超声提取南瓜多糖的研究

南瓜多糖是南瓜的活性成分,具有保健、疗疾功效。通过实验研究了预浸时间、超声功率、超声提取温度,超声作用时间以及占空比对超声提取南瓜多糖的影响和效果。结果表明：以水为提取剂,预浸时间10min,超声作用时间20min,提取温度60℃,超声波功率80W,占空比为1时,样品中南瓜多糖提取量最大可达42．6mg／g。     

超声强化溶剂提取车前草中总黄酮的研究

采用超声技术对车前草中总黄酮提取进行强化,选择料液比、超声提取时间、提取温度、超声功率四因素进行正交实验,得出影响总黄酮提取率大小的次序先后为：提取温度〉超声功率〉超声提取时间〉料液比。在实验参数的基础上,为了获得较高的提取率和节省溶剂用量,各因素的优化工艺参数为：料液比1：20,超声提取时间30min,超声提取温度为50℃,超声功率为200W,在这个最佳条件下试验,总黄酮的提取率为0．645％。相对常规回流提取法而言,采用超声法提取具有快速、节省溶剂、节省时间、提取的有效成分含量较高等优点。     

双频超声强化从海金沙中提取黄酮的实验研究

采用双频超声强化从海金沙中提取黄酮的研究结果显示:在27℃,海金沙质量与乙醇体积比为0.05g/ml,搅拌器转速、超声功率及频率不变的条件下,质量浓度达到平衡时的60%,搅拌提取需700min以上,槽式超声需105min,探头式超声需45min,而双频超声所需时间不到20min;若提取时间均为60min,则双频超声的提取率为搅拌的11倍,为槽式超声的2倍,为探头式超声的1.8倍。通过选择乙醇浓度、溶剂用量、超声作用时间、浸泡时间因素进行正交实验,得出双频超声提取最佳工艺条件:浓度70%用量为40ml的乙醇,超声作用时间30min,浸泡时间为4h。机理探讨表明,当两束超声波同时传播时,超声作用的均匀性增强,声强增大,使得海金沙颗粒的边界层变薄,外表面剥落,甚至使其颗粒发生碎裂,传质速率大大提高,试验结果表现为双频超声对提取过程具有协同增强作用。     

RDX/Al/AP/HTPB炸药回收过程中AP提取工艺的响应面法优化

为了回收RDX/Al/AP/HTPB炸药中的高氯酸铵(AP),通过Design Expert 8.0软件进行了响应面实验设计,得出了该工艺的提取率模型,研究了提取时间、超声功率、表面活性剂质量分数等因素对AP提取过程的影响。分析数据得出AP提取工艺的最佳参数,并对其进行了实验验证。结果表明,二次回归模型的拟合方程为:Y=89.82+3.10A+2.65B+0.33C-0.25AB-0.45AC-0.15BC-0.06A2-1.31B2-0.26C2。各因素对提取率的影响程度由大到小为:提取时间、超声功率、表面活性剂质量分数。优化的工艺参数为:提取时间44 min,超声功率960W,表面活性剂质量分数1.7%,此时AP的提取率达90%以上。     

超声提取葵粕绿原酸研究

研究了超声强化提取葵粕绿原酸中主要参数-乙醇浓度、液料比、超声功率、超声辐照方式、超声提取时间以及超声提取次数等-对绿原酸萃取率的影响.通过在单因素实验基础上进行的三因素三水平的Box-Behnken实验,得到了优化的工艺条件:在乙醇浓度为70%、辐照方式占空比9s:6s、超声提取30min的条件下,液料比为27.3ml/g,超声功率为200W,提取3次,绿原酸的萃取率可达到98.87%.     

