Type 2 intramolecular N-acylnitroso Diels-Alder reaction: scope and application to the synthesis of medium ring lactams

Heteroatom variants of the type 2 intramolecular Diels-Alder reaction provide an efficient method for the preparation of bridged bicyclic heterocycles. The type 2 variant of the intramolecular N-acylnitroso Diels-Alder reaction is an effective method for the synthesis of bridged bicyclic oxazinolactams. Structural studies of the cycloadducts have allowed for quantification of the deformations of the bridgehead functionalities and provided a strategy for the stereoselective synthesis of substituted seven- and eight-membered ring lactams. Diastereoselective cycloadditions followed by cleavage of the oxazine ring afford azepin-2-ones or azocin-2-ones.     

Multilayer assembly and patterning of poly(p-phenylenevinylene)s via covalent coupling reactions

Poly(p-phenylenevinylene)s with amines and pentafluorophenyl esters on side chains were synthesized and assembled on solid substrates by sequential layer-by-layer (LBL) deposition. This approach enables the creation of robust multilayer thin films via in-situ covalent coupling reactions between successive layers. The buildup of the multilayers was followed by UV/vis absorption spectroscopy and ellipsometry. The observed complex assembly behavior suggests that both covalent and hydrogen-bonding interactions are involved in the formation of multilayer films. The organized structure and surface morphology of resultant multilayers were investigated by reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. This covalent LBL method was further applied to generate conjugated polymer micropatterns using microstamped self-assembled monolayers as templates.     

Influence of acid treatments of carbon nanotube precursors on Ni/CNT in the synthesis of carbon nanotubes

The Ni/CNT catalyst was fabricated by directly dipping carbon nanotube precursors refluxed in 4 M of nitric acid into Ni electroless plating bath, and used to synthesize new carbon nanotubes. The experimental results indicate that the duration of acid-treatment of carbon nanotubes precursors exerts a great influence on the catalysis of Ni/CNT in the synthesis of carbon nanotubes and hence the structures of the new carbon nanotubes. When the carbon nanotubes precursors were refluxed for 0.5 h in 4 M of nitric acid, bamboo-shaped carbon nanotubes (BSCNT) or Y junction carbon nanotubes in the carbon products were obtained. As the duration of acid-treatment of carbon nanotubes precursors increased to 6 h, the as-prepared Ni/CNT displayed higher activity, and the carbon nanotube products were high pure without any Y junction structure or any separation layers in hollow.     

Correlation of the gradient diffusion coefficients of human lactoferrin with interparticle interactions validated by photon correlation spectroscopy

The gradient diffusion coefficients of recombinant human lactoferrin, a glycoprotein that is of commercial interest, have been extensively investigated theoretically and experimentally. A theoretical prediction was developed to allow calculation of the thermodynamic coefficient in terms of the electrostatic repulsive forces, London-van der Waals forces, entropic forces and additional interactions of unknown source and determination of the hydrodynamic coefficient by a perturbation theory method. In addition, dilute limit calculations were carried out for both of them. The thermodynamic and hydrodynamic coefficients were incorporated in the generalised Stokes-Einstein equation to calculate the gradient diffusion coefficient. Dynamic light scattering experiments were also conducted under different physiochemical conditions in which the gradient diffusion coefficients and the mean sizes of the macromolecules were measured. It was shown that of the theoretical approaches studied, good quantitative agreement between theory and experiment was found.     

钕诱导番茄产生抗性的时间研究

采用盆栽试验研究了Nd3 在不同诱导时间对番茄叶抗性指标(过氧化物酶(POD)、多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)活性、细胞膜透性、氧自由基(O2-·)产生速率和木质素含量)的影响.结果表明:从第3 d开始,Nd3 诱导提高番茄叶内PAL活性,第3d增幅也最大,达32.30%,维持时间为诱导后第3～5 d;Nd3 诱导后第1～2 d POD活性升高,第1 d增幅最大,维持时间是诱导后第1～2 d;Nd3 诱导后1～3 d,PPO活性升高,第1 d增幅最大,维持时间是诱导后第1～3 d;从诱导后第2 d开始,Nd3 降低细胞膜透性,第3 d时降幅最大,为54.33%,持续时间为诱导后第2～5 d;从第3 d开始,Nd3 诱导降低氧自由基产生速率,第4 d降幅最大,第3 d氧自由基产生速率最低,持续时间为诱导后第3～5 d;从第4 d开始,Nd3 诱导提高木质素含量,5 d时有继续升高的趋势.从不同诱导时间番茄叶PAL活性、细胞膜透性、氧自由基产生速率的变化来看,在Nd3 诱导的第3 d,番茄产生的抗性最强.     

