Extra OH Research Articles

A Universal Coulombic Efficiency Compensation Strategy for Zinc-Based Flow Batteries.

Alkaline zinc-iron flow batteries (AZIFBs) are well suited for energy storage because of their good safety, high cell voltage, and low cost. However, the occurrence of irreversible anodic parasitic reactions results in a diminished coulombic efficiency (CE), unbalanced charge state of catholyte/anolyte and subsequently, a poor cycling performance. Here, a universal CE compensation strategy centered around the oxygen evolution reaction (OER) on the cathodic side, is reported. This strategy aims to equalize the charge state of the [Fe(CN)6]3-/4--based catholyte and counteract pH fluctuations. The OER process can be implemented either directly on the electrode through electrochemical reaction or in an external catalytic reactor column via a redox-mediated process. This innovative approach effectively mitigates the gradual accumulation of [Fe(CN)6]3- in discharged catholyte and [Zn(OH)4]2- in charged anolyte by consuming the extra OH- during a continuous cycling process. As a result, AZIFBs demonstrate exceptional cycling performance with an extremely low capacity fading rate of 0.0128%/day (or 0.0005%/cycle) over 600 cycles at 80% state of charge (SOC). The proposed CE compensation strategy not only provides an effective way to address the CE loss issue for AZIFBs, but also can be applied to diverse battery technologies encountering CE loss caused by water/oxygen-induced parasitic reactions.

Fabrication of Dual-Functional Bacterial-Cellulose-Based Composite Anion Exchange Membranes with High Dimensional Stability and Ionic Conductivity.

Anion exchange membranes (AEMs) are increasingly becoming a popular research area due to their ability to function with nonprecious metals in electrochemical devices. Nevertheless, there is a challenge to simultaneously optimize the dimensional stability and ionic conductivity of AEMs due to the "trade-off" effect. Herein, we adopted a novel strategy of combining filling and cross-linking using functionalized bacterial cellulose (PBC) as a dual-functional porous support and brominated poly(phenylene oxide) (Br-PPO) as the cross-linking agent and filler. The PBC nanofiber framework together with cross-linking can provide a reliable mechanical support for the subsequent filled polymer, thus improving the mechanical properties and effectively limiting the size change of the final quaternized-PPO (QPPO)-filled PBC composite membrane. The composite membrane showed a very low swelling ratio of only 10.35%, even at a high water uptake (81.83% at 20 °C). Moreover, the existence of multiple -NR3+ groups in the cross-link bonds between BC and Br-PPO can provide extra OH- ion transport sites, contributing to the increase in ionic conductivity. The final membrane demonstrated a hydroxide ion conductivity of 62.58 mS cm-1, which was remarkably higher than that of the pure QPPO membrane by up to 235.93% (80 °C). The successful preparation of the PBC3/QPPO membrane provides an effective avenue to tackle the trade-off effect through a dual-functional strategy.

Facile synthesis of multi-layer Co(OH)2/CeO2-g-C3N4 ternary synergistic heterostructure for efficient photocatalytic oxidation of NO under visible light

In this work, we report a one-step synthesis of ternary Z-scheme Co(OH)2/CeO2-g-C3N4 (CoCe-CN) heterostructure via hydrothermal method. Owing to the modification of Co(OH)2 and CeO2, the existence of Co(OH)2 as an electron acceptor-donor center between CeO2 and g-C3N4 accelerates the electron transfer and provides extra OH- reaction pathway for photocatalytic oxidation of NO. As a result, 50CoCe-CN (Co and Ce accounting for 25% mass ratio separately) achieved a 53.5% conversion efficiency of NO at 600 ppb concentration, which is 1.82 times that of g-C3N4 under visible light. The results of the DFT analysis and element distribution of cobalt and ceria provide convincing evidence supporting the existence of a novel multi-layer structure in the CoCe-CN photocatalyst. This structure involves the loading of CeO2 and Co(OH)2 on the g-C3N4 surface, and Co(OH)2 as a co-catalyst introduced between CeO2 and g-C3N4 realizes the synergy between CeO2 and Co(OH)2 which further improve the photocatalytic properties. The higher photocatalytic efficiencies observed in the CoCe-CN photocatalysts compared to those containing only cobalt (Co-CN) or ceria (Ce-CN) provide further evidence of the synergistic effect of these two elements. This work demonstrates a more efficient and effective ternary photocatalytic system, with greater practical potential for photocatalytic oxidation of NO.

