Global NEST Journal

The present study is performed with the aim to reduce the levels of polluting emissions from fuel combustion that produce acid rains and the greenhouse effect (NOx, CO2). The electric field effects on the processes of heat/mass transfer and propane combustion are studied in order to perform electric control of the levels of polluting emissions from the flame. The results of experimental studies show the direct influence of the electric field's enhanced mass transfer on local variations of the flame composition and fuel combustion. The related variations of the flame temperature, processes of soot formation, carbon capture and deposition along the flame channel flow are studied by varying the field strength and the equivalence ratio of the propane-air mixture. The results show that the electric field effect on soot for- mation, carbon capture and sequestration, for fuel-rich flame flow, can be used to reduce the levels of CO2 emissions from the flame. In addition, the field-enhanced heat/ mass transfer to the channel walls, for fuel-lean conditions, can be used to control the fuel combustion, flame temperature and temperature- sensitive levels of NOx emissions. The most pronounced electric field effects on fuel combustion and composition of the products are observed in the limit of the weak fields (U<1,2 kV, E<105 V m-1).

The malaria situation in Bulgaria during the past decade of the century was analysed and the evaluation
of the risk of re-emerging of the diseases and factors determining it in the phase of maintanence
of malaria eradication was carried out. The epidemiological analysis of malaria cases notified during
the period 1991-2000 in Bulgaria is presented. Of a total of 382 malaria episodes registered, 363
(95.03%), were imported into Bulgaria from endemic countries, 1 (0.26%) occurred after haemotransfusion
and 18 (4.71%) were indigenous introduced ones. Plasmodium falciparum accounted for 68.59%
of all imported cases, P.vivax, for 23.82%, P.ovale, for 2.36%, P.malariae, for 1.85%. In 1.83% more
than one species was detected, and in 6 cases, the species was not identified. The import of malaria
came mainly from Africa-299 (82.37%) cases, followed by Asia-63 (17.36%) and Oceania-1 (0.27%).
Four cases with falciparum malaria resulted in death. A great number of imported cases-231 (63.81%)
was diagnosed during the potential malaria season in Bulgaria (April-October). The analysis of present
entomological situation showed a high density of Anopheles population. As an indication for existence
of potential risk of spread of indigenous malaria, especially in cases of delayed diagnosis and treatment,
18 indigenous cases of vivax malaria were recorded in 1995-1996 in the region of the town of Sandanski,
for the first time after malaria eradication in 1965. The cases were classified as introduced ones. The
analysis of the essential malaria import in Bulgaria, climatic conditions and presence of Anopheline
species revealed a fairly high level of malariogenic potential. The stratification of the country was carried
out in accordance with the degree of hazard of malaria spreading, and the territory was divided
into three categories of regions: with high-, medium- and low-risk. The present situation, that probably
will be valid for the future, too, requires a scientific based prognosis and improvement of a system of
surveillance activities aiming at prevention of indigenous endemic and epidemic spreading of malaria
in the country, as well as elaboration of adequate activities of the health network in case of reappearance
of autochthonous cases.

The paper presents some interesting results of metal speciation studies employing Anodic Stripping
Voltammetry (ASV) applied in a dynamic natural system such as the brakish – marine interface formed
between the polluted waters discharged by the Koumoundouros lake and the marine ones of the Gulf
of Elefsis.
The distributions and behaviour of various forms of Pb, Cd and Zn have been followed seasonally. Four
categories of dissolved species were identified (very labile, moderately labile, slowly labile and inert),
as well as particulate species. It was found that their relative contribution and patterns are determined
by three main factors: salinity, pH, and the presence of dissolved organic carbon. Increasing salinity
stimulates formation of very labile chloro-complexes, while increasing pH stimulates the formation of
inert species and particulates. A considerable part of slowly labile species seems to be metal complexes
with organic ligands.

This work illustrates the use and some related results of Artificial Neural Networks (ANNs) for data
quality control of environmental time series and for reconstruction of missing data. ANNs are applied
to the following problems: i) short and medium-term predicting of air pollutant concentrations in urban
areas, ii) interpolating and extrapolating daily maximum temperature, iii) replacing time distribution
with spatial distributed information (pollutant concentrations at different measuring sites). Observed
versus predicted data are compared to test the efficacy of ANNs in simulating environmental processes.
Results confirm ANNs as an improvement of classical models and show the utility of ANNs for
restoration of time series..