Liquid Formation Research Articles

Evaluating liquid CO2 hydrate formation kinetics, morphology, and stability in oceanic sediments on a lab scale using top injection

Storing captured CO2 into the deep oceanic sediments as CO2 hydrates offers a potential approach to reducing atmospheric carbon emissions. However, two major challenges are slow CO2 hydrate formation kinetics and lack of an understanding of CO2 hydrate stability dynamics. To counter these challenges, the conversion of high-pressure liquid CO2 (LCO2) to CO2 hydrates has been experimentally explored [with and without a hydrate kinetic promoter L-tryptophan] in a lab-scale reactor embedded with an artificial seabed. The stability of these CO2 hydrates was also evaluated by submerging them in the aqueous phase (mimicking hydrostatic pressure of fluid) at thermodynamic conditions found at an oceanic depth of 1 km [3–4 °C, 10 MPa] for 14 days. In-situ high-pressure Raman spectroscopy was used to estimate the real-time solubility of CO2 in the aqueous medium, and an image processing thresholding technique was used for detecting CO2 hydrate formation/dissociation patterns in sediments during the stability testing.The lab-scale experimental results indicate that in comparison to gaseous CO2, the liquid CO2 forms hydrates much faster [60 times] in the sediments. These CO2 hydrates exhibited decent stability over 14 days when submerged in an aqueous medium [3–4 °C, 10 MPa]. At the end of the stability test, hydrates were dissociated by thermal stimulation to assess the CO2 hydrates inside the sediments qualitatively. A significant decrease in the height of the sand bed [6.0 cm to 5.5 cm] and the evolution of CO2 across the sediments confirmed the presence of a good number of hydrates inside the sediments.

Novel Covalent Modifier-Induced Local Conformational Changes within the Intrinsically Disordered Region of the Androgen Receptor.

Intrinsically disordered regions (IDRs) of transcription factors play an important biological role in liquid condensate formation and gene regulation. It is thus desirable to investigate the druggability of IDRs and how small-molecule binders can alter their conformational stability. For the androgen receptor (AR), certain covalent ligands induce important changes, such as the neutralization of the condensate. To understand the specificity of ligand-IDR interaction and potential implications for the mechanism of neutralizing liquid-liquid phase separation (LLPS), we modeled and performed computer simulations of ligand-bound peptide segments obtained from the human AR. We analyzed how different covalent ligands affect local secondary structure, protein contact map, and protein-ligand contacts for these protein systems. We find that effective neutralizers make specific interactions (such as those between cyanopyrazole and tryptophan) that alter the helical propensity of the peptide segments. These findings on the mechanism of action can be useful for designing molecules that influence IDR structure and condensate of the AR in the future.

Sequence-Tunable Phase Behavior and Intrinsic Fluorescence in Dynamically Interacting Peptides.

A conceptual framework towards understanding biological condensed phases is emerging, derived from biological, biomimetic, and synthetic sequences. However, de novo peptide condensate design remains a challenge due to an incomplete understanding of the structural and interactive complexity. We designed peptide modules based on a simple repeat motif composed of tripeptide spacers (GSG, SGS, GLG) interspersed with adhesive amino acids (R/H and Y). We show, using sequence editing and a combination of computation and experiment, that n→π* interactions in GLG backbones are a dominant factor in providing sufficient backbone structure, which in turn regulates the water interface, collectively promoting liquid droplet formation. Moreover, these R(GLG)Y and H(GLG)Y condensates unexpectedly display sequence-dependent emission that is a consequence of their non-covalent network interactions, and readily observable by confocal microscopy.

