NO3 Radicals Research Articles

Fabrication and Electrochemical Evaluation of Organic Secondary Battery Capable of Charging and Discharging in Neutral Solution

There are attractive attentions on organic secondary batteries as new energy storage devices, in which organic compounds as electrode active materials supported on a porous carbon. Dilute sulfuric acid and organic solvents were used as electrolytes1,2). On the other hand, an organic electrolyte has a risk of ignition, and an acidic electrolyte is low safety when leaked.In this study, we newly fabricated an organic secondary battery that can be charged and discharged with a non-flammable, non-poisonous neutral aqueous solution, and evaluated its electrochemical performance.4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl-benzoate (TEMPO-benzoate) was used as the cathode active material, and 9,10-anthraquinone (AQ) was used as the anode active material. Both active materials are hydrophobic and expected to overcome the problem of elution of the active material into the electrolyte.Firstly, carbon cloth was immersed in a slurry of acetylene black and polyvinylidene fluoride (PVdF) ultrasonically dispersed in N-methyl-2-pyrrolidone (NMP) and dried at 60 ° C for 48 hours. Next, each active material solution was dropped, dried under reduced pressure for 4 hours to adsorb each active material, and a porous carbon electrode was produced. For single electrode evaluation, cyclic voltammetry was performed at a scanning speed of 10 mV s-1. The as-fabricated electrodes were used as the working electrode, a platinum mesh was used as the counter electrode, a saturated KCl/Ag/AgCl electrode (SSE) was used as the reference electrode, and a 1 mol/dm3 KCl aqueous solution was used as the electrolyte. An organic secondary battery was fabricated using the as-fabricated electrode, and electrochemical evaluation was performed by a charge and discharge test using a reference electrode. A cellophane was used for the separator.Figure 1 (A) shows the reaction mechanism of the active materials of both electrodes used in this study. Figure 1 (B) and (C) show the cyclic voltammograms of AQ and TEMPO-benzoate. It was found that AQ showed an anodic peak near -0.65 V vs. SSE and a cathodic peak near -0.8 V vs. SSE (Fig. 1(B)). The anodic current and cathodic current is related to the two-electron transfer reaction between quinone and hydroquinone shown on the left side of Fig.1 (A). TEMPO-benzoate showed an anodic peak near 0.85 V vs. SSE and a cathodic peak near 0.65 V vs. SSE (Fig. 1(C)) due to the one-electron transfer reaction between the NO radical and the NO cation on TEMPO-benzoate shown on the right side of Fig. 1 (A). The peak appeared near 1.1 V vs. SSE in Fig. 1 (C) is considered to be due to chlorine gas generation on the electrode surface by chloride ions in the electrolyte.Figure1 (D) shows the results of a charge and discharge test performed by applying a constant current of 820 mA to an organic secondary battery. The cut-off voltage were 2 V and 0.4 V, respectively. A large irreversible capacity appeared during the first charge. The potentials of the two electrodes during charging and discharging using the reference electrode suggested that reduction of dissolved oxygen in the negative electrode and oxygen in the porous carbon pores and side reactions were caused. On the other hand, it was confirmed that charge and discharge was performed stably repeatedly after the first discharge. We also tried to improve cycling characteristics by suppressing irreversible capacity by performing thorough degassing of porous carbon and degassing of electrolyte, and assembling cells in an inert gas atmosphere. References 1) T. Tomai et al., Scientific reports, 4, 3591 (2014).2) B. Huskinson et al., Nature, 505, 195-198 (2014). Acknowledgments This work was partially supported by JST-ASTEP Grant Number JPMJTS1513, JSPS Grant Number 17H02162 and Private University Research Branding Project (2017-2019) from Ministry of Education, Culture, Sports, Science and Technology, and Tokyo University of Science Grant for President's Research Promotion． Figure 1

Theoretical Study on the Mechanism for the Formation of Nitro Compounds in Red Oil

