Fabrication and characterization of nylon 6/foliated graphite electrically conducting nanocomposite

In this study, the nylon 6/foliated graphite (FG) electrically conducting nanocomposites with a low percolation threshold of less than 0.75 vol % have been prepared via an in situ polymerization approach in the presence of FG nanosheet filler. Based on laser counting, scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction characterization techniques, the structures and morphologies of the nanoscale filling particles and the resulting nanocomposites were examined. Using percolation theory, the conductivity behavior of the nanocomposite samples were modeled and analyzed. Through the use of mean‐field and excluded volume approaches, it was demonstrated that the experimentally observed percolation threshold values could be approximately estimated, and a correlation between the percolation threshold and the aspect ratio of FG particles could be quasi‐quantitatively established. Also, preliminary studies on the effects of FG nanosheets on the thermal properties of the host nylon 6 were performed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2844–2856, 2004     

In vivo characterization of 99mTc-spermine in mice bearing human breast cancer xenografts

The usability of ^99mTc-spermine for human breast tumor imaging was evaluated. Mice bearing MDA-MB-231 breast tumor were used for SPECT imaging and biodistribution study. Tumor was imaged clearly after injection with ^99mTc-spermine. The accumulation of ^99mTc-spermine was much lower in chest region than that of general breast tumor imaging agent ^99mTc-MIBI. It suggests that ^99mTc-spermine is promising for breast cancer imaging.     

螺杂环单羰基姜黄素类似物的合成、晶体结构与抗肿瘤活性研究

为了发现新型姜黄素类抗肿瘤先导化合物,通过1,3-偶极环加成反应合成了14个螺杂环单羰基姜黄素类似物.该反应利用无需加催化剂的"一锅煮"方法合成,具有环境友好的优点.所有化合物结构经ESI-MS、ESI-HRMS和1H NMR确认,通过X衍射确证B6的晶体结构为单斜晶系,该类化合物的合成具有良好的区域选择性和立体选择性.通过噻唑兰(MTT)法测定所有化合物对人胃癌细胞SGC-7901、神经胶质瘤细胞U251、人大细胞肺癌细胞株NCI-H460的增殖抑制活性,部分化合物表现出了较好的活性.其中B1、B6、B7和B11对三种肿瘤细胞均表现出较好的抗肿瘤活性,而对正常人肝细胞HL-7702显示了相对较低的细胞毒性.化合物B1和B7均能明显诱导凋亡相关蛋白含半胱氨酸的天冬氨酸蛋白水解酶3(caspase3)和多聚ADP-核糖聚合酶(PARP)的活化,诱导肿瘤细胞发生凋亡.所合成的螺杂环单羰基姜黄素类似物为新型的抗肿瘤化合物,该类化合物可能在靶向抗肿瘤药物研发方面具有较好的研究前景.     

立方Nd2O3上过氧物种光诱导生成的18O同位素示踪考察

采用原位显微Raman光谱和¹⁸O同位素示踪技术,以325 nm激光为激发光源,对立方Nd₂O₃上过氧物种的光诱导生成过程进行了详细表征,进一步证实过氧源于分子氧对晶格氧的氧化反应. 结果还表明,325 nm激光在室温下即可诱导过氧的生成,在实验条件下,生成的过氧物种可与Nd₂O₃的晶格氧发生快速的氧交换反应,位于Nd₂O₃体相的晶格氧也可迁移至样品表层进而参与过氧的生成. 325 nm激光照射有助于促进晶格氧的迁移以及晶格氧与分子氧之间的氧交换反应.     

Pt/Ce0.6Zr0.4O2催化剂催化氧化碳烟过程中活性氧对NO-NO2循环及表面含氧物种的分解作用简

通过在Ce_0.6Zr_0.4O₂载体上浸渍Pt（NO₃）₂制得Pt/Ce_0.6Zr_0.4O₂催化剂,该催化剂在松散接触条件下,于NO+O₂或O₂气氛中均表现出比Pt/Al₂O₃更好的碳烟氧化性能. 进一步研究表明,Pt/Ce_0.6Zr_0.4O₂催化剂中的Pt 与Ce_0.6Zr_0.4O₂存在相互作用,使得催化剂在一定温度范围内对活性氧的利用率大为提高,从而促进了气氛中NO↔NO₂的循环,乃至碳烟与NO₂的反应和碳烟表面含氧中间物种的生成;更重要的是,这部分活性氧本身可加速含氧中间物种的分解. 因此,在NO + O₂的气氛中,Pt/Ce_0.6Zr_0.4O₂催化剂的碳烟起燃温度比Pt/Al₂O₃降低了34 ℃.     

