[en] With the adoption and diffusion of data sharing paradigm in cloud storage, there have been increasing demands and concerns for shared data security. Ciphertext Policy Attribute-Based Encryption (CP-ABE) is becoming a promising cryptographic solution to the security problem of shared data in cloud storage. However due to key escrow, backward security and inefficiency problems, existing CP-ABE schemes cannot be directly applied to cloud storage system. In this paper, an effective and secure access control scheme for shared data is proposed to solve those problems. The proposed scheme refines the security of existing CP-ABE based schemes. Specifically, key escrow and conclusion problem are addressed by dividing key generation center into several distributed semi-trusted parts. Moreover, secrecy revocation algorithm is proposed to address not only back secrecy but efficient problem in existing CP-ABE based scheme. Furthermore, security and performance analyses indicate that the proposed scheme is both secure and efficient for cloud storage.

[en] Highlights: • Three-dimensionally ordered macroporous (3DOM) MnCeTi catalysts synthesized. • The 3DOM catalysts have high surface area to expose more active sites. • The addition of Ti promoted the N₂ selectivity. • The MnCeTi catalysts showed remarkable H₂O tolerance. • In situ DRIFT analysis confirmed the SCR reaction followed the L-H mechanism. A series of 3DOM-Mn_xCe_yTi_z catalysts with three-dimensionally ordered macroporous (3DOM) structure were synthesized by a soft template method. The high SCR activity of the 3DOM-Mn₃Ce₁ catalyst at low temperature was owing to the excellent redox ability and rich Lewis and Brønsted acid sites of the catalysts, which were beneficial to improve the catalytic activity. However, the strong oxidizability of MnO_x resulted in the nonselective oxidation of NH₃ and generation of N₂O, decreasing the N₂ selectivity. After addition of Ti, the redox capacity of the 3DOM-Mn₃Ce₁Ti₁ catalyst decreased, and the NH₃ were strongly adsorbed on the acid sites, which enhanced the N₂ selectivity with a broadened temperature window of 240–440 °C and a high GHSV of 120000 h⁻¹. Furthermore, both the 3DOM-Mn₃Ce₁ and 3DOM-Mn₃Ce₁Ti₁ catalysts showed remarkable tolerance of H₂O. Finally, through in situ DRIFT analysis, the Langmuir-Hinshelwood (L-H) mechanism was confirmed as the dominant reaction pathway over the 3DOM-Mn₃Ce₁Ti₁ catalyst.

[en] A pure material proportion estimation method based on a spectral database is proposed. The method transforms the non-negative and linear constraints into a pure material proportional cost function minimization problem with a linear mixed model. The Newton algorithm is used to optimize the cost function, and the optimized extreme value is the optimal estimate of the proportion of pure material. Spectral simulation experiments are carried out for space target materials using the US Geological Survey database, and the experimental results show that the method proposed in this paper can help to estimate the proportion of pure substances in such targets quickly and accurately, especially when the number of mixed pure materials is large. Compared with some existing common algorithms, the proposed method is robust and can estimate the proportion of pure material in a space target when the signal-tonoise ratio is less than 40 dB. The accuracy of the method is 30% higher than that of the existing method.

[en] This paper proposes a multi-stage magnetic valve controllable reactor based on the traditional magnetic valve controllable reactor (MCR). According to the structural characteristics of multi-stage magnetic valve, the mathematical model of harmonic characteristics of multi-stage MCR device is established, and the cross-section parameters of each magnetic valve are optimized by immune algorithm. The results show that after the number of magnetic valve stages exceeds 3, the optimization of total harmonics is reduced, and both are lower than the national common harmonic standard. Finally, the established mathematical model is verified by simulation. The results show that the three-stage and above magnetic valve structure can control the harmonic current under the national standard. The four-stage MCR can suppress the harmonics well and improve the power quality input to the distribution network. (paper)

