Clearance times

The study found that the slot-type inlet at the bottom of the cabinet door resulted in higher pressure losses (lower CJ than the diffuser or perforated plate inlet. The exhaust configuration had little effect on Q or tracer gas clearance time. The study also concluded that an exhaust rate 0.118 m s for a two-cylinder cabinet was sufficient as little improvement was seen with an increase to 0.165 m s F" The slotted inlet took longer to clear a leak than either the perforated plate or diffuser inlet. Measured coefficients of entry for a two-cylinder gas storage cabinet are shown in Table 10.9. 

Problems with other normal mucosal defense mechanisms may also contribute to the development of GERD, including prolonged acid clearance time from the esophagus, delayed gastric emptying, and reduced mucosal resistance. 

Key AUC Area under the curve, Cmax maximal serum concentrations, Tmax time to reach peak concentrations, Vd volume distribution, K rate constant for elimination, T2 Elimination half-life, and CIT Total body clearance time. (Wojcicki et al. 1995)... 

A model based on the assumption that a metabolite is present within a single compartment with defined rate constants for absorption and elimination of the metabolite. The rate of appearance of a tracee and the infusion of tracer are assumed to take place in a single pool that is instantly well-mixed. Wolfe has described in detail how the constant tracer infusion method allows one to calculate half-life, pool size, turnover time, mean residence time, and clearance time. 

Chylomicron metabolism. Smoke, administered to rats injected intravenously with C- and H-labeled chylomicrons, produced no difference in the initial plasma clearance time of labeled chylomicrons between smoke-treated and control animals. Hepatic uptake of chylomicron cholesterol was slower in smoke-treated animals than in controls. More labeled chylomicrons remained in the heart of smoke-treated rats than controls . 

The total amount of drug eliminated is equal to the clearance time as a product of the AUC (i.e., clearance x AUC). This product is also co-equal to the amount that is absorbed (i.e., F x Dose) as is presented in Eq. (3.15) ... 

On the other hand, particles from fossil fuel combustion and gas-to-particle conversion are generally much smaller (< 2.5-/Am diameter) and fall in the respirable size range. These particles can reach the alveolar region where gas exchange occurs. This region is not coated with a protective mucus layer, and here the clearance time for deposited particles is much greater than in the upper respiratory tract hence the potential for health effects is much greater (Phalen, 1984). 

Artemisinins are also proving to have outstanding efficacy for the treatment of complicated falciparum malaria. Large randomized trials and meta-analyses have shown that intramuscular artemether has an efficacy equivalent to that of quinine and that intravenous artesunate is superior to intravenous quinine in terms of parasite clearance time and—most important—patient survival. Intravenous artesunate also has a superior side-effect profile compared with that of intravenous quinine or quinidine. Thus, intravenous artesunate will likely replace quinine as the standard of care for the treatment of severe falciparum malaria, although it is not yet widely available in most areas. Artesunate and artemether have also been effective in the treatment of severe malaria when administered rectally, offering a valuable treatment modality when parenteral therapy is not available. 

On the other hand, acidic drugs tend to ionize under conditions of alkaline pH and so are unable to permeate the renal tubular epithelium and are preferentially excreted. Tire converse applies to conditions of acidic urinary pH. This has been demonstrated experimentally for many drugs weak bases are excreted more rapidly in acidic urine, whereas weak acids are excreted more rapidly in alkaline urine. In the horse, phenylbutazone, which is a weak organic acid with a pKa of 4.6, has a more delayed clearance time under conditions of aciduria than under conditions of alkaline urine. 

Cambendazole has been implicated in teratogenic effects in pregnant ewes. Hence, long slaughter clearance times of 21 and 28 days have been recommended for treated cattle and sheep, respectively. 

The signs and symptoms considered were rhinorrhea, nasal obstruction and sneezing. The morphological structure of the nasal cavities was examined with anterior rhinoscopy. Skin prick tests, nasal provocation tests, nasal microbiological tests and mucociliary clearance time (MCT) were used to identify the causal factors. The skin prick tests were used to... 

The term A should be taken as the most restrictive area for liquid flow in the downcomer outlet. Usually, this is the area under the downcomer apron (i.e., the downcomer clearance times the length of the segmental downcomer), but not always. For instance, if an inlet weir is used and the area between the segmental downcomer and the inlet weir is smaller than the area under the downcomer apron, the smaller area should be used. 

The mucus layer also bathes the cilia of ciliated epithelial surface cells and provides a stimulus for ciliary motility (i.e., ciliary beating). The cilia consist of microtubules with a 9 + 2 configuration (nine pairs of peripheral microtubules and two central microtubules) that beat rhythmically to rapidly move mucus from the anterior to the posterior portion of the nasal cavity. To successfully cross the nasal permeability barrier, peptide drugs must penetrate the mucus layer and cross the epithelial cell layer, and do so in a limited time, because mucociliary clearance will limit the time of exposure of the peptide to the absorptive surface [19-21,27-29], Typically, drugs or inspired particles that are delivered nasally are removed via mucociliary clearance, with a clearance time of approximately 15 min in humans however, this transit time can vary from person to person and can be impacted by the addition of mucoadhesive agents to the formulation [30-37],... 

While one production head might feel satisfied with a standard fault clearance time of three hours, another might insist on a service level of thirty minutes. 

Related to clearance time is the manner in which the nanoparticles attach to cells. Nanoparticles can be internalized or remain adhered to the surface. The mechanism is determined by the surface charge, adhesion properties, and chemical functionality of the cells with respect to the nanoparticle. 

Tracheobronchial deposition of such carriers may not be desirable as clearance on the mucociliary escalator will occur in a relatively short time providing insufficient time for release from these controlled-release systems. Alveolar deposition will, in contrast, result in extended clearance times which are dependent on the nature of the carrier particle and may therefore be a better option for the effective use of such carrier systems for pulmonary drag delivery. 

Reversed phase H P LC conditions have been used with good success in the analysis of low levels of specific alkaloids. For example, the toxicokinetics of methyllycaconitine were determined by analyzing mouse sera and tissue samples (kidney, brain, liver, muscle) with detection down to one part per billion using selected ion monitoring MS/MS conditions [66]. Similar procedures are being used to measure alkaloid clearance times in sheep sera for methyllycaconitine and deltaline (Gardner, unpublished data). 

Aeration in a slurry cause large ultrasonic attenuations making accurate particle size measurement impossible. Aerated slurry can be fed to a holding tank and ultrasonic measurements made once the aeration level has dropped low enough to allow meaningful measurements. Clearance times were found to be short enough for a baffled tank passive de-aeration system to be feasible. 

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