Composition-activity Relationship Research Articles

Component regulation in flower-like FexCoNiP/C nanohybrids as bifunctional efficient electrocatalysts for overall water splitting

Incorporating bi-metal transition metal phosphides (TMPs) with high-valent metal is a powerful method to obtain highly efficient and low-cost bifunctional electrocatalysts in alkaline media for overall water splitting. However, the composition-activity relationship of such incorporation has not been investigated yet due to the challenge in constructing tri-metal TMPs with continuously variable composition while maintaining a homogenous elemental distribution. In this study, we proposed a strategy using a trimetal oleta composite with a homogenous elemental distribution at the molecular scale as an ideal precursor. This precursor was then used to fabricate Fe-incorporated Ni-Co phosphide on a flower-like carbon substrate, resulting in a continuously changeable Fe content (FexNiCoP/C). Benefiting from the fully exposed structure and the incorporation of Fe, the flower-like FexNiCoP/C hybrids exhibited excellent electrocatalytic performance for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). By optimizing the Fe content, the flower-like Fe0.4NiCoP/C hybrid achieved 10 mA/cm2 at a low overpotential of 243 mV for the OER and 107 mV for the HER, respectively. When the optimal Fe0.4NiCoP/C electrodes were employed as the anode and cathode for water electrolysis in an alkaline electrolyte, the electrolyzer achieved 10 mA/cm2 at a low cell voltage of 1.59 V. This work provides an inexpensive, highly active, and durable electrocatalyst, while revealing the composition-activity relationship of FexNiCoP/C for overall water splitting in alkaline media.

Toward Durable CO2 Electroreduction with Cu-Based Catalysts via Understanding Their Deactivation Modes.

The technology of CO2 electrochemical reduction (CO2ER) provides a means to convert CO2, a waste greenhouse gas, into value-added chemicals. Copper is the most studied element that is capable of catalyzing CO2ER to obtain multicarbon products, such as ethylene, ethanol, acetate, etc., at an appreciable rate. Under the operating condition of CO2ER, the catalytic performance of Cu decays because of several factors that alters the surface properties of Cu. In this review, these factors that cause the degradation of Cu-based CO2ER catalysts are categorized into generalized deactivation modes, that are applicable to all electrocatalytic systems. The fundamental principles of each deactivation mode and the associated effects of each on Cu-based catalysts are discussed in detail. Structure- and composition-activity relationship developed from recent in situ/operando characterization studies are presented as evidence of related deactivation modes in operation. With the aim to address these deactivation modes, catalyst design and reaction environment engineering rationales are suggested. Finally, perspectives and remarks built upon the recent advances in CO2ER are provided in attempts to improve the durability of CO2ER catalysts.

LC-MS/MS profiling of Tipuana tipu flower, HPLC-DAD quantification of its bioactive components, and interrelationships with antioxidant, and anti-inflammatory activity: in vitro and in silico approaches

BackgroundFabaceae plays a crucial role in African traditional medicine as a source of large number of important folk medication, agriculture and food plants. In a search of potential antioxidant and anti-inflammatory candidates derived from locally cultivated plants, the flowers of Tipuana tipu (Benth.) Lillo growing in Egypt were subjected to extensive biological and phytochemical studies. The impact of the extraction technique on the estimated biological activities was investigated.MethodsThe flowers were extracted using different solvents (aqueous, methanol, water/methanol (1:1), methanol/methylene chloride (1:1), and methylene chloride). The different extracts were subjected to antioxidant (DPPH, ABTS, and FRAP) and anti-inflammatory (COX-2 and 5-LOX) assays. The methanol extract was assessed for its inhibitory activity against iNOS, NO production, and pro-inflammatory cytokines (NF-KB, TNF-R2, TNF-α, IL-1β, and IL-6) in LPS-activated RAW 264.7 macrophages. The composition-activity relationship of the active methanol extract was further investigated using a comprehensive LC–QTOF-MS/MS analysis. The major identified phenolic compounds were further quantified using HPLC-DAD technique. The affinity of representative compounds to iNOS, COX-2, and 5-LOX target active sites was investigated using molecular docking and molecular dynamics simulations.ResultsThe methanol extract exhibited the highest radical scavenging capacity and enzyme inhibitory activities against COX-2 and 5-LOX enzymes with IC50 values of 10.6 ± 0.4 and 14.4 ± 1.0 µg/mL, respectively. It also inhibited iNOS enzyme activity, suppressed NO production, and decreased the secretion of pro-inflammatory cytokines. In total, 62 compounds were identified in the extract including flavonoids, coumarins, organic, phenolic, and fatty acids. Among them 18 phenolic compounds were quantified by HPLC-DAD. The highest docking scores were achieved by kaempferol-3-glucoside and orientin. Additionally, molecular dynamics simulations supported the docking findings.ConclusionThe flower could be considered a potentially valuable component in herbal medicines owing to its unique composition and promising bioactivities. These findings encourage increased propagation of T. tipu or even tissue culturing of its flowers for bioprospecting of novel anti-inflammatory drugs. Such applications could be adopted as future approaches that benefit the biomedical field.

