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We probe the universality of acceleration scale a0 in Milgrom's modified Newtonian dynamics(MOND)using the recently released rotation curve data from SPARC galaxies.We divide the SPARC data into different subsamples according to the morphological types of galaxies,and fit the rotation curve data of each subsample with the theoretical prediction of MOND.MOND involves an arbitrary interpolation function which connects the Newtonian region and the MOND region.Here we consider five different interpolation functions that are widely discussed in the literature.It is shown that the best-fitting a0 significantly depends on the interpolation functions.For a specific interpolation function, a0 also depends on the morphological types of galaxies,implying that a0 may be not a universal constant.Introducing a dipole correction to a0 can significantly improve the fits.The dipole directions for four of the five interpolation functions point towards an approximately consistent direction,but a0 still varies for different interpolation functions. 相似文献
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Shi-Hao Peng Xiu-Yun Yue Ya-Li Wang Qi Wei Su-Ping Cui Zuo-Ren Nie Qun-Yan Li 《Chromatographia》2018,81(2):247-256
Ethyl-bridged organic–inorganic hybrid silica particles were prepared via a sol–gel and hydrothermal synthesis approach using 1,2-bis(triethoxysilyl)ethane (BTESE) as the sole precursor, and triblock copolymer poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (P123) and dodecyltrimethylammonium bromide (DTAB) as combined templates. The morphology, pore structure, chemical composition and liquid chromatographic performance of the obtained materials were investigated in detail. The particles exhibit a high surface area of 1136.40 m2/g, together with a pore volume of 0.39 cm3/g and an average pore size of 2.30 nm. Used as stationary phase for high-performance liquid chromatography (HPLC), the particles without extra bonding either C18 or C8 can successfully separate a mixture of uracil, phenol, pyridine, methylbenzene, ethylbenzene and tert-butylbenzene. The obtained materials also show practical application in the separation of phthalate acid esters (PAEs), which are harmful to environment and human health. Although the columns packed with ethyl-bridged organic–inorganic hybrid silica show lower column efficiency and peak symmetry compared to commercial column, they have considerably higher chemical stability in alkaline mobile phase. The HSS column also possesses high mechanical stability which is similar to that of the commercial column. 相似文献
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Su-Ping He Gui-Yu Tan Gang Li Wei-Ming Tan Tie-Gui Nan Bao-Min Wang Zhao-Hu Li Qing X. Li 《Analytical and bioanalytical chemistry》2009,393(4):1297-1303
Artemisinin is an endoperoxide sesquiterpene lactone isolated from the Chinese medicinal plant Artemisia annua L. It has been widely used in South-East Asia and Africa as an effective drug against sensitive and multidrug-resistant Plasmodium falciparum malaria. A monoclonal antibody (mAb), designated as 3H2, was generated with artesunate–bovine serum albumin conjugate as
the immunogen. mAb 3H2 was used to develop a highly sensitive and specific indirect competitive enzyme-linked immunosorbent
assay (icELISA) for artemisinin. The concentration of analyte producing 50% of inhibition (IC50) and the working range of the icELISA were 1.3 and 0.2–5.8 ng/mL, respectively. The mAb 3H2 recognized the artemisinin analogs
artesunate, dihydroartemisinin, and artemether with cross-reactivity of 650%, 57%, and 3%, respectively, but negligibly recognized
deoxyartemisinin and the artemisinin precursors arteannuin B and artemisinic acid. The average recoveries of artemisinin fortified
in A. annua samples at concentrations from 156 to 5,000 μg/g determined by icELISA ranged from 91% to 98%. The icELISA was applied for
the determination of artemisinin in different wild A. annua samples and the results were confirmed by high-performance liquid chromatography (HPLC) analysis. The correlation coefficient
(R
2) between the two assays was larger than 0.99, demonstrating a good agreement between the icELISA and HPLC results. This ELISA
is suitable for quality assurance of A. annua L. materials.
Figure
Artemisia annua plant and antimalarial drugs derived from artemisinin 相似文献
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IntroductionCriticalmicelleconcentration (cmc)ofsurfactantsinaqueoussolutionisoneofthemostusefulparametersforcharacterizingthepropertiesofsurfactants.Overaverynarrowconcentrationrangearoundthecmctransitionsoftheexistenceofsurfactantsoccurfrommonomer ,premicel lartomicellar .Andcompanyingthesetransitions ,manyotherimportantpropertiesofsurfactantsolution ,suchassurfacetension ,interfacialtension ,conductivity ,osmoticpressure ,detergency ,emulsification ,foamingandsoon ,alsochangesharplyatthepoi… 相似文献
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电磁感应加热与原子荧光光谱联用测定海产品中的无机汞和有机汞 总被引:1,自引:2,他引:1
研制了电磁感应加热装置和磁感应加热柱,并将其应用于有机汞的在线氧化。与冷蒸汽发生-原子荧光光谱法联用,在线测定了海产品中的无机汞和有机汞。样品溶液与K2S2O8在线混合后流经磁感应加热柱,在较低功率(15W)时快速升温将有机汞氧化为无机汞,测定总汞含量;加热柱为室温时,测定无机汞含量,二者之差为有机汞。对各种实验参数和干扰情况进行了详细研究。无机汞的检出限为0.036μg/L;样品分析精密度(RSD)为2.4%(n=11);有机汞的检出限为0.043μg/L,样品分析精密度(RSD)为3.6%(n=11)。 相似文献
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A new idea is put forward to modify the Clarkson-Kruskal (CK) direct method. Using the usual CK direct method to a coupled KdV system, two types of usual similarity reductions can be obtained. However, the application of the modified CK direct method leads to three types of new similarity reductions different from the usual ones. 相似文献