Low-mass

Characteristic Low-Mass Neutral Fragments from the Molecular Ion... 

When multicharged ions are formed, the simple rule of thumb used widely in mass spectrometry that m/z = m because, usually, z = 1 no longer applies for z > 1 then m/z < m, and the apparent mass of an ion is much smaller than its true mass. Accurate mass measurement is much easier at low mass than at high, and the small m/z values, corresponding to high mass with multiple charges, yield accurate values for the high mass. 

By altering the electric fields in a consistent manner, the masses of all ions formed in the source can be scanned sequentially from low mass to high or vice-versa to give a mass spectrum. 

Eig. 17. Cross-sectional schematic of a microbolometer photodetector. Micromachining is used to constmct small, very low mass detectors. The dimension... 

Eig. 18. Microbolometer (a) array portion showing pixels on a 50-pm pitch. Each pixel is coimected to a readout amplifier in the supporting siUcon IC chip, (b) Detector having a 35 x 40 pm active area. The serpentine arms give excellent thermal isolation and the low mass results in a 10-ms response time, ideal... 

Contaminants and by-products which are usually present in 2- and 4-aminophenol made by catalytic reduction can be reduced or even removed completely by a variety of procedures. These include treatment with 2-propanol (74), with aUphatic, cycloaUphatic, or aromatic ketones (75), with aromatic amines (76), with toluene or low mass alkyl acetates (77), or with phosphoric acid, hydroxyacetic acid, hydroxypropionic acid, or citric acid (78). In addition, purity may be enhanced by extraction with methylene chloride, chloroform (79), or nitrobenzene (80). 

Delayed Proton and Neutron Decays. By means of a variety of nuclear reactions, as weh as the spontaneous fission of synthetic nucHdes, large numbers of isotopes of some elements have been produced. For example, whereas the only stable isotope of Cs (Z = 55) is Cs (JV = 78), ah of the Cs isotopes from Cs where 77 = 59 and = 0.57 s, to Cs where N = 93 and = 0.13 s, have been observed. At the low mass end of this series, the last proton is only loosely bound, and at the high mass end, the last neutron is only loosely bound. 

T] Low M.T. rates. Low mass-flux, constant property systems. Ns, % L local k. Use with arithmetic difference in concentration. Coefficient 0.323 is Blasius approximate solution. 

T] Constant-property liquid film with low mass-transfer rates. Use arithmetic concentration difference. 

S] Low mass-flux with constant property system. Use with arithmetic concentration difference. 

NflaNsc) < 10,000 Nrs < 1-0. Constant sphere diameter. Low mass-transfer rates. [146] p. 214... 

Fits some, but not all, data. Low mass transfer rate. = mean molecular weight of dispersed phase tf= formation time of drop. k[, i = mean dispersed liquid phase M.T. coefficient kmole/[s - m" (mole fraction)]. 

Wetted-waU or falhng-film columns have found application in mass-transfer problems when high-heat-transfer-rate requirements are concomitant with the absorption process. Large areas of open surface are available for heat transfer for a given rate of mass transfer in this type of equipment because of the low mass-transfer rate inherent in wetted-waU equipment. In addition, this type of equipment lends itself to annular-type coohng devices. 

Matrix-assisted laser desorption/ionization (MALDI) is widely used for the detection of organic molecules. One of the limitations of the method is a strong matrix background in low-mass (up to 500-700 Da) range. In present work an alternative approach based on the application of rough matrix-less surfaces and known as surface-assisted laser desoi ption/ionization (SALDI), has been applied. 

Pinch Point—This is defined as the differenee between the exhaust gas temperature leaving the evaporator seetion and the saturation temperature of the steam. Ideally, the lower the pineh point, the more heat reeovered, but this ealls for more surfaee area and, eonsequently, inereases the baek-pressure and eost. Also, exeessively low pineh points ean mean inadequate steam produetion if the exhaust gas is low in energy (low mass flow or low exhaust gas temperature). General guidelines eall for a pineh point of 15-40°F (8-22 °C). The final ehoiee is obviously based on eeonomie eonsiderations. 

Flow Low mass flow indicated. Mass flow error. Transmitter zero shift. Measurement is high. Measurement error. Liquid droplets in gas. Static pressure change in gas. Free water in fluid. Pulsation in flow. Non-standard pipe runs. Install demister upstream heat gas upstream of sensor. Add pressure recording pen. Mount transmitter above taps. Add process pulsation damper. Estimate limits of error. 

Consider first a dilute phase pneumatic transfer system operating at high velocity and relatively low mass flow density. As discussed in 6-3.1 this... 

It is very evident in Figure 3 that the chemical complexity of Hasteloy presents special problems for mass spectrometric analysis using a quadrupole mass spectrometer with low mass resolution. Molecular ions comprised of combinations of matrix and plasma atoms are formed in abundance and will obscure many elements... 

The ( ) factor enables temperature rises to be corrected for heat lost to the container or vessel. The ( ) factor approaches the value of one for large vessels and for extremely low-mass vessels. 

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