Impacts of the Wenchuan Earthquake on the Giant Panda Nature Reserves in China

Ministry of Science and Technology of China [2008BAK47B02, 2008BAC44B04, 2008BAK50B06, 2008BAC43B01, 2006BAC08B06]

Structure and mechanical properties of extruded Mg-Gd based alloy sheet

The Mg-8Gd-2Y-1Nd-0.3Zn-0.6Zr (wt.%) alloy sheet was prepared by hot extrusion technique, and the structure and mechanical properties of the extruded alloy were investigated. The results show that the alloy in different states is mainly composed of alpha-Mg solid solution and secondary phases of Mg5RE and Mg24RE5 (RE = Gd, Y and Nd). At aging temperatures from 200 degrees C to 300 degrees C the alloy exhibits obvious age-hardening response. Great improvement of mechanical properties is observed in the peak-aged state alloy (aged at 200 degrees C for 60 h), the ultimate tensile strength (sigma(b)), tensile yield strength (sigma(0.2)) and elongation (epsilon) are 376 MPa, 270 MPa and 14.2% at room temperature (RT), and 206 MPa. 153 MPa and 25.4% at 300 degrees C, respectively, the alloy exhibits high thermal stability.

Investigation on internal electric field distribution of organic light-emitting diodes (OLEDs) with Eu2O3 buffer layer

We have found that organic light-emitting diode (OLED) performance was highly improved by using europium oxide (Eu2O3) as a buffer layer on indium tin oxide (ITO) in OLEDs based on tris-(8-hydroxyquinoline) aluminium (Alq(3)), which showed low turn-on voltage, high luminance, and high electroluminescent (EL) efficiency. The thickness of Eu2O3 generally was 0.5-1.5 nm. We investigated the effects of Eu2O3 on internal electric field distributions in the device through the analysis of current-voltage characteristics, and found that the introduction of the buffer layer balanced the internal electric field distributions in hole transport layer (HTL) and electron transport layer (ETL), which should fully explain the role of the buffer layer in improving device performance. Our investigation demonstrates that the hole injection is Fowler-Nordheim (FN) tunnelling and the electron injection is Richardson-Schottky (RS) thermionic emission, which are very significant in understanding the operational mechanism and improving the performance, of OLEDs.

VUV-UV photoluminescence spectra of strontium orthophosphate doped with rare earth ions

The measurements of VUV-UV photoluminescence emission (PL) and photoluminescence excitation (PLE) spectra of rare earth ions activated strontium orthophosphate [Sr-3(PO4)(2):RE, RE = Ce, Sm, Eu, Tb] are performed. Whenever the samples are excited by VUV or UV light, the typical emission of Ce-3+,Ce- Sm3+, Eu3+, Eu2+ and Tb3+ ions can be observed in PL spectra, respectively. The charge transfer bands (CTBs) of Sm3+ and Eu3+ are found, respectively, peaking at 206 and 230nm. The absorption bands peaking in the region of 150-160 nm are assigned to the host lattice sensitization bands, i.e., the band-to-band transitions of PO43- grouping in Sr-3(PO4)(2). It is speculated that the first f-d transitions of Sm3+ (Eu3+), and the CTB of Tb3+ are, respectively, located around 165 (14 3) and 167 urn by means of VUV-UV PLE spectra and relational empirical formula, these f-d transitions or CT bands are included in the bands with the maxima at 150-160 nm, respectively. The valence change of europium from trivalent to divalent in strontium orthophosphate prepared in air is observe by VUV-UV PL and PLE spectra.

Scanning electrochemical microscopy study of electron transfer across the water/1,2-dichloroethane interface induced by common ions

In this work, we report the reverse electron transfer reaction between TCNQ in 1, 2-dichloroethane (DCE) and ferrocyanide in water. This process is a thermodynamic unfavorable reaction and the reverse electron transfer reaction can only be obtained by scanning electrochemical microscopy(SECM) in the presence of suitable potential-determining ions, which govern the interfacial potential difference. In our case, the potential determining ions are tetrabutylammonium ion(TBA(+)) and tetraphenylarsonium ion (TPAs+). The effects of the concentrations of TBA(+) and TPAs+ in two phases and other parameters have been studied in detail. The apparent heterogeneous rate constants(k(i)) were obtained under different values of K-p(K-p=c(i)(w)/c(i)(o)) for both cases by fitting the SECM approach curves with theoretical ones and the results showed that they were controlled by the interfacial potential differences. The relationship between apparent heterogeneous rate constants and the interfacial potential differences obeys Butler-Volmer theory.

