Mineral composition of fruit by-products evaluated by neutron activation analysis

Brazil is one of the largest producers of fruits cropping 40 million tons per year. In agro-food processing, approximately 50 % of raw material is discarded generating large amounts of by-products. The lack of information on the nutritional quality of agroindustrial by-products precludes their potential use in the manufacture of food products accessible to all. In this context, the objective of this work was to investigate the nutritional quality of by-products of the industrial processing of fruits. Samples of bagasse, peel and seeds of several fruits (banana, camu camu, coconut, cupuaçu, guava, jackfruit, mango, orange, papaya, pineapple, and soursop) were analysed by neutron activation analysis for the determination of Br, Ca, Co, Cr, Cs, Fe, K, La, Na, Rb, Sc and Zn. In general, higher levels of minerals were found in the by-products rather than in the pulps of fruits. This indicates that the use of the by-products should be encouraged, thereby reducing the economic and environmental impact of waste generated by agroindustrial processing.     

Evaluation of differential protein expression in Haliclona aquarius and sponge-associated microorganisms under cadmium stress

A comparative proteomic approach was used to assess differentially expressed proteins in marine sponges after 36 h of exposure to cadmium (Cd). After separation performed by 2-D polyacrylamide gel electrophoresis, 46 protein spots indicated differential expression, and 17 of these proteins were identified by electrospray ionization quadrupole time-of-flight mass spectrometry. From the proteins identified, 76 % were attributed to sponge-associated microorganisms (fungi and bacteria), and 24 % were attributed to Haliclona aquarius. Some of the proteins that were identified may be related to cell proliferation and differentiation or processes of oxidative stress repair and energy procurement. An integrated evaluation based on spot expression levels and the postulated functions of these proteins allowed a more accurate evaluation of the stress caused to the sponge holobiont system by cadmium exposure. This study could provide new insights into the use of a proteomic approach in the marine sponge to assess the effects of Cd pollution in a marine environment.     

Formalism and applications of electrofission and photofission fragment angular distributions

A formalism for the joint analysis of angular distributions of electro- and photofission fragments is presented, utilizing the vitual-photon spectrum technique in DWBA. This formalism is applied to the study of angular distributions for the electrofission of ²³⁸U, measured near the fission barrier, to obtain information about the low-lying levels (J^π, K) of the transition nucleus. The (2⁺, 0), (1^?, 0), and (1^?, 1) levels, previously detected in photofission experiments, were confirmed. Evidences of a significant contributions of (1⁺, 1), (2⁺, 1)and (2⁺, 2) levels are also presented.     

Correlation between Enterococcus faecalis biofilms development stage and quantitative surface roughness using atomic force microscopy.

Biofilms are assemblages of microorganisms and their associated extracellular products at an interface and typically with an abiotic or biotic surface. The study of the morphology of biofilms is important because they are associated with processes of biofouling, corrosion, catalysis, pollutant transformation, dental caries, drug resistance, and so forth. In the literature, biofilms have been examined by atomic force microscopy (AFM), which has proven to be a potent tool to study different aspects of the biofilm development on solid surfaces. In this work, we used AFM to investigate topographical changes during the development process of Enterococcus faecalis biofilms, which were generated on sterile cellulose nitrate membrane (CNM) filters in brain heart infusion (BHI) broth agar blood plates after 24, 36, 72, 192, and 360 h. AFM height images showed topographical changes due to biofilm development, which were used to characterize several aspects of the bacterial surface, such as the presence of extracellular polymeric substance, and the biofilm development stage. Changes in the development stage of the biofilm were shown to correlate with changes in the surface roughness as quantified through the mean roughness.     

Morphological modifications and surface amorphization in ZnO sonochemically treated nanoparticles

Application of nanoscale materials in photovoltaic and photocatalysis devices and photosensors are dramatically affected by surface morphology of nanoparticles, which plays a fundamental role in the understanding of the physical and chemical properties of nanoscale materials. Zinc oxide nanoparticles with an average size of 20 nm were obtained by the use of a sonochemical technique. X-ray diffraction (XRD) associated to Rietveld refinements and transmission electron microscopy (TEM) were used to study structural and morphological characteristics of the samples. An amorphous shell approximately 10 nm thick was observed in the ultrasonically treated sample, and a large reduction in particle size and changes in the lattice parameters were also observed.     

