Performance evaluation of a wrist-worn reflectance pulse oximeter during sleep.

OBJECTIVES: To characterize and evaluate the estimation of oxygen saturation measured by a wrist-worn reflectance pulse oximeter during sleep. METHODS: Ninety-seven adults with sleep disturbances were enrolled. Oxygen saturation was simultaneously measured using a reflectance pulse oximeter (Galaxy Watch 4 [GW4], Samsung, South Korea) and a transmittance pulse oximeter (polysomnography) as a reference. The performance of the device was evaluated using the root mean squared error (RMSE) and coverage rate. Additionally, GW4-derived oxygen desaturation index (ODI) was compared with the apnea-hypopnea index (AHI) derived from polysomnography. RESULTS: The GW4 had an overall RMSE of 2.3% and negligible bias of -0.2%. A Bland-Altman density plot showed good agreement between the GW4 and the reference pulse oximeter. RMSEs were 1.65 ± 0.57%, 1.76 ± 0.65%, 1.93 ± 0.54%, and 2.93 ± 1.71% for normal (n = 18), mild (n = 21), moderate (n = 23), and severe obstructive sleep apnea (n = 35), respectively. The data rejection rate was 26.5%, which was caused by fluctuations in contact pressure and the discarding of data less than 70% of saturation. A GW4-ODI ≥5/h had the highest ability to predict AHI ≥15/h with sensitivity, specificity, accuracy, and area under the curve of 89.7%, 64.1%, 79.4%, and 0.908, respectively. CONCLUSIONS: This study evaluated the estimation of oxygen saturation by the GW4 during sleep. This device complies with both Food and Drug Administration and International Organization for Standardization standards. Further improvements in the algorithms of wearable devices are required to obtain more accurate and reliable information about oxygen saturation measurements.

[Effects of stress, depression, and spousal and familial support on maternal identity in pregnant women]. / 임부의 ìŠ¤íŠ¸ë ˆìŠ¤, 우울 및 배우자와 가족의 지지가 모성 ì •ì²´ì„±ì— 미치는 영향.

Purpose: The objective of this study was to identify the factors influencing maternal identity in pregnant women. Methods: Using a descriptive research design, a cross-sectional survey was conducted. In total, 127 pregnant women were recruited from a tertiary hospital in Korea from January to April 2019. Measurements included maternal identity, stress, depression, spousal and familial support, and demographic and obstetric characteristics. Data were analyzed by descriptive statistics, the independent t-test, one-way ANOVA, Pearson correlation coefficients, and stepwise multiple regression using SPSS version 25.0. Results: The mean score for maternal identity was 131.15 out of 160, and the mean scores for stress, depression, and spousal and familial support were 14.59 (out of 40), 6.82 (out of 30), and 109.04 (out of 132), respectively. Stress (r=-.38, p<.001), depression (r=-.37, p<.001), and spousal and familial support (r=.37, p<.001) were significantly correlated with maternal identity. In multiple regression analysis, stress (ß=-0.27, p=.005) and spousal and familial support (ß=0.23, p=.014) were found to be significant factors influencing maternal identity in pregnant women (F=14.19, p<.001). Conclusion: It is necessary to develop effective strategies to mitigate stress and to encourage spousal and familial support in pregnant women. Such strategies could further enable pregnant women to enhance their maternal identity.

Effects of trunk-hip strengthening on standing in children with spastic diplegia: a comparative pilot study.

[Purpose] This study evaluated the effects of trunk-hip strengthening exercise on trunk-hip activation and pelvic tilt motion during standing in children with spastic diplegia and compared the improvement of pelvic tilt between the modified trunk-hip strengthening exercise and conventional exercise. [Subjects and Methods] Ten ambulant children with spastic diplegia were randomized to the modified trunk-hip strengthening exercise (n = 5) or conventional exercise (n = 5) group. The intervention consisted of a 6-week modified trunk-hip strengthening exercise 3 times per week. The children were tested for trunk-hip muscles activation and pelvic tilt motion during standing by surface electromyography and an inclinometer before and after the intervention. [Results] The anterior pelvic tilt angle and activation of the extensor spinae, rectus femoris, and semitendinosus during standing decreased significantly in the modified exercise group. The activation of extensor spinae differed significantly between groups. [Conclusion] Compared to the conventional exercise, the modified exercise was more effective for trunk-hip activation improvement and anterior pelvic tilt motion decrease during standing in children with spastic diplegia. We suggest clinicians use an individually tailored modified trunk-hip strengthening exercise for strengthening the weakest muscle groups in children with standing ability problems.

