A rational study of the influence of Mn2+-insertion in Prussian blue nanoparticles on their photothermal properties.

We investigated a series of Mn2+-Prussian blue (PB) nanoparticles NazMnxFe1-x[Fe(CN)6]1-y□y·nH2O of similar size, surface state and cubic morphology with various amounts of Mn2+ synthesized through a one step self-assembly reaction. We demonstrated by a combined experimental-theoretical approach that during the synthesis, Mn2+ substituted Fe3+ up to a Mn/Na-Mn-Fe ratio of 32 at% in the PB structure, while for higher amounts, the Mn2[Fe(CN)6] analogue is obtained. For comparison, the post-synthetic insertion of Mn2+ in PB nanoparticles was also investigated and completed with Monte-Carlo simulations to probe the plausible adsorption sites. The photothermal conversion efficiency (η) of selected samples was determined and showed a clear dependence on the Mn2+amount with a maximum efficiency for a Mn/Na-Mn-Fe ratio of 10 at% associated with a dependence on the nanoparticle concentration. Evaluation of the in vitro photothermal properties of these nanoparticles performed on triple negative human breast adenocarcinoma (MDA-MB-231) cells by using continuous and pulsed laser irradiation confirm their excellent PTT efficiency permitting low dose use.

Formation and transformation of manganese(III) intermediates in the photochemical generation of manganese(IV) oxide minerals.

As important natural oxidants and adsorbents, manganese (Mn) oxide minerals affect the speciation, bioavailability and fate of pollutants and nutrient elements. It was found that birnessite-type Mn(IV) oxide minerals can be formed in the presence of NO3- and solar irradiation. However, the photochemical formation and transformation processes from Mn2+ to Mn(IV) oxide minerals remain unclear. In this work, the Mn(IV) oxide minerals were confirmed to be photochemically formed mainly due to the disproportionation of Mn(III) intermediates generated from the oxidation of Mn2+ in the presence of NO3- under UV light irradiation. The oxidation rate of Mn2+ to Mn(IV) oxide minerals decreased with increasing initial Mn2+ concentration due to the lower disproportionation rate. The increase in NO3- concentration, pH and temperature promoted Mn2+ photochemical oxidation. The photochemical formation rate of Mn(IV) oxide minerals increased with increasing ligand concentrations at low ligand concentrations. Ligands affected the formation of Mn(IV) oxide minerals by promoting the formation and reducing the reactivity of Mn(III) intermediates. Overall, this work reveals the important role of Mn(III) intermediates in the formation of natural Mn oxide minerals.

Physical assessments of termites (Termitidae) under 2.45 GHz microwave irradiation.

Demands for chemical-free treatments for controlling insect pests are increasing worldwide. One such treatment is microwave heating; however, two critical issues arise when using microwaves as a heat source: intensive labor and excessive energy-consumption. Optimization is thus required to reduce energy consumption while effectively killing insects. Currently, the lethal effect of microwaves on insects is considered to be due to the temperature of the irradiated materials. This study examines how the conditions of irradiation, such as resonance or traveling mode, changed the conversion of electromagnetic energy into heat when 2.45 GHz microwaves penetrated the body of the termite, C. formosanus. Our results indicated that it is possible to heat and kill termites with microwaves under resonance condition. Termites were however found to be very tolerant to microwave irradiation as the permittivity of the insect was low compared with other reported insects and plants. Electron spin resonance revealed that termites contained several paramagnetic substances in their bodies, such as Fe3+, Cu2+, Mn2+, and organic radicals. Interestingly, irradiation with traveling microwaves hardly produced heat, but increased the organic radicals in termite bodies indicating non-thermal effects of microwaves.

Local Structure Modulation Induced Highly Efficient Far-Red Luminescence of La1- xLu xAlO3:Mn4+ for Plant Cultivation.

