Stoichiometric Nature Research Articles

Properties and Effects of Laser-Induced Plasma During Evaporative Deposition of Thin Films

ABSTRACTThe properties of plasmas generated by the interaction of a pulsed CO2 laser with several solid evaporation targets were studied and the films deposited from such plasmas were characterized. A large flux (˜ 1014/cm2/s) of ions at high velocities (2 − 10 × 106 cm/s) was measured in these plasmas. ZrO2 thin films deposited by laser-assisted evaporation on room temperature substrates had crystalline-oriented structures. Low optical absorption and high refractive index values (2.15 at 632.8 nm) indicated the stoichiometric and dense nature of these films.

Microdetermination of rare earth elements in their acetylpyridine N-oxide complexes by the oxine method after oxygen flask combustion

Eleven rare earth elements (REE) were microdetermined after separation from the entity of two series of their acetylpyridine N-oxides complexes. This was performed by the oxine method after oxygen flask combustion in a single sample weight, applying gravimetric (I) and two titrimetric (II, III) procedures. This method has favorable gravimetric factors and sharp endpoints with 12-fold amplifications for titrimetric finish. The method gives an evidence and confirmation of the stoichiometric nature of these complexes. The calculated standard deviation ranges from 0.0208 to 0.0777 for the three combined procedures (I, II, and III). These procedures are more accurate and precise than complexometric and colorimetric methods applied for REE in such compounds.

Characterization of the acidic phosphoprotein of eukaryotic ribosomes using a new system of two-dimensional gel-electrophoresis

1. A modified method of two-dimensional gel electrophoresis has been developed for detecting acidic eukaryotic ribosomal proteins. 2. Using this method it has been demonstrated that the major phosphoprotein (L γ) of mouse ascites and hamster fibroblast 60-S ribosomal subunits is an acidic protein, apparently analagous to L7 12 of Escherichia coli, and not a neutral protein as previously thought. Electrophoretic resolution of phosphorylated and non-phosphorylated forms of L γ has enabled the stoichiometric nature of the phosphorylation (previously deduced from measurement of the specific radioactivity of the ATP pool) to be confirmed. 3. When ascites cells were incubated for 3 h there appeared an altered form of L γ which is most likely produced by proteolytic cleavage of the original form. The extent of phosphorylation of L γ was decreased by one-half or more in these circumstances. 4. Phosphoprotein L γ was found to be almost completely phosphorylated in both polyribosomes and monoribosomes isolated from hamster fibroblasts. Thus the function of the phosphorylation of L γ appears not to be concerned with the inactivation of ribosomes.

Etch Pit Studies of GaP Liquid Phase Epitaxial Layers

In investigations of the influence of defects on the luminescence properties of compound semiconductors, the relative importance of purely structural defects, e.g., dislocations, vs. imperfections of a chemical or stoichiometric nature, such as impurities, vacancies, etc., is invariably discussed. Recent photoluminescence studies on and have shown that dislocations are an important factor only if they are decorated with impurities. For the decorated dislocations only occur when there is also present another type of etch feature called a saucer or S‐pit. In the present report further comparisons of dislocations and S‐pits are made in material typical of that used in electroluminescent devices made by liquid phase epitaxy (LPE). The etch pit studies on LPE material have been examined in terms of using S‐pits as an observable in evaluating the device potential of different LPE layers.

The mode of potassium action on the adrenergic neuron amine transport system

Experiments with K-depleted rabbit heart slices demonstrate that extracellular K + is essential for optimal l-MA uptake, but high extracellular [K +] antagonizes amine uptake in a non-competitive manner. The data provide additional evidence for the coupled, stoichiometric nature of the Na + -anminecarrier at the adrenergic neuron membrane.

Studies in histochemistry. LXXXV. Histochemical demonstration of protein with bromsulfalein.

Bromsulfalein has been shown to provide an intense blue stain for protein with some advantages over other acid dyes that have been used similarly. The procedure is simple and requires no unusual materials. The previously established stoichiometric nature of the reaction between the anionic dye and the cationic groups of protein offer the potential use of the stain for measurement.

The interaction of rivanol with bovine serum albumin

Interaction of the cationic form of rivanol (6, 9-diamino-2-ethoxyacridine lactate) with native and modified bovine serum albumins (BSA) was studied by various physicochemical methods. Influence of pH and ionic strength on precipitation of BSA by rivanol was investigated. The amount of precipitate formed increased with pH above 7.0, and increasing the ionic strength reduced precipitation at any pH. Modification of basic groups of BSA resulted in increased precipitation below pH 8.0. Extensive methylation of COOH groups of BSA resulted in diminished or no precipitation. Presence of a soluble BSA-rivanol complex at pH 8.0 or above in the supernatant fluid was shown by electrophoresis. A number of physicochemical measurements failed to reveal significant changes in the BSA recovered from the BSA-rivanol complex. By means of equilibrium dialysis experiments, a plot of the binding data gave a straight line indicating the stoichiometric nature of the BSA-rivanol interaction. From these data the maximal number of binding sites ( n) was found to be 17 and the binding constant ( k) equal to 150. However, it was found that precipitation occurs upon the addition of more than 7 moles rivanol/mole albumin at pH 8.0, 0.10 μ. The general nature of the rivanol-BSA interaction resembles that of bivalent cations to carboxyl groups.

THE EFFECT OF TEMPERATURE UPON SOME OF THE PROPERTIES OF CASEIN

1. The investigations dealing with the properties of casein as an acid were reviewed. 2. The solubility of uncombined casein in water was measured at 5 degrees C. and found to be 0.70+/-0.1 mg. of N per 100 gm. of water. 3. Robertson's solubility measurements of casein in bases at various temperatures were recalculated and found to agree well with more recent measurements. 4. By combining the observations of several investigators, as well as the author's measurements of the solubility of casein, in base, at various temperatures, the following conclusions were reached: (a) The solubility of casein in base is affected by the temperature in a discontinuous manner. (b) There exist two ranges of temperature, one, extending from about 21 degrees to 37 degrees C. and the other from about 60 degrees to 85 degrees C. where the solubility of casein in base is practically independent of temperature. (c) From 37 degrees to 60 degrees the equivalent combining weight of casein rises from the value 2100 to about 3700 gm. 5. By comparing the values of base bound by 1 gm. of casein at the two temperature ranges with a constant, the value of base necessary to saturate the same amount of casein, it was found that the latter value is a common multiple of the former values, indicating the stoichiometric nature of the effect of temperature.