138 resultados para Ford, Gerald R., 1913-
Resumo:
A new method for the preparation of polyalkyl and polyarenefullerene derivatives C-60(RH)(n)(R=Bu,n=1-3; R=Ph,n=1-10) by the reaction of C-60 with organotin hydride in toluene is described. Another series of products of stannanes R(a)Sn(b)H(c) (R=Bu, a=3-8, b=1-4, c=0-3 R=Ph, a=3-11, b=1-5, c=0-4) were also obtained, which shows that C-60 can catalyze polymerization of organic-tin. These products were determined by mass and infrared spectrometry. And the possible reaction mechanisms are discussed.
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The interaction of [(C(5)H(4)R)(2)NdCl.2LiCl] (R = H, Bu(t)) with one equivalent of Li[(CH2)(CH2)PPh(2)] in refluxing tetrahydrofuran gave the purplish-blue complex [(C(5)H(4)R)(3)NdCH2P(Me)Ph(2)] in 50% yield. The compounds have been fully characterized by analytical, spectroscopic and X-ray diffraction methods. Variable temperature P-31{H-1} NMR spectroscopy indicated the existence of the following equilibrium: [(C(5)H(4)R)(3)NdCH2P(Me)Ph(2)] + THF reversible arrow (C(5)H(4)R)(3)Nd(THF) + CH2=P(Me)Ph(2). At room temperature, the exchange between the coordinated and free ylide ligand is slow on the NMR time scale.
Resumo:
本文用R_2O_3(R=Y,Gd,La),V_2O_6,Nb_2O_5和高温固相反应法合成了复合钒铌酸盐RVMb_2O_3,并以此为基质研究了Eu~(3+)和Dy~(3+)在其中的光谱性质.实验表明,Eu~(3+)在这三个化合物中均处于偏离反演对称中心的格位上,Eu~(3+)的荧光强度的红/横比(R/O)和Dy~(3+)的黄/蓝比(Y/B)均随R~(3+)的电荷半径比的减小而下降.同时还研究了Bi~(3+)和温度对Dy~(3+)的发射强度的影响.
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At room temperature, the Bi3+ ion shows broad band characters of its luminescence in Ca2B2O5, M3B2O6 ( M=Ca,Sr ) and SrB4O7. The maxima of the Bi3+ S-1(0)-->P-3(1) absorption bands are located in the range of 240-300nm, but the energy variation of the corresponding P-3(1)-->S-1(0) emissions is very large. The maxima of these emission bands change from 350nm in Ca3B2O6;Bi3+ to 586nm in SrB4O7:Bi3+. The Stokes shift of the Bi3+ luminescence increases from 6118 cm-1, in Ca2B2O5:Bi3+, to 24439 cm-1, in SrB4O7:Bi3+. The emission intensity of the Bi3+ luminescence increases with the decreasing Stokes shift. It has been found that in Ca2B2O5, the Bi3+ ion could transfer its excitation energy to the R3+ ions ( R=Eu, Dy, Sm, Tb ) , but in, Ca3B2O6 and Sr3B2O6, only Bi3+-->Eu3+ was observed. No energy transfer from Bi3+ to R3+ was detected in SrB4O7.
Resumo:
The novel NS-containing zirconacycle complexes Cp2ZrCl[SC(H)NR] (1a, R = C6H5; 1b, R = 2-C10H7; 1c, R= C-C6H11; 1d; R = n-C4H9) were obtained by insertion reactions of Cp2Zr(H)Cl with RNCS. 1(a-d) could react further with Cp2Zr(H)Cl to yield a sulphur-bridging compleX (Cp2ZrCl)2S (2) and a Schiff base RN=CH2. The crystal structure of la has been determined by X-ray analysis.
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本文报导了Eu~(3+),Dy~(3+)在Ba_2RV_3O_(11)(R=Y,Gd,La)基质中的光谱性质、Bi~(3+)对Dy~(3+)发射强度的影响及温度对Dy~(3+)发射强度的猝灭情况.研究了被取代离子R~(3+)(R=Y,Gd,La)对基质电行迁移带、Eu~(3+)的红橙比、Dy~(3+)黄蓝比的影响,还给出了Dy~(3+)的浓度猝灭值.
