Combined Experimental-computational Approach Research Articles

Impact of thermal treatment on halloysite nanotubes: A combined experimental-computational approach

Halloysite nanotubes (HNTs) are naturally occurring aluminosilicate minerals, known for their unique tubular structure, which have garnered significant interest for a wide range of applications. This study explores the morphological changes of HNTs when subjected to thermal treatment ranging from 25 °C to 1100 °C using a combination of experimental characterization techniques and molecular dynamics simulations. Techniques such as solid-state NMR (SSNMR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area measurements, and Fourier Transform Infrared Spectroscopy (FT-IR) were employed to analyse the structural evolution. The results reveal two major transitions: the first occurring between 400 and 500 °C, corresponding to the release of intercalated water and partial distortion of the HNT structure, and the second occurring between 900 and 1000 °C, marked by the collapse of the tubular structure and the exposure of alumina on the surface. These findings provide significant insights into the thermal stability of HNTs, informing future applications, especially in high-temperature environments.

Unveiling the high-pressure behavior of thymol+carvone NADES: A combined experimental-computational approach

this study considers the high-pressure behavior of thymol + carvone Natural Deep Eutectic Solvent using a combined experimental and computational approach. Experimentally, PVT (pressure – volume/density - temperature) measurements were conducted to characterize the fluid volumetric behavior as well as compressibility and internal pressure, which are directly related with hydrogen bonding and nanoscopic structuring. Likewise, these measurements provide crucial insights into the thermodynamic properties of the considered fluid under high pressure, which is pivotal for scaling up and process design for high pressure operations. Computationally, the PC-SAFT equation of state was employed to predict phase equilibria and PVT behavior, Machine Learning for density predictions, while Density Functional Theory and Classical Molecular Dynamics simulations were considered for the structural and dynamic characterization. These simulations provides insights into the electronic structure, intermolecular interactions (hydrogen bonding), liquid structuring and they unveil the pressure's impact on microscopic interactions, structural organization, and transport properties. This comprehensive investigation aims to shed light on the behavior under high pressure, facilitating their optimization for applications in chemical processing, energy storage, and materials science.

Lead-Free Cs2AgBiCl6 Double Perovskite: Experimental and Theoretical Insights into the Self-Trapping for Optoelectronic Applications.

Lead-free double perovskites (DPs) will emerge as viable and environmentally safe substitutes for Pb-halide perovskites, demonstrating stability and nontoxicity if their optoelectronic property is greatly improved. Doping has been experimentally validated as a powerful tool for enhancing optoelectronic properties and concurrently reducing the defect state density in DP materials. Fundamental understanding of the optical properties of DPs, particularly the self-trapped exciton (STEs) dynamics, plays a critical role in a range of optoelectronic applications. Our study investigates how Fe doping influences the structural and optical properties of Cs2AgBiCl6 DPs by understanding their STEs dynamics, which is currently lacking in the literature. A combined experimental-computational approach is employed to investigate the optoelectronic properties of pure and doped Cs2AgBiCl6 (Fe-Cs2AgBiCl6) perovskites. Successful incorporation of Fe3+ ions is confirmed by X-ray diffraction and Raman spectroscopy. Moreover, the Fe-Cs2AgBiCl6 DPs exhibit strong absorption from below 400 nm up to 700 nm, indicating sub-band gap state transitions originating from surface defects. Photoluminescence (PL) analysis demonstrates a significant enhancement in the PL intensity, attributed to an increased radiative recombination rate and higher STE density. The radiative kinetics and average lifetime are investigated by the time-resolved PL (TRPL) method; in addition, temperature-dependent PL measurements provide valuable insights into activation energy and exciton-phonon coupling strength. Our findings will not only deepen our understanding of charge carrier dynamics associated with STEs but also pave the way for the design of some promising perovskite materials for use in optoelectronics and photocatalysis.

Investigation of cardiopulmonary bypass parameters on embolus transport in a patient-specific aorta.

