NO3 Radicals Research Articles

Nyctanthes arbortristis: In Vitro Efficacy Of Anti-Oxidant Potential And Cytotoxicity Study Of Bark Extracts On Sw982 Rheumatoid Arthritis Cell Line Followed By Phytochemical Profiling By GCMS

Nyctanthes arbortristis, commonly known as the night-jasmine, is a plant rich in bioactive compounds with potential therapeutic benefits. This study aimed to evaluate the antioxidant properties and cytotoxic effects of Nyctanthes arbortristis bark extracts on SW982 rheumatoid arthritis cell line in vitro. Sequential solvent extraction method was employed to obtain extracts with varying polarities. The antioxidant potential of the extracts was assessed using DPPH, ABTS, NO, and H2O2 radical scavenging assays and total phenolic and flavonoid content determination. Cytotoxicity was evaluated using MTT assay on SW982 cells. Results revealed that the bark extracts exhibited significant antioxidant activity, with the methanol extract showing the highest radical scavenging activity, total phenolic content and total flavonoids contents. Furthermore, the bark extracts demonstrated concentration-dependent cytotoxic effects on SW982 cells, with the ethyl acetate extract exhibiting the most potent cytotoxicity. These findings suggest that Nyctanthes arbortristis bark extracts possess substantial antioxidant potential and cytotoxic effects against SW982 rheumatoid arthritis cells, indicating their potential as therapeutic agents in the management of rheumatoid arthritis. Further investigations are warranted to elucidate the underlying mechanisms and evaluate their efficacy in vivo.

Trifunctionalization of CC bonds in vinyl azides to access densely functionalized phenanthridines enabled by the NCS/AgNO2 system.

An unprecedented trifunctionalization of CC bonds in 2-(1-azidovinyl)-1,1'-biphenyls has been successfully achieved using the NCS/AgNO2 system, leading to the preparation of 6-(dichloro(nitro)methyl)phenanthridines in moderate to good yields. In this process, the NCS/AgNO2 system serves as a NO2 radical initiator as well as a chloro group source. The present protocol is a rare example of the selective construction of densely functionalized phenanthridine derivatives in a one-pot manner.

2500 vibronic eigenstates of the NO3 radical.

The nitrate radical NO3 plays an important role in atmospheric chemistry, yet many aspects of its coupled and anharmonic vibronic structure remain elusive. Here, using an accurate, coupled full-dimensional diabatic potential that includes five electronic states, we revisit the vibronic spectrum associated with the electronic state. Using recently developed tensor network state methods, we are able to compute more than 2500 vibronic states, thereby increasing the number of computed full-dimensional states by a factor of 50, compared to previous work. While we obtain good agreement with experiment for most of the assigned vibronic levels, for several others, we observe striking disagreement. Further, for the antisymmetric bending motion we find remarkably large symmetry-induced level splittings that are larger than the zero-order reference. We discuss non-negligible nonadiabatic effects and show that the Born-Oppenheimer approximation leads to significant errors in the spectrum.

Structure and nitric oxide formation in laminar diffusion flames of ammonia–hydrogen and air

In this work, we present an investigation of the structure and formation of nitrogen oxides (NOx) in an axisymmetric laminar diffusion flame in which an ammonia–hydrogen fuel stream is surrounded by co-flowing air. Green ammonia, produced using renewable energy, is a promising carbon-free fuel for replacing hydrocarbon fuels over a diverse range of combustion applications. A key challenge for ammonia combustion is to understand the kinetics of nitrogen oxide formation for designing low-NOx combustion systems. In this experimental study, ammonia fuel is blended with hydrogen to increase fuel reactivity, with a fuel composition range of 15%–100% hydrogen. NOx emissions and fuel slip are measured by downstream sampling of NO, NO2, N2O and NH3 with a Fourier Transform Infrared (FTIR) gas analyzer. Flame structure is visualized by planar laser-induced fluorescence (LIF) for NO, NH, and OH radicals, as well as OH* by filtered chemiluminescence. Species concentration profiles are compared to predictions from 2-dimensional axisymmetric numerical models of the laminar flame using recent kinetic mechanisms developed for ammonia combustion. No measurable ammonia slip was recorded for any fuel composition, in agreement with model predictions. Good agreement between predictions and measurements was obtained for exhaust nitrogen oxide concentrations and for in-flame radical profiles, although larger variation and deviations are observed for predictions of NO2 and N2O than for NO. Numerical predictions for spatial distribution of flame radicals and flame liftoff height also showed good agreement with LIF and chemiluminescence measurements. For high fuel hydrogen content, the measured NH and NO profiles are shifted inward toward the fuel outlet, away from the peak temperature contour. Reaction path analysis is used to illustrate the important contributions to NO creation and destruction, including the differing role of key reaction pathways with varying fuel hydrogen content.

