Dilute Model Research Articles

Pre-Screening of 1-Ethyl-3-Methylimidazolium Tetrachloroaluminate and Influence of Diethylene Glycol on the Ionic Liquid in Separation of Molecular Solutes: Activity Coefficients at Infinite Dilution and Cosmo-Sac Modelling

Pre-Screening of 1-Ethyl-3-Methylimidazolium Tetrachloroaluminate and Influence of Diethylene Glycol on the Ionic Liquid in Separation of Molecular Solutes: Activity Coefficients at Infinite Dilution and Cosmo-Sac Modelling

Thermodynamic features of the 1D dilute Ising model in the external magnetic field

We consider the effects of the magnetic field on the frustrated phase states of the dilute Ising chain, especially, the behavior of the magnetic entropy change and the isentropic dependence of the temperature on the magnetic field, which are the key parameters of the magnetocaloric effect. The found temperature dependences of entropy demonstrate the nonequivalence of frustrated phases in the antiferromagnetic and ferromagnetic cases. In the antiferromagnetic case, the nonzero magnetic field at certain parameters causes a charge ordering for nonmagnetic impurities at a half-filling, while in the ferromagnetic case, the magnetic field reduces the frustration of the ground state only partially. It is also shown, that impurities radically change the magnetic Grüneisen parameter in comparison with the case of a pure Ising chain.

Critical behaviour of loop models on causal triangulations

We introduce a dense and a dilute loop model on causal dynamical triangulations. Both models are characterised by a geometric coupling constant g and a loop parameter α in such a way that the purely geometric causal triangulation model is recovered for α = 1. We show that the dense loop model can be mapped to a solvable planar tree model, whose partition function we compute explicitly and use to determine the critical behaviour of the loop model. The dilute loop model can likewise be mapped to a planar tree model; however, a closed-form expression for the corresponding partition function is not obtainable using the standard methods employed in the dense case. Instead, we derive bounds on the critical coupling g c and apply transfer matrix techniques to examine the critical behaviour for α small.

QSPR modeling of selectivity at infinite dilution of ionic liquids

The intelligent choice of extractants and entrainers can improve current mixture separation techniques allowing better efficiency and sustainability of chemical processes that are both used in industry and laboratory practice. The most promising approach is a straightforward comparison of selectivity at infinite dilution between potential candidates. However, selectivity at infinite dilution values are rarely available for most compounds so a theoretical estimation is highly desired. In this study, we suggest a Quantitative Structure–Property Relationship (QSPR) approach to the modelling of the selectivity at infinite dilution of ionic liquids. Additionally, auxiliary models were developed to overcome the potential bias from big activity coefficient at infinite dilution from the solute. Data from SelinfDB database was used as training and internal validation sets in QSPR model development. External validation was done with the data from literature. The selection of the best models was done using decision functions that aim to diminish bias in prediction of the data points associated with the underrepresented ionic liquids or extreme temperatures. The best models were used for the virtual screening for potential azeotrope breakers of aniline + n-dodecane mixture. The subject of screening was a combinatorial library of ionic liquids, created based on the previously unused combinations of cations and anions from SelinfDB and the test set extractants. Both selectivity at infinite dilution and auxiliary models show good performance in the validation. Our models’ predictions were compared to the ones of the COSMO-RS, where applicable, displaying smaller prediction error. The best ionic liquid to extract aniline from n-dodecane was suggested.

Impact of input, preservation and dilution on organic matter enrichment in lacustrine rift basin: A case study of lacustrine shale in Dehui Depression of Songliao Basin, NE China

