A fast and simple method for simultaneous detection and quantification of the medicinally important E- and Z-guggulsterone from raw oleogum-resin of Commiphora wightii by UPLC was developed. Both E- and Z-guggulsterone were extracted from naturally occurring resin samples using ethyl acetate and methanol. Chromatographic separation of the analytes and their respective standards were performed on an Acquity UPLC BEH C18 column followed by UV as well as a triple quadrupole detector in positive ionization mode. A linear gradient elution profile followed; mobile phase consisted of acetonitrile and 2 mM ammonium acetate in water. The method was validated over a range of 6.25 to 100 ng mL−1 for both the guggulsterones. The calibration curves were linear with correlation coefficients of 0.9998 for E-guggulsterone and 0.9999 for Z-guggulsterone. The LOD and LOQ were 1.65 and 5.02 ng mL−1 for E-guggulsterone and 2.57 and 7.79 ng mL−1 for Z-guggulsterone respectively. The average recovery of E-guggulsterone (104.63%) and Z-guggulsterone (104.33%) achieved from spiked samples were consistent and reproducible. The intra- and inter-day assay precision of the analytes over the entire concentration range was less than 2%. The developed method required only 6 min to complete a run including 1 min to equilibrate the system and hence suitable for high throughput applications. Efficiency, reliability and accuracy of the developed method were evaluated by analyzing resin sample from different C. wightii populations. The result of this study offers improvement in terms of speed and sensitivity as compared to previously reported methods.
A new genetic algorithms based multi-objective optimization algorithm (NMGA) has been developed during study. It works on a neighborhood concept in the functional space, utilizes the ideas on weak dominance and ranking and uses its own procedures for population sizing. The algorithm was successfully tested with some standard test functions, and when applied to a real-life data of the hot-rolling campaign of an integrated steel plant, it outperformed another recently developed multi-objective evolutionary algorithm. 相似文献
An enhanced one-pot synthesis of new functionalized 5,6-dihydro-5,5-dimethyl-2-phenyl-2H-pyridazino[3,4,5-kl]acridin-1(4H)-one derivatives with different substituted patterns by using mesoporous MCM-41 catalyst via a ring opening/ring closure reaction process has been established. This MCM-41 silica catalyst has been synthesized and characterized using an array of sophisticated analytical techniques like BET, XRD, UHRTEM, etc. This reaction could be conducted from inexpensive substrates within short period under neat reflux conditions. Compared with the usual methods, the remarkable advantages of this method are milder reaction conditions, operational simplicity, higher yields, short reaction times and an environmentally friendly procedure. 相似文献
Batch extraction of uranium(VI) from uranyl nitrate solutions using TiAP in ionic liquids ([BMIM]PF6 and [HMIM]PF6) is studied. Effects of acidity, TiAP concentration in ionic liquid and temperature on distribution coefficient are studied. Results show that distribution coefficient increases with an increase in acidity and reduces with an increase in the alkyl chain length of the cation of the ionic liquid. Extraction of uranium(VI) by TiAP-[HMIM]PF6 system is found to involve two molecules of the extractant per metal ion and extraction is found to change from being exothermic to endothermic as the percentage of the extractant is increased. 相似文献
The study of protein conformational changes in the presence of surfactants and lipids is important in the context of protein
folding and misfolding. In the present study, we have investigated the mechanism of the protein conformational change coupled
with aggregation leading to size growth of Hen Egg White Lysozyme (HEWL) in the presence of an anionic detergent such as sodium
dodecyl sulphate (SDS) in alkaline pH. We have utilized intrinsic protein fluorescence (tryptophan) and extrinsic fluorescent
reporters such as 8-anilinonaphthalene-1-sulfonic acid (ANS), dansyl and fluorescein to follow the protein conformational
change in real-time. By analyzing the kinetics of fluorescence intensity and anisotropy of multiple fluorescent reporters,
we have been able to delineate the mechanism of surfactant-induced aggregation of lysozyme. The kinetic parameters reveal
that aggregation proceeds with an initial fast-phase (conformational change) followed by a slow-phase (self-assembly). Our
results indicate that SDS, below critical micelle concentration, induces conformational expansion that triggers the aggregation
process at a micromolar protein concentration range. 相似文献
Competition with magnetism is at the heart of high-temperature superconductivity, most intensely felt near a vortex core. To investigate vortex magnetism we have developed a spatially resolved probe based upon NMR spin-lattice-relaxation spectroscopy. With this approach we have found a spin-density wave associated with the vortex core in Bi(2)Sr(2)CaCu(2)O(8+y), similar to checkerboard patterns in the local density of electronic states reported from scanning tunneling microscope experiments. We have determined both the spin-modulation amplitude and decay length from the vortex core in fields up to H=30 T. 相似文献
Photon correlation spectroscopy and rheological measurements are performed to investigate the microscopic dynamics and mechanical
responses of aqueous solutions of triblock copolymers and aqueous mixtures of triblock copolymers and anionic surfactants.
Increasing the concentration of triblock copolymers results in a sharp increase in the magnitude of the complex moduli characterising
the samples. This is understood in terms of the changes in the aggregation and packing behaviours of the copolymers and the
constraints imposed upon their dynamics due to increased close packing. The addition of suitable quantities of an anionic
surfactant to a strongly elastic copolymer solution results in a decrease in the complex moduli of the samples by several
decades. It is argued that the shape anisotropy and size polydispersity of the micelles comprising mixtures cause dramatic
changes in the packing behaviour, resulting in sample unjamming and the observed decrease in complex moduli. Finally, a phase
diagram is constructed in the temperature-surfactant concentration plane to summarise the jamming-unjamming behaviour of aggregates
constituting triblock copolymer-anionic surfactant mixtures. 相似文献