Investigation of Cavitation in NaCl Solutions in a Sonochemical Reactor Using the Foil Test Method

Ultrasonic baths and sonochemical reactors are widely used in industrial applications dealing with surface cleaningand chemical synthesis. The processes of erosion, cleaning and structuring of the surface can be typically controlledby changing relevant influential parameters. In particular, in this work, we experimentally investigate theeffect of NaCl concentration (0–5.5 mol/L) on the erosion of an aluminum foil under ultrasonic exposure at afrequency of 28 kHz. Special attention is paid to the determination of cavitation zones and their visualizationusing heat maps. It is found that at low NaCl concentration (0.3 mol/L), the foil destruction rate is higher thanin distilled water. At higher concentrations of salt, cavitation takes place mainly in the upper part of the container.

Corneal endothelial cells and acoustic cavitation in phacoemulsification

Postoperative complications of phacoemulsification,such as corneal edema caused by human corneal endothelial cell(CEC)injury,are still a matter of concern.Although several factors are known to cause CEC damage,the influence of ultrasound on the formation of free radicals during surgery should be considered.Ultrasound in aqueous humor induces cavitation and promotes the formation of hydroxyl radicals or reactive oxygen species(ROS).ROS-induced apoptosis and autophagy in phacoemulsification have been suggested to significantly promote CEC injury.CEC cannot regenerate after injury,and measures must be taken to prevent the loss of CEC after phacoemulsification or other CEC injuries.Antioxidants can reduce the oxidative stress injury of CEC during phacoemulsification.Evidence from rabbit eye studies shows that ascorbic acid infusion during operation or local application of ascorbic acid during phacoemulsification has a protective effect by scavenging free radicals or reducing oxidative stress.Both in experiments and clinical practice,hydrogen dissolved in the irrigating solution can also prevent CEC damage during phacoemulsification surgery.Astaxanthin(AST)can inhibit oxidative damage,thereby protecting different cells from most pathological conditions,such as myocardial cells,luteinized granulosa cells of the ovary,umbilical vascular endothelial cells,and human retina pigment epithelium cell line(ARPE-19).However,existing research has not focused on the application of AST to prevent oxidative stress during phacoemulsification,and the related mechanisms need to be studied.The Rho related helical coil kinase inhibitor Y-27632 can inhibit CEC apoptosis after phacoemulsification.Rigorous experiments are required to confirm whether its effect is realized through improving the ROS clearance ability of CEC.

Therapeutic ultrasound cavitation and its free radical ESR determination

The formation of free radicals OH and H in a naturally air-saturated aqueous solution exposed to therapeutic CW ultrasound at a frequency of 820 kHz has been confirmed by using spin trapping 5, 5-dimethyl-1-pyrroline-1-oxide ( DMPO ) and electron spin resonance ( ESR) technique . It is suggested that these radicals are formed due to the high temperature and pressure produced by the ultrasonic transient cavitation. The transient cavitation threshold is found at 0. 537-0.632W/cm2 under a sonication time of 3 minutes .With increasing sound intensity the yield of free radicals OH raises rapidly at the intensity ranging from 1-2W/ cm2, and no longer increase is observed at above 3W/cm2. The sound intensity (Ⅰ) dependence of the yield of OH(D) can be approximately described by a regression equation: D = 8.1(I1/2 -Ic1/2 )1/2 where Ic=0. 667W/ cm2 . Under a fixing sound intensity the yield of OH increases monotonously with the sonication time.

Ultrasound-mediated transdermal drug delivery of fluorescent nanoparticles and hyaluronic acid into porcine skin in vitro

