12 research outputs found
E-Region Field-Aligned Irregularities in the Middle of a Solar Eclipse Observed by a Bistatic Radar
The Wuhan Ionospheric Oblique Backscatter Sounding System (WIOBSS) was applied as a bistatic radar to record the ionospheric E-region responses to a solar eclipse on 22 July 2009. The transmitter was located in Wuhan and the receiver was located in Huaian. The receiver observed anomalous echoes with larger Doppler shifts at the farther ranges compared with the echoes reflected by Es. According to the simulated ray propagation paths of the reflected and scattered waves, we considered that the anomalous echoes were scattered by E-region field-aligned irregularities (FAIs). The locations of the FAIs recorded by the WIOBSS were estimated with the International Geomagnetic Reference Field (IGRF) and the observed propagation parameters. These irregularities occurred at around the eclipse maximum and lasted for ~20–40 min. The steep plasma density gradient induced by the fast drop photo ionization under the lunar shadow was beneficial to the occurrence of gradient drift instability to generate the FAIs. They were different from the gravity wave-induced irregularities occurring in the recovery phase of the solar eclipse
E-Region Field-Aligned Irregularities in the Middle of a Solar Eclipse Observed by a Bistatic Radar
The Wuhan Ionospheric Oblique Backscatter Sounding System (WIOBSS) was applied as a bistatic radar to record the ionospheric E-region responses to a solar eclipse on 22 July 2009. The transmitter was located in Wuhan and the receiver was located in Huaian. The receiver observed anomalous echoes with larger Doppler shifts at the farther ranges compared with the echoes reflected by Es. According to the simulated ray propagation paths of the reflected and scattered waves, we considered that the anomalous echoes were scattered by E-region field-aligned irregularities (FAIs). The locations of the FAIs recorded by the WIOBSS were estimated with the International Geomagnetic Reference Field (IGRF) and the observed propagation parameters. These irregularities occurred at around the eclipse maximum and lasted for ~20–40 min. The steep plasma density gradient induced by the fast drop photo ionization under the lunar shadow was beneficial to the occurrence of gradient drift instability to generate the FAIs. They were different from the gravity wave-induced irregularities occurring in the recovery phase of the solar eclipse
High Drug Loading and Sub-Quantitative Loading Efficiency of Polymeric Micelles Driven by Donor–Receptor Coordination Interactions
Polymeric micelles
are extensively used for the delivery of hydrophobic
drugs, which, however, suffer from unsatisfactory drug loading, colloidal
uniformity, formulation stability, and drug release. Herein, we demonstrate
a convenient strategy to prepare micelles with ultrahigh drug loading
via the incorporation of polymer–drug coordination interactions.
An amphiphilic copolymer containing pendant phenylboronic acid as
electron acceptor unit was synthesized, which afforded donor–acceptor
coordination with doxorubicin to obtain micelles with ultrahigh drug
loading (∼50%), nearly quantitative loading efficiency (>95%),
uniform size, and colloidal stability. Besides, the encapsulated drug
can be effectively and selectively released in response to the high
reactive oxygen species levels in cancer cells, which potentiated
the anticancer efficacy and reduced systemic toxicity. Apart from
doxorubicin, the current platform could be extended to other drugs
with electron-donating groups (e.g., epirubicin and irinotecan), rendering
a simple and robust strategy for enabling high drug loading in polymeric
micelles and cancer-specific drug release