An efficient method for nonlinear aeroelasticy of slender wings

This paper aims the nonlinear aeroelastic analysis of slender wings using a nonlinear structural model coupled with the linear unsteady aerodynamic model. High aspect ratio and flexibility are the specific characteristic of this type of wings. Wing flexibility, coupled with long wingspan can lead to large deflections during normal flight operation of an aircraft; therefore, a wing in vertical/forward-afterward/torsional motion using a third-order form of nonlinear general flexible Euler–Bernoulli beam equations is used for structural modeling. Unsteady linear aerodynamic strip theory based on the Wagner function is used for determination of aerodynamic loading on the wing. Combining these two types of formulation yields nonlinear integro-differentials aeroelastic equations. Using the Galerkin’s method and a mode summation technique, the governing equations will be solved by introducing a numerical method without the need to adding any aerodynamic state space variables and the corresponding equations related to these variables of the problem. The obtained equations are solved to predict the aeroelastic response of the problem. The obtained results for a test case are compared with those of some other works and show a good agreement between results.     

Numerical modelling of film cooling with and without mist injection

Two-phase CFD calculations, using a Lagrangian model and commercial code Fluent 6.2.16, were employed to calculate the gas and droplet flows and film cooling effectiveness with and without mist on a flat plate. Two different three dimensional geometries are generated and the effects of the geometrical shape, size of droplets, mist concentration in the coolant flow and temperature of mainstream flow for different blowing ratios are studied. A cylindrical and laterally diffused hole with a streamwise angle of 30° and spanwise angle of 0° are used. The diameter of film cooling (d) hole, and the hole length to diameter ratio (L/d) for both of geometries are 10 mm and 4, respectively. Also the blowing ratio ranges from 1.0 to 2.0, and the mainstream Reynolds number based on the mainstream velocity and hole diameter (Re _d) is 6,219. The results are shown for different droplets diameters (1–10 μm), concentrations (1–5%) and mainstream temperatures (350–500 K). The centreline effectiveness and distribution of effectiveness on the surface of cooling wall are presented.     

Pressure Improvement on a Supercritical High-Lift Wing Using Simple and Modulated Pulse Jet Vortex Generator

In this paper, an experimental study, aimed at delaying flow separation on a high-lift device using a pulsed blowing excitation method, is reported. The main objective of this investigation was to evaluate a new pulsed jet generation strategy to enhance flow control performance. In these experiments, two types of signal waveform were implemented to produce the unsteady blowing; a simple square-wave excitation signal for the first case, and a burst modulated excitation signal for the second case. The signal modulation was the first time to be used for a fast-switching solenoid valve actuator. Another objective of this study was to evaluate a new arrangement of the jet exit slots, in the form of a vortex generator which was employed for the first time on the high-lift device. For this purpose, a NASA SC(2)-0714 airfoil with a single slotted flap was employed. The vortex generator jets emanated from the shoulder of the trailing-edge flap with excitation frequencies from 40 to 1000 Hz. Pressure distribution around the model and wake total pressure deficit were measured. The results indicated that ejection from vortex generator slot pairs was able to prevent flow separation completely in most conditions. These measurements revealed that the burst modulated excitation signal was accompanied by more aerodynamic improvements and less air consumption relative to the simple pulsed jet excitation signal. In the best flow control mode, the results showed about a 53% increase in the value of the suction pressure peak on the flap and a 38% decrease in drag with a reduction in total pressure loss.

     

Die Synthese von 3β-Acetoxy-24-aza-24-desoxa-xysmalogenin,. Partialsynthetische Versuche in der Reihe der Herzgifte. 12. Mitteilung,

Synthesis of 3β-acetoxy-24-aza-24-desoxa-xymalogenin Starting from the pregnenolone-derivative 1 we report the synthesis of the possibly cardiac-active compound 24-aza-24-desoxa-xysmalogenin 15 .     

