不同铁基合金助剂熔渗法制备PDC及其烧结形貌

在高温高压条件下(5.6GPa,1400℃),以不同铁基合金(Fe55Ni26Mn14Co5、Fe55Ni26Co19、FeNi36)为烧结助剂(熔渗质),采用高压熔渗技术制备了金刚石复合片(PDC)。采用扫描电子显微镜(SEM)观察了PDC的烧结组织形貌,对铁基合金的熔渗机制进行了探讨。实验结果表明,三种合金能够均匀渗透金刚石层,与金刚石颗粒形成了致密交错的网状结构,PDC结合界面复合牢固。腔体的压力差(δP)和温度梯度即为合金熔渗的驱动力。     

轮作与连作对烤烟不同生育期根际土壤细菌群落结构的影响

为明晰烤烟连作是否对根际细菌群落结构产生影响,采集不同生育时期的轮作和连作烤烟根际土壤,运用 454焦磷酸测序技术,对根际土壤细菌 16S rDNA V1-V3片段序列结构组成进行分析。结果表明,与轮作处理相比,连作处理烤烟根际酸杆菌门丰度在生育前期低而在后期高,但 α-变形菌门和放线菌门表现出相反的变化趋势;烤烟连作降低了表征菌群丰度的 Chao指数和物种丰富度的 Shannon指数,表明烤烟连作降低了根际土壤细菌多样性。主成分分析和 NMDS(non-metric multidimensionalscaling)的聚类分析结果显示不同处理烤烟根际细菌群落结构随生育期而迁移,轮作与连作烤烟根际土壤细菌群落结构差异在生育前期体现明显,生育后期不明显,表明生育期是影响烤烟根际细菌群落结构变化的主要因素,而连作与轮作是次要因素。      

Effect of long-term overcharge and operated temperature on performance of rechargeable NiMH cells

In this article, sub-C size cylindrical NiMH cells were constructed for the performance investigation under long-term overcharge and elevated temperatures. The influence of operated conditions on cell performance and electrode materials was examined. The experimental results revealed that the NiMH cells had good tolerance for 1-month overcharge at a 0.2C rate, remaining the capacity and capacity-rate performance and showing promise as a candidate for backup power sources. However, the sub-C size NiMH cells did not exhibit good performance at elevated temperatures, and the cycling stability with 100% DOD (depth of discharge) at temperature of >50 °C is necessary to be further improved. The deterioration of electrochemical capacity and cycling stability at elevated temperatures was analyzed and the reasons were discussed.     

土茯苓中鞣质提取工艺的优化

为了提高土茯苓的应用价值,对土茯苓中鞣质的提取工艺进行了探究.以丙酮溶液作为提取剂回流提取,采用络合滴定法测定鞣质的提取量,通过单因素实验和正交实验对土茯苓中鞣质的提取工艺进行优化,并采用精密度实验、重复性实验以及加标回收率实验对方法进行了评价.结果表明,最佳提取工艺为：提取温度70℃、丙酮浓度40％、料液比1：15（g：mL）、提取时间90 min.在此条件下,土茯苓中鞣质的提取量为20.77 mg·g-1.该提取工艺经济可行,方法的精密度高、重现性好.     

高校人才资源管理探讨

人才问题是国家之间竞争核心问题之一,也是高校改革与发展的核心问题之一,高校的成功关键在于人,在于那些具有敬业精神和创新精神的教学人才、科研人才及管理人才。文章主要阐述了高校人才资源管理存在的问题,分析了高校人才资源管理的目的,提出了高校人才资源管理的策略与措施。     

硫掺杂TiO2/Ti光电极制备及其可见光光电催化性能

为了提高TiO2/Ti光电极在可见光下的光电催化活性,采用阳极氧化法制备了一种新型的硫掺杂TiO2/Ti光电极.采用扫描电子显微镜、X射线衍射、X射线荧光光谱等技术对光电极进行了表面形貌、结晶形态、晶粒尺寸、硫的掺杂量和价态以及吸光性能表征.研究表明:硫掺杂TiO2/Ti光电极的最佳制备条件为:成膜电压160V、电流密度100mA/cm2、Na2SO3质量浓度750mg/L;所制备的光电极具有良好的光电催化氧化降解邻苯二甲酸二甲酯活性,并能有效地矿化其中间产物;与TiO2/Ti电极相比,硫的掺杂可以显著提高其在可见光下的光电催化性能.     

