Characterization of spatial-temporal distribution and microenvironment source contribution of PM2.5 concentrations using a low-cost sensor network with artificial neural network/kriging techniques.

Low-cost sensors (LCS) network is widely used to improve the resolution of spatial-temporal distribution of air pollutant concentrations in urban areas. However, studies on air pollution sources contribution to the microenvironment, especially in industrial and mix-used housing areas, still need to be completed. This study investigated the spatial-temporal distribution and source contributions of PM2.5 in the urban area based on 6-month of the LCS network datasets. The Artificial Neural Network (ANN) was used to calibrate the measured PM2.5 by the LCS network. The calibrated PM2.5 were shown to agree with reference PM2.5 measured by the BAM-1020 with R2 of 0.85, MNE of 30.91%, and RMSE of 3.73 µg/m3, which meet the criteria for hotspot identification and personal exposure study purposes. The Kriging method was further used to establish the spatial-temporal distribution of PM2.5 concentrations in the urban area. Results showed that the highest average PM2.5 concentration occurred during autumn and winter due to monsoon and topographic effects. From a diurnal perspective, the highest level of PM2.5 concentration was observed during the daytime due to heavy traffic emissions and industrial production. Based on the present ANN-based microenvironment source contribution assessment model, temples, fried chicken shops, traffic emissions in shopping and residential zones, and industrial activities such as the mechanical manufacturing and precision metal machining were identified as the sources of PM2.5. The numerical algorithm coupled with the LCS network presented in this study is a practical framework for PM2.5 hotspots and source identification, aiding decision-makers in reducing atmospheric PM2.5 concentrations and formulating regional air pollution control strategies.

Volvulus in pregnancy: a diagnostic dilemma.

In this case report, we describe a pregnant female patient at 27 weeks' gestation with a rare complication of volvulus. Her initial symptom was acute cramping pain of the lower right abdomen. Surgical intervention was performed under the impression of peritonitis. Pathologic diagnosis revealed volvulus of the mid ileum. The remainder of her pregnancy was uneventful. The physiologic changes of pregnancy may predispose the parturient to bowel obstruction due to compression of the gravid uterus against the intestine. If volvulus is suspected, then emergent surgery should be performed. Delays in treatment may result in septic shock and even death. We present this case to remind obstetricians of such rare causes of acute abdomen during pregnancy.

Primary jejunal leiomyosarcoma mimicking a gynecologic tumor.

Alimentary leiomyosarcoma (LMS) is not uncommon; however, LMS which metastasizes to the ovary and uterine serosa is extremely rare. We present a case diagnosed as LMS due to the negative finding on the CD117 stain, which is the most specific criterion for the differential diagnosis of gastrointestinal stromal tumor and LMS. Despite the daunting reoperation which was performed within a short interval in this case, the patient made a rapid recovery from both procedures.