Comparison of three‐dimensional analysis and stereological techniques for quantifying lithium‐ion battery electrode microstructures

Lithium‐ion battery performance is intrinsically linked to electrode microstructure. Quantitative measurement of key structural parameters of lithium‐ion battery electrode microstructures will enable optimization as well as motivate systematic numerical studies for the improvement of battery performance. With the rapid development of 3‐D imaging techniques, quantitative assessment of 3‐D microstructures from 2‐D image sections by stereological methods appears outmoded; however, in spite of the proliferation of tomographic imaging techniques, it remains significantly easier to obtain two‐dimensional (2‐D) data sets. In this study, stereological prediction and three‐dimensional (3‐D) analysis techniques for quantitative assessment of key geometric parameters for characterizing battery electrode microstructures are examined and compared. Lithium‐ion battery electrodes were imaged using synchrotron‐based X‐ray tomographic microscopy. For each electrode sample investigated, stereological analysis was performed on reconstructed 2‐D image sections generated from tomographic imaging, whereas direct 3‐D analysis was performed on reconstructed image volumes. The analysis showed that geometric parameter estimation using 2‐D image sections is bound to be associated with ambiguity and that volume‐based 3‐D characterization of nonconvex, irregular and interconnected particles can be used to more accurately quantify spatially‐dependent parameters, such as tortuosity and pore‐phase connectivity.     

A COMPARISON OF PROTEIN ASSAYS FOR THE DETERMINATION OF THE PROTEIN CONCENTRATION OF BEER

Seven protein assays have been compared for determination of the protein content of beer. Dialysis and ultrafiltration have been used to investigate possible interference and the protein content of the samples has been simultaneously monitored by sodium dodecyl sulphate-polyacrylamide gel electro-phoresis. The Fisons NA2000 Nitrogen/Protein Analyzer gave identical results to the standard Kjeldahl method but both measure nitrogen-containing compounds rather than protein. Colorimetric methods based upon the biuret reaction (including the Lowry and bicinchoninic acid protein assays) are particularly prone to interference from reducing substances and gave protein concentration values dependent upon the sample volume. The protein dye-binding assays (Coomassie Brilliant Blue and pyrogallol red-molybdate methods) were optimal for beer protein analysis displaying minimal inter ference and giving reproducible protein concentration values consistent with the protein content of the beers as indicated by electrophoresis.     

POTENTIAL FOR BACTERIAL GROWTH ON THE FRESH CUT TROPICAL SQUASH, CALABAZA (CURCUBITA MOSCHATA), DURING STORAGE

Calabaza (Curcubita moschata) is a tropical squash which is gaining popularity as a specialty crop for agricultural producers in the Northeast United States. It is commonly marketed by being cut in half, wrapped in plastic and may be held unrefrigerated until sold. This method of display is essential for consumer acceptance, yet unrefrigerated storage means that some potential for food safety problems exists. Experiments were conducted to determine the potential for bacterial growth during storage of cut calabaza. Freshly cut calabaza contained between 1.3 and 4.7 log₁₀CFU/g aerobic mesophiles. By 10 h, duplicate counts from some samples exceeded 4 log₁₀ CFU/g. After 24 h of room temperature storage, total aerobic plate counts ranged from 5.2 to 7.7 log₁₀ CFU/g. Rapid bacterial growth on cut calabaza stored at room temperature indicates that these products are highly perishable, and may be able to support the growth of pathogenic bacteria, should they be introduced during the slicing process.     

SELECTING DEFORMATION RATES IN TEXTURE TESTS *

Abstract . Since mastication involves high deformation rates (150cm min^?1), the arbitrarily selected slow deformation rates usually used in instrumental texture tests can lead to erroneous results and lack of correlation with sensory evaluation with respect to the order of sample ranking. Sophisticated instrumentation that is costly to operate is required to accurately simulate the deformation rates operating in the mouth. It is suggested that instrumental data obtained at slow rates could be evaluated in a more meaningful manner if series of similar samples were tested at increasing deformation rates and the plotted force/deformation curves extrapolated to 150cm min^?1. It is implied that recording systems would be more useful, if in addition to force, they sensed the rate of force change with deformation rate.     

