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Electron spin resonance (ESR) is a powerful tool for characterizing and manipulating spin systems, but commercial ESR spectrometers can be inflexible and designed to work in narrow frequency bands. This work presents a spectrometer built from off-the-shelf parts that, when coupled with easy-to-design resonators, enables ESR over a broad frequency range, including at frequencies outside the standard bands. It can operate at either a single frequency or at two frequencies simultaneously. The spectrometer is controlled by a field programmable gate array (FPGA), and new capabilities can be easily added by reconfiguring the FPGA and adding or swapping components. We demonstrate the capabilities of the spectrometer using the molecular nanomagnet Cr7Mn, including simultaneous ESR at frequencies separated by nearly 500 MHz. [ABSTRACT FROM AUTHOR]

Coronavirus disease 2019 (COVID-19) typically involves the respiratory system, but gastrointestinal involvement is common. Further, patients with severe COVID-19 are at high risk to develop gastrointestinal complications, including bowel ischemia, ileus, and deranged liver enzymes. We present the case of a 44-year-old woman with mild COVID-19 pneumonia who was in home isolation. Ten days after the isolation, the patient presented to the emergency department complaining of generalized abdominal pain that was sharp in nature and associated with nausea and recurrent episodes of vomiting. The patient did not complain of any respiratory symptoms. Physical examination showed diffuse tenderness with no clinical signs to suggest generalized peritonitis. The laboratory parameters showed normal hematological, renal, and hepatic profiles. No elevation in the inflammatory markers was observed. The amylase level was within the normal range. Abdominal computed tomography scan demonstrated the presence of misty mesentery with increased density of the mesentery with fat stranding encasing the mesenteric vessels along with mesenteric adenopathy. Such radiological features suggested the diagnosis of mesenteric panniculitis. Subsequently, intravenous corticosteroid therapy was initiated and the patient exhibited significant improvement after 24 hours. The patient was discharged after nine days of hospitalization. She was followed up after one month and she had no complaints. Mesenteric panniculitis is a rare idiopathic inflammatory condition involving the mesenteric adipose tissue. The case shed a light on the possible association of COVID-19 with mesenteric panniculitis. The clinical manifestations of mesenteric panniculitis are non-specific and imaging studies are essential to suggest the diagnosis., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Alyousef et al.)