Materials Literature
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Role of organic matter In a medium where clay minerals are almost absent and organic matter abundant, the latter obviously plays a big role in soil properties. Retention of water and basic cations is correlated with organic-matter content.
Thanks to the studies of M. Bornand, and by underscoring the evolution of the coarse fractions, the Luvisols Rhodic of the Rhône valley have enabled us to develop our concepts of pedogenesis still better. In these soils, in the B horizons, the carbonates dissolve in place. Igneous rocks are weathered in situ to form c…
Role of seasonal alternations In Mediterranean climate, the amount of calcium extracted increases very markedly after a dry period. Observations have shown that desiccation provokes retraction of the clays and detachment of a thin weathered film on the surface of the coarse calcite particles buried in the soil. This…
Established in 1964, the IUCN Red List of Threatened Species has evolved to become the world’s most comprehensive information source on the global conservation status of animal, fungi and plant species.
The solubility of CaCO3 in water is such that it hinders the growth of only some plants. But the actual calcium content in the soil solution is not always the maximum. It depends on the nature of the solid phase. A test has been developed for this. A measured excess of ammonium oxalate (NH4)2C2O4.H2O is added to a soi…
Portland cement is manufactured as follows. A calcareous material (limestone) and a siliceous material (clay, shale) are ground together, usually with the addition of an iron powder in certain proportions, to form a raw meal (for dry technology), or a slurry (wet technology), which is fed into a rotary kiln and calcin…
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Bin Zhang, Lanjv Mei, Haifeng Xiao; Nanofracture in graphene under complex mechanical stresses. A…
Abstract Review: 114 refs.
Synthesis The principal minerals presented form a broad, more or less continuous assemblage. Let us start from the structure of allophane and postulate, without prejudging the mechanisms: • if the tube is elongated, it is becoming imogolite, • if it is folded longitudinally and finally opens up completely to give a…
In the above chapter we have presented two ‘objective’ systems for classifying soils: WRB and Soil Taxonomy. Objectivity is a major plus point but it leads to giving excessive prominence to study of the profile that has become ‘deified’ (Gaucher 1977). Even before pedologists, designers of the classifications of livin…
Collagen fibrils are present in the extracellular matrix of animal tissue to provide structural scaffolding and mechanical strength. These native collagen fibrils have a characteristic banding periodicity of ~67 nm and are formed in vivo through the hierarchical assembly of Type I collagen monomers, which are 300 nm i…
This study presents the problem of designing, manufacturing and testing of some protective systems made from composite materials which can simultaneously perform the next requirements: noise absorption for middle and high range frequencies, noise insulation for low frequencies, vibration damping in order to avoid nois…
采用Ti、Si、TiC、金刚石磨料为原料, 通过放电等离子烧结(SPS), 制备了Ti 3 SiC 2 陶瓷结合剂金刚石材料. 研究结果表明, Ti-Si-2TiC试样经SPS加热的过程中位移、位移率和真空度在1200℃时发生明显变化, 表明试样发生了物理化学变化. XRD分析结果表明1200℃时试样发生化学反应生成了Ti 3 SiC 2 . 随着温度升高, 试样中Ti 3 SiC 2 含量逐渐增加. 当烧结温度为1200℃、1300℃、1400℃和1500℃时, 产物中Ti3SiC2含量分别为65.9%、79.97%、87.5%和90.1%. 在Ti/Si/2TiC粉料中添加适量的金刚石5%和10%进行烧结, 并未抑制Ti 3…
Nanotechnology in the intensive care: Intravascular biocompatibility of carbon nanomaterials - effect of carbon nanotubes on blood platelets. EFFECT OF CARBON NANOTUBES ON BLOOD PLATELETS Carbon nanotubes (CNTs) are among the principal materials currently used in biomedical nanotechnologies. CNTs possess superior mech…
Electron optics exploits the analogies between rays in geometrical optics and electron trajectories, leading to interesting insights and potential applications. Graphene, with its two-dimensionality and photon-like behavior of its charge carriers, is the perfect candidate for the exploitation of electron optics. We sh…
Classification In the US Soil Taxonomy, the brown soils are Inceptisols and soils enriched with clay in the B are Alfisols, characterized by an argillic horizon. But even if a soil that has an argillic horizon is, by priority, classified in the Alfisols, it may also be a Mollisol, Spodosol (surface podzolization) or…
Nitisols (earlier Nitosols) are found in very dry climates. They are less mature than Ferralsols and do not exhibit thick mottled altérites at depth, so characteristic of Ferralsols. They are very red and form on basic rocks (volcanic rocks, limestone). In the field, we often see intergrades between Ferralsols and Nit…
Return to kaolinite In northeastern wBrazil, the top kaolinite layer can be up to 10-m thick (Truckenbrodt et al. 1991). This is a sort of geochemical paradox. On the one hand, between the base and the middle of the profile, the kaolinite is destroyed and iron is concentrated. On the other hand, higher in the profil…
Differentiation of catenas The soils on slopes are often arranged in a typical manner from the top to the bottom and are genetically linked. Those on the upper slope supply to those of the bottom: (i) water, (ii) ions and/or (iii) solid materials. Then we have a soil chain or catena. Let us take an example. Granite…
Abstract Review: 40 refs.