Farnesene monomer,obtained through the bio-fermentation,offered a unique long side chain structure that served as an excellent platform for the synthesis of“bottlebrush-like”polymers with exceptional thermal propert...Farnesene monomer,obtained through the bio-fermentation,offered a unique long side chain structure that served as an excellent platform for the synthesis of“bottlebrush-like”polymers with exceptional thermal properties.Such polymers had immense potential in the production of polyurethane elastomers and adhesives.Hydroxyl-terminated polyfarnesene(PFD),which was safe,environmentally-friendly and pollution-free,was synthesized with farnesene as the monomer and industrial grade product hydrogen peroxide as the initiator by aqueous free-radical polymerization.展开更多
The interfering kinetics of the coherent synchronous reactions of hydrogen peroxide decomposition and the oxidation of pyridine derivatives have been studied experimentally. The regions of the selective oxidation of t...The interfering kinetics of the coherent synchronous reactions of hydrogen peroxide decomposition and the oxidation of pyridine derivatives have been studied experimentally. The regions of the selective oxidation of the pyridine derivatives have been found, and the optimal conditions for the production of4-vynilpyridine, 4-vynilpyridine N-monoxide, 2, 2-dipyridyl, and pyridine have been determined. The most probable synchronization mechanism is suggested for hydrogen peroxide decomposition and the free-radical chain oxidation of pyridine derivatives. The HO2 -radical plays the key role in this mechanism. The activation energies are calculated for the elementary steps of 4-ethylpyridine dehydrogenation.展开更多
An experimental study of thermal DeNOx process with different additives was performed in an electricityheated tubular flow reactor,showing that CO is less effective to lower the optimum temperature than H2 and CH4. Th...An experimental study of thermal DeNOx process with different additives was performed in an electricityheated tubular flow reactor,showing that CO is less effective to lower the optimum temperature than H2 and CH4. The maximum NO reduction is lowered with H2 added,while it is hardly affected by CO or CH4.The temperature window is widened appreciably with CH4 added,while it is narrowed slightly by H2 or CO.The disadvantage of CH4 is that it causes CO emission due to its incomplete oxidation,and the maximum conversion of CH4 to CO is more than 50%.In general,the calculation using a detailed chemical kinetic model predicts most of the process features reasonably well.The analysis on reaction mechanism shows that the effects of these additives on NO reduction are achieved principally by promoting the production of·OH radical.展开更多
Trans-sobrerol （Sob） and 8-p-menthen-1,2-diol （Limo-diol） are the primary products in the atmospheric oxidation of α-pinene and limonene, respectively. Because of their low volatility, they associate more likely ...Trans-sobrerol （Sob） and 8-p-menthen-1,2-diol （Limo-diol） are the primary products in the atmospheric oxidation of α-pinene and limonene, respectively. Because of their low volatility, they associate more likely to the liquid particles in the atmosphere, where they are subject to the aqueous phase oxidation by the atmospheric oxidants. In this work, through experimental and theoretical study, we first provide the rate constants of Sob and Limo-diol reacting with hydroxyl radical （.OH） in aqueous solution at room temperature of 3044-3 K and 1 atm pressure, which are （3.05±0.5）×10 9 and （4.57±0.2）×10 9 L/（mol.s）, respectively. Quantum chemistry calculations have also been employed to demonstrate the solvent effect on the rate constants in aqueous phase and the calculated results agree well with the measurements. Some reaction products have been identified based on liquid chromatography combined with mass spectroscopy and theoretical calculations.展开更多
A finite volume algorithm was established in order to investigate two-dimensional hydrodynamic problems. These include viscous free surface flow interaction with free rigid bodies in the case of large and/or relative ...A finite volume algorithm was established in order to investigate two-dimensional hydrodynamic problems. These include viscous free surface flow interaction with free rigid bodies in the case of large and/or relative motions. Two-phase flow with complex deformations at the interface was simulated using a fractional step-volume of fluid algorithm. In addition, body motions were captured by an overlapping mesh system. Here, flow variables are transferred using a simple fully implicit non-conservative interpolation scheme which maintains the second-order accuracy of implemented spatial discretisation. Code was developed and an appropriate set of problems investigated. Results show good potential for development of a virtual hydrodynamics laboratory.展开更多
