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David C. Shoults Nicholas J. Ashbolt 《International journal of hygiene and environmental health》2019,222(1):111-116
UV disinfection is a relatively simple and cost-efficient disinfection method, especially for in-home greywater treatment. In this study, a bench scale experiment was performed using a LED collimated UV-C beam with a peak wavelength of 256?nm to determine if potentially pathogenic bacteria such as Staphylococcus aureus may become enriched in a semi-recirculating greywater system with UV as the sole disinfection step. A statistically significant (P?<?0.001) decreasing trend in UV-C efficacy was observed between the 1st and 6th UV exposure-growth cycles of S. aureus (ATCC 25923), resulting in a 1.5 decrease in log10 removal (P?<?0.00000) by the 5th iteration. An eleven-point dose-response curve of the 7th iteration of S. aureus was estimated and compared to the dose-response curve of the original strain; due to a longer apparent shoulder period and a decay constant of lesser degree, the dose required for a 4-log reduction of the enriched S. aureus was estimated to be ~1.9 times greater (22.0?mJ?cm?2 versus 11.8?mJ?cm?2). However, experimental results with S. epidermidis (ATCC 12228) and two wild strains, S. aureus and S. warneri, exhibited no trend of increased resistance. UV doses exceeding 20?mJ?cm?2 are generally sufficient in achieving a 4-log reduction of bacteria in drinking water systems; however, the results exhibited in this study suggest that when recirculation is involved, there may be a need for UV doses exceeding what is necessary for a 4-log reduction to suppress the enrichment of strains which could pose a public health risk. 相似文献
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《Actas dermo-sifiliográficas》2022,113(8):792-803
UV filters are used daily by millions of people. Not all of these filters, however, are 100% biodegradable, and many wastewater treatments plants are ill-equipped to filter them properly. As a result, UV filters are increasingly reaching the environment. Various types have been detected in soil, continental water, oceans, and numerous organisms, including algae, corals, fish, mammals, and even land birds. In addition, some filters, benzophenone-3 and octocrylene in particular, are toxic to these organisms. Toxic effects include coral bleaching and interference with metabolic, enzymatic, and reproductive activities in practically all organisms. Preliminary data suggest that UV filters may be bioaccumulating in humans, as they have been detected in urine and breast milk. It should be noted, however, that research into the environmental impact of UV filters holds challenges and limitations. 相似文献
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《Actas dermo-sifiliográficas》2020,111(5):390-397
Background and objectiveThe minimal erythema dose (MED), an essential measurement in studies of skin photosensitivity, requires establishing MED values for specific populations, given genetic variation. Different ways to assess erythema are also relevant. We aimed to determine MED values in a sample of Colombian patients and correlations between MED and Fitzpatrick skin type. We also studied concordance correlation between MEDs and two alternative ways to assess erythema.Patients and methodsCross-sectional study of 113 individuals in Bogotá, Colombia. We used a solar simulator to measure UV-A radiation and combined UV-A and UV-B (UVA + UVB) radiation, o se podría suprimir este término porque UVA y UVB son términos conocidos for MED calculation. Narrowband UV-B (NBUVB) radiation was measured in a phototherapy cabin. Erythema was assessed visually and with a Mexameter MX 18 device.ResultsThe median MEDs of UVA + UVB radiation were 22 mJ/cm2 for Fitzpatrick skin types I and II, and 33 and 43 mJ/cm2, respectively, for types III and IV. The MEDs of UV-A radiation were 22, 42, 86, and 100 J/cm2 for types I, II, III, and IV, respectively. The MEDs of NBUVB light were 390, 550, 770, and 885 mJ/cm2 for the 4 skin types. The correlation between MEDs and skin types ranged from 0.5 to 0.69. Lin's concordance correlation coefficients between visual and Mexameter assessments of erythema were greater than 0.8 in all cases.ConclusionThis study allowed us to understand MED values for UV-A, UVA + UVB, and NBUVB according to different skin types in the Colombian population. Concordance correlation coefficients between the different methods of erythema assessment were very good. Correlations between MEDs and skin types were moderate to good. 相似文献
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Ganglion cyst of the temporomandibular joint 总被引:1,自引:0,他引:1
Seong-Gon Kim Byoung-Ouck Cho Yong-Chan Lee Sam-Pyo Hong Chang-Hoon Chae 《Journal of oral pathology & medicine》2003,32(5):310-313
We report a case of cystic lesion in a 37-year-old woman. The patient had an oval-shaped lesion adjacent to the temporomandibular joint. Thick fibrotic tissue and muscle were observed microscopically, but the epithelium lining was not observed. The lesion was diagnosed as a ganglion cyst. The patient's general medical history was non-contributory. High performance liquid chromatography (HPLC) and mass spectrophotometry (MS) revealed some proteins from the fluid in the lesion, such as a filaggrin precursor, dystroglycan, a polyprotein of the hepatitis C virus, and proteins originating from bacteria. The follow-up examinations revealed no recurrence. The probable pathogenesis of the lesion is discussed. 相似文献
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de Medeiros CL González-López S Bolaños-Carmona MV Sanchez-Sanchez P Bolaños-Carmona J 《European journal of oral sciences》2008,116(1):66-71
The aim of this study was to measure the demineralization capacity of 37% phosphoric acid on bovine enamel at different time-points after bleaching with 30% carbamide peroxide. Five, 4 × 4-mm sections were obtained from the enamel of 10 bovine incisors. After applying 30% carbamide peroxide (Vivastyle) for 90 min, specimens were stored in artificial saliva for 0, 24, 72 h, or 7 d and then immersed in 37% phosphoric solution. At 15, 30, 60, 90, and 120 s, 5-ml aliquots were extracted. A control group of specimens was not bleached. Ca2+ concentrations were measured by atomic absorption spectrophotometry. A larger amount of Ca2+ was extracted from enamel by phosphoric acid after the application of 30% carbamide peroxide. Twenty-four hours after bleaching, significantly more Ca2+ was extracted from bleached than from control specimens at all time-points, and this greater susceptibility to the action of the acid persisted for at least 1 wk after bleaching. 相似文献