ESR saturation power point of the hair of healthy, lung cancer, esophageal cancer, as well as silicosis, tuberculosis and cardiovascular disease were detected. The results show that the positive rate is 1.69%, 85.42%,...ESR saturation power point of the hair of healthy, lung cancer, esophageal cancer, as well as silicosis, tuberculosis and cardiovascular disease were detected. The results show that the positive rate is 1.69%, 85.42%, 90.4%, 20.00%, 27.27% and 0% respectively. There is a significant difference between lung cancer, esophageal cancer and healthy persons (P<0. 001). ESR saturation power point elevates sharply after treatment of lung cancer, 71. 43% of total cases ranged from 7. 9 to 24. 0 (mW), after treatment of esophageal cancer, 71. 23% ranged from 7.9 to 19.9 (mW). All patients with cardiovascular disease were examined to be negative, i. e. , above 10. 0 (mW).展开更多
We have performed magnetization measurements and electron spin resonance （ESR） on polycrystalline manganites of Nd0.5Sr0.5-xBaxMnO3 （x = 0.1）. Phase separation and phase transitions are observed from the susceptib...We have performed magnetization measurements and electron spin resonance （ESR） on polycrystalline manganites of Nd0.5Sr0.5-xBaxMnO3 （x = 0.1）. Phase separation and phase transitions are observed from the susceptibility and the ESR spectra data. Between 260 K （～ Tc） and 185 K （～ TN）, the system coexists of the paramagnetic phase and the ferromagnetic （FM） phase. Between 185 K and 140 K, the system coexists of the FM phase and the antiferromagnetic （AFM） phase. These results indicate that the system has a very complex magnetic state due to the origin of the instability stemming from manganite Nd0.5Sr0.4Ba0.1MnO3 by partially substituting the larger Ba^2＋ ions for the smaller Sr^2＋ ions.展开更多
There is evidence showing that increased levels of oxidative stress and C-reactive protein (CRP) might be associated with obesity, hypertension, atherosclerosis and other cardiovascular diseases. This study was undert...There is evidence showing that increased levels of oxidative stress and C-reactive protein (CRP) might be associated with obesity, hypertension, atherosclerosis and other cardiovascular diseases. This study was undertaken to investigate possible relationships among plasma 8-iso-prostaglandin F2α (8-iso-PG F2α: an index of oxidative stress), high-sensitivity (hs)-CRP and membrane fluidity (a reciprocal value of microviscosity) in hypertensive and normotensive men using an electron spin resonance (ESR)-method. The order parameter (S) for the spin-label agents (5-nitroxide stearate) of red blood cell (RBC) membranes in the ESR spectra was significantly higher in hypertensive men than in normotensive men, indicating that membrane fluidity was decreased in hypertensive men. Both plasma 8-iso-PG F2α and hs-CRP levels were significantly increased in hypertensive men compared with normotensive men. In addition, plasma plasma 8-iso-PG F2α levels were correlated with plasma hs-CRP levels. In contrast, plasma nitric oxide (NO)-metabolites were lower in hypertensive men than in normotensive men, and inversely correlated with plasma 8-iso-PG F2α and hs-CRP. The order parameter(S) of RBCs was correlated with plasma 8-iso-PG F2α and plasma hs-CRP, and inversely correlated with plasma NO-metabolites, suggesting that reduced membrane fluidity of RBCs might be associated with increased oxidative stress, inflammation and endothelial dysfunction. Multivariate regression analysis also showed that, after adjusting for general risk factors, both plasma 8-iso-PG F2α and hs-CRP were significant determinants of membrane fluidity of RBCs. The ESR suggests that associations of oxidative stress and inflammation might have a close correlation with impaired rheologic behavior of RBCs and microcirculatory dysfunction in hypertensive men.展开更多
Magnetic properties of single-crystalline preferential {001}-oriented Bi2Fe4O9nanosheets with thickness of about 13 nm, synthesized via a facile hydrothermal method, have been investigated through variable temperature...Magnetic properties of single-crystalline preferential {001}-oriented Bi2Fe4O9nanosheets with thickness of about 13 nm, synthesized via a facile hydrothermal method, have been investigated through variable temperature electron spin resonance measurement. A typical ferromagnetic state could be appeared in the measured temperature from 110 K to 300 K and the origin would be contributed to uncompensated surface spin due to its large surface-to-volume ratio and/or a few non-detectable impurities with strong magnetism. Interestingly, another weak ferromagnetic state could present below the temperature about 250 K, indicative of Neel temperature (TN) of antiferromagnetic state, which is slightly lower than that of bulksample of 265 K.展开更多