Lactose milk sugar is found only in the milk of mammals. In order to understand the mechanism of oxidation of lactose, a systematic kinetic study of oxidation of lactose with photochemicaUy generated radicals was carr...Lactose milk sugar is found only in the milk of mammals. In order to understand the mechanism of oxidation of lactose, a systematic kinetic study of oxidation of lactose with photochemicaUy generated radicals was carried out. The reaction has a first order dependence on chloramine-T as well as on substrate. The reaction is catalysed by H＋ ions as well. On the basis of kinetic results and product analysis a probable mechanism were suggested.展开更多
Sliced velocity mapping ion imaging technique was employed to investigate the dynamics of the hydroxyl elimination channel in the photodissociaiton of nitric acid in the ultraviolet region. The OH product was detected...Sliced velocity mapping ion imaging technique was employed to investigate the dynamics of the hydroxyl elimination channel in the photodissociaiton of nitric acid in the ultraviolet region. The OH product was detected by （2＋1） resonance enhanced multiphoton ionization via the D^2∑^- electronic state. The total kinetic energy spectra of the OH＋NO2 channel from the photolysis of HONO2 show that both ：NO2（X2A1） and NO2（A2B2） channels are present, suggesting that both 1^1A″ and 2^1A″ excited electronic states of HONO2 are involved in the excitation. The parallel angular distributions suggest that the dissociation of the nitric acid is a fast process in comparison with the rotational period of the HNO3 molecule. The anisotropy parameter β for the hydroxyl elimination channel is found to be dependent on the OH product rotational state as well as the photolysis energy.展开更多
We present a theoretical study of the reaction of the hydroxyl radical with ethene using electronic structure calculations and direct-dynamics simulations. High-accuracy electronic structure calculations at the CCSD（...We present a theoretical study of the reaction of the hydroxyl radical with ethene using electronic structure calculations and direct-dynamics simulations. High-accuracy electronic structure calculations at the CCSD（T）/aug-cc-pVTZ//MP2/aug-ce-pVDZ level have been carried out to characterize the representative regions of the potential energy surface of various reaction pathways, including OH-addition and H-abstraction. These ab initio calculations have been employed to derive an improved set of parameters for the MSINDO semiempirieal Hamiltonian specific to the OH＋C2H4 reaction. The specific-reaction-parameter Hamilto- nian captures the ab initio data accurately, and has been used to perform direct quasiclassica] trajectory simulations of the OH＋C2H4 reaction at collision energies in the range of 2-10 kcal/mol. The calculated cross sections reveal that the OH-addition reaction domi- nates at all energies over H-abstraction. In addition, the excitation function of addition is reminiscent of a barrierless capture process, while that for abstraction corresponds to an activated one, and these trends can be connected to the transition-state energies of both reactions. We note that the development of an accurate semiempirical Hamiltonian for the OH＋C2H4 reaction in this work required the inclusion of empirical dispersion corrections, which will be important in future applications for which long-range intermoleeular attraction becomes significant.展开更多