超声对提取海藻二十二碳六烯酸和二十碳五烯酸的影响

二十二碳六烯酸(DHA)和二十碳五烯酸(EPA)具有许多重要的生理活性和营养学功能。通过实验研究了提取温度、料液比、超声功率、频率以及提取时间对超声提取海藻DHA和EPA影响和超声提取的效果,结果表明,适当提高提取温度、溶剂量、超声功率或延长提取时间,DHA和EPA提取率随之提高。当超声功率为50W时,随着超声频率增加,DHA和EPA提取率反而降低。相同料液比时,55℃超声法提取1h比65℃溶剂法提取2h的DHA和EPA提取率提高25%～44%。不同料液比时,当料液比为1:4.5,超声法提取1h,DHA和EPA的提取率分别为79.48%、81.52%;而溶剂法料液比为1:5.5,提取2h时,DHA、EPA的提取率分别仅为63.57%、64.87%。超声提取不仅降低了提取温度、减少了提取时间和提取溶剂量,而且使DHA和EPA提取率明显提高。     

茭白苞叶中总黄酮提取及其体外抗氧化性能研究

运用超声波技术辅助提取茭白苞叶中的总黄酮,经正交实验得出茭白苞叶中总黄酮提取的最佳工艺参数:超声波功率700 W,温度60℃,料液比(g/mL)1∶60,乙醇质量分数浓度为60%,提取时间为35 min,茭白苞叶中总黄酮最大提取率为1.127%.采用抗坏血酸作为对照,全面测定了茭白苞叶总黄酮对超氧阴离子自由基、羟基自由基、DPPH自由基的清除率,以及还原能力、抗脂质过氧化活性和对食用油脂的抗氧化性的影响,结果表明,白苞叶中的总黄酮是一种有开发价值的天然抗氧化剂.     

超声波协同法提取荷叶中总黄酮的研究

采用超声波协同提取法对荷叶总黄酮进行提取,通过单因素试验确定最佳的荷叶总黄酮提取工艺：提取时间20min,料液比1：30,乙醇浓度60％,温度50℃,验证试验证明实际提取率为4．85％。     

超声强化废SCR催化剂浸出V和W的研究

废SCR催化剂的V和W的回收再利用具有巨大的社会、环境和经济效益。研究了碳酸钠焙烧-水浸法回收废SCR催化剂中的V和W,并引入超声波对浸出过程进行强化,同时还考察了超声时间、液固比、超声功率对超声浸出率的影响。结果表明,相对于常规搅拌浸出,超声强化提高了V和W的浸出率,缩短了浸出时间,超声浸出3 min时V的浸出率为76.92%,W的浸出率为69.87%,比常规搅拌条件下的分别提高23.08%和2.59%。超声强化浸出最佳工艺条件为超声时间90 min,液固比12∶1,超声功率500 W,最终V和W的浸出率分别为89.01%和96.05%。废SCR催化剂的V、W的溶解动力学符合Stumm方程,其中V的溶解反应属于一级反应,W的溶解反应属于二级反应。     

罗汉松种子总黄酮提取工艺优化及抗氧化活性

目的 采用响应面法优化罗汉松种子总黄酮超声提取工艺，并考查总黄酮的抗氧化活性。方法 基于单因素试验，以料液比、超声时间、超声温度为自变量，以总黄酮得率和DPPH自由基的清除率为因变量，采用三因素三水平的响应面分析法，确定最佳提取工艺条件。结果 得到最佳工艺参数：在超声频率为40 kHz、超声功率为200 W时，料液比（g/mL）为1∶50、超声温度为70℃、超声时间为2.7 h，其理论预测值总黄酮得率为27.54mg/g(n=3，相对标准偏差为1.63%)。当添加稀释10倍的总黄酮提取液0.50mL时，对DPPH自由基的清除率达到87.2%、对Ce（Ⅳ）还原率达到84.2%；当添加稀释10倍的总黄酮提取液0.90mL时，对OH自由基的清除率为88.1%。结论 采用响应面法优化得到的超声波辅助提取工艺稳定、可靠，可用于罗汉松种子总黄酮的提取。罗汉松种子总黄酮可作为优良的天然抗氧化剂资源。     

Ultrasound to decontaminate heavy metals in dredged sediments.

