Thermogenic Characterization and Antifungal Susceptibility of Candida auris by Microcalorimetry

Candida auris has emerged globally as a multidrug-resistant fungal pathogen. Isolates of C. auris are reported to be misidentified as Candida haemulonii. The aim of the study was to compare the heat production profiles of C. auris strains and other Candida spp. and evaluate their antifungal susceptibility using isothermal microcalorimetry. The minimum heat inhibitory concentrations (MHIC) and the minimum biofilm fungicidal concentration (MBFC) were defined as the lowest antimicrobial concentration leading to the lack of heat flow production after 24 h for planktonic cells and 48 h for biofilm-embedded cells. C. auris exhibited a peculiar heat production profile. Thermogenic parameters of C. auris suggested a slower growth rate compared to Candida lusitaniae and a different distinct heat profile compared to that of C. haemulonii species complex strains, although they all belong to the Metschnikowiaceae clade. Amphotericin B MHIC and MBFC were 0.5 µg/mL and ≥8 µg/mL, respectively. C. auris strains were non-susceptible to fluconazole at tested concentrations (MHIC > 128 µg/mL, MBFC > 256 µg/mL). The heat curve represents a fingerprint of C. auris, which distinguished it from other species. Treatment based on amphotericin B represents a potential therapeutic option for C. auris infection.

Behavior of High Strength Concrete at High Temperatures

Concrete is considered as a non-combustible building material. However, at High-Performance Concrete (HPC) is due to its dense structure more likely to occur in explosive spalling. This results in lost of load bearing capacity function of concrete. This paper deals with design, production and testing of the cement-based concrete with the use of different fibers (polypropylene fibers and cellulose fibers). It also assesses the influence of high temperature on strength, visual changes of specimens, changes of surface and degradation of testing specimens due to heat loads according to normative heat curve and also according to hydrocarbon curve.

Assessment of T-History Method Variants to Obtain Enthalpy–Temperature Curves for Phase Change Materials With Significant Subcooling

To assess the potential of thermal energy storage systems using phase change materials (PCMs), numerical simulations rely on an enthalpy–temperature curve (or equivalent specific heat curve) to model the PCM thermal storage behavior. The so-called “T-history method” can be used to obtain an enthalpy–temperature curve (H versus T) through conventional laboratory equipment and a simple experimental procedure. Different data processing variants of the T-history method have been proposed yet no systematic comparison between these versions exists in the literature nor is there a consensus as to which should be used to obtain reliable enthalpy–temperature curves. In this paper, an inorganic salt hydrate is tested in both heating and cooling. Four different data processing variants of the T-history method are used to characterize the PCM and produce enthalpy–temperature curves for this original experimental data set. Differences in the results produced by the different methods are discussed, the issues encountered are indicated, and possible approaches to overcome these problems are provided. A specific variant is recommended when using the T-history method to determine enthalpy–temperature curves. For PCMs that exhibit subcooling, an alternative interpretation using an absolute temperature interval is described so that the subcooling phase is taken into account in the enthalpy–temperature curve.

Review on Water Radiolysis in the Fukushima Daiichi Accident: Potential Cause of Hydrogen Generation and Explosion

Although the water radiolysis, decomposition of water by radiation, is a well-known phenomenon the exact mechanism is not well characterized especially for severe accidents. The author first reviewed the water radiolysis phenomena in LWRs during normal operation to severe accidents (e.g., TMI- and Chernobyl accidents) and performed a scoping estimation of the amount of radiological hydrogen generation, accumulation and release for the Fukushima Daiichi accident. The estimation incorporates the decay heat curve after a reactor trip combined with G-values. As much as 450 cubic meters-STP of accumulated hydrogen gas is estimated to be located inside the PCV just prior to the hydrogen explosion which occurred a day after the reactor trip in Unit 1. When a set of radiological chain reactions are incorporated the resultant reverse reactions substantially reduce the hydrogen generation, even when removal of molecular products (i.e., oxygen and hydrogen) is assumed stripped rapidly from boiling water through bubbles. Even in the most favorable configuration a typical amount of hydrogen gas reduces to only several tens of cubic meters. Finally, the author tested a new mechanism, “radiation-induced electrolysis,” which had been applied to his corrosion studies for last several years. His theory has been verified with the published in-pile test data, although he has never tried to apply this to his severe accident study. The predicted results indicated that the total inventory of hydrogen gas inside RPV may reach as much as 1000 cubic meters in just 3 hours during the SBO due to a high decay heat soon after the reactor trip through this process.

The Study on Thermal Properties of Solid Solution (K, NH4)Cl

Solid solutions with different compositions, mNH4Cl·KCl and NH4Cl·nKCl (m，n≥1), were prepared by the constant speed cooling method. The thermal stability of the solid solutions was determined by TG-DTA. The results show that mNH4Cl·KCl crystals change its crystal form at 180°C, decompose into ammonia and hydrogen chloride gas at 330°C, melt at 790°C, and finally evaporate at around 820°C. Its evaporation temperature increases with the increasing of potassium chloride content in the samples. The Solid solution of NH4Cl·nKCl decomposes to ammonia and hydrogen chloride gas at 230°C, melts at 790°C, and evaporates at 800°C. The continuous specific heat curve of the solid solution (NH4, K)Cl were also determined. These data provide a theoretical basis for further research on solid solution properties.

A model for evaluating and predicting high-temperature thermal expansion

In this paper, a new set of experimental data, αVKTV, representing the partial temperature derivative of the work done by the thermal pressure of the solid, is fitted by n terms of a modified Einstein model. Experimental data show that αVKTV, not αVKT, approaches a constant value at high temperature. Based on the observed linear relationship of isothermal bulk modulus with temperature at high temperature, thermal expansion can be evaluated by fitting αVKTV data. Our previous results have shown that at low temperature or for materials with less variable bulk modulus and expansivity, thermal expansion data can be simply approximated by an n term Einstein model. More generally and for many materials, αVKTV data resemble an isochoric specific heat curve. With this method, thermal expansion can be predicted at high temperatures from low and intermediate temperature range data. With accurate thermal expansion data, high temperature bulk moduli can also be predicted.