Studies on the pitting corrosion of zinc in aqueous solutions II. Measurement of pitting corrosion currents operating under natural conditions

A simple experimental arrangement was applied for the measurement and the evaluation of pitting corrosion currents operating under natural conditions. The feasibility of the procedure was examined by using Zn as a test metal, K₂CrO₄, Na₂HPO₄ and Na₂WO₄ as inhibitors, and Cl^?, Br^? and I^? as pitting corrosion agents. Both the type and concentration of the inhibiting and corroding agents were varied in a programmed manner. In CrO₄^2? and HPO₄^2? solutions, the pitting corrosion currents started to flow after an induction period, which decreased with increase in the concentration of the attacking agent. In WO₄^2? solutions, on the other hand, initially high currents were recorded due to the reduction of the agent to soluble, non-inhibiting species.In all solutions tested the corrosion current reached steady-state values which depended on the type and concentration of both the inhibiting and the aggressive anions. When keeping the inhibitor concentration constant, the corrosion current varied with the concentration of the aggressor according to: log i_corr = a₁ + b₁ log c_agg On the other hand, in solutions of constant aggressor concentration, with varying inhibitor amounts, the relation was: log i_corr = a₂ ? b₂ log c_inh where a₁(a₂) and b₁(b₂) are constants.The two equations were derived theoretically on the basis of competitive adsorption of the two counteracting agents on the surface of the metal. Comparison between the experimental values of a and b, with the corresponding terms of the theoretical equations was made.The aggressivity of the three tested anions decreases in the order Cl^? > Br^? > I^?, whilst inhibition varied as CrO₄^2? > HPO₄^2? > WO₄^2?.     

Selective transport of silver ions through bulk liquid membrane using Victoria blue as carrier

Transport of Ag⁺ as Ag(CN)₂⁻ ions through a bulk liquid membrane is reported. The bulk liquid membrane used is a solution of Victoria blue (VB) in chloroform. The effects of pH of the source phase, cyanide concentration in the source phase, sodium hydroxide in the receiving phase, and VB concentration in the organic phase on the efficiency of the transport system were studied. The above system has a high selectivity for Ag⁺ and can selectively and efficiently transport Ag(CN)₂⁻ ion from aqueous solutions containing other cations such as alkali and alkaline earths, Zn²⁺, Pd²⁺, Cu²⁺, Cd²⁺,Hg²⁺, Co²⁺, Fe²⁺, Pb²⁺, Ni²⁺, and Al³⁺.     

Fabrication of a renewable syringe carbon paste electrode with a motor rotary blade and using for voltammetric measurement of dipyridamole

In this work, we fabricated a new renewable syringe carbon paste electrode (SCPE) equipped with a motor rotary cutting blade and used for voltammetric determination of dipyridamole (DIP) in aqueous solution, at room temperature. The cutter rotates by a small electrical motor and easily renews the surface of the carbon paste electrode by removing the spotty surface. Electrochemical performance of the constructed electrode was investigated with cyclic voltammetry (CV) and compared to some other previously reported works. The new sensor showed several advantages such as excellent repeatability, high stability, good sensitivity and easily surface renewable. The results indicated that the presence of methyltrioctyl ammonium chloride (MTOAC) could remarkably enhance the oxidation of DIP due to feasible electrical conductivity properties in a phosphate buffer solution. At optimum conditions for the new syringe CPE, the square wave voltammetry (SWV) was used to measure the concentration of DIP in a linear range of 0.08–30.0 µM and a detection limit of 0.02 µM was obtained after 100 s of accumulation time. The sensor was then tested for the simple, rapid and sensitive electrochemical determination of DIP in real samples such as pharmaceutical formulations.     

