Formation Equilibria Research Articles

Bi-level real-time pricing model in multitype electricity users for welfare equilibrium: A reinforcement learning approach

The diverse load profile formation and utility preferences of multitype electricity users challenge real-time pricing (RTP) and welfare equilibrium. This paper designs an RTP strategy for smart grids. On the demand side, it constructs utility functions reflecting user characteristics and uses multi-agents for different user interests. Considering industrial users, small-scale microgrids, distributed generation, and battery energy storage systems are included. Based on supply and demand interest, a distributed online multi-agent reinforcement learning (RL) algorithm is proposed. A bi-level stochastic model in the Markov decision process framework optimizes the RTP strategy. Through information exchange, an adaptive pricing scheme balances interest and achieves optimal strategies. Simulation results confirm the effectiveness of the proposed method and algorithm in peak shaving and valley filling. Three load fluctuation scenarios are compared, showing the algorithm's adaptability. The findings reveal the potential of the RL-based bi-level pricing model in resource allocation and user benefits in smart grids. Innovations in user modeling, model construction, and algorithm application have theoretical and practical significance in the electricity market research.

Properties of Pickering Stabilized Associative Water‐In‐Water Emulsions Based on Ultra‐High Molecular Weight Polyacrylamides

AbstractCompletely water‐based multicompartment systems have attracted a broad interest in recent years, mainly due to their versatile features such as permeability. Here, the associative formation of water‐in‐water (w/w) emulsions based on ultra‐high molecular weight poly(N,N‐dimethylacrylamide) (PDMA) and poly(4‐acryloylmorpholine) (PAM) is studied. The system is investigated using a combination of fluorescence microscopy and spectroscopy techniques. The system phase‐separates into aqueous droplets at very low polymer concentrations and exhibits intriguing physical properties. The formed emulsion droplets are extremely fluid (5–10 mPa.s), enable fast (5 µm2 s−1), nearly complete (mobile fraction ≈0.8) and unhindered diffusion within and across compartments, which is a hallmark of fluids. Furthermore, the very low interfacial tension (0.18–0.40 mN m−1) enables droplet coalescence leading to equilibrium formation of various emulsion structures. These properties show similarities to cell cytoplasm and coacervates and hence this type of w/w emulsion formed via associative non‐ionic interactions is a new direction in the field of synthetic cells and synthetic biology.

Influence of Transfer Epidemiological Processes on the Formation of Endemic Equilibria in the Extended SEIS Model

In the present paper, a modification of the standard mean-field model is considered, allowing for the description of the formation of a dynamic equilibrium between infected and recovered persons in a population of constant size. The key point of this model is that it highlights two-infection transfer mechanisms depending on the physical nature of the contact between people. We separate the transfer mechanism related directly to the movement of people (the so-called transport processes) from the one occurring at zero relative speed of persons (the so-called social contacts). Under the framework of a physical chemical analogy, the dependencies for the infection transfer rate constants are proposed for both purely transport and social mechanisms of spread. These dependencies are used in discussing the formation of quasi-stationary states in the model, which can be interpreted as endemic equilibrium states. The stability of such endemic equilibria is studied by the method of Lyapunov function.

First-Principles study of Ti-Based X2TiH5 (X = Mg, Ca, Sr) hydrides for Advanced hydrogen storage applications

The potential solution to the urgent issue of hydrogen storage in mobile applications is in the potential contribution of solid materials. Moreover, extensive study has been carried out on perovskite hydride materials to improve their efficiency in the field of hydrogen storage. The present work focuses on the computational investigation of X2TiH5 (X = Mg, Ca, and Sr) perovskite-type hydrides, taking into account diverse physical properties and their potential uses in hydrogen storage. The thermodynamic stability of X2TiH5 (X = Mg, Ca, and Sr) was assessed by analyzing their negative formation equilibrium. The compounds exhibiting tetragonal structures with Sr2TiH5 have the highest computed lattice constants, namely a = b = 5.69 Å and c = 7.91 Å. The electrical properties unequivocally indicate that the molecules being investigated have a metallic nature. Furthermore, the metallic hydrides provide promising possibilities as potential contenders for hydrogen storage applications. Furthermore, the optical properties of all the compounds were quantified. Finally, the calculated hydrogen storage capacities are 4.97 wt% for Mg2TiH5, 3.78 wt% for Ca2TiH5 and 2.21 wt% for Sr2TiH5. This study demonstrated X2TiH5 (X = Mg, Ca and Sr) have the potential for hydrogen storage, although Mg2TiH5 and Ca2TiH5 are the only compounds that meets the US-DOE criterion for 2020.

