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In the present study, Graphene-TiO2 catalysts are prepared by solvothermal method with varied graphene concentrations (1%, 2.5% and 5%). The prepared nanocomposites were characterized by FTIR, Raman and TEM. The photocatalytic activity towards the destruction of Escherichia coli in water under UV and UV-visible irradiations were studied. Graphene-TiO2 nano composite destructs the bacteria significantly at higher rates than unmodified TiO2 and graphene. The results indicates that, at the beginning, the inactivation of E. coli cells is more due to the generation of reactive oxygen species (ROS) like, OH, H2O2, and O2– . Among all samples, the nano composite containing 2.5 wt.% of graphene exhibits a complete E. coli destruction in a minimum irradiation time of 15 and 20 min under UV–Visible and UV light irradiation respectively. The high photocatalytic activity is achieved with the optimum loading concentration of 2.5 wt. % graphene on titania
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Objective@#To effectively reduce the concentration of poisons in cleanroom, protect the health of workers, realize the optimization and automatic control of the new return air device. And the influence of initial concentration, air volume, temperature and relative humidity of formaldehyde on the purification effect of the new return air device was explored.@*Methods@#The purification effect of the new return air device installed with the activated carbon and the photocatalyst purification net or ordinary activated carbon purification network was tested in a 60 m3 simulated cleanroom. The concentration of formaldehyde was determined by solution absorption-phenol reagent spectrophotometry. Based on the single factor experiment to determine the combination of two purification nets. The effects of air volume, initial formaldehyde concentration, temperature and relative humidity on the purification effect of the new return air device were investigated by orthogonal test. Then, the performance parameters of the return air device to purify formaldehyde were determined.@*Results@#The formaldehyde purification efficiency of the two types of purification nets in the new return air device was higher than that of the ordinary activated carbon purification network (P<0.05) . The combination of activated carbon and photocatalyst purification net has no effect on the formaldehyde purification efficiency of the return air device (P>0.05) . According to the direct analysis and variance analysis, air volume was the most sensitive factor (F value is 18.894, P<0.05) , followed by initial concentration (F value is 16.128, P<0.05) , while temperature and relative humidity have little effect (F value is 0.041 and 0.599, respectively, P>0.05) . LSD analysis showed that there was no significant difference in the purification efficiency of formaldehyde between 475 m3/h and 626 m3/h (P>0.05) . From the perspective of formaldehyde purification efficiency and energy saving, when the air volume is set to 475 m3/h, the new return air device has higher purification efficiency for high concentration of formaldehyde.@*Conclusion@#The new return air device consisting of activated carbon and photocatalyst purification net can play a good purification role in cleanroom with different temperatures and different humidity. Its formaldehyde purification efficiency is affected by air volume and initial concentration.
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A large-scale pandemic by human influenza virus H1N1 in 2009 caused severe health, social, and economic impacts. In this study, a photocatalyst technology based on TiO2, was evaluated for inactivation of a human influenza virus H1N1 isolated from a patient. The virus titer was reduced by 103.16-fold within 24 h and more than 104.31-fold inactivation within 48 h and 72 h. These results suggest that the tested photocatalyst technology based on TiO2 can be used for reduction of influenza A virus adherence to other surfaces with Hizen-s inside diverse buildings, enabling effective control of its indirect contact infection. The photocatalyst is expected also to reduce level of the aerosol transmission of the virus.
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Humanos , Virus de la Influenza A , Gripe Humana , Pandemias , Carga Viral , VirusRESUMEN
Objective The generate of posterior capsular opacification(PCO)is associated with the adhensive and migration of residual subcapsular lens epithelial cells(LECs).Titanium dioxide(TiO_2)nanometer is proved to have the ability of killing tumor cells and cultured bovine LECs.This study tried to observe the effects of TiO_2 nanometer thin film provoked by light on adhesiveness and migration of bovine LECs in vitro.MethodsThe fresh bovine lenses were obtained and cultured in DMEM containing 10% of newborn bovine serum.The second to fifth generation of cells were used in this experiment.The slide modified by TiO_2 photocatalyst film was prepared by sol-gel method.Cultured cells were seeded in filmed or unfilmed slides respectively and exposed to ultraviolet(wavelength 365 nm)for 20 or 40 minutes.The contact angle between water drop and slide was measured by droping method and the cells adhered to slides were calculated after 24 and 48 hours of culture.The growth status and migration distance of bovine LECs were assayed and compared between filmed and unfilmed groups.ResultsThe contact angle between water drop and slide was 0°±2°and 18.825°±2.342° in filmed and unfilmed group respectively,indicating a obviously smaller contact angle in TiO_2 filmed group than unfilmed one.The numbers of bovine LECs adhered to filmed slide was considerably reduced in TiO_2 filmed group compared with unfilmed group in different UVA exposure time(t_(0 min)=5.492,P=0.001;t_(20 min)=6.031,P=0.000;t_(40 min)=6.828,P=0.000).However,no significant difference was found in the numbers of adhensive cells among 3 UVA irradiation time points(F=1.278,P=0.297).The migration distance of the cells was significantly shorter in TiO_2 filmed group in comparison with unfilmed group in 24 and 48 hours after UVA irradiation(F_(group)=14.965,P=0.000;F_(time)=38.033,P=0.000).ConclusionThe TiO_2 nanometer thin film is characterized by the superhydrophilic property.So it can effectively impede the adhesion and migration of bovine LECs in vitro.
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BACKGROUND: Titanium dioxide (TiO2) thin film photocatalyst generates strong oxidizing power when illuminated with Ultra Violet (UV) light with wavelengths of less than 385 nm. In this study, we evaluated the bactericidal activity of it against Escherichia coli, Aspergillus fumigatus and Mycobacterium tuberculosis. METHODS: The TiO2 film were prepared from titanium isopropoxide solution and it was coated on either inner(test) or outer(control) side on Petri dish. annealing at 500 degrees C. The test and control suspension of E. coli, A. fumigatus and M. tuberculosis were grown in the chamber coated inner and outer side. respectively with UV light. For the blank, cell suspensions were grown in TiO2 coated Petri dishes without UV light. The bactericidal activities were estimated by survival ratio calculated from the number of viable cells which form the nutrient agar. RESULTS: In the test, the survival ratio for E. coli and M tuberculosis decreased to a negligible level (i.e., essentially complete sterilization) within 1hr and 2 hr, respectively. and that for 11. fumigatus decreased markedly to about 15% within 6 hr. In the control, the survival ratio for E. coli, A. fumigatus and M. tuberculosis decreased to 40% within 150 min. 6 he and 2 hr, respectively. In the blank, the survival ratio for E. coli and M tuberculosis decreased only about 67% within 150 min and 40% within 2hr. In A. fumigatus, TiO2 only caused little Sterilization within 4 hr. CONCLUSIONS: TiO2 photocatalysts under UV light clearly showed bactericidal activity against E. coli, A. fumigarus and M. tuberculosis. This feature render TiO2 photocatalysts to be applicable to eliminate microorganism from indoor air environment combined with ventilation.