A general route for the synthesis of pyrimido[4′,5′:4,5]thieno[2,3-c]pyridazine derivatives

Summary A facile synthesis of 8-substituted pyrimido[4,5:4,5]thieno[2,3-c]pyridazines (6a–i) has been accomplished. The sequence involves the ring closure of a heterocyclic aminonitrile precursor (3) after reaction with (dichloromethylene)-dimethylammonium chloride.

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Eine allgemeine Synthese von Pyrimido[4,5:4,5]thieno[2,3-c]pyridazin-Derivaten

Zusammenfassung Es wurde ein einfacher Syntheseweg für 8-substituierte Pyrimido[4,5:4,5]thieno-[2,3-c]pyridazine entwickelt. Die Reaktion verläuft über den Ringschluß eines heterocyclischen Aminonitrilvorläufers (3) nach Umsetzung mit Dichlormethylen-dimethylammoniumchlorid.

     

AnL p -theory for then-dimensional,stationary, compressible Navier-Stokes equations,and the incompressible limit for compressible fluids. The equilibrium solutions

In this paper we study the system (1.1), (1.3), which describes the stationary motion of a given amount of a compressible heat conducting, viscous fluid in a bounded domain ofR ⁿ, n2. Hereu(x) is the velocity field, (x) is the density of the fluid, (x) is the absolute temperature,f(x) andh(x) are the assigned external force field and heat sources per unit mass, andp(, ) is the pressure. In the physically significant case one hasg=0. We prove that for small data (f, g, h) there exists a unique solution (u, , ) of problem (1.1), (1.3)₁, in a neighborhood of (0,m, ₀); for arbitrarily large data the stationary solution does not exist in general (see Sect. 5). Moreover, we prove that (for barotropic flows) the stationary solution of the Navier-Stokes equations (1.8) is the incompressible limit of the stationary solutions of the compressible Navier-Stokes equations (1.7), as the Mach number becomes small. Finally, in Sect. 5 we will study the equilibrium solutions for system (4.1). For a more detailed explanation see the introduction.     

How relevant is the lack of reciprocity in pairwise comparisons? An experiment with AHP

We consider the 1-median problem with euclidean distances with uncertainty in the weights, expressed as possible changes within given bounds and a single budget constraint on the total cost of change. The upgrading (resp. downgrading) problem consists of minimizing (resp. maximizing) the optimal 1-median objective value over these weight changes. The upgrading problem is shown to belong to the family of continuous single facility location-allocation problems, whereas the downgrading problem reduces to a convex but highly non-differentiable optimization problem. Several structural properties of the optimal solution are proven for both problems, using novel planar partitions, the knapsack Voronoi diagrams, and lead to polynomial time solution algorithms.     

Digital pulse processing in Mössbauer spectroscopy

In this work we present some advances towards full digitization of the detection subsystem of a Mössbauer transmission spectrometer. We show how, using adequate instrumentation, preamplifier output of a proportional counter can be digitized with no deterioration in spectrum quality, avoiding the need of a shaping amplifier. A pipelined architecture is proposed for a digital processor, which constitutes a versatile platform for the development of pulse processing techniques. Requirements for minimization of the analog processing are considered and experimental results are presented.     

Optimization of headspace solid-phase microextraction for analysis of β-caryophyllene in a nanoemulsion dosage form prepared with copaiba (Copaifera multijuga Hayne) oil

Recent studies have shown the anti-inflammatory activity of Copaiba oils may be addressed to the high content of β-caryophyllene, the most common sesquiterpene detected, especially in the Copaifera multijuga Hayne species. In the present study, nanoemulsions were proposed as a delivery system for copaiba oil in view to treat locally inflamed skin. This article describes the optimization and validation of a stability-indicating SPME-GC method, for β-caryophyllene analysis in the nanoemulsions produced by high pressure homogenization. SPME methods are performed with PDMS (polydimethylsiloxane) fiber (100 μm). Three SPME parameters were evaluated by a three-level-three-factor Box–Behnken factorial design as potentially affecting the technique efficiency. According to the results obtained, the best conditions to extract β-caryophyllene were: (i) sampling temperature of 45 °C, (ii) sampling time of 20 min and (iii) no NaCl addition. Results coming from the forced degradation tests showed a reduction of β-caryophyllene peak area when both caryophyllene methanolic solution and nanoemulsions were exposed to acid hydrolysis, UV-A irradiation, oxidative (H₂O₂) and thermolitic (60 °C) conditions. Such reduction occurred in lower extent in the nanoemulsions, suggesting a protective effect of the formulation to β-caryophyllene content. Since no degradation products were detected in the same retention time of β-caryophyllene, the specificity of the method was demonstrated. The method was linear in the range of 0.14–0.68 μg mL⁻¹ of β-caryophyllene (r² > 0.999), and was also validated for precision (R.S.D. ≤ 5.0%), accuracy (97.85–101.87%) and robustness. Finally, the method was applied to quantification of β-caryophyllene content in the developed formulations.     