Neurological complexities resulting from surgery requiring cardiopulmonary bypass (CPB) remain a major concern, encompassing a spectrum of complications including thromboembolic stroke and various cognitive impairments. Surgical manipulation during CPB is considered the primary cause of these neurological complications. This study addresses the overall lack of knowledge concerning CPB hemodynamics within the aorta, employing a combined experimental-computational modeling approach, featuring computational fluid dynamics simulations validated with an in vitro CPB flow loop under steady conditions. Parametric studies were systematically performed, varying parameters associated with CPB techniques (pump flow rate and hemodiluted blood viscosity) and properties related to formed emboli (size and density). This represents the first comprehensive investigation into the individual and combined effects of these factors. Our findings reveal critical insights into the operating conditions of CPB, indicating a positive correlation between pump flow rate and emboli transport into the aortic branches, potentially increasing the risk of stroke. It was also found that larger emboli were more often transported into the aortic branches at higher pump flow rates, while smaller emboli preferred lower flow rates. Further, as blood is commonly diluted during CPB to decrease its viscosity, more emboli were found to enter the aortic branches with greater hemodilution. The combined effects of these parameters are captured using the non-dimensional Stokes number, which was found to positively correlate with emboli transport into the aortic branches. These findings contribute to our understanding of embolic stroke risk factors during CPB and shed light on the complex interplay between CPB parameters.

Non-enzymatic glycation increases the failure risk of annulus fibrosus by predisposing the extrafibrillar matrix to greater stresses.

Growing clinical evidence suggests a correlation between diabetes and more frequent and severe intervertebral disc failure, partially attributed to accelerated advanced glycation end-products (AGE) accumulation in the annulus fibrosus (AF) through non-enzymatic glycation. However, in vitro glycation (i.e., crosslinking) reportedly improved AF uniaxial tensile mechanical properties, contradicting clinical observations. Thus, this study used a combined experimental-computational approach to evaluate the effect of AGEs on anisotropic AF tensile mechanics, applying the finite element models (FEM) to complement experimental testing and examine difficult-to-measure subtissue-level mechanics. Methylglyoxal-based treatments were applied to induce three physiologically relevant AGE levels in vitro. Models incorporated crosslinks by adapting our previously validated structure-based FEM framework. Experimental results showed that a threefold increase in AGE content resulted in a ∼55% increase in AF circumferential-radial tensile modulus and failure stress and a 40% increase in radial failure stress. Failure strain was unaffected by non-enzymatic glycation. Adapted FEMs accurately predicted experimental AF mechanics with glycation. Model predictions showed that glycation increased stresses in the extrafibrillar matrix under physiologic deformations, which may increase tissue mechanical failure or trigger catabolic remodeling, providing insight into the relationship between AGE accumulation and increased tissue failure. Our findings also added to the existing literature regarding crosslinking structures, indicating that AGEs had a greater effect along the fiber direction, while interlamellar radial crosslinks were improbable in the AF. In summary, the combined approach presented a powerful tool for examining multiscale structure-function relationships with disease progression in fiber-reinforced soft tissues, which is essential for developing effective therapeutic measures. STATEMENT OF SIGNIFICANCE: : Increasing clinical evidence correlates diabetes with premature intervertebral disc failure, likely due to advanced glycation end-products (AGE) accumulation in the annulus fibrosus (AF). However, in vitro glycation reportedly increases AF tensile stiffness and toughness, contradicting clinical observations. Using a combined experimental-computational approach, our work shows that increases in AF bulk tensile mechanical properties with glycation are achieved at the risk of exposing the extrafibrillar matrix to increased stresses under physiologic deformations, which may increase tissue mechanical failure or trigger catabolic remodeling. Computational results indicate that crosslinks along the fiber direction account for 90% of the increased tissue stiffness with glycation, adding to the existing literature. These findings provide insight into the multiscale structure-function relationship between AGE accumulation and tissue failure.

Pushing Technique Boundaries to Probe Conformational Polymorphism.

We present an extensive exploration of the solid-form landscape of chlorpropamide (CPA) using a combined experimental-computational approach at the frontiers of both fields. We have obtained new conformational polymorphs of CPA, placing them into context with known forms using flexible-molecule crystal structure prediction. We highlight the formation of a new polymorph (ζ-CPA) via spray-drying experiments despite its notable metastability (14 kJ/mol) relative to the thermodynamic α-form, and we identify and resolve the ball-milled η-form isolated in 2019. Additionally, we employ impurity- and gel-assisted crystallization to control polymorphism and the formation of novel multicomponent forms. We, thus, demonstrate the power of this collaborative screening approach to observe, rationalize, and control the formation of new metastable forms.

