Radon Concentration and Its Ventilation Dependence Measured in Some Dwellings of Debresina, Ethiopia
Abiy Tamiru Beshah,
Tesfaye Dagne Muhe
Issue:
Volume 5, Issue 3, September 2020
Pages:
34-38
Received:
21 October 2020
Accepted:
4 November 2020
Published:
19 November 2020
Abstract: Ionizing radiation has been proved a major stress that can induce carcinogenesis. Among these ionizing radiations the most significant one is radon which is a source of 43% of the annual dose averaged over the population of the world. If it is present in enhanced level beyond maximum permissible limit, it may cause lung cancer. In the present work a set of indoor radon measurements has been carried out in some houses of Debresina district, Ethiopia using cellulose nitrate LR-115 type-II plastic track detectors in the bare mode. The detectors were fixed in the houses for one month to be exposed with indoor radon from February to March 2018. Etching of detectors was done with 2.5 N NaOH solution for 75 minutes at 60°C in the Soil physics laboratory and counting of tracks recorded was done using optical microscope in the Department of Earth Science, Bahirdar University. It is found that the value of radon concentration in those dwellings ranges from 12.24 to 251.94 Bq/m3 with an average of 102.87 Bq/m3 and standard deviation of 81.97 Bq/m3. The annual effective dose rates are found to vary from 0.31 to 6.29 mSv y-1 with an average of 2.57 mSv y-1 and a standard deviation of 2.05 mSv y-1. The indoor radon concentration has been found to have strong correlation with the ventilation condition. Ventilated houses have shown less radon concentration than unventilated houses. Though most of the indoor radon concentration values measured are well within the recommended action level of ICRP, more than half of these values are above the new recommended level of WHO.
Abstract: Ionizing radiation has been proved a major stress that can induce carcinogenesis. Among these ionizing radiations the most significant one is radon which is a source of 43% of the annual dose averaged over the population of the world. If it is present in enhanced level beyond maximum permissible limit, it may cause lung cancer. In the present work ...
Show More
Methods for Joint Determination of the Surface Tension Coefficient of a Liquid and the Contact Angle of Wetting the Hard Surface
Issue:
Volume 5, Issue 3, September 2020
Pages:
39-42
Received:
4 November 2020
Accepted:
17 November 2020
Published:
27 November 2020
Abstract: This article is devoted to the development of fundamentally new methods for the experimental determination of the physical properties of substances - methods of their "joint determination", when not a single property is measured, but two physical properties connected with each other. For example, this is the coefficient of surface tension σ of the liquid and the contact angle θ of wetting the surface by it, which here act as parameters of capillary forces at the interface. The purpose of such methods is not so much a banal arithmetic increase in the obtained experimental data, as a significant increase in their determination accuracy by reducing the statistical error (variance). In such cases, we have the so-called methods of indirect (indirect) measurement, which in this case are based not on the measurement of σ and θ directly, but on the measurement of the height h and weight ∆W of the meniscus hanging on a vertical surface, and on the subsequent solution of the resulting system of two equations that are analytical expressions for h and ∆W (i.e., a system of two equations with two unknowns: σ and θ). In the case of using a Wilhelmy plate in the experiment, the solution of such a system of equations leads to explicit analytical expressions for both unknowns (σ and θ), and in the case of using a cylindrical filament in the experiment, analytical expressions for the unknowns are obtained in an implicit form: in this case, to determine the value of the boundary of the angle θ, a recursive formula is proposed.
Abstract: This article is devoted to the development of fundamentally new methods for the experimental determination of the physical properties of substances - methods of their "joint determination", when not a single property is measured, but two physical properties connected with each other. For example, this is the coefficient of surface tension σ of the ...
Show More
