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Non‐covalent chalcogen bond (ChB) interactions have found utility in many fields, including catalysis, organic semiconductors, and crystal engineering. In this study, the transition stabilizing effects of ChB interactions of oxygen and sulfur were experimentally measured using a series of molecular rotors. The rotors were designed to form ChB interactions in their bond rotation transition states. This enabled the kinetic influences to be assessed by monitoring changes in the rotational barriers. Despite forming weaker ChB interactions, the smaller chalcogens were able to stabilize transition states and had measurable kinetic effects on the rotational barriers. Sulfur stabilized the bond rotation transition state by as much as −7.2 kcal/mol without electron‐withdrawing groups. The key was to design a system where the sulfur σ ${\sigma }$ ‐hole was aligned with the lone pairs of the chalcogen bond acceptor. Oxygen rotors also could form transition state stabilizing ChB interactions but required electron‐withdrawing groups. For both oxygen and sulfur ChB interactions, a strong correlation was observed between transition state stabilizing abilities and electrostatic potential (ESP) of the chalcogen, providing a useful predictive parameter for the rational design of future ChB systems. [ABSTRACT FROM AUTHOR]

The latest version of the SONIC code with the extended thermal force model that is capable to treat collisionality dependence of the force has been applied to the interpretative simulation of L‐mode discharge of JT‐60 U to investigate the impact of kinetic correction of the thermal force on the scrape‐off layer (SOL) plasma properties. As a first attempt, we have selected an L‐mode attached discharge #39090 (Ip = 1.6 MA, Bt = 3.1 T, and PNBI = 4.5 MW), where n‾e$$ {\overline{n}}_e $$ = 2.08 × 1019 m−3, n‾e/nGr$$ {\overline{n}}_e/{n}_{Gr} $$ = 0.392 with deuterium plasmas. It has been found that the peak values of SOL impurity density are reduced by a factor of 2, with the kinetic correction, because the thermal force is reduced by the low collisionality of SOL plasma between the X‐point and the (inner and outer) midplane. On the other hand, the profiles near the divertor plates are unaffected by the kinetic correction due to the highly collisional condition. The kinetic correction is found more pronounced for the higher charge states impurity due to the charge dependence of the parallel impurity force balance. Overall effects due to the kinetic correction on the total impurity radiation and the divertor heat load are confirmed to be a few % in the present discharge condition of JT‐60U. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of ammonia (NH3) kinetics on the ignition mechanism of dimethyl ether (DME), a topic minimally addressed in existing literature, by utilizing a hypothetical NH3 representative species with identical thermodynamic properties and atomic mass to actual NH3, yet remaining inert during reactions, thereby distinguishing the kinetic effects from thermal and dilution influences. Kinetic analysis via zero-dimensional (0D) idealized reactor calculations shows that DME ignition in the ammonia-air atmosphere is still primarily governed by peroxy kinetics, yet ammonia kinetics significantly modify the ignition reaction pathways of DME. Specifically, during the low-temperature oxidation preparation stage, ammonia oxidation yields nitrogen-containing species that (e.g., NO2, NO, NH2), through CN reactions, reduce the flux in the keto-hydroperoxides (KET) formation pathway in DME. The NH3 oxidation pathway also competes for OH radicals, which disfavors DME ignition. The rapid decomposition of KET during the low-temperature heat release (LTHR) stage emits a substantial amount of OH radicals, increasing temperature and causing the shift from chain branching to chain propagation pathways in DME oxidation, leading to significant CH2O production and decreased reaction reactivity. This shift also promotes the hydrogen‑oxygen reaction mechanism, transitioning the controlling mechanism from the KET mechanism to the hydrogen peroxide (H2O2)-loop mechanism. The LTHR stage further enhances CN reactions in the CH3 pathway, favoring NO production and increasing the flux of NO and HO2 reactions releasing OH radicals. Moreover, the ammonia oxidation pathway, characterized by HO2 radical consumption and concurrent OH radical and H2O2 generation, significantly influences the H2O2-loop system, resulting in a diminished reaction flux in the H → HO2 → H2O2 mechanism during the thermal ignition preparation stage. In summary, these findings underscore the significance of CN interactions in the NH3/DME ignition process and highlight the necessity of considering CN interactions in mixed fuels between ammonia and other high-reactivity fuels (e.g., diesel with higher carbon atoms), for accurate ignition prediction.

BackgroundThe control of edge localized modes (ELMs) is a key issue for the safety operation of ITER and future magnetic confinement fusion reactors. In recent years, extensive theoretical simulations and experimental studies have demonstrated that resonant magnetic perturbation (RMP) is a promising method for controlling edge localized modes (ELMs) in H-mode plasmas.PurposeThis study aims to investigate drift kinetic resonant effects of thermal particles on the plasma response to the applied RMP and compare with that of the fluid model for better understanding of ELMs control in HL-2A.MethodsBased on experimental plasma and RMP coil configurations in HL-2A, the MARS-F/K codes were employed to compute the drift dynamic response of plasma to RMP under high constraint mode and compared it with the results of fluid model. Further sensitivity studies were conducted on key parameters including the plasma equilibrium pressure, toroidal flow as well as the thermal particle collision effects.ResultsThe fluid response model predicts an initially relatively weak enhancement of the plasma response amplitude with the equilibrium pressure parameter βN, followed by a strong variation as βN approaches the Troyon no-wall beta limit. The latter is unphysical and is eliminated by the kinetic response model. Including kinetic response and considering particle collision, the non-adiabatic resonant contribution of trapped thermal ions is found to be significant. Neglecting the particle collision, however, the trapped thermal electron contribution becomes more pronounced.ConclusionsThe importance of considering kinetic effects for high-beta plasma response is emphasized by this study. It is important to include the non-adiabatic resonant contribution of trapped particles to the kinetic response while taking into account the particle collision effect.

