg/g、(29.48±10.42)μg/g,其中1ms、10ms、100ms、200ms组小鼠脑部EB含量与对照组(0ms组)相比有显著性意义,且10、100、200ms组BBB开放效率明显高于1ms组。0ms组、1ms组、10ms组小鼠FUS辐照中心区域脑组织未见红细胞渗出,100ms组、200ms组FUS辐照中心区域有少量红细胞渗出;-1—0h组、8—9h组小鼠BBB未开放,0—1h组、1—8h组小鼠BBB有不同程度开放。-1—0h组、0—1h组、1—8h组、8—9h组小鼠脑部EB含量分别为(1.50±0.19)μg/g、(8.60±1.89)μg/g、(2.63±0.76)μg/g、(1.57±0.46)μg/g。与对照组相比,0—1h组、1—8h组小鼠脑部EB含量明显增高。8—9h组与对照组相比无显著性意义,同时,0—1h组与其他各组相比均有显著性意义。结论:利用现有聚焦超声治疗系统,当FUS基础频率为1MHz,总辐照时间120s,输出电压200mV,脉冲重复频率为1Hz,SonoVue?六氟化硫微泡剂量2.5μl/g情况下,脉宽10ms可经颅、高效、安全开放BBB,是较为合适的脉宽值。该参数条件下FUS开放BBB是动态可逆的。

新型蔬菜清洗机的研制

分析了超声波和气泡作为蔬菜清洗动力的机理。设计制造了以超声波和气泡为清洗动力的蔬菜清洗试验机。以试验机为基础进行蔬菜清洗正交试验,确定了适合蔬菜清洗的工艺参数:超声波功率450W、气泡强度25m3/h、清洗时间4min。以此试验参数为依据研制了蔬菜清洗机。试验表明,该清洗机每小时清洗叶类蔬菜120kg以上,其洗净率大于95%,破损率小于2%;每小时清洗根茎类蔬菜240kg以上,其洗净率大于90%,破损率小于1%。

超声在有机反应中的应用

介绍了超声化学的原理和实验室常用的超声设备 .评述了超声在均、多相有机反应中的应用 .超声在均、多相反应中除可以提高反应速率 ,有时也可以改变反应路线 .在相转移催化反应体系中 ,超声能够取代相转移催化剂 。

超声场下刚性界面附近溃灭空化气泡的速度分析

为了揭示刚性界面附近气泡空化参数与微射流的相互关系,从两气泡控制方程出发,利用镜像原理,建立了考虑刚性壁面作用的空化泡动力学模型.数值对比了刚性界面与自由界面下气泡的运动特性,并分析了气泡初始半径、气泡到固壁面的距离、声压幅值和超声频率对气泡溃灭的影响.在此基础上,建立了气泡溃灭速度和微射流的相互关系.结果表明:刚性界面对气泡振动主要起到抑制作用;气泡溃灭的剧烈程度随气泡初始半径和超声频率的增加而降低,随着气泡到固壁面距离的增加而增加;声压幅值存在最优值,固壁面附近的气泡在该最优值下气泡溃灭最为剧烈;通过研究气泡溃灭速度和微射流的关系发现,调节气泡溃灭速度可以达到间接控制微射流的目的.

超声空化气泡运动的数值模拟

依据热力学和动力学分析,建立了声场作用下液体中一个气泡的运动模型。通过对运动方程的数值模拟,研究了液体中声压幅值、超声频率、空化核半径以及液体的密度、表面张力、动力粘度等因素对气泡运动的影响。