Incorporation of cerium oxide nanoparticles into the micro-arc oxidation layer promotes bone formation and achieves structural integrity in magnesium orthopedic implants

Biodegradable metals offer significant advantages by reducing the need for additional surgeries following bone fixation. These materials, with their optimal mechanical and degradable properties, also mitigate stress-shielding effects while promoting biological processes essential for healing. This study investigated the in vitro and in vivo biocompatibility of ZK60 magnesium alloy coated with a micro-arc oxidative layer incorporated with cerium oxide nanoparticles in orthopedic implants. The results demonstrated that the magnesium substrate undergoes gradual degradation, effectively eliminating long-term inflammation during bone formation. The micro-arc oxidative coating forms a dense ceramic layer, acting as a protective barrier that reduces corrosion rates and enhances the biocompatibility of the magnesium substrate. The incorporation of cerium oxide nanoparticles improves the tribological properties of the coating, refining degradation patterns and improving osteogenic characteristics. Furthermore, cerium oxide nanoparticles enhance bone reconstruction by facilitating appropriate interconnections between newly formed bone and native bone tissue. Consequently, cerium oxide nanoparticles contribute to favorable biosafety outcomes and exceptional bone remodeling capabilities by supporting bone healing and sustaining a prolonged degradation process, ultimately achieving dynamic equilibrium in bone formation. Statement of significanceThis study comprehensively examined the incorporation of cerium oxide nanoparticles into biodegradable magnesium through a micro-arc oxidative process for use in orthopedic implants. This study conducted a comprehensive analysis involving material characterization, biodegradability testing, in vitro osteogenesis assays, and in vivo implantation, highlighting the potential benefits of the distinctive properties of cerium oxide nanoparticles. This research emphasizes the ability of cerium oxide nanoparticles to enhance the biodegradability of magnesium and facilitate remarkable bone regeneration, suggesting promising advantages for additive materials in orthopedic implants.

Predictive calculation of the stability constants of silver(I) ion with pyridine and 2,2′-bipyridyl in a solvent environment

In the present study, the stability constants of silver(I) coordination compounds with 2,2′-bipyridyl (bpy, L) in mixed methanol–acetonitrile solvents (MeOH-AN, χAN = 0.0 ÷ 1.0 mol fr.) were determined by the potentiometric method at 25.0 °C. The influence of reagents solvation on the change in stability of [Ag(bpy)]+ and [Ag(bpy)2]+ complexes upon changing the composition of the solvent MeOH→(MeOH-AN) was analyzed. It has been established that the determining factor in the shift of the complex formation equilibrium along the first and second steps of coordination with a change in the composition of the solvent is the contribution from the central ion resolvation. The obtained results and data on the thermodynamics of complex formation reactions of Ag+ with bpy and pyridine (py, L) in a few binary non-aqueous solvents were compared. The possibility of carrying out an estimated calculation of the stability constants of [Ag(L)]+ in non-aqueous solvents was confirmed.

Formation kinetics and equilibrium thermodynamics study on the Bi2O3-TiO2 system for synthesis of the bismuth titanate ceramics

Formation kinetics and equilibrium thermodynamics are fundamental knowledge for predicting microstructure and properties during materials processing and utilization. This work prepared high purity Bi12TiO20, Bi4Ti3O12 and Bi2Ti4O11 compounds and characterized these compounds by in-suit X-ray diffraction, scanning electron microscope, energy dispersive spectrometer as well as calorimetry. Based on the experimental data obtained in this work and the literature, a thermodynamic description of the Bi2O3–TiO2 system was carried out, a thermodynamic database as well as the calculated phase diagram of the system was provided. The discrepancy between the present calculation with the experimental data were discussed, the formation kinetics of the compounds was explained and the bismuth titanate ceramics with tailored structure and specific physical properties were sintered.

