具有高效激子解离和明确反应位点的Tröger碱基三维多孔芳基有机骨架及其光催化近单一选择性CO_(2)转化

植物光合作用是吸收光能,把CO_(2)和水转化成富能有机物,同时释放氧气的过程.受此启发,利用太阳光将CO_(2)转化为碳氢燃料的人工碳中和技术引起了广泛关注.人工光合作用能否成功实施取决于光催化剂的设计制备.无机半导体已被广泛研究用于CO_(2)光还原反应(CO_(2)PRR),但其存在金属氧化物的带隙较宽且难以调节、导致光吸收较差和金属硫化物的光腐蚀问题严重等明显的缺点.此外,高载流子复合率和低比表面积会影响光催化效率,从而限制光子利用.因此,基于有机聚合物的无金属催化剂因其突出的可设计调控性而被提出,其中,具有超高比表面积的材料—多孔芳香骨架(PAFs)聚合物是研究热点之一,但是传统PAFs材料多为二维平面结构,用于光催化的无金属三维PAFs报道较少.此外,具有孤对电子的杂原子(N,B,F)修饰的材料可以与CO_(2)分子产生特定的偶极-四极相互作用,提高材料对CO_(2)的吸附和活化能力,是提升有机聚合物光催化剂性能的有效策略.本文采用Sonogashira-Hagihara偶联将具有不同共轭程度的芳香炔烃(2,2’,7,7‘-四乙炔基-9,9’-螺二芴,SPF-T;四(4-乙炔基苯基)甲烷,TEPM-T;1,1,2,2-四(4-乙炔基苯基)乙烯,TEPE-T)与含有N杂原子的Tröger碱聚合制备了具有三维结构的多孔芳香骨架聚合物X-TB-PAFs(X=TEPE,TEPM,SPF).通过X-射线衍射、红外光谱、13C核磁共振(NMR)以及1H NMR等表征手段验证了目标聚合物的成功合成.通过紫外-可见光谱和Mott-Schottky曲线测试研究了聚合物具体的能带结构,发现三种PAFs聚合物材料在热力学上同时满足光催化CO_(2)-CO的还原反应条件(Eθ=-0.51 Vvs.NHE,pH=7)和光催化H2O-O_(2)的氧化条件(Eθ=0.82 V vs.NHE,pH=7).V形骨架结构的Tröger碱(TB)单元和芳炔的结合赋予了聚合物刚性稳定的孔隙率以及较高的比表面积,材料中的多孔结构可以使其暴露更多的活性位点,三维框架结构为反应物接近活性位点提供了丰富的开放式空腔,这些都有利于材料对CO_(2)的捕获,增强催化剂对CO_(2)的吸附/活化能力.此外,炔基充当连接通道还可以增强体系的载流子迁移率,提升材料的光催化性能.密度泛函理论计算和光电性能测试结果表明,TB官能团引入带来的分子内极化和电子陷阱位点的优势,其与三维共轭网络结构一起协同调节了光生载流子的分离和反应位点分布.三种三维PAFs中,基于全共轭结构TEPE-T的TEPE-TB-PAF表现出最高效的光生载流子传输与分离效率,在没有助催化剂和牺牲剂的情况下表现出较好的光催化CO产率(194.50μmolg^(-1)h^(-1))和近乎单一的选择性(99.74%).全共轭TEPE-T的引入和分子内极化的存在可以促进框架内载流子的分离和迁移.材料中的电偶极矩(从负电荷到正电荷)指向TB中含有叔氮官能团的桥接位点,使其成为明确的催化反应位点.光电流和阻抗测试结果表明,TEPE-TB-PAF具有更好的电子-空穴分离能力和更小的电荷迁移位阻.三维框架构建产生的多重散射截面可以促进材料中的光子吸收,从而提高其光催化性能.理论计算和原位漫反射傅立叶变换红外光谱结果表明,材料中CO解吸的低能垒和*CHO形成的高能垒是TEPE-TB-PAF高CO产率和选择性的根本机制.综上,本文为多功能高效有机聚合物光催化剂的合成提供了有效途径,并为同时改善光催化剂的转化率和选择性提供了借鉴.

