水溶性荧光CdSe量子点的合成及其在指纹显现中的应用

Water-soluble fluorescent CdSe quantum dots(QDs) were synthesized by using Se、Na₂SO₃ and CdCl₂ as precursors and mercaptoacetic acid(TGA) as modifier. The effects of refluxing time and initial pH values of the reaction on the particle size and fluorescence intensity of CdSe QDs were studied. The XRD、HRTEM and fluorescent spectroscopy were employed to characterize these samples. It is found that CdSe QDs with crystalline size of 2～3 nm are homogeneously distributed in the organic matrix. The maximum fluorescence absorption and emission peak of CdSe QDs solution are at 450 nm and 562 nm, respectively. The fingerprint details on the surface of smooth objects were clearly developed with CdSe QDs solution under irradiation of UV lights.     

A versatile synthesis of meyers' bicyclic lactams from furans: singlet-oxygen-initiated reaction cascade

All in one: Meyers' bicyclic lactams were synthesized in high yield from furans using a new and powerful method that involves a one-pot singlet-oxygen-initiated reaction cascade (see scheme; TFA=trifluoroacetic acid). This method has broad synthetic potential because of the ease of access to a wide range of furans with a variety of substituents.     

Label‐Free Electrochemical Imaging of Latent Fingerprints on Metal Surfaces

A label‐free electrochemical method based on scanning electrochemical microscopy (SECM) has been developed to image latent fingerprints with high resolution on five kinds of metal surfaces (platinum, gold, silver, copper and stainless steel), as it could measure the minor conductivity differences of the substrate surface and avoid the interference of the background‐color. The images of sebaceous fingerprints on clean metals were revealed by SECM with ferrocene methanol acting as a redox mediator to detect the topology of the fingerprint deposits in constant‐height feedback mode. Inhibition of electrochemical processes on areas of the surface masked by the insulating fingerprint residues generated a negative image of the fingerprint.     

APPLICATION OF HMBC AND HMQC-TOCSY NMR METHODS TO ASSIGN THE STRUCTURES OF BICYCLIC-PEPTIDE MIMETICS

Abstract

The structures of representative bicyclic peptides are confirmed through the NMR methods of HMBC and HMQC-TOCSY. Complete assignment of proton and carbon resonances is afforded by these two-dimensional NMR methods. HMQC-TOCSY is especially useful for assigning spectra in molecules having extensive proton spin systems and in establishing connectivities between protonated carbons. Long-range proton-carbon connectivities obtained by HMBC confirm structure in molecules containing heteroatoms or non-protonated carbons that interrupt proton spin systems.     

Establishing the minimal index in a parametric family of bicyclic biquadratic fields

Let c ≥ 3 be a positive integer such that c, 4c + 1, c − 1 are square-free integers relatively prime in pairs. In this paper we find the minimal index and determine all elements with minimal index in the bicyclic biquadratic field K = ℚ(√(4c + 1)c, √(c − 1)c). The author was supported by the Ministry of Science, Education and Sports, Republic of Croatia, grant 037-0372781-2821.     

化学合成荧光量子点在指纹显现中的应用

简要阐述了量子点的光学特性、制备方法及其在指纹显现中的应用。重点介绍了Ⅱ~Ⅵ族的CdS基、CdTe基、CdSe基、ZnSe基量子点和Ⅲ~Ⅴ族的InP量子点的化学合成、修饰及其在指纹显现中的研究进展,最后介绍了第Ⅳ族C、Si量子点的研究现状,并对其在指纹显现中的潜在应用作了展望。     

丹皮药材的高效液相色谱-质谱/质谱研究

采用高效液相色谱．质谱／质谱建立了丹皮药材的指纹图谱方法。丹皮药材中的主要成分得到较好分离,指纹峰重现性好,通过多维联用技术获得各指纹峰的保留时间、分子量及结构信息,推测出15个指纹峰的可能组成。结果表明：所建立的丹皮指纹图谱信息量丰富,对丹皮药材的化学表征及质量评价有重要的参考价值。     

内燃机油高效液相指纹图谱的建立

建立了内燃机油指纹图谱的高效液相色谱(HPLC)分析方法。采用反相C18柱,以乙腈-水为流动相梯度洗脱,检测波长280 nm,柱温30℃,进样体积10μL进行试验。考察结果表明,指纹图谱中各共有色谱峰的相对保留时间α和相对峰面积Sr的相对标准偏差(RSD)均小于2.4%,满足小于3%的指纹图谱研究技术要求。通过共有特征峰分析以及色谱峰重叠率、相似度的计算,可进一步鉴别和评价内燃机油的质量。该法与传统的内燃机油品质评价方法相比,节约了试验成本和时间,为内燃机油的快速鉴别和质量控制开拓了新领域。     

高效液相色谱指纹图谱在中药芦根上的应用

利用现代分离分析技术如高效液相色谱(HPLC)与气相色谱(GC),能够获得中草药的色谱指纹图谱。本实验报道了高效液相指纹图谱应用于快速检测中草药提取物以及应用于研究、开发与生产中的质量控制体系中,利用HPLC建立芦根的色谱指纹图谱。实验条件为反相C18柱,流速为1．0mL／min,紫外检测器(λ=230nm)。通过分析比较色谱指纹图谱中的相对保留值α以及相对面积St对不同产地的芦根进行对比研究。这种基于HPLC的分析策略为中草药的精确鉴定和质量控制提供了有效的信息,并为HPLC在复杂组分样品中的应用开拓了新的领域。