Improving of Anticancer Activity and Solubility of Cisplatin by Methylglycine and Methyl Amine Ligands Against Human Breast Adenocarcinoma Cell Line

Methylglycine, also known sarcosine, is dramatically used in drug molecules and its metal complexes can interact to DNA and also do cleavage. Hence, to study the influence of methylglycine ligand on biological behavior of metal complexes, two water-soluble platinum (II) complexes with the formula cis-[Pt(NH₃)₂(CH₃-gly)]NO₃ and cis-[Pt(NH₂-CH₃)₂(CH₃-gly)]NO₃ (where CH₃-gly is methylglycine) have been synthesized and characterized by spectroscopic methods, molar conductivity measurements, and elemental analyzes. The anticancer activity of synthesized complexes was tested against human breast adenocarcinoma cell line of MCF7 using MTT assay and results showed excellent anticancer activity with Cc₅₀ values of 126 and 292 μM after 24 h incubation time, for both complexes of cis-[Pt(NH₃)₂(CH₃gly)]NO₃ and cis-[Pt(NH₂-CH₃)₂(CH₃gly)]NO₃, respectively. Also, the interaction between Pt(II) complexes with calf thymus DNA was extensively studied by means of absorption spectroscopy, fluorescence titration spectra displacement with ethidium bromide (EtBr), and circular dichroism studied in Tris-buffer. The obtained spectroscopic results revealed that two complexes can bind to highly polymerized calf thymus DNA cooperatively and denature at micromolar concentrations. The fluorescence data indicate that quenching effect for cis-[Pt(NH₃)₂(CH₃gly)]NO₃ (K_sv?=?9.48 mM^?1) was higher than that of cis-[Pt(NH₂-CH₃)₂(CH₃gly)]NO₃ (K_sv?= 1.98 mM^?1). These results were also confirmed by circular dichrosim spectra. Consequently, docking data showed that cis-[Pt(NH₃)₂(CH₃gly)]NO₃ with more interaction energy binds on DNA via groove binding which is more compatible with experimental results.

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Graphical Abstract ? Two anticancer Pt(II) complexes, cis-[Pt(NH₃)₂(CH₃gly)]NO₃ and cis-[Pt(NH_2?CH₃)₂(CH₃gly)]NO₃, have been synthesized and interacted with calf thymus DNA. Improving solubility of these compounds reduce side effects and increase anticancer activity against human breast cell line. Modes of binding have been studied by electronic absorption, fluorescence, and CD measurements. Results show that both Pt(II) complexes can interact to DNA via groove binding.

     

Reactions of Benzoyl Isothiocyanate with Active Methylene Reagents: A Novel Synthesis of Thiophene,Thiazoline and Thieno[2,3-d]Pyrimidine Derivatives

Various derivatives of thiophene, thiazoline and thienopyrimidine have been synthesized via the reaction of active methylene reagents (la-j) with benzoyl isothiocyanate in the presence of potassium hydroxide, followed by the subsequent treatment of the potassium salt intermediates 2a-j with phenacyl bromide or ethyl chloroacetate. The stability of the formed adducts 3 and 12 or their selective cyclization depends on both the nature of the active methylene reagent and the α-halocarbonyl compounds.     

Selective response of dopamine in the presence of ascorbic acid on carbon paste electrode modified with titanium phosphated silica gel

Titanium phosphate grafted on the surface of silica gel (devoted briefly as Si-TiPH) was synthesized and used as bulk modifier to fabricate a renewable three-dimensional chemically modified electrode. The Si-TiPH bulk modified carbon paste electrode was used for the selective determination of dopamine (DA) in the presence of ascorbic acid (AA). The modified electrode offers an excellent and stable response for the determination of DA in the presence of AA. The differential pulse voltammetry peak current was found to be linear with the DA concentration in the range 2 × 10⁻⁷ to 1 × 10⁻⁶ and 2 × 10⁻⁶ to 6 × 10⁻⁵ mol L⁻¹. The detection limit of the proposed method in the presence of 2.0 × 10⁻⁵ M of AA was found to be 4.3 × 10⁻⁸ mol L⁻¹ for DA determination. The proposed method was successfully applied for the determination of DA in injections.