Influence and role of potassium in the reduction of hematite with CO/CO2

Potassium is known for having a favourable role in the reduction of hematite, either pure or as ore and a detrimental action on the crystals’ mechanical properties. However, several different interpretations have been put forward by previous authors: softening of the gangue, modification of the sintering process, consequences of the alkali penetration into the oxide lattices. Hence new data are desirable and have been recorded, with pure hematite crystals as well as with an hematite ore and with two doping techniques: immersion in a K₂CO₃ solution, or introduction of potassium components in the reducing gas. Microstructure investigation shows that potassium favours porous magnetite growth rather than lamellar growth and concentrates in a sublayer of magnetite at the inner interface. In fully reduced crystals, potassium lies mainly in the core of the particle. When the interface has a so-called topochemical configuration, the shrinking core model provides the rate constants as a function of temperature. Arrhenius plots lead to the conclusion that potassium significantly lowers the activation energy. The proposed interpretation is based on the transient formation of KFe₁₁O¹⁷, which is revealed by 3 different observations. It may act as a nucleation catalyst, thanks to easy epitaxy with Fe₂O₃. This is consistent with the change to porous rather than lamellar domains when potassium is brought into play and with the increased crystal fracturation. Hematite ore is less sensitive to potassium because its silica gangue behaves as a trap for it, as shown by treatment with HF before reduction.     

Tacticity dependence of excimer formation in polystyrene solutions

Summary This work deals with the excimer formation in dilute solution for a series of polystyrenes of various tacticity prepared by epimerization of an initial isotactic sample. The main result is that the relative excimer yield remains equal to that obtained for iPS if the percentage of isotactic dyads is higher than 65%.The range of energy migration could be roughly approximated to 6 chromophores.     

Effect of referent object familiarity on verbal learning in the sighted and the blind.

Tested whether the concrete-noun effect is due to the way in which concrete concepts are coded in semantic memory or whether the effect can be attributed to the process of generating compound spatial images, using 5 paired-associate tasks. In Exp I, with 16 sighted undergraduates and 16 congenitally blind Ss (aged 24–60 yrs), results from recall tests indicate that both groups remembered nouns with referents highly familiar to the blind better than nouns with referents of low familiarity to the blind. This effect was unexpected for the sighted because the referents of low familiarity to the blind (e.g., sky, dawn, tower) had presumably been visually experienced by the sighted. Exps II–V, with 220 undergraduates, examined why the extent to which the blind are familiar with an object predicted verbal learning for the sighted in Exp I. Results suggest that referents familiar to the blind were also familiar to the sighted. It is concluded that it is the extent of perceptual experience with a noun's referent, irrespective of the modality through which the experience is acquired, that determines ease of verbal learning. The noun lists are appended. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermomechanical postbuckling of multilayered composite panels with cutouts

The results of a study of the detailed thermomechanical postbuckling response characteristics of flat unstiffened composite panels with central circular cutouts are presented. The panels are subjected to combined temperature changes and applied edge loading (or edge displacements). The analysis is based on a first-order shear deformation plate theory. A mixed formulation is used with the fundamental unknowns consisting of the generalized displacements and the stress resultants of the plate. The postbuckling displacements, transverse shear stresses, transverse shear strain energy density, and their sensitivity coefficients are evaluated. The sensitivity coefficients measure the sensitivity of the post-buckling response to variations in the different lamination and material parameters of the panel. Numerical results are presented showing the effects of the variations in the hole diameter, laminate stacking sequence, fiber orientation, and aspect ratio of the panel on the thermomechanical postbuckling response and its sensitivity to changes in panel parameters.     

Dysfunctional attitudes are mood-state dependent.

