Ce:BaAlF_5晶体生长及其光谱特性

采用坩埚下降法生长了 Ce:BaAlF_5单晶、X 射线衍射表明其结构为α-BaAlF_5构型,属于正交晶系,晶胞参数为α=5.146(?),b=7.191(?),c=19.647(?)。测定了晶体的反射光谱、吸收光漕、激发光谱和荧光光谱。Ce~(3+)离子在290nm 附近有一个强吸收峰,为4f-5d 能级的跃迁。在292nm 激发下,有306.5nm 和324nm 两个发射峰、即Ce~(3+)的~2D 能级到~2F_5/2和~2F_7/2能级的跃迁发射。晶体在紫外光照射下发紫光和兰白光。在254nm 激发下,除了 Ce_~(3+)的发射峰,还存在351nm和494nm 两个发光峰,前者与 Ce~(3+)的324nm 发射峰部分重叠,后者为对称性较好的宽带峰。这两个发光峰被认为是晶体缺陷产生的色心发光。

(Nd,Ce):YAG晶体的激光性能

本文给出了(Nd,Ce) :YAG 晶体激光性能的实验结果。与优质 Nd:YAG 晶体比较,我们现在得到的双掺晶体的静态脉冲激光效率提高了80%,激光阈值也显著降低,并具有抗紫外特性。双掺晶体激光性能的大幅度提高,说明在 YAG 晶体里 Ce~(3+)是 Nd~(3+)很好的敏化离子。

Bi-Ce二元氧化物催化剂上丙烯氧化脱氢二聚的动力学与反应机理

丙烯在氧化物催化剂上氧化脱氢二聚反应的研究,文献上主要是在Bi-Sn系催化剂上进行的,不同研究者根据各自的结果,对这一步反应提出了两种不同的机理:一种认为是催化剂表面上吸附丙烯间的二聚(Langmuir-Hinshelwood型机)理;另一种认为是气相丙烯与吸附丙烯间的二聚(Eley-Rideal型机理).我们发现Bi-Ce二元氧化物显示出与Bi-

Eu~(2+)和Ce~(3+)激活的BaYF_5荧光性质

本文讨论了BaYF_5中Eu~(2+)和Ce~(3+)的光谱特征及浓度对光谱的影响。Eu~(2+)和Ce~(3+)均表现为d—f跃迁的特征激发和发射。由于Eu~(2+)—Eu~(2+),Ce~(3+)—Ce~(3+)能量迁移的存在,两者猝灭浓度偏低,其猝灭机理为偶极-偶极相互作用。根据BaYF_5基质中Eu~(2+)和Ce~(3+)的能级关系,发现Ce~(3+)对Eu~(2+)的发射具有明显的敏化作用。其机理主要为非辐射多极子作用,但也存在辐射传递。

助熔剂法合成RPO_4(R=La、Ce、Tb)晶体的研究

本文研究了以(NH_4)_2HPO_4-Li_2CO_3-MoO_3(PbF_2)为助熔剂合成 RPO_4(R=La~(3+),Ce~(3+),Tb~(3+))晶体的工艺,测试和分析了晶胞参数和晶体结构。对 CePO_4和 TbPO_4晶体的激发光谱和荧光光谱进行了讨论和分析。

K_5LnLi_2F_(10)(Ln=La,Gd,Y)的合成和Ce~(3+)在其中的发光

在Ar气氛中,采用高温固相反应法合成了K_5LnLi_2F_(10)(Ln=La,Ce,Gd,Y)化合物。X射线衍射图表明:除K_5YLi_2F_(10)外,均具有与K_5NdLi_2F_(10)(KNLF)相同的结构。计算了K_5LnLi_2F_(10)(Ln=La,Ce,Gd)的晶胞参数和晶胞体积,它们随着La~(3+),Ce(3+),Gd~(3+)的离子半径减小而有规律地减小。测定了K_5Ce_?Ln_(1-?)Li_2F_(10)化合物的激发光谱和荧光光谱。发现Ce~(3+)的激发波长和发射波长随着La~(3+),Gd~(3+),Y~(3+)离子的改变几乎不变,并对这种现象进行了讨论。

