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An unprecedented two-step spin-crossover behavior with the sequence of γ HS =1↔γ HS =3/4↔γ HS =1/4 was observed in two-dimensional Hofmann type coordination polymer [Fe(isoq) 2 {Ag(CN) 2 } 2 ] (isoq=isoquinoline), which resulted from three crystallographically inequivalent Fe II sites with distinct transition temperatures., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report the results of investigation of high-temperature superconductor (HTSC) LaFeO F As at x = 0.15. We applied the XRD method, the measurement of the hysteresis curve and resistivity, as well as the Mössbauer measurements at the temperature range 4.2-300 K. We show that in the given sample, owing to doping by fluorine, full suppression of antiferromagnetism is not accompanied by the rise of superconductivity. Instead, we observe a high-temperature (at T ≤ 40 K) Kondo effect, which indicates a strong coupling of electron's spins with the magnetic moments of impurities. We also find a correlation between the revealed high-temperature Kondo effect and the appearance of a quadrupole splitting in the Mössbauer spectra below 40 K. The revealed effects can shed light on the mechanism of superconductivity in the iron-containing HTSC. [ABSTRACT FROM AUTHOR]

Nanofluids for high voltage insulation systems have emerged as a potential substitute for liquid dielectrics in industrial applications. Nevertheless, the sedimentation of nanoparticles has been so far a serious barrier for their wide and effective exploitation. The present work reports on the development and in-depth characterization of colloidally ultrastable natural ester oil insulation systems containing iron oxide nanocrystals which lift the problem of sedimentation and phase separation. Compared to state-of-the-art systems, the final product is endowed with increased dielectric strength, faster thermal response, lower dielectric losses (decreased dissipation factor: tan δ), and very high endurance during discharge stressing. The developed nanofluid was studied and compared with a similar system containing commercial iron oxide nanoparticles, the latter demonstrating extensive sedimentation. Herein, the dielectric properties of the nanofluids are analyzed at various concentrations by means of breakdown voltage and dissipation factor measurements. The characterization techniques unequivocally demonstrate the high performance reliability of the reported nanofluid, which constitutes a significant breakthrough in the field of high voltage insulation technologies.

In this work, we demonstrate a significant improvement in the electrical conductivity of carbon nanostructured thin films, composed of graphene nanosheets and multiwalled carbon nanotubes, by compression/polishing. It is shown that the sheet resistance of compressed thin films of carbon nanostructures and hybrids is remarkably decreased in comparison with that of as-deposited films. The number of the interconnections, the distance between the nanostructures as well as their orientation are highly altered by the compression favoring the electrical conductivity of the compressed samples.

We report on the effect of the degree of oxidation on the broadband non-linear optical response and magnetic behavior of graphene oxide, as well as on a route for obtaining reduced graphene oxide with enhanced optical properties without sacrificing the high dispersibility of the parent graphene oxide. As more sp(3) states evolved with the rise in oxidation degree, it turned out that the sp(2)/sp(3) fraction and sp(2) clustering are crucial parameters for tuning the broadband non-linear optical absorption over a wide range from ps to ns laser pulses for both visible and infrared laser irradiation. This was clearly confirmed by two different approaches, namely by a synthetic route through the gradual oxidation of graphene oxide from 1 to 3 oxidizing cycles, and reversely by in situ reduction of graphene oxide by UV laser irradiation. Furthermore, as the sp(3) states carry localized magnetic moments, ferromagnetic ordering is observed at low temperatures. The magnetization and temperature at which ferromagnetic ordering evolves are found to increase on increasing the oxidation degree. The tuning of non-linear optical and magnetic properties of graphene oxide by oxidation/reduction thus provides an easy way to endow graphene oxide with tunable physical features highly required in both optoelectronics and spintronics applications.

