We study different configurations of permanent magnets and ferromagnetic circuit, in order to optimize the magnetic field for the so-called “magnetic tweezers” technique, for studing mechanical properties of DNA molecules. The magnetic field is used to pull and twist a micron-sized superparamagnetic bead, tethered to a microscope slide surface by a DNA molecule. The force applied to the bead mu...

We present the results of magnetic force microscopy investigations of domain structures in multilayer [Co (0.5 nm)/Pt (1 nm)]₅ thin film structures (denoted hereafter as Co/Pt) modified by additional Co capping layers and by ion irradiation. It is demonstrated that a Co capping layer essentially changes the domain structure and decreases the threshold of magnetization reversal, due to the forma...

A room temperature nuclear magnetic resonance force microscope (MRFM), fitted in a 1Tesla electromagnet, is used to measure the nuclear spin relaxation of H in a micron-size (70ng) crystal of ammonium sulfate. NMR sequences, combining both pulsed and continuous wave r.f. fields, have allowed us to measure mechanically T2 and T1, the transverse and longitudinal spin relaxation times. Because two...

High-speed atomic force microscopy (HSAFM) has enabled researchers to view the nanometer-scale dynamic behavior of individual biological and bio-relevant molecules at a molecular-level resolution under physiologically relevant time scales, which is the realization of a dream in life sciences. These high-speed imaging applications now extend to the cellular/bacterial systems with the use of a sm...

Introduction and Review Atomic Force Microscope (AFM) Spectroscopy is an AFM based technique to measure, and sometimes control the polarity and strength of the interaction between the AFM tip and the sample. Although the tip-sample interaction may be studied in terms of the energy, the quantity that is measured first is always the tip-sample force, and thus the nomenclature: force spectroscopy....

This paper describes the effects of induced magnetic field and partial slip on the peristaltic flow of a couple stress fluids in an asymmetric channel. The two dimensional equation of couple stress fluid are simplified by making the assumptions of long wave length and low Reynolds number. The exact solutions of reduced momentum equation and magnetic force function have been computed in wave...