Static stiffness coefficients for circular foundations embedded in an elastic medium.

Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Civil Engineering.Bibliography: leaves 105-111.M.S

Preparation of Emulsion Polymerization from Styrene Vinylpyrrolidone and Studying their Thermal Stability and Electrical Conductivity

Copolymer styrene and vinylpyrrolidone were prepared using different techniques. The emulsion polymerization technique was chosen as it gives the highest molecular weight with polymer particles in the nanorange. The polymer nanocomposites were prepared using Pickering emulsion polymerization stabilized by adding inorganic nanosized particles. Ag nanometal and nanometal oxides of CuO, ZnO and AgO were added into the copolymer for enhancing its thermal stability and electrical conductivity. The nanocomposite chemical structure was confirmed by using FTIR, 1HNMR spectroscopy and TEM. Transmission electron microscopy, TEM photos show that the copolymer particles are almost in the nanoscale region. The thermal stability (TGA) of styrene-co-vinylpyrrolidone in the presence of the nanometal and nanometal oxides was slightly increased. The electrical conductivity of these nanocomposites using dc at different temperatures was measured. The data reveal that the nanocomposites are enhanced by adding the nanometal and nanometal oxides. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3556

Antimicrobial properties of chitosan and galactomannan composite coatings and physical properties of films made thereof

The aim of this study was to produce antimicrobial coatings and films based on the mixture of chitosan and galactomannan from Adenanthera pavonina L., with the incorporation of sodium acetate. The antimicrobial activity of the coatings was evaluated against L. monocytogenes, S. aureus, P. aeruginosa and S. enteritidis. Then the films produced, based on the coating formulations, were characterized in terms of water vapour permeability (WVP), oxygen (O2) and carbon dioxide (CO2) permeability, moisture content (MC), water solubility (S), tensile strength (TS), elongation at break (EB), elastic modulus (EM), opacity and color. The composite coatings with Chi were effective against Gram-negative and Gram-positive bacteria. Films Chi presented the low water solubility and high values of component b*, which indicates the predominance of yellowish coloration and the highest TS values. Films of Chi-Gal-NaA present lower values of S, MC, WVP and EB and is the film presenting the higher value of EM. While for the films of Gal-NaA there was a reduction of the O2 permeability and an increase of CO2 permeability. Chi in combination with NaA can be used in the development of antimicrobial coatings and films for food applications, therefore contributing to food preservation and shelf-life extension.CNPq -Conselho Nacional de Desenvolvimento Científico e Tecnológico(undefined)info:eu-repo/semantics/publishedVersio

Active edible films: Current state and future trends

Active edible films represent one of the current and future trends in the development of new polymers for selected applications, particularly food packaging. Some biopolymers show excellent performance as carriers for active compounds extracted from natural sources and are able to be released at a controlled rate to packaged food. In this review we aim to present, in a comprehensive way, the most recent advances and updates in this subject, where much research is currently ongoing and new studies are reported very often. This review focuses on innovative biopolymer matrices, their processing to obtain edible active films, and present and future applications

Chitin-based Materials in Tissue Engineering: Applications in Soft Tissue and Epithelial Organ

Chitin-based materials and their derivatives are receiving increased attention in tissue engineering because of their unique and appealing biological properties. In this review, we summarize the biomedical potential of chitin-based materials, specifically focusing on chitosan, in tissue engineering approaches for epithelial and soft tissues. Both types of tissues play an important role in supporting anatomical structures and physiological functions. Because of the attractive features of chitin-based materials, many characteristics beneficial to tissue regeneration including the preservation of cellular phenotype, binding and enhancement of bioactive factors, control of gene expression, and synthesis and deposition of tissue-specific extracellular matrix are well-regulated by chitin-based scaffolds. These scaffolds can be used in repairing body surface linings, reconstructing tissue structures, regenerating connective tissue, and supporting nerve and vascular growth and connection. The novel use of these scaffolds in promoting the regeneration of various tissues originating from the epithelium and soft tissue demonstrates that these chitin-based materials have versatile properties and functionality and serve as promising substrates for a great number of future applications

Thermal analysis of chiral drug mixtures: the DSC behavior of mixtures of ephedrine HCl and pseudoephedrine HCl enantiomers

A method for peak shape analysis and deconvolution of overlapping endotherms in differential scanning calorimetry (DSC) data has been previously reported. In this study the method is applied to binary mixtures of, (i) (1S,2S)-(+)- and (1R,2R)-(-)-ψ-ephedrine HCl, and (ii) (1S,2S)-(+)-ψ-ephedrine HCl and its diastereomer, (1S,2R)-(+)-ephedrine HCl. Phase diagrams based on enthalpies of fusion at the melting point (ΔH ) as a function of mol% composition are linear. However, the phase diagrams based on melting temperature as a function of mol% composition are non-linear and show deviations from the theoretical Prigogine-Defay and Schröder-van Laar equations. Estimates of eutectic compositions are more definitive from the diagrams based on ΔH values. The phase diagram for the ψ-ephedrine HCl enantiomers demonstrates racemic compound formation with eutectic points for the compound and the pure enantiomers at 28.1 ± 2.5 mol% and 71.9 ± 2.5 mol%. The ΔH phase diagram for mixtures of (1S,2R)-(+)-ephedrine HCl and (1S,2S)-(+)-ψ-ephedrine HCl suggested the formation of a weak complex with a composition close to 60 mol% of the (1S,2S)-(+)-isomer