Facial electromyogram-based facial gesture recognition for hands-free control of an AR/VR environment: optimal gesture set selection and validation of feasibility as an assistive technology.

The rapid expansion of virtual reality (VR) and augmented reality (AR) into various applications has increased the demand for hands-free input interfaces when traditional control methods are inapplicable (e.g., for paralyzed individuals who cannot move their hands). Facial electromyogram (fEMG), bioelectric signals generated from facial muscles, could solve this problem. Discriminating facial gestures using fEMG is possible because fEMG signals vary with these gestures. Thus, these signals can be used to generate discrete hands-free control commands. This study implemented an fEMG-based facial gesture recognition system for generating discrete commands to control an AR or VR environment. The fEMG signals around the eyes were recorded, assuming that the fEMG electrodes were embedded into the VR head-mounted display (HMD). Sixteen discrete facial gestures were classified using linear discriminant analysis (LDA) with Riemannian geometry features. Because the fEMG electrodes were far from the facial muscles associated with the facial gestures, some similar facial gestures were indistinguishable from each other. Therefore, this study determined the best facial gesture combinations with the highest classification accuracy for 3-15 commands. An analysis of the fEMG data acquired from 15 participants showed that the optimal facial gesture combinations increased the accuracy by 4.7%p compared with randomly selected facial gesture combinations. Moreover, this study is the first to investigate the feasibility of implementing a subject-independent facial gesture recognition system that does not require individual user training sessions. Lastly, our online hands-free control system was successfully applied to a media player to demonstrate the applicability of the proposed system. Supplementary Information: The online version contains supplementary material available at 10.1007/s13534-023-00277-9.

Antimicrobial efficacy of self-locomotive manganese oxide nanozyme-doped diatom microbubbler on orthodontic brackets in vitro.

BACKGROUND: Orthodontic brackets provide a favorable environment for Streptococcus mutans biofilm formation, increasing the risk of white spots and dental caries. Manganese oxide (MnO2) nanozyme-doped diatom microbubbler (DM) is a recently developed material for biofilm removal. DM can generate oxygen by catalase-mimicking activity in Hydrogen peroxide (H2O2) solution and move with ejecting oxygen microbubbles to produce a mechanical self-cleansing effect. This study aimed to evaluate the feasibility of DM as a novel bracket cleaner. METHODS: DM was prepared according to the protocol and analyzed using a scanning electron microscope (SEM). We treated S. mutans biofilms grown over bracket with phosphate-buffered saline (PBS group), 0.12% chlorhexidine (CHX group), 3% H2O2 (H2O2 group), and co-treatment with 3 mg/mL of DM and 3% H2O2 (DM group). The biofilm removal effect was analyzed using crystal violet assay, and the results were observed using SEM. The viability of S. mutans in remaining biofilms was evaluated using confocal laser scanning microscopy (CLSM). Finally, we examined the effect of all materials on mature multispecies biofilms formed on debonded brackets. RESULTS: Crystal violet assay results revealed that the CHX group removed more biofilms than the control group, and the DM group removed biofilms more effectively than the CHX group (p < 0.0001). SEM and CLSM images showed that CHX killed S. mutans but failed to remove most biofilms on brackets. However, DM effectively removed biofilms and mature multispecies biofilms on debonded brackets (p < 0.0001). CONCLUSIONS: Co-treatment with DM and H2O2 is effective in removing biofilms on orthodontic brackets compared to conventional antibacterial agents.

In situ immobilization of YVO4:Eu phosphor particles on a film of vertically oriented Y2(OH)5Cl·nH2O nanosheets.

A heterostructured photoluminescence 'turn-off' film was developed using vertically oriented LYH:Eu nanosheets as a partial sacrificial layer for isolated YVO4:Eu3+ nanophosphor layers and was used for the convenient detection and removal of Cu2+ ions with excellent sensitivity and recyclability.

