Removal Of Glyphosate Herbicide From Water Using Biopolymer Membranes.

Enormous amounts of pesticides are manufactured and used worldwide, some of which reach soils and aquatic systems. Glyphosate is a non-selective herbicide that is effective against all types of weeds and has been used for many years. It can therefore be found as a contaminant in water, and procedures are required for its removal. This work investigates the use of biopolymeric membranes prepared with chitosan (CS), alginate (AG), and a chitosan/alginate combination (CS/AG) for the adsorption of glyphosate present in water samples. The adsorption of glyphosate by the different membranes was investigated using the pseudo-first order and pseudo-second order kinetic models, as well as the Langmuir and Freundlich isotherm models. The membranes were characterized regarding membrane solubility, swelling, mechanical, chemical and morphological properties. The results of kinetics experiments showed that adsorption equilibrium was reached within 4 h and that the CS membrane presented the best adsorption (10.88 mg of glyphosate/g of membrane), followed by the CS/AG bilayer (8.70 mg of glyphosate/g of membrane). The AG membrane did not show any adsorption capacity for this herbicide. The pseudo-second order model provided good fits to the glyphosate adsorption data on CS and CS/AG membranes, with high correlation coefficient values. Glyphosate adsorption by the membranes could be fitted by the Freundlich isotherm model. There was a high affinity between glyphosate and the CS membrane and moderate affinity in the case of the CS/AG membrane. Physico-chemical characterization of the membranes showed low values of solubility in water, indicating that the membranes are stable and not soluble in water. The SEM and AFM analysis showed evidence of the presence of glyphosate on CS membranes and on chitosan face on CS/AG membranes. The results showed that the glyphosate herbicide can be adsorbed by chitosan membranes and the proposed membrane-based methodology was successfully used to treat a water sample contaminated with glyphosate. Biopolymer membranes therefore potentially offer a versatile method to eliminate agricultural chemicals from water supplies.

Efficacy Of Ethylene-diamine-tetra-acetic Acid Associated With Chlorhexidine On Intracanal Medication Removal: A Scanning Electron Microscopy Study.

The aim of this study was to evaluate the effectiveness of 17% ethylene-diamine-tetra-acetic acid (EDTA) used alone or associated with 2% chlorhexidine gel (CHX) on intracanal medications (ICM) removal. Sixty single-rooted human teeth with fully formed apex were selected. The cervical and middle thirds of each canal were prepared with Gates Glidden drills and rotary files. The apical third was shaped with hand files. The specimens were randomly divided into two groups depending on the ICM used after instrumentation: calcium hydroxide Ca(OH)(2) +CHX or Ca(OH)(2) +sterile saline (SS). After seven days, each group was divided into subgroups according to the protocol used for ICM removal: instrumentation and irrigation either with EDTA, CHX+EDTA, or SS (control groups). All specimens were sectioned and processed for observation of the apical thirds by using scanning electron microscopy. Two calibrated evaluators attributed scores to each specimen. The differences between the protocols for ICM removal were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Friedman and Wilcoxon signed rank tests were used for comparison between the score of debris obtained in each root canal third. Remains of Ca(OH)(2) were found in all specimens independently of the protocol and ICM used (P > 0.05). Seventeen percent EDTA showed the best results in removing ICM when used alone (P < 0.05), particularly in those associated with CHX. It was concluded that the chelating agent 17% EDTA significantly improved the removal of ICM when used alone. Furthermore, the type of the vehicle associated with Ca(OH)(2) also plays a role in the ICM removal.

Emergent Antiferromagnetism Out Of The Hidden-order" State In Uru2si2: High Magnetic Field Nuclear Magnetic Resonance To 40 T."

