Room temperature single-photon Source:Single-dye molecule fluorescence in Liquid Crystal host

We report on new approaches toward an implementation of an efficient, room temperature, deterministically polarized, single-photon source (SPS) on demand-a key hardware element for quantum information and quantum communication. Operation of a room temperature SPS is demonstrated via photon antibunching in the fluorescence from single terrylene-dye molecules embedded in a cholesteric liquid crystal host. Using oxygen-depleted liquid crystal hosts, dye-bleaching was avoided over the course of more than 1 h of continuous 532-nm excitation. Liquid crystal hosts (including liquid crystal oligomers/polymers) permit further increase of the efficiency of the source: 1) by aligning the dye molecules along a direction preferable for maximum excitation efficiency; 2) by tuning a one-dimensional (1-D) photonic-band-gap microcavity of planar-aligned cholesteric (chiral nematic) liquid crystal layer to the dye fluorescence band.     

Fabrication of MgO-coated TiO2 nanotubes and application to dye-sensitized solar cells

Dye-sensitized solar cells (DSCs) are more spotlighted than conventional photovoltaic devices due to their relatively low cost, easy fabrication and high efficiency. However, there are limitations to increase the conversion efficiency of DSCs. The limiting factors are the quantity of dye adsorption and charge recombination between TiO₂ electrode and electrolyte. Coating other materials such as high energy band gap insulators or semiconductors on the TiO₂ electrode enhances dye adsorption and reduces charge recombination. We fabricated DSCs based on bare TiO₂ nanotube arrays and 0.02 and 0.04 M MgO coated TiO₂ nanotube arrays. MgO layer increased the photovoltage and photocurrent. The overall conversion efficiency of DSCs using 0.02 M MgO coated TiO₂ nanotubes was 1.61%. MgO formed insulating layers between TiO₂ nanotube array electrode and electrolyte. Charge recombination was inhibited at the interfaces of TiO₂ nanotube array electrode and electrolyte by MgO insulating layers. MgO coating also improved dye adsorption because iso-electric point (IEP) of MgO was larger than TiO₂. When the IEP of coating material is larger than TiO₂, the chemical attraction between the electrode surface and Ru-based dye molecule is increased.     

A Comparative Study on the Photocatalytic Activity of Eucalyptus Leaf Assisted Green Synthesized ZnO and Chemically Synthesized ZnO towards the Degradation of Malachite Green Dye

Abstract

The photocatalytic activities of ZnO nanoparticles, synthesized by two methods, towards the degradation of Malachite green (MG) dye were studied and compared. Green synthesized ZnO nanoparticle was observed to be more effective in photodegradation and the effect of operating parameters such as catalyst loading, initial dye concentration and pH was investigated. Optimum condition was observed at catalyst load 0.24?g/L, initial dye concentration 20?ppm and pH nine which degrades 90% of the dye under 1?h of irradiation. X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX), UV-Vis spectroscopy and Fourier Transform Infrared spectroscopy(FTIR) were employed as characterization techniques for the samples.     

Laser-activated shape memory polymer microactuator for thrombus removal following ischemic stroke: preliminary in vitro analysis

Due to the narrow (3-h) treatment window for effective use of the thrombolytic drug recombinant tissue-type plasminogen activator (rt-PA), there is a need to develop alternative treatments for ischemic stroke. We are developing an intravascular device for mechanical thrombus removal using shape memory polymer (SMP). We propose to deliver the SMP microactuator in its secondary straight rod form (length=4 cm, diameter=350 /spl mu/m) through a catheter distal to the vascular occlusion. The microactuator, which is mounted on the end of an optical fiber, is then transformed into its primary corkscrew shape by laser heating (diode laser, /spl lambda/=800 nm) above its soft-phase glass transition temperature (T/sub gs/=55/spl deg/C). Once deployed, the microactuator is retracted, and the captured thrombus is removed to restore blood flow. The SMP is doped with indocyanine green (ICG) dye to increase absorption of the laser light. Successful deployment of the microactuator depends on the optical properties of the ICG-doped SMP, as well as the optical coupling efficiency of the interface between the optical fiber and the SMP. Spectrophotometry, thermal imaging, and computer simulation aided the initial design effort and continue to be useful tools for optimization of the dye concentration and laser power. Thermomechanical testing was performed to characterize the elastic modulus of the SMP. We have demonstrated laser activation of the SMP microactuator in air at room temperature, suggesting this concept is a promising therapeutic alternative to rt-PA.     

