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Researches on diagnosis and treatment of Alzheimer's disease, the most common type of dementia, are still ongoing. Taurine is frequently used in Alzheimer's disease models due to its protective effects. Metal cation dyshomeostasis is an important etiological factor for Alzheimer's disease. Transthyretin protein is thought to act as a transporter for the Aβ protein that accumulates in the brain and is eliminated in the liver and kidneys via the LRP-1 receptor. However, the effect of taurine on this mechanisms is not fully known. 30 male rats, aged 28 ± 4 months, were divided into 5 groups (n = 6) as follows: control group, sham group, Aβ 1–42 group, taurine group and taurine+Aβ 1–42 group. Oral taurine pre-supplementation was given as 1000 mg/kg-body weight/day for 6 weeks to taurine and taurine+Aβ 1–42 groups. Plasma copper, heart transthyretin and Aβ 1–42, brain and kidney LRP-1 levels were found to be decreased in the Aβ 1–42 group. Brain transthyretin was higher in taurine+Aβ 1–42 group and brain Aβ 1–42 was higher in Aβ 1–42 and taurine+Aβ 1–42 groups. Taurine pre-supplementation maintained cardiac transthyretin levels, decreased cardiac Aβ 1–42 levels and increased brain and kidney LRP-1 levels. Taurine may have a potential to be used as a protective agent for aged people at high risk for Alzheimer's disease. [Display omitted] • Metal cation dyshomeostasis is involved in the pathogenesis of AD. • One of the factors that cause AD is inadequate amyloid clearance. • Transthyretin and LRP-1 are thought to be involved in the clearance of amyloid derivatives. • Taurine can exert its neuroprotective effects in AD by different mechanisms, such as increasing LRP-1 levels. [ABSTRACT FROM AUTHOR]

HIGHLIGHTSFe incorporation significantly accelerated the adsorption of CPX on MCM-41.Fe leaching can be ignored when pH was higher than 4.0.pH played an important role in CPX adsorption on Fe-MCM-41.Co-effect of CPX and metal cations on Fe-MCM-41 was investigated.Fe-MCM-41s with various molar ratios of silicon to iron (20, 40, 80, and 160) were prepared to investigate adsorption properties of ciprofloxacin hydrochloride (CPX) in aqueous solutions. Fe-MCM-41s were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption/desorption isotherms, and infrared spectroscopy (FT-IR). Effects of silicon-iron ratio, adsorbent dosage, pH, and temperature were conducted to explore the adsorption mechanism of CPX on Fe-MCM-41. The results showed that the introduction of iron facilitated the absorption quantity for CPX from 20.04 to 83.33 mg g−1 at 120 min of reaction time, which was mainly attributed to surface complexation. The promotion of hydrophobic effect, electrostatic interactions, and π-π electron donor-acceptor interaction also played coordinate roles in the adsorption process. The experimental kinetic data followed both the pseudo-second-order and intra-particle diffusion models, while the adsorption isotherm data fit well to Freundlich model at high temperature. Thermodynamic study showed that the adsorption was spontaneous. Under the effect of electrostatic interaction, pH of the solution strongly affected CPX adsorption. Five representative metal cations (Ca, Cu, Ni, Pb, and Cd) were chosen to study the effects on CPX adsorption and their complexation. The inhibiting effect of metal cations on CPX adsorption was sequenced in the order of Cu > Ni > Pb > Cd > Ca, which followed the same order as the complexation stability constants between CPX and cations. The Fe-MCM-41 adsorbent possessed excellent reusability for 4 cycles use, suggesting a potential applicability of Fe-MCM-41 to remove CPX in water.

Iron (Fe) (hydr)oxides control the mobility and bioavailability of tetracycline (TC) in waters and soils. Adsorption of TC on Fe (hydr)oxides is greatly affected by polyvalent metals; however, impacts of molar metal/TC ratios on TC adsorptive behaviours on Fe (hydr)oxides remain unclear. Results showed that maximum TC adsorption on ferrihydrite and goethite occurred at pH 5–6. Such TC adsorption was generally promoted by the addition of Cu2+, Zn2+ and Al3+. The greatest increase in TC adsorption was found in the system with molar Cu/TC ratio of 3 due to the formation of Fe hydr(oxide)–Cu–TC ternary complexes. Functional groups on TC that were responsible for the complexation with Cu2+shifted from phenolic diketone groups at Cu/TC molar ratio 1 as excess Al3+ led to the competitive adsorption with Al/TC complexes. For the Zn2+ addition, no significant correlation was found between TC adsorption capacity and molar Zn/TC ratios.

