Finite size effects on the metamagnetic phase transition in a thick B2 FeRh nanocluster film.

FeRh alloys in the CsCl-type (B2) chemically ordered phase present an antiferromagnetic to ferromagnetic order transition around 370 K observed in bulk and continuous films but absent in nanoclusters. In this study, we investigate the thermal magnetic behavior of a thick film composed of assembled FeRh nanoclusters preformed in the gas phase. This work reveals a broad and asymmetric metamagnetic transition with a consequent residual magnetization at low temperature. Due to the coexistence of different grain sizes in the sample, we confront the results with a description that involves two populations of B2-FeRh particles, and the existence of a discriminating size below which the magnetic order transition does not take place.

Masticatory coefficient and physical functioning in older frail patients admitted for a Comprehensive Gerontological Assessment.

BACKGROUND: Physical functioning may be limited in older, frail patients with missing teeth without prosthetic correction. This cross-sectional study examined the relationship between physical performance and the geriatric masticatory coefficient (GMC) in patients who underwent both a comprehensive gerontological assessment (CGA) to improve poly-pathology management and an intra-oral exam. METHODS: All patients were evaluated based on the following: (corrected) GMC, number of posterior occluding pairs (POPs), short physical performance battery (SPPB) or timed up and go (TUG) test, and mini-nutritional assessment (MNA). RESULTS: Of the 256 patients (mean age 83.76[SD 6.16], 148F), 75 (29.30%) were malnourished. The corrected GMC was lower in malnourished patients. When adjusted for age, gender, and MNA, the corrected GMC correlated with the TUG time (r=-0.198, p=0.005) and SPPB score (r=0.282, p=0.009). Correlations between GMC and POPs were determined for the SPPB (r=0.269, p=0.013; r=0.319, p=0.004, respectively) but not for the TUG (r=-0.108, p=0.128; r=-0.136, p=0.072). CONCLUSION: The correlation between physical performance and decreased masticatory capacity was not fully explained by malnutrition in mildly to severely frail and multi-morbid patients; posture may also be impaired by missing teeth. The study of dental care effects on physical performance will provide further insights.

Elaboration of Nanomagnet Arrays: Organization and Magnetic Properties of Mass-Selected FePt Nanoparticles Deposited on Epitaxially Grown Graphene on Ir(111).

The moiré pattern created by the epitaxy of a graphene sheet on an iridium substrate can be used as a template for the growth of 2D atomic or cluster arrays. We observed for the first time a coherent organization of hard magnetic preformed FePt nanoparticles on the 2D lattice of graphene on Ir(111). Nanoparticles of 2 nm diameter have been mass selected in a gas phase and deposited with low energy on the hexagonal moiré pattern. Their morphology and organization have been investigated using grazing incidence small angle x-ray scattering, while their magnetic properties have been studied by x-ray magnetic circular dichroism, both pointing to a FePt cluster-graphene surface specific interaction. The spatial coherence of the nanoparticles is preserved upon annealing up to 700 °C where the hard magnetic phase of FePt is obtained.

Prevention of tooth loss and dental pain for reducing the global burden of oral diseases.

Population ageing is a global phenomenon and is predicted to become one of the most significant social transformations of the 21st century. The anticipated demographic shift provides governments the opportunity to proactively align policies with the estimated demands for housing, transportation, social protection, and health and well-being. Oral health is a fundamental component of health and physical and mental well-being, and is influenced by the individual's changing experience, perceptions, expectations and ability to adapt to circumstances. As such, prevention of oral disease and maintenance of oral health contributes to the systemic health, well-being, and quality of life of older adults. Dental caries, periodontal disease, and tooth loss in older adults are global health concerns because they are highly prevalent worldwide, socio-economic inequalities contribute to these diseases, many of the risk factors are modifiable, and these diseases result in compromised oral health-related quality of life. Oral care must be tailored to the needs and level of dependency of older adults through the use of evidence-based approaches and inter-professional collaboration. The persistence of between countries and within countries oral health disparities indicate that population-based policies are also needed to address the underlying social, environmental, and economic causes of oral diseases.

