Removal of Basic Blue 3 by sorption onto a weak acid acrylic resin

A weak acid acrylic resin was used as an adsorbent for the investigation of Basic Blue 3 (BB3) adsorption kinetics, isotherms, and thermodynamic parameters. Batch adsorption studies were carried out to evaluate the effect of pH, contact time, initial concentration (28–100 mg/g), adsorbent dose (0.05–0.3 g), and temperature (290–323 K) on the removal of BB3. The adsorption equilibrium data were analyzed by the Langmuir, Temkin, and Freundlich isotherm models, with the best fitting being the first one. The adsorption capacity (Q_o) increased with increasing initial dye concentration, adsorbent dose, and temperature; the highest maximum Q_o (59.53 mg/g) was obtained at 323 K. Pseudo‐first‐order and pseudo‐second‐order kinetic models and intraparticle diffusion models were used to analyze the kinetic data; good agreement between the experimental and calculated amounts of dye adsorbed at equilibrium were obtained for the pseudo‐second‐order kinetic models for the entire investigated concentrations domain. Various thermodynamic parameters, such as standard enthalpy of adsorption (ΔH^o = 88.817 kJ/mol), standard entropy of adsorption (ΔS^o = 0.307 kJ mol^?1 K^?1), and Gibbs free energy (ΔG^o < 0, for all temperatures investigated), were evaluated and revealed that the adsorption process was endothermic and favorable. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Study of the atypical formations in the corrosion bulks of an ancient bronze shield,by optical and electron microscopy

This article presents the atypical formations in the structure of the corrosion crust and in the partially mineralized metallic core, which resulted during the underground stay of a bronze shield, dated between the 1st century B.C. and the 1st century A.D. For our study, we choose a representative fragment from the rim of the shield, which was analyzed by optical microscopy and by electron microscopy coupled with energy‐dispersive X‐ray spectroscopy, to study its morphology, its composition, and the location of chemical compounds on the surface and inside the bulk formed during the underground stay, by processes of chemical and physical alteration, assisted by contamination with structural elements from the site. Those processes, by monolithization and mineralization formed a series of structures consisting of congruent elements and phases with a complex composition. Those formations, defined as surface effects generated by exogenous factors and endogenous factors inside the bulk, are frequently found in ancient bronze objects (such as the exterior flat mole formations and the Liesegang effect in the stratigraphic structure of the bulk). Some of those structures have atypical characteristics as regards their structure, composition, and formation mechanism, which may be used in archeometry. Moreover, that includes the object in the category of special cases, in terms of artifact evolution during underground stay and of the atypical formations resulted from the action of pedological and environmental factors. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

The Study on Molecular Profile Changes of Pathogens via Zinc Nanocomposites Immobilization Approach

The most critical group of all includes multidrug resistant bacteria that pose a particular threat in hospitals, as they can cause severe and often deadly infections. Modern medicine still faces the difficult task of developing new agents for the effective control of bacterial-based diseases. The targeted administration of nanoparticles can enhance the efficiency of conventional pharmaceutical agents. However, the interpretation of interfaces’ interactions between nanoparticles and biological systems still remains a challenge for researchers. In fact, the current research presents a strategy for using ZnO NPs immobilization with ampicillin and tetracycline. Firstly, the study provides the mechanism of the ampicillin and tetracycline binding on the surface of ZnO NPs. Secondly, it examines the effect of non-immobilized ZnO NPs, immobilized with ampicillin (ZnONPs/AMP) and tetracycline (ZnONPs/TET), on the cells’ metabolism and morphology, based on the protein and lipid profiles. A sorption kinetics study showed that the antibiotics binding on the surface of ZnONPs depend on their structure. The efficiency of the process was definitely higher in the case of ampicillin. In addition, flow cytometry results showed that immobilized nanoparticles present a different mechanism of action. Moreover, according to the MALDI approach, the antibacterial activity mechanism of the investigated ZnO complexes is mainly based on the destruction of cell membrane integrity by lipids and proteins, which is necessary for proper cell function. Additionally, it was noticed that some of the identified changes indicate the activation of defense mechanisms by cells, leading to a decrease in the permeability of a cell’s external barriers or the synthesis of repair proteins.     

