Development of an advanced velocity modulator for a portable Mössbauer spectrometer.

Mössbauer spectroscopy is a nuclear spectroscopic technique that measures changes in energy on an atomic scale. In a Mössbauer spectrometer, a velocity modulator oscillates a radioactive source to vary the energy of gamma rays. Conventional velocity modulators use wires primarily as motion guides; however, the tension state of these wires may change over time. Membrane springs are thus used as an alternative to wires; however, they also present certain challenges related to their design, manufacturing, and assembly. Instead of wires or membrane springs, this study used a linear bearing with preloaded compression springs. The advantage of this mechanism is that permanent deformation or changes in spring stiffness minimally occur during spring assembly and operation. The developed velocity modulator is compact and light, making it ideal for portable applications. A digital controller is used to easily modify and customize control parameters and the supporting algorithm, which is not easily achieved with conventional analog controllers. Moreover, by applying a switching amplifier, low-power operation is also achieved. Feedforward control values are calculated by an iterative learning method that is robust to the control of repeated motion. Using finite element method simulations and experiments, the performance of the developed prototype was evaluated. The velocity signal demonstrated linearity with a correlation with a straight line of approximately 0.996 for a triangular velocity profile (satisfactory performance).

Comparative study of 360° virtual reality and traditional two-dimensional video in nonface-to-face dental radiology classes: focusing on learning satisfaction and self-efficacy.

BACKGROUND: Acquiring adequate theoretical knowledge in the field of dental radiography (DR) is essential for establishing a good foundation at the prepractical stage. Currently, nonface-to-face DR education predominantly relies on two-dimensional (2D) videos, highlighting the need for developing educational resources that address the inherent limitations of this method. We developed a virtual reality (VR) learning medium using 360° video with a prefabricated head-mounted display (pHMD) for nonface-to-face DR learning and compared it with a 2D video medium. METHODS: Forty-four participants were randomly assigned to a control group (n = 23; 2D video) and an experimental group (n = 21; 360° VR). DR was re-enacted by the operator and recorded using 360° video. A survey was performed to assess learning satisfaction and self-efficacy. The nonparametric statistical tests comparing the groups were conducted using SPSS statistical analysis software. RESULTS: Learners in the experimental group could experience VR for DR by attaching their smartphones to the pHMD. The 360° VR video with pHMD provided a step-by-step guide for DR learning from the point of view of an operator as VR. Learning satisfaction and self-efficacy were statistically significantly higher in the experimental group than the control group (p < 0.001). CONCLUSIONS: The 360° VR videos were associated with greater learning satisfaction and self-efficacy than conventional 2D videos. However, these findings do not necessarily substantiate the educational effects of this medium, but instead suggest that it may be considered a suitable alternative for DR education in a nonface-to-face environment. However, further examination of the extent of DR knowledge gained in a nonface-to-face setting is warranted. Future research should aim to develop simulation tools based on 3D objects and also explore additional uses of 360° VR videos as prepractical learning mediums.

Mobile educational tool based on augmented reality technology for tooth carving: results of a prospective cohort study.

BACKGROUND: Augmented reality (AR) technology has been shown to be effective in displaying information and presenting three-dimensional objects. Although AR applications are commonly used by learners via mobile devices, plastic models or two-dimensional images are still commonly used in tooth carving practice. Learners practicing tooth carving face a challenge due to the three-dimensional features of teeth as there is a lack of tools available that provide sequential guidance. In this study, we developed an AR-based tooth carving practice tool (AR-TCPT) and compared it to a plastic model to evaluate its potential as a practice tool as well as its user experience. METHODS: To model tooth carving, we created a three-dimensional object from sequential steps that included the maxillary canines and maxillary first premolars (16 steps), mandibular first premolars (13 steps), and mandibular first molars (14 steps). Image markers, created using Photoshop software, were assigned to each tooth. An AR-based mobile application was developed using the Unity engine. For tooth carving, 52 participants were randomly assigned to a control group (n = 26; using a plastic tooth model) or an experimental group (n = 26; using the AR-TCPT). User experience was evaluated using a 22-item questionnaire. Data were comparatively analyzed using the nonparametric Mann-Whitney U test via the SPSS program. RESULTS: The AR-TCPT detects image markers with the mobile device camera and displays three-dimensional objects for tooth fragmentation. Users can manipulate the device to view each step or examine the shape of a tooth. The results of the user experience survey revealed that the AR-TCPT experimental group scored significantly higher in tooth carving experience compared with the control group that used the plastic model. CONCLUSION: Compared with the conventional plastic model, the AR-TCPT provided a better user experience for tooth carving. The tool is highly accessible as it is designed to be used on mobile devices by users. Further studies are required to determine the educational impact of the AR-TCTP on quantitative scoring of carved teeth as well as individual user's carving abilities.

