Mass Fraction Values Research Articles

The Effect of Age on 12 Chemical Element Contents in the Intact Prostate of Adult Men Investigated by Inductively Coupled Plasma Atomic Emission Spectrometry

The effect of age on 12 chemical element contents in intact prostate of 64 apparently healthy, 13-60-year-old men (mean age 36.5 years) was investigated by inductively coupled plasma atomic emission spectrometry. Mean values (M ± SΕΜ) for mass fraction (milligrams/kilogram, on dry weight basis) of Ba, Ca, Cu, Fe, K, Mg, Na, P, S, Sr, and Zn were: Ba 1.18 ± 0.12, Ca 2,178 ± 160, Cu 10.7 ± 0.9, Fe 122 ± 5, K 12,530 ± 360, Mg 1,100 ± 70, Na 10,470 ± 320, P 7,580 ± 300, S 8,720 ± 180, Sr 1.85 ± 0.28, and Zn 782 ± 97, respectively. The upper limit of mean content of V was ≤0.22 mg/kg. A tendency of age-related increase in Ca, Fe, Na, and Zn mass fraction as well an increase in Zn/Ba, Zn/Ca, Zn/Cu, Zn/Fe, Zn/K, Zn/Mg, Zn/Na, Zn/P, Zn/S, and Zn/Sr ratios in prostate was observed. A significant positive correlation was seen between the prostatic zinc and Ca, Cu, Fe, Mg, Na, and P contents.

STANDARD BIG BANG NUCLEOSYNTHESIS UP TO CNO WITH AN IMPROVED EXTENDED NUCLEAR NETWORK

Primordial or Big Bang nucleosynthesis (BBN) is one of the three strong evidences for the Big- Bang model together with the expansion of the Universe and the Cosmic Microwave Background radiation. In this study, we improve the standard BBN calculations taking into account new nuclear physics analyses and we enlarge the nuclear network until Sodium. This is, in particular, important to evaluate the primitive value of CNO mass fraction that could affect Population III stellar evolution. For the first time we list the complete network of more than 400 reactions with references to the origin of the rates, including \approx 270 reaction rates calculated using the TALYS code. Together with the cosmological light elements, we calculate the primordial Beryllium, Boron, Carbon, Nitrogen and Oxygen nuclei. We performed a sensitivity study to identify the important reactions for CNO, 9Be and Boron nucleosynthesis. We reevaluated those important reaction rates using experimental data and/or theoretical evaluations. The results are compared with precedent calculations: a primordial Beryllium abundance increase by a factor of 4 compared to its previous evaluation, but we note a stability for B/H and for the CNO/H abundance ratio that remains close to its previous value of 0.7 \times 10-15. On the other hand, the extension of the nuclear network has not changed the 7Li value, so its abundance is still 3-4 times greater than its observed spectroscopic value.

The Br, Fe, Rb, Sr, and Zn contents and interrelation in intact and morphologic normal prostate tissue of adult men investigated by energy‐dispersive X‐ray fluorescent analysis

A method for radionuclide‐induced (109Cd) energy‐dispersive X‐ray fluorescent (EDXRF) was used to determine Br, Fe, Rb, Sr, and Zn contents in intact and morphologic normal prostate tissues. Prostates were removed at necropsy from 64 men (mean age 36.5 years, range 13–60) who had died suddenly. All materials were divided into two parts. One part was morphologically examined, whereas chemical element contents of the other were estimated. Mean values (M ± SΕΜ) for mass fraction of Br, Fe, Rb, Sr, and Zn (mg kg−1 on dry‐weight basis) in the intact and morphologic normal prostate tissue were 35.5 ± 4.0, 107 ± 5.4, 17.1 ± 0.8, 1.9 ± 0.3, and 850 ± 79, respectively. Mean values (M ± SΕΜ) for Zn/Fe, Zn/Rb, and Zn/Sr ratios of mass fraction were 8.72 ± 0.80, 57.4 ± 7.2, and 567 ± 82, respectively. A strongly pronounced tendency of age‐related exponential increase in Zn mass fraction as well an increase in Zn/Fe, Zn/Rb, and Zn/Sr ratios in prostate was observed. A significant positive correlation was seen between the prostatic zinc and iron contents (p ≤ 0.05, r = 0.22) and between the prostatic zinc and bromine contents (p ≤ 0.01, r = 0.43). Copyright © 2011 John Wiley & Sons, Ltd.