Visible Light Emission From Dye Molecular Grains via Infrared Excitation Based on the Nonadiabatic Transition Induced by the Optical Near Field

We observed light emission in the visible wavelength range (lambda = 600-690 nm) from aggregated 4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran (DCM) dye molecule grains excited by infrared light (lambda_ex = 805 nm). The domains of visible light emission were localized at the surface and edges of the dye grains, where the optical near field was strengthened. The emitted visible light intensity decayed exponentially according to the time constants tau₁ = 0.45 ns and tau² = 1.37 ns, which were equivalent to those of conventional fluorescence excited by visible light at lambda_ex = 402 nm. The emitted light intensity increased with the infrared excitation intensity, in agreement with the theoretical results of the exciton-phonon polariton model. This confirmed that the visible light emission originated from the nonadiabatic transition process due to optical near-field features. The frequency upconversion efficiency for excitation from infrared (lambda_ex = 805 nm) to visible (lambda = 600-690 nm) in the film of the DCM molecular grains was experimentally estimated to be higher than that of the second harmonic generation (SHG) from a potassium dihydrogen phosphate (KDP) crystal. In particular, it was higher when the fundamental light power density was lower than 100 W/cm². Visible light emission from the grains of the rhodamine 6G (N-{2-[2-(2-aminoethoxy)ethoxy]ethyl} rhodamine 6G-amide bis[trifluoroacetate]) dye molecule was also observed in the infrared light (lambda_ex = 805 nm). Our results demonstrated the universality of the nonadiabatic transition process.     

The nature of excited-state absorption in polymethine andsquarylium molecules

Subpicosecond transient absorption measurements were performed for several polymethine and squarylium dyes in ethanol solution and a polymeric host over the spectral range 400-1500 nm. A variety of nonlinear effects including saturable absorption, reverse saturable absorption, and gain were observed and analyzed. We observe strong excited-state absorption (ESA) in all dyes in the range 450-600 nm. We also report the first prediction and observation of additional ESA bands in the near-infrared range. The predictions were based on quantum chemical calculations and the ESA experiments were performed with femtosecond pump-continuum probe techniques. For polymethine dye 2-[2-[3-[(1,3-dihydro-3,3-dimethyl-1-phenyl-2H-indol-2-ylidene) ethylidene]-2-phenyl-1-cyclohexen-1-yl]ethenyl]-3,3-dimethyl-1-phenylindo lium perchorate, an additional ESA band was detected near 1250 nm, and for squarylium dye 1,3-Bis-[(1,3-dihydro-1-butyl-3,3-dimetyl-2H-benzo[e]indol-2-ylidene)meth yl]squ araine, two additional ESA bands were found around 870- and 1380-nm, respectively. To further study the nature of these transitions, the steady-state excitation anisotropy was also studied and compared with predictions. The relationship between ESA spectra of organic dyes and their molecular structure is discussed     

Development of a laser radar using LDS dye and sum frequency generation for NO2 measurement

A laser radar for measuring vertical concentration profiles of atmospheric NO₂ was developed. The laser transmitter uses an LDS765 dye laser pumped by a Nd:YAG laser. The dye laser output is converted to wavelengths 446.8 and 448.1 nm, which are used for NO₂ measurement, by sum frequency generation (SFG) using a pair of KD^*P crystals. The dependence of the LDS765 dye laser output on wavelength and dye concentration was investigated, and the performance of the laser transmitter was evaluated. Compared to the Coumarin 445 dye laser conventionally used for NO₂ measurement, this laser transmitter represents a significant improvement in output stability, as well as in maximum output energy and overall conversion efficiency. Using the newly developed laser radar, NO₂ concentrations of 20 to 40 ppb were measured for vertical range 500 to 1000 m, which were in rough agreement with values monitored on the ground. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(2): 26–33, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10231     

Decrease in ac partial discharges on insulating materials by use ofdye additives

The purpose of this study is to decrease PD at a triple junction by addition of a dye to an insulating material. PD is produced on a test specimen subjected to ac voltage under a sphere-plane electrode configuration. The specimen is composed of two layers: a PMMA film with additive, which is 100 μm thick; the lower layer a PMMA board 3 mm thick. The film with the additive was prepared by the solution-grown casting method. Five kinds of dye were used as the additive; p-aminoazobenzene (Ab), p-nitrobenzeneazoresorcinol (Nb), methyl yellow (My), methylene blue (Mb) and methyl red (Mr). In the case of the films with Ab and Mb at 0.05% wt, the magnitude and number of PD pulses were reduced to ~50% less than those in the case of the films without the additive. The decrease in PD was effective under an electric field strength slightly higher than the PD inception. In the case of the other dyes, decrease in PD was not observed. The surface voltage distribution due to the charge by PD depended on the kind of dye additive. The decrease in PD for the Ab and Mb films was explained from the dependence of the surface voltage distribution on the dye. It was concluded that ionization of the dye molecules in the film changes the distribution of surface voltage     