The mechanisms involved in reactions between methane, n-hexane, n-butanol, cyclohexane, and nitric acid were explored by density functional theory calculations. All the calculations in gas phase and n-tributyl phosphate (TBP) solvent were performed at the B3LYP/6–311++G ∗ ∗ and CCSD(T)/6–311++G ∗ ∗ levels of theory. The results showed that TBP has an important effect on the reactions between nitric acid and alkanes or butanol. The reactions were considered as that the radicals (·NO2 and ·NO3 radicals are formed via the HNO3 decomposition under irradiation) initiate the H-atom depletion of the reactants (R), and the produced radicals in red oil combine with ·NO2 radical to form the nitro compounds spontaneously. The rate constants of reactions R + ·NO2 and R + ·NO3 differ substantially, the rate constants of the latter being much larger than those of the former. In the reactions of R + ·NO3, the transition states and products are 20 kJ/mol and 100 kJ/mol or more stable than the reactants, respectively, but the reactions of R + ·NO2 need to overcome energy barriers over 25 kJ/mol. The formations of products mainly depend on the reactions of R + ·NO3. For the same type of alkanes (either chain or cyclic ones), the lower the relative stabilities of carbon-centered radicals are, the more reactive the alkanes are. Cyclohexane is the most competitive species, followed by n-butanol, n-alkanes, and methane which are the least competitive.

Polysaccharides from dandelion (Taraxacum mongolicum) leaves: Insights into innovative drying techniques on their structural characteristics and biological activities

The aim of this study was to well understand the impacts of innovative drying techniques (radio frequency drying and microwave drying) and traditional drying techniques (vacuum drying, freezing drying, and hot air drying) on the structural characteristics and bioactivities of polysaccharides from dandelion leaves (DLPs). Five different DLPs were obtained from dandelion leaves dried by abovementioned drying techniques. Results showed that the structural characteristics and bioactivities of DLPs varied with different drying techniques. The molecular weights, apparent viscosities, molar ratios of constituent monosaccharide, contents of uronic acids, and contents of bonded polyphenolics in DLPs obtained by different drying techniques had noticeable variations, while the types of constituent monosaccharides and the major glycosidic linkages in DLPs were similar. In addition, results showed that DLPs, especially DLP-RF obtained by the radio frequency drying, exhibited remarkable antioxidant activities (ABTS, DPPH, and NO radical scavenging activities), excellent in vitro antiglycation activity, and obvious in vitro inhibitory activity on α-glucosidase. Results from this study suggest that the radio frequency drying can be used as a potential drying technique before extracting DLPs for applications in the functional food and medicine industries.

A family of 2p-3d complexes based on 4,5-dimethyltriazole nitronyl nitroxide radical: synthesis, structure, and magnetic properties

Three 2p-3d complexes were successfully synthesized by using 4,5-dimethyltriazole nitronyl nitroxide radical. All of the complexes with the same formula of [M(hfac)2(4,5-di-Me-3-NIT-trz)2] [M = Co(II) 1, Ni(II) 2, Cu(II) 3; 4,5-di-Me-3-NIT-trz = 2-[3-(4,5-dimethyl-l,2,4-triazolyl)]-4,4,5,5-tetramethylimida-zoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetone] are characterized by X-ray analysis, and their magnetic properties were studied in detail. The metal ions in 1–3 are all in distorted octahedral configuration with four oxygen atoms from two bidentate hfac– ligands, and two triazole N atoms from two different 4,5-di-Me-3-NIT-trz ligands. The magnetic behaviors for 1–3 indicate that the metal ions and the radicals are antiferromagnetically coupled (JCo-rad = −7.11 cm−1, for 1; JNi-rad = −1.63 cm−1, for 2; JCu-rad = −8.71 cm−1, for 3). In addition, ferromagnetic coupling exists between the uncoordinated NO radicals in complex 1, while the magnetic reactions Jrad-rad are antiferromagnetic in complexes 2–3.

