315 research outputs found
INVESTIGATION OF MORPHOLOGICAL AND STRUCTURAL PROPERTIES OF IONIC LIQUID THIN LAYERS ON SOLID SURFACES BY SCANNING PROBE MICROSCOPY
No full textMolten salts attracted the attention of the scientific community several times during the last century. This interest is motivated by the physico-chemical properties of these systems. In fact, usually molten salts show chemical and thermal stability, i.e. they do not easily decompose or react. Furthermore, these compounds remain liquid over an extended range of temperatures, in which they show also a remarkably low volatility. The fact that molten salts are composed solely by ions, and can have a quite wide electrochemical window, make them very interesting as electrolytes[1].
The main disadvantage in the usage of molten salts in any practical process, is their high melting point (for example as high as 800°C for NaCl), which severely limits the number of reactions that can be done in these media and reduces the possibility of industrial scaling, due to the high energy required to maintain those high temperatures. Since the '70s lower temperature molten salts has been synthesised, like chloroaluminate eutectic mixtures, having melting points around 100°C or even lower, but the real turning point that boosted the research field has been the development of the first water-stable low melting point molten salts, that is what are now usually named room temperature ionic liquids, or simply ionic liquids.
Ionic liquids are usually composed by a big organic cation and a bulky inorganic, water stable, anion: the bulkiness and the complex asymmetric structure of the ions prevent an efficient packaging, leading to a lowering of the coulombic cohesive energy and so of the melting point.
Ionic liquids maintain all the characteristics of the high temperature molten salts, but they are usually liquid at room temperature. This fact induced a renewed interest in the field, as is proved by the several thousand papers published on the topic in 2011.
The community of chemists devoted a great effort to the study of ionic liquids, because of the potential use of those liquids as solvents. Ionic liquids are complex systems, that usually are organised in polar and apolar domains, and can dissolve both polar and apolar species. In addition, there are virtually unlimited choices of ions, and each choice changes the physico-chemical characteristics of the systems: this allows to tailor the properties of the ionic liquids (like miscibility, density, viscosity...), in order to match specific tasks. The characteristics of ionic liquids, last but not least their low vapour pressure, promote them as good solvents for the growing field of the Green Chemistry, in substitution of the volatile organic compounds.
Ionic liquids are also promising as lubricants, in particular in micro- and nano- -electromechanical devices (NEMSs and NEMSs)[2, 3] as well as electrolytes in photoelectrochemical devices used for energy storage and energy production such as supercapacitors[4, 5] or Grätzel solar cells[6]. In all these cases, the most relevant processes determining the performance of the devices, take place at the liquid/solid interface between ILs and solid surfaces: this is a region only a few nanometers thick where the properties of ILs can be significantly different from those of the bulk. The investigation of the interfacial properties of ILs is therefore of primary importance for their technological exploitation. To date, the (bulk)liquid-vapour and solid- (bulk)liquid ILs interfaces have been studied, mostly by sum-frequency generation spectroscopy[7, 8] and by X-ray photoemission spectroscopy[9]. For imidazolium-based ILs, ordering of the ions at the solid/liquid or liquid/ vapour interface has been inferred from vibrational spectroscopy data. For example Mezger et al.[10] performed a study of the (bulk)liquid/solid interface between a negatively charged sapphire substrate and imidazolium and pyrrolidinium-based ILs. They found strong interfacial layering, with repeated spacing of 0.7-0.8 nm, decaying exponentially into the bulk liquid. Recently the ionic liquid/solid interface has been studied with the surface force apparatus (SFA)[11, 12, 13]. In those experiments thin layers of ionic liquids are compressed between two approaching sheets of mica, while the normal force is recorded. The force vs. distance curves show a characteristic oscillatory profile, extending for few nanometers from the interface and exponentially decaying into the bulk.
