The intragastrointestinal fate of paclitaxel-loaded micelles: Implications on oral drug delivery

The goal of the present study is to elucidate the intragastrointestinal fate of micellar delivery systems by monitoring fluorescently labeled different micelles and the model drug paclitaxel (PTX). Both in vitro and ex vivo leakage studies showed fast PTX release in fluids while micelles remained intact, except in fed-state simulated intestinal fluid and fasted-state pig intestinal fluid, thus referring to the intact absorption of micelles and PTX leakage in the gastrointestinal tract with d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) micelles showing higher stability than other micelles. All groups of micelles were absorbed intact in Caco-2 and Caco-2/HT29-MTX cell models and the absorption of TPGS micelles was found to be higher than other micelles. The transport of the micelles across Caco-2/Raji (1.6%–3.5%), Caco-2 (0.8%–1%), and Caco-2/HT29-MTX (0.58%–1%) cell monolayers further verified the absorption of micelles and their subsequent transport; however, more TPGS micelles transported across cell monolayers than other groups. Moreover, the histological examination also confirmed that micelles entered the enterocytes and were transported to basolateral tissues and TPGS showed the stronger ability of penetration than other groups. Thus, these results are succinctly presenting the absorption of intact micelles in GIT confirmed by imaging evidence with prior leakage of the drug, uptake by enterocytes and the transport of micelles that survive the digestion by enterocytes and mainly by microfold cells in material nature dependent way with TPGS showing better results than other groups. In conclusion, these results identify the mechanism by which the gastrointestinal tract processes micelles and point to the likely use of this approach in the design of micelles-based therapies.     

Ruthenium(II)-catalyzed para-selective CH difluoroalkylation of aromatic aldehydes and ketones using transient directing groups

A Ru(II)-catalyzed para-difluoroalkylation of aromatic aldehydes and ketones with a transient directing group has been developed. It utilizes less expensive ruthenium catalysts and allows facile access to challenging difluoroalkylated aldehydes. The mechanism studies suggest that the distinct coordination mode of ruthenium complex with imine moieties is responsible for para-selectivity.     

Study on LiFe<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Sm<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>PO<Subscript>4</Subscript>/C used as cathode materials for lithium-ion batteries with low Sm component

LiFe_1???x Sm _x PO₄/C cathode materials were synthesized though a facile hydrothermal method. Compared with high-temperature solid-phase sintering, the method can allow for the fabrication of low Sm content (2 %), a scarce and expensive rare earth element, while the presence of an optimized carbon coating with large amount of sp²-type carbon sharply increases the material’s electrochemical performance. The high-rate dischargeability at 5 C, as well as the exchange current density, can be increased by 21 and 86 %, respectively, which were attributed to the fine size and the large cell parameter a/c as much. It should be pointed out that the a/c value will be increased for the LiFePO₄ Sm-doped papered by both of the two methods, while the mechanism is different: The value c is increased for the front and the value a is decreased for the latter, respectively.     

高超声速平板边界层流动显示的试验研究

本文在高超声速脉冲式风洞内对基于纳米示踪的平面激光散射技术(nano-based planar laser scattering, NPLS)的应用进行了探索, 并在此基础上对平板边界层流动结构的精细测量进行了研究. 试验来流Ma=7.3, 总压4.8 MPa, 总温680 K. 通过时序的分析和调试, 对各分系统实现了高精度的同步控制; 定量的粒子注入及混合, 实现了粒子的均匀撒播, 对主流获得了均匀的显示效果; 对于边界层流动, 获得了精细的瞬态流动结构图像, 显示了层流到湍流的转捩过程, 并分析了其时空演化特性.     

基于数值原子轨道基组的第一性原理计算软件ABACUS

随着超级计算机硬件和数值算法迅速发展, 使得目前利用密度泛函理论研究上千个原子体系的电子能带和结构等性质变得可行. 数值原子轨道基组由于其基组较小和局域等特性, 可以很好地与电子结构计算中的线性标度算法等的新算法结合, 用来研究较大尺寸的物理体系. 本文详细介绍了一款中国科学技术大学量子信息重点 实验室自主开发的基于数值原子轨道基组的第一性原理计算软件 Atomic-orbital Based Ab-initio Computation at UStc. 大量的测试结果表明: 该软件具有很好的准确性和较高的并行效率, 可以用于包含1000个原子左右的系统的电子结构和原子结构的研究以及分子动力学模拟计算.     

N2H4在NiFe(111)合金表面吸附稳定性和电子结构的第一性原理研究

采用基于色散校正的密度泛函理论进行了第一性原理研究, 详细分析了肼(N₂H₄)在Ni₈Fe₈/Ni(111)合金表面稳定吸附构型的吸附稳定性和电子结构及成键性质. 通过比较发现, 肼分子以桥接方式吸附在表面的两个Fe原子上是最稳定的吸附构型, 其吸附能为-1.578 eV/N₂H₄. 同时发现, 肼分子在这一表面上吸附稳定性的趋势为: 桥位比顶位吸附更有利, 且在Fe原子上比在Ni原子上的吸附作用更强. 进一步分析了不同吸附位点上稳定吸附构型的电子结构、电荷密度转移以及电子局域化情况. 结果发现: 相同吸附位点的电子态密度图基本一致, 并且N原子的p轨道和与之相互作用的表面原子的d轨道之间存在态密度上的重叠; 吸附后电荷密度则主要从肼分子转移到表面原子之上; 在电子局域化函数切面图中也发现吸附后电子被局域到肼分子的N原子和相邻的表面原子之间. 这些电子结构的表征都充分说明肼分子与表面原子之间通过电荷转移形成了强烈的配位共价作用.