eV Energy Research Articles

Effect of cage bias and electron emission on the two-electron temperature groups in a hot cathode discharge

In the target multi-pole magnetic cage of the double plasma device, where the plasma diffuses through the magnetic filter after its production in the source region, the effect of the cage biasing, introduction of auxiliary filament and accelerating voltage on the control of the temperature and density of the two-electron groups in a hydrogen bi-Maxwellian plasma is carried out. This control of the electron groups in turn will help to enhance the negative ion density. In the absence of biasing voltage, the density of low-energy electrons and high-energy electrons were of the orders ∼1014 m−3 and ∼1012 m−3 respectively. As the cage is biased negatively, these values increased to an order of ∼1016 m−3 and ∼1013 m−3 respectively. With negative cage biasing, the temperature of the high energy electrons was ∼5 eV and low energy electrons ∼0.6 eV. The introduction of an auxiliary electron source in the target region together with the application of an accelerating voltage along with biasing voltage further increased the density of low-energy electrons to ∼4 × 1016 m−3.

Efficient immobilization and detoxification of gaseous elemental mercury by nanoflower/rod WSe2/halloysite composite: Performance and mechanisms

Gaseous mercury pollution control technologies with low stability and high releasing risks always face with great challenges. Herein, we developed one halloysite nanotubes (HNTs)-supported tungsten diselenide (WSe2) composite (WSe2/HNTs) by one-pot solvothermal approach, curing Hg0 from complicated flue gas (CFG) and reducing second environment risks. WSe2 as a monolayer with nano-flower structure and HNTs with rod shapes in the as-prepared sorbent exhibited outstanding synergy efficiency, resulting in exceptional performance for Hg0 removal with high capture capacity of 30.6 mg·g−1 and rate of 9.09 μg·g−1·min−1, which benefited from the high affinity of selenium and mercury (1 ×1045) and the adequate exposure of Se-terminated. The adsorbent showed beneficial tolerance to high amount of NOx and SOx. An online lab-built thermal decomposition system (TPD-AFS) was employed to explore Hg species on the used-sorbent, finding that the adsorbed-mercury species were principally mercury selenide (HgSe). Density functional theory calculations indicated that the hollow-sites were the major adsorption sites and exhibited excellent selectivity for Hg0, as well as HgSe generation needed to overcome the 0.32 eV energy barrier. The adsorbed mercury displayed high environmental stability after the leaching toxicity test, which significantly decreased its secondary environmental risks. With these advantages, WSe2/HNTs possess enormous potential to achieve the effective and permanent immobilization of gaseous mercury from CFG in the future.

Effect of Ruthenium Modification of g-C3N4 in the Visible-Light-Driven Photocatalytic Reduction of Cr(VI)

Graphitic carbon nitride (g-C3N4) is a promising heterogeneous photocatalyst in the visible range. It can be used, among others, for reductive conversion of the toxic hexavalent chromium occurring in various wastewaters. Its photocatalytic efficiency, however, has to be improved, which can be realized by modification with different dopants or co-catalysts forming heterojunctions. In our work, ruthenium-modified g-C3N4 has been prepared by ultrasonic impregnation of the pristine g-C3N4, which was synthesized from thiourea. The morphology, microstructure, and optical properties of the photocatalysts were characterized by XRD, SEM, FT-IR, TEM, XPS, and DRS. Their compositions were analyzed by EDS and XPS measurements, indicating 0.5% and 1.4% Ru, due to the different penetrating depths. XPS study showed mainly +2 for the oxidation state of Ru. DRS analysis indicated a slight change in both the CB (from −1.14 to −1.22 eV) and the VB (from 1.49 to 1.56 eV) energies of Ru/g-C3N4, compared to those of g-C3N4. The photocatalytic Cr(VI) reduction efficacy increased from 50.1 to 96.8%. Low pH (=2) was preferred for the photocatalytic Cr(VI) reduction due to the favorable surface charge and E(Cr(VI)/Cr(III)) redox potential. Ru modification proved to be promising for improving the photocatalytic performance of g-C3N4.

