Influence of Extrusion Cooking Conditions on the Efficiency of the Cationization and Carboxymethylation of Potato Starch Granules

A systems analytical model for the extrusion of starches and flours was modified to determine the optimal extrusion conditions for the cationization and the carboxymethylation of potato starch and to determine the effect of the extrusion conditions, optimal for the reaction yield (R.E.) and the desired degree of substitution (D.S.), on the rheological properties of the derivatives. In order to improve the describability of the postulated functional relationships between the defined system parameters and the R.E. it was decided to measure the heat flow over the length of the processing part of the extruder in order to enable a more precise measure of the specific thermal energy input (STE). Test run results showed that the STE is highly correlated to the SME. Therefore the initial proposal to substitute the STE for the product temperature in the modified systems analytical model could not be successful. The extension of the working range for these trials to higher SME and mean residence time levels compared to previous studies enabled the production of cationic starch with a maximum R.E.>90% and the production of carboxymethylstarch with a maximum R.E. of about 85%. The modified systems analytical model could not yet be used precisely for the optimization of the R.E. of the derivation of starches. The influence of process parameters and D.S. on rheological properties of the examined derivatives could be described with regression equations.     

Highly Reversible Lithiation of Additive Free T-Nb2O5 for a Quarter of a Million Cycles

Fast energy storage via intercalation requires quick ionic diffusion and often results in pseudocapacitive behavior. The cycling stability of such energy storage materials remains understudied despite the relevance to lifetime cost. Orthorhombic niobium oxide (T-Nb₂O₅) is a rapid ion intercalation material with a theoretical capacity of 201.7 mAh g⁻¹ (Li₂Nb₂O₅) and good cycling stability due to the minimal unit cell strain during (de)intercalation. Prior reports of T-Nb₂O₅ cycling between 1.3–3.1 V versus Li/Li⁺ noted a 50% loss in capacity after 10 000 cycles. Here, cyclic voltammetry is used to identify the role of the voltage window, state of charge, and potentiostatic holds on the cycling stability of mesoporous T-Nb₂O₅ thin films. Films cycled between 1.2–3.0 V versus Li/Li⁺ without voltage holds (Li_1.1Nb₂O₅) exhibited extreme cycling stability with 90.8% capacity retention after 0.25 million cycles without detectable morphological/crystallographic changes. In contrast, the inclusion of 60 s voltage holds (Li_2.18Nb₂O₅) led to rapid capacity loss with 61.6% retention after 10 000 cycles with corresponding X-ray diffraction evidence of amorphization. Cycling with other limited voltage windows identifies that most crystallographic degradation occurs at higher extents of lithiation. These results reveal remarkable stability over limited conditions and suggest that T-Nb₂O₅ amorphization is associated with high extents of lithiation.     

Tension metastable fluid detection systems for special nuclear material detection and monitoring

Tension metastable fluid states offer unique potential for radical transformation in radiation detection capabilities. States of tension metastability may be obtained in tailored resonant acoustic systems such as the acoustic tension metastable fluid detector (ATMFD) system or via centrifugal force based systems such as the centrifugal tension metastable fluid detector (CTMFD) system; both under development at Purdue University. In this paper we describe research results with CTMFD systems for use in the detection of key actinide isotopes constituting special nuclear materials (SNMs) in spent fuel. Tests in a CTMFD system demonstrate the ability to detect alpha activity (at ∼100% efficiency) of U-isotopes at concentrations of ∼100 ppb (which is unprecedented and about ×100-1000 more sensitive than from conventional liquid scintillation spectroscopy). An inherent capability of TMFD systems concerns on demand tailoring of fluid tension levels allowing for energy discrimination and spectroscopy. This appears especially useful to detect the key isotopes of U and other transuranic isotopes of Pu, Np, Am, and Cm that are at different stages of nuclear fuel reprocessing (i.e., UREX+).     

