Single-ion-conducting nanocomposite polymer electrolytes based on PEG400 and anionic nanoparticles: Part 1. Synthesis,structure and properties

The synthesis and the properties of single-ion-conducting nanocomposite polymer electrolytes (nCPEs) are described. The nCPEs are obtained by doping polyethylene glycol 400 (PEG400) with different amounts of a fluorinated TiO₂-based nanofiller (LiFT^®) that is surface-functionalized with Li⁺ cations. Electrolytes with general formula [PEG400/(LiFT)_y] and y = n_Ti/n_PEG ranging from 0 to 26.4 are obtained. The materials are characterized by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Fourier-Transform Infrared Spectroscopy in both the medium (FT-MIR) and far infrared (FT-FIR). In the [PEG400/(LiFT)_y] electrolytes the concentration of LiFT nanofiller strongly affects the thermal stability and transitions of PEG400. In addition, vibrational measurements allow us to reveal the interactions occurring between: (a) different PEG400 chains; (b) PEG400 and Li⁺ cations; and (c) PEG400 and LiFT nanoparticles (NPs). On LiFT nanofiller concentration, results show three compositional regions in [PEG400/(LiFT)_y] electrolytes which are correlated to the presence of three different interaction environments between LiFT NPs and PEG400 chains.     

Cohesive-zone-model formulation and implementation using the symmetric Galerkin boundary element method for homogeneous solids

A new symmetric boundary integral formulation for cohesive cracks growing in the interior of homogeneous linear elastic isotropic media with a known crack path is developed and implemented in a numerical code. A crack path can be known due to some symmetry implications or the presence of a weak or bonded surface between two solids. The use of a two-dimensional exponential cohesive law and of a special technique for its inclusion in the symmetric Galerkin boundary element method allows us to develop a simple and efficient formulation and implementation of a cohesive zone model. This formulation is dependent on only one variable in the cohesive zone (relative displacement). The corresponding constitutive cohesive equations present a softening branch which induces to the problem a potential instability. The development and implementation of a suitable solution algorithm capable of following the growth of the cohesive zone and subsequent crack growth becomes an important issue. An arc-length control combined with a Newton–Raphson algorithm for iterative solution of nonlinear equations is developed. The boundary element method is very attractive for modeling cohesive crack problems as all nonlinearities are located along the boundaries (including the crack boundaries) of linear elastic domains. A Galerkin approximation scheme, applied to a suitable symmetric integral formulation, ensures an easy treatment of cracks in homogeneous media and excellent convergence behavior of the numerical solution. Numerical results for the wedge split and mixed-mode flexure tests are presented.     

Influence of taro (Colocasia esculenta L. Shott) growth conditions on the phenolic composition and biological properties

Colocasia esculenta (L.) Shott, commonly known as taro, is an essential food for millions of people. The leaves are consumed in sauces, purees, stews, and soups, being also used in wound healing treatment. Nowadays, the consumers’ demand for bioactive compounds from the diet led to the development of new agricultural strategies for the production of health-promoting constituents in vegetables. In this work, two strategies (variety choice and irrigation conditions) were considered in the cultivation of C. esculenta. The effect on the phenolic composition of the leaves was evaluated. Furthermore, a correlation between the biological activity of the different varieties and their chemical composition was established. Qualitative and quantitative differences in the phenolic composition were observed between varieties; furthermore, the irrigation conditions also influenced the composition. C. esculenta varieties were able to scavenge several oxidant species and to inhibit hyaluronidase, but data suggest that metabolites other than phenolics are involved. The results show that cultivation strategies can effectively modulate the accumulation of these types of bioactive compounds. Furthermore C. esculenta wound healing potential can be attributed, at least in part, to the protection of the wound site against oxidative/nitrosative damage and prevention of hyaluronic acid degradation.     

In Vitro and In Silico Characterization of an Antimalarial Compound with Antitumor Activity Targeting Human DNA Topoisomerase IB

Human DNA topoisomerase IB controls the topological state of supercoiled DNA through a complex catalytic cycle that consists of cleavage and religation reactions, allowing the progression of fundamental DNA metabolism. The catalytic steps of human DNA topoisomerase IB were analyzed in the presence of a drug, obtained by the open-access drug bank Medicines for Malaria Venture. The experiments indicate that the compound strongly and irreversibly inhibits the cleavage step of the enzyme reaction and reduces the cell viability of three different cancer cell lines. Molecular docking and molecular dynamics simulations suggest that the drug binds to the human DNA topoisomerase IB-DNA complex sitting inside the catalytic site of the enzyme, providing a molecular explanation for the cleavage-inhibition effect. For all these reasons, the aforementioned drug could be a possible lead compound for the development of an efficient anti-tumor molecule targeting human DNA topoisomerase IB.     

Polypropylene-based ferromagnetic composites

Microcomposites of polypropylene (PP) and magnetite (Fe₃O₄) in different concentration were prepared by one-step melt blending of magnetite powders and polypropylene. Morphology of the composites was studied by means of scanning electron microscope (SEM) to investigate magnetite dispersion within the polypropylene matrix. Thermoxidative stability and mechanical properties were investigated, showing improved thermal stability and enhanced stiffness. Magnetic properties characterization showed a ferromagnetic behavior with coercive field of 116 Oe and saturation magnetizations linearly dependent on the content of magnetic phase.     

Transportable automated ammonia sensor based on a pulsed thermoelectrically cooled quantum-cascade distributed feedback laser

A compact ammonia sensor based on a 10-microm single-frequency, thermoelectrically cooled, pulsed quantum-cascade laser with an embedded distributed feedback structure has been developed. To measure NH3 concentrations, we scanned the laser over two absorption lines of its fundamental v2 band. A sensitivity of better than 0.3 parts per million was achieved with just a 1-m optical path length. The sensor is computer controlled and automated to monitor NH3 concentrations continuously for extended periods of time and to store data in the computer memory.     

Surface modification and patterning using low-energy ion beams: Si-O bond formation at the vacuum/adsorbate interface.

Modification of hydroxyl-terminated self-assembled monolayer (HO-SAM) surfaces by collision of low-energy (15 eV) hyperthermal Si(CH3)3+ ions is shown to lead to Si-O bond formation and terminal trimethylsilyl ether formation. Modification was verified by in situ mass spectrometry using chemical sputtering with CF3+ ions (70 eV), ex situ secondary ion mass spectrometric analysis (12 kV Ga+ primary ion beam), and through X-ray photoelectron spectroscopy by monitoring Si (2s). The nature of the surface modification was further established by analysis of synthetic SAM surfaces made up of mixtures of the trimethylsilyl-11-mercapto-1-undecane ether and various proportions of the hydroxyl-terminated mercaptan (11-mercapto-1-undecanol). These mixed surfaces, as well as the spectroscopic data, indicate that ca. 30% of the hydroxyl chains are covalently modified at saturation coverage. Analogous surface transformations are achieved using Si(CH3)2F+ and Si(CH3)2C6H5+.     

A method to mimic and to study the release of flavour compounds from chewed food

A method for analysing the flavour release from chewed food has been developed. Flavour release is studied in an artificial mouth simulating the process of chewing and using fluid model systems, in our case aromatised oil in water emulsions. The fast transfer of volatile substances from the chewpulp into the gaseous phase is followed up by comparing six quickly taken gas samples. Volatile substances are analysed by means of a special technique which includes cryofocusing and capillary gas chromatography. As a wide spectrum of individual volatile substances is considered, systematic investigations into the flavour release from food under mouth-typical conditions are possible.