旋转对称性对红外超材料完美吸收器特性的影响

研究了超材料完美吸收器的旋转对称性对其吸收特性的影响.吸收器由金属颗粒/电介质/金属薄膜三层结构组成.以最上层是方形金属块为例,并通过在其y方向不同边沿处引入空气孔研究了四重、二重和非旋转对称吸收器的吸收特性.理论结果表明,当入射光偏振平行于x轴或y轴时,四重旋转对称结构有一个完全相同的吸收峰;二重旋转对称结构吸收峰会在入射光偏振平行于x轴时劈裂成两个峰;而无论入射光偏振平行于x轴或y轴,非旋转对称结构的吸收峰都会劈裂成两个峰.不同重数旋转对称性对吸收峰特性影响的结果将有助于设计新型的偏振无关的吸收器.     

低功耗、高线性度的电流模可编程增益放大器

本文设计了一种电流模式下,带电流模直流失调消除（DCOC）电路的class-AB的可编程增益放大器。电路基于电流放大器,可以实现40dB的增益动态范围,增益步长为1dB。电流模可编程增益放大器由0.18-μm CMOS工艺实现,电路具有较宽的电流增益范围、较低的直流功耗和较小的芯片面积。放大器电路芯片面积为0.099μm2,在1.8V电压下静态电流为2.52mA。测试结果表明电路增益范围为10dB到50dB,增益误差为±0.40dB,OP1dB为11.80dBm到13.71dBm,3dB带宽为22.2MHz到34.7MHz。     

基于5G通信技术的无线网络节能降耗技术研究

近年来,可持续发展和绿色发展越来越受到能源消耗型企业的重视。通信产业作为关乎民生的重要产业,各大运营商的经营规模和利润产出极为可观,但其作为资源消耗性企业,在能耗和碳排放方面的规模也无法忽视。通信产业现有的节能减排策略以减少基站环境控制设备的功耗为主,缺少完善的基于基站设备的能耗控制技术。文中结合实际情况,简要叙述了各种技术在无线网络的节能降耗方面的作用。     

An integrated 0.38–6 GHz, 9–12 GHz fully differential fractional-N frequency synthesizer for multi-standard reconfigurable MIMO communication application

A wide-band fully differential fractional-N frequency synthesizer for multi-standard application is presented. The single fully differential LC–VCO with 28.5 % tuning rang and a set of dividers, quadrature self-mixer are designed to accomplish the multi-frequency bands with the frequency band from 0.38 to 6 GHz and from 9.0 to 12 GHz. It covers several wireless standards. A novel high isolation multiplexer is presented to achieve the frequency band selection. This chip was implemented with 65 nm CMOS technology and the maximum consumption is 20.05 mA from 1.2 V power supply. It occupies an active area of 1.5 mm². The measured typical phase noise of the frequency synthesizer is ?114.6 dBc/Hz from 1 MHz offset for 4.85 GHz output.     

一种利用激光跟踪仪标定线阵相机的方法

为提高线阵相机的标定的灵活性和准确度,研究了一种利用激光跟踪仪辅助标定线阵相机的内参数和外方位参数的方法。借助激光跟踪仪测量靶标上的标记点获得靶标的位置和姿态,根据交比不变性质和空间坐标变换计算成像特征点的三维坐标。引入成像畸变模型补偿成像过程中产生的畸变,提高像点位置精度。应用优化算法估计待标定参数的精确解。本文方法解除了对靶标移动方向和距离的严格限制,允许靶标自由移动,既提高了标定工作的便利性又保证了成像特征点三维坐标的精度。标定过程中,使靶标均匀覆盖整个视场空间,能够更准确地反映相机参数。通过计算机仿真和实验验证了标定方法的可行性和稳定性,实验得到成像特征点重投影像点位置偏差均方根为0.21pixel。     

High-Performance Green Thick-Film Ternary Organic Solar Cells Enabled by Crystallinity Regulation

The power conversion efficiency (PCE) of organic solar cells (OSCs) has reached high values of over 19%. However, most of the high-efficiency OSCs are fabricated by spin-coating with toxic solvents and the optimal photoactive layer thickness is limited to 100 nm, limiting practical development of OSCs. It is a great challenge to obtain ideal morphology for high-efficiency thick-film OSCs when using non-halogenated solvents due to the unfavorable film formation kinetics. Herein, high-efficiency ternary thick-film (300 nm) OSCs with PCE of 15.4% based on PM6:BTR-Cl:CH1007 are fabricated by hot slot-die coating using non-halogenated solvent (o-xylene) in the air. Compared to PM6:BTR-Cl:Y6 blends, the stronger pre-aggregation of CH1007 in solution induces the earlier aggregation of CH1007 molecules and longer aggregation time, and thus results in high and balanced crystallinity of donors and acceptor in CH1007-based ternary film, which led to high-carrier mobility and suppressed charge recombination. The ternary strategy is further used to fabricate high-efficiency, thick-film, large-area, and flexible devices processed from non-halogenated solvents, paving the way for industrial development of OSCs.     

