新型槽栅MOSFETs的特性

采用SIVALCO软件对槽栅与平面器件进行了仿真对比分析,结果表明槽栅器件能够有效地抑制短沟道及热载流子效应,而拐角效应是槽栅器件优于平面器件特性更加稳定的原因.对自对准工艺下成功投片所得沟道长度为140nm的槽栅器件进行测量,结果有力地证明了槽栅器件较平面器件的优越性.     

MOS AlGaN/GaN HEMT研制与特性分析

研制出在蓝宅石衬底上制作的MOS AIGaN/GaN HEMT.器件栅长1um,源漏间距4um,采用电子束蒸发4nm的Si02做栅介质.在4V栅压下器件饱和电流达到718mA/mm,最大跨导为172mS/mm,ft和fmax分别为8.1和15.3GHz.MOS HEMT栅反向泄漏电流与未做介质层的肖特基栅相比,在反偏10V时由2.1×10-8mA/mm减小到8.3×10-9mA/mm,栅漏电流减小2个数量级.MOS AIGaN/GaN HEMT采用薄的栅介质层,在保证减小栅泄漏电流的同时未引起器件跨导明显下降.     

定位技术在奥运“城市通”系统中的应用

作为2008年奥运会的举办城市,北京将会成为国内外游客主要聚集的地区,为了向用户提供"随时随地、方便快捷"的信息查询和位置查询服务,中国网通集团研究院开发了奥运"城市通"系统,通过该系统,用户可以使用一个具有定位功能的小灵通终端进行餐饮、娱乐、观光的出行导航和综合城市信息、企业信息的查询,因此,定位技术是实现"城市通"业务的核心,为开发其他增值业务提供了基础,本文将详细介绍定位技术在"城市通"业务中的应用。     

Nanostructured Metal Sulfides: Classification,Modification Strategy,and Solar-Driven CO2 Reduction Application

Solar-driven conversion of CO₂ into high value-added fuels is expected to be an environmental-friendly and sustainable approach for relieving the greenhouse gas effect and countering energy crisis. Metal sulfide semiconductors with wide photoresponsive range and favorable band structures are suitable photocatalysts for CO₂ photoreduction. This review summarizes the recent progress on metal sulfide semiconductors for photocatalytic CO₂ reduction. First, the fundamentals, mechanisms and some principles, like product selectivity, of photocatalytic CO₂ reduction are introduced. Then, according to the elemental composition, the metal sulfide photocatalysts applied for CO₂ reduction are classified into binary (CdS, ZnS, MoS₂, SnS₂, Bi₂S₃, In₂S₃,Cu₂S, NiS/NiS₂, and CoS₂), ternary (ZnIn₂S₄, CdIn₂S₄, CuInS₂, Cu₃SnS₄, and CuGaS₂), and quaternary (Cu₂ZnSnS₄) systems, in which their crystal structures, photochemical characteristics, and photocatalytic CO₂ reduction applications are systematically demonstrated. Especially, the diverse modification strategies for improving the activity and product selectivity of photocatalytic CO₂ reduction on these metal sulfides are summarized. Finally, the current challenges and future directions for the development of metal sulfide photocatalysts for CO₂ reduction are proposed. This review is expected to serve as a powerful reference for exploiting high-efficiency metal sulfide photocatalysts for CO₂ conversion and furthering related mechanism understanding.     

Single Small Molecule-Assembled Mitochondria Targeting Nanofibers for Enhanced Photodynamic Cancer Therapy In Vivo

Photodynamic therapy (PDT) has emerged as an attractive alternative in cancer therapy, but its therapeutic effects are limited by the nonselective subcellular localization and poor intratumoral retention of small-molecule photosensitizes. Here a fiber-forming nanophotosensitizer (PQC NF) that is composed of mitochondria targeting small molecules of amphiphilicity is reported. Harnessing the specific mitochondria targeting, the light-activated PQC NFs produce approximately 110-fold higher amount of reactive oxygen species in cells than free photosensitizers and can dramatically induce mitochondrial disruption to trigger intense apoptosis, showing 20–50 times better in vitro anticancer potency than traditional photosensitizers. As fiber-shaped nanomaterials, PQC NFs also demonstrated a long-term retention in tumor sites, solving the challenge of rapid clearance of small-molecule photosensitizers from tumors. With these advantages, PQC NFs achieve a 100% complete cure rate in both subcutaneous and orthotopic oral cancer models with the administration of only a single dose. This type of single small molecule-assembled mitochondria targeting nanofibers offers an advantageous strategy to improve the in vivo therapeutic effects of conventional PDT.     

Interlamellar Lithium-Ion Conductor Reformed Interface for High Performance Lithium Metal Anode

Lithium metal anodes are promising for application in new-type secondary batteries. Unfortunately, low cycle life and safety peril induced by uncontrollable dendrites growth and weak solid electrolyte interface (SEI) have blocked their utilization. In this work, an interlamellar lithium-ion conductor of lithium-montmorillonite (Li-MMT) is applied to enhance the SEI properties, inhibit dendrites-germination, and thus significantly enhance electrochemical performance. Such a well-designed Li-MMT SEI not only possesses inherent fast lithium-ion channels, but also works as a reservoir to supply adequate lithium-ions in the interlaminations and periphery of Li-MMT nanosheets, offering fast lithium-ion transfer in interlaminations and sheet-to-sheet. Furthermore, the strong trend of lithium-ion absorption of Li-MMT is confirmed by density functional theory calculations and stable lithium deposition under Li-MMT SEI layer at 10 mA cm⁻² is verified via finite element modeling. As a result, a steady lithium deposition process without dendrites is achieved. Coulombic efficiency of the half-cell accomplishes a mean value of 99.1% over 400 cycles at 1 mA cm⁻², while Li-LiFePO₄ full cells show a stable capacity up to 120 mAh g⁻¹ and steady circulation over 400 loops at 1C. This work offers a novel strategy to design a high-performance SEI layer and suppress dendrite growth.     