Slow solar wind, sharing magnetic and plasma properties typical of fast wind, the so-called slow Alfvénic wind, has been widely observed in the heliosphere. Here, we report an analysis of the turbulent properties of a slow Alfvénic stream observed by Solar Orbiter at 0.64 AU. This solar wind stream is characterized by well distinguishable regions, namely, a main portion, an intermediate region, and a rarefaction region. Each of those intervals have been studied separately, in order to enhance similarities and differences in their turbulence properties. Coherent structures naturally emerge over different time/spatial scales and their characteristics at ion scales have been investigated. The presence of these intermittent events have been found to be closely related to kinetic features in the ion (both proton and alpha particles) velocity distribution functions, suggesting a fundamental role in the kinetic physical processes that mediate the sub-ion turbulence cascade.

This paper investigates the impact of ammonia (NH 3) kinetics on the ignition mechanism of dimethyl ether (DME), a topic minimally addressed in existing literature, by utilizing a hypothetical NH 3 representative species with identical thermodynamic properties and atomic mass to actual NH 3 , yet remaining inert during reactions, thereby distinguishing the kinetic effects from thermal and dilution influences. Kinetic analysis via zero-dimensional (0D) idealized reactor calculations shows that DME ignition in the ammonia-air atmosphere is still primarily governed by peroxy kinetics, yet ammonia kinetics significantly modify the ignition reaction pathways of DME. Specifically, during the low-temperature oxidation preparation stage, ammonia oxidation yields nitrogen-containing species that (e.g., NO 2 , NO, NH 2), through C N reactions, reduce the flux in the keto-hydroperoxides (KET) formation pathway in DME. The NH 3 oxidation pathway also competes for OH radicals, which disfavors DME ignition. The rapid decomposition of KET during the low-temperature heat release (LTHR) stage emits a substantial amount of OH radicals, increasing temperature and causing the shift from chain branching to chain propagation pathways in DME oxidation, leading to significant CH 2 O production and decreased reaction reactivity. This shift also promotes the hydrogen‑oxygen reaction mechanism, transitioning the controlling mechanism from the KET mechanism to the hydrogen peroxide (H 2 O 2)-loop mechanism. The LTHR stage further enhances C N reactions in the CH 3 pathway, favoring NO production and increasing the flux of NO and HO 2 reactions releasing OH radicals. Moreover, the ammonia oxidation pathway, characterized by HO 2 radical consumption and concurrent OH radical and H 2 O 2 generation, significantly influences the H 2 O 2 -loop system, resulting in a diminished reaction flux in the H → HO 2 → H 2 O 2 mechanism during the thermal ignition preparation stage. In summary, these findings underscore the significance of C N interactions in the NH 3 /DME ignition process and highlight the necessity of considering C N interactions in mixed fuels between ammonia and other high-reactivity fuels (e.g., diesel with higher carbon atoms), for accurate ignition prediction. • The effect of NH 3 kinetics on DME ignition is investigated. • NH 3 affects the KET kinetics and the H 2 O 2 loop sub-mechanism. • C-N interactions decrease KET pathway flux in DME oxidation. • NH 3 oxidation alters the HO 2 distribution within the H 2 O 2 loop. • C-N interactions gradually activate the NO/NO 2 conversion process. [ABSTRACT FROM AUTHOR]

The titled material crystallizes with an orthorhombic unit cell, in the P21212 space group (Nr. 18). Its crystal structure was solved and refined from powder XRD patterns. The solid framework is formed by stacked undulated sheets of inorganic nature, Fe[Fe(CN)5NO], separated by bimolecular organic pillars, [4-(3-Phenylpropyl)pyridine]2, which remain coordinated to the axial coordination sites for the iron atom. The molecules forming these pillars remain coupled through C–H⋯π and dispersive interactions between neighboring molecules. When this solid is cooled and then warmed, a reversible spin transition, from high to low spin (HS → LS), and vice versa, is observed. This transition occurs in the temperature interval of 135–165 K, with a hysteresis between them of about 30 K. That hysteresis loop appears with a pronounced asymmetry when the slopes for the HS → LS and LS → HS transitions are compared. This effect is discussed in terms of the related structural changes in the solid structure during the spin transitions. The transition was also monitored from IR and Raman spectra recorded at 80 and 300 K. Relevant information on the electronic structure for both, the LS and HS phases of this material, was derived from the corresponding XPS spectra recorded at 114 and 270 K. This contribution emphasizes the role of the nitrosyl group (NO) as an electron buffer for tuning the bonding properties of the inorganic layer at the CN 5σ orbital to make possible the observed thermally-induced SCO behavior. The thermally-induced spin transition in this solid shows an asymmetric hysteresis loop, which was ascribed to the nature of the pillar molecule. [ABSTRACT FROM AUTHOR]

