A new approach to 2,2-disubstituted chromenes and tetrahydroquinolines through intramolecular cyclization of chiral 3,4-epoxy alcohols

An efficient route to chiral chromene and tetrahydroquinoline ring models 3 and 4 was developed by means of the vanadium epoxidation of chiral homoallylic alcohols 12 and 19 followed by an intramolecular epoxide opening of 3,4-epoxy alcohols 14 and 20. The configuration of all compounds was confirmed using NMR analysis.     

Anionic fullerenes, calixarenes, coronenes, and pyrenes as activators of oligo/polyarginines in model membranes and live cells

We report that the efflux of 5(6)-carboxyfluorescein anions from neutral egg yolk phosphatidylcholine vesicles is mediated by oligo/polyarginines only in the presence of activating amphiphilic anions. Screening of anion activators reveals best synergism for amphiphilic carboxylates (fullerene > calix[4]arene approximately coronene > pyrene > calix[6]arene > alkyl), whereas amphiphilic sulfates show less satisfactory activation despite often lower effective concentrations. The analogous alcohols and one calix[4]arene diphosphate were inactive. These results are discussed in the context of a tentative anion carrier mechanism, where interactions with bilayer (interface-directed translocation) and carrier (arene-templated carboxylate-guanidinium pairing) contribute to activator efficiencies. Applied to HeLa cells, pyrenebutyrate is shown to significantly increase the uptake of a fluorescently labeled octaarginine in a concentration-dependent manner.     

Three of a Kind: Control of the Expression of Liver-Expressed Antimicrobial Peptide 2 (LEAP2) by the Endocannabinoidome and the Gut Microbiome

The endocannabinoidome (expanded endocannabinoid system, eCBome)-gut microbiome (mBIome) axis plays a fundamental role in the control of energy intake and processing. The liver-expressed antimicrobial peptide 2 (LEAP2) is a recently identified molecule acting as an antagonist of the ghrelin receptor and hence a potential effector of energy metabolism, also at the level of the gastrointestinal system. Here we investigated the role of the eCBome-gut mBIome axis in the control of the expression of LEAP2 in the liver and, particularly, the intestine. We confirm that the small intestine is a strong contributor to the circulating levels of LEAP2 in mice, and show that: (1) intestinal Leap2 expression is profoundly altered in the liver and small intestine of 13 week-old germ-free (GF) male mice, which also exhibit strong alterations in eCBome signaling; fecal microbiota transfer (FMT) from conventionally raised to GF mice completely restored normal Leap2 expression after 7 days from this procedure; in 13 week-old female GF mice no significant change was observed; (2) Leap2 expression in organoids prepared from the mouse duodenum is elevated by the endocannabinoid noladin ether, whereas in human Caco-2/15 epithelial intestinal cells it is elevated by PPARγ activation by rosiglitazone; (3) Leap2 expression is elevated in the ileum of mice with either high-fat diet—or genetic leptin signaling deficiency—(i.e., ob/ob and db/db mice) induced obesity. Based on these results, we propose that LEAP2 originating from the small intestine may represent a player in eCBome- and/or gut mBIome-mediated effects on food intake and energy metabolism.     

Swirl measurements in a motor cylinder

 The present article analyzes different definitions of the swirl number and their application to control the mixing process in the cylinder of direct injection diesel engines. We first of all discuss the origins of the existing methods used to control swirl, which are usually based on the presence of a stirring device, or rotometer, in the cylinder head. A new possibility is then proposed for determining the swirl number, based on equivalent angular velocity, and a comparison made of results obtained using the different techniques available for measuring swirl in motor cylinders. Received: 16 December 1997/Accepted: 18 May 1998     

Équations de Hamilton–Jacobi et inégalités entropiques généraliséesHamilton–Jacobi equations and inequalities for generalised entropies

We prove the equivalence between a general logarithmic Sobolev inequality and the hypercontractivity of a Hamilton–Jacobi equation. We also recover that this property imply a transportation inequality established by [5]. These results provide a natural generalization of the work performed in [3]. To cite this article: I. Gentil, F. Malrieu, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 437–440.     

Picosecond spectroscopy of pinacyanol (1,1′-diethyl2,2′-monocarbocyanine chloride)

Photobleaching and absorption recovery of the fundamental state of pinacyanol have been investigated in different solvents, using a single picosecond pulse. In a viscous solvent, glycerol, the recovery time constant is τ = (330 ± 30) ps which may be compared with the fluorescence lifetime τ = (302 ± 29) ps, as measured using a steak camera. In the lighter alcohols, methanol or isopropanol, the shorter recovery time constant τ < 10 ps indicates a very efficient non-radiative process, internal conversion between the two singlet states involved.     

Experimental evidence for a high-pressure isostructural phase transition in osmium

We have measured the isothermal equation of state (EOS) of osmium to 75 GPa under hydrostatic conditions at room temperature using angle-dispersive x-ray diffraction. A least-squares fit of this data using a third-order Birch-Murnaghan EOS yields an isothermal bulk modulus K0=411+/-6 GPa, showing osmium is more compressible than diamond. Most importantly, we have documented an anomaly in the compressibility around 25 GPa associated with a discontinuity in the first pressure derivative of the c/a ratio. This discontinuity plausibly arises from the collapse of the small hole-ellipsoid in the Fermi surface near the L point.     

Cryopreservation of Citrus madurensis embryonic axes encapsulation-dehydration

In this paper, we demonstrate that C. madurensis embryonic axes can withstand cryopreservation using the encapsulation-dehydration technique. Up to 57.5 % survival was achieved using a standard encapsulation-dehydration protocol, which included pregrowth of encapsulated axes for 16 h in medium containing 0.8 M sucrose + 1 M glycerol, desiccation of beads to around 30 % moisture content (fresh weight basis) followed by rapid freezing. A slightly higher survival percentage (65 %) was obtained using a modified encapsulation-dehydration protocol, which included pretreatment of axes with 2 M glycerol + 0.6 M sucrose for 1 h, concomitantly with their encapsulation in 3 % calcium alginate beads, followed by desiccation of the beads to around 30 % moisture content.     

Cryopreservation of Citrus aurantifolia seeds and embryonic axes using a desiccation protocol

The desiccation and freezing tolerance of seeds, with and without testas, and embryonic axes of Citrus aurantifolia were investigated. Seeds were desiccated with silica gel, under the laminar air flow cabinet or by placing them on a laboratory bench. Whatever the desiccation method employed, survival before and after cryopreservation was higher for seeds without testas. When freezing intact seeds, the highest survival percentage (41.3 %) was achieved after desiccation to 7.3 % moisture content (fresh weight basis) on the laboratory bench. Survival of seeds cryopreserved without testas could reach up to 85 % after desiccation under the laminar air flow cabinet or on the laboratory bench, corresponding to moisture contents of 7.1 and 4.5 %, respectively. After desiccation with silica gel, survival reached a maximum of 60.0 %, for a seed moisture content of 3.3 %. Survival of control embryonic axes was high (80-100 %) whatever the sucrose concentration in the preculture medium and the duration of the desiccation period. After cryopreservation, no survival was noted with embryonic axes, which had not been precultured nor desiccated. Survival of non-desiccated embryonic axes after cryopreservation increased progressively in line with increasing sucrose concentrations in the preculture medium, from 7.5 % with 0.1 M sucrose to 77.5 % with 0.7 M sucrose. Survival of desiccated and cryopreserved embryos was always high, whatever the preculture treatment and desiccation period, ranging from 55.8 % to 92.5 %.