The effect of Eu3＋ ion doping in the La sites of single-crystal La4/3Srs/3Mn2O7 was investigated. Electron spin resonance （ESR） was applied to La4/3Sr5/3Mn2O7 and （Lao.8Euo.2）4/3Sr5/3Mn2O7 single crystals. A phas...The effect of Eu3＋ ion doping in the La sites of single-crystal La4/3Srs/3Mn2O7 was investigated. Electron spin resonance （ESR） was applied to La4/3Sr5/3Mn2O7 and （Lao.8Euo.2）4/3Sr5/3Mn2O7 single crystals. A phase separation and phase transitions were observed from the ESR spectra data. Between 350 K and 300 K, both paramagnetic resonance （PMR） and anisotropic ferromagnetic resonance （FMR） lines were observed in the ab plane and the c axis direction, suggesting a coexistence of the paramagnetic （PM） phase and the ferromagnetic （FM） phase. The magnetization measurement reveals a spin-glass-like behavior in single-crystal （Lao.8Euo.2）4/3 Sr5/3Mn2O7 below the temperature of spin freezing Tf （- 29.5 K）.展开更多
A Fe doped rutile TiO2 single crystal is grown in an O2 atmosphere by the floating zone technique. Electron spin resonance （ESR） spectra clearly demonstrate that Fe^3＋ ions are substituted for the Ti^4＋ ions in th...A Fe doped rutile TiO2 single crystal is grown in an O2 atmosphere by the floating zone technique. Electron spin resonance （ESR） spectra clearly demonstrate that Fe^3＋ ions are substituted for the Ti^4＋ ions in the rutile TiO2 matrix. Magnetization measurements reveal that the Fe：TiO2 crystal shows paramagnetic behaviour in a temperature range from 5 K to 350 K. The Fe^3＋ ions possess weak magnetic anisotropy with an easy axis along the c axis. The annealed Fe：TiO2 crystal shows spin-glass-like behaviours due to the aggregation of the ferromagnetic clusters.展开更多
Hyperhomocysteinemia and oxidative stress may be strongly linked to hypertension, atherosclerosis and other cardiovascular diseases. The present study was performed to investigate possible relationships among plasma t...Hyperhomocysteinemia and oxidative stress may be strongly linked to hypertension, atherosclerosis and other cardiovascular diseases. The present study was performed to investigate possible relationships among plasma total homocysteine, plasma 8-iso-prostaglandin F2α (8-isoPG F2α: an index of oxidative stress), and membrane fluidity (a reciprocal value of membrane microviscosity) in hypertension. We measured the membrane fluidity of red blood cells (RBCs) in hypertensive and normotensive men using an electron spin resonance (ESR) and spin-labeling method. Membrane fluidity of RBCs was significantly decreased in hypertensive men compared with normotensive men. Plasma total homocysteine levels were significantly higher in hypertensive men than in normotensive men, and correlated with plasma 8-isoPG F2α. In contrast, plasma nitric oxide (NO)-metabolites (an index of endothelial function) were lower in hypertensive men than in normotensive men. The reduced membrane fluidity of RBCs was associated with increased total homocysteine and plasma 8-isoPG F2α levels and decreased plasma NO-metabolite levels. Multivariate regression analysis showed that, after adjusting for general risk factors, plasma total homocysteine and 8-isoPG F2α were significant determinants of membrane fluidity of RBCs, respectively. These results suggest that hyperhomocysteinemia and oxidative stress with endothelial dysfunction might have a close correlation with impaired rheologic behavior of RBCs and circulatory disorders in hypertensive men.展开更多
Site-directed spin-labeling with continuous wave electron paramagnetic resonance spectroscopy was used to monitor autoproteolysis of HIV-1 protease, an enzyme essential for viral maturation. Two protein constructs wer...Site-directed spin-labeling with continuous wave electron paramagnetic resonance spectroscopy was used to monitor autoproteolysis of HIV-1 protease, an enzyme essential for viral maturation. Two protein constructs were examined, namely subtype F and the circulating recombinant form CRF01_A/E. As the protease undergoes self-cleavage, protein unfolds and small peptide fragments containing the spin label are generated, which collectively give rise to a sharp spectral component that is easily discernable in the high-field resonance line in the EPR spectrum. By monitoring the intensity of this spectral component over time, the autoproteolytic stability of each