An open-source library for the numerical modeling of mass-transfer in solid oxide fuel cells

The generation of direct current electricity using solid oxide fuel cells (SOFCs) involves several interplaying transport phenomena. Their simulation is crucial for the design and optimization of reliable and competitive equipment, and for the eventual market deployment of this technology. An open-source library for the computational modeling of mass-transport phenomena in SOFCs is presented in this article. It includes several multicomponent mass-transport models ( i.e. Fickian, Stefan–Maxwell and Dusty Gas Model), which can be applied both within porous media and in porosity-free domains, and several diffusivity models for gases. The library has been developed for its use with OpenFOAM ®, a widespread open-source code for fluid and continuum mechanics. The library can be used to model any fluid flow configuration involving multicomponent transport phenomena and it is validated in this paper against the analytical solution of one-dimensional test cases. In addition, it is applied for the simulation of a real SOFC and further validated using experimental data. Program summary Program title: multiSpeciesTransportModels Catalogue identifier: AEKB_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEKB_v1_0.html Program obtainable from: CPC Program Library, Queenʼs University, Belfast, N. Ireland Licensing provisions: GNU General Public License No. of lines in distributed program, including test data, etc.: 18 140 No. of bytes in distributed program, including test data, etc.: 64 285 Distribution format: tar.gz Programming language:: C++ Computer: Any x86 (the instructions reported in the paper consider only the 64 bit case for the sake of simplicity) Operating system: Generic Linux (the instructions reported in the paper consider only the open-source Ubuntu distribution for the sake of simplicity) Classification: 12 External routines: OpenFOAM® (version 1.6-ext) ( http://www.extend-project.de) Nature of problem: This software provides a library of models for the simulation of the steady state mass and momentum transport in a multi-species gas mixture, possibly in a porous medium. The software is particularly designed to be used as the mass-transport library for the modeling of solid oxide fuel cells (SOFC). When supplemented with other sub-models, such as thermal and charge-transport ones, it allows the prediction of the cell polarization curve and hence the cell performance. Solution method: Standard finite volume method (FVM) is used for solving all the conservation equations. The pressure-velocity coupling is solved using the SIMPLE algorithm (possibly adding a porous drag term if required). The mass transport can be calculated using different alternative models, namely Fick, Maxwell–Stefan or dusty gas model. The code adopts a segregated method to solve the resulting linear system of equations. The different regions of the SOFC, namely gas channels, electrodes and electrolyte, are solved independently, and coupled through boundary conditions. Restrictions: When extremely large species fluxes are considered, current implementation of the Neumann and Robin boundary conditions do not avoid negative values of molar and/or mass fractions, which finally end up with numerical instability. However this never happened in the documented runs. Eventually these boundary conditions could be reformulated to become more robust. Running time: From seconds to hours depending on the mesh size and number of species. For example, on a 64 bit machine with Intel Core Duo T8300 and 3 GBytes of RAM, the provided test run requires less than 1 second.

Oil concentration variation for bottled refrigerant/oil mixtures during extraction

In order to cut down setup cost for maintaining a constant concentration of oil in refrigerant/oil mixtures during experimentation, a bottle filled with a refrigerant/oil mixture having a predetermined oil concentration occurs as a suitable option. An attempt has been made to find the limits of variation in oil concentration during the extraction process so that the above technique can be suitably employed. Cases for oil with specific gravity in the range 0.80–1.00 and three refrigerants, viz., CO2, R290 and R134a are analysed. A sharp rise in oil concentration is revealed toward the end of the extraction process. It is proposed that oil concentration variation can be constrained by supplying the lowest residual/left mass fraction (LMF) value (or the maximum extractable mixture weight) along with other specifications for the refrigerant/oil mixture. A correlation is obtained to determine oil concentration during various stages of the extraction process.

