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The shard of glass in the river today couldn't cut anything, and these wooden shelves don't remember the breeze of their last hillside. Our dog is on the mantel now. [...]

The surface intermediates formed on the Mg-La catalyst (molar ratio 1:1) were studied through temperature-programmed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy coupled to mass spectrometry (DRIFTS-MS) using methanol (MeOH) and ethyl acetate (EA) as probe molecules. TPD results showed that the products formed from adsorbed MeOH were hydrogen and formaldehyde, whereas EA produced hydrogen, ethanol, and acetone. DRIFTS-MS of a MeOH and EA mixture results showed that methanol adsorbs as methoxy species on the catalyst surface, and EA adsorbs through the oxygen of carbonyl groups forming ethoxy and acetate species. The reaction of the adsorbed intermediate species resulted in the formation of methane, CO2 gas phase, ethanol, and methyl acetate. Also, methanol adsorbed preferentially on the basic site and EA in a dissociative form. Surface intermediates identification allowed to confirm that the Eley-Rideal type mechanism was predominant on the catalyst surface studied.

Abstract We present the results of an effort to model quiet-time vertical plasma drifts in the low-latitude F-region ionosphere using the random forest machine learning technique. The model is capable of describing the climatological variation of the drifts as a function of universal time, day of the year, solar flux, and altitude (200–600 km). The model has been trained using measurements of the vertical plasma drifts made by the incoherent scatter radar of the Jicamarca Radio Observatory ( $$11.95^\circ \hbox { S}$$ 11 . 95 ∘ S , $$76.87^\circ$$ 76 . 87 ∘ W, $$\sim 1^\circ$$ ∼ 1 ∘ dip lat). In our analysis, we compare our machine learning model results with the Scherliess and Fejer (J Geophys Res 104:6829–6842, 1999) model (SF99 model), a widely used empirical model of the vertical drifts developed using a different set of Jicamarca measurements. We find that the machine learning model is able to capture the overall features of the diurnal variation of the equatorial drifts for different seasonal and solar flux conditions. The model is also capable of capturing the mean height variation of the drifts, particularly the height gradient enhancements that have been observed near sunrise and sunset. Finally, the model can easily be expanded and improved as more drift measurements are made and become available for training.

Drifts affect particle, momentum, and energy transport in the scrape-off layer (SOL) of tokamaks and stellarators, altering plasma flows and creating asymmetries between divertors. To understand how drifts affect SOL transport in the W7-X island divertor, an experiment was performed to compare plasmas with matched core parameters but opposite magnetic field directions, and therefore opposite drift transport directions. Parallel flow measurements made with coherence imaging spectroscopy are interpreted with the aid of a diagnostic forward model and a 1D simple SOL model that includes the $\boldsymbol{\mathbf{E}} \times \boldsymbol{\mathbf{B}}$ drift. In low-density plasmas ( $\overline{n}_\mathrm{e} \lt 2 \times 10^{19}$ m ^−3 ), the poloidal $\boldsymbol{\mathbf{E}} \times \boldsymbol{\mathbf{B}}$ drift induces a large poloidal density asymmetry within the island SOL, as measured by divertor Langmuir probes. This in turn causes the parallel flow stagnation point to shift from the position halfway between targets to the X-point in the drift direction, leading to near-unidirectional flow throughout the SOL. As density increases, the effects of the poloidal $\boldsymbol{\mathbf{E}} \times \boldsymbol{\mathbf{B}}$ drift decrease substantially, resulting in a smaller density asymmetry and the development of a counter-streaming flow pattern. For the entire density range probed in this experiment ( $\overline{n}_\mathrm{e} = 1.5-6\times 10^{19}$ m ^−3 ), the experimental observations are more consistent with the effects of the poloidal $\boldsymbol{\mathbf{E}} \times \boldsymbol{\mathbf{B}}$ drift than the radial $\boldsymbol{\mathbf{E}} \times \boldsymbol{\mathbf{B}}$ drift.

Abstract We have identified over 200 fast plasma drift events (>5 km/s) in the high‐latitude ionosphere, as measured by the electric field double probe on the Dynamics Explorer‐2 satellite during its 18 months lifetime from August 1981 to February 1983. Although these drifts can appear at all local time sectors, they are most common on the dawnside and in the pre‐midnight sector. The fast plasma drifts generally occur between 64° and 82° inv.lat. although they sometimes appear below 55° inv.lat. in the pre‐midnight sector, in which case they appear associated with a phenomenon often referred to as sub‐auroral ion drifts. For increasing Auroral Electrojet index, their occurrence rate increases and their latitudinal locations move equatorward. The observed events last between 0.1 and 60 s, corresponding to (north‐south) widths of 1–500 km along the satellite trajectory. The observations show a seasonal dependence such that the faster drifts tend to occur over the dark (winter) hemisphere.