超声引导泡沫硬化治疗静脉曲张术后复发溃疡的疗效分析

目的探讨超声引导泡沫硬化(UGFS)治疗下肢静脉曲张术后复发溃疡的临床疗效。方法选取2014年6月-2015年12月河北医科大学第一医院收治的行UGFS治疗下肢静脉曲张术后复发溃疡的患者45例,对患者临床资料进行回顾性分析,观察不同组别患者泡沫硬化剂的用量及溃疡愈合时间的差别。结果 3种术式患者术后复发年限比较无差异(P>0.05)。浅静脉+交通静脉治疗组泡沫硬化剂平均用量高于浅静脉组与交通静脉组(P<0.05),C5组与C6组患肢溃疡愈合时间比较有差异(P<0.05)。3组不同性别和肢体溃疡愈合时间比较无差异(P>0.05)。体重指数、年龄与溃疡愈合时间呈正相关(P<0.05)。患者术后并发症血栓性浅静脉炎最常见,发生率为11.1%。有血栓性浅静脉炎患者泡沫硬化剂平均用量高于无血栓性浅静脉炎患者(P<0.05)。术后12个月病变血管完全或部分再通率为20.0%(9/45)。结论 UGFS治疗下肢静脉曲张术后复发溃疡具有治愈率高、并发症少等特点,是一种简便、精准、有效的诊疗方法。

中国软件学院国际合作项目类型探析（英文）

在全球化和软件行业需求的双重影响下,中国的软件学院与国外高校开展了形式多样的国际合作项目,包括体验式项目、学位项目以及联合合作项目。文章分析各类国际合作项目的特点,并根据这些特点探索出适合中国软件学院开展国际合作项目的方法。

基于计算机辅助测量对正常学龄前儿童肺血管体积的研究

目的基于胸部CT定量测量探讨正常学龄前儿童肺内血管体积(IPVV)随生长发育的变化趋势。方法回顾性收集"数字肺"影像数据库2014年1月至2017年5月行胸部CT检查且结果正常的407例正常学龄前儿童的CT资料,男236例、女171例,月龄36(21,50)个月,范围1~72个月。使用"数字肺"肺血管自动检测工具分割肺内血管,并得到全肺、右肺、左肺及各肺叶的IPVV,计算IPVV上/下及IPVV左/右。根据月龄将受试者分为婴儿期(0~12个月)、幼儿期(13~36个月)和学龄前期(37~72个月),分别为30例(男17例、女13例)、175例(男95例、女80例)、202例(男124例、女78例)。用Spearman相关性分析评价IPVV与月龄的相关性。采用单因素方差分析或Kruskal-WallisH检验比较不同月龄段间、采用独立样本t检验或Mann-WhitneyU检验比较不同性别间IPVV、IPVV上/下及IPVV左/右的差异,并建立各个月龄段正常学龄前儿童IPVV的正常参考值范围。结果全肺、右肺、左肺及各个肺叶的IPVV与月龄均呈正相关,相关系数男性为0.638~0.820,女性为0.683~0.791(P均<0.001)。0~12个月的男、女童间全肺、右肺、左肺及各肺叶IPVV差异均无统计学意义(P均>0.05),13~36个月男、女童间全肺、右肺、左肺及各肺叶IPVV差异均有统计学意义(P均<0.05),37~72个月男、女童间全肺、右肺、左肺、双肺上叶IPVV差异均有统计学意义(P均<0.05)。男、女童3个月龄段间右肺IPVV上/下(χ^(2)=14.00、12.87,P=0.001、0.002)和左肺IPVV上/下差异均有统计学意义(χ^(2)=6.65、22.84,P=0.036、<0.001),且随着月龄的增长呈递减趋势;同月龄段男、女童间IPVV上/下差异无统计学意义(P均>0.05)。不同月龄段及各月龄段不同性别间IPVV左/右差异均无统计学意义(P均>0.05)。最后计算出婴儿期、幼儿期、学龄前期不同性别IPVV的正常参考值范围。结论正常学龄前儿童肺血管的增长与月龄呈正相关,婴儿期男、女间IPVV无显著差异,而在幼儿期和学龄前期男童IPVV大于女童;下肺IPVV增长的速度快于上肺,而在左右肺之间无明显差异。

