基于叶片光学属性的作物叶片水分含量反演模型研究

叶片含水量是反映作物生理特性的一个重要参数,对生态环境的研究具有重要意义。采用小波分析方法,分析叶片含水量对反射率的影响特征,建立综合利用多波段信息的作物叶片水分含量反演模型。基于PROSPECT模型的辐射传输理论,推导出由叶片反射率光谱的小波系数反演叶片水分含量C_W的理论模型。利用六种常用的小波函数,对叶片组分水、干物质和白化基本层的吸收光谱进行小波分解。选取对水分变化最敏感,同时对其他组分不敏感的分解尺度和波段位置,找到能稳定突出水的光谱特征的小波系数。结果表明：bior1.5小波函数在尺度为200 nm,波段位置为1 405和1 488 nm的小波系数具有上述特征。建立由叶片反射率光谱的bior1.5小波系数反演叶片水分含量C_W的反演模型,模型有两个转换系数a和Δ都受叶片结构参数N的影响。利用PROSPECT模型生成模拟光谱数据集,校正建立的叶片水分含量反演模型中的两个转换系数a和Δ,并与LOPEX93实验光谱数据集结合验证反演模型。结果表明：反演模型不仅比传统基于植被指数的统计模型在精度上有提高(反演值与实测值的R2最高达到0.987),而且更加稳定,普适性更高。研究表明,小波分析方法在利用高光谱数据反演作物叶片水分含量方面具有独特的优势。     

糖尿病人头发中的铬、锰、铁与铜含量水平

采用催化极谱方法分析了 98例 (糖尿病人 47例 ,对照组健康人 5 1例 )头发样品中的微量元素铬 (Cr)、锰 (Mn)、铁 (Fe)、铜 (Cu)、锌 (Zn)、硒 (Se)和宏量元素钙 (Ca)、镁 (Mg)含量水平。结果显示 ,糖尿病人头发样品中的Cr( 0 99± 0 75 )× 1 0 - 6 、Mn( 1 3 0± 0 90 )× 1 0 - 6 和Cu( 8 5 0± 1 40 )× 1 0 - 6 分别显著低于对照组头发样品中的Cr( 1 5 5± 0 97)× 1 0 - 6 、Mn( 2 3 0± 1 60 )×1 0 - 6 和Cu( 1 0 40± 2 90 )× 1 0 - 6 ,Cr、Mn、Cu的显著性水平分别为P =0 0 0 1 ,P <0 0 0 1和P <0 0 0 1。而糖尿病人头发样品中的Fe( 1 9 0 0± 9 0 0 )× 1 0 - 6 ,则显著高于对照组头发样品中的Fe( 1 6 0 0± 8 0 0 )× 1 0 - 6 ,其显著性水平P为 0 0 2 3。但糖尿病人与健康人头发样品中的Zn、Se、Ca和Mg含量水平之间的差别并不显著。这些结果与其他一些研究所得的结论基本一致。     

介绍一个针对非化学专业的化学科普实验——头发中微量元素的测定

结合中国科学技术大学的学期改制,在夏季学期面向全校非化学专业的低年级本科生开设了“生活中的化学科普实验”公选课程,课程内容多为与生活密切相关的热点问题。“头发中微量元素的测定”是其实验项目之一。该实验将学生自己的头发作为分析对象,合理地设计教学内容和实验步骤,以期激发学生对化学实验的兴趣,提高学生对化学学科的认识。     

高效液相色谱-串联质谱法分析毛发中甲基苯丙胺和苯丙胺手性对映异构体

建立了高效液相色谱-串联质谱（HPLC-MS/MS）分析毛发中甲基苯丙胺与苯丙胺对映异构体的手性分离方法。采用SUPELCO Astec CHIROBIOTIC^® V2手性液相色谱柱,以甲醇-含0.1%（v/v）甲酸的20 mmol/L乙酸铵水溶液（99：1,v/v）为流动相进行手性分离。结果表明,甲醇高温水浴超声法能较好地提取苯丙胺类化合物,且峰形较好（拖尾因子>0.95）。S-（+）-甲基苯丙胺、R-（-）-甲基苯丙胺、S-（+）-苯丙胺和R-（-）-苯丙胺在15~300 ng/mg范围内线性关系良好,相关系数均大于0.99;甲基苯丙胺和苯丙胺的检出限分别为0.1 ng/mg和0.15 ng/mg,定量限分别为0.4 ng/mg和0.5 ng/mg;日内精密度均≤6.8%,日间精密度均≤11.4%。采用所建方法对50余嫌疑人毛发进行手性分析,检出单一S-（+）-甲基苯丙胺和S-（+）-苯丙胺的占70%,同时检出S-（+）-甲基苯丙胺、R-（-）-甲基苯丙胺、S-（+）-苯丙胺和R-（-）-苯丙胺的占18%。该法简单快速,精密度好,可为实际法医毒物鉴定案例中的毛发手性分析提供技术支持与科学依据。     

The transport network of a leaf

Modern leaves, the energy factories of plants, are the products of a 400-million-year evolutionary race towards improved efficiency and robustness. As such they have evolved two sophisticated transport systems, the xylem and the phloem, which irrigate the surface of the leaf blade, distribute water and nutrients, and collect the products of photosynthesis. In this review, we discuss the development and function of these two networks. Additionally, with a focus on the global topological and architectural features, we present an overview of the evolution of reticulation through the lens of transport network optimization theory and analyze some aspects of the physics of flow.     

