乘用车悬架静强度与疲劳载荷研究

为了快速获得平台悬架静强度与疲劳载荷,本文依据某A级平台5款量产车型试验场道路栽荷数据,以前麦弗逊悬架为研究对象,先对轮心载荷幅值进行统计分析,根据应力-强度干涉模型,得到该平台前悬架的强度载荷边界,及其与车辆满载轮荷的G载荷系数.再通过研究5款车型车轮轮心疲劳伪损伤与轮荷的关联关系,得到该平台悬架的疲劳栽荷.此方法可快速获得同平台悬架静强度与疲劳载荷,省去实车道路谱采集并提升了工作效率.     

A Temperature‐Responsive Boronate Core Cross‐Linked Star (CCS) Polymer for Fast and Highly Efficient Enrichment of Glycoproteins

Fast and highly efficient enrichment and separation of glycoproteins is essential in many biological applications, but the lack of materials with high capture capacity, fast, and efficient enrichment/separation makes it a challenge. Here, a temperature‐responsive core cross‐linked star (CCS) polymer with boronate affinity is reported for fast and efficient enriching and separating of glycoproteins from biological samples. The temperature‐responsive CCS polymers containing boronic acid in its polymeric arms and poly(N‐isopropyl acrylamide) in its cross‐linked core are prepared using reversible addition‐fragmentation chain transfer polymerization via an “arm‐first” methodology. The soluble boronate polymeric arms of the CCS polymers provide a homogeneous reaction system and facilitate interactions between boronic acid and glycoproteins, which leads to a fast binding/desorption speed and high capture capacity. Maximum binding capacity of the prepared CCS polymer for horseradish peroxidase is determined to be 210 mg g^?1, which can be achieved within 20 min. More interestingly, the temperature‐responsive CCS polymers exhibit rapid reversible thermal‐induced volume phase transition by increasing the temperature from 15 to 30 °C, resulting in a facile and convenient sample collection and recovery for the target glycoproteins. Finally, the temperature‐responsive CCS polymer is successfully applied to enrichment of low abundant glycoproteins.     

Functional Characterization of 3-Aminobenzoic Acid Adenylation Enzyme PctU and UDP-N-Acetyl-d-Glucosamine: 3-Aminobenzoyl-ACP Glycosyltransferase PctL in Pactamycin Biosynthesis

Pactamycin is an antibiotic produced by Streptomyces pactum with antitumor and antimalarial properties. Pactamycin has a unique aminocyclitol core that is decorated with 3-aminoacetophenone, 6-methylsaliciate, and an N,N-dimethylcarbamoyl group. Herein, we show that the adenylation enzyme PctU activates 3-aminobenzoic acid (3ABA) with adenosine triphosphate and ligates it to the holo form of the discrete acyl carrier protein PctK to yield 3ABA-PctK. Then, 3ABA-PctK is N-glycosylated with uridine diphosphate-N-acetyl-d -glucosamine (UDP-GlcNAc) by the glycosyltransferase PctL to yield GlcNAc-3ABA-PctK. Because 3ABA is known to be a precursor of the 3-aminoacetophenone moiety, PctU appears to be a gatekeeper that selects the appropriate 3-aminobenzoate starter unit. Overall, we propose that acyl carrier protein-bound glycosylated 3ABA derivatives are biosynthetic intermediates of pactamycin biosynthesis.     

管壳式换热器内孔焊接残余应力特性研究

常规焊接会使管壳式换热器的换热管与管板之间形成一定的缝隙。换热器长期处于腐蚀性介质环境中,因此易产生缝隙腐蚀和应力腐蚀开裂,通过内孔焊接的方式可有效降低这类腐蚀风险。以Q245材料为研究对象,利用ABAQUS软件对焊接过程中温度场、应力场进行了模拟,研究了管壳式换热器内孔焊接的残余应力分布、设备变形情况,以及不同内孔焊结构残余应力和变形程度的差异,总结了焊接工艺参数对深孔焊接残余应力的影响规律。研究结果表明:全对接型接头的应力集中范围更小,设备应力分布更均匀、变形量较小,焊缝质量较高、承载能力较强。     

Enhanced relative permittivity in niobium and europium co-doped TiO2 ceramics

The appearance of colossal permittivity materials broadened the choice of materials for energy-storage applications. In this work, colossal permittivity in ceramics of TiO₂ co-doped with niobium and europium ions ((Eu_0.5Nb_0.5)_xTi_1-xO₂ ceramics) was reported. A large permittivity (ε_r ～ 2.01?×?10⁵) and a low dielectric loss (tanδ ～ 0.095) were observed for (Eu_0.5Nb_0.5)_xTi_1-xO₂ (x?=?1%) ceramics at 1?kHz. Moreover, two significant relaxations were observed in the temperature dependence of dielectric properties for (Eu, Nb) co-doped TiO₂ ceramics, which originated from defect dipoles and electron hopping, respectively. The low dielectric loss and high relative permittivity were ascribed to the electron-pinned defect-dipoles and electrons hopping. The (Eu_0.5Nb_0.5)_xTi_1-xO₂ ceramic with great colossal permittivity is one of the most promising candidates for high-energy density storage applications.     

