Large-scale synthesis of single-crystal alpha manganese sesquioxide nanowires via solid-state reaction

Smooth single-crystal α-Mn₂O₃ nanowires have been fabricated using a one-step solid-state reaction method. X-ray diffraction patterns show that the nanowires have pure phase of α-Mn₂O₃. Transmission electron microscopy was employed to investigate the size and morphology of the products. The α-Mn₂O₃ nanowires exhibit mean diameter of 50 nm and length of 10 μm. Selected-area electron diffraction pattern demonstrates the single-crystal structure of the α-Mn₂O₃ nanowires, which are in good agreement with the X-ray diffraction results. The processes of the reactions and the phase transitions were also studied by using a simultaneous thermal gravimetric/differential thermal analyzer. It is found that the concentration of the precursor MnCO₃ is a crucial factor in the formation of the nanowires. This work provides the probability of the industrialization of fabricating smooth single-crystal α-Mn₂O₃ nanowires.     

寿胎丸加减方对超排卵小鼠种植窗期子宫内膜整合素β3蛋白表达的影响

目的探讨寿胎丸加减方对超排卵小鼠种植窗期子宫内膜整合素β3蛋白表达的影响。方法将70只昆明未孕小鼠按随机数字表法分为3组：中药组30只、阿司匹林组30只和对照组10只。建立控制性排卵小鼠模型。模型建立成功后,中药组、阿司匹林组、对照组分别给予寿胎丸加减中药、阿司匹林、0.9%氯化钠注射液进行干预。在小鼠种植窗期取子宫中段组织,采用免疫组化PV二步法检测子宫内膜组织中整合素β3蛋白的表达。结果中药组小鼠子宫内膜整合素β3蛋白强阳性表达率明显高于阿司匹林组和对照组,差异均有统计学意义（P〈0.05或P〈0.01）。阿司匹林组小鼠子宫内膜整合素β3蛋白强阳性表达率明显高于对照组,差异有统计学意义（P〈0.01）。结论寿胎丸加减方可提高超排卵小鼠种植窗期子宫内膜整合素β3蛋白的表达水平,改善子宫内膜的容受性。     

Analysis of composition, distribution and origin of hexachlorocyclohexane residues in agricultural soils from NW Spain

Concentrations of the isomers of the organochlorine pesticide hexachlorocyclohexane (HCH) were determined in 252 surface soil samples collected within a sampling network covering agricultural areas in Galicia (NW Spain). The concentration of total HCH (sum of α + β + γ + δ) ranged between 4 and 2305 ng g⁻¹ (dry weight), with the α-HCH and γ-HCH isomers predominating (< 1-1404 ng g⁻¹ and < 1-569 ng g⁻¹, respectively). The distribution of the pesticide residues was very heterogeneous, with the largest concentrations present in one of the studied areas (the province of A Coruña). The distribution of HCH was not found to be related to any soil property (organic matter, pH, clays, and metals). Multivariate statistical analysis of the data revealed that three populations of samples with a defined composition of HCH, can be related to the source of HCH: technical HCH (α/γ > 3), lindane (99% γ-HCH), or both. The existence of a third population consisting almost exclusively of α-HCH suggests that background contamination of anthropogenic origin dates from several decades ago. The detailed analysis of these populations enabled the possible temporal scale of the application of these pesticides to be deduced.     

Trend in criticality calculation results of borated-water-moderation experimental cores relating to 10B(n, α) cross section