Based on 5,5 ′ -(1,3,6,8-tetraoxobenzo[ lmn ][3,8] phenanthrolin-2-7-diyl)bis-1,3- benzenedicarboxylic acid (H 4 BIPA-TC), two novel 2D coordination polymers, formulated as {[Cd(BIPA-TC) 0.5 (1,4-bib)(H 2 O)]·(H 2 O) 3.5 } n ( 1 ) and {[Cd 2 (BIPA-TC)(4,4 ′ -bibp)(H 2 O)]·(H 2 O)} n ( 2 ) have been solvothermally synthesized with the help of two bis(imidazole) linkers, 1,4-bib and 4,4 ′ -bibp(1,4-bib = 1,4-bis(benzimidazo-1-ly)benzene and 4,4 ′ -bibp = 4,4′-bis(imidazolyl)biphenyl). Single-crystal X-ray diffraction analysis shows that complex 1 is a (4,4)-connected bilayer network structure with the point symbol of (4 6 ·4 8 ) 2 (4 2 ·6 4 ), which further expand into an interestingly 2D + 2D → 3D interweaved framework. Complex 2 possesses a (4,6)-connected network with two kinds of {Cd 2 (COO) 2 } SBUs with the point symbol of (3 2 ·4 2 ·5 2 )(3 4 ·4 4 ·5 4 ·6 3 ), which further pack into a 3D supramolecular architecture through hydrogen bonds. Furthermore, the luminescent recognition properties of 1 and 2 for small organic molecules, nitroaromatic compounds, and metal cations have been explored systematically. [ABSTRACT FROM AUTHOR]

Curcumin, a well-documented phytochemical compound used to treat various diseases because of its more tolerability in the human body and has no side effects. The present study describes the metal chelating ability of Curcumin for Mn 2+ , Fe 2+ and Zn 2+ metal ions and their antioxidant properties using density functional theory in both gas and DMSO solvent phases. Results reveal that the carbonyl group at diketo moiety is destabilized due to the metal ion coordination. The interaction energies reveal that CurEN-Zn 2+ are the most stable rather than the CurEN-Mn 2+ and CurEN-Fe 2+ complexes. The AIM analysis confirms that the interaction between the metal ions and Curcumin are to be electrostatic dominant. The HOMO-LUMO orbital analysis shows that the charge transfer interaction is dominant for CurEN-Mn 2+ and CurEN-Fe 2+ complexes. The DMSO solvent interactions decrease the stability of the CurEN-M 2+ cation complexes. The antioxidant mechanism is more reactive for metal complexes than the isolated Curcumin. Since Curcumin possess both metal chelating and antioxidant properties, it can be used in chelation therapy for the cure of Alzheimer’s disease. [ABSTRACT FROM AUTHOR]

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A novel colorimetric cation sensor based on polyethyleneiminehydrochloride (PEI.HCl) as Schiff base was synthesized. The molecular structure of the PEI.HCl-Schiff base was characterized via FT-IR, 1 H NMR, 13 C NMR, LC-MS and UV–vis spectroscopic methods The chromogenic sensing ability of PEI.HCl-Schiff base was investigated with colorimetric and UV–vis spectroscopy. The designed sensor exhibited highly selective recognition for Fe 2+ , Co 2+ , Cu 2+ , Cr 3+ , and Fe 3+ amongst a wide range of metal ions tested in water. In the presence of these cations, the sensor underwent a dramatic colour change from yellow to green, while the presence of other metal cations such as Mn 2+ , Ni 2+ , Zn 2+ , Cd 2+ , Hg 2+ and Pb 2+ produced no effect on the colour. The absorption spectral changes were observed upon the addition of Fe 2+ , Co 2+ , Cu 2+ , Cr 3+ , and Fe 3+ with impressive naked eye detectable colour change from yellow to dark-gray, light-brown, green, light-green and brown, respectively. The most discernable colour change in the PEI.HCl-Schiff base was caused by Fe 2+ , Co 2+ , Cu 2+ , Cr 3+ , and Fe 3+ suggesting the selective detection of these metal cations. Surprisingly, PEI.HCl-Schiff base behaves as highly selective chemical sensor for the oxidation of Fe2 + to Fe 3+ cations. Moreover, the antimicrobial activity of PEI.HCl-Schiff base was tested for its minimum inhibitory concentration (MIC), and the interaction with calf thymus DNA (CT-DNA) was investigated using UV–vis spectroscopy. DNA cleavage study showed that PEI.HCl-Schiff base can successfully cleave DNA without any external agents. [ABSTRACT FROM AUTHOR]

