Aerobic oxidation of benzyl alcohols through biosynthesized palladium nanoparticles mediated by Oak fruit bark extract as an efficient heterogeneous nanocatalyst

In this study, green synthesis of Pd nanoparticles (NPs) is outlined through application of Oak fruit bark extract as a reducing, capping and stabilizing agent. The characteristics and properties of the biosynthesized Pd NPs were revealed by FESEM, EDX, XRD, TEM, UV–Vis, and FT-IR spectroscopies. So that, UV–Vis spectroscopy of the Pd colloidal solution confirmed reduction of Pd ions, and XRD and TEM analysis identified fcc unit cell structure forming 5–7 nm spherical Pd NPs. Furthermore, catalytic activity of the prepared catalyst was investigated through aerobic oxidation of alcohols, as model reactions. Catalytic evaluations demonstrated achievement of good yields from primary and secondary benzyl alcohols. In general, the devised synthesis method is advantageous from several perspectives. For example, the synthesized catalysts give high product yields and are efficient, they eliminate the need for surfactant, chemical reductants, ligand and organic solvents, the approach is economically inexpensive, it results in cleaner reaction profiles, application of the simply prepared heterogeneous catalyst is convenient, and the catalyst is recoverable and reusable for at least six times without any significant loss of its catalytic activity.     

How stereochemistry influences the taste of wine: Isolation,characterization and sensory evaluation of lyoniresinol stereoisomers

Wine expresses its beauty by sending a sensory message to the taster through molecules coming from grapes, yeast metabolism or oak wood. Among the compounds released during barrel aging, lyoniresinol has been recently reported as a relevant contributor to wine bitterness. As this lignan contains three stereogenic carbons, this work aimed at investigating the influence of stereochemistry on wine taste by combining analytical and sensorial techniques. First, an oak wood extract was screened by Liquid Chromatography–High Resolution Mass Spectrometry to target isomers separable in a symmetric environment and a diastereoisomer called epi-lyoniresinol was isolated for the first time. Then, an original racemic resolution based on natural xylose-derivatives was carried out to obtain lyoniresinol enantiomers. Chiroptical spectroscopic measurements associated with theoretical calculations allowed the unambiguous determination of their absolute configuration. The taste properties of all these stereoisomers revealed that only one lyoniresinol enantiomer is strongly bitter whereas the other one is tasteless and the diastereoisomer is slightly sweet. The presence of these three compounds was established in an oaked Bordeaux wine by chiral and non-chiral chromatography, suggesting the significant influence of stereochemistry on wine taste.     

An immunoassay based on lab-on-a-chip for simultaneous and sensitive detection of clenbuterol and ractopamine

Both clenbuterol (CLB) and ractopamine (RAC) are β-adrenergic agonists. After long-term excessive intake, there will be adverse reactions such as headache, chest tightness, limb numbness, and serious life-threatening. Simultaneous detection of CLB and RAC in related samples is of great importance for human health. In this work, we outline a microfluidics-based indirect competitive immunoassay (MICI) system that can sensitively detect residual CLB and RAC in pork, swine blood and swine urine. The rapid detection of multiple samples can be achieved in one chip, which greatly improves the detection efficiency. This method has good stability and reproducibility and the microfluidic chips are easy to manufacture. The linear ranges for CLB and RAC detection by MICI are 0.1–2.5 ng/mL and 0.1–5 ng/mL, and the limits of detection (LODs) are 0.094 ng/mL and 0.091 ng/mL, respectively. This straightforward and portable immunoassay system provides a good platform for rapid detection of harmful substances in food samples.     

