CeO2纳米晶的光伏特性和量子尺寸效应

对制备的ＣｅＯ２纳米晶进行了反射吸收光谱研究，对其在３００－４５０ｎｍ的宽带吸收指认为Ｏ２ｐ→Ｃｅ４ｆ电荷转移跃迁，发现这个吸收带随着样品粒径变小而红移，利用表面光电压谱方法和场调制表面光电压谱方法不同粒径的ＣｅＯ２纳米晶的光伏特性进行了研究。并对吸收谱带进行了解析。当样品粒径达到纳米尺寸时，在ＣｅＯ２价带上大约０．９ｅＶ处明显地形成一个新能带。这个能带具有较强的定域性，在相应的跃迁的过程中产生具     

阴离子X~-(F~-、Cl~-、Br~-)对中孔分子筛MCM-41合成与性质的影响

在凝胶体系ＮａＸ（Ｆ、Ｃｌ、Ｂｒ）Ｎａ２ＯＡｌ２Ｏ３ＳｉＯ２ＣＴＡＢ（十六烷基三甲基溴化铵）Ｈ２Ｏ中，研究了水热合成中孔ＭＣＭ４１的合成条件。实验证明，在３９８Ｋ下晶化８～１６ｄ，ＮａＸ／ＳｉＯ２介于０．０１～０．０５时，均可合成出ＭＣＭ４１分子筛；ＮａＦ的加入，可以加快ＭＣＭ４１分子筛的晶化速度；ＮａＢｒ的加入，对形成ＭＣＭ４１分子筛有阻碍作用。采用ＸＲＤ、ＳＥＭ、ＴＧＤＴＡ和Ｎ２吸附对合成样品加以表征，证明合成样品具有介孔分子筛特性。     

中孔MCM—41分子筛在微孔沸石ZSM—5上附晶生长的研究

首次在微孔沸石ＺＳＭ５表面进行了ＭＣＭ４１分子筛的附晶生长，并首次提出中孔材料ＭＣＭ４１分子筛静电组配理论的新形式（ＸＳ＋Ｉ）；同时利用ＸＲＤ、ＴＥＭ、ＢＥＴ等测试手段表征了合成样品，并讨论了微孔沸石表面附晶生长中孔分子筛ＭＣＭ４１的合成化学，考察了Ｆ离子效应、ｐＨ值及表面活性剂ＣＴＡＢ（十六烷基三甲基溴化铵）的影响。     

EFFECT OF CRYSTALLIZATION TEMPERATURE ON MCM-41 SYNTHESIS

在Ｎａ２ＯＳｉＯ２ＣＴＡＢＨ２Ｏ四元水热体系中系统地考察了晶化温度对中孔ＭＣＭ４１分子筛合成及其骨架结构的影响。实验结果表明，提高晶化温度虽然能明显加快晶化速率，缩短晶化时间，但同时样品的结晶度和中孔骨架结构的有序度却被迅速破坏。这些特点与传统沸石的合成过程完全不同，其原因主要是合成ＭＣＭ４ｌ时所用的模板剂及其在合成中所起的模板作用与传统沸石完全不同。相对低的晶化温度（如１００℃）有利于高质量和高热稳定性的中孔ＭＣＭ４ｌ分子筛的合成。     

AlSiMCM－41中孔分子筛的合成及其机理研究

以水玻璃、偏铝酸钠、ＣＴＡＢ为原料，研究了合成条件对制备中孔沸石分子筛ＭＣＭ－４１样品的影响，并讨论了孔道结构形成机理。实验表明层状相可向六角形相转变，但晶化时间过长，所得产物具有热不稳定的结构     

AlSiMCM-41中孔分子筛的合成及其机理研究

以水玻璃、偏铝酸钠、ＣＴＡＢ为原料，研究了合成条件对制备中孔沸石分子筛ＭＣＭ－４１样品的影响，并讨论了孔道结构形成机理。实验表明层状相可向六角形相转变，但晶化时间过长，所得产物具有热不稳定的结构。     

含Ce的水热体系中结构稳定性及变价现象

利用ＸＲＤ、ＩＲ及ＸＰＳ谱研究了含Ｃｅ的水热体系中产物及其经过各种后处理的样品结构稳定性及Ｃｅ离子的价态变化。结果表明，不同的原料导致Ｃｅ离子稳定于不同的价态，如直接形成包括纳米晶在内的ＣｅＯ２及一新相ＣｅＯＨＣＯ３，样品ＣｅＯＨＣＯ３经２ＧＰａ的冷压处理未发生结构转变，经高温焙烧处理得到具有高结晶度的棕红色的ＣｅＯ２，当初始原料为Ｃｅ２（ＳＯ４）３和Ｃｅ（ＮＯ３）３时，产物为ＣｅＯ２；而当初始原     