(Invited) Investigating Polymorphism in Na2Fe2F7 and Its Effect on Electrochemical Properties

With the present materials supply crunch caused by the burgeoning Li-ion battery-based electric vehicle market, more sustainable battery chemistries are needed. When considering possible chemistries, sodium (Na) and iron (Fe) stand out as promising candidates for the intercalant ions and redox centers, respectively. Recently, weberite-type sodium metal fluorides (Na2 M 2+ Mʹ 3+F7) have emerged as potential high performance Na cathode materials1-4 with predicted energy densities in the 600 to 800 Wh/kg range (higher than any known Na cathode material) and high ionic conductivity and structural stability. One of the few weberites that has been electrochemically tested so far is Na2Fe2F7 and while one study has shown it to have great, high-rate performance,2 there have been inconsistent reports regarding the structure and electrochemical properties of Na2Fe2F7.In this study, we endeavor to reconcile these characteristics using a combined experimental-computational approach. Density functional theory calculations reveal the inherent metastability of the weberite phase and the close energetics of several Na2Fe2F7 polymorphic forms, as well as the predicted (de)intercalation behavior for each Na2Fe2F7 polymorph. Experimentally, we find that Na2Fe2F7 samples inevitably contain a mixture of weberite polymorphs as characterized using a broad suite of long-range and local probes sensitive to both amorphous and crystalline phases. Notably, we present the first ever 23Na nuclear magnetic resonance (NMR) investigation into weberites and showcase NMR’s ability to parse out different local environments despite the presence of polymorphism. Electrochemically, our Na2Fe2F7 material shows respectable early capacities yet exhibits steady capacity fade, which ex situ synchrotron X-ray diffraction and 23Na NMR reveal to be associated with transformation of the weberite phase upon cycling. However, fine tuning of electrode composition and design appears to be effective at reducing this effect.Overall, this study presents an in-depth characterization of Na2Fe2F7 and provides key insights that pave the way to unlocking weberites as high energy density Na-ion cathode materials.This work made use of the shared facilities of the UC Santa Barbara MRSEC (DMR 1720256) and Center for Scientific Computing (CNS 1725797, DMR 1720256). E. E. Foley and V. C. Wu were supported by the NSF Graduate Research Fellowship Program under Grant No. DGE 1650114. This work is supported by an NSF CAREER award under Grant No. DMR 2141754. Euchner, O. Clemens, and M.A. Reddy, Npt Comput. Mater. 5 31 (2019).Park, Y. Lee, M.-K. Cho, J. Kang, W. Ko, Y.H. Jung, T.-Y. Jeon, J. Hong, H. Kim, S.-T. Myung, and J. Kim, Energy Environ. Sci. 14 1469-1479 (2021).K. Dey, N. Barman, S. Ghosh, S. Sarkar, S.C. Peter, P. Senguttuvan, Chem. Mater. 31 295-299 (2019).Kang, J. Ahn, H. Park, W. Ko, Y. Lee, S. Lee, S. Lee, S.-K. Jung, J. Kim, J. Kang, J. Ahn, H. Park, W. Ko, Y. Lee, S. Lee, J. Kim and S.-K. Jung, Adv. Funct. Mater. 32 2201816 (2022). Fig. 1 , Charge- discharge curve for Na2Fe2F7 and the weberite structure. Figure 1

Dynamically Visualized Mechano-Responsive Supramolecular Self-Assembly System for Small Molecule Release.

The mechano-responsiverelease of small molecules has received extensive attention in ultrasound (US)-controlled drug release in recent years because it can achieve non-invasive, spatiotemporally controlled precise drug release. However, the vast majority of small molecules mechano-release reported so far are based on polymer systems, which suffer from complex preparations and single mechano-response. Here, an isoguanosine (isoG) visualized mechano-responsive supramolecular self-assembly (isoG-VMRSS) system was successfully constructed by a one-pot reaction. It is completely composed of small molecules, which allows for multiple mechano-responsive releases of isoG (at least 9 times) and ultimately has potential for application in US drug release. A combined experimental-computational approach reveals the supramolecular network structure (formed by the joint action of related metal coordination bonds, boronate ester bonds and hydrogen bonds mediated by isoG) gradually formed inside the system is the underlying internal mechanism. Therefore, it provides a new and effective idea of small molecule release in the field of mechanochemistry.

A combined experimental-computational approach uncovers a role for the Golgi matrix protein Giantin in breast cancer progression.

