New magnetic organic–inorganic composites based on hydrotalcite-like anionic clays for drug delivery

The structural “memory effect” of anionic clays was used to obtain layered double hydroxides (LDHs) with tailored magnetic properties, by loading iron oxides and/or spinel structures on iron partially substituted hydrotalcite-like materials. The obtained magnetic layered structures were further used as precursors for new hybrid nanostructures, such as aspirin–hydrotalcite-like anionic clays. Transmission electron microscopy (TEM) analysis shows that small iron oxide or spinel nanoparticles coexist with the fibrous drug particles on the surface of partially aggregated typical clay-like particles. The specific saturation magnetization of the loaded LDHs can be increased up to 70 emu/g by using specific post-synthesis treatments.     

Do Bosons Condense in a Homogeneous Magnetic Field?

It has been known since the paper⁽²⁶⁾ and then due to a rigorous result⁽³⁾ that the answer to the question in the title is negative for a three-dimensional “ideal gas of charged bosons”. The present paper adds a new rigorous result in this direction. We show that the answer to the question becomes positive, if this “ideal gas of charged bosons” is simultaneously embedded in an appropriate periodic external potential. We prove that it is true for the Perfect Bose Gas (PBG), as well as for the Imperfect Bose Gas with a Mean-Field repulsive particle interaction.     

Spiraling attractors and quantum dynamics for a class of long-range magnetic fields

We consider the long time behavior of a quantum particle in a 2D magnetic field which is homogeneous of degree −1. If the field never vanishes, above a certain energy the associated classical dynamical system has a globally attracting periodic orbit in a reduced phase space. For that energy regime, we construct a simple approximate evolution based on this attractor, and prove that it completely describes the quantum dynamics of our system.     

Dynamics of H2O and Na+ in nafion membranes

We investigate the transport properties of a model of a hydrated Na-Nafion membrane using molecular dynamics simulations. The system consists of several Nafion chains forming a pore with the water and ions inside. At low water content, the hydrophilic domain is not continuous and diffusion is very slow. The diffusion coefficient of both water and Na+ increases with increasing hydration (more strongly so for Na+). The simulations are in qualitative agreement with experimental results for similar systems. The diffusion coefficient is an average over the motion of ions or water molecules located in different environments. To better understand the role of the environment, we calculate the distribution of the residence times of the ion (or water) at different locations in the system. We discuss the transport mechanism in light of this information.     

Evidence,by metastable quenching spectroscopy,that CO adsorbs on K/Ni(111) near potassium and lies flat or tilts when heated

By using metastable quenching spectroscopy (MQS) we show that if a K/Ni(111) surface with low K coverage (θ_K = 0.1 and 0.12) is exposed to low doses of CO (0.3 L), the CO molecules are adsorbed near the potassium atoms. Heating from 118 to 298 K results in spectral changes that indicate that the CO molecules closest to the potassium atoms tilt strongly or lie flat on the surface.     

Preface: special topic section on photochemistry at surfaces

This Special Topic Section on Photochemistry at Surfaces contains invited essays by several leading scientists in the field. These essays present personal perspectives on the field and provide an overview of promising areas for future research on photo-initiated processes at surfaces using advanced experimental techniques. The authors focus on fundamental aspects of the field, which also has significant future applications in photovoltaic solar cells and photocatalytic water splitting.     

Memory Effects in Non-Interacting Mesoscopic Transport

Consider a quantum dot coupled to two semi-infinite one-dimensional leads at thermal equilibrium. We turn on adiabatically a bias between the leads such that there exists exactly one discrete eigenvalue both at the beginning and at the end of the switching procedure. For a specific adiabatic limit scenario, it is shown that the expectation in the final bound state strongly depends on the history of the switching procedure. On the contrary, the contribution to the final steady-state corresponding to the continuous spectrum has no memory, and only depends on the initial and final values of the bias.     

The interaction of oxygen and potassium on the Ru(001) surface

The interaction of oxygen and different coverages of potassium on Ru(001) has been investigated by thermal desorption spectroscopy (TDS), metastable quenching spectroscopy (MQS), electron stimulated desorption spectroscopy (ESD), and work-function change measurements. The results show that this is a complex surface system with several different oxides forming, depending on the surface stoichiometry and temperature. While we cannot uniquely identify all the surface species, our interpretation of the present data combined with previous information is as follows. For potassium coverages up to about three monolayers (θ_K ≈ 1), exposure to oxygen initially gives oxygen atoms on the surface. Further exposure produces some surface monoxide ions O²⁻, which are converted with additional exposure to Superoxide ions O⁻₂ and possibly peroxide ions O²⁻₂. Thermal annealing causes strong changes in the surface oxide composition, and with potassium multilayers (θ_K ≈ 10) all the oxides diffuse beneath the K surface layer with annealing to only 300 K. K₂O and K₂O₂ are found to desorb together in the 600–700 K region.     

A new geometry for field enhancement in surface-enhanced spectroscopy

We present calculations that indicate that for well-chosen materials a system consisting of a small sphere (diameter ?400 Å) suspended above a planar surface, is a good laser intensity amplifier and an interesting candidate for surface-enhanced spectroscopy. Use of SiC and doped InSb extends the frequency range of surface-enhanced spectroscopy to the infrared (≈200 to ≈1100 cm^?1).