Ultraviolet Light-Driven gaining of hydroxyl and nitrogen oxide radicals in Plasma–Treated water

Here we numerically demonstrate that photolytic processes induced by external ultraviolet (UV) sources considerably affect the chemical properties of plasma–water systems. When describing the chemical transport between surface dielectric barrier discharge (SDBD) and deionized water, the plasma is simulated using a global model, while the gas (air) and liquid (water) regions are considered in a one-dimensional space. Our simulation involving exposure of plasma-treated water (PTW) to UV shows that long-lived species in PTW are readily photolyzed and form hydroxyl radical (OH) and nitric oxide (NO) over the entire liquid region. The total OH concentration was enhanced by 11.6 times at 100 s under exposure to a conventional UV lamp, while the total NO concentration was remarkably enhanced up to 45.8 times at 300 s. The time at which the OH concentration notably increases was advanced by more than 100 s by photolytic processes. The results directly reveal that the exposure of PTW to UV is an attractive approach to selectively releasing extra OH and NO, thereby increasing the PTW reactivity and applicability. Owing to their high reactivity and oxidizing power, the short lifetime of radicals including OH and NO in PTW, which is crucial in diverse applications, has been troublesome. In this regard, our findings will provide new guidance in utilizing PTW for various applications.

Unraveling the adsorption behaviors of uranium and thorium on the hydroxylated titanium carbide MXene

Hydroxylated titanium carbide Ti3C2(OH)2, a representative of MXenes, is employed to investigate adsorption behaviors for uranium and thorium using density functional theory based simulation methods. The structural analysis of the complexes compares very well to existing computational and experimental literatures. A closer look at the adsorption configurations and energies indicates that the main adsorption sites are deprotonated Os atoms of the OH groups terminated on the Ti3C2(OH)2 MXene surface. The most stable models for U(VI) and Th(IV) adsorbed on the Ti3C2(OH)2 MXene in the gas phase are bidentate and tridentate configurations, respectively. The adsorption ability of Th(IV) on the Ti3C2(OH)2 MXene is stronger than that of U(VI). More importantly, the aqueous solution has a remarkable effect on the coordinated environment of uranyl and Th4+ ions in the binding configurations. Uranyl and Th4+ ions adsorbed on the Ti3C2(OH)2 MXene in the aqueous environment form pentavalent coordinated structures. Extra OH– ligands from water molecules are found to interact with U and Th atoms compared with the adsorption configurations in the gas phase. Moreover, U-Oax double bonds in the uranyl break to form U-OH bonds in the adsorption model. For all the stable adsorption configurations, the coordinating interaction is the dominant factor, and Th-Os bonds present more covalent nature than U-Os bonds due to the larger charge transfers between Th and Os atoms. This work gives supplement to the experimental observations and will provide deeper insights into the physical chemistry behind the removal of uranium and thorium by using MXenes.

Crystal Structure of Moganite and Its Anisotropic Atomic Displacement Parameters Determined by Synchrotron X-ray Diffraction and X-ray/Neutron Pair Distribution Function Analyses

The crystal structure of moganite from the Mogán formation on Gran Canaria has been re-investigated using high-resolution synchrotron X-ray diffraction (XRD) and X-ray/neutron pair distribution function (PDF) analyses. Our study for the first time reports the anisotropic atomic displacement parameters (ADPs) of a natural moganite. Rietveld analysis of synchrotron XRD data determined the crystal structure of moganite with the space group I2/a. The refined unit-cell parameters are a = 8.7363(8), b = 4.8688(5), c = 10.7203(9) Å, and β = 90.212(4)°. The ADPs of Si and O in moganite were obtained from X-ray and neutron PDF analyses. The shapes and orientations of the anisotropic ellipsoids determined from X-ray and neutron measurements are similar. The anisotropic ellipsoids for O extend along planes perpendicular to the Si-Si axis of corner-sharing SiO4 tetrahedra, suggesting precession-like movement. Neutron PDF result confirms the occurrence of OH over some of the tetrahedral sites. We postulate that moganite nanomineral is stable with respect to quartz in hypersaline water. The ADPs of moganite show a similar trend as those of quartz determined by single-crystal XRD. In short, the combined methods can provide high-quality structural parameters of moganite nanomineral, including its ADPs and extra OH position at the surface. This approach can be used as an alternative means for solving the structures of crystals that are not large enough for single-crystal XRD measurements, such as fine-grained and nanocrystalline minerals formed in various geological environments.

