Electron Energy Research Articles

Stark shift in a Frost-Musulin quantum dot: Analytical solution

In the research, a quantum dot (QD) under an external magnetic field is theoretically investigated. The confining potential applied to the charge carriers is chosen as the Frost-Musulin (FM) potential model. First, the energy eigenvalues and eigenstates have been analytically obtained by Nikiforov-Uvarov (NU) procedure. Then, an electric field is imposed on the system. The Stark shift effect (SSE) has been calculated and an analytical relation has been obtained in terms of the Jacobi polynomials. The findings show that the shift of electron energy states at large, and small electric fields are different. The shift is small at weak electric fields. The electron energy states decrease with the increment of the electric field. The electron states are increased by enhancing the system size. In summary, the SSE can be tuned by setting the electric field, the potential height, and the size of QD.

Calibrating Cryogenic Temperature of TEM Specimens using EELS

Cryogenic Scanning/Transmission Electron Microscopy has been established as a leading method to image sensitive biological samples and is now becoming a powerful tool to understand materials' behavior at low temperatures. However, achieving precise local temperature calibration at low temperatures remains a challenge, which is especially crucial for studying phase transitions and emergent physical properties in quantum materials. In this study, we employ electron energy loss spectroscopy (EELS) to measure local cryogenic specimen temperatures. We use the temperature-dependent characteristics of aluminum's bulk plasmon peak in EEL spectra, which shifts due to changes in electron density caused by thermal expansion and contraction. We successfully demonstrate the versatility of this method by calibrating different liquid nitrogen cooling holders in various microscopes, regardless of whether a monochromated or non-monochromated electron beam is used. Temperature discrepancies between the actual temperature and the setpoint temperatures are identified across a range from room temperature to 100 K. This work demonstrates the importance of temperature calibrations at intermediate temperatures and presents a straightforward, robust method for calibrating local temperatures of cryogenically-cooled specimens in electron microscopes.

Investigation of the neutron radiation fields inside the accelerator tunnel during operation of the Swiss Light Source (SLS)

The Swiss Light Source (SLS) is a third-generation synchrotron light source with an electron energy of 2.4 GeV. It consists of a linear accelerator, a booster and a storage ring providing light for various applications. As SLS is a high-energy accelerator, its operation is accompanied with production of ionizing radiation fields, including neutrons. This leads to additional challenges from a radiation protection point of view. The long-term investigation of the radiation fields at this accelerator facility can provide useful information for the residual activation studies and optimization of shielding. This work describes measurements of the neutron radiation fields inside the tunnel and results of this study.

Monte Carlo simulations of x-ray energy spectra in kilovoltage radiotherapy using the PENELOPE code

The Monte Carlo method was applied using the PENELOPE code to simulate the transport of particles in two different x-ray tubes. This method is considered the most important and accurate for simulations and calculations in different branches of science, including medical physics. The tubes were modeled according to the manufacturer’s specifications, and the simulations were divided into two stages due to the computational time. The scope of the work was to obtain in greater detail photon spectra of different qualities of beams in the orthovoltage range used in radiotherapy, since few works have, yet been developed for this energy range. A detailed analysis was carried out by comparing to the spectra results obtained using the SpekCalc software for the different qualities of radiation in the two stages. Mean energy values along with the first and second half-value layers (HVLs) of each energy were determined with the respective differences between them. Different discrepancies were found in most cases, and so it is vitally important to consider each situation independently. Finally, secondary electron energy spectra in the second stage of each quality were presented with their respective mean energies, an important parameter considered in the dose deposition of the different experimental geometries that use such qualities.

Tuning infrared emissivity of GdCoO3 thin films through Fe doping: Fabrication and mechanism

Using polymer-assisted deposition technology, GdCo1-xFexO3 (0 ≤ x ≤ 0.5) porous films with high infrared emissivity at high temperatures were prepared on Si (100) substrates. The composition and calcination temperature of the precursor are determined by TG-DSC. The structure and composition of the films are investigated using Grazing Incidence X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The surface morphology and elemental composition of the films were analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The average infrared emissivity of GdCo1-xFexO3 (0 ≤ x ≤ 0.5) films at different temperatures (100–500 °C) in the range of 8–14 μm has been tested by an infrared emissivity meter. The results show that the GdCoO3 film with Fe doping concentration of 10 % exhibits the highest infrared emissivity of 0.89 at 500 °C. Possible mechanisms for the high infrared emissivity of the films at high temperatures are discussed.

