Reaction Mechanism of Rapid CO Electroreduction to Propylene and Cyclopropane (C3+) over Triple Atom Catalysts.

The carbon monoxide reduction reaction (CORR) toward C2+ and C3+ products such as propylene and cyclopropane can not only reduce anthropogenic emissions of CO and CO2 but also produce value-added organic chemicals for polymer and pharmaceutical industries. Here, we introduce the concept of triple atom catalysts (TACs) that have three intrinsically strained and active metal centers for reducing CO to C3+ products. We applied grand canonical potential kinetics (GCP-K) to screen 12 transition metals (M) supported by nitrogen-doped graphene denoted as M3N7, where M stands for Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, and Au. We sought catalysts with favorable CO binding, hydrogen binding, and C-C dimerization energetics, identifying Fe3N7 and Ir3N7 as the best candidates. We then studied the entire reaction mechanism from CO to C3H6 and C2H4 as a function of applied potential via, respectively, 12-electron and 8-electron transfer pathways on Fe3N7 and Ir3N7. Density functional theory (DFT) predicts an overpotential of 0.17 VRHE for Fe3N7 toward propylene and an overpotential of 0.42 VRHE toward cyclopropane at 298.15 K and pH = 7. Also, DFT predicts an overpotential of 0.15 VRHE for Ir3N7 toward ethylene. This work provides fundamental insights into the design of advanced catalysts for C2+ and C3+ synthesis at room temperature.

Facet-Dependent Oxygen Evolution Reaction Activity of IrO2 from Quantum Mechanics and Experiments.

The diversity of chemical environments present on unique crystallographic facets can drive dramatic differences in catalytic activity and the reaction mechanism. By coupling experimental investigations of five different IrO2 facets and theory, we characterize the detailed elemental steps of the surface redox processes and the rate-limiting processes for the oxygen evolution reaction (OER). The predicted complex evolution of surface adsorbates and the associated charge transfer as a function of applied potential matches well with the distinct redox features observed experimentally for the five facets. Our microkinetic model from grand canonical quantum mechanics (GC-QM) calculations demonstrates mechanistic differences between nucleophilic attack and O-O coupling across facets, providing the rates as a function of applied potential. These GC-QM calculations explain the higher OER activity observed on the (100), (001), and (110) facets and the lower activity observed for the (101) and (111) facets. This combined study with theory and experiment brings new insights into the structural features that either promote or hinder the OER activity of IrO2, which are expected to provide parallels in structural effects on other oxide surfaces.

CO2-Promoted Electrocatalytic Reduction of Chlorinated Hydrocarbons.

Electrochemical reactions and their catalysis are important for energy and environmental applications, such as carbon neutralization and water purification. However, the synergy in electrocatalysis between CO2 utilization and wastewater treatment has not been explored. In this study, we find that the electrochemical reduction of chlorinated organic compounds such as 1,2-dichloroethane, trichloroethylene, and tetrachloroethylene into ethylene in aqueous media, which is a category of challenging reactions due to the competition of H2 evolution, can be substantially enhanced by simultaneously carrying out the reduction of CO2 on an easily prepared and cost-effective Cu metal catalyst. In the case of 1,2-dichloroethane dechlorination, a 6-fold improvement in Faradaic efficiency and a 19-fold increase in partial current density are demonstrated. Through electrochemical kinetic studies, in situ Raman spectroscopy, and computational simulations, we further find that CO2 reduction reduces hydrogen coverage on the Cu catalyst, which not only exposes more active sites for the dechlorination reaction but also enhances the effective reductive potential on the catalyst surface and reduces the kinetic barrier of the rate-determining step.

Genetic Insights into the Extremely Dwarf Hibiscus syriacus var. micranthus: Complete Chloroplast Genome Analysis and Development of a Novel dCAPS Marker.