A Modified Implicit Iterative Difference Algorithm for Stiff Chemical Kinetic Equations in Complex Combustion System

The splitting-operator method has been widely used in the numerical simulation of complex combustion system with its high computation efficiency. The main difficult encountered in the method is how to integrate the stiff chemical kinetics ordinary differential equation (ODE) efficiently and accurately in each grid node of flow field. Although several ODE software packages such as LSODE and VODE have very predominant performance in integrating stiff and non-stiff case, it couldn’t ensure the positivity of mass fraction in integrating stiff chemical kinetic ODE. A detail liquid rocket hypergolic bipropellant combination of Monomethylhydrazine (MMH)/Red Fuming Nitric Acid (RFNA) chemical mechanism consisting of 550 elementary reactions among 83 species was constituted basing on several relevant literatures firstly. And then a modified implicit iterative difference algorithm with variable time steps was developed to tackle the problem of mass fraction non-positive. The results from the integration of MMH /nitrogen tetroxide (NTO) chemical kinetic ODE indicate that the algorithm is always retain stability and positive value of mass fraction. The time step length would also be automatically adjusted at different chemical reaction time in the algorithm to keep its computational efficiency.

Technology Optimization on Preparation of Peanut Polypeptide Using Alcalase

In order to exploit and utilize the peanut protein resource and produce high additional value protein products, the preparation technology of peanut polypeptide from peanut protein isolate was investigated using Alcalase. The effects of influencing factors, enzyme dosage, substrate mass fraction, hydrolysis temperature, hydrolysis time and pH value, on hydrolysis was studied during the process of Alcalase hydrolyzing peanut protein isolate by single factor experiment and response surface methodology central composite design. The regression model for the relationship between the influencing factors and the soluble nitrogen mass concentration was established. The optimum parameters for Alcalase enzymatic reaction were obtained as follows: pH value 8.0, enzyme dosage 4762U/g substrate, substrate mass fraction 5%, hydrolysis temperature 50°C, hydrolysis time 180min, and then the soluble nitrogen mass concentration reached to 16.28mg/mL.

(Liquid + liquid) equilibria of methanol + isooctane + methylcyclohexane + ethylbenzene quaternary system at T = 303.15 K

Tie line data of {methanol + isooctane + methylcyclohexane}, {methanol + ethylbenzene + methylcyclohexane}, and {methanol + ethylbenzene + isooctane} ternary systems were obtained at T = 303.15 K. A quaternary system {methanol + isooctane + methylcyclohexane + ethylbenzene} was also studied at the same temperature. In order to obtain the binodal surface of the quaternary system, four quaternary sectional planes with several methylcyclohexane/isooctane ratios were studied. Experimental results show that the binodal surface in the solid diagram is small and that the highest ethylbenzene mass fraction values beyond which only one phase is present for the methanol-rich phase and hydrocarbon-rich one, respectively, are: 0.0783 and 0.0864 for P1, 0.0791 and 0.0906 for P2, 0.0798 and 0.0805 for P3, 0.0812 and 0.0935 for P4. So, if this quaternary system contains the correct methanol and hydrocarbons concentrations, this blend can be used as a reformulated gasoline because no phase separation should be observed. The distribution of ethylbenzene between both phases was also analysed. Ternary experimental results were correlated with the UNIQUAC and NRTL equation, and predicted with the original UNIFAC group contribution method. The equilibrium data of the three ternary systems were used to determine interactions parameters for the UNIQUAC equation. The UNIQUAC and NRTL equations are more accurate than the UNIFAC method for the ternary systems studied here, because this last model predicts an immiscibility region larger than the experimentally observed in the methanol-rich phase. The UNIQUAC equation fitted to the experimental data is more accurate than the UNIFAC method for this quaternary system.

Elemental analysis of a single-wall carbon nanotube candidate reference material

A material containing single-wall carbon nanotubes (SWCNTs) with other carbon species, catalyst residues, and trace element contaminants has been prepared by the National Institute of Standards and Technology for characterization and distribution as Standard Reference Material SRM 2483 Carbon Nanotube Soot. Neutron activation analysis (NAA) and inductively coupled plasma mass spectrometry (ICP-MS) were selected to characterize the elemental composition. Catalyst residues at percentage mass fraction level were determined with independent NAA procedures and a number of trace elements, including selected rare earth elements, were determined with NAA and ICP-MS procedures. The results of the investigated materials agreed well among the NAA and ICP-MS procedures and good agreement of measured values with certified values was found in selected SRMs included in the analyses. Based on this work mass fraction values for catalyst and trace elements were assigned to the candidate SRM.