Lacustrine rift basins in Eastern China possess large amounts of petroleum, especially the shale gas and tight sand gas in deep formations, where “sweet spots” are closely related to organic-rich shale intervals. However, the OM enrichment of deep formation shale in lacustrine rift basins and the main controlling factors have not been well-researched in previous studies. The organic matter (OM) enrichment is mainly controlled by the OM input, preservation, and/or dilution. The shales deposited in deep formations of Songliao Basin, including the Jurassic Huoshiling (J3h), Cretaceous Shahezi (K1sh), and Yingcheng (K1yc) formations, are evaluated as fair to excellent source rocks. Taking the shales as an example, the characters and impact of input, preservation, and dilution on OM enrichment in shales are discussed by utilizing the parameters of element concentrations and biomarkers. Results show that the OM sources are mixed sources of aquatic microorganisms and higher plant materials, and the higher plant materials are dominant. The bio-productivity were moderate to high. The paleoclimate was mainly the cold and semi-humid to semi-arid. The lake salinity was fresh-to brackish-water. The redox conditions were sub-reducing to sub-oxidizing. The dilution degree in Yingcheng was the strongest, followed by the Shahezi and Huoshiling. Consequently, the OM enrichment in the J3h shale was called moderate bio-productivity and preservation model; the OM enrichment in the K1sh shale was called high bio-productivity and preservation model; the OM enrichment in the K1yc shale was named high dilution model. This study not only improves the model of OM enrichment but also provide some information for the research of “Deep time” in the Cretaceous of Songliao Basin, guiding the prediction of organic-rich shale distribution in lacustrine rift basin.

Magnetism and site occupancy in epitaxial Y-rich yttrium iron garnet films

Y-rich yttrium iron garnet (Y-YIG) thin films were grown on gadolinium gallium garnet substrates using pulsed laser deposition from a ${\mathrm{YFeO}}_{3}$ target. The films are epitaxial on the substrate, and the unit cell of (001)- and (111)-oriented Y-YIG undergoes a tetragonal or rhombohedral distortion, respectively. The Y-YIG has lower room temperature magnetization but higher low-temperature magnetization than bulk YIG, and its Curie temperature was in the range of 330--400 K, depending on the growth conditions. First-principles calculations predict that ${\mathrm{Y}}_{\mathrm{Fe}}$ antisite defects are more stable in octahedral than tetrahedral Fe sites. Temperature-dependent magnetization measurements together with a superexchange dilution model and composition determined from x-ray photoelectron spectroscopy indicate that nonmagnetic species (${\mathrm{Y}}^{3+}$ and vacancies) are predominantly accommodated in the octahedral sites, but there is a significant occupancy of tetrahedral sites.

Dynamical spin chains in 4D mathcal{N} = 2 SCFTs

This is the first in a series of papers devoted to the study of spin chains capturing the spectral problem of 4d mathcal{N} = 2 SCFTs in the planar limit. At one loop and in the quantum plane limit, we discover a quasi-Hopf symmetry algebra, defined by the R-matrix read off from the superpotential. This implies that when orbifolding the mathcal{N} = 4 symmetry algebra down to the mathcal{N} = 2 one and then marginaly deforming, the broken generators are not lost, but get upgraded to quantum generators. Importantly, we demonstrate that these chains are dynamical, in the sense that their Hamiltonian depends on a parameter which is dynamically determined along the chain. At one loop we map the holomorphic SU(3) scalar sector to a dynamical 15-vertex model, which corresponds to an RSOS model, whose adjacency graph can be read off from the gauge theory quiver/brane tiling. One scalar SU(2) sub-sector is described by an alternating nearest-neighbour Hamiltonian, while another choice of SU(2) sub-sector leads to a dynamical dilute Temperley-Lieb model. These sectors have a common vacuum state, around which the magnon dispersion relations are naturally uniformised by elliptic functions. Concretely, for the ℤ2 quiver theory we study these dynamical chains by solving the one- and two-magnon problems with the coordinate Bethe ansatz approach. We confirm our analytic results by numerical comparison with the explicit diagonalisation of the Hamiltonian for short closed chains.

Expanding Use of Deoxycholic Acid for Body Contouring: An Experimental Model for Dilution.

Expanding Use of Deoxycholic Acid for Body Contouring: An Experimental Model for Dilution.

Simulations and experiments of the generation apparatus of the DC electric field with the space charge

To make accurate measurements, field mills must be calibrated in a known DC electric field space charge in which the quantities can be control1ed. A simulation model of the generation apparatus of the electric field with a space charge has been built. Based on the combination of the electric field and the transfer of a dilute substances model, the influence of openings in the metal screen was calculated. Simulation results showed that the opening size of the high-voltage electrode has a great influence on the distribution of the electric field and ion density at the calibration zone. Next, a generation apparatus was designed and developed and ion mobility was researched. The experimental results showed that ion mobility decreased with an increase in electric field strength. However, ion mobility tends to be saturated when the electric field reaches a certain critical value. Two fitting formulas of ion mobility of positive and negative charge are proposed that can be used to predicate ion mobility in a high electric field.

