Relevance of Rheological Properties of Sodium Alginate in Solution to Calcium Alginate Gel Properties

Abstract. The purpose of this study is to determine whether sodium alginate solutions' rheological parameters are meaningful relative to sodium alginate's use in the formulation of calcium alginate gels. Calcium alginate gels were prepared from six different grades of sodium alginate (FMC Biopolymer), one of which was available in ten batches. Cylindrical gel samples were prepared from each of the gels and subjected to compression to fracture on an Instron Universal Testing Machine, equipped with a 1-kN load cell, at a cross-head speed of 120 mm/min. Among the grades with similar % G, (grades 1, 3, and 4), there is a significant correlation between deformation work (L E ) and apparent viscosity (η app ). However, the results for the partial correlation analysis for all six grades of sodium alginate show that L E is significantly correlated with % G, but not with the rheological properties of the sodium alginate solutions. Studies of the ten batches of one grade of sodium alginate show that η app of their solutions did not correlate with L E while tan δ was significantly, but minimally, correlated to L E . These results suggest that other factors-polydispersity and the randomness of guluronic acid sequencing-are likely to influence the mechanical properties of the resultant gels. In summary, the rheological properties of solutions for different grades of sodium alginate are not indicative of the resultant gel properties. Interbatch differences in the rheological behavior for one specific grade of sodium alginate were insufficient to predict the corresponding calcium alginate gel's mechanical properties

Evaluation of the utility of the Ponseti method of correction of clubfoot deformity in a developing nation

Clubfoot is the commonest congenital deformity in babies. More than 100,000 babies are born worldwide each year with congenital clubfoot. Around 80% of the cases occur in developing nations. We treated 154 feet [mean Pirani score (total) 5.57] in 96 children (78 males, 18 females) by the Ponseti method from January 2003 to December 2005. A prospective follow-up for a mean duration of 19.5 months (range 6–32 months) was undertaken. After six months of treatment the Pirani score was reduced to zero for all patients. The results show that corrective surgery, sometimes multiple, can be avoided in most cases which are usually associated with the development of a stiff, painful foot. Low socio-economic status and illiteracy prevailing in developing nations increases the prevalence of neglected clubfoot that is still harder to correct. Integration into various programs and proper use of available resources can decrease neglected clubfoot and improve chances of successful and timely correction of deformity. Bracing constitutes an important part of treatment and proper motivation and education of the parents mitigates the chances of losing correction. The Ponseti method of correcting clubfoot is especially important in developing countries, where operative facilities are not available in the remote areas and well-trained physicians and personnel can manage the cases effectively with cast treatment only

Relevance of Rheological Properties of Sodium Alginate in Solution to Calcium Alginate Gel Properties

The purpose of this study is to determine whether sodium alginate solutions’ rheological parameters are meaningful relative to sodium alginate’s use in the formulation of calcium alginate gels. Calcium alginate gels were prepared from six different grades of sodium alginate (FMC Biopolymer), one of which was available in ten batches. Cylindrical gel samples were prepared from each of the gels and subjected to compression to fracture on an Instron Universal Testing Machine, equipped with a 1-kN load cell, at a cross-head speed of 120 mm/min. Among the grades with similar % G, (grades 1, 3, and 4), there is a significant correlation between deformation work (LE) and apparent viscosity (ηapp). However, the results for the partial correlation analysis for all six grades of sodium alginate show that LE is significantly correlated with % G, but not with the rheological properties of the sodium alginate solutions. Studies of the ten batches of one grade of sodium alginate show that ηapp of their solutions did not correlate with LE while tan δ was significantly, but minimally, correlated to LE. These results suggest that other factors—polydispersity and the randomness of guluronic acid sequencing—are likely to influence the mechanical properties of the resultant gels. In summary, the rheological properties of solutions for different grades of sodium alginate are not indicative of the resultant gel properties. Inter-batch differences in the rheological behavior for one specific grade of sodium alginate were insufficient to predict the corresponding calcium alginate gel’s mechanical properties