Cathodoluminescence is a phenomenon of some materials which is generated by electron beam interaction with a luminescence matter. The result of this interaction is production of the photons of infrared, visible and ultraviolet parts of electromagnetic spectrum. The technique to release the photons from luminescence materials can be applied to semiconductors, grains of minerals, chemical substances providing fluorescence; or specific labels bound to biological samples. The method serves for their deeper ultrastructural analysis. This presented study is focused on cryo-system which is a part of scanning electron microscope and its utilization in measurement of cathodoluminescence, especially the dependence of its spectrum on temperature of samples. and Katodoluminiscence je jev, který vzniká interakcí elektronového svazku s materiálem generujícím luminiscenci. Jeho výsledkem je produkce fotonů v infračervené, viditelné a ultrafialové oblasti elektromagnetického spektra. Metodika emise fotonů z luminiscenčních materiálů může být aplikována na polovodiče, zrna minerálů v horninách, chemické látky poskytující fluorescenci nebo specifické značky vázané na biologické vzorky a slouží k jejich hlubším analýzám. Předkládaná práce je zaměřena na využití systému chlazení vzorků v rastrovacím elektronovém mikroskopu a určení závislosti katodoluminiscenčního spektra na teplotě vzorku.
Arsenic release and its kinetic in severely contaminated stream sediments of the Kyjov brook and impoundment material (eastern Slovakia) using column and batch experiments was studied. The results of the column experiments showed that As release from the solid samples by water was likely controlled by Fe and Mn oxyhydroxides and pH of the sediments and leachates. It was also observed that extraction time was an important factor influencing the As release. The empirical correlations between the rate constants of As release and oxalate-extractable Fe content or total Mn content imply that diffusion in hydrated micropores of amorphous Fe and Mn oxides might be the rate-limiting mechanism of the As release. Although the fractions of As released in column experiments were generally less than 10 % of its total contents, these low fractions represented high absolute amounts of readily available and water-soluble As with a mean value of 83 mg kg-1. This amount of readily available As is approximately 4-times higher than the guideline value for As according to DEFRA UK, based upon ''bioavailable'' concentration, indicating high As availability for plants and living organisms in the studied region. and V štúdii bolo sledované uvoľňovanie arzénu a jeho rýchlosť vo výrazne kontaminovaných riečnych sedimentoch toku Kyjov na východnom Slovensku a materiáli odkaliska použitím kolónových a nádobkových experimentov. Výsledky kolónových experimentov naznačujú, že pravdepodobne najväčší vplyv na uvoľňovanie As vodou majú oxyhydroxidy Fe a Mn a pH výluhov a použitých sedimetov. Ukázalo sa, že aj čas trvania kontaktu kontaminovaných vzoriek s roztokom je dôležitý faktor uvoľňovania As. Nájdené korelácie medzi rýchlostnými konštantami uvoľňovania As a extrahovateľnými obsahmi Fe šťavelanom amónnym ako aj celkovými obsahmi Mn by mohli poukazovať na fakt, že difúzia v hydratovaných mikropóroch amorfných oxyhydroxidov Fe a Mn je hlavný mechanizmus limitujúci rýchlosť uvoľňovania As. Hoci frakcie uvoľneného As v kolónových experimentoch boli celkovo nižšie ako 10 % z jeho totálnych obsahov v skúmaných vzorkách, tieto nízke frakcie predstavujú vysoké obsahy ľahko dostupného a vo vode rozpustného As s priemernou hodnotou 83 mg kg-1. Uvedený obsah ľahko dostupného As je približne 4-krát vyšší ako smernicová hodnota podľa DEFRA UK založená na ''biodostupnej'' koncentrácii As. Toto porovnanie poukazuje na potenciálne vysokú dostupnosť As pre rastliny a živé organizmy v študovanej oblasti
A landscape genetics approach was applied to common goby (Pomatoschistus microps) sampled from three estuaries (six sites) of the Portuguese coast. Individuals of each site were genotyped for eight microsatellite loci and levels of genetic diversity and differentiation were correlated to present-day estuarine characteristics and historical events. A general ecological state for each sampling site was obtained from a principal component analysis (PCA) applied to estuarine geomorphologic characteristics and levels of heavy metals and total polycyclic aromatic hydrocarbons contamination. Genetic diversity was higher than that previously reported for common goby in the Atlantic and Mediterranean. FST were generally very low (0.000-0.049), as well as Nei’s genetic distances (0.000-0.167), although the later were statistically significant. Estuarine geomorphology and heavy metal contamination contributed the most to estuarine ecological differentiation but no trend was detected in the relationship between these characteristics and samples’ genetic diversity. Mantel tests also revealed no significant relationships between geographic, genetic and ecological distances. Null alleles only contributed to explain significant Hardy-Weinberg departures in two of the eight loci scored, although disequilibria were detected in at least two loci per sample. Notwithstanding its exploratory character, results suggest an important role for historical factors in the timing and direction of P. microps colonization of the Portuguese estuaries. Environmental variation and P. microps ability to cope with it are also structuring factors in establishing and maintaining the patchy genetic diversity detected in the studied estuaries.
