基于主动学习的玉米种子纯度检测模型更新

种子纯度反映种子品种在特征特性方面典型一致的程度,提高种子纯度检测的准确性和可靠性对保证种子的质量具有重要的意义。高光谱图像技术可以同时反映种子的内部特征和外部特征,在农产品无损检测中已经得到广泛应用。利用近红外高光谱图像实现农产品无损检测的实质就是建立光谱信息与农产品品质参数之间的数学模型关系。但光谱信息易受环境、时间的影响,当待测样本的产地或者年份发生改变时光谱信息也随之改变,导致建立的模型的稳定性变差、泛化能力减弱。针对这一问题,采用主动学习算法选择具有代表性的待测样本,最终以添加最少最优的样本数来扩大原模型的样本空间,从而实现模型的快速更新,提高模型的稳定性,同时与基于随机选择算法（RS）和Kennard-Stone算法(KS)的模型更新效果进行比较。实验结果表明：在不同样本集划分比例下（1∶1, 3∶1, 4∶1）,利用主动学习添加40个新样本更新后的2010年的玉米种子纯度检测模型对2011年新样本的预测精度由47%,33.75%,49%提高到98.89%,98.33%,98.33%;利用主动学习添加56个新样本更新后的2011年的玉米种子纯度检测模型对2010年新样本的预测精度由50.83%,54.58%,53.75%提高到94.57%,94.02%,94.57%;同时基于主动学习算法的模型更新效果明显优于RS和KS。因此基于主动学习算法实现玉米种子纯度检测模型的更新是可行的。     

微区X射线荧光光谱仪研制及元素生物地球化学动态分布过程研究

微区无损分析可提供物质组成元素的原位分布信息,以揭示物质形成条件、元素动态分布过程与相互作用机理、生物代谢作用等。文章报道了实验室型微区X射线荧光(μXRF)光谱仪的研发和元素生物地球化学动态分布过程研究结果。μXRF光谱仪采用15 μm光斑的聚束毛细管X射线透镜为激发源,选用分辨率为135 eV的硅漂移探测器(SDD),样品和探测器间角度可调,使之可进行异型样品如地质样品的原位分析,利用五轴自控实现样品时空四维元素分布测定。利用该μXRF光谱仪测定了矿物-生物膜间的元素迁移和玉米种发芽过程中的元素分布,发现(1)生物膜可吸附、富集毒性元素铅,是重金属的重要汇集地,最大富集系数1.7。(2)生物膜是金属从固态矿物相经水相进入生态系统的重要途径。(3)在玉米种子中,可检测到K,Ca,Mn,Fe,Cu,Zn和Pb。Zn主要在胚乳中分布,胚中有少量Zn存在;在胚乳和胚中存在微量Fe;胚乳中存在微量Pb,胚中未观测到Pb。(4)经含Pb溶液浸泡发芽后,K在玉米种中胚和胚乳中部分富集,Fe分布在种皮和胚乳中,Cu和Zn主要在胚乳中分布;Pb主要在胚根、胚轴和胚芽中分布,且Pb在新生根中高度富集。研究表明,在种子萌发阶段,Pb等毒性元素可被植物滞留于根部,制约了其向地上部的转移,从而揭示了植物对毒性元素的耐受机制。     

Organic Electronics from Nature: Computational Investigation of the Electronic and Optical Properties of the Isomers of Bixin and Norbixin Present in the Achiote Seeds

Organic compounds have been employed in developing new green energy solutions with good cost-efficiency compromise, such as photovoltaics. The light-harvesting process in these applications is a crucial feature that still needs improvements. Here, we studied natural dyes to propose an alternative for enhancing the light-harvesting capability of photovoltaics. We performed density functional theory calculations to investigate the electronic and optical properties of the four natural dyes found in achiote seeds (Bixa orellana L.). Different DFT functionals, and basis sets, were used to calculate the electronic and optical properties of the bixin, norbixin, and their trans-isomers (molecules present in Bixa orellana L.). We observed that the planarity of the molecules and their similar extension for the conjugation pathways provide substantially delocalized wavefunctions of the frontier orbitals and similar values for their energies. Our findings also revealed a strong absorption peak in the blue region and an absorption band over the visible spectrum. These results indicate that Bixa orellana L. molecules can be good candidates for improving light-harvesting in photovoltaics.     

