Llibre III Jornada IN2UB 2010

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Disseny gràfic i maquetació: Cristina Muñoz Idoate | www.idoate.com

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ABSTRACTS

taula de continguts 5

Salutaci贸 del director

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Registre de participants

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Programa general

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Keynote speaker

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Abstracts

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Posters

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Benvolguts investigadors i investigadores,

Em plau presentar-vos aquest resum, que inclou les xerrades i pòsters que alguns de vosaltres ens vau oferir amb motiu de la III JORNADA IN2UB, celebrada el passat 13 d’octubre de 2010.

Un any més, vull agrair-vos a tots el vostre entusiasme a l’hora de participar a la jornada. En aquesta jornada en concret, vull agrair la participació de Rolf Möller, de la Universitat de Duisburg-Essen, una de les universitats membres de la xarxa IRUN, i de Ramon Alcubilla, de la UPC, com a testimoni de l’aliança entre aquesta universitat i la UB pel que fa al projecte Barcelona Knowledge Campus (BKC).

El meu agraïment també a Lluïsa Pérez i a Ramon Vicente pel seu suport en l’organització científica, i a les dues chairwomen de la JORNADA, Mª Luisa García i Francesca Peiró.

L’edició del recull ha anat a cura de Meritxell Salvany, gestora de l’institut, mentre que el disseny gràfic és de Cristina Muñoz idoate. Volem agrair-los a elles també la seva col.laboració, així com agraïm a Isabel Calaf i a Salvador Piqué, del Col•legi Oficial de Metges de Barcelona (COMB), la seva bona feina pel que fa a la logística de la jornada.

Recordeu que podeu consultar també aquest recull al web http://www. ub.edu/in2ub.

Esperem que la jornada hagi estat enriquidora per a tots vosaltres i que l’any vinent ens tornarem a trobar amb noves experiències i noves fites.

Amílcar Labarta Director de l’IN2UB

Barcelona, desembre de 2010

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III Jornada In2UB - 13 Octubre 2010

LLISTA DE PARTICIPANTS NOM

COGNOM 1

Sergio

Illera

Ramon

Alcubilla

Anna

Alemany

Rosa Ma.

Aparicio

Hicham Manuel Xavier

Batlle

Valentino

Bianco

Edgar Julián

Cabrera

Ana Cristina

Calpena

Carla

Carbonell

Josep

COGNOM 2

ALTRES OBSERVACIONS

FACULTAT

DEPARTAMENT

FÍSICA

Electrònica

Arias

FÍSICA

Fonamental

Pelegrín

FARMÀCIA

Farm. i Tecnologia Farmac.

Bakkali

FÍSICA

Fonamental

Barranco

FÍSICA

ECM

FÍSICA

Fonamental

FÍSICA

Fonamental

FÍSICA

Aplicada i Òptica

Campmany

FARMÀCIA

Farm. i Tecnologia Farmac.

Cortés

FÍSICA

Fonamental

Claret

QUÍMICA

Química Física

Meritxell

Cortés

QUÍMICA

Química Física

Immaculada

Dinarès

FARMÀCIA

Farmacol. I Quím. Terap.

Oscar

Domènech

Cabrera

FARMÀCIA

Físicoquímica

M. Antonia

Egea

Gras

FARMÀCIA

Físicoquímica

Gustavo

Egea

Guri

MEDICINA

Biologia Cel·lular…

Elvira

Escribano

Ferrer

FARMÀCIA

Farm. i Tecnologia Farmac.

Marta

Espina

García

FARMÀCIA

Físicoquímica

Joan

Estelrich

Latràs

FARMÀCIA

Físicoquímica

Sonia

Estradé

FÍSICA

Electrònica

Francisco

Fernández

FARMÀCIA

Farm. i Tecnologia Farmac.

Federico

Ferrarese

FÍSICA

Electrònica

Ana

Flo

Paloma

Florez

Arantxa

Fraile

Rodríguez

Xavier

Garcia

Capdevila

Antoni

Garcia

Santiago

Ma José

García

Celma

Núria

García

Marisa

García

Ma. Luisa

PONENT UPC

Gelabert

Campos Sierra

FARMÀCIA FARMÀCIA

Farm. i Tecnologia Farmac.

FÍSICA

Fonamental

QUÍMICA

C. dels Mat. i Eng.Metal·lúrgica

FÍSICA

Fonamental

FARMÀCIA

Farm. i Tecnologia Farmac.

