三角形石墨烯纳米片电子和磁学性质的尺寸效应

基于密度泛函理论, 本文研究了氢钝化锯齿形边缘三角形石墨烯纳米片的电子结构和磁学性质, 这种石墨烯纳米结构的基态表现出强烈的磁性边缘态和量子尺寸效应。 我们应用多种交换关联泛函, 对体系的自旋密度和电子结构进行了第一性原理计算和理论分析, 结果表明三角形石墨烯纳米片的总磁矩和自旋随尺寸线性变化,平均磁矩随着尺寸变大而增加, 并逐渐趋于一个定值。 与此同时, 体系的能隙随着尺寸增加而减小, 其中自旋不变能隙的调控对光学响应和光子激发有着重要意义。 计算得到的单电子能谱表明, 费米能级的简并度与体系尺寸成正比。 应用多种交换关联泛函的计算结果表明, 三角形石墨烯纳米片具有可调控的自旋和能隙, 为其在纳米级光电器件和磁性半导体的应用方面提供了理论依据.     

Synergistic Interplay of Dual-Active-Sites on Metallic Ni-MOFs Loaded with Pt for Thermal-Photocatalytic Conversion of Atmospheric CO2 under Infrared Light Irradiation

Infrared light driven photocatalytic reduction of atmospheric CO₂ is challenging due to the ultralow concentration of CO₂ (0.04 %) and the low energy of infrared light. Herein, we develop a metallic nickel-based metal–organic framework loaded with Pt (Pt/Ni-MOF), which shows excellent activity for thermal-photocatalytic conversion of atmospheric CO₂ with H₂ even under infrared light irradiation. The open Ni sites are beneficial to capture and activate atmospheric CO₂, while the photogenerated electrons dominate H₂ dissociation on the Pt sites. Simultaneously, thermal energy results in spilling of the dissociated H₂ to Ni sites, where the adsorbed CO₂ is thermally reduced to CO and CH₄. The synergistic interplay of dual-active-sites renders Pt/Ni-MOF a record efficiency of 9.57 % at 940 nm for converting atmospheric CO₂, enables the procurement of CO₂ to be independent of the emission sources, and improves the energy efficiency for trace CO₂ conversion by eliminating the capture media regeneration and molecular CO₂ release.     

Epidemic dynamics and spatial segregation driven by cognitive diffusion and nonlinear incidence

We propose susceptible-infected-susceptible epidemic reaction–diffusion models with cognitive movement and nonlinear incidence $S^q{I}^p$ $(p,q>0)$ in a spatially heterogeneous environment. The cognitive dispersal term takes either random diffusion or symmetric diffusion. Building upon the $L^{\infty }$-estimates of positive solutions under $p,q>0$, we state the asymptotic dynamics for , $q>0$. The numerical results reveal spatial segregation of susceptible and infected populations: (a) the heterogeneous random diffusion can segregate the population and reduce the infection fraction significantly; (b) the segregation phenomenon disappears as the ratio $p/q$ approaches one from below; (c) the disease-free region strengthens the segregation induced by heterogeneous random diffusion; (d) the segregation governed by random diffusion is more sensitive to the incidence mechanism; (e) the distribution of steady states driven by symmetric diffusion is always similar to that by homogeneous diffusion.     

有机光催化剂用于太阳能水分解：分子水平和聚集体水平改性

利用太阳能光解水产氢是实现氢能开发最绿色且可持续的理想技术。为了提高太阳能的转换效率，设计和发展高效、稳定、宽/全光谱响应光催化产氢体系成为关键研究课题。相比于无机半导体，有机半导体具有丰富的π电子和结构可修饰性，使其光学吸收和能带结构易剪裁，光催化路径多样。但低的介电常数造成其载流子迁移率低及迁移距离短。通过有目的地改变有机分子结构，可以轻松地设计和调控有机半导体的能带位置、增加摩尔吸光系数，改善材料对于整个太阳光谱中可见光或红外光的利用；通过功能分子微纳组装或集成，可进一步获得不同组分、维度(0维、1维、2维、3维)、尺寸、晶体学取向的有机光催化剂。有机微纳/复合结构的优异的比表面积、分子排布结构或能级排列结构可进一步提高太阳能的利用率和光生电荷的传输/分离效率，从而提高整体光电转换效率和产氢效率。然而，由于复杂的反应过程和设计困难，整个有机半导体的光催化物理化学过程仍不清楚。在这里，光催化的基本原理从光捕获、光激发电荷分离、表面反应的角度进行了讨论。随后详细总结了有机半导体纳米结构的制备方法包括超分子自组装、再沉淀法、气相沉积法以及其他方法。描述了典型的有机半导体材料，包括苝二酰...     

Hemin as a General Static Dark Quencher for Constructing Heme Oxygenase-1 Fluorescent Probes

The development of small-molecule probes suitable for live-cell applications remains challenging yet highly desirable. We report the first fluorescent probe, RBH, for imaging the heme oxygenase-1 (HO-1) activity in live cells after discovering hemin as a universal dark quencher. Hemin works via a static quenching mechanism and shows high quenching efficiency (>97 %) with fluorophores across a broad spectrum (λ_ex=400–700 nm). The favorable properties of RBH (e.g. long excitation/emission wavelengths, fast response rate and high magnitude of signal increase) enable its use for determining HO-1 activity in complex biological samples. As HO-1 is involved in regulating antioxidant defence, iron homeostasis and gasotransmitter carbon monoxide production, we expect RBH to be a powerful tool for dissecting its functions. Also, the discovery of hemin as a general static dark quencher provides a straightforward strategy for constructing novel fluorescent probes for diverse biological species.