一阶导数差示脉冲极谱法用于甲硝唑的定量研究

本实验运用一阶导数差示脉冲极谱法对甲硝唑及其制剂进行了定量研究。在０．００１ｍｏｌ／Ｌ氯化钾－０．００１ｍｏｌ／Ｌ盐酸－水（１＋０．２＋４８）的底液中，甲硝唑于－０．８００Ｖ（ｖｓ Ａｇ／ＡｇＣｌ）处出现一良好的一阶导数差示脉冲极谱峰，在５０～３００μｇ／ｍＬ范围内，药物浓度与其导数峰幅值呈线关系，检测限为８．０×１０＾－８ｍｏｌ／Ｌ。本法操作简便，快速，灵敏，结果准确。     

1—酰基—4—氯环己烷与取代芳烃的区域与立体选择性反应

从环己烯合成了１－酰基－４－氯环己烷，发现在其在ＡｌＣｌ３催化与苯，氯苯，溴苯等优先生成反式１－芳基－４－酰基环己烷，与联苯反应时选择性较差。     

Mass spectrometry-based chemical mapping and profiling toward molecular understanding of diseases in precision medicine

Precision medicine has been strongly promoted in recent years. It is used in clinical management for classifying diseases at the molecular level and for selecting the most appropriate drugs or treatments to maximize efficacy and minimize adverse effects. In precision medicine, an in-depth molecular understanding of diseases is of great importance. Therefore, in the last few years, much attention has been given to translating data generated at the molecular level into clinically relevant information. However, current developments in this field lack orderly implementation. For example, high-quality chemical research is not well integrated into clinical practice, especially in the early phase, leading to a lack of understanding in the clinic of the chemistry underlying diseases. In recent years, mass spectrometry (MS) has enabled significant innovations and advances in chemical research. As reported, this technique has shown promise in chemical mapping and profiling for answering “what”, “where”, “how many” and “whose” chemicals underlie the clinical phenotypes, which are assessed by biochemical profiling, MS imaging, molecular targeting and probing, biomarker grading disease classification, etc. These features can potentially enhance the precision of disease diagnosis, monitoring and treatment and thus further transform medicine. For instance, comprehensive MS-based biochemical profiling of ovarian tumors was performed, and the results revealed a number of molecular insights into the pathways and processes that drive ovarian cancer biology and the ways that these pathways are altered in correspondence with clinical phenotypes. Another study demonstrated that quantitative biomarker mapping can be predictive of responses to immunotherapy and of survival in the supposedly homogeneous group of breast cancer patients, allowing for stratification of patients. In this context, our article attempts to provide an overview of MS-based chemical mapping and profiling, and a perspective on their clinical utility to improve the molecular understanding of diseases for advancing precision medicine.

An overview of MS-based chemical mapping and profiling, indicating its contributions to the molecular understanding of diseases in precision medicine by answering "what", "where", "how many" and "whose” chemicals underlying clinical phenotypes.     

Flow-injection chemiluminescence determination of fluoroquinolones by enhancement of weak chemiluminescence from peroxynitrous acid

A flow-injection chemiluminescence (CL) method is described for the determination of fluoroquinolones including ciprofloxacin, norfloxacin and ofloxacin. The method is based on the enhancement by these compounds of the weak CL from peroxynitrous acid. The linear ranges are 1.0×10⁻⁷ to 1.0×10⁻⁵ mol l⁻¹ for ciprofloxacin and norfloxacin, and 3.0×10⁻⁷ to 3.0×10⁻⁵ mol l⁻¹ for ofloxacin, respectively. The detection limits (S/N=3) are 4.5×10⁻⁸ mol l⁻¹ ciprofloxacin, 5.9×10⁻⁸ mol l⁻¹ norfloxacin and 1.1×10⁻⁷ mol l⁻¹ ofloxacin, respectively. The proposed method was applied to the determination of fluoroquinolones in pharmaceutical preparations.