Ag10Ti28‐Oxo Cluster Containing Single‐Atom Silver Sites: Atomic Structure and Synergistic Electronic Properties

Supported single‐atom catalysts have been emerging as promising materials in a variety of energy catalysis applications. However, studying the role of metal–support interactions at the molecular level remains a major challenge, primarily due to the lack of precise atomic structures. In this work, by replacing the frequently used TiO₂ support with its molecular analogue, titanium‐oxo cluster (TOC), we successfully produced a new kind of Ti‐O material doped with single silver sites. The as‐obtained Ag₁₀Ti₂₈ cluster, containing four exposed and six embedded Ag sites, is the largest noble‐metal‐doped Ti‐O cluster reported to date. Density functional theory (DFT) calculations show that the Ag₁₀Ti₂₈ core exhibits properties distinct from those of metallic Ag‐based materials. This Ti‐O material doped with single Ag sites presents a high ?_d and moderate CO binding capacity comparable to that of metallic Cu‐based catalysts, suggesting that it might display different catalytic performance from the common Ag‐based catalysts, for example, for CO₂ reduction. These results prove that the synergism of active surface metal atoms and the Ti‐O cluster support result in unique physical properties, which might open a new direction for single‐atom‐included catalysts.     

An Intramolecular Charge Transfer and Aggregation Induced Emission Enhancement Fluorescent Probe Based on 2‐Phenyl‐1,2,3‐triazole for Highly Selective and Sensitive Detection of Homocysteine and Its Application in Living Cells

In this work, a new simple and readily synthesized turn‐on probe 2‐(4‐anthracene‐9‐yl‐phenyl)‐ 2H‐[1,2,3]triazole‐4‐carbaldehyde (APTC) was legitimately designed towards homocysteine (Hcy). Moreover, APTC has excellent optical properties such as intramolecular charge transfer (ICT) and aggregation induced emission enhancement (AIEE) characteristics, indicating its extensive application potentiality. What's more, APTC displayed rapid, high selectivity and specificity towards homocysteine over cysteine/glutathione. The detection limit of APTC for Hcy was as low as 2.198×10^–8 mol·L^–1, and the response time was only 5 min. APTC has been successfully applied to detect Hcy in silica gel plates and living cells, which indicates that APTC has good stability and biocompatibility as a selective probe for Hcy. Finally, the mechanism was studied using ¹H NMR titration experiments and mass spectrometry.     

Construction of C(sp2)−C(sp3) Bond between Quinoxalin‐2(1H)‐ones and N‐Hydroxyphthalimide Esters via Photocatalytic Decarboxylative Coupling

A novel visible‐light‐driven decarboxylative coupling of alkyl N‐hydroxyphthalimide esters (NHP esters) with quinoxalin‐2(1H)‐ones has been developed. This C(sp²)?C(sp³) bond‐forming transformation exhibits excellent substrate generality with respect to both the coupling partners. Of note, a series of 3‐primary alkyl‐substituted quinoxalin‐2(1H)‐ones that were difficult to synthesize by previous methods could be obtained in moderate to excellent yields. Additionally, the mild conditions, easy availability of substrates, wide functional group tolerance and operational simplicity make this protocol practical in the synthesis of 3‐alkylated quinoxalin‐2(1H)‐ones.     

基于单一分光棱镜干涉仪的双通路定量相位显微术

仅仅使用一个单独的分光棱镜(BS),实现了一种用于生物细胞三维成像的双通路定量相位显微术.不同于传统的使用方法,将BS倾斜放置,使中央半反射层与入射光光轴之间存在一个非常小的角度.这样基于BS的分光特性,经过BS后的透射光束和反射光束将会叠加在一起并形成干涉.调节样品位置,利用相机拍摄同时获得了存在π相移的双通路干涉图.这种离轴干涉模式,只需要记录单幅干涉图就可以获得真实的相位信息,方法结构简单,易于操作,适用于微小透明样品的三维形貌测量.     

一个改进的电磁波传输激波管实验

在中国科学院力学研究所$\varPhi $ 800 mm高温低密度激波管上进行电磁波在等离子体中传输机理研究时,低密度和强激波条件下,由于气体解离和电离等非平衡过程,使得激波后2区宽度显著减小;同时由于边界层效应造成激波衰减和接触面加速,使得激波后2区长度进一步减小.这两个效应导致激波管2区实验观测 时间减小,2区气体处于非平衡状态,增加了观察数据的不稳定性和数据分析的难度.本文提出在$\varPhi 800 $ mm高温低密度激波 管中采用氩气(Ar)和空气(Air)混合气替代纯空气作为激波管实验介质气体.利用Ar不解离和难电离的特性,减小激波前后压缩比,从而 增加激波后2区实验时间和气体长度. 采用Langmuir 静电探针和微波透射诊断技术测量激波后电子密度,同时利用探针测量激波后2区实验时间.结果显示,在Ar+Air混合气实验中,激波波后电子密度可达与纯Air同样的10$^{13}$cm$^{ - 3}$量级.在与纯Air相同的电子密度和碰撞频率条件下,采用95%Ar+5%Air和90%Ar+10%Air两种混合气,激波后2区实验时间和气体长度约为纯Air条件下的5$\sim $10倍,其中2区实验时间为300$\sim $800 $\mu$s,2区气体长度1$\sim $1.5 m.在$\varPhi $800 mm激波管中采用Ar+Air介质气体进行电磁波传输实验,获得了比在纯Air介质中与理论预测更一致的结果.      

