Iron(II) phthalocyanine (FePc) over carbon support for oxygen reduction reaction electrocatalysts operating in alkaline electrolyte

Journal of Solid State Electrochemistry - In this work, we initially report a detailed advancement in the utilization of metal-N4 chelate macrocycles in the oxygen reduction reaction (ORR). Then,...     

Synthesis,characterization, and thermal property of phosphate-based cobalt mixture of non-calcined,calcined, and composite material

Monatshefte für Chemie - Chemical Monthly - The phosphate-containing cobalt mixtures of non-calcined, calcined, and composite materials were synthesized in atmospheric conditions and...     

The Assessment of Phytoremediation Potential of Invasive Weed Amaranthus spinosus L.

Presently the environment is heavily polluted by various toxic metals, which creates danger for all living beings. Heavy metals are toxic above certain threshold levels. Phytoremediation is an emerging technology which is quite a novel technique of cleaning polluted sites through the use of plants. Phytoremediation methods are comparatively cheap and ecologically advantageous, compared to conventional and physicochemical methods like precipitation, evaporation and chemical reduction. In this respect, plants can be compared to solar-driven pumps capable of extracting and concentrating certain elements from their environment. Amaranthus spinosus, an invasive weed seen on road sides and bare land belonging to the family Amaranthaceae, was selected for the present study. A greenhouse experiment was conducted and consisted of a range-finding test and definitive test for various concentrations of heavy metals Cu, Zn, Cr, Pb and Cd. Plants were grown in soil treated with different concentration of metals depending upon the threshold level. The bio-organics of the plant such as soluble sugar, protein, lipid, phenol, amino acid and photosynthetic pigments were estimated after 30?days of treatment. The bio-organics showed profound variation in response to accumulation of heavy metals. Accumulation of Cu, Pb and Cd was high in the roots followed by stem and leaves and that of Zn and Cr remained high in aerial parts. A steady increase was noticed in the bioaccumulation of copper, zinc and cadmium on enhancing the concentration of the corresponding metal in the soil. The bioconcentration factor and translocation factor were above unity in most of the treatments and increased as the concentration of treatment increased which indicated that A. spinosus is a potential agent for heavy metal accumulation and translocation.     

Optimizing a CORBA Internet inter-ORB protocol (IIOP) engine forminimal footprint embedded multimedia systems

To support the quality-of-service (QoS) requirements of embedded multimedia applications off-the-shelf middleware like common object request broker architecture (CORBA) must be flexible, efficient, and predictable. Moreover, stringent memory constraints imposed by embedded system hardware necessitates a minimal footprint for middleware that supports multimedia applications. This paper provides three contributions toward developing efficient object request broker's (ORBs) middleware to support embedded multimedia applications. First, we describe optimization principle patterns used to develop a time and space-efficient CORBA inter-ORB protocol (IIOP) interpreter for the adaptive communication environment (ACE)-ORB (TAO), which is our high-performance, real-time ORB. Second, we describe the optimizations applied to TAO's interface definition language (IDL) compiler to generate efficient and small stubs/skeletons used in TAO's IIOP protocol engine. Third, we empirically compare the performance and memory footprint of interpretive (de)marshaling versus compiled (de)marshaling for a wide range of IDL data types. Applying our optimization principle patterns to TAO's IIOP protocol engine improved its interpretive (de)marshaling performance to the point where it is now comparable to the performance of compiled (de)marshaling. Moreover, our IDL compiler optimizations generate interpreted stubs/skeletons whose footprint is substantially smaller than compiled stubs/skeletons. Our results illustrate that careful application of optimization principle patterns can yield both time and space-efficient standards-based middleware     

High-power high-efficiency 0.98-μm wavelengthInGaAs-(In)GaAs(P)-InGaP broadened waveguide lasers grown by gas-sourcemolecular beam epitaxy

We describe the design and experimental results for high-power, high-efficiency, low threshold current, 0.98-μm wavelength, broadened waveguide (BW) aluminum-free InGaAs-(In)GaAs(P)-InGaP lasers. The decrease in the internal losses with an increase in the width of the waveguide layer for a separate-confinement heterostructure multiple-quantum-well (SCW-MQW) structure is attributed to lower free-carrier absorption due to the reduced overlap of the optical mode with the highly doped cladding regions. The BW lasers grown with both InGaAsP and GaAs waveguides show lower internal losses and similar threshold currents than those designed for an optimum optical confinement factor within the QW region. We report a record-low internal loss of 1.8±0.2 cm^-2 for (In)GaAs(P)-InGaP lasers grown by gas-source molecular beam epitaxy (GSMBE). The temperature dependence of internal loss suggests that optical loss from free-carrier absorption in the waveguide dominates at T>40°C, while near room temperature, the residual loss is attributed to scattering and free-carrier absorption in the QW's. The relative insensitivity of internal loss near room temperature has enabled the use of a simplified InGaAs-GaAs-InGaP BW structure to achieve very high CW and quasi-CW (QCW) power operation. We report the highest CW output power of 6.8 W for a GaAs-InGaP laser, and the highest quasi-continuous output power of 13.3 W measured for a single 100-μm-wide aperture, 0.8-0.98-μm wavelength Al-free laser diode grown by GSMBE     

High enantioselective Michael addition of malonates to β,γ-unsaturated α-ketoesters catalyzed by bifunctional thioureas

A highly enantioselective Michael addition of malonates to β,γ-unsaturated α-ketoesters was achieved using cinchona alkaloid-derived thioureas as the bifunctional catalyst. The corresponding Michael addition products were obtained in excellent yields (90–99%) and ee values (up to >99% ee) using a quinidine-derived thiourea as the catalyst under neat conditions. The opposite enantiomer may be obtained using a quinine- or cinchonidine-derived thiourea as the catalyst.     

Monolithic integration of a quantum-well laser and an opticalamplifier using an asymmetric twin-waveguide structure

We demonstrate the monolithic integration of a 1.55 μm wavelength InGaAsP-InP multiple-quantum-well (MQW) laser and a traveling-wave optical amplifier using an asymmetric, vertical twin-waveguide structure. The laser and amplifier share the same strained InGaAsP MQW active layer grown by gas-source molecular beam epitaxy, while the underlying passive waveguide layer is used for on-chip optical interconnections between the active devices. The asymmetric twin-waveguide structure uses the difference in modal gains to discriminate between the even and odd modes     

Resonant tunneling transistor lasers: A new approach to obtain multi-state switching and bistable operation

Bipolar resonant tunneling heterotransistor structures, which can be configured to operate as multi-state or as bistable lasers, are described. Both edge and surface-emitting structures are presented. Computations of various optoelectronics parameters including confinement factor, threshold current density, and cavity modes for a stripe-geometry structure are presented. In addition, simulations of base and collector currents are given for a resonant tunneling transistor to demonstrate the feasibility of lasing in the base region.