Although seagrass-based indicators are widely used to assess coastal ecosystem status, there is little universality in their application. Matching the plethora of available indicators to specific ...management objectives requires a detailed knowledge of their species-specific sensitivities and their response time to environmental stressors. We conducted an extensive survey of experimental studies to determine the sensitivity and response time of seagrass indicators to ecosystem degradation and recovery. We identified seagrass size and indicator type (i.e. level of biological organization of the measure) as the main factors affecting indicator sensitivity and response time to degradation and recovery. While structural and demographic parameters (e.g. shoot density, biomass) show a high and unspecific sensitivity, biochemical/physiological indicators present more stressor-specific responses and are the most sensitive detecting early phases of environmental improvement. Based on these results we present a simple decision tree to assist ecosystem managers to match adequate and reliable indicators to specific management goals.
The internalization and biocompatibility of iron oxide nanoparticles surface functionalized with four differently charged carbohydrates have been tested in the human cervical carcinoma cell line ...(HeLa). Neutral, positive, and negative iron oxide nanoparticles were obtained by coating with dextran, aminodextran, heparin, and dimercaptosuccinic acid, resulting in colloidal suspensions stable at pH 7 with similar aggregate size. No intracellular uptake was detected in cells incubated with neutral charged nanoparticles, while negative particles showed different behaviour depending on the nature of the coating. Thus, dimercaptosuccinic-coated nanoparticles showed low cellular uptake with non-toxic effects, while heparin-coated particles showed cellular uptake only at high nanoparticle concentrations and induced abnormal mitotic spindle configurations. Finally, cationic magnetic nanoparticles show excellent properties for possible in vivo biomedical applications such as cell tracking by magnetic resonance imaging (MRI) and cancer treatment by hyperthermia: (i) they enter into cells with high effectiveness, and are localized in endosomes; (ii) they can be easily detected inside cells by optical microscopy, (iii) they are retained for relatively long periods of time, and (iv) they do not induce any cytotoxicity.
The applications of exchange coupled bi-magnetic hard/soft and soft/hard ferromagnetic core/shell nanoparticles are reviewed. After a brief description of the main synthesis approaches and the ...core/shell structural–morphological characterization, the basic static and dynamic magnetic properties are presented. Five different types of prospective applications, based on diverse patents and research articles, are described: permanent magnets, recording media, microwave absorption, biomedical applications and other applications. Both the advantages of the core/shell morphology and some of the remaining challenges are discussed.
Ferrimagnetic iron oxide nanoparticles (magnetite or maghemite) have been the subject of an intense research, not only for fundamental research but also for their potentiality in a widespread number ...of practical applications. Most of these studies were focused on nanoparticles with spherical morphology but recently there is an emerging interest on anisometric nanoparticles. This review is focused on the synthesis routes for the production of uniform anisometric magnetite/maghemite nanoparticles with different morphologies like cubes, rods, disks, flowers and many others, such as hollow spheres, worms, stars or tetrapods. We critically analyzed those procedures, detected the key parameters governing the production of these nanoparticles with particular emphasis in the role of the ligands in the final nanoparticle morphology. The main structural and magnetic features as well as the nanotoxicity as a function of the nanoparticle morphology are also described. Finally, the impact of each morphology on the different biomedical applications (hyperthermia, magnetic resonance imaging and drug delivery) are analysed in detail.
We would like to dedicate this work to Professor Carlos J. Serna, Instituto de Ciencia de Materiales de Madrid, ICMM/CSIC, for his outstanding contribution in the field of monodispersed colloids and iron oxide nanoparticles. We would like to express our gratitude for all these years of support and inspiration on the occasion of his retirement.
This review summarizes the colloidal synthetic routes leading to magnetic iron oxide nanoparticles with different morphologies and analyses the key parameters on each route that govern particle size and shape. Structural and magnetic properties for each morphology are also reviewed and related to the synthetic route as well as the advantages of using magnetic anisometric nanoparticles in biomedical applications and others. Display omitted
Strains of Schizosaccharomyces pombe are being increasingly investigated with regards to their grape winemaking potential either in combination with the typical production yeast, Saccharomyces ...cerevisiae, or in monoseptic fermentations. Their ethanol tolerance and ability to degrade L-malic acid is oenologically convenient but contrasts with the comparatively high acetic acid and acetaldehyde formation potential which is considered undesirable, especially in white winemaking. The purpose of this work was to investigate the performance of a selected S. pombe strain in monoseptic femerntations of white grape must. Traditional batch fermentations were compared with an innovative and automated fed-batch fermentation technique were sugar concentrations are kept low during fermentations to decrease sugar induced osmotic stress. Because of its known effect on growth and ethanol tolerance, the effect of Mg was also tested. While Mg supplementation was not shown to significantly influence residual values of sugars, ethanol, glycerol, organic acids and acetaldehyde, the application of the fed-batch technique led to a fundamental change in yeast physiology. While glycerol values were only slightly reduced, the fed-batch approach allowed obtaining wines devoid of acetic acid whose levels were considerable in wines produced by the traditional batch technique (0.6 g/L). The work demonstrates that the acetic acid metabolism of S. pombe is associated to sugar induced osmotic stress such as for S. cerevisiae, too, and may be controlled by application of suitable fermentation techniques for winemaking.
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•Significant production of acetic acid in traditional batch fermentation•The fed-batch approach allos to prevent acetic acid formation by S. pombe.•Grape must supplementation with Mg did not affect metabolism.
The application of magnetic nanoparticles requires large amounts of materials of reproducible quality. This work explores the scaled-up synthesis of multi-core iron oxide nanoparticles through the ...use of thermal decomposition in organic media and kilograms of reagents. To this end, we check the effect of extending the high temperature step from minutes to hours. To address the intrinsic variability of the colloidal crystallization nucleation process, the experiments were repeated and analyzed statistically. Due to the simultaneity of the nuclei growth and agglomeration steps, the nanostructure of the samples produced was a combination of single- and multi-core nanoparticles. The main characteristics of the materials obtained, as well as the reaction yields, were analyzed and compared. As a general rule, yield, particle size, and reproducibility increase when the time at high temperature is prolonged. The samples obtained were ranked in terms of the reproducibility of different structural, colloidal, and magnetic features. The capability of the obtained materials to act as nanoheaters in magnetic hyperthermia was assessed, showing a strong dependence on the crystallite size (calculated by X-ray diffraction), reflecting the nanoparticle volume with a coherent magnetization reversal.
Magnetite (Fe 3 O 4 ) nanoparticles with very narrow particle size distribution can be obtained by decomposition of an organometallic compound in the presence of oleic acid. It has been shown that ...the carboxylic acid catalyzes the reaction leading to decreased decomposition temperatures and, consequently, as the surfactant concentration increases, smaller particles are formed. Precursors such as Fe(CO) 5 , iron acetylacetonate, and iron-oleate complexes, previously formed from an iron salt, have been used for the preparation of magnetite particles. Although the particles are magnetite in all cases, the size, shape, and distribution of nanoparticles differ depending on the precursor and consequently the samples show different magnetic behavior. Besides, a different mechanism of formation of the nanoparticles is expected and related to the decomposition rate of the precursor
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