铬系催化剂聚合1,3-双烯烃的研究

铬系催化剂是合成1,2-聚丁二烯和3,4-聚异戊二烯的一种主要催化剂体系，1,2-聚丁二烯和3,4-聚异戊二烯是制造高性能轮胎的重要原料。本论文研究了以含氮化合物和含磷化合物为配体的铬催化剂合成1,2-聚丁二烯和3,4-聚异戊二烯的反应规律。 1. 以邻菲咯啉为配体的铬催化剂在己烷中50℃下可获得1,2-结构、顺-1,4-结构和反-1,4-结构单元含量分别约为50%、30%和20%，分子量呈双峰分布的聚丁二烯。改变聚合温度，可有效控制聚合物的1,2-结构含量和分子量及分布。催化剂通过预陈化方式，可有效抑制低聚物的生成。 2. 以亚磷酸二烷基酯为配体的铬催化剂是合成1,2-聚丁二烯的高效催化剂，所得聚合物具有高的1,2-结构含量（> 78%）。改变烷基铝和亚磷酸二烷基酯的结构，可以得到高熔点或低熔点间同1,2-聚丁二烯和无规1,2-聚丁二烯。催化剂以现配方式的活性最高。 3. 以磷酸三苯酯为配体的铬催化剂可获得间同1,2-聚丁二烯，而聚合物中含有低聚物。催化剂以现配方式的活性最高。聚合物的熔点，低聚物的含量与磷酸三苯酯的结构有一定的关系。 4. 以邻菲咯啉为配体的铬催化剂在50℃下聚合异戊二烯，具有高的催化活性，可获得3,4-结构含量约67%的高分子量无规3,4-聚异戊二烯。催化剂的组成对聚合物的微观结构无明显影响。改变聚合温度，可有效控制聚合物的3,4-结构含量和分子量及分布。

铁系催化剂聚合1，3-双烯烃的研究

1，2-聚丁二烯和3，4-聚异戊二烯是制造高性能轮胎的原料。本论文研究了以含磷化合物为第三组份的铁催化剂合成1，2-聚丁二烯和3，4-聚异戊二烯的反应规律：1．以二乙基亚磷酸酷为第三组份的铁催化剂可在己烷中，较高温度（50℃）下聚合1，3-丁二烯。通过控制催化剂组份的配比，可制备间同和无规1，2-聚丁二烯。所得间同1，2-聚丁二烯的1，2-结构含量为91％，间规度为90％；所得无规1，2-聚丁二烯的硫化胶具有优异的抗干、湿滑性能。2．以三苯基磷酸酷为第三组份的铁催化剂是合成高间同1，2一聚丁二烯的高效催化剂。所得聚合物具有高的1，2-结构含量（ca.95％），高的间规度（ca.95％）。聚合物的微观结构与催化剂组成等反应因素无关。3．以二烷基亚磷酸醋为第三组份的铁催化剂可在己烷中，较高温度（50℃）下聚合异戊二烯。二烷基亚磷酸醋中烷基影响聚合活性的顺序为乙基一甲基＞正丁基＞异辛基。所得聚异戊二烯的3，4（含1，2）结构含量保持在60％左右，不受反应条件的影响。4．改性甲基铝氧烷（MMAO）活化的铁催化剂聚合异戊二烯，在相当低的MMAO用量下（Al／Fe=20，摩尔比）即有高的催化活性。溶剂影响聚合活性的顺序为甲苯＞环己烷＞己烷＞二氯甲烷。所得聚异戊二烯的3，4（含1，2）结构含量稳定在60％。

1.3μm InGaAs/InAs/GaAs Self-Assembled Quantum Dot Laser Diode Grown by Molecular Beam Epitaxy

The growth of multi-layer InGaAs/InAs/GaAs self-assembled quantum dots （QDs） by molecular beam epitaxy （MBE） is investigated,and a QD laser diode lasing at 1.33μm in continuous operation mode at room temperature is reported. The full width at half maximum of the band edge emitting peaks of the photoluminescence （PL） spectra at room temperature is less than 35meV for most of the multi-layer QD samples,revealing good,reproducible MBE growth conditions. Moreover,atomic force microscopy images show that the QD surface density can be controlled in the range from 1×10^10 to 7 ×10^10 cm^-2 . The best PL properties are obtained at a QD surface density of about 4×10^10cm^-2. Edge emitting lasers containing 3 and 5 stacked QD layers as the active layer lasing at room temperature in continuous wave operation mode are reported.