Impact of M atomic species on physical properties of M2TlC (M = Ti, Zr, Hf): A first principles calculation

We characterize the physical feature of M2TlC (M = Ti, Zr, and Hf) MAX phase ternary carbides applying density functional theory. Along with previously calculated structural, elastic, and electrical properties, Vickers hardness, dynamical stability, and optical feature of the phases are also calculated. The Pugh ratio and Poisson’s ratio show the compounds’ brittleness in conjunction with their potent directional covalent bonds and combination of ionic contributions. The metallic character of the phases is supported by the Fermi level overlap of the conduction band and valence band. The examined materials have moderate hardness, according to the Vickers hardness, with the Hf2TlC combination having the highest value of 2.60 GPa. A number of well-known phenomena are used to compute and thoroughly analyze the optical characteristics. Notably, all investigated compounds show reflectivity above 44% up to 12.0 eV energy, which is encompassed by the infrared and visible regions. The compounds could therefore be used, in practice, as a coating material to lessen solar heating.

Investigation on ethylene glycol and glycerol mixture concentration dependent optical, dielectric, electrical, rheological, and thermophysical properties of EG+Gly/ZnO semiconductor nanofluids

Wide energy bandgap metal oxide nanomaterials containing semiconductor nanofluids (SNFs) are technologically established as advanced multifunctional materials for progress in high performance soft condensed devices. Therefore, to strengthen this field of materials, the present study reports in detail the optical, dielectric, electrical, rheological, and thermophysical properties of the SNFs based on ethylene glycol (EG) and glycerol (Gly) mixture of an entire concentration range (Gly volume fractions; 0.00, 0.25, 0.50, 0.75, and 1.00) with a fixed amount of zinc oxide (ZnO) semiconductor nanomaterial (0.05 wt%). These green-formulated EG + Gly/ZnO SNF materials showed a longer stability of the suspended nanoparticles in the highly viscous hydrogen bonded base fluid and exhibited an increase in absorbance with the decrease wavelength of visible range photons and the ZnO electronic transition at about 3.2 eV energy of ultraviolet radiations. Dielectric measurements over the 20 Hz–1 MHz range of these SNFs, at 298.15 K, explained a dominant contribution of the electrode and interfacial polarization processes at low frequencies and the molecular dipole polarization of static permittivity about 40 at the higher frequencies. Electrode polarization and conductivity relaxation times enhanced exponentially when the Gly concentration increased in the EG + Gly base fluid which governs the electrical conductivity decrement from 0.79 to 0.04 μS/cm for these SNFs. The rheological study explained the Newtonian characteristics of EG + Gly/ZnO nanofluids with their base fluid mixture concentration controllable dynamic viscosity in the wide range of 17–702 mPa s, at 298.15 K. The density, refractive index, ultrasound velocity, prominent acoustic parameters, and thermal conductivity are determined and discussed to explore the solid-liquid interaction and interfaces formed in these innovative SNF materials.

0D/1D CuFeO2/CuO nanowire heterojunction arrays for improved photoelectrocatalytic reduction of CO2 to ethanol

CuO material with a bandgap of 1.2–1.9 eV and suitable energy level is a promissing material for photoelectrocatalytic reduction of CO2. However, the serious photocorrosion limits its performance improvement. Herein, an in-situ synthesis route is designed to fabricate 0D/1D CuFeO2/CuO nanowire heterojunction arrays with large specific surface. The nanowire heterojunction arrays presented excellent activity for photoelectrochemical reduction of CO2 to ethanol with an optimal faradaic efficiency of 66.73% at - 0.6 V (vs. Ag/AgCl). A heterojunction is formed between CuFeO2 and CuO, and the enhanced charge transfer mechanism is proposed based on the measurement of energy band structures. Under the action of interfacial built-in electric field of heterojunction, photogenerated holes are transferred from the valence band of CuO to CuFeO2, and photogenerated electrons are transferred from the conduction band of CuFeO2 to CuO with high selective reduction of CO2 to ethanol.

Development of strain compensated InGaAs/InGaP multiple quantum wells in the 1.05–1.50 eV energy range for multijunction solar cells

In this work, we investigate the influence of structure parameters of strain compensated InGaAs/InGaP multiple quantum wells on the optical and mechanical properties of the system. With theoretical simulations, we show that this system is suitable to operate within the entire 1.05–1.50 eV range without surpassing the critical layer thicknesses. Therefore, we propose its use as the active region of intermediate junctions in multijunction solar cells for specific applications. Furthermore, we present experimental results demonstrating the tunability of the transition energy of this system from 1.28 to 1.40 eV. In order to reach the bottommost part of this range (1.35–1.28 eV) though, GaAs interlayers between the barriers and the quantum wells are required. We show that the introduction of interlayers serves both to tailor the strain between the layers and block the interdiffusion of As/P at the heterointerface.

