Accurate experimental (p, ρ, T) data for the introduction of hydrogen into the natural gas grid: Thermodynamic characterization of the nitrogen-hydrogen binary system from 240 K to 350 K and pressures up to 20 MPa

The experimental density data of the binary system nitrogen-hydrogen available at the time of the development of the equation of state for natural gases and related mixtures, GERG-2008, were limited to hydrogen contents higher than 0.15 (amount-of-substance fraction) and temperatures above 270 K. This work provides accurate experimental (p, ρ, T) data for three binary mixtures of nitrogen and hydrogen: (0.95 N2 + 0.05 H2), (0.90 N2 + 0.10 H2), and (0.50 N2 + 0.50 H2) at temperatures of (240, 250, 260, 275, 300, 325, and 350) K, thus extending the range of available experimental data to low hydrogen contents and low temperatures. The density measurements were performed by using a single-sinker densimeter with magnetic suspension coupling at pressures up to 20 MPa. Experimental data were compared with the corresponding densities calculated from the GERG-2008 and the AGA8-DC92 equations of state. The relative deviations of the experimental data from both equations of state were within the estimated uncertainty value of the equations. Therefore, the experimental data agree very well with the values estimated from the equations. The virial coefficients B(T,x), C(T,x), and D(T,x) as well as the second interaction virial coefficient for the nitrogen-hydrogen binary system were also calculated from the experimental data set at temperatures from (240 to 350) K. The resulting values agree with those from literature.2018-11-03MEC ENE2013-47812-REuropean Commission’s ENG54Junta de Castilla y León VA035U1

Accurate experimental (p, ρ, T) data and virial coefficients for the (methane and helium) binary system

The quality and the availability of experimental data limit the achievable accuracy of multiparameter equations of state, such as the GERG-2008. Referring to the fundamentals of this wide-range equation of state, no suitable data were available for many mixtures containing helium. This work provides accurate experimental (p, ρ, T) data for three binary mixtures of methane with helium: (0.95 (amount-of-substance fraction) CH4 + 0.05 He) and (0.90 CH4 + 0.10 He) at temperatures of (240, 250 and 260) K, and (0.50 CH4 + 0.50 He) from (240 to 400) K. This work is a continuation of a previous one which reported accurate experimental (p, ρ, T) data for the (0.95 CH4 + 0.05 He) and the (0.90 CH4 + 0.10 He) binary mixtures in the temperature range from the (250 to 400) K. All density measurements were performed by using a single-sinker densimeter with magnetic suspension coupling at pressures up to 20 MPa. Experimental data were compared with the corresponding densities calculated from the GERG-2008 and the AGA8-DC92 equations of state. Deviations from the GERG-2008 are much larger than from the AGA8-DC92 (up to –6.5 %). These deviations increased with decreasing temperature, with increasing pressure, and with increasing helium fraction. In contrast, deviations from the AGA8-DC92 are within the 0.5 % band. The experimental values were also used to calculate the second interaction virial coefficient for this mixture.2018-05-30MEC ENE2013-47812-REuropean Commission ENG5

Experimental determination of (p, ρ, T) data for binary mixtures of methane and helium

Innovación EducativaThe basis for the development and evaluation of equations of state for mixtures is experimental data for several thermodynamic properties. The quality and the availability of experimental data limit the achievable accuracy of the equation. Referring to the fundamentals of GERG-2008 wide-range equation of state, no suitable data were available for many mixtures containing secondary natural gas components. This work provides accurate experimental (p, ρ, T) data for two binary mixtures of methane with helium (0.95 (amount-of-substance fraction) CH4 + 0.05 He and 0.90 CH4 + 0.10 He). Density measurements were performed at temperatures between 250 K and 400 K and pressures up to 20 MPa by using a single-sinker densimeter with magnetic suspension coupling. Experimental data were compared with the corresponding densities calculated from the GERG-2008 and the AGA8-DC92 equations of state. Deviations from GERG-2008 were found within a 2 % band for the (0.95 CH4 + 0.05 He) mixture but exceeded the 3 % limit for the (0.95 CH4 + 0.05 He) mixture. The highest deviations were observed at 250 K and pressures between 17 and 19 MPa. Values calculated from AGA8-DC92, however, deviated from the experimental data by only 0.1 % at high pressures and exceeded the 0.2 % limit only at temperatures of 300 K and above, for the (0.90 CH4 + 0.10 He) mixture.MEC ENE2013-47812-RJunta de Castilla y León Regional VA391A12-1European Commission's ENG5

Speed of sound for three binary (CH4 + H2) mixtures from p = (0.5 up to 20) MPa at T = (273.16 to 375) K

