排序方式: 共有130条查询结果,搜索用时 15 毫秒
21.
A sensitive high-performance liquid chromatography-positive ion electrospray tandem mass spectrometry method was developed and validated for the quantification of clonidine in human plasma. Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M + H](+) ions, m/z 230 to 44 for clonidine and m/z 254 to 44 for the internal standard. The assay exhibited a linear dynamic range of 10-2000 pg/mL for clonidine in human plasma. The lower limit of quantification was 10 pg/mL with a relative standard deviation of less than 6.8%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.5 min for each sample made it possible to analyze more than 250 human plasma samples per day. The validated method was successfully used to analyze human plasma samples for application in pharmacokinetic studies. Copyright (c) 2008 John Wiley & Sons, Ltd. 相似文献
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Nirogi RV Kandikere VN Shukla M Mudigonda K Maurya S Komarneni P 《Biomedical chromatography : BMC》2007,21(2):209-216
A rapid high-performance liquid chromatography/positive ion electrospray tandem mass spectrometry method was developed and validated for the quantification of fexofenadine in human plasma using mosapride as internal standard. Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M+H]+ ions, m/z 502/466 for fexofenadine and m/z 422/198 for the IS. The method exhibited a linear dynamic range of 1-500 ng/mL for fexofenadine in human plasma. The lower limit of quantification was 1 ng/mL with a relative standard deviation of less than 5% for fexofenadine. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The total chromatographic run time of 2 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies. 相似文献
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Asuri P Karajanagi SS Yang H Yim TJ Kane RS Dordick JS 《Langmuir : the ACS journal of surfaces and colloids》2006,22(13):5833-5836
We have discovered a novel property of single-walled carbon nanotubes (SWNTs)-their ability to stabilize proteins at elevated temperatures and in organic solvents to a greater extent than conventional flat supports. Experimental results and theoretical analysis reveal that the stabilization results from the curvature of SWNTs, which suppresses unfavorable protein-protein lateral interactions. Our results also indicate that the phenomenon is not unique to SWNTs but could be extended to other nanomaterials. The protein-nanotube conjugates represent a new generation of active and stable catalytic materials with potential use in biosensors, diagnostics, and bioactive films and other hybrid materials that integrate biotic and abiotic components. 相似文献
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S.B. Bhanu Prashanth 《Journal of Non》2009,355(3):164-1206
The thermal properties and electrical-switching behavior of semiconducting chalcogenide SbxSe55−xTe45 (2 ? x ? 9) glasses have been investigated by alternating differential scanning calorimetry and electrical-switching experiments, respectively. The addition of Sb is found to enhance the glass forming tendency and stability as revealed by the decrease in non-reversing enthalpy ΔHnr, and an increase in the glass-transition width ΔTg. Further, the glass-transition temperature of SbxSe55−xTe45 glasses, which is a measure of network connectivity, exhibits a subtle increase, suggesting a meager network growth with the addition of Sb. The crystallization temperature is also observed to increase with Sb content. The SbxSe55−xTe45 glasses (2 ? x ? 9) are found to exhibit memory type of electrical switching, which can be attributed to the polymeric nature of network and high devitrifying ability. The metallicity factor has been found to dominate over the network connectivity and rigidity in the compositional dependence of switching voltage, which shows a profound decrease with the addition of Sb. 相似文献
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Nirogi R Kandikere V Komarneni P Aleti R Padala N Kalaikadhiban I 《Biomedical chromatography : BMC》2012,26(10):1150-1156
A sensitive high‐performance liquid chromatography–positive ion electrospray tandem mass spectrometry method was developed and validated for the quantification of ambrisentan in plasma. The analyte and the internal standard (armodafinil) were extracted from plasma by acetonitrile precipitation and they were separated on a reversed‐phase C18 column with a gradient program. The MS acquisition was performed with multiple reaction monitoring mode using the respective [M + H]+ ions, m/z 379–347 for ambrisentan and m/z 274–167 for the IS. The assay exhibited a linear dynamic range of 1–2000 ng/mL for ambrisentan in plasma. Acceptable precision (<10%) and accuracy (100 ± 8%) were obtained for concentrations over the standard curve range. The method was successfully applied to quantify ambrisentan concentrations in a rodent pharmacokinetic study after a single oral administration of ambrisentan at 2.5 mg/kg to rats. Following oral administration the maximum mean concentration in plasma (Cmax; 1197 ± 179 ng/mL) was achieved at 1.0 ± 0.9 h (Tmax), and the area under the curve (AUC) was 6013 ± 997 ng h/mL. Therefore, development of such a simple and sensitive method in rat plasma should translate into a method for ambrisentan in human plasma for clinical trials. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Let Ω be a bounded smooth domain inR
2. Letf:R→R be a smooth non-linearity behaving like exp{s
2} ass→∞. LetF denote the primitive off. Consider the functionalJ:H
0
1
(Ω)→R given by
It can be shown thatJ is the energy functional associated to the following nonlinear problem: −Δu=f(u) in Ω,u=0 on ρΩ. In this paper we consider the global compactness properties ofJ. We prove thatJ fails to satisfy the Palais-Smale condition at the energy levels {k/2},k any positive integer. More interestingly, we show thatJ fails to satisfy the Palais-Smale condition at these energy levels along two Palais-Smale sequences. These two sequences
exhibit different blow-up behaviours. This is in sharp contrast to the situation in higher dimensions where there is essentially
one Palais-Smale sequence for the corresponding energy functional. 相似文献
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Tong Gao Jester Itliong Sai Prashanth Kumar Zackerie Hjorth Issei Nakamura 《Journal of polymer science. Part A, Polymer chemistry》2021,59(21):2434-2457
Ionic liquid (IL)-containing polymers garner attention for electrochemical applications. This article overviews recent experimental and theoretical studies of polymer electrolytes that would be likely to cultivate new theoretical and computational frameworks for IL-containing polymers. The first two sections outline the uniqueness of ILs that differentiates them from inorganic salts in polymers and explore deviation from the concept of the metaphor “room-temperature molten salt.” Such distinct properties include (1) large intrinsic dipole moment and electronic polarizability, (2) hydrogen bonding, (3) π-interactions, (4) a broad distribution of charges over the entire ion, and (5) the anisotropy of the ions. Moreover, the complexity of these properties substantially increases when the ions are polymerized. Indeed, their exceptional features would overcome the hurdle due to a trade-off between ionic conductivity and mechanical robustness in inorganic salt-doped polymers. Given these facts, the rest of the article focuses on emerging trends in the study of the dielectric response, phase separation, ion conductivity, and mechanical robustness of the polymer electrolytes, highlighting outstanding observations in experiments that may inspire existing theory and simulation. Our discussion also includes improving computational complexity for IL-containing polymers. To this end, recent machine learning studies that consider ILs and polymer liquids are presented. 相似文献
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Nirogi RV Kandikere VN Shukla M Mudigonda K Maurya S Komarneni P 《Rapid communications in mass spectrometry : RCM》2006,20(12):1864-1870
A simple, sensitive and rapid high-performance liquid chromatography/positive ion electrospray tandem mass spectrometry method was developed and validated for the quantification of perindopril in human plasma. Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective [M+H](+) ions, m/z 369/172 for perindopril and m/z 417/234 for the internal standard. The method exhibited a linear dynamic range of 0.1-100 ng/mL for perindopril in human plasma. The lower limit of quantification was 0.1 ng/mL with a relative standard deviation of less than 6.1%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.0 min for each sample made it possible to analyze more than 450 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability and bioequivalence studies. 相似文献