Four-component Mixture Research Articles

Investigation of Fuel Briquettes Properties Using Wastes of Mineral Wool Production

One of the most common melt production units in mineral wool product manufacture is a shaft type unit - cupola furnace. The process feature of raw material preparation is a screening process of both solid fuel (coke) and mineral matter (gabbro, limestone). At that quite large amount of fine fraction materials is generated, which are impossible to be used in a cupola furnace considering severe fractional makeup requirements for the charge materials. The usage of fine fraction is possible with a briquetting process. Four-component mixture involving mineral matter (gabbro), coke fines, binding agents and water was used for a trial lot briquette formation. The binding agent most efficient for their formation was determined experimentally. It was established that drying time sufficient to get a strong product comprises 10 minutes at the temperature of 100 °С. STA 449 F3 Jupiter unit was used for thermogravimetric and differential scanning calorimetric analyses and coke fine samples were examined.

Vibration Spectroscopy of Complex Formation in Aqueous Solutions of Isopropanol

The formation of molecular complexes in isopropanol-water solutions is studied by means of vibrational spectroscopy techniques. The ATR FTIR spectra of solutions with different mixing ratios are detected. The multivariate curve resolution of the experimental data set shows that the investigated solution could be treated as a four-component mixture, which contains pure isopropanol, pure water, and two molecular complexes.

Development of a reaction/distillation matrix for systematic generation of sequences in a single two component reaction-separation case study

Studies on simultaneous synthesis of the reaction-separation processes are limited. The initial step is choosing a method to generate all possible arrangements. In this work, the Separation matrix algorithm previously developed by the authors has been expanded to include the reaction part of the process to form a Reaction/Distillation matrix.In order to achieve a comprehensive algorithm, initially all feasible matrices have been analyzed to find common points among non-synthesizable matrices. The ability of new matrix to include a broad selection of flowsheets has then been investigated. A single two-component reaction, is assumed to prevail within a four-component mixture, the fourth being the initially nonexistent reaction product. A systematic approach is presented to determine a large selection of sequences for a four-component system including three distillation columns (simple or complex) and a reactor. A practical case study of the isomerization of n-Butane has been analyzed using the procedure developed here.

SELECTING THE OPTIMUM SCHEME OF THE SEPARATION OF HYDROCARBON GASES BY DISTILLATION

The heat costs in distillation columns were determined for the purpose of separating a four-component gas mixture in gas fractionators with various component selection sequences. A method for selecting the optimal scheme was developed. It is based on the concept of “internal energy saving” upon rectification. Internal energy saving means multiple steam operation on the plates of a distillation column, namely, its condensation on each plate with the release of the heat of condensation, which is used for the evaporation of the liquid entering the plate to obtain a new steam composition. It was shown that when binary and three-component mixtures are separated and products of equal purity are obtained, the heat costs are related to the internal energy saving. The calculation of the internal energy saving in a three-column system for the separation of a four-component mixture was carried out. The calculation confirms that, as the internal energy saving increases and, accordingly, the average internal energy saving in the system of columns increases, the total heat consumption is reduced. The results of calculating three separation schemes of the four-component mixture were compared using the program Aspen Plus with different methods for describing the phase equilibrium (NRTL, Peng-Robinson, Chao-Seader) was carried out. It was shown that the calculations with the use of Peng-Robinson and Chao-Seader methods match.

Optical and X-ray studies of a four component cyano liquid crystal mixture: Comparison of properties with that of a similar mixture

Optical and X-ray studies have been conducted on a four component liquid crystal mixture (code name 2013) with cyano–end groups in all the four components and a lateral substitution of fluorine atom in one of them. The variations in the optical birefringence with temperature, have been investigated and the thermal dependence of polarisability anisotropy and orientational order parameter have been evaluated. X-ray studies have been conducted to determine the effective molecular characteristics such as apparent molecular length and inter molecular distance and their variations with temperature. From nature of molecular alignment as envisaged from X-ray photographs the order parameter variation with temperature has been determined and compared with macroscopic order parameter variation as determined from birefringence studies. The results have been compared with these obtained for another structurally similar four-component liquid crystal mixture (code name 2014) with isothiocyanato end group in place of cyano.

