金属卤化物钙钛矿量子点的制备及其光催化应用研究进展

利用太阳能光催化技术生产清洁燃料、降解污染物及转化高附加值产品，是解决当前能源短缺和环境污染问题的有效途径。随着对金属卤化物钙钛矿的深入研究，成功开发出一系列能够制备出成分和形貌控制精确、产物均匀性好、结晶度高的钙钛矿量子点的合成方法，使钙钛矿量子点应用到光催化领域中。综述了热注入法、配体辅助再沉淀法、溶剂热法、微波辅助法等金属卤化物钙钛矿量子点的合成方法及金属卤化物钙钛矿量子点在光催化析氢、光催化还原二氧化碳、光催化合成有机物以及光催化降解有机物等方面的研究进展，最后对金属卤化物钙钛矿光催化剂的发展前景进行了展望。     

Gate Stacked (GS) Junctionless Nanotube MOSFET: Design and Analysis

Silicon - This paper presents Gate Stacked junctionless nanotube gate all around MOSFET (GS JL NT GAA MOSFET) and its investigation for low power circuit applications. In GS architecture, high-k...     

Research on steady characteristics of human-robot system for preventing elderly falls during walking

Due to the ever-increasing demand of caregivers and the high cost of nursing the elderly, researchers have been developing the elderly assistant robots (EARs) for assisting the elderly. To improve the safety of the elderly during walking, the steady characteristics of the EAR are discussed for preventing elderly falls during walking in this paper. Initially, the walking elderly was modeled as an inverted pendulum, and the steadiness region of the human and the general elderly fall conditions were obtained. The dynamics of the human-robot system were derived for preventing the general elderly falls. Also, the steadiness of the human and the robot were analyzed, respectively. Finally, experiments were conducted to verify the effectiveness of the models. The results demonstrated that the system met the requirements of steadiness, and hence, the designed robot could prevent elderly fall during walking. Thus, this study provides a theoretical basis for the effective control and the practical application of the EARs.

     

钻井液智能堵漏材料研究进展

钻井液智能堵漏材料已成为近年来石油开采领域的全新研究方向.与传统堵漏材料直接桥堵的方式不同,智能堵漏材料的特别之处在于拥有应对环境变化的能力,同时还具有针对性强、封堵效果突出、对地层损害小等特点.目前国内外关于智能堵漏材料的研究主要分为智能凝胶和形状记忆材料两个方向.其中,智能凝胶流动性相对较好,能够不受地层孔隙大小的影响,自适应能力强,可依据不同地层温度进行不同胶态间的转化,也可通过控制注入地层后凝胶的固结时间来提高封堵效率.相比之下,形状记忆材料的研究较多,包括形状记忆聚合物及形状记忆合金两种.形状记忆合金的延展性及抗疲劳能力比较突出,虽然形变量较小,但是承压能力强,易于形成网状结构,可明显提升桥堵作用,因此其封堵能力突出;形状记忆聚合物堵漏材料不仅形变量大,而且原料成本低,可保护储集层不受污染,能够有效应对复杂结构地层漏失问题.本文综述了钻井液智能堵漏材料的最新研究进展,尤其是对智能凝胶堵漏材料及形状记忆堵漏材料的研制方法、性能特点、应用情况等进行分析和总结,并对新型智能堵漏材料进行了介绍.     

Ceramics with eutectic microstructure in the ZrO2–PrOx system

Praseodymium oxides present redox properties analogous to those of Ce-based systems and have been proposed for catalytic applications in combination with CeO₂, ZrO₂, or both. However, uncertainties remain concerning the nature and redox behavior of Pr-rich mixtures, especially with ZrO₂. Here we study the eutectic composites of the ZrO₂–PrO_x system, focusing on the sensitivity of their microstructure, phase symmetry, and composition to variations of the processing atmosphere from oxidizing to reducing. Mixed oxides have been produced by a laser-assisted directional solidification technique in O₂, air, N₂, or 5%H₂(Ar) environment, and the resulting materials have been analyzed by scanning electron microscopy/energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, and magnetic susceptibility. In air, N₂, or 5%H₂(Ar) atmosphere, a lamellar, eutectic-like microstructure forms, the major phase being the one with less Pr content. Both the Pr concentration in each phase as the PrO_x molar percentage of the eutectic composites decrease as the atmosphere becomes more reducing. Both eutectic phases are fluorite-like when processing in air, whereas in N₂ or 5%H₂(Ar), the phase with high Pr content is of the A-R₂O₃ type, and the phase with low Pr content can be described as a fluorite phase containing C-R₂O₃-like short-range-ordered regions. The results obtained for samples processed in O₂ suggest that for high enough pO₂ no eutectic forms, in analogy with the ZrO₂–CeO₂ system. The evolution of the phase composition and symmetry is discussed in terms of the limited stability of the phases found in the ZrO₂–Pr₂O₃ system, namely, A- or C-R₂O₃-like, beyond a certain Pr oxidation degree and oxygen content.     

Boosting Sensitivity and Reliability in Field-Effect Transistor-Based Biosensors with Nanoporous MoS2 Encapsulated by Non-Planar Al2O3 (Adv. Funct. Mater. 42/2023)

Field-effect transistors-based biosensors (bio-FETs) have been considered an important technology for label-free and ultrasensitive point-of-care diagnostics. However, practical applications using bio-FETs are limited due to the trade-off between sensing reliability and sensitivity. This study suggests a reliable and sensitive bio-FETs based on nanoporous molybdenum disulfide (MoS₂) channels encapsulated by a non-planar high-k aluminum oxide (Al₂O₃) dielectric layer. Nanoporous MoS₂ thin film is fabricated with an abundant edge area and periodically ordered nanopores via block copolymer lithography. The ultra-thin Al₂O₃ dielectric layer deposited along the nanoporous structure of the MoS₂ realizes effective electrostatic control of charged biomolecules over the MoS₂ channel. In addition, it plays important roles in not only enhancing the electrical performance of the nanoporous MoS₂ bio-FETs, that is, mobility, hysteresis, and subthreshold swing, but also achieving effective biomolecular immobilization on the device surface. The nanoporous MoS₂ channel structure surrounded by non-planar Al₂O₃ detects a prostate cancer biomarker with an ultra-low limit of detection of 1 fg mL⁻¹. Moreover, the excellent selectivity, high sensitivity, and clinical reliability of the nanoporous MoS₂ bio-FETs are also confirmed. The proposed device platform provides new insights and technical advances in the field of FETs based sensors for future point-of-care devices.