An Adjusted Frequency-Domain Algorithm for Arc Array Bistatic SAR Data with One-Moving Transmitter.

Arc array synthetic aperture radar (AA-SAR), which can observe the scene in all directions, breaks through the single view of traditional SAR. However, the concealment of AA-SAR is poor. To mitigate this, arc array bistatic SAR (AA-BiSAR) with the moving transmitter is proposed, it has the advantages of good concealment and can expand the imaging scene, and improve the flexibility of the system. The imaging geometry including the signal model is established, and a range frequency-domain algorithm based on keystone transform (KT) is proposed in this paper. In the first step, the slant range equation is approximated by Taylor series expansion to compensate for the residual phase caused by the transmitter motion. In the second step, the range cell migration between the range and azimuth is eliminated through the KT method in the range frequency-domain. In the third step, using the data after range cell migration correction in step 2, an azimuth pulse compression is performed to obtain the focused image. In addition, the spatial resolution of the AA-BiSAR system is analyzed in detail. Finally, three simulation results verify the effectiveness of the proposed algorithm and the change in the spatial resolution.

pH-Responsive Zwitterionic Copolymer DHA-PBLG-PCB for Targeted Drug Delivery: A Computer Simulation Study.

In this work, the self-assembled behaviors of zwitterionic copolymer docosahexaenoic acid- b-poly(γ-benzyl-l-glutamate)- b-poly(carboxybetaine methacrylate) (DHA-PBLG-PCB) and the loading and release mechanism of the anticancer drug doxorubicin (DOX) was investigated via computer simulations. The effects of polymer concentration, drug content, and pH on polymeric micelles were explored by dissipative particle dynamics (DPD) simulations. Simulation results show that DHA-PBLG15-PCB10 can self-assemble into core-shell micelles; in addition, the drug-loaded micelles have a pH-responsive feature. DOX can be encapsulated into the core-shell micelle under normal physiological pH conditions, whereas it can be released under acidic pH conditions. The self-assembled behaviors of copolymer DHA-PBLG-PEG were also studied to have a comparison with those of DHA-PBLG-PCB. The DHA-PBLG15-PCB10 system has a stable structure and it has a great potential to serve as drug delivery vehicles for targeted drug delivery.

Mechanisms on formation of hierarchically porous carbon and its adsorption behaviors.

Using simple one-step carbonization-activation, the residues of paulownia flowers are employed as a precursor to prepare hierarchically porous activated carbon. After investigating the optimum conditions, the obtained paulownia flowers based activated carbon (PFAC) is characterized by Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscope, Brunauer-Emmett-Teller specific surface area analysis (S(BET)), thermo gravimetric analysis, and X-ray photoelectron spectroscopy. The PFAC owns a high specific surface area of 1,053 m(2)/g as well as a hierarchically porous structure with a combination of micro-, meso- and macropores. The pore-forming mechanism is discussed according to results of characterization. Using methylene blue as model dye, the adsorption behaviors of PFAC were investigated. We found that the dye could be rapidly adsorbed by hierarchically porous PFAC, and the adsorption capacity of PFAC reached 300 mg/g.