Carrier position

The carrier position in the directly detected dimension may seem to be important however, in most cases it is not critical whatsoever. The one exception is when no quadrature detection in the remote dimension is desired (see below). In a general scenario the carrier can be placed anywhere in the spectral region of interest with no significant penalty on overall acquisition time. The only important requirement to be fulfilled is that the pulse(s) should cover the desired frequency range with sufficient uniformity (see also below). 

The thermopower or thermoelectric power is the electrostatic potential difference between the high and low temperature regions of a material with an impressed thermal gradient and zero electric current flow. The sign gives an indication of the sign of the charge carriers - positive for hole carriers. 

Until now, a recombination velocity of thermalized as well as hot carriers has been directly introduced in various models as a boundary condition independent of the carrier position in an insulator. This corresponds to the assumption jr(x) = const, and from Eq. (196), js =j0aiexp(—ax x), for the exponential character of the primary injection current jp = jo exp( —of x), follows. The source carriers are being thermalized with a probability v (per unit time) and rate eu N(x) equal to the carrier injection rate,... 

DNA in sera of virus carriers positive exclusively for antibodies to the hepatitis B core antigen. X Med. Virol. 1991 35 55-59 231. 

In the domain of contract sterilization, continuous processing in cobalt-60 radiation facilities has proved to be economically competitive with other sterilization methods, especially in the area of medical devices and packaging. When using a continuous carrier irradiator as described by Masefield et al., the materials are loaded onto the carriers and introduced into the irradiation chamber on a timed sequence. The carriers make four passes around the source, stopping at each carrier position for a certain time before being shuttled to the next position. The throughput is a function of the radiation dose required, the density of the device,... 

Figures 6 and 7 IS) summarize several important results obtained with cuprous oxide films at 200° and 20° respectively. Exposure to oxygen at a few microns pressure is seen to be accompanied by an abrupt fall in resistance (i.e., rise in conductivity) showing that the concentration of current carriers—positive holes in the case of CU2O—has increased. Oxygen is therefore being adsorbed as negative ions. The fact that recovery of the original conductivity is possible on evacuation at 200°, but not at 20°,...

The high-temperature superconductors can be classified by the two different types of charge carrier positive and negative. In the former the charge carriers are positive holes, but in the latter they are electrons. Positive charge carriers are the most common. 

Nahir TM, Buck RP, Transport processes in membranes containing neutral ion carriers, positive ion complexes, negative mobile sites, and ion pairs. J. Phys. Chem. 1993 97 12363-12372. 

In previous chapters we considered elementary crystal excitation taking into account only the Coulomb interaction between carriers. From the point of view of quantum electrodynamics (see, for example, (1)) such an interaction is conditioned by an exchange of virtual scalar and longitudinal photons, so that the potential energy, corresponding to this interaction, depends on the carrier positions and not on their velocity distribution. As is well-known, the exchange of virtual transverse photons leads to the so-called retarded interaction between charges. 

Each high quality sample (or group of similar samples) needs to be carefully shimmed and locked. As a minimum set of optimizations the pulse width and carrier position should be accurately established. These simple parameters should provide the backgroimd for at least manageable suppression. More complicated sequences may require further optimizations that will be discussed in greater detail in the following sections. 

A broad asymmetric peak makes the selection of the carrier position difficult since a compromise frequency must be selected to immediately saturate the greatest number of spins and then again during exchange with the other resonances. As the symmetry of the resonances in the sample improves (most likely through shimming) and the peaks become taller and narrower, the ideal presaturation position becomes evident. 

Lastly, it is commonly assumed that the relaxation rate of all solute atoms is consistent, which is not the case for multiple compounds in a single sample (e.g. metabonomics). Calibrations must be applied to any standard database for identification based on relative rates of relaxation, and therefore intensity of peaks. Different functional groups in the same molecule can have different spin-lattice relaxation rates as would more flexible regions of large molecules. For extremely accurate measurements the calibration of signal loss is also frequency dependent (i.e. distance to carrier position is proportional to intensity variation) due to the profile of the hard pulses. 

Each of the sequences was optimized with appropriate parameters (see figure legend) and presented at the same vertical scale for direct comparison. Standard parameters such as the 90° pulse width, sweep width, acquisition times, presaturation periods and powers, carrier positions and so on were maintained for each... 

A) Presaturation with optimized carrier position and pulse width that was used for all subsequent hard pulses, (B) Presat90 with the same parameters, (C) PresatlSO with an independently optimized 180° pulse length, (D) WEFT/NOESY with the same carrier and pulse width as optimized in the previous experiments and a 100 ms mixing time, (E) WET (118 us inter-pulse delay) with optimized... 

Finally, a comparison of the solvent suppression pulse sequences was performed with purposeful errors in pulse width (—10%) or carrier position (—4 Hz). 

The biochemical evidence reviewed here suggests that the ascorbic system may act as a carrier positioned between either coenzyme I or II and the terminal oxidase. It emphasizes the role of dehydroascorbic acid as hydrogen acceptor, the concentration of which, rather than the concentration of ascorbic acid, might be expected to determine the respiratory changes through this channel. 

The conduction mechanism is substantiated through the proton transfer/hopping between a proton donor and a proton acceptor in combination to the ability of the proton carrier (positive ion) to rotate and move so that it will transfer the proton to a negative ion according to reaction (2). As reported by Ma et al., the immobiU-zation of phosphoric acid molecules in the flame of the polymer membrane chains results in proton conductivity values one order of magnitude below the corresponding proton conductivity of pure phosphoric acid. 

Glycosylated carrier (Positive charge capped by blocompatible carrier)... 

The AYPEX machine design separates yam carrier actuation and yam carrier positioning (Figure 7.18). 

The separation of yam carrier actuation and yam carrier positioning allows for individual movements of each track or column. The track or column displacement value is independent of the number of empty yam carrier spaces in the track or column and thus of the yam carrier positions. This makes the AYPEX braiding suitable for the fabrication of complex braids, that is, with complex cross sections or variable cross-sectional area. 

Top When a source of electricity is connected as shown,an electric current flows. Note the direction offlow of charge carriers (positive holes and electrons). Boffom When the wire connections are reversed, no current flows. Note the depletion of charge carriers near the junction of the two semiconductors. 

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