超声波法提取啤酒花中总多糖的工艺

采用超声波法提取啤酒花中总多糖.采用正交试验设计,以总多糖含量为评价指标进行实验.最佳提取工艺为:超声提取2次,加12倍量的水,每次40min,超声功率为160W.本提取工艺合理,啤酒花中总多糖提取率较高.     

新疆紫穗槐中总黄酮的提取与含量测定

用超声波辅助乙醇溶液浸提法和索氏提取法提取新疆地方植物药材紫穗槐中黄酮化合物并进行含量测定.以芦丁为对照品,NaNO2-Al(NO3)3-NaOH体系为显色剂,利用分光光度法在510nm处测定提取物中的总黄酮的含量.校准曲线为A=11.825C-0.0139,r=0.9992.超声提取法所得总黄酮的含量以芦丁计算为2....     

一种改进型多组分气体的Tikhonov正则化特征光谱提取方法

针对FTIR光谱分析数据计算量大,具有相同基团的多组分混合气体交叉灵敏度过高,以及在线分析过程中基线漂移等问题,提出了一种改进的TR2-1(Tikhonov 2norm-1norm)正则化特征变量提取法。该方法借鉴TR1和TR2模型的基本思想,引入谱线距离和谱线系数绝对值最小化两个约束项来保证所提取特征量的准确度,消除基线漂移所带来的影响,并结合上述两种模型建立了不适定问题的最优化求解通式。该通式有效地克服了经验法和实验法确定正则矩阵和参数所带来的误差。实验以浓度为0.01%~20%的甲烷、乙烷、丙烷、正丁烷、异丁烷、正戊烷和异戊烷气体为例进行了特征光谱选取。结果表明,对于浓度为0.2%的甲烷气体,其预测误差平方和仅为2.6×10-4,可决系数达到0.959 2,分析准确度高,有效增强了TR正则法的实用性。     

水稻中的纳米硅及其紫外吸收

为了了解水稻中硅的亚显微结构及其紫外吸收特性,根据强酸不会腐蚀SiO₂玻璃的事实,选择湿消化方法分离水稻中的硅体。以浓硫酸和硝酸混合液分别处理水稻叶片和稻壳,经多级沉降分离出其中的硅体。X射线光电子能谱结果表明硅体距离表面10 nm以内碳相对质量为35.05%,远高于硅体表面(5.88%),说明硅质壁能够阻止强酸进入硅体内部,避免硅体内氧化,保持硅体结构完整和相对独立的理化性质。电镜显示硅体SiO₂结构致密,由1～2 nm的SiO₂凝胶粒子粘聚而成,纳米颗粒相互融合组成排列方向一致的纳米棒,内部还有微米尺度(≤1μm)和纳米尺度(≤1～2 nm)的隙孔。颖壳硅体最大吸收位于285 nm;叶片纳米硅对紫外辐射的吸收极其有限,表明水稻颖壳和叶片硅体对紫外辐射具有不同的抵抗机制。     

Noncommutative differential geometry with higher-order derivatives

We build a toy model of differential geometry on the real line, which includes derivatives of the second order. Such construction is possible only within the framework of noncommutative geometry. We introduce the metric and briefly discuss two simple physical models of scalar field theory and gauge theory in this geometry.Partially supported by KBN grant 2 P302 168 4.     

红光皂甙元及其两个甾体皂甙的NMR研究

从番麻(Agave americana L.)发酵的叶汁中分离得到红光皂甙元(hongguanggenin)、Cantalasaponin-1及一个新的甾体皂苷Agameroside-1. 运用2D NMR技术,包括DQF ¹H-¹H COS Y,HSQC,HMBC,HSQC-TOCSY,ROESY等技术,首次全归属了3个甾体化合物的氢和碳的化学位移,并总结了红光皂甙元的甙化位移效应,从而修正了文献中部分碳信号归属以及甙元的甙化位移效应.     

Limitations and guidelines for measuring the spectral width of ultrashort light pulses with a scanning Fabry–Pérot interferometer

The measurement of the spectral width of ultrashort light pulses using a Fabry–Pérot interferometer (FPI) is investigated. It is shown, numerically and experimentally, that the measured width critically depends on the pulse properties (such as pulse shape, pulse duration, frequency chirp and wavelength) and on the properties of the FPI (such as the mirror spacing and the mirror reflectivities). The obtained results are of particular importance if the spatial length of the short light pulses is comparable or even shorter than the distance between the FPI mirrors. The derived guideline indicate that the actual spectral width of the ultrashort light pulses is measured with good accuracy only if the finesse F≥40 and the round trip time of the light pulses inside the Fabry–Pérot interferometer is approximately one to three times the pulse duration. Received: 17 December 1999 / Revised version: 14 April 2000 / Published online: 5 July 2000     

Spectral Investigation of Phosphorus Compounds in Spinacia Oleracea Using Fourier Transform Infrared Method

The study uses the Fourier transform infrared spectroscopy method to evaluate the influence of phosphogypsum from the soil on the growth and accumulation of nutrients in Spinacia oleracea. Attenuated total reflectance spectra of Spinacia oleracea roots and stems originated from plants cultivated on 28% to 52% phosphogypsum enriched soil have been studied in the 4000–600 cm^?1 area. The structure of the infrared absorption bands for spinach roots and stems and for the soil where plants were grown was analyzed. Thus, it was observed that phosphorus–oxygen bonds contribution can be identified both in roots and stems absorption spectra. The significance of the research is the possibility to use the infrared investigation as rapid technique, particularly useful for agriculture, to study the extraction and assimilation process of the compounds containing phosphorus and nitrogen from the soil in which the spinach seedlings grew. In the case of this study, it was observed that the absorption of phosphorus in the spinach roots and stems has not the same effect. The analysis of obtained data indicated that the assimilation of phosphorus from phosphogypsum enriched soil induces changes in spinach roots structure that are most likely due to an increase synthesis of proteins, rather than to a decrease in carbohydrates quantity.