Understanding the dependence on the pulling speed of the unfolding pathway of proteins

The dependence of the unfolding pathway of proteins on the pulling speed is investigated. This is done by introducing a simple one-dimensional chain comprising $N$ units, with different characteristic bistable free energies. These units represent either each of the modules in a modular protein or each of the intermediate "unfoldons" in a protein domain, which can be either folded or unfolded. The system is pulled by applying a force to the last unit of the chain, and the units unravel following a preferred sequence. We show that the unfolding sequence strongly depends on the pulling velocity $v_{p}$. In the simplest situation, there appears a critical pulling speed $v_{c}$: for pulling speeds $v_{p}v_{c}$ it is the pulled unit that unfolds first. By means of a perturbative expansion, we find quite an accurate expression for this critical velocity.Comment: accepted for publication in JSTA

Structure of the Vacuum in Deformed Supersymmetric Chiral Models

We analyze the vacuum structure of N=1/2 chiral supersymmetric theories in deformed superspace. In particular we study O'Raifeartaigh models with C-deformed superpotentials and canonical and non-canonical deformed Kahler potentials. We find conditions under which the vacuum configurations are affected by the deformations.Comment: 15 pages, minor corrections. Version to appear in JHE

La polémica en torno a La Perinola de Quevedo con un texto inédito

Este artículo repasa la polémica producida por la publicación, en 1632, del Para todos de Juan Pérez de Montalbán, y por la difusión, ese mismo año, de La Perinola de Quevedo, un mordaz ataque al texto de Pérez de Montalbán. Tras hacer un estado de la cuestión sobre los opúsculos manuscritos e impresos que se conocen en torno a dicha polémica, se analiza un manuscrito inédito, conservado en la Biblioteca Nacional de Madrid, atribuido al Padre Niseno, en el que se hace una defensa del Para todos y se ataca duramente La Perinola de Quevedo. This paper deals with the controversy produced as a result of the publication, in 1632, of Juan Pérez de Montalbán’s Para todos, and the diffusion that same year of Quevedo’s La Perinola, a bitter attack against Pérez de Montalbán’s book. This paper offers an appraisal of the libels, both manuscript and printed ones, involved in the polemics. It also offers and analysis of an unpublished manuscript, attributed to Father Niseno. This manuscript, kept at the National Library in Madrid, is a defense of Para todos, and a bitter attack on Quevedo’s La Perinola

El "jocoso numen" de sor Juana, desde la teoría de los géneros satíricos en el Renacimiento

Este trabajo analiza cómo los diferentes géneros satíricos cultivados por la autora mexicana sor Juana Inés de la Cruz (1648?-1695) entroncan con la práctica de los poetas de la Antigüedad clásica y de la Edad Moderna, así como con las discusiones teóricas que sobre los géneros satíricos se daban en el Renacimiento y el Barroco europeos. Para ello, se estudia, en primer lugar, la disponibilidad de estos textos en librerías y bibliotecas novohispanas del XVI, para analizar, después, ciertas marcas genéricas en los poemas de sor Juana que revelan un diálogo con dicha tradición clásica y moderna. The Mexican writer Sor Juana Inés de la Cruz (1648?-1695) used a variety of satirical genres in her poetry. This paper analyzes how her poetry ítems from the practice of Classical and Early Modern poets, as well as from the theoretical discussions on satire in Europe Turing the Reinsassancce and Baroque periods. This paper considers first the availability of these books in libraries and bookstores of 17th Century New Spain. It then offers an análisis of the generic features in Sor Juana’s poetry that reveal a dialogue with the Classical and Early Modern tradition

Thermal conductance of the water-gold interface: the impact of the treatment of surface polarization in non-equilibrium molecular simulations.

Interfacial thermal conductance (ITC) quantifies heat transport across material-fluid interfaces. It is a property of crucial importance to study heat transfer processes at both macro- and nanoscales. Therefore, it is essential to accurately model the specific interactions between solids and liquids. Here, we investigate the thermal conductance of gold-water interfaces using polarizable and non-polarizable models. Both models have been fitted to reproduce the interfacial tension of the gold-water interface, but they predict significantly different ITCs. We demonstrate that the treatment of polarization using Drude-like models, widely employed in molecular simulations, leads to a coupling of the solid and liquid vibrational modes that give rise to a significant overestimation of the ITCs. We analyze the dependence of the vibrational coupling with the mass of the Drude particle and propose a solution to the artificial enhancement of the ITC, preserving at the same time the polarization response of the solid. Based on our calculations, we estimate ITCs of 200 MW/(m2 K) for the water-gold interface. This magnitude is comparable to that reported recently for gold-water interfaces [279 ± 16 MW/(m2 K)] using atomic fluctuating charges to account for the polarization contribution

Orientation of Janus particles under thermal fields: The role of internal mass anisotropy.

Janus particles (JPs) are a special kind of colloids that incorporate two hemispheres with distinct physical properties. These particles feature a complex phase behavior, and they can be propelled with light by heating them anisotropically when one of the hemispheres is metallic. It has been shown that JPs can be oriented by a homogeneous thermal field. We show using multiscale simulations and theory that the internal mass gradient of the JPs can enhance and even reverse the relative orientation of the particle with the thermal field. This effect is due to a coupling of the internal anisotropy of the particle with the heat flux. Our results help rationalize previous experimental observations and open a route to control the behavior of JPs by exploiting the synergy of particle-fluid interactions and particle internal mass composition

Controlling local thermal gradients at molecular scales with Janus nanoheaters.

The generation and control of heat transport with nanoparticles is an essential objective of thermoplasmonics. Janus nanoparticles consisting of dissimilar materials with contrasting interfacial Kapitza conductance provide a route to control heat transport at the nanoscale. Here we use the recently introduced Atomistic Nodal Approach to map the surface temperature and Kapitza conductance of Janus nanoparticles to individual atoms. We show that the transition in the thermal transport properties between the hydrophobic and hydrophilic interfaces is exceptionally abrupt, occurring over length scales below 1 nm. We demonstrate the generality of this result using coarse-grained and all-atom models of gold nanoparticles. Further, we show how this behaviour provides a route to sustain significant temperature differences, on the order of tens of degrees for μW heat rates, between adjacent molecular layers attached to heated gold nanoparticles. Our work provides fundamental insight into nanoscale heat transport and a principle to design heterogeneous Janus nanoparticles for thermal transport applications