Objective: Reactive oxygen species(ROS) are involved in a variety of biological phenomena and serve both deleterious and beneficial roles. ROS quantification and assessment of reaction networks are desirable but diffi...Objective: Reactive oxygen species(ROS) are involved in a variety of biological phenomena and serve both deleterious and beneficial roles. ROS quantification and assessment of reaction networks are desirable but difficult because of their short half-life and high reactivity. Here, we describe a pro-oxidative model in a single human lung carcinoma SPC-A-1 cell that was created by application of extracellular H2O2 stimuli. Methods: Modified microfluidics and imaging techniques were used to determine O2·- levels and construct an O2^·- reaction network. To elucidate the consequences of increased O2^·- input, the mitochondria were given a central role in the oxidative stress mode, by manipulating mitochondria-interrelated cytosolic Ca2+ levels, mitochondrial Ca^2+ uptake, auto-amplification of intracellular ROS and the intrinsic apoptotic pathway. Results and conclusions: Results from a modified microchip demonstrated that 1 mmol/L H·-2 O2 induced a rapid increase in cellular O2 levels(>27 vs.>406 amol in 20 min), leading to increased cellular oxidizing power(evaluated by ROS levels) and decreased reducing power(evaluated by glutathione(GSH) levels). In addition, we examined the dynamics of cytosolic Ca^2+ and mitochondrial Ca^2+ by confocal laser scanning microscopy and confirmed that Ca^2+ stores in the endoplasmic reticulum were the primary source of H2O2-induced cytosolic Ca^2+ bursts. It is clear that mitochondria have pivotal roles in determining how exogenous oxidative stress affects cell fate. The stress response involves the transfer of Ca^2+ signals between organelles,ROS auto-amplification, mitochondrial dysfunction, and a caspase-dependent apoptotic pathway.展开更多
The reaction mechanism and kinetics for the addition of hydroxyl radical （OH） to phenol have been investigated using the hybrid density functional （B3LYP） method with the 6-31＋＋G（2dp, 2dr） basis set and the co...The reaction mechanism and kinetics for the addition of hydroxyl radical （OH） to phenol have been investigated using the hybrid density functional （B3LYP） method with the 6-31＋＋G（2dp, 2dr） basis set and the complete basis set （CBS） method using APNO basis sets, respectively. The equilibrium geometries, energies, and thermodynamics properties of all the stationary points along the addition reaction pathway are calculated. The rate constants and the branching ratios of each channel are evaluated using classical transition state theory （TST） in the temperature range of 210 to 360 K, to simulate temperatures in all parts of the troposphere. The ortho addition pathway is dominant and accounts for 99.8%-96.7% of the overall adduct products from 210 to 360 K. The calculated rate constants are in good agreement with existing experimental values. The addition reaction is irreversible.展开更多
We experimentally demonstrate the chaotic generation in a figure-of-eight erbium-doped fiber laser (F8L) with an optical fiber ring (OFR). With an appropriate combination of polarization controllers, we find that the ...We experimentally demonstrate the chaotic generation in a figure-of-eight erbium-doped fiber laser (F8L) with an optical fiber ring (OFR). With an appropriate combination of polarization controllers, we find that the fiber laser exhibits period-doubling route to chaos, and the chaotic self-synchronous dynamics has a tendency to be reduced significantly. The experimental results show the tendency is related to the interference and the nonlinear phase shift of light in the optical fiber ring. Meanwhile, the chaotic dynamics is related to the polarization state and pump power.展开更多
基金Supported by National Natural Science Foundation of China(52403096).
文摘Farnesene monomer,obtained through the bio-fermentation,offered a unique long side chain structure that served as an excellent platform for the synthesis of“bottlebrush-like”polymers with exceptional thermal properties.Such polymers had immense potential in the production of polyurethane elastomers and adhesives.Hydroxyl-terminated polyfarnesene(PFD),which was safe,environmentally-friendly and pollution-free,was synthesized with farnesene as the monomer and industrial grade product hydrogen peroxide as the initiator by aqueous free-radical polymerization.
文摘The interfering kinetics of the coherent synchronous reactions of hydrogen peroxide decomposition and the oxidation of pyridine derivatives have been studied experimentally. The regions of the selective oxidation of the pyridine derivatives have been found, and the optimal conditions for the production of4-vynilpyridine, 4-vynilpyridine N-monoxide, 2, 2-dipyridyl, and pyridine have been determined. The most probable synchronization mechanism is suggested for hydrogen peroxide decomposition and the free-radical chain oxidation of pyridine derivatives. The HO2 -radical plays the key role in this mechanism. The activation energies are calculated for the elementary steps of 4-ethylpyridine dehydrogenation.
