LMI Optimization Approach to Observer-Based Controller Design of Uncertain Time-Delay Systems via Delayed Feedback

In this paper, we propose a design method of an observer-based controller for uncertain time-delay systems by delayed feedback. Based on the Lyapunov method, an LMI (linear matrix inequality) criterion is derived to design an observer-based controller which makes the system stable. A numerical example is included to illustrate the design procedure.     

Effect of pressure and temperature on chromophore reorientation in a new syndioregic main‐chain hydrazone nonlinear optical polymer

Second harmonic generation (SHG) was used to measure the temperature dependence of the reorientation activation volume (ΔV*) of a syndioregic main‐chain hydrazone (SMCH) nonlinear optical polymer. The decay of the SHG signal from poled films of SMCH was recorded at hydrostatic pressures up to 2924 atm and at temperatures between 25 °C below the glass‐transition temperature (T_g) to 20 °C above it. ΔV* for pressures less than 500–1000 atm and T > T_g decreased as the temperature was increased. For pressures greater than 1000 atm, ΔV* was essentially constant for all temperatures. In addition, the size of ΔV* indicated that the chromophore in this main chain was internally flexible. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 895–900, 2001     

Comparative Solution Synthesis of Mn Doped (Na,K)NbO3 Thin Films

(K_0.5Na_0.5)NbO₃ (KNN) is a promising lead-free alternative for ferroelectric thin films such as Pb(Zr,Ti)O₃. One main drawback is its high leakage current density at high electric fields, which has been previously linked to alkali non-stoichiometry. This paper compares three acetate-based chemical solution synthesis and deposition methods for 0.5 mol % Mn-doped KNN film fabrication, using lower crystallization temperature processes in comparison to the sintering temperatures necessary for fabrication of KNN ceramics. This paper shows the crucial role of the A site homogenization step during solution synthesis in preserving alkali chemical homogeneity of Mn doped KNN films. Chemically homogeneous films show a uniform grain size of 80 nm and a leakage current density under 2.8×10⁻⁸ A cm⁻² up to electric fields as high as 600 kV cm⁻¹, which is the highest breakdown strength reported for KNN thin films. Solution synthesis involving two-step pyrolysis resulted in films with dense, columnar microstructures, which are interesting for orientation control and enhancement of piezoelectric properties. This study reports detailed solution synthesis and deposition processes with good dielectric, ferroelectric and breakdown field properties. An optimized fabrication method that should couple low leakage current density with dense and oriented microstructures is proposed.     

Recent application of biochar on the catalytic biorefinery and environmental processes

Lignocellulosic biomass is an abundant and environment-friendly source for renewable energy production. The value and application of biochar, which is obtained from the thermochemical conversion of biomass, is increasing rapidly because of its high carbon content and porosity. The property of biochar, such as surface area, porosity, and number of functional groups, can be improved by controlling the conditions of biomass conversion, biochar activation, and functionalization methods. The production and activation of biochar as well as its potential use for soil remediation, pollutant adsorption, and biorefinery have been reviewed extensively over recent decades. This paper provides a conceptual approach for biochar production and activation together with its application as a catalyst for biorefineries and the removal of environmental contaminants.     

Synthesis,characterisation, and X-ray structures of zinc(II) complexes bearing camphor-based ethyleneamineimines as pre-catalysts for heterotactic-enriched polylactide from rac-lactide

Transition Metal Chemistry - A series of Zn(II) complexes bearing camphor-based ethyleneamine derivatives, [LnZnCl2]...     

Ancillary Ligand Effects on Heteroleptic IrIII Dye in Dye-Sensitized Photocatalytic CO2 Reduction: Photoaccumulation of Charges on Arylated Bipyridine Ligand and Its Control on Catalytic Performance

Herein, we report the synthesis, and photochemical and -physical properties, as well as the catalytic performance, of a series of heteroleptic Ir^III photosensitizers (IrPSs), [Ir(C^N)₂(N^N^Aryl)]⁺, possessing ancillary ligands that are varied with aryl-substituents on bipyridyl unit [C^N=(2-pyridyl)benzo[b]thiophen-3-yl (btp); N^N^Aryl=4,4′-Y₂-bpy (Y=−Ph or −PhSi(Ph)₃]. We found that the π-extension of bipyridyl ligand by aryl-substitution put bipyridyl ligand in use as an electron relay unit that performed charge accumulation before delivering to the catalytic center, greatly improving the overall CO₂-to-CO conversion activities. In a typical run, the aryl-substituted IrPS ( ^{t Bu} IrP-Ph^Si )-sensitized homogeneous systems (IrPS+Re^I catalyst) gave a turnover number of 1340 (Φ_CO=24.2 %) at the early stage of photolysis (<5 h). This study demonstrates that the π-character modulation on the ancillary bipyridyl ligand is critical for forthcoming catalytic performance.     

Characterization of O+ Ion-implanted Glassy Carbon Using the Superconducting Electron Cyclotron Resonance Ion Source and Selective Dopamine Detection

The O and N gas ions (O³⁺, O⁺, N²⁺, and N⁴⁺) were implanted on the glassy carbon surface employing the electron cyclotron resonance ion source, which were characterized using electrochemical and surface analysis methods. The modified electrode was examined for the catalytic oxidation of bioorganic molecules including dopamine, where the O⁺ ion implanted GC revealed the best catalytic performance. The XPS and Raman results represented that the ion implantation made enrichment in graphite nanocrystalline structure with edge plane, showing the enhanced electrochemical activity. It showed excellent performance for dopamine detection without significant interferences between 50.0 nM and 400.0 μM with the detection limit of 10.0±2.5 nM (95 % confidence level). The reliability of proposed electrode was evaluated by the real urine sample analysis.