Separation and gravimetric determination of barium using sulfadimethoxin salicylaldimine

Sulfadimethoxin salicylaldimine (SUDMSA) has been found to be a wide spectrum precipitant of a number of metal ions. The chelates are granular, stable, and quantitatively formed. SUDMSA has been utilized for the gravimetric determination of barium in the presence of Ca(II), Sr(II), Fe(III), As(III), Sb(III), Cr(III), Ag(I), Cu(II), Ni(II), Co(II), Mn(II), Cd(II), Zn(II), Hg(II), Pd(II), Mg(II), Tl(I), ZrO(II), Sn(IV). The St. of the chelate was confirmed by elemental analysis and IR data.     

Inclusive γ-production in\bar pp interactions at 0.76 and 2.0 GeV/c

The inclusive production of photons in \(\bar pp\) interactions has been studied at incident momenta of 0.76 and 2.0 GeV/c. The inclusive cross sections for γ-production and the average multiplicities of γ, «n _γ», are presented as a function of the charged prong topology. Results on the two particle correlation parametersf ⁰⁰ andf ^?0 are presented. The inclusive distributions of the Feynman variablex and of the transverse momentump _T of the photons are compared with the expectations from charged pion distributions on the basis of charge independence. A search has been made for direct γ-production in \(\bar pp\) interactions at 0.76 GeV/c by looking for events which fit uniquely the hypothesis \(\bar pp \to m\pi ^ + + m\pi ^ - + \gamma \) . An estimate of the ratio $$R = \frac{{\sigma (\bar pp \to m\pi ^ + + m\pi ^ - + \gamma )}}{{\sigma (\bar pp \to m\pi ^ + + m\pi ^ - + \pi ^0 )}}$$ is given.     

Transverse correlation of charm pairs, ψψ and partons transverse momenta

Assuming the partons within the initial hadrons to have transverse momentum we have calculated in the framework of the fusion process the transverse angular distributions of the charm pairs and of the ψψ pairs produced in hadronic collisions. The transverse angle is defined as \(\cos \phi = P_{T3} \cdot P_{T4} /(|P_{T3} ||P_{T4} |)\) wherep _T3 andp _T4 are the transverse momenta of the charm pairs/ψψ pairs. By comparing with the data we find that the effective transverse momentum of the partons is ～ 0.6 GeV/c.     

General characteristics of\bar pp interactions at low energies in terms of principal axis and impact parameter variables

The reaction configuration in momentum and position space has been investigated in detail from exclusive final states in \(\bar pp\) interactions at centre of mass energies 2.01 and 2.96 GeV. In momentum space one finds a tendency towards a planar configuration at low multiplicities. In position space, one sees the average impact parameter decreasing with increasing multiplicity. At large multiplicities, events become more phase-space like i.e., more central whereas at lower multiplicities the effect ofp _t damping can be seen.     

Tl2Ba2−xSrxCuO6: A system exhibiting a compositionally controlled superconductor-metal transition

Strontium-substituted thallium cuprates of the type Tl₂Ba_2−xSr_xCuO₆ have been synthesized for various values of x. Single phases were obtained for x ≤ 1.2. The compounds crystallize in the tetragonal structure with space group I4/mmm as the parent Tl₂Ba₂CuO₆ oxide. Both a and c lattice parameter decrease with increase in x. T_c decreases gradually from 92 to 77 K (x = 0.8). Beyond x = 1.0 superconductivity is lost. The x = 1.2 comparison is metallic down to 4.2 K.     

Nano-Impact Single-Entity Electrochemistry Enables Plasmon-Enhanced Electrocatalysis**

Plasmon-enhanced electrocatalysis (PEEC), based on a combination of localized surface plasmon resonance excitation and an electrochemical bias applied to a plasmonic material, can result in improved electrical-to-chemical energy conversion compared to conventional electrocatalysis. Here, we demonstrate the advantages of nano-impact single-entity electrochemistry (SEE) for investigating the intrinsic activity of plasmonic catalysts at the single-particle level using glucose electrooxidation and oxygen reduction on gold nanoparticles as model reactions. We show that in conventional ensemble measurements, plasmonic effects have minimal impact on photocurrents. We suggest that this is due to the continuous equilibration of the Fermi level (E_F) of the deposited gold nanoparticles with the E_F of the working electrode, leading to fast neutralization of hot carriers by the measuring circuit. The photocurrents detected in the ensemble measurements are primarily caused by photo-induced heating of the supporting electrode material. In SEE, the E_F of suspended gold nanoparticles is unaffected by the working electrode potential. As a result, plasmonic effects are the dominant source of photocurrents under SEE experimental conditions.     

Vibrational dynamics of ions in glass from fifth-order two-dimensional infrared spectroscopy

The vibrational dynamics of the first four antisymmetric stretch vibrational levels of azide in an ionic glass have been measured and correlated using a heterodyned fifth-order two-dimensional infrared pulse sequence. By rephasing a two-quantum coherence, a process not possible with third-order spectroscopy, solvent effects on the frequencies and anharmonicities of the potential energy surface are measured. Fifth-order pulse sequences are another step towards precisely controlling vibrational coherence in analogy to the manipulation of spins in NMR but with ultrafast time resolution.     

Order-disorder transitions: structural and magnetic ordering in double perovskites

Using an effective lattice gas-like model for B-B′ site ordering we study order-disorder transitions in double perovskite materials A₂BB′O₆. We motivate this effective model from a microscopic hamiltonian. Using this model, we are able to address several experimentally observed issues including nonmonotonic dependence of the degree of order on annealing temperature, and the rapid decrease of order upon overdoping with either B or B′ species. We also study ordering in the ‘ternary’ compounds A₂BB′_1−yB″_yO₆, using a variant of the Blume-Emery-Griffiths model. Several issues related to structural and magnetic ordering are discussed.     

Highly efficient (R-X-R)-type carbamates as molecular transporters for cellular delivery

The (R-X-R) motif-containing arginine-rich peptides are among the most effective cell-penetrating peptides. The replacement of amide linkages in the (R-X-R) motif by carbamate linkages as in (r-ahx-r)(4) or (r-ahx-r-r-apr-r)(2) increases the efficacy of such oligomers several-fold. Internalization of these oligomers in mammalian cell lines occurs by an energy-independent process. These oligomers show efficient delivery of biologically active plasmid DNA into CHO-K1 cells.