Single-chain magnet behavior in a finite linear hexanuclear molecule

The careful monitoring of crystallization conditions of a mixture made of a Tb^III building block and a substituted nitronyl-nitroxide that typically provides infinite coordination polymers (chains), affords a remarkably stable linear hexanuclear molecule made of six Tb^III ions and five NIT radicals. The hexanuclear units are double-bridged by water molecules but ab initio calculations demonstrate that this bridge is inefficient in mediating any magnetic interaction other than a small dipolar antiferromagnetic coupling. Surprisingly the hexanuclears, despite being finite molecules, show a single-chain magnet (SCM) behavior. This results in a magnetic hysteresis at low temperature whose coercive field is almost doubled when compared to the chains. We thus demonstrate that finite linear molecules can display SCM magnetic relaxation, which is a strong asset for molecular data storage purposes because 1D magnetic relaxation is more robust than the relaxation mechanisms observed in single-molecule magnets (SMMs) where under-barrier magnetic relaxation can operate.

A stable hexanuclear molecule made of a Tb^III building block and a substituted nitronyl-nitroxide radical show a single-chain magnet behavior despite being a finite molecule.     

meta-Substituted triphenylamines as new dyes displaying exceptionally large Stokes shifts

A straightforward synthesis of fluorescent tris-meta-substituted triphenylamines (m-TPAs) is presented. These new fluorophores display a unique feature that is a remarkably high Stokes shift up to 250 nm, as compared to their para counterparts. Although the meta substitution is made at the expense of the quantum yield, the latter is maintained at an appreciable level (5%) making the m-TPAs a new class of fluorophores adaptable to a large range of applications from biology to materials science.     

Homodyne detection readout for bit-oriented holographic memories

Homodyne detection is proposed to increase the readout signal of bit-oriented holographic memories. It can be easily implemented on present memory architectures by making the diffracted signal interfere with a reflection of the reading beam. The large resulting increase of the readout signal can be used to enhance the data transfer rate. A first experimental demonstration of such a readout procedure is presented.     

Simultaneous achievement of narrow pulse width and low pulse-to-pulse timing jitter in 1.3 microm passively mode-locked quantum-dot lasers

We have analyzed pulse width and timing jitter in passively mode-locked two-section InAs quantum-dot lasers emitting at 1310 nm and have identified two distinct, extensive mode-locked regions with robust short pulses and low timing jitter. A record combination of 2 ps pulses and 25 fs/cycle timing jitter (500 fs, 1-100 MHz), with 1 mW average output power per facet, is demonstrated.     

The structure of unicellular maps, and a connection between maps of positive genus and planar labelled trees

A unicellular map is a map which has only one face. We give a bijection between a dominant subset of rooted unicellular maps of given genus and a set of rooted plane trees with distinguished vertices. The bijection applies as well to the case of labelled unicellular maps, which are related to all rooted maps by Marcus and Schaeffer’s bijection. This gives an immediate derivation of the asymptotic number of unicellular maps of given genus, and a simple bijective proof of a formula of Lehman and Walsh on the number of triangulations with one vertex. From the labelled case, we deduce an expression of the asymptotic number of maps of genus g with n edges involving the ISE random measure, and an explicit characterization of the limiting profile and radius of random bipartite quadrangulations of genus g in terms of the ISE.     

Decay of Solutions to a Linear Viscous Asymptotic Model for Water Waves

The authors discuss a linear viscous asymptotic model for water waves and the decay rate of solutions towards the equilibrium.     

Collective increase of first impression bias

We propose a simple model of first impression bias (FIB), where agents tend to ignore features which contradict their initial view. We consider a population of agents which are all in contact with a media, communicating randomly chosen features of an object. In some cases, we observe on simulations that FIB is significantly more frequent when the agents interact with each other than when they are only in contact with the media. We design an analytical aggregated model of the global agent‐based model behavior, which helps to explain the higher number of FIB due to the interactions. © 2009 Wiley Periodicals, Inc. Complexity, 2010     

Congested traffic dynamics, weak flows and very degenerate elliptic equations

Starting from a model of traffic congestion, we introduce a minimal-flow-like variational problem whose solution is characterized by a very degenerate elliptic PDE. We precisely investigate the relations between these two problems, which can be done by considering some weak notion of flow for a related ODE. We also prove regularity results for the degenerate elliptic PDE, which enables us in some cases to apply the DiPerna–Lions theory.     

Vapor‐Phase Linker Exchange of the Metal–Organic Framework ZIF‐8: A Solvent‐Free Approach to Post‐synthetic Modification

Zeolitic imidazolate frameworks (ZIFs) are a sub‐class of metal–organic frameworks (MOFs). Although generally stable, ZIFs can undergo post‐synthetic linker exchange (PSLE) in solution under mild conditions. Herein, we present a novel, solvent‐free approach to post‐synthetic linker exchange through exposure to linker vapor.     

Non-isothermal oxidation and kinetic analysis of pure magnesium powder

Journal of Thermal Analysis and Calorimetry - With high energy densities, metals appear as innovative energy carriers. In the present study, magnesium powder is considered as fuel for energy...