Two-dimensional electrochemical turbulence during the electrodissolution of metal disk electrodes: Model calculations

We present numerical studies of the spatio-temporal dynamics of disk electrodes with local limit cycle oscillations. The simulations are done with a realistic 3-D geometry of the electrochemical cell and disk-shaped working electrodes (WE). Spatio-temporal chaos is shown to exist from a critical electrode size onwards. It is analyzed by Karhunen-Loève decomposition and Hilbert transform. The former shows that the chaos becomes more complex with increasing system size, the latter allows features that generate the spatio-temporal complexity to be identified, namely, spatially extended 1-D phase defects and topological defects.     

Differential proteome analysis of colon carcinoma cell line SW480 after reconstitution of the tumour suppressor Smad4

The tumour suppressor gene Smad4 is frequently inactivated in gastrointestinal carcinomas. Smad4 plays a pivotal role in transducing signals of the transforming growth factor-β (TGF-β) superfamily of proteins. Inactivation of Smad4 seems to occur late during tumour progression when tumours acquire invasive and metastatic properties. Identification of proteins directly or indirectly regulated by Smad4 would, therefore, ease the future design of new diagnostic and therapeutic strategies for gastrointestinal carcinoma. We have used human colon carcinoma cell line SW480 stably transfected with Smad4 as an in-vitro model system to identify Smad4-regulated proteins by applying two-dimensional gel electrophoresis (2DE) then MALDI-PMF/PFF-MS. We identified a total of 47 protein species with a Smad4-dependent expression. From the functions of the candidate proteins we obtained new insights into Smad4’s participation in processes, for example apoptosis, differentiation, and proliferation.     

Water trapped in dibenzo-18-crown-6: theoretical and spectroscopic (IR, Raman) studies

Experimental (IR and Raman) and theoretical (Kohn-Sham calculations) methods are used in a combined analysis aimed at refining the available structural data concerning the molecular guests in channels formed by stacked dibenzo-18-crown-6 (DB18C6) crown ether. The calculations are performed for a simplified model comprising isolated DB18C6 unit and its complexes with either H2O or H3O+ guests, which are the simplest model ingredients of a one-dimensional diluted acid chain, to get structural and energetic data concerning the formation of the complex and to assign the characteristic spectroscopic bands. The oxygen centers in the previously reported crystallographic structure are assigned to either H2O or protonated species.     

Pyrolysis study of poplar biomass by tunable synchrotron vacuum ultraviolet photoionization mass spectrometry

Pyrolysis is one of the most important methods to convert biomass into biofuel, which is a potential substitute for fossil fuel. The pyrolysis process of poplar biomass, a potential biofuel feedstock, has been studied with tunable synchrotron vacuum ultraviolet (SVUV) photoionization mass spectrometry (PIMS). The mass spectra at different photon energies, temperatures, and time-evolved profiles of selected species during poplar pyrolysis process were measured. Our results reveal that poplar is typical of hardwood according to its relative contents of three lignin monomeric precursors. As temperature increases from 300 to 700 °C, the overall intensities of pyrolysis products decrease due to the gas-phase cracking. Observed intensities of syringyl and guaiacyl subunits of lignin in poplar at low temperature present different trends: the intensities of syringyl subunits of lignin undergo an increase firstly and then a decrease, whereas those of guaiacyl subunits of lignin show decrease continuously. Time-dependent data demonstrate that hemicellulose pyrolysis is faster than lignin in poplar. This work reports a new application of SVUV PIMS in biomass pyrolysis, which performs very well in products analysis.     

Possibilities and Limitations of Different Separation Techniques for the Analysis of the Protein Corona

One of the biggest challenges in the field of nanomedicine is the adsorption of biomolecules on the nanomaterial upon contact with a biological medium. The interactions of the resulting protein corona are essential for their behavior in a biological system. Thus, it is now commonly accepted that understanding the formation and consequently understanding the influence of the protein corona on the biological response is crucial. However, the outcome of the protein corona characterization cannot easily be compared between different studies and techniques, since many different sample preparation procedures exist that are suitable for different materials or methods. Depending on the applied procedure, the nanomaterial–protein system will be altered in a certain way, so that it is necessary to consider the individual influence on the protein corona. Accordingly, the aim of this Minireview is to give an overview of the applied sample preparation methods for the analysis of the protein corona and to evaluate their influence on the outcome of the results especially with regard to the introduced terms “soft” and “hard protein corona”. Special focus will be placed on the comparison of the most commonly used techniques such as centrifugation, magnetic, and chromatographic separation.     

Luminescence Spectroscopy of Rhodamine Homodimer Dications in Vacuo Reveals Strong Dye-Dye Interactions

Being alone or together makes a difference for the photophysics of dyes but for ionic dyes it is difficult to quantify the interactions due to solvent screening and nearby counter ions. Gas-phase luminescence experiments are desirable and now possible based on recent developments in mass spectrometry. Here we present results on tailor-made rhodamine homodimers where two dye cations are separated by methylene linkers, (CH₂)_n. In solution the fluorescence is almost identical to that from the monomer whereas the emission from bare cation dimers redshifts with decreasing n. In the absence of screening, the electric field from the charge on one dye is strong enough to polarize the other dye, both in the ground state and in the excited state. An electrostatic model based on symmetric dye responses (equal induced-dipole moments in ground state) captures the underlying physics and demonstrates interaction even at large distances. Our results have possible implications for gas-phase Förster Resonance Energy Transfer.     

Nanorattles or Yolk–Shell Nanoparticles—What Are They,How Are They Made,and What Are They Good For?

The development of nanotechnology has led to the design of cutting‐edge nanomaterials with increasing levels of complexity. Although “traditional” solid, uniform nanoparticles are still the most frequently reported structures, new generations of nanoparticles have been constantly emerging over the last several decades. The outcome of this nano‐art extends beyond nanomaterials with alternative compositions and/or morphologies. The current state‐of‐the‐art allows for the design of nanostructures composed of different building blocks that exhibit diverse properties. Furthermore, those properties can be a reflection of either individual features, which are characteristic of a particular building block alone, and/or synergistic effects resulting from interactions between building blocks. Therefore, the unique structures as well as the outstanding properties of nanorattles have attracted increasing attention for possible biomedical and industrial applications. Although these nanoparticles resemble core–shell particles, they have a distinctive feature, which is a presence of a void that provides a homogenous environment for the encapsulated core. In this Review, we give a comprehensive insight into the fabrication of nanorattles. A special emphasis is put on the choice of building blocks as well as the choice of preparation method, because those two aspects further influence properties and thus possible future applications, which will also be discussed.