Trace metal analyses in honey samples from selected countries. A potential use in bio-monitoring

Honey is a sweet product made by bees using nectar from flowers. Concentrations of Ca, K, Mg, Fe, Zn, Mn, Cu, Pb and Cd were determined in 13 honey samples from the selected regions around the world. Levels of Ca, Mg, Cu, Fe, Zn and Mn were measured using flame atomic absorption spectrometry (FAAS). Potassium concentration was determined via flame photometry. Concentrations of Cd and Pb were determined using the electrothermal technique (ETAAS). It was estimated that the examined samples of honey from Greece, Turkey, Spain, Poland, Mexico, Argentina and Italy were of good quality in terms of metal concentrations (compliant with the norms referring to food products – WHO, Fifty-third Report of the joint FAO/WHO Expert Committee on Food Additives; Technical Report Series 776, Geneva), although the analysed samples were not free of heavy metals. The concentrations of the elements in the honey samples ranged from 2.38 to 9.31 μg · g^?1 for Zn, from 3.86 to 35.10 μg · g^?1 for Fe, from 0.19 to 21.64 μg · g^?1 for Mn, from 49.53 to 1006.90 μg · g^?1 for Ca, from 388.25 to 4761.50 μg · g^?1 for K and from 0.20 to 1.53 μg · g^?1 for Cu and regarding heavy metals from 0.11 to 2.78 μg · g^?1 for Pb and from 0.02 to 0.44 μg · g^?1 for Cd. According to these results it was found that the concentrations of heavy metals in the honey samples (except for alfalfa honey and eucalyptus honey from Italy) were under the acceptable limits for foods set out by the FAO/WHO. It was confirmed that the application of chemometric tools supports the extraction of significant information from analytical data, even though the availability of samples is not fully sufficient (this problem is often encountered in environmental analyses).     

On the Fokker-Planck description of compressible fluids

It is shown that the dynamics of a compressible, viscous classical fluid can be brought within the scope of the mixed canonical-dissipative formalism proposed previously as a tool of describing randomly driven systems. The Fokker-Planck equation for compressible fluids is derived and the structure of the Langevin force correlation tensor is discussed in view of the so-called potential conditions.     

Engineering the residual stress state and microstructure of stainless steel with mechanical surface treatments

Four mechanical surface treatments have been considered for the application to austenitic stainless steel structures. Shot peening (SP), laser shock peening (LSP), ultrasonic impact treatment (UIT) and water jet cavitation peening (WJCP), also known as cavitation shotless peening (CSP), have been applied to 8 mm thick Type 304 austenitic stainless steel coupons. This study considers the merits of each of these mechanical surface treatments in terms of their effect on the surface roughness, microstructure, level of plastic work and through thickness residual stress distribution. Microstructural studies have revealed the formation of martensite close to the treated surface for each process. Residual stress measurements in the samples show compressive stresses to a significantly greater depth for the LSP, UIT and WJCP samples compared to the more conventional SP treated sample.     

Geometric Fourier Analysis for Computational Vision

Projective Fourier analysis — geometric Fourier analysis of the group SL(2,), the group identified in the conformal camera that provides image perspective transformations—is discussed in the framework of representation theory of semisimple Lie groups. The compact model of projective Fourier analysis is constructed, complementing the noncompact model proposed before. Detailed mathematical formulation of both models is presented. It is demonstrated that the projective Fourier analysis provides the data model for efficient perspectively covariant digital image representation well adapted to the retino-cortical mapping of biological visual system, and therefore, explicitly designed for the foveated sensors of a silicon retina, the use of which in active vision systems is presently limited due to the lack of such a model.