超声波法提取白藜芦醇工艺研究

目的优选超声波法提取虎杖中白藜芦醇的最佳工艺。方法本研究以虎杖中自藜芦醇提取率和吸光度值为考察指标,通过正交实验研究5个因素对提取率的影响。结果经过正交实验得到从虎杖中提取自藜芦醇的最佳工艺为：以80％的乙醇＋丙酮（体积比1：1）为提取剂,料液比1：10,pH=6,超声提取温度30℃,时间50min,平均分两次提取,提取率为1．83％。结论该实验确定的最佳提取工艺稳定性好且简便易行。     

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。     

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%.     

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。     

基于响应曲面法的桑叶萃余物多糖提取工艺优化

以提取生物碱和黄酮的桑叶萃余物为原料,采用响应曲面分析法(RSM)优化桑叶萃余物多糖的超声提取工艺。在单因素实验的基础上,选取对实验结果影响较大的因素:提取时间、提取温度、水料比,根据中心组合(BoxBenhnken)实验设计原理对桑叶多糖的超声提取工艺进行优化,苯酚-硫酸比色法测定桑叶多糖的含量。在分析各个因素的显著性和交互作用的基础上,得到最佳提取工艺条件为:提取温度79.29℃、超声波时间35.90min、水料比8.78mL/g。采用该工艺条件,桑叶多糖的提取得率达到2.97%。与模型预测值相符。     

枸杞色素的闪式提取和超声-微波协同提取工艺

目的 以枸杞为原料,比较不同提取工艺对枸杞色素吸光值的影响,以确定枸杞色素的最佳提取工艺.方法 通过单因素试验和响应面法对枸杞色素的闪式提取和超声-微波协同提取工艺进行研究.结果 闪式提取枸杞色素的最佳工艺条件为料液比(g/mL)1︰13,提取电压113 V,提取时间112 s,该条件下枸杞色素吸光度为0.457;超声-微波协同提取枸杞色素的最佳工艺条件为料液比(g/mL)1︰16,微波功率613 W,提取温度55℃,提取时间32 min,该条件下枸杞色素吸光度为0.502.结论 对2种提取方法在最佳工艺条件下进行比较,超声-微波协同提取法提取枸杞色素的效果优于闪式提取法.     

荸荠多糖的超声波辅助提取工艺

为提高荸荠多糖的得率,采用超声波辅助法提取荸荠多糖。通过单因素试验研究超声波功率、料液比、提取温度、超声处理时间、乙醇浓度对荸荠多糖得率的影响,确定荸荠多糖的最佳提取工艺。单因素试验结果表明,在本试验条件下,超声波功率为300W、料液比1：10、提取温度为50℃、超声时间25min时荸荠多糖得率最高。     

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。     

超声波-微波协同萃取沙棘籽油工艺优化

目的 研究采用超声波-微波协同法萃取沙棘籽油的工艺条件,及对沙棘籽油脂肪酸组成的影响。方法 选择溶剂种类、萃取时间、液料比、超声波功率、微波功率、萃取温度等6个因素进行单因素试验。在单因素试验的基础上,选择正己烷为萃取溶剂,以提取率为响应值,选择萃取时间、液料比、超声波功率、萃取温度等4个因素进行响应面优化试验。对此条件下得到的沙棘籽油和超临界CO2法萃取得到的沙棘籽油中的脂肪酸组成成分进行分析。结果 得到了超声波-微波协同法萃取沙棘籽油的最佳工艺条件,萃取时间为22 min,液料比值为9 mL/g,超声波功率为628 W,微波功率为200 W,萃取温度为57 ℃,在此条件下沙棘籽油的提取率可达13.97%。超声波-微波协同法萃取得到的沙棘籽油,其不饱和脂肪酸质量分数高达88.93%,最高的为亚油酸（39.60%）,其次为亚麻酸（32.60%）。结论 超声波-微波协同萃取法是一种提取沙棘籽油的有效方法。     