Uptake and reactivity of NO2 on the hydroxylated silica surface: A source of reactive oxygen species

We report state-of-the-art first-principles molecular dynamics results on the heterogeneous chemical uptake of NO2, a major anthropogenic pollutant, on the dry and wet hydroxylated surface of α-quartz, which is a significant component of silica-based catalysts and atmospheric dust aerosols. Our investigation spotlights an unexpected chemical pathway by which NO2 (i) can be adsorbed as HONO by deprotonation of interfacial silanols (i.e., –Si–OH group) on silica, (ii) can be barrierless converted to nitric acid, and (iii) can finally dissociated to surface bounded NO and hydroxyl gas phase radicals. This chemical pathway does not invoke any previously experimentally postulated NO2 dimerization, dimerization that is less likely to occur at low NO2 concentrations. Moreover, water significantly catalyzes the HONO formation and the dissociation of nitric acid into surface-bounded NO and OH radicals, while visible light adsorption can further promote these chemical transformations. This work highlights how water-restricted solvation regimes on common mineral substrates are likely to be a source of reactive oxygen species, and it offers a theoretical framework for further and desirable experimental efforts, aiming to better constrain trace gases/mineral interactions at different relative humidity conditions.

Comprehensive Structural and Electronic Properties of 2-Azaadamantane N-Oxyl Derivatives Correlated with Their Catalytic Ability.

Herein, a comprehensive kinetic study is performed to compare the catalytic efficiency of 2-azaadamantane N-oxyl (AZADO) derivatives with that of 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) used as radical catalysts in the aerobic oxidation of l-menthol. Furthermore, the correlation between the catalytic activity and structural/electronic parameters of AZADOs and TEMPO is elucidated. The reaction rate constants achieved with several AZADO derivatives exhibit moderate relationships with spectroscopic parameters, such as the hyperfine coupling constant of the N atom (AN) and NO stretching vibration frequency (νNO) observed in electron spin resonance and infrared spectra, respectively. The planarity C-(NO)-C angle (φ) at the N atom, determined by density functional theory (DFT) calculations, also strongly correlates with the AN and νNO. Moreover, the bond order of NO, which strongly depends on the structural and electronic properties of NO radicals, correlates with radical activity; thus, the radical activity can be predicted by DFT calculations, thereby accelerating the synthesis of new AZADO derivatives without requiring alcohol oxidation experiments.

Products and yields for the NO3 radical initiated atmospheric degradation of 2-methylfuran (2-MF, CH3–C4H3O)

