A new copper(
ii
) complex (
I
) was obtained by the reaction of a sterically crowded 2,4-di-(
tert
-butyl)-9-chloro-benzo5,61,4oxazine2,3-
b
phenoxazine bridging ligand with Cu(
ii
) ...hexafluoroacetylacetonate. Compound
I
is a quasi-one-dimensional complex in which the Cu(hfac)
2
moieties are co-crystallized with the triphenodioxazine molecules through only weak Cu N short intermolecular interactions (the Cu N distances are 2.732 and 2.752 Å). The magnetic AC susceptibility data show that in spite of the absence of zero-field splitting in the Cu(
ii
) ion with
S
= 1/2, the compound demonstrates a slow magnetic relaxation behaviour at a weak applied magnetic field (
H
DC
= 500 Oe). The EPR spectra and DC magnetic measurements show the strong axial anisotropy of the g-tensor. The temperature dependence of the relaxation time is well described by the combination of one-phonon direct and two-phonon Raman processes.
A new copper(
ii
) complex (
I
) was obtained by the reaction of a sterically crowded 2,4-di-(
tert
-butyl)-9-chloro-benzo5,61,4oxazine2,3-
b
phenoxazine bridging ligand with Cu(
ii
) hexafluoroacetylacetonate.
Two new copper( ii ) complexes have been obtained by the reaction of sterically crowded triphenodioxazine ligands with Cu( ii ) hexafluoroacetylacetonate. Compound 1 is a co-crystal of Cu(hfac) 2 ...moieties and triphenodioxazine molecules within a quasi-one-dimensional crystal structure with only weak Cu⋯N short intermolecular interactions (Cu⋯N distances are equal to 2.69(1) and 2.75(1) Å). In contrast, complex 2 has a binuclear structure with two Cu(hfac) 2 units bridged through triphenodioxazine ligand with the covalent Cu–N bond length of 2.335(2) Å. The magnetic AC susceptibility data show that in spite of the absence of zero-field splitting in the Cu( ii ) ion having the ground state with spin S = 1/2, both compounds demonstrate slow magnetic relaxation at the applied magnetic field. For a quasi-one-dimensional complex 1, the optimal field for observing slow magnetic relaxation is 400 Oe, while for the binuclear complex it is 2500 Oe. The observed temperature dependence of the relaxation time in 1 is well described by the combination of Raman and direct mechanisms of relaxation, while for complex 2 the inclusion of Raman mechanism and quantum tunneling of magnetization is required to describe the relaxation behavior.
The paper is devoted to the topical issue of the formation of a variation method for calculating the accuracy of metal cutting systems. The current state of the basic variation method for calculating ...the geometric accuracy of metal cutting machines is determined. A transition from considering the geometric accuracy of only the metal cutting machine to considering the accuracy of the metal cutting system is made, which includes the metal cutting tool. The proposed directions for the development of the method are recommended to be divided into groups according to the criterion of linearized and non-linear formulation when building accuracy balances. The solution of the problem posed in the paper serves as a methodological basis for work on normalization and compensation of geometrical errors of machine tools, including the creation of the foundations of standards for the accuracy of metal-cutting machines and tools. This work is useful for scientists engaged in the study of the geometric accuracy of processing on metal-cutting machines, as well as the normalization and compensation of the geometric errors of machines.
The actual problem of modeling the influence of geometric errors of vertical milling machines on the accuracy of machined surfaces is considered in the paper. For the first time, a mathematical model ...of the accuracy of vertical milling machines is presented when processing a complex of keyway surfaces. The model was developed on the basis of a variational method for calculating the accuracy of metal-cutting systems, which is a development of the well-known variational method for calculating the accuracy of machine tools. The results of modeling the influence of geometrical errors of vertical milling machines on the accuracy of the machined surfaces of the keyway are given. Directions for further research of milling accuracy modeling with variable values of machine tool geometries are proposed. The work is useful for researchers engaged in research of the accuracy of technological equipment.
An approach is developed to analyze the results of the industrial enterprise in terms of achieving quality goals. The results of approbation of the developed approach are presented on the example of ...ZAO NPP 'ANA' (St. Petersburg). Based on the mathematical models created earlier by the authors, stability conditions are obtained depending on the values of the parameters of the enterprise quality management system, which enables to solve the problems of managing the state of this system as a subsystem of general management. For the study, the following were used: apparatus of the automatic control theory, Data Mining methodology, and elements of a Balanced Scorecard.
Zinc(II) complexes
2
,
3
, and
5
with redox-amphoteric
o
-indophenol ligands were prepared. The molecular structures of tetracoordinate complex
2
and hexacoordinate complex
3
were determined by ...single-crystal X-ray diffraction. The antioxidant properties of indophenols and their complexes were studied by cyclic voltammetry (CVA) and EPR spectroscopy. Complexation of indophenols increases the oxidation potentials by more than 0.84 V and leads to the formation of stable metal-containing radicals.
A series of new derivatives comprising heteropentacyclic 12
H
-quinoxalino2,3-
b
-phenoxazine (QOPO) system and functionalized with arylamide anchoring groups was synthesized. Their photostability as ...well as the spectral, luminescent, electrochemical, and optoelectronic properties were studied both in composites prepared by adsorption of QOPO onto the TiO
2
surface and in solution. Attachment of the amide anchoring groups to the QOPO core provides high adsorption of the compounds and the onset of photovoltaic properties that were not observed in the unfunctionalized precursors. However, these groups do not provide efficient injection of excited electrons into the conduction band of the semiconductor. According to B3LYP/6-311++G(d,p) density functional calculations of the model nanoclusters QOPO/(TiO
2
)
10
, efficient electron injection and, as a consequence, high photovoltaic conversion efficiency of dye-sensitized solar cells require delocalization of the LUMO of the QOPO/TiO
2
system over both structural fragments. Relevant anchoring groups are proposed.
A comparative analysis is provided for turning caprolon using replaceable polyhedral plates made from different materials, and in fact made of tungsten-cobalt alloy VK8 and ceramic material, i.e., ...tungsten-free hard alloy KNT60. It is established by experiment that for machining caprolon workpieces it is expedient to use replaceable cutting tools made from ceramic materials KNT60, which makes it possible to expand the range of tools used and improve turning efficiency as a whole.
The relevance of studying product quality control as based on optimization of process input values parameters is shown. The paper explores the tolerance synthesis method of technological process ...input parameters based on regression dependences. Electrolytic chromium plating process simulation has been performed enabling to optimize input parameter tolerances and upgrade process equipment. As a result of the modernization the galvanic bathtubs were outfitted for control parameters of the electrolyte, heating of the electrolyte. The modernization of electrolytic chromium plating process allowed finding of values of input parameters being within the required limits and providing for the quality of the products.
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