This study comprises the synthesis of new calix [4] arene thioether derivative (3), its corresponding oligomer (5) and copolymers (6), which are a selective extractant for toxic metal cations and anions and liquid-liquid and solid-liquid extractions of these compounds. Structures of these compounds were described by elemental anaysis, FT-IR, ¹H NMR and 13C NMR. To determine the ion transport properties of the synthesized compounds, transition metal picrate and dichromate liquid-liquid extraction studies were carried out. It is seen from the extraction results that the calixstyrene copolymer (6) has a good selectivity for the Pb2+ and Hg2+ cation from the selected metal cations, but it shows poor extraction behavior towards dichromate anion. [ABSTRACT FROM AUTHOR]

Data obtained in recent years that characterize the sorption capacity of natural sorbents with respect to the cations of a number of metals from nonexchangeable solutions and working fluids are generalized. We develop a technique for estimating the slip of pollutants with solutions in which the concentration of toxic cations does not exceed regulatory requirements. A method for calculating the kinetic curves of sorption is considered, which makes it possible to estimate the concentration of the pollutant coming out of the adsorber and the specific dynamic capacity of the sorbent to any current point of time from the beginning of the process. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) modified with ethylene diamine (EDA) and the amino acids (AAs) Cys, His, Lys or Arg were synthesized, and their structures were confirmed by high resolution transmission electron microscopy, Raman spectrometry and X-ray photoelectron spectrometry. It is found that derivatization of the CDs with various AAs systemically modulates their electronic properties, and this results in a tunable selectivity in detection of metal cations via fluorescence quenching. The probes can be performed in aqueous solutions around pH 7. CDs can be excited under 345 nm excitation at room temperature and exhibit fluorescent peak at 450 nm. The decreasing fluorescence intensity is directly proportional to the concentration of metal cations. The limits of detection is 8.8 μg L for Pb(II), 20 μg L for Hg(II), 3.7 μg L for Cu(II), 5.3 μg L for Zn(II), 16 μg L for Fe(III), and 7.2 μg L for Cr(III), respectively. The different fluorescence response of the AA-modified CDs can be converted to logic gates and applied to photoelectronic nanoprobes by using microprocessors. In our perception, this assay has a large potential in terms of high-throughput screening for trace amounts of metal ions. [ABSTRACT FROM AUTHOR]

Two new symmetrical bis-thiourea, 2,2′-[{(terephthaloylbis(azanediyl)bis(carbonothioyl) bis(azanediyl)}dipropanoic acid] (1A) and 3,3′-[{(terephthaloylbis(azanediyl)bis (carbonothioyl)bis(azanediyl)} dipropanoic acid] (1B) were synthesized by the reaction of terephthaloyl chloride with α- and β-alanine in good yields. Their binding properties were investigated with various metal cations using UV-Vis titration experiments. Both isomers exhibited effective binding with Ag, Cu, Hg, Pb, Fe and Fe cations. However, in the presence of other cations, such as Na, Ni, Co, Cd, Zn, Mn, Mg, Ca, Sn, Al, and anions tetrabutylammonium Cl and HPO , no interaction occurred. Both isomers displayed similar trends towards binding with metal cations. [ABSTRACT FROM AUTHOR]

Protein tyrosine phosphatases are not considered to be metalloenzymes. Yet, they are inhibited by zinc cations and metal and non-metal oxyanions that are chemical analogues of phosphate, e.g. vanadate. Metal inhibition is generally not recognized as these enzymes are purified, supplied, and assayed with buffers containing chelating and reducing agents. We screened a series of cations and anions for their capacity to inhibit protein tyrosine phosphatase 1B and discuss the ensuing general issues with inhibition constants reported in the scientific literature. In contrast to zinc, which binds to the phosphocysteine intermediate in the closed conformation of protein tyrosine phosphatase 1B when the catalytic aspartate has moved into the active site, other divalent cations such as cadmium and copper may also bind to the enzyme in the open conformation. Inhibition by both anions and cations, conditions such as pH, the presence of metal ligands such as glutathione, and the existence of multiple conformational states of protein tyrosine phosphatases in the reaction cycle establish a complex pattern of inhibition of these important regulatory enzymes with implications for the physiology, pharmacology and toxicology of metal ions. [ABSTRACT FROM AUTHOR]

The adsorption of ciprofloxacin (CIP) by bamboo charcoal in aqueous solution was explored under varying pH, salinity, metal cations, and phosphate. The adsorption kinetics and adsorption isotherms were depicted well by the pseudo-second-order and Langmuir models, respectively. The maximum adsorption capacity ( [ABSTRACT FROM AUTHOR]

