Development and test of a method for the simultaneous measurement of heat capacity and thermal diffusivity by laser-flash technique at very high temperatures: application to uranium dioxide

The "classical" laser-flash method is today the most used technique to measure the thermal diffusivity of a wide range of materials. This work describes the development of a new technique, based on the laser-flash method, which measures simultaneously on the same sample with an absolute method the thermal diffusivity and the specific heat, and its application to a number of high melting-point refractory materials. In this work, a new data processing procedure, which takes radiative and conductive heat losses into consideration, is introduced, and the thermal diffusivity, a, and specific heat, cp are determined by fitting the entire experimental transient temperature curve. The thermal conductivity is then calculated from the measured a and cp values via the relationship = apcP, where p is the density of the material. For the calculation the measured room temperature values of p corrected to the temperature of interest via literature data on thermal expansion are used. The new technique is applied to measure the specific heat, thermal diffusivity of POCO AXM 5Q graphite, zirconium dioxide and uranium dioxide (materials of scientific and technological interest) at very high temperatures (above 1800K) from which thermal conductivity values can be calculated. The values obtained, having a precision of ~2% in the case of the thermal diffusivity, and ~7% for the specific heat and the thermal conductivity, are discussed and compared with literature data. The results obtained for uranium dioxide are used for a critical analysis of the physical mechanisms underlying the heat transport in this material

Modeling Transient Heat Conduction and Radiative Transport in Semitransparent Media: A Tool for the Interpretation of Reflectivity Data

In this work the problem of interpretation of reflectivity data for semitransparent materials at high temperatures is addressed. A detailed analysis of the transient thermal response of a participating medium subjected to a pulse of finite energy is performed using a new method developed to solve the general equation of energy transfer for a conductive, absorbing, emitting, and scattering medium. The model, previously presented for a material with constant optical properties (Musella, Tschudi, Int J Thermophys 26:981, 2005), has been upgraded to encompass a much wider scenario where the thermophysical and optical properties are temperature dependent. This allows the study of the transient reflectivity of laser-heated samples where high heating rates and strong temperature gradients occur near the surface. Considerable differences of the reflectivity values for the same surface temperature calculated in the heating and cooling phases, both different from the corresponding values for an isothermal sample, are reported in accordance with experimental result

A Novel Vasoactive Peptide “PG1” from Buffalo Ice-Cream Protects from Angiotensin-Evoked High Blood Pressure

Arterial hypertension is the most important risk factor for cardiovascular diseases, myocardial infarction, heart failure, renal failure and peripheral vascular disease. In the last decade, milk-derived bioactive peptides have attracted attention for their beneficial cardiovascular properties. Methods: Here, we combined in vitro chemical assay such as LC-MS/MS analysis of buffalo ice cream, ex vivo vascular studies evaluating endothelial and smooth muscle responses using pressure myograph, and translational assay testing in vivo the vascular actions of PG1 administration in murine models. Results: We demonstrate that a novel buffalo ice-cream-derived pentapeptide “QKEPM”, namely PG1, is a stable peptide that can be obtained at higher concentration after gastro-intestinal digestions (GID) of buffalo ice-cream (BIC). It owns potent vascular effect in counteract the effects of angiotensin II-evoked vasoconstriction and high blood pressure levels. Its effects are mediated by the inhibitory effect on AT1 receptor leading to a downregulation of p-ERK½/Rac1-GTP and consequent reduction of oxidative stress. Conclusions: These results strongly candidate PG1, as a novel bioactive peptide for the prevention and management of hypertension, thus expanding the armamentarium of preventive strategies aimed at reducing the incidence and progression of hypertension and its related cardiovascular complication

Prevalence and risk factors associated with cat parasites in Italy: a multicenter study

