The Experts below are selected from a list of 1224303 Experts worldwide ranked by ideXlab platform
Wanli Zhao - One of the best experts on this subject based on the ideXlab platform.
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qualitative and quantitative analysis of major triterpenoids in alismatis rhizoma by high performance liquid chromatography diode array detector quadrupole time of flight mass spectrometry and ultra performance liquid chromatography triple quadrupole mass spectrometry
Molecules, 2015Co-Authors: Wanli Zhao, Xiaoqiang Huang, Fangfang Zhang, Sainan Chen, Mingqing HuangAbstract:Alismatis Rhizoma (AMR) is a well-known natural medicine with a long history in Chinese medicine and has been commonly used for treating a wide range of ailments related to dysuria, edema, nephropathy, hyperlipidaemia, diabetes, inflammation as well as tumors in clinical applications. Most beneficial effects of AMR are attributed to the presence of protostane terpenoids, the major active ingredients of Alismatis Rhizoma (AMR). In this study, a systematic high performance liquid chromatography/diode-array detector/quadrupole-time-of-flight mass spectrometry (HPLC-DAD-Q-TOF MS) and ultra-performance liquid chromatography/triple quadrupole mass spectrometry (UPLC-QqQ MS) method was developed for qualitative and quantitative analyses of the major AMR triterpenoids. First, a total of 25 triterpenoid components, including 24 known compounds and one new compound were identified by comparison with UV spectra, molecular ions and fragmentation behaviors of reference standards or the literature. Second, an efficient method was established for the rapid simultaneous determination of 14 representative triterpenoids by UPLC-QqQ MS. Forty-three batches of AMR were analyzed with linearity (r, 0.9980-0.9999), intra-day precision (RSD, 1.18%-3.79%), inter-day precision (RSD, 1.53%-3.96%), stability (RSD, 1.32%-3.97%), repeatability (RSD, 2.21%-4.25%), and recovery (98.11%-103.8%). These results indicated that new approaches combining HPLC-DAD-Q-TOF MS and UPLC-QqQ MS are applicable in the qualitative and quantitative analysis of AMR.
Toshifumi Futamase - One of the best experts on this subject based on the ideXlab platform.
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a new weak lensing shear analysis method using ellipticity defined by 0th order moments
Astronomy and Astrophysics, 2015Co-Authors: Yuki Okura, Toshifumi FutamaseAbstract:We developed a new method that uses ellipticity defined by 0th order moments (0th-ellipticity) for weak gravitational lensing shear analysis. Although there is a strong correlation between the ellipticity calculated using this approach and the usual ellipticity defined by the 2nd order moment, the ellipticity calculated here has a higher signal-to-noise ratio because it is weighted to the central region of the image. These results were confirmed using data for Abell 1689 from the Subaru telescope. For shear analysis, we adopted the ellipticity of re-smeared artificial image method for point spread function correction, and we tested the precision of this 0th-ellipticity with simple simulation, then we obtained the same level of precision with the results of ellipticity defined by quadrupole moments. Thus, we can expect that weak lensing analysis using 0 shear will be improved in proportion to the statistical error.
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a new weak lensing shear analysis method using ellipticity defined by 0th order moments
arXiv: Cosmology and Nongalactic Astrophysics, 2014Co-Authors: Yuki Okura, Toshifumi FutamaseAbstract:We developed a new method that uses ellipticity defined by 0th order moments (0th-ellipticity) for weak gravitational lensing shear analysis. Although there is a strong correlation between the ellipticity calculated using this approach and the usual ellipticity defined by the 2nd order moment, the ellipticity calculated here has a higher signal-to-noise ratio because it is weighted to the central region of the image. These results were confirmed using data for Abell 1689 from the Subaru telescope. For shear analysis, we adopted the ellipticity of re-smeared artificial image (ERA) method for point spread function (PSF) correction, and we tested the precision of this 0th-ellipticity with simple simulation, then we obtained the same level of precision with the results of ellipticity defined by quadrupole moments. Thus, we can expect that weak lensing analysis using 0 shear will be improved in proportion to the statistical error.
