RE_(1-x)B_xF_(3-y)(RE=Y、La、Ce、Gd;B=Ca、Ba)的敏感性质的研究

LaF_3作为离子选择性电极和对气体的敏感性质已进行了一定的研究,但其他稀土氟化物的敏感性质却未见报道。本文合成了RE_(1-x)B_xF_(3-y),研究了它们的结构、电学性质及敏感性质,得到有可能在150℃使用的固体电解质氧敏材料。 (一) RE_(1-x)B_xF_(3-y)的结构分析 结构分析表明,Ca、Ba置换RE的含量少时,如La_(0.95)Ba_(0.05)F_(3-y)、Ce_(0.95)Ca_(0.05)F_(3-y)的X射线衍射分析结果与LaF_3、CeF_3相似,说明它们是固溶体。而Ca置换RE含量较多时,如Y_(0.71)Ca_(0.29)F_(3-y)、Gd_(0.85)Ca_(0.15)F_(3-主)的X射线衍射分析结果却与相应的YF_3和GdF_3完全不

碱性染料杂多酸多元配合物显色反应的研究——Ⅵ.丁基罗丹明B-砷钼杂多酸-聚乙烯醇-124体系

本文研究了丁基罗丹明B-砷钼杂多酸-PVA-124体系,由于形成高取代氢原子的杂多酸而使反应灵敏度大增,ε值高达6.9×10~5 L·mol~(-1)·cm~(-1)。缔合物的组成比As(V):BRB=1:7。红外光谱研究证明,染料和杂多酸形成了离子对缔合物。本法可成功地用于水样和试剂中痕量砷的测定。测定下限分别为2.0ppb(水样)和2×10~(-6)％(试剂)。

超高灵敏显色反应及其应用的研究——Ⅴ.钨(Ⅴ)-SCN~--乙基罗丹明B-PVA-124体系

本文研究了在聚乙烯醇-124存在下,钨(V)-SCN~--乙基罗丹明B超高灵敏显色体系。缔合物λ_(max)=585nm,表观摩尔吸光系数ε_(585)=1.9×10~6L·mol~(-1)·cm~(-1)。钨浓度在0.1～1.5μg/25ml范围内符合比尔定律,方法曾用于水样及钢样中痕量钨的测定,结果较满意。

超高灵敏显色反应及其应用的研究Ⅲ.锑(Ⅲ)—乙基罗丹明B—碘化物体系

本文研究了在聚乙烯醇-124存在下,锑(Ⅲ)—乙基罗丹明B—碘化物的显色反应。缔合物λ_(max)=605nm表观摩尔吸光系数为7.0×10~3。锑浓度在0.1～2.5μg/25ml时服从比尔定律。藉氢化物分离技术,本法可用于地球化学标样中痕量锑的测定。

Nd-Fe-B-Si合金的研究

为了探索提高Nd-Fe-B磁性材料的居里温度T_C,我们采用了与文献不同的组成和制 条件,研究了Si对合金的物相、T_C等的影响,得出Nd-Fe-B-Si是一种有希望的非钴高居里温度合金体系. 试样系以钕铁、硅铁、硼铁和还原铁粉为原料,按 Nd_(15)Fe_(77-x)Si_xB_8(x=4、8、16、18 at％)配比,在石墨电阻炉内于Ar气保护下熔炼而成.T-σ曲线在日本MB-2型磁天平上测得;微区分析和x-射线衍射分别用JXA-840扫描电镜和日本理学2028x-射线衍射仪进行.

碱性染料杂多酸多元配合物显色反应的研究 Ⅴ.乙基罗丹明B-磷钼杂多酸-聚乙烯醇体系

本文研究了乙基罗丹明B-磷钼杂多酸-聚乙烯醇(PVA)显色体系,提出了高灵敏度的测磷分光光度法。缔合物最大吸收λ_(max)=584nm。表观摩尔吸光系数ε_(586)为3.2×10~5L·mol~(-1)·cm~(-1)。提高介质酸度和添加还原剂可消除SiO_3~(2-)、AsO_4~(3-)等的干扰。缔合物中P(V):ERB~+=1:4。红外光谱研究证明,染料阳离子与杂多酸阴离子形成了离子对缔合物。本法可用于钢样及试剂中磷的测定,测定下限达1×10~(-5)％(1g试样)。

超高灵敏显色反应及其应用的研究——镉-乙基罗丹明B-碘化物体系

本文介绍了镉-乙基罗丹明B-碘化物超高灵敏显色体系,确定了分光光度测定痕量镉的条件,时反应机理作了初步讨论。方法的灵敏度很高,表观摩尔吸光系数可达1.3×10~6。拟定了直接测定水样和硫酸锌试剂中镉的方法,检测下限分别为0.5ppb和1×10~(-5)％。

超高灵敏显色反应及其应用的研究 Ⅱ.汞(Ⅱ)-乙基罗丹明 B-碘化物体系

本文研究了在聚乙烯醇-124存在下,汞(Ⅱ)-乙基罗丹明B_碘化物超高灵敏显色体系及其反应机理。缔合物λ_(max)=605nm,表观摩尔吸光系数ε_(605nm)=1.14×10~6L.mol~(-1).cm~(-1)。汞(Ⅱ)浓度在0—2.5μg/25ml时符合比耳定律。方法可用于水样及地球化学标样中痕量汞的测定。

