Nanopartikula magnetikoak: zenbait aplikazio medikutzan

Azken urteotan, nanopartikula magnetikoak garrantzia hartzen ari dira medikuntza arloan. Nanometrikoak izateagatik, partikula magnetiko horiek galdu egiten dute oroimen magnetikoa, eta ondorioz ez dute aglomeraturik sortzen eta odol-zir kuituan ibiltzeko gai dira. Partikula horiek aplikazio asko dituzte, besteak beste eskualde finko bateko tenperatura igotzeko (hipertermia) edo kanpo eremu magnetikoak erabiliz, farmakoak xede-ehunetara garraiatzeko. Magnetic particles at the nanoscale have two interesting features that make them attractive for biomedical applications: firstly, they have a large magnetic susceptibility, which makes them be easily attracted by magnets, and secondly, they do not re- tain magnetic memory, which means that once the magnetic force is off they disperse and do not form aggregates, minimizing the risk of obstructing the blood stream. Currently magnetic nanoparticles are commonly used as contrast agents for magnetic res- onance imaging of certain organs, especially the liver. In this article we will examine two of the applications that are being most widely studied in the last years. On the one hand is the localized magnetic hyperthermia , which consists on attaching magnetic nanoparticles to tumour cells and apply an alternating magnetic field. This field heats up the particles and the cells they are attached to. On the other hand, magnetic nanoparticles may be used as drug carriers that can be directed to the damaged tissue by external magnetic fields, avoiding the drug spreading to healthy tissues. We will overview the properties and current status of both techniques and the drawbacks to overcome before they can be of clinical us

Nanopartikula magnetikoak: zenbait aplikazio medikutzan

Azken urteotan, nanopartikula magnetikoak garrantzia hartzen ari dira medikuntza arloan. Nanometrikoak izateagatik, partikula magnetiko horiek galdu egiten dute oroimen magnetikoa, eta ondorioz ez dute aglomeraturik sortzen eta odol-zir kuituan ibiltzeko gai dira. Partikula horiek aplikazio asko dituzte, besteak beste eskualde finko bateko tenperatura igotzeko (hipertermia) edo kanpo eremu magnetikoak erabiliz, farmakoak xede-ehunetara garraiatzeko. Magnetic particles at the nanoscale have two interesting features that make them attractive for biomedical applications: firstly, they have a large magnetic susceptibility, which makes them be easily attracted by magnets, and secondly, they do not re- tain magnetic memory, which means that once the magnetic force is off they disperse and do not form aggregates, minimizing the risk of obstructing the blood stream. Currently magnetic nanoparticles are commonly used as contrast agents for magnetic res- onance imaging of certain organs, especially the liver. In this article we will examine two of the applications that are being most widely studied in the last years. On the one hand is the localized magnetic hyperthermia , which consists on attaching magnetic nanoparticles to tumour cells and apply an alternating magnetic field. This field heats up the particles and the cells they are attached to. On the other hand, magnetic nanoparticles may be used as drug carriers that can be directed to the damaged tissue by external magnetic fields, avoiding the drug spreading to healthy tissues. We will overview the properties and current status of both techniques and the drawbacks to overcome before they can be of clinical us

Retrieving the thermal diffusivity and effusivity of solids from the same frequency scan using the front photopyroelectric technique

The photopyroelectric (PPE) technique in the front configuration consists in illuminating one surface of a pyroelectric slab while the other surface is in contact with the test sample. This method has been widely used to measure the thermal effusivity of liquids. Recently, it has been extended to measure the thermal effusivity of solids, by taking into account the influence of the coupling fluid layer used to guarantee the thermal contact. In both cases, the sample (liquid or solid) must be very thick. In this work, we propose a classical frequency scan of a thin sample slab to retrieve the thermal diffusivity and effusivity simultaneously. We use the amplitude and the phase of the front PPE signal, which depend on four parameters: the sample diffusivity and effusivity, the coupling fluid thickness and the coefficient of heat losses. It is demonstrated that the four quantities are not correlated. PPE measurements performed on a set of calibrated solids confirm the ability of the method to obtain the thermal diffusivity and effusivity of solids accurately.This work has been supported by Ministerio de Economía y Competitividad, (DPI2016-77719-R, AEI/FEDER, UE), by Gobierno Vasco (KK-2016/00027) and by Universidad del País Vasco UPV/EHU (GIU16/33)