Human serum albumin (HSA) is an abundant multiligand carrier protein, linked to progression of Alzheimer's disease (AD). Blood HSA serves as a depot of amyloid β (A β) peptide. A β peptide-buffering properties of HSA depend on interaction with its ligands. Some of the ligands, namely, linoleic acid (LA), zinc and copper ions are involved into AD progression. To clarify the interplay between LA and metal ion binding to HSA, the dependence of LA binding to HSA on Zn, Cu, Mg and Ca levels and structural consequences of these interactions have been explored. Seven LA molecules are bound per HSA molecule in the absence of the metal ions. Zn binding to HSA causes a loss of one bound LA molecule, while the other metals studied exert an opposite effect (1-2 extra LA molecules are bound). In most cases, the observed effects are not related to the metal-induced changes in HSA quaternary structure. However, the Zn-induced decline in LA capacity of HSA could be due to accumulation of multimeric HSA forms. Opposite to Ca/Mg-binding, Zn or Cu association with HSA induces marked changes in its hydrophobic surface. Overall, the divalent metal ions modulate LA capacity and affinity of HSA to a different extent. LA- and Ca-binding to HSA synergistically support each other. Zn and Cu induce more pronounced changes in hydrophobic surface and quaternary structure of HSA and its LA capacity. A misbalanced metabolism of these ions in AD could modify interactions of HSA with LA, other fatty acids and hydrophobic substances, associated with AD. [ABSTRACT FROM AUTHOR]

There has been limited research investigating how the mechanisms of aggregation of magnetic nanoparticles (MNPs) are affected by inorganic ions. In this study, Na + , Mg 2 + , Ca 2 + , Sr 2 + and Ba 2 + were selected to systematically study the aggregation mechanisms of Fe 3 O 4 MNPs. The results indicated that divalent cations more significantly affected the stabilities of MNPs than Na + at low concentrations (e.g., 0.1 mM) in a decreasing order of Ba 2 + > Sr 2 + > Ca 2 + > Mg 2 + > Na + . Extended DLVO theory did not offer a satisfactory explanation for the above difference due because it ignores specific ion effects. It was also found that the initial adsorption ratios of these metals by Fe 3 O 4 MNPs were linearly proportional to the hydrodynamic diameter (HDD) of Fe 3 O 4 MNPs before aggregation occurred. In addition to the valence states, the hydration forces and ionic radii of the metal cations were proposed to be other factors that significantly affected the interactions of metal cations with Fe 3 O 4 MNPs based on the excellent linear relationships of the HDD of Fe 3 O 4 MNPs and these three factors. Moreover, a bridging function of divalent cations might develop after aggregation occurred based on the increases in their adsorption amounts and intensities for binding oxygen-containing functional groups. In addition, an increase in the positive ζ potential of MNPs was observed with the addition of divalent cations until 10.0 mM at a pH of 5.0, which potentially enhances the resistance of MNPs to aggregation in aquatic systems compared with Na + . Consequentially, the effects of metal cations on the aggregation of MNPs are determined by the hydration forces, valance states, ionic radii and bond types formed on the MNPs. Thus, the specific ion effects of these cations should be considered in predicting the environmental behaviors of specific nanomaterials. [ABSTRACT FROM AUTHOR]

The adsorption and chromatographic properties of microparticulated diamond (1–2 μm and 4–6 μm fractions) from high pressure and high temperature synthesis (HPHT diamond) are investigated, with a focus on their cation-exchange capacity. Several adsorbents were prepared, either by wet oxidation of the surface of HPHT with H 2 O 2 /H 2 SO 4 or HNO 3 /H 2 SO 4 mixtures, or by oxidation in air at 700 °C, or following a four-step reduction using LiAlH 4 and n -butyllithium. The zeta-potential profiles as a function of pH and ion-exchange capacities were measured for the prepared adsorbents as well as isotherms of adsorption. The ion-exchange selectivity of oxidised HPHT diamond was studied towards alkali, alkaline-earth and transition metal cations. [ABSTRACT FROM AUTHOR]