Positively charged residues play a significant role in enhancing the antibacterial activity of calcitermin

A systematic study on the human antimicrobial peptide calcitermin (VAIALKAAHYHTHKE) and its carefully designed derivatives was undertaken to verify the impact of divalent copper and zinc ions on the stability, coordination and antimicrobial activity of the formed complexes. In this work we investigate the calcitermin mutants where the alanine in position 7 and 8 is substituted with an arginine residue, with the aim of enhancing the antibacterial activity. Additionally, the analogue where alanine in position 7 is replaced with a histidine is considered, to obtain a chelating sequence with four histidines in alternate position; the aim of this change was to increase the cationic properties of the peptide under acidic conditions and possibly enhance its binding ability towards the metal ions. Through a comprehensive analytical approach involving potentiometric titrations, mass spectrometry, UV–Vis spectrophotometry, NMR and circular dichroism, we delved into the formation equilibria and coordination chemistry of the formed copper(II) and zinc(II) complexes. Antimicrobial assays are also performed to assess the bioactivity of the compounds against a broad spectrum of microorganisms, revealing the pivotal role of positively charged residues in enhancing the antibacterial activity of calcitermin. The obtained results serve as an important stepping stone towards the development of novel metal-based antimicrobial agents.

Phase transition in the shape memory alloy NiTi described by the SCAN meta-GGA functional.

Climbing the ladder of density functional approximations has long been proposed to systematically improve the accuracy of first-principles calculations employing the density functional theory (DFT); however, up until now, the Perdew-Burke-Ernzerhof (PBE) functional at the second rung of the ladder, has dominated. Here, we present a study of the martensitic phase transition in NiTi based on abinitio molecular dynamics simulations and thermodynamic integration using the third-rung approximation of the strongly constrained and appropriately normalized (SCAN) meta-generalized gradient approximation (GGA). Although the predicted equilibrium lattice constants and formation enthalpy agree well with experimental data, the martensitic transition temperature (MTT) is overestimated by 94% (or 324K too high), compared with only 22% (77K) overestimation by PBE. The latent heat (q) is severely overestimated by SCAN as well. This deteriorated performance originates from the enlarged energy difference (ΔE) between the austenite and martensite phases, compared with the PBE result. Furthermore, a large variation (over 50meV/atom) in ΔE using different meta-GGAs indicates large variations in computed MTTs (∼400-500 K) and q, i.e., the predicted thermodynamic properties depend sensitively on the choice of meta-GGA. This would pose a serious problem when upgrading DFT calculations to the third rung. One possible solution is to add NiTi as a normsystem so that the revised SCAN meta-GGA could reproduce the PBE results of the relevant energy difference.

Kinetics of hydrogen isotope exchange in kaolinite and the prediction of δD signature retention over geological time

Retention of the pristine hydrogen isotope composition (expressed as δD) formed during mineral formation in equilibrium with water is the basis for any paleoenvironmental reconstructions and for tracing mineral reactions using hydrogen (or H and O) isotope composition in kaolinite. Not only do post-formation reactions cause partial equilibration with ambient water, altering the pristine signature, but also result in the decoupling of H and O diffusion.In this study, kaolinite samples of different structural order (expressed, for example, as the Hinckley Index) were tested for their susceptibility to H isotope exchange under D2O vapor in an open system. The H isotope exchange was detected by recording the kaolinite’s structural OH and OD stretching mode using infrared spectroscopy. A number of different in-situ and ex-situ testing protocols under diverse temperature ranges (90 °C, 125–275 °C, 300–700 °C), show consistent kinetics and mechanism. In each kaolinite sample, the H isotope exchange rate increases with temperature; however, the major control on the reaction rate is the kaolinite crystallite’s structural order, not the particle (agglomerated crystallites) size. The hydrogen isotope composition in kaolinite can be altered independently of oxygen atoms, likely via proton hopping mechanism through structural defects. The H isotope exchange reaction under vapour shows a two-mode kinetics: the time-to-the-quarter (TTTQ; t1/4) dependence dominates in the first part of the reaction or in low-temperature reactions, transitioning to the log10t (Elovich) relationship and with lower activation energy, in advanced stages and in higher temperatures. Extrapolating the TTTQ model to temperatures < 90 °C allows estimating the rate of H isotope exchange between water vapor and kaolinite. The paper presents the prediction of preservation of pristine δD signature and thus reliability of using isotope data in kaolinites of different origins and structural order when exposed to pore water / water vapor over geological timescales.

