Rheological model optimization using advanced evolutionary computation for the analysis of the influence of recycled rubber on rubber blend dynamical behaviour

Rheological models of tested rubber blend samples, with different ratios of smut/recycled material, were developed, analyzed and discussed according to experimental data. The experimental measurements show the dynamical behavior of these samples after a short-term axial load. The rheological model of samples was assumed as a viscoelastic Voigt-Maxwell and hyperelastic Mooney-Rivlin model. Real coded genetic algorithms were implemented for optimal model parameters identification in order to minimize the difference between the real sample behavior and dynamical model output. Numerical results obtained for analyzed mixture were compared with the original sample to verify the presented method. In purpose of predicting the dynamical characteristics for desirable rubber blends, an interrelation was formed based on the concentration of recycled material in sample blends and dynamical model parameters dependence.     

Benefits of mesopores in sulfated zirconia catalyst

Activities of two catalysts obtained from hydroxide and alkoxide precursors were correlated to their different structural and textural properties. Activity is mainly determined by the presence of active tetragonal phase, which is more stable at high temperatures in the catalyst of alkoxide origin than in one from hydroxide. An appropriate structure must be accompanied with beneficial pore structure, as is the case of mesopores of the catalyst from alkoxide. In the case of very small pores of the catalyst from hydroxide precursor, activity is negligible due to pores plugged by coke.     

A new method for finding cycles by semilinear control

In the paper two new results that prove typically real and local univalent properties of certain class of rational functions in the unit disc $\mathbb{D}$ are presented. They provide a theoretical justification of a new method for finding periodic solutions of the discrete vector dynamical systems. The main goal of the paper is to propose and investigate the two-delays generalization of the scheme introduced by Ö. Morgül. The analysis shows that the coefficients in the proposed method can be chosen in a way that improves the admissible range of parameters. The method is elementary and easy to implement. Furthermore, numerical experiments with several well known maps show effectiveness of the control scheme.     

Modulation of Magneto-Intersubband Oscillations in a One-Dimensional Lateral Superlattice

JETP Letters - Low-temperature magnetotransport in a quasi-two-dimensional electron system based on a selectively doped GaAs quantum well with two occupied quantum-confinement subbands with...     

On the cusp forms for the congruence subgroups of SL 2(ℝ)

Let N≥3 be an integer. In this paper we show the existence of infinitely many Maass forms for the principal congruence subgroup γ(N) coming from the unitary non-spherical principal series of SL ₂(?) using adelic methods on cuspidal compactly supported Poincaré series.     

Titanium(IV) carboxylate complexes: Synthesis,structural characterization and cytotoxic activity

Four titanium(IV) carboxylate complexes [Ti(η⁵-C₅H₅)₂(O₂CCH₂SMes)₂] (1), [Ti(η⁵-C₅H₄Me)₂(O₂CCH₂SMes)₂] (2), [Ti(η⁵-C₅H₅)(η⁵-C₅H₄SiMe₃)(O₂CCH₂SMes)₂] (3) and [Ti(η⁵-C₅Me₅)(O₂CCH₂SMes)₃] (4; Mes = 2,4,6-Me₃C₆H₂) have been synthesised by the reaction of the corresponding titanium derivatives [Ti(η⁵-C₅H₅)₂Cl₂], [Ti(η⁵-C₅H₄Me)₂Cl₂], [Ti(η⁵-C₅H₅)(η⁵-C₅H₄SiMe₃)Cl₂] and [Ti(η⁵-C₅Me₅)Cl₃] and two (for 1–3) or three (for 4) equivalents of mesitylthioacetic acid. Complexes 1–4 have been characterized by spectroscopic methods and the molecular structure of the complexes 1, 2 and 4 have been determined by X-ray diffraction studies. The cytotoxic activity of 1–4 was tested against tumor cell lines human adenocarcinoma HeLa, human myelogenous leukemia K562, human malignant melanoma Fem-x, and normal immunocompetent cells, that is peripheral blood mononuclear cells PBMC and compared with those of the reference complexes [Ti(η⁵-C₅H₅)₂Cl₂] (R1), [Ti(η⁵-C₅H₄Me)₂Cl₂] (R2), [Ti(η⁵-C₅H₅)(η⁵-C₅H₄SiMe₃)Cl₂] (R3) and cisplatin. In all cases, the cytotoxic activity of the carboxylate derivatives was higher than that of their corresponding dichloride analogues, indicating a positive effect of the carboxylato ligand on the final anticancer activity. Complexes 1–4 are more active against K562 (IC₅₀ values from 72.2 to 87.9 μM) than against HeLa (IC₅₀ values from 107.2 to 142.2 μM) and Fem-x cells (IC₅₀ values from 90.2 to 191.4 μM).     

