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
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
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
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
Gold nanostructures are among the noble metal nanomaterials being intensely studied due to their good biocompatibility, tunable localized surface plasmon resonance (SPR), and ease of modification. These properties g...Gold nanostructures are among the noble metal nanomaterials being intensely studied due to their good biocompatibility, tunable localized surface plasmon resonance (SPR), and ease of modification. These properties give gold nano- structures many potential chemical and biomedical applications. Herein, we demonstrate the critical role of oxygen activation during the decomposition of hydrogen peroxide (H202) in the presence of photoexcited gold nanorods (AuNRs) by using electron spin resonance (ESR) techniques. Upon SPR excitation, 02 is activated first, and the resulting reactive intermediates further activate H202 to produce ,OH. The reactive intermediates exhibit singlet oxygen-like (102-1ike) reactivity, indicated by 102-specific oxidation reaction, quenching behaviors, and the lack of the typical 102 ESR signal. In addition, by using the antioxidant sodium ascorbate (NaA) as an example, we show that hydroxyl radicals from H202 activation can induce much stronger NaA oxidation than that in the absence of H202. These results may have significant biomedical implications. For example, as oxidative stress levels are known to influence tumorigenesis and cancer progression, the ability to control redox status inside tumor microenvironments using noble metal nanostructures may provide new strategies for regulating the metabolism of reactive oxygen species and new approaches for cancer treatment.展开更多
<Abstract>In order to explore the production of hydroxyl radical(·OH)in a confined space,a novel ozone-light irradiation system is constructed in this study,and the·OH radical is measured by spin-trapp...<Abstract>In order to explore the production of hydroxyl radical(·OH)in a confined space,a novel ozone-light irradiation system is constructed in this study,and the·OH radical is measured by spin-trapping electron spin resonance(ESR)method in which 5,5-dimethyl-1-pyrroline-N-oxide(DMPO)is selected as the spin-trap.Several influence factors including the light intensity,the irradiation time and DMPO mass concentration are discussed. The results show that in this experimental system,with DMPO mass concentration of 1g/L and the irradiation time of 30 min,the·OH radical can be best captured.Besides,both wavelength and intensity of the irradiation light could effect the generation of·OH radical.These results are of great importance to further study the sterilization effect of·OH radical in confined space.展开更多
The rate of oxygen consumption and the yield of free radical anion of hematoporphyrin derivative (HPD) in aqueous solutions of HPD and pyrocatechol were measured by the probe 2,2,6,6-tetramethyl4-piperidone-1-oxyl.It ...The rate of oxygen consumption and the yield of free radical anion of hematoporphyrin derivative (HPD) in aqueous solutions of HPD and pyrocatechol were measured by the probe 2,2,6,6-tetramethyl4-piperidone-1-oxyl.It has been found that both singlet oxygen and free radical mechanisms exist simultaneously in primary photochemical reactions, and there is a competition between both mechanisms. When the oxygen concentration in solutions comes down to 12-14% of the stanting level, the predominant mechanism can be changed from the singlet oxygen to the free radical.Whether HPD exists in aggregation state is very important to photosensitization mechanisms.In the presence of the aggregation state of HPD, the predominant mechanism is the free radical,and photosensitization effects of HPD are all the better.展开更多
CH_3CCo_3(CO)_9 was synthesized from the reaction between chloralose and Co_2(CO)_. The radical anion was generated by electrochemical reduction,and electron spin resonance spectra in THF were recorded by in situ elec...CH_3CCo_3(CO)_9 was synthesized from the reaction between chloralose and Co_2(CO)_. The radical anion was generated by electrochemical reduction,and electron spin resonance spectra in THF were recorded by in situ electrolysis in the sample tube in the ESR cavity at 298 and 110K with the spectral data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
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
After bilateral carotid artery occlusion for 30 minutes and reperfusion for 2 hours, distinct pathological changes presented in the cerebral cortex and cerebellum of rats. Compared with normal rats, nerve cell membran...After bilateral carotid artery occlusion for 30 minutes and reperfusion for 2 hours, distinct pathological changes presented in the cerebral cortex and cerebellum of rats. Compared with normal rats, nerve cell membrane fluidity significantly decreased in ischemia/reperfusion rats as detected by spin-labeling electron spin resonance, consistent with order parameter S and rotational correlation time TC measurements. Brain nerve cells from rats with ischemia/reperfusion injury were cultured with 1-100 mg/mL Buyang Huanwu decoction. Results showed that Buyang Huanwu decoction gradually increased membrane fluidity dose-dependently to normal levels, and eliminated hydroxide (OH') and superoxide (O2') free radicals dose-dependenUy. These findings suggest that Buyang Huanwu decoction can protect against cell membrane fluidity changes in rats with ischemia/ reperfusion injury by scavenging free radicals.展开更多
