Flow capacity of the capillary copper tube as its figure of merit

The use of capillary copper tube is popular for manufacturing of gauges and evaporators of refrigeration units. Its main feature is a small inner diameter (no more than 0.9 mm), which makes it difficult to measure it along the whole length of the tube, thus, indirect test methods are used for its determination. Main problem in manufacturing of quality tubes is providing the necessary flow capacity. This article features these under-investigated issues by determining correlation between technological parameters and figures of merit of the capillary copper tubes. Specifically, it was found how flow capacity changes by the influence of such parameters as heat treatment (annealing), tube channel diameter and length of the treated product. © 2020 Published under licence by IOP Publishing Ltd.The work has been performed with financial support of the Government of the Russian Federation, Act No. 211, Contract No. 02.A03.21.0006

Influence of Annealing on the Roughness of a Surface of Copper Pipes

Roughness measurements of the inner surface of copper pipes along the drawing passes were performed in two versions: before and after annealing. It was revealed that the roughness increases after recrystallization annealing. This phenomenon is explained by the nucleation and growth of new grains having their own surface shape. With subsequent drawing, this surface shape is smoothed out by plastic deformation.Выполнены измерения шероховатости внутренней поверхности медных труб по проходам волочения в двух вариантах: до и после отжига. Выявлено, что шероховатость повышается после проведения рекристаллизационного отжига. Такое явление объяснено зарождением и ростом новых зерен, имеющих свою форму поверхности. При последующем волочении эта форма поверхности разглаживается пластической деформацией

Supramolecular nanoscale systems based on amphiphilic tetramethylensulfonatocalix[4]resorcinarenes and cationic polyelectrolyte with controlled guest molecule binding

© 2016 Informa UK Limited, trading as Taylor & Francis GroupThe water-soluble tetramethylensulfonatocalix[4]resorcinarene with methyl (C1) and pentyl (C5) substitutes on the lower rim forms colloid nanoscale aggregates with poly(diallyldimethylammonium chloride) (PDDA) in aqueous solutions. The size and stability of nanoparticles depend on concentrations of the components and their ratio in the ‘calixarene-polymer’ system. Ternary supramolecular complexes «polymer–macrocycle–guest molecule L-tryptophan (Trp) in conditions of spontaneous pH (3.80 and 4.78 for C1-PDDA and C5-PDDA systems, respectively) in an aqueous solution and in phosphate buffer (pH 7) were investigated by fluorescence method. The addition of the third component – PDDA – to the «non-aggregated C1–Trp» associates leads to the release of Trp in all studied conditions. The possibility of the «binding–release» process of L-tryptophan in «C5–Trp» associates after PDDA addition in the ternary complex is achieved and controlled by the structure of the macrocyclic self-associates and pH conditions

One-step synthesis of gold colloids using amidoaminocalix[4]resorcinarenes as reducing and stabilizing agents. Investigation of naproxen binding

© 2017 Elsevier B.V.Amido(dimethylamino) calix[4]resorcinarenes with different substituents on the lower rim (-CH3 (С1), −C5H11 (C5), −C11H23 (C11)) both as reducing and stabilizing agent in an aqueous solution were used for the fabrication of stable gold colloids. Gold colloids are characterized by spectrophotometry, FTIR − spectroscopy, transmission electron microscopy, dynamic light scattering. It is found that increase of the macrocycle's concentration towards HAuCl4 concentration during the synthesis leads to the decrease in the size of formed particles. It is shown that the size of gold nanoparticles (AuNPs) decreases with the increase of the hydrophobicity of the substituents on the macrocycles lower rim (C1@Au − 4–14 nm, C5@Au - 10–11 nm, C11@Au − 7–8 nm). The monolayer packing of the macrocycle molecules on the surface of the metal particle for C1@Au and bilayer − for C5@Au and C11@Au, providing both the stabilization of AuNPs and their solubility in water, are proposed. Temperature and pH variation during the synthesis showed that the optimal synthesis conditions for all kinds of particles C1@Au, C5@Au, C11@Au are spontaneous installed during the synthesis pH (for C1@Au − pH 8.10, C5@Au − pH 8.56, C11@Au − pH 8.63) and the synthesis temperature of the 25 °C. High binding fraction of drug substrate naproxen on the surface of AuNPs modified by C5 and C11 macrocyclic aggregates due to the ordering of the macrocycles on the particle surface and enhancing their receptor ability towards naproxen is defined by fluorescence method