Combined Experimental, Theoretical, and Molecular Simulation Approach for the Description of the Fluid-Phase Behavior of Hydrocarbon Mixtures within Shale Rocks

An experimental, theoretical, and molecular simulation consolidated framework for the efficient characterization of the adsorption and fluid-phase behavior of multi-component hydrocarbon mixtures within tight shale rocks is presented. Fluid molecules are described by means of a top-down coarse-grained model where simple Mie intermolecular potentials are parametrized by means of the statistical associating fluid theory. A four-component (methane, pentane, decane, naphthalene) mixture is used as a surrogate model with a composition representative of commonly encountered shale oils. Shales are modeled as a hierarchical network of nanoporous slits in contact with a mesoporous region. The rock model is informed by the characterization of four distinct and representative shale core samples through nitrogen adsorption, thermogravimetric analysis, and contact angle measurements. Experimental results suggest the consideration of two types of pore surfaces: a carbonaceous wall representing the kerogen regions of a ...

FRET Detects the Size of Nanodomains for Coexisting Liquid-Disordered and Liquid-Ordered Phases

Biomembranes with as few as three lipid components can form coexisting liquid-disordered (Ld) and liquid-ordered (Lo) phases. In the coexistence region of Ld and Lo phases, the lipid mixtures 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)/1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/chol or brain sphingomyelin (bSM)/DOPC/chol form micron-scale domains that are easily visualized with light microscopy. Although large domains are not observed in the mixtures DSPC/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/chol and bSM/POPC/chol, lateral heterogeneity is nevertheless detected using techniques with nanometer-scale spatial resolution. We propose a simple and accessible method to measure domain sizes below optical resolution (∼200 nm). We measured nanodomain size for the latter two mixtures by combining experimental Förster resonance energy transfer data with a Monte-Carlo-based analysis. We found a domain radius of 7.5−10 nm for DSPC/POPC/chol, similar to values obtained previously by neutron scattering, and ∼5 nm for bSM/POPC/chol, slightly smaller than measurable by neutron scattering. These analyses also detect the domain-size transition that is observed by fluorescence microscopy in the four-component lipid mixture bSM/DOPC/POPC/chol. Accurate measurements of fluorescent-probe partition coefficients are especially important for the analysis; therefore, we exploit three different methods to measure the partition coefficient of fluorescent molecules between Ld and Lo phases.

Thermodynamic Work of Separation in a Cascade System in Processing a Multicomponent Mixture

The possibility of calculating thermodynamic work of separation W T,K for a complex of cascades consisting of earlier described stages of equilibrium separation with semipermeable plungers is illustrated by the processing of a four-component mixture. It is found that work W T,K can be considered as sum ΣW T,K mk, where W T,K mk corresponds to selected pairs of components (m, k) in a multicomponent mixture. The proposed procedure for calculating W T,K is spread into combinations of 8, 16, or even more components, and into extraction and chromatographic systems of fractioning.

The construction of [formula omitted]- and [formula omitted]-optimal designs for mixture experiments with linear constraints on the components

Mixture experiments in which linear constraints are imposed on the components of the mixture are used extensively in practice. The problem of constructing designs which are in some sense optimal for this experimental setting is not straightforward. More specifically, the design space is a polytope embedded in a regular simplex. In the present paper, a new approach to the problem, which builds on the fact that points in the polytope can be represented as convex combinations of the vertices of that polytope, is introduced. Some theory underpinning this idea and rooted in the notion of barycentric coordinates is developed and algorithms for the construction of exact and approximate D- and I-optimal designs for the Scheffé model are delineated. The methodology is illustrated by means of examples involving three- and four-component mixtures.

Influence of Physiological Gastrointestinal Surfactant Ratio on the Equilibrium Solubility of BCS Class II Drugs Investigated Using a Four Component Mixture Design.