Measurement of nitrogen dioxide and nitric oxide densities by using CEAS (cavity‐enhanced absorption spectroscopy) in nonthermal atmospheric pressure air plasma

AbstractNonthermal atmospheric pressure plasmas are widely used in biomedicine and agriculture. Currently, radical density is used as an important parameter for the development of plasma biomedicine and agriculture. Especially, nitrogen dioxide (NO2) and nitric oxide (NO) radicals are significant species in these applications. These could be measured by using the cavity‐enhanced absorption spectroscopy (CEAS) technique. For the NO2 and NO radical density measurement, we used a visible LED (light‐emitting diode) of 660 nm and a mid‐infrared LD (laser diode) of 5238.6 nm, respectively. Radical densities can be calculated with the transmission ratio using Beer–Lambert law, which is obtained by the absorbed amount of laser intensity passed through the gas from the plasma jet in an optical cavity of CEAS.

Vertically increased NO3 radical in the nocturnal boundary layer

In the nocturnal boundary layer, nitrate radical (NO3) has an important contribution to atmospheric chemistry through oxidation of nitrogen oxides and hydrocarbons. Vertical distributions of NO2, O3 and NO3 were measured by four differential optical absorption spectroscopy instruments at meteorological tower in Beijing from June 1 to July 22, 2019. The results show the mean diurnal variations of NO2, O3, and NO3 display a single peak (up to 65.0 ppbv, 196.8 ppbv and 317.5 pptv, respectively) in time. O3 and NO3 mixing ratios generally increased against heights, which is opposite to NO2, suggesting the contribution of O3 to NO3 production at higher altitude. According to the correlation coefficients between NO3 production rates (PNO3) and NO2 or O3 levels, PNO3 was sensitive to NO2 mixing ratio at higher altitude but to O3 near the ground. Averaged NO3 lifetimes (τNO3) of lowest, middle, upper and highest layer intervals were 104, 118, 164 and 213 s, respectively, which indicates τNO3 increase against height and explains why NO3 mixing ratios are larger at higher altitude to some extent. Main control factors of NO3 removal changed from gas-phase reactions to N2O5 hydrolysis with height increase. When relative humidity (RH) exceeded 70% or PM2.5 level exceeded 50 μg·m−3, τNO3 was almost less than 300 s with mixing ratio lower than 70 pptv. The clear negative dependence of τNO3 on RH and PM2.5 reveals the influencing factors on indirect loss. Under polluted conditions, vertical profiles of NO2, O3 and NO3 varied drastically. Stable atmosphere (low nocturnal boundary layer height and thermal inversion), RH level and RH gradient are the main reason for the evident difference in NO3 gradient. Vertically increased NO3 radicals may imply the formation of nitrate aerosols and further increase the nitrate content in high- altitude particulate matter.

The Reaction Path of Product Release in NO Detoxification at the Active Site of Truncated Hemoglobin N in MCSCF Approach

The Multi-Configurational Self-Consistent Field approach with the geometry optimization was applied to the calculation of electronic properties of active site of heme core of truncated hemoglobin N, with the inclusion of [ONOO] functional group and two water molecules. The localized molecular orbitals are employed as a starting set. Two subspaces of full interaction have been used by the construction of MCSCF wavefunction. The first one includes 3d orbitals of iron atom, and the second contains bonding and antibonding molecular orbitals of peroxynitrite with one unshared electronic pair of the O2 fragment. The reaction is characterized by two transition states; the products are nitrate anion and one unbound water molecule. There arise an evidence of NO2 and NO radicals as the reaction products.

Impact of Ocimum Tenuiflorum Mediated Green Synthesis of Silver Nanoparticles on In-Vitro Antioxidant and Antibacterial Activities

