Reliability analysis of inertial sensors for testing static balance of 4-to-5-year-old preschoolers.

BACKGROUND: Balance ability is important for preschoolers' motor and physical development. Portable accelerometers can provide resolution tests and identification of preschoolers with balance defects. RESEARCH QUESTION: Despite previous studies on the balance measures of accelerometer tests, there is a lack of complete analyses for preschoolers aged 4-5 years. In this study, we aim to verify the reliability of measuring the static balance of preschoolers in this age range based on inertia sensors for the acceleration and angular velocity moduli. METHODS: Thirty children wore an inertial sensor in the 5th lumbar vertebra and completed four tests, i.e., standing on a firm surface and on a foam surface with open and closed eyes. The standard deviation of the acceleration modulus and root mean square of the angular velocity modulus were calculated. The analysis was based on the intraclass correlation coefficient (ICC) to determine the internal consistency and feasibility. RESULTS: The ICC of the acceleration modulus was between 0.597 and 0.683 (P < 0.01), and the test-retest reliability was medium. The ICC of the angular velocity modulus was between 0.683 and 0.812 (P < 0.01, P < 0.001), and the test-retest reliability was medium to good. The standard error of measurement (SEM) of the acceleration modulus was between 0.001591 and 0.007248 (g), and the SEM% was between 21.24% and 34.12%. The angular velocity modulus SEM values ranged from 1.296 to 3.441 (deg/s), and the SEM% ranged from 25.17% to 33.26%. The difference between the two tests was evenly distributed on both sides of the mean value, and the difference between the test results was within the consistency limit. SIGNIFICANCE: Inertial sensors can be used to evaluate the static balance ability of preschoolers aged 4-5 years. Further, the angular velocity modulus is more reliable than the acceleration modulus.

Anion-exchange reactions: facile and general access to sensitive photoelectrochemical platforms for biomarker immunosensing.

Affordable methodologies for detecting tumor markers at low concentrations are very important for early diagnosis. The two key requirements for designing ultrasensitive photoelectrochemical (PEC) immunosensors are highly active PEC platforms and amplified recognition events on the transducer surfaces. Herein we report the development of an effective and general strategy for the sensitive immunoassay of biomarkers using a novel PEC platform. In particular, in contrast to traditional photoanode materials prepared by introducing well-stabilized quantum dots onto an electrode, in this work CdSe nanocrystal (NC)-based PEC films were first formed directly on an ITO surface by an anion-exchange reaction and followed by coverage with organic stabilizers. The compacted CdSe film produces ultrahigh photocurrent signals under visible-light irradiation (λ = 470 nm). Using rabbit immunoglobulin G (RIgG) as a model biomarker, we showed that through biotin-avidin bridges, biotin-functionalized peroxidase (B-HRP) could be further assembled and could catalyze the conversion of its substrate, 4-chloro-1-naphthol (4-CN), to realize precipitation of nonconductive benzo-4-chlorohexadienone on the CdSe surface, thus resulting in blocking of the electron donors and absorption of the incident light. As the resulting photocurrent decrease was directly related to the target concentration, a sensitive PEC immunoassay could be constructed. The target RIgG was detected over a concentration range from 1.0 fg mL-1 to 10 µg mL-1 with an ultralow detection limit of 0.5 fg mL-1. This study presents a promising and general strategy for the development of highly sensitive PEC biosensors, which can be extended to the detection of other enzymes and biomolecules.

Pt-Decorated g-C3N4/TiO2 Nanotube Arrays with Enhanced Visible-Light Photocatalytic Activity for H2 Evolution.

Aligned TiO2 nanotube layers (TiNTs) grown by self-organizing anodization of a Ti-substrate in a fluoride-based electrolyte were decorated with graphitic-phase C3N4 (g-C3N4) via a facile chemical vapor deposition approach. In comparison with classical TiO2 nanotubes (anatase), the g-C3N4/TiNTs show an onset of the photocurrent at 2.4 eV (vs. 3.2 eV for anatase) with a considerably high photocurrent magnitude in the visible range. After further decoration with Pt nanoparticles, we obtained a visible-light responsive platform that showed, compared with g-C3N4-free TiNTs, a strong enhancement for photoelectrochemical and bias-free H2 evolution (15.62 µLh-1 cm-2), which was almost a 98-fold increase in the H2 production rate of TiNTs (0.16 µLh-1 cm-2). In a wider context, the g-C3N4-combined 3 D nanoporous/nanotubular structure thus provides a platform with significant visible-light response in photocatalytic applications.

Development of amperometric glucose biosensor based on Prussian Blue functionlized TiO2 nanotube arrays.

Amperometric biosensors consisting of oxidase and peroxidase have attracted great attention because of their wide application. The current work demonstrates a novel approach to construct an enzymatic biosensor based on TiO2 nanotube arrays (TiNTs) as a supporting electrode on which Prussian Blue (PB)-an "artificial enzyme peroxidase" and enzyme glucose oxidase (GOx) have been immobilized. For this, PB nanocrystals are deposited onto the nanotube wall photocatalytically using the intrinsic photocatalytical property of TiO2, and the GOx/AuNPs nanobiocomposites are subsequently immobilized into the nanotubes via the electrodeposition of polymer. The resulting electrode exhibits a fast response, wide linear range, and good stability for glucose sensing. The sensitivity of the sensor is as high as 248 mA M(-1) cm(-2), and the detection limit is about 3.2 µM. These findings demonstrate a promising strategy to integrate enzymes and TiNTs, which could provide an analytical access to a large group of enzymes for bioelectrochemical applications including biosensors and biofuel cells.