Atomic layer deposition onto carbon fiber fabrics

Carbon fiber fabrics, consisting of interwoven bundles of 3000 single fibers, were coated with Al₂O₃ using the atomic layer deposition (ALD) process, exposing the fabrics to alternating pulses of trimethyl aluminium and water vapors. The thickness and uniformity of the coatings were investigated using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The obtained coatings were conformal, 84 ALD cycles gave rise to approximately 20‐nm‐thick coatings and 168 ALD cycles to approximately 40‐nm‐thick coatings. It was found, that a uniform coating can be obtained at a purge time of 40 seconds. Reducing purge times below 20 seconds gives rise to increased particle growth and thus the coating becomes inhomogeneous. Initially, the samples that were coated had a size of 2×10 cm (thickness 0.3 mm). The size of the fabric was subsequently increased up to 8×20 cm and a uniform coating of the same quality was obtained. By oxidizing the coated fabrics, fabrics composed of interwoven alumina microtubes were obtained. Infiltration of the microtubes with solutions of two distinguishable fluorescent dyes showed that interchange of the dyes between warp and weft microtubes occurs, but is absent at approximately 20% of the crossovers. Taking all our findings into account, we conclude that the majority of the fibers were separated from each other by the coating prior to the oxidation. This work demonstrates that ALD is a suitable method to produce thin, conformal coatings on the surface of carbon fiber fabrics.     

Pyrrolic‐Type Nitrogen‐Doped Hierarchical Macro/Mesoporous Carbon as a Bifunctional Host for High‐Performance Thick Cathodes for Lithium‐Sulfur Batteries

Lithium‐sulfur (Li‐S) batteries are highly considered as a next‐generation energy storage device due to their high theoretical energy density. For practical viability, reasonable active‐material loading of >4.0 mg cm^?2 must be employed, at a cost to the intrinsic instability of sulfur cathodes. The incursion of lithium polysulfides (LiPS) at higher sulfur loadings results in low active material utilization and poor cell cycling capability. The use of high‐surface‐area hierarchical macro/mesoporous inverse opal (IOP) carbons to investigate the effects of pore volume and surface area on the electrochemical stability of high‐loading, high‐thickness cathodes for Li‐S batteries is presented here. The IOP carbons are additionally doped with pyrrolic‐type nitrogen groups (N‐IOP) to act as a polar polysulfide mediator and enhance the active‐material reutilization. With a high sulfur loading of 6.0 mg cm^?2, the Li‐S cells assembled with IOP and N‐IOP carbons are able to attain a high specific capacity of, respectively, 1242 and 1162 mA h g^?1. The N‐IOP enables the Li‐S cells to demonstrate good electrochemical performance over 300 cycles.     

Anisotropy of bituminous mixture in the linear viscoelastic domain

Some anisotropic properties in the linear viscoelastic domain of bituminous mixtures compacted with a French LPC wheel compactor are highlighted in this paper. Bituminous mixture is generally considered as isotropic even if the compaction process on road or in laboratory induces anisotropic properties. Tension–compression complex modulus tests have been performed on parallelepipedic specimens in two directions: (i) direction of compactor wheel movement (direction I, which is horizontal) and (ii) direction of compaction (direction II, which is vertical). These tests consist in measuring sinusoidal axial and lateral strains as well as sinusoidal axial stress, when sinusoidal axial loading is applied on the specimen. Different loading frequencies and temperatures are applied. Two complex moduli, \(E_{\mathrm{I}} ^{*}\) and \(E_{\mathrm{II}}^{*}\), and four complex Poisson’s ratios, \(\nu_{\text{II-I}}^{*}\), \(\nu_{\text{III-I}}^{*}\), \(\nu_{\text{I-II}}^{*}\) and \(\nu_{\text{III-II}}^{*}\), were obtained. The vertical direction appears softer than the other ones for the highest frequencies. There are very few differences between the two directions I and II for parameters concerning viscous effects (phase angles \(\varphi(E_{\mathrm{I}})\) and \(\varphi(E_{\mathrm{II}})\), and shift factors). The four Poisson’s ratios reveal anisotropic properties but rheological tensor can be considered as symmetric when considering very similar values obtained for the two measured parameters (I-II and II-I)In addition, an anisotropic 3 dimensional version of the “2S2P1D” (2 springs, 2 parabolic creep elements and 1 dashpot) model, developed at the University of Lyon—ENTPE laboratory, is presented and used to simulate experimental results. The model simulation provides a good fit to the data. Stability of the material could also be investigated on the whole frequency–temperature range.     

A quadratic edge-finding filtering algorithm for cumulative resource constraints

The cumulative scheduling constraint, which enforces the sharing of a finite resource by several tasks, is widely used in constraint-based scheduling applications. Propagation of the cumulative constraint can be performed by several different filtering algorithms, often used in combination. One of the most important and successful of these filtering algorithms is edge-finding. Recent work by Vilím has resulted in a ?? (kn log n) algorithm for cumulative edge-finding (where n is the number of tasks and k is the number of distinct capacity requirements), as well as a new related filter, timetable edge-finding, with a complexity of ??(n ²). We present a sound ??(n ²) filtering algorithm for standard cumulative edge-finding, orthogonal to the work of Vilím; we also show how this algorithm’s filtering may be improved by incorporating some reasoning from extended edge-finding, with no increase in complexity. The complexity of the new algorithm does not strictly dominate previous edge-finders for small k, and it sometimes requires more iterations to reach the same fixpoint; nevertheless, results from Project Scheduling Problem Library benchmarks show that in practice this algorithm consistently outperforms earlier edge-finding filters, and remains competitive with timetable edge-finding, despite the latter algorithm’s generally stronger filtering.     