Three-Dimensional Nonlocal Thermodynamic Equilibrium Abundance Analyses of Late-Type Stars

The chemical compositions of stars encode the history of the universe and are thus fundamental for advancing our knowledge of astrophysics and cosmology. However, measurements of elemental abundance ratios, and our interpretations of them, strongly depend on the physical assumptions that dictate the generation of synthetic stellar spectra. Three-dimensional radiation-hydrodynamic (3D RHD) box-in-a-star simulations of stellar atmospheres offer a more realistic representation of surface convection occurring in late-type stars than do traditional one-dimensional (1D) hydrostatic models. As evident from a multitude of observational tests, the coupling of 3D RHD models with line formation in nonlocal thermodynamic equilibrium (non-LTE) today provides a solid foundation for abundance analysis for many elements. This review describes the ongoing and transformational work to advance the state of the art and replace 1D LTE spectrum synthesis with its 3D non-LTE counterpart. In summary: ▪3D and non-LTE effects are intricately coupled, and consistent modeling thereof is necessary for high-precision abundances; such modeling is currently feasible for individual elements in large surveys. Mean 3D (〈3D〉) models are not adequate as substitutes.▪The solar abundance debate is presently dominated by choices and systematic uncertainties that are not specific to 3D non-LTE modeling.▪3D non-LTE abundance corrections have a profound impact on our understanding of FGK-type stars, exoplanets, and the nucleosynthetic origins of the elements.

Determination of hydrate phase equilibrium (H-L-V) data for the binary CO2–CH4 gas mixture in the presence of 1,3 dioxolane

Present work details the determination of three phase hydrate equilibrium data (H-L-V) using temperature search method for the binary CO2/CH4 gas mixture (50:50 molar ratio) in presence of 1,3 dioxolane (DIOX). DIOX concentration used for phase equilibrium determination were 1,3 and 5.56 mol% respectively. In the presence of DIOX, it was observed that phase equilibrium curve was shifted right with respect to the curve using same gas mixture with no additive (pure water). This indicates that the presence of DIOX moderates the hydrate formation equilibrium conditions. Also, as DIOX concentration increases from 1 mol% to 5.56 mol%, a decrement in phase equilibrium pressure at same temperatures was observed, confirming the potential of DIOX as an effective thermodynamic promoter. Enthalpy of hydrate dissociation was calculated for CO2/CH4 gas mixture in presence of DIOX using Clausius- Clapeyron plot and it was found to be 90.81±6.55 KJ/mol which confirms the sII structure of CO2-CH4-DIOX mixed hydrate. Besides providing the phase equilibrium data of formed hydrates with CO2/CH4 gas mixture using different concentration of DIOX, the present study will aid in determining suitable experimental conditions for examining kinetics and performing separation studies of CO2/CH4 gas mixture through hydrate formation.

Abiotic and Biotic Processes Controlling Deposition of Calcite and Hydrotalcite Calcretes on Niue Island, Southwest Pacific

Calcretes are indurated terrestrial carbonates that are widespread in arid and semi-arid settings and serve as important archives of present and past environments. Here, we use geochemical tools to explore the nature and origin of calcretes documented from tropical Niue Island in the Southwest Pacific. The study recognizes two types of calcretes that differ in their mineral assemblage, microfabrics, elemental chemistry, and carbon and oxygen isotopes. The calcretes common in the paleo-lagoon soils consist of 90% low-Mg calcite and ~10% highly weathered Mg-Al silicates. These pedogenic calcretes formed in the soil profiles within the vadose zone bear the following distinctions: (i) Fe/Al ratio of 0.75, identical to the ratio in soils (Fe/Al = 0.76 ± 0.5), substantiating the link between the calcretes and soils; (ii) presence of rhizoliths, root voids, micritic nodules, and clasts, which are consistent with a pedogenic calcrete fabric; and (iii) 13C and 18O depletions of −10.6‰ and −5.3‰, respectively, which are compatible with carbon sources from microbial and root respiration, as well as formation in oxygen isotope equilibrium with vadose waters. Unlike the pedogenic calcrete, a rare calcrete from the coastal terrace contains an exceptionally rare hydrotalcite [Mg6Al2(CO3)(OH)16(H2O)4] mineral (65%) coated by microbial films. We contend that the hydrotalcite-rich calcrete was deposited through interaction of dolomite with seawater, similar to the method of producing hydrotalcite in the laboratory. 13C and 18O enrichments of 0.8 to 1.7‰ and −1.0 to −1.6‰, respectively, are in agreement with (i) mixed carbon sources consisting of microbial CO2 degassing, seawater HCO3, and dolomite dissolution, and (ii) oxygen isotope equilibration with seawater-derived fluid.