Two new mononuclear Fe(II) complexes, [FeL1(NCBH3)2] (1) and [FeL2(CN)2]·3H2O (2) (L1 = N,N'-bis(2-pyridylmethyl)-1,2-ethanediamine, L2 = N-(2-pyridylmethyl)-N'-(2-pyridylmethylene)-1,2-ethanediamine) were synthesized from the same starting solution under different atmospheric conditions. Complex 1 was isolated under an N2 atmosphere with an expected molecular structure, namely a tetradentate L1 ligand and two NCBH3(-) co-ligands wrapping an iron(ii) ion. It exhibits a gradual spin crossover centered around 355 K, as confirmed by X-ray crystallography, magnetic, DSC and Mössbauer studies. Complex 2 was isolated in the presence of air. One of the secondary amine groups in L1 undergoes an in situ oxidative dehydrogenation, forming a new monoimine asymmetric ligand L2. Besides, a CN(-) co-ligand is also in situ generated from NCBH3(-) during the reaction. The strong ligand field strength imposed by CN(-) and L2 stabilizes 2 in the LS state. Solvent water molecules in complex 2 are hydrogen bonded into a well-defined 1D water chain. 2 shows a proton conductivity of 8.9 × 10(-5) S cm(-1) at 55 °C and 95% relative humidity.

The most recent climate change projections show a global increase in temperatures along with precipitation changes throughout the 21(st) century. However, regional projections do not always match global projections and species with global distributions may exhibit varying regional susceptibility to climate change. Here we show the effect of local climatic conditions on the hatchling output of leatherback turtles (Dermochelys coriacea) at four nesting sites encompassing the Pacific, Atlantic and Indian Oceans. We found a heterogeneous effect of climate. Hatchling output increased with long-term precipitation in areas with dry climatic conditions (Playa Grande, Pacific Ocean and Sandy Point, Caribbean Sea), but the effect varied in areas where precipitation was high (Pacuare, Caribbean Sea) and was not detected at the temperate site (Maputaland, Indian Ocean). High air temperature reduced hatchling output only at the area experiencing seasonal droughts (Playa Grande). Climatic projections showed a drastic increase in air temperature and a mild decrease in precipitation at all sites by 2100. The most unfavorable conditions were projected for Sandy Point where hatching success has already declined over time along with precipitation levels. The heterogeneous effect of climate may lead to local extinctions of leatherback turtles in some areas but survival in others by 2100.

In this critical review, we outline various covalent and non-covalent approaches for the functionalization of iron oxide nanoparticles (IONPs). Tuning the surface chemistry and design of magnetic nanoparticles are described in relation to their applicability in advanced medical technologies and biotechnologies including magnetic resonance imaging (MRI) contrast agents, targeted drug delivery, magnetic separations and immobilizations of proteins, enzymes, antibodies, targeting agents and other biosubstances. We review synthetic strategies for the controlled preparation of IONPs modified with frequently used functional groups including amine, carboxyl and hydroxyl groups as well as the preparation of IONPs functionalized with other species, e.g., epoxy, thiol, alkane, azide, and alkyne groups. Three main coupling strategies for linking IONPs with active agents are presented: (i) chemical modification of amine groups on the surface of IONPs, (ii) chemical modification of bioactive substances (e.g. with fluorescent dyes), and (iii) the activation of carboxyl groups mainly for enzyme immobilization. Applications for drug delivery using click chemistry linking or biodegradable bonds are compared to non-covalent methods based on polymer modified condensed magnetic nanoclusters. Among many challenges, we highlight the specific surface engineering allowing both therapeutic and diagnostic applications (theranostics) of IONPs and magnetic/metallic hybrid nanostructures possessing a huge potential in biocatalysis, green chemistry, magnetic bioseparations and bioimaging., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Three new two-dimensional (2D) Hofmann-type coordination polymers with general formula [Fe(3-NH2py)2M(CN)4] (3-NH2py = 3-aminopyridine, M = Ni (1), Pd (2), Pt (3)) have been synthesized. Magnetic susceptibility measurements show that they exhibited cooperative spin crossover (SCO) with remarkable hysteretic behaviors. Their hysteresis widths are 25, 37, and 30 K for 1-3, respectively. The single-crystal structure of 1 suggest that the pseudo-octahedral Fe sites are equatorially bridged by [M(CN)4](2-) to form 2D grids and axially coordinated by 3-NH2py ligands. The intermolecular interactions between layers (the offset face-to-face π···π interactions, hydrogen bonds, and weak N(amino)···Ni(II) contacts) together with the covalent bonds bridged by [M(CN)4](2-) units are responsible to the significant cooperativity.