This study explored the chloroplast (cp) genomes of three Hibiscus syriacus (HS) specimens endemic to Korea possessing unique ornamental and conservation values: the dwarf H. syriacus var. micranthus (HSVM), renowned for its small stature and breeding potential; HS 'Tamra', a cultivar from Korea's southernmost islands, noteworthy for its distinctive beauty; and HS Natural Monument no. 521 (N.M.521), a specimen of significant lifespan and height. Given the scarcity of evolutionary studies on these specimens, we assembled and analyzed their cp genomes. We successfully assembled genomes spanning 160,000 to 160,100 bp and identified intraspecific variants. Among these, a unique ATA 3-mer insertion in the trnL-UAA region was identified in HSVM, highlighting its value as a genetic resource. Leveraging this finding, we developed a novel InDel dCAPS marker, which was validated across 43 cultivars, enhancing our ability to distinguish HSVM and its derivatives from other HS cultivars. Phylogenetic analysis involving 23 Malvaceae species revealed that HSVM forms a clade with woody Hibiscus species, closely associating with N.M.520, which may suggest a shared ancestry or parallel evolutionary paths. This investigation advances our understanding of the genetic diversity in Korean HS and offers robust tools for accurate cultivar identification, aiding conservation and breeding efforts.

Improving Oxygen Reduction Performance of Surface-Layer-Controlled Pt-Ni Nano-Octahedra via Gaseous Etching.

This study demonstrates an atomic composition manipulation on Pt-Ni nano-octahedra to enhance their electrocatalytic performance. By selectively extracting Ni atoms from the {111} facets of the Pt-Ni nano-octahedra using gaseous carbon monoxide at an elevated temperature, a Pt-rich shell is formed, resulting in an ∼2 atomic layer Pt-skin. The surface-engineered octahedral nanocatalyst exhibits a significant enhancement in both mass activity (∼1.8-fold) and specific activity (∼2.2-fold) toward the oxygen reduction reaction compared with its unmodified counterpart. After 20,000 potential cycles of durability tests, the surface-etched Pt-Ni nano-octahedral sample shows a mass activity of 1.50 A/mgPt, exceeding the initial mass activity of the unetched counterpart (1.40 A/mgPt) and outperforming the benchmark Pt/C (0.18 A/mgPt) by a factor of 8. DFT calculations predict this improvement with the Pt surface layers and support these experimental observations. This surface-engineering protocol provides a promising strategy for developing novel electrocatalysts with improved catalytic features.

Efficient electrocatalytic valorization of chlorinated organic water pollutant to ethylene.

Electrochemistry can provide an efficient and sustainable way to treat environmental waters polluted by chlorinated organic compounds. However, the electrochemical valorization of 1,2-dichloroethane (DCA) is currently challenged by the lack of a catalyst that can selectively convert DCA in aqueous solutions into ethylene. Here we report a catalyst comprising cobalt phthalocyanine molecules assembled on multiwalled carbon nanotubes that can electrochemically decompose aqueous DCA with high current and energy efficiencies. Ethylene is produced at high rates with unprecedented ~100% Faradaic efficiency across wide electrode potential and reactant concentration ranges. Kinetic studies and density functional theory calculations reveal that the rate-determining step is the first C-Cl bond breaking, which does not involve protons-a key mechanistic feature that enables cobalt phthalocyanine/carbon nanotube to efficiently catalyse DCA dechlorination and suppress the hydrogen evolution reaction. The nanotubular structure of the catalyst enables us to shape it into a flow-through electrified membrane, which we have used to demonstrate >95% DCA removal from simulated water samples with environmentally relevant DCA and electrolyte concentrations.

Complete chloroplast genome sequence of Hibiscus trionum Linnaeus 1753 (Malvaceae).