Modulating the local environment around the emitting ions with component screening to increase the quantum yield and thermal stability is an effective and promising strategy for the design of high-performance fluorescence materials. In this work, smaller Lu3+ was introduced into the La3+ site in a Mn4+-activated LaAlO3 phosphor with the expectation of improving the luminescence properties via lattice contraction induced by cation substitution. Finally, a La1- xLu xAlO3:Mn4+ ( x = 0-0.04) perovskite phosphor with a high quantum yield of 86.0% and satisfactory thermal stability was achieved, and the emission peak at 729 nm well matches with the strongest absorption peak of the Phytochrome PFR. The favorable performances could be attributed to the suppressed cell volume and superior lattice rigidity after the substitution of Lu3+. This work not only obtains a highly efficient La1- xLu xAlO3:Mn4+ ( x = 0.02) phosphor, which holds great potential for application in plant-cultivation light-emitting diodes, but also provides an applicable strategy for further investigation of far-red-emitting phosphors.

SYNTHESIS, OPTICAL PROPERTIES AND THERMOLUMINESCENCE DOSIMETRY FEATURES OF MANGANESE DOPED Li2B4O7 NANOPARTICLES.

Lithium tetraborate (Li2B4O7) nanoparticles (NPs) doped with manganese (Mn) were prepared for the first time by the solid-state sintering method. NPs were characterized using X-ray diffraction, scanning electron microscopy, photoluminescence and thermoluminescence (TL) techniques. The synthesized NPs exhibited highest TL response at 0.3 wt% of Mn dopant under gamma irradiation. TL dose response is linear for the absorbed dose from 1 Gy to 20 kGy and beyond this range behaves sub-linear. Such feature makes the synthesized nanophosphor as a promising material for high-dose dosimetry applications. Low fading and good reusability were obtained for the synthesized NPs. Tm-Tstop and computerized glow curve deconvolution procedures were utilized to identify the component TL glow peaks and kinetic parameters of the produced phosphor. Other TL dosimetry features of the prepared NPs are also presented and discussed.

QA measurement of gamma-ray dose and neutron activation using TLD-400 for BNCT beam.

TLD-400 (CaF2:Mn) chips were applied for the gamma-ray dose measurement in a PMMA phantom exposed to a BNCT beam because of their very low neutron sensitivity. Since TLD-400 chips possess an adequate amount of Mn activator they have been employed in this work simultaneously for neuron activation measurement. The self-irradiation TL signals owing to the decay of the neutron induced 56Mn activity have been applied for a calibration of the TLD-400 chip in situ, where the activities were measured by an HPGe detector system and the energy deposition per disintegration of 56Mn was calculated by applying a Monte Carlo code. It was accidentally found that the irradiated TLD-400 chips were capable of emitting prominent scintillation lights owing to the induced 56Mn activity, which can easily be recorded by the TLD reader without heating and after a calibration can be used to determine the 56Mn activity.

The water soluble peripherally tetra-substituted zinc(ii), manganese(iii) and copper(ii) phthalocyanines as new potential anticancer agents.

In this study, [2-(2-morpholin-4-ylethoxy)ethoxy] group substituted zinc(ii), manganese(iii) and copper(ii) phthalocyanines 2-4 and their water soluble derivatives 2a, 3a and 4a were synthesized and the interactions of compounds 2a, 3a and 4a with CT-DNA and supercoiled pBR322 plasmid DNA were investigated. The results of binding experiments showed that these compounds were able to interact with CT-DNA via intercalative mode with a strong binding affinity in the order 3a > 2a > 4a. DNA-photocleavage activities of compounds 2a, 3a and 4a were determined. These compounds cleaved supercoiled pBR322 plasmid DNA efficiently under irradiation at 650 nm for 2a and 4a, and at 750 nm for 3a. These compounds displayed remarkable inhibitory activities against topoisomerase I enzyme in a dose-dependent manner. All of these results suggest that these phthalocyanines might be suitable anticancer agents due to their strong binding affinities, significant cleavage activities and effective topoisomerase I inhibition.

Light-triggered CO delivery by a water-soluble and biocompatible manganese photoCORM.

The discovery of salutary effects of low doses of carbon monoxide (CO) has spurred interest in designing exogenous molecules that can deliver CO to biological targets under controlled conditions. Herein we report a water-soluble photosensitive manganese carbonyl complex [MnBr(CO)3(pyTAm)] (2) (pyTAm = 2-(pyridyl)imino-triazaadamantane) that can be triggered to release CO upon exposure to visible light. Inclusion of a triazaadamantyl pharmacophore into the coligand of 2 improves its stability and solubility in water. Change in the coligand from 2-(pyridyl)imino-triazaadamantane to 2-(pyridyl)iminoadamantane (pyAm) or 2-(quinonyl)imino-triazaadamantane (qyTAm) dramatically alters these desired properties of the photoCORM. In addition to structures and CO-releasing properties of the three analogous complexes 1-3 from these three α-diimine ligands, theoretical calculations have been performed to determine the origin of Mn-CO bond labilization upon illumination. Rapid delivery of CO to myoglobin under physiological conditions attests the potential of 2 as a biocompatible photoCORM.

