Study on Luminescence Properties of High-Density Phosphors BiTaO4∶Pr3+ and BiTaO4

The photoluminescence properties of BiTaO4∶Pr3+ and BiTaO4 at room temperature were studied, and the infrared transmission and diffusion reflection spectra of BiTaO4 were measured. The photoluminescence spectrum of BiTaO4 peaks at about 420, 440 and 465 nm. There has an obvious excitation band from 330 to 370 nm. The photoluminescence spectrum of BiTaO4∶Pr3+ consists of the characteristic emission of Pr3+, and its main peak is at 606 nm from 3P0→3H6 transition of Pr3+. Its excitation spectrum consists of the wide band with maximum at 325 nm, the wide band in the range of 375～430 nm, and the characteristic excitation of Pr3+. The bands at 325 nm and 375～430 nm may be from the absorption of the charge transfer transition of the tantalate group and defect energy levels in its forbidden band, respectively. There is energy transfer from host to Pr3+. Because both the host density and photoluminescence peak intensity of BiTaO4∶Pr3+ are superior to PbWO4, BiTaO4∶Pr3+ may be a potential heavy scintillator.     

A comparison of three approaches for predicting C4 species cover of northern mixed grass prairie

The C4 composition of Canadian mixed-grass communities is more sensitive to environmental change than other grasslands. Reliable methods of detecting such changes are necessary if these landscapes are to be properly managed. One approach is to use satellite remote sensing systems. Various studies have shown that the asynchronous seasonality of C3 and C4 species allows the relative abundance of each photosynthetic type to be estimated using temporal trajectory indices (TTIs) of sensor-derived normalized difference vegetation index (NDVI). In this study, we compared three approaches for predicting C4 species cover at Grasslands National Park (GNP) (Saskatchewan, Canada). TTIs related to Approach I were calculated from plots of NDVI vs. day-of-year (DOY). TTIs related to Approach II were calculated from plots of normalized cumulative NDVI vs. growing degree day (GDD). TTIs related to Approach III were calculated as ratios of early-season NDVI to late-season NDVI. Our analyses were conducted at two separate ecological scales. A within-community analysis used field-sampled data from upland grassland to compare techniques at sampling resolutions of 0.5, 2.5, 10, and 50 m. An across-community analysis compared techniques using a vegetation survey of the GNP region and TTIs calculated from Advanced Very High Resolution Radiometer (AVHRR) data (1 km). At both scales, TTIs related to the timing of specific phenological events were the best predictors of C4 species cover. While all techniques performed well in the within-community study, Approach III performed best. Here, the predictive ability of each approach was weak at a resolution of 0.5 m but stronger at 2.5, 10, and 50 m resolutions. We also found that the optimal sampling dates for Approach III fell within a certain GDD range. This is encouraging for the a priori selection of sample dates, which would make the need for full seasonal time series redundant. In the across-community analysis, the AVHRR-derived Approach II TTIs were better able to discriminate among grasslands of different C4 composition than any other technique (overall accuracy=74%). However, for some C4 cover classes, the predictive accuracy of this approach was low. While these results are encouraging for the use of spectral data in monitoring the C4 cover of northern prairie, various research issues remain. At the within-community level, these include (a) further attempts to define objective criteria for the a priori identification of sampling dates for Approach III, and (b) and the extension of such studies to other growing seasons and community types/grassland regions. At the across-community level, these include the expansion of such techniques to a larger geographical region that contains a wider range in C4 cover values and land use types (e.g. ungrazed vs. grazed grasslands).     

基于PNX1300系列多媒体处理器的MPEG-4视频压缩卡设计

介绍了一种基于MPEG—4视频压缩标准和PNX1300系列多媒体处理器的MPEG—4视频压缩卡的设计方案，给出了该视频压缩卡的硬件结构框图，详细分析了其软件编码器的设计流程。     

IPv6过渡机制讨论

本文在简要地介绍Ngtrans工作组提出的大多数过渡机制的基础上，尝试对它们进行区分、分类，并对每一种过渡机制的优缺点进行分析。另外．还对这些机制的布置以及一部分支持这些机制的产品平台进行讨论。     

Potential tissue implants from the networks based on 1,5-dioxepan-2-one and ε-caprolactone

