Radon in Underground Mines

Radon, a radioactive noble gas, is a decay product of uranium found in varying concentrations in all soils and rocks in the earth crust. It is colorless, odorless, tasteless, and a leading cause of lung cancer death in the USA. A study of underground miners shows that 40% of lung cancer deaths may be due to radon progeny exposure. In underground mines, radon monitoring and exposure standards help in limiting miners’ exposure to radioactivity. Radon mitigation techniques play an important role in keeping its concentration levels under permissible limits. This chapter presents a review of the radon sources and monitoring standards followed for underground mines in the USA. Also, the different radon prediction and measurement techniques employed in the underground mines and potential mitigation techniques for underground mining operations are discussed.

Review of investigations into the vadose zone’s variable state of saturation in connection with the assessment of radon potential in Bulgaria

Natural radon (222Rn) is a radioactive noble gas that occurs as the immediate decay product of radium (226Ra), part of the 238U family, in the lithosphere. Radon is driven by advection and diffusion with soil gas throughout connected and water-unsaturated pores and/or cracks in permeable rocks and soils. The aim of the present study is to do a review of the existing so far research activities in Bulgaria in connection with the observation and/or evaluation of the degree of water saturation of the near-surface layer, and on that base to distinguish the up-to-date achievements in regards to the radon potential in situ evaluation. Due to this review, the studies in Bulgaria concerning moisture dynamics in the near-surface layers can be divided mainly into two groups. The first one investigates the hydraulic characteristics (parameters) of soils in the vadose zone. Based on that, conclusions or computer simulations for the saturation degree estimation can be drawn. The other group includes in situ observations by sensors on the change of moisture with time. The results of these studies may serve as a base for more precise moisture dynamics assessment at sites with specific radon potential tendencies.

Titan's Interior Structure and Dynamics After the Cassini-Huygens Mission

The Cassini-Huygens mission that explored the Saturn system during the period 2004–2017 revolutionized our understanding of Titan, the only known moon with a dense atmosphere and the only body, besides Earth, with stable surface liquids. Its predominantly nitrogen atmosphere also contains a few percent of methane that is photolyzed on short geological timescales to form ethane and more complex organic molecules. The presence of a significant amount of methane and 40Ar, the decay product of 40K, argues for exchange processes from the interior to the surface. Here we review the information that constrains Titan's interior structure. Gravity and orbital data suggest that Titan is an ocean world, which implies differentiation into a hydrosphere and a rocky core. The mass and gravity data complemented by equations of state constrain the ocean density and composition as well as the hydrosphere thickness. We present end-member models, review the dynamics of each layer, and discuss the global evolution consistent with the Cassini-Huygens data. ▪ Titan is the only moon with a dense atmosphere where organic molecules are synthesized and have sedimented at the surface. ▪ The Cassini-Huygens mission demonstrated that Titan is an ocean world with an internal water shell and liquid hydrocarbon seas at the poles. ▪ Interactions between water, rock, and organics may have occurred during most of Titan's evolution, which has strong astrobiological implications. ▪ Data collected by the Dragonfly mission and comparison with the JUpiter ICy moons Explorer (JUICE) data for Ganymede will further reveal Titan's astrobiology potential. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 49 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

STUDY OF THE TRANSFORMATION OF NITROSYL IRON COMPLEX WITH N-ETHYLTHIOUREA LIGANDS IN MODEL BIOLOGICAL SYSTEMS

The process of transformation of a mononuclear cationic complex with N-ethylthiourea ligands in Tris-HCl buffer, as well as in a reaction mixture with reduced glutathione and bovine serum albumin, has been studied. It was found that in the presence of glutathione, the complex dimer-izes, while its initial ligands are replaced by glutathione. In the presence of albumin, the decay product of the complex is coordinated with amino acid residues (Cys34 and His39) to form a protein-bound complex.