Sequence‐Tunable Phase Behavior and Intrinsic Fluorescence in Dynamically Interacting Peptides

AbstractA conceptual framework towards understanding biological condensed phases is emerging, derived from biological, biomimetic, and synthetic sequences. However, de novo peptide condensate design remains a challenge due to an incomplete understanding of the structural and interactive complexity. We designed peptide modules based on a simple repeat motif composed of tripeptide spacers (GSG, SGS, GLG) interspersed with adhesive amino acids (R/H and Y). We show, using sequence editing and a combination of computation and experiment, that n→π* interactions in GLG backbones are a dominant factor in providing sufficient backbone structure, which in turn regulates the water interface, collectively promoting liquid droplet formation. Moreover, these R(GLG)Y and H(GLG)Y condensates unexpectedly display sequence‐dependent emission that is a consequence of their non‐covalent network interactions, and readily observable by confocal microscopy.

Low-Frequency Ultrasound Effects on Cellulose Nanocrystals for Potential Application in Stabilizing Pickering Emulsions.

Cellulose, in the form of cellulose nanocrystals (CNCs), is a promising biomaterial for stabilizing Pickering emulsions (PEs). PEs are commonly formed using low-frequency ultrasound (LFU) treatment and impact CNC properties. The present study investigated the specific effects of LFU treatment on CNCs' chemical and physical properties. CNCs were characterized using dynamic light scattering, ζ;-potential determination, Fourier transform infrared spectroscopy, X-ray diffraction, and contact angle measurement. CNC suspensions were studied using rheological analysis and static multiple light scattering. LFU treatment broke CNC aggregates and modified the rheological behavior of CNC suspensions but did not affect the CNCs' chemical or crystallographic structures, surface charge, or hydrophilic properties. During the storage of CNC suspensions and PEs, liquid crystal formation was observed with cross-polarized light. Hypotheses related to the impact of liquid crystal CNCs on PE stability were proposed.

PRMT2 promotes HIV-1 latency by preventing nucleolar exit and phase separation of Tat into the Super Elongation Complex

The HIV-1 Tat protein hijacks the Super Elongation Complex (SEC) to stimulate viral transcription and replication. However, the mechanisms underlying Tat activation and inactivation, which mediate HIV-1 productive and latent infection, respectively, remain incompletely understood. Here, through a targeted complementary DNA (cDNA) expression screening, we identify PRMT2 as a key suppressor of Tat activation, thus contributing to proviral latency in multiple cell line latency models and in HIV-1-infected patient CD4+ T cells. Our data reveal that the transcriptional activity of Tat is oppositely regulated by NPM1-mediated nucleolar retention and AFF4-induced phase separation in the nucleoplasm. PRMT2 preferentially methylates Tat arginine 52 (R52) to reinforce its nucleolar sequestration while simultaneously counteracting its incorporation into the SEC droplets, thereby leading to its functional inactivation to promote proviral latency. Thus, our studies unveil a central and unappreciated role for Tat methylation by PRMT2 in connecting its subnuclear distribution, liquid droplet formation, and transactivating function, which could be therapeutically targeted to eradicate latent viral reservoirs.

Estimation of liquidity formation factors in the banking sector of Russia

Estimation of liquidity formation factors in the banking sector of Russia

FTIR and NMR spectra of polymeric ionic liquids – Products of reaction between hydroxycontaining amidines and carbon dioxide

Two hydroxy-containing amidine derivatives have been synthesized by condensation of amino-alcohols such as monoethanolamine (MEA) and tris(hydroxymethyl)aminomethane (TRIS) with N,N-dimethylformamide dimethyl acetal. Their interaction with carbon dioxide, leading to the formation of polymeric ionic liquids, was studied by FTIR and NMR spectroscopy. Dilute solutions of polymeric ionic liquids are also investigated by measuring the relative viscosity during the reaction. It has been found that during interaction of MEA-based amidine with CO2 within first 60 min of reaction the intensities ratio of absorbance bands at 1644 and 1705 cm−1 dropped from 2.84 to 1.33. The linear relationship between the time of reaction and the mentioned ratio of intensities has been established. In the similar manner the changes in the intensities ratio of absorbance bands at 1696 and 1629 cm−1 can be used for monitoring the reaction between TRIS-based amidine and CO2. Solution of polymeric ionic liquid prepared by reaction of TRIS-based amidine with CO2 in i-propanol has been used for measuring molecular weight (Mw = 637, Mn= 349; Mw/Mn = 1.828) by gel-permeation chromatography.

