Orietation-controlled synthesis and Raman study of 2D SnTe.

Tin telluride (SnTe), as a narrow bandgap semiconductor material, has great potential for developing photodetectors with wide spectra and ultra-fast response. At the same time, it is also an important topological crystal insulator material, with different topological surface states on several common surfaces. Here, we introduce different Sn sources and control the growth of regular SnTe nanosheets along the (100) and (111) planes through the atmospheric pressure chemical vapor deposition method. It has been proven through various characterizations that the synthesized SnTe is a high-quality single crystal. In addition, the angular resolved Raman spectra of SnTe nanosheets grown on different crystal planes are first demonstrated. The experimental results showed that square SnTe nanosheets grown along the (100) plane exhibit in-plane anisotropy. At the same time, we use micro-nanofabrication technology to manufacture SnTe-based field effect transistors and photodetectors to explore their electrical and optoelectronic properties. It has been confirmed that transistors based on grown SnTe nanosheets exhibit p-type semiconductor characteristics and have a high response to infrared light. This work provides a new approach for the controllable synthesis of SnTe and adds new content to the research of SnTe-based infrared detectors.

Complications and feasibility analysis of ambulatory surgery for gynecological diseases in China.

ABSTRACT: The Chinese government is attaching great importance to the development of ambulatory surgery in order to optimize the healthcare system in China. The study aims to examine the complications and quality indicators of patients who underwent gynecological ambulatory surgery at a tertiary hospital in China.This was a retrospective study of patients who underwent ambulatory surgery between July and September 2019 at the Department of Gynecology of the First Affiliated Hospital of Shandong First Medical University. The patients were followed by phone at 30 days after discharge. The postoperative complications, mortality, unplanned re-operation, delayed discharge, unplanned re-hospitalization, and patient satisfaction were collected. The patients who underwent conventional hysteroscopic resection of uterine lesions during the same period were collected as controls for the economics analysis.A total of 392 patients who underwent ambulatory gynecological surgery were included. Fifteen patients had postoperative complications, and the total complication rate was 3.8% (15/392). Eight (8/392, 2.0%) patients had delayed discharge. There were no unplanned re-operations and deaths. There were two (2/392, 0.5%) cases of unplanned re-hospitalization. At 30 days after discharge, two patients were dissatisfied, and 390 cases were satisfied, for an overall satisfaction rate of 99.5%. Compared with conventional hysteroscopic resection of uterine lesions, ambulatory hysteroscopic surgery had a shorter hospital stay and lower total costs (P < .05) but similar surgery-related costs.Ambulatory gynecological surgery is feasible in China, with an acceptable complication profile and obvious economic and social benefits. Nevertheless, hospital management shall be reinforced.

Differentiation of chronic total occlusion and subtotal occlusion of the femoropopliteal artery-role of retrograde flow sign and collateral circulation on CT angiography images.

OBJECTIVE: To study the value of a retrograde flow sign and the collateral circulation on CT angiography (CTA) for the differential diagnosis of chronic total occlusion from subtotal occlusion of the femoropopliteal artery (FPA). 50 patients with obstruction of the FPA underwent CTA and digital subtraction angiography examinations of the lower limbs. The frequency of a retrograde flow sign and collateral circulation on CTA in chronic total and subtotal occlusion was noted and analyzed, with the results of digital subtraction angiography as a standard to judge total or subtotal occlusion. The decreasing CT value from the distal to proximal direction on CTA suggests the existence of retrograde flow. RESULTS: There were significant differences in the occurrence rates of a retrograde flow sign on CTA in the chronic total and subtotal obstruction groups (X2 = 13.1, p < 0.05), as well as a collateral circulation sign (X2 = 13.5, p < 0.05). Employing both the retrograde flow sign and the collateral circulation sign to diagnose chronic total obstruction of the FPA had a sensitivity of 92.3% and specificity of 89.8%. CONCLUSION: The retrograde flow sign combined with a collateral circulation sign is of great clinical value for differentiation of chronic total stenosis from severe stenosis (subtotal occlusion) of the FPA. Advances in knowledge: A retrograde flow sign combined with a collateral circulation sign is of great clinical value to differentiate between chronic total stenosis and severe stenosis (subtotal occlusion) of the FPA.