Only very recently, in order to explore in details the ionic liquid/solid interfaces, more local approaches has been used, i.e. scanning probe microscopies and numerical simulations. Layering at the solid/(bulk)liquid have been found by Atkin[14, 15] performing force spectroscopy with atomic force microscope (AFM). In these kind of measurements, in which the AFM tip is ramped against the interface while measuring the force acting on it, as in SFA experiments, subsequent ruptures of solvation layers are seen, beginning few nanometers above the surface. The group of Atkin, in collaboration with other groups, performed also scanning tunneling microscopy (STM)/AFM study on ionic liquid/Au(111) interface, finding a dependence of the behaviour of the solvation layers upon potential changes[16].
In simulation studies is again evidenced the formation of strong interfacial layering on different surfaces[17, 18], where moreover, the preferential orientation of the ions at the interface can be analysed.
The studies previously cited about the interfacial behaviour of the ionic liquids, are mainly focused to the analysis of the bulk ionic liquid/solid interface. To date, a little effort has been devoted to what happens when thin layers of an ionic liquid are put in contact with a solid substrate. In those kind of situations, where the surface/volume ratio is high, it can been argued that the interaction with the surface can greatly change the physico-chemical and structural properties of the ionic liquid. The study of systems with high surface/volume ratio is directly relevant in all those applications in which a thin _lm of ionic liquid is used, e.g. in tribological applications, as well as in
photoelectrochemical devices, where the liquid is soaked into a nanoporous matrix: a change of the properties of the ionic liquid in this case can heavily modify the final performance of the devices.
My PhD work has been devoted to improving further extend the understanding of the behaviour of thin films of ionic liquids in contact with solid surfaces. At the time when I begun my work, very few studies regarding such systems were published. A pioneering study on thin _lm of [Bmim][PF6] on mica has been published in 2006 by Liu et al.[19]. In this work, performed using an AFM, the ionic liquid has been found to structure in two different ways on substrate: as droplets and as at layers, qualitatively referred to as solid layers. Inspired by the approach of Liu, I decided to study more quantitatively the thin-layer/solid interface, in particular using atomic force microscopy, because this instrument can acquire morphologies with vertical sub-nanometer and lateral nanometric resolution, so giving access to very localised information. Furthermore other kind of maps regarding different physico-chemical properties can be acquired simultaneously to the topography and moreover, force spectroscopy studies can be performed ramping the AFM tip against the surface.
In particular I focused my investigation on the interaction of [Bmim][Tf2N], a hydrophobic and almost water-stable liquid, with different substrates, i.e. mica, amorphous silica, single crystal silicon covered by its native oxide, and HOPG graphite. The main part of the work has been performed on those test substrates, because their properties are well known and because they are at, so very suitable for an accurate AFM investigation. With the experience gained on those systems and the results obtained, on the last part of my PhD, the attention has been moved to surfaces more relevant for applications, as the nanostructured silicon oxide, directly synthesised in our lab with supersonic cluster beam deposition (SCBD).
In order to perform my investigation, I first obtained very thin ionic liquid layers on the surface, diluting the liquid into a solvent, (methanol, ethanol, chloroform), and then drop-casting few μl of the solution onto a freshly cleaned substrate, letting the evaporation to proceed in air. On all the insulating surfaces studied, the [Bmim][Tf2N] coexists in 2 forms: as liquid micro- and nano- droplets and in at ordered domains. The melting temperature of this particular ionic liquid is ~-4°C, so a fundamental role in the liquid to solid transition has to be played by the interaction with the solid surface. The solid-like terraces appear as at layers, often growing one on top of the other. The hypothesis is that each layer is composed by several layers of cations and anions. By a statistical analysis of the morphological maps acquired, I extrapolated that the height of the best sub-multiple of the solid-like terraces is δ=0.6nm, in good agreement with the result of the simulations.
The AFM has also been used to study the mechanical behaviour of the solid-like structures. If imaged in contact mode, the layers tend to be eroded after repeated scans, and in some cases the terraces are removed one by one, as in a lamellar solid. Investigating the resistance to normal loads, saw tooth profiles in force vs. separation curves have been found, highlighting a sequence of ruptures, separated by 1.8-2nm, where the average rupture pressure is ~2-3KBar, very similar to the maximum pressure found in a MD simulation of a tip penetrating in 4nm of [Bmim][Tf2N] on silica[20]. Moreover, the observation that supported IL islands were not disrupted by intense electric fields up to 108-109V/m (applied biasing the AFM with respect to sample during imaging) and that Scanning Nanoscale Impedance Microscopy[21] measurements highlighted a dielectric insulating character of the ordered domains (εr = 3-5 was measured[22]) is consistent with the idea
that IL ordered domains behave as solid materials in which the ions are tightly bound.
