Synergic extraction of Eu(III) and Tb(III) by 2-thenoyltrifluoroacetone and tribenzylamine

Synergic extraction of Eu(III) and Tb(III) with 2-thenoyltrifluoroacetone (HTTA) and tribenzylamine (TBA) as neutral donor ligand has been studied in chloroform from perchlorate media at lower pH range. The stoichiometric composition of the adduct was established as M(TTA)₃ · 3TBA for both the elements, having a coordination number 9. The formation constants K_3,0 and K_3,3 and stability constant _3,3 of the organic phase reaction have been calculated. The effect of temperature on the extraction has also been studied. The adducts are stabilized by the large exothermic enthalpy change. The calculated thermodynamic functions such as H, S and G were used to elucidate the mechanism of synergism in which the coordination numbers of the lanthanide ions increased.     

Free radical grafting of monomers to polydienes. IV. Kinetics and mechanism of methyl methacrylate grafting to polybutadiene

The radical grafting of methyl methacrylate (MMA) onto polybutadiene (PBD) in benzene solution at 60°C is more efficiently induced by benzoyl peroxide (BP) than by azoisobutyronitrile (AIBN). PBD exerts a pronounced retardation on the polymerization of MMA and the grafting efficiency is governed by the ratio of rubber to monomer in the system. With BP as initiator, a fairly simple kinetic expression, relating grafting efficiency with reactant concentrations, can be derived by making certain approximations, including the neglect of termination grafting. The experimental data are reasonably consistent with this equation and yield acceptable values of several kinetic parameters. With AIBN, termination grafting is more significant. In consequence the relevant kinetic equation can be only qualitatively validated.     

Long noncoding RNAs in neuronal-glial fate specification and oligodendrocyte lineage maturation

Background  

Long non-protein-coding RNAs (ncRNAs) are emerging as important regulators of cellular differentiation and are widely expressed in the brain.     

Luminescence studies on the blue-green emitting Sr4Al14O25:Ce phosphor synthesized through solution combustion route

New blue-green emitting Sr₄Al₁₄O₂₅:Ce³⁺ phosphor is reported in this paper. The polycrystalline samples of phosphor were prepared by the conventional solution combustion method and checked for crystallization and phase by X-ray diffraction. Photoluminescence studies reveal the emission at 472 and 511 nm that correspond to the transition between lowest T_2g level of the 5d state to the ²F_5/2 and ²F_7/2 ground state levels of the Ce³⁺. The excitation at 275 nm corresponds to O²⁻→Ce⁴⁺ charge transfer processes to lowest 5d state of Ce ion (T_2g). Phosphorescence decay procedures reveal the existence of slow, medium, and fast component involved in the process. Varying the γ-dose (1-6 Gy), thermoluminescence (TL) measurements were made and glow curve maximum is obtained at 383 K. The phosphor seems to follow a first-order kinetics due to non-shifting T_m property. The T_m-T_stop method followed by the repeated initial rise method is applied to determine the distribution of activation energies and corresponding maximum positions. Chi-square minimization procedures provide the appropriate peak positions and other trapping parameters. From deconvolution results, the activation energies are found to be 0.84 and 1.06 eV, while the frequency factor is of the order of 10¹⁰ and 10¹¹ s⁻¹, respectively.     

Study of viscosity behavior and retanning properties of sulfonated glutaric dihydrazide formaldehyde condensate under different reactant ratios

Sulfonated glutaric dihydrazide formaldehyde condensates with less than 0.05% free formaldehyde were prepared through controlled reaction of glutaric dihydrazide, sodium metabisulfite, and formaldehyde in three processing steps. Mole ratio of sodium metabisulfite/glutaric dihydrazide (S/GDH) was varied from 0.1 to 0.5 and that of formaldehyde/glutaric dihydrazide (F/GDH) from 1 to 3. The effects on viscosity and fluidity of resins were observed with varying degrees of sulfonation and changeable mole ratio of formaldehyde/glutaric dihydrazide. Viscosity of resins showed increasing trend with increasing mole ratio of formaldehyde/glutaric dihydrazide and decreasing trend with increasing mole ratio of sodium metabisulfite/glutaric dihydrazide. Increase in viscosity of resins was due to increase in molecular weight of polymer chains. After gaining a critical molecular weight during condensation, resins turned into gel form. The resins were comparatively applied on chrome tanned cow hide against commercial sulfonated urea formaldehyde powder resin (Resin UFT).     

