背景磁场下Y系超导带材临界电流的测量

高温超导电力装置一般工作于低磁场情况下,测量超导带材在低场下的临界电流特性非常重要.文中通过自行设计的实验平台,采用四引线法对Y系超导带材低场下的临界电流特性进行了测量,得到了带材临界电流随外加磁场变化的曲线,并与Bi系带材低场下的临界电流特性进行比较.     

黄河河道冰水情定点连续自动检测及数据分析

根据黄河中上游流域冰水情监测以及预防凌汛灾害的需求,设计了一种适合黄河河道的冰水情自动测报系统.该系统由基于空气、冰与水电阻特性差异的冰层厚度传感器、DS18B20的温度梯度传感器以及智能处理仪构成.采用该系统在内蒙托克托县黄河河道进行了黄河封冻期河道冰层厚度连续监测试验,获取了大量的现场实测数据,对采样数据进行分析,提出了判别冰层厚度的平均滤波算法,实现了对冰层生消变化全过程的自动监测.     

锂离子电池纳米结构正极材料LiV3O8的制备及性能

采用水热合成方法,在不同水热合成温度下制备了具有纳米结构的锂离子电池正极材料LiV3O8。并利用X射线衍射、透射电镜、恒流充放电、循环伏安以及电化学交流阻抗等测试手段对其结构、形貌和性能做了研究。结果表明,不同的水热合成温度影响到产物的结构、形貌和性能。随着水热温度的升高,粒子的直径随之增大,而形貌和尺寸的均一性则有所降低。电化学测试结果表明水热180℃得到产物的比容量较高,具有良好的电化学可逆性,而且随着水热温度的升高,材料的电荷转移电阻依次减小,有利于锂离子的嵌入与脱出,比容量也随之增加。可见材料的结构中存在一定的非晶缺陷,以及粒子具有一定范围内的尺寸分布,对材料的电化学性能有改善作用。     

配送量不定的供应链协调

本文研究供应链管理中配送量不确定时，制造商和分销商之间的协调问题。通过建立惩罚和奖励机制模型来协调供应链各部分的运作，使得分散系统就如一个整体。同时分析供应链的利润分配问题，分别得出各个机制下分销商的最优决策。     

Bis(<Emphasis Type="Italic">β</Emphasis>-cyclodextrin)s Linked with an Aromatic Diamine as Fluorescent Sensor for the Molecular Recognition of Bile Salts

The binding behavior of three aromatic diamino-bridged bis(β-cyclodextrin)s (2–4) with four bile salts {cholate (CA), deoxycholate (DCA), glycocholate (GCA) and taurocholate (TCA)} has been investigated at 25 °C in a phosphate buffer (pH=7.20) by fluorescence and 2D NMR spectroscopy. The results indicate that these bis(β-cyclodextrin)s act as fluorescent sensors. From the ROESY spectra, it is deduced that the phenyl moieties of bis(β-cyclodextrin)s 2–4 are partially self included in the cyclodextrin cavity, and are not expelled from the cavity upon complexation with bile guests. Owing to the cooperative host-tether-guest binding mode in which the linker and guest are co-included in the two cyclodextrin cavities, these bis(β-cyclodextrin)s significantly enhance the binding ability and selectivity as compared with the native β-cyclodextrin 1. Possessing suitable tether length, bis(β-cyclodextrin) 3 gives the highest K _S values, ranging up to 39,900 mol⋅L⁻¹, for complexation with CA. The complex stability constants are discussed from the viewpoint of multiple recognitions between host and guest.     

