Alkyl Xylosides: Physico‐Chemical Properties and Influence on Environmental Bacteria Cells

A group of four selected non‐ionic surfactants based on carbohydrates, namely octyl d ‐xyloside (C₈X), nonyl d ‐xyloside (C₉X), decyl d ‐xyloside (C₁₀X) and dodecyl d ‐xyloside (C₁₂X), have been investigated to accomplish a better understanding of their physico‐chemical properties as well as biological activities. The surface‐active properties, such as critical micelle concentration (CMC), emulsion and foam stability, the impact of the compounds on cell surface hydrophobicity and cell membrane permeability together with their toxicity on the selected bacterial strains have been determined as well. The studied group of surfactants showed high surface‐active properties allowing a decrease in the surface tension to values below 25 mN m^?1 for dodecyl d ‐xyloside at the CMC. The investigated compounds did not have any toxic influence on two Pseudomonas bacterial strains at concentrations below 25 mg L^?1. The studied long‐chain alkyl xylosides influenced both the cell inner membrane permeability and the cell surface hydrophobicity. Furthermore, the alkyl chain length, as well as the surfactant concentration, had a significant impact on the modifications of the cell surface properties. The tested non‐ionic surfactants exhibited strong surface‐active properties accompanied by the significant influence on growth and properties of Pseudomonas bacteria cells.     

Dressing process in the grinding of aerospace blade root

Journal of Mechanical Science and Technology - This study investigates the grinding wheel dressing process in the grinding of aerospace blade root fir tree profile made from Inconel 718 alloy. This...     

Electrical model of the alkaline electrolyser dedicated for SPICE

In this paper, properties of the alkaline electrolyser fed from the voltage source, producing the rectangular pulse train, were investigated. A model of this electrolyser for SPICE in the form of an electrical network was proposed. The structure of this electrical model was described, and the values of parameters of the model were presented. The correctness of this model was verified experimentally in a wide range of frequency. Using the worked out model, several characteristics of the electrolyser were calculated, and the influence of amplitude, frequency, and the duty factor of the supplying voltage on productivity and watt‐hour efficiency of the electrolysis process was discussed. The investigations were performed for 2 different concentration values of the KOH solution.     

Symbolic analysis of electric networks with higher order summative cofactors and parameter decision diagrams

The paper introduces the concept of higher order summative cofactors (HOSCs) to the circuit analysis. Although the concept is not new, it is not well known. In the paper, some mathematical background of HOSCs is presented. The further development of the concept of HOSC will yield computer implementation arithmetic of HOSC. A cancellation‐free symbolic analysis technique, which is based on HOSC arithmetic, is presented. This technique allows results to be created directly from a netlist in the form of a binary decision diagram, which is called a parameter decision diagram. Additionally, HOSC arithmetic allows the calculation to be started in many places (sometimes distant) simultaneously. The techniques of rolling up the already analyzed parts of a circuit, which is built into HOSC arithmetic, result in a novel multilevel hierarchical analysis method that is called hierarchical parameter decision diagram (HPDD). Unlike in most hierarchical methods, the results that are obtained based on the subcircuit representation in HPDD always maintain a cancellation‐free form. The HPDD always represents the sum of the product form, which is heavily compressed due to the self‐similarities of the actual circuit. The time that is required for any recalculation of the transfer functions is greatly reduced. Analysis of models that are based on pathological components is also a natural consequence of using HOSC arithmetic.     

