57 research outputs found
Reversible binding of metal ions onto bacterial layers revealed by protonation-induced ATR-FTIR difference spectroscopy
No full textThe ability of microorganisms to adhere to abiotic surfaces and the potentialities of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy have been exploited in order to study protonation and heavy metal binding events onto bacterial surfaces. This work represents the first attempt to apply on bacteria the recently developed method known as perfusion-induced ATR-FTIR difference spectroscopy. Such technique allows measurement of even slight changes in the infrared spectrum of the sample, deposited as a thin layer on an ATR crystal, while an aqueous solution is perfused over its surface. Solutions at different pH have been used for inducing protonation/deprotonation of functional groups lying on the surface of Rhodobacter sphaeroides cells, chosen as a model system. The interaction of Ni2+ with surface protonable groups of this microorganism has been investigated with a double-difference approach exploiting competition between nickel cations and protons. Protonation-induced difference spectra of simple model compounds have been acquired in order to guide band assignment in bacterial spectra, thus allowing identification of major components involved in proton uptake and metal binding. The data collected reveal that carboxylate moieties on the bacterial surface of R. sphaeroides play a role in extracellular biosorption of Ni2+, establishing with this ion relatively weak coordinative bonds
Reversible Binding of Metal Ions onto Bacterial Layers Revealed by Protonation-Induced ATR-FTIR Difference Spectroscopy
No full textThe ability of microorganisms to adhere to abiotic surfaces and the potentialities of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy have been exploited to study protonation and heavy metal binding events onto bacterial surfaces. This work represents the first attempt to apply on bacteria the recently developed method known as perfusion-induced ATR-FTIR difference spectroscopy.(1,2) Such a technique allows measurement of even slight changes in the infrared spectrum of the sample, deposited as a thin layer on an ATR crystal, while an aqueous solution is perfused over its surface. Solutions at different pH have been used for inducing protonation/deprotonation of functional groups lying on the surface of Rhodobacter sphaeroides cells, chosen as a model system. The interaction of Ni2+ with surface protonable groups of this microorganism has been investigated with a double-difference approach exploiting competition between nickel cations and protons. Protonation-induced difference spectra of simple model compounds have been acquired to guide band assignment in bacterial spectra, thus allowing identification of major components involved in proton uptake and metal binding. The data collected reveal that carboxylate moieties on the bacterial surface of R. sphaeroides play a role in extracellular biosorption of Ni2+, establishing with this ion relatively weak coordinative bonds
X-ray photoelectron spectroscopy as a non-conventional analytical technique for bio-organic materials characterization: the example of Arbacia lixula.
No full textPurple photosynthetic bacteria and sea urchin coelomocytes examination by X‐ray photoelectron spectroscopy as a non‐conventional analytical technique for bio‐organic materials
No full textPhenol chemisorption onto phthalocyanine thin layers probed by ATR-FTIR difference spectroscopy
No full textAttenuated total reflection Fourier transform infrared
(ATR-FTIR) difference spectroscopy has been employed as a
powerful method for the comprehension of active layer–
analyte interactions, revealing interesting mechanistic aspects
concerning the binding of halogen-substituted phenols onto
phthalocyanine Langmuir–Schaefer films
The phototrophic bacterium Rhodobacter sphaeroides as a bio-catalyst for the reduction of Chromate to Chromium(III)
No full text
Home and Mortgage Ownership of the Dutch Elderly: Explaining Cohort, Time and Age Effects
Get PDFThe relationship between home ownership of Dutch elderly households and age is strongly negative. Other studies suggest that this age gradient should be attributed to a cohort effect. In this paper we investigate where those cohort effects come from. We also observe that mortgage ownership among elderly home-owners increased considerably during the nineties. Using panel data we estimate models explaining home and mortgage ownership by age, cohort, and time effects, as well as other factors. Cohort and time effects are modelled explicitly using macro economic and housing market related variables. We find that the level of GDP per capita when the household head was young is the main factor explaining generation effects in home ownership among the elderly. After accounting for cohort effects it also appears that home ownership decreases slightly with age. Mortgage ownership among elderly home owners rose considerably during the nineties due to house price increases and due to financial innovation in the mortgage market. Cohort effects are also important. A supplementary analysis suggests that those cohort effects are due to the fact that the accidental bequest motive is becoming less important.home ownership, mortgages, cohort effects
Bacterial phototrophic biomass as biosorbent for the removal of Nickel(II) from waste-waters
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