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101.
Li-Ming?Lo Candace?S.-J.?TsaiEmail author William?A.?Heitbrink Kevin?H.?Dunn Jennifer?Topmiller Michael?Ellenbecker 《Journal of nanoparticle research》2017,19(8):293
This site study was conducted in a chemical laboratory to evaluate nanomaterial emissions from 20–30-nm-diameter bundles of single-walled carbon nanotubes (CNTs) during product development activities. Direct-reading instruments were used to monitor the tasks in real time, and airborne particles were collected using various methods to characterize released nanomaterials using electron microscopy and elemental carbon (EC) analyses. CNT clusters and a few high-aspect-ratio particles were identified as being released from some activities. The EC concentration (0.87 μg/m3) at the source of probe sonication was found to be higher than other activities including weighing, mixing, centrifugation, coating, and cutting. Various sampling methods all indicated different levels of CNTs from the activities; however, the sonication process was found to release the highest amounts of CNTs. It can be cautiously concluded that the task of probe sonication possibly released nanomaterials into the laboratory and posed a risk of surface contamination. Based on these results, the sonication of CNT suspension should be covered or conducted inside a ventilated enclosure with proper filtration or a glovebox to minimize the potential of exposure. 相似文献
102.
Yang LM Ravindran P Vajeeston P Tilset M 《Physical chemistry chemical physics : PCCP》2012,14(14):4713-4723
The chemical bonding, electronic structure, and optical properties of the experimentally available metal-organic framework IRMOF-14 and its metal-substituted analogues M-IRMOF-14 (M = Zn, Cd, Be, Mg, Ca, Sr, Ba), which contain a pyrene-2,7-dicarboxylate linker group, have been systematically investigated using DFT calculations. The unit cell volume and atomic positions were optimized with the Perdew-Burke-Ernzerhof (PBE) functional and showed good agreement between experimental and theoretical equilibrium structural parameters for Zn-IRMOF-14. The calculated bulk moduli indicate that the whole M-IRMOF-14 series are soft materials. The estimated band gap from DOS calculations for the M-IRMOF-14 series is ca. 2.5 eV, essentially independent of the metal ion and indicative of nonmetallic character. The band gap value is distinctly different from those calculated previously for the M-IRMOF-1 (benzene-1,4-dicarboxylate linker; ca. 3.5 eV) and M-IRMOF-10 (biphenyl-4,4'-dicarboxylate linker; ca. 3.0 eV) series and this confirms that the identity of the linker is a key parameter to control band gaps in an isoreticular series of main-group MOFs. In view of potential uses of MOFs in organic semiconducting devices such as field-effect transistors, solar cells, and organic light-emitting devices, the linear optical properties of these materials were also investigated. Comparisons are made with the M-IRMOF-1 and M-IRMOF-10 series. 相似文献
103.
104.
Yi-Zhen Wang Guan-Hai Wang Xiao-Min Xiong Biao Wang Li-Ming Zhang Jin-Xiu Zhang 《Rheologica Acta》2010,49(11-12):1117-1126
Traditional torsional resonators, often obtaining the viscoelastic moduli of complex fluids only at one or several given discrete frequencies, lack the continuously varying frequency capability. This is an obvious disadvantage of the traditional torsional resonator technique. This paper presents an improved strategy, based on our previous discrete-frequency-measuring method (Wang et al., J Rheol 52:999–1011, 2008), to overcome such restriction and thus accomplish the continuously varying frequency capability of the traditional torsional resonator for measuring the viscoelastic properties of complex fluids. The feasibility of this strategy is demonstrated with the Newtonian fluids (several water–glycerol solutions) of viscosities varying from 10 to 1,400 cp by using our homemade torsion resonator apparatus in the 10 ~ 2,500 rad/s frequency range (continuous frequencies). Some results for typical viscoelastic polymers (two polyethylene oxide (PEO) aqueous solutions) are also given. Additionally, a comparison of the PEO results is made with the common rheometer technique. It is demonstrated that this improved strategy could enable the traditional torsional resonators, with one oscillating resonance mode, to work as the microrheological technique and the common rheometer technique in the continuous frequency range. 相似文献
105.
