Nutrient Balance from Agricultural Pollution Sources on Selected Tributaries to the Švihov Reservoir

Agriculture is the leading source of non-point sources of water pollution, especially in terms of the runoff process. Agricultural management promotes extensive water contamination, soil erosion and sedimentation in streams and reservoirs. The water reservoir Švihov on the Želivka river supplies drinking water to more than 1.5 million people. The catchment area of the water supply reservoir is intensively used for agriculture, more than 55% of the catchment area is arable land. Nutrients such as phosphorus and nitrates in the upper water-ways of tributaries are a huge problem. The aim of the research is to evaluate concentration trends and losses of nutrients (nitrates and phosphorus) at the chosen tributaries to the Švihov reservoir during 2018-2021. From the data on monthly concentrations and monthly discharges the monthly and annual losses of nitrates and phosphorus on each profile were calculated. The effect of discharges and concentrations on the magnitude of losses was investigated by correlation analysis. The influence of the forebay Trnávka dam on the magnitude of nutrient losses was also evaluated. The results show the importance of discharge magnitude on nutrient losses. The Trnávka forebay dam significantly reduces the transport of phosphorus from the Trnava catchment to the Švihov reservoir. In the catchment area of the reservoir it is recommended to implement nature-friendly and technical measures for water retention and accumulation in the landscape in order to reduce nutrient transport.O

Studium fázového přechodu ferroelektirického-ferroelastického KD2PO4 tvaru fázového rozhranní v závislosti na gradientu teploty

Etude de la transition ferroelectrique-ferroelastique du KD2PO4 forme du front de phase en fonction du gradient thermique The thesis explores complex process of first order transition of KD2PO4 crystal from tetragonal phase to ferroelectric - ferroelastic orthorhombic phase and back at temperature 209 K. The experimental set up of nitrogeneous cryostat allowes temperature and temperature gradient variations during simultaneous three axes optical sample observations, dielectric measurements. The discontinous change of order parameters especially strain uzz along tetragonal-feroelectric axis is important for form of phase front, which tents to be perpendicular to tetragonal axis z. To the contrary, if external electric field along tetragonal ferrolectric axis is applied, phase front tents to be parallel to applied electric field. Coupled strain shear and electric polarisition of orthorhombic low symetry phase are compensated by domain structure. The observed flat and zigzag shapes of phase front under different experimental conditions are explained. It is shown that the resulting shape which is often of a zigzag form for temperature gradient perpendicular to ferroelectric axis follows from the competition between the free energy induced by the gradient, the elastic-strain energy caused by lattice misfits...Studium fázového přechodu ferroelektirického-ferroelastického KD2PO4 tvaru fázového rozhranní v závislosti na gradientu teploty Doktorská práce se zaměřuje na kompexní proces fázového přechodu 1. druhu v krystalu KD2PO4 z tetragonální fáze do ferroelektrické-ferroelastické ortorombické a zpět při teplotě 209 K. Experimentální uspořádání dusíkového kryostatu umožňovalo měnit teplotu a teplotní gradient během současného optického pozorování vzorku, dielektrického měření. Skoková změna parametru uspořádání, zvláště deformace uzz podél tetragonální-ferroelektrické osy je důležitá pro tvar fázového rozhraní, které se snaží být kolmé k tetragonální ose z. Naopak, pokud je aplikováno vnější elektrické pole podél tetragonální feroelektrické osy , fázové rozhraní se snaží být paralelení s aplikovaným elektrickým polem. Vázaný střih a elektrická polarizace v ortorombické fázi s nižší symetrií jsou kompenzovány doménovou strukturou. Jsou vysvětleny pozorované rovinné či zalomené tvary fázového rozhranní v rozdílných expetrimentálních situacích. Je ukázáno, že výsledný tvar rozhraní, který je často zalomený pro teplotní gradient kolmý k ferroleketrické ose minimalizuje volnou energii vyvolanou teplotním gradientem, elastickou energii vyvolanou rozdílnou velikostí mřížek v obou fázích a plošnou energii rozhranní....Department of Condensed Matter PhysicsKatedra fyziky kondenzovaných látekFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Water Quality of Agricultural Drainage Systems in the Czech Republic — Options for Its Improvement

Hydrology & the hydrospher

Creation of Methodology of Planning of Process Control of Production

Plánování, optimalizace, řízení výroby, procesní řízení, výroba, ERPPlanning, optimalization, production management, process management, production, ERP

Quantification of purine basis in their mixtures at femto-molar concentration levels using FT-SERS

Surface-enhanced Raman scattering spectroscopy represents one of the unique techniques for studying nanoscale objects, and its distinctive properties can be used in the process of further analysis. The careful evaluation of the particular influence of selected key-role experimental parameters (e.g. pH value of measured sample mixture, size and distribution of used nanoparticles) and the influence of reduction agent used in the process of formation of desired nanoparticle objects presents an important task in the further study of surface-enhanced Raman scattering effect. A broad study of these experimental parameters was performed in this paper. The main aim of the presented work was to a demonstrate an application potential of selected experimental conditions in the determination of three purine bases: adenine, xanthine, and hypoxanthine. The resulting limits of detection are at femtomolar concentration levels for all three studied compounds