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[Display omitted] • The synthesized colorimetric chemosensor (BTS) can be an excellent alternative for the detection of Pb2+ ions in • BTS can be used as a highly selective sensor for the Pb2+ cation, with no interference from other cations. • Test strip results indicated that BTS could be the detection of Pb2+ ions in real samples. • The advantages of the BTS are simple preparation steps, the use of inexpensive reagents, lower detection limits, and high selectivity for Pb 2+ than the other chemosensors. In this work, a new benzothiazole azo dye sensor (BTS) was synthesized, and its cation binding affinity was studied using the colorimetric method, UV–vis, and 1H NMR spectral data. The results revealed that the sensor BTS exhibits a remarkable tendency for Pb2+ ion to perform spontaneous visual color change from blue (BTS) to pink (BTS + Pb2+), without any color change in the aqueous solutions of other cations such as Hg2+, Cu2+, Al3+, Ni2+, Cd2+, Ag+ , Ba2+, K+, Co2+, Mg2+, Na+, Ca2+, Fe2+, and Fe3+ ions. The observed selectivity could be due to the formation of the complex (BTS + Pb2+), which led to a blue shift from 586 nm (BTS) to 514 nm (BTS + Pb2+) in the UV spectrum. The job's plot provided the stoichiometry ratio of the complex (BTS + Pb2+) to be 1:1. The limit of detection (LOD) of BTS for Pb2+ ion sensing was obtained at 0.67 µM. Additionally, the binding constant for BTS toward Pb 2+ ion was studied using the Benesi-Hildebrand equation. As a result of the BTS test paper strips investigations, it was found that the synthesized sensor BTS could be used as a rapid colorimetric chemosensor for the detection of the Pb2+ ions in the distilled, tap, and sea waters. [ABSTRACT FROM AUTHOR]

The realization that liquid–liquid phase separation (LLPS) underlies the formation of membraneless compartments in cells has motivated efforts to modulate the condensation process of biomolecules. Increasing evidence shows that metals and inorganic molecules abundantly distributed in cells play important roles in the regulation of biomolecular condensation. Herein, we briefly reviewed the background of biomacromolecular phase separation and summarized the recent research progress on the roles of metals and inorganic molecules in regulating protein and nucleic acid phase separation in vitro and in cells. [ABSTRACT FROM AUTHOR]

The poly(2,5-dihydroxy-1,4-benzoquinone-3,6-methylene) (denoted as PDBM) capable of reversible coordination/uncoordination with both mono- and multivalent cations in aqueous electrolytes is desired to develop safe, sustainable, and cost-effective aqueous rechargeable batteries (ARBs). However, the comprehensive mechanism between the electrochemical performance of PDBM and properties of these metal cations is unclear. Herein, we initially demonstrate the universality of PDBM to reversibly coordinate/uncoordinate with various cations (Na + , Mg 2+ , Ca 2+ , Zn 2+ , Al 3+ , etc. ) with high specific capacities (>200 mA h g -1 ), high rate capabilities (∼20 C), and long cycling life (5000 cycles). Additionally, an unprecedented ion-coordination mechanism is presented: the monovalent cations prefer to occupy the in-plane sites with respect to the benzene rings of PDBM during the electrochemical reduced process, while the multivalent cations with the larger charge density tend to occupy the out-of-plane sites, which can use more active sites in the PDBM molecule and deliver the higher specific capacities. Meanwhile, the redox potential of PDBM decreases with the decrease in the binding energy between metal cations and PDBM molecules. The universality of PDBM to numerous cations is beneficial to design high-safety, low-cost, and long-lifespan ARBs for large-scale energy storage systems by modulating the aqueous electrolytes.

Pitch-related deposition has been a significant issue in paper mills that produce wood-containing paper grades. A component analysis showed that a mill deposit sample was a mixture of wood resin, fiber, metal cations, and other inorganics. Based on the differential scanning calorimeter (DSC) method, some critical parameters, including pH, metal cations, and their interactions, on the thermal stability of pitch-related deposits were studied. The valency of metal cations determined the ability of capturing pitch the formation of deposits. Trivalent Al3+ or Fe3+ ions had much stronger effects than divalent Ca2+, Mg2+, or Mn2+. It was also found that a higher pH and trivalent Al3+ or Fe3+ increased the thermal stability of deposits formed in colloidal pitch solutions.

In this work, the N-confused porphyrin 5,10,15,20-tetraphenyl-2-aza-21-carbaporphyrin (NCTPP) was immobilized on neutral or cationic supports based on silica and on Merrifield resin. The new materials were characterized by appropriate techniques (UV-Vis spectroscopy, SEM, and zeta potential analysis). Piezoelectric quartz crystal gold electrodes were coated with the different hybrids and their ability to interact with heavy metals was evaluated. The preliminary results obtained showed that the new materials can be explored for metal cations detection and the modification of the material surface is a key factor in tuning the metal selectivity.

