Spin-dependent transport properties of zigzag phosphorene nanoribbons with oxygen-saturated edges.

We investigate the electronic structures and electronic transport properties of zigzag phosphorene nanoribbons with oxygen-saturated edges (O-zPNRs) by using the spin-polarized density functional theory and the nonequilibrium Green's function method. The results show that the O-zPNR is an antiferromagnetic (AFM) or ferromagnetic (FM) semiconductor with spins localized at two ribbon edges anti-parallel or parallel with each other. The electronic transmission for the single AFM or FM O-zPNR is zero when a bias voltage is applied to the two electrodes made of the same type O-zPNR. Nonzero transmission arises for the AFM-AFM and FM-FM O-zPNR heterojunctions. The transmission spectrum and the electrical current are fully spin polarized for the FM-FM O-zPNR heterojunction. An in-plane transverse electrical field can effectively manipulate the electronic structure and spin-dependent electronic transport. It induces splitting of the spins of the two edges and makes the AFM O-zPNR become a half metal. Moreover, the transverse electrical field gives rise to the transmission spectrum and the spin polarized electrical current for the AFM-AFM O-zPNR heterojunction. The degree of spin polarization can be tuned by the strength of the transverse field.

Epigallocatechin gallate inhibits human tongue carcinoma cells via HK2­mediated glycolysis.

Epigallocatechin gallate (EGCG), one of the major catechins found in green tea, was suggested to play a role as a chemopreventive agent in various human cancer models. In this study, we reported that EGCG has a profound antitumor effect on human tongue carcinoma cells by directly regulating glycolysis. EGCG dose-dependently inhibited anchorage-independent growth and short-term EGCG exposure substantially decreased EGF-induced EGF receptor (EGFR), Akt and ERK1/2 activation, as well as the downregulation of hexokinase 2 (HK2). Furthermore, inhibition of EGCG­mediated HK2 expression was involved in Akt, but not in ERK1/2 signaling pathway suppression. Overexpression of constitutively activated Akt1 rescued inhibition of EGCG­induced glycolysis. Moreover, EGCG inhibited HK2 expression on mitochondrial outer membrane and induced apoptosis. In summary, the results suggested that EGCG or a related analogue, may have a role in the management of human tongue carcinoma.

[Advance in the study of the powdered weathering profile of sandstone on China Yungang Grottoes based on VIS/NIR hyperspectral imaging].

Yungang Grottoes were built in the mid-5th century A. D., and named as a UNESCO World Heritage site in 2001. Most of the grottoes were built on the feldspathic quartz sandstones. They were seriously damaged due to the environmental impact. The main form of the weathering is the powdered weathering. The weathering conditions are generally characterized by electrical sounding, penetration resistance, molecular spectroscopy, etc. However, although these methods can give good results about the weathering conditions for a specified sample or site, they are not suitable for providing a global profile of the weathering conditions. The present paper provides a method for effectively and roundly assessing the overall powdered weathering conditions of the Yungang Grottoes based on hyperspectral imaging. Powdered weathering could change the structure and granularity of the sandstone, and thus change the spectral reflectance of the sandstone surface. Based on the hyperspectral data collected from 400 nm to 1 000 nm and normalized by log residuals method, the powdered weathering conditions of the sandstones were classified into strong weathering and weak weathering. The weathering profile was also mapped in the Envi platform. The mapping images were verified using the measured hyperspectal data of the columns in front of the 9th and 10th grottoes as the examples. The mapping images were substantially fitted to the real observations, showing that hyperspectral imaging can be used to estimate the overall powdered weathering of the sandstones.

Effect of poly (ethylene glycol) on coarsening dynamics of titanium dioxide nanocrystallites in hydrothermal reaction and the application in dye sensitized solar cells.

Titanium dioxide sols were synthesized by hydrothermal reactions with addition of poly (ethylene glycol) (Mw=20,000). Using techniques of X-ray diffraction, transmission electron microscopy, dynamic light scattering, and scanning electron microscopy, effect of PEG on the crystallographic properties, particle size, aggregating behavior, and the morphological properties of nanoparticles in the sols were studied. It was found that growth of anatase nanocrystallites was retarded by PEG. Average crystallite size of anatase nanocrystallites first decreased from 20.7 nm to 10.5 nm as the polymer concentration increased from 1 g/L to 3 g/L, and then changed little. Meanwhile, small amount of rutile phases like rutile nanowires, twin crystallites, and the "flowers" appeared continuously when the concentration increased from 3 g/L to 5 g/L. Mono-dispersion was obtained with relatively lower PEG concentration. The observed evolvement was discussed based on the interaction between the polymers and the nanocrystallites with assistance of FTIR. The coverage of polymer chains on surface of nanocrystallites leads to isolated reactors, which benefits the uniform coarsening rate of the nanocrystallites. The synthesized TiO(2) sols were utilized in dye sensitized solar cells. Performance parameters of the solar cells were discussed with assistance of dye desorption experiments. The improved dispersion in sols was found to benefit the photovoltaic performance of the cells.