Effects of longitudinal fire source locations on the maximum temperature and longitudinal temperature decay in a mountain tunnel with vertical shaft: an experimental investigation and empirical model

Journal of Thermal Analysis and Calorimetry - Few investigations have focused on the influence of longitudinal fire source location on the temperature profile of smoke induced by fire in a tunnel...     

饲料中激素类药物及其检测技术研究进展

综述了饲料中常用激素类药物的现状及分析技术。对激素类药物的种类、化学特性,应用情况及危害性进行了分析,对饲料中激素类药物残留的前处理和检测方法进行了介绍。重点研究关注了激素类药物和分析方法的异同,从而了解和掌握该领域发展动态,为建立健全相关的限量标准和检测方法提供参考。     

High-throughput Synthesis of Solution-Processable van der Waals Heterostructures through Electrochemistry

Two-dimensional van der Waals heterostructures (2D vdWHs) have recently gained widespread attention because of their abundant and exotic properties, which open up many new possibilities for next-generation nanoelectronics. However, practical applications remain challenging due to the lack of high-throughput techniques for fabricating high-quality vdWHs. Here, we demonstrate a general electrochemical strategy to prepare solution-processable high-quality vdWHs, in which electrostatic forces drive the stacking of electrochemically exfoliated individual assemblies with intact structures and clean interfaces into vdWHs with strong interlayer interactions. Thanks to the excellent combination of strong light absorption, interfacial charge transfer, and decent charge transport properties in individual layers, thin-film photodetectors based on graphene/In₂Se₃ vdWHs exhibit great promise for near-infrared (NIR) photodetection, owing to a high responsivity (267 mA W⁻¹), fast rise (72 ms) and decay (426 ms) times under NIR illumination. This approach enables various hybrid systems, including graphene/In₂Se₃, graphene/MoS₂ and graphene/MoSe₂ vdWHs, providing a broad avenue for exploring emerging electronic, photonic, and exotic quantum phenomena.     

Easily Scalable Shell-Structured Copper Catalyst with High Activity and Durability for Carbon Dioxide Hydrogenation

Inducing strong metal-support interaction (SMSI) has been a useful way to control the structure of surface active sites. The SMSI often causes the encapsulation of metal particles with an oxide layer. Herein, an amorphous ceria shell was formed on Cu nanoparticles under a mild gas condition with high activity and durability for surface reaction. Cu−Ce solid solution promoted the transfer of surface oxygen species, which induced the ceria shell formation on Cu nanoparticles. This catalyst was used for CO₂ hydrogenation, selectively producing CO with high low-temperature activity and good durability for operation at high temperature. CO₂ activation and H₂ spillover could occur at low temperatures, enhancing the activity. The shell prevented the sintering, assuring durability. This catalyst was applied to a bench-scale reactor without loss in performance, resulting in high CO productivity in all temperature ranges.     

Solitons supported by defects of PT-invariant potentials with real part of dual-frequency lattices

The existence and stability of defect solitons in defective PT potentials with real part of dual-frequency lattices are reported. For positive defects, fundamental solitons are always stable in the semi-infinite gap and nonexistent in the first gap. While for negative defects, in the semi-infinite gap, fundamental solitons are stable in most of their existence region apart from low power region, but all the fundamental solitons are stable in the first gap. Dipole solitions are unstable in the whole semi-infinite gap regardless of defects, but in the first gap they can be stable in the low power region for positive defects.     

