Threshold reduction of stimulated Brillouin scattering by Stokes seeds via acousto-optic effect

We present a method of threshold reduction of stimulated Brillouin scattering by importing Stokes seeds, which are generated from the light passing through the Brilloun medium via an acousto-optic medium. To realize the scheme, the acousto-optic medium and the Brillouin medium should be of the same material, and the frequency of the transducer must be identical with the Brillouin shift. Essentially, the transducer and the acousto-optic medium constitute a special acousto-optic shifter. Calculations suggest that it is easy to reduce the SBS threshold by at least one magnitude and enhance the reflectivity remarkably by this scheme.     

Rapid method for identifying highly productive varieties of cotton by a selective process

Screening of genetically enhanced cotton varieties with a high content of protein markers, proteinase inhibitors, was carried out for the first time. It was found that only 5 of 68 studied cotton selection lines were resistant to wilt, black root rot, and gummosis. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 43–45, January–February, 2008.     

Formation and characterization of mechanochemically generated free lignin radicals from olive seeds

In this study, formation and quantification of mechanochemically generated free radicals of lignin were evaluated after the extraction of lignin from olive seeds and detailed lignin characterization was performed. Lignin was extracted from crushed olive seeds as an insoluble solid using Klason method. Isolated lignin was mechanochemically grinded under cryo conditions using Cryomill and particlesizes were determined by using Zeta Sizer, structural changes were followed by XRD and FTIR-ATR; thermal stabilities were tracked by TGA and DSC. In order to enable solubility demanding studies (such as ¹H‑NMR and GPC), acylation of lignin was accomplished. ESR measurements were completed to prove the nature of the radicals. Free radicals cavenging activity of olive seed lignin was determined and quantified using 2-diphenyl-1-picrylhydrazyl (DPPH) method. Number of created mechanoradicals (per gram of olive seed lignin) was calculated from the corresponding UV‑Vis spectra. Finally, morphological changes of the lignin over cryomilling was evaluated using SEM.     

新疆十字花科部分杂草种于微形态的研究

本文对新疆的十字花科9属9种杂草种子形状、大小、颜色及内部特征进行了描述，对种子外形、种皮进行电镜扫描，发现种皮微形态特征在种与种之间有明显的差异，并根据种皮微形态特征编制了分种检索表．     

近红外光谱的玉米种子穗腐病特征提取与判别模型研究

玉米种子穗腐病是危害玉米产量的主要病害之一。利用近红外光谱开展了玉米种子穗腐病判别模型研究。246粒玉米种子由吉林省农业科学院海南育种基地提供,其中96粒玉米种子为穗腐病染病样本,其他150粒玉米种子为同种玉米正常样本。利用MATRIX-Ⅰ型傅里叶近红外光谱仪采集了样本800～2 500 nm范围的近红外光谱信息,并对样本近红外光谱数据利用多元散射校正（MSC）进行预处理。结合玉米内部有机物质的近红外光谱的敏感波段和样本近红外光谱吸收峰挑选了4个优选区间,并采用相关系数法(CA)、连续投影算法（SPA）和竞争性自适应重加权算法（CARS）三种不同原理的特征波长提取算法分别提取了4（1 362,1 760,2 143和2 311 nm）、5（1 227,1 310,1 382,1 450和1 728 nm）和10（1 232,1 233,1 257,1 279,1 313,1 688,1 703,1 705,2 302和2 323 nm）个特征波长。以提取得到的特征波长作为玉米种子穗腐病判别模型输入变量,用0-1（染病-正常）表示样本染病状况作为输出真实值建立支持向量机（SVM）模型,使用网格搜索法结合十折交叉验证法对模型参数进行优化。结果表明,CA-SVM,SPA-SVM和CARS-SVM三种判别模型中训练集和测试集建模准确率均在90%以上。该研究成果为玉米种子病害诊断装置提供了模型基础,且针对优选区间进行特征波长选择的方式也可以为建立其他种子病害判别模型提供参考。     

Influence of sequential exogenous pretreatment and contact ultrasound-assisted air drying on the metabolic pathway of glucoraphanin in broccoli florets

In this investigation, the combinations of exogenous pretreatment (melatonin or vitamin C) and contact ultrasound-assisted air drying were utilized to dry broccoli florets. To understand the influences of the studied dehydration methods on the conversion of glucoraphanin to bioactive sulforaphane in broccoli, various components (like glucoraphanin, sulforaphane, myrosinase, etc.) and factors (temperature and moisture) involved in the metabolism pathway were analyzed. The results showed that compared with direct air drying, the sequential exogenous pretreatment and contact ultrasound drying shortened the drying time by 19.0–22.7%. Meanwhile, contact sonication could promote the degradation of glucoraphanin. Both melatonin pretreatment and vitamin C pretreatment showed protective effects on the sulforaphane content and myrosinase activity during the subsequent drying process. At the end of drying, the sulforaphane content in samples dehydrated by the sequential melatonin (or vitamin C) pretreatment and ultrasound-intensified drying was 14.4% (or 26.5%) higher than only air-dried samples. The correlation analysis revealed that the exogenous pretreatment or ultrasound could affect the enzymatic degradation of glucoraphanin and the generation of sulforaphane through weakening the connections of sulforaphane-myrosinase, sulforaphane-VC, and VC-myrosinase. Overall, the reported results can enrich the biochemistry knowledge about the transformation of glucoraphanin to sulforaphane in cruciferous vegetables during drying, and the combined VC/melatonin pretreatment and ultrasound drying is conducive to protect bioactive sulforaphane in dehydrated broccoli.     

