Search

Owing to the presence of Mn-Br bonds, the conduction band electrons of BiOBr are directed towards MnCo 2 O 4 , where they recombine with valence band holes, thereby preserving the robust redox activity of the photogenerated carriers and activating peroxymonosulfate in synergy with Mn and Co. [Display omitted] • Synthesis of smartly-designed BiOBr/MnCo 2 O 4 photocatalysts with abundant interface Mn-Br bonds. • Mn-Br bonds as electron transport bridge facilitate charge-flow steering. • The exposure of the {1 1 0} facets exhibited more Mn atom-anchored sites for easy anchoring of BiOBr. • The prepared BM-25 catalyst had a marigold-like morphology with good adsorption properties. • The constructed BM-25 exhibited brilliant photocatalytic activity. Precise charge transfer modification and efficient activation of peroxymonosulfate are effective methods for increasing photocatalytic efficiency. Here, BiOBr/MnCo 2 O 4 photocatalysts with abundant Mn-Br bonds were generated by immobilizing the exposed {1 1 0} facets of BiOBr in the marigold-like MnCo 2 O 4. The prepared BiOBr/MnCo 2 O 4 retained the marigold-like morphology of MnCo 2 O 4 while exhibiting good adsorption properties and interface contact effects. More importantly, the interfacial Mn-Br bond between MnCo 2 O 4 and BiOBr functioned as charge transport bridges, allowing for a directional transfer channel and lowering the potential energy barrier for interfacial charge transfer. In addition, the exposure of the {1 1 0} facets exhibited more Mn atom-anchored sites for easy anchoring of BiOBr, significantly solving the stability problem of the bismuth material. Compared to MnCo 2 O 4 + BiOBr, which did not form Mn-Br bonds, the MnCo 2 O 4 /BiOBr heterojunction had more efficient photocatalytic activity (1.3 times) and stability. This suggested that using electronic bridges for directional charge transfer was an efficient way to improve photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] Mercury pollution is a significant threat to the environment and health worldwide. Therefore, effective and low-cost absorbents that are easily scalable are needed for real-world applications. Enlarging the surface area of the materials and doping with heteroatoms are two of the most common strategies to cope with this problem. Sulfur-doped activated carbon synthesized from the carbonization of inverse vulcanized thiopolymers makes it possible to combine both large specific surface area and doping of heteroatoms, resulting in outperformance in mercury uptake against commercial activated carbons. Convenient recovery of mercury absorbents after treatment should be beneficial in mercury collecting and recycling. Therefore, magnetic sulfur-doped carbons (MSCs) were prepared by functionalizing sulfur doped carbons through chemical precipitation with magnetic iron oxides. Besides the characterisations of materials, mercury uptake experiments, such as stactic test, capacity test, impact of solution pH, and mixed ions interferences were performed. These MSCs exhibit high specific surface area (1,329 m2/g), high sulfur content (up to 14.8 wt%), porous structure, low cost, and are convenient for retrieval. MSCs are demonstrated high uptake capacity (187 mg g-1) and efficiency in mercury solution and multifunctional absorption in mixed ions solution, showing their potential to be applied in water purification and environmental remediation. [ABSTRACT FROM AUTHOR]

• The solubility of 4GABCL was determined for the first time. • The determination coefficients of mathematical model fitting are all greater than 0.999, which proves that the fitting effect is good. • The thermodynamic properties of mixing and dissolution were calculated using Wilson model and solubility data. The solubility of 4-guanidinobenzoic acid hydrochloride (4-GABCL) in pure solvents (H 2 O, methanol, ethanol, n-propanol, isopropanol, 1-butanol, and 1-pentanol) and two binary solvents (H 2 O + ethanol/isopropanol) were determined by the dynamic saturation method in the temperature range of 294.55 K–333.65 K under atmospheric pressure. From the measurement results, it could be observed that the solubility of 4-GABCL in both pure and binary solvents all increased with increasing temperature. The solubility order of 4-GABCL in pure solvents was ranked as follows: methanol > H 2 O > n-propanol > ethanol > n-butanol > isopropanol > n-pentanol. The solubility of 4-GABCL in binary solvents tended to increase and then decrease with increasing molar fractions of ethanol and isopropanol, and the solubility of the solute in the binary solvents was greater than that of each in the monosolvents. In addition, Ideal model, Apelblat model, λh model, Wilson model, and NRTL model had been used to correlate the solubility of 4-GABCL in pure and binary solvents. Correlated effects show that the Wilson model gives the best correlation. The influence of solvents on the solubility of 4-GABCL was further studied by KAT-LSER model. The results showed that the solubility was mainly affected by the polarizability and the self-viscosity of the solvent.The mixing and dissolution thermodynamic properties of 4-GABCL in all experimental solvents had been calculated and analyzed by using the Wilson equation and solvent data. It was determined that the mixing and dissolution of 4-GABCL were spontaneous, endothermic and entropy-driven in the study systems. Besides, the solubility order of the pure solvent is consistent with the dissolution entropy at a temperature of 318.15 k. [ABSTRACT FROM AUTHOR]

