Polymer composites of high-density polyethylene (HD-PE) filled with powdered lead oxide nanoparticles (PbO NPs) and bulk lead oxide (PbO Blk) were prepared with filler weight fraction 10% and 50%. ...These polymer composites were investigated for radiation-shielding of gamma-rays emitted from radioactive point sources 241Am, 133Ba, 137Cs, and 60Co. The polymer was found to decrease the heaviness of the shielding material and increase the flexibility while the metal oxide fillers acted as principle radiation attenuators in the polymer composite. The prepared composites were characterized by Fourier transform infrared spectrophotometer (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), Brunauer-Emmett-Teller surface area (BET) and field emission transmission electron microscope (FE-TEM). The morphological analysis of the assembled composites showed that, PbO NPs and PbO Blk materials exhibited homogenous dispersion in the polymer-matrix. Thermogravimetric analysis (TGA) demonstrated that the thermal-stability of HD-PE was enhanced in the presence of both PbO Blk and PbO NPs. The results declared that, the density of polymer composites was increase with the percentage of filler contents. The highest density value was identified as 1.652gcm−3 for 50wt% of PbO NPs. Linear attenuation coefficients (µ) have been estimated from the use of XCOM code and measured results. Reasonable agreement was attended between theoretical and experimental results. These composites were also found to display excellent percentage of heaviness with respect to other conventional materials.
•γ-Ray shielding characteristics of polymeric composites.•High-density polyethylene (HD-PE)-filled-powered lead oxide nanoparticles.•Good attenuating shielding for γ-ray by composites-loaded-PbO NPs.
This work investigates the γ-ray shielding characteristics of composite materials based on recycled high-density polyethylene (r-HDPE). The designed shielding materials are low-cost and sustainable ...plastic wastes with different fractions of lead oxide nanoparticles (PbO NPs) and bulk powder. The composite samples were prepared via compression molding technique and characterized by Fourier transform infrared spectrophotometer (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), field emission-transmission electron microscope (FE-TEM), Brunauer–Emmett–Teller surface area (BET), and X-ray diffraction (XRD). The γ-rays attenuation-coefficients were measured as a function of the percentage of lead oxides for several γ-ray energies using point sources 241Am, 133Ba, 137Cs, and 60Co. The experimental results show that r-HDPE with both bulk PbO and PbO NPs composites are better shielding for γ-ray than r-HDPE itself. The composites-loaded-PbO NPs were the best shielding materials for γ-ray compared to that filled with bulk PbO. The theoretical values of the linear-attenuation (μ) were extracted from the mass-attenuation coefficient (μ/ρ) and calculated using the XCOM program. The proposed composites when compared to conventional shielding materials implement as strong rivals to barite, steel and concrete particularly at higher filler wt% and for low energy γ-ray.
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•Low-cost and sustainable plastic wastes-lead oxide nanoparticles.•Recycled high-density polyethylene (r-HDPE) plastics.•The waste composites were characterized by different techniques.•Shielding characteristics of waste nanocomposites for γ-ray radiation.•Excellent shielding of γ-ray using waste composites-loaded-PbO NPs.