The increasing challenges posed by plant viral diseases demand innovative and sustainable management strategies to minimize agricultural losses. Exogenous double-stranded RNA (dsRNA)-mediated RNA interference (RNAi) represents a transformative approach to combat plant viral pathogens without the need for genetic transformation. This review explores the mechanisms underlying dsRNA-induced RNAi, highlighting its ability to silence specific viral genes through small interfering RNAs (siRNAs). Key advancements in dsRNA production, including cost-effective microbial synthesis and in vitro methods, are examined alongside delivery techniques such as spray-induced gene silencing (SIGS) and nanocarrier-based systems. Strategies for enhancing dsRNA stability, including the use of nanomaterials like layered double hydroxide nanosheets and carbon dots, are discussed to address environmental degradation challenges. Practical applications of this technology against various plant viruses and its potential to ensure food security are emphasized. The review also delves into regulatory considerations, risk assessments, and the challenges associated with off-target effects and pathogen resistance. By evaluating both opportunities and limitations, this review underscores the role of exogenous dsRNA as a sustainable solution for achieving viral disease resistance in plants. [ABSTRACT FROM AUTHOR]

Background: Nanomaterials compounded with entomopathogenic fungi have been proven to be effective in insect pest management. This study reports the synthesis and bioactivity of Isaria fumosorosea-based nanoparticles by compounding the fungus with differentially (positively or negatively) charged carbon dots. Initially, negatively charged carbon dots (N-CDs) and carbon dots (P-CDs) were synthesized via a one-step hydrothermal method. The N-CDs and P-CDs were then individually compounded with I. fumosorosea to develop N-CD@I. fumosorosea and P-CD@I. fumosorosea nanocomposites. Results: Characterization of the nanoparticles revealed that positively or negatively charged carbon dots were attached to I. fumosorosea by electrostatic bonding. Finally, the virulence of both types of nanoparticles was observed in Plutella xylostella. The bioassay results indicated that the highest P. xylostella mortality (92.7 ± 2.04%) was associated with the P-CD@I. fumosorosea treatment. The results of nontargeted metabolomic analysis revealed that different treatments affected the metabolism of P. xylostella by interfering with the riboflavin metabolism pathway by downregulating the expression of two main metabolites of the riboflavin metabolism pathway (2-5-diamino-6-pyrimidin-4-one and 7-hydroxy-6-methyl-8-ribiotin), although the extent of the expression downregulation varied among the different treatments. Conclusion: Overall, this work provides insight into the mechanism by which positively charged nanomaterials improve the virulence of entomopathogenic fungi. This work provides a new direction for the design and application of nanomaterials for insect pest management. [ABSTRACT FROM AUTHOR]