Castelló

FÍSICA

Electrònica

López

FARMÀCIA

Fisicoquímica

Garduño

Ramírez

FARMÀCIA

Convidada A. C. Calpena

Elisabet

González

Mira

FARMÀCIA

Fisicoquímica

Frank

Güell

FÍSICA

Electrònica

Oriol

Güell

QUÍMICA

Química Física

Jordi

Hernández

Borrell

FARMÀCIA

Fisicoquímica

Sergi

Hernández

Márquez

FÍSICA

Electrònica

Sergi

Hernández

Navarro

QUÍMICA

Química Física

Narcís

Homs

Martí

QUÍMICA

Química Inorgànica

PONENT IN2

PONENT IN2

PONENT IN2

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ALTRES OBSERVACIONS

NOM

COGNOM 1

COGNOM 2

FACULTAT

DEPARTAMENT

Jordi

Ignés

Amílcar

Labarta

Mullol

QUÍMICA

Química Física

Rodríguez

FÍSICA

Fonamental

Jacinto

Lauroba

Raquel

Lázaro

Cano

FARMÀCIA FARMÀCIA

Farm. i Tecnologia Farmac.

Julià

López

Vidrier

FÍSICA

Electrònica

Toni

Luque

Santolaria

FÍSICA

Fonamental

Carlos

Martínez

Boubeta

FÍSICA

Electrònica

Alexander

Martínez

Concepción

FÍSICA

Electrònica

Rolf

Möller

M. Teresa

Montero

FARMÀCIA

Fisicoquímica

Miguel

Morales

QUÍMICA

C. dels Mat. i Eng.Metal·lúrgica

Genoveva

Morral

Ruiz

FARMÀCIA

Farm. i Tecnologia Farmac.

Daniel

Navajas

Navarro

MEDICINA

Ciències Fisiològiques

Lara

Ortas

Pomer

FARMÀCIA

Farmacol. I Quím. Terap.

Francesca

Peiró

Martínez

FÍSICA

Electrònica

Paolo

Pellegrino

Oriol

Penon

Esteva

M.Lluïsa

Pérez

Garcia

PONENT IN2 PONENT DUISBURG-ESSEN

Barrientos

Companys

FÍSICA

Electrònica

FARMÀCIA

Farmacol. I Quím. Terap.

FARMÀCIA

Farmacol. I Quím. Terap.

PONENT IN2

QUÍMICA

Química Física

PONENT IN2

FÍSICA

Electrònica

Alba

Pulido

Joan Manel

Ramírez

Joana

Rangel

FARMÀCIA

Fisicoquímica

José Manuel

Rebled

FÍSICA

Electrònica

Mafalda

Rodrigues

FARMÀCIA

Farmacol. I Quím. Terap.

Ferran

Roig

FARMÀCIA

Farm. i Tecnologia Farmac.

Albert

Romano

FÍSICA

Electrònica

Francesc

Sagués

Mestre

QUÍMICA

Química Física

Meritxell

Salvany

Balada

Lluis

Sánchez

Murillo

Cristina Mercè Javier

Selva

Sánchez

Carme

Suárez

Germà

Elisa

Vallés

Oriol

Valls

Martha

Vázquez

Saúl

Vélez

Centoral

FÍSICA

Fonamental

Anna

Vilà

Arbonés

FÍSICA

Electrònica

Elena

Xuriguera

QUÍMICA

C. dels Mat. i Eng.Metal·lúrgica

De Araújo

Roig

Gestora IN2 FARMÀCIA

Farmacol. I Quím. Terap.

Seco

FÍSICA

Fonamental

Segarra

QUÍMICA

C. dels Mat. i Eng.Metal·lúrgica

MEDICINA

Biologia Cel·lular…

FARMÀCIA

Fisicoquímica

QUÍMICA

Química Física

FARMÀCIA

Fisicoquímica

Planells

PONENT IN2

FARMÀCIA

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programa 9.20-9.50 Recepció i acollida.

9.50-10.00 Obertura: Amílcar Labarta.

10.00-10.50

Rolf Möller (University of Duisburg-Essen)

10.50-11.20 Coffee break.

11.20-11.45 Ramon Alcubilla (UPC).

11.45-12.10 Mª José García Celma (UB) Development of Medicines in Nanostructured Surfactant Systems.

12.10-12.30 Javier Selva (UB) Silver Sub-nanoclusters Electrocatalyze Ethanol Oxidation and Provide Protection against Ethanol Toxicity in Cultured Mammalian Cells.

12.30-12.50 Carlos Martínez-Boubeta (UB) Ferromagnetic Nanoparticles for Cancer Treatment: Invitro.

Results and Monte Carlo Modelling. Influence of Dipolar Ineractions on Hyperthermia.

