An interval observer for uncertain continuous‐time linear systems

To design robust interval observers for uncertain continuous‐time linear systems, a new set‐integration approach is proposed to compute trajectory tubes for the estimation error. Because this approach, the order‐preserving condition on the dynamics of the estimation error is no longer required. Therefore, synthesis methods can be used to compute observer gains that reduce the impact of the system uncertainties on the accuracy of the estimated state enclosures. The performance of the proposed approach is showcased through illustrative numerical examples.     

高温固定流化床费托合成技术及其产物加工路线

与采用低温费托合成主产油品技术相比，产品更为多元化和高值化的高温费托合成技术在目前市场环境下显示出非常明显的优势。本文综述了高温费托合成技术的发展历程及其最新进展，重点介绍了高温费托合成过程中的核心问题，主要包括高温费托合成工艺、固定流化床反应器、费托合成催化剂；介绍了高温费托合成产物分布与特性，讨论了高温费托合成产物的加工路线，并对高温费托合成煤间接液化的工业应用前景和产业化方向进行了展望。结果表明：高温费托合成技术具有产物附加值高、兼顾油品和化学品、技术发展成熟等优势，产物中轻组分含量高、碳数分布较窄、高附加值的α-烯烃含量高；精细化、高端化、差异化加工是实现高温费托合成产物高值化利用的关键。     

Investigation of flame spray synthesized La1-xSrxCoO3 perovskites with promotional catalytic performances on CO oxidation

To enhance the activity of catalysts for CO removal, the perovskite-type catalysts La_1-xSr_xCoO₃ (x = 0, 0.2, 0.4, 0.6, and 0.8) with different Sr²⁺ doping amount were synthesized by flame spray synthesis (FSS) method. The perovskite-type catalyst synthesized by FSS has a much larger specific surface area (SSA) than that prepared by other conventional methods. The SSA of catalyst increases with the increase of Sr²⁺ doping amount and the SSA of La_0.2Sr_0.8CoO₃ reaches 31.65 m²/g. Compared with other conventional methods, FSS method significantly improves the activity of catalyst and makes it close to the performances of catalysts with surface modification. The substitution of La³⁺ by Sr²⁺ promotes the generation of secondary phase Co₃O₄ and SrCO₃. The catalytic activity of La_1-xSr_xCoO₃ increases with the addition of Sr²⁺, which results from the increasing active sites and oxygen vacancies. Interestingly, La_0.4Sr_0.6CoO₃ performs the highest activity for CO oxidation and the CO conversion reaches 50% at 148.6 °C and 90% at 165.9 °C. The oxidation of CO over La_1-xSr_xCoO₃ catalyst may follow a combination of MvK and L-H mechanisms according to the experimental results of H₂-TPR. Moreover, the catalyst exhibits good catalytic activity in consecutive oxidation cycles. In consecutive oxidation experiments with La_0.4Sr_0.6CoO₃, the CO conversion reaches 50% at 168.8 °C and 90% at 197.8 °C in the eighth oxidation cycle. These results prove that FSS method can further improve the activity of catalysts and is suitable for the preparation of efficient catalysts.     

Microstructure and Mechanical Properties of Cu Matrix Composites Reinforced byTiB2/TiN Ceramic Reinforcements

Cu matrix composites reinforced by TiB₂/TiN ceramic reinforcements (Cu/TBN composites) were prepared by hot pressing method. Prior to the hot pressing, Cu/TiB₂/TiN composite powders (CTBN powders), which were used as the starting materials of Cu/TBN composites, were fabricated by self-propagating high-temperature synthesis method. The CTBN particles were found to be in a special core-shell structure with a Cu-Ti alloy core and a TiB₂/TiN ceramic shell. The test results presented obvious improvements in mechanical properties. The highest ultimate tensile strength reached up to 297 MPa, 77 MPa higher than that of Cu. And the highest hardness reached up to 70.7 HRF, 15.7 HRF higher than that of Cu. A comparative study indicated that the core-shell structured particles could bring about more obvious strengthening effect than the traditional irregularly shaped particles, which was due to the improved Cu/ceramics interfacial bonding, the linkage strengthening effect of both TiB₂ and TiN, and higher load bearing ability of the core-shell structured reinforcements.     

Synthesis of high-entropy diboride nanopowders via molten salt-mediated magnesiothermic reduction

Powder synthesis is critical for implementing the wide applications of high-entropy diborides (HEBs). However, the low-temperature synthesis of HEB powders was rarely reported. Herein, the low-temperature synthesis of the single-phase HEB nanopowders via molten salt-mediated magnesiothermic reduction (MMR) method was reported for the first time. The results showed that the as-synthesized nanopowders consisted of the single-phase HEBs and their average particle sizes are in the range of 28-56 nm. Meanwhile, they possessed the good compositional homogeneity and the low-content oxygen impurity in the range of 4.13-6.12 at%. In addition, their formation mechanism could be well interpreted by a classical MMR growth process.     

