Electric field-based air nanobubbles (EF-ANBs) irrigation on efficient crop cultivation with reduced fertilizer dependency.

The advent of air nanobubbles (ANBs) has opened up a wide range of commercial applications spanning industries including wastewater treatment, food processing, biomedical engineering, and agriculture. The implementation of electric field-based air nanobubbles (EF-ANBs) irrigation presents a promising approach to enhance agricultural crop efficiency, concurrently promoting environmentally sustainable practices through reducing fertilizer usage. This study investigated the impact of EF-ANBs on the germination and overall growth of agricultural crops in soil. Results indicate a substantial enhancement in both germination rates and plant growth upon the application of EF-ANBs. Notably, the introduction of ANBs led to a significant enhancement in the germination rate of lettuce and basil, increasing from approximately 20% to 96% and from 16% to 53%, respectively over two days. Moreover, the presence of EF-ANBs facilitates superior hypocotyl elongation, exhibiting a 2.8- and a 1.6-fold increase in the elongation of lettuce and basil, respectively, over a six-day observation period. The enriched oxygen levels within the air nanobubbles expedite aerobic respiration, amplifying electron leakage from the electron transport chain (ETC) and resulting in heightened reactive oxygen species (ROS) production, playing a pivotal role in stimulating growth signaling. Furthermore, the application of EF-ANBs in irrigation surpasses the impact of traditional fertilizers, demonstrating a robust catalytic effect on the shoot, stem, and root length, as well as the leaf count of lettuce plants. Considering these parameters, a single fertilizer treatment (at various concentrations) during EF-ANBs administration, demonstrates superior plant growth compared to regular water combined with fertilizer. The findings underscore the synergistic interaction between aerobic respiration and the generation of ROS in promoting plant growth, particularly in the context of reduced fertilizer levels facilitated by the presence of EF-ANBs. This promising correlation holds significant potential in establishing more sustainability for ever-increasing environmentally conscious agriculture.

Effect of static electric fields on liquid water, its structure, dynamics, and hydrogen bond asymmetry: A molecular dynamics simulation study of TIP4P/2005 water model.

We study the effect of static electric fields of 0.1, 0.4, and 1.0 V/nm on the hydrogen bond structure and dynamics of TIP4P/2005 water at 1 bar and at temperatures between 300 and 200 K using molecular dynamics simulations. At all these temperatures, simulating liquid water with electric fields of 0.1 and 0.4 V/nm has no additional effect on its structural and dynamical changes, which otherwise already take place due to cooling. However, the introduction of 1.0 V/nm field enhances the slowing down of liquid water dynamics, crystallizes it to cubic ice at 240 and 220 K, and amorphizes it at 200 K. At 240 and 220 K, crystallization occurs within 5 and 50 ns, respectively. An electric field of 1 V/nm increases the relaxation times in addition to what cooling does. We note that when liquid water's metastability limit is reached, crystallization is averted and amorphization takes place. Both equilibrium (liquid-solid) and non-equilibrium (liquid-amorphous) transformations are observed at 1 V/nm. Moreover, with an increase in the electric field, H-bonds become stronger. However, the donor-acceptor asymmetry (the difference between the strengths of two donor/acceptor bonds) remains even when crystallization or amorphization takes place. At low temperatures, increasing electric fields on liquid water increases both its crystallization and amorphization tendencies.

Improving Structural Stability and Anticoagulant Activity of a Thrombin Binding Aptamer by Aromatic Modifications.

The thrombin binding aptamer (TBA) is a 15-mer DNA oligonucleotide (5'-GGT TGG TGT GGT TGG-3'), that can form a stable intramolecular antiparallel chair-like G-quadruplex structure. This aptamer shows anticoagulant properties by interacting with one of the two anion binding sites of thrombin, namely the fibrinogen-recognition exosite. Here, we demonstrate that terminal modification of TBA with aromatic fragments such as coumarin, pyrene and perylene diimide (PDI), improves the G-quadruplex stability. The large aromatic surface of these dyes can π-π stack to the G-quadruplex or to each other, thereby stabilizing the aptamer. With respect to the original TBA, monoPDI-functionalized TBA exhibited the most remarkable improvement in melting temperature (ΔTm ≈+18 °C) and displayed enhanced anticoagulant activity.

Vibrational Analysis of Hydration-Layer Water around Ubiquitin, Unpeeled Layer by Layer: Molecular-Dynamics Perceptions.

