超声波技术在火山碎屑物发育土壤粒度分析中的应用

利用40kHz超声波清洗机,设计不同的超声功率和超声时间,对火山碎屑物发育土壤进行分散处理;再用湿筛-吸管法测定土壤颗粒含量,对测定结果进行分析。研究表明:增大超声功率能促进土壤颗粒的分散,但80w和140w超声功率引起的土壤各粒级含量变化不大,均小于3.00%;延长超声时间对火山碎屑物土壤分散效果影响显著,对于粗颗粒为主的样品各粒级含量变化均很小,对于细颗粒为主的火山碎屑物土壤样品,以粉粒和黏粒含量变化更大;建议火山碎屑物发育土壤的颗粒分散采用(NaPO_3)_6-超声波联合分散法,超声条件设定为:频率40kHz,功率140w,震荡时间25min。     

超声辅助萃取芒果叶中芒果苷提取条件优化

为优化芒果叶中芒果苷的提取条件,以溶剂用量、超声时间、超声温度和超声功率为考察因素,采用单因素试验和正交试验对提取条件进行优化;在优选出的超声萃取条件下测定了6个品种芒果叶中芒果苷的含量,并与常规浸渍提取法进行对比。结果表明,超声波辅助提取芒果叶中芒果苷时,影响提取效果大小的顺序依次为溶剂用量超声温度超声功率超声时间;用超声波辅助提取芒果苷的最优组合为:样品量1.0 g,乙醇用量20 mL,超声时间40 min,超声温度50 ℃,超声功率160 W;超声萃取法不但缩短了提取时间,还提高了提取效率,与浸渍提取法相比,超声萃取提取芒果苷量增加了21.60%～26.69%。     

超声波辅助提取紫丁香叶叶绿素的工艺

以深秋的紫丁香树叶为原料,利用超声波辅助提取其中的叶绿素。首先研究了4种不同溶剂对提取的影响,然后在单因子试验基础上,探讨了料液比、超声波功率、超声波处理时间和超声提取次数4个因素对叶绿素提取的影响,用正交试验法优化了超声波辅助提取叶绿素的条件。最后将超声波法与传统提取法进行了对比。结果表明,紫丁香树叶中叶绿素a和叶绿素b的含量分别为0.37%和0.15%,叶绿素的总含量为0.52%;以乙醇∶丙酮为1∶2之混合溶剂的提取效果最好;优化的叶绿素超声波辅助提取条件为:料液比1∶7.5,超声波功率400W,提取3次,每次处理时间20min,提取率能达到(91.85±0.8)%。室温条件下,超声波辅助提取的提取率高于传统提取法17.13个百分点。     

响应面法优化超声波辅助灵芝黑色素提取工艺

为探究超声波辅助法提取灵芝天然黑色素的最佳工艺条件,本试验以灵芝子实体粉为原材料,以黑色素溶液吸光度为响应值,分别考察Na OH浓度、料液比、超声时间和超声功率4个因素对提取效果的影响,并在单因素试验基础上,通过Box-Behnken响应面分析法优化灵芝天然黑色素的超声波辅助提取工艺。结果表明,响应面法合理可行,最佳提取条件为Na OH浓度1 mol·L~(-1)、料液比1∶39.7g·m L~(-1)、超声功率为162 W和超声时间49.8 min,在此条件下灵芝黑色素吸光度为0.782,与预测值0.783相近。本试验从多角度优化超声波辅助提取灵芝黑色素工艺,为灵芝黑色素的进一步加工提供了理论依据。     

超声波辅助高氯酸法提取牛肝中左旋肉碱工艺优化

为探索超声波处理对左旋肉碱提取效果的影响,找出最佳的处理技术参数,以牛肝脏为原料,用超声波辅助酸提法提取左旋肉碱,在超声功率、超声时间和料液比3个单因素试验的基础上,采用二次回归通用旋转组合试验设计对左旋肉碱超声波辅助提取工艺进行优化。结果表明,试验中所选参试因子对左旋肉碱提取得率的影响大小顺序为超声波功率、料液比、超声时间。最优工艺条件为:原料用量为100g,在超声功率437W,超声时间15min,料液比1∶5g/mL时,左旋肉碱提取得率达38.37mg/kg。该研究表明超声波技术在左旋肉碱提取工艺中具有较高的应用价值和指导作用。     

