Reference Correlation for the Viscosity of Nitrogen from the Triple Point to 1000 K and Pressures up to 2200 MPa.

We present a new wide-ranging correlation for the viscosity of nitrogen based on critically evaluated experimental data as well as ab-initio calculations. The correlation is designed to be used with densities from an existing equation of state, which is valid from the triple point to 1000 K, at pressures up to 2200 MPa. The estimated uncertainty (at the 95% confidence level) for the viscosity varies depending on the temperature and pressure, from a low of 0.2% in the dilute-gas range near room temperature, to 4% for the liquid phase at pressures from saturation up to 34 MPa, and maximum of 8% in the supercritical region at pressures above 650 MPa. Extensive comparisons with experimental data are provided. Supplementary Information: The online version contains supplementary material available at 10.1007/s10765-024-03440-1.

Fundamental Equation of State for Fluid Tetrahydrofuran.

An empirical fundamental equation of state in terms of the Helmholtz energy for tetrahydrofuran is presented. In the validity range from the triple-point temperature up to 550 K and pressures up to 600 MPa, the equation of state enables the calculation of all thermodynamic properties in the liquid, vapor, and super-critical regions including saturation states. Based on an extensive literature review, experimental data are represented within their experimental uncertainty. In the homogeneous liquid phase at atmospheric pressure, the uncertainty in density is 0.015 %, speed of sound is represented with an uncertainty of 0.03 %, and isobaric heat capacity has an uncertainty of 0.4 %. Isobaric heat capacities in the homogeneous vapor phase are described with an uncertainty of 0.2 %. Higher uncertainties occur above atmospheric pressure for all homogeneous properties. Depending on the temperature range, vapor pressure can be calculated with an uncertainty from 0.02 % to 3 %. The extrapolation behavior is evaluated, showing reasonable extrapolation behavior towards extreme conditions. Supplementary Information: The online version contains supplementary material available at 10.1007/s10765-023-03258-3.

An Analysis of the Critical Region of Multiparameter Equations of State.

In this work, two classes of defects with multiparameter equations of state are investigated. In the first, it is shown that the critical point provided by equation of state developers often does not exactly meet the criticality conditions based on the first two density derivatives of the pressure being zero at the critical point. Based on the more accurate locations of the critical points given in the first part, the scaling of the densities along the binodal and spinodal in the critical region are investigated, and we find that the vast majority of equations have reasonable behavior but a few do not.

Antibiotic Use and Respiratory Viral PCR Testing Among Pediatric Patients With Nosocomial Fever.

Objective Pediatric patients admitted to the hospital often develop fevers during their inpatient stay, and many children are empirically started on antibiotics. The utility of respiratory viral panel (RVP) polymerase chain reaction (PCR) testing in the evaluation of nosocomial fevers in admitted patients is unclear. We sought to evaluate whether RVP testing is associated with the use of antibiotics among inpatient pediatric patients. Patients and methods We conducted a retrospective chart review of children admitted from November 2015 to June 2018. We included all patients who developed fever 48 hours or more after admission to the hospital and who were not already receiving treatment for a presumed infection (on antibiotics). Results Among 671 patients, there were 833 inpatient febrile episodes. The mean age of children was 6.3 years old, and 57.1% were boys. Out of 99 RVP samples analyzed, 22 were positive (22.2%). Antibiotics were started in 27.8% while 33.5% of patients were already on antibiotics. On multivariate logistic regression, having an RVP sent was significantly associated with increased initiation of antibiotics (aOR 95% CI 1.18-14.18, p=0.03). Furthermore, those with a positive RVP had a shorter course of antibiotics compared to those with a negative RVP (mean 6.8 vs 11.3 days, p=0.019). Conclusions Children with positive RVP had decreased antibiotic exposure compared to those with negative RVP results. RVP testing may be used to promote antibiotic stewardship among hospitalized children.

The NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids.