• A1 formation is inhibited by air-side and fuel-side methanol addition. • Chemical effects of methanol on A1 are mainly achieved through reaction paths of CH 3 and H. • Emission indices were calculated for A1, A2 and A3. In this study, counterflow nonpremixed flame modeling was conducted to examine the effects of methanol addition on benzene (A1) formation in methyl decanoate (MD) /air flames. Methanol was added to either the fuel side or oxidant side of the counterflow flames, to explore the chemistry difference in A1 formation when different methanol addition strategies were adopted. The formation routes of A1 were emphatically analyzed, and some important polycyclic aromatic hydrocarbons (PAHs), such as naphthalene (A2) and phenanthrene (A3) were also evaluated in terms of emission index. Results show that most of A1 is produced at the downstream of MD pyrolysis zone, through the recombination reactions of C 3 radicals, while methanol is primarily to produce methyl groups within a relatively higher temperature zone. Both the air-side and fuel-side additions of methanol can decrease A1 concentration, but the former shows a more significant inhibiting effect. Methanol addition featured both dilution and chemical inhibitory effects on the formation of A1 precursors, and the dilution effect was superior to the chemical effects. The chemical inhibition on A1 formation was mainly achieved through the enhancement in the generation trend of active groups and the H-addition reaction of methyl groups. The air-side addition of methanol featured a minimal effect on A1 formation, and the reduced A1 concentration within the flames was mainly attributed to the increased radial leakage s of reactive species. Besides, both addition strategies of methanol show the inhibitory effect on A2 and A3 formation, but the change in flames with the air-side addition is relatively weaker than that of the fuel-side addition flames. [ABSTRACT FROM AUTHOR]

We reveal unique hydrogen (H‐) bonding patterns and exploit them to control the kinetics, pathways and length of supramolecular polymers (SPs). New bisamide‐containing monomers were designed to elucidate the role of competing intra‐ vs. intermolecular H‐bonding interactions on the kinetics of supramolecular polymerization (SP). Remarkably, two polymerization‐inactive metastable states were discovered. Contrary to previous examples, the commonly assumed intramolecularly H‐bonded monomer does not evolve into intermolecularly H‐bonded SPs via ring opening, but rather forms a metastable dimer. In this dimer, all H‐bonding sites are saturated, either intra‐ or intermolecularly, hampering elongation. The dimers exhibit an advantageous preorganization, which upon opening of the intramolecular portion of the H‐bonding motif facilitates SP in a consecutive process. The retardation of spontaneous self‐assembly as a result of two metastable states enables length control in SP by seed‐mediated growth. [ABSTRACT FROM AUTHOR]

We present observations during two substorms using simultaneous Time History of Events and Macroscale Interactions During Substorms satellites and all‐sky imagers to determine plasma sheet dynamics associated with substorm auroral onset beads. The multi‐satellite observations showed that the cross‐tail current decreased and the field‐aligned currents increased at the substorm auroral onset, indicating that the satellites detected an initiation of the currents being deflected to the ionosphere. For duskward‐propagating beads, the electric field was tailward, and ions were accumulated closer to the Earth than electrons. The mapped bead propagation speed was close to energetic ion drift speed. The E×B $E\times B$ and electron drift speeds increased duskward and reduced the cross‐tail current at the onset. For dawnward‐propagating beads, the electric field was equatorward/earthward, and electrons were inferred to accumulate earthward of ions. The mapped bead propagation speed was comparable to the dawnward E×B $E\times B$ and electron drift speeds. The duskward ion drift and tail current were reduced, and electrons became the dominant current carrier. We suggest that the plasma species that is responsible for the bead propagation changes with the electric field configuration and that the tail current reduction by the enhanced E×B $E\times B$ drift at onset destabilizes the plasma sheet. Ion and electron outflows substantially increased low‐energy plasma density and may have increased the role of E×B $E\times B$ drifts. The bead wavelength was comparable to ion gyroradius and thus ion kinetic effects are important for determining the wavelength. In the dawnward‐propagating event, the mode of oscillation in the plasma sheet was suggested to be the sausage‐mode flapping oscillations. Plain Language Summary: Aurora in the night sky often begins with a sudden intensification called substorms, and the auroral intensification shows a wave‐like display (beads). It is critical to understand the origin of beads for revealing the mechanism of the sudden auroral intensifications, but it has been extremely difficult to find satellite observations in space to explore the magnetospheric source region of substorms. We identified two simultaneous observations of auroral beads at the beginning substorm auroral intensification by all‐sky imagers and related plasma dynamics by the Time History of Events and Macroscale Interactions During Substorms satellites in the plasma sheet. We found that the bead structure and propagation are related to charge accumulation and fast plasma streams in the plasma sheet. The plasma flow speed coincided with the bead speed, and the charge distribution and plasma stream direction reversed when the auroral beads moved to an opposite direction, giving strong evidence of the connection between the observations at the two locations. The plasma streams reduced the electric currents in the plasma sheet, and we suggest that the current reduction destabilizes the plasma sheet and initiates the substorm auroral intensification. Key Points: Duskward beads are related to energetic ion drift. The duskward E × B and electron drifts reduced the cross‐tail current at onsetDawnward beads are related to E × B and electron drifts. The duskward ion drift and tail current were reduced at onsetSpecies involved in bead propagation changes with the electric field. Tail current reduction by enhanced E × B destabilizes the plasma sheet [ABSTRACT FROM AUTHOR]

With Venus Express magnetic field measurements at 32 Hz from 2006 to 2012, we investigate statistically the magnetic fluctuations in the near-Venusian space. The global spatial distribution of their spectral scaling features is presented in MHD and kinetic regimes. It can be observed that turbulence is a common phenomenon in the solar wind in both regimes. The solar wind MHD turbulence is modified at the Venusian bow shock; MHD turbulence is absent in the Venusian magnetosheath but present at the magnetosheath boundary layer. Pre-existing kinetic turbulence from the far upstream solar wind is modified in the near solar wind region, while kinetic turbulence can be extensively observed throughout the Venusian magnetosheath and in some regions of the induced magnetosphere. Our results reveal that, in the near-Venusian space, energy cascade can be developed at the boundary between magnetosheath and wake, and the turbulence-related dissipation of magnetic energy occurs extensively in the magnetosheath and the induced magnetosphere.

