A study of older adults: Observation of ranges of life satisfaction and functioning

Levels of daily functioning and life satisfaction in older people are investigated in this study. Surveys and interviews included 425 people aged 65+ and comparisons were made between three age groups (ages 65-74, 75-84, 85 +) on levels of activity, independence and social support; satisfaction with levels of independence, activity and social support and overall life satisfaction, Results indicated that those aged 85+ had significantly lower levels of activity and independence than those in the two younger age groups. Differences were found in 8 of 12 domains of independence and in outdoor work and mobility activities. The oldest age group was also found to be significantly less satisfied with their levels of independence and activity than were the younger age groups. No significant differences were found between the groups in overall life satisfaction. Levels of activity and independence, satisfaction with social support and satisfaction with independence were found to make unique contributions to t to the prediction of variance in overall life satisfaction. Findings are important in understanding what to expect of ourselves and others as we age, which daily activities are likely to be most difficult for older people and what factors are predictors of overall life satisfaction.FALSEPublishe

Magnetic Nanoparticle Composites: Synergistic Effects and Applications

Composite materials are made from two or more constituent materials with distinct physical or chemical properties that, when combined, produce a material with characteristics which are at least to some degree different from its individual components. Nanocomposite materials are composed of different materials of which at least one has nanoscale dimensions. Common types of nanocomposites consist of a combination of two different elements, with a nanoparticle that is linked to, or surrounded by, another organic or inorganic material, for example in a core-shell or heterostructure configuration. A general family of nanoparticle composites concerns the coating of a nanoscale material by a polymer, SiO2 or carbon. Other materials, such as graphene or graphene oxide (GO), are used as supports forming composites when nanoscale materials are deposited onto them. In this Review we focus on magnetic nanocomposites, describing their synthetic methods, physical properties and applications. Several types of nanocomposites are presented, according to their composition, morphology or surface functionalization. Their applications are largely due to the synergistic effects that appear thanks to the co-existence of two different materials and to their interface, resulting in properties often better than those of their single-phase components. Applications discussed concern magnetically separable catalysts, water treatment, diagnostics-sensing and biomedicine

Stable Iron Oxide Nanoflowers with Exceptional Magnetic Heating Efficiency: Simple and Fast Polyol Synthesis

Magnetically induced hyperthermia has reached a milestone in medical nanoscience and in phase III clinical trials for cancer treatment. As it relies on the heat generated by magnetic nanoparticles (NPs) when exposed to an external alternating magnetic field, the heating ability of these NPs is of paramount importance, so is their synthesis. We present a simple and fast method to produce iron oxide nanostructures with excellent heating ability that are colloidally stable in water. A polyol process yielded biocompatible single core nanoparticles and nanoflowers. The effect of parameters such as the precursor concentration, polyol molecular weight as well as reaction time was studied, aiming to produce NPs with the highest possible heating rates. Polyacrylic acid facilitated the formation of excellent nanoheating agents iron oxide nanoflowers (IONFs) within 30 min. The progressive increase of the size of the NFs through applying a seeded growth approach resulted in outstanding enhancement of their heating efficiency with intrinsic loss parameter up to 8.49 nH m2 kgFe-1. The colloidal stability of the NFs was maintained when transferring to an aqueous solution via a simple ligand exchange protocol, replacing polyol ligands with biocompatible sodium tripolyphosphate to secure the IONPs long-term colloidal stabilization

Small iron oxide nanoparticles as MRI T1 contrast agent: scalable inexpensive water-based synthesis using a flow reactor