construct was characterized under various conditions. Data were collected for samples stored at 4 °C, 25 °C, and 37 °C, and on a subtype F HIV-1 protease sample stored at 25 °C and containing the FDA-approved protease inhibitor Tipranavir. As expected, the rate of autoproteolysis decreased as the storage temperature was lowered. Minimal autoproteolysis was seen for the sample that contained Tipranavir, providing direction for future spectroscopic studies of active protease samples. When compared to standard methods of monitoring protein degradation such as gel electrophoresis or chromatographic analyses, spin-labeling with CW EPR offers a facile, real-time, non-consuming way to monitor autoproteolysis or protein degradation. Additionally, mass spectrometry studies revealed that the N-termini of both constructs are sensitive to degradation and that the sites of specific autoproteolysis vary.展开更多
The present paper reviews new findings in redoxproperties of the active constituent of Chinese herbalmedicine(CHM),a kind of CHM or a compoundprescription as an antioxidant.Firstly,we have studiedtheir antioxidant and...The present paper reviews new findings in redoxproperties of the active constituent of Chinese herbalmedicine(CHM),a kind of CHM or a compoundprescription as an antioxidant.Firstly,we have studiedtheir antioxidant and prooxidant actions with electronspin resonance(ESR).The results show that the activecomponents from over 10 kinds of CHM are able toscavenge the oxygen free radicals but propyl gallate展开更多
A long life election spin resonance (ESR) signal at g=2.0006 was observed in the normal lens epithelium and cortical fibers. During ultraviolet (UV) exposure, a new ESR signal at g = 2.0060 was found in the lens epith...A long life election spin resonance (ESR) signal at g=2.0006 was observed in the normal lens epithelium and cortical fibers. During ultraviolet (UV) exposure, a new ESR signal at g = 2.0060 was found in the lens epithelium. But this specific signal was not detected in the lens cortical fibers. This suggested that lens epithelial cells were more susceptible to the free radical formation which was induced by UV light. By means of ESR spin probe oxymetry, the oxygen uptake of lens epithelial cells was meas...展开更多
This brief review highlights the techniques and diverse applications of time-resolved electron paramagnetic resonance(TREPR)spectroscopy,underscoring its essential role in elucidating the structures,spin dynamics,and ...This brief review highlights the techniques and diverse applications of time-resolved electron paramagnetic resonance(TREPR)spectroscopy,underscoring its essential role in elucidating the structures,spin dynamics,and reactivities of open-shell systems.Furthermore,we discuss the limitations of traditional TREPR methodologies,particularly their challenges in directly observing reactive radical intermediates under real-world reaction conditions.Lastly,we present the latest advancements in TREPR technology developed in our laboratory,specifically ultrawide single-sideband phase-sensitive detection(U-PSD)TREPR,highlighting its significant impact and tremendous potential in advancing free radical chemistry research.We envision promising future applications of TREPR and its pivotal role in enhancing our understanding of mechanisms involved in complex radical processes and photocatalysis.展开更多
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
This paper introduces a new method for a formula for electron spin relaxation time of a system of electrons interacting with phonons through phonon-modulated spin-orbit coupling using the projection-reduction method. ...This paper introduces a new method for a formula for electron spin relaxation time of a system of electrons interacting with phonons through phonon-modulated spin-orbit coupling using the projection-reduction method. The phonon absorption and emission processes as well as the photon absorption and emission processes in all electron transition processes can be explained in an organized manner, and the result can be represented in a diagram that can provide intuition for the quantum dynamics of electrons in a solid. The temperature （T） dependence of electron spin relaxation times （T1） in silicon is T1 ∝ T-1.07 at low temperatures and T1 ∝ T-3.3 at high temperatures for acoustic deformation constant Pad = 1.4 × 10^7 eV and optical deformation constant Pod = 4.0 × 10^17 eV/m. This means that electrons are scattered by the acoustic deformation phonons at low temperatures and optical deformation phonons at high temperatures, respectively. The magnetic field （B） dependence of the relaxation times is T1 ∝ B-2.7 at 100 K and T1 ∝ B-2.3 at 150 K, which nearly agree with the result of Yafet, T1 ∝ B-3.0- B -2.5.展开更多
