Robust stabilization of a chemical reactor

Robust static output feedback control was applied to a continuous stirred tank reactor with parametric uncertainty and multiple steady states in which exothermic reaction takes place. The problem of robust controller design was converted to a solution of linear matrix inequalities and a computationally simple non-iterative algorithm is presented. The possibility of using robust static output feedback for stabilization of reactors with uncertainty and comparison of robust P and PI controllers with an optimal controller is demonstrated by simulation results.     

Peroxide-based route assisted with inverse microemulsion process to well-dispersed Bi<Subscript>4</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> nanocrystals

Well-dispersed bismuth titanate (BIT) nanocrystals with an average size ranged from 3 to 60 nm were synthesized via a peroxide-based route assisted with an inverse microemulsion process. The crystallite size and lattice parameter of BIT upon variable-temperature were determined by X-ray diffraction (XRD). The particle size was confirmed by transmission electron microscopy (TEM). Thermal decomposition behaviour of Ti-peroxy and BIT gel and crystallization kinetics of BIT nanocrystals were investigated by differential scanning calorimetry/thermogravimetry (DSC/TG) and Fourier-Transform infrared spectroscopy (FTIR). Analysis of nonisothermal DSC data yielded a value of 220.84 ± 2.73 KJ/mol and 2.25 ± 0.26 for the activation energy of crystallization (E _a) and the Avrami exponent (n), respectively.     

Disposable Biosensor Based on Amidase/CeO2/GNR Modified Inkjet‐printed CNT Electrodes‐droplet Based Paracetamol Detection in Biological Fluids for “Point‐of‐care” Applications

A disposable acetaminophen biosensor based on inkjet‐printed CNT electrodes (IJPCNT) modified with amidase/cerium dioxide@graphene nanoribbons composite was developed (ACeO2@GNR/IJPCNT). The enzyme amidase A was used for the first time as a recognition element. Inkjet‐printed CNT electrodes served as a basis for the construction of a biosensor that enables droplet detection using 5 μL sample volume. The biosensor showed high selectivity, sensitivity, a low detection limit of 0.18 μM and a wide working linear range from 1 to 100 μM. The proposed approach allows fast and reliable detection of acetaminophen in biological fluids with negligible matrix effect and remarkable reproducibility.     

Interference of white light in tandem configuration of birefringent crystal and sensing birefringent fiber

Spectral interference of white-light beams propagating through a tandem configuration of birefringent crystal and sensing birefringent fiber is analyzed theoretically and experimentally. The spectral interference law is expressed analytically under the condition of a Gaussian response function of a spectrometer taking into account the dispersion of birefringence in the crystal and in the fiber. Two types of spectral interferograms are modeled knowing dispersion characteristics of the sensing fiber and using a quartz crystal of the positive or a calcite crystal of the negative birefringence. The theoretical analysis is accompanied by two experiments employing a highly birefringent fiber and a birefringent quartz crystal of two suitable thicknesses. Within both experiments the spectral interference fringes are resolved in accordance with the theory with phases dependent on the fiber length.     

Photoelectrochemical properties of TiO x layers prepared by DC pulsed unbalanced reactive magnetron sputtering

Three sets of titanium oxide layers with different oxygen content were prepared by DC pulsed reactive magnetron sputtering. The layers were characterised by their thickness, conductivity, refractive index, band-gap and flat band potential. The photoelectric and photocatalytic activities of the layers irradiated by Xe discharge lamp were tested in NaOH and phenol water solution, respectively. Rather high activity of prepared layers was found; no expressive activity increase was, however, observed in contrary to the expectation connected with suboxide forms of TiO _x .     

Decompositions of complete bipartite and tripartite graphs into selfcomplementary factors with finite diameters

We completely determine the spectrum of the complete bipartite and tripartite graphs that are decomposable into two isomorphic factors with a finite diameter.1991 Mathematics Subject Classification. 05C70     

Multiple sample amplification and genotyping integrated on a single electronic microarray

We report a novel method that allows simultaneous in situ amplification and then genotyping of single nucleotide polymorphism (SNP) for multiple samples on a single electronic microarray. The locus coding for one of the common inherited thrombosis risk factors, Factor V Leiden (FVL), was chosen as a model system for SNP analysis. This method combines strand displacement amplification (SDA) with electrophoretic movement and concentration of DNA on electronic microarrays to provide a single platform for DNA amplification and analysis. The method includes: electronic anchoring of allele-specific SDA amplifiable primers (APs) and a nonamplifiable primer (NAP) to different electrodes, electronic hybridization of genomic DNA from different samples to those primers, in situ amplification of target DNA, and genotyping of FVL. Compared to previous anchored SDA methods, the addition of a NAP improves detection signals by at least 20-fold. The sensitivity of this method is dependent on the amplification time. Using this method, nine different genomic DNA samples with known FVL genotypes were amplified and correctly genotyped on a single electronic microarray without any contamination between samples. The present method could streamline development of nucleic acid-based assays in applications of molecular diagnostic, point-of-care testing, and forensic detection, which often require the capability to analyze multiple samples efficiently.     

New tools for molecular imaging of redox metabolism: development of a fluorogenic probe for 3 alpha-hydroxysteroid dehydrogenases

A new fluorogenic substrate was developed for 3alpha-hydroxysteroid dehydrogenases (3alpha-HSD), including the human enzymes implicated in important physiological functions (androgen deactivation, neurosteroid activation). While ketone 5 is nonfluorescent, the corresponding alcohol exhibits high fluorescence with emission maximum at 510 nm, thus constituting a redox optical switch. This study began with a chemical concept of a ketone-alcohol optical switch which guided the synthesis of a focused array of compounds. Subsequently, seven compounds were selected (1-7) on the basis of their optical and chemical (stability) properties and were submitted to a screen against a panel of dehydrogenase enzymes. Probe 5 was found to be highly selective for bacterial, rat, and human 3alpha-HSD enzymes. The kinetic parameters were obtained for human 3alpha-HSD enzyme (type 2 isozyme, AKR 1C3; Km = 2.5 muM, kcat = 8.2 min-1). Remarkably, comparison to 5alpha-dihydrotestosterone (5alpha-DHT, Km = 26 muM, kcat = 0.25 min-1, Figure 4), a likely physiological substrate in prostate, revealed that synthetic probe 5 is in fact a far better substrate for this enzyme. Structure 5 represents an exciting lead for the development of a redox imaging probe.