羟基磷灰石/胶原矿化机理的研究进展

仿生合成的羟基磷灰石(HAp)/胶原复合材料的结构和成分与天然骨相似,具有很好的生物相容性、生物活性和生物可降解性,有望成为新一代的骨替代材料。羟基磷灰石/胶原矿化过程其实质是晶体在自组装的胶原纤维上形成的过程,但这一过程在体内是如何进行的至今仍然不清楚。对胶原矿化机理的研究能为制备具有更优越结构和功能的新型骨替代材料提供理论参考。本文概述了羟基磷灰石/胶原矿化机理的研究进展。     

Novel multifunctional theranostic nanoagents based on Ho3+ for CT/MRI dual-modality imaging-guided photothermal therapy

Because of the intrinsic defects of traditional treatment of cancer,it is quite needed to construct novel theranostic nanoagents that can not only improve the accuracy of imaging diagnosis but also achieve highly efficient therapy of cancer.Herein,we fabricated polydopamine-functionalized ammonium holmium fluoride nanocomposites(AHF@PDA)for dual-modality bioimaging(magnetic resonance imaging(MRI)and computed tomography(CT))owing to the high X-ray attenuation feature and magnetic property of Ho³⁺.Moreover,PDA shell endows AHF@PDA with excellent photothermal conversion performances and robust biocompatibility,leading to good treatment effect in vitro and in vivo.All above positive results certify that AHF@PDA have good potential as theranostic agents for clinical application in the future.     

利用Heck反应合成咖啡酸苯乙酯

以4-溴儿茶酚和丙烯酸苯乙酯为原料,经过邻二酚羟基的保护、Heck偶联和脱保护3步反应合成了咖啡酸苯乙酯.其中,以乙酰基保护的4-溴儿茶酚在优化的Heck反应条件下,可获得40%收率的咖啡酸苯乙酯.确定的最佳Heck反应条件为:混合溶剂甲苯/二甲基甲酰胺的体积比为4∶1,醋酸钯(0.05 mmol),三苯基膦(0.15 mmol),三乙胺(2 mmol),反应温度90℃,反应时间24 h.该方法具有通用性好、原料易得和操作相对简单的优点.     

An enantiospecific synthesis of (+)-demethoxyerythratidinone from (S)-malic acid: key observations concerning the diastereocontrol in malic acid-derived N-acyliminium ion cyclisations

The stereochemical outcome of N-acyliminium ion mediated cyclisations of malic acid derived lactams depend upon the nature of the protecting group on the lactam secondary alcohol, and also on the nature of the substituent at the reacting electrophilic centre. The origins of an unusual syn-selective cyclisation of a TIPS protected lactam are discussed, and the cyclisation is employed as the key step in an asymmetric synthesis of 3-demethoxyerythratidinone (4).     

不同位置Mg掺杂ZnO电荷转移和光学性质的第一性原理研究

基于密度泛函理论计算了本征氧化锌、6.25％Mg以及同位、邻位、间位12.5％Mg原子掺杂氧化锌晶体的几何结构、原子轨道电子布居、静电势和电子结构特征;探究了Mg原子掺杂对氧化锌能带结构、态密度以及对应的光学性质和电学性质的影响.结果表明Mg掺杂会导致氧化锌晶体的晶格体积变大,载流子迁移率降低和吸收边蓝移;邻位双原子掺...     

我最得意的一堂杠杆浮力综合习题实验课

众所周知,实验是物理的教学之本,习题课的教学也应加强实验.教师精选例题,并尽量创设条件给例题配上实验,在观察对比中寻求解题的思路与方法,把原来学生感到枯燥的习题课上得生动活泼,以达到提高教学效果之目的.     

二氧化钛选择性光催化降解有机污染物研究进展

半导体二氧化钛已被广泛应用于有机污染物的光催化降解,但其主要是通过光与二氧化钛作用产生的羟基自由基与有机污染物发生自由基氧化反应,这种自由基反应在降解污染物时没有选择性,当几种有机污染物共存时,它优先催化降解吸附在其表面的高浓度污染物,而低浓度的有机污染物因吸附量少而达不到有效降解。因此,研究开发具有高选择性的能降解低浓度高毒性有机污染物的二氧化钛材料是环境科学领域亟待解决的热点之一。本文综述了近十年来二氧化钛选择性光催化降解有机污染物的研究动态和主要成果,并对未来发展趋势进行展望。     

Atomic Spectrum in Ramsey Separated Oscillating Fields with Three Interaction Regions

Comparing with the situation of Ramsey separated oscillating fields used in Cesium atomic beam frequency standard, the transition probability spectrum of two-level atoms in the Ramsey separated oscillating fields with three interaction regions has been derived under the condition of near resonance. The new characteristic of atomic spectrum with excessive microwave power was analyzed in detail. Meantime, the predicted new characteristic of atomic spectrum was confirmed by numerical method in this paper.     

大北天然气防蜡剂的合成及防蜡机理研究

为防止大北天然气集输过程中管道结蜡,针对大北天然气处理厂天然气和石蜡的性质,以丙烯酸高碳醇酯（丙烯酸十二酯、丙烯酸十八酯）、顺丁烯二酸酐（MA）和4-烯丙基苯甲醚（AA）为原料合成了两种防蜡剂EMAAA-12和EMAAA-18;通过全温域模拟相图、析蜡曲线和FBRM粒径分布分析了防蜡剂对天然气物性的影响。结果表明：添加防蜡剂后的析蜡曲线向低温区偏移,防蜡剂可显著降低天然气的析蜡点温度。随着温度降低,大弦长粒子的数量整体增加,而粒径分布无明显突变。防蜡剂自身超支化结构有益于与石蜡相互作用形成共晶,抑制石蜡晶体的长大和自身聚结,从而达到防蜡的效果。     

Velocity Distribution of Effective Atoms in a Small Optically Pumped Cesium Beam Frequency Standard

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