Progressive freezing of interacting spins in isolated finite magnetic ensembles.

Self-organization of magnetic nanoparticles into secondary nanostructures provides an innovative way for designing functional nanomaterials with novel properties, different from the constituent primary nanoparticles as well as their bulk counterparts. Collective magnetic properties of such complex closed packing of magnetic nanoparticles makes them more appealing than the individual magnetic nanoparticles in many technological applications. This work reports the collective magnetic behaviour of magnetic ensembles comprising of single domain Fe3O4 nanoparticles. The present work reveals that the ensemble formation is based on the re-orientation and attachment of the nanoparticles in an iso-oriented fashion at the mesoscale regime. Comprehensive dc magnetic measurements show the prevalence of strong interparticle interactions in the ensembles. Due to the close range organization of primary Fe3O4 nanoparticles in the ensemble, the spins of the individual nanoparticles interact through dipolar interactions as realized from remnant magnetization measurements. Signature of super spin glass like behaviour in the ensembles is observed in the memory studies carried out in field cooled conditions. Progressive freezing of spins in the ensembles is corroborated from the Vogel-Fulcher fit of the susceptibility data. Dynamic scaling of relaxation reasserted slow spin dynamics substantiating cluster spin glass like behaviour in the ensembles.

Cubic chemically ordered FeRh and FeCo nanomagnets prepared by mass-selected low-energy cluster-beam deposition: a comparative study.

Near the point of equiatomic composition, both FeRh and FeCo bulk alloys exhibit a CsCl-type (B2) chemically ordered phase that is related to specific magnetic properties, namely a metamagnetic anti-ferromagnetic/ferromagnetic transition near room temperature for FeRh and a huge magnetic moment for the FeCo soft alloy. In this paper, we present the magnetic and structural properties of nanoparticles of less than 5 nm diameter embedded in an inert carbon matrix prepared by mass-selected low-energy cluster-beam deposition technique. We obtained a CsCl-type (B2) chemically ordered phase for annealed nanoalloys. Using different experimental measurements, we show how decreasing the size affects the magnetic properties. FeRh nanoparticles keep the ferromagnetic order at low temperature due to surface relaxation affecting the cell parameter. In the case of FeCo clusters, the environment drastically affects the intrinsic properties of this system by reducing the magnetization in comparison to the bulk.

Relationships between oral health, dysphagia and undernutrition in hospitalised elderly patients.

OBJECTIVE: The aim of this study was to describe relationships between oral status, dysphagia and malnutrition in a hospitalised older people. BACKGROUND: Undernutrition in older people is a major concern in geriatric hospital wards. Different factors can modify nutritional status like dysphagia or oral status. MATERIALS AND METHODS: About 159 consecutive inpatients (108 women, 51 men) were examined. Comprehensive gerontological data at baseline and nutritional status according to BMI, MNA and serum albumin concentration, dependency according to ADL scores, dietary intake, swallowing capacities and oral status were collected. Swallowing capacities and dietary intake were reassessed 1 week after. RESULTS: Mean age was 85.28 (SD 5.68). Seventy-seven patients were malnourished (MNA) and 34 had dysphagia. Oral treatment was necessary in 142 patients (89.30% of all population). Candidiasis was present in 17 patients and salivary flow reduction in 50. Patients with dysphagia had the lowest dietary intake. After 1 week, patients with dysphagia were retested and dysphagia had abated in three of them. Dysphagia and undernutrition were associated (p < 0.001), and both were related to candidiasis (p < 0.001 and p < 0.01). Dysphagia was also related to salivary hypofunction (p < 0.001), loss of posterior occluding pairs (POPs; p = 0.014), oral self-care dependency (p < 0.001) and self-feeding dependency (p < 0.001). Salivary hypofunction was related to candidiasis (p < 0.001) and loss of POPs (p < 0.05), and candidiasis to loss of POPs (p < 0.01). CONCLUSION: Although no causality can be demonstrated, poor oral health was strongly associated with malnutrition, emphasising the importance to develop oral care strategies and to incorporate a dental examination into comprehensive gerontological assessment.