A polycrystalline sample Ndo.5Sro.3Cao.2MnO3 is prepared by the conventional solid state reaction method. The structure and magnetic properties are investigated with x-ray diffraction (XRD) patterns, a superconducti...A polycrystalline sample Ndo.5Sro.3Cao.2MnO3 is prepared by the conventional solid state reaction method. The structure and magnetic properties are investigated with x-ray diffraction (XRD) patterns, a superconducting quantum in- terference device (SQUID), and electron spin resonance (ESR). The sample is in single phase with the space group Pbnm symmetry. With the decrease of temperature, Ndo.sSro.3Cao.2MnO3 undergoes three magnetic transitions: ferromagnetic transition at Tc ≈ 210 K, charge-ordering at Tco ≈ 175 K, and antiferromagnetic transition at TN = 155 K. In addition, the activation energy Ea ≈ 52.78 meV can be extracted by curve fitting.展开更多
Objective To study the oxidative stress induced by consumption of mercury-contaminated rice in rats, and to assess the possible public health risk of mercury contamination in Wanshan mining area. Methods Sprague Dawle...Objective To study the oxidative stress induced by consumption of mercury-contaminated rice in rats, and to assess the possible public health risk of mercury contamination in Wanshan mining area. Methods Sprague Dawley rats were fed the mercury-contaminated rice produced from Wanshan area for 90 days. The antioxidant status and the free radicals in rat serum were evaluated. Results High mercury accumulation in organs of rats fed the mercury-contaminated rice confirmed the server pollution of mercury in Wanshan mining area. The intensity of electron spin resonance (ESR) signal increased by 87.38% in rats fed the rice from Wanshan compared with that in the control rats fed the rice from Shanghai, suggesting that chronic dietary consumption of rice from mercury mining area could induce an aggravation of free radicals. Feeding the mercury-contaminated rice was associated with significant decreases in the antioxidant enzymatic activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and concentration of serum nitric oxide (NO), but it had no effect on serum nitric oxide synthase (NOS) activity. Feeding the mercury-contaminated rice raised the level of serum malonyldialdehyde (MDA), indicating the occurrence of oxidative stress. Conclusion The long-term dietary consumption of mercury-contaminated rice induces the aggravation of free radicals and exerts oxidative stress.展开更多
With annealing temperature kept at 1573 K, the effects of annealing time on stability of the intrinsic defects in epitaxial unintentionally doped 4H-SiC prepared by low pressure chemical vapour deposition have been st...With annealing temperature kept at 1573 K, the effects of annealing time on stability of the intrinsic defects in epitaxial unintentionally doped 4H-SiC prepared by low pressure chemical vapour deposition have been studied by electron spin resonance (ESR) and low temperature photoluminescence. This paper reports the results shown that annealing time has an important effect on the intrinsic defects in unintentionally doped 4H-SiC when annealing temperature kept at 1573 K. When the annealing time is less than 30 min, the intensity of ESR and photoluminescence is increasing with annealing time prolonged, and reaches the maximum when annealing time is 30 min. Then the intensity of ESR and photoluminescence is rapidly decreased with the longer annealing time, and much less than that of as-grown 4H-SiC when annealing time is 60 min, which should be related with the interaction among the intrinsic defects during the annealing process.展开更多
The ferromagnetic semiconductor La2NiMnO6 (LNMO) has recently received much attention due to its high Curie temperature (Tc 280 K), which is close to room temperature. We prepared single-phase LNMO polycrystaUine...The ferromagnetic semiconductor La2NiMnO6 (LNMO) has recently received much attention due to its high Curie temperature (Tc 280 K), which is close to room temperature. We prepared single-phase LNMO polycrystaUine samples and investigated the temperature- and field-dependent magnetic behaviors of bulk LNMO. Between Tc and T* = 300 K, we observed upward and downward deviations from the Curie-Weiss law for high and low magnetic fields, respectively. From the electron spin resonance results, we can exclude the existence of the Griffiths phase. On the contrary, our results indicate that the abnormal magnetic behaviors might be induced by antisite phase boundaries with antiferromagnetic interaction.展开更多
