We evaluated the hydroxyl and alkyl-oxy radical scavenging activity of instant coffee using an electron spin resonance （ESR） spin-trapping method, which was based the spin-trapping reagent 5-（2,2-dimethy-l,3-propox...We evaluated the hydroxyl and alkyl-oxy radical scavenging activity of instant coffee using an electron spin resonance （ESR） spin-trapping method, which was based the spin-trapping reagent 5-（2,2-dimethy-l,3-propoxycyclophosphoryl）-5-methyl-l-pyrroline N-oxide （CYPMPO）. In this method, very pure hydroxyl and alkyl-oxy radicals were generated by illuminating a phosphate buffer solution containing hydrogen peroxide and 2,2＇-azobis （2-amidinopropane） dihydrochloride with a Hg-Xe arc lamp. The ESR adduct signal was sensitive and very stable. We concluded that instant coffee has high hydroxyl radical and alkyl-oxy radical scavenging activity.展开更多
Two kinds of the phosphorus-centered radicals produced from hydrogen atomion by 2, 2-diphenyl-1-picrylhydrazyl(DPPH were trapped by N-tert-butyl-α-phenylnitrone(PBN) and 5, 5-dimethyl-1-pyrroline N-oxide (DMPO), and ...Two kinds of the phosphorus-centered radicals produced from hydrogen atomion by 2, 2-diphenyl-1-picrylhydrazyl(DPPH were trapped by N-tert-butyl-α-phenylnitrone(PBN) and 5, 5-dimethyl-1-pyrroline N-oxide (DMPO), and investigated by means of EPR spectroscopy. The spin adducts with a characteristic hyperfine coupling constant(hfcc) caused by a phosphorus atom were observed. Based on the hfcc values caused by the phosphorus and hydrogen atoms, the con formational positions of the adducts trapped by PBN and DMPO are discussed.展开更多
Oxidation of fats and oils during storage causes their degradation and loss of nutritional value and appearance. Electron spin resonance （ESR） is the only method that can be used to directly observe the radicals. In...Oxidation of fats and oils during storage causes their degradation and loss of nutritional value and appearance. Electron spin resonance （ESR） is the only method that can be used to directly observe the radicals. In this study, the authors used an ESR spin-trapping method to study the oxidation of triacylglycerols （TAG） containing different fatty acids （FAs） commonly found in food. The ESR adduct signals were analyzed to study the effect of double bonds and the chain length of the FAs of TAG on oxidation. Oxidation was conducted by applying UV irradiation to TAG by dissolving it in N-tert-buthyl〈t-phenylnitrone （PBN）, which trapped the radicals induced in the TAG as an ESR adduct signal. The detection was clearly successful. There were no differences in the spectra of tristearin （18：0） and tripalmitin （16：0）; thus, it can be concluded that the length of the carbon chain of the FAs of TAG does not affect the oxidation reactions. However, the ESR spectra of tristearin （18：0）, triolein （18：1） and trilinolein （18：3） were clearly different due to the presence/absence of a new peak corresponding to new induced radicals, leading to the conclusion that double bonds play a major role in the oxidation reactions of fats and oils.展开更多
Ⅰ. INTRODUCTIONIn our previous studies the cleavage reaction of Co—C bond of RCo（Salen） L [Salen=bis （salicyladehyde）ethylenediamine, L= H<sub>2</sub>O or without H<sub>2</sub>O, R= CH<...Ⅰ. INTRODUCTIONIn our previous studies the cleavage reaction of Co—C bond of RCo（Salen） L [Salen=bis （salicyladehyde）ethylenediamine, L= H<sub>2</sub>O or without H<sub>2</sub>O, R= CH<sub>3</sub>·, C<sub>2</sub>H<sub>5</sub>·, n-and i-C<sub>3</sub>H<sub>7</sub>·, n-, i- and t-C<sub>4</sub>H<sub>9</sub>·] in methanol on photolysis or thermolysis was obtained:展开更多
Hyperfine interaction between electron spin and randomly oriented nuclear spins is a key issue of electron coherence for quantum information/computation. We propose an efficient way to establish high polarization of n...Hyperfine interaction between electron spin and randomly oriented nuclear spins is a key issue of electron coherence for quantum information/computation. We propose an efficient way to establish high polarization of nuclear spins and reduce the intrinsic nuclear spin fluctuations. Here, we polarize the nuclear spins in semiconductor quantum dot(QD) by the coherent population trapping(CPT) and the electric dipole spin resonance(EDSR) induced by optical fields and ac electric fields. By tuning the optical fields, we can obtain a powerful cooling background based on CPT for nuclear spin polarization. The EDSR can enhance the spin flip–flop rate which may increase the cooling efficiency. With the help of CPT and EDSR, an enhancement of 1300 times of the electron coherence time can be obtained after a 10-ns preparation time.展开更多
