Organophosphorus compounds constitute an important class of pesticides whose the toxicity of which arises from the inhibition of the acetylcholinesterase enzyme. They exhibit a wide range of ...physico-chemical properties, thus rendering their determination in complex oil samples particularly difficult. To facilitate their analysis at the trace level in various samples (environmental waters, soils, vegetables…), molecularly imprinted polymers (MIPs) that are synthetic polymers possessing specific cavities designed for a target molecule have been prepared. Often called synthetic antibodies, MIPs can replace antibodies in different application fields. Indeed, as immunosorbents, MIPs can be used as selective sorbents for the solid phase extraction of target analytes from complex matrices or as recognition elements in sensors. Their synthesis, characterization and use as selective sorbent for the selective recognition of organophosphorus pesticides have been already largely described and are summarized in this review.
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•Synthesis and characterization of MIPs for organophophorus pesticides.•Potential of MIPs used as extraction sorbents or as sensing element of sensors.•MIPs for the determination of organophophorus pesticides in complex samples.
This work investigates the origin of the simultaneous increase in strength and ductility that takes place in Mg polycrystals alloyed with Al and Zn solutes. With that purpose, twelve polycrystalline ...binary Mg–Zn and Mg–Al alloys, with up to 2 wt % of alloying additions and average grain sizes comprised between 3 and 42 μm, were prepared by casting, hot rolling and annealing and were tested at room temperature and quasi-static strain rates. Electron backscattered diffraction-assisted slip trace analysis was then utilized to characterize slip activity, and the latter was related to the grain size, to the texture, and to the topology of the grain boundary network. Basal slip was found to be the dominant deformation mechanism in all the binary alloys, irrespective of composition and grain size. Alloying additions were observed to have little influence on texture development but acted as strong modifiers of the topology of the grain boundary network developed during processing. In particular, they reduced the connectivity of grains that are well oriented for basal slip, preventing intergranular slip localization and, in turn, leading to considerable strengthening of basal slip. Solutes act also as enhancers of diffuse slip within individual grains. It is proposed that the simultaneous increase in strength and ductility of Mg alloys by the addition of solutes must be understood as a multiscale phenomenon resulting from the coupling of solute-dislocation interactions at the atomic scale with alterations of the topology of the grain boundary network at the mesoscale.
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In this work electron backscattered diffraction (EBSD)-assisted slip trace analysis and transmission electron microscopy have been utilized to investigate the interaction of basal dislocations with ...precipitates in the Mg alloys Mg-1%wt.Mn-0.7%wt.Nd (MN11) and Mg-9%wt.Al-1%wt.Zn (AZ91), with the ultimate aim of determining the origin of their poor precipitation hardening. Precipitates in these alloys have a plate-shaped morphology, with plates being, respectively, perpendicular (MgxNdy) and parallel (Mg17Al12) to the basal plane of the magnesium matrix. Mechanical tests were carried out in solid solution and peak-aged samples, in tension and compression, both at RT and at moderate temperature (250 °C). EBSD-assisted slip trace analysis revealed a clear dominance of basal slip under a wide range of testing conditions in the peak-aged MN11 and AZ91 alloys. At room temperature, the origin of the low precipitation hardening lies at the easiness with which precipitates are sheared by basal dislocations, which is promoted by the excellent lattice matching at the precipitate-matrix interface. At high temperature, dislocation-precipitate interactions are highly dependent on the deformation mode. In tension, enhanced basal slip localization gives rise to high stress concentrations at the intersection between coarse slip traces and particle interfaces, leading to precipitate fracture; in compression, a more homogenous distribution of basal slip leads to the dominance of particle shearing. Our study demonstrates experimentally that basal dislocations are able to shear, and even fracture, the MgxNdy and Mg17Al12 plates when, for appropriate testing conditions, the local stress due to dislocation accumulation at particle interfaces exceeds the precipitate strength.
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Solid phase extraction for sample pretreatment offers many advantages, including short processing time, rapid separation, high enrichment efficiency and recovery rate, no emulsion formation, low ...cost, low solvent consumption as well as the ability to be coupled with different advanced detection techniques. However, the desirable characteristics of the solid phase extraction methods cannot be materialized unless a proper sorbent is used. The remarkable properties of graphene and graphene-based materials, particularly their ultra-large specific surface area and delocalized π-electron system, enhance their potential as efficient sorbents in solid phase extraction. This paper reviews the developments in the applications of graphene and novel graphene-based materials as sorbents in conventional solid-phase extraction, solid-phase microextraction, dispersive solid-phase extraction, pipette tip solid-phase extraction, and magnetic solid-phase extraction in the past 10 years. In addition, existing challenges and possible future developments in the applications of graphene and graphene-based materials as sorbents are discussed.
