Structural Rietveld refinement and magnetic features of prosademium (Pr) doped Cu nanocrystalline spinel ferrites

Pr doped spinel nanoferrites having following composition Cu Pr_x Fe_2-xO₄ (x?=?0, 0.25, 0.50, 0.75, 1.00) were synthesized using sol-gel route. Prosademium (Pr) which is a rare earth metal was doped to tailor the properties of the Cu spinel nanoferrites. Characterization tools such as FTIR, XRD, FESEM and VSM were employed to investigate the phase, absorption bands, structure, microstructure and magnetic properties. FTIR was used to see the absorption bands and force constants of the Pr doped Cu spinel nanoferrites. Crystallite size, lattice parameters, cell volume and micro strains were determined from XRD data. Bulk density, X-ray density and porosity of the Pr doped Cu spinel nanoferrites were also calculated. Rietveld refinement was applied to investigate the detailed structural parameters of the Pr doped Cu spinel nanoferrites. Unit cell software based on regression diagnostics was also used to determine the structural factors of the prepared nanoferrites. It was noticed that Cu nanoferrite showed the single-phase cubic structure whereas the Pr doped Cu ferrite depicted the orthorhombic structure respectively. FESEM show large amount of agglomerations at x?=?0.00 whereas irregular shape of the particles confirms the nanosized of ferrites as well. Magnetic properties were determined from VSM which elaborated the remanence, coercivity, saturation magnetization, anisotropy constant (K), initial permeability, Bohr magneton and YK (Yafet and Kittel) angles. Magnetic saturation, coercivity, remanence and anisotropy constant were decreased with Pr concentration in Cu spinel ferrite. However, YK angles were increased with Pr doping in Cu spinel nanoferrites. Microwave frequency response was evaluated which confirm the use of these Pr doped Cu spinel nanoferrites in the range of 5.2?Ghz–9.5?GHz respectively. The properties of these Pr doped Cu spinel nanoferrites suggested their used for microwave devices, memory devices and recording media applications.     

Effect of reinforcing technique on strain-dependent dynamic properties of reinforced earth walls

Due to lack of sufficient understanding of the strain-dependent dynamic properties of reinforced mass, existing soil and reinforcement models are not capable of accurately representing the seismic response of reinforced soil structures in numerical and analytical analyses. In the present study, to evaluate the effect of reinforcing technique on strain-dependent dynamic properties of reinforced earth walls, the values of equivalent shear modulus (G_e) and damping ratio (D) were estimated for soil-nailed wall (SNW) and steel-strip reinforced-soil wall (SSW) as a function of shear strain level using 1-g shaking table tests. The results obtained showed that the variation trend of G_e and D versus γ is strongly influenced by the type of reinforcing technique and confining pressure, so that the variation trend of these two parameters versus shear strain can be well expressed as an exponential equation with a high correlation coefficient for each type of reinforced earth wall.     

Heavy metals concentrations in dairy cow feedstuffs from the south of Iran

ABSTRACT

Levels of lead, cadmium, mercury, copper and zinc elements in feedstuffs were measured by inductively coupled plasma-optical emission spectrometry. A total of 216 feedstuffs samples including corn silage, alfalfa hay, wheat straw, full ration pellet, wheat bran and barley were collected from polluted and unpolluted regions during four seasons and prepared with wet digestion. Lead and mercury concentrations did not differ significantly in various feedstuffs, but cadmium level was significantly the highest in barley samples (p < 0.05). All feed material samples had lead, cadmium and mercury concentrations well below the maximum levels allowed by the European Union. The lowest and highest levels of both copper and zinc were found in wheat straw and wheat bran, respectively, but their maximum content did not exceed the legal limits. In contrast to the sampling area, season significantly (P < 0.05) affected heavy metal levels, except for zinc, in feedstuffs.     

A correlation between morphology and mechanical performance of injected-molded PE/EVA/clay nanocomposites: Insight into phase miscibility and interfacial phenomena

In this study, the correlations between the mechanical performance and structural properties of injected-molded polyethylene (PE)/ethylene-vinyl acetate copolymer (EVA)/nanoclay (NC) nanocomposites are investigated by revisiting the interfacial phenomena and miscibility state of the component pairs. The effects of different parameters including the injection molding temperature, mixing sequence in melt-compounding process, blend composition, and nanoclay loading are studied. A great complexity arises in the filling and cooling process of the injected-molded parts owing to the phase behavior of the polyolefin blend, crystallization, and morphological changes. The injection molding temperature positively influences the elastic modulus, tensile strength and impact strength of PE/EVA/NC systems through the improvements in the PE/EVA partial miscibility, mutual solubility, and interfacial interactions of PE/clay and PE/EVA pairs. By applying a two-step mixing process before the injection molding, more nanoclay stacks with smaller thicknesses and larger clay interlayer spacing are formed. The stronger pinning effect of nanoparticles in the second mixing sequence retards the phase separation phenomenon of PE/EVA blend during the cooling stage. As a result of improved mutual PE/EVA solubility, the elastic modulus and tensile strength decrease and the impact resistance increases in the PE-rich systems. On the other hand, an opposite trend for these properties is found for the EVA-rich systems.     

