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Chemical Additives (chemical + additive)
Selected AbstractsLaser Spinning of Bioactive Glass NanofibersADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Félix Quintero Abstract The production of nanofibers of bioactive glass by laser spinning is reported. The technique yields a great quantity of free-standing fibers in the form of a mesh of disordered intertwined fibers. The method does not rely on chemical processing and does not need any chemical additive. It involves melting of a precursor material with tailored composition, which makes it possible to produce nanofibers from materials with which conventional melt drawing techniques cannot be used. Herein, the production of 45S5 Bioglass nanofibers is reported for the first time. The process is very fast (nanofibers of several centimeters are grown in a fraction of a second), without the necessity of post heat treatments, and no devitrification is observed as a result of the laser-spinning process. The morphology, composition, and structure of the nanofibers are characterized and an assessment of their bioactivity is carried out by immersion in simulated body fluid. This technique provides a method for the rapid production of dense glass nanofibers that can be employed as bioactive nanocomposite reinforcement, as a synthetic bone graft to replace missing bone, or to produce 3D structures for use as scaffolds for bone-tissue engineering. [source] A study on the conditioning effects of natural shampoos using the scanning electron microscope*INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2001J. Bellare Synopsis The scanning electron microscope (SEM) was successfully used to study the effects of toiletry treatment with shampoo on the microstructure of hair. This paper describes the use of SEM for comparing the conditioning effects of herbal shampoos. Commercially available herbal shampoos are not completely natural, but contain herbal extracts in a synthetic detergent base, along with other chemical additives. Completely natural shampoos were formulated in the laboratory and their conditioning effects were evaluated by comparing with a commercially available herbal shampoo. The micrographs were studied quantitatively using ,Image Analyser Software' and the extent to which the hair scales were uplifted was measured. The results obtained from the quantitative comparison were in agreement with those obtained from other tests, such as protein loss determination. The damage caused to the hair due to sodium lauryl sulphate was visible in the micrographs. The laboratory formulations were found to be better than the commercially available product. Thus, quantitative measurements from SEM micrographs are a valuable tool to compare the conditioning effects of hair care products. Résumé Le microscope electronique balayant (SEM) est appliqué avec succès a étudier les effets de traitments hygiéniques par shampooing sur le microstucture de cheveux. L'éxposé présent signale l'emploi de SEM a comparer l'effet conditionant des shampoing naturelle (herbacé). Les shampooing herbal de commerce ne sont pas totalement naturelle mais contient extrait de herbe medicinale melangés avec une base de détergent synthetique et d'autres produits chimiques; donc shampooing totalement naturelle a eté formulés dans laboratoire et leurs effets conditionant evalués en comparant avec shampooing herbal (naturelle) de commerce. Les micrographs étaient étudiés quantitativement utilisant ,Image Analyser Software' en mesurant le degré de relèvement de écailes des cheveux. Les résultats obtenues par comparison quantitative sont en accord avec ceux obtenues par d'autres éprevues comme perte de protéine. Le dommage causé aux cheveux par SLS est visible dans les micrographs. Les formulations de laboratoire étaient trouvés meilleurs en comparant avec les produits de commerce. Donc le measure quantitative des micrographs SEM est un outil valable a comparer les effets conditionant de produits hygienique pour cheveux. [source] Hydrothermal Synthesis of Alpha Alumina (,-Al2O3) Powders: Study of the Processing Variables and Growth MechanismsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2010Wojciech L. Suchanek Alpha alumina (,-Al2O3) powders and ,-Al2O3/boehmite (,-AlOOH) mixtures with controlled ,-AlOOH contents were synthesized hydrothermally under alkaline or acidic conditions at 380°,435°C for 1,10 days, under 6.9,14.5 MPa pressure, from concentrated precursors without stirring. The precursors were formed by mixing different types of aluminum hydroxides with water, and optionally with ,-Al2O3 seeds, hydrogen peroxide, sulfuric acid, dopants (i.e., KMnO4), and/or other additives. The experiments were performed on industrial scale in large production autoclaves. The synthesized ,-Al2O3 powders exhibited up to 100% phase purity, 99.98% chemical purity, equiaxed morphology, low aggregation levels, narrow crystallite size distributions with primary particle sizes ranging between 100 nm and 40 ,m, and high reproducibility. Precursor types, seeds, chemical additives, and temperature/time of the hydrothermal synthesis were found to govern properties of the powders. Different growth mechanisms for nanosized and rough powders are discussed. Results of this study enable the use of hydrothermal ,-Al2O3 powders in a multitude of applications, and make their hydrothermal production a commercial reality. [source] Stability of hydroperoxide lyase activity from Amaranthus tricolor (Amaranthus mangostanus L.) leaves: influence of selected additivesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2010Zhen Long Abstract BACKGROUND: Hydroperoxide lyase (HPL) has potential value for the flavour additive industry. Currently, the production and application of HPL suffer from stability problems. The objective of this study was to investigate the stabilisation of HPL preparation from Amaranthus tricolor leaves by the addition of selected chemical additives. RESULTS:Amaranthus tricolor leaves were identified as a particularly rich source of 13-HPL activity. The addition of 100 g L,1 sucrose and trehalose to microsomal HPL prior to lyophilisation could retain nearly 100% enzymatic activity, compared to only 20% for the lyophilised control. The lyophilised microsomal HPL containing sucrose maintained full activity for even 40 days storage at , 20 °C. For HPL solution, glycerol was effective for long-term stability at , 20 °C. Moreover, poyols (sucrose and trehalose) and amino acid (glycine) enhanced the thermostability of HPL, while KCl and polyol mannitol decreased the thermostability of HPL. CONCLUSION: The flavour-producing enzyme HPL, found in the leaves of Amaranthus tricolor, was stabilised by the addition of chemical additives. Copyright © 2010 Society of Chemical Industry [source] | ||||||||||