Search results for "medium"
showing 10 items of 3746 documents
<title>Using infrared thermography as a tool to analyze curling and cockling of paper</title>
1992
Paper surface topology analysis with infrared thermography is described. Heat is applied perpendicular to the target. Temperature distribution of the sheet correlates well with the surface height distribution when the sheet is placed on the isothermic plate. Mathematical tools for data analysis and the mechanisms behind the curl and cockles are briefly discussed. Curl in paper and paperboard is defined as deviation from the flat form.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
UV-C as an Efficient Means to Combat Biofilm Formation in Cultural Heritage Monument. Biodiversity and Impact on Prehistoric Pigments?
2018
Caves are considered oligotrophic habitats exhibiting constant temperature and relative humidity throughout the year. While darkness inhibits photosynthetic microorganism growth, introducing artificial lights to promote touristic activity can induce algae and cyanobacteria proliferation. Besides the aesthetic problem, microorganisms are responsible of physical and chemical degradation of limestone wall with possibly a degradation of prehistoric painting of cultural value. In our studies, we identified lampenflora with new-generation sequencing (NGS) in five French show caves and also on a 180, 000 years old contaminated bear bones (Ursus deningeroides). Afterward, we attempted to find an ec…
A Portable Dynamic Laser Speckle System for Sensing Long-Term Changes Caused by Treatments in Painting Conservation
2018
[EN] Dynamic laser speckle (DLS) is used as a reliable sensor of activity for all types of materials. Traditional applications are based on high-rate captures (usually greater than 10 frames-per-second, fps). Even for drying processes in conservation treatments, where there is a high level of activity in the first moments after the application and slower activity after some minutes or hours, the process is based on the acquisition of images at a time rate that is the same in moments of high and low activity. In this work, we present an alternative approach to track the drying process of protective layers and other painting conservation processes that take a long time to reduce their levels …
Bimetallic complexes with ruthenium and tantalocene moieties: Synthesis and use in a catalytic cyclopropanation reaction
2006
Abstract The reaction of the tantalocene dichloride monophosphines ( 1 – 2 ) with the binuclear complex [( p -cymene)RuCl 2 ] 2 gives the heterobimetallic compounds ( p -cymene)[(η 5 -C 5 H 5 )(μ-η 5 :η 1 -C 5 H 4 (CH 2 ) 2 PR 2 )TaCl 2 ]RuCl 2 ( 3 – 4 ). The air oxidation of these bimetallic species 3 – 4 , leads to the cationic hydroxo tantalum ruthenium derivatives 5 – 6 . The last ones are easily deprotonated by a base to afford the oxo analogues 7 – 8 . A preliminary assessment in catalytic cyclopropanation of styrene with tantalum ruthenium bimetallic complexes 3 – 8 as precatalysts revealed a cooperative effect with a subtle role of the early metal fragment.
The Effect of Vanadium on the Content of Chlorophyll, P-700 and Cytochrome f at Different Light Intensities in Chlorella fusca
1980
Summary Cells of Chlorella fusca, were grown in liquid medium supplemented ,vith O.2% glucose and varied concentrations of vanadium both at 5 different light intensities and in the dark. \Vith increasing concentrations of vanadium the content of chlorophyll, P-700 and cytochrome f increased as well, each, however, in a different way. At the saturating concentration of 20 µg vanadium per litre the pigment content per dry weight was double as high as that of the vanadium-free control; the ratio of chlorophyll a/chlorophyll b increased from 2.1 to 2.9. The content of P-700 at saturating vanadium concentration was four times higher than that of the control when based on dry weight and double as…
Ferric-reductase activities in Vibrio vulnificus biotypes 1 and 2.
1999
In this paper, the ferric-reductase activities of Vibrio vulnificus were investigated. This species comprises two biotypes pathogenic for humans and eels that are able to express different mechanisms for iron acquisition. All strains of both biotypes used in this study were able to reduce ferric citrate, irrespective of the iron levels in the growth medium. Some variation in the degree of reduction was observed among the strains, with the highest values corresponding to one acapsulated environmental strain of biotype 1. When cell fractions were tested, only those from periplasm and cytoplasm showed reductase activity whereas no activity was detected in membranes. Low temperatures inhibited …
Isolation and identification of new anthraquinones from Rhamnus alaternus L and evaluation of their free radical scavenging activity
2018
From the butanolic and the ethyl acetate extracts of Rhamnus alaternus L root bark and leaves, three new anthraquinone glycosides, alaternosides A-C (1,4,6,8 tetrahydroxy-3 methyl anthraquinone 1-O-ß-D-glucopyranosyl-4,6-di-O-α-L-rhamnopyranoside (1); 1,2,6,8 tetrahydroxy-3 methyl anthraquinone 8-O-ß-D-glucopyranoside (2) and 1, 6 dihydroxy-3 methyl 6 [2′-Me (heptoxy)] anthraquinone (3)) were isolated and elucidated together with the two known anthraquinone glycosides, Physcion-8-O-rutinoside (4) and emodin-6-O-α-L-rhamnoside (5) as well as with the known kaempferol-7-methylether (6), β-sitosterol (7) and β-sitosterol-3-O-glycoside (8). Their chemical structures were elucidated using spectr…
Integrating fire-scar, charcoal and fungal spore data to study fire events in the boreal forest of northern Europe
2019
Fire is a major disturbance agent in the boreal forest, influencing many current and future ecosystem conditions and services. Surprisingly few studies have attempted to improve the accuracy of fire-event reconstructions even though the estimates of the occurrence of past fires may be biased, influencing the reliability of the models employing those data (e.g. C stock, cycle). This study aimed to demonstrate how three types of fire proxies – fire scars from tree rings, sedimentary charcoal and, for the first time in this context, fungal spores of Neurospora – can be integrated to achieve a better understanding of past fire dynamics. By studying charcoal and Neurospora from sediment cores f…
FRIPON: a worldwide network to track incoming meteoroids
2020
Context. Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile - hence precious - meteorites must be recovered rapidly to avoid their alteration. Aims. The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receiver…
Unprecedented intramolecular pancake bonding in a {Dy2} single-molecule magnet
2020
The first example of unique coordination induced intramolecular pancake bonding was achieved through the reduction of two bis(pyrazolyl)-tetrazine ligands, affording [MIII2(μ-(bpytz)2)(THMD)4](M = Dy, Y; bpytz = 3,6-bis(3,5-dimethyl-pyrazolyl)-1,2,4,5-tetrazine; TMHD = 2,2,6,6-tetramethyl-3,5-heptanedionate). To provide a cohesive magneto-structural correlation, the mono bis(pyrazolyl)-tetrazine bridged congener [DyIII2(μ-bpytz)(THMD)6]·4(C6H6) was also isolated. Both metal complexes exhibit single-molecule magnet behaviour under an applied dc field.