High efficiency organic-inorganic hybrid perovskite solar cells have attracted significant attention and experienced a rapid development in recent years. Lithium-doped spiro-OMeTAD is one of the most commonly used hole transporting material, however, the hygroscopicity of lithium dopant usually causes serious moisture instability of devices. Herein, we demonstrate a dopant-free spiro-OMeTAD as hole transporting layer to improve the ambient stability of planar perovskite solar cells. With the optimization of the thickness of spiro-OMeTAD layer, the dopant-free spiro-OMeTAD based device achieved a comparable device performance with a champion power conversion efficiency of 16.92%. Moreover, the unencapsulated dopant-free device showed significantly improved stability, which still maintained 95% of its initial efficiency after storage in ambient environment for 60 days. This work provides a simple and valid approach to overcome the instability issue of spiro-OMeTAD based devices, paving a way to manufacture more stable and efficient perovskite photovoltaics.
The Three Gorges Dam (TGD) has altered downstream flow–sediment regimes and led to significant changes in the morphodynamic processes in the Middle Yangtze River (MYR). However, due to the complexity of this large river, the driving forces and implication of the morphodynamic processes remain insufficiently understood. This study selected two typical meandering and bar-braided reaches, the Zhicheng (ZC) and Shashi (SS) reach, to examine their responses to the TGD operation. The results showed that in the post-dam period significant channel erosion occurred with a higher erosion rate in the ZC reach (closer to the TGD) compared with the SS reach. The area of the Guanzhou mid-channel bar (ZC reach) and the Sanba mid-channel bar (SS reach) shrank by 30 and 90% from 2003 to 2015, respectively. The increased fluvial erosion intensity due to the reduction in suspended sediment concentration (SSC) drove the shrinkage of the mid-channel bars, as demonstrated by empirical relationships between bar geometry and fluvial erosion intensity. An increase of 22 days per year in the frequency of post-dam medium-to-high discharges (10 000–25 000 m3 s−1), and associated with the reduction in SSC, jointly led to the greater erosion at the convex (inner) banks than the concave (outer) banks, which has negatively affected the designed navigation channels at the concave banks by decreasing their discharge partitioning ratios. The post-dam water level at a given high discharge (>25 000 m3 s−1) showed no evident change, but the water level at a given low discharge (<10 000 m3 s−1) decreased. The reduction in water levels at low flows can affect water supply and riverine ecosystems in the MYR.
The merged droplets have great practical application value in protein synthesis and crystallization. In this paper, the effect of geometry configuration on the merged droplet formation in a double T-junction microchannel is studied by three-dimensional numerical simulation using the level-set method. There are three important parameters in the geometry configuration of the microchannel, namely angle between two phases (alpha), height-to-width ratio (Lambda= H/w(c)), and intersection width ratio (Gamma=w(d)/w(c)). In this study we found that a critical value of the two-phase angle is 60 degrees. When the angle is 60 degrees, the effective diameter of the merged droplet is the smallest and the generation frequency is the fastest under the same physical condition. We found that height-to-width ratio and intersection width ratio have a critical value of 1.0. When height-to-width ratio or intersection width ratio is 1.0, the shearing capacity of the continuous relative dispersed phase reaches a maximum, thus the droplet diameter is minimized and the frequency is the fastest. Therefore, reasonable adjustment of these three factors is an effective method to solve the problem of the high-throughput monodispersemerged droplet formation. This work lays a solid theoretical foundation for the merged droplets in practical applications.
Viruses could rapidly diversify into variants, which has long been known to facilitate viral adaption in the host. Recent studies showed that cooperation among variants and wild-type (WT) also increased viral fitness. Here, a mutant of sC69∗ in small hepatitis B surface protein (SHBs) that resulted in premature stop was investigated and the frequency of sC69∗ was 4.37% (19/435), most of which coexisted with the WT (78.95%, 15/19), indicating mixed viral populations. Functional studies showed that sC69∗ mutant was associated with lower viral spread, but could be rescued by coexisting with the WT. The sC69∗ mutant showed to attenuate host innate immune response during infection and poly (I:C) treatment such as IL29, ISG15, and RIG-I (p < 0.05). The lower immune response was not caused by the lower replication of sC69∗ mutant. Our data provide information that sC69∗ coexisting with the WT might facilitate the fitness and persistence of the viral quasispecies in the host.
Keywords: HBV; innate immune response; sC69∗; truncated mutant; viral infectivity.