To understand what is the influence of the nanostructure on the formation of the solid-like layers, I realised [Bmim][Tf2N] depositions on nanostructured silica deposited on oxidised silicon by SCBD in our lab. Of particular interest is the case of IL coating on a sub-monolayer deposition of silica nanoparticles. The preliminary results show that the presence of a dense distribution of nanoparticles on the surface of oxidised silicon actually doesn't prevent the growth of multilayered solid-like domains, that are as thick as on at surfaces and densely distributed. The liquid part of the deposition is pinned to the silica clusters, fact that evidences the strong affinity of [Bmim][Tf2N] with silica. The results suggest that the formation of immobilised, possibly solid-like, layers of ionic liquids in contact with nanoporous matrices, is not unlikely and such structures and can strongly affect the properties of the devices in which those interfaces are present. This possibility is also supported by the fact that a small percentage of silica nanoparticles (5 wt%) is enough to induce the gelation in an IL-based electrolyte used for dye sensitised solar cells[23].
The findings of my PhD work highlight the potentialities of scanning probe techniques for the quantitative investigation of the interfacial properties of thin ionic liquid films. My AFM investigation highlights how heterogeneous can be the IL/solid interfaces and so how is of fundamental importance to deal with local and not with average properties. The results of my work show that the behaviour of thin layers of ionic liquid is greatly modified by the influence of the substrate. In particular, I found a coexistence of liquid domains and terraces with elevated structural order. The formation of those structures, not present in the bulk liquid, is clearly induced by the contact with the solid surface. The solid-like terraces are very resistant to normal loads and to intense electric fields and, differently from the bulk, they tend to behave as insulating layers: the development of those structures can then have a crucial influence in the performances of photoelectrochemical devices.
The importance of this field of research and the validity of my work, are witnessed by the increasing number of papers studying thin ionic liquid layers appeared just before, but especially during the course of my PhD[24, 25, 26, 27, 28, 15, 16]; in many of these works, the AFM is the instrument of choice for the interfacial investigation because it allows to access to the physico-chemical properties of the system with nanometric or sub-nanometric resolution in all the three dimensions.
In the next future the structural behaviour of the ionic liquids in contact with nanostructured surfaces will be further studied, making use of the experience of our group in synthesise the nanostructured oxides and metals. Moreover, we will explore in more details the dielectric properties of thin fillm of ionic liquids, in particular selecting those ILs directly used in supercapacitors and solar cells. Another interesting field that to date is still poorly explored is the interaction of ionic liquids with biological tissue. For this reason, we are going to begin to study the effects of ionic liquids on supported lipid bilayers.
Bibliography
[1] Wilkis, J. S., Green Chem 4, 73-80, (2002).
[2] Qu, J., Truhan, J. J., Dai, S., Luo, H., Blau, P., J. Tribol. Lett. 22, 207-214, (2006).
[3] Bhushan, B., Palacio, M., Kinzig, B., J. Coll. and Inter. Sci. 317, 275-287, (2008).
[4] Simon, P. and Gogotsi, Y., Nature Materials 7, 845-854, (2008).
[5] Appetecchi, G. B., Montanino, M., Carewska, M., Moreno, M., Alessandrini and F., Passerini, S., Electrochimica Acta 56, 1300-1307, (2011).
[6] Grätzel, M., Journal of Photochemistry and Photobiology A: Chemistry 164, 3-14, (2004).
[7] Santos, C. S., Baldelli, S., J. Phys. Chem. B 111, 4715-4723, (2007).
[8] Rollins, J. B., Fitchett, B. D. and Conboy, J. C., J. Phys. Chem. B 111, 4990-4999, (2007).
[9] Lovelock, K. R. J., Villar-Garcia, I. J., Maier, F., Steinrück, H. and Licence, P., Chem. Rev. 110, 5158-5190, (2010).