Classical molecular-dynamics simulations have been performed to examine the interplay between ubiquitin and its hydration-water sub-layers, chiefly from a vibrational-mode and IR viewpoint-where we analyse individual sub-layers characteristics. The vibrational Density of States (VDOS) revealed that the first solvation sub-shell indicates a confined character therein. For layers of increasing distance from the surface, the adoption of greater bulk-like spectral behaviour was evident, suggesting that vibrational harmonisation to bulk occurs within 6-7 Å of the surface.

Unraveling Adhesion Strength between Gas Hydrate and Solid Surfaces.

Natural gas hydrate is a promising future energy source, but it also poses a huge threat to oil and gas production due to its ability to deposit within and block pipelines. Understanding the atomistic mechanisms of adhesion between the hydrate and solid surfaces and elucidating its underlying key determining factors can shed light on the fundamentals of novel antihydrate materials design. In this study, large-scale molecular simulations are employed to investigate the hydrate adhesion on solid surfaces, especially with focuses on the atomistic structures of intermediate layer and their influences on the adhesion. The results show that the structure of the intermediate layer formed between hydrate and solid surface is a competitive equilibrium of induced growth from both sides, and is regulated by the content of guest molecules. By comparing the fracture behaviors of the hydrate-solid surface system with different intermediate structures, it is found that both the lattice areal density of water structure and the adsorption of guest molecules on the interface together determine the adhesion strength. Based on the analysis of the adhesion strength distribution, we have also revealed the origins of the drastic difference in adhesion among different water structures such as ice and hydrate. Our simulation indicates that ice-adhesion strength is approximately five times that of lowest hydrate adhesion strength. This finding is surprisingly consistent with the available experimental results.

Dielectric properties of ice VII under the influence of time-alternating external electric fields.

The high-pressure solid phase of water known as ice VII has recently attracted a lot of attention when its presence was detected in large exoplanets, their icy satellites, and even in Earth's mantle. Moreover, a transition of ice VII to the superionic phase can be triggered by external electric fields. Here, we investigate the dielectric responses of ice VII to applied oscillating electric fields of various frequencies employing non-equilibrium ab initio molecular dynamics. We focus on the dynamical properties of a dipole-ordered ice VII structure, for which we explored external-field-induced electronic polarisation and the vibrational spectral density of states (VDOS). These analyses are important for the understanding of collective motions in the ice-VII lattice and the electronic properties of this exotic water phase.

Gas hydrates in sustainable chemistry.

Gas hydrates have received considerable attention due to their important role in flow assurance for the oil and gas industry, their extensive natural occurrence on Earth and extraterrestrial planets, and their significant applications in sustainable technologies including but not limited to gas and energy storage, gas separation, and water desalination. Given not only their inherent structural flexibility depending on the type of guest gas molecules and formation conditions, but also the synthetic effects of a wide range of chemical additives on their properties, these variabilities could be exploited to optimise the role of gas hydrates. This includes increasing their industrial applications, understanding and utilising their role in Nature, identifying potential methods for safely extracting natural gases stored in naturally occurring hydrates within the Earth, and for developing green technologies. This review summarizes the different properties of gas hydrates as well as their formation and dissociation kinetics and then reviews the fast-growing literature reporting their role and applications in the aforementioned fields, mainly concentrating on advances during the last decade. Challenges, limitations, and future perspectives of each field are briefly discussed. The overall objective of this review is to provide readers with an extensive overview of gas hydrates that we hope will stimulate further work on this riveting field.

In Situ Synchrotron X-ray Diffraction Studies of Hydrogen-Desorption Properties of 2LiBH4-Mg2FeH6 Composite.

Adding a secondary complex metal hydride can either kinetically or thermodynamically facilitate dehydrogenation reactions. Adding Mg2FeH6 to LiBH4 is energetically favoured, since FeB and MgB2 are formed as stable intermediate compounds during dehydrogenation reactions. Such "hydride destabilisation" enhances H2-release thermodynamics from H2-storage materials. Samples of the LiBH4 and Mg2FeH6 with a 2:1 molar ratio were mixed and decomposed under three different conditions (dynamic decomposition under vacuum, dynamic decomposition under a hydrogen atmosphere, and isothermal decomposition). In situ synchrotron X-ray diffraction results revealed the influence of decomposition conditions on the selected reaction path. Dynamic decomposition of Mg2FeH6-LiBH4 under vacuum, or isothermal decomposition at low temperatures, was found to induce pure decomposition of LiBH4, whilst mixed decomposition of LiBH4 + Mg and formation of MgB2 were achieved via high-temperature isothermal dehydrogenation.

