Analyses of silicon dioxide, magnesium oxide, lead fluoride, bismuth as low-pass velocity filters for neutrons

Transmission measurement of neutrons by filter materials for low energy neutrons is important for the study of structure and dynamics of condensed matter. Since only thermal neutrons are useful for such experiments, filter materials that transmit thermal neutrons while attenuating fast neutrons and gamma rays are of considerable interest

Reducing Mud Using Highway-Type Filter Materials

Several beef and dairy producers across the country have been successful in dramatically reducing mud problems without resorting to the use of expensive concrete or pavement. A load-bearing material used in the highway industry can be placed in high animal traffic areas, on mounds, around feed bunks and in transition areas where animals move onto or off of concrete. The materials are of two basic types; 1) geotextiles, which are a porous filter-type material, and 2) polyethelye-type plastic grid material. Costs for installing the finished surface are about one-third the cost of concrete

A first-principles DFT+GW study of spin-filter and spin-gapless semiconducting Heusler compounds

Among Heusler compounds, the ones being magnetic semiconductors (also known as spin-filter materials) are widely studied as they offer novel functionalities in spintronic/magnetoelectronic devices. The spin-gapless semiconductors are a special case. They possess a zero or almost-zero energy gap in one of the two spin channels. We employ the $GW$ approximation, which allows an elaborate treatment of the electronic correlations, to simulate the electronic band structure of these materials. Our results suggest that in most cases the use of $GW$ self energy instead of the usual density functionals is important to accurately determine the electronic properties of magnetic semiconductors.Comment: Final version as publishe

Epitaxial strain effects in the spinel ferrites CoFe2O4 and NiFe2O4 from first principles

The inverse spinels CoFe2O4 and NiFe2O4, which have been of particular interest over the past few years as building blocks of artificial multiferroic heterostructures and as possible spin-filter materials, are investigated by means of density functional theory calculations. We address the effect of epitaxial strain on the magneto-crystalline anisotropy and show that, in agreement with experimental observations, tensile strain favors perpendicular anisotropy, whereas compressive strain favors in-plane orientation of the magnetization. Our calculated magnetostriction constants $\lambda_{100}$ of about -220 ppm for CoFe2O4 and -45 ppm for NiFe2O4 agree well with available experimental data. We analyze the effect of different cation arrangements used to represent the inverse spinel structure and show that both LSDA+U and GGA+U allow for a good quantitative description of these materials. Our results open the way for further computational investigations of spinel ferrites

Evaluating Filter Materials for E. Coli Removal from Stormwater

Stormwater runoff from agricultural and urban areas carries a wide range of pollutants and pathogens that can negatively affect surface water bodies and cause significant risks to the ecosystem and public health. Bacteria is one of the pollutants carried by stormwater, and Escherichia coli (E. coli) is commonly used as a microbial pollution indicator of surface water. The aim of this research was to investigate the removal of E. coli from stormwater using low-cost filter materials. Two industrial byproducts (steel slag and steel chips) and two natural minerals (zeolite and limestone) with three different sizes (0.5-1 mm, 1-2 mm, and 2-4 mm) were chosen to investigate the potential of these materials as filter media for E. coli removal from stormwater. Batch experiments were conducted to investigate the impact of initial E. coli concentration, temperature, pH, particles size and mass, salt, natural organic matter (NOM), and contact time on the removal of E. coli. Column adsorption experiments were also performed to obtain the E. coli adsorption characteristics of steel chips, steel slag, limestone, and zeolite under continuous flow conditions. In addition, the E. coli release potential of these materials were determined. Using a desorption test, the batch adsorption results demonstrated that the maximum E. coli removal efficiencies of 100%, 99.5%, 86.5%, and 80.2% were achieved using steel byproducts, steel slag, limestone, and zeolite, respectively, using E.coli concentrations of 107 MPN/mL for steel chips and 104 MPN/mL for steel slag, limestone, and zeolite, in the synthetic stormwater. Increasing pH from 5 to 9 resulted in a reduction in E. coli adsorption by 33.5% and 19.0% for steel chips and steel slag, respectively. As temperature increased steel chips and steel slag adsorption capacities increased. The effect of the addition of NOM on E. coli removal efficiencies was determined. The results indicated that E. coli removal efficiency were reduced by 19.77% and 41.77% for steel chips and 6.86% and 11.56% for steel slag in the presence of 20 and 50 mg/L of NOM. Moreover, E. coli release from steel chips was negligible in comparison with other absorbents. Finally, adding high salt concentrations in E. coli solution showed a significant impact in natural minerals adsorption capacities. As the salinity increased the E. coli adsorption capacity of limestone and zeolite were improved by 23.5%, and 35.5%, respectively

Effect of organic load on phosphorus and bacteria removal from wastewater using alkaline filter materials

AbstractThe organic matter released from septic tanks can disturb the subsequent step in on-site wastewater treatment such as the innovative filters for phosphorus removal. This study investigated the effect of organic load on phosphorus (P) and bacteria removal by reactive filter materials under real-life treatment conditions. Two long-term column experiments were conducted at very short hydraulic residence times (average ∼5.5 h), using wastewater with high (mean ∼120 mg L−1) and low (mean ∼20 mg L−1) BOD7 values. Two alkaline filter materials, the calcium-silicate material Polonite and blast furnace slag (BFS), were tested for the removal capacity of total P, total organic carbon (TOC) and Enterococci. Both experiments showed that Polonite removed P significantly (p < 0.01) better than BFS. An increase in P removal efficiency of 29.3% was observed for the Polonite filter at the lower concentration of BOD7 (p < 0.05). Polonite was also better than BFS with regard to removal of TOC, but there were no significant differences between the two filter materials with regard to removal of Enterococci. The reduction in Enterococci was greater in the experiment using wastewater with high BOD7, an effect attributable to the higher concentration of bacteria in that wastewater. Overall, the results demonstrate the importance of extensive pre-treatment of wastewater to achieve good phosphorus removal in reactive bed filters and prolonged filter life

Evaluation of the Influence of Additional Beam Filtration on Image Quality and Patient Dose in X-ray Fluoroscopy Procedures

The aim of the study was to evaluate the influence of additional filtration on radiation dose and image quality for patients during hysterosalpingography (HSG) and retrograde urethrography (RUG) procedures. The influence of filtering on image quality for each phantom thickness was made using a combination of different filter thicknesses. Entrance surface air kerma (ESAK) rates to Perspex phantom were measured using a solid state detector for various added combination of filter materials. Fluoroscopic image contrast was assessed using a Leeds TOR-18FG test object with a range of filter materials and phantom thicknesses. Phantom studies demonstrated that the use of additional filter materials of up to 0.35 mm thickness of copper could be used without significant effect on the image quality. ESAK values were determined for 16, 20, 24 and 28 cm phantom. Phantom ESAK reduced by 63%, 63%, 64% and 65% for 16, 20, 24 and 28 cm, respectively, when using 0.35 mm Cu + 1 mmAl, without degrading image contrast. Three independent radiologists perceived no change in clinical image quality with added filtration. On adding 0.35 mm Cu and 1 mm Al, the KAP per examination for the HSG was reduced by 71%, while for the RUG was reduced by 75%.Key words: Additional filtration; image quality; patient dose; X-ray fluoroscopy procedure

Water quality management in gold fish (Carassius auratus) rearing tanks using different filter materials

The present study deals with the management of water quality in Carassius auratus (gold fish) rearing tanks using different filter materials. The system with dead coral pieces (DCP) is the most suitable for rearing gold fish