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Retention Ability (retention + ability)
Selected AbstractsExtrafloral nectar from cotton (Gossypium hirsutum) as a food source for parasitic waspsFUNCTIONAL ECOLOGY, Issue 1 2006U. S. R. RÖSE Summary 1For many adult nectar-feeding parasitoids food and moisture are essential for survival in the field. Early in the season, when floral nectar is not yet available in cotton, extrafloral nectar (EFN) is already present on young cotton plants. 2The parasitoid Microplitis croceipes (Cresson) can use EFN cotton plants as an only food source. The longevity and reproduction of EFN-fed female wasps was comparable to wasps fed with honey and water provided on nectariless (NL) cotton plants, and was significantly higher compared with wasps kept on NL plants with no additional food source. 3Wasps that were given preflight experiences on EFN cotton plants choose EFN cotton over NL cotton plants in two choice experiments in the flight tunnel. The parasitoids are more willing to search on an EFN plant at their second and third encounter with a plant previously visited, compared with an NL cotton plant. 4Wasps can locate EFN from short distances by its odour alone, and find it almost as fast as honey, but much faster than odourless sucrose, which is only found randomly. Experience with EFN increased the retention ability of parasitoids on a flower model. [source] Chitosan scaffolds for in vitro buffalo embryonic stem-like cell culture: An approach to tissue engineeringJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007Wah W. Thein-Han Abstract Three-dimensional (3D) porous chitosan scaffolds are attractive candidates for tissue engineering applications. Chitosan scaffolds of 70, 88, and 95% degree of deacetylation (% DD) with the same molecular weight were developed and their properties with buffalo embryonic stem-like (ES-like) cells were investigated in vitro. Scaffolds were fabricated by freezing and lyophilization. They showed open pore structure with interconnecting pores under scanning electron microscopy (SEM). Higher % DD chitosan scaffolds had greater mechanical strength, slower degradation rate, lower water uptake ability, but similar water retention ability, when compared to lower % DD chitosan. As a strategy to tissue engineering, buffalo ES-like cells were cultured on scaffolds for 28 days. It appeared that chitosan was cytocompatible and cells proliferated well on 88 and 95% DD scaffolds. In addition, the buffalo ES-like cells maintained their pluripotency during the culture period. Furthermore, the SEM and histological study showed that the polygonal buffalo ES-like cells proliferated well and attached to the pores. This study proved that 3D biodegradable highly deacetylated chitosan scaffolds are promising candidates for ES-like cell based tissue engineering and this chitosan scaffold and ES cell based system can be used as in vitro model for subsequent clinical applications. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] Combined effects of wetting, drying, and microcrystalline cellulose type on the mechanical strength and disintegration of pelletsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2009Maria Balaxi Abstract Effects of wetting and drying conditions on micromeritic, mechanical and disintegration properties of microcrystalline cellulose (MCC) pellets were evaluated. Extrusion/spheronization and three drying methods (fluidized bed, microwaves, and freeze drying) were applied using two wetting liquids (water or water-isopropanol 60:40 w/w) and three MCC types: (standard, silicified, and modified). Additionally, the effects of drying method were compared on highly porous pellets prepared by the incorporation and extraction of pore former (NaCl). It was found that the drying method has the greatest effect on the pellet size and porosity followed by the wetting liquid. The modification of MCC resulted in reduced water retention ability, implying hornification, increased porosity, reduced resistance to deformation and tensile strength of pellets. The disintegration time also decreased markedly due to the modification but only in the low porosity range <37%. Silicification increased greatly the disintegration time of the low porosity pellets (<14%). Combination of water-isopropanol, freeze drying and modified MCC gave the greatest increase in pellet size and porosity. The increase in pellet porosity caused exponential reduction in the resistance to deformation, tensile strength and disintegration time, as expected. Compared to fluidized bed, the freeze drying resulted in 20,30% higher porosity for pellets prepared without pore former and 6% for those with pore former, indicating the possibility of preparing highly porous pellets by employing freeze drying. