Antioxidant Activity of Substituted Enterolactone Derivatives in the Gas Phase and Water

ABSTRACT The antioxidant activity of ortho and meta substituted Enterolactone derivatives has been investigated in the gas phase and water.The reaction enthalpies of antioxidant activity of the studied derivatives have been calculated and compared with the corresponding values of Enterolactone.Results show that EWG substituents increase the BDE and IP,while the EDG ones rise in the PA.The Enterolactone derivatives with the lowest BDE,IP and PA values were identified as the compounds with high antioxidant activity.Results show that the substituents in the ortho position have high potential for the synthesis of novel Enterolactone derivatives.Results show that Enterolactone derivatives can processes their protective role via HAT and SPLET mechanism in gas phase and solvent,respectively.The calculated reaction enthalpies of the substituted Enterolactones have linear dependence with Hammett constants and EHOMO that can be utilized in the selection of suitable substituents for the synthesis of novel antioxidants based on Enterolactone.     

A Quantum Chemical Investigation on the Antioxidant Activity of Licoisoflavone Derivatives

In this paper,21 substituents with various electron donating and electron withdrawing characters were placed in the available positions of Licoisoflavone in order to study their effect on the three O–H bond dissociation enthalpies and ionisation potential via DFT/B3LYP method.Results show that the B-ring is more important than the A-ring from the BDE and IP point of view because the radical structure formed after hydrogen atom abstraction from the 4-OH group can be stabilized by the resonance between the three rings.The results show that intramolecular hydrogen bonding effects are able to considerably stabilize the parents and radicals.The NBO analysis results also confirmed the intramolecular hydrogen bond stabilization.The formation of strong intramolecular hydrogen bonds and suitable spin density distributions in several radicals result in low BDE and IP values.The calculated BDE and IP values have been correlated with Hammett constants.The found dependencies are suitably linear,which can be important for the synthesis of novel antioxidants based on Licoisoflavone.     

Theoretical Analysis on Fully Differential Cross-Sections for C^6＋ Single Ionization of Helium

The four-body model has been used to calculate the fully differential cross-sections （FDCS） for the single ionization of helium by 100 MeV/amu Ca^＋ impact in geometries. By comparing with experimental data and other theories, we find the results of four-body model are in very good agreement in the scattering plane, but poor agreement out of the scattering plane. Accordingly, the contributions of different scattering amplitudes to FDCS are analyzed. It is found that the cross sections due to the interference of the scattering amplitudes between projectile-target nucleus interaction and projectile-ejected electron interaction almost tend to experimental results around the recoil region in geometries. In particular in the perpendicular plane, the cross section originating from interference of the scattering amplitudes between projectile-target nucleus and projectile-ejected electron interactions yields an experimental double-peak structure in the angular distribution. However, this feature could not be presented by the interference of the three amplitudes. Thus, the failure of the fourbody model predicting the feature in this geometry may be attributed to an inappropriate weighting of the three amplitudes.     

Quasi-classical Trajectory Study of F-I-H20→HF-I-OH Reaction： Influence of Barrier Height,Reactant Rotational Excitation,and Isotopic Substitution

The reaction dynamics of the F＋H20/D20→HF/DF＋OH/OD are investigated on an accurate potential energy surface （PES） using a quasi-classical trajectory method. For both isotopomers, the hydrogen/deuterium abstraction reaction is dominated by a direct rebound mechanism over a very low ＂reactant-like＂ barrier, which leads to a vibrationally hot HF/DF product with an internally cold OH/OD companion. It is shown that the lowered reaction barrier on this PES, as suggested by high-level ab initio calculations, leads to a much better agreement with the experimental reaction cross section, but has little impact on the product state distributions and mode selectivity. Our results further indicate that rotational excitation of the H20 reactant leads to significant enhancement of the reactivity, suggesting a strong coupling with the reaction coordinate.     