The influence of a Co or phthalocyanine (Pc) molecular overlayer on the properties of quantum-well resonances (QWR) in Cu layers atop Co(001) is studied by means of spin-polarized electron reflection. For Co atoms and...The influence of a Co or phthalocyanine (Pc) molecular overlayer on the properties of quantum-well resonances (QWR) in Cu layers atop Co(001) is studied by means of spin-polarized electron reflection. For Co atoms and Pc molecules, an energy shift of the QWR-induced signal is observed with increasing coverage and is attributed to a variation of the electron reflection phase at the Cu/Co and Cu/Pc interface. For Co we find a linear energy shift in the Cu QWR energy position with increasing coverage down to the sub-monolayer regime. This shows that the phase accumulation model remains accurate within the sub-monolayer regime of a discontinuous interface. An opposite sign in the energy shift between Co and Pc overlayers could reflect an opposite impact on the Cu surface work function of overlayer adsorption.展开更多
文摘ESR saturation power point of the hair of healthy, lung cancer, esophageal cancer, as well as silicosis, tuberculosis and cardiovascular disease were detected. The results show that the positive rate is 1.69%, 85.42%, 90.4%, 20.00%, 27.27% and 0% respectively. There is a significant difference between lung cancer, esophageal cancer and healthy persons (P<0. 001). ESR saturation power point elevates sharply after treatment of lung cancer, 71. 43% of total cases ranged from 7. 9 to 24. 0 (mW), after treatment of esophageal cancer, 71. 23% ranged from 7.9 to 19.9 (mW). All patients with cardiovascular disease were examined to be negative, i. e. , above 10. 0 (mW).
基金supported by the National Natural Science Foundation of China (Grant No 50672126)the Inner Mongolia Natural Science Foundation of China (Grant No 200607010102)
文摘We have performed magnetization measurements and electron spin resonance （ESR） on polycrystalline manganites of Nd0.5Sr0.5-xBaxMnO3 （x = 0.1）. Phase separation and phase transitions are observed from the susceptibility and the ESR spectra data. Between 260 K （～ Tc） and 185 K （～ TN）, the system coexists of the paramagnetic phase and the ferromagnetic （FM） phase. Between 185 K and 140 K, the system coexists of the FM phase and the antiferromagnetic （AFM） phase. These results indicate that the system has a very complex magnetic state due to the origin of the instability stemming from manganite Nd0.5Sr0.4Ba0.1MnO3 by partially substituting the larger Ba^2＋ ions for the smaller Sr^2＋ ions.
文摘There is evidence showing that increased levels of oxidative stress and C-reactive protein (CRP) might be associated with obesity, hypertension, atherosclerosis and other cardiovascular diseases. This study was undertaken to investigate possible relationships among plasma 8-iso-prostaglandin F2α (8-iso-PG F2α: an index of oxidative stress), high-sensitivity (hs)-CRP and membrane fluidity (a reciprocal value of microviscosity) in hypertensive and normotensive men using an electron spin resonance (ESR)-method. The order parameter (S) for the spin-label agents (5-nitroxide stearate) of red blood cell (RBC) membranes in the ESR spectra was significantly higher in hypertensive men than in normotensive men, indicating that membrane fluidity was decreased in hypertensive men. Both plasma 8-iso-PG F2α and hs-CRP levels were significantly increased in hypertensive men compared with normotensive men. In addition, plasma plasma 8-iso-PG F2α levels were correlated with plasma hs-CRP levels. In contrast, plasma nitric oxide (NO)-metabolites were lower in hypertensive men than in normotensive men, and inversely correlated with plasma 8-iso-PG F2α and hs-CRP. The order parameter(S) of RBCs was correlated with plasma 8-iso-PG F2α and plasma hs-CRP, and inversely correlated with plasma NO-metabolites, suggesting that reduced membrane fluidity of RBCs might be associated with increased oxidative stress, inflammation and endothelial dysfunction. Multivariate regression analysis also showed that, after adjusting for general risk factors, both plasma 8-iso-PG F2α and hs-CRP were significant determinants of membrane fluidity of RBCs. The ESR suggests that associations of oxidative stress and inflammation might have a close correlation with impaired rheologic behavior of RBCs and microcirculatory dysfunction in hypertensive men.