Synthesis and characterization of Xanthan Gum Xanthates and their application for toxic metal ion removal from synthetic wastewater

This study focuses on the synthesis of three grades of xanthates of natural polymeric material Xanthan gum (XG) by reacting it with Carbon disulfide (CS2) in basic medium at room temperature under inert atmosphere. The confirmation of the formation of Xanthan Gum Xanthates (XGX) has been done with the help of Ultraviolet (UV) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, point of zero-charge (PZC), Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM-EDS) studies. DSC and XRD studies have been done to confirm the crystalline nature of the xanthates. The removal of Cu2+and Co2+ from the prepared grades was found to be 86.7%, 89.9% and 93.6% for Cu2+ and 86.1%, 88.8% and 93.1% for Co2+ respectively. Therefore, these xanthates can be employed for the eradication of such toxic metal ions from their synthetic solutions. The adsorption capacities of three grades of xanthates viz. XGX1, XGX2, and XGX3 were found to be 319.48, 303.03, and 325.73 mg/g for Cu(II) and 238.66, 246.91, and 230.41 mg/g and for Co(II) respectively, which are better than the adsorption capacities reported for various other adsorbents in literature.

Preparation and NOx Reduction Performance of Ag-Ni-TiO2/Cordierite Catalyst for HC-SCR System

Selective catalytic reduction (SCR) technology in diesel engines is an exhaust after treatment system used for abatement of nitrogen oxide (NOx) emissions. In order to synthesize Ag-Ni-TiO2/Cordierite catalyst in the conducted study, a solution including silver nitrate (AgNO3), titanium dioxide (TiO2), and nickel (II) nitrate hexahydrate (Ni(NO3)2·6H2O) were used in the coating of the cordierite (2Al2O3-5SiO2-2MgO) main carrier structure. The prepared catalyst was characterized for morphological characteristics via scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analysis. The NOx reduction measurements as catalytic was carried out at 20 °C intervals in the temperature range from 190 to 270°C at 1 kW and 3 kW motor loads and under 30000 h−1 space velocity (SV). Ethanol was used as a reductant during the experiments. As a results of the measurements, it was seen that the Ag-Ni-TiO2/Cordierite catalyst exhibited a good NOx conversion efficiency with 93.8 % at 270°C at 3 kW.

Effect of Discharge Energy on Micro-Arc Oxidation Coating of Zirconium Alloy.

The micro-arc oxidation (MAO) technique was used to grow in situ oxidation coating on the surface of R60705 zirconium alloy in Na2SiO3, Na2EDTA, and NaOH electrolytes. The thickness, surface morphology, cross-section morphology, wear resistance, composition, and structure of the micro-arc oxidation coating were analyzed by an eddy current thickness measuring instrument, XPS, XRD, scanning electron microscopy, energy spectrometer, and wear testing machine. The corrosion resistance of the coating was characterized by a polarization curve and electrochemical impedance spectroscopy (EIS). The results show that, with the increase in frequency, the single-pulse discharge energy decreases continuously, and the coating thickness shows a decreasing trend, from the highest value of 152 μm at 400 Hz to the lowest value of 87.5 μm at 1000 Hz. The discharge pore size on the surface of the coating gradually decreases, and the wear resistance and corrosion resistance of the coating first increase and then decrease. The corrosion resistance is the best when the frequency is 400 Hz. At this time, the corrosion potential is -0.215 V, and the corrosion current density is 2.546 × 10-8 A·cm-2. The micro-arc oxidation coating of zirconium alloy is mainly composed of monoclinic zirconia (m-ZrO2) and tetragonal zirconia (t-ZrO2), in which the content of monoclinic zirconia is significantly more than that of tetragonal zirconia.

Influence of tin additions on the corrosion passivation of TiZrTa alloy in sodium chloride solutions

Abstract In this study, the fabrication of Ti-12%Zr-4%Ta-2%Sn alloy, Ti-12%Zr-4%Ta-4%Sn alloy, and Ti-12%Zr-4%Ta-6%Sn alloy using powder metallurgy fabrication technique has been carried out. The influence of Sn addition on the corrosion of these alloys after 30 min and 3 days in 3.5% NaCl solution using various techniques has been reported. The Nyquist spectra revealed that boosting Sn content from 2 to 4% and further to 6% increases the corrosion resistance of the alloy through increasing the diameter of the obtained semicircle. Bode spectra also elucidated that the increased percentage of Sn increases the values of the impedance of the interface |Z| and the maximum degree of the phase angle (Φ). It was indicated from the cyclic polarization curves that the increased Sn content increases the passivation of the alloy through decreasing its rate of corrosion and increasing its corrosion resistance. The measured current over time at −0.10 V showed that the alloy with low Sn content, 2%, records the highest currents, which pronouncedly decreases when Sn content increases to 4% and further to 6%. Prolonging the time of exposure from 30 min to 3 days greatly enhances the passivation of the TiZrTaSn alloys due to the formation of mixed oxides of TiO2, ZrO2, TaO2, and SnO2. The results of these electrochemical measurements were confirmed by the surface investigations carried out by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results collectively proved that the uniform corrosion remarkably decreases with the increase in the Sn% and that the pitting corrosion is not likely to take place.

