An approach based on gamma backscattering technique to measuring the density of liquid using the low-intensity radioactive source.

This work aims to develop a practical solution to measure the density of a liquid. Two purposes of this study: (1) using a low-activity source to measure the density of a liquid, and (2) simplifying the experimental arrangement to reduce the size and weight of the measuring system. The proposed solution is to develop a measurement technique without both detector and source collimators, while it considers an appropriate technique for analyzing the backscattering spectrum. To validate the proposed method, we used two groups of liquid: one group of liquids with a certified density and one group of liquids collected from the market. For the first group, the obtained results showed that the relative errors between the measured density and the reference one are below 6.8% and the uncertainties in density are below 4%, which confirms the feasibility of the proposed approach. For the second group, the liquids collected from the market include 70 percent alcohol, cooking oil, saltwater, fresh milk, diesel oil, dishwashing liquid, machine oil, and wine. The results obtained show that the relative errors between the densities determined by the proposed method and densities determined by the traditional method using density kit are less than 4.3%, the uncertainties in density when using the proposed method are below 3.2%. These results initially confirm that the proposed solution is completely applicable in measuring the density of a liquid.

A study on the sensitivity of the measurement of liquid density at different scattering angles using a gamma scattering technique.

This study aims to evaluate the sensitivity of the measurement of liquid density at different scattering angles using a gamma scattering technique. To perform this, the linear calibration curves of the ratio R (R is the ratio of the area under a single scattering peak for a liquid relative to that for water) versus the liquid density were constructed at different scattering angles. The sensitivity of the measurement is defined as the slope coefficient of these linear calibration curves. The results obtained from the Monte Carlo simulation data showed that the sensitivity of the measurement at different scattering angles including 70°, 80°, 90°, 100°, 110°, 120°, 130°, and 140° changes in the range from 0.44 to 0.48. Also, the results obtained from the experiment when performing the measurements at scattering angles of 90°, 100°, 110°, and 120° ranged from 0.46 to 0.48. This confirms that the dependence of the sensitivity of the measurement on scattering angle is insignificant. Besides, for every experimental dataset, we used each of 8 above-obtained calibration curves, in turn, to determine the densities of 8 liquids which yield the relative deviation between the measured density and the reference one is mostly less than 5%, the relative deviation of remaining cases (64 of 256 measurements) is in the range of 5.0%-9.9%.

Antibiotics in Wastewater of a Rural and an Urban Hospital before and after Wastewater Treatment, and the Relationship with Antibiotic Use-A One Year Study from Vietnam.

Hospital effluents represent an important source for the release of antibiotics and antibiotic resistant bacteria into the environment. This study aims to determine concentrations of various antibiotics in wastewater before and after wastewater treatment in a rural hospital (60 km from the center of Hanoi) and in an urban hospital (in the center of Hanoi) in Vietnam, and it aims to explore the relationship between antibiotic concentrations in wastewater before wastewater treatment and quantities of antibiotics used in the rural hospital, over a period of one year in 2013. Water samples were collected using continuous sampling for 24 h in the last week of every month. The data on quantities of antibiotics delivered to all inpatient wards were collected from the Pharmacy department in the rural hospital. Solid-phase extraction and high performance liquid chromatography-tandem mass spectrometry were used for chemical analysis. Significant concentrations of antibiotics were present in the wastewater both before and after wastewater treatment of both the rural and the urban hospital. Ciprofloxacin was detected at the highest concentrations in the rural hospital's wastewater (before treatment: mean = 42.8 µg/L; after treatment: mean = 21.5 µg/L). Metronidazole was detected at the highest concentrations in the urban hospital's wastewater (before treatment: mean = 36.5 µg/L; after treatment: mean = 14.8 µg/L). A significant correlation between antibiotic concentrations in wastewater before treatment and quantities of antibiotics used in the rural hospital was found for ciprofloxacin (r = 0.78; p = 0.01) and metronidazole (r = 0.99; p < 0.001).