Extreme Domain Wall Speeds under Ultrafast Optical Excitation.

Time-resolved ultrafast EUV magnetic scattering was used to test a recent prediction of >10 km/s domain wall speeds by optically exciting a magnetic sample with a nanoscale labyrinthine domain pattern. Ultrafast distortion of the diffraction pattern was observed at markedly different timescales compared to the magnetization quenching. The diffraction pattern distortion shows a threshold dependence with laser fluence, not seen for magnetization quenching, consistent with a picture of domain wall motion with pinning sites. Supported by simulations, we show that a speed of ≈66 km/s for highly curved domain walls can explain the experimental data. While our data agree with the prediction of extreme, nonequilibrium wall speeds locally, it differs from the details of the theory, suggesting that additional mechanisms are required to fully understand these effects.

Inertial Spin Dynamics in Epitaxial Cobalt Films.

We investigate the spin dynamics driven by terahertz magnetic fields in epitaxial thin films of cobalt in its three crystalline phases. The terahertz magnetic field generates a torque on the magnetization which causes it to precess for about 1 ps, with a subpicosecond temporal lag from the driving force. Then, the magnetization undergoes natural damped THz oscillations at a frequency characteristic of the crystalline phase. We describe the experimental observations solving the inertial Landau-Lifshitz-Gilbert equation. Using the results from the relativistic theory of magnetic inertia, we find that the angular momentum relaxation time η is the only material parameter needed to describe all the experimental evidence. Our experiments suggest a proportionality between η and the strength of the magnetocrystalline anisotropy.

Nanoscale Transient Magnetization Gratings Created and Probed by Femtosecond Extreme Ultraviolet Pulses.

We utilize coherent femtosecond extreme ultraviolet (EUV) pulses from a free electron laser (FEL) to generate transient periodic magnetization patterns with periods as short as 44 nm. Combining spatially periodic excitation with resonant probing at the M-edge of cobalt allows us to create and probe transient gratings of electronic and magnetic excitations in a CoGd alloy. In a demagnetized sample, we observe an electronic excitation with a rise time close to the FEL pulse duration and ∼0.5 ps decay time indicative of electron-phonon relaxation. When the sample is magnetized to saturation in an external field, we observe a magnetization grating, which appears on a subpicosecond time scale as the sample is demagnetized at the maxima of the EUV intensity and then decays on the time scale of tens of picoseconds via thermal diffusion. The described approach opens multiple avenues for studying dynamics of ultrafast magnetic phenomena on nanometer length scales.

A UHV MOKE magnetometer complementing XMCD-PEEM at the Elettra Synchrotron.

We report on a custom-built UHV-compatible Magneto-Optical Kerr Effect (MOKE) magnetometer for applications in surface and materials sciences, operating in tandem with the PhotoEmission Electron Microscope (PEEM) endstation at the Nanospectroscopy beamline of the Elettra synchrotron. The magnetometer features a liquid-nitrogen-cooled electromagnet that is fully compatible with UHV operation and produces magnetic fields up to about 140 mT at the sample. Longitudinal and polar MOKE measurement geometries are realized. The magneto-optical detection is based on polarization analysis using a photoelastic modulator. The sample manipulation system is fully compatible with that of the PEEM, making it possible to exchange samples with the beamline endstation, where complementary X-ray imaging and spectroscopy techniques are available. The magnetometer performance is illustrated by experiments on cobalt ultra-thin films, demonstrating close to monolayer sensitivity. The advantages of combining in situ growth, X-ray Magnetic Circular Dichroism imaging (XMCD-PEEM) and MOKE magnetometry into a versatile multitechnique facility are highlighted.

Optical Frequency Up-Conversion of the Ferromagnetic Resonance in an Ultrathin Garnet Mediated by Magnetoelastic Coupling.

We perform ultrafast pump-probe measurements on a nanometer-thick crystalline Bi-doped yttrium iron garnet film with perpendicular magnetic anisotropy. Tuning the photon energy of the pump laser pulses above and below the material's band gap, we trigger ultrafast optical and spin dynamics via both one- and two-photon absorption. Contrary to the common scenario, the optically induced excitation induces an increase up to 20% of the ferromagnetic resonance frequency of the material. We explain this unexpected result in terms of a modification of the magnetic anisotropy caused by a long-lived photo-induced strain, which transiently and reversibly modifies the magnetoelastic coupling in the material. Our results disclose the possibility to optically increase the magnetic eigenfrequency in nanometer-thick magnets.

