Secretory profile of metapleural gland cells of the leaf-cutting ant Acromyrmex coronatus (Formicidae: Attini)

Ants present a pair of metapleural glands located at the posterolateral end of the thorax. Because of its importance in the social organization of ants, the present study was aimed at describing the morphophysiology of this gland in three worker castes of Acromyrmex coronatus, focused on secretory activity using histological and histochemical techniques. Our findings revealed that the secretory and the storage portions of this gland are connected by extracytoplasmic portion of canaliculi that drain the secretion from each secretory cell to the collecting chamber. This secretion contains glycoproteins. In minor workers, the secretion contains higher levels of polysaccharides when compared to that of major workers, supporting the role of the metapleural gland in the maintenance of the fungus garden. The nucleus as well as cytoplasm of secretory cells were strongly positive for RNA indicating that these cells are active in the synthesis of proteins and lipids, compounds found in the final secretion. The variant of the CEC revealed that the secretory activity of the entire gland is synchronous, as all cells exhibit the result.     

声波钻进和宝长年LS250声波钻机

声波钻进是一种新的钻探技术方法，由于具有钻进速度快、岩土样保真度高、施工安全性好和环境污染少等优点，被广泛应用于环境钻探、矿物勘探、岩土工程勘察与施工等领域。本文主要介绍了声波钻进的工作原理、钻进过程、主要优点、应用领域，以及美国宝长年公司最新研制的LS250小型声波钻机的主要特点和技术性能参数。     

第1O次美国水平定向钻进年度调查——大型钻机市场走在前面

本文简要介绍了美国第10次水平定向钻进年度调查得情况，尤其是大型钻机的市场情况，以及应用行业、管材、施工穿越长度等。     

Optical properties of the synthetic nanocomposites SiO2/CdS/poly(styrene-co-maleic anhydride) and SiO2/CdS/poly(styrene-co-maleimide)

Hybrid materials consisting of SiO2/CdS particles dispersed in poly(styrene-co-maleic anhydride) and poly(styrene-co-maleimide) have been synthesized and characterized. The polymer nanocomposites were synthesised in situ in the presence of previously prepared inorganic fillers (SiO2/CdS). The nanocomposites were synthesized with the use of as-prepared or surface-modified SiO2/CdS fillers. For both types of nanocomposites, the optical properties were evaluated and the observation of size quantization effects in the optical spectra is discussed. In this context, the influence of the inorganic fillers and polymer matrices on the optical properties of the final nanocomposites was investigated.     

X-ray Raman spectroscopy of carbon in asphaltene: light element characterization with bulk sensitivity

X-ray Raman spectra of the carbon K-edge have been recorded using 6.461 keV radiation for a petroleum asphaltene. By comparison with coronene, graphite, and paraffin standards, the asphaltene spectrum is seen to be composed of contributions from saturated and aromatic carbon species. The information contained in the carbon K-edge was extracted with bulk (approximately 1 mm) sensitivity, because the Raman method used hard X-rays. This helps alleviate concerns about surface artifacts that frequently occur with soft X-ray spectroscopy of light elements. X-ray Raman spectroscopy shows great potential for characterization of light elements in fuels, catalysts, and other complex materials under chemically relevant conditions.     

泄流毁坝

对泄水建筑物泄流造成水利枢纽损伤、故障和毁坏的种种原因作了详尽的介绍。列举实例说明大坝失事的主要原因、提出了必须采取排除或减轻事故发生的多种措施和进一步研究设计流量的问题。