Low threshold voltage,highly stable electroforming-free threshold switching characteristics in VOx films-based device

Threshold switching (TS) devices have evolved as one of the most promising elements in memory circuit due to their important significance in suppressing crosstalk current in the crisscross array structure. However, the issue of high threshold voltage (V_th) and low stability still restricts their potential applications. Herein, the vanadium oxide (VO_x) films deposited by the pulsed laser deposition (PLD) method are adopted as the switching layer to construct the TS devices. The TS devices with Pt/VO_x/Pt/PI structure exhibit non-polar, electroforming-free, and volatile TS characteristics with an ultralow V_th (+0.48 V/−0.48 V). Besides that, the TS devices also demonstrates high stability, without obviously performance degradations after 350 cycles of endurance measurements. Additionally, the transition mechanism is mainly attributed to the synergistic effect of metal-insulator transition of VO₂ and oxygen vacancies. Furthermore, the nonvolatile bipolar resistance switching behaviors can be obtained by changing oxygen pressure during the deposition process for switching films. This work demonstrates that vanadium oxide film is a good candidate as switching layer for applications in the TS devices and opens an avenue for future electronics.     

Piezoelectric properties and microstructure of ceramicrete-based piezoelectric composites

Inorganic piezoelectric ceramic composite is the potential sensing element for long-term structural health monitoring due to its excellent durability and compatibility. In this study, a Ceramicrete-based piezoelectric composite is proposed preliminarily, in which the magnesium potassium phosphate cement is used as the matrix and the lead zirconate titanate particle is utilized as the functional phase. Piezoelectric properties test and microstructure analysis are performed to evaluate the testing samples. Results show that the piezoelectric performance of the composite increase with the increase of piezoelectric ceramic particle size. The value of the piezoelectric strain factor (d₃₃) can reach 83.8 pC/N, while the corresponding piezoelectric voltage factor (g₃₃) is 50.1 × 10^-3 V•m/N at the 50th day after polarization. Microstructure analysis illustrates that the interfacial transition zone (ITZ) between the matrix and the particles is dense. Moreover, the influence of aging on the composite is attributed to the continuous hydration after polarization. It indicates that the composites have a higher piezoelectric performance, which can be regarded as a promising sensing element material.     

对“垃圾衍生燃料”RDF之探析

当前,我国水泥工业在可燃废弃物应用技术方面都还处于一家一户、自制自用、效率极低的初级阶段。发达国家的替代燃料:“垃圾衍生燃料”RDF、“固体回收燃料”SRF、“次煤”Subcoal和“纸塑垃圾衍生燃料”RPF制成的原材料都是可燃废弃物,只是处理工艺技术不同或者由垃圾中分拣出的可燃废弃物不同,制成颗粒状衍生燃料的品质不同,这些都可以替代部分甚或替代全部化石燃料在水泥窑炉中应用。我国大力发展“替代燃料”产业,有助于水泥工业消纳更多的“可燃废弃物”,为改善环境尤其是城镇环境和面貌,为我国的节能减排和绿色高质量发展发挥更大的作用。     

The influence of iodide on glass transition temperature of high-pressure nuclear waste glasses

The glass transition temperature (T_g) is a key parameter to investigate for application in nuclear waste immobilization in borosilicate glasses. T_g for several glasses containing iodine (I) has been measured in order to determine the I effect on T_g. Two series of glass composition (ISG and NH) containing up to 2.5 mol% I and synthesized under high pressure (0.5 to 1.5 GPa) have been investigated using differential scanning calorimetry (DSC). The I local environment in glasses has been determined using X-ray photoelectron spectroscopy and revealed that I is dissolved under its iodide form (I⁻). Results show that T_g is decreased with the I addition in the glass in agreement with previous results. We also observed that this T_g decrease is a strong function of glass composition. For NH, 2.5 mol% I induces a decrease of 24°C in T_g, whereas for ISG, 1.2 mol% decreases the T_g by 64°C. We interpret this difference as the result of the I dissolution mechanism and its effect on the polymerization of the boron network. The I dissolution in ISG is accompanied by a depolymerization of the boron network, whereas it is the opposite in NH. Although ISG corresponds to a standardized glass, for the particular case of I immobilization it appears less adequate than NH considering that the decrease in T_g for NH is small in comparison to ISG.     

2.3–21 GHz broadband and high linearity distributed low noise amplifier

This paper focuses on the design of a 2.3–21 GHz Distributed Low Noise Amplifier (LNA) with low noise figure (NF), high gain (S₂₁), and high linearity (IIP3) for broadband applications. This distributed amplifier (DA) includes S/C/X/Ku/K-band, which makes it very suitable for heterodyne receivers. The proposed DA uses a 0.18 μm GaAs pHEMT process (OMMIC ED02AH) in cascade architecture with lines adaptation and equalization of phase velocity techniques, to absorb their parasitic capacitances into the gate and drain transmission lines in order to achieve wide bandwidth and to enhance gain and linearity. The proposed broadband DA achieved an excellent gain in the flatness of 13.5 ± 0.2 dB, a low noise figure of 3.44 ± 1.12 dB, and a small group delay variation of ±19.721 ps over the range of 2.3–21 GHz. The input and output reflection coefficients S₁₁ and S₂₂ are less than −10 dB. The input compression point (P_1dB) and input third-order intercept point (IIP3) are −1.5 dBm and 11.5 dBm, respectively at 13 GHz. The dissipated power is 282 mW and the core layout size is 2.2 × 0.8 mm².     