Furans represent a group of oxygenated, heterocyclic, organic compounds that are emitted during biomass burning (BB). Notably, these compounds undergo rapid oxidation, a process observed both during the day and at night. Methylated furanoids comprise a large fraction of total furan emissions. Recent kinetic studies suggest that the NO3 initiated degradation of methylated furans is the dominant reaction pathway during nighttime, and with significant contribution on daytime. The aim of this study is to investigate the degradation products and the reaction mechanism of 2-methylfuran (2-MF) reaction with NO3 radicals using two atmospheric simulation chambers: CHARME (Chamber for the Atmospheric Reactivity and the Metrology of the Environment, Dunkerque, France) and THALAMOS (Thermally Regulated Atmospheric Simulation Chamber, Douai, France). All experiments were carried out at ambient temperature, (294 ± 2) K and atmospheric pressure (760 Torr, zero air). Oxidation products were qualitatively and quantitatively characterized using multiple, complementary detection techniques. Gas phase major and minor products were detected via offline GC-EI-MS (Gas chromatography - Electronic Impact - Mass Spectrometry) after trapping the gas-phase mixture on different adsorption media. PTR-ToF-MS (Proton Transfer Mass Reaction – Time of Flight – Mass Spectrometer, CHARME) and SIFT-MS (Selected Ion Flow Tube Mass Spectrometry, THALAMOS) were used on-line to monitor reactants and major products and to determine the end-product yields. 4-Oxo-2-pentenal (H(O)CCHCHC(O)CH3), and 2(5H)-furanone, 5-methyl, 5-nitrooxy ((CH3)C(ONO2)(C4H2O2)) were detected as major products with yields (62 ± 15) % and (26 ± 3) %, respectively. In-situ FTIR (Fourier Transform Infrared Spectroscopy) along with quantum mechanical molecular calculations revealed that organic nitrates and dinitrates were also formed. Secondary organic aerosols (SOA) formation, in the presence of ammonium sulfate seed, was also monitored using SMPS-CPC (Scanning Mobility Particle Sizer-Condensation Particle Counter). The size distribution and the mass concentration of the particles were determined for 2-MF concentration between 80 and 531 ppbv leading to SOA yields 1.03–2.23 %. Finally, SOA formed were chemically characterized using ESI-LC-QToF-MS/MS (Electrospray Ionization Liquid Chromatography – Quadrupole - Time of Flight - Tandem Mass Spectrometer) revealing that oligomers, e.g. highly oxygenated molecules (HOMs) were also formed. Based on our experimental observations, a reaction mechanism is proposed. NO3 radical is predominately added to the C2/C5 double bond of 2-MF, while the H atom abstraction channel, is estimated to be of minor importance. Results from this work provide detailed information about the NO3 radical initiated oxidation of 2-MF that can be used in chemical transport models to simulate the ageing processes occurring in biomass burning plumes.

Decreasing Production and Potential Urban Explosion of Nighttime Nitrate Radicals amid Emission Reduction Efforts.

Nighttime oxidation by nitrate (NO3) radicals has important ramifications on nocturnal aerosol formation and hence the climate and human health. Nitrate radicals are produced by the reaction of NO2 and O3. Despite large decreases in anthropogenic emissions of nitrogen oxides (NOx = NO + NO2), a previous study found significant increases in NO3 production (PNO3) from 2014 to 2019 in China, in contrast to decreasing trends in the U.S. and Europe. Using the summer observations from 2014 to 2022, we analyze the interannual variability of nocturnal PNO3 using a systematic framework, in which PNO3 is diagnosed as a function of odd oxygen (Ox = O3 + NO2) and the NO2/O3 ratio. We did not find an increase of PNO3 from 2014 to 2022 in China due to a continuous decrease in the NO2/O3 ratio, although PNO3 is modulated by the variation in Ox. Using in situ observations obtained in Beijing in 2007, we demonstrate the potential for an upsurge resembling an "explosion" in urban nighttime NO3 radicals amid emission reduction efforts.

Insights into secondary organic aerosol formation from the day- and nighttime oxidation of polycyclic aromatic hydrocarbons and furans in an oxidation flow reactor

Abstract. Secondary organic aerosols (SOAs) formed by oxidation of typical precursors largely emitted by biomass burning, such as polycyclic aromatic hydrocarbons (PAHs) and furans, are still poorly characterized. We evaluated and compared the formation yields, effective density (ρeff), absorption Ångström exponent (α), and mass absorption coefficient (MAC) of laboratory-generated SOAs from three furan compounds and four PAHs. SOAs were generated in an oxidation flow reactor under day- (OH radicals) or nighttime (NO3 radicals) conditions. The ρeff, formation yields, α, and MAC of the generated SOAs varied depending on the precursor and oxidant considered. The ρeff of SOAs formed with OH and NO3 tended to increase with particle size before reaching a “plateau”, highlighting potential differences in SOA chemical composition and/or morphology, according to the particle size. Three times lower SOA formation yields were obtained with NO3 compared with OH. The yields of PAH SOAs (18 %–76 %) were five to six times higher than those obtained for furans (3 %–12 %). While furan SOAs showed low or negligible light absorption properties, PAH SOAs had a significant impact in the UV–visible region, implying a significant contribution to atmospheric brown carbon. No increase in the MAC values was observed from OH to NO3 oxidation processes, probably due to a low formation of nitrogen-containing chromophores with NO3 only (without NOx). The results obtained demonstrated that PAHs are significant SOA precursors emitted by biomass burning, through both, day- and nighttime processes, and have a substantial impact on the aerosol light absorption properties.