In Vitro Antioxidant and In Vivo Antigenotoxic Features of a Series of 61 Essential Oils and Quantitative Composition-Activity Relationships Modeled through Machine Learning Algorithms.

The antioxidant activity of essential oils (EOs) is an important and frequently studied property, yet it is not sufficiently understood in terms of the contribution of EOs mixtures' constituents and biological properties. In this study, a series of 61 commercial EOs were first evaluated as antioxidants in vitro, following as closely as possible the cellular pathways of reactive oxygen species (ROS) generation. Hence, EOs were assessed for the ability either to chelate metal ions, thus interfering with ROS generation within the respiratory chain, or to neutralize 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and lipid peroxide radicals (LOO•), thereby halting lipid peroxidation, as well as to neutralize 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid cation radicals (ABTS•+) and hydroxyl radicals (OH•), thereby preventing the ROS species from damaging DNA nucleotides. Showing noteworthy potencies to neutralize all of the radicals at the ng/mL level, the active EOs were also characterized as protectors of DNA double strands from damage induced by peroxyl radicals (ROO•), emerging from 2,2'-azobis-2-methyl-propanimidamide (AAPH) as a source, and OH•, indicating some genome protectivity and antigenotoxicity effectiveness in vitro. The chemical compositions of the EOs associated with the obtained activities were then analyzed by means of machine learning (ML) classification algorithms to generate quantitative composition-activity relationships (QCARs) models (models published in the AI4EssOil database available online). The QCARs models enabled us to highlight the key features (EOSs' chemical compounds) for exerting the redox potencies and to define the partial dependencies of the features, viz. percentages in the mixture required to exert a given potency. The ML-based models explained either the positive or negative contribution of the most important chemical components: limonene, linalool, carvacrol, eucalyptol, α-pinene, thymol, caryophyllene, p-cymene, eugenol, and chrysanthone. Finally, the most potent EOs in vitro, Ylang-ylang (Cananga odorata (Lam.)) and Ceylon cinnamon peel (Cinnamomum verum J. Presl), were promptly administered in vivo to evaluate the rescue ability against redox damage caused by CCl4, thereby verifying their antioxidant and antigenotoxic properties either in the liver or in the kidney.

Exploration of a NiFeV multi-metal compositional space for the oxygen evolution reaction

We performed a high throughput investigation of a Ni, Fe and V library for the oxygen evolution reaction. The study provides insights into the composition-activity relationship and guides rapid design and development of high performing catalysts.

Experimental and theoretical investigations on the anti-perovskite nitrides Co3CuN, Ni3CuN and Co3MoN for ammonia synthesis.

