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Model transition

Zhao and Rezkallah (1993), Rezkallah (1996), and more recently Lowe and Rezkallah (1999) developed two-phase flow transition models for micro-gravity channel flows based on liquid and gas Weber numbers. Zhao and Rezkallah (1993) suggested Wees 1 as the upper boundary for the surface tension-dominated zone, and Wees 20 as the lower boundary for the inertia-dominated zone. [Pg.196]

This is, beyond all doubt, the most important process and the only one which has been already tackled with theoretically. Nevertheless, the prediction given by the classical overbarrier transition model is not correct for this collision [9] and the modified multichaimel Landau-Zener model developed by Boudjema et al. [34] caimot explain the experimental results for collision velocities higher than 0.2 a.u.. With regard to the collision energy range, we have thus performed a semi-classical [35] collisional treatment... [Pg.341]

The cumulative curve obtained from the transit time distribution in Figure 9 was fitted by Eq. (48) to determine the number of compartments. An additional compartment was added until the reduction in residual (error) sum of squares (SSE) with an additional compartment becomes small. An F test was not used, because the compartmental model with a fixed number of compartments contains no parameters. SSE then became the only criterion to select the best compartmental model. The number of compartments generating the smallest SSE was seven. The seven-compartment model was thereafter referred to as the compartmental transit model. [Pg.411]

The seven-compartment transit model may be physiologically sound. We may visualize that the first half of the first compartment represents the duodenum the second half of the first compartment, along with the second and third compartments, the jejunum and the rest of the compartments the ileum. The corresponding transit times in the duodenum, jejunum, and ileum are 14, 71, and 114 min, respectively. Considering the volumes and flow rates in these three segments [71,72], such an assignment seems reasonable. [Pg.411]

The compartmental absorption and transit model was developed based on the transit model. The assumptions for the CAT model include the following. [Pg.411]

Figure 10 The fraction of dose absorbed as a function of the effective human permeability. (---) Compartmental absorption and transit model (Eqs. (59) or (60)) (—) single-... Figure 10 The fraction of dose absorbed as a function of the effective human permeability. (---) Compartmental absorption and transit model (Eqs. (59) or (60)) (—) single-...
L. X. Yu, G. L. Amidon. A compart-mental absorption and transit model for estimating oral drug absorption. Int.J. Pharm. 1999, 386, 119-125. [Pg.212]

A special case in dissolution-limited bioavailability occurs when the assumption of sink condition in vivo fails that is, the drug concentration in the intestine is dose to the saturation solubility. Class IV compounds, according to BCS, are most prone to this situation due to the combination of low solubility and low permeability, although the same could also happen for class II compounds, depending primarily on the ratio between dose and solubility. Non-sink conditions in vivo lead to less than proportional increases of bioavailability for increased doses. This is illustrated in Fig. 21.8, where the fraction of drug absorbed has been simulated by use of an compartmental absorption and intestinal transit model [35] for different doses and for different permeabilities of a low-solubility, aprotic compound. [Pg.506]

In the phase transition model (4) long wavelength modes are coupled to short wavelengths modes by nonlinear couplings (21). It is not known whether this model can be solved exactly except for numerical methods. [Pg.286]

The activities of the indole carbazimidamide derivatives 5 at the 5-HT4 receptor were measured in vitro using the field-stimulated LMMP-GPI preparation (Table 1) followed by in vivo investigations applying the gastric emptying and intestinal transit models in the guinea-pig and rat. [Pg.199]

The STM (Simplified Transition Model) estimates investment to bring hydrogen FCV costs to competitive levels, investment costs for building H2 infrastructure, GHG-emission reductions and oil savings over time. [Pg.462]

Transition modelling estimating the investments required to bring hydrogen and fuel-cell vehicles to cost competitiveness... [Pg.474]

To study this buy-down process for hydrogen and fuel-cell vehicles, the Simplified Transition Model (STM) was used to aggregate costs over the entire fleet, based on the fuel-cell vehicle and hydrogen infrastructure costs previously described ... [Pg.474]

