Preliminary electrochemical studies of the flavohaemoprotein from Ralstonia eutropha entrapped in a film of methyl cellulose: Activation of the reduction of dioxygen

A flavohaemoprotein (FHP) from Ralstonia eutropha, obtained in a pure and active form, has been entrapped in a film of methyl cellulose on the electrode surface and gives a stable and reproducible electrochemical response at pH 7.00 when subject to cyclic voltammetry using a glassy carbon electrode. To our knowledge, no previous direct electrochemistry had been achieved with a bacterial flavohaemoglobin, which possess both a FAD and a haem. A single couple is observed which is assigned to the haem moiety of the protein, since the same result is obtained with a semi-apo form of the protein deprived of FAD (semi-apo FHP). The data collected were further confirmed by potentiometry with a platinum electrode, and the homogeneous electron transfer rate estimated by double potential step chronocoulometry at a bare glassy carbon electrode in the presence of methyl viologen (MV). The presence of FAD in the holoprotein is easily confirmed by UV-Vis spectrophotometry, but its expected electron relay role remains elusive. The protein activates the reduction of dioxygen by about 400 mV, the reduction current being proportional to the concentration of dioxygen up to 10% in volume in the gas mixture.     

Representations of the general linear group over symmetry classes of polynomials

Let V be the complex vector space of homogeneous linear polynomials in the variables x₁,..., x _m . Suppose G is a subgroup of S _m , and χ is an irreducible character of G. Let H _d (G, χ) be the symmetry class of polynomials of degree d with respect to G and χ.

For any linear operator T acting on V, there is a (unique) induced operator K _χ (T) ∈ End(H _d (G, χ)) acting on symmetrized decomposable polynomials by

$${K_\chi }\left( T \right)\left( {{f_1} * {f_2} * \cdots * {f_d}} \right) = T{f_1} * T{f_2} * \cdots * T{f_d}.$$

In this paper, we show that the representation T ? K _χ (T) of the general linear group GL(V) is equivalent to the direct sum of χ(1) copies of a representation (not necessarily irreducible) T ? B _χ ^G (T).

     

Time-gated luminescence microscopy with responsive nonmetal probes for mapping activity of protein kinases in living cells

A photoluminescence probe ARC-1185, possessing both high affinity towards basophilic protein kinases (PKs) and microsecond-scale luminescence lifetime when associated with a kinase, was used for the mapping of ARC-1185-PK complexes in living cells with time-gated luminescence microscopy.     

Qualitative and quantitative assessment of extracted oil from Camelina sativa seed treated by dielectric-barrier discharge cold plasma

This study aimed to investigate the effects of dielectric-barrier discharge (DBD) cold plasma (CP) pretreatment on Camelina sativa “Soheil cultivar” seed. A DBD plasma reactor system was employed for this purpose. The experiments were performed by taking into account variables including voltages of 15, 18, and 21 kV and times of 2, 4, 8, and 16 min. The measured properties were oil yield extraction (%), oil colour parameters (CIEL*a*b*), protein content (meal) (%), surface analysis using Scanning Electron Microscopy (SEM), and fatty acids profile of Camelina sativa. The results revealed that the CP treatment had a significant improvement in different properties of the extracted oil. It was observed that the extracted oil was increased, with the increasing time of CP exposure. The treatments of CP enhanced the oil yield from 24.3 to 31.5%, and the optimal conditions were identified as 21 kV and 16 min. Also, the maximum protein amount was observed for the samples treated by CP (39.5%). The SEM analysis showed that the cell structures of pre-treated Camelina samples were damaged, thereby improved the oil extraction efficiency. The variations in the values of L*, a*, and b* (max-min) were calculated to be 3.9, −2.5, and 9.7, respectively, which indicated minor changes of CP treatment on the oil colour parameters. The treated samples showed considerable changes of enhancement in linolenic and linoleic acids among poly-unsaturated fatty acids; and a reduction in palmitic acid content, among saturated fatty acids.     

Strict inductive limits in locally convex cones

We propose a definition for strict inductive limits in locally convex cones. By this definition, we prove that the strict inductive limit of a sequence of locally convex cones with the strict separation property has the same strict separation property. Also we establish that the strict inductive limit of a sequences of separated cones is separated too. Finally we verify barreledness for this strict inductive limit.     

Influence of the third monomer on lauryl methacrylate–methyl methacrylate emulsion terpolymerization

An experimental study shows how the emulsion terpolymerization of lauryl methacrylate (LMA) and methyl methacrylate is influenced by the nature of the third monomer. The third monomer is either glycidyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, or styrene. We report the synthesis of terpolymer particles with an appreciably high content of the very hydrophobic LMA (between 0.2515 and 0.238 molar fraction in the monomer mixture) in 60:40 weight water/ethanol mixture as the continuous phase, poly(vinyl pyrrolidone) as a polymeric steric stabilizer, and potassium peroxodisulfate as the initiator. The emulsion terpolymerization proceeds smoothly without the formation of coagulum and leads to particles with an average diameter clearly below 1 μm. We discuss the overall polymerization behavior regarding conversion–time curves, particle morphology, and glass transition temperature of the terpolymers in dependence of the lyophilicity/lyophobicity of the monomer mixture.     

Flow injection on-line determination of uranium after preconcentration on XAD-4 resin impregnated with dibenzoylmethane

A flow injection on-line determination of uranium(VI) after preconcentration in a minicolumn having amberlite XAD-4 resin impregnated with dibenzoylmethane (DBM) is described. Uranium(VI) is selectively adsorbed from aqueous solution of pH 5.5 in the minicolumn (5.5 cm long with 5.0 mm i.d.) at a flow rate of 13.6 mL min⁻¹. The uranium(VI) complex was desorbed from the resin by 0.1 mol dm⁻³ HCl at a flow rate of 4.2 mL min⁻¹ and mixed with arsenazo-III solution (0.05% solution in 0.1 mol dm⁻³ HCl, 4.2 mL min⁻¹), and taken to the flow through cell of spectrophotometer where its absorbance was measured at 651 nm. Various parameters affecting the complex formation and its elution were optimized. Peak height (absorbance) was used for data analyses. The preconcentration factors of 36 and 143, detection limits of 0.9 and 0.232 μg L⁻¹, sample throughputs of 40 and 10 were obtained for preconcentration time of 60 and 300 s, respectively. The tolerance limits of many interfering cations like Th(IV) and rare-earth elements were improved. The proposed method was applied on different water (spiked tap, well and sea water) and biological samples and good recovery was obtained. The method was also validated on mocked uranium ore sample and the results were in good agreement with the reported value.