Two New Natural Methoxyflavonoids from Leaves of Murraya paniculata(L.) Jack

Two new natural methoxyflavonoids and two known methoxyflavonoids were isolated from the ethanol fraction of the leaves of Murraya paniculata(L.) Jack. The two new natural methoxyflavonoids were elucidated as 2'-hydroxy-3,4,5,3',4',6'-hexamethoxychalcone(1) and 6,7,8,3',4'-pentamethoxyflavanone(2) on the basis of ¹³C NMR and mass spectra. The two known methoxyflavonoids were identified as 3'-hydroxy-5,7,4'-trimethoxyflavone(3) and 2'-hydroxy-3, 4, 4', 6'-tetramethoxychalcone(4).     

稻瘟病、玉米锈病和蚕豆锈病叶的傅里叶变换红外光谱研究

利用傅里叶变换红外光谱(FTIR)研究了水稻、玉米、蚕豆正常叶和稻瘟病叶、玉米和蚕豆锈病叶。结果显示,其红外光谱均主要由多糖、蛋白质的振动吸收谱带组成。光谱整体相似,差异主要表现为光谱峰位、峰形及吸收强度比。三种作物正常叶的二阶导数光谱在1 750～1 500 cm-1范围内的相关系数差异明显。水稻正常叶与稻瘟病叶的吸收强度比A_{1 056}/A_{1 652};蚕豆正常叶与锈病叶的吸收强度比A_{1 652}/A_{2 920};玉米正常叶和锈病叶(非病斑部位)吸收强度比A_{1 056}/A_{2 920},玉米正常叶和玉米锈病叶(病斑处)吸收强度比A_{1 652}/A_{2 920},均呈现出病变叶吸收强度比正常叶要小的趋势。表明他们之间的多糖和蛋白质的含量存在差异。     

高效液相色谱法测定染发剂中的22种染料成分

建立了染发剂中22种染料成分的高效液相色谱测定方法。使用Discovery RP-Amide C16柱(250 mm×4.6 mm,5 μm),以乙腈-0.025 mol/L磷酸盐缓冲液(pH 6.0,含0.1%的庚烷磺酸钠离子对试剂)为流动相,流速为1.0 mL/min;使用二极管阵列检测器(DAD),检测波长为260 nm和280 nm,柱温为25 ℃。该方法除了对低浓度的甲苯-2,5-二胺硫酸盐、2-甲基雷锁辛和N,N-二乙基甲苯-2,5-二胺HCl外,对其他各组分的含量测定值的相对标准偏差(RSD)均小于10%,加标回收率为77.6%～122.8%。该方法简便、准确、快速,适于氧化型染发剂中染料成分的检测。     

Determination of methamphetamine and amphetamine in abusers' plasma and hair samples with HPLC-FL

This paper describes highly sensitive HPLC methods for the determination of amphetamine (AP) and methamphetamine (MP) in abusers' plasma and hair samples. AP and MP were derivatized with the fluorescent reagent, DIB-Cl, to yield a highly fluorescent DIB-derivatives of AP and MP, which were then analyzed by HPLC with fluorescence detection at excitation and emission wavelengths of 325 and 430 nm, respectively. The separation was achieved on an ODS column with isocratic mobile phases composed of acetoniltrile and citrate buffer (55:45, v/v) for plasma samples and of acetonitrile-methanol-citrate buffer (45:20:37.5, v/v/v) for hair samples. The limits of detection were less than 0.87 ng/mL and 0.12 ng/mg in plasma and hair samples, respectively, for both AP and MP. The methods were then applied to the determination of MP and its metabolite AP in plasma obtained from two cases of illegally ingested MP and in one of the cases' hair received later. Case I was treated with dialysis; samples before and after dialysis were analyzed by the described method. After dialysis for 5 h, the total plasma levels of AP and MP decreased from 720 to 190 ng/mL. For case II, MP and AP levels were monitored for 3 days after digestion. Total plasma levels decreased from 57 ng/mL in the day of digestion to 11 ng/mL after 3 days. In hair samples, AP and MP could also be detected in very low concentrations.     

水杨基萤光酮－溴化十六烷基三甲基铵分光光度法测定锌

水杨基萤光酮－溴化十六烷基三甲基铵分光光度法测定锌黄青瑜，童式国，刘小虎，杨映辉（四川大学化学系，成都６１００６４）关键词：锌，水杨基萤光酮，人发，分光光度法微量锌的测定方法是比较多的，如近年来发展较快的有高灵敏显色的萤光酮衍生物等。而水杨基萤光酮，...