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:676,689, 2009 [source] Regioselective Grafting of Poly(ethylene glycol) onto Chitosan and the Properties of the Resulting CopolymersMACROMOLECULAR BIOSCIENCE, Issue 10 2006Li Liu Abstract Summary: PEG was grafted onto chitosan regioselectively at the hydroxyl groups with phthaloylchitosan as an intermediate. After the graft reaction, the phthaloyl groups were deprotected to give chitosan- g -PEG copolymers with free amino groups. The chemical structure of the graft copolymers was confirmed by FT-IR, 1H and 13C NMR spectroscopy. The resulting graft copolymers showed improved thermal stability compared to the original chitosan, and showed a lower thermal transition temperature at around 185,°C. Chitosan- g -PEG exhibited a high affinity not only for aqueous acid but also for some organic solvents because of the presence of abundant free amino groups and PEG branches, and it exhibited higher hygroscopicity and moisture retention ability than chitosan. [source] Water absorption behavior of different types of organophilic montmorillonite-filled polyamide 6/polypropylene nanocompositesPOLYMER COMPOSITES, Issue 2 2010Kusmono The water absorption behavior of different types of organophilic montmorillonite (OMMT)-filled polyamide 6/polypropylene nanocomposites with and without compatibilizers (maleated PP or PP- g -MA and maleated styrene-ethylene/butylene-styrene or SEBS- g -MA) was evaluated. Four different types of OMMT, i.e., dodecylamine-modified MMT (D-MMT), 12 aminolauric acid-modified MMT (A-MMT), stearylamine-modified MMT (S-MMT), and commercial organo-MMT (C-MMT) were used as reinforcement. The water absorption response of the nanocomposites was studied and analyzed by tensile test and morphology assessment by scanning electron microscopy (SEM). The kinetics of water absorption of the nanocomposites conforms to Fick's law. The Mm and D are dependent on the types of OMMT and compatibilizers. The equilibrium water content and diffusivity of PA6/PP blend were increased by the addition of OMMT but decreased in the presence of compatibilizers. On water absorption, both strength and stiffness of the nanocomposites were drastically decreased, but the ductility was remarkably increased. Both PP- g -MA and SEBS- g -MA played an effective role as compatibilizers for the nanocomposites. This was manifested by their higher retention ability in strength and stiffness (in the wet and re-dried states), reduced the equilibrium water content, and diffusivity of the nanocomposites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Preparation, swelling behaviors and application of polyacrylamide/attapulgite superabsorbent compositesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 1 2006Junping Zhang Abstract A series of superabsorbent composites, polyacrylamide/attapulgite (PAMA), were prepared from acrylamide (AM) and attapulgite micropowder in aqueous solution, using N,N,-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator and then saponified with sodium hydroxide solution. This paper focuses on swelling behaviors of the PAMA superabsorbent composites in various saline solutions. The results indicate that saline solutions can weaken the swelling abilities of the PAMA compsites greatly. Water absorbency of the PAMA composites with 20 and 40,wt% attapulgite in aqueous chloride salt solutions has the following order: Li+,=,Na+,=,K+, Mg2+,>,Ca2+,=,Ba2+ all through the range of concentration investigated. However, swelling properties of the composites are complicated in CuCl2(aq), AlCl3(aq) and FeCl3(aq) solutions and are related to saline solutions concentration. The deswelling behavior of PAMA composites is more obvious in univalent chloride salt solutions than in divalent and trivalent ones. The influence of kind and valence of anions on swelling ability of the composites is limited and almost the same. Moreover, reswelling capability, practical water retention ability in sand soil of the composites and the effect of pH on water absorbency of the PAMA composites were investigated. The PAMA composite shows good water retention and reswelling ability in sand soil, and may be used as a recyclable water-managing material for the renewal of arid and desert environment. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||