Banana peel is biomass that can be converted into activated carbon. Changing activated carbon from banana peel biomass would eventually become an innovation, bringing biomass to prominence as a new and renewable energy source. Electromagnetic waves are another approach for activating carbon. Gamma irradiation functions as an ionization agent or initiator, resulting in the production of free radicals. Gamma electromagnetic exposure provides clean energy with no production of chemical components. The purpose of this experiment was to investigate the effect of 60Co gamma irradiation on the chemical functional group, surface area, diameter porous formation, and morphology of carbon at 10 to 50 kGy gamma radiation exposure using FTIR, BET, and SEM instrumentation. The results revealed that modification of activated carbon by irradiation and surfactant has a substantial effect on the formation of diameter pores, functional group formation, and porosity structure. The result showed that gamma irradiation exposure significantly affected pore distribution formation on activated carbon because of cellulose decomposition. Gamma irradiation treatment with optimum doses of 30 and 40 kGy on AC/SLS increased the adsorption capacity of Pb2+ to 54.31% and 52.67% compared to AC/SLS without irradiation at 41.65%. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) is one of the most critical reactions in energy conversion systems, and it facilitates the efficient conversion of chemical energy into electrical energy, which is necessary for modern technology. Developing efficient and cost-effective catalysts for ORRs is crucial for advancing and effectively applying renewable energy technologies such as fuel cells, metal–air batteries, and electrochemical sensors. In recent years, iron porphyrin-based composites have emerged as ideal catalysts for facilitating effective ORRs due to their unique structural characteristics, abundance, advances in synthesis, and excellent catalytic properties, which mimic natural enzymatic systems. However, many articles have focused on reviewing porphyrin-based frameworks or metalloporphyrins in general, necessitating research specifically addressing iron porphyrin. This review discusses iron porphyrin as an effective catalyst in ORRs. It provides a comprehensive knowledge of the application of iron porphyrin-based composites for electrocatalytic ORRs, focusing on their properties, synthesis, structural integration with conductive supports, catalytic mechanism, and efficacy. This review also discusses the challenges of applying iron porphyrin-based composites and provides recommendations to address these challenges. [ABSTRACT FROM AUTHOR]

The development of effective catalytic systems for deoxygenation reactions is critical to the conversion of renewable feedstocks into sustainable fuels. In this work, the influence of various reaction parameters on the conversion of palmitic acid into alkanes, such as temperature, stirring rate, reaction time, H2 pressure, amount of catalyst and substrate concentration was evaluated using the commercial Co-Mo/Al2O3 catalyst. In parallel, bimetallic Co-Mo catalysts supported on carbon nanotubes (CNTs) were prepared and characterized using various techniques, and their catalytic performance was assessed under the optimized conditions. The results showed that palmitic acid can be efficiently converted at 350 °C for 6 h at 30 bar H2 pressure, stirring at 150 rpm and using 0.25 g of catalyst and 0.50 g of palmitic acid in 50 mL of n-decane. Under these conditions, a complete substrate conversion and yields of 89.4 and 4.8% of C16 and C15 were achieved. In addition, Co-Mo/CNTox presented a similar catalytic performance as the commercial one, with a final result of 90.9% yield in C16. These findings point out the potential of using Co-Mo/CNTox as a competitive alternative to liquid fuel production. [ABSTRACT FROM AUTHOR]

Marine turtles are iconic, globally distributed large reptiles with a largely oceanic life history that makes it difficult to characterize population demography and dynamics. This is significant because all marine turtle species are currently considered vulnerable or endangered. Knowledge of the age of individuals is central to our understanding of the life history of a species and an important consideration in the design of management and conservation strategies. Herein, we review different methods used to estimate the absolute, relative and physiological age of marine turtles, as well as their underlying hypotheses and challenges in their interpretation. We conclude that, at present, there is no validated method that establishes the absolute age of an individual from field studies. [ABSTRACT FROM AUTHOR]

A chiral metal-organic framework exhibiting spin crossover (SCO) property, [Fe(II)(mptpy)2]·EtOH·0.2DMF (·solv), has been solvothermally synthesized through spontaneous resolution. It displays remarkable stability and two-step SCO at (Tc1 = 200 K) and above (Tc2 = 357 K) room temperature.

