RESUMEN
A coupled molecular dynamics (MD)-stochastic simulation based model has been proposed here for the thermal conductivity of ethylene glycol (EG) based copper nanofluid. The model is based on the thermal evolution of the nanoparticles dispersed in the nanofluid which is in contact with a heat source. It is natural that the nanoparticles dispersed in the nanofluid would move randomly by Brownian motion and repeatedly collide with the heat source. During each collision the nanoparticles would extract some heat by conduction mode from the heat source and this heat would be dissipated to the base fluid during Brownian motion by a combination of conduction and microconvection mode. Thus, in addition to normal conductive heat transfer through the base fluid (EG) itself (without nanoparticles) some amount of heat is transferred by the collision of the nanoparticles with the heat source. The extent of this additional heat transfer has been estimated in the present model to estimate the enhancement in thermal conductivity of EG based copper nanofluid, as a function of volume fraction loading of nanoparticles. The prediction of the present model has been compared with the experimental data available in literature, and it has shown a reasonable agreement between the theoretical prediction and the experimental data.
RESUMEN
One of the important features of correction of prominent ears involves the creation of an antihelical fold in the ear cartilage. The precise and symmetrical location of this fold is crucial for the aesthetic result. This study investigated the use of the fissura antitragohelicina, a constant anatomic landmark, as a guide to the correct line for the new antihelix. In the first part of the study, 16 cadaveric ears were dissected. The fissura antitragohelicina was present in each specimen, and measurements of the distance between the fissura antitragohelicina and the helix and the antihelix were recorded. Based on this study, a clinical series of 20 consecutive prominent ear corrections were performed using the fissura antitragohelicina as a guide for the creation of a new, symmetrical antihelical fold. The aesthetic results were satisfactory by subjective assessment in every one of this group of patients. This study showed that the fissura antitragohelicina was a constant, reliable, and simple guide to the creation of the antihelical fold in patients with prominent ears.
Asunto(s)
Cartílago Auricular/anatomía & histología , Oído Externo/anomalías , Oído Externo/cirugía , Adolescente , Niño , Preescolar , Femenino , Humanos , Masculino , Resultado del TratamientoRESUMEN
The purpose of this study was to compare methodologies for the preparation of human skin composites based on deepidermized acellular dermal matrix, epidermal keratinocytes, and dermal fibroblasts with the aim of preparing a clinically useful skin substitute. Dermal matrices were prepared from normal human skin and we compared methods of sterilization (glycerol treatment, ethylene oxide treatment, and gamma irradiation), methods of removing the epidermis (sodium chloride, phosphate buffered saline, and dispase), and methods of seeding the composites with fibroblasts and keratinocytes. We report protocols for reproducibly preparing composites that share many of the features of normal skin after 7 days culture at an air-liquid interface. Such composites can be based on allodermis pretreated with either glycerol or ethylene oxide (although the latter gave less consistent results than the glycerol treatment). Fibroblast penetration into the dermis could be achieved by culture of cells on the reticular or papillary surface of the dermis. However, we report for the first time that fibroblast entry from the papillary surface only occurred when keratinocytes were also present.
Asunto(s)
Trasplante de Piel , Piel Artificial , Diferenciación Celular/fisiología , Técnicas de Cultivo , Matriz Extracelular/patología , Fibroblastos/citología , Humanos , Queratinocitos/citología , Esterilización/métodos , Cicatrización de Heridas/fisiologíaRESUMEN
Glycerol has long been used for the preservation of skin allografts. The antimicrobial activity of glycerol has not been fully documented. This paper reports the results of an investigation of a model studying the effect of glycerol on the inactivation of intracellular viruses. Two viruses--herpes simplex type I (HSV-1) and poliovirus--were cultured within human dermal fibroblasts. These intracellular viruses were incubated with 50 per cent, 85 per cent and 98 per cent glycerol at 4 degrees C and 20 degrees C for 4 weeks. Each week, the cultures in glycerol and controls in fibroblast maintenance medium were assayed for virus infectivity by examining the ability of harvested viruses to infect further fibroblasts. At 4 degrees C, 85 per cent glycerol could not fully inactivate intracellular HSV-I or poliovirus even after 4 weeks; 98 per cent glycerol inactivated intracellular HSV-I (after 3 weeks) but could not fully inactivate intracellular poliovirus after 4 weeks. At 20 degrees C, 85 per cent glycerol inactivated intracellular HSV-I (within 1 week) but could not fully inactivate intracellular poliovirus after 4 weeks; 98 per cent glycerol inactivated intracellular HSV-I (within 1 week) and inactivated intracellular poliovirus (after 2 weeks). It is suggested that, on the basis of this study, glycerol can reduce intracellular virus infectivity but that its effects are very dependent on concentration, time and temperature such that we would recommend that allograft skin be exposed to 98 per cent glycerol for a minimum of at least 4 weeks at a minimum temperature of 20 degrees C before clinical use.
Asunto(s)
Glicerol/farmacología , Herpesvirus Humano 1/crecimiento & desarrollo , Poliovirus/crecimiento & desarrollo , Piel/virología , Conservación de Tejido , Cadáver , Células Cultivadas , Fibroblastos/virología , Herpesvirus Humano 1/efectos de los fármacos , Humanos , Poliovirus/efectos de los fármacos , Trasplante de Piel , TemperaturaRESUMEN
This study investigated the effect of short-term storage on the viability and in vitro attachment efficiency of cultured epithelial autograft sheets. Four storage protocols were investigated: overnight at 37 degrees C in keratinocyte culture medium, overnight at 4 degrees C in phosphate-buffered saline solution, overnight at -80 degrees C in cryopreservation medium (containing 10% dimethyl sulphoxide), and 1 week at -80 degrees C in cryopreservation medium. Viability was assessed before and after storage by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. All the storage conditions significantly reduced viability compared with fresh sheets, and no significant decrease was seen when the sheets stored under the different protocols were compared with each other. The best viability obtained was 60% of that of the fresh sheets. The in vitro viability of these stored sheets was then compared with that of the fresh sheets by culturing them on deepidermized acellular allodermis and assessing the composites formed by light microscopy and the MTT assay. The fresh sheets attached and formed a histologically demonstrable composite with the dermal substrate, whereas none of the stored sheets formed demonstrable composites. The MTT assay demonstrated that composites formed with the stored sheets had less than 10% viability compared with composites formed with fresh sheets. It is concluded that under the conditions of storage examined, the viability of cultured epithelial autograft sheets was significantly reduced, but up to 60% of viability could be retained in some cases. However, the subsequent in vitro attachment and proliferation of such preserved sheets on allogeneic deepidermized dermis was poor compared with that of fresh cultured epithelial autograft sheets.