高可见光催化降解污染物和产氢活性的Z型N-掺杂K4Nb6O17/g-C3N4异质结

随着人口增长和全球工业化进程加快,人们饱受环境污染和能源短缺问题的困扰.半导体光催化技术作为一种高效、可持续、环境友好、有潜力的新技术,在环境净化和能源开发方面有着广阔的应用前景.到目前为止,人们已开发出多种半导体光催化剂,并广泛应用于污染物降解、氢气制备和二氧化碳还原等领域.其中,化合物K4Nb6O17具有典型的层状结构、合适的电子能带结构、结构易改性以及良好的电荷传输性能等特点,在光催化领域得到了广泛研究.然而,单纯K4Nb6O17仍存在光响应范围窄、光生载流子复合率高等问题,限制了K4Nb6O17的进一步应用.因此,需要对K4Nb6O17进行改性,拓宽其光吸收范围,提高其光生载流子分离效率,从而提高其光催化活性.本研究通过简单焙烧法制备Z型N-掺杂K4Nb6O17/g-C3N4(KCN)异质结光催化剂,其中石墨相氮化碳(g-C3N4)在复合材料中质量比约为50%.层状K4Nb6O17层板的电子结构通过N掺杂进行调控,拓宽其光响应范围,使其具有可见光响应;同时,形成的g-C3N4位于N-掺杂K4Nb6O17的外层以及内层空间,在这两种组分之间形成异质结,有利于提高光生载流子的分离效率.荧光光谱、时间分辨荧光光谱和光电化学测试表明,N掺杂和异质结的形成有利于增强光生电子-空穴对的传输和分离效率.通过在可见光照射下降解罗丹明B(RhB)和产氢来评估材料的光催化性能.相比g-C3N4(8.24μmol/h)和Me-K4Nb6O17(~1.30μmol/h),KCN复合材料光催化产氢效率(~16.91μmol/h)得到了极大提高,并显示出极好的光催化产氢稳定性能.对于光催化降解RhB体系,KCN复合材料也显示出较好的光催化活性和稳定性,并能很好地将RhB矿化.鉴于KCN复合材料具有较小的比表面积(9.9 m^2/g)且无孔结构,认为比表面积对光催化活性影响较小.因此,与单组分相比,KCN复合材料光催化产氢和RhB降解活性都得到了极大提高,活性的增强主要归功于N掺杂和异质结形成的协同效应,其中N掺杂可以拓宽光捕获能力,异质结形成可提高电荷载流子的分离效率.电子自旋共振(ESR)谱表明,在KCN降解RhB体系中,超氧自由基(·O2^?)、羟基自由基(·OH)和空穴(h^+)作为主要活性物质都参与了反应.结合实验结果可以推测KCN复合材料满足了Z型光催化体系,该体系具有高效的光生载流子分离效率和较高的氧化还原能力.     

Simultaneous studies of pressure effect on charge transport and photophysical properties in organic semiconductors: A theoretical investigation

High-mobility and strong luminescent materials are essential as an important component of organic photodiodes, having received extensive attention in the field of organic optoelectronics. Beyond the conventional chemical synthesis of new molecules, pressure technology, as a flexible and efficient method, can tune the electronic and optical properties reversibly. However, the mechanism in organic materials has not been systematically revealed. Here, we theoretically predicted the pressure-depended luminescence and charge transport properties of high-performance organic optoelectronic semiconductors, 2,6-diphenylanthracene (DPA), by first-principle and multi-scale theoretical calculation methods. The dispersion-corrected density functional theory (DFT-D) and hybrid quantum mechanics/molecular mechanics (QM/MM) method were used to get the electronic structures and vibration properties under pressure. Furthermore, the charge transport and luminescence properties were calculated with the quantum tunneling method and thermal vibration correlation function. We found that the pressure could significantly improve the charge transport performance of the DPA single crystal. When the applied pressure increased to 1.86 GPa, the hole mobility could be doubled. At the same time, due to the weak exciton coupling effect and the rigid flat structure, there is neither fluorescence quenching nor obvious emission enhancement phenomenon. The DPA single crystal possesses a slightly higher fluorescence quantum yield ～ 0.47 under pressure. Our work systematically explored the pressure-dependence photoelectric properties and explained the inside mechanism. Also, we proposed that the external pressure would be an effective way to improve the photoelectric performance of organic semiconductors.     