Relationships between Nitrogen Translocation and Accumulation in Growing Plant Parts of Grain Legumes

Abstract

Grain legumes absorbed mineral ¹⁵N at every stage of development and transported it directedly (just as symbiotically fixed ¹⁵N₂) into the plant parts growing at the respective stage. The ¹⁵N accumulation in the grains after long-lasting ¹⁵N supply can be ascribed, for the major part, to a secondary ¹⁵N translocation after a temporary incorporation into older plant parts (leaves, stem). Inhibition experiments with antibiotics revealed no direct relation between the accumulation of amino acid ¹⁵N in growing pods and seeds and the protein synthesis in this target organs. It may include, however, processes of (active ?) uptake and transport with a possible contribution of carrier systems specific for distinct amino acids.     

Synthesis of a Au‐on‐Pd Heteronanostructure Stabilized by Citrate and its Catalytic Application

The preparation of Au‐on‐Pd heteronanostructure (HNS) using citrate‐stabilized polycrystalline Pd nanoparticles (NPs) as the seeds is described. The resulting Au‐on‐Pd HNS is characterized and it is found that the formation of Au‐on‐Pd HNS depends greatly on a ratio between Pd seeds and AuCl₄^? ions added and the optimal molar ratio is 10:1. If fewer AuCl₄^? ions are added (Pd/Au ratio is 100:1), the growth of Au NPs only occurs on part of the Pd seeds’ surface. The addition of more AuCl₄^? ions (Pd/Au ratio is 5:1) hinders the growth of Au NPs on the Pd seeds’ surface. To demonstrate the catalytic performance, the electrochemistry oxidation of ethanol and the reduction of p‐nitrophenol by NaBH₄ are chosen to examine the catalytic activity of Au‐on‐Pd HNS. Pd seeds, Au NPs, and poly(vinyl pyrrolidone) (PVP)‐stabilized PdAu nanoalloy are used as the references for comparison. In the first reaction, the catalytic reactivity of Au‐on‐Pd HNS is better than that of corresponding pure Pd or Au NPs, while the opposite occurs for the latter reaction. The catalytic activity of Au‐on‐Pd HNS is much higher than that of PVP‐stabilized PdAu nanoalloy.     

可见-近红外多光谱数据对水稻种子成活率的判定

种子活性受到存储条件的影响很大。收集了真实情况下受到不同存储条件影响的种子,通过发芽实验验证了其成活率存在差异。再从中选择适量的种子样本,采集其单颗种子的可见-近红外反射光谱,运用不同的光谱预处理技术,结合不同的机器学习建模手段,以区分不同成活率的种子。比较了不同的光谱预处理方法,比如标准反射光谱校正、多元散射校正等。从识别准确度的角度,认为标准反射光谱校正的方法,能够很大程度上提升不同存活率种子的光谱差异性,从而经过机器学习判断达到更高的识别准确度。同时比较了支持向量机、 K邻近和距离判别分析等机器监督学习建模方法,发现利用标准反射光谱校正的方法结合距离判别分析,能够对种子样本实现完全准确的判定。更进一步,为了满足实际运用中快速识别的要求,将高分辨率的光谱数据压缩成为低分辨率多通道带通光谱数据,这样可以大大降低的光谱数据长度,节约各种机器学习器在训练和判断中所用的时间。使用简化过后的多通道带通光谱数据判定种子存活率,其识别准确度仍然接近90%。充分说明了,利用多通道宽带光谱数据,并选择合适的机器学习建模方式,足以满足实际选种产业的一般性需求,有潜力作为未来粮种成活率快速鉴别的技术手段。还采用了多种带通宽度以简化光谱,分析比较不同带通宽度对识别精度的影响。总体来说由于带宽增大,数据量减少,识别速度更快,但是识别精度降低。从10~50 nm改变光谱带宽,标准反射校正后的简化光谱的识别精度从87.50%下降到58.75%。在实际运用中,需要权衡识别速率和预期识别精度,合理的选择带宽。验证了根据简化后的可见近红外反射光谱,能够较快速且准确的识别水稻种子存活率,为以后的基于带通滤波片的快速种子存活率识别奠定了基础。