The thermal conductivity values of ordinary concrete can be adjusted to those prescribed in constructions by entraining air bubbles to reduce the density of concrete in order to achieve good thermal insulation. This p...The thermal conductivity values of ordinary concrete can be adjusted to those prescribed in constructions by entraining air bubbles to reduce the density of concrete in order to achieve good thermal insulation. This paper concerns the analysis of air bubble distribution in concrete obtained by micro X-ray μCT （computed tomography） and correlates it with its thermal conductivity （k）. The samples were prepared of ordinary concrete varying the density by air-entraining additives, ranging between 2,277 kg/m3 and 1,779 kg/m3, aiming to correlate the mechanical properties and k with the characteristics of the bubble distribution. The results show that air-entrainment leads to viable use of this material as sealer to achieve good thermal insulation, and it can be adjusted, but there seems to be a limit to air entraining. By analysis of the μCT images, it was possible to correlate the more quantity of bubbles of smaller diameter with the minor k, in dry or wet state, and to prove that there is a limit in the entrapped air content, and if it is exceeded, the coalescence occurs.展开更多
Compartment syndrome of the thigh is a rare condition, potentially resulting in devastating functional outcome. Increasing intracompartmental pressure which suppresses microcirculation and capillary perfusion may lead...Compartment syndrome of the thigh is a rare condition, potentially resulting in devastating functional outcome. Increasing intracompartmental pressure which suppresses microcirculation and capillary perfusion may lead to cellular anoxia and muscle ischemia. The muscle com- partments in the thigh have a more compliant fascia and blend anatomically into the open compartments of the pelvis, thus compensating higher volumes than the compartments in the lower leg. We present a previously unreported case in which the limb of a 36-year-old man was run over by a 25- ton truck. He presented with a sensomotor deficit in his left lower leg with full paralysis of the shank muscles and ab- sence of all foot pulses. CT scan showed a huge haematoma in the thigh with active bleeding out of the popliteal artery into the haematoma which has already expanded into the muscle compartments of the lower leg. The limb had a disas- trous compartment syndrome of the thigh and lower leg with disruption of the popliteal neurovascular bundle; however, no bones in the limb were fractured. A complete fasciotomy of all the lower limb muscle compartments was immediately performed. The artery was reconstructed with interposition of the smaller saphenous vein, which was al- ready interrupted through the initial trauma.展开更多
文摘The thermal conductivity values of ordinary concrete can be adjusted to those prescribed in constructions by entraining air bubbles to reduce the density of concrete in order to achieve good thermal insulation. This paper concerns the analysis of air bubble distribution in concrete obtained by micro X-ray μCT （computed tomography） and correlates it with its thermal conductivity （k）. The samples were prepared of ordinary concrete varying the density by air-entraining additives, ranging between 2,277 kg/m3 and 1,779 kg/m3, aiming to correlate the mechanical properties and k with the characteristics of the bubble distribution. The results show that air-entrainment leads to viable use of this material as sealer to achieve good thermal insulation, and it can be adjusted, but there seems to be a limit to air entraining. By analysis of the μCT images, it was possible to correlate the more quantity of bubbles of smaller diameter with the minor k, in dry or wet state, and to prove that there is a limit in the entrapped air content, and if it is exceeded, the coalescence occurs.
文摘Compartment syndrome of the thigh is a rare condition, potentially resulting in devastating functional outcome. Increasing intracompartmental pressure which suppresses microcirculation and capillary perfusion may lead to cellular anoxia and muscle ischemia. The muscle com- partments in the thigh have a more compliant fascia and blend anatomically into the open compartments of the pelvis, thus compensating higher volumes than the compartments in the lower leg. We present a previously unreported case in which the limb of a 36-year-old man was run over by a 25- ton truck. He presented with a sensomotor deficit in his left lower leg with full paralysis of the shank muscles and ab- sence of all foot pulses. CT scan showed a huge haematoma in the thigh with active bleeding out of the popliteal artery into the haematoma which has already expanded into the muscle compartments of the lower leg. The limb had a disas- trous compartment syndrome of the thigh and lower leg with disruption of the popliteal neurovascular bundle; however, no bones in the limb were fractured. A complete fasciotomy of all the lower limb muscle compartments was immediately performed. The artery was reconstructed with interposition of the smaller saphenous vein, which was al- ready interrupted through the initial trauma.
