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Long Lifetime (long + lifetime)
Selected AbstractsLarge-Scale Synthesis of Long Crystalline Cu2-xSe Nanowire Bundles by Water-Evaporation-Induced Self-Assembly and Their Application in Gas SensingADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Jun Xu Abstract By a facile water evaporation process without adding any directing agent, Cu2-xSe nanowire bundles with diameters of 100,300,nm and lengths up to hundreds of micrometers, which comprise crystalline nanowires with diameters of 5,8,nm, are obtained. Experiments reveal the initial formation/stacking of CuSe nanoplates and the subsequent transformation to the Cu2-xSe nanowire bundles. A water-evaporation-induced self-assembly (WEISA) mechanism is proposed, which highlights the driving force of evaporation in promoting the nanoplate stacking, CuSe-to-Cu2-xSe transformation and the growth/bundling of the Cu2-xSe nanowires. The simplicity, benignancy, scalability, and high-yield of the synthesis of this important nanowire material herald its numerous applications. As one example, the use of the Cu2-xSe nanowire bundles as a photoluminescence-type sensor of humidity is demonstrated, which shows good sensitivity, ideal linearity, quick response/recovery and long lifetime in a very wide humidity range at room temperature. [source] High-Gain Broadband Solid-State Optical Amplifier using a Semiconducting Copolymer,ADVANCED MATERIALS, Issue 1 2009Dimali Amarasinghe A dilute fluorene copolymer produces enhanced optical amplification. High gain with 1000 times optical amplification and a long lifetime is achieve in only 1mm of the material, and exciton,exciton annihilation is suppressed. [source] Architectural support in industry: a reflection using C-POSHJOURNAL OF SOFTWARE MAINTENANCE AND EVOLUTION: RESEARCH AND PRACTICE, Issue 1 2005R. J. Bril Abstract Software architecture plays a vital role in the development (and hence maintenance) of large complex systems (containing millions of lines of code) with a long lifetime. It is therefore required that the software architecture is also maintained, i.e., sufficiently documented, clearly communicated, and explicitly controlled during its life-cycle. In our experience, these requirements cannot be met without appropriate support. Commercial-off-the-shelf support for architectural maintenance is still scarcely available, if at all, implying the need to develop appropriate proprietary means. In this paper, we reflect upon software architecture maintenance taken within three organizations within Philips that develop professional systems. We extensively describe the experience gained with introducing and embedding of architectural support in these three organizations. We focus on architectural support in the area of software architecture recovery, visualization, analysis, and verification. In our experience, the support must be carried by a number of pillars of software development, and all of these pillars have to go through a change process to ensure sustainable embedding. Managing these changes requires several key roles to be fulfilled in the organization: a champion, a company angel, a change agent, and a target. We call our reflection model C-POSH, which is an acronym for Change management of the four identified pillars of software development: Process, Organization, Software development environment, and Humans. Our experiences will be presented in terms of the C-POSH model. Copyright © 2005 John Wiley & Sons, Ltd. [source] A novel gaseous dimethylamine sensor utilizing cataluminescence on zirconia nanoparticlesLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 5 2009Chao Yu Abstract A novel cataluminescence (CTL) sensor using ZrO2 nanoparticles as the sensing material was developed for the determination of trace dimethylamine in air samples based on the catalytic chemiluminescence (CL) of dimethylamine on the surface of ZrO2 nanoparticles. The CTL characteristics and the different factors on the signal intensity for the sensor, including nanomaterials, working temperature, wavelength and airflow rate, were investigated in detail. The CL intensity on ZrO2 nanoparticles was the strongest among the seven examined catalysts. This novel CL sensor showed high sensitivity and selectivity to gaseous dimethylamine at optimal temperature of 330°C. Quantitative analysis was performed at a wavelength of 620 nm. The linear range of CTL intensity vs concentration of gaseous dimethylamine was 4.71 × 10,3 to 7.07 × 10,2 mg L,1 (r = 0.9928) with a detection limit (3,) of 6.47 × 10,4 mg L,1. No or only very low levels of interference were observed while the foreign substances such as benzene, hydrochloric acid, methylbenzene, chloroform, n -hexane and water vapor were passing through the sensor. The response time of the sensor was less than 50 s, and the sensor had a long lifetime of more than 60 h. The sensor was successfully applied to the determination of dimethylamine in artificial air samples, and could potentially be applied to analysis of nerve agents such as Tabun (GA). Copyright © 2009 John Wiley & Sons, Ltd. [source] Long life operations over 5000 hours of BeZnSeTe/MgZnCdSe visible light emitting diodes on InP substratesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2006Ichirou Nomura Abstract Aging characteristics of BeZnSeTe yellow light emitting diodes (LEDs) fabricated on InP substrates by molecular beam epitaxy were investigated under direct current injections at room temperature. It was shown that the decay speed of the light output during the aging was slower than that of conventional ZnCdSe/MgZnSSe LEDs. A long lifetime more than 5000 h and a half lifetime of 5180 h were obtained at a current density of 130 A/cm2. The half lifetimes of the BeZnSeTe LEDs were about three orders of magnitude greater than that of the ZnCdSe/MgZnSSe LEDs. These results proved high reliability of the BeZnSeTe LED. Investigating the aging characteristics of the applied voltage, the injection current, and the emission spectra showed that the output decay was caused by degradation of the active layer of the LEDs. