[en] Highlights: • A hydrothermal route to m-LaVO₄/BiOBr composite photocatalysts was proposed. • Products exhibit excellent photocatalytic activity under visible light. • Enhanced photocatalytic activity can be ascribed to forming p-n heterojunction. - Abstract: Visible-light driven m-LaVO₄/BiOBr composite photocatalysts were synthesized by a two-step hydrothermal process, and were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), photoluminescence spectroscopy (PL), and UV–vis diffuse reflectance spectroscopy, respectively. The results showed that 1.0 wt% LaVO₄/BiOBr sample exhibits the highest photodegradation rate of RhB under visible-light irradiation, within 60 mins, it achieved 83.37%. The enhanced photocatalytic performance can be ascribed to the formation of p-n heterojunction structure and the inhibition of m-LaVO₄ to 2D growth of BiOBr to a certain extent.

[en] Carbon nanotubes (CNTs) with 3 dimensional net-like structure were perfectly grown on C fiber at ambient temperature and pressure using a modified electrochemical process, and their composition and morphology were characterized by Raman spectroscopy, Energy dispersive spectroscopy (EDS), High resolution transmission electron microscopy (HRTEM), and Scanning electron microscopy (SEM), respectively. This paper also reported the influence of applied voltage and reaction time on the formation and growth of CNTs, and proposed a possible growth mechanism. - Highlights: • CNTs with 3D net-like structure were grown on C fiber by an “electrochemical” route. • The formation and growth of CNTs relied on applied voltage and reaction time. • A possible growth mechanism was proposed.

[en] Objective: To analyze the clinical value of combined CT pulmonary angiography (CTPA) and D-dimer in detecting pulmonary embolism patients with acute chest pain. Methods: There were 155 patients (83 males and 72 females, age from 13-84 years, mean age of 55 ± 16 years) with chest pain who underwent CTPA during Jan. 1st, 2015 to June 30, 2017 in our Department of Emergency were retrospectively studied. The presence and incidence of pulmonary embolism, clinically implicated concurrent lesions in patients without pulmonary embolism, and D-dimer value were recorded and analysed. Incidences of pulmonary embolism in positive and negative D-dimer groups were compared with Fisher's exact test. D-dimer values between pulmonary embolism patients and non-pulmonary embolism patients in abnormal D-dimer patients were compared with independent sample t test. With CTPA findings as reference standard, the diagnostic performance of D-dimer was calculated for diagnosing pulmonary embolism. Results: Of 155 patients, 50 patients were diagnosed as having pulmonary embolism (32.3%), while 105 patients (67.7%) had no pulmonary embolism. There were 152 patients had D-dimer measurement. With 0.5 mg/dL as cut-off value, 128 patients had elevated D-dimer and 24 patients had normal D-dimer value. No pulmonary embolism was detected in CTPA in all 24 patients with normal D-dimer value (0/24), while 50 patients with pulmonary embolism (50/128, 39.1%) and 78 patients without pulmonary embolism in CTPA had elevated D-dimer value. Statistical difference was found between the incidences of pulmonary embolism in the positive and negative D-dimer groups (Fisher's exact test, P < 0.001). In abnormal D-dimer group, 50 patients had pulmonary embolism in CTPA while 78 patients had no pulmonary embolism in CTPA, no significant difference was found for their mean D-dimer values (6.11 ± 5.59 mg/dL vs 5.26 ± 6.67 mg/dL; t = 0.741, P = 0.460). With CTPA findings as reference standard, the sensitivity, specificity, negative predictive value, and positive predictive value of D-dimer for diagnosing pulmonary embolism were 100%, 23.5%, 39.1%, and 100%, respectively. Conclusions: Combining the D-dimer measurements can improve the positive findings of pulmonary embolism in CTPA. (authors)

[en] Coal-bed methane(CBM)was a natural gas occurring in underground coal seams, which was mainly composed of methane. In order to study the effect of ignition energy and pressure on the explosion limit of CBM, a special environment 20L explosion characteristic test system was used. The explosion limit of methane under different ignition energy(10∼400J)and pressure (0.1∼1.2MPa)was studied experimentally. The results show that with the increase of ignition energy and initial pressure, the upper limit of methane explosion was obviously increased, the lower limit of explosion was decreasing, and the range of explosion limit was enlarged. Compared with the lower limit of methane explosion, the effect of ignition energy and initial pressure on the upper limit of methane explosion was more obvious. The coupling effect of ignition energy and initial pressure on the explosion limit of methane was greater than that of a single factor, and the effect of ignition energy and initial pressure on the explosion limit was more significant than that of a single factor. (paper)

[en] Bismuth molybdate (Bi_3.64Mo_0.36O_6.55) powders as a novel photocatalyst was prepared using Bi(NO₃)₃.5H₂O and Na₂MoO₄.2H₂O as raw materials by a simple low temperature molten salt method at 160 ^oC for 2 h. The as-prepared samples were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-visible (UV-vis) absorption spectra. The photocatalytic activity of Bi_3.64Mo_0.36O_6.55(BMO) nanocrystals was evaluated using the photocatalytic oxidation of rhodamine B (RhB) at room temperature under ultraviolet irradiation. The factors affecting the photocatalytic activity, such as photocatalysts concentration, RhB concentration and compressed air as the assisted oxidant species additives, had been studied.

