Effect of the structure of mesophyll in a leaf on the form of the spectral curve for the first derivatives of the reflection coefficients of leaves over the range 0.68–0.75 μm

It is shown that replacement of the investigated surface of a leaf by the opposite one, as well as nonuniform content of chlorophyll over a pile of leaves, may lead to a change in the form of spectra for the first derivatives of reflection coefficients of leaves. A simplified model of the reflection of a leaf is used to explain the experimental results obtained. B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 68, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 6, pp. 921–925, November–December, 1998.     

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介绍了弧光放电等离子体与梯度磁场相结合来处理植物种子这一新兴的等离子体生物技术。给出了番茄种子(中蔬6号)经不同参数的磁化等离子体处理后的生物效应及种子的抗旱性对比。结果表明:种子中脯氨酸含量明显提高,说明磁化等离子体能通过降低细胞渗透势来增加番茄抗旱性;SOD、POD活性、根系活力和ATP含量增加,表明磁化等离子体可以通过清除植物体内自由基和增强代谢来增加番茄对水分胁迫的抗性。     

种植青海大黄叶中矿物质元素研究

青海地道中药材“西宁大黄”，野生资源濒临枯竭，人工种植规模不断扩大。定期采集了青海西宁及邻近地区两年生种植大黄叶，分析测试了其矿物质元素，为西宁大黄资源的可持续开发和利用提供科学依据。研究表明，种植大黄叶中矿物质营养元素的协同性以及有效蓄积对大黄的生长具有重要意义。钠元素在大黄叶中的有效蓄积以及环境中水分的及时补给对种植大黄的生长具有重要作用。     

用微柱高效液相色谱法测定烟草样品中的植物色素的研究

植物色素是烟草中的重要成分,烟叶调制过程中色素降解完全和得当,会使烟叶香气增加,色泽上等,因此研究烟草调制过程中的色素变化具有重要意义。烟草色素的测定常用分光光度法和液相色谱法,光度法准确性较差,传统的液相色谱法样品前处理较麻烦且分离时间长。和常规高效液相色谱相比,由于微柱高效液相色谱具有流动相消耗小,分析时间短,可不分流直接和质谱连用等特点,近几年来得到了迅速发展。我们研究了用WatersXterraTMRP18微柱为固定相液相色谱法测定烟草中的植物色素,烟草中的主要色素在4.0min内可达到基分离,和常规液相色谱相比大大节约了分析时间,本方法标准回收率为94％～106％,RSD为1.6％～2.8％。将其用于烟草样品中植物色素的分析,取得满意结果。     

电感耦合等离子体质谱法测定西红柿中微量元素

采用带六极杆碰撞反应池（CCT）的电感耦合等离子体质谱法（ICP-MS）直接测定了蔬菜样品中微量和痕量金属元素。在碰撞反应池中引入He／H2（93／7）混合气，有效地消除了分子离子（ArCl^-、ArAr^＋等）对痕量砷、硒测定的干扰。比较了原子吸收光谱法和原子荧光法测定结果，两种方法获得的结果基本一致。     

Green synthesis of Pd truncated octahedrons using of firmiana simplex leaf extract and their catalytic study for electro‐oxidation of methanol and reduction of p‐nitrophenol

A facile and eco‐friendly biosynthetic route for preparing Pd truncated octahedrons (PdTOs) using firmiana simplex leaf extract was reported without any chemical reducing agents. The information of reducing components, reduction process and time were obtained by ATR‐FTIR imaging, FTIR and UV–Vis spectroscopy, respectively. TEM image revealed that more than 75% of PdNPs were composed of PdTOs with an average diameter of 9.2 nm. HR‐TEM analysis demonstrated that a single PdTO consisted of the mix of {100} and {111} crystal planes. SAED and XRD pattern confirmed the well crystalline nature of fcc structured PdTOs. The model reactions of electro‐oxidation of methanol and reduction of p‐nitrophenol (p‐NP) were adopted to explore the effects of structure and size of PdNPs on the catalytic properties. In the electro‐oxidation of methanol, the forward‐scan peak current density (If) of PdTOs was 10.05 mA cm‐2, 6.3 times and 1.9 times of PdNPs‐0 and PdNPs‐4:1, illustrating its superior electro‐catalytic property to that of spherical PdNPs. In the p‐NP reduction reaction, the apparent rate constant (Ka) over PdTOs was 0.358 min‐1, higher than spherical PdNPs‐0 (0.08 min‐1) with the similar particle size and lower than the same spherical PdNPs‐4:1 (0.562 min‐1) and commercial Pd/C (0.415 min‐1), which all about half the size of PdTOs. It has been demonstrated that electro‐chemical oxidation of methanol was a structure‐sensitive reaction, while the reduction of p‐NP was mainly dependent on the particle size of PdNPs.     

Extraction and characterization of cellulose single fiber from native Ethiopian Serte (Dracaena steudneri Egler) plant leaf

Biomaterials are renewable sources which are widely distributed, locally accessible, high possibility of recycling and biodegradation behavior. This investigation deals with the extraction and characterizing of new fiber obtained from Serte plant leaf that is found in Ethiopia. The physical, chemical and mechanical characters of the fiber had been tested and comparison with other plant fibers was done for the first time. Optimization of fiber extraction process has been done by varying the extraction variables like NaOH concentration, temperature and extraction time. Fibers possessing 56% cellulose content along with significant amount of hemicellulose, lignin and ash with tensile strength of 330?MPa were obtained. FTIR as well as X-ray diffraction analysis were also done to further analyze the fiber. This new plant leaf fiber can be another alternative resource in place of synthetic fibers depending on their application such as reinforcing polymer matrices.