Pesticide monitoring programme of the Ministry of Health of Brazil

The structure of the recently introduced Brazilian government programme for monitoring pesticide residues in six major agricultural products is described. Residues found from the analysis of samples of tomatoes and strawberries are discussed in detail. The much greater frequency of detection of pesticide residues, many of which are not approved for use in Brazil, in produce being sold on the domestic market, as opposed to that produced for export, is of major concern. It is perceived that this new monitoring programme will become permanent and be used to underpin enforcement actions that will need to be taken to reduce the numbers of incidents of illegal residues occurring, particularly in fresh fruits and vegetables.     

Effects of contact shape on biological wet adhesion

Wet adhesion is widely adopted in biological adhesion systems in nature. Wet adhesion is studied in this paper with the focus on the effect of different contact shapes (flat, concave, convex, and ring-like) on the adhesion force. The evolution of the liquid bridge between a fiber tip and substrate during the detaching process shows two transition points. The first transition from the radius-controlled to the contact-angle controlled process is critical to influence the strength and robustness of adhesion. We show that a concave shape is more effective than a flat one, while a convex shape has no advantage. A ring-like contact shape has advantages in a hydrophobic environment and on a rough surface.     

Dye-sensitized solar cell based on nanocrystalline TiO<Subscript>2</Subscript> with 3–10 nm in diameter

Nanocrystalline TiO₂ with 3–10 nm in diameter was prepared with a surfactant-template method. Dye-sensitized solar cells were assembled using the prepared nanocrystalline TiO₂ with large surface area and high crystallinity, which achieved significant higher Jsc when compared to cells fabricated with bigger particles of 25 nm in diameter. In the cells with nanocrystalline TiO₂, the sintering temperature drastically affected the conversion performance of the cells.     

Matter Wave Solitons at Finite Temperatures

We consider the dynamics of a dark soliton in an elongated harmonically trapped Bose-Einstein condensate. A central question concerns the behavior at finite temperatures, where dissipation arises due to the presence of a thermal cloud. We study this problem using coupled Gross-Pitaevskii and N-body simulations, which include the mean field coupling between the condensate and thermal cloud. We find that the soliton decays relatively quickly even at very low temperatures, with the decay rate increasing with rising temperature.     

Dielectric behavior of Cu–GeO<Subscript>2</Subscript> cermet thin films

Capacitance and dielectric loss measurements were carried out using an Al/Cu–GeO₂/Al sandwich structure for 0 to 10 vol% Cu films, 120–400 nm thick, deposited at 0.4–1.5 nm/s in the frequency and temperature range 1–10⁶ Hz and 90–573 K, respectively. The variation of capacitance and dielectric loss with frequency and temperature follows the Goswami and Goswami model. Capacitance decreases slowly with increasing thickness and also varies with the change in deposition rate of the cermet film.     

Efficient and stable field emission from the oxidized porous polysilicon using Pt/Ti multilayer electrode

The field emission characteristics of an oxidized porous polysilicon (OPPS) were investigated with a Pt/Ti multilayer electrode, which showed highly efficient and stable electron emission characteristics compared with those of conventional Au/NiCr electrodes. The thin Ti layer played an important role in promoting the adhesion of Pt to SiO₂ surface and the distribution of the electric field on the OPPS surface. Additionally, the Ti layer efficiently blocked the diffusion of emitter metal, which resulted in more reliable emission characteristics.     

Identification of microstructural zones and thermal cycles in a weldment of modified 9Cr-1Mo steel

This paper presents the results of a study on the microstructural and microchemical variations in a multipass Gas Tungsten Arc weld (GTAW) of modified 9Cr-1Mo steel. The changes brought about in the steel due to the heating and cooling cycles during welding and the subsequent effects due to reheating effects during multipass welding are described. Detailed analytical transmission electron microscopy has been carried to study the type and composition of the primary and secondary phases in this steel. The systematic changes in microstructural parameters such as Prior Austenite Grain Size, martensite lath size, number density, size and microchemistry of carbides, have been understood based on the different transformations that the steel undergoes during the heating and cooling process. Based on the observed microstructure, an attempt has been made to identify distinct microstructural zones and possible thermal cycles experienced by different regions of the weldment.     

Effect of copper additions in directly quenched titanium–boron steels

The present study concerns the effect of copper additions on the microstructural evolution and mechanical properties of directly quenched Ti–B steels. Ti and B are added as microalloying elements with an aim of achieving adequate austenite hardenability and Cu is added to retard the austenite (γ) → ferrite (α) transformation. Therefore, the microalloying and Cu additions together allow the transformation of austenite to occur at a lower temperature, resulting in a finer microstructure containing martensitic constituents. The direct-quenching route is adopted with an aim of facilitating the nucleation of the constituent phases from the deformed austenite. In order to circumvent the hot-shortness due to the Cu addition, 0.79 wt% Ni has been added to one of the 1.5 wt% Cu microalloyed steels. The present study has demonstrated that the Ni-containing 1.5Cu–Ti–B steel is capable of providing an attractive combination of strength and ductility comparable to the high strength varieties of HSLA steels in directly quenched condition.     

Effect of preparation technique on the properties of Mo-containing Al-MCM-41

The Al-MCM-41 has been used as support to prepare Mo-containing catalysts. The 12- molybdophosphoric heteropoly acid (HPMo) is used as initial compound. The catalysts are synthesized by two different methods: incipient impregnation with aqueous solution of the acid and mechanochemical synthesis. The samples were tested in the reaction of the thiophene hydrodesulfurization after activation with mixture H₂ + H₂S. The effect of the preparation method of the catalysts on their physicochemical and catalytic properties has been studied. A partial destruction of the loaded compound is observed in mechanochemically treated sample whereas the aggregates are formed from the particles of different size in the impregnated sample. The specific surface area of the sample prepared by mechanical–chemical treatment decreases 2–3 times, while the total pore volume is about four times lower. The HDS activity is higher on the impregnated sample than on the mechanochemically treated one.     

Improved visible-light responsive photocatalytic activity of N and Si co-doped titanias

Thermal reaction of titanium tetraisopropoxide and tetraethyl orthosilicate in 1,4-butanediol afforded nanocrystalline silica-modified titanias having large surface area and superior thermal stability. In this study, the thus-obtained silica-modified titanias were treated in an NH₃ flow at high temperatures, and their physical and photocatalytic properties were investigated. Compared with NH₃-treated TiO₂ without silica modification, the NH₃-treated silica-modified titanias showed a stronger absorption in the visible region (400–500 nm) and had a larger peak at 396 eV in the N 1s XPS spectrum. These results indicate that a larger amount of nitrogen was stably doped in the silica-modified titania. The obtained products exhibited a high photocatalytic activity for degradation of Rhodamine B and decomposition of acetaldehyde under visible light irradiation. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.