The fabrication of reliable and cost‐effective gas sensor for low concentrations of toxic gases such as ammonia is still a challenging task, in this work the authors report structural, topography, and optical properties of pure and Ba‐doped Mn3O4 thin films prepared by chemical spray pyrolysis (CSP) as well as its gas sensing performance toward low concentrations of ammonia gas. XRD analyses prove the films have tetragonal spinel structure with a preferred orientation along the direction (103). AFM and SEM measurements show the films have homogeneous with rough surfaces and porous structures. EDS measurement confirms the presence of Mn, O, and Ba elements according to a doping concentration ratio. Optical measurements show the optical band gap redshifts and the bond length expands as Ba concentration increases. The optimal results are achieved in Mn3O4:Ba1% thin films where porous structure, rough surface, high crystallinity, and maximum response toward (20, 30, 40, and 50 ppm) of ammonia gas with great stability. Empirical equations are suggested to evaluate the sensitivity in terms of relative bond length and RMS roughness. These results show the films are good candidates in p‐type MOS gas sensors.
Pulsed laser deposition (PLD) was used to create thin copper-doped cadmium oxide (CdO) films at various concentrations. The deposition process was done at room temperature (300 K). The surface morphology of the CdO thin films revealed an intricate network resembling a prism. The cubic crystal nanostructure and the CdO thin films are aligned in a (1 1 1) plane. At an operating temperature of 280 degrees Celsius, the sensing characteristics of CdO thin films with a carbon dioxide (CO) nanonanostructure were investigated. The results showed that increasing the copper concentration or increasing the gas concentration to 200 ppm would increase the sensitivity of the gas.
In this paper, the measurement of specific activity concentrations of five commercial oil samples obtained from different countries (Kuwait, U.A.E., Iran, and Germany) were carried out using (HPGe) detector. From the measurement it was observed that average values of specific activity concentrations for 238 U, 232 Th and 40 K were equal to (20.2061.4 Bq/l), (20.0803.5 Bq/l) and (162.12049.2Bq/l), respectively. The results were less than their corresponding recommended global values reported by (UNSCEAR, 1994) publication. The radiation hazard indices [I ɣ , H in , H ex , Ra eq , D Ɣ , (AEDE) in and(AEDE) out ] were also studied, and all the obtained results and their average value were also observed to be lower than their corresponding average values given by (UNSCEAR,1994(UNSCEAR, , 2000. Finally, the excess life time cancer risk (outdoor), (ELCR), results were found to be ranged from 0.10210 3 (Al-Khaleej) (Kuwaiti origin) sample to 0.14710 3 (Vulcan 330) (Iranian origin) sample, with an average value of (0.1210.012)10 3 , which were less than the world average value. Thus, the results of the present work have shown that, all the studied samples of motor oil are safe when used.
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