Controlled Synthesis of Carbon‐Encapsulated Copper Nanostructures by Using Smectite Clays as Nanotemplates

Rhomboidal and spherical metallic‐copper nanostructures were encapsulated within well‐formed graphitic shells by using a simple chemical method that involved the catalytic decomposition of acetylene over a copper catalyst that was supported on different smectite clays surfaces by ion‐exchange. These metallic‐copper nanostructures could be separated from the inorganic support and remained stable for months. The choice of the clay support influenced both the shape and the size of the synthesized Cu nanostructures. The synthesized materials and the supported catalysts from which they were produced were studied in detail by TEM and SEM, powder X‐ray diffraction, thermal analysis, as well as by Raman and X‐ray photoelectron spectroscopy.     

Synthesis and structure of N-salicylidene-o-aminophenolato gallium(III) complexes

The reactions of Ga(acac)₃ with N-salicylidene-o-aminophenol (saphH₂) and its 5-methyl (5MesaphH₂) and 5-bromo (5BrsaphH₂) derivatives in alcohols afforded the complexes [Ga(acac)(saph)(EtOH)] (1), [Ga(acac)(5Mesaph)(MeOH)] (2) and [Ga(acac)(5Brsaph)(EtOH)] (3), respectively, in good yields. The crystal structures of 1 and 2 have been solved by single-crystal X-ray crystallography. All three complexes are mononuclear with the Ga^III atoms being surrounded by a dianionic tridentate Schiff base ligand, one bidentate acac⁻ ligand and a terminal alcohol molecule. Characteristic IR data are discussed in terms of the nature of bonding and the structures of the three complexes.     

Using ICP-qMS to trace the uptake of nanoscale titanium dioxide by microalgae–potential disadvantages of vegetable reference material

As nanoscale materials have gained in economic importance over recent years, concerns about accumulation in the environment and, consequently, analysis of nanoparticles in biological material have increasingly become the focus of scientific research. A nanomaterial used in a wide range of food, consumer and household products is titanium dioxide (nTiO₂). Monitoring of nTiO₂ via determination of elemental titanium (Ti) can be very challenging because of a variety of possible interferences. This work describes problems during the development of a quantification method for titanium dioxide (TiO₂) using inductively coupled plasma-quadrupole mass spectrometry (ICP-qMS). To evaluate the analytical method, certified vegetable reference material NCS DC 73349 was used. Interestingly, measurements of NCS DC 73349 seemed to result in acceptable recovery values—however, this was without considering interferences or conceivable differences in the natural isotopic abundance of the certified titanium calibration solution and NCS DC 73349. Actually, recoveries were lower than initially assumed. The potential interferences causing augmented recovery could be attributed to the presence of the elements sulfur (S) and phosphorus (P), which were able to form oxide ions and nitrogen-interfering species. The effect of such interfering cluster ions could be prevented by dry ashing as a sample preparation step, to evaporate S and P, before digestion with aqua regia in a high-pressure asher (HPA). Final practicability of the analysis method was proved by monitoring the uptake of nTiO₂ by the microalgae Scenedesmus acutus in an environmental exposure study.

Curcumin as the OO bidentate ligand in "2 + 1" complexes with the [M(CO)3]+ (M = Re, 99mTc) tricarbonyl core for radiodiagnostic applications

The synthesis and characterization of "2 + 1" complexes of the [M(CO)(3)](+) (M = Re, (99m)Tc) core with the β-diketones acetylacetone (complexes 2, 8) and curcumin (complexes 5, 10 and 6, 11) as bidentate OO ligands, and imidazole or isocyanocyclohexane as monodentate ligands is reported. The complexes were synthesized by reacting the [NEt(4)](2)[Re(CO)(3)Br(3)] precursor with the β-diketone to generate the intermediate aqua complex fac-Re(CO)(3)(OO)(H(2)O) that was isolated and characterized, followed by replacement of the labile water by the monodentate ligand. All complexes were characterized by mass spectrometry, NMR and IR spectroscopies, and elemental analysis. In the case of complex 2, bearing imidazole as the monodentate ligand, X-ray analysis was possible. The chemistry was successfully transferred at (99m)Tc tracer level. The curcumin complexes 5 and 6, as well as their intermediate aqua complex 4, that bear potential for radiopharmaceutical applications due to the wide spectrum of pharmacological activity of curcumin, were successfully tested for selective staining of β-amyloid plaques of Alzheimer's disease. The fact that the complexes maintain the affinity of the mother compound curcumin for β-amyloid plaques prompts for further exploration of their chemistry and biological properties as radioimaging probes.     

Coset space dimensional reduction and Wilson flux breaking of ten-dimensional $\mathcal{N}=1$ , E8 gauge theory

We consider a supersymmetric E ₈ gauge theory, defined in ten dimensions and we determine all four-dimensional gauge theories resulting from the generalized dimensional reduction à la Forgacs–Manton over coset spaces, followed by a subsequent application of the Wilson flux spontaneous symmetry-breaking mechanism. Our investigation is constrained only by the requirements that (i) the dimensional reduction leads to the potentially phenomenologically interesting, anomaly-free, four-dimensional E ₆, SO₁₀ and SU₅ GUTs and (ii) the Wilson flux mechanism makes use only of the freely acting discrete symmetries of all possible six-dimensional coset spaces. Supported by the EPEAEK II programme IRAKLEITOS. Partially supported by the NTUA programme for basic research “Karatheodoris” and the European Union’s RTN programme under contract MRTN-CT-2006-035505.     

How wall properties control diffusion in grooved nanochannels: a molecular dynamics study

The effect of a geometrically-rough wall, amplified by its degree of wettability and stiffness on diffusion coefficient in cases of fluid flow in nanochannels is studied by non-equilibrium molecular dynamics. Diffusion coefficient values, either inside the grooves or as average channel values are affected by the rough wall characteristics. A significant anisotropy along the directions parallel and normal to the flow is observed inside the grooves, while a critical value of groove length below which this anisotropy is enhanced exists. Wall wettability is the property that affects diffusion the most and could be a means of controlling its behavior.     

A new scalable synthesis of entecavir

A new synthesis of entecavir from d-glucose in an average total yield of 3.5% was achieved via an intramolecular nitrile oxide cycloaddition (INOC) reaction and a Peterson olefination as key-steps. The present process was designed for industrial application, using widely available raw materials, simple and cheap reagents and avoiding low reaction temperatures, which are very common in the synthetic approaches towards similarly complex structures.     

Analysis of 2-aminoacetophenone in wine using a stable isotope dilution assay and multidimensional gas chromatography-mass spectrometry

The key compound in the wine off-flavor phenomenon "Untypische Alterungsnote" (UTA) is 2-aminoacetophenone (AAP). A new method for its quantitative analysis in wine is described. The analysis is based on solid phase extraction with LiChrolut EN as sorbent material followed by multidimensional gas chromatography coupled to mass spectrometry (MDGC-MS). Matrix effects due to the complex wine aroma composition could be overcome by an alkaline washing step of the extract and the use of selected ion monitoring as detection mode. Quantification is based on a stable isotope dilution assay using deuterated 2-aminoacetophenone as internal standard.     

Automated Data Acquisition Setup for Interfacial Tension and Capacitance Measurements at Hg‐Solution Contacts Under LabVIEW Control

A system capable of making highly accurate and reproducible automatic measurements of both interfacial tension and capacitance at Hg‐solution contacts in student and research laboratories is presented, based on the control of an arrangement comprising a lock‐in amplifier, a potentiostat and a three electrode electrochemical cell by means of LabVIEW software.