空穴注入层技术在聚合体OLED器件中的重要性

空穴注入层技术可降低OLED成本和提高其生产效率,是使柔性OLED显示成为商品化的一个重要因素。     

An analytical model for a TFET with an n-doped channel operating in accumulation and inversion modes

The tunnel field-effect transistor (TFET) is an ambipolar device that conducts current with the channel in both accumulation and inversion modes. Analytical expressions for the channel potential and current in a TFET with an n-doped channel when operating in the accumulation and inversion modes are proposed herein. The potential model is derived by solving the two-dimensional (2D) Poisson equation using the superposition principle while considering the charges present in the channel due to electron or hole accumulation along with the depletion charges. An expression for the tunneling current corresponding to the maximum tunneling probability is also derived. The tunneling current is obtained by analytically calculating the minimum tunneling length in a TFET when operating in the accumulation or inversion mode. The results of the proposed potential model is compared with technology computer-aided design (TCAD) simulations for TFET with various dimensions, revealing good agreement. The potential and current in an n-type TFET (nTFET) obtained using the proposed models are also analyzed.

     

Dynamic Scheduling and Fault-Tolerance: Specification and Verification

Considera distributed real-time program which is executed on a systemwith a limited set of hardware resources. Assume the programis required to satisfy some timing constraints, despite the occurrenceof anticipated hardware failures. For efficient use of resources,scheduling decisions must be taken at run-time, considering deadlines,the load and hardware failures. The paper demonstrates how toreason about such dynamically scheduled programs in the frameworkof a timed process algebra and modal logic. The algebra providesa uniform process encoding of programs, hardware and schedulers,with an operational semantics of a process depending on the assumptionsabout faults. The logic specifies the timing properties of aprocess and verifies them via this fault-affected semantics,establishing fault-tolerance. The approach lends itself to applicationof existing tools and results supporting reasoning in processalgebras and modal logics.     

A multi-balanced hybrid optimization technique to track objects using rough set theory

In this paper, the process of object detection and tracking is performed by means of five stages, namely frame segregation, shot segmentation, shape and texture feature extraction, object detection in frames through rough set theory and soft computing evolutionary programming with hybrid genetic algorithm particle swarm optimization. In the first stage, the input video file is segregated into number of frames and then the image frame from the specific shots is alone separated in the second stage with the help of DCT transformations. The third phase involves extracting shape and texture features from the shot segmented image frames.     

Observation of Spin-Glass Behavior in La0.85Sr0.15CoO3 Single Crystals

The magnetic behavior of La_0.85Sr_0.15CoO₃ single crystals and polycrystals has been subjected to a controversial debate for the last several years; while some groups show evidence for phase separation, others show spin-glass (SG) behavior. Here, we present a comprehensive investigation of the structural, ac susceptibility, and dc magnetization properties of La_0.85Sr_0.15CoO₃ single crystals grown by float zone method. The structural analysis of XRD data by Rietveld refinement reveals the single crystallographic phase. The ac susceptibility results exhibit a frequency dependent peak shift (??2 K) and time-dependent memory effect below the freezing temperature. The characteristic time scale ?? _o calculated from this peak shift is found to be of ??10^?13 s which matches very well with typical values observed for a SG system. Further, the peak shift of the zero-field-cooling curves to lower temperature at higher dc fields is well described by the well-known de Almeida Thouless line, a characteristic of SG behavior. Thus, all our experimental findings confirm the existence of SG behavior in La_0.85Sr_0.15CoO₃ single crystals.     

Dislocation, annealing and quenching effects on the microindentation hardness of Bi2Te3 and Bi2Te2.9Se.1 single crystals

Stoichiometric crystals of Bi₂Te₃ and Bi₂Te_2.9Se_.1 have been grown from the melt by the horizontal zone melting (HZM) technique. X-ray powder diffraction and energy dispersive X-ray analysis could prove that the grown crystals are stoichiometric with lattice constants a=0.4374 nm, c=3.044 nm for Bi₂Te₃ and a=0.4374 nm, c=3.038 nm for Bi₂Te_2.9Se_.1. Dislocation density measurements are carried out by etch pit technique and are observed by scanning electron and optical micrograph. The mechanical strength of the as-grown, quenched and annealed crystals is assessed by the Vickers hardness measurements.     