Effect of Fe2+ and Fe0 Applied Photo‐Fenton Processes on Sludge Disintegration

The disintegration of waste active sludge was investigated by photo‐Fenton processes. A batch study was conducted to evaluate parameters, such as Fe²⁺ and Fe⁰ ions and H₂O₂, governing the activated sludge integration by the photo‐Fenton process. Under optimum conditions, the concentration of soluble chemical oxygen demand (SCOD) with the classical Fenton process (CFP) increased very rapidly in the first five minutes due to the sufficient presence of reaction components in the medium, and then the rate of increase declined. In the modified Fenton process (FTP), the SCOD concentration increased more slowly as metallic iron powder must first be dissolved. The photo‐Fenton process proved to be a feasible and efficient process for the disintegration of waste sludge.     

生物质基喷气燃料的生产及应用进展

生物质基喷气燃料是指全部或大部分来源于生物资源的喷气燃料，符合清洁低碳、安全高效的现代能源体系的要求。以生物质基喷气燃料替代传统石油基喷气燃料有助于我国早日实现“碳达峰、碳中和”的远大目标。在阐述生物质基喷气燃料生产工艺的发展历程及生物质基喷气燃料应用现状的基础上，提出高密度的生物质基喷气燃料是未来喷气燃料的发展方向，具有多环结构的生物质是合成高密度生物质基喷气燃料组分的优质原料；同时，总结了高密度生物质基喷气燃料组分生产工艺的研究进展，展望了生物质基喷气燃料未来的发展及挑战。     

An integrated dimensionality reduction and surrogate optimization approach for plant-wide chemical process operation

With liquefied natural gas becoming increasingly prevalent as a flexible source of energy, the design and optimization of industrial refrigeration cycles becomes even more important. In this article, we propose an integrated surrogate modeling and optimization framework to model and optimize the complex CryoMan Cascade refrigeration cycle. Dimensionality reduction techniques are used to reduce the large number of process decision variables which are subsequently supplied to an array of Gaussian processes, modeling both the process objective as well as feasibility constraints. Through iterative resampling of the rigorous model, this data-driven surrogate is continually refined and subsequently optimized. This approach was not only able to improve on the results of directly optimizing the process flow sheet but also located the set of optimal operating conditions in only 2 h as opposed to the original 3 weeks, facilitating its use in the operational optimization and enhanced process design of large-scale industrial chemical systems.     

Enhanced strains of Nb-doped BNKT-4ST piezoelectric ceramics via phase boundary and domain design

A strategy that constructs the morphotropic phase boundary and manipulates the domain structure has been used to design the component of 0.96[Bi_0.5(Na_0.84K_0.16)_0.5Ti_(1-x)Nb_xO₃]-0.04SrTiO₃ (BNKT-4ST-100xNb) to enhance the strain properties for actuator application. Non-equivalent Nb⁵⁺ donor doping modulates the phase transition from the mixture of rhombohedral and tetragonal phases to the pseudocubic phase and results in the coexistence of multiple phases. Moreover, the high-resolution TEM confirms the existence of polar nano regions that contribute to the macroscopic relaxor behaviour. The size of the domains is reduced with increasing Nb⁵⁺, resulting in an enhanced relaxor behaviour. The ferroelectric-relaxor transition temperature decreases from 85 to below 30 °C, implying a non-ergodic to ergodic relaxor transition. An improved strain of 0.56% and a giant normalized strain of 1120 pm/V were achieved for BNKT-4ST-1.5Nb, which were attributed to the unique domain structure in which nanodomains are embedded in an undistorted cubic matrix. Ferroelectric, antiferroelectric, and relaxor phases coexist. As the electric field is large enough, a reversible phase transition occurs. Furthermore, good temperature stability was obtained due to the stability of the nanodomains, and no degradation in strains was observed even after 10⁴ cycles, which may originate from the reversible phase transition and dynamic domain wall. The results show that this design strategy offers a reference way to improve the strain behaviour and that BNKT-4ST-100xNb ceramics could be a potential material for high-displacement actuator applications.     

Photo isomerization of cis-cyclooctene to trans-cyclooctene: Integration of a micro-flow reactor and separation by specific adsorption

Liquid-phase adsorption has hardly been established in micro-flow, although this constitutes an industrially vital method for product separation. A micro-flow UV-photo isomerization process converts cis-cyclooctene partly into trans-cyclooctene, leaving an isomeric mixture. Trans-cyclooctene adsorption and thus separation was achieved in a fixed-bed micro-flow reactor, packed with AgNO₃/SiO₂ powder, while the cis-isomer stays in the flow. The closed-loop recycling-flow has been presented as systemic approach to enrich the trans-cyclooctene from its cis-isomer. In-flow adsorption in recycling-mode has hardly been reported so that a full theoretical study has been conducted. This insight is used to evaluate three process design options to reach an optimum yield of trans-cyclooctene. These differ firstly in the variation of the individual residence times in the reactor and separator, the additional process option of refreshing the adsorption column under use, and the periodicity of the recycle flow.