Transdermal drug delivery （TDD） can effectively bypass the first-pass effect. In this paper, ultrasound-facilitated TDD on fresh porcine skin was studied under various acoustic parameters, including frequency, amplitude, and exposure time. The delivery of yellow-green fluorescent nanoparticles and high molecular weight hyaluronic acid （HA） in the skin samples was observed by laser confocal microscopy and ultraviolet spectrometry, respectively. The results showed that, with the application of ultrasound exposures, the permeability of the skin to these markers （e.g., their penetration depth and concentration） could be raised above its passive diffusion permeability. Moreover, ultrasound-facilitated TDD was also tested with/without the presence of ultrasound contrast agents （UCAs）. When the ultrasound was applied without UCAs, low ultrasound frequency will give a better drug delivery effect than high frequency, but the penetration depth was less likely to exceed 200 p.m. However, with the help of the ultrasound-induced microbubble cavitation effect, both the penetration depth and concentration in the skin were significantly enhanced even more. The best ultrasound-facilitated TDD could be achieved with a drug penetration depth of over 600 p.m, and the penetration concentrations of fluorescent nanoparticles and HA increased up to about 4-5 folds. In order to get better understanding of ultrasound-facilitated TDD, scanning electron microscopy was used to examine the surface morphology of skin samples, which showed that the skin structure changed greatly under the treatment of ultrasound and UCA. The present work suggests that, for TDD applications （e.g., nanoparticle drug carriers, transdermal patches and cosmetics）, protocols and methods presented in this paper are potentially useful.

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.

Effects of Pulse Ultrasound on Adsorption of Geniposide on Resin 1300 in a Fixed Bed

The effects of pulse ultrasound with different pulse parameters on the breakthrough curves of Geniposide on Resin 1300 were studied. The mass transfer model describing the adsorption process was constructed. Adsorption capability and the overall mass-transfer coefficient were obtained by fitting the constructed mass-transfer model and the experimental data. The effects of pulse ultrasound on adsorption of Geniposide on Resin1300 in a fixed bed were studied and compared. Amount of Geniposide adsorbed on Resin 1300 in the presence of ultrasound is lower than that in the absence of ultrasound, but the mass-transfer rate with ultrasonic irradiation is higher than that without ultrasound. Furthermore, mass transfer rate is enhanced by pulse modulation. In the conditions studied, the adsorption equilibrium constant decreases with increasing ultrasonic power, while the overall mass-transfer co-efficient increases. With increasing pulse duty ratio, adsorption equilibrium constant decreases initially, reaches a minimum when pulse duty ratio is 0.5, and then increases. On the contrary, the overall mass-transfer coefficient in-creases initially and reaches a maximum when pulse ratio is 0.5, and then decreases. Effects of pulse period on ad-sorption equilibrium and mass transfer rate reached the peak at pulse period of 28.6 ms.

Different Effects of Therapeutic Ultrasound Parameters and Culture Conditions on Gene Transfection Efficiency

Objective： To investigate the effect of different therapeutic ultrasound （TUS） parameters and culture conditions on the cell viability and transfection efficiency of human cervical cancer cells （HeLa）. Methods： HeLa cells were cultured using two different protocols （in suspension or in monolayer）. Subsequently, cells were exposed to different TUS intensity （0.4 W/cm^2, 1.0 W/cm^2, 1.6 W/cm^2, 2.2 W/cm^2）, duty cycle （DC）（10%, 20%, 50%）, exposure time （1 min or 3 min）. Cell viability was analyzed by flow cytometry. Gene transfection of red fluorescent protein （DsRED） was detected. Results： TUS intensity and duty cycle had a great impact on the overall results （P〈0.01）. Cell injury were found to increase progressively with intensity （1.6 W/cm^2, 2.2 W/cm^2） and duty cycle （50%） and cell detachment was accompanied by ultrasound exposure in adherent cells Results of factorial design showed that the fashion of cell culture and the TUS parameters had interaction （P〈0.01）. The ideal conditions that cell viability above 80% producing maximum efficiency were noted to be at 1.0 W/cm^2 irradiated 3 min with a duty cycle of 20% in cell suspension. Conclusion： TUS parameters and transfection conditions have a great impact on the gene transfection and cell viability. Optimal parameters could enhance cell inembrane permeability, which facilitate to delivering the macromolecules into cells.

