Multifunctional magnetic mesoporous nanocomposites towards multiple applications in dye and oil adsorption

Journal of Sol-Gel Science and Technology - Multifunctional magnetic mesoporous nanocomposites are promising materials to remove the various pollutants from water due to the remarkable properties...     

The Transport Properties of the Cell Membrane Ion Channels in Electric Fields: Bethe Lattice Treatment

The interactive two-state model of cell membrane ion channels in an electric field is formulated on the Bethe lattice by means of the exact recursion relations. The probability of channel opening or maximum fractions of open potassium and sodium channels are obtained by solving a non-linear algebraic equation. Using known parameters for the conventional mean-field theory the model gives a good agreement with the experiment both at low and high trans-membrane potential values. For intermediate voltages, the numerical results imply that collective effects are introduced by trans-membrane voltage.     

Eigenvalues of Two Parameter Polynomial Operator Pencils of Waveguide Type

The spectral structure of two parameter unbounded operator pencils of waveguide type is studied. Theorems on discreteness of the spectrum for a fixed parameter are proved. Variational principles for real eigenvalues in some parts of the root zones are established. In the case of n = 1 (quadratic pencils) domains containing the spectrum are described (see Fig. 1–3). Conditions in the definition of the pencils of waveguide type arise naturally from physical problems and each of them has a physical meaning. In particular a connection between the energetic stability condition and a perturbation problem for the coefficients is given.     

The chemical synthesis of conductive polyaniline doped with dicarboxylic acids

The chemical polymerization of aniline was carried out in media containing different linear dicarboxylic acids with the use of oxidants such as K₂Cr₂O₇, KMnO₄, K₂S₂O₈, KIO₃ and FeCl₃. The highest yield and the conductivity were observed with K₂Cr₂O₇. The yield and the conductivity of the polyaniline (PAn) synthesized were observed to decrease in the order of oxalic acid > malonic acid > succinic acid > glutaric acid > adipic acid > phthalic acid. The solubility tests carried out in solvents such as DMF, DMSO and NMP showed that the larger the dopant molecule, the higher is the solubility of polyaniline. The PAn synthesized was characterized by measurements of conductivity, intrinsic viscosity, density and FTIR, UV-VIS and TGA techniques.     

Ureasulfonamide Polymeric Sorbent for Selective Mercury Extraction

Summary. A new polymeric resin with sulfonamide pendant functions has been prepared for the selective extraction of mercuric ions. This polystyrene sulfonamide urea resin with a 3.5 mmol/g total nitrogen content is able to selectively sorb mercury from aqueous solutions. The mercury sorption capacity of the resin is around 1.60 mmol/g under non-buffered conditions. The experiments performed under identical conditions with some metal ions reveal that Cd(II), Pb(II), Zn(II), and Fe(III) ions are also extractable in low quantity (0.05–0.1 mmol/g). The sorbed mercury can be eluted by repeated treatment with hot acetic acid without hydrolysis of the amide groups.     

Phenolic compounds from the aerial parts of Clematis viticella L. and their in vitro anti-inflammatory activities*

Phytochemical investigations on the EtOH extract of Clematis viticella led to the isolation of six flavonoid glycosides, isoorientin (1), isoorientin 3′-O-methyl ether (2), quercetin 7-O-α-L-rhamnopyranoside (3), quercetin 3,7-di-O-α-L-rhamnopyranoside (4), manghaslin (5) and chrysoeriol 7-O-β-D-glucopyranoside (6), one phenylethanol derivative, hydroxytyrosol (7), along with three phenolic acids, caffeic acid (8), (E)-p-coumaric acid (9) and p-hydroxybenzoic acid (10). The structures of the isolates were elucidated on the basis of NMR and HR-MS data. All compounds were isolated from C. viticella for the first time. Compounds 7 and 8 showed significant anti-inflammatory activity at 100 μM by reducing the release of NO in LPS-stimulated macrophages comparable to positive control indomethacin. Compounds 3 and 7 exhibited anti-inflammatory activity through lowering the levels of TNF-α while 1, 3 and 5 decreased the levels of neopterin better than the positive controls.     

Optimizing control of simulated moving beds--linear isotherm

A new optimization based adaptive control strategy for simulated moving beds (SMBs) is proposed. A linearized reduced order model, which accounts for the periodic nature of the SMB process, is used for online optimization and control. The manipulated variables are the four inlet flow rates, the outputs are the raffinate and extract concentrations. Concentration measurements at the raffinate and extract outlets are used as the feedback information. The state estimate from the periodic Kalman filter is used for the prediction of the outlet concentrations over a chosen horizon. Predicted outlet concentrations are the basis for the calculation of the optimal input adjustments, which maximize the productivity and minimize the desorbent consumption subject to constraints on product purities. The realization of this concept is discussed and the implementation on a virtual eight column SMB platform is assessed, in the case of binary linear systems. For a whole series of typical plant disturbances it is shown that the proposed approach is effective in minimizing off-spec products and in achieving optimal SMB operation, also in the case where there are significant model uncertainties.     

Inter-element interferences in the determination of arsenic and antimony by hydride generation atomic absorption spectrometry with a quartz tube atomizer

The interferences between arsenic and antimony on each other during the hydride generation atomic absorption spectrometry (HGAAS) determination of arsenic and antimony using a quartz tube atomizer (QTA) were examined. In order to eliminate or reduce such interferences by selective heat decomposition of arsine and stibine, a Pyrex adsorption U-tube trap containing glass wool was placed between the drying tube and the quartz tube atomizer. Although at 250 °C stibine decomposes and is held almost completely by the trap, arsine is also decomposed to an extent of 24% and, therefore, thermal decomposition is not useful to eliminate antimony interference on arsenic determination. The effect of coating the glass wool in the U-tube with antimony on the arsenic suppression of the antimony signal was studied. The results showed that the antimony coating in the U-tube could not hold arsenic effectively and its interference on the antimony signal could not be eliminated by this means. In the second part of the study, oxygen was supplied to the quartz tube atomizer during atomization in order to study the effect of supplying oxygen on the antimony signal and on the interference of arsenic in the antimony determination. Sensitivity was increased in the presence of oxygen and interferences of arsenic on antimony determination was decreased by about 10% when oxygen was supplied. It was also observed that the extent of interferences depended mainly on the interferent concentration rather than the analyte concentration.     

Recognition-induced transformation of microspheres into vesicles: morphology and size control

Polystyrene functionalized with diamidopyridine (DAP) recognition units self-assembles in nonpolar media to form thermally reversible micrometer-scale spherical aggregates. The size and the thermal stability of these microspheres can be controlled by the molecular weight of the polymer. The addition of thymine-functionalized polymer to these self-assembled microspheres converted them into vesicular aggregates with a controlled size. The morphology change was reversible: the addition of DAP-functionalized polymer converted the vesicles back to microspheres.