In this work, the MARS-F/K codes (Liu et al 2000 Phys. Plasmas 7 3681; Liu et al 2008 Phys. Plasmas 15 112503) are utilized to model the passive and active control of the n = 1 ( n is the toroidal mode number) resistive wall mode (RWM) in a spherical tokamak (aspect ratio A = 1.66). It is found that passive stabilization of the RWM gives a relatively small increase in normalized beta above the no-wall limit, relying on toroidal plasma flow and drift kinetic resonance damping from both thermal and energetic particles. Results of active control show that with the flux-to-voltage control scheme, which is the basic choice, a proportional controller alone does not yield complete stabilization of the mode. Adding a modest derivative action, and assuming an ideal situation without any noise in the closed-loop, the RWM can be fully stabilized with the axial plasma flow at 5% of the Alfvén speed. In the presence of sensor signal noise, success rates exceeding 90% are achieved, and generally increase with the proportional feedback gain. On the other hand, the required control coil voltage also increases with feedback gain and with the sensor signal noise.

We have developed a new global eigenvalue code, multiscale analysis for plasma stabilities (MAS), for studying plasma problems with wave toroidal mode number ( n ) and frequency ( ω ) in a broad range of interest in general tokamak geometry, based on a five-field Landau-fluid description of thermal plasmas. Beyond keeping the necessary plasma fluid response, we further retain the important kinetic effects including diamagnetic drift, ion finite Larmor radius, finite parallel electric field ( $E_{||}$ ), ion and electron Landau resonances in a self-consistent and non-perturbative manner without sacrificing the attractive efficiency in computation. The physical capabilities of the code are evaluated and examined in terms of both theory and simulation. In theory, the comprehensive Landau-fluid model implemented in MAS can be reduced to the well-known ideal magnetohydrodynamic (MHD) model, electrostatic ion-fluid model, and drift-kinetic model in various limits, which clearly delineates the physics validity regime. In simulation, MAS has been well benchmarked with theory and other gyrokinetic and kinetic-MHD hybrid codes in a manner of adopting the unified physical and numerical framework, which covers the kinetic Alfvén wave, ion sound wave, low- n kink, high- n ion temperature gradient mode and kinetic ballooning mode. Moreover, MAS is successfully applied to model the Alfvén eigenmode (AE) activities in DIII-D discharge #159243, which faithfully captures the frequency sweeping of reversed shear AE, the tunneling damping of toroidal AE, as well as the polarization characteristics of kinetic beta-induced AE and beta-induced Alfvén-acoustic eigenmode being consistent with former gyrokinetic theory and simulation. With respect to the key progress contributed to the community, MAS has the advantage of combining rich physics ingredients, realistic global geometry and high computation efficiency together for plasma stability analysis in the linear regime.

We present the kinetic Monte-Carlo model, which was developed to describe the influence of a proton flux from the undisturbed solar wind on the daytime atmosphere of Mars. For the first time, the degradation of the solar-wind proton spectrum in the cascade charge-exchange process in the extended hydrogen corona of Mars has been self-consistently modeled; and the energy fluxes and energy spectra of hydrogen atoms penetrating into the daytime upper atmosphere through the boundary of the induced magnetosphere have been determined. The obtained characteristics make it possible to model numerically the proton auroral phenomena observed in the upper atmosphere of Mars with the Imaging Ultraviolet Spectrometer onboard the Mars Atmosphere and Volatile Evolution spacecraft. In our future studies, we plan to compare the results of these calculations to those of observations, which will provide a unique opportunity to determine more accurately the properties of the atmosphere and the magnetic field of Mars, as well as will improve the techniques for determining the solar wind parameters. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) has become an important research topic in terms of water purification as it is a cost- and energy efficient approach for the desalination of brackish water. Carbon- based materials are often used as electrodes in this process due to a variety of morphologies and their suitable performance in this field. In recent studies it has been already shown that a conscientiously chosen set of electrode properties has an enormous effect on the performance behavior of CDI cells. However, most of the studies focus on the optimization of the electrosorption capacity, while the question on how material properties influence the kinetic behavior of a CDI setup has been less intensively studied so far. Here we show that the kinetic effects of electrode materials can be studied in great detail by using electrochemical impedance spectroscopy (EIS). EIS studies of CDI electrodes have been reported before, however, in contrast to these we introduce a method of presenting and analyzing EIS results. This is especially suitable for extracting the frequency ranges in which different rate limiting mechanisms dominate. The new Nyquist Incline Frequency plot (NIF) shows the local slope of the Nyquist plot in dependency of the applied frequency. By this, electron transfer and mass transfer mechanisms which show a characteristic slope in the classical Nyquist plot can be directly visualized together with the information in which time domain they occur. The data derived from the new EIS plot show a clear correlation to pore size distributions from BET measurements, as well as effective capacities and electrosorption kinetics, extracted from CDI experiments. Therefore, we think that by using the NIF plot electrode materials for CDI processes can be conveniently characterized and compared within a single diagram, helping to standardize CDI material development.

