Statistically periodic processes and toeplitz(α by β) matrices

If each element in a Toeplitz matrix is replaced by an by matrix and the original constraints preserved, the result is a doubly infinite matrix with periodic structure called a toeplitz_{( by)} matrix. Such matrices are a basic tool for describing, generating, estimating, filtering, synchronizing, and analyzing information-theoretic functions for statistically periodic processes.     

Fluoro-organofunctional silicon compounds. Synthesis of acetoxy,carbethoxy and hydroxy derivatives

The synthesis of fluoro-organosilicon compounds containing acetoxy, carbethoxy, or hydroxy groups in the organic portion of the molecule is described.     

The application of chelate systems to partition chromatography: preliminary paper

It has been found possible to retain solutions of chelating agents on a solid supporting medium, and in this paper preliminary investigations are reported which were carried out to determine the extraction behaviour of radioactive copper between an aqueous hydrochloric acid phase and a solution of dithizone in an organic solvent retained on silica gel. Chloroform was found to be a very satisfactory solvent and carbon tetrachloride was also used. For both of these solvents the extraction vs. acidity curves were found to be similar to the corresponding liquid-liquid extraction. The high values for the fraction extracted show that this method would provide a useful technique for the concentration of copper from aqueous solution, and the similarity between the liquid-liquid and liquid-solid extractions suggests that it may be possible to adapt conventional liquid-liquid extractions to work on the column principle.     

The extraction of mercury by dithizone retained on silica gel

A silica gel-dithizone-chloroform phase is suitable for the quantitative batch extraction of certain metals. The extraction of mercury from a chloride phase by such a support has been investigated and the effect of varying acidity, free ligand acid concentration, and chloride ion concentration has been determined.     

Metal-specific interactions of H2 adsorbed within isostructural metal-organic frameworks

Diffuse reflectance infrared (IR) spectroscopy performed over a wide temperature range (35-298 K) is used to study the dynamics of H(2) adsorbed within the isostructural metal-organic frameworks M(2)L (M = Mg, Mn, Co, Ni and Zn; L = 2,5-dioxidobenzene-1,4-dicarboxylate) referred to as MOF-74 and CPO-27. Spectra collected at H(2) concentrations ranging from 0.1 to 3.0 H(2) per metal cation reveal that strongly red-shifted vibrational modes arise from isolated H(2) bound to the available metal coordination site. The red shift of the bands associated with this site correlate with reported isosteric enthalpies of adsorption (at small surface coverage), which in turn depend on the identity of M. In contrast, the bands assigned to H(2) adsorbed at positions >3 ? from the metal site exhibit only minor differences among the five materials. Our results are consistent with previous models based on neutron diffraction data and independent IR studies, but they do not support a recently proposed adsorption mechanism that invokes strong H(2)···H(2) interactions (Nijem et al. J. Am. Chem. Soc.2010, 132, 14834-14848). Room temperature IR spectra comparable to those on which the recently proposed adsorption mechanism was based were only reproduced after contaminating the adsorbent with ambient air. Our interpretation that the uncontaminated spectral features result from stepwise adsorption at discrete framework sites is reinforced by systematic red shifts of adsorbed H(2) isotopologues and consistencies among overtone bands that are well-described by the Buckingham model of molecular interactions in vibrational spectroscopy.     

Zement

Ohne Zusammenfassung     

Die titrimetrische Bestimmung von Magnesium

Ohne Zusammenfassung     

Nachweis und Bestimmung der Halozene

Ohne Zusammenfassung