Many oils from plants are important components of our food chain and maintaining their oxidative stability (OS) is economically and nutritionally important. OS is dependent in part on antioxidant capacity (AC) arising...Many oils from plants are important components of our food chain and maintaining their oxidative stability (OS) is economically and nutritionally important. OS is dependent in part on antioxidant capacity (AC) arising from the electron donating ability of endogenous compounds in the oils. Attention has focused on the contribution to AC of phenolic compounds in oils as many have bioactivities in vitro. However, the relevance of such phenolics to healthy nutrition remains unclear. In contrast, many plant-derived oils also contain tocopherol homologs, which as vitamin E are dietary-essential, lipid-soluble antioxidants. We have determined the AC of twelve “off the shelf” edible oils by assessing their ability to quench galvinoxyl, a stable free radical species. The stochiometric reactivity of vitamin E with galvinoxyl indicates that the combined dα-tocopherol and dγ-tocopherol homologs contribute between 20% (olive) and 85% (soya) to AC depending on type of oil. Tocopherols are important contributors to the AC of several vegetable oils. Breeding and photo mixotrophic programmes to enhance content in edible oil crops of this important vitamin may have a positive impact not only on oil stability during storage but also in contributing to provision of optimum dietary intakes for health.展开更多
The commercial TiO2 nanopowder and micropowder of anatase phase and rutile phase have been characterized by X-ray diffraction (XRD) and electron spin resonance (ESR) spectroscopy. XRD patterns and ESR spectra of n...The commercial TiO2 nanopowder and micropowder of anatase phase and rutile phase have been characterized by X-ray diffraction (XRD) and electron spin resonance (ESR) spectroscopy. XRD patterns and ESR spectra of nano-TiO2 in rutile and anatase phases exhibit broad peaks whereas both phases of micro-TiOz demonstrate very sharp peaks. Furthermore, the anatase phase of both particle sizes provide ESR peak at a magnetic field around 3568.25G, On the other hand, this peak is not established in the rutile phase of both particle sizes.展开更多
Background:Antioxidants and the duration of treatment after noise exposure on hearing recovery are important.We investigated the protective effects of an antioxidant substance,edaravone,and its slow-release dosage fo...Background:Antioxidants and the duration of treatment after noise exposure on hearing recovery are important.We investigated the protective effects of an antioxidant substance,edaravone,and its slow-release dosage form,edaravone solid lipid nanoparticles (SLNs),in steady noise-exposed guinea pigs.Methods:SLNs loaded with edaravone were produced by an ultrasound technique.Edaravone solution or edaravone SLNs were administered by intratympanic or intravenous injection after the 1st day of noise exposure.Guinea pigs were exposed to 110 dB sound pressure level (SPL) noise,centered at 0.25-4.0 kHz,for 4 days at 2 h/d.After noise exposure,the guinea pigs underwent auditory brainstem response (ABR) threshold measurements,reactive oxygen species (ROS) were detected in their cochleas with electron spin resonance (ESR),and outer hair cells (OHCs) were counted with silvernitrate (AgNO3) staining at 1,4,and 6 days.Results:The ultrasound technique was able to prepare adequate edaravone SLNs with a mean particle size of 93.6 nm and entrapment efficiency of 76.7%.Acoustic stress-induced ROS formation and edaravone exerted a protective effect on the cochlea.Comparisons of hearing thresholds and ROS changes in different animal groups showed that the threshold shift and ROS generation were significantly lower in treated animals than in those without treatment,especially in the edaravone SLN intratympanic injection group.Conclusions:Edaravone SLNs show noticeable slow-release effects and have certain protective effects against noise-induced hearing loss (NIHL).展开更多
The electrolysis of catechol was studied in the pH values of 1 to 10. The results from the rotating ring disk electrode (RRDE) experiments show that at low pH values, the electrochemical polymerization of catechol wa...The electrolysis of catechol was studied in the pH values of 1 to 10. The results from the rotating ring disk electrode (RRDE) experiments show that at low pH values, the electrochemical polymerization of catechol was performed by one step, and at higher pH values, the electrochemical polymerization of catechol was carried out by two steps, i.e . oxidation of catechol and followed by polymerization. The intermediates generated at the disk were detected at the ring electrode in the ring potential region of -0.2 to 0 V (vs. Ag/AgCl). One of reasons for the decrease in the ratio of i r to i d with increasing the ring potential is caused by formation of positively charged intermediates at the disk electrode. This ratio increases with increasing the rotation rate of the RRDE, which indicates that the intermediates are not stable. A shielding effect during polymerization of catechol was observed when the ring potential was set at 0.1 V (vs. Ag/AgCl). The electron spin resonance (ESR) of polycatechol shows that polycatechol possesses unpaired electrons. The images of polycatechol films synthesized at different conditions are described.展开更多
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.
