The ovonic threshold switch (OTS) based on the voltage snapback of amorphous chalcogenides possesses several desirable characteristics: bidirectional switching, a controllable threshold voltage (V ) and processability for three-dimensional stackable devices. Among the materials that can be used as OTS, GeSe has a strong glass-forming ability (∼350 °C crystallization temperature), with a simple binary composition. Described herein is a new method of depositing GeSe films through atomic layer deposition (ALD), using HGeCl and [(CH)Si]Se as Ge and Se precursors, respectively. The stoichiometric GeSe thin films were formed through a ligand exchange reaction between the two precursor molecules, without the adoption of an additional reaction gas, at low substrate temperatures ranging from 70 °C-150 °C. The pseudo-saturation behavior required a long time of Ge precursor injection to achieve the saturation growth rate. This was due to the adverse influence of the physisorbed precursor and byproduct molecules on the efficient chemical adsorption reaction between the precursors and reaction sites. To overcome the slow saturation and excessive use of the Ge precursor, the discrete feeding method (DFM), where HGeCl is supplied multiple times consecutively with subdivided pulse times, was adopted. DFM led to the saturation of the GeSe growth rate at a much shorter total injection time of the Ge precursor, and improved the film density and oxidation resistance properties. The GeSe film grown via DFM exhibited a short OTS time of ∼40 ns, a ∼10 ON/OFF current ratio, and ∼10 selectivity. The OTS behavior was consistent with the modified Poole-Frenkel mechanism in the OFF state. In contrast, the similar GeSe film grown through the conventional ALD showed a low density and high vulnerability to oxidation, which prevented the OTS performance. The ALD method of GeSe films introduced here will contribute to the fabrication of a three-dimensionally integrated memory as a selector device for preventing sneak current.
BACKGROUND: Trunk stability has been identified as an important prerequisite of functional movement. OBJECTIVE: To investigate the effectiveness of core muscle contraction training on abdominal muscle thickness, balance, and gait ability in stroke patients. METHODS: Thirty patients with stroke were randomly assigned to two experimental groups and a control group. All groups received conventional therapeutic exercise program for six weeks. The experimental groups additionally trained trunk stability exercise with abdominal hollowing or bracing maneuvers within training time. Primary outcome measures were evaluated abdominal muscle thickness using the sonography. Secondary outcome measures were evaluated by the Functional Reach Test (FRT), Berg Balance Scale (BBS), 10-meter walk test (10MWT), and Timed Up and Go test (TUG). RESULTS: Compared with the control group, the effect of trunk stability training for the experimental groups on the abdominal muscles thickness change was observed (p < 0.05). The values in balance and gait measures, BBS, FRT, 10MWT, and TUG, showed significant improvement after the intervention periods (p < 0.05), although no significant differences were found in scores of gait and balance scales among groups. CONCLUSIONS: Trunk stability training with selective abdominal muscles activation has beneficial effects on abdominal muscles, balance, and mobility in stroke patients. Our findings might provide support for introducing stroke rehabilitation.
-In this paper, a novel planar type magnetic levitation system without other assistant devices is proposed and it can move with 6 degree of freedom (X, Y, Z, θ X , θ Y , θ Z ) in wafer size as well as in nano scale positioning.The mover is composed with 2-D Halbach permanent magnet array and the stator is composed with 10 x 10 coil arrays.It was composed in laboratory and tested with short stroke (4 [
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