The objective of this study was to test the feasibility of a new method to improve the accuracy in the estimation of sewage
components. Adding to the regression of sewage components with UV (ultraviolet) absorbance values, a proposed method considered
an unclear but existing relationship among characteristic of sewage production. Sewage production showed very defined profiles
due to the daily human activities. So the main idea was the combination of measuring the UV absorbance values and analyzing
the characteristics of the sewage production. For this purpose, 446 sewage samples taken at every 2-h interval for 51 days
at a wastewater treatment plant were statistically analyzed using neural network (NN). NN was trained with 350 data sets (about
29 days) of UV absorbance values, flow rate and time. And as a result, it could predict 96 data (12 days) as a validation,
indicating that estimation accuracies were improved to higher level than those of the linear regressions. The proposed method
could estimate concentrations of total nitrogen (TN) and total phosphate (TP) within practical accuracies as well as total
suspended solid. 相似文献
This study reported the use of UV–visible and fluorescence spectroscopy and partial-least-square (PLS) multivariate regression for accurate and simultaneous quantifications of two widely used herbicides, propanil, 3′,4′-dichloropropionanilide (PPL) and bromoxynil, 3,5-dibromo-4-hydroxybenzonitrile (BXL) in human serum albumin (HSA) at physiological conditions. The binding affinity and thermodynamic properties of PPL-HSA and BXL-HSA complexes were also investigated. Partial-least-square (PLS) regression was used to collate the variability in the absorption or emission spectra of PPL-HSA and BXL-HSA complexes with PPL and/or BXL concentrations in HSA samples. The binding constants of 7.66× 108 M?1 for PPL-HSA and 4.88× 106 M?1 for BXL-HSA complexes were calculated at physiological conditions (temperature, 310 K; pH 7.4). Thermodynamic parameter values: enthalpy (ΔH) (13.99 kJ mol?1), entropy (ΔS) (0.078 kJ mol?1 K?1), and Gibbs free energy (ΔG) (?10.19 kJ mol?1) were determined for PPL-HSA complexation at physiological conditions. However, differences in thermodynamic property values of: ΔH (?214.3 kJ mol?1), ΔS (?0.563 kJ mol?1 K?1), and ΔG (?39.70 kJ mol?1) were observed for BXL–HSA complexes. The binding constants and negative ΔG values indicated strong binding affinity and thermodynamically favorability of PPL–HSA and BXL–HSA complex formation. Results of the PLS regression calibration showed good linearity (R2 ≥ 0.998289), high sensitivity, and impressive low limit-of-detections (LODs) of 1.38× 10?8 M for PPL and 1.68× 10?8 M for BXL that are comparable and/or lower than many previously reported LODs for herbicide and pesticide analyses. Most importantly, PLS regression is capable of simultaneous quantifications of PPL and BXL concentrations in HSA samples with good accuracy and low errors of 3.66%. UV–visible spectrophotometers and spectrofluorometers are fairly inexpensive, easy to use, and are readily available in almost every laboratory, making this protocol excellent and affordable for routine analysis of weed/pest control chemical residues in humans. The results of this study are significant and remarkable that will provide critical insight into the binding mechanism of herbicide toxicity in humans and non-target organisms, which are of special interest in the area of biomedical study, environmental risk assessment, and ecotoxicology. 相似文献
UV radiation is an alternative technology for the elimination of pathogenic micro-organisms in liquid food. The objectives of this work were to investigate mutagenesis using the Ames test in : (1) fresh squeezed orange juice submitted to UV radiation doses required to achieve 5 and 10 log10 reductions of different strains of Escherichia coli serotype O157:H7 at two temperatures, and (2) commercial pasteurized orange juice submitted to thermal treatment.
Two histidine-auxotrophic strains, Salmonella Typhimurium TA98 and TA97a, were used in the Ames test with and without metabolic activation.
In commercial pasteurized orange juices, mutagenesis was not observed with S. Typhimurium TA98 strain with and without metabolic activation, but high mutagenic effect was observed using TA97a with metabolic activation.
UV radiation did not affect the stability of ascorbic acid in aqueous solution. However, degradation of ascorbic acid was observed when UV treatment was performed on squeezed orange juice, following first order kinetics.
UV treatment required to achieve 5 log10 reductions (1.5 J/cm2) did not show a mutagenic effect with and without metabolic activation using the tested strains, but a higher UV radiation dose necessary to produce 10 log10 reductions (3.0 J/cm2) showed mutagenicity with metabolic activation. 相似文献
Degradation of perfluorooctanoic acid (PFOA) is of great importance due to its global distribution, persistence and toxicity to bioorganisms. In present study, a composite TiO2 with multiple wall carbon nano-tubes (MWCNTs) was synthesized using sol-gel method and it was used as photocatalyst to degrade PFOA in water. The prepared composite catalyst displayed significant absorption in UV to visible light region. The loading content of TiO2 on MWCNTs could be adjusted by changing the ratio of precursor to MWCNTs. Due to the combined effect of the adsorption ability and e− transport capacity of MWCNT, the composites displayed much higher photocatalytic ability to PFOA as compared to pure TiO2 under UV irradiation. The photocatalyst prepared with 10:1 of tetrabutyl titanate/MWCNT was the most effective. With the optimal dosage at 1.6 g L−1, almost 100% of PFOA was degraded in acid medium after irradiation for 8 h. It was proposed that PFOA were mainly degraded by stepwise losing a moiety of CF2. 相似文献
Two common freshwater phytoplankton species Microcystis aeruginosa and Scenedesmus obliquus were employed as test organisms to investigate the toxic effects of chlortetracycline widely used in human medicine and veterinary as antibiotic. Toxicity assays were performed into two parts: antibiotic toxicity test and antibiotic degraded products toxicity test. In general, chlortetracycline had significantly toxic effect on population growth and chlorophyll-a accumulation of two phytoplankton. Although M. aeruginosa had ability to grow after exposed to chlortetracycline at 0.5 mg L−1, its photosynthesis function was also disrupted. Compared with the data in two phytoplankton species, the chlorophyceae was more sensitive than the cyanophyceae. The adverse effect on S. obliquus was stronger than that on M. aeruginosa with increasing concentrations. In addition, for M. aeruginosa, regardless of the UV light degradation time, the treated chlortetracycline also had adverse effect on population growth and chlorophyll-a accumulated. The degraded chlortetracycline under any treatment time was more toxic for S. obliquus than chlortetracycline itself excluding under 24 h. However, the correlation between the toxicity and degradation time was not clear and toxicity enhanced in fact did not follow the increase or decrease in degradation time. Our study showed that the antibiotic chlortetracycline and its degraded products had adverse effect on freshwater phytoplankton, the former has not been reported before and the latter has been overlooked in other research in the past. 相似文献