This paper discusses the numerical implementation of the mathematical model of the hydrodynamic process in the computational domain with an “extended geometry,” when its characteristic dimensions in ...the horizontal direction significantly exceed the vertical dimension. This is the typical property of a shallow water body or coastal system, which requires the development of specialized methods for solving the problems that arise in the process of discretizing grid equations. The explicit-implicit scheme has proved itself effective in solving the problem of transport in a shallow water body. The transition between time layers can be considered as an iterative process for solving the problem of diffusion-convection to settle. This idea forms the base for the formation of a preconditioner in the proposed method for solving grid equations obtained by approximating hydrodynamic problems in areas with extended geometry. A numerical experiment is carried out with the developed software module, which makes it possible to estimate the norm of the residual vector obtained by solving the grid equations of the pressure calculation problem based on the modified alternating triangular method (MATM) and the method for solving grid equations with a tridiagonal preconditioner, taking into account the hydrostatic approximation. According to the specifics of the developed method, it is effective in solving problems of aquatic ecology in the case of the computational domain, when its horizontal dimensions significantly exceed the vertical dimensions.
2-R-4,4-Bis(trifluoromethyl)benzo
f
1,3,2dioxaphosphepin-5-ones containing an endocyclic carbonyl group, when stored or slightly heated, undergo spontaneous intramolecular cyclization into P
+
–C–O
–
...-bipolar ions containing benzoxaphosphole and oxaphosphethane rings fused along the P–C bond. These ions further dimerize into carbaphosphatrane derivatives with a pentacoordinate phosphorus atom, where the P–C bond is incorporated simultaneously into four-, five-, and six-membered rings. Hydrolysis of the carbaphosphtranes leads to the formation of benzo
d
1,2oxaphosphole derivatives. The structure of one of the carbaphosphatranes, as well as one of the benzo
d
1,2oxaphospholes has been proved by X-ray diffraction analysis. Carbon substituents in the carbaphosphatrane occupy apical positions, whereas the more electronegative oxygen atoms are in equatorial positions.
The reaction of alkyl 3-bromo-3-nitroacrylates with substituted phenylhydrazines and hydrazides of aromatic acids proceeds through the formation of
aza
-Michael adducts. Their subsequent ...dehydrohalogenation with Et
3
N affords
N
′-substituted hydrazones of alkyl 3-nitropyruvates. A one-pot synthesis of these compounds was developed. The synthesized hydrazones have a
Z
configuration, which was confirmed by
1
H NMR spectroscopy and X-ray diffraction.
The first representative of the specific RSSR isomer of 14-membered tetrakisphosphine has been obtained instead of the RRRR/SSSS isomer predicted according to the empirical rule formulated recently. ...The geometry of the obtained 14-P
N
is preorganized for the dicopper complex formation with the unique coordination mode in the row of P
N
corands.
Fluoroquinolone antibiotics (norfloxacin, ciprofloxacin, and moxifloxacin) modified at the piperazine ring by sterically hindered phenolic moieties were synthesized and evaluated for antibacterial ...activity. It was found that this modification can lead to an increase in the antibacterial activity against Gram-positive strains of the bacteria
Staphylococcus aureus
ATCC 29213 and
St. epidermis
compared to parent fluoroquinolones. Modified compounds additionally containing the phosphonate moiety exhibit the highest activity against
St. epidermis
. Moxifloxacin containing the 3,5-di-
tert
-butyl-4-hydroxybenzyl moiety is more active against
Escherichia coli
ATCC 25922 than all the characterized unmodified fluoroquinolones. Ciprofloxacin derivatives bearing sterically hindered phenolic moieties exhibited high activity against clinical isolates of Gram-negative bacteria.
The paper presents a three-dimensional hydrodynamic mathematical model that takes into account the processes of salt and heat transport in the Sea of Azov and makes it possible to obtain ...three-dimensional fields of water flow velocities, pressure, sea water density, salinity, and temperature. The model includes the Navier–Stokes equations of motion, the continuity equation in the case of variable density, and the equations of heat and salt transport. Boundary and initial conditions are specified. The diffusion–convection–reaction equation is approximated in time using weighted schemes. Approximation in spatial variables in the problem of determining the velocity field of the aquatic environment was performed by the balance method, taking into account the filling factors of the control regions. The initial distributions of salinity and temperature, which have a sufficient degree of smoothness at the points of setting their values, was performed using the Laplace equation. Maps of salinity and temperature of the Sea of Azov were obtained by interpolation and superimposing the boundaries of the region. Stationary regimes of heat and salt transfer have been studied. Based on the results of monitoring the water area, three-dimensional mathematical models of the movement of the aquatic environment were built, designed to predict possible scenarios for the development of the Azov Sea ecosystem, making it possible to study how anaerobic contamination areas emerge and take timely measures to localize them. To refine the input data of the mathematical model, an algorithm based on the Kalman filter was developed and implemented, which made it possible to obtain the minimum variance of the unbiased estimate of the state of the dynamic system. The elements of the software package are listed, making it possible to simulate hydrodynamic processes in shallow water bodies with complex spatial structures of currents with the transport of salts and heat.
The first representatives of the tetranuclear gold(i) complexes of P,N-containing cyclophanes with two 1,5-diaza-3,7-diphosphacyclooctane rings incorporated into the macrocyclic core have been ...obtained. The complexation leads to a change in ligand conformations so that the diazadiphosphacyclooctane fragments of the complexes adopt twist-chair conformations, and two of the four gold(i) ions are located over and under the partially collapsed macrocyclic cavity. The complexes demonstrate moderate solid-state green emission.
N
-Benzylation of acylhydrazones of the hydroxybenzaldehyde series with 3,5-di-
tert
-butyl-4-hydroxybenzyl acetate was performed at room temperature in the absence of acid or base catalysts. ...Carboxamides do not react with 3,5-di-
tert
-butyl-4-hydroxybenzyl acetate under similar conditions. N-Benzylation of isoniazid and (diphenylphosphoryl)acetic acid hydrazones was shown to be an efficient method for the synthesis of new hybrid compounds containing moieties of biologically active acylhydrazones and sterically hindered phenols.
N
-Benzyl derivatives of isoniazid and (diphenylphosphoryl)acetic acid hydrazones containing a hydroxy group at the
ortho
position of the aromatic ring are formed as individual
E
isomers with respect to the C-N double bond.
A convenient two-stage synthesis of phosphorylated sterically hindered methylene quinones was developed. The first stage involved the reaction of phosphorous acids with a sterically hindered phenol ...to form the corresponding phosphonates, whose oxidation at the second stage gave the corresponding methylene quinones. The resulting stable phosphorylated sterically hindered methylene quinones were reacted with bisphosphines led to novel phosphorylated ylides. The composition and structure of the synthesized compounds were established by chemical, physical, and physicochemical methods (IR,
1
H and
31
P NMR, and elemental and X-ray diffraction analysis).
The structure of the products of anodic oxidation of triphenylphosphine in the presence of camphene carried out in acetonitrile with sodium perchlorate as supporting electrolyte has been studied. The ...major product, triphenylphosphine oxide, has been isolated from the solution in the form of cocrystals of free triphenylphosphine oxide and its complex with sodium perchlorate. The molecular structure of the cocrystals has been studied by X-ray diffraction analysis. Triphenylcamphenylphosphonium perchlorate, bornylacetamide, and a terpene compound with triphenylphosphonium and acetamide substituents in the cycle have been detected by NMR
13
C as the electrolysis side products.
PDF
