Boundary operator from matrix field formulation of boundary conditions for Friedrichs systems

Following the recent progress in understanding the abstract setting for Friedrichs symmetric positive systems by Ern, Guermond and Caplain (2007) [8], as well as Antoni? and Burazin (2010) [3], an attempt is made to relate these results to the classical Friedrichs theory.A comparison of two approaches, via the trace operator and the boundary operator, has been made, favouring the latter. Finally, a particular set of sufficient conditions for a boundary matrix field to define a boundary operator in that case is given, and the applicability of this procedure in realistic situations is shown by examples.     

Dinuclear Cobalt Complexes with a Decadentate Ligand Scaffold: Hydrogen Evolution and Oxygen Reduction Catalysis

A new decadentate dinucleating ligand containing a pyridazine bridging group and pyridylic arms has been synthesized and characterized by analytical and spectroscopic techniques. Four new dinuclear cobalt complexes featuring this ligand have been prepared and thoroughly characterized both in the solid state (X‐ray diffraction) and in solution (1D and 2D NMR spectroscopy, ESI‐MS, and electrochemical techniques). The flexible but stable coordination environment provided by the ligand scaffold when coordinating Co in different oxidation states is shown to play a crucial role in the performance of the set of complexes when tested as catalysts for the photochemical hydrogen evolution reaction (HER) and chemical oxygen reduction reaction (ORR).     

Ginzburg–Landau modelling of precursor nanoscale textures in ferroelastic materials

A Ginzburg–Landau free-energy model is proposed to study spatially inhomogeneous states that often occur as precursors of ferroelastic/martensitic transitions. Disorder is included in the harmonic coefficient of the free-energy density which gives rise to a spatial distribution of transition temperatures, and lattice integrity is imposed through Saint-Vénant compatibility conditions which lead to a long-range anisotropic elastic interaction. We show that precursor textures are a result of the competition between elastic anisotropy and disorder. Cross-hatched modulations (tweed patterns) take place for temperatures above the martensitic phase in the limit of high anisotropy and/or low disorder while a nano-cluster phase-separated state occurs at low anisotropies or high disorder. In the latter case, nanoscale inhomogeneities give rise to glassy behaviour while the structural transition is inhibited. Interestingly, in this case, the ferroelastic system also displays a large thermo-mechanical response so that the low-symmetry structure can be easily induced by the application of relatively small stresses within a broad temperature range.     

Sarracenia alata (Alph.Wood) Alph.Wood Microcuttings as a Source of Volatiles Potentially Responsible for Insects’ Respond

Rare carnivorous plants representing the genus Sarracenia are perceived as very interesting to scientists involved in various fields of botany, ethnobotany, entomology, phytochemistry and others. Such high interest is caused mainly by the unique capacity of Sarracenia spp. to attract insects. Therefore, an attempt to develop a protocol for micropropagation of the Sarracenia alata (Alph.Wood) Alph.Wood, commonly named yellow trumpets, and to identify the specific chemical composition of volatile compounds of this plant in vitro and ex vivo was undertaken. Thus, the chemical volatile compounds excreted by the studied plant to attract insects were recognized with the application of the headspace solid-phase microextraction (HS-SPME) coupled with the GC-MS technique. As the major volatile compounds (Z)-3-hexen-1-ol (16.48% ± 0.31), (E)-3-hexen-1-ol acetate (19.99% ± 0.01) and β-caryophyllene (11.30% ± 0.27) were identified. Further, both the chemical assumed to be responsible for attracting insects, i.e., pyridine (3.10% ± 0.07), and whole plants were used in in vivo bioassays with two insect species, namely Drosophila hydei and Acyrthosiphon pisum. The obtained results bring a new perspective on the possibilities of cultivating rare carnivorous plants in vitro since they are regarded as a valuable source of bioactive volatile compounds, as including ones with repellent or attractant activity.     

A Self‐Improved Water‐Oxidation Catalyst: Is One Site Really Enough?

The homogeneous catalysis of water oxidation by transition‐metal complexes has experienced spectacular development over the last five years. Practical energy‐conversion schemes, however, require robust catalysts with large turnover frequencies. Herein we introduce a new oxidatively rugged and powerful dinuclear water‐oxidation catalyst that is generated by self‐assembly from a mononuclear catalyst during the catalytic process. Our kinetic and DFT computational analysis shows that two interconnected catalytic cycles coexist while the mononuclear system is slowly and irreversibly converted into the more stable dinuclear system: an extremely robust water‐oxidation catalyst that does not decompose over extended periods of time.     

Nano-titanium oxide doped with gold,silver, and palladium — synthesis and structural characterization

Nano-titania doped with noble metals (Au/TiO₂, Ag/TiO₂, Pd/TiO₂) has been synthesized by mild hydrolysis of the mixture of metal salts or complexes and titanium isopropoxide ((iPr-O)₄Ti). After thermal decomposition of the obtained precursors, nanomaterials were formed. Morphological characterization of the nanomaterials was provided by scanning electron microscopy (SEM) and stereological analysis, determining the BET specific surface area, and BJH nanoporosity (pore volume, pore size). It has been found that the structure of nanomaterials (size of nanoparticles and agglomerates) depended strongly on the method of the (iPr-O)₄Ti hydrolysis. A minor dependence on the kind of solvents and precursors of noble metals was observed. The presence of doping metal nanoparticles was confirmed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). Nanomaterial phases were identified by X-ray diffraction (XRD). According to the XRD patterns, Ag/TiO₂ and Pd/TiO₂ products with doping metals in their oxidized form contain Ag-Ti and Pd-Ti phases. Peaks of the metal oxides Ag₂O and PdO are absent in the XRD patterns. The average size of TiO₂ nanoparticles is situated in the region of 20–60 nm, whereas metals are present as about 10–15 nm sized particles and fine nanoparticles.     

Passive sampling application to control air quality in interior of new vehicles

The investigation of air pollution is a highly important field of research. Air quality in a vehicle’s interior has attracted growing attention since people spend much of their time in vehicles and those frequently travelling in new cars are exposed to harmful compounds. The main air pollutants inside new vehicles are volatile organic compounds (VOCs), present as a result of interior materials’ de-gassing. Among the sampling methods used in indoor air quality research, active sampling for VOCs collection is one method that has been extensively described and applied. The present study sought to implement passive sampling with Radiello® samplers to collect air samples directly in the car factory. The results from passive sampling were compared with results derived from active sampling using Carbograph 1TD and silicagel coated with 2,4-dinitrophenylhydrazine cartridges, based on previously validated methods. The identification and quantification of organic compounds was performed using gas chromatography with flame ionisation coupled with a mass spectrometer after thermal desorption. Aldehydes were determined by means of high-performance liquid chromatography. In the present study, the results obtained with the use of active and passive methods of air sampling were compared, correlations between the two sampling methods were designated and the repeatability of passive sampling was detailed.