Observation of the origin of d0 magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques.

Efforts have been made to elucidate the origin of d(0) magnetism in ZnO nanocactuses (NCs) and nanowires (NWs) using X-ray-based microscopic and spectroscopic techniques. The photoluminescence and O K-edge and Zn L3,2-edge X-ray-excited optical luminescence spectra showed that ZnO NCs contain more defects than NWs do and that in ZnO NCs, more defects are present at the O sites than at the Zn sites. Specifically, the results of O K-edge scanning transmission X-ray microscopy (STXM) and the corresponding X-ray-absorption near-edge structure (XANES) spectroscopy demonstrated that the impurity (non-stoichiometric) region in ZnO NCs contains a greater defect population than the thick region. The intensity of O K-edge STXM-XANES in the impurity region is more predominant in ZnO NCs than in NWs. The increase in the unoccupied (occupied) density of states at/above (at/below) the conduction-band minimum (valence-band maximum) or the Fermi level is related to the population of defects at the O sites, as revealed by comparing the ZnO NCs to the NWs. The results of O K-edge and Zn L3,2-edge X-ray magnetic circular dichroism demonstrated that the origin of magnetization is attributable to the O 2p orbitals rather than the Zn d orbitals. Further, the local density approximation (LDA) + U verified that vacancies in the form of dangling or unpaired 2p states (due to Zn vacancies) induced a significant local spin moment in the nearest-neighboring O atoms to the defect center, which was determined from the uneven local spin density by analyzing the partial density of states of O 2p in ZnO.

Entropy production and equilibration in Yang-Mills quantum mechanics.

The Husimi distribution provides for a coarse-grained representation of the phase-space distribution of a quantum system, which may be used to track the growth of entropy of the system. We present a general and systematic method of solving the Husimi equation of motion for an isolated quantum system, and we construct a coarse-grained Hamiltonian whose expectation value is exactly conserved. As an application, we numerically solve the Husimi equation of motion for two-dimensional Yang-Mills quantum mechanics (the x-y model) and calculate the time evolution of the coarse-grained entropy of a highly excited state. We show that the coarse-grained entropy saturates to a value that coincides with the microcanonical entropy corresponding to the energy of the system.

Fabrication and evaluation of a new composite composed of tricalcium phosphate, gelatin, and Chinese medicine as a bone substitute.

This study investigates the biological effects of traditional Chinese medicines on the activities of bone cells using rat bone cells. Then, a mixture of a GGT composite, that is, a novel biodegradable composite containing genipin crosslinked gelatin and tricalcium phosphate, and traditional Chinese medicine (TCM) was prepared as a GGT-TCM composite. A cultured neonatal rat calvarias organ was used to measure the potential of GGT-TCM composite for use in promoting the regeneration of defective bone tissue. The mitochondria activity of the bone cells following exposure to various concentrations of crude extracts of five herbal Chinese medicines was measured by colorimetric assay. Biochemical markers, such as alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) titers were analyzed to evaluate the activities of bone cells. Finally, we examined the organ culture units, which were maintained in cultured medium for 5 weeks. Morphology of tissue was observed, and the quantitative evaluation of the regenerated bone was determined. In a bone cells culture experiment, adding Cuscuta chinensis Lam. (TCM-5) to the bone cells culture clearly promoted the proliferation and differentiation of the osteoblasts from their precursor cells; but the reduced amount of TRAP indicated that the medicine significantly inhibited the osteoclasts activities. Opposite bone cell responses were observed when Loranthus parasiticus Merr. (TCM-3) and Achyranthes bidentata Bl. (TCM-4) were added to the bone cells culture. Eucommia ulmoides Oliv. (TCM-1) and Dipsacus asper Wall. (TCM-2) potentially influence the proliferation and differentiation of the osteoblasts from their precursor cells, but they did not affect the osteoclasts activities. The finding from the organ culture indicated that Chinese medicine effectively increased the rate of tissue regeneration of damaged bones.