Producción CientíficaSpeed of sound is one of the thermodynamic properties that can be measured with least uncertainty and is of great interest in developing equations of state. Moreover, accurate models are needed by the H2 industry to design the transport and storage stages of hydrogen blends in the natural gas network. This research aims to provide accurate data for (CH4 + H2) mixtures of nominal (5, 10, and 50) mol-% of hydrogen, in the p = (0.5 up to 20) MPa pressure range and with temperatures T = (273.16, 300, 325, 350, and 375) K. Using an acoustic spherical resonator, speed of sound was determined with an overall relative expanded (k = 2) uncertainty of 220 parts in 106 (0.022 %). Data were compared to reference equations of state for natural gas-like mixtures, such as AGA8-DC92 and GERG-2008. Average absolute deviations below 0.095% and percentage deviations between 0.029% and up to 0.30%, respectively, were obtained. Additionally, results were fitted to the acoustic virial equation of state and adiabatic coefficients, molar isochoric heat capacities and molar isobaric heat capacities as perfect-gas, together with second and third acoustic virial coefficients, and were estimated. Density second virial coefficients were also obtained.Ministerio de Economía, Industria y Competitividad project ENE2017-88474-RJunta de Castilla y León VA280P1

Speed of sound data and acoustic virial coefficients of two binary (N2 + H2) mixtures at temperatures between (260 and 350) K and at pressures between (0.5 and 20) MPa

Producción CientíficaThis work aims to address the technical concerns related to the thermodynamic characterization of gas mixtures blended with hydrogen for the implementation of hydrogen as a new energy vector. For this purpose, new experimental speed of sound measurements have been done in gaseous and supercritical phases of two binary mixtures of nitrogen and hydrogen using the most accurate technique available, i.e., the spherical acoustic resonator, yielding an experimental expanded (k = 2) uncertainty of only 220 parts in 106 (0.022%). The measurements cover the pressure range between (0.5 and 20) MPa, the temperature range between (260 and 350) K, and the composition range with a nominal mole percentage of hydrogen of (5 and 10) mol%, respectively. From the speed of sound data sets, thermophysical properties that are relevant for the characterization of the mixture, namely the second βa and third γa acoustic virial coefficients, are derived. These results are thoroughly compared and discussed with the established reference mixture models valid for mixtures of nitrogen and hydrogen, such as the AGA8-DC92 EoS, the GERG-2008 EoS, and the recently developed adaptation of the GERG-2008 EoS, here denoted GERG-H2_improved EoS. Special attention has been given to the effect of hydrogen concentration on those properties, showing that only the GERG-H2_improved EoS is consistent with the data sets within the experimental uncertainty in most measuring conditions.Ministerio de Ciencia, Innovación y Universidades - Fondo Europeo de Desarrollo Regional (project ENE2017-88474-R)Ministerio de Ciencia, Innovación y Universidades (fellowship BEAGAL18/00259)Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (project VA280P18

A new method for accurate assessment of DNA quality after bisulfite treatment

The covalent addition of methylgroups to cytosine has become the most intensively researched epigenetic DNA marker. The vast majority of technologies used for DNA methylation analysis rely on a chemical reaction, the so-called ‘bisulfite treatment’, which introduces methylation-dependent sequence changes through selective chemical conversion of non-methylated cytosine to uracil. After treatment, all non-methylated cytosine bases are converted to uracil but all methylated cytosine bases remain cytosine. These methylation dependent C-to-T changes can subsequently be studied using conventional DNA analysis technologies. The bisulfite conversion protocol is susceptible to processing errors, and small deviation from the protocol can result in failure of the treatment. Several attempts have been made to simplify the procedure and increase its robustness. Although significant achievements in this area have been made, bisulfite treatment remains the main source of process variability in the analysis of DNA methylation. This variability in particular impairs assays, which strive for the quantitative assessment of DNA methylation. Here we present basic mathematical considerations, which should be taken into account when analyzing DNA methylation. We also introduce a PCR-based assay, which allows ab initio assessment of the DNA quality after bisulfite treatment and can help to prevent inaccurate quantitative measurement resulting from poor bisulfite treatment

Non-aqueous synthesis of ultrasmall NiO nanoparticle-intercalated graphene composite as active electrode material for supercapacitors

With the vast exploration of the applications of graphene, researchers are assessing different methods for fabricating graphene-based electrode material with high capacitance but low material and energy costs. In this study, reduced graphene oxide/nickel oxide (RGO/NiO) nanocomposites were prepared using a non-aqueous solvent-based method followed by calcination. Nickel acetate tetrahydrate and tert-butanol were used as the precursor and solvent, respectively. Ultrasmall nickel oxide nanoparticles, ca. 8.0 nm in size, were deposited on the surface of the graphene sheets simultaneously with the partial reduction of graphene oxide. The resulting RGO/NiO electrode exhibited a high capacitance of 689 F g⿿1 at a current density of 0.8 A g⿿1. After 1500 cycles, the specific retention and the coulombic efficiency yielded to 86.34% and 96.39%, respectively, which supports the viability of this composite as an alternative activated material with high electrochemical performance