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The present study deals with fabricating and characterizing glass fiber reinforced epoxy composites with heavy mineral filler (magnetite particles) for potential low-energy radiation shielding applications. The composite materials were fabricated by the hand layup method. Glass/epoxy composite was used as control sample, and radiation shielding composites were manufactured by mixing 20 and 30% (by weight) magnetite particles with epoxy resin. It was revealed that the tensile properties of the magnetite-modified composites were increased, and the composites containing 30% filler exhibited maximum improvement than the control ones. Further assessment of the composite samples was performed by DMA (Dynamic Mechanical Analysis), TGA (Thermogravimetric Analysis), FTIR (Fourier-Transform Infrared) spectroscopy, water uptake (%), and SEM (Scanning Electron Microscopy) testing. The radiation shielding ability of the control and filler-modified composites was assessed by using a gamma (γ) radiation source (60Co). Then, the shielding efficiency was characterized by radiation-reduced intensity (%), LAC (Linear Attenuation Coefficient), MAC (Mass Attenuation Coefficient), HVL (Half Value Layer), TVL (Tenth Value Layer), and SVL (Sixteenth Value Layer). It was revealed that the 30% magnetite filler content composite experienced relatively good attenuation performance against γ-ray than other studied composites. [ABSTRACT FROM AUTHOR]

Radon (222Rn), an inert gas, is considered a silent killer due to its carcinogenic characteristics. Dhaka city is situated on the banks of the Buriganga River, which is regarded as the lifeline of Dhaka city because it serves as a significant source of the city's water supply for domestic and industrial purposes. Thirty water samples (10 tap water from Dhaka city and 20 surface samples from the Buriganga River) were collected and analyzed using a RAD H2O accessory for 222Rn concentration. The average 222Rn concentration in tap and river water was 1.54 ± 0.38 Bq/L and 0.68 ± 0.29 Bq/L, respectively. All the values were found below the maximum contamination limit (MCL) of 11.1 Bq/L set by the USEPA, the WHO-recommended safe limit of 100 Bq/L, and the UNSCEAR suggested range of 4–40 Bq/L. The mean values of the total annual effective doses due to inhalation and ingestion were calculated to be 9.77 μSv/y and 4.29 μSv/y for tap water and river water, respectively. Although all these values were well below the permissible limit of 100 μSv/y proposed by WHO, they cannot be neglected because of the hazardous nature of 222Rn, especially considering their entry to the human body via inhalation and ingestion pathways. The obtained data may serve as a reference for future 222Rn-related works. [ABSTRACT FROM AUTHOR]

The objective of the study was to investigate the effects of feeding different doses of phytobiotics on growth performance, breast meat quality, blood biochemical profiles, and liver enzymes of broiler chickens. A total of 480 one-day-old Cobb 500 chicks were randomly assigned to four feeding treatments with six replicates. Phytobiotics (natural extracts of Macleaya cordata plant) were administered at the following doses: no phytobiotics (control); phytobiotics at the rate of 0.15 g/kg; phytobiotics at the rate of 0.20 g/kg; and phytobiotics at the rate of 0.25 g/kg feed. A similar managemental practise was followed and corn-soya based mash diet was fed in two phases: starter (0 --14 days) and grower (15--28 days). Data were subjected to one-way analysis of variance (ANOVA), and polynomial analysis was used to determine the linear and quadric effects. No significant difference in growth data was observed with the addition of phytobiotics. However, breast meat yield was significantly (P = 0.02) improved by the inclusion of phytobiotics at 0.20 g/kg feed. Lightness (L*), redness (a*), and yellowness (b*) of breast meat were significantly (P = 0.01) enhanced with increasing doses of phytobiotics at 0.25 g/kg of feed. The pH of breast meat was unchanged after 0 hours, but after 24 hours, the addition of phytobiotics had significantly decreased the pH (P = 0.03). Highdensity lipoprotein (HDL) (P = 0.02) and total protein (TP) (P = 0.01) levels were maximum at 0.25 g phytobiotics/kg feed. Aspartate aminotransferase (AST) (P = 0.01) and alanine aminotransferase (ALT) levels were decreased with increasing doses of phytobiotics. All statistically significant parameters were characterized by both linear and quadratic contrasts. Overall, the data showed that breast meat yield was improved by the addition of phytobiotics at 0.20 g/kg diet, while growth performance, breast meat quality, blood biochemical profiles, and liver functions were well maintained by the addition of phytobiotics at 0.25 g/kg diet in commercial broiler chickens. [ABSTRACT FROM AUTHOR]

Thermoelectric properties of nanostructured Sb2Te3/graphite composites are investigated both experimentally and theoretically and the contribution of graphite to heat transport mechanism is addressed. XRD results indicate the solid state insolubility of the graphite phase in Sb2Te3 as no shift is observed in the diffraction peaks corresponding to Sb2Te3 in the composite samples. Raman spectroscopic analysis confirms the presence of graphite in the nanostructured composite samples. Temperature dependence of carrier concentration nH, thermal conductivity κ, Seebeck coefficient S, resistivity ρ, and, hence, the thermoelectric figure of merit ZT is reported. Graphite incorporation leads to around 40% decrease of κ, essentially due to the decrease of lattice thermal conductivity, κL. A low κL value of 0.8 Wm−1 K−1 is reported, which mostly arises due to enhanced phonon scattering at the heterointerfaces created by the addition of graphite. S increases in Sb2Te3/graphite nanocomposites. Calculation reveals that reported large S value is related with the low hole concentration. Theoretical simulation in the frame of Boltzmann equation approach shows satisfactory agreement of nH, S, and ρ with experimental data, and based on the modification of the density of states and its derivative near Fermi energy with graphite addition, a plausible explanation is provided. [ABSTRACT FROM AUTHOR]

Detailed structural and magnetic investigations have been performed on two equally Fe-doped MnCoGe alloys of nominal compositions Mn 0.875 Fe 0.125 CoGe and MnCo 0.875 Fe 0.125 Ge. The presence of martensitic phase transition (MPT) in both alloys is clear from the temperature variation of structural and magnetic properties. The nature of MPT is found to be complete in the Mn site Fe-doped alloy. On the other hand, a partial nature of the MPT is observed for the Co site Fe-doped alloy. The application of external hydrostatic pressure hardly affects the magnetic and structural transition temperatures. Both alloys show a significant amount of the magnetocaloric effect in ambient as well as in high pressure situation around their magnetic and structural transition regions. [ABSTRACT FROM AUTHOR]