Luminescent Carrier, Tb3+-Doped Layered Yttrium Hydroxide, for Delivery Systems.

Layered rare-earth hydroxides (LRHs) with high anion exchangeability between the hydroxocation layers, where a large variety of organic anions can be sheltered, are employed to construct hybrid systems that slowly release active organic ingredients. More importantly, it is possible to endow LRHs with a photoluminescence capability by doping activator ions such as Ce3+, Eu3+, and Tb3+ into matrices. In the present work, we explored Tb3+-doped layered yttrium hydroxide Y1.80Tb0.20(OH)5Cl· nH2O (LYH:Tb) nanosheets as a luminescent carrier for sustained release of salicylic acid (2-hydroxybenzoic acid), an example of nonsteroidal anti-inflammatory drugs and antimicrobial agents. Salicylate (sal) was intercalated into the interlayer gallery of LYH:Tb via a direct ion-exchange reaction. An observed variation in basal spacing suggested that salicylate anions are arranged in an interdigitated bilayer manner in the interlayer space of LYH:Tb. As generally observed in organic/inorganic hybrid systems, the thermal and photostabilities of salicylate were significantly improved after intercalation compared to its free state. The release kinetics of salicylate from sal-LYH:Tb hybrids in a saline solution at pH = 7.4 showed a highly sustained release of salicylate. Among various examined mathematical models, the parabolic diffusion equation best described the cumulative salicylate release. In particular, the salicylate intercalation led to the characteristic 5D4 → 7F J ( J = 6, 5, and 4) green emission of Tb3+ by its sensitization followed by the energy transfer to sal-LYH:Tb, whereas typical blue emission of salicylate was recovered after its release from the interlayer gallery of the LYH:Tb carrier. This green/blue luminescence change behavior provides a useful technique for in situ monitoring of the delivery and release of salicylate at target sites. The sal-LYH:Tb hybrid, with antimicrobial properties, was readily dispersed into a biodegradable polymer, polyvinyl alcohol, to prepare a transparent, UV-shielding, and luminescent composite that is applicable as an antimicrobial polymer to retard or prevent microbial growth.

Layered Yttrium Hydroxide l-Y(OH)3 Luminescent Adsorbent for Detection and Recovery of Phosphate from Water over a Wide pH Range.

Layered yttrium hydroxide, l-Y(OH)3, has been explored as a representative member of the layered rare earth hydroxide family (l-RE(OH)3; RE = rare earths) for removal and recovery of phosphate from aqueous solution. Compared to the hexagonal form, h-Y(OH)3, which has a weakly positive surface charge only at low pH, the layered polymorph composed of hydroxocation layers exhibited a high point of zero charge (pHpzc ∼ 11) and significantly enhanced adsorptive ability for anions over a wide pH range. The Langmuir isotherm model and pseudo-second-order kinetic model were adopted to explain the phosphate adsorption on l-Y(OH)3. This new adsorbent revealed high capacity, efficiency, stability, selectivity, and reusability in adsorption of phosphate from a single electrolyte as well as natural waters containing competing anions. Essentially complete phosphate recovery from aqueous solutions at low phosphate concentrations (2.0 mg of P/L) was demonstrated with an adsorbent dosage of 0.025-0.5 g/L. The adsorption of phosphate was accompanied by an increase in the solution pH, suggesting a release of OH- ions during the adsorption reaction. In particular, when Ce3+ and Tb3+ were co-doped (l-Y(OH)3:Ce,Tb), phosphate adsorption led to the characteristic 5D4 → 7FJ (J = 6, 5, and 4) emissions of Tb3+ under commercial 312 nm UV irradiation. The photoluminescence of phosphate-adsorbed l-Y(OH)3:Ce,Tb provided evidence of the inner-sphere complexing mechanism involving the formation of Y(Ce,Tb)-O-P bonds through which the energy transfer can occur. The "luminescence-on" behavior of l-Y(OH)3:Ce,Tb by phosphate adsorption was employed to detect and recover phosphorus at low concentrations in deionized water, mineral water, tap water, and river water.

