阳离子交换皂石黏土在基质辅助激光解吸电离飞行时间质谱分析中的应用

将一种人工合成的无机聚合物——蒙脱石皂石黏土（smectite，Sm）应用于基质辅助激光解吸电离飞行时间质谱分析（matrix-assisted laser desorption/ionization time of flight mass spectrometry, MALDI-TOF-MS），以检测糖类化合物。 将传统的有机基质2，4，6-三羟基苯乙酮（trihydroxyacetophenone, THAP）与阳离子交换后的皂石黏土混合制备成新型复合基质，应用于糖类化合物的检测。通过比较不同的制样方法，测定不同分子直径的糖类化合物，发现由于受复合基质晶面间距的限制，只有小分子糖类化合物能进入晶面间隙充分接触有机基质并被离子化，从而实现对小分子糖类化合物的选择性检测。     

计算代数方程组孤立奇异解的符号数值方法

求解代数方程组是计算代数几何的最基本问题之一,孤立奇异解的计算则是其中最具挑战性的课题之一,在科学与工程计算中有着广泛的应用,如机器人、计算机视觉、机器学习、人工智能、运筹学、密码学和控制论等.本文结合作者的研究成果,综述了符号数值方法在计算代数系统孤立奇异解、特别是近似奇异解精化与验证方面的研究进展,并对未来的研究方向提出了展望.     

(Sm0.5Gd0.2Nd0.3)2(Hf0.3Ce0.7)2O7复合氧化物的热物理性能

为寻求新型热障涂层用陶瓷材料,本文采用高温固相烧结法制备了(Sm_0.5Gd_0.2Nd_0.3)₂(Hf_0.3Ce_0.7)₂O₇复合氧化物。利用XRD分析了其晶体结构,SEM分析其显微组织,膨胀仪测试其热膨胀性能,激光热导仪测试其热扩散系数。结果表明,成功制备了具有单一萤石晶体结构的(Sm_0.5Gd_0.2Nd_0.3)₂(Hf_0.3Ce_0.7)₂O₇复合氧化物。其显微组织结构致密,晶界清晰无其他相存在。由于复杂的元素组成和较大的原子量,其热导率明显低于7YSZ和Sm₂Ce₂O₇。其较低的热膨胀系数则归因于B位离子较小的离子半径,但其热膨胀系数依然满足热障涂层的要求。     

A general framework for describing photofission observables of actinides at an average excitation energy below 30 MeV

A reasonable prediction of photofission observables plays a paramount role in understanding the photofission process and guiding various photofission-induced applications, such as short-lived isotope production, nuclear waste disposal, and nuclear safeguards. However, the available experimental data for photofission observables are limited, and the existing models and programs have mainly been developed for neutron-induced fission processes. In this study, a general framework is proposed for characterizing the photofission observables of actinides, including the mass yield distributions (MYD) and isobaric charge distributions (ICD) of fission fragments and the multiplicity and energy distributions of prompt neutrons (n_p) and prompt γ rays (γ_p). The framework encompasses various systematic neutron models and empirical models considering the Bohr hypothesis and does not rely on the experimental data as input. These models are then validated individually against experimental data at an average excitation energy below 30 MeV, which shows the reliability and robustness of the general framework. Finally, we employ this framework to predict the characteristics of photofission fragments and the emissions of prompt particles for typical actinides including ²³²Th, ^{235, 238}U and ²⁴⁰Pu. It is found that the ²³⁸U(γ, f) reaction is more suitable for producing neutron-rich nuclei compared to the ²³²Th(γ, f) reaction. In addition, the average multiplicity number of both n_p and γ_p increases with the average excitation energy.     

Yield enhancement of elliptical high harmonics driven by bicircular laser pulses

We theoretically investigate the yield enhancement of elliptical high harmonics in the interaction of molecules with bicircular laser pulses by solving the time-dependent Schrödinger equation. It is shown that by adjusting the relative intensity ratio of the two bicircular field components in specific ranges the yield of the molecular high harmonics for the plateau and cutoff regions can be respectively enhanced. To analyze this enhancement phenomenon, we calculate the weights of the electron classical trajectories. Additionally, we also study the ellipticity distribution of harmonics for different intensity ratios. We find that these enhanced harmonics are elliptically polarized, which we mainly attribute to the recombination dipole moment of the major weighted trajectories. These enhanced elliptical extreme ultraviolet and soft x-ray radiations may serve as essential tools for exploring the ultrafast dynamics in magnetic materials and chiral media.     

Cu/CuO-Graphene Foam with Laccase-like Activity for Identification of Phenolic Compounds and Detection of Epinephrine

Although great progress has been made in the advancement of nanozymes, most of the studies focus on mimicking peroxidase, oxidase, and catalase, while relatively few studies are used to mimic laccase. However, the use of nanomaterials to mimic laccase activity will have great potential in environmental and industrial catalysis. Herein, Cu/CuO-graphene foam with laccase-like activity was designed for the identification of phenolic compounds and the detection of epinephrine. In a typical experiment, the formation mechanism of Cu/CuO-graphene foam was investigated during the pyrolysis process by thermogravimetric-mass spectrometry. As a laccase mimic, Cu/CuO-graphene foam exhibited excellent catalytic activity with a Michaelis-Menten constant and a maximum initial velocity of 0.17 mmol/L and 0.012 mmol∙L^-1∙s^-1, respectively. Based on this principle, Cu/CuO-graphene foam nanozyme could differentially catalyze phenolic compounds and 4-aminoantipyrine for simultaneous identification of phenolic compounds. Furthermore, a colorimetric sensing platform was fabricated for the quantitative determination of epinephrine, showing linear responses to epinephrine in the range of 3 mg/mL to 20 mg/mL with the detection limit of 0.2 mg/mL. The proposed Cu/CuO-graphene foam nanozyme could be applied for the identification of phenolic compounds and the detection of epinephrine, showing great potential applications for environmental monitoring, biomedical sensing, and food detection fields.