Recherches en série diazépine-1,4 et triazépine-1,2,4. XV. Syntlièse d'halogéno-3(7)-s-triazolo[4,3-b] triazépinones

Halogenation of s-triazolo[4,3-b]triazepinones gas been accomplished by several methods. According to the agents used it has been possible to halogenate the triazepine ring (C-7 carbon) or (and) the triazole ring (C-3 carbon). Thus eighteen halogeno triazolotriazepines have been synthesized and their structures established from the spectral data.     

Liquid sheet disintegration at high pressure: An experimental approach

The primary atomization was studied in a 300 μm thickness water sheet, generated by a planar airblast atomizer. The research novelty consisted in increasing the airflow absolute pressure from atmospheric conditions to 6 bar. The experimental techniques employed included Oscillometry by Laser Intensity Reflexion (ORIL), Laser Doppler Velocimetry (LDV) and flow visualization by fast video camera. The atomization mechanisms, described in the literature at atmospheric environments, were observed at high pressure conditions, for a constant momentum flux ratio. Furthermore, a new atomization mechanism was observed at high values of this ratio. Finally, dimensionless relations have been proposed for the global oscillation frequency, minimum air oscillation velocity, break-up distance and transversal wavelength. To cite this article: V.G. Fernandez et al., C. R. Mecanique 337 (2009).     

Continuous thermodynamics for droplet vaporization: Comparison between Gamma-PDF model and QMoM

The Continuous Thermodynamics Model (CTM) (Cotterman et al., 1985) is a suitable method to reduce computational cost of multi-component vaporization models. The droplet composition is described by a probability density function (PDF) rather than tens of components in the classical Discrete Component Model (DCM). In the first CTM method developed for this application, the PDF was assumed to be a Γ-function (Hallett, 2000), but some problems had appeared in the case of vapor condensation at the droplet surface (Harstadt et al., 2003). The method put forward in this article, the Quadrature Method of Moments (QMoM), enables one to avoid any assumption on the PDF mathematical form. Following Lage who has developed this method for phase equilibria (Lage, 2007), this article widens the scope of QMoM to the modelling of multi-component droplet vaporization. The different CTM approaches are presented in the first part and the results obtained for a vapor condensation test case are then compared and analysed to illustrate improvements made by QMoM. To cite this article: C. Laurent et al., C. R. Mecanique 337 (2009).     

Synthesis of New Functionalized Cyclic Dipeptide

An efficient method has been developed for the synthesis of the functionalized cyclic dipeptide 6. The key step involves cyclisation of the linear dipeptide prepared by coupling a suitably protected β-amino acid with N-benzyl-t-butylglycinate.     

Diastereoselective Synthesis of Glycos-3-yl-α-amino Easters

We report here the diastereoselective synthesis of (2S, 3′R)-(α-D-allofuranos-3-yl) t-butyl glycinate by the condensation of a glycine enolate on the carbonyl function of α-D-ribohexofuranos-3-ulose 2.     

Major groove substituents and polymerase recognition of a class of predominantly hydrophobic unnatural base pairs

Expansion of the genetic alphabet with an unnatural base pair is a long‐standing goal of synthetic biology. We have developed a class of unnatural base pairs, formed between d 5SICS and analogues of d MMO2 that are efficiently and selectively replicated by the Klenow fragment (Kf) DNA polymerase. In an effort to further characterize and optimize replication, we report the synthesis of five new d MMO2 analogues bearing different substituents designed to be oriented into the developing major groove and an analysis of their insertion opposite d 5SICS by Kf and Thermus aquaticus DNA polymerase I (Taq). We also expand the analysis of the previously optimized pair, d NaM –d 5SICS , to include replication by Taq. Finally, the efficiency and fidelity of PCR amplification of the base pairs by Taq or Deep Vent polymerases was examined. The resulting structure–activity relationship data suggest that the major determinants of efficient replication are the minimization of desolvation effects and the introduction of favorable hydrophobic packing, and that Taq is more sensitive than Kf to structural changes. In addition, we identify an analogue (d NMO1 ) that is a better partner for d 5SICS than any of the previously identified d MMO2 analogues with the exception of d NaM . We also found that d NaM –d 5SICS is replicated by both Kf and Taq with rates approaching those of a natural base pair.     

Dynamic behavior of the circular membrane of an electrostatic microphone: effect of holes in the backing electrode

Today, several applications require using electrostatic microphones in environments and/or in frequency ranges, which are significantly different from those they were designed for. When low uncertainties on the behavior of acoustic fields, generated or measured by these transducers, are required, the displacement field of the diaphragm of the transducers (which can be highly nonuniform in the highest frequency range) must be characterized with an appropriate accuracy. An analytical approach, which leads to results depending on the location of the holes in the backing electrode (i.e., depending on the azimuthal coordinate) not available until now (regarding the displacement field of the membrane in the highest frequency range, up to 100 kHz), is presented here. The holes and the slit surrounding the electrode are considered as localized sources described by their volume velocity in the propagation equation governing the pressure field in the air gap (not by nonuniform boundary conditions on the surface of the backing electrode as usual). Experimental results, obtained from measurements of the displacement field of the membrane using a laser scanning vibrometer, are presented and compared to the theoretical results.     

Regioselective Synthesis of New Triheterocyclic Compounds from 1,4-Benzodiazepine

As part of our program on the synthesis of new heterocyclic compounds, we report here a one-step synthesis of [1,2,4]triazolo[4,3-d][1,4]benzodiazepine 3 and [1,2,4]oxadiazolo[4,5-d][1,4]benzodiazepine 5 by 1,3-dipolar cycloaddition of nitrilimines and nitrile oxides with 1,4-benzodiazepines 1.