Potentiometric studies of dithiooxamide with a sulphide-selective membrane electrode

The sulphide-selective electrode is applicable to the determination of dithiooxamide by titration with silver nitrate. The effect of the alkali content of the solutions on the reaction has been studied. The reaction products are silver sulphide, oxalic acid, and nitric acid. If the alkali concentration of the solution is lower than that equivalent to the acid formed during the titration, the amount of sulphide produced by hydrolysis decreases and the equilibrium potential is established more slowly.The determination is rapid and accurate in the presence of 1 M sodium hydroxide.     

A study of the reactions π−p → K1X, K1Σ and K1Y11(1385) at 3.93 GeV/c

We have investigated the final states K¹⁰(890)Σ, $\text{K}{}^{10}\text{(890)Σ}{}^0$ and K¹⁰(890) Y₁¹⁰(1385) produced in π^?p interactions at 3.93 GeV/c. We present the differential cross sections and spin density matrix elements for the resonances as functions of momentum transfer, as well as the gL and Σ⁰ polarizations. The Σ⁰ polarization is found to be positive and maximal. An amplitude analysis is performed for the K¹ Λ and $\text{K}{}^1\text{Σ}{}^0$ reactions, and it is found that one natural parity transversity amplitude is dominant for the latter.     

Magnetospectroscopy of double HgTe/CdHgTe QWs with inverted band structure in high magnetic fields up to 30 T

Magnetoabsorption in far and mid IR ranges in double HgTe/CdHgTe quantum wells with inverted band structure has been studied in high magnetic fields up to 30 T. Numerous intraband and interband transitions have been revealed in the spectra and interpreted within axial 8 × 8 k·p model. Splitting of dominant magnetoabsorption lines resulting from optical transitions from hole-like zero-mode Landau level has been discovered and discussed in terms of a built-in electric field and collective phenomena.     

Vibrational spectra and structure of trinitromethane

The vibrational spectrum of trinitromethane was interpreted in terms of the additive interatomic interaction model on the basis of experimental infrared and Raman spectra of HC(NO₂)₃, DC(NO₂)₃, HC(¹⁵NO₂)₃ and normal coordinate analysis. The frequency assignment results were used in discussing its structure. It was shown that the symmetry of trinitromethane is below C₃ in the liquid state.     

Kharasch reaction: Cu-catalyzed and non-Kharasch metal-free peroxidation of barbituric acids

It was discovered that the Kharasch peroxidation of barbituric acids proceeds both with a Cu-catalyst and without a metal catalyst. Despite the presence of possible thermal-initiated side oxidation pathways, α-tert-butylperoxybarbiturates were selectively prepared from substituted barbituric acids and tert-butyl hydroperoxide.     

The electronic structure of methyl lithium

The results of SCF—MO calculations using a large Gaussian basis set are reported for methyl lithium CH₃Li. Particular attention is paid to obtaining chemically useful informa- tion from the wavefunction, and a comparison is made with the results recently reported for NH₃Li⁺, which is isoelectronic with CH₃Li. Significant differences in their electronic structures are evident on examining the electron density and density difference maps together with population analysis indices.     

Naphthalene derivatives of a conformationally locked GFP chromophore with large stokes shifts

The active development of fluorescence microscopy requires an increase in the variety of the dyes and their characteristics. Compounds with a large Stokes shift, i.e., a large difference between the positions of the absorption and emission maxima, have attracted the interest of researchers as a tool that can be used for multicolor labeling. One of the known approaches to increase the Stokes shift is the introduction of additional polycyclic fragments. Herein, we report novel derivatives of a conformationally locked GFP chromophore containing the naphthalene ring. The proposed modification leads not only to the enhancement of the Stokes shift up to 100 nm but also leads to the noticeable red-shift of the emission and absorption spectra in contrast with the corresponding derivatives with one benzene ring.     

Vibrational spectrum and structure of the second stable rotamer of butadiene-1,3

The dependence of the calculated vibrational frequencies of the second stable rotamer of butadiene- 1,3 on the torsional angle about the central single C---C bond has been studied in the interval from 0° (planar syn-form) to 50°. The force field was described by scaled force constants obtained from CNDO/2 calculations. The best agreement between the calculated and experimental vibrational frequencies was found at 25° from the planar syn-form. The results of the vibrational frequency calculations for this configurations of some isotopomers of butadiene- 1,3 are given. In addition, in the light of the theoretical results obtained and new experimental evidence, the assignment of certain out-of-plane normal modes of the anti-form of C₄D₆ is also discussed.     

Noise induced transitions due to external additive noise

The stationary Fokker-Planck equation in the two-dimensional case is solved locally using an antisymmetric tensor which transforms the problem into the potential case. Several examples are discussed which show that even additive external noise influences the extremal behaviour of the stochastic potential.     

Thermochemical properties of the HSO radical

Thermochemical properties of the HSO radical in the ideal gas state from 0 to 3000 K were calculated in the harmonic-oscillator, rigid-rotor approximation using recent spectroscopic data for the vibrational frequencies and heat of formation, and theoretical estimates of the molecular geometry.