土壤颗粒分级过程中超声破碎和离心分离的条件选择

按照离心机SORVALL Legend RT的水平转子的尺寸,并根据斯托克斯公式对文献中已有的土壤颗粒分级方法中的离心时间重新设定。同时讨论了利用超声波进行土壤颗粒分散的使用条件,尤其应针对不同的土壤调整超声破碎仪的能量输入。用新优化的土壤颗粒分级方法对中国科学院沈阳生态试验站采集的棕壤进行了分级,其结果与吸管法所得结果基本一致,并且回收率能达到95%以上。     

超声预处理对半干型荔枝干干燥时间的影响

为探讨半干型荔枝干在干燥前用超声波预处理对其干燥时间的影响,在单因素试验获得效果的基础上,进一步利用响应曲面分析法对超声波预处理条件进行优化,建立了数学回归模型;并对相关机理进行了初步探讨。结果表明：干燥前的超声波预处理能够缩短其干燥时间;预处理的优化条件为：超声频率40 kHz,超声时间32.6 min,超声功率 354 W;在优化条件下预处理后,荔枝干燥至其果肉湿基含水率约为32%时的预测干燥时间为15.65 h,而未处理荔枝所用时间需26.80 h;验证试验实测时间为15.93 h,表明数学回归模型所得的预测值与实测值有较好的一致性;电镜扫描结果表明超声预处理对荔枝内外果皮结构有明显影响,此结果可较好地解释超声预处理能够缩短荔枝干燥时间的机理。     

前处理方法对激光粒度仪测试碳酸盐岩红土粒度结果的影响

前处理方法的优化研究是促进激光粒度仪分析技术在南方红土区推广的关键环节。以黄土粒度前处理方法为基础,设定不同的H2O2、HCl和分散剂(Na PO3)6的加入剂量以及不同的反应温度和超声波震荡时间来处理采自云南高原程海地区海拔2000 m的碳酸盐岩红土样品,结果发现:(1)加入HCl处理会使激光粒度仪测量结果偏粗,不加HCl只加H2O2可以获得较细的粒度测量结果;(2)加(Na PO3)6分散剂后样品测试结果重现性较高,但粒度偏粗,当加入剂量超过5 ml(0.05 mol l-1)后加入剂量的多少对测试结果影响不大,未加(Na PO3)6的样品测试结果重现性差,但粒度总体偏细;(3)加热处理比未加热处理样品的粒度偏粗,加热不利于样品的分散;(4)经超声波震荡的样品较未震荡的样品颗粒分散程度高,但震荡时间超过2分钟后,增加震荡时间对分散结果影响不大。     

热辅助超声波处理对猕猴桃浊汁的杀菌效果及品质影响研究

针对热杀菌猕猴桃浊汁中营养成分损失严重的问题,本试验对不同热辅助超声波处理工艺参数对猕猴桃浊汁理化特性的影响及杀菌效果进行研究,并优化最佳工艺参数。以猕猴桃浊汁为样品,选取猕猴桃浊汁的理化指标及杀菌率为响应值,以超声功率、超声时间、温度为因素,进行响应面试验,在筛选猕猴桃浊汁理化特征指标的基础上,建立杀菌率及猕猴桃浊汁理化特征指标模型并优化得出最佳工艺参数。结果表明,猕猴桃浊汁的理化特征指标为叶绿素保存率、PPO活性、△E值、糖酸比;最佳工艺参数为:超声功率420 W、超声时间30 min、温度60℃,在此条件下,猕猴桃浊汁的叶绿素保存率为30.99%、PPO活性为19.48 U·mL^-1、△E值为4.43、糖酸比为6.17、杀菌率为95.68%。本研究为热辅助超声波技术应用于猕猴桃浊汁的加工提供了理论依据和技术指导。     