Effects of remote digital monitoring on oral hygiene of orthodontic patients: a prospective study.

BACKGROUND: Remote digital monitoring during orthodontic treatment can help patients in improving their oral hygiene performance and reducing the number of appointments due to emergency reasons, especially in time of COVID-19 pandemic where non-urgent appointments might be discouraged. METHODS: Thirty patients scheduled to start an orthodontic treatment were divided into two groups of fifteen. Compared to controls, study group patients were provided with scan box and cheek retractor (Dental Monitoring®) and were instructed to take monthly intra-oral scans. Plaque Index (PI), Gingival Index (GI), and White Spot Lesions (WSL) were recorded for both groups at baseline (t0), every month for the first 3 months (t1, t2, t3), and at 6 months (t4). Carious Lesions Onset (CLO) and Emergency Appointments (EA) were also recorded during the observation period. Inter-group differences were assessed with Student's t test and Chi-square test, intra-group differences were assessed with Cochran's Q-test (significance α = 0.05). RESULTS: Study group patients showed a significant improvement in plaque control at t3 (p = 0.010) and t4 (p = 0.039), compared to control group. No significant difference was observed in the number of WSL between the two groups. No cavities were detected in the study group, while five CLO were diagnosed in the control group (p = 0.049). A decreased number of EA was observed in the study group, but the difference was not significant. CONCLUSIONS: Integration of a remote monitoring system during orthodontic treatment was effective in improving plaque control and reducing carious lesions onset. The present findings encourage orthodontists to consider this technology to help maintaining optimal oral health of patients, especially in times of health emergency crisis.

Anisotropic X-Ray Scattering of Transiently Oriented Water.

We study the structural dynamics of liquid water by time-resolved anisotropic x-ray scattering under the optical Kerr effect condition. In this way, we can separate the anisotropic scattering decay of 160 fs from the delayed temperature increase of ∼0.1 K occurring at 1 ps and quantify transient changes in the O-O pair distribution function. Polarizable molecular dynamics simulations reproduce well the experiment, indicating transient alignment of molecules along the electric field, which shortens the nearest-neighbor distances. In addition, analysis of the simulated water local structure provides evidence that two hypothesized fluctuating water configurations exhibit different polarizability.

Nonlinear Magnetization Dynamics Driven by Strong Terahertz Fields.

We present a comprehensive experimental and numerical study of magnetization dynamics in a thin metallic film triggered by single-cycle terahertz pulses of ∼20 MV/m electric field amplitude and ∼1 ps duration. The experimental dynamics is probed using the femtosecond magneto-optical Kerr effect, and it is reproduced numerically using macrospin simulations. The magnetization dynamics can be decomposed in three distinct processes: a coherent precession of the magnetization around the terahertz magnetic field, an ultrafast demagnetization that suddenly changes the anisotropy of the film, and a uniform precession around the equilibrium effective field that is relaxed on the nanosecond time scale, consistent with a Gilbert damping process. Macrospin simulations quantitatively reproduce the observed dynamics, and allow us to predict that novel nonlinear magnetization dynamics regimes can be attained with existing tabletop terahertz sources.

Treatment of recurrent aphthous stomatitis (RAS; aphthae; canker sores) with a barrier forming mouth rinse or topical gel formulation containing hyaluronic acid: a retrospective clinical study.