[en] The flake-like nanoscale γ-bismuth molybdate (Bi₂MoO₆) powders as a novel photocatalyst was prepared using Bi(NO₃)₃.5H₂O and Na₂MoO₄.2H₂O as raw materials by a simple low-temperature molten salt method at 350 deg. C for 1, 4 and 8 h, respectively. The as-prepared samples were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis absorption spectra (UV-vis). The photocatalytic activity of Bi₂MoO₆ crystals was evaluated using the photocatalytic oxidation of rhodamine B (RhB) at room temperature under ultraviolet irradiation. It was found that the band gap adsorption edge of Bi₂MoO₆ is estimated to be 477 nm corresponding to the band gap energy to be 2.60 eV. In addition, the Bi₂MoO₆ powders exhibit good photocatalytic properties to photodegrade RhB at room temperature. Finally, the mechanism of photocatalytic property of Bi₂MoO₆ had been also discussed

[en] Nanocrystalline SrNb₂O₆ powders were successfully prepared by a simple electrochemical method for the first time, and the influences of electrolytic solution ingredients, electrolyte concentration, and applied electric current intensity on electrochemical process and products were systemically studied. It was found that the formation of strontium niobates strongly relied on the basic or acidic condition of electrolytic solution. When Sr(OH)₂.8H₂O or mixed Sr(OH)₂.8H₂O with SrCl₂.6H₂O was used as electrolyte, Sr₅Nb₄O₁₅ and SrNb₂O₆ phases could simultaneously form, and the relative ratio of Sr₅Nb₄O₁₅ phase to SrNb₂O₆ declined with the increase of SrCl₂.6H₂O content in electrolytic solution. The higher the basicity of electrolytic solution, the more favored the crystallization and development of Sr₅Nb₄O₁₅ phase. Only monoclinic phase SrNb₂O₆ was obtained in neutral SrCl₂.6H₂O solution or acidic solution of SrCl₂.6H₂O with adding hydrochloric acid solution, and a lower concentration of SrCl₂.6H₂O (≤0.50 M) was beneficial to the formation of SrNb₂O₆ phase and stable anodic sparks could be observed. Moreover, the crystallization and development of the nanocrystalline SrNb₂O₆ powders seem to be not sensitive to the applied electric current intensity, their similar particle size and morphology ultimately result in the resemblance in UV-vis absorption and photodegradation. They show a slight red shift of light absorption onset and better photocatalytic performance compared with that prepared by the solid-state reaction.

[en] A good quality of ZnO coating was successfully fabricated on carbon fiber at ambient temperature and pressure by a modified electrochemical method (“electrochemical” growth), where a carbon fiber was used as both a heating source and substrate, and ethanol solution of zinc acetate dihydrate as an electrolyte. The composition, microstructure and morphology, and photoluminescence property of the as-synthesized ZnO coating were characterized by XRD, Raman spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, and photoluminescence spectra technologies, respectively. A possible formation mechanism was initially proposed even though more detailed study will be needed. A variety of ZnO coatings with different morphologies can be easily prepared within several tens seconds through this approach, e.g. homogeneous and dense particle shape, mesoporous structure, and Y-shape split ribbon. Our results show that the “electrochemical” growth processes obvious advantages, and it can be expected to extend to the fabrication of other oxide coatings. - Highlights: • ZnO coating was fabricated on carbon fiber by an “electrochemical” growth. • The process proceeded at ambient temperature and pressure within several tens sec. • The particle morphology in ZnO coatings depended on processing parameters.

[en] Nanosized W-doped TiO₂ photocatalysts were synthesized by a simple hydrothermal method, and characterized by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface area analyzer. The photocatalytic activity of undoped TiO₂ and W-doped TiO₂ photocatalysts was evaluated by the photocatalytic oxidation degradation of methyl orange in aqueous solution. The results show that the photocatalytic activity of the W-doped TiO₂ photocatalyst is much higher than that of undoped TiO₂, and the optimum percentage of W doped is 2.0 mol%. The enhanced photocatalytic activity of the doped photocatalyst may be attributed to the increase in the charge separation efficiency and the presence of surface acidity

[en] CoWO₄ nano-particles were successfully synthesized at a low temperature of 270 deg. C by a molten salt method, and effects of such processing parameters as holding time and salt quantity on the crystallization and development of CoWO₄ crystallites were initially studied. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescent spectra techniques (PL), respectively. Experimental results showed that the well-crystallized CoWO₄ nano-particles with ca. 45 nm in diameter could be obtained at 270 deg. C for a holding time of 8 h with 6:1 mass ratio of the salt to CoWO₄ precursor, and XRD analysis evidenced that the as-prepared sample was a pure monoclinic phase of CoWO₄ with wolframite structure. Their PL spectra revealed that the CoWO₄ nano-particles displayed a very strong PL peak at 453 nm with the excitation wavelength of 230 nm, and PL properties of CoWO₄ crystallites relied on their crystalline state, especially on their particle size.