Electrochemical corrosion resistance of Fe-Nd-B permanent magnets

The corrosion behaviour of three permanent magnets based on the Fe-R-B system, namely Fe_76.9Nd_15.1 B₈ (Vacodym 335), Fe_76.7Nd_14.3DyB₈ (Vacodym 370) and Fe₇₇Nd₁₅B₈ (Neomax 35) was investigated in 0.5 M H₂SO₄ using mass loss and electrochemical techniques. Differences in the chemical composition of the tested magnets did not affect the runs of polarization curves in the active dissolution range or in the cathodic one, but they influenced the runs of these curves in the passive state. The magnets show distinct lack of resistance to acid corrosion both in the magnetized and demagnetized state. Weak corrosion resistance appears also at strongly cathodic polarizations, and the rate of this abnormal dissolution increases with the rise of the hydrogen evolution rate on the surface of the magnets     

Low-Pressure Carbonylation of Benzyl Bromide with Palladium Complexes Modified with PNS (PNS = Ph2PCH2CH2C(O)NHC(CH3)2CH2SO3Li) or P(OPh)3. Structural Identification of Palladium-Catalyst Intermediate

The catalytic activities of two palladium complexes with water soluble phosphine PNS (PNS = Ph₂PCH₂CH₂C(O)NHC(CH₃)₂CH₂SO₃Li) (I) and phosphite P(OPh)₃ (II) were tested in the carbonylation of benzyl bromide in methanol at 40–50°C and 1 atm of CO. The first catalyst, (I), was formed in situ from PdCl₂(cod) and PNS, the second one, (II), was based on the PdCl₂(P(OPh)₃)₂ complex. At the ratio of [NEt₃]:[PhCH₂Br] equal to 2.5 the yields of phenylacetic acid methyl ester were 83–86% in the carbonylation with PNS and 100% in the carbonylation with P(OPh)₃. The palladium catalyst with P(OPh)₃ produced under the same conditions 70% of phenylacetic acid methyl ester in the carbonylation of benzyl chloride and 60% of 2-methylphenylacetic acid methyl ester in the carbonylation of 1-bromoethylbenzene. The lower rate of carbonylation of 1-bromoethylbenzyl bromide in comparison to that of benzyl bromide was explained by the lower rate of the substrate oxidative addition step leading to palladium benzyl complexes. Two palladium benzyl complexes, cis-PdBr(PhCH₂)(P(OPh)₃)₂ and trans-PdBr(PhCH(Me))(P(OPh)₃)₂ have been isolated and characterized (X-ray, ³¹P and ¹H NMR).     

Kinetics and mechanism of the magnesium electrode reaction in molten magnesium chloride

Using electrochemical impedance spectroscopy (EIS) and relaxation method with galvanostatic perturbation (RM) the kinetics and mechanism of the magnesium electrode reaction in pure molten M9Cl₂ have been determined at several temperatures. A three-step electrode process has been found, the high frequency process being pure charge transfer with the low frequency process showing mixed charge transfer-diffusion character. The low frequency step has also been treated as a preceding chemical reaction followed by charge transfer. On the basis of the corresponding exchange current densities and Warburg diffusion impedance, a mechanism of the overall electrode reaction in this melt is proposed.     

The dyes possessing diazine residue as effective photoinitiators of free radicals polymerization

Summary The series of the dyes possessing diazine residue have been investigated as visible-light absorbing photoinitiators of free radical polymerization. The rates of photoinitiation depend on the structure of the dye. Mechanism of the photoinitiation involves the electron transfer process between the dye and the electron donor (co-initiator). The dyes possessing diazine residue in the presence of a suitable electron donor are very effective photoinitiators. This can be attributed to the high quantum yield of their triplet state formation and high rate constant of electron transfer reaction between the dye and electron donor.     

Recovery of uranium and other valuable metals from substrates and waste from copper and phosphate industries

ABSTRACT

Recovery of heavy metals and other useful materials from industrial waste is crucial because it reduces the environmental impact of the production facilities. The selective separation of uranium from such waste might be very important in the context of future energy production and the still essential role of nuclear power in the energy mix. The copper ores, waste from the copper industry, phosphate rocks and phosphogypsum were considered as sources of uranium in these studies. Apart from uranium, these materials also contain other valuable metals, e.g. rare earth elements. In the present work the procedures of extraction of uranium and accompanying metals designed for specific materials – the potential sources of metals, were reported.