The influence of oxidation number of sulfur on the polymerization and thermo-mechanical properties of dimethacrylate copolymers

Structure and characterization of the sulfur-containing monomers bis[4(2-hydroxy-3-methacryloyloxypropoxy)phenyl]sulfide (S·DM), bis[4(2-hydroxy-3-methacryloyloxypropoxy)phenyl]sulfinyl (SO·DM), bis[4(2-hydroxy-3-methacryloyloxypropoxy)phenyl]sulfonyl (SO₂·DM), and their photopolymerization with N-vinyl-2-pyrrolidone (NVP) are presented. The monomers were obtained in the reaction of derivatives of aromatic diols with 2-(chloromethyl)oxirane in the two-phase liquid/liquid system, including organic and aqueous phases. Next, esterification of the obtained diglycidyl ether was carried out with the use of methacrylic acid. Photopolymerization of the compositions (S·DM, SO·DM, SO₂·DM and NVP) and the initiator (Irgacure 651) was carried out. The influence of oxidation number of sulfur on the properties of the obtained copolymers was studied. The following properties were determined: density, glass transition temperature, Young’s modulus, hardness and tensile strength. Additionally, dynamic-mechanical and thermal properties were investigated. Thermal properties of copolymers under different conditions (in air, in nitrogen and in helium) were tested.     

New Look into the Synthesis of Polyhalogenoarylphosphanes

The present study shows new aspects of the synthesis of polyhalogenoarylphosphanes. The sterically hindered anions Ph(R)P-Y^? (1a–c, Y = O, lone pair; R = Ph, Bu^t) have been used to show the complexity of the reaction between phosphorus nucleophiles and hexahalogenobenzenes or 9-bromofluorene (E3). The Ph(Bu^t)P-O^? (1a) anion reacts with hexachlorobenzene (E1), hexafluorobenzene (E2), or E3 to give Ph(R)P(O)X (4a–c, X = F, Cl, Br) with the release of the corresponding carbanion as a nucleofuge, followed by side reactions. In contrast, the lithium phosphides Ph(R)PLi (1b,c) react with hexahalogenobenzenes to give the corresponding diphosphanes 5a,b as the main product and traces of P-arylated products, i.e., Ph(R)P-C₆X₅ (10a,b, X = Cl, F). Unexpectedly, Ph(Bu^t)PLi (1b) reacts with an excess of 9-bromofluorene to give only halogenophosphane Ph(Bu^t)P-X.     

Detailed study of a two component smectic 4TPB–8OCB system with a nematic gap. Phase diagram and viscosity study

Abstract

The phase diagram of a two component system composed of two smectic compounds: 4-octyloxy-4′-cyanobiphenyl (8OCB) and 4-isothiocyanatophenyl 4-butylbenzoate (4TPB) was investigated. Three Miesowicz viscosity coefficients η₁, η₂, η₃ and the refractive indices at different temperatures as well as the enthalpies of the phase transitions were measured. It was stated, that the properties of the induced nematic phase, for example, the nematic phase existing between two smectic regions, are the same as the ones observed in the case of low viscosity nematic mesogens.     

Major and Trace Elements in Spruce Needles from Urban Areas: Some Aspects of Analysis in Environmental Studies

Main and trace elements in samples of spruce needles from urban areas in Poland and Norway were analysed using the ICP-AES method. Concentrations of Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, P, Sr, Ti, V and Zn were measured in needles from conifer trees growing in different locations. Two different procedures of laboratory sample preparation were compared and discussed. Different washing procedures were examined and compared. For quality control of analytical measurements, Standard Reference Material BCR CRM 101 (spruce needles from Europe) was used. Synergistic and antagonistic relationships between elements in spruce needles were investigated. Applicability of spruce needles in biomonitoring of environmental metal pollution was discussed.     

Biosorption of toxic metals using freely suspended Microcystis aeruginosa biomass

This paper describes the potential application of a freely suspended cyanobacterial biomass of Microcystis aeruginosa as a sorption material for toxic metals, cadmium (Cd) and lead (Pb) from aqueous solutions. In order to identify the most suitable conditions for removal of these elements (concentration range: 1–20 mg L^?1), the laboratory experiments were carried out during different incubation times (1–48 h) and under various temperatures (10–40°C), pH (5–9) and with or without light irradiance. Competitive biosorption of Cd and Pb was also investigated. We found that M. aeruginosa demonstrates high efficiency in removing both of the studied metals from aqueous solutions. Sorption of Pb occurred, however, more rapidly and effectively, and was less disturbed by changes in physico-chemical conditions. Under pH=7, 25°C and light, the removal rates after 3 h and 6 h of incubation, were 90–100% for Pb and 79.5–100% for Cd, respectively. The co-occurrence of the metals decreased the rate of metal biosorption. Pb was sequestered preferentially over Cd. From the results we conclude that freely suspended M. aeruginosa can constitute a promising low-cost, easy-producible biosorbent material for toxic metals in contaminated wastewater.      

Elongation method with intermediate mechanical and electrostatic embedding for geometry optimizations of polymers

The elongation method with intermediate mechanical and electrostatic embedding (ELG-IMEE) is proposed. The electrostatic embedding uses atomic charges generated by a charge sensitivity analysis (CSA) method and parameterized for three different population analyses, namely, the Merz–Singh–Kollman scheme, the charge model 5, and the atomic polar tensor. The obtained CSA models were tested on two model systems. Test calculations show that the electrostatic embedding provides several times of decrease in the difference of energies of testing and reference calculations in comparison with the conventional elongation approach (ELG). The mechanical embedding is implemented in a combination of the conventional elongation method and the ONIOM approach. Moreover, it was demonstrated that the geometry optimization with the ELG-IMEE reduces the errors in the optimized structures by about one order in root-mean-square deviation, when compared to ELG.     

Sturmian Ground States in Classical Lattice–Gas Models

Journal of Statistical Physics - We construct for the first time examples of non-frustrated, two-body, infinite-range, one-dimensional classical lattice–gas models without periodic...     

Impact of subgrid fluid turbulence on inertial particles subject to gravity

Two-phase turbulent flows with the dispersed phase in the form of small, spherical particles are increasingly often computed with the large-eddy simulation (LES) of the carrier fluid phase, coupled to the Lagrangian tracking of particles. To enable further model development for LES with inertial particles subject to gravity, we consider direct numerical simulations of homogeneous isotropic turbulence with a large-scale forcing. Simulation results, both without filtering and in the a priori LES setting, are reported and discussed. A full (i.e. a posteriori) LES is also performed with the spectral eddy viscosity. Effects of gravity on the dispersed phase include changes in the average settling velocity due to preferential sweeping, impact on the radial distribution function and radial relative velocity, as well as direction-dependent modification of the particle velocity variance. The filtering of the fluid velocity, performed in spectral space, is shown to have a non-trivial impact on these quantities.     

Comparison of the impact of the addition of three alkaline earth metal oxides BaO,SrO and ZnO on sintering of glass–ceramic glazes from the SiO2–Al2O2–CaO–MgO–Na2O–K2O system

Journal of Thermal Analysis and Calorimetry - Glazes are the most important elements in the technology of producing the ceramic wares. They not only give aesthetic effects, like color and gloss,...     

Flow of Emulsions Stabilized by Polymers Through Packed Bed

Transport in Porous Media - In this study, we present the results of measurements of pressure drops during the flow of emulsions stabilized by carboxymethylcellulose sodium salt (NaCMC), xanthan...