Most dye stuffs and coloring materials are mainly categorized as hazardous pollutants in water effluents due to their nature as non-biodegradable, highly toxic and extremely carcinogenic. For this ...reason, rapid and efficient eradication of waste dyes from wastewaters before discharging into water streams must be accomplished by an acceptable approach as adsorption technique. Therefore, the present study is aimed and devoted to synthesize a novel nanobiosorbent from three different constituents, gelatin (Gel) as a sustainable natural product, graphene oxide (GO) as an example of highly stable carbonaceous material and zirconium silicate (ZrSiO
) as an example of combined metal oxides for the formation of Gel@GO-F-ZrSiO
@Gel by using formaldehyde (F) as a cross-linkage reagent. Several characterization techniques as FT-IR were employed to identify the incorporated surface reactive Functionalities in Gel@GO-F-ZrSiO
@Gel as -OH, =NH, -NH
, -COOH and C=O, etc. The morphology for particle shape and size of Gel@GO-F-ZrSiO
@Gel were confirmed from the SEM and TEM analyses providing 15.75- 32.79 nm. The surface area was determined by the BET and found to correspond to 219.46 m
g
. Biosorptive removal of basic fuchsin (BF) pollutant as an example of a widely applicable dye in various activities was monitored and optimized under the influence of pH (2-10), reaction time (1-30 min), initial BF pollutant concentration (5-100 mg L
), nanobiosorbent dosage (5-60 mg), temperature (30-60 °C) and interfering ions. The maximum biosorptive removal values of BF dye were established as 96.0 and 95.2% using 5 and 10 mg L
, respectively at the recommended pH 7 condition. The Thermodynamic parameters demonstrated that the BF dye adsorption onto Gel@GO-F-ZrSiO
@Gel was taken place via spontaneous and endothermic reaction. Chemisorption is the predominant adsorption mechanism by forming multilayers upon nonhomogeneous surface in accordance with Freundlich model hypothesis. The applicability of the optimized Gel@GO-F-ZrSiO
@Gel in biosorptive removal of BF pollutant from real water sample was successfully accomplished by the batch technique. Thus, this study clearly shows that Gel@GO-F-ZrSiO
@Gel exhibited significant influences on remediation of industrial effluents containing BF pollutant with superior efficiency.
Spinel cobalt ferrite/hexagonal strontium hexaferrite (2CoFe2O4/SrFe12−2xSmxLaxO19; x = 0.2, 0.5, 1.0, 1.5) nanocomposites were fabricated using the tartaric acid precursor pathway, and the effects ...of La3+–Sm3+ double substitution on the formation, structure, and magnetic properties of CoFe2O4/SrFe12−2xSmxLaxO19 nanocomposite at different annealing temperatures were assayed through X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. A pure 2CoFe2O4/SrFe12O19 nanocomposite was obtained from the tartrate precursor complex annealed at 1100 °C for 2 h. The substitution of Fe3+ ion by Sm3–+La3+ions promoted the formation of pure 2CoFe2O4/SrFe12O19 nanocomposite at 1100 °C. The positions and intensities of the strongest peaks of hexagonal ferrite changed after Sm3+–La3+ substitution at ≤1100 °C. In addition, samples with an Sm3+–La3+ ratio of ≥1.0 annealed at 1200 °C for 2 h showed diffraction peaks for lanthanum cobalt oxide (La3Co3O8; dominant phase) and samarium ferrite (SmFeO3). The crystallite size range at all constituent phases was in the nanocrystalline range, from 39.4 nm to 122.4 nm. The average crystallite size of SrFe12O19 phase increased with the number of Sm3+–La3+ substitutions, whereas that of CoFe2O4 phase decreased with an x of up to 0.5. La–Sm co-doped ion substitution increased the saturation magnetization (Ms) value and the subrogated ratio to 0.2, and the Ms value decreased with the increasing number of double substitutions. A high saturation magnetization value (Ms = 69.6 emu/g) was obtained using a La3+–Sm3+ co-doped ratio of 0.2 at 1200 for 2 h, and a high coercive force value (Hc = 1192.0 Oe) was acquired using the same ratio at 1000 °C.
(1) Background: Children spend a lot of time within schools. The school setting generally has many ergonomic hazards and reinforced behavior patterns which put children at greater risk of ...environmental hazards than adults during their critical developmental stages. (2) Objective: The aim of the current study was to investigate the prevalence of musculoskeletal disorders (MSDs) and detect spinal deformities amongst general and technical secondary school students. (3) Methods: A total of 418 students from the second grade of secondary school in Shaquira governorate, Egypt participated in this cross-sectional study. Each student in the study was screened via Nordic Musculoskeletal Questionnaire (NMQ) and had their upper limb posture measured via RULA (Rapid Upper Limb assessment), and the deviation in their thoracic curve was measured using a scoliometer. (4) Results: There was a prevalence of MSDs amongst students as there were 69.7% of general school students and 83.8% of the technical school students suffering from MSDs with a statistically significant difference between both technical and general school students in RULA score and musculoskeletal complaints, whereas there were non-statistical differences in the scoliometer scale in both general and technical education students. (5) Conclusions: Musculoskeletal problems are prevalent among Egyptian secondary school students, with higher prevalence between technical school students. Therefore, preventive measures and strategies are recommended to overcome the future complications of these musculoskeletal disorders.