The environmental impact of nanoplastics has gradually attracted widespread attention; however, nanoplastics of polyvinyl chloride, one of the most commonly used plastics, have not yet been studied. In this study, we investigated the transport, long-term release behavior, and particle fracture of polyvinyl chloride nanoplastics (PVC NPs) in saturated quartz sand with different metal cations, ionic concentrations, input concentrations, and sand grain sizes by determining breakthrough, long-term release, and particle size distribution curves. The breakthrough curves and retention profiles were simulated by a mathematical model. The transport of PVC NPs increased with increased input concentration and sand grain size, which could be predicted by the Derjaguin–Landau–Verwey–Overbeek (DLVO) and colloid filtration theories. Increased ionic concentration and metal cation valence could restrain the transport of PVC NPs in saturated quartz sand owing to the decreased energy barrier between PVC NPs and sand grains. The total released amount of PVC NPs in the long-term release tests with different experimental conditions ranged from 3.91 to 21.95%. Increased sand grain size and decreased metal cation valence and ionic concentration resulted in an increased released amount of retained PVC NPs in saturated quartz sand, indicating increased release ability and mobility. The particle fracture results indicated that the PVC NPs were not broken down during long-term release under the experimental conditions of this research. This opens up a completely new and meaningful study of whether nanoplastics are broken down into smaller nanoplastics during their long-term release under various conditions. [Display omitted] • Decreased IC and metal cation valence improve the transport of PVC NPs. • TransPort of PVC NPs can be predicted by DLVO theory and filtration theory. • The mathematical model can simulate the BTCs of PVC NPs. • The release amount decreased with increased IC and metal cation valence. • The PVC NPs are not broken during the long-term release process. [ABSTRACT FROM AUTHOR]

Background The anionic-polyelectrolyte nature of the wall of Gram-positive bacteria has long been suspected to be involved in homeostasis of essential cations and bacterial growth. A better understanding of the coupling between the biophysics and the biology of the wall is essential to understand some key features at play in ion-homeostasis in this living system. Methods We consider the wall as a polyelectrolyte gel and balance the long-range electrostatic repulsion within this structure against the penalty entropy required to condense cations around wall polyelectrolytes. The resulting equations define how cations interact physically with the wall and the characteristic time required for a cation to leave the wall and enter into the bacterium to enable its usage for bacterial metabolism and growth. Results The model was challenged against experimental data regarding growth of Gram-positive bacteria in the presence of varying concentration of divalent ions. The model explains qualitatively and quantitatively how divalent cations interact with the wall as well as how the biophysical properties of the wall impact on bacterial growth (in particular the initiation of bacterial growth). Conclusion The interplay between polymer biophysics and the biology of Gram positive bacteria is defined for the first time as a new set of variables that contribute to the kinetics of bacterial growth. General significance Providing an understanding of how bacteria capture essential metal cations in way that does not follow usual binding laws has implications when considering the control of such organisms and their ability to survive and grow in extreme environments. [ABSTRACT FROM AUTHOR]

Polyethyleneimine (PEI)–modified reduced graphene oxide (rGO) based fluorescent sensor is reported for metal-ion sensing. PEI–rGO nanocomposites are synthesized by a facile and controllable method using hydrazine hydrate as a main reducing agent and PEI that is a reducing agent, surface modifier and polymer host. The formation of PEI–rGO nanocomposites is confirmed with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV–vis spectroscopy, Zeta potential measurements and Dynamic Light Scattering (DLS) analysis. Afterward, the interaction of fluorescein (FL) with PEI–rGO nanocomposites in aqueous dispersion, leading to the formation of FL/PEI–rGO ternary system, are studied at various conditions by using UV–vis absorption, steady-state and time-resolved fluorescence spectroscopies. It is observed that the photophysical properties of FL are dependent on the amount of both FL and PEI–rGO nanocomposites. The sensing ability of FL/PEI–rGO ternary system are examined in the detection of metal ions as a fluorescent sensor. The spectroscopic data reveal that the FL/PEI–rGO ternary system shows high sensitivity and selectivity for Fe 3+ ions in aqueous solution. The detection limit for Fe 3+ are determined to be 1.12 μM. [ABSTRACT FROM AUTHOR]

The devastating effect of corrosion on the structural integrity of metals surfaces has been of great concern for some time. However, the challenge is to develop a benign and cost effective inhibitor that is highly effective. Addition of substances that exert synergistic influence and blending of different metals inhibitors had been employed. This review article delineates the effect of addition of metals cations and blending on the inhibition efficiency of metals corrosion inhibitors. The mechanisms proposed for the synergistic inhibition resulting from either addition of metals cations or blending are also discuss based on reported experimental data. [ABSTRACT FROM AUTHOR]