Durable lightweight cementitious composites incorporating rice husk: Accelerated aging studies with acidic and basic solutions

This study investigates the compatibility between cellular concrete (foamed concrete) and natural rice husk to develop high-performance and sustainable sealing materials. Through a bibliographical review we identified challenges in incorporating vegetable fibers into cementitious matrices due to problems related to durability. Prismatic samples of a Reference mixture (foamed concrete) and a Composite with foamed concrete and natural rice husk underwent chemical treatments with acidic and basic solutions to simulate long-term durability. Results show that even after complete organic matter degradation, the composite maintains adequate mechanical performance for sealing walls. Microstructural analyses, including scanning electron microscopy, x-ray diffraction, x-ray fluorescence, and energy dispersive spectroscopy, revealed that silica in the rice husk significantly contributes to axial compression strength by forming C–S–H. The degradation of natural polymers results in the formation of calcium carbonate and calcium sulfate dihydrate, mitigating strength loss. This study proves that the composites with natural rice husk and foamed concrete are a viable and durable solution, provided it does not include metallic materials susceptible to corrosion in composition.

Self-consistent calculation of the optical emission spectrum of an argon capacitively coupled plasma based on the coupling of particle simulation with a collisional-radiative model

We report the development of a computational framework for the calculation of the optical emission spectrum of a low-pressure argon capacitively coupled plasma (CCP), which is based on the coupling of a particle-in-cell/Monte Carlo collision simulation code with a diffusion-reaction-radiation code for Ar I excited levels. In this framework, the particle simulation provides the rates of the direct and stepwise electron-impact excitation and electron-impact de-excitation for 30 excited levels, as well as the rates of electron-impact direct and stepwise ionization. These rates are used in the solutions of the diffusion equations of the excited species in the second code, along with the radiative rates for a high number of Ar-I transitions. The calculations also consider pooling ionization, quenching reactions, and radial diffusion losses. The electron energy distribution function and the population densities of the 30 excited atomic levels are computed self-consistently. The calculations then provide the emission intensities that reproduce reasonably well the experimentally measured optical emission spectrum of a symmetric CCP source operated at 13.56 MHz with 300 V peak-to-peak voltage, in the 2–100 Pa pressure range. The accuracy of the approach appears to be limited by the one-dimensional nature of the model, the treatment of the radiation trapping through the use of escape factors, and the effects of radiative cascades from higher excited levels not taken into account in the model.

Alternatywne podejście do usuwania/odzyskiwania wybranych metali z wody kopalnianej wypływającej z zalanej kopalni syderytu Nižná Slaná

The objective of this work was the application of innovative method for metals recovery from metalliferous mine water released from the flooded siderite ore deposit Nižná Slaná. Although the metals contained in mine drainage are considered environmental pollutants, they may also be recognised as valuable resources. Several techniques can be used to obtain them by precipitation. Conventional processes using alkaline reagents produce huge amounts of mixed sludge with appropriate storage and management requirement, void of possibility of individual metals subsequent processing. This study examined the feasibility of Fe and Mn selective retrieval from real mine water. After oxidation and partial precipitation of iron using hydrogen peroxide, precipitation by sodium hydroxide was applied to the residue iron removal from mine water. In the next step potassium permanganate was used to eliminate manganese by oxidative precipitation. ORP and pH values of processed mine water was recorded in the course of oxidation/precipitation processes. The morphology and elemental composition of obtained products were studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The recovery efficiencies of Fe and Mn from mine water reached 99.87 % and 99.25%, respectively. Target metals were removed with high selectivity to levels that comply with environmental requirements.

