[en] Highly ordered ultrafine nanostructures (feature size <10 nm) have been successfully fabricated with single-nanometre precision using a convergent electron beam (CEB) in a high-resolution transmission electron microscope (HRTEM). This approach can be widely applied to inorganic solid-state materials including insulators, semiconductors and metals. The feature size can be precisely controlled by the probe size and the irradiation time. The formation mechanism of nanostructures fabricated by CEB has been discussed in terms of knock-on damage and the beam heating effect. On the basis of the experimental results of electron energy-loss spectroscopy (EELS), finite element thermal analysis reveals that the heating effect of the high-energy electron beam is negligible in inorganic solid-state materials, and the sculpting of nanostructures is predominated by the knock-on damage or ionization of high-energy electrons

[en] Under investigation the heap leaching technology of one uranium ore, the main reason for its long heap leaching period is analyzed. First, the granularity of the heap leaching ore is large, which reduces the diffusion rate and increases the leaching period. Second, the content of impurities in the leaching agent is too much, which reduces its ability to dissolve minerals. Third, the spray system is unreasonable, which affects the permeability and heap leaching effect of the ore. Therefore, the tests on effects of ore granularity, spray acidity and operating conditions on leaching efficiency were studied, and the countermeasures to shorten the leaching period were put forward. (authors)

[en] Ammonia nitrogen in some uranium-containing wastewater exceeds standard and needs to be discharged after treatment. By studying the influence of different temperature, pH value, concentration of dissolved oxygen and concentration of uranium on the activity of nitrifying bacteria, the application possibility of nitrifying bacteria in wastewater containing uranium and high ammonia nitrogen was discussed. And the simulation experiment of wastewater treatment was designed to verify the results. Experimental results show that nitrifying bacteria can grow at 5 ∼ 35℃, but at different rates. The dissolved oxygen concentration of 0.8 mg/L had no effect on the growth of nitrifying bacteria, but the uniformity of the solution would affect the efficiency of ammonia nitrogen degradation. The pH value has the greatest influence on nitrifying bacteria. When the pH value is lower than 7, its growth rate will decrease with the decrease of pH value. 0.1 ∼ 0.3 g/L of uranium has a weak effect on the growth of nitrifying bacteria, and it's very obvious at 0.4 g/L. In simulated wastewater treatment, low-concentration uranium had no negative effect on nitrifying bacteria. When the concentration of ammonia nitrogen reached 550 mg/L and the speed was 2.6 L/d, the effluent still reached the standard. Experiments show that nitrifying bacteria can be used in the treatment of wastewater containing uranium and high ammonia nitrogen as long as the pH value of the solution is controlled well. (authors)

[en] The influence factor on efficiency of ¹⁸F-FDG is investigated with '2-pot' system to improve the yield of ¹⁸F-FDG. The synthesis efficiency is leaded to low in evidence by water in synthesis system which it comes from K2.2.2 or acetonitrile of delivered tube. The lower impurity of recovery H₂¹⁸O also lead to low yield. The Triflate more than 15 mg can accord with operating requirement. The shortened synthesis time will benefit to EOS. The synthesis time shorten from 55 min to 44 min, EOB can be increased from 50% to 65% by optimized synthesis time and controlled less water in synthesis

[en] The composition of a volcanic type uranium ore is complex, total content of calcium, magnesium and aluminum is 15.48%. The main acidic consumption minerals are chlorite, calcite and apatite. Conventional agitation leaching experimental results show that when acid usage content is 25%, and spent acid concentration in the leached solution is 82.5 g/L, the content of uranium in the leached tailing is reduced to 0.013%, and leaching rate is 89%. But the uranium leaching rate is only 72% by alkaline pressure leaching. By the uranium ore characteristics which need higher spent acid concentration to decompose apatite, two stage countercurrent agitation leaching experiment was carried. Compared with conventional agitation leaching experimental result, two stage countercurrent agitation leaching experiment can save 26% of acid. (authors)

[en] Bioleaching experiment of a low grade uranium ore was carried out. The results show that the leaching effect of uranium by bacteria was obviously better than that by conventional acid leaching. The leaching strains are aerobic bacteria, but it only needs a small amount of oxygen to survive. Under the anoxic condition, bacteria can also attach and grow in the ore pillar and oxidize ferrous rapidly. The results can provide a basis for the feasibility of bioleaching in underground heap construction. (authors)

[en] According to the mineralogical characters and chemical composition of a copper uranium ore, the experiments of acid agitation leaching and column leaching have been carried out in order to explore the optimum conditions of ore treatment. The results show that, by acid agitation leaching the leaching rate of uranium is up to 96.3% while copper is 40.2%; by column leaching the leaching rate of uranium is up to 94.4% and copper is 63.6%. Recommended heap leaching technology parameters for recovering uranium and copper from the ore are that ore granular size is -10 mm, pyrolusite amount is 2% (ratio to ore mass), sulfuric acid concentration is 30 g/L, spraying intensity is 20 L/(m²·h) and ratio of sparying to pausing is l : 1. (authors)

[en] An experimental investigation is reported on in situ encapsulating copper nanoparticles with a nanolayer of hydrocarbon coating. Copper nanoparticles produced by the flow-levitation method are in situ encapsulated by the dielectric barrier discharge, which generates carbon and hydrogen plasmas for forming a polymerized nanolayer of hydrocarbon at the surface of Cu nanoparticles. The structural, chemical components and optical properties of the encapsulated Cu nanoparticles are characterized by transmission electron microscopy, energy dispersive x-ray spectra, x-ray diffraction, x-ray photoelectron spectra, and UV-visible absorption

[en] We studied the influence of adsorbates on the space-charge-limited current (SCLC) in individual ZnO nanowires through varying the bias voltage, laser illumination, and ambient pressure. In dark and air conditions, the free carriers were depleted by the surface adsorbates, and electrons injected from the electrode to the nanowire dominated the electron transport properties. Under laser illumination, the current-voltage characteristic was linear at low voltage and superlinear at high voltage, and the SCLC regime occurred at high voltages due to the surface desorption. The time response of photoconductivity further revealed the dynamic process of elimination of SCLC by desorption of oxygen molecules at the ZnO nanowire surface

[en] The controllable deformation of nanopores was realized by moving a convergent electron beam in a high-resolution transmission electron microscope. Nanostructures with the desired geometries were successfully fabricated from the original nanopores in 100 nm-thick and 260 nm-thick Si₃N₄ membranes. The formation dynamics is a competition process between the knock-on effect of the high-energy electron beam and surface tension driven shrinkage. This approach can be used to finely tune critical dimensions and deform nanopores to particular desired geometries with single-nanometer precision, which offers substantial opportunities in flexibly fabricating nanostructures for various applications such as nanoelectronics and nanofluidics.