We report on the zinc oxide (ZnO) thin films obtained by the atomic layer deposition (ALD) method using diethyl zinc and water precursors, which allowed us to lower deposition temperature to below 200 °C. The so-obtained “as grown” ZnO layers are polycrystalline and show excitonic photoluminescence (PL) at room temperature, even if the deposition temperature was lowered down to 100 °C. Defect-related PL bands are of low intensity and are absent for layers grown at 140−200 °C. This is evidence that extremely low temperature growth by ALD can result in high quality ZnO thin films with inefficient nonradiative decay channels and with thermodynamically blocked self-compensation processes.

Four mechanisms previously proposed for dioxygen activation catalyzed by α-keto acid dependent oxygenases (α-KAO) were studied with dispersion-corrected DFT methods employing B3LYP and TPSSh functionals in combination with triple-ζ basis set (cc-pVTZ). The aim of this study was to revisit mechanisms suggested in the past decade and resolve remaining issues related to dioxygen activation. Mechanism A, which runs on the quintet potential energy surface (PES) and includes formation of an Fe(III)-superoxide radical anion complex, subsequent oxidative decarboxylation, and O-O bond cleavage, was found to be most likely. However, mechanism B taking place on the septet PES involves a rate limiting barrier comparable to the one found for mechanism A, and thus it cannot be excluded, though two other mechanisms (C and D) were ruled out. Mechanism C is a minor variation of mechanism A, whereas mechanism D proceeds through formation of a triplet Fe(IV)-alkyl peroxo bridged intermediate. The study covered also full optimization of relevant minimum energy crossing points (MECPs). The relative energy of critical intermediates was also studied with the CCSD(T) method in order to benchmark TPSSh and B3LYP functionals with respect to their credibility in predicting relative energies of septet and triplet spin states of the ternary enzyme-Fe-α-keto glutarate (α-KG)-O2 complex.

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Ring hydroxylation and coupled rearrangement reactions catalyzed by 4-hydroxyphenylpyruvate dioxygenase were studied with the QM/MM method ONIOM(B3LYP:AMBER). For electrophilic attack of the ferryl species on the aromatic ring, five channels were considered: attacks on the three ring atoms closest to the oxo ligand (C1, C2, C6) and insertion of oxygen across two bonds formed by them (C1-C2, C1-C6). For the subsequent migration of the carboxymethyl substituent, two possible directions were tested (C1→C2, C1→C6) and two different mechanisms were sought (step-wise radical, single-step heterolytic). In addition, formation of an epoxide (side)product and benzylic hydroxylation, as catalyzed by the closely related hydroxymandelate synthase, were investigated. From the computed reaction free energy profiles it follows that the most likely mechanism of 4-hydroxyphenylpyruvate dioxygenase involves electrophilic attack on the C1 carbon of the ring and subsequent singlestep heterolytic migration of the substituent. Computed values of the kinetic isotope effect for this step are inverse, consistent with available experimental data. Electronic structure arguments for the preferred mechanism of attack on the ring are also presented.

The authors demonstrate herein that by lowering of a growth temperature they can obtain ZnMnO layers with homogeneous Mn distribution, which are free of Mn accumulations and inclusions of foreign phases due to other Mn oxides. These layers (with low Mn content fractions) show paramagnetic phase in room temperature magnetization measurements. Contribution of a high temperature ferromagnetic phase is missing, which the authors relate to blocking of spinodal decomposition of ZnMnO under controlled growth conditions of atomic layer deposition.

The authors demonstrate that by lowering deposition temperature of ZnMnO films (T<500°C) they can avoid Mn clustering and creation of inclusions of Mn oxides, which are frequently formed in ZnMnO layers grown by high temperature methods. Low temperature growth is achieved using atomic layer deposition and organic zinc and manganese precursors.

In this article we compare the efficacy of different pharmacological agents (ranitidine, and omeprazole) to support phage transit from stomach to distal portions of the gastrointestinal tract in rats. We show that a temporal modification of environment in the animal stomach may protect Twort-like therapeutic antistaphylococcal phage A5/80 (from bacteriophage collection of the Hirszfeld Institute of Immunology and Experimental Therapy PAS in Wroclaw, Poland) from the inactivation by gastric juice effectively enough to enable a significant fraction of orally administered A5/80 to pass to the intestine. Interestingly, we found that yogurt may be a relatively strong in enhancing phage transit. Given the immunomodulating activities of phages our data may suggest that phages and yogurt can act synergistically in mediating their probiotic activities and enhancing the effectiveness of oral phage therapy. We also demonstrate that orally applied phages of similar size, morphology, and sensitivity to acidic environment may differ in their translocation into the bloodstream. This was evident in mice in which a therapeutic staphylococcal phage A5/80 reached the blood upon oral administration combined with antacid agent whilst T4 phage was not detected even when applied in 103 times higher dose. Our findings also suggest that phage penetration from digestive tract to the blood may be species-specific.

Hydroxymandelate synthase (HMS) and 4-hydroxyphenylpyruvate dioxygenase (HPPD) are highly related enzymes using the same substrates but catalyzing hydroxylation reactions yielding different products. The first steps of the HMS and HPPD catalytic reactions are believed to proceed in the same way and lead to an Fe(IV)═O-hydroxyphenylacetate (HPA) intermediate. Further down the catalytic cycles, HMS uses Fe(IV)═O to perform hydroxylation of the benzylic carbon, whereas in HPPD, the reactive oxoferryl intermediate attacks the aromatic ring of HPA. This study focuses on this part of the HMS catalytic cycle that starts from the oxoferryl intermediate and aims to identify interactions within the active site that are responsible for enzyme specificity. To this end, a HMS-Fe(IV)═O-HPA complex was modeled with molecular dynamics simulations. On the basis of the molecular dynamics-equilibrated structure, an active site model suitable for quantum chemical investigations was constructed and used for density functional theory (B3LYP) calculations of the mechanism of the native reaction of HMS, i.e., benzylic hydroxylation, and the alternative electrophilic attack on the ring, which is a step of the HPPD catalytic cycle. The most important result of this study is the finding that the conformation of the Ser201 side chain in the second coordination shell has a key role in directing the reaction of Fe(IV)═O into either the HMS or the HPPD channel.