The effect of annealing on micro-hardness of molybdenum single crystals

Molybdenum (Mo) crystals exhibit excellent mechanical properties such as high yield strength, high elastic modulus, very high melting point, and excellent corrosion resistance, making them a suitable choice for various industrial applications. The mechanical behaviour of these crystals has been investigated through tension, compression, and indentation experiments. The indentation experiments on annealed Mo single-crystal thin film show an increase in hardness with increase in annealing temperature from 400 °C–650 °C. However, it is not clear whether this behaviour is specific to the Mo thin films or these are applicable to the bulk samples of single crystals also. In order to address these issues, the Vickers indentation experiments are performed on as-received and annealed samples of (100) -, (110) -, and (111) -oriented Mo single crystals. The results show that the low-temperature annealing leads to an increase in micro-hardness by 9% for (100) oriented crystals. The x-ray diffraction (XRD), electron backscatter diffraction (EBSD) and energy dispersive x-ray spectroscopy (EDS) studies have shown that there is a drop in the number of dislocation sources or dislocation density ( ρ ) with no high-angle grain boundary formation or any microstructural changes or any oxide formation. This necessitates to enhance the applied stress required for significant yielding (or yield strength) which results in an increase in the hardness. Based on experimental observations, a hardening mechanism governed by dislocation annihilation during annealing has been proposed in the present study.

Self-Modification of Defective TiO2 under Controlled H2/Ar Gas Environment and Dynamics of Photoinduced Surface Oxygen Vacancies.

In recent years, defective TiO2 has caught considerable research attention because of its potential to overcome the limits of low visible light absorption and fast charge recombination present in pristine TiO2 photocatalysts. Among the different synthesis conditions for defective TiO2, ambient pressure hydrogenation with the addition of Ar as inert gas for safety purposes has been established as an easy method to realize the process. Whether the Ar gas might still influence the resulting photocatalytic properties and defective surface layer remains an open question. Here, we reveal that the gas flow ratio between H2 and Ar has a crucial impact on the defective structure as well as the photocatalyic activity of TiO2. In particular, transmission electron microscopy (TEM) in combination with electron energy loss spectroscopy (EELS) revealed a larger width of the defective surface layer when using a H2/Ar (50 %-50 %) gas mixture over pure H2. A possible reason could be the increase in dynamic viscosity of the gas mixture when Ar is added. Additionally, photoinduced enhanced Raman spectroscopy (PIERS) is implemented as a complementary approach to investigate the dynamics of the defective structures under ambient conditions which cannot be effortlessly realized by vacuum techniques like TEM.

Systematic Engineering of Near-Infrared Small Molecules Based on 4H-Cyclopenta[1,2-b:5,4-b']dithiophene Acceptors for Organic Solar Cells.

Nonfullerene acceptors (NFAs) have emerged as tremendous materials, efficiently advancing bulk-heterojunction organic solar cells (OSCs) technology. Unlike their fullerene counterparts, NFAs offer the unique advantage of finely tunable electronic energy levels and optical characteristics, which correspond to substantial enhancement in power conversion efficiency of OSCs. Herein, we have introduced a new series of near-infrared NFAs (AY1-AY8) to advance this technology further. Our research deeply investigates the structure-property relationship and thoroughly explores the optical, optoelectronics, photophysical, and photovoltaic characteristics of a synthetic reference molecule (R) and the modeled AY1-AY8 NFAs series. We performed advanced quantum chemical simulations using density functional theory (DFT) and time-dependent DFT methods. Additionally, we also estimated key geometric characteristics such as frontier molecular orbitals, hole-electron overlap, density of states, molecular electrostatic potential, molecular excitation and binding energies, transition density matrix, and reorganizational energy of electrons and holes and compared them with those of a synthetic reference molecule (R). Our findings show that all designed materials (AY1-AY8) exhibit red-shift absorption, improved electronic charge mobility, and low binding and excitation energies compared to R. Notably, these designed materials (AY1-AY8) display significantly narrower electronic energy gaps (E g 1.89-1.71 eV), indicating enhanced charge shifting from the highest occupied molecular orbital to lowest unoccupied molecular orbital and broadening of the absorption spectrum. Moreover, we also revealed a comprehensive study of the donor/acceptor complex of PTB7-Th/AY8 to understand charge shifting between donor and acceptor molecules. Therefore, we strongly recommend this designed (AY1-AY8) series to the experimentalists for the future development of highly efficient OSC devices.