• Calibrations of the TitaniQ thermobarometer are discordant. • Anatase versus rutile affects the crystallization of quartz. • Ti concentrations in hydrothermal quartz grown experimentally (800 °C and 1 kbar) are variable. • A new model can explain the range of Ti variability. • Low- P experiments with slowly grown quartz should be used for thermobarometry of shallow natural systems. We present results from 25 hydrothermal quartz growth experiments, all conducted at 800 °C and 1 kbar but with varying starting materials and run times, to address discrepancies between calibrations of the titanium-in-quartz (TitaniQ) thermobarometer. In our experiments, a gold capsule is loaded with silica glass, water, and either rutile or anatase as the TiO 2 source. In most experiments, there is also a large quartz seed crystal contained in an open inner capsule. The use of rutile versus anatase has a significant influence on the (re)crystallization pathways of the SiO 2 and TiO 2 components. When rutile is used, quartz overgrowths have abundant open cavities and complex zonations. The rutile does not completely dissolve because rutile is the stable TiO 2 polymorph, and yet, new rutile forms at the quartz seed-overgrowth interface and on the outer surface of quartz crystals. This suggests crystallization of quartz near Ω rut ∼ 1, but wide-ranging Ti concentrations and zonations in quartz are indicative of kinetic effects. When powdered anatase is used, the quartz overgrowths look markedly different, lacking the open cavities and instead exhibiting step edges and terraces. The Ti concentrations in quartz from these experiments are also wide-ranging but reach larger values. Our results span the range of previous calibrations and indicate that Ti concentrations in quartz are sensitive to the TiO 2 /SiO 2 ratio of the fluid as opposed to the absolute concentration (or activity) of dissolved TiO 2. We present a kinetic model for quartz and rutile growth from a fluid where the input parameters are the initial degrees of supersaturation with respect to quartz and rutile, the total reactive surface area, and rate constants that link the degree of supersaturation to net precipitation rates. The model can explain many of the salient features of our experimental results, as well as those from previous studies, but requires that the rate constant multiplied by the reactive surface area for rutile is less than that of quartz, and that rutile solubility depends on the SiO 2 concentration of the fluid, as documented in the recent literature. Complete quartz-rutile equilibrium may not have been established in any of the experimental studies, but low-pressure experiments with slowly grown quartz seem to be more reliable than extrapolations from high-pressure experiments for thermobarometry of shallow natural systems. [ABSTRACT FROM AUTHOR]

Kinetic isotope effects (KIEs) during the hydration of carbon dioxide (CO 2) in aqueous solution are key to understanding various geochemical, physicochemical, and biological processes. Despite the growing interest in KIEs in natural systems (e.g., speleothem calcites, skeletal formation of corals, formation of cryogenic carbonates, and more), the currently available experimental data is limited to only a few studies. Here, we report results from laboratory experiments to constrain kinetic isotope fractionation (KIF) during the hydration of CO 2. The experimental setup consisted of a stock solution vessel containing a NaHCO 3 solution, a reaction chamber in which BaCO 3 was rapidly precipitated from a Tris-buffered BaCl 2 solution, and a pump to internally circulate gas throughout the system that was isolated from the ambient laboratory air. Resultant BaCO 3 samples, as well as the NaHCO 3 and deionized H 2 O used for our experiments were analyzed for stable carbon and oxygen isotopes by mass spectrometry. Our experimental results were grouped into four different batches, which were obtained during discrete time periods, while some adjustments to the experimental setup and protocols were implemented to improve the data quality. We discuss possible experimental errors among the four batches and conclude that Batch-4 provided the most reliable results. The average δ13C and δ18O values of the Batch-4 BaCO 3 samples produced at 25 °C and pH NBS = 8.0 are −29.7 ± 0.7‰ (VPDB) and 18.8 ± 0.6‰ (VSMOW), respectively, which is strongly depleted relative to gaseous CO 2 in the system (δ13C VPDB ≅ −10.7‰, δ18O VSMOW ≅ 37.9‰). From the isotope data, we calculate our experimental 13KIF and 18KIF, which refer to the 13C/12C and 18O/16O fractionation between CO 2(g) and BaCO 3 , where the δ13C and δ18O values of CO 2(g) were calculated using known equilibrium fractionation factors. From the mean of Batch-4 results, we conclude 13KIF = 19.6 ± 0.8‰ and 18KIF = 18.8 ± 0.6‰ at 25 °C and pH NBS = 8.0. If full carbon KIF of ∼ 2.0‰ is assumed between CO 2(g) and CO 2(aq) , then the mean 13KIF relative to CO 2(aq) is 17.6 ± 0.8‰. Our KIFs are the largest values compared to previously reported experimental KIFs (except for one study), suggesting that our values are closest to the full isotope disequilibrium during CO 2 hydration, as any partial re-equilibration tends to reduce observed KIFs. [ABSTRACT FROM AUTHOR]

In the present study, we analyze the combined influence of several factors on the rate of atmospheric trace gas adsorption by an ensemble of porous aerosol particles. The factors include the presence of a non-porous non-adsorbing inner core, kinetic effects, non-uniform distribution of concentration of adsorbed gas inside particles, i nert admixtures in the atmosphere, radioactive decay, and particle number density. The particles size has the same order of magnitude as a free path length of molecules in air. The evolution of concentration of adsorbed active trace gas in solid porous particles is described by an integral equation, while the evolution of active trace radioactive gas in a gaseous phase is determined by an integro-differential equation. Numerical calculations are performed to investigate the adsorption of different isotopes of Radon and Iodine by porous particles. The comparison of rates of gas adsorption for radioactive isotopes of Iodine with a stable isotope 1-127 shows that radioactive decay alters the scenario of the gas adsorption process by porous particles. The accuracy of the developed model of radioactive gas adsorption by porous particles is validated by available experimental data. [ABSTRACT FROM AUTHOR]