低温胁迫下PQQ对黄瓜幼苗子叶防御系统的影响

报道了低温胁迫下吡咯喹啉醌（ＰｙｒｒｏｌｏｑｕｉｎｏｌｉｎｅＱｕｉｎｏｎｅ，ＰＱＱ）对黄瓜幼苗子叶超氧化物岐化酶（ＳＯＤ），抗坏血酸过氧化物酶（ＡｓＡＰＯＤ）和谷胱甘肽（ＧＳＨ）含量的影响，并与常规的外源活性氧清除剂８－羟基喹啉（８－ＨＱ），抗坏血酸（ＡｓＡ）进行了比较．结果表明，ＰＱＱ能提高ＳＯＤ，ＡｓＡＰＯＤ活性，增加ＧＳＨ含量．缓解电解质泄漏，减缓质脂过氧化作用．ＰＱＱ可作为活性氧清除剂，调节生物体内自由基代谢平衡，提高植物的抗逆性．     

高效液相色谱-串联质谱法同时测定食用油中的16种抗氧化剂

利用高效液相色谱-串联质谱(HPLC-MS/MS)同时测定食用油中16种抗氧化剂。食用油中的抗氧化剂经正己烷溶解、含L-抗坏血酸棕榈酸盐的乙腈萃取后,经C18柱分离,乙腈-0.1%甲酸溶液体系为流动相进行梯度洗脱,多反应监测模式(MRM)检测,外标法定量。16种抗氧化剂呈良好的线性关系(r~2=0.9912~0.9988),方法的测定低限为0.1~0.5mg/kg,在测定低限浓度水平下的平均回收率为78.6%~101.2%,相对标准偏差为3.50%~13.19%(n=10)。该方法准确、灵敏、重现性好,可用于食用油中16种抗氧化剂的检测。     

高效液相色谱-串联质谱法同时测定饲料中11种霉菌毒素

建立了高效液相色谱-串联质谱(HPLC-MS/MS)同时检测饲料中11种霉菌毒素的分析方法。样品经乙腈提取,MycoSep 228多功能净化柱填料和PRIME HLB固相萃取柱净化;采用Agilent Zorbax SB-C18色谱柱(150 mm×2.1 mm,3.5μm)分离,以甲醇和5 mmol/L乙酸铵水溶液(含0.1%(v/v)甲酸)为流动相梯度洗脱;采用ESI源正、负离子同时扫描,多反应监测(MRM)模式测定,内标法定量。结果表明,11种目标物在各自的线性范围内线性关系良好,相关系数均大于0.99,定量限为2.0~50.0μg/kg。11种霉菌毒素在3个加标水平(1、2、5倍定量限)下的平均回收率为79.3%~101.6%,相对标准偏差(RSD)为5.9%~13.2%(n=5)。该法简单快速,净化效果好,灵敏度高,适用于饲料中11种霉菌毒素的分析。     

气相色谱–串联质谱法快速测定茶叶中的蒽醌

建立气相色谱–串联质谱法(GC–MS–MS)快速测定茶叶中蒽醌的方法。样品中的蒽醌用色谱纯乙腈提取,经过涡旋1 min,超声20 min,离心、浓缩后用固相萃取柱(SPE)净化,以DB–5MS毛细管柱分离,以m/z 207.9,152为定性离子对、m/z 207.9,180为定量离子对,多反应检测模式下测定,外标法定量。蒽醌的质量浓度在1~500μg/L范围内与定量离子的峰面积呈良好的线性关系,相关系数为0.999 98,方法的检出限为1μg/kg。在10,20,50μg/kg加标水平下,样品加标回收率为92.85%~98.10%,测定结果的相对标准偏差为8.50%~11.05%(n=5)。该方法简单、快速,检出限低,准确度和精密度高,可用于茶叶中蒽醌的检测。     

水下多层均匀材料的声特性

本文研究水和空气中由不同厚度的两层弹性板及消声橡胶共同组成的分层介质在斜入射时的声特性,并采用数值方法求解多层结构声场的线性方程组。得到反射,透射系数,当板的厚度远小于波长时,采用弹性薄壳振动模型和弹性波模型进行计算,它们的结果基本相同,但是薄壳振动模型更便于计算和理论分析;对系统反射系数和透射系数的计算结果表明,系统增加消声橡胶层后,极大地改变后射系数和透射系数的频率响应;频率升高,反射系数减小