Facile construction of highly efficient MOF-based Pd@UiO-66-NH2@ZnIn2S4 flower-like nanocomposites for visible-light-driven photocatalytic hydrogen production

Construction of metal-organic-frameworks-based composite photocatalysts has attracted much atten-tion for the reasonable band gap and high surface areas to improve the photocatalytic activity.In this study,the ternary heterojunction Pd@UiO-66-NH2@Znln2S4 nanocomposites were facilely prepared for the first time by a two-step method.The visible-light-promoted hydrogen production rate of 0.3％ Pd@UiO-66-NH2@Znln2S4 reaches up to 5.26 mmol g-1 h-1,which is evidently much higher than pure UiO-66-NH2,ZnIn2S4 and binary UiO-66-NH2/ZnIn2S4 composites.Such a huge improvement in the pho-tocatalytic performance is mainly attributed to the matched band gap of ZnIn2S4 and UiO-66-NH2,and the introduction of Pd NPs into photocatalysts that broaden spectral response range and promote the photon induced charge carrier separation.This work may provide a feasible approach for the design and construction of metal-organic-frameworks-based photocatalytic materials.     

白术多糖介孔二氧化硅的制备及其对小鼠巨噬细胞吞噬能力的影响

目的：建立一种具有抗乳腺增生作用的白术多糖（Atractylodes macrocephala Koidz polysaccharide,AMP）硫酸酯的制备方法。方法：采用浓硫酸法对AMP进行硫酸化修饰（sulfated polysaccharides from Atractylodes macrocephala Koidz,SAMP）,通过响应面法确定硫酸酯化反应最佳工艺条件;采用高效凝胶渗透色谱法（HPGPC）、红外光谱法（IR）对AMP及SAMP的结构进行初步鉴定;通过测定AMP与SAMP对DPPH、ABTS⁺、OH自由基清除能力,考察其体外抗氧化活性;通过苯甲酸雌二醇-黄体酮联用建立大鼠MGH模型,记录大鼠体重及乳房直径,观察大鼠乳腺病理组织形态。结果：最佳工艺条件为反应试剂比（浓硫酸:正丁醇）=2:1,反应温度−4 ℃,反应时间21 min,在此条件下SAMP取代度为0.59±0.00391。HPGPC测定结果显示AMP、SAMP分子质量分别为2719、33524 Da;红外光谱显示SAMP在833、1226 cm⁻¹出现C-O-S和S=O特征吸收峰,表明AMP修饰成功;当多糖溶液质量浓度为0.5 mg/mL时,SAMP对DPPH、ABTS⁺、OH自由基清除率分别为54.91%、38.21%、42.23%。同模型组比较,SAMP组大鼠乳头直径减小（P<0.01）,乳腺腺泡数量减少,乳腺增生症状减轻,且SAMP治疗效果优于AMP。结论：响应面法优化AMP硫酸酯化工艺方法稳定可行,且AMP经硫酸酯化修饰后,具有更好的抗乳腺增生作用。     

一种基于Burg谱估计和FFT的频偏估计方法

针对星间链路通信中常用的BPSK、QPSK、UQPSK和64QAM等调制信号的载波频偏估计问题,提出了一种基于Burg谱估计和FFT的通用频偏估计方法。采用Burg谱估计方法对信号进行粗频偏估计,补偿该频偏后得到含有较小残留频偏的信号;并进行改进的四次方非线性变换,去除调制信息;再利用FFT估计出较高精度的残留频偏值。仿真结果表明,该方法估计精度高、范围大。     

Effect of single water adsorption on the bond order of calcium silicates and its implication for hydration variation

The differences in hydration between β-C₂S and M3-C₃S, the main phases of silicate cement, have not been fully investigated. In this study, density functional theory calculations were used to investigate the structure and bond order of β-C₂S and M3-C₃S before and after the molecular and dissociative adsorption of single water atoms. The unit cell of M3-C₃S was found to have some O atoms with lower bond orders than those in β-C₂S, implying higher chemical reactivity of O atoms in M3-C₃S. The total bond orders of water atoms generally decreased after molecular adsorption, but reductions were minimal, and there were even increases, when the hydrogen bonding among H and surface O atoms was very weak in several M3-C₃S surfaces. In the case of dissociative adsorption, the bond orders of water O–H hydroxyl tended to increase, and the other bond orders among water atoms decreased sharply, even to zero in some cases. Moreover, the bond order variations of water atoms of β-C₂S and M3-C₃S in molecular adsorption were highly correlated with the adsorption energy, with correlation coefficients of 0.9070 and 0.8330, respectively. In both molecular and dissociative adsorption of β-C₂S and M3-C₃S, the total bond order among Ca atoms with other surface atoms decreased after the Ca atoms adsorbed water atoms. This phenomenon also appeared in the dissociative adsorption of surface O atoms. In M3-C₃S, the total strength of the surface O atom bonded to other surface atoms after dissociative adsorption was similar to the strength of the surface O–H hydroxyl bond. The special O atoms in M3-C₃S showed a clear layered arrangement on the surfaces. In the case of dissociative adsorption, H atoms were preferentially adsorbed to special O atoms in the surface layer.     

