圆筛藻亚微结构的几种图像显示技术

通过S250MKⅢ型扫描电镜对圆筛藻亚微结构的显示图像,介绍该扫描电镜的几种扫描模式,分析各种图像的特点,对仪器的开发利用和亚微结构的研究、鉴别分析手段作些探索。     

Hydrodynamic pressures and forces on quadrant front face pile supported breakwater

Quadrant front face pile supported breakwater is a combination of semicircular and closely spaced pile breakwaters which couples the advantages of these two types. This type of structure consists of two parts. The bottom portion consists of closely spaced piles and the top portion consists of a quadrant solid front face on the seaside. The leeward side of the top portion with a vertical face would facilitate the berthing of vessels. An experimental investigation on this breakwater model in a wave flume is carried out for three water depths. For each water depth, three different spacings between the piles were adopted for the investigation. The dynamic pressures exerted along the quadrant front face due to regular waves were measured. The variation of dimensionless pressures with respect to scattering parameter for different gap ratio (spacing between the piles/diameter of pile) and for relative pile depth (water depth/pile height) are presented and discussed. In addition, the dimensionless total forces exerted on the breakwater model as well as its reflection characteristics as a function of scattering parameter are reported.     

正交设计和方差分析应用于悬浮物和沉积物的EDAX分析条件试验

本文用正交试验和方差分析对悬浮物和沉积物粉末样品的EDAX分析进行了条件试验和数据处理,找出影响试验结果的主要因素和最佳分析条件,提高了分析结果的准确性。     

球形棕囊藻溶血毒素对兔红细胞作用的AFM观察

溶血性毒素是有毒藻类分泌较多的一类毒素,具有溶血活性。运用光学显微镜和原子力显微镜(AFM)观察了球形棕囊藻Phaeocystis globosa溶血毒素对兔红细胞的溶血现象。结果显示,经毒素处理后的兔血红细胞边缘凹凸不平,只剩下一小部分残骸。该毒素可能由于其双亲性质与血红细胞膜表面的膜脂连接,产生脂溶效应,使细胞膜破坏。     

长牡蛎死因初探

本文对广西北海市海涂养殖的长牡蛎大量死亡的原因作了研究。电镜检测结果表明，在其外套膜、肝脏和中肠组织已吸入与积累了大量的直径为０．１～１．１０μｍ的球状有机化合物，未见微生物病原体感染，故该市海涂长牡蛎大量死亡的原因是其体内积累了大量的球状有机污染物而严重中毒引起的。     

The role of sediments in the phosphorus cycle in Lake Lugano. II. Seasonal and spatial variability of microbiological processes at the sediment-water interface

P, Fe, Mn, and S species were analyzed in water samples from the sediment-water interface collected at four seasonally different times during the course of a year at two sampling sites in the southern basin of Lake Lugano (Lago di Lugano). The results reveal the strong influence of the biogeochemical processes in the sediment on the chemical composition of the lake water above. Consumption of oxygen and nitrate under oxic to microoxic conditions in the water column as well as sequential release of reduced manganese and iron under anoxic conditions was observed as a direct or indirect consequence of microbially mediated degradation of organic matter. The seasonal pattern observed for the release and the retainment of dissolved reduced iron and manganese correlates well with the one for dissolved phosphate. Iron, manganese and phosphorus cycling are coupled tightly in these sediments. Both sediment types act as sinks for hydrogen sulfide and sulfate. An inner-sedimentary sulfur cycle is proposed to couple iron, manganese and phosphorus cycling with the degradation of organic matter. Nutrient cycling at the sediment-water interface might thus be driven by a microbially regulated electron pumping mechanism. The results contribute to a better understanding of the role of sediment processes in the lake's internal phosphorus cycle and its seasonal dynamics.     

Simultaneous operation of opposing reaction mechanisms: The influence of matrix heterogeneity on post-kinematic garnet crystallization in an inverted metamorphic sequence