Our understanding of how speed and persistence of cell migration affects the growth rate and size of tumors remains incomplete. To address this, we developed a mathematical model wherein cells migrate in two-dimensional space, divide, die or intravasate into the vasculature. Exploring a wide range of speed and persistence combinations, we find that tumor growth positively correlates with increasing speed and higher persistence. As a biologically relevant example, we focused on Golgi fragmentation, a phenomenon often linked to alterations of cell migration. Golgi fragmentation was induced by depletion of Giantin, a Golgi matrix protein, the downregulation of which correlates with poor patient survival. Applying the experimentally obtained migration and invasion traits of Giantin depleted breast cancer cells to our mathematical model, we predict that loss of Giantin increases the number of intravasating cells. This prediction was validated, by showing that circulating tumor cells express significantly less Giantin than primary tumor cells. Altogether, our computational model identifies cell migration traits that regulate tumor progression and uncovers a role of Giantin in breast cancer progression.

Orientation-dependent indentation reveals the crosslink-mediated deformation mechanisms of collagen fibrils.

The spatial arrangement and interactions of the extracellular matrix (ECM) components control the mechanical behavior of tissue at multiple length scales. Changes in microscale deformation mechanisms affect tissue function and are often hallmarks of remodeling and disease. Despite their importance, the deformation mechanisms that modulate the mechanical behavior of collagenous tissue, particularly in indentation and compression modes of deformation, remain poorly understood. Here, we develop an integrated computational and experimental approach to investigate the deformation mechanisms of collagenous tissue at the microscale. While the complex deformation arising from indentation with a spherical probe is often considered a pitfall rather than an opportunity, we leverage this orientation-dependent deformation to examine the shear-regulated interactions of collagen fibrils and the role of crosslinks in modulating these interactions. We specifically examine tendon and cervix, two tissues rich in collagen with quite different microstructures and mechanical functions. We find that interacting, crosslinked collagen fibrils resist microscale longitudinal compressive forces, while widely used constitutive models fail to capture this behavior. The reorientation of collagen fibrils tunes the compressive stiffness of complex tissues like cervix. This study offers new insights into the mechanical behavior of collagen fibrils during indentation, and more generally, under longitudinal compressive forces, and illustrates the mechanisms that contribute to the experimentally observed orientation-dependent mechanical behavior. STATEMENT OF SIGNIFICANCE: Remodeling and disease can affect the deformation and interaction of tissue constituents, and thus mechanical function of tissue. Yet, the microscale deformation mechanisms are not well characterized in many tissues. Here, we develop a combined experimental-computational approach to infer the microscale deformation mechanisms of collagenous tissues with very different functions: tendon and cervix. Results show that collagen fibrils resist microscale forces along their length, though widely-used constitutive models do not account for this mechanism. This deformation process partially modulates the compressive stiffness of complex tissues such as cervix. Computational modeling shows that crosslink-mediated shear deformations are central to this unexpected behavior. This study offers new insights into the deformation mechanisms of collagenous tissue and the function of collagen crosslinkers.

A combined experimental-computational approach to study interactions of topical ophthalmologic drugs with a tear film model.

Many topical ophthalmologic drug formulations are based on micellar drug delivery. Recently, a state-of-the-art delivery approach was suggested utilizing complex oil-in-water nanoemulsions loaded with active drug molecules. We study drug nanocarriers consisting of nanodroplets of nonpolar lipids with varying chain lengths coated with cationic surfactants. We employ both experimental and computational approaches. In experiments, we use a unique in vitro system that models human tear film. It mimics eye-blinking with tear inflow and evaporation. The device also allows control of the blinking rate and uses fluorescein staining to visualize the tear film model upon administration of topical ophthalmologic drugs. In the computational approach,

A combined experimental-computational approach for electrocatalytic detection of epinephrine using nanocomposite sensor based on polyaniline/nickel oxide

