Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for cancer as well as non-cancer diseases, which involves the uptake of photosensitizers (PSs) by cancer cells followed by irradiation. The use of nanomaterials as carriers of PSs is a very promising approach to improve the development of PDT in clinical medicine. In this study, a novel folic acid-conjugated graphene oxide (GO) was strategically designed and prepared as targeting drug delivery system to achieve higher specificity. The second generation photosensitizer (PS) Chlorin e6 (Ce6) was effectively loaded into the system via hydrophobic interactions and π-π stacking. The nanocarriers can significantly increase the accumulation of Ce6 in tumor cells and lead to a remarkable photodynamic efficacy on MGC803 cells upon irradiation. These suggested that folic acid-conjugated GO loaded Ce6 had great potential as effective drug delivery system in targeting PDT.

Ferroelectric capacitive memories have not achieved the commercial success originally hoped for them in large volume because the area of the capacitors ("footprint") is too large to scale them up to gigabit density devices, [ 1 ] and a restoring pulse is required after a destructive readout. The non-destructive readout of the binary information is possible from the bipolar switching between high-and low-conductance of a ferroelectric diode under two opposite polarizations, as fi rst discovered by Blom et al. in PbTiO 3 perovskite thin fi lms [ 2 ] and later reported by Choi et al. in bulk BiFeO 3 single crystals and Pb(Zr,Ti)O 3 fi lms. [3][4][5] Important properties of such memory are the ultrafast operating speed depending on the polarization fl ipping time (1-2 ps in principle) [ 6 ] and the high ratio of resistance in the forward and reverse directions (3000:1). [ 7 ] However, most ferroelectrics are insulating wide bandgap semiconductors at room temperature, which limits the maximum diode current to the order of ≈ 20 mA cm − 2 . [ 2 , 3 ] Therefore, reaching a suffi cient ferroresistive diode current for the stable detection of memory status using the sense amplifi ers in modern memory circuitry with tiny cell size is a major challenge.In such strongly insulating ferroelectrics, suffi cient diode currents can, in fact, only be observed in ultrathin fi lms, where quantum mechanical tunneling current dominates [ 8 ] and is modulated by varying the tunneling barrier height along with the polarization reversal. Although this effect has been reproducibly demonstrated through local electron transport from an atomic force microscope (AFM) tip into ferroelectric thin fi lms, [9][10][11] the local-probe-based data storage is incompatible with current complementary metal-oxide semiconductor integration processes. Meanwhile, with macroscopic capacitor-type upper and lower electrodes capping the ultrathin ferroelectric layer, an overwhelming leakage current through existing defect-mediated leakage paths could swamp the tunneling current, thereby making the switching signal unreadable. In addition, large lattice-mismatch stresses in ultrathin epitaxial fi lms prevent their use as longtime retention memories due to preferred domain orientations. [ 12 ] One solution to these diffi culties has been to more broadly consider resistive switching effects in (non-ferroelectric) metal oxides. [13][14][15][16][17] However, most of these resistive switching effects are based on a certain type of defect (ionic or electronic) mediated phenomenon, suggesting the inherent diffi culty in precise control of the switching behavior. In contrast, ferroresistive switching behavior is based on the intrinsic switching of ferroelectric domains without invoking of charged defect migration and may, therefore, possess a fundamental merit over defectmediated mechanisms for achieving reliable performance requisite for commercial production once reliable fabrication parameters are established. A critical measure of such success using ferroelectric s...

Current-voltage hysteresis and switchable rectifying characteristics have been observed in epitaxial multiferroic BiFeO 3 ͑BFO͒ thin films. The forward direction of the rectifying current can be reversed repeatedly with polarization switching, indicating a switchable diode effect and large ferroelectric resistive switching. With analyzing the potential barriers and their variation with ferroelectric switching at the interfaces between the metallic electrodes and the semiconducting BFO, the switchable diode effect can be explained qualitatively by the polarization-modulated Schottky-like barriers.

Significance International trade affects global air pollution and transport by redistributing emissions related to production of goods and services and by potentially altering the total amount of global emissions. Here we analyze the trade influences by combining an economic-emission analysis on China’s bilateral trade and atmospheric chemical transport modeling. Our focused analysis on US air quality shows that Chinese air pollution related to production for exports contributes, at a maximum on a daily basis, 12–24% of sulfate pollution over the western United States. The US outsourcing of manufacturing to China might have reduced air quality in the western United States with an improvement in the east, due to the combined effects of changes in emissions and atmospheric transport.