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The development of cloud storage makes people willing to upload personal video to the cloud,but the data security problems brought by it have become increasingly prominent,selective encryption is one of the effective ways to protect video privacy.Aiming at the problem of insufficient security in the current H.264/AVC video selective encryption method,a novel H.264/AVC video selective encryption method based on adaptive permutation of macroblock coding information is proposed.The method adaptively generates pseudo-random sequence frame by frame according to the macroblock types,uses the pseudo-random sequence to randomly permute the coded block pattern (CBP) and the residual data in the coding information of a macroblock between macroblocks,changes the intra prediction modes of I macroblocks,and flips the signs of motion vector differences of P macroblocks and B macroblocks.Experimental results show that the proposed method can preserve format compatibility with H.264/AVC coding standard,and has characteristics of large encryption space,good key sensitivity,and small video bitrate variation.Compared with the existing encryption schemes,the proposed method performs better in terms of visual security and resistance to state of the art of sketch attack.

A linear low density polyethylene (LLDPE) light conversion film containing different concentrations of the light conversion agent [Eu(hfa)3(TPPO)2] was prepared, and its performance was evaluated. The scanning electron microscopy (SEM) results show that the surface of the polyethylene film containing [Eu(hfa)3(TPPO)2] is smooth, with no particle aggregation. The fluorescence spectra show that the light conversion film is excited in the ultraviolet region (200~345 nm) and exhibits strong emission in the red region (600~700 nm), matching the absorption range of chlorophyll. The result suggests that the light conversion film can absorb harmful ultraviolet light from sunlight for plant growth and convert it into the red light needed for plant growth, effectively achieving light quality regulation. The light conversion film containing 1.0% [Eu(hfa)3(TPPO)2] demonstrates the highest fluorescence quantum yield (66.38%). Under the natural light, the photosynthetic photon flux density (PPFD) transmitted through the light conversion film increases in the red region, indicating excellent light conversion performance. Ultraviolet-visible transmission spectra reveals a slight decrease in transparency compared to pure LLDPE film, indicating good light transmittance of the light conversion film. [ABSTRACT FROM AUTHOR]

【Abstract】 Objective: Total hip arthroplasty (THA) and hemiarthroplasty (HA) are effective methods currently used to treat femoral neck fracture in elderly patients, but the two options remain controversial in patients over 70 years old. The main purpose of our study was to determine whether THA or HA is a superior treatment of femoral fractures involving a displaced neck in patients who are over 70 years of age. Methods: A computer-based online search of Medline (1970-2011), PubMed (1977-2011), and the Cochrane Central Register of Controlled Trials (2002-2011) was conducted. Six relevant randomized controlled trials with a total of 739 patients were included for the final analysis. The analysis was performed with software RevMan 5.0. Results: We found that compared with THA, HA needed shorter average time and lost less blood. While over the long-term follow-up, THA patients exhibited significantly less pain and better function and were less likely to require a revision hip surgery. Postoperative infection was equally common among HA and THA patients. Conclusions: The significant differences in outcomes suggest that THA is a valuable treatment option for active elderly hip fracture individuals. However, patients who are older, impaired or institutionalized benefit from HA. Key words: Hip fractures; Arthroplasty, replacement, hip; Aged; Meta-analysis

Abstract: La, Nd, Sm, and Dy-doped Sr2Bi4Ti5O18 (SBTi) ceramic samples have been prepared by the solid-state reaction method. The X-ray diffraction reveals that all of the ceramic samples are single phase compounds. Their remnant polarization (2P r) increases at first, and then decreases with the increase of doping content. When doping content is 0.01, Sm and Dy-doped SBTi samples exhibit the maximum 2P r of 18.2 and 20.1μC/cm2, respectively. While La and Nd-doped SBTi samples display the maximum 2P r value of 18.4 and 19.1μC/cm2 with doping content of 0.05 and 0.10, respectively. The ferroelectric properties of Sr2Bi4− xLnx Ti5O18 are found to be dominated by the competition of the decrease of oxygen vacancy concentration and the relief of structural distortion. [Copyright &y& Elsevier]

Abstract: Vanadium incorporation in SrBi4Ti4O15 results in an improvement of electric properties. Raman scattering reveals that V-addition brings about the local disorders of structure, charge, and internal stress. The chemical valence of Bi and Ti does not increase after V-doping. The electric property improvement is originated from the restraint of oxygen vacancies, mobility weakening of the defects, and the vacancies produced at A-site. [Copyright &y& Elsevier]

Abstract: The ferroelectric ceramics of Bi4Ti3O12, SrBi4Ti4O15, and lanthanum-doped Bi4Ti3O12–SrBi4Ti4O15 were synthesized, and their Raman spectra were investigated. La-doping resulted in the enlargement of remnant polarization of Bi4Ti3O12–SrBi4Ti4O15. The structure of the Bi2O2 layers and TiO6 octahedra of the intergrowth was found to be different from those of Bi4Ti3O12 and SrBi4Ti4O15. La3+ ions exhibit pronounced selectivity for the occupation of A site as La content is lower than 0.50, and tend to be incorporated into Bi2O2 layers when the La content is higher than 0.50. Lanthanum substitution brings about the structural phase transition in Bi4Ti3O12–SrBi4Ti4O15. The variation of ferroelectric property may be attributed to combined contribution from the decreasing of the oxygen vacancies, the relaxation of the lattice distortion, the destroying of the insulation and the space charge compensation effects of the Bi2O2 slabs. [Copyright &y& Elsevier]