Characterization of radiochromic films as a micrometer-resolution dosimeter by confocal Raman spectroscopy.

PURPOSE: Micrometer spatial resolution dosimetry has become inevitable for advanced radiotherapy techniques. A new approach using radiochromic films was developed to measure a radiation dose at a micrometer spatial resolution by confocal Raman spectroscopy. METHODS: The commercial radiochromic films (RCF), EBT3 and EBT-XD, were irradiated with known doses using 50, 100, 200, and 300 kVp, and 6-MV x rays. The dose levels ranged from 0.3 to 50 Gy. The Raman mapping technique developed in our early study was used to readout an area of 100 × 100 µm2 on RCF with improved lateral and depth resolutions with confocal Raman spectrometry. The variation in Raman spectra of C-C-C deformation and C≡C stretching modes of diacetylene polymers around 676 and 2060 cm-1 , respectively, as a function of therapeutic x-ray doses, was measured. The single peak (SP) of C≡C and the peak ratio (PR) of C≡C band height to C-C-C band height with a spatial resolution of 10 µm on both types of RCF were evaluated, averaged, and plotted as a function of dose. An achievable spatial resolution, clinically useful dose range, dosimetric sensitivity, dose uniformity, and postirradiation stability as well as the orientation, energy, and dose rate dependence, of both types of RCFs, were characterized by the technique developed in this study. RESULTS: A spatial resolution on RCF achieved by SP and PR methods was ~4.5 and ~2.9 µm, respectively. Raman spectroscopy data showed dose nonuniformity of ~11% in SP method and <3% in PR method. The SP method provided dose ranges of up to ~10 and ~20 Gy for EBT3 and EBT-XD films, respectively while the PR method up to ~30 and ~50 Gy. The PR method diminished the orientation effect. The percent difference between landscape and portrait orientations for the EBT3 and the EBT-XD films at 4 Gy had an acceptable level of 1.2% and 2.4%, respectively. With both SP and PR methods, the EBT3 and the EBT-XD films showed weak energy (within ~10% and ~3% for SP and PR methods, respectively) and dose rate dependence (within ~5% and ~3% for SP and PR methods, respectively) and had a stable response after 24-h postirradiation. CONCLUSIONS: A technique for micrometer-resolution dosimetry was successfully developed by detecting radiation-induced Raman shift on EBT3 and EBT-XD. Both types of RCFs were suitable for micrometer-resolution dosimetry using CRS. With CRS both lateral and depth resolutions on RCF were improved. The PR method provided superior characteristics in dose uniformity, dose ranges, orientation dependence, and laser effect for both types of RCFs. The overall dosimetric characteristics of the RCFs determined by this technique were similar to those known by optical density scanning. The CRS with the PR method is advantageous over other the traditional scanning systems as a spatial resolution of <10 µm on RCF can be achieved with less deviations.

Fano cavity test for electron Monte Carlo transport algorithms in magnetic fields: comparison between EGSnrc, PENELOPE, MCNP6 and Geant4.

A Fano cavity test was performed for four general-purpose Monte Carlo codes, EGSnrc, PENELOPE, MCNP6 and Geant4 to evaluate the accuracy of their electron transport algorithms in magnetic fields. In the simulations, a plane-parallel ionization chamber was modelled as a circular gas disk sandwiched between two circular solid wall disks. It was assumed that an isotropic and uniform line source per unit mass along the central axis of the gas and solid emits mono-energetic electrons with energies 0.01, 0.1, 1.0 and 3.0 MeV at different magnetic field strengths 0, 0.35, 1.0, 1.5 and 3.0 T in the electron transport mode (no Bremsstrahlung). The relative difference between the calculated dose to the gas region and the initial total energy of emitted electrons per unit mass was defined as the accuracy of Monte Carlo codes. In all results, EGSnrc with the enhanced electric and magnetic field (EEMF) macros was not considerably sensitive to the step size parameters and showed accuracy less than 0.18% ± 0.06% with a coverage factor k = 2. The other codes could not achieve competent accuracy with their default settings of step size parameters, compared to EGSnrc with the EEMF macros. With the step size parameters carefully selected, the accuracy of PENELOPE and MCNP6 was within 1.0% and 0.4%, respectively. However, Geant4 showed accuracy within 1.7% except in 3.0 T. EGSnrc with the EEMF macros achieved the best accuracy for the Fano test at the electron energies and the magnetic field strengths investigated in this study and thus, would be recommended to simulate dose responses of ionization chambers in the presence of magnetic fields.

