Linear photogalvanic effects in monolayer WSe2 with defects.

Linear photogalvanic effects in monolayer WSe2 with defects are investigated by non-equilibrium Green's function technique combined with density functional theory. Monolayer WSe2 generates photoresponse in the absence of external bias voltage, showing potential applications in low-power consumption photoelectronic devices. Our results show that the photocurrent changes in perfect sine form with the polarization angle. The maximum photoresponse Rmax produced in the monoatomic S substituted defect material is 28 times that of the perfect material when the photon energy is 3.1 eV irradiated, which is the most outstanding among all the defects. Monoatomic Ga substitution extinction ratio (ER) is the largest, and its ER value is more than 157 times that of the pure condition at 2.7 eV. As the defects concentration increases, the photoresponse is changed. The concentrations of Ga substituted defects have little effect on the photocurrent. The concentrations of Se/W vacancy and S/Te substituted defect have a great influence on the photocurrent increase. Our numerical results also show that monolayer WSe2 is a candidate material for solar cells in the visible light range and a promising polarization detector material.

Linear photogalvanic effects in monolayer ternary metallic compound Na2MgSn.

The linear photogalvanic effect (LPGE) is investigated by using the non-equilibrium Green's function (NEGF) technique combined with density functional theory (DFT) in monolayer Na2MgSn. We consider the cases of three different central regions, which are pure Na2MgSn, Na-vacancy, and Pb-substituted. It is found that both pure and defective Na2MgSn monolayers induce photoresponse under linearly polarized light. The photoresponse varies periodically as a form of either sinusoidal or cosinoidal function of the polarization angle. In the near-infrared and visible ranges, the photoresponse is more sensitive to the long wave range of visible light. In the case of single-atom defects, the photoresponse with Na-vacancy is larger than that of pb-substitution defects. Compared with the other two central regions, the maximum extinction ratio (ER) of Na-vacancy is larger, so it has higher polarization sensitivity. When the location of Na-vacancy is adjusted, the photoresponse changes obviously, and the Na 1*- vacancy has the largest photoresponse. With the increase of the Na-vacancy concentration, the photoresponse changes nonlinearly but is smaller than that of a single vacancy. A small bias voltage can greatly improve the photoresponse. Our results suggest an effective method to enhance the photoresponse and show the promise of Na2MgSn monolayers in optical detection.

The Clinical Effect of Psychological Nursing on Patients Undergoing Coronary Angiography Based on Gold Nanoparticle Contrast Agents.

To study the clinical effect of psychological nursing on cardiovascular patients undergoing coronary angiography. Sixty cardiovascular patients in our hospital who needed coronary angiography were randomly divided into two groups (30 in each group); contrast agents based on gold nanoparticles were used for all patients. The experimental group received psychological nursing alongside conventional nursing care, and the control group received only conventional nursing care. The two groups were compared for ease of receiving coronary angiography, medical imaging, anxiety, depression, blood pressure, heart rate, efficacy, and patient satisfaction. A gold nanoparticle contrast agent has very low toxicity to cardiovascular endothelial cells, good biocompatibility, and a metabolic effect in vivo. Compared to the control group, the coronary angiography in the experimental group was easier; the medical images were clearer; patients' anxiety, depression, blood pressure, and heart rate decreased; and curative effect and patient satisfaction were higher. Psychological nursing may significantly improve the psychological and physical condition of cardiovascular patients undergoing coronary angiography, effectively improve the efficacy as well as satisfaction of patients, and has obvious application value in clinical treatment. Similarly, gold nanoparticle contrast agents have important value in the clinical application of coronary angiography.