A novel core-shell nanomaterial based on prussian blue (PB) coating on peculiar surface active maghemite nanoparticles (SAMNs), was developed. The synthetic process involves the direct crystallization of Fe(II)(CN)6(4-) onto the surface of SAMNs by simple incubation in water at controlled pH, demonstrating the presence of under-coordinated Fe(III) on nanoparticle surface. The coating reaction occurs in a narrow pH range and the synthetic procedure was optimized. The resulting SAMN@PB hybrid nanostructures were characterized by transmission and scanning electron microscopy, Mössbauer, UV-vis and FTIR spectroscopy and X-ray powder diffraction. The nanomaterial, characterized by high stability in alkaline media, behave as excellent electro-catalyst for hydrogen peroxide reduction. The stability of SAMN@PB hybrid has been investigated as a function of pH, showing excellent stability up to pH 9.0 and demonstrating the feasibility of SAMNs, superficially derivatized with prussian blue, to produce an efficient and extremely stable nanostructured material. This maghemite supported nanostructured prussian blue was applied to develop a sensor, based on a simple carbon paste electrode, which was able to catalyze the electro-reduction of hydrogen peroxide, in aqueous solutions, buffered at pH 7.0, at low applied potentials (0.0 V vs. SCE)., (© 2013 Elsevier B.V. All rights reserved.)

MCM-41-supported nanoscale zero-valent iron (nZVI) was sytnhesized by impregnating the mesoporous silica martix with ferric chloride, followed by chemical reduction with NaHB4. The samples were studied with a combination of characterization techniques such as powder X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and Mössbauer spectroscopy, N2 adsorption measurements, transmission electron microscopy (TEM), magnetization measurements, and thermal analysis methods. The experimental data revealed development of nanoscale zero-valent iron particles with an elliptical shape and a maximum size of ∼80 nm, which were randomly distributed and immobilized on the mesoporous silica surface. Surface area measurements showed that the porous MCM-41 host matrix maintains its hexagonal mesoporous order structure and exhibits a considerable high surface area (609 m(2)/g). Mössbauer and magnetization measurements confirmed the presence of core-shell iron nanoparticles composed of a ferromagnetic metallic core and an oxide/hydroxide shell. The kinetic studies demonstrated a rapid removal of Cr(VI) ions from the aqueous solutions in the presence of these stabilized nZVI particles on MCM-41, and a considerably increased reduction capacity per unit mass of material in comparison to that of unsupported nZVI. The results also indicate a highly pH-dependent reduction efficiency of the material, whereas their kinetics was described by a pseudo-first order kinetic model., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Hierarchical assembly of Ti(IV)/Sn(II)-doped SnO₂ nanosheets along titanate nanowires serving as both sacrificial templates and a Ti(IV) source is demonstrated, using SnCl2 as a tin precursor and Sn(II) dopants and NaF as the morphology controlling agent. Excess fluoride inhibits the hydrolysis of SnCl2, promoting heterogeneous nucleation of Sn(II)-doped SnO₂ on the titanate nanowires due to the insufficient oxidization of Sn(II) to Sn(IV). Simultaneously, titanate nanowires are dissolved forming Ti(4+) species under the etching effect of in situ generated HF resulting in spontaneous Ti(4+) ion doping of SnO₂ nanosheets formed under hydrothermal conditions. Compositional analysis indicates that Ti(4+) ions are incorporated by substitution of Sn sites at a high level (16-18 at.%), with uniform distribution and no phase separation. Mössbauer spectroscopy quantified the relative content of Sn(II) and Sn(IV) in both Sn(II)-doped and Ti(IV)/Sn(II) co-doped SnO₂ samples. Electrochemical properties were investigated as an anode material in lithium ion batteries, demonstrating that Ti-doped SnO₂ nanosheets show improved cycle performance, which is attributed to the alleviation of inherent volume expansion of the SnO₂-based anode materials by substituting part of Sn sites with Ti dopants.