13.00 Lunch.

14.30-16.00 Poster Session.

16.00-16.20 Alba Pulido (UB) Two-dimensional Microfluidics on Circuits of Wettability Contrast.

16.20-16.40 Joan Manel Ramírez (UB) Realization of Efficient LED’s Emitting at 1.55 μm.

16.40-17.00 Arantxa Fraile Rodríguez (UB) Probing Single Magnetic Nanoparticles by X-ray Spectromicroscopy.

17.00-17.25 Narcís Homs (UB) The Development of Tailored Co-based Catalysts for Reformation Processes of Biofuels to Hydrogen.

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III Jornada In2UB - 13 Octubre 2010

keynote speakers

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ABSTRACTS

Prof. Rolf Moller

University of Duisburg-Essen Expert in surface science. He obtained his PhD in Physics in 1986 in the University of Freiburg. Then, he went for several post-doc positions. In particular, he stayed for a year in the IBM Laboratory in Switzerland. From 1997 to present, he has been the Chair of the Surface Science Group at the Physics Faculty of the University of Duisburg-Essen.

His group takes also part in the Center for Nanointegration, a nanotechnology center founded for the University of Duisburg in 2005 to promote the research in this field. The areas of interest of Professor Moller are: i) Analysis of organic monolayers on metallic, semi conducting and insulating surfaces; ii) Elementary processes of friction and energy dissipation; and iii) Electronic transport at the nanoscale.

Prof. Ramon Alcubilla

CRNE, Universitat Politècnica de Catalunya (UPC), offered also a talk at the III Jornada IN2UB.

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III Jornada In2UB - 13 Octubre 2010

The development of tailored co-based catalysts for reformation processes of biofuels to hydrogen Narcís Homs and Pilar Ramirez de la Piscina Catalytic Materials Group, MATCAT, Dpt. Química Inorgànica and Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Spain

This talk presents the use of hydrogen in an energy context by means of its application as an energy carrier in fuel cell systems. We will revise the current production of H2 and then we will afford the reformation processes of bio-alcohols as an alternative route for the H2 production.

Although H2 is the most abundant element in the Universe, on the Earth is only combined mainly forming part of water, biomass and fossil hydrocarbons. Nowadays H2 is mainly produced from fossil fuels. The use of H2 as an energy carrier will not be accomplished if new production methods are not developed or other sources applied.

One approach is to use the well-known reformation technology to biomass-derived sources. These are for example bio-alcohols which are now currently used as alternative fuels and produced in large amounts worldwide.

The reformation of ethanol is of main interest. However, although the yield of hydrogen is high, the ethanol steamreforming is an endothermic process. It is possible do a combination of the steam-reforming process with the partial oxidation process which is exothermic. Thus it can be achieved an appropriate energy balance and the hydrogen yield may be adjusted. A higher oxygen/ethanol ratio produce a more favourable energy balance but a lower number of H2 mole obtained per mol of ethanol reacted.

and a higher lifetime of the catalysts. The development of efficient catalysts for such processes is of current interest and we present our research achievements on the subject.

Moreover, a general problem of catalytic processes is the deactivation of catalysts and the oxygen introduction may produce a diminution of the carbon deposits on the catalyst and consequently a lower catalyst deactivation

As a conclusion, we demonstrate that the use of bio-alcohols as bio-ethanol and glycerol may be an alternative route to produce H2 which could be used to feed fuel cell devices.

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Ferromagnetic Nanoparticles for Cancer treatment: In-vitro results and Monte Carlo modeling Influence of dipolar interactions on hyperthermia D. Serantes (1), D. Baldomir (1), C. Martinez-Boubeta (2), A. Chalkidou (3), K. Simeonidis (3), M. Angelakeris (3), Th. Samaras (3), O. Kalogirou (3), K. Papazisis (4), C. Dendrinou-Samara (5), Ll. Balcells (6), and B. Martínez (6) (1) Inst. Invest. Tecnolóxicas, and Departamento de Física Aplicada, USC,15782 Santiago de Compostela, Spain (2) IN2UB and Departament d’Electrònica, Universitat de Barcelona, 08028 Barcelona, Spain (3) Department. of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece (4) Molecular Oncology Laboratory, Theagenio Cancer Hospital, 54 007 Thessaloniki, Greece (5) Department of Chemistry, Aristotle University of Thessaloniki, 54 124 Thessaloniki, Greece (6) ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Spain

We are introducing an alternative way for synthesizing high quality metallic, soft ferromagnetic Fe nanoparticles (NPs) with an outer protective MgO sheath, by using one-step vapour-phase condensation.(1) Research on MgO was originally motivated because Mg2+ ions exhibit a biological activity for bone regeneration and it is ubiquitous and essential to all living organism. Accordingly, it was shown that the particles satisfy a few of technical requirements for the practical use in real clinics, such as a high biocompatibility in living cells in-vitro, an injection through blood vessels without any clothing problems in murine model, the potential to be used as contrast agent in the field of diagnostic MRI, and a high absorption rate (SAR) for therapeutic hyperthermia at small particle concentration.