Effect of Electron-donating Group on NO Photolysis of {RuNO}6 Ruthenium Nitrosyl Complexes with N2 O2 Lgands Bearing π-Extended Rings.

In this study, we introduced the electron-donating group (-OH) to the aromatic rings of Ru(salophen)(NO)Cl (0) (salophenH2 =N,N'-(1,2-phenylene)bis(salicylideneimine)) to investigate the influence of the substitution on NO photolysis and NO-releasing dynamics. Three derivative complexes, Ru((o-OH)2 -salophen)(NO)Cl (1), Ru((m-OH)2 -salophen)(NO)Cl (2), and Ru((p-OH)2 -salophen)(NO)Cl (3) were developed and their NO photolysis was monitored by using UV/Vis, EPR, NMR, and IR spectroscopies under white room light. Spectroscopic results indicated that the complexes were diamagnetic Ru(II)-NO+ species which were converted to low-spin Ru(III) species (d5 , S=1/2) and released NO radicals by photons. The conversion was also confirmed by determining the single-crystal structure of the photoproduct of 1. The photochemical quantum yields (ΦNO s) of the photolysis were determined to be 0>1, 2, 3 at both the visible and UV excitations. Femtosecond (fs) time-resolved mid-IR spectroscopy was employed for studying NO-releasing dynamics. The geminate rebinding (GR) rates of the photoreleased NO to the photolyzed complexes were estimated to be 0≃1, 2, 3. DFT and TDDFT computations found that the introduction of the hydroxyl groups elevated the ligand π-bonding orbitals (π (salophen)), resulting in decrease of the HOMO-LUMO gaps in 1-3. The theoretical calculations suggested that the Ru-NNO bond dissociations of the complexes were mostly initiated by the ligand-to-ligand charge transfer (LLCT) of π(salophen)→π*(Ru-NO) with both the visible and UV excitations and the decreasing ΦNO s could be explained by the changes of the electronic structures in which the photoactivable bands of 1-3 have relatively less contribution of transitions related with Ru-NO bond than those of 0.

Study of hydroxyl and nitrite radicals concentration in plasma-activated water by photoluminescence spectroscopy

The atmospheric pressure plasma in water has numerous applications, including utilizing reactive species in the dye degradation process for polluted water remediation. In the current study, an air plasma jet generated atmospheric pressure plasma, transporting reactive oxygen and nitrogen species (RONS) onto the solution surface, such as OH and NO2 radicals, which immediately developed in an aqueous solution. The identification and concentration of radicals are determined using photoluminescence spectroscopy (PL) and irradiation over the surface of an aqueous solution. Based on the reaction between hydroxyl ions and terephthalic acid, fluorimetric methods for hydroxyl ions determination are developed. In addition, 2,3-diamino naphthalene was selected for the nitrite reaction. The jet nozzle-to-solution-surface distance, treatment time, and carrier air flow rate substantially impacted determining the radical’s concentration in aqueous solution.

New Mechanistic Insights into the Primary Thermolysis Reactions of 1,3,4,6-Tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX) from Predictive Local Coupled Cluster Calculations.

Theoretical studies of the decomposition mechanism of energetic materials quite often scrutinize only the primary thermolysis reactions. However, the secondary reactions are crucial, inter alia, for proper building of the combustion models and understanding the autocatalytic processes. In the present study, we applied predictive DLPNO-CCSD(T) calculations to elucidate the kinetics and decomposition mechanism of a novel promising energetic material, 1,3,4,6-tetranitrooctahydroimidazo [4,5-d] imidazole (BCHMX). We identified eight previously unknown BCHMX conformers, both cis and trans in accordance to the spatial position of the H atoms bonded to a carbon bridge. Among them, the relative enthalpies of cis isomers lie in the narrow range ∼10 kJ mol-1 rendering them thermally accessible in the course of decomposition. The radical N-NO2 bond cleavage via one of the novel conformers is the dominant primary decomposition channel of BCHMX with the kinetic parameters Ea = 168.4 kJ mol-1 and log(A, s-1) = 18.5. We also resolved several contradictory assumptions on the mechanism and key intermediates of BCHMX thermolysis. To get a deeper understanding of the decomposition mechanism, we examined a series of unimolecular and bimolecular secondary channels of BCHMX. Among the former reactions, the C-C bond unzipping followed by another radical elimination of a nitro group is the most energetically favorable pathway with an activation barrier ∼113 kJ mol-1. However, contrary to the literature assumptions, the bimolecular H atom abstraction from a pristine BCHMX molecule by a primary nitramine radical product, not the nitro one, followed by another NO2 radical elimination, is the most important bimolecular secondary thermolysis reaction of BCHMX at lower temperatures. The isokinetic temperature of the bimolecular and unimolecular secondary reactions is ∼620 K. Unimolecular reactions might be important in dilute solutions, where bimolecular reactions are suppressed. The secondary reactions considered in the present work might be pertinent in the case of related energetic nitramines (e.g., RDX, HMX, and CL-20).