Investigation and evaluation of ultrasound reactor for reduction of fungi from sewage

The objective of the investigation was to study the application of ultrasound reactor technology (USRT) as a disin-fectant for reduction of fungi from sewage effluent. Fungi are carbon heterotrophs that require preformed organic compounds as carbon sources. USRT is an attractive means to improve water quality because of the system simplicity and no production of toxic by-products. An ultrasound reactor produces strong cavitation in aqueous solution causing shock waves and reactive free radicals by the violent collapse of the cavitation bubble. These effects should contribute to the physical disruption of microbial structures and inactivation of organisms. There was significant reduction in fungal growth, with decreased fungal growth with increasing USRT. In this study, ultrasound irradiation at a frequency of 42 kHz was used to expose suspensions of fungi to evaluate the disinfection efficacy of the ultrasound reactor. Also, this study showed that in this system more than 99% reduction of sewage fungi was achieved after 60 min.

Nonlinear response of ultrasound contrast agent microbubbles:From fundamentals to applications

Modelling and biomedical applications of ultrasound contrast agent （UCA） microbubbles have attracted a great deal of attention. In this review, we summarize a series of researches done in our group, including （i） the development of an all-in-one solution of characterizing coated bubble parameters based on the light scattering technique and flow cytometry; （ii） a novel bubble dynamic model that takes into consideration both nonlinear shell elasticity and viscosity to eliminate the dependences of bubble shell parameters on bubble size; （iii） the evaluation of UCA inertial cavitation threshold and its relationship with shell parameters; and （iv） the investigations of transfection efficiency and the reduction of cytotoxicity in gene delivery facilitated by UCAs excited by ultrasound exposures.

Advances in microbubble-assisted ultrasound-guided gene therapy:Mechanisms and applications

Gene therapy,as one of the popular therapies nowadays,has been applied with great success in various diseases.Nevertheless,there are also concerns about the safety,therapeutic efficacy,and applicability of gene therapy.Microbubble-assisted ultrasound-guided gene therapy offers the following incomparable advantages over conventional methods.Initially,this strategy enables the therapeutic nucleic acids to effectively cross the barriers like cell membrane,blood-brain barrier,and blood-retinal barrier that exist in the body and reach regions that cannot be accessed by conventional methods,which extends the scope of applications of gene therapy.Next,it is possible to restrict the zone of gene transfection to the lesion area by controlling the irradiation coverage of ultrasound,hence effectively controlling the risk of off-targeting.Additionally,with the support of various imaging techniques like ultrasound imaging and magnetic resonance imaging,the procedure of gene therapy can be under image guidance,which will dramatically improve the safety of gene therapy.This review will highlight on the advances in ultrasound-enhanced gene delivery strategy,attention to the relevant mechanisms of the strategy,the derived technologies and the related cutting-edge applications.Moreover,we will also have a discussion on the limitations and future prospects associated with this gene delivery strategy.

CACA guidelines for ultrasound hyperthermia for oral and maxillofacial head and neck squamous cell carcinoma

Most of the patients with oral and maxillofacial malignancy are in the middle and advanced stages at diagnosis and the incidence rate is increasing in recent years.Chemotherapy alone is difficult to benefit the survival of patients with advanced oral and maxillofacial malignancy.Ultrasound hyperthermia is a new and effective treatment for malignant tumor,which is developing rapidly in addition to conventional treatment.However,at present,ultrasound hyperthermia has not been widely used in the treatment of oral and maxillofacial malignancy.Therefore,formation of a guideline on ultrasound hyperthermia for oral and maxillofacial malignancy is mandatory,in order to promote and standardize the clinical practice of ultrasound hyperthermia in this field,and improve the long-term survival rate and quality of life of patients.

A Numerical Investigation of the Effect of Boundary Conditions on Acoustic Pressure Distribution in a Sonochemical Reactor Chamber

The intensification of physicochemical processes in the sonochemical reactor chamber is widely used in problems of synthesis,extraction and separation.One of the most important mechanisms at play in such processes is the acoustic cavitation due to the non-uniform distribution of acoustic pressure in the chamber.Cavitation has a strong impact on the surface degradation mechanisms.In this work,a numerical calculation of the acoustic pressure distribution inside the reactor chamber was performed using COMSOL Multiphysics.The numerical results have revealed the dependence of the structure of the acoustic pressure field on the boundary conditions for various thicknesses of the piezoelectric transducer.In particular,the amplitude of the acoustic pressure is minimal in the case of absorbing boundaries,and the attenuation becomes more significant as the thickness of the piezoelectric transducer increases.In addition,reflective boundaries play a significant role in the formation and distribution of zones of maximum cavitation activity.

