Improved voltage clamping scheme for ZVS PWM three-level converter

This paper proposes an improved zero-voltage-switching pulsewidth-modulation (ZVS PWM) three-level converter, which is improved from the original ZVS PWM three-level converter by merely exchanging the position of the resonant inductance and the transformer, such that the transformer is connected with the lagging switches. The improved converter has several advantages over the original, e.g., the clamping diodes conduct only once in a switching period, and the resonant inductance current is smaller in zero state, leading to a higher efficiency and reduced duty-cycle loss. A blocking capacitor is usually introduced to the primary side to prevent the transformer from saturating. This paper analyzes the effects of the blocking capacitor in different positions, and a best scheme is determined. A 2.5-kW prototype converter verifies the effectiveness of the improved converter and the best scheme for the blocking capacitor.     

HomePNA通信中的技术与应用

正如局域网 (LAN)是为了满足企业内多用户互连和资源共享 ,为满足家庭中多种数字设备互连和资源共享 ,家庭电话线网设备 (HomePNA)应运而生。文章叙述了HomePNA通信中所需的技术与应用。     

A Hollow‐Core,Magnetic, and Mesoporous Double‐Shell Nanostructure: In Situ Decomposition/Reduction Synthesis,Bioimaging, and Drug‐Delivery Properties

A novel in situ decomposition/reduction approach is developed to manu­facture hollow core, magnetic, and mesoporous double‐shell nanostructures (HMMNSs) via in situ decomposition and reduction of a β‐FeOOH nanorod core and organosilicate‐incorporated silica‐shell precursor. The formed HMMNSs are then aminated by silanization for further covalent conjugation to rhodamine B isothiocyanate (RBITC) and poly(ethylene glycol) (PEG) chains. The resultant RBITC‐grafted and PEGylated nanocomposites (HMMNS–R/Ps) have excellent blood compatibility and very low cytotoxicity towards HeLa and MCF‐7 cells, and can be taken up by cancer cells effectively in a dose‐dependent manner, as confirmed by in vitro flow cytometry, confocal luminescence imaging, and magnetic resonance imaging (MRI) studies. In vivo MRI studies coupled with Prussian blue staining of slides from different organs show that the nanocomposites preferentially accumulate in liver and spleen after intravenous injection, which suggests a potential application of the nanocomposites as MRI contrast agents. Importantly, the HMMNS–R/P nanocomposites show high loading capacity for water‐insoluble anticancer drugs (docetaxel or camptothecin) owing to the presence of a large inner cavity and enhanced surface area and pore volume. Furthermore, the drug‐loaded nanocomposites exhibit greater cytotoxicity than the corresponding free drugs. These results confirm that the HMMNS–R/P nanocomposites are promising candidates for simultaneous bioimaging and drug delivery.     

掺稀土元素Tm3+石英光纤的研制

描述用液相掺杂技术研制掺Ｔｍ ３＋ 石英光纤并实现其相关参数的控制,并对掺Ｔｍ ３＋ 浓度及其测量方法进行了讨论。     

Investigation on the critical velocity for liquid loss in immersion lithography

Immersion lithography seeks to extend the resolution of optical lithography by filling the gap between the final optical element and the wafer with a liquid characterized by a high index of refraction. The semiconductor industry demands high throughput, leading to relatively large wafer scanning velocities and accelerations. For higher scanning velocities, an issue that has been identified is the deposition of the immersion liquid while confining a relatively small amount of liquid to the under-lens region. Liquid loss occurs at the receding contact line that forms when a substrate is withdrawn from a liquid, which potentially leads to defects on printed patterns. There has been substantial prior work relative to understanding and building semi-empirical correlations and numerical models to investigate this behavior of the receding three-phase contact line. In the current work, a new liquid injection and collection model with analytic solutions is presented and compared with experimental results, in which the critical velocity for liquid loss is mainly a function of the vacuum degree, the injection flow rate, the properties of the immersion liquid. This correlation allows the critical velocity to be predicted with a given gap height between wafer and lens using only a measurement of the injection speed and knowledge of the fluid properties. Experimentally, glycerin–water mixtures of varying viscosities and different injection flow rates were tested, with variable outlet vacuum degree and inlet speed, showing a mean average error within 12%. This correlation represents a useful tool that can serve to approximately guide the development of fluid control for immersion systems as well as to evaluate alternative immersion fluid candidates to minimize liquid deposition while maximizing throughput.     