弛豫量热技术研究固体材料低温比热性质

比热是物质最基础的热力学性质,通过测量并研究物质低温比热不仅可以计算得到熵、焓、吉布斯自由能等热力学函数,还可以获得有关物质物理性质、能量、结构及相变的信息,为相关热力学问题的探索与研究提供重要依据。低温比热测量一般有绝热量热、交流量热和弛豫量热三种技术;其中弛豫量热因测试样品用量少、测量温区低、测量准确度高、操作方便、有商品化仪器可得等优点,已成为近些年来发展最快、应用最广泛的低温比热测量技术。为了使研究者们更全面地了解这种量热技术,本文详细介绍了弛豫量热技术的测量原理、发展历程以及测量技术的研究进展,并结合当前热门研究领域,简要概述了国内外学者利用弛豫量热技术测量材料低温比热并研究相关热力学性质的最新工作进展。

3D dahlia-like NiAl-LDH/CdS heterosystem coordinating with 2D/2D interface for efficient and selective conversion of CO_(2)

Developing photocatalyst with high activity,superior stability and prominent selectivity for CO_(2)conversion is of great importance for the target of carbon neutralization.Herein,3 D dahlia-like NiAl-LDH/CdS heterosystem is developed through in-situ decoration of exfoliated CdS nanosheets on the scaffold of NiAl-LDH and the on-spot self-assembly.The formation of a hierarchical architecture collaborating with well-defined 2 D/2 D interfacial interaction is constructed by optimizing the ratio of CdS integrated in the formation of the heterojunction.The light-harvesting capacity of NiAl-LDH/CdS is improved by this unique scaffold,and the charge transfer between NiAl-LDH and CdS is effectively facilitated by virtue of the unique 2 D/2 D interface.As a result,the 3 D hierarchical NiAl-LDH/CdS heterosystem presents 12.45μmol g^(-1)h^(-1)of CO production(3.3 and 1.6 folds of pristine NiAl-LDH and CdS) with 96% selectivity and superior stability.This 3 D hierarchical design collaborating with 2 D/2 D interfacial interaction provides a new avenue to develop ideal catalysts for artificial photosynthesis.

Thermodynamic insights into n-alkanes phase change materials for thermal energy storage

n-Alkanes have been widely used as phase change materials(PCMs) for thermal energy storage applications because of their exceptional phase transition performance, high chemical stability, long term cyclic stability and non-toxicity. However, the thermodynamic properties, especially heat capacity, of n-alkanes have rarely been comprehensively investigated in a wide temperature range, which would be insufficient for design and utilization of n-alkanes-based thermal energy storage techniques. In this study, the thermal properties of n-alkanes(C;H;-C;H;), such as thermal stability, thermal conductivity, phase transition temperature and enthalpy were systematically studied by different thermal analysis and calorimetry methods, and compared with previous results. Thermodynamic property of these n-alkanes was studied in a wide temperature range from 1.9 K to 370 K using a combined relaxation(Physical Property Measurement System, PPMS), differential scanning and adiabatic calorimetry method, and the corresponding thermodynamic functions, such as entropy and enthalpy, were calculated based on the heat capacity curve fitting. Most importantly, the heat capacities and related thermodynamic functions of n-heneicosane and n-docosane were reported for the first time in this work, as far as we know. This research work would provide accurate and reliable thermodynamic properties for further study of n-alkanes-based PCMs for thermal energy storage applications.

Applications of low temperature calorimetry in material research

Low temperature calorimetry is an experimental method of heat capacity measurements, and heat capacity is one of the most important and fundamental thermodynamic properties of substances. The heat capacity can provide an average evaluation of the thermal property of a sample since it is a bulk property of substances. In the other hand, the condensed states of substances could be mainly controlled by the molecular motions, intermolecular interactions, and interplay among molecular structures. The physical property reflected in a material may be closely related to the energy changes in these three factors, which can be directly observed in a heat capacity curve. Therefore, low temperature calorimetry has been used not only to obtain heat capacity, entropy, enthalpy and Gibbs free energy, but also to investigate and understand lattice vibrations, metals, superconductivity, electronic and nuclear magnetism, dilute magnetic systems and structural transitions. In this review, we have presented the concept of low temperature calorimetry and its applications in the related field of material researches,such as nano-materials, magnetic materials, ferroelectric materials, phase change materials and other materials.