羟基磷灰石负载锰催化溴苯的Suzuki反应

以羟基磷灰石(HAP)负载Mn作为催化剂(MnHAP)催化溴苯与苯硼酸的Suzuki交叉偶联反应.以氟离子交换羟基磷灰石的羟基(MnFAP)后,催化剂的活性显著提高,在优化的反应条件下能得到约70%的产率.进一步考察了溶剂和不同取代基的影响.结果表明,MnFAP作用下溶剂极性对反应有很大影响,当溶剂DMF/H2O比例为1/3时产率最高.对于不同取代基取代的溴代芳烃或苯硼酸,可以得到中等产率(18%~46%)的偶联产物.     

砖砌体双参数单轴受压弹塑性损伤力学模型

参考弹塑性损伤模型理论和相关试验数据,建立了砖砌体单轴单调受压和重复受压两种弹塑性损伤本构模型.在模型中采用抗压强度和峰值压应变双参数来调整形变曲线,从而实现了砖砌体单轴受压本构模型的精细化建立.模型不但与既有弹塑性模型相符,而且还符合受压延性与强度呈反向变化的试验结论.重复受压加-卸载路径建立在卸载线性假定的基础上,参考两组试验数据,得出了双线性抗压刚度劣化函数,并通过强度线性插值来调整劣化速率,从而建立了随强度改变的受压加-卸载损伤本构模型.     

新技术变革时代“人”的变迁与社会法回应

近代社会,个人被抽象为无差别、理性且平等的主体,资本家以“契约自治”之名对劳动者实行残酷的剥削,唤起了人们对抽象人之理论预设的反思。由此,扶助弱者、带有倾斜保护意蕴的社会立法兴起。互联网技术催生的平台经济在拉动就业的同时,也消解着传统劳动关系。自动化技术的发展使得低技能劳动者、从事常规工作的中间阶层面临被就业市场淘汰的风险。公私法融合属性的社会法制度,在应对灵活就业和技术失业问题上显得乏力,社会法应向更纯粹的私法和更广泛的公法靠拢,分类协同规范相关社会关系：充分尊重当事人双方的意思自治,淡化劳动合同中不必要的管制色彩;从人权保护视角重新定位劳动基准法,将受教育权的国家义务具体化,建立以全民基本收入为核心的社会保障体系。     

细胞膜修饰的纳米载体与肿瘤免疫治疗

纳米载体由于其纳米尺度带来的独特生物功能性,可通过特定设计在生物体内靶向递送各类抗肿瘤药物,具有广泛而重要的应用前景.自肿瘤免疫疗法问世之后,各类纳米载体与肿瘤免疫治疗相结合,逐渐成为提升肿瘤免疫治疗效果的重要手段之一.其中,细胞膜修饰的纳米载体作为一类新型仿生药物载体平台,可使纳米载体获得天然细胞膜的伪装修饰,将细胞...     

Tailoring electron transfer with Ce integration in ultrathin Co(OH)2 nanosheets by fast microwave for oxygen evolution reaction

The intrinsic activity of Co(OH)2 for oxygen evolution reaction (OER) may be elaborately improved through the suitable valence adjustment.Ce modification at ele...     

激光系统中半导体激光器温度稳定系统研究与设计

激光器系统中半导体激光器的功率输出稳定度和工作温度有很大的关系,为了使大功率半导体激光器输出功率稳定,需要对激光器实现高精度、快速温度控制。针对现有的激光系统中激光器温度控制系统存在控制精度不够高、控制速度慢等问题,设计了一种温度稳定系统,采用PT-100热电偶测量激光器温度,并使用最小二乘法对温度数据进行拟合,使得温度测量精度达到0.01 ℃;使用改进粒子群算法优化(PSO)的PID控制器实现温度控制。仿真实验和实际测试表明,所设计的温度稳定系统能够很好地控制激光器温度,达到目标温度所需的调节时间小于11 s,达到稳态后温度波动在±0.02 ℃内。与传统的温度控制方式相比,所设计的系统能够实现参数自整定并自动调节温度,对大功率激光系统中激光器温度具有良好稳定效果。     

Tailoring the AIE Chromogen 2-(2-Hydroxyphenyl)benzothiazole for Use in Enzyme-Triggered Molecular Brachytherapy

A targeted strategy for treating cancer is antibody-directed enzyme prodrug therapy, where the enzyme attached to the antibody causes conversion of an inactive small-molecule prodrug into an active drug. A limitation may be the diffusion of the active drug away from the antibody target site. A related strategy with radiotherapeutics entails enzymatically promoted conversion of a soluble to insoluble radiotherapeutic agent, thereby immobilizing the latter at the target site. Such a molecular brachytherapy has been scarcely investigated. In distinct research, the advent of molecular designs for aggregation-induced emission (AIE) suggests translational use in molecular brachytherapy. Here, several 2-(2-hydroxyphenyl)benzothiazole substrates that readily aggregate in aqueous solution (and afford AIE) were elaborated in this regard. In particular, (1) the 2-(2-hydroxyphenyl) unit was derivatized to bear a pegylated phosphodiester that imparts water solubility yet undergoes enzymatic cleavage, and (2) a p-phenol unit was attached to the benzo moiety to provide a reactive site for final-step iodination (here examined with natural abundance iodide). The pegylated phosphodiester-iodinated benzothiazole undergoes conversion from aqueous-soluble to aqueous-insoluble upon treatment with a phosphatase or phosphodiesterase. The aggregation is essential to molecular brachytherapy, whereas the induced emission of AIE is not essential but provides a convenient basis for research development. Altogether, 21 compounds were synthesized (18 new, 3 known via new routes). Taken together, blending biomedical strategies of enzyme prodrug therapy with materials chemistry concerning substances that undergo AIE may comprise a step forward on the long road toward molecular brachytherapy.     

Gelatin-Derived 1D Carbon Nanofiber Architecture with Simultaneous Decoration of Single Fe−Nx Sites and Fe/Fe3C Nanoparticles for Efficient Oxygen Reduction

Exploring high-performance non-precious-metal electrocatalysts for the oxygen reduction reaction (ORR) is critical. Herein, a scalable and cost-effective strategy is reported for the construction of one-dimensional carbon nanofiber architectures with simultaneous decoration of single Fe−N_x sites and highly dispersed Fe/Fe₃C nanoparticles for efficient ORR, through the Fe^III-complex-assisted electrospinning of gelatin nanofibers with subsequent pre-oxidation and carbonization. Results show that the presence of a Fe^III complex enables the 1D gelatin nanofibers to be well retained during the pre-oxidation process. Owing to the distinct 1D nanofiber structure and the synergistic effect of Fe/Fe₃C and Fe−N_x sites, the resulting electrocatalyst is highly active for ORR with a half-wave potential of 0.885 V (outperforming commercial Pt/C) and a superior electrochemical stability in alkaline electrolytes. Similarly, it also shows a high power density (144.7 mW cm⁻²) and a superior stability in Zn-air batteries. This work opens a path for the design and synthesis of 1D carbon electrocatalyst for efficient ORR catalysis.     

One-pot synthesis of NiPt core–shell nanoparticles toward efficient oxygen reduction reaction

Journal of Solid State Electrochemistry - Creating bimetallic Pt-based nanocrystals with core–shell structures has widely been recognized as the most effective way for improving their...