Dominant Contribution of NO3 Radical to NO3- Formation during Heavy Haze Episodes: Insights from High-Time Resolution of Dual Isotopes Δ17O and δ18O.

δ18O is widely used to track nitrate (NO3-) formation but overlooks NO3 radical reactions with hydrocarbons (HCs), particularly in heavily emitting hazes. This study introduces high-time resolution Δ17O-NO3- as a powerful tool to quantify NO3- formation during five hazes in three cities. Results show significant differences between Δ17O-NO3- and δ18O-NO3- in identifying NO3- formation. δ18O-NO3- results suggested N2O5 hydrolysis (62.0-88.4%) as the major pathway of NO3- formation, while Δ17O-NO3- shows the NO3- formation contributions of NO2 + OH (17.7-66.3%), NO3 + HC (10.8-49.6%), and N2O5 hydrolysis (22.9-33.3%), revealing significant NO3 + HC contribution (41.7-56%) under severe pollution. Furthermore, NO3- formation varies with temperatures, NOx oxidation rate (NOR), and pollution levels. Higher NO2 + OH contribution and lower NO3 + HC contribution were observed at higher temperatures, except for low NOR haze where higher NO2 + OH contributions were observed at low temperatures (T ← 10 °C). This emphasizes the significance of NO2 + OH in emission-dominated haze. Contributions of NO2 + OH and NO3 + HC relate to NOR as positive (fP1 = 3.0*NOR2 - 2.4*NOR + 0.8) and negative (fP2 = -2.3*NOR2 + 1.8*NOR) quadratic functions, respectively, with min/max values at NOR = 0.4. At mild pollution, NO2 + OH (58.1 ± 22.2%) dominated NO3- formation, shifting to NO3 + HC (35.5 ± 16.3%) during severe pollution. Additionally, high-time resolution Δ17O-NO3- reveals that morning-evening rush hours and high temperatures at noon promote the contributions of NO3 + HC and NO2 + OH, respectively. Our results suggested that the differences in the NO3- pathway are attributed to temperatures, NOR, and pollution levels. Furthermore, high-time resolution Δ17O-NO3- is vital for quantifying NO3 + HC contribution during severe hazes.

Biocompatibility of ionic liquid tagged terpyridine complexes with potent biological activity

The current work deals with the study of novel and bioactive ionic liquid tagged terpyridine ligand and their complexes were synthesized using first row transition metal ions. The synthesized IL tagged complexes were characterized by UV, FT-IR, 1H NMR, 13C NMR, HRMS spectroscopic studies and also the structure of the complexes was confirmed by its spectral data. Moreover, the antibacterial, antifungal, antioxidant and anticancer studies were carried out to exhibit the bioactivity of the complexes. The antimicrobial studies of newly synthesized complexes were tested against five bacterial and two fungal strains by disc diffusion method. The iron complexes of terpyridine shows outstanding activity than the reference with zone of inhibition of 22-32 mm against the evaluated microorganisms. Furthermore, the antioxidant activity of the terpyridine complexes was assessed by phosphomolybdenum and NO radical scavenging assay. The reducing power of the synthesized complexes has shown potent antioxidant activity than the standard. Especially, Cu-tpy-IL and Zn-ttpy-IL have shown good radical scavenging activity exhibits an IC50 value of 42.45 and 40.85 µg/mL respectively. In addition, the anticancer activity of the complexes was analyzed by SRB assay. The report suggested that the complexes of Cu-ttpy-IL and Zn-ttpy-IL exhibiting prominent role in anticancer activity against HeLa and HT-29 cell lines possessing a GI50 value of <10 µg/mL. The obtained results revealed that the bioactive synthesized complexes could be used as a derivative in the field of drug inventions.