Biomimetic complexes are artificially engineered molecules that aim to reduce the structural complexity of biological systems in order to unveil the key electronic and structural factors relevant to a protein's function. In this work, a novel coordination compound (L2Fe2) which mimics non-heme binuclear proteins was synthesized from the Schiff-base ligand HL = (E)-N′-(phenyl(pyridin-2-yl)methylene)isonicotinohydrazide. The crystal structure of L2Fe2 showed that the intramolecular Fe–Fe distances (3.1–3.2 Å) were analogous to those found in non-heme binuclear ferric proteins. However, in L2Fe2, two methoxide groups act as bridging units for oxidized iron (Fe3+). Such a bridging motif is unprecedented in the biological realm. Magnetic susceptibility measurements demonstrated that L2Fe2 is characterized by a singlet (S = 0) ground state and a very small magnetic coupling constant J (≪ −1 cm(−1)). The J value featured by L2Fe2 differs considerably from the values observed in non-heme binuclear proteins in the oxidized form (−100 cm(−1) < J < −10 cm(−1)), which encompass oxo/hydroxo and carboxylate bridging residues. The singlet ground state of L2Fe2 as well as the weak magnetic interaction between the two ferric cations was successfully predicted by density functional theory (DFT).

Carbon dots (CDs) are nanoparticles (NPs) used in cancer treatment for medical imaging and drug delivery. This research examines the characteristics of carbon quantum dots (CQDs) that make them suitable for medical purposes. CQDs, consisting of carbon atoms with unique properties, are less than 10 nm in size and possess biocompatibility and energy release capabilities. Recent advancements in utilizing CQDs for bioimaging and therapy, including light-based treatments and antibacterial therapies, are discussed. The study also emphasizes the importance of monitoring, self-transformation, and future advancements in biological applications to obtain regulatory approval for clinical use, such as from the FDA. The research provides a detailed analysis of CQDs’ biomedical applications, highlighting their dispersibility, compatibility, and photoluminescent properties for applications such as drug delivery, biosensing, and controlled release. Various synthetic methods for different types of CQDs, including modified versions, are explored, along with investigations into pharmacokinetics, toxicity profiles, and implications in clinical and biological settings. Overall, this study offers a comprehensive understanding of CQDs’ synthesis, modification, pharmacokinetics, toxicity, polymer composite, and future research directions for bioimaging applications. [ABSTRACT FROM AUTHOR]

Core-shell hydrophilic superparamagnetic iron oxide (SPIO) nanoparticles, surface functionalized with either terephthalic acid or 2-amino terephthalic acid, showed large negative MRI contrast ability, validating the advantage of using low molecular weight and π-conjugated canopies for engineering functional nanostructures with superior performances.

