Nitrogen-containing compounds are one important class of constituents in tobacco because of various pharmacological and biological properties. Three types of tobacco leaves (burley, bright, and oriental) were studied using solid-state (15)N NMR cross polarization with magic-angle spinning, dipolar dephasing and five pi replicated magic angle turning (FIREMAT) experiments. The results show that burley tobacco leaves contain significantly more pyridinic nitrogen than that of bright or oriental tobacco leaves. The principal values of (15)N chemical shift tensors of nitrogen functional groups were obtained from the FIREMAT data. Possible assignments of solid-state (15)N NMR resonances were made using nitrogen chemical shift tensors in some model compounds or isotropic chemical shift values from liquid NMR results. To the best of our knowledge, this is the first solid-state (15)N NMR study of tobacco plant material.

Cobalt catalysts supported on silica aerogel have been prepared using sol–gel chemistry followed by drying under supercritical ethanol conditions. Three different loadings of cobalt were synthesized: 2, 6, and 10% by weight. Transmission electron micrographs indicate that the metallic cobalt exists as discrete particles 50–70 nm in diameter for the 2 and 6% loadings. The 10% catalyst shows long needles of cobalt. BET and BJH measurements indicate that the catalysts retain the silica aerogel properties of high surface area (∼800 m2/g), large pore volume (∼5 cm3/g), and an average pore diameter in the mesoporous regime (∼25 nm). The catalysts were evaluated for Fischer–Tropsch activity in a laboratory-scale packed bed reactor. All three catalysts were active with the 10% Co catalyst achieving more than 20% CO conversion which corresponds to a rate of 1.53 g CO per g-cat per hour. The catalysts were selective for the C10+ hydrocarbons with more than 50% of the carbon contained within this fraction. A significant portion of the C9–C15 hydrocarbon product was observed as 1-olefins which reflects the enhanced mass transport within the very porous aerogel support.

The LixV2O5 cathode of Li-rechargeable battery cells under three different charge states have been studied by high-resolution solid-state Li-7 magic angle spinning (MAS) NMR spectroscopy. In the charged and discharged states, three different Li-7 NMR resonances, corresponding to the Li+ ions in the electrolyte, in the V2O5 cathode, and on the surface of the V2O5 cathode, were identified by their spin-lattice relaxation times in inversion recovery experiments. Only signals of the Li+ ions in the electrolyte were observed in the over charged state. It is shown experimentally that the Li+ ions in the electrolyte experience a dynamics or exchange process in a time scale of milliseconds with those in the V2O5 cathode, in particular for the discharged state, where a severe cross relaxation effect was observed in the inversion recovery for the Li+ ions in the electrolyte. It is concluded that such an exchange is mediated by the Li+ ions on the surface of the V2O5 cathode. Therefore, the surface structure of the V2O5 cathode electrode plays an important role in the reversibility of the Li+ ions in the rechargeable battery.

A series of hydrous ruthenium oxide (RuO2.xH(2)O) samples annealed at different temperatures have been studied by solid-state H-1 NMR spectroscopy. The proton dynamics of the RuO2.xH(2)O samples was characterized for the first time through variable-temperature H-1 spin-lattice relaxation time (T-1) measurements. For the RuO2.xH(2)O samples annealed at temperatures lower than 100 degreesC and higher than 200 degreesC, a high proton activation energy was obtained, implying that the proton dynamics/diffusive motion is relatively restrained, whereas the samples annealed at temperatures between 100 and 200 degreesC exhibited relatively low proton activation energies, indicating that the protons can easily diffuse into the bulk of the material. Therefore, the proton activation energy correlates strongly with the hydrogen transfer and storage ability of the proton-conducting materials. In combination with electrochemical measurements, our NMR data also suggest that the coexistence of the Ru2+, Ru-3+,Ru- and Ru4+ valency states in the local structure of the RuO2.xH(2)O is crucial for hydrogen transfer and storage ability.