Platinum solubility in silicate melts: The effects of sulfur (S2–), temperature, and melt composition

Platinum (Pt) solubility in silicate melt (SolPtSil) has been determined to understand its behavior in planetary magmas. However, the effect of sulfur (S) in the silicate melt on SolPtSil was paid little attention. Here we present experiments performed at 1–1.5 GPa, 1300–1700 °C, and oxygen fugacity (fO2) from IW−1.6 to IW+2.3 (IW denotes the iron–wüstite buffer) to determine SolPtSil for silicate melts with major element compositions corresponding to those of rhyolite, mid-ocean ridge basalt, high-FeO basalt, and Martian basalt. The results show that SolPtSil increases from ∼0.1 to 10 μg/g as the S content in silicate melt increases from nominally zero to ∼4000 μg/g, which indicates that Pt dissolves predominantly as Pt-sulfide species in S2–-bearing silicate melt. Our results also show that SolPtSil increases with increasing temperature and/or the silicate melt NBO/T (the ratio of non-bridging oxygens to tetrahedrally coordinated cations). Using our newly obtained SolPtSil and previous data, we developed an empirical model that describes SolPtSil as a multi-function of temperature, fO2, the silicate melt NBO/T, and the S2– content in silicate melt in the case at reducing conditions (fO2 < IW+3.5). The application of our empirical model to mantle partial melting suggests that Pt-rich alloys form only after sulfide liquid exhaustion because of the S-enhanced SolPtSil. We also applied our empirical model to predict the behavior of Pt during arc magmatic differentiation. The results agree with the observations that Pt-rich alloys formed before the saturation of sulfides in the oxidized Pual Ridge lavas. We suggest that the observed coexistence of Pt-bearing alloys and sulfide globules in oxidized arc magmas can be explained by an early formation of Pt-bearing alloys followed by a late formation of sulfide liquids. The strong effect of S2– on SolPtSil also implies that the oxidization of magmatic melts can lead to direct precipitation of Pt-bearing alloys due to the S2– to S6+ transformation, which can also be subsequently entrapped in the sulfide liquids formed later. Finally, our results show a strong effect of S2– in the silicate melt on lowering the metal–silicate melt partition coefficients of Pt, which should be considered when using Pt to trace planetary accretion and differentiation processes. Collectively, our study demonstrates an important role for S2– in controlling the behavior of Pt during planetary core–mantle–crust differentiation.

Effect of additives on densification of tabular alumina: A case of single additive doping and co-doping

The effect of doping and co-doping of oxide additives on sintering properties and microstructural features of tabular alumina is investigated. To examine the effects of single doping, 2 wt % of each of CaO, Fe2O3, SiO2 and TiO2 were added to tabular alumina fines and the samples were sintered at 1550 °C, 1600 °C and 1650 °C. Single oxide doped batches showed improved density except the samples doped with CaO. The phase analysis and microstructural results of CaO doped samples revealed the formation of calcium hexa-aluminate phases which resulted in poor density. The abnormality in grain-growth on addition of TiO2 was found to have a deteriorating effect on the strength of samples at 1650 °C despite of maximum densification. To observe the effects of co-doping of oxides, 1 wt % of each of CaO, Fe2O3, SiO2 and TiO2 were added to tabular alumina in unique combinations under same sintering conditions. Co-doping of oxides was found to be effective in property development of samples at higher sintering temperatures. The characteristics of secondary phases so formed influenced the properties of tabular alumina through liquid phase sintering, abnormal grain growth or decreasing the bulk density of samples. The strength value increases with temperature, more prominently for samples with liquid phase formation, but decreases for samples with abnormal grain growth and hexagonal shaped secondary phase formation.