The study of short-shot water-assisted injection molding of short glass fiber reinforced polypropylene

water penetration length and fiber orientation (along the melt flow direction) are important indicators for water-assisted injection molding products of the fiber-reinforced polymer. The effects of melt short shot size, water injection delay time and water injection pressure on these two important indexes are analyzed theoretically and experimentally. The study found that with the increase of the melt short shot size, the extension of the water injection delay time and the increase of the water injection pressure, the water penetration length changed from 216 to 96 mm, 170 to 210 mm, and 215 to 180 mm, respectively. Therefore, it can be known that melt short shot size has the greatest influence on water penetration length, followed by water injection delay time, and finally water injection pressure. Meantime, due to the fiber orientation and change degree of water-assisted injection-molded products along the melt flow direction, the fiber orientation in the water channel layer along the melt flow direction has the highest and lowest change degree, followed by the wall layer and finally the core layer. It can be known that the melt short shot size has the greatest influence on the fiber orientation and the degree of change along the melt flow direction, followed by the water injection delay time, and finally the water injection pressure.     

四种单萜类查尔酮的合成

以2, 4, 6-三羟基苯乙酮和柠檬醛为起始原料经过环化、羟醛缩合和催化加氢合成四种单萜类查尔酮;关键步骤2, 4, 6-三羟基苯乙酮和柠檬醛是在吡啶的催化下经过电子环化、质子迁移及Diels-Alder反应合成天然产物desbenzylidenerubramin (1),中间体1合成一种天然产物产物rubraine (2~5),其结构经~1H NMR和HREIMS表征。     

Facile approach for Z-scheme type Pt/g-C3N4/SrTiO3 heterojunction semiconductor synthesis via low-temperature process for simultaneous dyes degradation and hydrogen production

The platinum/graphite-like carbon nitride/strontium titanate (Pt/g-C₃N₄/SrTiO₃) heterojunction semiconductor was synthesized using a facile approach for simultaneous photocatalytic dye degradation and hydrolysis of hydrogen production from simulated dyeing wastewater. Using SrTiO₃, trace Pt, and the addition of an appropriate amount of electron donors, it can effectively absorb sunlight and achieve 93% dye degradation and 471 μmol h⁻¹ g⁻¹ hydrogen yield. The analysis result indicates that the semiconductor is a Z-scheme type composite. It was also showed that the addition of electron donors effectively promoted the degradation rate, whereas the addition of Pt changed the photocatalytic reaction pathway, which resulted in a reduced degradation rate and a significant improvement of hydrogen evolution. A reaction mechanism for this phenomenon is also proposed.     

Proton-Detected Solid-State NMR of the Cell-Free Synthesized α-Helical Transmembrane Protein NS4B from Hepatitis C Virus

Proton-detected 100 kHz magic-angle-spinning (MAS) solid-state NMR is an emerging analysis method for proteins with only hundreds of microgram quantities, and thus allows structural investigation of eukaryotic membrane proteins. This is the case for the cell-free synthesized hepatitis C virus (HCV) nonstructural membrane protein 4B (NS4B). We demonstrate NS4B sample optimization using fast reconstitution schemes that enable lipid-environment screening directly by NMR. 2D spectra and relaxation properties guide the choice of the best sample preparation to record 2D ¹H-detected ¹H,¹⁵N and 3D ¹H,¹³C,¹⁵N correlation experiments with linewidths and sensitivity suitable to initiate sequential assignments. Amino-acid-selectively labeled NS4B can be readily obtained using cell-free synthesis, opening the door to combinatorial labeling approaches which should enable structural studies.     

苯并噁嗪树脂的合成及在形状记忆聚合物中的应用研究进展

苯并噁嗪树脂作为一类新型的热固性树脂，具有分子设计性强、阻燃性能和耐腐蚀性能优异、固化时不需要强酸、无小分子放出等优点，在航空、建筑、电子等领域获得了广泛应用。本文主要介绍了苯并噁嗪单体的合成方法（溶剂法、无溶剂法和悬浮法）、降低苯并噁嗪开环聚合温度的方法（合成具有特殊基团的苯并噁嗪单体、添加催化剂）及苯并噁嗪树脂在形状记忆聚合物中的应用（与其他聚合物混合，纯苯并噁嗪化学改性），对苯并噁嗪形状记忆聚合物目前存在的问题进行了概述并对苯并噁嗪形状记忆聚合物的发展前景做出了展望。