The gaseous photochemical reaction of n-pentane and sulfur dioxide was studied.A series of gaseous products such as alcohols, ketones, acids, esters and inorganic compound were identified by GC/MS and GC. According to...The gaseous photochemical reaction of n-pentane and sulfur dioxide was studied.A series of gaseous products such as alcohols, ketones, acids, esters and inorganic compound were identified by GC/MS and GC. According to the characters of the compounds and the free radical theory, the free radical mechanism of this gaseous photochemical reaction was suggested. The free radical mechanism was verified directly by means of the gaseous free radicals measured by spin trapping-ESR methods in which PBN was selected as the spintrap.展开更多
The synthesis of a novel α phosphorus containing spin trap, DEPDMPO(5 diethoxy Phosphoryl 2, 5 dimethyl 1 pyrroline \%N\% oxide) and the evaluation of its ability to spin trap the hydroxyl and the superoxide anion ra...The synthesis of a novel α phosphorus containing spin trap, DEPDMPO(5 diethoxy Phosphoryl 2, 5 dimethyl 1 pyrroline \%N\% oxide) and the evaluation of its ability to spin trap the hydroxyl and the superoxide anion radicals were described in the present article. The ability to trap an active superoxide anion radical generated in the photo system Ⅱ(PSII) and the stability of their spin adduct of DEPDMPO as well as three previously reported traps DMPO, DEPMPO and M 3PO were comparatively analyzed according to their chemical structures. In addition, the effects of 2 methyl and \%α\% phosphoryl substituted analogues of DMPO on the stabilities of the corresponding spin adduts were systematically展开更多
Synthesis of a novel α phosphorus containing spin trap, DEPPEPO[5 (diethoxyphosphoryl) 5 phenylethyl 1 pyrroline] N oxide and evaluation of its ability to spin trap the hydroxyl and the superoxide anion radicals were...Synthesis of a novel α phosphorus containing spin trap, DEPPEPO[5 (diethoxyphosphoryl) 5 phenylethyl 1 pyrroline] N oxide and evaluation of its ability to spin trap the hydroxyl and the superoxide anion radicals were described in the present article. The ability for trapping an active superoxide anion radicals generated in the HX/XO system and the stability of their spin adduct of DEPPEPO were analyzed. In addition, the effects of 5 phenylethyl and 5 phenyl substituted analogues of DMPO on the stereochemistry of the corresponding spin adducts were systematically illustrated.展开更多
文摘We evaluated the hydroxyl and alkyl-oxy radical scavenging activity of instant coffee using an electron spin resonance （ESR） spin-trapping method, which was based the spin-trapping reagent 5-（2,2-dimethy-l,3-propoxycyclophosphoryl）-5-methyl-l-pyrroline N-oxide （CYPMPO）. In this method, very pure hydroxyl and alkyl-oxy radicals were generated by illuminating a phosphate buffer solution containing hydrogen peroxide and 2,2＇-azobis （2-amidinopropane） dihydrochloride with a Hg-Xe arc lamp. The ESR adduct signal was sensitive and very stable. We concluded that instant coffee has high hydroxyl radical and alkyl-oxy radical scavenging activity.
文摘Two kinds of the phosphorus-centered radicals produced from hydrogen atomion by 2, 2-diphenyl-1-picrylhydrazyl(DPPH were trapped by N-tert-butyl-α-phenylnitrone(PBN) and 5, 5-dimethyl-1-pyrroline N-oxide (DMPO), and investigated by means of EPR spectroscopy. The spin adducts with a characteristic hyperfine coupling constant(hfcc) caused by a phosphorus atom were observed. Based on the hfcc values caused by the phosphorus and hydrogen atoms, the con formational positions of the adducts trapped by PBN and DMPO are discussed.