[10] Mezger, M., Schröder, H., Reichert, H., Schramm, S., Okasinski, J. S., Schöder, S., Honkimäki, V., Deutsch, M., Ocko, B. M., Ralston, J. And Rohwerder, M., Science 322, 424428, (2008).
[11] Ueno, K., Kasuya, M., Watanabe, M., Mizukami, M. and Kurihara, K., Phys. Chem. Chem. Phys. 12, 4066-4071, (2010).
[12] Perkin, S., Albrecht, T. and Klein, J., Phys. Chem. Chem. Phys. 12, 1243-1247 (2010).
[13] Min, Y., Akbulut, M., Sangoro, J. R., Kremer, F., Prudhomme, R. K. and Israelachvili, J., J. Phys. Chem. C 37, 16445{16449, (2009).
[14] Atkin, R. and Warr, G. G., J. Phys. Chem. C, 111, 5162-5168, (2007).
[15] Hayes, R., Warr, G. G. and Atkin, R., Phys. Chem. Chem. Phys. 12, 1709-1723, (2010).
[16] Atkin, R., Borisenko, N., Drüschler, M., El Abedin, S. Z., Endres, F., Hayes, R., Huber, B. and Roling, B., Phys. Chem. Chem. Phys. 13, 6849-6857, (2011).
[17] Sieffert, N., and Wip_, G., J. Phys. Chem. C 112, 19590-19603 (2008).
[18] Sha, M., Zhang, F., Wu, G., Fang, H., Wang, C., Chen, S., Zhang, Y., and Hu, J., J. Chem. Phys. 128, 134504, (2008).
[19] Liu, Y., Zhang, Y., Wu, G. and Hu, J., J. Am. Chem. Soc. 128, 7456-7457, (2006).
[20] Ballone, P., Del Pópolo, M. G., Bovio, S., Podestà, A., Milani, P. and Manini, N., Phys. Chem. Chem. Phys. in press (2011) (arXiv:1101.5424v1).
[21] Cassina, V., Gerosa, L., Podestà, A., Ferrari, G., Sampietro, M., Fiorentini, F., Mazza, T., Lenardi, C. and Milani, P., Phys. Rev. B 79, 115422, (2009).
[22] M. Galluzzi, Study of morphological and dielectric properties of thin ionic liquid films by Atomic Force Microscopy, Master Thesis, University of Milan, (2010).
[23] Wang, P., Zakeeruddin, S. M., Compte, P., Exnar, I. and Grätzel, M., J. Am. Chem. Soc., 125, 1166{1167, (2003).
[24] Cremer, T., Killian, M., Gottfried, J. M., Paape, N., Wasserscheid, P., Maier, F. and Steinrück, H.-P., Chem. Phys. Chme. 9, 2185-2190, (2008).
[25] Cremer, T., Stark, M., Deyko, A., Steinrück, H.-P. and Maier, F., Langmuir 27, 3662-3671, (2011).
[26] Yokota, Y., Harada, T. and Fukui, K., Chem. Commun. 46, 8627-8629, (2010).
[27] Zhang, F., Sha, M., Ren, X., Wu, G., Hu, J. and Zhang, Y., Chin. Phys. Lett. 27, 086101, (2010).
[28] Kaisei, K., Kobayashi, K., Matsushige, K., Yamada, H., Ultramicroscopy 110, 733-736, (2010)
Crystal structure of 4-(6-chloropurin-9-yl)-3-phenyl-4,5,6,6a-tetrahydro-3aH-cyclopenta[d]isoxazol-6-ol, C17H14N5O2Cl
No full textThe title compound crystallizes in the space group Pna21, with a = 10.124(5), b = 14.335(3), c = 11.113(2) Å. There is no conjugation between the purine moiety and the cyclopentane ring, whereas there is some conjugation between the isoxazoline and the phenyl rings. The chiral centers C3a, C4, C6a, C6 are either S, S, R, R or R, R, S, S respectively, because of the glide planes. The molecules are linked by intermolecular hydrogen bonds and van der Waal's forces
Bap. Gvarini ivnior. in fvnere Aloysii Esten. Principis jllvstriss. et S. R. E. Card. ampliss. oratio.
