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41.
42.
The electrochemiluminescence (ECL) of luminol on indium tin oxide (ITO) glass was high even under a low potential around 0.4-0.5 V, which was quite different from other electrodes such as platinum. ITO nanoparticles were synthesized and used in the research on ITO glass in the ECL process. A static interaction between ITO and luminol is confirmed from UV-vis and fluorescence spectra. Then the ECL enhancement can be supposed to originate from the adsorption of luminol on ITO, which facilitated luminol’s oxidization to the excited state, giving out ECL. On the other hand, ITO can catalyze the generation of reactive oxygen species (ROSs), similar to some other nanomaterials, which also favored the ECL enhancement of luminol. 相似文献
43.
WST-1 and nitroblue tetrazolium (NBT) were used to quantify production of superoxide ions by leukocytes of the American alligator in whole blood. Because of the difficulty of isolating healthy leukocytes in alligators, these compounds were employed in whole blood instead of leukocyte preparations commonly used in other studies. The detection of superoxide was concentration- and time-dependent and linear with serial dilutions of whole blood. WST-1 reduction was inhibited by superoxide dismutase, indicating that the reduction was due to the presence of superoxide. Light microscopy revealed that superoxide production occurred in leukocytes, with no detectable contributions from other blood components. 相似文献
44.
Reactive oxygen species (ROS) are hypothesized to play a role in the sonoporation mechanisms. Nevertheless, the acoustical phenomenon behind the ROS production as well as the exact mechanisms of ROS action involved in the increased cell membrane permeability are still not fully understood. Therefore, we investigated the key processes occurring at the molecular level in and around microbubbles subjected to ultrasound using computational chemistry methods. To confirm the molecular simulation predictions, we measured the ROS production by exposing SonoVue® microbubbles (MBs) to ultrasound using biological assays. To investigate the role of ROS in cell membrane permeabilization, cells were subjected to ultrasound in presence of MBs and plasmid encoding reporter gene, and the transfection level was assessed using flow cytometry. The molecular simulations showed that under sonoporation conditions, ROS can form inside the MBs. These radicals could easily diffuse through the MB shell toward the surrounding aqueous phase and participate in the permeabilization of nearby cell membranes. Experimental data confirmed that MBs favor spontaneous formation of a host of free radicals where HO was the main ROS species after US exposure. The presence of ROS scavengers/inhibitors during the sonoporation process decreased both the production of ROS and the subsequent transfection level without significant loss of cell viability. In conclusion, the exposure of MBs to ultrasound might be the origin of chemical effects, which play a role in the cell membrane permeabilization and in the in vitro gene delivery when generated in its proximity. 相似文献
45.
We found that the interaction of paramagnetic centers that have different relaxation times differs fundamentally from the
interaction of centers having close relaxation times. Simulation showed that in this case there is an anomalous redistribution
of the spectral-line intensity from the center to the wings with a virtually preserved distance between extremal points (super-Lorentzian
shape of the line), which leads to underestimation of the total intensity recorded. The results obtained make it possible
to explain a number of aspects of the radiospectroscopy of carbon materials of practical importance such as the nature of
the generally accepted maximum on the curve for the dependence of the total intensity of an EPR signal on the temperature
of the heat treatment of organic compounds and the degree of metamorphism of natural coals, the specific features of the effect
of oxygen molecules and paramagnetic ions of metals on the EPR spectra of carbon materials, etc.
Belarusian State University, 4, F. Skorina Ave., Minsk, 220080 Belarus. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 65, No. 2, pp. 224–229, March–April, 1998. 相似文献
46.
A Mössbauer study of cation distribution in systems Co x Mn3?x?y Fe y O4 and Ni x Mn3?x?y Fe y O4 has been made. It has been found that in both systems all specimens withy<0.6 value exhibit quadrupole doublets corresponding to site symmetries Fe3+(I) and Fe3+(II) of octahedral site. As more and more cobalt or nickel is introduced into the matrix the intensity of the inner quadrupole doublet increases while on introducing iron that of the outer quadrupole doublet increases. After a certain concentration of iron the inner doublet starts becoming more intense. It is suggested that this arises possibly from the substitution of cations in the second co-ordination sphere of Fe3+(I) and Fe3+(II) sites. Fory>0.6 the Mössbauer spectra show relaxation effects. 相似文献
47.
