No abstract

A haze episode occurred on 12 September 2009 in Shanghai, when the mass ratio of PM 1.0 /PM 2.5 (PM: particulate matter) reached 0.8. A similar variation of hygroscopic growth factor distribution was observed for Aitken mode particles and accumulation mode particles, implying that the enhancement of fine particles was caused by local atmospheric processing. The hygroscopicity measurements in combination with chemical analysis provided strong support for the significant contribution of (NH 4 ) 2 SO 4 and NH 4 NO 3 to the haze episode. The molar ratio of) rose up to 0.96, coincident with the large increase in NH 3 concentration, suggesting that the available NH 3 played a vital role in the enhancement of particulate sulfate and nitrate during the haze episode.

The large-scale fabrication of high-performance on-chip micro-supercapacitors (MSCs) is the footstone for the development of next-generation miniaturized electronic devices. In practical applications, however, MSCs may suffer from a low areal energy density as well as a complicated fabrication strategy that is incompatible with semiconductor processing technology. Herein, we propose a scalable fabrication strategy for the realization of a silicon-based three-dimensional (3D) all-solid-state MSC via the combination of semiconductor-based electrode processing, chemical vapor deposition, and hydrothermal growth. The individual Si/C/MnO 2 electrode shows a maximum specific capacitance of 223.74 mF cm −2 , while the symmetric electrodes present a maximum areal energy density of 5.01 μWh cm −2 at the scan rate of 1 mV s −1 . The full 3D Si/C/MnO 2 MSC delivers a high energy density of 2.62 μWh cm −2 , at a power density of 117.82 μW cm −2 , as well as a long cycle life with capacitance retention >92% after 4000 cycles. Our proposed method enables the fabrication of 3D MSCs based on a thick silicon interdigitated electrode array, holding a great promise for the development of 3D on-chip microscale energy storage devices.

Significant amounts of ammonia, nitric acid and hydrochloric acid as ammonium particle precursors have been found in urban polluted air. In order to advance understanding the formation and dissociation of ammonium nitrate and ammonium chloride, an on-line analyzer for monitoring aerosols and gases in the ambient air was employed to measure the concentrations of sulfate, nitrate and chloride in aerosols as well as related gaseous precursors at one hour resolution. The highest levels of summed hourly-averaged sulfate, nitrate, chloride and ammonium reached up to 177.7 μg/m 3 in PM 10 from 12 to 14 June, and 101.2 μg/m 3 in PM 2.5 from 1 to 3 July, 2009 in Shanghai. Ammonium nitrate and ammonium chloride were popular in aerosols with a strong linear correlation between non-sulfate ammonium (ns-NH 4 + ) and nitrate (or nitrate plus chloride). Ammonium equivalent concentration was always less than the sum of sulfate, nitrate and chloride due to ammonium-poor aerosols, whereas the atmosphere was ammonia-rich in gas phase. The ratio of gaseous nitric acid to total nitrate less than that of hydrochloric acid to total chloride both in PM 10 and PM 2.5 indicated that ammonium nitrate was more favored to be formed than ammonium chloride.

The combination of gene therapy and chemotherapy has recently received considerable attention for cancer treatment. However, low transfection efficiency and poor endosomal escape of genes from nanocarriers strongly limit the success of the clinical use of small interfering RNA (siRNA). In this study, a novel pH-responsive, surface-modified single-walled carbon nanotube (SWCNT) was designed for the codelivery of doxorubicin (DOX) and survivin siRNA. Polyethylenimine (PEI) was covalently conjugated with betaine, and the resulting PEI–betaine (PB) was further synthesized with the oxidized SWCNT to form SWCNT–PB (SPB), which exhibits an excellent pH-responsive lysosomal escape of siRNA. SPB was modified with the targeting and penetrating peptide BR2 (SPBB), thereby achieving considerably higher uptake of siRNA than SWCNT-PEI (SP) or SPB. Furthermore, SPBB–siRNA presented substantially lower survivin expression and higher apoptotic index than Lipofectamine 2000. DOX and survivin siRNA were adsorbed onto SPB to form DOX–SPBB–siRNA, and siRNA/DOX was released into the cytoplasm and nuclei of adenocarcinomic human alveolar basal epithelial (A549) cells without lysosomal retention. Compared with SPBB–siRNA or DOX–SPBB treatment alone, DOX–SPBB–siRNA significantly reduced tumor volume in A549 cell-bearing nude mice, demonstrating the synergistic effects of DOX and survivin siRNA. Pathological analysis also indicated the potential therapeutic effects of DOX–SPBB–siRNA on tumors without distinct damages to normal tissues. In conclusion, the novel functionalized SWCNT loaded with DOX and survivin siRNA was successfully synthesized, and the nanocomplex exhibited effective antitumor effects both in vitro and in vivo, thereby providing an alternative strategy for the codelivery of antitumor drugs and genes.