We studied GMI effect and magnetic properties of Finemet-type FeCuNbSiB microwires. We observed that GMI magnetic field and frequency dependences and magnetic softness of composite microwires ...produced by the Taylor-Ulitovski technique can be tailored either controlling magnetoelastic anisotropy of as-prepared FeCuNbSiB microwires or controlling their structure by heat treatment or changing the fabrication conditions. High GMI effect has been observed in as-prepared Fe-rich and heat treated microwires with nanocrystalline structure.
Magnetoimpedance (MI) response of near-zero magnetostriction Co-based amorphous ribbons in as-cast (with four different wide dimension) state, and exhibiting a macroscopic uniaxial magnetic ...anisotropy induced by stress-annealing treatment (300 MPa applied tensile stress at different temperature i.e., 340, 360, and 400 °C, respectively, during 1 h) is investigated in the frequency range from 10 MHz up to 1000 MHz. Comparison among MI effect of as-cast state and stress-annealed ribbons is discussed. It is remarkable that a more spectacular and defined MI effect is observed in the stress-annealed ribbons owing to the presence of a macroscopic uniaxial transverse magnetic anisotropy developed with the stress-annealing treatment that enhances the transverse component of the magnetic susceptibility. The influence of a preceding stress relief before the stress-annealing process on the MI effect is also analyzed.
We investigate the direct and inverse magnetocaloric effect in Ni 45.5Mn 43.0In 11.5 Heusler alloy ribbons comparing the results obtained for the as-quenched sample with the ones after different ...annealing procedures. An enhancement and shift of the entropy maximum to near room temperature is observed in all annealed samples. A remarkable magnetocaloric effect is observed in samples with short-time treatment (10 minutes) and at the lowest annealing temperature. We show that the suppressing of uncompensated martensitic transition and thermal hysteresis are both influenced by the heat treatment. Also, an improvement on Curie's temperature is observed and, at low magnetic field, it has been risen up to 310K. Our results demonstrate that the martensitic transformation is highly sensitive to the applied magnetic field and also to the annealing treatment, which means that the magnetocaloric effect can be tuned showing different behaviors for each sample
Authors are thankful to Spanish MICINN for financial support: MAT2009-13108-C02-01-02 and MAT2010-20798-C05-04
The intrinsic physicochemical properties of carbon nanotubes (CNTs) make them unique tools in nanotechnology. Their elemental composition, resilience, thermal properties, and surface reactivity make ...CNTs also of undisputed interest in biotechnology. In particular, their extraordinary ability to capture biomolecules on their surface makes them essential in this field. The proteins adsorbed on the CNTs create a biological coating that endows them the ability to interact with some cell receptors, penetrate membranes or interfere with cell biomechanics, thus behaving as an active bio-camouflage. But some of these proteins unfold, triggering an immune response that unpredictably changes the biological activity of CNTs. For this reason, the control of the biocorona is fundamental in the nanobiotechnology of CNTs.
Using TEM and AFM here we demonstrate a significant increase in CNTs diameter after protein functionalization. A quantitative analysis using TGA revealed that between 20 and 60% of the mass of functionalized nanotubes corresponds to protein, with single-walled CNTs capturing the highest amounts. To qualitatively/quantitatively characterize these biocoatings, we studied the biochemical "landscape" of the proteins captured by the different nanotubes after functionalization under various conditions. This study revealed a significant variability of the proteins in the corona as a function of the type of nanotube, the functionalization temperature, or the time after exposure to serum. Remarkably, the functionalization of a single type of CNT with sera from various human donors also resulted in different protein landscapes. Given the unpredictable assortment of proteins captured by the corona and the biological implications of this biocoating, we finally designed a method to genetically engineer and produce proteins to functionalize nanotubes in a controlled and customizable way.
We demonstrate the high unpredictability of the spontaneous protein corona on CNTs and propose a versatile functionalization technique that prevents the binding of nonspecific proteins to the nanotube to improve the use of CNTs in biomedical applications.
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•Exploring the cell uptake of the free labelled nanocarrier Laponite by confocal Raman imaging.•Tracking the nanomaterial from the cell surface to the inner cell, without dye-labeling ...steps.•Raman spectroscopy is sensitive to detect Laponite signalling when it is dispersed in serum and in cell cultures.•Mapping the intracellular structures allows to discard Laponite adhesion to the membrane surface of the cell.
