77 research outputs found
A clay-based formulation of the herbicide imazaquin containing exclusively the biologically active enantiomer
No full text8 páginas.-- 5 figuras.-- 2 tablas.-- 42 referencias.-- Supporting information may be found in the online version of this article in http://dx.doi.org/10.1002/ps.5296BACKGROUND: Imazaquin is a chiral herbicide which displays high mobility in soils. Like other imidazolinones, imazaquin is available for use only as racemic mixture of its enantiomers. In this work, several clay materials were assayed as adsorbents of imazaquin, and then the most suitable material was selected to prepare a clay-based slow release imazaquin nanoformulation containing exclusively the biologically active R-enantiomer. Next, laboratory experiments were conducted to illustrate the benefits of using the clay-based R-imazaquin formulation over the free (non-supported) racemic herbicide or the free pure R-imazaquin enantiomer regarding its leaching behavior and bioefficacy. RESULTS: The clay material selected as a carrier for R-imazaquin, hexadecyltrimethylammonium-saturated montmorillonite (SA-HDTMA), combined a high affinity for the herbicide and a high stability of the clay-herbicide adsorption complex. In a simulated scenario of high water input shortly after herbicide application, the clay-based R-imazaquin formulation displayed reduced leaching and increased bioefficacy compared to free racemic imazaquin and free R-imazaquin. CONCLUSION: The new clay-R-imazaquin formulation prepared, besides avoiding the environmental impact caused by the application of the less active S-enantiomer, reduced the herbicide leaching losses and prolonged the herbicidal activity, by increasing the residence time of the herbicide in the topsoil.This work was financed by the Spanish Ministry of Economy and Competitiveness (MINECO grants AGL2014-51897-R and AGL2017-82141-R), co-financed with FEDER-FSE funds. R.López-Cabeza also thanks MINECO for a pre-doctoral fellowship(grant BES-2012-059945) and B. Gámiz and I. Buerge for valuablesuggestions.Peer reviewe
Acesulfame: From Sugar Substitute to Wastewater Marker: Highlights of Analytical Chemistry in Switzerland
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Behavior of the Chiral Herbicide Imazamox in Soils: pH-Dependent, Enantioselective Degradation, Formation and Degradation of Several Chiral Metabolites
No full textMany pesticides show a pronounced
biphasic degradation in soil,
typically with a faster initial phase, followed by a slower decline.
For chiral compounds, a biphasic decline of the total concentration
may result from enantioselective degradation. In this study with the
chiral herbicide imazamox, biphasic degradation was observed in most
of the 18 soils investigated. In neutral soils, degradation was, in
fact, enantioselective with faster degradation of (+)-imazamox. In
slightly acidic soils, differences between enantiomers were not pronounced,
and in strongly acidic soils, degradation was again enantioselective,
but with reversed preference. Additional experiments with pure enantiomers
indicated no interconversion. Enantioselective degradation thus contributed
to the biphasic decline of the total concentration in certain soils.
However, this was not the only factor since degradation of the individual
enantiomers was biphasic in itself. In addition to the observed correlation
between enantioselectivity and pH, degradation was generally faster
in neutral than in acidic soils with half-lives ranging from only
2 to >120 days. Half-lives were also determined for two known metabolites
and a further chiral metabolite, the structure of which was characterized
by high resolution tandem mass spectrometry. As for the parent compound,
half-lives of the metabolites varied considerably in the different
soils
Three Women/Three Margins: Political Engagement and the Art of Claude Cahun, Jeanne Mammen, and Paraskeva Clark
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Is Creativity Lost in Translation? A discussion of the cultural underpinnings of creativity
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In the interrelated knowledge economy the fostering of creativity is key and as such is the focus of many government initiatives internationally. But is an international definition of creativity achievable or even desirable? Comparisons of different cultures’ propensities for creativity are problematic when we consider that most creativity research has taken place in Western cultures, with Western measures; and when creativity is defined as revolutionary this has often presented a dichotomous view of creativity that equates Westernisation with modernity. As a form of communication, creativity is open to mis- translation across cultures and despite some consensus between the West and Confucian heritage cultures on the desirable attributes to facilitate creativity, misunderstandings of creative practice based on cultural general tendencies such as individualism and collectivism remain. This paper reviews the literature on the development of concepts of creativity in Western and Confucian heritage cultures as well as reporting on a qualitative research study into the understandings and practice of creativity in a London art and design college in order to comment on the existence of a cross-cultural creativity divide and suggest that rather than be set against each other, creativity is enhanced by cultural creativity exchange and cross-cultural collaboration
Identification of reactive dyes in spent dyebaths and wastewater by capillary electrophoresis–mass spectrometry
No full textThe Chiral Herbicide Beflubutamid (II): Enantioselective Degradation and Enantiomerization in Soil, and Formation/Degradation of Chiral Metabolites
No full textAnalysis of anionic metallized azo and formazan dyes by capillary electrophoresis–mass spectrometry
No full textEntry Pathways of UV Filters from Sunscreens to Swiss Lakes: Highlights of Analytical Chemistry in Switzerland
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