基金Supported by the State Key Development Program for Basic Research of China（2006CB200303） the National Natural Science Foundation of China （50706011） the National High Technology Research and Development Program of China（2007AA05Z337）
文摘An experimental study of thermal DeNOx process with different additives was performed in an electricityheated tubular flow reactor,showing that CO is less effective to lower the optimum temperature than H2 and CH4. The maximum NO reduction is lowered with H2 added,while it is hardly affected by CO or CH4.The temperature window is widened appreciably with CH4 added,while it is narrowed slightly by H2 or CO.The disadvantage of CH4 is that it causes CO emission due to its incomplete oxidation,and the maximum conversion of CH4 to CO is more than 50%.In general,the calculation using a detailed chemical kinetic model predicts most of the process features reasonably well.The analysis on reaction mechanism shows that the effects of these additives on NO reduction are achieved principally by promoting the production of·OH radical.
基金This work was supported by the National Natural Science Foundation of China （No.21177041 and No.21107026）, the Fundamental Research Funds for the Central Universities （No.2013ZZ0073）, and the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry.
文摘Trans-sobrerol （Sob） and 8-p-menthen-1,2-diol （Limo-diol） are the primary products in the atmospheric oxidation of α-pinene and limonene, respectively. Because of their low volatility, they associate more likely to the liquid particles in the atmosphere, where they are subject to the aqueous phase oxidation by the atmospheric oxidants. In this work, through experimental and theoretical study, we first provide the rate constants of Sob and Limo-diol reacting with hydroxyl radical （.OH） in aqueous solution at room temperature of 3044-3 K and 1 atm pressure, which are （3.05±0.5）×10 9 and （4.57±0.2）×10 9 L/（mol.s）, respectively. Quantum chemistry calculations have also been employed to demonstrate the solvent effect on the rate constants in aqueous phase and the calculated results agree well with the measurements. Some reaction products have been identified based on liquid chromatography combined with mass spectroscopy and theoretical calculations.
文摘A finite volume algorithm was established in order to investigate two-dimensional hydrodynamic problems. These include viscous free surface flow interaction with free rigid bodies in the case of large and/or relative motions. Two-phase flow with complex deformations at the interface was simulated using a fractional step-volume of fluid algorithm. In addition, body motions were captured by an overlapping mesh system. Here, flow variables are transferred using a simple fully implicit non-conservative interpolation scheme which maintains the second-order accuracy of implemented spatial discretisation. Code was developed and an appropriate set of problems investigated. Results show good potential for development of a virtual hydrodynamics laboratory.
文摘Lactose milk sugar is found only in the milk of mammals. In order to understand the mechanism of oxidation of lactose, a systematic kinetic study of oxidation of lactose with photochemicaUy generated radicals was carried out. The reaction has a first order dependence on chloramine-T as well as on substrate. The reaction is catalysed by H＋ ions as well. On the basis of kinetic results and product analysis a probable mechanism were suggested.
基金Ⅴ. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China, the Ministry of Sciences and Technology, and the Chinese Academy of Sciences.
文摘Sliced velocity mapping ion imaging technique was employed to investigate the dynamics of the hydroxyl elimination channel in the photodissociaiton of nitric acid in the ultraviolet region. The OH product was detected by （2＋1） resonance enhanced multiphoton ionization via the D^2∑^- electronic state. The total kinetic energy spectra of the OH＋NO2 channel from the photolysis of HONO2 show that both ：NO2（X2A1） and NO2（A2B2） channels are present, suggesting that both 1^1A″ and 2^1A″ excited electronic states of HONO2 are involved in the excitation. The parallel angular distributions suggest that the dissociation of the nitric acid is a fast process in comparison with the rotational period of the HNO3 molecule. The anisotropy parameter β for the hydroxyl elimination channel is found to be dependent on the OH product rotational state as well as the photolysis energy.