Defect structure evolution and electrical properties of BaTiO3-based ferroelectric ceramics

Relaxor perovskite ferroelectric 0.1Bi(Zn_1/2Zr_1/2)O₃-0.9BaTiO₃(0.1BZZ-0.9BT) ceramics were successfully prepared, whose powders synthesized by the sol-gel process, with average grain size about 1.29 μm. 1.75 J/cm³ discharge energy density and good dielectric stability were obtained over a wide temperature range from 25°C to 140°C. The pulse discharge capability of 0.1BZZ-0.9BT ceramics was tested under different electric fields. The discharge time was 2.13 μs, which proved its ability to charge and discharge quickly. Complex impedance analysis and thermally stimulated depolarization current tests were applied to investigate the defect types and activation of 0.1BZZ-0.9BT ceramics. The evolution process of composite defects and oxygen vacancies profoundly affects the dielectric temperature stability of 0.1BZZ-0.9BT ceramics’ energy storage property.     

还原氧化石墨烯增强水泥基复合材料微观结构及力学性能

采用水热还原法制备了不同还原程度的还原氧化石墨烯(RGO),并将其添加到水泥浆体中,制得石墨烯增强水泥基复合材料。采用傅里叶变换红外光谱(FT-IR)、力学性能测试仪、扫描电子显微镜(SEM)对氧化石墨烯(GO)还原程度及水泥基复合材料的力学性能和微观结构进行测试。结果表明,在120℃水热条件下,控制不同还原时间可以得到不同还原程度的RGO;随着GO还原程度的提高,复合材料力学强度不断增加;RGO可使水泥更加密实,降低了水泥浆体的孔隙率,对水泥基复合材料起到增强增韧的作用。     

Effect of Fe/Zn ratio in composite catalyst for synthesizing polyoxymethylene dimethyl ethers

Polyoxymethylene dimethyl ethers (PODE_n) are extremely effective diesel additives to reduce soot formation during combustion. We introduce a series of Fe-Zn composite solid acid catalysts (SO₄²⁻/xFe₂O₃-yZnO), for the condensation reaction of methanol and paraformaldehyde (PF) with a cheap and feasible route to efficiently synthesize PODE_n. These catalysts were characterized by different characterization techniques, namely BET, XRD, SEM, EDS, FTIR, and NH₃-TPD and the results showed that Fe/Zn molar ratios strongly influenced the physicochemical characteristics of catalysts, thus affecting the methanol conversion and PODE_1-6 and PODE_3-6 selectivity. Accordingly, the methanol conversion was decreased and the selectivity of PODE_3-6 was increased after increasing the Zn molar content. Comparatively, SO₄²⁻/Fe₂O₃-2ZnO exhibited superior catalytic activity among the various investigated catalysts due to the high acid density of strong acid sites. The optimal reaction conditions were observed to be at a 3.0 wt% catalyst loading (catalyst/reactant mass ratio), 2.5 hours ours of reaction time, a reaction temperature of 403 K, and a molar ratio of 3:1 of CH₂O to methanol, achieving a high selectivity of 99.09% PODE_1-6 and 28.23% PODE_3-6 with 55.16% methanol conversion during the reaction.     

Plasmonic coupling-enhanced in situ photothermal nanoreactor with shape selective catalysis for C-C coupling reaction

Carbon-carbon (C-C) coupling reactions represent one of the most powerful tools for the synthesis of complex natural products, bioactive molecules developed as drugs and agrochemicals. In this work, a multifunctional nanoreactor for C-C coupling reaction was successfully fabricated via encapsulating the core-shell Cu@Ni nanocubes into ZIF-8 (Cu@Ni@ZIF-8). In this nanoreactor, Ni shell of the core-shell Cu@Ni nanocubes was the catalytical active center, and Cu core was in situ heating source for the catalyst by absorbing the visible light. Moreover, benefiting from the plasmonic resonance effect between Cu@Ni nanocubes encapsulated in ZIF-8, the absorption range of nanoreactor was widened and the utilization rate of visible light was enhanced. Most importantly, the microporous structure of ZIF-8 provided shape-selective of reactant. This composite was used for the highly shape-selective and stable photocatalysed C-C coupling reaction of boric acid under visible light irradiation. After five cycles, the nanoreactor still remained high catalytical activity. This Cu@Ni@ZIF-8 nanoreactor opens a way for photocatalytic C-C coupling reactions with shape-selectivity.