Investigation of phosphorus-doping of MgZnO thin films using efficient spin-on dopant process

Phosphorus doped MgZnO thin films were prepared using the RF sputtering technique on a Si wafer, followed by spin-on doping (SOD) and annealing. The SOD is a cheap and non-destructive process in which the dopant film is spun on a Si wafer and placed in the vicinity of deposited undoped MgZnO thin film at a high temperature to perform doping. After doping, the MgZnO thin films were annealed at temperatures such as 700, 800, and 900 °C, which significantly improved morphological, structural, and optical properties. The atomic force microscopy and scanning electron microscopy measurements revealed that phosphorus-doped MgZnO thin films annealed at 800–900 °C have good morphology and large grains. X-ray diffraction spectra demonstrated the (002) orientation of MgZnO thin films. The photoluminescence spectra measured at 20 K demonstrated the acceptor bound exciton peak at 3.47 eV and acceptor binding energy of around 64.34 meV, indicating the formation of shallow acceptor levels by phosphorus doping of MgZnO thin films using the SOD process. In Raman spectroscopy measurement, the peak of E2high phonons mode of MgZnO wurtzite structure was observed around 436 cm−1. The FWHM value of this peak reduces with augmentation annealing temperature, demonstrating improvement in crystallinity. X-ray photoelectron spectroscopy measurement demonstrated the presence of phosphorus atoms in the SOD processed MgZnO thin films, which is again verified by Fourier-transform infrared spectroscopy measurement showing vibration modes of P–O bonds. It was observed that the different properties of SOD-prepared phosphorus-doped MgZnO films were superior to the film prepared using the alternate costly and destructive ion-implantation technique. These findings have revealed that high-quality phosphorus-doped p-type MgZnO thin films by the SOD process are very suitable for UV optoelectronic device applications.

Synthesis of highly superhydrophilic [formula omitted] film using dip coating method

In the present work, Copper Oxide (Cu2O) film is fabricated on a glass using mixing solution of sodium thiosulfate and copper sulfate by dip coating method. After some modification super hydrophilic Cu2O film was obtained. The prepared film shows outstanding water absorbance with very less contact angle. XRD shows mixed phase of Cu2O and CuO. The UV–VIS spectroscopy of film shows absorption peak at 575 nm which corresponds to 2.56 eV energy band gap which is calculated from tauc’s plot. SEM analysis shows that the surface morphology of deposited Cu2O film on glass slide shows grain of irregular shape. The EDX spectrum of obtained Cu2O shows elemental composition of 61.58% of Cu and 38.42% of O. FTIR provides information about materials phase composition. Results show that all copper oxide surfaces tends to hydrophilic behavior after drying at ambient condition.

Imaging of Antiferroelectric Dark Modes in an Inverted Plasmonic Lattice.

Plasmonic lattice nanostructures are of technological interest because of their capacity to manipulate light below the diffraction limit. Here, we present a detailed study of dark and bright modes in the visible and near-infrared energy regime of an inverted plasmonic honeycomb lattice by a combination of Au+ focused ion beam lithography with nanometric resolution, optical and electron spectroscopy, and finite-difference time-domain simulations. The lattice consists of slits carved in a gold thin film, exhibiting hotspots and a set of bright and dark modes. We proposed that some of the dark modes detected by electron energy-loss spectroscopy are caused by antiferroelectric arrangements of the slit polarizations with two times the size of the hexagonal unit cell. The plasmonic resonances take place within the 0.5-2 eV energy range, indicating that they could be suitable for a synergistic coupling with excitons in two-dimensional transition metal dichalcogenides materials or for designing nanoscale sensing platforms based on near-field enhancement over a metallic surface.