Identifying groups of determinants in Bayesian model averaging using Dirichlet process clustering

AbstractModel uncertainty is a pervasive problem in regression applications. Bayesian model averaging (BMA) takes model uncertainty into account and identifies robust determinants. However, it requires the specification of suitable model priors. Mixture model priors are appealing because they explicitly account for different groups of covariates as robust determinants. Specific Dirichlet process clustering (DPC) model priors are proposed; their correspondence to the binomial model prior derived and methods to perform the BMA analysis including a DPC postprocessing procedure to identify groups of determinants are outlined. The application of these model priors is demonstrated in a simulation exercise and in an empirical analysis of cross‐country economic growth data. The BMA analysis is performed using the Markov chain Monte Carlo model composition sampler to obtain samples from the posterior of the model specifications. Results are compared with those obtained under a beta‐binomial and a collinearity‐adjusted dilution model prior.

Light hole states in a strained quantum dot: Numerical calculation and phenomenological models

Starting from the numerical solution of the 6-band \textbf{k.p} description of a lattice-mismatched ellipsoidal quantum dot situated inside a nanowire, including a spin Zeeman effect with values appropriate to a dilute magnetic semiconductor, we propose and test phenomenological models of the effect of the built-in strain on the heavy hole, light hole and exciton states. We test the validity and the limits of a description restricted to a ($\Gamma_8$) quadruplet of ground states and we demonstrate the role of the interactions of the light-hole state with light-hole excited states. We show that the built-in axial strain not only defines the character, heavy-hole or light-hole, of the ground state, but also mixes significantly the light-hole state with the split-off band's states: Even for a spin-orbit energy as large as 1 eV, that mixing induces first-order modifications of properties such as the spin value and anisotropy, the oscillator strength, and the electron-hole exchange, for which we extend the description to the light-hole exciton. CdTe/ZnTe quantum dots are mainly used as a test case but the concepts we discuss apply to many heterostructures, from mismatched II-VI and III-V quantum dots and nanowires, to III-V nanostructures submitted to an applied stress and to silicon nanodevices with even smaller residual strains.

Effects of energetic particles on the density-gradient-driven collisionless trapped electron mode instability in tokamak plasmas

We investigate analytically the effects of energetic particles (EPs) on the instability of the density-gradient-driven collisionless trapped electron mode (CTEM) through linear gyrokinetic theory and bounce kinetic theory in tokamak plasmas. The effects of EPs, including fusion-born alpha particles and neutral-beam-injection-driven beam ions, on the CTEM instability are compared for the dynamic model with slowing-down (SD) and equivalent Maxwellian (EM) equilibrium EP distribution functions and dilution model. It is found that the density-gradient-driven CTEM instability in the long wavelength regime can be further destabilized by EPs mainly due to the downshift in the real frequency of the mode by dilution effects. This is attributed to more resonant electrons around the smaller phase velocity of the drift wave and the consequent stronger excitation of CTEM instability. The growth rate is slightly higher for the dilution model as compared to that for the dynamic model since the Landau damping effects of EPs are neglected in the dilution model. Moreover, there is no significant difference in the growth rate between the cases of SD and EM equilibrium EP distribution functions, except for the case of alpha particles and with relatively higher electron temperature.

Determining nitrogen status and quantifying nitrogen fertilizer requirement using a critical nitrogen dilution curve for hybrid indica rice under mechanical pot-seedling transplanting pattern