Effects of Heterogeneous Mixing of Imidazolium-Based Ionic Liquids with Alcohols on Complex Formation of Ni(II) Ion.

Understanding the complex formation of metal ions in room-temperature ionic liquids (ILs) is essential for the application of ILs in solvent extraction. Nevertheless, the research on metal complex formation in ILs lags behind other applications. The complex formation equilibria may be influenced by specific interactions among the metal ion, ligand molecule, and IL cation and anion. In the present investigation, the complex formation of Ni2+ with ethanol (EtOH) and methanol (MeOH) molecules in ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([CNmim][TFSA], where N represents the alkyl chain lengths of 2 and 8) was discussed in terms of the microscopic interactions among alcohol molecules, [CNmim]+ and [TFSA]-, and the mesoscopic mixing states of alcohols in [CNmim][TFSA], with N = 2-12. The microscopic interaction of alcohol molecules with the imidazolium ring H atoms in the ILs was evaluated by using ATR-IR and 1H and 13C NMR spectroscopies. The self-hydrogen bonding of alcohol molecules was clarified from the O-H stretching vibration of alcohol molecules. MeOH molecules can be more strongly hydrogen-bonded with themselves than EtOH molecules due to the less steric hindrance and the weaker dispersion force of MeOH with the IL cation's alkyl chain. In fact, small-angle neutron scattering (SANS) experiments revealed the more heterogeneous mixing of MeOH with the ILs by the self-hydrogen bonding among MeOH molecules than EtOH. The longer the IL cation's alkyl chain, the more the MeOH clusters significantly form. In contrast, the formation of EtOH clusters becomes weaker with elongating the alkyl chain. Ultraviolet (UV)-visible spectroscopic measurements on Ni2+-[CNmim][TFSA]-alcohol solutions with N = 2 and 8 revealed that di-, tetra-, and hexa-alcohol-Ni2+ complexes are formed in both the ILs. With N = 2, the stabilities of Ni2+-EtOH and Ni2+-MeOH complexes are comparable in the IL. However, with N = 8, the complexes are more stable in the EtOH solutions than in the MeOH solutions. This is because the less heterogeneous mixing of EtOH molecules with the IL results in the larger enthalpic contribution in the complex formation, as shown by the thermodynamic parameters estimated by the van't Hoff plots on the stability constants at several temperatures.

Economic activities, dry bulk freight, and economic policy uncertainties as drivers of oil prices: A tail-behaviour time-varying causality perspective

This paper examines the dynamic impact of economic activity, Baltic dry bulk and economic policy uncertainty on oil prices. Drawing on demand-side economic theory, we focus on how economic activity and economic policy uncertainty drive oil prices and subsequently contribute to the formation of market equilibrium. In this context, we first introduce a unidirectional quantile and time-varying Granger-causality mechanism for the drivers of oil prices. Our novel rolling window quantile Granger causality approach reveals that economic activity drives crude oil price fluctuations and highlights their important role in market imbalances. In particular, economic activity and the Baltic exchange rate index emerge as essential drivers of oil prices, confirming our hypothesis of a demand-side effect. Moreover, our robustness wavelet quantile correlation (WQC) analyses reveal that economic activity promotes oil price fluctuations along both long-term equilibrium trends and short-term dynamics. In contrast, economic policy uncertainty has a dampening effect on oil prices. More broadly, economic activity is positively correlated with the Baltic exchange dry index, highlighting its broader impact on global trade indicators. Moreover, we use a bivariate Quantile on Quantile regression method to identify the equilibrium searches of different thresholds and estimate the robustness of the validity of the WQC findings. Analyzing the quantile and frequency connectedness spillovers, we observe that shocks from economic activity are particularly pronounced in the tail quantiles, reinforcing the demand-side narrative. Overall, the increased risk in extreme tails underscores the increased interaction between economic activity, oil prices and economic policy uncertainties. Our findings have important implications for policymakers and highlight the need for adaptive strategies to manage potential oil price shocks. Thus, by adopting a demand-side perspective, policymakers can better anticipate and respond to oil price fluctuations, promoting more resilient economic policies.