Small iron oxide nanoparticles (IONPs) were synthesised in water via co-precipitation by quenching particle growth after the desired magnetic iron oxide phase formed. This was achieved in a millifluidic multistage flow reactor by precisely timed addition of an acidic solution. IONPs (≤5 nm), a suitable size for positive T1 magnetic resonance imaging (MRI) contrast agents, were obtained and stabilised continuously. This novel flow chemistry approach facilitates a reproducible and scalable production, which is a crucial paradigm shift to utilise IONPs as contrast agents and replace currently used Gd complexes. Acid addition had to be timed carefully, as the inverse spinel structure formed within seconds after initiating the co-precipitation. Late quenching allowed IONPs to grow larger than 5 nm, whereas premature acid addition yielded undesired oxide phases. Use of a flow reactor was not only essential for scalability, but also to synthesise monodisperse and non-agglomerated small IONPs as (i) co-precipitation and acid addition occurred at homogenous environment due to accurate temperature control and rapid mixing and (ii) quenching of particle growth was possible at the optimum time, i.e., a few seconds after initiating co-precipitation. In addition to the timing of growth quenching, the effect of temperature and dextran present during co-precipitation on the final particle size was investigated. This approach differs from small IONP syntheses in batch utilising either growth inhibitors (which likely leads to impurities) or high temperature methods in organic solvents. Furthermore, this continuous synthesis enables the low-cost (<£10 per g) and large-scale production of highly stable small IONPs without the use of toxic reagents. The flow-synthesised small IONPs showed high T1 contrast enhancement, with transversal relaxivity (r2) reduced to 20.5 mM−1 s−1 and longitudinal relaxivity (r1) higher than 10 mM−1 s−1, which is among the highest values reported for water-based IONP synthesis

Shape controlled iron oxide nanoparticles: inducing branching and controlling particle crystallinity

Anisotropic nanoparticles (NPs) have garnered a great deal of attention for their applications in catalysis, magnetism and biomedicine. However, synthetic strategies to grow such NPs are still limited as their growth mechanisms are poorly understood. This work presents the synthesis of iron oxide nanoparticles (IONPs) based on the decomposition of iron(III) acetylacetonate in organic solvents to form anisotropic IONPs that are branched or multiply branched. We fully explore their growth parameters to understand the effect of varying amounts of oleylamine (OAm), as well as a nitrogen purge on particle morphology. We show here the synthetic relationship between a wide range of sizes and shapes of IONPs that are both isotropic and anisotropic. Of all the parameters, the amount of oleylamine in the reaction is the key to tune the particle size while the effect of a nitrogen gas purge during synthesis was shown to be crucial for the formation of the branched and multiply branched NPs. Two multiply branched NP systems with only a small difference in the synthetic conditions were shown to have radically different magnetic properties, such as heating in an alternating magnetic field. This was attributed to the defects found in the structure of one and not in the other. By following their development during growth, crystal defects were observed in both systems during the early stages of the reaction. However, for the multiply branched structure that became single crystalline, the aggregation of the nuclei occurred earlier in the reaction, allowing more time for growth and crystallite rearrangement to occur. These results have wide ranging implications for controlling the properties of anisotropic nanomaterials with similar structures, including their magnetic behavior

Environmental STEM Study of the Oxidation Mechanism for Iron and Iron Carbide Nanoparticles

The oxidation of solution-synthesized iron (Fe) and iron carbide (Fe2C) nanoparticles was studied in an environmental scanning transmission electron microscope (ESTEM) at elevated temperatures under oxygen gas. The nanoparticles studied had a native oxide shell present, that formed after synthesis, an ~3 nm iron oxide (FexOy) shell for the Fe nanoparticles and ~2 nm for the Fe2C nanoparticles, with small void areas seen in several places between the core and shell for the Fe and an ~0.8 nm space between the core and shell for the Fe2C. The iron nanoparticles oxidized asymmetrically, with voids on the borders between the Fe core and FexOy shell increasing in size until the void coalesced, and finally the Fe core disappeared. In comparison, the oxidation of the Fe2C progressed symmetrically, with the core shrinking in the center and the outer oxide shell growing until the iron carbide had fully disappeared. Small bridges of iron oxide formed during oxidation, indicating that the Fe transitioned to the oxide shell surface across the channels, while leaving the carbon behind in the hollow core. The carbon in the carbide is hypothesized to suppress the formation of larger crystallites of iron oxide during oxidation, and alter the diffusion rates of the Fe and O during the reaction, which explains the lower sensitivity to oxidation of the Fe2C nanoparticles

Synthesis of Fine-Tuning Highly Magnetic Fe@FexOy Nanoparticles through Continuous Injection and a Study of Magnetic Hyperthermia

