High resolution system for nanoparticles hyperthermia efficiency evaluation

A system to evaluate nanoparticles efficiency in hyperthermia applications is presented. The method allows a direct measurement of the power dissipated by the nanoparticles through the determination of the first harmonic component of the in quadrature magnetic moment induced by the applied field. The magnetic moment is measured by using an induction method. To avoid errors and reduce the noise signal a double in phase demodulation technique is used. To test the system viability we have measured nanowires, nanoparticles and copper samples of different volumes to prove by comparing experimental and modeled result

Effects of core position uncertainty on optical shape sensor accuracy

[EN] Optical fiber sensors are now widely recognized as extremely reliable instruments to sense strain. Optical shape sensors consist of multiple single-core optical fibers or multicore optical fibers capable of sensing bending direction and curvature by comparing the longitudinal strain of different cores in an instrumented section and reconstructing the sensor shape. This paper describes a study on the effects of core position errors on the precision of optical shape sensors when measuring strain, bending direction and curvature, and identifies the role of measured curvature and core spacing (distance between section center and external cores), considering 7, 4, and 3-core fiber geometries, three of those most widely employed for sensing applications. The Monte Carlo technique was utilized to reproduce the measurement process. Forty-five simulations, including 3.10(6) trials, were carried out for each geometry with the aim of investigating the law of uncertainty propagation. The results of the analysis, applicable to both multiple single-core fibers and multicore optical sensors equipped with distributed or quasi-distributed strain-sensors, show the effects of core position uncertainty and will be useful for new sensor designs and user options by predicting the achievable performance of these devices.This work was carried out within the ITN-FINESSE framework, funded by the European Union's Horizon 2020 Research and Innovation Program under the Marie Sklodowska-Curie Action Grant Agreement No 722509. It was also supported by the Ministry of Economy and Competitiveness of Spain under the project DIMENSION TEC2017-88029-R.Floris, I.; Calderón García, PA.; Sales Maicas, S.; Adam, JM. (2019). Effects of core position uncertainty on optical shape sensor accuracy. Measurement. 139:21-33. https://doi.org/10.1016/j.measurement.2019.03.031S213313

Measurement uncertainty of multicore optical fiber sensors used to sense curvature and bending direction

[EN] This paper describes a study of the influence of strain measurement uncertainty on sensing curvature and bending direction, considering one of the most widely used fiber geometries for sensing applications (7-core Multicore Fiber) with different core spacings (distance between outer cores and fiber axis). The Monte Carlo method was proposed to simulate the real measurement process and 33 simulations with 106 iterations were performed to determine the laws of propagation of strain measurement uncertainty in calculating curvature and bending direction. The outcomes, which show the strong influence of strain uncertainty and core spacing on the precision of Multicore Fiber sensors, can be used to support the design of new sensors or new fiber geometry and to predict their achievable performance.This work was carried out within the ITN-FINESSE framework, funded by the European Union's Horizon 2020 Research and Innovation Program under the Marie Sklodowska-Curie Action Grant Agreement No 722509. It was also supported by the Ministry of Economy and Competitiveness of Spain under the project DIMENSION TEC-2017-88029-R.Floris, I.; Sales Maicas, S.; Calderón García, PA.; Adam, JM. (2019). Measurement uncertainty of multicore optical fiber sensors used to sense curvature and bending direction. Measurement. 132:35-46. https://doi.org/10.1016/j.measurement.2018.09.033S354613

In Candida parapsilosis the ATC1 gene encodes for an acid trehalase involved in trehalose hydrolysis, stress resistance and virulence

An ORF named CPAR2-208980 on contig 005809 was identified by screening a Candida parapsilosis genome data base. Its 67% identity with the acid trehalase sequence from C. albicans (ATC1) led us to designate it CpATC1. Homozygous mutants that lack acid trehalase activity were constructed by gene disruption at the two CpATC1 chromosomal alleles. Phenotypic characterization showed that atc1Δ null cells were unable to grow on exogenous trehalose as carbon source, and also displayed higher resistance to environmental challenges, such as saline exposure (1.2 M NaCl), heat shock (42°C) and both mild and severe oxidative stress (5 and 50 mM H2O2). Significant amounts of intracellular trehalose were specifically stored in response to the thermal upshift in both wild type and mutant strains. Analysis of their antioxidant activities revealed that catalase was only triggered in response to heat shock in atc1Δ cells, whereas glutathione reductase was activated upon mild oxidative stress in wild type and reintegrant strains, and in response to the whole set of stress treatments in the homozygous mutant. Furthermore, yeast cells with double CpATC1 deletion were significantly attenuated in non-mammalian infection models, suggesting that CpATC1 is required for the pathobiology of the fungus. Our results demonstrate the involvement of CpAtc1 protein in the physiological hydrolysis of external trehalose in C. parapsilosis, where it also plays a major role in stress resistance and virulence

