Two-Dimensional Water Quality Model for Unsteady Advection-Diffusion of Nonconservative Substances

A numerical model for calculation of advective-diffusive transport of nonconservative substances in two-dimensional environments was developed. The numerical method is based on the splitting-operator approach, in which the advection, the diffusion and the chemicallbiological kinetic processes are calculated separately in one time step. Special attention was paid to the advection operator, which introduces essential difficulty in many numerical methods, and to the linearized source term which, in many cases, has proven to cause instability problems. The model calculates pure advection by the explicit Holly-Preissmann method of characteristics, and diffusion plus source/sink terms by an extended implicit alternate-direction (ADI) method. By comparison with analytical results for fronts and discrete mass releases it is established that numerical separation of differential operators does not induce significant errors in the solution or the physical realism of the results. The numerical scheme is accurate, stable and efficient because it eliminates the need to solve a pentadiagonal algebraic systems, replacing it with two tridiagonal ones. The computational method is intended for further use in the, study of a two-dimensional lake hydrodynamic and transport field, driven either by forced (wind induced) or natural (buoyancy induced) convection.Office of Research and Development, US Environmental Protection Agency; Mid-Continent Ecology Division, US Environmental Protection Agenc

Stereospecific ligands and their complexes, Part VIII: Antimicrobial activity of palladium(II) complexes with 0,0'-dialkyl esters of (S,S)-ethylenediamine-N,N'-di-2-(4-methyl)-pentanoic acid

Palladium(II) complexes (1-4) of general formula [PdCl2(R2-S,S-eddp)] with bidentate N,N'- -ligands, O,O'-dialkyl esters (R = ethyl, n-propyl, n-butyl and n-pentyl), of (S,S)-ethylenediamine- N,N'-di-2-(4-methyl)pentanoic acid (S,S-eddp) were prepared and characterized by microanalysis, infrared and UV/Vis spectroscopy. The ligands and its complexes were tested for their in vitro antimicrobial activity against 15 species of bacteria and fungi. Testing is performed by the microdilution method, with the minimum inhibitory concentration (MIC) and the minimum microbicidal concentration (MMC) being determined. The MIC values were in range from 4.9 μg cm-3 to > 5000 μg cm-3 while MMC values ranged from 78 μg cm-3 to > 5000 μg cm-3. Palladium(II) complexes [PdCl2(Ln)] (n, 1-4) have statistically significant higher activity than the corresponding ligands. Complex 4 displayed the strongest activity among all tested compounds

Theories on the beginnings and structure of joint-families ("zadruga")

In this paper the author has a critical standpoint toward the most known theories on joint family communities. The works of the up-to-now called Yugoslav authors were put in the foreground. The works of foreign authors were placed after. They were classified by a general criterion, by how the authors saw the origins of this form of family. The comprehension of the basic characteristics depends, as a rule, on that, as well as the elements structure, changing processes, adjustment to new conditions and extinction of the joint family community. The first part of this article is devoted to theories about family communities as an institution of the Slavs. In this way its origin is connected with elements of a certain ethnic community. The range and consequences of such beliefs are suggested. The second part is reserved to explaining the family community as an institution which appeared in feudalism. It is a consequence of the tax system role. With its termination, the communities fell apart. This kind of social development determination and this type of family is proven to be ahistorical. It is predominantly stressed that the authors neglected that feudalism was a class society and overemphasized the force factor significance. The third part deals with theories which believe joint-family communities as an institution which arose in the transition from tribal to class society. These researchers stress that it is a general, historically determined conditioned form, which originated before class society and terminated with its development. Elements of its structure are especially important, as well as methods of its transformation in new conditions and termination processes. The essence of this belief is the following: a joint-family is a general historical form of family organization which arose in the transition from tribal to class society. The most important characteristics are: 1) blood relationship among men members; 2) common property; 3) undeveloped division of labor, and plain peoples work is the most important for its survival; 4) democratic control; and 5) it is not just mere gathering of simple families it is based on kinship, origin and precedes monogrammed families