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Vera Slaveykova-Startcheva

Cette personne a quitté l’EPFL

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Publications associées (34)

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Cu and Pb accumulation by the marine diatom Thalassiosira weissflogii in the presence of humic acids

Vera Slaveykova-Startcheva

Metal complexation by dissolved organic matter, as humic acids, is considered to decrease metal bioavailability by lowering the free metal ion concentration. However, dissolved organic matter adsorption on cell surfaces can modify cell membrane properties, ...

2010

Effect of humic acid on Cd(II), Cu(II) and Pb(II) uptake by freshwater algae: kinetic and cell wall speciation considerations

Vera Slaveykova-Startcheva, Cristina Lamelas

The present study examines the effect of humic acid on the uptake kinetics of Cd(II), Cu(II), and Pb(II) by the freshwater alga Chlorella kesslerii. The results demonstrated that the relative proportion of Pb in the cell wall layer is greater than that of ...

2009

Comparison of Cd(II), Cu(II) and Pb(II) Biouptake by Green Algae in the Presence of Humic Acid

Vera Slaveykova-Startcheva, Cristina Lamelas

The present study examines the role of humic acid, as a representative of dissolved organic matter, in Cd(II), Cu(II) and Pb(II) speciation and biouptake by green microalgae. Cellular and intracellular metal fractions were compared in the presence of citri ...

2007

Characterization of the colloidal organic matter from the Amazonian basin by asymmetrical flow field-flow fractionation and size exclusion chromatography

Vera Slaveykova-Startcheva

Colloidal organic matter (COM) collected in small and large watercourse tributaries of the Negro River (Brazil) were fractionated and characterized by an asymmetrical flow field-flow fractionation (AFIFFF) coupled to UV and seven angle laser light scatteri ...

Elsevier2010

Asymmetrical flow field-flow fractionation coupled to multi-angle light scattering detector: optimization of crossflow rate, carrier characteristics and injected mass in alginate separation

Vera Slaveykova-Startcheva

The coupling of the flow field flow fractionation to differential refractive index (DRI) and multi-angle laser light scattering detectors is a powerful tool for characterizing charged polysaccharides such as alginate. However, the correct interpretation of ...

2007

Effects of extraction methods on the composition and molar mass distributions of exopolymeric substances of the bacterium Sinorhizobium meliloti

Vera Slaveykova-Startcheva

The influence of the extraction methods on the composition, size diversity, molar mass and size distributions of exopolymeric substances (EPS) from the bacterium Sinorhizobium meliloti wild type (WT) and by the exoY strain deficient in exopolysaccharide pr ...

Elsevier2012

Effect of Humic Substance Photoalteration on Lead Bioavailability to Freshwater Microalgae

Pascal Miéville, Vera Slaveykova-Startcheva

The present study provides results on the influence of humic substance (HS) photoalteration on lead availability to the freshwater microalga Chlorella kesslerii. The evolution of the free lead-ion concentrations measured by the ion exchange technique [Pb]( ...

2011

Electrohydrodynamic Properties of Succinoglycan as Probed by Fluorescence Correlation Spectroscopy, Protolytic Titration and Capillary Electrophoresis

Vera Slaveykova-Startcheva

The electrostatic, hydrodynamic and conformational properties of aqueous solutions of succinoglycan have been analyzed by fluorescence correlation spectroscopy (FCS), proton titration, and capillary electrophoresis (CE) over a large range of pH values and ...

American Chemical Society2006

Predicting Pb Bioavailability to Freshwater Microalgae in the Presence of Fulvic Acid: Algal Cell Density as a Variable

Vera Slaveykova-Startcheva

In order to better understand the relationship between lead speciation and its bioavailability in natural waters, the interactions between Pb(II), fulvic acid and the freshwater alga, Chlorella kesslerii were studied at different algal cell densities. An i ...

Elsevier2007

Amine- and carboxyl-quantum dots affect membrane integrity of bacterium Cupriavidus metallidurans CH34

Vera Slaveykova-Startcheva

The present study examines the interaction of amine- and carboxyl- PEG core/shell quantum dots (QDs) with metal resistant bacterium Cupriavidus metallidurans CH34. The evolution of the number of QDs, their hydrodynamic radius, diffusion coefficients and si ...

