Six techniques are used to measure the exciton diffusion length as a function of systematic chemical modifications.

Water is a quintessential element for the survival of mankind. Its variety of uses means that it is always in a constant state of demand. The supply of water most primarily comes from large reservoirs of water such as lakes, streams, and the ocean itself. As such, it is good practice to monitor its quality to ensure it is fit for human consumption. Current water quality monitoring is often carried out in traditional labs but is time consuming and prone to inaccuracies. Therefore, this paper aims to investigate the feasibility of implementing an Arduino-based sensor system for water quality monitoring. A simple prototype consisting of a microcontroller and multiple attached sensors was employed to conduct weekly onsite tests at multiple daily intervals. It was found that the system works reliably but is reliant on human assistance and prone to data inaccuracies. The system however, provides a solid foundation for future expansion works of the same category to elevate the system to being Internet of Things (IoT) friendly.

The natural radioactivity of intertidal sediment samples collected from the beaches of Oman was investigated. Using gamma ray spectrometry, the activity concentrations of 226Ra, 232Th and 40K in the sediment samples were measured to have average values of 20.49 ± 3.50, 2.26 ± 0.60 and 44.83 ± 4.60 Bq kg-1 respectively. The activity levels reported are considerably lower than the worldwide average. The annual effective dose rate was estimated to be 0.015 mSv yr-1 on average. Additionally, the mean radium equivalent, external and internal indices were 26.89, 0.07 and 0.13 Bq kg-1 respectively which were well below the risk limits. Gamma and alpha radiation indices were computed to be less than unity and show no exceedance beyond the recommended level. Our results provide baseline data for radioactivity in intertidal sediment samples of Oman and show that intertidal beach sand does not pose significant radiological risk to human health.

Radioactivity levels of naturally occurring radionuclides at the coast of Brunei Darussalam were evaluated along with their dose rates. Twenty-six berm and intertidal sediment samples were measured using gamma-ray spectrometry. The mean activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in berm sediments were 10.07 ± 1.02 Bq/kg, below the minimum detectable activity, and 21.44 ± 1.23 Bq/kg, respectively, whereas for intertidal sediments they were 7.01 ± 0.87, 1.67 ± 0.15 and 4.99 ± 0.42 Bq/kg, respectively. With respect to the radiological health risk, the average hazard indices, absorbed gamma dose rate, effective dose equivalent, and excess lifetime cancer risk were found to be less than the global average. Calculation of the activity ratio showed that ⁴⁰K is the main source of radiation in the coastal sediments. Furthermore, the difference in radioactivity levels between the berm sediments and intertidal sediments collected at the same location was investigated. Finally, a standard geological terminology of the littoral zone profile is proposed for describing coastal samples for universal communication among researchers.