Topology optimization methods for guided flow – comparison of optimality criteria vs. phase-field method

Optimization of guided flow problems is an important task for industrial applications especially those with high Reynolds numbers. There exist several optimization methods to increase the energy efficiency of these problems. Different optimization methods are shown bei Klimetzek [1], Hinterberger [2] and Pingen [3]. In recent years the phase-field method has been shown to be an applicable method for different kinds of topology optimization [4, 5]. We present results of topology optimization methods with optimality criterion and by using a phase-field model in the area of guided fluid flow problems. The two methods aim on the same main target reducing the pressure drop between the inlet and outlet of the flow domain. The first method is based on local optimality criterion, preventing the backflow in the flow domain [1, 6, 7]. The second method is based on a phase field model, which describes a minimization problem and uses a specially constructed driving force to minimize the total energy of the system [4, 5]. We investigate the capabilities and limits of both methods and present examples of different resulting geometries. The initial configurations are prepared in a way that the same optimization problem is solved with both methods. We discuss these results regarding the shape of the improved flow geometry. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Asymptotics of shell eigenvalue problems

The asymptotic behaviour of the smallest eigenvalue in linear shell problems is studied, as the thickness parameter tends to zero. When pure bending is not inhibited, such a behaviour has been essentially studied by Sanchez-Palencia. When pure bending is inhibited, the situation is more complex and some information can be obtained by using the Real Interpolation Theory. In order to cover the widest range of mid-surface geometry and boundary conditions, an abstract approach has been followed. A result concerning the ratio between the bending and the total elastic energy is also announced. To cite this article: L. Beirão da Veiga, C. Lovadina, C. R. Acad. Sci. Paris, Ser. I 342 (2006).     

Modelling the size of red-colouring copper nanoclusters in archaeological glass beads

The origin of a red colour in ancient soda-lime glasses has been attributed either to the presence of both copper clusters and cuprous oxide or to copper alone. As a contribution to this question, a non-destructive X-ray absorption study at the [ _Cu]K-edge was undertaken on the red layer from a singular “rosette”-type archaeological glass bead dated as pre-XVII century. On comparing with data collected from metallic copper and the mineral cuprite, cubic Cu₂O, XANES spectra of the red glass are identical to the first. Theoretical modelling of Cu 1s XANES spectra was undertaken using the FEFF code based on a multiple scattering formalism. A hypothetical tetragonal structure was simulated for Cu₂O in order to remove the constraints arising from linear O–Cu–O bonds, unstable within the silica glass matrix, and an ideal body-centred array was considered on the basis of real metallic Cu–Cu distances in the metal. Calculations were performed for atom clusters of variable size within real and hypothetical structures. A spherical cluster of about 5 Å radius, capped by 24 copper atoms already provides a calculated Cu 1s XANES spectrum that compares well with data collected from the red glass. Post-edge details are noted in relation to the oxide, considering ionic states and effective valences of copper. The possibility of estimating the size of copper clusters through simulated structures is discussed.     

Magnetic and thermal Mössbauer effect scans: a new approach

Mössbauer transmission recorded at fixed photon energies as a function of a given physical parameter such as temperature, external field, etc. (Mössbauer scan), is being developed as a useful quantitative tool, complementary of Mössbauer spectroscopy. Scans are performed at selected energies, suitable for the observation of a given physical property or process. It is shown that one of main advantages of this approach is the higher speed at which the external physical parameter can be swept, which allows the recording of quasi-continuous experimental response functions as well as the study of processes which occur too fast to be followed by Mössbauer spectroscopy. The applications presented here are the determination of the temperature dependence of the ⁵⁷Fe hyperfine field in FeSn₂, the thermal evolution and nanocrystallization kinetics of amorphous Fe_73.5Si_13.5Cu₁Nb₃B₉ and the measurement of the dynamic response of Fe magnetic moments in nanocrystalline Fe₉₀Zr₇B₃ to an external ac field.