Ternary Conductance Switching Realized by a Pillar[5]arene-Functionalized Two-Dimensional Imine Polymer Film

Nowadays, most manufacturing memory devices are based on materials with electrical bistability (i. e., “0” and “1”) in response to an applied electric field. Memory devices with multilevel states are highly desired so as to produce high-density and efficient memory devices. Herein, we report the first multichannel strategy to realize a ternary-state memristor. We make use of the intrinsic sub-nanometer channel of pillar[5]arene and nanometer channel of a two-dimensional imine polymer to construct an active layer with multilevel channels for ternary memory devices. Low threshold voltage, long retention time, clearly distinguishable resistance states, high ON/OFF ratio (OFF/ON1/ON2=1 : 10 : 10³), and high ternary yield (75 %) were obtained. In addition, the flexible memory device based on 2DP_TPAZ+TAPB can maintain its stable ternary memory performance after being bent 500 times. The device also exhibits excellent thermal stability and can tolerate a temperature as high as 300 °C. It is envisioned that the results of this work will open up possibilities for multistate, flexible resistive memories with good thermal stability and low energy consumption, and broaden the application of pillar[n]arene.     

Development of the diffusive gradient in thin films technique for the measurement of labile mercury species in waters

The diffusive gradients in thin films (DGT) technique, utilizing resin gel with ion-exchange resin Duolite GT73 and new ion-exchange resin Ambersep GT74, was investigated for the accumulation of four mercury species (Hg²⁺, CH₃Hg⁺, C₂H₅Hg⁺, C₆H₅Hg⁺). The diffusion coefficients of mercury species in agarose gel calculated on the basis of Fick’s Law were mercury species-specific. The diffusion coefficients of Hg²⁺ and CH₃Hg⁺ at 25 °C (9.07 ± 0.23 × 10⁻⁶ cm² s⁻¹ and 9.06 ± 0.30 × 10⁻⁶ cm² s⁻¹, respectively) were very similar, but the diffusion coefficients of C₂H₅Hg⁺ (6.87 ± 0.23 × 10⁻⁶ cm² s⁻¹) and C₆H₅Hg⁺ (3.86 ± 0.19 × 10⁻⁶ cm² s⁻¹) were significantly lower. Influence of experimental conditions (pH, selected cations, chlorides and humic substance) on mercury species accumulation by DGT was studied. The DGT technique was applied to river water spiked with mercury species.     

多孔介质传热传质中耦合扩散效应的研究

本文采用加罚函数有限元方法数值模拟在温度梯度和浓度梯度同时存在时双浮升力自然对流及其伴随的传热传质,着重探讨了多孔介质中传热传质的交叉耦合扩散Soret效应和Dufour效应的基本影响规律,展示了流场、温度场和浓度场随热附加扩散准则数和扩散附加热准则数的变化状况。     

Storage of Electrical Information in Metal–Organic‐Framework Memristors

Single crystals of a cyclodextrin‐based metal–organic framework (MOF) infused with an ionic electrolyte and flanked by silver electrodes act as memristors. They can be electrically switched between low and high conductivity states that persist even in the absence of an applied voltage. In this way, these small blocks of nanoporous sugar function as a non‐volatile RRAM memory elements that can be repeatedly read, erased, and re‐written. These properties derive from ionic current within the MOF and the deposition of nanometer‐thin passivating layers at the anode flanking the MOF crystal. The observed phenomena are crucially dependent on the sub‐nanometer widths of the channels in the MOF, allowing the passage of only smaller ions. Conversely, with the electrolyte present but no MOF, there are no memristance or memory effects.     

巯基改性聚乙烯醇为结合相的薄膜扩散梯度技术

利用巯基乙酸改性了聚乙烯醇,制得了巯基聚乙烯醇(PVA-SH).研究了以1.0 mmol/L PVA-SH溶液为结合相的薄膜扩散梯度(DGT)装置(PVA-SH DGT)对Cd2+测量的有效性; 考察了pH值、离子强度对PVA-SH DGT累积Cd2+的影响; 测量了PVA-SH DGT对Cd2+的饱和累积容量.实验表明: 巯基乙酸成功地接枝到PVA上,巯基含量为1.65%(wt%); PVA-SH DGT对Cd2+的饱和累积容量为0.234 mol/L;当pH值在5.5～9.9范围内、离子强度在0.0001～0.7 mol/L内基本不影响PVA-SH DGT对Cd2+的累积; PVA-SH DGT能够定量测定水中的Cd2+,回收率为100.7%,线性相关系数r=0.9812.结果表明: PVA-SH可以作为DGT技术新的液态结合相.     

Continuous dependence on the Soret coefficient for double diffusive convection in Darcy flow

In this paper, the Darcy model is used to describe the double diffusive flow of a fluid containing a solute. Continuous dependence of the solution on the Soret coefficient is established.     

A note on blow‐up for fast diffusive p‐Laplacian with sources

In this note we improve the result of Theorem 3.1 in Yin and Jin (Math. Meth. Appl. Sci. 2007; 30 (10):1147–1167) and establish a blow‐up result for certain solution with positive initial energy. Copyright © 2008 John Wiley & Sons, Ltd.     

Kinetic Relaxation Models for Energy Transport

Kinetic equations with relaxation collision kernels are considered under the basic assumption of two collision invariants, namely mass and energy. The collision kernels are of BGK-type with a general local Gibbs state, which may be quite different from the Gaussian. By the use of the diffusive length/time scales, energy transport systems consisting of two parabolic equations with the position density and the energy density as unknowns are derived on a formal level. The H theorem for the kinetic model is presented, and the entropy for the energy transport systems, which is inherited from the kinetic model, is derived. The energy transport systems for specific examples of the global Gibbs state, such as a power law with negative exponent, a cut-off power law with positive exponent, the Maxwellian, Bose–Einstein, and Fermi–Dirac distributions, arepresented. MSC classification (2000): Primary: 82C40, 35B40; Secondary: 35K55, 45K05, 82D05, 85A05x     

Patterns in the Kardar-Parisi-Zhang equation

We review a recent asymptotic weak noise approach to the Kardar-Parisi-Zhang equation for the kinetic growth of an interface in higher dimensions. The weak noise approach provides a many-body picture of a growing interface in terms of a network of localized growth modes. Scaling in 1d is associated with a gapless domain wall mode. The method also provides an independent argument for the existence of an upper critical dimension.