Liquid Theory Research Articles

Unique solvent effect of water in radical cyclization reaction

The radical cyclization reaction in the aqueous environment by Yorimitsu et al. is revisited using the RISM-SCF-cSED method, a hybrid of quantum chemistry and statistical mechanics theory for molecular liquids. The difference between the barrier height of the forward reaction from the intermediate E-rot, the cyclization step, and that of the backward reaction is crucial to the reaction yield. Considering the effect of hydrogen bonding through the RISM theory, we found that the barrier height for the forward reaction is lower, especially in water. In other words, considering microscopic solvation effects clearly shows the difference between water and DMSO solvents, explaining the remarkable acceleration of the reaction in the aqueous environment.

Pressure-dependent structural and electronic instabilities in LaSb$_2$

LaSb_22 exhibits a large, non-saturating, linear magnetoresistance at low temperatures, defying the expectations of Fermi liquid theory. This is thought to be caused by charge density wave order emerging below an abrupt, hysteretic anomaly in the resistivity at \sim∼ 355 K. We find that, under hydrostatic pressure, this anomaly becomes much more pronounced, develops strong hysteresis, and shifts rapidly towards lower temperatures. The anomaly is fully suppressed by only 6 kbar. Moreover, we observe a second transition anomaly at lower temperature, which likewise disappears under pressure. These findings are discussed in the context of a structural transition recently discovered in the sister material CeSb_22 and of density functional theory calculations, which indicate that the SmSb_22-type structure adopted by LaSb_22 at ambient conditions is unstable at moderate applied pressures.

Thermal disruption of a Luttinger liquid

The Tomonaga–Luttinger liquid (TLL) theory describes the low-energy excitations of strongly correlated one-dimensional (1D) fermions. In the past years, a number of studies have provided a detailed understanding of this universality class. More recently, theoretical investigations that go beyond the standard low-temperature, linear-response TLL regime have been developed. While these provide a basis for understanding the dynamics of the spin-incoherent Luttinger liquid, there are few experimental investigations in this regime. Here we report the observation of a thermally induced, spin-incoherent Luttinger liquid in a 6Li atomic Fermi gas confined to 1D. We use Bragg spectroscopy to measure the suppression of spin-charge separation and the decay of correlations as the temperature is increased. Our results probe the crossover between the coherent and incoherent regimes of the Luttinger liquid and elucidate the roles of the charge and the spin degrees of freedom in this regime.

Theory and Simulations of Ionic Liquids in Nanoconfinement.

Room-temperature ionic liquids (RTILs) have exciting properties such as nonvolatility, large electrochemical windows, and remarkable variety, drawing much interest in energy storage, gating, electrocatalysis, tunable lubrication, and other applications. Confined RTILs appear in various situations, for instance, in pores of nanostructured electrodes of supercapacitors and batteries, as such electrodes increase the contact area with RTILs and enhance the total capacitance and stored energy, between crossed cylinders in surface force balance experiments, between a tip and a sample in atomic force microscopy, and between sliding surfaces in tribology experiments, where RTILs act as lubricants. The properties and functioning of RTILs in confinement, especially nanoconfinement, result in fascinating structural and dynamic phenomena, including layering, overscreening and crowding, nanoscale capillary freezing, quantized and electrotunable friction, and superionic state. This review offers a comprehensive analysis of the fundamental physical phenomena controlling the properties of such systems and the current state-of-the-art theoretical and simulation approaches developed for their description. We discuss these approaches sequentially by increasing atomistic complexity, paying particular attention to new physical phenomena emerging in nanoscale confinement. This review covers theoretical models, most of which are based on mapping the problems on pertinent statistical mechanics models with exact analytical solutions, allowing systematic analysis and new physical insights to develop more easily. We also describe a classical density functional theory, which offers a reliable and computationally inexpensive tool to account for some microscopic details and correlations that simplified models often fail to consider. Molecular simulations play a vital role in studying confined ionic liquids, enabling deep microscopic insights otherwise unavailable to researchers. We describe the basics of various simulation approaches and discuss their challenges and applicability to specific problems, focusing on RTIL structure in cylindrical and slit confinement and how it relates to friction and capacitive and dynamic properties of confined ions.

