Different Head Group Dependence on The Lipid Thermodynamic Property of Myelin Basic Protein in the Lipid Monolayer

The interaction between the role of 18.5 KDa myelin basic protein (MBP) isoform and phospholipids has been thought to maintain the stability and compactness of the myelin sheath structure. In this study, we describe the statistical thermodynamic theory of different concentrations’ effects on MBP in the major myelin lipid (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE)，and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS)) monolayers at the air/subphase interface via Langmuir-Blodgett (LB) technique. A simple statistical mechanical theory is established that predicts the interaction between proteins and phosphate head groups at low surface pressures and the second virial coefficient dependences for the PC, PE, and PS head groups are illustrated. In addition, the surface pressure(π)-mean molecular area(mma) curves were also analyzed using two-dimensional virial equation of state (2D-VES). The positively charged showed that MBP may integrate into different lipid monolayers via hydrophobic and electrostatic interactions, which was found to be consistent with AFM observations of domain and aggregate structures as well as with changes in the surface morphology induced by MBP. These analyses pertaining to membrane structure will provide better insight into membrane modeling systems, especially the interaction between membrane molecules.

Methodology for constructing the equation of state and thermodynamic tables for a new generation refrigerant

A unified fundamental equation of state 2,3,3,3-tetrafluoropropene (R1234yf) has been developed, a fourth-generation ozone safe refrigerant, and a method for constructing the equation has been proposed. In the gas region, this equation transforms into the virial equation of state, and in the vicinity of the critical point it satisfies the requirements of the modern large-scale theory of critical phenomena and transforms into the Widom scale equation. On the basis of a single fundamental equation of state in accordance with GOST R 8.614-2018, standard reference data (GSSSD 380-2020) on the density, enthalpy, isobaric heat capacity, isochoric heat capacity, entropy and sound velocity of R1234yf in the temperature range from 230 K to 420 K and pressures from 0.1 MPa to 20 MPa. A comparison of the calculated values of equilibrium properties with the most reliable experimental data obtained in the famous of the world, and tabular data obtained on the basis of the known fundamental equations of state R1234yf. Uncertainties of tabulated data for saturated vapor pressure, density, enthalpy, isobaric heat capacity, isochoric heat capacity, entropy and speed of sound of 2,3,3,3-tetrafluoropropene are estimated – standard relative uncertainties by type A, B, total standard relative and expanded uncertainties. The results obtained in the work show that the proposed unified fundamental equation of state adequately describes the equilibrium properties of R1234yf in the range of state parameters stated above.

Snowpack-stored atmospheric surface-active contaminants traced with snowmelt water surface film rheology

The aim of the study was to quantify the adsorptive and thermo-elastic properties of snowmelt water surface films and their spatial-temporal evolution with snowpack structure characteristics and the entrapped surface-active organic composition. Surface pressure–area (π-A)T isotherms, surface pressure-temperature (π-T)A isochors, and stress–relaxation (π-t) measurements were performed using a Langmuir trough system on snowmelt water samples collected in a large-scale field studies performed at several industrialized and rural Tricity (Gdansk, Poland) areas at various environmental conditions and subsequent stages of the snowpack melting progress. Since the snow-melted water composition and concentrations of surface active organic matter fractions therein are largely undetermined, the force-area isotherm scaling formalisms (2D virial equation and 2D film scaling theory of polymeric films) were adapted to the complex mixture of surfactants. The surface film parameters and their spatial and temporal evolution turned out to be unequivocally related to principal signatures of the film-forming materials: surfactant concentrations (π, Alim), surface activity (Eisoth, |E|), film material solubility (R), surface material miscibility and 2D architecture complexity (y, βs), molecular thermal mobility (πk), and a timescale of the relaxation processes within the film (τi, |E|). Moreover, the parameters appeared to be correlated with snowpack structure characteristics (snow density ρ, specific snow area SSA, snow cover thickness), sample age time, and anthropogenic atmospheric contamination pressure source locations. In particular, Eisoth was found to be related to ρ and SSA, while R correlated with the solubility of film-forming organics which turned out to be long-chain fatty acids; similarly, spatial profiles of Eisoth revealed the peak values next to the areas being under a severe anthropogenic air pollution pressure. Snowmelt water films stand for a structurally heterogeneous (y > 10) interfacial system where several transition processes of differentiated time-scales (relaxation times from 7 to 63 s) took place leading to the apparent surface viscoelasticity. To sum up, the established surface rheological parameters could serve as novel indicators, based solely on physical attributes, allowing to follow the snowpack evolution, and its melting polymorphism in order to test or improve the existing snow-entrapped organics release models based on chemical analyses. The cross-correlation functional dependences of practical value remain to be established on the larger data set.

Thermodynamics-Inspired Macroscopic States of Bounded Swarms

The collective behavior of swarms is extremely difficult to estimate or predict, even when the local agent rules are known and simple. The presented work seeks to leverage the similarities between fluids and swarm systems to generate a thermodynamics-inspired characterization of the collective behavior of robotic swarms. While prior works have borrowed tools from fluid dynamics to design swarming behaviors, they have usually avoided the task of generating a fluids-inspired macroscopic state (or macrostate) description of the swarm. This work will bridge the gap by seeking to answer the following question: is it possible to generate a small set of thermodynamics-inspired macroscopic properties that may later be used to quantify all possible collective behaviors of swarm systems? In this paper, we present three macroscopic properties analogous to pressure, temperature, and density of a gas to describe the behavior of a swarm that is governed by only attractive and repulsive agent interactions. These properties are made to satisfy an equation similar to the ideal gas law and also generalized to satisfy the virial equation of state for real gases. Finally, we investigate how swarm specifications such as density and average agent velocity affect the system macrostate.