Hybrid magnetic drug nanocarriers are prepared via a self-assembly process of poly(methacrylic acid)-graft-poly(ethyleneglycol methacrylate) (p(MAA-g-EGMA)) on growing iron oxide nanocrystallites. The nanocarriers successfully merge together bio-repellent properties, pronounced magnetic response, and high loading capacity for the potent anticancer drug doxorubicin (adriamicin), in a manner not observed before in such hybrid colloids. High magnetic responses are accomplished by engineering the size of the magnetic nanocrystallites (∼13.5 nm) following an aqueous single-ferrous precursor route, and through adjustment of the number of cores in each colloidal assembly. Complementing conventional magnetometry, the magnetic response of the nanocarriers is evaluated by magnetophoretic experiments providing insight into their internal organization and on their response to magnetic manipulation. The structural organization of the graft-copolymer, locked on the surface of the nanocrystallites, is further probed by small-angle neutron scattering on single-core colloids. Analysis showed that the MAA segments selectively populate the area around the magnetic nanocrystallites, while the poly(ethylene glycol)-grafted chains are arranged as protrusions, pointing towards the aqueous environment. These nanocarriers are screened at various pHs and in highly salted media by light scattering and electrokinetic measurements. According to the results, their stability is dramatically enhanced, as compared to uncoated nanocrystallites, owing to the presence of the external protective PEG canopy. The nanocarriers are also endowed with bio-repellent properties, as evidenced by stability assays using human blood plasma as the medium., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Superparamagnetic nanoparticles (20-40 nm) of maghemite, γ-Fe(2)O(3), with well-defined stoichiometric structure, are synthesized by the borohydride reduction of ferric chloride at an elevated temperature (100°C) followed by thermal treatment of the reaction product. Prepared maghemite nanoparticles reveal excellent colloidal stability for a long time without the necessity for any additional surface modification. These colloidal features are due to surface stabilizing OH(-) groups, which act as charge barriers preventing a particle aggregation and enabling a reversible binding of various oppositely charged organic substances. Such binding with rhodamine B isothiocyanate results in the fluorescent magnetic nanocarrier providing, at the same time, a spacer arm for covalent immobilization of other biosubstances including enzymes. In this work, we exploit this general applicability of the developed nanocarrier for covalent immobilization of glucose oxidase. This is the first reported example of magnetically drivable fluorescent nanocatalyst. The immobilized enzyme creates a 3-5 nm thick layer on the nanoparticle surface as proved by high-resolution transmission electron microscopy. This layer corresponds to 10 enzyme molecules, which are bound to the nanoparticle surface as found by the fluorimetric determination of flavin adenine dinucleotide. The developed magnetic fluorescent nanocatalyst, showing a rate constant of 32.7s(-1) toward glucose oxidation, can be used as a biosensor in various biochemical, biotechnological, and food chemistry applications. The presence of the nanocatalyst can be simply monitored by its fluorescence; moreover, it can be easily separated from the solution by an external magnetic field and repeatedly used without a loss of catalytic efficiency., (Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Nanoscale zero-valent iron (nZVI) particles and a composite containing a mixture of ferrate(VI) and ferrate(III) were prepared by thermal procedures. The phase compositions, valence states of iron, and particle sizes of iron-bearing compounds were determined by combination of X-ray powder diffraction, Mössbauer spectroscopy and scanning electron microscopy. The applicability of these environmentally friendly iron based materials in treatment of chemical warfare agents (CWAs) has been tested with three representative compounds, sulfur mustard (bis(2-chlorethyl) sulfide, HD), soman ((3,3'-imethylbutan-2-yl)-methylphosphonofluoridate, GD), and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothiolate (VX). Zero-valent iron, even in the nanodimensional state, had a sluggish reactivity with CWAs, which was also observed in low degrees of CWAs degradation. On the contrary, ferrate(VI)/(III) composite exhibited a high reactivity and complete degradations of CWAs were accomplished. Under the studied conditions, the estimated first-order rate constants (≈ 10(-2)s(-1)) with the ferrate(VI)/(III) composite were several orders of magnitude higher than those of spontaneous hydrolysis of CWAs (10(-8)-10(-6)s(-1)). The results demonstrated that the oxidative technology based on application of ferrate(VI) is very promising to decontaminate CWAs., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Cyanobacteria pose a serious threat to water resources around the world. This is compounded by the fact that they are extremely resilient, having evolved numerous protective mechanisms to ensure their dominant position in their ecosystem. We show that treatment with nanoparticles of zerovalent iron (nZVI) is an effective and environmentally benign method for destroying and preventing the formation of cyanobacterial water blooms. The nanoparticles have multiple modes of action, including the removal of bioavailable phosphorus, the destruction of cyanobacterial cells, and the immobilization of microcystins, preventing their release into the water column. Ecotoxicological experiments showed that nZVI is a highly selective agent, having an EC(50) of 50 mg/L against cyanobacteria; this is 20-100 times lower than its EC(50) for algae, daphnids, water plants, and fishes. The primary product of nZVI treatment is nontoxic and highly aggregated Fe(OH)(3), which promotes flocculation and gradual settling of the decomposed cyanobacterial biomass.