Size effects in the magnetic anisotropy of embedded cobalt nanoparticles: from shape to surface.

Strong size-dependent variations of the magnetic anisotropy of embedded cobalt clusters are evidenced quantitatively by combining magnetic experiments and advanced data treatment. The obtained values are discussed in the frame of two theoretical models that demonstrate the decisive role of the shape in larger nanoparticles and the predominant role of the surface anisotropy in clusters below 3 nm diameter.

Efficiency at the resident's level of the NABUCCOD nutrition and oral health care training program in nursing homes.

OBJECTIVES: To assess the impact of a nutrition and oral care training program on nursing home (NH) policies and residents. DESIGN: Cross-sectional surveys before/after intervention. PARTICIPANTS: One hundred thirty-eight NHs participated in the initial training. INTERVENTION: Training sessions for staff, director, and medical practitioners for nutritional and oral care in NH. MEASUREMENTS: Two waves of self-assessments over a 6- to 8-month interval described NH policies (Institution questionnaire), quality of care in newly admitted residents (Admission questionnaire), and in those present for more than 6 months (Stay questionnaire). RESULTS: Questionnaires were completed at both waves in 24 NHs (17.8%) for Institution, in 42 NHs including 646 residents for Admission, and in 34 NHs including 287 residents for Stay. There was no significant difference in bed capacity and resident dependency between NHs, which performed both assessments, and nonresponders. No change was observed for Institution. Malnutrition screening was carried out in almost all residents. Two risk factors were better screened after training: pressure ulcers (39.4% to 49.1%, P = .014) and dysphagia (33.5% to 41.0%, P = .049). Oral examination improved quantitatively (38.5% of residents to 48.5%) and qualitatively: risk factors for malnutrition and dysphagia were better sought (loss of posterior teeth (P < .0001), asialia (P < .0001), and candidosis (P = .002)). Similar improvements were seen in Stay assessments. Actions to counteract weight loss or low dietary intake records were not found in one third of resident records. CONCLUSIONS: Training program improved staff knowledge with positive results at the level of residents but no significant changes were seen within NH policies.

Nontrivial redox behavior of nanosized cobalt: new insights from ambient pressure X-ray photoelectron and absorption spectroscopies.

The reduction and oxidation of carbon-supported cobalt nanoparticles (3.50±0.22 nm) and a Co (0001) single crystal was investigated by ambient pressure X-ray photoelectron (APPES) and X-ray absorption (XAS) spectroscopies, applied in situ under 0.2 mbar hydrogen or oxygen atmospheres and at temperatures up to 620 K. It was found that cobalt nanoparticles are readily oxidized to a distinct CoO phase, which is significantly more stable to further oxidation or reduction compared to the thick oxide films formed on the Co(0001) crystal. The nontrivial size-dependence of redox behavior is followed by a difference in the electronic structure as suggested by theoretical simulations of the Co L-edge absorption spectra. In particular, contrary to the stable rocksalt and spinel phases that exist in the bulk oxides, cobalt nanoparticles contain a significant portion of metastable wurtzite-type CoO.

When a Metastable Oxide Stabilizes at the Nanoscale: Wurtzite CoO Formation upon Dealloying of PtCo Nanoparticles.

Ambient pressure photoelectron and absorption spectroscopies were applied under 0.2 mbar of O2 and H2 to establish an unequivocal correlation between the surface oxidation state of extended and nanosized PtCo alloys and the gas-phase environment. Fundamental differences in the electronic structure and reactivity of segregated cobalt oxides were associated with surface stabilization of metastable wurtzite-CoO. In addition, the promotion effect of Pt in the reduction of cobalt oxides was pronounced at the nanosized particles but not at the extended foil.