不同澄清剂对五味子水提物澄清效果的比较

以680nm处的透光率作为澄清度的指标,比较明胶、淀粉、蛋清和壳聚糖4种澄清剂在不同浓度、温度、处理时间下的澄清效果。结果表明:明胶和壳聚糖澄清效果较好,蛋清次之,而淀粉几乎无澄清作用。0.16%的明胶和0.08%的壳聚糖澄清效果最佳,透光率分别为84.02%和84.44%。蛋清的澄清速度较明胶和壳聚糖慢;温度对蛋清和壳聚糖几乎无影响,但明胶随处理温度升高透光率下降。     

中药黄芩中神经氨酸酶抑制剂的超滤质谱筛选研究

采用超滤质谱分析技术, 结合体外酶活性实验方法, 从传统中药黄芩提取物中筛选神经氨酸酶抑制剂. 研究结果表明, 中药黄芩提取物具有较强的神经氨酸酶抑制活性, 利用超滤质谱方法从中筛选并鉴定出了六种具有潜在神经氨酸酶抑制活性的化合物, 为开发神经氨酸酶抑制剂提供了实验依据.     

复配絮凝剂对荷叶水提液的絮凝工艺研究

为了克服传统中药提取工艺中有效成分损失率高的缺点,提高药液的澄清度和药效,优化生产工艺,采用絮凝法对中药水提液进行除杂,并在实验中将絮凝剂壳聚糖与单宁复合使用,以水提液的絮凝率和黄酮损失率为衡量指标.通过正交实验,得出最优操作条件为壳聚糖投加量为1.071 g·L-1,单宁投加量为5.3579 g·L-1,温度为30℃,搅拌转数为60 r·min-1.在此基础上研究了各个因素随絮凝工艺条件的变化趋势及对絮凝效果的影响.实验结果表明,用复配絮凝剂处理荷叶水提液能够有效去除杂质,降低黄酮损失率,缩短生产周期.     

重金属铅离子胁迫下玉米叶片光谱弱差信息的DSAT甄别模型

光谱间微弱信息测度是当今高光谱遥感研究难点之一,传统光谱测度方法难以区分光谱信息的微弱差异。研究设计了不同浓度的铅(Pb)污染实验,并测量了不同浓度铅离子(Pb2+)胁迫下玉米叶片的高光谱反射率、叶绿素含量及Pb2+含量,但是从所测结果得出,不同浓度Pb2+胁迫下的光谱相似性相关系数均达到0.999,难以区分不同浓度Pb2+胁迫引发的光谱间微弱信息差异和污染程度。针对这一情况,基于光谱微分处理、正切函数增强、光谱角量度与波谱分段检测等,提出了一种新型的相似光谱测度方法,即微分光谱角正切(derivative spectral angle tangent,DSAT)法。为了验证DSAT在区分相关系数达0.99以上相似光谱的可行性和有效性,将DSAT用于不同浓度Pb2+胁迫玉米叶片的整体波形与光谱区间子波形的信息差异性度量与检测。实验结果得到,波形差异信息与玉米叶片中叶绿素相对浓度与Pb2+含量显著相关。进而也证明DSAT法在甄别较高相似性光谱间差异上具有更好的实用性和优越性。     

热处理竹材的化学成分傅里叶变换红外光谱分析

化学热处理是实现可再生木质生物能源中纤维素高效利用及半纤维素糖化转换的关键步骤。通过预处理过程可以快速去除难溶木质素,实现细胞壁中半纤维素的物理化分离,使得植物细胞壁中化学成分发生变化,从而增加木质纤维素的产出量。以硫酸(H₂SO₄)、稀碱(NaOH)及甘油(glycerol)为预处理介质,采用不同的热处理温度(硫酸(H₂SO₄)、稀碱(NaOH)热处理温度为117和135 ℃;甘油(glycerol)热处理温度为117 ℃)),对竹材处理前后的主要化学组分进行对比分析,并通过傅里叶变换红外光谱进一步证实化学热处理前后竹材化学组分的变化,以获得不同的化学热处理介入下竹材化学成分转换的主要变化规律和机理。结果表明：热化学处理后竹材的纤维素产出量明显增加。纤维素得率及木质素的去除率在不同的处理介质条件下的变化规律为,稀碱(NaOH)处理效果优于稀酸(H₂SO₄)和甘油(glycerol);此外,在相同介质条件下135 ℃热处理效果比117 ℃热处理效果显著。对于不同处理条件的半纤维素的降解程度大小变化结果与此相同。通过红外光谱分析可知,热处理后纤维素环状C-O-C不对称伸缩振动峰出现峰值分解,半纤维素的红外吸收特征峰出现明显陡降变化,木质素苯环特征吸收峰明显减弱,证明纤维素产出量明显增加,半纤维素降解趋势明显,木质素去除效果良好。傅里叶红外变换光谱分析结果与标准测定结果一致。     