The effect of Cr alloying on defect migration at Ni grain boundaries

Journal of Materials Science - Mass transport along grain boundaries in alloys depends not only on the atomic structure of the boundary, but also its chemical make-up. In this work, we use...     

“Effectiveness of comprehensive professional development for teachers of at-risk preschoolers”: Correction.

Reports an error in "Effectiveness of comprehensive professional development for teachers of at-risk preschoolers" by Susan H. Landry, Jason L. Anthony, Paul R. Swank and Pauline Monseque-Bailey (Journal of Educational Psychology, 2009[May], Vol 101[2], 448-465). In the article, a disclosure statement was incorrectly omitted due to an error during the production process from the author note of the final article. The following statement should have appeared in the author note: The University of Texas Health Science Center—Houston owns intellectual property for the online professional development program and the progress monitoring program and receives remuneration as do Paul Swank and Susan Landry as two of the authors of those programs. (The following abstract of the original article appeared in record 2009-04640-017.) This study compared effectiveness of “business as usual” to that of 4 professional development (PD) programs that targeted teachers of at-risk preschool children. A 2 × 2 design was used to cross mentoring and progress monitoring conditions among the 4 PD programs. Specifically, some teachers received both in-classroom mentoring and detailed, instructionally linked feedback concerning children's progress in language and literacy. Some teachers received no mentoring but did receive the detailed, instructionally linked feedback concerning children's progress. Some teachers received in-classroom mentoring but only limited feedback on children's progress, which was not linked to curricular activities. Finally, some teachers received no mentoring and only limited feedback concerning children's progress. All 4 PD conditions included the same year-long, facilitated online course that emphasized language and literacy instruction, practice of learned material in one's classroom, and participation in online message boards with fellow teachers. Across 4 states, 158 schools (N = 262 classrooms) were randomly assigned to 1 of the 4 PD conditions or business as usual. The condition that included online coursework combined with mentoring and detailed, instructionally linked feedback yielded the greatest improvements in teaching behavior and children's school readiness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effectiveness of comprehensive professional development for teachers of at-risk preschoolers.

[Correction Notice: An erratum for this article was reported in Vol 101(3) of Journal of Educational Psychology (see record 2009-11043-017). In the article, a disclosure statement was incorrectly omitted due to an error during the production process from the author note of the final article. The following statement should have appeared in the author note: The University of Texas Health Science Center—Houston owns intellectual property for the online professional development program and the progress monitoring program and receives remuneration as do Paul Swank and Susan Landry as two of the authors of those programs.] This study compared effectiveness of “business as usual” to that of 4 professional development (PD) programs that targeted teachers of at-risk preschool children. A 2 × 2 design was used to cross mentoring and progress monitoring conditions among the 4 PD programs. Specifically, some teachers received both in-classroom mentoring and detailed, instructionally linked feedback concerning children's progress in language and literacy. Some teachers received no mentoring but did receive the detailed, instructionally linked feedback concerning children's progress. Some teachers received in-classroom mentoring but only limited feedback on children's progress, which was not linked to curricular activities. Finally, some teachers received no mentoring and only limited feedback concerning children's progress. All 4 PD conditions included the same year-long, facilitated online course that emphasized language and literacy instruction, practice of learned material in one's classroom, and participation in online message boards with fellow teachers. Across 4 states, 158 schools (N = 262 classrooms) were randomly assigned to 1 of the 4 PD conditions or business as usual. The condition that included online coursework combined with mentoring and detailed, instructionally linked feedback yielded the greatest improvements in teaching behavior and children's school readiness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

AN IMPROVED COMPACT INTEGRATED ANALYTICAL SWATCH TESTING SYSTEM

A compact swatch testing system has been developed to precisely quantify the permeation and penetration of a chemical weapons agent simulant while reducing the system footprint, improving safety and usability, enhancing automation, and maintaining measurement precision comparable to its predecessor. With the addition of a new test cell design and temperature control mechanism, the improved system demonstrated higher steady-state permeation rates and shorter breakthrough times. In comparison to the earlier prototype, the compact configuration's footprint and volume are reduced substantially, thereby allowing for use inside a 6-foot laboratory hood. A reference device for assessing test cell performance was also developed.     

An international quality assurance (proficiency testing) scheme for the quantitated determination of daidzein,genistein and glycitein in infant formula

This quality assurance (proficiency testing) scheme was commissioned to enable the Food Standards Agency (FSA) to determine the quality of analytical results submitted by researchers measuring the concentrations of phytoestrogens in foods in FSA funded research projects and to demonstrate that FSA funded laboratories are producing consistent and precise results. Non-FSA funded laboratories from around the world were also invited to join in the scheme to increase the number participants. A secondary objective was to highlight the most successful methodologies used to analyse phytoestrogens.