Reaction mechanism and kinetic modeling of gas-phase thermal decomposition of prototype nitramine compound HMX

The combustion, detonation, and explosion chemistry of energetic materials is regulated by the formation and decay of critical intermediates that are generated during the process. In this study, the pyrolysis mechanism of a commonly used cyclic nitramine explosive called octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, also known as HMX or octogen, has been investigated by performing ab initio based RRKM/master equation analysis coupled with kinetic modeling simulations. The potential energy profiles of reaction network were constructed at the DLPNO-CCSD(T)/cc-pV[T,Q]Z level based on B3LYPD3/6-311+G(d,p) optimized geometries. The master equation calculations and kinetic modeling simulations indicated that the N-NO2 bond fission, leading to the formation of HMXR (the radical formed after NO2 loss) and nitro radicals, is the most important channel during the initial decomposition of HMX. The C-N and C-H β-scissions play an important role in the subsequent decomposition of the HMXR radical, with the C-H β-scission to form INT249 being the more favored consumption channel. Furthermore, this study also provided a preliminary exploration into the contribution of bimolecular reactions between HMX and H/OH/NO/NO2 radicals. The kinetic simulation results demonstrated that decomposition through these bimolecular reactions is of negligible importance under the investigated conditions.

Detecting nitrogen oxide emissions in Qatar and quantifying emission factors of gas-fired power plants – a 4-year study

Abstract. Nitrogen oxides (NOx=NO+NO2), produced in urban areas and industrial facilities (particularly in fossil-fuel-fired power plants), are major sources of air pollutants, with implications for human health, leading local and national authorities to estimate their emissions using inventories. In Qatar, these inventories are not regularly updated, while the country is experiencing fast economic growth. Here, we use spaceborne retrievals of nitrogen dioxide (NO2) columns at high spatial resolution from the TROPOspheric Monitoring Instrument (TROPOMI) to estimate NOx emissions in Qatar from 2019 to 2022 with a flux-divergence scheme, according to which emissions are calculated as the sum of a transport term and a sink term representing the three-body reaction comprising NO2 and hydroxyl radical (OH). Our results highlight emissions from gas power plants in the northeast of the country and from the urban area of the capital, Doha. The emissions from cement plants in the west and different industrial facilities in the southeast are underestimated due to frequent low-quality measurements of NO2 columns in these areas. Our top-down model estimates a weekly cycle, with lower emissions on Fridays compared to the rest of the week, which is consistent with social norms in the country, and an annual cycle, with mean emissions of 9.56 kt per month for the 4-year period. These monthly emissions differ from the Copernicus Atmospheric Monitoring Service global anthropogenic emissions (CAMS-GLOB-ANT_v5.3) and the Emissions Database for Global Atmospheric Research (EDGARv6.1) global inventories, for which the annual cycle is less marked and the average emissions are respectively 1.67 and 1.68 times higher. Our emission estimates are correlated with local electricity generation and allow us to infer a mean NOx emission factor of 0.557 tNOx GWh−1 for the three gas power plants in the Ras Laffan area.

Src Tyrosine Kinase Inhibitory and Antioxidant Activity of Black Chokeberry and Bilberry Fruit Extracts Rich in Chlorogenic Acid.

Edible berries such as the fruits of black chokeberry (Aronia melanocarpa (Michx.) Elliott) and bilberry (Vaccinium myrtillus L.) are considered to be rich in phenolic compounds, which are nowadays attracting great interest due to their promising health benefits. The main objective of our study was to investigate, for the first time, their inhibitory properties on Src tyrosine kinase activity, as this enzyme plays an important role in multiple cellular processes and is activated in both cancer and inflammatory cells. In hydroethanolic fruit extracts, 5.0-5.9% of total polyphenols were determined spectrophotometrically, including high amounts of hydroxycinnamic acid derivatives. HPLC analysis revealed that the black chokeberry and bilberry extracts contained 2.05 mg/g and 2.54 mg/g of chlorogenic acid, respectively. Using a time-resolved fluorescence resonance energy transfer (TR-FRET) assay, the extracts studied were found to have comparable inhibitory effects on Src tyrosine kinase, with IC50 values of 366 µg/mL and 369 µg/mL, respectively. The results also indicated that chlorogenic acid contributes significantly to the observed effect. In addition, both fruit extracts exhibited antioxidant activity by scavenging DPPH and NO radicals with SC50 values of 153-352 µg/mL. Our study suggested that black chokeberry and bilberry fruits may be beneficial in cancer and other inflammation-related diseases.

