Search results for " Humidity"
showing 10 items of 178 documents
Water transport in epoxy/MWCNT composites
2013
Moisture and water uptake of epoxy/multi-wall carbon nanotube (MWCNT) composites was studied in a wide range of atmosphere relative humidity and temperatures. Addition of up to 1 wt.% of MWCNTs into the neat epoxy resulted to the twofold decrease of the diffusivity, while the levels of moisture/water uptake remained unchanged. The positive effect on the reduction of the diffusion coefficient diminishes with the increase of temperature. Differences in the water transport properties and plasticization ability of the neat polymer and its nanocomposites are explained by the free volume considerations and the polymer–water interactions, which are verified by the results of thermomechanical analy…
A new approach to studying sponge cake aroma after storage in treated paper and plastic packaging by direct gas chromatography–olfactometry (D-GC–O)
2007
The objective of this study was to use D-GC–O to compare the global odour of a sponge cake flavoured with either a ‘viennoiserie’ aromatic note or a simplified mixture of aroma compounds (used for physicochemical studies), then stored in a glass packaging (inert and impermeable) or in pouches made with treated papers or with plastic packaging, in accelerated ageing conditions (high temperature and relative humidity gradient). After 1 week of storage, the flavoured sponge cake headspace was SPME-extracted directly into the packaging and analysed by D-GC–O. The sponge cake global odour was better retained if plastic film rather than treated-papers was used, for both flavourings. Changes in th…
Three-Dimensional Microstructural Properties of Nanofibrillated Cellulose Films
2014
Abstract: Nanofibrillated cellulose (NFC) films have potential as oxygen barriers for, e.g., food packaging applications, but their use is limited by their hygroscopic characteristics. The three-dimensional microstructure of NFC films made of Pinus radiata (Radiata Pine) kraft pulp fibres has been assessed in this study, considering the structural development as a function of relative humidity (RH). The surface roughness, micro-porosity, thickness and their correlations were analyzed using X-ray microtomography (X–μCT) and computerized image analysis. The results are compared to those from scanning electron microscopy and laser profilometry. Based on a series of films having varying amounts…
Littoral Dunes on Valencia Coast
2018
The dunes development needs an excess of sediment supply, wind speed able to transport sand to backshore and low atmospheric humidity. Foredunes, dunes fields and Pleistocene fossil dunes are the most characteristics features of the Valencian coast. Fossil dunes are abundant at the southern part. They are the main supply for the Holocene dunes and formed l’Altet field that survived thanks to be just in front of the L’Altet Airport. The foredunes have been mainly destroyed by human action and only few remains still are active. Guardamar and El Saler dune fields had a quite different evolution. Guardamar evolved covering previous fossil dunes and was fixed with pine trees to avoid the sand pr…
Bactrocera oleae. Fattori naturali di controllo
2019
Bactrocera oleae. Natural control factors. Natural control factors (parasitoids and climatic factors) influencing the olive fruit fly, Bactrocera oleae, are analysed comparing two different areas of cultivated and wild olives, Sicily and the Western Cape of South Africa. Bactrocera oleae has a similar level of parasitization in both areas, much higher in wild olives than in cultivated ones. Climatic conditions are much more important than climatic factors, influencing the growth of olive fruit fly populations, producing a higher level of infestation in more humid and rainy productive seasons.
Humidity effect on ammonia sensing properties of substituted and unsubstituted cobalt phthalocyanines
2012
In this paper, we studied the effect of humidity on the response of cobalt phthalocyanine-containing resistors to ammonia, in the ppm range. We pointed out the fact that, when alternating exposure periods with recovery periods, the humidity effect had to be carefully studied, in correlation with the flow variation. Thus, for a sulfonated cobalt phthalocyanine, the effect of NH(3) was totally screened as soon as the relative humidity (RH) was above 10%. On the contrary, when using unsubstituted cobalt phthalocyanine (CoPc) as sensing material, the sensors' response to NH(3) appears to be quite stable in a wide RH range, allowing a discrimination between 12, 25 and 50 ppm of NH(3) over the 10…
Impact of relative air humidity fluctuations on the survival of Listeria monocytogenes : application to improve hygiene in food processing environment
2016
Environmental hydration fluctuations influence microorganism viability and activity. The air relative humidity (RH) is a potentially effective parameter to control the development and the persistence of pathogenic microorganisms. However, efficiency of this parameter remains not well characterized compared to others environmental factors such as pH or temperature. Drying is the final step of cleaning and disinfection processes used in the food industry. However, if this process is empirically used, it could also be used to improve the decontamination of surfaces in premises and reduce the persistence of microorganisms. Despite cleaning and disinfection, Listeria monocytogenes is commonly fo…
High-Resolution Fluorescence Spectra of Airborne Biogenic Secondary Organic Aerosols: Comparisons to Primary Biological Aerosol Particles and Implica…
2021
Aqueous extracts of biogenic secondary organic aerosols (BSOAs) have been found to exhibit fluorescence that may interfere with the laser/light-induced fluorescence (LIF) detection of primary biological aerosol particles (PBAPs). In this study, we quantified the interference of BSOAs to PBAPs by directly measuring airborne BSOA particles, rather than aqueous extracts. BSOAs were generated by the reaction of d-limonene (LIM) or α-pinene (PIN) and ozone (O3) with or without ammonia in a chamber under controlled conditions. With an excitation wavelength of 355 nm, BSOAs exhibited peak emissions at 464–475 nm, while fungal spores exhibited peak emissions at 460–483 nm; the fluorescence intensit…
Field Raman analysis to diagnose the conservation state of excavated walls and wall paintings in the archaeological site of Pompeii (Italy)
2012
This work presents the results of field Raman analyses, assisted by a hand-held energy dispersive-X-ray fluorescence spectrometer, to experimentally determine the composition of compounds present in the walls and wall paintings of two Pompeian houses, one with many luxurious decorative elements (the House of Marcus Lucretius, Regio IX, Insula 3, House 5/24) and a more modest building (Regio IX, Insula 3, House 1–2). These houses were excavated 150 years ago, and the majority of the rooms have been exposed outdoors. The chemical attacks of the acid gases and the biological colonisation can be considered the most serious problems of the archaeological remains from Insula IX 3 of Pompeii. The …
Organic solvents vapor pressure and relative humidity effects on the phase transition rate of α and β forms of tegafur.
2011
The objective of this work was to investigate the relative humidity (RH) and solvent vapor pressure effects on the phase transition dynamics between tegafur polymorphic forms that do not form hydrates and solvates. The commercially available α and β modifications of 5-fluoro-1-(tetrahydro-2-furyl)-uracil, known as the antitumor agent tegafur, were used as model materials for this study. While investigating the phase transitions of α and β tegafur under various partial pressures of methanol, n-propanol, n-butanol, and water vapor, it was determined that the phase transition rate increased in the presence of solvent vapors, even though no solvates were formed. By increasing the relative air h…