Fluoroethylene Carbonate-Based Electrolyte with 1 M Sodium Bis(fluorosulfonyl)imide Enables High-Performance Sodium Metal Electrodes.

Sodium (Na) metal anodes with stable electrochemical cycling have attracted widespread attention because of their highest specific capacity and lowest potential among anode materials for Na batteries. The main challenges associated with Na metal anodes are dendritic formation and the low density of deposited Na during electrochemical plating. Here, we demonstrate a fluoroethylene carbonate (FEC)-based electrolyte with 1 M sodium bis(fluorosulfonyl)imide (NaFSI) salt for the stable and dense deposition of the Na metal during electrochemical cycling. The novel electrolyte combination developed here circumvents the dendritic Na deposition that is one of the primary concerns for battery safety and constructs the uniform ionic interlayer achieving highly reversible Na plating/stripping reactions. The FEC-NaFSI constructs the mechanically strong and ion-permeable interlayer containing NaF and ionic compounds such as Na2CO3 and sodium alkylcarbonates.

Abstract ID: 13 Monte Carlo simulations for the beam quality factors of a parallel-plate ion-chamber in the presence of magnetic field.

Magnetic resonance imaging-guided radiotherapy provides real-time imaging with a superior soft-tissue contrast without radiation exposure. Recently, several groups have been developing such a new technology. Strong magnetic fields can influence trajectories of the secondary electrons by the Lorentz force. The reference dosimetry using an ion-chamber in magnetic fields needs additional correction factors [1]. In this study, we calculated magnetic field correction factors by the Monte Carlo method for the reference dosimetry using a parallel-plate ion-chamber. The EGSnrc user code, egs_chamber was used to simulate an ion-chamber. The full head and spectral source models of Varian therapeutic linear accelerator of 6 MV, 10 MV, and 15 MV photon beam have been simulated by BEAMnrc and beamdp. A parallel-plate ion-chamber (NACP-02 model) was positioned in the water phantom (30 × 30 × 30 cm3) at a depth of 10 cm (5 cm for Co-60 beam). The beam quality factors (KQ) and magnetic field correction factors (KQ,B) were calculated. The absorbed dose of a parallel-plate ion-chamber was scored with and without a 1.5 T of magnetic field. The KQ of 6 MV, 10 MV, and 15 MV were 0.994, 0.980, and 0.976, respectively. These values were compatible to the previous published data (<0.3%) [2]. In a 1.5 T of magnetic field, the KQ,B of 6, 10, and 15 MV were 0.935, 0.985, and 0.994, respectively, compared to 0.975, 0.983, and 0.983 in a 0.35 T of magnetic field. All of simulation uncertainties were within 0.2%. When photon energy increases, KQ,B is also increased, but KQ,B in high strength of a magnetic field are not always smaller than those in low strength of a magnetic field. The magnetic field correction factors of a parallel-plate ion-chamber were successfully calculated by the Monte Carlo method. The parallel-plate ion-chambers need several percent of correction factors when measuring doses in the presence of a magnetic field.

Ultraconcentrated Sodium Bis(fluorosulfonyl)imide-Based Electrolytes for High-Performance Sodium Metal Batteries.