Formation processes of iron-based layered hydroxide in acid mine drainage and its implications for in-situ arsenate immobilization: Insights and mechanisms

The immobilization of arsenate in transformed minerals depends on their states in acid mine drainage (AMD). In this study, an iron-based layer hydroxide mineral was derived from the transformation of ferrihydrite under co-existing Mg2+ ions in AMD. The immobilization behavior of arsenate on the mineralized LDHm and pre-prepared LDHad was distinguished. 99 % immobilization efficiency was achieved from the mineralized LDHm, maintaining stability without subsequent releases, across initial arsenate concentrations ranging from 10 to 60 mg/L. LDHm outperformed the pre-prepared LDHad, which was synthesized from AMD for arsenate adsorption. Electron energy loss spectroscopy line profiles revealed predominant incorporation of arsenate in the LDHm structure, supported by higher bulk As signals within LDHm. Density functional theory calculations indicated primary arsenate incorporation into LDHm, forming stable bonds with lower energy activation barriers. Importantly, LDHm exhibited a superior electron rearrangement configuration, resulting in enhanced electron state activity and affinity for arsenate. In contrast, arsenate adsorption predominantly occurred on the pre-prepared LDHad, with notable As signals detected particularly at the edges. Adsorption energy evaluation indicated arsenate preference for bonding to Fe3+ sites on LDHad. These findings provide important insights into the role of stable LDH-like minerals for long-term arsenate immobilization in the natural AMD attenuation processes.

Green synthesis and characterization of AgNPs, liposomal loaded AgNPs and ZnPcS4 photosensitizer for enhanced photodynamic therapy effects in MCF-7 breast cancer cells

Breast cancer remains a formidable challenge in oncology despite significant advancements in treatment modalities. Conventional therapies such as surgery, chemotherapy, radiation therapy, and hormonal therapy have been the mainstay in managing breast cancer for decades. However, a subset of patient's experiences treatment failure, leading to disease recurrence and progression. Therefore, this study investigates the therapeutic potential of green-synthesized silver nanoparticles (AgNPs) using an African medicinal plant (Dicoma anomala methanol root extract) as a reducing agent for combating breast cancer. AgNPs were synthesized using the bottom-up approach and later modified with liposomes (Lip) loaded with photosensitizer (PS) zinc phthalocyanine tetrasulfonate (Lip@ZnPcS4) using thin film hydration method. The successful formation and Lip modification of AgNPs, alongside ZnPcS4, were confirmed through various analytical techniques including UV–Vis spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Following a 24 h treatment period, MCF-7 cells were assessed for viability using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT viability assay), cell death analysis using mitochondrial membrane potential (MMP) (ΔΨm), Annexin V-fluorescein isothiocyanate (FITC)-propidium iodide (PI) kit, and caspase- 3, 8 and 9 activities. The experiments were repeated four times (n = 4), and the results were analyzed using SPSS statistical software version 27, with a confidence interval set at 0.95. The synthesized nanoparticles and nanocomplex, including AgNPs, AgNPs-Lip, Lip@ZnPcS4, and AgNPs-Lip@ZnPcS4, exhibited notable cytotoxicity and therapeutic efficacy against MCF-7 breast cancer cells. Notably, the induction of apoptosis, governed by the upregulation of apoptotic proteins i.e., caspase 8 and 9 activities. In addition, caspase 3 was not expressed by MCF-7 cells in both control and experimental groups. Given the challenging prognosis associated with breast cancer, the findings underscore the promise of liposomal nanoformulations in cancer photodynamic therapy (PDT), thus warranting further exploration in clinical settings.

Formulation of tattoo paints from the assemblage of the Upper Paleolithic site of Ushki V (Kamchatka)

In recent times, the practice of body modification in sociocultural, psychological, and art studies contexts has gained a new impetus for research. This article presents the results of the analysis of pigments found on the sur-face of stone artifacts identified as tattooing tools from the assemblage of layer VII of the Upper Paleolithic site of Ushki V (13–12 ka calBP, Kamchatka Peninsula). The aim of this study is to reconstruct the formulation of paints discovered on the surface of stone tools from the collection of Ushki V, that could have been used for tattooing. The reconstruction was carried out by means of determining the composition and microstructure of the paints using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDX). The conclusions about the structure of colouring substances and the composition of paints are based on the element mapping method, which allows determination of the relationships of chemical elements and establishing the chemical com-position of individual components of the microstructure. Seven samples of red and yellow paint from the surface of six tools (carvers) have been thoroughly analysed. As a result, it has been found that three recipes were used for the manufacture of the pigments. The first (red paint) was based on mixing crushed mineral pigment (hema-tite) with organic binder of animal or vegetable origin. The second (yellow paint) implied the use of limonite, or-ganic binder and a thickener (aluminosilicate material or crushed bone). The third recipe (dark orange paint) in-cluded the compound of limonite and organic binder without thickener. The comparison of the formulations with previously obtained data on the analysis of paints from Ushki V allows for the conclusion that there were continu-ous technological traditions determined by the desired color and purpose of the paint. It has been established that the formulations have analogies both among the assemblages of other Stone Age sites of Eurasia and in ethno-graphic materials. Theoretical and practical significance of this research lies within extending of focused studies of the culture of peoples of the North and initiating of comparative research into similar Late Paleolithic and Neolithic complexes in the territories adjacent to Kamchatka and in the New World.

