Atomic and Electronic Reconstruction in Defective 0D Molybdenum Carbide Heterostructure for Regulating Lower-Frequency Microwaves

0D nanomaterials with high efficiency of atom utilization possess extraordinary tunability over bulk materials. Precise reconstruction of atoms in a 0D nanoparticle toward tuning of crystalline phases and defects is highly desirable but remains a grand challenge. In this study, a crystallization rate-controlled strategy is reported to achieve controllable reconstruction of atoms in situ, which inducts a series of monodisperse 0D molybdenum carbide nanoparticles (Mo_xC NP) that anchor on a carbon matrix with adjustable crystalline phases and atom vacancies. Aberration-corrected transmission electron microscopy, electron paramagnetic resonance technique, density functional theory calculation, and electron holography jointly reveal the atomic reconstruction process and confirm its remarkable effects of optimizing the local electronic states and enhancing the heterointerface interactions. As a result, the optimized MoC/Mo₂C heterostructure on the carbon matrix is shown to enable the promoted dielectric response and generate more than 90% absorption of lower-frequency microwaves (the current 5^th-generation communication band). The control of atomic reconstruction may provide an effective pathway for unlocking tunable dielectric properties of 0D nanomaterials toward various technological applications.     

Thermal-Triggered “On–Off” Switchable Triboelectric Nanogenerator Based on Two-Way Shape Memory Polymer

Developing multifunctional triboelectric nanogenerators (TENGs) with special intelligence is of great significance for next-generation self-powered electronic devices. However, the relevant work on the intelligent TENGs, especially those spontaneously responsive to external stimuli, is rarely reported. Herein, an intelligent TENG with thermal-triggered switchable functionality and high triboelectric outputs is developed by designing a movable triboelectric layer, which is driven by a two-way shape memory polyurethane. The resultant TENG device can be spontaneously switched on/off in response to the environmental temperature change, i.e., switching on at 0 °C and off at 60 °C. At the “on” state, the developed TENG exhibits excellent triboelectric performance with a maximum output power density of 5.15 W m⁻² at a pressure of 30 kPa due to the unique advantages of micro-/nanofiber triboelectric surfaces. Furthermore, the great potential of the switchable TENG in intelligent wearable electronic applications is demonstrated, which can serve as not only the sensing element for monitoring human movement and physical condition in a cold environment but also the thermal-driven switch for turning on/off the heating function on demand. The intelligent “on–off” switchable TENG combined with excellent triboelectric performance may provide new opportunities for future self-powered wearable electronics.     

Bioinspired Artificial Visual System Based on 2D WSe2 Synapse Array (Adv. Funct. Mater. 41/2023)

Machine vision systems that capture images for visual inspection and recognition tasks must be able to perceive, memorize, and compute any color scene. To achieve this, most of the current visual systems use circuits and algorithms which may reduce efficiency and increase complexity. Herein, a 2D semiconductor tungsten diselenide (WSe₂)-based phototransistor that successfully demonstrates an artificial vision system integrating the processing capability of visual information sensing memory, is reported. Furthermore, based on a 6 × 6 fabricated retinal perception array, artificial visual information sensing memory and processing system are proposed to perform image recognition tasks, which can avoid the time delay and energy consumption caused by data conversion and movement. On the other hand, highly linear symmetric synaptic plasticity can be achieved based on the modulation of carrier types in WSe₂ transistors with different thicknesses, facilitating the high level of training and inference accuracy for artificial neural networks. Last, through training and inference simulations, the feasibility of the hybrid synapses for optical neural networks (ONN) is demonstrated.     

On-line galvanic cell generated electrochemiluminescence determination of acyclovir based on the flow injection sampling

A new simple, rapid and cost effective flow injection (FI) electrochemiluminescence (ECL) method was described for the determination of acyclovir (9,2-hydroxyethoxy) methyl guanine. In the presence of acyclovir, the luminol electrochemiluminescence generated by a mini on-line galvanic cell could be greatly sensitized in alkaline medium. The relative electrochemiluminescence intensity was found to increase linearly with increasing concentration of acyclovir, which was corroborated by the calculated correlation coefficient value of 0.9994 (n=7). The limit of detection was 1.6×10⁻⁷ mol l⁻¹ and the limit of quantification was 7.9×10⁻⁷ mol l⁻¹. The proposed method was applied to the determination of acyclovir in pharmaceutical formulations. The reliability of the assay method was established by parallel determination and by standard-addition method. Experiment results demonstrated the described mini analysis system, while being simple and less time consuming, was accurate, precise and reproducible (R.S.D. = 1.6%, recoveries = 99 - 103%). Further experiments indicated that there was no significant difference between the results obtained by the proposed and official methods.     