Effect of operating variables on the production of nanoparticles by stirred media milling

AbstractThis paper investigates the effect of major operating variables on the production of stable nanoparticle suspensions in an attritor mill, which can serve as guidelines for the selection of major operating variables for desired comminution. Experimental work has been carried out to study the effect of major operating variables, such as slurry solid mass fraction, grinding media size, density and pin tip velocity on the milling efficiency of silica. The effect of these major operating variables on the variation of width of product size distribution was studied using response surface methodology. Size reduction was found to increase with increasing value of slurry solid mass fraction, until it reached a maximum and then decreased. The use of grinding media of smaller diameter was found to cause higher rates of size reduction and narrower particle size distribution than the use of larger grinding media. Pin tip velocity was found to be an important parameter affecting comminution results. Size reduction was found to increase on the order of increasing pin tip velocity, until it reached a maximum and then decreased. Grinding media of higher density was found to be more effective for size reduction and production of a narrower product size distribution. The results suggest that these variables affect the energy required to achieve a given product size during nanomilling. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

The Effects of Small-Scale Mixing Models on the Prediction of Turbulent Premixed and Stratified Combustion

Reynolds-Averaged Navier-Stokes calculations of turbulent premixed and stratified flames in two different configurations are performed to assess the effect of small-scale mixing rate models. The small-scale mixing rate is commonly known as the scalar dissipation rate. The Libby–Williams model involving delta functions is used to calculate the mean reaction rate. The classical model for the scalar dissipation rate underpredicts the mixing rate and gives poor agreement with mean values of velocity, temperature, and species mass fractions. Two other recently proposed dissipation rate models give good predictions at various stratification levels. Further analysis shows that despite adequate mean predictions, there are substantial differences in the mixing rates, fuel mass fraction variance, turbulence kinetic energy, and turbulence frequency predicted by these models. Additionally, the turbulence quantities predicted by the models show opposite trends with increasing stratification. Further Direct Numerical Simulation or experimental data is required for a thorough understanding of these differences.

The stellar mass fraction and baryon content of galaxy clusters and groups

[Abridged] The analysis of a sample of 52 clusters with precise and hypothesis-parsimonious measurements of mass shows that low mass clusters and groups are not simple scaled-down versions of their massive cousins in terms of stellar content: lighter clusters have more stars per unit cluster mass. The same analysis also shows that the stellar content of clusters and groups displays an intrinsic spread at a given cluster mass, i.e. clusters are not similar each other in the amount of stars they contain, not even at a fixed cluster mass. The stellar mass fraction depends on halo mass with (logarithmic) slope -0.55+/-0.08 and with 0.15+/-0.02 dex of intrinsic scatter at a fixed cluster mass. The intrinsic scatter at a fixed cluster mass we determine for gas mass fractions is smaller, 0.06+/-0.01 dex. The intrinsic scatter in both the stellar and gas mass fractions is a distinctive signature that the regions from which clusters and groups collected matter, a few tens of Mpc, are yet not representative, in terms of gas and baryon content, of the mean matter content of the Universe. The observed stellar mass fraction values are in marked disagreement with gasdynamics simulations with cooling and star formation of clusters and groups. We found the the baryon (gas+stellar) fraction is fairly constant for clusters and groups with 13.7<lg(mass)<15.0 solar masses and it is offset from the WMAP-derived value by about 6 sigmas. The offset could be related to the possible non universality of the baryon fraction pointed out by our measurements of the intrinsic scatter. Our analysis is the first that does not assume that clusters are identically equal at a given halo mass and it is also more accurate in many aspects. The data and code used for the stochastic computation are distributed with the paper.

Comparison of orthogonal liquid and gas chromatography–mass spectrometry platforms for the determination of amino acid concentrations in human plasma

Concentrations of amino acids in a human plasma pool were determined using four independent quantification methods. Orthogonal separation schemes (LC, GC, or GC×GC) and detection systems (triple quadrupole or time-of-flight mass spectrometry) are shown to demonstrate excellent consistency among platforms for quantifying 18 amino acids in NIST Standard Reference Material (SRM) 1950 Metabolites in Human Plasma using a well-characterized isotope dilution (ID) quantification method. Measured levels were consistent with reference values in plasma from the literature. Individual amino acid concentrations in plasma varied by over an order of magnitude ranging from 1.83 μg/g to 28.0 μg/g (7.78 μmol/L to 321 μmol/L). Average variability (coefficient of variation) between experimental amino acid concentrations (excluding cysteine) among all methods was 6.3%. Certified mass fraction values for amino acids in NIST SRM 1950 will be established from statistically weighted means of all experimental results.