Laponite is a nanoplatform that has been successfully used as a new biomaterial for drug delivery, tissue engineering and bioimaging at the nanoscale. In general, a deep knowledge of the mechanism interaction of the nanomaterial with biological components in a physiological environment is highly desirable for properly characterizing its therapeutic efficacy and toxicology. Up to know, the use of fluorescent dyes labelling both, the nanomaterial and cell components, has been a requirement to characterize the cell uptake and to visualize the entrance of the nanomaterial into the cytosol and the cell nucleus. The used of fluorophores usually perturb the physiological medium and can interfere in the nanomaterial cell interaction. A new Raman imaging methodology to track the uptake and internalization of Laponite nanoparticles into J774 macrophages line cells is presented in this work. The combination of Raman spectroscopy and confocal microscopy provides direct information about the localization of the nanoparticle into the cell, through its unique vibrational fingerprint without labelling or adding dyes, and taking advantage of the fact that Laponite and biological molecules bands can be clearly differentiated.
The application of nanomaterials in the fields of medicine and biotechnology is of enormous interest, particularly in the areas where traditional solutions have failed. Unfortunately, there is very ...little information on how to optimize the preparation of nanomaterials for their use in cell culture and on the effects that these can trigger on standard cellular systems. These data are pivotal in nanobiotechnology for the development of different applications and to evaluate/compare the cytotoxicity among the different nanomaterials or studies. The lack of information drives many laboratories to waste resources performing redundant comparative tests that often lead to partial answers due to differences in (i) the nature of the start-up material, (ii) the preparation, (iii) functionalization, (iv) resuspension, (v) the stability/dose of the nanomaterial, etc. These variations in addition to the different analytical systems contribute to the artefactual interpretation of the effects of nanomaterials and to inconsistent conclusions between different laboratories. Here, we present a brief review of a wide range of nanomaterials (nanotubes, various nanoparticles, graphene oxide, and liposomes) with HeLa cells as a reference cellular system. These human cells, widely used as cellular models for many studies, represent a reference system for comparative studies between different nanomaterials or conditions and, in the last term, between different laboratories.
Understanding the biological effects triggered by nanomaterials is crucial, not only in nanomedicine but also in toxicology. The dose-response relation is relevant in biological tests due to its use ...for determining appropriate dosages for drugs and toxicity limits. Carbon nanotubes can trigger numerous unusual biological effects, many of which could have unique applications in biotechnology and medicine. However, their resuspension in saline solutions and the accurate determination of their concentration after dispersion in biological media are major handicaps to identify the magnitude of the response of organisms as a function of this exposure. This difficulty has led to inconsistent results and misinterpretations of their
in vivo
behavior, limiting their potential use in nanomedicine. The lack of a suitable protocol that allows comparing different studies of the content of carbon nanotubes and their adequate resuspension in culture cell media gives rise to this study. Here, we describe a methodology to functionalize, resuspend and determine the carbon nanotube concentration in biocompatible media based on UV-Vis spectroscopy. This method allows us to accurately estimate the concentration of these resuspended carbon nanotubes, after removing bundles and micrometric aggregates, which can be used as a calibration standard, for dosage-dependent studies in biological systems. This method can also be extended to any other nanomaterial to properly quantify the actual concentration.
A complete method to disperse, functionalize and accurately quantify carbon nanotubes for biological applications in nanomedicine is developed and described.
This review examines the behaviour and productivity of the water buffalo (Bubalus bubalis) under different breeding systems and in relation to meat and milk production. At present, the steady ...increment in the consumption of products and sub-products of this species has generated the need to increase the number of animals incorporated into production by progressively expanding the use of stabling systems, reducing the space available to these animals, and applying techniques developed previously for meat and milk production in bovines. However, because such adaptations often fail to take into account important biological and behavioural features of these animals, they may result in serious problems of animal welfare. On the other hand, it is known that water buffaloes adapt well to humid tropical climates, especially in systems that provide extensive, continuous pastureland. These species are highly susceptible to thermal stress, a fact that leads them to constantly perform wallowing behaviour. For all these reasons, open-air and, above all, silvopastoral, systems represent attractive options because they combine the presence of forage plants with trees that provide natural shade and serve as wind barriers, thus attenuating the negative effects of tropical climes. These measures help increase productivity by promoting greater forage consumption and fostering the expression of the species’ natural behaviours, but the reduction in human contact affects their welfare. Hence, this review concludes that welfare is a fundamental concept that must be taken into account in the development of systems for water buffalo production.
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