Double-Shock Compression Pathways from Diamond to BC8 Carbon.

Carbon is one of the most important elements for both industrial applications and fundamental research, including life, physics, chemistry, materials, and even planetary science. Although theoretical predictions on the transition from diamond to the BC8 (Ia3[over ¯]) carbon were made more than thirty years ago, after tremendous experimental efforts, direct evidence for the existence of BC8 carbon is still lacking. In this study, a machine learning potential was developed for high-pressure carbon fitted from first-principles calculations, which exhibited great capabilities in modeling the melting and Hugoniot line. Using the molecular dynamics based on this machine learning potential, we designed a thermodynamic pathway that is achievable for the double shock compression experiment to obtain the elusive BC8 carbon. Diamond was compressed up to 584GPa after the first shock at 20.5 km/s. Subsequently, in the second shock compression at 24.8 or 25.0 km/s, diamond was compressed to a supercooled liquid and then solidified to BC8 in around 1ns. Furthermore, the critical nucleus size and nucleation rate of BC8 were calculated, which are crucial for nano-second x-ray diffraction measurements to observe BC8 carbon during shock compressions. The key to obtaining BC8 carbon lies in the formation of liquid at a sufficient supercooling. Our work provides a feasible pathway by which the long-sought BC8 phase of carbon can be reached in experiments.

Fence-Line Spectroscopic Measurements Suggest Carry-Over of Salt-Laden Aerosols into Flare Systems Is Common.

Pollutant emissions from gas flares in the upstream oil and gas (UOG) industry can be exacerbated by aerosols of coproduced liquid hydrocarbons and formation water that survive separation and enter the flare. Of noteworthy concern is the potential impact of salt-laden aerosols, since the associated chlorine may adversely affect combustion and emissions. Here, we use a novel approach to remotely detect carry-over of salt-laden aerosols into field-operational flares via flame emission spectroscopy targeting two of the most abundant species in produced water samples, sodium and potassium. Ninety-five UOG flares were examined during field campaigns in the Bakken (U.S.A. and Canada) and Amazon (Ecuador) basins. For the first time, carry-over of salt species into flares is definitively detected and further found to be concerningly common, with 74% of studied flares having detectable sodium and/or potassium signatures. Additional analysis reveals that carry-over strongly correlates with reported flared gas volume (positive) and well age (negative), but carry-over was also observed in flares linked to older wells and those flaring relatively little gas. Given the scale of global UOG flaring and the risk of salt-laden aerosols affecting emissions, these findings emphasize the need to review separation standards and re-evaluate pollutant emissions from flares experiencing carry-over.

Intermolecular interactions underlie protein/peptide phase separation irrespective of sequence and structure at crowded milieu

Liquid-liquid phase separation (LLPS) has emerged as a crucial biological phenomenon underlying the sequestration of macromolecules (such as proteins and nucleic acids) into membraneless organelles in cells. Unstructured and intrinsically disordered domains are known to facilitate multivalent interactions driving protein LLPS. We hypothesized that LLPS could be an intrinsic property of proteins/polypeptides but with distinct phase regimes irrespective of their sequence and structure. To examine this, we studied many (a total of 23) proteins/polypeptides with different structures and sequences for LLPS study in the presence and absence of molecular crowder, polyethylene glycol (PEG-8000). We showed that all proteins and even highly charged polypeptides (under study) can undergo liquid condensate formation, however with different phase regimes and intermolecular interactions. We further demonstrated that electrostatic, hydrophobic, and H-bonding or a combination of such intermolecular interactions plays a crucial role in individual protein/peptide LLPS.