In applications of stochastic programming, optimization of the expected outcome need not be an acceptable goal. This has been the reason for recent proposals aiming at construction and optimization of more complicated nonlinear risk objectives. We will survey various approaches to risk quantification and optimization mainly in the framework of static and two-stage stochastic programs and comment on their properties. It turns out that polyhedral risk functionals introduced in Eichorn and Römisch \cite{Eich-Ro} have many convenient features. We shall complement the existing results by an application of contamination technique to stress testing or robustness analysis of stochastic programs with polyhedral risk objectives with respect to the underlying probability distribution. The ideas will be illuminated by numerical results for a bond portfolio management problem.
Sorption of herbicides (acetochlor, atrazine, 2,4-D-DMA, chlorotoluron, MCPA and trifluralin) in six soils was evaluated. Among herbicides studied, dissociable herbicides (MCPA and 2,4-D-DMA) were the least sorbed, whereas nonionic herbicides were the most sorbed (acetochlor < chlorotoluron < trifluralin). The distribution coefficient values KD and equilibrium sorbed amounts positively correlated with soil organic carbon content for all herbicides except MCPA. Moreover, all herbicides except MCPA were the most sorbed in the Vertisoil (SA) with relatively high content of expanding clay minerals in proportion to organic carbon content. Organic carbon - water distribution coefficient values KOC for each herbicide showed a smaller variation among soils used except the SA soil than distribution coefficients KD. To estimate potential risk of groundwater contamination by herbicides investigated, measured KOC and treshold GUS values (Groundwater Ubiquity Score) were used to calculate half-lives t1/2 that would rank herbicides as potentially hazardous and non-hazardous. Comparison of calculated t1/2 values to published was found that atrazine and MCPA could be considered hazardous herbicides, trifluralin non-hazardous herbicide and acetochlor, 2,4-D and chlorotoluron could be hazardous or non-hazardous, depending on soil type. Presented analysis was also in line with risk assessment of groundwater contamination according to EPA (Environmental Protection Agency) criterion. and Referát prináša výsledky výskumu sorpcie herbicídov (acetochlór, atrazín, 2,4-D-DMA, chlórtoluron, MCPA a trifluralín) v šiestich poľnohospodárskych pôdach. V rámci sledovaných herbicídov najnižšie rovnovážne sorbované množstvá v pôdach boli zistené pre disociovateľné herbicídy (MCPA a 2,4-D-DMA) a najvyššie pre nepolárne herbicídy (acetochlór < chlórtoluron < trifluralín). Ukázalo sa, že s rastúcim podielom organického uhlíka v použitých pôdach sa priamo úmerne zvyšuje rovnovážne sorbované množstvo sledovaných herbicídov s výnimkou MCPA. Navyše, všetky herbicídy okrem MCPA sa najlepšie sorbovali v pôde smonica (SA) s relatívne vysokým podielom expandujúcich ílových minerálov v pomere k obsahu organického uhlíka. V rámci použitých pôd s výnimkou pôdy smonica (SA) boli rozdiely medzi zistenými hodnotami rozdeľovacích koeficientov normalizovaných na podiel organického uhlíka KOC pre daný herbicíd výrazne nižšie ako rozdiely medzi rozdeľovacími koeficientami KD. Na posúdenie potenciálneho rizika kontaminácie podzemných vôd skúmanými herbicídmi boli využité stanovené KOC a hraničné hodnoty ukazovateľa GUS (riziko výskytu organickej látky v podzemných vodách), z ktorých sa vypočítali žiadané polčasy rozkladu t1/2. Porovnaním vypočítaných t1/2 s publikovanými v literatúre sa dospelo k záveru, že atrazín a MCPA možno považovať za rizikové herbicídy vo všetkých pôdach, trifluralín za herbicíd bez rizika a acetochlór, 2,4-D a chlórtoluron za rizikové alebo bez rizika v závislosti od pôdneho typu. Uvedená analýza sa zhodovala aj s analýzou možného rizika kontaminácie podľa kritérií EPA.
Following the Article 16 (7) of the Directive 2000/60/EC of the European Parliament and of the Council establishing a framework for Community action in the field of water policy Commission shall submit proposals for environmental objectives applicable to the concentrations of the priority substances in surface water, sediments or biota. In the absence of agreement at Community level up to the deadline given by the directive Member States shall establish environmental objectives themselves. Within the framework of legislative preparation to this situation we have evaluated the relationships between particular parameters of surface water and total suspended solids contamination with heavy metals and with arsenic as one group of priority substances. Neither valid Decree No 82/1999 Coll. nor the amendment include such environmental objectives at present. and Podle čl. 16 (7) Směrnice 2000/60/ES Evropského parlamentu a Rady ustavující rámec pro činnost Společenství v oblasti vodní politiky má Komise předložit Evropskému parlamentu a Radě návrhy environmentálních standardů pro koncentrace prioritních látek v povrchových vodách, sedimentech a v biotě. V případě absence úmluvy na úrovni Společenství do termínu daného směrnicí musejí členské státy stanovit tyto environmentální standardy samy. V rámci legislativní přípravy na takovou eventualitu jsme proto hodnotili vztahy mezi jednotlivými parametry kontaminace vody a plavenin těžkými kovy a arsenem jako jednou skupinou prioritních látek. Platné Nař. vl. ČR č. 82/1999 Sb. ani připravovaná novela zatím environmentální standardy pro sedimenty (a tedy ani plaveniny) a biotu nezahrnují.