The ammonia synthesis activities of the anti-perovskite nitrides Co3CuN and Ni3CuN have been compared to investigate the possible metal composition-activity relationship. Post-reaction elemental analysis showed that the activity for both nitrides was due to loss of lattice nitrogen rather than a catalytic process. Co3CuN was observed to convert a higher percentage of lattice nitrogen to ammonia than Ni3CuN and was active at a lower temperature. The loss of lattice nitrogen was revealed to be topotactic and Co3Cu and Ni3Cu were formed during the reaction. Therefore, the anti-perovskite nitrides may be of interest as reagents for the formation of ammonia through chemical looping. The regeneration of the nitrides was achieved by ammonolysis of the corresponding metal alloys. However, regeneration using N2 was shown to be challenging. In order to understand the difference in reactivity between the two nitrides, DFT techniques were applied to investigate the thermodynamics of the processes involved in the evolution of lattice nitrogen to the gas phase via conversion to N2 or NH3, revealing key differences in the energetics of bulk conversion of the anti-perovskite to the alloy phase, and in loss of surface N from the stable low-index N-terminated (111) and (100) facets. Computational modelling of the density of states (DOS) at the Fermi level was performed. It was shown that the Ni and Co d states contributed to the density of states and that the Cu d states only contributed to the DOS for Co3CuN. The anti-perovskite Co3MoN has been investigated as comparisons with Co3Mo3N may give an insight into the role structure type plays in the ammonia synthesis activity. The XRD pattern and elemental analysis for the synthesised material revealed that an amorphous phase was present that contained nitrogen. In contrast to Co3CuN and Ni3CuN, the material was shown to have steady state activity at 400 °C with a rate of 92 ± 15 μmol h-1 g-1. Therefore, it appears that metal composition has an influence on the stability and activity of the anti-perovskite nitrides.

Phytochemical analysis and bioactivity of different ethanolic extracts from cannabidiol full-spectrum oil

Industrial hemp is an important economic crop. The extract of its leaves is well-known as cannabidiol full-spectrum oil (CFSO) and has great application potential. But the chemical composition of CFSO is still not clear, which limits its efficient application. Therefore, this work aimed to explore the phytochemical profile and composition-activity relationship of CFSO. The results showed that a total of 12 cannabinoids were identified by HPLC-ESI-MS and they were CBD-C1, CBGVA, CBGA, CBGV, CBDVA, CBG, CBDV, CBDA, CBD, CBD-C4, CBN, and CBT. CBD (559.3 mg/g) was the most abundant component, followed by CBDV (302.4 mg/g) and CBN (31.7 mg/g). Besides, the content of CBDV, CBD, and CBN of different polar extracts increased with the rise of ethanol concentration. The TPC and TFC of the extracts also increased with the rise of ethanol concentration. The extract of 90 % EtOH had the highest TPC (949.21 ± 2.37 mg GAE/g extract) and TFC (267.05 ± 1.21 mg RE/g extract) while the extract of 0 % EtOH displayed the lowest TPC (244.89 ± 2.13 mg GAE/g extract) and TFC (46.26 ± 0.85 mg RE/g extract). Furthermore, as ethanol concentration increased, the cytotoxicity, antioxidant, and antibacterial activities of the extracts had a significant increasing trend. And the correlation analysis demonstrated that the antioxidant activity and cytotoxicity of the extracts were closely related with the phenolic compounds and flavonoids, especially cannabinoids. These findings could provide data support for the application of CFSO.

Promoting Surface Reconstruction of NiFe Layered Double Hydroxide for Enhanced Oxygen Evolution

AbstractA dynamic surface reconstruction of oxide electrocatalysts in alkaline media is widely observed especially for layered double hydroxide (LDH), but little is known about how to promote the reconstruction toward desired surfaces for improved oxygen evolution reaction (OER). Here, surface reconstruction of NiFe LDH nanosheets is successfully induced to a higher degree via in situ sulfur doping than that by natural electrochemical activation. Theoretical calculations, operando Raman, and various ex situ characterizations reveal the S anion‐induced effect can lower the energy barrier and facilitate the phase transformation into highly active S‐doped oxyhydroxides. The generated S‐NixFeyOOH can optimize the intermediate adsorption and facilitate the OER kinetics. The reconstructed S‐oxyhydroxides catalyst presents superior OER activity and long‐term durability compared to undoped ones. This work provides a structure–composition–activity relationship during the in situ surface restructuring of NiFe LDH pre‐catalysts.

The in vitro and in vivo antibacterial activities of uniflorous honey from a medicinal plant, Scrophularia ningpoensis Hemsl., and characterization of its chemical profile with UPLC-MS/MS

