Search results for "gellan"
showing 10 items of 50 documents
Synthesis, Characterization and Sorption Capacity Examination for a Novel Hydrogel Composite Based on Gellan Gum and Graphene Oxide (GG/GO)
2020
A novel hydrogel composite based on gellan gum and graphene oxide (GG/GO) was synthesized, characterized and tested for sorption capacity in this work. The microstructural, thermogravimetric and spectroscopic analysis confirmed the formation of the GG/GO composite. Comparative batch sorption experiments revealed a sorption capacity of the GG/GO composite for Zn (II) ions of approximately 2.3 higher than that of pure GG. The GG/GO composite exhibits a maximum sorption capacity of 272.57 mg/g at a pH of Zn (II) initial solution of 6. Generally, the sorption capacity of the sorbents is approximately 1.5 higher in slightly acidic conditions (pH 6) comparative with that for strong acidic conditi…
Thixotropic Behavior of Salad Dressings Stabilized with Modified Starch, Pectin, and Gellan Gum. Influence of Temperature
2008
The thixotropy of low‐oil salad dressing has been analyzed at different temperatures (8–26°C). The usual formulation containing modified starch (4%) was compared with others in which part of the starch had been substituted by pectin (0.5%) or different concentrations of gellan (0.1 and 0.5%). Up and down flow curves were measured, showing in all cases shear thinning behavior and fitting the Herschel‐Bulkley model. Thixotropic areas enclosed by the up curve and the corresponding different down curves, STh, were obtained. With the aim of establishing comparative results, and since the viscosities were quite different, the parameter considered was relative thixotropic area, SR (%)=100 (STh/Sup…
Near-infrared light-responsive and antibacterial injectable hydrogels with antioxidant activity based on a Dopamine-functionalized Gellan Gum for wou…
2022
The development of wound dressings with combined antioxidant, antibacterial and tissue adhesion functions has been a difficult medical task for the treatment of wound infections. We synthetized a dopamine and PEG functionalized Gellan Gum (GG) to produce an injectable hydrogel with radical scavenging activity having both specific and aspecific antibiotic/antimicrobial properties. Using starting GG with different molecular weights, we obtained two derivatives that have been used to prepare the gel precursor dispersion, that undergoes gelation in the presence of colistin and dried microparticles (MPs) functionalized on the surface with polydopamine (pDA). Both were used to dope the hydrogel, …
The 30 Year Search for the Compact Object in SN 1987A
2018
Despite more than 30 years of searches, the compact object in Supernova (SN) 1987A has not yet been detected. We present new limits on the compact object in SN 1987A using millimeter, near-infrared, optical, ultraviolet, and X-ray observations from ALMA, VLT, HST, and Chandra. The limits are approximately 0.1 mJy ($0.1\times 10^{-26}$ erg s$^{-1}$ cm$^{-2}$ Hz$^{-1}$) at 213 GHz, 1 Lsun ($6\times 10^{-29}$ erg s$^{-1}$ cm$^{-2}$ Hz$^{-1}$) in optical if our line-of-sight is free of ejecta dust, and $10^{36}$ erg s$^{-1}$ ($2\times 10^{-30}$ erg s$^{-1}$ cm$^{-2}$ Hz$^{-1}$) in 2-10 keV X-rays. Our X-ray limits are an order of magnitude less constraining than previous limits because we use a…
Effect of chelatants on gellan gel rheological properties and setting temperature for immobilization of living bifidobacteria.
1993
The effect of various concentrations of sequestrants (sodium citrate, sodium metaphosphate, and EDTA) was studied on gellan gel (1.5-2.5% (w/v)) setting temperature and rheological properties. Addition of EDTA between 0 and 0.8% (w/v) led to a progressive decrease of setting temperature. Citrate and metaphosphate decreased this parameter when added up to 0.4 or 0.6%, depending on gellan gum concentration, eventually resulting in the absence of gel formation at room temperature for the 1.5% gellan solution containing 0.4% citrate. This effect was accompanied by a significant decrease of gel strength and stiffness and might be attributed to the binding of the divalent cations required for cha…
Interactions of different hydrocolloids with milk proteins
2020
Abstract To control rheological properties and accomplish perfect sensory properties and mouthfeel, polysaccharides are added to milk-based beverages. However, in contrast to expectations, it is often found that adding low concentrations of xanthan gum or guar gum to milk provokes phase separations of unclear physical origin. From this observation, questions arise regarding the interaction of added polysaccharides and the proteins present in milk – caseins and whey proteins. The focus of this study is to investigate such systems and to understand the basic interactions of caseins and whey proteins with different hydrocolloids. The hydrocolloids used in this study are xanthan gum, guar gum, …
Tetronciumand its only species,T. magellanicum(Juncaginaceae): distribution, ecology and lectotypification
2013
Abstract Mering S. von: Tetroncium and its only species, T. magellanicum (Juncaginaceae): distribution, ecology and lectotypification. — Willdenowia 43: 13–24. June 2013. — Online ISSN 1868–6397; © 2013 BGBM Berlin-Dahlem. Stable URL: http://dx.doi.org/10.3372/wi.43.43102 Tetroncium magellanicum (Juncaginaceae) was described by Willdenow in 1808, based on material collected by Commerson at the Strait of Magellan during Bougainville's voyage around the world. Type material of this species was traced and a lectotype for the name is designated. A description of the species and notes on its ecology and conservation status are provided. For the first time, a detailed map showing the known distri…
Post-AGB candidates in LMC and SMC SALT spectra
2020
We selected a sample of post-AGB candidates in the Magellanic Clouds on the basis of their near- and mid-infrared colour characteristics. Fifteen of the most optically bright post-AGB candidates were observed with the South African Large Telescope in order to determine their stellar parameters and thus to validate or discriminate their nature as post-AGB objects in the Magellanic Clouds. The spectral types of absorption-line objects were estimated according to the MK classification, and effective temperatures were obtained by means of stellar atmosphere modelling. Emission-line objects were classified on the basis of the fluxes of the emission lines and the presence of the continuum. Out of…
Pulsating B and Be stars in the Small Magellanic Cloud
2008
Context: Stellar pulsations in main-sequence B-type stars are driven by the kappa-mechanism due to the Fe-group opacity bump. The current models do not predict the presence of instability strips in the B spectral domain at very low metallicities. As the metallicity of the SMC is lower than Z=0.005, it constitutes a very suitable object to test these predictions. Aims: The main objective is to investigate the existence of B-type pulsators at low metallicities, searching for short-term periodic variability in absorption-line B and Be stars in the SMC. The analysis has been performed in a sample of 313 B and Be stars with fundamental astrophysical parameters accurately determined from high-res…
Stable carbon and oxygen isotope fractionation in bivalve (Placopecten magellanicus) larval aragonite
2008
Abstract The relationship between stable isotope composition (δ13C and δ18O) in seawater and in larval shell aragonite of the sea scallop, Placopecten magellanicus, was investigated in a controlled experiment to determine whether isotopes in larval shell aragonite can be used as a reliable proxy for environmental conditions. The linear relationship between δ13CDIC and δ13Caragonite (r2 = 0.97, p δ 13 C DIC = 1.15 ( ± 0.05 ) ∗ δ 13 C aragonite - 0.85 ( ± 0.04 ) The relationship between δ13CDIC and δ13Caragonite described for P. magellanicus resulted in larval shell aragonite that was depleted on average by 1.82‰ (SD = 0.22‰, range = 1.1–2.1‰) from predicted equilibrium values based on the r…