高稳定电化学扫描隧道显微镜研制

展示了一台自制的电化学扫描隧道显微镜. 这台电化学STM具有很高的稳定性,它在XY平面和Z方向的漂移速率分别为每分钟67和55.6 pm/min. 另外,特殊设计的扫描管部件有效地避免了在高湿度的环境中大漏电电流的产生. 详细描述了这台电化学STM的机械结构.通过在硫酸铜溶液中测量STM图像证明这套系统的优异性能,得到了大范围干净有序的Au(111)表面和高分辨的高聚石墨原子图像.     

氟比洛芬酯对子痫前期患者剖宫产术后静脉自控镇痛疗效观察

目的 观察氟比洛芬酯复合丁丙诺啡和单用丁丙诺啡对子痫前期患者剖宫产术后静脉自控镇痛（PCIA）的临床效果和 应用价值。方法 选择90例ASAⅠ～Ⅱ级在腰硬联合麻醉下行子痫前期剖宫产术患者,按随机数字表法分为A组（胎儿娩出后氟比洛芬酯+术后丁丙诺啡PCIA）、B 组（术后氟比洛芬酯+丁丙诺啡PCIA）和C 组（术后丁丙诺啡PCIA）,每组30例。观察并记录患者术后1、2、4、12、24h 视觉模拟评分（VAS）、Ramassay镇静评分,平均动脉压（MAP）、心率（HR）及术后恶心、呕吐、嗜睡、皮肤瘙痒等不良反应发生情况,分别于麻醉前、术后4、12 和24h抽取静脉血,检测血清肾上腺素、去甲肾上腺素、多巴胺、血浆儿茶酚胺和内皮素的水平。结果 A 组和B组患者术后各时点VAS 评分均明显低于C组（P＜0.05）,A 组和B 组各时点Ramsay 镇静评分均明显高于C组（P＜0.05）;A 组和B 组术后各时点MAP 和HR 均明显低于C 组（P＜0.05）;术后24h 内PCIA 按压次数A 组和B 组明显低于C组（P＜0.05）;A 组和B 组术后各时点血清肾上腺素、去甲肾上腺素、多巴胺和内皮素水平均明显低于C 组（均P＜0.05）;A 组术后4h 内皮素水平明显低于B 组（P＜0.05）;A 组和B 组头晕、嗜睡、恶心、呕吐发生率均低于C 组（均P＜0.05）。结论 氟比洛芬酯能有效抑制术后应激,镇痛效果好且不良反应少,在胎儿娩出后应用氟比洛芬酯并结合术后丁丙诺啡进行PCIA更适合用于子痫前期剖宫产术后患者术后镇痛。     

New analytical method for the study of the metabolism of gentiopicroside in rats after oral administration by LC–TOF‐MS following picolinoyl derivatization

The metabolism of gentiopicroside (GPS) in vivo was studied for the first time by LC–MS following picolinoyl derivatization. Incubation of erythrocentaurin, one of the main in vitro metabolites of GPS by intestinal bacteria, with liver microsome indicated that GPS might be metabolized to a final metabolite 3,4‐dihydro‐5‐(hydroxymethyl)isochroman‐1‐one (HMIO) in vivo. After hydrolysis with sulfatase, HMIO was successfully detected in rat plasma after oral administration of GPS by LC–MS following picolinoyl derivatization. 4‐Methoxyphenyl methanol was used as an internal standard to quantify HMIO in rat plasma. A metabolic pathway of GPS in rats is proposed. The monoterpene compound GPS was found to be metabolized to dihydroisocoumarin, which may be responsible for the pharmacological effect of GPS.     