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研究了激活离子Eu~(3+),Dy~(3+)和Bi~(3+)在具有相同结构的LaMSb_2O_7(M=Li,Na,K)中的发光特性,得到了发白光的磷光体LaNaSb_2O_7:Dy~(3+)。讨论了化学键的共价程度对Eu~(3+)和Dy~(3+)超灵敏跃迁强度比的影响。发现当用281nm激发试样时,Bi~(3+)对Eu~(3+)具有敏化作用并解释了其原因。
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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。
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This article documents the addition of 512 microsatellite marker loci and nine pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Alcippe morrisonia morrisonia, Bashania fangiana, Bashania fargesii, Chaetodon vagabundus, Colletes floralis, Coluber constrictor flaviventris, Coptotermes gestroi, Crotophaga major, Cyprinella lutrensis, Danaus plexippus, Fagus grandifolia, Falco tinnunculus, Fletcherimyia fletcheri, Hydrilla verticillata, Laterallus jamaicensis coturniculus, Leavenworthia alabamica, Marmosops incanus, Miichthys miiuy, Nasua nasua, Noturus exilis, Odontesthes bonariensis, Quadrula fragosa, Pinctada maxima, Pseudaletia separata, Pseudoperonospora cubensis, Podocarpus elatus, Portunus trituberculatus, Rhagoletis cerasi, Rhinella schneideri, Sarracenia alata, Skeletonema marinoi, Sminthurus viridis, Syngnathus abaster, Uroteuthis (Photololigo) chinensis, Verticillium dahliae, Wasmannia auropunctata, and Zygochlamys patagonica. These loci were cross-tested on the following species: Chaetodon baronessa, Falco columbarius, Falco eleonorae, Falco naumanni, Falco peregrinus, Falco subbuteo, Didelphis aurita, Gracilinanus microtarsus, Marmosops paulensis, Monodelphis Americana, Odontesthes hatcheri, Podocarpus grayi, Podocarpus lawrencei, Podocarpus smithii, Portunus pelagicus, Syngnathus acus, Syngnathus typhle,Uroteuthis (Photololigo) edulis, Uroteuthis (Photololigo) duvauceli and Verticillium albo-atrum. This article also documents the addition of nine sequencing primer pairs and sixteen allele specific primers or probes for Oncorhynchus mykiss and Oncorhynchus tshawytscha; these primers and assays were cross-tested in both species.
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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.
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Phycoerythrins have been widely used in food, cosmetics., immunodiagnostics and analytical reagents. An efficient one-step chromatography method for purification of R-phycoerythrins from Polysiphonia urceolata was described in this paper. Pure R-phycoerythrin was obtained with an absorbance ratio A(565)/A(280) of 5.6 and a high recovery yield of 67-33%, using a DEAE-Sepharose Fast Flow chromatography with a gradient elution of pH, alternative to common gradient elution of ionic strength. The absorption spectrum of R-phycoerythrin was characterized with three absorbance maxima at 565, 539 and 498 mum, respectively and the fluorescence emission spectrum at room temperature was measured to be 580nm. The results of native-PAGE. and SDS-PAGE showed no contamination by other proteins in the phycoerythrin solution. which suggests an efficient method for the separation and purification of R-phycoerythrins from Polysiphonia urceolata. (C) 2004 Elsevier B.V. All rights reserved.
Resumo:
The C-phycocyanin and the R-phycoerythrin were purified from the blue-green alga Spirulina platensis and red alga Polysiphonia urceolata respectively. Both sodium periodate and glutaraldehyde are effective coupling agents being capable of constructing the R-phycoerythrin-C-phycocyanin conjugate, which was also called phycobiliproteins energy transfer model. The two artificial conjugates constructed with different methods were purified by Sephadex G-200 chromatography respectively. Spectra analysis indicated that energy transfer occurred in the two conjugates. The conjugate with sodium periodate had the higher efficiency of energy transfer than that with glutaraldehyde conjugate.
Resumo:
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.
Resumo:
The mouse tumor cell 5180 and human liver carcinoma cell SMC 7721 cells were first treated with R-PE and its subunits (alpha, beta, gamma subunits), then irradiated with Argon laser (496 nm, 28.8 J/cm(2)). Survival rate was measured by MTT method. In order to compare the phototoxicity in normal cells, the mouse marrow cells were treated with photofrin II and beta-subunit, irradiated with 45 J/cm(2) of light; survival rate was also measured by MTT method. The result showed that R-PE subunits had better PDT effect on s180 cells than R-PE and lower phototoxicity in marrow cells than photofrin II Flow cytometric analysis showed that PDT results in a growth inhibition and a G(0)-G(1) cell cycle arrest in SMC 7721 cells. The tumor cells inhibited by PDT in vivo were morphologically observed by TEM, the tumor cell death was daze to the occlusion of tumor blood vessels and inducement of cell programmed death in nuclei. Therefore, with the advantage in special fluorescence activity, loth molecular weight, good light absorbent character and weak phototoxicity, R-PE subunit is art attractive option for improving the selectivity of PDT.
Resumo:
R-phycoerythrin, a light-harvesting protein in some marine algae, and can be widely used in medicine, was isolated and purified from a red alga, Palmaria palmata (Lannaeus) Kuntze, using the streamline column (expanded bed adsorption) combined with ion-exchange chromatography. Because the crude extract was applied to the column upwardly, the column would not be blocked by polysaccharides usually very abundant in the extract of marine alga, this kind of blockage could hardly lie overcome in ordinary chromatographic column. After applying the crude extract containing 0.5 mol/L (NH4)(2)SO4, (NH4)(2)SO4 solution of different concentrations (0.2 mol/L, 0.1 mol/L and 0.05 mol/L) was used to elute the column downwardly and the eluates were collected and desalted. The desalted eluates were then applied onto all ion-exchange chromatographic column loaded with Q-sepharose for further purification of the R-phycoerythrin. Through these two steps, the purity (OD565/OD280) of the R-phycoerythrin from P. palmata was up to 3.5, more than 3.2, the commonly accepted criterion for purity, and the yield of the purified R-phycoerythrin could reach 0.122 mg/g of frozen P. palmata, much higher than that of phycobiliproteins purified with the previous methods. The result indicated that the cost of R-phycoerythrin will drop down with the method reported in this article.