Selective Filter Effect Induced by Cu(2+) Adsorption on the Fluorescence of a GdVO4:Eu Nanoprobe.

Human blood contains substantial amounts of metal ions such as Mg(2+), Ca(2+), Fe(2+), Cu(2+), Zn(2+), Cd(2+), Pb(2+), and Al(3+). Most biomedical applications of nanoparticles require understanding the influence of these metal ions because adsorbed metal ions can affect the function of nanoparticles to limit their sensitivity, performance, stability, and/or resolution in applications. In the present work, the adsorption of various metal ions at the surface of GdVO4:Eu nanoparticles was studied to assess their spectral filter effect on the fluorescence of GdVO4:Eu. Due to the negative surface potential, the electrostatic attraction caused an intensive adsorption reaction of GdVO4:Eu nanoparticles with metal cations. Compared to the adsorption of other common metal ions in human blood, the distinct fluorescence quenching of GdVO4:Eu was induced in the presence of Cu(2+) ions. On the basis of the UV-vis absorption spectrum of an aqueous CuCl2 solution and reflectance spectrum of Cu(OH)2, in which the surroundings of Cu(2+) ions are supposedly similar to the hydroxylated surface of GdVO4:Eu nanoparticles, it is proposed that the complementary overlap of the emission band of GdVO4:Eu with the absorption band of Cu(2+) results in the effective filter effect to quench the red emission. Because GdVO4:Eu nanoparticles are attractive candidates for applications as magnetic/fluorescent multimodal nanoprobes, it is important to recognize that the average amount of Cu(2+) ion in human blood is sufficient to interfere with or limit the fluorescence probe function of GdVO4:Eu nanoparticles.

The inner filter effect of Cr(VI) on Tb-doped layered rare earth hydroxychlorides: new fluorescent adsorbents for the simple detection of Cr(VI).

Terbium-doped layered yttrium hydroxychlorides (LYH:xTb) were explored for the simple and convenient detection of Cr(VI) in aqueous solution, where the effective overlap of excitation bands of LYH:xTb with absorption bands of Cr(VI) constructs a new inner filter effect system. The shielding of excitation light for LYH:xTb by adsorbed Cr(VI) was so effective that a feasible detection sensitivity could be achieved.

Effect of long-term resistance exercise on body composition, blood lipid factors, and vascular compliance in the hypertensive elderly men.

Hypertension is designated as either essential (primary) hypertension or secondary hypertension and is defined as a consistently elevated blood pressure exceeding 140/90 mmHg. Hypertension is called "the silent killer" because it often causes no symptoms for many years, even decades, until it finally damages certain critical organs. In various causes of hypertension, obesity is an increasing health problem worldwide, and several epidemiological studies have identified a positive association between obesity and an increased incidence of hypertension. Therefore, in the present study, we investigated the effect of long-term resistance exercise on body composition, blood lipid profile, vascular compliance, and blood pressure in the elderly men. For this study, the In-Body test, blood lipid profile, and analysis of vascular compliance and blood pressure were performing before and after in experiment. The twenty male subjects aged between 68 and 72 yr were recruited from the 'Y' senior towers in Korea. All subjects performed exercises on a weight training machines 40 min once a day for 52 weeks. The exercise intensity for resistance training was 60% of the 10 RM maximal voluntary contraction test. All subjects before performing resistance exercise showed an increase in hypertension following enhanced %fat, blood lipid factors (TC, LDL-C), whereas decreased lean body mass (LBM), vascular compliance. However, 52 weeks of resistance exercise suppressed %fat and LDL-C, whereas improved LBM, vascular compliance, resulting in reducing hypertensive levels in the elderly men. We suggest that resistance exercise can be a valuable tool for the remarkable improvement of hypertension.