The absorption of poorly water-soluble drugs is influenced by the luminal gastrointestinal fluid content and composition, which control solubility. Simulated intestinal fluids have been introduced into dissolution testing including endogenous amphiphiles and digested lipids at physiological levels; however, in vivo individual variation exists in the concentrations of these components, which will alter drug absorption through an effect on solubility. The use of a factorial design of experiment and varying media by introducing different levels of bile, lecithin, and digested lipids has been previously reported, but here we investigate the solubility variation of poorly soluble drugs through more complex biorelevant amphiphile interactions. A four-component mixture design was conducted to understand the solubilization capacity and interactions of bile salt, lecithin, oleate, and monoglyceride with a constant total concentration (11.7 mM) but varying molar ratios. The equilibrium solubility of seven low solubility acidic (zafirlukast), basic (aprepitant, carvedilol), and neutral (fenofibrate, felodipine, griseofulvin, and spironolactone) drugs was investigated. Solubility results are comparable with literature values and also our own previously published design of experiment studies. Results indicate that solubilization is not a sum accumulation of individual amphiphile concentrations, but a drug specific effect through interactions of mixed amphiphile compositions with the drug. This is probably due to a combined interaction of drug characteristics; for example, lipophilicity, molecular shape, and ionization with amphiphile components, which can generate specific drug–micelle affinities. The proportion of each component can have a remarkable influence on solubility with, in some cases, the highest and lowest points close to each other. A single-point solubility measurement in a fixed composition simulated media or human intestinal fluid sample will therefore provide a value without knowledge of the surrounding solubility topography meaning that variability may be overlooked. This study has demonstrated how the amphiphile ratios influence drug solubility and highlights the importance of the envelope of physiological variation when simulating in vivo drug behavior.

Characterization of a biomethane-like synthetic gas mixture through accurate density measurements from (240 to 350) K and pressures up to 14 MPa

In this work the thermodynamic behavior of a synthetic four-component biomethane-like mixture, composed mainly of methane (96.48%), with small amounts of carbon dioxide (2.00%), nitrogen (1.50%), and traces of oxygen (0.02%), is studied using accurate (p,ρ,T) experimental data. Two mixtures of identical nominal compositions were prepared by the gravimetric method at the Spanish National Metrology Institute (Centro Español de Metrología, CEM) and at the Slovak National Metrology Institute (Slovenský Metrologický Ústav, SMÚ). The composition was double checked by Gas Chromatography, at both NMI and at the beginning and end of the measurements. An additional test of the consistency of the given compositions was performed by measuring the density of both mixtures at selected points, with two different techniques, in two different laboratories. Accurate density measurements have been taken over a wide temperature range, from (240 to 350) K, and pressures up to 14MPa, using a single-sinker densimeter with magnetic suspension coupling. Experimental data are compared with the densities calculated with the GERG-2008 and AGA8-DC92 equations of state. Deviations between experimental and GERG-2008-estimated densities are within a ±0.03% band at all temperatures, which shows the outstanding performance of the current reference equation for natural gases when describing a biomethane-like mixture. Deviations between experimental and AGA-8-estimated densities are higher than 0.04% at 250K for pressures greater than 10MPa and also at 240K for pressures higher than 9MPa. This work is part of the research project ‘Metrology for Biogas’ supported by the European Metrology Research Program.

Line Tension Controls Liquid-Disordered + Liquid-Ordered Domain Size Transition in Lipid Bilayers

To better understand animal cell plasma membranes, we studied simplified models, namely four-component lipid bilayer mixtures. Here we describe the domain size transition in the region of coexisting liquid-disordered (Ld) + liquid-ordered (Lo) phases. This transition occurs abruptly in composition space with domains increasing in size by two orders of magnitude, from tens of nanometers to microns. We measured the line tension between coexisting Ld and Lo domains close to the domain size transition for a variety of lipid mixtures, finding that in every case the transition occurs at a line tension of ∼0.3 pN. A computational model incorporating line tension and dipole repulsion indicated that even small changes in line tension can result in domains growing in size by several orders of magnitude, consistent with experimental observations. We find that other properties of the coexisting Ld and Lo phases do not change significantly in the vicinity of the abrupt domain size transition.

