Scientific production on tetrachloro-dibenzo-dioxins: A bibliometric study

Summary Tetrachloro-dibenzo-dioxins were declared as human carcinogenic substances in 1997. Objective: to analyse the scientific production about tetrachloro-dibenzo-dioxins between 1976 and 2005. Solla Price and Bradford models were applied. Different aspects of papers were analysed. Impact factor of journals was studied. 3484 articles were found. The number of articles published each year is fitted to Solla Price model. It has been shown the scientific literature dispersion. Specialisation of some journals of Nucleus and 1st Bradford Zone has been shown.     

Antifeedant and toxic effects of sesquiterpenes fromSenecio palmensis to colorado potato beetle

A bioassay-guided fractionation of the aerial parts ofSenecio palmensis resulted in the isolation of two sesquiterpenes, 2,10-bisaboladien-1-one and 11-acetoxy-5-angeloyloxy-silphinen-3-one. The bisabolene and the silphinene represented 0.012% and 0.024% of the plant dry weight, respectively. Both compounds showed antifeedant activity againstLeptinotarsa decemlineata larvae and adults in short-term choice and no-choice bioassays. Both compounds were also tested against different species of phytopathogenic fungi. The beetles were more sensitive to these compounds in choice than in no-choice assays, with a gradient of increasing sensitivity from second instars to adults. Bisabolene was 45 times less active as an antifeedant than juglone, which was tested as a positive control. The silphinen was more active than the bisabolene, with a range of activity similar to juglone. Furthermore, exposure of fourth instars to these compounds over a 24-hr period resulted in reduced feeding and growth rates. To distinguish between antifeedant and toxic effects, growth efficiencies were calculated as the slope of the regression of relative growth rate on relative consumption rate. The comparison of these results with those of antifeedant simulation and contact toxicity bioassays indicates that feeding inhibition is the primary mode of action of the bisabolene, while the silphinene shows both antifeedant and toxic effects.     

Synthesis and characterisation of magnetite nanoparticles using gelatin and starch as capping agents

Nanoparticles of magnetite passivated with gelatin and starch were synthesised using a co‐precipitation technique. The nanoparticles were characterised using ultraviolet–visible (UV–vis), dynamic light scattering (DLS), Zeta potential, transmission electron microscope (TEM), X‐ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The UV–vis spectra showed characteristic surface plasmon resonance of magnetite nanoparticles. The DLS results showed the nanoparticles to have average hydrodynamic diameters of 138 ± 2 and 283 ± 21 nm for particles passivated with gelatin and starch, respectively. The stability in a colloidal solution was greater in nanoparticles passivated with gelatin than nanoparticles obtained with starch, as can be seen by their Zeta potential value (−31 ± 2 and −16 ± 0.5 mV, respectively). According to the TEM evaluation, the use of gelatin allowed to obtain nanoparticles with a spherical morphology and an average size of 10 ± 2 nm. However, when using starch the nanoparticles exhibited diverse morphologies with an average size of 25 ± 7 nm. The XRD results confirmed the crystalline structure of the samples, which showed crystallite sizes of 14.90 and 24.43 nm for nanoparticles passivated with gelatin and starch, respectively. FTIR analysis proved the establishment of interactions between functional groups of biopolymers and magnetite nanoparticles.Inspec keywords: crystallites, nanofabrication, ultraviolet spectra, gelatin, surface plasmon resonance, transmission electron microscopy, scanning electron microscopy, visible spectra, X‐ray diffraction, iron compounds, electrokinetic effects, particle size, colloids, nanoparticles, nanomedicine, precipitation (physical chemistry), light scattering, magnetic particles, Fourier transform infrared spectra, nanomagnetics, filled polymers, nanocompositesOther keywords: magnetite nanoparticles, gelatin, starch, characteristic surface plasmon resonance, capping agents, passivation, co‐precipitation technique, ultraviolet–visible spectra, zeta potential value, dynamic light scattering, DLS, transmission electron microscopy, TEM, X‐ray diffraction, XRD, Fourier transform infrared spectroscopy, FTIR, surface plasmon resonance, hydrodynamic diameters, colloidal solution, spherical morphology, crystalline structure, crystallite size, biopolymers, Fe₂ O₃      

Basic chemically recuperated gas turbines—power plant optimization and thermodynamics second law analysis

One of the proposals to increase the performance of the gas turbines is to improve chemical recuperated cycle. In this cycle, the heat in the turbine exhaust gases is used to heat and modify the chemical characteristics of the fuel. One mixture of natural gas and steam receives heat from the exhaust turbine gases; the mixture components react among themselves producing hot synthesis gas. In this work, an analysis and nonlinear optimization of the cycle were made in order to investigate the temperature and pressure influence on the global cycle performance. The chemical composition in the reformer was assumed according to chemical equilibrium equations, which presents good agreement with data from literature. The mixture of hot gases was treated like ideal gases. The maximum net profit was achieved and a thermodynamic second law analysis was made in order to detect the greatest sources of irreversibility.     

Developing regional calibration coefficients for estimation of hourly global solar radiation in Ireland

This study proposed regional coefficients for estimating hourly global solar radiation through the adaptation of some empirical models that relate radiation to climatological and geographical variables. A total of 10 models were adapted over 7 stations in Ireland. The performance of the models was evaluated using some selected error indicators including the global performance index which combines all other error indices. The results indicated that the sunshine based regional calibration coefficients generated through a polynomial approach was most superior over other models with the lowest RMSE (0.2–0.3?MJm^?2?hr^?1), MAE (0.1–0.2?MJm^?2?hr^?1) and Pbias (0–7.0%) and highest R² and KGE (>0.85). The study found no local effect such as instrumental siting, observational uncertainty and climate on the variations of these coefficients. This outcome will therefore facilitate the design of various local and/or regional solar energy applications at microscale in a temperate region.     

Fabrication and characterization of iron and fluorine co-doped BST thin films for microwave applications

The effects of fluorine co-doping by means of a post-thermal annealing process of iron-doped BST thin films in a fluorine-containing atmosphere have been investigated. XPS and ToF-SIMS sputter depth profiling verified a homogeneous fluorine distribution in the thin films. By employing EPR, it was shown that singly charged ( $ {\text{Fe}}_{\text{Ti}}^{\prime } $ – $ {\text{V}}_{\text{O}}^{ \cdot \cdot } $ )^· defect complexes, as well as ‘isolated’ $ {\text{Fe}}_{\text{Ti}}^{\prime } $ centres with a distribution of $ {\text{F}}_{\text{O}}^{ \cdot } $ sites in remote coordination spheres exist in the fluorinated films. Tunability enhancement due to fluorine co-doping as well as a Q-factor enhancement due to iron doping is demonstrated.     

Thermoeconomic analysis of a Cuban sugar cane mill

Cogeneration is usual practice in sugar-cane mills. In this work, thermoeconomic analysis is applied to the cogeneration system of a typical Cuban sugar-cane mill. Two different cost attribution methods, the extraction method and the equality method are used to evaluate the exergetic and monetary (operational) costs of each flux within the system, especially the steam and generated power. The methodology indicates the equipment responsible for the greatest irreversibility and for the increase in the costs of the products of the system.