共查询到20条相似文献,搜索用时 625 毫秒
1.
A. I. Ismailova O. I. Gnezdilov A. A. Obynochny L. N. Muranova V. V. Andrianov Kh. L. Gainutdinov A. G. Nasyrova R. R. Nigmatullina F. F. Rakhmatullina A. L. Zefirov 《Applied magnetic resonance》2005,28(3-4):421-430
Electron spin resonance (ESR) of the ternary (DETC)2-Fe2+-NO complex has been applied to determine the nitric oxide production in tissues of rats and snails. A preliminary ESR study of the NO content in tissues of rats before and after artificially induced acute myocardial infarct was performed. The analysis of the obtained results shows that the nitric oxide production during the first hour after the moment of inducing myocardial infarct decreases. It is also demonstrated that ESR may be useful in the study of the influence of the long-term sensitization of snails on the nitric oxide production in their body. The changes in the NO production after the external influences in both cases are discussed. 相似文献
2.
J. Ren P. C. W. Fung C. Chang G. X. Shen G. Lu F. H. Y. Chan K. J. Liu J. Shen 《Applied magnetic resonance》2007,32(3):243-255
Electron paramagnetic resonance (EPR) spin trapping technology is a sensitive and unambiguous method for detection of nitric
oxide (NO). Due to the short lifetime, NO must be trapped before EPR measurement. There are two EPR spin trapping techniques
used currently, including the detections of EPR signals of diethyldithiocarbamate-iron-nitric oxide (DETC2-Fe2+-NO) and nitrosyl hemoglobin (HbNO). In this study, we firstly investigated the kinetics of the EPR signal of DETC2-Fe2+-NO in normal and ischemia-reperfused kidneys. In normal rat kidneys, the signal of DETC2-Fe2+-NO was found at 5 min after the spin trappers Fe2+/DETC were administrated, the peak concentration was at 15 min and the period with relatively stable signal intensity was
at the time range from 15 to 70 min. In the ischemia-reperfused rat kidneys, the signal of DETC2-Fe2+-NO was increased at 30 min of ischemia and decreased at 60 min of ischemia after the occlusion of renal artery (corresponding
to the time course of 60 and 90 min after Fe2+/DETC injection respectively). We then investigated the EPR signal of HbNO in blood. No characteristic HbNO signal was found
in the rats of the sham control and 30 min of ischemia. An HbNO signal occurred in the rats exposed to 60 min of ischemia
and it became pronounced with increased duration of reperfusion. The signal intensity reached a plateau at 150 min of reperfusion.
The results suggest that the DETC2-Fe2+-NO signal can be only suitable for the NO measurement in the short-term ischemia-reperfusion model, whereas the HbNO signal
can be applied to represent NO in the relatively long-term ischemia-reperfusion model. In addition, NG-nitro-L-arginine (L-NAME) and allopurinol were used to identify the source of NO. By detecting the HbNO signal, we demonstrated
that the activation of xanthine oxidase is an important source of NO formation at the long-term period of ischemia and reperfusion.
Authors' address: Jiangang Shen, School of Chinese Medicine, University of Hong Kong, 10 Sassoon Road, Hong Kong SAR, China 相似文献
3.
With sodium nitrite NaNO2 as a standard source of nitric oxide, we compared the correlation coefficients obtained by three measuring methods used currently in the determination of the NOFe2+ (DETC)2 complex (DETC, N,N-diethyldithiocarbamate) with that of the measuring method suggested in this study. The result showed that measuring the total height of triplet signals was the best linear correlation to the concentration of NO compared with other methods used in this system. With this method, we observed the effect of chinonin on the NOFe2+ (DETC)2 complex in myocardial ischemic-reperfusion injury in vivo. The hearts of Wistar rats were subjected to 30 min of ischemia and 10 min of reperfusion in vivo. Different doses of chinonin (5, 10, 25, 50 mg/kg intraperitoneally) were administered to the ischemic-reperfusion rats. Chinonin increased the signal intensity of the NOFe2+ (DETC)2 complex, inhibited the formation of thiobarbituric acid reaction substance and release of creatine kinase, and mitigated the incidence of ventricular arrhythmia in a dose-dependent way. Chinonin has cardiovascular protective effects by means of adjusting the level of NO and inhibiting oxygen free-radical-induced lipid peroxidation in myocardial ischemic-reperfusion injury in vivo. 相似文献
4.
