Calorimetric investigations of the influence of waste aluminosilicate on the hydration of different cements

The aim of this work is to compare the influence of addition of waste aluminosilicate catalyst on the initial periods of hydration of different cements, i.e. calcium aluminate cements of different composition and Portland cement, basing on the calorimetric studies. Cement pastes containing up to 25 mass% of additive were studied, where the water/(cement+additive) ratio was 0.5. An attempt was undertaken to explain the mechanism of action of introduced aluminosilicate in the system of hydrating cement, particularly in the case of calcium aluminate cement pastes. It was found that the presence of fine-grained additive caused in all studied cases the increase of the amount of released heat in the first period after the addition of water. In the case of aluminate cements with aluminosilicate addition, a significant reduction of induction time and faster precipitation of hydration products were observed compared to the reference sample (without additive). In the experimental conditions, the additive caused the acceleration of aluminate cements hydration, and the mechanism of its action is probably complex and can encompass: nucleative action of small grains and formation of new chemical compounds.     

Mid‐IR Spectroscopy and Structural Features of Protonated Carbonic Acid in the Gas Phase

An anti trihydroxycarbenium ion is revealed to be the gas‐phase structure of protonated carbonic acid by IR multiple‐photon dissociation spectroscopy (see picture for calculated structure and comparison of experimental and computed spectra). Deprotonation yields anti‐H₂CO₃ with a nominal gas‐phase basicity of 724 kJ mol^?1.

     

Thermodynamics of Carbon Dioxide Adsorption on the Protonic Zeolite H‐ZSM‐5

Adsorption of carbon dioxide on H‐ZSM‐5 zeolite (Si:Al=11.5:1) was studied by means of variable‐temperature FT‐IR spectroscopy, in the temperature range of 310–365 K. The adsorbed CO₂ molecules interact with the zeolite Brønsted‐acid OH groups bringing about a characteristic red‐shift of the O? H stretching band from 3610 cm^?1 to 3480 cm^?1. Simultaneously, the ν₃ mode of adsorbed CO₂ is observed at 2345 cm^?1. From the variation of integrated intensity of the IR absorption bands at both 3610 and 2345 cm^?1, upon changing temperature (and CO₂ equilibrium pressure), the standard adsorption enthalpy of CO₂ on H‐ZSM‐5 is ΔH⁰=?31.2(±1) kJ mol^?1 and the corresponding entropy change is ΔS⁰=?140(±10) J mol^?1 K^?1. These results are discussed in the context of available data for carbon dioxide adsorption on other protonic, and also alkali‐metal exchanged, zeolites.     

Maize food allergy: lipid-transfer proteins,endochitinases, and alpha-zein precursor are relevant maize allergens in double-blind placebo-controlled maize-challenge-positive patients

Italian patients with maize anaphylaxis have been shown to have IgE toward two major maize allergens: an alpha-amylase inhibitor and a 9-kDa LTP. A complete study on maize food allergens in patients with positive maize double-blind, placebo-controlled food challenge (DBPCFC) is lacking. The objective was to utilize the three maize protein fractions to identify and characterize the most relevant IgE-binding proteins recognized by the sera of Italian and Swiss patients with either a positive maize-DBPCFC or a history of maize-induced anaphylaxis. Osborne’s protein fractions of maize were extracted to obtain water-soluble, total zein, and total protein fractions. Protein IgE-binding capacity was investigated by SDS-PAGE immunoblotting using the sera from DBPCFC-positive patients and from patients with maize-induced anaphylaxis. Purified maize LTP was used to inhibit the IgE immunoblotting of the three protein fractions. IgE immunoblotting demonstrated that the 9-kDa LTP was recognized by all the Italian patients and by none of the Swiss patients. Other allergens were: 14-kDa α-amylase inhibitor, 30-kDa endochitinases A and -B, 19 kDa zein-β precursor, and 26 kDa zein-α precursor; a newly described allergen, the globulin-2 precursor, identified in the total protein fraction. It is noteworthy that maize LTP and endochitinase were cross-reactive with grape LTP and one grape endochitinase. LTP was found to be the only major allergen in Italian patients with either positive maize challenge or a history of maize-induced anaphylaxis. We have identified other maize allergens in subjects with maize food allergy, as grape cross-reactive endochitinase, however, the clinical significance of these proteins needs to be investigated in larger groups of patients with allergy to these food items.     

Spectral theory for algebraic combinations of Toeplitz and composition operators

We determine the essential spectra of algebraic combinations of Toeplitz operators with continuous symbol and composition operators induced by a class of linear-fractional non-automorphisms of the unit disk. The operators in question act on the Hardy space H² on the unit disk. Our method is to realize the C^*-algebra that they generate as an extension of the compact operators by a concrete C^*-algebra whose invertible elements are easily characterized.     