Sodium and potassium carbonates are important components of high temperature materials. Therefore, information on gas phase is important for modelling of long term processes, where the stability of carbonates should be taken into account. In this study the vaporization behavior of Na 2 CO 3 and K 2 CO 3 has been studied with Knudsen Effusion Mass Spectrometry in the temperature range from 600 to 880 °C. It was established, that vaporization of sodium and potassium carbonates is close to congruent conditions at temperatures below 750 °C with the main species M, CO 2 and O 2 in the gas phase. The vapor pressures of these species are in a good agreement with the calculated values within an error of ± 30%, which are based on the available thermodynamic information including formation enthalpies of M 2 CO 3(s) and M (g) , CO 2(g) and O 2(g) and corresponding thermodynamic functions. At high temperatures above 750 °C incongruent vaporization was observed due to a disproportional increase of the vapor pressure of CO 2. On this stage also Na 2 O+, K 2 O+ and K 2 CO 3 + ions were registered in the mass spectra. Based on the analysis of fragmentation processes of M 2 CO 3 molecules, the sublimation enthalpy ∆ sub H° 298 (K 2 CO 3) is obtained to be 360 kJ/mol. • Vaporization behavior of Na 2 CO 3 and K 2 CO 3 is studied by KEMS. • Congruent vaporization is observed in the temperature range 600–750 °C. • Kinetic effects above 750 °C should be taken into account. • Experimental and calculated data are in good agreement. • Sublimation enthalpy of K 2 CO 3 is reassessed based on the measured data. [ABSTRACT FROM AUTHOR]

The adiabatic temperature change (ATad) in Ni45 Mn43CoSn11 has been measured by a direct method in magnetic field changes up to 14 T. Large reversible magnetocaloric effects resulting in ΔTad of about = -11 and 5 K have been observed for magnetic field changes of 14 T at the magnetostructural (TA ~ 260 K) and magnetic transitions (TC ~ 320 K), respectively. The impact of the thermomagnetic history on ΔTad at high magnetic fields has been reported. The significant observed changes in the relaxation time of ΔTad, depending on the type of the phase transitions, magnetization, and demagnetization cycle are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Observations in kinetic scale field line resonances, or eigenmodes of the geomagnetic field, reveal highly field‐aligned plateaued electron distributions. By combining observations from the Van Allen Probes and Cluster spacecraft with a hybrid kinetic gyrofluid simulation we show how these distributions arise from the nonlocal self‐consistent interaction of electrons with the wavefield. This interaction is manifested as electron trapping in the standing wave potential. The process operates along most of the field line and qualitatively accounts for electron observations near the equatorial plane and at higher latitudes. In conjunction with the highly field‐aligned plateaus, loss cone features are also evident, which result from the action of the upward‐directed wave parallel electric field on the untrapped electron populations. [ABSTRACT FROM AUTHOR]

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We consider the transport of vapour caused by the evaporation of a thin, axisymmetric, partially wetting drop into an inert gas. We take kinetic effects into account through a linear constitutive law that states that the mass flux through the drop surface is proportional to the difference between the vapour concentration in equilibrium and that at the interface. Provided that the vapour concentration is finite, our model leads to a finite mass flux in contrast to the contact-line singularity in the mass flux that is observed in more standard models that neglect kinetic effects. We perform a local analysis near the contact line to investigate the way in which kinetic effects regularize the mass-flux singularity at the contact line. An explicit expression is derived for the mass flux through the free surface of the drop. A matched-asymptotic analysis is used to further investigate the regularization of the mass-flux singularity in the physically relevant regime in which the kinetic timescale is much smaller than the diffusive one. We find that the effect of kinetics is limited to an inner region near the contact line, in which kinetic effects enter at leading order and regularize the mass-flux singularity. The inner problem is solved explicitly using the Wiener-Hopf method and a uniformly valid composite expansion is derived for the mass flux in this asymptotic limit. [ABSTRACT FROM AUTHOR]

We investigate the use of artificially increased ion and electron kinetic scales in global plasma simulations. We argue that as long as the global and ion inertial scales remain well separated, (1) the overall global solution is not strongly sensitive to the value of the ion inertial scale, while (2) the ion inertial scale dynamics will also be similar to the original system, but it occurs at a larger spatial scale, and (3) structures at intermediate scales, such as magnetic islands, grow in a self-similar manner. To investigate the validity and limitations of our scaling hypotheses, we carry out many simulations of a two-dimensional magnetosphere with the magnetohydrodynamics with embedded particle-in-cell (MHD-EPIC) model. The PIC model covers the dayside reconnection site. The simulation results confirm that the hypotheses are true as long as the increased ion inertial length remains less than about 5% of the magnetopause standoff distance. Since the theoretical arguments are general, we expect these results to carry over to three dimensions. The computational cost is reduced by the third and fourth powers of the scaling factor in two- and three-dimensional simulations, respectively, which can be many orders of magnitude. The present results suggest that global simulations that resolve kinetic scales for reconnection are feasible. This is a crucial step for applications to the magnetospheres of Earth, Saturn, and Jupiter and to the solar corona. [ABSTRACT FROM AUTHOR]

We examine in detail δ 18 O and δ 13 C in the calcite internodes of bamboo corals as potential proxies of physiological and environmental variability, through (a) a “core top” calibration that includes specimens from a wide range of habitats and environmental conditions and (b) a comparison of high resolution serial point analyses along radial growth axes of a sub-set of specimens with each other, with instrumental temperature and salinity records, with growth rates and with a nominal skeletal proxy for temperature (Mg/Ca) in the same specimens. At the whole-of-specimen level, δ 18 O and the intercept of the strong within-specimen regression of δ 18 O against δ 13 C correlates highly with ambient temperatures at slopes that are identical to those reported for other marine biogenic carbonates (−0.22 per °C). δ 13 C varies predominantly with apparent specimen-mean growth rate. It also correlates with the slope of the within-specimen covariance between δ 18 O and δ 13 C, which in turn is distributed bi-modally among specimens and linked to differences in apparent growth rates. Within-specimens, variability in δ 13 C, and to a lesser extent δ 18 O, correlates between specimens collected in the same region and differs between regions, implying an environmental effect, but the factors involved for either isotope ratio are unclear. Correlations between δ 18 O and temperature (and Mg/Ca) range from positive to negative among specimens and appear to vary over time even within specimens. The mismatch between the consistent temperature-dependence of δ 18 O at the whole-of-specimen level and the mixed relationship within-specimens can be reconciled by assuming an unknown temperature-dependent factor affecting δ 18 O during the growth of Isidid calcite. The contrast between the results of the “core top” temperature calibration for δ 18 O, which are consistent with studies of other carbonates, and the apparently more complex suite of factors affecting both δ 13 C and δ 18 O within specimens strongly suggests that calibrations based on a “core top” approach be applied cautiously to environmental reconstructions based on variations of a nominal proxy within specimens. [ABSTRACT FROM AUTHOR]

