Effects of burial powder configuration on the microstructure,composition, and ion conductivity of perovskite Li3xLa1/3-xTaO3 ion conductors

A combustion synthesis methodology for the preparation of perovskite Li_3xLa_1/3-xTaO₃ lithium-ion conductors with x = 0.033 is presented. Bulk ceramic specimens were sintered under combinations of burial powder and cover crucibles to provide different lithium vapor overpressure conditions. A maximum total lithium ion conductivity of 6 × 10^-6 S cm^-1 at room temperature was found for the pellet covered by a crucible whose lip was sealed using parent powder (moderate overpressure), with agreement to the maximum in the intergranular ion conductivity. Intragranular conductivity was maximized at the low overpressure condition. The trend in ion conductivity was found to correspond to the lithium content in the samples through a combination nuclear reaction analysis and energy dispersive X-ray spectroscopy phase constitution measurements. The mechanism impacting ion conductivity was determined to be changes in the amount of LaTaO₄ secondary phase as driven by the processing conditions during sintering.     

Mechanical properties of ZrB2 ceramics determined by two laboratories

The mechanical properties for zirconium diboride (ZrB₂) were measured at two laboratories and compared. Two billets of ZrB₂ were prepared by hot-pressing commercial powder. The relative densities of the billets were >99% and with an average grain size of 5.9 ± 4.5 µm. Both laboratories prepared American Society for Testing and Materials (ASTM) C1161 B-bars for strength and ASTM C1421 bars with notch configuration A for fracture toughness. Specimens were machined by diamond grinding at the Army Research Laboratory (ARL) and electrical discharge machining (EDM) at Missouri S&T. Strength bars tested at Missouri S&T were polished to a .25 μm finish while the bars were tested as-ground at ARL. Strengths were 473 ± 79 MPa for the Missouri S&T bars and 438 ± 68 for the ARL bars while the fracture toughness values were 3.9 ± .7 MPa•m^1/2 for the Missouri S&T bars and 4.4 ± .6 MPa•m^1/2 for the ARL bars. Vickers hardness was measured by both laboratories over a range of indentation loads. The resulting hardness values were on the low end of previously reported values and were quite different from each other especially at indentation loads ≤20N. The study demonstrated that the properties of materials tested to ASTM standards at different laboratories can be compared directly. In addition, strength and fracture toughness were nearly identical for bars prepared by conventional diamond grinding or EDM.     

Adsorption,Desorption, Resorption

The complete characterization of batch adsorption from solution, desorption, and related phenomena have been interpreted in the light of a general equation. The forward and reverse adsorption-rate constants and the adsorptive capacity comprise the only parameters. Where adsorption alone is of importance and the desorption-rate constant can be neglected, a simplified form of the theory results in a special equation which may suffice for most adsorption purposes. In either case, the characteristic parameters are determinable from the data and serve as criteria for comparing similar systems. The theory has been confirmed by the data of various investigators taken from the literature. The parameters derived from column adsorption are in agreement with the corresponding batch-derived parameters. The limitations as well as the capabilities of the theory are presented; but even where deviations from the assumed model exist, the results are useful.     

Ozonation/Post-Chlorination of Humic Acid: A Model for Predicting Drinking Water Disinfection By-Products

Experiments were performed to evaluate disinfection by-products in model humic acid solutions which were ozonated at three different ozone to carbon levels and then chlorinated. These experiments were conducted in order to help understand whether the ozone/post-chlorination process alters the amount and type of mutagenic by-products formed, from those produced by chlorination of humic acid alone. Disinfection by-products were identified by gas chromatography/mass spectrometry (GC/MS). Samples of clarified and sand-filtered Mississippi River water at a pilotscale drinking water treatment plant in Jefferson Parish, Louisiana, that were ozonated and post-disinfected with chlorine, also were analyzed by GC/MS. A comparison of the by-products in the pilot plant study versus those in our laboratory study showed that similar compounds were produced. The effect of bromide ion in the pilot plant water on by-product formation also is discussed.     