Phase optimized skeletal mechanisms for engine simulations

Adaptive chemistry is based on the principle that instead of having one comprehensive model describing the entire range of chemical source term space (typically parameters related to temperature, pressure and species concentrations), a set of computationally simpler models are used, each describing a local region (in multidimensional space) or phases (in zero-dimensional space). In this work, an adaptive chemistry method based on phase optimized skeletal mechanisms (POSM) is applied to a 96 species n-heptane–isooctane mechanism within a two-zone zero-dimensional stochastic reactor model (SRM) for an spark-ignition (SI) Engine. Two models differing only in the extent of reduction in the phase mechanism, gave speed-up factors of 2.7 and 10. The novelty and emphasis of this study is the use of machine learning techniques to decide where the phases are and to produce a usable phase recognition. The combustion process is automatically divided up into an ‘optimal’ set of phases through machine learning clustering based on fuzzy logic predicates involving a necessity parameter (a measure giving an indication whether a species should be included in the mechanism or not). The mechanism of each phase is reduced from the full mechanism based on this necessity parameter with respect to the conditions of that phase. The algorithm to decide which phase the process is in is automatically determined by another machine learning method that produces decision trees. The decision tree is made up of asking whether the mass fraction values were above or below given values. Two POSM studies were done, a conservative POSM where the species in each phase are eliminated based on a necessity parameter threshold (speed-up 2.7) and a further reduced POSM where each phase was further reduced by hand (speed-up 10). The automated techniques of determining the phases and for creating the decision tree are very general and are not limited to the parameter choices of this paper. There is also no fundamental limit as to the size of the original detailed mechanism. The interfacing to include POSM in an application does not differ significantly from using the original detailed mechanism.

Preparation and Characterization of Standard Reference Material 1849 Infant/Adult Nutritional Formula

Standard Reference Material (SRM) 1849 Infant/Adult Nutritional Formula has been issued by the National Institute of Standards and Technology (NIST) as a replacement for SRM 1846 Infant Formula, issued in 1996. Extraction characteristics of SRM 1846 have changed over time, as have NIST's analytical capabilities. While certified mass fraction values were provided for five constituents in SRM 1846 (four vitamins plus iodine), certified mass fraction values for 43 constituents are provided in SRM 1849 (fatty acids, elements, and vitamins) and reference mass fraction values are provided for an additional 43 constituents including amino acids and nucleotides, making it the most extensively characterized food-matrix SRM available from NIST.

Large Eddy Simulation of a turbulent non-premixed propane-air reacting flame in a cylindrical combustor

Large Eddy Simulation (LES) is applied to investigate the turbulent non-premixed combustion flow, including species concentrations and temperature, in a cylindrical combustor. Gaseous propane (C 3H 8) is injected through a circular nozzle which is attached at the centre of the combustor inlet. Preheated air with a temperature of 773 K is supplied through the annulus surrounding of this fuel nozzle. In LES a spatial filtering is applied to the governing equations to separate the flow field into large-scale and small-scale eddies. The large-scale eddies which carry most of the turbulent energy are resolved explicitly, while the unresolved small-scale eddies are modelled using the Smagorinsky model with C s = 0.1 as well as dynamically calibrated C s . The filtered values of the species mass fraction, temperature and density, which are the functions of the mixture fraction (conserved scalar), are determined by integration over a beta probability density function ( β-PDF). The computational results are compared with those of the experimental investigation conducted by Nishida and Mukohara [1]. According to this experiment, the overall equivalence ratio of 0.6, which is calculated from the ratio of the air flow rate supplied to the combustion chamber to that of the stoichiometric reaction, is kept constant so that the turbulent combustion at the fuel nozzle exit starts under the fuel-rich conditions.