Low Temperature Heat Capacities and Thermodynamic Properties of Zinc L-Threonate Zn（C4H7O5）2（s） by Adiabatic Calorimetry

Low-temperature heat capacities of the solid compound Zn（C4H7O5）2（s） were measured in a temperature range from 78 to 374 K, with an automated adiabatic calorimeter. A solid-to-solid phase transition occurred in the temperature range of 295？322 K. The peak temperature, the enthalpy, and entropy of the phase transition were determined to be （316.269±1.039） K, （11.194±0.335） kJ？mol-1, and （35.391±0.654） J？K-1？mol-1, respectively. The experimental values of the molar heat capacities in the temperature regions of 78？295 K and 322？374 K were fitted to two polynomial equations of heat capacities（Cp,m） with reduced temperatures（X） and [X = f（T）], with the help of the least squares method, respectively. The smoothed molar heat capacities and thermodynamic functions of the compound, relative to that of the standard reference temperature 293.15 K, were calculated on the basis of the fitted polynomials and tabulated with an interval of 5 K. In addition, the possible mechanism of thermal decomposition of the compound was inferred by the result of TG-DTG analysis.     

Synthesis,characterization, thermal stability and antibacterial activity of coumarin based methacrylate copolymers

Monomer of 7-methacryloyloxy-4-methylcoumarin(MAOMC) was synthesized and characterized by FTIR, 1H-NMR and 13C-NMR spectroscopy. Copolymers of MAOMC with butoxyethylmethacrylate(BOEMA) at different feed compositions were prepared by free radical solution polymerization at(70 ± 1) °C in ethylmethylketone(EMK) using benzyl peroxide(BPO) as an initiator. The copolymers were characterized by FTIR and 1H-NMR spectroscopy. Thermogravimetric analysis(TGA) and differential scanning calorimetry(DSC) of the copolymers showed moderate thermal stability and higher Tg values. Gel permeation chromatography(GPC) was used to find out the molecular weights of the different copolymers. Antibacterial activities of the copolymers were also investigated against the selected pathogenic bacteria's. The antibacterial activity of the copolymer increases as the MAOMC content increases in the copolymer. This shows that coumarin moiety plays a very important role in the antibacterial activity.     

Effect of Functionalized Magnetite Nanoparticles and Diaminoxanthone on the Curing,Thermal Degradation Kinetic and Corrosion Property of Diglycidyl Ether of Bisphenol A-Based Epoxy Resin

To prepare a high-performance epoxy resin with excellent thermal, chemical and corrosion stability, diaminoxanthone（DAX） was used to cure diglycidylether of bisphenol-A（DGEBA）-based epoxy resin and blend of DGEBA with functionalized Fe3O4 nanoparticles. Kinetic parameters of curing and thermal degradation of epoxy resin systems were estimated by differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA）, respectively. The 10% weight loss temperature has been increased from 340 °C to 366 °C and there was an increase in the char yield from 32.6% to 45.3% for the above systems. The corrosion performance of epoxy coated carbon steel was examined by potentiodynamic polarization, along with immersion test in 1.0 mol/L HCl solution. The results showed that epoxy resins cured with DAX had low tendency to corrosion. In addition, the cured epoxy resin containing 10% Fe3O4 had higher anticorrosion activity than bare DGEBA system. The results showed that functionalized Fe3O4 nanoparticles enhanced char formation and improved the thermal stability as well as anticorrosion activity of the resin.     

Excellent complete conversion activity for methane and CO of Pd/TiOz-Zro.sA10.5O1.75 catalyst used in lean-bum natural gas vehicles

Palladium catalysts are supported on TiO2, ZrO2, A12O3, Zro.sAlo.501.75 and TiO2-Zro.sAlo.501.75 prepared by co-precipitation method, re- spectively. Catalytic activities for methane and CO oxidation are evaluated in a gas mixture that simulated the exhaust from lean-burn natural gas vehicles （NGVs）. Pd/TiO2-Zro.sAlo.501.75 performs the best catalytic activity among the tested five catalysts. For CH4, the light-off temperature （Tso） is 254 ℃, and the complete conversion temperature （Tgo） is 280 ℃; for CO, Tso is 84 ℃, and Tgo was 96 ℃. Various techniques, including N2 adsorption-desorption, X-ray diffraction （XRD）, H2-temperature-programmed reduction （H2-TPR）, X-ray photoelec- tron spectroscopy （XPS）, and scanning electron microscopy （SEM） are employed to characterize the effect of supports on the physicochemical properties of prepared catalysts. N2 adsorption-desorption and SEM show that TiO2-Zro.5Al0.501.75 expresses uniform nano-particles and large meso-pore diameters of 26 nm. H2-TPR and XRD indicate that PdO is well dispersed on the supports and strongly interacted with each other. The results of XPS show that the electron density around PdO and the proportion of active oxygen on TiO2-Zro.sAl0.501.75 are maxima among the five supports.     

