脱铬皮微薄片及其纤维干热性能的研究

利用热台偏光显微镜,通过考察脱铬皮微薄片及纤维的干热收缩温度(DTs)、热收缩率及其收缩曲线的变化,探讨了微薄片与纤维的耐干热性能。结果发现:DTs越高且热收缩率越小,纤维和微薄片的热稳定性越好,其由大到小的顺序均为:中层﹥肉层﹥粒面层;微薄片的热稳定性主要与纤维及纤维间的交联有关,而纤维的热稳定性主要与其本身结构有关。微薄片与纤维之间的DTs及收缩率的差值越大,纤维间的交联影响越大,反之,差值越小,纤维的影响越大;同一部位的DTs和转折点之前的收缩率均为:微薄片﹥纤维。

火成岩的交代蚀变作用及薄片鉴定

蚀变火成岩在内生矿床中特别是热液矿床中常常看着的现象,交代蚀变的岩石既然是含矿溶液和围岩交代作用的产物,而含矿溶液的上升又时常沿着裂隙或其他软弱地带而流动,因此,这种作用最剧烈的地方应该是与矿物及金属矿物相接触的围岩中。所以对这岩石薄片的研究和鉴定是找矿的科学根据。作者几年来对鉴定交代蚀变的岩石薄片有些体会,今介绍如下,供大家参考。

Relationship Between Leaf Structure and Aloin Content in Six Species of Aloe L.

The leaf structure, content and the storage location of aloin in the leaves of six species of Aloe L. were studied by means of semi-thin section, high performance liquid chromatography (HPLC) and fluorescent microscope. Results showed that all leaves consisted of epidermis, chlorenchyma, aquiferous tissue and vascular bundles. The leaves had the xeromorphic characteristics, including thickened epidermal cell wall, thickened cuticle, sunken stomata and well-developed aquiferous tissue. With the exception of thus, there were remarkable differences in leaf structure among the six species. The chlorenchyma cells were similar to palisade tissues in Aloe arborescens Mill. and A. mutabilis Pillans, but isodiametric in A. vera L., A. vera L. var. chinensis Berg., A. saponaria Hawer and A. greenii Bali. A. arborescens, A. mutabilis, A. very and A. vera var. chinensis included large parenchymatous cells at the vascular bundles, whereas no such cells were observed at the vascular bundles of A. saponaria and A. greenii. In A. arborescens, A. mutabilis and A. vera, the aquiferous tissue sheaths were present and composed of a layer of small parenchymatous cells without chloroplasts around the aquiferous tissue. While there were no aquiferous tissue sheaths in A. vera var. chinensis, A. saponaria and A. greenii. The HPLC revealed that the content of aloin was high in A. arborescens, low in A. vera, and very low in A. saponaria among the six species. The fluorescent microscopy showed that the yellow-green globule only appeared in the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath, but not in the chlorenchyma and aquiferous tissue. Consequently, the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath were the storage location of aloin. They were positively correlated with the content of aloin.

Microstructural Study of Zinc Sulfide Thin Films

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Investigation on the Morphology of Adsorbed Benzotriazole Film on Copper Surface by Scanning Tunneling Microcopy

It is observed by scanning tunneling microscopy (STM) that theadsorbed Benzotriazole (BTA) on copper is long in shape and has anirregular rectangle. The growth of BTA on copper is in the form ofpolymeric chain and mainly in one dimension rather than twodimensions. The copper surface covered by BTA becomes flatter,smoother and the roughness was smaller than that of bare copper, sothe corrosion is largely decreased. However, many grooves can be seenbetween BTA polymeric chains in which corrosion may exist to adegree.

Synthesis of flowerlike nickel particles and their microwave absorbing properties

Two kinds of nickel particles with flower-like struc~＇es assembled with a number of nano-flakes were synthesized and the relationship of their morphology and microwave absorbing properties was studied. The electromagnetic parameters of these flower-like Ni were measured with vector network analyzer at 2-18 GHz frequency and the reflection losses （RL） with different sample thicknesses were calculated. The results indicate that the flower-like nickel-wax composites with the sample thickness less than 2 mm show excellent absorbing ability. This result is expected to play a guiding role in the preparation of the highly efficient absorber.

Electron transfer from sulfate-reducing bacteria biofilm promoted by reduced graphene sheets

Reduced graphene sheets (RGSs) mediate electron transfer between sulfate-reducing bacteria (SRB) and solid electrodes, and promote the development of microbial fuel cells (MFC). We have investigated RSG-promoted electron transfer between SRB and a glassy carbon (GC) electrode. The RGSs were produced at high yield by a chemical sequence involving graphite oxidation, ultrasonic exfoliation of nanosheets, and N2H4 reduction. Cyclic voltammetric testing showed that the characteristic anodic peaks (around 0.3 V) might arise from the combination of bacterial membrane surface cytochrome c3 and the metabolic products of SRB. After 6 d, another anodic wave gradually increased to a maximum current peak and a third anodic signal became visible at around 0 V. The enhancements of two characteristic anodic peaks suggest that RSGs mediate electron-transfer kinetics between bacteria and the solid electrode. Manipulation of these recently-discovered electron-transport mechanisms will lead to significant advances in MFC engineering.

推荐一种光性矿物实习的教学工具

在没有说到这种工具以前,先根据光性矿物和岩石实习的特殊性,来说明在这类实习中的教和学两方面所存在的问题,希望教这类课程的先生们,共同想法找出解决的办法来。光性矿物在学习地质的课程中,是接触到用光学中的偏光理论来鉴定矿物的新概念。因此,在实习中怎样使理论和实践结合起来。

Fast and reliable identification of atomically thin layers of TaSe2 crystals

Deposition of clean and defect-free atomically thin two-dimensional crystalline flakes on surfaces by mechanical exfoliation of layered bulk materials has proven to be a powerful technique, but it requires a fast, reliable and non-destructive way to identify the atomically thin flakes among a crowd of thick flakes. In this work, we provide general guidelines to identify ultrathin flakes of TaSe2 by means of optical microscopy and Raman spectroscopy. Additionally, we determine the optimal substrates to facilitate the optical identification of atomically thin TaSe2 crystals. Experimental realization and isolation of ultrathin layers of TaSe2 enables future studies on the role of the dimensionality in interesting phenomena such as superconductivity and charge density waves.