Photoactive Earth‐Abundant Iron Pyrite Catalysts for Electrocatalytic Nitrogen Reduction Reaction

The generation of ammonia, hydrogen production, and nitrogen purification are considered as energy intensive processes accompanied with large amounts of CO₂ emission. An electrochemical method assisted by photoenergy is widely utilized for the chemical energy conversion. In this work, earth‐abundant iron pyrite (FeS₂) nanocrystals grown on carbon fiber paper (FeS₂/CFP) are found to be an electrochemical and photoactive catalyst for nitrogen reduction reaction under ambient temperature and pressure. The electrochemical results reveal that FeS₂/CFP achieves a high Faradaic efficiency (FE) of ≈14.14% and NH₃ yield rate of ≈0.096 µg min^?1 at ?0.6 V versus RHE electrode in 0.25 m LiClO₄. During the electrochemical catalytic reaction, the crystal structure of FeS₂/CFP remains in the cubic pyrite phase, as analyzed by in situ X‐ray diffraction measurements. With near‐infrared laser irradiation (808 nm), the NH₃ yield rate of the FeS₂/CFP catalyst can be slightly improved to 0.1 µg min^?1 with high FE of 14.57%. Furthermore, density functional theory calculations demonstrate that the N₂ molecule has strong chemical adsorption energy on the iron atom of FeS₂. Overall, iron pyrite‐based materials have proven to be a potential electrocatalyst with photoactive behavior for ammonia production in practical applications.     

Effects of hydroxyl radical induced oxidation on water holding capacity and protein structure of jumbo squid (Dosidicus gigas) mantle

Protein oxidation is considered as an important issue in food preservation process. In the present study, the potential influence of protein oxidation on water holding capacity and protein structure of jumbo squid (Dosidicus gigas) mantle was investigated. After the hydroxyl radical oxidation, it was found that the carbonyl, surface hydrophobicity and dityrosine content of myofibrillar protein significantly increased (P < 0.05), while the content of total sulphydryl decreased significantly (P < 0.01). Meanwhile, the fluorescence intensity of squid was weakened, and the maximum absorption peak of fluorescence red shift as the H₂O₂ concentration increased. The sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) showed that not only the protein cross-linking but also degradation could have occurred. The content of α-helix decreased, the content of β-sheet, β-turn and the unordered structures increased after oxidation. In addition, oxidation resulted in a decrease in water holding capacity. Taken together, oxidation resulted in the damage of the myofibrillar structure, the increase in muscle loss rate and the decrease in water holding capacity.     

最优化算法与纯元素谱剥离相结合的能量色散X射线荧光谱解谱方法

在进行能量色散X射线荧光光谱(EDXRF)解谱时,如果给定样品的元素构成,采用纯元素谱图剥离的方式会更加合理,但由于每个元素的谱线都不止一条,如果仅仅针对主线对齐做剥离,会导致结果的严重失真,同时剥离次序对解谱结果有较大影响。介绍了一种最优化算法与纯元素谱剥离相结合的EDXRF解谱方法,该方法以多个纯元素谱的强度大小和峰位漂移道数作为变量构建残差方程,并用最优化计算的方法去调整,直至残差达到极小。实验采用强度顺序剥离、能量顺序剥离和最优化算法拟合3种方法分别对谱线重叠较为严重的La-Ce-Pr-Nd混合液样品的L系谱线进行了解析,结果表明最优化计算方法拟合的谱图与原始谱的残差 (1415.0)比另两种方法(166094.0和3192.7)大幅度缩小,拟合谱与原始谱更为吻合,并且方法在实现时对初值不敏感,解谱精度也不依赖于剥离次序。     

Fenton 絮凝工艺去除废水中的有机物试验

为了研究废水中有机物的去除问题，针对某企业含有机物废水进行了对比试验，采用了Fenton 絮凝联合工艺去除废水中的COD（化学需氧量）和浊度，考察了初始pH值、H2O2投加量、H2O2与Fe2+投加物质的量比、反应时间、絮凝剂投加量以及絮凝剂投加时的pH值对COD以及浊度去除效果的影响。结果表明，采用最佳工艺参数组合后，浊度去除率和COD的去除率分别为99.32%和97.27%。     