Hibiscus trionum L. is an annual herbaceous plant belonging to the Malvaceae family. It is native to Central Africa, however, is now naturalized in Europe and Asia including Korea. Here, we report the complete chloroplast genome assembly of H. trionum. The complete chloroplast genome comprises 160,530 bp and is divided into four typical regions: a large single-copy region of 89,272 bp, a pair of inverse repeats of 26,152 bp each, and a small single-copy region of 18,954 bp. A total of 131 genes were identified in this chloroplast, of which 86 were protein-coding, 37 were tRNA, and 8 were rRNA genes. The results of this study will serve as a key reference for further research on Hibiscus speciation.

Nutritional composition and phytochemical screening in different parts of Hibiscus syriacus L.

As the national flower of Korea, the Hibiscus syriacus L. (Rose of Sharon) is symbolic in its abundance and is a prominent feature of Korean culture. H. syriacus has played an important role in Korea, not only as an ornamental plant but also as an essential ingredient in folk remedies through its various parts. This study aimed to characterize the nutritional and biochemical composition of each plant unit of H. syriacus "Wonhwa." The units are namely: the petals, leaves, roots, and sprouts from its seeds. According to the results each unit produced, the sprouts had the highest content of amino acids and fatty acids which adhere to the requirements of nutritionally excellent food ingredients. The petals produced high quantities of glucose, sucrose, and fumaric acid, with the highest antioxidant activity among the four units. The main bioactive compounds detected in H. syriacus extracts in the four units were o-coumaric acid, p-coumaric acid, schaftoside, isoschaftoside, apigenin-6-C-glucoside-7-o-glucoside, and kaempferol-3-O-galactoside-7-O-rhamnoside. Overall, the highest number of bioactive compounds, 2 phenolic acids and 22 flavonoids, were identified in the petals. These results suggest the possibility of excellent pharmacological activity in the petals.

Interpretable Deep Learning Model for Analyzing the Relationship between the Electronic Structure and Chemisorption Property.

The use of machine learning (ML) is exploding in materials science as a result of its high predictive performance of material properties. Tremendous trainable parameters are required to build an outperforming predictive model, which makes it impossible to retrace how the model predicts well. However, it is necessary to develop a ML model that can extract human-understandable knowledge while maintaining performance for a universal application to materials science. In this study, we developed a deep learning model that can interpret the correlation between surface electronic density of states (DOSs) of materials and their chemisorption property using the attention mechanism that provides which part of DOS is important to predict adsorption energies. The developed model constructs the well-known d-band center theory without any prior knowledge. This work shows that human-interpretable knowledge can be extracted from complex ML models.

Linalyl acetate restores colon contractility and blood pressure in repeatedly stressed-ulcerative colitis rats.

BACKGROUND: Ulcerative colitis (UC) is related to stress, but few studies have evaluated the influence of stress on factors affecting colon contractility in rats with UC. Also, there have been no studies investigating beneficial effects of linalyl acetate (LA), the major component of lavender essential oil, in repeatedly stressed-ulcerative colitis rats. Therefore, we investigated the differences in factors affecting colon contractility of UC rats with or without repeated restraint stress (RRS) and the effects of LA on these parameters in repeatedly stressed-UC rats. METHODS: Rats were assigned to following groups: control, RRS, UC, RRS+UC, and RRS+UC treated with LA or sulfasalazine. To induce UC, rats were administered 2% dextran sodium sulfate (DSS) water on days 1-5, followed by tap water on days 6-15 and DSS water on days 16-20. RRS was induced by immobilizing rats for 2 hr/day on days 1-20. LA or sulfasalazine were daily administered on days 16-20. RESULTS: Disease activity index (DAI) was markedly increased in RRS+UC. Serum interleukin-6 levels and acetylcholine-induced colon contraction were higher in RRS+UC than in control, RRS and UC. Colon nitrite levels also significantly increased in RRS+UC compared to the control and RRS. Blood pressure (BP) was higher in RRS+UC than in the control and UC. Both LA and sulfasalazine was effective in decreasing DAI, colon nitrite levels, acetylcholine-induced colon contraction in RRS+UC. Sulfasalazine significantly reduced serum IL-6 levels in RRS+UC with decreasing tendency in RRS+UC treated by LA. Only LA significantly reduced BP in RRS+UC. CONCLUSIONS: Our findings emphasize the importance of stress management in UC patients. Also, LA may be beneficially used in repeatedly stressed-UC patients with high BP.