文摘Oxidation of fats and oils during storage causes their degradation and loss of nutritional value and appearance. Electron spin resonance （ESR） is the only method that can be used to directly observe the radicals. In this study, the authors used an ESR spin-trapping method to study the oxidation of triacylglycerols （TAG） containing different fatty acids （FAs） commonly found in food. The ESR adduct signals were analyzed to study the effect of double bonds and the chain length of the FAs of TAG on oxidation. Oxidation was conducted by applying UV irradiation to TAG by dissolving it in N-tert-buthyl〈t-phenylnitrone （PBN）, which trapped the radicals induced in the TAG as an ESR adduct signal. The detection was clearly successful. There were no differences in the spectra of tristearin （18：0） and tripalmitin （16：0）; thus, it can be concluded that the length of the carbon chain of the FAs of TAG does not affect the oxidation reactions. However, the ESR spectra of tristearin （18：0）, triolein （18：1） and trilinolein （18：3） were clearly different due to the presence/absence of a new peak corresponding to new induced radicals, leading to the conclusion that double bonds play a major role in the oxidation reactions of fats and oils.
基金Project supported by the National Natural Science Foundation of China.
文摘Ⅰ. INTRODUCTIONIn our previous studies the cleavage reaction of Co—C bond of RCo（Salen） L [Salen=bis （salicyladehyde）ethylenediamine, L= H<sub>2</sub>O or without H<sub>2</sub>O, R= CH<sub>3</sub>·, C<sub>2</sub>H<sub>5</sub>·, n-and i-C<sub>3</sub>H<sub>7</sub>·, n-, i- and t-C<sub>4</sub>H<sub>9</sub>·] in methanol on photolysis or thermolysis was obtained:
基金partially supported by the National Natural Science Foundations of China(Grant Nos.11374039 and 11174042)the National Basic Research Program of China(Grant Nos.2011CB922204 and 2013CB632805)
文摘Hyperfine interaction between electron spin and randomly oriented nuclear spins is a key issue of electron coherence for quantum information/computation. We propose an efficient way to establish high polarization of nuclear spins and reduce the intrinsic nuclear spin fluctuations. Here, we polarize the nuclear spins in semiconductor quantum dot(QD) by the coherent population trapping(CPT) and the electric dipole spin resonance(EDSR) induced by optical fields and ac electric fields. By tuning the optical fields, we can obtain a powerful cooling background based on CPT for nuclear spin polarization. The EDSR can enhance the spin flip–flop rate which may increase the cooling efficiency. With the help of CPT and EDSR, an enhancement of 1300 times of the electron coherence time can be obtained after a 10-ns preparation time.
文摘The gaseous photochemical reaction of n-pentane and sulfur dioxide was studied.A series of gaseous products such as alcohols, ketones, acids, esters and inorganic compound were identified by GC/MS and GC. According to the characters of the compounds and the free radical theory, the free radical mechanism of this gaseous photochemical reaction was suggested. The free radical mechanism was verified directly by means of the gaseous free radicals measured by spin trapping-ESR methods in which PBN was selected as the spintrap.
文摘The synthesis of a novel α phosphorus containing spin trap, DEPDMPO(5 diethoxy Phosphoryl 2, 5 dimethyl 1 pyrroline \%N\% oxide) and the evaluation of its ability to spin trap the hydroxyl and the superoxide anion radicals were described in the present article. The ability to trap an active superoxide anion radical generated in the photo system Ⅱ(PSII) and the stability of their spin adduct of DEPDMPO as well as three previously reported traps DMPO, DEPMPO and M 3PO were comparatively analyzed according to their chemical structures. In addition, the effects of 2 methyl and \%α\% phosphoryl substituted analogues of DMPO on the stabilities of the corresponding spin adduts were systematically
文摘Synthesis of a novel α phosphorus containing spin trap, DEPPEPO[5 (diethoxyphosphoryl) 5 phenylethyl 1 pyrroline] N oxide and evaluation of its ability to spin trap the hydroxyl and the superoxide anion radicals were described in the present article. The ability for trapping an active superoxide anion radicals generated in the HX/XO system and the stability of their spin adduct of DEPPEPO were analyzed. In addition, the effects of 5 phenylethyl and 5 phenyl substituted analogues of DMPO on the stereochemistry of the corresponding spin adducts were systematically illustrated.
