The mechanism of Sandmeyer's cyclization reaction by electrospray ionization mass spectrometry

Using electrospray ionization (tandem) mass spectrometry (ESI-MS(/MS)) spectrometric experiments, the Sandmeyer reaction was monitored on-line, and key intermediates were intercepted and characterized for the first time. The mechanistic information provided by on-line ESI-MS(/MS) is in accordance with Sandmeyer's proposal, and was made possible by coupling a microreactor on-line to the ESI ion source, which allowed reactions to be screened from 0.7-2.0 s, identifying and characterizing all intermediates that were formed and consumed during the reaction.     

Tuning Cellular Biological Functions Through the Controlled Release of NO from a Porous Ti‐MOF

Materials for the controlled release of nitric oxide (NO) are of interest for therapeutic applications. However, to date, many suffer from toxicity and stability issues, as well as poor performance. Herein, we propose a new NO adsorption/release mechanism through the formation of nitrites on the skeleton of a titanium‐based metal–organic framework (MOF) that we named MIP‐177, featuring a suitable set of properties for such an application: (i) high NO storage capacity (3 μmol mg^?1_solid), (ii) excellent biocompatibility at therapeutic relevant concentrations (no cytotoxicity at 90 μg mL^?1 for wound healing) due to its high stability in biological media (<9 % degradation in 72 hours) and (iii) slow NO release in biological media (≈2 hours for 90 % release). The prospective application of MIP‐177 is demonstrated through NO‐driven control of mitochondrial respiration in cells and stimulation of cell migration, paving the way for the design of new NO delivery systems for wound healing therapy.     

微米铜丝的低温力学性能测试

针对纤维材料变温环境力学性能测试的需要,在华中科技大学研制的纤维材料试验机的基础上引入了温控装置,从而实现纤维材料在高低温环境下的力学性能测试。采用该装置对不同直径微米铜丝在不同温度、不同拉伸速率条件下的力学性能开展实验研究,测试结果表明弹性模量和抗拉强度随温度的降低而线性增加,屈服强度的变化不太明显。另外,低温环境下微米铜丝的力学性能表现出与其直径相关的尺度效应,而这一现象在常温下一直没有观测到。最后,还研究了拉伸速率对微米铜丝的力学性能影响,结果表明,在现有装置的许用范围之内,拉伸速率对其力学性能的影响不大。     

From superhydrophobic‐ to superhydrophilic‐patterned poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) architectures as a novel platform for biotechnological applications

The manufacture of three‐dimensional patterned electroactive poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) microstructures with tailored architecture, morphology, and wettability is presented. The patterned microstructures are fabricated using a simple, effective, low cost, and reproducible technique based on microfluidic technology. These novel structures can represent innovative platforms for advanced strategies in a wide range of biotechnological applications, including tissue engineering, drug delivery, microfluidic, and sensors and actuators devices. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1802–1810     

Analytical applications of membrane extraction in chromatography and electrophoresis

An overview of the analytical applications of membrane-based systems for sample enrichment in chromatography and capillary electrophoresis is presented. A brief introduction to the different types of membranes and the main forces related to the transport through them is also given.     

Comparative study of epithelial and fibroblastic cell lines as an alternative cytotoxicity test to the Draize method

Several methods are being used with considerable advantage as alternatives to the Draize test, although some technical difficulties still persist. This work compared the sensitivity of HeLa and NCTC L 929 cells to evaluate the cytotoxicity of shampoos used by adults and children (undiluted and diluted to 25, 5, 1, and 0.1%), and eye drops and their containers and surfactants (diluted to 30, 10, 1, and 0.1%). Nondiluted adult shampoos and their 25 and 5% dilutions were cytotoxic for both cell lines. When diluted to 1%, only one of the shampoos was noncytotoxic, whereas among those diluted to 0.1%, only one was cytotoxic. Children's shampoos were cytotoxic when not diluted or diluted to 25%. From those diluted to 5%, only one was noncytotoxic for both cell lines. The cytotoxic tests showed that the eye drops and their containers were noncytotoxic. Surfactants were cytotoxic when diluted to 30 and 10% and noncytotoxic when diluted to 1 and 0.1%. An excellent correlation (r = 0.95) was demonstrated between the sensitivity of the HeLa and NCTC L929 cells in the evaluation of cytotoxicity reactions.     

Synthesis of New Xanthones,I

Condensation of salicylic acid and C-methylphloroglucinol gave the already known 1,3-dihydroxy-2-methylxanthone ( 1 ) along with two new compounds: 1,3-dihydroxy-4-methylxanthone ( 2 ) and a second one tentatively presented as being 1,3-dihydroxy-2-methyl-4-(2-hydroxybenzoyl)xanthone ( 3 ). The UV., IR., NMR, and mass spectra for the two first compounds are reported and their structures discussed on the basis of δ-values for H(2), H(4), CH₃(4) and CH₃(2). The UV. and IR. spectra for the third compound are reported too.     

Magnetic nanoscale aggregates of cobalt and nickel in MgO single crystals

The magnetic properties of Co and Ni nanosized aggregates formed after implantation of nickel and cobalt ions in magnesium oxide single crystals were investigated. The influence of the implantation energy and annealing treatments was characterized. The particle size distribution was determined from the combined analysis of the magnetic moment dependence on both magnetic field and temperature, and used to determine the magnetic anisotropy constant of the aggregates. The results for nickel aggregates indicate the presence of an antiferromagnetic layer after the annealing treatments.     

Strain-driven morphology of Si1-xGex islands grown on Si(100)

A study has been carried out on the morphology and structure of three-dimensional (3D) SiGe islands grown by molecular beam epitaxy (MBE) on Si(100) substrates. Samples of Si1-xGex alloys have been prepared to investigate the effects either of the alloy composition or of the growth temperature. Atomic force microscopy (AFM) evidenced the growth of 3D islands and transmission electron microscopy (TEM) demonstrated wetting layer growth on Si(100), independently on the deposition conditions. Energy dispersive spectroscopy (EDS) micro-analyses carried out on cross-sections of large Si1-xGex islands with defects allowed a measurement of the Ge distribution in the islands. To the best of our knowledge, these have been the first experimental evidences of a composition change inside SiGe islands. The interpretation of the experimental results has been done in terms of strain-enhanced diffusion mechanisms both of the growing species (Si and Ge) and of small islands.