To test the hypothesis that self-report of dysfunctional attitudes is mood-state dependent, dysfunctional attitudes were assessed in 43 women before and after they received a depressed or elated mood induction. As predicted, the mood induction produced reliable changes in mood and in dysfunctional attitudes, although the increase in dysfunctional attitudes following the negative mood induction was not large enough to be statistically significant. We also tested the hypothesis, from the cognitive theory of depression, that subjects with previous episodes of depression would report more dysfunctional attitudes than would subjects without such a history. As predicted, subjects who reported previous episodes of depression endorsed more dysfunctional attitudes than did subjects who did not report such a history. However, this effect occurred only for subjects who were in a negative mood state when their dysfunctional attitudes were assessed. These findings support the proposition of the cognitive theory that dysfunctional attitudes are traits but suggest that these traits are mood-state dependent. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sequence of a 7·8 kb segment on the left arm of yeast chromosome XI reveals four open reading frames,including the CAP1 gene,an intron-containing gene and a gene encoding a homolog to the mammalian UOG-1 gene

We report here the DNA sequence of a segment of chromosome XI of Saccharomyces cerevisiae extending over 7·8 kb. The segment contains four long open reading frames, YKL150, YKL153, YKL155 and YKL156, YKL155 corresponds to the CAP1 gene. YKL153 contains an intron and shows an extremely biased codon usage suggestive of a highly expressed protein. YKL156 is a homolog to UOG-1, an open reading frame associated with the cDNA clone of the mammalian growth/differentiation factor 1. YKL150 reveals common motifs to both the RNA polymerase II elongation factor of Drosophila melanogaster and to the yeast PPR2 gene product.     

Childhood abuse and current psychological functioning in a university counseling center population.

84 university counseling center clients (61 women and 23 men) self-reporting childhood physical, sexual, or emotional abuse (n?=?30) or no childhood abuse (n?=?54) completed 3 measures of psychological functioning. Multivariate analysis of variance revealed that clients reporting abuse were more depressed (with the mean Beck Depression Inventory score in the borderline clinical depression range), had more symptomatology (with the mean Global Severity Index of the Brief Symptom Inventory at about the average level of a psychiatric outpatient population), and scored higher on the Borderline Personality scale of the Millon Clinical Multiaxial Inventory (with the mean base-rate score near the cutoff score for presence of borderline personality features). 19 clients reporting emotional abuse only did not differ on any measure from 11 clients reporting sexual or multiple forms of abuse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Type and amount of dietary fat affect relative concentration of cholesterol in blood and other tissues of calves

Sixteen male Holstein calves consumed by nipple a reconstituted milk containing nonfat dry milk and either soybean oil or tallow for 24 weeks. Calves fed milk in this manner (with no dry feed) are functionally nonruminants because the milk bypasses the ruminoreticulum. The fat in these diets contributed about 30% of total dietary calories. The calves consuming soybean oil milk had significantly greater amounts of cholesterol in blood plasma and adipose tissue than did the calves consuming tallow milk.     

Antagonism of [3H]fatty acid incorporation into vimentin by sodium pyruvate: Pitfalls of protein acylation

In the course of studying possible fatty acid acylation of vimentin by cultured bovine lens epithelial cells, several potential pitfalls of protein-fatty acid acylation were recognized. Even exhaustive delipidation of vimentin with organic solvents failed to remove all noncovalently associated [³H]palmitate and [³H]myristate. Hydroxylamine treatment of vimentin, separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE), failed to remove either palmitate or myristate derived radiolabel. Hydroxylamine treatment did remove palmitate label from a group of lower molecular weight proteins. The myristate radiolabel associated with vimentin recovered after SDS-PAGE and subjected to acid hydrolysis was shown due to incorporated [³H]amino acids, mainly glutamic acid, generated from the fatty acid. Adding excess sodium pyruvate to labeling media has been used by others to reduce the metabolic conversion of fatty acids to amino acids; however, no direct evidence in support of this antagonism was presented. We observed that inclusion of sodium pyruvate at between 5 and 20 mM in the labeling medium produced a dramatic decrease in incorporation of myristic acid radiolabel into vimentin. However, inclusion of even 20 mM pyruvate did not completely antagonize the metabolic conversion of fatty acid label to amino acids. Furthermore, the sodium pyruvate antagonism could be totally obscured if the exposure of X-ray film by fluorography was even slightly prolonged. The results illustrate the danger in assuming that solvent extraction totally delipidates proteins and that adding sodium pyruvate to labeling media prevents the transfer of fatty acid label to amino acids. Caution is necessary to conclude that radiolabel associated with specific proteins following incubation of cells with labeled fatty acid is due to covalent attachment of the fatty acid to the protein.