Mechanism of dye-enhanced pulsed laser ablation of hard tissues:implications for dentistry

Alexandrite laser ablation of enamel enhanced by an indocyanine green dye was studied. A microjet system was employed to deliver precisely measured small amounts of absorbing dye solution to the site of irradiation. A sequence of physical phenomena involved in dye-enhanced laser ablation of dental enamel was revealed when laser pulse profiles were compared with the profiles of laser-induced pressure, laser-induced plasma, and ablation plume kinetics. To understand photomechanical effects on the enamel ablation, the absolute values of pressure waves were measured by a calibrated wide-band acoustic transducer. Absolute amplitude and temporal profile of pressure waves, plasma emission, ablation plume kinetics, ablation efficiency, and crater quality under free-running and and Q-switched ablation of enamel were studied. It was found that there is an optimal dye solution volume (100-200 nL) when the maximum ablation efficiency (30 μm/pulse) can be obtained. It was shown that the ablation efficiency under Q-switched laser irradiation is approximately one order of magnitude lower than that under free-running ablation. It was shown that Q-switched enamel ablation with dye solution is caused by the powerful recoil pressure wave with an amplitude 3-6.5 kbar. In contrast, dye-enhanced free-running enamel ablation is caused by plasma-mediated evaporation of enamel and accompanied by recoil pressure waves of lower amplitude (0.5-1 kbar) that is below mechanical damage threshold in enamel. Uneven crater walls after Q-switched ablation were observed by scanning electron microscopy (SEM). Free-running ablation makes precise craters with smooth and even crater walls     

用气相沿面放电生成臭氧方式降解偶氮染料废水的影响因素分析

为提高臭氧降解和脱色染料废水的效果,通过沿面放电臭氧生成-废水处理一体化反应器降解偶氮染料废水研究了供电电源类型、放电电压、放电反应器内注入的气体组分及流量、废水电导率、催化剂等因素对染料降解的影响。研究结果表明:同50Hz工频电源相比,在相同的输入功率下,高频电源降解偶氮染料效果更快;沿面放电反应器内注入的气体成分影响染料降解率,注入氧气时,甲基红降解率最高,注入氮气时,甲基红几乎没有降解;注入气体流量影响气相和液相臭氧浓度及染料废水的湍流度,进而影响甲基红的降解率;废水电导率对甲基红降解影响不大;二氧化钛添加量影响甲基红的降解,染料降解初期,适量的二氧化钛有利于甲基红的降解。     

双极性脉冲放电等离子体处理染料废水时化学需氧量去除效果相关因素分析

在双极性脉冲放电等离子体用于染料废水的降解过程中,废水化学需氧量(chemical oxygen demand,COD)的变化是在更深层次上反映该技术对有机污染物的降解能力的重要指标。为此,重点研究了在气液固三相混合体双极性脉冲放电条件下典型染料废水COD的去除规律,测试了不同电压、气体流量、初始浓度等条件下染料废水COD的变化。实验结果表明:当负载电压较高时,染料废水的COD值会先升高然后不断降低;而负载电压较低时,COD值会在一定程度内缓慢上升;气体流量越高,COD的去除效果越好;废水初始浓度增加,COD的去除率略有下降;初始电导率增加,COD的去除率降低;对具有不同官能团的染料废水进行放电处理发现,双极性脉冲放电对于各种结构的染料均有良好的处理效果。     

染料敏化分解水制氢技术进展

介绍了染料敏化分解水制氢的基本原理。综述了染料分子的选取,使用氧化还原调节剂的机理和研究进展。指出染料分子对光谱的吸收特性,激发态染料分子能级与半导体导带的相对位置,染料分子与半导体的吸附情况,表面键合强度直接影响对光子的吸收,电子的注入,从而影响产氢量。此外,I-/I3-作为氧化还原调节剂可有效还原染料分子,实现持续产氢。最后提出了染料敏化分解水制氢的间歇式反应器结构,以及通过选择用于敏化的半导体来提高产氢率的思路。     

Electroluminescence color tuning by dye doping in organiclight-emitting diodes

Doping a small amount of a fluorescent dye into an organic light-emitting diodes (OLEDs) can lead to significant changes in the color of luminescence and an improvement in the device properties (e.g,, quantum efficiency, lifetime, etc.). The process of energy transfer from the OLED material to the dye in these devices may involve several different processes, including carrier trapping as well as Forster and Dexter energy transfer reactions. The important parameters for each of these processes are discussed. The color purity and chromaticities of a wide range of different dye-doped OLED's are reviewed     

The Ionization Potential of Carrier Transport Materials in Relation to the Photosensitivity of Double Layered Photoreceptors

