RESUMO
Porous 2D materials with high conductivity and large surface area have been proposed for potential electromagnetic interference (EMI) shielding materials in future mobility and wearable applications to prevent signal noise, transmission inaccuracy, system malfunction, and health hazards. Here, we report on the synthesis of lightweight and flexible flash-induced porous graphene (FPG) with excellent EMI shielding performance. The broad spectrum of pulsed flashlight induces photo-chemical and photo-thermal reactions in polyimide films, forming 5 × 10 cm2-size porous graphene with a hollow pillar structure in a few milliseconds. The resulting material demonstrated low density (0.0354 g cm-3) and outstanding absolute EMI shielding effectiveness of 1.12 × 105 dB cm2 g-1. The FPG was characterized via thorough material analyses, and its mechanical durability and flexibility were confirmed by a bending cycle test. Finally, the FPG was utilized in drone and wearable applications, showing effective EMI shielding performance for internal/external EMI in a drone radar system and reducing the specific absorption rate in the human body.
RESUMO
This paper presents a wide-angle scanning phased array antenna using high gain pattern reconfigurable antenna (PRA) elements. Using PRA elements is an attractive solution for wide-angle scanning phased array antennas because the scanning range can be divided into several subspaces. To achieve the desired scanning performance, some characteristics of the PRA element such as the number of switching modes, tilt angle, and maximum half-power beamwidth (HPBW) are required. We analyzed the required characteristics of the PRA element according to the target scanning range and element spacing, and presented a PRA element design guideline for phased array antennas. In accordance with the guideline, the scanning range was set as ±70° and a high gain PRA element with three reconfigurable patterns was used to compose an 8x1 array antenna with 0.9 λ0 spacing. After analyzing whether the active element patterns meet the guideline, the array antenna was fabricated and measured to demonstrate the scanning performance. The fabricated array can scan its beam from -70° to 70° by dividing the scanning range into three subspaces. It shows that even if the array antenna has large element spacing, the desired scanning performance can be obtained using the elements designed under the guideline.
RESUMO
Esophagogastroduodenoscopy (EGD) is considered a relatively safe procedure. However, the procedure and the materials used in EGD with conscious sedation can cause stress to the patient. Adverse events during EGD have been reported, represented by cardiopulmonary complications. To date, five cases have reported worldwide to be associated with gastrointestinal endoscopy. Stress cardiomyopathy (SCMP) is a reversible cardiomyopathy that typically occurs in postmenopausal women due to stress and may resolve within a few weeks. SCMP resembles acute myocardial infarction but differs in terms of treatment and prognosis. Here, we describe two cases of SCMP with shock during EGD with conscious sedation.
RESUMO
A 61-year-old male patient was admitted because of unexplained abdominal pain and anemia. His past medical history was unremarkable except for having taken herbal medicine to treat facial palsy two months ago. The result of health examination performed about a month ago showed increased serum aspartate and alanine aminotransferase level, and he was diagnosed with toxic hepatitis by herbal medicine. When the patient presented to the outpatient department three weeks ago, follow-up liver function test results showed improvement but he complained of abdominal pain. Despite extensive blood chemistry tests and computed tomography, the cause of pain could not be found. After much deliberation, serum lead level and herbal medicines analysis was performed based on the fact that he took herbal medicine two months ago, and he could finally be diagnosed with lead poisoning. Since the serum lead level was high enough to be indicated for lead chelating therapy, conservative management was given. When a patient with toxic hepatitis due to herbal medication presents with abdominal pain, the possibility of lead poisoning should always be taken into consideration.