The leaf extract of O. tenuiflorum was used to synthesize silver nanoparticles (AgNPs) and evaluated for its antioxidant and antibacterial properties. The silver nanoparticle was characterized using the UV-Vis spectrophotometer, SEM, FTIR, and XRD. The total phenolic and total flavonoid contents were determined for both leaf extract and synthesized silver nanoparticles. Antioxidant activities before and after synthesis of silver nanoparticles was assessed by DPPH, ABTS, iron chelating, and NO radical scavenging methods. The antibacterial activity of the leaf extract and AgNP were tested against Escherichia coli and Staphylococcus aureus. Statistical analysis was carried out to establish possible relations between the antioxidant, antibacterial and antioxidant activities. The formation of a dark brown solution mixture confirms the formation of silver nanoparticles at a wavelength of 450 nm. The AgNPs synthesized were spherical, with the size between 14 to 33 nm. Functional groups such as alcohol, aldehyde, nitrile, primary amines, carbonyl, and aromatic groups were confirmed by FTIR and XRD. Total phenol was higher in leaf extract, while total flavonoids were higher in the AgNps. Silver nanoparticles exhibited strong NO scavenging activity while leaf extract showed better ABTS scavenging activity. Silver nanoparticles inhibited E. coli better compared to S. aureus bacteria. It can be coined that the leaf extract of Ocimum tenuiflorum mediated the green synthesis of silver nanoparticles and possess strong antioxidant and antibacterial potentials that can find application in various biomedical areas.

EPR study of NO radicals encased in modified open C60 fullerenes.

Using pulsed electron paramagnetic resonance (EPR) techniques, the low-temperature magnetic properties of the NO radical being confined in two different modified open -derived cages are determined. It is found that the smallest principal value , being assigned to the axis of the radical, deviates strongly from the free electron value. This behaviour results from partial compensation of the spin and orbital contributions to the value. The measured values in the range of 0.7 yield information about the deviation of the locking potential for the encaged NO from axial symmetry. The estimated 17 meV asymmetry is quite small compared to the situation found for the same radical in polycrystalline or amorphous matrices ranging from 300 to 500 meV. The analysis of the temperature dependence of spin relaxation times resulted in an activation temperature of about 3 K, assigned to temperature-activated motion of the NO within the modified open -derived cages with coupled rotational and translational degrees of freedom in a complicated three-dimensional locking potential.

Unusual Nitrene Oxidation Product Formation by Metathesis Involving the Dioxygen O-O and Borylnitrene B-N Bonds.

The reaction of dioxygen with nitrenes can have significant energy barriers, although both reactants are triplet diradicals and the formation of nitroso‐O‐oxides is spin‐allowed. By means of matrix‐isolation infrared spectroscopy in solid argon, nitrogen, and neon, and through high‐level computational quantum chemistry, it is shown herein that a 3‐nitreno‐1,3,2‐benzodioxaborole CatBN (Cat=catecholato) reacts with dioxygen under cryogenic conditions thermally at temperatures as low as 7 K to produce two distinct products, an anti‐nitroso‐O‐oxide and a nitritoborane CatBONO. The computed barriers for the formation of nitroso‐O‐oxide isomers are very low. Whereas anti‐nitroso‐O‐oxide is kinetically trapped, its bisected isomer has a very low barrier for metathesis, yielding the CatBO+NO radicals in a strongly exothermic reaction; these radicals can combine under matrix‐isolation conditions to give nitritoborane CatBONO. The trapped isomer, anti‐nitroso‐O‐oxide, can form the nitritoborane CatBONO only after photoexcitation, possibly involving isomerization to the bisected isomer of anti‐nitroso‐O‐oxide.

Solvate of 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-Hexaazaisowurtzitane (CL-20) with both N2 O4 and Stable NO2 Free Radical.

A new solvate of a powerful explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and liquid oxidizer N2 O4 has been synthesized. When stored at room temperature, the white crystals turn yellowish brown, which indicates partial dissociation of N2 O4 with the formation of a stable NO2 free radical, which is confirmed by ESR spectroscopy. The resulting solvate was analyzed by powder X-ray diffraction, IR-spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The vapor pressure of NO2 above the solvate crystals is similar to the pressure above common hydrates. The presence of the NO2 radical does not affect the thermal stability of CL-20. However, under closed conditions, NO2 increases the rate of the autocatalytic decomposition reaction. The kinetics of this reaction at the surface temperature determine the burning rate of the solvate. The novel solvate has a high density (1.98 g cm-3 ), a high predicted detonation velocity and pressure, and sensitivity to impact slightly higher to that of ϵ-CL-20.