•Properties of graphene and graphene-based materials are discussed.•Applications in different modes of solid phase extraction are reviewed.•Existing challenges and possible future developments in the applications summarized.
•Magnetic ionic covalent organic frameworks consisting of amino acid ionic liquids were designed for the first time.•The adsorption mechanism conforms to the theoretical screening of ionic ...liquids.•Magnetic ionic covalent organic frameworks as sorbent showed selective adsorption for benzimidazoles.•A method for determination of benzimidazoles in plasma was established based on magnetic ionic covalent organic frameworks.
Advancing the frontier of material design, our innovative magnetic ionic covalent organic framework (MiCOF) masterfully overcomes traditional barriers in selective adsorption, pioneering new functionalities and surface engineering techniques to effectively target and mitigate the impacts of benzimidazoles (BZDs). In previous studies, the idea of designing magnetic nanomaterials through theoretical screening of ionic liquids has been successfully proposed. This work proposed a theoretical and practical design for MiCOFs, aimed at providing a sensitive, selective, rapid, and straightforward method for analyzing trace substances in complex biological matrices. In a gentle one-pot process, the surface of Fe3O4 was coated with covalent organic frameworks (COFs) layer, followed by the modification with amino acid ionic liquid (AAIL) through covalent radical polymerization, facilitated by the abundant unsaturated vinyl groups present. This resulted in MiCOFs (Fe3O4@COF-AAIL) with a stable structure. Compared to unmodified Fe3O4@COF, Fe3O4@COF-AAIL exhibited excellent adsorption selectivity for BZDs. This enhanced selectivity is primarily due to the strong hydrogen bonds and π-π interactions between AAIL and BZDs, aligning well with COSMO-RS theoretical screening predictions. The development of magnetic dispersive solid-phase extraction (MDSPE) enabled rapid processing of BZDs in plasma with low matrix effects (0.9–1.3). This study not only validates a robust framework for the selective separation of trace contaminants in complex biological matrices but also advances the design and application of MiCOFs, setting a new paradigm in material science that could transform the design of novel materials for specific tasks.
•Magnetic nanoparticles (MNPs) overcome limitations in solid-phase extraction (SPE).•MNPs are characterized by ease of surface modification and versatility.•Great interest has been aroused in the use ...of MNPs in SPE.•MNPs allow easy and rapid isolation of analytes using a magnet.•Magnetic SPE isolates analytes from samples with complex matrices effectively.
The need to obtain meaningful results as the basis for determining the content of trace amounts of analytes has become the driving force behind the development of modern analytical techniques, including sample-preparation techniques, such as solid-phase extraction (SPE). Recently, great interest was aroused in the use of magnetic nanoparticles (MNPs) in SPE. These materials exhibit high selectivity, and, in small amounts, can provide high recovery of analytes, even from large-volume samples. MNPs allow easy, rapid isolation of analytes using an external magnetic field. Simplicity in use, ease of surface modification and the versatility of MNPs mean that they are now widely used in many fields, including biotechnology, medicine and analytical chemistry. In magnetic SPE, these materials provide effective isolation and/or enrichment of the analytes, from samples with complex matrices (e.g. biological, environmental and food samples).
Alumina supported on graphene oxide (Al2O3/GO) nanocomposite as new nanosorbent in dispersive micro-solid phase extraction (DMSPE) for As(V) and Cr(III) preconcentration is described. The crucial ...issue of the study is synthesis of novel nanocomposite suitable for sorption of selected species of arsenic and chromium. Al2O3/GO demonstrates selectivity toward arsenates in the presence of arsenites at pH 5 and chromium(III) ions in the presence of chromate anions at pH 6. The Al2O3/GO nanocomposite was characterized by scanning electron microscopy (SEM) transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and the Raman spectroscopy. The maximum adsorption capacity calculated based on the Langmuir adsorption model were 43.9 mg g−1 and 53.9 mg g−1 for As(V) and Cr(III), respectively. The nanocomposite was used as solid sorbent in preconcentration of As(V) and Cr(III)_ions from water samples and their determination using energy dispersive X-ray fluorescence spectrometry (EDXRF). The As(V) and Cr(III) ions can be quantitatively preconcentrated from 25 to 100 mL aqueous samples within 5 min using DMSPE procedure and 1 mg of Al2O3/GO. The nanocomposite was also used for preparation of Al2O3/GO membrane. Then, As(V) and Cr(III)_ions can be retained under flow condition by passing analyzed solution through Al2O3/GO membrane. Under the optimized conditions, As(V) and Cr(III) ions can be determined with very good recovery (92–108%), precision (RSD 2.7–4.0%) and excellent limit of detection (0.02 ng mL−1 As and 0.11 ng mL−1 Cr). The accuracy of the method was studied by analyzing certified reference materials (NIST 1640a) and spiked real water samples.
