scholarly journals Abutment rotational freedom on five implant systems with different internal connections

Author(s):  
Yvan Bédouin ◽  
Etienne Lefrançois ◽  
Jean-Pierre Salomon ◽  
Pascal Auroy

An attempt has been made to interpret the entropy of adsorption of benzene, toluene and n -heptane on mercury. These investigations have indicated with fair accuracy the amount of translational and rotational freedom possessed by the substances on the surface of mercury. The most striking result was obtained with benzene, where by denying all rotation except in the plane of the ring and denying the third degree of translational freedom, the calculated entropy of adsorption agreed closely with the experimental value. The surface mobility of toluene was found to be considerably hindered, and the entropy of adsorption of n -heptane confirmed the view that the molecules were partially rolled up. An attempt has been made to derive the theoretical heat of adsorption of benzene from various relations for the attractive and repulsive potentials for the van der Waals forces near a metal surface. The values obtained were of the same magnitude as the experimental value. The calculations gave some evidence of the ranges of intermolecular distance over which the different equations for the attractive potential were accurate.


1971 ◽  
Vol 24 (9) ◽  
pp. 1817 ◽  
Author(s):  
DD Deshpande ◽  
LG Bhatgadde

This paper presents the experimental results on the velocity of sound, densities, and heat capacities of eight organic liquids at 25�, 35�, and 45�C. Using Eyring's equation, the free volumes have been calculated from the sound velocity data. For pure liquids, a quantity Cv* = (Cv)L- (Cv)g- Cstr called the residual heat capacity is found to be linearly dependent on free volume. Analysis of the data for 34 liquids shows that a plot of residual heat capacity against the free volume gives a series of straight lines differing in slopes for different groups of liquids such as hydrocarbons, halogen-substituted hydrocarbons, alcohols, etc. This behaviour is ascribed as being due to different degrees of rotational freedom of molecules in these liquids.


2020 ◽  
Vol 17 (6) ◽  
pp. 439
Author(s):  
AzamSadat Mostafavi ◽  
Saied Nokar ◽  
Habib Hajimiragha ◽  
Leyla Sadighpour

Ritið ◽  
2018 ◽  
Vol 18 (2) ◽  
pp. 17-49
Author(s):  
Ástráður Eysteinsson

This essay concerns itself with perceptions of the urban sphere, with its manifestations in literature and life writing, and with the city as a place of strangeness and travel in various senses, including the ways in which it pertains to the individual world view. Cities are places of density and internal connections, but their gates also open out and connect with other places, and increasingly other cities. Following a discussion of the Icelandic links between Copenhagen and Reykjavík, and the slow emergence of the latter as a „literary capital“, the course is set for foreign cities, including Berlin and Paris in the company of Walter Benjamin, and the experience of getting lost with Franz Kafka in places that may be Prague and New York. In attempting to answer the question whether it is possible to become intimate with cities, we have recourse to city guides, life maps, a touring theatre – and the art of losing and finding.


2020 ◽  
pp. 030936462095882
Author(s):  
Cody L McDonald ◽  
Henry Larbi ◽  
Sarah Westcott McCoy ◽  
Deborah Kartin

Background: Information access is essential for quality healthcare provision and education. Despite technological advances, access to prosthetics and orthotics information in low- and middle-income countries is not ubiquitous. The current state of information access, availability, and exchange among prosthetics and orthotics faculty is unknown. Objectives: Describe information exchange networks and access at two prosthetics and orthotics programs in Ghana and the United States. Study design: Cross-sectional survey, social network analysis. Methods: An online survey of faculty at two prosthetics and orthotics programs using REDCap. The survey included a social network analysis, demographics, and prosthetics and orthotics information resources and frequency of use. Descriptive statistics were calculated. Results: Twenty-one faculty members completed the survey (84% response). Ghanaian faculty were on average younger (median Ghana: 27 years, United States: 43 years), had less teaching experience, and had less education than US faculty. Textbooks were the most commonly used resource at both programs. The Ghanaian network had more internal connections with few outside sources. The US network had fewer internal connections, relied heavily upon four key players, and had numerous outside contacts. Conclusion: Ghana and US faculty have two distinct information exchange networks. These networks identify key players and barriers to dissemination among faculty to promote successful knowledge translation of current scientific literature and technology development. Social network analysis may be a useful method to explore information sharing among prosthetics and orthotics faculty, and identify areas for further study.


2014 ◽  
Vol 40 (1) ◽  
pp. 30-34 ◽  
Author(s):  
Simonetta D'Ercole ◽  
Antonio Scarano ◽  
Vittoria Perrotti ◽  
Jorge Mulatinho ◽  
Adriano Piattelli ◽  
...  

Prevention of microbial leakage at the implant-abutment junction is a major challenge for the construction of 2-stage implants in order to minimize inflammatory reactions and to maximize bone stability at the implant neck. The aim of the present in vitro study was an evaluation of the leakage observed over a period of 28 days in Cone Morse taper internal connections and in screwed-abutments connections. In the present study 10 specimens of Cone Morse (Group 1) and 10 of internal hexagon (Group 2) implants were used. The inner parts of 5 implants per group were inoculated with Pseudomonas aeruginosa (PS) suspension and 5 implants per group with Aggregatibacter actinomycetemcomitans (AA). The possible penetration of bacterial suspension into the surrounding solution was determined by the observation of turbidity of the broth. In Group 1, bacterial contamination was found in 3 out of 5 implant-abutment assemblies seeded with the PS and in 2 samples out of 5 in the assemblies seeded with AA, with a total of leaked assemblies in this group of 5 out of 10. In Group 2, bacterial contamination was found in 4 out of 5 implant-abutment assemblies seeded with the PS, and in 4 out of 5 samples seeded with AA, with a total of leaked assemblies of 8 out of 10. The present data confirm the reported high permeability to bacterial leakage of screw-retained abutment connections, and the lower infiltration rates—although not significantly—of Cone Morse taper internal connections.


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