Remo js Meri

A DSC study of the effect of ascorbic acid on bound water content and distribution in chitosan-enriched bread rolls during storage

Changes of tightly and loosely bound water relative content in bread were studied using differential scanning calorimetry method. Combination of chitosan with ascorbic acid changes water redistribution between starch and gluten and in such a way can be related to bread quality and sensory properties. The decrease of the water vaporization temperatures, melting temperatures and enthalpies in fresh bread containing chitosan were detected when ascorbic acid was added in combination with chitosan. The decrease of melting peak temperature has been attributed to the increase of interaction of loosely bound water and the decrease of vaporization peak temperature has been attributed to the decrease of interaction of tightly bound water with bread components as a result of ascorbic acid addition. Freezable water amount and total water amount in crumb decrease more rapidly during first stage of staling and more slowly at the second stage of staling in the bread nutritionally fortified with chitosan.

A DSC study of the effect of bread making methods on bound water content and redistribution in chitosan enriched bread

The effect of bread making methods on bound water migration from crumb to crust and moisture redistribution during bread storage at room temperature was studied. Comparative analysis of water behavior in bread crusts and crumbs was performed using differential scanning calorimetry method. Water vaporization enthalpies and temperatures of water vaporization peaks were determined and compared for bread produced by a single stage, straight dough method and bread produced by a two stage, sponge-and-dough method. The effect of chitosan on the crust and the crumb properties was analyzed for the breads produced by both methods.

The Use of Thermal Analysis in Assessing the Effect of Bound Water Content and Substrate Rigidity on Prevention of Platelet Adhesion

Implant surface-induced initiation of blood coagulation leading to thrombus formation is a major problem. It is an important challenge in biomedical research to enhance thromboresistance of polymer coatings of blood-contacting implants and devices by the reduction of platelet adhesion to their surfaces. Currently, the molecular mechanisms responsible for interfacial processes related to regulation of protein adsorption and platelet adhesion in antithrombotic coatings are not yet clearly understood. We studied the role of water binding energy in chitosan molecules using differential scanning calorimetry and thermogravimetric analysis and the role of chitosan coating rigidity using dynamic mechanical thermal analysis in the prevention of platelet adhesion. It was found that the presence of loosely bound water in chitosan coatings increases platelet adhesion. The high molecular weight (HMW) chitosan coating that contains only tightly bound water prevents platelet adhesion. The high molecular weight (HMW) chitosan coating is more rigid and has higher platelet adhesion compared with more soft LMW chitosan coatings. The degree of hydration of thromboresistant coatings is significant parameter that must be taken into account in the design of blood-contacting surfaces.

Metal oxide mineral filler containing polymer nanocomposites

Metal oxide mineral filled polycarbonate (PC) nanocomposites have been investigated. Plasma-chemical synthesis has been used to obtain metal oxide nanoparticles (MON). Melt mixing has been utilized to obtain PC/MON composites with regularly organized nanostructure. Consequently, an increasing in MON content caused a small decrease of surface and volume resistivities and an increase of nanocomposites magnetic activity.

Recycled Polycarbonate Based Nanocomposites

Post-consumer polycarbonate (RPC) blends with various amounts (5, 10, 30 wt. %) of ethylene vinyl acetate copolymer (EVAc) are investigated as potential nanocomposite matrices. At EVAc weight content of 10 wt.% maximum tensile strength σM and impact strength AI increase is observed in comparison to neat RPC. Addition of EVAc, however, reduces resistance to creep as well as decrease thermal stability of the investigated compositions. Addition of montmorillonite nanoclay (MMT), however, allows increase modulus of elasticity E and yield strength σY of the investigated RPC blend with 10 wt. % of EVAc. Besides it creep resistance and thermal resistance of the investigated system is increased to certain extent.

