Abstract The core and surface structure, and magnetism of mechano-synthesized LaFeO 3 nanoparticles (30–40 nm), Eu 3+ -doped (La 0.70 Eu 0.30 FeO 3 ), and Eu 3+ /Cr 3+ co-doped (La 0.70 Eu 0.30 Fe ...0.95 Cr 0.05 O 3 ) are reported. Doping results in a transition from the O ′ -type to the O-type distorted structure. Traces of reactants, intermediate phases, and a small amount of Eu 2+ ions were detected on the surfaces of the nanoparticles. The nanoparticles consist of antiferromagnetic cores flanked by ferromagnetic shells. The Eu 3+ dopant ions enhance the magnetization values relative to those of the pristine nanoparticles and result in magnetic susceptibilities compatible with the presence of Eu 3+ van Vleck paramagnetism of spin–orbit coupling constant (λ = 363 cm −1 ) and a low temperature Curie–Weiss like behavior associated with the minority Eu 2+ ions. Anomalous temperature-dependent magnetic hardening due to competing magnetic anisotropy and magnetoelectric coupling effects together with a temperature-dependent dopant-sensitive exchange bias, caused by thermally activated spin reversals at the core of the nanoparticles, were observed.
A recent report found that rare predicted loss-of-function (pLOF) variants across 13 candidate genes in TLR3- and IRF-7 dependent type I IFN pathways explain up to 3.5% of severe COVID-19 cases. We ...performed whole-exome or whole genome sequencing of 1,864 COVID-19 cases (713 with severe and 1,151 with mild disease) and 15,033 ancestry- matched population controls across 4 independent COVID-19 biobanks. We tested whether rare pLOF variants in these 13 genes were associated with severe COVID-19. We identified only 1 rare pLOF mutation across these genes among 713 cases with severe COVID-19 and observed no enrichment of pLOFs in severe cases compared to population controls or mild COVID-19 cases. We found no evidence of association of rare LOF variants in the 13 candidate genes with severe COVID-19 outcomes.
The magnetocaloric effect in an array of nanocomposites manganite Nd1-xSrxMnO3 (x = 0.0, 0.2, 0.4, 0.6 and 0.8) was reported in this study. The nanocomposites were synthesized using auto-combustion ...sol-gel technique where replacing Nd3+ by Sr2+ influence the structure and hence enhancing the magnetic properties and magnetocaloric effect. The synthesized nanocomposites form an orthorhombic crystal structure with Pnma space group No.62 and the average crystallite size was found to be ∼30 nm. The tunning (Mn4+/Mn3+) ratio varies in the nanocomposites with different concentration where the Nd0.6Sr0.4MnO3 nanocomposite exhibits maximum (Mn4+/Mn3+) ratio. The ZFC-FC magnetization measurements indicate that all samples exhibit ferromagnetic (FM) to paramagnetic (PM) transition with increasing temperature and other phase transitions are observed for all samples except Nd0.6Sr0.4MnO3 which also shows a peak Curie temperature (TC = 256 K) in the vicinity of room temperature. The presence of FM in NdMnO3 sample is highly enhanced via FM double exchange (DE) interaction due to self-doping process. Room temperature hysteresis loop reveals paramagnetic (PM) behaviour whereas the pronounced effect presents in Nd0.6Sr0.4MnO3 compound compared to other compounds. However, all compounds exhibit FM behaviour at low temperature measurements with saturation magnetization (Ms) raising up gradually and reaching its maximum at x = 0.4. The magnetic entropy change | ΔSM | is calculated through isotherms measurements and Nd0.6Sr0.4MnO3 nanocomposite exhibits a relatively giant value of magnetic entropy (12.71 J/kg.K and 7.78 J/kg.K at around 257.5 K) under a maximum applied magnetic field of 9 T and 5 T respectively. The corresponding relative cooling power (RCP) for this compound is found accordingly as 636.9 J/kg and 349.8 J/kg. The obtained results in the wide range of temperature starting from very low temperature up to room temperature recommend Nd0.6Sr0.4MnO3 compound as a good potential material for magnetic cooling.
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•The interaction between DE and SE by following the development of Mn4+/Mn3+ ratio in Nd1-xSrxMnO3 (0.0, 0.2, 0.4, 0.6 and 0.8) nanocomposites has been presented.•The magnetocaloric MC parameters over the wide range of temperature showed the giant magnetocaloric effect with high relative cooling power in Nd0.6Sr0.4MnO3 compound.•The magnetic properties as well as magnetocaloric (MC) effect and the relative cooling power (RCP) results of Nd0.8Sr0.2MnO3 and NdMnO3 compounds are promising for more study to select the suitable materials for magnetic refrigeration.