Very high field (29)Si-NMR measurements using a fully (29)Si-enriched URu(2)Si(2) single crystal were carried out in order to microscopically investigate the hidden order (HO) state and adjacent magnetic phases in the high field limit. At the lowest measured temperature of 0.4 K, a clear anomaly reflecting a Fermi surface instability near 22 T inside the HO state is detected by the (29)Si shift, (29)K(c). Moreover, a strong enhancement of (29)K(c) develops near a critical field H(c) ≃ 35.6 T, and the ^{29}Si-NMR signal disappears suddenly at H(c), indicating the total suppression of the HO state. Nevertheless, a weak and shifted (29)Si-NMR signal reappears for fields higher than H(c) at 4.2 K, providing evidence for a magnetic structure within the magnetic phase caused by the Ising-type anisotropy of the uranium ordered moments.

Engineered Nanoparticles And Organic Matter: A Review Of The State-of-the-art.

Growth in the development and production of engineered nanoparticles (ENPs) in recent years has increased the potential for interactions of these nanomaterials with aquatic and terrestrial environments. Carefully designed studies are therefore required in order to understand the fate, transport, stability, and toxicity of nanoparticles. Natural organic matter (NOM), such as the humic substances found in water, sediment, and soil, is one of the substances capable of interacting with ENPs. This review presents the findings of studies of the interaction of ENPs and NOM, and the possible effects on nanoparticle stability and the toxicity of these materials in the environment. In addition, ENPs and NOM are utilized for many different purposes, including the removal of metals and organic compounds from effluents, and the development of new electronic sensors and other devices for the detection of active substances. Discussion is therefore provided of some of the ways in which NOM can be used in the production of nanoparticles. Although there has been an increase in the number of studies in this area, further progress is needed to improve understanding of the dynamic interactions between ENPs and NOM.

Resistência à compressão e remoção de folhas da cana-de-açúcar visando à colheita mecânica

Sugarcane holds an important place in the Brazilian economy. Grate part of the sugarcane harvested still accomplished largely manually. Sugarcane harvesters available in Brazil use the technology to chop the cane into 200 to 300 mm billets to allow on the go cane transferring to transport, contradicting the traditional method of whole stalk sugarcane harvesting system. In order to make whole stalk mechanical harvesting system possible, one of the barriers to be expired is the mechanical removal of the straw. The design of a mechanism that accomplishes this operation depends directly on the knowledge of the mechanical properties of the sugarcane related to its resistance to compression and the forces necessary to remove the leaves from the stalk. Compression tests were conducted using the universal testing machine. For leaves removal test by friction, a special apparatus was designed to allow the registration of the normal and traction force. The sugarcane stalk can resist up to 4.9 MPa. With a normal pressure of 0.8 MPa, which correspond to a friction force of 315 N, it is possible to remove the leaves, independent of its location in the sugarcane stalk.

Prosody, focus, and word order

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Adesão de linhagem selvagem de Streptococcus thermophilus em superfície de aço inoxidável e efeitos da higienização na sua remoção

A wild strain of Streptococcus thermophilus isolated from pasteurized milk was evaluated using an experimental model with respect to its adhesion onto stainless steel surfaces and its behaviour when submitted to cleansing and sanification. In milk, the adhesion of the microorganism on to stainless steel surfaces was studied after 6 hours of contact at 45°C with agitation, and after a cleansing process involving cleaning stages with alkaline and acid detergents followed by sanification, in order to evaluate the resistance of the adhered cells. The microorganism adhered to stainless steel surfaces producing a cell load of 10(4) CFU/cm². After alkaline cleansing, no adhered cells were detected but 6 CFU/cm² were still detected on the surfaces after acid cleansing. Cleansing, followed by sanification with sodium hypochlorite, was sufficient to reduce the load of wild S. thermophilus on the stainless steel surfaces to non-detectable levels. The experimental model proved adequate for the study indicating that the wild microorganism S. thermophilus produces biofilms on stainless steel surfaces. Alkaline cleansing remove more that 99.9% of the adhered cells. The few cells adhered on the surface are removed by acid cleansing demonstrating the need to use different steps and types of detergent for efficient cleansing. The best results for the removal of these biofilms are obtained by using alkaline cleansing followed by acid cleaning, this procedure being more efficient when complemented by sanification with sodium hypochlorite.

Paramentros fisiologicos, motores e morfologicos de bailarinas classicas

Universidade Estadual de Campinas . Faculdade de Educação Física