In this report we show both experimental evidences and Monte Carlo modeling of the effects of interparticle dipolar interactions on the hysteresis losses. In-vitro experiments were performed in three different (MDA, SkBr3 and MCF7) human breast cancer cell lines in order to assess cytotoxicity, iron uptake and heating effectiveness. The physical model employed for our numerical simulations is the same as in Ref. (2). Results indicate that an increase of the intensity of dipolar interactions produce a decrease in the magnetic susceptibility and hysteresis losses, thus diminishing the hyperthermia output (Figure). These findings may have important clinical implications for cancer treatment.

Figure: Field-dependence of the SAR for different concentrations (c= 0.007, 0.070, 0.150). Field data is also expressed in real units (Ha= 2K/MS) in order to make easier the comparison with the experimental values for spherical particles (75 nm) with a ferromagnetic behavior well above room temperature, being the effective anisotropy constant (K ≈ 4.5 × 104 J/m3) and saturation magnetization (MS ≈ 210 emu/g).

C. Martinez-Boubeta et al. “Self-assembled multifunctional Fe/MgO nanospheres for magnetic resonance imaging and hyperthermia”, Nanomed.: Nano. Bio. Med. 6, 362 (2010).

(1)

J. García-Otero, M. Porto, J. Rivas, A. Bunde, “Influence of Dipolar Interaction on Magnetic Properties of Ultrafine Ferromagnetic Particles”, Phys. Rev. Lett. 84, 167 (2000).

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III Jornada In2UB - 13 Octubre 2010

Probing single magnetic nanoparticles by x-ray spectromicroscopy A. Fraile Rodríguez (1,2), A. Kleibert (1), J. Bansmann (3), L. J. Heyderman (1) and F. Nolting (1) (1) Paul Scherrer Institut, Villigen PSI, Switzerland (2) Departament de Física Fonamental and IN2UB, Universitat de Barcelona, Barcelona, Spain (3) Department of Surface Chemistry and Catalysis, University of Ulm, Ulm, Germany

Magnetic nanoparticles exhibit a variety of unusual phenomena when compared to the bulk materials, particularly when the dimensions involved are comparable to critical magnetic length scales such as the exchange length(1,2). An open challenge is to build a consistent picture of the single-domain limit and of the particle size dependence of the spin arrangement close to the singleto multi-domain transition. A detailed analysis of such size-dependent transitions is difficult in magnetic measurements encompassing large particle ensembles since single-particle properties are masked by distributions of particle size, anisotropies and dissimilar local interactions with the underlying substrate.

In this work we combine x-ray magnetic circular dichroism (XMCD) with photoemission electron microscopy (PEEM) to study the magnetization orientation of single iron (Fe) particles with sizes ranging from 5 to 25 nm. We show that above a critical size of ~6 nm, the competition

of exchange interaction and anisotropy energy can lead to the formation of noncollinear spin structures in Fe nanoparticles coupled to a ferromagnetic cobalt substrate, while the magnetization of the smaller particles is aligned collinearly with that of the substrate(3). This transition can only be captured by quantitatively determining the magnetization orientation of individual nanoparticles. Numerical calculations indicate a sharp transition from an exchange-dominated to an anisotropy-dominated regime: the smaller particles are in a single-domain state with magnetization collinearly aligned to that of the substrate, while larger particles exhibit a static spin spiral analogous to an exchange spring(3). Our results demonstrate that unexpected spin arrangements at nanoscale interfaces can result from the balance between the particlesubstrate interaction and the individual properties of the particles. This knowledge is crucial for the development of novel devices which make use of nanoscale magnetic phenomena at interfaces.

(1)

J. Bansmann et al., “Magnetic and structural properties of isolated and assembled clusters”, Surf. Sci. Rep. 56, 189, (2005).

(2)

X. Batlle and A. Labarta, “Finite-size effects in fine particles: magnetic and transport properties”, J. Phys. D, 35, R15 (2002).

