Emission bands of nitrogen-implantation induced luminescent centers in ZnO crystals: experiment and theory

High quality ZnO crystals with the sharp band-edge excitonic emission and very weak green emission were implanted by nitrogen ions. An additional red emission band was observed in the as-implanted ZnO crystal and investigated as a function of temperature. By employing the underdamped multimode Brownian oscillator model for the general electron-phonon coupling system, both the original green and nitrogen-implantation induced red emission bands were theoretically reproduced at different temperatures. Excellent agreement between the theory and the experiment enables us determine the energetic positions of the pure electronic levels associated with the green and red emission bands, respectively. The determined energy level of the red emission band is in good agreement with the data obtained from the deep-level transient spectroscopy measurements. © 2012 American Institute of Physics.published_or_final_versio

Inactivation of hypoxia inducible factor (HIF) 1 alpha induces obesity-associated metabolic disorders through brown adipose tissue dysfunction

published_or_final_versionThe 14th Medical Research Conference, Hong Kong, 10 January 2009. In Hong Kong Medical Journal, 2009, v. 15, suppl. 1, p. 40, article no. 6

Abnormal gas pressure sensitivity of the visible emission in ZnO quantum dots prepared by improved sol-gel method: the role of surface polarity

published_or_final_versio

PIKfyve, a class III lipid kinase, is required for TLR-induced type I IFN production via modulation of ATF3

Type I IFN plays a key role in antiviral responses. It also has been shown that deregulation of type I IFN expression following abnormal activation of TLRs contributes to the pathogenesis of systemic lupus erythematosus. In this study, we find that PIKfyve, a class III lipid kinase, is required for endolysosomal TLR-induced expression of type I IFN in mouse and human cells. PIKfyve binds to phosphatidylinositol 3-phosphate and synthesizes phosphatidylinositol 3,5-bisphosphate, and plays a critical role in endolysosomal trafficking. However, PIKfyve modulates type I IFN production via mechanisms independent of receptor and ligand trafficking in endolysosomes. Instead, pharmacological or genetic inactivation of PIKfyve rapidly induces expression of the transcription repressor ATF3, which is necessary and sufficient for suppression of type I IFN expression by bin'ding to its promoter and blocking its transcription. Thus, we have uncovered a novel phosphoinositide-mediated regulatory mechanism that controls TLR-mediated induction of type I IFN, which may provide a new therapeutic indication for the PIKfyve inhibitor.X111313Ysciescopu

Molecular characterisation of canine parvovirus strains circulating in China

Canine parvovirus (CPV) was first isolated at 1978 in the USA. Analysis of CPV isolates by monoclonal antibodies and restriction enzymes have shown that after the first emergence of CPV (CPV-2) it evolved to give rise to new antigenic types, which were designated CPV types 2a, 2b and 2c. These new types have replaced the original CPV type 2, although the proportions of each of the new antigenic types vary in different countries. In China, CPV infections were first observed in 1982, however, there has been no information concerning the antigenic types of CPV prevailing in China now. In this study, we designed a PCR assay to type canine parvovirus strains in fecal samples collected from symptomatic dogs from 2006 to 2009. Our data showed that the CPV prevalent strain is mostly 2b, the proportion of CPV-2a is very low, no CPV-2c and CPV-2 were observed

A 60-year record of 129I in Taal Lake sediments (Philippines): Influenceof human nuclear activities at low latitude region

The influence of human nuclear activities on environmental radioactivity is not well known at low latitude regions that are distant from nuclear test sites and nuclear facilities. A sediment core collected from Taal Lake in the central Philippines was analyzed for 129I and 127I to investigate this influence in a low-latitude terrestrial system. A baseline of 129I/127I atomic ratios was established at (2.04e5.14) * 10-12&nbsp;in the pre-nuclear era in this region. Controlled by the northeasterly equatorial trade winds, increased 129I/127I ratios of (20.1e69.3) * 10-12 suggest that atmospheric nuclear weapons tests at the Pacific Proving Grounds in the central Pacific Ocean was the major source of 129I in the sediment during 1956-1962. The 129I/127I ratios, up to 157.5*10-12 after 1964, indicate a strong influence by European nuclear fuel reprocessing plants. The East Asian Winter Monsoon is found to be the dominant driving force in the atmospheric dispersion of radioactive iodine (129I) from the European nuclear fuel reprocessing plants to Southeast Asia, which is also important for dispersion of other airborne pollutants from the middle-high to low latitude regions. A significant 129I/127I peak at 42.8 cm in the Taal Lake core appears to be the signal of the Chernobyl accident in 1986. In addition, volcanic activities are reflected in the iodine isotope profiles in the sediment core, suggesting the potential of using iodine isotopes as an indicator of volcanic eruptions.<br style="line-height: normal; text-align: -webkit-auto; text-size-adjust: auto;" /

Wireless sensor monitoring of Paddington Station Box Corner

This paper presents the real performance of three diaphragm wall panels on the southeast corner of Paddington Station Box during excavation, monitored using a wireless sensor network. In total, 15 LPDT displacement sensors, 12 tilt sensors, 13 relay nodes and a gateway were deployed at three different stages. Each wireless sensor node is programmed with Contiki OS using the in-built IPv6-based network layer (6LoWPAN/RPL) for link-local addressing and routing, and ContikiMAC at the medium access control (MAC) layer for radio duty cycling. Extensive testing and calibration was carried out in the laboratory to ensure that the system functioned as expected. Wireless tilt and displacement sensors were installed to measure the inclination, angular distortion and relative displacement of these corner panels at three different depths. The monitoring data reveal that the corner produced a stiffening effect on the station box, which might result in a breakdown of plane strain conditions. The network performance characteristics (e.g. message reception ratio and network topology status) and challenges are also highlighted and discussed

SHMS-based fatigue reliability analysis of multiloading suspension bridges

Author name used in this manuscript: Z. W. Chen2011-2012 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

Computerized characterization of the yarn snarling distribution

2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Probing deep level centers in GaN epilayers with variable-frequency capacitance-voltage characteristics of AuGaN Schottky contacts

Under identical preparation conditions, AuGaN Schottky contacts were prepared on two kinds of GaN epilayers with significantly different background electron concentrations and mobility as well as yellow emission intensities. Current-voltage (I-V) and variable-frequency capacitance-voltage (C-V) characteristics show that the Schottky contacts on the GaN epilayer with a higher background carrier concentration and strong yellow emission exhibit anomalous reverse-bias I-V and C-V characteristics. This is attributed to the presence of deep level centers. Theoretical simulation of the low-frequency C-V curves leads to a determination of the density and energy level position of the deep centers. © 2006 American Institute of Physics.published_or_final_versio