Solution of general dynamic equation for nanoparticles in turbulent flow considering fluctuating coagulation

A new averaged general dynamic equation (GDE) for nanoparticles in the turbulent flow is derived by considering the combined effect of convection, Brownian diffusion, turbulent diffusion, turbulent coagulation, and fluctuating coagulation. The equation is solved with the Taylor-series expansion moment method in a turbulent pipe flow. The experiments are performed. The numerical results of particle size distribution correlate well with the experimental data. The results show that, for a turbulent nanoparticulate flow, a fluctuating coagulation term should be included in the averaged particle GDE. The larger the Schmidt number is and the lower the Reynolds number is, the smaller the value of ratio of particle diameter at the outlet to that at the inlet is. At the outlet, the particle number concentration increases from the near-wall region to the near-center region. The larger the Schmidt number is and the higher the Reynolds number is, the larger the difference in particle number concentration between the near-wall region and near-center region is. Particle polydispersity increases from the near-center region to the near-wall region. The particles with a smaller Schmidt number and the flow with a higher Reynolds number show a higher polydispersity. The degree of particle polydispersity is higher considering fluctuating coagulation than that without considering fluctuating coagulation.     

Targeted therapy of SMMC-7721 liver cancer in vitro and in vivo with carbon nanotubes based drug delivery system

A new type of drug delivery system (DDS) involved chitosan (CHI) modified single walled carbon nanotubes (SWNTs) for controllable loading/release of anti-cancer doxorubicin (DOX) was constructed. CHI was non-covalently wrapped around SWNTs, imparting water-solubility and biocompatibility to the nanotubes. Folic acid (FA) was also bounded to the outer CHI layer to realize selective killing of tumor cells. The targeting DDS could effectively kill the HCC SMMC-7721 cell lines and depress the growth of liver cancer in nude mice, showing superior pharmaceutical efficiency to free DOX. The results of the blood routine and serum biochemical parameters, combined with the histological examinations of vital organs, demonstrating that the targeting DDS had negligible in vivo toxicity. Thus, this DDS is promising for high treatment efficacy and low side effects for future cancer therapy.     

Applications of silica-based nanoparticles for multimodal bioimaging

Multimodal imaging, as an important approach to circumvent the limitations of single imaging modality, has attracted extensive attention in recent years. With the rapid development of nanotechnology and the ongoing efforts to improve their targeting capability and endow multiple imaging ability, nanoprobes are expected to play crucial roles in multimodal imaging through integrating different imaging moieties or molecules into a single nanoparticle, where silica has been used intensively as a carrier or a medium for the construction of the nanoprobes due to its preferable characteristics including good biocompatibility, long blood circulation time, and ease of modification. Based on the types of the silica used for the fabrication of nanoprobes, solid silica-based and mesoporous silica-based nanoparticles were developed for multimodal imaging. Herein, the newly developed silica-based nanoparticles as multimodal imaging agents for disease diagnosis and therapy in the last 5 years were summarized, along with their fabrication process, specific applications, and especially the role of the silica.     

超细均分散稀土化合物胶体粒子制备

利用尿素分解法制得轻、中、重稀土化合物的超细均分散胶体粒子,详细探讨了浓度、pH值、陈化温度、陈化时间及共存阴离子等因素对制备过程的影响,获得了各种粒子的最佳制备条件.     

驻波的能量分析与MATLAB模拟

分析了驻波能量、能量密度、能流密度在传播过程中的转换规律.用Matlab程序实现了驻波波形、能量密度、能流密度的计算机模拟,形象地展现了驻波传播过程中的能量变化,计算机模拟结果与理论分析所得结果一致.最后得到了在振动过程中驻波能量不断地从波节到波腹间相互转移,而从整体看驻波不传播任何能量的结论.     

Pomegranate rind-derived activated carbon as electrode material for high-performance supercapacitors

In this paper, activated carbon materials were synthesized from pomegranate rind through carbonization and alkaline activation processes. The effects of pyrolytic temperature on the textual properties and electrochemical performance were investigated. The surface area of the activated carbon can reach at least 2200 m² g^?1 at different pyrolytic temperatures. It was found that, at the range of 600–900 °C, decreasing the carbonization temperature leads to the increase of t-plot micropore area, t-plot micropore volume, and capacitance. Further decreasing the carbonization temperature to 500 °C also leads to the increase of t-plot micropore area and t-plot micropore volume, but the capacitance is slightly poorer. The activated carbon carbonized at 600 °C and activated at 800 °C possesses very high specific area (2931 m² g^?1) and exhibits very high capacitance (～268 F g^?1 at 0.1 A g^?1 and ～242 F g^?1 at 1 A g^?1). There is no capacitance fading after 2000th cycle.     

