1 Introduction and Main Results For n≥2,let M be a n-dimensional connected smooth manifold.We take a fixed smooth measure on M with strictly positive density,and write dx as the measure when we integrate.Also,we simp...1 Introduction and Main Results For n≥2,let M be a n-dimensional connected smooth manifold.We take a fixed smooth measure on M with strictly positive density,and write dx as the measure when we integrate.Also,we simply denote the measure of a set E?M by|E|.展开更多
1 Introduction and Main Results.For n≥2,we consider the following Dirichlet eigenvalue problem.{-△μu=λu,χ∈Ω;u=0,χ∈?Ω}(1.1)on a bounded open domainΩR^n,with smooth boundary?Ω,where△μis a degenerate ellipt...1 Introduction and Main Results.For n≥2,we consider the following Dirichlet eigenvalue problem.{-△μu=λu,χ∈Ω;u=0,χ∈?Ω}(1.1)on a bounded open domainΩR^n,with smooth boundary?Ω,where△μis a degenerate elliptic operator generated by a system of real vector fields X=(X1,X2,…,Xn),namely.展开更多
AIM： To improve the absorption and bioavailability of baicalin using a nanocrystal （or nanosuspension） drug delivery system. METHODS： A tandem, ultrasonic-homogenization-fluid bed drying technology was applied to ...AIM： To improve the absorption and bioavailability of baicalin using a nanocrystal （or nanosuspension） drug delivery system. METHODS： A tandem, ultrasonic-homogenization-fluid bed drying technology was applied to prepare baicalin-nanocrystal dried powders, and the physicochemical properties of baicalin-nanocrystals were characterized by scanning electron microscopy, photon correlation spectroscopy, powder X-ray diffraction, physical stability, and solubility experiments. Furthermore, in situ intestine single-pass perfusion experiments and pharmacokinetics in rats were performed to make a comparison between the microcrystals of baicalin and pure baicalin in their absorption properties and bioavailability in vivo. RESULTS： The mean particle size of baicalin-nanocrystals was 236 nm, with a polydispersity index of 0.173, and a zeta potential value of-34.8 mV, which provided a guarantee for the stability of the reconstituted nanosuspension. X-Ray diffraction results indicated that the crystallinity of baicalin was decreased through the ultrasonic-homogenization process. Physical stability experiments showed that the prepared baicalin-nanocrystals were sufficiently stable. It was shown that the solubility of baicalin in the form of nanocrystals, at 495 ug·mL-1, was much higher than the baicalin-microcrystals and the physical mixture （135 and 86.4 ug·mL- 1, respectively）. In situ intestine perfusion experiments demonstrated a clear advantage in the dissolution and absorption characteristics for baicalin-nanocrystals compared to the other formulations. In addition, after oral administration to rats, the particle size decrease from the micron to nanometer range exhibited much higher in vivo bioavailability （with the AUC（0-t） value of 206.96 ± 21.23 and 127.95 ± 14.41 mg·L-1·h-1, respectively）. CONCLUSION： The nanocrystal drug delivery system using an ultrasonic-homogenization-fluid bed drying process is able to improve the absorption and in vivo bioavailability of baicalin, compared with pure baicalin coarse powder and micronized baicalin.展开更多
基金Supported by National Natural Science Foundation of China(1163101111626251)China Postdoctoral Science Foundation(2021M703282)。
文摘1 Introduction and Main Results For n≥2,let M be a n-dimensional connected smooth manifold.We take a fixed smooth measure on M with strictly positive density,and write dx as the measure when we integrate.Also,we simply denote the measure of a set E?M by|E|.
基金supported by National Natural Science Foundation of China(11631011,11626251).
文摘1 Introduction and Main Results.For n≥2,we consider the following Dirichlet eigenvalue problem.{-△μu=λu,χ∈Ω;u=0,χ∈?Ω}(1.1)on a bounded open domainΩR^n,with smooth boundary?Ω,where△μis a degenerate elliptic operator generated by a system of real vector fields X=(X1,X2,…,Xn),namely.
基金supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry(Nos.20101561,NCET-11-0114)the Beijing Natural Science Foundation(No.7122176)
文摘AIM： To improve the absorption and bioavailability of baicalin using a nanocrystal （or nanosuspension） drug delivery system. METHODS： A tandem, ultrasonic-homogenization-fluid bed drying technology was applied to prepare baicalin-nanocrystal dried powders, and the physicochemical properties of baicalin-nanocrystals were characterized by scanning electron microscopy, photon correlation spectroscopy, powder X-ray diffraction, physical stability, and solubility experiments. Furthermore, in situ intestine single-pass perfusion experiments and pharmacokinetics in rats were performed to make a comparison between the microcrystals of baicalin and pure baicalin in their absorption properties and bioavailability in vivo. RESULTS： The mean particle size of baicalin-nanocrystals was 236 nm, with a polydispersity index of 0.173, and a zeta potential value of-34.8 mV, which provided a guarantee for the stability of the reconstituted nanosuspension. X-Ray diffraction results indicated that the crystallinity of baicalin was decreased through the ultrasonic-homogenization process. Physical stability experiments showed that the prepared baicalin-nanocrystals were sufficiently stable. It was shown that the solubility of baicalin in the form of nanocrystals, at 495 ug·mL-1, was much higher than the baicalin-microcrystals and the physical mixture （135 and 86.4 ug·mL- 1, respectively）. In situ intestine perfusion experiments demonstrated a clear advantage in the dissolution and absorption characteristics for baicalin-nanocrystals compared to the other formulations. In addition, after oral administration to rats, the particle size decrease from the micron to nanometer range exhibited much higher in vivo bioavailability （with the AUC（0-t） value of 206.96 ± 21.23 and 127.95 ± 14.41 mg·L-1·h-1, respectively）. CONCLUSION： The nanocrystal drug delivery system using an ultrasonic-homogenization-fluid bed drying process is able to improve the absorption and in vivo bioavailability of baicalin, compared with pure baicalin coarse powder and micronized baicalin.