Field experiments of nitrogen (N) treatment at five different application rates (0, 75, 150, 225, and 300 kg ha−1) were conducted under pot-seedling mechanical transplanting (PMT) in 2018 and 2019. Two high-quality and high-yielding hybrids of indica rice, Huiliangyou 898 and Y Liangyou 900, were used in this study. The N nutrition index (NNI) and accumulated N deficit (Nand), used to assess the N nutrition status in real-time, were calculated for the indica cultivars under PMT with a critical nitrogen concentration (Nc) dilution model based on shoot dry matter (DM) during the whole rice growth stage. The relationships between NNI and Nand with relative yield (RY) were determined, and accurate N application schemes were developed for hybrids indica rice under PMT. The results indicated that high application rate of N-fertilizer significantly increased the concentrations of shoot DM and N in aboveground organs during the observed stages in the two cultivars for two years (P<0.05). The Nc dilution model of hybrid indica cultivars was Nc=4.02DM−0.42 (R2=0.97) combining the two cultivars under PMT. Root-mean-square error and normalized root-mean-square error of the curve verification were 0.23 and 10.61%, respectively. The NNI and Nand ranged from 0.58 to 1.31 and 109 to –55 kg ha−1, respectively, in the two cultivars for all N treatments. NNI showed a linear relationship with Nand during the entire growth stage (0.53<R2<0.99, P<0.01). In addition, NNI showed a linear-plateau relationship with RY (0.73<R2<0.92, P<0.01) throughout the observed stages. These results suggest that the models can accurately diagnose the N-nutrition status and support effective N-fertilizer management in real-time for hybrid indica rice under PMT.

Organic-Inorganic Geochemical Characteristics of the Upper Permian Pusige Formation in a High-Saline Lake Basin, Tarim Basin: Implications for Provenance, Paleoenvironments, and Organic Matter Enrichment

The third member (M3) of the Upper Permian Pusige Formation is a prominent organic-rich lacustrine mudstone sequence within the Yecheng-Hetian Sag, Tarim Basin, hosting major petroleum resources. However, its depositional history and organic matter (OM) enrichment mechanism have received little attention. Therefore, various organic and inorganic geochemical analyses were performed on thirty-four core samples from the Well DW1, to elucidate their depositional paleoenvironments, provenance, and tectonic setting, as well as the controlling factors of OM enrichment. Results showed that the M3 mudstones are classified as poor- to fair-quality hydrocarbon source rocks with mature type II-III kerogen, considering their low organic geochemical parameters. Paleosalinity indexes (e.g., Beq, Sr/Ba, and B/Ga) indicated the typical high-saline lacustrine water body, in which redox state was the oxic-dysoxic as suggested by multiple indicators. Many paleoclimate and weathering proxies suggest a dominant semiarid condition and low weathering degree in the Yecheng-Hetian Sag, which led to that weathered felsic rocks from the West Kunlun Orogen to the southwest of basin were quickly transported into the lake basin. Detrital materials carrying nutrient elements finally promoted the development of relatively high paleoproductivity indicated by fairly high P/Ti and Ba/Al ratios. The negative relationship between P/Ti and total organic carbon (TOC) indicates that paleoproductivity was not the main controlling factor. The correlations among TOC and P/Ti and other multiple proxies suggest that the OM enrichment can be interpreted as both the “preservation model” and “dilution model.” Although the water body was relatively oxygen-riched, high sedimentation rate could largely shorten the exposure time of OM with oxygen, thus decreased the decomposition of OM. In particular, the high-saline, stratified lake water may also restrain the degradation of OM. Furthermore, detrital dilution exerted a potential effect on TOC abundances. On the basis of the above results, a developing model was established to decipher the formation mechanism of OM in these M3 mudstones.

Application of screening tools for environmental hazard and risk to support assessment and subsequent prioritization of effluent discharges from the oil and gas industry