Excited-State Dynamics of a Bright Fluorescent Dye with Precise Control of Emission Color Using Acid-Base Equilibrium, Intramolecular Charge Transfer, and Host-Guest Chemistry.

A fluorescent dye, a dithiophene-conjugated benzothiazole derivative (DTBz), was prepared to have high fluorescence emission quantum yields (ΦF) across various organic solvents. Its emission color modulation, from bright blue to deep red, was achieved through intramolecular charge transfer (ICT), acid-base equilibrium, and host-guest chemistry. Although it exhibits a weak solvatochromic effect, DTBz exhibited a bright fluorescence emission around 480 nm upon excitation at 390 nm in most solvents. In polar solvents, such as MeOH (methanol), EtOH (ethanol), DMF (N,N-dimethylforamide), and DMSO (dimethyl sulfoxide), an additional ICT emission band emerged around 640 nm, notably intense in DMSO, resulting in a bright greenish-white emission (ΦF = 0.67). The addition of 1,8-diazabicyclo[5,4.0]undec-7-ene (DBU) altered emission characteristics, reducing emission from the local excited (LE) state and enhancing ICT state emission. The degree of emission spectral change saturation with DBU addition varied with the solvent nature. Polar solvents with high dielectric constants, like DMSO and DMF, saw a complete disappearance of LE state emission with 5 equiv of DBU, resulting in a deep red emission (ΦFs of 0.53 and 0.48, respectively). Femtosecond transient absorption spectroscopy and time-resolved photoluminescence measurements elucidated the excited-state dynamics, revealing a long-lived excited state (τ-H = 10.3 ns) at a lower energy emission (640 nm), identified as DTBz-*, supported by transient absorption spectra analysis. Further analysis, including time-resolved fluorescence decay measurements and time-dependent density-functional theory (TD-DFT) calculations, underscored the role of deprotonation of DTBz's hydroxyl group in promoting the ICT process. The CIE coordination plot demonstrated wide linear emission color changes upon successive DBU additions in all solvents, while emission color precision was achieved through host-guest chemistry. Emission changes induced by DBU were reverted to the original state upon beta-cyclodextrin (β-CD) addition, with the 1H NMR study revealing the competition between acid-base equilibrium and host-guest complex formation as the cause of emission color change.

The role of an in-plane electric field during the merging formation of spherical tokamak plasmas

Axial merging of two torus plasmas is utilized as a center-solenoid free start-up scheme for a high-beta spherical tokamak (ST) plasma, in which magnetic reconnection under a strong guide field plays dominant roles in energy conversion and equilibrium formation. The ion heating source in magnetic reconnection is the plasma outflow with E×B drift velocity in the downstream region where the reconnected field lines flow out. Since the inductive reconnection electric field is almost parallel to the magnetic field, particularly in the inboard-side downstream region of magnetic reconnection under a strong guide field, a large electrostatic field in the poloidal plane is spontaneously formed to sustain steady plasma outflow motion in the downstream region. In ST plasma merging experiments, the self-generated electrostatic field in the downstream region does not always balance with the inductive electric field to make the total electric field strictly perpendicular to the total magnetic field. The excess electrostatic field will provide an even faster outflow plasma velocity than the magnetic field line motion and a quick reversal of the toroidal plasma current to form convex flux surfaces.

Interactions and pattern formation in a macroscopic magnetocapillary SALR system of mermaid cereal

When particles are deposited at a fluid interface they tend to aggregate by capillary attraction to minimize the overall potential energy of the system. In this work, we embed floating millimetric disks with permanent magnets to introduce a competing repulsion effect and study their pattern formation in equilibrium. The pairwise energy landscape of two disks is described by a short-range attraction and long-range repulsion (SALR) interaction potential, previously documented in a number of microscopic condensed matter systems. Such competing interactions enable a variety of pairwise equilibrium states, including the possibility of a local minimum energy corresponding to a finite disk spacing. Two-dimensional (2D) experiments and simulations in confined geometries demonstrate that as the areal packing fraction is increased, the dilute repulsion-dominated lattice state becomes unstable to the spontaneous formation of localized clusters, which eventually merge into a system-spanning striped pattern. Finally, we demonstrate that the equilibrium pattern can be externally manipulated by the application of a supplemental vertical magnetic force that remotely enhances the effective capillary attraction.