Surface Morphology and Photoluminescence of 1.3 μm Wavelength In(Ga)As/GaAs Quantum Dots

Self-organized In_(0.5)Ga_(0.5)As/GaAs quantum island structure emitting at 1. 35 (im at room temperature has been successfully fabricated by molecular beam epitaxy (MBE) via cycled (InAs)_1/( GaAs)_1 monolayer deposition method. Photoluminescence (PL) measurement shows that very narrow PL linewidth of 19.2 meV at 300 K has been reached for the first time, indicating effective suppression of inhomogeneous broadening of optical emission from the In_(0.5)Ga_(0.5)As islands structure. Our results provide important information for optimizing the epitaxial structures of 1.3 μm wavelength quantum dot (QD) devices.

低阈值1.3μm InGaAsP/InP应变补偿多量子阱DFB激光器LP-MOCVD生长

报道了用低压－金属有机化学气相淀积(LP-MOCVD)方法制作1.3μm应变补偿多量子阱结构材料。X射线双晶衍射摇摆曲线可清晰地看到±4级卫星峰和卫星峰间的Pendellosong条纹。整个有源区的平均应变量几乎为零。用掩埋异质结(BH)条形工艺制备的含一级光栅的DFB激光器室温下阈值电流2～4mA,外量子效率0.33mW/mA,线性输出光功率达30mW,边模抑制比(SMSR)大于35dB。20～40℃下的特征温度T_0为67K。

Photoluminescence characterization of 1.3 mu m In(Ga)As/GaAs islands grown by molecular beam epitaxy

1.3 mum wavelength In(Ga)As/GaAs nanometer scale islands grown by molecular beam epitaxy (MBE) were characterized by photoluminescence (PL) and atomic force microscopy (AFM) measurements. It is shown that inhomogeneous broadening of optical emission due to fluctuation of the In0.5Ga0.5As islands both in size and in compositions can be effectively suppressed by introducing a AlAs layer and a strain reduction In0.2Ga0.8As layer overgrown on top of the islands, 1.3mum emission wavelength with narrower line-width less than 20meV at room temperature was obtained.

林木及林下土壤N<,2>O排放的研究

N<,2>O是一种重要的温室气体.该研究以中国长白山典型的森林生态系统——阔叶红松林为研究对象，采用空气样品同步采样法和封闭罩法首次对几种主要树木——水曲柳、红松、赤杨（阳生树木）和椴树（阴生树木）的N<,2>O释放进行了较为系统的研究，同时对林下土壤N<,2>O排放进行了实验室模拟实验.获得以下主要研究结果：1.首次确证在自然状态下，林木是森林生态系统中除土壤外的另一重要N<,2>O排放源.2.首次发现光照对阴生树木与阳生树木N<,2>O释放的调节作用不同.3.首次在野外自然条件下，对林木的N<,2>O排放通量进行了测定，并估算了其年排放总量.4.发现在一定条件下，土壤N<,2>O排放和CH<,4>吸收与土壤pH和温度呈正相关.

Transfer ionization of helium in collisions with Cq+ and Oq+ (q=1-3)

Cross-section ratios sigma(TI)/sigma(SC) of transfer ionization (TI) to single capture (SC) of Cq+- and Oq+-He (q = 1 - 3) collisions in the energy range of 15-440 keV/u (0.8-4.2 v(Bohr)) are experimentally determined. It is shown that sigma(TI)/sigma(SC) strongly depends on the projectile velocity, and there is a maximum for E(keV/u)/q(1/2) approximate to 150. Combining the Bohr-Lindhard model and the statistical model, a theoretical estimate is presented, in reasonable agreement with the experimental data when E(keV/u)/q(1/2) > 35.

