Mobilization and speciation of chromium in compost: a methodological approach

An integral approach to study the mobility of chromium in compost is presented. The approach is based on batch pH dependence leaching tests and the analysis of the leachates for total chromium, chromium(VI) and complexes of chromium(III) with natural organic matter. As leachings are performed with no aggressive reagents (ultrapure water with added nitric acid or potassium hydroxide), the method can be considered a good approach to simulate natural scenarios. The analysis of leachates is complemented with the determination of total chromium and total Cr(VI) in the solid sample. Speciation analysis are done by high performance liquid chromatography with inductively coupled plasma mass spectrometry as detection technique; Cr(VI) is determined by ion chromatography, whereas Cr(III) complexes with natural organic matter by size exclusion chromatography. In the compost studied, Cr(VI) accounted for 6% of the total chromium in the solid, whereas no significant amounts of Cr(VI) were mobilized in the pH range studied (4-10). Chromium is mobilized as Cr(III) bound to organic matter, both to humic and fulvic acids, with an increasing contribution of humic acids at higher pHs.     

Effects of simulated deposition of acid mist and iron ore particulate matter on photosynthesis and the generation of oxidative stress in Schinus terebinthifolius Radii and Sophora tomentosa L

Particulate matter is a natural occurrence in the environment, but some industries, such as the iron ore sector, can raise the total amount of particles in the atmosphere. This industry is primarily a source of iron and sulfur dioxide particulates. The effects of the pollutants from the iron ore industries on representatives of restinga vegetation in a Brazilian coastal ecosystem were investigated using physiological and biochemical measures. Two species, Schinus terebinthifolius and Sophora tomentosa, were exposed to simulated deposition of acid mist and iron ore particulate matter in acrylic chambers in a greenhouse. Parameters such as gas exchange, fluorescence emission, chlorophyll content, total iron content, antioxidant enzyme activity and malondialdehyde content were assessed in order to evaluate the responses of the two species. Neither treatment was capable of inducing oxidative stress in S. terebinthifolius. Nevertheless, the deposition of iron ore particulates on this species increased chlorophyll content, the maximum quantum efficiency of photosystem II and the electron transport rate, while iron content was unaltered. On the other hand, S. tomentosa showed a greater sensitivity to the treatments. Plants of S. tomentosa that were exposed to acid mist had a decrease in photosynthesis, while the deposition of iron particulate matter led to an increase in iron content and membrane permeability of the leaves. The activities of antioxidant enzymes, such as catalases and superoxide dismutase, were enhanced by both treatments. The results suggested that the two restinga species use different strategies to overcome the stressful conditions created by the deposition of particulate matter, either solid or wet. It seems that while S. terebinthifolius avoided stress, S. tomentosa used antioxidant enzyme systems to partially neutralize oxidative stress. The findings also point to the potential use of S. tomentosa as a biomarker species under field conditions.     

Evaluation of equivalent linear methods for estimating target displacements of existing structures

This paper presents a statistical study that evaluates the accuracy of four equivalent linear methods which allow the maximum deformation demands of nonlinear structures to be estimated from the maximum deformation demands of the equivalent linear ones. Three of them are defined by displacement ductility ratios, and the other is defined by lateral strength ratios. It is shown from the study that conclusions for the approximate displacements derived from structures with known displacement ductility ratios (new structures) such as the work done by Miranda and Ruiz-Garcia in 2002 [16] are not applicable to structures with known strength ratios (existing structures). The equivalent damping of the equivalent linear systems is usually greater than 5% and the design response spectra specified in codes have a viscous damping ratio of 5% only. Therefore, the highly damped maximum displacement responses of the equivalent linear systems in this study are derived from both damping reduction factors and linear response-history analyses to discuss the effect of different damping reduction factors. Elastoplastic single-degree-of-freedom systems with periods between 0.1 and 3.0 s are considered when subjected to 72 earthquake ground motions recorded on firm sites in California. Mean ratios and the dispersion of approximate to exact maximum inelastic displacements for each method are computed as functions of periods of vibration and strength ratios. This study focuses on existing structures, which already have known vibrating periods and strength ratios.     