Mesoscopic theory for ionic liquids and concentrated electrolytes in a slit with charged walls

Concentrated electrolytes and ionic liquids confined between parallel charged plates are studied within a theory combining density functional and field-theoretic methods, extended in this work to the slit geometry. We obtain charge- and density profiles, as well as the excess grand potential as a function of the slit width L in the self-consistent Gaussian approximation. For large density of ions, the obtained disjoining pressure exhibits oscillatory asymptotic decay for increasing L, with the decay length that agrees with the results of recent experiments. On a general level, we show that if the charge density decays with a distance from a charged surface in the oscillatory way, then the electrostatic energy of the slit with charged walls also decays with L in an oscillatory way with the same characteristic lengths. The oscillatory decay disagrees with the asymptotic repulsion obtained in the surface force balance experiments. We argue that in the experiment, the lack of the attraction between the confining surfaces for large L may follow from slow ordering of the isotropic fluid absorbed in the expanding slit into layers with alternating charge.

Relationship Between Asset Quality and Liquidity- Evidence From Microfinance Banks in Kenya

The dynamism of the microfinance sector has benefited microfinance banks, resulting in significant transformation in the number of users served as well as the diversity of products and services offered. However, numerous microfinance banks have ended up with a liquidity ratio that is much lower than the required limit. Consequently, MFB deposits are dwindling, loan books are reducing, and profits are declining, all of which have an impact on MFBs' intermediation role. This study therefore sought to assess the relationship between asset quality and liquidity of microfinance banks in Kenya. The Efficient Structure Theory and Preference theory of Liquidity informed the study. This study employed causal research design and adopted the positivism research philosophy. The study population included all the 13 micro finance institutions, which were operations in Kenya between 2012 and 2018. The study adopted a census approach by focusing on all the 13 MFBs in Kenya. The study found that Asset quality had a positive and significant effect on liquidity of microfinance banks in Kenya. The study recommends that the management of Microfinance bank managers should capitalize on periods of high loan demand by offering attractive lending rates to attract more loan clients to maintain a stable liquidity position. However, it is important to ensure that the lending rates are moderate to avoid accumulating microfinance losses if the loan is not repaid in accordance with the agreed-upon contract. Keywords: Asset Quality, Liquidity, Efficiency Structure Theory, Liquidity Preference Theory and Microfinance Banks DOI: 10.7176/EJBM/15-10-06 Publication date: May 31 st 2023

Evidence for an emergent anomalous metallic state in compressed titanium

The anomalous metallic state (AMS) emerging from a quantum superconductor-to-metal transition is a subject of great current interest since this exotic quantum state exhibits unconventional transport properties that challenge the core physics principles of Fermi liquid theory. As the AMS concept is historically derived from disordered two-dimensional (2D) systems, related studies have predominately concentrated on 2D materials. The AMS behaviors in three-dimensional (3D) systems have been rarely reported to date, which raises intriguing questions on the fundamental nature of pertinent physics. Here, we report experimental evidence for a 3D AMS in highly compressed titanium metal that exhibits superconductivity with a critical temperature (Tc) reaching near-record 25.1K among elemental superconductors, offering a favorable material template for exploring 3D AMS. At sufficiently strong magnetic fields, unusual transport behaviors set in over a wide pressure range, showcasing AMS hallmarks of a low-temperature saturation resistance below the Drude value and giant positive magnetoresistance. These findings reveal a 3D AMS in simple elemental systems and, more importantly, provide a fresh platform for probing the decades-long enigmatic underlying physics.

Spin-Liquid Insulators Can Be Landau's Fermi Liquids.