A new drift module has been developed in the DIVIMP code, enabling two-dimensional simulations of tungsten (W) transport in the edge plasma with full drifts included. By using the SOLPS-DIVIMP code package, the impact of drifts on W transport and screening has been investigated for various levels of dissipative divertor conditions and different divertor geometric configurations in EAST. Simulation results reveal that $\vec E \times \vec B$ drifts can enhance the W leakage by more than one order of magnitude. Under the favorable B _t direction, W erosion mainly occurs on the outer divertor target, making the W leakage from the outer divertor region the dominator. A leakage path from the near-scrape-off layer (SOL) region is revealed by the modeling results. In the leakage path, both the ion temperature gradient force and the reversed poloidal $\vec E \times \vec B$ drift are pointing upstream. With the radial $\vec E \times \vec B$ drift pushing W ions from the well-screened far-SOL region to the near-SOL region, the leakage from the near-SOL region becomes significant. As the divertor condition varies from the low-recycling regime to the deep detachment regime, the decrease of the ion temperature gradient velocity and poloidal $\vec E \times \vec B$ drift velocity narrows the width of the near-SOL leakage tunnel and thus enhances W screening. While under the unfavorable B _t , W erosion and leakage from the inner divertor target matters, the leakage mechanism especially the leakage path from the near-SOL region is similar as the favorable B _t cases. Furthermore, the effect of different divertor geometries on the W screening has been investigated. The configuration with the outer strike point (OSP) on the horizontal divertor plate is proved to narrow the near-SOL leakage tunnel, and thus the unreversed poloidal $\vec E \times \vec B$ drift pointing to the divertor target dominates and helps to enhance the divertor W screening. For the same D _2 puffing rate, the W leakage ability of cases with the OSP on the horizontal target can be more than 10 times weaker than the cases with the OSP on the vertical target, especially when the divertor is detached.

Successful fusion reactor operation relies on minimal core contamination by impurities, otherwise too much power may be radiated and harm performance. This requires reliable predictions of impurity transport from the scrape-off layer (SOL) into the core, beyond the traditional ‘anomalous’ diffusion approach. We report a set of far-SOL tungsten transport simulations that demonstrate the role of turbulent drifts on radial impurity transport. A turbulent plasma background is simulated using the gyrokinetic SOL code Gkeyll. Tungsten ions are followed within the plasma background using only their drifts. We find that tungsten tends to travel radially outwards with velocities between v _r = 300–1200 m s ^−1 primarily due to polarization drift. We also extract an anomalous radial diffusion coefficient that varies from $D_{\text{r}}^{{\text{anom}}}$ = 5–20 m ^2 s ^−1 . These results are compared to and agree with previous interpretive modeling results. We also show how the turbulent polarization drift can transport some tungsten ions from the wall inwards with effective pinch velocities up to 10 000 m s ^−1 . We conclude that turbulent drifts are a likely explanation for historically anomalous radial impurity transport.

The effect of drifts combined with pumping on particle exhaust is assessed using the SOLPS-ITER code package, considering full drifts. Both drift and pumping speed S can affect particle exhaust. Drifts change the neutral density by influencing plasma flow and the resulting particle recycling. This leads to the accumulation of neutral particles either far away or close to the pump opening location. The particle exhaust is enhanced as S rises. When the pump opening is positioned at the common flux region (CFR) of the outer divertor (referred to as Pump CFR/OD), particle exhaust is suppressed by drifts in forward B _t , while it is enhanced by drifts in reversed B _t , with fixed S . On the other hand, when the pump is situated in the private flux region (PFR) of the OD (referred to as Pump PFR/OD), particle exhaust is enhanced by drifts in both reversed and forward B _t compared to the case without drifts. Moreover, the effective pumping in reversed B _t is stronger than in forward B _t . In the same B _t direction, Pump PFR/OD has a higher effective pumping than Pump CFR/OD. Increased S results in higher particle exhaust in all B _t direction and pump location cases. The plasma detachment is affected by drift, S and pump opening location, respectively. For the specified B _t direction and pump opening location case, higher S suppresses plasma detachment. For identical particle exhaust rates, stronger pumping capacity can promote plasma detachment. Therefore, Pump PFR/OD can more easily achieve OD detachment than Pump CFR/OD in the same B _t direction. Overall, placing the pump at the PFR side of the OD while running in reversed B _t is the best option from the divertor particle exhaust and plasma detachment point of view.

