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991.
Isidro S. Marcos Rosalina F. Moro Isabel Costales Miguel A. Escola Pilar Basabe David Díez Julio G. Urones 《Tetrahedron》2009,65(49):10235-1011
A new cyclisation of 3-(but-3-enyl) indole derivatives that produces policyclic compounds with a hexahydrocarbazole structure is described. In this reaction three stereogenic centres are generated in one step, and this process can be considered as evidence of the biogenetic relationship between anominine and tubingensin A. 相似文献
992.
The total synthesis of emericellamides A and B is reported. A convergent, flexible strategy employing peptide chemistry, asymmetric alkylations, and culminating in macrolactamization is described. The previously reported structure of both compounds is confirmed. 相似文献
993.
Two new triterpenoids, schisanbilactones A and B ( 1 and 2 , resp.), and a new natural product, 1‐chloro‐3‐phenylhex‐5‐en‐3‐ol ( 3 ), as well as a known triterpenoid, kadsulactone A ( 4 ), were isolated from the stems of Schisandra bicolor. The structures of the new compounds were elucidated by spectroscopic analyses, including 2D‐NMR techniques. 相似文献
994.
Ya‐Ching Shen Pei‐Show Shih Yun‐Sheng Lin Yu‐Chi Lin Yao‐Haur Kuo Yuh‐Chi Kuo Ashraf Taha Khalil 《Helvetica chimica acta》2009,92(10):2101-2110
Chemical investigation of the sponge Ircinia formosana resulted in the isolation of seven new linear C22‐sesterterpenoids, irciformonins E–K ( 1 – 7 ) in addition to irciformonin A ( 8 ), a previously isolated furanosesterterpenoid (=a furan‐moiety‐containing sesterterpenoid) from the same species. The structures were determined by interpretation of HR‐ESI‐MS and 2D‐NMR spectra. The structure of irciformonin A ( 8 ) was revised. Compound 5 exhibited significant inhibition of peripheral blood mononuclear cell proliferation induced by phytohemaglutinin. 相似文献
995.
Yusuke Imai Atsushi Terahara Keitaro Matsui Nobuhiko Ueno 《European Polymer Journal》2009,45(3):630-3519
Transparent organic-inorganic nanocomposites were successfully synthesized from sulfonic acid-modified poly(bisphenol A carbonate) (SPC) and TiO2 or ZrO2 nanoparticles. The dispersibility of nanoparticles was significantly improved by both the surface treatment of nanoparticles with phosphoric acid 2-ethylhexyl esters (PAEH) and the introduction of a sulfonic acid moiety into the PC chain. It was found that in some cases, crystallization of the matrix caused a reduction in transparency. Efficient dispersion of nanoparticles and the absence of crystallization resulted in highly transparent nanocomposites with up to 42 wt% TiO2 and 50 wt% ZrO2 nanoparticles. The refractive indices of the nanocomposites based on SPC increased with the increasing amount of nanoparticles. Theoretical equation based on Maxwell-Garnett effective medium theory provided reasonably close estimation of the refractive indices to the experimentally observed values. The prepared nanocomposites had lower thermal stability than the host matrix polymers. 相似文献
996.
Canping Jiang Jing Liu Michael Rubacha Abhinav A. Shukla 《Journal of chromatography. A》2009,1216(31):5849-5855
A mechanistic study into Protein A chromatographic resin lifetime limitations is presented. Binding and mass transport properties of two widely used agarose-based Protein A resins were studied to distinguish between the roles of resin fouling due to product/impurity build-up and ligand degradation as contributory factors towards the decline in binding capacity with use. Cycling studies were conducted with and without product loading on the columns to separate out the influence of resin fouling. Ligand degradation under the mildly alkaline conditions used for column regeneration was determined to be the primary cause for Protein A resin capacity decline with usage. The use of lower concentrations of caustic and the use of stabilizing excipients to protect the Protein A ligand during cleaning and sanitization were found to be useful techniques in maintaining column performance. The results presented in this paper provide a clearer understanding of the causative factors that limit Protein A chromatographic resin lifetime. It is anticipated that these findings will assist in the development of more robust and economical downstream manufacturing processes for monoclonal antibody and Fc fusion protein purification. 相似文献
997.
