Reliable gain‐scheduled control design for networked control systems

In this article, the problem of reliable gain‐scheduled H_∞ performance optimization and controller design for a class of discrete‐time networked control system (NCS) is discussed. The main aim of this work is to design a gain‐scheduled controller, which consists of not only the constant parameters but also the time‐varying parameter such that NCS is asymptotically stable. In particular, the proposed gain‐scheduled controller is not only based on fixed gains but also the measured time‐varying parameter. Further, the result is extended to obtain a robust reliable gain‐scheduled H_∞ control by considering both unknown disturbances and linear fractional transformation parametric uncertainties in the system model. By constructing a parameter‐dependent Lyapunov–Krasovskii functional, a new set of sufficient conditions are obtained in terms of linear matrix inequalities (LMIs). The existence conditions for controllers are formulated in the form of LMIs, and the controller design is cast into a convex optimization problem subject to LMI constraints. Finally, a numerical example based on a station‐keeping satellite system is given to demonstrate the effectiveness and applicability of the proposed reliable control law. © 2014 Wiley Periodicals, Inc. Complexity 21: 214–228, 2015     

The effect of fluorine-substituted acrylate monomers on the electro-optical and morphological properties of polymer dispersed liquid crystals

The effects of fluorinated acrylate monomers on the electro-optical and morphological properties of polymer dispersed liquid crystal (PDLC) films are reported. The partial fluorination of host polymer matrices resulted in improved optical properties and better defined morphologies. An enhancement in contrast ratio was observed for fluorinated systems containing trifluoroethyl acrylate (TFEA) and hexafluoroisopropyl acrylate (HFIPA). Conversely, the incorporation of methyl acrylate (MA), a chemically similar non-fluorinated acrylate, resulted in no appreciable change in contrast ratio and an increase in relaxation time. Scanning electron microscopy morphological studies were conducted to understand further the influence of fluorinated monomers in PDLC systems.     

Ammonium uranyl carbonate (AUC) based process of simultaneous partitioning and reconversion for uranium and plutonium in fast breeder reactors (FBRs) fuel reprocessing

Ammonium uranyl carbonate (AUC) based process of simultaneous partitioning and reconversion for uranium and plutonium is developed for the recovery of uranium and plutonium present in spent fuel of fast breeder reactors (FBRs). Effect of pH on the solubility of carbonates of uranium and plutonium in ammonium carbonate medium is studied. Effect of mole ratios of uranium and plutonium as a function of uranium and plutonium concentration at pH 8.0–8.5 for effective separation of uranium and plutonium to each other is studied. Feasibility of reconversion of plutonium in carbonate medium is also studied. The studies indicate that uranium is selectively precipitated as AUC at pH 8.0–8.5 by adding ammonium carbonate solution leaving plutonium in the filtrate. Plutonium in the filtrate after acidified with concentrated nitric acid could also be precipitated as carbonate at pH 6.5–7.0 by adding ammonium carbonate solution. A flow sheet is proposed and evaluated for partitioning and reconversion of uranium and plutonium simultaneously in the FBR fuel reprocessing.     

Three-Component Synthesis and 1,3-Dipolar Cycloaddition of Highly Functionalized Pyrans with Nitrile Oxides: Easy Access to 1,2,4-Oxadiazoles

Three-component reaction of 1-[(4-chlorophenyl)sulfanyl]acetone, malononitrile, and substituted aromatic aldehydes in the presence of sodium ethoxide under simple mixing at ambient temperature for 5–8 min afforded highly functionalized 4H-pyrans in good to excellent yields. 1,3-Dipolar cycloaddition of nitrile oxides over the nitrile functionality of the 4H-pyrans furnished 1,2,4-oxadiazoles in moderate yields.

Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for full experimental and spectral details.     

Thermal decomposition of reversed TALSPEAK solvent

Reversed TALSPEAK (RT) Solvent [0.3 M di-(2-ethyl hexyl) phosphoric acid or D2EPHA in 0.2 M TBP in normal paraffinic diluent] is used as extractant in partitioning of lanthanides and actinides in post-UREX process flow sheets. There is no experimental data available in literature describing pressurization either due to the thermal decomposition or the reaction of RT solvent with nitric acid at elevated temperatures. Experiments were conducted for heating of RT solvent and acid equilibrated RT solvent under closed-vent adiabatic conditions. During these experiments, considerable pressurization was observed. In this paper, results of these experiments are discussed in detail.     

Macrocycle breathing in [2]rotaxanes with tetralactam macrocycles

The structural dynamics of two pairs of [2]rotaxanes were compared using variable-temperature NMR. Each rotaxane had a surrounding tetralactam macrocycle with either 2,6-pyridine dicarboxamide or isophthalamide bridging units. Differences were observed in two types of rotational processes: spinning of the phenylene wall units in the surrounding macrocycle of squaraine rotaxanes and macrocycle pirouetting in xanthone rotaxanes. The rotaxanes with macrocycles containing 2,6-pyridine dicarboxamide bridges exhibited higher rotational barriers due to a cavity contraction effect, which disfavored macrocycle breathing.     