Hafnium carbide (HfC) whiskers were successfully synthesized by combining hydrothermal and carbothermal reduction. The precursor of HfC whiskers was prepared by the hydrothermal method, subsequently pyrolyzed, and reduced to HfC whiskers at 1500–1700 °C. The synthesis parameters of HfC whiskers at various temperatures, C/Hf molar ratios, and NaF concentrations were investigated in detail. The whiskers with diameters of 1–3 μm and lengths of 50–90 μm were prepared by pyrolyzing the precursors with a C/Hf molar ratio of 6 at 1700 °C. The experimental results and thermodynamic analysis demonstrated that the growth of HfC whiskers was governed by the vapor-liquid-solid (VLS) mechanism. Furthermore, the prepared HfC whiskers were added to the ZrB 2 -HfO 2 coatings on the surface of tungsten-rhenium substrates in different ratios to toughen the coatings. The thermal shock test results indicated that the coatings toughened with HfC whiskers had better thermal shock resistance. In particular, the maximum number of thermal shock cycles that 6%HfC W -ZH could withstand was five times higher than that of W–Re alloy and about one time higher than that of ZH coatings without HfC whiskers. The thermal shock resistance of the ZrB 2 -HfO 2 coatings was significantly improved by adding HfC whiskers. Here, the HfC whiskers with diameters of 1–3 μm and lengths of 50–90 μm were effectively synthesized by hydrothermal and carbothermal reduction methods. The growth mechanism of HfC whiskers can be explained by the vapor-liquid-solid (VLS) mechanism. Furthermore, the prepared HfC whiskers were added to the ZrB 2 -HfO 2 coatings on the surface of tungsten-rhenium substrates in different ratios to toughen the coatings. The W-26Re substrate could be effectively protected by the 6%HfC W -ZH coating, which could withstand the most thermal shock cycles (474).(a) Hydrothermal synthesis of HfC whiskers. (b) Toughening effect on ZrB2-HfO2 coatings by adding HfC whiskers. [Display omitted] • Hafnium carbide (HfC) whiskers were successfully synthesized by combining hydrothermal and carbothermal reduction. • The synthesis parameters and growth mechanism of HfC whiskers were investigated. • The thermal shock resistance of the ZrB 2 -HfO 2 coatings was significantly improved by adding slef-prepared HfC whiskers. [ABSTRACT FROM AUTHOR]

To understand the environmental friendliness and high efficiency of organic materials during remediating soil polluted by heavy metals by assessing the feedback of soil ecosystems after organic materials were put into polluted soil. Incubation research was undertaken to examine the impact of amendments ranging from 0.1% to 3.0% (w/w), including single cow bone meal (BM), single oyster shell meal (OS), and a composite of 50% BM mixed with 50% OS (BO) on soil biochemical properties. The findings revealed that the implementation of BM and OS increased soil pH, the content of certain nutrients, and the activities of catalase (S-CAT), and urease (S-UE) while decreasing the availability of Cd, Pb, Cu, and Zn. Overall, the immobilization effect on Cd and Zn after a 108-day incubation was ranked as follows: BM group > OS group ≥ BO group, and the order of the immobilization effect of Pb and Cu was OS group > BO group > BM group. In addition, the dominant bacterial community flora shifted toward alleviating the re-dissolution of metal ions from the soil and promoting nutrient recycling in soil within 108 days of cultivation. RNA analyses showed that the strongest determinants for microbial communities between BM application and OS application at the genus level were soil pH, CEC, and heavy metal (Cd, Pb). These results increase our understanding of the leaching performance of Cd, Pb, Cu and Zn and the evolution trend of microorganisms when organic amendments remediate heavy metal contaminated soil. [Display omitted] • The mobilization of Cd, Pb, Cu, and Zn in soil is reduced by BM and OS. • The activity of CAT and UA in soil will increase with the addition of BM and OS. • Soil microorganisms evolve in a direction that reduces re-dissolution of metal ions. • CEC, Cd and Pb were determinants of soil microbial community in addition to pH. [ABSTRACT FROM AUTHOR]