Uncaging a catalytic hydrogen peroxide generator through the photo-induced release of nitric oxide from a {MnNO}(6) complex.

The photo-initiated cytotoxicity of a newly developed manganese nitrosyl {MnNO}(6) complex (UG1NO) to HeLa cells is described. The complex was found to be strongly cytotoxic after being exposed to light with a wavelength of 650 nm. Cell death was caused by a manganese(II) complex, UG1, generated from UG1NO through the photo-dissociation of NO, rather than by NO directly. Mechanistic studies revealed that UG1 consumes O2 only in the presence of a reducing agent to catalytically produce H2O2.

Radiation-induced defects in manganese-doped lithium tetraborate phosphor.

Lithium tetraborate doped with manganese synthesised by solid-state sintering technique exhibits a dosimetric peak at 280°C. The high-temperature glow curve results in no fading for three months. The sensitivity of Li2B4O7:Mn is determined to be 0.9 times that of TLD-100. The infrared spectrum of this phosphor indicates the presence of bond vibrations corresponding to BO4 tetrahedral and BO3 triangles. The mechanism for thermoluminescence in this phosphor was proposed based on the thermoluminescence (TL) emission spectra, kinetic analysis of TL glow curves and electron paramagnetic resonance (EPR) measurements on non-irradiated and gamma-irradiated phosphors. It was identified that oxygen vacancies and Boron oxygen hole centre (BOHC) are the electron and hole trap centres for TL in this phosphor. When the phosphor is heated, the electrons are released from the electron trap and recombine with the trapped holes. The excitation energy during the recombination is transferred to the nearby Mn(2+) ions, which emit light at 580 nm.

Non-adiabatic molecular dynamics investigation of photoionization state formation and lifetime in Mn²âº-doped ZnO quantum dots.

The unique electronic structure of Mn(2+)-doped ZnO quantum dots gives rise to photoionization states that can be used to manipulate the magnetic state of the material and to generate zero-reabsorption luminescence. Fast formation and long non-radiative decay of this photoionization state is a necessary requirement for these important applications. In this work, surface hopping based non-adiabatic molecular dynamics are used to demonstrate the fast formation of a metal-to-ligand charge transfer state in a Mn(2+)-doped ZnO quantum dot. The formation occurs on an ultrafast timescale and is aided by the large density of states and significant mixing of the dopant Mn(2+) 3dt2 levels with the valence-band levels of the ZnO lattice. The non-radiative lifetime of the photoionization states is also investigated.

Introducing [Mn(CO)3(tpa-κ(3)N)](+) as a novel photoactivatable CO-releasing molecule with well-defined iCORM intermediates - synthesis, spectroscopy, and antibacterial activity.

[Mn(CO)3(tpa-κ(3)N)]Br was prepared as a novel photoactivatable CO-releasing molecule (PhotoCORM) from [MnBr(CO)5] and tris(2-pyridylmethyl)amine (tpa) for the delivery of carbon monoxide to biological systems, with the κ(3)N binding mode of the tetradentate tpa ligand demonstrated by X-ray crystallography. The title compound is a CORM prodrug stable in solution in the dark for up to 16 h. However, photoactivation at 365 nm leads to CO release from the metal coordination sphere and transfer to haem proteins, as demonstrated by the standard myoglobin assay. Different iCORM intermediates could be detected with solution IR spectroscopy and assigned using DFT vibrational calculations. The antibacterial activity of the complex was studied on Escherichia coli. No effects were observed when the cultures were either kept in the dark in the presence of PhotoCORM or illuminated in the absence of metal complex. However, photoactivation of [Mn(CO)3(tpa-κ(3)N)]Br at 365 nm led to the appearance of the spectral signatures of CO-coordinated haems in the terminal oxidases of the bacterial electron transport chain in whole-cell UV/Vis absorption spectra. Significant internalization of the PhotoCORM was demonstrated by ICP-MS measurement of the intracellular manganese concentration. In particular when using medium with succinate as the sole carbon source, a very pronounced and concentration-dependent decrease in the E. coli growth rate could be observed upon illumination in the presence of metal complex, which is attributed to the constrained energy metabolism under these conditions and a strong indicator of terminal oxidase inhibition by carbon monoxide delivered from the PhotoCORM.

