一种计算稀土材料陷阱深度的新方法

表征陷阱材料的主要物理量是陷阱深度, 准确计算出陷阱深度对于研究陷阱材料具有重要的意义. 从能带模型出发, 利用速率方程分析了整个热释光过程, 提出了一种计算稀土材料陷阱深度的新方法, 替代以往利用单分子或双分子近似计算陷阱深度的方法. 以SrAl2O4：Eu^2＋, Dy^3＋及Sr4Al14O25：Eu^2＋, Dy^3＋材料为研究对象, 计算了陷阱深度. 研究表明, 这种计算方法能更准确、真实地描述其物理过程.     

几个金属卤素簇的合成与性能研究

The hydrothermal reaction of CuBr2 and CuBr with phen·H2O （phen= 1,10-phenanthroline） in a molar ratio of 1：1：1.5 gave birth to the first copper-halo cationic cluster [Cu2^Ⅱ Cu2^Br4 （phen）4 ] ^2＋（1） with tetranuclear anionic cluster [Cu4Br6]^2-. Changing the precursors or their molar ratios, two mononuclear complexes [Cu（phen）2Br]Br·H2O （2） and [Ni（phen）3][CuCl2]2 （3） as well as two unusual copper-halo chains found in polymers [Cu2Br2（phen）]∞ （4） and [Cu^ⅡCu3^ⅠBr2Ⅰ3 （phen）2 ]∞ （5） were obtained. The （Cu2Br2）∞ chain of 4 looks like a linearar ray of hexagons based on fused Cu3Br3 units, and the linear （Cu3Ⅰ3Br^-）∞ chain of 5 is an alternate combination of the rhombic Cu2I2 cores and the Cu4I4Br2^2- units. In addition, the hydrothermal reaction of CuBr2 with NA（NA=nicotinic acid） or INA （INA =isonicotinic acid） resulted in the syntheses of two compounds [CuBr（NA）] （6） and [CuBr（INA）]∞（7） containing staircase chain. Among them the third-order non-linear optical properties of 2, 5, 6 and 7 were investigated and all exhibit the reverse saturable absorption （α2〉0） and self-defocusing performance （n2〈0）.     

Micro construction of poly(epsilon-caprolactone)/poly(L-lactic acid) blend film by solution casting under microwave irradiation

The micro construction of poly(epsilon-caprolactone) (PCL) and poly(L-lactic acid) (PLLA) blend films fabricated by solution casting under microwave irradiation was investigated by selective enzymatic degradation and scanning electron microscopy (SEM). The results were totally different from the blends obtained by conventional methods. The blend was more homogeneous and the PCL continuous phase more compact as no spherulites and tiny zone separation were observed from the film surface and no PCL network was observed inside the film, and the degradation of a PCL plank by Pseudomonas lipase was significantly retarded. The distributed PLLA micro spheres were enlarged and amorphous. The thermal behavior of the blend by microwave heating revealed that PCL and PLLA underwent a melting process, which induced the variations of the PCL phase and PLLA spheres. The weight loss caused by degradation of the PCL/PLLA blend obtained by conventional methods (B50c) is greater than that of the blend obtained by microwave methods (B50m), which reflects the change in morphology from a loose PCL network (B50c) to a dense PCL plank (B50m).     

Generation and reactions of substituted phenide anions in an electrospray triple quadrupole mass spectrometer

Substituted benzoic acid anions undergo decarboxylation in the medium-pressure region of an electrospray ion source yielding in most cases the correspondingly substituted phenide anions in high yield. The location of the anionic center is specified by the position of the carboxylic group. The only exceptions are compounds with substituents containing acidic hydrogen atoms, like OH and NH(2) groups. For such compounds, either an intra- or an intermolecular (mediated by the molecules of methanol or water) proton transfer from the more acidic position to the benzene ring is observed. The generated anions can be selected using the first quadrupole for studying their ion-molecule chemistry in the second quadrupole of a triple quadrupole mass spectrometer. Their reactions with CO(2), O(2), CH(3)COCH(3) and CCl(4) may serve as typical examples. The general applicability of this method for the generation of phenide anions has been confirmed on three different mass spectrometers. Experiments performed using carboxylic acids other then benzoic acid and its derivatives show that this method is not limited to phenide anions and can be used for the generation of a much wider range of carbanions in the gas phase.     

