Concentration instantaneous

It is assumed that the -hexane concentration instantaneously reaches a balance between alveolar air and arterial blood and the n-hexanc concentration in venous blood is in constant and dynamic balance with the corresponding tissue concentrations. 

The steady-state approximation is a more general method for solving reaction mechanisms. The net rate of formation of any intermediate in the reaction mechanism is set equal to 0. An intermediate is assumed to attain its steady-state concentration instantaneously, decaying slowly as reactants are consumed. An expression is obtained for the steady-state concentration of each intermediate in terms of the rate constants of elementary reactions and the concentrations of reactants and products. The rate law for an elementary step that leads directly to product formation is usually chosen. The concentrations of all intermediates are removed from the chosen rate law, and a final rate law for the formation of product that reflects the concentrations of reactants and products is obtained. 

The regeneration rate constants of Cu" -saturated resin in the presence of aqueous ammonia solutions are independent of resin amounts and dependent upon NH OH concentration. Instantaneous regeneration fractions of the resin are independent of resin amounts and NH.OH concentrations in reaction controlled cases, shown in Figure 9. The reaction rate controlled model is applicable to the regeneration of copper-saturated Dowex XFS 4195.02 resin in solutions with NH OH concentrations ranging from 1 - 2 N. 

Here we see that the pulse is injected at time "zero," the concentration instantaneously jumps discontinuously to a magnitude of 0.1, and then begins to descend exponentially as a function of time. This is the characteristic curve we should see if the unit is well mixed. 

Methods employed to attain the desired plasma concentration instantaneously, or very rapidly, and then maintain it as long as desired, including indefinitely. 

Calculation of the loading dose (DJ necessary to attain the desired plasma concentration instantaneously and the infusion rate (Q) necessary to maintain the plasma concentration at that concentration. 

Theophylline is relatively insoluble in an aqueous vehicle and, so, there is a practical difficulty in the administration of theophylline in that form. Therefore, aminophylline, which is the water-soluble salt (salt value of 0.8 to 0.85) of theophylline, is used. In this example, the salt value suggests that 100 mg aminophylline will provide 80-85 mg of theophylline. In other words, if the calculated loading dose required for attaining the desired theophylline plasma concentration instantaneously is 80 mg, then 100 mg of aminophylline must be administered. Failure to take into consideration the salt value, in this example, will result in 20% error. 

Show the profile (rectilinear paper) of loading dose necessary to attain a true steady-state plasma concentration instantaneously against the systemic clearance or against the degree of renal impairment (assuming that apparent volume of drug distribution remains unaffected). 

The calculations in parts (f) and (g) support the theory that a smaller dose given more frequently will yield greater drug accumulation and smaller drug fluctuation, h. It has already been determined that administration of 300 mg aminophylline (equivalent to 237 mg theophylline), every 8h yields a peak steady-state theophylline plasma concentration of 14.44pgmL . The following equation allows determination of the loading dose (Di) necessary to attain this theophylline plasma concentration instantaneously. 

One can safely say that aniline polymerization involves progressive nucleation with a two-dimensional growth mechanism at low monomer concentration. Instantaneous nucleation leads to the formation of an inhomogeneous material where phases segregate into protonated metallic islands embedded in a sea of insulating islands. This microscopic non-uniformity sometimes develops into macroscopic morphology which will not be reflected significantly in the peak... 

FIGURE 13.2 The scaling fit factors (Equation 13.15). s=0.5 in the limit of diffusion controlled initiation, and s=0 in the limit of decomposition controlled initiation. The sohd points are from fits to separate reactions under specific Am and initiator concentrations, whereas the crosses show intrareactional crossover from decomposition control to diffusion control averaged over many reactions where the crossover is prominent due to starting Am and initiator concentrations. Instantaneous molar fraction of VB, inst.vB versus conversion for batch and two feed rates during VB/ AM free radical copolymerization reactions. Adapted with permission from Kreft T, Reed WF. Direct monitoring of the crossover from diffusion-controlled to decomposition-controlled initiation in free radical polymerization. Macromol Chem Phys 2008 209 2463-2474. 

An intermediate is assumed to attain its steady-state concentration instantaneously, decaying slowly as reactants are consumed. An expression is obtained for the steady-state concentration... 

Ceiling exposure. This is the concentration that should not be exceeded, even instantaneously. 