超声波破碎发酵性丝孢酵母提取蛋白酶条件的研究

发酵性丝孢酵母(Trichosporon fermentans)所产蛋白酶为胞内酶,要提取蛋白酶需对细胞进行破碎。利用超声波破碎发酵性丝孢酵母细胞,研究超声波工作条件对提取蛋白酶活性的影响。通过单因素试验和正交试验,确定提取蛋白酶的适宜条件为输出功率550 W、工作总时间13 min、超声波每次辐射时间7 s(间歇时间5 s)、每克细胞缓冲液加入量20 m L,在此条件下提取的蛋白酶活力达到393.78 U·g-1。     

加筋圆柱壳声辐射特性研究及声学优化设计

为研究全频段加筋圆柱壳声辐射特性,基于VA-ONE建立FE-BEM混合法、FE-SEA混合法及SEA法低中高全频段的计算模型,并进行加筋圆柱壳辐射声功率的计算,从结构固有模态角度研究了各阶模态的声辐射效率。结果表明,加筋能够减小圆柱壳结构的总体辐射声功率,尤其可以减小低频段的辐射声功率;在中低频区,各阶模态的模态辐射效率具有较大差异,在中高频区,则相差不大。进一步研究了激励位置、壳厚、材质及辐射介质对加筋圆柱壳声辐射特性的影响。为减小加筋圆柱壳对外场点的辐射声功率,基于NCT模块及Design Optimization模块进行声学优化设计,结果表明,将GA算法与SQP算法或MMA算法组合使用不仅可以减少运算时间,而且可以获得较好的优化方案。     

Dynamics of sublimation and initial erosion plasma formation under the action of quasicontinuous laser radiation on metals

Onset times of sublimation and plasma production as well as of pressure on surfaces under the action of quasicontinuous Nd-laser radiation with a power density up to 10 MW/cm² on metals are investigated experimentally. The results on sublimation onset time and dynamics are compared with a thermophysical action model that accounts for phase boundaries of melting and sublimation as well as for the temperature dependence of thermophysical characteristics of metals and the time dependence of the power density of laser radiation.The main results were presented at the 7th All-Union Conference on Interaction of Optical Radiation with Matter [1].Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 4, pp. 448–452, April, 1994.     

A new method of semi-continuous casting of AZ80 Mg alloy billets by a combination of electromagnetic and ultrasonic fields

The influence of low frequency electromagnetic field and power ultrasonic field on the microstructure of AZ80 Mg alloy billets was studied. The magnetic flux density and time average electromagnetic volume force density were obtained by numerical simulation. The acoustic pressure distribution was also numerically calculated in order to characterize the ultrasonic field propagation. After comparison of the different effects of grain refinement by low frequency electromagnetic casting (LFEC) and ultrasonic casting (UC), a new method (LFEC + UC) was developed by simultaneously applying ultrasonic vibration to the melt during low frequency electromagnetic semi-continuous casting of AZ80 Mg alloy billets. With the application of the compound field under the optimum conditions, the as-cast macrostructure and microstructure were refined and homogeneously distributed. An obvious improvement of mechanical properties was finally obtained. The mechanisms of grain refinement and interaction of low frequency electromagnetic field and power ultrasonic field with the melt were discussed.     

Effect of UV radiation on slow relaxation processes in ferroelectric thin-film capacitors

The influence of UV radiation with wavelengths of about λ = 340 nm and power within 0.001–0.15 mW on the suppression of slow relaxation of residual polarization in ferroelectric capacitors based on thin (Ba,Sr)TiO₃ (BSTO) films in a paraelectric state has been studied. Experimental data on the behavior of capacitance relaxation time and conduction current in ferroelectric capacitors under the action of UV radiation are presented. A mechanism of relaxation with a characteristic time on the order of 1 s is found that is not affected by UV radiation.     

