d‐Secoestrone derivatives. VI. 17β‐Benzyl‐17α‐hydroxy‐3‐methoxyestra‐1,3,5(10)‐trien‐16‐one

The title mol­ecule, C₂₆H₃₀O₃, shows a novel chemical rearrangement of the substituents at position 17, i.e. an α‐­orientation of the hydroxy group and a β‐orientation of the bulky benzyl moiety. The packing arrangement consists of coils formed by O2?O3 hydrogen bonds along the c axis. The compound shows complete loss of oestrogenic activity, and neither does it exhibit an antagonistic effect.     

Synthesis and Investigation of Geometrical Isomerism of Trinitro(aminoacidato)amminecobaltate(III) Complex Salts

Synthesis of a new class of coordination compounds of cobalt(III) with amino acids (glycine, alanine, α-amino-butyric acid and norvaline), i.e., trinitro(aminoacidato)-amminecobaltate(III) salts, M[CoNH₃Am(NO₂)₃], is described. The synthesis consists in the action of amino acid alkali salts on the Erdmann salt or peripheral isomer of trinitrotriamminecobalt(III). The same compounds were also obtained by direct synthesis, i.e., by hydrogen peroxide oxidation of cobalt(II) to cobalt(III) in the presence of the corresponding ligands. The peripheral configuration of the complexes obtained was determined by chemical and physical methods (electronic and PMR spectroscopy). The compounds are intermediates formed in obtaining of dinitrobis(aminoacidato)cobaltate(III) salts by the reaction of amino acids with the Erdmann salt or peripheral isomer of trinitrotriamminecobalt(III).     

Establishment of traceability of ammonium nitrogen determination in wastewater

A case study is presented for the establishment of traceability for ammonium nitrogen determination in wastewater in a routine laboratory in order to fulfil the requirements of ISO/IEC standard 17025. The necessary relevant information was obtained from the method validation data, the quality control data and equipment calibration certificates. The method of measurement is described together with the measurement equation, selected traceable reference standards and the associated measurement uncertainty. The major sources of uncertainty of the result of measurement were identified and the combined uncertainty was calculated. Identification of the main uncertainty sources represents the basis for target operations for reducing the measurement uncertainty of this determination.     

New relationship of displacement signal at quadrant photodiode: Control signal analysis and simulation of a laser tracker

New relationship of displacement signal using opposite sectors on a quadrant photodiode is derived. Standard and new displacement signals are analyzed in details. Through MATLAB^® laser tracking simulation models, based on common and suggested approaches, detailed analysis is performed, and it is shown that better results for the new relationship signal processing are obtained. Within new relationship of displacement signal, the sensitivity of the system to the displacement of the spot increases and, hence, provides better accuracy in positioning up to 30%.     

Highly resolved fluid flows: "liquid plasmas" at the kinetic level

Fluid flow around an obstacle was observed at the kinetic (individual particle) level using "complex (dusty) plasmas" in their liquid state. These "liquid plasmas" have bulk properties similar to water (e.g., viscosity), and a comparison in terms of similarity parameters suggests that they can provide a unique tool to model classical fluids. This allows us to study "nanofluidics" at the most elementary-the particle-level, including the transition from fluid behavior to purely kinetic transport. In this (first) experimental investigation we describe the kinetic flow topology, discuss our observations in terms of fluid theories, and follow this up with numerical simulations.     

Stereoelectronic control in the oxidation of gem-disulphides

The first example of stereospecific oxidation in the gem-disulphide series is reported; chemical, spectral, and X-ray evidence indicated the stereoelectronic discrimination between two modes of approach of electrophile in the conversion to meso-2,2-bis(methylsulphinyl)-1,3-diphenylpropane ($\text{2}$).     

Electric and electrochemical properties of solid LiH2PO4

Electrical and electrochemical properties of solid LiH₂PO₄ conductor were investigated in the temperature range from room temperature to 373 K. It was found that high conductivity throughout the temperature range, with activation energy 17.23 kJ/mol, originates from the movement of hydrogen ions (protons). The movement of protons in the correlation with phosphate groups rotation was considered. The slopes of Tafel lines and exchange current densities both for cathodic hydrogen and anodic oxygen evolution were determined (by means of usual electrochemical kinetic methods) at various temperatures. The energy of activation at the equilibrium potentials both for the cathodic and the anodic processes have been assessed to be 17.23 kJ/mol (0.18 eV) and 2.9 kJ/mol (0.03 eV), respectively.