AbstractNi nanoparticles where obtained from a Ni sample milled with Ar ions by using a Gatan precision ion polishing system, normally used for Transmission Electron Microscopy (TEM) sample preparation. Deposition of Ni nanoparticles was performed over two different surfaces: on a double sided carbon tape and, on a Cu grid covered with collodion film. A continuos film of Ni was characterized, over the carbon tape by SEM and EDAX techniques. The last surface was analysed by TEM. In both cases, a thin film composed of Ni nanoparticles, was founded and result obtained by TEM, show a nanoparticle diameter of about 4 nm.
It has been well known that Au single crystal undergoes reconstruction in vacuum as well as in acidic solutions at negative electrode potentials. The reconstruction is lifted when electrode potential sweeps to positive values. Taking into account of these facts we considered when Au particles grow on an electrode in solution at different electrode potentials, morphology of the particles may be different. Based on this idea, we investigated formation of Au, Pt and Au-Cu alloy particles grown in solutions and observed icosahedral and decahedral particles of Au and Pt formed at negative potentials. These particles are identical with multiply twinned particles (MTPs) observed in vacuum.Particles were electrodeposited on an amorphous carbon film which was evaporated on a collodion film supported by a Au mesh as required for viewing in a transmission electron microscope (TEM). A three-compartment electrochemical cell was employed at room temperature with Pt wire counter electrode
A hemoperfusion system has been developed in wich very small charcoal particles (average diameter 40 μm) are embedded and immobilized in a collodion film (Filmadsorber). In vitro studies revealed that the absorption of bile acids by these small charcoal particles is superior to that by larger ones (size: 0.5 to 5 mm) as used in commercially available adsorbers. In vivo studies confirmed these results: dogs with ligated bile ducts were subjected to hemoperfusion through different types of charcoal adsorbers. Bile acid clearances of filmadsorbers containing less charcoal than the commercials were significantly higher.
A reader has pointed out that our article on paints for warts (December 9, 1977, p. 97) should have included the BNF preparation, Salicylic Acid Collodion (salicylic acid 12% in flexible collodion). It differs from Salactol and Duofilm in that it contains no lactic acid, and 12% instead of about 17% salicylic acid. Clinical trials with it have not been published, but its ingredients suggest that it should be effective. It seems likely that a higher concentration of salicylic acid than 12% would increase the efficacy of the paint. The contribution of lactic acid is uncertain; if it prevents complete drying of the collodion film it might facilitate the release of salicylic acid to the skin. Controlled trials are needed, and reformulation of the paint should be considered when the BNF is revised.
The photovoltaic effects of free and bound acriflavine were studied to find the elemenatary processes in photochemical behaviours of the dye. The observed photopotential in aqueous acriflavine solution is positive or negative against the dark electrode, depending on pH. The positive sign implys that the photoreduction of dye is more predominant than the photooxidation. The negative sign is obtained when the photooxidation is the predominant reaction.Using the electrode coated directly or indirectly with a very thin film of acriflavine-dispersed collodion, the contributions from photo-reduction and -oxidation to the photopotential were separated. The spectral sensitivity of photopotentials gives us an useful information about the oxidationreduction mechanism of bound dyes. The photo-ejection of an electron from the excited singlet state of dye molecule, which was considered by LIM and others1 to be responsible for the delayed fluorescence of acriflavine in rigid media, seems to be favourable for understanding of photopotential properties at shorter wavelengths of excitation.
AbstractThe formation of hexagonal and cubic forms of ice was studied by the use of a cold stage in an electron microscope within the temperature range −90° to −180° C. Ice crystal specimens were made on cold substrates, i.e. a collodion film, gold foil, or copper grid on the specimen holder of the cold stage. The hexagonal form of ice formed on the cold substrates at temperatures from−90° to−100° C. At −100° to −130° C, both hexagonal and cubic forms of ice were detected. From −130° to −160° C only cubic ice was found. At temperatures below −160° C, minute crystals of cubic ice were detected. No transformation of the structural form of ice from hexagonal to cubic or from cubic to hexagonal occurred when the temperature of the specimens was varied in the range −90° to −160° C. The lattice constants of hexagonal and cubic ice, and the coefficient of thermal expansion of ice were calculated from the experimental results.
Trace Elemental Determination Using a Portable Total Reflection X-Ray Fluorescence Spectrometer with a Collodion Film Sample Holder