具阶段结构的多时滞SIR模型的稳定性分析

考虑了一类具有两个阶段结构的SIR模型,得到了解的正性和有界性,通过分析特征方程根的分布,以T1和T2为参数分析了平衡点的稳定性和局部 Hopf 分支存在性.进一步地,利用规范型和中心流型理论,给出了决定Hopf分支方向和分支周期解的稳定性的隐式算法.最后利用一些数值模拟来支持所得到的理论分析结果.     

具阶段结构的多时滞SIR模型的稳定性分析

考虑了一类具有两个阶段结构的SIR模型,得到了解的正性和有界性,通过分析特征方程根的分布,以(?)_1和(?)_2为参数分析了平衡点的稳定性和局部Hopf分支存在性.进一步地,利用规范型和中心流型理论,给出了决定Hopf分支方向和分支周期解的稳定性的隐式算法.最后利用一些数值模拟来支持所得到的理论分析结果.     

Carbene‐Catalyzed Enantioselective Aromatic N‐Nucleophilic Addition of Heteroarenes to Ketones

The aromatic nitrogen atoms of heteroarylaldehydes are activated by carbene catalysts to react with ketone electrophiles. Multi‐functionalized cyclic N,O‐acetal products are afforded in good to excellent yields and optical purities. Our reaction involves the formation of an unprecedented aza‐fulvene‐type acylazolium intermediate. A broad range of N‐heteroaromatic aldehydes and electron‐deficient ketone substrates works effectively in this transformation. Several of the chiral N,O‐acetal products afforded through this protocol exhibit excellent antibacterial activities against Ralstonia solanacearum (Rs) and are valuable in the development of novel agrichemicals for plant protection.     

The effect of minor additions of P2O5 on some phase transformations of plate glass

The effects of additions of several tenths of a per cent of P₂O₅ on the devitrification behavior of plate glass with the primary phase of tridymite are different from that with the primary phase of wollastonite. But they still follow the phase equilibrium relationship of multicomponents. By examinations with TEM, and measurements of electrical resistivities, it is indicated that phase separation of plate glass may be promoted with a minor addition of P₂O₅. Through XPS measurements it is further suggested that such an addition causes a certain change in the structure of the plate glass.     

Dual-Site Activation Coupling with a Schottky Junction Boosts the Electrochemiluminescence of Carbon Nitride

Robust electrochemiluminescence (ECL) of carbon nitride (CN) requires efficient electron-hole recombination and the suppression of electrode passivation. In this work, Au nanoparticles and single atoms (Au_SA+NP) loaded on CN serve as dual active sites that significantly accelerate charge transfer and activate peroxydisulfate. Meanwhile, the well-established Schottky junctions between Au NPs and CN act as electron sinks, effectively trapping over-injected electrons to prevent electrode passivation. As a result, the porous CN modified with Au_SA+NP exhibits an enhanced and stable ECL emission, with a minimal relative standard deviation of 0.24 %. Furthermore, the designed ECL biosensor based on Au_SA+NP-CN shows a remarkable performance in detecting organophosphorus pesticides. This innovative strategy has the potential to offer new insights into strong and stable ECL emission for practical applications.     

PuO2颗粒对自发α射线的能量自吸收效应评估研究

构建PuO₂颗粒状α发射体的球体几何模型,采用蒙特卡罗和射程经验公式模拟计算α射线在PuO₂颗粒中的射程能量关系式及α射线从PuO₂颗粒表面出射的能谱分布,研究因PuO₂颗粒对自发α射线的能量自吸收效应导致的对人体内照射剂量评估的影响。研究结果表明,PuO₂粒径越大,其对自发α射线的能量自吸收效应越明显,内照射剂量的修正效果越好;当PuO₂粒径在2 μm以上时,内照射剂量的修正效果大于5%。本研究的结果对吸入放射性物质所致人体内照射剂量的准确估算有重要的参考价值,并可应用于放射性核素肿瘤治疗等领域的微剂量学研究。A sphere geometry model for plutonium oxide-based alpha emitter was setup.The range of alpha particle in plutonium oxide pellet versus its energy and the spectral distribution of alpha particle emerging from the emitter surface were calculated using Monte Carlo method combined with the empirical formula of range.The internal radiation dose resulted by self-absorption effect of α-rays emitted spontaneously in plutonium oxide was investigated accordingly.The result shows that the larger particle size the plutonium oxide-based alpha emitter has,the more obvious the self-absorption effect is and the better the correction effect of the intake absorbed dose that effects on human lung has.For plutonium oxide pellet with its particle size exceeding 2 μm,the correction quantity is expected to be larger than 5%.Our work is beneficial for a precise evaluation of internal radiation dose induced by inhaled radioactive material and microdosimetry study in radionuclide tumor therapy.     

有限图上首达时等随机变量的极限定理

1965年,Hammersley和Welsh在["Bernoulli 1713,Bayes 1763,Laplace 1813",1965,61-110]里提出了首达渗流模型.此后对该模型的研究主要集中于无限图,特别是整数格点Z~d上.近年来一些概率学家开始关注有限图上的首达渗流模型.有限图上首达渗流模型的关注点与无限图上有截然不同,主要涉及首达时、跳数、淹没时、直径等随机变量的极限行为.本文对于有限图上首达渗流模型的首达时等随机变量的极限定理进行了综述.     

Chemiluminescence and electrochemiluminescence applications of metal nanoclusters

Due to strong photoluminescence, extraordinary photostability, excellent biocompatibility, and good water-solubility, metal nanoclusters have attracted enormous attention since discovered. They are found to be novel fluorescence labels for biological applications and environmental monitoring. Recently the chemiluminescence (CL) or electrochemiluminescence (ECL) of metal nanoclusters has received increasing attention. This review covers recent vibrant developments in this field of the past 5 years, and highlights different functions of metal nanoclusters in various CL and ECL systems, such as luminophores, catalysts, and quenchers. Latest synthetic methods of metal nanoclusters used in CL or ECL are also summarized. Furthermore, we discuss some perspectives and critical challenges of this field in the near future.