The synthesis and characterization of degradable polymeric networks for biomedical applications was performed. Cross-linked films of poly(ε-caprolactone) (PCL) and poly(1,5-dioxepan-2-one) (PDXO) having various mole fractions of monomers and different cross-link densities were successfully prepared using 2,2′-bis-(ε-caprolactone-4-yl) propane (BCP) as cross-linking agent. Reaction parameters were carefully examined to optimise the film-forming conditions. Networks obtained were elastomeric materials, easy to cast and remove from the mould. Effect of CL content and cross-link density on the final properties of the polymer network was evaluated. High CL content or degree of cross-linking led to increase in Young's modulus and decrease in elongation at break. An increase in crystalline domains in films having a higher CL content was observed by optical microscopy. A greater thermal stability was observed in films having a high CL content. The hydrophilicity of the materials could be tailored by changing the CL content. The surface of the films became rougher with higher CL content.     

Amtshaftung bei Bauführung im Hochwassergebiet; fehlerhafter Flächenwidmungsplan; Nachforschungspflichten der Gemeinde

Bestehen ausreichende Anhaltspunkte für die Hochwassergef?hrdung, ist die Gemeinde verpflichtet, sich durch Nachforschungen Gewissheit über das Vorliegen oder Nichtvorliegen eines Hochwasserabflussgebietes gem § 38 Abs 3 WRG zu verschaffen. Liegt ein solches vor, hat sie gem § 12 Abs 1 Z 2 krnt GplG dieses im Fl?chenwidmungsplan ersichtlich zu machen. Erteilt die Gemeinde eine Baubewilligung ohne diese von der Erteilung einer wasserrechtlichen Bewilligung abh?ngig zu machen, haftet sie für die Kosten der Bauführung, die bei gesetzes-konformer Vorgangsweise unterlassen worden w?re.     

介孔氧化铁对正辛醇乙氧基化反应的催化性能

以十二烷基磺酸钠为模板剂、乙二胺为碱性介质,将水热法合成的氧化铁/十二烷基磺酸钠复合中孔材料在550℃、空气气氛中煅烧10h,除去模板剂,得到介孔氧化铁。通过X射线衍射、氮气吸附-脱附方法对介孔氧化铁的晶体结构和表面物性进行表征。表征结果显示,煅烧后的介孔氧化铁具有典型的六方介孔的结构特征,平均孔径为5.4nm。将介孔氧化铁用于催化正辛醇乙氧基化反应,研究结果表明,升高反应温度和初始压力、增加催化剂用量,可加快环氧乙烷的反应速率,同时产物的相对分子质量分布较窄。当平均聚合度为6.5时,正辛醇聚氧乙烯醚相对分子质量分布的选择性系数达到21.1。     

Übergangene Nachbarn; Erlangung der Parteistellung; Sachlichkeitsgebot

Die Regelung über die Erlangung der Parteistellung übergangener Nachbarn durch Geltendmachung von Einwendungen bis l?ngstens drei Monate nach dem angezeigten Baubeginn ist wegen der Anknüpfung an einen untauglichen Zeitpunkt verfassungswidrig.     

单微乳液中制备Ag/TS-1及丙烯气相环氧化

采用N2H4还原含AgNO3的单微乳液制备了Ag／TS-1催化剂。TEM表征结果表明，Ag高度分散于TS-1之上。以H2、O2存在下的丙烯气相环氧化为探针反应，考察了Ag／TS-1的催化性能。结果表明，采用Ag／TS-1为催化剂，Ag的负载量为1％（质量分数，下同），823 K焙烧后，373 K下反应30 min时，丙烯转化率为1．69％，环氧丙烷（Propylene oxide，PO）选择性为93．2％。当Ag的负载量超过2％时，反应过程中生成大量的热，造成PO的选择性下降。采用Ag的负载量为8％的Ag／TS-1催化剂，消除热效应后，丙烯的转化率为2．46％．PO的选择性为79．2％。     

VSC8150在波分复用系统开销提取中的应用

波分复用系统将不同波长的光复用在一起进行传输,以满足对传输容量和传输距离的各种需求。介绍了一种开销监视与提取的设计方法,使用VSC8150提取承载在波分复用系统相应波长上SDH信号的开销。分析了VSC8150的工作原理,管脚和外部接口,以及与FPGA、单片机共同完成B1重新计算,开销提取,B1,J0提取。此外,还提出将帧丢失,帧失步等错误状态传送给单片机和网管的方法。本设计增强了波分复用系统网管管理参数,功能和灵活性,这会在系统维护时带来较大的方便。该设计已经成熟应用在实际的波分复用系统中。