Ghent University

About: Ghent University is a education organization based out in Ghent, Belgium. It is known for research contribution in the topics: Population & Context (language use). The organization has 36170 authors who have published 111042 publications receiving 3774501 citations. The organization is also known as: UGent & University of Ghent.

Guidelines for terms related to chemical speciation and fractionation of elements. Definitions, structural aspects, and methodological approaches (IUPAC Recommendations 2000)

Abstract: This paper presents definitions of concepts related to speciation of elements, more particularly speciation analysis and chemical species Fractionation is distinguished from speciation analysis, and a general outline of fractionation procedures is given We propose a categorization of species according to isotopic composition of the element, its oxidation and electronic states, and its complex and molecular structure Examples are given of methodological approaches used for speciation analysis A synopsis of the methodology of dynamic speciation analysis is also presented

Endogenous DNA damage in humans: a review of quantitative data

Abstract: DNA damage plays a major role in mutagenesis, carcinogenesis and ageing. The vast majority of mutations in human tissues are certainly of endogenous origin. A thorough knowledge of the types and prevalence of endogenous DNA damage is thus essential for an understanding of the interactions of endogenous processes with exogenous agents and the influence of damage of endogenous origin on the induction of cancer and other diseases. In particular, this seems important in risk evaluation concerning exogenous agents that also occur endogenously or that, although chemically different from endogenous ones, generate the same DNA adducts. This knowledge may also be crucial to the development of rational chemopreventive strategies. A list of endogenous DNA-damaging agents, processes and DNA adduct levels is presented. For the sake of comparison, DNA adduct levels are expressed in a standardized way, including the number of adducts per 10(6) nt. This list comprises numerous reactive oxygen species and products generated as a consequence (e.g. lipid peroxides), endogenous reactive chemicals (e.g. aldehydes and S-adenosylmethionine), and chemical DNA instability (e.g. depurination). The respective roles of endogenous versus exogenous DNA damage in carcinogenesis are discussed.

Neonicotinoids in bees: a review on concentrations, side-effects and risk assessment

Abstract: Neonicotinoid insecticides are successfully applied to control pests in a variety of agricultural crops; however, they may not only affect pest insects but also non-target organisms such as pollinators. This review summarizes, for the first time, 15 years of research on the hazards of neonicotinoids to bees including honey bees, bumble bees and solitary bees. The focus of the paper is on three different key aspects determining the risks of neonicotinoid field concentrations for bee populations: (1) the environmental neonicotinoid residue levels in plants, bees and bee products in relation to pesticide application, (2) the reported side-effects with special attention for sublethal effects, and (3) the usefulness for the evaluation of neonicotinoids of an already existing risk assessment scheme for systemic compounds. Although environmental residue levels of neonicotinoids were found to be lower than acute/chronic toxicity levels, there is still a lack of reliable data as most analyses were conducted near the detection limit and for only few crops. Many laboratory studies described lethal and sublethal effects of neonicotinoids on the foraging behavior, and learning and memory abilities of bees, while no effects were observed in field studies at field-realistic dosages. The proposed risk assessment scheme for systemic compounds was shown to be applicable to assess the risk for side-effects of neonicotinoids as it considers the effect on different life stages and different levels of biological organization (organism versus colony). Future research studies should be conducted with field-realistic concentrations, relevant exposure and evaluation durations. Molecular markers may be used to improve risk assessment by a better understanding of the mode of action (interaction with receptors) of neonicotinoids in bees leading to the identification of environmentally safer compounds.

Continuous Electricity Generation at High Voltages and Currents Using Stacked Microbial Fuel Cells

Abstract: Connecting several microbial fuel cell (MFC) units in series or parallel can increase voltage and current; the effect on the microbial electricity generation was as yet unknown Six individual continuous MFC units in a stacked configuration produced a maximum hourly averaged power output of 258 W m(-3) using a hexacyanoferrate cathode The connection of the 6 MFC units in series and parallel enabled an increase of the voltages (202 V at 228 W m(-3)) and the currents (255 mA at 248 W m(-3)), while retaining high power outputs During the connection in series, the individual MFC voltages diverged due to microbial limitations at increasing currents With time, the initial microbial community decreased in diversity and Gram-positive species became dominant The shift of the microbial community accompanied a tripling of the short time power output of the individual MFCs from 73 W m(-3) to 275 W m(-3), a decrease of the mass transfer limitations and a lowering of the MFC internal resistance from 65 +/- 10 to 39 +/- 05 omega This study demonstrates a clear relation between the electrochemical performance and the microbial composition of MFCs and further substantiates the potential to generate useful energy by means of MFCs