Ethnopharmacological relevanceAccording to the Compendium of Materia Medica, honey has been used as a traditional medicine in treatment against mucositis, tinea, hemorrhoids and psoriasis. In complementary medicine, due to its significant antimicrobial activity, honey has been widely used as a remedy for skin wounds and gastrohelcosis for thousands of years. Aim of the studyThis study is aimed at exploring the antimicrobial activity and mechanisms of honey sourced from medicinal plants, and revealing the composition-activity relationship, to facilitate their complementary and alternative application in the therapy of bacterial infectious diseases. Materials and methodsEight kinds of medicinal plant-derived uniflorous honey, native to China, were gathered. Their antimicrobial activities were evaluated in vitro, and then in vivo with the systemically infected mouse model and the acute skin infection model. SYTOX uptake assay, scanning electron microscopy, DNA binding assay, and quantitative real-time PCR, were carried out to elucidate the antibacterial mechanisms. This was followed by an investigation of the componential profile with the UPLC-MS/MS technique. ResultsIt was found that Scrophularia ningpoensis Hemsl. (figwort) honey (S. ningpoensis honey) exhibited broad-spectrum and the strongest antibacterial potency (MICs of 7.81–125.00%, w/v), comparable to manuka honey. In the in vivo assays, S. ningpoensis honey significantly decreased the bacterial load of the muscles under the acute MRSA-infected skin wounds; the sera level of TNF-α in the S. aureus and P. aeruginosa-infected mice decreased by 45.38% and 51.75%, respectively, after the treatment of S. ningpoensis honey (125 mg/10 g). It was capable of killing bacteria through disrupting the cell membranes and the genomic DNA, as well as down-regulating the expression of genes associated with virulence, biofilm formation and invasion, including icaA, icaD, eno, sarA, agrA, sigB, fib and ebps in S. aureus, and lasI, lasR, rhlI, rhlR and algC in P. aeruginosa. Apart from H2O2, some other nonperoxide compounds such as adenosine, chavicol, 4-methylcatechol, trehalose, palmitoleic acid and salidroside, might play a vital role in the antibacterial properties of S. ningpoensis honey. ConclusionsThis is the first study to thoroughly investigate the antibacterial activity, mode of action, and componential profile of S. ningpoensis honey. It suggested that S. ningpoensis honey might be a potential supplement or substitute for manuka honey, for the prevention or treatment of bacterial infections. It will facilitate the precise application of medicinal plant-sourced honey, provide a new thread for the development of antibacterial drugs, and assist in the distinction of different kinds of honey.

Inhibitory effect of selected Indian honey on colon cancer cell growth by inducing apoptosis and targeting the β-catenin/Wnt pathway.

Colon cancer is the most prevalent cause of death from cancer across the globe. Although chemotherapy drugs are predominantly used, their toxicity always remains a cause of concern. As an alternative to synthetic drugs, natural compounds or nutraceuticals are comparatively less toxic. Honey is widely used across different cultures as an alternative form of medicine. It represents a prominent source of plant-phenolic compounds and there is demonstrable evidence of its anti-oxidant and anti-microbial activities. The aim of the present work was to investigate the anti-proliferative effect of some Indian honeys and analyze their mechanism of action in colon cancer. In order to establish the composition-activity relationship, we evaluated the bioactive components present in selected honey samples by GC-MS and HPLC analysis. Indian honey samples showed a significant inhibitory impact on cell growth by restricting cell proliferation, causing apoptosis, and restricting the cell cycle in the G2/M phase specifically for colon cancer cells. The apoptotic activities, as imparted by the honey samples, were established by Annexin V/PI staining, real-time PCR, and immunoblot analyses. The treated cells showed increased expressions of p53 and caspases 3, 8, and 9, thus indicating the involvement of both extrinsic and intrinsic apoptotic pathways. The honey samples were also found to inhibit the β-catenin/Wnt pathway. In the next phase of the study, the efficacy of these honey samples was evaluated in colon carcinoma induced SD-rats. Overall, these findings demonstrated that selected Indian honeys could be established as effective nutraceuticals for the prevention as well as cure of colon cancer.

Machine Learning Data Augmentation as a Tool to Enhance Quantitative Composition-Activity Relationships of Complex Mixtures. A New Application to Dissect the Role of Main Chemical Components in Bioactive Essential Oils.