Grid-connected cabin preheating of Electric Vehicles in cold climates – A non-flexible share of the EV energy use

The number of EVs is increasing globally. In cold climates, it is generally recommended to use electricity from the grid to preheat the EV cabin before using the car, to extend driving ranges, to ensure comfort, and for safety. A majority of such preheating sessions are happening in the morning hours during the winter, when there is also a high demand for other energy use. It is thus important to understand the power loads for grid-connected preheating of EV cabins. This work presents an experimental study, with 51 preheating sessions of five typical EV models during different outdoor temperatures. The results of the study showed that during the preheating sessions, most of the EVs had a power use of between 3 and 8 kW initially, which was reduced to about 2 to 4 kW after a 10 to 20 min initial period. For most of the sessions, the preheating lasted between 15 and 45 min. The preheating energy use was found to be up to 2 kWh for most EVs, with a maximum of 5 kWh. Multiple linear regression models were developed, to investigate the relationship between various variables and the energy use for preheating. Finally, hourly energy loads for EV cabin preheating were compared to other energy loads in apartment buildings. The power and energy loads for preheating EV cabins are affected by a number of parameters, such as the specific EV, charge point, preheating duration, temperature levels, and user habits.

Structural and elastic investigations of ternary perovskite BaMF3 (M=Ag,Cu) compounds

Herein the first-principles modeling within the DFT framework is used to investigate the structural, optoelectronic, elastic, and thermoelectric properties of BaMF3 (M = Ag and Cu) ternary halide Perovskites compounds. The computed tolerance factors for BaAgF3 and BaCuF3 are 0.919 and 0.991 respectively, indicating that the cubic crystal phase of these selected compounds is thermodynamically and mechanically stable. It is found that both the compounds are structurally stable according to the Birch-Murnaghan fit curve for optimization. The IRelast package is used for investigating the elastic properties of both cubic compounds and the findings show that these compounds are mechanically stable, scratch-resistant, ductile, anisotropic, and resistant to plastic deformation. The Trans-Blaha modified Becke-Johnson (TB-mBJ) approximation is employed to determine electronic properties with accuracy and precision. The electronic-band structure analysis depicts a narrow band gap semiconductor nature of BaAgF3 and BaCuF3 compounds which displays indirect band gaps of 0.2 eV for BaAgF3 and 0.3 eV for BaCuF3 at the high symmetrical points from (Γ–M). Furthermore, the computations of total densities of states (TDOS) and partial densities of states (PDOS) are carried out to determine how different states contribute to the various band structures. The optical characteristics of BaAgF3 and BaCuF3 are comprehensively examined in 0-40 eV energy ranges. The selected materials possess high optical conduction and absorption coefficients at the high level of photon energies and show transparency at low incident photon energy ranges. The investigations of optical properties led us to the conclusion that BaAgF3 and BaCuF3 are suitable to use in high-frequency UV devices. The thermoelectric properties show that both materials hold high-power factors, electrical conductivity, and figures of merit (ZT), indicating that they are good thermoelectric materials. This is the first theoretical computational systematic analysis of structural, optoelectronic, elastic, and thermoelectric properties of BaMF3 (M= Ag and Cu) that will be experimentally validated to our knowledge.

Molecular engineering of Pyran‐fused acceptor–donor–acceptor‐type non‐fullerene acceptors for highly efficient organic solar cells—A density functional theory approach

AbstractThe end‐capped modification proves that it is an excellent attempt to improve the solar cells performances. Therefore, nowadays, many researchers are working to design new molecules for potential use in organic photovoltaics. Herein, we have modified new molecules (SA1–SA5) from the reference (R) for fullerene‐free solar cells. These novel molecules have lower excitation energy levels that make the easier excitation in the excited state. Additionally, SA1 to SA5 molecules exhibit excellent charge mobility due to the modification of an efficient core units. Geometric and physiochemical investigations indicate that the modeled molecules are beneficial for efficient organic solar cells. The estimation of frontier molecular orbitals analysis, reorganizational energy, photovoltaic characteristics, and charge transmission calculations was done using density functional theory calculations with B3LYP/6‐31G (d, p) basis set. Among all designed molecules, SA3 has emerged as the preferred choice because of its outstanding photovoltaic characteristics, which include a minimal bandgap of 2.03 eV and reorganization energy of electron and holes of 0.0095 and 0.0077 eV, correspondingly. The designed materials (SA1–SA5) displayed a high λ max values, that is, 693.54 nm (in gas) and 679.63 nm (in chloroform). This theoretical framework suggests that the required photovoltaic properties may be efficiently obtained by remodeling the new molecules.