In the race of arms between attackers, trying to build more and more realistic face replay attacks, and defenders, deploying spoof detection modules with ever-increasing capabilities, CNN-based methods have shown outstanding detection performance thus raising the bar for the construction of realistic replay attacks against face-based authentication systems. Rather than trying to rebroadcast even more realistic faces, we show that attackers can successfully fool a face authentication system equipped with a deep learning spoof detection module, by exploiting the vulnerabilities of CNNs to adversarial perturbations. We first show that mounting such an attack is not a trivial task due to the unique features of spoofing detection modules. Then, we propose a method to craft adversarial images that can be successfully exploited to build an effective replay attack. Experiments conducted on the REPLAY-MOBILE database demonstrate that our attacked images achieve good performance against a face recognition system equipped with CNN-based anti-spoofing, in that they are able to pass the face detection, spoof detection and face recognition modules of the authentication chain. • Unique features of CNN-based spoofing detection impedes adversarial examples. • Adversarial attacks must act in a pre-emptive way in physical domain. • Our attack can pass face detection, spoof detection, face recognition simultaneously. [ABSTRACT FROM AUTHOR]

• The solubility of Sulfaguanidine(SG) was investigated in pure and binary solvents. • The solubility data of SG was well correlated by six different models. • The solventisation effect was analysed using the KAT-LSER model. • The intermolecular forces of SG were explored using Hirshfeld surface analysis and a two-dimensional fingerprint was plotted. • Thermodynamic properties of SG were studied and discussed in dissolution process. The solubility of sulfaguanidine(SG) in water, methanol, ethanol, n-propanol, isopropanol, n-butanol and binary solvent systems (water + methanol/n-propanol) was determined by the synthetic method at local pressure values in the temperature range of 288.15 K to 343.15 K. The experimental data were compiled and plotted, and it can be seen that the solubility of SG in the six pure solvents and two binary solvent systems in the selected temperature range increased monotonically with increasing temperature. The solubility of SG in pure solvents was in the order of methanol > ethanol > n-propanol ≈ isopropanol > n-butanol > water. The solubility of SG in the mixture of water + methanol increased with the composition of the benign solvent, while the solubility in the mixture of n-propanol + water increased first and then decreased with the increase of the benign solvent. In addition, the Van't Hoff model, Apelblat model, λh model and Wilson model were cited to correlate the solubility data of SG in pure and binary solvents, and additionally the binary models Apelblat-Jouyban-Acre (A-JA) model and Van't Hoff-Jouyban-Acre model were used to fit the solubility of SG in two binary solvents. The RAD and RMSD values show that the chosen models both show good correlation. The solvent effect was analyzed using the KAT-LSER model and the solubility of SG in the solvents used was mainly influenced by non-polarity and viscosity. After that, the inter-molecular forces of SG were explored using Hirshfeld surface analysis and a two-dimensional fingerprint was plotted. Finally, the thermodynamic properties of SG in all solvent systems, including Gibbs free energy, entropy and enthalpy, were calculated using Van't Hoff equation and the experimentally measured solubility data. [ABSTRACT FROM AUTHOR]

