Conductive 2D Metal-organic Framework (Co,NiCo, Ni) Nanosheets for Enhanced Non-enzymatic Detection of Urea

2D metal-organic framework (MOF) has potential applications in electrocatalysis owing to fast mass transfer, charge transfer and large specific surface area. Here, we had prepared three conductive 2D MOF based on Ni, NiCo and Co in a simple and rapid way. The 2D nanostructure of MOF was confirmed by SEM and TEM. The chemical composition was studied by XRD, Raman and XPS spectrum. The electrochemical oxidation and detection was investigated through cyclic voltammetry and current-time method. Their sensing performance for urea was determined by varying oxidation potentials and metal sites. The non-enzymatic Ni-, NiCo- and Co-MOF sensors had good catalytic activity for urea. Compared with NiCo- and Co-MOF, Ni-MOF had a wider linear range (0.5–832.5 μM), high sensitivity (1960 μA mM⁻¹ cm⁻²), low detection limit (0.471 μM), and fast response time. The sensors had well repeatability, reproducibility, and selectivity to specific interfering species. Furthermore, Ni- and NiCo-MOF modified electrode was also applied to detection of milk samples. The results showed that the recovery was satisfactory, which further confirmed the effectiveness of non-enzyme sensor. In general, the highly-sensitive 2D Ni- and NiCo-MOF modified electrode has great potential as nonenzymatic urea sensors for real samples detection in hydrogen energy, clinical diagnostics, and environmental protection, et al.     

A 100 kHz Narrow-Pulse-Width Mid-Infrared Optical Parametric Oscillator Based on PPMgLN Crystal

We report a narrow pulse width optical parametric oscillator based on periodically poled MgO:LiNbO₃ (PPMgLN) with a high repetition rate under quasi-phase matched conditions. When the maximum pumping power of the 1,064-nm laser was 14.57 W, the acousto-optical (A-O) Q-switch repetition rate was 100 kHz, and the PPMgLN crystal grating period was 29.5 μm. A 1,474-nm signal light output power of 4.21 W and a 3,828 nm idler light output power of 1.547 W were obtained, corresponding to a pulse width of 9.52 ns and 9.65 ns, respectively. The overall optical–optical conversion efficiency was 39.5%. Additionally, by changing the temperature from 25°C to 150°C, a tunable signal wavelength of 1,474–1,499 nm and idler wavelength at 3,676–3,828 nm of the output laser were achieved.     

V掺杂ZnO透明导电薄膜研究

本文分别采用磁控溅射技术与基于密度泛函理论的平面波赝势方法两种方式, 对高价态差元素V掺杂ZnO薄膜进行研究. 实验研究结果表明: V的掺入并未改变ZnO的生长方式, 所制备的薄膜都呈(002)择优生长; 随着衬底温度增加, VZO薄膜的结晶质量逐步改善, 当衬底温度超过280 ℃时薄膜的结晶质量恶化; 在280 ℃时获得的VZO薄膜电阻率最低3.8×10^-3 Ω·m, 500-2000 nm平均透过率高于85%. 理论模拟结果表明: V以替位形式掺入ZnO六角纤锌矿晶格结构中, 费米能级进入导带, 材料表现出n 型半导体的特性, 导电电子主要由V 3d及O 2p电子轨道提供. 理论计算结果与实验结果的一致性, 表明VZO薄膜具有作为高效Si基薄膜太阳电池透明导电薄膜的应用潜力.     

Experimental demonstration of improved neoclassical transport with quasihelical symmetry

Differences in the electron particle and thermal transport are reported between plasmas produced in a quasihelically symmetric (QHS) magnetic field and a configuration with the symmetry broken. The thermal diffusivity is reduced in the QHS configuration, resulting in higher electron temperatures than in the nonsymmetric configuration for a fixed power input. The density profile in QHS plasmas is centrally peaked, and in the nonsymmetric configuration the core density profile is hollow. The hollow profile is due to neoclassical thermodiffusion, which is reduced in the QHS configuration.     