结构噪声主动控制在时域声辐射模态下的仿真研究

以简支矩形板为例，提出了利用时域声辐射模态进行声辐射研究。研究表明时域声辐射模态既与时间无关，且互相独立，使得计算和控制声功率得以简化。针对瞬时声功率主要由第一阶辐射模态的声功率所决定的特点，在时域里进行结构噪声的主动控制研究，通过抵消第一阶辐射模态的声功率使得总的声功率得以有效降低。在此基础上，建立了时域声辐射模态的状态空间方程，对该方程的性能进行了分析，并利用最优控制算法的自适应反馈控制系统进行仿真计算。最后讨论了不同情况下的计算精度，并对影响仿真结果的因素进行了分析。     

超声清洗法回收冷轧厂磁过滤物中的纳米铁粉

研究一种冷轧厂磁过滤物中纳米铁粉的回收方法,采用超声清洗法除去铁粉表面的油污,得到纯净的纳米铁粉,通过试验研究超声频率、功率密度、清洗温度对除油效果的影响,采用X射线衍射和扫描电子显微镜对铁粉产品进行表征。结果表明,相对于机械搅拌清洗,采用超声清洗含油铁粉,可提高清洗液的除油能力;超声频率为40 kHz,功率密度为0.44 W/cm2,清洗温度为40℃时,用清洗液清洗4次,每次清洗时间为20 min,用去离子水漂洗至澄清,真空干燥5 h,所得纳米铁粉中铁元素的质量分数为95.75%。     

辐射力天平法测量相控阵超声换能器的声功率

超声换能器相控阵已用于聚焦超声治疗的研究和应用已有20多年历史,但其声功率P的测量仍缺乏方便有效简易的测量方法。文章旨在提出一种基于凸球面吸收靶的辐射力天平（Radiation Force Balance,RFB）方法,测量其声功率。理论推导了这种RFB在各种阵元组合下的比值r=P/cF（c为水中声速,F为阵的声束轴方向的总辐射力）。论述了测量各种组合的发射声功率的实施方法和测量程序。为实际的测量系统设计和应用建立了良好的工作基础。     

Room-temperature ultrasonic annealing of radiation defects in silicon

Room-temperature ultrasonic annealing of point radiation defects in the bulk of silicon is demonstrated for the first time. The radiation defects in single crystal silicon were generated by the exposure to γ radiation from a ⁶⁰Co source. A qualitative model of processes in the system of radiation defects under the action of ultrasound is proposed.     

The combined effect of melt stirring and ultrasonic agitation on the degassing efficiency of AlSi9Cu3 alloy

The combined effect of high intensity ultrasound and melt stirring on the degassing of AlSi₉Cu₃ using simultaneously the novel MMM (Multi-frequency Multimode Modulated) ultrasonic technology to promote cavitation, and low frequency mechanical vibration to induce melt stirring, was studied. On a first stage single low frequency mechanical vibration experiments were carried out in water in order to visualize and characterize its individual effect on the liquid dynamics. On a second stage ultrasonic vibration combined with different mechanical vibration frequencies, melt temperatures and processing times were tested in liquid AlSi₉Cu₃ alloy and their influence on the degassing efficiency was evaluated and compared with the results of the single MMM ultrasonic degassing technique. Fixed ultrasonic parameters (frequency and electric power) were used, according to the best results obtained in former experimental works developed by the authors. For the experimental conditions used in this research, it was found that melt stirring significantly improves degassing efficiency, and such improvement depends on the metal temperature and the mechanical vibration frequency. The experimental results suggest that combining melt agitation and ultrasonic vibration it is possible to achieve almost the aluminum alloy theoretical density without increasing the processing time.     

A CuBr laser with high efficiency in the double-pumping-pulse mode

The results of examination of characteristics of a CuBr laser operated in the double-pumping-pulse mode with a lasing pulse repetition rate of 50 Hz are presented. The potential to enhance the laser efficiency by choosing the optimum voltages of dissociation and excitation pulses and time delay values is discussed. It is confirmed that a more than twofold increase in the laser efficiency may be achieved through optimization and matched injection of the excitation-pulse energy into the active medium plasma. A laser efficiency as high as 2.6% (with respect to an excitation pulse) with an average power of 16 mW, an energy of 0.32 mJ, a halfamplitude laser pulse duration of 40 ns, and a time delay of 150 μs is demonstrated. The maximum average radiation power is 37 mW with an energy of 0.7 mJ and a laser efficiency of 0.7% at an energy density of 24 (2.7) mJ/cm³ of a dissociation (excitation) pumping pulse.