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A nanocomposite of magnetic hydroxyapatite was synthesized and tested as an adsorbent for the removal of copper (Cu (II)) and nickel (Ni(II)) from aqueous solution. The adsorbent was investigated using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy equipped with an Energy Dispersive Spectrometer (SEM/EDS), X-ray powder diffraction (XRD) and the Brunauer–Elmet–Teller nitrogen adsorption technique (BET-N 2 adsorption). Batch experiments were carried out to determine and compare the adsorption parameters of Fe 3 O 4 and its composite with hydroxyapatite. It was found that the adsorbent is nanostructured and has a specific surface area of 101.2 m 2  g −1 . The Langmuir adsorption isotherm was found to be an appropriate model to describe the adsorption processes, showing the adsorption capacities of Cu(II) and Ni(II) of 48.78 mg g −1 and 29.07 mg g −1 , respectively. In addition to the high adsorption capacity, the fully-adsorbed material could be easily separated from aqueous media using an external magnetic field. These results suggested that the utilization of new hydroxyapatite – Fe 3 O 4 nanocomposite for the removal of Cu(II) and Ni(II) is a promising method in water technology. [ABSTRACT FROM AUTHOR]

One of the current problems concerning the re-use of aluminium alloys is the recycling of aluminium alloys with increased content of iron. One of the recent trends is the processing by powder metallurgy, producing completely new grades of aluminium alloys. The aim of the present work was to test the properties of Al–Si–Fe alloy, which can be manufactured from the high-irony scrap, as a possible material for elevated temperature applications. Since chromium and nickel accompany the iron in the scrap when stainless steels are admixed, the effect of chromium and nickel on thermal stability and mechanical properties at room and elevated temperature was also studied. Al–Si–Fe–X alloys were rapidly solidified by using melt spinning technique. The rapidly solidified ribbons were pulverized by planetary ball mill and the obtained powders were used for compaction by means of Spark Plasma Sintering. It was found that nickel improves the thermal stability as well as the mechanical properties at the elevated temperature. On the other hand, the effect of chromium on the mechanical properties at elevated temperature was almost detrimental. [ABSTRACT FROM AUTHOR]

This work deals with a problem of paraxial analysis of optical systems for transformation of Gaussian beams. General equations describing the paraxial parameters of a two-element zoom system for transformation of a Gaussian beam are derived. It is shown that such a zoom lens has different kinematics with respect to classical zoom system designed for homocentric beams, which depends on the parameters of the transformed Gaussian beam. [ABSTRACT FROM AUTHOR]

Abstract: This work is devoted to the preparation of ultrafine material based on Al–Cu–Fe quasicrystalline phase by powder metallurgy using mechanical alloying and Spark Plasma Sintering. The dependence of microstructure and phase composition of powders on the conditions of mechanical alloying was described. It was found that the Al60Cu30Fe10 quasicrystalline phase forms directly already after 2 h of milling under optimized conditions. The stability of this quasicrystalline phase was studied at various temperatures of Spark Plasma Sintering compaction process. [Copyright &y& Elsevier]

Abstract: Our work is focused on the problem of theoretical evaluation of the surface shape of a variable focus membrane lens. In order to be able to determine the imaging properties of such a lens one has to know the shape of the membrane for a given pressure of the liquid inside the lens chamber with high accuracy. In our work a generalized nonlinear differential equation describing this problem is derived and the solution of this equation using expansion into series and transformation of the problem into constraint optimization problem is proposed. The proposed method enables us to calculate the shape of a membrane lens surface with satisfactory accuracy for further calculations such as e.g. calculation of aberrations of such a lens, imaging properties etc. [Copyright &y& Elsevier]

Abstract: This work deals with a problem of an effective and robust evaluation of Cartesian partial derivatives of Zernike polynomials. Calculations based on explicit relations suffer from high computational costs and are numerically instable for higher orders. Thus, fast and numerically stable methods for calculation of derivatives of Zernike polynomials are needed. Such methods employing recursive techniques based on the relation of Zernike radial polynomials to Jacobi polynomials are proposed. The performance of proposed algorithms is compared to the standard calculation using explicit relations. [Copyright &y& Elsevier]

This work aims to optimize the parameters of the SHS process for the preparation of NiTi shape memory alloy to obtain a high-purity, low-porosity material. For this purpose, high heating rate (over 300 °C min−1), temperature of 1100 °C and process duration of 20 min were determined as the optimal parameters. To prevent nickel depletion of the product and to minimize the porosity, the use of coarse titanium particles (200–600 μm) with fresh surface can be recommended. SHS products were composed of NiTi with the admixture of Ti2Ni phase. The formation of this phase cannot be fully avoided in SHS preparation route. [ABSTRACT FROM AUTHOR]

Abstract: This work aims to describe the effect of alloying by transition metals (Co, Cr, Cu, Fe, Ni, Mo) on the structure and properties of TiAl15Si15 alloy prepared by SHS technique. Results show that alloying elements do not form their own phases in detectable amounts, being dissolved in titanium silicide or aluminide. Co, Cu and Ni were determined mainly in aluminide, while iron was found predominantly in the silicide phase. Chromium and molybdenum dissolve in both aluminide and silicide in almost comparable amounts. All applied alloying elements increase the wear resistance and the oxidation resistance at 1000 °C, but reduce the room-temperature mechanical properties. Molybdenum-alloyed material exhibits the best oxidation resistance, followed by chromium-containing alloy. These alloys are also characterized by exceptional thermal stability. [Copyright &y& Elsevier]