Silver nanoparticles : influence of stabilizing agent and diameter on antifungal activity against Candida albicans and Candida glabrata biofilms

Aim : The purpose of this work was to evaluate the size-dependent antifungal activity of different silver nanoparticles (SN) colloidal suspensions against Candida albicans and Candida glabrata mature biofilms. Methods and Results:  The research presented herein used SN of three different average sizes (5, 10 and 60 nm), which were synthesized by the reduction of silver nitrate through sodium citrate and which were stabilized with ammonia or polyvinylpyrrolidone. Minimal inhibitory concentration (MIC) assays were performed using the microdilution methodology. The antibiofilm activity of SN was determined by total biomass quantification (by crystal violet staining) and colony forming units enumeration. MIC results showed that all SN colloidal suspensions were fungicidal against the tested strains at very low concentrations (0·4–3·3 μg ml−1). With regard to biomass quantification, SN colloidal suspensions were very effective only against C. glabrata biofilms, achieving biomass reductions around 90% at a silver concentration of 108 μg ml−1. In general, all SN suspensions promoted significant log10 reduction of the mean number of cultivable biofilm cells after exposure to silver concentrations at or higher than 108 μg ml−1. Moreover, the results showed that the particle size and the type of stabilizing agent used did not interfere in the antifungal activity of SN against Candida biofilms. Conclusions:  This study suggests that SN have antifungal therapeutic potential, but further studies are still required namely regarding formulation and delivery means. Significance and Impact of the Study:  SN may contribute to the development of new strategies for the improvement of oral health and quality of life particularly of the complete denture wearers.This study was supported by the Coordenacao de Aperfeicoamento de Pessoal de Nivel superior (CAPES), Brazil, grant BEX 1221/10-8. The authors are indebted to LIEC-CMDMC and INCTMN/FAPESP-CNPq for preparing and characterizing the colloidal suspensions of SN. The authors also thank George Duchow for the English review

Noble Metal Nanostructures Influence of Structure and Environment on Their Optical Properties

Optical properties of nanostructured materials, isolated nanoparticles, and structures composed of both metals and semiconductors are broadly discussed. Fundamentals of the origin of surface plasmons as well as the surface plasmon resonance sensing are described and documented on a number of examples. Localized plasmon sensing and surface-enhanced Raman spectroscopy are subjected to special interest since those techniques are inherently associated with the direct application of plasmonic structures. The possibility of tailoring the optical properties of ultra-thin metal layers via controlling their shape and morphology by postdeposition annealing is documented. Special attention is paid to the contribution of bimetallic particles and layers as well as metal structures encapsulated in semiconductors and dielectrics to the optical response. The opportunity to tune the properties of materials over a large scale of values opens up entirely new application possibilities of optical active structures. The nature of surface plasmons predetermines noble metal nanostructures to be promising great materials for development of modern label-free sensing methods based on plasmon resonance—SPR and LSPR sensing

Application of elastostatic Green function tensor technique to electrostriction in cubic, hexagonal and orthorhombic crystals

The elastostatic Green function tensor approach, which was recently used to treat electrostriction in numerical simulation of domain structure formation in cubic ferroelectrics, is reviewed and extended to the crystals of hexagonal and orthorhombic symmetry. The tensorial kernels appearing in the expressions for effective nonlocal interaction of electrostrictive origin are derived explicitly and their physical meaning is illustrated on simple examples. It is argued that the bilinear coupling between the polarization gradients and elastic strain should be systematically included in the Ginzburg-Landau free energy expansion of electrostrictive materials.Comment: 4 page

"Soft and rigid" dithiols and Au nanoparticles grafting on plasma-treated polyethyleneterephthalate

Surface of polyethyleneterephthalate (PET) was modified by plasma discharge and subsequently grafted with dithiols (1, 2-ethanedithiol (ED) or 4, 4'-biphenyldithiol) to create the thiol (-SH) groups on polymer surface. This "short" dithiols are expected to be fixed via one of -SH groups to radicals created by the plasma treatment on the PET surface. "Free" -SH groups are allowed to interact with Au nanoparticles. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and electrokinetic analysis (EA, zeta potential) were used for the characterization of surface chemistry of the modified PET. Surface morphology and roughness of the modified PET were studied by atomic force microscopy (AFM). The results from XPS, FTIR, EA and AFM show that the Au nanoparticles are grafted on the modified surface only in the case of biphenyldithiol pretreatment. The possible explanation is that the "flexible" molecule of ethanedithiol is bounded to the activated PET surface with both -SH groups. On the contrary, the "rigid" molecule of biphenyldithiol is bounded via only one -SH group to the modified PET surface and the second one remains "free" for the consecutive chemical reaction with Au nanoparticle. The gold nanoparticles are distributed relatively homogenously over the polymer surface