Development and performance comparison of two different approaches for stabilizing a harmonic mode-locked fiber laser at 40 GHz

What we believe to be a new and simple approach was developed for stabilizing a harmonic mode-locked fiber laser at 40 GHz. It uses a computer to tune the modulation frequency in a 100 kHz band near 40 GHz to follow variations in the length of the optical cavity. A second approach was also developed to compare with the new approach and to draw conclusions on its performance. Results for the pulse characteristics, side-mode suppression ratio, and timing jitter show that both approaches provide an efficient way of stabilizing a harmonic FM mode-locked fiber laser.     

Transparent, conductive, and flexible carbon nanotube films and their application in organic light-emitting diodes

We have carried out comparative studies on transparent conductive thin films made with two kinds of commercial carbon nanotubes: HiPCO and arc-discharge nanotubes. These films have been further exploited as hole-injection electrodes for organic light-emitting diodes (OLEDs) on both rigid glass and flexible substrates. Our experiments reveal that films based on arc-discharge nanotubes are overwhelmingly better than HiPCO-nanotube-based films in all of the critical aspects, including surface roughness, sheet resistance, and transparency. Further improvement in arc-discharge nanotube films has been achieved by using PEDOT passivation for better surface smoothness and using SOCl2 doping for lower sheet resistance. The optimized films show a typical sheet resistance of approximately 160 Omega/ square at 87% transparency and have been used successfully to make OLEDs with high stabilities and long lifetimes.     

Independent control of ion transmission in a jet disrupter dual-channel ion funnel electrospray ionization MS interface

A new atmospheric pressure ionization mass spectrometer (API-MS) interface has been developed to allow the control of ion transmission through the first vacuum stage of the mass spectrometer. The described interface uses a dual-heated capillary and a dual-inlet ion funnel design. Two electrosprays, aligned with the dual-capillary inlet, are used to introduce ions from different solutions independently into the MS. The initial design was specifically aimed at developing a method for the controlled introduction of calibrant ions in highly accurate mass measurements using Fourier transform ion cyclotron resonance mass spectrometer (FTICR). The dual-channel ion funnel has different inlet diameters that are aligned with the dual capillaries. The large diameter main channel of the ion funnel is used for analyte introduction to provide optimum ion transmission. The second, smaller diameter channel inlet includes a jet disrupter in the ion funnel to modulate the ion transmission through the channel. The two inlet channels converge into a single-channel ion funnel where ions from both channels are mixed, focused, and transmitted to the mass analyzer. Both theoretical simulations and experimental results show that the transmission of different m/z species in the small diameter channel of the ion funnel can be effectively modulated by varying the bias voltage on the jet disrupter. Both static and dynamic modulations of ion transmission are demonstrated experimentally by applying either a constant DC or a square waveform voltage to the jet disrupter. High ion transmission efficiency, similar to the standard single-channel ion funnel, is maintained in the main analyte channel inlet of the ion funnel over a broad m/z range with negligible "cross talk" between the two ion funnel inlet channels. Several possible applications of the new interface (e.g., for high-accuracy MS analysis of complex biological samples) are described.     

Note: Miniature 120-kV autonomous generator based on transverse shock-wave depolarization of Pb(Zr0.52Ti0.48)O3 ferroelectrics

The design of autonomous ultrahigh-voltage generators with no moving metallic parts based on transverse explosive shock wave depolarization of Pb(Zr(0.52)Ti(0.48))O(3) (PZT 52∕48) poled ferroelectrics was explored and studied. It follows from experimental results that the output voltage produced by the shock-wave ferroelectric generators (FEGs) is directly proportional to the number of PZT 52/48 elements connected in series. It was demonstrated that miniature FEGs (volume less than 180 cm(3)) were capable of reliably producing output voltage pulses with amplitudes exceeding 120 kV which is the record reported in open literature.     

Experimental study of phase equilibria in the Al-Fe-Zn-O system in air

The phase equilibria in the Al-Fe-Zn-O system in the range 1250 °C to 1695 °C in air have been experimentally studied using equilibration and quenching techniques followed by electron probe X-ray microanalysis. The phase diagram of the binary Al₂O₃-ZnO system and isothermal sections of the Al₂O₃-“Fe₂O₃”-ZnO system at 1250 °C, 1400 °C, and 1550 °C have been constructed and reported for the first time. The extents of solid solutions in the corundum (Al,Fe)₂O₃, hematite (Fe,Al)₂O₃, Al₂O₃*Fe₂O₃ phase (Al,Fe)₂O₃, spinel (Al,Fe,Zn)O₄, and zincite (Al,Zn,Fe)O primary phase fields have been measured. Corundum, hematite, and Al₂O₃*Fe₂O₃ phases dissolve less than 1 mol pct zinc oxide. The limiting compositions of Al₂O₃*Fe₂O₃ phase measured in this study at 1400 °C are slightly nonstoichiometric, containing more Al₂O₃ then previously reported. Spinel forms an extensive solid solution in the Al₂O₃-“Fe₂O₃”-ZnO system in air with increasing temperature. Zincite was found to dissolve up to 7 mole pct of aluminum in the presence of iron at 1550 °C in air. A meta-stable Al₂O₃-rich phase of the approximate composition Al₈FeZnO_14+x was observed at all of the conditions investigated. Aluminum dissolved in the zincite in the presence of iron appears to suppress the transformation from a round to platelike morphology.     

VIR-Process of Coal Firing at the Ryazanskaya State Regional Power Plant

Results of the first reconstruction in Russia of a P-59 boiler at a 300-MW generating unit of the Ryazanskaya State Regional Power Plant employing a novel firing process (VIR-method) are presented. The transfer to the VIR-process considerably increases the long-term, slag-free output of the boiler, improves the ecological parameters, and lowers the cost of repair.