A Facile and Efficient Bromination of Multi-Walled Carbon Nanotubes.

The bromination of multi-walled carbon nanotubes (MWCNT) was performed with vapor bromine in a closed vessel, and they were subjected to intensive stirring with a magnetic stirrer for up to 14 days. The efficiency of bromination was compared depending upon duration. The structure and surface of the crude and purified products were characterized by detailed physicochemical analyses, such as SEM/EDS, TEM, XRD, TGA, Raman, and XPS spectroscopies.

Molecular Analysis of Retrogradation of Corn Starches.

Changes of the molecular dynamics of water in 5% corn starch pastes and 5% systems composed of starch and non-starchy hydrocolloid were studied during short and long term retrogradation. Low Field NMR was used to record mean correlation times (τ) of water molecules. This molecular parameter reflects the rotation of water molecules within the network of paste.

Short- and long-term retrogradation of potato starches with varying amylose content.

Background: Gels of potato starches with varying amylose content were prepared and the degree of pasting and the course of retrogradation were studied. The average molar masses of granular and pasted starches were estimated. Determination of the degree of pasting involved use of optical microscopy and the study of pasting characteristics.

Starch-metal complexes and metal compounds.

Recently, metal derivatives of starch evoked considerable interest. Such metal derivatives can take a form of starch compounds bearing metal atoms and metal carrying moieties either covalently bound or complexed. Starch metal complexes may have a character of either Werner, inclusion, sorption or capillary complexes.

Thixotropic properties of waxy potato starch depending on the degree of the granules pasting.

This paper presents the rheological instability (thixotropy/antithixotropy) of waxy potato starch (WPS) pastes depending on their concentration (1-5% w/w) and pasting temperature (80, 95 and autoclaved: 121°C, at 0.1MPa). The hysteresis loop, apparent viscosity at constant shear rate as well as the in-shear structural recovery tests with and without pre-shearing were applied.

Effect of the external electric field on selected tripeptides.

The effect of external electric field (EEF) of 5.14, 25.70, and 51.

Thixotropic properties of normal potato starch depending on the degree of the granules pasting.

The aim of this paper was the study of the rheological instability (thixotropy and/or antithixotropy) of normal potato starch (NPS) pastes depending on their concentration (2-5%) and degree of pasting. Flow curves with hysteresis loops, apparent viscosity at constant shear rate and in-shear structural recovery tests were carried out. Granule size profiles, the pasting characteristic of corresponding starch suspensions and the transmittance of the pastes, the molecular weights and polydispersity of granular starch and its pastes prepared at 80, 95 and 121°C were also studied.

Formation of nanometal particles in the dialdehyde starch matrix.

Environmentally friendly method of the preparation of dialdehyde starch (DAS) based composites containing nanosilver (DAS/Ag) and nanogold (DAS/Au) as reducing and protecting agents was developed. UV-vis spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirmed formation of about 10nm ball shaped Ag and Au nanoparticles situated within the polysaccharide template. Thermal properties of the composites were characterized involving differential scanning calorimetry (DSC), whereas molecular weights of polysaccharide chains of the matrix were estimated with the size exclusion chromatography coupled with multiangle laser light scattering and refractometric detectors (HPSEC-MALLS-RI).

Enzymatic conversions of starch.

This article surveys methods for the enzymatic conversion of starch, involving hydrolases and nonhydrolyzing enzymes, as well as the role of microorganisms producing such enzymes. The sources of the most common enzymes are listed. These starch conversions are also presented in relation to their applications in the food, pharmaceutical, pulp, textile, and other branches of industry.

Novel drug-loaded gelatin films and their sustained-release performance.

A new particulate drug delivery system with gelatin matrix containing Ibuprofen as a model drug molecule was developed for an epidermis drug prolonged release. Gelatin films containing Ibuprofen-loaded poly-epsilon-caprolactone (PCL) microspheres have been developed on evaporation of organic solvent from an oil-in-water emulsion followed by cross-linking. The microspheres were characterized for particle size, encapsulation efficiency, and surface morphology.

Formation of cyclodextrins with cyclodextrin glucosyltransferase stimulated with polarized light.

