Heat transfer between two nanoparticles through near field interaction

We introduce a thermal conductance by using the fluctuation-dissipation theorem to analyze the heat transfer between two nanoparticles separated by a submicron distance. Using either a molecular dynamics technique or a model based on the Coulomb interaction between fluctuating dipoles, we derive the thermal conductance. Both models agree for distances larger than a few diameters. For separation distances smaller than the particle diameter, we find a transition regime characterized by a thermal conductance larger than the contact conductance.     

LiInSe2 nanosecond optical parametric oscillator

Optical parametric oscillation using the new lithium selenoindate nonlinear crystal is reported for what is to our knowledge the first time. A 17 mm long, type II phase-matched sample is pumped by a 10 ns Nd:YAG laser. The minimum pump energy threshold is 3 mJ for a signal-resonant configuration. The signal and idler waves are tunable between 1.47 and 1.57 microm, and 3.3 and 3.78 microm, with a total output energy of 170 microJ corresponding to a 2.4% energy conversion at 8 mJ pump, only limited by the AR coatings damage. With optimized crystal quality and coatings, lithium selenoindate should show superior performance as compared with AgGaS(e)2 crystals, owing to its 4x larger thermal conductivity.     

An enantioselective access to 1-alkyl-1,2,3,4-tetrahydroisoquinolines. Application to a new synthesis of (-)-argemonine

Potassium ferricyanide oxidation of salt 1 gave isoquinolinone 7 whose treatment with Grignard reagents resulted in a high-yield formation of substituted isoquinolinium salts 5. The selectivity of the reduction of these salts to give derivatives 6 has been studied. Particularly good selectivities (82-84%) were observed when R is a benzylic group. On the basis of these results, a practical and enantioselective synthesis of the natural alkaloid (-)-argemonine is presented.     

The t+n+n system and 5H

The one-proton knockout channel from 6He (240 MeV/u) impinging on a carbon target has been investigated. The triton fragments originating from this channel were detected in coincidence with the two neutrons. A broad structure, peaked at 3 MeV above the t+2n threshold, is observed in the t+n+n-relative energy spectrum. It is shown that this structure is mainly due to a I(pi)=1/2(+) resonance as expected for the 5H ground state, and from the observed angular and energy correlations, being used for the first time in 5H studies, that the neutrons to a large extent occupy the p shell.     

Un analogue local du théorème de Harnack

Sans résumé     

Fragmentation of the chain in the mass spectra of the pyrrolidides of alkylcyclohexanecarboxylic acids

The electron impact mass spectra of the pyrrolidides of both the cis- and trans-octylcyclohexanecarboxylic acids show the structure of the aliphatic chain, despite the steric hindrance of a direct H transfer from the chain to the functional group.     

Synthesis of 3′-deoxy-3′-iminodiacetic acid and 3′-deoxy-3′-aminodiethanol thymidine analogues and NMR study of their complexation with boronic acids

The iminodiacetic acid and aminodiethanol moieties are known for their ability to generate with boronic acids bicyclic structures having a strong intramolecular NB coordination. We describe here the convergent synthesis of 3′-deoxy-3′-iminodiacetic acid and 3′-deoxy-3′-aminodiethanol thymidine analogues. The abilities of these compounds to form boronate complexes with aliphatic or aromatic boronic acids were established by 1D and 2D ¹H and ¹³C NMR. Moreover, conformational analysis of the newly synthesized compounds revealed a marked preference for an N-type sugar puckering.