Phosphonomethylation of 2-aminoethanethiol and thiazolidine. An unexpected product

Phosphonomethylation of 2-aminoethanethiol and thiazolidine gives the unexpected dimethylene diphosphonic acid 6.     

A scheme for sequential separation of thorium,lanthanides, uranium in geo-materials and their ICP-OES determination

Journal of Radioanalytical and Nuclear Chemistry - Neutral complexes of thorium and lanthanides with 2,3-dihydroxynaphthalene and anionic complexes of uranium with the same chelating agent in...     

NOVEL UNSYMMETRICAL N,N-BIS(METHYLENE)BISPHOSPHONIC ACIDS OF α,ω-DIAMINES. PREPARATION AND CHARACTERIZATION OF [[(2-AMINOETHYL)IMINO]BIS(METHYLENE)]BISPHOSPHONIC ACID AND [[(6-AMINOHEXYL)IMINO]BIS(METHYLENE)]BISPHOSPHONIC ACID

Abstract

Reaction of ethylenediamine with phosphorous acid and formaldehyde in molar ratio 1:2:2 gives [[(2-aminoethyl)imino]bis(methylene)]bisphosphonic acid (2a) as the major product. Similarly, reaction of hexamethylenediamine with phosphorous acid and formaldehyde in molar ratio 1:2:2 yields [[(6-aminohexyl)imino]bis(methylene)]bisphosphonic acid (2b) which is isolated either as [[(6-carbobenzoxyaminohexyl)imino]bis](methylene)]bisphosphonic acid (3b) or as [[6-(N-benzoylamino)hexyl)imino]bis(methylene)]bisphosphonic acid (4b). Removal of the carbobenzoxy group with HBr from 3b or the benzoyl group with HCl from 4b gives pure [[(6-aminohexyl)imino]bis(methylene)]bisphosphonic acid (2b). All compounds were characterized by ¹³C NMR, ³¹P NMR and elemental analysis.     

Equivalent Gaussian measure whose R-N derivative is the exponential of a diagonal form

A simple necessary and sufficient condition, on a trace-class kernel K, is given in order to demonstrate the existence of a measurable (relative to the completed product σ-algebra) Gaussian process with covariance K. Using this result, sufficient conditions are given on the means and the covariances (relative to two equivalent (~) Gaussian measures P and P_λ) of a process X so that the Radon-Nikodým (R-N) derivative $\text{dp}{}_{\mathrm{\lambda }}\text{dP}$ is the exponential of the diagonal form in X. Analogues of the last two results in the setup of Hilbert space are also proved.     

Scaling relation for determining the critical threshold for continuum percolation of overlapping discs of two sizes

We study continuum percolation of overlapping circular discs of two sizes. We propose a phenomenological scaling equation for the increase in the effective size of the larger discs due to the presence of the smaller discs. The critical percolation threshold as a function of the ratio of sizes of discs, for different values of the relative areal densities of two discs, can be described in terms of a scaling function of only one variable. The recent accurate Monte Carlo estimates of critical threshold by Quintanilla and Ziff [Phys. Rev. E76, 051115 (2007)] are in very good agreement with the proposed scaling relation.     

A modified method for the determination of uranium in Nb/Ta minerals by LED fluorimetry

A modified LED fluorimetry determination of uranium in Nb/Ta minerals has been developed. The mineral is brought into solution by fusion with mixed phosphate flux (NaH₂PO₄, H₂O and Na₂HPO₄). Iron quenches uranium fluorescence when it is present above the ratio of (iron to uranium) 100. Uranium is separated in ethyl acetate by solvent extraction and then stripped back into pyrophosphate buffer (pH ~ 7) prior to its LED fluorimetry determination. This modified method has been applied for the determination of uranium in synthetic mixtures and Nb/Ta minerals including Certified Reference Materials (X1807) with high degree of accuracy and precision.

     

Improvement in the Performance of Composite Cathode via Solid Electrolyte for High Electrochemical Performance of Li–S Battery

Commercialization of Li–S in present scenario is obstructed by poor performance of cathode and its compatibility with electrolyte used. Here in this work, in order to improve the electrochemical performance all solid state Li–S battery, solid electrolyte (SE) formed by composition of lithium sulfide (Li₂S) and phosphorus pentasulfide (P₂S₅) combinedly called LPS is used. The modified carbon in the form of graphene oxide (GO) and reduced graphene oxide (rGO) as additive is used to provide better electron conduction pathway. High conductivity of the order 10⁻⁴ S cm⁻¹ of prepared LPS overcomes the major drawback of insulating nature of sulfur. The coin cells are fabricated by using above mentioned material as a cathode material, LPS as SE, and lithium foil as anode. The prepared nanocomposites are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) to study structural and morphological properties. Energy dispersive X-ray spectroscopy (EDS) images of the cathode surface confirms the uniform spreading of material. The electrochemical performance of coin cell is studied by Galvanostatic charge-discharge plot at 0.1 C to check the compatibility of composite and electrolyte prepared. The cells having additive material GO and rGO with host sulfur show better results as compared to the cell having pristine sulfur.     

Study of structure and optical luminescence of C+6 (80 MeV) ion irradiated CdS: Fe system

Iron doped CdS nanocrystals have been synthesized by using aqueous solution precipitation method. Samples of CdS:Fe have been subjected to irradiation using C⁺⁶ (80 MeV) under of 1×10¹³ ions/cm². For characterization, X-ray diffraction (XRD), Photoluminescence (PL) and Optical absorption studies have been performed. The system has been found in hexagonal phase having particle size distribution 18–20 nm. Photoluminescence intensity has been found to decrease, while optical band gap has been found to increase in irradiated samples.     

Synthesis, Characterization and Phosphodiester Bond Cleavage Studies of the Dinuclear, Thioacetatocobalt(II) of 3-methylsulfanylpropionic Acid Complex

A new dinuclear cobalt(II) complex containing monothioacetate and 3-methylsulfanylpropionate ligands was synthesized and fully characterized by spectral, magnetic moment, electrochemical, elemental, thermal and FAB mass analyses data. In order to explore the role of labile metal complexes in promoting phosphodiester hydrolysis, kinetic and mechanistic studies were performed. The hydrolyses of ethyl 4-nitrophenylphosphate (ENPP) and the bis(4-nitrophenyl)phosphate (BNPP) complex are catalytic, as determined by the observations of both rate enhancement and turnover. The pH versus rate profile indicates that deprotonation of the metal-coordinated water occurs to form the active catalyst.