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A compact and high-performance shielding enclosure designed by metamaterial structure based on frequency selective surface (FSS) is proposed. The enclosure has large holes for convenience of airflow and cable access. However, it can achieve great shielding performance by maintaining more than 40 dB attenuation. The shield is composed of n ×× n unit cells, and each unit cell is designed by knitting the 2.5-dimensional loop-type elements interconnected through vias. This design shows promising capability of size reduction, bandwidth expansion, and shielding effectiveness enhancement. Moreover, the enlarged holes on the FSS are helpful for the ventilation and heat dissipation. The size of the proposed 2.5-D FSS is only 0.097λ0λ0××0.097λ0λ0, where λ0λ0 corresponds to free space wavelength of resonance frequency. The proposed structure provides 3.38 GHz (3.21–6.59 GHz) wide shielding bandwidth. Furthermore, it has stable response to the wide-angle incident wave ranging from 0∘∘ to 85∘∘ with more than 40 dB attenuation at 4.83 GHz for both x-polarization and y-polarization. The proposed FSS is practically useful for the shielding of fifth generation (5G) wireless systems, WiMAX, and WLAN.

BACKGROUNDPulmonary edema is a severe complication in patients with acute myocardial infarction which indicates the development of heart failure (HF) and poor prognosis. However, subclinical pulmonary edema after acute ST-segment elevation myocardial infarction (STEMI) without HF has not received enough attention in clinical practice. We aimed to investigate the prognostic value and associated clinical characteristics of subclinical pulmonary edema after acute STEMI without HF detected by chest computed tomography (CT).METHODSA total of 276 patients with acute STEMI without HF who underwent chest CT were included in this study. K-means clustering analysis was performed to classify the patients into different subgroups based on the mean lung density. Clinical characteristics of the different subgroups were compared and used to establish a machine learning model for discriminating between them. Relative risk (RR) for major adverse cardiovascular events (MACEs) during hospitalization was compared between the subgroups.RESULTSThe patients were classified into two subgroups. Subgroup 2 showed higher mean lung density than subgroup 1 (median [IQR], −727 [−747, −704] vs. −806 [−826, −785] HU, P < 0.001), with significantly higher levels of cardiac enzymes and numbers of inflammatory cells and significantly worse left ventricular function than subgroup 1. In the model analysis, the most important clinical characteristics were the levels of cardiac enzymes, numbers of inflammatory cells, and left ventricular function. The risk for MACEs was higher in subgroup 2 than in subgroup 1 (RR, 2.12; P = 0.002).CONCLUSIONSSubclinical pulmonary edema after acute STEMI without HF was mainly associated with elevated levels of cardiac enzymes, followed by increased numbers of inflammatory cells and worse left ventricular function. In addition, subclinical pulmonary edema provided crucial prognostic information for patients during hospitalization.

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