Plasticity of brittle epoxy resins during debonding failures

A remarkably high degree of plasticity in brittle epoxies during debonding failures is reported. The plasticity is exhibited by the presence of ridges on the debonded surfaces having a width and height above the general level of these surfaces of the order of 100 nm. The surfaces of the more rigid substrates from which the debonding has occurred, by contrast, are smooth after debonding. The ridges have been found in several forms: in more or less straight rows parallel to the debonding fracture direction; as irregularly-shapes rings or craters, probably formed from secondary crack growth; as paraboloids, which also seem to be related to secondary crack growth; and as serpentine rows more or less perpendicular to the debonding fracture direction. This behaviour has been exhibited by various epoxy formulations. The 100 nm widths and heights for the ridges suggest that during debonding, plastic deformation has occurred rather uniformly in the epoxy to a depth below the interface of this order. This behaviour is in contrast to the simple notion of brittle fracture, in which atoms or molecules separate across planes in an elastically strained body. It differs also from the bulk fracturing process with these resins, in which a smaller amplitude, more random ridge and groove texture, referred to as the basic longitudinal or fingering texture, is seen.     

Constraint solving for interpolation

Interpolation is an important component of recent methods for program verification. It provides a natural and effective means for computing the separation between the sets of ‘good’ and ‘bad’ states. The existing algorithms for interpolant generation are proof-based: They require explicit construction of proofs, from which interpolants can be computed. Construction of such proofs is a difficult task. We propose an algorithm for the generation of interpolants for the combined theory of linear arithmetic and uninterpreted function symbols that does not require a priori constructed proofs to derive interpolants. It uses a reduction of the problem to constraint solving in linear arithmetic, which allows application of existing highly optimized Linear Programming solvers in a black-box fashion. We provide experimental evidence of the practical applicability of our algorithm.     

Surface Modification of Alumina/ Zirconia Ceramics Upon Different Fluoride‐Based Treatments

The aim of this study was to prepare and to characterize the structure of Al₂O₃–3YSZ composites with 5% TiO₂ addition as well as the surface modification upon treatments with SnF₂ and NaBF₄, respectively. SEM micrographs showed the controlled densification of the composites as an effect of 3YSZ and TiO₂ addition to alumina matrix. By FTIR and XRD, the characteristics of Al‐O and Zr‐O vibrations, respectively, the diffractions lines related to α‐corundum and zirconia in tetragonal phase were discussed. Qualitative and quantitative results obtained by XPS and ATR FTIR demonstrated that the proposed materials are more sensitive to SnF₂ than to NaBF₄ treatment.     

Optical properties of some new azo photoisomerizable bismaleimide derivatives

Novel polythioetherimides bearing azobenzene moieties were synthesized from azobismaleimides and bis-2-mercaptoethylether. Kinetics of trans-cis photoisomerization and of thermal conversion of cis to trans isomeric forms were investigated in both polymer solution and poly(methyl methacrylate) doped films using electronic absorption spectroscopy. Thermal recovery kinetics is well described by a two-exponential relation both in solution and polymer matrix, while that of low molecular weight azobismaleimide fit a first-order equation. The photoinduced cis-trans isomerization by visible light of azobenzene chromophores was examined in solution and in polymer films. The rate of photoinduced recovery was very high for azobismaleimides.     

Thermal and mechanical characterization of maleimide‐functionalized copoly(urethane‐urea)s

Maleimide functionalized copoly(urethane‐urea)s were prepared by the reaction of a binary mixture of dibenzyldiisocyanate and 5‐maleimidoisophthalic diisocyanate with a macrodiol (PEGA‐2000), using diethylene glycol and trimethylol‐propane as chain extender and crosslinkers in toluene‐dichloromethane solutions at the ratio NCO/OH = 1.2. Structures of polymers were confirmed by IR spectroscopy and properties were studied by thermal and mechanical analysis (dynamic mechanical analysis (DMA), differential scanning calorimetry, thermogravimetric analysis, stress‐strain) and other physical methods. Maleimide modification increased the storage modulus and Young's modulus of copoly(urethane‐urea)s, slightly increased their glass transition temperature from ?10.6°C to ?6.3°C. Copoly(urethane‐urea) networks obtained by thermal polymerization of maleimide functions showed significantly increased of the mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009