Strength and Stability Analysis of a Single Walled Black Phosphorus Tube under Axial Compression

Few-layered black phosphorus materials recently attract much attention due to its special electronic properties. As a Consequence, the nano-tube from a single-layer black phosphorus has been theoretically built. The corresponding electronic properties of such black phosphorus nano-tube were also evaluated numerically.Comment: 12 pages,8 figures, and 33 reference

China's Land Market Auctions: Evidence of Corruption

This paper studies the urban land market in China in 2003--2007. In China, all urban land is owned by the state. Leasehold use rights for land for (re)development are sold by city governments and are a key source of city revenue. Leasehold sales are viewed as a major venue for corruption, prompting a number of reforms over the years. Reforms now require all leasehold rights be sold at public auction. There are two main types of auction: regular English auction and an unusual type which we call a "two stage auction". The latter type of auction seems more subject to corruption, and to side deals between potential bidders and the auctioneer. Absent corruption, theory suggests that two stage auctions would most likely maximize sales revenue for properties which are likely to have relatively few bidders, or are "cold", which would suggest negative selection on property unobservables into such auctions. However, if such auctions are more corruptible, that could involve positive selection as city officials divert hotter properties to a more corruptible auction form. The paper finds that, overall, sales prices are lower for two stage auctions, and there is strong evidence of positive selection. The price difference is explained primarily by the fact that two stage auctions typically have just one bidder, or no competition despite the vibrant land market in Chinese cities.

Agency cost of government ownership : a study of voluntary audit comitte formation in China

In this paper, we investigate the agency costs of government ownership and their impact on corporate governance and firm value. China is used as a laboratory because of the prevalent state shareholdings in exchange-listed firms. In this context, we specifically consider the trade-offs involved in the voluntary formation of an audit committee when the controlling shareholder is the state. The decision to improve corporate governance (in this case, introduce an audit committee) is shown to be value relevant and a function of existing agency relationships and non-trivial implementation costs. Our findings are robust to the level of pyramid groups, the ownership-control wedge, and financial leverage. The research adds to the debate regarding the effect of government shareholdings on corporate culture and performance - a topic that hastaken on renewed importance in recent times

Differences in diversity and community assembly processes between planktonic and benthic diatoms in the upper reach of the Jinsha River, China

Comparing spatio-temporal patterns between planktonic and benthic algae is helpful for understanding their associations and differences. However, such studies are still rare especially in large rivers. We used a dataset collected in the upper reach of the Jinsha River in different seasons to explore biodiversity and assembly processes of planktonic and benthic diatom assemblages. We found that planktonic and benthic diatoms presented different seasonal variation in species richness and community compositions. We also found evidence that planktonic and benthic diatoms were coupled in the summer. Planktonic diatom assemblages were mainly affected by spatial processes via directional spatial dispersal, especially in the summer. By comparison, benthic diatom assemblages were more affected by environmental processes. Our findings suggest that mass effect and species sorting paradigms explain the assembly processes of planktonic and benthic diatom assemblages, respectively, but the explanatory powers of these two paradigms vary seasonally. To effectively monitor and assess ecological conditions of large rivers, we recommend using benthic algae as a biotic indicator group as they had stronger correlations with environmental factors.Peer reviewe

Winding a nanotube from black phosphorus nanoribbon onto a CNT at low temperature: A molecular dynamics study

Black phosphorus (BP) has become a popular two dimensional semiconducting material. Investigation of a BP nanotube, theoretically and experimentally, is therefore a hot topic attracting many recent researchers. In this paper, a nanotube system is proposed by placing a BP ribbon near a carbon nanotube (CNT) to form a BP nanotube. The system is formed based on the following two aspects. The first is that the CNT has a perfect surface that provides only van der Waals attraction to the BP ribbon. The BP ribbon does not damage the CNT. The second aspect is that a BP ribbon can feature a large curvature without breaks of the phosphorus-phosphorus bonds in it. If the length of the BP ribbon is well chosen to be a ‘perfect length’, the ribbon can form a perfect BP nanotube winding on a CNT at very low temperature. At higher temperature, e.g., ≥ 50 K, it is difficult to obtain a perfect BP nanotube. With a BP ribbon whose length is greater than the perfect length, it is difficult to create a perfect BP nanotube even at ultralow temperature

Effects of Reservoir Mainstream on Longitudinal Zonation in Reservoir Bays

Spatial longitudinal zonation in reservoir bays is poorly documented, and most published papers considered that longitudinal zonation in bays is similar to that in reservoirs. Our results from analyses of the benthic macroinvertebrate community in the bays of the Three-Gorges Reservoir, China, showed that a typical bay contains four distinct zones-one more zones than a reservoir. This newly distinguished zone lies along the mouth stretch of a reservoir bay, and we call it a mainstream zone because it is disturbed by the reservoir mainstream. The mainstream zone is characterized by a lower standing crop and a more unstable macroinvertebrate community than in the lacustrine zone. Longitudinal zonation of reservoir bays is related to their lengths, and lacustrine zones develop only where the bay is sufficiently long. Similar to reservoirs, longitudinal zonation in bays is also dynamic and is to some extent influenced by the ages of bays and seasons