Dissolution of polystyrene into cyclic monoterpenes present in tree essential oils

We examined dissolution of polystyrene (PS) into cyclic monoterpenes present in tree essential oils, in order to develop an environmentally friendly shrinking agent for expanded polystyrene. The relationship between the chemical structure of the monoterpenes and their dissolution power for PS was studied through the solubility parameter (δ) and apparent activation energy (E _a) for dissolution. (R)-Limonene and its structural isomers on a C=C bond have high solvent power for PS. This favorable solubility was explained by their solubility parameters. The occurrence of hydroxyl group in a solvent molecule, such as in terpinen-4-ol, reduced affinity for PS. Bicyclic monoterpenes and 1,8-cineole, which have sterically bulky structure, showed limited dissolution power even though they have solubility parameters similar to that of (R)-limonene. Their bulky structures would interfere with permeation of solvent into the PS matrix. Cyclic monoterpenes and PS were recovered almost quantitatively by simple steam distillation of the PS solution.     

Prenatal diagnosis of atelosteogenesis type I at 21 weeks' gestation

We describe prenatal diagnosis in a male fetus at 21 weeks of gestation with atelosteogenesis type I (AO I). Fetal ultrasonography (US) revealed absent or deficient ossification of the posterior neural arches of the thoracic spine, humeri, radii, ulnae, fibulae, and short tubular bones other than the distal phalanges, in addition to extremely short, thick femora. Fetal magnetic resonance imaging (MRI) using an ultrafast imaging sequence depicted dysmorphic features, pulmonary hypoplasia, and large cisterna magna. Postmortem radiographs warranted a diagnosis of AO I. Autopsy corroborated not only pulmonary hypoplasia but also laryngeal stenosis. The chondro-osseous histological findings were consistent with those of AO I. Meticulous evaluation using fetal US and MRI permits a definitive prenatal diagnosis of AO I to be made. Copyright © 2002 John Wiley & Sons, Ltd.     

Studies on the pyrolysis behavior of gasification and melting systems for municipal solid waste

 It is important to investigate the pyrolysis processes of municipal solid waste (MSW) in the same way as for any mixture comprised of multiple substances. In this article, a two-reaction model for a variety of MSW mixtures is proposed to predict mass changes due to pyrolysis. In order to formulate the model based on pyrolysis kinetics, we conducted experiments to determine the kinetic model parameters. By thermal analysis of the typical components of MSW, mass changes attributable to the pyrolysis reaction were found at about 350°C for paper, 400°–500°C for plastics, and 200°–400°C for garbage (dry condition). Activation energies were obtained by the Ozawa method based on the mass changes in pyrolysis. Thus, the pyrolysis behavior is formulated as a function of temperature. Then the pyrolysis mass change of the mixture can be predicted by using a weighted sum of the individual components. The model proved useful in experiments with real waste (refuse-derived fuels). Furthermore, the weight yields (pyrolysis gas, tars, solid residues) of the mixture can be calculated by their additive property after measuring the mass balance of each component. Received: May 11, 2001 / Accepted: November 16, 2001