Surface behavior of nickel powders in aqueous suspensions

The colloidal behavior of nickel aqueous suspensions is studied and compared to that of NiO suspensions. Under acidic conditions, nickel readily dissolves, but no dissolution takes place at basic pH. Zeta potential is studied as a function of pH, showing that the isoelectric point (IEP) occurs at pH 3.5-4. Above the IEP there is a zeta potential plateau, which is associated to the predominance of NiO(OH) species. At pH 9 a new decrease in zeta potential is associated to NiO predominance. XPS studies support that suspensions prepared at pH >9 lead to NiO-enriched species, while suspensions prepared at lower pH form NiO(OH) species.     

Magnetic nanoparticles for local drug delivery using magnetic implants

Magnetic nanoparticles are good candidates used for the targeted delivery of anti-tumor agents. They can be concentrated on a desired region, reducing collateral effects and improving the efficiency of the chemotherapy. We propose a method in which permanent magnets are implanted by laparoscopic technique directly in the affected organ. This method proposes the use of Fe@C nanoparticles, which are loaded with doxorubicin and injected intravenously. The particles, once attracted to the magnet, release the drug at the tumor region. This method seems to be more promising and effective than that based on the application of external magnetic fields.     

Straight to the bar: Molecular nanostructures,graphene, nanotubes. XXIst International Winterschool on Electronic Properties of Novel Materials (IWEPNM 2007), Kirchberg,Austria, 10–17 March 2007

Conference Reports are meant to offer an authoritative view on a recently held scientific meeting rather than a comprehensive list of the conference presentations. Authors are invited to describe what they feel were the most interesting contributions. The Kirchberg Winterschool provided a platform for reviewing and discussing new developments in the field of electronic properties of molecular nanostructures and their applications such as carbon nanotubes, graphene and single molecules. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Highly structured duets in the song of the South American Hornero

The South American Hornero (Furnarius rufus) is a suboscine bird widely known for its mud-made, oven-looking nest. Beyond their architectural skills, the male and female Horneros sing in highly structured duets. The analysis of field recordings reported in this work reveals that as the male increases the note production rate the female responds by switching to different locking states: the ones predicted by the theory of nonlinear forced oscillators. This gives the duet a most appealing rhythm, and unveils the nonlinear nature of the underlying brain activity needed to generate the song.     

Multiparticle production in proton-nucleus collisions at 360 GeV/c using the European Hybrid spectrometer

360 GeV/c proton interactions with aluminium (Al) and gold (Au) targets are studied using the European Hybrid Spectrometer (EHS) equipped with the Rapid Cycling Bubble Chamber (RCBC). Multiplicities, rapidity distributions and correlations between leading and other produced particles are presented and compared with Monte Carlo calculations based on the multi-chain and Lund models.     

An experimental study of the diagnostic potential of laser selective excitation spectroscopy for a potassium plasma

A thermally tunedQ-switched ruby laser of moderate power, with emission wavelength at 6939 Å, has been used to selectively excite the4^{2}P_{3/2}-6^{2}S_{1/2}transition in the atoms of a pure potassium plasma of low degree of ionization produced in a hot cathode diode. A pulse of intensified spontaneous emission has been observed at 6939 Å, 6911 Å, and at a number of other wavelengths. The possibility of using this type of interaction for localized plasma diagnostics has been studied experimentally. It has been found that the intensified signal decay time decreases with increasing electron density, thereby providing a potential means for measurement of this parameter. In particular, it is shown that because of a saturation effect, the recorded signal characteristics depend to some extent on the laser parameters. A specially tailored laser performance is suggested as essential in order to overcome these problems and obtain signals which depend unambiguously on the plasma conditions.     

Topological cross sections and charged particle multiplicities inpp interactions at 360 GeV/c

Using data obtained with EHS equipped with the Rapid Cycling Bubble Chamber (RCBC) exposed to a proton beam of 360 GeV/c, we calculate topological cross sections. We present in great detail the procedure and the techniques used to correct raw data. Finally, we give multiplicity moments and multiplicity correlations and we compare the values obtained in our experiment, together with data at other energies, with different models.     

ANALYSIS OF A LIMPET FISHERY USING A METAPHYSIOLOGICAL STAND-GROWTH MODEL

We use a metaphysiological approach, recently proposed by one of us (WMG), for modeling trophic interactions to develop a model of limpet-algae-kelp dynamics using data obtained by the others (RHB and GMB) from studies along the west coast of South Africa. We test whether the model is able to predict limpet population growth reasonably well in both the presence and absence of kelp and over a range of limpet and algal population densities. We then discuss the development of a limpet fishery, suing the model to predict limpet stand growth under various harvesting regimes. We compare our results to those obtained by others using a classical size-structured approach, and we suggest how both approaches can be combined to obtain a more reliable and applicable model than either on its own.     

The cation-π cloud interaction and the zeolite basicity concept

Two adsorption complexes between pyrrole and alkaline T₆ zeolite clusters were studied theoretically using DFT method. Results show that at B3LYP/6-311+G**//B3LYP/6-31G* the oxygen atoms in LiT₆ are, in average, more charged than in CsT₆. The cation-π complex is more stable than the complex possessing a hydrogen bond between T₆ clusters and pyrrole. Correlations between alkaline cation hardness and ΔH_adsorption (kcal/mol) showed a linear correlation for both complexes, indicating that the driving force for pyrrole adsorption is cation hardness.