P-V-T properties of methyl chloride at high temperatures and pressures

"The equation of state of a gas describes the relation between the three variables pressure, volume, and temperature. Many equations have been proposed which accurately describe the p-v-T relations of real gases (3,4,5,8,18,20, 26,31,32,39,51,58,70,74,90). Some of these are purely empirical while others are derived from the intermolecular properties. A knowledge of the equation of state is necessary for obtaining equilibrium properties of pure substances. The volumetric behavior of non-polar gases may be described by the application of the principle of corresponding states, which has been successful in predicting compressibility factors and second virial coefficients for both pure gases and binary gas mixtures (19, 24, 25, 34, 35, 49, 54, 59, 63, 66, 67, 71). Polar gases deviate considerably from the principle of corresponding states, and require different treatment. Two methods have been used in predicting the second virial coefficient of polar gases. The first method uses statistical mechanics and an intermolecular potential function based on a physical model. The second method is based on a hypothesis, first proposed by Eucken (21), that polar gases undergo partial association due to dipole interaction or to hydrogen bonding, and that this is responsible for their deviation from the principle of corresponding states. This method of interpretation was originally applied by Alexander and Lambert to their results on acetaldehyde (1), and later by others to interpret the second virial coefficients (10,23,30,33,46,47). In this investigation the first approach was used to analyze the experimental second virial coefficient data. In this investigation, the Kihara core model was used to represent the geometry of a polar molecule. A permanent point dipole was placed in the core and used to represent the polar contribution to the molecular pair force field. Pople's perturbation method (68) was used to obtain an expression for the second virial coefficient of a polar gas. Numerical methods were then used to evaluate the potential parameters for nine polar gases. Derived thermodynamic properties of methyl chloride were also calculated from the calculated B(T) values for the modified Kihara potential and compared with those calculated from the p-v-T data."--Introduction

Infrared properties of carbon stars in our Galaxy

In this study, we explore the characteristics of carbon stars within our Galaxy through a comprehensive analysis of observational data spanning visual and infrared (IR) bands. Leveraging datasets from IRAS, ISO, Akari, MSX, 2MASS, WISE, Gaia DR3, AAVSO, and the SIMBAD object database, we conduct a detailed comparison between the observational data and theoretical models. To facilitate this comparison, we introduce various IR two-color diagrams (2CDs), IR color-magnitude diagrams (CMDs), and spectral energy distributions (SEDs). We find that the CMDs, which utilize the latest distance and extinction data from Gaia DR3 for a substantial number of carbon stars, are very useful to distinguish carbon-rich asymptotic giant branch (CAGB) stars from extrinsic carbon stars that are not in the AGB phase. To enhance the accuracy of our analysis, we employ theoretical radiative transfer models for dust shells around CAGB stars. These theoretical dust shell models demonstrate a commendable ability to approximate the observations of CAGB stars across various SEDs, 2CDs, and CMDs. We present the infrared properties of known pulsating variables and explore the infrared variability of the sample stars by analyzing WISE photometric data spanning the last 14 yr. Additionally, we present a novel catalog of CAGB stars, offering enhanced reliability and a wealth of additional information.Comment: Accepted for publication in ApJS (26 pages; 18 figures

Coordination of Converter and Fuel Cell Controller

Abstract-Load-following fuel cell systems depend on control of reactant flow and regulation of DC bus voltage during load (current) drawn from them. To this end, we model and analyze the dynamics of a fuel cell system equipped with a compressor and a DC-DC converter. We then employ modelbased control techniques to tune two separate controllers for the compressor and the converter. We demonstrate that the lack of communication and coordination between the two controllers entails a severe tradeoff in achieving the stack and power output objectives. A coordinated controller is finally designed that manages the air and the electron flow control in an optimal way. Our results could be used as a benchmark of achievable fuel cell performance without hybridization

Liver transplantation for advanced hepatocellular carcinoma

There has been ongoing debate that the Milan criteria may be too strict that a significant number of patients who could benefit from liver transplantation (LT) might have been excluded. Based on this idea, various studies have been conducted to further expand the Milan criteria and give more HCC patients a chance of cure. In deceased donor LT (DDLT) setting, expansion of the criteria is relatively tempered because the results of LT for HCC should be comparable to those of patients with non-malignant indications. On the other hand, in living donor LT (LDLT) situation, liver grafts are not public resources. The acceptable target outcomes for LDLT might be much lower than those for DDLT. Patients with biologically favorable tumors might have excellent survivals after LT despite morphological advanced HCCs. Therefore, the significance and utility of biological tumor parameters for selecting suitable LT candidates have been increased to predict HCC recurrence after LT. Although there is no consensus regarding the use of prognostic biomarkers in LT selection criteria for HCC, the combination of conventional morphological parameters and new promising biomarkers could help us refine and expand the LT criteria for HCC in the near future