No full text"Habita Ferrariae in Sacra Principis aede XIII. Kl. Feb. M.D.LXXXVII"--P. 13.Includes two poems by Girolamo Bovio, on B4v.Woodcut armorial title-vignette, head- and tail-piece and pictorial initial.Signatures: A-B⁴.Mode of access: Internet.Bound with: Oratione consolatoria di M. Alberto Lollio (SPECIAL 94-B8232)
Innovative method for damage identification and structural health monitoring based on vibration measurements
No full text[ITALIANO] Scopo della tesi è presentare una nuova metodologia, appartenente al campo dei Controlli Non Distruttivi, e basata su misure di vibrazioni, sviluppata dall’autore presso il Dipartimento di Progettazione Aeronautica dell’Università degli Studi di Napoli “Federico II”. Scopo della ricerca è stato sviluppare una tecnica di controllo non distruttivo che soddisfacesse la maggior parte dei requisiti necessari allo sviluppo di un sistema di Health Monitoring (monitoraggio dello stato di salute di una struttura), riducendo nel contempo la complessità sia dell’algoritmo di analisi dei dati sia della strumentazione necessaria per l’acquisizione degli stessi.
La tecnica proposta è basata sulla acquisizione e sul confronto delle Funzioni di Risposta in Frequenza (FRF) della struttura monitorata, prima e dopo che un qualsivoglia danno insorga. Per effetto di un danneggiamento strutturale si viene a modificare il comportamento dinamico della struttura in termini di massa, rigidezza e smorzamento, e, conseguentemente, si avrà una variazione delle Funzioni di Risposta in Frequenza relative alla struttura danneggiata rispetto a quelle ricavate dalla struttura integra. Il metodo è quindi in grado di rilevare l’insorgere di un danneggiamento (identificazione), localizzarne la posizione (individuazione), ed indicarne l’eventuale accrescimento e propagazione (quantificazione). Ai fini della valutazione quantitativa della variazione tra le Funzioni di Risposta in Frequenza della struttura integra e di quella danneggiata è stato definito un indice detto “del danno”, il quale fornisce direttamente la misura dell’eventuale presenza del danneggiamento strutturale.
La sopra citata metodologia è stata applicata su di un pannello reale di fusoliera di un MD11, su di un pannello realizzato in materiale composito di tipo aeronautico, e su di un velivolo ATR-72.
È stato sviluppato inoltre un algoritmo di Reti Neurali al fine di ottenere un metodo di apprendimento basato sulla ricognizione. Questa tecnica di apprendimento consente di addestrare la rete neurale rendendola in grado di riconoscere solo gli esempi “positivi”, scartando, di conseguenza, quelli “negativi”. Nell’ambito di un controllo non distruttivo di una struttura un esempio “positivo” rappresenta uno stato di “salute” del componente strutturale analizzato, e, ovviamente, un esempio “negativo” rappresenta uno stato “danneggiato” dello stesso. Sulla base di questo obiettivo le reti neurali sono state addestrate facendo uso delle stesse FRF, relative alle strutture “sane”, impiegate per la determinazione degli Indici del Danno.
Con riferimento al danno: corrosione, danneggiamento di rivetti di collegamento, cricche, impatti su strutture ed altre tipologie di danneggiamenti sono stati indotti sugli articoli di prova.
Relativamente al sistema di eccitazione e sensoristica, dispositivi magnetostrittivi sono stati impiegati quali attuatori, e piastrine piezoceramiche in qualità di attuatori e sensori. Inoltre è stato impiegato, per l’acquisizione delle FRF, anche un sistema di vibrometria laser a scansione. Queste tecniche consentiranno lo sviluppo di un sistema di Health Monitoring automatico in grado di identificare danni strutturali in tempo reale, aumentando l’affidabilità strutturale e riducendo i costi di manutenzione. / [ENGLISH] The purpose of the thesis is to present an innovative application within the Non Destructive Testing field based upon vibration measurements developed by the author at the Department of Aeronautical Engineering of the University of Naples “Federico II” (Italy). The aim of the research has been to develop a Non Destructive Test (NDT) which meets most of the mandatory requirements for effective health monitoring systems while, at the same time, reducing as much as possible the complexity of the data analysis algorithm and the experimental acquisition instrumentation.