一氧化氮自由基具有重要的生物功能.但目前使用的自旋捕捉剂都不能有效捕捉细胞和组织体系产生的一氧化氮自由基.实验表明DETC(mononitrosyl dithiocarbamate)铁络合物可以有效捕捉生物体系产生的一氧化氮自由基,但用DETC在细胞和组织体系检测一氧化氮自由基需要在低温检测.生物组织在低温的ESR波谱和DETC铁络合物捕捉的一氧化氮自由基的ESR波谱互相重叠,使谱线解析有一定困难.本文分析了用DETC铁络合物检测细胞和组织体系产生一氧化氮自由基在低温可能出现的ESR信号的g值和超精细分裂常数.提出了克服使用DETC铁络合物检测生物体系一氧化氮自由基困难的方法. 相似文献
5.
The reaction of nitric oxide with ZSM-5 zeolite ion-exchanged by Co(II) (Co-ZSM-5) has been studied by electron spin resonance (ESR), Fourier transform infrared (FTIR) and diffuse reflectance ultraviolet-visible spectroscopy. When dehydrated Co-ZSM-5 reacts at room temperature with nitric oxide, the ESR spectrum of Co(II) atg = 5.5, which is only observable below 45 K, is greatly reduced and a new59Co hyperfine octet forms at gavg = 2.11. The overall Co(II) ESR intensity decreases by about 50% which suggests formation of some diamagnetic cobalt complex. Mononitrosyl cobalt complexes such as Co(I)-NO+ or less probably Co(III)-(NO)− are suggested as possible precursors of a dintrosyl cobalt complex. The octet indicates hyperfine interaction with59Co and is associated with a cobalt dinitrosyl complex. FTIR bands at 1813 and 1896 cm−1 confirm a dinitrosyl species and a broad band from 1600–1800 cm−1 is tentatively interpreted as a mononitrosyl species. The visible spectrum for dehydrated Co-ZSM-5 shows a tetrahedral Co(II) band from 500–700 nm with three components which disappears after NO adsorption at room temperature. We suggest that Co(0)-(NO)22+ forms after NO adsorption onto Co(II)-ZSM-5 zeolite on the basis of ESR and ultraviolet-visible spectroscopy. 相似文献
6.
7.
Qiang Wang Yali Chen Jun Tang Zhangfang Zhang 《Journal of Macromolecular Science: Physics》2013,52(10):1405-1413
The thermodynamic parameters of epoxidized soybean oil (ESO) were determined by means of inverse gas chromatography (IGC) in the temperature range of 303.15 K-343.15 K. Two groups of probe solvents with different chemical natures and polarities were used to obtain information about ESO. The thermodynamic parameters—such as molar heat of sorption, weight fraction activity coefficient, Flory–Huggins interaction parameter, and partial molar heat of mixing—were obtained to judge the interactions between ESO and solvents at the studied temperatures. Also, the solubility parameters of ESO were found by plotting the graph of δ1 2/(RT) – χ∞ 12/V1 vs. solubility parameters, δ1, of the probes. The results showed that the selected solvent ethyl acetate was a moderate solvent for ESO; n-hexane was a moderate (but close to a better) solvent; while the probes n-heptane, n-octane, n-nonane, and chloroform were excellent solvents. From the extrapolation to 298 K, the solubility parameter value of ESO was 16.70 (J/cm3)0.5. 相似文献
8.
M. I. Ibragimova V. Yu. Petukhov E. P. Zheglov G. V. Konjukhov R. N. Nizamov 《Applied magnetic resonance》2005,29(4):589-596
The metabolic changes in probes of blood and tissue (spleen, liver and kidney) of mice under total γ-irradiation with the
doses varied in the interval of 1–10 Gy at the dose rate of 0.073 Gy/min were studied in the early postirradiation period
by ex vivo electron paramagnetic resonance (EPR). It was established that the impact with the lower dose rate leads to more
intensive nitric monoxide biosynthesis in comparison with higher dose rates. In the early postirradiation period (from 2 up
to 6 h), irradiation with doses higher than 2 Gy brings about an increase of the NO concentration and, hence, the appearance
of nitrosyl complexes which were registered directly by EPR in blood and spleen. The observed line is identified as the signal
from α-(Fe2+-NO)2β(Fe3+)2 or α-(Fe2+-NO) α(Fe2+)β(Fe3+)2 complexes since the methemoglobin concentration also increases in comparison with the control level. The concentration of
Hb-NO complexes in blood and spleen depends on the dose and individual radiosensitivity of the organism. Therefore, the intensity
of the Hb-NO signal may serve as a criterion of the radiation injury level during the first hours after the irradiation. 30
h after the impact, the Hb-NO complexes were no longer detected. For the first day, the concentration of Fe3+-transferrin in blood increases with the dose and time passed after the irradiation. The intensity of the EPR signal from
Fe3+-transferrin in blood may also serve as a measure of the radiation injury level. 相似文献
9.