Experimental and Theoretical Comparison of Potential-dependent Methylation on Chemically Exfoliated WS2 and MoS2.

Reductant-activated functionalization is shown to enhance the methylation of chemically exfoliated MoS2 (ceMoS2) and ceWS2 by introducing excess negative charge to facilitate a nucleophilic attack reaction. Relative to methylation in the absence of a reductant, the reaction produces a twofold increase in coverage of ceWS2, from 25 to 52% coverage per WS2. However, at every potential, the methyl coverage on ceWS2 was ∼20% lower than that on ceMoS2. We applied grand canonical density functional theory to show that at constant potential, more negative charge is present on 1T'-MoS2 than on 1T'-WS2, making methylation both thermodynamically and kinetically more favorable for 1T'-MoS2 than 1T'-WS2. This effect was moderated when the reactions were compared at constant charge, emphasizing the importance of comparing the reactivity of materials at nominally identical electrode potentials.

Reaction Mechanism and Strategy for Optimizing the Hydrogen Evolution Reaction on Single-Layer 1T' WSe2 and WTe2 Based on Grand Canonical Potential Kinetics.

Transition-metal dichalcogenides (TMDs) in the 1T' phase are known high-performance catalysts for hydrogen evolution reaction (HER). Many experimental and some theoretical studies report that vacant sites play an important role in the HER on the basal plane. To provide benchmark calculations for comparison directly with future experiments on TMDs to obtain a validated detailed understanding that can be used to optimize the performance and material, we apply a recently developed grand canonical potential kinetics (GCP-K) formulation to predict the HER at vacant sites on the basal plane of the 1T' structure of WSe2 and WTe2. The accuracy of GCP-K has recently been validated for single-crystal nanoparticles. Using the GCP-K formulation, we find that the transition-state structures and the concentrations of the four intermediates (0-3 H at the selenium or tellurium vacancy) change continuously as a function of the applied potential. The onset potential (at 10 mA/cm-2) is -0.53 V for WSe2 (experiment is -0.51 V) and -0.51 V for WTe2 (experiment is -0.57 V). We find multistep reaction mechanisms for H2 evolution from Volmer-Volmer-Tafel (VVT) to Volmer-Heyrovsky (VH) depending on the applied potential, leading to an unusual non-monotonic change in current density with the applied potential. For example, our detailed understanding of the reaction mechanism suggests a strategy to improve the catalytic performance significantly by alternating the applied potential periodically.

CO2 reduction on pure Cu produces only H2 after subsurface O is depleted: Theory and experiment.

We elucidate the role of subsurface oxygen on the production of C2 products from CO2 reduction over Cu electrocatalysts using the newly developed grand canonical potential kinetics density functional theory method, which predicts that the rate of C2 production on pure Cu with no O is ∼500 times slower than H2 evolution. In contrast, starting with Cu2O, the rate of C2 production is >5,000 times faster than pure Cu(111) and comparable to H2 production. To validate these predictions experimentally, we combined time-dependent product detection with multiple characterization techniques to show that ethylene production decreases substantially with time and that a sufficiently prolonged reaction time (up to 20 h) leads only to H2 evolution with ethylene production ∼1,000 times slower, in agreement with theory. This result shows that maintaining substantial subsurface oxygen is essential for long-term C2 production with Cu catalysts.

In Silico High-Throughput Screening of Ag-Based Electrocatalysts for Anion-Exchange Membrane Fuel Cells.

