Current Understanding of Structure–Processing–Property Relationships in BaTiO3–Bi(M)O3 Dielectrics

As part of a continued push for high permittivity dielectrics suitable for use at elevated operating temperatures and/or large electric fields, modifications of BaTiO₃ with Bi(M)O₃, where M represents a net‐trivalent B‐site occupied by one or more species, have received a great deal of recent attention. Materials in this composition family exhibit weakly coupled relaxor behavior that is not only remarkably stable at high temperatures and under large electric fields, but is also quite similar across various identities of M. Moderate levels of Bi content (as much as 50 mol%) appear to be crucial to the stability of the dielectric response. In addition, the presence of significant Bi reduces the processing temperatures required for densification and increases the required oxygen content in processing atmospheres relative to traditional X7R‐type BaTiO₃‐based dielectrics. Although detailed understanding of the structure–processing–property relationships in this class of materials is still in its infancy, this article reviews the current state of understanding of the mechanisms underlying the high and stable values of both relative permittivity and resistivity that are characteristic of BaTiO₃‐Bi(M)O₃ dielectrics as well as the processing challenges and opportunities associated with these materials.     

Granulocyte colony-stimulating factor and antibiotics in the prophylaxis of a murine model of polymicrobial peritonitis and sepsis

In previous gel-shift assays, we identified a protein complex, referred to as GS1, that binds in a sequence-specific manner to single-stranded DNA and is highly enriched in brain. As an initial step in clarifying the function of this complex, we have undertaken studies aimed at defining its protein components. In particular, we focused on identifying two protein bands that were covalently labeled when the GS1-DNA complex was subjected to UV irradiation to induce cross-linking between the radiolabeled probe and GS1 components. By following GS1 binding activity through a series of conventional chromatographic steps, as well as an affinity column based on the DNA oligonucleotide used for gel-shift assays, we were able to achieve approximately 500,000-fold enrichment of GS1 compared with that in crude cerebellar extracts used as starting material. This highly purified fraction contained both protein bands detected by UV cross-linking in crude extracts. Sequencing of peptides derived from these proteins led to their identification as Translin and Trax, interacting proteins identified in studies of DNA recombination in lymphocytes. A distinct line of research has provided evidence that a complex containing Translin can bind to specific mRNAs and block their translation. Whether one or both of these proposed functions of the Translin/Trax complex explains the high basal level of GS1 binding activity present in the brain remains to be determined.     

Autobiography in Teaching History of Psychology.

In a course in the history of psychology, some different procedures were tried recently which might be of interest to others teaching in this area. The course has in the past attempted to analyze some major historical trends and a few topics in philosophy of science which are important for psychology. Upper division and graduate students may enroll, but 80-90% are in the latter group. Much of the success of activities outlined in this article depends on having a small class and a group of energetic, sophisticated students. While it is often emphasized that much scientific progress can be understood in terms of such factors as social climate and interdisciplinary penetration, the "autobiographical" procedure reminds us forcefully that a large proportion of research motivation and success is related to a somewhat different cluster of variables to which we may attach the label, "People." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Titanium diboride–silicon carbide–boron carbide ceramics with super‐high hardness and strength

Triplex particulate composites composed of boride and carbide ceramics were found to have high strength, hardness, and fracture toughness values. Two compositions consisting of 70:15:15 and 1:1:1 volume ratios of TiB_2, SiC, and B₄C were produced from commercially available powders by hot‐pressing. The 70:15:15 ceramic exhibited a strength of ~1.3 GPa, while the 1:1:1 ceramic had a strength of ~0.9 GPa. These strengths are comparable to super‐strong Y₂O₃‐PSZ and β‐SiAlON based composites. The Vickers’ hardness values of these ceramics were ~32 GPa for indent loads of 9.8 N. Hardness increased as indentation load decreased. The 1:1:1 ceramic had a hardness of ~53 GPa at an indentation load of 0.49 N, higher than values reported for so‐called “super‐hard” ceramics, and comparable to c‐BN.     

Growth of α-AI2O3 Platelets in the HF-γy-AI2O3 System

In the presence of a fluorine mineralizer, highly aggregated, <5 μm α-Al₂O₃ platelet particles form by vapor transport during the thermal transformation of γ-alumina. Platelet aggregation was determined to occur by platelet inter-growth and by edge nucleation on primary α-Al₂0₃ platelets. The addition of 10¹⁰α-alumina seed particles/cm³γ–Al₂O₃ resulted in the development of discrete particles during the initial stage of transformation. Impingement of the growing platelets during the latter stage of transformation, however, resulted in intergrowth, a process which was not changed by seeding. Particle size distribution broadening was observed to increase with increasing HF and H₂O concentrations because vapor reactant supersaturation increases the degree of edge nucleation. When initially low HF and H₂O concentrations were used in seeded systems, however, essentially aggregate-free α-Al₂O₃ platelets of 10–15 μm were obtained.     

Methods of assessing strategies for judging covariation between events.

Investigated method of assessment as one possible source of the poor agreement in research about strategies people use to assess covariation between events. A set of problems was developed in such a way that different judgment rules would produce different decisions about the relationships between events. 116 college students (aged 18–32 yrs) judged these problems and were then asked to explain their judgment strategy. In addition, they were shown model strategies and asked to choose the one like their own strategy and the model that would be the best strategy. Ss whose judgments indicated use of the most sophisticated strategy were quite accurate in reporting their judgment rules. Ss using the less accurate rules most commonly reported using strategies that could not have produced the obtained pattern of problem solutions. These findings suggest that self-report is a weak basis for conclusions about sources of error in covariation judgment. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)