Ab initio calculations of differential cross sections for single charge transfer in He-3(2+)+He-4 collisions

The single charge transfer process in He-3(2+)+He-4 collisions is investigated using the quantum-mechanical molecular-orbital close-coupling method, in which the adiabatic potentials and radial couplings are calculated by using the ab initio multireference single- and double-excitation configuration interaction methods. The differential cross sections for the single charge transfer are presented at the laboratorial energies E = 6 keV and 10 keV for the projectile He-3(2+). Comparison with the existing data shows that the present results are better in agreement with the experimental measurements than other calculations in the dominant small angle scattering, which is attributed to the accurate calculations of the adiabatic potentials and the radial couplings.

不同降水量处理时5种蒿属植物瘦果粘液溶出

用粘沙法对科尔沁沙地西部5种蒿属植物冷蒿(Artemisiafrigida)、差巴嘎蒿(A.halodendron)、大籽蒿(A.sieversiana)、黄蒿(A.scoparia)、乌丹蒿(A.wudanica)进行了瘦果粘液溶出及粘沙量的比较。主要模拟埋深5mm、降水量为1、2、4、8mm时瘦果的粘液溶出。5种供试植物均有粘液瘦果。在降水量1mm时,供试植物的粘液瘦果就能溶出粘液。当降水量达到2～4mm时,典型的沙生植物乌丹蒿和差巴嘎蒿的粘液瘦果粘沙量平均值分别达到7.31～13.56mg、0.63～2.55mg。除冷蒿外,其它4种植物均有随降水增多、粘液溶出量加大的趋势。粘液瘦果比例从大到小的排序是冷蒿>乌丹蒿>差巴嘎蒿>大籽蒿>黄蒿。在各种处理时,粘沙瘦果百粒瘦果粘沙量由大到小的顺序是乌丹蒿>差巴嘎蒿>大籽蒿>冷蒿>黄蒿。溶出粘液粘沙后,冷蒿瘦果所形成沙团重量达到瘦果重量的5～7倍,差巴嘎蒿2～9倍,大籽蒿3～5倍,黄蒿5～8倍,乌丹蒿5～29倍。流沙先锋植物乌丹蒿和差巴嘎蒿百粒瘦果粘沙量较其它植物大、在较低降水量时这两种植物粘液瘦果粘沙量较大表明瘦果溶出粘液粘沙是植物针对沙地流动性的进化适应之一。

Microstructures and mechanical properties of as-cast Mg–5Al–0.4Mn–xNd (x=0, 1, 2 and 4) alloys

Mg-5Al-0.4Mn-xNd (x=0, 1, 2 and 4wt.%) alloys were prepared by metal mould casting method. The microstructures and mechanical properties were investigated. The results demonstrated that Al11Nd3 phase was formed and mainly aggregated along the grain boundaries with the addition of Nd. Meanwhile, the grain sizes were greatly reduced with the increasing Nd content.

Highly efficient red electroluminescent polymers with dopant/host system and molecular dispersion feature: polyfluorene as the host and 2,1,3-benzothiadiazole derivatives as the red dopant

By selecting polyfluorene as the polymer host, choosing 2,1,3-benzothiadiazole derivative moieties as the red dopant units and covalently attaching 0.3 mol% of the dopant units to the side chain of the polymer host, we developed a novel series of red electroluminescent polymers of dopant/host system with molecular dispersion feature. Their EL spectra exhibited predominant red emission from the dopant units because of the energy transfer and charge trapping from the polymer backbone to the dopant units. The emission wavelength of the polymers could be tuned by modifying the chemical structures of the dopant units.

Room-temperature synthesis and luminescence properties of Eu3+/Tb3+-doped La(1,3,5-BTC)(H2O)(6)

The facile, rapid, and effective synthesis of coordination polymer La(1,3,5-BTC)(H2O)(6) has been realized via direct precipitation at room temperature. It is found that the crystal structure is of monoclinic, space group Cc. The doped Eu3+ or Tb3+ ions samples have the same phase and exhibit red and green emissions under UV light excitation, respectively.