Breaking of SU(4) symmetry and interplay between strongly correlated phases in the Hubbard model

We study the thermodynamic properties of four-component fermionic mixtures described by the Hubbard model using the dynamical mean-field-theory approach. Special attention is given to the system with SU(4)-symmetric interactions at half filling, where we analyze equilibrium many-body phases and their coexistence regions at nonzero temperature for the case of simple cubic lattice geometry. We also determine the evolution of observables in low-temperature phases while lowering the symmetry of the Hamiltonian towards the two-band Hubbard model. This is achieved by varying interflavor interactions or by introducing the spin-flip term (Hund's coupling). By calculating the entropy for different symmetries of the model, we determine the optimal regimes for approaching the studied phases in experiments with ultracold alkali and alkaline-earth-like atoms in optical lattices.

Effects of Ester and Ether Linkage in Phospholipids on Ld + Lo Domain Size Transition for a Four-Component Lipid Bilayer Mixture

Effects of Ester and Ether Linkage in Phospholipids on Ld + Lo Domain Size Transition for a Four-Component Lipid Bilayer Mixture

Performance of legume-based annual forage crops in three semi-arid Mediterranean environments

Legume-based annual forages could be pivotal for the sustainable intensification of forage production in drought-prone Mediterranean cereal-livestock systems. This study aimed to optimise the composition of these crops for three climatically contrasting areas. Four legumes (field pea of semi-dwarf and tall type; Narbon vetch; common vetch) and two cereals (oat; triticale) were grown in three autumn-sown sites (Sassari, Italy; Sétif, Algeria; Marchouch, Morocco) for 2 years as pure stands and legume-cereal binary and four-component mixtures. We assessed dry matter yield, weed content and farmers’ acceptability of the crops, and legume content and Land Equivalent Ratio of the mixtures. Legumes’ competitive disadvantage ranged from very high in Sétif to nearly nil in Sassari. Pea- and common vetch-based mixtures out-performed Narbon vetch-based ones in terms of yield, legume content and farmers’ acceptability. The tall pea, featuring greatest competitive ability against cereals, maximised the yield and legume content of legume-cereal crops. Vetch-cereal mixtures exhibited lower weed content than the average of the components’ pure stands. Oat monoculture was top-yielding but modestly appreciated by farmers. Pea provided the only legume monoculture combining good yielding ability and high farmers’ appreciation. Greater species diversity as provided by complex mixtures did not display any production advantage over binary mixtures.

Dynamics of the density of lawn grass and herbage on loamy and sandy soils

Conducted research on the dynamics of the density of single-species and mixed grass crops on sod-podzolic soils of the Ryazan region. The estimation of the density of turf grass stands in the years 2012-2014 studies found that the highest density had a single-species crops: Kentucky bluegrass, red fescue, bent grass selenobrachys, and among mixed crops - a three-component grass mixture (red fescue, Kentucky bluegrass, bent grass selenobrachys) and four-component mixture (selenobrachys bent grass, red fescue, Kentucky bluegrass, red fescue). The lowest density of planting was installed at the perennial ryegrass in the second and third years and three-component grass mixture (red fescue, sheep's fescue, perennial ryegrass) in the third year of life of grass. The trend of higher density turf grass stands revealed in experiment 1 for loamy soils compared to sandy loam.

The effect of capillary condensation on the phase behavior of hydrocarbon mixtures in the organic nanopores

ABSTRACTIn nanoscale pores, the adsorption of gas is a multilayer adsorption process, and the conventional Langmuir model is no longer valid. In particular for the unconventional gas condensate reservoir, the adsorbed gas will become condensate once the pressure is above the critical condensate pressure at pore scale. In this study, considering the effect of adsorption (wetting) film, the multicomponent Kelvin equation is modified to computing the isotherm of capillary condensation. Then it is coupled with the multispace adsorption model and Peng-Robinson equation of state to investigate and represent the phase behavior of hydrocarbons in organic nanopores. Then, a prediction process for the behavior of a four-component mixture of methane, n-butane, n-pentane, n-hexane are performed. The actual Marcellus shale gas is also used to examine the performance of this model.