文摘Magnetic properties of single-crystalline preferential {001}-oriented Bi2Fe4O9nanosheets with thickness of about 13 nm, synthesized via a facile hydrothermal method, have been investigated through variable temperature electron spin resonance measurement. A typical ferromagnetic state could be appeared in the measured temperature from 110 K to 300 K and the origin would be contributed to uncompensated surface spin due to its large surface-to-volume ratio and/or a few non-detectable impurities with strong magnetism. Interestingly, another weak ferromagnetic state could present below the temperature about 250 K, indicative of Neel temperature (TN) of antiferromagnetic state, which is slightly lower than that of bulksample of 265 K.
基金supported by the National Natural Science Foundation of China(Grant Nos.11164019 and 11064008)the Inner Mongolia Natural ScienceFoundation,China(Grant Nos.NJZZ11166,NJZY10163,NJZY12202,2011MS0101,2011MS0108,and 2009MS0101)
文摘The effect of Eu3＋ ion doping in the La sites of single-crystal La4/3Srs/3Mn2O7 was investigated. Electron spin resonance （ESR） was applied to La4/3Sr5/3Mn2O7 and （Lao.8Euo.2）4/3Sr5/3Mn2O7 single crystals. A phase separation and phase transitions were observed from the ESR spectra data. Between 350 K and 300 K, both paramagnetic resonance （PMR） and anisotropic ferromagnetic resonance （FMR） lines were observed in the ab plane and the c axis direction, suggesting a coexistence of the paramagnetic （PM） phase and the ferromagnetic （FM） phase. The magnetization measurement reveals a spin-glass-like behavior in single-crystal （Lao.8Euo.2）4/3 Sr5/3Mn2O7 below the temperature of spin freezing Tf （- 29.5 K）.
基金supported by the National Basic Research Program of China (Grant No 2009CB929201)the National Natural Science Foundation of China (Grant No 10774179)
文摘A Fe doped rutile TiO2 single crystal is grown in an O2 atmosphere by the floating zone technique. Electron spin resonance （ESR） spectra clearly demonstrate that Fe^3＋ ions are substituted for the Ti^4＋ ions in the rutile TiO2 matrix. Magnetization measurements reveal that the Fe：TiO2 crystal shows paramagnetic behaviour in a temperature range from 5 K to 350 K. The Fe^3＋ ions possess weak magnetic anisotropy with an easy axis along the c axis. The annealed Fe：TiO2 crystal shows spin-glass-like behaviours due to the aggregation of the ferromagnetic clusters.
文摘Hyperhomocysteinemia and oxidative stress may be strongly linked to hypertension, atherosclerosis and other cardiovascular diseases. The present study was performed to investigate possible relationships among plasma total homocysteine, plasma 8-iso-prostaglandin F2α (8-isoPG F2α: an index of oxidative stress), and membrane fluidity (a reciprocal value of membrane microviscosity) in hypertension. We measured the membrane fluidity of red blood cells (RBCs) in hypertensive and normotensive men using an electron spin resonance (ESR) and spin-labeling method. Membrane fluidity of RBCs was significantly decreased in hypertensive men compared with normotensive men. Plasma total homocysteine levels were significantly higher in hypertensive men than in normotensive men, and correlated with plasma 8-isoPG F2α. In contrast, plasma nitric oxide (NO)-metabolites (an index of endothelial function) were lower in hypertensive men than in normotensive men. The reduced membrane fluidity of RBCs was associated with increased total homocysteine and plasma 8-isoPG F2α levels and decreased plasma NO-metabolite levels. Multivariate regression analysis showed that, after adjusting for general risk factors, plasma total homocysteine and 8-isoPG F2α were significant determinants of membrane fluidity of RBCs, respectively. These results suggest that hyperhomocysteinemia and oxidative stress with endothelial dysfunction might have a close correlation with impaired rheologic behavior of RBCs and circulatory disorders in hypertensive men.