We present an ultraconcentrated electrolyte composed of 5 M sodium bis(fluorosulfonyl)imide in 1,2-dimethoxyethane for Na metal anodes coupled with high-voltage cathodes. Using this electrolyte, a very high Coulombic efficiency of 99.3% at the 120th cycle for Na plating/stripping is obtained in Na/stainless steel (SS) cells with highly reduced corrosivity toward Na metal and high oxidation durability (over 4.9 V versus Na/Na+) without corrosion of the aluminum cathode current collector. Importantly, the use of this ultraconcentrated electrolyte results in substantially improved rate capability in Na/SS cells and excellent cycling performance in Na/Na symmetric cells without the increase of polarization. Moreover, this ultraconcentrated electrolyte exhibits good compatibility with high-voltage Na4Fe3(PO4)2(P2O7) and Na0.7(Fe0.5Mn0.5)O2 cathodes charged to high voltages (>4.2 V versus Na/Na+), resulting in outstanding cycling stability (high reversible capacity of 109 mAh g-1 over 300 cycles for the Na/Na4Fe3(PO4)2(P2O7) cell) compared with the conventional dilute electrolyte, 1 M NaPF6 in ethylene carbonate/propylene carbonate (5/5, v/v).

Design and evaluation of electron beam energy degraders for breast boost irradiation.

BACKGROUND: For breast cancer patients who require electron boost energies between 6 and 9 MeV, an energy degraders (ED) in the 9 MeV beamline was specially designed and manufactured to increase the skin dose of 6 MeV and to reduce the penetration depth of 9 MeV beams. METHODS: We used Monte Carlo (MC) techniques as a guide in the design of ED for use with linear accelerators. In order to satisfy percent depth dose (PDD) characteristics and dose profile uniformity in water, the shape and thickness of Lucite® ED in the 9 MeV beamline was iteratively optimized and then manufactured. The ED geometry consists of a truncated cone attached on top of a plane plate, with total central thickness of 1.0 cm. The ED was placed on the lower most scraper of the electron applicator. The PDDs, profiles, and output factors were measured in water to validate the MC-based design. RESULTS: Skin doses with the EDs increased by 8-9 %, compared to those of the 9 MeV beam. The outputs with the EDs were 0.882 and 0.972 for 10 × 10 and 15 × 15 cm(2) cones, respectively, as compared to that of a conventional 9 MeV beam for a 10 × 10 cm(2) cone. The X-ray contamination remained less than 1.5 %. In-vivo measurements were also performed for three breast boost patients and showed close agreement with expected values. CONCLUSIONS: The optimally designed ED in the 9 MeV beamline provides breast conserving patients with a new energy option of 7 MeV for boost of the shallow tumor bed. It would be an alternative to bolus and thus eliminate inconvenience and concern about the daily variation of bolus setup.

Inclined head position improves dose distribution during hippocampal-sparing whole brain radiotherapy using VMAT.

PURPOSE: Hippocampal-sparing whole brain radiotherapy (HS-WBRT) aims to preserve neurocognitive functions in patients undergoing brain radiotherapy (RT). Volumetric modulated arc therapy (VMAT) involves intensity-modulated RT using a coplanar arc. An inclined head position might improve dose distribution during HS-WBRT using VMAT. MATERIALS AND METHODS: This study analyzed 8 patients receiving brain RT with inclined head positioning. A comparable set of CT images simulating a non-inclined head position was obtained by rotating the original CT set. HS-WBRT plans of coplanar VMAT for each CT set were generated with a prescribed dose of 30 Gy in 10 fractions. Maximum dose to the hippocampi was limited to 16 Gy; to the optic nerve, optic chiasm, and eyeballs this was confined to less than 37.5 Gy; for the lenses to 8 Gy. Dosimetric parameters of the two different plans of 8 patients were compared with paired t-test. RESULTS: Mean inclined head angle was 11.09 ± 0.73°. The homogeneity (HI) and conformity (CI) indexes demonstrated improved results, with an average 8.4 ± 10.0 % (p = 0.041) and 5.3 ± 3.9 % (p = 0.005) reduction, respectively, in the inclined vs. non-inclined position. The inclined head position had lower hippocampi Dmin (10.45 ± 0.36 Gy), Dmax (13.70 ± 0.25 Gy), and Dmean (12.01 ± 0.38 Gy) values vs. the non-inclined head position (Dmin = 12.07 ± 1.07 Gy; Dmax = 15.70 ± 1.25 Gy; Dmean = 13.91 ± 1.01 Gy), with 12.8 ± 8.9 % (p = 0.007), 12.2 ± 6.8 % (p = 0.003), and 13.2 ± 7.2 % (p = 0.002) reductions, respectively. Mean Dmax for the lenses was 6.34 ± 0.72 Gy and 7.60 ± 0.46 Gy, respectively, with a 16.3 ± 10.8 % reduction in the inclined position (p = 0.004). Dmax for the optic nerve and Dmean for the eyeballs also decreased by 7.0 ± 5.9 % (p = 0.015) and 8.4 ± 7.2 % (p = 0.015), respectively. CONCLUSION: Inclining the head position to approximately 11° during HS-WBRT using VMAT improved dose distribution in the planning target volume and allowed lower doses to the hippocampi and optic apparatus.

