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An experimental study of hafting adhesives and the implications for compound tool technology.

ABSTRACT: Experimental studies of hafting adhesives and modifications to compound tool components can demonstrate the extent to which human ancestors understood and exploited material properties only formally defined by science within the last century. Discoveries of Stone Age hafting adhesives at archaeological sites in Europe, the Middle East, and Africa have spurred experiments that sought to replicate or create models of such adhesives. Most of these studies, however, have been actualistic in design, focusing on replicating ancient applications of adhesive technology. In contrast, this study tested several glues based on Acacia resin within a materials science framework to better understand the effect of each adhesive ingredient on compound tool durability. Using an overlap joint as a model for a compound tool, adhesives formulated with loading agents from a range of particle sizes and mineral compositions were tested for toughness on smooth and rough substrates. Our results indicated that overlap joint toughness is significantly increased by using a roughened joint surface. Contrary to some previous studies, there was no evidence that particle size diversity in a loading agent improved adhesive effectiveness. Generally, glues containing quartz or ochre loading agents in the silt and clay-sized particle class yielded the toughest overlap joints, with the effect of particle size found to be more significant for rough rather than smooth substrate joints. Additionally, no particular ochre mineral or mineral mixture was found to be a clearly superior loading agent. These two points taken together suggest that Paleolithic use of ochre-loaded adhesives and the criteria used to select ochres for this purpose may have been mediated by visual and symbolic considerations rather than purely functional concerns.

SUBMITTER: Zipkin AM

PROVIDER: S-EPMC4226580 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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An experimental study of hafting adhesives and the implications for compound tool technology.

Zipkin Andrew M AM Wagner Mark M McGrath Kate K Brooks Alison S AS Lucas Peter W PW

PloS one 20141110 11

Experimental studies of hafting adhesives and modifications to compound tool components can demonstrate the extent to which human ancestors understood and exploited material properties only formally defined by science within the last century. Discoveries of Stone Age hafting adhesives at archaeological sites in Europe, the Middle East, and Africa have spurred experiments that sought to replicate or create models of such adhesives. Most of these studies, however, have been actualistic in design, ...[more]

PMID: 25383871

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Project description:OBJECTIVES:This proof-of-principle, single-center, randomized, examiner-blind, crossover study compared two experimental polyvinyl acetate (PVA)-based denture adhesives (Test Adhesives 1 and 2) with a marketed reference polymethyl vinyl ether/maleic anhydride (PMV/MA)-based adhesive and no adhesive using incisal bite force area over baseline over 12 hr (AOB0-12 ) in participants with an at least moderately well-fitting complete maxillary denture. Previous in vitro studies suggested the experimental denture adhesives provided superior performance. MATERIALS AND METHODS:Participants were randomized to a treatment sequence such that each received each treatment once. Prior to treatment application (baseline) and at 0.5, 1, 3, 6, 9, and 12 hr following the application, participants bit on a force transducer until their maxillary denture dislodged. Between-treatment differences in AOB0-12 were analyzed using analysis of covariance. For study validity, the reference adhesive was compared with no adhesive. Participants were asked to rate sensory experiences and ease of denture removal. RESULTS:Twenty-three participants were included in the modified intent-to-treat population. Although Test Adhesives 1 and 2 had a higher mean AOB0-12 than no adhesive, differences were not statistically significant. No statistically significant difference was also found between the reference adhesive and no adhesive; hence, study validity was not attained. Participants did not report any clear differences between the test or reference adhesives in terms of taste or feel; however, dentures were easier to remove with the test adhesives versus reference. No treatment-related adverse events were reported. CONCLUSION:Neither the experimental PVA-based denture adhesives nor the PMV/MA-based reference product demonstrated a statistically significant difference in incisal bite force AOB0-12 compared with no adhesive. The reasons for these unexpected results is unclear; they suggest that findings of in vitro tests for denture adhesive performance are not always translated to in vivo performance (Clinicaltrials.gov: NCT02937870).

Project description:BackgroundNowadays, a number of mechanisms and tools are being used by health care organizations and physicians to electronically exchange the personal health information of patients. The main objectives of different methods of health information exchange (HIE) are to reduce health care costs, minimize medical errors, and improve the coordination of interorganizational information exchange across health care entities. The main challenges associated with the common HIE systems are privacy concerns, security risks, low visibility of system transparency, and lack of patient control. Blockchain technology is likely to disrupt the current information exchange models utilized in the health care industry.ObjectiveLittle is known about patients' perceptions and attitudes toward the implementation of blockchain-enabled HIE networks, and it is still not clear if patients (as one of the main HIE stakeholders) are likely to opt in to the applications of this technology in HIE initiatives. Thus, this study aimed at exploring the core value of blockchain technology in the health care industry from health care consumers' views.MethodsTo recognize the potential applications of blockchain technology in health care practices, we designed 16 information exchange scenarios for controlled Web-based experiments. Overall, 2013 respondents participated in 16 Web-based experiments. Each experiment described an information exchange condition characterized by 4 exchange mechanisms (ie, direct, lookup, patient-centered, and blockchain), 2 types of health information (ie, sensitive vs nonsensitive), and 2 types of privacy policy (weak vs strong).ResultsThe findings show that there are significant differences in patients' perceptions of various exchange mechanisms with regard to patient privacy concern, trust in competency and integrity, opt-in intention, and willingness to share information. Interestingly, participants hold a favorable attitude toward the implementation of blockchain-based exchange mechanisms for privacy protection, coordination, and information exchange purposes. This study proposed the potentials and limitations of a blockchain-based attempt in the HIE context.ConclusionsThe results of this research should be of interest to both academics and practitioners. The findings propose potential limitations of a blockchain-based HIE that should be addressed by health care organizations to exchange personal health information in a secure and private manner. This study can contribute to the research in the blockchain area and enrich the literature on the use of blockchain in HIE efforts. Practitioners can also identify how to leverage the benefit of blockchain to promote HIE initiatives nationwide.

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An experimental study of hafting adhesives and the implications for compound tool technology.

Publications

An experimental study of hafting adhesives and the implications for compound tool technology.

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