This proposed new method is based upon the acquisition and comparison of the Frequency Response Functions (FRFs) of the monitored structure before and after a damage occurs. Structural damage modifies the dynamic behaviour of a structure affecting its mass, stiffness and damping and consequently the FRFs of a damaged structure, when compared with the FRFs of a sound structure, makes the identification, localization and quantification of structural damage possible.
The activities presented in this thesis focus mainly on a new FRFs processing technique based upon the determination of a representative “Damage Index” for identifying and analysing damage on real-scale aeronautical structural components, such as large-scale fuselage reinforced panels, on aeronautical composite panels and on a real ATR-72 aircraft.
Furthermore, a dedicated neural network algorithm has been elaborated aimed at obtaining a “recognition-based learning” method. This kind of learning methodology permits us to train the neural network in order to enable it to recognise only “positive” examples and consequently discarding “negative” ones. Within the structural NDT a “positive” example means a “healthy” state of the analysed structural component and, obviously, a “negative” example means a “damaged” or perturbed state. With this objective in mind the neural network has been trained to make use of the same FRFs of the healthy structure used in determining the Damage Index.
Regarding damage, corrosion, failure of linking rivets, simple cracks, impacts on structure and other kind of damage have been induced on the test articles.
From an architectural standpoint, magnetostrictive devices have been tested as actuators, and piezoceramic patches as actuators and sensors. Besides it has been used a laser-scanning vibrometer system to acquire the FRFs. These techniques promise to bring us a step forward in the implementation of an automatic “health monitoring” system which will be able to identify structural damage in real time thereby improving safety and reducing maintenance costs
Crystal structures of 2,4,9-trimethyl-(3ar,4c,9c,9ac)-3a,4,9,9a-tetrahydrobenzo[f]isoindole-1,3-dione(endo), C15H17NO2 (1), and 2-methyl-(3ac,9ac)-3a,4,9,9a-tetrahydro-4r,9c-ethanobenzo[f]isoindole-1,3-dione(endo), C15H15NO2
No full textThe title compd. 1 is triclinic, space group P1, with a 7.198(2), b 7.965(2), c 12.707(2) Å, α 72.05(1), β 87.65(2), γ 65.18(2)° ; the title compd. 2 is orthorhombic, space group and Pbca, with a 8.156(3), b 13.177(3), c 22.742(4) Å. The chiral centers in both compds. C3a, C4, C9, C9a are either R, S, R, S or S, R, S, R (compd. 1) and either R, R, S, S or S, S, R, R (compd. 2) because of the centric space grou
Philosophical tributes: Between apathy and acknowledgment: (Rico Bovio-Pallares Ronquillo case, an historiographic commentary)
No full textIn this article we study a pair of collective books about a two Chihuahuan Philosophy professors, Enrique Pallares Ronquillo and Arturo Rico Bovio. Both recognized for their teaching and thought. However, some historiographical questions are unsolved through the main part of the chapters. How it can be described and understand the philosophical work of each one? Which is the social, political, intellectual and cultural context in which their philosophies were born and had been developed? Which connection had each acknowledgment book author with Pallares and Rico? In which way contribute both texts to nourishing the weak local philosophy’s memory
Homenajes filosóficos: entre la apatía y el reconocimiento (el caso Pallares Ronquillo-Rico Bovio, comentario historiográfico)
No full textResumen: En este trabajo se revisa el contenido de dos libros
de homenaje acerca de dos profesores chihuahuenses de
Filosofía: Enrique Pallares Ronquillo y Arturo Rico Bovio.
Ambos reconocidos por su labor pedagógica y sus ideas. Sin
embargo, existen varios cuestionamientos historiográficos que
quedan sin resolver a lo largo de la mayor parte de los capítulos.