A. Fraile Rodríguez, A. Kleibert, J. Bansmann, A. Voitkans, L. J. Heyderman, and F. Nolting, “Size-dependent spin structures in iron nanoparticles”, Phys. Rev. Lett., 104, 127201 (2010).

(3)

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Realization of efficient LED’s emitting at 1,55 µm J.M Ramírez, O. Jambois, D. Navarro, S. Hernández, Y. Berencén, F. Ferrarese, A. Martínez, P. Pellegrino and B. Garrido Departament d’Electrònica, IN2UB, Universitat de Barcelona, Spain

One of the key challenges of Si photonics is the realization of an efficient Si-based light source. Silicon quantum dots (nanocrystals) embedded in amorphous silica matrices has been shown as promising material to achieve this goal. Due to quantum confinement, the radiative recombination as well as an enlargement of the band gap in Si is observed, allowing the emission in the visible range.

Moreover, it has been demonstrated that silicon nanocrystals act as efficient sensitizers for Erbium luminescence in silicon rich silicon oxide layers.(1) The enhanced luminescence at 1.55 µm is particularly interesting as it corresponds to the 3rd window of telecommunications.

This work deals with the excitation mechanisms and the optimization of the electroluminescence (EL) of such systems. For this, several materials were investigated.

Figure 1: Evolution of the EL with frequency at the visible range.

Two deposition techniques were used (plasma enhanced chemical vapour deposition, and low pressure chemical vapor deposition) to fabricate Er-doped Silicon rich silicon oxide. The silicon nanocrystals were formed after deposition by annealing the layers at high temperature (2).

The silicon excess was changed from 12%, up to 20%.

MOS capacitors were used to study the electrical transport and the electroluminescence.Power efficiencies from 1E-5 to 2E-2% were achieved in DC excitation.

The emission of these devices has been increased by the optimization of the stress voltage conditions. Working in AC mode and varying the frequency, the duty cycle and voltage of the input signal, improvement on this LED’s emission has been observed.

Figure 2: El from the erbium at 1,55 mm.

AJ Kenyon,” Evidence of energy coupling between Si nanocrystals and Er3+ in ion-implanted silica thin films”, Applied Physics, 75 (1999)

(1)

O. Jambois, ” Towards population inversion of electrically pumped Er ions sensitized by Si nanoclusters”, Optics Express, Vol. 18 Issue 3, pp.2230-2235 (2010)

(2)

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III Jornada In2UB - 13 Octubre 2010

Development of medicines in nanostructured surfactant systems M.J. García Celma Department of Pharmacy and Pharmaceutical Technology. Faculty of Pharmacy. University of Barcelona.

R+D Associated Unit to CSIC. Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN).

The design and development of new delivery systems to enhance the effectiveness of existing drugs and new biological molecules have an important role in pharmaceutical research. Delivering a drug precisely and safely to its target site at the right period of time to have a controlled release and achieve the maximum therapeutic effect remains a yardstick in the design and development of novel drug delivery systems. Nanocarriers have the possibility of providing endless opportunities in the area of drug delivery and therefore are increasingly being investigated to harness their potential. Nanocarriers, on account of their higher ratio of surface area to volume, show improved pharmacokinetics and biodistribution of therapeutic agents and thus minimize toxicity by their preferential accumulation at the target site. They can improve solubility of hydrophobic compounds and render them suitable for parenteral administration. Furthermore, they increase the stability of a variety of therapeutic agents, like peptides and oligonucleotides.

Surfactant systems appears in nanotechnological literature and patents as solubilisation and reaction media and they have potential applications as colloidal nanocarri-

ers for targeted drug delivery. In this presentation, the research activity of the group “Development of medicines in nanostructured surfactant systems” in the Faculty of Pharmacy will be presented. This research has been carried out in collaboration with the QCI/CSIC group, in the frame of CIBER-BBN. Among the nanostructured surfactant systems designed, the results obtained with microemulsions, nano-emulsions, highly concentrated emulsions, polymeric nanoparticles and meso/macroporous materials will be emphasized. Formation of nanoemulsions and highly concentrated emulsions can be achieved by low energy methods (1,2). One of the most interesting applications of these systems is their use as reaction media. Polymerization in the continuous and/ or dispersed phase leads to highly porous materials such as solid foams or to nanoparticles. The structure obtained can be controlled by composition parameters and the size and polidispersity of the materials obtained are dependent of the emulsion droplet size distribution and thus on the emulsification method2. Several drugs have been incorporated to the nanostructured surfactant systems developed and drug release kinetics have been determined (3,4).

