Nanjing University

About: Nanjing University is a education organization based out in Nanjing, China. It is known for research contribution in the topics: Catalysis & Population. The organization has 85961 authors who have published 105504 publications receiving 2289036 citations. The organization is also known as: NJU & Nanking University.

Z-Scheme Photocatalytic Systems for Promoting Photocatalytic Performance: Recent Progress and Future Challenges

Abstract: Semiconductor photocatalysts have attracted increased attention due to their great potential for solving energy and environmental problems. The formation of Z-scheme photocatalytic systems that mimic natural photosynthesis is a promising strategy to improve photocatalytic activity that is superior to single component photocatalysts. The connection between photosystem I (PS I) and photosystem II (PS II) are crucial for constructing efficient Z-scheme photocatalytic systems using two photocatalysts (PS I and PS II). The present review concisely summarizes and highlights recent state-of-the-art accomplishments of Z-scheme photocatalytic systems with diverse connection modes, including i) with shuttle redox mediators, ii) without electron mediators, and iii) with solid-state electron mediators, which effectively increase visible-light absorption, promote the separation and transportation of photoinduced charge carriers, and thus enhance the photocatalytic efficiency. The challenges and prospects for future development of Z-scheme photocatalytic systems are also presented.

A Distributed Control Strategy Based on DC Bus Signaling for Modular Photovoltaic Generation Systems With Battery Energy Storage

Abstract: Modular generation system, which consists of modular power conditioning converters, is an effective solution to integrate renewable energy sources with conventional utility grid to improve reliability and efficiency, especially for photovoltaic generation. A distributed control strategy based on improved dc bus signaling is proposed for a modular photovoltaic (PV) generation system with battery energy storage elements. In this paper, the modular PV generation system is composed of three modular dc/dc converters for PV arrays, two grid-connected dc/ac converters, and one dc/dc converter for battery charging/discharging and local loads, which is available of either grid-connected operation or islanding operation. By using the proposed control strategy, the operations of a modular PV generation system are categorized into four modes: islanding with battery discharging, grid-connected rectification, grid-connected inversion, and islanding with constant voltage (CV) generation. The power balance of the system under extreme conditions such as the islanding operation with a full-charged battery is taken into account in this control strategy. The dc bus voltage level is employed as an information carrier to distinguish different modes and determine mode switching. Control methods of modular dc/dc converters, battery converter, and grid-connected converter are addressed. An autonomous control method for modular dc/dc converters is proposed to realize smooth switching between CV operation and maximum power point tracking operation, which enables the dc bus voltage regulation capability of modular dc/dc converters. Seamless switching of a battery converter between charging and discharging and that of a grid-connected converter between rectification and inversion are ensured by the proposed control methods. Experiments verify the practical feasibility and the effectiveness of the proposed control strategies.

Sclerostin Mediates Bone Response to Mechanical Unloading Through Antagonizing Wnt/β‐Catenin Signaling

Abstract: Reduced mechanical stress leads to bone loss, as evidenced by disuse osteoporosis in bedridden patients and astronauts. Osteocytes have been identified as major cells responsible for mechanotransduction; however, the mechanism underlying the response of bone to mechanical unloading remains poorly understood. In this study, we found that mechanical unloading of wildtype mice caused decrease of Wnt/beta-catenin signaling activity accompanied by upregulation of Sost. To further analyze the causal relationship among these events, Sost gene targeting mice were generated. We showed that sclerostin selectively inhibited Wnt/beta-catenin in vivo, and sclerostin suppressed the activity of osteoblast and viability of osteoblasts and osteocytes. Interestingly, Sost(-/-) mice were resistant to mechanical unloading-induced bone loss. Reduction in bone formation in response to unloading was also abrogated in the mutant mice. Moreover, in contrast to wildtype mice, Wnt/beta-catenin signaling was not altered by unloading in Sost(-/-) mice. Those data implied that sclerostin played an essential role in mediating bone response to mechanical unloading, likely through Wnt/beta-catenin signaling. Our findings also indicated sclerostin is a promising target for preventing disuse osteoporosis.

Nanostructured conductive polypyrrole hydrogels as high-performance, flexible supercapacitor electrodes

Abstract: Electrochemically active conducting polymers are an important class of materials for applications in energy storage devices such as batteries and supercapacitors, owing to their advantageous features of unique three-dimensional (3D) porous microstructure, high capacitive energy density, scalable synthesis and light weight. Here, we synthesized a nanostructured conductive polypyrrole (PPy) hydrogel via an interfacial polymerization method. The simple synthesis chemistry offers the conductive hydrogel tunable nanostructures and electrochemical performance, as well as scalable processability. Moreover, the unique 3D porous nanostructure constructed by interconnected polymer nanospheres endows PPy hydrogels with good mechanical properties and high performance acting as supercapacitor electrodes with a specific capacitance of ∼380 F g−1, excellent rate capability, and areal capacitance as high as ∼6.4 F cm−2 at a mass loading of 20 mg cm−2.