Frictional assessment of magnesium stearate and palmitate lubricant powders

A method has been developed for the frictional assessment of powder lubricants using a shear-box tester similar to that employed by Jenike. One commercial magnesium stearate, three high-purity magnesium stearates and three high-purity magnesium palmitates were assessed using this method. Powders with a well-ordered crystal structure and particle shape have a lower initial maximum coefficient of friction μ_a. The difference between μ_a and μ_b, the equilibrium dynamic friction coefficient, gives an indication of lubricant film-forming propensity. The basic friction equation is obeyed by the powders for most of the load range studied but deviates slightly approaching zero normal load.     

Context and lexical access: Implications of nonword interference for lexical ambiguity resolution.

To eliminate potential "backward" priming effects, S. Glucksberg et al (see record 1986-29080-001) introduced a variant of the cross-modal lexical priming task in which subjects made lexical decisions to nonword targets that were modeled on a word related to either the contextually biased or unbiased sense of an ambiguous word. Lexical decisions to nonwords were longer than controls only when the nonword was related to the contextually biased sense of the ambiguous word, leading Glucksberg et al to conclude that context does constrain lexical access and that the multiple access pattern observed in previous studies was probably an artifact of backward priming. We did not find nonword interference when the nonword targets used by Glucksberg et al were preceded by semantically related ambiguous or unambiguous word primes. However, we did replicate their sentence context results when the ambiguous words were removed from the sentences. We conclude that the interference obtained by Glucksberg et al is due to postlexical judgments of the congruence of the sentence context and the target, not to context constraining lexical access. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bizarre imagery, interference, and distinctiveness.

Previous studies have shown that bizarre and common images produce equivalent levels of recall in unmixed-list designs. Using unmixed lists, we tested the view that bizarre images would be less susceptible than common images to common sources of interference. In all experiments, subjects imaged a list of either bizarre or common sentences and then performed some kind of interfering task before recalling the initial list of sentences. Experiment 1 showed that bizarre images were better accessed than common images after imaging an intervening list of common sentences. Also, components of common images tended to be better recalled than those of bizarre images after imaging an intervening list of bizarre sentences. Experiments 2a and 2b showed that interfering tasks consisting of studying lists of common concrete nouns did not differentially affect memory for bizarre and common images. In Experiment 3, labeling and imaging an interfering list of common pictures produced higher recall of bizarre images. Generally, bizarre images appeared to be less susceptible than common images to interference from certain types of common encodings. Importantly, the superior recall of bizarre images was always due to greater image (sentence) access, whereas higher recall of common images was associated with greater recovery of the image (sentence) constituents. Explanation of the precise pattern of results requires consideration of the distinctive properties of bizarre images. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Overview of recent operating experience regarding plant aging

Recent, as well as past, studies of reactor trip frequencies and other types of operating experience have shown that relatively high frequencies are likely in new plants with little accumulated operating time. In order to better understand all the factors which contribute to high frequencies in new plants, the authors have made a comparison of reactor trip frequencies between plants which went into operation in the 1960's and the early 1970's and those which have gone into operation more recently. Trip frequency versus accumulated operating time for two plant groups are compared to see the extent to which design differences (e.g., capacity, thermal margin) affect trip frequency.This paper also presents a review of some recent events in which plant age has played a major role. The events which are reviewed have been identified through the normal systematic event analysis program conducted by the NRC. Information regarding these events was obtained through followup by reviews conducted by NRC Resident Inspectors as well as event reports submitted by licensees.     

Attitudes and beliefs of Canadian infection control decision-makers towards 'borderline' methicillin-resistant Staphylococcus aureus

'Borderline' methicillin-resistant Staphylococcus aureus (MRSA) strains are inhibited by drug concentrations of 2 to 8 micrograms/mL. This type of resistance is usually mediated by 'hyper beta-lactamase' production which is detectable in vitro by susceptibility to combinations of a beta-lactam and a beta-lactamase inhibitor (ie, amoxicillin and clavulanic acid). A survey of Canadian infection control experts was performed to assess the knowledge, attitudes and beliefs regarding the containment requirements for borderline MRSA strains in acute health care facilities. Twenty-three of 38 Canadian infection control experts (61%) (members of the Canadian Hospital Epidemiology Committee [CHEC] or the Society for Healthcare Epidemiology of American [SHEA]) returned a questionnaire about a fictional patient with a postoperative wound infection with such a strain. Eleven respondents (48%) considered the isolate as an MRSA, 11 did not and one was unsure. All who did not believe the strain to be MRSA would not have isolated or cohorted the patient. Four in the latter group would have isolated the patient if he or she were on a neurosurgery or cardiovascular surgery unit, indicating a desire to restrict spread of this isolate on those units. Seven of the 12 individuals who had managed at least one patient with a borderline MRSA did not advocate patient isolation or cohorting, and five did. This survey has supported the belief that there are discrepancies among infection control decision-makers in Canada regarding the approach, precautions and therapy of patients infected with borderline strains of MRSA. Further data on virulence of and effective therapy for these isolates are needed to assess whether the additional cost is warranted in controlling the nosocomial spread of these isolates.     

Addressing the special concerns of landfill closures: VLDPE and textured geomembranes

Landfill closures often require a somewhat different set of properties for synthetic liners than do landfill bottom liner installations. In particular, cap design usually presents the geotechnical engineer with greater concerns regarding long-term slope stability and accommodation of differential settlement. Friction between synthetic liners and materials contacting those liners, multiaxial elongation, and flexibility increase in importance. Since leachate does not contact the liners, chemical resistance becomes less important. Resistance to the components of landfill gas is, in most cases, all that is necessary.

As a result, synthetic liners with a textured surface to improve friction angles, and very low density polyethylene (VLDPE) geomembranes are becoming very attractive to geotechnical engineers. They provide considerable improvement in those areas which are important for cap installation. These materials, however, behave differently in standard index and performance testing of geomembranes, when compared with traditional polyethylene liners. These behaviors and differences are important for geotechnical engineers to understand. They are discussed in this paper.     

On a bounded solution to a pair of coupled nonlinear ordinary differential equations

We present a bounded, decaying solution to a pair of coupled, nonlinear second-order ordinary differential equations arising in the theory of natural convection. The solution is found by transforming the problem into a non-autonomous system in the phase-plane. A uniqueness proof is given for the bounded solution.