Benzodioxines-1,4 disubstituées en position 2,3 par des groupements pharmacophores

2,3-Disubstituted 1,4-benzodioxines were prepared in six steps from 2-carboxy-1,4-benzodioxine. The α- and β-adrenergic blocking properties of these compounds were measured.     

A new synthetic route to 4,6-diarylpyridazinones and some of their derivatives

A novel approach to the titled ring system starting from conveniently available chalcones 1 is proposed. It involves a catalysed exchange of hydrogen cyanide between acetone cyanohydrin and 1 . The resulting γ-ketonitriles 2 give the expected 4,6-diarylpyridazinones 4 and 5 via hydrolysis and cyclisation by hydrazine. The action of phosphorus oxychloride on 5 followed by that of amines provides aminopyridazines 7 .     

Synthesis of new spirobenzazolines including a furo[3,4-b]pyran ring system

A series of 4,5-dihydrofuro[3,4-b]pyran-6-spiro-2′-benzazolines 3 were prepared by reaction of 4,4-dimethyl-2,6-dioxo-4,5-dihydrofuro[3,4-b]pyran 1 with o-phenylenediamine, o-aminophenol, o-aminothiophenol or their derivatives. Most of these compounds exhibited a significant analgesic activity.     

Synthesis and aldose reductase inhibitory activity of triazine derivatives possessing acetic acid group.

N-Acetic acid derivatives of 6-aryl-pyrazolo-triazin-4-ones were synthesized for evaluation as new aldose reductase inhibitors. The intrinsic activity of each compound was assessed by measuring the inhibition of enzymatic activity in an isolated pig lens enzyme preparation. All the prepared compounds exhibited a significant in vitro aldose reductase inhibitory effect (10(-6) M less than or equal to IC50 less than or equal to 10(-4) M). Furthermore, biological activity (log 1/IC50) for most of the data sets could be correlated directly to electronic and steric parameters. Finally, spatial configuration of the most active derivative 6c (IC50 = 2 x 10(-6) M) was compared with that of tolrestat and with pharmacophor requirements of the aldose reductase inhibitor site using a molecular modeling system.     

X-ray structural analysis of (1R,2R,4S,5S,8S)-2,8-bis(4-chlorophenyl)-4-(4-nitrophenyl)-1-aza-3,7-dioxabicyclo[3,3,0]octane

The configuration of the asymmetric atoms in the molecule of (1R,2R,4S,5S,8S)-2,8-bis(4-chlorophenyl)-4-(4-nitrophenyl)-1-aza-3,7-dioxabicyclo[3,3,0]octane has been determined using X-ray analysis. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 930-934, June, 2006.     

Thermodynamics of guest-induced structural transitions in hybrid organic-inorganic frameworks

We provide a general thermodynamic framework for the understanding of guest-induced structural transitions in hybrid organic-inorganic materials. The method is based on the analysis of experimental adsorption isotherms. It allows the determination of the free energy differences between host structures involved in guest-induced transitions, especially hard to obtain experimentally. We discuss the general case of adsorption in flexible materials and show how a few key quantities, such as pore volumes and adsorption affinities, entirely determine the phenomenology of adsorption, including the occurrence of structural transitions. On the basis of adsorption thermodynamics, we then propose a taxonomy of guest-induced structural phase transitions and the corresponding isotherms. In particular, we derive generic conditions for observing a double structural transition upon adsorption, often resulting in a two-step isotherm. Finally, we show the wide applicability and the robustness of the model through three case studies of topical hybrid organic-inorganic frameworks: the hysteretic hydrogen adsorption in Co(1,4-benzenedipyrazolate), the guest-dependent gate-opening in Cu(4,4'-bipyridine)(2,5-dihydroxybenzoate)2 and the CO2-induced "breathing" of hybrid material MIL-53.     

Velocity measurement of dc plasma jets based on arc root fluctuations

The axial component of the radial velocity distribution of a plasma flow generated by a dc plasma spray torch was measured by using a nonintrusive optical method, based on the propagation of the plasma jet luminosity fluctuations. In contrast to the simplicity of the experimental set-up, a special effort was made in the data processing, namely by using numerical techniques defined in the context of signal theory. Both centerline and radial profiles of the axial velocity were obtained for pure Ar and Ar–H₂ plasma flows. These experimental results were satisfactorily validated by calculating enthalpy and mass balances.Notation 1 refers to the reference signal - 2 refers to the shifted signal - a dimensionless adjustment factor - A ₁,_{f 1} values used for the estimation ofs ₁(t) energy spectrum - B ₁ frequency cutoff (Hz) - f frequency (Hz) - F ₁(f),F ₂(f) optimum low-pass filters - h mass enthalpy (J/kg) - h° enthalpy flowrate (J/s) - I(y) wavelength integrated radiation intensity - n ₁(t),F ₂(t) white noise - N ₁(t),N ₂() n ₁(t),n ₂(t)Fourier transforms - P _i probability - r radial coordinate - R plasma radius - s ₁(t),s ₂(t) signal components to be correlated - S ₁(f),S ₂(f) s ₁(t),s ₂(t) Fourier transforms - t time - T temperature (K) - , _i velocity (m/s) - x ₁(t),x ₂(t) recorded signals - X ₁(f),X ₂(f) x ₁(t),x ₂(t) Fourier transforms - x horizontal distance from the jet axis - y vertical distance from the jet axis - average velocity - standard deviation - z axial distance from the nozzle exit Greek Symbols dimensionless constant - r radial position uncertainty - velocity uncertainty - x width of the emission coefficient profile - z distance between the two sampling points - (r) radiative emission coefficient - time delay betweens ₁(t) ands ₂(t) - ₁ ^dg () x₁(t) autocorrelation function = x ₁(t)x ₁(t+)dt - ₁ ^dg (f) x₁(t) energy spectrum - _s1(), _s2() s ₁(t),s ₂(t) autocorrelation functions - _xt(f) s ₁(t) energy spectrum - ₁ ² , ₂ ² energy spectrum of white noisen ₁(t),n ₂(t) - ₁ time of correlation - ₁₂() cross-correlation function - coherence factor     