Termografia infragorri aktiboa materialen azterketarako

Active lnfrared Thermography techniques are based in detecting thermal waves previously induced in a material. This thermal waves wi ll travel through the material and carry with them information of the interna! structure of the material. Measuring the surface temperature allows to obtain that information . In infrared thermography the surface temperature is meas u red by means of an infrared camera.During the last years these techniques have had a great development because they are very fast techniques , because no contact to the material is needed and because they can be classified as non-destructive techniques.In this work, we will see some examples of active infrared thermography such as pulsed infrared thermography, modulated infrared thermography and vibrothermography.; Terrnografia infragorri aktiboaren oi narria material batean induzitzen diren uhin termjkoen detekzioan datza. Uhin termiko horiek materialean zehar hedatuko dira eta materialaren propietate termikoei eta barne-egiturari buruzko informazioa garraiatuko dute; materialaren gainazalean tenperatura neurtuz lar daiteke informazio hori. Termografia infragorrian tenperatura kamara infragorri baten bitartez neurtzen da.Azken urteetan teknika fototermikoek eta, bereziki, termografia infragorriak garapen handia izan dute, materialak karakterizatzeko teknika azkarrak direlako, laginarekin kontakturik behar ez dutelako eta entsegu ez-suntsi tzaileen harnean sailka daitezkeelako.Lan honetan, termografia infragorri aktiboaren oinarriak ikusiko ditugu eta zenbait aplikaz io aztertuko ditugu hiru teknika erabiliz: termografia infragorri pultsatua, termografia infragorri modulatua eta bibrotermografia

Scalable IoT Architecture for Monitoring IEQ Conditions in Public and Private Buildings

This paper presents a scalable IoT architecture based on the edge–fog–cloud paradigm for monitoring the Indoor Environmental Quality (IEQ) parameters in public buildings. Nowadays, IEQ monitoring systems are becoming important for several reasons: (1) to ensure that temperature and humidity conditions are adequate, improving the comfort and productivity of the occupants; (2) to introduce actions to reduce energy consumption, contributing to achieving the Sustainable Development Goals (SDG); and (3) to guarantee the quality of the air—a key concern due to the COVID-19 worldwide pandemic. Two kinds of nodes compose the proposed architecture; these are the so-called: (1) smart IEQ sensor nodes, responsible for acquiring indoor environmental measures locally, and (2) the IEQ concentrators, responsible for collecting the data from smart sensor nodes distributed along the facilities. The IEQ concentrators are also responsible for configuring the acquisition system locally, logging the acquired local data, analyzing the information, and connecting to cloud applications. The presented architecture has been designed using low-cost open-source hardware and software—specifically, single board computers and microcontrollers such as Raspberry Pis and Arduino boards. WiFi and TCP/IP communication technologies were selected, since they are typically available in corporative buildings, benefiting from already available communication infrastructures. The application layer was implemented with MQTT. A prototype was built and deployed at the Faculty of Engineering of Vitoria-Gasteiz, University of the Basque Country (UPV/EHU), using the existing network infrastructure. This prototype allowed for collecting data within different academic scenarios. Finally, a smart sensor node was designed including low-cost sensors to measure temperature, humidity, eCO2, and VOC.The authors wish to express their gratitude, for supporting this work, to the Fundación Vital through project VITAL21/05 and the University of the Basque Country (UPV/EHU), through the Campus Bizia Lab (CBL) program. Partial support has been also received from the Basque Government, through project EKOHEGAZ (ELKARTEK KK-2021/00092), the Diputación Foral de Álava (DFA) through the project CONAVANTER, and the UPV/EHU through the GIU20/063 grant

Tailoring the magnetocaloric, magnetic and thermal properties of Dy6(Fe,Mn)X2 intermetallics (X==Sb, Te, Bi)

[EN] The structural, magnetic, magnetocaloric (MCE) and thermal properties of seven Fe2P-type Dy6(Fe,Mn)X2 (X=Sb, Bi, Te) intermetallics (space group P 6 over line 2 m, N 189, hP9) have been experimentally studied. They present a paramagnetic to ferromagnetic transition (in the range 129-370 K), followed, as temperature decreases, by a spin-reorientation one (from 52 to 170 K) and a ground magnetic state at 2 K with anti-ferromagnetic components. This state turns into a ferromagnetic state when a magnetic field is applied. The critical exponents beta,gamma,delta related to the PM-FM transition point to long range order interactions but in most compounds their values severely deviate from the Mean Field class, presenting an unconventional critical behavior, probably due to magnetocrystalline anisotropies. This magnetic complexity has the consequence that in every intermetallic three MCE effects arise: Two direct magnetocaloric effects (DMCE) with a table-like effect in between (from 40 K to more than 400 K), with moderate values of the magnetic entropy maxima (up to 6.9 J/kgK for 140 Delta H = 5 T, with the tableau in-between being around 4 J/kgK, for Dy6FeSb2 and Dy6FeSbTe). The calculation of the Thermal Average Entropy Change allows to place the properties of two compounds (Dy6FeSb2 and Dy6FeSbTe) close to other rare earth based high entropy alloys described in literature. The seven compounds present a relevant third MCE, inverse, below 25 K, with a value as high as 17.8 J/kgK (140 Delta H = 5 T) for Dy6FeSbTe. The maximum of the magnetic entropy change at the Curie tem-perature has been shown to scale with the critical exponents found and universal curves have been built. Finally, the thermal diffusivities in the range of the DMCE have been measured, with the result that they present good values (between 1 and 3 mm2/s) to be used in real magnetocaloric refrigeration systems.This work has been supported by Universidad del Pais Vasco UPV/EHU (project GIU19/058) and the Russian Fund for Basic Research (project No 20-03-00209-a). A. Herrero thanks the Department of Education of the Basque Government as grantee of the programme "Programa Predoctoral de Formacion de Personal Investigador No Doctor". The authors thank for technical and human support provided by SGIker of UPV/EHU, specially the fruitful discussions with Dr. I. Orue

