A Fully Conjugated Covalent Organic Framework with Oxidative and Reductive Sites for Photocatalytic Carbon Dioxide Reduction with Water

Constructing a powerful photocatalytic system that can achieve the carbon dioxide (CO₂) reduction half-reaction and the water (H₂O) oxidation half-reaction simultaneously is a very challenging but meaningful task. Herein, a porous material with a crystalline topological network, named viCOF-bpy-Re, was rationally synthesized by incorporating rhenium complexes as reductive sites and triazine ring structures as oxidative sites via robust −C=C− bond linkages. The charge-separation ability of viCOF-bpy-Re is promoted by low polarized π-bridges between rhenium complexes and triazine ring units, and the efficient charge-separation enables the photogenerated electron–hole pairs, followed by an intramolecular charge-transfer process, to form photogenerated electrons involved in CO₂ reduction and photogenerated holes that participate in H₂O oxidation simultaneously. The viCOF-bpy-Re shows the highest catalytic photocatalytic carbon monoxide (CO) production rate (190.6 μmol g⁻¹ h⁻¹ with about 100 % selectivity) and oxygen (O₂) evolution (90.2 μmol g⁻¹ h⁻¹) among all the porous catalysts in CO₂ reduction with H₂O as sacrificial agents. Therefore, a powerful photocatalytic system was successfully achieved, and this catalytic system exhibited excellent stability in the catalysis process for 50 hours. The structure–function relationship was confirmed by femtosecond transient absorption spectroscopy and density functional theory calculations.     

Azopyridine-imidacloprid derivatives as photoresponsive neonicotinoids

A series of imidacloprid derivatives containing an azopyridine motif as a photoswitchable functional group were designed and synthesized. The new version of photoresponsive imidacloprid analogues showed improved solubility in comparison with their azobenzene analogues. 1.2 to 2-fold activity difference was observed for these azopyridine-imidacloprids against house fly (Musca domestica) and cowpea aphid (Aphis craccivora) upon irradiation.     

以四磺基铝酞菁-牛血清白蛋白为底物的荧光恢复均相法测定胃蛋白酶

酸性介质中,红区荧光探针四磺基铝酞菁(AlS4Pc)的荧光被白蛋白显著猝灭,加入胃蛋白酶后,体系荧光明显回复。基于此现象,建立了荧光恢复均相测定胃蛋白酶的新方法。考察了各种影响因素,在最佳实验条件(pH2.5、反应温度50℃、反应时间1h)下,本方法的线性范围为0.04～4mg/L,检出限为20μg/L。用本方法测定实际样品中胃蛋白酶,取得了满意的结果。     

Itinerant to relocalized transition of f electrons in the Kondo insulator CeRu4Sn6

The three-dimensional electronic structure and the nature of Ce 4f electrons of the Kondo insulator CeRu₄Sn₆ are investigated by angle-resolved photoemission spectroscopy, utilizing tunable photon energies. Our results reveal (i) the three-dimensional k-space nature of the Fermi surface, (ii) the localized-to-itinerant transition of f electrons occurs at a much high temperature than the hybridization gap opening temperature, and (iii) the “relocalization” of itinerant f-electrons below 25 K, which could be the precursor to the establishment of magnetic order.     

ZnO/CdS复合材料的合成与可见光催化性能

采用喷雾辅助气相沉积法在水热法合成的ZnO纳米线上沉积CdS纳米颗粒。采用X射线衍射仪（XRD）、激光拉曼仪（Raman）、扫描电镜（SEM）、透射电镜（TEM）、X射线光电子能谱分析谱（XPS）和紫外可见漫反射光谱等测试手段对复合光催化剂进行表征。结果表明,3~10 nm的CdS纳米粒子修饰在直径约为100 nm ZnO纳米线的表面。XPS和Raman表明复合材料中ZnO和CdS之间存在化学相互作用。可见光催化降解罗丹明B实验结果表明ZnO/CdS复合材料的催化性能优于单相CdS或ZnO,沉积时间为30 s合成的ZnO/CdS速率常数分别是CdS和ZnO的2.91和4.03倍,且具有较高的稳定性。ZnO/CdS复合材料光催化性能增强的可能原因为光吸收范围的拓展和光生载流子分离效率的提高。     

