Accurate interpolation of the dependency of modal properties on the rotation speed for the transient response analysis of bladed disks

During fast gas-turbine engine acceleration and deceleration the transient vibration effects in bladed disk vibration become significant and the transient response has to be calculated. In this paper an effective method is developed for efficient calculations of the transient vibration response for mistuned bladed disks under varying rotation speeds. The method uses the large-scale finite element modelling of the bladed disks allowing the accurate description of the dynamic properties of the mistuned bladed disks. The effects of the varying rotation speed on the natural frequencies and mode shapes of a mistuned bladed disk and its effects on the amplitude and the spectral composition of the loading are considered. The dependency of the modal characteristics on the rotation speed are based on the evaluation of these characteristics at reference points followed by the interpolation to obtain values at any rotation speed from the operating range. A new method has been developed for the interpolation of mode shapes while preserving the orthogonality and mass-normalization of the mode shapes. The method of mode shape interpolation is elaborated for tuned and mistuned bladed disks. The accuracy and efficiency of the method is demonstrated on test examples and on analysis of transient forced response of realistic bladed discs

Densities and Viscosities of Aqueous Amino Acid Ionic Liquids [C_<i>n</i>mim][Ala](<i>n</i> = 3, 4, 5)

Amino acid ionic liquids [C_<i>n</i>mim]­[Ala] (<i>n</i> = 3, 4, 5) (1-alkyl-3-methylimidazolium alanine salt) were prepared by the neutralization method. The density and viscosity for aqueous solutions of the ionic liquids (ILs) with various molalities were measured at <i>T</i> = (288.15 to 328.15) K with an interval of 5 K. In terms of the Jones–Dole equation, the viscosity <i>B</i>-coefficients with large positive values and d<i>B</i>/d<i>T</i> < 0 were obtained, and these facts implied that the ionic liquids are water-structure-making. According to Feakins, the contribution of the solute per mole to the free energy of activation for viscous flow of the solution, Δμ₂^⧧0, or called as the standard molar activation free energy, was obtained at different temperatures. Under the constant molality of solution, Δ<i>H</i>₂^⧧0 (the activation enthalpy of the activation for viscous flow of aqueous [C_<i>n</i>mim]­[Ala] (<i>n</i> = 3, 4, 5)) is a temperature-independent constant. This implies that the activation process of the solute for viscous flow of aqueous [C_<i>n</i>mim]­[Ala] (<i>n</i> = 3, 4, 5) is an isoCoulombic reaction. A semiempirical method to estimate the viscosity of aqueous [C_<i>n</i>mim]­[Ala] (<i>n</i> = 3, 4, 5) was put forward based on Eyring’s theory, and the estimated viscosity values of the aqueous ILs are in good agreement with the corresponding experimental ones

Theoretical Study on Polynuclear Superalkali Cations with Various Functional Groups as the Central Core

A new series of polynuclear superalkali cations YLi₃⁺ (Y = CO₃, SO₃, SO₄, O₄, and O₅) has been created when the central group is surrounded by alkali atoms. The structural characteristics and stabilities of these systems are provided on the basis of ab initio methods. In the lowest-energy structure of the CO₃Li₃⁺, SO₃Li₃⁺, and SO₄Li₃⁺ cations, the central Y (Y = CO₃, SO₃, and SO₄) group features a slight distortion. The global minima of O₄Li₃⁺ and O₅Li₃⁺ are of the forms O₂^–(Li⁺)₃O₂^– and O₂^–(Li⁺)₃O₃^–, respectively, both of which contain two monovalent ion units. The structural integrity of the central Y group and the arrangement of the lithium ligands are two influencing factors on the vertical electron affinities (EA_vert) for the YLi₃⁺ species. The YLi₃⁺ cation, with its lithium ligands being distributed evenly or far from each other, tends to exhibit a low EA_vert value, whereas a greater extent of cleavage of the central Y group leads to a higher EA_vert value and even makes some species lose their superalkali nature

Efficient Flexible Counter Electrode Based on Modified Graphite Paper and in Situ Grown Copper Sulfide for Quantum Dot Sensitized Solar Cells

Flexible counter electrode (CE) plays an important role in portable quantum dot sensitized solar cells (QDSCs). However, the present power conversion efficiency (PCE) of bendable QDSC is rather limited partly due to the unsatisfactory conductivity, flexibility, catalytic activity, and fabrication technique of CE. In this work, flexible CEs composed of Cu_<i>x</i>S and graphite paper (GP) are built and fabricated through a facile successive ionic layer adsorption reaction (SILAR) method. Through designing and optimizing of the surface property of GP, coverage, and thickness of catalyst, excellently performed CEs are achieved with the maximal PCE of 8.70% under one full sun illumination for Zn–Cu–In–Se QDSCs. Further, fully flexible QDSCs assembled with the as-prepared CEs and plastic photoanodes show a high PCE of 2.45% under the same illumination

Surface Properties of Aqueous Solutions of Amino Acid Ionic Liquids: [C₃mim][Gly] and [C₄mim][Gly]

Glycine ionic liquids [C₃mim]­[Gly] (1-propyl-3-methylimidazolium glycine) and [C₄mim]­[Gly] (1-butyl-3-methylimidazolium glycine) have been prepared by the neutralization method and characterized by ¹H NMR spectroscopy and DSC trace. The values of density and surface tension of aqueous [C₃mim]­[Gly] and [C₄mim]­[Gly] with various molality were determined in the temperature range of (288.15 to 328.15 ± 0.05) K, and the experimental values of parachor for these solutions were calculated. Using the empirical equation of parachor, the surface tension of these aqueous solutions was estimated, and the estimated values are in good agreement with experimental values within error