诊断超声激励微泡空化增强胰腺癌血流灌注的临床研究

目的 探讨诊断超声激励微泡空化对胰腺癌血流灌注的增强效应。方法 选取经病理组织学或细胞学证实的晚期胰腺癌患者21例,在每次临床化疗结束后120 min内对病灶进行诊断超声激励微泡空化治疗,空化治疗前后分别行超声造影动态观察肿瘤血流灌注情况,并根据肿瘤区域时间-强度曲线分析峰值强度(PI)、曲线下面积(AUC),比较空化治疗前后各指标的差异。结果 21例胰腺癌患者共计进行84次化疗联合诊断超声激励微泡空化治疗,治疗后胰腺癌病灶PI由(109.19±2.64)dB增加到(110.62±2.70)dB,AUC由(4752.76±149.53)dB·s增加到(4863.67±159.77)dB·s,但与治疗前比较差异均无统计学意义(P=0.16、0.33)。结论 诊断超声激励微泡空化可能会增加胰腺癌的血流灌注量,有望改善胰腺癌因乏氧、乏血供导致的化疗抵抗问题。

子宫附腔畸形的超声诊断及误诊原因分析

目的探讨子宫附腔畸形(accessory cavitated uterine malformation,ACUM)的超声声像图特征,并分析误诊原因,以加强对本病的认识,提高超声医师的诊断能力。方法收集2013年12月—2023年12月于北京协和医院就诊,并经手术病理确诊为ACUM的患者临床、病理及影像学资料,分析其超声特征、首诊误诊原因。结果共11例患者纳入本研究,平均确诊年龄(27.1±7.4)岁,平均初潮(6.1±5.5)年后出现痛经。术前超声显示ACUM均为单一病灶,位于圆韧带附着处下方子宫肌层内,平均最大直径(3.0±1.0)cm。病灶整体呈形态规则的厚壁囊实性结构,多数呈圆形或椭圆形(90.9%,10/11),边界清晰(72.7%,8/11),且与宫腔不相通(100%,11/11)。所有病灶内部均为囊性空腔,多呈磨玻璃样改变(90.9%,10/11),囊腔内衬呈内膜样线状高回声(90.9%,10/11)。病灶周边均由肌层样低回声或中等回声包绕,彩色多普勒超声示周边环状或半环状血流信号。所有患者均未合并腺肌症等其他子宫病变。误诊分析:11例患者中,首次超声正确诊断6例,首次MRI正确诊断5例,其中2例MRI误诊为残角子宫而超声检查均提示ACUM且双侧宫角可见。结论ACUM具有特征性的超声声像图表现,当年轻女性出现进行性痛经,超声于一侧圆韧带下方子宫肌层内探及形态规则的厚壁囊实性包块时,需考虑ACUM可能。

超声空化驱动石英玻璃表面液态Ga铺展机制研究

在不同超声振幅下进行液态Ga在石英玻璃表面的铺展实验,采用CCD摄影记录仪观察并记录其过程。发现随着超声波振幅的增大,液态Ga的铺展速度和最大铺展面积均增大,并伴有雾化现象。采用Matlab软件求解液态Ga内空化泡壁的运动方程,对空化泡的成长与破裂进行数值模拟分析。结果表明,空化泡初始半径增大,空化阈值下降,液态Ga的表面张力降低,空化效应容易发生。超声波振幅和空化泡的初始半径的增大均会促进在液态Ga中产生空化效应,从而去除液态Ga表面的氧化膜,促进其铺展。

超声联合微泡对神经血管单元的作用机制研究进展

超声联合微泡是一种新兴技术,可将各种治疗药物输送到大脑,其通过空化效应促进脑组织中内皮细胞增殖,诱导血管生成,加速Aβ淀粉样斑块清除,增强神经发生以及改善动物的认知功能,作用的靶点包括参与血脑屏障形成的神经血管单元的所有细胞。这些作用在脑血管病、中枢神经系统肿瘤、帕金森病以及阿尔茨海默病等脑部疾病的治疗方面有着重要的临床价值。本文就超声联合微泡对神经血管单元的作用机制及其研究进展进行综述。