Boundary optimal control of the Westervelt and the Kuznetsov equations

This paper is concerned with optimal Neumann boundary control for the Westervelt and the Kuznetsov equations, which are equations of nonlinear acoustics. Specifically, functionals of tracking type with applications in noninvasive ultrasonic medical treatments are considered. Existence of optimal controls is established and first order necessary optimality conditions are derived. Stability of the minimizer with respect to perturbations in the data as well as convergence of the controls when the regularization parameter tends to zero is shown.     

Replication and shortfall risk in a binomial model with transaction costs

The shortfall risk is defined as the optimal mean value of the terminal deficit produced by a self-financing portfolio whose initial value is smaller than what is required to replicate a contingent claim. In this paper we look for an explicit expression for it, as well as for the optimal strategy, when the market model is a binomial model with proportional transaction costs. We first study replication of European claims which satisfy suitable assumptions. We then investigate the shortfall minimization problem in a framework very similar to that without transaction costs. The author thanks the referee for useful comments on an earlier version of the present paper.     

Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of proteins in dry-cured hams: data registration and multivariate analysis across multiple gels

This study investigates whether dry-cured hams from two European countries can be distinguished using SDS-PAGE. Thirty-seven commercial hams (19 Spanish, 18 French) were used in the study. Four protein fractions were extracted from each sample, with sufficient material prepared to allow each fraction to be analysed in triplicate lanes. The complete extraction process was carried out in duplicate. The 24 specimens originating from each ham sample were randomly allocated to different lane positions and gels, as were at least two reference lanes (for reference proteins). In total, 118 gels were prepared. Mathematical routines were developed using a matrix language to process the gel image files. Procedures were written to carry out 'within-gel' image correction, lane extraction and normalization, 'between-gel' data registration and linear discriminant analysis (LDA) of each fraction's data to establish whether the provenance could be systematically distinguished. The between-gel registration was carried out using a genetic algorithm (GA). Feature selection was also performed using a GA, to pass subsets of features to the LDA routine. Cross-validated classification success rates were 84, 91, 81 and 85%, respectively, for the four fractions. We conclude that SDS-PAGE can be conducted in a sufficiently quantitative manner and can potentially verify the provenance of regional speciality dry-cured hams.     

Modification of surface properties of a poly(dimethylsiloxane)-based elastomer, RTV11, upon exposure to seawater

Atomic force microscopy (AFM) was combined with surface analytical techniques to investigate the rarely addressed issue of the effect of seawater on the surface properties of a selected fouling-release coating, silicon elastomer RTV11 (trademark of General Electric). The exposure of the RTV11 surface to seawater resulted in a modification of its morphology and mechanical properties, as confirmed by AFM and scanning electron microscopy (SEM). Surface modification was dependent on sample preparation and curing process, namely, curing agent concentration and relative humidity during curing. The RTV11 surface remained largely unaltered for samples cured under 100% relative humidity. SEM and X-ray photoelectron spectroscopy studies confirmed that the modified surface of RTV11 had the same elemental composition as the unexposed surface of the elastomer and showed excess Ca. However, the modified surface deformed plastically under load and was stiffer than the original surface. No major change was found on surfaces exposed to nanopure water during similar times of exposure as in seawater, regardless of curing conditions. The rate of increase in the aggregate formation in seawater can be described by an exponential function, with a decay constant of approximately 4.99 x 10(-)(3) min(-)(1) and a pre-exponential factor of approximately 1.77 x 10(-)(2) microm/min.     

Pegylated tetraarylporphyrin entrapped in liposomal membranes. A possible novel drug-carrier system for photodynamic therapy

A system of poly(ethylene glycol) bound tetraarylporphyrin entrapped in liposomal membranes was investigated. The interactions between the 5-(4-hydroxymethylphenyl)-10,15,20-tritolylporphyrin (Po) covalently attached to the poly(ethylene glycol) chain (PEG-Po), and phosphatidylcholine liposomes in the aqueous solution were studied. The adsorption of the investigated polymer to lipid vesicles was confirmed by measurements of dynamic light scattering and zeta potential. Experimental results demonstrate that the diameter of liposomes increased and the absolute value of the zeta potential decreased after addition of PEG-Po. The binding constants (K(b)) of Po chromophores to liposome in pH range from 5.2 to 9.0 were determined using fluorescence spectroscopy. The degree of binding was found to be pH-independent and the average value was 24.6 +/- 0.9 mg ml(-1). The acid-base properties of the porphyrin chromophores and their aggregation in an aqueous solution were also studied. pK values associated with imine-N protonation of the porphyrin core were found to be 2.59 and 0.68 at the ionic strength of 0.1 M. The equilibrium constant for dimerization, K(D), was found to be 5 x 10(3) M(-1).