Engineering of a highly stable metal-organic Co-film for efficient electrocatalytic water oxidation in acidic media

Water oxidation is traditionally performed over IrO2 and RuO2 owing to their high stability at low pH compared to molecular O2 evolution catalysts. The low stability of molecular complexes in acids limits their industrial exploitation as anodes in water-splitting devices, where high current densities and proton conductivity are required. Herein, an existing Co(1,10-phenanthroline)2 complex film is engineered to improve its pH-stability via extra OH substituents on the ligand, i.e. 1,10-phenanthroline-4,7-diol. This novel Co(1,10-phenanthroline-4,7-diol)2 complex film is active for water oxidation at low overpotentials and stable at low pH. Since the calculated water oxidation overpotentials of both complexes are similar, the difference in water oxidation activity is attributed to a smaller charge transfer resistance, which originates from a different anchoring style to the electrode via the OH groups of the ligand. This result is supported by electrochemical impedance measurements. The high pH-stability of the Co(1,10-phenanthroline-4,7-diol)2 film is computationally rationalized by a high crystal formation energy observed in DFT calculations. In summary, an acid-stable and active cobalt-based metal-organic film is reported that competes well with most reported earth-abundant catalysts for water oxidation under similar conditions.

Crystalline structure variation within phlogopite, muscovite and talc under 0–1000 kGy γ ray irradiation: A clear dependence on intrinsic characteristic

A clear cognition on how structure difference affects crystalline structure variation within phyllosilicate especially for “2:1” layered phyllosilicate under irradiation is essential to explore the procedure for damage formation within matrix of clay used in disposal high radioactive waste (HLRW) practically and also beneficial for evaluating the effect of nuclear accident to environment, which is of great significance. In this work, phlogopite, muscovite and talc were irradiated by Co-60 γ rays in air at a dose rate of 54 Gy/min with doses at 0–1000 kGy. Then, variation in crystalline structure and intrinsic mechanism were explored. Main results show phlogopite occurred expansion while muscovite and talc occurred shrink in z-direction lattice. Simultaneously, H2O amount declined and valence for metal was elevated. For 1000 kGy-irradiated sample, interlayer space d varied 1% and binding energy for metal was elevated near 1.5–2 eV. It seems phlogopite, muscovite and talc show poor radiation-resistance. Main mechanisms involve intrinsic characteristic, framework break and H2O radiolysis. Upon irradiation, framework break and H2O radiolysis occurred synchronously. Framework break mainly resulted in shrink, H2O radiolysis mainly led extra OH introduction leading expansion. In reality, all these three materials showed extra OH introduction while only phlogopite occurred expansion. It seems the variation trend in lattice mainly relies on material's intrinsic characteristic, H2O radiolysis is secondary. To talc or muscovite, for compact stacking or idle space existence, they are difficult to expand, lattice shrink observed even under extra OH introduction. To phlogopite, for moderate structure, its lattice is easy to expand. For 1000 kGy-irradiated sample, the interlayer space d was enlarged by 1%. For H2O radiolysis, its amount declined and HO• radical was formed, elevating valence for metal as Mg/Al. It seems phyllosilicate shows poor radiation-resistance, and the apparent variation trend in lattice induced by γ ray irradiation seems mainly rely on material's intrinsic characteristic, H2O radiolysis is secondary.

Intensive study on structure transformation of muscovite single crystal under high-dose γ-ray irradiation and mechanism speculation.

Intensive study on structure transformation of muscovite single crystal under high-dose γ-ray irradiation is essential for its use in irradiation detection and also beneficial for mechanism cognition on defect formation within a matrix of clay used in the disposal of high-level radioactive waste (HLRW). In this work, muscovite single crystal was irradiated with Co-60 γ ray in air at a dose rate of 54 Gy min−1 with doses of 0–1000 kGy. Then, structure transformation and mechanism were explored by Raman spectrum, Fourier-transform infrared spectrum, X-ray diffraction, thermogravimetric analysis, CA, scanning electron microscope and atomic force microscopy. The main results show that variations in the chemical/crystalline structure are dose-dependent. Low-dose irradiation sufficiently destroyed the structure, removing Si–OH, thus declining hydrophilicity. With dose increase up to 100 kGy, CA increased from 20° to 40°. Except for hydrophilicity variation, shrink occurred in the (004) lattice plane which later recovered; the variation range at 500 kGy irradiation was 0.5% close to 0.02 Å. The main mechanisms involved were framework break and H2O radiolysis. Framework break results in Si–OH removal and H2O radiolysis results in extra OH introduction. The extra introduced OH probably results in Si–OH bond regeneration, lattice plane shrink and recovered surface hydrophilicity. The importance of framework break and H2O radiolysis on structure transformation is dose-dependence. At low doses, framework break seems more important while at high doses H2O radiolysis is important. Generally, variations in the chemical structure and surface property are nonlinear and less at high doses. This indicates using the chemical structure or surface property variation to describe irradiation is correct at low doses but not at high doses. This finding is meaningful for realizing whether muscovite is suitable for detecting high-dose irradiation or not, and mechanism exploration is efficient for identifying the procedure for defect formation within the matrix of clay used in disposal HLRW in practice.