A SiO 2 based polymeric composite coating is developed via a facile strategy to get fire resistance for wooden materials. The composite coatings exhibit strong interfacial adhesion to versatile flammable substrates. The coating-treated wood features well flame resistance, a high LOI of 48.0%, a desired V-0 rating during vertical burning, low heat release rate and long ignition time. [Display omitted] Fire resistant coatings have been proven as an efficient way to improve fire safety in three aspects: reducing the Heat Release Rate (HRR), delaying the ignition time and preventing heat transfer. Herein, a SiO 2 based polymeric composite coating with a lower thermal conductivity and brilliant fire resistance was developed. Isocyanate and sodium silicate could form the final Si-O-Si network structure by polymerization. Compared to the wood without coating, the coated wood shows a significantly increase in limit oxygen index (LOI), has reached 48.0 vol% in the test. As for the cone calorimetry test, coated wood shows a 55.3% decrease in the first peak Heat Release Rate (pHRR) and the Total Heat Release (THR) obtains fire-resistant standard. After exposed to butane flame for 30 mins, the coated wood could still maintain its structural integrity with only 180℃ on the non-exposed side. The commercial standard test of the coating was also investigated. To better understand what role does the polyurea play in the system, a theoretical calculation was done during the research to discuss the interaction between the silica and polyurea. As a fast brush-formed coating, it exhibits a great potential in the field of fire-resistant materials, and may broaden the application prospects of wood. [ABSTRACT FROM AUTHOR]

Background and aims Consecutive climatic extremes have more intense impacts on natural ecosystems and human activities than occasional events. There were many studies about the frequency or intensity of extreme weather events, but few focused on the consecutiveness or continuousness of climatic extremes. We analyzed the temporal and spatial distributions and tendencies in the consecutive temperature and precipitation extremes in China during 1961–2015. Methods Daily temperature and precipitation data at 1867 meteorological stations over China was used and four consecutive indices of climate extremes, i.e. cold spell duration indicator (CSDI), warm spell duration indicator (WSDI), consecutive dry days (CDD) and consecutive wet days (CWD), were calculated by RClimDex 1.0. Linear trends in the time series of consecutive days of temperature and precipitation extremes were examined and their statistical significance was evaluated using Mann–Kendall test. Results and discussion There were obvious differences in the spatial distributions of consecutive days of climate extremes in China. During 1961–2015, CSDI and CWD decreased significantly at rates of 0.9 and 0.1 days per decade respectively, while WSDI increased significantly at rate of 0.8 days per decade in China. Spatially, CSDI decreased at rates of 0–3.0 days per decade in almost all parts of China, and WSDI increased at rates of 0–2.0 days per decade in most parts of China. The spatial trends of CDD and CWD were significant only in several regions of China. CSDI and WSDI had higher percent changes than those of CDD and CWD. Changes in the CSDI and WSDI were associated with large-scale oceanic and atmospheric circulation oscillations, such as Atlantic Multidecadal Oscillation (AMO), El Niño/Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). With global warming, there will be fewer cold extremes, more frequent hot extremes and precipitation extremes. Conclusions Given the increases in the frequency and intensity of some consecutive climatic extremes and an increasing physical exposure and socio-economic vulnerability to such extremes in China, more strategies and capacities of mitigation and adaptation to consecutive climatic extremes are essential for the local government and climate-sensitive sectors. [ABSTRACT FROM AUTHOR]

Ion sieving is essential for biological systems and membrane-based applications. At present, metal-organic framework (MOF) membranes are of great interest for use in ion separation, but it remains a great challenge to design high quality MOF membranes with a simple preparation process and desirable ion selectivity. Herein we fabricate a MOF composite membrane, containing highly penetrated ZIF-8 channels. The ZIF-8 channels are the dominant pathways for ion transport and display a good Li+/Mg2+ sieving performance (Li+/Mg2+ ​= ​6.1). The simulation reveals that the Li+/Mg2+ selectivity is associated with the significant disparity of transport energy barrier between them, which is caused by the different extent of ion dehydration in angstrom-scale ZIF-8 channels. This work provides an effective strategy to develop ionic sieving membranes based on penetrating MOF channels for lithium extraction. A novel composite membrane with penetrating ZIF-8 channels was constructed for efficient Li+/Mg2+ sieving, which was based on the steric effect. [Display omitted] • A novel composite membrane with penetrating ZIF-8 channels was fabricated by vacuum filtration and casting. • The MOFs composite membrane exhibits efficient Li+/Mg2+ sieving, which was mainly based on the ion dehydration effect. • Ion will undergo a continuous "dehydration-rehydration" cycle when it transports through the MOF channel. [ABSTRACT FROM AUTHOR]