固定翼垂直起降无人机过渡机动优化控制分配研究

以一种固定翼垂直起降无人机为研究对象,研究其6自由度过渡机动非线性优化控制分配问题。基于增量动态逆（INDI）方法设计全局化控制器,并利用该方法降低控制模型中的不确定性对控制效果的影响。针对无人机控制冗余和耦合问题,在INDI基础上提出一种2级递进式优化控制分配方法,对航迹和姿态控制回路中的控制变量增量进行综合优化分配。该优化控制分配方法可以将非线性耦合控制分配问题转化为线性优化问题求解,避免了迭代计算,同时提高了求解速率。针对优化分配中的目标函数设计动态权值选取方案,使无人机能够根据任务需求和飞行状态调整优化分配侧重方向并确保优化结果的合理性。仿真结果表明,该无人机能够很好地跟踪过渡机动航迹,控制分配方法可行。     

熔炼工艺和增强相含量对Sn基复合钎料显微组织的影响

分别研究了不同冷却速率和增强相添加量对内生法制备的Cu6Sn5颗粒增强型复合钎料以及Ni颗粒增强复合钎料显微组织的影响,并得出最佳的冷却工艺条件。结果表明:空冷条件(冷却速率为2℃/s)下制备的Cu6Sn5颗粒增强型复合钎料拥有最佳的显微组织形貌特征,其金属间化合物(IMC)尺寸最小,分布最均匀。对于外加法制备的Ni颗粒增强型复合钎料,其内部大尺寸IMC对周边三元共晶组织生长方向产生严重影响。此外,值得注意的是,当Ni质量分数为0.45%时,显微组织中出现了由IMC聚集形成的树叶和雪花形态。当Ni质量分数增加至2.0%时,由于Ni元素在钎料基体中固溶的作用,显微组织中出现了均匀分布的形状和大小不一的黑色斑点。     

脂肪酸甲酯的合成及综合应用

脂肪酸甲酯作为一种新型环保可再生资源而受到广泛的关注。分析介绍了脂肪酸甲酯在不同领域的应用。重点阐述了脂肪酸甲酯在表面活性剂、树脂的合成、农药助剂方面以及化工领域方面的应用。同时,还介绍了合成脂肪酸甲酯的制备工艺及催化方法,包括传统液体酸碱催化、固体酸碱催化剂、离子液体催化、生物酶催化及新型催化技术。     

Boosting the capacitance of NiCo2O4 hierarchical structures on nickel foam in supercapacitors

A facile method of directly growing NiCo₂O₄ hybrid hierarchical nanostructures on nickel foam is developed by a hydrothermal and post heat-treatment method without using any surfactant, stabilizer or organic binder. Due to the rich porous nanostructures, relative large specific surface area (177.71 m² g^?1) of the NiCo₂O₄ hybrid structure and efficient electrical contact with the conductive nickel substrate, the NiCo₂O₄NF hybrid electrode shows significantly enhanced specific capacitance (3105.1 F g^?1 at 1 A g^?1), outstanding rate properties (1621.3 F g^?1 at 20 A g^?1 and 1191.5 F g^?1 at 50 A g^?1) and high energy density (95.26 Wh kg^?1). This facile and effective design method opens up new possibilities for producing binder-free electrodes in high-performance electrochemical supercapacitors and miniaturized devices.     

线性聚醚嵌段氨基硅油的制备及其性能

为简化线性嵌段聚醚氨基硅油的合成工艺,以双端氨基聚醚与双端环氧基聚醚硅油为反应单体,异丙醇为溶剂,通过开环聚合一步反应制备线性嵌段聚醚氨基硅油(LEPS),并将其应用于羊绒针织物的柔软整理。借助傅里叶变换红外光谱仪、热重分析仪、多功能表面分析电子能谱仪与扫描电子显微镜等表征LEPS及其整理织物的理化性能。结果表明:当2种反应单体的量比为1:1,所得LEPS氨值为0.14 mmol/g、摩尔质量为 7.39×10 ⁴ g/mol,其乳液的稳定性能优良;LEPS整理织物手感达到5级,柔软、蓬松性能突出,并且织物的亲水、透湿与抗静电性能良好,黄变程度低;LEPS的综合性能优良,制备工艺简单。