Purification of R-phycoerythrin from Porphyra haitanensis (Bangiales, Rhodophyta) using expanded-bed absorption

R-phycoerythrin (R-PE) was purified from leafy gametophyte of Porphyra haitanensis T. J. Chang et B. F. Zheng (Bangiales, Rhodophyta) by a simple, scaleable procedure. Initially, phycobiliproteins were extracted by repeated freeze-thaw cycles, resulting in release from the algal cells by osmotic shock. Next, R-PE was recovered by applying the crude extract with a high concentration of (NH4)(2)SO4 salt directly to the expanded-bed columns loaded with phenyl-sepharose. An expanded-bed volume twice the settled-bed volume was maintained; then low (NH4)(2)SO4 concentration was used to develop the column. After two rounds of hydrophobic interaction chromatography (HIC), R-PE was purified by anion-exchange column. The method was also successful with free-living conchocelis of P. haitanensis. The purified R-PE was identified with electrophoresis, and absorption and fluorescence emission spectroscopy. The results were in agreement with those previously reported. The yield with a spectroscopic purity (OD565/OD280) higher than 3.2 (the ratio of A(565)/A(620) <= 0.02) was 1.4 mg . g(-1) of leafy gametophyte of P. haitanensis. For the free-living conchocelis of P. haitanensis extract, R-PE could be purified successfully with only one round of HIC. The yield with a spectroscopic purity (OD565/OD280) higher than 3.2 (the ratio of A(565)/A(620) <= 0.02) was 5.0 mg . g(-1) of free-living conchocelis of P. haitanensis. The method described here is a scaleable technology that allows a large quantity of R-PE to be recovered from the unclarified P. haitanensis crude extract. It is also a high protein recovery technology, reducing both processing costs and times, which enhances the value of this endemic Porphyra of China.

The encysted dormant embryo proteome of Artemia sinica

The possibility of the brine shrimp Artemia to produce dormant embryo (cysts) in diapause is a key feature in its life history. In the present study, we obtained a proteomic reference map for the diapause embryo of Artemia sinica using two-dimensional gel electrophoresis with a pH range of 4-7 and a molecular weight range of 10-100 kDa. Approximately 233 proteins were detected, and 60 of them were analyzed by capillary liquid chromatography tandem mass spectrometry (LC-MS/MS). Of these, 39 spots representing 33 unique proteins were identified, which are categorized into functional groups, including cell defense, cell structure, metabolism, protein synthesis, proteolysis, and other processes. This reference map will contribute toward understanding the state of the diapause embryo and lay the basis and serve as a useful tool for further profound studies in the proteomics of Artemia at different developmental stages and physiological conditions.

Method for large-scale isolation and purification of R-phycoerythrin from red alga Polysiphonia urceolata Grev

R-phycoerythrin was isolated and purified from a red alga, Polysiphonia urceolata Grev, using Streamline column combined with ion-exchange chromatography or hydroxyapatite chromatography. The purity of R-phycoerythrin isolated by Streamline column was up to 1.66 and the yield of R-phycoerythrin could be as high as 0.68 mg/g frozen P. urceolata. All the eluates from Streamline column were divided into two equivalent parts, respectively. One part was pumped into the ion-exchange column loaded with Q-Sepharose and the other was applied to the adsorption column loaded with hydroxyapatite. The purities of R-phycoerythrin purified using these two methods were both up to 3.26, more than 3.2 the commonly accepted criterion. The yield of purified R-phycoerythrin from the ion-exchange chromatography was 0.40 mg/g frozen P. urceolata and that from the hydroxyapatite chromatography could reach 0.34 mg/g frozen P. urceolata. The purified protein had three absorption peaks at 498, 535, and 565 nm and displayed a fluorescence maximum at 580 nm, which was consistent with the typical spectrum of R-phycoerythrin. The purified R-PE was also identified with electrophoresis. Only one single protein band appeared on native-PAGE with silver staining. SDS-PAGE demonstrated the presence of one 20 kDa major subunit, and one low intensity band corresponding to 33 kDa subunit. The results indicate that using the expanded bed adsorption combined with ion-exchange chromatography or hydroxyapatite chromatography, R-phycoerythrin can be purified from frozen P. urceolata on large scale. (c) 2006 Elsevier Inc. All rights reserved.