Recent advances in nanosized Mn-Zn ferrite magnetic fluid hyperthermia for cancer treatment.

This paper reviews the recent research and development of nanosized manganese zinc (Mn-Zn) ferrite magnetic fluid hyperthermia (MFH) for cancer treatment. Mn-Zn ferrite MFH, which has a targeted positioning function that only the temperature of tumor tissue with magnetic nanoparticles can rise, while normal tissue without magnetic nanoparticles is not subject to thermal damage, is a promising therapy for cancer. We introduce briefly the composition and properties of magnetic fluid, the concept of MFH, and features of Mn-Zn ferrite magnetic nanoparticles for MFH such as thermal bystander effect, universality, high specific absorption rate, the targeting effect of small size, uniformity of hyperthermia temperature, and automatic temperature control and constant temperature effect. Next, preparation methods of Mn-Zn ferrite magnetic fluid are discussed, and biocompatibility and biosecurity of Mn-Zn ferrite magnetic fluid are analyzed. Then the applications of nanosized Mn-Zn ferrite MFH in cancer are highlighted, including nanosized Mn-Zn ferrite MFH alone, nanosized Mn-Zn ferrite MFH combined with As2O3 chemotherapy, and nanosized Mn-Zn ferrite MFH combined with radiotherapy. Finally, the combination application of nanosized Mn-Zn ferrite MFH and gene-therapy is conceived, and the challenges and perspectives for the future of nanosized Mn-Zn ferrite MFH for oncotherapy are discussed.

Electric-field-modulated exchange coupling within and between magnetic clusters on metal surfaces: Mn dimers on Cu(1 1 1).

The effects of external electric fields (EFs) on the magnetic state and substrate-mediated magnetic coupling between Mn dimers on Cu(1 1 1) have been studied using a first-principles theoretical method. The calculations show that a change in the ground-state magnetic order, from antiferromagnetic (AF) to ferromagnetic (FM), can be induced within an isolated Mn2 on Cu(1 1 1) by applying a moderately strong EF of about 1 V Å(-1). The magnetic exchange coupling between pairs of dimers displays Ruderman-Kittel-Kasuya-Yosida-like oscillations as a function of the interdimer distance, which depend significantly on the magnetic order within the dimers (FM or AF) and on their relative orientation on the surface. Moreover, it is observed that applying EFs allows modulation of the exchange coupling within and between the clusters as a function of the intercluster distance. At short distances, AF order within the dimers is favoured even in the presence of EFs, while for large distances the EF can induce a FM order. EFs pointing outwards and inwards with respect to the surface favour parallel and antiparallel magnetic alignment between the dimers, resspectively. The dependence of the substrate-mediated interaction on the magnetic state of Mn2 is qualitatively interpreted in terms of the differences in the scattering of spin-polarized surface electrons.

Manganese carbonyl terpyridyl complexes: their synthesis, characterization and potential application as CO-release molecules.

Mn(I) carbonyl terpyridyl complexes have been synthesized and characterized. The tricarbonyl derivative exhibits interesting behaviors for controlled CO-release by both thermal and photosynthetic pathways.

Photocatalytic degradation of 2,4-dichlorophenol with MgAlTi mixed oxides catalysts obtained from layered double hydroxides.