The Importance of Precursors and Modification Groups of Aerogels in CO2 Capture.

The rapid growth of CO2 emissions in the atmosphere has attracted great attention due to the influence of the greenhouse effect. Aerogels' application for capturing CO2 is quite promising owing to their numerous advantages, such as high porosity (~95%); these are predominantly mesoporous (20-50 nm) materials with very high surface area (>800 m2∙g-1). To increase the CO2 level of aerogels' uptake capacity and selectivity, active materials have been investigated, such as potassium carbonate, K2CO3, amines, and ionic-liquid amino-acid moieties loaded onto the surface of aerogels. The flexibility of the composition and surface chemistry of aerogels can be modified intentionally-indeed, manipulated-for CO2 capture. Up to now, most research has focused mainly on the synthesis of amine-modified silica aerogels and the evaluation of their CO2-sorption properties. However, there is no comprehensive study focusing on the effect of different types of aerogels and modification groups on the adsorption of CO2. In this review, we present, in broad terms, the use of different precursors, as well as modification of synthesis parameters. The present review aims to consider which kind of precursors and modification groups can serve as potentially attractive molecular-design characteristics in promising materials for capturing CO2.

Kinetic study on electro-nucleation of water in a heterogeneous propane nano-bubble system to form polycrystalline ice Ic.

Elucidating the underlying mechanisms of water solidification in heterogeneous systems is crucially important for a panoply of applications; gaining such an understanding has also proven to be very challenging to the community. Indeed, one such example lies in clarifying the thermodynamics and kinetics of electro-crystallization in heterogeneous systems, such as micro- and nano-bubble systems. Here, we employ non-equilibrium molecular dynamics of water in heterogeneous environments experiencing direct contact with a propane gas phase at various temperatures in externally applied static electric fields, elucidating significant external-field effects in inducing poly-crystalline cubic-ice formation. This is in stark contrast with recent work on homogeneous cubic-ice electro-nucleation to produce largely fault-free single crystals. We explore the kinetics of heterogeneous cubic-ice electro-nucleation under different field intensities and thermal conditions and provide an overview of time-dependent dynamics of evolution of polycrystallinity.

Self-ordering water molecules at TiO2 interfaces: Advances in structural classification.

In the five-decade search for efficient photocatalysts to convert natural sunlight into hydrogen via photoelectrochemical (PEC) dissociation of water, the underlying physics and chemistry of PEC processes taking place at metal-oxide photocatalysts remains relatively poorly understood and is an active area of research by both theorists and experimentalists. This is surely the case for water structuring at metal-oxide surfaces, including their "self-ordering." In this work, we apply classical molecular-dynamics techniques to investigate and classify the structure and ordering of water layers at two TiO2 surfaces-anatase ⟨101⟩ and rutile ⟨110⟩. We are interested in identifying and classifying layers using local order parameters to distinguish the layered-water superstructure from bulk-like water configurations as observed in liquid water and common ice polymorphs. In particular, we look for the formation of regions with reduced molecular mobility and assess whether they are "ice-like," as has been proposed in recent interpretations in the literature, or, instead, how these interfacial-water structures might be otherwise described. We leverage quantitative and order-parameter analysis techniques to categorize the structural properties of layers of water molecules formed and compare them to both cubic and hexagonal polytypes of bulk ice I, as well as bulk liquid water. In doing so, we propose a general structural recognition/classification framework suitable for identifying and describing molecules at any condensed-state-water interface.

Controlling ionic conductivity through transprotein electropores in human aquaporin 4: a non-equilibrium molecular-dynamics study.

Electroporation is a matter of intensive ongoing research interest, and a much-neglected topic in trans-membrane proteins, particularly in view of such promising potential applications in medicine and biotechnology. In particular, selected such novel and exciting applications are predicated on controlling ionic conductivity through electro-pores. Here, we scrutinise the mechanisms of ions' electric conductivity, by means of structural rearrangements, through quasi-stable electro-pores through human-AQP4 as a well-representative prototype of trans-membrane ionic conduction, achieving exquisite control over ionic permeability manipulated by the application of intense static electric fields.

Amplitude effects on seismic velocities: How low can we go?

