Application of polypyrrole nanowires for the development of a tyrosinase biosensor

Polypyrrole nanowires (PPyNWs) were fabricated and examined as a structural component of amperometric biosensor matrix. An enzyme, tyrosinase (TYR), was immobilized onto PPyNWs using glutaraldehyde (GA). Matrix composite morphology was investigated using scanning electron microscopy. Electrochemical behavior of the prepared PPyNWs/GA/TYR biosensor towards catechol was studied and the assessment of its analytical characteristics was carried out taking into account linear range, sensitivity, repeatability, reproducibility and operational stability.     

Evaluation of S-Entropy Production in a Single-Membrane System in Concentration Polarization Conditions

Transport in Porous Media - S-entropy source of membrane system was described based on linear non-equilibrium thermodynamics. The volume and diffusive fluxes of non-electrolyte solutions and...     

Maass relations for Saito–Kurokawa lifts of higher levels

The Ramanujan Journal - It is known that among Siegel modular forms of degree 2 and level 1 the only functions that violate the Ramanujan conjecture are Saito–Kurokawa lifts of modular forms...     

On the cross-effects of coupled macroscopic transport equations in porous media

In this paper, the derivation of macroscopic transport equations for this cases of simultaneous heat and water, chemical and water or electrical and water fluxes in porous media is presented. Based on themicro-macro passage using the method of homogenization of periodic structures, it is shown that the resulting macroscopic equations reveal zero-valued cross-coupling effects for the case of heat and water transport as well as chemical and water transport. In the case of electrical and water transport, a nonsymmetrical coupling was found.Notations b mobility - c concentration of a chemical - D rate of deformation tensor - D molecular diffusion coefficient - D _ij ^eff macroscopic (or effective) diffusion tensor - electric field - E ₀ initial electric field - k _ij molecular tensor - j, j ^*, current densities - K _ij macroscopic permeability tensor - l characteristic length of the ERV or the periodic cell - L characteristic macroscopic length - L _ijkl coupled flows coefficients - n _i unit outward vector normal to - p pressure - q _t ,q _t ⁺ , heat fluxes - q _c ,q _c ⁺ , chemical fluxes - s specific entropy or the entropy density - S entropy per unit volume - t time variable - t _ij local tensor - T absolute temperature - v _i velocity - V ₀ initial electric potential - V electric potential - x macroscopic (or slow) space variable - y microscopic (or fast) space variable - _i local vectorial field - _i local vectorial field - electric charge density on the solid surface - , bulk and shear viscosities of the fluid - _ij local tensor - _ij local tensor - _i local vector - _ij molecular conductivity tensor - _ij ^eff effective conductivity tensor - homogenization parameter - fluid density - ₀ ion-conductivity of fluid - _ij dielectric tensor - _i ¹ , _i ² , _i ³ local vectors - ⁴ local scalar - _S solid volume in the periodic cell - _L volume of pores in the periodic cell - boundary between _S and _L - ^s rate of entropy production per unit volume - total volume of the periodic cell - _l volume of pores in the cell On leave from the Politechnika Gdanska; ul. Majakowskiego 11/12, 80-952, Gdask, Poland.     

Application of Raman Spectroscopy for Differentiation Among Cotton and Viscose Fibers Dyed with Several Dye Classes

The difference between natural and regenerated cellulose fibers caused by variations in the degree of polymerization and supramolecular structure, influences dyes adsorption properties. The aim of the study was to discriminate between cotton and viscose fibers, dyed with several dye classes, using Raman spectroscopy. 8 reactive and 6 direct dyes were used for colouring textiles under laboratory conditions. Spectra of fibers were obtained with the use of three excitation sources: 514, 633, and 785 nm. The obtained results allowed for the differentiation of studied types of cellulose fibers, dyed with the same dye, at the same or very similar concentrations.     

Use of a Dynamic Light Scattering Technique for SDS/Water/Pentanol Studies

The interpretation of micelle/aggregate size obtained by use of the DLS technique for SDS/water/pentanol systems was discussed by comparison of the results of measurement with theoretical data. For most of the studied systems, the apparent radii (R _h,app ) did not satisfactorily characterize the size of the aggregates (R _h,app  < 1 nm). The use of a correction factor (f = 0.26) confirmed that the discrepancies were associated with the electrostatic intermicellar interactions. However, the fuzzy optical interface between dispersed and dispersing phases can also be the reason of such results. An increase of pentanol content caused a decrease of the droplet radius in w/o systems but in o/w systems the changes were negligible.     

Chromogenic azole diazothiacrown ethers

Azocrown ethers with sulphur atoms and pyrrole or imidazole residue as a part of macrocycle have been synthesised. Their metal complexation abilities in acetonitrile were studied using UV–vis spectrophotometry. The largest spectral changes were observed for both pyrrole- and imidazole-azothiacrown ethers on complexation with Pb^2 + , Cu^2 + , Zn^2 + , Ni^2 + , Co^2 +  and Ag⁺ ions. In the case of alkali and alkaline earth metal ions no spectral changes were found. Preliminary studies of ion-selective membrane electrodes with synthesised ionophores are presented. In the measurement for transition/heavy metal cations, only copper and lead give high responses. X-ray structure of 18-membered pyrrole azothiacrown ether is described.     

Usefulness of the chaotropic effect in sample preparation for chromatographic analysis of acidic xenobiotics in human plasma

In this study a new RP‐HPLC with photo‐diode array detection method for the determination of ibuprofen ((RS)‐2‐(4‐isobutylphenyl)propionic acid) in human plasma samples was developed. Samples were prepared by SPE and analyzed by an isocratic elution mode over a C₁₈ column using 80% methanol. A novel sample pretreatment method, based on the addition of ionic liquids possessing chaotropic ions to small human plasma sample (100 μL), was elaborated. 1‐Butyl‐3‐methylimidazolium chloride and 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIM BF₄) were tested from the point of view of extraction yield. Quantification was based on calibration curve applying diclofenac as the internal standard. Owing to dilution of plasma sample by 2 mM aqueous solution of BMIM BF₄ before SPE, appropriate sample purification and extraction yields higher than 95% with precision lower than 2% can be achieved. Linear coefficients of correlation (r²) were >0.99 in the range of 0.3–5 μg/mL ibuprofen concentration in plasma. The limit of quantification was 65 ng/mL and the detection limit for ibuprofen was 19.5 ng/mL.