In and Ex Situ Studies of the Formation of Layered Microspherical Hydrozincite as Precursor for ZnO

Layered ZnO microspheric particles were prepared by the thermal decomposition of layered hydrozincite (LZnHC), which was synthesized from zinc nitrate and urea in a water/PEG400 mixture. The influence of the starting reagents, their concentrations, and the amount of PEG in the water/PEG400 mixture on the particle growth was observed. The chemical aspect of the particle growth was proposed in the frame of the partial charge model (PCM), and the formation of [Zn(OH)₂(OH₂)₄]⁰ and [Zn(OH)(HCO₃)(OH₂)₃]⁰ was predicted for the solid phase. The assumed growth mechanism, which follows the “nonclassical crystallization” concept of a self‐assembling mechanism, was observed in situ by small‐angle X‐ray scattering (SAXS) and predicts the rapid formation of approximately 6 nm sized building units. The size of these nano building units, stable only in the reaction medium, remains nearly constant during the synthesis, as the concentration of the nano building units increases throughout the reaction. The nano building units connect into leaves of LZnHC with a thickness of 20 nm. These leaves of LZnHC are further agglomerated into porous, microsphere‐like particles with sizes up to 4 μm.     

Extraction of lutetium(III) from aqueous solutions by employing a single fibre‐supported liquid membrane

Transport behaviour of Lu(III) across a polypropylene hollow fibre‐supported liquid membrane containing di(2‐ethylhexyl)phosphoric acid (DEHPA) in dihexyl ether as a carrier has been studied. The donor phase was LuCl₃ in the buffer solution consisting of 0.2 M sodium acetate at pH 2.5–5.0. A miniaturised system with a single hollow fibre has been operated in a batch mode. The concentration of Lu(III) was determined by indirect voltammetric method using Zn–EDTA complex. The effect of pH and volume of the donor phase, DEHPA concentration in the organic (liquid membrane) phase, the time of extraction and the content of the acceptor phase on the Lu(III) extraction and stripping behaviour was investigated. The results were discussed in terms of the pertraction and removal efficiency, the memory effect and the mean flux of Lu(III). The optimal conditions for the removal of ¹⁷⁷Lu(III) from labelled ¹⁷⁷Lu‐radiopharmaceuticals were discussed and identified. The removal efficiency of Lu(III) greater than 99% was achieved at pH of the donor phase between 3.5 and 5.0 using DEHPA concentration in the organic phase of 0.47 M and the ratio of the donor to the acceptor phase of 182.     

Selective recruitment of membrane protein complexes onto gold substrates patterned by dip-pen nanolithography

Dip-pen nanolithography (DPN) is employed to develop a generic array platform for the selective recruitment of membrane protein complexes. An atomic force microscope tip inked with HS(CH2)16NH2 is used to generate amino-terminated domains on gold. These domains can be arranged into microscopic and submicroscopic patterns, and the untreated gold substrate is subsequently blocked with HS(CH2)2CONH(CH2CH2O)15CH3, a compound known to resist the unspecific binding of proteins and cells. The patterned gold substrate is exposed to an enriched membrane fraction from mutant Rhodobacter sphaeroides, which contains photosynthetic core complexes consisting of the reaction center and the light-harvesting complex LH1. The selective recruitment to the patterned domains, governed primarily by electrostatic interactions, is confirmed by contact mode atomic force microscopy.