新型两亲性含糖嵌段聚合物的合成与自组装 总被引:1,自引:0,他引:1
以β-环糊精(β-CD)和2-乙基-2-噁唑啉(EtOz)为原料, 通过活性端基化学偶联法制备了乙酰麦芽七糖/聚(2-乙基-2-噁唑啉)两嵌段聚合物(AcMH-b-PEtOz), 借助核磁共振氢谱、红外光谱和凝胶渗透色谱等手段证实了产物的化学结构. 采用核磁共振氢谱、荧光光谱、透射电子显微镜、动态光散射及紫外-可见分光光度等方法探讨了产物在水溶液中的自组装行为. 结果表明, 所得嵌段聚合物直接溶于水后可通过自组装形成纳米球形“核-壳”结构胶束, 同时具有温度响应性. 所得聚合物的临界胶束浓度(cmc)为4~7 mg/L, 平均粒径(d)为83~115 nm, 临界相转变温度(LCST)为49~64 ℃, 并且均可通过PEtOz的链长进行调控. 相似文献
106.
Homogenous complexation of water-soluble polymers with chemically complementary structures in aqueous media has recently attracted great interest[1]. It is known that such macromolecules in solution can interact with each other, resulting in excluded volumes and ordered structures through the formation of soluble intermacromolecular complexes[2]. Therefore, such systems may possess unique properties that are different from those of individual components and there are many potential applications. 相似文献
107.
Hydrophobically modified water-soluble ion-containing cellulosic polymer possessing intra-or intermolecular modes of hydrophobic associations has been recently the object of our research[1-4]. Based on the preparation of the surface-active monomer, dimethyloctyl (2-methacryloxyethyl)ammonium bromide (DMOA), new cellulosic graft terpolymers (NCGT) have been synthesized by grafting acrylamide (AM) and DMOA onto carboxymethyl cellulose (CMC) using potassium persulfate and dimethylaminoethyl methacrylate as the initiating system, and characterized by FTIR, elementary analysis, titration and GPC. To obtain the optimum reaction conditions, the influence of the feed ratio and addition order of raw materials, the concentration of initiators, temperature and pH on the grafting have been investigated. 相似文献
108.
ZHOULi-Ming CHENTian-Lun 《理论物理通讯》2004,42(1):121-125
Based on the standard self-organizing map neural network model and an integrate-and-fire mechanism, we investigate the effect of the nonlinear interactive function on the self-organized criticality in our model. Based on the sewe also investigate the effect of the refractoryperiod on the self-organized criticality of the system. 相似文献
109.
LI Guang-Sheng YANG Li-Ming DAI Zheng-Yu LIU Xiang-An ZHANG Lan-Kuan WEN Shu-Xian WU Xiao-Guang YUAN Guan-Jun WENG Pei-Kun LI Sheng-Gang ZHU Sheng-Jiang YANG Chun-Xiang 《中国物理C(英文版)》2002,26(8):809-813
Lifetimes of the excited states in light rare-earth nucleus 130Ce have been measured using heavy ion reaction 116Sn(16O,2n)130Ce at beam energy of 73MeV through analyzing the Doppler-broadened line shapes. The reduced transition probabilities B(E2) are extracted from these measurements. The experimental results show that the previously reported anomalously high B(E2) value has not been observed in the present work. The transition quadrupole moment for the yrast band varies with spin and corresponds to a triaxial deformation with γ≈7°. 相似文献
110.
Plasma doping is the candidate for semiconductor doping. Accurate simulation of the doping technology is needed for the advanced integrated circuit manufacturing. In this paper, the plasma doping process simulation is performed by using the localized molecular dynamics method. Models that involve the statistics of the implanted compositions, angles and energies are developed. The effect of the model on simulation results is studied. The simulation results about the doping concentration profile are supported by experimental data. 相似文献