Triclosan (TCS) is a broad-spectrum antimicrobial agent that is found extensively in natural aquatic environments. Enzyme-catalyzed oxidative coupling reactions (ECOCRs) can be used to remove TCS in aqueous solution, but there is limited information available to indicate how metal cations (MCs) and natural organic matter (NOM) influence the environmental fate of TCS during laccase-mediated ECOCRs. In this study, we demonstrated that the naturally occurring laccase from Pleurotus ostreatus was effective in removing TCS during ECOCRs, and the oligomerization of TCS was identified as the dominant reaction pathway by high-resolution mass spectrometry (HRMS). The growth inhibition studies of green algae ( Chlamydomonas reinhardtii and Scenedesmus obliquus ) proved that laccase-mediated ECOCRs could effectively reduce the toxicity of TCS. The presence of dissolved MCs (Mn 2+ , Al 3+ , Ca 2+ , Cu 2+ , and Fe 2+ ions) influenced the removal and transformation of TCS via different mechanisms. Additionally, the transformation of TCS in systems with NOM derived from humic acid (HA) was hindered, and the apparent pseudo first-order kinetics rate constants ( k ) for TCS decreased as the HA concentration increased, which likely corresponded to the combined effect of both noncovalent (sorption) and covalent binding between TCS and humic molecules. Our results provide a novel insight into the fate and transformation of TCS by laccase-mediated ECOCRs in natural aquatic environments in the presence of MCs and NOM. [ABSTRACT FROM AUTHOR]

Copyright of Inzynieria Mineralna is the property of Polskie Towarzystwo Przerobki Kopalin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, interactions between cations and non-ionic tensides were investigated. Spectrometric measurements on model-systems (cation+counter ion+tenside) were applied. Interactions were explained based on the position and intensity of absorption maxima. Investigated model-systems were also applied in liquid membrane preparation. Nonionic tensides dissolved in nonpolar organic solvents were tested as possible carriers in liquid membranes for metal cation transport. The effect of their application reflects in decreasing the level of cation transport, caused by strong metal-tenside interactions within the membrane. Nonionic tensides: TX-100, TX-45, Brij 35, Brij 58 and Brij 78 were used in experiments. Interactions with metal cations Pb(II) and Cd(II) and competitive ligands: 18-crown-6 and dibenzo-18-crown-6 dissolved in organic solvents (1,2-dichloroethane, dichloromethane and chloroform) were investigated. The results showed that the strongest interactions occurred between cations and tensides with longer chains, i.e. a higher number of electron-donor centers (TX-100 compared to TX-45). Atomic absorption spectrometry was applied for metal cation concentration measurements, after 3 hours of experiment: lower transport efficiency actually proved the efficiency of nonionic tensides as carriers in liquid membranes. [ABSTRACT FROM AUTHOR]

Organic binder is a significant substitution of the bentonite in iron ore pelletizing process, reducing the exploitation of clay resource and improving the quality of pellets. Fulvic acid is one of the important functional groups of modified humic acid (MHA) binder which is invented by the authors and can be used as an excellent composite binder in pelletizing. This work aims to further study the effect of metal cations on FA adsorption onto natural pure oxides and the wet strength of green pellets made with MHA binder via batch adsorption and pelletizing experiment. The adsorption density of FA onto the natural oxides was significantly improved after adding the metal cations. The zeta potential values of the magnetite particles coated by FA became less negative after adding metal cations before the pH value of 9.2 but more negative after 9.2. The XPS analysis and SEM imaging indicated that the metal cations served as a bridge between FA molecules and the surface of magnetite particles, so that the adsorption of FA onto magnetite was promoted. In addition, the viscosity of FA increased after adding the metal cations. Both of these changes were found to be beneficial for the wet strength of MHA binder pellets. [ABSTRACT FROM AUTHOR]

The association of tungsten(VI) and molybdenum(VI) oxyanions with metal cations was investigated under conditions simulating those prevailing in most natural waters. Potentiometric titrations were carried out for the systems containing tungsten(VI) or molybdenum(VI) anions and metal cations. The selection includes the major metal cations and some other ions of high environmental relevance. At neutral and basic pH values, in the presence of the most abundant metal cations, ionic pair species such as [Ca(WO)] or [Ca(MoO)] are formed to high extents. For the acidic pH range, polyoxoanion associations with cations are also found but are only relevant for tungsten(VI) in the conditions of the natural aquatic systems. The present results provide the basis for studying W(VI) and Mo(VI) speciation in natural aquatic systems, on which the environmental fate, bioavailability and toxicity of the elements depend. [ABSTRACT FROM AUTHOR]

