Comparative analyses of the vascular flora of the Pčinja river gorges in Serbia and Macedonia

The study’s aim is the comparative chorologic and ecological analysis of the vascular flora of the two gorges of the Pčinja River in Serbia and Macedonia which are 27 km apart. In the two gorges 1564 taxa have been recorded, 1057 being in the upper gorge in Serbia and 1174 in the lower gorge in Macedonia. Common to both gorges are 666 taxa. Chorological spectra show that in both gorges the most abundant are Mediterranean-submediterranean plants, 32.85% being in the upper and 43.97% in the lower gorge. Differences in the studied vegetation result from a diverse participation of other floristic elements such as Central European ones that are more abundant in the upper gorge (17.05%) than in the lower gorge (10.86 %). The life-form spectrum reveals that the flora in both gorges is hemicryptophyte-therophyte in character. Both gorges belong to an enclave of a Mediterranean-submediterranean region, i.e. to its submediterranean Macedonian- Thracian province

Preparation of composite material BCP/DLPLG with a different content of ceramic and polymer component

Using a new approach of synthesis, homogenisation of DLPLG polymer powder and BCP gel, BCP/DLPLG composite material has been obtained with morphological and structural characteristics making it potentially very suitable for practical application in certain fields of the reconstructive medicine. The composite material has been synthesised with different ratios of ceramics and polymer BCP/DLPLG; 65/35w/w, 10/90 w/w, 5/95 w/w and 2/98w/w. The samples were characterized by Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM).Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Atomic swelling upon compression

The hydrogen atom under the pressure of a spherical penetrable confinement potential of a decreasing radius $r_{0}$ is explored, as a case study. A novel counter-intuitive effect of atomic swelling rather than shrinking with decreasing $r_{0}$ is unraveled, when $r_{0}$ reaches, and remains smaller than, a certain critical value. Upon swelling, the size of the atom is shown to increase by an order of magnitude, or more, compared to the size of the free atom. Examples of changes of photoabsorption properties of confined hydrogen atom upon its swelling are uncovered and demonstrated.Comment: 5 pages, 4 figure

Numerical Prediction of Nucleate Pool Boiling Heat Transfer Coefficient under High Heat Fluxes

This paper presents computational fluid dynamics approach to prediction of the heat transfer coefficient for nucleate pool boiling under high heat fluxes. The 3-D numerical simulations of the atmospheric saturated pool boiling are performed. Mathematical modelling of pool boiling requires a treatment of vapor-liquid two-phase mixture on the macro level, as well as on the micro level, such as bubble growth and departure from the heating surface. Two-phase flow is modelled by the two-fluid model, which consists of the mass, momentum, and energy conservation equations for each phase. Interface transfer processes are calculated by the closure laws. Micro level phenomena on the heating surface are modelled with the bubble nucleation site density, the bubble resistance time on the heating wall and with the certain level of randomness in the location of bubble nucleation sites. The developed model was used to determine the heat transfer coefficient and results of numerical simulations are compared with available experimental results and several empirical correlations. A considerable scattering of the predictions of the pool boiling heat transfer coefficient by experimental correlations is observed, while the numerically predicted values are within the range of results calculated by well-known Kutateladze, Mostinski, Kruzhilin, and Rohsenow correlations. The presented numerical modelling approach is original regarding both the application of the two-fluid two-phase model for the determination of heat transfer coefficient in pool boiling and the defined boundary conditions at the heated wall surface

The impact of high-end climate change on agricultural welfare

Climate change threatens agricultural productivity worldwide, resulting in higher food prices. Associated economic gains and losses differ not only by region but also between producers and consumers and are affected by market dynamics. On the basis of an impact modeling chain, starting with 19 different climate projections that drive plant biophysical process simulations and ending with agro-economic decisions, this analysis focuses on distributional effects of high-end climate change impacts across geographic regions and across economic agents. By estimating the changes in surpluses of consumers and producers, we find that climate change can have detrimental impacts on global agricultural welfare, especially after 2050, because losses in consumer surplus generally outweigh gains in producer surplus. Damage in agriculture may reach the annual loss of 0.3% of future total gross domestic product at the end of the century globally, assuming further opening of trade in agricultural products, which typically leads to interregional production shifts to higher latitudes. Those estimated global losses could increase substantially if international trade is more restricted. If beneficial effects of atmospheric carbon dioxide fertilization can be realized in agricultural production, much of the damage could be avoided. Although trade policy reforms toward further liberalization help alleviate climate change impacts, additional compensation mechanisms for associated environmental and development concerns have to be considered

Citogenetička analiza ćelija kostne srži pacova tretiranih toluenom

The paper presents the results of investigations of the effect of toluene on bone marrow cells of female Wistar rats treated intraperitoneally with toluene for 8 or 11 days, in doses of 0.602 μg/200 g body mass. Cytogenetic analyses were performed on the metaphase figure of chromosomes in order to determine the frequency of structural aberrations – breaks and gaps. The values of the mitotic index and number of poliploid cells were determined. No significant increase was determined in the frequency of breaks and gaps in chromosomes of treated animals in comparison with the controls, which means that, under the experimental conditions, toluene did not exhibit a definite genotoxic effect. However, it has been determined that there was a significant increase in the value of the mitotic index, as well as a significant increase in the number of poliploid cells in both groups of treated rats in comparison with controls.U ovom radu su navedeni rezultati ispitivanja efekata toluena na ćelije kostne srži ženki Wistar pacova, koji su intraperitonealno dobijali toluen tokom 8 i 11 dana, u dozi od 0.602 μg /200 g telesne mase. Citogenetički su analizirane metafazne figure hromozoma da bi se utvrdila učestalost pojavljivanja strukturnih aberacija – prekida i gapova. Utvrđene su vrednosti mitotskog indeksa i broja poliploidnih ćelija. Nije ustanovljeno značajno povećanje učestalosti pojavljivanja prekida i gapova na hromozomima tretiranih jedinki u odnosu na kontrole, što znači da u uslovima ovog eksperimenta toluen nije iskazao nesumnjiv genotoksični efekat. Međutim ustanovljeno je značajno povećanje vrednosti mitotskog indeksa, kao i značajno povećanje broja poliploidnih ćelija u obe grupe tretiranih pacova u odnosu na kontrole