نتایج جستجو برای: molecular ion

تعداد نتایج: 820311  

2001
Robert H. Austin Jonas O. Tegenfeldt Han Cao Stephen Y. Chou Edward C. Cox

We outline some of the possible applications of nanotechnology to modern molecular biology and discuss several technologies that can be used to make nanoscale confining environments (channels or post arrays) for long polymers such as DNA. A particular emphasis is placed on making large arrays using nonelectron beam lithography methods. We then discuss how focused ion beam (FIB) milling can be u...

2015
MICHAEL W. PORAMBO

The study of molecular ions is relevant to many areas of scientific interest. Mid-infrared laser spectroscopy functions as a useful tool for understanding the role of molecular ions in these areas. To this end, a broadly tunable mid-infrared difference frequency generation noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) system has been developed and characteri...

Journal: :Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 2004
I Miksík J Charvátová A Eckhardt T Cserháti E Forgács Z Deyl

Heptanesulfonic acid as ion-pairing agent was used for the separation of mixtures of low and high molecular mass peptides/proteins by capillary electrophoresis. The separation conditions used were: capillary 37 cm (30 cm to the detector) x 75 microm i.d., voltage 10 kV, phosphate buffer 50 mmol/l, ion-pairing agent heptanesulfonic acid at three different concentrations, namely, 0, 20 or 100 mmo...

Journal: :The journal of physical chemistry. A 2015
Iraklis Litinas Andreas D Koutselos

The conformations of flexible molecular species, such as oligomers and oligopeptides, and their interconversion in the gas phase have been probed by ion mobility spectrometry measurements. The ion motion is interpreted through the calculation of effective cross sections in the case of stable conformations of the macromolecules. However, when the molecular structures transform to each other as t...

Journal: :Clinical chemistry 1990
G Bodor R Roggeman J Turk

Benzoylecgonine (BEG) is the principal urinary metabolite of cocaine. For forensic drug testing, the presence of BEG in urine, suggested by a positive result for a screening immunoassay, must be confirmed by quantitative gas chromatographic/mass spectrometric (GC/MS) analysis, i.e., stable isotope dilution with a deuterium-labeled internal standard. GC/MS criteria for positivity also require ap...

2013
Alexandre Mourot Ivan Tochitsky Richard H. Kramer

Ion channels are transmembrane proteins that control the movement of ions across the cell membrane. They are the molecular machines that make neurons excitable by enabling the initiation and propagation of action potentials (APs). Rapid signaling within and between neurons requires complex molecular processes that couple the sensing of membrane voltage or neurotransmitter release to the fast op...

Journal: :Small 2011
Michael X Macrae Diana Schlamadinger Judy E Kim Michael Mayer Jerry Yang

Control of function in self-assembled molecular structures is a major challenge in supramolecular chemistry. [ 1–4 ] Ion channels, for instance, are pore-forming nanostructures typically comprising multiple molecular subunits assembled via noncovalent interactions. [ 5 ] These pores function by facilitating a fl ux of ions across the hydrophobic barrier of a lipid bilayer. For over a decade, ma...

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