Some comments about “Comment on hardness definitions”, by J. Malzbender [J. Eur. Ceram. Soc. 23 (2003) 1355–1359]

Malzbender has suggested a model to determine hardness and elastic modulus as a function of the mechanical energies involved during tip penetration in instrumented indentations tests. However, the values obtained with these expressions are not consistent with the ones determined by the well-accepted Oliver and Pharr method. After revision, based on Malzbender's study itself, equations were rewritten and then, the obtained indentation hardness (H) for soda-lime glass was in agreement with the literature data. However, the reduced elastic modulus (E_r) was still about 20% higher than the values in the literature. Developing Malzbender's proposal by the inclusions of additional mechanical energy assumptions, a new expression for E_r is now suggested. Using the new expression, the hardness and reduced elastic modulus agreed very well with the Oliver and Pharr method.     

Reduction and catalytic behaviour of heterobimetallic copper–lanthanide oxides

The reduction of the heterobimetallic copper–lanthanide oxides 2CuO·CeO₂ and 3CuO·Ln₂CuO₄ (Ln = La, Pr, Nd) was studied by H₂-TG/DTA and H₂-TPR. All systems exhibit two main reduction steps accompanied by mass losses in the temperature range 20–1000 °C. The first step was attributed to CuO reduction, whereas the second step is due either to copper reduction in the Ln₂CuO₄ phase with the concomitant formation of Ln₂O₃ or to the surface reduction of CeO₂. The products were characterized by XRD, SEM, EDX, and BET techniques and are better described as supported copper type materials. They were active for the mesityl oxide (4-methyl-2-penten-2-one) gas phase hydrogenation.     

Modeling homophily over time with an actor-partner interdependence model.

Selection and socialization have been implicated in friendship homophily, but the relative contributions of each are difficult to measure simultaneously because of the nonindependent nature of the data. To address this problem, the authors applied a multiple-groups longitudinal actor-partner interdependence model (D. A. Kashy & D. A. Kenny, 2000) for distinguishable dyads to 3 consecutive years of intoxication frequency data from a large community-based sample of Swedish youth. Participants, ranging from 12 to 18 years old (M = 14.35, SD = 1.56) at the start of the study, included 902 adolescents (426 girls and 476 boys) with at least one reciprocated friend during at least one time point and 212 adolescents (84 girls and 128 boys) without reciprocated friends at any time. Similarity estimates indicated strong effects for selection and socialization in friends' intoxication frequency. Over time, younger members of these dyads had less stable patterns of intoxication than older members, largely because younger partners changed their drinking behavior to resemble that of older partners. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The O.R.T. (the Object Relations Technique): A reintroduction.

The purpose of my writing this essay is to familiarize readers with an interesting projective device called the O.R.T. (the Object Relations Technique), which has been described by James Grotstein as “an innovative and unique descendent of the heritage of projective testing on one hand and of projective aspects of psychoanalytic clinical technique on the other (1993, pp. 1).” It is an objectified (operationalized) method for the assessment of an individual’s actual, underlying models for relationship that has been employed primarily as a clinical therapeutic tool. Its history is as interesting as the technique itself. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermal degradation of high‐temperature fluorinated polyimide and its carbon fiber composite

High‐temperature polymers are being used for a broad range of applications, such as composite matrices for structural applications (e.g., high speed aircraft). Polyimides are a special class of polymers that meet the thermal and oxidative stability requirements for high temperature composite aerospace applications. A weight loss study was performed on a fluorinated polyimide resin and its carbon fiber composite in an effort to determine its thermal stability and degradation mechanisms. Experiments were conducted using a preheated oven and thermogravimetric analysis to obtain the weight loss. Regardless of the method used, the resin and composite exhibited excellent thermal stability (less than 1% weight loss) below 430°C, regardless of 2–20 min of exposure. After 20 min of exposure at 510°C, the composite remained relatively stable with only 5.3% weight loss using the oven technique, whereas the neat polyimide sustained 12.6%. When degradation occurred, it was found to be the result of thermolysis and oxidation (to a lesser extent). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Spinodal clustering induced dewetting and non-monotonic stabilization of polymer blend films at high nanofiller concentrations

We examine the effects of high fullerene nanoparticle (f-NP) concentrations, ?_f-NP ∼ (10–20) mass% on polystyrene (PS)/polybutadiene (PB) blend thin film stability. Dewetting of the polymer blend around spinodally clustered f-NPs in this high concentration limit leads to a spinodal like dewetting morphology. This is in contrast to our previously observed results on the stabilization effects of f-NPs on PS/PB blend thin films in the intermediate f-NP concentration range of 7–10 mass%, wherein, after saturating the polymer–blend interface, the NPs stabilize the film by segregating to the blend–substrate interface. We determine three regimes of polymer blend film stability as a function of filler concentration: a) ?_f-NP < 7 mass% where preferential segregation of the f-NPs to the polymer–polymer interface leads to macroscopic dewetting, b) ?_f-NP ∼ (7–10) mass% where PS/PB blend films exhibit complete film stability, and c) ?_f-NP ∼ (11–20) mass%, where spinodal clustering of the f-NPs gives rise to polymer–NP phase exclusion and subsequent dewetting.     

Synthesis and characterization of olivine LiNiPO4 for aqueous rechargeable battery

LiNiPO₄ belongs to a family of olivine type compounds, with members LiMPO₄ where M = Fe, Mn, Co or Ni are transition metals. The lithium nickel phosphate was prepared and characterized in order to evaluate a new potential cathode material for our ongoing research in aqueous rechargeable batteries. Annealing the final product is critical in obtaining the stoichiometric LiNiPO₄ pure phase; conventional cooling to a room temperature leads to an indication of Li₃PO₄ and NiO secondary phases as impurities. The synchrotron infrared radiation (SR-IR) as a source for IR spectroscopy pins down the differences in the chemical bonding for annealed and conventional cooled LiNiPO₄ samples. The cyclic voltammetric and galvanostatic studies showed annealed LiNiPO₄ is electrochemically active from which lithium ions can be de-intercalated during oxidation process leading to an amorphous NiPO₄ and a minor product of nickel(II) hydroxide (β-NiOOH). During subsequent reduction, lithium ions are not fully intercalated, however, the structure is reversible and adequate for multiple cycles. The high potential in LiNiPO₄ looks to be very attractive in terms of high energy density, given the efficiency is improved.