N. Sadurní, C. Solans, N. Azemar, M.J. García-Celma, “Studies on the formation of O/W nano-emulsions, by low-energy emulsification methods, suitable for pharmaceutical applications”. European Journal of Pharmaceutical Sciences 26, 438-445 (2005).

(1)

J. Esquena, G.S.R. Ravi Sankar, C. Solans, “Highly concentrated W/O emulsions prepared by the PIT method as templates for solid foams” Langmuir 19, 2983-2988 (2003)

(2)

P. Izquierdo, J.W. Wiechers, E. Escribano, M.J. García-Celma, T.F. Tadros, J. Esquena, J.C. Dederen, C. Solans, “A study on the influence of emulsion droplet size on the skin penetration of tetracaine”. Skin Pharmacology and Physiology 20, 263-270 (2007).

(3)

G. Calderó, M. Llinàs, M.J. García-Celma, C. Solans, “Studies on controlled release of hydrophilic drugs from W/O high internal phase ratio emulsions”. Journal of Pharmaceutical Sciences 99 (2), 701-711 (2010).

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ABSTRACTS

Two dimensional microfluidics on circuits of wettability contrast Alba Pulido-Companys, Patricia Burriel, Jordi Ignés-Mullol, Josep Claret, and Francesc Sagués SOC and SAM group, Universitat de Barcelona, Departament de Química Física. Barcelona, Spain.

Inspired by the devices and achievements in the field of microfluidics, we present an experimental set-up that allows to control the flow of Langmuir monolayers through a circuit imprinted on a solid suport. The circuits are prepared on top of a brass plate, and consist on hydrophilic tracks embedded in a superhydrophobic surface (Fig. A).

An electroless silver deposit turns the surface hydrophilic.

A predesigned circuit pattern is imprinted during a soft litography process, and a self assembled monolayer (SAM) of a fluorinated thiol turns the surface surrounding the circuit track superhydrophobic (contact angle 170º).

The brass plate is mounted into a three-compartments Langmuir trough, and in each compartment a hydrophilic barrier and a Wilhelmy plate balance allow the control of monolayer flow and surface pressure. As an application of this device, we have measured the diffusion coefficient of a fluorescent probe dispersed in a DMPC monolayer coflowing with a pure DMPC monolayer through a rectilinear path on a water subphase (Fig. B).(1) As future developments it is planned to look for different mobilitymediated phenomena for species dispersed in monolayers, such as sorting, mixing or chemical reactions along the contact line, using a rectilinear as well as serpentine paths.

Figure A: Rectilinear circuit and picture of a water droplet on top of the superhydrophobic surface.

Figure B: Coflow of a monolayer containing a fluorescent probe and a pure DMPC monolayer through a rectilinear path.

P. Burriel, J. Ignés-Mullol, J. Claret, F. Sagués, “A two dimensional microfluidic device using circuits of wettability contrast “, Langmuir 26 (7), 4613-4615 (2010).

(1)

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III Jornada In2UB - 13 Octubre 2010

Development of medicines in nanostructured surfactant systems Javier Selva(1), Susana E. Martínez(1), David Buceta(2), María J. Rodríguez-Vázquez(2), M. Carmen Blanco(2), M. Arturo López-Quintela(2) and Gustavo Egea(1) (1) Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Instituts d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) i de Nanociències i Nanotecnologia (IN2UB), Universitat de Barcelona, E-08036 Barcelona, Spain (2) Laboratorio de Magnetismo y Nanotecnología (Nanomag), Instituto de Investigación Tecnológica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain. jselva@ub.edu

Silver atomic quantum clusters (AgAQCs), with two or three silver atoms, show electrocatalytic activities that are not found in nanoparticles or in bulk silver. AgAQCs supported on glassy carbon electrodes oxidize ethanol and other alcohols in macroscopic electrochemical cells in acidic and basic media. This electrocatalysis occurs at very low potentials (from ~ +200 mV vs RHE), at physiological pH, and at ethanol concentrations that are found in alcoholic patients. When mammalian cells are co-exposed to ethanol and AgAQCs, alcohol-induced alterations such as rounded cell morphology, disorganization of the actin cytoskeleton, and activation of caspase-3 are all prevented. This cytoprotective effect of AgAQCs

is also observed in primary cultures of newborn rat astrocytes exposed to ethanol, which is a cellular model of fetal alcohol syndrome. AgAQCs oxidize ethanol from the culture medium only when ethanol and AgAQCs are added to cells simultaneously, which suggests that cytoprotection by AgAQCs is provided by the ethanol electrooxidation meditated by the combined action of AgAQCs and cells. Overall, these findings not only show that AgAQCs are efficient electrocatalysts at physiological pH and prevent ethanol toxicity in cultured mammalian cells, but also suggest that AgAQCs could be used to modify redox reactions and in this way promote or inhibit biological reactions.

