Mixed halide complexes of lead. A comparison with theoretical predictions

Experimentally and theoretically derived formation constants of mixed lead halide complexes are compared at 25.0°C and one molar ionic strength. The formation constant of PbBrCl, ₁₁=79±10, is somewhat larger than the theoretical results, ₁₁=55, predicted using the formation constants of PbBr₂ and PbCl₂. The molar absorptivity of PbBrCl was observed to be intermediate in character between the molar absorptivities of PbBr₂ and PbCl₂. Determinations of the formation constants of PbBr₂Cl^– and PbBrCl₂ ^– are in reasonable agreement with the predictions based on the formation constants of PbBr₃ ^– and PbCl₃ ^–. Mixed ligand species dominated the complexation scheme of Pb(II) in our test media.     

Metallbindungsphänomene: Alkoholat-Aggregate als unmittelbare Teilnehmer an Eliminierungsreaktionen

In solvents of low polarity it is neither a monomolecular nor a dissociated alcoholal species which effects dehydrohalogenation of vic-dihaloalkanes and vic-dihalocycloalkanes but rather a dimeric, trimeric or tetrameric alcoholate aggregate. This behavior has important implications for the stereochemical outcome of such elimination reactions.     

Remarks on the set-valued integrals of Debreu and Aumann

Some recently obtained sufficient conditions for the weak compactness of subsets of L¹(m, X) are used to show that for functions whose values are compact, convex subsets of a Banach space the Debreu integral, when it exists, is the same as the Aumann integral. Here no assumption is made concerning the reflexivity of X. This result extends to functions whose values are weakly compact, convex subsets of Banach space.     

Search for ferromagnetic ordering in Pd doped wide band gap semiconductors GaN and ZnO

GaN and ZnO are possible candidates for dilute magnetic semiconductors with Curie temperatures above room temperature. Doping with transition metals like Co, Mn or Fe could be a simple way to create such systems. The perturbed angular correlation (PAC) probe ¹⁰⁰Pd/¹⁰⁰Rh is isoelectronic to cobalt and therefore a perfect tool to investigate the incorporation of transition metals into these compounds as well as the influence of other impurities on internal magnetic fields. The (0001) and (10 $\bar{1}$ 10) surfaces of ZnO single crystals, freestanding GaN films, and GaN thin films (6 μm) on sapphire substrates were recoil-implanted with the ¹⁰⁰Pd/¹⁰⁰Rh probe. The probe was produced using the fusion evaporation reaction ⁹²Zr(¹²C, 4n)¹⁰⁰Pd at a beam energy of 69 MeV. Subsequently, the incorporation of the probe was studied by PAC spectroscopy during an isochronal annealing program. First results without and with an applied external magnetic field are indicative of a strongly disturbed lattice vicinity of Pd impurities in both hosts. No signs of spontaneous ferromagnetic ordering were observed.     

Turbulence decay rate as a measure of flow dimensionality

The dimensionality of turbulence in fluid layers determines their properties. We study electromagnetically driven flows in finite-depth fluid layers and show that eddy viscosity, which appears as a result of three-dimensional motions, leads to increased bottom damping. The anomaly coefficient, which characterizes the deviation of damping from the one derived using a quasi-two-dimensional model, can be used as a measure of the flow dimensionality. Experiments in turbulent layers show that when the anomaly coefficient becomes high, the turbulent inverse energy cascade is suppressed. In the opposite limit turbulence can self-organize into a coherent flow.     

Rank metric codes and zeta functions

We define the rank metric zeta function of a code as a generating function of its normalized q-binomial moments. We show that, as in the Hamming case, the zeta function gives a generating function for the weight enumerators of rank metric codes. We further prove a functional equation and derive an upper bound for the minimum distance in terms of the reciprocal roots of the zeta function. Finally, we show invariance under suitable puncturing and shortening operators and study the distribution of zeroes of the zeta function for a family of codes.     

Practical High-Throughput Method to Screen Compounds for Anthelmintic Activity against Caenorhabditis elegans

In the present study, we established a practical and cost-effective high throughput screening assay, which relies on the measurement of the motility of Caenorhabditis elegans by infrared light-interference. Using this assay, we screened 14,400 small molecules from the “HitFinder” library (Maybridge), achieving a hit rate of 0.3%. We identified small molecules that reproducibly inhibited the motility of C. elegans (young adults) and assessed dose relationships for a subset of compounds. Future work will critically evaluate the potential of some of these hits as candidates for subsequent optimisation or repurposing as nematocides or nematostats. This high throughput screening assay has the advantage over many previous assays in that it is cost- and time-effective to carry out and achieves a markedly higher throughput (~10,000 compounds per week); therefore, it is suited to the screening of libraries of tens to hundreds of thousands of compounds for subsequent evaluation and development. The present phenotypic whole-worm assay should be readily adaptable to a range of socioeconomically important parasitic nematodes of humans and animals, depending on their dimensions and motility characteristics in vitro, for the discovery of new anthelmintic candidates. This focus is particularly important, given the widespread problems associated with drug resistance in many parasitic worms of livestock animals globally.     

High-spin isomers in Rn in the region of triple neutron core-excitations

The level scheme of ²¹²Rn has been extended to spins of ∼38?$\sim 38?$ and excitation energies of about 13 MeV using the ²⁰⁴Hg(¹³C, 5n)²¹²Rn reaction and γ-ray spectroscopy. Time correlated techniques have been used to obtain sensitivity to weak transitions and channel selectivity. The excitation energy of the 22⁺ core-excited isomer has been established at 6174 keV. Two isomers with τ=25(2) ns$\tau =25(2)\text{ns}$ and τ=12(2) ns$\tau =12(2)\text{ns}$ are identified at 12211 and 12548 keV, respectively. These are the highest-spin nuclear isomers now known, and are attributed to configurations involving triple neutron core-excitations coupled to the aligned valence protons. Semi-empirical shell-model calculations can account for most states observed, but with significant energy discrepancies for some configurations.