Nanoassociates of amphiphilic carboxy-calixresorcinarene and cetylpyridinuim chloride: The search of optimal macrocycle/surfactant molar ratio

© 2018 Elsevier B.V. Here we present the supramolecular surfactant-macrocycle system which properties are independent on system composition in the wide range of components concentrations. The study of the interaction of octacarboxy-tetra(p-phenylene-oxy-pentyl)calixresorcinarene (C5R) and cetylpyridinuim chloride (CPC) in mixed aqueous solutions were performed by dynamic light scattering and electrophoretic methods,1H and FT-PGSE NMR methods, absorption and fluorescence spectroscopy, and TEM. The variation of CPC/C5R molar ratio from 30/1 to 10/1 leads to the formation of nanoassociates with similar composition, size, surface potential value, and improved (in compare with CPC) solubilizing properties. The preparation of mixed supramolecular systems which properties are independent on system composition in the wide range of components concentrations is an elegant example of the producing of colloidal materials with the required morphology and properties

Supramolecular nanoscale systems based on amphiphilic tetramethylensulfonatocalix[4]resorcinarenes and cationic polyelectrolyte with controlled guest molecule binding

© 2016 Informa UK Limited, trading as Taylor & Francis Group.The water-soluble tetramethylensulfonatocalix[4]resorcinarene with methyl (C1) and pentyl (C5) substitutes on the lower rim forms colloid nanoscale aggregates with poly(diallyldimethylammonium chloride) (PDDA) in aqueous solutions. The size and stability of nanoparticles depend on concentrations of the components and their ratio in the ‘calixarene-polymer’ system. Ternary supramolecular complexes «polymer–macrocycle–guest molecule L-tryptophan (Trp) in conditions of spontaneous pH (3.80 and 4.78 for C1-PDDA and C5-PDDA systems, respectively) in an aqueous solution and in phosphate buffer (pH 7) were investigated by fluorescence method. The addition of the third component–PDDA–to the «non-aggregated C1–Trp» associates leads to the release of Trp in all studied conditions. The possibility of the «binding–release» process of L-tryptophan in «C5–Trp» associates after PDDA addition in the ternary complex is achieved and controlled by the structure of the macrocyclic self-associates and pH conditions

The supramolecular approach to the phase transfer of carboxylic calixresorcinarene-capped silver nanoparticles

© 2017 Elsevier B.V.The octacarboxylic derivative of tetrapentylcalix[4]resorcinarene (1) was used as stabilizer for preparation of silver nanoparticles (AgNPs) hydrosol. The calixresorcinarene-capped nanoparticles Ag@1 are stably dispersed in an aqueous colloid solution and have an average diameter of 4–6 nm (TEM). The interaction of the macrocycle 1, possessed the receptor properties, with the cationic surfactant cetyltrimetylammonium bromide (CTAB) leads to the hydrophobization of AgNPs hydrosol. It was shown, that macrocycle 1 in its individual solution forms the hydrophobic associate with 8 mol of CTAB (1H NMR, 2D NOESY). Various and complicated influence of CTAB/macrocycle molar ratio on the hydrophobization of AgNPs and their transfer into organic phase was demonstrated. The initial Ag@1 and modified Ag@1-CTAB were characterized by UV-vis and FTIR spectroscopy, DLS, and TG/DSC methods It was shown that the efficiency of water/organic phase transfer depends on the macrocycle/surfactant molar ratio. The presented supramolecular approach can be useful to form the ordered nanostructures through supramolecular modification and self-organization of hybrid metal nanoparticles

Calixresorcinarene-capped silver nanoparticles as new supramolecular hybrid nanocontainers

© 2017 The synthesis of small (2–3 nm) silver nanoparticles in the presence of new amidoaminocarboxylic tetrapentylcalix[4]resorcinarene and the binding of the antitumor drug Doxorubicin by a macrocycle in solution and on the surface of nanoparticles are described