• A novel electrochemical sensor based on GCE/PANI/NiO nanocomposite developed for epinephrine. • Very good performances achieved at a molecular level (detection limit: micromolar; recoveries > 100% and reasonable RSDs) • The nanocomposite is cost effective, sensitive and reproducible. • Excellent practical applicability in real sample (adrenaline injection) analysis. • Computational simulations validated experimental results at an atomistic level. This study reports on a sensor based on nickel oxide nanoparticles (NiO) derived from callistemon viminalis leaf extract and the polymerization of polyaniline (PANI) supported on a glassy carbon electrode (GCE). The novel 2D sensing materials for epinephrine (EP) have been experimentally investigated and theoretically modelled. The electrochemical sensor based on GCE/PANI/NiO exhibits good sensitivity and selectivity for EP. Under optimized conditions, the oxidation peak currents of EP showed a linear dynamic range of 47–354 μM with limit of detection of 0.05 µM using square wave voltammetry. The designed sensor demonstrated good practicability for the detection of EP in adrenaline injection with good recoveries (102.0 to 105.3%) and precision (RSD of 0.22–2.15%). The Monte Carlo and molecular dynamics simulations were used to assess the active sites of the adsorbate–substrate interface and the computed binding affinities of GCE/PANI/NiO toward EP. The density functional theory calculations confirm the chemical reactivity and stability of EP with HOMO-LUMO energy band gap of −5.48 eV. This opens an insightful and new path to expand the fabrication of novel sensors based on 2D materials using a combined experimental-computational approach.

Programmable Transient Supramolecular Chiral G-quadruplex Hydrogels by a Chemically Fueled Non-equilibrium Self-Assembly Strategy.

The temporal and spatial control of natural systems has aroused great interest for the creation of synthetic mimics. By using boronic ester based dynamic covalent chemistry and coupling it with an internal pH feedback system, we have developed a new chemically fueled reaction network for non-equilibrium supramolecular chiral G-quadruplex hydrogels with programmable lifetimes from minutes, to hours, to days, as well as high transparency and conductivity, excellent injectability, and rapid self-healing properties. The system can be controlled by the kinetically controlled in situ formation and dissociation of dynamic boronic ester bonds between the cis-diol of guanosine (G) and 5-fluorobenzoxaborole (B) in the presence of chemical fuels (KOH and 1,3-propanesultone), thereby leading to a precipitate-solution-gel-precipitate cycle under non-equilibrium conditions. A combined experimental-computational approach showed the underlying mechanism of the non-equilibrium self-assembly involves aggregation and disaggregation of right-handed helical G-quadruplex superstructures. The proposed dynamic boronic ester-based non-equilibrium self-assembly strategy offers a new option to design next-generation adaptive and interactive smart materials.

Hydraulic permeability and compressive properties of porcine and human synovium

The synovium is a multilayer connective tissue separating the intra-articular spaces of the diarthrodial joint from the extra-synovial vascular and lymphatic supply. Synovium regulates drug transport into and out of the joint, yet its material properties remain poorly characterized. Here, we measured the compressive properties (aggregate modulus, Young's modulus, and Poisson's ratio) and hydraulic permeability of synovium with a combined experimental-computational approach. A compressive aggregate modulus and Young's modulus for the solid phase of synovium were quantified from linear regression of the equilibrium confined and unconfined compressive stress upon strain, respectively (HA = 4.3 ± 2.0 kPa, Es = 2.1 ± 0.75, porcine; HA = 3.1 ± 2.0 kPa, Es = 2.8 ± 1.7, human). Poisson's ratio was estimated to be 0.39 and 0.40 for porcine and human tissue, respectively, from moduli values in a Monte Carlo simulation. To calculate hydraulic permeability, a biphasic finite element model's predictions were numerically matched to experimental data for the time-varying ramp and hold phase of a single increment of applied strain (k = 7.4 ± 4.1 × 10−15 m4/N.s, porcine; k = 7.4 ± 4.3 × 10−15 m4/N.s, human). We can use these newly measured properties to predict fluid flow gradients across the tissue in response to previously reported intra-articular pressures. These values for material constants are to our knowledge the first available measurements in synovium that are necessary to better understand drug transport in both healthy and pathological joints.

A Computational Framework Examining the Mechanical Behaviour of Bare and Polymer-Covered Self-Expanding Laser-Cut Stents.

Polymer covered stents have demonstrated promising clinical outcomes with improved patency rates compared to traditional bare-metal stents. However, little is known on the mechanical implication of stent covering. This study aims to provide insight into the role of a polymeric cover on the biomechanical performance of self-expanding laser-cut stents through a combined experimental-computational approach. Experimental bench top tests were conducted on bare and covered versions of a commercial stent to evaluate the radial, axial and bending response. In parallel, a computational framework with a novel covering strategy was developed that accurately predicts stent mechanical performance. Different stent geometries and polymer materials were also considered to further improve understanding on covered stent mechanics. Results show that stent covering causes increased initial axial stiffness and up to 60% greater radial resistive force at small crimp diameters as the cover folds and self-contacts. The incorporation of a cover allows stent designs without interconnecting struts, thereby providing improved flexibility without compromising radial force. It was also shown that use of a stiffer PET polymeric covering material caused significant alterations to the radial and axial response, with the initial axial stiffness increasing six-fold and the maximum radial resistive force increasing four-fold compared to a PTFE-PU covered stent. This study demonstrates that stent covering has a substantial effect on the overall stent mechanical performance and highlights the importance of considering the mechanical properties of the combined cover and stent.

