Oxidation of styrene over polymer‐ and nonpolymer‐anchored Cu(II) and Mn(II) complex catalysts

Catalytic oxidation of styrene was investigated over polymer‐ and nonpolymer‐anchored Cu(II) and Mn(II) complex catalysts prepared by schiff base tridentate ligands. The effect of temperature, styrene to H₂O₂ mole ratio and catalyst amount on the catalytic activity and product selectivity was investigated. Further, the catalysts were characterized by various techniques, such as elemental analysis, atomic absorption spectroscopy (AAS), FTIR, FE‐SEM, EDAX, TGA, and UV–vis spectrophotometer. The elemental analysis, EDAX and AAS results confirmed the formation of Cu(II) and Mn(II) complexes, and it was found that the metal loading in the polymer‐anchored complex catalysts were in the range of 0.53–3.74 %. FTIR results showed the co‐ordination bond formation between the polymer ligands and metal ion. The catalytic data showed that, over all the catalysts, the main reaction products were benzaldehyde, styrene oxide, and benzoic acid. The polymer‐anchored complex catalysts were found to be much more active when compared with nonpolymer‐anchored catalysts. The maximum conversion of styrene (92.3%) was obtained over PS‐[Cu(Hfsal‐aepy)Cl] catalyst with benzaldehyde selectivity to 69% at the styrene to H₂O₂ mole ratio of 1 : 4 at 75°C. Although the PS‐[Mn(Hfsal‐aepy)Cl] catalyst was less active, it was highly selective to benzaldehyde. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Penalty-free 10 Gbit/s single-channel co-pumped distributed Ramanamplification using low RIN 14xx nm DFB pump

A penalty-free 10 Gbit/s single-channel transmission with co-pumped distributed Raman amplification using a novel high power, low relative integrity noise (RIN), multimode 14xx nm distributed feedback pump is reported. No penalty from pump to signal RIN transfer was observed with co-pumped Raman gains up to 6 dB large effective area fibre (LEAF). In contrast, 0.5 dB penalty was observed with a fibre Bragg grating stabilised pump at 6 dB of Raman gain     

A room temperature process for making Mn2O3 nano-particles and γ-MnOOH nano-rods

Nano-size crystals of Mn₂O₃ and MnOOH have been prepared by a simple precipitation process using dilute aqueous solutions of manganese sulphate and ammonia in the presence of sodium lauryl sulphate — a surface active agent. X-ray diffraction spectrometry has been used to identify the phases and to calculate the size of the nano-size crystals using the Scherrer method. The morphology of the crystals has been studied by TEM/HRTEM and Edax has been used to estimate their elemental constituents. The sonication of the prepared nano-size material in acetone leads to the conversion of MnOOH to nano-sized Mn₂O₃.     

Numerical analysis of inhomogeneous Schottky diode with discrete barrier height patches

The potential profile inside the semiconductor at the metal–semiconductor contact is simulated by numerically solving the Poisson equation and the drift diffusion equations for inhomogeneous Schottky diode. From the simulated potential and the electron and hole concentrations, the drift-diffusion current as a function of bias is calculated. The simulation is carried out for various distribution patterns of barrier height patches at the metal–semiconductor contact to study the effect of barrier inhomogeneities on the Schottky diode parameters, namely barrier height and ideality factor and their temperature dependence. It is found that barrier height decreases and ideality factor increases with increase in the deviation of discrete barrier height patches in the distribution. The resulting barrier parameters are studied to understand the effect of barrier inhomogeneities on the current–voltage characteristics of inhomogeneous Schottky contact.     

A measurement-based approach for power system instability early warning

Early warning of impending instability in a power system under disturbance conditions is important for preventing of system collapse. A measurement-based approach is proposed to assess the potential power system transient instability problem under cascading outages. Where a measurement-based index is obtained as the estimation accuracy of a linear autoregressive exogenous (ARX) model to estimate the dynamic response of the power system and indicate the system stability to some extent after a disturbance. The proposed approach was verified using a set of marginally stable cases in a 179-bus WECC equivalent power system.     

