Experimental Study on the Corrosion of Carbon Steel and Aluminum Alloy in Firefighting Protein Foam Concentrates

The corrosion of mild steel and Al alloy in Fomtec P 6% and 6% P Profoam 806 protein-based foam concentrates was investigated. Weight-loss data for steel showed corrosion penetration of 0.745 mipy in Fomtec and 2.269 mipy in Profoam, whereas for Al alloy the penetration levels were 0.474 and 1.093 mipy, respectively. Scanning electron microscopy and energy dispersive X-ray spectroscopy allowed characterization of the metallic surface covered or free from corrosion products. Values of corrosion potential, corrosion current density and corrosion penetration were calculated by using potentiodynamic polarization curves. Electrochemical impedance spectra illustrated the change in polarization resistance during anodic polarization. Data obtained by accelerated electrochemical methods confirm the greater aggressiveness of the Profoam concentrate compared to Fomtec concentrate.

Nucleon-nucleus velocity-dependent optical model: Revisited

In this work we study nucleon-nucleus elastic scattering using a nonlocal, velocity-dependent optical potential. The potential parameters are determined by fitting elastic angular distributions and polarization data for nucleon scattering off a wide range of nuclei falling in the mass range $12 \leq A \leq 208$ and over the energy range 10 - 60 MeV. Our potential parameters lead to smoothly varying local equivalent potentials and, unlike previous works, the potential depths corresponding to the real volume, imaginary surface, and imaginary volume terms show systematic linear dependences on energy. In addition, for each nuclear target, we determined constant sets of geometric parameters. Including the polarization data in the fitting procedure helped in reducing the large variations in the depths of the spin-orbit term. Our best-fit angular distributions and polarization data are in very good agreement with measured data, and are either as good as the cross sections obtained with widely-used systematics or better.

Limits on Polarized Dust Spectral Index Variations for CMB Foreground Analysis

Using Planck polarization data, we search for and constrain spatial variations of the polarized dust foreground for cosmic microwave background (CMB) observations, specifically in its spectral index, β d . Failure to account for such variations will cause errors in the foreground cleaning that propagate into errors on cosmological parameter recovery from the cleaned CMB map. It is unclear how robust prior studies of the Planck data that constrained β d variations are due to challenges with noise modeling, residual systematics, and priors. To clarify constraints on β d and its variation, we employ two pixel space analyses of the polarized dust foreground at >3.°7 scales on ≈60% of the sky at high Galactic latitudes. A template fitting method, which measures β d over three regions of ≈20% of the sky, does not find significant deviations from a uniform β d = 1.55, consistent with prior Planck determinations. An additional analysis in these regions, based on multifrequency fits to a dust and CMB model per pixel, puts limits on σ β d , the Gaussian spatial variation in β d . The data support σ β d up to 0.45 at the highest latitudes, 0.30 at midlatitudes, and 0.15 at low latitudes. We also demonstrate that care must be taken when interpreting the current Planck constraints, β d maps, and noise simulations. Due to residual systematics and low dust signal-to-noise ratios at high latitudes, forecasts for ongoing and future missions should include the possibility of large values of σ β d as estimated in this paper, based on current polarization data.

In situ measurements of reef squid polarization patterns using two-dimensional polarization data mapped onto three-dimensional tessellated surfaces

Reef squids belong to a group reputed for polarization sensitivity, yet polarization patterns of reef squid have not been quantified in situ . To quantify polarization patterns from video polarimetric data, we developed a protocol to map two-dimensional polarization data onto squid-shaped three-dimensional tessellated surfaces. This protocol provided a robust data container used to investigate three-dimensional regions-of-interest, producing data lineouts derived from the squid's geometry. This protocol also extracted polarimeter and squid body orientations and the solar heading from polarization images. When averaged over the solar heading, the ventral midline gave a low degree of polarization (2.4 ± 5.3%), and the area between the ventral and flank midlines had higher values (9.0 ± 5.3%). These averaged data had a large discontinuity in the angle of polarization (AoP) at the mantle's ventral midline (64 ± 55°), with larger discontinuities measured on individual squid. Ray-tracing calculations demonstrated that the AoP pattern was not related to the squid's surface-normal geometry. However, the AoP followed virtual striation axes on the squid's surface oriented 24° to the squid's long axis, similar in angle (27°) to the striations of birefringent collagen fibres documented in other squid species’ skin.

OAT EXTRACT AS A NATURAL CORROSION INHIBITOR FOR MILD STEEL IN 3% NaCl SOLUTION

In this work, we have tested a new inhibitor formulation that is effective, economically efficient and in accordance with environmental legislation. The inhibitor tested is the crude extract of the oat plant (denoted as OE) obtained by the reflux method in the water. This extract is then used as a corrosion inhibitor of mild steel in 3% NaCl. This study was carried out by using electrochemical polarizations, Electrochemical Impedance Spectroscopy and gravimetric techniques. The results obtained showed that this extract satisfactorily inhibits the dissolution rate of mild steel. The inhibition efficiency increases with inhibitor concentration and reaches 72% at 5[Formula: see text]g[Formula: see text][Formula: see text][Formula: see text]L[Formula: see text] of oat extract. Polarization data indicate that the extract acted as mixed type. The adsorption of the inhibitor on the mild steel surface in 3% NaCl follows the Langmuir adsorption isotherm. SEM analysis of the electrode surface condition confirms the results obtained.