ABSTRACT
Single crystalline ZnO nanoplatelet structures were synthesized via a hydrothermal process on the surface of GaN microparticles. Growth of ZnO seeded on the GaN surface promoted faster growth along the directions within the basal plane of the ZnO crystal structure, resulting in the formation of 2-dimensional nanoplates with a thickness less than a few tens of nanometers at most. Electrical conduction across an individual nanoplate was measured and found to be extremely sensitive to UV illumination and the surrounding atmospheric environment. Such electrical behaviors of the nanoplates were attributed to the dominance of the polar (0001) surfaces and the adsorption and desorption of the ambient gas molecules on these surfaces. Their coupling with conduction electrons near the surface is the critical factor responsible for the highly sensitive electrical properties of the nanoplate. Virtually the entire volume of the nanoplates is under the influence of the surface adsorbed molecules, which changes the electrical properties of the nanoplates extensively, depending on their environmental conditions. Combining the very high photocurrent to dark current ratio and the high effective resistance of the ZnO nanoplates reported in the present study, ultrasensitive photo-devices operating at very low power can be expected with the use of 2-dimensional nanoplates.
ABSTRACT
OBJECTIVE: To compare the diagnostic performance of computed tomography (CT) and the Alvarado score and to determine whether patient age and sex influence the use of CT and the Alvarado score for diagnosing acute appendicitis. MATERIALS AND METHODS: We retrospectively reviewed the CT scans and medical records of 372 patients who presented with right lower quadrant pain and underwent CT to rule out acute appendicitis.The population was classified by age and sex to determine its influence on the use of the Alvarado score and CT. Receiver operating characteristic analysis was used to calculate and compare the diagnostic performance of both modalities. RESULTS: The overall area under the receiver operating characteristic curves for CT and the Alvarado score was 0.965 (highly accurate) and 0.732 (moderately accurate), respectively. There was little effect of patient age and sex on diagnostic performance of CT. However, the diagnostic performance of the Alvarado score was variable according to the patient age and sex (lowest in older women). Furthermore, the overall sensitivity of the Alvarado score was too low (72.8%) for determining immediate surgical intervention. CONCLUSION: Clinical assessment using the Alvarado score should be supplemented with CT examination for accurate diagnosis of acute appendicitis in all patients who are suspected of acute appendicitis.
Subject(s)
Appendicitis/diagnosis , ROC Curve , Tomography, X-Ray Computed , Adolescent , Adult , Age Factors , Diagnosis, Differential , Diagnostic Techniques, Digestive System , Female , Humans , Male , Middle Aged , Retrospective Studies , Sensitivity and Specificity , Sex FactorsABSTRACT
Primary pulmonary malignant fibrous histiocytoma (MFH) is very rare, so only a few imaging features have been reported. We report one case of rapidly growing primary pulmonary MFH mimicking a partially thrombosed pulmonary artery aneurysm and its radiologic findings, including multidetector row computed tomography (MDCT), conventional angiography, and fluorodeoxyglucose-positron emission tomography CT ([18F] FDG-PET/CT). On multi-phasic MDCT, this mass mimicked a pulmonary artery aneurysm with partial thrombosis. However, pulmonary artery aneurysm was excluded and suggested as a hypervascular parenchymal mass by subsequent conventional angiography. On [18F] FDG-PET/CT, it was a highly metabolic mass, showing a maximal standard uptake value (SUV) 12.1. Although primary pulmonary MFH is very rare and has no specific imaging findings, our experience might be helpful to differentiate a hypervascular pulmonary mass.