posters

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Cluster analysis approach to the phase transition of water in supercooled region Valentino Bianco and Giancarlo Franzese Departament de FĂ­sica Fonamental, Universitat de Barcelona

Water is a fundamental substance for all processes involving life. It has many unusual properties compared with other liquids. Recent studies of hydrated biomolecules and nanoconfined water suggest that, surprisingly, the anomalous properties of water are consistent with the hypothesis of the occurrence of first-order phasetransition between two liquids with diferent densities at low temperature and high pressure. In this hypothesis the phase transition line ends in a liquid-liquid critical point.

To validate this hypothesis experiments in nanoconfine-

ment could be very valuable, because the yallow to explore the water behavior in a region of temperature that would be other wise inaccessible for bulk liquid water, as a consequence of inevitable crystallization.

We present here a coarse-grained model of water that give insight in to the physics of a nanoconfined water monolayer. Our model allows us to analyze the possible existence of a critical point thanks to a mapping into a percolating model.

References K.Stokely, M.G.Mazza, H.E.Stanley, G.Franzese, Proc.Natl.Acad.Sci.U.S.A.107,1301-1306(2010).

G.Franzese, F.delosSantos, J.Phys.:Cond.Matt. 21504107 (2009).

M.G.Mazza, K.Stokely,E.G.Strekalova,H.E.Stanley, G.Franzese, ComputerPhys.Comunications180, 497-502(2009).

P.Kumar, G.Franzese and H.E.Stanley, Phys.Rev.Lett.100,105701 (2008).

G.Franzese, H.Stanley, J.Phys.:Cond.Matt.19, 205126 (2007).

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III Jornada In2UB - 13 Octubre 2010

Uniform large area colloidal self-assembled layers of silica submicron-particles by langmuir-blodgett technique Edgar Julián Cabrera, Sabine Portal and Enric Bertran FEMAN Group, Department of Applied Physics and Optics Institute Nanoscience and Nanotechnology, IN2UB, University of Barcelona.

Large areas nanopatterned surfaces have a raising interest in the fabrication of templates and thin membranes, biomedical sensors and for the next-generation photonic devices. Morphological and structural properties of twodimensional (2D) photonic crystal monolayers made up of silica particles. The silica submicron-particles of 230 nm diameter were produced by Stober sol-gel process with morphological, structural and very low size dispersion characteristics suitable to self-assemble them in closed-packed 2D crystal monolayers. Langmuir–Blodgett technique was used to deposit the nanometric silica particles on c-Si substrates. The resulting films consisted of a single monolayer of submicrometric particles arranged in a hexagonal compact structure. The monolayer

building characteristics of the particles were controlled by monitoring the surface pressure vs. surface area (Π-A) isotherm during the deposition process. Large area arrangement of the particles becomes critically depending of particles (low size dispersion and spherical shape), hence an accurate choice of submicron-particles is a key point to achieve it. The shape of the particles and the film structure and morphology were characterized by environmental scanning electron microscopy. Finally, the wettability of the monolayer was studied using the sessile drop method. The resulting monolayers show an arrangement extended to large areas in a close-packed structure.

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Combination of Electron Tomography and Electron Beam Precession applied to Sn precipitates in Al matrix JM. Rebled (1,2), Ll. Yedra (1), J. Portillo (3), S. Estradé (1,3) and F. Peiró (1) (1) LENS-MIND/IN2UB, Dept. d’Electrònica, Universitat de Barcelona, c/ Martí Franqués 1, 08028 Barcelona, CAT, Spain (2) Institut de Ciència de Materials de Barcelona, CSIC, 08193 Bellaterra, Catalonia, Spain (3) TEM-MAT, Serveis Cientificotècnics, Universitat de Barcelona, 08028, Barcelona, CAT, Spain

In nanoscience and nanotechnology, object size, shape and faceting are key features determining final functionality and behavior of the investigated nanomaterial, just as well its specific composition.

Tomography is a powerful tool to obtain 3D information from 2D projection images. In particular, tomography is an active field in materials science, where the possibility to combine both the scanning approach and high angle annular dark field detectors (STEM- HAADF Tomography) allows the acquisition of 2D images which display contrast variations due to atomic number in the object, and avoid the artifactual changes which appear while tilting the object due to diffraction contrast seen in conventional TEM (non-STEM) illumination.(1) More recently, new expectatives have been opened with the combination of tomography with electron diffraction (2,3,4) and electron precession5 in the field of electron crystallography.

