Magnetic forces

The arrows indicate the direction of magnetic forces Magnetic forces on the spiral arc... 

On the basis of these observations, an interesting formation of nanostructures consisting of SWNTs was probably achieved by magnetic force, magnetic orientation, interaction of induced magnetic moment of SWNTs due to strong magnetic fields, and self-assembly of SWNTs due to hydrophobic interaction in aqueous solution and so on [46, 48]. 

Scientists measure many different quantities—length, volume, mass (weight), electric current, temperature, pressure, force, magnetic field intensity, radioactivity, and many others. The metric system and its recent extension, Systeme International d Unites (SI), were devised to make measurements and calculations as simple as possible. In this chapter, length, area, volume, and mass will be introduced. Temperature will be introduced in Sec. 2.7 and used extensively in Chap. 11. The quantities to be discussed here are presented in Table 2-1. Their units, abbreviations of the quantities and units, and the legal standards for the quantities are also included. 

Contact Non-contact Intermittent contact Lateral force Magnetic force Thermal scanning... 

T0429 International Process Systems, Inc., High-Force Magnetic Separators T0452 Joule-Heated Vitrification—General... 

Magnetic Field. Particles of magnetic materials are influenced by magnetic forces. Magnetic fields are rarely used in particle size characterization. 

Long range attractive forces serve to bring the particle to the surface and to provide the basis for the contact. The forces involved may include van der Waals forces, magnetic attraction, and electrostatic forces. 

With these assumptions the equation of motion - involving the forces magnetic (F j), drag (Fj), and buoyancy (F ) - is written as... 

Magnetic force Magnetic field of the surface is imaged... 

The AFM cantilever is so thin and sensitive that it can sense the minute surface forces, such as van der Waals forces, magnetic forces, electrostatic forces, etc. It allows AFM to be used not only to investigate surface topography, but also to probe the physical, chemical, and magnetic properties of surfaces. 

The external volume forces f (gravitational forces, magnetic forces, etc.) are generally negligible in gas flow. It is even more the case in gas microflows, since the volume over surface ratio decreases with the characteristic length L, and consequently, in microscale geometries, volume effects may be neglected when compared to surface effects. 

Atomic Force Microscopes (AFMs). The AFM operates in essentially the same manner as the STM, except that its function is to maintain a constant measured electrical force between the probe tip and the atomic surfece being scanned. In this function, the probe tip follows the shape of the atomic surfaces directly, rather than measuring a property difference that changes according to the shape of the surface. Several different modes of operation are available within this context, such as constant contact, non-contact, intermittent contact, lateral force, magnetic force, and thermal scanning. Each mode provides a different type of information about the surfece atoms. 

Scanning probe microscopes allow examination of surfaces at the atomic scale, with resolutions as hne as 10 picometers (10 meters). Even the most cursory examination of a surfece image from a scanning probe microscope reveals that at the atomic level an assumed perfectly smooth surface consists instead of a series of bumps and depressions reminiscent of what one would observe in a layer of golf balls, marbles, or any other spherical object. Additionally, quantum effects such as van der Waals forces, magnetism, and electronic interactions, and the chemical nature of the material, are important components of friction at the atomic level. The accumulation of effects from the atomic level to the normal size of the object determines how friction is generated between material olyects. 

In addition to force-induced alignment, carbon nanotubes can be aligned by the geometric constraints (created by a liquid crystalline phase). Due to the unique properties of the liquid crystals, their geometry can be easily modified by the force, magnetic and electric field. For example. Lynch et al. aligned... 

Magnetization The exposure of a magnetic material to a magnetizing current, field, or force. Magnetizing force The force producing magnetization. 

A velocity dependent force (magnetic force) is considered in Prob. 2.2. 

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