Publications by authors named "Dupuis V"

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.

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Article Synopsis
  • Maghemite nanoparticles modified with Co(II) coordination complexes show enhanced magnetic properties, including doubled blocking temperature and increased coercive field, due to changes in magnetic anisotropy.
  • Magnetometric studies indicate that this enhancement stems from molecular interactions between Co(II) and oxygen atoms at the nanoparticle surface, affecting both surface and core magnetic characteristics.
  • X-ray spectroscopy techniques confirm strong magnetic exchange interactions at room temperature, with similar effects observed in Ni(II) modified nanoparticles, highlighting the role of oxido coordination bridges in magnetic coupling.
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Purpose: Native Americans and Latinos have higher COVID-19 infection and mortality rates and may have limited access to diagnostic testing. Home-based testing may improve access to care in rural and underserved populations. This study tests the effect of community health worker (CHW) support on accessibility, feasibility, and completion of COVID-19 home testing among Native American and Latino adults living on the Flathead Reservation in Montana and in Yakima Valley, Washington.

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Objective: To examine factors influencing decisions to test for COVID-19 among Native Americans on the Flathead Reservation in Montana and the Latino community in the Yakima Valley of Washington state.

Methods: We conducted 30 key informant interviews with community leaders and six focus groups with community members to examine factors impacting decisions to test for COVID-19 during the second year of the COVID-19 pandemic from May 2021 to June 2021.

Results: Three major themes that impacted testing for COVID-19 were identified: (1) Social factors, including the influence of families and friends and employment practices; (2) health factors, including testing procedures, home-based testing, and health communication; and (3) contextual factors, including distrust for government and medical communities and the impact on cultural practices and celebrations.

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Nanoscale heterostructures of covalent intermetallics should give birth to a wide range of interface-driven physical and chemical properties. Such a level of design however remains unattainable for most of these compounds, due to the difficulty to reach a crystalline order of covalent bonds at the moderate temperatures required for colloidal chemistry. Herein, we design heterostructured cobalt silicide nanoparticles to trigger magnetic and catalytic properties in silicon-based materials.

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Background: Mechanisms underlying the associations between changes in the urban environment and changes in health-related outcomes are complex and their study requires specific approaches. We describe the protocol of the interdisciplinary UrbASanté study, which aims to explore how urban interventions can modify environmental exposures (built, social, and food environments; air quality; noise), health-related behaviors, and self-reported health using a natural experiment approach.

Methods: The study is based on a natural experiment design using a before/after protocol with a control group to assess changes in environmental exposures, health-risk behaviors, and self-reported health outcomes of a resident adult population before and after the implementation of a time series of urban interventions in four contiguous neighborhoods in Paris (France).

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Households with a low-income in rural places experience disproportionate levels of food insecurity. Further research is needed about the nuances in strategies that households with a low-income in rural areas apply to support food security nationally. This study aimed to understand the barriers and strategies that households with a low-income in rural areas experience to obtain a meal and support food security in the United States.

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Background: Home-based testing for COVID-19 has potential to reduce existing health care disparities among underserved populations in the United States. However, implementation of home-based tests in these communities may face significant barriers. This study evaluates the acceptability, feasibility, and success of home-based testing and the potential added benefit of active support from trusted community health workers for Native Americans and Hispanic/Latino adults living in rural Montana and Washington states.

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This review provides a synthesis of the last ten years of research on nanodelivery systems used for the delivery of essential oils (EOs), as well as their potential as a viable alternative to antibiotics in human and veterinary therapy. The use of essential oils alone in therapy is not always possible due to several limitations but nanodelivery systems seem to be able to overcome these issues. The choice of the essential oil, as well as the choice of the nanodelivery system influences the therapeutic efficacy obtained.

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Mesenchymal stem cells (MSCs) have received significant attention in recent years due to their large potential for cell therapy. Indeed, they secrete a wide variety of immunomodulatory factors of interest for the treatment of immune-related disorders and inflammatory diseases. MSCs can be extracted from multiple tissues of the human body.

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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).

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Magnetic hyperthermia on core-shell nanoparticles bears promising achievements, especially in biomedical applications. Here, thanks to magnetic hyperthermia, γ-FeO cores are able to release a DNA target mimicking the liver specific oncotarget miRNA-122. Our silica coated magnetic nanoparticles not only allow the grafting at their surface of a significant number of oligonucleotides but are also shown to be as efficient, by local heating, as 95 °C global heating when submitted to an alternative magnetic field, while keeping the solution at 28 °C, crucial for biological media and energy efficiency.

