Precursor-dependent structural diversity in luminescent carbonized polymer dots (CPDs): the nomenclature

Carbon dots (CDs) have received immense attention in the last decade because they are easy-to-prepare, nontoxic, and tailorable carbon-based fluorescent nanomat...     

Electromagnetic emission based monitoring technique for polymer ZnO surge arresters

Electromagnetic emission at the very high frequency (VHF) range of 30 to 300 MHz is used to detect surface defects on outdoor polymer zinc oxide (ZnO) surge arresters. The partial discharge related signals are recorded and studied. Since the surge arresters are usually exposed to adverse weather conditions, the effect of moisture and pollution on the characteristics is also investigated. Samples subjected to surface pollution were created according to the IEC standard under both wet and dry conditions. The collected electromagnetic signals were sampled and analyzed using a joint time-frequency analysis tool called the Wigner-Ville distribution (WVD). The results of this work indicate that the WVD analysis can be used as a diagnostic tool for polymer ZnO surge arresters.     

聚合物锂离子电池用强化电解质隔膜的研制

研制了一种聚合物锂离子电池用的强化电解质隔膜,该强化电解质隔膜采用聚丙烯/聚乙烯/聚丙烯(PP/PE/PP)三层复合微孔隔膜为基体,通过对基体进行表面处理得到.研制的强化电解质隔膜在保持较高强度的同时,具有较好的吸液性和保液性,室温下电导率可达3.38×10-4S/cm,用该隔膜装配的电池体积减小,成品率提高,电池性能与采用聚合物电解质的电池性能相似.     

碳酸钙晶须对聚合物流变性能的影响

碳酸钙（CaCO3)晶须是一种新型的一维晶体材料，作为填料可以对聚合物起到增强和增韧的作用。论文研究比较了碳酸钙晶须，钛酸钾晶须，轻质碳酸钙三种不同填料对聚合物（PP，PVC以及HDPE）复合体系的流变性能影响，结果表明用两种晶须材料对流变性能的影响明显优于填充轻质碳酸钙的体系，而且CaCO3晶须成本比钛酸钾晶须低廉，具有更广阔的市场前景。     

Observation of the electrorheological effect of siliconeoil/polymer particles suspension

A liquid insulator that suspends small particles is one of the electrorheological fluids (ERF) whose apparent viscosity becomes larger under an electric field because of the formation of particle chains. Since many possible applications of ERF are expected, the development of a more practical ERF is required. We have investigated the ER effect of silicone oil in which small particles are suspended. Silica particles, silica particles coated by conductive polymer film, and polymer particles (microcrystalline cellulose), with a diameter between 5~100 μm, are investigated in order to clarify the difference between suspending materials. To measure the ER effect, a rotational viscometer was constructed. It became clear that the shear stress for cellulose particles is much stronger than that for other particles because of its peculiar particle chain formation due to the particle shape     

Effect of quantum dots on InAs/GaAs p-i-p quantum dots infrared photodetectors

ABSTRACT

In this paper, the InAs/GaAs p-i-p quantum dots infrared photodetectors (QDIPs) were successfully demonstrated by Apsys software. It consists of Al_0.3Ga_0.7As/GaAs structure to reduce dark current and InAs quantum dots (QDs) embedded in In_0.15Ga_0.85As as an active layer. The effect of structure parameters of InAs QDs on the dark current, photocurrent of the device and SNR (signal to noise) is discussed respectively, including different QDs density, the number of QD layer, GaAs thickness between QDs layers and Al_0.3Ga_0.7As, and GaAs thickness between two the QD layers.     

加强电力需求侧管理促进节能减排取得新成效

中国政府高度重视资源节约和环境保护,特别是2006年以来,进一步加大了工作力度,着力推进经济结构调整,依法淘汰落后产能,抑制高耗能高污染行业过快增长,全面实施低效燃煤工业锅炉改造、区域热电联产、余热余压利用等十大     

Light amplified oxidative stress in tumor microenvironment by carbonized hemin nanoparticles for boosting photodynamic anticancer therapy

Photodynamic therapy (PDT), which utilizes light excite photosensitizers (PSs) to generate reactive oxygen species (ROS) and consequently ablate cancer cells or...     

聚合物锂离子电池凝胶聚合物电解质的进展

报道了聚合物锂离子电池用凝胶聚合物电解质(GPE)的进展,对PEO、PAN、PMMA和PVDF基GPE的研究现状、改良方法和发展方向进行了综述.     

