栽培与野生黄花蒿中化学组分的FTIR表征及青蒿素含量比较分析

本研究运用FTIR技术,对栽培和野生黄花蒿不同部位化学成分的红外光谱特征进行指认,并比较分析两者不同部位青蒿素含量差异。结果显示：酰胺、芳香类物质均以栽培黄花蒿茎和叶片中多;可溶性多糖和糖苷类物质,栽培与野生黄花蒿茎中含量相近,但是,叶片中含量以栽培黄花蒿高;纤维素类物质,栽培茎少于野生茎,而两种黄花蒿叶片的纤维素含量相近。与青蒿素标准品比较,栽培和野生黄花蒿不同部位青蒿素含量有一定差异,其中栽培叶最高,其次是野生叶,栽培茎的含量最低。所以,运用FTIR技术可以快速判断栽培和野生型黄花蒿主要化学成分的差异,本研究对黄花蒿的引种驯化和良种选育工作有一定指导意义。     

Measurement of interharmonics in power network based on all phase FFT time shifting and phase difference

The harms brought by interharmonics have attracted people’s attention more and more. The research of interharmonics is based on the actual measurement of the interharmonics in power network. An interharmonics detection method of all phase fast Fourier transform (apFFT) time shifting and phase difference is proposed in order to overcome the defects of the bigger measurement error brought by traditional FFT algorithm. By adopting apFFT algorithm and adjusting sample rate, we suppress spectrum leakage of all 0.1 times integer time harmonics including fundamental. Frequency and amplitude corrections are obtained through main spectrum line phase difference. The apFFT main spectrum lines phase values without correction are directly taken as phase values. The concept is clear and the results are direct. The algorithm has the advantage of strong anti-interference between harmonics. The simulation results show that the proposed method can detect amplitude, phase and frequency of interharmonics with high precision. The algorithm provides a new effective way for power network interharmonic detection and analysis.     

仪器分析实验教学新模式开发——以傅里叶红外光谱仪教学为例

天津农学院为了培养学生准确掌握和使用先进分析仪器的能力,开设了仪器分析课程。以傅里叶红外光谱仪教学为例,探讨了改革傅里叶红外光谱仪的实验教学内容、教学模式、教学方法,使学生的实验技能得到提高,培养学生良好的实验素质和严谨的科研作风。     

Textural Ordination Based on Fourier Spectral Decomposition: A Method to Analyze and Compare Landscape Patterns

We propose an approach to texture characterization and comparison that directly uses the information of digital images of the earth surface without requesting a prior distinction of structural ‘patches’. Digital images are partitioned into square ‘windows’ that define the scale of the analysis and which are submitted to the two-dimensional Fourier transform for extraction of a simplified textural characterization (in terms of coarseness) via the computation of a ‘radial’ power spectrum. Spectra computed from many images of the same size are systematically compared by means of a principal component analysis (PCA), which provides an ordination along a limited number of coarseness vs. fineness gradients. As an illustration, we applied this approach to digitized panchromatic air photos depicting various types of land cover in a semiarid landscape of northern Cameroon. We performed ‘textural ordinations’ at several scales by using square windows with sides ranging from 120 m to 1 km. At all scales, we found two coarseness gradients (PCA axes) based on the relative importance in the spectrum of large (> 50 km⁻¹), intermediate (30–50 km⁻¹), small (10–25 km⁻¹) and very small (<10 km⁻¹) spatial frequencies. Textural ordination based on Fourier spectra provides a powerful and consistent framework to identifying prominent scales of landscape patterns and to compare scaling properties across landscapes.     

n维热传导方程的经典解

给出了n(n＞2)维Fourier变换及其性质,并借助它们及Euler积分给出了一类高维热传导方程的Cauchy问题的经典解.     