Scientific investigation on essential oils composition and the related biological profile are continuously growing. Nevertheless, only a few studies have been performed on the relationships between chemical composition and biological data. Herein, the investigation of 61 assayed essential oils is reported focusing on their inhibition activity against Microsporum spp. including development of machine learning models with the aim of highlining the possible chemical components mainly related to the inhibitory potency. The application of machine learning and deep learning techniques for predictive and descriptive purposes have been applied successfully to many fields. Quantitative composition–activity relationships machine learning-based models were developed for the 61 essential oils tested as Microsporum spp. growth modulators. The models were built with in-house python scripts implementing data augmentation with the purpose of having a smoother flow between essential oils’ chemical compositions and biological data. High statistical coefficient values (Accuracy, Matthews correlation coefficient and F1 score) were obtained and model inspection permitted to detect possible specific roles related to some components of essential oils’ constituents. Robust machine learning models are far more useful tools to reveal data augmentation in comparison with raw data derived models. To the best of the authors knowledge this is the first report using data augmentation to highlight the role of complex mixture components, in particular a first application of these data will be for the development of ingredients in the dermo-cosmetic field investigating microbial species considering the urge for the use of natural preserving and acting antimicrobial agents.

Composition-Activity Relationships of Polysaccharides from Saccharina japonica in Regulating Gut Microbiota in Short-Term High-Fat Diet-Fed Mice.

Saccharina japonica polysaccharide could modulate gut microbiota composition; however, the composition-activity relationship remains unclear, thus restricting its application. In the current study, we investigated the impact of eight different S. japonica polysaccharide fractions on the gut microbiota after day 2 and day 14 treatments on high-fat diet (HFD) feeding mice. The results showed that a 2 day HFD dramatically altered gut microbiota composition, and the additional 12 day HFD further strengthened the gut microbiota dysbiosis in the HFD group. LjA-1 and LjA-3 could partially alleviate the dysbiosis of gut microbiota composition and significantly alter gut microbiota function. Multiple linear regression analysis revealed that the sulfate content and the molecular weight distributions were the main factors affecting the dominant gut bacterial genera. Our findings reveal that gut microbiota homeostasis could be disordered by HFD at day 2 and provide insights into the quantitative composition-activity relationships of polysaccharides in regulating gut microbiota.

Anti-inflammatory constituents in the root and rhizome of Polygonum cuspidatum by UPLC-PDA-QTOF/MS and lipopolysaccharide-activated RAW264.7 macrophages

The root and rhizome of Polygonum cuspidatum (Hu-Zhang) has been used for treatment of various inflammatory disorders in China. In our pervious study, we found that three fractions (HZE-30, HZE-60 and HZE-95) from the ethanol extract of Hu-Zhang (HZE) all could inhibit NO production, and HZE-60 shows the most potent anti-inflammatory activity. In order to understand the major contribution constituents of Hu-Zhang responsible for its anti-inflammatory effect, quantitative composition-activity relationship method was performed. Firstly, the constituents in HZE-60 were characterized using an ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) approach. Second, quantitative analyzed five major constituents identified in HZE-60 and compare the difference of five major constituents in HZE and three anti-inflammatory activity fractions. Finally, evaluated the anti-inflammatory effects of major constituents in lipopolysaccharide (LPS)-activated RAW264.7 macrophages. The results showed that a total of 31 compounds were identified from HZE-60, including 12 anthraquinones, 7 diphenylethenes, 9 phenols and 3 others. The contents of five major constituents (polydatin (6), resveratrol (7), emodin-1-O-β-d-glucoside (15), emodin-8-O-β-d-glucoside (21) and emodin (31)) were simultaneously determined by UPLC-PDA with good linearity (correlation coefficients > 0.9990) and satisfactory repeatability (RSD < 0.99 %), precision (RSD < 0.01 %), stability (RSD < 0.67 %) and recoveries (99.52 %–101.23 %, RSD < 0.91 %). All five major constituents could be detected in HZE and HZE-60 fraction, but only 6 was detected in HZE-30, and 31 in HZE-95. Moreover, 7, 15 and 21 exhibited significant anti-inflammatory activity via suppressing supernatant pro-inflammatory mediators, such as NO, tumor Necrosis Factor-α (TNF-α), interleukin-6 (IL-6) and monocyte chemotactic protein-1 (MCP-1). Therefore, we conclude that the bioactivity of HZE is the syngeneic effect of its constituents, and 7, 15 and 21 should make great contributions for the anti-inflammatory effect of Hu-Zhang. The findings define the anti-inflammatory chemical constituents of Hu-Zhang, which will benefit further investigation on its quality control and the mechanism of action.