In-Service Transformer Oil Regeneration Based on Laboratory-Scale Process

This paper described in-laboratory oil regeneration process of aged transformer oil using adsorbent; Fuller’s earth. The niche of this paper is the usage of real aged transformer oil taken from an 11kV/433V in-service power transformer made by ACEC Transformer in 1986. The regeneration process is achieved by forcing a mixture of aged transformer oil and Fuller’s earth through a filter paper with the aid of a vacuum pump, hence producing reclaimed transformer oil. This oil was then inserted in an amber glass bottle, blanketed with nitrogen, tightly sealed, and labelled. To test the effectiveness of Fuller’s earth as adsorbent, parameters of Dissolved Decay Product (DDP) were measured using UV-Visible Spectrophotometer (UV-Vis) by referring to ASTM D6802. In addition, Total Acid Number (TAN) and Breakdown Voltage (BdV) measurement were carried out complying the ASTM D974 and ASTM D1816 respectively. Results of UV-Vis indicated that Fuller’s earth can adsorbed 25.24% of DDP in aged transformer oil. As the DDP decreased, TAN is 84.62% reduced while BdV increased 50%. These findings are parallel with the breakdown voltage mechanism due to acidity emergence. It is proved that Fuller’s earth is effective adsorbent for oil regeneration process.

The cos 2ϕ azimuthal asymmetry in ρ0 meson production in ultraperipheral heavy ion collisions

We present a detailed study of vector meson photoproduction in ultraperipheral heavy ion collisions (UPCs). Using the dipole model, we develop a framework for the joint impact parameter and transverse momentum dependent cross sections. We compute the unpolarized cross section and cos 2ϕ azimuthal angular correlation for ρ0 photoproduction with ϕ defined as the angle between the ρ0’s transverse momentum and its decay product pion meson’s transverse momentum. Our result on unpolarized coherent differential cross section gives excellent description to the STAR experimental data. A first compari- son between theoretical calculation and experimental measurement on the cos 2ϕ azimuthal asymmetry, which results from the linearly polarized photons, is performed and reasonable agreement is reached. We find out the characteristic diffractive patterns at both RHIC and LHC energies and predict the impact parameter dependent cos 2ϕ azimuthal asymmetries for ρ0 photoproduction by considering UPCs and peripheral collisions. The future experimental measurements at RHIC and LHC relevant to our calculations will provide a tool to rigorously investigate the coherent and incoherent production of vector meson in UPCs, as well as to probe the nuclear structure in heavy ion collisions.

Assessing the Impact of Housing Features and Environmental Factors on Home Indoor Radon Concentration Levels on the Navajo Nation

Uranium is naturally found in the environment as a radioactive metal element with high concentrations in the Southwestern US. In this region is the Navajo Nation, which spans approximately 69,930 square kilometers. A decay product of uranium is radon gas, a lung carcinogen that has no color, odor, or taste. Radon gas may pass from soil into homes; and, indoor accumulation has been associated with geographical location, seasonality, home construction materials, and home ventilation. A home and indoor radon survey was conducted from November 2014 through May 2015, with volunteers who reported residence on the Navajo Nation. Home geolocation, structural characteristics, temperature (°C) during radon testing, and elevation (meters) were recorded. Short-term indoor radon kits were used to measure indoor radon levels. 51 homes were measured for indoor radon levels, with an arithmetic mean concentration of 60.5 Becquerels per cubic meter (Bq/m3) (SD = 42.7). The mean indoor radon concentrations (Bq/m3) by house type were: mobile, 29.0 (SD = 22.9); wood, 58.6 (SD = 36.0); hogan, 74.0 (SD = 0.0); homes constructed of cement and wood, 82.6 (SD = 3.5); and homes constructed of concrete and cement, 105.7 (SD = 55.8). A key observation is that house construction type appears to be associated with the mean home indoor radon concentration. This observation has been published in that the basic structural make-up of the home may affect home ventilation and therefore indoor radon concentration levels.