Self-heating function of carbon nanofiber cement pastes

The viability of carbon nanofiber (CNF) composites in cement matrices as a self-heating material is reported in this paper. This functional application would allow the use of CNF cement composites as a heating element in buildings, or for deicing pavements of civil engineering transport infrastructures, such as highways or airport runways. Cement pastes with the addition of different CNF dosages (from 0 to 5% by cement mass) have been prepared. Afterwards, tests were run at different fixed voltages (50, 100 and 150V), and the temperature of the specimens was registered. Also the possibility of using a casting method like shotcrete, instead of just pouring the fresh mix into the mild (with no system’s efficiency loss expected) was studied. Temperatures up to 138 °C were registered during shotcrete-5% CNF cement paste tests (showing initial 10 °C/min heating rates). However a minimum voltage was required in order to achieve a proper system functioning.

Mapping Binary Liquid-Vapor or Liquid-Liquid-Vapor Equilibria Regions, including the Different Azeotropic Behaviours, as a Function of the NRTL Binary Parameters

13th Mediterranean Congress of Chemical Engineering (Sociedad Española de Química Industrial e Ingeniería Química, Fira Barcelona, Expoquimia), Barcelona, September 30-October 3, 2014

Indicators of obesity and the educational attainment of the Czech female population

The aim of this paper was to evaluate the relationship between selected indicators of obesity and the highest completed level of education in the adult female population of the Czech republic. As basic indicators of obesity, these following parameters were selected and measured via the bioimpedance method on the device InBody 720: BMI, WHR (waist-to-hip ratio), % body fat, % skeletal muscle mass, fitness score. The educational attainment of the tested women was inquired by a questionnaire. Based on the responses, we subsequently divided our sample into four categories according to the level of education: primary education, secondary education-apprenticeship, secondary education-graduate diploma, and university. The research was realized within the project CZ.1.07/2.3.00/20.0044. The measurements on the device InBody 720 and the accompanying survey were conducted between 2011-2013 in different regions of the Czech Republic. The sample consisted of 754 women divided into 3 age groups (18-39, 40-59, 60+ years). Based on the results (p<0.05), we can say that average values of the indicators obesity (BMI: 22.76, 24.88, 26.49 kg/m2, WHR: 0.85, 0.88, 0.90 and % body fat: 25.76, 30.23, 34.62%) increase with the increasing age of examined women. The average values of the fitness score (75.53, 73.86, 70.04 points) and % skeletal muscle mass (40.78, 38.15, 33.95%) decrease with increasing age. With regard to the educational attainment, women with secondary education-apprenticeship achieved the worst results. In contrast, the values in university educated women were the best in most indicators of obesity.

Energy Loss Function of Solids Assessed by Ion Beam Energy-Loss Measurements: Practical Application to Ta2O5

We present a study where the energy loss function of Ta2O5, initially derived in the optical limit for a limited region of excitation energies from reflection electron energy loss spectroscopy (REELS) measurements, was improved and extended to the whole momentum and energy excitation region through a suitable theoretical analysis using the Mermin dielectric function and requiring the fulfillment of physically motivated restrictions, such as the f- and KK-sum rules. The material stopping cross section (SCS) and energy-loss straggling measured for 300–2000 keV proton and 200–6000 keV helium ion beams by means of Rutherford backscattering spectrometry (RBS) were compared to the same quantities calculated in the dielectric framework, showing an excellent agreement, which is used to judge the reliability of the Ta2O5 energy loss function. Based on this assessment, we have also predicted the inelastic mean free path and the SCS of energetic electrons in Ta2O5.