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).
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 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Gold nanostructures are among the noble metal nanomaterials being intensely studied due to their good biocompatibility, tunable localized surface plasmon resonance (SPR), and ease of modification. These properties give gold nano- structures many potential chemical and biomedical applications. Herein, we demonstrate the critical role of oxygen activation during the decomposition of hydrogen peroxide (H202) in the presence of photoexcited gold nanorods (AuNRs) by using electron spin resonance (ESR) techniques. Upon SPR excitation, 02 is activated first, and the resulting reactive intermediates further activate H202 to produce ,OH. The reactive intermediates exhibit singlet oxygen-like (102-1ike) reactivity, indicated by 102-specific oxidation reaction, quenching behaviors, and the lack of the typical 102 ESR signal. In addition, by using the antioxidant sodium ascorbate (NaA) as an example, we show that hydroxyl radicals from H202 activation can induce much stronger NaA oxidation than that in the absence of H202. These results may have significant biomedical implications. For example, as oxidative stress levels are known to influence tumorigenesis and cancer progression, the ability to control redox status inside tumor microenvironments using noble metal nanostructures may provide new strategies for regulating the metabolism of reactive oxygen species and new approaches for cancer treatment.
文摘<Abstract>In order to explore the production of hydroxyl radical(·OH)in a confined space,a novel ozone-light irradiation system is constructed in this study,and the·OH radical is measured by spin-trapping electron spin resonance(ESR)method in which 5,5-dimethyl-1-pyrroline-N-oxide(DMPO)is selected as the spin-trap.Several influence factors including the light intensity,the irradiation time and DMPO mass concentration are discussed. The results show that in this experimental system,with DMPO mass concentration of 1g/L and the irradiation time of 30 min,the·OH radical can be best captured.Besides,both wavelength and intensity of the irradiation light could effect the generation of·OH radical.These results are of great importance to further study the sterilization effect of·OH radical in confined space.
文摘The rate of oxygen consumption and the yield of free radical anion of hematoporphyrin derivative (HPD) in aqueous solutions of HPD and pyrocatechol were measured by the probe 2,2,6,6-tetramethyl4-piperidone-1-oxyl.It has been found that both singlet oxygen and free radical mechanisms exist simultaneously in primary photochemical reactions, and there is a competition between both mechanisms. When the oxygen concentration in solutions comes down to 12-14% of the stanting level, the predominant mechanism can be changed from the singlet oxygen to the free radical.Whether HPD exists in aggregation state is very important to photosensitization mechanisms.In the presence of the aggregation state of HPD, the predominant mechanism is the free radical,and photosensitization effects of HPD are all the better.
文摘CH_3CCo_3(CO)_9 was synthesized from the reaction between chloralose and Co_2(CO)_. The radical anion was generated by electrochemical reduction,and electron spin resonance spectra in THF were recorded by in situ electrolysis in the sample tube in the ESR cavity at 298 and 110K with the spectral data
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.
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.
基金supported by the Doctor Foundation(2008) in Shanxi Datong University
文摘After bilateral carotid artery occlusion for 30 minutes and reperfusion for 2 hours, distinct pathological changes presented in the cerebral cortex and cerebellum of rats. Compared with normal rats, nerve cell membrane fluidity significantly decreased in ischemia/reperfusion rats as detected by spin-labeling electron spin resonance, consistent with order parameter S and rotational correlation time TC measurements. Brain nerve cells from rats with ischemia/reperfusion injury were cultured with 1-100 mg/mL Buyang Huanwu decoction. Results showed that Buyang Huanwu decoction gradually increased membrane fluidity dose-dependently to normal levels, and eliminated hydroxide (OH') and superoxide (O2') free radicals dose-dependenUy. These findings suggest that Buyang Huanwu decoction can protect against cell membrane fluidity changes in rats with ischemia/ reperfusion injury by scavenging free radicals.
