1,3‐Dichloro‐tetra‐n‐butyl‐distannoxane: a new application for catalyzing the direct substitution of 9H‐xanthen‐9‐ol at room temperature

1,3‐Dichloro‐tetra‐n‐butyl‐distannoxane was firstly used to catalyze the direct substitution of 9H‐xanthen‐9‐ol with indoles at room temperature to afford a class of 3‐(9H‐xanthen‐9‐yl)‐1H‐indole derivatives in good to excellent isolating yield. Moreover, other nucleophiles (such as diketone and pyrrole) could also proceed smoothly in this methodology. Copyright © 2012 John Wiley & Sons, Ltd.     

Multifunctional triazolylferrocenyl Janus dendron: Nanoparticle stabilizer,smart drug carrier and supramolecular nanoreactor

Owing to their unique broken symmetry, amphiphilic Janus dendrimers and dendons provide fascinating properties for material, biological, pharmaceutical and biomedical applications. The integration of various organometallic moieties into these macromolecules will further offer the opportunity to form complex and intelligent architectures and materials. Here, we report a novel, simple and multifunctional Janus dendron containing redox‐reversible hydrophobic ferrocene (Fc) unit, complexing‐effective 1,2,3‐triazole ligand and biocompatible hydrophilic triethylene glycol termini. Silver and gold nanoparticles were firstly successfully prepared by using the Janus dendron as the reducing agent of Au(III) and Ag(I), and the stabilizer of the corresponding nanoparticles. The redox response of the Fc moiety was then employed to trigger the release of model drug, rhodamine B, encapsulated in supramolecular micelles formed by the self‐assembly of the Janus dendron. Finally, the precise and excellent metal‐complexing ability of the triazole group in this dendron was fully utilized to stabilize a water‐soluble Cu(I) catalyst, forming supramolecular nanoreactors for the catalysis of the copper(I)‐catalyzed azide alkyne cycloaddition click reaction in only water. The multifunctional characteristics of this dendron highlight the potential for organometallic Janus dendrimers and dendrons in the fields of functional materials and nanomedicines.     

涡流发生器污垢特性实验台的设计

为了研究涡流发生器的污垢特性设计了一个能够在线监测温度、流量以及压差进而可以直接得到污垢热阻的实验台。通过验证实验、准确性分析与误差分析,验证了实验台设计精度在允许的误差范围内。示例实验结果表明实验台具有研究涡流发生器的污垢特性、压力特性以及换热特性的功能。     

基于毛竹叶片理化参数的刚竹毒蛾危害检测研究

虫害检测算法研究是开展虫害快速、准确监测，制定精准森防检疫措施的重要基础。以毛竹叶片为研究尺度，基于刚竹毒蛾危害下的寄主外部形态与内部生理现象总结，选择并实测叶损量LL、相对叶绿素含量RCC、相对含水量RWC、原始光谱的733.66~898.56 nm值(ρ_{733.66~898.56})、一阶微分光谱的562.95~585.25 nm值(ρ′_{562.95~585.25})与706.18~725.41 nm值(ρ′_{706.18~725.41})等理化参数，随机划分实验组(63组)和验证组(37组)并设计5次重复实验；分别运用Fisher判别分析、BP神经网络、随机森林等三种方法建立刚竹毒蛾危害等级的检测模型，从检测精度、Kappa系数及R2等指标对模型的检测效果予以分析和比较。结果显示，Fisher判别分析、BP神经网络、随机森林的检测精度分别为69.19%，65.41%，83.78%，Kappa系数分别为0.576 9，0.532 4和0.778 8，R2分别为0.722 2，0.582 6和0.870 9，总体而言，三种方法均具备刚竹毒蛾危害的检测能力，随机森林的检测效果最优，Fisher判别分析次之，再次为BP神经网络；从分等级来看，随机森林的检测精度亦优于Fisher判别分析与BP神经网络，但3种方法对中度危害等级的检测精度均有所不足。该成果可为刚竹毒蛾危害及其他病虫害检测算法的选择提供参考，并为进一步建立冠层、遥感影像像元等尺度的虫害检测模型奠定基础。     

Rational Synthesis of Iron/Nitrogen-Doped Carbon Catalyst through a Spatial Isolation Strategy for Efficient Oxygen Reduction in Acidic and Alkaline Media

It remains challenging to rationally synthesize iron/nitrogen-doped carbon (Fe/N-C) catalysts with rich Fe−N_x atomic active sites for improved oxygen reduction reaction (ORR) electrocatalysis. A highly efficient Fe/N-C catalyst, which has been synthesized through a spatial isolation strategy, is reported. Derived from bioinspired polydopamine (PDA)-based hybrid microsphere precursors, it is a multifunctional carrier that loads atomically dispersed Fe³⁺/Zn²⁺ ions through coordination interactions and N-rich melamine through electrostatic attraction and covalent bonding. The Zn²⁺ ions and melamine in the precursor efficiently isolate Fe³⁺ atoms upon pyrolysis to form rich Fe−N_x atomic active sites, and generate abundant micropores during high-temperature treatment; as a consequence, the resultant Fe-N/C catalyst contains rich catalytically active Fe−N_x sites and a hierarchical porous structure. The catalyst exhibits improved ORR activity that is superior to and close to that of Pt/C in alkaline and acidic solutions, respectively.     

