Correlation between shape and electronic states in nanostructures

We show how the electronic states of quantum wires and quantum dots can be evaluated exactly starting from the profile of the nanostructure observed by transmission electron microscopy, scanning tunneling microscopy and atomic force microscopy. The calculated quantization energies reproduce the energy position of the luminescence resonances in the optical spectra of different samples, without fitting parameters.     

A facile in situ microfluidic method for creating multivalent surfaces: toward functional glycomics

An in situ method of modifying the chemistry and topology of microfluidic surfaces in order to mimic the cellular environment is described. The binding of functionalised microbeads to microfluidic channels allows the surface-to-volume ratio of the system, and thus the number of biomolecules available for reaction, to be vastly increased, thereby enhancing the sensitivity of biochemical analyses. The sensitivity and specificity of the technique were first investigated via the study of carbohydrate-protein interactions. Beads featuring hydrazide moieties were adhered to the channel surface, after which carbohydrates (galactose and mannose) were bound to the beads in situ and reacted with fluorescently labelled proteins. Results showed a six-fold increase in fluorescent signal compared to the same process performed on a glass surface without the presence of beads, thereby demonstrating the increase in valence afforded by the method. In a subsequent study, beads, modified with galactose moieties via the in situ functionalisation technique, were used to perform studies of colon tumour cells from a cell sample. Here, the carcinoma cells exhibited superior adhesion than the normal cells due to an increased expression of active galactose receptors, thereby demonstrating the success of the biofunctionalisation method for investigating cellular mechanisms.     

Electron transfer across the interface gold/self-assembled organic monolayer. Comparison of single- and two-component systems

Single- and two-component self-assembled organic monolayers (SAM) formed of HS-C₁₀H₂₀-COOH and the HS-C₁₀H₂₀-COOH + HS-C₆H₁₂-OH mixture and applied on gold electrodes of different shapes and roughness are studied. The resulting monolayers are characterized in 1 M NaNO₃ solutions by the methods of electrochemical impedance spectroscopy in the frequency range from 1 Hz to 100 kHz and cyclic voltammetry in the potential range from 0 to −0.4 V (SCE). Using these method, the behavior of modified single-crystal and polycrystalline gold electrodes in electrolyte solutions of different acidity is assessed and the standard rate constants for the Ru[(NH₃)₆]^3+/2+ redox reaction are determined. The SAM film formed from the ethanol solution of the HS-C₁₀H₂₀-COOH + HS-C₆H₁₂-OH mixture (0.025 M) on the Au(210) singlecrystal face lowers down the rate of the heterogeneous Ru[(NH₃)₆]^3+/2+ reaction from 1.5 to 4.02 × 10⁻⁴ cm/s in the electrolyte solution with pH from 2. In solutions with higher pH, the rate constant is higher by almost an order of magnitude (2.74 × 10⁻³ cm/s). The distribution of micropores in SAM films is studied within the framework of a model of micro-array electrodes. The results of studies are compared with the literature data on the gold electrode in solutions of inactive electrolytes in the absence and in the presence of SAM films formed by alkylmercaptans with equal chain lengths.     

Mapping the nanoparticle-coating monolayer with NMR pseudocontact shifts

Lanthanide ions Yb(3+) and Tb(3+), once bound to the monolayer of organic molecules coating the surface of gold nanoparticles, induce pseudo-contact shifts on the signals of nearby nuclear spins. This not only allows the investigation of the average structure of the ligands in the monolayer but also the mapping of the position of organic molecules bound to it.     

On the asymptotic behavior of a linear viscoelastic fluid

We study the asymptotic behavior of an incompressible viscoelastic fluid and prove that the temporal decay of the energy is similar to one of the memory kernel. The innovative aspect of this research lies in considering the evolutive problem with non‐zero external sources and/or initial histories. Copyright © 2012 John Wiley & Sons, Ltd.     

Schur Functions and Their Realizations in the Slice Hyperholomorphic Setting

In this paper we start the study of Schur analysis in the quaternionic setting using the theory of slice hyperholomorphic functions. The novelty of our approach is that slice hyperholomorphic functions allow to write realizations in terms of a suitable resolvent, the so called S-resolvent operator and to extend several results that hold in the complex case to the quaternionic case. We discuss reproducing kernels and positive definite functions in this setting and we show how they can be obtained using the extension operator and the slice hyperholomorphic product. We define Schur multipliers, and find their co-isometric realization in terms of the associated de Branges–Rovnyak space.     

Tuning Coordination in s‐Block Carbazol‐9‐yl Complexes

1,3,6,8‐Tetra‐tert‐butylcarbazol‐9‐yl and 1,8‐diaryl‐3,6‐di(tert‐butyl)carbazol‐9‐yl ligands have been utilized in the synthesis of potassium and magnesium complexes. The potassium complexes (1,3,6,8‐tBu₄carb)K(THF)₄ ( 1 ; carb=C₁₂H₄N), [(1,8‐Xyl₂‐3,6‐tBu₂carb)K(THF)]₂ ( 2 ; Xyl=3,5‐Me₂C₆H₃) and (1,8‐Mes₂‐3,6‐tBu₂carb)K(THF)₂ ( 3 ; Mes=2,4,6‐Me₃C₆H₂) were reacted with MgI₂ to give the Hauser bases 1,3,6,8‐tBu₄carbMgI(THF)₂ ( 4 ) and 1,8‐Ar₂‐3,6‐tBu₂carbMgI(THF) (Ar=Xyl 5 , Ar=Mes 6 ). Structural investigations of the potassium and magnesium derivatives highlight significant differences in the coordination motifs, which depend on the nature of the 1‐ and 8‐substituents: 1,8‐di(tert‐butyl)‐substituted ligands gave π‐type compounds ( 1 and 4 ), in which the carbazolyl ligand acts as a multi‐hapto donor, with the metal cations positioned below the coordination plane in a half‐sandwich conformation, whereas the use of 1,8‐diaryl substituted ligands gave σ‐type complexes ( 2 and 6 ). Space‐filling diagrams and percent buried volume calculations indicated that aryl‐substituted carbazolyl ligands offer a steric cleft better suited to stabilization of low‐coordinate magnesium complexes.