Study of the incorporation of two types of wastes and their combined effects into red ceramics

As the population continues to grow, the consumption of natural resources for use as primary materials in civil construction also increases. In addressing the need to reduce the depletion of natural resources, a viable alternative for the production of civil construction materials involves substituting a portion of these raw materials with waste materials. This approach seeks to achieve two key objectives: the promotion of waste reuse and a reduction in the consumption of natural resources. Amongst these materials, red ceramics is one of the categories of civil construction materials that allow the incorporation of waste, since its raw material, ceramic clay, is intrinsically heterogeneous, which makes the final product capable of containing a certain number of foreign materials. Wastes to be added in ceramic masses are classified, among others, into fuel and flux wastes, and both affect the ceramic firing stage in a different way. Flux wastes facilitate the liquid phase formation and fuel wastes release heat for the process. Thus, this work's main purpose was to study the mechanical behavior of red ceramics incorporated with a mixture of fuel and flux wastes, as well as the incorporation of both separately. The ceramic bodies were prepared in 7 different compositions by uniaxial pressing and were fired at 850 °C and 1050 °C. Then, their technological properties were determined to study the combined effect of adding two different types of waste at the same time. Subsequently, their technological characteristics were assessed to investigate the synergistic impact of simultaneously introducing two distinct waste materials. This study unveiled that the drawbacks associated with the inclusion of fuel waste can be mitigated by incorporating flux waste. This has the potential to enhance the sustainability of the red ceramics industry by yielding a material with properties akin to commercial products while also valorizing two waste streams that would otherwise be wrongly disposed of.

Coupled Cycling of Carbon and Water in the Form of Hydrous Carbonatitic Liquids in the Subarc Region

AbstractThe melting behavior of subducted ophicarbonate is experimentally investigated under conditions relevant for slabs at subarc depths (2.5–6 GPa and 650–1000°C). Hydrous carbonatitic liquids appear between 900 and 950°C at 2.5 GPa, between 800 and 850°C at 4–5 GPa, and at ∼800°C over 6 GPa. Water significantly depresses the thermal stability of carbonate, which drives the formation of hydrous carbonatitic liquid at low temperatures realistic for most subduction zones. Ophicarbonate fully dehydrates prior to wet melting. From an experimental point of view, the melting of ophicarbonate is essentially equal to the fluid–present melting of magnesite–bearing wehrlite lithology (i.e., meta–ophicarbonate). In the natural subduction process, the melting of meta–ophicarbonate occurs only when external water is available assuming dehydration fluid by ophicarbonate has been efficiently expelled at shallower depths. In the framework of the previously constructed dehydration history of subducting slab, the flux melting of meta–ophicarbonate at the slab–mantle interface is examined to be feasible under majority of geothermal conditions, even in cold subduction zones. Thus, hydrous carbonatitic liquid acts as a pervasive agent to transfer carbon from the slab surface to the mantle wedge at shallow depths beneath arcs. In contrast, ophicarbonate within the slab–serpentinized mantle just undergoes dehydration, and the vast majority of carbon retained in these lithologies is likely transported deeper into the mantle.

SOSS-INTAC: a new gatekeeper of genomic integrity at the interface of transcription and R-loops

A recent Nature paper by Xu etal.1 describes an important link between RNA polymerase II promoter-proximalpausing and genome stability orchestrated by liquid droplet formation to reduce unwanted R-loop accumulation.

Structural Evolution Governs Reversible Heat Generation in Electrical Double Layers.

Electrical double layer (EDL) formation determines the reversible heat generation of supercapacitors. While classical theories suggest an exothermic nature, experiments revealed that it can be endothermic, depending on the polarization and electrolyte. Here, we perform constant-potential molecular dynamics simulations and develop a lattice gas model to explore the reversible heat of EDL formation in aqueous and ionic liquid (IL) electrolytes. Our Letter reveals that EDL formation in aqueous electrolytes exhibits endothermicity under negative polarization; it shows new complexity of endothermicity followed by exothermicity in ILs, regardless of electrode polarity. These thermal behaviors are determined by the structural evolution during EDL formation, dominated by adsorbed solvent molecules rather than ions in aqueous electrolytes but governed by "demixing" and "vacancy occupation" phenomena in ILs. This Letter provides new insights into the reversible heat of supercapacitors and presents a theoretical approach to investigating thermal behaviors involving the dynamics of EDLs.

