Hot corrosion of modified Ti_3Al-based alloy coated with thin Na_2SO_4 film at 910 and 950℃ in air

The hot corrosion behaviour of a modified Ti3Al-based alloy under thin Na2SO4deposit film was investigated at910and950°C in air.The corrosion product was identified by XRD and its morphologies on the surface and cross-section were observed bySEM.The alloy suffered from considerable hot corrosion attack.The mass gain versus time curves obtained by TGA exhibited tworegions of different kinetics.The whole corroded layer consisted of loose and porous mixture oxides of TiO2,Nb2O5and Al2O3.Numerous small nodules of corrosion product were observed.An illustrative schematic was established to describe the formationprocess of such nodules.It seemed that the refractory oxides played a significantly important role in determining the development ofhot corrosion attack.

Clinical diagnostic value of color Doppler ultrasound in cicatricial healing of uterine incision in cesarean section

Objective:To explore the clinical diagnostic value of color Doppler ultrasound in caesarean section scar healing.Methods: The study time: From December 2016 to November 2017 in our hospital 106 cases of cesarean section after cesarean uterine scar diagnosis, Among them, 53 cases were in the test group, and 53 cases were better than those in the control group, All cesarean parturients were examined by color Doppler ultrasound through the transvaginal and transabdominal. The image features and accuracy of the diagnosis were observed.Results: after examination, the distance between the scar site and the internal cervical of the test group was closer than that of the control group, and the proportion of the posterior uterus in the test group was much higher than that in the control group. At the same time, there was no significant difference in the size of uterus, endometrial thickness, and follicular diameter between the two groups of parturients after the color ultrasound examination.Conclusion: for the poor healing uterus incision scar parts after cesarean section. The combination of vaginal and abdominal color Doppler ultrasonography has high accuracy and has a certain guiding role in clinical treatment. It can be widely applied in clinic.

Improvement of Photoluminescence of Perovskite CH_(3)NH_(3)PbI_(3) by Adding Additional CH3NH3I during Grinding

The organic-inorganic hybrid perovskite CH_(3)NH_(3)PbI_(3) has been a good candidate for many optoelectronic applications such as light-emitting diodes due to its unique properties.Optimizing the optical properties of the CH_(3)NH_(3)PbI_(3) material to improve the device performance is a hot topic.Herein,a new strategy is proposed to enhance the light emission of CH_(3)NH_(3)PbI_(3) phosphor effectively.By adding the reactant CH_(3)NH_(3)I powder in an appropriate proportion and simply grinding,the emission intensity of CH_(3)NH_(3)PbI_(3) is greatly improved.The advantages of the proposed method are swiftness,simplicity and reproducibility,and no requirement for a complex organic ligand.The mechanism of this phenomenon is revealed by x-ray diffraction,scanning electron microscopy,energy dispersive spectroscopy,photoluminescence,and temperature-dependent photoluminescence.This study offers a unique insight for optimizing the optical properties of halide perovskite materials.

Reconfigurable metasurfaces that enable light polarization control by light

Plasmonic metasurfaces have recently attracted much attention because of their novel characteristics with respect to light polarization and wave front control on deep-subwavelength scales.The development of metasurfaces with reconfigurable optical responses is opening new opportunities in high-capacity communications,real-time holograms and adaptive optics.Such tunable devices have been developed in the mid-infrared spectral range and operated in light intensity modulation schemes.Here we present a novel optically reconfigurable hybrid metasurface that enables polarization tuning at optical frequencies.The functionality of tuning is realized by switching the coupling conditions between the plasmonic modes and the binary isomeric states of an ethyl red switching layer upon light stimulation.We achieved more than 20°nonlinear changes in the transmitted polarization azimuth using just 4 mW of switching light power.Such design schemes and principles could be easily applied to dynamically adjust the functionalities of other metasurfaces.

Time-resolved imaging of mode-conversion process of terahertz transients in subwavelength waveguides

We studied the mode-conversion process of terahertz pulses from a planar subwavelength waveguide to a tilted rectangular subwavelength waveguide. An unusual wavefront rotation, which led to an extra conversion t ime, was observed using a time-resolved imaging t echnique. We Simula ted the mode conversion process by a finite-difference time-domain method, and the results agreed well with the experiments. According to the simulations, the conversion time was demonstrated to become longer as the tilt angle or width of the rectangular waveguide increased. This work provides the possibility to optimize the future high-speed communications and t erahertz integrated plat forms.