Regiocontrolled dimerization of asymmetric diazaheptacene derivatives toward X-shaped porous semiconductors

Conformationally rigid X-shaped PAHs are attracting interest due to their self-assembly into unique networks and as models to study through-space exciton and charge delocalization in one single molecule. We report here the synthesis of X-shaped PAHs by dimerization of diazaheptacene diimides. The diimide groups are employed to effectively direct the self-assembly into antiparallel dimer aggregates, which assist the compounds to undergo a regiocontrolled [4 + 4] dimerization, leading to an X-shaped conformation bearing electron-poor and -rich subunits. The resulting PAHs are found to pack in 2D layers with large open channels and infinite π⋯π arrays. Furthermore, these highly crystalline porous materials serve as electron-transporting materials in OFETs due to the long-range π-stacked arrays in the layers. This work presents a potentially generalizable strategy, which may provide a unique class of porous semiconductors for organic devices, taking advantage of their open channels.

The synthesis of conformationally rigid X-shaped PAHs by regiocontrolled cyclodimerization of diazaheptacene diimides is presented. The resulting porous materials exhibit enhanced semiconducting behaviors with large open channels.     

Simultaneous determination of rifampicin and isoniazid by continuous-flow chemiluminescence with artificial neural network calibration

In this paper a continuous-flow chemiluminescence (CL) system with artificial neural network calibration is proposed for simultaneous determination of rifampicin and isoniazid. This method is based on the different kinetic spectra of the analytes in their CL reaction with alkaline N-bromosuccinimide as oxidant. The CL intensity was measured and recorded every second from 1 to 300 s. The data obtained were processed chemometrically by use of an artificial neural network. The experimental calibration set was 20 sample solutions. The relative standard errors of prediction for both analytes were approximately 5%. The proposed method was successfully applied to the simultaneous determination of rifampicin and isoniazid in a combined pharmaceutical formulation.     

Palladium-catalyzed hydroalkylation of methylenecyclopropanes with simple hydrazones

A palladium-catalyzed hydroalkylation reaction of methylenecyclopropanes via highly selective C–C σ-bond scission was achieved under mild conditions, in which simple hydrazones served as carbanion equivalents. This method featured good functional group compatibility, affording high yields of C-alkylated terminal alkenes.

A palladium-catalyzed hydroalkylation of methylenecyclopropanes via selective C–C σ-bond scission was achieved, in which simple hydrazones served as carbanion equivalents. This method affords high yields of C-alkylated terminal alkenes with good functional group compatibility.     

“Pinwheel-like” phthalocyanines with four non-peripheral chiral menthol units: Synthesis,spectroscopy, and electrochemistry

Chiral side chains have been incorporated onto the non-periphery moiety of phthalocyanine ring, resulting in a pair of chiral phthalocyanines, (D)-and (L)-1,8,15, 22-tetrakis(2-isopropyl-5-methylcyclohexoxyl)phthalocyanine.     

Thrombolytic Agents: Nanocarriers in Targeted Release

A thrombus, known as a blood clot, may form within the vascular system of the body and impede blood flow. Thrombosis is the most common underlying pathology of cardiovascular diseases, contributing to high morbidity and mortality. However, the main thrombolytic drugs (urokinase, streptokinase, etc.) have shortcomings, including a short half-life, serious side effects and a lack of targeting, that limit their clinical application. The use of nano-drug delivery systems is expected to address these problems and a variety of approaches, including biological and physical responsive systems, have been explored. In this report, recent advances in the development of targeted nano-drug delivery systems are thoroughly reviewed.     

三苯胺类小分子的合成及其AIE性能研究

以二苯胺、碘苯、对碘甲苯以及对碘苯甲醚为原料,合成了三苯胺及其衍生物T1~T5(4-甲氧基三苯胺、4-甲基三苯胺、4-醛基三苯胺、4-乙烯基三苯胺),并对其紫外-可见吸收光谱与荧光光谱进行了检测。结果表明,连有甲氧基、甲基、乙烯基取代基的三苯胺化合物在甲醇/氯仿混合溶液中具有聚集诱导发光(AIE)性能;而醛基取代的4-醛基三苯胺表现出了聚集荧光猝灭(ACQ)现象。