BACKGROUND: Use of hyaluronic acid-based products has become a valuable alternative to drug-based approaches in the treatment of recurrent aphthous stomatitis (RAS). The presented study aimed to investigate the effect of a barrier forming hyaluronic acid containing mouth wash or a topical gel formulation on the healing of RAS and patient's quality of life. METHODS: For this single-center retrospective study, medical records of the Dental School of the University of Brescia were screened for adult and systemically health patients suffering from minor recurrent aphthous stomatitis (RAS) and treated with either a barrier forming, hyaluronic acid containing mouth wash (GUM® AftaClear® rinse) or a topical gel (GUM® AftaClear® gel) in 2015. All patients fulfilling the in-/exclusion criteria and presenting full data sets on lesion diameter, lesion color, as well as pain perception for baseline (day 0) and 4 and 7 days after treatment were enrolled into the presented study. RESULTS: Out of 60 screened patients, a total of 20 patients treated with the Rinse formulation and 25 treated with the Gel formulation were eligible for the enrollment into this study. Both groups showed equal distribution in patient's age, sex and presented a similar mean lesion size (3.0 ± 1.0 mm), lesion color distribution as well as pain perception at baseline. All patients showed significant normalization of lesion color, reduction of pain, and lesion dimension within the course of their treatment. After 7 days, the mean percentage of lesion reduction was highly significant for both groups attaining 77.4 ± 30.1% in the Rinse group and 81.2 ± 23.1% in the Gel group with a complete lesion closure obtained in 60 and 56% of the cases, respectively. However, a significant (p < 0.05) higher percentage of lesions in the Gel group (72%) compared to the Rinse group (40%) showed an improvement in lesion size already after 3 days. CONCLUSIONS: Within the limitation of retrospective design, it can be concluded that both the barrier forming hyaluronic acid containing mouth rinse as well as the topical gel formulation are effective in the treatment of minor recurrent aphthous stomatitis (RAS), with a trend for an earlier healing onset for the topical Gel formulation.

Anti-reflection coating design for metallic terahertz meta-materials.

We demonstrate a silicon-based, single-layer anti-reflection coating that suppresses the reflectivity of metals at near-infrared frequencies, enabling optical probing of nano-scale structures embedded in highly reflective surroundings. Our design does not affect the interaction of terahertz radiation with metallic structures that can be used to achieve terahertz near-field enhancement. We have verified the functionality of the design by calculating and measuring the reflectivity of both infrared and terahertz radiation from a silicon/gold double layer as a function of the silicon thickness. We have also fabricated the unit cell of a terahertz meta-material, a dipole antenna comprising two 20-nm thick extended gold plates separated by a 2 µm gap, where the terahertz field is locally enhanced. We used the time-domain finite element method to demonstrate that such near-field enhancement is preserved in the presence of the anti-reflection coating. Finally, we performed magneto-optical Kerr effect measurements on a single 3-nm thick, 1-µm wide magnetic wire placed in the gap of such a dipole antenna. The wire only occupies 2% of the area probed by the laser beam, but its magneto-optical response can be clearly detected. Our design paves the way for ultrafast time-resolved studies, using table-top femtosecond near-infrared lasers, of dynamics in nano-structures driven by strong terahertz radiation.

Polarizability and magnetoplasmonic properties of magnetic general nanoellipsoids.

An approach to compute the polarizability tensor of magnetic nanoparticles having general ellipsoidal shape is presented. We find a surprisingly excellent quantitative agreement between calculated and experimental magneto-optical spectra measured in the polar Kerr configuration from nickel nanodisks of large size (exceeding 100 nm) with circular and elliptical shape. In spite of its approximations and simplicity, the formalism presented here captures the essential physics of the interplay between magneto-optical activity and the plasmonic resonance of the individual particle. The results highlight the key role of the dynamic depolarization effects to account for the magneto-optical properties of plasmonic nanostructures.

Tuning the magneto-optical response of nanosize ferromagnetic Ni disks using the phase of localized plasmons.

We explore the influence of the phase of localized plasmon resonances on the magneto-optical activity of nanoferromagnets. We demonstrate that these systems can be described as two orthogonal damped oscillators coupled by the spin-orbit interaction. We prove that only the spin-orbit induced transverse plasmon plays an active role on the magneto-optical properties by controlling the relative amplitude and phase lag between the two oscillators. Our theoretical predictions are fully confirmed by magneto-optical Kerr effect and optical extinction measurements in nanostructures of different size and shape.

Self-ligating fully customized lingual appliance and chair-time reduction: a typodont study followed by a randomized clinical trial.

In this study, we tested the hypothesis that self-ligation can reduce the chair time necessary for inserting and removing the archwire in a fully customized, multi-bracket, orthodontic, lingual appliance. A permuted-block, randomized trial design was employed to treat seven patients, each with Incognito(®) lingual appliances and Harmony(®) self-ligating lingual appliances. Three operators (a third year resident in orthodontics, an orthodontic specialist, and an experienced lingual orthodontist) were instructed, and they were allowed to familiarize themselves with two typodonts. Next, the operators were asked to insert and remove a.014 NiTi customized archwire for each patient, and they were timed. The time required for removing and inserting archwires decreased proportionally with operator experience: it was shorter with self-ligating appliances (114.82±18.06 seconds versus 595.83±289.09 seconds, P < 0.001) and when testing the typodonts' performances (480.61±285.74 seconds versus 518.65±296.97 seconds, P < 0.001). However, differences between operators were smaller when using typodonts (31.77±21.19 seconds versus 43.87±27.06 seconds, P < 0.001) and with self-ligation (15.17±9.29 seconds versus 45.37±25.44 seconds, P < 0.001). In vivo performance improved after typodont training, allowing for difference reductions between operators. Lingual self-ligation appears to require less hands-on ability and training of the orthodontist, for reduction of chair time.

