Wenshuo Wang

Optical identification of MoS 2 /graphene heterostructure on SiO 2 /Si substrate

Chemical vapor deposition (CVD) method is considered to be an efficient way to prepare Van der Waals heterostructure. However, accurately and hurtlessly identifying the layers number of MoS(2) in the heterostructure is still a challenge. Here, we calculated the expected contrast between MoS(2)/graphene heterostructure and underlying SiO(2)/Si substrate by using a Fresnel law based model. And we indicated that contrast at blue and green incident light is ideal for visibility and layer number detecting. Our measured value showed good agreement with calculated ones. And Raman spectrum helped to confirm our speculation.

The fabrication of nanochain structure of gold nanoparticles and its application in ractopamine sensing

The illegal food additives including ractopamine and melamine throw a serious threat to human health. In this paper, the ractopamine and melamine were first used to form the nanochain structure of citrate-stabilized gold nanoparticles (AuNPs) with a convenient and inexpensive method. The fabricated nanochain structure consisting of several AuNPs was characterized by Scanning Electron Microscopy. A new longitudinal surface plasma resonance, which could be adjusted from visible to near infrared range, was observed in absorption spectra due to the aggregation of AuNPs. This could be well explained by Finite Different Time Domain algorithm theoretically. As confirmed by Fourier Transform Infrared Spectroscopy, the complex formed by hydrogen-bonding interaction between melamine and ractopamine could effectively promote the aggregation of AuNPs that was useful to develop the sensitivity and selectivity for the detection of ractopamine. Hence, the plasmonic coupling phenomenon of gold nanochain could be applied in bio-assay for ractopamine through the change of solutions color and optical absorption band with naked eye or absorption spectra. The linear range was broadened to (1.23 × 10(-7)M, 1.11 × 10(-6)M) and the limit of detection was extended to 4.10 × 10(-8)M (S/N=3). More importantly, this time-saving method will be promising in rapid and selective detection of β-agonist for clinical applications.

Ultraviolet Photodetectors With Narrow-Band Spectral Response Using TAPC Donor

Organic ultraviolet photodetectors (PDs) with a narrow-band spectral response are fabricated. TAPC and PBD were utilized as the electron donor and acceptor, respectively. Glass/indium tin oxide (ITO) was employed as the anode contact and the incident light window. The PDs reveal a narrow response width of 30 nm at 316-346 nm. A peak response of 0.12 A/W at 330 nm and a photo-to-dark ratio of about 1.1 ×102 under 330-nm light illumination with an intensity of 0.95 mW/cm2 were achieved. The realization of the narrow-band response should be ascribed to the steep absorption of organic materials at the long wavelength and the blocking role of glass/ITO contact at the short wavelength.

Customized transportation service design for railway express delivery

The concept of mass customization has received considerable attention in the research literature in recent years. However, the existing research is limited in understanding of mass customization strategies and largely focuses on manufacturing operations. This paper focuses on the customized transportation service design problem for railway express delivery to satisfy increasing individual demand in transportation time limit. To address this problem, this paper develops a linear programming model and proposes a two-stage approach for solving this problem. Through computational testing, we explore the efficiency of this solution approach.

Grey system theory based default risk model of power clients

To be clear of the default probability of electricity fees from power clients in advance and change the postmortem management mode to the preventive management mode, it would decrease the default risk greatly in the process of electricity sales in the utility. Based on the analysis of complicated reasons of default, the main elements whose effect on default are known, the risk model involved with feature variables of default is constructed with the theory of grey system predication. Next, using a grey cluster algorithm, we classified clients into different categories according to the prediction of theirs feature variables, which would be valuable reference for power company to subdivide the consumption market and make out distinguishing credit management strategy.

Grey incidence theory based credit discriminent in the electricity market of contract transaction

After restructured the electricity industry, trading among those utilities like generation plants, grid companies, retail agents becomes more and more frequently and complicatedly, and risk existed unavoidably. Credit Evaluation on the opponent is an effective measure to decreasing the potential losses. Firstly, different transaction mode in electricity market was analyzed, with the theory of credit, the credit management indices used in long-term contract transaction was constructed, which is of simpleness and practicality and is suitable for applying it into the primary electricity market. When credit evaluation is carried out, more or less, the information is uncertain; therefore, the grey incidence approach was employed. With the sample data given, which would imply their correlatively among those indices, we could use cluster grey incidence degree to determine the weight of every index automatically, and we also could compare the grey incidence degree of unknown object to that of the typical samples, then we would realize the credit rating that those unknown objects would be attributed to in advance, finally, a case verify the validity of the approach we presented.