文摘Site-directed spin-labeling with continuous wave electron paramagnetic resonance spectroscopy was used to monitor autoproteolysis of HIV-1 protease, an enzyme essential for viral maturation. Two protein constructs were examined, namely subtype F and the circulating recombinant form CRF01_A/E. As the protease undergoes self-cleavage, protein unfolds and small peptide fragments containing the spin label are generated, which collectively give rise to a sharp spectral component that is easily discernable in the high-field resonance line in the EPR spectrum. By monitoring the intensity of this spectral component over time, the autoproteolytic stability of each construct was characterized under various conditions. Data were collected for samples stored at 4 °C, 25 °C, and 37 °C, and on a subtype F HIV-1 protease sample stored at 25 °C and containing the FDA-approved protease inhibitor Tipranavir. As expected, the rate of autoproteolysis decreased as the storage temperature was lowered. Minimal autoproteolysis was seen for the sample that contained Tipranavir, providing direction for future spectroscopic studies of active protease samples. When compared to standard methods of monitoring protein degradation such as gel electrophoresis or chromatographic analyses, spin-labeling with CW EPR offers a facile, real-time, non-consuming way to monitor autoproteolysis or protein degradation. Additionally, mass spectrometry studies revealed that the N-termini of both constructs are sensitive to degradation and that the sites of specific autoproteolysis vary.
文摘The present paper reviews new findings in redoxproperties of the active constituent of Chinese herbalmedicine(CHM),a kind of CHM or a compoundprescription as an antioxidant.Firstly,we have studiedtheir antioxidant and prooxidant actions with electronspin resonance(ESR).The results show that the activecomponents from over 10 kinds of CHM are able toscavenge the oxygen free radicals but propyl gallate
基金The work was sponsored by National Natural Science Foundation of China (NSFC)
文摘A long life election spin resonance (ESR) signal at g=2.0006 was observed in the normal lens epithelium and cortical fibers. During ultraviolet (UV) exposure, a new ESR signal at g = 2.0060 was found in the lens epithelium. But this specific signal was not detected in the lens cortical fibers. This suggested that lens epithelial cells were more susceptible to the free radical formation which was induced by UV light. By means of ESR spin probe oxymetry, the oxygen uptake of lens epithelial cells was meas...
基金supported by the Tsinghua University Dushi Program,China(No.52308013422).
文摘This brief review highlights the techniques and diverse applications of time-resolved electron paramagnetic resonance(TREPR)spectroscopy,underscoring its essential role in elucidating the structures,spin dynamics,and reactivities of open-shell systems.Furthermore,we discuss the limitations of traditional TREPR methodologies,particularly their challenges in directly observing reactive radical intermediates under real-world reaction conditions.Lastly,we present the latest advancements in TREPR technology developed in our laboratory,specifically ultrawide single-sideband phase-sensitive detection(U-PSD)TREPR,highlighting its significant impact and tremendous potential in advancing free radical chemistry research.We envision promising future applications of TREPR and its pivotal role in enhancing our understanding of mechanisms involved in complex radical processes and photocatalysis.
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This paper introduces a new method for a formula for electron spin relaxation time of a system of electrons interacting with phonons through phonon-modulated spin-orbit coupling using the projection-reduction method. The phonon absorption and emission processes as well as the photon absorption and emission processes in all electron transition processes can be explained in an organized manner, and the result can be represented in a diagram that can provide intuition for the quantum dynamics of electrons in a solid. The temperature （T） dependence of electron spin relaxation times （T1） in silicon is T1 ∝ T-1.07 at low temperatures and T1 ∝ T-3.3 at high temperatures for acoustic deformation constant Pad = 1.4 × 10^7 eV and optical deformation constant Pod = 4.0 × 10^17 eV/m. This means that electrons are scattered by the acoustic deformation phonons at low temperatures and optical deformation phonons at high temperatures, respectively. The magnetic field （B） dependence of the relaxation times is T1 ∝ B-2.7 at 100 K and T1 ∝ B-2.3 at 150 K, which nearly agree with the result of Yafet, T1 ∝ B-3.0- B -2.5.
文摘The influence of a Co or phthalocyanine (Pc) molecular overlayer on the properties of quantum-well resonances (QWR) in Cu layers atop Co(001) is studied by means of spin-polarized electron reflection. For Co atoms and Pc molecules, an energy shift of the QWR-induced signal is observed with increasing coverage and is attributed to a variation of the electron reflection phase at the Cu/Co and Cu/Pc interface. For Co we find a linear energy shift in the Cu QWR energy position with increasing coverage down to the sub-monolayer regime. This shows that the phase accumulation model remains accurate within the sub-monolayer regime of a discontinuous interface. An opposite sign in the energy shift between Co and Pc overlayers could reflect an opposite impact on the Cu surface work function of overlayer adsorption.