Double layered photoreceptors using low ionization potential molecules as the carrier transport layer (CTL) have been investigated. The ionization potential (lp) was estimated by the ? technique calculation and the polarographic oxidation potential. A good correlation was obtained between the photosensitivity and the lp value of the CTL. However this result could not be explained simply by the energy level misfit of the carrier generation layer (CGL) and the CTL. Styryl dye bases, cyanine dye bases, and oxazoles were selected as CTL materials on the basis of their transparency and high solubility in polymers. The photoreceptors using these CTL materials showed much higher sensitivities than the well-known polyvinylcarbazole- trinitrofluorenone (PVK-TNF) system. The peak value of the spectral sensitivity in the system composed of an oxazole, OX-2, and a disazo pigment, chlorodianeblue (CDB), was 0.17 m 2/mJ at 650 nm.     

太阳能电池中纳米TiO2多孔膜的制备

纳米TiO2多孔膜具有非常大的比表面积，其表面上吸附大量的染料分子进行敏化以后可以有效地吸收太阳光，并将其转化为电能。本介绍了染料敏化的纳米TiO2太阳能电池的基本结构和工作原理，以及染料敏化的纳米TiO2多孔膜的制备及研究现状。     

固态电解质对染料敏化太阳电池性能的影响

由于染料敏化太阳电池(简称DSCs)的光电转换效率高、制作的成本较低且工艺较简单等特点,被认为是薄膜太阳电池中最具市场潜力的新型电池之一。固态电解质在染料敏化太阳电池中起着运输载流子、还原染料等实现电池内部循环的作用。由于效率较高的液态电解质具有易泄露和挥发等特点,会影响电池的寿命和稳定性,所以制备性能较好的固态电解质对电池的产业化及实用化有重要意义,也是DSCs电池发展的必然趋势。论述了DSCs电池的基本工作原理及结构组成、发展现状及趋势,并结合相关工作介绍固态电解质对其寿命及稳定性的影响。     

Preliminary Investigation of Prebreakdown Phenomena and Chemical Reactions Using a Pulsed High-Voltage Discharge in Water

Prebreakdown phenomena in water were investigated for point-plane geometries using high-voltage pulses. Spot discharges, filamentary magenta streamers, isolated microdischarges, and microbubbles were observed and photographed. Emission spectra were obtained using a prism spectrograph. Maximum streamer lengths were determined as a function of applied voltage, pulsewidth (decay constant), and water conductivity. The bubbling of gas through the underwater discharge resulted in the disintegration of the gas bubbles, and also caused gas-phase discharges to occur near the nozzle electrode. The production of 03, accomplished by bubbling O2 gas through a discharge in deionized water, was investigated using a colorimetric indigo dye test that measured the concentration of 03 in the water. Chemical reactions occurring when 02 or N2 gas was bubbled through a discharge in an anthraquinone dye solution were studied by photometrically measuring the decolorization of the dye.     

汽轮机轴向装配枞树型叶根检测方法

采用渗透、超声表面波、磁粉等检测方法对某台汽轮机轴向装配枞树型叶根进行检测,并对以上3种方法进行了比较。结果表明,磁粉检测的磁痕部位缺陷与超声表面波检测的结果完全一致,即在叶根出汽侧第1齿存在长15mm的未开口裂纹。由于磁粉检测不易操作,建议汽轮机轴向装配枞树型叶根的检验方法以超声表面波检测为主,磁粉检测和渗透检测共同验证和配合。     

Multiscale modeling in rodent ventricular myocytes

This paper indicates that in ventricular myocytes when the SR (sarcoplasmic reticulum) is pharmacologically inhibited, the intracellular Ca²⁺concentration rapidly increases during Ca²⁺ entrance (0-70 ms), whereas the decay of Ca²⁺ is slow; in the absence of fluorescent dye, large Ca²⁺ concentration gradients might develop near the cell membrane; intracellular Ca²⁺ distribution is tightly regulated by the localization of Ca²⁺transporter proteins along the sarcolemma and strongly relays on the presence of mobile and stationary Ca²⁺ buffers. These studies also imply that in ventricular cells with intact and functional SR, the Ca²⁺ signal most likely would spread faster along the t-tubular system, surface membrane than to the cell interior and that in the absence of Ca²⁺ dye high Ca²⁺ gradients under the surface membrane and more uniform Ca²⁺ distribution in the cell interior might be expected.     

钌配合物在染料敏化太阳电池中的应用

基于钌配合物具有丰富的光电化学特性和高的光电转换效率,目前已被作为染料敏化纳米晶太阳电池的高效敏化剂.概述了近年来国内外对钌配合物电化学性质的研究,综述了配体结构和配合物本身结构对钌配合物基本电化学性质的影响,介绍了目前钌配合物在染料敏化太阳电池中的应用,提出了今后的研究方向.