Search results for "LIMIT"
showing 10 items of 2826 documents
DC polarographic reduction of chloroguanide hydrochloride.
1984
Chloroguanide hydrochloride, an antimalarial drug, shows one well-defined DC polarographic wave in Britton-Robinson buffered media. In the pH range 3–9 the observed reduction wave is related to the reduction of the two azomethine centers on the monoprotonated biguanide group (BH+). The effects of pH and other experimental variables on the limiting current and half-wave potentials as well as the reduction mechanism are discussed.
Durée et catastrophe. Régimes temporels et conflits écologiques à l’heure de la globalisation de l’environnement
2020
Elaborating from anthropology of nature and semiotic of culture, the work aims to illustrate that every ecological crisis is, also, a temporality crisis. In order to do so, it compares different visions of future – and, therefore, of the present of the enunciator – that shape international environmental crisis between ’60 and ’70. The first, insisting on risks, comes from Massachusetts Institute of Technology, advising about the Limits to Growth; the second, insisting on risk normalization, comes from UN first Earth Summit; both discourses are registered in reports published in 1972 and read worldwide. The analysis shows that while the MIT report successfully points the temporality crisis r…
Perception of Political Leadership in Local Governments in Latvia
2018
Theme of the paper is political leadership in local governments in Latvia. The work uses secondary data analysis and case studies. The aim of the study is to find out what kind of role does the chairperson of the municipality have as a political leader and what kinds of factors are influencing him/her. The results revealed that formally the chairperson of the municipality has no decisive influence on the municipality and that both types of factors (internal and external) interact with each other limiting the political leader’s (chairperson’s of a municipality) freedom of action.
Prospects for combining chemical and biological methods for integrated environmental assessment
2009
Abstract Inherently interdisciplinary, environmental assessment applied to contamination is evolving rapidly, despite associated uncertainties in methodologies and data limitations. Mixtures of known and unknown pollutants can cause toxic effects in the environment. Besides deploying a chemicals-driven strategy for the ecological risk assessment of the pollutants, it is necessary to apply and to explore biological strategies. Consequently, bioassays, biosensors and effect-directed analysis (EDA) to identify pollutants responsible of particular effects have become increasingly important. We give a broad overview of how to assess biological monitoring of ecosystems and chemical monitoring of …
Improving the prediction of air pollution peak episodes generated by urban transport networks
2016
Abstract This paper illustrates the early results of ongoing research developing novel methods to analyse and simulate the relationship between trasport-related air pollutant concentrations and easily accessible explanatory variables. The final scope is to integrate the new models in traditional traffic management support systems for a sustainable mobility of road vehicles in urban areas. This first stage concerns the relationship between the hourly mean concentration of nitrogen dioxide (NO2) and explanatory factors reflecting the NO2 mean level one hour back, along with traffic and weather conditions. Particular attention is given to the prediction of pollution peaks, defined as exceedanc…
Guidelines for alkylphenols estimation as alkylphenol polyethoxylates pollution indicator in wastewater treatment plant effluents
2013
A solid-phase microextraction coupled with a gas chromatography-mass spectrometry method has been developed for the estimation of technical nonylphenol in the presence of other endocrine disruptors, belonging to different chemical families. The profile of the technical nonylphenol found in real samples was tested, and, given that it was similar to that provided for the standard used, reliable results were obtainable. Endocrine disruptors such as 4-n-nonylphenol, bisphenol A and 4-tert-octylphenol were simultaneously analysed. The best conditions achieved enabled the analysis of all analytes using a sample volume of 15 mL or even only 300 μL. Using such a low sample volume reduced the filtra…
Wave Energy Assessment and Performance evaluation in Mediterranean Sea
2020
The paper proposes a revolutionary device for the utilization of a new entry of renewable energy sources: sea wave. This technology is based on linear generators, able to converts directly a linear motion into electrical output, limiting to minimum the chain of energy conversion. A preliminary feasibility assessment considers a case study applied in Lampedusa, a small island in the Mediterranean Sea. Economic and environmental evaluations are here reported.
Development of pipette tip-based poly(methacrylic acid-co-ethylene glycol dimethacrylate) monolith for the extraction of drugs of abuse from oral flu…
2019
Abstract In this work, a monolithic polymer based on poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MAA-co-EDMA) was prepared inside 200 μL pipette tips for the extraction of drug of abuse from oral fluid samples. After an appropriate surface tip modification, several polymerization mixtures with different monomer/cross-linker ratios, and percentage of porogen were studied. The most appropriate monolith to easily flow organic solvents and oral fluid samples was prepared with a MAA/EDMA ratio of 8:92 wt/wt and dodecanol containing 10 wt% toluene, as porogenic solvent. Parameters affecting the extraction procedure were evaluated and the monolith was characterized in terms of bindin…
Polymorphic domains in monolayers of isomeric triple-chain phospholipids
1991
Monolayers of two isomeric branched chain phosphatidyl cholines at the air/water interface have been studied by means of fluorescence microscopy. The lipids differ in the position of the branched chain at the glycerol backbone and carry three chains per headgroup of almost equal length. Most qualitative features of the compression isotherms are similar except a difference of 4 A2/molecule in the minimum molecular area at high lateral pressures. This indicates a more condensed solid phase of compound C2 and is also reflected in the shapes of domains observed in the LE/LC phase coexistence range: domains with sharp edges and a mostly hexagonal shape are formed. On the other hand, the compound…
The application of the supported liquid membrane and molecularly imprinted polymers as solid acceptor phase for selective extraction of biochanin A f…
2018
An efficient sample clean-up and preconcentration procedure for phytoestrogens analysis in urine has been developed. It was based on a combination of solid phase extraction with hollow-fiber supported liquid membrane and molecularly imprinted beads (MIPs-HF-SLM-SPE). The molecularly imprinted polymers (MIPs) were synthesized by precipitation polymerization technique with biochanin A (BCA) as a template, giving narrowly dispersed microspheres with a regular shape. As the functional monomer, (dimethylamino)ethyl methacrylate (-DEM) turned out to be better than methacrylic acid (MAA) to get the best-imprinted effects. The MIPs used as sorbents in the MIPs-HF-SLM-SPE extraction process exhibite…