The transition-state model for these cyclizations (Scheme 34) differs fundamentally from the well-established Beckwith-Houk transition model for radical cyclizations [130,146-148]. Thus, while both models invoke chairlike transition states, without excluding the possibility of twist boatlike systems in some instances, the Beckwith-Houk model involves full conformational... [Pg.41]

Refinement and expansion of these steady-state mass balance approaches has led to the development of dynamic models which allow for estimation of the fraction absorbed as a function of time and can therefore be used to predict the rate of dmg absorption [37], These compartmental absorption and transit models (CAT) models have subsequently been used to predict pharmacokinetic profiles of drugs on the basis of in vitro dissolution and permeability characteristics and drug transit times in the intestine [38],... [Pg.46]

Yu LX and Amidon GL (1999) A Compartmental Absorption and Transit Model for Estimating Oral Drug Absorption. Int J Pharm 186 pp 119-125. [Pg.70]

Keywords Absorption In silico Mixing tank Maximum absorbable dose Mass balance approach Compartmental absorption Transit models... [Pg.486]

The basis for all CAT models is the fundamental understanding of the transit flow of drugs in the gastrointestinal tract. Yu et al. [61] compiled published human intestinal transit flow data from more than 400 subjects, and their work showed the human mean small intestinal transit time to be 199 min. and that seven compartments were optimal in describing the small intestinal transit process using a compartmental approach. In a later work, Yu et al. [58] showed that between 1 and 14 compartments were needed to optimally describe the individual small intestine transit times in six subjects but in agreement with the earlier study, the mean number of compartments was found to be seven. This compartmental transit model was further developed into a compartmental absorption and transit (CAT) model ([60], [63]). The assumptions made for this CAT model was that no absorption occurs in the stomach or in the colon and that dissolution is instantaneous. Yu et al. [59] extended the CAT model... [Pg.496]

Phase transition models, oscillatory reactions, 39 92-97 Phenanthrene... [Pg.174]

In the context of the Monod-Wyman-Changeux concerted-transition model for allosteric effects, one usually considers the effects of specific site occupancy on the behavior of other binding sites. Thus, a more correct... [Pg.337]

Note that negative cooperativity cannot occur in the Monod-Wyman-Changeux allosteric transition model, because the dissociation constant is equivalent for all sites. Thus, positive cooperativity can only result in this binding mechanism as a consequence of the recruitment of binding sites from the T-state in an all-or-none transition to the R-state. Any occurrence of negative cooperativity can be regarded as prima facie evidence... [Pg.498]

Furthermore, the Pefr data can be integrated with solubility/dissolution data to predict the oral absorption from the solid dosage form (see Chapter 10). Gastrointestinal transit absorption model (GITA) [12, 13], advanced compartmental absorption and transit model (ACAT, GastroPlus), advanced drug absorption and metabolism model (ADAM, SimCYP) and so on have been reported as useful integration models (see Chapter 10). [Pg.121]

Another important advance adding to the value of PBPK modeling in the pharmaceutical industry are physiological, mechanistic models developed to describe oral absorption in humans and preclinical species. Oral absorption is a complex process determined by the interplay of physiological and biochemical processes, physicochemical properties of the compound and formulation factors. Physiologically based models to predict oral absorption in animals and humans have recently been reviewed [18, 19] and several models are now commercially available. The commercial models have not been published in detail because of proprietary reasons but in essence they are transit models segmenting the gastrointestinal tract... [Pg.223]


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See also in sourсe #XX -- [ Pg.169 ]