α-quartz is one of the most important SiO2 polymorphs because it is the basis of very common minerals, especially for seabed materials with geoscientific importance. The elastic characterization of these materials is particularly relevant when the properties governing phonon and sound propagation are involved. These studies are especially interesting for oil exploration purposes. Recently, we published a new method that constitutes to the best of our knowledge the first attempt to recreate longitudinal and transversal perturbations in a simulation box to observe their propagation through the crystal by means of a set of descriptors [D. Melgar et al., J. Phys. Chem. C 122, 3006-3013 (2018)]. The agreement with the experimental S- and P-wave velocities was rather excellent. Thus, an effort has been undertaken to deepen the particularities of this new methodology. Here, bearing in mind this encouraging initial methodology-development progress, we deepen our knowledge of the particularities of this new methodology in presenting a systematic investigation of the implementation of the perturbation source. This includes new ways of creating the perturbation, as well as analyzing the possible effects the perturbation amplitude could have on the resultant velocities. In addition, different force fields were tested to describe the interatomic interactions. The lack of dependence of the seismic velocities on the way the perturbation is created and the perturbation amplitude, and the good agreement with the experimental results are the main reasons that allow the definition of this new methodology as robust and reliable. These qualities are consolidated by the physical behavior of the calculated velocities in the presence of vacancies and under stress. The development of this method opens up a new line of research of calculating seismic velocities for geophysically relevant materials in a systematic way, with full control not only on the sample features (composition, porosity, vacancies, stress, etc.) but also on the particularities of perturbation itself, as well as determining optimal system-response metrics.

Acoustic-propagation properties of methane clathrate hydrates from non-equilibrium molecular dynamics.

Given methane hydrates' importance in marine sediments, as well as the widespread use of seabed acoustic-signaling methods in oil and gas exploration, the elastic characterization of these materials is particularly relevant. A greater understanding of the properties governing phonon, sound, and acoustic propagation would help to better classify methane-hydrate deposits, aiding in their discovery. Recently, we have published a new nonequilibrium molecular-dynamics (NEMD) methodology to recreate longitudinal and transverse perturbations, observing their propagation through a crystalline lattice by various metrics, to study the underlying S- and P-wave velocities (achieving excellent agreement with experiment) [Melgar et al., J. Phys. Chem. 122(5), 3006-3013 (2018); ibid.150, 084101 (2019)]. Here, we apply these NEMD methods to methane-clathrate systems to study acoustic-propagation characteristics, as well as the lattice elastic behavior. In so doing, we determine S- and P-wave velocities in excellent accord with experiment; we also ascertain the allowable magnitude range of acoustic perturbation and establish a threshold for lattice breakup and hydrate decomposition. Interestingly, upon dissociation, we observe the formation of methane nanobubbles, which agrees with previous studies on the microscopic fundamentals of hydrate dissociation by various means.

A New Relatively Simple Approach to Multipole Interactions in Either Spherical Harmonics or Cartesians, Suitable for Implementation into Ewald Sums.

We present a novel derivation of the multipole interaction (energies, forces and fields) in spherical harmonics, which results in an expression that is able to exactly reproduce the results of earlier Cartesian formulations. Our method follows the derivations of Smith (W. Smith, CCP5 Newsletter 1998, 46, 18.) and Lin (D. Lin, J. Chem. Phys. 2015, 143, 114115), who evaluate the Ewald sum for multipoles in Cartesian form, and then shows how the resulting expressions can be converted into spherical harmonics, where the conversion is performed by establishing a relation between an inner product on the space of symmetric traceless Cartesian tensors, and an inner product on the space of harmonic polynomials on the unit sphere. We also introduce a diagrammatic method for keeping track of the terms in the multipole interaction expression, such that the total electrostatic energy can be viewed as a 'sum over diagrams', and where the conversion to spherical harmonics is represented by 'braiding' subsets of Cartesian components together. For multipoles of maximum rank n, our algorithm is found to have scaling of n 3.7 vs. n 4.5 for our most optimised Cartesian implementation.

Mechanisms of Iodide⁻Triiodide Exchange Reactions in Ionic Liquids: A Reactive Molecular-Dynamics Exploration.