Gelable and Adhesive Powder for Lethal Non-Compressible Hemorrhage Control

Hemostatic powders are widely used in clinical and emergency situations but often exhibit low wet adhesion, cytotoxicity concerns, and do not work well for lethal non-compressible hemorrhage. Here a new kind of gelable and adhesive powder (GAP) is developed, which integrates chitosan microspheres (CM), tetra-armed poly(ethylene glycol) amine (Tetra-PEG-NH₂), and tetra-armed poly(ethylene glycol) succinimidyl succinate (Tetra-PEG-SS). Upon application to the wound site, the macroporous CM can rapidly absorb the interfacial liquids, and meanwhile, the hydrated GAP turns into hydrogel (crosslinking between Tetra-PEG-SS and CM/Tetra-PEG-NH₂) with stable and robust adhesion to the wet tissue though covalent bonding. The in vitro and in vivo results suggest that the GAP with optimized formulation exhibits strong tissue adhesive, high burst pressure, and enhanced blood clotting ability, as well as excellent biocompatibility and on-demand removal properties. A significantly improved hemostatic efficacy is demonstrated in the rat liver, spleen, and femoral artery injury models compared to that of the CM, commercial fibrin glue, and Yunnan Baiyao (YB). The GAP can also halt the severe bleeding from pig visceral organs. Overall, the proposed GAP has many advantages including good biocompatibility, rapid and effective hemostasis, low cost, and ease of use, making it as a promising hemostat for lethal non-compressible hemorrhage control.     

Ni3N–CeO2 Heterostructure Bifunctional Catalysts for Electrochemical Water Splitting

Developing low-cost and high-efficient bifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is greatly significant for water electrolysis. Here, Ni₃N-CeO₂/NF heterostructure is synthesized on the nickel foam, and it exhibits excellent HER and OER performance. As a result, the water electrolyzer based on Ni₃N-CeO₂/NF bifunctional catalyst only needs 1.515 V@10 mA cm⁻², significantly better than that of Pt/C||IrO₂ catalysts. In situ characterizations unveil that CeO₂ plays completely different roles in HER and OER processes. In situ infrared spectroscopy and density functional theory calculations indicate that the introduction of CeO₂ can optimizes the structure of interface water, and the synergistic effect of Ni₃N and CeO₂ improve the HER activity significantly, while the in situ Raman spectra reveal that CeO₂ accelerates the reconstruction of O_V (oxygen vacancy)-rich NiOOH for boosting OER. This study clearly unlocks the different catalytic mechanisms of CeO₂ for boosting the HER and OER activity of Ni₃N for water splitting, which provides the useful guidance for designing the high-performance bifunctional catalysts for water splitting.     

2D MoN1.2-rGO Stacked Heterostructures Enabled Water State Modification for Highly Efficient Interfacial Solar Evaporation

Improving interfacial solar evaporation performance is crucial for the practical application of this technology in solar-driven seawater desalination. Lowering evaporation enthalpy is one of the most promising and effective strategies to significantly improve solar evaporation rate. In this study, a new pathway to lower vaporization enthalpy by introducing heterogeneous interactions between hydrophilic hybrid materials and water molecules is developed. 2D MoN_1.2 nanosheets are synthesized and integrated with rGO nanosheets to form stacked MoN_1.2-rGO heterostructures with massive junction interfaces for interfacial solar evaporation. Molecular dynamics simulation confirms that atomic thick 2D MoN_1.2 and rGO in the MoN_1.2-rGO heterostructures simultaneously interact with water molecules, while the interactions are remarkably different. These heterogeneous interactions cause an imbalanced water state, which easily breaks the hydrogen bonds between water molecules, leading to dramatically lowered vaporization enthalpy and improved solar evaporation rate (2.6 kg m⁻² h⁻¹). This study provides a promising strategy for designing 2D-2D heterostructures to regulate evaporation enthalpy to improve solar evaporate rate for clean water production.     

The Heterointerface between Fe1/NC and Selenides Boosts Reversible Oxygen Electrocatalysis

The rational design and construction of efficient and inexpensive bifunctional oxygen electrocatalysts are highly desirable for the development of rechargeable Zn–air batteries (ZABs). Although single-atom Fe sites anchored on N-doped carbon catalysts (Fe₁/NC) ensure high oxygen reduction reaction activity, their unitary atomically dispersed active center faces difficult condition in catalyzing oxygen evolution reaction simultaneously. Herein, a composite catalyst containing heterointerface between Fe₁/NC and selenides ((Fe,Co)Se₂) is constructed. The obtained (Fe,Co)Se₂@Fe₁/NC exhibits extremely narrow potential gap of 0.616 V and remarkable stability in alkaline media, outperforming the benchmark catalysts (Pt/C+RuO₂: 0.720 V). Experimental results and density functional theory calculations reveal that heterointerface between Fe₁/NC and (Fe,Co)Se₂ accelerates the electron transfer and provides more moderate adsorption sites, which endow (Fe,Co)Se₂@Fe₁/NC with extremely high bifunctional oxygen catalytic activity. This study not only provides a superior bifunctional catalyst for ZABs, but also enriches the application of single-atom catalysts in multifunctional energy storage and conversion devices.