Occurrence of copper resistant mutants in the toxic cyanobacteria Microcystis aeruginosa: characterisation and future implications in the use of copper sulphate as algaecide

Freshwater toxic cyanobacteria are an increasing problem to human and animal health. Control of cyanobacteria in water supply reservoirs involves the use of algaecides, such as copper sulphate, usually in a repetitive way. Repercussions of recurrent algaecide treatments on cyanobacteria population dynamics remain still unknown. We studied the adaptation of cyanobacteria to lethal doses of copper sulphate by using Microcystis aeruginosa as an experimental model. A fluctuation analysis demonstrated that copper-resistant cells arise by spontaneous mutations that occur randomly prior to exposition to copper sulphate. The rate of spontaneous mutation from copper sensitivity to resistance was 1.76×10⁻⁶ mutants per cell division. Resistant mutants exhibited a diminished fitness in the absence of copper sulphate, but only these variants were able to grow at Cu²⁺ concentrations higher than 5.8 μM. In addition, copper-resistant cells were significantly smaller than wild-type ones. Warnings on the long-term consequences of repetitive algaecide treatments in water supplies are suggested.     

Application of the Nernst-Planck approach to lead ion exchange in Ca-loaded Pelvetia canaliculata

Ca-loaded Pelvetia canaliculata biomass was used to remove Pb²⁺ in aqueous solution from batch and continuous systems. The physicochemical characterization of algae Pelvetia particles by potentiometric titration and FTIR analysis has shown a gel structure with two major binding groups - carboxylic (2.8 mmol g⁻¹) and hydroxyl (0.8 mmol g⁻¹), with an affinity constant distribution for hydrogen ions well described by a Quasi-Gaussian distribution. Equilibrium adsorption (pH 3 and 5) and desorption (eluents: HNO₃ and CaCl₂) experiments were performed, showing that the biosorption mechanism was attributed to ion exchange among calcium, lead and hydrogen ions with stoichiometry 1:1 (Ca:Pb) and 1:2 (Ca:H and Pb:H). The uptake capacity of lead ions decreased with pH, suggesting that there is a competition between H⁺ and Pb²⁺ for the same binding sites. A mass action law for the ternary mixture was able to predict the equilibrium data, with the selectivity constants α_Ca^H = 9 ± 1 and α_Ca^Pb = 44 ± 5, revealing a higher affinity of the biomass towards lead ions. Adsorption (initial solution pH 4.5 and 2.5) and desorption (0.3 M HNO₃) kinetics were performed in batch and continuous systems. A mass transfer model using the Nernst-Planck approximation for the ionic flux of each counter-ion was used for the prediction of the ions profiles in batch systems and packed bed columns. The intraparticle effective diffusion constants were determined as 3.73 × 10⁻⁷ cm² s⁻¹ for H⁺, 7.56 × 10⁻⁸ cm² s⁻¹ for Pb²⁺ and 6.37 × 10⁻⁸ cm² s⁻¹ for Ca²⁺.     

Influence of added concrete compressive strength on adhesion to an existing concrete substrate

An experimental study was performed to evaluate the bond strength between two concrete layers of different ages, considering different mixtures of added concrete, with different strengths. The specimens first had the roughness of the substrate surface increased by sand blasting. Later, the new concrete was added. Afterwards, slant shear tests were performed to quantify the bond strength in shear. These tests indicated that increasing the compressive strength of the added concrete relative to the compressive strength of the substrate concrete improves the bond strength and changes the rupture mode from adhesive to monolithic. A finite element analysis showed that, increasing the difference between the compressive strengths of the added concrete and the substrate concrete, higher values of normal stress are present in the interface, for the same level of shear stress. The study presented in this paper reveals that the added concrete, normally with higher compressive strength than the substrate concrete, may possibly have an influence on concrete-to-concrete bond strength. Therefore, design of shear at the interface between concrete cast at different ages, according to Eurocode 2, could be improved, since here only the lowest strength concrete is considered.     

Characterization of the Fouled Ballast Layer in the Substructure of a 19th Century Railway Track Under Renewal

The purpose of these field and lab studies undertaken during rehabilitation work being done on an ancient railway line was to characterize a layer of ballast fouled with soil found in the track substructure. The field studies included the characterization of the thickness, grain size distribution and void ratio of the fouled ballast layer, as well as a large number of plate load tests, both on the fouled ballast layer and on the subgrade. The resilient behaviour of the fouled ballast was evaluated in the lab by cyclic triaxial tests on large size reconstituted specimens with distinct fouling indexes (different grain size distribution) and distinct humidity states (dry or wet). The results obtained were used as support for the decision to maintain the fouled ballast layer under the new sub-ballast in a number of stretches of the renewed line.     

