Search results for "resin"
showing 10 items of 385 documents
Chemical composition and antimicrobial activity of some oleogum resin essential oils from Boswellia spp. (Burseraceae)
2007
The chemical composition of Boswellia carteri (Somalia), B. papyrifera (Ethiopia), B. serrata (India) and B. rivae (Ethiopia) oleogum resin essential oils was investigated using GC-MS to identify chemotaxonomy marker components. Total ion current peak areas gave good approximations to relative concentrations based on GCMS peak areas. B. carteri and B. serrata oleogum resin oils showed similar chemical profiles, with isoincensole and isoincensole acetate as the main diterpenic components. Both n-octanol and n-octyl acetate, along with the diterpenic components incensole and incensole acetate, were the characteristic compounds of B. papyrifera oleogum resin oil. Hydrocarbon and oxygenated mon…
Misfit evaluation of dental implant-supported metal frameworks manufactured with different techniques: Photoelastic and strain gauge measurements
2016
This study aims to compare in-vitro the fitting accuracy of implant-supported metal frameworks used for full-arch orthodontic restoration. The hypotheses tested were as follows: (1) for a fixed implant morphology, strains developed within the framework depend on how the framework had been fabricated and (2) stresses transferred to the implant–bone interface are related to the amount of framework misfit. Metal frameworks were fabricated using four different manufacturing techniques: conventional lost-wax casting, resin cement luting, electrospark erosion, and computer-aided design/computer-aided manufacturing milling. Each framework was instrumented with three strain gauges to measure strai…
Development of fast analysis methods for extractives in papermaking process waters
2011
A fast analysis method with an online sample enrichment technique for the analysis of resin and fatty acids present in papermaking process waters was developed. This method was based on atmospheric pressure chemical ionization (APCI) and mass spectrometry (MS) for the detection of [M-H]- ions of compounds of interest. The method was applied to the control of the most prevalent resin (dehydroabietic and abietic) and fatty (palmitic, stearic, oleic, and linolenic) acid levels in papermaking process waters. Continuous data on these acids are of practical importance when predicting possible deposit-derived problems in the paper machine. The first part of the study was focused on the development…
Effects of Polyacrylic Acid Pre-Treatment on Bonded-Dentine Interfaces Created with a Modern Bioactive Resin-Modified Glass Ionomer Cement and Subjec…
2018
Objectives: Resin-modified glass ionomer cements (RMGIC) are considered excellent restorative materials with unique therapeutic and anti-cariogenic activity. However, concerns exist regarding the use of polyacrylic acid as a dentine conditioner as it may influence the bonding performance of RMGIC. The aim of this study was to evaluate the effect of different protocols for cycling mechanical stress on the bond durability and interfacial ultramorphology of a modern RMGIC applied to dentine pre-treated with/without polyacrylic acid conditioner (PAA). Methods: The RMGIC was applied onto human dentine specimens prepared with silicon-carbide (SiC) abrasive paper with or without the use of a PAA c…
A methodology for the control of the residual lifetimes of carbon fibre reinforced composite pressure vessels
2005
International audience; Pressure vessels must be periodically proof tested. Traditional techniques for metal vessels are inapplicable for composite vessels as the latter do not break by crack propagation so that the reasoning behind the traditional testing procedures is not appropriate. Damage accumulation leading to the degradation of a composite vessel is by fibre failure. Fibres show a wide distribution in strengths and loading a composite inevitably breaks some. The method which has been developed is supported by an analysis of delayed fibre failure due to the relaxation of the resin around fibre breaks. This provokes overloading of intact fibres neighbouring breaks. The time until a cr…
La tecnica resinazione del pino laricio (Pinus nigra laricio (Poir.) Maire) in Sicilia: un progetto per la sua rivalutazione nell’ottica di una gesti…
2019
In accordo con le moderne esigenze di sostenibilità e multifunzitonalità, è oggi utile prendere in considerazitone la possibilità di riattivare processi legati ad antichi usi del bosco, la cui memtoria rischia di essere persa per sempre insieme alle tradizioni e ai costumi di comunità nate e sviluppatesi proprio grazie a tali attività. Partendo da tali presupposti, si è condotto uno studio sulla attività di resinazione condotta in Sicilia, a carico del pino laricio, nella pineta di Linguaglossa ricadente nel comune omonimo (prtovincia di Catania) sino agli anni ‘50 del secolo scorso in Sicilia. L’indagine ha inoltre avuto lo scopo di vagliare l’opportunità di ripristinare l’attività resinaz…
Processi di cura di resine epossidiche mediante radiazioni ionizzanti per la realizzazione si materiali compositi per il settore aerospaziale. Influe…
2006
Resistenza alla frattura di quattro materiali per protesi fissa provvisoria: valutazione comparativa in vitro.
2007
Scopo del presente lavoro è stato quello di analizzare la resistenza alla frattura di quattro resine del commercio (Jet Kit, Duralay, Protemp 3 e Systempt C&B), usate per la fabbricazione di protesi parziali provvisorie fisse. Sono stati realizzati venti provini sperimentali di dimensioni standardizzate seguendo le istruzioni dei fabbricanti, suddivisi in quattro gruppi, uno per ciascuno dei quattro materiali testati. Cinque provini di ogni materiale sono stati inseriti in una macchina tipo T.E.M.A, bloccati tra due bracci, uno superiore ed uno inferiore, attraverso un sistema simile a quello di una morsa. La resistenza determinata dai provini sulla trazione esplicata dalla velocità di allo…
Clinical Behavior of Ceramic, Hybrid and Composite Onlays. A Systematic Review and Meta-Analysis
2020
A systematic review and meta-analysis was performed to analyze the survival of onlay restorations in the posterior region, their clinical behavior according to the material used (ceramic reinforced with lithium disilicate, conventional feldspathic ceramic or reinforced with leucite; hybrid materials and composite), possible complications, and the factors influencing restoration success. The systematic review was based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement, without publication date or language restrictions. An electronic search was made in the PubMed, Scopus, Embase, and Cochrane databases. After discarding duplicate publications and stu…
Systematic conformational search analysis of the SRR and RRR epimers of 7-hydroxymatairesinol
2010
An extensive and systematic conformational search was performed on the two epimers of the natural lignan 7-hydroxymatairesinol (HMR), by means of a home-made Systematic Conformational Search Analysis (SCSA) code, designed to select more and more stable conformers through sequential geometry optimization of trial structures at increasing levels of calculation theory. In the present case, the starting molecular structures were selected by the semi-empirical AM1 method and filtered – i.e. decreased in number by choosing the more stable species – on the basis of their energy calculated by the HF method and the 6-31G(d) basis set. The geometries obtained were further refined by performing densit…