Combined Experimental and Computational Study of Ruthenium N-Hydroxyphthalimidoyl Carbenes in Alkene Cyclopropanation Reactions.

A combined experimental–computational approach has been used to study the cyclopropanation reaction of N-hydroxyphthalimide diazoacetate (NHPI-DA) with various olefins, catalyzed by a ruthenium-phenyloxazoline (Ru-Pheox) complex. Kinetic studies show that the better selectivity of the employed redox-active NHPI diazoacetate is a result of a much slower dimerization reaction compared to aliphatic diazoacetates. Density functional theory calculations reveal that several reactions can take place with similar energy barriers, namely, dimerization of the NHPI diazoacetate, cyclopropanation (inner-sphere and outer-sphere), and a previously unrecognized migratory insertion of the carbene into the phenyloxazoline ligand. The calculations show that the migratory insertion reaction yields an unconsidered ruthenium complex that is catalytically competent for both the dimerization and cyclopropanation, and its relevance is assessed experimentally. The stereoselectivity of the reaction is argued to stem from an intricate balance between the various mechanistic scenarios.

Role of anisotropy in the ballistic response of rolled magnesium

Rolled magnesium alloys exhibit pronounced tension-compression asymmetry as well as anisotropy in yield and strain-hardening behavior. Although differences in the mechanical response are reasonably well-understood, it is not clear to what extent anisotropy alters the deformation and failure of plates subjected to ballistic loading conditions. In this work, the role of texture and anisotropy in the ballistic response is investigated using a combined experimental–computational approach. Sphere impact experiments are performed on rolled magnesium plates cut from orientations that exhibit differing mechanical responses. The complex failure process is characterized by in situ diagnostics, including ultra-high-speed Digital Image Correlation and Photonic Doppler Velocimetry, and compared with simulations performed on polycrystalline aggregates using a polycrystal plasticity model for hcp metals. The anisotropic deformation behavior arises from deformation mechanisms with disparate strength and strain hardening behavior, which is well captured in the model. The occurrence of low-strength extension twinning is shown to govern the initial anisotropic deformation and bulging of the plate. When compared with post-mortem 3D X-ray microscopy, regions that experience intense basal slip are shown to be sites for damage initiation that leads to eventual fracture. The combination of experiments and simulations suggest that at low to intermediate ballistic loading rates, material orientation plays a crucial role in dictating eventual fracture and failure in strongly anisotropic metals such as in rolled magnesium alloys.

Fundamental Investigations of Factors Affecting Electrical and Transport Properties of Lewis Acidic Chloroaluminate Ionic Liquids for Application in Aluminum Ion Battery