On-machine wire electrical discharge dressing (WEDD) of metal-bonded grinding wheels

Traditional multivariate control charts such as Hotelling’s χ ² and T ² control charts are designed to monitor vectors of variable quality characteristics. However, in certain situations, data are expressed in linguistic terms and, under these circumstances, variable or attribute multivariate control charts are not suitable choices for monitoring purposes. Fuzzy multivariate control charts such as fuzzy Hotelling’s T ² could be considered as efficient tools to overcome the problems of linguistic observations. The purpose of this paper is to develop a fuzzy multivariate exponentially weighted moving average (F-MEWMA) control chart. In this paper, multivariate statistical quality control and fuzzy set theory are combined to develop the proposed method. Fuzzy sets and fuzzy logic are powerful mathematical tools for modeling uncertain systems in industry, nature, and humanity. Through a numerical example, the performance of the proposed control chart was compared to the fuzzy Hotelling’s T ² control chart. Results indicate uniformly superior performance of the F-MEWMA control chart over Hotelling’s T ² control chart.     

Platelet‐rich fibrin and collagen membrane in the preservation of the alveolar bone: Feasibility of the elemental inorganic composition and scanning electron microscopy analysis

The success of dental implants is related to the amount, quality, and composition of the alveolar bone. The placement of platelet‐rich fibrin (PRF) clot associated with a resorbable collagen membrane (RCM) in a postextraction alveolus is a technique used for ridge preservation. This case report study analyzed the ultrastructural characteristics of cross‐sectioned alveolar bone that received PRF and RCM using scanning electron microscopy and the inorganic composition using “energy dispersive X‐ray spectrometry,” in order to explore the feasibility of this method to clinical studies. Three alveolar bone samples from two male patients (37 and 58 years old), obtained in the procedure of placing the dental implant, were analyzed. Two bone samples previously received PRF and RCM (M37 and M58), the third sample represented a physiological bone formation without treatment (M37‐control). The bone sample M37 showed irregularly shaped islets of calcified material intermingled with connective tissue. The other samples, from the 58‐year‐old patient with PRF and RCM (M58); and the other untreated bone sample from the same 37‐year‐old patient (M37‐control) showed similar ultrastructural morphology with trabecular conformation without islets agglomerations. The inorganic composition analysis showed higher concentrations of calcium and phosphorus in both samples treated with PRF and RCM in comparison to the untreated bone sample. The Ca/P ratio was higher in the M37 sample compared to the others samples. The results showed morphology and inorganic composition differences among the treatments used, suggesting that this method is feasible to analyze parameters of the alveolar bone tissue.     

Fibroblast growth factor,estrogen, and prolactin receptor features in different grades of prostatic adenocarcinoma in elderly men

The objective was to characterize and associate the receptor reactivities of fibroblastic growth factor (FGF)‐2, FGF‐7, FGF‐8, epidermal growth factor (EGF), α‐actin and vimentin in relation to the androgen receptor (AR), α and β estrogen receptors (ERα and ERβ), and prolactin receptor in the prostate of elderly men showing low‐ and high‐grade adenocarcinoma. Thirty prostatic samples were taken from 60‐ to 90‐year‐old patients without prostatic lesions and with low‐grade cancer and high‐grade cancer, from the University Hospital, School of Medicine, the State University of Campinas. The results showed that increased FGF‐2, FGF‐7, and FGF‐8 receptor reactivities and decreased AR reactivity were verified in both high‐ and low‐grade cancer. However, the FGF‐8 receptor showed greater involvement at the beginning of the malignancy alterations. Increased EGF receptor (EGFR) reactivity and diminished α‐actin immunohistochemistry were identified in both cancer groups. Also, increased ERα, PR, and vimentin receptors were verified in both cancer groups. To conclude, the ERα involvement in the reactive stroma activation led to a microenvironment, which was favorable to cancer progression, due to maximizing stromal imbalance. The prolactin could be related to cancer progression due to its interaction with ERα action, indicating that this hormone could be a relevant target to prevent the estrogenic effects in the prostatic lesions. Both FGF receptor (FGFR)‐2 and FGFR‐8 play a fundamental role in the early stages of prostate cancer, suggesting that these molecules could be a promising therapeutic target. The differential localization of the fibroblastic factors between the prostatic epithelium and stroma of elderly men, who presented prostate cancer, could indicate a favorable distinction for tumoral progression. Microsc. Res. Tech. 76:321–330, 2013. © 2013 Wiley Periodicals, Inc.