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Introduction. This study aimed to evaluate the effects of resorbable blasting media (RBM) treatment on early stability of orthodontic mini-implants by mechanical, histomorphometric, and histological analyses. Methods. Ninety-six (64 for mechanical study and 32 for histological study and histomorphometric analysis) titanium orthodontic mini-implants (OMIs) with machined (machined group) or RBM-treated (CaP) surface (RBM group) were implanted in the tibiae of 24 rabbits. Maximum initial torque (MIT) was measured during insertion, and maximum removal torque (MRT) and removal angular momentum (RAM) were measured at 2 and 4 weeks after implantation. Bone-to-implant contact (BIC) and bone area (BA) were analyzed at 4 weeks after implantation. Results. RBM group exhibited significantly lower MIT and significantly higher MRT and RAM at 2 weeks than machined group. No significant difference in MRT, RAM, and BIC between the two groups was noted at 4 weeks, although BA was significantly higher in RBM group than in machined group. RBM group showed little bone resorption, whereas machined group showed new bone formation after bone resorption. Conclusions. RBM surface treatment can provide early stability of OMIs around 2 weeks after insertion, whereas stability of machined surface OMIs may decrease in early stages because of bone resorption, although it can subsequently recover by new bone apposition. [ABSTRACT FROM AUTHOR]

High voltage electric power equipment requires rigorous regulation testing to specific standards which ensure proper and safe operation in the grid. Manufacturers conduct these tests in order to prove standard compliance and product liability. Variable linear or nonlinear loads are necessary for testing medium voltage (MV) high power AC power converters. Generally, those AC power converters or power supplies require performance validation, burn-in and/or lifetime testing under different load conditions, defined by the end-user or standards for the given applications. For flexible and efficient MV verification testing, this paper presents a five-level multilevel converter-based MV regenerative AC electronic load with one-cycle control (OCC), which is based on five-level diode-clamped multilevel converters with back-to-back structure and can emulate any impedance load. In this paper, especially the dc-link capacitor voltage balance of the proposed multilevel MV regenerative AC load is deeply analyzed. Simulation and experimental results are presented to verify the dc-link voltage balance performance of the proposed multilevel MV regenerative AC electronic load. [ABSTRACT FROM AUTHOR]

This paper presents a new multilevel one-cycle control (OCC) technique for a five-level diode-clamped multilevel converter (DCMC)-based static VAR compensator (STATCOM). The OCC algorithm in combination with multi-carrier level-shifted PWM control is used in the proposed five-level DCMC-based STATCOM. The automatic dc link voltage balance is simply realized by four voltage compensators presented as the part of the OCC controller. In this paper the OCC principle of a two-level converter-based STATCOM is reviewed and extended to the five-level DCMC-based STATCOM. The proposed multilevel OCC control method of the five-level DCMC-based STATCOM in steady-state and dynamic operation modes is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

• A Ti-based reinforced Ti 2 Ni/Ti 2 S coating was fabricated by laser cladding on TC4 alloy. • The thermodynamic characteristics of the laser molten pool were described. • The orientation relationships of β-Ti and TiC were determined. • The microhardness and wear resistance of the deposited coating were improved. In this study, a Ti 2 Ni/Ti 2 S reinforced Ti-based composite coating was fabricated using laser cladding to improve the mechanical properties of TC4 alloy. The results show that the high temperature (>3000 K) of the molten pool ensures the effectiveness of the deposited coating and the thermodynamic conditions for in situ reactions. The phases consisted of β-Ti, Ti 2 Ni, Ti 2 S, TiC, and WC. Furthermore, β-Ti nucleated and grew with TiC as heterogeneous cores due to their orientation relationships of β-Ti{1 0 0}//TiC{1 1 0} and β-Ti{1 1 0}//TiC{1 1 1}. As a result, the microhardness of the coating was 2.30 times higher than the substrate, and the wear volume decreased by 20.23 % compared to the substrate. [ABSTRACT FROM AUTHOR]