The morphologies and crystalline structures of RuO(2.)xH(2)O with different contents of water (x) were investigated using transmission electron microscope (TEM) and selected area electron diffraction (SAED) techniques, respectively. From the SAED patterns, it was found that RuO(2.)xH(2)O powders were amorphous phase at low annealing temperatures; however, became crystalline phase after annealed at high temperatures. The structure disorder brought about by proton insertion was obtained by SAED pattern from a sample annealed at the transition temperature from amorphous to crystalline phases. The proton dynamics inside RuO(2.)xH(2)O was studied by solid-state H-1 nuclear magnetic resonance (NMR) spectroscopy at various temperatures. It was demonstrated that the activation energy of proton in RuO(2.)xH(2)O samples is directly associated with the proton transport and storage ability of these materials. A model of proton diffusion in amorphous RuO(2.)xH(2)O was proposed to explain the relationship between the specific capacitance and the structural water content in RuO(2.)xH(2)O materials.

Amorphous hydrous ruthenium oxide (RuO2·xH2O) with different composition x has been studied using solid-state nuclear magnetic resonance (NMR) spectroscopy. The 2DNMR spectra at different temperatures illustrate that the water molecules undergo fast molecular motion even if the temperature is as low as 213 K. The static 1HNMR spectra indicate the composition dependent proton–proton dipolar interaction. It is demonstrated that the mobility of the water molecules and their interaction with ruthenium oxides play an important role in the proton charge density. In conclusion, the competition between these two antithetical effects provides a mechanism for the proton charge storage of the RuO2·xH2O materials.

The scavenging effect of rhodiola rosea L. and radix salviae miltiorrhizaeon active oxygen radicals (O-2(-.) and (OH)-O-.) was studied by single sweep oscillopolarography. Superoxide anion radical was produced by the autoxidation. of pyrogallol. Hydroxyl radical was generated from the Fenton system. Phenyl-tert-butylnitrone (PBN) spin trap was used to trap the hydroxyl radical. The spin adduct could be determined by-single sweep oscillopolarography. Rhodiola rosea. L. and radix salviae miltiorrhizae showed scavenging effect bn O-2(-.) and (OH)-O-.. The scavenging effect of radix salviae miltiorrhizae: was stronger than that of rhodiola rosea L.. The scavenging ability on O-2(-.) was:salidroside > Jilin Changbaishan rhodiola > Tibet rhodiola, and radix: salviae miltiorrhizae > Anguo salvia miltiorrhiza bge. (I) > Anguo salvia miltiorrhiza bge., (II). While for (OH)-O-., the scavenging ability was in the order of the following: salidroside > Jilin Changbaishan rhodiola > Tibet rhodiola, and Anguo - salvia miltiorrhiza bge. (II) > Anguo salvia miltiorrhiza bge. (I) > radix salviae miltiorrhizae, Their IC50 values were calculated respectively.

An electrochemical method combined with spin trapping was applied in the determination of hydroxyl radicals. Hydroxyl radicals were generated by the Fenton reagent, i.e. an iron–EDTA complex reacting with H2O2 in the presence of ascorbic acid. The spin trap reagent phenyl-tert-butyl nitrone (PBN) was used to trap the hydroxyl radicals, and the free radical adduct of PBN could be detected by single sweep oscillopolarography, with its second order derivative cathodic wave at −0.52V vs SCE. The electrochemical behavior of the PBN adduct was investigated by single sweep oscillopolarography and cyclic voltammetry. An electron spin resonance (ESR) experiment was made in order to verify the existence of the PBN spin adduct in the Fenton system. The experimental conditions for the measurement were optimized, and then the scavenging effect of some compounds on hydroxyl radicals was also studied.

目的 :研究枸杞子和黄精对活性氧自由基 （O-·2 和·OH ）的清除作用。方法 :通过邻苯三酚在碱性环境下自氧化产生O-·2 ,Fenton体系产生·OH ,自旋捕集剂PBN捕捉产生的·OH。单扫示波极谱法检测枸杞子和黄精对O-·2 和·OH的抑制作用。结果 :枸杞子和黄精对O-·2 和·OH具有明显的抑制作用。分别计算了它们的IC50 值。枸杞子对O-·2 和·OH的清除能力为 :同仁堂宁夏枸杞 ＞市售宁夏枸杞 ＞河北枸杞 ＞内蒙枸杞。黄精对O-·2 和·OH的清除效能力 :酒制黄精 ＞蜜炙黄精。结论 :枸杞子和黄精都能有效地清除活性氧自由基 （O-·2 ,·OH）具有抗氧化作用 ,可能是它们所具有的抗氧化等药理作用机理之一。