Study on thermal hazards for isoprene monomer (IPM) mixed with aluminum oxide

Isoprene monomer (IPM) is a colorless, volatile liquid obtained from petroleum or coal tar that occurs naturally in many process plants. It is used chiefly to make synthetic rubber. Our study used calorimetric approaches to conduct thermal analysis and hazard assessment of aluminum oxide (Al₂O₃) and IPM relevant studies. Differential scanning calorimetry, thermal activity monitor III, thermogravimetry, and vent sizing package 2 were used to discuss thermal instability reaction of Al₂O₃, which adsorbed IPM, and find every possible reason for cases of fire to prevent any future recurrence of the package store and transport related hazards. By means of calorimetric analysis technology, we can observe thermal decomposition or mass loss for different adsorbed concentrations of IPM and Al₂O₃ to discuss the related thermal stability parameters, such as exothermic onset temperature (T ₀), heat of decomposition (ΔH _d), self-accelerating exothermic rate (dT dt ^?1), pressure rise rate, and maximum reaction temperature (T _max). Then, we can understand the potential hazard factors that contribute to disasters related to processing, transport, and storage of security controls and reaction process design.     

Three New Pentacyclic Triterpenoids from Centella asiatica

Three new pentacyclic triterpenoids, named centellasaponin I ( 1 ), centellasaponin J ( 2 ), and centellasaponin E ( 3 ), together with three known compounds, were isolated from the whole plants of Centella asiatica. Their structures were elucidated on the basis of chemical and spectral analysis, including 1D‐ and 2D‐NMR and HR‐MS experiments, and by comparison with literature data.     

Elastic and Wearable Wire‐Shaped Lithium‐Ion Battery with High Electrochemical Performance

A stretchable wire‐shaped lithium‐ion battery is produced from two aligned multi‐walled carbon nanotube/lithium oxide composite yarns as the anode and cathode without extra current collectors and binders. The two composite yarns can be well paired to obtain a safe battery with superior electrochemical properties, such as energy densities of 27 Wh kg^?1 or 17.7 mWh cm^?3 and power densities of 880 W kg^?1 or 0.56 W cm^?3, which are an order of magnitude higher than the densities reported for lithium thin‐film batteries. These wire‐shaped batteries are flexible and light, and 97 % of their capacity was maintained after 1000 bending cycles. They are also very elastic as they are based on a modified spring structure, and 84 % of the capacity was maintained after stretching for 200 cycles at a strain of 100 %. Furthermore, these novel wire‐shaped batteries have been woven into lightweight, flexible, and stretchable battery textiles, which reveals possible large‐scale applications.     

Flexible and Stretchable Lithium‐Ion Batteries and Supercapacitors Based on Electrically Conducting Carbon Nanotube Fiber Springs

The construction of lightweight, flexible and stretchable power systems for modern electronic devices without using elastic polymer substrates is critical but remains challenging. We have developed a new and general strategy to produce both freestanding, stretchable, and flexible supercapacitors and lithium‐ion batteries with remarkable electrochemical properties by designing novel carbon nanotube fiber springs as electrodes. These springlike electrodes can be stretched by over 300 %. In addition, the supercapacitors and lithium‐ion batteries have a flexible fiber shape that enables promising applications in electronic textiles.     

Synthesis,characterization and crystal structure determination of mononuclear and dinuclear copper(II) carboxylates: [Cu(Hdpa)2(en)] and [{Cu2(μ-na)4(CH3OH)2}·2CH3OH]

Two new copper complexes [Cu(Hdpa)₂(en)] (1) and [{Cu₂(μ-na)₄(CH₃OH)₂}·2CH₃OH] (2) (where en is ethylene diamine, Hdpa is 2′-carboxy-[1,10-biphenyl]-2-carboxylate anion and na is 1-naphtalenecarboxylate) have been synthesized and their crystal structures were determined by X-ray crystallography. Complex 1 was prepared from the reaction of Cu(NO₃)₂·3H₂O with ethylene diamine and 2,2′-biphenyldicarboxylic acid in a mixture of water and methanol and complex 2 was prepared from the reaction of CuSO₄·5H₂O with 1-naphtalenecarboxylic acid in methanol. The two complexes were characterized by IR, UV–vis, luminescence and elemental analysis. Moreover, complex 2 was characterized by EPR spectroscopy and thermogravimetric analysis. Complex 1 is a monomer and complex 2 is a dimer with a paddle-wheel structure; both structures are without precedent in the literature.