Catalytic pyrolysis of oak via pyroprobe and bench scale, packed bed pyrolysis reactors

The pyrolytic conversion of oak sawdust at 500 °C in flowing He over eight proprietary catalysts is described and compared to the control bed material, quartz sand. The reactions were conducted and compared in two reactors, an analytical, μg-scale pyroprobe reactor and a bench, g-scale packed bed reactor. The catalysts examined were modified acid catalysts, dealuminated-zeolite Y, β-zeolite, a naturally occurring metal hydroxide containing mineral, mordenite, and a mesoporous aluminosilicate molecular sieve. The packed bed reactor allowed the collection of three bulk product fractions, char, liquid, and gas, all of which could not be obtained from the μg-scale pyroprobe reactions. The catalysts effect on the mass balance of the bulk fractions tended toward more chars and less liquid compared to the sand control. The catalysts’ effects on the liquid products obtained in both reactors shifted away from acetic acid, furfural and higher molecular weight phenolics obtained with sand to lower molecular weight aromatics. This halved the total acid number of the liquid fraction and raised the pH by up to 1.4 units. The modified catalysts’ effects on the gas products from both reactors did not follow a specific trend. Instead, specific catalysts were able to enrich specific gas species up to a factor of 15 while suppressing the formation of others compared to the sand control. Two catalysts, β-zeolite and a naturally occurring metal hydroxide containing mineral, were regenerated and recycled up to five times with no loss of activity.     

微流控芯片设计方法研究进展

本文综述了微流控芯片设计方法的研究进展,归纳和总结了目前主要的设计方法,包括数值模拟法和基于宏模型的设计方法。最后介绍了宏-微模型设计方法,通过建立宏-微接口,实现了数值模拟和宏模型的灵巧桥接,有助于改善微流控芯片设计方法的兼容性和自适应性。     

Catalytic Square-Wave Voltammetric Determination of Acrylamide in Potato Chips

Abstract

Square-wave voltammetry is a fast technique used for determination of trace amounts of acrylamide. When cobalt(II) ions were added to the acrylamide solution, a catalytic peak at about ?1.35 V vs. Ag/AgCl was observed, which was proportional to acrylamide concentration. The calibration curve showed good linearity in the range of 200–800 ng mL^?1 of acrylamide with a regression coefficient of 0.9989. The limit of detection of the method was 3.52 ng mL^?1, and the relative standard deviations for concentrations of 300 ng mL^?1 and 700 ng mL^?1 were 99.8% × 10^?2 and 79.7% × 10^?2, respectively.     

医用微流控芯片研究进展

近年来,随着社会经济的飞速发展,新型科学技术层出不穷,微流控芯片因具有试剂消耗量少、能耗低、反应速度快、高通量化、液体自驱等独特优势,已经发展成为集生化、医学、电子、材料及其交叉学科的研究热点.微流控技术(microfluidics)是在微电机加工系统(MEMS)技术基础上发展而来的,是在微米级微管中精确操纵微量流体的...     

Microwave coherent manipulation of cold atoms in optically induced fictitious magnetic traps on an atom chip

We propose a novel on-chip platform for controlling and manipulating cold atoms precisely and coherently. The scheme is achieved by producing optically induced fictitious magnetic traps(OFMTs) with 790 nm(for ~(87)Rb) circularly polarized laser beams and state-dependent potentials simultaneously for two internal atomic states with microwave coplanar waveguides. We carry out numerical calculations and simulations for controlled collisional interactions between OFMTs and addressable single atoms' manipulation on our designed hybrid atom chips. The results show that our proposed platform is feasible and flexible, which has wide applications including collisional dynamics investigation, entanglement generation,and scalable quantum gates implementation.     

微型化在化学科学发展中的战略地位

本文论述了微型化在化学科学未来发展中的战略作用和潜力,强调了微流控技术在生物和药物化学分析、及大规模平行化学反应等领域发展中的重要性,并预测微型化将极大改善化学系统的效率、成本、安全性和灵活性等。     

超滤法处理改善小鼠单抗的固定化效果

商品化小鼠单抗试剂中普遍添加了高浓度的保护蛋白,如牛血清白蛋白(BSA),这给抗体的固定化带来了严重的干扰。本研究基于超滤技术发展了一种超微量抗体试剂(用量为10μL,约含2μg抗体、100μgBSA)预处理方法,能有效去除商品化抗体试剂中的高浓度BSA,使微珠表面固定化小鼠单抗的数量显著提高,并在蛋白质检测中得到了较好的结果,为缓解抗体产品供应现状对蛋白质芯片研究工作的制约提供了一条简单实用的途径。