Background Transparent dressings are commonly used to cover central venous catheter sites. However, it has been suggested that they might not allow adequate moisture vapor transmission, resulting in local moistness th...Background Transparent dressings are commonly used to cover central venous catheter sites. However, it has been suggested that they might not allow adequate moisture vapor transmission, resulting in local moistness that promotes bacterial growth. We compared the moisture vapor transmission rates （MVTRs） of different, currently used transparent and traditional gauze dressings. We aimed to determine the MVTRs at different temperatures and humidities. Methods The dressings were used to seal 50-ml plastic centrifuge tubes containing 20 ml deionized water： Tubes in group 1 were covered with 12 layers of ordinary gauze, group 2 with IV3000, group 3 with OPSITE FLEXlGRID, group 4 with 3M HP Tegaderm, and group 5 with 3M Tegaderm. The tubes were placed upright in an artificial climate cabinet, so that the dressings were not touching the water, in order to simulate the conditions of medical dressings in contact with the skin. The average MVTRs were determined under different conditions. MVTRs were also determined with tubes from groups 2-5 laid on their sides, allowing the dressings to touch the water, so simulating contact of the dressings with sweating skin, or wounded skin with exudates. We also calculated the dressings＇ self-reactive abilities by comparing their MVTRs in contact with the water surface with those when not in contact with the water surface. Results Group 1 demonstrated the highest MVTR, followed by groups 2, 4, 3 and 5 under conditions simulating contact of the dressings with normal skin at the following temperatures and humidities： 20℃/30%, 20℃/60%, 20℃/90%, 37℃/30%, 37℃/60% and 37℃/90%. When the relative humidity （RH） increased, the MVTRs decreased. The MVTRs differed significantly among different dressings and RHs： At high temperature （37℃） and high humidity （90%）, the MVTR of the transparent dressings in group 2 was higher than that of group 1 （P 〈0.01）. The reactive MVTR was highest in group 2 （10.2-16.3 times 〉MVTR） while that of group 4 was second highest （2.6-9.6 times 〉MVTR）. Conclusions RH and temperature had significant effects on the MVTRs of different dressings. The IV3000 transparent dressing used in group 2 was as effective as ordinary gauze. These results suggest that increased infection rates due to low MVTRs might not be a problem. The clinical implications of these observations for catheter-related infections need to be further investigated in multicenter studies.展开更多
In the five-level K-type atomic system, by using another control field to couple the excited level of the coupling transition to the sixth higher excited level, a six-level atomic system is constructed. In this system...In the five-level K-type atomic system, by using another control field to couple the excited level of the coupling transition to the sixth higher excited level, a six-level atomic system is constructed. In this system, the multiple electromagnetically induced two-photon transparency has been investigated. What is more, if choosing the parameters of the control fields properly the triple transparency window will reduce to a double one which means that the multiple electromagnetically induced two-photon transparency can be manipulated in this system. The physical interpretation of these phenomena is given in terms of the dressed states and the dark states.展开更多
文摘Background Transparent dressings are commonly used to cover central venous catheter sites. However, it has been suggested that they might not allow adequate moisture vapor transmission, resulting in local moistness that promotes bacterial growth. We compared the moisture vapor transmission rates （MVTRs） of different, currently used transparent and traditional gauze dressings. We aimed to determine the MVTRs at different temperatures and humidities. Methods The dressings were used to seal 50-ml plastic centrifuge tubes containing 20 ml deionized water： Tubes in group 1 were covered with 12 layers of ordinary gauze, group 2 with IV3000, group 3 with OPSITE FLEXlGRID, group 4 with 3M HP Tegaderm, and group 5 with 3M Tegaderm. The tubes were placed upright in an artificial climate cabinet, so that the dressings were not touching the water, in order to simulate the conditions of medical dressings in contact with the skin. The average MVTRs were determined under different conditions. MVTRs were also determined with tubes from groups 2-5 laid on their sides, allowing the dressings to touch the water, so simulating contact of the dressings with sweating skin, or wounded skin with exudates. We also calculated the dressings＇ self-reactive abilities by comparing their MVTRs in contact with the water surface with those when not in contact with the water surface. Results Group 1 demonstrated the highest MVTR, followed by groups 2, 4, 3 and 5 under conditions simulating contact of the dressings with normal skin at the following temperatures and humidities： 20℃/30%, 20℃/60%, 20℃/90%, 37℃/30%, 37℃/60% and 37℃/90%. When the relative humidity （RH） increased, the MVTRs decreased. The MVTRs differed significantly among different dressings and RHs： At high temperature （37℃） and high humidity （90%）, the MVTR of the transparent dressings in group 2 was higher than that of group 1 （P 〈0.01）. The reactive MVTR was highest in group 2 （10.2-16.3 times 〉MVTR） while that of group 4 was second highest （2.6-9.6 times 〉MVTR）. Conclusions RH and temperature had significant effects on the MVTRs of different dressings. The IV3000 transparent dressing used in group 2 was as effective as ordinary gauze. These results suggest that increased infection rates due to low MVTRs might not be a problem. The clinical implications of these observations for catheter-related infections need to be further investigated in multicenter studies.
基金Project supported in part by the National Natural Science Foundation of China (Grant Nos 10775100 and 90503008)
文摘In the five-level K-type atomic system, by using another control field to couple the excited level of the coupling transition to the sixth higher excited level, a six-level atomic system is constructed. In this system, the multiple electromagnetically induced two-photon transparency has been investigated. What is more, if choosing the parameters of the control fields properly the triple transparency window will reduce to a double one which means that the multiple electromagnetically induced two-photon transparency can be manipulated in this system. The physical interpretation of these phenomena is given in terms of the dressed states and the dark states.