Electronic and optical properties of orthorhombic LiInS2 and LiInSe2: A density functional theory investigation

The structural, electronic and optical properties of two orthorhombic crystals, LiInS₂ and LiInSe₂, were calculated using the density functional theory. The optimized unit cells are in good agreement with experimental data. It is shown that the two crystals belong to the semiconductors with a direct energy band gap of about 3.17 eV for LiInS₂ and 2.63 eV for LiInSe₂. The important structural character of the two compounds is that there is a strong hybridization between In-5s, 5p orbits and S-3p (Se-4p) orbits at upper valence bands. The fundamental understanding on how the different anion (Se and S) affects the electronic and optical properties of the two crystals was highlighted in our calculations. The optical properties include the dielectric spectra, absorption, reflectivity and energy-loss spectra, and the origin of spectral peaks were analyzed based on the electronic structures. The results indicate that the two compounds are promising IR crystal materials.     

镀液中氨基磺酸镍质量浓度对电镀镍层析氢催化活性的影响

采用由10 g/L NiCl₂·6H₂O、30 g/L NH₄Cl和310～390 g/L Ni(NH₂SO₃)2·4H₂O(氨基磺酸镍)组成的镀液(pH=3.8),在温度35°C和电流密度3 A/dm²的条件下电镀30 min,获得镍电极。研究了镀液中氨基磺酸镍质量浓度对镍镀层表面形貌和析氢催化活性的影响。结果表明,镀液中氨基磺酸镍质量浓度为350 g/L时,镍镀层结晶最细致,析氢催化活性和稳定性最佳。     

A novel cobalt–free La0.5Ba0.5Fe0.95Mo0.05O3–δ electrode for symmetric solid oxide fuel cell

Cobalt − free perovskite oxide La_0.5Ba_0.5Fe_0.95Mo_0.05O_3−δ (LBFMo) was investigated as the electrode of symmetric solid oxide fuel cell (S − SOFC) based on 300−um − thick La_0.9Sr_0.1Ga_0.8Mg_0.2O_3−δ (LSGM) electrolyte. The electrochemical performance of the S − SOFC with LBFMo|LSGM|LBFMo configuration was evaluated using ambient air as oxidant and H₂ as fuel. The maximum power density (P_max) of the S − SOFC achieves as high as 0.96 W cm⁻² at 800 °C; meanwhile, the total polarization resistance (R_pt) of the S − SOFC (including the contributions of both cathode and anode) is only ∼0.12 Ω cm². Impedance spectra analysis indicates the polarization associated with anode plays a more rate − limiting role in the whole electrochemical reaction process of the S − SOFC. In addition, using LBFMo as symmetric electrode, the S − SOFC also exhibits good cell stability. All results indicate that the LBFMo is a very potential candidate for S − SOFC electrode.     

食用菌活性成分抗氧化机制的研究进展

细胞氧化会带来衰老与疾病,作为天然抗氧化剂来源的食用菌因富含多糖、三萜及酚类等活性成分,具有极大的开发潜力与药用价值。但食用菌中发挥抗氧化活性成分的构效关系尚不明确,其抗氧化成分是否围绕Kelch样环氧氯丙烷相关蛋白-1(Kelch like epichlorohydrin associated protein 1, Keap1)-核因子E2相关因子2(nuclear factor erythroid-2-related factor 2, Nrf2)-抗氧化反应元件(antioxidant response element, ARE)和磷脂酰肌醇-3激酶(phosphatidylinositol-3-kinase, PI3K)-蛋白激酶B(protein kinase B, Akt)-Nrf2途径发挥活性尚不清晰,阻碍了食用菌的开发与利用。因此,本文围绕自由基清除、Fe²⁺氧化还原反应及酶活防御能力等抗氧化评价指标,综述近年来食用菌活性成分抗氧化机制,分类分析食用菌活性成分的组成与结构对抗氧化活性的影响,提出食用菌抗氧化成分挖掘领域亟待解决的科学问题,旨在为食用...