Development and characterization of a titanosilicate ETS-10-coated optical fiber reactor towards the photodegradation of methylene blue

An optical fiber reactor (OFR) system containing uniformly distributed quartz fibers coated with titanosilicate ETS-10 crystals was investigated. Optimum ETS-10 film thickness (～1.5 μm) and coating length (15 cm) were determined from the light propagation analysis in a single ETS-10-coated fiber. The nearly constant value of the attenuation coefficient (α ≈ 0.10 cm^?1) for films with different thickness indicated uniform fiber surface coverage with these films. The extinction coefficient, ?, decreased from ～1.6 to ～1.0 μm^?1 with ETS-10 film thickness increasing from ～0.5 to ～1.5 μm, which suggested less contact per unit film thickness between light and ETS-10 crystals inside thicker films, likely due to their lower crystal packing density. Photodegradation of methylene blue (MB) conducted in the OFR showed higher photocatalytic activity for thicker ETS-10 films. Although higher MB photodegradation rates were obtained at higher light intensity, the apparent quantum efficiency, Φ, decreased with increasing light intensity. This is consistent with the charge separation mechanism for MB photodegradation in the UV light range investigated. All ETS-10 samples investigated showed ～4–5 times higher Φ values in the OFR than in the slurry reactor, likely due to the unique light/photocatalyst/reactant contact and high fiber packing density in the OFR.     

Aggregation and adsorption of sodium dioctylsulfosuccinate in aqueous ammonium chloride solution: role of mixed counterions

The critical micelle concentration (cmc) of sodium dioctylsulfosuccinate (AOT) was determined at 25 °C from surface tension and fluorescence methods in aqueous NH(4)Cl solution for assessing the influence of mixed counterions on the special counterion binding behavior (SCB) of AOT. The SCB of AOT refers to a sudden twofold increase in the value of the counterion binding constant (β) in aqueous medium when the concentration (c(*)) of the added 1:1 sodium salt is about 0.015 mol kg(-1), and it has been tested so far for sodium ion only. In the presence of sodium and ammonium mixed counterions also the SCB of AOT exist, but with lower c(*) (0.009 mol kg(-1) NH(4)Cl). Synergism in the cmc occurs due to mixed counterions. In the case of inorganic counterions, unlike the case with organic counterions, the cmc is dependent on the total counterion concentration in solution and negligibly on the specific type of counterion. Na(+) and NH(4)(+) bind almost equally to the micelle in the region of low β (below c(*)), but in the region of high β (above c(*)) NH(4)(+) binds predominantly. It has been shown that the theoretical expression for the surface excess of ionic surfactant+electrolyte system containing a single counterion can also be used to evaluate the surface excess in the presence of mixed counterions if the two counterions are considered to undergo Henry-type adsorption at the air-solution interface.     

Solvent Effects on the Kinetics of Amide Bond Cleavage in p-Chloro and p-Bromo Oxazolinones in Acetonitrile–Water Mixtures

The kinetics of amide bond cleavage in p-chloro and p-bromo oxazolinone have been studied using triethylamine as a base catalyst under pseudo-first order conditions, in the temperature range (303.15?C333.15?K). The reaction rate was measured spectrophotometrically over a range of acetonitrile?Cwater mixed solvent (30?C70?%, v/v) compositions. The reaction rate was found to be faster for p-Cl than for p-Br oxazolinone. The thermodynamic parameters of activation were calculated: ?G* increased gradually as the mole fraction of the cosolvent increased due to quasi-mirror image compensation of ?H* and ?S* (entropy?Centhalpy compensation). The isokinetic temperature indicates that the reaction is enthalpy controlled. The reactivity was analyzed in the light of various simple and multiple regression equations using the Kamlet?CTaft solvatochromic parameters.     

Synthesis and Characterization via Molecular Quantum Parameters of 2H‐Thiazolo[3,2‐a]pyrimidine‐3,5,7(6H)‐trione

2H‐Thiazolo[3,2‐a]pyrimidine‐3,5,7(6H)‐trione ( 2 ) was synthesized and characterized via molecular quantum parameters using the PM3‐semiempirical MO method. This is considered the only route not previously reported in the literature to synthesize compound 2 from 2‐imino‐4‐thiazolidinone ( 1 ).     

