Influence of Cu and Ni on the morphology and composition of the rust layer of steels exposed to industrial environment

Four samples of steels with alloying elements were exposed to an industrial environment during 1,955 days, aiming to elucidate the effect of the alloying elements Cu and Ni on the resistance of weathering steels to corrosion processes. The samples were characterized with optical microscopy, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), saturation magnetization measurements and with energy dispersive (EDS), infrared, Mössbauer and Raman spectroscopies. All the steels originated orange and dark corrosion layers; their thicknesses were determined from the SEM images. EDS data of such rust layers showed that the alloying element content decreases from the steel core towards the outer part of the rust layer. Moreover, in the dark rust layer some light-gray regions were identified in the W and Cu-alloy steel, where relatively higher Cr and Cu contents were found. XRD patterns, infrared, Raman and Mössbauer spectra (298, 110 and 4 K) indicated that the corrosion products are qualitatively the same, containing lepidocrocite (γFeOOH; hereinafter, it may be referred to as simply L), goethite (αFeOOH; G), feroxyhite (δ′FeOOH; F), hematite (αFe₂O₃; H) and magnetite (Fe₃O₄; M) in all samples; this composition does not depend upon the steel type, but their relative concentrations is related to the alloying element. Mössbauer data reveal the presence of (super)paramagnetic iron oxides in the corrosion products. Saturation magnetization measurements suggest that feroxyhite may be an occurring ferrimagnetic phase in the rust layer.     

Variation of radon concentrations in soil and groundwater and its correlation with radon exhalation rate from soil in Budhakedar, Garhwal Himalaya

Radon was measured in soil-gas and groundwater in the Budhakedar area of Tehri Garhwal, India in summer and winter to obtain the seasonal variation and its correlation with radon exhalation rate. The environmental surface gamma dose rate was also measured in the same area. The radon exhalation rate in the soil sample collected from different geological unit of Budhakedar area was measured using plastic track detector (LR-115 type II) technique. The variation in the radon concentration in soil-gas was found to vary from 1098 to 31,776 Bq.m⁻³ with an average of 7456 Bq.m⁻³ in summer season and 3501 to 42883 Bq.m⁻³ with an average of 17148 Bq.m⁻³ in winter season. In groundwater, it was found to vary from 8 to 3047 Bq.l⁻¹ with an average value 510 Bq.l⁻¹ in summer and 26 to 2311 Bq.l⁻¹ with an average value 433 Bq.L⁻¹ in winter. Surface gamma dose rate in the study area varied from 32.4 to 83.6 μR.h⁻¹ with an overall mean of 58.7 μ-R.h⁻¹ in summer and 34.6 to 79.3 μR.h⁻¹ with an average value 58.2 μR.h⁻¹ in winter. Radon exhalation rate from collected soil samples was found to vary from 0.1 × 10⁻⁵ to 5.7 × 10⁻⁵ Bq.kg⁻¹.h⁻¹ with an average of 1.5 × 10⁻⁵ Bq.kg⁻¹.h⁻¹ in summer season and 1.7 × 10⁻⁵ to 9.6 × 10⁻⁵ Bq.kg⁻¹.h⁻¹ with an average of 5.5 × 10⁻⁵ Bq.kg⁻¹.h⁻¹. A weak negative correlation was observed between radon exhalation rate from soil and radon concentration in the soil. Radon exhalation rate from the soil was also not found to be correlated with the gamma dose rate, while it shows a positive correlation with radon concentration in water in summer season. Inter-correlations among various parameters are discussed in detail.      

Statistical relationship between activity concentrations of radionuclides 226Ra, 232Th, 40K,and 137Cs and geological formations in surface soil of Jordan

An extensive study was conducted to determine the activity concentrations of natural and artificial radionuclides ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs in soil samples of each governate of Jordan. A total of 370 samples have been measured using a high-purity germanium detector. The activity concentration for ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs has mean values of 42?±?3, 23?±?3, 309?±?21, and 3.7?±?0.9 Bq kg^–1, respectively. The highest mean activity concentration for ²²⁶Ra was found to be 138?±?4 Bq kg^–1 in the Alkarak governate. In the Ajloun and Jarash governates, the highest mean activity concentration was 35?±?3 Bq kg^–1 for ²³²Th, and 14.2?±?1.9 Bq kg^–1 for ¹³⁷Cs, respectively. Geological influence on the activity concentrations was investigated using the one-way analysis of variance (ANOVA) and independent samples. The ANOVA results indicate that there are strong significant differences between the activity concentrations of ²³²Th, ⁴⁰K, and ¹³⁷Cs based on geological formations the radionuclides occur. The main contribution to gamma dose rate was due to ²²⁶Ra activity concentration. Radium equivalent and external hazard index are associated with a mean value of 98 Bq kg^–1, and 0.266, respectively.     

Preparation of nano-hydroxyapatite particles with different morphology and their response to highly malignant melanoma cells in vitro

To investigate the effects of nano-hydroxyapatite (HA) particles with different morphology on highly malignant melanoma cells, three kinds of HA particles with different morphology were synthesized and co-cultured with highly malignant melanoma cells using phosphate-buffered saline (PBS) as control. A precipitation method with or without citric acid addition as surfactant was used to produce rod-like hydroxyapatite (HA) particles with nano- and micron size, respectively, and a novel oil-in-water emulsion method was employed to prepare ellipse-like nano-HA particles. Particle morphology and size distribution of the as prepared HA powders were characterized by transmission electron microscope (TEM) and dynamic light scattering technique. The nano- and micron HA particles with different morphology were co-cultured with highly malignant melanoma cells. Immunofluorescence analysis and MTT assay were employed to evaluate morphological change of nucleolus and proliferation of tumour cells, respectively. To compare the effects of HA particles on cell response, the PBS without HA particles was used as control. The experiment results indicated that particle nanoscale effect rather than particle morphology of HA was more effective for the inhibition on highly malignant melanoma cells proliferation.     

Cosmogenic beryllium-7 in soil,rainwater and selected plant species to evaluate the vegetal interception of atmospheric fine particulate matter

Beryllium-7 is a radionuclide produced in the upper atmosphere by cosmic-ray spallation with ions of carbon, oxygen and nitrogen. It is one of radionuclides that can be used to trace the fine particulate matter of 2.5-µm diameter (PM_2.5) and smaller. In this work, ⁷Be was determined in leaves of 10 plant species collected from streets, parks and open land and in 5 consecutive rains over Alexandria, Egypt. ⁷Be levels were also measured in soil covered by each type of plant as well as in the nearest uncovered soil to be reference values to determine its intercepted amount and consequently PM_2.5. The lowest interception, 17.7?%, was by Ficus elastica L., while Ficus retusa L. intercepted about 45?%. Radiologically, the annual effective dose due to the usage of Thymelea hirsute plant leaves as a medicine and Nicotiana glauca Graham for smoking were 0.013 and 0.66 µSv, respectively. The observed levels in rainwater indicated that ⁷Be decreased consecutively from 3.1 Bq kg^–1 in the first rain to 0.71 Bq kg^–1 in the last one during the 2016/2017 rain season. The wet deposition of ⁷Be is less than 1?% of its total deposition on the ground.