The Potential of Mangifera indica L. Peel Extract to Be Revalued in Cosmetic Applications.

The constant growth of the cosmetic industry, together with the scientific evidence of the beneficial properties of phytochemicals, has generated great interest in the incorporation of bioactive extracts in cosmetic formulations. This study aims to evaluate the bioactive potential of a mango peel extract for its incorporation into cosmetic formulations. For this purpose, several assays were conducted: phytochemical characterization; total phenolic content (TPC) and antioxidant potential; free-radical scavenging capacity; and skin aging-related enzyme inhibition. In addition, the extract was incorporated into a gel formulation, and a preliminary stability study was conducted where the accelerated (temperature ramp, centrifugation, and heating/cooling cycles) and long-term (storage in light and dark for three months) stability of the mango peel formulations were evaluated. The characterization results showed the annotation of 71 compounds, gallotannins being the most representative group. In addition, the mango peel extract was shown to be effective against the •NO radical with an IC50 of 7.5 mg/L and against the hyaluronidase and xanthine oxidase enzymes with IC50 of 27 mg/L and 2 mg/L, respectively. The formulations incorporating the extract were stable during the stability study. The results demonstrate that mango peel extract can be a by-product to be revalorized as a promising cosmetic ingredient.

Ventilation in a Residential Building Brings Outdoor NOx Indoors with Limited Implications for VOC Oxidation from NO3 Radicals.

Energy-efficient residential building standards require the use of mechanical ventilation systems that replace indoor air with outdoor air. Transient outdoor pollution events can be transported indoors via the mechanical ventilation system and other outdoor air entry pathways and impact indoor air chemistry. In the spring of 2022, we observed elevated levels of NOx (NO + NO2) that originated outdoors, entering the National Institute of Standards and Technology (NIST) Net-Zero Energy Residential Test Facility through the mechanical ventilation system. Using measurements of NOx, ozone (O3), and volatile organic compounds (VOCs), we modeled the effect of the outdoor-to-indoor ventilation of NOx pollution on the production of nitrate radical (NO3), a potentially important indoor oxidant. We evaluated how VOC oxidation chemistry was affected by NO3 during NOx pollution events compared to background conditions. We found that nitric oxide (NO) pollution introduced indoors titrated O3 and inhibited the modeled production of NO3. NO ventilated indoors also likely ceased most gas-phase VOC oxidation chemistry during plume events. Only through the artificial introduction of O3 to the ventilation duct during a NOx pollution event (i.e., when O3 and NO2 concentrations were high relative to typical conditions) were we able to measure NO3-initiated VOC oxidation products, indicating that NO3 was impacting VOC oxidation chemistry.

Combustion characteristics of premixed ammonia-hydrogen/air flames in a swirl model combustor

Ammonia (NH3)-hydrogen (H2) blends based on the thermal cracking of NH3 are considered as a prominent carbon-free fuel. This study aims to provide the combustion characteristics of premixed NH3-H2(-N2)/air swirl flames under various conditions of fuel-equivalence ratio (ϕ) and H2 content in the fuel blend (xh,f). Results show four representative types of premixed NH3-H2(-N2)/air flames depending on ϕ. Combustion stability limits are extended with increasing xh,f and through the transition from laminar to turbulent combustion condition. With increasing xh,f, NOx emissions are enhanced and their peak values are observed to fuel-leaner condition. The deNOx effect of NH3 is enhanced with increasing xh,f, and different main pathways for the oxidation of NH3 to NO are found depending on ϕ. Flame visualization including the distributions of OH(∗) and NO radicals indicates that OH promotes NO production. No remarkable discrepancies of the combustion characteristics between the premixed NH3-H2/air and NH3-H2-N2/air flames are found.