ANALYSIS OF FORMULATION EFFECTS IN THE DISSOLUTION OF KETOPROFEN PELLETS

In this work the effects of citric acid and two common fillers, lactose (soluble) and tricalcium phosphate (insoluble) are examined on the release profiles from pellets, using ketoprofen as a model drug with pHdependent solubility. Also studies were conducted on dependence of these profiles on the specific surface area, bulk density, apparent density, porosity and porosity parameters (pore size distribution, total pore surface area, mean pore diameter and pore shape), as determined by mercury intrusion porosimetry. Pellets were prepared by the extrusion-spheronization method. Four different formulations were considered: two ternary mixtures of ketoprofen (I), lactose (L) or tricalcium phosphate (P) and microcel (M) in the relative proportions 2:3:5 (ILM or IPM) and two four-component mixtures of the same components plus 5% citric acid (C) in the relative proportions 2:2.5:0.5:5 (CILM or CIPM). Pellets with high porosity and total pore sur face area but small median pore diameter ( t r icalcium phosphate pellets IPM) are found to produce similar dissolution results to those of low porosity and low total pore surface area, but having a high median pore diameter ( lactose pellets I LM) , ir respect ive of the solubility of excipients. Addition of citric acid causes a delay in the initial dissolution for both formulations. During dissolution, however, citric acid reduces the median pore diameter of lactose-based pellets. In contrast, in tricalcium phosphate/ cit r ic acid pellet s (CIPM) , this parameter increases considerably dur ing dissolut ion, when compared to the IPM formulat ion. These findings may just ify the cont rast ing dissolut ion behaviors of CIPM and CILM (lactose/citric acid) pellets, after their common behavior in the initial stages, and show that porosity and its related parameters, along with physical properties of excipients such as solubility, density and specific surface area, are helpful to predict pellet behavior in drug release profiles.

A Bivariate Mixture Model for Natural Antibody Levels to Human Papillomavirus Types 16 and 18: Baseline Estimates for Monitoring the Herd Effects of Immunization.

Post-vaccine monitoring programs for human papillomavirus (HPV) have been introduced in many countries, but HPV serology is still an underutilized tool, partly owing to the weak antibody response to HPV infection. Changes in antibody levels among non-vaccinated individuals could be employed to monitor herd effects of immunization against HPV vaccine types 16 and 18, but inference requires an appropriate statistical model. The authors developed a four-component bivariate mixture model for jointly estimating vaccine-type seroprevalence from correlated antibody responses against HPV16 and -18 infections. This model takes account of the correlation between HPV16 and -18 antibody concentrations within subjects, caused e.g. by heterogeneity in exposure level and immune response. The model was fitted to HPV16 and -18 antibody concentrations as measured by a multiplex immunoassay in a large serological survey (3,875 females) carried out in the Netherlands in 2006/2007, before the introduction of mass immunization. Parameters were estimated by Bayesian analysis. We used the deviance information criterion for model selection; performance of the preferred model was assessed through simulation. Our analysis uncovered elevated antibody concentrations in doubly as compared to singly seropositive individuals, and a strong clustering of HPV16 and -18 seropositivity, particularly around the age of sexual debut. The bivariate model resulted in a more reliable classification of singly and doubly seropositive individuals than achieved by a combination of two univariate models, and suggested a higher pre-vaccine HPV16 seroprevalence than previously estimated. The bivariate mixture model provides valuable baseline estimates of vaccine-type seroprevalence and may prove useful in seroepidemiologic assessment of the herd effects of HPV vaccination.

Orbital magnetism of ultracold fermionic gases in a lattice: Dynamical mean-field approach

We study finite-temperature properties of ultracold four-component mixtures of alkaline-earth-like atoms in optical lattices that can be effectively described by the two-band spin-$1/2$ Hubbard model including the Hund's exchange coupling term. Our main goal is to investigate the effect of exchange interactions on finite-temperature magnetic phases for a wide range of lattice fillings. We use the dynamical mean-field theory approach and its real-space generalization to obtain finite-temperature phase diagrams including transitions to magnetically-ordered phases. It allows to determine optimal experimental regimes for approaching long-range ferromagnetic ordering in ultracold gases. We also calculate the entropy in the vicinity of magnetically-ordered phases, which provides quantitative predictions for on-going and future experiments aiming at approaching and studying long-range ordered states in optical lattices.