Inverse gas chromatography applications: a review.

Inverse gas chromatography (IGC) is a versatile, powerful, sensitive and relatively fast technique for characterizing the physicochemical properties of materials. Due to its applicability in determining surface properties of solids in any form such as films, fibres and powders of both crystalline and amorphous structures, IGC became a popular technique for surface characterization, used extensively soon after its development. One of the most appealing features of IGC that led to its popularity among analytical scientists in early years was its similarity in principle to analytical gas chromatography (GC). The main aspect which distinguishes IGC experiments from conventional GC is the role of mobile and stationary phases. Contrary to conventional GC, the material under investigation is placed in the chromatographic column and a known probe vapour is used to provide information on the surface. In this review, information concerning the history, instrumentation and applications is discussed. Examples of the many experiments developed for IGC method are selected and described. Materials that have been analysed include polymers, pharmaceuticals, minerals, surfactants, and nanomaterials. The properties that can be determined using the IGC technique include enthalpy and entropy of sorption, surface energy (dispersive and specific components), work of co/adhesion, miscibility and solubility parameters, surface heterogeneity, glass transition temperature, and specific surface area.

Hyperthyroid vs hypothyroid eye disease: the same severity and activity.

PURPOSE: To compare demographics, severity, and activity of thyroid eye disease (TED) in patients with hyperthyroidism (Hr-TED) vs primary hypothyroidism (Ho-TED). PATIENTS AND METHODS: In a cross-sectional study, demographics, complete eye examination, severity score (NOSPECS, total hundred eye score), clinical activity score, and Rundle grading were recorded for patients with TED and different thyroid disorders referred from an endocrinology clinic from 2003 to 2006. RESULTS: TED was clinically found in 303 patients (303/851, 35.6%). The majority of them (280/303, 92.4%) had Graves' hyperthyroidism and 23 (23/303, 7.5%) had primary hypothyroidism. Mean age, gender, mean severity score, mean activity score, Rundle grade, unilateral presentation of TED, smoking habit, mean duration of eye disease, and mean interval time of thyroid to TED were not significantly different between the two groups (0.06