西龙池抽水蓄能电站下水库BW2危岩稳定性分析

BW2危岩位于山西西龙池抽水蓄能电站下水库进/出水口和地面开关站及副厂房附近,其下部基座由较软的砂质页岩夹竹叶状灰岩构成,上部为坚硬的厚层泥质条带状灰岩,而且由于受到F118断层割切,已形成一座柱状的分离体。这种上硬下软的结构是BW2危岩岩体产生卸荷松动变形的根本原因。如果BW2危岩体发生破坏,将对水库安全产生巨大的影响。通过系统分析BW2危岩体的工程地质条件后,提出了危岩体可能的破坏模式,然后利用刚体极限平衡和快速拉格朗日(FLAC^3D)方法对危岩体在4种不同工况条件下的稳定性进行评价和预测,并提出危岩防治措施。     

NaYF4:Yb3+/Er3+单颗粒微米棒偏振上转换发光及其取向示踪

稀土掺杂微/纳材料的偏振上转换发光在单颗粒示踪和生物医学等领域具有广泛的应用前景.稀土离子的偏振上转换发光主要取决于其局域态的电子结构和激发态动力学.利用单颗粒偏振上转换光学测试平台对β-NaYF₄:Yb³⁺/Er³⁺微米棒的偏振上转换发光进行了系统研究.随发射偏振角的变化,单个微米棒的上转换发光强度发生周期性改变,且来自Er³⁺同一光谱支项的不同晶体场子能级跃迁的偏振方向不同.与光谱支项整体的上转换发光相比,其晶体场子能级上转换发光表现出更大的发射偏振度.利用Er³⁺高度偏振的晶体场跃迁谱线,实现了对单个微米棒空间取向的动态分析,揭示了NaYF₄:Yb³⁺/Er³⁺微米棒作为偏振各向异性的上转换荧光探针在单颗粒取向示踪方面的潜在应用.     

低成本富勒烯衍生物电子传输层在钙钛矿太阳能电池的应用

Organic-inorganic hybrid perovskite solar cells (PSCs) have attracted significant attention owing to their high absorption coefficient and ambipolar charge transport properties. With only several years of development, the power conversion efficiency (PCE) has increased from 3.8% to 22.7%. In general, PSCs have two types of structural architecture: mesoporous and planar. The latter possesses higher potential for commercialization due to its simpler structure and fabrication process, especially the inverted planar structure, which possesses negligible hysteresis. In an inverted PSC, the electron transport materials (ETM) are deposited on a perovskite film. Only a few ETMs can be used for inverted PSCs as the perovskite film is easily damaged by the solvent used to dissolve the ETM. Furthermore, the energy levels of the ETM should be well aligned with that of the perovskites. Normally it is difficult to use inorganic ETMs as they require high temperatures for the annealing process to improve the electron conductivity; the perovskite film cannot sustain these high temperatures. To date, the fullerene derivative, [6, 6]-phenyl-C61-butyric acid methyl ester (PCBM), is the most commonly used organic ETM for high efficiency inverted planar PSCs. However, the high manufacturing cost due to its complex synthesis retards the industrialization of the PSCs. Here, we introduce a fullerene pyrrolidine derivative, N-methyl-2-pentyl-[60]fullerene pyrrolidine (NMPFP), synthesized via the Prato reaction of C₆₀ directly with cheap hexanal and sarcosine. Then the NMPFP electron transport layer (ETL) was prepared by a simple solution process. The properties of the resulting NMPFP ETLs were characterized using UV-Vis absorption spectroscopy, cyclic voltammetry measurements, atomic force microscopy, and conductivity test. From the results of the UV-Vis absorption spectroscopy and cyclic voltammetry measurements, the LUMO level of NMPFP ETL was calculated to be 0.2 eV higher than that of the PCBM ETL. This contributes to a higher open-circuit photovoltage. In addition, the NMPFP film presented higher conductivity than the PCBM film. Thus, the photo-generated charge carriers in the perovskite films should be transported more efficiently to the NMPFP electron transport layer (ETL) than to the PCBM ETL. This was confirmed by the results of the steady-state photoluminescence spectroscopy. Finally, the NMPFP as an alternative low-cost ETL was employed in an inverted planar PSC to evaluate the device performance. The device made with the NMPFP ETL yielded an efficiency of 13.83% with negligible hysteresis, which is comparable to the PCBM counterpart devices. Moreover, since stability is another important parameter retarding the commercialization of PSCs, the stability of the PCBM and NMPFP base PSCs were investigated and compared. It was found that the NMPFP devices possessed significantly improved stability due to the higher hydrophobicity of the NMPFP. In conclusion, this research demonstrates that NMPFP is a promising ETL to replace PCBM for the industrialization of cheap, efficient and stable inverted planar PSCs.