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ACAT model transit

Advanced compartmental absorption and transit model

Aldehydes transition-state model

Algebraic models electromagnetic transition intensities

Anh transition state model

Bimolecular reactions, collision model transition state theory

Biradicals transition state model

Boron enolates transition state model

Chelating transition state models

Cluster models structural transitions

Compartmental absorption and transit model

Complete state transition model

Concerted Transition or Symmetry Model

Concerted transition model

Concerted transition model application

Concerted transition model limitations

Concerted transition model postulates

Contrast structures phase transition models

Cram selectivity transition state models

Discrete models transition function

Discrete models transition states

Dressed-atom model dark transition amplification

Dual activation transition-state model

Elastic-contractile model proteins transition

Electrophilic aromatic substitution reactions transition state modeling

Enamines transition model

Entropy glass transition model

Felkin-Ahn transition state model

First-order phase transition lattice models

Force field methods transition structure modelling

Friedel transition state model

Gastrointestinal Transit Absorption model

Gaussian model, phase transitions

Glass transition Adam-Gibbs model

Glass transition models based on heterogeneity

Glass transition temperature model

Glass-transition temperature ligand field models

Houk transition state model

Houk-List transition state model

Houk’s transition-state models

Intrinsic glass transition, model

Inverse temperature transitions model protein

Kauzmann temperature, glass transition entropy model

Landau model, phase transitions

Localized transition model

Markov transition model

Melting Model for a Conventional Transition Section Using Screw Rotation Physics

Michael addition closed transition state model

Model Calculation for the Glass Transition with an Underlying Heating Rate

Model configurations, transition moments

Model proteins transitions

Model transit

Model transit

Modeling Drug Transit in the Intestines

Modeling of Glass Transition

Modeling of the Glass Transition

Modeling with Transition-metal Complexes

Models of spin transition

Models of the glass transition

Models, for transition-metal

Molecular modelling transition metal complexes

Neolithic Transition Single-Species Models

Noncooperative transition model

Nuclear transition state model

Open transition state model

Organic chemistry fundamental reactions single-transition-state model

Oscillatory reactions phase transition models

Pharmacodynamics transit compartment model

Phase transition model

Phase transition models, oscillatory

Phase transitions ammonium triiodate crystal model

Phase transitions modelling

Phase transitions, diffusion models

Physical Models of Elementary Processes, Transition Probabilities, and Kinetic Coefficients

Probability, models, transition

Seebach-Eschenmoser transition state model

Sidechain transitions, model

Simple Model for Metal-Insulator Transition

Simple Model of a Transition Metal

Statistical Model Showing Synchronization-Desynchronization Transitions

Structural models, glass transition temperature

The Aldol Addition of Preformed Enolates - Stereoselectivity and Transition-state Models

The Denaturation Transition Poland-Scheraga Models

The JKR-DMT transition and Maugis-Dugdale (MD) Model

The Random Micelle Aggregation Model for Sphere-to-Rodlike Transition

The Schlogl model of first-order phase transition

The Schlogl model of second-order phase transition

The Symmetry Model Provides a Useful Framework for Relating Conformational Transitions to Allosteric Activation or Inhibition

Tilting transition, density functional model

Transition Blyholder model

Transition Chatt-Dewar-Duncanson model

Transition State Models for Proline-Catalyzed Reactions

Transition dipole coupling model

Transition elementary quantum-chemical model

Transition generic model

Transition metal model

Transition metal model construction

Transition models, lasers

Transition prediction model

Transition stale model

Transition state Zimmerman-Traxler model

Transition state modeling

Transition state modelling

Transition state models

Transition state models for

Transition state tetrahedral model

Transition state theories site model theory

Transition state theory statistical kinetic models

Transition state, Wheland model

Transition structure modelling

Transition, glass, hole model

Transition, glass, hole model modeling

Transition-dipole vector-coupling model

Transition-metal model complexes

Transition-state model thiol

Transition-state model, for solution reactions

Transition-state switching model

Transitional alternative fuel and vehicle model

Transitional boiling model

Transitioning five-step model

Transitions elastic-contractile model

Transitions model protein-water systems

Transitions model proteins, water

Transitions of regular structures two-state models

Two-state transition model

Zigzag Spin Model at F-AF Transition Point

Zipper transition model

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