一步CVD法制备WS2-MoS2垂直异质结及其表征

本文主要研究了WS₂-MoS₂垂直异质结的制备及其光电性能。以氧化钼(MoO₃)、氧化钨(WO₃)、硫粉(S)作为反应物,采用改良的一步化学气相沉积法(CVD)实现高质量的WS₂-MoS₂垂直异质结的制备。使用拉曼光谱仪(Raman)、光致发光光谱仪(PL)、光学显微镜(OM)、原子力显微镜(AFM)、透射电子显微镜(TEM)、X射线光电子能谱仪(XPS)等设备,对异质结的形貌、元素组成等进行了表征。最后制备了基于WS₂-MoS₂异质结的光电探测器,测量了包括输出特性曲线、转移特性曲线、光电流曲线等光电特性。经测试,WS₂-MoS₂异质结光电探测器在532 nm激光模式下展现了良好的光响应特性,使其能应用于高效率的光电子器件的制备,在微电子学领域具有广阔的应用前景。     

Synthesis,Characterization and Thermal Properties of Bio-Based Poly(Ethylene 2,5-Furan Dicarboxylate)

Poly(ethylene 2,5-furan dicarboxylate) (PEF), based on renewable resources, was synthesized using several different polycondensation methods and then characterized. In this study the properties of polycondensed PEF were compared using five types of catalysts and two types of monomers. For the optimal catalyst, the influence of the amount of catalyst, polycondensation temperature and polycondensation time were investigated and, thereafter, direct and indirect polycondensations were compared at the optimum conditions. Various properties of PEF were characterized by Fourier transform infrared spectroscopy, intrinsic viscosity, gel permeation chromatography, ¹H NMR, differential scanning calorimetry, dynamic mechanical thermal analysis, thermogravimetric analysis, and X-ray diffraction for comparison with the properties of polyethylene terephthalate PET. In addition, the rheological behaviour and mechanical properties of the PEFs were tested. The results confirmed that the obtained properties of PEF were similar to the corresponding properties of PET.     

A dual functional 1D Cd-based coordination polymer for the highly luminescent sensitive detection of Fe3+ and picric acid

Fluorescent coordination polymers have drawn extensive attention in sensing applications. Herein, we report a carbazole-based one-dimensional coordination polymer [CdL(H₂O)(DMF)₂]·DMF ( CdL , H₂L = 9H-carbazole-2,7-dicarboxylic acid, DMF = N,N-dimethylformamide). In CdL , each Cd²⁺ ion is four-bridged by carboxylates, which is further linked by the carbazole units to form a one-dimensional Cd–O–C chains along the c-axis. CdL displays high water stability in the pH range of 3–10. Luminescence experiments indicate that CdL could selectively detect Fe³⁺ during the concentration range of 0–0.1 mm in water with a K_sv of 8022 m ⁻¹ and picric acid (PA) within the concentration range of 0–0.05 mm in methanol solution with a K_sv of 17948 m ⁻¹ respectively. The above results reveal that CdL can be applied as a multiresponse luminescence sensor for selectively sensing for Fe³⁺ in water and PA in methanol solution.     

Syntheses,structures, and properties of four coordination polymers based on 2,7-di(pyridin-4-yl)-9H-fluoren-9-one

Four coordination polymers (CPs), [Cd(2,7-dpfo)₂(NO₃)₂(CH₃OH)]_n (1) , [Zn(2,7-dpfo)(NO₃)(CH₃COO)]_n (2) , [Co(2,7-dpfo)₂(H₂L)]_n (3) , and [Ni(2,7-dpfo)₂(H₂L)]_n (4) (where 2,7-dpfo is 2,7-di(pyridin-4-yl)-9H-fluoren-9-one and H₄L is 1,1′:4′,1′′-terphenyl-4,2′,5′,4′′-tetracarboxylic acid), were synthesized and structurally characterized. Compounds 1 – 4 were determined by elemental analyses, single crystal X-ray diffraction analyses, powder X-ray diffraction, infrared spectroscopy, and thermogravimetric analyses. Compound 1 displays a one-dimensional (1D) zigzag chain structure, while compound 2 possesses a 1D ladder chain structure. Compounds 3 and 4 are isostructural and consist of 1D chains. The solid-state luminescent properties of 1 and 2 and the magnetic properties of 3 and 4 were also investigated.     

低熔点微晶封接玻璃的应用研究

探讨低熔点微晶封接玻璃的技术要求和封接件的匹配封接条件，并给出部分低熔点微晶封接玻璃的性质和典型封接工艺。     

High‐speed separation and detection of amino acids in laver using a short capillary electrophoresis system

A high‐speed separation method of capillary MEKC with LIF detection had been developed for separation and determination of amino acids in laver. The CE system comprised a manual slotted‐vial array (SVA) for sample introduction that could improve the separation efficiency by reducing injection volume. Using a capillary with 80 mm effective separation length, the separation conditions for amino acids were optimized. Applied with the separation electric field strength of 300 V/cm, the ten amino acids could be completely separated within 2.5 min with 10 mol/L Na₂HPO₄–NaOH buffer (pH = 11.5) including 30 mmol/L SDS. Theoretical plates for amino acids ranged from 72 000 to 40 000 (corresponding to 1.1–2.0 μm plate heights) and the detection limits were between 25 and 80 nmol/L. Finally, this method was applied to analyze the composition of amino acids in laver and eight known amino acids could be found in the sample. The contents of five amino acids, tyrosine, glutamic acid, glycine, lysine, and aspartic acid that could be completely separated in real sample were determined. The recoveries ranged from 82.3% to 123% that indicated the good reliability for this method in laver sample analysis.     

多组份烧结型气体传感器

本文报导了以SnO2、ZnO和γ—F?2O3三种半导体金属氧化物按一定比例混合后作为基体材料制成的气敏元件,实验表明,这种元件对C4H10敏感     

固体渗硼的铬不锈钢组织和性能

为增进不锈钢性能,进行了不锈钢固体渗硼试验。结果表明;渗层表面形成了FeB、Fe_zB相。并随工艺变化可调整其相对含量。此渗层可以极大地提高耐磨性。但耐蚀性能降低。     

超导相Tl2Ca3Ba2Cu4O12的制备与结构研究

我们已制备出Tl_2 Ca Ba_2 Cu_2O_8(2122)和Tl_2Ca_2 Ba_2 Cu_3 O_(10)(2223)两个纯相,并对它们的晶体结构和性质进行了研究。现在我们又制备出一种新的超导相,它的组成为Tl_2 Ca_3 Ba_2 Cu_4 O_(120(2324),并进一步研究了它的超导性质和晶体结构。     

An Entropy Metric for Regular Grammar Classification and Learning with Recurrent Neural Networks

Recently, there has been a resurgence of formal language theory in deep learning research. However, most research focused on the more practical problems of attempting to represent symbolic knowledge by machine learning. In contrast, there has been limited research on exploring the fundamental connection between them. To obtain a better understanding of the internal structures of regular grammars and their corresponding complexity, we focus on categorizing regular grammars by using both theoretical analysis and empirical evidence. Specifically, motivated by the concentric ring representation, we relaxed the original order information and introduced an entropy metric for describing the complexity of different regular grammars. Based on the entropy metric, we categorized regular grammars into three disjoint subclasses: the polynomial, exponential and proportional classes. In addition, several classification theorems are provided for different representations of regular grammars. Our analysis was validated by examining the process of learning grammars with multiple recurrent neural networks. Our results show that as expected more complex grammars are generally more difficult to learn.