Novel sodium alkyl-1,3-disulfates, anionic biosurfactants produced from microbial polyesters

A sodium alkyl disulfate mixture (SADM) synthesised from microbially produced 3-hydroxy fatty acids methyl esters (HFAMEs), showed 13-fold surface tension decrease when compared with the reference surfactant sodium dodecyl sulfate (SDS). Polyhydroxyalkanoates, accumulated by bacteria intracellularly when supplied with a mixture of fatty acids derived from hydrolysed rapeseed oil, were isolated, depolymerised and methylated to produce HFAMEs in very high yield (90%). A sequential chemical reduction and sulfation of the HFAMEs produced the sodium alkyl disulfates in high yields (>65%). SADM performs also 1.3-times better than dodecyl (1,3) disulfate, in surface tension tests. SADM shows also the formation of a specific critical micelle concentration (CMC) at a concentration 21-fold lower than SDS. The wettability of the SADM mixture is similar to SDS but the foaming volume of SADM is 1.5-fold higher. The foam is also more stable with its volume decreasing 3 times slower over time compared to SDS at their respective CMC values. Established sulfation technologies in chemical manufacturing could use the 3-hydroxy fatty acids methyl esters moiety (3-HFAME) given its origin from rapeseed oil and the extra OH residue on 3-position in the molecule, which affords the opportunity to produce disulfate surfactants with a proven superior performance to monosulphated surfactants. Thus, not only addressing environmental issues by avoiding threats of deforestation and monocultivation associated with palm oil use but also achieve a higher performance with lower use of surfactants.

Dispersion of triethanolamine-functionalized graphene oxide (TEA-GO) in pore solution and its influence on hydration, mechanical behavior of cement composite

Abstract Re-aggregation of graphene oxide (GO) in cementitious solutions compromises the mechanical enhancement of cement composite. We chemically functionalized GO via triethanolamine (TEA), the removal of C O C groups on basal planes and the attachment of extra OH groups on edges promoted its dispersibility during hydration and in cement paste. When incorporated into cement, TEA-GO provides more nucleation sites due to the better dispersion, further promoting the hydration degree. TEA-GO enhanced the compressive strength and flexural strength by 9.4–31% and 8.1–36.7% respectively, which was significantly higher than that of GO(4.1–17.2%; 7.8–20%).

NEW TRANS-1,2- CYCLOHEXYLDIAMINO-NN,N’N’ (CH2CO2)(CH2CO2H)3 ANION CONTAINING ADDUCTS AND DERIVATIVES: SYNTHESIS AND INFRARED STUDY

<p>Five Cyclohexyldiamino-NN, N’N’(CH<sub>2</sub>CO<sub>2</sub>)(CH<sub>2</sub>CO<sub>2</sub>H)<sub>3</sub> anion containing adducts and derivatives with tin, antimony and mercury halides have been synthesized and characterized by infrared spectroscopy. The suggested structures are discrete, the anion behaving as a monodentate or a monochelating ligand: the environments around the metallic centres are trigonal bipyramidal or octahedral.The carboxylic groups and the cation, when involved in extra OH---O, OH----Cl or NH---Cl or O hydrogen bonds may lead to supramolecular architectures.</p>

NEW TRANS-1,2- CYCLOHEXYLDIAMINO-NN,N’N’ (CH2CO2)(CH2CO2H)3 ANION CONTAINING ADDUCTS AND DERIVATIVES: SYNTHESIS AND INFRARED STUDY

Five Cyclohexyldiamino-NN, N’N’(CH2CO2)(CH2CO2H)3 anion containing adducts and derivatives with tin, antimony and mercury halides have been synthesized and characterized by infrared spectroscopy. The suggested structures are discrete, the anion behaving as a monodentate or a monochelating ligand: the environments around the metallic centres are trigonal bipyramidal or octahedral.The carboxylic groups and the cation, when involved in extra OH---O, OH----Cl or NH---Cl or O hydrogen bonds may lead to supramolecular architectures.

