Metal hydride hydrogen storage and compression systems for energy storage technologies

Along with a brief overview of literature data on energy storage technologies utilising hydrogen and metal hydrides, this article presents results of the related R&D activities carried out by the authors. The focus is put on proper selection of metal hydride materials on the basis of AB₅- and AB₂-type intermetallic compounds for hydrogen storage and compression applications, based on the analysis of PCT properties of the materials in systems with H₂ gas. The article also presents features of integrated energy storage systems utilising metal hydride hydrogen storage and compression, as well as their metal hydride based components developed at IPCP and HySA Systems.     

Efficient and Long Lived Green Light‐Emitting Electrochemical Cells

The combination of high efficiencies and long lifetime in a single light‐emitting electrochemical cell (LEC) device remain a major problem in LEC technology, preventing its application in commercial lighting devices. Three green light‐emitting cationic iridium‐based complexes of the general composition [Ir(C^{^}N)₂(N^{^}N)][PF₆] with 4‐Fppy (2‐(4‐fluorophenyl)pyridinato) as the cyclometalating C^{^}N ligand and 1,10‐phenanthroline ( 1 ), 4,7‐diphenyl‐1,10‐phenanthroline (bathophenanthroline, bphen, 2 ), and 2,9‐dimethyl‐4,7‐diphenyl‐1,10‐phenanthroline (bathocuprione, dmbphen, 3 ) as ancillary N^{^}N ligands are synthesized and characterized. Computational studies are carried out in order to compare the electronic structure of the three ionic transition metal complexes (iTMCs) and provide insights into their potential as LEC emitter materials. LECs are then fabricated with complexes 1 – 3 . Driven under a pulsed current, they display a high luminance and current and power efficiencies. As the LEC based on complex 2 displays the overall best device performance, including the longest lifetime of 474 h, it is selected for subsequent driving conditions optimization. An extraordinary power efficiency of 25 lm W^?1 and current efficiency of 30 cd A^?1 are achieved under optimized operation conditions with reduced current density, resulting in a long device lifetime of 720 h. Altogether, ligand design in iTMCs and optimization of the device driving conditions leads to a significant improvement in LEC performance.     

Immobilization of radiotoxic elements with Y-stabilized zirconia: The thorium case

Y-stabilized zirconia (YSZ) phases were found to incorporate Th atoms, and the corresponding solubility ranges depend on the relative Y content. For the tetragonal phases with a lower Y concentration of 14 at.%, a maximal possible Th intake on the Zr/Y metal site reached ca. 10.3 at.%. Cubic phases with higher Y content could dissolve 11 at.% Th in an equilibrium state and up to ca. 12.3 at.% Th under nonequilibrium conditions. Larger Th–Zr/Y solubility range for phases with higher Y concentration was found to be related to the associated symmetry increase, as concluded from synchrotron radiation powder diffraction data. Specifically, the introduction of Th into tetragonal YSZ induces evolution toward higher cubic symmetry via flattening of the Zr/YO₈ polyhedra. In addition, a tetragonal YSZ crystal lattice exhibits strongly anisotropic expansion with a concomitant decrease in tetragonality upon the intake of Th. This results in an easier accommodation of bigger Th atoms via a structural stabilization of longer Zr/Y–O bonding distances which yields more symmetrical coordination of central Zr/Y metal ions by surrounding O atoms. Cubic symmetry is, therefore, more favorable to the incorporation of large tetravalent actinide elements.     

Analysis of amplitude- and phase-frequency characteristics of oscillating bubble system with closed measuring cell

Equations for the amplitude- and phase-frequency characteristics of oscillating bubble systems in a closed measuring cell are derived which are in a good qualitative agreement with experiments performed under ground and microgravity conditions (STS-95 and STS-107). Using calibration experiments with the pure solvent water it was possible to obtain the complex surface elasticity modulus from the respective experimental characteristics. The comparison of the high frequency limits of the measured elasticity with the theoretical dilational elasticities calculated according to the respective adsorption isotherm shows good agreement at small surfactant concentrations but large discrepancies at higher concentrations.     

3-D dynamic interaction between a penny-shaped crack and a thin interlayer joining two elastic half-spaces

Three-dimensional (3-D) elastodynamic interaction between a penny-shaped crack and a thin elastic interlayer joining two elastic half-spaces is investigated by an improved boundary integral equation method or boundary element method. The penny-shaped crack is embedded in one of the half-spaces, perpendicular to the interlayer and subjected to a time-harmonic tensile loading on its surfaces. Effective “spring-like” boundary conditions are applied to approximate the effects of the thin layer in the mathematical model. Integral representations for the displacement and the stress components are derived by using modified Green’s functions, which satisfy the “spring-like” boundary conditions identically. Then, application of the dynamic loading condition on the crack-surfaces results in a boundary integral equation (BIE) for the crack-opening-displacement over the crack-surfaces only. A solution procedure is developed for solving the BIE numerically. Numerical results for the mode-I dynamic stress intensity factor (SIF) are presented and discussed to show the variations of the mode-I dynamic SIF with the angular coordinate of the crack-front points, the dimensionless wave number, the material mismatch and the crack-layer distance.     