Effect of Ni,Fe and Fe-Ni alloy catalysts on the synthesis of metal contained carbon nano-onions and studies of their electrochemical hydrogen storage properties

Three types of carbon nano-onions(CNOs) including Ni@CNOs.Fe_3C@CNOs and Fe_(0.64)Ni_(0.36)@CNOs nanoparticles have been synthesized by catalytic decomposition of methane at 850 ℃ using nickel,iron and iron-nickel alloy catalysts.Comparative and systematic studies have been carried out on the morphology,structural characteristics and graphitic crystallinity of these CNOs products.Furthermore,the electrochemical hydrogen storage properties of three types of CNOs have been investigated.Measurements show that the Ni@CNOs have the highest discharge capacity of 387.2 mAh/g,coiTesponding to a hydrogen storage of 1.42%.This comparison study shows the advantages of each catalyst in the growth of CNOs.enabling the controllable synthesis and tuning the properties of CNOs by mediating different metals and their alloy for using in the fuel cell system.     

Polyelectrolyte Multilayer Patterns Created by Capillary Force and Their Impact on Cell Migration

Cell migration plays a crucial role in a variety of physiological and pathological processes.In this study a method of capillary force lithography was used to treat poly(sodium 4-styrenesulfonate) (PSS)/poly(diallyldimethylammonium) chloride (PDADMAC) multilayers with a PDMS stamp before or after etching by NaC1 solution,yielding physical patterns with various features such as double thin lines,double strips,meniscus-shaped ridges,and high ridges.The ridge height is controllable in the range of 25 and 1100 nm.Migration of smooth muscle cells (SMCs) was restrained by the double-line patterns in a ridge height-dependent manner.By contrast,the mobility of SMCs was controlled by both the hydration ratio of the multilayers and the pattern features.     

Influence of Reverse Pressure on the Shear Viscosity of Hydrophilic Poly（ethylene terephthalate） Melt

The effect of reverse pressure.on rheological behavior has been studied. The apparatus is a capillary rheometer with counter pressure chamber being held at a high reverse pressure by means of a cock. The results show that with the increase in temperature, the shear viscosity of hydrophilic PET is reduced. It is different that the effect of temperature on shear viscosity is varied under the condition of all shear rates or all pressures, and the effect is more prominent at 50 MPa or at 216 s-1. At the same time, the pressure coefficients decrease with increasing the shear rate and the temperature and tend to reach a constant value nearly at the temperature of 290 °C.     

Selective oxidation of ethane to aldehydes over SBA-15 supported molybdenum catalyst

SBA-15 supported Mo catalysts （Moy/SBA-15） were prepared by an ultrasonic assisted incipient-wetness impregnation method. The physical and chemical properties of the catalysts were characterized by means of N2-adsorption-desorption, XRD, TEM, UV-Vis, Raman, XANES and H2-TPR. The results showed that a trace amount of MoO3 was produced on high Mo content samples. Tum-over frequency （TOF） and product selectivity are dependent on the molybdenum content. Both Mo0.75/SBA-15 and Mo1.75/SBA-15 catalysts give the higher catalytic activity and the selectivity to the total aldehydes for the selective oxidation of C2H6. At the reaction temperature of 625℃, the maximum yield of aldehydes reached 4.2% over Mo0.75/SBA-15 catalyst. The improvement of the activity and selectivity was related with the state of MoOx species.     

