Search results for "thermal [radiation]"

Interactions of the alternating double stranded copolymer poly(dA-dT).poly(dA-dT) with NiCl2 and CdCl2: solution behaviour

2007

The thermal denaturation of the synthetic high molecular weight double stranded polynucleotide poly(dA-dT) x poly(dA-dT) has been studied in aqueous buffered solution (Tris 1.0 mM; pH 7.8+/-0.2) in the presence of increasing concentrations of either Ni(2+) (borderline cation) or Cd(2+) (soft cation) at four different constant ionic strength values (NaCl), making use of UV and circular dichroism (CD) spectroscopies. The experimental results show that the B-type double helix of the polymer is stabilized against thermal denaturation in the presence of both cations at low concentrations, relative to the systems where only NaCl is present, in the same conditions of ionic strength and pH. The eff…

Effects of Saline and Deficit Irrigation on Soil-Plant Water Status and Potato Crop Yield under the Semiarid Climate of Tunisia

2019

Water supplies have been decreasing in several semi-arid regions, and it is therefore necessary to adopt irrigation strategies aimed at maximizing water use efficiency. In this paper, the effects of saline and deficit irrigation on water use efficiency and on potato crop response, based on observations of soil and plant water status, were investigated. Experiments were carried out in Central Tunisia, by monitoring potato crop growth during two seasons in four distinct treatments (T1&ndash

Thermal desorption gas chromatography with mass spectrometry study of outgassing from polymethacrylimide foam (Rohacell®)

2015

Polymethacrylimide foams are used as light structural materials in outer-space devices; however, the foam closed cells contain volatile compounds that are outgassed even at low temperatures. These compounds ignite as plasmas under outer-space radiation and the intense radio-frequency fields used in communications. Since plasmas may cause spacecraft fatal events, the conditions in which they are ignited should be investigated. Therefore, qualitative and quantitative knowledge about polymethacrylimide foam outgassing should be established. Using thermogravimetric analysis, weight losses reached 3% at ca. 200°C. Thermal desorption gas chromatography with mass spectrometry detection was used to…

Evaluation of innovative thermal insulation systems for a sustainable envelope

2017

La memoria presenta i risultati ottenuti su sistemi di isolamento termico per l’involucro edilizio. Si presentano i risultati ottenuti tramite simulazioni informatiche che hanno consentito di verificare e ottimizzare la trasmissione del calore attraverso un sistema sottovuoto in vetro per le facciate trasparenti. Inoltre la possibilità offerta dal riciclo del materiale di scarto della potatura dell’Opunthia Ficus Indica (fichi d’india) che,opportunamente trattato ha permesso di ottenere un materiale isolante (Brevetto n. 1402131), in forma di pannello o in grani sfusi, (valori di coibenza termica 0.071­0.057 W/mK). The paper presents the results of the research on thermal insulation systems…

Quantum Effects on the Diffusivity of Hydrogen Isotopes in Zeolites

2019

The molecular sieving of H2 and its isotopes produced by nuclear plants is a long-standing research where some adsorption processes are well identified. However, some mechanisms governing the diffu...

Josephson-based Threshold Detector for Lévy-Distributed Current Fluctuations

2019

We propose a threshold detector for Lévy-distributed fluctuations based on a Josephson junction. The Lévy-noise current added to a linearly ramped bias current results in clear changes in the distribution of switching currents out of the zero-voltage state of the junction. We observe that the analysis of the cumulative distribution function of the switching currents supplies information on both the characteristics' shape parameter α of the Lévy statistics. Moreover, we discuss a theoretical model, which allows characteristic features of the Lévy fluctuations to be extracted from a measured distribution of switching currents. In view of these results, this system can effectively find an appl…

2012

classical and quantum systems are investigated. First, the role of multiplicative and additive noise in a classical metastable system is analyzed. The mean lifetime of the metastable state shows a nonmonotonic behavior with a maximum as a function of both the additive and multiplicative noise intensities. In the second system, the simultaneous action of thermal and non-Gaussian noise on the dynamics of an overdamped point Josephson junction is studied. The eect of a Levy noise generated by a Cauchy‐Lorentz distribution on the mean lifetime of the superconductive metastable state, in the presence of a periodic driving, is investigated. We find resonant activation and noise enhanced stability…

In-plane conductive heat tansfer in solid and porous planar structures

2011

Methods for determining the in-plane thermal diffusivity in a planar sample geometry were developed. These methods were tested and verified by measuring planar metal samples with known thermal properties. The techniques used were based on heating the sample at one edge and recording the evolution of the temperature field in the sample by a thermographic camera. The temperature fields at different times were processed and then fitted by a solution to a heat equation describing the experimental setup, thermal diffusivity as one of the fitting parameters. In the first experimental setup the sample was placed in a weak constant flow of air, and the situation was improved in the second setup by …

A geostatistical approach to map near-surface soil moisture through hyperspatial resolution thermal inertia.

2021

Thermal inertia has been applied to map soil water content exploiting remote sensing data in the short and long wave regions of the electromagnetic spectrum. Over the last years, optical and thermal cameras were sufficiently miniaturized to be loaded onboard of unmanned aerial systems (UASs), which provide unprecedented potentials to derive hyperspatial resolution thermal inertia for soil water content mapping. In this study, we apply a simplification of thermal inertia, the apparent thermal inertia (ATI), over pixels where underlying thermal inertia hypotheses are fulfilled (unshaded bare soil). Then, a kriging algorithm is used to spatialize the ATI to get a soil water content map. The pr…

Thermal degradation of long-chain polyunsatured fatty acids during deodorization of fish oil

2006

International audience; Long-chain polyunsaturated fatty acids (LC-PUFA) of the n-3 series, particularly eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid, have specific activities especially in the functionality of the central nervous system. Due to the occurrence of numerous methylene-interrupted ethylenic double bonds, these fatty acids are very sensitive to air (oxygen) and temperature. Non-volatile degradation products, which include polymers, cyclic fatty acid monomers (CFAM) and geometrical isomers of EPA and DHA, were evaluated in fish oil samples obtained by deodorization under vacuum of semi-refined fish oil at 180, 220 and 250 °C. Polymers are the major degradation products g…