Synthesis of nanosized β-BiTaO4 by the polymeric precursor method

β-BiTaO₄ powder was synthesized by the citrate method, using bismuth citrate and TaCl₅ as precursors. The citrate gel was characterized by thermal analyses (TG and DTA), in order to determine the best polymerization temperature. The polymeric precursor is essentially amorphous and after calcination at 400 °C a mixture of tantalates, that are isomorphic to Bi₃NbO₇ and Bi₅Nb₃O₁₅, starts to crystallize. At 600 °C, in addition to those phases, one could observe some peaks related to β-BiTaO₄. Finally, at 800 °C β-BiTaO₄ can be observed as a pure phase, with particle size estimated as 47 nm. The precursor polymeric method allowed obtaining β-BiTaO₄ pure phase at temperatures significantly lower than those found for solid state reaction method.     

Application of the fundamental solutions by Ganowicz in a static analysis of Reissner’s plates by the boundary element method

In this paper the direct non-singular formulation of the boundary element method using the fundamental solutions given by Ganowicz (1966) [6] and its application to a static analysis of plates with intermediate thickness is presented. A more exact calculation of almost singular integrals is possible, thanks to the applied modification of the Gauss integration procedure with the inversed distribution of integration points. The non-singular method is based on an offset of collocation points from a plate boundary. The accuracy of results depends on this offset, so the analysis of a relation between the distance of the collocation point from the plate and the conditioning of the matrix of integral equations is carried out. The optimal distance equal to 0.01 of the boundary element length was determined. The presented approach allows to carry out the static analysis of plates with arbitrary shapes including plates with holes. Solution of thin plates is also possible.     

Eigenvalue analysis for acoustic problem in 3D by boundary element method with the block Sakurai–Sugiura method

This paper presents accurate numerical solutions for nonlinear eigenvalue analysis of three-dimensional acoustic cavities by boundary element method (BEM). To solve the nonlinear eigenvalue problem (NEP) formulated by BEM, we employ a contour integral method, called block Sakurai–Sugiura (SS) method, by which the NEP is converted to a standard linear eigenvalue problem and the dimension of eigenspace is reduced. The block version adopted in present work can also extract eigenvalues whose multiplicity is larger than one, but for the complex connected region which includes a internal closed boundary, the methodology yields fictitious eigenvalues. The application of the technique is demonstrated through the eigenvalue calculation of sphere with unique homogenous boundary conditions, cube with mixed boundary conditions and a complex connected region formed by cubic boundary and spherical boundary, however, the fictitious eigenvalues can be identified by Burton–Miller's method. These numerical results are supported by appropriate convergence study and comparisons with close form.     

High-throughput analysis of ligand-induced internalization of β2-adrenoceptors using the coiled-coil tag-probe method

Receptor internalization is a useful indicator of the activity of ligands. The N-terminus of the β(2)-adrenergic receptor expressed on the cell surface was labeled with fluorophores using a novel coiled-coil labeling system. Endocytosis of the receptors was automatically detected using a fluorescence image analyzer by evaluating (1) translocation of the receptor from cell-surface to intracellular regions and (2) acidification in endosomes. Both parameters increased upon agonist stimulation in a dose-dependent manner. The extent of endocytosis was significantly dependent on the agonist used, indicating the presence of a biased signaling for endocytosis. The receptor antagonists can also be screened by competitive inhibition of agonist-induced endocytosis. The image analysis approach has proven to be useful for high-throughput characterization and screening of GPCR ligands.     

Bandgap modifications by lattice deformations in β-FeSi2 epitaxial films

The modifications of direct transition energies by lattice deformations were investigated in β-FeSi₂ epitaxial films, polycrystal films and single crystal, systematically. The lattice deformations depending on thermal annealing temperature (T_a) were observed in β-FeSi₂ epitaxial films. In photoreflectance (PR) measurements, the direct transition energies of the epitaxial films shifted to lower energies as the T_a increased. The polycrystal films did not show the lattice deformation and the shift of direct transition energies. These results show that the direct bandgap is modified by the lattice deformation originating from the lattice mismatch at the hetero-interface of β-FeSi₂/Si.     

