番红花红T与表面活性剂的作用及其在标记DNA中的应用

对阳离子染料番红花红Ｔ（ＳＴ）在阴离子表面活性剂存在时的溶液状态的吸收光谱和荧光光谱进行了研究。结果表明，低浓度阴离子表面活性剂与ＳＴ形成缔合物，导致ＳＴ的吸收与荧光强度降低；增大表面活性剂的浓度，其分子胶束前预聚集促使染料形成非荧光二聚体，导致荧光急剧猝灭，吸收光谱出现新的特征吸收峰；当表面活性剂浓度大于临界胶束浓度（ＣＭＣ）时，染料二聚体离解，ＳＴ单体增溶于胶团中形成新的高量子产率荧光体。本文     

On the hyperfine structure in the configuration 5f 3 6d7s 2 of neutral uranium

A Laser Induced Fluorescence experiment in an atomic beam has yielded experimental values of hyperfine structure (hfs) constants A and B for 28 low odd levels and 22 even levels, with an accuracy around 10^–5 cm^–1 for A and 10^–3 cm^–1 for B. A Condon Slater Racah parametric interpretation of the hfs data concerning 22 of these levels, on the basis of the configuration 5f ³ 6d 7s ², has provided values of monoelectronic parametersa _5f ⁰¹ ,a _5f ¹² ,a _6d ⁰¹ ,b _5f ⁰² ,b _6d ⁰² ,b _6d ¹³ . A least square fit calculation has been compared to the values deduced from Dirac-Fock monoelectronic radial integrals. The fit represents 18 A (16 B) values ranging from –0.42 to –2.96 mK (from –41 to 156 mK) with discrepancies less than 0.2 mK (8 mK).     

A Ten Years Monitoring of Chlorofluorocarbons at the Antarctica: Results and Perspectives

Abstract

Chlorofluorocarbons are man-made long lasting atmospheric pollutants of great environmental concern, responsible for important global change phenomena. Recently, they were replaced by hydrogenated halocarbons that, even if less persistent, do not lack in environmental impact. Atmospheric concentrations of these compounds were measured in Antarctica by gas chromatography. The extremely low atmospheric mixing ratios of these compounds require a pre-concentration step of the air sample on suitable adsorbent in order to meet the sensitivity of the analytical method Results obtained analyzing air samples collected in Antarctica since 1988 for the determination of CFC-12 and CFC-11 are reported, together with data concerning the less abundant species.     

Effect of deuteron density distribution on the deduction of screening potential from the D(d,p)T reaction in Be metals

The D(d,p)T reaction in Be metal environments has been measured to investigate the electron screening effect in metals in an energy region of from 5.5 keV to 10 keV in a center of mass system(CMS)at a temperature of 121 K.The depth distribution of deuteron density in Be metals has an impact on the observed reaction yields.A model of deuteron density distribution in metal has been proposed to obtain the original yields.A screening energy of(116±46)eV has been obtained with the assumed deuteron density distribution model.     

RNA Ligation for Mono and Dually Labeled RNAs

Labeled RNAs are invaluable probes for investigation of RNA function and localization. However, mRNA labeling remains challenging. Here, we developed an improved method for 3′-end labeling of in vitro transcribed RNAs. We synthesized novel adenosine 3′,5′-bisphosphate analogues modified at the N6 or C2 position of adenosine with an azide-containing linker, fluorescent label, or biotin and assessed these constructs as substrates for RNA labeling directly by T4 ligase or via postenzymatic strain-promoted alkyne-azide cycloaddition (SPAAC). All analogues were substrates for T4 RNA ligase. Analogues containing bulky fluorescent labels or biotin showed better overall labeling yields than postenzymatic SPAAC. We successfully labeled uncapped RNAs, NAD-capped RNAs, and 5′-fluorescently labeled m⁷Gp₃A_m-capped mRNAs. The obtained highly homogenous dually labeled mRNA was translationally active and enabled fluorescence-based monitoring of decapping. This method will facilitate the use of various functionalized mRNA-based probes.     

明胶改性聚醚醚酮微载体的制备、表征及性能

微载体因其具有较高的表面积/体积比等优点可以大大提高哺乳动物细胞培养效率,被广泛应用于生物制药和组织工程等领域。 但微载体多为一次性使用,不耐高温,且主要依赖进口,价格昂贵,因而限制了其国内的应用和推广。 聚醚醚酮(PEEK)材料具有良好的生物相容性、化学稳定性及耐高温等特性,是一种优异的微载体材料,但存在熔点高,加工方法单一和生物惰性等缺陷。 本文以浓硫酸为溶剂,乙醇溶液为萃取剂,采用气流辅助滴注/相分离法,将PEEK制备成448 μm左右,尺寸均匀的微球;经氨丙基三乙氧基硅烷(APTES)处理,获得表面氨基化修饰的PEEK微球(PEEK-N);进一步,以N,N'-羰基二咪唑(CDI)为活性中间体,将明胶分子接枝到PEEK-N微球表面,获得表面明胶修饰的PEEK微载体(PEEK-G)。 对材料的物理化学性质、表面接枝量进行表征;并通过体外细胞实验评估其细胞毒性、细胞粘附效率和细胞增殖能力。 结果显示,通过该方法制备成功了3种不同明胶接枝含量的PEEK细胞微载体(PEEK-G1,PEEK-G2,PEEK-G3),其中明胶含量较高的PEEK-G3毒性最低,细胞粘附和增殖效果最理想。     

Solid‐state drawing of β‐nucleated polypropylene: Effect of additives on drawability and mechanical properties

Isotactic polypropylene (i‐PP) can crystallize in different crystal modifications. In this article, the effect of sepiolite (one‐dimensional) and carbon black (three‐dimensional) fillers on the solid‐state drawability of i‐PP is discussed. The cross‐hatched structure of thermodynamically most stable α‐crystal phase in i‐PP does not allow for perfect chain alignment during solid‐state drawing. The β‐phase i‐PP, obtained by addition of specific nucleating agents, crystallizes in a non‐cross‐hatched spherulitic structure and allows more easy drawing. Depending on the filler type, β–α transformation takes place at different draw ratios, as was observed by in situ wide‐angle X‐ray diffraction measurements. It was observed that β‐nucleated i‐PP has a lower yield stress and can be drawn further than i‐PP crystallized in the α‐crystal phase. If added in the right amount, both carbon black and sepiolite have a reinforcing effect on PP tapes. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1071–1082