Influence of oxygen doping on resistive-switching characteristic of a-Si/c-Si device

The influence of oxygen doping on resistive-switching characteristics of Ag/a-Si/p+-c-Si device was investigated.By oxygen doping in the growth process of amorphous silicon,the device resistive-switching performances,such as the ON/OFF resistance ratios,yield and stability were improved,which may be ascribed to the significant reduction of defect density because of oxygen incorporation.The device I-V characteristics are strongly dependent on the oxygen doping concentration.As the oxygen doping concentration increases,the Si-rich device gradually transforms to an oxygen-rich device,and the device yield,switching characteristics,and stability may be improved for silver/oxygen-doped a-Si/p+-c-Si device.Finally,the device resistive-switching mechanism was analyzed.     

A fractional-N frequency divider for multi-standard wireless transceiver fabricated in 0.18 μm CMOS process

With the rapid evolution of wireless communication technology,integrating various communication modes in a mobile terminal has become the popular trend.Because of this,multi-standard wireless technology is one of the hot spots in current research.This paper presents a wideband fractional-N frequency divider of the multi-standard wireless transceiver for many applications.High-speed divider-by-2 with traditional sourcecoupled-logic is designed for very wide band usage.Phase switching technique and a chain of divider-by-2/3 are applied to the programmable frequency divider with 0.5 step.The phase noise of the whole frequency synthesizer will be decreased by the narrower step of programmable frequency divider.△-Σ modulator is achieved by an improved MASH 1-1-1 structure.This structure has excellent performance in many ways,such as noise,spur and input dynamic range.Fabricated in TSMC 0.18 μm CMOS process,the fractional-N frequency divider occupies a chip area of 1130 × 510μm2 and it can correctly divide within the frequency range of 0.8-9 GHz.With 1.8 V supply voltage,its division ratio ranges from 62.5 to 254 and the total current consumption is 29 mA.     

Coexistence of Grain‐Boundaries‐Assisted Bipolar and Threshold Resistive Switching in Multilayer Hexagonal Boron Nitride

The use of 2D materials to improve the capabilities of electronic devices is a promising strategy that has recently gained much interest in both academia and industry. However, while the research in 2D metallic and semiconducting materials is well established, detailed knowledge and applications of 2D insulators are still scarce. In this paper, the presence of resistive switching (RS) in multilayer hexagonal boron nitride (h‐BN) is studied using different electrode materials, and a family of h‐BN‐based resistive random access memories with tunable capabilities is engineered. The devices show the coexistence of forming free bipolar and threshold‐type RS with low operation voltages down to 0.4 V, high current on/off ratio up to 10⁶, and long retention times above 10 h, as well as low variability. The RS is driven by the grain boundaries (GBs) in the polycrystalline h‐BN stack, which allow the penetration of metallic ions from adjacent electrodes. This reaction can be boosted by the generation of B vacancies, which are more abundant at the GBs. To the best of our knowledge, h‐BN is the first 2D material showing the coexistence of bipolar and threshold RS, which may open the door to additional functionalities and applications.     

Novel Packet Switching for Green IP Networks

A green technology for reducing energy consumption has become a critical factor in ICT industries. However, for the telecommunications sector in particular, most network elements are not usually optimized for power efficiency. Here, we propose a novel energy‐efficient packet switching method for use in an IP network for reducing unnecessary energy consumption. As a green networking approach, we first classify the network nodes into either header or member nodes. The member nodes then put the routing‐related module at layer 3 to sleep under the assumption that the layer in the OSI model can operate independently. The entire set of network nodes is then partitioned into clusters consisting of one header node and multiple member nodes. Then, only the header node in a cluster conducts IP routing and its member nodes conduct packet switching using a specially designed identifier, a tag. To investigate the impact of the proposed scheme, we conducted a number of simulations using well‐known real network topologies and achieved a more energy‐ efficient performance than that achieved in previous studies.     

Fast-switching ferrolectric liquid crystalline polymers containing one or two centres of chirality in the side chain

In a liquid crystalline side chain polyacrylate containing one center of chirality in the terminal alkyl chain of the mesogenic part, switching times of 200–400 μs were measured in the SmC^* phase. Below this phase an unidentified phase exists, which shows electroclinic-like switching. The phase transition between those two phases can be shifted by applying an electric field. At higher molecular weights three subphases emerge in the SmC^* region. Variation of the spacer length revealed, for the first time, ferroelectric switching even at a spacer length of only two CH₂ groups. By shifting the centre of chirality into the spacer of the side group a polymer resulted, which shows electroclinic switching in the SmC^* phase, changing to ferroelectric switching when the voltage is increased. Incorporation of an oxirane ring as chiral building block into the spacer yielded a polymer that shows a sign inversion of the spontaneous polarization in the SmC^* phase. A polymer containing a dioxolane carbonic ester as chiral unit exhibits three switching states, with the third state existing at a low or zero electric field. This phenomenon is known for antiferroelectric liquid crystals. By doping a racemic LC polymer with a chiral monomeric LC we induced a spontaneous polarization. Colored FLC polymers were obtained by two different approaches. In an FLC–dye copolymer, increasing switching speed in three different chiral smectic phases was observed when increasing the dye concentration.     