Preferential oxidation of CO in excess H2 over the CeO2/CuO catalyst： Effect of initial support

Three series of CeO2/CuO samples were prepared by impregnation method and characterized by XRD, N2adsorption-desorption, temperatureprogrammed reduction(TPR), XPS and TEM techniques. In comparison with the samples prepared with CuO as initial support, the samples with Cu(OH)2as initial support have higher reducibilities and smaller relative TPR peak areas, and also larger specific surface areas at calcination temperatures of 400℃–600℃. As a result, Cu(OH)2is better than CuO as initial support for preferential oxidation of CO in excess H2(CO-PROX). The best catalytic performance was achieved on the sample calcined at 600℃ and with an atomic ratio of Ce/Cu at 40%. XPS analyses indicate that more interface linkages Ce-O-Cu could be formed when it was calcined at 600℃. And the atomic ratio of Ce/Cu at 40%led to a proper reducibility for the sample as illustrated by the TPR measurements.     

Synthesis,Characterization, and Linear and Nonlinear Optical Properties of Phenylene-vinylene Based Chromophores for Singlet Oxygen Generation

A series of symmetrical and unsymmetrical phenylene-vinylene （PV） based chro- mophores with the molecular configuration of donor-π-donor （D-g-D） were prepared and characterized. Iodine was first introduced into the Jr-conjugation backbone of the PV based chromophores in order to study the heavy atom effect on their linear absorption, two-photon absorption （TPA） properties, as well as singlet oxygen generation properties. TPA cross-sections of these chromophores were investigated by using the two-photon excited fluorescence method. The unsymmetrical chromophores were found to have larger TPA cross-section values compared to their symmetrical counterparts. For one of the unsymmetrical chromophores with the iodine incorporation, a large TPA cross section value with quenched emission was found. The decreased fluorescence quantum yield of a molecule can be ascribed to the increased intersystem crossing, which is favorable for enhancing the singlet oxygen generation. Therefore, the unsymmetrical PV based chromophores with heavy atom incorporation are promising singlet oxygen sensitizers for the photodynamic therapy application.     

Improved electrochemical hydrogen storage properties of Mg-Y thin films as a function of substrate temperature

Pd-capped Mg_(78)Y_(22) thin films have been prepared by direct current magnetron co-sputtering system at different substrate temperatures and their electrochemical hydrogen storage properties have been investigated.It is found that rising substrate temperature to 60 ℃ can coarsen the surface of thin film,thus facilitating the diffusion of hydrogen atoms and then enhancing its discharge capacity to ~1725 mAh·g~(-1).Simultaneously,the cyclic stability is effectively improved due to the increased adhesion force between film and substrate as a function of temperature.In addition,the specimen exhibits a very long and flat discharge plateau at about —0.67 V,at which nearly 60%of capacity is maintained.The property is favorable for the application in metal hydride/nickel secondary batteries.The results indicate that rising optimal substrate temperature has a beneficial effect on the electrochemical hydrogen storage of Mg-Y thin films.     

Unique catalysis of Ni-Al hydrotalcite derived catalyst in CO_2 methanation: cooperative effect between Ni nanoparticles and a basic support

Ni-Al hydrotalcite derived catalyst （Ni-Al2O3-HT） exhibited a narrow Ni particle-size distribution with an average particle size of 4.0 nm. Methanation of CO2 over this catalyst initiated at 225℃ and reached 82.5% CO2 conversion with 99.5% CH4 selectivity at 350℃, which was much better than its impregnated counterpart. Characterizations by means of CO2 microcalorimetry and 27 Al NMR indicated that large amount of strong basic sites existed on Ni-Al2O3-HT, originated from the formation of Ni-O-Al structure. The existence of strong basic sites facilitated the activation of CO2 and consequently promoted the activity. The combination of highly dispersed Ni with strong basic support led to its unique and high efficiency for this reaction.

