We report on the fabrication and electroluminescence of an n-ZnO nanorod/p-Si heterojunction. ZnO nanorods were grown on p-type Si substrates employing an easy low-temperature aqueous solution method. As-grown ZnO nanorods showed good crystallinity and a preferable c axial orientation. Electroluminescent devices were constructed using high-molecular-weight polymers as the fill-in, and the I–V characteristics were diode-like. A typical electroluminescent spectrum of such an n-ZnO/p-Si heterojunction under forward bias was composed of a narrow ultraviolet peak centred at 387 nm and a broad green band at 535 nm, consistent with the photoluminescent spectrum. The intensity of the ultraviolet light grew more quickly than that of the green light with the increasing of bias.

By proposing a varying coefficient Susceptible-Infected-Removal model (vSIR), we track the epidemic of COVID-19 in 30 provinces in China and 15 cities in Hubei province, the epicenter of the outbreak. It is found that the spread of COVID-19 has been significantly slowing down within the two weeks from January 27 to February 10th with 87.0% and 84.3% reductions in the reproduction number R0 among the 30 provinces and 15 Hubei cities, respectively. This suggests the extreme control measures implemented since January 23, which include cutting off Wuhan and many other cities and towns, a great public awareness and high level of self isolation at home, have contributed to a substantial decline in the reproductivity of the COVID-19 in China. We predict that Hubei province will reach its peak between February 20 and 22, 2020, and if the removal rate can be increased to 0.1, the epidemic outside Hubei province will end in May 2020, and inside Hubei in early June.

In 2012 air pollutants were responsible of seven million human death worldwide, and among them particulate matter with an aerodynamic diameter of 2.5 micrometers or less (PM2.5) are the most hazardous because they are small enough to invade even the smallest airways and penetrate to the lungs. During the last decade the size, shape, composition, sources and effect of these particles on human health have been studied. However, the noxiousness of these particles not only relies on their chemical toxicity, but particle morphology and mechanical properties affect their thermodynamic behavior, which has notable impact on their biological activity. Therefore, correlating the physical, mechanical and chemical properties of PM2.5 airborne pollutants should be the first step to characterize their interaction with other bodies but, unfortunately, such analysis has never been reported before. In this work, we present the first nanomechanical characterization of the most abundant and universal groups of PM2.5 airborne pollutants and, by means of atomic force microscope (AFM) combined with other characterization tools, we observe that fluffy soot aggregates are the most sticky and unstable. Our experiments demonstrate that such particles show strong adhesiveness and aggregation, leading to a more diverse composition and compiling all possible toxic chemicals.

Carbon nanotube sponges are lightweight, conductive, highly porous, and flexible. An integration of these properties is suitable for constructing high-performance electrocapillary imbibers. Water imbibition into the sponges can be initiated at low potentials with tunable uptake rates and switched on and off reversibly. These controllable nanoporous imbibers have potential applications in a wide range of flexible micro- and nanofluidic systems.