Background: Parasites that infect cats include protozoa, helminths and arthropods, many of which are transmissible to humans. Effective control relies on a good knowledge of parasite distribution and the risk factors for infection. The present study was aimed at evaluating the prevalence of major feline parasites in Italy and the risk factors associated with their occurrence. Methods: Over a 12-month study period, feces, hair and ectoparasites from naturally infected cats from feral colonies, shelters and private households were analyzed at 13 study centers across Italy. Samples from these cats (n = 987) were analyzed at all centers using the same diagnostic methods. Prevalence values and risk factors were evaluated statistically for the identification of predictors of risk. Results: The overall prevalence of gastro-intestinal and broncho-pulmonary (BP) nematodes was 35.9% (354/987). Toxocara cati was the most prevalent species (253/987; 25.6%), followed by Ancylostomatidae (98/987; 9.9%). Among BP nematodes, Aelurostrongylus abstrusus was the most common (76/987; 7.7%). Approximately 35.7% (352/987) of the study population was infested by ectoparasites, of which the most common were fleas (29.4%, 290/987), followed by ear mites Otodectes cynotis (9.8%, 97/987). Predictors of risk for parasite infection included age, a predominantly or exclusively outdoor lifestyle, geographic area and lack of antiparasitic treatment. Conclusions: Both ecto- and endoparasites are still common in cats throughout Italy, many of them being of zoonotic concern and vectors of pathogens to humans. Given the presence of parasites throughout the entire study period, year-round treatment should be considered. Furthermore, data confirm the need to protect the human–animal bond using proper endo- and ectoparasiticides to reduce the risk of human infection, in application of the One-Health concept

Peptidomimetics as potent dual SARS-CoV-2 cathepsin-L and main protease inhibitors: In silico design, synthesis and pharmacological characterization

In this paper we present the design, synthesis, and biological evaluation of a new series of peptidomimetics acting as potent anti-SARS-CoV-2 agents. Starting from our previously described Main Protease (MPro) and Papain Like Protease (PLPro) dual inhibitor, CV11, here we disclose its high inhibitory activity against cathepsin L (CTSL) (IC50 = 19.80 ± 4.44 nM), an emerging target in SARS-CoV-2 infection machinery. An in silico design, inspired by the structure of CV11, led to the development of a library of peptidomimetics showing interesting activities against CTSL and Mpro, allowing us to trace the chemical requirements for the binding to both enzymes. The screening in Vero cells infected with 5 different SARS-CoV-2 variants of concerns, highlighted sub-micromolar activities for most of the synthesized compounds (13, 15, 16, 17 and 31) in agreement with the enzymatic inhibition assays results. The compounds showed lack of activity against several different RNA viruses except for the 229E and OC43 human coronavirus strains, also characterized by a cathepsin-L dependent release into the host cells. The most promising derivatives were also evaluated for their chemical and metabolic in-vitro stability, with derivatives 15 and 17 showing a suitable profile for further preclinical characterization

Dependence of the Melting Temperature on Pressure up to 2000 Bar in Uranium Dioxide, Tungsten and Graphite.

The melting point of uranium dioxide, tungsten and graphite was measured as a function of the isostatic pressure up to 2000 bar, in a laser-heated autoclave filled with inert gas. The measured melting curves and their slopes were compared with the predictions obtained from the Clausius-Clapeyron equation and the existing thermochemical data of these substances. Whilst for tungsten and graphite the results show a reasonable agreement with the equilibrium thermodynamic calculation, the melting point of UO2 increases with the equilibrium thermodynamic calculation, the melting point of UO2 increases with pressure with a slope more than three times larger than expected.JRC.E-Institute for Transuranium Elements (Karlsruhe

Carbon Capture and Storage - Burying Bad News?

Near-Zero Emission Technologies foresee application of Carbon Capture and Storage (CCS) to fossil fuel-powered energy plantsJRC.DDG.F.2-Cleaner energ

The Molten State of Graphite. An Experimental Study.

Sub-second laser heating technique has been succesfully applied for graphite melting under controlled isobaric conditions. During the applied pulses, relatively large amounts of graphite were melted and subsequently solidified under good stability conditions of the liquid mass. The SLV triple point was determined. From metallographic analysis of the quenched liquid, the expansion upon melting could be estimated. A mathematical model was then applied to deduce the thermal conductivity of liquid carbon. Both experimental observations and calculation results indicate a non-metallic nature of liquid carbon in the pressure range of 110-2500 bar. Finally, an analysis of the melting line Tm(p) based on Simpon's empirical equation of state confirms the self-consistency of all results obtained.JRC.E-Institute for Transuranium Elements (Karlsruhe

Advances in the Use of Laser-Flash Techniques for Thermal Diffusivity Measurement.

A laser-flash apparatus has been constructed, and is here presented, for the measurement of thermal diffusivity. The apparatus is specially designed to operate under the stringent conditions imposed by the requirement to measure the thermal diffusivity of highly radioactive reactor-irradiated nuclear fuels. These materials require the adaption of mechanical, optical and electrical technologies for use in a alpha-gamma hot-cell environment.JRC.E-Institute for Transuranium Elements (Karlsruhe