Volumetric modulated arc therapy for carotid sparing in the management of early glottic cancer.

PURPOSE: Radiotherapy of the neck is known to cause carotid artery stenosis. We compared the carotid artery dose received between volumetric modulated arc therapy (VMAT) and conventional fixed-field intensity-modulated radiotherapy (IMRT) plans in patients with early glottic cancer. MATERIALS AND METHODS: Twenty-one early glottic cancer patients who previously underwent definitive radiotherapy were selected for this study. For each patient, double arc VMAT, 8-field IMRT, 3-dimensional conformal radiotherapy (3DCRT), and lateral parallel-opposed photon field radiotherapy (LPRT) plans were created. The 3DCRT plan was generated using lateral parallel-opposed photon fields plus an anterior photon field. VMAT and IMRT treatment plan optimization was performed under standardized conditions to obtain adequate target volume coverage and spare the carotid artery. Dose-volume specifications for the VMAT, IMRT, 3DCRT, and LPRT plans were calculated with radiotherapy planning system. Monitor units (MUs) and delivery time were measured to evaluate treatment efficiency. RESULTS: Target volume coverage and homogeneity results were comparable between VMAT and IMRT; however, VMAT was superior to IMRT for carotid artery dose sparing. The mean dose to the carotid arteries in double arc VMAT was reduced by 6.8% compared to fixed-field IMRT (p < 0.001). The MUs for VMAT and IMRT were not significantly different (p = 0.089). VMAT allowed an approximately two-fold reduction in treatment delivery time in comparison to IMRT (3 to 5 minutes vs. 5 to 10 minutes). CONCLUSION: VMAT resulted in a lower carotid artery dose compared to conventional fixed-field IMRT, and maintained good target coverage in patients with early glottic cancer.

Characterizing the Lateral Border of the Frontalis for Safe and Effective Injection of Botulinum Toxin.

BACKGROUND: The forehead is a common site for injection of botulinum neurotoxin type A (BoNT-A) to treat hyperactive facial muscles. Unexpected side effects of BoNT-A injection may occur because the anatomy of the forehead musculature is not fully characterized. OBJECTIVES: The authors described the lateral border of the frontalis in terms of facial landmarks and reference lines to determine the safest and most effective forehead injection sites for BoNT-A. METHODS: The hemifaces of 49 embalmed adult Korean cadavers were dissected in a morphometric analysis of the frontalis. L2 was defined in terms of FT (the most protruding point of the frontotemporal region), L0 (the line connecting the infraorbital margin with the tragus), and L1 (the line parallel to L0 and passing through FT) such that L2 was positioned 45° from L1 and passed through FT. RESULTS: The distance from FT to the superior margin of the orbicularis oculi was 12.3 ± 3.3 mm. The frontalis extended more than 5 cm along L2 in 49 of 49 cases (100%), more than 6 cm in 47 cases (95.9%), more than 7 cm in 34 cases (69.4%), more than 8 cm in 11 cases (22.4%), and more than 9 cm in 3 cases (6.1%). The lateral border of the frontalis ran parallel to and within 1 cm of the medial side of L2. CONCLUSIONS: Surface anatomy mapping can assist with predicting the lateral border of the frontalis to minimize the side effects and maximize the efficiency of BoNT-A injections into the forehead.

The effect of body contouring on the dose distribution delivered with volumetric-modulated arc therapy technique.

