Surface properties of semiconductor analogs of CdB<Superscript>VI</Superscript> and their solid substitution solutions

The physicochemical (acidic-basic, adsorption, and electrophysical) surface properties of binary semiconductor analogs of CdB^VI (CdTe, CdSe, and CdS), and (CdTe)_x(CdSe)_1–x, and (CdTe)_x(CdS)_1–x solid substitution solutions were studied using modern methods and equipment. The nature of the active centers and the mechanisms of acidic-basic, adsorption (involving СО), and electronic interactions, interrelated tendencies in variation of the surface properties under study, and their correlations with the known bulk physicochemical properties were elucidated; the property–composition diagrams were constructed, which were used to reveal the most active adsorbents suggested for use as materials for СО (carbon monoxide) microimpurity sensors.     

Neutron diffraction investigation of structural and magnetic states of lithium-doped antiferromagnet NiO

The elastic neutron scattering in polycrystalline samples of the (Ni_1−x Li_x)O solid solutions (x<0.1) is investigated by neutron diffraction technique. It is shown for the first time that the doping of nickel monoxide by lithium is accompanied by the formation of vacancies in the anionic sublattice, and the vacancy concentration is equal to the lithium content in the solid solution. The neutral lithium atoms are randomly arranged over sites of the cationic sublattice with possible spatial polarization of a valence electron toward an oxygen vacancy. In the composition range studied, the diamagnetic dilution of nickel monoxide by lithium turns out to be magnetically similar to the dilution with magnesium. In both cases, the Néel temperature and the mean magnetic moment per atom linearly decrease with an increase in concentration of the diamagnetic dopant.     

Investigation of the Structure and Functional Properties of Diamond-Like Coatings Obtained by Physical Vapor Deposition

Diamond-like coatings with a total thickness of ~0.6 μm are obtained by physical vapor deposition with plasma separation and a pulsed carbon arc source with a cooled cathode and laser arc ignition; the substrates are titanium alloy (VT4), stainless steel (12Cr18N10T), and copper (M1). Scanning electron microscopy and profilometry are used to study the coatings surface and structure. The composition of the coatings and the fraction of sp³ bonds are studied using Raman spectroscopy. A wide peak in the 1580 cm^-1 region is observed characteristic of diamond-like coatings. The coatings have a dense, nonporous structure. The tribological properties of the coatings are evaluated by the ball-on-disk method using a friction pair with WC and technical diamond. The strength characteristics are determined using linear scratch testing and nanoindentation measurements. The strength characteristics of the coatings vary and depend on the substrate materials. The friction coefficient of a diamond-like coating on VT4 alloy is ~0.1 in a friction pair with WC and ~0.01 with technical diamond.     

Magnetocaloric effect in (La<Subscript>0.6</Subscript>Ca<Subscript>0.4</Subscript>)<Subscript>0.9</Subscript>Mn<Subscript>1.1</Subscript>O<Subscript>3</Subscript>

The results of investigations of the magnetization, susceptibility, and magnetic-field-induced changes in the entropy of polycrystalline manganite (La_0.6Ca_0.4)_0.9Mn_1.1O₃ near the magnetic phase transition have been presented. Magnetic measurements have been carried out at temperatures in the range from 210 to 310 K in magnetic fields of up to 9 T. The magnetocaloric effect has been revealed by measuring the magnetic-field dependences of magnetization. The magnitude of the magnetocaloric effect is compared with similar results obtained for other manganites.     

Wave propagation on a charged surface of a cylindrical liquid column surrounding a long porous core

A mathematical model of wave propagation and instability on a charged surface of an infinite cylindrical column of a conducting fluid, surrounding a coaxial infinite porous core, is formulated and studied. The conditions are found under which the disturbances of the liquid column become unstable and result in its fragmentation into a chain of connected droplets. It is shown that the length of the droplets decreases with increase in the electric field.     

On the Acid–Base State of the Surface of Semiconductor Components of the ZnSe–CdS System Exposed to Different Media

Using the methods of hydrolytic adsorption, mechanochemistry, and nonaqueous conductometric titration, the acid–base properties of the surfaces of binary semiconductors and solid solutions of the ZnSe?CdS system are studied. The nature of acid sites, and the extent, character, and mechanism of the surface (absorption) interaction are established. The interrelationships in the changes of the acid–base and bulk physical properties upon changing the chemical composition are determined, which make it possible to draw conclusions that are fundamentally important in scientific and practical aspects.     

Rheological and relaxation properties of MQ copolymers

The rheological properties of MQ copolymer melts are investigated under steady-state shear flow and dynamic oscillatory shear within a wide temperature range. The MQ copolymers are highly branched polycyclic compounds (densely crosslinked nanosized networks) incapable of further intermolecular interactions. The samples have identical chemical compositions, but their detailed molecular structures are different. The polymers under consideration show Newtonian behavior in a wide shear-stress range. The values of viscosity vary considerably with the molecular structure of the copolymers. The generalized frequency dependence of complex dynamic modulus components is constructed with the use of the temperature-frequency superposition method. In a first approximation, the viscoelastic behavior of the materials is satisfactorily described by the Maxwell model with a single relaxation time. In this respect, the studied materials are similar to micellar colloids. The relaxation spectra of the copolymers distinguished by narrow distributions are calculated.     

Sorption of azo dyes from aqueous solutions by tetradodecyloxybenzylcalix[4]resorcinarene derivatives

Four water-insoluble tetradodecyloxybenzylcalix[4]resorcinarenes with various functional groups at the upper macrocycle rim (unsubstituted calix[4]resorcinarene 1, carboxylic acid derivative 2, ethyl ester derivative 3 and aminoethylamide derivative 4) were synthesized and tested as sorbents for water-soluble azo dyes methyl orange (MO), acid orange 5 (AO 5) and congo red (CR) by solid–liquid extraction method without background electrolyte. It was observed that the sorption of azo dyes reaches 99% for sorbent 4, which is partial protonated in contact with water and becomes able to electrostatic interactions with the dyes. It was demonstrates that calixresorcinarene 4 has the excellent sorption capacity for AO5 (130.5?mg dye per g of sorbent) due to effective calixresorcinarene—dye association in equal molar ratio mode.     

Molecular and crystal structure of 2,3-dimethyl-5-(2′-methylprop-1′-enyl)-6-(morpholyl-4′-carbonyl)-cyclohex-3-en-1-carboxylic acid

An X-ray structural examination is carried out for 2,3-dimethyl-5-(2′-methylprop-1′-enyl)-6-(morpholyl-4′-carbonyl)-cyclohex-3-en-1-carboxlic acid that is one of the products of the Diels-Alder reaction of an acyclic monoterpene alloocimene with maleic and citraconic anhydrides followed by the ring opening of adducts with morpholine to corresponding amides. The crystals are triclinic; a = 10.619(1) ?, b = 12.784(2) ?, c = 14.328(2) ?; α = 65.752(1)°, β = 87.932(1)°, γ = 78.120(1)°; V = 1733.0(3) ?³, P-1 space group, Z = 4 (two independent molecules). In both molecules, the anti-conformation of the carboxylic group is observed, the conformation being stabilized by an intramolecular hydrogen bond involving the carboxylic hydrogen atom and ketonic oxygen.