The alkaline environment in anion-exchange membrane fuel cells allows the use of Pt-free electrocatalysts, thus reducing the system cost. We performed a theoretical high-throughput study of various low-cost Ag-based oxygen reduction reaction anode electrocatalysts and assessed their catalytic performance using density functional theory. From the Materials Project database, a total of 106 binary Ag alloys were investigated by estimating their heat of formation, dissolution potential, and overpotential on low-index surfaces. We confirmed that EuAg5, BaAg5, and SrAg5 have higher catalytic activities and durabilities than pure Ag. By following the chemical trend of the results, we further proposed LaAg5 and PrAg5, which were not included in the database, as promising candidates. All candidates are in the space group P6/mmm and contain alkaline earth metal or lanthanide elements.

A Study on Real Time IGBT Junction Temperature Estimation Using the NTC and Calculation of Power Losses in the Automotive Inverter System.

This paper proposes a junction temperature estimation algorithm for the insulated gate bipolar transistor (IGBT) based on a power loss calculation and a thermal impedance model for inverter systems. The Simulink model was designed to calculate the power losses of power semiconductor devices and to estimate the junction temperature with a simplified thermal impedance model. This model can estimate the junction temperature up to the transient state, including the steady state. The parameters used to calculate the power losses, the thermal resistance, and the thermal capacitance were optimized for a given inverter to be tested for improving the accuracy. The simulation results and experimental measurement data were compared to verify the proposed junction temperature estimation algorithm. Finally, the algorithm was installed on the inverter controller, and the performance was verified by comparing the real time estimation result with the measured temperature.

Comparative transcriptome analysis during developmental stages of direct somatic embryogenesis in Tilia amurensis Rupr.

Tilia species are valuable woody species due to their beautiful shape and role as honey trees. Somatic embryogenesis can be an alternative method for mass propagation of T. amurensis. However, the molecular mechanisms of T. amurensis somatic embryogenesis are yet to be known. Here, we conducted comparative transcriptional analysis during somatic embryogenesis of T. amurensis. RNA-Seq identified 1505 differentially expressed genes, including developmental regulatory genes. Auxin related genes such as YUC, AUX/IAA and ARF and signal transduction pathway related genes including LEA and SERK were differentially regulated during somatic embryogenesis. Also, B3 domain family (LEC2, FUS3), VAL and PKL, the regulatory transcription factors, were differentially expressed by somatic embryo developmental stages. Our results could provide plausible pathway of signaling somatic embryogenesis of T. amurensis, and serve an important resource for further studies in direct somatic embryogenesis in woody plants.

Sex-specific susceptibility to type 2 diabetes mellitus and preventive effect of linalyl acetate.

AIMS: Biological, psychosocial and lifestyle risk factors interact in the development of type 2 diabetes mellitus (T2DM). To date, the effects of sex, chronic stress (CS) and high-fat diet (HFD) on T2DM and the ability of linalyl acetate (LA) to prevent T2DM have not been determined. This study therefore explored the differential effects of CS and HFD on T2DM, as well as the ability of LA to prevent T2DM development, in male and female rats. MAIN METHODS: T2DM was induced in rats by feeding an HFD and placing them under immobilization stress for 2 h/day for 3 weeks. Low-dose streptozotocin was administered on day 15, and LA was administered for 3 weeks. KEY FINDINGS: Fasting blood sugar (FBS) increased in HFD-fed male, but not female, rats. CS further increased FBS in HFD-fed rats, whereas CS alone did not alter FBS. The homeostatic model assessment-insulin resistance (HOMA-IR) showed results similar to FBS. Serum corticosterone levels markedly increased only in HFD-fed male rats exposed to CS. Pancreas nuclear factor kappa B (NF-κB) levels were higher in HFD-fed male rats exposed to CS than in control rats although there were no sex differences. LA 10 mg/kg significantly reduced FBS, serum insulin, HOMA-IR, and serum corticosterone levels in HFD-fed male rats exposed to CS. LA 10 mg/kg also tended to reduce NF-κB in the pancreas and significantly increased mitochondrial membrane potential (MMP) in the liver. SIGNIFICANCE: Male rats are vulnerable to T2DM induced by CS and HFD, and LA can prevent T2DM in these rats not only by reducing insulin resistance and corticosterone levels but by increasing MMP in the liver.