Studies of poly-<Emphasis Type="Italic">L</Emphasis>-lysine-starch nanoparticle preparation and its application as gene carrier

Anion starch nanoparticle (StNP) with a diameter of 50 nm was prepared in water-in-oil microemulsion, with soluble starch as raw materials and POCl₃ as crosslinking agent. PLL-StNP was prepared by linking poly-L-lysine (PLL) on the surface of StNP. At the same time, the size of PLL-StNP and its stability in aqueous solution were checked by AFM. The analysis of plasmid DNA binding, DNase I enzymatic degradation, toxicity and transfection were done. We discovered that PLL-StNP may be used as non-virus nanoparticle gene carrier. And we developed the method of preparing PLL-StNP gene carrier and used it in cell transfection. As non-virus gene carrier, PLL-StNP has some advantages, such as large load of DNA, high transfection efficiency, low cell toxicity and biodegradability.     

Sunlight-activated AlFeO3/TiO2 photocatalyst

A nanocomposite photocatalyst composed of AlFeO₃ and TiO₂ is prepared, and characterized through X-ray diffraction. Application of the nanocomposite for the photodegradations of eosin dye and methyl orange gives an improved photoactivity compared with TiO₂-only nanomaterials. The optimal concentration of AlFeO₃ in the composite is about 1.0 wt% under UV excitation, and 9.0 wt% under sunlight excitation for the improved photoactivity. Furthermore, this nanocomposite is more active for eosin photodegradation if natural sunlight rather than UV is used. This may be due to the reason that adding AlFeO₃ nanoparticles into TiO₂ matrix can promote the separation of photogener-ated charge carriers, and extend the photoresponse of TiO₂ toward visible region, which results in an increase in the solar energy utilization efficiency.     

Studies on the synthesis of biphenylneolignans. Part 1: Enantioselective synthesis of (S,S)- and (R,R)-2,2′-dimethoxy-4-(3-hydroxy-1-propenyl)-4′-(1,2,3-trihydroxypropyl)diphenyl ether

Two erythro-isomers of 2,2′-dimethoxy-4-(3-hydroxy-1-propenyl)-4′-(1,2,3-trihydroxypropyl)diphenyl ether, (7′S, 8′S)-9 and (7′R, 8′R)-9, were synthesized in seven steps, in which an improved method for the synthesis of the key intermediate 3 was developed. The absolute configuration of the target molecules was also confirmed.     

Sarcophytolides G–L,New Biscembranoids from the Soft Coral Sarcophyton elegans

Six new biscembranoids, namely, sarcophytolides G–L ( 1 – 6 , resp.), together with six known analogs, were isolated from a marine soft coral Sarcophyton elegans. The structures of the new compounds were established on the basis of 1D‐ and 2D‐NMR (COSY, HSQC, HMBC, and NOESY) spectroscopic analysis together with the aid of MS, CD, and IR data. The unusual isobiscembranoid sarcophytolide G ( 1 ) was found for the first time in the genus Sarcophyton.     

Application of Dried Blood Spots and Serum Samples for the Determination of Vitamin D Metabolites in the Group of Healthy Women and with Hashimoto’s Thyroiditis

Chromatographia - The relationship between Hashimoto's thyroiditis and vitamin D concentration was already presented in many studies. The aim of this study was to analyze the differences in the...     

Improved Photovoltaic Performance of MEH-PPV/PCBM Solar Cells via Incorporation of Si Nanocrystals

We have studied the effect of silicon nanocrystals （SiNCs） as a third component on performance of organic bulk heterojunction solar cells composed of poly[2-methoxy,5-（2＇-ethylhexyloxy）-l,4-phenylene vinylene] （MEH- PPV）：[6,6]-phenyI-C61-butyric acid methyl ester （PCBM） blend film. By adding suitable amounts of SiNCs into MEH-PPV：PCBM blend, the device performance such as external quantum efficiency, short circuit current density （Js（）, and power conversion efficiency （PCE） improved. Incorporation of 2.5% SiNCs in the blend led to 13.6% improvement of Jsc, which in turn resulted in 18% improvement of PCE up to 2.28%. The improved performance was mainly due to the improvements both in the charge generation from the interface of MEH-PPV/SiNCs and the charge collection at the cathode.