ABSTRACT
Since the COVID-19 pandemic started, millions of peoples are involved. The presentation of the disease varies from mild respiratory symptoms and multiple organ failure to coma and death. Neurological symptoms such as headache or seizure are also coincident with COVID-19. Thromboembolic events increase in COVID-19 patients due to hypercoagulability and inflammation, particularly in severely ill patients. Thrombosis may cause venous thrombosis, pulmonary embolism, or cerebral sinus venous thrombosis (CSVT). Cerebral sinus venous thrombosis is a rare phenomenon that is usually found in critically ill patients with bad prognoses. In the present case report, we present a 40-year-old man with COVID-19 confirmed by real-time polymerase chain reaction (RT-PCR) who was admitted due to acute bilateral visual loss due to bilateral transverse sinus thrombosis. Pseudotumor cerebri disease was confirmed through high lumbar puncture. Early surgical intervention (optic nerve fenestration) was performed and, fortunately, his visual acuity improved. Cerebral sinus venous thrombosis is a rare incident in COVID-19 patients, but due to irreversible complications, an early diagnosis is fundamental. In any neurologic change in COVID-19 patients, CSVT must be considered. Also, prophylactic thrombolytic therapy should be kept in mind as the patient is admitted.
Desde o início da pandemia da COVID-19, milhões de pessoas estão envolvidas. A apresentação da doença varia desde sintomas respiratórios leves e falência de múltiplos órgãos até coma e morte. Sintomas neurológicos, como dor de cabeça ou convulsão, também coincidem com COVID-19. Os eventos tromboembólicos aumentam em pacientes com COVID-19 devido à hipercoagulabilidade e inflamação, particularmente em pacientes gravemente enfermos. A trombose pode causar trombose venosa, embolia pulmonar ou trombose venosa do seio cerebral (TVC). A trombose venosa do seio cerebral é um fenômeno raro, geralmente encontrado em pacientes gravemente enfermos e com mau prognóstico. No presente relato de caso, apresentamos um homem de 40 anos com COVID-19 confirmado por reação em cadeia da polimerase em tempo real (RT-PCR) que foi internado devido a perda visual bilateral aguda causada pela trombose bilateral do seio transverso. A doença pseudotumor cerebral foi confirmada através de punção lombar alta. Foi realizada intervenção cirúrgica precoce (fenestração do nervo óptico) e, felizmente, sua acuidade visual melhorou. A trombose venosa do seio cerebral é um incidente raro em pacientes com COVID-19, mas devido a complicações irreversíveis, um diagnóstico precoce é fundamental. Em qualquer alteração neurológica em pacientes com COVID-19, a TVCS deve ser considerada. Além disso, a terapia trombolítica profilática deve ser lembrada quando o paciente é internado.
ABSTRACT
Photoluminescence (PL) studies in GaN thin films grown by infrared close space vapor transport (CSVT-IR) in vacuum are presented in this work. The growth of GaN thin films was done on a variety of substrates like silicon, sapphire and fused silica. Room temperature PL spectra of all the GaN films show near band-edge emission (NBE) and a broad blue and green luminescence (BL, GL), which can be seen with the naked eye in a bright room. The sample grown by infrared CSVT on the silicon substrate shows several emission peaks from 2.4 to 3.22 eV with a pronounced red shift with respect to the band gap energy. The sample grown on sapphire shows strong and broad ultraviolet emission peaks (UVL) centered at 3.19 eV and it exhibits a red shift of NBE. The PL spectrum of GaN films deposited on fused silica exhibited a unique and strong blue-green emission peak centered at 2.38 eV. The presence of yellow and green luminescence in all samples is related to native defects in the structure such as dislocations in GaN and/or the presence of amorphous phases. We analyze the material quality that can be obtained by CSVT-IR in vacuum, which is a high yield technique with simple equipment set-up, in terms of the PL results obtained in each case.