Applications of analytical electron microscopy to guide the design of boron carbide

Compositional analysis of boron carbide on nanometer length scales to examine or interpret atomic mechanisms, for example, solid-state amorphization or grain-boundary segregation, is challenging. This work reviews advancements in high-resolution microanalysis to characterize multiple generations of boron carbide. First, ζ-factor microanalysis will be introduced as a powerful (scanning) transmission electron microscopy ((S)TEM) analytical framework to accurately characterize boron carbide. Three case studies involving the application of ζ-factor microanalysis will then be presented: (1) accurate stoichiometry determination of B-doped boron carbide using ζ-factor microanalysis and electron energy loss spectroscopy, (2) normalized quantification of silicon grain-boundary segregation in Si-doped boron carbide, and (3) calibration of a scanning electron microscope X-ray energy-dispersive spectroscopy (XEDS) system to measure compositional homogeneity differences of B/Si-doped arc-melted boron carbides in the as-melted and annealed conditions. Overall, the improvement and application of advanced analytical tools have helped better understand processing–microstructure–property relationships and successfully manufacture high-performance ceramics.     

Linguistic frequent pattern mining using a compressed structure

Traditional association-rule mining (ARM) considers only the frequency of items in a binary database, which provides insufficient knowledge for making efficient decisions and strategies. The mining of useful information from quantitative databases is not a trivial task compared to conventional algorithms in ARM. Fuzzy-set theory was invented to represent a more valuable form of knowledge for human reasoning, which can also be applied and utilized for quantitative databases. Many approaches have adopted fuzzy-set theory to transform the quantitative value into linguistic terms with its corresponding degree based on defined membership functions for the discovery of FFIs, also known as fuzzy frequent itemsets. Only linguistic terms with maximal scalar cardinality are considered in traditional fuzzy frequent itemset mining, but the uncertainty factor is not involved in past approaches. In this paper, an efficient fuzzy mining (EFM) algorithm is presented to quickly discover multiple FFIs from quantitative databases under type-2 fuzzy-set theory. A compressed fuzzy-list (CFL)-structure is developed to maintain complete information for rule generation. Two pruning techniques are developed for reducing the search space and speeding up the mining process. Several experiments are carried out to verify the efficiency and effectiveness of the designed approach in terms of runtime, the number of examined nodes, memory usage, and scalability under different minimum support thresholds and different linguistic terms used in the membership functions.

     

Computational Analysis of the Solid-State and Solvation Properties of Carbamazepine in Relation to its Polymorphism

The solvent-dependent polymorphism of the active pharmaceutical ingredient (API) carbamazepine is interpreted from calculations of the solid-state and API-solvent intermolecular interactions. These simulations suggested that apolar solute-solute interactions could be disrupted by apolar solvents. In contrast, the polar solute-solute interactions were found to be easily disrupted by polar and protic solvents. This is consistent with experimental observations that the crystallization of the metastable form II is more dominant in apolar solvents. The Mercury program remains the gold standard in terms of usability; however, further expansion into more complex simulation techniques could make this package of even greater use in pharmaceutical manufacturing workflows.     

Addressing amorphization and transgranular fracture of B4C through Si doping and TiB2 microparticle reinforcing

Over the last two decades, many studies have contributed to improving our understanding of the brittle failure mechanisms of boron carbide and provided a road map for inhibiting the underlying mechanisms and improving the mechanical response of boron carbide. This paper provides a review of the design and processing approaches utilized to address the amorphization and transgranular fracture of boron carbide, which are mainly based on what we have found through 9 years of work in the field of boron carbides as armor ceramics.     

Fate of physical,chemical, and microbial contaminants in domestic wastewater following treatment by small constructed wetlands

