Enhanced fluorescence emitted by microdroplets containing organic dye emulsions

In this paper, laser beam resonant interaction with pendant microdroplets that are seeded with a laser dye (Rhodamine 6G (Rh6G)) water solution or oily Vitamin A emulsion with Rhodamine 6G solution in water is investigated through fluorescence spectra analysis. The excitation is made with the second harmonic generated beam emitted by a pulsed Nd:YAG laser system at 532 nm. The pendant microdroplets containing emulsion exhibit an enhanced fluorescence signal. This effect can be explained as being due to the scattering of light by the sub-micrometric drops of oily Vitamin A in emulsion and by the spherical geometry of the pendant droplet. The droplet acts as an optical resonator amplifying the fluorescence signal with the possibility of producing lasing effect. Here, we also investigate how Rhodamine 6G concentration, pumping laser beam energies and number of pumping laser pulses influence the fluorescence behavior. The results can be useful in optical imaging, since they can lead to the use of smaller quantities of fluorescent dyes to obtain results with the same quality.     

一种含有二茂铁的rod-coil型两亲性金属有机低聚体的合成与自组装

合成了一种以邻羧基苯甲酰二茂铁为疏水链聚乙二醇单甲醚为亲水链的新型rod-coil两亲性金属有机低聚物,并对其在溶液中的自组装行为进行了研究.研究表明,在不同的起始浓度下,该化合物可自组装形成球形、扭曲的蠕虫状胶束和囊泡,二茂铁和苯环间的π-π相互堆叠是形成扭曲型蠕虫状胶束的主要因素.     

Direct transformation of dinitrogen: synthesis of N-containing organic compounds via N−C bond formation

N-containing organic compounds are of vital importance to lives. Practical synthesis of valuable N-containing organic compounds directly from dinitrogen (N₂), not through ammonia (NH₃), is a holy-grail in chemistry and chemical industry. An essential step for this transformation is the functionalization of the activated N₂ units/ligands to generate N−C bonds. Pioneering works of transition metal-mediated direct conversion of N₂ into organic compounds via N−C bond formation at metal-dinitrogen [N₂-M] complexes have generated diversified coordination modes and laid the foundation of understanding for the N−C bond formation mechanism. This review summarizes those major achievements and is organized by the coordination modes of the [N₂-M] complexes (end-on, side-on, end-on-side-on, etc.) that are involved in the N−C bond formation steps, and each part is arranged in terms of reaction types (N-alkylation, N-acylation, cycloaddition, insertion, etc.) between [N₂-M] complexes and carbon-based substrates. Additionally, earlier works on one-pot synthesis of organic compounds from N₂ via ill-defined intermediates are also briefed. Although almost all of the syntheses of N-containing organic compounds via direct transformation of N₂ so far in the literature are realized in homogeneous stoichiometric thermochemical reaction systems and are discussed here in detail, the sporadically reported syntheses involving photochemical, electrochemical, heterogeneous thermo-catalytic reactions, if any, are also mentioned. This review aims to provide readers with an in-depth understanding of the state-of-the-art and perspectives of future research particularly in direct catalytic and efficient conversion of N₂ into N-containing organic compounds under mild conditions, and to stimulate more research efforts to tackle this long-standing and grand scientific challenge.     

The effect of radioactive radiations upon euglena

An examination has been made of the rate of death of euglena cells when exposed to the alpha particle radiation from radium emanation dissolved in the containing liquid. It was found that the rate of death of the cells was pro. portional to the strength of the dissolved emanation and to the number of live euglena cells present, a conclusion in harmony with the view that death of a cell is caused by a single impact of some sensitive region with an alpha particle. The theory of the case where two impacts of the sensitive region with an alpha particle are necessary to cause death, has been worked out with a generality which allows for a recovery of the cells between the two impacts.It is found that the results of the experiment are inconsistent with such a hypothesis.From the experimental data, it is possible to calculate the size of the sensitive entity which when struck by the alpha particle causes death to the cell. The diameter of this entity comes out about equal to that of the nucleus of the euglena cell.     

测定大蒜活性物质含硫化合物方法定硫法的改进和评价

本实验对改进后的定硫法进行了实验验证。结果表明：（1）硫酸钡实验得到的硫酸钡实验曲线的线性回归公式为：Y=0．0844X-9×10^-5,相关系数R^2=0．9999,表明采用该改进的定硫法定量测定硫酸钡含量是可行的。（2）定量滤纸空白试验表明定量滤纸过滤前后的质量误差非常小,范围在0．5％之内。这说明滤纸在酸性条件下质量几乎不受损失。最后得出改进后的定硫法在测定大蒜活性物质硫化物时的操作方法。