국내 대류권 광화학 오존 연구의 현황과 방향

Ozone is a critical chemical species for sustaining natural oxidizing power of atmosphere, as it is the most abundant oxidant species, as well as the precursor of most strong oxidants, such as OH and NO₃ radicals in the troposphere. Although it plays an important role in reducing lifetimes of various pollutants in troposphere, it is also regarded as a criteria pollutant due to its adverse impact on human and ecological health. Long-term observations showed significant and rapidly increasing tends of tropospheric ozone in Korea. Ozone is the fast-rising public concern in air quality next to traditional PM pollution. This review summarizes the studies from the past 20 years associated with photochemical ozone in Korea, covering issues of long-term ozone trends analysis, its precursor emission inventories, biogenic VOCs emission, impact on the ecosystem, background ozone and long-range transport, health impacts, climate feedback, aerosol surface effects for HO₂ heterogeneous reaction and radiation budget, radicals budgets and their implications. Considering the current status of scientific findings, advance of knowledge, and challenge of recent ozone studies, this review focuses on delivering future directions of ozone studies in Korea. Present recommendations for the future ozone R&D include: 1) continuous promotion of basic science for solving fundamental aspects of ozone productions and transport, 2) strengthening specifically the regional studies for ozone unattained areas, 3) developing collaborative implementation plan for multi-ministerial R&D platforms, 4) extension and outreach of international research collaboration, including long-term intensive field campaigns, 5) multipollutant approach and partnership with PM studies for practical and effective framework of R&D strategies and capabilities with limited resources.

Experimental and numerical investigation of the promoting effect of a cetane booster in a low-octane gasoline fuel in a rapid compression machine: A study of 2-ethylhexyl nitrate

Modern societies require cleaner and more efficient internal combustion engines. Low-temperature combustion (LTC) has been proved to be a good step toward this goal. This study aims at investigating the promoting effect of a cetane booster additive named 2-ethylhexyl nitrate (EHN) on the reactivity of a low-octane gasoline at LTC-relevant conditions. Rapid compression machine experiments were conducted at 10 bar, from 675 to 960 K for stoichiometric mixtures. The neat fuel was a mixture of toluene and n-heptane whose research octane number is 84. The doping levels of the additive were set at 0.1 and 1% molar basis. At the experimental conditions, it is found that EHN provides a promoting effect on the surrogate reactivity over all the whole temperature range. This effect increases with EHN doping levels. The negative temperature coefficient (NTC) behavior of the surrogate fuel is mitigated by the presence of the additive. The EHN reactivity promoting effect is lowest around 710 K and then increases with temperature. Under some conditions, heat releases are observed during the compression process. The chemical reactivity of the fuel gas mixture during the piston movement has to be considered to get reliable simulations. Kinetic modeling works show a good agreement with experiments. The model of this study reproduces properly the EHN promoting effect over the whole range of investigated temperatures and doping levels. Numerical analyses were conducted. EHN can totally decompose during the compression process resulting in heat releases. EHN is less effective at low Tc (< 800 K) at lean condition than at stoichiometric condition. It is found that the EHN effect links to the OH radical formation and the NO2NO loop. The reactions between NO and n-heptyl peroxy radicals are found to be the main reason for the EHN effect in NTC region of the surrogate fuel oxidation.