Keywords     

Hydrogen storage over alkali metal hydride and alkali metal hydroxide composites

Alkali metal hydroxide and hydride composite systems contain both protic(H bonded with O) and hydridic hydrogen. The interaction of these two types of hydrides produces hydrogen. The enthalpy of dehydrogenation increased with the increase of atomic number of alkali metals,i.e.,-23 kJ/molH2 for LiOH-LiH, 55.34 kJ/molH2 for NaOH-NaH and 222 kJ/molH2 for KOH-KH. These thermodynamic calculation results were consistent with our experimental results. H2 was released from LiOH-LiH system during ball milling. The dehydrogenation temperature of NaOH-NaH system was about 150℃; whereas KOH and KH did not interact with each other during the heating process. Instead, KH decomposed by itself. In these three systems, NaOH-NaH was the only reversible hydrogen storage system, the enthalpy of dehydrogenation was about 55.65 kJ/molH2, and the corresponding entropy was ca. 101.23 J/(molH2 K), so the temperature for releasing 1.0 bar H2 was as high as 518℃, showing unfavorable thermodynamic properties. The activation energy for hydrogen desorption of NaOH-NaH was found to be57.87 kJ/mol, showing good kinetic properties.     

Graphene Oxide Doped Poly（hydroxymethylated-3,4- ethylenedioxythiophene）： Enhanced Sensitivity for Electrochemical Determination of Rutin and Ascorbic Acid

A novel graphene oxide doped poly(hydroxymethylated-3,4-ethylenedioxythiophene)(PEDOT-MeOH/GO) composite film was synthesized and utilized as an efficient electrode material for simultaneous detection of rutin and ascorbic acid(AA). PEDOT-MeOH/GO films were synthesized on glassy carbon electrode(GCE) by a facile one-step electrochemical approach and were characterized by scanning electron microscopy, UV-Vis spectroscopy, FTIR spectra and electrochemical methods. Then the PEDOT-MeOH/GO/GCE was applied successfully in the simultaneous detection of rutin and AA. The results showed that the oxidation peak currents of rutin and AA obtained at the PEDOT-MeOH/GO/GCE were much higher than those at the traditional conducting polymer PEDOT/GO/GCE, PEDOT-MeOH/GCE, PEDOT/GCE and bare GCE. Under optimized conditions, the linear ranges for rutin and AA are 20 nmol/L-10 μmol/L and 8 μmol/L-1 mmol/L, respectively. The detection limit is 6 nmol/L for rutin and 2 μmol/L for AA(S/N = 3), which are lower than those of the reported electrochemical sensors.     

Synthesis and Self-assembly of a Linear Coil-Coil-Rod ABC Triblock Copolymer

An interesting order-order transition between two different complex nanostructures was observed in a new liquid crystalline linear coil-coil-rod ABC triblock copolymer（tri BCP）. First, the ABC tri BCP, poly（dimethylsiloxane）-bpolystyrene-b-poly{2,5-bis[（4-methoxyphenyl）oxycarbonyl]styrene}（PDMS-b-PS-b-PMPCS）, was synthesized through sequential atom transfer radical polymerization. The degrees of polymerization of PDMS, PS, and PMPCS blocks are 58, 159, and 106, and the corresponding volume fractions of PDMS, PS, and PMPCS are 0.09, 0.29, and 0.62, respectively. The phase behaviors of the PDMS-b-PS diblock copolymer precursor and the final triblock copolymer were studied by smallangle X-ray scattering, one-dimensional wide-angle X-ray scattering, and transmission electron microscopy experiments. The PDMS-b-PS precursor self-assembles into hexagonally packed cylinders with a relatively small periodic size after thermal annealing. When the triblock copolymer is annealed at a relatively low temperature（120 ○C） at which the PMPCS block is in the amorphous state, the tri BCP forms core-shell hexagonally packed cylinders（CSH） with a relativly large periodic size. After the tri BCP is annealed above 140 ○C at which the PMPCS block transforms to the liquid crystalline（LC） phase, the nanophase-separated structure transforms to a three-phase four-layer lamellar structure（LAM-3P4L）. Thus, accompanied with the transition of the PMPCS blocks from the amorphous state to the LC phase, the order-order transition from CSH to LAM-3P4 L occurs in the PDMS-b-PS-b-PMPCS ABC tri BCP.