Preparation and characterization of Ti0.7Sn0.3O2 as catalyst support for oxygen reduction reaction

Sn-doped TiO_2 nanoparticles with high surface area of 125.7 m~2·g~(-1) are synthesized via a simple one-step hydrothermai method and explored as the cathode catalyst support for proton exchange membrane fuel cells.The synthesized support materials are studied by X-ray diffraction analysis,energy dispersive X-ray spectroscopy and transmission electron microscopy.It is found that the conductivity has been greatly improved by the addition of 30 mol%Sn and Pt nanoparticles are well dispersed on Ti_(0.7)Sn_(0.3)O_2 support with an average size of 2.44 run.Electrochemical studies show that the Ti_(0.7)Sn_(0.3)O_2 nanoparticles have excellent electrochemical stability under a high potential compared to Vulcan XC-72.The as-synthesized Pt/Ti_(0.7)Sn_(0.3)O_2 exhibits high and stable electrocatalytic activity for the oxygen reduction reaction.The Pt/Ti_(0.7)Sn_(0.3)O_2 catalyst reserves most of its electrochemically active surface area(ECA),and its half wave potential difference is 11 mV,which is lower than that of Pt/XC-72(36 mV) under 10 h potential hold at 1.4 V vs.NHE.In addition,the ECA degradation of Pt/Ti_(0.7)Sn_(0.3)O_2is 1.9 times lower than commercial Pt/XC-72 under 500 potential cycles between 0.6 V and 1.2 V vs.NHE.Therefore,the as synthesized Pt/Ti_(0.7)Sn_(0.3)O_2 can be considered as a promising alternative cathode,catalyst for proton exchange membrane fuel cells.     

宽幅钢箱梁环焊缝焊接顺序优化研究

基于热弹塑性有限元法,采用ANSYS软件建立了网格疏密过渡的单箱五室钢箱梁壳单元模型;结合高效的分段移动热源,实现了对大型复杂长焊缝结构焊接全过程的数值模拟,并定性对比了宽幅钢箱梁在不同的环焊缝焊接顺序下顶板和底板的变形情况.分析结果表明:腹板焊缝的焊接顺序对竖向最大变形值(绝对值)的影响不大,其值主要取决于顶板和底板...     

Rational design of iridium–porphyrin conjugates for novel synergistic photodynamic and photothermal therapy anticancer agents

Near-infrared (NIR) emitters are important probes for biomedical applications. Nanoparticles (NPs) incorporating mono- and tetranuclear iridium(iii) complexes attached to a porphyrin core have been synthesized. They possess deep-red absorbance, long-wavelength excitation (635 nm) and NIR emission (720 nm). TD-DFT calculations demonstrate that the iridium–porphyrin conjugates herein combine the respective advantages of small organic molecules and transition metal complexes as photosensitizers (PSs): (i) the conjugates retain the long-wavelength excitation and NIR emission of porphyrin itself; (ii) the conjugates possess highly effective intersystem crossing (ISC) to obtain a considerably more long-lived triplet photoexcited state. These photoexcited states do not have the usual radiative behavior of phosphorescent Ir(iii) complexes, and they play a very important role in promoting the singlet oxygen (¹O₂) and heat generation required for photodynamic therapy (PDT) and photothermal therapy (PTT). The tetranuclear 4-Ir NPs exhibit high ¹O₂ generation ability, outstanding photothermal conversion efficiency (49.5%), good biocompatibility, low half-maximal inhibitory concentration (IC₅₀) (0.057 μM), excellent photothermal imaging and synergistic PDT and PTT under 635 nm laser irradiation. To our knowledge this is the first example of iridium–porphyrin conjugates as PSs for photothermal imaging-guided synergistic PDT and PTT treatment in vivo.

Iridium–porphyrin conjugates assembled in nanoparticles are photosensitizers that exhibit excellent photothermal imaging and synergistic PDT and PTT in vivo.     

50,52,53,54Cr光核反应数据评价

通过分析光子诱发52,50Cr核反应的各类实验数据,澄清52Cr光子吸收截面评价数据与中子、质子出射截面测量值间的分歧,给出了52Cr中子出射截面实验数据的修正;选取EGLO模型光子强度函数,结合准氘模型,给出光子吸收截面。在此基础上,采用最新研制的光子与中重核反应计算程序MEND-G,通过优化理论模型参数,包括剩余核的能级密度和对能修正参数,给出光子能量在200 MeV范围内的n、p、${{\rm{\alpha }}}$等粒子出射核反应的截面,52,50Cr的计算结果在30 MeV以下能区很好地符合了现有实验数据,并按国际标准ENDF/B-6库格式给出了50,52,53,54Cr的全套数据文档,便于核工程用户使用。