在线富集-HPLC法测定水溶液中多环芳烃

本文采用在线富集-HPLC 法测定水溶液中多环芳烃。先使样品中的组分浓缩在一支短的富集柱上,然后切换阀门,将富集物洗脱到 RPHPLC 的体系中进行分离,并用紫外和荧光检定器对冼脱物进行检测。为了提高检测灵敏度和选择性,实验中采用了荧光波长程序技术。考察了富集的最佳条件,并比较了在线法与离线法的测定结果。     

Determination of metoprolol in human plasma by column switching high-performance liquid chromatography

Summary Retention characteristics of metoprolol have been studied in reversed phase mode on RP2, RP8 and CN columns. The plots of retention time as a function of the acetonitrile content and of the ionic strength of the mobile phase permitted the choice of the best conditions to separate metoprolol from plasma components by switching of these three types of columns.Human plasma (0.5–1 ml) diluted with water is first injected on a RP2 column (25–40 m particle diameter, prepared by dry packing) and rinsed with water. The sample is then back eluted with acetonitrile-0.022 M acetate buffer (7525, v:v) and switched to a CN column (10 cm long, 5 m particle diameter). The heart cut of the eluate is selected and loaded on a RP8 analytical column (25 cm long, 5 m particle diameter) with acetonitrile-0.088 M acetate buffer (7525, v:v) as mobile phase.Auto-sampler and switching valves are actuated automatically by a computing integrator based on a fixed time schedule. The duration of one cycle is about 30 min, but the last analytical step is about 15 min and represents the time interval between two injections. Metoprolol, its alpha-hydroxy metabolite and the internal standard are detected by fluorescence (_ex= 225 nm; _em > 320 nm).Presented at the 14th International Symposium on Chromatography London, September, 1982     

银莱汤中主要成分的UPLC多波长宽动态测定及质量评价研究

采用超高效液相色谱(UPLC)定量测定银莱汤中10种有效成分的含量并用于其质量评价.采用Wa-ters ACQUITY UPLC HSS T3色谱柱(2.1 mm × 100 mm,1.8 μm),以0.1％甲酸水溶液-0.1％甲酸乙腈为流动相梯度洗脱,3波长切换(0～10 min,320 nm;10～16 min,3...     

开关电源噪声的形成及抑制方法

开关电源产生的噪声比常规线性电源产生的噪声大得多。介绍了开关电源噪声的类型,分析了开关电源噪声的产生原因,讨论了开关电源中噪声的抑制方法,介绍了几种抑制开关电源中噪声的实用电路。     

Energy principle of ferroelectric ceramics and single domain mechanical model

Many physical experiments have shown that the domain switching in a ferroelectric material is a complicated evolution process of the domain wall with the variation of stress and electric field. According to this mechanism, the volume fraction of the domain switching is introduced in the constitutive law of ferroelectric ceramic and used to study the nonlinear constitutive behavior of ferroelectric body in this paper. The principle of stationary total energy is put forward in which the basic unknown quantities are the displacement u _i , electric displacement D _i and volume fraction ρ _I of the domain switching for the variant I. Mechanical field equation and a new domain switching criterion are obtained from the principle of stationary total energy. The domain switching criterion proposed in this paper is an expansion and development of the energy criterion. On the basis of the domain switching criterion, a set of linear algebraic equations for the volume fraction ρ _I of domain switching is obtained, in which the coefficients of the linear algebraic equations only contain the unknown strain and electric fields. Then a single domain mechanical model is proposed in this paper. The poled ferroelectric specimen is considered as a transversely isotropic single domain. By using the partial experimental results, the hardening relation between the driving force of domain switching and the volume fraction of domain switching can be calibrated. Then the electromechanical response can be calculated on the basis of the calibrated hardening relation. The results involve the electric butterfly shaped curves of axial strain versus axial electric field, the hysteresis loops of electric displacement versus electric filed and the evolution process of the domain switching in the ferroelectric specimens under uniaxial coupled stress and electric field loading. The present theoretic prediction agrees reasonably with the experimental results given by Lynch. The project supported by the National Natural Science Foundation of China (10572138).