Nitride or Oxynitride? Elucidating the Composition–Activity Relationships in Molybdenum Nitride Electrocatalysts for the Oxygen Reduction Reaction

Molybdenum nitride (Mo–N) catalysts have shown promising activity and stability for the oxygen reduction reaction (ORR) in acid. However, the effect of oxygen (O) incorporation (from synthesis, cat...

Chemical composition of Crithmum maritimum L. essential oil and hydrodistillation residual water by GC-MS and HPLC-DAD-MS/MS, and their biological activities

Aromatic and medicinal plants, such as those from the Apiaceae family, and their metabolites, namely essential oils are of great industrial interest and a source of biologically relevant compounds.Essential oils are the major resource obtained during the hydrodistillation of aromatic plants, however, this process also originates high amounts of residual water. Although this by-product is discarded, it is conceivable that this water may be rich in non-volatile compounds which possess interesting biological properties. Therefore, the aim of this work is to analyze the oil and the hydrodistillation residual water of Crithmum maritimum L. (sea fennel), a highly aromatic plant widely used in many European countries and highlight the bioactive potential of both products. High performance liquid chromatography-photodiode array detector-mass spectrometry (HPLC-DAD-MS/MS) analysis of the hydrodistillation residual water showed a profile rich in hydroxycinnamic acids and small amounts of flavone and flavonol glycosides. Chemical analysis of the essential oil by gas chromatography coupled with mass spectrometry (GC-–MS) has revealed that γ-terpinene (33.6 %), sabinene (32.0 %) and thymol methyl ether (15.7 %) are the major compounds.The antioxidant potential of the residual water was disclosed by the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and a composition-activity relationship was unveiled by thin layer chromatography (TLC). The anti-inflammatory potential was demonstrated by using an in vitro model of inflammation (lipopolysaccharide (LPS)-stimulated macrophages). Furthermore, the antifungal potential was evaluated by the capacity to inhibit two important virulence factors in Candida albicans.Our results show that the residual water have a promising antioxidant potential as measured by DPPH scavenging assay (IC50 of 650 ± 160 μg/mL). Chlorogenic acid and quercetin derivatives found in the hydrodistillation residual water are the mainly contributors for this activity. The essential oil of C. maritimum (3.125 μg/mL) decreases the production of nitric oxide in LPS-stimulated macrophages by 37 % without affecting cell viability. In addition, the essential oil has a strong effect on virulence factors of C. albicans through inhibiting the formation of the germ tube by more than 50 % at 30 μg/mL besides, it is able to inhibit biofilm formation by decreasing both the biomass and the cell viability.Summing up, the present work highlights that the essential oil of Crithmum maritimum and the non-volatile extract rich in hydroxycinnamic acids and flavonoid glycosides, obtained after the hydrodistillation process have important biological activities, thus endorsing the industrial exploitation of this plant.

Composition-dependent electrochemical activity of Ag-based alloy nanotubes for efficient nitrogen reduction under ambient conditions

The composition-activity relationship is highly desirable for electrocatalytic nitrogen reduction reaction (NRR) because it could guide the rational design of efficient NRR catalysts. In this work, the composition effect of Ag-based alloy nanotubes on electrocatalytic NRR activity is systematically investigated. It is found that, among AgAu nanotubes with atomic ratio from 8:1 to 1:2, Ag2Au1 alloy nanotubes achieve the largest enhancement for NRR catalytic activity. Specifically, the NH3 production rate and faradaic efficiency of Ag2Au1 nanotubes are 21.7 μg h−1 mgcat−1 and 3.8% at −0.30 V vs. RHE, respectively, which were 3.0 and 3.6 times higher than those of Ag nanowires. Compared with Ag2Pd1 and Ag2Pt1 nanotubes, Ag2Au1 hollow nanotubes also exhibit a better NRR catalytic activity. Theoretical calculation results indicate that the negative ion characteristic of Au atoms in the Ag2Au1 alloy is favorable for the adsorption and activation of N2. Moreover, Ag2Au1 nanotubes showed stable NH3 yield rate and faradaic efficiency up to 18 h, revealing its great potential for promising NRR electrocatalysis.

