Nanjing University

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

Avoiding Energy Holes in Wireless Sensor Networks with Nonuniform Node Distribution

Abstract: In this paper, we investigate the theoretical aspects of the nonuniform node distribution strategy used to mitigate the energy hole problem in wireless sensor networks (WSNs). We conclude that in a circular multihop sensor network (modeled as concentric coronas) with nonuniform node distribution and constant data reporting, the unbalanced energy depletion among all the nodes in the network is unavoidable. Even if the nodes in the inner coronas of the network have used up their energy simultaneously, the ones in the outermost corona may still have unused energy. This is due to the intrinsic many-to-one traffic pattern of WSNs. Nevertheless, nearly balanced energy depletion in the network is possible if the number of nodes increases in geometric progression from the outer coronas to the inner ones except the outermost one. Based on the analysis, we propose a novel nonuniform node distribution strategy to achieve nearly balanced energy depletion in the network. We regulate the number of nodes in each corona and derive the ratio between the node densities in the adjacent (i + 1)th and ith coronas by the strategy. Finally, we propose (q-switch routing, a distributed shortest path routing algorithm tailored for the proposed nonuniform node distribution strategy. Extensive simulations have been performed to validate the analysis.

Selective fluorescent probes for live-cell monitoring of sulphide

Abstract: Aqueous sulphides, including hydrogen sulphide, have important roles in biological signalling and metabolic processes. Here we develop a selective sulphide-trapping strategy involving sulphide addition to an aldehyde; the resulting hemithioacetal undergoes a Michael addition with an adjacent unsaturated acrylate ester to form a thioacetal at neutral pH in aqueous solution. Employing this new strategy, two sulphide-selective fluorescent probes, SFP-1 and SFP-2, were synthesized on the basis of two different fluorophore templates. These probes exhibit an excellent fluorescence increase and an emission maximum shift (SFP-1) in response to Na(2)S and H(2)S in a high thiol background as found under physiological conditions. We show the utility of the probes for the selective detection of sulphides, and the capacity of our probes to monitor enzymatic H(2)S biogenesis and image free sulphide in living cells.

Significant Contribution of Intrinsic Carbon Defects to Oxygen Reduction Activity

Abstract: While the field of carbon-based metal-free electrocatalysts for oxygen reduction reaction (ORR) has experienced great progress in recent years, the fundamental issue of the origin of ORR activity is far from being clarified. To date, the ORR activities of these electrocatalysts are usually attributed to different dopants, while the contribution of intrinsic carbon defects has been explored little. Herein, we report the high ORR activity of the defective carbon nanocages, which is better than that of the B-doped carbon nanotubes and comparable to that of the N-doped carbon nanostructures. Density functional theory calculations indicate that pentagon and zigzag edge defects are responsible for the high ORR activity. The mutually corroborated experimental and theoretical results reveal the significant contribution of the intrinsic carbon defects to ORR activity, which is crucial for understanding the ORR origin and exploring the advanced carbon-based metal-free electrocatalysts.

Chinese Guanxi: An integrative review and new directions for future research

Abstract: In this article we review research on Chinese guanxi and social networking in the past twenty years and identify the major perspectives, theories, and methodologies used in guanxi research at micro and macro levels. We summarize the main findings of over 200 journal articles on guanxi research in terms of its conceptual definitions and measurements, its antecedents and consequences, and its dynamics and processes. Furthermore, we identify the gaps between different levels of guanxi research and discuss future directions to advance our understanding of the complex and intricate guanxi phenomenon.

Estimating Ground-Level PM2.5 in China Using Satellite Remote Sensing

Abstract: Estimating ground-level PM2.5 from satellite-derived aerosol optical depth (AOD) using a spatial statistical model is a promising new method to evaluate the spatial and temporal characteristics of PM2.5 exposure in a large geographic region. However, studies outside North America have been limited due to the lack of ground PM2.5 measurements to calibrate the model. Taking advantage of the newly established national monitoring network, we developed a national-scale geographically weighted regression (GWR) model to estimate daily PM2.5 concentrations in China with fused satellite AOD as the primary predictor. The results showed that the meteorological and land use information can greatly improve model performance. The overall cross-validation (CV) R2 is 0.64 and root mean squared prediction error (RMSE) is 32.98 μg/m3. The mean prediction error (MPE) of the predicted annual PM2.5 is 8.28 μg/m3. Our predicted annual PM2.5 concentrations indicated that over 96% of the Chinese population lives in areas that ex...