Sediments contaminated with heavy metals due to past disposal practices threaten the environment and require remediation. This study was an attempt to develop a technology to decontaminate heavy metals in dredged sediments using ultrasound coupled with vacuum pressure. A set of laboratory scale experiments were conducted using dredged sediments obtained from New York/New Jersey harbor. This sediment sample is considered as category III, a material that failed to meet USEPA requirements for toxicity or bioaccumulation, and required secure disposal. Acoustic cavitation due to ultrasound energy coupled with vacuum pressure was used to facilitate the removal of chromium (the selected metal contaminant) from the sediments. Full factorial experimental designs were performed to evaluate the above treatment technique and to optimize the processes. Two coupled processes were used to separate and to treat both coarse (Process #1) and fine (Process #2) fractions of sediments. Selected variables for evaluation of Process #1 were ultrasound power, soil-to-water ratio, vacuum pressure and dwell time, and for Process #2 were ultrasound power, soil-to-water ratio and dwell time. Laboratory scale experiments were carried out with various combinations of these parameters according to the factorial design. The optimum removal was found to be 92% with the parameter levels at 1200W power, 1:15 soil-to-water ratio, 15 psi vacuum pressure and 15 min of dwell time. After the application of Process #2 for fine sediments it was found that the fines were separated into silt and clay. Only the silt faction had a considerable metal removal while the clay fraction was insensitive to the treatment. A maximum removal of 83% was obtained for silt fraction when factor levels were at 1200W power, 1:50 soil-to-water ratio and 90 min of dwell time. Further analysis of clay fraction showed that the chromium in clay is immobile and stable. The toxicity characteristic leaching procedure (TCLP) test on clay fraction confirmed that the treated clay fraction is safe to dispose. The study showed that the proposed treatment technique is effective and economical for sediments with lower clay contents.     

剩余活性污泥的超声脱水及破解

文章从静态和动态研究了剩余活性污泥的超声脱水及污泥的破解。静态下,污泥的脱水应在低功率(以50W为例)短时间(7min)内进行,最高的脱水率(相对于未超声而言)可增加近16%;污泥破解应在高功率长时间下进行,本实验在250W的功率下连续处理20min,COD的增加值达到近1600mg/L;污泥的破解满足一级反应动力学。动态下,以低功率(50W)为例,脱水及破解曲线都比较平坦,污泥的总脱水率相对于未超声而言增加可达近23%;COD的增加值近似达1800mg/L。通过比较低功率下实验,动态实验效果明显优于静态实验。     

基于灰色关联分析激光熔覆Ni60A工艺参数优化

目的 针对激光熔覆Ni60A成形效率问题,研究工艺参数对单道熔覆效率和高宽比的影响规律,实现熔覆层工艺参数的预测与优化。方法 基于正交试验设计方法,采用信噪比对试验结果进行转换,并通过灰色关联分析多目标优化方法进行工艺参数优化。结果 最优工艺参数:激光功率为1900 W,扫描速度为8 mm/s,气流量为16 L/min,离焦量为9 mm。与正交试验最优结果相比,熔覆效率从24.195 mm³/s提高到24.278 mm³/s,高宽比从0.712降至0.654。结论 激光功率和离焦量对熔覆效率的影响最为显著,扫描速度和离焦量对高宽比的影响最为显著,验证试验结果与预测结果的误差仅为5.109%。利用灰色关联分析可实现激光熔覆多目标优化,为激光熔覆Ni60A成形效率工艺参数的预测和控制提供了理论依据。     

超声制备微乳化柴油的实验研究

微乳柴油是一种较佳的节能环保材料。采用聚氧乙烯失水山梨醇单油酸酯(Tween80)、失水山梨醇单油酸酯(Span80)和十二烷基苯磺酸钠复配成复配乳化剂,利用超声乳化机理,将超声波用于微乳化,研究了超声参数(声强,作用时间)、乳化剂及乙醇用量对乳液稳定性的影响,并通过正交实验找出了超声制备微乳化柴油的最佳工艺条件。该W/O乳液稳定时间随超声声强的增大而增加,且超声作用时间对乳液稳定时间有个最佳值。超声作用下乳化剂用量为2.5%(wt)时乳液最稳定。乙醇用量跟水油比有关,实验中水油比为0.1(V)时乙醇用量为5%(V),掺水量为10%(V)时的超声柴油微乳化最佳工艺条件为乳化剂用量为2.5%(wt),指示电流为3A(相当于声强为0.15 W/cm2),稳定剂用量为0.158%(wt),超声作用时间为15min,乙醇用量为5%(V)。     