Synthesis, characterization of dialkylated erythrosin B derivatives and their utility as a propitious anti-microbial agent

The development of small molecule based drugs as an antimicrobial agent is an important area of research nowadays. In the present work, two new molecular entities based on dialkylated erythrosin B has been synthesized via Arbuzov type of rearrangement using dialkyl sulphite as a reagent in the presence of Et3N. Ethyl and methyl based dialkylated derivatives of erythrosin B were characterized using 1H NMR, 13C NMR and HRMS data. Keeping in mind the biological safety of erythrosin B, synthesized derivatives were checked for their antimicrobial activity against the microbial strains Escherichia coli (E.coli). The two were found to be effective against the E. coli with the antimicrobial activity similar to that of Ampicillin. Further, the trend of antimicrobial activity has been supported by DFT data analysis and it was observed that compound, B with low HOMO (–5.93 eV) and LUMO (–3.11 eV) energies is a better antimicrobial agent than compound A.

Biphenylene Nanotube: A Promising Anode Material for Sodium‐Ion Batteries

AbstractThe properties of pristine and boron‐doped biphenylene nanotubes (BPNT and BBPNT, respectively) as anode materials for sodium storage are studied using density functional theory (DFT). To this end, the electronic properties, adsorption energy, diffusion energy barrier, open‐circuit voltage (OCV), and theoretical capacity are evaluated. The density of states calculations indicate that BPNT and BBPNT with zero band gap have a metallic character, which is critical for electron transferring in electrode materials. The calculation of adsorption energies suggests that the inside of the tube has better adsorption than the outside. Also, doping with boron improves the adsorption inside and outside the nanotube. Sodium ion sees three ways to penetrate from the outside to the inside of the tube. Calculations illustrate that the bigger ring with eight atoms with a 7.08 eV energy barrier, compared to the other cavities, is more appropriate for diffusion. This energy decreases to 5.84 eV after boron doping. The OCV profile of BBPNT confirms that this structure is in the acceptable voltage range for sodium‐ion batteries (SIBs). Finally, this work obtains a theoretical capacity of 403.82 mAh g−1 (without sodium clustering) for BBPNT, which confirms the potential of this structure for use in SIBs.

Unveiling the Catalytic Potential of Topological Nodal-Line Semimetal AuSn4 for Hydrogen Evolution and CO2 Reduction

In recent years, the correlation between the existence of topological electronic states in materials and their catalytic activity has gained increasing attention, due to the exceptional electron conductivity and charge carrier mobility exhibited by quantum materials. However, the physicochemical mechanisms ruling catalysis with quantum materials are not fully understood. Here, we investigate the chemical reactivity, ambient stability, and catalytic activity of the topological nodal-line semimetal AuSn4. Our findings reveal that the surface of AuSn4 is prone to oxidation, resulting in the formation of a nanometric SnO2 skin. This surface oxidation significantly enhances the material's performance as a catalyst for the hydrogen evolution reaction in acidic environments. We demonstrate that the peculiar atomic structure of oxidized AuSn4 enables the migration of hydrogen atoms through the Sn-O layer with a minimal energy barrier of only 0.19 eV. Furthermore, the Volmer step becomes exothermic in the presence of Sn vacancies or tin-oxide skin, as opposed to being hindered in the pristine sample, with energy values of -0.62 and -1.66 eV, respectively, compared to the +0.46 eV energy barrier in the pristine sample. Our model also suggests that oxidized AuSn4 can serve as a catalyst for the hydrogen evolution reaction in alkali media. Additionally, we evaluate the material's suitability for the carbon dioxide reduction reaction, finding that the presence of topologically protected electronic states enhances the migration of hydrogen atoms adsorbed on the catalyst to carbon dioxide.

Design and Implementation of a Futuristic EV Energy Trading System (FEETS) Connected with Buildings, PV, and ESS for a Carbon-Neutral Society

To realize carbon neutrality, understanding the energy consumed in the building sector, which is more than that in other sectors, such as industry, agriculture, and commerce, is pivotal. Approximately 37% of energy consumption belongs to the building sector, and management of building energy is a critical factor. In this paper, we present an energy sharing scenario for energy stabilization, assuming that electric vehicles and their charging stations are widely distributed in the future. Consequently, fewer fuel cars will exist, and electric cars will become the major mode of transportation. Therefore, it is essential to install charging stations for electric vehicles in the parking lots of future buildings, and business models are expected to expand. In this paper, we introduce a future energy stabilization mechanism for peak power management in buildings and present a platform that entails connection-based energy trading technology based on a scenario. We also propose an energy supply strategy to prevent excess prices incurred due to peak consumption. Then, we analyzed the electricity bill for one month through scenario-based simulations of an existing building and the proposed system. When applying the proposed system, we derived a result that can reduce electricity rates by 38.3% (best case) to 78.5% (worst case) compared with the existing rates.