Photocatalytic degradation of phosphamidon on semiconductor oxides

The photocatalytic degradation of a small concentration of an organo-phosphorous (OP) insecticide phosphamidon, in water, on ZnO and TiO(2) is investigated. Of the two semiconductor oxides, TiO(2) is found to be more effective as a photocatalyst for this reaction. Several factors such as concentration of phosphamidon, pH of the system, catalyst loading and presence of anions are found to influence the degradation rate. The reaction follows apparent first-order kinetics, though at higher concentrations, there is a reduction in the order of the reaction. There is a simultaneous formation and decomposition of H(2)O(2) in the system, resulting in a periodic increase and decrease in its concentration. The catalyst TiO(2) is effective for the degradation of phosphamidon in direct sunlight and thus opens the possibility of solar decontamination of wastewater containing small amounts of OP pesticides.     

Studies on lithium l-ascorbate dihydrate: An interesting chiral nonlinear optical crystal

Lithium l-Ascorbate dihydrate (LLA) is a new metal organic nonlinear optical crystal belonging to the saccharide family. Single crystals of LLA were grown from aqueous solution. Solubility of the crystal has a positive temperature coefficient facilitating growth by slow cooling. Rietveld refinement was used to confirm the phase formation. The crystal has prismatic habit with (010), (001) and (10−1) prominent faces. Thermal analysis shows that the crystal is stable up to 102 °C. Transmission spectrum of the crystal extends from 302 nm to 1600 nm. Dielectric spectroscopic analysis revealed Cole–Cole behaviour and prominent piezoelectric resonance peaks were observed in the range of 100–200 kHz. Second harmonic generation (SHG) conversion efficiency of up to 2.56 times that of a phase matched KDP crystal was achieved when the (010) plate of LLA single crystal was rotated about the +ve c axis, by 9.4° in the clockwise direction. We also observed SHG conical sections which were attributed to noncollinear phase matching. The observation of the third conical section suggests very high birefringence and large nonlinear coefficients. A detailed study of surface laser damage showed that the crystal has high multiple damage thresholds of 9.7 GW cm⁻² and 4.2 GW cm⁻² at 1064 nm and 532 nm radiation respectively.     

In vitro studies on antioxidant activity of lignans isolated from sesame cake extract

The antioxidant activity of compounds isolated from a methanolic extract of commercial sesame cake was studied using a peroxidation model and a radical‐scavenging method. Pure compounds were isolated from the extract by preparative high‐performance liquid chromatography (HPLC) and identified and confirmed as sesamol, sesamin, sesamolin, sesaminol diglucoside and sesaminol triglucoside by HPLC, infrared, nuclear magnetic resonance and mass spectrometry. When the rate of inhibition of lipid peroxidation and the superoxide radical‐scavenging power of the individual compounds were evaluated, the compounds showed antioxidant activity to different extents. The antioxidant activity of compounds by the β‐carotene‐bleaching assay followed the order sesamol > sesamolin ≥ sesamin > butylated hydroxytoluene (BHT) > sesaminol triglucoside > sesaminol diglucoside. By the thiocyanate method the inhibition of linoleic acid peroxidation shown by sesamol, sesamin, sesamolin, sesaminol triglucoside, sesaminol diglucoside and BHT at 200 mg l^?1 was 77, 60, 69, 32, 25 and 49% respectively. A concentration–dependent superoxide–scavenging effect was also shown by these compounds. Sesamolin had an appreciable effect at 300 and 500 mg l^?1, while the other compounds were more effective at 100 mg l^?1. The study also established the occurrence of sesamol in the methanolic extract of defatted sesame cake for the first time. Copyright © 2005 Society of Chemical Industry     

Quality evaluation of the ‘agmark’ grades of cardamom Elettaria cardamomum

Eighteen export grades (Agmark) of Indian cardamom have been studied for their chemical and physical qualities. The grades with heavier and bigger capsules (AGEB and CGEB) were inferior in their flavour constituents to the medium grade (AGS). Chemical bleaching of the capsules decreased the amount of flavour components, especially essential oil, in the capsules.