The purpose of the study was to investigate the dosimetric effect defining the body structure with various Hounsfield unit (HU) threshold values on the dose distributions of volumetric-modulated arc therapy (VMAT) plans. Twenty patients with prostate cancer and twenty patients with head and neck (H&N) cancer were retrospectively selected. For each patient, the body structure was redefined with HU threshold values of -180 (Body180), -350 (Body350), -700 (Body700), and -980 (Body980). For each patient, dose-volumetric parameters with those body structures were calculated using identical VMAT plans. The differences in dose-volumetric parameters due to the varied HU threshold values were calculated. For the prostate boost target volume, the maximum dose, mean dose, D95%, and D5% with Body180 were higher than those with Body980 by approximately 0.7% (p < 0.001). For H&N target volumes, the changes in D95% of the targets receiving 67.5 Gy, 54 Gy, and 48 Gy between Body180 and Body980 were -1.2%, -0.9%, and -1.2%, respectively (p < 0.001). The differences were larger for H&N VMAT plans than for prostate VMAT plans due to the inclusion of an immobilization device in the irradiated region in H&N cases. To apply all attenuating materials to dose calculation, the body structure would be defined with -980 HU. Otherwise, systematic error of about 1%, resulting in underdosage of the target volume, can occur.

Dosimetric effects of roll rotational setup errors on lung stereotactic ablative radiotherapy using volumetric modulated arc therapy.

OBJECTIVE: To evaluate the dosimetric effects of roll-rotational setup errors of stereotactic ablative radiotherapy (SABR) for lung cancer using volumetric modulated arc therapy (VMAT). METHODS: A total of 23 lung SABR cases were evaluated retrospectively. Each of the planning CT images was intentionally rotated by ±1°, ±2° and ±3°. After that, to simulate the translational couch correction, rotated CT images were moved along the x, y and z axis to match the centroid of the target volume in the rotated CT images with that in the original CT images. The differences in D95% and V100% of the target volume, D0.35cc of spinal cord, D0.35cc and D5cc of oesophagus and V20Gy of lung between the original and the rotated CT images were calculated. RESULTS: The average differences in D95% and V100% of target volume, D0.35cc of spinal cord, D0.35cc and D5cc of oesophagus and V20Gy of lung were -0.3% ± 0.4% and -0.7% ± 2.4%, 1.6 ± 27.9 cGy, -1.6 ± 37.6 cGy, 15.9 ± 25.3 cGy and 0.0% ± 0.1%, respectively. The dosimetric changes in organs at risk (OARs) near the target volume were sometimes considerable due to roll-rotational setup errors, despite the translational correction, and those were patient specific. CONCLUSION: In the case of coplanar VMAT for lung SABR, dosimetric changes to the target volume due to roll-rotational setup errors could be compensated by translational correction, whereas those to the OARs could not in some cases. ADVANCES IN KNOWLEDGE: Roll-rotational setup errors would increase the dose to OARs despite the translational correction.

Quantitative anatomical analysis of facial expression using a 3D motion capture system: Application to cosmetic surgery and facial recognition technology.

The topography of the facial muscles differs between males and females and among individuals of the same gender. To explain the unique expressions that people can make, it is important to define the shapes of the muscle, their associations with the skin, and their relative functions. Three-dimensional (3D) motion-capture analysis, often used to study facial expression, was used in this study to identify characteristic skin movements in males and females when they made six representative basic expressions. The movements of 44 reflective markers (RMs) positioned on anatomical landmarks were measured. Their mean displacement was large in males [ranging from 14.31 mm (fear) to 41.15 mm (anger)], and 3.35-4.76 mm smaller in females [ranging from 9.55 mm (fear) to 37.80 mm (anger)]. The percentages of RMs involved in the ten highest mean maximum displacement values in making at least one expression were 47.6% in males and 61.9% in females. The movements of the RMs were larger in males than females but were more limited. Expanding our understanding of facial expression requires morphological studies of facial muscles and studies of related complex functionality. Conducting these together with quantitative analyses, as in the present study, will yield data valuable for medicine, dentistry, and engineering, for example, for surgical operations on facial regions, software for predicting changes in facial features and expressions after corrective surgery, and the development of face-mimicking robots.

Tunable and robust phosphite-derived surface film to protect lithium-rich cathodes in lithium-ion batteries.

A thin, uniform, and highly stable protective layer tailored using tris(trimethylsilyl) phosphite (TMSP) with a high tendency to donate electrons is formed on the Li-rich layered cathode, Li1.17Ni0.17Mn0.5Co0.17O2. This approach inhibits severe electrolyte decomposition at high operating voltages during cycling and dramatically improves the interfacial stability of the cathode. The TMSP additive in the LiPF6-based electrolyte is found to preferentially eliminate HF, which promotes the dissolution of metal ions from the cathode. Our investigation revealed that the TMSP-derived surface layer can overcome the significant capacity fading of the Li-rich cathode by structural instability ascribed to an irreversible phase transformation from layered to spinel-like structures. Moreover, the superior rate capability of the Li-rich cathode is achieved because the TMSP-originated surface layer allows facile charge transport at high C rates for the lithiation process.

