Applications based on aggregates of magnetic nanoparticles are becoming increasingly widespread, ranging from hyperthermia to magnetic recording. However, although some uses require a collective behavior, other need a more individual-like response, the conditions leading to either of these behaviors are still poorly understood. Here we use nanoscaleuniform binary random dense mixtures with different proportions of oxide magnetic nanoparticles with low/high anisotropy as a valuable tool to explore the crossover from individual to collective behavior. Two different anisotropy scenarios have been studied in two series of binary compacts: M1, comprising maghemite (-Fe2O3) nanoparticles of different sizes (9.0 nm / 11.5 nm) with barely a factor of 2 between their anisotropy energies and M2, mixing equally-sized pure maghemite (low-anisotropy) and Co-doped maghemite (high-anisotropy) nanoparticles with a large difference in anisotropy energy (ratio > 8).Interestingly, while the M1 series exhibits collective behavior typical of strongly-coupled dipolar systems, the M2 series presents a more complex scenario where different magnetic properties resemble either "individual-like" or "collective", crucially emphasizing that the collective character must be ascribed to specific properties and not to the system as a whole.The strong differences between the two series, offer new insight (systematically ratified by simulations) into the subtle interplay between dipolar interactions, local anisotropy and sample heterogeneity, to determine the behavior of dense assemblies of magnetic nanoparticles.peak temperature TMAX (Thalt 2· TMAX /3), then resumed to the lowest temperature (10 K).Subsequently, the M(T) curve is registered under exactly the same conditions as the reference ZFC curve. DCD (direct current demagnetization) remanence curves were measured by initially saturating the sample (in H = -50 kOe) and then measuring the moment after application and removal of progressively increasing reverse fields. 76 Finally, the temperature dependence of the ac susceptibility was recorded at 10 Hz using a field amplitude of 1 Oe.All the magnetic measurements were performed using a MPMS SQUID magnetometer from Quantum Design.Monte Carlo simulations. Monte Carlo simulations were carried out using the mesoscopic three-spins model 53 (see Supporting Information for details). [77][78][79]
Columbu ( a *), marCella Palomba ( b ), fabio Sitzia ( a ) & miriam r. murgia ( a )
Due to their inherent chemical complexity and their refractory nature, the obtainment of highly dense and single-phase high entropy (HE) diborides represents a very hard target to achieve. In this framework, homogeneous (Hf0.2Nb0.2Ta0.2Mo0.2Ti0.2)B2, (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2, and (Hf0.2Zr0.2Nb0.2Mo0.2Ti0.2)B2 ceramics with high relative densities (97.4, 96.5, and 98.2%, respectively) were successfully produced by spark plasma sintering (SPS) using powders prepared by self-propagating high-temperature synthesis (SHS). Although the latter technique did not lead to the complete conversion of initial precursors into the prescribed HE phases, such a goal was fully reached after SPS (1950 °C/20 min/20 MPa). The three HE products showed similar and, in some cases, even better mechanical properties compared to ceramics with the same nominal composition attained using alternative processing methods. Superior Vickers hardness and elastic modulus values were found for the (Hf0.2Nb0.2Ta0.2Mo0.2Ti0.2)B2 and the (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2 systems, i.e., 28.1 GPa/538.5 GPa and 28.08 GPa/498.1 GPa, respectively, in spite of the correspondingly higher residual porosities (1.2 and 2.2 vol.%, respectively). In contrast, the third ceramic, not containing tantalum, displayed lower values of these two properties (25.1 GPa/404.5 GPa). However, the corresponding fracture toughness (8.84 MPa m1/2) was relatively higher. This fact can be likely ascribed to the smaller residual porosity (0.3 vol.%) of the sintered material.
No abstract
(1) Background: Trismus clinically manifests as a reduction of the buccal opening and restricted mouth opening due to different etiologies, but it is often associated with traumatic phenomena. Several treatments have been proposed such as physiotherapy exercises, cryotherapy, laser therapy, hyaluronic acid and platelet-rich fibrin infiltration, but the gold standard is represented by drug therapy based on corticosteroids and NSAIDs, currently the most documented in the scientific literature. Capacitive-resistive electric transfer (Cret) therapy is used to treat musculoskeletal injuries. Cret is a non-invasive electrothermal treatment classified as deep thermo-therapy. (2) Patient: We would like to document a case of particularly traumatic trismus in a 12-year-old patient, not responsive to previous pharmacological therapy and treated with a radiofrequency device called Velvet temporomandibular joint (TMJ). Five capacitive and resistive diathermy sessions with the device were performed. The first four sessions were performed every 4 days and the fifth after 5 days. (3) Result: The maximum opening of the mouth was 10 mm at the initial stage and 38 mm at the end of the six sessions. Pain regressed after the second appointment. (4) Conclusions: Clinical studies with a good number of samples need to be conducted to evaluate the effectiveness of this device which has proved to be an excellent treatment for this refractory case to conventional therapies. Finally, it may be useful to define precise and replicable protocols to make this therapy suitable for patients with TMJ disorders.
(1) Background: Traumatic dental injuries constitute a major global health problem. Primary deciduous teeth of the upper frontal group are frequently affected by trauma, especially at an early age. It is important to treat primary traumatic injuries because early tooth loss can lead to aesthetic and functional alterations. The most common injuries are extrusion, lateral luxation, and intrusion. Root fracture is a less common complication that can lead to tooth extraction if not properly diagnosed and managed. However, there are a lack of data regarding primary root fracture treatment. The literature was reviewed to study the current knowledge on the treatment of these injuries, and to propose an operative protocol based on the results obtained. (2) Methods: A literature search was performed on Web of Science, PubMed/MEDLINE, and SCOPUS. The research focused on the following features: age of the patient; localization of the root fracture and type of displacement suffered (intrusive, extrusive, or lateral); type of emergency treatment or diagnostic test performed and their compliance with IADT guidelines; follow-up duration. (2) Results: Only 8 articles fully met the inclusion criteria, with a total of 46 patients and 62 root fractures. Out of a total of 62 root fractures, regarding only upper incisors, the most common treatment was splinting (n = 39) for a period ranging from 3 weeks to 3 months (with an average of six weeks). No treatment was performed for 23 of the root fractures. The splinting performed in most of the included cases was semi-rigid, with the splint held in place using a composite resin material. An orthodontic splint using brackets and 0.5 mm stainless steel wire was used in only in one study. (4) Conclusions: We deduced that the root fracture of primary teeth is a rare traumatic dental injury that can cause numerous complications, such as eruptive problems in the permanent teeth. Correct radiological diagnosis, immediate repositioning and semi-rigid splinting could be conservative methods to prevent premature tooth loss in very young patients.
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