Synthesis of porous CuO microspheres assembled from (001) facet-exposed nanocrystals with excellent glucose-sensing performance

Hierarchical porous CuO microspheres are successfully synthesized through a facile hydrothermal method using Na2HPO4-NaOH buffer solution as solvent. The SEM and TEM results reveal that the CuO microspheres are assembled by (001) facet-exposed nanocrystals. The BET result indicates that the CuO microspheres have a surface area of 61.9 m2 g−1 and an average pore size of ∼3.7 nm. Moreover, it is found that the buffer solution not only serves as reactant and medium, but also affects the final shape of the CuO microspheres. The buffer solution can supply a suitable amount of OH− ions, which leads to no extra OH− ions absorb on the original crystals, thus favoring to form into 3D spherical microstructure. In addition, the CuO microspheres are used as the electrodic material for non-enzymatic glucose sensor, which present low detection limit (0.50 μM), fast amperometric response time (3 s), and wide linear range (0.001–4.0 mM). The improved electrocatalytic performance is ascribed to the synergistic effect of exposure of (001) facet, large special surface area, and porous structure.

Synthesis and immunological evaluation of fluorinated alpha-C-galactosylceramide analogs

A synthesis of difluorinated alpha-C-galactosylceramides analogs featuring an extra hydroxy group in 1' - position is reported. These compounds were prepared according to unprecedented and unusual methodologies that were previously reported by the authors on simpler substrates. Unfortunately, all four compounds, which feature different lipidic chain lengths, failed to activate iNKT cells. The question whether it is due to the anomeric oxygen/CF transposition or to the presence of the extra OH group 2 remains unanswered.

Synthesis and immunological evaluation of fluorinated α-C-galactosylceramide analogs

Abstract A synthesis of difluorinated α-C-galactosylceramides analogs featuring an extra hydroxy group in 1′-position is reported. These compounds were prepared according to unprecedented and unusual methodologies that were previously reported by the authors on simpler substrates. Unfortunately, all four compounds, which feature different lipidic chain lengths, failed to activate iNKT cells. The question whether it is due to the anomeric oxygen/CF 2 transposition or to the presence of the extra OH group remains unanswered.

The atmospheric degradation pathways of BrCH2O2: Computational calculation on mechanisms of the reaction with HO2

Mechanisms for the atmospheric degradation reaction of BrCH2O2+HO2 were investigated using quantum chemistry methods. The result indicates that the dominant product is BrCH2OOH+O2(3Σ). While CH2O+HBr+O3, BrCHO+OH+HO2 and CH2O+Br+HO3 will be competitive to a certain extent in the atmosphere. Meanwhile, the nascent product – BrCH2OOH reacts easily with OH radicals leading to BrCH2O2 again under the atmospheric conditions. Moreover, OH radicals could act as a catalyst in the net reaction of BrCH2OOH→BrCHO+H2O. Thus the proposed product BrCHO+H2O+O2 in the experiment might be generated from the subsequent reaction of BrCH2OOH with extra OH radicals. Comparisons indicate that halogen substitution effect makes minor contributions to the XCH2O2 (X=H, F, Cl and Br)+HO2 reactions in the atmosphere.

The Entry of HCl through Soluble Surfactants on Sulfuric Acid: Effects of Chain Branching

Gas-liquid scattering experiments are used to determine how a soluble, branched surfactant (2-ethylbutanol) controls the entry of gaseous HCl molecules into 60 and 68 wt % D2SO4 at 213 K. Short-chain alcohols spontaneously segregate to the surfaces of these sulfuric acid solutions, which are representative of aerosol droplets in the lower stratosphere. We find that 2-ethylbutanol enhances HCl entry at low surface coverages, most likely because it provides extra interfacial OH groups that aid HCl dissociation. This enhancement disappears at higher coverages as the alkyl chains crowd each other and block access to the acid. The branched alcohol impedes HCl entry more effectively than its unbranched isomer 1-hexanol, implying that the larger 2-ethybutanol footprint on the surface blocks more HCl molecules from reaching the alcohol-acid interface. This behavior contrasts sharply with gas transport through long-chain monolayers, where branching introduces gaps that allow more facile passage. The experiments suggest that short-chain surfactants with extended footprints may impede transport more effectively than their unbranched isomers.

