Ink‐Jet Microdispensing for the Formation of Gradients of Immobilised Enzyme Activity

Summary: The integration of gradients of enzyme activity in microstructured biosensor arrays enables intrinsic on‐line quality control of biosensor performance. Multiple sensor elements with different compositions and hence varying responses for the same analyte are evaluated as a basis for improving data reliability. The formation of glucose oxidase/polymer microstructures using a piezo microdispenser and their examination by scanning electrochemical microscopy (SECM) are used to demonstrate the feasibility of this approach.

Optical microscope image of grids obtained by dispensing of 1 mg/mL GOx and 2 mg/mL Vinnapas® mixture.     

Existence and asymptotic behaviour for a discrete hyperbolic system

In a real Hilbert space, we investigate the existence, uniqueness and asymptotic behaviour of the strong and weak solutions to a nonlinear infinite hyperbolic system subject to a boundary condition and initial data.     

Non-isothermal kinetics in mixtures of barium carbonate and titanium dioxide (anatase)

The complexes AgL (L = theobromine, 1,3,8-trimethylxanthine and 3,8-dimethylxanthine) Hg₂L·NO₃ (L = 3,8-dimethylxanthine and 1,3,8-trimethylxanthine) and Hg₂C₂(NO₃)₂ (C = caffeine), were prepared in aqueous and HNO₃ medium. These complexes were characterized by IR, ¹H-NMR, TG, DTG and DSC techniques.     

Improved enzyme retention from an electropolymerized polypyrrole-alginate matrix in the development of biosensors

A novel pyrrole-alginate was synthesized providing a gel by Ca²⁺ cross-linking. The subsequent in situ electrochemical polymerization of the linked pyrrole groups at 0.93 V led to the formation of a composite polypyrrole–gel matrix exhibiting a greater enzyme retention as well as increased alginate stability towards the destructive effect of phosphate anions unlike the natural alginate gel. The presence of the electropolymerized chains was clearly indicated by the decrease of the permeability when compared to natural alginate gel, namely 2.7 × 10⁻² and 3.65 × 10⁻¹ cm s⁻¹ respectively, using as an electroactive permeate, hydroquinone. Moreover, the analytical performance of glucose oxidase-based composite alginate for the determination of glucose was determined.     

Thermal behavior of some N,N-dimethylbiguanide derivatives displaying antimicrobial activity

N,N-Dimethylbiguanide derivatives (HDMBG)X, where X=CH₃COO (1), Cl (2) and NO₃ (3) respectively, exhibit in vitro antimicrobial activity on representative bacterial and fungal strains. The presence of N,N-dimethylbiguanidium ion for all derivatives was evidenced by IR and ¹H NMR spectra. Thermal analysis gave information on their decomposition steps and also on the accompanying thermodynamic effects. According to TG and DTG curves processes as melting, oxidative degradation as well as oxidative condensation of –C=N– units occur. The different nature of the anions results different melting points. Paracyanide formation at various condensation degrees was observed.     

Synthesis,thermal, spectral,antimicrobial and cytotoxicity profile of the Schiff bases bearing pyrazolone moiety and their Cu(II) complexes

Journal of Thermal Analysis and Calorimetry - A series of Schiff bases resulted in the [1?+?1] condensation of 8-alkyl-2-hydroxy-tricyclo[7.3.1.02.7]-tridecan-13-one with the...     

Quasistatic Crack Growth in Elasto-Plastic Materials: The Two-Dimensional Case

We study a variational model for the quasistatic evolution of elasto-plastic materials with cracks in the case of planar small strain associative elasto-plasticity.