Investigation on Mixed Silver Halide, Silver Cyanide and Silver Thiocyanate Systems by means of Electron Microscope

Mixed systems of silver halides, silver cyanide and silver thiocyanate were investigated by means of electron microscope. The shape of the particles formed depends greatly on the ratio of concentrations of the reacting components. Even quite small amount of one substance can change the particle shape of another one. The most characteristic electron micrographs are reproduced

Note on a Graphite-Sample with X-Ray Diagrams Free of »Orientation-effect«

We happened to obtain a sample of the residue usually collected during the decomposition of calcium cyanamide. In unpurified form it is a blackgreyish mud composed primarily of calcium and carbon. By repeated purification it might finally contain up to 99 .34% C, without Si, the rest (ash) being mainly iron oxide

Studies of Bentonites II* The Morphology of Montmorillonite Particles and the Crystal Form of Free Silica in Some Bentonites

In continuation of our investigations determinations have been made of the chemical and mineralogic composition, of the viscosity of suspensions, and of the size and morphology of the particles of bentonites, of which three kinds contained free silica in the form of quartz, one was a pure montmorillonite, whereas four contained morntmorillonite with additions of crystobalite and also a small percentage of quartz. The measurements of viscosity have shown that suspensions of bentonites containing free silica, chiefly as crystobalite, have a smaller structural viscosity and thyxotropy

A Light Scattering and Electron Microscope Examination of Monodispersed Metal Iodate Hydrosols

Monodispersed lanthanum and lead iodate hydrosols were prepared and their properties examined by means of light scattering, electron and light microscopy, and measurements of rate of deposition of particles. The sols exhibited brilliant colour bands of higher order Tyndall spectra indicating the presence of spherical particles very uniform ill sizes. Lead iodate sols, otherwise very unstable, could be stabilized by simple filtration through filter paper. This was accompanied by reversal of charge carried by the particles. The growth of lanthanum iodate was much slower. Angular distribution of light scattered by metal iodates showed typical features of monodispersed systems with spherical particles several hundred millimicrons in radius. This was confirmed by electron microscopy. Particles of a typical lanthanum iodate sol were about 700 mμ in radius, and those of lead iodate about 860 mμ. The variations in particle sizes from different preparations were considerable, and could be explained by the uncontrolled influence of the direct mixing of reacting solutions. A tentative mechanism of the formation of monodispersed metaliodate hydrosols was proposed

Chloroplast structure and function in wild-type and aurea-type leaves of the Japanese spindle-tree over their life span

The evergreen leaves of the Japanese spindle-tree (Euonymus japonicus Thunb. \u27Aureomarginatus\u27) are adapted to endure repeated freezing and thawing during the winter. We investigated the physiological and morphological characteristics of the chloroplasts in young, overwintering, and overwintered wild-type and aurea-type leaves. When developing in the shade, both leaf types during their life span maintained a well-developed thylakoid system in their chloroplasts. The photosynthesis rates were also similar. When growing in intense sunlight, the aurea variety contained chloroplasts with a reduced thylakoid system, but photosynthesis was less reduced. In spring, overwintered leaves of both varieties clearly showed ultrastructural and physiological characteristics of senescence. The senescence in aurea leaves exposed to full sunlight was more pronounced

A Light Scattering and Electron Microscope Examination of Monodispersed Metal Iodate Hydrosols

Monodispersed lanthanum and lead iodate hydrosols were prepared and their properties examined by means of light scattering, electron and light microscopy, and measurements of rate of deposition of particles. The sols exhibited brilliant colour bands of higher order Tyndall spectra indicating the presence of spherical particles very uniform ill sizes. Lead iodate sols, otherwise very unstable, could be stabilized by simple filtration through filter paper. This was accompanied by reversal of charge carried by the particles. The growth of lanthanum iodate was much slower. Angular distribution of light scattered by metal iodates showed typical features of monodispersed systems with spherical particles several hundred millimicrons in radius. This was confirmed by electron microscopy. Particles of a typical lanthanum iodate sol were about 700 mμ in radius, and those of lead iodate about 860 mμ. The variations in particle sizes from different preparations were considerable, and could be explained by the uncontrolled influence of the direct mixing of reacting solutions. A tentative mechanism of the formation of monodispersed metaliodate hydrosols was proposed

Structural changes of lamellar cells in leaves of the moss Polytrichum formosum Hedw. during winter freezing and thawing processes

The lamellar cells of winter leaves of Polytrichum formosum were studied by electron microscopy of thin sections, and the results were compared with those for spring and summer plants. Pigment content and photosynthetic activity were also analysed. The lamellar cells of winter plants, when grown at temperatures above zero, had a similar ultrastructure to those of spring and summer plants. Their pigment content and photosynthetic activity were also similar. On the other hand, the lamellar cells of frozen plants (examined at temperatures about –5 °C) were desiccated, i.e. deformed, the cytosol was shrunken, and the ribosomes and mitochondria were aggregated. The thylakoid system of their chloroplasts was irregularly arranged and the grana thylakoids were compressed. The desiccation of the cells was soon annulled when the ambient temperature rose above zero

Methorics of the Precipitation Processes. XXIV. Flocculation Phenomena of Non-Ionic Surface-Active Agents on Silver Iodide Sols

An explanation concerning the flocculation and stabilization action of non-ionic surface-active agents (NSAA) T-X-305 and T-X-705 on the negatively and positively charged silver iodide stable sols was attempted by means of tyndallometric and microscopic investigations. The flocculation phenomena were found to occur in the concentrational region of 10-7 to 10-4 mol dm·3 of triton. The influence of temperature, time, and sol concentration on the kinetics of the formation of colloid particles was also examined . The mechanism of flocculation· processes was suggested by assuming that the flocculation and stabilization of Ag! colloid in the presence of NSAA is a heterogeneous precipitation characterized by the critical concentrational and temporal parameters

Precipitation and Solubility of Uranyl Orthophosphates. II. Heterogeneous Equilibria in Solutions of: U02(NO3)2 - H3P04 - HNO3

The precipitation and dissolution of uranium(VI) from aqueous solutions containing 10-3 M uranyl nitrate and various concentrations of orthophosphoric and nitric acid is / surveyed. The concentration regions where (U02)s(P04h and U02HP04 are precipitated and/or dissolved are presented by means of typical precipitation bodies. The influence of the initial concentration ratio of nitric/ orthophosphoric acid in the precipitation system on the morphology of (U02la(P04)2 particles formed is shown by electron micrograps