The long search for insulating materials that possess low-energy quasiparticles carrying electron's quantum numbers except charge-inspired by the neutral spin-1/2 excitations, the so-called spinons, exhibited by Anderson's resonating-valence-bond state-seems to have reached a turning point after the discovery of several Mott insulators displaying the same thermal and magnetic properties as metals, including quantum oscillations in a magnetic field. Here, we show that such anomalous behavior is not inconsistent with Landau's Fermi liquid theory of quasiparticles at a Luttinger surface. That is the manifold of zeros within the Brillouin zone of the single-particle Green's function at zero frequency, and which thus defines the spinon Fermi surface conjectured by Anderson.

Quantum version of the integral equation theory-based dielectric scheme for strongly coupled electron liquids.

A novel dielectric scheme is proposed for strongly coupled electron liquids, which handles quantum mechanical effects beyond the random phase approximation level and treats electronic correlations within the integral equation theory of classical liquids. The self-consistent scheme features a complicated dynamic local field correction functional and its formulation is guided by abinitio path integral Monte Carlo simulations. Remarkably, our scheme is capable of providing unprecedently accurate results for the static structure factor with the exception of the Wigner crystallization vicinity, despite the absence of adjustable or empirical parameters.

Application of the reference interaction site model self-consistent field method based on the Dirac-Hartree–Fock wave function to a chemical reaction

The reference interaction site model self-consistent field (RISM-SCF) method is a combined method of the electronic structure theory of molecules and the integral equation theory of molecular liquids. The RISM-SCF method based on the Dirac-Hartree-Fock wave function, recently proposed, is applied to a chemical reaction, specifically, a Menshutkin reaction in aqueous solution. The Helmholtz energy profile along the reaction coordinate is calculated and the characteristics of the reaction are discussed based on energy component analysis.

Morphological growth criterion for faceted to non-faceted transition in pure materials

A criterion to explain the morphological growth transition from faceted to non-faceted (f-nf) morphology in the case of directional solidification is presented for pure materials. The criterion is based on the number of atomic layers at the solid–liquid interface and allows a foreknowledge of the solidification growth velocity at which f-nf transition becomes significant. The basis for the transition criterion hinges on the Cahn theory of interface structure and the theory of liquid–solid transition by the maximum entropy production rate (MEPR) principle. The criterion is tested with a number of pure materials and compared with experimental measurements for salol. The criterion fits quite well with available experimental data.

No Theories for the Liquidity of This Desire

No Theories for the Liquidity of This Desire is a visual and poetic meditation on desire as an embodied practice of cartography. The short film responds to and reflects (on) Dionne Brand’s liquid theories of self-creation and way-finding as a Black being in diaspora. A collection of still frames accompanies the transcription of the original work, which can be accessed in full at: https://www.youtube.com/watch?v=_fdymeQxPYs&t=183s . No Theories was shot in Anguilla during February 2021.

Collective density fluctuations of strange metals with critical Fermi surfaces

Recent spectroscopic measurements in a number of strongly correlated metals that exhibit non-Fermi liquid like properties have observed evidence of anomalous frequency and momentum-dependent charge-density fluctuations. Specifically, in the strange metallic regime of the cuprate superconductors, there is a featureless particle-hole continuum exhibiting unusual power-laws, and experiments suggest that the plasmon mode decays into this continuum in a manner that is distinct from the expectations of conventional Fermi liquid theory. Inspired by these new experimental developments, we address the nature of low-energy collective modes and the particle-hole continua for different "solvable" lattice models of non-Fermi liquids that host a critical Fermi surface -- a sharp electronic Fermi surface without any low-energy electronic quasiparticles. We scrutinize theoretically the possible existence of a long-lived zero-sound mode, which is renormalized to the plasma frequency in the presence of long-ranged coulomb interactions, and its decay into the continuum over a wide range of frequencies and momenta. Quite remarkably, some of the models analyzed here can account for certain aspects of the universal experimental observations, that clearly lie beyond the purview of standard Fermi liquid theory.