Maximizing the Potency of siRNA Lipid Nanoparticles for Hepatic Gene Silencing In Vivo

Special (lipid) delivery: The role of the ionizable lipid pK(a) in the in?vivo delivery of siRNA by lipid nanoparticles has been studied with a large number of head group modifications to the lipids. A tight correlation between the lipid pK(a) value and silencing of the mouse FVII gene (FVII ED(50) ) was found, with an optimal pK(a) range of 6.2-6.5. The most potent cationic lipid from this study has ED(50) levels around 0.005?mg?kg(-1) in mice and less than 0.03?mg?kg(-1) in non-human primates.     

Erratum to: ”Selective separation of some ecotoxic transition metal ions from aqueous solutions using immobilized macrocyclic material containing solid phase extraction system”

The original version of the article was published in Cent. Eur. J. Chem. 9(6) (2011), pp 1019–1026. Unfortunately, the original version of this article contains mistakes in the body of Fig. 1. Here we display the corrected version of the Fig. 1.     

Spectral decomposition and matrix-valued orthogonal polynomials

The relation between the spectral decomposition of a self-adjoint operator which is realizable as a higher order recurrence operator and matrix-valued orthogonal polynomials is investigated. A general construction of such operators from scalar-valued orthogonal polynomials is presented. Two examples of matrix-valued orthogonal polynomials with explicit orthogonality relations and three-term recurrence relation are presented, which both can be considered as 2×2-matrix-valued analogues of subfamilies of Askey–Wilson polynomials.     

The use of additive composition in arithmetic: the case of children classified as low attainers

This study investigated the conceptual understanding that low-attaining children have and are able to use in arithmetic. Fifteen 6–7 year old children solved pairs of conceptually-related addition problems. Conceptual relations between equal problems were constructed to reflect aspects of the principle of additive composition. Children's conceptual understanding was explored by examining their capability to use concept-based approaches in related problems, and ability to recognise and explain additive composition relationships. The findings indicate that, when prompted, children who employ only basic calculation procedures have the capability to recognise and use additive composition relations in problem solving. Almost all children showed increased sensitivity to additive composition relations when asked to explain the equality between related problems. Our findings highlight the need to develop pedagogical approaches that instigate low-attaining children's conceptual capabilities and support the operationalisation of these in the kinds of concept-based strategies that are most typically ascribed to high-attaining children.     

Asymptotics of generalized derangements

An adaptive wavelet-based method is proposed for solving TV(total variation)–Allen–Cahn type models for multi-phase image segmentation. The adaptive algorithm integrates (i) grid adaptation based on a threshold of the sparse wavelet representation of the locally-structured solution; and (ii) effective finite difference on irregular stencils. The compactly supported interpolating-type wavelets enjoy very fast wavelet transforms, and act as a piecewise constant function filter. These lead to fairly sparse computational grids, and relax the stiffness of the nonlinear PDEs. Equipped with this algorithm, the proposed sharp interface model becomes very effective for multi-phase image segmentation. This method is also applied to image restoration and similar advantages are observed.     

Effect of gamma irradiation on thermoluminescence and thermodynamic parameters of LiKSO4 doped with Nd2 O3

Abstract

The thermoluminescence and thermo-dynamic parameters of LiKSO₄: Nd were investigated. The effect of Nd dopant concentration in the range 0.1-1% as well as that of γ-irradiation dose in the range 56.3-3.24 × 10⁵ Gy were studied. The glow curves of the material are characterized by a double peak; each behaving seperately with radiation dose. The highest TL enhancement was obtained for Nd concentration of 0.5%; while irradiation dose of few hundreds Gy gave the best TL response. The thermodynamic parameters of LiKSO₄ doped with 0.5% Nd decreased with radiation dose up to about 5000 Gy.