Effects of Frozen Storage and Cooking on Lipid Oxidation in Chicken Meat

Fresh chicken breast and leg meat samples, which were frozen for 3 months or 6 months at −18°C, were cooked in microwave and convection ovens and then tested for levels of lipid oxidation. After 6 months storage, malonaldehyde in fat from meat samples, as measured by a TBA assay, modified to avoid sample autoxidation, increased 2.5 fold, while the fluorescence excitation (360 nm) and emission (440 nm) spectra increased an average of 34%. Fat from meat cooked in a convection oven averaged 83% higher malonaldehyde concentration and 21% higher fluorescence compared to levels before cooking. Levels of lipid oxidation products in fat from chicken breast and leg meat were not significantly different in microwave compared to convection oven cooking; but certain secondary fluorescent products were higher in meats cooked by convection oven.     

MEASUREMENT OF PEA TENDERNESS IV. Development and Evaluation of the Test Cell*

A wire extrusion cell was developed to measure pea tenderness. The area of the cell and the wire grid dimensions affected the readings. The maximum force was linearly related to the total length of the shearing wires and the open area of the grid. Cells could be made interchangeable in testing unsieved peas within 1% or better using economic manufacturing tolerances. Sample temperature, time after harvest and damage to the wires of the test cell had negligible effects on the readings. The effect of variation in compression speed was small and erratic. Sample weight, however, had a marked effect on the results.     

High-Temperature Hemispherical Spectral Emittance of Uranium Oxides at 0.65 and 0.70 μm

Hemispherical spectral emittances were measured for uranium oxides. The compositions ranged from UO_1.05 to UO_2,20 the bulk densities from about 8 to more than 10.6 g/cm³, the apparent porosities from less than 0.5 to 19.0%, and the temperatures from about 450° to about 2400°K. The data were taken at wavelengths of 0.656 and 0.70 μm. The emittance is high in all cases (from about 0.70 to above 0.90) and increases with increasing wavelength. The emittance is not strongly sensitive to temperature, porosity, density, surface finish, or stoichiometry. The high emittance values are linked to the absorption edge observed for uranium oxides in the visible portion of the spectrum.     

THE COGNITIVE EFFECTS OF SENSORY DEPRIVATION: THE ROLE OF TASK COMPLEXITY.

TESTED 40 MALE UNDERGRADUATES UNDER 4 DRIVE CONDITIONS WITH 2 LEVELS OF TASK COMPLEXITY. IT WAS FOUND THAT TASK COMPLEXITY AND DRIVE AROUSAL INTERACTED TO LEAD TO DIFFERENTIAL PERFORMANCE ON COGNITIVE TASKS. ON A COMPLEX TASK, BOTH MODERATE AND HIGH DRIVE LED TO DECREMENTS; ON A SIMPLE TASK, MODERATE DRIVE RESULTED IN IMPROVEMENT WHICH LEVELED OFF UNDER HIGH DRIVE. THE DRIVE OPERATIONS, VARIED INDEPENDENTLY, WERE SENSORY DEPRIVATION AND FINANCIAL INCENTIVE. THE DATA HELP TO CLARIFY THE INCONSISTENT LITERATURE RELATING SENSORY DEPRIVATION TO COGNITIVE PERFORMANCE. (FRENCH SUMMARY) (17 REF.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Heuristic improvement through triangulation

Abstract

This paper presents a method for improving heuristics using a triangulation technique. Instead of using a heuristic to directly estimate distance (X₁, X₂) between nodes X₁ and X₂, the proposed technique selects a reference node R_i applies the heuristic to (X₁,R_i) and (X₂,R_i), and uses the Euclidean distance formula to calculate a new heuristic value. If two nodes are close to each other, then they should also be approximately equidistant to a third reference node. Utilizing a set of many such reference nodes, node expansions can be reduced for a large class of heuristics. Very early results for this method, referred to as multi-dimensional heuristics, showed that fewer node expansions were needed when using the triangulation technique. New results in this paper include the development of a new learning procedure for selecting reference nodes, experimentation on reusing reference node sets for multiple goal instances, a comparison of multi-dimensional heuristics with weighting and how they dynamically weight states near the goal, and some observations which help explain how and why this technique improves heuristics.     

MEASUREMENT OF PEA TENDERNESS

Abstract Twenty one tenderometers were compared in processing plants for their accuracy of measurement using wax wafers as the test material. The results indicate that there are serious differences among the tenderometers and that the accuracy of measurement is unsatisfactory for the purpose of grading peas to establish the price paid to the grower. If a relationship of compatible trust is to remain between the processor and the grower, serious consideration must be given either to better calibration of currently used tenderometers or to devising some other method of grading and paying for peas.