Synthesis of carbon nanostructures by arc evaporation of graphite rods with Co-Ni and YNi2 catalysts

Yields of single-walled carbon nanotubes (SWNTs) produced from electric arc evaporation of graphite electrodes with 3Co/Ni and YNi₂ catalysts differ substantially. For instance, with YNi₂ catalyst, the SWNT yield is ∼30-50 wt.% in ‘collar’ soot and ∼10-15 wt.% in ‘wall’ soot, while with 3Co/Ni catalyst, the yields are ∼15-20 wt.% and 2-3 wt.%, respectively. According to Raman spectroscopy data, the average dimension of SWNTs is ∼1.2 nm for 3Co/Ni and ∼1.4 nm for YNi₂ catalyst. Optimum conditions for synthesis also differ for catalysts compared; namely, for 3Co/Ni: current intensity is 93 A, helium pressure is 650 Torr, the electrode gap is 2.5-3 mm; for YNi₂: current intensity is 98 A, helium pressure is 500 Torr, the electrode gap is 1-2 mm.     

Ethylbenzene formation and its conversion towards coke in the side-chain methylation of toluene on a basic X zeolite

Journal of Porous Materials - Side-chain alkylation of toluene with methanol was realized on a strongly basic X-type zeolite which does not contain Brønsted acid sites under short contact time...     

Prediction of wear-resistant thin diffusive coatings

Friction and wear process are investigated using experimental data and mathematical modeling of the specimen contact interaction. To study the wear in the system, ‘a rigid punch—thin coating—elastic base’, a mathematic statement of the problem was formulated. The integral equations were obtained and the solutions to the problems for punches, containing parabolic and wedge-shaped profiles, and also with a flattened basis were constructed. New regularities of deformation and wear of thin coatings on solids were obtained. The methods for crack growth resistance calculations in the coatings allow us to predict by the physicochemical, tribotechnical and geometrical characteristics the coatings life-time, which is proved experimentally on chromium-based coatings applied on carbon steels.     

Crosslinking agents of unsaturated polymers: evaluation of the agent efficiency

We have performed a comparison of efficacy of several curing agents. We have synthesized curing agents with C=C-bonds of allylic, acrylic or peroxide group type, as derivatives of pyromellitic acid: diallylic ester (I), tetraallylic ester (II), di-(2-methacryloyloxyethyl)-pyromellitate (III), tetra-(2-methacryloyloxyethyl)pyromellitate (IV), ditert-butylperoxypyromellitate (V) and tetratert-butylperoxypyromellitate (VI). The possibility to use these agents for curing an unsaturated film-forming copolymer which contains polybutadiene fragments was investigated. The unsaturated curing agents (I–IV) are able to form crosslinked copolymers in the presence of peroxide initiators such as benzoyl peroxide. The gelation process orders as well as the values of the effective activation energies for all curing agents studied have been determined. In the presence of curing agents of methacrylic type (III–IV) the crosslinking proceeds more rapidly than in the presence of allylic esters. Unsaturated curing agents containing carboxylic groups (I, III) promote faster formation of three-dimensional structures than tetra-substituted derivatives of pyromellitic acid. For curing agents of the peroxide type the inverse relation is observed. The hardness of films obtained using carboxylic curing agents is higher than for noncarboxylic ones. Films obtained in the presence of unsaturated curing agents exhibit higher hardness than those obtained in the presence of peroxide agents. Electronic Publication     

Open-source hardware- and software-based cryomicroscopy system for investigation of phase transitions in cryobiological research

The development of inexpensive equipment adapted for the study of a specific biological object is very important for cryobiology. In the presented work, we have proposed a simple system for microscopy utilising open-source platform Arduino. Testing this system showed that it had sufficient sensitivity to determine the physical processes occurring in a cryopreserved sample such as intra- and extracellular water crystallisation and salt eutectic. Utilising this system, we investigated the mechanisms of cryoprotection and cryodamage of testis interstitial cells (ICs) in cryoprotective media, which included cryoprotective agents such as dimethyl sulphoxide (Me₂SO), as well as foetal bovine serum or polymers (dextran, hydroxyethyl starch and polyethylene glycol). It was shown that a serum-/xeno-free medium that included 0.7 M Me₂SO and 100 mg/mL dextran was able to reduce intracellular water crystallisation in cells, change the structure of extracellular ice, and reduce salt eutectic and recrystallisation. All these effects correlated with better IC survival after cryopreservation in the medium. This medium is potentially less toxic as it has lower concentrations of Me₂SO compared to serum-containing media developed for cryopreservation of testicular cells. This would pave a way for the creation of nontoxic serum-free compositions that does not require removal before use of cryopreserved living cells for laboratory practice or in clinics.