Assessment and management of effluent discharges are key to avoid environmental deterioration. Often compliance with discharge regulations and permits is based on a limited set of chemical parameters, while information on whole-effluent hazardous properties (toxicity, bioaccumulation potential, persistence) and environmental risks is lacking. The need to collect those data and to become more effective in quickly identifying high risk activities, without extensive laboratory testing, has led to the development of screening tools to complement information on chemical composition. A simple, Tier-1 screening 'Toolbox' is proposed which is comprised of Solid Phase Micro Extraction with Gas Chromatographic analysis (SPME-GC), the in-vitro ecotoxicity assay Microtox and a simple weathering assay. When combined with dilution modelling screening level risk assessments can be performed providing additional lines of evidence to support a Weight of Evidence type of analysis. This enables prioritisation of discharges that may be deemed to require higher tier assessment. The Toolbox was trialled on a number of produced water samples collected from offshore oil and gas facilities and effluents from petroleum processing and manufacturing sites. In contrast to what has been reported for petroleum products, results showed only moderate correlation between bioavailable hydrocarbons (bHC) and toxicity, which might be related to the possible presence of toxic contaminants from other chemical classes or to methodological issues such as sub-optimal conditions during transport. The methods employed were quick, inexpensive and simple to conduct. They require relatively small volumes of sample, which is especially advantageous when evaluating discharges from remote offshore facilities. The Toolbox adds valuable information on whole effluent properties to existing data e.g. on chemical composition which can improve understanding of which discharges are more likely to pose a risk to the environment and so require further investigation or risk management. This article is protected by copyright. All rights reserved.

Boundary CFT and Tensor Network Approach to Surface Critical Phenomena of the Tricritical 3-State Potts model

One-dimensional edges of classical systems in two dimension sometimes show surprisingly rich phase transitions and critical phenomena, particularly when the bulk is at criticality. As such a model, we study the surface critical behavior of the 3-state dilute Potts model whose bulk is tuned at the tricritical point. To investigate it more precisely than in the previous works [Y. Deng and H. W. J. Bl\"ote, Phys. Rev. E 70, 035107(R) (2004); Phys. Rev. E 71, 026109 (2005)], we analyze it from the viewpoint of the boundary conformal field theory (BCFT). The complete classification of the conformal boundary conditions for the minimal BCFTs discussed in [R. E. Behrend et al., Nucl. Phys. B 579, 707 (2000)] allows us to collect the twelve boundary fixed points in the tricritical 3-state Potts BCFT. Employing the tensor network renormalization method, we numerically study the surface phase diagram of the tricritical 3-state Potts model in detail, and reveal that the eleven boundary fixed points among the twelve can be realized on the lattice by controlling the external field and coupling strength at the boundary. The last unfound fixed point would be out of the physically sound region in the parameter space, similarly to the `new' boundary condition in the 3-state Potts BCFT.

Ferromagnetic and spin-glass like transition in the q-neighbor Ising model on random graphs

The q-neighbor Ising model is investigated on homogeneous random graphs with a fraction of edges associated randomly with antiferromagnetic exchange integrals and the remaining edges with ferromagnetic ones. It is a nonequilibrium model for the opinion formation in which the agents, represented by two-state spins, change their opinions according to a Metropolis-like algorithm taking into account interactions with only a randomly chosen subset of their q neighbors. Depending on the model parameters in Monte Carlo simulations, phase diagrams are observed with first-order ferromagnetic transition, both first- and second-order ferromagnetic transitions and second-order ferromagnetic and spin-glass-like transitions as the temperature and fraction of antiferromagnetic exchange integrals are varied; in the latter case, the obtained phase diagrams qualitatively resemble those for the dilute spin-glass model. Homogeneous mean-field and pair approximations are extended to take into account the effect of the antiferromagnetic exchange interactions on the ferromagnetic phase transition in the model. For a broad range of parameters, critical temperatures for the first- or second-order ferromagnetic transition predicted by the homogeneous pair approximation show quantitative agreement with those obtained from Monte Carlo simulations; significant differences occur mainly in the vicinity of the tricritical point in which the critical lines for the second-order ferromagnetic and spin-glass-like transitions meet.Graphic abstract

SARS-CoV-2 and indoor/outdoor air samples: a methodological approach to have consistent and comparable results