Core@shell Fe@FexOy nanoparticles (NPs) have the potential to be promising tools for many applications, thanks to their combination of an iron core, with a high magnetic moment and an iron oxide shell which could protect the core from oxidation. However, the deterioration of NPs structure can lead to the shrinking of the core and the hollowing of the structure, diminishing the magnetic properties. The ability to retain the iron core under biomedically compatible conditions is desirable for many applications. In this paper, we have developed a synthetic method to produce core@shell α-Fe@FexOy NPs with tunable sizes and evaluated the retention of the stable magnetic α-Fe core upon exposure to air and after ligand exchange and its resulting effect on the magnetic hyperthermia. In particular, using a continuous injection of the precursor, we were able to finely tune the final size of the core@shell NPs producing four samples with average sizes of 12, 15, 18, and 20 nm. The structural properties of the particles were studied, and while the size increases, the chemical stability of the iron core is enhanced, and the magnetic properties improved accordingly. Particles larger than 20 nm were shown to be prone to aggregation, resulting in an abrupt increase of the particle size distribution. Two samples with high magnetization saturation value and low polydispersity, 15 and 18 nm, were transferred in water using a dopamine-functionalized poly(isobutylene-alt-maleic anhydride) polymer, resulting in colloidal stability over a wide range of pH and ionic strength comparable to physiological conditions. We found that the 18 nm particles retain their chemical properties over 2 months, with less oxidation of the Fe core; this results in a specific absorption rate (SAR) value of 660 W g−1 and intrinsic loss power (ILP) of 3.6 nHm2 kg−1 , while the 15 nm NPs resulted in the reduction of their properties due to oxidation of the core

Room-temperature emitters in wafer-scale few-layer hBN by atmospheric pressure CVD

Hexagonal boron nitride (hBN) is a two-dimensional, wide band gap semiconductor material suitable for several technologies. 2D hBN appeared as a viable platform to produce bright and optically stable single photon emitters (SPEs) at room temperature, which are in demand for quantum technologies. In this context, one main challenge concerns the upscaling of 2D hBN with uniform spatial and spectral distribution of SPE sources. In this work we optimized the atmospheric-pressure chemical vapor deposition (APCVD) growth and obtained large-area 2D hBN with uniform fluorescence emission properties. We characterized the hBN films by a combination of electron microscopy, Raman and X-ray photoelectron spectroscopy techniques. The extensive characterization revealed few-layer, polycrystalline hBN films (∼3 nm thickness) with balanced stoichiometry and uniformity over 2″ wafer scale. We studied the fluorescence emission properties of the hBN films by multidimensional hyperspectral fluorescence microscopy. We measured simultaneously the spatial position, intensity, and spectral properties of the emitters, which were exposed to continuous illumination over minutes. Three main emission peaks (at 538, 582, and 617 nm) were observed, with associated replica peaks red-shifted by ∼53 nm. A surface emitter density of ∼0.1 emitters/μm2 was found. A comparative test with pristine hBN nanosheets produced by liquid-phase exfoliation (LPE) was performed, finding that CVD and LPE hBN possess analogous spectral emitter categories in terms of peak position/intensity and density. Overall, the line-shape and wavelength of the emission peaks, as well as the other measured features, are consistent with single-photon emission from hBN. The results indicate that APCVD hBN might proficiently serve as a SPE platform for quantum technologies.We acknowledge the financial support of i) the project “GEMIS – Graphene-enhanced Electro Magnetic Interference Shielding,” with the reference POCI-01-0247-FEDER-045939, co-funded by COMPETE 2020 – Operational Programme for Competitiveness and Internationalization and FCT –Science and Technology Foundation, under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); ii) the project "Graphene and novel thin films for super-resolution microscopy and bio-sensing" (PTDC/NAN-OPT/29417/2017) financed by ERDF, through the Competitiveness and Internationalization Operational Program (POCI) by Portugal 2020 and by the Portuguese Foundation for Science and Technology (FCT) with references POCI-01-0145-FEDER-029417 and PTDC/NAN-OPT/29417/2017; iii) the FCT in the framework of the Strategic Funding UIDB/04650/2020. One of the authors (T.Q.) acknowledges the FCT financial support under the Quantum Portugal Initiative Ph.D. scholarship SFRH/BD/150646/2020. We acknowledge the support by the INL AEMIS, Micro- and Nanofabrication, and Nanophotonics and Bioimaging research core facilities

