Synthesis and Magnetic Properties of Cobalt Ferrite (CoFe2O4) Nanoparticles Prepared by Wet Chemical Route

Magnetic nanoparticles of cobalt ferrite have been synthesized by wet chemical method using stable ferric and cobalt salts with oleic acid as the surfactant. X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM) confirmed the formation of single phase cobalt ferrite nanoparticles in the range 15-48nm depending on the annealing temperature and time. The size of the particles increases with annealing temperature and time while the coercivity goes through a maximum, peaking at around 28nm. A very large coercivity (10.5kOe) is observed on cooling down to 77K while typical blocking effects are observed below about 260K. The high field moment is observed to be small for smaller particles and approaches the bulk value for large particles.Comment: 18 pages, accepted in JMMM, (May, 2006

Magnetic response of core-shell cobalt ferrite nanoparticles at low temperature

Cobaltferritenanoparticles (size: 26±4nm) have been synthesized by coprecipitation route. The coercivity of nanoparticles follows a simple model of thermal activation of particle moments over the anisotropy barrier in the temperature range of 30–300K in accordance with Kneller’s law; however, at low temperatures

Exchange Bias and Vertical Shift in CoFe2O4 nanoparticles

Magnetic properties of core-shell cobalt ferrite nanoparticles 15 to 48nm prepared by a sol-gel route have been studied. It is shown that the coercivity follows non-monotonic size dependence varying as 1/d above the maximum (d is the particle size). Field cooled magnetization exhibited both horizontal (exchange bias) and vertical shifts. The exchange bias is understood as originating at the interface between a surface region with structural and spin disorder and a core ferrimagnetic region. The dependence of the exchange bias and vertical shifts on the particle sizes and cooling fields are found to have significant differences and the differences are explained in the light of recent results which suggest that both weakly and strongly pinned spins are present at the interface. It is suggested that the exchange bias is dominated by the weakly pinned spins while the vertical shift is affected by the strongly pinned ones.Comment: 2

Return to Sport After Turf Toe Injuries: A Systematic Review and Meta-analysis

A grant from the One-University Open Access Fund at the University of Kansas was used to defray the author's publication fees in this Open Access journal. The Open Access Fund, administered by librarians from the KU, KU Law, and KUMC libraries, is made possible by contributions from the offices of KU Provost, KU Vice Chancellor for Research & Graduate Studies, and KUMC Vice Chancellor for Research. For more information about the Open Access Fund, please see http://library.kumc.edu/authors-fund.xml.Background: The prevalence of turf toe injuries has increased in recent years. However, uncertainty remains as to how to optimally treat turf toe injuries and the implications that the severity of the injury has on outcomes, specifically return to sport (RTS). Purpose: To determine RTS based on treatment modality and to provide clinicians with additional information when comparing operative versus nonoperative treatment of turf toe injuries in athletes. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review and meta-analysis was performed using the PubMed/Ovid MEDLINE/PubMed Central databases (May 1964 to August 2018) per PRISMA-IPD (Preferred Reporting Items for Systematic Reviews and Meta-Analyses of Individual Participant Data) guidelines. RTS, treatment, severity of injury, athletic position, and sport were recorded and analyzed. Results: Of 858 identified studies, 12 met the criteria for the final meta-analysis. The studies included 112 athletes sustaining a total of 121 turf toe injuries; 63 (52.1%) of these injuries were treated surgically, while 58 (47.9%) were treated nonoperatively, and 53.7% were classified by the grade of injury (grade I, n = 1; grade II, n = 9; grade III, n = 55). Overall, 56 (46.3%) injuries could not be classified based on the data provided and were excluded from the final analysis. The median time to RTS for patients treated nonoperatively was 5.85 weeks (range, 3.00-8.70 weeks) compared with 14.70 weeks (range, 6.00-156.43 weeks) for patients treated surgically (P < .001); however, there was variability in the grade of injury between the 2 groups. Similarly, patients who sustained grade II injuries returned to sport more quickly (8.70 weeks) than patients who had a grade I (13.04 weeks) or grade III injury (16.50 weeks) (P = .016). The amount of time required to RTS was significantly influenced by the athlete’s level of play (16.50 weeks for both high school and college levels; 14.70 weeks for professional level) (P = .018). Conclusion: The time to RTS for an athlete who suffers from a turf toe injury is significantly influenced by the severity of injury and the athlete’s level of competition. Professional athletes who suffer from turf toe injuries RTS sooner than both high school and college athletes. However, there are a limited number of high-level studies evaluating turf toe injuries in the athletic population. Further research is necessary to clearly define the appropriate treatment and RTS protocols based on sport, position, and level of play

Medical students’ preparedness for professional activities in early clerkships

Background Sufficient preparedness is important for transitions to workplace participation and learning in clinical settings. This study aims to analyse medical students’ preparedness for early clerkships using a three-dimensional, socio-cognitive, theory-based model of preparedness anchored in specific professional activities and their supervision level. Methods Medical students from a competency-based undergraduate curriculum were surveyed about preparedness for 21 professional activities and level of perceived supervision during their early clerkships via an online questionnaire. Preparedness was operationalized by the three dimensions of confidence to carry out clerkship activities, being prepared through university teaching and coping with failure by seeking support. Factors influencing preparedness and perceived stress as outcomes were analysed through step-wise regression. Results Professional activities carried out by the students (n = 147; 19.0%) and their supervision levels varied. While most students reported high confidence to perform the tasks, the activity-specific analysis revealed important gaps in preparation through university teaching. Students regularly searched for support in case of difficulty. One quarter of the variance of each preparedness dimension was explained by self-efficacy, supervision quality, amount of prior clerkship experience and nature of professional activities. Preparedness contributed to predicting perceived stress. Conclusions The applied three-dimensional concept of preparedness and the task-specific approach provided a detailed and meaningful view on medical students’ workplace participation and experiences in early clerkships

Effect of Crystallographic Texture on Magnetic Characteristics of Cobalt Nanowires

Cobalt nanowires with controlled diameters have been synthesized using electrochemical deposition in etched ion-track polycarbonate membranes. Structural characterization of these nanowires with diameter 70, 90, 120 nm and length 30 μm was performed by scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction techniques. The as-prepared wires show uniform diameter along the whole length and X-ray diffraction analysis reveals that [002] texture of these wires become more pronounced as diameter is reduced. Magnetic characterization of the nanowires shows a clear difference of squareness and coercivity between parallel and perpendicular orientations of the wires with respect to the applied field direction. In case of parallel applied field, the coercivity has been found to be decreasing with increasing diameter of the wires while in perpendicular case; the coercivity observes lower values for larger diameter. The results are explained by taking into account the magnetocrystalline and shape anisotropies with respect to the applied field and domain transformation mechanism when single domain limit is surpassed