Electrically forced coaxial nanojets for one-step hollow nanofiber design

The outer liquid of a two-liquid coaxial electrified jet is gelled before the onset of natural instabilities to yield hollow nanofibers. By using sol-gel chemistry, innocuous solvents such as glycerol and olive oil, and electrohydrodynamics, it is possible to make such structures in a rather straightforward manner.     

Steady cone-jet electrosprays in liquid insulator baths

This study shows that conducting liquids can be electrosprayed in steady cone-jet mode inside liquid insulator baths. Experimental results show that the current emitted from the meniscus fits well the scaling laws given in the literature for electrosprays in air at atmospheric pressure or vacuum. The technique may be of interest in obtaining fine liquid-liquid emulsions of uniformly sized droplets in the nanometric range.     

A new efficient synthesis of 3‐(hydroxymethyl)‐4H‐chromen‐4‐ones

An efficient and versatile synthesis of variously substituted 3‐(hydroxymethyl)‐4H‐chromen‐4‐ones is reported. The compounds are prepared by hydroxymethylation of the precursor 2‐hydroxy‐4‐chromanones followed by acid dehydration.     

Simple and double emulsions via coaxial jet electrosprays

We report for the first time the generation of electrified coaxial jets of micrometric diameter in liquid media. Scaling laws to predict the inner and outer diameter of the coaxial jet are given. We show some experiments illustrating the formation process of the coaxial jet, and demonstrate how this process can be used to yield either o/w (oil in water) or o/w/o (oil/water/oil) emulsions of micrometric size. Some interesting analogies with other hydrodynamic focusing processes are also pointed out.     

A method for making inorganic and hybrid (organic/inorganic) fibers and vesicles with diameters in the submicrometer and micrometer range via sol-gel chemistry and electrically forced liquid jets

Electrically driven liquid jets are combined with sol-gel methods to design vesicles and fibers made from inorganic oxides and hybrid materials with diameters in the micrometer and submicrometer range. The proposed materials synthesis method benefits greatly from the maturity of sol-gel chemistry and the generalities of a structure-directing phenomenon that is physical in nature.     

An experimental study of the electrospraying of water in air at atmospheric pressure

Water solutions with electrical conductivities ranging from that of the deionized water up to 2 S/m have been electrosprayed in air through narrow silica tubes. Results show unambiguously that steady cone jets of water in air without the assistance of glow discharge can be formed for the range of electrical conductivities we have explored. The absence of corona discharge has been proven not only for the good agreement between the experimental results and the scaling laws given in the cone-jet literature but also for the independence of the spray current on the atmosphere (air or CO(2)) in which water was being electrosprayed. Other regimes such as the electric dripping and the assisted glow discharge cone-jet mode that appear in the electrospraying of water in air at room temperature have also been investigated.     

Electromagnetic scattering by a homogeneous chiral obstacle in a chiral environment

Time-harmonic electromagnetic waves are scattered by a homogeneouschiral obstacle embedded in a chiral environment. The correspondingtransmission problem is reduced, via Bohren's decomposition,to an integral equation over the interface between the obstacleand the surrounding medium. This integral equation is shownto be uniquely solvable except for a discrete set of electromagneticparameters of the obstacle.     

通过毛细流动制备微纳粒子

回顾了若干能够将流体交界面拉伸至微米及更小尺度的毛细流动. 这些流动类型已经成为制备单分散性微-纳粒子技术的基础. 这些技术正引起人们的关注, 它们既能制造简单结构的粒子, 也能制造核-壳结构的粒子(微纳胶囊、同轴纳米纤维以及中空纳米纤维), 而且能够精确地控制粒子的平均尺寸. 本文还评述了流动的基本物理以及控制这些毛细流动的无量纲参数. 此外, 文中还给出一些实例, 介绍利用几种装置制备的不同类型粒子.