Co-precipitation synthesis of stable iron oxide nanoparticles with NaOH: New insights and continuous production via flow chemistry

Co-precipitation is by far the most common synthesis for magnetic iron oxide nanoparticles (IONPs), as cheap and environmentally friendly precursors and simple experimental procedures facilitate IONP production in many labs. Optimising co-precipitation syntheses remains challenging however, as particle formation mechanisms are not well understood. This is partly due to the rapid particle formation (within seconds) providing insufficient time to characterise initial precipitates. To overcome this limitation, a flow chemistry approach has been developed using steady-state operation to “freeze” transient reaction states locally. This allowed for the first time a comprehensive analysis of the early stages of co-precipitation syntheses via in-situ Small Angle X-ray Scattering and in-situ synchrotron X-Ray Diffraction. These studies revealed that after mixing the ferrous/ferric chloride precursor with the NaOH base solution, the most magnetic iron oxide phase forms within 5 s, the particle size changes only marginally afterwards, and co-precipitation and agglomeration occur simultaneously. As these agglomerates were too large to achieve colloidal stability via subsequent stabiliser addition, co-precipitated IONPs had to be de-agglomerated. This was achieved by adding the appropriate quantity of a citric acid solution which yielded within minutes colloidally stable IONP solutions around a neutral pH value. The new insights into the particle formation and the novel stabilisation procedure (not requiring any ultra-sonication or washing step) allowed to design a multistage flow reactor to synthesise and stabilise IONPs continuously with a residence time of less than 5 min. This reactor was robust against fouling and produced stable IONP solutions (of ~1.5 mg particles per ml) reproducibly via fast mixing ( 500 ml/h) for low materials cost

Zn doped iron oxide nanoparticles with high magnetization and photothermal efficiency for cancer treatment

Magnetic nanoparticles (NPs) are powerful agents to induce hyperthermia in tumours upon the application of an alternating magnetic field or an infrared laser. Dopants have been investigated to alter different properties of materials. Herein, the effect of zinc doping into iron oxide NPs on their magnetic properties and structural characteristics has been investigated in-depth. A high temperature reaction with autogenous pressure was used to prepare iron oxide and zinc ferrite NPs of same size and morphology for direct comparison. Pressure was key in obtaining high quality nanocrystals with reduced lattice strain (27% less) and enhanced magnetic properties. Zn_{0.4}Fe_{2.6}O_{4} NPs. with small size of 10.2 ± 2.5 nm and very high saturation magnetisation of 142 ± 9 emu g_{Fe+Zn}^{−1} were obtained. Aqueous dispersion of the NPs showed long term magnetic (up to 24 months) and colloidal stability (at least 6 d) at physiologically mimicking conditions. The samples had been kept in the fridge and had been stable for four years. The biocompatibility of Zn_{0.4}Fe_{2.6}O_{4} NPs was next evaluated by metabolic activity, membrane integrity and clonogenic assays, which show an equivalence to that of iron oxide NPs. Zinc doping decreased the bandgap of the material by 22% making it a more efficient photothermal agent than iron oxide-based ones. Semiconductor photo-hyperthermia was shown to outperform magneto-hyperthermia in cancer cells, reaching the same temperature 17 times faster whilst using 20 times less material (20 mg_{Fe+Zn} ml^{−1}vs. 1 mg_{Fe+Zn} ml^{−1}). Magnetothermal conversion was minimally hindered in the cellular confinement whilst photothermal efficiency remained unchanged. Photothermia treatment alone achieved 100% cell death after 10 min of treatment compared to only 30% cell death achieved with magnetothermia at clinically relevant settings for each at their best performing concentration. Altogether, these results suggest that the biocompatible and superparamagnetic zinc ferrite NPs could be a next biomaterial of choice for photo-hyperthermia, which could outperform current iron oxide NPs for magnetic hyperthermia