Preparation and characterization of poly(vinylidene fluoride)-13X zeolite mixed matrix membranes for lithium ion batteries' separator with enhanced performance

13X zeolite was hydrothermally synthesized and poly(vinylidene fluoride) (PVDF)/13X zeolite particles mixed matrix membranes were prepared using phase inversion method as the lithium-ion battery separator. Hydrophilic and porous 13X zeolite loading impacts on the critical separator properties of morphology, wettability, electrolyte uptake, and high temperatures dimensional stability were investigated using scanning electron microscopy, contact angle, and thermal shrinkage analysis. Electrolyte uptake of the 13X zeolite particles loaded PVDF separators increased and also the incorporation facilitated the lithium ions migration (ion conductivity) due to the Lewis acidity of their structure. The 8 wt% 13X zeolite loaded separator (S2) revealed higher porosity (~+20%), electrolyte uptake (+80%), ion conductivity (+80%), and thermal shrinkage (~−47% at 165°C). C-rate capability and cycle performance of a cell battery assembled using the S2 separator considerably improved compared with those of the assembled by the neat PVDF and commercial polypropylene separators.     

Histomicroscopy and normal anatomy of the adult killifish Aphanius hormuzensis (Teleostei; Aphaniidae) from the Persian Gulf coastal environment

The histomicroscopy and normal anatomy of the major body organ systems were investigated in the adult killifish, Aphanius hormuzensis using histological examination, X‐ray imaging, double staining, light microscopy and scanning electron microscopy (SEM). Based on the histomicroscopic observations, the kidney, liver and swim bladder in the studied species were comparable to other fish models. The anterior portion of the kidney is bulbous, while the posterior portion is narrow and elongated; the liver has a single lobe and the swim bladder is a single‐chambered organ with no connection to the digestive tract (physoclistous). X‐ray imaging and double staining examination showed 12 abdominal and 15 caudal vertebrae and a single hypural plate in the caudal skeleton. According to light microscopy, the scales were rounded to pentagonal in shape with three types of radii (primary, secondary and tertiary), and the urohyal bone was elongated. SEM microscopy showed a single row of tricuspid teeth on the upper and lower jaw, respectively, each tooth has two lateral cusps that are shorter than the middle one. The number of teeth was 17–18 in the upper jaw and 19–20 in the lower jaw. The saccular otoliths were rounded‐trapezoid in shape with a moderately incised and V‐shaped excisura. The members of killifishes are an important group for biologists because of their evolutionary properties, regeneration capacity and usefulness as biological control and also for the ecotoxicological assessment of environmental pollution. The outcomes of this study may provide a useful basis for future research on the genus Aphanius.     

Effects of Dy on structural,dielectric and magnetic properties of Ni-Sr-Y co-precipitated hexaferrites

Dysprosium (Dy) doped Y-type strontium hexa ferrites of the following composition Ni₂Sr₂Dy_xFe_12-xO₂₂ where (x?=?0.00, 0.05, 0.10, 0.15, 0.20, 0.25) were prepared through co-precipitation process. Phase analysis of the investigated samples was carried out by characterizing through (XRD) X-ray diffraction which confirmed the pure phase of Y-type hexaferrites. Dysprosium ion doping influenced lattice parameters i.e. lattice constants (a, c), crystallite size, (c/a) ratio, cell volume and porosity. The calculated crystallite size was in the range of 88–159?nm. FTIR plots showed that the characteristics bonds of Ni₂Sr₂Dy_xFe_12-xO₂₂ are appreciably influenced by the incorporation of Dy contents. The results of dielectric parameters revealed that dielectric constant, dielectric loss, tanloss were decreased with an increase in frequency. At 6.0?×?10⁸ Hz, dielectric constant decreased from 5.55 to 3.69 with increasing Dy concentration. Owing to Maxwell-wagner type relaxation, the decrease in dielectric constant was noticed at higher frequency. The smaller dielectric constants and dielectric losses make these materials suitable for their applications in microwave devices fabrication.