Terahertz Time-Domain Spectroscopy in Reflection Configuration for Inorganic and Mineral Pigment Identification.

This work demonstrates terahertz time-domain spectroscopy (THz-TDS) in reflection configuration on a class of inorganic and mineral pigments. The technique is validated for pictorial materials against the limitations imposed by the back-reflection of the THz signal, such as weak signal intensity, multiple signal losses and distortion, as well as the current scarce databases. This work provides a detailed description of the experimental procedure and method used for the determination of material absorption coefficient of a group of 10 pigments known to be used in ancient frescoes, that are, Cu-based (azurite, malachite, and Egyptian blue), Pb-based (minium and massicot), Fe-based (iron oxide yellow, dark ochre, hematite, and Pompeii red) pigments and mercury sulfide (cinnabar), and classified the vibrational modes of the molecular oxides and sulfides for material identification. The results of this work showed that the mild signal in reflection configuration does not limit the application of THz-TDS on inorganic and mineral pigments as long as (i) the THz signal is normalized with a highly reflective reference sample, (ii) the secondary reflected signals from inner interfaces are removed with a filtering procedure, and (iii) the limitations at high frequencies imposed by the dynamic range of the instrument are considered. Under these assumptions, we were able to differentiate molecular phases of the same metal and identify azurite, Egyptian blue, minium, and cinnabar, isolating the molecular vibrations up to 125 cm-1. The established approach demonstrated to be reliable, and it can be extended for the study of other materials, well beyond the reach of the heritage domain.

Designer magnetoplasmonics with nickel nanoferromagnets.

We introduce a new perspective on magnetoplasmonics in nickel nanoferromagnets by exploiting the phase tunability of the optical polarizability due to localized surface plasmons and simultaneous magneto-optical activity. We demonstrate how the concerted action of nanoplasmonics and magnetization can manipulate the sign of rotation of the reflected light's polarization (i.e., to produce Kerr rotation reversal) in ferromagnetic nanomaterials and, further, how this effect can be dynamically controlled and employed to devise conceptually new schemes for biochemosensing.

Proposed parameters of optimal central incisor positioning in orthodontic treatment planning: A systematic review.

OBJECTIVE: Planning of incisal position is crucial for optimal orthodontic treatment outcomes due to its consequences on facial esthetics and occlusion. A systematic summary of the proposed parameters is presented. METHODS: Studies on Google Scholar©, PubMed©, and Cochrane Library, providing quantitative information on optimal central incisor position were included. RESULTS: Upper incisors supero-inferior position (4-5 mm to upper lip, 67-73 mm to axial plane through pupils), antero-posterior position (3-4 mm to Nasion-A, 3-6 mm to A-Pogonion, 9-12 mm to true vertical line, 5 mm to A-projection, 9-10 mm to coronal plane through pupils), bucco-lingual angulation (4-7° to occlusal plane perpendicular on models, 20-22° to Nasion-A, 57-58° to upper occlusal plane, 16-20° to coronal plane through pupils, 108-110° to anterior-posterior nasal spine), mesio-distal angulation (5° to occlusal plane perpendicular on models). Lower incisors supero-inferior position (41-48 mm to soft-tissue mandibular plane), antero-posterior position (3-4 mm to Nasion-B, 1-3 mm to A-Pogonion, 12-15 mm to true vertical line, 6-8 mm to coronal plane through pupils), bucco-lingual angulation (1-4° to occlusal plane perpendicular on models, 87-94° to mandibular plane, 68° to Frankfurt plane, 22-25° to Nasion-B, 105° to occlusal plane, 64° to lower occlusal plane, 21° to A-Pogonion), mesio-distal angulation (2° to occlusal plane perpendicular on models). CONCLUSIONS: Although these findings can provide clinical guideline, they derive from heterogeneous studies in terms of subject characteristics and reference methods. Therefore, the optimal incisal position remains debatable.