Characterisation of bare and tannase-loaded calcium alginate beads by microscopic, thermogravimetric, FTIR and XRD analyses

Incorporating enzymes into calcium alginate beads is an effective method to immobilise them and to preserve, at the same time, their catalytic activity. Sodium alginate was mixed with Aspergillus ficuum tannase in aqueous solution, and tannase-loaded calcium alginate beads were prepared using a simple droplet-based microfluidic system. Extensive experimental analysis was carried out to characterise the samples. Microscopic imaging revealed morphological differences between the surfaces of bare alginate matrix and tannase-loaded alginate beads. Thermal analysis allowed assessing the hydration contents of alginate and revealed the presence of tannase entrapped in the loaded beads, which was confirmed by vibrational spectroscopy. X-ray diffraction allowed us to conclude that alginate of tannase-loaded beads is not crystalline, which would make them suitable as carriers for possible controlled release. Moreover, they could be used in food applications to improve tea quality or clarify juices.

Bionanocomposites poly(ϵ-caprolactone)/organomodified Moroccan beidellite clay prepared by in situ ring opening polymerization: Characterizations and properties

ABSTRACT In this study, a series of poly(ϵ-caprolactone) (PCL)/clay bionanocomposites were prepared via in situ ring opening polymerization (ROP) of ϵ-caprolactone catalyzed by titanium butoxide. The natural Moroccan clay beidellite (BDT), used as nanocharge, was organomodified with cetyltrimethylammonium bromide, CTA, to obtain the organically modified 3CTA-BDT (3 = CTA/BDT equivalent feed ratio). Characteristics of the final nanocomposites are investigated by FTIR, SEC, XRD, SEM, TGA, DSC, optical tensiometry, thermal conductivity and water vapor sorption analysis. The intercalated/exfoliated morphologies, revealed by XRD and SEM analyses, confirm uniform dispersion of the nanoclay within the PCL matrix. Thermal stability of all the nanocomposites is improved by the addition of 3CTA-BDT clay compared to pure PCL polymer. The DSC data show that the addition of 3CTA-BDT particles promotes an increase in the disorder of the crystalline phase, which reduces the crystallinity degree. The hydrophobicity of Polymer/clay compatibility was analyzed by studying surface polarity degree of samples by contact angle measurements. Thermal conductivity and water vapor sorption was also discussed. The permeability (P), the sorption coefficient (S) and the diffusion coefficient (D), showed a significant decrease with increasing 3CTA-BDT loading.

Compatibilizers Effect on Silyl-Terminated Polyether/Epoxy Resin System Mechanical and Rheological Properties

In this work we study influence of compatibilizers on tensile and rheological properties of new Silyl terminated polymer/Epoxy two component systems. In early works about that kind systems most of attention is devoted to polymers used (mainly silyl terminated polyether), while less attention is paid to catalysts, compatibilizers and additives [1-2]. One of the most important system elements are compatibilizers, while in this particular system silyl terminated polyether cannot react with epoxy groups directly. This work indicates that compatibilizer has a crucial meaning to reach material potential mechanical properties.

PC/ ABS Nanocomposites with Layered Silicates : Obtaining, Structure and Properties

Due it increasing use in electronics, polymers, mainly acrylonitrile-butadiene-styrene (ABS) and its blend with polycarbonate (PC), are making considerable part of electronic waste. It has been proven that halogenated flame retardants used in polymers for electronics are toxic to environment and human health. Aim of the research is to evaluate the effects of nanostructured montmorillonite clay (D43B) addition on the mechanical and thermal characteristics of PC, ABS and its binary blends. The effect of substitution of virgin polymers in the blend with recycled ones has been also investigated. It has been determined that as far as the recycled polymer content in the composites does not exceed 10wt.%, tensile and thermal properties of the systems are not considerably affected. Addition of D43B up to 1,0-1,5wt.% contributes to the increment of mechanical stiffness, strength and thermal stability of the composites.

Structural characterization of cevimeline and its trans-impurity by single crystal XRD.

Cevimeline is muscarinic receptor agonist which increases secretion of exocrine glands. Cevimeline base is a liquid (m.p. 20-25 °C) at ambient conditions, therefore its pharmaceutical formulation as a solid hydrochloride hemihydrate has been developed. The synthesis of cevimeline yields its cis- and trans-isomers and only the cis-isomer is recognized as the API and used in the finished formulation. In this study structural and physicochemical investigations of hydrochloride hemihydrates of cis- and trans-cevimelines have been performed. Single crystal X-ray analyses of both cis- and trans-isomers of cevimeline are reported here for the first time. It was found that the cis-isomer, the API, has less dense crystal packing, lower melting point and higher solubility in comparison to the trans-isomer.