Fluorescence lifetime nanothermometer based on the equilibrium formation of anthracene AIE-excimers in living cells

The effective measurement of temperature in living systems at the nano and microscopic scales continues to be a challenge to this day. Here, we study the use of 2-(anthracen-2-yl)-1,3-diisopropylguanidine, 1, as a nanothermometer based on fluorescence lifetime measurements and its bioimaging applications. In aqueous solution, 1 is shown in aggregated form and the equilibrium between the two main aggregate types (T-shaped and π-π) is highly sensitive to the temperature. The heating of the medium shifts the equilibrium toward the formation of highly emissive T-shaped aggregates. This species shows a high fluorescence emission and a long lifetime in comparison with the π-π aggregates and the freé monomer. A linear relationship between the fluorescence lifetime and the temperature both in aqueous solution and in a synthetic intracellular buffer was found. Fluorescence lifetime imaging microscopy (FLIM) also showed a linear relationship between lifetime and temperature with an excellent sensitivity in MCF7 breast cancer cells, which opens the door for its potential use as FLIM nanothermometer in the biomedical field.

Nitrogen isotope homogenization of dissolved ammonium with depth and 15N enrichment of ammonium during incorporation into expandable layer silicates in organic-rich marine sediment from Guaymas Basin, Gulf of California

Sedimentary nitrogen isotopic ratios are used as a proxy for ancient biogeochemical cycles on Earth's surface. It is generally accepted that sediment hole tops record primary signatures because organic nitrogen (ON) is predominant in this part of the hole. In contrast to such early to middle diagenetic stages, it is well known that heavier nitrogen isotope 15N tends to enrich in sedimentary rocks during later diagenetic and metamorphic stages. However, there are some critical gaps in our understanding of nitrogen isotopic alteration associated with abiotic processes during early-middle diagenesis. In this study, we examined the isotope ratios of ammonium nitrogen in interstitial water (IW) and total nitrogen (TN), including exchangeable ammonium and mineral nitrogen, in the solid-phase of organic-rich-sediment recovered by International Ocean Discovery Program (IODP) Expedition 385 cores drilled in the Guaymas Basin, Gulf of California, that contained ammonium-rich IW. The isotopic ratios (δ15N value) of TN are the most variable with depth compared to any other type of nitrogen. This variation can be interpreted as reflecting changes in the water mass environment in the basin caused by glacial–interglacial climate changes, modifying the δ15N values of the marine primary producers. Thus, the δ15N value of TN is a proxy for environmental change in the basin, while each component of TN shows different trends. The δ15N values of IW and exchangeable ammonium did not exhibit significant changes with depth, but the latter values are about 3 ‰ enriched in 15N. This may be due to advective transport of solute into adjacent layers followed by the formation of an isotopic equilibrium between IW and exchangeable ammonium in the case of fast sediment accumulation rate. The δ15N value of exchangeable ammonium is the highest among the other types of nitrogen with one exception, where the δ15N value of TN is the highest. The calculated δ15N values of ON based on mass balance are almost the same as those of associated TN in the shallow sediment layers (< 150 m below seafloor), but the difference in the δ15N values of TN and ON are significant in the deeper layers, where proportions of ON contents are <50%. In particular, in the layer where the δ15N value of TN is the highest, that of ON shows an even higher value and the difference reaches 3.5 ‰. The δ15N values of mineral nitrogen are similar to that of IW ammonium except the surface layers. Under such conditions, when δ15N value of TN is intermediate between those of mineral nitrogen and exchangeable ammonium, calculated δ15N value of ON is close to that of TN. On the other hand, if δ15N value of TN is out of the range between mineral nitrogen and exchangeable ammonium, it causes further difference in δ15N value of ON. It means that the fluctuation of δ15N values of TN is reduced relative to those of ON through depth. It has been considered that δ15N value of TN in sediment is similar to that of ON, and changes in the δ15N value of TN due to diagenesis are limited, but in such environment ON fluctuations over depth may be slightly underestimated.