Influence of pelvic position and vibration frequency on muscle activation during whole body vibration in quiet standing.

[Purpose] The purpose of this study was to investigate muscle activation related to postural stability depending on the pelvic position and frequency of whole body vibration (WBV) during quiet standing, and to identify the most effective training conditions that elicit the highest neuromuscular responses. [Subjects and Methods] Eighteen healthy subjects voluntarily participated in this single-group, repeated-measures study in which surface electromyography (EMG) data for the upper trapezius, rectus abdominis, external oblique abdominis, erector spinae, gluteus maximus, rectus femoris, semitendinosus, and medial gastrocnemius were collected at three frequencies (0 Hz, 10 Hz, and 20 Hz) of WBV and three pelvic positions (neutral, anterior tilt, posterior tilt) for each subject during quiet standing. [Results] The EMG activities of all the recorded muscles showed significant differences between the three frequencies of WBV and three pelvic positions during quiet standing. [Conclusion] The study findings suggest that a higher WBV frequency (20 Hz) should be used to strengthen most muscles, and that using the posterior pelvic tilt during WBV is much more effective at strengthening and training muscles related to core stability.

A centrifugally actuated point-of-care testing system for the surface acoustic wave immunosensing of cardiac troponin I.

A fully automated point-of-care testing (POCT) system with a surface acoustic wave (SAW) immunosensor was developed for rapid and sensitive detection of cardiac troponin I (cTnI) in body fluid (plasma and whole blood). The assay, based on gold nanoparticle sandwich immunoassay and subsequent gold staining, was performed on the SAW immunosensor packaged inside a disposable microfluidic cartridge. The entire fluidic process, including plasma separation, reagent transport, metering, and mixing, was carried out by controlling the centrifugal force acting on the rotating cartridge and laser-irradiated ferrowax microvalves. On investigation of sensor response to various cTnI concentrations, the system exhibited a high performance with a detection limit of 6.7 pg mL(-1), and the coefficient of variation was less than 10% over the entire test range (10 pg mL(-1) to 25 ng mL(-1)). On comparing this POCT system with a clinically utilized system in a physical laboratory (Centaur® XP; Siemens), a correlation coefficient of 0.998 was found, validating the diagnostic capability of the SAW immunosensor.

A rapid and facile signal enhancement method for microcantilever-based immunoassays using the agglomeration of ferromagnetic nanoparticles.

A rapid and facile signal enhancement method for detecting alpha-fetoprotein (AFP) was developed using the magnetic agglomeration of ferromagnetic nanoparticles and microcantilever sensors. The resonance frequency and deflection of the cantilevers were found to be more than 10-fold greater than that before physical agglomeration of the free nanoparticles around the magnetized nanoparticles.

A rapid and facile method for measuring corrosion rates using dynamic light scattering.

A dynamic light scattering (DLS) method was adopted for measuring the corrosion of iron nanoparticles. The average diameter of the nanoparticles in a sodium chloride suspension increased linearly with time as iron oxide layers formed around the nanoparticles. The nanoparticle corrosion rate determined by DLS was found to be almost identical to the value obtained by conventional immersion tests (ASTM G31). The DLS method offers the advantage that measurements may be completed within several hours under natural corrosion conditions whereas the conventional immersion method requires several months. Application of the DLS method to alloy nanoparticles with a variety of chromium compositions showed that the nanoparticle sizes changed nonlinearly over time, and the curves were best fit by a first order exponential function. The first order time constants were found to be linearly related to the corrosion rates determined by ASTM G31.

A visible light-induced photocatalytic silver enhancement reaction for gravimetric biosensors.