H. Engelmann F. Mouahid I. Dézsi B. Molnár U. Gonser D. Siebert J. Dahlem F. Tuczek 《Applied Physics A: Materials Science & Processing》1989,48(3):211-217
Samples of the system LiNbO3-Fe2O3 prepared by water quenching and by the double-roller quenching method in the range up to 24 mol% Fe2O3 were investigated by Mössbauer and ESR spectroscopy. In the water quenched samples up to 11 mol% Fe2O3 only the Fe3+ and the Fe2+ valence states could be detected. The Fe2+ concentration decreased with increasing Fe2O3 content. Above 11 mol% Fe2O3 magnetically split Mössbauer spectra indicated the presence of Fe2O3 clusters. The isomer shift values of Fe3+ as a function of Fe2O3 concentration showed jumps at 6 and 11 mol% Fe2O3, whereas no significant changes could be detected in the quadrupole splitting values. The ESR data already exhibited the existence of isolated Fe3+ ions and of clusters with Fe-Fe distances less than 8 Å for the lowest Fe2O3 concentration. The cluster signal intensity increased with increasing Fe2O3 content. The roller quenched samples showed increased Fe2+ concentration as compared to the water quenched samples, which suggests that slow quenching results in iron oxidation and cluster formation. For low Fe2O3 concentrations a valence state change Fe3+Fe2+ can easily be obtained by heat treatments in various atmospheres, whereas for higher Fe2O3 contents (9.8 mol%) precipitations of-Fe (in reducing atmosphere) and Fe2O3 (in air) could be observed in addition to the valence state changes of a remaining part of dissolved Fe ions. On the basis of the obtained results a model was suggested for the unusual behaviour of the lattice parameters observed in LiNbO3-Fe2O3. 相似文献
10.
Nandhibatla V. Sastry Rakesh R. Thakor Mitesh C. Patel 《Journal of Molecular Liquids》2009,144(1-2):13-22
The experimental densities (ρ), dynamic viscosities (η), speeds of sound (υ) and relative permittivities (εr) of thirty six binary mixtures of esters (methyl acetate, ethyl acetate, butyl acetate and isoamyl acetate) + organic solvents (n-hexane, benzene, toluene, o-, m-, p- xylenes), + halogenated benzene (chloro-, bromobenzene), + nitrobenzene have been measured over the complete composition range at atmospheric pressure and temperatures (298.15 to 313.15 K). The excess molar volumes, VmE, excess isentropic compressibilities, κsE, deviations in relative permittivities, δεr have been calculated and fitted to Redlisch–Kister type equation. The dynamic and kinematic viscosities have been correlated through Grunberg–Nissan and MacAllister equations. The qualitative analysis of various functions revealed that i.) esters lose their dipolar association in presence of inert and unlike n-hexane, ii.) specific but weaker n…π type interactions predominate in binary mixtures of esters + aromatic organic solvents and iii.) weak electron donor–acceptor complexes predominate in the mixtures of esters with halogenated and nitrated benzene. 相似文献
11.
Toshihide Tsuji Yoshikazu Mochida Keiji Naito Koji Shibuya 《Hyperfine Interactions》1992,68(1-4):287-290
The effects of calcium and zinc on the room-temperature coercivity of γ-Fe2O3 particles having cobalt ions adsorbed in 3M NaOH solution at 373K have been studied. When the Ca2+ ions are adsorbed on the γ-Fe2O3 prior to Co2+ ions adsorption, the coercivity of Co-modified γ-Fe2O3 significantly increases compared with that of γ-Fe2O3 modified only with Co2+ ions. In the case of Zn2+ ions, the coercivity of Co-modified γ-Fe2O3 is the same as that of γ-Fe2O3 modified only with Co2+ ions. The emission Mössbauer spectrum of57Co2+ adsorbed on the surfaces of γ-Fe2O3 after pretreating with Ca2+ ions consists of a typical sextet of Fe3+ ions with hyperfine magnetic field, whereas those of γ-Fe2O3 modified only with Co2+ ions and with both Zn2+ and Co2+ ions show nonmagnetic components in addition to magnetic one. The effects of Ca2+ and Zn2+ ions on the adsorption of cobalt on the surface of γ-Fe2O3 are discussed from the viewpoint of site preference energy of cations in ferrite and distribution ratio of each cation. 相似文献
12.