In order to evaluate the efficacy of constructed wetlands for treatment of domestic wastewater for small communities located in rural areas, small-scale wetland mesocosms (400 L each) containing two treatment designs (a mixture of Typha, Scirpus, and Juncus species; control without vegetation) were planted into two depths (45 or 60 cm) with pea gravel. Each mesocosm received 19 L/day of primary-treated domestic sewage. Mesocosms were monitored (inflow and outflow samples) on a monthly basis over a 2-year period for pH, total suspended solids (TSS), 5-day biochemical oxygen demand (BOD(5)), total Kjeldahl nitrogen (TKN), dissolved oxygen (DO), and conductivity. Microbiological analyses included enumeration of fecal coliforms, enterococci, Salmonella, Shigella, Yersinia, and coliphage. Significant differences between influent and effluent water quality for the vegetated wetlands (p<0.05) were observed in TSS, BOD(5), and TKN. Increased DO and reduction in fecal coliform, enterococcus, Salmonella, Shigella, Yersinia, and coliphage populations also were observed in vegetated wetlands. Greatest microbial reductions were observed in the planted mesocosms compared to those lacking vegetation. Despite marked reduction of several contaminants, wetland-treated effluents did not consistently meet final discharge limits for receiving bodies of water. Removal efficiencies for bacteria and several chemical parameters were more apparent during the initial year compared to the second year of operation, suggesting concern for long-term efficiency and stability of such wetlands.     

The Relational Aspect to High Reliability Organization

The literature on ‘high reliability organizations’ demonstrates how central reliability is to organizing in certain highly demanding settings. In more mundane settings, however, where there may not be a dominant type of catastrophic failure, the meaning attributed to reliability is less likely to be unambiguous and consensual. It is more likely to be explicitly relational: a quality of the relationship between an entity that is being relied on and an entity that is relying on it. This draws attention to the importance of the relying process in contributing to how a system performs and whether it meets expectations. A field study was carried out in a highway construction and maintenance organization to analyse the various understandings of reliability that organizational members had in different contexts. It found that there were multiple understandings – involving a capacity not only to achieve particular outcomes but also comply with norms, fit behaviour to situations, and communicate about what could and could not be achieved. It also found that reliability problems were not solved in some simple sense. Instead they were transformed into other reliability problems that then had to be managed by further effort or by other organizations. We suggest that recognizing the multiple meanings of reliability, the importance of relying, and the way in which reliability problems are transformed from one form to another all have important practical implications.     

Finite Element Methods for a System of Dispersive Equations

The present study is concerned with the numerical approximation of periodic solutions of systems of Korteweg–de Vries type, coupled through their nonlinear terms. We construct, analyze and numerically validate two types of schemes that differ in their treatment of the third derivatives appearing in the system. One approach preserves a certain important invariant of the system, up to round-off error, while the other, somewhat more standard method introduces a measure of dissipation. For both methods, we prove convergence of a semi-discrete approximation and highlight differences in the basic assumptions required for each. Numerical experiments are also conducted with the aim of ascertaining the accuracy of the two schemes when integrations are made over long time intervals.     

Interpretation d'une controverse scientifique : Strategies argumentatives d'adolescentes et d'adolescents quebecois

Résumé

Actualiser la rhétorique scolaire courante sur les sciences et en présenter une vision plus controversée constitue un enjeu éducatif important en vue de préparer les jeunes du secondaire à débattre de manière éclairée autour d'enjeux sociotechniques contemporains. Pour documenter la manière dont de jeunes québécois et québécoises argumentent autour d'une vision socialisée des sciences, nous avons demandé à sept groupes de trois sujets d'interpréter un débat polémique entre deux scientifiques autour de la question du réchauffement climatique planétaire. Nous présentons dans cet article des extraits de l'analyse argumentative de l'un de ces entretiens. Ces jeunes se sont montrés capables de discuter de questions d'épistémologie et de sociologie de sciences. La conception réaliste et empùïste qui oriente leurs discours sur les sciences rend cependant difficilement admissible l'existence même du désaccord en question. Certains moments de complexification conceptuelle ont cependant émergé en cours de discussion, ce qui nous permet de penser que le type de vignette utilisé dans cette recherche pourrait être transposé en classe afin d'initier des discussions fécondes autour de matières controversées en sciences. De la même manière, les outils d'analyse argumentative mis en ?uvre pourraient être réinvestis avec des élèves pour cerner certaines idées courantes sur les sciences et en questionner la légitimité, favorisant ainsi le développement d'un regard plus averti sur ces dernières.     

Analysing exemplary science teaching

Alsop, S., Bencze, L., & Pedretti, E. (Eds.). (2005). Analysing Exemplary Science Teaching. Maidenhead: Open University Press. ISBN: 0–335–21311–1