数字电子技术实验“线上-线下混合”教学改革

在“移动互联网+课堂”的大势趋动下,针对现在“数字电子技术实验”教学存在的教学模式落后,教学手段单一,教学内容简单、以及考核不够全面等问题,借助超星泛雅 “一平三端”平台进行“线上-线下混合教学”改革。通过课前发布任务、课中有效组织课堂活动、课后发布作业、统计数据和教学反思进行。实践表明：该方法提高了学生的自主学习能力,并且增强了教师对学生学习情况的动态跟踪和过程性指导,同时也让课堂教学更有效,教学评价方式更有针对性、更精准,最终达到知识、技能和情感态度价值观的培养。     

Synthesis and characterization of G/TiO1.80 bulk composite thermoelectric material under high temperature and high pressure

The primary purpose of this work is to introduce the second phase of graphene (G) into non-stoichiometric TiO_1.80 successfully and optimize the thermoelectric properties of this composite material through high pressure and high temperature (HPHT) technology. The purpose of doping Ti powder under high pressure is to create a closed reducing atmosphere to change the ratio of titanium to oxygen in the titanium oxide base. The addition of graphene can considerably improve the electrical properties of the material and reduce its resistivity. An X-ray diffractometer, X-ray photoelectron spectrometer, scanning electron microscope, and transmission electron microscope were used to analyze and characterize the phase structure, chemical bond, micro morphology and crystal morphology of the samples. An abundance of grain boundaries and lattice dislocation defects can inhibit the lattice thermal conductivity. We also tested and analyzed the thermoelectric performance of the high-temperature and high-pressure synthetic samples through a variable temperature system. The variation of the absorption intensity of the ultraviolet UV spectrum with wavelength shows that high pressure can reduce the band gap, which is beneficial to the carrier transition and improves the conductivity of semiconductors. HPHT optimizes both the electrical and the thermal parameters of the sample. At a final sintering pressure of 5.0 GPa, the dimensionless figure of merit (zT) of the bulk composite material G/TiO_1.80 was found to be 0.23 at 700 °C.     

浅谈电子电工技术在电力系统中的应用

本文针对电子电工技术在电力系统中的作用进行了分析,同时为该技术的推广提出了相应的建议。     

Transport properties in spinel ferrite/graphene oxide nanocomposites for electromagnetic shielding

Herein, $\left({\text{Co}}_{0.5}{\text{Ni}}_{0.5}\right){\text{Cr}}_{0.3}{\text{Fe}}_{1.7}{\text{O}}_4$/graphene oxide nanocomposites were fabricated by ultrasonication technique, using pure spinel ferrite and graphene oxide synthesized by sol-gel method and modified Hummers' method, respectively. The effect of graphene incorporation with ferrite nanoparticles was studied by X-ray diffraction (XRD), electrical and dielectric measurements. XRD analysis revealed the spinel phase for the ferrite sample and confirmed the formation of graphene oxide. The crystallite size was found in the range of $37-43\text{ nm}$ and the porosity increased with the increase in the concentration of graphene oxide in the composites. The DC electrical resistivity of spinel ferrite was found equal to $3.83\times {10}^9\text{ Ω}.\text{cm}$ and it substantially decreased with the increase in the percentage of graphene oxide at room temperature. The real and imaginary part of relative permittivity followed the Maxwell-Wagner type of interfacial polarization. AC conductivity confirmed the conduction by hopping mechanism and increased on increasing the GO content. The coupling of magnetic ferrite with graphene oxide tunes the magneto-electrical properties for potential applications at high frequencies.     

Design,preparation, and characterization of new high-refractive index hybrid organic–inorganic polysiloxanes: Innovative coatings for optoelectronic applications

The current demand for high-refractive index materials is very high due to their importance in optoelectronic applications. Such materials already exist in the market, but they present many disadvantages. They might contain toxic metals; their preparation can be challenging or produce high quantity of waste. Consequently, there is an urgent need to produce new friendly coatings with high-refractive index. Hybrid organic–inorganic polysiloxanes can offer a solution to this problem. They can be easily prepared from nontoxic alkoxy silanes using the sol–gel chemistry process. Herein, a series of new hybrid polysiloxanes are synthesized from the monomer 1–(2–(triethoxysilyl)ethyl)triphenylsilane and other silanes. The preparation of the macromolecules is optimized at both stages of the sol–gel process. The polymers are characterized by gel permeation chromatography and NMR spectroscopy. Spin coating of the materials on silicon wafers, followed by film thickness and refractive index measurements, indicates that the new polysiloxanes can have refractive indexes as high as 1.6 with thicknesses varying from 2200 to 3700 nm. Consequently, it is expected that the new materials described in this report are valuable for optoelectronic applications such as high-dielectric constant (high-k) gate oxides, interlayer high-k dielectrics, or high-refractive index abrasion resistant coatings.     

Structure–Function Relationship of Retinal Ganglion Cells in Multiple Sclerosis

The retinal ganglion cells (RGC) may be considered an easily accessible pathophysiological site of degenerative processes in neurological diseases, such as the RGC damage detectable in multiple sclerosis (MS) patients with (HON) and without a history of optic neuritis (NON). We aimed to assess and interrelate RGC functional and structural damage in different retinal layers and retinal sites. We included 12 NON patients, 11 HON patients and 14 healthy controls for cross-sectional multifocal pattern electroretinography (mfPERG) and optical coherence tomography (OCT) measurements. Amplitude and peak times of the mfPERG were assessed. Macula and disc OCT scans were acquired to determine macular retinal layer and peripapillary retinal nerve fiber layer (pRNFL) thickness. In both HON and NON patients the foveal N2 amplitude of the mfPERG was reduced compared to controls. The parafoveal P1 peak time was significantly reduced in HON only. For OCT, parafoveal (pfGCL) and perifoveal (pGCL) ganglion cell layer thicknesses were decreased in HON vs. controls, while pRNFL in the papillomacular bundle sector (PMB) showed reductions in both NON and HON. As the mfPERG derived N2 originates from RGC axons, these findings suggest foveal axonal dysfunction not only in HON, but also in NON patients.