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•New nanocomposite for arsenic and chromium speciation was investigated.•Nanocomposite is highly selective toward arsenates and trivalent chromium.•Direct analysis of nanocomposite with analytes without elution step was developed.•Environmentally friendly, solvent-free method for ultratrace analysis was proposed.
Exploring the natural diversity of functional genes/proteins from environmental DNA in high throughput remains challenging. In this study, we developed a sequence-based functional metagenomics ...procedure for mining the diversity of copper (Cu) resistance gene copA in global microbiomes, by combining the metagenomic assembly technology, local BLAST, evolutionary trace analysis (ETA), chemical synthesis, and conventional functional genomics. In total, 87 metagenomes were collected from a public database and subjected to copA detection, resulting in 93,899 hits. Manual curation of 1214 hits of high confidence led to the retrieval of 517 unique CopA candidates, which were further subjected to ETA. Eventually, 175 novel copA sequences of high quality were discovered. Phylogenetic analysis showed that almost all these putative CopA proteins were distantly related to known CopA proteins, with 55 sequences from totally unknown species. Ten novel and three known copA genes were chemically synthesized for further functional genomic tests using the Cu-sensitive Escherichia coli (ΔcopA). The growth test and Cu uptake determination showed that five novel clones had positive effects on host Cu resistance and uptake. One recombinant harboring copA-like 15 (copAL15) successfully restored Cu resistance of the host with a substantially enhanced Cu uptake. Two novel copA genes were fused with the gfp gene and expressed in E. coli for microscopic observation. Imaging results showed that they were successfully expressed and their proteins were localized to the membrane. The results here greatly expand the diversity of known CopA proteins, and the sequence-based procedure developed overcomes biases in length, screening methods, and abundance of conventional functional metagenomics.
This work investigates the strain-dependent activation of second-order <c+a> pyramidal slip and other non-basal systems with increasing tensile strain in a Mg-Zn alloy. With that purpose, a ...polycrystalline solid solution Mg-Zn alloy with ∼2 wt.% Zn (∼0.75 at. %) and with an average grain size of ∼36 μm was processed by casting, hot rolling and subsequent annealing. The slip activity with tensile strain was analyzed by electron backscattered diffraction (EBSD)-assisted slip trace analysis. Basal slip was found to be the dominant deformation mechanism at low strains (∼5-10%). However, at higher strains the activity of pyramidal slip increases significantly due to the hardening of basal slip by Zn solutes. Other non-basal deformation mechanisms, such as compression twinning, cross-slip and slip transfer between pyramidal planes, come into play also at higher strains and are shown to be induced by pyramidal slip. Molecular dynamics (MD) simulations have been used, in particular, to demonstrate the influence of pyramidal dislocations on the nucleation of compression twins. The large availability of deformation mechanisms at high strains contributes to improve the RT ductility of the Mg-Zn alloy.
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An analytical methodology based in the combination of Thin Film Microextraction with Laser-induced Breakdown Spectroscopy (TFME-LIBS) was investigated, for the first time, for detection of Cu, Cr, Ni ...and Pb in aqueous solutions. In this methodology, the analytes were extracted in a thin film of adsorbent material deposited on a solid support, which was introduced in the sample to analyse. After extraction, the analytes retained in the adsorbent were analysed by LIBS. In order to obtain adsorbent films useful for the microextraction step, two different experimental procedures for film generation, denoted as Drop Casting Deposition and Mould Deposition, were evaluated. In both cases, graphene oxide was used as adsorbent material. The mould deposition procedure was found to produce more homogeneous graphene oxide layers, leading to more uniform distribution of the adsorbed analytes on the graphene oxide surface. Experimental parameters affecting the TFME procedure, such as the adsorbent amount and extraction time, were studied. Under optimum microextraction conditions, the analytical figures of merit of the proposed TFME-LIBS method were evaluated, leading to limits of detection ranging from 41 μg kg−1 and 52 μg kg−1. Method trueness, evaluated from the analysis of a real sample of bottle water, led to recovery values about 70%, indicating the existence of strong matrix effects probably due to the presence of major cations in the bottle water. After 50% dilution of the sample with deionized water, recoveries values improved to 100%–108%.
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•TFME-LIBS, using graphene oxide as adsorbent, has been evaluated for the first time.•Thin Film microextraction is an easily automated procedure reducing the sample handling.•Several metals in liquid samples has been detected at μg kg−1 level by LIBS.•Metal chelation step has been avoided with the use of graphene oxide.
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