应用扫描电化学显微镜研究水/1,2-二氯乙烷界面上离子诱导的电子转移反应

应用扫描电化学显微镜和微电极技术研究了水 / 1,2 二氯乙烷界面上的反向电子转移反应 .分别以K4 Fe(CN) 6和 7,7,8,8 四氰代二甲基苯醌 (TCNQ)作为水相和有机相的电活性物质 ,通过选择合理的共同离子 (TPAs+与TBA+)来控制界面电位差 ,实现了这一在热力学上通常不可能实现的反向电子转移反应 .利用扫描电化学显微镜给出的正负反馈信息 ,研究了界面电位差驱动的液 /液界面上的电子转移反应 ,并进一步得到了在不同的共同离子浓度比时 ,此异相界面反应速率常数kf 为 1 3× 10 -31 8× 10 -2 cm/s(共同离子为TBA+)和 2 5× 10 -32 8× 10 -2 cm/s(共同离子为TPAs+) .验证了此反应速率常数kf 是由界面电位差所决定的 .在此实验条件下 ,此反应速率常数kf 与界面电位差的关系遵守Butler Volmer公式 .

双包层传像光纤光子器件材料及工艺的研究

本文结合双包层传像光纤光子器件材料和工艺方面的研究,阐述了双包层传像光纤光子器件的工艺原理;从材料和工艺等方面分析了影响双包层传像光纤光子器件质量的一些因素;提出了必要的改进措施;并给出了双包层传像先纤光子器件有关性能的阶段性研究成果。

玻碳电极上六氰亚铁酸钯膜的现场FTIR光谱电化学研究

本文报道六氰亚铁酸钯膜修饰电极在HCL，KCL和NaCl溶液中的现场反射FTIR光谱电化学研究，结果表明该修饰膜具有内外两层结构，分别为Pd2Fe(CN)6和M2PdFe(CN)6，其中M为支持电解质一价阳离子．在1mol/L NaCl中，内层的氧化电位Em＝0.87V(vs．Ag/AgCl)，外层为0.77V．在1mol/L HCl或KCl中两层的氧化还原波重叠为一个大CV波峰而难以分辨，然而现场FTIR光谱电化学清晰地分辨出这两种结构在所有3种溶液中CN的不同振动频率，发现H+离子是最佳的支持电解质，能使这两种结构同时发生氧化反应

Novel morphology in ring-banded spherulites from single-phase mixtures of poly(epsilon-caprolactone) with poly(styrene-co-acrylonitrile)

Novel morphology of ring-banded spherulites in the surface of poly(epsilon-caprolactone)/poly(styrene-co-acrylonitrile) (PCL/SAN) blends was discovered and studied by SEM and TEM. The ring-banded spherulites separate into those exhibiting a very dark contrast, of relatively regular bundles of lamellae and others appearing with a much brighter intensity, of a coarse and irregular aggregates of lamellae. The origin of the novel morphology is not due to different crystalline structures as in the case of isotactic polypropylene because only one crystal structure exists in PCL/SAN blends. The formation may reflect whether spherulites in PCL/SAN blends are nucleated at the bottom surface or at the top (free) surface.

甲烷与二氧化碳重整制取合成气反应的研究 (I)Sr_(1-x)La_xNiAl_(11)O_(19)催化剂的物理化学性质表征

合成了具有磁铅石结构的Ｓｒ１－ｘＬａｘＮｉＡｌ１１Ｏ１９系列催化剂，并用ＸＲＤ、ＵＶ－ＤＲＳ、Ｈ２－Ｏ２滴定及Ｐｙ－ＩＲ等方法对其体相及表面性质进行了表征．结果表明，Ｌａ３＋离子能够同晶取代Ｓｒ２＋离子进入催化剂晶格内部；随着Ｌａ３＋含量增加，催化剂的结晶度提高，从而降低了镍的还原性，并使金属镍在表面上的分散度略有提高；在ＳｒＮｉＡｌ１１Ｏ１９中掺入Ｌａ３＋离子，能够抑制晶体沿ｃ轴方向的生长，提高其比表面积；同时Ｌａ３＋离子对Ｓｒ２＋离子的调变，减少了表面的酸中心数目

合成环化聚异戊二烯的新方法

在二甲苯中，以氯化钕异丙醇配合物－三乙基铝（Ａｌ）为催化剂引发异戊二烯（Ｉｐ）顺式聚合，在转化率小于２０％时，引入烯丙基氯（Ｃｌ），当Ｃｌ／Ａｌ摩尔比为１．０～６．０时，可制得环化度为６６％～１００％，Ｔｇ为６０～７０℃的环化聚异戊二烯（ＣＰＩｐ）。实验结果表明，随Ｃｌ／Ａｌ摩尔比的增加，Ｉｐ转化率升高，产物［η］降低。同时，用ＩＲ，１Ｈ－ＮＭＲ，ＤＳＣ等测试方法对环化产物的结构和性能进行了表征。