Sustainable hydrogen production through photoelectrochemical water splitting using hematite (alpha-Fe(2)O(3)) is a promising approach for the chemical storage of solar energy, but is complicated by the material's nonoptimal optoelectronic properties. Nanostructuring approaches have been shown to increase the performance of hematite, but the ideal nanostructure giving high efficiencies for all absorbed light wavelengths remains elusive. Here, we report for the first time mesoporous hematite photoelectodes prepared by a solution-based colloidal method which yield water-splitting photocurrents of 0.56 mA cm(-2) under standard conditions (AM 1.5G 100 mW cm(-2), 1.23 V vs reversible hydrogen electrode, RHE) and over 1.0 mA cm(-2) before the dark current onset (1.55 V vs RHE). The sintering temperature is found to increase the average particle size, and have a drastic effect on the photoactivity. X-ray photoelectron spectroscopy and magnetic measurements using a SQUID magnetometer link this effect to the diffusion and incorporation of dopant atoms from the transparent conducting substrate. In addition, examining the optical properties of the films reveals a considerable change in the absorption coefficient and onset properties, critical aspects for hematite as a solar energy converter, as a function of the sintering temperature. A detailed investigation into hematite's crystal structure using powder X-ray diffraction with Rietveld refinement to account for these effects correlates an increase in a C(3v)-type crystal lattice distortion to the improved optical properties.

Hybrid nanocolloids based on biodegradable polymers of poly(lactide) (PLA) or poly(lactide)-block-poly(ethylene glycol) (PLA-PEG) and hydrophobic iron oxide magnetic nanoparticles (MNPs) of ca. 5 nm are prepared via a self-assembly route. The magnetic nanoparticles are organized in superclusters inside the hydrophobic core of PLA-PEG micelles or cholate-stabilized PLA nanospheres. The hydrodynamic diameter of MNPs-loaded PLA nanospheres is approximately 250 nm, whereas that of MNPs-loaded PLA-PEG micelles is much lower (approximately 100 nm) and thus compatible with applications where prolonged blood circulation is required. The PLA-PEG micelles exhibit high encapsulation efficiency for the MNPs, imparting a saturation magnetization value to the hybrid of 8.4 emu g(-1). Both hybrid colloids display magnetic properties of a non-interacting assembly of superparamagnetic particles and a low blocking temperature, both of which are key attributes for colloidally stable ferrofluids. Furthermore, the PLA-PEG magnetic hybrids display remarkable colloidal stability at high ionic strength, temperature and in human blood plasma, while the estimated critical micelle concentration of ca. 2 x 10(-5) mM (0.3 mg L(-1)) indicates the low probability of the colloids dissociation in the blood compartment. They were also found to be non-toxic to human cells in vitro. The results underline the potential of the magnetic/PLA-PEG hybrids and encourage further research for their in vivo biomedical applications.

Magnetic nanocomposites containing iron oxide (maghemite) nanoparticles, well embedded in a synthetic clay matrix (laponite) were prepared by a new one step chemical route and characterized by TEM, XRD, magnetization measurements, Mössbauer spectroscopy, DLS, and MRI measurements. The synthetic procedure leads to non-stoichiometric γ-Fe(2)O(3) with a controllable content in the nanocomposite. Magnetic nanoparticles incorporated in the diamagnetic clay matrix exhibit a mean diameter of 13 nm, superparamagnetic behavior with a high saturation magnetization achievable at low applied magnetic fields. In-field Mössbauer spectra and ZFC/FC magnetization curves reveal a perfect ferrimagnetic ordering within nanoparticles with negligible spin frustration and interparticle interactions due to the complete coating of maghemite surfaces by the nanocrystalline laponite matrix. Magnetic iron oxide nanoparticles embedded in laponite matrix exhibit strong T(2) weighted MRI contrast. The maghemite/laponite composite particles have 200 nm hydrodynamic diameter and form very stable hydrosols and/or hydrogels depending on their concentration in water.