Formulations feasibility

Originally ASTRA was developed on the base of existing models that have been converted into a dynamic formulation feasible for implementation in system dynamics and allowing for closure of the feedbacks between the models. Among these models have been the macroeconomic model, ESCOT (Schade et al., 2002) and the classical four-stage transport model, SCENES (ME P, 2000). The ASTRA model then runs scenarios for the period 1990 until 2030 using the first 12 years for calibration of the model. Data for calibration stem from various sources, with the bulk of data coming from the EUROSTAT (2005) and the OECD online databases (OECD, 2005). A detailed description of ASTRA is provided by Schade (2005). 

Answer. Temporal domain knowledge, physical and operational knowledge and spatial-related knowledge a multiechelon approach formulation, feasibility analysis, temporal structure, generation of separation sequences, internal spatial structure, behavior analysis, evaluation. 

The question of whether the sequential addition of surfactant molecules to the complex involves an addition to an aggregate unit or simply the adsorption of individual molecules followed by the aggregation process when the coil is saturated cannot be easily answered. In either case, a given polymer chain can accommodate only a limited number of surfactant molecules or aggregates. When the surfactant concentration exceeds the capacity of the polymer present to form the complex, additional surfactant appears to continue its life as usual until its normal cmc is reached. The values of the various surfactant-polymer interaction rate constants and their dependence on experimental conditions (e.g., temperature, solvent, ionic strength, pH) serve as a basis for formulating feasible descriptions of the molecular processes involved in the interactions. The combination of macroscopic and molecular information can provide valuable insight into the overall process. 

Based on the results of the feasibility study, and assuming that at least one option is economically viable, a field development plan can now be formulated and subsequently executed. The plan is a key document used for achieving proper communication, discussion and agreement on the activities required for the development of a new field, or extension to an existing development. 

In order to generate a candidate EAR, one should consider potential raw materials and by-products, satisfaction of stoichiometric conditions, assurance of thermodynamic feasibility, and fulfillment of environmental requirements. These issues can be addressed by employing an optimization formulation to identify an overall reaction that yields the desired product at maximum economic potential while satisfying stoichiometric, thermodynamic, and environmental constraints. For a more detailed description of this optimization program, the reader is referred to Crabtree and El-Halwagi (1994). 

Once v, is determined under one set of conditions, the procedure is then repeated, varying the concentrations of reactant, catalyst, buffer, etc. The resulting family of v, values can be used to formulate the rate law. This desirable method is probably deserving of wider use in general chemical reactions, just as it is used in biochemical reactions. The method of initial rates is, however, not without its problems. For one thing, the accurate determination of product in the presence of so much substrate is not always feasible. For another, this approach may conceal important effects that come into play only later in the course of the reaction. If the method of initial rates is used, separate experiments must be performed to check these points. 

In spite of the high polarity of PA6, identification of additives was also feasible in formulations of PA6/additive dissolutions, although with decreased sensitivity. Hostavin N 20, Irganox B 1171, Tinuvin 320 and Tinuvin 350 can be determined in PA6 in technical concentrations, although the sensitivity is less than for nonpolar polymers, such as polyolefins. This was tentatively explained as follows. In a nonpolar polymer matrix, the electronically excited polar additive molecule can easily be desorbed. In the polar polyamide matrix, desorption of the additives is hindered by strong polar interactions (e.g. hydrogen bridges) between the excited analytes and the polymer matrix. This hinders selective desorption of the additives by laser irradiation. However, in a polymer/additive matrix-modified solution, evaporated to dryness, the interactions between the polar... 

Most hydraulic fluid preparations start as chemical mixtures. For instance, there is a considerable area of overlap in the specific petroleum hydrocarbon chemicals contained in the mineral oil and polyalphaolefin hydraulic fluids. For all classes of hydraulic fluids, there may be similarities with other original products intended for use as lubricants. The complications involved in documenting the environmental fate of mixtures increase under conditions encountered at many NPL sites, where it may be hard to determine the precise original product associated with chemicals identified at an area in need of remediation. In most instances, available peer-reviewed literature, supplemented with data obtained from manufacturers of particular formulations and information in trade magazines, can supply information about the original hydraulic fluid preparations. At NPL sites, site-specific evaluations of specific chemicals may be the only feasible way to address concerns over environmental fate and potential exposure risks. 

Formulation strategies for stabilization of proteins commonly include additives such as other proteins (e.g., serum albumin), amino acids, and surfactants to minimize adsorption to surfaces. Modification of protein structure to enhance stability by genetic engineering may also be feasible, as well as chemical modification such as formation of a conjugate with polyethylene glycol. 

Sterility, freedom from pyrogens, and acceptably low level of extraneous particulate matter are critical quality attributes of all injectable products. Additional critical quality attributes depend on the clinical use of the product. For example, for IV, IM, and SC routes, isotonicity and physiological pH (7.4) are always desirable in order to minimize potential irritation upon injection. Other factors may preclude this, however. If the required dose of drug must be administered in a small volume, it may not be feasible to formulate an isotonic solution. Likewise, solubility or stability considerations may preclude formulation at physiological pH. This explains why formulation pH for injectable drugs varies from about pH 2 to about pH 11. 

Pharmaceutical scientists have developed improved suspension dosage forms to overcome problems of poor physical stability and patient-perceived discomfort attributed to some active ingredients. An important development aspect of any suspension is the ability to resuspend easily any settled particles prior to instillation in the eye and ensure that a uniform dose is delivered. It would be ideal to formulate a suspension that does not settle since the patient may not always follow the labeled instructions to shake well before using. However, this is usually not feasible or desirable since the viscosity required to retard settling of the insoluble particles completely would likely be excessive for a liquid eyedrop. The opposite extreme, of allowing complete settling between doses, usually leads to a dense layer of agglomerated particles that are difficult to resuspend. 

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