Efficient charge transport has been observed in iodine-doped, iodide-based room-temperature ionic liquids, yielding high ionic conductivity. To elucidate preferred mechanistic pathways for the iodide ( I - )-to-triiodide ( I 3 - ) exchange reactions, we have performed 10 ns reactive molecular-dynamics calculations in the liquid state for 1-butyl-3-methylimidazolium iodide ([BMIM][I]) at 450 to 750 K. Energy-barrier distributions for the iodine-swapping process were determined as a function of temperature, employing a charge-reassignment scheme drawn in part from electronic-structure calculations. Bond-exchange events were observed with rate-determining energy barriers ranging from ~0.19 to 0.23 ± 0.06 eV at 750 and 450 K, respectively, with an approximately Arrhenius temperature dependence for iodine self-diffusivity and reaction kinetics, although diffusion dominates/limits the bond-exchange events. This charge transfer is not dissimilar in energetics to those in solid-state superionic conductors.

Elucidating mysteries of phase-segregated membranes: mobile-lipid recruitment facilitates pores' passage to the fluid phase.

Phase segregation of multicomponent lipid bilayers leads to, under phase-coexistence conditions, domain formation, featuring delimitation by essentially one-dimensional borders. (Micro-)phase segregation of bilayers is proposed to influence the physiological behaviour of cell membranes and provides the driving force for lipid-raft formation. Experiments show a maximum in the electrical-conductivity of membranes at the phase-transition point, which has been conjectured to arise from border-nucleated transmembrane-conducting defects or pores. However, recent electroporation experiments on phase-segregated bilayers demonstrate electro-pore detection in the liquid disordered phase (Ld), wherein they diffuse over macroscopic periods without absorption into the liquid ordered phase (Lo). Here, we scrutinise transmembrane-pore formation via molecular dynamics simulations on a multicomponent phase-segregated bilayer. We find that pores created in Lo domains always migrate spontaneously to the Ld phase, via 'recruitment' of unsaturated lipids to the pore's rim to transport the pore to the fluid phase under a large stress-field driving force. Once in Ld domains, pores migrate towards their centre, never returning or pinning to Lo. These findings are explained by thermodynamics. By comparing the free-energy cost for creating pores in the bulk of Ld and Lo membranes, and in the phase-segregated system, we show that it is always more energetically tractable to create pores in Ld domains, independent of the pore size.

Electro-nucleation of water nano-droplets in No Man's Land to fault-free ice Ic.

Elucidating water-to-ice freezing, especially in "No Man's Land" (150 K < T < 235 K), is fundamentally important (e.g., predicting upper-troposphere cirrus-cloud formation) - and elusive. An oft-neglected aspect of tropospheric ice-crystallite formation lies in inevitably-present electric fields' role. Exploring nucleation in No Man's Land is technically demanding, owing to rapid nucleation rates, to mention nothing of difficulties of applying relevant electric fields thereto. Here, we tackle these intriguing open questions, via non-equilibrium molecular-dynamics simulations of sub-microsecond formation of rhombus-shaped ice Ic nano-crystallites from aggressively-quenched supercooled water nano-droplets in the gas phase, in external static electric fields. We explore droplets' nano-confined geometries and the entropic-ordering agent of external electric fields as a means of realising cubic-ice formation, especially with very few stacking faults and defects.

Pressure dependence of structural properties of ice VII: An ab initio molecular-dynamics study.

The observed anomalous self-diffusivity of ice VII in the region of 10 GPa at ∼400 K has been suggested to arise from a change in proton-hopping mechanism involving a transition from ionic-defect-driven diffusivity to that dominated by diffusion of rotational defects. Here, we report ab initio molecular dynamics to study the structural, hydrogen bonding, electronic, vibrational, and Raman properties of ice VII at this temperature and between 5 and 20 GPa to elucidate any possible hints of intramolecular strain that may serve as precursor events for proton hopping to unfold. We determine such equilibrium properties to be in reasonable agreement with experimental Raman spectra, although we do not detect any water-dissociation and proton-hopping events per se, owing to still-large water-dissociation free-energy barriers.

Non-equilibrium molecular-dynamics study of electromagnetic-field-induced propane-hydrate dissociation.

Non-equilibrium molecular-dynamics simulations have been performed for dissolution of planar propane-hydrate/water interfaces in externally-applied electromagnetic (e/m) fields in the microwave to far infrared range (∼2.45-200 GHz) at electric-field intensities up to 2.0 V/nm and at roughly 20 K over/under temperatures vis-à-vis the zero-field propane-hydrate melting point. Upon e/m-field application, there is a field-frequency threshold above which the dissociation rate drops significantly, with a plateau therein for larger-frequencies. It was found that higher intensity and lower frequency facilitates dissociation. Except in the presence of a thermal driving-force, the 10 GHz frequency shows more substantial rate-enhancement effect vis-à-vis static electric fields or, indeed, lower-frequency e/m fields.