In the present work we will combine the bright field imaging mode in TEM with both electron tomography and electron beam precession techniques in order to reconstruct the morphology of Sn precipitates embedded in a Al matrix. The tilt series was acquired in a range from +49º to -61º at intervals of 2º and with a precession angle of 0.6º. Our preliminary results clearly show the advantage of the precession technique to avoid the presence of artifacts due to diffraction and curvature contrast in the images (figure 1). As a drawback, we should remark that the images obtained with the precession system activated present a slightly blurred aspect due to the limitations in achieving optimum focusing conditions with our present instrumentation. Despite this, the images enabled to carry out a 3D reconstruction of the object.

FIG. 1.

Selected bright field images of a Sn precipitate into the Al matrix acquired at different angles without (a-d) and with precession (e-h), respectively, in conventional TEM mode.

P. A. Midgley et al., Journal of Microscopy, 223 (2006) 185 U. Kolb et al., Acta Crystallographyca, A63 (2007) s66 (3) U. Kolb et al., Ultramicroscopy, 107 (2007) 507 (4) U. Kolb et al., Ultramicroscopy, 108 (2008) 763 (5) E. Mugnaioli et al., Ultramicroscopy, 109 (2009) 758 (1) (2)

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III Jornada In2UB - 13 Octubre 2010

Magnetic deflagration in Gd5Ge4 S. Vélez (1), J. M. Hernàndez (1), A.Fernández (1), F. Macià (1), C. Magen (2), P. Algarabel (3), J. Tejada (1), and E.M. Chudnovsky (1,4) (1) Facultat de Física, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain (2) Instituto de Nanociencia de Aragón-ARAID, Universidad de Zaragoza, 50009 Zaragoza, Spain (3) Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, Universidad de Zaragoza and Consejo Superior de Investigaciones Científicas, 50009 Zaragoza, Spain (4) Physics Department, Lehman College, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589, USA

The field-induced the AFMFM magnetostructural transition in the intermetallic compound Gd5Ge4 occurs, in certain conditions, in an avalanche-like manner (Fig. 1).

In this work we have studied, using a large polycrystalline sample, whether the magnetic deflagration is responsible for the avalanches observed. The spontaneous appearance and the magnetic dynamics of these avalanches have been studied with different experimental techniques and under different conditions. We show that all the data

Figure 1: Isothermal (T = 2 K) magnetization curves of the Gd5Ge4 sample cooled in the presence of the magnetic field, HFC. At low HFC, when the initial state is mostly AFM, the magnetization changes in an avalanche-like process.

Avalanches occur only at low temperatures and high-fieldsweep rates. The inset shows the initial magnetization vs field, achieved in a FC process.

obtained fit well into the theoretical framework of magnetic deflagration1 with a speed of the flame in the range of 0.1-1.0 m/s (Fig. 2). This adds Gd5Ge4 to the growing family of materials (that now includes molecular magnets (2,3) and manganites(4) which exhibit this phenomenon. The novelty of the magnetic deflagration in Gd5Ge4 (5) is that the burning of the metaestable magnetic phase involves a magnetostructural transition alongside with the re-ordering of spins.

Figure 2: Ignition field dependence of the avalanche speed in the Gd5Ge4 sample for two different initial states (ZFC and FC at 10KOe). Avalanches were ignited at T=2 K. The inset shows the maximum measured temperature for each avalanche.

(1) D. A. Garanin and E. M. Chudnovsky, Phys. Rev. B 76, 054410 (2007).

(2) Y. Suzuki, M. P. Sarachik, E. M. Chudnovsky, S. McHugh, R. Gonzalez-Rubio, N. Avraham, Y. Myasoedov, E. Zeldov, H. Shtrikman, N. E. Chakov, and G. Christou, Phys. Rev. Lett. 95, 147201 (2005).

(3) A. Hernández-Mínguez, J. M. Hernandez, F. Macià, A. García- Santiago, J. Tejada, and P. V. Santos, Phys. Rev. Lett. 95, 217205 (2005).

(4) F. Macià, A. Hernández-Mínguez, G. Abril, J. M. Hernandez, A. García-Santiago, J. Tejada, F. Parisi, and P. V. Santos, Phys. Rev. B 76, 174424 (2007).

(5) S. Velez, J. M. Hernandez, A. Fernandez, F. Macià, C. Magen, P. Algarabel, J. Tejada, and E. M. Chudnovsky, Phys. Rev. B 81, 064437 (2010).