Search results for "31"
showing 10 items of 4401 documents
Diastereoselective Synthesis of Dialkylated Bis(phosphino)ferrocenes: Their Use in Promoting Silver-Mediated Nucleophilic Fluorination of Chloroquino…
2017
International audience; The diastereoselective synthesis of dialkylated ferrocenyl bis(phosphane)s bearing aryl, alkyl, and hetero- or polycyclic substituents on the phosphino groups is reported, together with their characterization in the solid state by X-ray structure analysis and in solution by multinuclear NMR spectroscopy. Introduction of various alkyl groups on the ferrocene backbone, namely, tert-butyl, isopropyl, and trimethylsilyl, has a significant influence on the stereoselectivity of the ensuing lithiation/phosphination reactions. Only the introduction of the tert-butyl groups ensures both a high yield and perfect diastereoselectivity, which leads to the exclusive formation of t…
Efficient Nucleophilic Degradation of an Organophosphorus Pesticide “Diazinon” Mediated by Green Solvents and Microwave Heating
2019
An efficient strategy for the degradation of organophosphate pesticide Diazinon was investigated. In this work, ionic liquids, bio-based solvents, and two conventional organic solvents were used as reaction media. Kinetics studies by means of half-life (t1/2,h) were followed by 31P NMR and the products analyzed by GC-MS, HPLC-MS and NMR techniques. These results have shown that t1/2 values in ionic liquids were the lowest and also they were able to activate two electrophilic centers in Diazinon, whilst degradation in bio-based solvents occurred slowly by only an aromatic pathway. In addition, a study to estimate the influence of green activation techniques was carried out by using Ultrasoun…
Associations of nutrition and body composition with cardiovascular disease risk factors in soldiers during a 6-month deployment
2020
Objectives This observational follow-up study investigated the associations of nutrition and body composition with cardiovascular disease (CVD) risk factors, including pro-inflammatory biomarkers, in soldiers during a 6-month deployment. Material and Methods Thirty-five male soldiers were assessed at months 0, 3 and 6, and their parameters, i.e., M±SD, were as follows: age 30.0±8.7 years, height 179±6 cm, and BMI 24.2±2.5 kg/m 2 . Three-day food diaries were used for monitoring macronutrient intake. Body composition was estimated using bioimpedance. Fasting blood samples for lipids and pro-inflammatory biomarkers were collected, and blood pressure measurements were performed. Results Carboh…
Microscopic Origins of the Anomalous Melting Behavior of Sodium under High Pressure
2012
X-ray diffraction experiments have shown that sodium exhibits a dramatic pressure-induced drop in melting temperature, which extends from 1000 K at ~30 GPa to as low as room temperature at ~120 GPa. Despite significant theoretical effort to understand the anomalous melting, its origins are still debated. In this work, we reconstruct the sodium phase diagram by using an ab initio quality neural-network potential. Furthermore, we demonstrate that the reentrant behavior results from the screening of interionic interactions by conduction electrons, which at high pressure induces a softening in the short-range repulsion.
Real-space multiple scattering method for angle-resolved photoemission and valence-band photoelectron diffraction and its application to Cu(111)
2011
Abstract: A computational method is presented for angle-resolved photoemission spectra (ARPES) and photoelectron diffraction (PED) in the ultraviolet regime. The one-step model is employed and both initial valence and final continuum states are calculated using the finite-cluster, real-space multiple scattering method. Thereby the approach is versatile and provides a natural link to core-level PED. The method is applied to the Cu(111) valence band and good agreement with experiment is found for both ARPES spectra and PED patterns. When the PED patterns are integrated over a filled band of a single-orbital symmetry, such as Cu-3d, we show, both numerically and analytically, that the exact th…
What a Friend We Have in Facebook : Norwegian Christian Churches’ Use of Social Media
2021
This study examines how Christian churches in Norway use social media. The key finding is that the churches do not take extensive advantage of the opportunities for two-way communication offered by the platforms, but primarily use their social media channels to promote church activities or broadcast content without inviting a dialogue. Based on the churches’ own stated appreciation for building relationships, as well as existing research from media and communication studies, media and religion studies, and studies within strategic communication, this article argues for a stronger focus on the ritual and relational aspects of online communication from the church organizations. Pais Open Acce…
Graduate employment and the returns to higher education in Africa
2013
http://cemapre.iseg.utl.pt/educonf/2e3/files/submissions_to_web/Barounia%20Mahdi_Broeckeb%20%20Stijn.docx; In this paper, we estimate the return to higher education for 12 African countries using recent data and a variety of methods. Importantly, one of our methods adjusts for the effect of higher education on the rate of joblessness, which is substantial in most African countries, and particularly for women. Our results confirm that Mincerian coefficients cannot be interpreted as a true rate of return, and that the latter (even after taking into account the employment effect) is considerably lower than what has previously been suggested in the literature (less than half). For Sub-Saharan A…
Time Evolution of Partial Discharges in a Dielectric Subjected to the DC Periodic Voltage
2022
Partial discharge (PD) detection can be considered one of the most useful tools for assessing the insulation conditions of the power apparatus in high-voltage systems. Under AC conditions, this analysis is widely employed in online and offline tests, such as type tests or commissioning, and can be carried out by applying the phase-resolved PD (PRPD) method, since the patterns can give information about the defect classification. Under DC voltages, the classic pattern recognition method cannot be performed, and the measurements show complexities related to the nature of the phenomena. For this reason, to date, a standard for PD measurements under DC does not exist. In previous papers, a new …
Perron's method for the porous medium equation
2016
O. Perron introduced his celebrated method for the Dirichlet problem for harmonic functions in 1923. The method produces two solution candidates for given boundary values, an upper solution and a lower solution. A central issue is then to determine when the two solutions are actually the same function. The classical result in this direction is Wiener’s resolutivity theorem: the upper and lower solutions coincide for all continuous boundary values. We discuss the resolutivity theorem and the related notions for the porous medium equation ut −∆u = 0
Combinations of discourse markers with repairs and repetitions in English, French and Spanish
2020
Abstract Discourse markers have a central role in planning and repairing processes of speech production. They relate with fluency and disfluency phenomena such as pauses, repetitions and reformulations. Their polyfunctionality is challenging and few form-function mappings are stable cross-linguistically. This study combines a functional and a structural approach to discourse markers and their combination with and within repetitions and self-repairs in native English, French and Spanish, in order to establish the inter-relation between these three fluency-related devices and to find potentially universal patterns of use. Qualitative coding and quantitative analyses of categories of markers a…