基金supported by the National Natural Science Foundation of China(Grant Nos.11164019,51562032,and 61565013)the Inner Mongolia Natural Science Foundation,China(Grant Nos.2015MS0109,NJZZ11166,and NJZY12202)the Science and Technology in Baotou Production-Study-Research Cooperation Projects,China(Grant No.2014X1014-01)
文摘A polycrystalline sample Ndo.5Sro.3Cao.2MnO3 is prepared by the conventional solid state reaction method. The structure and magnetic properties are investigated with x-ray diffraction (XRD) patterns, a superconducting quantum in- terference device (SQUID), and electron spin resonance (ESR). The sample is in single phase with the space group Pbnm symmetry. With the decrease of temperature, Ndo.sSro.3Cao.2MnO3 undergoes three magnetic transitions: ferromagnetic transition at Tc ≈ 210 K, charge-ordering at Tco ≈ 175 K, and antiferromagnetic transition at TN = 155 K. In addition, the activation energy Ea ≈ 52.78 meV can be extracted by curve fitting.
基金This work was supported by National Natural Science Foundation of China (No. 20607014)
文摘Objective To study the oxidative stress induced by consumption of mercury-contaminated rice in rats, and to assess the possible public health risk of mercury contamination in Wanshan mining area. Methods Sprague Dawley rats were fed the mercury-contaminated rice produced from Wanshan area for 90 days. The antioxidant status and the free radicals in rat serum were evaluated. Results High mercury accumulation in organs of rats fed the mercury-contaminated rice confirmed the server pollution of mercury in Wanshan mining area. The intensity of electron spin resonance (ESR) signal increased by 87.38% in rats fed the rice from Wanshan compared with that in the control rats fed the rice from Shanghai, suggesting that chronic dietary consumption of rice from mercury mining area could induce an aggravation of free radicals. Feeding the mercury-contaminated rice was associated with significant decreases in the antioxidant enzymatic activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and concentration of serum nitric oxide (NO), but it had no effect on serum nitric oxide synthase (NOS) activity. Feeding the mercury-contaminated rice raised the level of serum malonyldialdehyde (MDA), indicating the occurrence of oxidative stress. Conclusion The long-term dietary consumption of mercury-contaminated rice induces the aggravation of free radicals and exerts oxidative stress.
基金supported by the National Natural Science Foundation of China (Grant No.60876061)Pre-Research Foundation (Grant No.9140A08050508)the 13115 Innovation Engineering of Shanxi,China (Grant No.2008ZDKG-30)
文摘With annealing temperature kept at 1573 K, the effects of annealing time on stability of the intrinsic defects in epitaxial unintentionally doped 4H-SiC prepared by low pressure chemical vapour deposition have been studied by electron spin resonance (ESR) and low temperature photoluminescence. This paper reports the results shown that annealing time has an important effect on the intrinsic defects in unintentionally doped 4H-SiC when annealing temperature kept at 1573 K. When the annealing time is less than 30 min, the intensity of ESR and photoluminescence is increasing with annealing time prolonged, and reaches the maximum when annealing time is 30 min. Then the intensity of ESR and photoluminescence is rapidly decreased with the longer annealing time, and much less than that of as-grown 4H-SiC when annealing time is 60 min, which should be related with the interaction among the intrinsic defects during the annealing process.
基金supported by the National Key Basic Research Program of China(Grant No.2011CB921801)the National Natural Science Foundation of China(Grant Nos.11074293 and 51021061)
文摘The ferromagnetic semiconductor La2NiMnO6 (LNMO) has recently received much attention due to its high Curie temperature (Tc 280 K), which is close to room temperature. We prepared single-phase LNMO polycrystaUine samples and investigated the temperature- and field-dependent magnetic behaviors of bulk LNMO. Between Tc and T* = 300 K, we observed upward and downward deviations from the Curie-Weiss law for high and low magnetic fields, respectively. From the electron spin resonance results, we can exclude the existence of the Griffiths phase. On the contrary, our results indicate that the abnormal magnetic behaviors might be induced by antisite phase boundaries with antiferromagnetic interaction.