The heat flux width ( λ _q ) is a key parameter determining the heat load at divertor targets. In recent years, drifts have been found to play a remarkable role in the edge plasma transport, while its influence on λ _q has not been well understood. Investigations of the influence of drifts on λ _q , systematic simulations using the SOLPS-ITER code are performed in this work. The statistics of the simulation results show that the drift under favorable/unfavorable B _T tends to increase the λ _q in the outer/inner side and decrease the λ _q in the other side, which is consistent with the experiment observations. At the upstream and the target, the mechanisms of the influence of the drifts on λ _q are different. The upstream λ _q ( λ _q _,u ) is directly affected by the drift-induced convective heat flux, while λ _q at the target ( λ _q _,t ) is indirectly influenced through heat conduction (in the high-recycling regime) and the sheath (in the detached regime) due to the change of plasma parameters there. Furthermore, the synergetic effect of geometry and drift under favorable B _T leads to an anomalously large λ _q _,t in the inner side at high density.

In this study, we utilize ICON observations from 2019 to 2022 to analyze the variability of vertical plasma drift and its relationship with the neutral winds. The results reveal that there are 19% of downward plasma drifts at 13–17 LT, which changes with seasons and longitudes. The downward plasma drift occurs less frequently compared to the contemporaneous counter electrojet during solstices. We identify the relationship between vertical plasma drifts and north foot magnetic zonal and meridional wind profiles at 90–300 km altitudes. As the vertical plasma drifts become small or downward, the zonal winds display diverse variations at the altitudes; that is, the disturbances are eastward at 95–120 km altitudes, westward at 120–160 km altitudes, and eastward above 180 km altitudes, while the meridional winds present weak changes in all altitudes. Additionally, we discuss the possible roles of the E‐ and F‐region dynamos on the vertical plasma drifts. Plain Language Summary: The neutral wind in the Earth's upper atmosphere drives the ionospheric ions to cross the geomagnetic field lines and produces the dynamo effects in the E‐ and F‐regions. The electric field is created due to the divergence free of the total electrical current. The zonal electric field drives the ionospheric plasma to drift upward and downward due to the horizontal field lines, and influences the structures of low latitude ionosphere. One open question is that the vertical plasma drift shows the significant day‐to‐day variability and sometimes remarkably deviates from the climatological pattern during the quiet times. The ICON satellite provides the simultaneous observations of the plasma drifts and neutral winds in low latitudes, which provides us a good chance to investigate the day‐to‐day variability of the vertical plasma drift and its relationship to the neutral wind, as we discuss in the manuscript. Key Points: The equatorial vertical plasma drifts show large variability and 19% downward plasma drift at 13–17 LTThe occurrence of the downward plasma drift presents a significant longitudinal and seasonal variationsThe E‐ and F‐region zonal winds play vital roles on the large variability and the occurrence of the downward plasma drift [ABSTRACT FROM AUTHOR]

The transport properties of gapless edge modes at boundaries between topologically distinct domains are of fundamental and technological importance. We experimentally studied long-distance quantized Hall drifts in a harmonically confined topological pump of ultracold fermionic atoms. We found that quantized drifts halt and reverse their direction when the atoms reach a critical slope of the confining potential, revealing the presence of a topological boundary. The drift reversal corresponded to a band transfer between a band with Chern number C = +1 and another with C = -1 through a gapless edge mode, in agreement with the bulk-edge correspondence for noninteracting particles. Nonzero repulsive Hubbard interactions led to the emergence of an additional edge in the system through a mechanism in which pairs of fermions are split. [ABSTRACT FROM AUTHOR]

The inclusion of drifts in plasma edge codes like SOLPS-ITER is required to match simulation data with experimental profiles. However, this remains numerically challenging. In this paper, the effect of some numerical factors on the final plasma solution is investigated. This study is performed on three EAST simulations in the upper single null configuration: an attached purely deuterium case, an attached case with limited Ne-seeding, and a detached Ne-seeded case. The effects of the anomalous conductivity and anomalous thermo-electric coefficient on the plasma potential are investigated. Next, the effect of the employed grids is shown. In order to investigate these effects, accurate drift simulations are needed. Therefore, the employed time step and numerical parameters are discussed for the three studied simulations. For all presented simulations, it is verified that the restriction of the grid to the first flux surface tangent to the main chamber wall is sufficient within the context of non-extended simulations. This means that the main power dissipation takes place inside the simulated domain, and only a small fraction of the power is leaving the B2.5 grid through the grid boundary closest to the first wall. Finally, the effect of drifts on the asymmetry between the inner and outer target for EAST simulations is demonstrated. [ABSTRACT FROM AUTHOR]