We have developed a novel microgravimetric immunosensor using a WO(3) nanoparticle-modified immunoassay and a silver enhancement reaction. When the nanoparticles in silver ion solution (i.e.  AgNO(3)) are exposed to visible light, the silver ions are photocatalytically reduced and form a metallic silver coating on the nanoparticles. This silver coating consequently induces changes in the mass and light absorption spectrum. Although photocatalytic reduction reactions can be achieved using ultraviolet (UV) light and TiO(2) nanoparticles as described in our previous publication (Seo et al 2010 Nanotechnology 21 505502), the use of UV light in biosensing applications has drawbacks in that UV light can damage proteins. In addition, conventional quartz crystal substrates must be passivated to prevent undesirable silver ion reduction on their gold-coated sensing surfaces. We addressed these problems by adopting a visible light-induced photocatalytic silver enhancement method using WO(3) nanoparticles and lateral field excited (LFE) quartz crystals. As a proof-of-concept demonstration of the technique, streptavidin was adsorbed onto an LFE quartz crystal, and its mass was enhanced with biotinylated WO(3) nanoparticles, this being followed by a photocatalytic silver enhancement reaction. The mass change due to the enhancement was found to be > 30 times greater than the mass change obtained with the streptavidin alone.

Photocatalytic silver enhancement reaction for gravimetric immunosensors.

A novel microgravimetric immunosensor has been developed using TiO(2) nanoparticle-modified immunoassay and silver enhancement reaction. An antibody-conjugated TiO(2) nanoparticle is bound to the AFP antigen immobilized on a quartz resonator. When the nanoparticles are exposed to UV light in a silver nitrate solution, the photocatalytic reduction of silver ions results in the formation of metallic silver onto the nanoparticles and induces a decrease in the resonance frequency. The frequency change by this photocatalytic reduction reaction is three orders of magnitude larger than the change by antigen binding alone. The efficiency of the photocatalytic reaction has been found to increase with the fraction of anatase crystallites in the nanoparticles and the concentration of the AgNO(3) solution. The results highlight the potential of the photocatalytic nanoparticles for the detection of low concentrations of target molecules using gravimetric sensors.

Enhanced photocatalytic activity of highly crystallized and ordered mesoporous titanium oxide measured by silicon resonators.

Ordered mesoporous TiO(2) was synthesized using the combined assembly of soft and hard chemistries method and deposited as a film coating on a microcantilever sensor array along with two other types of TiO(2) film: one from nanoparticles and one prepared via a sol-gel reaction. After loading methylene blue molecules on the TiO(2) films, the films were exposed to ultraviolet radiation. The photocatalytic decomposition of methylene blue was monitored by measuring changes in the resonance frequency of each cantilever. The mesoporous TiO(2) film showed higher photocatalytic activity than conventional TiO(2) films fabricated from nanoparticles or via a sol-gel reaction; this difference is attributed to the purely anatase crystalline morphology of the mesoporous TiO(2) film as well as its well-organized pore structure. The three-dimensionally interconnected pore network facilitates the diffusion of methylene blue molecules to the photocatalytically active sites of the mesoporous TiO(2).

Influence of nanobubbles on the adsorption of nanoparticles.

A quartz crystal microbalance was used to study the influence of nanobubbles on the adsorption of polystyrene nanoparticles onto surfaces coated with gold, or coated with dodecanethiol or mercaptoundecanoic acid self-assembled monolayers (SAMs). Adsorption of the nanoparticles onto the surface causes the resonant frequency of the quartz crystal to decrease. We found that particles were adsorbed onto the gold-coated quartz crystal in air-rich water, but not in degassed water. This finding supports the long-standing hypothesis that nanobubbles play a key role in the long-range attractive force between hydrophobic surfaces in aqueous solutions. When the experiments were conducted using quartz crystals coated with a hydrophobic dodecanethiol SAM, the nanoparticles were adsorbed onto the surface even in degassed water due to the short-range hydrophobic interactions between the nanoparticles and the dodecanethiol molecules. In contrast, the nanoparticles were adsorbed to a lesser degree onto the hydrophilic mercaptoundecanoic acid-coated crystals due to electrostatic repulsive forces.