Effect of ethanol extract of alga Laurencia supplementation on DNA oxidation and alkylation damage in mice

Laurencia terpenoid extract (LET) had been extracted from the red alga Laurencia tristicha. The study is to investigate the effects of LET supplementation on DNA oxidation and alkylation damages in mice. Forty healthy kunming mice weighing between 18g and 25g were randomly assigned into 4 groups, each consisting of ten animals. The mice were orally intubated respectively for 60 days with the designed concentrations of LET (25, 50, 100 mg/kg b.w.) for three exposed groups and salad oil (0.2 ml) for the blank group. Food and water were free for the animals. Mice in the blank and exposed groups were sacrificed after the last treatment and the blood of each animal was quickly taken for further experiments. The spontaneous and oxidized DNA damages of peripheral lymphocytes induced by H2O2 were analysed by SCGE. O-6-Methy-guanine (O-6-MeG) was measured by high performance capillary zone electrophoresis. There was no significantly difference in DNA spontaneous damage on peripheral lymphocytes of all the mice. The oxidative DNA damage in the 50 mg/Kg body weight supplement group are 286AU with the oxidation of 10 mu mol/L H2O2, significantly lower than the blank group 332AU (p<0.05). The contents of O-6-MeG in plasma in the 50mg/kg b.w. and 100mg/kg b.w. supplement group were 1.50 mu mol/L andl.88 mu mol/L, significantly lower than that of the blank group, which was 2.89 mu mol/L(p<0.05). The results from the present study indicated that the LET were rich in terpenoids and safety to be taken orally and it could improve antioxidative and decrease DNA damage effectively.

CE环境下面向产品竞争力设计与经营决策集成系统研究

从提升产品市场竞争力的角度,提出了面向产品竞争力设计和经营决策的理念,建立了有关的结构模型和框架模型。在此基础上,进一步提出了并行工程环境下实现基于产品开发周期的面向产品竞争力设计与经营决策一体化的设想;研究了面向产品竞争力设计与经营决策集成系统的特征、结构和功能。最后以汽车车身为例对并行工程环境下的车身设计与经营决策集成系统进行了应用研究。

碳酸盐岩风化成土过程中REE超常富集及Ce强烈亏损的地球化学机理

碳酸盐岩的REE含量极低，但最近在贵州一些碳酸盐岩风化表土层底部首次发现了REE的超常富集层，REE总量最高可达近31000μg/g;Ce强烈亏损，δCe值最低达0.007。这种低背景、高富集、强分异的REE富集现象在贵州碳酸盐岩风化壳中具有一定的普遍性。选取发育在下三叠统花溪灰岩和平坝白云岩之上的两个较具代表性的碳酸盐岩风化壳进行研究，结果表明，这种富集现象与碳酸盐岩风化成土的两阶段性密切相关。（1）在残积土形成阶段（风化早期），碳酸盐的快速溶解导致风化前缘形成一个垂直方向相对狭窄、突变的碱性障(pH值为8左右）。此障既能有效地将碳酸盐岩分解释放的REE以及下渗水携带的REE分解沉淀和以吸附于粘土矿物上的方式富集，也容易使Ce^3+氧化成Ce^4+，与HCO3^-形成稳定的可溶性络合物随下渗雨水流走，从而使Ce进一步亏损。（2）残积土演化阶段，轻、重稀土发生明显分异，Ce^3+氧化成Ce^4+并发生水解沉淀，致使下渗水富重稀土而贫Ce，最终使REE在剖面上显示出一般风化壳共有的分异特征。另外，根据对碳酸盐岩中的酸不溶物、可溶性稀土的提取以及质量平衡计算，碳酸盐岩能够提供足够的REE物源；以可溶态为主的赋存状态有利于REE的淋滤（活化）。