超声波对鱿鱼墨黑色素成分和物理结构的影响

为了提高鱿鱼综合利用价值,以加工废弃物中的鱿鱼墨黑色素为原料,研究超声波处理对黑色素成分和物理结构的影响。采用超声功率15 W/mL、超声时间2 s、间歇时间1 s、总工作时间20 min的工作条件对黑色素进行处理。结果表明：鱿鱼墨黑色素在超声波处理后,波长为224 nm和267 nm附近的两个峰吸光值显著增加,黑色素在环己烷中的溶解性显著增加,样品中没有新的具有紫外可见吸收特性物质生成;黑色素中蛋白质在超声波处理后的没有发生显著变化,而脂质含量显著减少;超声波后Ca、Mg、Na、K、Fe、Cu、Cd和Pb等8种金属元素含量均显著降低;电镜图片显示黑色素微球颗粒在超声过程中发生了爆炸,产生更为细小的碎片和碎末。     

Simplification of the standard method for determination of non-exchangeable NH4−N in soil

The widely-used Silva-Bremner method for determining non- exchangeable NH₄?N in the soil was modified so as to reduce reagent requirement and the time taken to carry out the analyses. In the modification, boiling the mixture of soil and KOBr on a hot plate was replaced with heating the soil/KOBr mixture, directly placed in centrifuge tubes, in a boiling water bath or a microwave oven. The best procedure is to keep the soil/KOBr mixture for 10 minutes in the water bath or for 10 minutes at 50% of full power in a microwave oven. The modified method gave similar values to the standard method on 4 quite different soils and also slightly increased reproducibility.     

Effect of ultrasonic power on soil organic carbon fractions

Ultrasonic dispersion is a prevalent tool for soil fractionation. It is widely ignored that variation in ultrasonic power might lead to significantly different dispersion. We evaluated the effect of power variation with constant energy on the fine fraction mass, its organic C content and quality. All parameters increased significantly with power. The term “stable aggregates” as used in fractionation schemes cannot be defined by ultrasonic energy alone but power needs to be standardized, too.     

基于局部均值分解的触电故障信号瞬时参数提取

针对如何快速、准确地提取生物体触电故障暂态信号中的电力参数问题,提出了一种基于局部均值分解（local mean decomposition, LMD）的生物体触电时总泄漏电流信号瞬时参数提取方法,该方法首先利用局部均值分解将生物体触电时的总泄漏电流信号分解为一组乘积函数分量之和,每个乘积函数（product function, PF）分量可以表示为一个调幅信号和一个调频信号的乘积,然后由调幅信号和调频信号分别计算得到信号的瞬时幅值和瞬时频率。与采用希尔伯特黄变换方法相比,LMD具有瞬时频率曲线波动小和瞬时幅值函数端部失真小等优点。仿真信号分析结果表明：对测试信号进行LMD和经验模态分解（empirical mode decomposition, EMD）分解分别得到3个PF分量和5个IMF（intrinsic mode function）分量,分解前后信号的能量变化值分别为0.2851、0.5633,且LMD比EMD所需分解时间短0.0743s,与Hilbert变换相比,该文方法计算的瞬时幅值和瞬时频率更为平滑,在一定程度上避免了Hilbert 变换计算过程中的负频率和端点效应现象。试验信号分析结果表明：对消噪后的总泄漏电流信号进行LMD和EMD分解,分别得到5和6个分量,分解前后信号的能量变化值各为0.5574、0.8896,所用分解时间分别为0.0835、0.2479 s;在求取瞬时频率方面,LMD方法求取的主导分量瞬时频率可判定生物体触电时刻,而经Hilbert变换求取的瞬时频率不仅无法判定生物体触电时刻,还出现了负的频率值,无法解释其物理意义;在求取瞬时幅值方面,该文方法与Hilbert变换求取的触电前总泄漏电流信号的瞬时幅值的平均值分别为11.3240、12.3728 mA,与原生物体无触电时总泄漏电流的幅值11.3538 mA的绝对误差分别为0.0298、1.0190 mA,另外,2种方法求取的生物体触电后总泄漏电流信号的瞬时幅值与原生物体触电后总泄漏电流的幅值的绝对误差分别为0.4340、0.6643 mA。因此,仿真信号和试验信号分析结果均证明所提方法是有效和可行的。     