Catalytic Mechanism of Aromatic Nitration by Cytochrome P450 TxtE: Involvement of a Ferric-Peroxynitrite Intermediate

The cytochromes P450 are heme-dependent enzymes that catalyze many vital reaction processes in the human body related to biodegradation and biosynthesis. They typically act as mono-oxygenases; however, the recently discovered P450 subfamily TxtE utilizes O2 and NO to nitrate aromatic substrates such as L-tryptophan. A direct and selective aromatic nitration reaction may be useful in biotechnology for the synthesis of drugs or small molecules. Details of the catalytic mechanism are unknown, and it has been suggested that the reaction should proceed through either an iron(III)-superoxo or an iron(II)-nitrosyl intermediate. To resolve this controversy, we used stopped-flow kinetics to provide evidence for a catalytic cycle where dioxygen binds prior to NO to generate an active iron(III)-peroxynitrite species that is able to nitrate l-Trp efficiently. We show that the rate of binding of O2 is faster than that of NO and also leads to l-Trp nitration, while little evidence of product formation is observed from the iron(II)-nitrosyl complex. To support the experimental studies, we performed density functional theory studies on large active site cluster models. The studies suggest a mechanism involving an iron(III)-peroxynitrite that splits homolytically to form an iron(IV)-oxo heme (Compound II) and a free NO2 radical via a small free energy of activation. The latter activates the substrate on the aromatic ring, while compound II picks up the ipso-hydrogen to form the product. The calculations give small reaction barriers for most steps in the catalytic cycle and, therefore, predict fast product formation from the iron(III)-peroxynitrite complex. These findings provide the first detailed insight into the mechanism of nitration by a member of the TxtE subfamily and highlight how the enzyme facilitates this novel reaction chemistry.

Correlations in rotational energy transfer for NO-D2 inelastic collisions.

We present a combined experimental and theoretical study of state-to-state inelastic collisions between NO (X 2Π1/2, j = 1/2, f) radicals and D2 (j = 0, 1, 2, 3) molecules at collision energies of 100 cm-1 and 750 cm-1. Using the combination of Stark deceleration and velocity map imaging, we fully resolve pair-correlated excitations in the scattered molecules. Both spin-orbit conserving and spin-orbit changing transitions in the NO radical are measured, while the coincident rotational excitation (j = 0 → j = 2) and rotational de-excitation (j = 2 → j = 0 and j = 3 → j = 1) in D2 are observed. De-excitation of D2 shows a strong dependence on the spin-orbit excitation of NO. We observe translation-to-rotation energy transfer as well as direct rotation-to-rotation energy transfer at the lowest collision energy probed. The experimental results are in good agreement with cross sections obtained from quantum coupled-channels calculations based on recent NO-D2 potential energy surfaces. The observed trends in the correlated scattering cross sections are understood in terms of the NO-D2 quadrupole-quadrupole interaction.

Trace pollutant fluctuations observed in Calicut city, India, during the annular solar eclipse on 26 December 2019

Atmospheric boundary layer perturbations were monitored during an annular solar eclipse event on December 26, 2019 to understand its impact on the meteorological parameters (temperature, relative humidity, wind speed, and wind direction) and trace gas concentrations (O3, NO, NO2, NH3, CO, and HONO) at Calicut (11.24° N, 75.78° E), a tropical city along the coastal belt of Arabian Sea in the southwest coast of Indian Subcontinent. The solar eclipse started at 8:05 IST (5.5 h ahead of UTC), reached to a maximum coverage of 93.28% at 09:27 IST and ends at 11:07 IST. Eclipse day data were compared with the nearby days' records from this site. The rapid fall in the irradiance caused cooling of the surface air by ~0.7 °C and weakened the wind speed, whereas the relative humidity, as expected, was increased by 5.1%. A gradual decrease in the surface O3 along with the reduction in solar irradiance was observed during the eclipse, due to the decreased efficiency in the photochemical formation of ozone. There was a decrease in mixing ratios of NO2 during the eclipse period, which was a result of the fall in ozone concentrations. No significant variation was observed in HONO levels, whereas variations in concentrations of NO and NH3 have followed the night time chemistry. The NO3 radical mixing ratios were below the detection limit during the eclipse event.