Simulated growth of four global-minimum Lennard-Jones clusters of sizes N = 561, 823, 850 and 923, representing multishell icosahedra and decahedron, always leads to formation of regular polyicosahedral clusters. Observation of cluster structure evolution revealed that new atoms form anti-Mackay islands spreading over the cluster surface by making strong island-island junctions at cluster edges. Analysis of potential energies of atoms composing different local structures shows that energy-driven preference for decahedral arrangement of several atoms initiating the junction of pentagonal symmetry on the cluster surface is responsible for kinetic effect in the cluster growth. [ABSTRACT FROM AUTHOR]

This study presents the carbon, oxygen, and magnesium isotope compositions of two modern brachiopods, Terebratalia transversa and Frieleia halli , and one fossil specimen (2.3 Ma), Terebratula scillae . The aim of this study is to investigate the variability of these isotopic compositions and to evaluate the potential of brachiopods as a proxy of past seawater δ 26 Mg values. The two investigated brachiopod shells present the same range of δ 26 Mg variation (up to 2‰). This variation cannot be ascribed to changes in environmental parameters (temperature or pH). As has been previously observed, the primary layer of calcite shows the largest degree of oxygen and carbon isotope disequilibrium relative to seawater. In contrast, the δ 26 Mg value of the primary layer is comparable to that of the secondary calcite layer value. In both T. scillae and T. transversa , negative trends are observable between magnesium isotopic compositions and oxygen and carbon isotopic compositions. These trends can be explained by kinetic effects linked to changes in growth rate during the brachiopod life. The innermost calcite layer of T. transversa is in isotopic equilibrium for both oxygen and magnesium and could therefore be the best target for reconstructing past δ 26 Mg values of seawater. [ABSTRACT FROM AUTHOR]

A new kinetic model for heating and evaporation of Diesel fuel droplets is suggested. The model is based on the introduction of the kinetic region in the immediate vicinity of the heated and evaporating droplets, where the dynamics of molecules are described in terms of the Boltzmann equations for vapour components and air, and the hydrodynamic region. The effects of finite thermal conductivity and species diffusivity inside the droplets and inelastic collisions in the kinetic region are taken into account. Diesel fuel is approximated by n-dodecane or a mixture of 80% n-dodecane and 20% p-dipropylbenzene. In both cases, the evaporation coefficient is assumed equal to 1. The values of temperature and vapour density at the outer boundary of the kinetic region are inferred from the requirement that both heat flux and mass flux of vapour (or vapour components) in the kinetic and hydrodynamic regions in the vicinity of the interface between these regions should be equal. Initially, the heat and mass fluxes in the hydrodynamic region are calculated based on the values of temperature and vapour density at the surface of the droplet. Then the values of temperature and vapour density at the outer boundary of the kinetic region, obtained following the above-mentioned procedure, are used to calculate the corrected values of hydrodynamic heat and mass fluxes. The latter in their turn lead to new corrected values of temperature and vapour density at the outer boundary of the kinetic region etc. It is shown that this process quickly converges for the cases analysed in the paper, and it leads to self-consistent values for both heat and mass fluxes. The model is applied to the analysis of heating and evaporation of Diesel fuel droplets with initial radii and temperature equal to 5 μm and 300 K, immersed into gas with temperatures in the range 800–1200 K and pressure equal to 30 bar. It is shown that in all cases the kinetic effects lead to a decrease in droplet surface temperature and an increase in the evaporation time. The kinetic effects on the droplet evaporation time are shown to increase with increasing gas temperatures. [ABSTRACT FROM AUTHOR]

Summary We observed stable isotopes in precipitation and atmospheric water vapor over a humid subtropical rice paddy field in Tsukuba, Japan, from June 2013 to May 2014. We used observed isotope ratios, in combination with an isotope-enabled general circulation model (GCM; Isotopes-incorporated Global Spectral Model: IsoGSM) to improve our understanding of the impacts of moisture sources and transport on the variability of water vapor isotopes. The isotopic measurements of water vapor and precipitation suggested that vapor isotopes in the study area were controlled by not only air-rain isotopic exchange, but also other kinetic effects associated with land evapotranspiration and large scale atmospheric circulation at the seasonal time scale. The contribution of land evapotranspiration to local water vapor content ( F ET ) was approximately 16.0 ± 12.3% as an annual average, with a summer maximum of 20.5 ± 12.9%. Our results show that large-scale atmospheric circulation is the primary control on the variability of near surface water vapor δ D . An IsoGSM tagging simulation experiment demonstrated that the large temporal variation of surface water vapor isotopes can primarily be attributed to advection and mixing of moisture from different oceanic source regions. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the environmental controls on the oxygen isotope composition of shells of the European abalone, Haliotis tuberculata . Seasonal δ 18 O profiles from the outer prismatic layer of four abalone shells, collected live in northwest Brittany (France) in 2002 and 2012, were compared to local temperatures and salinities. According to the findings herein, δ 18 O variations in abalone shells corresponded to seasonal variations, and thus, shell composition represented a reliable tool for aging and growth studies. Seawater temperatures estimated from the abalone collected in 2012 reflected the in situ measured temperatures, but the reconstructed temperatures from shells of the three specimens collected in 2002 deviated from measured temperatures by 2.5 °C. This overestimation of temperatures corresponded to a “kinetic effect” related to very high annual abalone growth rates; thus, it could be corrected by applying + 0.53‰ to the δ 18 O shell . This methodology was then applied to a fossil (6000 cal yr BP) collected in the Bay of Biscay. Given the worldwide distribution of both live and fossilized abalones, the results of the present study showed that this genus represents a promising paleoclimatic tool. [ABSTRACT FROM AUTHOR]

