Unusual chemical composition of a Mexican propolis collected in Quintana Roo, Mexico

Propolis is a resinous natural substance collected by honeybees from buds and exudates of various trees and plants; it is widely accepted that the composition of propolis depends on the phytogeographic characteristics of the site of collection. In this study we have analyzed the chemical composition of a propolis collected in Quintana Roo, Mexico, and evaluated its antioxidant, antifungal and antibacterial activities. Unexpectedly, the chemical analysis showed that the main components of the ethanolic extract of a Mexican propolis appeared to be pentacyclic triterpenoids, such as α and β-amyrin derivatives, and sterols. The crude extract did not show antioxidant activity when tested using the DPPH-reduction assay, and it also proved inactive when tested for antifungal and antibacterial activities using microdilution and agar diffusion assays, respectively. The fact that the presence of both α and β-amyrins and their derivatives have been reported from the resin of Bursera simaruba, one of the plants used by the bees for propolis production in Quintana Roo, Mexico, confirms the relationship that exists between the flora available to bees in a given region and the chemical composition of the propolis that they produce

Unusual chemical composition of a Mexican propolis collected in Quitana Roo, Mexico

Propolis, or bee glue, is a natural resinous hive product collected by honeybees from buds and exudates of various trees and plants. Mixed with beewax and salivary enzymes, it is used to fill in cracks and holes in the hive as well as a chemical weapon against intruders. It is well known that the chemical composition of propolis depends on the flora at the site of collection. The aim of this study was to compare two different propolis batches. The first one collected in France (south-west) and the second one in Quintana Roo, Mexico. The ethanolic extract of the French propolis (EEP) contained mainly polyphenols such as phenolic acids and their esters and flavonoids (poplar type), while the same kind of extract from the Mexican propolis showed only triterpenoids such as α and β-amyrin derivatives. Although the latter composition is quite unusual for a Mexican propolis, α and β-amyrins -and their derivatives- have been reported to occur in the resin of Bursera simaruba,1 a tree that grows in Quintana Roo. Both propolis were evaluated in terms of their biological activity, including antioxidant (DPPH), anti-AGEs, antifungal (Candida albicans and Aspergillus fumigatus), and antibacterial (21 Gram-positive and Gram-negative strains including Staphyloccocus aureus). Whereas French EEP exhibited high antioxidant and anti-AGEs activities,2 as well as very good antifungal (towards C. albicans) and antibacterial (towards S. aureus) activities, Mexican EEP proved to be inactive. These results suggest that the chemical composition of the propolis collected in Quintana Roo is qualitatively and quantitatively of particular importance in the ecological interaction between the bees and the parasites and microorganisms that occur specifically in that region

Unusual chemical composition of a Mexican Propolis collected in Yucatan

Introduction: Propolis, or bee glue, is a natural resinous hive product collected by honeybees from buds and exudates of various trees and plants. Mixed with beewax and salivary enzymes, it is employed to fill cracks and embalm dead invaders in the hive. Several studies about mexican propolis have revealed chemical profiles where cinnamic and phenylpropanoic acid derivatives as well as flavonoids dominated, whereas these extracts exhibited cytotoxic and/or antifungal activities. Research methods: An ethanolic extract of a batch of mexican propolis, collected in the state of Quintana Roo, Mexico, was first analysed by High Performance Liquid Chromatography coupled with Diode Array Detector (HPLC/DAD) but no major components could be detected. Its antioxidant activity was evaluated by 1,1-diPhenyl-2-PicrylHydrazyl (DPPH) assay as well, and its antibacterial (against 21 Gram-positive and Gram-negative strains including Staphyloccocus aureus) and antifungal (against Candida albicans and Aspergillus fumigatus) properties were evaluated through microdilution assays. Then, this extract was fractionated by Flash chromatography. Three of the fractions, containing the major constituents, were analysed by Gas Chromatography coupled with Mass Spectrometry (GC/MS). Results and discussion: This Mexican propolis did not show any antioxidant neither antibacterial nor antifungal activity. The main constituents of this Mexican propolis were identified as triterpenes (amyrenone, amyrin and amyrin-3-acetate) and sterols (fucosterol and sistosterol). This unusual composition associated with a Mexican propolis would thus explain the lack of biological activities. Further investigations will be conducted in order to link this chemical composition with the propolis plant sources

Robot-Assisted Inspection of Concrete Box Girders in Bridges

This paper describes a robotic solution to the structural health inspection of concrete box girders. A combination of sensors including a laser range finder, a depth (RGB-D) camera, an inertial measurement unit and a high-resolution camera are mounted on a tracked robot. The robot can be driven inside a box girder even when there are steps present, to collect high-resolution images of the concrete structure. Software that allows the information captured to be registered with a 3D geometric map of the inside of a box girder, and a visualization tool that can be used to evaluate location-annotated highly-detailed surface condition pictures by the human operator has been developed. The proposed remote evaluation technique makes it feasible to safely monitor areas over a sequence of inspections, leading to more effective maintenance procedures. The effectiveness of the system is illustrated using data gathered during a field trial where the robot was deployed within the Overpass at Huntleyâs Point, in the junction between Victoria Road and Burns Bay Road in Sydney. Functionality to automatically identify defects/regions of interest is also being investigated. It is anticipated that supplementing manual inspection tasks with robotic aids will mitigate the risk to manual entry into a confined space with a consequential saving in associated cost. This project is collaboration between the University of Technology Sydney (UTS) and the Roads & Traffic Authority (RTA) of NSW

Influence des déformations de pales sur l'aérodynamique et l'aéroacoustique haute vitesse et basse vitesse des doublets d'hélices contrarotatives

International audienceThis paper investigates by means of computational fluid dynamics (CFD) and acoustic analogy the influence of blade deformations on open-rotor aerodynamics and aeroacoustics for three key operating points: cruise, takeoff, and approach conditions. For each operating point, simulation results obtained with unrunning blade shapes and running blade shapes are compared with wind tunnel test measurements. Experiments show that blade deformations affect mostly the front rotor, with twist deviations at tip varying within a range of ±2  deg and of opposite sign between cruise and takeoff conditions. Although blade deformations are low for the rear rotor, aerodynamic performance exhibits significant variations due to the modifications of the front rotor wash. Numerical results show that accounting for blade deformations increases or decreases the thrust or power depending on the operating point and leads to a much better prediction of the open-rotor aerodynamic performance. The same comments apply for the noise prediction although differences on self-noise and interaction noise directivities are rather low.Cet article étudie par simulation numérique influence des déformations de pale sur l'aérodynamique et l'aéroacoustique d'un doublet d'hélices contrarotatives pour trois points de fonctionnement différents: conditions de croisière, de décollage et d'approche. Pour chaque point de fonctionnement, les résultats des simulations obtenus avec des formes de pales à froid et à chaud sont comparés aux mesures effectuées sur la configuration générique Open-Rotor AI-PX7 d'Airbus Clean Sky dans la soufflerie transsonique S1MA de l'ONERA