Graphene Film Growth on Silicon Carbide by Hot Filament Chemical Vapor Deposition.

The electrical properties of graphene on dielectric substrates, such as silicon carbide (SiC), have received much attention due to their interesting applications. This work presents a method to grow graphene on a 6H-SiC substrate at a pressure of 35 Torr by using the hot filament chemical vapor deposition (HFCVD) technique. The graphene deposition was conducted in an atmosphere of methane and hydrogen at a temperature of 950 °C. The graphene films were analyzed using Raman spectroscopy, scanning electron microscopy, atomic force microscopy, energy dispersive X-ray, and X-ray photoelectron spectroscopy. Raman mapping and AFM measurements indicated that few-layer and multilayer graphene were deposited from the external carbon source depending on the growth parameter conditions. The compositional analysis confirmed the presence of graphene deposition on SiC substrates and the absence of any metal involved in the growth process.

Recurrencia de carcinoma papilar de tiroides en pacientes tiroidectomizados del Servicio Autónomo Oncológico del estado Lara / Recurrence of papillary carcinoma of thyroid in thyroidectomized patients from the Autonomous Oncological Service of Lara state

Con el objetivo de describir las recidivas de carcinoma papilar de tiroides (CPT) en pacientes tiroidectomizados atendidos en el Servicio Autónomo Oncológico del estado Lara, se realizó un estudio descriptivo transversal de recolección retrospectiva de datos de 140 historias clínicas de pacientes con diagnóstico de CPT registrados durante el lapso 2006-2017. Los pacientes incluidos se caracterizaron por un promedio de edad de 46,67 ± 13,94 años, siendo los más afectados los grupos de 41-50 años y 51-60 años; se observó un predominio del sexo femenino (86,33%). La intervención quirúrgica más realizada en estos pacientes fue la tiroidectomía total (44,29%) y tiroidectomía total con vaciamiento ganglionar (41,43%); 35,71% de los pacientes recibieron Iodo-131 como tratamiento adyuvante. El porcentaje de recidivas fue de 4,29%, siendo las recidivas más frecuentes la local y regional (33,33%, respectivamente); 66,67% de los casos de recidiva aparecieron en los primeros 5 años. De los pacientes con recidivas, 50% se les practicó tiroidectomía total y recibieron Iodo-131. Con estos resultados se aporta información epidemiológica actual sobre el CPT en nuestro centro con el fin de contribuir en la preparación de los servicios de cirugía y oncología para la atención de este grupo de pacientes(AU)

With the aim of describing the recurrences of papillary thyroid carcinoma in thyroidectomized patients treated at the Autonomous Oncology Service of Lara State, a cross-sectional descriptive retrospective study was conducted examining 140 medical records of patients with a diagnosis of papillary thyroid carcinoma registered during the period 2006-2017. Patients had an average age of 46.67 ± 13.94 years, being the most affected the 41-50 years and 51-60 years groups (26.43%, respectively); a predominance of females was observed (86.33%). The most performed surgical intervention was total thyroidectomy (44.29%) and total thyroidectomy with lymph node dissection (41.43%). Likewise, 35.71% received Iodine-131 as adjuvant treatment. The percentage of recurrences was 4.29%, being the most frequent local and regional with a prevalence of 33.33%, respectively; in addition, 66.67% of recurrences appeared during the first 5 years; 50% of these patients underwent total thyroidectomy and received Iodine-131. With these results, current information is provided in order to contribute to the preparation of surgical and oncological services for the care of cases of papillary thyroid carcinoma. It is important to maintain oncological follow-up in order to evaluate the evolution and prognosis of the different types of recurrences according to the place of appearance(AU)

Graphene Growth Directly on SiO2/Si by Hot Filament Chemical Vapor Deposition.