Copper/H2O2-mediated oxidation of 2'-deoxyguanosine in the presence of 2-naphthol leads to the formation of two distinct isomeric adducts

Exposure of cells to phenolic compounds through exogenous and endogenous sources can lead to deleterious effects via nucleobase modifications of DNA occurring under oxidative conditions. 2'-Deoxyguanosine (dG) is the most electron rich of the four canonical bases and includes many nucleophilic sites; it is also susceptible to oxidation with numerous reactive oxygen species. In these studies, dG was allowed to react with 2-naphthol in the presence of copper or iron salts yielding two principal isomeric products. Spectroscopic analysis and reactions with alkylated nucleosides support the assignment of compound 1a/1b as a pair of atropisomer N(2) adducts and compound 2a/2b as a diastereomeric mixture of tricyclic [4.3.3.0] adducts. Both products are the result of an overall four-electron oxidation process and consequently have the same masses, though drastically different structures, providing mechanistic insight into their formation. Thus, dG alkylation by 2-naphthol under oxidative conditions yields products whose structural properties are altered, leading to potentially mutagenic effects in genomic DNA.     

Effect of N(4)-phenyl substitution in 2-oxo-1,2-dihydroquinoline-3-carbaldehyde semicarbazones on the structure, DNA/protein interaction, and antioxidative and cytotoxic activity of Cu(II) complexes

A new ligand, 2-oxo-1,2-dihydroquinoline-3-carbaldehyde semicarbazone (OQsc-H) (1);, its N(4)-phenyl derivative (OQsc-Ph) (2); and their corresponding copper(II) complexes [CuCl(2)(OQsc-H)]·H(2)O·CH(3)OH (3), [CuCl(2)(OQsc-Ph)(H(2)O)]·CH(3)OH (4), and [CuNO(3)(OQsc-Ph)(H(2)O)]NO(3)·H(2)O·C(2)H(5)OH (5) have been synthesized and characterized by structural, analytical, and spectral methods, in order to investigate the influence of N(4)-phenyl substitution on structure and pharmacological properties. In all of the complexes, the ligands coordinated to the Cu(II) ion in a neutral fashion via ONO donor atoms. The single-crystal X-ray structures of neutral complex (3) and cationic complex (5) exhibit a slightly distorted square-pyramidal structure, while neutral complex (4) revealed an octahedral structure. The interaction of the compounds with calf thymus DNA (CT-DNA) has been explored by absorption and emission titration methods, which revealed that compounds 1-5 could interact with CT-DNA through intercalation. A gel electrophoresis pictogram demonstrated the ability of the complexes (3-5) to cleave the pBR322 plasmid DNA through a hydrolytic process. The interactions of the compounds with bovine serum albumin (BSA) were also investigated using UV-visible, fluorescence, and synchronous fluorescence spectroscopic methods. The results indicated that all of the compounds could quench the intrinsic fluorescence of BSA in a static quenching process. Investigations of antioxidative properties showed that all of the compounds have strong radical scavenging potencies against hydroxyl radicals, 2,2-diphenyl-1-picrylhydrazyl radicals, nitric oxide, and superoxide anion radicals. Further, the cytotoxic effect of the compounds examined on cancerous cell lines such as human cervical cancer cells (HeLa), human laryngeal epithelial carcinoma cells (HEp-2), human liver carcinoma cells (Hep G2), human skin cancer cells (A431), and noncancerous NIH 3T3 mouse embryonic fibroblasts cell lines showed that all three complexes exhibited substantial cytotoxic activity. Further, all of the pharmacological investigations support the fact that there exists a strong influence of N(4)-phenyl substitution in semicarbazone.     

TL and EPR studies of CaSO4:Dy phosphor to investigate its efficacy in measurement of food irradiation dose at sub-ambient temperatures

The effects of sub-ambient temperatures of irradiation and dose response of CaSO₄:Dy phosphor was investigated. The irradiation dose in the range 0.5–7.0 kGy was chosen to meet the requirement of commercial food irradiation at low temperature. Commercially available phosphor showed no significant change in glow curve structure with low temperature of irradiation. In order to enhance the sensitivity of the low temperature glow peak (142 °C), the phosphor was subjected to different post-preparation thermal treatments at 700–900 °C. The change in glows and improvement in dose response characteristics were explained by Electron Paramagnetic Resonance (EPR) spectroscopy. At sub-ambient temperature of irradiation, the behavior of thermally treated CaSO₄:Dy phosphor with increasing dose revealed improved linear response of the low temperature glow peak and could be an efficient dosimetry system for the food commodities irradiated at low temperatures.