Cu—Nd（Ce,La）—Al合金及Raney Cu—Nd（Ce,La）催化剂的XRD研究

采用ＸＲＤ表征手段对不同稀土元素不同组成的Ｃｕ－Ａｌ－Ｍ（Ｍ＝Ｎｄ，Ｃｅ和Ｌａ）合金及其碱抽提产物ＲａｎｅｙＣｕ－Ｍ催化剂的体相结构进行了表征，发现所有Ｃｕ－Ａｌ－Ｍ合金均形成有二元ＣｕＡｌ２和三元ＣｕＭＡｌ８的两种晶相，随着稀土元素含量的增中，三元Ｃｕ，ＭＡｌ８晶相逐渐增多。而且其中的Ａｌ难于ＣｕＡｌ２中的Ａｌ的抽提，ＲａｎｅｙＣｕ－Ｍ催化剂中只存在金属铜的晶相，未形成Ｃｕ－Ｍ晶相，而一随着Ａｌ     

纯硅MCM-41中孔分子筛合成因素的研究Ⅱ.表面活性剂对合成的影响

分别用表面活性剂十六烷基三甲基溴化胺（１６３１）和十八烷基三甲基溴化铵（１８３１），采用室温法和水热晶化法合成了纯硅ＭＣＭ４１中孔分子筛，利用ＸＲＤ、ＦＴＩＲ等技术探讨了两种表面活性剂对ＭＣＭ４１的合成及产物特性的影响。结果表明，用１６３１作为表面活性剂时，合成的ＭＣＭ４１样品具有晶化速率快、晶胞参数小和热稳定性较好的特点；而用表面活性剂１８３１时，合成的ＭＣＭ４１晶胞参数较大、水热稳定性及耐强酸性优良     

Co／γ—Al2O3催化剂上肉桂醛的选择加氢：催化剂的表征

采用ＸＲＤ,ＴＰＲ,ＸＰＳ技术,分别研究了Ｃｏ３Ｏ４／γ－Ａｌ２Ｏ３样品的晶相结构,还原性能及表面状态,ＸＲＤ结果表明,不同前驱物的钴负载于γ－Ａｌ２Ｏ３后,钴是以Ｃｏ３Ｏ４的结构存在,还原后的钴皆以α－Ｃｏ的形式存在,但以ＣｏＣｌ２为前驱物时,还原后的样品中钴的晶粒较大。     

Temperature quenched DODAB dispersions: fluid and solid state coexistence and complex formation with oppositely charged surfactant

Dilute dispersions of the synthetic bilayer forming double-chained cationic lipid dioctadecyldimethylammonium bromide (DODAB) were investigated. In dispersions sonicated above the chain melting temperature Tm (approximately 45 degrees C) it was found by H NMR that about 50% of the surfactant chains remained fluid when the samples were cooled to room temperature, which is 20 degrees C below Tm. In contrast, there was no sign of a fluid fraction in unsonicated samples at room temperature. The addition of the anionic surfactant sodium dodecyl sulfate (SDS) to DODAB dispersions at room temperature resulted in the formation of an essentially stoichiometric DODA-DS complex with frozen chains, as seen by titration calorimetry and H NMR experiments. For sonicated samples, turbidity experiments demonstrated that, after a fast complexation reaction, the system remains colloidally stable unless the SDS-to-DODAB mixing ratio is too close to unity. H NMR experiments also showed that in the unreacted DODAB the fraction of fluid chains remained close to 50%, indicating either that SDS reacts equally fast with fluid and frozen DODAB or that there is a relaxation of the fluid fraction after the complexation. The melting enthalpy and the melting temperature of the alkyl chains rise gradually as the mixing ratio increases. We observed with cryo-TEM that the fraction of large unilamellar vesicles was significantly larger after addition of SDS. This indicates vesicle fusion. Based on both wide- and small-angle X-ray scattering patterns, the structure of the equimolar SDS-DODAB complex at 25 degress C was proposed to be lamellar.     

Modifications of the 1H NMR metabolite profile of processed mullet (Mugil cephalus) roes under different storage conditions

¹H NMR spectroscopy was employed to study the modifications over time of the water‐soluble low molecular weight metabolites extracted from samples of salted and dried mullet (Mugil cephalus) roes (mullet bottarga) stored at different conditions. Samples of grated mullet bottarga were stored for 7 months at ?20 °C, at 3 °C, and at room temperature in the presence and in the absence of light and then timely extracted and analyzed by NMR. Principal component multivariate data analysis applied to the spectral data indicated that samples stored at ?20 °C maintained similar features over time whereas, along PC1, samples stored at room temperature in the presence and in the absence of light showed, over time, marked metabolite modifications. The comparative analysis of the integrated areas of the selected regions of the ¹H NMR spectra indicated that the major compositional changes due to storage conditions were (i) the increase of the derivatives of the breakdown of phosphatidylcholine (choline, phosphorylcholine, and glycerol), (ii) the breakdown of nucleosides, (iii) the decrease of methionine, tryptophan, and tyrosine, and (iv) the cyclization of creatine. These changes were observed at different storage conditions, with more pronounced trends in the samples stored at room temperature. The role of metabolites in food aging is discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

(23)Na multiple-quantum MAS NMR of the perovskites NaNbO(3) and NaTaO(3)