Julita K. Grzeskowiak Anne Tscheliessnig Poh Choo Toh Janet Chusainow Yih Yean Lee Niki Wong Alois Jungbauer 《Journal of chromatography. A》2009,1216(24):4902-4912
Although Staphylococcus Protein A (SpA) affinity chromatography is the state of the art capture step for antibody purification, non-affinity methods are more economical. We used two-dimensional fluorescence difference gel electrophoresis (2-D DIGE) to evaluate the purification of a recombinant IgG1 antibody from cultured cells, with two different processes: (1) SpA capture followed by cation-exchange chromatography (CEX); and (2) CEX capture, followed by anion exchanger, then hydrophobic interaction chromatography. Efficiencies were similar in sodium dodecylsulphate polyacrylamide gel electrophoresis and size-exclusion chromatography; however, 2-D DIGE revealed higher efficiency with SpA than with CEX capture. Thus, 2-D DIGE is a valuable tool for downstream process development. 相似文献
998.
Mohammad Rezaee Yadollah Yamini Shahab Shariati Ali Esrafili Mojtaba Shamsipur 《Journal of chromatography. A》2009,1216(9):1511-1514
Dispersive liquid–liquid microextraction (DLLME) coupled with high-performance liquid chromatography (HPLC)-UV detection was applied for the extraction and determination of bisphenol A (BPA) in water samples. An appropriate mixture of acetone (disperser solvent) and chloroform (extraction solvent) was injected rapidly into a water sample containing BPA. After extraction, sedimented phase was analyzed by HPLC-UV. Under the optimum conditions (extractant solvent: 142 μL of chloroform, disperser solvent: 2.0 mL of acetone, and without salt addition), the calibration graph was linear in the range of 0.5–100 μg L−1 with the detection limit of 0.07 μg L−1 for BPA. The relative standard deviation (RSD, n = 5) for the extraction and determination of 100 μg L−1 of BPA in the aqueous samples was 6.0%. The results showed that DLLME is a very simple, rapid, sensitive and efficient analytical method for the determination of trace amount of BPA in water samples and suitable results were obtained. 相似文献
999.
In the biopharmaceutical industry, column chromatography residuals are routinely assessed by the direct measurement of mock eluates. In this study, we evaluated virus and other impurity carryover between protein A cycles and the feasibility of using a total organic carbon (TOC) analyzer to monitor for column impurity leakage as a correlate for actual measured carryover in mock eluates. Commercial process intermediates were used in scaled down studies of two protein A media, ProSep A (Millipore, Bedford, MA, USA) and MabSelect SuRe (GE Healthcare, Uppsala, Sweden). The chromatography system was programmed to run up to 200 normal load/elution cycles with periodic blank cycles to measure protein and phage carryover, and water flush cycles to measure TOC release. Sustained phage carryover was evident in each study. Carryover and TOC release was lowest in the case where cleaning was most stringent (50 mM NaOH/0.5 M Na2SO4 with MabSelect SuRe). The TOC analysis at this time does not appear to be a viable practical means of measuring impurity carryover; direct measurements in mock eluates appears to be more predictive of column performance. 相似文献
1000.
《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2019,36(6):1575-1601
We studied the asymptotic behavior of local solutions for strongly coupled critical elliptic systems near an isolated singularity. For the dimension less than or equal to five we prove that any singular solution is asymptotic to a rotationally symmetric Fowler type solution. This result generalizes the celebrated work due to Caffarelli, Gidas and Spruck [1] who studied asymptotic proprieties to the classic Yamabe equation. In addition, we generalize similar results by Marques [12] for inhomogeneous context, that is, when the metric is not necessarily conformally flat. 相似文献