The paper presents comprehensive studies of abutment pressure formation zones in the geotechnical system of "paired drifts", including numerical simulation based on the finite element method. For the simulation, the Mohr - Coulomb elastic-plastic model was used, as well as physico-mechanical properties of coal and host rocks. The simulation was carried out for specific mining and geological conditions of k2 anthracite seam occurrence. In a software module, several stages were simulated, allowing to determine magnitude of stresses and displacements of the roof in stopes at various stages of abutment pressure formation in front of the advancing stoping face. As a result of the simulation, the values of the stresses and displacements of the roof in the rock mass around the stopes at various stages of the development of the abutment pressure formation zones were obtained, enabling using the experimental design method to optimize the parameters of adjustable pillar (as support structure). These studies are aimed at improving efficiency of stope protection by optimizing the parameters of protective support structures (adjustable pillars) to increase productivity of the stoping face during excavation of flat-lying anthracite seams, including rockburst-dangerous ones.

An instrumental drift in the point target response (PTR) parameters has been detected on the Copernicus Sentinel-3A altimetry mission. It will affect the accuracy of sea level sensing, which could result in errors in sea level change estimates of a few tenths of a millimeter per year. In order to accurately evaluate this drift, a method for detecting global and regional mean sea level relative drifts between two altimetry missions is implemented. Associated uncertainties are also accurately calculated thanks to a detailed error budget analysis. A drift on both Sentinel-3A (S3A) and Sentinel-3B (S3B) global mean sea level (GMSL) is detected with values significantly higher than expected. For S3A, the relative GMSL drift detected is 1.0 mm yr−1 with Jason-3 and 1.3 mm yr−1 with SARAL/AltiKa. For S3B, the relative GMSL drift detected is −3.4 mm yr−1 with Jason-3 and −2.2 mm yr−1 with SARAL/AltiKa. The drift detected at global level does not show detectable regional variations above the uncertainty level of the proposed method. The investigations led by the altimeter experts can now explain the origin of this drift for S3A and S3B. The ability of the implemented method to detect a sea level drift with respect to the length of the common period is also analyzed. We find that the minimum detectable sea level drift over a 5-year period is 0.3 mm yr−1 at the global scale and 1.5 mm yr−1 at the 2400 km regional scale. However, these levels of uncertainty do not meet the sea level stability requirements for climate change studies.

The ambipolar diffusion approximation is used to model partially ionized plasma dynamics in a single-fluid setting. To correctly apply the commonly used version of ambipolar diffusion, a set of criteria should be satisfied including the requirement that the difference in velocity between charges and neutral species (known as drift velocity) is much smaller than the thermal velocity, otherwise the drift velocity will drive a non-negligible level of further collisions between the two species. In this paper, we explore the consequences of relaxing this assumption. We show that a new induction equation can be formulated without this assumption. This formulation reduces to the ambipolar induction equation in the case the drift velocity is small. In the large drift velocity limit, the feedback of the drift velocity on the collision frequency results in decreased diffusion of the magnetic field compared with the standard ambipolar diffusion approximation for the same parameters. This has a natural consequence of reducing the frictional heating that can occur. Applying this to results from flux emergence simulations where the expansion of the magnetic field leads to strong adiabatic cooling of the partially ionized chromosphere resulted in a noticeable reduction in the magnitude of the predicted drift velocities. This article is part of the theme issue 'Partially ionized plasma of the solar atmosphere: recent advances and future pathways'. [ABSTRACT FROM AUTHOR]

Layered double hydroxide (LDH) nanostructures are commonly used to study the interfacial effects of Pt‐based catalysts in CO oxidation. However, the specific role and detailed intermediates involved in CO oxidation remain unclear. Density functional theory (DFT) predicted that NiFe LDH loaded with single Pt atoms would exhibit satisfactory CO oxidation activity. On this basis, we prepared Pt1NiFe LDH catalysts with various Fe : Ni ratios by using the one‐pot method and achieved favorable dispersion of single Pt atoms. Pt1/FN‐1, which had the optimal Fe : Ni ratio (1 : 1), exhibited satisfactory catalytic performance for CO oxidation and a high turnover frequency, as determined through DFT calculations and experimental characterization. In‐situ diffuse reflectance infrared Fourier transform spectroscopy confirmed that CO directly reacted with Pt1/FN‐1 to produce CO2 and that introduced O2 formed bicarbonate species to produce CO2 together with the adsorbed CO on Pt1 sites. Overall, our work provides new insights into the catalytic mechanism of the well‐known Pt1NiFe LDH catalysts in CO oxidation. [ABSTRACT FROM AUTHOR]