Selecting optimal R6TX2 intermetallics (R = Gd, Tb, Dy; T = Mn, Fe, Co, Ni; X = Sb, Te) for magnetic refrigeration

A complete experimental study of the physical properties playing a relevant role on magnetic refrigeration application (structural, magnetic, magnetocaloric and thermal) has been performed over nine selected Fe2P-type R6TX2 (R= Gd, Tb, Dy; T= Mn, Fe, Co, Ni; X=Sb, Te) intermetallic compounds, to work close to room temperature. Two magnetic phase transitions are present on these materials: a paramagnetic to ferromagnetic transition in the range 182-282 K and a spin reorientation transition in the range 26-76 K. As a consequence, two peaks related to a direct magnetocaloric effect (DMCE) appear in the magnetic entropy change, generating a wide table-like plateau region in between both peaks, which is required to improve the efficiency of refrigerators following an Ericsson cycle. The highest magnetic entropy peak value for μ0ΔH = 5 T is found for Tb2Dy4FeSb2, with 7.72 J/kg K around 182 K. For the same applied field the other compounds show moderate values around room temperature (2.88-4.53 J/Kg K). However, the superposition of the two peaks results in huge refrigerant capacity values, up to RCFWHM(5 T)=1103.04 J/kg in the case of Tb2Dy4FeSb2. The thermal diffusivity, effusivity conductivity and specific heat have been measured at room temperature, and the temperature dependence of the former has been obtained around the relevant magnetic phase transition region, with values in the range 1.3-2.3 mm2/s, which are good for magnetic refrigerators under high working frequencies. The study is completed with a rigorous critical behavior analisis of the second order PM-FM transition. The critical exponent γ points to long range order interactions, in general, while β values are in the range (0.59-0.90), indicating a deviation from theoretical models as a reflection of the magnetic complexity in these compounds. The critical exponents have been used to confirm the scaling relations of magnetocaloric properties, and the scaling of refrigerant capacity (RC) values in materials presenting two magnetic phase transitions is addressed, concluding that for a correct scaling of RC the magnetic entropy change peak must be considered symmetric. The role of each atom on the properties of the compounds is discussed.This work was supported by Departamento de Educación del Gobierno Vasco (project IT1430-22) and the Russian Fund for Basic Research through the project no. 20-03-00209-a, as well as by an ICDD (International Centre for Diffraction Data) (USA) grant n 05-07

Termografia infragorri aktiboa materialen azterketarako

Active lnfrared Thermography techniques are based in detecting thermal waves previously induced in a material. This thermal waves wi ll travel through the material and carry with them information of the interna! structure of the material. Measuring the surface temperature allows to obtain that information . In infrared thermography the surface temperature is meas u red by means of an infrared camera.During the last years these techniques have had a great development because they are very fast techniques , because no contact to the material is needed and because they can be classified as non-destructive techniques.In this work, we will see some examples of active infrared thermography such as pulsed infrared thermography, modulated infrared thermography and vibrothermography.; Terrnografia infragorri aktiboaren oi narria material batean induzitzen diren uhin termjkoen detekzioan datza. Uhin termiko horiek materialean zehar hedatuko dira eta materialaren propietate termikoei eta barne-egiturari buruzko informazioa garraiatuko dute; materialaren gainazalean tenperatura neurtuz lar daiteke informazio hori. Termografia infragorrian tenperatura kamara infragorri baten bitartez neurtzen da.Azken urteetan teknika fototermikoek eta, bereziki, termografia infragorriak garapen handia izan dute, materialak karakterizatzeko teknika azkarrak direlako, laginarekin kontakturik behar ez dutelako eta entsegu ez-suntsi tzaileen harnean sailka daitezkeelako.Lan honetan, termografia infragorri aktiboaren oinarriak ikusiko ditugu eta zenbait aplikaz io aztertuko ditugu hiru teknika erabiliz: termografia infragorri pultsatua, termografia infragorri modulatua eta bibrotermografia