Conservatoire national des arts et métiers

About: Conservatoire national des arts et métiers is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Orthogonal frequency-division multiplexing. The organization has 3573 authors who have published 7127 publications receiving 141430 citations. The organization is also known as: CNAM & Conservatoire des arts et métiers.

Human liver S9 fractions: metabolism of dehydroepiandrosterone, epiandrosterone, and related 7-hydroxylated derivatives.

Abstract: Dehydroepiandrosterone (DHEA) and 3β-hydroxy-5α-androstan-17-one (epiandrosterone, EpiA) are both precursors for 7α- and 7β-hydroxylated metabolites in the human brain. These 7-hydroxylated derivatives were shown to exert anti-glucocorticoid and neuroprotective effects. When these steroids are administered per os to humans, the first organ encountered is the liver, where extensive metabolism takes place. The objective of this work was to assess the cofactor dependence and metabolism of DHEA, EpiA, and their 7-hydroxylated derivatives in S9 fractions of human liver, using a radiolabeled steroid substrate for quantification and gas chromatography-mass spectrometry for identification. The best transformation yields were obtained with NADPH and were larger in female than in male. Results showed that both DHEA and EpiA mainly transformed into their 17β-hydroxylated derivatives, 7- or 16α-hydroxylated metabolites under NAD(P)H conditions, and 5α-androstane-3,17-dione for EpiA under NAD(P)+ conditions. In turn, 7α-hydroxy-DHEA and 7β-hydroxy-DHEA were partly transformed into each other via a 7-oxo-DHEA intermediate and were reduced into the 17β-hydroxy derivative, respectively. The same type of transformations occurred for 7α-hydroxy-EpiA and 7β-hydroxy-EpiA, except that no 7-oxo-EpiA intermediate was obtained. These findings determine the presence of enzymes responsible for the 7α- and 16α-hydroxylation in the human liver, the 11β-hydroxysteroid dehydrogenase type 1 responsible for the oxidoreduction of the 7-hydroxylated substrates, and the 17β-hydroxysteroid dehydrogenase responsible for the reduction of 17-oxo-steroids into 17β-hydroxysteroids.

Applying a Virtual Reality Platform in Environmental Chemistry Education To Conduct a Field Trip to an Overseas Site

Abstract: Field trips are a common activity for instructors to engage students and give them a first-hand understanding of a subject, especially in environmental chemistry. However, the planning and execution for a field trip is logistically challenging and demanding of human and material resources. Here, we demonstrate the conduct of a virtual overseas field trip for 74 students with the use of a web-based virtual reality (VR) application. From the feedback after the virtual field trip, students reported general receptiveness toward such use of VR technology.

A Century of Career Education: Review and Perspectives

Abstract: Although a textbook defining the principles of career education was published in Paris as early as 1957, career education did not actually develop in Europe until a quarter of a century later. Why it eventually came into its own can be explained by a number of factors, including an ideology promoting individual success, and changes in work organisation. The ends of career education practices are seldom defined: are they aimed at making workers more flexible?; are they meant to facilitate personal achievement?Although the theoretical foundations of these educational programs are often fragile and many of them have never been rigorously evaluated, those that have appear to have reached some of their educational objectives. Several factors should determine the future of career education: the evolution of the social function of school, changes in the role attributed to work in personal development, etc.

Synthesis and binding properties of calix[4]biscrown-based fluorescent molecular sensors for caesium or potassium ions

Abstract: The synthesis of two new fluorescent molecular sensors based on calix[4]biscrowns is reported. A dioxycoumarin fluorophore was incorporated into one of the crowns or into both crowns, leading to Calix-COU1 and Calix-COU2, respectively. The stability constants of the 1 ∶ 1 and 1 ∶ 2 complexes with potassium and caesium ions in ethanol or acetonitrile were measured. An anticooperative effect was observed when binding a second cation to the 1 ∶ 1 complex owing to electrostatic repulsion. The selectivity of Calix-COU1 in ethanol expressed as the ratio of the stability constants of the 1 ∶ 1 complexes was found to be about 4 × 104 for Cs+versus Na+ and greater than 500 for K+versus Na+. The origin of the cation-induced changes in the photophysical properties is discussed.

A high-efficiency and low-phase-noise 38-GHz pHEMT MMIC tripler

Abstract: Frequency translation circuits are key elements in communication systems. This paper presents a frequency tripler for 38-GHz short-range communication systems, designed using a pseudomorphic high electron-mobility field-effect transistor (pHEMT) technology. The successful first iteration monolithic microwave integrated circuit achieved a state-of-the-art output power of 3.1 dBm and a minimum conversion loss of 3.4 dB. The multiplier exhibits a conversion efficiency of 11% and average phase noise degradation at 10 and 100 kHz offset frequency from carrier of 9/spl plusmn/1 dB. Through a comprehensive study of the frequency multiplier, we demonstrate the optimum performance achieved under a class B mode of operation. To our knowledge, this is the first reported Ka-band single-stage frequency tripler based on pHEMT technology that has been fully characterized for phase noise degradation.