排序方式: 共有22条查询结果,搜索用时 15 毫秒
1.
Lin Bai Mingjiang Sun Jianguo AnDavid Q. Liu Ted K. ChenAlireza S. Kord 《Journal of chromatography. A》2010,1217(3):302-306
Many pharmaceutical genotoxic impurities are neutral molecules. Trace level analysis of these neutral analytes is hampered by their poor ionization efficiency in mass spectrometry (MS). Two analytical approaches including chemical derivatization and coordination ion spray-MS were developed to enhance neutral analyte detection sensitivity. The chemical derivatization approach converts analytes into highly ionizable or permanently charged derivatives, which become readily detectable by MS. The coordination ion spray-MS method, on the other hand, improves ionization by forming neutral-ion adducts with metal ions such as Na+, K+, or NH4+ which are introduced into the electrospray ionization source. Both approaches have been proven to be able to enhance the detection sensitivity of neutral pharmaceuticals dramatically. This article demonstrates the successful applications of the two approaches in the analysis of four pharmaceutical genotoxic impurities identified in a single drug development program, of which two are non-volatile alkyl chlorides and the other two are epoxides. 相似文献
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In this study, biological properties of the essential oil isolated from seeds of Foeniculum vulgare (F. vulgare) were evaluated. GC-MS analysis revealed Trans-Anethole (80.63%), L-Fenchone (11.57%), Estragole (3.67%) and Limonene (2.68%) were the major compounds of the essential oil. Antibacterial activity of the essential oil against nine Gram-positive and Gram-negative strains was studied using disc diffusion and micro-well dilution assays. Essential oil exhibited the antibacterial activity against three Gram-negative strains of Pseudomonas aeruginosa, Escherichia coli, and Shigella dysenteriae. The preliminary study on toxicity of seed oil was performed using Brine Shrimp lethality test (BSLT). Results indicated the high toxicity effect of essential oil (LC50 = 10 μg/mL). In vitro anticancer activity of seed oil was investigated against human breast cancer (MDA-Mb) and cervical epithelioid carcinoma (Hela) cell lines by MTT assay. Results showed the seed oil behave as a very potent anticancer agent with IC50 of lower than 10 μg/mL in both cases. 相似文献
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Chemically and Biologically Harmless versus Harmful Ferritin/Copper–Metallothionein Couples
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Dr. Fernando Carmona Daniela Mendoza Scheghajegh Kord Michela Asperti Prof. Paolo Arosio Prof. Sílvia Atrian Prof. Mercè Capdevila Prof. Jose M. Dominguez‐Vera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):808-813
The simultaneous measurement of the decrease of available FeII ions and the increase of available FeIII ions allowed the analysis of the ferroxidase activity of two distinct apoferritins. Although recombinant human apoferritin (HuFtH) rapidly oxidizes FeII to FeIII, this iron is not properly stored in the ferritin cavity, as otherwise occurs in horse‐spleen H/L‐apoferritin (HsFt; H=heavy subunit, L=light subunit). Iron storage in these apoferritins was also studied in the presence of two copper‐loaded mammalian metallothioneins (MT2 and MT3), a scenario that occurs in different brain‐cell types. For HuFtH, unstored FeIII ions trigger the oxidation of Cu–MT2 with concomitant CuI release. In contrast, there is no reaction with Cu–MT2 in the case of HsFt. Similarly, Cu–MT3 does not react during either HuFtH or HsFt iron reconstitution. Significantly, the combination of ferritin and metallothionein isoforms reported in glia and neuronal cells are precisely those combinations that avoid a harmful release of FeII and CuI ions. 相似文献
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András Sápi Róbert Rémiás Zoltán Kónya ákos Kukovecz Krisztián Kordás Imre Kiricsi 《Reaction Kinetics and Catalysis Letters》2009,96(2):379-389
Nickel catalysts supported on various carbon materials such as multiwall carbon nanotubes, shortened length carbon nanotubes,
graphite and amorphous carbon were synthesized, characterized and tested in cyclohexene hydrogenation reaction. We have found
that carbon nanotube supports are superior to graphite and amorphous carbon both in terms of catalytic activity and stability. 相似文献
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Mahya Mohammadi Ahmad Sheykhi Mahdi Kord Zangeneh 《The European Physical Journal C - Particles and Fields》2018,78(12):984
