Immunoenzyme assay of nonylphenol: study of selectivity and detection of alkylphenolic non-ionic surfactants in water samples

Immunoenzyme assay (ELISA) is proposed and characterized for determination of alkylphenol ethoxylates, a primary class of manufactured non-ionic surfactants. The assay is based on the obtained polyclonal antibodies against nonylphenol (NP), the main stable intermediate of the decomposition of nonylphenol ethoxylates. A mixture of non-modified branched isomers of NP was applied as hapten coupled to protein carriers by Mannich reaction with the use of formaldehyde. The proposed ELISA format is based on immobilized NP-(soybean trypsin inhibitor) conjugate as a competitor of antigen molecules contained in the tested sample for binding with specific antibodies indirectly labeled via an anti-species immunoperoxidase conjugate. The developed ELISA allows to reveal NP with the limit of detection about 10 ng ml⁻¹ and NP-related compounds such as octylphenol, alkylphenoletoxylates, alkylphenolcarboxylates and their halogenated derivatives. The ELISA was applied for assaying polluted water samples, namely influents and effluents from different wastewater treatment plants (WWTP) and tap water. ELISA and chromatographic data demonstrate good correlation (r = 0.94), while ELISA gives higher values. Due to endocrine disrupting and other toxic activities of some metabolites of alkylphenolic non-ionic surfactants, the developed assay may be effectively used in ecological monitoring and sanitary control.     

Detection of intermediates in grignard reaction on the magnesium surface

Benzyl radicals and ion-radical pairs have been detected on a magnesium surface by electron spin resonance (ESR) spectroscopy during benzyl halide reactions with magnesium at low temperatures. The ratio of these intermediates depends on the carbon-halogen bond energy in the starting benzyl halide, the nature of the magnesium surface and the degree of magnesium aggregation. Polymagnesiumbenzyl chlorides were formed in small amounts and only monomagnesium organic compounds were formed from benzyl bromide and benzyl iodide.     

A Radon–Nikodým type theorem for orthosymmetric bilinear operators

A Radon–Nikodym type theorem for positive orthosymmetric bilinear operators is proved. The main tools are based upon homogeneous functional calculus on vector lattices and the concept of square of vector lattice.     

1-Substituted 5-thiotetrazoles as novel capping agents for stabilization of gold nanoparticles

Stable and nearly monodispersed gold nanoparticles with sizes of 2.8–4.7 nm are easily prepared by the reduction of tetrachloroaurate salts in a toluene-water system in the presence of 1-R-5-thiotetrazoles (R = Et, t-Bu, 1-adamatyl). The prepared gold nanoparticles were characterized by TEM, XRD, UV–Vis, FTIR and TGA.     

Luminescence of polymorph crystalline and glassy SiO2, GeO2: A short review

Studies of SiO₂ and GeO₂ crystals with α-quartz and rutile structures were performed during last two decades. The goal of such studies was comparison of properties with those of glassy modifications of these crystals. Luminescence of oxygen deficient centers in these glassy materials was found to resemble the luminescence of the rutile-type modification rather than α-quartz modification. In α-quartz, similar luminescence centers appear after damaging irradiation by electron beam at low temperatures (<60 K) or at ambient temperatures after gamma or neutron irradiation.     

On the distribution of Farey fractions and hyperbolic lattice points

We derive an asymptotic formula for the number of pairs of consecutive fractions a0=q0 and a=q in the Farey sequence of order Q such that a=q; q=Q; and (Q - q0)=q lie each in prescribed subintervals of the interval [0; 1]. We deduce the leading term in the asymptotic formula for `the hyperbolic lattice point problem" for the modular group PSL(2; Z ), the number of images of a given point under the action of the group in a given circle in the hyperbolic plane.     

Volt-Watt Sensitivity of Semimetal BiSb Film Thermocouple Sensors in the 8 mm Wavelength Range

The paper considers the experimental and analytical data on volt-watt characteristics of metal-semimetal BiSb film point contacts in 8 millimeter wavelength range. Analytical expressions have been obtained for the volt-watt sensitivity and the resistance of the metal-semimetal BiSb film point contacts. A thermoelectric millimeter wave range detector has been designed on the basis of the sensors; the performance is illustrated by experimentally determined volt-watt relations.     

Propagation of Elastic Waves in a Gas-Filled Poroelastic Medium: The Influence of the Boundary Conditions

We consider the propagation of elastic waves in gas-filled porous media at small but non-zero values of Knudsen numbers \( {\text{Kn}} \), where \( {\text{Kn}} = \lambda /l \), \( \lambda \) is the mean free path of gas molecules; \( l \) is the characteristic size of inclusion (the so-called slip regime). In this case, it is possible to apply the classic equations of hydrodynamics with modified boundary conditions at solid walls. We have assumed that the gas molecules distribution function is satisfied at the modified Maxwell boundary conditions (Struchtrup 2013; Mohammadzadeh and Struchtrup 2015). We have obtained the expressions for drag and added mass coefficients for the Biot equations of poroelasticity for a system of randomly oriented gas-filled cylindrical capillaries. Our calculations have shown that the drag and added mass coefficients depend considerably on the Knudsen number and the properties of the surface. The influence of the interfacial slip effect on the velocities of the compressional wave of the first kind and shear wave is small, but the velocity and attenuation of the compressional wave of the second kind are considerably influenced by this effect. The results obtained show the fundamental possibility of the determination of the accommodation coefficient by measuring the velocity of the compressional wave of the second kind for different values of the Knudsen number.