Transverse shape analysis of xylem ground tissues by Fourier transform image analysis I: trial for statistical expression of cell arrangements with fluctuation

Periodic cell arrangements of tracheids in Cryptomeria japonica and Agathis sp., and that of wood fibers in Magnolia obovata were examined by Fourier transform image analysis (FTIA). The angular distribution functions on power spectral patterns (PSPs) transformed from the dot maps were traced. As well as this conventional method, we developed the line convolution method and domain transformation for more correct analysis of radial and tangential arrangements. Cell arrangements became clear in Cryptomeria and Agathis. Fluctuations were expressed by the standard deviation (σ) or the relative standard deviation (σ_r) so that we could compare the characteristics of both woods. In Cryptomeria, the most provable distance between tracheids along radial files was 36.7 µm with 17% fluctuation, whereas the tangential interval was 28.3 µm with σ_r of 24%. In Agathis, the radial diameter was 35.1 µm with σ_r of 23% and the tangential interval was 41.5 µm with σ_r of 23%. In Magnolia, the maximal periodicity of wood fibers was 15.8 µm and 20.5 µm along and between radial files, respectively, although the fluctuations could not be estimated because of the remarkable interruptions by numerous vessels.     

热处理对全脂大豆蛋白质分子结构特征、溶解度和体外消化率的影响

【目的】研究热处理对全脂大豆蛋白质分子结构特征、溶解度和体外消化率的影响及三者之间的相关性。【方法】以全脂大豆为样本,对其进行湿热法(120℃高压(0.1 MPa)灭菌锅加热7.5min)和干热法(120℃烘箱干燥15min)处理,同时设膨化全脂大豆粉不作加热处理。使用傅立叶红外光谱(FTIR)技术,定量计算蛋白质分子结构特征(酰胺Ⅰ带、酰胺Ⅱ带、酰胺Ⅰ带/酰胺Ⅱ带、蛋白质二级结构中α-螺旋、β-折叠及α-螺旋与β-折叠的比值),并采用体积分数0.2%KOH溶液定氮法和胃蛋白酶-胰酶制剂两步酶解法,分别对大豆样品蛋白质溶解度和粗蛋白体外消化率进行分析,用Pearson方法分析各指标间的相关性。【结果】不同热处理条件显著影响了3种大豆样品蛋白质的分子结构特征、溶解度和体外消化率,且以对膨化全脂大豆的影响最大。蛋白质酰胺Ⅰ带、酰胺Ⅱ带的峰高和峰面积与其溶解度和体外消化率呈显著正相关关系(P0.05);而蛋白质酰胺Ⅰ带与酰胺Ⅱ带峰高比值与其溶解度和体外消化率呈显著负相关关系(P0.05),蛋白质酰胺Ⅰ带与酰胺Ⅱ带的峰面积比值与其溶解度和体外消化率也呈显著负相关关系(P0.05);α螺旋含量、α螺旋/β折叠值与蛋白质溶解度和体外消化率呈极显著正相关关系(P0.001);无规则卷曲含量与蛋白质溶解度和体外消化率呈显著正相关关系(P0.05);而β-折叠含量与蛋白质溶解度和体外消化率呈极显著负相关关系(P=0.002);并且蛋白质溶解度与体外消化率呈极显著正相关关系(P0.001)。【结论】得到了一组新的蛋白质分子结构特征数据,而且蛋白质的分子结构特征、溶解度和体外消化率三者之间存在密切的相关性关系。     

红外光谱结合元素分析法研究SRB对煤的降解

利用傅里叶红外光谱(FTIR)技术,对淮南潘二煤层煤样在接种硫酸盐还原菌(SRB)前后煤样组分的结构变化特征及规律进行研究,同时结合元素分析技术进行进一步分析。结果表明,煤样经过SRB细菌降解后,S元素、N元素均有不同幅度变化,其中,S元素均有减小的趋势,N元素有小幅度的增加趋势。C、H元素变化不明显,同时SRB细菌将煤中能降解利用的有机物降解后,煤样中含氧官能团相对含量下降、羟基官能团含量有所上升。SRB细菌的降解利用改变了煤中有机物成分含量及物质结构。     

按时间抽取基2的FFT算法的实现

详细介绍按时间抽取的傅立叶快速变换算法的基本原理,深入分析其特点,介绍了其程序实现的思想和具体内容。