Newtonian Dynamics from the Principle of Maximum Caliber

The foundations of Statistical Mechanics can be recovered almost in their entirety from the principle of maximum entropy. In this work we show that its non-equilibrium generalization, the principle of maximum caliber (Jaynes, Phys Rev 106:620–630, 1957), when applied to the unknown trajectory followed by a particle, leads to Newton’s second law under two quite intuitive assumptions (both the expected square displacement in one step and the spatial probability distribution of the particle are known at all times). Our derivation explicitly highlights the role of mass as an emergent measure of the fluctuations in velocity (inertia) and the origin of potential energy as a manifestation of spatial correlations. According to our findings, the application of Newton’s equations is not limited to mechanical systems, and therefore could be used in modelling ecological, financial and biological systems, among others.     

Rapid access to ketones related to oleanolic and ursolic acids

We describe in this article a process with which to obtain different ketones related to oleanolic and ursolic acids from a natural source, Salvia canariensis L., with minimal use of chromatography columns. Amongst the isolated compounds was 12α-bromo-3-oxo-olean-13, 28-olide (3), which was fully characterised, including a characterisation of its molecular configuration by X-ray crystallographic analysis by 1 and 2-dimensional NMR techniques.     

Bidirectional Redox Molecular Switches: Electron-induced Cyclization and Cycloreversion Processes in Metacyclophanes

A reversible bidirectional ring-opening and ring-closing system triggered by electricity has been prepared by using metacyclophan-1-enes, a known thermo-photochromic molecular switch system.     

Controlling spin-spin network dynamics by repeated projective measurements

We show that coupled-spin network manipulations can be made highly effective by repeated projections of the evolving quantum states onto diagonal density-matrix states (populations). As opposed to the intricately crafted pulse trains that are often used to fine-tune a complex network's evolution, the strategy hereby presented derives from the "quantum Zeno effect" and provides a highly robust route to guide the evolution by destroying all unwanted correlations (coherences). We exploit these effects by showing that a relaxationlike behavior is endowed to polarization transfers occurring within a N-spin coupled network. Experimental implementations yield coupling constant determinations for complex spin-coupling topologies, as demonstrated within the field of liquid-state nuclear magnetic resonance.     

Computer-assisted study on the reaction between pyruvate and ylide in the pathway leading to lactyl–ThDP

In this study the formation of the lactyl-thiamin diphosphate intermediate (L-ThDP) is addressed using density functional theory calculations at X3LYP/6-31++G(d,p) level of theory. The study includes potential energy surface scans, transition state search, and intrinsic reaction coordinate calculations. Reactivity is analyzed in terms of Fukui functions. The results allow to conclude that the reaction leading to the formation of L-ThDP occurs via a concerted mechanism, and during the nucleophilic attack on the pyruvate molecule, the ylide is in its AP form. The calculated activation barrier for the reaction is 19.2?kcal/mol, in agreement with the experimental reported value.     

Synthesis and functionalization of new polyhalogenated BODIPY dyes. Study of their photophysical properties and singlet oxygen generation

A theoretical and experimental study on the iodination of BODIPY dyes with different degrees of substitution has been developed. Polyhalogenated BODIPYs synthesized in this work are the first examples of this type of dyes with more than two halogen atoms in the BODIPY core and they can be selectively functionalized. Surprisingly, the position in which halogen is attached has a marked effect in the photophysical properties and modulates the fluorescence capacity of the resulting BODIPY. These iodinated BODIPYs are efficient singlet oxygen generators.     

A new estimate on the indirect Coulomb energy

Here we prove a new lower bound on the indirect Coulomb energy in quantum mechanics, in terms of the single particle density of the system. The new universal lower bound is an alternative to the classical Lieb–Oxford bound (with a smaller constant, C = 1.45 < C_LO = 1.68) but involving an additive kinetic energy term of the single particle density as well. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Growth of stoichiometric and textured LiNbO3 films on Si by pulsed laser deposition

Laser ablation of single-crystal LiNbO₃ in a gas environment is used to grow films on (100) Si substrates heated to 650 °C. The film composition and crystallinity are studied as a function of the nature (reactive, O₂, or inert, Ar) and pressure of the gas environment applied during deposition and cooling-down processes, the laser energy density and the target–substrate distance. Experimental results show that a gas pressure close to 1 mbar is required to produce stoichiometric films in either O₂ or Ar. The modification of the laser energy density and the target–substrate distance allows us to improve the crystallinity of the films that become textured along the (006) direction. The influence of the experimental parameters on the film properties is discussed in the frame of the formation of a blast wave, that leads to the focusing of the expanding Li species and thus, to the increase of the Li content in the films. Received: 8 February 2001 / Accepted: 9 February 2001 / Published online: 3 May 2001     

Self-Organization and Leadership Emergence: A Cross-Cultural Replication

Project examined the cross-cultural generalizability of a model for leadership emergence based on the rugged landscape self-organization and the swallowtail catastrophe. Twelve groups of eight Chilean university students played the Island Commission game and rated each other on leadership behavior at the end of the one-hour activity. Analysis confirmed the replication of dynamical structure and critical points obtained previously from a U.S. sample.