液氧煤油发动机预冷系统回流管绝热影响分析

低温液体火箭发动机循环预冷受多因素影响,针对液氧煤油发动机自然循环系统回流管绝热条件对预冷效果的影响进行理论分析和试验研究,得到了有意义的数据和结论,对后续型号自然循环预冷系统设计提供了依据.     

Determination of absolute configuration of 2-methyl-1-(o-tolyl)naphthalene and the related axially chiral biaryls

An enantiomerically enriched sample (84.3% ee) of (aS)-2-methyl-1-[(((o-triisopropylsilyl)oxy)methyl)phenyl]naphthalene was produced via catalytic asymmetric Suzuki-Miyaura cross-coupling using an atropisomeric naphthamide-derived phosphine (A²phos) as the chiral ligand. After one recrystallization, enantiopurity of the biaryl product was improved to 98.9% ee and its absolute configuration was determined by X-ray crystal structural analysis. Through chemical transformations, the (aS)-enantiomers of 1-[(o-hydroxymethyl)phenyl]-2-methylnaphthalene, 1-[(o-chloromethyl)phenyl]-2-methylnaphthalene, and 2-methyl-1-(o-tolyl)naphthalene were obtained. Several other chiral biaryls were synthesized and stereochemically assigned.     

Solution-based synthesis of quaternary Cu-In-Zn-S nanobelts with tunable composition and band gap

We have demonstrated that quaternary Cu(x)In(x)Zn(2(1-x))S(2) nanobelts could be synthesized through a facile solution-based method. The composition and band gap of quaternary nanobelts can be tuned within the broad range by changing the relative ratio of precursors. The growth mechanism of quaternary nanobelts was deduced to be catalyst-assisted growth.     

高温超导电缆层电流分布对电缆稳态运行特性的影响分析

为了分析冷绝缘高温超导电缆层电流分布对其稳态运行特性的影响,提出超导电缆的等效电路模型,给出求解各层电流的矩阵方程,应用超导电缆的温度分布计算模型和边界条件,获得不同均流效果下的超导电缆最大载流能力和稳态径向温升,并与有限元计算结果进行对比。结果比较表明,各层电流均衡分布不仅能提高电缆的载流能力,而且可以降低超导电缆的稳态运行温升,提高了超导电缆在稳态运行时的稳定性。     

活性炭纤维耦合柠檬酸铁在中性pH条件下活化双氧水降解染料

在环境催化领域,开发pH适应范围广的类芬顿催化剂一直是活跃而极具挑战性的研究课题. 采用活性炭纤维耦合柠檬酸铁制得耐pH的类芬顿催化纤维(Cit-Fe@ACFs),在pH值2～10的范围内Cit-Fe@ACFs均表现出优异的催化性能,有效拓宽了传统芬顿反应的pH适应范围;Cit-Fe@ACFs在中性条件下能快速活化H₂O₂催化降解活性染料、酸性染料、碱性染料等多种染料,并具有良好的重复使用性. 采用探针化合物正丁醇、苯醌,结合电子顺磁共振波谱(EPR)证明了Cit-Fe@ACFs/H₂O₂催化体系中的氧化活性种主要为羟基自由基(·OH)和超氧自由基(HO₂·),推测了其催化反应机理.     

具有复合性能的新型三脚架型多苯并咪唑季铵盐类化合物的合成、表征和应用

合成了15种新型三脚架结构苯并咪唑季铵盐类化合物(3a~3o)。 通过IR、NMR和HRMS等技术手段对目标产物(3a~3o)进行了结构表征。 并对目标化合物调节植物生长活性进行了评价。 结果表明, 目标化合物浓度为10 mg/L时, 化合物3a、3c、3f、3g、3h、3i和3j均具有优良的促细胞分裂活性, 最高达88.3%, 比参照物三唑酮(50.2%)的促细胞分裂活性更高, 但生长素活性不明显;目标化合物均具有优异的除草活性, 其中化合物3i效果最明显, 可以达到95.6%。 同时利用荧光光谱, 探究了4种代表性目标分子对人体中常见的6种阴离子的荧光识别, 结果发现目标化合物能较好的识别I^- , 可作为I^-荧光识别探针。     