Controlled growth of ZnO nanorods on common paper substrate and their application for flexible piezoelectric nanogenerators

A simple and effective method of synthesizing nanorods (NRs) and the ability to control the size and aspect ratio of them are crucial for fabricating nanodevices. In this paper, we present a systematic study of the growth of ZnO NRs on common paper substrates using a hydrothermal approach by adjusting the growth conditions. By a slight variation of the solution concentration and the growth time, significant changes in morphology and size (aspect ratio) of the obtained ZnO NRs have been controlled. Moreover, the piezoelectric power generation from ZnO-paper nanogenerators grown with different precursor concentration and growth time are also investigated. It is found that the morphology and aspect ratio of NRs have significant influence on the piezoelectric behavior. This type of flexible piezoelectric nanogenerator will have potential applications in implantable biosensors and wearable self-powered electronic devices.     

Ultrasound assisted destruction of estrogen hormones in aqueous solution: effect of power density, power intensity and reactor configuration

There are many reports documenting the adverse effects, such as feminization of fish, of estrogen hormones in the environment. One of the major sources of these compounds is from municipal wastewater effluents. The biological processes at municipal wastewater treatment plants cannot completely remove these compounds. This paper discusses the use of ultrasound to destroy estrogen compounds in water. The study examines the effect of ultrasound power density and power intensity on the destruction of various estrogen compounds which include: 17alpha-estradiol, 17beta-estradiol, estrone, estriol, equilin, 17alpha-dihydroequilin, 17alpha-ethinyl estradiol and norgestrel. These tests were conducted in single component batch and flow through reactors using 0.6, 2 and 4kW ultrasound sources. The sonolysis process produced 80-90% destruction of individual estrogens at initial concentration of 10microg/L within 40-60min of contact time. First order rate constants for the individual compounds under different conditions are presented. The estrogen degradation rates increase with increase in power intensity. However, the energy efficiency of the reactor was higher at lower power density. The 4kW ultrasound reactor was more energy efficient compared to the 0.6 and 2kW sonicators.     

双频复合超声强化无水葡萄糖溶液结晶成核研究

溶液结晶技术在许多领域有着广泛的应用,其中结晶成核是溶液结晶的关键环节。以无水α-葡萄糖为研究对象,采用双频复合超声(25 k Hz+40 k Hz)强化糖液结晶成核,研究了溶液浓度、超声功率和作用时间对成核速率的影响,对单频和双频作用的晶核形态进行了对比,并采用碘化钾溶液中碘的释放量研究超声空化产额。研究结果表明:在同等条件下,双频复合超声降低了溶液成核的初始浓度,提高了成核速率,同时得到粒度均匀的晶核;双频复合超声的空化产额远高于单频25 k Hz超声和单频40 k Hz超声的空化产额,双频复合超声具有协同作用。双频复合超声强化溶液成核是一种快速、高效、节能的方法。     

Study of inductively coupled Cl2/BCl3 plasma process for high etch rate selective etching of via-holes in GaAs

We have investigated the selective etching of 50 μm diameter via-holes for etch depth >200 μm using 30 μm thick photo resist mask in Inductively Coupled Plasma system with Cl₂/BCl₃ chemistry. Resultant etch rate/etch profiles are studied as a function of ICP process parameters and photo resist mask sidewall profile. Etch yield and aspect ratio variation with process pressure and substrate bias is also investigated at constant ICP power. The etch yield of ICP process increased with pressure due to reactant limited etch mechanism and reached a maximum of ∼19 for 200 μm depth at 50 mTorr pressure, 950 W coil power, 80 W substrate bias with an etch rate ∼4.9 μm/min. Final aspect ratio of etched holes is increased with pressure from 1.02 at 20 mTorr to 1.38 at 40 mTorr respectively for fixed etch time and then decreased to 1.24 at 50 mTorr pressure. The resultant final etch profile and undercut is found to have a strong dependence on the initial slope of photo resist mask sidewall angle and its selectivity in the pressure range of 20-50mTorr.