Phonon bottleneck effects in rectangular graphene quantum dots

For a graphene sheet with confining structures in the orthogonal directions of zigzag- and armchair-edge, the confined carrier states are determined. These wavefunctions and eigenvalues are used to study carrier-longitudinal optical (LO)-phonon interactions in these graphene quantum dots. The optical deformation potential is derived for these graphene quantum dots as the basis for the study of these carrier-LO-phonon interactions. Phonon bottleneck effects are identified and the Fermi golden rule transition rates are formulated.     

Progress in GaN-based quantum dots for optoelectronics applications

Our recent progress in GaN-based quantum dots (QDs) for optoelectronics application is discussed. First, we discussed an impact of the use of GaN-based QDs on semiconductor lasers, showing theoretically that reduction of threshold current by using the QDs in GaN-based lasers is much more effective compared to those in GaAs-based or InP-based lasers. Then discussed are our growth technology including self-assembling growth of InGaN QDs on sapphire substrates by atmospheric-pressure metalorganic chemical vapor deposition. Using the self-assembling growth technique, we have succeeded in obtaining lasing action in an edge-emitting laser structure with the InGaN QDs embedded in the active layer under optical excitation with the emission wavelength of 410 nm. Toward UV light wavelength emission, we have recently established self-assembled GaN QDs of high quality and high density under very low V-III ratio. We clearly observed two photoluminescence peaks from both the QDs and the wetting layer at room temperature, which clearly shows the nanostructures are formed with the Stranski-Krastanow growth mode.     

Lateral carrier confinement in miniature lasers using quantum dots

Although quantum-dot (QD) lasers are yet to reach their promise of ultralow threshold and high characteristic temperature because of QD size nonuniformity, we have found that they can be used to effectively limit the lateral diffusion of carriers in the active region, enabling the scaling of lasers to small lateral dimensions. Although oxide apertures continue to enable improved performance in vertical-cavity surface-emitting lasers (VCSEL's) by reducing optical losses and current spreading, lateral carrier losses remain uncontrolled. We investigate QD active material in which lateral diffusion is intentionally reduced. Cathodoluminescence (CL) results demonstrate reduced lateral diffusion in the material with which we expect 50% reduction in the threshold current for 1-μm-wide edge-emitters or 5-μm-diameter VCSEL's. We have made QD stripe lasers with submicrometer widths that lase from the ground state and have quantified the lateral carrier reduction in the QD laser active region. We show empirically that the degree of lateral carrier confinement is dependent on the quantum state from which lasing occurs and demonstrate 63% reduction in lateral carrier leakage for the ground-state lasers. Finally, the scaling of threshold current in QD VCSEL's is compared with that of quantum-well (QW) VCSEL's by numerical modeling for future design considerations     

Space charge behavior in an antistatic polymer including polymer solid electrolyte

A polymer dielectric material tends to be easily charged and may cause an electrostatic discharge, due to the serious problems that result when consequent electromagnetic noise damages the electronic circuits in various kinds of apparatus. The antistatic polymers that have been developed to prevent electrostatic discharge contain polymer solid electrolytes so that space charge originally exists inside them. The mechanism of the antistatic discharge effect of the polymer has been investigated by measuring the space charge distribution using the high-resolution pulsed-electroacoustic method. The experimental results suggest that the internal space charge of the polymer accumulates at the surface and forms heterocharge distribution at the interface between the electrodes and the specimen. Thus, internal space charge compensates the applied electric field, resulting in preventing the increase of the surface potential. In addition, internal space charge behavior relates to the dispersion condition of the polymer solid electrolyte that depends on the quantity of the electrolytes and the specimen procedures.     

碳交易政策电力碳减排空间溢出效应研究

电力是我国碳排放量最高的行业,也是全国碳市场的交易主体,推动电力行业低碳发展是中国实现“双碳”目标的重要抓手。基于2005—2019年我国30个省份电力行业面板数据,考虑电力碳强度的空间相关性,构建空间双重差分模型分析碳交易政策对电力行业碳强度的影响,检验碳交易政策的空间溢出效应;在此基础上,进一步构建中介效应模型分析碳交易政策的影响机制。研究发现：碳交易政策能够显著降低电力行业碳强度,并且这种抑制作用逐年增强,政策对碳强度的减排效果比碳排放总量更好;电力行业碳强度具有显著的空间正相关性,试点地区实施碳交易政策能够形成政策溢出效应,推动相邻地区碳减排;碳交易政策主要通过调整能源消费结构、降低电耗强度和促进产业结构升级来降低电力碳强度。基于上述结论,提出了相关政策建议。     

Classical and quantum mechanical transport simulations in open quantum dots

Simulations of open dot arrays are performed where the electron motion is considered in a harmonic potential and in a static magnetic field. Results concern electron trajectories and Poincaré sections from the classical calculation. The analysis of the Poincaré sections reveals a strong influence of the length of the constriction on the chaotic regions in phase space. Density probabilities from the quantum mechanical calculation show a significant correspondence to classically calculated trajectories.     

