Mechanical properties of graphene films enhanced by homo-telechelic functionalized polymer fillers via π–π stacking interactions

Most researches on graphene/polymer composites are focusing on improving the mechanical and electrical properties of polymers at low graphene content instead of paying attention to constructing graphene’s macroscopic structures. In current study the homo-telechelic functionalized polyethylene glycols (FPEGs) were tailored with π-orbital-rich groups (namely phenyl, pyrene and di-pyrene) via esterification reactions, which enhanced the interaction between polyethylene glycol (PEG) molecules and chemical reduced graphene oxide (RGO) sheets. The π–π stacking interactions between graphene sheets and π-orbital-rich groups endowed the composite films with enhanced tensile strength and tunable electrical conductivity. The formation of graphene network structure mediated by the FPEGs fillers via π–π stacking non-covalent interactions should account for the experimental results. The experimental investigations were also complemented with theoretical calculation using a density functional theory. Atomic force microscope (AFM), scanning electron microscope (SEM), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), thermal gravimetric analysis (TGA), UV–vis and fluorescence spectroscopy were used to monitor the step-wise preparation of graphene composite films.     

Analysis of a Novel Flux-Weakening Structure of High-Speed Permanent-Magnet Motors Based on Soft-Magnetic Ferrite

Soft-magnetic ferrite has advantages of high initial magnetic permeability, high electric resistivity, low loss and low cost in the high-frequency alternating field. Considering the characters of soft-magnetic ferrite, this paper uses a soft-magnetic ferrite ring as stator core and presents a novel field-weakening structure of high speed PM motors. Based on this structure, a novel field-weakening method of PM motors can be presented. The equivalent reluctance of permanent magnetic field circuit can be changed by altering saturation degree of soft-magnetic ferrite core in this method. For the convenience of analysis and calculation, considering the magnetic field distribution in the motors, this paper deduces an equivalent two-dimensional finite element model of three-dimensional magnetic field, by which the field-weakening parameters of high speed PM motor can be conveniently analyzed. The simulation results of finite element model prove: the field-weakening structure of high speed PM motor based on soft-magnetic ferrite, presented in this paper, is valid and feasible, offers a valid and applicative method for field-weakening control of high speed PM motor.     

EAST电源数据采集控制系统的设计与实现

随着EAST装置不断升级,现有的电源数据采集及其控制系统已不能满足等离子体长时间放电要求,需设计新型EAST电源数据采集控制系统.该控制系统采用LAMP架构,对采集参数管理加入多种安全验证,实现了数据采集系统的远程启动、实时监测、异常检测、故障恢复和日志管理,解决了原有系统移植性差和安全性弱等问题;此外通过对实验数据进行有效性分析,并对有效实验数据的关键参数进行统计,实现了基于数据内容的检索.实验结果表明,该系统能够稳定运行,可有效降低人为故障,缩短异常处理时间,具备良好的扩展性和移植性,对EAST其他子装置的数据采集及其控制系统的升级有很好的参考价值.     

Binarization and cleanup of handwritten text from carbon copy medical form images

This paper presents a methodology for separating handwritten foreground pixels, from background pixels, in carbon copied medical forms. Comparisons between prior and proposed techniques are illustrated. This study involves the analysis of the New York State (NYS) Department of Health (DoH) Pre-Hospital Care Report (PCR) [Western Regional Emergency Medical Services, Bureau of Emergency Medical Services, New York State (NYS) Department of Health (DoH), Prehospital Care Report v4.] which is a standard form used in New York by all Basic and Advanced Life Support pre-hospital health care professionals to document patient status in the emergency environment. The forms suffer from extreme carbon mesh noise, varying handwriting pressure sensitivity issues, and smudging which are further complicated by the writing environment. Extraction of handwriting from these medical forms is a vital step in automating emergency medical health surveillance systems.     

High-temperature ferromagnetism of Ni-doped PbPdO2 nanograin films synthesized by sol-gel spin-coating method

The single-phase Ni-doped PbPdO₂ films with a body-centered orthorhombic structure were synthesized by the sol-gel spin-coating method and an oxidation treatment. The films with a thickness of about 440 nm were found to have a nanograin structure and large amount of Pb vacancies. The valence states of Ni and Pd ions within the Ni-doped PbPdO₂ films were very close to 2+, while the Pb ions exhibited a mixed valence between 2+ and 4+. The existence of Pb vacancies and the low electronegativity of Pb²⁺ ion resulted in the increase of the valence of Pb ions. The analysis of the magnetic properties indicated that the magnetisms of the single-phase Ni-doped PbPdO₂ nanograin films were all composed of the ferromagnetism and the paramagnetism. The ferromagnetism enhanced with the calcination temperature increasing and could be retained up to 380 K. A carrier-mediated mechanism bridged to the bound magnetic polaron model based on the Pb vacancies, the doped Ni ions and the Pb ions with a valence higher than 2+ were used to explain the magnetic origin of these Ni-doped PbPdO₂ nanograin films.     