2009

Determination of trace metals accumulated and internalized by marine phytoplankton; interferences with colloidal organic matter

Vera Slaveykova-Startcheva

In the present work, we study the effects that aggregation of humic acids in seawater, and its adsorption to surfaces, can have on the determination of Cu and Pb accumulation by phytoplankton within the context of metal bioavailability studies, using the d ...

Taylor & Francis Ltd2012

Exopolysaccharides produced by bacteria isolated from the pelagic Southern Ocean - Role in Fe binding, chemical reactivity, and bioavailability

Vera Slaveykova-Startcheva

As a result of ubiquitous excretion by micro-organisms, extracellular polymeric substances are reported in high concentrations in marine systems. The majority of this material is exopolysaccharide (EPS). Despite previous studies showing that EPS can affect ...

Elsevier2011

Species-species interactions modulate copper toxicity under different visible light conditions

Vera Slaveykova-Startcheva, Valérie Gagnaux

Combination of biotic and abiotic factors influences the effects of naturally occurring or anthropogenic chemicals on photosynthetic microorganisms in the aquatic environment. Nonetheless, the combined effects of physical stressors and species-species inte ...

ACADEMIC PRESS INC ELSEVIER SCIENCE2019

Characterization of H+ and Cd2+ Binding Properties of Bacterial Exopolymers

Vera Slaveykova-Startcheva, Cristina Lamelas

The proton and Cd binding capacities of microbially produced exopolysaccharides, EPS, were quantified by the determination of complex stability constants and the concentration of complexing sites using H+ or Cd2+ selective electrodes in dynamic titrations. ...

Elsevier2006

Terrestrial ecotoxicity and effect factors of metals in life cycle assessment (LCA)

Vera Slaveykova-Startcheva

Life cycle impact assessment aims to translate the amounts of substance emitted during the life cycle of a product into a potential impact on the environment, which includes terrestrial ecosystems. This work suggests some possible improvements in assessing ...

Elsevier2007

Modeling of Cd Uptake and Efflux Kinetics in Metal-Resistant Bacterium Cupriavidus metallidurans

Vera Slaveykova-Startcheva

The Model of Uptake with Instantaneous Adsorption and Efflux, MUIAE, describing and predicting the overall Cd uptake by the metal-resistant bacterium Cupriavidus metallidurans CH34, is presented. MUIAE takes into account different processes at the bacteria ...

2010

Sensing the dynamics of oxidative stress using enhanced absorption in protein-loaded random media

Olivier Martin, Christian Santschi, Vera Slaveykova-Startcheva, Guillaume Suarez

Reactive oxygen species play a key role in cell signalling and oxidative stress mechanisms, therefore, sensing their production by living organisms is of fundamental interest. Here we describe a novel biosensing method for extracellular detection of endoge ...

Nature Publishing Group2013

Uptake of Cd(II) and Pb(II) by microalgae in presence of colloidal organic matter from wastewater treatment plant effluents

Vera Slaveykova-Startcheva

The present study addresses the key issue of linking the chemical speciation to the uptake of priority pollutants Cd(II) and Pb(II) in the wastewater treatment plant effluents, with emphasis on the role of the colloidal organic matter (EfOM). Binding of Cd ...

2010

Do Exudates Mitigate Cd Biouptake by Rhizobacterium Sinorhizobium melilotii?

Vera Slaveykova-Startcheva

To better understand the role of exudates in Cd speciation and biouptake by bacterium Sinorhizobium meliloti, the content of different exudate components including siderophores, proteins and polysaccharides were quantified in absence and presence of 10M C ...

2006

Assessment of metal-extracellular polymeric substances interactions by asymmetrical flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry

Vera Slaveykova-Startcheva

Extracellular polymeric substances (EPSs) excreted by the bacterium Sinorhizobium meliloti and associated Ca, Cd and Pb were characterised by asymmetrical flow field-flow fractionation coupled with UV spectrophotometry and inductively coupled plasma mass s ...

2010