Remote digital monitoring during the retention phase of orthodontic treatment: A prospective feasibility study.

Objective: To evaluate if a remote digital monitoring system added at the end of orthodontic treatment could positively influence the retention phase by reducing the occurrence of misfit of removable appliances, number of emergency appointments (EA), and orthodontic relapse. Methods: Twenty-seven patients who completed active orthodontic treatment were divided into the study and control groups. In addition to the standard chairside follow-up appointments at month 1 (T1), month 3 (T2), month 6 (T3), the study group patients were monitored using Dental Monitoring® with monthly intra-oral scans. Occurrence of misfit of removable retainers, number of EAs, and intercanine width change were recorded for both groups. Differences in EAs and retainer fit were assessed using the chi-square test. Intra-group and inter-group differences in the intercanine width were assessed with Friedman test and Mann-Whitney U test, respectively (α = 0.05). Results: The study group showed a significantly lower occurrence of misfit of removable retainers (p = 0.027) compared to the control group. No significant inter- and intra-group difference was found in the EAs and intercanine width change at each time-point. Conclusions: Integrating remote monitoring systems, such as Dental Monitoring®, to the retention phase of the orthodontic treatment may lower the occurrence of misfit of removable retainers. However, a small sample size and a short observation period limit the strength of this evidence. These preliminary results tentatively suggest that remote monitoring technologies may be beneficial, especially during the COVID-19 pandemic, when the regularity of in-office visits might be disrupted.

Probable Silodosin-Induced Diplopia.

Diplopia, or double vision, is a symptom resulting from the perception of two images of a single object. We report a case of a possible silodosin-induced diplopia never reported before in the literature. We suggest that binocular diplopia should be considered in people assuming silodosin even if further studies should be conducted to explore possible pathogenetic mechanisms.

Nonequilibrium sub-10 nm spin-wave soliton formation in FePt nanoparticles.

Magnetic nanoparticles such as FePt in the L10 phase are the bedrock of our current data storage technology. As the grains become smaller to keep up with technological demands, the superparamagnetic limit calls for materials with higher magnetocrystalline anisotropy. This, in turn, reduces the magnetic exchange length to just a few nanometers, enabling magnetic structures to be induced within the nanoparticles. Here, we describe the existence of spin-wave solitons, dynamic localized bound states of spin-wave excitations, in FePt nanoparticles. We show with time-resolved x-ray diffraction and micromagnetic modeling that spin-wave solitons of sub-10 nm sizes form out of the demagnetized state following femtosecond laser excitation. The measured soliton spin precession frequency of 0.1 THz positions this system as a platform to develop novel miniature devices.

Treatment of ankylosed deciduous molars with or without permanent successors in children and adolescents: a systematic review.

INTRODUCTION: The aim of this systematic review was to provide guidelines for decision-making during orthodontic treatment planning of infra-occluded deciduous molars with or without their successors in children and adolescents. EVIDENCE ACQUISITION: Computerized search was conducted on Medline via PubMed, and Cochrane Library. Articles published until 2020 in English language were analyzed following the Preferred Reporting Items for Systematic Reviews (PRISMA) Checklist. Observational and interventional longitudinal studies reporting the treatment of ankylosed deciduous molars with or without successor tooth in 3 to 15-year-old patients were included. EVIDENCE SYNTHESIS: In case of ankylosis with presence of successor, exfoliation took place in 77% of teeth, while extraction involved 23%. Infra-occlusion happened in 53% of teeth (worsening in 52%), alveolar bone loss in 37%, mesial tipping of first permanent molar in 5%, and over-eruption of antagonist in no cases (after exfoliation and eruption of successor). In case of ankylosis without successor, exfoliation took place in 1% of teeth, progression of infra-occlusion in 42%, progression of root resorption in 58%, development of mesial tipping of first permanent molars in 25%, while no case of antagonist over-eruption was reported. CONCLUSIONS: When the permanent tooth is present and the ankylosed tooth is slightly or moderately infra-occluded, observation is appropriate. In case of severe infra-occlusion or absence of successor, tooth extraction may be considered together with orthodontic space closure, transplantation, or prosthetic replacement. Alternatively, nonextraction and a prosthetic build-up may be considered.