Mendeleev Communications最新文献

Poly(vinyl alcohol) (PVA) was incorporated into the mesoporous structure of high-density polyethylene (HDPE) directly upon the tensile drawing of films via crazing in water–ethanol PVA solutions. The structure and thermophysical properties of the HDPE–PVA nanocomposites were explored by differential scanning calorimetry and X-ray analysis. PVA was found to exist in an amorphized state within the mesoporous structure of the HDPE host matrix since its crystallization is prevented by the spatial confinements.

Ni–P coatings, with their high microhardness (HV) and wear resistance, have been proposed as a viable alternative to hard chromium. However, wear testing experiments on electroless Ni–P coatings were conducted under a variety of conditions, including test equipment, load, substrate materials and counterface materials, resulting in unreliable comparative evaluations of experimental results. Therefore, this article presents an analysis of experimental research on Ni–P and Cr coatings, as well as a statistical analysis of the results obtained under similar conditions. The results of simultaneous wear tests on Ni–P and Cr coatings published from 1958 to 2022 were used for evaluation and comparative analysis. The relative wear of Ni–P versus hard Cr was calculated from experimental data and analyzed using statistical methods such as Tukey’s statistical methods, nonparametric and parametric statistics. This review found that the wear performance of electroless nickel coatings generally does not match that of hard chromium coatings. The results of this analysis indicate that: (i) Ni–P coating can be used as a protective and hardening coating; (ii) the wear resistance of the electroless Ni–P coating, being 1.9 ± 0.4 times less, does not reach the same level of wear resistance as that of hard Cr; (iii) there is a tendency for the wear resistance of Ni–P to gradually approach the wear resistance of Cr; (iv) the dependence of the wear rate on the phosphorus content of the Ni–P alloy indicates that the minimum possible wear rate is achieved at a P content of about 4–7 wt%. The search for effective alternatives to hard chromium plating is ongoing, and this review has identified several areas where effective engineering solutions could be found.

The effectiveness of the combined action of ultrasound and γ-radiation on Lactobacillus casei is studied. A superadditive death effect is shown, whose magnitude depends on dose levels, sequence of effects, and the presence of theraphthal (sodium salt of cobalt 4,5-octacarboxyphthalocyanine) as a sonosensitizer.

Addition of allylzinc to cyrene affords diastereomeric 4-allyl-6,8-dioxabicyclo[3.2.1]octan-4-ols. Opening of their 1,6-anhydro bridge with Ac₂O followed by selective deacetylation of the resulting tertiary and acetal acetates yields diastereomeric 2-acetoxymethyl-5-allyl-tetrahydro- pyran-5,6-diols whose oxidation by the action of DMSO–Ac₂O system is accompanied by etherification of tertiary hydroxy groups leading to methylthiomethoxy pyrone derivatives. The opening of 1,6-anhydro bridge in 4-allyl-6,8-dioxabicyclo[3.2.1]octan-4-ols with MeOH–HCl followed by oxidation with PCC gives individual (4S,6S)- 1-allyl-6-methoxy-2,5-dioxabicyclo[2.2.2]octan-3-one.

Water-soluble nanosized systems of aluminum phthalo- cyanine, which is a promising photosensitizer for photodynamic therapy and fluorescence diagnostics, were obtained by encapsulating it in biocompatible copolymers of N-vinylpyrrolidone with mono- and dimethacrylates. The physicochemical (water solubility, stability and size of nanoparticles) and photophysical (absorption and fluorescence) properties of the resulting nanoparticles in aqueous solution were determined. Quantum chemical modeling revealed the formation of coordination bonds between the Al atom of the dye and the oxygen atoms of all monomer units.

Reaction of [(coe)₂IrCl]₂ (coe = cyclooctene) with AgPF₆, arene (toluene, p-xylene, mesitylene), and diphenylacetylene, followed by counter anion exchange to BARF^–, gives cyclobutadiene iridium complexes [(C₄Ph₄)Ir(arene)]BARF in 10–22% yield. Replacement of toluene in [(C₄Ph₄)Ir(toluene)]BARF by various ligands (trimethyl-phosphite, 1,3,5-triaza-7-phosphaadamantane, tert-butyl isonitrile) provides access to the half-sandwich cyclobuta-diene iridium complexes [(C₄Ph₄)Ir(L)₃]BARF. Complex [(C₄Ph₄)Ir(toluene)]BARF in combination with [NBnEt₃]Cl catalyses the insertion reaction between phenyl diazoacetate and various amines.

Thiazolidin-4-ones functionalized at the position 5 and their heterocycle-annulated analogues were obtained based on the reaction of thioureas with dialkyl acetylenedicarboxylates. In most cases the reaction proceeds with high selectivity to form 2-iminothiazolidin-4-one-type products.

1-Alkylsulfanyl-4-X-2,3,5,6-tetrafluorobenzenes (X = CF₃, H; alkyl = Me, Bn, CHF₂) upon reactions with nitromethane in the presence of DBU undergo replacement of 2 or 3-positioned fluorine atoms by a nitromethyl group to afford the corresponding (nitromethyl)trifluoroarenes. The calculations of the transition states using the DFT method correctly predict the ratios of reaction products. In the cases of relative sulfones, only 2-positioned fluorine atom undergoes substitution; however, the sulfonyl group can also be displaced by a nitromethyl moiety.

A water-soluble cationic porphyrin containing N-methyl- pyridinium fragments and an indole residue, namely, 5-[4-(1-methylindol-2-yl)phenyl]-10,15,20-tris(1-methyl- pyridinium-3-yl)porphyrin triiodide, has been synthesized. The porphyrin forms sedimentation unstable complexes with low and high molecular weight nucleic acids. This ability to precipitate nucleic acids can be used in laboratory, clinical and research practice for isolating nucleic acids.

Pyrazoles bearing (2,3,5,6-tetrafluoropyridinyl)thio group were obtained from 3-aminopyrazoles. The reaction is performed by diazotization of starting amines followed by treatment of the intermediate diazonium salts with 2,3,5,6-tetrafluoropyridine-4-thiol and potassium carbonate. The method is best applied towards 4-substituted 3-aminopyrazoles.