酸性土壤水溶性氟浸提方法的研究

本文比较研究了振荡、超声、沸水浴和烘箱4种浸提酸性土壤水溶性氟的方法,然后采用离子色谱法对浸提液进行测定,并通过对测定数据进行统计与方差分析来确定最佳浸提方式。结果显示,水土比5:1,浸提时间20 min、温度60℃是振荡法与超声法浸提酸性土壤水溶性氟含量的最佳条件。在此条件下,振荡法与超声法浸提的土壤水溶性氟含量无显著差异,标准偏差均小于0.3%。超声法浸提的酸性土壤水溶性氟含量显著高于各自最佳处理条件下的沸水浴法与烘箱法浸提的水溶性氟含量。在离子色谱测定水溶性氟过程中,质量控制样品均在1倍标准偏差范围内。因此,采用离子色谱法测定超声法或振荡法浸提的酸性土壤水溶性氟是一种可行的、准确的试验方法,特别对于批量土壤样品的测定具有重要意义。     

超声辅助竹节虾头酶解及抗氧化肽分离研究

为了实现竹节虾加工副产物的高值化利用,以竹节虾加工废弃物中的虾头副产物为原料,以水解度和DPPH清除率作为评价指标,采用中性蛋白酶酶解,通过响应面法优化超声辅助酶解工艺,并依次通过超滤、凝胶层析色谱和反相高效液相色谱等分离方法,从竹节虾虾头酶解产物中分离制备抗氧化肽,采用超高压液相色谱串联质谱联用技术对肽的结构进行表征。结果表明,在中性蛋白酶添加量为3 000 U·g~(-1)、p H值7.0条件下,最佳超声辅助酶解工艺参数为超声时间41 min,超声温度55℃,超声频率22 k Hz,料液比1∶9(w/v),在此条件下获得的酶解产物DPPH清除率达69.50%。当水解时间为0.5~2.5 h时,超声辅助酶解的酶解产物水解度和DPPH清除率比非超声辅助酶解工艺分别高17.95%和18.83%,该工艺缩短了酶解时间,节约了能耗。酶解产物经超滤初步分离发现,相对分子质量在3k Da(SHP4)的组分具有显著的抗氧化活性。用凝胶层析法进一步分离纯化SHP4组分后得到4个峰,其中SHP4-II的DPPH清除率最高;SHP4-II通过反相高效液相纯化后也得到4个主要肽峰,在多肽含量为1.5 mg·m L~(-1)时,SHP4-II-4的DPPH清除率最高,达到85.69%,并且具有较好的分离度,质谱分析发现,该抗氧化肽的结构为Gly-Asn-Gly-Leu-Pro(455.99 Da)。本研究结果为虾肽抗氧化保健食品的研发提供了一定的科学依据。     

Redistribution of particulate organic matter during ultrasonic dispersion of highly weathered soils

The use of ultrasonic energy for the dispersion of aggregates in studies of soil organic matter (SOM) fractionation entails a risk of redistribution of particulate organic matter (POM) to smaller particle‐size fractions. As the mechanical strength of straw also decreases with increasing state of decomposition, it can be expected that not all POM will be redistributed to the same extent during such dispersion. Therefore, we studied the redistribution of POM during ultrasonic dispersion and fractionation as a function of (i) dispersion energy applied and (ii) its state of decomposition. Three soils were dispersed at different ultrasonic energies (750, 1500 and 2250 J g^?1 soil) or with sodium carbonate and were fractionated by particle size. Fraction yields were compared with those obtained with a standard particle‐size analysis. Undecomposed or incubated (for 2, 4 or 6 months) ¹³C‐enriched wheat straw was added to the POM fraction (0.25–2 mm) of one of the soils before dispersion and fractionation. Dispersion with sodium carbonate resulted in the weakest dispersion and affected the chemical properties of the fractions obtained through its high pH and the introduction of carbonate. The mildest ultrasonic dispersion treatment (750 J g^?1) did not result in adequate soil dispersion as too much clay was still recovered in the larger fractions. Ultrasonic dispersion at 1500 J g^?1 soil obtained a nearly complete dispersion down to the clay level (0.002 mm), and it did not have a significant effect on the total amount of carbon and nitrogen in the POM fractions. The 2250 J g^?1 treatment was too destructive for the POM fractions since it redistributed up to 31 and 37%, respectively, of the total amount of carbon and nitrogen in these POM fractions to smaller particle‐size fractions. The amount of ¹³C‐enriched wheat straw that was redistributed to smaller particle‐size fractions during ultrasonic dispersion at 1500 J g^?1 increased with increasing incubation time of this straw. Straw particles incubated for 6 months were completely transferred to smaller particle‐size fractions. Therefore, ultrasonic dispersion resulted in fractionation of POM, leaving only the less decomposed particles in this fraction. The amounts of carbon and nitrogen transferred to the silt and clay fractions were, however, negligible compared with the total amounts of carbon and nitrogen in these fractions. It is concluded that ultrasonic dispersion seriously affects the amount and properties of POM fractions. However, it is still considered as an acceptable and appropriate method for the isolation and study of SOM associated with silt and clay fractions.     