The application of single-layer graphene modified with solution-processed TiOx and PEDOT:PSS as a transparent conductive anode in organic light-emitting diodes

There are many challenges for a direct application of graphene as the electrodes in organic electronics due to its hydrophobic surfaces, low work function (WF) and poor conductance. The authors demonstrate a modified single-layer graphene (SLG) as the anode in organic light-emitting diodes (OLEDs). The SLG, doped with the solution-processed titanium suboxide (TiO_x) and poly(3,4-ethylenedio-xythiophene)/poly(styrene sulfonic acid) (PEDOT:PSS), exhibits excellent optoelectronic characteristics with reduced sheet resistance (R_sq), increased work function, as well as over 92% transmittance in the visible region. It is notable that the R_sq of graphene decreased by ∼86% from 628 Ω/sq to 86 Ω/sq and the WF of graphene increased about 0.82 eV from 4.30 eV to 5.12 eV after a modification by using the TiO_x–PEDOT:PSS double interlayers. In addition, the existence of additional TiO_x and PEDOT:PSS layers offers a good coverage to the PMMA residuals on SLG, which are often introduced during graphene transfer processes. As a result, the electrical shorting due to the PMMA residues in the device can be effectively suppressed. By using the modified SLG as a bottom anode in OLEDs, the device exhibited comparable current efficiency and power efficiency to those of the ITO based reference OLEDs. The approach demonstrated in this work could potentially provide a viable way to fabricate highly efficient and flexible OLEDs based on graphene anode.     

Enhanced Ionic/Electronic Transport in Nano‐TiO2/Sheared CNT Composite Electrode for Na+ Insertion‐based Hybrid Ion‐Capacitors

Ion‐insertion capacitors show promise to bridge the gap between supercapacitors of high power densities and batteries of high energy densities. While research efforts have primarily focused on Li⁺‐based capacitors (LICs), Na⁺‐based capacitors (SICs) are theoretically cheaper and more sustainable. Owing to the larger size of Na⁺ compared to Li⁺, finding high‐rate anode materials for SICs has been challenging. Herein, an SIC anode architecture is reported consisting of TiO₂ nanoparticles anchored on a sheared‐carbon nanotubes backbone (TiO₂/SCNT). The SCNT architecture provides advantages over other carbon architectures commonly used, such as reduced graphene oxide and CNT. In a half‐cell, the TiO₂/SCNT electrode shows a capacity of 267 mAh g^?1 at a 1 C charge/discharge rate and a capacity of 136 mAh g^?1 at 10 C while maintaining 87% of initial capacity over 1000 cycles. When combined with activated carbon (AC) in a full cell, an energy density and power density of 54.9 Wh kg^?1 and 1410 W kg^?1, respectively, are achieved while retaining a 90% capacity retention over 5000 cycles. The favorable rate capability, energy and power density, and durability of the electrode is attributed to the enhanced electronic and Na⁺ conductivity of the TiO₂/SCNT architecture.     

Analytical analysis of circular-shaped microshield and conductor-backed coplanar waveguide

In this paper, a new type of circular-shaped microshield and conductor-backed coplanar waveguide is proposed. Analytic closed-form expressions for characteristic impedance and effective dielectric constant for the new line are obtained using conformal mapping method under the assumption of pure-TEM propagation and zero dispersion. The new waveguide proposed by this paper can reduce radiation to much less than the conventional coplanar waveguide and microstrip, and can reduce the current concentration at both the edges of the strip conductor.     

深亚微米VLSI电路中互连线的几何优化设计

基于三维 L aplace方程的 Silvaco Interconnect3D模拟程序数值解 ,对互连寄生电容进行了计算 ,其结果用于 0 .2 5μm CMOS技术互连延迟及串扰的 SPICE模拟中。模拟结果表明 ,基于W/ P=0 .3～ 0 .4的布线准则可以获得最优的互连延迟与串扰 (Crosstalk)特性 ,通过优化互连线及驱动管的几何尺寸可以显著地减小互连线的延迟及串扰噪声。