Linear and nonlinear edge dynamics of trapped fractional quantum Hall droplets

We report numerical studies of the linear and nonlinear edge dynamics of a non-harmonically-confined macroscopic fractional quantum Hall fluid. In the long-wavelength and weak excitation limit, observable consequences of the fractional transverse conductivity are recovered. The first nonuniversal corrections to the chiral Luttinger liquid theory are then characterized: for a weak excitation in the linear response regime, cubic corrections to the linear wave dispersion and a broadening of the dynamical structure factor of the edge excitations are identified; for stronger excitations, sizable nonlinear effects are found in the dynamics. The numerically observed features are quantitatively captured by a nonlinear chiral Luttinger liquid quantum Hamiltonian that reduces to a driven Korteweg--de Vries equation in the semiclassical limit. Experimental observability of our predictions is finally discussed.

Relativistic liquids: GENERIC or EIT?

We study the GENERIC hydrodynamic theory for relativistic liquids formulated by Öttinger and collaborators. We use the maximum entropy principle to derive its conditions for linear stability (in an arbitrary reference frame) and for relativistic causality. In addition, we show that, in the linear regime, its field equations can be recast into a symmetric-hyperbolic form. Once rewritten in this way, the linearised field equations turn out to be a particular realisation of the Israel–Stewart theory, where some of the Israel–Stewart free parameters are constrained. This also allows us to reinterpret the GENERIC framework in view of the principles of extended irreversible thermodynamics and to discuss its physical relevance to model (possibly viscoelastic) fluids.

Modeling and Optimization of a Suspension Crystallization Separation Process for para-Xylene Purification

The morphology and DSC methods were used for measuring the crystallization kinetics of para-xylene. Solubility data from DSC experiments were fitted using the activity coefficient model and classical solid–liquid phase equilibrium theory, while the rates of nucleation, growth, aggregation, and breakage (functions of supersaturation) were built from morphological experiments. The particle size distribution was modeled via a population balance equation and validated by experimental data on a suspension crystallization separation process. The effects of the crystallizer operating temperature and residence time on product yield were also investigated; although the rates of nucleation, growth, breakage, and aggregation increase with decreasing temperature and increasing residence time, the breakage and aggregation are dominant at low temperatures and long residence times. Therefore, the crystallization process should be operated at an optimal temperature and residence time. The models built for this work can be used further in additional process design and optimization.

Generalised Isentropic Relations in Thermodynamics

Isentropic processes in thermodynamics are fundamental to our understanding of numerous physical phenomena across different scientific and engineering fields. They provide a theoretical reference case for the evaluation of real thermodynamic processes and observations. Yet, as analytical relations for isentropic transformations in gas dynamics are limited to ideal gases, the inability to analytically describe isentropic processes for non-ideal gases is a fundamental shortcoming. This work presents generalised isentropic relations in thermodynamics based on the work by Kouremenos et al., where three isentropic exponents γPv, γTv and γPT are introduced to replace the ideal gas isentropic exponent γ to incorporate the departure from the non-ideal gas behaviour. The general applicability of the generalised isentropic relations is presented by exploring its connections to existing isentropic models for ideal gases and incompressible liquids. Generalised formulations for the speed of sound, the Bernoulli equation, compressible isentropic flow transformations, and isentropic work are presented thereafter, connecting previously disjoint theories for gases and liquids. Lastly, the generalised expressions are demonstrated for practical engineering examples, and their accuracy is discussed.

