Search results for "reparation"

Combined use of liquid chromatography triple quadrupole mass spectrometry and liquid chromatography quadrupole time-of-flight mass spectrometry in sy…

2012

As a suitable way for routine screening of pesticides and control of other organic contaminants in water, the combination of liquid chromatography triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS) and liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) has been applied to the analysis of 63 surface and waste water samples after conventional solid-phase extraction (SPE). The extracts were screened for 43 pesticides or degradation products by LC-QqQ-MS/MS achieving limits of detection (LOD) ranged from 0.04 to 2 ng L(-1). Of the 43 selected pesticides, 33 were detected in water samples. The ESI-QTOF MS instrument was run using two simultaneous acquisi…

Pre-service Science Teacher Preparation in Europe: Comparing Pre-service Teacher Preparation Programs in England, France, Finland and Cyprus

2015

A number of reports recently identify that the quality of science education in a number of European countries is lower than expected. One of the reasons for the apparent underachievement in this generally economically prosperous continent might be a pedagogy of science that lacks variety, or a pedagogy that is less engaging than other subjects. Given the diversity of European education systems, the purpose of this paper is to present aspects of four pre-service teacher preparation programs illustrating the similarities and differences that emerge. Specifically, we present the teacher preparation programs in England, Finland, France and Cyprus.

Tendencias actuales en la formación del profesorado de ciencias

2021

In the last few years, there has been a significant growth of interest in science teacher education. An analysis of recent science teacher education research is offered in this paper. This study answers the major question: What does research tell us about the recent trends in teacher preparation? We are beginning to understand that in the in-service or pre-service training is it very important to know the effects of: a) a limited content knowledge, b) the «commonsense» conceptions, behaviors and attitudes about different aspects of science teaching; c) the need of integration «knowledge -practice» in programs of teacher education and that; d) theses obstacles to didactic knowledge adquisiti…

Preservice teachers’ perspectives about coherence in their teacher education program

2019

While different countries have inherited different methods of teacher preparation, all countries aim for coherent programs, i.e. university-based courses are aligned with classroom practice. Yet, m...

Opportunities to Study, Practice, and Rehearse Teaching in Teacher Preparation: An International Perspective

2020

BackgroundAround the world, policy makers and teacher educators are paying increasing attention to how teacher candidates learn to study and enact teaching and to grounding preparation more deeply in teachers’ classroom practice. Evidence from the United States and the Netherlands suggests that efforts to tie preparation to practice may significantly impact pupils’ learning. However, the nature of teacher candidates’ opportunities to study, practice, and rehearse teaching remains underexplored, especially in international studies.PurposeOur research analyzes opportunities to study, practice, and rehearse teaching in teacher education coursework in five different programs in five countries. …

Exploration of new post-secondary mathematics teachers' experiences: preliminary results of a narrative inquiry

2018

International audience; This paper reports on a pilot study that has taken place during the winter semester of 2017, for a larger project whose goal is to understand the process of becoming a mathematics teacher at post-secondary level. With very few information from the literature on this process at this specific level, this pilot study acts as an exploration of the issues and reality the new teachers face. To do so, we conducted a narrative inquiry with three new post-secondary mathematics teachers who were interviewed on a regular basis during a semester. Those interviews provided an insight into the new teachers' experiences by pointing out themes that are relevant to them. We also came…

Multivariate Assessment of Procedures for Molecularly Imprinted Polymer Synthesis for Pesticides Determination in Environmental and Agricultural Samp…

2021

In the case of quantitative and qualitative analysis of pesticides in environmental and food samples, it is required to perform a sample pre-treatment process. It allows to minimalize the impact of interferences on the final results, as well as increase the recovery rate. Nowadays, apart from routinely employed sample preparation techniques such as solid-phase extraction (SPE) or solid-phase microextraction (SPME), the application of molecularly imprinted polymers (MIPs) is gaining greater popularity. It is mainly related to their physicochemical properties, sorption capacity and selectivity, thermo-mechanical resistance, as well as a wide range of polymerization techniques allowing to obta…

Influence of preparation conditions on the catalytic performance of mo/h-zsm-5 for methane dehydroaromatization

2021

[EN] Methane, the main component of natural gas, is an interesting source of chemicals and clean liquid fuels, and a promising alternative raw material to oil. Among the possible direct routes for methane conversion, its aromatization under non-oxidative conditions has received increasing attention, despite the low conversions obtained due to thermodynamic limitations, because of its high selectivity to benzene. Mo/H-ZSM-5, the first bifunctional zeolite-catalyst proposed for this reaction, is still considered as one of the most adequate and has been widely studied. Although the mono- or bifunctional nature of the MDA mechanism is still under debate, it is generally accepted that the Mo spe…

Temperature controller for brain slice chambers using a current sink output stage.

1985

The role of the dual nature of ionic liquids in the reversed-phase liquid chromatographic separation of basic drugs.

2010

The cationic nature of basic drugs gives rise to broad asymmetrical chromatographic peaks with conventional C18 columns and hydro-organic mixtures, due to the ionic interaction of the positively charged solutes with the free silanol groups on the alkyl-bonded reversed-phase packing. Ionic liquids (ILs) have recently attracted some attention to reduce this undesirable silanol activity. ILs are dual modifiers (with a cationic and anionic character), which means that both cation and anion can be adsorbed on the stationary phase, giving rise to interesting interactions with the anionic free silanols and the cationic basic drugs. A comparative study of the performance of four imidazolium-based I…