Evaluation of cellular antioxidant components of honeys using UPLC-MS/MS and HPLC-FLD based on the quantitative composition-activity relationship

Antioxidant molecules in honey contributed to various biological effects, but antioxidant components markers in honey are required to be investigated further. Phenolic compounds, flavonoids and free amino acids were analyzed using UPLC-MS/MS and HPLC-FLD from 39 honey samples, in which fennel honey was firstly investigated. Based on the quantitative composition-activity relationship, the cellular antioxidant activity (CAA) assay of various honeys is closely related with the interaction of some phenolic compounds (isoferulic acid, 3,4-dihydroxy benzoic acid, 4-hydroxy benzoic acid, chlorogenic acid, caffeic acid, gallic acid, cryptochlorogenic acid, p-coumaric acid, salicylic acid), flavonoids (isosakuranetin, sakuranetin, pinocembrin, vitexin, taxifolin, galangin, luteolin, chrysin) and free amino acids (Tyr, Gly, Ile, Glu, Val, Phe, Leu, Asp, His, Pro, Ala). The results would be beneficial for the understanding of the nutritional values, exploitation and utilization of honeys with different floral origins, further contributable to the market development and consumption choice of honey.

Synergetic quantitative composition-activity relationship between the aroma components and aroma quality of 8 famous green teas

This article identifies the aroma quality of eight different types and grades of famous green teas by E-nose combined with partial least squares discriminant analysis (PLSDA). Subsequently, in order to further explain the reasons for the differences in aroma quality, the background drift correction, multi-scale Gaussian smoothing and chromatographic retention time correction methods were employed to preprocess the chromatographic fingerprint of the famous green tea collected from GC-MS technology. Then, the pre-processed fingerprint and the famous green tea aroma score were analyzed to construct spectrum-activity relationship model by moving window partial least squares regression (MWPLSR). As a result, 21 kinds of latent characteristic aroma substances were screened out. Finally, the variable weighted least squares support vector (PSO-VWLS-SVM) was used to correlate the content of 21 kinds of latent characteristic aroma substances with the score for the aroma quality of different green tea. According to the contribution rate of each characteristic aroma substance to the score, a synergistic quantitative composition-activity relationship between aroma substances and the aroma quality of the famous green tea was successfully revealed. This method provided a new strategy for screening and quantitative analysis of characteristic aroma substances , as well their synergistic relationship in aroma quality of green tea.

Transition-Metal-Doped RuIr Bifunctional Nanocrystals for Overall Water Splitting in Acidic Environments.

The establishment of electrocatalysts with bifunctionality for efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic environments is necessary for the development of proton exchange membrane (PEM) water electrolyzers for the production of clean hydrogen fuel. RuIr alloy is considered to be a promising electrocatalyst because of its favorable OER performance and potential for HER. Here, the design of a bifunctional electrocatalyst with greatly boosted water-splitting performance from doping RuIr alloy nanocrystals with transition metals that modify electronic structure and binding strength of reaction intermediates is reported. Significantly, Co-RuIr results in small overpotentials of 235 mV for OER and 14 mV for HER (@ 10 mA cm-2 current density) in 0.1 m HClO4 media. Therefore a cell voltage of just 1.52 V is needed for overall water splitting to produce hydrogen and oxygen. More importantly, for a series of M-RuIr (M = Co, Ni, Fe), the catalytic activity dependence at fundamental level on the chemical/valence states is used to establish a novel composition-activity relationship. This permits new design principles for bifunctional electrocatalysts.

Unraveling the composition-activity relationship of Pt[sbnd]Ru binary alloy for hydrogen oxidation reaction in alkaline media

The research and development of hydrogen oxidation reaction catalysts in alkaline media is a prerequisite for the commercialization of alkaline polymer electrolyte fuel cell. PtRu bimetallic catalyst was found to be more active towards HOR than Pt in alkaline, but the composition-activity relationship of PtRu alloys is still lacking. Herein, a series of PtRu alloy planar electrodes with 14 different compositions were prepared in a high-throughput fashion using an improved magnetron sputtering method. The atomic ratio of Pt was controlled from 6.7% to 99.7% within the samples. The corresponding electro-catalytic activities towards the HOR in alkaline were systematically measured by rotating disc electrode method. A volcano-shape relationship between the HOR exchange current density and the Ru atomic fraction was revealed, and maximum activity was observed at ca. 55% content of Ru. The enhancement in electro-catalytic activity is attributed to a reduction in the electronic charge density of Pt upon Ru doping.