Ascertaining directionality information from incident nuclear radiation

Unprecedented capabilities for the detection of nuclear particles via tailored resonant acoustic systems such as the acoustic tensioned metastable fluid detection (ATMFD) systems were assessed for determining directionality of incoming fast neutrons. This paper presents advancements that expand on these accomplishments, thereby increasing the accuracy and precision of ascertaining directionality information utilizing enhanced signal processing-cum-signal analysis, refined computational algorithms, and on demand enlargement of the detector sensitive volume. Advances in the development of ATMFD systems were accomplished utilizing a combination of experimentation and theoretical modeling. Modeling methodologies include Monte-Carlo based nuclear particle transport using MCNP5 and multi-physics based assessments accounting for acoustic, structural, and electromagnetic coupling of the ATMFD system via COMSOL's multi-physics simulation platform. Benchmarking and qualification studies have been conducted with a 1 Ci Pu–Be neutron-gamma source. These results show that the specific ATMFD system used for this study can enable detection of directionality of incoming fast neutrons from the neutron source to within 30° with 80% confidence; this required ∼2000 detection events which could be collected within ∼50 s at a detection rate of ∼30–40 per second. Blind testing was successfully conducted for determining the neutron source randomly positioned in space. Results of experimentation were found to be compatible with MCNP5-COMSOL multi-physics model predictions.     

Postdictors of eyewitness errors: Can false identifications be diagnosed?

Eyewitness researchers have "postdicted" identification accuracy using witness confidence (S. L. Sporer, S. Penrod, D. Read, & B. Cutler, 1995), response latency (S. L. Sporer, 1993, 1994), and endorsement of statements consistent with using relative versus absolute judgment strategies (D. Dunning & L. B. Stem, 1994; R. C. L. Lindsay & K. Bellinger, 1999). All of these measures were collected from 321 introductory psychology students who had viewed a staged crime and completed a lineup identification task. Some participants received feedback after identification (G. L. Wells & A. L. Bradfield, 1998). Lineup fairness was also used as a postdictor of eyewitness accuracy. Discriminant function analysis indicated that 75.2% of choosers and 63.0% of nonchoosers were correctly classified. Decision time and lineup fairness were the best postdictors of accuracy. The implications for postdicting real eyewitness decisions are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

DC field dependence of dielectric constant and loss factor of Al2O3-doped barium strontium titanate for application in phased array antennas

DC electric field effects on the real part of the relative dielectric constant and the loss factor of barium strontium titanate for application in phased array antennas have been studied. The real part of the relative dielectric constant of the specimens decreases with increasing applied DC field. The loss factor under bias DC electric field is slighter than the real part of the relative dielectric constant does. The tunability is about 24% for barium strontium titanate doped with 1 wt% Al₂O₃ content. Variation of fitted phenomenological coefficients with Al₂O₃ contents below 10 wt% is small and a rapid increase of the fitted phenomenological coefficient occurs above 10 wt%. Variation of field coefficient A and tunability with Al₂O₃ contents has the same trend as that of the grain size. The real part of the relative dielectric constant of Al₂O₃ doped barium strontium titanate decreases rapidly before 1.0 KV/cm and slowly after 1 KV/cm compare to the data obtained by the curve fitting. There is a conduction loss mechanism other than the intrinsic dielectric loss for the dielectric loss under bias electric field.     

Crystal Symmetry Engineering in Epitaxial Perovskite Superlattices

Interface plays a critical role in determining the physical properties and device performance of heterostructures. Traditionally, lattice mismatch, resulting from the different lattice constants of the heterostructure, can induce epitaxial strain. Over past decades, strain engineering has been demonstrated as a useful strategy to manipulate the functionalities of the interface. However, mismatch of crystal symmetry at the interface is relatively less studied due to the difficulty of atomically structural characterization, particularly for the epitaxy of low symmetry correlated materials on the high symmetry substrates. Overlooking those phenomena restrict the understanding of the intrinsic properties of the as- determined heterostructure, resulting in some long-standing debates including the origin of magnetic and ferroelectric dead layers. Here, perovskite LaCoO₃-SrTiO₃ superlattice (SL) is used as a model system to show that the crystal symmetry effect can be isolated by the existing interface strain. Combining the state-of-art diffraction and electron microscopy, it is found that the symmetry mismatch of LaCoO₃-SrTiO₃ SL can be tuned by manipulating the SrTiO₃ layer thickness to artificially control the magnetic properties. The work suggests that crystal symmetry mismatch can also be designed and engineered to act as an effective strategy to generate functional properties of perovskite oxides.     

What can we monitor over unreliable channels?

International Journal on Software Tools for Technology Transfer - This article addresses the question of what properties can be monitored over an unreliable communication channel. We model...