Chemistry in nanochannel confinement

This review addresses the questions of whether it makes sense to use lithographically defined nanochannels for chemistry in liquids, and what it is possible to learn from experiments on that topic. The behavior of liquids in different classes of pores (categorized according to their size) is reviewed, with a focus on chemical reactions and protein dynamics. A number of interesting phenomena are discussed for nanochannels with feature sizes that are manufacturable with modern photolithography-based fabrication technology. The use of spectroscopic methods to investigate chemistry in nanochannels, where both spectroscopic method and nanochannels are integrated into a single device, will be evaluated.     

State of the art of shear driven chromatography. Advantages and limitations

The present paper reports on the experimental difficulties encountered when trying to realize the full potential of shear-driven chromatography in nanochannels. While it theoretically offers the possibility to yield over 10,000 plates per centimetre in a few seconds, the practical realization of this potential requires a detector miniaturisation that is carried to the extreme combined with very high sampling rates. In the present study, a charge coupled device camera and a photomultiplier tube combined with pinhole were tested as detector. Despite the fact that the photomultiplier tube could offer a higher sampling rate and a better sensitivity, the charge coupled device turned out to be better suited for the current set-up because of inevitable problems with the stray-light transported through the glass channel wall. The chemistry of the separation surface was additionally studied getting more homogenous coating, thus higher separation efficiency. Having also carried out a number of mechanical improvements, it is now possible to measure separations at a distance of 8mm downstream from the injection point. This is four times further downstream than ever before while realizing a four components mixture separation in less than 1.5s, with a plate generation velocity of about 2000-7000 plates per second depending on the sample.     

Oxidative Conversion of Hexane to Olefins-Influence of Plasma and Catalyst on Reaction Pathways

An integrated plasma-Li/MgO system is efficient for the oxidative conversion of hexane. In comparison to the Li/MgO catalytic system, it brings considerable improvements in the yields of light olefins (C₂⁼–C₅⁼) at relatively low temperatures indicating synergy from combination of plasma and catalyst. The study on the influence of temperature on the performance of the integrated plasma-Li/MgO system shows dominancy of plasma chemistry at the lower temperature (500°C), while contribution from the catalyst both in hexane activation and in enhancing olefin formation becomes significant at the higher temperature (600°C). At 500°C significant amount of acetylene formation is observed. This is minimized at 600°C at oxygen depleting conditions.     

On the pathway of photoexcited electrons: probing photon-to-electron and photon-to-phonon conversions in silicon by ATR-IR

Photoexcitation and charge carrier thermalization inside semiconductor photocatalysts are two important steps in solar fuel production. Here, photoexcitation and charge carrier thermalization in a silicon wafer are for the first time probed by a novel, yet simple and user-friendly Attenuated Total Reflectance Infrared spectroscopy (ATR-IR) system.     

Separations using a porous-shell pillar array column on a capillary LC instrument (J. Sep. Science 35'16)

DOI: 10.1002/jssc.201200279 A 9 cm silicon long pillar array containing 5 μm diameter silicon pillars cladded with a meso-porous silica layer with a thickness of 300 nm was directly interfaced to a capillary LC instrument, yielding protein digest peak capacities of up to 150.