In vitro cell cytotoxicity profile and morphological response to polyoxometalate-stabilised gold nanoparticles

The size and redox properties of molecular polyoxometalates (POMs) make them extremely relevant for bioapplications: from disrupting tumour growth and enzyme inhibition, to DNA-intercalating agents and antimicrobial applications. Their unique ability to reversibly dominate and receive electrons, coupled with their high anionic charge, also makes them suitable for the preparation of zero-valent state metal nanoparticles (NPs) from molecular precursors. Polyoxometalate-stabilised nanoparticles (NPs@POM) are therefore an ideal delivery vehicle for bioactive POMs. Here we show how POM-stabilised gold NPs (AuNPs@POM) are massively internalised into Vero (kidney epithelial) and B16 (skin melanoma) cell lines with variable cytotoxic effects. Cell viability assays and quantification of cytoplasmic membrane composition revealed that the Vero cell line was unaltered by the internalisation of these hybrid particles; while their internalisation in B16 tumour cells produced mild cytotoxic effects and an antiproliferative cell cycle arrest in the G0/G1 and G2/M phases. The observed perturbation of the tumour cell line combined with the high degree of internalisation means that these (or similar) NPs@POM could serve as candidates for a range of bioapplications in diagnostics or therapy

Enhanced exchange and reduced magnetization of Gd in an Fe/Gd/Fe trilayer

5 páginas, 6 figuras.-- PACS number(s): 75.70.−i, 75.47.De, 75.60.EjThe exchange interaction of Gd adjacent to Fe has been characterized by transport measurements on a double spin valve with a Fe/Gd/Fe trilayer as the middle layer. Our measurements show that the ferromagnetism of the Gd is enhanced by the presence of the Fe, and it remains ferromagnetic over its Curie temperature up to a thickness no smaller than 1 nm adjacent to the Fe. This thickness is more than double what has been reported before. Additionally, the saturation magnetization of the thin Gd layer sandwiched in Fe was found to be half of its bulk value. This reduced magnetization does not seem to be related to the proximity of Fe but rather to the incomplete saturation of Gd even for very high fields.This work was partially supported by Project Nos. MAT2008-02770/NAN and MAT2009-08771 from the SpanishMinisterio deCiencia e Innovaci´on. M. Romerawas funded through the FPU Fellowship No. AP2007-00464.Peer reviewe

Synthesis of Ni nanoparticles by dc magnetron sputtering

Magnetic materials have been used with grain sizes down to the nanoscale for longer than any other type of material. The biomedical applications cover from magnetic separation of specific biological entities from their native environment to drug delivery, hyperthermia treatments or MRI contrast enhancement [1]. There are many synthesis methods depending on the final applications of the magnetic nanoparticles [2]. Sputtering methods are less extensively used, maybe due to the low efficiency of the process, however these methods have the advantage of a good control on the composition and size of the particles. Research has focused mainly on Fe [3,4], Co [5] and FeCo alloys [6]. In this work we apply the dc magnetron sputtering technique to the growth of Ni nanoparticles

Synthesis of Fe-Au nanoparticles through phase separation using the gas aggregation technique

During the last veers different type of magnetic materials have been obtained either alloys or nanopor-ritlcs with severall metalllics shells. These particle exhibt better magnetic properties, are biocompatible and have optical properties due to their shell noble metal layer, this is possible, to synthesize heterostructured nanoparticles with care/shell structure by using sputtering targets consisting of alloys of different materials. In the case of such materials have different surface energies and atomic sizes, there are diffusion processes which lead to the formation of structured nanoparticles with a shell and core having different composition. In this work we will show the results obtained about Fe-Au nanoparticles grown by I he gas aggregation technique, using magnetron sputering sources. Colloids prepared from sputtered deposits of heterostructed nanoparticles exhibit less aggregation when compared to suspensions obtained from pure magnetic materials. Spectrophotometry measurement show the presence of gold at the surface of the nanoparticles. Magnetic properties of such particle are analyzed by VSM. Compasition end structural analysis are studied by TEM and ÉDA