Response of selenium pools to drought stress by regulating physio‑biochemical attributes and anatomical changes in Gentiana macrophylla

Selenium (Se), as a vital stress ameliorant, possesses a beneficial effect on mediating detrimental effects of environmental threats. However, the mechanisms of Se in mitigating the deleterious effects of drought are still poorly understood. Gentiana macrophylla Pall. is a well-known Chinese medicinal herb, and its root, as the main medicinal site, has significant therapeutic effects. The purpose of this experiment was to investigate the functions of Se on the seedling growth and physiobiochemical characteristics in G. macrophylla subjected to drought stress. The changes in microstructure and chloroplast ultrastructure of G. macrophylla leaves under drought exposure were characterized by scanning electron microscopy (SEM), scanning electron microscopes and energy dispersive X-Ray spectroscope (SEM-EDX), and transmission electron microscopy (TEM), respectively. Results revealed that drought stress induced a notable increase in oxidative toxicity in G. macrophylla, as evidenced by elevated levels of hydrogen peroxide (H2O2), lipid peroxidation (MDA), enhanced antioxidative response, decreased plant photosynthetic function, and inhibited plant growth. Chloroplasts integrity with damaged membranes and excess osmiophilic granule were observed in the drought-stressed plants. Se supplementation notably recovered the stomatal morphology, anatomical structure damage, and chloroplast ultrastructure of G. macrophylla leaves caused by drought exposure. Exogenous Se application markedly enhanced SPAD, photosynthetic stomatal exchange parameters, and photosystem II activity. Se supplementation significantly promoted the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT), while reducing levels of MDA, superoxide anion (O2–.) and H2O2, and improving membrane integrity. Furthermore, the ameliorative effects of Se were also suggested by increased contents of osmotic substances (soluble sugar and proline), boosted content of gentiopicroside and loganinic acid in roots, and alleviated the inhibition in plant growth and biomass. Fourier transform infrared (FTIR) analysis of Se-treated G. macrophylla roots under drought stress demonstrated that Se-stimulated metabolites including O-H, C-H, N-H, C-N, and CO functional groups, were involved in resisting drought stress. Correlation analysis indicated an obvious negative correlation between growth parameters and MDA, O2–. and H2O2 content, while a positive correlation with photosynthetic gas exchange parameters. Principal component analysis (PCA) results explained the total variance into two principal components contributing the maximum (93.50 %) among the drought exposure with or without Se due to the various experiment indexes. In conclusion, Se exerts beneficial properties on drought-induced detrimental effects in G. macrophylla by relieving oxidative stress, improving photosynthesis indexes, PSII activity, regulating anatomical changes, altering levels of gentiopicroside and loganinic acid, and promoting growth of drought-stressed G. macrophylla.

Interpretable Data‐Driven Descriptors for Establishing the Structure‐Activity Relationship of Metal‐Organic Frameworks Toward Oxygen Evolution Reaction

The development of readily accessible and interpretable descriptors is pivotal yet challenging in the rational design of metal‐organic framework (MOF) catalysts. This study presents a straightforward and physically interpretable activity descriptor for the oxygen evolution reaction (OER), derived from a dataset of bimetallic Ni‐based MOFs. Through an artificial‐intelligence (AI) data‐mining subgroup discovery (SGD) approach, a combination of the d‐band center and number of missing electrons in eg states of Ni, as well as the first ionization energy and number of electrons in eg states of the substituents, is revealed as a gene of a superior OER catalyst. The found descriptor, obtained from the AI analysis of a dataset of MOFs containing 3‐5d transition metals and 13 organic linkers, has been demonstrated to facilitate in‐depth understanding of structure–activity relationship at the molecular orbital level. The descriptor is validated experimentally for 11 Ni‐based MOFs. Combining SGD with physical insights and experimental verification, our work offers a highly efficient approach for screening MOF‐based OER catalysts, simultaneously providing comprehensive understanding of the catalytic mechanism.