单级大功率斯特林型脉管制冷机模拟与实验研究

为了研究大功率斯特林型脉管制冷机中存在的流动的不均匀性、回热器和脉管内的温度不均匀性、制冷机与压缩机的阻抗匹配等问题,本文基于模拟软件Sage设计制造了一台单级大功率斯特林型脉管制冷机并对其进行了初步试验研究。在60 Hz工作频率,充气压力为1.9 MPa时,800 W输入功率下达到最低无负荷制冷温度56.9 K;充气压力为2.0MPa,输入功率为4 kW时制冷量为41.2 W@77 K,与理论模拟结果存在较大差距。实验发现回热器存在严重的温度不均匀性,中部最大温差高达120 K。     

分形多孔介质的粒子扩散特点(Ⅱ)

本文进一步讨论了粒子在分形结构中的扩散,首先计算测定了各分形结构的谱维数,然后对其布朗运动特点进 行了分析讨论,最后模拟得到了粒子扩散概率分布,它们表现出很多有趣的特征:不均匀性,内含空洞和标度性等.这些 结果可以更好地了解气体在分形结构中的扩散。     

指向Lyapunov指数及其在单输入单输出系统故障检测中的应用

针对单输入单输出系统的故障检测, 采用混沌振荡器作为激励源, 并利用非一致延迟时间法对被测系统输出时间序列进行相空间重构. 在相空间中平衡点附近定义了指向Lyapunov指数, 并用其对被测系统输出在相空间中平衡点附近特征结构进行分析, 实现了对单输入单输出系统的故障检测. 仿真结果表明, 被测系统的参数变化将会引起相空间中平衡点附近特征结构的改变, 指向Lyapunov指数对其变化敏感. 关键词： 混沌激励 指向Lyapunov指数 故障检测 单输入单输出系统     

Globally Convergent Broyden-Like Methods for Semismooth Equations and Applications to VIP, NCP and MCP

In this paper, we propose a general smoothing Broyden-like quasi-Newton method for solving a class of nonsmooth equations. Under appropriate conditions, the proposed method converges to a solution of the equation globally and superlinearly. In particular, the proposed method provides the possibility of developing a quasi-Newton method that enjoys superlinear convergence even if strict complementarity fails to hold. We pay particular attention to semismooth equations arising from nonlinear complementarity problems, mixed complementarity problems and variational inequality problems. We show that under certain conditions, the related methods based on the perturbed Fischer–Burmeister function, Chen–Harker–Kanzow–Smale smoothing function and the Gabriel–Moré class of smoothing functions converge globally and superlinearly.     

Brilliant cresyl blue as a new red region fluorescent probe for determination of nucleic acids

A fluorescence quenching method was developed for determination of microamounts of nucleic acids by using brilliant cresyl blue (BCB) as a new red region fluorescent probe. In aqueous hexylmethylene tetramine solution, BCB showed maximum excitation and emission wavelengths at 626 and 670 nm, respectively, and the fluorescence of BCB could be greatly quenched by DNA (or RNA). Under optimal conditions, the calibration graphs are linear over the range of 0.02–0.80 μg/ml for SM DNA and 0.25–1.5 μg/ml for yeast RNA. The corresponding detection limits are 7 ng/ml for SM DNA and 25 ng/ml for yeast RNA, respectively. SM DNA can be determinated in the presence of 40% (w/w) RNA, and the relative standard deviation of six measurements is 2.5% for 500 ng/ml SM DNA. The result of the determination of golden staphylococcus DNA by this method was satisfactory.