OBTECTIVE: The scavenging effect of Fructus Lycii and Rhizoma Polygonati on active oxygen free radicals (O2 .- and OH) was investigated. METHOD: The superoxide anion radical was produced by the autoxidation of pyrogallol in alkaline solution, and the hydroxyl radical was generated from the Fenton system. Phenyl-tert-butylnitrone (PBN) spin trap was used to trap the hydroxyl radical. Single sweep oscillopolarography was applied to detect the generation of O2 .- and ·OH. RESULTS: Fructus Lycii and Rhizoma Polygonati had obvious inhibitory effect on O2 .- and OH. Their IC50 values were calculated respectively. The scavenging ability of Fructus Lycii on O2 .- and ·OH was: Tongrentang Fructus Lycii barbari > than on market > Hebei Fructus Lycii > that of Nei Mongol Fructus lycii. The scavenging effect of Rhizoma Polygonati on O2 .- and ·OH was polygonatum mix-fried with wine was stronger than that of polygonatum mix-fried with honey. CONCLUSION: Fructus Lycii and Rhizoma Polygonati could scavenge the active oxygen radicals (O2 .-, ·OH) effectively,and they had antioxidative effect. The scavenging effect on free radicals of Fructus Lycii and Rhizoma Polygonati was probably part of their pharmacological mechanism.

A novel, simple and convenient method for the determination of hydroxyl radicals is established. Hydroxyl radicals produced by Fenton reaction is trapped by spin trap reagent phenyl-t-butyl nitrone (PBN), and the free radical adduct of PEN can be detected by single sweep oscillopolarography, with its second order derivative cathodic wave at -0.52V vs SCE. The optimum experimental conditions for the determination is discussed, and the scavenging effects of some compounds on OH was also studied.

OBJECTIVE: To investigate the anti-superoxide anion radical effect of quercetin, rutin, VC, VE. METHODS: The single sweep oscillopolarography method was applied to determine the O2/.- that was produced by the autoxidation of pyrogallol. RESULTS: Quercetin and rutin inhibited the formation of O2/.- effectively, however, the scavenging ability of rutin was weaker than that of quercetin, and their IC50 was 17.8 μmol·L-1 and 16.3 μmol·L-1 respectively. The difference of scavenging effect of these two compounds can be interpreted from their chemical structures. The inhibitory rates of VC and VE at the same concentration were 76.8%, 25.7% respectively CONCLUSIONS: Quercetin and rutin are flavonoid and effective superoxide radical scavengers. The scavenging effect of flavonoids on superoxide anion radical can be determined directly by electrochemistry method. The scavenging effect of VC on O2/.- is stronger than that of VE in this system.

NMR imaging is a new NMR technique which appeared in these twenty years. The most important difference from the traditional NMR technique is that it can distinguish what signals will be provided by which part of the sample. Since Lauterbur reported the first NMR imaging in 1973, this technique has been widely used in biological, medical, geological, and material studies. NMR imaging technique has also been used in the study of coal structure in recent

核磁共振成象是近20年来出现的一种新的核磁共振技术。自从1973年Lauterbur发表第一篇核磁共振成象（NMRI）论文以来,这一技术发展很快,已得到广泛的应用。近几年,核磁共振成象技术也开始应用于煤结构的研究中。然而,由于煤是一种非常复杂的天然有机物质,同时在固体煤中质子间存在有强的自旋偶极-偶极相互作用能使T 2 值变小,并且导致谱线增宽,因此限制了成象的分辨率。目前有关煤的核磁共振成象的文献报道的很少。Dieckman等人通过使用多脉冲质子去偶技术和投影重建核磁共振成象方法,获得了几个干燥煤样的二维核磁共振图象,并区分了他们的基本微观结构。空间分辨率约为200μm。我们用吡啶饱和蒸气处理了抚顺西露天长焰煤和老虎台气煤等几种煤,通过质子密度成象,观察了进入煤样中的溶剂的分布情况,并获得了一些有关煤结构的信息。

The permeation, transportation and swelling behavior of solvents into coal are investigated by NMR imaging using pyridine-ds and acetone-d6. Images of coal swollen with deuterated solvents illuminate proton distributions of mobile phases within the coal macromolecular networks. More information about the chemical and physical structure of coal can be obtained using NMR imaging techniques.

Solvent transport into coal was studied by proton NMR imaging using pyridine - d(5) and acetone - d(6). Solvent swelling of Fushun bituminous coal was also observed by proton spin density images. From these NMR images, some information on the transport and swelling behavior of coal was obtained.