After illumination with white, linearly polarized light (WLPL), cyclodextrin glycosyltransferase produced mixture of alpha-, beta-, and gamma-cyclodextrins (CD) with higher overall yield than did that enzyme when nonilluminated. The illumination also influenced the ratio of those CD and that effect depended on concentration of enzyme and illumination time. At a high enzyme concentration (0.

Polarized light-stimulated enzymatic hydrolysis of chitin and chitosan.

Illumination with white linearly polarized light (WLPL) stimulated chitinase and chitosanase in their degradation of chitin and chitosan, respectively. Enzymes were illuminated at room temperature in separate vessels, then admixed in reactors containing polysaccharides. Hydrolysis of chitosan to glucosamine followed first order kinetics whereas hydrolysis of chitin to N-acetylglucosamine deviated from the first order kinetics.

Novel biodegradable blend matrices for controlled drug release.

Phosphorylcholine-functionalized poly-epsilon-caprolactone (PC-PCL) is a new biodegradable polymer with good biocompatibility. In this study modulation of the controlled release of Ibuprofen (IB), a model drug, from poly-epsilon-caprolactone (PCL) by direct blending with PC-PCL is investigated. The influence of several factors such as the content of PC-PCL in the blend, drug loading and the molecular weight of PCL matrix upon the IB release is recognized.

Non-covalent functionalization of multi-walled carbon nanotubes with organic aromatic compounds.

Several aromatic compounds derived from benzene by its annelation (naphthalene, anthracene, phenanthrene, pyrene) and exocyclic substitution (e.g., nitrobenzene, dinitrobenzenes, trinitrobenzene, chlorobenzene, N,N-dimethylaniline, and others) and endocyclic substitution (pyridine, quinoline, isoquinoline) efficiently sorbed on multi-walled carbon nanotubes (MWCNTs).

Complexes of 3.6 kDa maltodextrin with some metals.

Preparation of magnesium, lanthanum, and bismuth(III) complexes of 3.6 kDa maltodextrin and some properties of the resulting materials are presented. The metal derivatives contain metals bound to the oxygen atoms of the hydroxyl groups of maltodextrin.

Polymeric complexes of cornstarch and waxy cornstarch phosphates with milk casein and their performance as biodegradable materials.

Complexes of phosphated cornstarch and waxy cornstarch with casein were prepared and characterised. They were prepared from casein in defatted milk and corn and waxy corn starches phosphated to degree of substitution values (DS) of 0.0637 and 0.

Complexes of carbon nanotubes with selected carotenoids.

As proven by the UV-VIS, micro-Raman spectroscopies, differential scanning calorimetry, beta-carotene, lycopene, retinoic acid, and retinol adsorbed on the surface of single-walled carbon nanotubes (SWCNT) form electron donor-acceptor (EDA) complexes. The rate of the adsorption of carotenoids is estimated as the rate of decrease in their concentration in solution followed the exponential curve equation. The rate of the adsorption decreased with the chain length of the guest capable sorption on the surface and steric effect of the terminals in the beta-carotene was also essential.

Interactions of single-walled carbon nanotubes with monosaccharides.

Closed-end single-walled carbon nanotubes were wetted in aqueous solutions of monosaccharides, forming weak surface complexes, as proven by the estimation of the content of monosaccharides in complexes isolated from aqueous solutions. The complexation was confirmed by micro-Raman spectroscopy. The Gaussian 03 (Molecular Mechanics UFF method) computations of total energy of the single-walled carbon nanotube-monosaccharides inclusion and surface complexes showed that inclusion complexes should be more stable than corresponding surface complexes.

Complexes of amylose and amylopectins with multivalent metal salts.

Metal cations [Cu(II), Fe(III), Mn(II), and Ni(II)] are ligated by amylose as well as potato, and corn amylopectins as proven by electron paramagnetic resonance spectra and conductivity measurements. The hydroxyl groups of polysaccharides are the coordination sites. Isolated starch polysaccharides did not coordinate to metal ions so well as starch did.

Quantum-chemical model evaluations of thermodynamics and kinetics of oxygen atom additions to narrow nanotubes.

This paper reports a computational study of oxygen additions to narrow nanotubes, a problem frequently studied with fullerenes. In fact, fullerene oxides were the first observed fullerene derivatives, and they have naturally attracted the attention of both experiment and theory. C60O had represented a long-standing case of experiment-theory disagreement, and there has been a similar problem with C60O2.