A tribotesting method for evaluating cemented carbide tribo-performance

The abrasive wear properties of materials in sliding contact with solid mineral particles during the comminution process have been studied. The equipment used can simulate the tribo-conditions inside coal pulverisers. Using this experimental apparatus, a number of different cemented tungsten carbides have been tested and classified according to their resistance to abrasive wear in rubbing contact with particulate coal. The paper shows that the wear results can be used to estimate the resistance of a material to brittle fragmentation and chipping of the edges during tribo-contact with solid particles. An equation is presented which enables calculation of the fracture resistance factor, K_WR, based on results from carefully controlled repeated abrasion tests.     

Multiple forms of the U2 small nuclear ribonucleoprotein auxiliary factor U2AF subunits expressed in higher plants

Requirements for intron recognition during pre-mRNA splicing in plants differ from those in vertebrates and yeast. Plant introns contain neither conserved branch points nor distinct 3' splice site-proximal polypyrimidine tracts characteristic of the yeast and vertebrate introns, respectively. However, they are strongly enriched in U residues throughout the intron, property essential for splicing. To understand the roles of different sequence elements in splicing, we are characterizing proteins involved in intron recognition in plants. In this work we show that Nicotiana plumbaginifolia, a dicotyledonous plant, contains two genes encoding different homologs of the large 50-65-kDa subunit of the polypyrimidine tract binding factor U2AF, characterized previously in animals and Schizosaccharomyces pombe. Both plant U2AF65 isoforms, referred to as NpU2AF65a and NpU2AF65b, support splicing of an adenovirus pre-mRNA in HeLa cell nuclear extracts depleted of the endogenous U2AF factor. Both proteins interact with RNA fragments containing plant introns and show affinity for poly(U) and, to a lesser extend, poly(C) and poly(G). The branch point or the 3' splice site regions do not contribute significantly to intron recognition by NpU2AF65. The existence of multiple isoforms of U2AF may be quite general in plants because two genes expressing U2AF65 have been identified in Arabidopsis, and different isoforms of the U2AF small subunit are expressed in rice.     

A XANES study of the valence state of vanadium in lithium vanadate phosphate glasses

Valence states of vanadium in Li₂O-V₂O₅-P₂O₅ electronic-ionic conducting glasses have been studied by X-ray absorption spectroscopy. The composition dependence of the XANES range of the spectra has been used to estimate relative abundance of the vanadium atoms in V⁴⁺ or V⁵⁺ charge states. This information is important for analysis of electronic transport in these glasses, which occurs via electronic hopping between aliovalent vanadium centers. It was found that in samples with the lowest V₂O₅ contents (10 mole% of V₂O₅) a vast majority of vanadium ions are in V⁴⁺ charge state. At higher V₂O₅ contents the proportion of V⁴⁺ ions decreases at the expense of V⁵⁺ ones, but remains substantial even in glasses with the highest contents of V₂O₅.     

Understanding emotional transitions: The interpersonal consequences of changing emotions in negotiations.

Research on the interpersonal functions of emotions has focused primarily on steady-state emotion rather than on emotional transitions, the movement between emotion states. The authors examined the influence of emotional transitions on social interactions and found that emotional transitions led to consistently different outcomes than their corresponding steady-state emotions. Across 2 computer-mediated negotiations and a face-to-face negotiation, participants negotiating with partners who displayed a “becoming angry” (happy to angry) emotional transition accepted worse negotiation outcomes yet formed better relational impressions of their partners than participants negotiating with partners who displayed steady-state anger. This relationship was mediated through 2 mechanisms: attributional and emotional contagion processes. The “becoming happy” (angry to happy) emotional transition as compared with steady-state happiness was not significantly related to differences in negotiation outcomes but was significantly related to differences in relational impressions, where perceivers of the “becoming happy” emotional transition gave their partners lower relational impression ratings than perceivers of steady-state happiness. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Removal of 5'-terminal m7G from eukaryotic mRNAs by potato nucleotide pyrophosphatase and its effect on translation

The procedure for isolation of nucleotide pyrophosphatase (E.C. 3.6.1.9.) from potato has been modified to yield an endonuclease-free preparation purified 2300-fold. The enzyme was used for specific cleavage of pyrophosphate linkages in the 5'-terminal cap (m7GpppN) of several eukaryotic messenger RNAs. Enzymatic removal of 5'-terminal pm7G from reovirus, rabbit globin and Artemia salina mRNAs resulted in an almost complete loss (greater than 80%) of their template activities in a cell-free protein synthesizing system from wheat germ. Incubation with nucleotide pyrophosphatase did not decrease the translation of phage f2 RNA in an Escherichia coli cell-free system.