基于紫外可调谐激光吸收光谱技术的甲烷/空气平面预混火焰温度测量研究

火焰温度是燃烧领域最重要的宏观物理量之一,使用紫外可调谐激光吸收光谱技术,以火焰中的OH自由基作为测量对象对甲烷/空气平面预混火焰进行了温度测量。首先使用平面激光诱导荧光(PLIF)技术对甲烷/空气平面预混火焰不同燃烧工况条件下火焰中的OH基分布进行了测量,选取火焰中OH基分布均匀工况进行了紫外吸收光谱温度测量。通过LIFBASE仿真计算,综合考虑温度测量灵敏度、测量信噪比等因素,选择OH基A-X(0,0)吸收带中的P_1(2)和Q_1(8)两支谱线作为被测跃迁。测量时使用Nd∶YAG激光器泵浦染料激光器,经倍频后输出308~311nm紫外可调谐激光。通过染料激光器以0.4pm为步长进行激光波长调谐,分别扫描获得两条吸收谱线的吸收峰线型。对实验数据进行voigt拟合后,通过计算两条谱线的积分吸收值之比,获得了平面预混火焰中的温度信息。分别测量了燃烧器表面不同水平位置与燃烧器中心不同高度处的火焰温度。测量结果与文献报道的采用同样结构燃烧器,通过其他光谱技术获得的测量结果进行了横向对比。在OH基浓度较高的火焰锋面区域测温结果吻合度较高,验证了该技术测量结果的可信度。由于其测量对象与双线OH-PLIF测温的一致性,该技术未来可作为局部温度测量方法,进一步应用于对双线PLIF等二维火焰温度空间分布测量结果的标定当中。     

小分子改性的聚合物固体染料激光特性研究

PMMA是常用的固体染料基质，通过添加乙醇进行改性，形成MPMMA，并对其透过率、荧光光谱、激光光谱和斜率效率进行研究.乙醇对染料的宽带荧光谱的影响较小，荧光谱的带宽为～50nm；激光光谱半宽为7—9 nm，激光光谱的峰值波长随乙醇体积比改变而相应的移动；乙醇体积比存在一个最佳值(15%)，使介质在600 nm—750 nm波段具有最好的透过率(～90%)，并且获得最的斜率效率，其值为49.7%. 关键词： 固体染料 改性聚甲基丙烯酸甲酯 宽带激光 PM567     

Solid State Dye Lasers Based on Coumarin 440 and Pyrromethene 567 Codoped Polymethyl Methacrylate

Laser dye coumarin 440（C440） is codoped with pyrromethene 567 （PM567） into polymethyl methacrylate （PMMA） The effects of C440 concentration on the performance of the solid state dye medium, including spectra property, slope efficiency and photostability, are studied. When C440 is codoped with PM567 at the same concentration 1 × 10^-4 mol/L, the highest efficiency and photostability can be obtained. Compared with the medium based on pure PM567 doped PMMA, about 50% increase in slope efficiency and at least five-fold enhancement in the photostability are observed.     

两性离子水凝胶的制备及生物医学应用

两性离子水凝胶是一类含有两性离子聚合物的凝胶材料,其分子结构中的阴阳离子基团能与水分子紧密结合,形成致密的水合层。这种静电诱导水合作用使得两性离子水凝胶具有极低的生物黏附性,能有效抵抗非特异性蛋白、细胞、细菌等的黏附,具有极低的免疫原性。这些特性使得两性离子水凝胶在生物医用领域有广阔的应用前景。本综述首先介绍了两性离子水凝胶的结构及性质,然后概述了其分类和制备方法,并进一步总结了其在组织工程、药物载体、创伤敷料、生物传感器、医疗器械水凝胶涂层等生物医学领域中的应用。最后展望了两性离子水凝胶未来的发展方向。     