[en] Highlights: • The BiOI/Zn₂SnO₄ photocatalysts were prepared by a mild wet chemical method. • The ZB-1/2 (Zn to Bi molar ratio = 1/2) exhibits the best photocatalytic activity. • The enhanced performance results from high separation of photogenerated carriers. - Abstract: New BiOI/Zn₂SnO₄ p–n heterojunction photocatalysts were prepared by anchoring n-type Zn₂SnO₄ nanoparticles on p-type BiOI plates. The physicochemical characteristics of the catalysts were studied by X-ray powder diffraction pattern (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Ultraviolet visible (UV–vis) diffuse reflectance spectroscopy (DRS), nitrogen adsorption–desorption, and photoelectrochemistry measurement. The as-prepared catalysts exhibited excellent photocatalytic activity for the decomposition of methyl orange (MO) under visible light irradiation. The enhanced photocatalytic performance of BiOI/Zn₂SnO₄ was not only attributed to the matched band potentials but also the interconnected heterojunction of BiOI and Zn₂SnO₄ nanoparticles

[en] Soil contamination with heavy metals is a worldwide problem especially in China. The interrelation of soil bacterial community structure, antibiotic resistance genes, and heavy metal contamination in soil is still unclear. Here, seven agricultural areas (G1–G7) with heavy metal contamination were sampled with different distances (741 to 2556 m) to the factory. Denaturing gradient gel electrophoresis (DGGE) and Shannon index were used to analyze bacterial community diversity. Real-time fluorescence quantitative PCR was used to detect the relative abundance of ARGs sul1, sul2, tetA, tetM, tetW, one mobile genetic elements (MGE) inti1. Results showed that all samples were polluted by Cadmium (Cd), and some of them were polluted by lead (Pb), mercury (Hg), arsenic (As), copper (Cu), and zinc (Zn). DGGE showed that the most abundant bacterial species were found in G7 with the lightest heavy metal contamination. The results of the principal component analysis and clustering analysis both showed that G7 could not be classified with other samples. The relative abundance of sul1 was correlated with Cu, Zn concentration. Gene sul2 are positively related with total phosphorus, and tetM was associated with organic matter. Total gene abundances and relative abundance of inti1 both correlated with organic matter. Redundancy analysis showed that Zn and sul2 were significantly related with bacterial community structure. Together, our results indicate a complex linkage between soil heavy metal concentration, bacterial community composition, and some global disseminated ARG abundance.

[en] Highlights: • A modified PAS was used to simultaneously collect gaseous SVOCs and particles. • PCB 11 was identified and quantified in indoor environments for the first time. • PCBs and pesticides were from indoor while PAHs were influenced by outdoor sources. • Indoor pesticide levels in Australia were among the highest in the world. • The highest EDI value was estimated for permethrin, mostly via exposure to dust. -- Abstract: Paired indoor air and floor dust samples were collected from residential houses and offices (n = 28) in two Australian cities in 2015. For the air samples, a modified passive air sampler (PAS) was used to collect semi-volatile organic compounds (SVOCs) in gaseous phase and airborne particles simultaneously. Sampling rates (R) of the PAS for gaseous SVOCs ranged from 0.69 to 3.4 m³ sampler⁻¹ day⁻¹. Out of the 33 analytes, 22, 14 and 17 compounds were detected (above the method detection limit) in over 50% of air, airborne particles and floor dust samples respectively. The highest median level in air, airborne particles and floor dust was observed for phenanthrene (2.0 ng m⁻³), permethrin (8800 ng g⁻¹) and permethrin (5100 ng g⁻¹) respectively. Among polychlorinated biphenyl (PCB) congeners, with few exceptions, the largest contribution was from 3,3′-dichlorobiphenyl (PCB11) for both indoor air and floor dust samples. In these houses and offices, the indoor level of polycyclic aromatic hydrocarbons (PAHs) was mainly influenced by ambient (outdoor) air. Primary sources of PCBs were from within indoor environments and generally older houses have higher concentrations in air. Among pesticides, hexachlorobenzene in indoor environments appeared to be due to transfer from outdoor sources whereas chlordanes and pyrethroids were associated with past and current household application respectively. Compared to data from other countries/regions, concentrations of chlordanes, chlorpyrifos and pyrethroids in indoor air and dust samples from Australia were among the highest whereas PCB and PAH levels were among the lowest. The sum of estimated daily intakes (EDIs) via inhalation and dust contact and ingestion were calculated. The highest median value of EDI was observed for permethrin at 2.8 (for adults) and 74 ng kg⁻¹ day⁻¹ (for toddlers), which are < 0.15% of the U.S. EPA reference dose.