scholarly journals The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

Lubricants ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 23 ◽  
Author(s):  
Adam Rylski ◽  
Krzysztof Siczek

The aim of the paper was to discuss different effects, such as, among others, agglomeration of selected nanoparticles, particularly those from zirconia, on the tribological behavior of lubricants. The explanation of the difference between the concepts of ‘aggregation’ and ‘agglomeration’ for ZrO2 nanoparticles is included. The factors that influence such an agglomeration are considered. Classification and thickeners of grease, the role of additives therein, and characteristics of the lithium grease with and without ZrO2 additive are discussed in the paper. The role of nanoparticles, including those from ZrO2 utilized as additives to lubricants, particularly to the lithium grease, is also discussed. The methods of preparation of ZrO2 nanoparticles are described in the paper. The agglomeration of ZrO2 nanoparticles and methods to prevent it and the lubrication mechanism of the lithium nanogrease and its tribological evaluation are also discussed. Sample preparation and a ball-on disc tester for investigating of spinning friction are described. The effect of ZrO2 nanoparticles agglomeration on the frictional properties of the lithium grease is shown. The addition of 1 wt.% ZrO2 nanoparticles to pure lithium grease can decrease the friction coefficient to 50%. On the other hand, the agglomeration of ZrO2 nanoparticles in the lithium grease can increase twice the friction coefficient relative to that for the pure grease.

2018 ◽  
Vol 6 (4) ◽  
pp. 401-428
Author(s):  
Miriam R. Lowi

Studies of identity and belonging in Gulf monarchies tend to privilege tribal or religious affiliation, if not the protective role of the ruler as paterfamilias. I focus instead on the ubiquitous foreigner and explore ways in which s/he contributes to the definition of national community in contemporary gcc states. Building upon and moving beyond the scholarly literature on imported labor in the Gulf, I suggest that the different ‘categories’ of foreigners impact identity and the consolidation of a community of privilege, in keeping with the national project of ruling families. Furthermore, I argue that the ‘European,’ the non-gcc Arab, and the predominantly Asian (and increasingly African) laborer play similar, but also distinct roles in the delineation of national community: while they are differentially incorporated in ways that protect the ‘nation’ and appease the citizen-subject, varying degrees of marginality reflect Gulf society’s perceptions or aspirations of the difference between itself and ‘the other(s).’


2019 ◽  
Vol 16 (2) ◽  
pp. 219-238
Author(s):  
Nikos Vergis

AbstractDoes having a communicative role other than the speaker’s make a difference to the way pragmatic meaning is construed? Standard paradigms in interpersonal pragmatics have implicitly assumed a speaker-centric perspective over the years, however modern approaches have re-considered the role of listener evaluations. In the present study, I examine whether assuming different communicative roles (speaker, listener, observer) results in varying interpretations. A web-based experiment revealed that participants who took the perspective of different characters in short stories differed in the way they interpreted what the speaker meant. In most cases, participants in the role of the listener interpreted speaker meaning in more negative ways than participants in the other roles. The present study suggests that the directionality of the difference (negative inferences under the listener’s perspective) could be explained by taking into account affective factors.


1975 ◽  
Author(s):  
B. M. Bas ◽  
A. D. Muller ◽  
H. G. Hemker

Five different ways of estimating prothrombin are applied to the plasma of persons receiving vitamin K antagonists, to know: the one-stage assay, the two-stage assay, the Echis Carinatus Venom assay, the coagulase-reacting factor assay and the immunological assay. The Protein Induced by Vitamin K Absence analogous to prothrombin (PIVKA-II) can be shown to be co-estimated in all but the one-stage assay. There are minor differences, however, between the other four tests. The most practical way to assess both prothrombin and PIVKA-II seems to be the coagulase-reacting factor assay. The difference between the one-stage assay and the others can be explained on basis of the new data on the role of vitamin K in prothrombin biosynthesis. The differences between the other tests are smaller and remain to be explained.


2011 ◽  
Vol 366 (1581) ◽  
pp. 3106-3114 ◽  
Author(s):  
Astrid M. L. Kappers

In this paper, I focus on the role of active touch in three aspects of shape perception and discrimination studies. First an overview is given of curvature discrimination experiments. The most prominent result is that first-order stimulus information (that is, the difference in attitude or slope over the stimulus) is the dominant factor determining the curvature threshold. Secondly, I compare touch under bimanual and two-finger performance with unimanual and one-finger performance. Consistently, bimanual or two-finger performance turned out to be worse. The most likely explanation for the former finding is that a loss of accuracy during intermanual comparisons is owing to interhemispheric relay. Thirdly, I address the presence of strong after-effects after just briefly touching a shape. These after-effects have been measured and studied in various conditions (such as, static, dynamic, transfer to other hand or finger). Combination of the results of these studies leads to the insight that there are possibly different classes of after-effect: a strong after-effect, caused by immediate contact with the stimulus, that does only partially transfer to the other hand, and one much less strong after-effect, caused by moving over the stimulus for a certain period, which shows a full transfer to other fingers.