Masahito Tagawa Kumiko Yokota Koji Matsumoto Yuden Teraoka Masahito Niibe 《Applied Surface Science》2010,256(24):7678-7683
Surface structural changes of a hydrogenated diamond-like carbon (DLC) film exposed to a hyperthermal atomic oxygen beam were investigated by Rutherford backscattering spectroscopy (RBS), synchrotron radiation photoelectron spectroscopy (SR-PES), and near-edge X-ray absorption fine structure (NEXAFS). It was confirmed that the DLC surface was oxidized and etched by high-energy collisions of atomic oxygen. RBS and real-time mass-loss data showed a linear relationship between etching and atomic oxygen fluence. SR-PES data suggested that the oxide layer was restricted to the topmost surface of the DLC film. NEXAFS data were interpreted to mean that the sp2 structure at the DLC surface was selectively etched by collisions with hyperthermal atomic oxygen, and an sp3-rich region remained at the topmost DLC surface. The formation of an sp3-rich layer at the DLC surface led to surface roughening and a reduced erosion yield relative to the pristine DLC surface. 相似文献
48.
血液可见吸收光谱与血氧参数神经网络估算法 总被引:1,自引:0,他引:1
总血红蛋白浓度和血氧饱和度是两个基本的血氧参数。文章提出了利用内置双光纤微创探头在位测量大鼠脑组织血氧参数的新方法。首先,利用悬乳液(Intralipid)和全血配置不同总血红蛋白浓度的混合溶液,模拟生物组织模型,用光纤光谱仪测试系统测量组织模型在加氧和去氧时的实时吸收光谱,同时用血氧分析仪(OXI meter)对血氧参数定标,建立测试光谱和定标数据样本集。然后,利用人工神经网络建立血液吸收光谱与血氧参数的神经网络模型,训练后的网络模型能根据吸收光谱输出生物组织的血氧参数值,总血红蛋白浓度和血氧饱和度的平均输出误差分别为±4μmol·L-1和±5%。最后,利用神经网络模型对大鼠脑组织血氧参数进行了在位测试实验,测得脑灰质的血氧饱和度为0.60~0.70,脑白质血氧饱和度为0.45~0.55;总血红蛋白浓度在脑皮层(深度1mm)附近最高,平均110μmol·L-1,其余深度脑组织的总血红蛋白浓度为70~90μmol·L-1。这种方法对脑外科微创手术中实时在位测试脑组织血氧参数具有重要的参考意义。 相似文献
49.
The protein, hen egg white lysozyme, on photoexcitation undergoes electron transfer with menadione (2-methyl-1,4-naphthoquinone), a widely known anticancer drug. With the addition of menadione the fluorescence of lysozyme is quenched with the simultaneous formation of an excited state charge-transfer complex in the longer wavelength and a ground state complex. The former is further evident from laser flash photolysis studies, which indicate a tryptophan to menadione electron transfer. From fluorescence quenching studies the binding constant is found to be ∼1.7×104 M−1 with the corresponding changes in enthalpy (ΔH°) and entropy (ΔS°) as 12.24 kJ mol−1 and 124.12 J mol−1 K−1, respectively, indicative of an entropy-driven process. The circular dichroism studies also show some structural changes with increase in α-helical content in the protein on interaction with menadione. Finally, docking studies give some insight into the role of Trp 108 of lysozyme in the interaction. 相似文献
50.
用相对速率方法分别考察了OH自由基与DMS在氮气、空气和氧气体系的反应速率常数. 发现使用HONO和CH3ONO作为OH自由基发生剂时,基态氧原子O(3P)对动力学的测定有很大的影响. H2O2为OH自由基的发生剂,室温下在氮气、空气及氧气体系下的速率常数分别为4.50×10-12,8.56×10-12和11.31×10-12 cm3/(molecule?s).在287~338 K,测得氮气和空气体系下的阿累尼乌斯表达式分别为:kair=(7.24±0.28)×10-13exp[(770.7±97.2)/T],kN2=(3.40±0.15)×10-11exp[-(590.3±165.9)/T 相似文献