Sorption of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) on a range of dealuminated zeolites were investigated to understand the mechanism of their sorption on microporous minerals, while the influence of common metal cations, solution pH, and humic acid was also studied. Sorption of chlorophenols was found to increase with the hydrophobicity of the sorbates and that of the microporous minerals, indicating the important role of hydrophobic interactions, while sorption was also stronger in the micropores of narrower sizes because of greater enhancement of the dispersion interactions. The presence of metal cations could enhance chlorophenol sorption due to the additional electrostatic attraction between metal cations exchanged into the mineral micropores and the chlorophenolates, and this effect was apparent on the mineral sorbent with a high density of surface cations (2.62 sites/nm) in its micropores. Under circum-neutral or acidic conditions, neutral chlorophenol molecules adsorbed into the hydrophobic micropores through displacing the 'loosely bound' water molecules, while their sorption was negligible under moderately alkaline conditions due to electrostatic repulsion between the negatively charged zeolite framework and anionic chlorophenolates. The influence of humic acid on sorption of chlorophenols on dealuminated Y zeolites suggests that its molecules did not block the micropores but created a secondary sorption sites by forming a 'coating layer' on the external surface of the zeolites. These mechanistic insights could help better understand the interactions of ionizable chlorophenols and metal cations in mineral micropores and guide the selection and design of reusable microporous mineral sorbents for sorptive removal of chlorophenols from aqueous stream. [ABSTRACT FROM AUTHOR]

Polynuclear superhalogen anion Li12F13− and its ionic complexes formed by the interaction with selected metal ions (i.e., Li12F13−Na+, Li12F13−K+, Li12F13−Mg2+, and Li12F13−Zn2+) are proposed and investigated on the basis of ab initio calculations. The thermodynamic stability, vertical excess electron detachment energy, and binding energies between ionic components were examined and discussed. The Li12F13− anion has been proved stable against fragmentation and its vertical electronic stability was found to approach 10 eV. Due to its specific equilibrium structure that resembles a molecular basket, the Li12F13− anion was found capable of trapping positively charged metal ions inside to form strongly bound ionic complexes. The large values of binding energies predicted for the Li12F13−Na+, Li12F13−K+, Li12F13−Mg2+, and Li12F13−Zn2+ systems and their specific equilibrium structures indicate that the Li12F13− anion can be useful as a steric shielding system which protect the metal ions from the interaction with the surroundings. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the efficiency of three new polymers obtained by functionalization of a commercial poly (vinyl chloride) (Mw = 48,000) by grafting diethylenetriamine, 2,6-bis-(chloromethyl) pyridine and 1-chloro-2-phenylaminomethyl-6- phenyl aminomethylene-cyclohex-1-ene groups to extract some metal cations from aqueous solutions. The structural properties of the polymers were systematically investigated by different analytical methods; namely elemental analysis, differential scanning calorimetry and infrared spectroscopy (FT-IR). The percentage of extraction was determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). One of the obtained polymers gave an extraction ratio of La3+ = 99.57% which highlights the importance of the substitution of chlorine atoms by amino groups. [ABSTRACT FROM AUTHOR]

Liquid–liquid extraction of metal ions using some 1,2,4-triazole Schiff base derivatives as new extractants was studied. Fe 2+ , Zn 2+ , Cu 2+ , Co 2+ , Cd 2+ and Pb 2+ were extracted from the aqueous phase into the organic phase and the extractability for each metal ion was determined by atomic absorption. Interestingly, a competitive extraction was also investigated and then examined at different pH in order to explore the effect of the different substituent groups on metal extraction. Accordingly, high selectivity towards Fe 2+ (90.1%) and Pb 2+ (94.3%) provided respectively by the presence of electron withdrawing group and electron donor group was attained. In addition, geometry optimizations of the ground and excited-states of the ligands in order to get better insight into the geometry and the electronic structure were carried out by means of DFT and TD-DFT calculations. [ABSTRACT FROM AUTHOR]

Liquid-liquid extraction of metal ions using pyrane derivatives was studied. Fe2+, Zn2+, Cu2+, Co2+, Cd2+, Ni2+, and Pb2+were extracted from the aqueous phase into the organic phase and the extractability for each metal was determined by atomic absorption. Interestingly, a competitive extraction was also investigated and then examined at different pH in order to explore the effect of the different substituent groups on metal extraction. We found high selectivity towards Fe2+(91.8%) and Pb2+(90.7%). In addition, geometry optimizations of the ground and excited-states of the selective ligands in order to get better insight into the geometry and the electronic structure were carried out by DFT and TD-DFT calculations. [ABSTRACT FROM PUBLISHER]