Facial arterial depth and relationship with the facial musculature layer.

BACKGROUND: Previous studies have revealed a variation in the origin and distribution patterns of the facial artery. However, the relationship between the facial artery and the facial muscles has not been well described. The purpose of this study was to determine the facial artery depth and relationship with the facial musculature layer, which represents critical information for dermal filler injection and oral and maxillofacial surgery. METHODS: Fifty-four embalmed adult faces from Korean cadavers (36 male and 18 female cadavers; mean age, 73.3 years) were used in this study. A detailed dissection was performed, with great care being taken to avoid damaging the facial artery underlying the facial skin and muscle. RESULTS: The facial artery was first categorized according to the patterns of its final arterial branches. The branching pattern was classified simply into three types: type I, nasolabial pattern (51.8 percent); type II, nasolabial pattern with an infraorbital trunk (29.6 percent); and type III, forehead pattern (18.6 percent). Each type was further subdivided according to the facial artery depth and relationship with the facial musculature layer as types Ia (37.0 percent), Ib (14.8 percent), IIa (16.7 percent), IIb (12.9 percent), IIIa (16.7 percent), and IIIb (1.9 percent). CONCLUSION: This study provides new anatomical insight into the relationships between the facial artery branches and the facial muscles, including providing useful information for clinical applications in the fields of oral and maxillofacial surgery.

Frontal branch of the superficial temporal artery: anatomical study and clinical implications regarding injectable treatments.

BACKGROUND: The frontal branch of the superficial temporal artery (Fbr) is vulnerable to damage triggered by iatrogenic manipulation by both dermal filler and BoNT-A injection. The purpose of this study was to elucidate the branching pattern of Fbr and to determine its location and course on the lateral border of the frontal belly of the occipitofrontalis muscle (FB). METHODS: Sixty-four hemifaces from 38 Korean cadavers (26 males and 12 females; mean age 71.9 years) were dissected, and the location and course of the Fbr were identified with reference to the lateral border of the FB. RESULTS: The ramification of the frontal branch from the superficial temporal artery (STA) occurred 36.9 ± 14.24 mm (mean ± SD) superior and 17.2 ± 8.2 mm anterior to the posterior-most point of the tragus [i.e., tragion (Tg)]. The Fbr was observed as a single branch in 96.9% of cases and reached its destination at a single point in 71.9%. It reached the Fbr 14.8 ± 7.7 mm superior to the uppermost point of the eyebrow and 15.8 ± 9.1 mm from the lateral epicanthus. The Fbr bifurcated into superior and inferior branches before reaching the FB in 25.0% of cases. In two cases (3%), the Fbr ramified from the STA within 1 mm of the Tg. The diameter of the superior division of Fbr was 1.6 ± 0.5 mm at the lateral border of the FB and 1.8 ± 0.6 mm at other locations. CONCLUSION: Physicians performing injection treatments such as botulinum toxin type A and dermal filler injection to the posterior frontal area should be aware of the various distributions of the Fbr.

The risorius muscle: anatomic considerations with reference to botulinum neurotoxin injection for masseteric hypertrophy.

BACKGROUND: The botulinum neurotoxin Type A (BTX) injection into the masseter muscle often causes a change in the facial expression. There is as yet no precise anatomic evidence to support this etiologic factor of constrained facial expressions. OBJECTIVE: The aim of this study was to clarify the location and boundaries of the risorius muscle and its topographical relationship with the surrounding structures. MATERIALS AND METHODS: This study involved the dissection of 48 hemifaces. The locations of origin and insertion points of the risorius muscle were measured, and the masseter muscle was divided into 6 equally sized rectangular areas. RESULTS: Cases where the masseter muscle was covered by the risorius muscle were classified into the following 4 types: in Type A, Area III was partially covered by the risorius (17.8%); in Type B, Area VI was partially covered (20.0%); in Type C, Areas III and VI were partially covered (53.3%); and in Type D, Areas II, III, and VI were covered (6.7%). CONCLUSION: These findings suggest that the medial part of the masseter muscle represents a hazard zone into which the injection of BTX may affect the risorius muscle, potentially resulting in iatrogenic unnatural facial expressions.