Jorgen Skibsted - One of the best experts on this subject based on the ideXlab platform.
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11b chemical shift anisotropies in borates from 11b mas mqmas and single crystal nmr spectroscopy
Journal of Physical Chemistry A, 2004Co-Authors: Michael Ryan Hansen, And Hans J Jakobsen, Thomas Vosegaard, Jorgen SkibstedAbstract:11B chemical shift anisotropies (CSAs) have been obtained for tetrahedral and trigonal boron sites in tetraphenyl borates, datolite (CaBSiO4(OH)), danburite (CaB2Si2O8), colemanite (CaB3O4(OH)3·H2O), borax (Na2B4O7·10H2O), and Li2B4O7 from solid-state 11B NMR spectra recorded at 14.1 T. These parameters along with 11B quadrupole couplings and the relative orientation of the quadrupole coupling and CSA tensors have been determined from either the manifold of spinning sidebands observed for the satellite transitions in 11B MAS NMR spectra or single-crystal NMR spectra of the satellite transitions. Furthermore, the potential of the MQMAS experiment for determination of small 11B CSAs is illustrated for the trigonal boron site in Li2B4O7. The 11B single-crystal NMR spectra of the satellite transitions are strongly dominated by the first-order quadrupolar interaction, which may prevent a direct determination of small CSAs. However, an improved precision of the CSA parameters and the Euler angles, describing th...
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2h chemical shift anisotropies from high field 2h mas nmr spectroscopy
Journal of Magnetic Resonance, 2003Co-Authors: Anne Hauch, Henrik Bildsoe, Hans J Jakobsen, Jorgen SkibstedAbstract:Abstract 2H chemical shift anisotropies (CSAs) have been determined for the first time for polycrystalline samples employing 2H MAS NMR spectroscopy at high magnetic field strength (14.1 T). The 2H CSA is reflected as distinct asymmetries in the manifold of spinning sidebands (ssbs) observed for the two overlapping single-quantum transitions. Least-squares fitting to the manifold of ssbs allows determination of the 2H CSA parameters along with the quadrupole coupling parameters. This is demonstrated for KD2PO4, ND4D2PO4, KDSO4, KDCO3, α-(COOD)2, α-(COOD)2 · 2D2O, and boehmite (AlOOD) which exhibit 2H shift anisotropies in the range 13 ⩽ δσ ⩽ 27 ppm. For fixed values of the shift anisotropy and the 2H quadrupole coupling it is shown that the precision of the CSA parameters depends strongly on the asymmetry parameter (ηQ) for the quadrupole coupling tensor, giving the highest precision for ηQ≈0. The 2H CSA parameters (δσ and ησ) are in good agreement with 1H CSA data reported in the literature for the corresponding protonated samples from 1H NMR spectra employing various homonuclear decoupling techniques. The determination of 2H quadrupole coupling parameters and 2H (1H) CSAs from the same 2H MAS NMR experiment may be particularly useful in studies of hydrogen bonding since the 2H quadrupole coupling constant and the CSA appear to characterize bond lengths in a hydrogen bond in a different manner.
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51v mas nmr investigation of 51v quadrupole coupling and chemical shift anisotropy in divalent metal pyrovanadates
Journal of Physical Chemistry B, 2001Co-Authors: Ulla Gro Nielsen, And Hans J Jakobsen, Jorgen SkibstedAbstract:Magnitudes and relative orientations of 51V quadrupole coupling and chemical shift tensors have been determined from 51V magic-angle spinning (MAS) NMR spectra at 14.1 T for seven divalent metal pyrovanadates: α- and β-Mg2V2O7, Ca2V2O7, α-Zn2V2O7, Cd2V2O7, BaCaV2O7, and α-BaZnV2O7. This has been accomplished by least-squares fitting of the integrated spinning sideband intensities observed for the central and satellite transitions employing spectral widths up to 4 MHz. Numerical error analysis of the optimized data reveals that the five NMR parameters characterizing the magnitudes of the quadrupole coupling and chemical shift tensors are obtained with high precision while somewhat larger error limits are observed for the three Euler angles, describing the relative orientation of the two tensors. The optimized data exhibit a significantly higher precision when compared to earlier reported parameters for some of the pyrovanadates, determined from 51V static-powder or MAS NMR of the central transition only. ...