Stability analysis of the Fourier–Bessel method for the Cauchy problem of the Helmholtz equation

This paper is concerned with the Cauchy problem connected with the Helmholtz equation in a smooth-bounded domain. The Fourier–Bessel method with Tikhonov regularization is applied to achieve a regularized solution to the problem with noisy data. The convergence and stability are obtained with a suitable choice of the regularization parameter. Numerical experiments are also presented to show the effectiveness of the proposed method.     

A systematic AMF–FEM coupled method for the thermo-elasto-plastic contact analysis of the plasma sprayed HA-coated biocomposite

Hydroxyapatite (HA) coated Ti-6Al-4V alloy biocomposite has been accepted as one of the most promising implant materials for orthopaedic and dental applications because of its favorable biocompatibility and mechanical properties. After the plasma sprayed HA composite coating on titanium alloy substrate biocomposite was prepared, a novel meshless numerical analysis method of the coupled adaptive meshfree method and finite element method (AMF–FEM) is developed for the simulation of the thermo-elasto-plastic contact problems of the biocomposites in this paper. The adaptive meshfree method based on strain energy gradient is used in the concerned contact domain, and FEM is used in the non-contact domain to overcome the difficulties of the meshfree method and improve the calculation efficiency. The thermo-elasto-plastic contact model using the incremental-initial stiffness method, error estimation and the local adaptive refinement strategy for the AMF–FEM method are combined. The AMF–FEM thermo-elasto-plastic model takes into account the temperature variation, micro plastic flow, the thermo-elasto-plastic coupling behavior and the strain-hardening property of the materials. The examples of the elastic/thermal-elastic contact of real HA-coated rough surfaces using the AMF–FEM is studied for two biomaterial models, respectively. The results all show that the AMF–FEM solutions are accurate, efficient, and can be widely applied to different thermo-elasto-plastic contact multi-layer biomaterial models considering different geometric parameter, material parameter, thermal and friction properties.     

A method of combining rigid body displacements for the determination of rigid body rotations of structural members in the slope‐deflection method

Abstract

In this paper we investigate the stresses and displacements around an advancing face of a tunnel in an elastic half‐space as well as the induced three‐dimensional ground surface subsidence. An indirect boundary integral formulation for the analysis of tunnels in an elastic half‐space is derived and the half‐space fundamental solution (Mindlin's solution) is adopted to satisfy the traction‐free condition on the ground surface. For the evaluation of the non‐singular integral in the numerical implementation, a simple and efficient algorithm to automatically search for integration orders is developed by basing on the upper bound of error in Gaussian quadrature. Numerical results for some tunnel problems are studied to demonstrate the accuracy and versatility of the proposed method. In addition, the stresses, displacements, and the induced ground surface subsidence for an advancing circular tunnel in an elastic half‐space are calculated and presented in detail.     

A supersaturation model for the degradation of sodium β/β″-aluminas

A mechanism is proposed for the sodium degradation of / alumina electrolytes. It is based on the Na⁺ supersaturation of feeder grains peripheral to flaws in the liquid-sodium/ electrolyte interface. This supersaturation is brought about by the focusing of the current by the flaw and leads to local oxidation of oxygen ions in the aluminate structure. This process leads to the formation of colour-centres and sodium atoms in the grains. The latter coalesce to form sodium colloids, microcracking the microstructures. These microcracks join the originating flaw and promote its extension. A model is presented which demonstrates the feasibility of the proposed degradation mechanism and it is discussed in light of other associated physical phenomena.     

How well developed are altmetrics? A cross-disciplinary analysis of the presence of ‘alternative metrics’ in scientific publications

In this paper an analysis of the presence and possibilities of altmetrics for bibliometric and performance analysis is carried out. Using the web based tool Impact Story, we collected metrics for 20,000 random publications from the Web of Science. We studied both the presence and distribution of altmetrics in the set of publications, across fields, document types and over publication years, as well as the extent to which altmetrics correlate with citation indicators. The main result of the study is that the altmetrics source that provides the most metrics is Mendeley, with metrics on readerships for 62.6 % of all the publications studied, other sources only provide marginal information. In terms of relation with citations, a moderate spearman correlation (r = 0.49) has been found between Mendeley readership counts and citation indicators. Other possibilities and limitations of these indicators are discussed and future research lines are outlined.     

