2,5-di-[2-(3,5-bis(2-pyridylmethyl)amine -4-hydroxy-phenyl) ethylene] pyrazine zinc complex as fluorescent probe for labeling proteins

The binding characteristics between 2,5-di-[2-(3,5-bis(2-pyridylmethyl)amine -4-hydroxy-phenyl) ethylene] pyrazine (1) or its complex (1-Zn) and serum albumins were studied by fluorescence spectroscopy in pH 7.4 aqueous solution. 1-Zn emitted weak fluorescence at 580 nm in a pH 7.4 Tris-HCl buffer solution when excited at 435 nm, however, the fluorescence intensity increased upon addition of serum albumins with the blue shift of emission peak to 524 nm. The binding constants were estimated as 8.40 x 10(7) and 3.03 x 10(6)mol(-1)L for bovine serum albumin (BSA) and human serum albumin (HSA) respectively, and the number of binding sites was 1 for each. The quenching mechanism of fluorescence of serum albumins by 1-Zn was considered as a static quenching process. The binding distance between 1-Zn and serum albumins and the energy transfer efficiency were obtained based on the theory of F?rester spectroscopy energy transfer. The effect of 1-Zn on the conformation of serum albumins was further analyzed using synchronous fluorescence spectrometry. The experiment results clearly showed that 1-Zn is a highly sensitive protein sensor.     

北京周口店洞穴发育及其与古人类生活的关系

周口店北京猿人化石产地,附近有四个岩溶洞穴(即笫1地点猿人洞、第15地点洞穴、笫4地点新洞和山顶洞),为古人类居住过.这些洞穴的发育深受地质构造控制,按其形态主要分垂直型和水平型两类.其中猿人洞规模最大,是复杂的垂直型溶洞系统,堆填了40余米厚的洞穴地层.根据岩溶洞穴发育的理论,洞内堆积物与洞外堆积物的对比分析,以及绝对年龄测定资料,并参考了过去的发掘记录,可以将猿人洞穴的演化过程大致分为5个阶段,每个阶段均与古人类的生活活动有密切的关系.     

Study of interaction of a fluorescent probe with DNA

The zinc complex of 2-[2-(3, 5-bis(2-pyridylmethyl)aminomethyl-4-hydroxy-phenyl) ethylene]-5-methylpyrazine (1) could bind with the calf thymus deoxyribonucleic acid (ct-DNA). The binding behaviors between them were studied by fluorescence and absorption spectral assay. The absorption titration of 1-Zn with ct-DNA showed no bathochromic shift and hypochromic effect. No anisotropy increase was observed when ct-DNA was added to 1-Zn solution. They both proved the lack of intercalation interaction between 1-Zn and ct-DNA. The ionic strength experiment, Scatchard plot, study of interaction between 1-Zn and denatured ct-DNA all revealed that the interaction mode between 1-Zn and ct-DNA was electrostatic interaction. Binding constant was estimated to be 7.96×10⁴ L moL⁻¹.     

高活性硫化铅电极的制备及在量子点敏化太阳能电池中的应用

为了提高量子点敏化纳晶薄膜太阳能电池的光电转换效率,我们通过连续在酸和多硫溶液中处理铅片制备了对多硫电解液具有高电催化活性的硫化铅电极. 通过电化学阻抗谱测试评价所制备硫化铅电极的催化活性,从而确定制备高效硫化铅电极的最佳条件. 以在最佳条件下制备的硫化铅为对电极、CdSe量子点敏化TiO₂纳晶薄膜为工作电极和多硫电解液组装成量子点敏化太阳能电池. 光电性能测试结果表明所制备的电极具有良好的催化活性和光电转换性能. 与已报导的方法相比,新方法大幅度地减少制备过程所需的时间,但却提高了所制备的硫化铅对电极的催化活性. 通过X射线衍射和扫描电镜测试表征了硫化铅的生成过程,探讨了催化活性提高的原因.     

钙钛矿型氧载体SrCo_(0.8)Fe_(0.2)O_(3-δ)制氧性能的实验研究

钙钛矿型金属氧化物是优良的制备供富氧燃烧所需的O_2/CO_2的氧载体,本文采用柠檬酸法制备系列SrCo_(1-x)Fe_xO_(3-δ)(x=0.2,0.4,0.6,0.8)钙钛矿型氧化物,并采用X射线衍射分析来表征SrCo_(0.8)Fe_(0.2)O_(3-δ)(SCF182)反应前后的物相变化和晶体结构.同时在固定床上选择不同的运行条件对SCF182的释氧性能进行研究,包括吸附温度、吸附时间、脱附温度和循环特性.结果表明,SCF182的最佳吸附温度和脱附温度均为850℃,最佳吸附时间为1 h,循环性能良好,是可以为富氧燃烧提供稳定的O_2/CO_2循环气体的良好材料。     

Antibody and DNA dual-labeled gold nanoparticles: Stability and reactivity

Gold nanoparticles labeled by both antibody (IgG) and single stranded DNA (ss-DNA) have been synthesized and characterized. The stability and reactivity of the dual-labeled nanoparticles were compared with the conventional IgG or ss-DNA modified nanoparticles. It was found that the IgG adsorption significantly improved the stability of the nanoparticles in aqueous solution, which is beneficial for attaching ss-DNA. The presence of IgG also effectively prohibits the desorption of ss-DNA against dithiothreitol (DTT) displacement. The coverage on dual-labeled nanoparticles was found to be 50 ± 15 ss-DNA/nanoparticle and 10 ± 2 IgG/nanoparticle, respectively, compared to the value of 70 ± 15 ss-DNA/nanoparticle of only ss-DNA-labeled gold nanoparticles. Dot-immuno and cross-linking experiments confirmed that both the IgG and ss-DNA retained their bioactivity on the nanoparticle surface. The dual-labeled nanoparticles have potential to be used as novel bio-probes for ultrasensitive detection.     

Special Pore-Space-Partition CoFePBA Hollow Framework Realizing High-Performance Glucose Sensing

In this work for the first time pore-space-partition (PSP)-CoFePBA hollow framework is elaborately designed and successfully obtained via self-template internal dissolution strategy. As is demonstrated by our previous report, Prussian blue analogue (PBA) with hollow morphology is very beneficial to improve sensing performance. As expected, the PSP-CoFePBA hollow framework in this work exhibits far superior glucose sensing performance compared with classic CoFePBA nanoparticles and nanoboxes as well as most of reported PBA-based glucose sensors. Herein, very high sensitivity of 1184.18 μA mM⁻¹ cm⁻² and 267.63 μA mM⁻¹ cm⁻² in the concentration range of 5–325 μM and 325–1025 μM, respectively, as well as low detection limit of 0.4 μM (S/N=3) and high stability can be observed. In a word, this work proposes and develops a simple and general synthetic strategy for constructing PBA-based hollow material, that will be very helpful in this field.     

二氧化钛基Z型异质结光催化剂

二氧化钛(TiO_2)因廉价、无毒、化学性质稳定以及具有较强的光催化氧化还原能力,在光催化领域占据着重要的地位。然而,可见光利用率低以及光生电子-空穴对的快速复合是限制其应用的2个主要因素。二氧化钛基Z型异质结作为一种新型光催化剂,既改善了二氧化钛的2个缺陷,又表现出比TiO_2更强的氧化或还原能力。本文概括了TiO_2光催化剂、异质结光催化剂和TiO_2基Z型光催化剂的能带排列和电子传递原则,探讨了Z型异质结和type-Ⅱ异质结的异同点以及区分方法,并归纳总结了TiO_2基Z型异质结在光催化领域中的应用。