In this study, an enhanced surface composite coating with improved nano-hardness was successfully prepared on Ti811 alloy by means of laser cladding processing. The microstructure, phase composition, interface structure, and nano-hardness of the composite coating were systematically investigated. The results show that the Ti-based cladding coating contains CrTi 4 , Ti 2 Ni, TiC, α-Ti, and CeCrO 3. The single-track and multi-track overlapping regions of the coating form a fine metallurgical combination with the substrate and exhibit different microstructure characteristics due to differential cooling rates. The CrTi 4 -α-Ti transformation follows the Burgers orientation relationship, and the pinning effect of CeCrO 3 particles distributed at the grain boundaries effectively refines the CrTi 4 matrix. Moreover, the effective combination between interfaces ensures the improved nano-hardness of the coating. The results of this study provide a general guideline for studying the microstructure evolution and nano-hardness of composite coatings fabricated on titanium alloys using laser cladding technology or other additive manufacturing methods. [ABSTRACT FROM AUTHOR]

Wearable device‐based gait data analysis is being used in medical research to prevent and treat serious diseases such as dementia beyond modern health management strategies. For gait‐related data collection and analysis, it is advantageous to place the sensor on the sole of the foot as a foot‐pressure, it is advantageous to use a piezoelectric generator‐based electronic textile (E‐textile) that can supply its own power by converting mechanical energy from the foot into electrical energy. In order to apply E‐textile materials to the sole of the foot, excellent durability, flexibility, and high signal accuracy through noise minimization are required. In this study, a piezoelectric polymer was used to coat the surface of a conductive fiber using the reverse dip coating technique. This method is easily scalable, feasible for large‐scale processing with a continuous process. The electrodes of this process are placed inside a piezoelectric fiber to minimize noise from the electrodes. The inner‐electrode piezoelectric yarn (IEPY) used during the process has excellent tensile strength (maximum stress and strain value: 54.2 MPa, 54%) and strong durability, maintaining its performance over 105 cycles under pushing force of 60 kg and generating excellent piezoelectric output (292 mVmax, 16.2 µW). The IEPY can drive the sensor for gait data, with the sensors being capable of continuous and large‐scale operation and feasible for the manufacturing of custom sensors. [ABSTRACT FROM AUTHOR]

• The atomic structure of silicon irradiated by femtosecond laser was characterized. • The laser irradiated silicon region consists of a dislocation layer. • The existence of the dislocation layer enhances the nano-hardness of silicon. In this work, a one-step fs laser-induced monocrystalline silicon (Si) structure was fabricated to improve the nano-hardness properties. According to the atomic structure, three layers were found in the irradiated Si structure, namely, the amorphous Si (a-Si) layer, dislocation layer, and Si crystal layer. The a-Si layer on the surface layer was attributed to the re-solidification of melting Si material, while the dislocation layer between the a-Si and Si crystal layers contained numerous dislocations and lattice distortions, which positively affected the nano-hardness of the irradiated Si structure. The Si crystal layer was not affected by laser irradiation and maintained the initial atomic structure. This work provides a new perspective on the phase transition and microstructure study of fs laser-induced structures. [ABSTRACT FROM AUTHOR]

This study covers a self-powered wireless communication system that is powered using a piezoelectric energy harvester (PEH) in a shoe. The lead-zirconate-titanate (PZT) ceramic of the PEH was coated with UV resin, which (after curing under UV light) allowed it to withstand periodic pressure. The PEH was designed with a simple structure and placed under the sole of a shoe. The durability of the PEH was tested using a pushing tester and its applicability in shoes was examined. With periodic compression of 60 kg, the PEH produced 52 μW of energy at 280 kΩ. The energy generated by the PEH was used to power a wireless transmitter. A step-down converter with an under-voltage lockout function was used to gather enough energy to operate the wireless transmitter. The transmitter can be operated initially after walking 24 steps. After the transmitter has been activated, it can be operated again after 8 steps. Because a control center receives signals from the transmitter, it is possible to check the status of workers who work outside at night or mostly alone, to detect emergencies. [ABSTRACT FROM AUTHOR]