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The heating of a biologic solution is a crucial part in an amplification process such as the catalytic detection of a biological target. However, in many situations, heating must be limited in microfluidic devices, as high temperatures can cause the denaturation of the chip components. Local heating through magnetic hyperthermia on magnetic nano-objects has opened the doors to numerous improvements, such as for oncology where a reduced heating allows the synergy of chemotherapy and thermotherapy.

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Background: Indigenous food systems have been displaced with the emergence of colonization, industrialization, and cultural, economic, political, and environmental changes. This disruption can be seen in marked health and food environment disparities that contribute to high obesity and diabetes mellitus prevalence among Native American peoples.

Methods: A Community-Based Participatory Research (CBPR) approach was used to document food environment experiences among residents of the Flathead Reservation in rural Montana.

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Tribal communities in the United States face disparities to accessing healthy foods including high-quality produce. A six-week fresh fruit and vegetable (FV) dietary intervention, , was co-designed with a Community Advisory Board of local food and nutrition stakeholders on the Flathead Reservation of the Confederated Salish and Kootenai Tribes in Montana. was implemented as a pilot study with low-income participants ( = 19) enrolled in the Food Distribution Program on Indian Reservations toward improving dietary quality and perceptions of well-being.

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Fluids responding to magnetic fields (ferrofluids) offer a scene with no equivalent in nature to explore long-range magnetic dipole interactions. Here, we studied the very original class of binary ferrofluids, embedding soft and hard ferrimagnetic nanoparticles. We used a combination of X-ray magnetic spectroscopy measurements supported by multi-scale experimental techniques and Monte-Carlo simulations to unveil the origin of the emergent macroscopic magnetic properties of the binary mixture.

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Background: Older persons comprise a growing proportion of the European population and may have a distinct epidemiological oral profile requiring specific preventive and curative care poorly documented. The objectives of this study were to assess the oral health status of people ≥90 years of age in France, to compare their perceived and observed oral care needs and to investigate the oral problems associated with a low oral health-related quality-of-life (OHRQoL).

Methods: An oral cross-sectional study was performed during the 25th follow-up of a cohort of older persons being followed up prospectively for screening of dementia over a 15-year period in Gironde and Dordogne, France.

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This case study describes a methodological approach to evaluating and improving food environments in an indigenous community in the United States of America. A community-research partnership was developed to support healthy diets from sustainable food systems. Our team implemented complementary methodologies to evaluate multiple dimensions of the food environment, including food availability, convenience, affordability and desirability.

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Diet-related chronic disease is among the most pressing public health issues and represents a health disparity among Native American communities. A community-based participatory approach was taken to evaluate dietary quality of adult residents of the Flathead Reservation of the Confederated Salish & Kootenai Tribes in Montana (the Flathead Nation). A survey was administered to collect basic demographic information and food security status (N = 80).

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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.

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Article Synopsis
  • Brochard and de Gennes predicted that mixing nematic liquid crystals with ferromagnetic particles could lower the critical magnetic field required for the Fredericksz transition, but this effect is seldom observed due to surface anchoring effects.
  • In an optical and light scattering study of the liquid crystal pentylcyanobiphenyl (5CB) doped with 6 nm nanoparticles, researchers discovered a significant reduction in the Fredericksz threshold at low nanoparticle concentrations, attributed to a coating effect from polydimethylsiloxane copolymer chains.
  • The threshold exhibited complex behavior with concentration changes, initially decreasing by 23-31% before rising again, indicating that isolated nanoparticles are more effective than aggregates at influencing the threshold.
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Amino-functionalized core-shell magnetic nanoparticles have been covalently grafted with Polyoxometalates (POMs). These multifunctional nanocomposites have been obtained through the coupling of heteropolytungstate-based hybrids bearing carboxylic acid functions with aminopropyl functions that decorate the core-shell nanoparticles. The physical properties of the resulting materials have been studied by a large set of techniques.

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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.

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  • The study demonstrates that using oriented arrays of smectic A defects, termed smectic oily streaks, can effectively orient gold nanorods (GNRs) across a range of sizes and ligands.
  • It was found that increasing the density of small GNRs led to the formation of oriented end-to-end chains, revealing their alignment predominantly along the oily streaks.
  • The research also highlights the electromagnetic coupling of the GNRs, showing that their orientation influences their luminescence and interaction, which is further affected by van der Waals forces and steric repulsion between them.
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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.

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