Structural and electrochemical properties of vanadium oxide thin films grown by d.c. and r.f. reactive sputtering at room temperature

Vanadium oxide thin films were grown at room temperature by direct current and radio-frequency reactive sputtering systems to compare the structural and electrochemical properties. Rutherford backscattering spectrometry and Fourier transform infrared measurements reveal that the composition of the as-deposited films consists of the V₂O₅ phase regardless of the deposition methods. Wide-angle X-ray diffraction measurements show that the crystallinity of the as-deposited V₂O₅ films is different depending on the deposition method. Films deposited by direct current reactive sputtering were amorphous, whereas films deposited by radio-frequency reactive sputtering were crystalline. Scanning electron microscopy measurements show that the V₂O₅ films grown by radio-frequency reactive sputtering had a large grain size but the films grown by direct current reactive sputtering were amorphous. Charge–discharge measurements taken at room temperature with a constant current clearly indicate that the films grown by direct current sputtering demonstrated typical amorphous behavior, whereas the V₂O₅ films grown by radio-frequency sputtering demonstrated the discharge behavior of crystalline V₂O₅. The origin of the structural and electrochemical properties of film grown by radio-frequency reactive sputtering is a self-bias effect. The self-bias effect induces ion bombardment during the growth of vanadium oxide thin film. These results suggest that direct current reactive sputtering is more desirable for growing amorphous V₂O₅ thin film than radio-frequency reactive sputtering.     

Biomimetic micropatterning of silica by surface-initiated polymerization and microcontact printing

Micropatterns of silica on a gold substrate were generated by a biomimetic approach, namely, the biosilicification of silicic acids. The procedure consists of three simple steps: pattern generation of a polymerization initiator, (BrC(CH(3))(2)COO(CH(2))(11)S)(2), by microcontact printing; surface-initiated, atom-transfer radical polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) from the patterned area; and polycondensation of silicic acids. The tertiary amine-containing polymer, pDMAEMA, aided in the spatially controlled polycondensation of silicic acids on surfaces in the presence of phosphate ions, and micropatterns of silica on a gold substrate were successfully generated in combination with the technique of microcontact printing. The procedure could be extended to the controlled fabrication of silica patterns with any size, shape, or thickness.     

Effect of surface structure on biomechanical properties and osseointegration

The purpose of this study is to improve the bone-bonding ability between titanium implants and living bone through the control of geometric design and chemical compositions of an implant surface. We compared the tissue healing response and resulting implant stability for three surface designs by characterizing the histological and mechanical properties of the healing tissue around smooth-surfaced Ti–6Al–4V (SS), CP-Ti plasma-spray-coated (PSC), alkali- and heat-treated (AHT) implants. The implants were transversely inserted into a dog thighbone and evaluated at 4, 8, and 12 weeks. Histological examination indicated that initial matrix mineralization leading to osseointegration occurred more rapidly with the AHT implant. During the 4, 8, and 12 week healing periods, new bone on the surface of AHT implant showed denser growth than that on the SS and PSC implants. The more extensive tissue integration and more rapid matrix mineralization with the AHT implant were reflected in the mechanical test data, which demonstrated superior attachment strength and interfacial stiffness for the AHT implant after healing for 4, 8 and 12 weeks of healing because of the mechanical interlocking in the micrometer sized rough surface and the large bonding area between bone and implant caused by the nanosized porous surface structure. Histological and mechanical data demonstrate that with the appropriate surface design selection, bone bone-bonding ability can be improved and can induce acceleration of the healing response, thereby improving the potential for implant osseointegration.     

A study on the factors that affect the adoption of Smart Water Grid

Due to recent climate changes that accompany drastic changes in water recycle process, extreme floods and droughts are occurring frequently throughout the world. In response to these events, Smart Water Management that refers to implement intelligent water information systems by IT convergence is considered as a new paradigm. In this study, we seek to explore the Smart Water Management, especially the adoption of Smart Water Grid Technology. We aim to review previous studies to identify factors that influence the adoption of the Smart Water Grid and to analyze the importance and priority of the factors affecting Smart Water Grid adoption, thereby presenting the successful adoption measures for Smart Water Grid in Korea. This study set a research model with the influencing factors in relation to the adoption of new IT technologies that were identified through the literature reviews of previous studies based on the TOE framework. This study also conducted empirical analysis of the findings and found out that the issue of privacy protection and security due to hacker’s attack would be emerged as a significant risk factor.     