1952 ◽  
Vol 4 (1) ◽  
pp. 27-45 ◽  
Author(s):  
James A. Dinsmoor

Twelve white rats learned to press a bar or lever when this act was intermittently followed by pellets of food. Once a stable rate of pressing had been established, the animals were subjected to electric shock as a punishment for each response during alternate five minute periods within the experimental session. A difference in rates during the safe and punished phases was manifested both by the experimental group (8 rats), who were provided with a light as a signal when it was safe to respond, and also, contrary to expectation, by the control group (4 rats), who continued in darkness throughout the session. The differential responding by the control group was greatly reduced, however, when the duration of each phase was reduced from five minutes to one. The investigation was then continued to determine the role of some of the other factors in the situation. Increasing the severity of the shock increased the difference between the light and the dark rates. Withholding the pellets of food reduced the overall rates but did not affect the light-dark discrimination. Withholding the shock, on the other hand, permitted an increase in rate and caused the animals to lose their discrimination; when food had previously been withheld, however, so that the rate of response was relatively low, this deterioration in the discrimination was not as rapid as before. Restoration of the discrimination training under a lower hunger drive confirmed the finding that the formation of the discrimination was quite rapid and showed that the level of drive did not affect the proportionality between the rates in the light and in the darkness. These findings were interpreted by comparing the current procedure with those previously used in studies of avoidance reactions and conflict.


1939 ◽  
Vol 39 (3) ◽  
pp. 298-310 ◽  
Author(s):  
A. Beck

1. The examination of 1100 sera by both the Wassermann reaction and the complement-fixation test with spirochaetes revealed a superior sensitivity of the latter reaction and practically equal specificity of the two tests.2. Syphilitic serum contains two different antibodies: one reacting with the lipoid antigen of the Wassermann reaction, the other with a specific antigen in the spirochaete.3. The spirochaetal antibody of syphilitic serum has a complex serological structure, corresponding to spirochaete strains of different antigenic make-up.4. The existence of this antibody and its specific absorption by the homologous antigen can also be demonstrated by agglutination.5. The difference between agglutinin titres found in normal and syphilitic sera is not pronounced enough to render this method satisfactory for the practical diagnosis of syphilis.6. The spirochaete contains, apart from its specific antigen, the ubiquitous lipoid substance representing the Wassermann antigen.7. A fraction was obtained from spirochaetes by Raistrick and Topley's method which in complement-fixation and precipitation tests reacted actively with spirochaete antisera from rabbits, but which so far failed to react with syphilitic sera.This work was carried out with the aid of a grant from the Rockefeller Foundation. I wish to thank Prof. Golla, Director of the Central Pathological Laboratory, L.C.C. Mental Hospitals, who rendered this work possible, and Dr Arthur Davies, Director of the Devonport Laboratory, for the hospitality afforded me at his laboratory and for the patients’ sera used in this work. I am indebted to Prof. R. T. Hewlett for his revision of the manuscript, to Prof. Raistrick for advice in chemical matters, and to Dr Amies, of the Lister Institute, for his help with the Sharples centrifuge.


2021 ◽  
Vol 30 ◽  
pp. 654
Author(s):  
Morwenna Hoeks

Disjunctive questions are ambiguous: they can either be interpreted as polar questions (PolQs), as open disjunctive questions (OpenQs), or as closed alternative questions (ClosedQ). The goal of this paper is to show that the difference in interpretation between these questions can be derived via effects of focus marking directly. In doing so, the proposal brings out the striking parallel between the prosody of questions with foci/contrastive topics on the one hand and that of alternative questions on the other. Unlike previous approaches, this proposal does not rely on structural differences between AltQs and PolQs derived via ellipsis or syntactic movement. To show how this works out, an account of focus and contrastive topic marking in questions is put forward in which f-marking in questions determines what constitutes a possible answer by signaling what the speaker's QUD is like. By imposing a congruence condition between f-marked questions and their answers that requires answers to resolve the question itself as well as its signaled QUD, we predict the right answerhood conditions for disjunctive questions.


2018 ◽  
pp. 174-190
Author(s):  
Piotr Sobolczyk

The paper revises the biographical data about Michel Foucault’s stay in Poland in 1958-1959. The main inspiration comes from the recent very well documented literary reportage book by Remigiusz Ryziński, Foucault in Warsaw. Ryziński’s aim is to present the data and tell the story, not to analyse the data within the context of Foucault’s work. This paper fulfills this demand by giving additional hypotheses as to why Polish authorities expelled Foucault from Poland and what the relation was between communism and homosexuality. The Polish experience, the paper compels, might have been inspiring for many of Foucault’s ideas in his Madness and Civilization, Discipline and Punish, and The History of Sexuality. On the other hand the author points to the fact that Foucault recognized the difference between the role of the intellectual in the West and in communist countries but did not elaborate on it. In this paper the main argument deals with the idea of sexual paranoia as decisive, which is missing in Foucault's works, although it is found in e.g. Guy Hocquenghem.


1991 ◽  
Vol 14 (1) ◽  
pp. 3-16
Author(s):  
Paul Paridaen

Abstract This paper analyzes the role of language in the perception of violence in television news stories. 240 people were asked to watch and/or listen to news stories and then to record their perception of the information. The difference between perceived violence from pictures only on the one hand, and spoken narrative with or without pictures on the other, was highly significant, indicating that the spoken narrative was responsible for the perception of violence in the stories.


2011 ◽  
Vol 25 (31) ◽  
pp. 4261-4264 ◽  
Author(s):  
MANABU YASUOKA

A hard film coat can improve a tool's performance. In this study, the frictional properties of an uncoated tool and a coated tool with TiN were measured against that of SCM440 (42 CrMo 4) steel. The results showed there was no significant difference between the friction coefficient of the high-speed steel tool and the tool coated with TiN but the friction coefficient of uncoated tool was slightly lower than that of the steel. In the second part of the study, coats of TiN , TiC , CrN , and TiAlN were deposited on high-speed steel and the wear characteristics were determined with a pin-on-disk wear examination. The differences in the friction coefficients were attributed to the difference in the wear of the slipping material. There were large differences in the adhesion characteristics on the surface of the slipping material. The author suggest that these differences influence the characteristics of the cutting tool.


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