Enhanced 2-MIB degradation by UV-LED/chlorine process: reaction kinetics, wavelength dependence, influencing factors and degradation pathways.

The efficient removal of 2-Methylisoborneol (2-MIB), a typical odour component, in water treatment plants (WTPs), poses a great challenge to conventional water treatment technology due to its chemical stability. In this study, the combination of ultraviolet light-emitting diode (UV-LED) and chlorine (UV-LED/chlorine) was exploited for 2-MIB removal, and the role of ultraviolet (UV) wavelength was investigated systematically. The results showed that UV or chlorination alone did not degrade 2-MIB effectively, and the UV/chlorine process could degrade 2-MIB efficiently, following the pseudo-first-order kinetic model. The 275 nm UV exhibited higher 2-MIB degradation efficiency in this UV-LED/chlorine system than 254 nm UV, 265 nm UV and 285 nm UV due to the highest mole adsorption coefficient and quantum yield of chlorine in 275 nm UV. ·OH and ·Cl produced in the 275 nm UV/chlorine system played major roles in 2-MIB degradation. HCO3- and Natural organic matter (NOM), prevalent in water, consumed ·OH and ·Cl, thus inhibiting the 2-MIB degradation by UV-LED/chlorine. In addition, NOM and 2-MIB could form a photonic competition effect. The degradation of 2-MIB by UV-LED/chlorine was done mainly through dehydration and demethylation, and odorous intermediates, such as camphor, were produced. 2-MIB was degraded through the α bond fracture and six-membered ring opening to form saturated or unsaturated hydrocarbons and aldehydes. Four DBPs, chloroform (CF), trichloroacetaldehyde (TCE), trichloroacetone (TCP) and dichloroacetone (DCP), were mainly generated, and CF was the most significant by-product.

"I'm healthy, I don't have pain"- health screening participation and its association with chronic pain in a low socioeconomic status Singaporean population.

BACKGROUND: We sought to determine the association between chronic pain and participating in routine health screening in a low socioeconomic-status (SES) rental-flat community in Singapore. In Singapore, ≥ 85% own homes; public rental flats are reserved for those with low-income. METHODS: Chronic pain was defined as pain ≥ 3 months. From 2009-2014, residents aged 40-60 years in five public rental-flat enclaves were surveyed for chronic pain; participation in health screening was also measured. We compared them to residents staying in adjacent owner-occupied public housing. We also conducted a qualitative study to better understand the relationship between chronic pain and health screening participation amongst residents in these low-SES enclaves. RESULTS: In the rental-flat population, chronic pain was associated with higher participation in screening for diabetes (aOR = 2.11, CI = 1.36-3.27, P < 0.001), dyslipidemia (aOR = 2.06, CI = 1.25-3.39, P = 0.005), colorectal cancer (aOR = 2.28, CI = 1.18-4.40, P = 0.014), cervical cancer (aOR = 2.65, CI = 1.34-5.23, P = 0.005) and breast cancer (aOR = 3.52, CI = 1.94-6.41, P < 0.001); this association was not present in the owner-occupied population. Three main themes emerged from our qualitative analysis of the link between chronic pain and screening participation: pain as an association of "major illness"; screening as a search for answers to pain; and labelling pain as an end in itself. CONCLUSIONS: Chronic pain was associated with higher cardiovascular and cancer screening participation in the low-SES population. In low-SES populations with limited access to pain management services, chronic pain issues may surface during routine health screening.

Primary care characteristics and their association with health screening in a low-socioeconomic status public rental-flat population in Singapore- a mixed methods study.

BACKGROUND: In Singapore, subsidized primary care is provided by centralized polyclinics; since 2000, policies have allowed lower-income Singaporeans to utilize subsidies at private general-practitioner (GP) clinics. We sought to determine whether proximity to primary care, subsidised primary care, or having regular primary care associated with health screening participation in a low socioeconomic-status public rental-flat community in Singapore. METHODS: From 2009-2014, residents in five public rental-flat enclaves (N = 936) and neighboring owner-occupied precincts (N = 1060) were assessed for participation in cardiovascular and cancer screening. We then evaluated whether proximity to primary care, subsidised primary care, or having regular primary care associated with improved adherence to health screening. We also investigated attitudes to health screening using qualitative methodology. RESULTS: In the rental flat population, for cardiovascular screening, regular primary care was independently associated with regular diabetes screening (adjusted odds ratio, aOR = 1.59, CI = 1.12-2.26, p = 0.009) and hyperlipidemia screening (aOR = 1.82, CI = 1.10-3.04, p = 0.023). In the owner-occupied flats, regular primary care was independently associated with regular hypertension screening (aOR = 9.34 (1.82-47.85, p = 0.007), while subsidized primary care was associated with regular diabetes screening (aOR = 2.94, CI = 1.04-8.31, p = 0.042). For cancer screening, in the rental flat population, proximity to primary care was associated with less participation in regular colorectal cancer screening (aOR = 0.42, CI = 0.17-0.99, p = 0.049) and breast cancer screening (aOR = 0.29, CI = 0.10-0.84, p = 0.023). In the owner-occupied flat population, for gynecological cancer screening, usage of subsidized primary care and proximity to primary care was associated with higher rates of breast cancer and cervical cancer screening; however, being on regular primary care followup was associated with lower rates of mammography (aOR = 0.10, CI = 0.01-0.75, p = 0.025). On qualitative analysis, patients were discouraged from screening by distrust in the doctor-patient relationship; for cancer screening in particular, patients were discouraged by potential embarrassment. CONCLUSIONS: Regular primary care was independently associated with regular participation in cardiovascular screening in both low-SES and higher-SES communities. However, for cancer screening, in the low-SES community, proximity to primary care was associated with less participation in regular screening, while in the higher-SES community, regular primary care was associated with lower screening participation; possibly due to embarrassment regarding screening modalities.