Positive Schatten(-Herz) Class Toeplitz Operators on the Half-space

On the harmonic Bergman space of the half-space, we give characterizations for an arbitrary positive Toeplitz operator to be a Schatten (or Schatten-Herz) class operator in terms of averaging functions and Berezin transforms. Examples are provided to show that various results are sharp. This research was supported by KOSEF(R01-2003-000-10243-0).     

Luminescence enhancement of Eu-doped calcium magnesium silicate blue phosphor for UV-LED application

(Ca_1−x,Eu_x)MgSi_2yO_6+δ blue phosphor was prepared by spray pyrolysis and the photoluminescence properties were optimized by controlling concentration of Si element and the activator content. At y=1.0, the concentration quenching in the luminescent intensity appeared when the Eu²⁺ content (x) was 0.01 (1 at%). Such quenching concentration was changed with the concentration of silicon (y), which was increased with an increase in the quantity of excess Si (y>1.0). The highest luminescent intensity was achieved when the Eu²⁺ content (x) and the Si concentration (y) were 0.04 and 1.3, respectively. According to X-ray diffraction (XRD) analysis, the tetragonal SiO₂ phase was formed as a minor phase when the y value was larger than 1.3. The formation of SiO₂ phase, however, did not reduce but increased the luminescent intensity when the Eu²⁺ content was optimized again. As a result, the luminescent intensity of the phosphor particles optimized in the content of both Si and Eu²⁺ was about 150% improved compared with that of the CaMgSi₂O₆:Eu sample (x=0.01, y=1.0).     

Misalignment tolerance analysis and fabrication for highly efficient parallel optical-electrical convertor module

A compact, highly efficient, and passively assembled parallel optical-electrical convertor module (POECM) for active optical cable application is proposed. This paper presents our POECM structure, optical design simulation results, fabrication process, and data transmission test results, in sequence. The POECM has a compact size of \(18.5\hbox {mm} \times 10\hbox {mm} \times 2.8\hbox {mm}\) . We confirm a data rate of total throughput at 21.6 Gbps ( \(5.4\hbox {Gbps} \times 4\) channels) with a bit error rate of less than \(10^{-12}\) .     

二极管阵列紫外分光光度法测定西埃斯

利用紫外分光光度法对西埃斯进行检测,在0.2072-10.36μg/mL浓度范围内线性关系良好(R2=0.9990),检出限为0.0518μg/mL,相对标准偏差(RSD)为0.82％,回收率在99.3％-100.1％之间.本法操作简便,准确,能较好的应用于气溶胶中痕量西埃斯的测定.     

Influence of TiO2 nanotube morphology and TiCl4 treatment on the charge transfer in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) were fabricated using TiO₂ nanoparticles (NPs), TiO₂ nanotube arrays (NTAs), and surface-modified NTAs with a TiCl₄ treatment. The photovoltaic efficiencies of the DSSCs using TiO₂ NP, NTA, and TiCl₄-treated NTA electrodes are 4.25, 4.74, and 7.47 %, respectively. The highest performance was observed with a TiCl₄-treated TiO₂ NTA photoanode, although in the case of the latter two electrodes, the amounts of N719 dye adsorbed were similar and 68 % of that of the NP electrode. Electrochemical impedance measurements show that the overall resistance, including the charge–transfer resistance, was smaller with NTA morphologies than with NP morphologies. We suggest that a different electron transfer mechanism along the one-dimensional nanostructure of the TiO₂ NTAs contributes to the smaller charge–transfer resistance, resulting in a higher short circuit current (J _sc), even at lower dye adsorption. Furthermore, the TiCl₄-treated NTAs showed even smaller charge–transfer resistance, resulting in the highest J _sc value, because the downward shift in the conduction band edge improves the electron injection efficiency from the excited dye into the TiCl₄-treated TiO₂ electrodes.     

The Smart 2-(2-Fluorobenzoyl)-N-(2-Methoxyphenyl)Hydrazinecarbothioamide Functionalized as Ni(II) Sensor in Micromolar Concentration Level and its Application in Live Cell Imaging

In recent years, fluorescent probes for the detection of environmentally and biologically important metal cations have received extensive attention for designing and development of fluorescent chemosensors. Herein, we report the photophysical results of 2-(2-fluorobenzoyl)-N-(2-methoxyphenyl) hydrazinecarbothioamide (4) functionalized as Ni (II) sensor in micromolar concentration level. Through fluorescence titration at 488 nm, we were confirmed that ligand 4 showed the remarkable emission by complexation between 4 and Ni (II) while it appeared no emission in case of the competitive ions (Cr³⁺, Fe²⁺, Co²⁺, Ba²⁺, Cu²⁺, Ca²⁺, Na⁺, K⁺, Cu⁺, Cs⁺). Furthermore, ligand 4 exhibited no toxicity with precise cell permeability toward normal living cells using L929 cell lines in bio imaging experiment investigated through confocal fluorescence microscope. The non-toxic behavior of ligand 4 (assessed by MTT assay) and its ability to track the Ni²⁺ in living cells suggest its possibility to use in biological system as nickel sensor.

FDTD Simulation of Electromagnetic Pulse Interaction with a Switched Plasma Slab

This paper deals with the Finite Difference Time Domain (FDTD) simulation of interaction of an electromagnetic wave with a switched plasma slab. In formulating the simulation the well-known concepts of (a) total-field/scattered-field formulation (b) and PML lattice truncation are adapted to suit the simulation under consideration.FDTD is particularly well suited to handle the switched (time-varying) medium (including sudden switching) since the time varying parameters of the medium can be easily interpreted in the algorithm. The technique is applied to the difficult problem of interaction of an electromagnetic pulse source wave of frequency ₀ and a gaussian envelope with a newly created plasma slab of time-varying and space varying electron density profile. The creation of a pulse of Wiggler magnetic field in the slab is illustrated.     

Photonic Crystal Fiber Attenuator

We propose a novel fiber attenuator based on photonic crystal fibers. The difference in the modal field diameters of a conventional single mode fiber and a photonic crystal fiber was used. A variable optical attenuator was also achieved by applying macro-bending on the PCF part of the proposed attenuator     

Ordered space-time structures: Quantum carpets from Gaussian sum theory

The term "quantum carpet" can be observed in many closed quantum systems, where the evolution of a wave function exhibits a carpet-like pattern. Quantum carpet mechanisms are also akin to the classical interference patterns of light. Although the origins of quantum carpets have previously been studied by various researchers, many interesting details are still worth exploring. In this study, we present a unified framework for simultaneously analyzing three different features of quantum carpets: full revival,fractional revival, and diagonal canal. For the fractional revival feature, a complete formula is presented to explain its formation through Gaussian sum theory, in which all essential features, including phases and amplitudes, are captured analytically. We also reveal important relationships between the interference terms of diagonal canals and their geometric interpretations such that a better understanding of the development of diagonal canals can be supported.