Table 1

<p>(*: KANR was used as a positive control spike).</p><p>doi:10.1371/journal.pone.0082030.t001</p><p>Human Reference Plex Gene Information.</p

Physico-chemical Properties of 1‑Alkyl-3-methylimidazolium Propionate Ionic Liquids {[C_<i>n</i>mim][Pro](<i>n</i> = 3, 4, 5, 6)} from 288.15 K to 328.15 K

Four propionic acid ionic liquids (PrAILs) [C_<i>n</i>mim]­[Pro] (<i>n</i> = 3, 4, 5, 6) (1-alkyl-3-methylimidazolium propionate) were prepared by the neutralization method and characterized by ¹H NMR spectroscopy and differential scanning calorimetry. The values of their density, surface tension, and refractive index were measured in the temperature range of 288.15–328.15 K. Since the PrAILs can strongly form hydrogen bonds with water, the small amount of water is difficult to remove from the PrAILs by conventional methods. To eliminate the effect of the water impurity, the standard addition method (SAM) was applied to these measurements. The dependence of volumetric properties, surface properties, and molar refraction on temperature were discussed. In terms of Kabo’s method the molar enthalpies of vaporization, Δ<i>H</i>^V, for the PrAILs were estimated. As a new idea, it was put forward that Δ<i>H</i>^V can be assumed to consist of two parts: one is the contribution from induced dipole, Δ<i>H</i>^V_<i>n</i>, and the other is the contribution from the permanent dipole of ion pair in ILs, Δ<i>H</i>^V_μ. The values of Δ<i>H</i>^V_<i>n</i> can be estimated in terms of refractive index data so that the values of Δ<i>H</i>^V_μ can be obtained and Δ<i>H</i>^V_μ may be seen as the measure of polarity for ILs

Determination of the Enthalpy of Vaporization and Prediction of Surface Tension for Ionic Liquid 1‑Alkyl-3-methylimidazolium Propionate [C_<i>n</i>mim][Pro](<i>n</i> = 4, 5, 6)

With the use of isothermogravimetrical analysis, the enthalpies of vaporization, Δ^g_l<i>H</i>^o_m(<i>T</i>_av), at the average temperature, <i>T</i>_av = 445.65 K, for the ionic liquids (ILs) 1-alkyl-3-methylimidazolium propionate [C_<i>n</i>mim]­[Pro]­(<i>n</i> = 4, 5, 6) were determined. Using Verevkin’s method, the difference of heat capacities between the vapor phase and the liquid phase, Δ^g_l<i>C</i>_p^o_m, for [C_<i>n</i>mim]­[Pro]­(<i>n</i> = 2, 3, 4, 5, 6), were calculated based on the statistical thermodynamics. Therefore, with the use of Δ^g_l<i>C</i>_p^o_m, the values of Δ^g_l<i>H</i>^o_m(<i>T</i>_av) were transformed into Δ^g_l<i>H</i>^o_m(298), 126.8, 130.3, and 136.5 for [C_<i>n</i>mim]­[Pro]­(<i>n</i> = 4, 5, 6), respectively. In terms of the new scale of polarity for ILs, the order of the polarity of [C_<i>n</i>mim]­[Pro]­(<i>n</i> = 2, 3, 4, 5, 6) was predicted, that is, the polarity decreases with increasing methylene. A new model of the relationship between the surface tension and the enthalpy of vaporization for aprotic ILs was put forward and used to predict the surface tension for [C_<i>n</i>mim]­[Pro]­(<i>n</i> = 2, 3, 4, 5, 6) and others. The predicted surface tension for the ILs is in good agreement with the experimental one

Superficial Chiral Etching on Achiral Metal–Organic Framework for Enantioselective Sorption

Chiral recognition and separation is of general research interests in natural product separation and the pharmacy industry. In this work, we develop a novel strategy to modify achiral porous metal–organic framework (MOF) surfaces via a <i>superficial chiral etching process</i> (SCEP), in which reacting a presynthesized achiral MOF with a chiral ligand produces an achiral@chiral MOF core–shell hybrid composition. SCEP creates chiral species on an achiral porous MOF surface but does not change the porosity and pore structure, enabling core–shell composition enantioselective sorption. Reacting (+)-camphoric acid, (+)-Cam, and 1,4-diazabicyclo[2.2.2]­octane (Dabco) with [Cu₃(Btc)₂] microcrystals leads to a chiral MOF of [Cu₂((+)-Cam)₂Dabco] crystallites attached on the surface of [Cu₃(Btc)₂] (Btc = 1,3,5-benzenetricarboxylate). The resulting [Cu₃(Btc)₂]@[Cu₂((+)-Cam)₂Dabco] core–shell composition displays preferred sorption kinetics toward (<i>S</i>)-limonene against (<i>R</i>)-limonene, with a similar discrimination effect with pure chiral [Cu₂((+)-Cam)₂Dabco]. Superficial chiral etching of the porous achiral MOF represents an economic and efficient strategy for enantioselective separation

Additional file 1 of Relationship between quantitative epicardial adipose tissue based on coronary computed tomography angiography and coronary slow flow

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