A new general Routh-like algorithm to determine the number of RHP roots of a real or complex polynomial

A new Routh-like algorithm for determining the number of right-half plane (RHP) roots of a polynomial with real or complex coefficients is given. It includes the Routh algorithm for real polynomials as a special case. Moreover, the algorithm also applies directly to the singular case wherein the leading coefficient of a row, but not the entire row, vanishes, needing far fewer computations than the heuristicepsilon- method about which there was a vigorous discussion in these TRANSACTIONS a few years ago, and further not requiring investigation of an auxiliary polynomial. The algorithm is illustrated by a few examples. The proof of the algorithm is based on the Principle of the Argument, and thus also constitutes a simple proof of the Routh algorithm in the regular case.     

Probing the dynamics of nanoparticle growth in a flame using synchrotron radiation

Flame synthesis is one of the most versatile and promising technologies for large-scale production of nanoscale materials. Pyrolysis has recently been shown to be a useful route for the production of single-walled nanotubes, quantum dots and a wide variety of nanostructured ceramic oxides for catalysis and electrochemical applications. An understanding of the mechanisms of nanostructural growth in flames has been hampered by a lack of direct observations of particle growth, owing to high temperatures (2,000 K), rapid kinetics (submillisecond scale), dilute growth conditions (10(-6) volume fraction) and optical emission of synthetic flames. Here we report the first successful in situ study of nanoparticle growth in a flame using synchrotron X-ray scattering. The results indicate that simple growth models, first derived for colloidal synthesis, can be used to facilitate our understanding of flame synthesis. Further, the results indicate the feasibility of studies of nanometre-scale aerosols of toxicological and environmental concern.     

Development of transparent and conductive ZnO films by spray pyrolysis

Indium-doped zinc oxide (IZO) films were deposited on Corning 7059 substrates by the spray pyrolysis technique. To achieve higher electrical conductivity both the zinc acetate concentration and indium concentration in the solution were varied. The films were characterized for their structural and electrical properties. Film stability in H₂ plasma was also checked for possible use in amorphous and microcrystalline silicon related fields. It was observed that the films can be sustained in a hydrogen plasma, and hence IZO films of high conductivity can be used for the development of amorphous and microcrystalline silicon solar cells.     

An InP-Based Monolithically Integrated Reconfigurable Optical Add–Drop Multiplexer

We demonstrate an InP-based monolithically integrated reconfigurable optical add-drop multiplexer consisting of an array waveguide grating, a semiconductor optical amplifier, four 2x2 Mach-Zehnder optical switches, and four PIN photodetectors using the asymmetric twin waveguide technology. The total chip size is 10 x 6 mm, and each of the components in the circuit exhibited performance similar to that achieved in a discrete form. The add-drop functionality of the chip is demonstrated via the routing of the signal from the add port to the drop/output port.     

High-Yield Synthesis of Nanocrystalline Tin Dioxide by Thermal Decomposition for Use in Gas Sensors

High-yield synthesis of nanocrystalline tin dioxide (nano-SnO₂) using a two-step thermal decomposition process is reported. Stannous chloride with glacial acetic acid was the precursor to form tin diacetate, whose thermal decomposition gave nano-SnO₂. The yield of respective steps matched well with theoretically expected values, by 85% for tin diacetate and by 94% for nano-SnO₂. Material characterization was done using X-ray diffraction (phase and particle size) and transmission electron microscopy. The nano-SnO₂ particles were successfully used to develop thick film H₂ sensors. The sensor characteristics were closely related to the micro-structural properties of nano-SnO₂.     

Doping optimization and surface modification of aluminum doped zinc oxide films as transparent conductive coating

Aluminum doped zinc oxide (ZnO:Al) films were grown using spray pyrolysis technique. Effect of doping on structural, electrical, optical and morphological properties was studied. Aluminum doping improved the prominence of [002] growth while maintaining the grain size ~ 48 nm. Using an intermediate Al/Zn atomic ratio in precursor (1.5:100), we could achieve a low resistivity ρ ~ 7 × 10^− 4 Ωcm. These films possessed an average visible transmittance ~ 88%, an optical gap ~ 3.7 eV and plasma wavelength at 1.87 μm. A simultaneous use of methanol and iso-propanol in the precursor lead to a moderate surface roughness ~ 12 nm. The films were surface modified using wet chemical etching in diluted hydrochloric acid, for varied time intervals (5 s-15 s) and etchant concentrations (0.125%-1%). The etching experiments could be used to know the building of the film as also to modify the surface for desired optical and morphological properties.     

Compact polarization-insensitive InGaAsP-InP 2 /spl times/ 2 optical switch

We demonstrate a simple, compact, high-contrast ratio, and low-loss polarization-insensitive InGaAsP-InP 2 /spl times/ 2 optical switch with an operational wavelength range from 1520 to 1580 nm. The switch is 1.3 mm long by 160 /spl mu/m wide. The on-off contrast ratio is within (21/spl plusmn/2) dB over the temperature range from 16/spl deg/C to 64/spl deg/C, the polarization sensitivity is <2 dB, and the propagation loss is (3/spl plusmn/2) dB in both the ON and OFF states, making it potentially useful for optical cross-connects, delay lines, and add-drop multiplexers.     

A Highly Selective and Sensitive H2S Gas Sensor Based on Novel Nanostructure Core–Shell FeCr2O4@ZnO@MgO

Journal of Inorganic and Organometallic Polymers and Materials - Gas detection is significant for controlling industrial and vehicle emission, house equipment security and environmental monitoring....     

Effect of heavy doping in SnO2:F films

Thin films of fluorine-doped tin dioxide (SnO₂:F) were deposited by a spray pyrolysis technique on soda lime glass substrates. Structural and electronic transport properties of the films deposited with different doping levels of fluorine (zero to 350 at %) were investigated. X-ray diffraction technique and Hall effect measurements were used for this work. Growth rate of the films was considerably affected by doping, specially at higher doping levels. The films were polycrystalline and preferentially oriented along [200]. This preferred growth played a dominant role in determining the transport properties. Notably the charge carrier mobility was directly governed by this preferred growth. The electrical conductivity was totally governed by the carrier concentration. The respective changes in carrier concentration were used to suggest the site selection of the fluorine dopant in the SnO₂ lattice.