Xiaoyue Xu

© 2016 American Chemical Society.Layered transition metal chalcogenides with large spin orbit coupling have recently sparked much interest due to their potential applications for electronic, optoelectronic, spintronics, and valleytronics. However, most current understanding of the electronic structure near band valleys in momentum space is based on either theoretical investigations or optical measurements, leaving the detailed band structure elusive. For example, the exact position of the conduction band valley of bulk MoS2 remains controversial. Here, using angle-resolved photoemission spectroscopy with submicron spatial resolution, we systematically imaged the conduction/valence band structure evolution across representative chalcogenides MoS2, WS2, and WSe2, as well as the thickness dependent electronic structure from bulk to the monolayer limit. These results establish a solid basis to understand the underlying valley physics of these materials, and also provide a link between chalcogenide electronic band structure and their physical properties for potential valleytronics applications.

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimAll transparent conducting materials of technological practicality are n-type; the inferior conductivity of p-type TCMs has limited their adoption. In addition, many relatively high-performing p-type TCMs require synthesis temperatures >400 °C. Here, room-temperature pulsed laser deposition of copper-alloyed zinc sulfide thin films is reported. For 0.09 ≤ x ≤ 0.35, CuxZn1-xS has high p-type conductivity, up to 42 S cm−1 at x = 0.30, with an optical band gap tunable from ≈3.0–3.3 eV and transparency, averaged over the visible, of 50%–71% for 200–250 nm thick films. In this range, synchrotron X-ray and electron diffraction reveal a nanocrystalline ZnS structure. Secondary crystalline CuyS phases are not observed, and at higher Cu concentrations, x > 0.45, films are amorphous and poorly conducting. Within the TCM regime, the conductivity is temperature independent, indicating degenerate hole conduction. A decrease in lattice parameter with Cu content suggests that the hole conduction is due to substitutional incorporation of Cu onto Zn sites. This hole-conducting phase is embedded in a less conducting amorphous CuyS, which dominates at higher Cu concentrations. The combination of high hole conductivity and optical transparency for the peak conductivity CuxZn1-xS films is among the best reported to date for a room temperature deposited p-type TCM.

ABSTRACT: Magnetic fusion is a long-term solution for producing electrical power for the world, and the large thermonuclear international device being constructed will produce net energy and a path to fusion energy provided the computer modeling is accurate. To effectively address the requirements of the high-end fusion simulation community, application developers, algorithm designers, and hardware architects must have reliable simulation data gathered at scale for scientifically valid configurations. This paper presents detailed benchmarking results for a set of magnetic fusion applications with a wide variety of underlying mathematical models including both particle-in-cell and Eulerian codes using both implicit and explicit numerical solvers. Our evaluation on a petascale Cray XE6 platform focuses on profiling these simulations at scale identifying critical performance characteristics, including scalability, memory/network bandwidth limitations, and communication overhead. Overall results are a key in improving fusion code design, and are a critical first step towards exascale hardware-software co-design — a process that tightly couples applications, algorithms, imple- mentation, and computer architecture.

Injury to the central or peripheral nervous system is often associated with persistent pain. After ischemic injury to the spinal cord, rats develop severe mechanical allodynia-like symptoms, expressed as a pain-like response to innocuous stimuli. In its short-lasting phase the allodynia can be relieved with the [gamma]-aminobutyric acid (GABA)-B receptor agonist baclofen, which also reverses the hyperexcitability of dorsal horn interneurons to mechanical stimuli. Furthermore, there is a reduction in GABA immunoreactivity in the dorsal horn of allodynic rats. Clinical neuropathic pain of peripheral and central origin often cannot be relieved by opiates at doses that do not cause side effects. The loss of sensitivity to opiates may be associated with the up-regulation of endogenous antiopioid substances, such as the neuropeptide cholecystokinin (CCK). CCK and its receptor (CCK-R) protein is normally not detectable in rat dorsal root ganglion cells. After peripheral nerve section, both CCK and CCK-R are up-regulated in the dorsal root ganglia. Furthermore, CI 988, an antagonist of the CCK-B receptor, chronically coadministered with morphine, reduces autotomy, a behavior that may be a sign of neuropathic pain following peripheral nerve section. Thus, opiate insensitivity may be due to the release of CCK from injured primary afferents. Similarly, in the chronic phase of the spinal ischemic model of central pain, the allodynia-like symptom is not relieved by systemic morphine, but is significantly reversed by the CCK-B antagonist. Consequently, up-regulation of CCK and CCK-R in the CNS may also underlie opiate drug insensitivity following CNS injury. Thus, dysfunction of central inhibition involving GABA and endogenous opioids may be a factor underlying the development of sensory abnormalities and/or pain following injury to neural tissue

Based on the institutional theory, this article attempts to examine two consecutive questions regarding the impact of various factors on corporate decision in environmental information disclosure (EID): (1) whether or not to disclose; and (2) the level of disclosure. The relevance of these factors is empirically tested using data collected from publicly listed manufacturing companies from 2006 to 2008 in China. Some interesting findings appear. We find that firms that are state-owned, those that operate in environmentally sensitive industries, those having more industrial peers engaged in EID, and those with better reputation are more likely to disclose environmental information. When it comes to the content of EID, variables that attempt to capture external institutional pressures exhibit either no or weak explanatory power. Only the variable of organizational image and reputation is demonstrated to have a significant impact on both the act and the content of EID. This study provides a snapshot of the dialogues between constituencies in the organizational field and EID development.

The stock market’s reaction to information disclosure of environmental violation events (EVEs) is investigated multi-dimensionally for Chinese listed companies, including variables such as pollution types, information disclosure sources, information disclosure levels, modernization levels of the region where the company locates, ultimate ownership of the company, and ownership held by the largest shareholder. Using the method of event study, daily abnormal return (AR) and accumulative abnormal return (CAR) are calculated under different event window for examining the extent to which the stock market responds to the EVEs. Furthermore, statistical significance of the difference in stock market reaction is compared between event firms with different characteristics. The relationship between CAR and its impact factors is examined by multivariate analysis. The findings reveal that the average reduction in market value is estimated to be much lower than the estimated changes in market value for similar events in other countries, demonstrating that the negative environmental events of Chinese listed companies currently have weak impact on the stock market

We have empirically examined the relationship between top executives’ turnover and the corporate environmental responsibility by identifying the influence of ten specific turnover reasons resulting in the chairman’s departure and two important types of chairman’s succession. Using a sample of 782 manufacturing listed companies across 3 years in China, we find that the corporate environmental responsibility is negatively associated with the involuntary and negative turnover (i.e., dismissal, health and death, and forced resignation) and positively associated with improving corporate governance, and not associated with the normal turnover (i.e., retirement and contract expiration) and the types of chairman’s succession (i.e., independence, and internal or external promotion). Our study significantly contributes to research in environmental disclosure by revealing the relationship between chairman’s turnover and the corporate environmental responsibility. A feasible way is suggested to regulators and other stakeholders in monitoring or assessing the possible abnormality of environmental responsibility when firms experience involuntary and negative chairman’s turnover in the emerging economies