PM567-Doped solid dye lasers based on PMMA

Polymers are a kind of attractive hosts for laser dyes due to their high transparency in both pumping and lasing ranges and superior optical homogeneity. In this paper solid dye samples based on polymethyl methacrylate (PMMA) doped with different concentrations of 1, 3, 5, 7, 8 -pentamethyl-2, 6-diethylpyrromethene-BF$_{2 }$ (PM567) are prepared. The absorption, fluorescence and lasing spectra of the samples are obtained. Wide absorption and fluorescence bands are obtained and a red shift of the maxima of the lasing emission spectra is observed. With the second-harmonic generation of Q-switched Nd:YAG laser (532\,nm, $\sim $20\,ns) pumping the samples longitudinally, the slope efficiencies of the samples are obtained. There is an optimal dye concentration for the highest slope efficiency when the pumping energy is lower than some typical value ($\sim $250\,mJ), and the highest slope efficiency 35.6{\%} is obtained in the sample with a dye concentration of $2\times10^{ - 4}$\,mol/L. Pumping the samples at a rate of 10Hz with a pulse energy as high as 200\,mJ (the fluence is 0.2\,J/cm$^{2})$, the output energy drops to one-half of its initial value after approximate 15500 pulses and the normalized photostability is 5.17\,GJ/mol. A kind of solid dye laser which could have some applications is built.     

海藻糖改性聚乙烯醇及其防雾/防霜涂层

以聚乙烯醇和羧基化海藻糖为原料合成了聚乙烯醇-g-海藻糖(PVA-g-Tre), 将接枝物与少量乙二醇二甲基丙烯酸酯混合, 通过光引发聚合制备了亲水性半互穿网络防雾/防霜涂层. 通过核磁共振氢谱和傅里叶变换红外光谱对PVA-g-Tre的化学结构进行了表征, 利用原子力显微镜、 水接触角测试仪、 拉曼光谱等分析了涂层表面的粗糙度、 润湿性及水与大分子之间的氢键作用, 并考察了涂层的透光性和防雾及防霜性能. 结果表明, 含有不同海藻糖接枝率PVA-g-Tre的涂层表面粗糙度较低且透光率好, 与含有PVA的涂层相比, 引入海藻糖提高了PVA-g-Tre涂层的亲水性和润湿性, 使其同时具有良好的防雾和防霜性能.     

血红蛋白片段的合成及生物活性

采用多肽固相合成方法, 以Wang 树脂为载体, Fmoc为N-端氨基酸保护基, HOBt-HBTU为缩合试剂, 合成了一系列血红蛋白α链的片段, 产物经RP-HPLC和质谱进行了确定. 生物活性研究结果表明, 该系列多肽具有较高的血管紧张素Ⅰ转换酶抑制活性, 但不具有α-葡萄糖苷酶抑制活性.     

Boc-L-甲基苯丙氨酸的合成与拆分

利用Boc-2-氨基丙二酸二乙酯和甲基苄溴为原料, 合成邻位、间位、对位甲基取代的Boc-苯丙氨酸乙酯, 经枯草杆菌蛋白酶拆分得到对应的Boc-L-甲基苯丙氨酸. 通过红外光谱、核磁共振、质谱及旋光度分析对3种物质的结构进行了表征.     

Solid Dye Lasers Based on 2-Hydroxypropyl Methacrylate and Methyl Methacrylate Copolymers

Polymers are a kind of attractive hosts for laser dyes because of their superior optical homogeneity, and high transparency in pumping and lasing range. Copolymers usually have higher damage threshold and better photostability than mono-polymers. Solid dye samples based on copolymer of methyl methacrylate （MMA） with 2-hydroxypropyl methacrylate （HPMA） doped with 1-, 3-, 5-, 7-, 8-pentamethyl-2, 6-diethylpyrromethene-BF2 （PM567） are prepared. Spectra and lasing properties of the samples are studied. Compared to the samples based on monopolymer polymethyl methacrylate （PMMA）, enhanced slope efficiency and photostability are obtained in the copolymers. The highest slope efficiency is 45.1%, and nearly one-fold increase of photostability is obtained. The longest useful lifetime of 4390 pumping pulses is presented with the pump energy as high as 183 mJ per pulse at repetition rate of 10 Hz. The results indicate that the laser performances of solid dye mediums can be greatly increased using copolymer of MMA with HPMA as host.     

环肽类组蛋白去乙酰化酶抑制剂

组蛋白乙酰化转移酶(HAT)和组蛋白去乙酰化酶(HDAC)调节组蛋白乙酰化程度，HDAC在基因表达和染色体形成等方面起着重要的调节作用。HDAC抑制剂能够引起肿瘤细胞生长停滞、诱导肿瘤细胞分化和调亡。通过对各种HDAC抑制剂结构及作用机制的研究有助于该类药物在临床上的应用和拓宽癌症治疗的适用范围。本文概述了近年来天然及合成的环肽类组蛋白去乙酰化酶抑制剂的研究进展。