V. ?epel��k M. J. Nasr Isfahani M. Myndyk M. Ghafari A. Feldhoff K. D. Becker 《Hyperfine Interactions》2011,202(1-3):39-46
A non-thermal route to oxide nanocomposites by mechanochemical redox reactions in the ??-Fe2O3 + SnO system is presented. The important impact of the work, from the methodology point of view, is the combined application of 57Fe and 119Sn Mössbauer spectroscopies to the study of the mechanically induced redox processes, resulting in the reduction of ??-Fe2O3 and the oxidation of SnO. In addition, the obtained product was characterized by X-ray diffraction and transmission electron microscopy. 相似文献
13.
The 57Fe Mössbauer spectra recorded in situ from tin-doped Fe3O4 at elevated temperature in vacuo shows the Curie temperature to decrease with increasing concentrations of the dopant. Thermal treatment under oxidising conditions results in the initial formation of tin-doped γ-Fe2O3 which subsequently undergoes a phase transformation to tin-doped α-Fe2O3. 57Fe Mössbauer spectroscopy at elevated temperatures shows the Néel temperature for tin-doped γ-Fe2O3 to be lower than that of pure γ-Fe2O3. The 119Sn Mössbauer spectra recorded from all the tin-doped iron oxides show the presence of a hyperfine magnetic field at the Sn4+ site which is more complex in the spectra recorded from tin-doped γ-Fe2O3 and α-Fe2O3. 相似文献
14.
Wenshu Tang Qi Li Caifu Li Shian Gao Jian Ku Shang 《Journal of nanoparticle research》2011,13(6):2641-2651
Without the addition of surfactants or templates, ultrafine α-Fe2O3 nanoparticles were successfully synthesized by a solvent thermal process at low temperature. During the synthesis, in situ
self-formed “cage” of crystallized NaCl confined the growth of α-Fe2O3 nanoparticles in both the precipitation and solvent thermal processes, resulting in the creation of well-crystallized α-Fe2O3 nanoparticles with an average particle size about 4–5 nm and a high-specific surface area of ~162 m2/g. High resolution TEM investigations provided clear evidences of the in situ self-formation of NaCl “cage” during the synthesis
and its confinement effect on the growth of α-Fe2O3 nanoparticles. The superior performance of these α-Fe2O3 nanoparticles on the adsorption of arsenite(III) (As) from aqueous environment was demonstrated with both lab-prepared and
natural water samples at near neutral pH environment when compared with previously reported removal effects of As(III) by
Fe2O3. This unique approach may also be utilized in the synthesis of other ultrafine metal oxide nanoparticles for a broad range
of technical applications. 相似文献
15.
Imperviousness of the hydrophobic silica aerogels against various solvents and acids 总被引:1,自引:0,他引:1
A. Venkateswara Rao Nagaraja D. Hegde Poonam M. Shewale 《Applied Surface Science》2007,253(9):4137-4141
The experimental results on the imperviousness of the silica aerogels against various organic solvents and acids, are reported. Various types of hydrophobic silica aerogels were prepared using methyltrimethoxysilane (MTMS); tetraethoxysilane (TEOS) with ethyltriethoxysilane (ETES) and phenyltriethoxysilane (PTES) as co-precursors. The organic solvents used were: methanol, ethanol and acetone, and the acids used were: hydrochloric acid (HCl), nitric acid (HNO3) and sulphuric acid (H2SO4). The imperviousness of the aerogels against these solvents and acids were tested with the variation of the percentage of organic solvents and acids in water from 10 to 100% and was characterized by the contact angle measurements. It was observed that in all the cases, the contact angle decreased with an increase in the percentage of solvent in water. While there was no absorption of the solvent up to 20% in water by the ETES and PTES modified aerogels, the MTMS-based aerogels showed the imperviousness up to 60% of the solvent in water. The MTMS aerogels were also impervious against all the three acids up to 100%, while the ETES and PTES modified aerogels could withstand only up to 80% of acids in water. 相似文献
16.
