Search results for " Formation"

Theoretical study on the molecular mechanism of the [5 + 2] vs. [4 + 2] cyclization mediated by Lewis acid in the quinone system

2013

[EN] The thermal and Lewis acid (LA) catalyzed cyclizations of quinone 1 involved in the synthesis of Colombiasin A and Elipsaterosin B have been theoretically studied using DFT methods at the B3LYP/6-311G(d,p) computational level. B3LYP calculations suggest that the formal endo [4 + 2] cycloadduct allowing the synthesis of Colombiasin A is preferentially formed under thermal conditions, while in the presence of the BF3 LA catalyst the formal [5 + 2] cycloadduct is seen, allowing the synthesis of Elipsaterosin B. The BF3 LA catalyst not only accelerates the nucleophilic attack on the C2 carbon of the quinone framework through a more polar C-C bond formation, but also provokes a different el…

HEAT: High accuracy extrapolated ab initio thermochemistry.

2004

A theoretical model chemistry designed to achieve high accuracy for enthalpies of formation of atoms and small molecules is described. This approach is entirely independent of experimental data and contains no empirical scaling factors, and includes a treatment of electron correlation up to the full coupled-cluster singles, doubles, triples and quadruples approach. Energies are further augmented by anharmonic zero-point vibrational energies, a scalar relativistic correction, first-order spin-orbit coupling, and the diagonal Born-Oppenheimer correction. The accuracy of the approach is assessed by several means. Enthalpies of formation (at 0 K) calculated for a test suite of 31 atoms and mole…

Disruption of apical-basal polarity of human embryonic stem cells enhances hematoendothelial differentiation

2007

Abstract During murine development, the formation of tight junctions and acquisition of polarity are associated with allocation of the blastomeres on the outer surface of the embryo to the trophoblast lineage, whereas the absence of polarization directs cells to the inner cell mass. Here, we report the results of ultrastructural analyses that suggest a similar link between polarization and cell fate in human embryos. In contrast, the five human embryonic stem cell (hESC) lines displayed apical-basal, epithelial-type polarity with electron-dense tight junctions, apical microvilli, and asymmetric distribution of organelles. Consistent with these findings, molecules that are components of tigh…

Rat fetuin: distribution of protein and mRNA in embryonic and neonatal rat tissues

1998

Fetuin is a serum protein widely distributed in the animal kingdom and found in all mammalian species so far investigated. It is mainly a fetal protein, in the sense that the highest concentrations are found in serum and body fluids of embryos and fetuses. In order to elucidate possible biological functions of fetuin, we have studied its synthesis and distribution during the prenatal development of the rat with immunohistochemistry and in situ hybridization. We have isolated fetuin from rat serum and produced an antibody against this protein. In situ hybridization was performed using a 375-nucleotides-long digoxigenin-labeled riboprobe. Fetuin was unevenly distributed in all organ systems d…

Bourgogne, l'entrée des jeunes dans la vie active

1983

Dans quelles conditions les jeunes, sorties à différents niveaux du système éducatif, vont-ils pouvoir s'insérer dans le monde du travail, en Bourgogne ? Dans quels secteurs d'activité se retrouvent ces débutants après leur scolarité ? Par quels emplois ? Dans le système scolaire, il existe une différenciation marquée entre les filières menant aux différents baccalauréats, entre l'enseignement général et l'enseignement technique, entre les spécialités industrielles de CAP ou tertiaires de BEP, entre les classes d'enseignement général et les classes pré-professionnelles ... Cette hiérarchisation omniprésente, liée à l'orientation des élèves, influe sur les sorties des jeunes à différents niv…

Genre et données longitudinales

2004

Plusieurs grands thèmes sont abordés : le marché du travail en Europe, les femmes et les entreprises, les temps modernes de l'emploi féminin, l'insertion professionnelle, les politiques de formation-insertion, l'articulation entre travail, famille et carrière, les comportements individuels dans le système éducatif et les pratiques culturelles ou sportives.

Content and Process of Study, Competencies Upon Graduation and Employment

2007

The authors identify the extent to which content and porcess o higher education shape the competences upon graduation and the subsequent employment.

Links between knowledge and work and appropriate employment

2007

07050; The paper analyses the professional success of graduates in terms of knowledge used on the job and links between educational attainments and position.

2020

Objective: The suggested link between major depression disorder (MDD) and blood–brain barrier (BBB) alterations supports an impact on the neurovascular unit in this disease condition. Here we inves...

Terpenoid treatment in osteoporosis: this is where we have come in research.

2021

Lower bone resistance to load is due to the imbalance of bone homeostasis, where excessive bone resorption, compared with bone formation, determines a progressive osteopenia, leading to a high risk of fractures and consequent pain and functional limitations. Terpenoids, with their activities against bone resorption, have recently received increased attention from researchers. They are potentially more suitable for long-term use compared with traditional therapeutics. In this review of the literature of the past 5 years, we provide comprehensive information on terpenoids, with their anti-osteoporotic effects, highlighting molecular mechanisms that are often in epigenetic key and a possible p…