Microstructural,magnetic and dielectric performance of rare earth ion(Sm^(3+))-doped MgCd ferrites

The combined effects of Sm^(3+)substitution together with the addition of 3 wt%Bi_(2)O_(3)endow Mg Cd ferrites with excellent magnetic permeability and dielectric permittivity.Various concentrations of Sm^(3+)(x=0,0.03,0.06,0.09,0.12and 0.15)were employed to modify the permeability(μ)and permittivity(ε)of the Mg Cd ferrites.X-ray diffraction,scanning electron microscopy(SEM),vibrating sample magnetometry and vector network analysis techniques were used to characterize the samples.The measurement results reveal that the ferrites processed a saturation magnetization of up to 36.8 emu/g and coercivity of up to 29.2 Oe via the conventional solid-state reaction method.The surface morphology SEM confirms that with increasing Sm^(3+)concentration,the grain shape changes from a polygon to a circle.Moreover,the dielectric permittivity can reach a value of 23.The excellent properties obtained in Sm^(3+)-substituted Mg ferrites suggest that they could be promising candidates for modern high-frequency antenna substrates or multilayer devices.

SERS activity of carbon nanotubes modified by silver nanoparticles with different particle sizes

A two-dimensional(2D)surface-enhanced Raman scattering(SERS)substrate is fabricated by decorating carbon nanotube(CNT)films with Ag nanoparticles(Ag NPs)in different sizes,via simple and low-cost chemical reduction method and self-assembling method.The change of Raman and SERS activity of carbon nanotubes/Ag nanoparticles(CNTs/Ag NPs)composites with varying size of Ag NPs are investigated by using rhodamine 6G(R6G)as a probe molecule.Meanwhile,the scattering cross section of Ag NPs and the distribution of electric field of CNTs/Ag NPs composite are simulated through finite difference time domain(FDTD)method.Surface plasmon resonance(SPR)wavelength is redshifted as the size of Ag NPs increases,and the intensity of SERS and electric field increase with Ag NPs size increasing.The experiment and simulation results show a Raman scattering enhancement factor(EF)of 108for the hybrid substrate.

Facial expression recognition based on fusion of extended LDP and Gabor features

The local directional pattern （LDP） is unsusceptible to random noise which is widely used in texture extraction of face region. LDP cannot encode the central pixel thus the important information will be lost. Thus a new feature descriptor called extended local directional pattern （ELDP） is proposed for face extraction. First, the mean value of the eight directional edge response values and the gray value of center pixel are calculated. Second, the mean value is taken as the threshold. Then, the expression image is encoded using nine encoded values. In order to reduce redundant information and get more effective information, the Gabor filter is used to obtain the multi- direction Gabor magnitude maps （GMMs） , and then the ELDP is used to encode the GMMs. Finally, support vector machine （SVM） is applied to classify and recognize facial expression. The experimental results show that the feature dimensions is greatly reduced and the rate of facial expression recognition is improved.

二维铟-VA族半导体:具有本征电场用于分解水的高效光催化剂

近年来,含有本征电场的二维半导体材料因拥有抑制光生载流子复合的潜在能力而受到了光催化领域研究人员的广泛关注.在本文中,我们采用第一性原理计算方法,报道了一类具有本征极性的新型二维半导体材料一单层铟-VA族化合物(ML-InXs;X=P、As和Sb),并探究了它们作为光催化剂分解水的可能.我们系统地研究了ML-InXs的几何结构、电子结构和光学性质,发现它们具有优异的结构稳定性、合适的带隙和带边位置、出色的载流子迁移率和较广的光吸收范围,因此可以成为水分解反应的优秀光催化剂.更重要的是,在ML-InXs中由本征偶极矩产生的电场可抑制光生电子-空穴对复合,大大提高了光催化反应过程中的能量转换效率.此外,我们发现应变工程可以有效地调节ML-InXs的带隙和光吸收,并显著提高它们分解水时的太阳能转化效率.我们的研究进一步加深了人们对具有本征电场的二维光催化剂的理解,并可为未来设计出具有优异性能的水分解或其他重要化学反应的光催化剂提供理论指导.