Perspectives on biological growth and remodeling

The continuum mechanical treatment of biological growth and remodeling has attracted considerable attention over the past fifteen years. Many aspects of these problems are now well-understood, yet there remain areas in need of significant development from the standpoint of experiments, theory, and computation. In this perspective paper we review the state of the field and highlight open questions, challenges, and avenues for further development.     

Bioaccumulation pattern of lanthanides in pteridophytes and magnoliophytes species from Atlantic Forest

The availability of chemical elements for plants is mainly dependent on the nature of the soil and characteristics of each species. The transfer factors of lanthanides from the soil to the tree leaves of the Atlantic Forest, Brazil, were calculated for one fern species (Alsophila sternbergii—Pteridophyta division) and four magnoliophytes species (Bathysa australis, Euterpe edulis, Garcinia gardneriana and Guapira opposita—Magnoliophyta division) obtained in two areas of Serra do Mar State Park and collected in two different seasons. Samples were analyzed by instrumental neutron activation analysis (INAA). The soil-to-plant transfer factor (TF = C_plant:C_soil) in magnoliophytes species was correlated to the mass fraction of lanthanides in the soil, described by a exponential model (TF = a.C_soil^−b). Despite the tree fern Alsophila sternbergii presented a hyperaccumulation of lanthanides, this species did not have a significant relationship between TF and mass fraction in soil. Results indicated that plants of Magnoliophyta division selected the input of lanthanides from the soil, while the same was not observed in Alsophila sternbergii.     

The Influence of Network Properties on the Synchronization of Kuramoto Oscillators Quantified by a Bayesian Regression Analysis

The influence of the network structure on the emergence of collective dynamical behavior is an important topic of research that has not been fully understood yet. In the current work, it is shown how statistical regression analysis can be considered to address this issue. The regression model proposed suggests that the average shortest path length is the network property most influencing the degree of synchronization of Kuramoto oscillators. Moreover, this model revealed to be very accurate, being the predicted and measured values of synchronization highly correlated. Therefore, the regression modeling allows predicting the values of the dynamic variable in terms of network structure.     

Cloud Point Extraction as a Procedure of Separation and Pre‐Concentration for Metal Determination Using Spectroanalytical Techniques: A Review

Abstract

Cloud point extraction is a separation and preconcentration procedure that has been extensively applied for trace metal determination in several different matrices. Its major advantages are simple experimental procedures, low cost, high preconcentration factors, and environmental safety. These aspects include it in a set of analytical methods in agreement with the “green chemistry” principles. The surfactants characteristics and the process of micelle formation are outlined for a better understanding of the technique. After general considerations about the cloud point extraction basis and its extraction mechanism for metal chelates are considered, selected spectroanalytical techniques and their application for analysis of the micellar phase are discussed. The micellar extraction in metal speciation analysis, the on‐line incorporation of cloud point extraction to flow injection analysis, and coupling with capillary electrophoresis are described.     

Thermospray nebulization for flame furnace atomic absorption spectrometry — Correlations between spray formation and cadmium analytical sensitivity

Some parameters which influence thermospray formation at low flow rate used in thermospray flame furnace atomic absorption spectrometry were systematically evaluated using spray morphology (through high-speed images acquisition) and Cd determination (used as an analytical probe). A correlation was observed between Cd sensitivity and the Sauter mean diameter of droplets of the spray introduced into the furnace. The SMD was calculated according to the empiric equation proposed by Elkotb and some physical properties of the carriers were used. Among the parameters studied, the most important is the total area of the inlets of flame gases (bottom holes of the nickel atomizer tube), since Cd sensitivity was drastically reduced when this area was increased. Another important parameter is the chemical nature of the carrier solution, which affects the pulse rate of the thermospray. The average rates measured for the different carriers were 320 ± 50, 290 ± 50 and 60 ± 20 pulses/s for water, 0.9 mmol L^− 1 Triton^® X-100 and 44% (w/w) acetonitrile, respectively. Cadmium determinations were performed in certified reference materials using different carrier solutions, and accurate determinations were attained with the use of four carrier liquids (water, 1.4 mol L^− 1 nitric acid, 0.6 mol L^− 1 hydrochloric acid, 8% (w/w) ethanol).