Preparation and Structure Characterization of Carboxymethyl Corn Starch Under Ultrasonic Irradiation

To discover new synthesis technology and increase the degree of substitution (DS) of carboxymethyl starch (CMS), ultrasound‐modified CMS (U‐CMS) was successfully prepared under ultrasonic irradiation in the alkali condition with corn starch (CS) as the raw material, ethyl alcohol as the solvent, and monochloroacetic acid as the carboxymethylated reagent. The effects of ultrasound conditions (ultrasonic action sequence, ultrasonic radiation time, and ultrasonic power) and etherification time after ultrasonic irradiation on DS of U‐CMS were studied separately through single‐factor experiments. Meanwhile, the granule morphology, crystal type, and molecular structure of U‐CMS were studied by scanning electron microscopy (SEM), X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT‐IR). The results showed that DS of U‐CMS prepared under certain conditions (ultrasonic radiation time before alkalization, 40 min; ultrasonic radiation temperature, 35°C; ultrasonic power, 170 W; and etherification time, 180 min) improved 38.7% compared with that without ultrasonic radiation. The SEM, XRD, and FT‐IR results illustrated that crystal‐type change of the starch granule after ultrasonic irradiation was not obvious. However, the number of sunken points and holes on the granule surface increased, so that the specific surface expanded, which improved the carboxymethylation.     

基于局部均值分解（LMD）的单通道触电信号盲源分离算法

针对从低压电网的剩余电流中提取触电电流的难题,该文提出局部均值分解(local mean decomposition,LMD)与盲源分离相结合提取触电电流的方法。利用LMD算法自适应的将剩余电流信号分解为若干个PF(product function)分量,计算各分量与原始信号的相似系数,选取相似系数最大且大于0.8的模态分量构造虚拟通道,与剩余电流信号一起构建盲源分离的2个通道,再利用FastICA算法从剩余电流信号中提取触电电流。试验结果表明:相较于经验模态分解(empirical mode decomposition,EMD)时间0.129 s,LMD分解时间为0.032 s,速度更快;在单相电路触电时,基于LMD-FastICA算法和EMD-FastICA算法提取的触电电流与原始触电电流的平均相关系数分别为0.937 4和0.925 3,平均相对误差分别为0.096 2和0.109 8;在三相电路触电时,基于LMD-FastICA算法和EMD-FastICA算法提取的触电电流与原始触电电流的平均相关系数分别为0.962 4和0.948 9,平均相对误差分别为0.056 4和0.081 55;LMD-FastICA与EMD-FastICA两种算法分解信号的峰值因子的相对误差范围分别为0.001～0.103和0.012～0.155,且抑制端点效应更好。研究结果可为开发基于触电电流动作的新型剩余电流保护装置奠定理论基础。     

超声波辅助提取杠柳脂溶性成分工艺优化

为了优化超声波辅助提取杠柳脂溶性成分的工艺,该文在单因素试验基础上,选取超声波功率、提取时间、液料比为主要影响因素,分析了3个主要影响因素对杠柳脂溶性成分提取结果的影响,应用响应面分析法优化了超声波辅助提取杠柳脂溶性成分的工艺方法,并使用GC-MS联用仪检测了杠柳脂溶性提取物的主要成分。结果表明:超声波辅助提取杠柳营养体脂溶性成分的最佳工艺为:在室温(20℃)及超声波频率20kHz条件下,提取试剂为石油醚,超声波辅助提取时间为70min,超声波功率为730W,料液比为1∶10g/mL。该工艺条件下,杠柳脂溶性成分的实际提取得率可达到6.14%。