Consider the motion of a Brownian particle in n dimensions, whose coordinate processes are standard Brownian motions with zero drift initially, and then at some random/unobservable time, exactly k of the coordinate processes get a (known) nonzero drift permanently. Given that the position of the Brownian particle is being observed in real time, the problem is to detect the time at which the k coordinate processes get the drift as accurately as possible. We solve this problem in the most uncertain scenario when the random/unobservable time is (i) exponentially distributed and (ii) independent from the initial motion without drift. The solution is expressed in terms of a stopping time that minimizes the probability of a false early detection and the expected delay of a missed late detection. The elliptic case k = 1 has been settled in [4] where the hypoelliptic case 1< k

Climate change mitigation (CCM) has not been mainly understood and assessed in the terms of carbon drifts persisting at provincial level of China, and to respond the question that how green financing is better financing option for CCM. Thus, our study intends to test the role of green finance on carbon drifts to manage for the mitigation of climate change. For this, unit root test and panel co-integration technique is applied. Study findings reported that the intricate connection between place-and-time-specific GHG emission reduction responsibilities is significant with 18% and the ‘production’, trading and consumption of carbon allowances with 21% and offsets across vast time-space stretches related carbon drift is significant with 19.5% for climate change mitigation. For such significance, green financing is found imperative indicators which is significant at 27.1% with carbon drifts, and mitigates the climate change with 31.3%, which is, relatively high than usual climate change control practices. Our study also provides detailed policy implication on this topicality for associated stakeholder.

Abstract Machine learning models are widely applied to predict molecular properties or the biological activity of small molecules on a specific protein. Models can be integrated in a conformal prediction (CP) framework which adds a calibration step to estimate the confidence of the predictions. CP models present the advantage of ensuring a predefined error rate under the assumption that test and calibration set are exchangeable. In cases where the test data have drifted away from the descriptor space of the training data, or where assay setups have changed, this assumption might not be fulfilled and the models are not guaranteed to be valid. In this study, the performance of internally valid CP models when applied to either newer time-split data or to external data was evaluated. In detail, temporal data drifts were analysed based on twelve datasets from the ChEMBL database. In addition, discrepancies between models trained on publicly-available data and applied to proprietary data for the liver toxicity and MNT in vivo endpoints were investigated. In most cases, a drastic decrease in the validity of the models was observed when applied to the time-split or external (holdout) test sets. To overcome the decrease in model validity, a strategy for updating the calibration set with data more similar to the holdout set was investigated. Updating the calibration set generally improved the validity, restoring it completely to its expected value in many cases. The restored validity is the first requisite for applying the CP models with confidence. However, the increased validity comes at the cost of a decrease in model efficiency, as more predictions are identified as inconclusive. This study presents a strategy to recalibrate CP models to mitigate the effects of data drifts. Updating the calibration sets without having to retrain the model has proven to be a useful approach to restore the validity of most models.

Catalytic ozonation, with enhanced efficiency and reduced byproduct formation at lower temperatures, proved to be efficient in ethyl acetate (EA) degradation. In this work, MMn2O4 (M = Cu, Co, Ni, Mg) catalysts were prepared via a redox-precipitation method to explore the catalytic ozonation mechanism of EA. Among all the catalysts, CuMn exhibited superior catalytic activity at 120 °C, achieving nearly 100% EA conversion and above 90% CO2 selectivity with an O3/EA molar ratio of 10. Many characterizations were conducted, such as SEM, BET and XPS, for revealing the properties of the catalysts. Plentiful active sites, abundant oxygen vacancies, more acid sites and higher reduction ability contributed to the excellent performance of CuMn. Moreover, the addition of NO induced a degree of inhibition to EA conversion due to its competition for ozone. H2O had little effect on the catalytic ozonation of CuMn, as the conversion of EA could reach a stable platform at ~89% even with 5.0 vol.% of H2O. The presence of SO2 usually caused catalyst deactivation. However, the conversion could gradually recover once SO2 was discontinued due to the reactivation of ozone. A detailed reaction mechanism for catalytic ozonation was proposed via in situ DRIFTS measurements and DFT calculations.