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Quantum dot-tagged microspheres for fluid-based DNA microarraysPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003K. E. Meissner Abstract Quantum dot-embedded microspheres offer a promising technology for the development of a fluid-based DNA microarray to replace current biochip microarray technology. The narrow emission and long lifetime from the quantum dots (QD's) is ideal for dense spectral multiplexing. Also, the QD's may all be excited by a single source. To implement this solution, we have fabricated CdSe quantum dots following published procedures and embedded them in polystyrene microspheres. As a first step in this development, we have investigated the use of a flow cytometer in analyzing the encoded microspheres. We demonstrate the use of a microsphere-based DNA detection system and investigate the readout of quantum dot-tagged microspheres. We also discuss some of the inherent limitations and difficulties of using such a system to address the need for a high-throughput readout for spectral multiplexing for fluid-based DNA microarrays. [source] Amphiphilic polyelectrolyte for stabilization of multiple emulsions,POLYMER INTERNATIONAL, Issue 4 2003Fanny Michaut Abstract Multiple emulsions are complex thermodynamically unstable systems where both types of emulsion coexist. We investigated the stability behaviour of water-in-oil-in-water (W/O/W) emulsions formulated with a hydrophobically modified poly(sodium acrylate) emulsifier at the outer interface and a monomeric surfactant (span 80) at the inner interface. Their stability was tested through release kinetics of a marker (NaCl) initially encapsulated in the aqueous droplets, and by rheology. Slow release rates and remarkably long shelf-life were obtained compared to typical multiple emulsions stabilized by two commonly used surfactants (span 80 and tween 20). In addition, we prepared stable highly concentrated multiple emulsions. Their rheological behaviour indicated that the internal interface was essentially covered with span 80. Thus, transportation of the polymer across the oil phase is limited, which in turn explains, at least partially, the stability improvement in the presence of the polymeric emulsifier. Finally, the long lifetime of the emulsions allowed study by diffusing wave spectroscopy of the interactions between the droplets and the globule surface which are important for understanding the destruction mechanisms of multiple emulsions. © 2003 Society of Chemical Industry [source] Magnetically Suspended Rotary Blood Pump with Radial Type Combined Motor-BearingARTIFICIAL ORGANS, Issue 6 2000Toru Masuzawa Abstract: A magnetically suspended centrifugal blood pump is being developed with a combined motor-bearing for long-term ventricular assist systems. The combined motor-bearing actively suspends a rotor in a radial direction to deal with radial force unbalance in the pump and rotates the rotor by using the electric magnetic field. Therefore, the pump has no mechanical parts such as bearings of the motor and has a long lifetime. The developed pump consists of a thin rotor with a semi open-type 6 vane impeller and a stator to suspend and rotate the rotor. The rotor has 4-pole permanent magnets on the circumferential surface. The outer diameter and the thickness of the rotor are 60 mm and 8 mm, respectively. Axial movement and tilt of the rotor are restricted by passive stability based on the thin rotor structure. Radial movements of the rotor, such as levitation in radial direction and rotation, are controlled actively by using electric magnets of the stator. The electric magnet coils to produce levitation and rotation forces are constructed on the periphery stator. The p ± 2-pole algorithm and the synchronous motor mechanism are adopted to levitate and rotate the rotor. The radial gap between the rotor and the stator is 1 mm. A closed-loop circuit filled with water was connected to the developed pump to examine the basic performance of the pump and the magnetic suspension system. Maximum rotational speed, flow rate, and head were 2,800 rpm, 11 L/min, and 270 mm Hg, respectively. The rotor with the impeller could be suspended completely during the entire pumping process. We conclude the pump with the combined motor-bearing has sufficient performance for the blood pump. [source] Oxidation of PCE with a UV LED Photocatalytic ReactorCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2005D. H. Chen Abstract This paper is the first to investigate photocatalysis using a cutting-edge and energy-efficient solid-state light source: Ultraviolet (UV) Light Emitting Diodes (LED's). UV LED's do not involve mercury vapor, can be driven with direct current (DC), and have a long lifetime of 100,000 hours. UV LED's with a peak wavelength of 375,nm were tested for perchloroethylene (PCE) photocatalytic oxidation over Degussa P,25 TiO2. At a UV light output of only 49,,W/cm2, the designed reactor delivers a PCE conversion of up to 43,%. If the UV LED price continues to drop, it is very likely that UV LED's will replace UV lamps as the favored light source