化学模拟在反应堆水化学课程中的应用

高温高压化学反应对反应堆设备的可靠性、反应堆性能的控制、核电站运行的安全持久性等具有重要影响，但相关实验难以在高校教学中开展。借助PHREEQC程序及最新热力学数据，建立了反应堆一回路硼酸-氢氧化锂添加配比、腐蚀沉淀物产生及二回路pH控制方案的化学反应模型。运用化学模拟来教学，促进了学生对所学知识的理解与掌握，丰富了现代教学方法。相关模型对核电企业的培训也具有一定参考价值。     

实验室安全环保意识的调查与分析——以中山大学化学类专业学生为例

A survey about students' laboratory safety and environmental protection consciousness was performed in the freshmen majored in chemistry at Sun Yat-Sen University. Results showed that laboratory safety and environmental protection consciousness of most students' are weak. After analyzing the reasons, we put forward some suggestions. Cultivating students' laboratory safety and environmental protection consciousness should be carried out from several aspects such as emphasizing and regulating from school level, training in laboratory teaching, maintaining good cultural atmosphere of laboratory, as well as providing perfect laboratory safety and environmental protection facilities. We should guide students to actively learn knowledge and skills of laboratory safety and environmental protection in order to develop their good behavior and raise their consciousness.     

Thermal-oxidative degradation of high-amylose corn starch

Thermal oxidation degradation of high-amylose (80 %) cornstarch has been studied using thermogravimetry analyser coupled to Fourier transform infrared spectroscopy (TG-FTIR). The linear structure of amylose provides a modal material to understand how the starch microstructure affects on the decomposition mechanisms. Kinetics of the thermal oxidation has been studied using different methods. It is found that the thermal oxidation degradation is more complex than thermal degradation, thermal oxidation degradation kinetics of the starch can be interpreted in terms of multi-step degradation mechanism, the activation energies obtain from Flynn–Wall–Ozawa (F–W–O) method and modified Coats–Redfern method are in good agreement. TG-FTIR and FTIR results confirm that the thermal oxidation mechanism of starch is a process containing long chain scission and glowing combustion.     

Filling the Charge–Discharge Voltage Gap in Flexible Hybrid Zinc-Based Batteries by Utilizing a Pseudocapacitive Material

The high charge–discharge voltage gap is one of the main bottlenecks of zinc–air batteries (ZABs) because of the kinetically sluggish oxygen reduction/evolution reactions (ORR/OER) on the oxygen electrode side. Thus, an efficient bifunctional catalyst for ORR and OER is highly desired. Herein, honeycomb-like MnCo₂O_4.5 spheres were used as an efficient bifunctional electrocatalyst. It was demonstrated that both ORR and OER catalytic activity are promoted by Mn^IV-induced oxygen vacancy defects and multiple active sites. Importantly, the multivalent ions present in the material and its defect structure endow stable pseudocapacitance within the inactive region of ORR and OER; as a result, a low charge–discharge voltage gap (0.43 V at 10 mA cm⁻²) was achieved when it was employed in a flexible hybrid Zn-based battery. This mechanism provides unprecedented and valuable insights for the development of next-generation metal–air batteries.     

环路跟踪卡尔曼滤波算法的性能分析

基于卡尔曼滤波的环路跟踪算法多是通过一定仿真证明算法性能,没有系统性性能评估,难以较好指导工程应用。在原有算法基础上进行了优化,并系统性地对比分析、评估了基于卡尔曼环路滤波算法性能,以期为算法工程化提供指导。首先提出对跟踪环路反馈调整量进行预测,使之更符合系统实际,减小环路跟踪误差。而后基于卫星信号模拟器输出信号和自生产信号源,充分评估基于卡尔曼滤波环路跟踪算法的收敛时间和灵敏度。仿真结果表明,相比目前工程常用的二阶FFL辅助三阶PLL算法,基于卡尔曼滤波环路跟踪算法能够缩短环路所需稳定时间约90%,并能提升跟踪灵敏度约5 d B,有效改善弱信号场景中接收机输出信息的完好性和连续性。