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This paper describes a new technique to analyze processes with a positive change in the Gibbs free energy, ΔG, based on the second law of thermodynamics. In particular, the application of a two-stage process, consisting of an endothermic high-temperature first stage and an exothermic low-temperature second stage, has been investigated. This paper considers chemical reaction processes as heat engines and that by the appropriate flow of heat at a specific temperature (and, hence, with a specified exergy level) work can be added or removed from a process. The technique also investigates the integration of such processes in terms of work flows. The technique is useful in the early stages of the design process as well as for retrofitting. It helps identify opportunities and set targets for the process. The method does not require detailed information regarding the process and is based only on thermodynamic properties of the system.

The attainable region (AR) concept uses a geometrical procedure to determine the boundaries of the region that include all possible reactor products for a known feed condition. The procedure also allows the choice of reactor(s) and the sequencing of these reactors to maximize the selection of reactor products in terms of predefined objective functions. It is also possible to derive the process operating conditions commensurate with an optimum objective function. The AR concept currently is being applied to industrial applications, and in this paper the concept is used to study the manufacture of butadiene by the oxidative dehydrogenation of 1-butene. Process operating conditions, specifically the partial pressure of oxygen, are reviewed. The reactors discussed in this paper are the fixed-bed reactor and the inert porous membrane reactor. A candidate AR for the system butene−butadiene is proposed.

Hyperadrenocorticism causes obesity and enlargement of the islets of the pancreas due to hypertrophy and hyperplasia of the beta cells, suggesting accelerated release of insulin. It seems unlikely that an excess of circulating corticosteroids can produce obesity directly, since administration of corticosteroids which induces adiposity in control animals, fails to do so in mildly alloxan diabetic animals. Considerable reduction of the food intake does not prevent the increased fat deposition and islet hypertrophy in hyperadrenocorticism. Some strains of mice develop adiposity spontaneously and simultaneously show subcapsular adrenocortical hypertrophy and enlargement of the islets. All these changes can be prevented by adrenalectomy. Adrenalectomy, however, does not affect development of hypothalamic obesity. The obesity seen after castration in animals of suitable species and strains is also associated with hypertrophy of the adrenal cortex and the islets of the pancreas.It is thought that reduction or cessation of the activity of the gonads induces changes in the secretion of the adrenal cortex. This in turn stimulates increased secretion of insulin which produces adiposity.

Spontaneous diabetes mellitus was observed in a rat after injury to the ventromedial hypothalamus. At the time the diabetes was discovered, the animal was extremely obese. Fasting blood glucose was approximately 200 mg/100 ml, daily urinary glucose varied from 12 to 18 g, urinary volume from 280 to 370 ml. The islets of the pancreas showed no pathological changes. The adrenals weighed 108 mg vs. 58 mg control weight. Extensive infected skin lesions were present. The literature concerning diabetes after experimental hypothalamic injury is briefly reviewed.