Crack determination from boundary measurements—Reconstruction using experimental data

In this work we assess the effectiveness of Electrical Impedance Tomography for determining the presence and the location of an interior crack from boundary measurements. Electrical Impedance Tomography uses boundary voltages and currents to image the interior of a region. We collect the data needed for this nondestructive evaluation technique by laboratory experiments and apply two numerical inversion algorithms to the data. Our experiments show that the data collected are sufficient to give good estimates of crack locations and crack sizes.     

Spectroelectrochemical sensing based on multimode selectivity simultaneously achievable in a single device. 13. Detection of aqueous iron by in situ complexation with 2,2'-bipyridine

A spectroelectrochemical sensor with attenuated total reflectance at an indium-doped tin oxide (ITO) optically transparent electrode coated with a thin film of Nafion has been demonstrated for the determination of aqueous iron ion. The novelty of this sensor stems from its ability to take up colorless iron ion (Fe2+) from solution and complex it with an organic ligand, 2,2'-bipyridine (bipy), that has been previously loaded in the optically transparent charge-selective Nafion film coating the electrode. The resulting complex ion, tris(2,2'-bipyridyl)iron(II), Fe(bipy)3(2+), absorbs strongly, making it easily detectable via optical spectroscopy. Fe(bipy)3(2+) loaded into the selective film is oxidized to colorless Fe(bipy)3(3+), which gives rise to an absorbance change for quantifying iron. This paper maps the development of this sensor, from the spectroelectrochemical characterization of the complex ion at an ITO optically transparent electrode to an analysis of the uptake, retention, and optical response of the complex ion in the Nafion film. Finally, an evaluation of the uptake of aqueous Fe2+ by the bipy-loaded Nafion film is reported. These data include preliminary results illustrating the dependence of the sensor response on differing concentrations of Fe2+ in solution.     

Effect of dietary animal and vegetable protein on gallstone formation and biliary constituents in the hamster

A gallstone-inducing diet was utilized to examine the effect of dietary proteins (casein, soybean and cottonseed) on gallstone formation. Casein produced gallstones in 100% of the animals; however, soybean or cottonseed proteins reduced gallstone incidence to 32% and 0%, respectively. In an effort to ascertain the mechanisms responsible for gallstone formation, serum cholesterol and the 3 primary biliary constituents (bile acids, phospholipids and cholesterol) were measured. Casein produced a 4-fold increase in biliary cholesterol, whereas soybean and cottonseed yielded a 3-and 2-fold increase, respectively, when compared to a commercial diet (Purina, no. 5001). Serum cholesterol was reduced by substituting dietary vegetable protein for animal protein. This study suggests that substitution of vegetable for animal protein in the diet can decrease gallstone formation in hamsters. It is proposed that this reduced gallstone formation is due to the decreased concentrations of biliary cholesterol induced by dietary modification. Preliminary reports of portions of this work were presented at the XIIth International Congress of Nutrition and at the 73rd annual AOCS meeting. Liepa, G., and Mahfouz, S. (1982) J. Am. Oil Chem. Soc. 59, 316A     

Application of hybrid finite element method to electromagneticscattering from coated cylinders

A hybrid finite-element method is applied to solve the electromagnetic scattering (for both E- and H-polarizations) from coated cylinders. The coating material can be nonhomogeneous and have permeabilities and permittivities different from their free-space values. Three numerical examples are presented to show the validity and versatility of the method: (1) bistatic scattering from a coated circular cylinder which verifies the formulation and the computer program, (2) backscattering from a coated rectangular cylinder, and (3) backscattering from an ogival cylinder with coated edges. Computations are compared with those obtained using moment-method codes and exact solutions when applicable     

Studies related to the structure and reactivity of coals : 18. The chemical structures of products from reactions of a suite of higher rank Australian coals

The structure of the oils, asphaltenes and residues obtained by the thermal reactions of a suite of Australian higher rank coals under hydrogen or nitrogen have been studied by chemical and spectroscopic methods. The host-guest model that has been used to describe the structure of Australian brown coals cannot be applied directly to the higher rank coals. Evidence is provided that suggests that a modified version of the model may be of use in describing the structure of some subbituminous coals. The methodology has proved to be useful in the understanding of structural features of coals which are often not rank dependent, e.g. Callide coal (ABL2), a subbituminous coal, has been shown to have characteristics of both very high and also low rank coals.     

Effect of cell size and shape on single-cell electroporation

Single-cell electroporation was performed using electrolyte-filled capillaries on fluorescently labeled A549 cells. Cells were exposed to brief pulses (50-300 ms) at various cell-capillary tip distances. Cell viability and electroporation success were measured. In order to understand the variability in single-cell electroporation, logistic regression was used to determine whether the probabilities of cell survival and electroporation depend on experimental conditions and cell properties. Both experimental conditions and cell properties (size and shape) have a significant effect on the outcome. Finite element simulations were used to compare bulk electroporation to single-cell electroporation in terms of cell size and shape. Cells are more readily permeabilized and are more likely to survive if they are large and hemispherical as opposed to small and ellipsoidal with a high aspect ratio. The dependence of the maximum transmembrane potential across the cell membrane on cell size is much weaker than it is for bulk electroporation. Observed survival probabilities are related to the calculated fraction of the cell's surface area that is electroporated. Observed success of electroporation is related to the maximum transmembrane potential achieved.     

Modification of liquid/solid interface shape in directionally solidifying Al–Cu alloys by a transverse magnetic field

Al-0.85wt%Cu and Al-2.5wt%Cu alloys were directionally solidified under different transverse magnetic field (TMF) intensities to investigate the influence of TMF on the liquid/solid interface shape with respect to the various length scales appearing (planar, cellular, and dendritic interfaces). Results show that planar and cellular interfaces tilt to one side and then level off with increasing TMF although the dendritic interface appears not to behave in this manner. In situ synchrotron X-ray imaging was applied during directional solidification of the Al-4wt%Cu alloy under a 0.08T TMF, revealing leveling of the initially sloped interface. Solute redistribution, caused by thermoelectric magnetic convection (TEMC), responds to the changes in the interface shape. Because different typical length scales should be used in estimating the velocity of TEMC for planar, cellular, and dendritic interfaces, the maximum velocity of the convection ahead of the interface is obtained under different TMF intensities; correspondingly, leveling of the interface’s degree of slop varies with TMF.