叶片多角度偏振光谱特性影响因素的实验研究

通过测量绿萝、银杏、苹果三种叶片的多角度偏振光谱,采用斯托克斯矢量法计算了叶片的多角度光谱偏振度,并通过PROSPECT模型反演得到叶片的叶绿素、水分含量,进而分析了叶绿素、水分含量对叶片多角度光谱偏振度的影响,探索了观测几何条件与不同波段叶片偏振度间的关系。结果表明,相对于近红外波段,红光波段的偏振度受叶绿素含量变化的影响较小,而水分含量对这两个波段的偏振度基本均无明显影响。在反映叶片偏振度随观测几何变化方面,近红外波段较另外两个波段有着更好的敏感性和稳定性,但其偏振度值较另外两个波段偏小。     

Ultrasound-assisted extraction of functional compound from mulberry (Morus alba L.) leaf using response surface methodology and effect of microencapsulation by spray drying on quality of optimized extract

This study aimed to optimize the ultrasound-assisted extraction (UAE) condition of mulberry leaf extract (MLE) using response surface methodology and to microencapsulate MLE by spray drying using different coating materials and ratios of coating material and MLE. The extraction results showed that MLE from condition of 60 °C (X₁, temperature), 30 min (X₂, time) and 60% v/v (X₃, ethanol concentration) exhibited the highest bioactive compound and antioxidant activity (DPPH and FRAP assay). Based on this optimal condition, MLE was further encapsulated by spray drying. It was found that MLE encapsulated with resistant maltodextrin at ratio of MLE and resistant maltodextrin 1:1 (w/w) showed the highest encapsulation yield (%) and encapsulation efficiency (%). Water solubility, moisture content and water activity were non-significant (p > 0.05) among the microcapsules. The scanning electron microscope (SEM) revealed that the types of coating material affected their microstructures and microcapsules prepared by resistant maltodextrin as coating material had a spherical shape, smooth surface and less shrinkage than microcapsules prepared by maltodextrin and gum arabic which had rough surfaces. The highest antioxidant activity was obtained from microcapsule prepared by gum arabic at ratio of MLE and gam arabic 1:2 (w/w). In conclusion, optimal condition from UAE and encapsulation by spray drying suggest the critical potential for production of functional food with improved bioactive compound stability and maximized antioxidant activity.     

Processing tactics for low-cost production of pure nuciferine from lotus leaf

Nuciferine is an important drug candidate for the treatment of many diseases. However, there is no general method for its low - cost production. In this work, a feasible method for the production of nuciferine from lotus leaf, using ultrasonic-assisted extraction-solid phase extraction (UAE-SPE) as extraction and cleanup procedure, was developed. Petroleum ether and silica gel have been successfully used as extraction solvent and adsorbent to integrate UAE with SPE, respectively. Except for filtration, no treatment (e.g. concentration and redissolution, etc) was needed on UAE extract before SPE and the effluents obtained in the loading process of SPE could be used as UAE extraction solvent without purification. No obvious decline in the extraction efficiency of UAE and adsorption capacity of SPE was observed at least for 5 runs, which provides a feasible way for the continuous production of nuciferine in industry, i.e. Cyclic UAE-SPE. Moreover, SPE column could be conveniently regenerated and reused without significant decline in its adsorption capacity at least for 5 cycles, which can be used to reduce the cost of the whole system further. In comparison with other cleanup procedures, Cyclic UAE-SPE showed apparent advantages in energy conservation and emission reduction. LLE and crystallization were applied to separate nuciferine from other impurities further. Under optimum conditions, the total recovery rate of nuciferine with a purity over 90.0% from lotus leaf reached 50.1%. All in all, the developed method has advantages in convenient operation, low cost, and high efficiency, thus, is fitting for the production of high purity nuciferine.     

Surface-enhanced fluorescence and application study based on Ag-wheat leaves

Wheat leaves with natural microstructures as substrates were covered by the silver nanoislands by magnetron to prepare a low-cost, environment-friendly and mass production surface-enhanced fluorescence (SEF) substrate (Ag-WL substrate). The best SEF substrate was selected by repeatly certifying the fluorescence intensity of 10^-5 M Rhodamine B (RB) and 10^-5 M Rhodamine 6G (R6G) aqueous solutions. The abundant semi-spherical protrusions and flake-like structures on the surface of the Ag-WL substrate produce high-density hot spots, which provides a new and simple idea for the preparation of biomimetic materials. The results of 3D finite-different time-domain (FDTD) simulation show that the nanoisland gap of semi-spherical protrusions and flake-like structures has produced rich hotspots. By adjusting the time of magnetron sputtering, the enhancement factor (EF) was as high as 839 times, relative standard deviation (RSD) reached as low as 10.7%, and the substrate was very stable and repeatable, which shows that Ag-WL substrate is trustworthy. Moreover, semi-spherical protrusions provide stronger surface-enhanced Raman scattering (SERS) effects compared to flake-like structure. What is more surprising is that the detection limit of the substrate for toxic substance crystal violet (CV) is as low as 10^-10 M.