The distorted perovskites NaTaO(3) and NaNbO(3) have been studied using (23)Na multiple-quantum (MQ) MAS NMR. NaTaO(3) was prepared by high temperature solid state synthesis and the NMR spectra are consistent with the expected room temperature structure of the material (space group Pbnm), with a single crystallographic sodium site. Two samples of NaNbO(3) were studied. The first, a commercially available sample which was annealed at 900 degrees C, showed two crystallographic sodium sites, as expected for the room temperature structure of the material (space group Pbcm). The second sample, prepared by a low temperature hydrothermal method, showed the presence of four sodium sites, two of which match the expected room temperature structure and the second pair, another polymorph of the material (space group P21ma). This is consistent with powder X-ray diffraction data which showed weak extra peaks which can be accounted for by the presence of this second polymorph. Density functional theory (DFT) calculations support our conclusions, and aid assignment of the NMR spectra. Finally, we discuss the measured NMR parameters in relation to other studies of sodium in high coordination sites in the solid state.     

Texture and molecular chain mobility in cold-deformed linear polyethylene

The fine texture and molecular motion in rolled (draw ratios λ = 2, λ = 5), cold-drawn (λ = 6), and hot-drawn (λ = 6), linear polyethylene (Sholex 6050) films were studied by small-angle x-ray scattering, wide-line nuclear magnetic resonance (NMR), and dynamic viscoelastic measurements. NMR spectra of the rolled (λ = 5) and cold-drawn samples show a small narrow component at room temperature. For these cold-deformed samples, a gradual decrease in the second moment is observed well below the α relaxation temperature and a new relaxation appears in the same temperature region in the logarithmic decrement versus temperature. This relaxation is absent in the original and hot-drawn samples. It is concluded that the new relaxation arises from molecular motion in intermediate regions where molecular chains are less mobile than in the amorphous state.     

Aqueous-mediated green synthesis of 3-carboxyxoumarins using grinding technique

A simple, efficient and green procedure for the synthesis of 3-carboxycoumarins has been developed which involves the grinding of 2-hydroxybenzaldehydes with Meldrum's acid (2,2-dimethyl-1,3-dioxan-4,6-dione) in aqueous moist conditions at room temperature. The protocol is much more efficient as the reactions are carried out at room temperature and yields are also quite high. All the compounds were characterized by their IR, ¹H NMR and mass spectral data and compared with authentic samples.     

A29Si NMR study of natural and synthetic melanophlogites,the silica analogues of the clathrate hydrates of type I

²⁹Si MAS NMR spectra of natural melanophlogite as well as of synthetic melanophlogite indicate that the room temperature lattice structure has lower symmetry than expected from its proposed crystal structure. On heating the samples to temperatures above room temperature, the structure undergoes a reversible phase transition with a transition temperature characteristic of the locality. For the synthetic melanophlogite, the transition is over the range 298 K to 338 K. From low temperature NMR spectra it is concluded that the low temperature forms of synthetic melanophlogite and of melanophlogite from Sicily differ in their crystal lattice symmetries due to their characteristic guest species.Dedicated to Dr D. W. Davidson in honor of his great contributions to the sciences of inclusion phenomena.On leave Mineralogisches Institut, CAU KIEL, FRG     

Spatially resolved NMR in polymer science

Selected applications of spatially resolved NMR are presented, which demonstrate the use of the method for investigating applied topics relevant to polymer and materials science. Examples are given for imaging of rigid, soft, and fluid matter. They include characterization and interpretation of electrical aging in poly(ethylene), cross-link density at the interface of covulcanized elastomer sheets, and cross-filtration in hollow-fiber filter modules. A novel NMR detector, the NMR-MOUSE, has been developed for process and quality control by relaxation measurements. Its use for non-destructive determination of the glass-transition temperature by room temperature measurements on elastomer samples is demonstrated.     

Dynamics of polypropene and propene-ethylene copolymers at temperatures above ambient

Several applications of solid-state nuclear magnetic resonance (NMR) spectroscopy to studying polyolefin mobility at temperatures ranging from room temperature to above the polymer melt are described. 13_C NMR can be used with magic-angle spinning and high-power proton decoupling to determine the fraction of mobile polymer in polypropene and to characterize the nature of the polymer chain motions as a function of sample temperature. Similar techniques can be used to characterize the local motions of complex copolymer systems such as heterophasic ethylene-propene copolymers. The practicality of low-speed magic angle spinning to observe quantitative high-resolution NMR spectra of neat, molten polymer samples is also described.     

NMR and impedance spectroscopy data on the ionic mobility and conductivity in PbSnF4 doped with alkali metal fluoride

NMR and impedance spectroscopy are used to study the ionic mobility and conductivity in crystalline samples in PbSnF₄-MF systems (M = Li, Na, K) in a 150?C473 K temperature range. The ¹⁹F NMR spectral parameters, types of ionic motion, and ionic conductivity value in the PbSnF₄ compound doped with alkali metal fluoride is found to be determined by the temperature, nature, and concentration of an alkali cation. The specific conductivity of the crystalline samples in PbSnF₄-MF systems (M = Li, Na, K) is rather high at room temperature and hence, it seems possible to apply them in the development of functional materials with high ionic (superionic) conductivity.