文摘Many oils from plants are important components of our food chain and maintaining their oxidative stability (OS) is economically and nutritionally important. OS is dependent in part on antioxidant capacity (AC) arising from the electron donating ability of endogenous compounds in the oils. Attention has focused on the contribution to AC of phenolic compounds in oils as many have bioactivities in vitro. However, the relevance of such phenolics to healthy nutrition remains unclear. In contrast, many plant-derived oils also contain tocopherol homologs, which as vitamin E are dietary-essential, lipid-soluble antioxidants. We have determined the AC of twelve “off the shelf” edible oils by assessing their ability to quench galvinoxyl, a stable free radical species. The stochiometric reactivity of vitamin E with galvinoxyl indicates that the combined dα-tocopherol and dγ-tocopherol homologs contribute between 20% (olive) and 85% (soya) to AC depending on type of oil. Tocopherols are important contributors to the AC of several vegetable oils. Breeding and photo mixotrophic programmes to enhance content in edible oil crops of this important vitamin may have a positive impact not only on oil stability during storage but also in contributing to provision of optimum dietary intakes for health.
基金supported by the Department of Physics,Faculty of Science,King Mongkut's University of Technology Thonburi
文摘The commercial TiO2 nanopowder and micropowder of anatase phase and rutile phase have been characterized by X-ray diffraction (XRD) and electron spin resonance (ESR) spectroscopy. XRD patterns and ESR spectra of nano-TiO2 in rutile and anatase phases exhibit broad peaks whereas both phases of micro-TiOz demonstrate very sharp peaks. Furthermore, the anatase phase of both particle sizes provide ESR peak at a magnetic field around 3568.25G, On the other hand, this peak is not established in the rutile phase of both particle sizes.
文摘Background:Antioxidants and the duration of treatment after noise exposure on hearing recovery are important.We investigated the protective effects of an antioxidant substance,edaravone,and its slow-release dosage form,edaravone solid lipid nanoparticles (SLNs),in steady noise-exposed guinea pigs.Methods:SLNs loaded with edaravone were produced by an ultrasound technique.Edaravone solution or edaravone SLNs were administered by intratympanic or intravenous injection after the 1st day of noise exposure.Guinea pigs were exposed to 110 dB sound pressure level (SPL) noise,centered at 0.25-4.0 kHz,for 4 days at 2 h/d.After noise exposure,the guinea pigs underwent auditory brainstem response (ABR) threshold measurements,reactive oxygen species (ROS) were detected in their cochleas with electron spin resonance (ESR),and outer hair cells (OHCs) were counted with silvernitrate (AgNO3) staining at 1,4,and 6 days.Results:The ultrasound technique was able to prepare adequate edaravone SLNs with a mean particle size of 93.6 nm and entrapment efficiency of 76.7%.Acoustic stress-induced ROS formation and edaravone exerted a protective effect on the cochlea.Comparisons of hearing thresholds and ROS changes in different animal groups showed that the threshold shift and ROS generation were significantly lower in treated animals than in those without treatment,especially in the edaravone SLN intratympanic injection group.Conclusions:Edaravone SLNs show noticeable slow-release effects and have certain protective effects against noise-induced hearing loss (NIHL).
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .2 0 0 740 2 7)
文摘The electrolysis of catechol was studied in the pH values of 1 to 10. The results from the rotating ring disk electrode (RRDE) experiments show that at low pH values, the electrochemical polymerization of catechol was performed by one step, and at higher pH values, the electrochemical polymerization of catechol was carried out by two steps, i.e . oxidation of catechol and followed by polymerization. The intermediates generated at the disk were detected at the ring electrode in the ring potential region of -0.2 to 0 V (vs. Ag/AgCl). One of reasons for the decrease in the ratio of i r to i d with increasing the ring potential is caused by formation of positively charged intermediates at the disk electrode. This ratio increases with increasing the rotation rate of the RRDE, which indicates that the intermediates are not stable. A shielding effect during polymerization of catechol was observed when the ring potential was set at 0.1 V (vs. Ag/AgCl). The electron spin resonance (ESR) of polycatechol shows that polycatechol possesses unpaired electrons. The images of polycatechol films synthesized at different conditions are described.