It is well known from experimental studies (e.g., Jung et al., 2012, [13]), that solidification of supercooled water occurs in two stages: the initial rapid, recalescent stage of crystallization and the final slower, quasi-isothermal stage. To date, it is not well understood how these stages can be modelled. In the present study it is demonstrated that both freezing stages of supercooled water can be mathematically modelled by utilizing exclusively the minimal (pertinent to the heat-diffusion description) model of solidification: the first unstable stage is physically well described by the dendritic-growth-approach, whereas the second stage of the freezing process is qualitatively and quantitatively defined by a stable planar solidification. The computational model, introduced initially in [7,31], has been appropriately upgraded with respect to the high-fidelity discretization of the thermal-energy equation as well as the normal-to-the-interface temperature gradient determination. At supercooling degrees Δ T higher than ≈5 K (corresponding to high supercooling range), the previously obtained numerical results related to the unstable freezing exhibit a distinct deviation from available experimental data. Possible reasons for this departure can be either the non-consideration of the thermal interaction between the growing needle-like dendrites or neglect of the kinetic effects influencing the growth at such high supercooling conditions. Two-dimensional computations concerning the growth of a needle-like dendrite surrounded by an array of needles indicate that they do not considerably influence the steady-state tip velocity of an isolated needle at higher supercooling. Therefore, the thermal energy equation has been extended through an appropriately derived term mimicking the kinetic undercooling phenomenon. The relevant computational validation results in a very good qualitative and quantitative agreement with experiments in the high-supercooling range as well, illustrating the model's predictive capability of describing both stages of crystallization: the first rapid, dendritic growth (pertinent to unstable freezing) and the second planar growth stage (corresponding to the stable freezing). [ABSTRACT FROM AUTHOR]

We present an ion kinetic model describing the transport of suprathermal α -particles in inertial fusion targets. The analysis of the underlying physical model enables us to develop efficient numerical methods to simulate the creation, transport and collisional relaxation of fusion reaction products ( α -particles) at a kinetic level. The model assumes spherical symmetry in configuration space and axial symmetry in velocity space around the mean flow velocity. A two-energy-scale approach leads to a self-consistent modeling of the coupling between suprathermal α -particles and the thermal bulk of the imploding plasma. This method provides an accurate numerical treatment of energy deposition and transport processes involving suprathermal particles. The numerical tools presented here are then validated against known analytical results. This enables us to investigate the potential role of ion kinetic effects on the physics of ignition and thermonuclear burn in inertial confinement fusion schemes. [ABSTRACT FROM AUTHOR]

The oxygen isotope composition of carbonate minerals varies with temperature as well as other environmental variables. For carbonates that precipitate slowly, under conditions that approach thermodynamic equilibrium, the temperature-dependence of 18 O uptake is the dominant signal and the measured 18 O content can be used as a paleotemperature proxy. In the more common case where carbonate minerals grow in a regime where they are not in isotopic equilibrium with their host solution, their oxygen isotope compositions are a convolution of multiple environmental variables. Here we present results from calcite growth experiments demonstrating the occurrence of large ( > 2 ‰ ) non-equilibrium oxygen isotope effects under conditions relevant to biogenic calcite growth and many natural inorganic systems. We show that these non-equilibrium effects vary systematically with pH and crystal growth rate. An isotopic ion-by-ion crystal growth model quantifies the competing roles of temperature, pH, and growth rate, and provides a general description of calcite–water oxygen isotope fractionation under non-equilibrium conditions. The crystal growth model results show that (1) there are both equilibrium and kinetic contributions to calcite oxygen isotopes at biogenic growth rates, (2) calcite does not directly inherit the oxygen isotope composition of DIC even at fast growth rates, (3) there is a kinetically controlled variation of about 1‰ per pH unit between pH = 7.7 and 9.3 at constant growth rate for inorganic calcite as well as biogenic calcite, and (4) extreme light isotope enrichments in calcite in alkaline environments are likely due to disequilibrium among DIC species in aqueous solution. The model can be extended to 13 C uptake into carbonates as well as clumped isotopes but additional data are needed to constrain the kinetic fractionation factors for carbon isotopes. The experimental and model results constitute an important step in separating the relative influence of inorganic and biologic processes on isotopic fractionation and may aid the development of new paleoproxies based on non-equilibrium effects. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we investigate the entropy change and the kinetics at the magneto-structural transition (at 628 K) of polycrystalline MnBi. Samples were prepared by rapid quenching and annealing and exhibit 86 wt% of the hexagonal MnBi phase. The entropy change at the transition is found to be Δs = 17.6 J kg−1 K−1 and the magnetic field shifts the transition temperature at a rate of 2.6 K T−1. The temperature hysteresis, of 19 K, is quite large for magneto-thermal application. The transition shows kinetics effects upon cooling in which the transition temperature is found to depend approximately to the logarithm of the temperature rate with coefficient −3.8 K. [Copyright &y& Elsevier]