Ionizing photon production and escape fractions during cosmic reionization in the TNG50 simulation

ABSTRACTIn this work, we investigate the dependence of the escape fraction of ionizing photons, fesc, on various galaxy and host halo properties during the epoch of reionization. We post-process the TNG50 magnetohydrodynamical simulation from the IllustrisTNG project using the three-dimensional multifrequency radiative transfer code CRASH. Our work covers the stellar mass range of 106 ≲ M⋆/M⊙ ≲ 108 at redshifts 6 < z < 10. Adopting an unresolved, cloud-scale escape fraction parameter of unity, the average halo escape fraction fesc increases with mass from ∼0.3 at M⋆ = 106 M⊙ to ∼0.6 at M⋆ = 107.5 M⊙, after which we find hints of a turnover and decreasing escape fractions for even more massive galaxies. However, we demonstrate a strong and non-linear dependence of fesc on the adopted subgrid escape fraction, resulting in uncertainties for the absolute value of the escape fraction. In addition, fesc has significant scatter at fixed mass, driven by diversity in the ionizing photon rate together with a complex relationship between (stellar) source positions and the underling density distribution. The global emissivity is consistent with observations for reasonable cloud-scale absorption values, and haloes with a stellar mass ≲107.5 M⊙ contribute the majority of escaping ionizing photons at all redshifts. Incorporating dust reduces fesc by a few per cent at M⋆ ≲ 106.5 M⊙, and up to 10 per cent for larger haloes. Our multifrequency approach shows that fesc depends on photon energy, and is reduced substantially at E > 54.4 eV versus lower energies. This suggests that the impact of high-energy photons from binary stars is reduced when accounting for an energy-dependent escape fraction.

Effect of nickel impurity on structural, magnetic and electronic properties of WX2MLs (X = S, Se): An ab-initio study

We have studied the spin dependent structural, electronic and magnetic properties of pristine and Ni doped WX2 (X = S, Se) 2D monolayers by using density functional theory (DFT). The doping process improves and control the electronic and magnetic properties of TMDCs which is essential for application in electronics, optoelectronics and spintronics. WX2MLs with Ni impurity shows ferromagnetic behaviour. Spin resolved energy band gap have been observed. The Ni doped WSe2 exhibits the characteristics of half metal with 0.88 (D) and 0.02 (D) eV energy band gap for up and down spin respectively. The WS2ML with Nickel impurity shows 1.03 (I) and 0.17 (D) eV energy band gap for up and down spin respectively. The total magnetic moment of both Ni doped WX2MLs is found to be approximately 4µB which is due to local effect of the dopant. The exclusive combination of magnetic response and narrow bandgap which expedite the application of spintronics and yields magnetic semiconductors.

A frequency item mining based embedded feature selection algorithm and its application in energy consumption prediction of electric bus

In the engineering practice of applying embedded feature selection algorithm to construct EV energy consumption prediction model, the constructed regression learners are often affected by random factors appeared in the process of data set sampling, algorithm initialization, computing platform resource scheduling and so on, which makes the prediction results of multiple regression learners constructed with the same feature combination different. This seriously affects the optimization process of energy consumption prediction model, resulting in the failure to find the optimal feature combination, and reduces the accuracy of the prediction results. To solve this problem, an embedded energy consumption prediction model construction method based on frequency item mining and evolutionary computing was proposed. In this algorithm, the combination of input characteristic variables is regarded as individual in the population, the prediction result of regression model is regarded as the fitness function, and the randomness of fitness function is corrected online by the statistical results of frequency items. Simulation results show that the algorithm solves the interference of randomness appeared in the process of resource scheduling, class library function reference, data set segmentation, etc., ensures the stability of feature combination in the optimization process of the prediction model, and gets accurate prediction results.