Moisture-Induced Reversible Phase Conversion of Cesium Copper Iodine Nanocrystals Enables Advanced Anti-Counterfeiting

Hydrochromic materials have attracted widespread attention in the fields of anti-counterfeiting because of their ability of the reversible light absorption and/or emission properties in response to water. Here, for the first it is demonstrated that the ternary copper halides Cs₃Cu₂I₅ nanocrystals (NCs) possess excellent hydrochromic properties. The prepared Cs₃Cu₂I₅ NCs films can dynamically extract and insert CsI by exposing/removing water to realize the reversible conversion between blue-emissive Cs₃Cu₂I₅ and yellow-emissive CsCu₂I₃. Interestingly, polymethyl methacrylate (PMMA) coated Cs₃Cu₂I₅ can effectively avoid the extraction of CsI and maintain long-term stability in the water. Further, the hydrochromic Cs₃Cu₂I₅ and water-resistant Cs₃Cu₂I₅@PMMA are used as the inks to synergistically act on anti-counterfeiting information to achieve multiple encryption effects, which can clearly identify and authenticate the effective information after moisture decryption. Importantly, the pattern can be re-encrypted to the invalid pattern after water evaporation. In addition, the anti-counterfeiting pattern has excellent stability during repeated encryption/decryption conversion cycles, which can not only balance the accessibility of anti-counterfeiting information but also effectively improve the security of information. This new discovery may not only deepen the understanding of Cs₃Cu₂I₅ but also provide new options for the design of hydrochromic materials for anti-counterfeiting information.     

High‐Efficient Clearable Nanoparticles for Multi‐Modal Imaging and Image‐Guided Cancer Therapy

Renal‐clearable nanoparticles have made it possible to overcome the toxicity by nonspecific accumulation in healthy tissues/organs due to their highly efficient clearance characteristics. However, their tumor uptake is relatively low due to the short blood circulation time and rapid body elimination. Here, this problem is addressed by developing renal‐clearable nanoparticles by controlled coating of sub‐6 nm CuS nanodots (CuSNDs) on doxorubicin ladened mesoporous silica nanoparticles (pore size ≈6 nm) for multimodal application. High tumor uptake of the as‐synthesized nanoparticles (abbreviated as MDNs) is achieved due to the longer blood circulation time. The MDNs also show excellent performance in bimodal imaging. Moreover, the MDNs demonstrated a photothermally sensitive drug release and pronounced synergetic effects of chemo‐photothermal therapy, which were confirmed by two different tumor models in vivo. A novel key feature of the proposed synthesis is the use of renal‐clearable CuSNDs and biodegradable mesoporous silica nanoparticles which also are renal‐clearable after degradation. Therefore, the MDNs would be rapidly degraded and excreted in a reasonable period in living body and avoid long‐term toxicity. Such biodegradable and clearable single‐compartment theranostic agents applicable in highly integrated multimodal imaging and multiple therapeutic functions may have substantial potentials in clinical practice.     

New Strategy for Polysulfide Protection Based on Atomic Layer Deposition of TiO2 onto Ferroelectric‐Encapsulated Cathode: Toward Ultrastable Free‐Standing Room Temperature Sodium–Sulfur Batteries

The room temperature (RT) sodium–sulfur batteries (Na–S) hold great promise for practical applications including energy storage and conversion due to high energy density, long lifespan, and low cost, as well based on the abundant reserves of both sodium metal and sulfur. Herein, freestanding (C/S/BaTiO₃)@TiO₂ (CSB@TiO₂) electrode with only ≈3 wt% of BaTiO₃ additive and ≈4 nm thickness of amorphous TiO₂ atomic layer deposition protective layer is rational designed, and first used for RT Na–S batteries. Results show that such cathode material exhibits high rate capability and excellent durability compared with pure C/S and C/S/BaTiO₃ electrodes. Notably, this CSB@TiO₂ electrode performs a discharge capacity of 524.8 and 382 mA h g^?1 after 1400 cycles at 1 A g^?1 and 3000 cycles at 2 A g^?1, respectively. Such superior electrochemical performance is mainly attributed from the “BaTiO₃‐C‐TiO₂” synergetic structure within the matrix, which enables effectively inhibiting the shuttle effect, restraining the volumetric variation and stabilizing the ionic transport interface.     

DNA‐Templated Magnetic Nanoparticle‐Quantum Dot Polymers for Ultrasensitive Capture and Detection of Circulating Tumor Cells

Circulating tumor cell (CTC) enumeration and analysis has emerged as an important platform for cancer diagnosis and prognosis. A great challenge, however, is to efficiently capture low abundant CTCs with high purity from blood samples in a rapid and high‐throughput manner for accurate and sensitive CTC detection. Herein, a new class of DNA‐templated magnetic nanoparticle‐quantum dot (QD)‐aptamer copolymers (MQAPs) is developed for rapid magnetic isolation of CTCs from human blood with high capture efficiency and purity approaching 80%. The phenotype of CTCs is simultaneously profiled with QD photoluminescence (PL) at single cell level. These MQAPs are constructed through hybridization chain reaction to achieve amplified magnetic response, extraordinary binding selectivity for target cells over background cells, and ultra bright ensemble QD PL for single cell detection. MQAPs are free from nonspecific binding that would otherwise compromise the capture purity of target cells. As a result, facile isolation and enumeration of rare CTCs in blood samples could be achieved in 20 min with high sensitivity and accuracy.