Sex differences in cardio-metabolic and cognitive parameters in rats with high-fat diet-induced metabolic dysfunction.

IMPACT STATEMENT: Excessive dietary fat intake plays important roles in the process of metabolic dysfunction and increases susceptibilities to chronic diseases such as hypertension. Few previous studies, however, have accurately reflected real-world medical conditions. In addition, studies performed to date have not examined detailed sex-differences in cardio-metabolic and cognitive parameters, precluding the development of sex-tailored interventions for patients with metabolic dysfunction who are susceptible to hypertension and cognitive impairment. In this study, using rats with HFD-induced metabolic dysfunction that made them susceptible to hypertension and cognitive impairment, we demonstrate that male rats show greater impairment of acetylcholine-induced vasorelaxation of the carotid artery and systolic blood pressure compared to female rats. These findings may provide a basis for the early detection of carotid artery dysfunction and systolic blood pressure increase, especially in males.

Lancemaside A from Codonopsis lanceolata prevents hypertension by inhibiting NADPH oxidase 2-mediated MAPK signalling and improving NO bioavailability in rats.

OBJECTIVES: This study investigated whether lancemaside A (LMA) can prevent hypertension and assessed the mechanisms of action of LMA in rats. METHODS: Hypertension was induced by chronic immobilization stress and nicotine administration. Hypertensive vehicle rats were treated with LMA (1, 20, or 40 mg/kg) or nifedipine (10 mg/kg) as a positive control daily for 3 weeks. KEY FINDINGS: In hypertensive vehicle rats, LMA dose-dependently reduced systolic blood pressure. LMA doses of 20 and 40 mg/kg reduced the aortic expression of nicotinamide adenine dinucleotide phosphate oxidase (NOX)2 (both P < 0.01), and 40 mg/kg LMA reduced serum malondialdehyde (P < 0.01). Serum nitrite levels were significantly higher in LMA treated rats than in hypertensive vehicle rats, with LMA doses of 20 and 40 mg/kg reducing the expression of endothelial nitric oxide synthase in rat aortas (P < 0.001 and P < 0.01, respectively). LMA also reduced the aortic levels of nuclear factor kappa B and the activation of the three isoforms of mitogen-activated protein kinase (MAPK). CONCLUSIONS: Lancemaside A prevents hypertension in rats by inhibiting the activation of MAPK signalling and the impairment in nitric oxide bioavailability due to NOX2-mediated oxidative stress. Thus, LMA may act as a preventive agent for hypertension.

Linalyl acetate prevents three related factors of vascular damage in COPD-like and hypertensive rats.

Preventing vascular damage is considered an effective strategy in patients who suffer from chronic obstructive pulmonary disease (COPD) with hypertension. Here, we investigated vascular damage in COPD-like and hypertensive rats, which demonstrated the presence of the three related factors of COPD with hypertension. These include elevated systolic blood pressure (SBP), serum malondialdehyde (MDA) and serum lactate dehydrogenase (LDH), which are positively correlated with vascular damage in patients. In addition to increases in these three related factors, COPD-like and hypertensive rats exhibited increased levels of pro-inflammatory mediators, such as tumor necrosis factor-α, interleukin-6, and matrix metallopeptidase-9 in bronchoalveolar lavage fluid, and enlargement of alveolar airspaces, recapitulating clinical findings in previous studies of patients. Moreover, the appearance of these related factors was prevented by linalyl acetate. Our results provide novel insight into the potential of LA to prevent vascular damage and elevated SBP, serum MDA and serum LDH in COPD with hypertension, and could lead to an alternative strategy for preventing vascular damage for patients who suffered from COPD with hypertension in a clinical setting.