超声激励微泡空化在新型辅助治疗中的应用及进展

超声激励微泡空化(USMC)是超声场中震荡微泡引发的空化现象,该效应已在提高细胞膜的通透性、增强肿瘤细胞对化疗或免疫治疗的敏感性及增加溶栓药物对血栓渗透和血管再通方面取得了突破性进展。近年来,超声医学与材料学的交叉融合催生了超声响应性多功能纳米级微泡的研究,提升了USMC治疗效果。本文综述了USMC在改善缺血疾病的组织灌注、肿瘤化疗和免疫治疗、超声溶栓等方面的应用及研究进展。

聚焦超声作用下空化活动演变及其监测方法

高强度聚焦超声是实现肿瘤热消融的有效治疗方式。对超声治疗过程中的空化活动进行实时监测,对于保障治疗的安全性和有效性具有重要意义。该研究搭建了聚焦超声作用下仿生物组织体模和离体牛肝组织的被动空化检测和驱动功率监测系统,并使用显微镜记录了体模在超声作用过程中气泡和损伤的发展过程,分析了气泡发展过程与空化信号变化的相关性。实验表明:体模在电功率150 W的超声辐照过程中,沸腾气泡产生前未见宽带噪声幅值增加;6 s时体模内产生沸腾气泡,气泡破裂后产生大量空化核并形成空化泡群,宽带噪声幅值开始增长,此后泡群逐渐向换能器方向发展;在泡群停止向换能器端发展后,靠近换能器端的微小气泡逐渐融合产生沸腾气泡,惯性空化强度在沸腾气泡屏蔽下逐渐下降;沸腾泡产生和破灭时,驱动功率和回波信号中的谐波幅值同步出现大幅波动;在离体牛肝组织中,随声强的增加沸腾空化发生时刻逐渐提前。实验结果证明了沸腾气泡的产生及破裂,会促进惯性空化的发生。因此在不同强度的聚焦超声辐照下,可以通过调节辐照时间避免剧烈空化活动发生。

舰船超声波防海生物污损技术应用试验研究

针对舰船的海生物腐蚀污染问题,对超声波防海生物污损技术在海水阀箱、螺旋桨上的应用进行试验研究,同时检验超声波装置对海水阀箱、螺旋桨金属材料力学拉伸和冲击性能的影响。结果表明:在63天的试验周期内,超声波防污技术对海生物的生长与附着有一定的抑制作用,对海水阀箱、螺旋桨金属材料的力学性能、冲击性能和表面涂层性能等基本无影响。研究结果证明了超声波防海生物技术的价值,并排除了应用风险,对舰船超声波防海生物技术的实船应用具有一定的指导意义。

HIFU治疗中换能器驱动电功率变化机制及规律

高强度聚焦超声(HIFU)治疗中的驱动电功率对治疗效率起着非常关键的作用,驱动电功率控制的精准性势必会影响治疗的效率和安全性。前期研究表明:HIFU治疗过程中焦域瞬态物理特性的变化会导致换能器的负载阻抗发生变化,进而影响HIFU驱动电功率,但驱动电功率与焦域瞬态物理特性之间的影响关系及规律尚不明确。该文基于电压、电流传感器、空化检测探头和温度传感器等器件,构建了一种HIFU治疗中驱动电功率实时监测及焦域声空化、温度检测系统。基于该实验研究系统,以离体牛心组织作为HIFU辐照对象,分别研究了HIFU焦域温度变化、声空化及组织损伤与驱动电功率之间的变化关系及规律。研究结果表明:当焦域温度升高时,驱动电功率缓慢上升,驱动电功率与温度变化有良好的相关性;当空化产生时,驱动电功率出现明显的波动;当组织出现损伤时,驱动电功率呈陡然下降的变化。三种情景下,驱动电功率变化有明显区别,这有望为区分HIFU治疗过程中焦域处发生损伤和空化以及实时监测靶组织损伤程度提供一种新的解决方案。