Metal‐Free Oxidative [5+1] Cyclization of 1,5‐Enynes for the Synthesis of Pyrazine 1‐Oxide

AbstractA chemo‐selective nitrosylation of 1,5‐enynes via a sequence of NO radical incorporation and intramolecular radical cyclization was reported. The formation of two C−N bonds and one C−O bond make this [5+1] cycloaddition reaction an efficient approach to synthesize pyrazine 1‐oxides in moderate to good yields. Metal‐free, short reaction time and mild conditions render this strategy more practical, eco‐friendly and convenient. Synthetic utility of this protocol is highlighted by scaffolds diversification.magnified image

Secondary organic aerosol formation from the gas-phase reaction of guaiacol (2-methoxyphenol) with NO3 radicals

Abstract Methoxyphenols are oxygenated aromatic compounds emitted by wood combustion (consequently to the pyrolysis of lignin). The atmospheric reaction of nitrate radical (NO3) with guaiacol (2-methoxyphenol), one of the principal representatives of this class of compounds has been investigated in the dark at (294 ± 2) K, atmospheric pressure and low relative humidity (RH

Comparative study of the phenolic profile, antioxidant properties, and inhibitory effects of Moringa (Moringa oleifera Lam.) and Almond (Terminalia catappa Linn.) leaves on acetylcholinesterase and monoamine oxidase activities in the head region of Fruitfly (Drosophila melanogaster Meigen) in vitro.

Moringa and Almond are medicinal plants used traditionally as food and medicine to prevent and/or treat a wide array of metabolic and neurodegenerative diseases, however, Almond leaf is underutilized. Therefore, this study investigated and compared the polyphenol constituents, antioxidant capacities, and neurochemical indices of the aqueous extracts of Moringa and Almond leaves in fruitfly head tissue homogenate in vitro. The polyphenols were evaluated by characterization using HPLC-DAD, antioxidant properties were assessed through extracts ability to inhibit ABTS, DPPH, OH, and NO radicals, reduce Fe3+ and MDA, and chelate Fe2+ . The neurochemical indices were evaluated through AChE and MAO inhibitory activities. Almond leaf had significant (p<.05) higher polyphenols and antioxidant properties. However, Moringa leaf had significant (p<.05) higher AChE inhibition and no significant (p<.05) difference was obtained in MAO inhibitory activities. Thus, Almond leaf might be more effective in managing diseases related with oxidative stress and neurodegeneration. PRACTICAL APPLICATIONS: This present study has shown that Almond leaf might offer better health promotion due to its higher phenolic constituents and antioxidant activities when compared with Moringa leaf, however, both Moringa and Almond leaves could be taken as functional foods to alleviate the symptoms of oxidative stress and neurodegenerative diseases.

Green synthesis of Ag@Au bimetallic composite nanoparticles using a polysaccharide extracted from Ramaria botrytis mushroom and performance in catalytic reduction of 4-nitrophenol and antioxidant, antibacterial activity

An eco-friendly synthetic procedure was used to prepare silver-gold bimetallic composite nanoparticles (Ag@AuCNPs)by using a mixture of aqueous solutions of silver nitrate, chloroauric acid and Ramaria botrytis mushroom polysaccharide (RBPS) at 80−85 °C in water medium. The synthesized Ag@AuCNPs were characterised by using UV–vis spectroscopy, X-ray diffraction (XRD) analysis, high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDAX) and X-ray photoelectron spectroscopy (XPS). The synthesized Ag@AuCNPs showed potential antioxidant activities towards DPPH radical, NO radical, hydrogen peroxide scavenging assays and ferric ion reducing assay. Besides that Ag@AuCNPs showed powerful antibacterial activity towards a gram negative bacterium Pseudo monasaeruginosa (MTCC No.-424). Catalytic activity of Ag@AuCNPs was tested by considering, 4-nitrophenol reduction as a model reaction in aqueous medium at room temperature using UV–vis spectroscopy. The catalyst concentration was varied to find out the optimum conditions. The rate constant was evaluated by using pseudo first order kinetic model. The prepared nanoparticles showed a good catalyst towards p-nitrophenol reduction, a good antioxidant and a moderate antibacterial agent towards Pseudomonas aeruginosa. These observations signify that such green method opens up new avenues in nano biotechnology for the synthesis of nanoparticles with intensive industrial and biomedical applications.