Nanoscale films of organic dyes for broadband environmental sensing

Two types of suitably substituted organic dye molecules namely copper phthalocyanine and Rose Bengal were electrostatically self-assembled on gold-coated glass substrates, the gold surface being modified with poly(allylaminehydrochloridethe). The surface plasmon resonance technique was employed to investigate the sensing properties of organic dyes on exposure to three different volatile organic compounds. The films using phthalocyanine molecules were considered to be an optimal material because of its fast response and full recovery. This behaviour is attributed to the film surface morphology, molecular orientation in the film architecture, and sizes and dipole moments of vapours.     

Colorimetric study of SCOTDIC colour specifier

In this study, SCOTDIC cotton standard colours (a physical exemplification of the Munsell system) were studied extensively. L*, a*, b* values were measured and plotted to check the uniformity of the Munsell (SCOTDIC) hue, value and chroma values in a CIELAB diagram. Although for some borderline hues the hue angles were quite different than expected (around 0° or 360°), the correlation between SCOTDIC hue and CIELAB hue angle was fairly good and the correlation between SCOTDIC value and CIELAB lightness was also quite high. However, the correlation between SCOTDIC chroma and CIELAB chroma was only moderate. In the CIELAB diagram, the constant SCOTDIC hue and constant chroma loci took the shape of approximately linear radial lines starting from the origin and approximately concentric circles with the origin as their centres, respectively. However, some deviations were observed for high chroma colours and yellow hues in the respective cases. The instrumentally predicted Munsell notations were compared with the actual SCOTDIC notations. Some deviations of the SCOTDIC system from the Munsell system were observed.     

High-mobility solution-processed copper phthalocyanine-based organic field-effect transistors

Solution-processed films of 1,4,8,11,15,18,22,25-octakis(hexyl) copper phthalocyanine (CuPc₆) were utilized as an active semiconducting layer in the fabrication of organic field-effect transistors (OFETs) in the bottom-gate configurations using chemical vapour deposited silicon dioxide (SiO₂) as gate dielectrics. The surface treatment of the gate dielectric with a self-assembled monolayer of octadecyltrichlorosilane (OTS) resulted in values of 4×10⁻² cm² V⁻¹ s⁻¹ and 10⁶ for saturation mobility and on/off current ratio, respectively. This improvement was accompanied by a shift in the threshold voltage from 3 V for untreated devices to -2 V for OTS treated devices. The trap density at the interface between the gate dielectric and semiconductor decreased by about one order of magnitude after the surface treatment. The transistors with the OTS treated gate dielectrics were more stable over a 30-day period in air than untreated ones.     

Development and application of vanadium oxide/polyaniline composite as a novel cathode catalyst in microbial fuel cell

Polyaniline (Pani), vanadium oxide (V₂O₅), and Pani/V₂O₅ nanocomposite were fabricated and applied as a cathode catalyst in Microbial Fuel Cell (MFC) as an alternative to Pt (Platinum), which is a commonly used expensive cathode catalyst. The cathode catalysts were characterized using Cyclic Voltammetry and Linear Sweep Voltammetry to determine their oxygen reduction activity; furthermore, their structures were observed by X‐ray Diffraction, X‐ray Photoelectron Spectroscopy, Brunauer–Emmett–Teller, and Field‐Emission Scanning Electron Microscopy. The results showed that Pani/V₂O₅ produced a power density of 79.26 mW/m², which is higher than V₂O₅ by 65.31 mW/m² and Pani by 42.4 mW/m². Furthermore, the Coulombic Efficiency of the system using Pani/V₂O₅ (16%) was higher than V₂O₅ and Pani by 9.2 and 5.5%, respectively. Pani–V₂O₅ also produced approximately 10% more power than Pt, the best and most common cathode catalyst. It declares that Pani–V₂O₅ can be a suitable alternative for application in a MFC system. Copyright © 2013 John Wiley & Sons, Ltd.     

Vibrational spectroscopic studies on crystallisation of sol–gel derived thin films of calcia–alumina binary compound

An optimized sol–gel process has been developed to produce homogeneous thin films of calcium aluminate binary (12CaO·7Al₂O₃) compound, on magnesium oxide substrates via spin coating. Fourier transform infrared and Raman spectroscopies have been employed to investigate the effect of annealing temperature and duration on the phase transformations in the films. Heat treatment at 1,300 °C under air atmosphere for 2 h produced single-phase 12CaO·7Al₂O₃ films. However, annealing at a lower temperature of 1,100 °C in air for a period of 4 h in total resulted in the crystallization of 5CaO·3Al₂O₃ rather than 12CaO·7Al₂O₃. The X-ray photoelectron spectrum of the thin film annealed at 1,300 °C corresponds to the binding energies of C12A7 compound. The annealing temperature of 1,300 °C for 2 h is found to be sufficient for formulating single phase calcia–alumina binary films in correct stoichiometric ratio of 12:7.     

Stabilization of Euler-Bernoulli Beam Equation with Boundary Moment Control and Disturbance by Active Disturbance Rejection Control and Sliding Mode Control Approaches

We consider boundary stabilization for a one-dimensional Euler-Bernoulli equation with boundary moment control and disturbance. The active disturbance rejection control (ADRC) and sliding mode control (SMC) approaches are adopted in investigation. By the ADRC approach, a state feedback disturbance estimator with time-varying gain is designed to estimate the disturbance. It is shown that the closed-loop system is asymptotically stable by canceling the disturbance in the feedback loop with its online estimation. In the second part, the SMC is applied to reject the disturbance. The well-posedness of the closed-loop system via SMC is proven, and the monotonicity of the “reaching condition” is presented without differentiating the sliding mode function which may not always exist for the weak solution. The numerical experiments are presented to illustrate the convergence and the peaking value reduction caused by the constant high gain. In addition, the control energies are compared numerically for two approaches.     

铬鞣的新视角

从碱式硫酸铬溶液的耐碱性能出发,逐步阐述了铬粉的种类与质量,碱化剂的种类与质量以及应用的方法对生产高质量蓝革的重要性。另外,简短回顾了鞣制技术对于蓝革质量的影响。     

A scheme for generating electricity using gravitational energy

A practical scheme for generating electricity using gravitational energy is presented. The scheme uses a set of massive underground spinning wheels, each wheel being fitted with a mechanism to receive and transmit gravitational torque pulses from a passing vehicle to keep the wheels in motion. Each wheel in combination with an appropriate gear system then acts as the prime mover of an alternator which produces the electricity. Design formulae relating to the power gain and the overall efficiency of the energy system are then developed. The numerical results presented in the paper indicate that a power gain of as high as 10 and an associated efficiency of conversion close to 92% can be easily achieved with a reasonable design of the system.     

Effect of Shallowness on Sediment Deposition in Recirculation Zones

Various hydrodynamic and sediment deposition experiments were conducted on a purpose-built, wide, shallow water table using a range of incoming flow and bed roughness conditions, including five flow rates, different inflow sediment concentrations, and different artificial roughness coefficients generated by four transverse string intervals. A recirculation zone was created behind a 0.5-m-wide backward-facing step on the left side of the table. Surface velocities, sediment concentrations, and processes and features of sediment deposition in recirculation zones were measured. Experimental results indicate that (1)?as the value of the shallow stability parameter increased from 0.033 to 0.47, the length of the recirculation zone decreased to less than half, but the corresponding area and volume of sediment deposition increased about four times, and (2)?it is the strength of the mixing layer rather than the size of the recirculation zone that dominates the process of sediment deposition as well as the final deposition feature.