MgAl and MgAlTi mixed oxides were obtained from the thermal treatment of LDH materials synthesized by the sol-gel method; these materials were characterized by N2 physisorption, XRD, UV-vis, XPS, EDS-SEM and TEM techniques. According to the results, Ti was incorporated in the LDH layer when content in the material was low. The MgAl and MgAlTi mixed oxides were evaluated in the photo-degradation of 2,4-dichlorophenol (2,4-DCP) in the presence of UV light. A superior efficiency in the photo-degradation of 2,4-DCP, in comparison with the Degussa P-25 TiO2 reference catalyst was observed, reaching a total decomposition of the 2,4-DCP molecule in less than 60 min. According to the results, Ti was incorporated in the LDH layer when the content in the material was low. The MgAl and MgAlTi mixed oxides were evaluated in the photo-degradation of 2,4-dichlorophenol (2,4-DCP) in the presence of UV light. A superior efficiency in the photo-degradation of 2,4-DCP with the MgAl and MgAlTi mixed oxides, in comparison with the Degussa P-25 TiO2 reference catalyst was observed, reaching a total decomposition of the 2,4-DCP molecule in less than 60 min.

Electrochemical properties of Sn-substituted LiMn2O4 thin films prepared by radio-frequency magnetron sputtering.

The LiMn2O4 and LiSn0.0125Mn1975O4 thin films were grown on Pt/Ti/SiO2/Si (100) substrate by RF magnetron sputtering. To obtain the structural stability and good cycle performance, deposition parameters, namely working pressure, sputtering gas ratio of Ar and O2, post-annealing temperature were established. The structure and surface morphology of thin films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrochemical properties were estimated by two electrode half-cell test with WBCS 3000 (Wonatech, Korea) at constant current rate of 1 C-rate. The Sn substituted LiMn2O4 thin film deposited at 10 mtorr with mixture of argon and oxygen (Ar/O2 = 3/1) and then annealed at 500 degrees C in O2 atmosphere showed good cycle performance. The Sn substituted LiMn2O4 thin films showed larger capacity of -30 microAh/microm-cm2 and higher cyclability than LiMn2O4 thin films.

Enhanced emission of Mn2+ via Ce3+ → Mn2+ energy transfer in α-Sr2P2O7.

Mn(2+) doped and Ce(3+)-Mn(2+) co-doped α-Sr(2)P(2)O(7) phosphors were prepared by a traditional high-temperature solid-state reaction route. The UV-vis excitation and emission spectra for all samples were investigated. Luminescence of Mn(2+) is assigned to from two different sites, which is similar to that of Ce(3+). Energy transfer from Ce(3+) to Mn(2+) in co-doped phosphors α-Sr(2)P(2)O(7): 0.03Ce(3+), xMn(2+) and α-Sr(2)P(2)O(7): xCe(3+), 0.1Mn(2+) was investigated by the excitation and emission spectra as well as the luminescence decays. Both Ce(3+)(1) and Ce(3+)(2) can transfer energy to two types of Mn(2+) ions.

Ferromagnetic GaAs structures with single Mn delta-layer fabricated using laser deposition.

The new technique combining metal-organic chemical vapor epitaxy with laser ablation of solid targets was used for fabrication of ferromagnetic GaAs structures with single Mn delta-doped layer. The structures demonstrated anomalous Hall effect, planar Hall effect, negative and anisotropic magnetoresistance in temperature range of 10-35 K. In GaAs structures with only single Mn delta-layer (without additional 2D hole gas channel or quantum well) ferromagnetism was observed for the first time.

Polyacrylonitrile/manganese acetate composite nanofibers and their catalysis performance on chromium (VI) reduction by oxalic acid.

Polyacrylonitrile(PAN)/manganese acetate(Mn(CH(3)COO)(2)) composite nanofibers have been fabricated by electrospinning, a simple and effective technology. The obtained composite nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectrometer (FT-IR). The composite nanofibers are amorphous in structure, continuous, even and smooth. At the same time, the reduction performance of Cr(VI) by oxalic acid in the presence of the composite nanofibers is also investigated. The results indicate that the composite nanofibers have exhibited excellent catalysis performance for Cr(VI) reduction from a Cr(2)O(7)(2-)-containing solution by oxalic acid. And the critical parameters, such as the catalyst dosage, oxalic acid content, chromium concentration, the pH value of the reaction solution and light have important impact on the reduction process. Under the simulated solar light irradiation, after only 60 min, 1.2mM initial Cr(VI) solution was reduced absolutely in the presence of PAN/Mn(CH(3)COO)(2) composite nanofibers containing 17.5 wt.% Mn(CH(3)COO)(2) by 0.3 mL 0.5M oxalic acid. In light, the reduction of Cr(VI) by oxalic acid is markedly accelerated.