Satyawati S. Joshi Prajakta R. Patil Madhav S. Nimase P.P. Bakare 《Journal of nanoparticle research》2006,8(5):635-643
The electrochemical synthesis of alpha Fe2O3 nanoparticles was performed using quaternary ammonium salts viz. TPAB, TBAB and TOAB in an organic medium by optimizing current density and molar concentration of the ligand. The role of ligands in the formation of α phase, structure and magnetic properties was investigated in details. The effect of increasing chain length on the particle size confirmed that as the chain length increases from propyl to octyl, the particle size decreases. X-ray diffraction spectra of as prepared samples and TEM analysis confirmed the amorphous nature of iron oxide. TEM showed beads of iron oxide joined together with a size distribution in the range of 6–30 nm. The Mossbauer studies also support this observation that for the lowest particle size, the line width is broader which successively reduces with increase in particle size. Iron oxide capped with TOAB indicated superparamagnetic nature at room temperature. The resultant internal magnetic field of 506 mm/s due to hyperfine splitting clearly established the formation of α-Fe2O3 The infrared spectroscopy and pH measurements revealed the binding of tetra alkyl ligand with iron oxide. The IR spectra and the increase in basicity of as prepared samples confirmed the formation of hydrated iron oxide. Above 800°C the spectra indicated only iron oxide. Surface area obtained by BET method was 205 m2/g. 相似文献
17.
Kh. L. Gainutdinov S. A. Gavrilova V. S. Iyudin A. V. Golubeva M. P. Davydova G. G. Jafarova V. V. Andrianov V. B. Koshelev 《Applied magnetic resonance》2011,40(3):267-278
Electron paramagnetic resonance of (DETC)2–Fe2+–NO complexes has been used as a method to detect the formation of nitric oxide (NO) in the brain tissues of Wistar rats.
The content of nitric oxide in the center of ischemia (left brain hemisphere), in the non-ischemic part of the left hemisphere,
and also in the regions conditionally not affected by ischemia, the cerebral cortex of the right hemisphere and the cerebellum
of rats was studied in 5, 9, 24 and 72 h after modeling an ischemic stroke. It is found that in the ischemic part of the left
hemisphere in 5 h after modeling the ischemic stroke, the NO content in the spin trap and R-conformer compositions decreases
by 5 times and 30%, respectively. This decrease in the NO content is found in 9 and 24 h after the stroke. In the cerebral
cortex of the right hemisphere and non-ischemic parts of the cerebral cortex of the left hemisphere, the NO content in the
composition of the spin trap in 5, 9 and 24 h after the stroke decreases by 40–50%. In the composition of the R-conformer
it does not vary. In 72 h, the partial restoration of the NO content in all regions except for the ischemia zone is observed. 相似文献
18.
19.
Monica Sorescu L Diamandescu D Tarabasanu-Mihaila 《Journal of Physics and Chemistry of Solids》2004,65(10):1719-1725
α-Fe2O3-In2O3 mixed oxide nanoparticles system has been synthesized by hydrothermal supercritical and postannealing route, starting with (1−x)Fe(NO3)3·9H2O·xIn(NO3)3·5H2O aqueous solution (x=0-1). X-ray diffraction and Mössbauer spectroscopy have been used to study the phase structure and substitutions in the nanosized samples. The concentration regions for the existence of the solid solutions in the α-Fe2O3-In2O3 nanoparticle system together with the solubility limits of In3+ ions in the hematite lattice and of Fe3+ ions in the cubic In2O3 structure have been evidenced. In general, the substitution level is considerably lower than the nominal concentration x. A justification of the processes leading to the formation of iron and indium phases in the investigated supercritical hydrothermal system has been given. 相似文献
20.
The question whether chemical reactions and diffusion processes in ionic liquids are comparable with those taking place in classical organic liquids is a current issue in the literature. Pressure- and temperature-dependent investigations on simple electron self-exchange reactions between the two partners of a redox couple are good tools to get a better understanding of how the solvent influences such reactions. The electron self-exchange reaction between tetrathiafulvalene (TTF) and its radical cation has been investigated in two ionic liquids and two organic solvents using electron spin resonance (ESR) line broadening experiments at variable temperature and pressure. Rate constants are reported for the ionic liquids 1-ethyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim+][Tf2N?]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim+][Tf2N?]) within a temperature range of 298 K ≤ T ≤ 368 K and a pressure range of 0.1 MPa ≤ p ≤ 100 MPa. The self-exchange reaction of the redox couple [TTF/TTF?+] has been found to be diffusion-controlled in the used ionic liquids over the entire temperature range. The observed rate constants in ionic liquids at higher pressures are larger than those predicted by common diffusion, and suggest that the electron transfer takes place within a solvent cage. Also, the self-exchange reaction of the [TTF/TTF?+] redox couple in classical solvents (dimethylphthalate (DMP) and acetonitrile) was investigated and compared to the results with those obtained in ionic liquids. The high viscosity of the ionic liquids makes it difficult to extract the electron transfer rate constants reliably, making interpretation within the framework of the Marcus Theory impossible. 相似文献