SUBJECTS dead space

Simpler optimization problems exist in which the process models represent flow through a single pipe, flow in parallel pipes, compressors, heat exchangers, and so on. Other flow optimization problems occur in chemical reactors, for which various types of process models have been proposed for the flow behavior, including well-mixed tanks, tanks with dead space and bypassing, plug flow vessels, dispersion models, and so on. This subject is treated in Chapter 14. 

Reflectance cuvettes for tablets, which provide spectra subject to strong scattering arising from dead spaces between tablets placed in the cuvette. 

Healthy subjects have hardly any alveolar dead space. However, disease may increase the dead space in the alveoli [15]. This might be of importance when alveolar deposition is desired, for example to obtain systemic absorption. 

The total accessible pore volume may be measured by the amount of adsorbate at the saturation pressure of the adsorptive, calculated as liquid volume, provided the adsorption on the external surface can be neglected or can be evaluated. The accessible pore volume may be different for molecules of different sizes. A method which is not subject to the effect of the external surface is the determination of the dead space by means of a non-sorbable gas (normally helium) in conjunction with the determination of the bulk volume of the adsorbent by means of a non-wetting liquid or by geometrical measurements. 

Any experiment suffers to some extent from the influence of various uncontrolled factors, such as mass- and heat-transfer regimes in different parts of the reaction system, irregularity of temperature fields and flow profiles, dead spaces, poor mixing, and independent flow of reactants, wall chemistry and its variation with time, etc. Another problem is a correlation between signals received from different sensors and real values of measured physical parameters. There is a voluminous literature on this subject here we just mention the pitfalls related to the measurements of surface and gas temperatures in the course of reaction involving very active radical species. 

In addition to the static lung volumes just identified, there are several time-dependent volumes associated with the respiratory act. The minute volume (MV) is the volume of air per breath (tidal volume) multiplied by the respiratory rate (R), that is, MV = (TV) R. It is obvious that the same minute volume can be produced by rapid shallow or slow deep breathing. However, the effectiveness is not the same, because not all the respiratory air participates in gas exchange, there being a dead space volume. Therefore the alveolar ventilation is the important quantity which is defined as the tidal volume (TV) minus the dead space (DS) multiphed by the respiratory rate R, that is, alveolar ventilation = (TV-DS) R. In a normal adult subject, the dead space amounts to about 150 mL, or 2 mL/kg. 

To inhale the aerosols labelled with radioisotopes (radioactive aerosols), subjects breathe through a mouth piece. The volume of air in the mouth and tracheo-bronchial region is respiratory dead space, and the activity reaching the pulmonary region depends on the volume of air inhaled as well as the deposition in the tracheo-bronchial region. To obtain reproducible results, subjects take breaths of predetermined volume, and the breathing cycle is also standardised, usually at 14 or 15 breaths/min. Exhaled aerosol is collected on a filter, and the deposition in the mouth also estimated, so that the deposition in the lung (tracheo-bronchial... 

The input-output relationships of the chemical plants are subject to several endogenous and exogenous disturbances. For example, increases in the metabolic production of COj during muscular exercise, PCOj in the inspired air, and respiratory dead space during rebreathing—all contribute to an increase in COj load to the lung. The added COj is eliminated by an increase in pulmonary ventilation, but the effectiveness of the control action in restoring varies considerably with the type of disturbance. 

Remember that being on deadline does not allow time for a lengthy explanation or "the history of..." Try to find out specifically what the reporter needs to know, then provide answers (or help restructure their questions) without lecturing. Their impatience is not with the subject they re facing white space or dead air and the clock s ticking. 

In reviewing the progress made in chemical industries proper, we are met with such a condition of interdependence that it is impossible to avoid overlapping of the subjects to be treated. Moreover, the steps made in the improvement and development of processes, and in the evolution of new products, are so numerous that space will not allow of a comprehensive scheme. Indeed, tbe library of the Patent-office, one of the best for technological literature, cannot contain all that is due to chemists, nor disclose to which chemists the credit should be given for many important advances. We must, perforce, recognise, however, that science is the basis of all substantial development in the industrial arts, and that the ride of thumb is dead. 

Most construction work is done in well-ventilated areas. Under normal circumstances, even trenches are not considered confined or enclosed spaces because there is enough natural ventilation. But a trench, as well as other enclosed areas at construction sites, can be deadly. Such areas are subject to the accumulation of toxic or flammable contaminants or can develop an oxygen deficiency. To ensure employee safety in confined spaces you must ... 

The Immobilization of cells Introduced In the seventies used the same preparation techniques as those used with enzymes (Table 3), because according to Chlbata (1983) "Immobilized cells In the same manner as Immobilized enzymes are physically or chemically confined or localized In a certain defined region of space with retention of their catalytic activities, and which can be used repeatedly and continuously". These microbial systems are quasl-lmmoblllzed enzymes. However, the latter are localized within the cell and thus subject to a special protection. There are no losses of activity during Isolation and preparation, especially In the case of Intra-cellular enzymes. Principally we have to differentiate between two borderline cases. In the first preferably only a single enzyme Is active (e.g. aspartase) the cell Is damaged or dead (Table 4). In the second case several blocatalysts or the complete enzyme system of the cell... 

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