Evaluation of the antibacterial potential of polyphenols against periodontal pathogens

Periodontal disease is a common, chronic infectious disease triggered by the bacterial biofilm of dental plaque resulting in inflammatory loss of the tooth supporting tissues (1) . Globally, it affects 5‐70% of the older (above 65 years) population (2) and can impact on their diet and nutrition leading to weight loss, as well as increase the risk for chronic diseases like diabetes mellitus and cardiovascular disease (3) .I n recent years, specific dietary compounds, especially the polyphenolics have attracted scientific attention due to their health promoting potential. As a regular constituent of the human diet, polyphenols offer a promising alternative in the prevention of microbiota-related oral diseases via their relative safety (at physiological level) and antioxidant, antibacterial and, anti inflammatory potentials (4) . For successful manipulation of polyphenols in functional foods and healthcare products, it is necessary to study their antibacterial effects. The aim of the present study was to evaluate the antibacterial activity of a range of polyphenols against selected periodontal pathogens, with emphasis on structure-function relationship. Polyphenolic compounds (n = 46, from 8 subgroups) were screened for their antimicrobial activity against four periodontal pathogens: two aerobic, Streptococcus mitis (Sm) and Actinobacillus actinomycetocommitans (Aa) and two anaerobic, Fusobacterium nucleatum (Fn) and Porphyromonas gingivalis (Pg). The antimicrobial potential of each compound was evaluated in terms of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using plate dilution assay following standard clinical and laboratory (CLSI) guidelines. Chlorhexidine (0.2%), well known for its antimicrobial properties, was used as a reference. All polyphenols tested displayed antimicrobial properties against one or more test strains except kaempferol-3-glucoronoid, epicatechin, malvin (highest concentration tested: 250 mg/ml), theaflavin, procyanidin B2 (highest concentration tested: 125 mg/ml). Curcumin was found to be the most potent with MIC range of 7.81‐62.5 mg/ml against all test strains (highest activity against pg and Fn), followed by pyrogallol (MIC 2.4‐312.5 mg/ml) and pyrocatechol (MIC 4.88‐312.5 mg/ml) which were highly effective against Sm and Aa. Apigenin and diadzein were only effective against anaerobic bacteria (MIC 15.6‐125 mg/ml and 15.6‐500 mg/ml, respectively). MBC for most of the polyphenols was either the same or twice the MIC. More polyphenolic compounds were effective in inhibiting the growth of the Gram - ve Aa (34/46 tested) than the growth of the Gram +ve Sm (23/46 tested); the concentration needed was 3 times lower, with a mean MIC of 341.0 mg/ml (SD 94) vs. a mean MIC of 1061.8 mg/ml (SD 921), p <0.001. Aglycones were more potent inhibitors of growth compared to their corresponding glycosides in all strains: mean MIC 122.1 mg/ml (SD 117) vs. 519.5 mg/ml (SD460), respectively, p <0.001. With the presence of an extra OH group, the MIC against Aa decreased (3-hydroxybenzoic acid vs. 3,4-dihydroxybenzoic acid vs. 3,4,5-trihydroxybenzoic acid; 625 mg/ml vs. 312.5 mg/ml vs. 9.6 mg/ml). The MIC against Aa was also affected by location of the OH group (1,2-dihydroxybenzene vs. 1,3-dihydroxybenzene; MIC 4.88 mg/ml vs. 1250 mg/ml). This study shows that polyphenols are endowed with antibacterial properties against periodontopathic bacteria, indicating that they have the potential to prevent periodontal diseases. These properties are affected by bacterial strain and properties as well as the structure of the polyphenolic molecule.

Study of ozone-enhanced combustion in H2/CO/N2/air premixed flames by laminar burning velocity measurements and kinetic modeling

The enhancement effect of ozone addition for H2/CO/N2/Air premixed flames at ambient condition is investigated both experimentally and computationally. Adiabatic laminar velocities under different amount of O3 addition were directly measured using the Heat Flux Method. The ozone concentration in the oxidizer is monitored online to ensure the precise control and stability of ozone injection. Experimental data shows significant enhancement of the burning velocities due to O3 addition. With 8500 ppm ozone seeded, maximum 18.74% of burning velocity enhancement is observed at equivalence ratio Φ = 0.7. Kinetic modeling works were conducted by integrating ozone sub-mechanism with three kinetic mechanisms: GRI-Mech 3.0, Davis mechanism and USC Mech II. The modeling results were compared with experimental data. GRI-Mech 3.0 + Ozone mechanism demonstrated the ability to reproduce the experimental data. Extra OH radicals promoted by ozone was found in the pre-heat regime which initiates the chain-branching reaction and results in the combustion enhancement.