The NIST REFPROP software program is a powerful tool for calculating thermophysical properties of industrially important fluids, and this manuscript describes the models implemented in, and features of, this software. REFPROP implements the most accurate models available for selected pure fluids and their mixtures that are valid over the entire fluid range including gas, liquid, and supercritical states, with the goal of uncertainties approaching the level of the underlying experimental data. The equations of state for thermodynamic properties are primarily of the Helmholtz energy form; a variety of models are implemented for the transport properties. We document the models for the 147 fluids included in the current version. A graphical user interface generates tables and provides extensive plotting capabilities. Properties can also be accessed through third-party apps or user-written code via the core property subroutines compiled into a shared library. REFPROP disseminates international standards in both the natural gas and refrigeration industries, as well as standards for water/steam.

Revised Standardized Equation for Hydrogen Gas Densities for Fuel Consumption Applications.

An equation for the density of hydrogen gas has been developed that agrees with the current standard to within 0.01 % from 220 K to 1000 K with pressures up to 70 MPa, to within 0.01 % from 255 K to 1000 K with pressures to 120 MPa, and to within 0.1 % from 200 K to 1000 K up to 200 MPa. The equation is a truncated virial-type equation based on pressure and temperature dependent terms. The density uncertainty for this equation is the same as the current standard and is estimated to be 0.04 % (combined uncertainty with a coverage factor of 2) between 250 K and 450 K for all pressures, and 0.1 % for lower temperatures. Comparisons are presented with experimental data and with the full equation of state.

Density measurements of compressed-liquid dimethyl ether + pentane mixtures.

Compressed-liquid densities of three compositions of the binary mixture dimethyl ether (CAS No. 115-10-6) + pentane (CAS No. 109-66-0) have been measured with a vibrating U-tube densimeter. Measurements were made at temperatures from 270 K to 390 K with pressures from 1.0 MPa to 50 MPa. The overall combined uncertainty (k=2) of the density data is 0.81 kg·m-3. Data presented here have been used to improve a previously formulated Helmholtz energy based mixture model. The newly derived parameters are given.

The insulin and IGF1 receptor kinase domains are functional dimers in the activated state.

The insulin receptor (IR) and insulin-like growth factor-1 receptor (IGF1R) are highly related receptor tyrosine kinases with a disulfide-linked homodimeric architecture. Ligand binding to the receptor ectodomain triggers tyrosine autophosphorylation of the cytoplasmic domains, which stimulates catalytic activity and creates recruitment sites for downstream signalling proteins. Whether the two phosphorylated tyrosine kinase domains within the receptor dimer function independently or cooperatively to phosphorylate protein substrates is not known. Here we provide crystallographic, biophysical and biochemical evidence demonstrating that the phosphorylated kinase domains of IR and IGF1R form a specific dimeric arrangement involving an exchange of the juxtamembrane region proximal to the kinase domain. In this dimer, the active position of α-helix C in the kinase N lobe is stabilized, which promotes downstream substrate phosphorylation. These studies afford a novel strategy for the design of small-molecule IR agonists as potential therapeutic agents for type 2 diabetes.

ThermoData Engine (TDE): software implementation of the dynamic data evaluation concept. 2. Equations of state on demand and dynamic updates over the web.

ThermoData Engine (TDE) is the first full-scale software implementation of the dynamic data evaluation concept, as reported recently in this journal. The present paper describes two major software enhancements to TDE: (1) generation of equation of state (EOS) representations on demand and (2) establishment of a dynamically updated experimental data resource for use in the critical evaluation process. Four EOS formulations have been implemented in TDE for on-demand evaluation: the volume translated Peng-Robinson, modified Sanchez-Lacombe, PC-SAFT, and Span Wagner EOS. The equations are fully described with their general application. The class structure of the program is described with particular emphasis on special features required to implement an equation, such as an EOS, that represents multiple properties simultaneously. Full implementation of the dynamic data evaluation concept requires that evaluations be based on an up-to-date "body of knowledge" or, in the case of TDE, an up-to-date collection of experimental results. A method to provide updates through the World Wide Web is described that meets the challenges of maintenance of data integrity with full traceability. Directions for future enhancements are outlined.