On pairs of commuting nilpotent matrices

Let B be a nilpotent matrix and suppose that its Jordan canonical form is determined by a partition λ. Then it is known that its nilpotent commutator is an irreducible variety and that there is a unique partition μ such that the intersection of the orbit of nilpotent matrices corresponding to μ with is dense in . We prove that map given by is an idempotent map. This answers a question of Basili and Iarrobino [9] and gives a partial answer to a question of Panyushev [18]. In the proof, we use the fact that for a generic matrix the algebra generated by A and B is a Gorenstein algebra. Thus, a generic pair of commuting nilpotent matrices generates a Gorenstein algebra. We also describe in terms of λ if has at most two parts.     

Efficiency and characteristics of solid-phase (ion-exchange) extraction for removal of Cl- matrix

Certain types of samples contain chloride in concentrations that are too high to accurately determine other anions by ion chromatography without any pretreatment. One of the most widely used approaches for such samples is matrix elimination using disposable cartridges containing a cation-exchange resin in the Ag+ form. The efficiency and characteristics of the commercially available cartridge for Cl- removal were tested by the on-line connection of the cartridge effluent to an inductively coupled plasma mass spectrometer. Displacement efficiency of Ag+ ions and loading capacity of the cartridges were studied at different flow-rates. Significant amounts of silver were detected in the effluent, which were attributed to colloidal AgCl as well as dissolved Ag+ ions. Because silver ions can cause irreversible damage to the analytical column, an Ag cartridge followed by an on line filter (pore size 0.22 microm) and cartridge in the H3O+ form were proposed for improvement of this sample pretreatment technique for chloride removal.     

Steroid extraction in a microchannel system--mathematical modelling and experiments

The continuous ethyl acetate extraction of progesterone and 11alpha-hydroxyprogesterone, a reactant and the product of the biotransformation step involved in corticosteroid production, was studied in a microchannel at different flow velocities. In addition, non-steady state batch extraction without mixing was performed and modelled in order to verify the theoretically predicted parameters. In order to analyze experimental data and to forecast microreactor performance, a three-dimensional mathematical model with convection and diffusion terms was developed considering the velocity profile for laminar flow of two parallel phases in a microchannel at steady-state conditions. For the numerical solution of a complex equation system, non-equidistant finite differences were used. Very good agreement between model calculations and experimental data was achieved without any fitting procedure. Due to the efficient phase separation and high extraction yields obtained, the micro scale extraction units were found to be a promising tool for the development of an integrated system of 11alpha-hydroxylation of progesterone by Rhizopus nigricans in the form of pellets.     

Optimization of Laccase Production by <Emphasis Type="Italic">Trametes versicolor</Emphasis> Cultivated on Industrial Waste

Laccases are very interesting biocatalysts for several industrial applications. Its production by different white-rot fungi can be stimulated by a variety of inducing substrates, and the use of lignocellulosic wastes or industrial by-products is one of the possible approaches to reduce production costs. In this work, various industrial wastes were tested for laccase production by Trametes versicolor MZKI G-99. Solid waste from chemomechanical treatment facility of a paper manufacturing plant showed the highest potential for laccase production. Enzyme production during submerged cultivation of T. versicolor on the chosen industrial waste has been further improved by medium optimization using genetic algorithm. Concentrations of five components in the medium were optimized within 60 shake-flasks experiments, where the highest laccase activity of 2,378 U dm⁻³ was achieved. Waste from the paper industry containing microparticles of CaCO₃ was found to stimulate the formation of freely dispersed mycelium and laccase production during submerged cultivation of T. versicolor. It was proven to be a safe and inexpensive substrate for commercial production of laccase and might be more widely applicable for metabolite production by filamentous fungi.     

Au nanoparticle-functionalised WO3 nanoneedles and their application in high sensitivity gas sensor devices

A new method of synthesising nanoparticle-functionalised nanostructured materials via Aerosol Assisted Chemical Vapour Deposition (AACVD) has been developed. Co-deposition of Au nanoparticles with WO(3) nanoneedles has been used to deposit a sensing layer directly onto gas sensor substrates providing devices with a six-fold increase in response to low concentrations of a test analyte (ethanol).