The polymerization-induced phase-separation process of polyethersulfone (PES)-modified epoxy systems was monitored in situ continuously on a single sample throughout the entire curing process by using optical microscopes, time-resolved light scattering (TRLS), scanning electronic microscopes (SEM), and a rheometry instrument. At specific PES content a viscoelastic transformation process of phase inversion morphology to bicontinuous was found with an optical microscope. The rheological behavior during phase separation corresponds well with the morphology development. Light-scattering results monitoring the phase-separation process of systems with final phase inversion morphology show a typical exponential decay procedure of scattering vector qm. The characteristic relaxation time of phase separation can be described well by the WLF equation. 相似文献
C-11 (2-((7-Ethyl-3-methyl-8-(4-(2-(methyl(pyridin-2-yl)-amino)-ethoxy)phenyl)-2,6-dioxo-2,3,6,7-tetrahydro-1H-purin-1-yl)methyl)benzonitrile-one hydrochloride), which is based on the structure of rosiglitazone, was first synthesized in our laboratory and shown to be a promising anti-obesity drug candidate in our previous pharmacological study. Considering the importance of metabolic fate in vivo in the further development of drug candidates during early drug discovery, it is essential to characterize the metabolism of C-11 in vivo. In this work, a method based on ultra-high performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) was successfully developed to investigate the in vivo metabolic profile of C-11 in rats. Rat urine, feces, and plasma samples were collected from male Sprague–Dawley rats after intravenous administration of C-11 in a single dose of 30 mg kg−1 body weight. Besides the parent drug, a total of 25 metabolites (including 18 phase I and 7 phase II metabolites) were detected and tentatively identified by comparing their mass spectrometry profiles with those of C-11. This enabled the metabolic pathways of C-11 to be proposed for the first time. Our results revealed that N-depyridinylation, N-demethylation, hydroxylation, glucuronidation, and sulfate conjugation are the predominant metabolic pathways of C-11 in rats. The present study provides systematic information on the metabolism of C-11 in vivo, which should lead to a better understanding of its safety and mechanism of action.
Ansamitocin P‐3 is a potent anti‐tumor maytansinoid found in Actinosynnema pretiosum. However, due to the complexity of the fermentation broth of Actinomycete, how to effectively separate ansamitocin P‐3 is still a challenge. In this study, both analytical and preparative high‐performance counter‐current chromatography were successfully used to separate and purify ansamitocin P‐3 from fermentation broth. A total of 28.8 mg ansamitocin P‐3 with purity of 98.4% was separated from 160 mg crude sample of fermentation broth in less than 80 min with the two‐phase solvent system of hexane–ethyl acetate–methanol–water (0.6:1:0.6:1, v/v/v/v). The purity and structural identification were determined by HPLC, 1H NMR, 13C NMR and mass spectroscopy. 相似文献
Both analytical and preparative high-speed counter-current chromatography (HSCCC) were used to isolate and separate chemical bioactive constituents from the seeds of Millettia pachycarpa Benth, a famous traditional Chinese medicine. Three rotenoids and one isoflavone were successfully purified for the first time by HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (HEMWat) (1:0.8:1:0.6, v/v/v/v). The separation parameters were first performed on the analytical HSCCC and optimized conditions were then scaled up to preparative HSCCC. The separation produced 160.2 mg tephrosin, 14.6 mg 4',5'-dimethoxy-6,6-dimethylpyranoisoflavone, 109.4 mg deguelin, 6.7 mg 6a,12a-dehydrodeguelin with respective purities of 95, 93, 95, 95%, in one single run from 400 mg crude extract of the seeds of M. pachycarpa Benth. The purity of the isolated compounds was analyzed by high-performance liquid chromatography (HPLC) and their structures were identified by electrospray ionization mass spectrometry (ESI-MS); (1)H nuclear magnetic resonance ((1)H NMR) and (13)C nuclear magnetic resonance ((13)C NMR) analysis. This paper is an excellent example of the role that CCC is playing in isolating active compounds for pre-clinical trials of new chemical entities, even when scaling up between centrifuges from different manufacturers. 相似文献
A chirped laser pulse indicates that the laser frequency changes over the duration of the pulse: a positively (negatively) chirped pulse implies that the laser frequency increases (decreases) with time. In this paper, we use a simplified, fully relativistic hydrodynamic approach to simulate the influence of chirp on the propagation of a femtosecond relativistic laser pulse in underdense plasma. Based on this simplified cold‐fluid model, the influence of chirp on the main dynamics of the laser pulse, such as self‐steepening, red‐shift in the leading edge, variation of the frequency chirp, and the generated wakefields can be studied self‐consistently. The simulation results show that a pulse with a positive chirp results in a larger increment in the intensity parameter a0 when propagating a certain distance into an underdense plasma compared with an un‐chirped and a negatively chirped pulse, which is largely because of a much greater forward shift of the peak amplitude and more severe pulse self‐steepening effect due to the frequency red‐shift at the leading edge when exciting a plasma wave. The ponderomotive force, which relates to the first‐order differential of the laser pulse intensity envelope, is expected to be stronger for a positively chirped pulse because of its steeper leading edge and larger intensity parameter a0. As a result, the wakefield driven by the positively chirped laser pulse is more intense than that driven by an un‐chirped and a negatively chirped laser pulse, which is confirmed by our self‐consistent hydrodynamic simulation. 相似文献
A facile in situ replacement reaction route was successfully introduced for synthesizing Ag nanoshells with outer diameters of 40-50 nm and inner diameters of 20-30 nm using Co nanoparticles as sacrificial templates. The products were characterized by XRD, TEM, SAED, and UV-vis absorption spectra. The formation mechanism was also discussed. The reaction driving force comes from the large reduction potential gap between the Ag+/Ag and Co2+/Co redox couples, which results in the consumption of Co cores and the formation of a hollow cavity of Ag nanoshells. The UV-vis spectrum of this nanostructure exhibits a distinct difference from that of solid nanoparticles, which makes it a good candidate for application in photothermal materials. 相似文献
We report a simple and rapid biological approach to synthesize water-soluble and highly roughened “meatball”-like Au nanoparticles using green tea extract under microwave irradiation. The synthesized Au meatball-like nanoparticles possess excellent monodispersity and uniform size (250 nm in diameter). Raman measurements show that these tea-generated meatball-like gold nanostructures with high active surface areas exhibit a high enhancement of surface-enhanced Raman scattering. In addition, the Au meatball-like nanoparticles demonstrate good biocompatibility and remarkable in vitro stability at the biological temperature. Meanwhile, the factors that influence the Au meatball-like nanoparticles morphology are investigated, and the mechanisms behind the nonspherical shape evolution are discussed. 相似文献