Seeds as Potential Sources of Phenolic Compounds and Minerals for the Indian Population

Seeds are major sources of nutrients and bioactive compounds for human beings. In this work, the chemical composition and physicochemical properties of 155 Indian seeds (belonging to 49 families) are reported. Moisture and ash were measured with reference protocols from AOAC; total polyphenols and flavonoids were measured with spectrophotometric methods after extraction with organic solvents, and mineral elements were determined by X-ray fluorescence spectrophotometry. Total phenolic compounds, flavonoids and mineral contents (Al, Ba, Ca, Cl, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, P, Rb, S, Sr, Ti, V and Zn) were found to vary in the ranges 182–5000, 110–4465 and 687–7904 mg/100 g (DW), respectively. Noticeably, polyphenol contents higher than 2750 mg/100 g were observed in 18 seeds. In addition, mineral contents >5000 mg/100 g were detected in the seeds from Cuminum cyminum, Foeniculum vulgare, Commiphora wightii, Parkia javanica, Putranjiva roxburghii, Santalum album and Strychnos potatorum. Botanical and taxonomical variations in the proximate characteristics of the examined seeds are also discussed.     

多管漩涡混合-气相色谱-三重四极杆质谱测定油茶籽中18种多氯联苯

通过比较不同吸附剂的净化效果,建立了油茶籽中18种多氯联苯(PCBs)的气相色谱-三重四极杆质谱(GCQQQ-MS/MS)检测方法。油茶籽样品用乙腈提取,加氯化钠盐析,离心分层后提取液加无水硫酸镁、C18、N-丙基二乙胺(PSA)和多壁碳纳米管(NANO)进行多管漩涡振荡分散固相净化,GC-QQQ-MS/MS多反应监测(MRM)模式进行检测。结果表明,油茶籽中18种多氯联苯具有良好的线性关系,检出限为5μg/kg,平均回收率为109.2%,相对标准偏差为2.9%~6.2%(n=3)。方法应用于3个油茶主产省份油茶籽监测,48个油茶籽样品中18种多氯联苯均未检出。     

薄片状MFI晶体无凝胶蒸汽辅助晶化制备b轴取向沸石膜

采用新型薄片状MFI沸石晶体作为晶种,通过无凝胶蒸汽辅助晶化法(gel-less steam-assisted crystallization,GLSAC)在烧结氧化硅多孔载体上制备了致密平整、b轴取向的MFI沸石膜。考察了GLSAC中模板剂浓度、釜底水量、生长温度及时间对MFI沸石膜的影响。扫描电子显微镜和X射线衍射结果显示,适量的模板剂和釡底水量能抑制晶种的面外生长。成功制备了厚度750 nm、致密平整的MFI沸石膜。制备的对丁烷异构体气体分离测试表明,25℃时,等物质的量的丁烷异构体的分离因子(SF_A/B)可达36,对正丁烷的渗透速率为1.5×10^-7mol·m^-2·s^-1·Pa^-1。     

Isolation of secoisolariciresinol diglucoside from lignan-containing extract of <Emphasis Type="Italic">Linum usitatissimum</Emphasis> seeds

An effective method for obtaining secoisolariciresinol diglucoside (SDG) purified of lignan from extract of Linum usitatissimum seeds was proposed. The lignan-containing concentrate obtained by aqueous ethanol extraction with microwave irradiation was purified using column chromatography. The structure of the compound was confirmed using IR, mass, and NMR spectra. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 21-23, January–February, 2009.     

Chemical Composition Assessment of Structural Parts (Seeds,Peel, Pulp) of Physalis alkekengi L. Fruits