VxWorks平台内核态ARINC653分区实时调度算法设计与实现

集成模块化航空电子架构(Integrated Modular Avionic, IMA)已成为主流航空电子系统。ARINC 653作为航空电子设备IMA架构的标准应用接口,成为研究航空电子软件编程方法的入口。最新研究表明,VxWorks能够为航空电子分区管理提供最优化的平台。然而,基于VxWorks的ARINC 653高效分区调度算法依然是研究的“盲区”。由此,设计了VxWorks内核态分层ARINC 653分区实时调度算法,提高了分区调度效率,为VxWorks内核ARINC 653完整性的研究提供非常有价值的参考。实验数据说明,相较于传统用户态分区管理模型,该调度算法使分区释放开销和分区释放抖动两项指标均显著降低。     

Dysprosiacarboranes as Organometallic Single-Molecule Magnets

The dicarbollide ion, nido-C₂B₉H₁₁²⁻ is isoelectronic with cyclopentadienyl. Herein, we make dysprosiacarboranes, namely [(C₂B₉H₁₁)₂Ln(THF)₂][Na(THF)₅] (Ln=Dy, 1Dy ) and [(THF)₃(μ-H)₃Li]₂[{η⁵-C₆H₄(CH₂)₂C₂B₉H₉}Dy{η²:η⁵-C₆H₄(CH₂)₂C₂B₉H₉}₂Li] 3Dy and show that dicarbollide ligands impose strong magnetic axiality on the central Dy^III ion. The effective energy barrier (U_eff) for the loss of magnetization can be varied by the substitution pattern on the dicarbollide. This finding is demonstrated by comparing complexes of nido-C₂B₉H₁₁²⁻ and nido-[o-xylylene-C₂B₉H₉]²⁻, which show a U_eff of 430(5) K and 804(7) K, respectively. The blocking temperature defined by the open hysteresis temperature of 3Dy reaches 6.8 K. Moreover, the linear complex [Dy(C₂B₉H₁₁)₂]⁻ is predicted to have comparable properties with the linear [Dy(Cp^Me3)₂]⁺ complex. As such, carboranyl ligands and their derivatives may provide a new type of organometallic ligand for high-performance single-molecule magnets.     

Metal–Organic Framework Membrane Nanopores as Biomimetic Photoresponsive Ion Channels and Photodriven Ion Pumps

Biological ion channels and ion pumps with sub-nanometer sizes modulate ion transport in response to external stimuli. Realizing such functions with sub-nanometer solid-state nanopores has been an important topic with wide practical applications. Herein, we demonstrate a biomimetic photoresponsive ion channel and photodriven ion pump using a porphyrin-based metal–organic framework membrane with pore sizes comparable to hydrated ions. We show that the molecular-size pores enable precise and robust optoelectronic ion transport modulation in a broad range of concentrations, unparalleled with conventional solid-state nanopores. Upon decoration with platinum nanoparticles to form a Schottky barrier photodiode, photovoltage across the membrane is generated with “uphill” ion transport from low concentration to high concentration. These results may spark applications in energy conversion, ion sieving, and artificial photosynthesis.     

Ultrastable Surface-Dominated Pseudocapacitive Potassium Storage Enabled by Edge-Enriched N-Doped Porous Carbon Nanosheets

The development of ultrastable carbon materials for potassium storage poses key limitations caused by the huge volume variation and sluggish kinetics. Nitrogen-enriched porous carbons have recently emerged as promising candidates for this application; however, rational control over nitrogen doping is needed to further suppress the long-term capacity fading. Here we propose a strategy based on pyrolysis–etching of a pyridine-coordinated polymer for deliberate manipulation of edge-nitrogen doping and specific spatial distribution in amorphous high-surface-area carbons; the obtained material shows an edge-nitrogen content of up to 9.34 at %, richer N distribution inside the material, and high surface area of 616 m² g⁻¹ under a cost-effective low-temperature carbonization. The optimized carbon delivers unprecedented K-storage stability over 6000 cycles with negligible capacity decay (252 mA h g⁻¹ after 4 months at 1 A g⁻¹), rarely reported for potassium storage.     

Cross-Module Enoylreduction in the Azalomycin F Polyketide Synthase

The colinearity of canonical modular polyketide synthases, which creates a direct link between multienzyme structure and the chemical structure of the biosynthetic end-product, has become a cornerstone of knowledge-based genome mining. Herein, we report genetic and enzymatic evidence for the remarkable role of an enoylreductase in the polyketide synthase for azalomycin F biosynthesis. This internal enoylreductase domain, previously identified as acting only in the second of two chain extension cycles on an initial iterative module, is shown to also catalyze enoylreduction in trans within the next module. The mechanism for this rare deviation from colinearity appears to involve direct cross-modular interaction of the reductase with the longer acyl chain, rather than back transfer of the substrate into the iterative module, suggesting an additional and surprising plasticity in natural PKS assembly-line catalysis.