ABSTRACT

In connection with the accuracy of the ¹⁰B(n, α) cross section in the thermal- and epithermal-neutron energy regions, criticality calculation results were examined for six benchmark sets of light-water-moderation critical experiments of UO₂ and MOX fuel lattice cores with un-borated and borated water. Two of the benchmark sets were those implemented in the Tank-Type Critical Assembly (TCA). The others were taken from the International Handbook of Evaluated Criticality Safety Benchmark Experiments (ICSBEP), and the International Handbook of Evaluated Reactor Physics Benchmark Experiments (IRPhEP). The enrichments of the UO₂ fuel range from 1.9 wt% to 2.6 wt%, and the Pu contents of the MOX fuel do from 2.0 to 6.6 wt%. The boron concentrations in water are up to 1511 ppm. The effective neutron multiplication factors (k_eff ) were taken from the published documents. They were calculated with continuous-energy Monte Carlo calculation codes in combination with JENDL-4.0, and other evaluated nuclear data libraries. It was confirmed that the k_eff values of the critical cores increased with the boron concentrations, which indicates that the ¹⁰B(n, α) cross section in the thermal- and epithermal-neutron energy regions should be larger than those in JENDL-4.0 and other libraries.     

阳江核电厂外围环境气溶胶总α、总β放射性水平

核电厂周围环境气溶胶的总放射性水平是一项重点关注项目。为掌握阳江核电周围环境气溶胶中总α、总β放射性水平及变化趋势,自2014年1月,对阳江核电厂5 km范围内大澳和允泊的气溶胶总α、总β进行为期三年的采样监测,获得该核电厂5 km范围内气溶胶总α、总β活度浓度范围分别为0.01-0.35 m Bq·m~(-3)、0.05-2.46 m Bq·m~(-3),年均值分别为0.07 m Bq·m~(-3)、0.65 m Bq·m~(-3)。受降雨影响,总α、总β放射性变化有明显的季节特征,总体呈现冬春季高、夏秋季低的特点。监测结果与对照点和本底调查进行比较,总α、总β活度浓度没有明显变化,初步判断阳江核电厂运行安全。     

α-Fe2O3@CNSs nanocomposites as superior anode materials for lithium-ion batteries

The nanocomposite of hematite@carbon nanosprings (α-Fe₂O₃@CNSs) was synthesized by simple precipitation and following heat treatment, in which the amount of α-Fe₂O₃ can be easily controlled by changing the synthesis conditions. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electronic microscopy (SEM), Brunau–Emmertt–Teller (BET), and X-ray photoelectron spectroscopy (XPS) were employed to characterize the as-synthesized nanocomposite. When applied as anode in Li-ion batteries (LIBs), the effect of α-Fe₂O₃/CNSs weight ratio on electrochemical performance of α-Fe₂O₃@CNSs nanocomposite has been researched. Enhancing the amount of α-Fe₂O₃ in nanocomposite would make the increase of specific capacity, but led to the degradation of cyclic stability and rate capability. The electrode of S-FeC (with weight ratio of CNSs/α-Fe₂O₃ about 4:1) could deliver a charge capacity of 527.6 mAh g⁻¹at 0.2 C with excellent cyclability (96.9% capacity retention after 50 cycles), and retained 343.3 mAh g⁻¹even at the rate of 5.0 C. In comparison with pure CNSs and α-Fe₂O₃, the improved cycling performance, specific capacity and rate capability of S-FeC should be mainly attributed to the combined effects of uniformly dispersed nanosized α-Fe₂O₃ particles and the highly strong network of CNSs.     

Cr(Ⅲ)络合物/MAO对催化乙烯齐聚选择性影响的研究

合成并表征了双(二苯基膦基)丙胺(Ligand 1)、双(二苯基膦)-2-(甲硫基)乙胺(Ligand 2)和双(二苯基膦)-3-(甲硫基)丙胺(Ligand 3)三种新型的配体。在助催化剂甲基铝氧烷(MAO)的作用下,上述配体与CrCl3(THF)3原位形成络合物催化乙烯齐聚。研究了反应温度、反应压力和n(Al)∶n(Cr)对其催化乙烯齐聚选择性的影响规律。研究结果表明:N取代基上引入S原子,使产物中1-己烯的选择性增大。对于Ligand 3/CrCl3(THF)3/MAO催化体系,当以环己烷为溶剂,反应温度为50℃、反应压力为3.0 MPa、n(Al)∶n(Cr)为300的反应条件下,催化活性可达25.4×104 g/(mol·h),其中1-C=6和1-C=8在液相中的总选择性可以达到91.9%。