Thermoanalytical investigation of 1,2-diimidazoloethane complexes of copper,mercury and cadmium by TG-DTG-DTA techniques in static air atmosphere

The iodide complexes of transition metals with 1,2-diimidazoloethane (DIE) of the general formula MLI₂, (M=Cu(II), Hg(II), Cd(II); L=1,2-diimidazoloethane) were prepared and studied by means of thermogravimetry (TG/DTG) and differential thermal analysis (DTA) techniques. Their compositions were investigated by elemental analysis in order to ensure their purity and structural elucidations were based on conductivity measurements, room temperature magnetic measurements, proton NMR, XRD and IR spectra. Thermal decomposition of these distorted tetrahedral complexes and the ligand took place in two distinct steps upon heating up to 800°C, with the loss of inorganic and organic fragments. The thermal degradation of all the complexes (except for cadmium complex) in static air atmosphere started at temperatures lower than those observed for the free ligand pyrolysis. The composition of intermediates formed during degradation was confirmed by microanalysis and IR spectroscopy. The residues after heating above 740°C corresponded to metal oxide except for Hg(II) complex, which behaved differently. It was found on the basis of thermal analysis that thermal stability of the complexes increased in the following sequence: Hg(II)<Cu(II)<Cd(II).     

The structure and chemistry of hirsutic acid

By a necessary combination of chemical and X-ray studies the structure and stereochemistry of the sesquiterpenoid acid, hirsutic acid C (C₁₅H₂₀O₄) from Stereum hirsutum have been established as shown in I. An unusual rearrangement involving solid state X-irradiation has been discovered and evaluated.     

A Cancer Therapeutic Vaccine based on Clustered Tn‐Antigen Mimetics Induces Strong Antibody‐Mediated Protective Immunity

Tumor‐associated carbohydrate antigens (TACAs) are key components of cancer vaccines. A variety of vaccines based on native TACAs such as α‐Tn have shown immunogenicity and protection in preclinical animal studies, however, their weak immunogenicity, low in vivo instability, and poor bioavailability, have discouraged their further evaluations in clinical studies. A new improved vaccine prototype is reported. It is composed of four clustered Tn‐antigen mimetics and a immunogenic peptide epitope that are conjugated to a cyclopeptide carrier. The immunization of mice with this vaccine 1) was safe, 2) induced a strong and long‐lasting Tn‐specific response with IgM/IgG antibodies able to recognize native carbohydrate antigens; 3) produced high titers of IgG1, IgG2a, and IgG3 antibodies; and 4) produced a significant antibody‐dependent regression of tumors and conferred protection. Altogether, these findings pave the way for the clinical development of safe and effective therapeutic vaccines against Tn‐expressing cancers.     

Synthesis and spectroscopic characterization of Ag-Cu alloy nanoparticles prepared in various ratios

Ag-Cu alloy nanoparticles of various compositions were synthesized by the polyol process and characterized by UV-Visible, fluorescence and XRD techniques. The particle size calculated by Debye Scherrer's equation was found to decrease from 28 to18 nm with the increase in mole fraction of Cu in Ag-Cu alloy nanoparticles due to crystal lattice contraction. The appearance of the spectral peaks of alloy nanoparticles between the peaks of pure Ag and Cu revealed the formation of alloy nanoparticles. The optical properties were found to vary with composition and the Ag-Cu alloy of 1:1 composition showed a maximum value of extinction coefficient. The results of fluorescence spectroscopy revealed Cu as a quencher. Physical parameters, such as the total number of atoms in alloy nanoparticle, number of binding sites, binding constant and free energy of binding were calculated from fluorescence data.