EPR spectra of γ-irradiated dl-α-alanine supported on molecular sieves

The aim of the work was to collect information concerning boundary effects which are suspected in α-alanine dosimeters consisted of powdered microcrystalline α-alanine and binders. In our experiments the conventional binders were replaced by molecular sieves (MS). MS are inorganic porous materials (host structures) with well organized and uniform intra-crystalline pore systems of nano-scale size. The guest molecules can be either physically adsorbed on very large inner MS surface, or chemically bound to the active sites. They can be also encapsulated inside the intracrystalline cavities. The EPR spectra of gamma irradiated dl-α-alanine supported on NaY, CeY, SOD, mordenite, ZSM-5 and ALPO₄-5 were very similar to that one observed for irradiated microcrystalline dl-α-alanine. In the case of alanine supported on HY an initial EPR spectrum was different and only after some weeks it made resemble to the well known quintet observed in microcrystalline samples. In sodalites synthesized in the presence of dl-α-alanine EPR signal appeared in non-irradiated sample was very low and structureless. The irradiated sample showed a distinct spectrum which was quite different from that one observed for crystalline dl-α-alanine.     

Thermal and spectroscopic studies of sodium and light lanthanide (III) complexes with 2,4-pyridinedicarboxylate anion

Pyridine-2,4-dicarboxylic acid (lutidinic acid) is next one after pyridine-2,5-dicarboxylic acid of the six isomers which lanthanide complexes were studied thermally and spectrally. New complexes synthesized with light lanthanides (III) with general formula Ln₂L₃·nH₂O, where n?=?7.5; 8; 8.5; 9, were obtained. Sodium salt was obtained as hexahydrated compound. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), and Gd(III) are thermally stable up to 303?C313?K. Dehydration process run for all compounds in one stage, anhydrous compounds decompose through appropriate light lanthanides (III) oxalates, oxocarbonates, carbonates to metal oxides. Theoretical IR and Raman studies were carried out in order to identify precisely characteristic group bands vibrations present on IR and Raman spectra.     

The effect of manganese on the structural and surface properties of nanocrystalline cobalt catalyst for ammonia synthesis

Based on the active surface model of the iron catalyst for ammonia synthesis, the assumptions which led to obtaining the cobalt catalyst for ammonia synthesis were described. The incorporation into the system small amounts of manganese, an element which binds oxygen stronger than cobalt, has influence the development of the catalyst’s specific surface area. The activity of manganese modified catalysts is higher than that of cobalt catalyst without manganese addition. The obtained catalysts were characterized with the following methods: ICP-OES, XRD, BET      

Uncertainty relation for photons

The uncertainty relation for the photons in three dimensions that overcomes the difficulties caused by the nonexistence of the photon position operator is derived in quantum electrodynamics. The photon energy density plays the role of the probability density in configuration space. It is shown that the measure of the spatial extension based on the energy distribution in space leads to an inequality that is a natural counterpart of the standard Heisenberg relation. The equation satisfied by the photon wave function in momentum space which saturates the uncertainty relations has the form of the Schr?dinger equation in coordinate space in the presence of electric and magnetic charges.     

An influence of thermal treatment conditions of hydrotalcite-like materials on their catalytic activity in the process of N<Subscript>2</Subscript>O decomposition

Hydrotalcite-like materials containing apart from magnesium and aluminum also copper, cobalt, nickel, and iron were prepared by a co-precipitation method. Thermal transformations of hydrotalcite-like materials were studied by thermal analysis methods as well as XRD, UV–vis–DRS, and XPS measurements of the samples calcined at various temperatures (600, 700, and 800 °C). Calcined hydrotalcites, especially those containing cobalt and copper, were found to be active and selective catalysts of N₂O decomposition. It was shown that an increase in the calcination temperature significantly activated the Co-containing catalysts. Promotion of the samples with potassium resulted in activation of the hydrotalcite-based catalysts.     

Direct Synthesis of Double Hydrophilic Statistical Di‐ and Triblock Copolymers Comprised of Acrylamide and Acrylic Acid Units via the MADIX Process

Double hydrophilic statistical, diblock and triblock copolymers comprised of acrylamide and acrylic acid units have been synthesized in aqueous medium using the MADIX process. Starting from an either monofunctional or difunctional xanthate, the resulting AB and ABA‐type double hydrophilic block copolymers (DHBC) exhibited molar masses predetermined by the initial monomer/xanthate precursor molar ratio and polydispersity indices in the range 1.2–1.5. Batch copolymerizations yielded well‐defined statistical copolymers that were chain‐extended for the synthesis of novel poly‐ (acrylic acid‐stat‐acrylamide)‐block‐polyacrylamide DHBC.