Bifunctional Pancharatnam‐Berry Metasurface with High‐Efficiency Helicity‐Dependent Transmissions and Reflections

Manipulating circularly‐polarized (CP) waves in desired multi‐prescribed manners, especially in both transmission and reflection schemes, in a single flat device is of particular importance in photonic integration, imaging processing and communication systems. However, available approaches suffer from large thickness, low efficiencies as well as limited wavefront control spaces. Here, we propose a general strategy by using specially tailored Pancharatnam‐Berry (PB) meta‐atoms with helicity‐dependent transmissions and reflections to design high‐efficiency CP bifunctional metasurfaces. As a proof of the strategy, two metadevices are designed and characterized at microwave frequencies: the former one achieving focusing/diverging lenses at transmission/reflection side of the metasurface; the latter one realizing CP beam separation under illuminations of CP waves with different chirality, respectively. Both numerical and experimental results demonstrate the predicted EM functionalities, and all these functionalities exhibit very high efficiencies (88%～94%). Our findings afford a new route to design high‐performance CP bi‐functional metasurfaces operating in other frequency domains or with other functionalities.     

CaIrO3薄膜中的八面体扭转及金属绝缘转变

本文采用激光脉冲沉积(pulsed laser deposition,PLD)方法在NdGaO3(110)(NGO)和(LaAlO_3)_(0.3)(Sr_2AlTaO_6)_(0.7)(001)(LSAT)衬底上生长了厚度变化的钙钛矿结构CaIrO3(CIO)单晶薄膜.在这一体系中,我们观测到了金属绝缘转变现象以及各向异性电输运行为,并且尝试利用应变弛豫调节铱氧八面体绕[100]轴的扭转角度,改变金属绝缘转变温度(TMI).八面体的扭转角度在30nm厚的样品中取得了最大值,同时CIO的TMI取得了最小值.我们推测是八面体的扭转影响了CIO薄膜的带隙宽度,从而造成了TMI的变化以及各向异性电输运行为.     

纳米技术在物理刺激诱导肿瘤治疗中的应用探索

物理刺激诱导的治疗通常是利用多功能诊疗试剂对外界物理刺激,如光、磁场、超声、射频以及X射线等的响应性进行治疗的策略。近年来,这种新颖的癌症治疗方法在临床前期的动物实验组取得了良好的实验结果,因而该策略也备受关注。与传统的化疗疗法不同,物理刺激响应性的试剂本身通常是无毒性的,只有在特定的物理刺激之下才会在病灶部位产生治疗效果。此外,物理刺激诱导的治疗方法还可以与传统治疗策略结合,通过不同的机制达到协同治疗的目的。在这篇综述中,我们将阐述物理刺激诱导治疗的最新发展动态,并深入讨论纳米诊疗试剂在该治疗策略中的重要作用。     

探地雷达反问题的小波-同伦混合反演算法

构造一种求解探地雷达反问题的小波-同伦混合反演算法.利用小波将反问题分解到不同尺度上,在最大尺度上采用同伦反演方法,求得次级尺度的初始近似解,在其余尺度上进行多次迭代修正,以获得全局最小点.算法结合小波反演和同伦反演的优点,数值结果表明其具有较强的全局搜索能力.     

Influence of precipitate-assisted nucleation on the microstructure and mechanical properties of Al-Mg-Si-Cu-Zn alloys

The influence of precipitation on the recrystallization nucleation and mechanical properties of Al-Mg-Si-Cu-Zn alloys was investigated by means of tensile tests, SEM, TEM, XRD and EBSD. The results reveal that there are distinct contributions from the various precipitates that form during annealing and that these critically influence the evolution of microstructure and its associated texture, as well as mechanical behaviour. In contrast to alloy sheets A, B, and C annealed at a lower temperature or for a shorter time, the T4P alloy sheet D with an annealing at 450°C for 3?h not only possesses almost identical strength and elongation, but also a higher average r (0.659) and n (0.313) values, and also a lower Δr (0.091) value. After solution treatment, the four alloy sheets are comprised of equiaxed grains with somewhat different grain sizes and different textures, but texture volume fraction and grain size in alloy sheet D both are decreased due to the effect of precipitate-assisted nucleation during solution treatment. The corresponding nucleation and growth mechanisms of recrystallization grains were established and the relationship between textures and r value in the four alloy sheets was also analyzed on the basis of a Visco-plastic self-consistent (VPSC) model.