Stabilizing temperature-capacitance dependence of (Sr,Pb, Bi)TiO3-Bi4Ti3O12 solutions for energy storage

(1-x)Sr_0.7Pb_0.15Bi_0.1TiO₃-xBi₄Ti₃O₁₂ ((1-x)SPBT-xBIT, x = 0-0.125) bulk ceramics were developed and calcined via the solid-state method, aimed at the application of pulsed power capacitors. The phase structures, temperature stability, hysteresis loop, and discharge properties were systematically investigated. Considering both the temperature stability and dielectric properties, 0.925SPBT-0.075BIT bulk ceramics with a capacitance variation satisfying the X7R specification were developed for pulsed power capacitors. The energy storage density was 0.252 J/cm³, and the ceramics showed high temperature stability at 80 kV/cm. The discharge current waveforms of the 0.925SPBT-0.075BIT ceramics were recorded. A high discharge power density of approximately 1.01 × 10⁸ W/kg with an 8 Ω load resistor and short discharge period of 84 ns were achieved at 50 kV/cm. The good temperature stability properties and high power density show that the 0.925SPBT-0.075BIT ceramics are well suited for pulsed power capacitors with a wide temperature range.     

重水浓度与吸光度关系曲线类型研究

重水作为反应堆的慢化材料，其浓度直接影响反应堆的安全和性能。为研究其重水浓度与吸光度间的关系曲线类型，基于朗伯-比尔定律，从理论上推导出液态重水中某种水分子的红外吸收峰分别与0~2种其他水分子的红外吸收峰发生重叠时重水浓度与吸光度间的关系式，分情况对二者之间的关系曲线类型进行讨论。采用傅里叶变换红外光谱仪，测得浓度为0.015%~99.98%（摩尔比）的重水标准样品吸收光谱，对重水浓度和吸光度间的关系曲线类型进行验证，理论推导与实际吻合。研究表明，一般情况下，宽浓度范围内，重水浓度与吸光度间的关系曲线类型为二次曲线；窄浓度范围内，关系曲线类型为线性。特殊情况下，吸光度为定值或关系曲线类型为线性。     

中厚板减薄过程残余应力的演变行为

 针对中厚板使用过程中的变形行为，研究了中厚板因减薄引起横向残余应力重新分布规律。基于剥层法理论建立了中厚板减薄过程中残余应力分布模型和挠曲变形模型，应用有限元分析法模拟了厚板减薄过程。对比分析了残余应力分布形式和中厚板挠曲变形程度的计算结果和有限元仿真模拟结果，验证了两种分析方法的可行性，并进一步分析了应力分布状态及厚板减薄方式对薄板减薄过程变形的影响。结果表明，两种分析结果都能反映中厚板减薄变形特征，但有限元仿真模拟方法能够随薄板减薄而改变中厚板约束状态，结果更为准确；中厚板内部原始残余应力分布状态及使用过程减薄方式对其减薄过程变形有重要影响，为中厚板的合理生产设计和使用提供理论依据。     

补偿强反光体表面红外测温误差的算法研究

针对运动强反光体表面温度实时测量困难、精度低这一难点,本文从红外测温原理入手,分析并揭示了红外测温精度易受到被测物体反射率、测量距离、测量环境、红外入射角等因素的影响。根据铝板材加工设备轧辊表面测温实际需要设计了一种利用红外传感器实现对强反光体表面温度点对点测量的方案。通过对测量数据的研究分析建立了一种基于斯忒藩定律的红外入射角度补偿算法,以此减小因红外入射角度变化产生的测温误差。实验结果证明本方法能较好地弥补红外入射角度变化产生的测温误差,提高测温精度。该补偿算法运算简单,适应性强,为改善入射角度变化对测温精度影响提供了新的方法。