Metapelites from the inverted Barrovian sequence in the Sikkim Himalaya (northeast India) are shown to be largely continuous with respect to their bulk rock compositions, microstructures and pressure–temperature–time–deformation (P–T–t–D) histories. However, the upper garnet–lower staurolite zone demarcates a region of microstructurally anomalous post-kinematic garnet populations contained within strongly segregated matrices. The different microstructures within samples from this region cannot be attributed to differences in their thermobarometric histories or bulk compositions, but are instead interpreted to represent an otherwise unexposed level of the Daling Group that is now exposed along a post-metamorphic thrust splay. These heterogeneous samples contain several discrete garnet populations that progressively crystallized with increasing P–T. Garnet populations that experienced the most protracted growth now form complex polycrystals that exhibit crystallographically controlled and morphologically irregular interfaces adjacent to micaceous and quartzofeldspathic domains respectively. Electron backscatter diffraction indicates that these polycrystalline garnet structures contain numerous coalesced porphyroblasts that are structurally uncorrelated across their grain boundaries. However, a crystallographically preferred orientation at the polycrystal scale is interpreted to derive from epitaxial crystallization of early-formed garnet porphyroblasts on precursor mica. Later-nucleated porphyroblasts within polycrystals preferentially concentrated towards quartzofeldspathic domains, with the overall nucleation distribution likely controlled by a complex interplay between chemical heterogeneities, strain partitioning and epitaxial crystallization. The subsequent growth of these polycrystals was equally spatially heterogeneous; it was moderated by differences in the efficiency of grain boundary transfer between quartzofeldspathic and micaceous domains that precluded thin section-scale chemical equilibration. In contrast to samples from Sikkim containing more typical porphyroblastic populations in continuous and disseminated matrices, heterogeneous availability of garnet-forming components within this strongly layered matrix is shown to have resulted in grain-scale variations in growth rates and the spatial juxtapositioning of interface-controlled microstructures and locally equilibrated chemical compositions with those that were transport controlled.     

Geological Characteristics and Occurrence of Gold in the Xiling Gold Deposit,Jiaodong Peninsula北大核心CSCD

西岭金矿床是胶东金矿集区内近来新发现的超大型破碎蚀变岩型金矿床(475吨@4.56 g/t),位于著名的三山岛金矿床的东侧。本文在详实的野外地质观察的基础上,系统介绍了西岭金矿床的基础地质特征,并运用光学显微镜和扫描电镜观察,结合电子探针分析,系统研究了西岭金矿床金的赋存状态。西岭金矿床大量金矿物(银金矿和自然金)主要赋存在Ⅱ阶段石英-黄铁矿和Ⅲ阶段灰石英-多金属硫化物脉中。西岭金矿床金矿物主要有晶隙金、裂隙金和包体金三种赋存状态,以晶隙金为主。金的主要载体矿物为黄铁矿,次为石英、黄铜矿和方铅矿等。金矿物粒度大小包括粗粒金、中粒金、细粒金和微粒金,以细粒-微粒为主。金矿物形态有粒状、叶片状、线状、钩状、枝杈状和哑铃状等,以粒状为主。金矿物成分以Au和Ag为主,含微量的Cu、Cr、Fe、Ni、Te、S等元素。金成色为685~831,以银金矿为主,含少量自然金。综合地质和地球化学特征,西岭金矿床为蚀变岩型金矿床,是由早白垩世中温岩浆热液充填-交代形成。     

中国首次发现的氟闪叶石矿物学特征

闪叶石族矿物是富含Sr、Na、Ca和Ba等的钛硅酸盐矿物的总称,迄今共有19个矿物种,其中的氟闪叶石矿物首次发现于巴西Serrote山碱性岩中。本文利用电子探针和X射线衍射仪等分析测试手段,从化学成分和晶体结构等方面对产出于中国辽宁赛马碱性岩体中的闪叶石族矿物进行了详细的矿物学特征研究,发现其中常呈柱状、针状和纤维状集合体产出的闪叶石的晶体化学式为(Sr_1.00Na_1.00)_Σ2.00Ti₂(Na_1.98Sr_0.33Mn_0.26K_0.12Mg_0.10Ca_0.09Ba_0.05)_Σ2.93(Ti_0.69Fe³⁺_0.33Al_0.02)_Σ1.04(Si_3.80O₁₄) O₂(F_1.16OH_0.84)_Σ2.00,属于单斜晶系,空间群为C2/m,晶胞参数a=19.271 9(8) Å,b=7.077 9(3) Å, c=5.388 2(2) Å, β=96.780(2)°, V=729.84(5) ų, Z=2。上述矿物学特征均与巴西发现的新矿物氟闪叶石的矿物学特征一致,表明赛马碱性岩体产出的氟闪叶石堪称该矿物种在中国的首次发现。不仅如此,赛马碱性岩体也有闪叶石产出,而且,迄今已发现多个新矿物,寓示该岩体仍有良好的新矿物发现前景。