The method is based on the international standard ISO 4053/IV. A small amount of the radioactive tracer is injected instantaneously into the flare gas flow through e.g. a valve, representing the only physical interference with the process. Radiation detectors are mounted outside the pipe and the variation of tracer concentration with time is recorded as the tracer moves with the gas stream and passes by the detectors. A control, supply and data registration unit including PC is used for on site data treatment... 

The method implies injection of a mixture of 3 radioactive tracers each being distributed into one of the 3 phases. The tracers must show such differences in the emitting y-radiation energy spectra that they can be simultaneously detected by on line y-spectrometry. Candidate tracers are Br-82 as bromobenzene for oil, Na-24 or La-140 for water, and Kr-85 for gas. The tracers are injected simultaneously at a constant rate into the flow in the pressurised pipe, and the concentration is detected as series of instantaneous measurements taken downstream as illustrated in figure 2. 

O, a large current is detected, which decays steadily with time. The change in potential from will initiate the very rapid reduction of all the oxidized species at the electrode surface and consequently of all the electroactive species diffrising to the surface. It is effectively an instruction to the electrode to instantaneously change the concentration of O at its surface from the bulk value to zero. The chemical change will lead to concentration gradients, which will decrease with time, ultimately to zero, as the diffrision-layer thickness increases. At time t = 0, on the other hand, dc-Jdx) r. will tend to infinity. The linearity of a plot of i versus r... 

Figure B2.5.7 shows the absorption traces of the methyl radical absorption as a fiinction of tune. At the time resolution considered, the appearance of CFt is practically instantaneous. Subsequently, CFl disappears by recombination (equation B2.5.28). At temperatures below 1500 K, the equilibrium concentration of CFt is negligible compared witli (left-hand trace) the recombination is complete. At temperatures above 1500 K (right-hand trace) the equilibrium concentration of CFt is appreciable, and thus the teclmique allows the detennination of botli the equilibrium constant and the recombination rate [54, M]. This experiment resolved a famous controversy on the temperature dependence of the recombination rate of methyl radicals. Wliile standard RRKM theories [, ] predicted an increase of the high-pressure recombination rate coefficient /r (7) by a factor of 10-30 between 300 K and 1400 K, the statistical-adiabatic-chaunel model predicts a...

The absorption of a light pulse instantaneously generates reactive species in high concentrations, either tlirough the fomiation of excited species or tlirough photodissociation of suitable precursors. The reaction can... 

Place 2 ml. of the periodic acid reagent in a small test tube, add one drop (no more—otherwise the silver iodate, if formed, will fail to precipitate) of concentrated nitric acid, and shake well. Add one drop or a small crystal of the compound to be tested, shake the mixture for 15-20 seconds, and then add 1-2 drops of 3 per cent, silver nitrate solution. The instantaneous formation of a white precipitate of silver iodate is a positive test. Failure to form a precipitate, or the appearance of a brown precipitate which redissolves on shaking, constitutes a negative test. 

We shall proceed on the assumption that [A] o and [B] o are equal. As noted above, the case of both reactive groups on the same molecule is a way of achieving this condition. Accordingly, we rearrange Eq. (5.12) to give the instantaneous concentration of unreacted A groups as a function of time ... 

The instantaneous monomer concentration must be used. Except at the azeotrope, this changes as the conversion of monomers to polymer progresses. As in Sec. 7.2, we assume that either the initial conditions apply (little change has taken place) or that monomers are continuously being added (replacement of reacted monomer). 

Properties. Xanthan gum is a cream-colored powder that dissolves in either hot or cold water to produce solutions with high viscosity at low concentration. These solutions exhibit pseudoplasticity, ie, the viscosity decreases as the shear rate increases. This decrease is instantaneous and reversible. Solutions, particularly in the presence of small amounts of electrolyte, have exceUent thermal stabiHty, and their viscosity is essentially constant over the range 0 to 80°C. They are not affected by changes in pH ranging from 2 to 10. 

The dispersion model is typically used to determine the downwind concentrations of released materials and the total area affected. Two models are available the plume and the puff. The plume describes continuous releases the puff describes instantaneous releases. 

Iodine dissolves without reaction in concentrated sulfuric acid and with concentrated nitric acid it reacts to form iodine pentoxide (47). Iodine reacts with alkah metal hydroxide solutions to form the corresponding hypoiodite and the rate of the reaction increases with the alkaU concentration and temperature. At 50°C, the reaction is almost instantaneous ... 

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