We report the first direct synthesis of graphene on SiO2/Si by hot-filament chemical vapor deposition. Graphene deposition was conducted at low pressures (35 Torr) with a mixture of methane/hydrogen and a substrate temperature of 970 °C followed by spontaneous cooling to room temperature. A thin copper-strip was deposited in the middle of the SiO2/Si substrate as catalytic material. Raman spectroscopy mapping and atomic force microscopy measurements indicate the growth of few-layers of graphene over the entire SiO2/Si substrate, far beyond the thin copper-strip, while X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy showed negligible amounts of copper next to the initially deposited strip. The scale of the graphene nanocrystal was estimated by Raman spectroscopy and scanning electron microscopy.

Synthesis, Characterization and Fabrication of Graphene/Boron Nitride Nanosheets Heterostructure Tunneling Devices.

Various types of 2D/2D prototype devices based on graphene (G) and boron nitride nanosheets (BNNS) were fabricated to study the charge tunneling phenomenon pertinent to vertical transistors for digital and high frequency electronics. Specifically, G/BNNS/metal, G/SiO2, and G/BNNS/SiO2 heterostructures were investigated under direct current (DC-bias) conditions at room temperature. Bilayer graphene and BNNS were grown separately and transferred subsequently onto the substrates to fabricate 2D device architectures. High-resolution transmission electron microscopy confirmed the bilayer graphene structure and few layer BNNS sheets having a hexagonal B3-N3 lattice. The current vs voltage I(V) data for the G/BNNS/Metal devices show Schottky barrier characteristics with very low forward voltage drop, Fowler-Nordheim behavior, and 10-4 Ω/sq. sheet resistance. This result is ascribed to the combination of fast electron transport within graphene grains and out-of-plane tunneling in BNNS that circumvents grain boundary resistance. A theoretical model based on electron tunneling is used to qualitatively describe the behavior of the 2D G/BNNS/metal devices.

Complicaciones postoperatorias en pacientes sometidos a tiroidectomía sin drenaje: Hospital Central Universitario Dr. Antonio María Pineda / Postoperative complications in patients subjected to drainage-free thyroidectomy: Hospital Central Universitario Dr. Antonio María Pineda

Con el objetivo de describir las complicaciones postoperatorias en pacientes sometidos a tiroidectomía sin drenaje que asistieron al Servicio de Cirugía General del Hospital Central Universitario Dr. Antonio María Pineda durante el lapso enero 2017-enero 2018, se realizó un estudio descriptivo transversal evaluando 142 historias donde los pacientes se caracterizaron por un promedio de edad de 50,23 ± 12,71 años, con predominio del sexo femenino (88%) y estado nutricional normal (58,45%). Los diagnósticos preoperatorios fueron carcinoma papilar variedad convencional (49,3%) y nódulo coloide (28,87%) mientras que los resultados histopatológicos fueron hiperplasia nodular (32,39%) y carcinoma papilar bien diferenciado (44,37%). Se registraron complicaciones postoperatorias en 48,59% pacientes siendo las más frecuentes la hipocalcemia transitoria (84,06%) y hematoma sofocante (2,90%) en las primeras 24 horas y seroma en la primera semana (16,42%); no hubo registro de complicaciones al mes. De acuerdo con las evidencias, la tiroidectomía realizada sin drenaje ha demostrado ser segura y no aumenta las complicaciones postoperatorias a las 24 horas, a la semana, ni al mes de la intervención(AU)

In order to describe the postoperative complications in patients undergoing undrained thyroidectomy who attended the Servicio de Cirugía General of the Hospital Central Universitario Dr. Antonio María Pineda during the period January 2017-January 2018, a cross-sectional descriptive study was conducted through the review of 142 medical charts; patients has an average age of 50.23 ± 12.71 years with predominance of the female sex (88.03%) and normal nutritional status (58.45%). The preoperative diagnoses were conventional papillary carcinoma (49.30%) and colloid nodule (28.87%); the histopathological results were nodular hyperplasia (32.39%) and well differentiated papillary carcinoma (44.37%). 48.59% of patients showed postoperative complications being transient hypocalcemia (84.06%) and suffocating hematoma (2.90%) the most common in the first 24 hours and seroma in the first week (16.42%); there were no reported complications one month after surgery. According to the evidence, thyroidectomy performed without drainage is safe and does not increase postoperative complications at 24 hours, a week, or a month after surgery(AU)