Development of solid dispersions of β-lapachone in PEG and PVP by solvent evaporation method

β-lapachone (βlap) has shown potential use in various medical applications. However, its poor solubility has limited its systemic administration and clinical applications. The aim of this work is to develop solid dispersions of βlap using poly (ethylene glycol) (PEG 6000) and polyvinylpyrrolidone (PVP K30) as hydrophilic polymers and evaluate the dissolution rate in aqueous medium. Solid dispersions were prepared by solvent evaporation method using different weight ratios of βlap and hydrophilic polymer (1:1, 1:2, and 1:3). Characterization performed by differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy showed that βlap was molecularly dispersed within the polymer matrix. The in vitro dissolution tests showed an enhancement in the dissolution profile of βlap as solid dispersions prepared in both PVP and PEG, although the former showed better results. The drug:polymer ratio influenced βlap dissolution rate, as higher amounts of hydrophilic polymer led to enhanced drug dissolution. Thus, this study demonstrated that solid dispersions of βlap in PVP offers an effective way to overcome the poor dissolution of βlap.     

A Monte Carlo simulation for the study of the influence of the thickness of the source in 3H β-ray spectroscopy

A Monte Carlo simulation for the study of the influence of the thickness of the radioactive source in β-ray spectroscopy is presented in this paper. We make use of the Bethe-Bloch formula for ionization loss and Rutherford scattering cross section to trace the tracks of the β particles from a randomly sampled point source of given energy, which has been implanted in an aluminum coating with copper backing. We have studied seven groups of β rays with momenta from 119.14262 to 139.12328 keV/c. There are the peak shift, the broadening of the line width and the low energy tail. Their momentum dependences have been found. The program can be applied to similar cases with minor modification.     

A Burton–Miller formulation of the boundary element method for baffle problems in acoustics and the BEM/FEM coupling

Baffle problems, i.e. radiation problems from objects mounted behind a hole of an infinite hard reflecting wall, can be simulated as a multi domain problem consisting of a finite interior domain around the object, and two infinite half spaces in front and behind the baffle plane. A formulation of such problems is presented in the context of the Burton–Miller boundary element method. Additionally, the coupling of the acoustic boundary element method and the structural finite element method in the context of the Burton–Miller-formulation of the baffle problem is discussed.     

Allowance for the self-absorption of γ rays in the activation analysis of bulk samples

The self-absorption coefficient is determined numerically from a family of empirical -ray absorption curves for cylindrical samples of various thicknesses, atomic weights, and densities.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 46, No. 6, pp. 998–1002, June, 1984.     

Theoretical error analysis of the sampling moiré method and phase compensation methodology for single-shot phase analysis

Recently, a rapid and accurate single-shot phase measurement technique called the sampling moiré method has been developed for small-displacement distribution measurements. In this study, the theoretical phase error of the sampling moiré method caused by linear intensity interpolation in the case of a mismatch between the sampling pitch and the original grating pitch is analyzed. The periodic phase error is proportional to the square of the spatial angular frequency of the moiré fringe. Moreover, an effective phase compensation methodology is developed to reduce the periodic phase error. Single-shot phase analysis can perform accurately even when the sampling pitch is not matched to the original grating pitch exactly. The primary simulation results demonstrate the effectiveness of the proposed phase compensation methodology.     

A study of the heat-removal process at the semiconductor–ceramics interface in solar cells by the laser thermal-wave method

The influence of the solder layer between a semiconductor solar cell and heat-removing ceramics on the nonstationary heat-transfer processes has been investigated by the laser thermal-wave method. A theoretical model taking into account the presence of additional thermal resistance and thermal capacitance at the soldered junction is proposed. Different soldering modes are considered. It is shown that the laser thermal- wave methods within the developed model allow one to correctly estimate the thermophysical properties of multilayer structures.     

Application of pyrolysis–gas chromatography/mass spectrometry for the identification of polymeric materials in failure analysis in the automotive industry

The application of analytical pyrolysis–gas chromatography mass spectrometry (Py–GC/MS) in the failure analysis of two hydraulic cylinders and their rubber membranes from the automotive industry were presented.