Search results for "poros"
showing 10 items of 1076 documents
Investigation of Effective Thermal Conductivity Aluminum Foams
2012
Abstract The study on the heat transfer mechanisms through the aluminium foam with a fluid in void cells of that foam was reported in this paper. Based on laboratory experiments, the effective thermal conductivity coefficient values were found for various type aluminum foams which had been filled up with a gas or a liquid. The significant effects were observed from porosity as well as from metal and fluid properties on the heat transfer capacity in a foam-fluid system. The convective heat transfer phenomenon was identified to occur in the foam cellular space. That phenomenon affected the effective thermal conductivity much more for liquid-filled foams than for gas-filled foams.
Bleach interference in forensic luminol tests on porous surfaces: more about the drying time effect.
2009
As criminals try to avoid leaving clues at the scene of a crime, bloodstains are often washed away, but fortunately for investigators, they are difficult to eliminate completely. Porous surfaces easily retain blood traces, which are sometimes invisible to the naked eye. The reagent of choice for detecting latent blood traces on all types of surfaces is luminol, but its main disadvantage is a high degree of sensitivity to oxidising contaminants in the blood sample. If household bleach is used to clean bloodstains, presumptive tests are invalidated. Hypochlorites, however, are known to be unstable and deteriorate over time, and this feature could be of help in preventing household bleach-indu…
How and why does willow biochar increase a clay soil water retention capacity?
2018
Addition of biochar into a soil changes its water retention properties by modifying soil textural and structural properties. In addition, internal micrometer-scale porosity that is able to directly store readily plant available water affects soil water retention properties. This study shows how precise knowledge of the internal micrometer-scale pore size distribution of biochar can deepen the understanding of the biochar-water interactions in soils. The micrometer-scale porosity of willow biochar was quantitatively and qualitatively characterized using X-ray tomography, 3D image analysis and Helium ion microscopy. The effect of biochar application on clay soil water retention was studied by…
Preliminary study on analysis and removal of wax from a Carrara marble statue
2015
This preliminary study has mainly focused on the wax identification by nuclear magnetic resonance (NMR) and removal. Wax is used for many purposes in the field of art as protective coatings on wooden, stone or metal objects. From the comparison of the spectra H NMR and in particular with the correspondence of the resonance peaks of the samples taken from the statue and beeswax and paraffin, we can conclude that the wax applied on the statue surface is beeswax. From our data, it can be concluded that, to remove the beeswax, from any stone support, the more effective solvent is the mixture of cyclohexane/ethyl acetate. The removal percentages ranged from 19 to 99%. Lower percentages of remova…
Thermal conductivity of disperse insulation materials and their mixtures
2017
Development of new, more efficient thermal insulation materials is a key to reduction of heat losses and contribution to greenhouse gas emissions. Two innovative materials developed at Thermeko LLC are Izoprok and Izopearl. This research is devoted to experimental study of thermal insulation properties of both materials as well as their mixture. Results show that mixture of 40% Izoprok and 60% of Izopearl has lower thermal conductivity than pure materials. In this work, material thermal conductivity dependence temperature is also measured. Novel modelling approach is used to model spatial distribution of disperse insulation material. Computational fluid dynamics approach is also used to est…
Determination of water intrusion heat in hydrophobic microporous materials by high pressure calorimetry
2010
International audience; The understanding of interactions between a solid surface and a non-wetting liquid still remains of fundamental interest in numerous research fields, from chemistry to biology. This work focuses on the mechanisms of water intrusion in hydrophobic microporous materials through the thermal analysis of the phenomenon. A specific calorimetric technique coupled to high pressure equipment has been developed to investigate equilibrium thermal effects in such thermodynamic systems from 0 to 400 MPa under isothermal conditions. First validation tests of this method were carried out by compressing degassed water in a constant volume V with successive small pressure increments …
Effect of exercises with weight vests and a patient education programme for women with osteopenia and a healed wrist fracture: a randomized, controll…
2015
Background Exercise programmes have shown to be important for the prevention of fractures in patients with established osteoporosis. However, few studies have evaluated the effect of such programmes for women with low bone mineral density (BMD) (osteoporosis or osteopenia) who have already suffered a fracture. Studies have indicated that exercise programmes concentrating on muscular strength and dynamic balance have a positive effect on significant risk factors for falls such as quadriceps strength and balance. The aim of the present study was to assess the effect of a 6-month exercise programme and a patient education component (OsteoACTIVE) on quadriceps strength, BMD, dynamic balance, wa…
Irreversible modifications of the porous microstructure of soluble anhydrite β-CaSO4 induced by hydration-dehydration cycles
2006
26 pages; The internal surface area of hexagonal (soluble) primary anhydrite CaSO4 produced by dehydration of gypsum decreases by about 70 % when the anhydrite is successively subjected to rehydration and dehydration at room temperature in humid air and in vacuum respectively. In the rehydration step, the hemihydrate is formed; its dehydration yields secondary anhydrite. Additional hydration-dehydration cycles in the same conditions have a much smaller effect. The first cycle also brings about a modification of the t-plot, which reveals that the micropores of primary anhydrite are irreversibly healed. Mercury intrusion porosimetry shows that the primary dehydration of gypsum also generates …
Porous architecture and thermal properties of thermal barrier coatings deposited by suspension plasma spray
2020
Abstract Besides the intrinsic low heat transfer capability of material, the thermal insulation property of thermal barrier coatings (TBCs) also relies on their microstructures. For better understanding the relationship between process parameters, porous architecture, and thermal properties of coatings, YSZ coatings were firstly manufactured by suspension plasma spray (SPS). Afterwards their total porosities were characterized by using the technique of X-ray transmission, the nano/submicro pores in those coatings were detected with Ultra-Small Angle X-ray Scattering (USAXS), and the thermal properties of coatings were measured using the laser flash method. The results indicated that: i) the…
A method for the preparation of repacked soil cores with homogeneous aggregates for studying microbial nitrogen transformations under highly controll…
1998
International audience; he feasibility of studies on nitrate transformations during incubation in controlled conditions of air-filled porosity using a method of soil core preparation was investigated. Repacked cores were obtained by uniaxial confined compression in a cylindrical mould of a mass of calibrated and conveniently wet aggregates with a water content selected to saturate the textural porosity of the soil aggregates, imposing structural porosity and thereby producing controlled conditions of aeration. The principle and the descrip- tion of the incubation method are explained and some denitrification and respiration data obtained with low and increasing OZ partial pressures are pres…