BAD (Phospho-Ser112) ELISA Kit

The counter electrode (CE) plays an important role in determining the overall performance of quantum dots (QDs) sensitized solar cells (QDSCs) by collecting the electrons from the external circuit and catalyzing the reduction of oxidized electrolyte. Metal sulfides/selenides have been commonly used as CE in QDSCs. Among these CEs, the copper selenides are considered to be a superior CE for realizing highly efficient QDSCs due to its excellent catalytic activity. However, there has always been a trade-off between catalytic activity and conductivity in copper selenides CEs, such as the CE based on copper selenide nanoparticles has highest specific surface areas, leading to best catalytic activity compared with the CEs based on other copper selenide nanostructures (nanowires, nanorods, nanosheets etc.). But it also faces the worst conductivity due to a large number of grain boundaries existed in the copper selenide film based on nanoparticles. In this work, graphene (GR)/Cu2-xSe composite material has been prepared via a facile hot injection method, and their photovoltaic and electrochemical properties are studied in detail. Through optimizing the ratio of GR:Cu2-xSe and sintering temperature, the QDSCs based on the optimized GR/Cu2-xSe composite CE shows an obvious improvement in cell performances and yield a PCE of 6.66% compared with that of the cells based on bare Cu2-xSe (5.95%), bare Graphene (2.82%) and bare CuxS (4.85%) CEs. The improved performance of the composite CE was attributed to the combining effect of high catalytic activity of Cu2-xSe nanoparticles and good conductivity of graphene. This work demonstrates that GR/Cu2-xSe composite CE could be potential candidate for realizing high efficiency QDSCs. (C) 2020 Elsevier B.V. All rights reserved.

The forward recurrence time (also known as residual or excess lifetime) is one of the key quantities in renewal theory. The study of the variability of the forward recurrence time (as measured by the variance or the standard deviation) is important especially when we want to predict when the next event will occur. In this paper we study the moments of the forward recurrence time in a renewal process. In particular, we discuss the monotonicity of the variance for these recurrence times and study the covariance between the forward recurrence time at t and the number of renewals over [0,t]. The forward recurrence time practically applies in a number of cases. For example, in preventive replacement within any production process the forward recurrence time is the remaining time of the component. In medicine, for a chronic disease observed from one point onwards, the forward recurrence time is defined as the time in disease state until healing.