Efficacy evaluation of commercial disinfectants by using Salmonella enterica serovar Typhimurium as a test organism

The efficacies of six commercial disinfectants were evaluated by using Salmonella enterica serovar Typhimurium under simulated natural conditions such as sub-zero temperature, short disinfecting time, and surface type (uneven or smooth). We used a suspensionmodel test to determine the disinfecting efficacy under varying contact times (1, 5, 10, and 30 min) and temperatures (25℃, 4℃, 0℃, and −10℃). The bactericidal effect according to surface structure was measured by using a carriermodel test at 25℃ and −10℃. The effective concentrations of each disinfectant were fixed to give a disinfecting effect within a short time (< 1 min) at 25℃ and −10℃. The suspension model results revealed that bactericidal efficacy significantly dropped at low temperature for most of the disinfectants used; a sodium dichloroisocyanurate product showed the strongest efficacy. In the carrier test, bacterial load on a wooden surface was more difficult to remove than that on a stainless-steel surface. The results show that commercial disinfectant products vary in their disinfecting efficacy, which is affected by several field factors including temperature, contact time, and carrier material. Environmental conditions and surface type for disinfection should be considered prior to selecting an optimal disinfectant in the field.

The influence of fusing conditions on the surface structure and morphology of SP1 SiO_2 in dental resin composites / 实用口腔医学杂志

Objective: To evaluate the influence of fusing conditions on the surface structure and morphology of the SP1 SiO2. Methods:The SP1 SiO2 samples were sintered under 500, 650, 800, 950 and 1 100 ℃ at a rate of 250 ℃/h and maintained for 10, 30 min, 3 h respectively. The surface structure was characterized by FT-IR. Results:The characteristic peak of Si-OH bond at 958 cm-1 took off gradually with the rising temperature and prolonged time. Under the conditions of 950 ℃ maintained for 10 min and 30 min, and 650 ℃ maintained for 3 h, it disappeared completely. The particles of the SP1 SiO2 became larger while the size distribution became narrow. Conclusion: Fusing conditions can affect the Si-OH content and the size of the SP1 SiO2, as well as the size of distribution.[