An Active and Soft Hydrogel Actuator to Stimulate Live Cell Clusters by Self-folding

The hydrogels are widely used in various applications, and their successful uses depend on controlling the mechanical properties. In this study, we present an advanced strategy to develop hydrogel actuator designed to stimulate live cell clusters by self-folding. The hydrogel actuator consisting of two layers with different expansion ratios were fabricated to have various curvatures in self-folding. The expansion ratio of the hydrogel tuned with the molecular weight and concentration of gel-forming polymers, and temperature-sensitive molecules in a controlled manner. As a result, the hydrogel actuator could stimulate live cell clusters by compression and tension repeatedly, in response to temperature. The cell clusters were compressed in the 0.7-fold decreases of the radius of curvature with 1.0 mm in room temperature, as compared to that of 1.4 mm in 37 degrees C. Interestingly, the vascular endothelial growth factor (VEGF) and insulin-like growth factor-binding protein-2 (IGFBP-2) in MCF-7 tumor cells exposed by mechanical stimulation was expressed more than in those without stimulation. Overall, this new strategy to prepare the active and soft hydrogel actuator would be actively used in tissue engineering, drug delivery, and micro-scale actuators

Effects of pre-existing hydrogen to stress triaxiality and damage evolution on ultra high strength steel

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A New Hardware Correlator in Korea: Performance Evaluation using KVN observations

We report results of the performance evaluation of a new hardware correlator in Korea, the Daejeon correlator, developed by the Korea Astronomy and Space Science Institute (KASI) and the National Astronomical Observatory of Japan (NAOJ). We conducted Very Long Baseline Interferometry (VLBI) observations at 22~GHz with the Korean VLBI Network (KVN) in Korea and the VLBI Exploration of Radio Astrometry (VERA) in Japan, and correlated the aquired data with the Daejeon correlator. For evaluating the performance of the new hardware correlator, we compared the correlation outputs from the Daejeon correlator for KVN observations with those from a software correlator, the Distributed FX (DiFX). We investigated the correlated flux densities and brightness distributions of extragalactic compact radio sources. The comparison of the two correlator outputs show that they are consistent with each other within $<8\%$, which is comparable with the amplitude calibration uncertainties of KVN observations at 22~GHz. We also found that the 8\% difference in flux density is caused mainly by (a) the difference in the way of fringe phase tracking between the DiFX software correlator and the Daejeon hardware correlator, and (b) an unusual pattern (a double-layer pattern) of the amplitude correlation output from the Daejeon correlator. The visibility amplitude loss by the double-layer pattern is as small as 3\%. We conclude that the new hardware correlator produces reasonable correlation outputs for continuum observations, which are consistent with the outputs from the DiFX software correlator.Comment: 13 pagee, 9 figures, 3 tables, to appear in JKAS (received February 9, 2015; accepted March 16, 2015

Patterned Si thin film electrodes for enhancing structural stability

A patterned film (electrode) with lozenge-shaped Si tiles could be successfully fabricated by masking with an expanded metal foil during film deposition. Its electrochemical properties and structural stability during the charge-discharge process were examined and compared with those of a continuous (conventional) film electrode. The patterned electrode exhibited a remarkably improved cycleability (75% capacity retention after 120 cycles) and an enhanced structural stability compared to the continuous electrode. The good electrochemical performance of the patterned electrode was attributed to the space between Si tiles that acted as a buffer against the volume change of the Si electrode

Comparison of Characteristics According to Reflux Type in Patients With Laryngopharyngeal Reflux

Objectives To analyze laryngopharyngeal reflux (LPR) as an acidic, nonacidic, or mixed type according to 24-hour multi-channel intraluminal impedance (MII) pH monitoring and the clinical characteristics of each type. Methods Ninety patients were prospectively enrolled in this study. All patients underwent 24-hour MII pH monitoring as a diagnostic tool. Eighty-three patients were diagnosed with LPR. The patients were classified into three groups according to the pH of the hypopharyngeal probe: the acid reflux group, nonacid reflux group, and mixed reflux group. Subjective symptoms and objective findings were evaluated based on patients’ responses to the Short Form 12 Survey (SF-12), LPR health-related quality of life (LPR-HRQOL), reflux symptom index, and reflux finding score. Results The results of each group were compared. As a result, 34 patients were classified into the nonacid reflux group and 49 into the mixed reflux group. There were no patients classified as having acid reflux alone. There was no significant difference between the two groups when comparing the reflux symptom index, reflux finding score, LPR-HRQOL, or the mental component score of the SF-12. However, the physical component score of the SF-12 was higher in the nonacid reflux group (P=0.018). The DeMeester composite score (P=0.015) and total number of LPR events (P=0.001) were lower in the nonacid reflux group than in the mixed reflux group. Conclusion In conclusion, no LPR patient had only acid reflux. The nonacid reflux LPR patients showed similar clinical characteristics and findings compared to the mixed reflux group, but exhibited significantly fewer LPR episodes