The refined theory of the electroviscous lift forces is presented for the case when the separation distance between the particle and the wall is larger than the double-layer thickness. The theory is based on the lubrication approximation for motion of a long cylinder near a solid wall in creeping flow. The approximate analytical formula for the lift force valid for Pe相似文献
Histone modifications are important epigenetic mechanisms involved in eukaryotic gene regulation. Chromatin immunoprecipitation (ChIP) assay serves as the primary technique to characterize the genomic locations associated with histone modifications. However, traditional tube-based ChIP assays rely on large numbers of cells as well as laborious and time-consuming procedures. Here we demonstrate a novel microfluidics-based native ChIP assay which dramatically reduces the required cell number and the assay time by conducting cell collection, lysis, chromatin fragmentation, immunoprecipitation, and washing on a microchip. Coupled with real-time PCR, our assay permits the analysis of histone modifications from as few as ~50 cells within 8.5 h. We envision that our method will provide a new approach for the analysis of epigenetic regulations and protein-DNA interactions in general, based on scarce cell samples such as those derived from animals and patients. 相似文献
It has long been known that arenesulfenyl halides will add to olefins to yield β-halosulfides1. Arene-sulfonyl halides have been shown to react with alkenes2 polyenes3, alkynes4 and allenes5. Although sulfinyl halides have been synthesized for some time6 there appears to be but one brief mention of their reaction with olefins7. In view of the recent increased interest in sulfoxides we decided to reinvestigate this reaction. 相似文献
Currently, all assays measuring acetylcholinesterase (AChE) activity following a suspected nerve agent exposure leverage methodologies that fail to identify the agent. This limits the overall effectiveness and ability to administer proper countermeasures. As such, there is an urgent need to identify novel, rapid, and more comprehensive approaches to establish AChE activity, including identification of the toxicant. Paper spray mass spectrometry was used to monitor the activity of acetylcholinesterase, both in-solution and on modified hydrophobic paper surface. Hydrophobic paper surfaces were prepared using vaporized trichloro(3,3,3-trifluoropropyl)silane. In both approaches, mixtures of diluted human whole blood with and without VX were mixed with a non-endogenous AChE specific substrate, 1,1-dimethyl-4-acetylthiomethylpiperidinium (MATP+). Formation of the cleaved MATP+ product was monitored over time and compared to MATP+ to determine relative AChE activity. This on-substrate assay was effective at determining AChE activity and identifying the toxicant; however, determination of AChE activity in-solution proceeded at a slower rate. The on-substrate assay serves as a pioneering example of an enzymatic reaction occurring on the surface of a paper spray ionization ticket. This work broadens the range of applications relating to paper spray ionization-based clinical diagnostic assays.