Visible light photocatalytic activity of the plasmonic gold–zinc oxide (Au–ZnO) nanorods (NRs) is investigated with respect to the surface defects of the ZnO NRs, controlled by annealing the NRs in ...ambient at different temperatures. Understanding the role of surface defects on the charge transfer behaviour across a metal–semiconductor junction is vital for efficient visible light active photocatalysis. Au nanoparticles (NPs) are in situ deposited on the surface of the ZnO NRs having different surface defect densities, demonstrating efficient harvesting of visible light due to the surface plasmon absorption. The surface defects in the ZnO NRs are probed by using photoluminescence (PL) spectroscopy, X-ray photoemission spectroscopy (XPS), and photo-electro-chemical current–voltage measurements to study the photo-generated charge transfer efficiency across the Au–ZnO Schottky interface. The results show that the surface situated oxygen vacancy sites in the ZnO NRs significantly reduce the charge transfer efficiency across the Au–ZnO Schottky interfaces lowering the photocatalytic activity of the system. Reduction in the oxygen vacancy sites through annealing the ZnO NRs resulted in the enhancement of visible light enabled photocatalytic activity of the Au–ZnO plasmonic nanocatalyst, adding vital insight towards the design of efficient plasmonic photocatalysts.
A thin layer of gold nanoparticles (AuNPs) was deposited on glass substrates followed by subsequent deposition of silver nanoparticles (AgNPs) on it. Both AuNPs and AgNPs layers were fabricated by DC ...magnetron sputtering with inert gas condensation technique. The effect of initial thin layer of AuNPs have on the transformation of AgNPs surface structure by post annealing at 500 °C and 600 °C in air was investigated. The influence of post annealing temperature on the surface morphology was studied by atomic force microscopy and post annealing at 500 °C reduce the size of AgNPs along with the formation of some AgNPs inside the glass matrix. At 600 °C, aggregation of AuNPs on the surface was observed and increased in the number of AgNPs that diffused into the glass matrix. X-ray photoelectron spectroscopy was employed to study the surface composition and chemical states. The temperature dependence of Ag diffusion into the glass matrix was characterised and observed by UV–visible absorption spectroscopy and cross sectional transmission electron microscopy. Furthermore, ultraviolet photoelectron spectroscopy revealed a new shoulder related to Au 6 s hybridized with Au 5d and Ag 4d bands in the 1–4 eV regions, which affirmed the metallic character of AgNPs/AuNPs/glass system at higher annealing temperature. By introducing AuNPs on glass prior to AgNPs deposition, novel properties such as limited Ag ion diffusion and evaporation were found and problems previously encountered in AgNPs/glass system were avoided. The proposed AgNPs/AuNPs/glass system can be useful in plasmonic applications such as chroma filters and photonic devices.
•Silver nanoparticles deposited on thin gold nanoparticles layer/glass substrates•Sputtering with inert gas condensation technique was applied•Initial AuNPs layer effects AgNPs surface structure via post annealing•Limited Ag ions diffusion and evaporation were observed due to initial AuNPs layer•Problems previously met in AgNPs/glass were avoided in AuNPs/AgNPs/glass system
Empirical evidence increasingly suggests that supervisors' support significantly impacts employees' commitment to change and possibly diminishes their turnover intention. This study, conducted at a ...government university in Oman, investigated a mediated-effects model of leadership support and faculty turnover intention. The model proposes leadership support (supervisor support) as an antecedent of faculty turnover intention and commitment to accreditation-related change as a mediator in the leadership support-faculty turnover intention relationship. Survey data were collected from faculty members (n = 221) and analysed using structural equation modelling. Findings showed that leadership support greatly contributes to low faculty turnover intention and improves faculty's commitment to accreditation, which has a significant and direct impact on their turnover intention. Therefore, university-level leadership support, both directly and indirectly, shapes faculty's commitment to change. These results have significant implications for practice as well as for future research related to leadership support for academic accreditation in higher education institutions.