Unusual fluid of one-dimensional disordered bosons at finite temperature

In previous important examinations by Aleiner et al. [Nat. Phys. 6, 900 (2010)] and Michal et al. [Proc. Natl. Acad. Sci. (U.S.A.) 113, E4455 (2016)], the fluid insulator transition has been explored in one-dimensional (1D) disordered bosons by analytical methods. However, the nature of this ``fluid'' is still not quite understood. Here we shed more light on this ``fluid'' by studying its properties under changes in the average particle number $\ensuremath{\langle}N\ensuremath{\rangle}$ and temperature $T$ in the absence of superfluidity. For this purpose, the worm algorithm path-integral Monte Carlo method is utilized in the grand-canonical ensemble. A measure for the width of path fluctuations is introduced that we call ${\ensuremath{\sigma}}_{J}$. It is found that by increasing $\ensuremath{\langle}N\ensuremath{\rangle}$, ${\ensuremath{\sigma}}_{J}$ rises as the bosons become less repulsive and gain more mobility. The compressibility $\ensuremath{\chi}(\ensuremath{\mu})$, $\ensuremath{\mu}$ being the chemical potential, reveals fluid behavior at the lower $\ensuremath{\gamma}$ and a proposed Bose-glass phase at the larger $\ensuremath{\gamma}$ (the Lieb-Liniger interaction parameter). The kinetic energy ${E}_{K}$ versus $\ensuremath{\gamma}$ at various $T$ signals a transition by its convergence towards a common value. ${E}_{K}$ versus $\ensuremath{\mu}$ reveals a peculiar inversion as one goes from small to larger values of the speckle strength $\ensuremath{\langle}V\ensuremath{\rangle}$ demonstrating a complex influence of the disorder. A tipover of ${E}_{K}$ versus $\ensuremath{\gamma}$ from an increasing to a decreasing trend at the lower $\ensuremath{\gamma}$ also signals a transition. Further, Luttinger's liquid theory cannot be applied to describe 1D bosons in strong disorder at finite $T$ because of the absence of superfluidity. Moreover, $\ensuremath{\langle}V\ensuremath{\rangle}$ largely controls the behavior of $\ensuremath{\chi}(\ensuremath{\mu})$, the pair-correlation function at the origin ${g}_{2}(0)$, and ${E}_{K}$. Surprisingly, the diffusion constant ${D}_{0}$ does not obey the classical isomorphism as it rises with $T$. We also emphasize the importance of this work via its applicability to quantum wires.

Predicting anti‑cancer drugs’ dissolution in supercritical carbon dioxide

There are many different kinds of chemotherapy or chemo drugs are used for treating cancer. All of These medicine from chemical composition, how they are prescribed and given, how useful they are in treating certain types of cancer, and the side effects they might have. Nobody can deny that all medicines to treat cancer work in the different ways. The solubility of Azathioprine, as an immunosuppressive and anti-cancer drug, in supercritical carbon dioxide (SC-CO2) was measured for the first time. Under the applied conditions in terms of pressure (120–270 bar) and temperature (308–338 K), mole fractions were obtained in the range of 0.27 × 10−5 to 1.83 × 10−5. Three types of methods including (1) two equations of states (EoSs), namely Peng-Robinson (PR) and Soave–Redlich–Kwong (SRK) with vdW2 mixing rule (2) expanded liquid theory (3) nine semi-empirical density-based models were selected to correlate the solubility data of drug. Our developed correlation presents the absolute average relative deviation (AARD) of 9.54% for predicting 316 experimental measurements. After all we show that, the most accurate correlation in the literature presents the AARD = 14.90% over the same database. Furthermore, 56.2% accuracy improvement in the solubility prediction of the anti‑cancer drugs in supercritical CO2 is the primary outcome of the current study.

Breakdown of the scaling relation of anomalous Hall effect in Kondo lattice ferromagnet USbTe

The interaction between strong correlation and Berry curvature is an open territory of in the field of quantum materials. Here we report large anomalous Hall conductivity in a Kondo lattice ferromagnet USbTe which is dominated by intrinsic Berry curvature at low temperatures. However, the Berry curvature induced anomalous Hall effect does not follow the scaling relation derived from Fermi liquid theory. The onset of the Berry curvature contribution coincides with the Kondo coherent temperature. Combined with ARPES measurement and DMFT calculations, this strongly indicates that Berry curvature is hosted by the flat bands induced by Kondo hybridization at the Fermi level. Our results demonstrate that the Kondo coherence of the flat bands has a dramatic influence on the low temperature physical properties associated with the Berry curvature, calling for new theories of scaling relations of anomalous Hall effect to account for the interaction between strong correlation and Berry curvature.