Bénard instabilities in a binary-liquid layer evaporating into an inert gas

A linear stability analysis is performed for a horizontal layer of a binary liquid of which solely the solute evaporates into an inert gas, the latter being assumed to be insoluble in the liquid. In particular, a water-ethanol system in contact with air is considered, with the evaporation of water being neglected (which can be justified for a certain humidity of the air). External constraints on the system are introduced by imposing fixed “ambient” mass fraction and temperature values at a certain effective distance above the free liquid–gas interface. The temperature is the same as at the bottom of the liquid layer, where, besides, a fixed mass fraction of the solute is presumed to be maintained. Proceeding from a (quasi-)stationary reference solution, neutral (monotonic) stability curves are calculated in terms of solutal/thermal Marangoni/Rayleigh numbers as functions of the wavenumber for different values of the ratio of the gas and liquid layer thicknesses. The results are also presented in terms of the critical values of the liquid layer thickness as a function of the thickness of the gas layer. The solutal and thermal Rayleigh and Marangoni effects are compared to one another. For a water–ethanol mixture of 10 wt.% ethanol, it appears that the solutal Marangoni effect is by far the most important instability mechanism. Furthermore, its global action can be described within a Pearson-like model, with an appropriately defined Biot number depending on the wavenumber. On the other hand, it is also shown that, if taken into account, water evaporation has only minor quantitative consequences upon the results for this predominant, solutal Marangoni mechanism.

Certification of NIST standard reference material 2389a, amino acids in 0.1 mol/L HCl—quantification by ID LC-MS/MS

An isotope-dilution liquid chromatography-tandem mass spectrometry (ID LC-MS/MS) measurement procedure was developed to accurately quantify amino acid concentrations in National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 2389a-amino acids in 0.1 mol/L hydrochloric acid. Seventeen amino acids were quantified using selected reaction monitoring on a triple quadrupole mass spectrometer. LC-MS/MS results were compared to gravimetric measurements from the preparation of SRM 2389a-a reference material developed at NIST and intended for use in intra-laboratory calibrations and quality control. Quantitative mass spectrometry results and gravimetric values were statistically combined into NIST-certified mass fraction values with associated uncertainty estimates. Coefficients of variation (CV) for the repeatability of the LC-MS/MS measurements among amino acids ranged from 0.33% to 2.7% with an average CV of 1.2%. Average relative expanded uncertainty of the certified values including Types A and B uncertainties was 3.5%. Mean accuracy of the LC-MS/MS measurements with gravimetric preparation values agreed to within |1.1|% for all amino acids. NIST SRM 2389a will be available for characterization of routine methods for amino acid analysis and serves as a standard for higher-order measurement traceability. This is the first time an ID LC-MS/MS methodology has been applied for quantifying amino acids in a NIST SRM material.

Marine mammal blubber reference and control materials for use in the determination of halogenated organic compounds and fatty acids

The National Institute of Standards and Technology (NIST) has a diverse collection of control materials derived from marine mammal blubber, fat, and serum. Standard Reference Material (SRM) 1945 Organics in Whale Blubber was recertified for polychlorinated biphenyl (PCB) congeners, organochlorine pesticides, and polybrominated diphenyl ether (PBDE) congeners. SRM 1945 has also been assigned mass fraction values for compounds not frequently determined in marine samples including toxaphene congeners, coplanar PCBs, and methoxylated PBDE congeners which are natural products. NIST also has assigned mass fraction values, as a result of interlaboratory comparison exercises, for PCB congeners, organochlorine pesticides, PBDE congeners, and fatty acids in six homogenate materials produced from marine mammal blubber or serum. The materials are available from NIST upon request; however, the supply is very limited for some of the materials. The materials include those obtained from pilot whale blubber (Homogenates III and IV), Blainville's beaked whale blubber (Homogenate VII), polar bear fat (Homogenate VI), and California sea lion serum (Marine Mammal Control Material-1 Serum) and blubber (Homogenate V).

An air-standard cycle and a thermodynamic perspective on operational limits of Ranque–Hilsh or vortex tubes

A Thermodynamic air-standard cycle was envisaged for Ranque–Hilsh (R–H) or Vortex Tubes to provide relevant Thermodynamic analysis and tools for setting operating limits according to the conservation laws of mass and energy, as well as the constraint of the Second Law of Thermodynamics. The study used an integral or control volume approach and resulted in establishing working equations for evaluating the performance of an R–H tube. The work proved that the coefficient of performance does not depend on the R–H tube operating mode, i.e., the same value is obtained independently if the R–H tube operates either as a heat pump or as a refrigeration device. It was also shown that the isentropic coefficient of performance displays optima values of cold and hot mass fractions for a given operating pressure ratio. Finally, the study was concluded by comparing the present analysis with some experimental data available in the literature for operating pressures ranging 2–11 atm.