High-performance electrochemical energy storage systems are considered key technologies to sustainable energy economy transition. Despite being one of the most mature and leading-edge battery systems, the future of lithium-ion batteries is shadowed by issues related to resource availability, high production cost, and short lifetime. For these reasons, there has been a great impetus towards the development of alternative battery technologies based on abundant and low-cost materials. Among all, aluminum-ion batteries (AIBs) are particularly promising due to high theoretical capacity, low-cost, and ease of handling and storing of metallic aluminum in ambient conditions.The majority of advanced AIB systems utilizes Lewis acidic chloroaluminate ionic liquid (IL) electrolytes, formed by combining molar excess amount of aluminum chloride (AlCl3) with an organic chloride (RCl; R: organic group). In these systems, the chloroaluminate IL electrolyte behaves as (i) a medium for ion transportation and (ii) an electroactive liquid anode material (also known as anolyte) in AIBs. Among various parameters, the AlCl3/RCl molar ratio (r) and the RCl utilized, are considered the most deterministic factors that affect the performance of AIBs. Several battery and electrolyte performance metrics including achievable specific/volumetric cell-level capacity, electrochemical stability window (ESW), ion transport properties, and conductivity, are known to be dependent on r and the RCl utilized. Despite the importance of chloroaluminate ILs in AIB research field, there is a significant lack of fundamental understandings of the effects of r and RCl on these performance matrices. The elucidation of these effects can provide fundamental insights into approaches for optimizing battery operating conditions as well as revealing important characteristics of high-performance chloroaluminate ILs.This work is focused on investigating the effects of r on the electrical and transport properties of four AlCl3-RCl ILs, where RCl includes EMIMCl (1-ethyl-3-methylimidazolium chloride), BMIMCl (1-buthyl-3-methylimidazolium chloride), TMAHCl (trimethylamine hydrochloride), and TEAHCl (triethylamine hydrochloride). A combined experimental-computational approach is utilized to obtain fundamental insights into the influence of AlCl3/RCl molar ratio on various properties of chloroaluminate ILs including ESW, ion transference number, and ionic conductivity.Our results show that the ESW of Lewis acidic chloroaluminate ILs is strongly dependent on r, as r preliminarily governs the concentration of electroactive anionic species (AlCl4 − and Al2Cl7 −) involved in electrochemical redox reactions. For Lewis acidic chloroaluminate ILs, the reduction of Al2Cl7 − to Al (4Al2Cl7 − + 3e− = Al + 7AlCl4 −) sets the cathodic limit while the oxidation of AlCl4 − to evolve Cl2 (2AlCl4 − = Al2Cl7 − + 1/2Cl2 + e−) defines the anodic limit. The cathodic limiting potential shifts positively while the anodic limiting potential shifts negatively, leading to a narrower ESW width with increasing r. Moreover, electrostatic and van der Waals forces significantly affect the cathodic and anodic limiting potentials as these interactions affect the activity of electroactive species involved. The viscosity of chloroaluminate ILs is particularly useful as it reflects the overall degree of interactions in chloroaluminate ILs. Chloroaluminate IL systems that have higher viscosities exhibit a positive shift of anodic and cathodic limiting potentials. The organic cation R+ is determined to contribute substantially to the total ionic conduction in Lewis acidic chloroaluminate ILs. To fundamentally enhance the electrochemical performance of AIBs employing chloroaluminate ILs, strategies focused on the localization of organic cations should be emphasized as they can effectively improve the proportion of ionic conduction by electroactive chloroaluminate anions while hindering the formation of cation-anion aggregates.

A combined experimental and computational approach to evaluate microclimate control at the support surface interface

Temperature and humidity conditions at the interface between a support surface and the skin, termed microclimate, has been implicated in the development of pressure ulcers. Support surface technologies have been developed to control microclimate conditions, although only a few standard test methods exist to evaluate their performance. This study describes a combined experimental-computational approach to analyzing microclimate control systems.The study used a modified physical model protocol to evaluate two specific support surface systems involving a spacer fabric cover with i) no air flow and ii) an active fan. The physical model deposited moisture at a controlled rate for 25 min, and the microclimate conditions under the model and the surrounding area were monitored for 24 h. Using the experimental data as boundary conditions, a finite element model was developed using mass transport principles, which was calibrated using experimental results. Model inputs included mass density and mass diffusivity, resulting in an estimated absolute humidity change over time.The physical model tests revealed distinct differences between the support surfaces with and without active airflow, with the former having little effect on local humidity levels (RH>75% for 24hr). By contrast, there was a spatial and temporal change in microclimate with the active fan, with sensors positioned towards the source of airflow reaching ambient conditions within 24hr. The computational model was refined to produce comparable results with respect to both the spatial distribution of microclimate and the change in values over time.The combined experimental and computation approach was able to distinguish distinct difference in microclimate change between two support surface designs. The approach could enable the efficient evaluation of different mattress design principles to aid decision making for personalized support surface solutions, for the prevention of pressure ulcers.

Orientation and stress state dependent plasticity and damage initiation behavior of stainless steel 304L manufactured by laser powder bed fusion additive manufacturing

The plasticity and ductile fracture behavior of stainless steel 304L fabricated by laser powder bed fusion additive manufacturing was investigated under both uniaxial and multiaxial loading conditions through the use of specialized geometry mechanical test specimens. Material anisotropy was probed through the extraction of samples in two orthogonal material directions. The experimentally measured plasticity behavior was found to be anisotropic and stress state dependent. An anisotropic Hill48 plasticity model, calibrated using experimental data, was able to accurately capture this behavior. A combined experimental–computational approach was used to quantify the ductile fracture behavior, considering both damage initiation and final fracture. An anisotropic Hosford–Coulomb model was used to capture the anisotropic and stress state dependent fracture behavior.