Arsenite-Induced Alterations of DNA Photodamage Repair and Apoptosis After Solar-Simulation UVR in Mouse Keratinocytes in Vitro

Our laboratory has shown that arsenite markedly increased the cancer rate caused by solar-simulation ultraviolet radiation (UVR) in the hairless mouse skin model. In the present study, we investigated how arsenite affected DNA photodamage repair and apoptosis after solar-simulation UVR in the mouse keratinocyte cell line 291.03C. The keratinocytes were treated with different concentrations of sodium arsenite (0.0, 2.5, 5.0 μM) for 24 hr and then were immediately irradiated with a single dose of 0.30 kJ/m(2) UVR. At 24 hr after UVR, DNA photoproducts [cyclobutane pyrimidine dimers (CPDs) and 6–4 photoproducts (6-4PPs)] and apoptosis were measured using the enzyme-linked immunosorbent assay and the two-color TUNEL (terminal deoxynucleotide transferase dUTP nick end labeling) assay, respectively. The results showed that arsenite reduced the repair rate of 6-4PPs by about a factor of 2 at 5.0 μM and had no effect at 2.5 μM. UVR-induced apoptosis at 24 hr was decreased by 22.64% at 2.5 μM arsenite and by 61.90% at 5.0 μM arsenite. Arsenite decreased the UVR-induced caspase-3/7 activity in parallel with the inhibition of apoptosis. Colony survival assays of the 291.03C cells demonstrate a median lethal concentration (LC(50)) of arsenite of 0.9 μM and a median lethal dose (LD(50)) of UVR of 0.05 kJ/m(2). If the present results are applicable in vivo, inhibition of UVR-induced apoptosis may contribute to arsenite’s enhancement of UVR-induced skin carcinogenesis

A novel push-and-pull hybrid data broadcast scheme for wireless information networks

A new push-and-pull hybrid data broadcast scheme is proposed for providing wireless information services to three types of clients, general, pull and priority clients. Only pull and priority clients have the back channel for sending requests to the broadcast server. There is no scalability problem with the hybrid scheme because the amount of pull and priority clients is very small. Based on the requests collected from pull and priority clients, the server estimates the interest pattern changes of the whole client population. Then the broadcast schedule on the push channel for the next broadcast cycle is adjusted. Besides the push channel, a small amount of broadcast bandwidth is allocated to a pull channel. The data to be broadcast on the pull channel is decided by the server in real-time and priority is given to requests from priority clients. Simulations show that with a time-varying client interest pattern, the average data access time for all three types of clients can be minimized. Because of the priority in using the pull channel, priority clients can achieve the lowest access time and pull clients can achieve a lower access time than general clients. To further improve the performance, the hybrid scheme with local client cache is also investigated.published_or_final_versio

Origin Identification and Quantitative Analysis of Honeys by Nuclear Magnetic Resonance and Chemometric Techniques

The combination of H-1 NMR spectroscopy and multivariate statistical analysis has become a promising method for the discrimination of food origins. In this paper, this method has been successfully employed to analyze 70 Chinese honey samples from eight botanic origins, three geographical origins, and five production dates. Thirty-three components in honey samples were detected and identified from their H-1 NMR spectra, and 20 of them were accurately quantified by comparing their integral area with that of internal standards with relaxation time correction. Nontargeted principal component analysis (PCA) has been applied to distinguish the honeys from different botanical and geographical origins. The variations of components in the honeys, including saccharides and all kind of amino and organic carboxylic acids, confirmed their clustering according to their origins in PCA scores plots. Orthogonal partial least squares discriminant analysis (OPLS-DA) based on the NMR data for the different pairwise honey samples allows to identify the compositional variations contributed to geographical discrimination and storage time. Hence, NMR spectroscopy coupled with chemometric techniques offers an efficient tool for quality control of honey, and it could further serve to the classification, qualitative and quantitative control of other foods

Lie Detection using functional MRI

published_or_final_versio

Joint actions with large partners and small-firm ambidexterity in asymmetric alliances:The mediating role of relational identification

This study investigates the role of relational identification in the relation between joint actions and small-firm ambidexterity in asymmetric alliances. Using survey data on Chinese high-technology firms, we find that joint problem-solving and joint sensemaking are both positively associated with small firm's relational identification. We also find a positive relationship between small firm's relational identification and knowledge exploration and exploitation. More importantly, we show that relational identification mediates the relationships between joint actions (i.e., joint problem-solving and joint sensemaking) and small-firm ambidexterity, except for the relationship between joint sensemaking and small-firm knowledge exploitation. This study advances our understanding of the association between joint actions and ambidexterity by providing a social identification explanation

The effect of immobilization process to the activity of mthase and mtsase

2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Understanding the luminescent nature of organic radicals for efficient doublet emitters and pure-red light-emitting diodes.

The doublet-spin nature of radical emitters is advantageous for applications in organic light-emitting diodes, as it avoids the formation of triplet excitons that limit the electroluminescence efficiency of non-radical emitters. However, radicals generally show low optical absorption and photoluminescence yields. Here we explain the poor optical properties of radicals based on alternant hydrocarbons, and establish design rules to increase the absorption and luminescence yields for donor-acceptor-type radicals. We show that non-alternant systems are necessary to lift the degeneracy of the lowest energy orbital excitations; moreover, intensity borrowing from an intense high-lying transition by the low-energy charge-transfer excitation enhances the oscillator strength of the emitter. We apply these rules to design tris(2,4,6-trichlorophenyl)methyl-pyridoindolyl derivatives with a high photoluminescence quantum yield (>90%). Organic light-emitting diodes based on these molecules showed a pure-red emission with an over 12% external quantum efficiency. These insights may be beneficial for the rational design and discovery of highly luminescent doublet emitters

The spectra of lifted digraphs

We present a method to derive the complete spectrum of the lift \mathrm{\Gamma\alpha} of a base digraph \mathrm{\Gamma}, with voltage assignment α on a (finite) group $\textit{G}$. The method is based on assigning to \mathrm{\Gamma} a quotient-like matrix whose entries are elements of the group algebra \mathds{C}[$\textit{G}$], which fully represents \mathrm{\Gamma\alpha}. This allows us to derive the eigenvectors and eigenvalues of the lift in terms of those of the base digraph and the irreducible characters of G. Thus, our main theorem generalizes some previous results of Lovász and Babai concerning the spectra of Cayley digraphs