Bifunctional Oxygen Reduction/Oxygen Evolution Activity of Mixed Fe/Co Oxide Nanoparticles with Variable Fe/Co Ratios Supported on Multiwalled Carbon Nanotubes.

A facile strategy is reported for the synthesis of Fe/Co mixed metal oxide nanoparticles supported on, and embedded inside, high purity oxidized multiwalled carbon nanotubes (MWCNTs) of narrow diameter distribution as effective bifunctional catalysts able to reversibly drive the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) in alkaline solutions. Variation of the Fe/Co ratio resulted in a pronounced trend in the bifunctional ORR/OER activity. Controlled synthesis and in-depth characterization enabled the identification of an optimal Fe/Co composition, which afforded a low OER/OER reversible overvoltage of only 0.831 V, taking the OER at 10 mA cm-2 and the ORR at -1 mA cm-2 . Importantly, the optimal catalyst with a Fe/Co ratio of 2:3 exhibited very promising long-term stability with no evident change in the potential for both the ORR and the OER after 400 charge/discharge (OER/ORR) cycles at 15 mA cm-2 in 6 m KOH. Moreover, detailed investigation of the structure, size, and phase composition of the mixed Fe/Co oxide nanoparticles, as well as their localization (inside of or on the surface of the MWCNTs) revealed insight of the possible contribution of the individual catalyst components and their synergistic interaction in the catalysis.

Soil-to-plant and soil-to-grain transfer of (137)Cs in field-grown maize hybrids during two contrasting seasons: assessing the phenotypic variability and its genetic component.

Field-grown maize hybrids were assessed for variability in (137)Cs accumulation in vegetative parts of young and mature maize shoots and grains during 2 years with contrasting climatic conditions. Trials were carried out at different sites in the Tula region of Russia, which is characterized by a highly homogenous soil classified as Luvic Chernozem according to FAO/UNESCO, and average contamination levels of about 509-564 Bq (137)Cs kg(-1) soil. In the first year, 19 hybrids were tested. The two hybrids with the highest and the two with the lowest (137)Cs concentration ratios (C (r)) were also tested in the second year, together with another 11 hybrids. All samples were additionally assessed for their potassium content. In both investigation periods (137)Cs accumulation in vegetative shoots and grains was found to vary up to more than twofold between hybrids. However, C (r) values of those hybrids that showed a relatively low (137)Cs accumulation in the first year were not necessarily low in the second year, and the ratio between the (137)Cs C (r) of low- and high-accumulating hybrids was much smaller than in the year before. In both vegetative shoots and grains the variance caused by the different years was larger than the genotypic variance, thus indicating the limits of genotype selection for this trait. Significant correlations were determined between the (40)K and (137)Cs C (r) values in the same tissue, but for one hybrid indications for uncoupling of the two traits were found. Average Cs/K ratios in young shoots, mature shoots and grains were 0.06, 0.05 and 0.02, respectively, indicating tissue- and stage-specific regulation of accumulation within each plant. The findings are discussed with respect to new approaches towards a better understanding of (137)Cs accumulation and its potential reduction in plants.

Methods for preparation of recombinant cytokine proteins V. mutant analogues of human interferon-gamma with higher stability and activity.

Mutant analogues of recombinant human immune interferon (IFN-gamma) with higher stability and biological activity were prepared. Depending on the analogue, protein structure modification might involve introduction of an intramonomer disulfide bond (through replacements of Glu7Cys and Ser69Cys), C-terminal shortening by 10 amino acid residues, as well as Gln133Leu substitution in truncated variant. Isolation, purification, and renaturation of the IFN-gamma analogues expressed in Escherichia coli as inclusion bodies were performed according to the scheme developed earlier for wild-type protein. The main idea of this scheme is to remove cellular impurities before recombinant protein renaturation. Folding kinetics of IFN-gamma was studied by reversed-phase HPLC. IFN-gamma and mutant proteins were characterized by their thermal stability and biological activity. Introduction of the intramolecular disulfide bond together with C-terminal shortening and replacement of C-terminal residue was shown to result in increasing the thermal stability by 19 degrees C and four times enhancement of biological activity compared with intact IFN-gamma molecule.

Immunocorrection Therapy: Drugs and Prospects.

The analysis has been made for the basic immunocorrection drugs, used in clinical practice. By their features, the drugs are divided into 6 groups: immunoactive structures of pathogens, polyelectrolites, inductors of IFN-alpha, thymic hormones and their analogs, bone marrow regulators (myelopeptides) and cytokines. The first 3 groups of drugs are characterized by the inductive mechanism of action, whereas thymic hormones, myelopeptides and cytokines by the substitutive mechanism. The substitutive immunomodulators are preferential drugs at the advanced stages of infection. Immunocorrection should be used by the adequate courses and under the control of clinical dynamics, immunogram or differential blood counts. Transplantation of heterologous tissues and organs, transfusion of blood cell fractions and the first trimester of gestation may be called as contraindications for administration of immunocorrection. The high clinical efficiency of immunocorrection is shown on the usage of leukinferon in an extremely severe human pathology, such as sepsis, complicated by syndrome of polyorgan insufficiency.