Experiment of passive ranging for three-sensor array in shallow water and post processing

For improving passive ranging of three-sensor array, a sliding cross-correlation method is adopted to improve the performance of time delay estimation. Compared with the traditional cross-correlation, the sliding cross-correlation＇s ability is evidently increased. An improved formula which is in high precision for near target is employed. An algorithm of kicking out wild value is presented, which is on line, can track the target automatically. The algorithm named ＂round filter＂ can pick out the data in high quality with robustness. A ＂dynamic filter＂ is presented, which is combined with the ＂round filter＂ as the post processor. The experimental result of three-sensor array passive ranging of near field target in shallow water is introduced, which suggests that the post processor is indeed obvious in improving the ranging performance.     

Characterization of Five Kinds of Wood Vinegar Obtained from Agricultural and Forestry Wastes and Identification of Major Antioxidants in Wood Vinegar

Wood vinegar(WV)has a powerful antioxidant activity,but it is unclear which components are responsible for the antioxidant activity.In the present study,the double-column retention index qualitative method was used for the identification of the major components in five kinds of W7 And the major antioxidants of wood vinegar were accurately identified with the aid of Pearson product-moment correlation coefficients and authentic standard samples. Our results demonstrate that phenolic compounds are mainly responsible for the powerful antioxidant activity. 2,6-Dimethoxyphenol is the most powerful antioxidant in WV.2-Methoxyphenol and 3-methyl-1,2-cyclopentanedioue also have an important influence on the antioxidant activity of WV.Our results suggest that the contents of 2-methoxyphenol,2,6-dimethoxyphenol and 3-methyl-1,2-cyclopentanedione should act as the criteria for evaluating the antioxidant activity of WV.Our work will provide useful information for WV's application in the fields of food and medicine as antioxidants.     

基于环形自由面岩土高效爆破的研究与应用

针对岩石巷道掘进循环进尺慢,炮孔利用率低的问题,采用取岩芯技术在岩土中形成环形自由面,利用少量炸药即可达到高效爆破的效果。首先对取岩芯爆破模型进行数值模拟,对爆炸效果进行预估,并得到相关爆破参数;之后根据模拟结果进行爆破实验,制作两组水泥模型,分别模拟取岩芯爆破与传统爆破,在模型外部布置测振仪,测量爆炸过后模型的相关振动数据,并对两组模型的爆破效果与振动数据作出比较,得出取岩芯模型爆破效果及爆破振动要明显优于传统爆破模型。最后将该技术应用在某岩巷掘进现场进行爆破实验,取得成功。实验结果表明,利用取岩芯技术成形环形自由面进行爆破, 可以减少炮孔数, 降低炸药单耗,控制住爆破振动,提高爆破效率,达到高效爆破的目的,特别是该技术可应用于城市地下工程爆破。     

Large‐Scale Modulation of Left‐Handed Passband in Hybrid Graphene/Dielectric Metasurface

Large‐scale modulation of the left‐handed transmission with a high quality factor is greatly desired by high‐performance optical devices, but the requirements are hard to be satisfied simultaneously. This paper presents a hybrid graphene/dielectric metasurface to realize a large transmission modulation for the left‐handed passband at near‐infrared frequencies via tuning the Fermi energy of graphene. By splitting the nanoblocks, i.e. introducing an additional symmetry breaking in the unit cell, the metasurface demonstrates an ultrahigh quality factor (Q ≈ 550) of Fano resonance with near‐unity transmission and full 2π phase coverage due to the interference between Mie‐type magnetic and electric resonances, which induces the negative refraction property. Besides, the split in the nanoblock greatly enhances the local field by increasing the critical coupling area, so the light‐graphene interaction is promoted intensively. When the surface conductivity of graphene is electrically tuned, the hybrid graphene/dielectric metasurface exhibits a deep modulation of 85% for the left‐handed passband, which is robust even for the highest loss of graphene. Moreover, the simple configuration remarkably reduces the fabrication requirements to facilitate the widespread applications.