若丹明6G/二甲苯红B混合染料体系的研究

测量了R6G/二甲苯红B二元混合染料体系的荧光光谱、荧光寿命和激光输出性能。表明它可作激光工作物质。定量地计算了R6G/二甲苯红B分子间的能量转移效率E、能量转移速率常数R_(et)及临界距离R_0,研究了分子间能量转移的过程和主要机制。

Laurendecumallenes A-B and laurendecumenynes A-B, halogenated nonterpenoid C-15-Acetogenins from the marine red alga Laurencia decumbens

Four new halogenated nonterpenoid C-15-acetogenins, 4:7,6:13-bisepoxy-9,10-diol-1,12-dibromopentadeca-1,2-diene (1, laurendecumallene A), 4:7,6:12-bisepoxy-9,10-diol-1,13-dibromopentadeca-1,2-diene (2, laurendecumallene 13), (3Z)-6:10,7:13-bisepoxy-12-bromo-9-hydroperoxylpentadeca-3-en-1-yne (3, laurendecumenyne A), and (3Z)-6:10,9:13-bisepoxy-12-bromo-7-chloropentadeca-3-en-1-yne (4, laurendecumenyne 13), together with one known halogenated C-15-acetogenin elatenyne (5) were isolated and identified from the organic extract of the marine red alga Laurencia decumbens. Their structures and relative stereochemistry were established by means of spectroscopic analysis including UV, IR, high-resolution electrospray ionization mass spectrometry (HRESIMS), and ID and 2D NMR techniques. All these metabolites were submitted for the cytotoxic assay against tumor cell line A549 (human lung adenocarcinoma), but all of them were found inactive (IC50 > 10 mu g/mL).

Chinikomycins A and B: Isolation, structure elucidation, and biological activity of novel antibiotics from a marine Streptomyces sp isolate M045

In our screening of marine Streptomycetes for bioactive principles, two novel antitumor antibiotics designated as chinikomycins A (2a) and B (2b) were isolated together with manumycin A (1), and their structures were elucidated by a detailed interpretation of their spectra. Chinikomycins A (2a) and B (2b) are chlorine-containing aromatized manumycin derivatives of the type 64-pABA-2 with an unusual para orientation of the side chains. They exhibited antitumor activity against different human cancer cell lines, but were inactive in antiviral, antimicrobial, and phytotoxicity tests.

Characterization of the main light-harvesting chlorophyll a/b-protein complex of green alga, Bryopsis corticulans

The main light-harvesting chlorophyll a/b -protein complex (LHC II) has been isolated directly from thylakoid membranes of shiphonous green alga, Bryopsis corticulans Setch. by using two consecutive runs of anion exchange and gel-filtration chromatography. Monomeric and trimeric subcomplexes of LHC 11 were obtained by using sucrose gradient ultracentrifugation. Pigment analysis by reversed-phase high performance liquid chromatography showed that chlorophyll a (Chl a), chlorophyll b (Chl b), neoxanthin, violaxanthin and siphonaxanthin were involved in LHC 11 from B. corticulans. The properties of electronic transition of monomeric LHC II showed similarities to those of trimeric LHC II. Circular dichroism spectroscopy showed that strong intramolecular interaction of excitonic dipoles between Chl a and between Chl b exist in one LHC II apoprotein, while the intermolecular interaction of these dipoles can be intensified in the trimeric structure. The monomer has high efficient energy transfer from Chl b and siphonaxanthin to Chl a similarly to that of the trimer. Our results suggest that in B. corticulans, LHC II monomer has high ordered pigment organization that play effective physiological function as the trimer, and thus it might be also a functional organization existing in thylakoid membrane of B. corticulans.

Isolation of the main light-harvesting chlorophyll a/b-protein complex from thylakoid membranes of marine alga, Bryopsis corticulans by a direct method

The main chlorophyll a/b light-harvesting complex (LHC 11) has been isolated directly from thylakoid membranes of marine green alga (Bryopsis corticulans Setch.) by two consecutive runs of anion exchange and gel-filtration chromatography. LHC 11 proteins in the membrane extracts treated with 3% n-Octyl-b-D-glucopyranoside (OG) obtained specific binding ability on Q Sepharose column, and thus were isolated from the thylakoid membranes in a highly selective fraction. The monomeric, trimeric and oligomeric subcomplexes of LHC 11 have been obtained by fractionation of the LHC 11 mixes with sucrose density gradient ultracentrifugation. The SDS-PAGE analysis of peptide composition and absorption spectrum showed that LHC 11 monomers, trimers and oligomers prepared through this work were intact and in high purity. Our report is the first to show that it is possible to purify LHC If directly from thylakoid membranes without extensively biochemical purification.

Characterization of the artificially covalent conjugate of B-phycoerythrin and R-phycocyanin and the phycobilisome from Porphyridium cruentum

B-phycoerythrin (BPE) and R-phycocyanin (RPC) were purified from Porphyridium cruentum by Sephadex G-200 chromatography, then the BPE was attached covalently to the RPC by reacting their amino groups to form the artificially covalent BPE-RPC conjugate in which the excitation energy can transfer from the BPE to the RPC with low efficiency. Meanwhile, the intact phycobilisome (PBS) consisting of BPE, RPC, APC and L-CM was isolated and purified from Porphyridium cruentum, and the purified PBS was found to keep intact if the solution contains sucrose. Comparison of spectroscopic properties between the purified PBS and the BPE-RPC conjugate suggests that the BPE-RPC conjugate is much more stable than the purified PBS. The construction of BPE-RPC conjugate with low efficiency of the excitation energy transfer may be useful for preparing phycobiliprotein probes. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.