RESUMEN
Plastic scintillation detectors have practical advantages in the field of dosimetry. Energy calibration of measured gamma spectra is important for dose computation, but it is not simple in the plastic scintillators because of their different characteristics and a finite resolution. In this study, the gamma spectra in a polystyrene scintillator were calculated for the energy calibration and dose computation. Based on the relationship between the energy resolution and estimated energy broadening effect in the calculated spectra, the gamma spectra were simply calculated without many iterations. The calculated spectra were in agreement with the calculation by an existing method and measurements.
Asunto(s)
Plásticos , Radiometría/métodos , Conteo por Cintilación/instrumentación , Conteo por Cintilación/métodos , Calibración , Rayos gamma , Cinética , Modelos Estadísticos , Método de Montecarlo , Distribución Normal , Fotones , Poliestirenos/química , Dosis de Radiación , Reproducibilidad de los ResultadosRESUMEN
We demonstrate a new design concept where the interaction between silica nanoparticles (about 1.5 nm in diameter) with titania nanoparticles (anatase, about 4 nm or 6 nm in diameter) guides a successful formation of mesoporous titania with crystalline walls and controllable porosity. At an appropriate solution pH (~1.5, depending on the deprotonation tendencies of two types of nanoparticles), the smaller silica nanoparticles, which attach to the surface of the larger titania nanoparticles and provide a portion of inactive surface and reactive surface of titania nanoparticles, dictate the direction and the degree of condensation of the titania nanoparticles, resulting in a porous 3D framework. Further crystallization by a hydrothermal treatment and subsequent removal of silica nanoparticles result in a mesoporous titania with highly crystalline walls and tunable mesopore sizes. A simple control of the Si/Ti ratio verified the versatility of the present method through the successful control of mean pore diameter in the range of 2-35 nm and specific surface area in the ranges of 180-250 m(2) g(-1). The present synthesis method is successfully extended to other metal oxides, their mixed oxides and analogues with different particle sizes, regarding as a general method for mesoporous metal (or mixed metal) oxides.
RESUMEN
BACKGROUND/AIMS: Although colorectal endoscopic submucosal dissection (ESD)-related perforation is not uncommon, the factors affecting clinical outcomes after perforation have not been investigated. This study was designed to investigate the factors influencing the clinical course of ESD-related colon perforation. METHODS: Forty-three patients with colorectal ESD-related perforation were evaluated. The perforations were classified as endoscopic or radiologic perforations. The patients' medical records and endoscopic pictures were analyzed. RESULTS: The clinical outcomes were assessed by the duration of nil per os, intravenous antibiotics administration, and hospital stays, which were 2.7±1.5, 4.9±2.3, and 5.1±2.3 days, respectively. Multivariate analyses revealed that a larger tumor size, ESD failure, specific endoscopists, and abdominal pain were independently related to a poorer outcome. The time between perforation and clipping was 15.8±25.4 minutes in the endoscopic perforation group. The multivariate analysis of this group indicated that delayed clipping, specific endoscopists, and abdominal pain were independently associated with poorer outcomes. CONCLUSIONS: Tumor size, ESD failure, abdominal pain, and the endoscopist were factors that affected the clinical outcomes of patients with colorectal ESD-related perforation. The time between the perforation and clipping was an additional factor influencing the clinical course of endoscopic perforation. Decreasing this time period may improve outcomes.
Asunto(s)
Enfermedades del Colon/etiología , Resección Endoscópica de la Mucosa/efectos adversos , Perforación Intestinal/etiología , Proteína C-Reactiva/metabolismo , Colonoscopía , Neoplasias Colorrectales/cirugía , Femenino , Humanos , Mucosa Intestinal/cirugía , Complicaciones Intraoperatorias/etiología , Masculino , Persona de Mediana Edad , Pronóstico , Estudios RetrospectivosRESUMEN
BACKGROUND: The development of total intravenous anesthesia in coronary artery bypass graft (CABG) surgery has led to increased interest in the use of combination of propofol and remifentanil. Early extubation in post-cardiac surgery reduces the length of stay in intensive care unit and hospital and costs. The purpose of this study is to evaluate which anesthetic factors affect awakening time after anesthesia. METHODS: We enrolled twenty patients of ASA physical status II or III, scheduled for CABG in this study. All patients received a standardized propofol/remifentanil anesthesia as an effect site target controlled infusion. We recorded times to awakening and tracheal extubation, duration of cardiopulmonary bypass (CPB) period, total time of anesthesia and operation. Also, we recorded dose of propofol, remifentanil, fentanyl and minimum body temperature during CPB. To predict the factors that affect awakening time as a dependent variable, we considered all measured parameters as independent variables, and analyzed multiple linear regressions. RESULTS: The mean time responded to verbal command was 216.5 +/- 124.8 minutes after end of surgery. Among several parameters, minimum body temperature during CPB (P = 0.001) and total time of anesthesia (P = 0.003) were considered as significant factors that influence awakening time after CABG. CONCLUSIONS: Minimum body temperature during CPB and the duration of anesthesia influence awakening time after CABG, significantly.