Characterization of the Secretome of a Specific Cell Expressing Mutant Methionyl-tRNA Synthetase in Co-Culture Using Click Chemistry

Co-culture system, in which two or more distinct cell types are cultured together, is advantageous in that it can mimic the environment of the in vivo niche of the cells. In this study, we presented a strategy to analyze the secretome of a specific cell type under the co-culture condition in serum-supplemented media. For the cell-specific secretome analysis, we expressed the mouse mutant methionyl-tRNA synthetase for the incorporation of the non-canonical amino acid, azidonorleucine into the newly synthesized proteins in cells of which the secretome is targeted. The azidonorleucine-tagged secretome could be enriched, based on click chemistry, and distinguished from any other contaminating proteins, either from the cell culture media or the other cells co-cultured with the cells of interest. In order to have more reliable true-positive identifications of cell-specific secretory bodies, we established criteria to exclude any identified human peptide matched to bovine proteins. As a result, we identified a maximum of 719 secreted proteins in the secretome analysis under this co-culture condition. Last, we applied this platform to profile the secretome of mesenchymal stem cells and predicted its therapeutic potential on osteoarthritis based on secretome analysis.     

The Regenerative Effects of c-Met Agonistic Antibodies in Vocal Fold Atrophy

Background: Atrophy of the vocal folds and the accompanying glottic insufficiency affect the quality of life. Although growth factors have been used to treat muscle atrophy, their effectiveness is limited by their short half-life. Methods: In total, 15 rabbits and 24 rats were used for the study. The right recurrent laryngeal nerves of all animals were transected. One month following nerve transection, PBS (PBS group), rHGF (HGF group), or a c-Met agonistic antibody (c-Met group) was injected into the paralyzed vocal folds. The larynges of the rabbits were harvested from each group for histologic examination and subjected to PCR analysis. Results: Cross-sectional areas (CSAs) of thyroarytenoid muscles were evaluated. The c-Met group had increased CSAs compared to the PBS and HGF groups, but there were no significant differences compared to normal controls. The expression levels of myogenesis-related genes were evaluated three weeks after the injection. The expression levels of myosin heavy chain IIa were significantly increased in the PBS group, while the expression levels of MyoD were increased in the c-Met group. Conclusions: The c-Met agonistic antibody showed promise for promoting muscle regeneration in a vocal fold palsy model.     

Structural dynamic displacement vision system using digital image processing

This study introduces dynamic displacement vision system (DDVS), which is applicable for imaging unapproachable structures using a hand-held digital video camcorder and is more economical than the existing contact and contactless measurement methods of dynamic displacement and deformation. This proposed DDVS method is applied to the Region of Interest (ROI) resizing and coefficient updating at each time step to improve the accuracy of the measurement from the digital image. Thus, after evaluating the algorithms conducted in this study by the static and dynamic verification, the measurement's usability by calculating the dynamic displacement of the masonry specimen, and the two-story steel frame specimen is evaluated under uniaxial seismic loading. The algorithm of the proposed method in this study, despite the relatively low resolution during frozen, slow, and seismic motions, has precision and usability that can replace the existing displacement transducer. Moreover, the method can be effectively applied to even fast behavior for multi-measurement positions like the seismic simulation test using large scale specimen. DDVS, using the consecutive images of the structures with an economic, hand-held digital video camcorder is a more economical displacement sensing concept than the existing contact and contactless measurement methods.     

Optimal haulage routing of off-road dump trucks in construction and mining sites using Google Earth and a modified least-cost path algorithm

This study presents new software, called Google Earth-based Optimal HAulage RouTing System (GEOHARTS), to improve the functionality of Google Earth for optimal haulage routing of off-road dump trucks in construction and mining sites. A modified least-cost path algorithm, which is applicable to working areas with both paved and unpaved temporary roads and can consider the effects of terrain relief and curves along a route on the route planning, was proposed and utilized for the software development. GEOHARTS can determine optimal haulage routes between loaders and dumps that ensure the least travel time or fuel consumption of off-road dump trucks and can visualize the results using an embedded 3D render window of Google Earth. The application to the Pasir open-pit coal mine in Indonesia demonstrates that GEOHARTS could provide a rational solution to support the truck haulage operations.     

Studies on the heating capacity control of a multi-type heat pump system applying a multi-input multi-output (MIMO) method

This paper describes a method to control capacity of a multi-type heat pump system. Because indoor units are interconnected, alteration of the heating or cooling setting of one indoor unit can influence the performance of the other indoor units. Proportional-integral (PI) controllers were used to assess system performance, and the PI controllers’ gain values were optimized by using a genetic algorithm. A system model was established following a system identification optimization process, and a pseudo random binary sequence was selected as the system identification input signal. A multi-input multi-output (MIMO) controller was more effective in reducing such cross-coupling effects than a single-input single-output (SISO) controller. The temperature at the secondary fluid outlet in the condenser and the saturation pressure at the evaporator were selected as the control variables in the MIMO controller. The experimental results showed that an optimized MIMO controller could reduce overshoot by up to 40% compared with the results using a SISO controller.