DNA intercalating studies of [Ru(bpy)<Subscript>2</Subscript>HPIP]<Superscript>2+</Superscript> with intramolecular hydrogen bond ligand based on introduction of copper ion

The effects of copper ion on the interaction of [Ru(bpy)₂HPIP]²⁺(bpy = 2,2′-bipyridine, HPIP = 2-(2-hydroxyphenyl) imidazo [4,5-f] [1, 10] phenanthroline) with DNA have been investigated by electronic absorption spectroscopy and fluorescence spectroscopy. HPIP ligand of the complex with an intramolecular hydrogen bond can bind Cu²⁺ in the absence of DNA, as revealed by the absorbance and fluorescence decrease for [Ru(bpy)₂HPIP]²⁺. The resultant heterometallic complex binds to DNA via intercalation of HPIP into the DNA base pairs and its DNA-binding ability is stronger than [Ru(bpy)₂HPIP]²⁺ itself. The DNA bound [Ru(bpy)₂HPIP]²⁺ cannot bind Cu²⁺ at low Cu²⁺ concentration and the intramolecular hydrogen bond in HPIP is located inside the DNA helix. While the Cu²⁺ concentration is relative high, Cu²⁺ can quench the fluorescence of DNA bound [Ru(bpy)₂HPIP]²⁺. The quenching reason is proposed.     

地西泮半抗原衍生物的合成

以2-氨基-5-氯二苯甲酮和氯乙酰氯为原料,经酰胺化、六亚甲基四胺关环、硫酸二甲酯甲基化、引入丁酸叔丁酯和三氟乙酸水解等5步反应,设计并合成了一种地西泮半抗原衍生物,其结构经1 H NMR,13 C NMR和MS（ESI）表征。     

Determination of 12 additives in beverages by evaporation-assisted dispersive liquid-liquid microextraction based on the solidification of floating organic droplets combined with liquid chromatographyEI北大核心CSCD

An analytical method for the simultaneous determination of 12 additives in beverages was developed using evaporation-assisted dispersive liquid-liquid microextraction based on the solidification of floating organic droplets EVA-DLLME-SFOcombined with high performance liquid chromatography HPLC. The samples were extracted twice with 70%V/Vmethanol aqueous solution and extracted by EVA-DLLME-SFO method after the combination of the extractsand finally determined by HPLC. Extraction parameterssuch as types and amounts of extractantevaporant and heating agentthe concentration of saltand the extraction time were optimized. Under the optimized conditionsthere were good relationships in the ange of 0.25-50 μµg/mL with the limits of detection of 1.5 to 13.6 mg/kg and limits of quantification of 5.2 to 45.3 mg/kg. The recoveries at three spiked levels1025 and 50 mg/kgwere 76.8% to 101.2% with the relative standard deviations of 0.11% to 4.7%. The method can be used for rapid detection of 12 additives in beverages. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

七元瓜环对阿糖胞苷稳定性的影响

研究了七元瓜环(Q[7])与抗癌药物阿糖胞苷(Ara-C)的不同质子化存在形式之间的超分子相互作用, 探讨了超分子包合作用对药物电离平衡常数及药物稳定性的影响. 结果表明, Q[7]使得Ara-C的pK_a降低了约0.3个单位, Q[7]与Ara-C的2种存在形式(Ara-C⁺及Ara-C)均可形成1∶1的主客体包结配合物, Ara-C以其嘧啶环进入Q[7]空腔, 而核糖环位于瓜环端口发生相互作用; Q[7]与Ara-C作用后对药物起到保护性载体的作用, 从而提高了药物的稳定性.     

Diamondoid Nanostructures as sp3‐Carbon‐Based Gas Sensors

Diamondoids, sp³‐hybridized nanometer‐sized diamond‐like hydrocarbons (nanodiamonds), difunctionalized with hydroxy and primary phosphine oxide groups, enable the assembly of the first sp³‐C‐based chemical sensors by vapor deposition. Both pristine nanodiamonds and palladium nanolayered composites can be used to detect toxic NO₂ and NH₃ gases. This carbon‐based gas sensor technology allows reversible NO₂ detection down to 50 ppb and NH₃ detection at 25–100 ppm concentration with fast response and recovery processes at 100 °C. Reversible gas adsorption and detection is compatible with 50 % humidity conditions. Semiconducting p‐type sensing properties are achieved from devices based on primary phosphine–diamantanol, in which high specific area (ca. 140 m² g^?1) and channel nanoporosity derive from H‐bonding.