Recebido em 6/3/03; aceito em 28/4/03 EDTA: THE CHELATING AGENT UNDER ENVIRONMENTAL SCRUTINY. The chelating agent EDTA (ethylenediaminetetraacetic acid) is a compound of massive use world wide with household and industrial applications, being one of the anthropogenic compounds with highest concentrations in inland European waters. In this review, the applications of EDTA and its behavior once it has been released into the environment are described. At a laboratory scale, degradation of EDTA has been achieved; however, in natural environments studies detect poor biodegradability. It is concluded that EDTA behaves as a persistent substance in the environment and that its contribution to heavy metals bioavailability and remobilization processes in the environment is a major concern.

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In the final process of the bleached kraft pulp there are some cellulose fibers that are separated from the main fibers stream; these fibers are rejected and considered as a low quality fibers, these fibers are known as rejected fiber (RF). In the present work the potential use of these fibers for Cellulose Nanocrystals (CNCs) synthesis was studied. The physical and chemical properties of synthesized CNCs were characterized through different techniques such as Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Thermogravimetric Analysis (TGA). Results demonstrate the feasibility of CNCs synthesis with a yield of 28.1% and 36.9%, and crystallinity of 73.5% and 82.7%. Finally, the morphology and synthesis conditions suggest that this industrial reject fiber (RF) could be used as a source for the CNCs production, thus adding value to the kraft process and opening new possibilities for innovation in the pulp industry.

A surface treatment of metallic samples irradiated by a nitrogen ion beam generated in a co-axial plasma gun is presented. By placing a titanium insert at the end of the inner electrode of the device, a TiN coating was produced on the surface of the sample. X-ray diffraction, scanning electron microscopy, electron probe x-ray micro-analysis and x-ray photoelectron speectroscopy were employed to study the surface of the treated sample. It was found that the main role of the ion beam was to produce a strong pre-heating of the superficial layers of the substrate, thus favouring the diffusion of the impinging particles.

del Libenador 8250, 1429 Buenos Aires and CIC, Pmvincia de Buenos Aim, Argentina Abstrad Oxidation of pure titanium was carried out at mom temperahlre under different oxygen pressures (10-8-10d torr). The kinetics for each pressure was determined. Measured film thicknesses were larger for higher pressures. Deconvolution of m spectra showed mat 'EO was the major oxide present and TI& the minor component. Formation of T i 2 a and Ti305 was also observed.

Hydrogels of TEMPO-oxidized nanocellulose (TO-CNF) were stabilized for dry-jet wet spinning using a shell of cellulose dissolved in 1,5-diazabicyclo[4.3.0]non-5-enium propionate ([DBNH][CO2Et]), a protic ionic liquid (PIL). Coagulation in an acidic water bath resulted in continuous core-shell filaments (CSF) that were tough and flexible: average dry (and wet) toughness of ~11 (2) MJ . m -3 and elongation of ~9 ( 14) %. CSF morphology, chemical composition, thermal stability, crystallinity, and bacterial activity were assessed using scanning electron microscopy with energy dispersive X-ray spectroscopy, liquid-state nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, pyrolysis gas chromatography-mass spectrometry, wide angle X-ray scattering and bacterial cell culturing, respectively. The coaxial wet spinning yields PIL-free systems carrying on the surface the cellulose II polymorph, which not only enhances the toughness of the filaments but facilities their functionalization.apply a strategy based on the principles of the circular economy. Bio-based materials and, in particular, cellulose nanomaterials (CNMs) have become excellent candidates in this regard, as they could partially replace materials based on non-renewable resources. Indeed, CNMs enable high-performance, green functional materials with a broad spectrum of applications, e.g., electronics, biomedical and tissue engineering scaffolds, coatings, food, textiles, and even in daily use goods [1][2][3][4][5][6][7][8] .Cellulose resources have the potential of becoming a platform to develop novel CNMs with high mechanical performance since nanocellulose, in its cellulose I crystalline phase, possess an elastic modulus of about 150 GPa and 18-50GPa in the longitudinal and transverse directions, respectively 9,10 . The regioselective C6 oxidation of nanocellulose fibers can be additionally catalyzed by the use of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) nitroxyl radical to produce hydrogels with high transparency 11 , an extensive degree of fibrillation 12 , and low cytotoxicity 13 . These TEMPO-oxidized cellulose nanofibers (TO-CNF) are suitable for applications in diverse fields such as packaging 3,4,[14][15][16] , textiles [17][18][19][20] , biosensing and bioelectronics 21,22 , fire retardancy 23 , wound dressing and cell delivery [24][25][26] , among others 3 . Despite its excellent mechanical properties, materials derived from nanocellulose and, in particular, TEMPO-oxidized nanocellulose, have several drawbacks inherent to its nature. For instance, these materials are mostly hydrophilic owing to the high concentration of hydroxyl and carboxylate groups; this causes mechanical instability of the formed materials under wet/humid conditions, and exhibit rather low aspect ratios compared to dissolved polymers. The limited aspect ratio makes it difficult to create oriented structures of cellulose nanofibrils by drawing 27,28 . Many attempts to overcome hydrophilicity challenges have been made through appr...

Aims:  For Ophiostoma (Ceratocystis) ulmi, the ability to undergo morphological change is a crucial factor for its virulence. To gain an understanding of quorum‐sensing activity in O. ulmi as it relates to yeast‐mycelium dimorphism control, this study examines the effects of branched‐chain amino acids as well as their fusel alcohols and fusel acids as quorum sensing molecules. Methods and Results:  In a defined medium containing glucose, proline and salts, O. ulmi grew as yeasts when the culture was inoculated with a high density of spores (2 × 107 CFU ml−1) and as mycelia when inoculated with a low spore density (4 × 105 CFU ml−1). The cultures displaying yeast morphology secreted a quorum‐sensing factor that shifted the morphology from mycelia to yeast. This quorum‐sensing molecule was lipophilic and extractable by organic solvents from the spent medium. Using GC/MS analysis, it was determined that the major compound in the extract was 2‐methyl‐1‐butanol. A similar effect was observed when the branched‐chain amino acids (fusel alcohol precursors) were used as the nitrogen source. E, E‐farnesol had no effect on the morphology of O. ulmi. Conclusions:  Addition of the branched‐chain amino acids or one of the compounds detected in the spent medium, 2‐methyl‐1‐butanol or 4‐hydroxyphenylacetic acid, or methylvaleric acid, decreased germ tube formation by more than 50%, thus demonstrating a quorum sensing molecule behaviour in O. ulmi cultures. Significance and impact of the study:  This study presents advances in the investigation of dimorphism in O. ulmi, complementing the existing scientific basis, for studying, understanding and controlling this phenomenon.

José, "Quorum sensing activity and control of yeastmycelium dimorphism in Ophiostoma floccosum" (2014). Faculty Publications in the Biological Sciences. 560.