Yun Chen - One of the best experts on this subject based on the ideXlab platform.
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high performance liquid chromatography atmospheric pressure chemical ionisation mass spectrometry determination of zaleplon in human plasma
Journal of Pharmaceutical and Biomedical Analysis, 2006Co-Authors: Beibei Zhang, Zunjian Zhang, Yuan Tian, Yun ChenAbstract:Abstract A sensitive and specific liquid chromatography–atmospheric pressure chemical ionisation-mass spectrometry (LC–APCI-MS) method has been developed and validated for the identification and quantification of zaleplon in human plasma using estazolam as an internal standard (IS). After the addition of estazolam and 2.0 M sodium hydroxide solution, plasma samples were extracted with ethyl acetate and then the organic layer was evaporated to dryness. The reconstituted solution of the residue was injected onto a prepacked Shim-pack VP-ODS C 18 (250 mm × 2.0 mm i.d.) column and chromatographed with a mobile phase comprised of methanol:water (70:30) at a flow-rate of 0.2 ml/min. Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring (SIM) mode via atmospheric pressure chemical ionization (APCI) source. The mean standard curve was linear ( r = 0.9991) over the concentration range of 0.2–100 ng/ml and had good back-calculated accuracy and precision. The intra-day and inter-day precisions were within 10% relative standard deviation and accuracy ranged from 85% to 115%. The limit of detection was 0.1 ng/ml. The validated LC–APCI-MS method has been used successfully to study zaleplon pharmacokinetic, bioavailability and bioequivalence in 18 adult volunteers.
Mingqing Huang - One of the best experts on this subject based on the ideXlab platform.
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qualitative and quantitative analysis of major triterpenoids in alismatis rhizoma by high performance liquid chromatography diode array detector quadrupole time of flight mass spectrometry and ultra performance liquid chromatography triple quadrupole mass spectrometry
Molecules, 2015Co-Authors: Wanli Zhao, Xiaoqiang Huang, Fangfang Zhang, Sainan Chen, Mingqing HuangAbstract:Alismatis Rhizoma (AMR) is a well-known natural medicine with a long history in Chinese medicine and has been commonly used for treating a wide range of ailments related to dysuria, edema, nephropathy, hyperlipidaemia, diabetes, inflammation as well as tumors in clinical applications. Most beneficial effects of AMR are attributed to the presence of protostane terpenoids, the major active ingredients of Alismatis Rhizoma (AMR). In this study, a systematic high performance liquid chromatography/diode-array detector/quadrupole-time-of-flight mass spectrometry (HPLC-DAD-Q-TOF MS) and ultra-performance liquid chromatography/triple quadrupole mass spectrometry (UPLC-QqQ MS) method was developed for qualitative and quantitative analyses of the major AMR triterpenoids. First, a total of 25 triterpenoid components, including 24 known compounds and one new compound were identified by comparison with UV spectra, molecular ions and fragmentation behaviors of reference standards or the literature. Second, an efficient method was established for the rapid simultaneous determination of 14 representative triterpenoids by UPLC-QqQ MS. Forty-three batches of AMR were analyzed with linearity (r, 0.9980-0.9999), intra-day precision (RSD, 1.18%-3.79%), inter-day precision (RSD, 1.53%-3.96%), stability (RSD, 1.32%-3.97%), repeatability (RSD, 2.21%-4.25%), and recovery (98.11%-103.8%). These results indicated that new approaches combining HPLC-DAD-Q-TOF MS and UPLC-QqQ MS are applicable in the qualitative and quantitative analysis of AMR.