Farmers’ willingness‐to‐pay towards soil and water conservation measures in agro‐ecosystems of Chotanagpur Plateau,India

Lack of importance given to farmers’ knowledge and perceptions towards soil and water conservation (SWC) is a major factor responsible for failure of conservation programs. The study explores farmers understanding of SWC and further adds to the limited empirical evidence towards farmers’ willingness‐to‐pay (WTP) for SWC. Contingent valuation survey conducted to elicit the WTP (cash and labor days) for SWC draws attention to the importance of adopting SWC to ensure year‐round water availability. The willing households of the area could generate US$1302.2 and/or 1207 labor days monthly. The WTP (cash) showed strong positive influence by qualification, total income, off‐farm income and previous irrigation farming experience; while WTP (labor days) showed strong negative influence by age, qualification, dependency ratio, market access and livestock holding. The study will be useful for decision makers regarding investments and policy purposes for soil–water conservation measures in agricultural lands of developing countries.     

Corrosion of laser joined silicon carbide in gasification environment

The production of synthesis gas from renewable fuels is an emerging technology. The aggressive process environment in fuel production systems poses a major challenge, potentially causing corrosion within currently used metallic heat exchangers. To improve the reliability and stability of silicon carbide heat pipes, which belong to an innovative heat exchanger design, the corrosion of involved materials due to contact with steam, ash and alkaline (earth) metals needs to be investigated. Exposures of laser joined SSiC connections with wood ash caused the formation of gas inclusions and an infiltration of the joint with alkaline (earth) metals that lead to crack formations, as revealed by energy dispersive X-ray spectroscopy analysis. It was shown that the use of silicon carbide heat pipes joined with solder materials of both the Mg–Al–Si and the Y–Al–Si systems is possible. A further result was that the gasification temperature has to be limited to 相似文献   

Soluble functionalised fullerenes for photovoltaics

Two mono-adducts of fullerene C₆₀ have been synthesised using new aryl azides in good yields. These were characterized with spectroscopic techniques and then used to fabricate bulk heterojunction solar cells with regioregular poly (3-hexylthiophene) (RR-P3HT). A photocurrent density of 3.89 mA/cm², open-circuit voltage of 0.53 V and power conversion efficiency of 0.89% for adduct I and photocurrent density of 2.93 mA/cm², open-circuit voltage of 0.53 V and power conversion efficiency of 0.71% for adduct II have been achieved.     

In situ formation of silver nanoparticles in poly(methacrylic acid) hydrogel for antibacterial applications

In this study, silver nanoparticles‐loaded poly(methacrylic acid) (PMAAc) hydrogels (HGs) have been produced by using a novel approach that involves equilibration of PMAAc HGs in aqueous solution of Ag(I) ions, followed by their reduction with borohydride. The AgNP/PMAAc composite, so produced, was characterized by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Fourier‐transform infrared, surface plasmon resonance, and differential scanning colorimetry analysis. The composite demonstrated pH‐dependent swelling behavior. The AgNP/PMAAc composites demonstrated fair antibacterial action against Escherichia coli. Their biocidal action was found to depend on the concentration of silver present within the HG and degree of crosslinking of HGs. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

Solid particle erosion wear characteristics of fiber and particulate filled polymer composites: A review

The solid particle erosion behaviour of fiber and particulate filled polymer composites has been reviewed. An overview of the problem of solid particle erosion was given with respect to the processes and modes during erosion with focus on polymer matrix composites. The new aspects in the experimental studies of erosion of fiber and particulate filled polymer composites were emphasised in this paper. Various predictions and models proposed to describe the erosion rate were listed and their suitability was mentioned. Implementation of design of experiments and statistical techniques in analyzing the erosion behaviour of composites was discussed. Recent findings on erosion response of multi-component hybrid composites were also presented. Recommendations were given on how to solve some open questions related to the structure-erosion resistance relationships for polymers and polymer based hybrid composites.