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2025
Our study aimed to assess air quality within buildings constructed with coal ash concrete, with a specific focus on radon measurement. Coal ash, a by-product of the TAQA Morocco thermal power plant. In this investigation, two concrete mixtures were prepared. It is possible that concrete produced from coal ash may contain elevated levels of radon, a naturally occurring radioactive gas that could prove detrimental to human health, given that coal ash contains considerable quantities of radioactive elements. To this regard, two nuclear techniques were employed for analysis: high-resolution gamma spectrometry and alpha dosimetry based on the use of LR115 on the two concrete mixes. The equivalent radium activity (Raeq), internal (Hin) and external (Hex) risk indices, absorbed dose rate (Ḋ), annual effective dose (Ė) and excess lifetime cancer risk (ELCR) were also calculated. The surface (ES) and mass (EM) radon exhalation rates were calculated for the analysed samples in order to assess the radiological risks resulting from the use of coal ash concrete.The results has revealed no evidence of any health risks to the general public, and therefore coal ash concrete can be used in construction projects.- Book : 601()
- Pub. Date : 2025
- Page : pp.00025-00025
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2025
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- Pub. Date : 2025
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2025
Indonesia has the potential to develop floating wind turbines at sea. Therefore, its movement response needs to be analyzed to ensure that the turbine works properly. This research aims to determine the floating offshore wind turbine barge’s movement response with different floater shapes to regular waves from three different directions (0°, 45°, 90°). The movement response of the floating wind turbine was analyzed using the diffraction and radiation analysis methods in Ansys Aqwa. The research results include the RAO curve for the structure in a couple of two degrees of freedom (heave-pitch) combined with 2-dimensional analyses. The motion response of the floater cube has a maximum value heave motion 0.999 m/m and pitch motion 2.228 °/m, and, the cylindrical shape has a heave motion 1.132 m/m and pitch 10.050 °/m. Lastly, the octagonal has a heave motion 1.010 m/m and pitch 2.565 °/m. The shape and volume of each model affect the response value obtained. The simulation results in this paper can provide considerations in selecting the right floater shape to be used as a wind turbine floater foundation.- Book : 601()
- Pub. Date : 2025
- Page : pp.00084-00084
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2025
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2025
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- Pub. Date : 2025
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2025
ABSTRACTPurposeThis study aimed to identify prognostic factors and develop a nomogram for survival in patients with brainstem ependymoma.MethodsData of 652 patients diagnosed with brainstem ependymoma extracted from the Surveillance, Epidemiology, and End Results (SEER) registry from 2000 to 2020 were analyzed. Univariate and multivariable Cox regression analyses were performed to examine factors influencing overall survival (OS). Receiver operating characteristic curve (ROC) and calibration curves were used to verify the nomogram. The Kaplan–Meier method was used to analyze OS based on treatment methods stratification or different age patterns.ResultsSix independent prognostic factors of patients with brainstem ependymoma were identified, including age, race, marital status, radiation, gross total resection (GTR), and histology. A comprehensive nomogram model was developed utilizing these predictors identified through multivariable Cox regression analysis. Furthermore, we found that patients with GTR have improved overall survival than patient with no surgery and biopsy only or with partial resection (GTR vs. no: p = 0.0004, GTR vs. partial resection: p = 0.022). Patients with radiation have improved overall survival than patient without radiation (p = 0.00013). Patients with GTR combined radiation therapy have improved overall survival than patient without or with GTR or radiation therapy only (p < 0.0001). Different treatment methods have no significant difference in the overall survival probability of the elderly group.ConclusionsIndividuals who are Black and anaplastic ependymomas were negative risk factors for brainstem ependymoma associated with an increased risk of mortality. Patients aged < 50 years with GTR and radiation always had better survival.- Book : 14(2)
- Pub. Date : 2025
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2025
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- Pub. Date : 2025
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2025
- Book : 13(01)
- Pub. Date : 2025
- Page : pp.163-172
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2025
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- Pub. Date : 2025
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2025
The cement-based materials widely used in infrastructure construction, such as bridges and ports, are subjected to seawater erosion and medium erosion during their service life, and their durability has always been a concern. The diffusion coefficient of chloride ions is an important indicator in the research of cement-based materials’ durability, and the pore structure is one of the most fundamental reasons affecting the diffusion behavior of chloride ions. In this paper, Mercury intrusion porosimetry (MIP), Nuclear magnetic resonance (NMR), and Nitrogen adsorption method (NAD) were used to analyze the pore structures of mortars with different volume fractions of sands. The relationship between mortar pore structure and chloride ion diffusion coefficient was established to predict its chloride ion diffusion coefficient. It may provide a new idea for studying the durability of cement-based materials. Results indicated that similar to cement paste, the pore structure of mortar satisfied the fractal characteristics of solid phase within a certain range of pores. The most probable gel pore diameter of mortars with different sand volume fractions was about 4 nm, while the most probable capillary pore diameter was approximately 46 nm, and the critical pore diameter was ranging from 50 to 60 nm. MIP results indicated that with the increase in sand volume fraction (ϕagg), the total porosity (fmip) of the mortar decreased, satisfying the relationship of fmip = 0.1859 − 0.0789ϕagg. However, the porosity of the matrix (fbase) increased with the increase in sand volume fraction, which was due to the introduction of more interfaces by the addition of aggregates. The effective chloride ion diffusion coefficient (Dcp,base) of the matrix can be obtained by fitting. Based on this, the interface transition zone (ITZ) and the cement matrix were comprehensively considered as a whole fractal phase. The predicted value of the chloride ion diffusion coefficient obtained by the Mori–Tanaka homogenization method was in good agreement with the results obtained from rapid chloride migration (RCM) experiments, and the maximum error between the simulated and experimental values did not exceed 11%. This finding can provide new ideas for accurately predicting the chloride ion diffusion coefficient of mortar and even concrete.- Book : 15(3)
- Pub. Date : 2025
- Page : pp.383-383
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