Application of HDF5 in long-pulse quasi-steady state data acquisition at high sampling rate

A new high sampling rate quasi-steady state data-acquisition system has been designed for the microwave reflectometry diagnostic of EAST experiments. In order to meet the requirements of long-pulse discharge and high sampling rate, it is designed based on PXI Express technology. A high-performance digitizer National Instruments PXIe-5122 with two synchronous analog input channels in which the maximum sampling rate is 100 MHz has been adopted. Two PXIe-5122 boards at 60 MSPS and one PXIe-6368 board at 2 MSPS are used in the system and the total throughput is about 500 MB/s. To guarantee the large amounts of data being saved continuously in the long-pulse discharge, an external hard-disk data stream enclosure NI HDD-8265 in which the capacity of sustained speed of reading and writing is 700 MB/s. And in RAID-5 mode its storage capacity is 80% of the total.The obtained raw data firstly stream continuously into NI HDD-8265 during the discharge. Then it will be transferred to the data server automatically and converted into HDF5 file format. HDF5 is an open source file format for data storage and management which has been widely used in various fields, and suitable for long term case. The details of the system are described in the paper.     

Discrimination of Kernel Quality Characteristics for Sunflower Seeds Based on Multispectral Imaging Approach

Multispectral imaging in the visible and near-infrared (405–970 nm) regions was tested for nondestructive discrimination of insect-infested, moldy, heterochromatic, and rancidity in sunflower seeds. An excellent classification (accuracy >97 %) for intact sunflower seeds could be achieved using Fisher’s linear discriminant function based on 10 feature wavelengths that were selected from the original 19 wavelengths by Wilks’ lambda stepwise method. Intact sunflower seeds with different degree of rancidity could be precisely clustered by multispectral imaging technology combined with principal component analysis-cluster analysis (PCA-CA). Our results demonstrate the capability of multispectral imaging technology as a tool for rapid and nondestructive analysis of seed quality attributes, which enables many applications in the agriculture and food industry.     

Defect-free MoS2 nanosheets: Advanced nanofillers for polymer nanocomposites

The preparation of defect-free MoS₂ nanosheets is a key challenge and essential for practical applications. Herein the dodecanethiol was firstly performed as the antioxidant and surface modifier to produce the defect-free MoS₂ by direct ultrasonication of bulk MoS₂ in N,N-dimethylformamide. Incorporating defect-free MoS₂ into polyethylene obviously improved the properties of PE/MoS₂ nanocomposites. For crystallization under quiescent condition, the half crystallization time (t₀.₅) of nanocomposites containing 0.2 wt% MoS₂ was reduced by 87.0% compared to that of neat PE. A 54.3 °C increase in the temperature of maximum weight loss (T_max) was observed by inclusion of as low as 0.7 wt% defect-free MoS₂ nanosheets. In addition, the uniformly distributed MoS₂ can considerably improve the mechanical properties of composites. These observations suggest that the robust nature, dramatic barrier action of defect-free MoS₂ and the strong nanosheets/matrix interfacial adhesion would be the motivation to improve the performance of the polymeric nanocomposites.     

An immunomagnetic-bead-based enzyme-linked immunosorbent assay for sensitive quantification of fumonisin B1

A sensitive enzyme-linked immunosorbent assay (ELISA) based on immunomagnetic beads (IMB-ELISA) was established using a magnetic-bead signal-enrichment system. The immunomagnetic beads were coated with polyclonal antibody directed against keyhole limpet hemocyanin (KLH), which were then coupled with a KLH–fumonisin B1 (FB1) conjugate. Anti-FB1 monoclonal antibody and sample extract were mixed and added to the immunomagnetic-bead solution. After the addition of horseradish peroxidase (HRP)-labeled goat anti-mouse antibody and the substrate solution, stop solution was added and the optical density of the reaction mixture was determined. To improve the performance of this method, the dilution of the immunomagnetic beads, the concentrations of the monoclonal antibody and HRP-labeled goat anti-mouse antibody, and the incubation time for the competition reaction were optimized. Based on the optimum conditions, the regression equation for this IMB-ELISA in quantifying FB1 was y = −0.3538x + 0.703 (R² = 0.9988). The detection limit and IC₅₀ were 0.24 ng/mL and 3.17 ng/mL, respectively. The working range was 0.54–26.3 ng/mL. The recovery rates were 80.4–114.7%, when the spiked concentrations ranged from 19.5 to 156.3 μg/kg. This IMB-ELISA is accurate and more sensitive and less time-consuming than the conventional ELISA.