Open and closed-loop experiments to identify the separated flow dynamics of a thick turbulent boundary layer

Open and closed-loop flow control experiments were performed on the transient attachment and separation mechanisms of a thick turbulent boundary layer (TBL). Without actuation, the TBL is subjected to an adverse pressure gradient and separates downstream of a sharp variation in the wall geometry. Departing from a given geometry and steady operations of vortex generator actuators, the control objective was to attach the flow in the separated region with a minimum of injected fluid using adaptation of the closed-loop control. The large scale of the facility (i.e., δ = 20 cm upstream of separation) induces large time scales and large Reynolds numbers of the flow to be controlled. It is found to consequently induce large time scales of the separation/attachment mechanisms, making the dynamic closed-loop implementation easier. Open-loop tests were first performed to extract the adequate input/output variables for closed-loop implementations. The chosen input variable was the Duty Cycle, DC, which enables sending of a control action at least 10 times faster than the time scales of the attachment/separation process. The chosen output variable was the voltage signal from a hot-film probe located on the flap which characterizes the degree of separation. In open loop, both the large scale (i.e., large time scales) of the present facility (Carlier and Stanislas in J Fluid Mech 535(36):143–188, 2005) and the well-defined excitation (Braud and Dyment in Phys Fluids 24:047102, 2012) help to extract the different time scales involved and to identify the whole system (actuators, baseline flow and sensor). Three Reynolds numbers based on the momentum thickness of the boundary layer near the actuators and upstream of separation were investigated (Re _θ  = 7,500, 10,500 and 12,600) through variation of the free-stream velocity (U _∞ = 5, 8, 10 m/s). These three systems were found to behave like first-order linear systems, with coefficients that need to be adapted depending on the Reynolds number. From Re _θ  = 7,500 to Re _θ  = 12, 600, the time scale and static gain of the linear system needed to be almost doubled. A simple controller (Proportional-Integral) was implemented in closed-loop configuration, improving the reactivity of the system. Robustness was tested by varying the free-stream velocity. Closed-loop control based on a fixed reference was unsuccessful as it failed to account for the effect of the Reynolds number. This was successfully overcome by tracking a given state of the flow using a simple P controller to adapt the reference according to variations of Re. The P controller, acting on the DC variable, compensates the corresponding variations of VR (ratio between the free-stream and the jet exit velocity).     

Internal rotation and hyperfine coupling interaction in deuterated acetaldehyde

Theoretical and experimental investigations of the hyperfine structure of deuterated acetaldehyde (CD₃COH) are presented. The theoretical approach accounts for the large amplitude internal rotation of the CD₃ group. A hyperfine Hamiltonian, depending on the large amplitude torsional angle, is written taking into account quadrupole hyperfine coupling arising from the three deuterium atoms. Effective hyperfine coupling Hamiltonians are derived for A- and E-type rotation-torsion levels. In the former case, a very symmetrical operator arises in which the hyperfine coupling is the same for all three deuterium atoms. In the latter case the operators are less symmetrical. Hyperfine levels are calculated using symmetry adapted hyperfine wavefunctions in order to build total hyperfine-rotation-torsion wavefunctions satisfying the Pauli exclusion principle. The theoretical approach is used to carry out analyses of six hyperfine patterns which were recorded using a pulsed molecular beam Fourier transform microwave spectrometer. The experimental resolution of this apparatus allows us to resolve individual hyperfine components in many cases. The results of the analysis are consistent with deuterium atoms having an effective quadrupole coupling tensor which, except for appropriate rotations, is quite close to that in CH₃D.     

Thermodynamic Methods and Models to Study Flexible Metal–Organic Frameworks

Much attention has recently been focused on a fascinating subclass of metal‐organic frameworks that behave in a remarkable stimuli‐responsive fashion. These soft porous crystals feature dynamic crystalline frameworks displaying reversible, large‐amplitude structural deformations under external physical constraints such as temperature, electric field or gas exposure. The number of reported syntheses of such materials is rapidly growing and they are promising for practical applications, such as gas capture, purification and fluid separation. Herein, we summarize the recently developed thermodynamic tools that can help understand the process of fluid adsorption and fluid mixture coadsorption in these flexible nanoporous materials. These tools, which include both molecular simulation methods and analytical models, can help rationalize experimental results and predict adsorption properties over a wide range of thermodynamic conditions. A particular focus is given on how these methods can guide the experimental exploration of a large number of materials and working conditions (temperature, pressure, composition) to help design efficient processes relying on fluid adsorption in soft porous crystals.