We analytically and numerically study the properties of one-dimensional holographic p-wave superconductors in the presence of backreaction. We employ the Sturm–Liouville eigenvalue problem for the analytical calculation and the shooting method for the numerical investigations. We apply the \(\hbox {AdS}_{{3}}\)/\(\hbox {CFT}_{{2}}\) correspondence and determine the relation between the critical temperature \(T_{c}\) and the chemical potential \(\mu \) for different values of the mass m of a charged spin-1 field \(\rho _{\mu }\) and backreacting parameters. We observe that the data of both analytical and numerical studies are in good agreement. We find that increasing the backreaction and the mass parameter causes the greater values for \({T_{c}}/{\mu }\). Thus, it makes the condensation harder to form. In addition, the analytical and numerical approaches show that the value of the critical exponent \( \beta \) is 1 / 2, which is the same as in the mean field theory. Moreover, both methods confirm the existence of a second order phase transition. 相似文献
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Lianming Wu David Q. Liu Alireza S. Kord 《Journal of the American Society for Mass Spectrometry》2010,21(10):1802-1813
Ethylnitrilium ion can be generated by protonation of acetonitrile (when used as the LC-MS mobile phase) under the conditions
of atmospheric pressure ionizations, including electrospray ionization (ESI) and atmospheric pressure chemical ionization
(APCI) as well as atmospheric pressure photoionization (APPI). Ethylnitrilium ion (
CH3 - C o \mathop N+ HCH_3 - C \equiv \mathop N\limits^ + H and its canonical form
CH3 - \mathop C+ = NHCH_3 - \mathop C\limits^ + = NH) is shown to efficiently undergo the gas-phase Meerwein reaction with epoxides. This reaction proceeds by the initial formation
of an oxonium ion followed by three-to-five-membered ring expansion via an intramolecular nucleophilic attack to yield the
Meerwein reaction products. The density functional theory (DFT) calculations at the B3LYP/6-311 + G(d,p) level show that the
gas-phase Meerwein reaction is thermodynamically favorable. Collision-induced dissociation (CID) of the Meerwein reaction
products yields the net oxygen-by-nitrogen replacement of epoxides with a characteristic mass shift of 1 Da, providing evidence
for the cyclic nature of the gas-phase Meerwein reaction products. The gas-phase Meerwein reaction offers a novel and fast
LC-MS approach for the direct analysis of epoxides that might be of genotoxic concern during drug development. Understanding
and utilizing this unique gas-phase ion/molecule reaction, the sensitivity and selectivity for quantitation of epoxides can
be enhanced. 相似文献
8.
Engaging Copper(III) Corrole as an Electron Acceptor: Photoinduced Charge Separation in Zinc Porphyrin–Copper Corrole Donor–Acceptor Conjugates
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Dr. Thien H. Ngo David Zieba Whitney A. Webre Gary N. Lim Prof. Dr. Paul A. Karr Scheghajegh Kord Dr. Shangbin Jin Dr. Katsuhiko Ariga Marzia Galli Prof. Dr. Steve Goldup Dr. Jonathan P. Hill Prof. Dr. Francis D'Souza 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(4):1301-1312
An electron‐deficient copper(III) corrole was utilized for the construction of donor–acceptor conjugates with zinc(II) porphyrin (ZnP) as a singlet excited state electron donor, and the occurrence of photoinduced charge separation was demonstrated by using transient pump–probe spectroscopic techniques. In these conjugates, the number of copper corrole units was varied from 1 to 2 or 4 units while maintaining a single ZnP entity to observe the effect of corrole multiplicity in facilitating the charge‐separation process. The conjugates and control compounds were electrochemically and spectroelectrochemically characterized. Computational studies revealed ground state geometries of the compounds and the electron‐deficient nature of the copper(III) corrole. An energy level diagram was established to predict the photochemical events by using optical, emission, electrochemical, and computational data. The occurrence of charge separation from singlet excited zinc porphyrin and charge recombination to yield directly the ground state species were evident from the diagram. Femtosecond transient absorption spectroscopy studies provided spectral evidence of charge separation in the form of the zinc porphyrin radical cation and copper(II) corrole species as products. Rates of charge separation in the conjugates were found to be of the order of 1010 s?1 and increased with increasing multiplicity of copper(III) corrole entities. The present study demonstrates the importance of copper(III) corrole as an electron acceptor in building model photosynthetic systems. 相似文献
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M. Haddadi Moghaddam B. Azadegan A. F. Kord W. M. Alberico 《The European Physical Journal C - Particles and Fields》2018,78(3):255
In this study, we investigate the impact of the magnetic field on the evolution of the transverse flow of QGP matter in the magneto-hydrodynamic (MHD) framework. We assume that the magnetic field is perpendicular to the reaction plane and then we solve the coupled Maxwell and conservation equations in (1+1D) transverse flow, within the Bjorken scenario. We consider a QGP with infinite electrical conductivity. First, the magnetic effects on the QGP medium at mid-rapidity are investigated at leading order; then the time and space dependence of the energy density, velocity and magnetic field in the transverse plane of the ideal magnetized hot plasma are obtained. 相似文献