Visualization of the Lithium Sulfur Electrochemistry

Taken advantage of a high theoretical energy density of 2567 Wh kg-1, lithium sulfur batteries (LSBs) have been considered promising candidates for next-generation energy storage systems. Tremendous efforts have been devoted to improving the battery performance by preparing smart nanostructures. However, detailed reaction mechanisms and the principles of tailoring reaction paths remain unclear. In-situ transmission electron microscopy (TEM) is a powerful technique to probe the dynamic processes of electrochemical reactions at a high spatial resolution and in real-time. Through in-situ TEM study with a solid cell, we revealed the correlation between sulfur volume expansion and the porosity of carbon nanofibers. Further, by developing an in-situ TEM equiped with a graphene-based liquid cell (GLC), where liquid electrolyte and TiN-C/S nanoparticles are encapsulated between two graphene sheets, we disclosed the nucleation and growth dynamics of solid Li2S from soluble polysulfides. Very recently, using operando optical microscopy, we found liquid sulfur droplets formation during charging at room temperature, which is much lower than the melting point of sulfur. The liquid sulfur indicates superior kinetic features from its flowing and reshaping natures. More interestingly, the preservation of liquid sulfur is strongly linked to the substrate chemistry, where solid sulfur forms from the edge of 2D materials. It is believed that in-situ microscopic investigation of sulfur cathodes would not only shed new light on understanding of reaction mechanisms but also provide fundamental guidelines to design better LSBs.

Bubble Formation and Motion in Liquids—A Review

In flotation, a bubble acts as a carrier for attached particles. The properties of the gas–liquid interface of the bubble are one of the main factors determining the bubble motion and flotation efficiency. Monitoring of the bubble motion may deliver interesting information about the state of the gas–liquid interface. In the case of pure liquids, a bubble surface is fully mobile, while the presence of surface-active substances (e.g., surfactants) causes diminishing bubble velocity due to the retardation of the interface fluidity. The theoretical prediction of the terminal velocity value for the bubble has been investigated for over a century, delivering a number of various models describing bubble motion in a liquid. This narrative review is devoted to the motion of the bubble in stagnant liquids and is divided into three main sections describing: (i) experimental techniques for tracking bubble motion, (ii) bubble motion and shape deformation in clean water, and (iii) bubble motion in solutions of surface-active substances.

Arising of magnetically induced optical birefringence in ionic liquid/dielectric systems: The case of diphenyl phosphate / bis(2-ethyl hexyl) amine

Addition of diphenyl phosphate (DPP) to bis(2-ethylhexyl) amine (BEEA) causes the proton transfer from the acidic DPP to the basic BEEA with formation of ionic liquid DPP/BEEA domains. Such mixtures show significant optical birefringence if subjected to a magnetic field. When DPP amount is increased, as highlighted by molar refraction and viscosity measurements, a structural change occurs, most probably due to the percolation of the DPP/BEEA domains. Despite of this, the intensity of the magnetically-induced birefringence monotonically depends on the amount of DPP, with no peak at any specific composition. In addition, the birefringence appears immediately after the magnetic field is switched on and immediately disappears after the magnetic field is switched off, with a reversible and reproducible on/off switching. All this suggests that this property needs to be intended as deriving from a local anisotropy, not implying big supra-molecular rearrangements. Although there is effective modelling of the induced birefringence in well-defined molecular aggregates, there is not yet a theoretical description of the phenomenon shown by the nanoheterogeneities of surfactant-based liquid mixtures. So, our findings open new ways for the comprehension of the dynamics in these liquids.