in photocatalysis applications. [source] X-ray Crystal Structure of a Sodium Salt of [Gd(DOTP)]5,: Implications for Its Second-Sphere Relaxivity and the 23Na NMR Hyperfine Shift Effects of [Tm(DOTP)]5,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2003Fernando Avecilla Abstract The X-ray structure of the sodium salt of [Gd(DOTP)]5, shows two different chelates, [Gd(1)(DOTP)]5, and [Gd(2)(DOTP)]5,, bound at either surface of a sheet formed by a cluster of hydrated Na+ ions. Each [Gd(1)(DOTP)]5, anion binds directly to four Na+ ions of this cluster through the free oxygen atoms of the phosphonate groups of the adjacent ligand, while each [Gd(2)(DOTP)]5, unit is connected to the cluster via hydrogen bonds only. The Gd3+ ions in the two moieties do not have any inner-sphere water molecules, and are eight-coordinate. Their coordination polyhedra are twisted square antiprisms, with slightly different twist angles. These m, isomers are found in the crystal structure as racemic mixtures of enantiomers. Only one set of NMR resonances is observed in aqueous solution, corresponding to an averaged m, isomer. In this crystal structure, the Na+ ions bind the phosphonate oxygen atoms of the [Gd(1)(DOTP)]5, anion at positions far removed from the main symmetry axis. This is significantly different from the binding mode(s) previously proposed to be occurring in solution between Na+ and [Tm(DOTP)]5,, based on the interpretation of solution paramagnetic 23Na NMR shifts. This could arise as a result of the effects of the cluster of hydrated Na+ ions that are present, which may hinder axial binding modes and distort lateral binding modes. Further, in the crystal structure, both types of Gd3+ centers have four second-sphere water molecules that are located at distances (4.2,4.5 Å) significantly longer than those previously proposed from the analysis of the NMRD data of [Gd(1)(DOTP)]5,. This is a result of the coordination of Na+ by these water molecules, thus preventing their direct interaction with the phosphonate oxygen atoms. However, in solution such second-sphere water molecules can interact strongly with the phosphonate ligand oxygen atoms, resulting in efficient relaxation if their binding has relatively long lifetimes (> 50 ps). Rotational immobilization will amplify this contribution, thus making it similar to outer-sphere relaxation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Synthesis and Photophysical Properties of a Pyrazolino[60]fullerene with Dimethylaniline Connected by an Acetylene LinkageEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2006Andreas Gouloumis Abstract A new triad based on pyrazolino[60]fullerene and a conjugated dimethylaniline group has been synthesized by a copper-free Sonogashira cross-coupling reaction using microwave irradiation as the source of energy. The electrochemical and photophysical properties of the triad were systematically investigated by techniques such as time-resolved fluorescence and transient absorption spectroscopy. Charge separation via the excited singlet state of the C60 moiety was confirmed in polar and nonpolar solvents and competes with triplet formation of the C60 moiety. The charge-separated state persisted for 91 ns. Such long lifetimes are characteristic of long distances between the radical anion of the pyrazolino[60]fullerene derivative and the radical cation of the dimethylaniline moiety. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Computational analyses of singlet,singlet and singlet,triplet transitions in mononuclear gold-capped carbon-rich conjugated complexesJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 12 2005Zexing Cao Abstract Density functional theory and CASSCF calculations have been used to determine equilibrium geometries and vibrational frequencies of metal-capped one-dimensional ,-conjugated complexes (H3P)Au(CC)n(Ph) (n = 1,6), (H3P)Au(CCC6H4)(CCPh), and H3PAu(CCC6H4)CCAuPH3 in their ground states and selected low-lying ,,* excited states. Vertical excitation energies for spin-allowed singlet,singlet and spin-forbidden singlet,triplet transitions determined by the time-dependent density functional theory show good agreement with available experimental observations. Calculations indicate that the lowest energy 3(,,*) excited state is unlikely populated by the direct electronic excitation, while the low-lying singlet and triplet states, slightly higher in energy than the lowest triplet state, are easily accessible by the excitation light used in experiments. A series of radiationless transitions among related excited states yield the lowest 3(,,*) state, which has enough long lifetimes to exhibit its photochemical reactivities. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1214,1221, 2005 [source] Current collapse and reliability of III-N heterostructure field effect transistorsPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 3 2007A. Koudymov Abstract Measurements of GaN HFET lifetime as a function of temperature show that different degradation mechanisms are involved at low temperatures (close to room temperature) and high temperatures (above 150 °C). The degradation at low temperatures is linked to the trap generation and can be explained using the current collapse model. At higher tempe- ratures, other degradation mechanisms become important or even dominant. The current collapse related degradation can be diminished by using improved device design, which will greatly increase the overall lifetime (up to long lifetimes obtained by extrapolating high temperature data to room temperature). (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||||||||