Since the beginning of coronavirus disease 2019 (COVID-19) pandemic, large attention has been focused on the relationship between SARS-CoV-2 diffusion and environment. As a matter of fact, clear evidence of the transmission of SARS-CoV-2 via respiratory aerosol would be of primary importance; at the same time, checking the presence of SARS-CoV-2 in wastewater can be extremely useful to control the diffusion of the disease. Up to now, many studies report SARS-CoV-2 concentrations in indoor/outdoor air samples or water/wastewater samples that can differ by order of magnitude. Unfortunately, complete information about the scientific approach of many studies is still missing, relating to: samplers and sampling materials performances, recovery tests, measurement uncertainty, robustness, detection and quantification limits, infectivity of captured virus, virus degradation during sampling, influence of sample pre-treatments (included freezing) on results, effects of inhibitors, sample alterations due to manipulation, validation of methods and processes, quality assurance according to ISO/IEC 17025 requirements.Based on the first experiences focused on the presence of SARS-CoV-2 in environmental samples such as air quality filters or impingers collection solutions, the present study describes a coherent preliminary approach to SARS-CoV-2 indoor and outdoor air sampling in order to overcome the evident lack of standardization. Three aspects are highlighted here: the first solution to assure quality and consistency to air sampling relies on the development of recovery tests using standard materials and investigating sampling materials, sampling techniques, sampling durations, sample conservation and pre-treatments; secondly, in order to overcome the shortcomings of every single sampling technique, coupling different samplers in parallel sampling could be an efficient strategy to collect more information and make data more reliable; finally, with regards to airborne virus sampling, the results could be confirmed by simplified emission and dilution models.

The Role of New Posaconazole Formulations in the Treatment of Candida albicans Infections: Data from an In Vitro Pharmacokinetic-Pharmacodynamic Model.

Posaconazole is more active than fluconazole against Candida albicansin vitro and is approved for the treatment of oropharyngeal candidiasis but not for that of invasive candidiasis (IC). Here, we explored the efficacy of posaconazole against C. albicans in an in vitro pharmacokinetic/pharmacodynamic (PK/PD) model of IC and determined the probability of pharmacodynamic target attainment for the oral solution and intravenous (i.v.)/tablet formulations. Three clinical C. albicans isolates (posaconazole MICs, 0.008 to 0.25 mg/liter) were studied in the in vitro PK/PD dilution model simulating steady-state posaconazole PK. The in vitro exposure-effect relationship, area under the 24-h free drug concentration curve (fAUC0-24)/MIC, was described and compared with in vivo outcome in animals with IC. PK/PD susceptibility breakpoints and trough levels required for optimal treatment were determined for EUCAST and CLSI 24-h/48-h (CLSI24h/CLSI48h) methods using the fAUC0-24/MIC associated with half-maximal activity (EI50) and Monte Carlo simulation analysis for oral solution (400 mg every 12 hours [q12h]) and i.v./tablet formulations (300 mg q24h). The in vitro mean (95% confidence interval [CI]) EI50 was 330 (183 to 597) fAUC0-24/MIC for CLSI24h and 169 (92 to 310) for EUCAST/CLSI48h methods, which are close to the near-stasis in vivo effect. The probability of target attainment for EI50 was estimated; for the wild-type isolates (MIC ≤ 0.06 mg/liter), it was low for the oral solution and higher than 95% for the i.v./tablet formulations for the EUCAST/CLSI48h methods but not for the CLSI 24-h method. Non-wild-type isolates with EUCAST/CLSI48h MICs of 0.125 and 0.25 mg/liter would require trough levels of >1.2 and >2.4 mg/liter, respectively. Posaconazole i.v./tablet formulations may have a role in the therapy of invasive infections by wild-type C. albicans isolates, provided that a steady state is reached quickly. A PK/PD susceptibility breakpoint at the epidemiological cutoff (ECV/ECOFF) of 0.06 mg/liter was determined.

Metastability for the dilute Curie–Weiss model with Glauber dynamics

We analyse the metastable behaviour of the dilute Curie-Weiss model subject to a Glauber dynamics. The model is a random version of a mean-field Ising model, where the coupling coefficients are Bernoulli random variables with mean $p\in (0,1)$. This model can be also viewed as an Ising model on the Erd\H{o}s-R\'enyi random graph with edge probability $p$. The system is a Markov chain where spins flip according to a Metropolis dynamics at inverse temperature $\beta$. We compute the average time the system takes to reach the stable phase when it starts from a certain probability distribution on the metastable state (called the last-exit biased distribution), in the regime where $N\to\infty$, $\beta>\beta_c=1$ and $h$ is positive and small enough. We obtain asymptotic bounds on the probability of the event that the mean metastable hitting time is approximated by that of the Curie-Weiss model. The proof uses the potential theoretic approach to metastability and concentration of measure inequalities.