Influence of aging effect on behavior of field emission sites in a broad‐area vacuum gap

In order to discuss the characteristics of field emission sites, an aging effect on field emission current was measured in terms of cathodes subjected to two different surface treatments: mechanical polishing and thin film formation. A field was applied to the test cathodes up to an emission current of 10^–11A. Such measurement was repeated 50 times. It was found that the field emission current decreased with increasing number of test runs, and the amount of such degradation was larger for the case of mechanical polishing than for thin film formation. The field enhancement factor β evaluated by F–N plot was kept constant with increasing test runs for the mechanical polishing, while β increased with increasing test runs for the thin film formation. It was estimated by means of emission site observation that the emission sites on the mechanically polished cathode were related to the adsorption gases or weakly attached foreign particles, while the emission sites on the thin film formation cathode were related to the metallic whiskers. The characteristics of emission sites could be controlled by the surface treatment, especially by the thin film formation. © 2001 Scripta Technica, Electr Eng Jpn, 136(3): 10–18, 2001     

Exciton dephasing and absorption line shape in semiconductor quantum dots

The homogeneous broadening of exciton absorption spectral lines in semiconductor quantum dots (QDs) in the strong confinement regime is studied theoretically. It is shown that the term linear in nuclear displacements in the difference of the phonon Hamiltonians of the ground and optically excited states does not lead to the zero-phonon line (ZPL) broadening. The ZPL width is contributed by the term quadratic in nuclear displacements associated with short-living optical phonons. This contribution is estimated for CdSe nanocrystals (NCs) and found to be much less than the linewidth observed in recent experiments. We conclude that the experimentally observed linewidth is due to the longitudinal lifetime associated with the exciton relaxation to the dark state. The shape of spectral wings originating from the exciton interaction with long-living acoustic phonons is studied at various temperatures for a CdSe NC embedded in a glass matrix.     

聚合物锂离子蓄电池室温固体电解质的研制

选用聚乙烯醇缩丁醛 (PVB)作主体高分子 ,以LiClO4为碱金属盐 ,加入PC增塑剂 ,制备了聚合物电解质。该方法简单实用 ,得到的膜为无定形高分子。当n(PVB)∶n(LiClO4)∶n(PC) =5∶1∶3(摩尔比 )时 ,电导率为 7.8× 10 - 4 S·cm- 1 。运用XRD、DSC、交流阻抗等测试手段 ,对影响聚合物电导率的因素作了初步探讨。电导率随着锂盐浓度的增加 ,呈现先增后减的趋势 ,当n(PVB)∶n(LiClO4) =5∶1时 ,电导率达到最大值。电导率同时也受到增塑剂的影响 ,当n(增塑剂 )∶n(锂盐 ) =3∶1时 ,电导率较高。电导率与温度的关系符合Arrhenius公式 ,聚合物电解质的活化能为 59.4kJ/mol     

Advances in polymer integrated optics

We report on advances in polymeric waveguide technologies developed worldwide for the telecom and datacom markets, and we describe in detail one such technology developed at AlliedSignal. Optical polymers are versatile materials that can be readily formed into planar single-mode, multimode, and microoptical waveguide structures ranging in dimensions from under a micrometer to several hundred micrometers. These materials can be thermoplastics, thermosets, or photopolymers, and the starting formulations are typically either polymers or oligomers in solution or liquid monomers. Transmission losses in polymers can be minimized, typically by halogenation, with state-of-the-art loss values being about 0.01 dB/cm at 840 nm and about 0.1 dB/cm at 1550 nm. A number of polymers have been shown to exhibit excellent environmental stability and have demonstrated capability in a variety of demanding applications. Waveguides can be formed by direct photolithography, reactive ion etching, laser ablation, molding, or embossing. Well-developed adhesion schemes permit the use of polymers on a wide range of rigid and flexible substrates. Integrated optical devices fabricated to date include numerous passive and active elements that achieve a variety of coupling, routing, filtering, and switching functions