IntroductionWith the spread of COVID-19 around the world, several interventions have been reported to be useful to control disease transmission. However, the impact of the pandemic on the mental ...health of medical students is underreported in the Arab world. This study aimed to explore the rates of depression, anxiety, and stress among medical students at Sultan Qaboos University (SQU) and to identify the factors associated with a higher risk of these mental disruptions.MethodThis was a cross-sectional study where medical students were approached to answer an online questionnaire via emails from the administrative affairs in the College of Medicine in SQU from 16/01/2021 to 18/05/2021. A 21-item depression, anxiety, and stress (DASS-21) scale was used as a self-reporting tool to measure the negative feelings of depression, anxiety, and stress.ResultsOut of 700 students, 184 (26.3%) students responded fully to the study questionnaire. More than half of the participants were females (58.7%, n=108), and the mean (SD) age was 20.31 (1.642). Most students were Omani (93.5%, n=172), and 34.2% (n=63) lived in Muscat. More than half of the students (51.6%) were in phase 2 of the academic years, in which the majority were considered within the cohort ≥2017 (81%, n=149), with a mean (SD) GPA of 2.9 (1.5). Scores from the DASS-21 scale showed that 29.4% vs 27.2% vs 14.7% had extremely severe depression vs anxiety and vs stress. The proportion of students who reported lower GPAs was significantly associated with higher scores of severe-to-extremely-severe depression (P=0.001), anxiety (P=<0.001), and stress (P=0.001). Living in Muscat vs other regions was associated with severe anxiety and stress (P=0.038 and P=0.007, respectively).ConclusionSimilar to a few studies in Oman, this study confirms the high rates of depression, anxiety, and stress among medical students during the COVID-19 pandemic. Results may be utilized to alert decision-makers, student academic council, and academic authority to the need to adopt a preventive mental health policy and design guidelines with resilience measures for college students, including prolonged cognitive-behavioral interventions and recovery programs.
Single-phased Ru
3+
-doped LaFeO
3
nanocrystalline particles (6-70 nm), with nominal compositions of LaFe
1-
x
Ru
x
O
3
(
x
= 0.00, 0.015, 0.03, 0.05 and 0.08), were prepared using mechano-synthesis ...at temperatures that are
ca.
400 °C- 700 °C lower than those used to synthesize cation-doped LaFeO
3
conventionally. The Ru
3+
ions are found to substitute exclusively for the Fe
3+
ones at the octahedral sites of the perovskite-related structure. The lattice parameters of all samples are suggestive of a weak Jahn-Teller-like distortion as opposed to the normal distortion of orthorhombic perovskites.
57
Fe Mössbauer measurements for all samples show the Fe
3+
ions to be in high-spin state implying that the observed lattice distortion is due to particle-size surface-induced disorder rather than the electronic degeneracy associated with the normal Jahn-Teller distortion. The decrease in the Mössbauer hyperfine magnetic fields with increasing Ru
3+
content is attributed mainly to particle size reduction rather than the cationic substitution of Fe
3+
by the Ru
3+
. A monotonic decrease of the optical band gap from 2.17 eV (
x
= 0.00) to 1.79 eV (
x
= 0.08) was observed, revealing how doping with Ru
3+
affects the optical absorption of the LaFeO
3
nanoparticles.
Background The integration of public health functions in primary care is not well-defined in the literature. This paper examines the perceptions of healthcare workers on public health services in ...primary care, as well as the challenges and views on strengthening the integration of public health functions in a primary care setting in Oman. Methodology This qualitative study (employing a face-to-face interview) was conducted in a primary healthcare setting in Muscat from January 1, 2022, to May 31, 2022. This study is based on interpretative phenomenological analysis using purposeful sampling. Participants were interviewed to answer the study questions. The targeted participants included directors and other official personnel, physicians, nurses, pharmacists, nutritionists, health educators, and lab technicians. Verbal consent was obtained from the participants before the interview, and all responses were anonymously audio recorded, transcribed verbatim, and analyzed using thematic analysis. Results A total of 10 primary care providers were interviewed once for 30 minutes over a two-week period. All participants were females apart from one male participant. The study included three physicians, five nurses, one pharmacist, and one nutritionist. All participants had over 10 years of experience as primary care providers at the time of the interview. The main themes were a lack of awareness of public health services in a primary care setting, challenges to practicing public health in a primary care setting, and recommendations to strengthen the integration of public health services in primary care. In general, there were inconsistent views on public health services in a primary care setting, and the interactions between the functions were not clear. Participants reported an absence of clear guidelines, training, and competencies for public health in a primary care setting. Building public health capacities and reforming the health system were highly recommended to integrate public health into primary health care. Conclusions Understanding how public health and primary care interact is crucial to improve population health. Building competencies and supportive health systems are required for the effective integration of public health in primary care settings.
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