[en] Uranium has been determined in seawater, biological samples and sediments using laser induced fluorescence spectrometry (LIFS). The biological samples and sediments are digested with a mixture of HNO_3, HClO_4 and HF. The conductivity of the seawater should be below 5.0 mS and the pH of the sample should be in the range 6.5-9.0. The volume of the reagent used to enhance the fluorescence intensity was 0.5 ml. Comparison with other methods was favorable, LIFS being rapid, simple and sensitive, and well suited to environmental monitoring. (author)

[en] The NO emission of pulverized coal during combustion in the O₂/N₂ atmosphere and O₂/CO₂ atmosphere was studied by using the sedimentation furnace test bed. The effects of CO₂ concentration, temperature and excess air concentration on the NO emission characteristics of single coal and mixed coal The results show that the NO content of the pulverized coal is lower than that of the O₂/N₂ combustion atmosphere, and the decrease of the NO content in the O₂/CO₂ atmosphere is about 30%∼35%. When the CO₂ concentration changes from 20% to 50% of the process, the amount of NO produced in the selected coal gradually decreased, the change range is not large; with the pulverized coal combustion temperature continues to rise, the selected coal in the two kinds of atmosphere combustion NO content increased And the NO emission concentration is more obvious in the O₂/N₂ atmosphere. When the temperature reaches 1200°C and 1500°C the slope of the NO emission curve can be found to vary greatly. With the increase of the excess air coefficient α Increase, in these two atmosphere NO production also showed a rising trend. (paper)

[en] By employing the infiltration growth (IG) technique, Mg-doped Nd–Ba–Cu–O (NdBCO) seed crystals were successfully prepared through 1 wt% MgO addition both to a Nd₄Ba₂Cu₂O₁₀ (Nd-422) precursor powder and to a liquid source with the composition Nd₂O₃:CuO:BaCuO₂ = 1:6:10. Differential thermal analysis (DTA) results showed that the decomposition temperature of the processed Mg-doped NdBCO crystals increased by about 20 °C compared with the general, Mg-free NdBCO seeds, thus they can be used as generic seed crystals to induce the growth of any RE–Ba–Cu–O (REBCO) single grain. This result is consistent with that observed in melt growth (MG) processed Mg-doped NdBCO crystals. Finally, highly c-axis oriented Gd–Ba–Cu–O (GdBCO) and Y–Ba–Cu–O (YBCO) large grains were successfully grown using the produced seed crystals. (paper)

[en] Highlights: • Implanted TiO_2 films with excellent antibacterial and photocatalytic ability was prepared. • Bactericidal effect of released Ag ions was confirmed using VC as radical scavenger. • Excitation of TiO_2 to visible region is attributed to subtitutional Ag. • Synergetic effect of Ag"3"+ and Ag"+ accounts for the enhanced ability of TiO_2. - Abstract: TiO_2 thin films were deposited by spin coating method. Silver ions were implanted into the films using a Metal Vapor Vacuum Arc implanter. The antibacterial ability of implanted films was tested using Escherichia coli removal under fluorescent irradiation and in the dark. The concentration of E. coli was evaluated by plating technique. The photocatalytic efficiency of the implanted films was studied by degradation of methyl orange under fluorescent illumination. The surface free energy of the implanted TiO_2 films was calculated by contact angle testing. Vitamin C was used as radical scavengers to explore the antibacterial mechanism of the films. The results supported the model that both generation of reactive oxygen species and release of silver ions played critical roles in the toxic effect of implanted films against E. coli. XPS experimental results demonstrated that a portion of the Ag(Ag"3"+) ions were doped into the crystalline lattice of TiO_2. As demonstrated by density functional theory calculations, the impurity energy level of subtitutional Ag was responsible for enhanced absorption of visible light. Ag ion-implanted TiO_2 films with excellent antibacterial efficiency against bacteria and decomposed ability against organic pollutants could be potent bactericidal surface in moist environment.

[en] Field emission characteristics of carbon nanotube arrays synthesized by thermal chemical vapor deposition on iron ion pre-bombarded silicon substrate are enhanced by titanium ion irradiation. A pronounced degradation of turn-on electric field of 0.305 V/μm and threshold field, of which the lowest value is only 1.054 V/μm, about 0.482 V/μm at the dose of 5 x 10¹⁶ ions/cm² is as an expression of this enhancement. Scanning electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Photoelectron spectrometer and transmission electron microscopy are measured for comparison before and after the Ti ion irradiation of the carbon nanotube arrays, and the results reveal that the formation of carbon nanorod/nanotube heterostructure during ion irradiation plays a dominative role in the promotion of the field emission properties. However, high-dose irradiating transaction on carbon nanotube arrays will exert repulsive effects on the field emission characteristics for the introduction of severe structural damage. Additionally, the longtime eminent stability behaviors under high applied fields have provided a possibility for the potential application of field emission flat panel display or electron emitters based on carbon nanotube arrays.

[en] We report here a systematic study of the field emission (FE) properties of highly ordered carbon nanotube (CNT) arrays at different temperatures. The FE characteristics of the CNT arrays are significantly improved with temperature increasing from 298 K to 473 K, as evidenced by the decreases of turn-on electric field at 10 μA/cm² from 1.064 to 0.774 V/μm and threshold field at 10 mA/cm² from 1.628 to 1.418 V/μm, respectively. Moreover, the stability behavior of the CNT arrays is ameliorated at or after suffering to temperatures. Raman, EDS, XPS, and photoelectron spectrometer were employed to characterize the CNT arrays before and after the FE-Temperature measurements for comparison. Our results demonstrate that the oxygen desorption induced work function decrease (from 4.89 to 4.68 eV) of the CNT arrays after longtime exposure to temperature is responsible for the improved FE behavior, while the annealing of defects on CNTs is the main reason for the improved FE stability, which provides an effective approach to stabilizing emitters by temperature processing.

[en] Porous Co₃O₄ with different structures have been synthesized by annealing cobalt-based metal–organic framework (Co-MOF) parallelepiped microcrystals. The transformation process of nanostructures at different temperatures has been investigated, which involves the depletion of Co-MOF core, formation, and crystal growth of cobalt oxide shell. Porous hollow parallelepipeds and microsheets can be obtained at 400 and 500 °C, respectively. When evaluated as electrode materials for supercapacitors, Co₃O₄ hollow parallelepipeds exhibit better electrochemical performances compared to Co₃O₄ microsheets, which can be attributed to the unique 3D hierarchical hollow structure and small particle size.