¿Cómo ha de describirse y comprenderse el trabajo filosófico
de ambos?, ¿cuál es el medio político, social, intelectual y
cultural en el que surgieron y se desarrollaron sus filosofías?,
¿qué vínculo tiene cada autor, que participó en los libros de
homenaje, con Rico y Pallares?, ¿de qué manera contribuyen
ambos textos con la flaca memoria de la filosofía local?
Palabras clave: filosofía de la actualidad, filosofía del norte de
México, historiografía de la Filosofía, memoria, pensamiento
contemporáneo.
Abstract: In this article we study a pair of collective books
about a two Chihuahuan Philosophy professors, Enrique
Pallares Ronquillo and Arturo Rico Bovio. Both recognized for
their teaching and thought. However, some historiographical
questions are unsolved through the main part of the chapters.
How it can be described and understand the philosophical
work of each one? Which is the social, political, intellectual
and cultural context in which their philosophies were born
and had been developed? Which connection had each
acknowledgment book author with Pallares and Rico? In
which way contribute both texts to nourishing the weak local
philosophy’s memory?
Keywords: contemporary thought, historiography of
Philosophy, memory, Northern Mexican philosophy, today’s
philosophy
Homenajes filosóficos: entre la apatía y el reconocimiento (el caso Pallares Ronquillo-Rico Bovio, comentario historiográfico)
No full textResumen: En este trabajo se revisa el contenido de dos libros
de homenaje acerca de dos profesores chihuahuenses de
Filosofía: Enrique Pallares Ronquillo y Arturo Rico Bovio.
Ambos reconocidos por su labor pedagógica y sus ideas. Sin
embargo, existen varios cuestionamientos historiográficos que
quedan sin resolver a lo largo de la mayor parte de los capítulos.
¿Cómo ha de describirse y comprenderse el trabajo filosófico
de ambos?, ¿cuál es el medio político, social, intelectual y
cultural en el que surgieron y se desarrollaron sus filosofías?,
¿qué vínculo tiene cada autor, que participó en los libros de
homenaje, con Rico y Pallares?, ¿de qué manera contribuyen
ambos textos con la flaca memoria de la filosofía local?
Palabras clave: filosofía de la actualidad, filosofía del norte de
México, historiografía de la Filosofía, memoria, pensamiento
contemporáneo.
Abstract: In this article we study a pair of collective books
about a two Chihuahuan Philosophy professors, Enrique
Pallares Ronquillo and Arturo Rico Bovio. Both recognized for
their teaching and thought. However, some historiographical
questions are unsolved through the main part of the chapters.
How it can be described and understand the philosophical
work of each one? Which is the social, political, intellectual
and cultural context in which their philosophies were born
and had been developed? Which connection had each
acknowledgment book author with Pallares and Rico? In
which way contribute both texts to nourishing the weak local
philosophy’s memory?
Keywords: contemporary thought, historiography of
Philosophy, memory, Northern Mexican philosophy, today’s
philosophy
Surface Confinement Induces the Formation of Solid-Like Insulating Ionic Liquid Nanostructures
No full textWe
report on the modification of the electric properties of the
imidazolium-based [BMIM][NTf2] ionic liquid upon surface
confinement in the sub-monolayer regime. Solid-like insulating nanostructures
of [BMIM][NTf2] spontaneously form on a variety of insulating
substrates, at odds with the liquid and conductive nature of the same
substances in the bulk phase. A systematic spatially resolved investigation
by atomic force microscopy of the morphological, mechanical, and electrical
properties of [BMIM][NTf2] nanostructures showed that this
liquid substance rearranges into lamellar nanostructures with a high
degree of vertical order and enhanced resistance to mechanical compressive
stresses and very intense electric fields, denoting a solid-like character.
The morphological and structural reorganization has a profound impact
on the electric properties of supported [BMIM][NTf2] islands,
which behave like insulator layers with a relative dielectric constant
between 3 and 5, comparable to those of conventional ionic solids
and significantly smaller than those measured in the bulk ionic liquid.
These results suggest that, in the solid-like ordered domains confined
either at surfaces or inside the pores of the nanoporous electrodes
of photoelectrochemical devices, the ionic mobility and the overall
electrical properties can be significantly perturbed with respect
to the bulk liquid phase, which would likely influence the performance
of the devices
- …