文摘We present a theoretical study of the reaction of the hydroxyl radical with ethene using electronic structure calculations and direct-dynamics simulations. High-accuracy electronic structure calculations at the CCSD（T）/aug-cc-pVTZ//MP2/aug-ce-pVDZ level have been carried out to characterize the representative regions of the potential energy surface of various reaction pathways, including OH-addition and H-abstraction. These ab initio calculations have been employed to derive an improved set of parameters for the MSINDO semiempirieal Hamiltonian specific to the OH＋C2H4 reaction. The specific-reaction-parameter Hamilto- nian captures the ab initio data accurately, and has been used to perform direct quasiclassica] trajectory simulations of the OH＋C2H4 reaction at collision energies in the range of 2-10 kcal/mol. The calculated cross sections reveal that the OH-addition reaction domi- nates at all energies over H-abstraction. In addition, the excitation function of addition is reminiscent of a barrierless capture process, while that for abstraction corresponds to an activated one, and these trends can be connected to the transition-state energies of both reactions. We note that the development of an accurate semiempirical Hamiltonian for the OH＋C2H4 reaction in this work required the inclusion of empirical dispersion corrections, which will be important in future applications for which long-range intermoleeular attraction becomes significant.
基金Project supported by the Zhejiang Provincial Natural Science Foundation of China(No.LY18H300002)the Medical Health Science and Technology Project of Zhejiang Provincial Health Commission(No.2019RC061/2019312897)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(Nos.Y4110212 and LY19H090001)partly by the National Natural Science Foundation of China(Nos.81372301 and 81301113)
文摘Objective: Reactive oxygen species(ROS) are involved in a variety of biological phenomena and serve both deleterious and beneficial roles. ROS quantification and assessment of reaction networks are desirable but difficult because of their short half-life and high reactivity. Here, we describe a pro-oxidative model in a single human lung carcinoma SPC-A-1 cell that was created by application of extracellular H2O2 stimuli. Methods: Modified microfluidics and imaging techniques were used to determine O2·- levels and construct an O2^·- reaction network. To elucidate the consequences of increased O2^·- input, the mitochondria were given a central role in the oxidative stress mode, by manipulating mitochondria-interrelated cytosolic Ca2+ levels, mitochondrial Ca^2+ uptake, auto-amplification of intracellular ROS and the intrinsic apoptotic pathway. Results and conclusions: Results from a modified microchip demonstrated that 1 mmol/L H·-2 O2 induced a rapid increase in cellular O2 levels(>27 vs.>406 amol in 20 min), leading to increased cellular oxidizing power(evaluated by ROS levels) and decreased reducing power(evaluated by glutathione(GSH) levels). In addition, we examined the dynamics of cytosolic Ca^2+ and mitochondrial Ca^2+ by confocal laser scanning microscopy and confirmed that Ca^2+ stores in the endoplasmic reticulum were the primary source of H2O2-induced cytosolic Ca^2+ bursts. It is clear that mitochondria have pivotal roles in determining how exogenous oxidative stress affects cell fate. The stress response involves the transfer of Ca^2+ signals between organelles,ROS auto-amplification, mitochondrial dysfunction, and a caspase-dependent apoptotic pathway.
基金supported by the National Natural Science Foundation of China (20977064)
文摘The reaction mechanism and kinetics for the addition of hydroxyl radical （OH） to phenol have been investigated using the hybrid density functional （B3LYP） method with the 6-31＋＋G（2dp, 2dr） basis set and the complete basis set （CBS） method using APNO basis sets, respectively. The equilibrium geometries, energies, and thermodynamics properties of all the stationary points along the addition reaction pathway are calculated. The rate constants and the branching ratios of each channel are evaluated using classical transition state theory （TST） in the temperature range of 210 to 360 K, to simulate temperatures in all parts of the troposphere. The ortho addition pathway is dominant and accounts for 99.8%-96.7% of the overall adduct products from 210 to 360 K. The calculated rate constants are in good agreement with existing experimental values. The addition reaction is irreversible.
基金supported by the National Natural Science Foundation of China (No.61107033)the Natural Science Foundation for Young Scientists of Shanxi Province of China (No.2008021008)
文摘We experimentally demonstrate the chaotic generation in a figure-of-eight erbium-doped fiber laser (F8L) with an optical fiber ring (OFR). With an appropriate combination of polarization controllers, we find that the fiber laser exhibits period-doubling route to chaos, and the chaotic self-synchronous dynamics has a tendency to be reduced significantly. The experimental results show the tendency is related to the interference and the nonlinear phase shift of light in the optical fiber ring. Meanwhile, the chaotic dynamics is related to the polarization state and pump power.