Scale-sensitivity, fractal analysis and simulations

The scale-of-interaction is presented as a criterion for establishing functional correlations. It is also used in simulating interactions with rough surfaces. Fractal analysis by the patchwork method is discussed and is used as the basis for evaluating data acquisition systems. The patchwork method is also used as the basis for simulating interactions with the surface. The essence of the simulation is to understand macroscopic, apparently continuous, interactions as the sum of a large number of discrete interactions at some appropriately fine scale. The simulations shown here use topographic data acquired from engineering surfaces.     

Determination of oxygen and nitrogen in coal by instrumental neutron activation analysis

The purpose of this study was to measure oxygen and nitrogen in coals using instrumental neutron activation analysis. For six U.S. coals total oxygen ranged from 9.4 to 28.7% and total nitrogen varied from 0.72 to 1.61%. To obtain values of organic oxygen and nitrogen either a low-temperature-ashing method or an acid-treatment method was suitable for bituminous coals. The mean difference of the experimentally determined values (O_dmmf)_LTA ? (O_dmmf)_AT = ?0.82, s = 0.51, was found to be statistically significant at the 95% confidence level, but the comparable difference for nitrogen was not. By the LTA method oxygen and nitrogen on the dmmf basis for bituminous coals showed no statistically significant difference with calculated dmmf values. Nitrogen was detected in all the LTAs varying from 0.38 to 1.67%. Formation of insoluble CaF₂ in the acid-treatment method caused an interference in the nitrogen determination due to the ¹⁹F (n, 2n) ¹⁸F reaction but was correctable. In addition, recoil proton reactions on C and O leading to the formation of ¹³N must be accounted for in all nitrogen determinations in the coal matrix.     

New Technology for Preventing Residential Electrical Fires: Arc-Fault Circuit Interrupters (AFCIs)

A new generation of residential electrical branch circuit breakers that incorporates technology to detect and mitigate the effects of arcing faults is described. Fire loss estimates attributed to electrical wiring and the development of the arc-fault circuit interrupter for the prevention of residential electrical fires are discussed. The industry voluntary standard for arc-fault circuit interrupters as well as the 1999 National Electrical Code requirement are reviewed.     

Acceleration of changes in session impact during contrasting time-limited psychotherapies.

Following the suggestion that therapeutic change is accelerated in time-limited psychotherapy, this study investigated the across-session patterns of session impact in the treatments of 117 depressed clients who were randomly allocated to 8 or 16 sessions of cognitive-behavioral (CB) or psychodynamic-interpersonal (PI) therapy. After each session, all clients completed the Session Evaluation Questionnaire and 75 of the clients completed the Session Impacts Scale. Session ratings indicated that sessions were perceived increasingly positively on most impact dimensions (e.g., session depth and smoothness, relationship with the therapist, feelings of understanding and problem solving, postsession positive mood) as treatment progressed. Early in treatment, PI therapy sessions were less smooth (i.e., more tense and uncomfortable) and less focused on problem solving, but PI sessions changed more rapidly than CB sessions on these dimensions, so that later in treatment, sessions of both treatments were equivalently positive. In both treatments, the trend toward more positive sessions was more rapid (i.e., the across-session slope was steeper) in 8-session treatments than in 16 session treatments. Such accelerated changes in session impact may reflect the suggested acceleration … (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Virtual Design Review

In this article we discuss an approach to supporting the design review process of architect/engineering (AE) offices using technologies developed for the World Wide Web. Called the virtual design review, this approach allows a group of reviewers to work simultaneously on a three‐dimensional representation of an incomplete building model. We attempt to improve the way reviewers work in three significant ways: (1) in handling (viewing, retrieving, and storing) information, (2) facilitating interaction between reviewers and between reviewers and designers, and (3) changing the role of reviewers in the design review process by providing autonomous or semiautonomous agents that are capable of performing parts of the design review process. In providing a flexible, open, and robust environment for interaction, the virtual design review draws on lessons learned in the field of computer‐supported cooperative work (CSCW). A survey of the state of the art indicates that most of the critical technologies for the virtual design review already exist; however, issues such as limited network bandwidth and efficient multiparty audio conferencing still need to be addressed.