Search results for "Urea"
showing 10 items of 888 documents
Gas chromatographic behaviour of urea herbicides
2001
Gas chromatographic conditions for determining eight phenylurea (chlortoluron, diuron, fluometuron, isoproturon, linuron, metabenzthiazuron, metobromuron and monuron) and one sulfonylurea (chlorsulfuron) herbicides were assessed. Degradation products of the herbicides formed in the injector were used for identification. Most phenylureas formed their respective carbamic acid methyl esters, metabenzthiazuron formed an aminobenzothiazol and chlorsulfuron formed an aminotriazine plus a phenylsulfonamide. On-column injection of standards using a BP10 capillary column was evaluated to identify the chromatographic behaviour. Detection limits ranged from 0.05 ng for chlorsulfuron to 3 ng for monuro…
Determination of benzoylurea insecticides in food by pressurized liquid extraction and LC-MS
2010
A method based on pressurized liquid extraction and LC-MS/MS has been developed for determining nine benzoylureas (BUs) in fruit, vegetable, cereals, and animal products. Samples (5 g) were homogenized with diatomaceous earth and extracted in a 22 mL cell with 22 mL of ethyl acetate at 80 degrees C and 1500 psi. After solvent concentration and exchange to methanol, BUs were analyzed by LC-MS/MS using an IT mass analyzer, which achieved several transitions of precursor ions that increase selectivity providing identification. LOQs were between 0.002 and 0.01 mg/kg, which are equal or lower than maximum residue limits established by the Codex Alimentarius. Excellent linearity was achieved over…
Use of gold nanoparticle-coated sorbent materials for the selective preconcentration of sulfonylurea herbicides in water samples and determination by…
2012
Abstract Two new gold nanoparticle (NP) coated materials (silica supported on gold NP with and without ionic liquid) were synthesized for solid phase extraction of sulfonylurea herbicides (SUHs), such as bensulfuron-methyl (BSM), metsulfuron-methyl (MSM), pyrazosulfuron-methyl (PSM), thifensulfuron-methyl (TFM) and triasulfuron (TS), from water samples, followed by capillary liquid chromatography coupled to diode array detection (CLC–DAD). Several factors influencing the preconcentration efficiency of SUHs and its subsequent determination, such as pH of the sample, eluent and reusability of sorbents, have been investigated. Under the optimum conditions, the developed method allowed the dete…
Zum metabolismus von dialkyldithiocarbamaten
1974
Abstract Metabolism dialkyldithiocarbamates. I. Determination of amines using a reaction with isocyanates followed by gas chromatographic identification of the urea derivatives formed. N,N′-Di- and N,N′,N′-trisubstituted areas, formed by the reaction of amines with isocyanates, e.g. tert. -butyl isocyanate or 3-trifluoromethylphenyl isocyanate, are useful derivatives for the gas chromatographic analysis of primary and secondary amines. The separation is carried out at temperatures between 70 and 130° on liquid phases such as silicone OV-101 and silicone OV-17. With nitrogen and electron capture detectors the detection limit is 10 10 g. Trace analysis of simple primary and secondary amines i…
Malebranche: el placer dinámico y ordenado
2021
La crítica señala a Pierre Nicole como el pensador que hizo la transición entre aquellos primeros moralistas de mediados del siglo xvii que condenaban el mundo terrenal, y adoptaban una actitud negativa del ser humano, y los moralistas de la primera mitad del siglo xviii, cuya visión moderna y mundana concebía al hombre bajo una perspectiva positiva. Este estudio pretende ubicar a Nicolas Malebranche como el otro pensador, quizá más en la sombra, quizá con un modo no tan explícito, que protagoniza dicha transición. Bajo el reinado de Luis XIV, el filósofo parisino, influenciado notablemente por San Agustín y Descartes, establece una psicología dinámica que le aleja del estático epicureísmo …
Algoritmo diagnóstico para la toma de decisiones quirúrgicas en cirugía ortognática
2019
El deseo de alcanzar la belleza es universal. En todas las culturas y épocas el ser humano ha buscado plasmar la belleza en sus obras de arte. En la actualidad los cirujanos la buscan a través de la cirugía. El estudio de la bibliografía referida a la cirugía ortognática y los análisis cefalométricos vigentes muestran, como objetivo principal, restablecer el equilibrio oclusal y solo en segundo plano estudian la repercusión estética de la intervención. Esta tesis nace de la necesidad de dar respuesta a la pregunta: ¿Existe un modelo de estética aceptado universalmente en la sociedad española? (en la tesis solo se estudia a la población española de origen caucásico) y en el caso en que la re…
The Role of Contextual Factors in the Influence of ICT on Street-Level Discretion
2017
Public service workers in the frontline have traditionally enjoyed a wide freedom to make decisions during policy implementation. Research shows that technology has both constraining and enabling effects on public service workers affecting their ability to exercise discretion. What remains unclear is under which circumstances discretion is influenced by technology. Using a case study approach and drawing on neo-institutional theory, this paper studies a court to identify contextual factors affecting the phenomenon. Findings show that technology has no unilateral effect on street-level discretion, and is found moderated by contextual factors such as the degree of social complexity in a case,…
From development to power relations and territorial governance: Increasing the leadership role of LEADER Local Action Groups in Spain
2015
Abstract The establishment of Local Action Groups (LAGs) within the framework of LEADER with the participation of public and private actors through a bottom–up approach (i.e., the empowerment of local society) and the management of local development strategies constitutes one of the major innovations in the field of rural policy in Spain. The protagonism of local society and the local management of development processes entail the introduction and experimentation of previously unknown mechanisms of territorial governance. However, the efficacy of this rhetoric has been seriously limited in its practical implementation, with difficulties conceiving truly integrated and multi-sectoral strateg…
Two Decades of Change in Spanish Higher Education
1999
The 1983 Reforms The current structure of higher education was established by the 1983 University Reform Act, which greatly revised the legal framework of Spanish universities. Formerly completely controlled by the central government, universities have gained in autonomy and now depend more on regional governments. The legal reforms also democratized the internal structure of universities. Power was transferred from the state bureaucracy to university-level governing bodies, including nonacademic staff and students, that have decision-making powers in matters concerning the institution and departments and in electing the rector, deans, and department heads.
Empreendedorismo, inovação e internacionalização: o papel moderador das instituições
2021
Abstract The favorable effects of innovation and internationalization on the development of the economies of countries have been prominent factors in multiple management studies. The objective of this document is to make a theoretical review of the studies contained in the ScienceDirect (Elsevier) and ResearchGate databases, to offer an integrating framework of those institutional factors in the countries that favor the positive spillover of these two strategic actions carried out by companies: innovation and internationalization. As a result, we observed that an institutional framework characterized by a simplification of bureaucratic administrative procedures to access the financial resou…