In recent years there has been an extensive search for nature-based products with functional potential. All structural parts of Physalis alkekengi (bladder cherry), including fruits, pulp, and less-explored parts, such as seeds and peel, can be considered sources of functional macro- and micronutrients, bioactive compounds, such as vitamins, minerals, polyphenols, and polyunsaturated fatty acids, and dietetic fiber. The chemical composition of all fruit structural parts (seeds, peel, and pulp) of two phenotypes of P. alkekengi were studied. The seeds were found to be a rich source of oil, yielding 14–17%, with abundant amounts of unsaturated fatty acids (over 88%) and tocopherols, or vitamin E (up to 5378 mg/kg dw; dry weight). The predominant fatty acid in the seed oils was linoleic acid, followed by oleic acid. The seeds contained most of the fruit’s protein (16–19% dw) and fiber (6–8% dw). The peel oil differed significantly from the seed oil in fatty acid and tocopherol composition. Seed cakes, the waste after oil extraction, contained arginine and aspartic acid as the main amino acids; valine, phenylalanine, threonine, and isoleucine were present in slightly higher amounts than the other essential amino acids. They were also rich in key minerals, such as K, Mg, Fe, and Zn. From the peel and pulp fractions were extracted fruit concretes, aromatic products with specific fragrance profiles, of which volatile compositions (GC-MS) were identified. The major volatiles in peel and pulp concretes were β-linalool, α-pinene, and γ-terpinene. The results from the investigation substantiated the potential of all the studied fruit structures as new sources of bioactive compounds that could be used as prospective sources in human and animal nutrition, while the aroma-active compounds in the concretes supported the plant’s potential in perfumery and cosmetics.     

Chemical Characterization and Nutritional Markers of South African Moringa oleifera Seed Oils

Moringa oleifera Lam (syn. M. ptreygosperma Gaertn.) leaves are globally acclaimed for their nutritional content and mitigation of malnutrition. In most impoverished rural communities including Limpopo, Mpumalanga and KwaZulu Natal of South Africa, powdered leaves of Moringa oleifera are applied as a nutritional supplement for readily available food such as porridge for malnourished children and even breast-feeding mothers. Widely practiced and admired is also the use of the plant seed in the do-it-yourself purification of water by rural South Africans. This study aimed at identifying the chemical and nutritional marker compounds present in South African Moringa oleifera seed oils using high resolution 1-2-dimension gas chromatography in order to give scientific validation to its uses in cosmetics and particularly in culinary practices. Results obtained from two-dimension tandem mass spectrometry chemical signature revealed over 250 compounds, five times more than those reported from one-dimension gas chromatography. Whereas previous reports from gas chromatography-mass spectrometry analysis reported oleic acid (70–78%) as the major compound from oil samples from other countries, M. oleifera seed oil from South Africa is marked by cis-13-octadeaconic acid with 78.62% and 41.9% as the predominant monounsaturated fatty acid in the hexane and dichloromethane extracts respectively. This was followed by cis-vaccenic acid, an isomer of oleic acid at 51% in the acetone extract, 9-octadecanoic acid-(z)-methyl ester at 39.18%, 21.34% and 10.06% in dichloromethane, hexane and acetone extracts respectively. However, a principal component analysis with R² = 0.98 of the two-dimension tandem mass spectrometry cum chemometric analysis indicated n-hexadecanoic acid, oleic acid, 9-octadecanoic acid-(z)-methyl ester and cis-vaccenic acid with a probability of 0.96, 0.88, 0.80 and 0.79 respectively as the marker compounds that should be used for the quality control of moringa seed oils from South Africa. This study demonstrates that South African Moringa oleifera oils contain C-18 monounsaturated fatty acids similar to oils from Egypt (76.2%), Thailand (71.6%) and Pakistan (78.5%) just to mention but a few. These fatty acids are sunflower and olive oil type-compounds and therefore place moringa seed oil for consideration as a cooking oil amongst its other uses.     

Lupin (Lupinus albus L.) Seeds: Balancing the Good and the Bad and Addressing Future Challenges

Lupinus albus L. (lupine) is a legume whose grain/seed has gained increasing interest. Its recognized nutritional properties, namely a high content of protein, dietary fiber and its low fat content, make lupine a suitable alternative not only for animal protein, but also as a substitute for more processed and less balanced flours from a nutritional point of view, used in the preparation of bread, cakes and cookies, among others. In addition, its nutritional and bioactive compounds have potential benefits for human health in the prevention and treatment of some diseases. However, the existence of some anti-nutritional compounds and contaminants reveal some concern, requiring effective methods for their detection and eventual removal. This review intends to address the potential of lupine (L. albus) in food and human health and to balance the pros and cons. Nutritional and anti-nutritional components of L. albus seeds and possible contaminants of lupine seeds are examined. The potential health benefits of lupine (seeds), including energy metabolism, cardiovascular diseases, hypertension, glucose and insulin metabolism, bower function and anticonvulsant action, are discussed based on scientific evidence (both clinical trials and studies performed with animal models).