Abstract
The paper discusses how to evaluate the reliability of units produced by different production lines. The procedure is based on selecting independent random samples of units produced by ...different production lines and then evaluating reliability functions for each group of units. The comparison between these reliability functions at a given time allows manufacturing experts to evaluate the effectiveness of production lines. A statistical methodology has been taken based on the assumption that the lifetime of units produced by each product line has a Weibull Gamma distribution. Then, real‐world data are used to illustrate the study's contribution to reliability theory applications.
The current study was conducted to investigate the possible ameliorative role of zinc nanoparticles (Zn NPs) against silver nanoparticles (Ag NPs)-induced oxidative and apoptotic brain damage in ...adult male rats. Twenty-four mature Wistar rats were randomly and equally divided into four groups: control group, Ag NPs group, Zn NPs group, and Ag NPs + Zn NPs group. Rats were exposed to Ag NPs (50 mg/kg) and/or Zn NPs (30 mg/kg) daily by oral gavage for 12 weeks. The results revealed that exposure to Ag NPs significantly increased malondialdehyde (MDA) content, decreased catalase and reduced glutathione (GSH) activities, downregulated the relative mRNA expression of antioxidant-related genes (Nrf-2 and SOD), and upregulated the relative mRNA expression of apoptosis-related genes (Bax, caspase 3 and caspase 9) in the brain tissue. Furthermore, severe neuropathological lesions with a substantial increase in the caspase 3 and glial fibrillary acidic protein (GFAP) immunoreactivity were observed in the cerebrum and cerebellum of Ag NPs-exposed rats. Conversely, co-administration of Zn NPs with Ag NPs significantly ameliorated most of these neurotoxic effects. Collectively, Zn NPs can be used as a potent prophylactic agent against Ag NPs-induced oxidative and apoptotic neural damage.
•Silver nanoparticles (Ag NPs) induce oxidative stress in the nervous tissue of rats.•Ag NPs increase the expression of apoptosis-related genes in the brain of rats.•Ag NPs increase caspase 3 and GFAP immunoreactivity in rats’ brain.•Zinc nanoparticles (Zn NPs) have antioxidant and antiapoptotic effects.•Zn NPs ameliorate Ag NPs-induced neurotoxic effects in rats.
In this article, based on progressively type-II censored schemes, the maximum likelihood, Bayes, and two parametric bootstrap methods are used for estimating the unknown parameters of the Weibull ...Fréchet distribution and some lifetime indices as reliability and hazard rate functions. Moreover, approximate confidence intervals and asymptotic variance-covariance matrix have been obtained. Markov chain Monte Carlo technique based on Gibbs sampler within Metropolis–Hasting algorithm is used to generate samples from the posterior density functions. Furthermore, Bayesian estimate is computed under both balanced square error loss and balanced linear exponential loss functions. Simulation results have been implemented to obtain the accuracy of the estimators. Finally, application on the survival times in years of a group of patients given chemotherapy and radiation treatment is presented for illustrating all the inferential procedures developed here.
Accelerated life testing is very important in life testing experiments because it saves time and cost. In this paper, assuming that the lifetime of items under use condition follows the modified ...Weilbull distribution, partially accelerated life tests based on progressive Type-II censored samples are considered. The likelihood equations are to be solved numerically to obtain the maximum likelihood estimates. Based on normal approximation to the asymptotic distribution of maximum likelihood estimates, the approximate confidence intervals for the parameters are derived. Two bootstrap confidence intervals called bootstrap-p and bootstrap-t are also discussed. It is difficult to get explicit form for Bayes estimates, so we use Markov chain Monte Carlo method to solve this problem, which gives us flexibility to construct the credible intervals for parameters. Finally, a simulation study is performed to compare between MLEs and Bayes estimates.
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