Injectable Human Hair Keratin–Fibrinogen Hydrogels for Engineering 3D Microenvironments to Accelerate Oral Tissue Regeneration

Traumatic injury of the oral cavity is atypical and often accompanied by uncontrolled bleeding and inflammation. Injectable hydrogels have been considered to be promising candidates for the treatment of oral injuries because of their simple formulation, minimally invasive application technique, and site-specific delivery. Fibrinogen-based hydrogels have been widely explored as effective materials for wound healing in tissue engineering due to their uniqueness. Recently, an injectable foam has taken the spotlight. However, the fibrin component of this biomaterial is relatively stiff. To address these challenges, we created keratin-conjugated fibrinogen (KRT-FIB). This study aimed to develop a novel keratin biomaterial and assess cell–biomaterial interactions. Consequently, a novel injectable KRT-FIB hydrogel was optimized through rheological measurements, and its injection performance, swelling behavior, and surface morphology were investigated. We observed an excellent cell viability, proliferation, and migration/cell–cell interaction, indicating that the novel KRT-FIB-injectable hydrogel is a promising platform for oral tissue regeneration with a high clinical applicability.     

Object‐order template‐based approach for stereoscopic volume rendering

Stereoscopic volume rendering provides powerful depth information, but it takes a long time to render two‐eye images. Previous algorithms based on reprojection methods project the result of one view of a stereo pair into the other instead of rendering a new one completely. Because of inaccurate mapping between the two images, the quality of the reprojected image is not satisfactory. This paper presents a new algorithm to preserve the accuracy of both images with very little increase in computation time. The efficiency of the new algorithm comes from the use of ray templates and object‐order processing. This algorithm makes two different templates for each eye and renders two images simultaneously, tracing the volume only once in object order. We also extend the algorithm to support image‐space supersampling by using more ray templates. Experimental results show that the image quality of the new algorithm is not only comparable with that of ray casting but also the rendering speed is near that of the interactive shear–warp algorithm employing object‐order processing and spatial data coherency. Copyright © 1999 John Wiley & Sons, Ltd.     

A numerical study on fluid flow around two side-by-side rectangular cylinders with different arrangements

This study numerically examines the flow around a pair of parallel rectangular cylinders placed perpendicular to the direction of the flow using the immersed boundary method at a fixed Reynolds number of 100. A total of eight spacing ratios between 0.1 and 2 are considered in the two arrangements of the cylinders. The two cylinders are arrayed in inline and a staggered arrangement. The pattern of the wake of the two cylinders depends on their arrangements and spacing. The results, show four flow regimes: (i) A single bluff-body regime, (ii) an asymmetric wake regime, (iii) a transition regime, and (iv) a coupled street regime. All flow regimes appear in the case of the inline arrangement. In the case of the staggered arrangement, only the three flow regimes other than the coupled street flow regime are shown. The flow characteristics depend on the flow regime, including the flow structure, drag force, lift force, and frequency. We analyzed the flow characteristics by comparing the flow regimes, vortex shapes, drag and lift coefficients, and Strouhal numbers, which depended on the arrangement. The results of the drag, lift, and Strouhal numbers depend on the interaction of the jet that forms between the cylinders and the adjacent wakes near the cylinder. Therefore, the flow characteristics are sensitive to the arrangement and the distance between the cylinders.

     

Preparation of Nafion-sulfonated clay nanocomposite membrane for direct menthol fuel cells via a film coating process

Nafion sulfonated clay nanocomposite membranes were successfully produced via a film coating process using a pilot coating machine. For producing the composite membranes, we optimized the solvent ratio of N-methyl-2-pyrrolidinone (NMP) to N,N′-dimethylacetamide (DMAc), the amount of sulfonated montmorillonite (S-MMT) in composite membranes and the overall concentration of composite dispersions. Based on the optimized viscosity and composition, the composite dispersions were coated on a poly(ethylene terephthalate) (PET) substrate film. The distance between a metering roll and a PET film and the ratio of metering roll speed versus coating roll speed of the pilot coating machine were varied to control membrane thickness. The film coated composite membrane exhibited enhanced properties in the swelling behavior against MeOH solution, ion conductivity and MeOH permeability, compared to the cast Nafion composite membrane due to the higher dispersion state of S-MMT in Nafion matrix and the uniform distribution of small-size ion clusters. These properties influenced a cell performance test of a direct methanol fuel cell (DMFC), showing the film coated composite membrane had a higher power density than that of Nafion 115. The power density was also related with the higher selectivity of the composite membrane than Nafion 115.     

Unsteady characteristics of laminar free convection in an enclosure in the presence of power law fluid at Ra = 107

Journal of Mechanical Science and Technology - The present study deals with an unsteady laminar free convection inside the annuli confined between an outer square enclosure and an inner circular...     

Fuzzy set based crack diagnosis system for reinforced concrete structures

This paper presents a computer assisted crack diagnosis system for reinforced concrete structures which aids the non-expert to diagnose the cause of cracks at the level of an expert in the general inspection of structures. The system presented adapts fuzzy set theory to reflect fuzzy conditions, both for crack symptoms and characteristics which are difficult to treat using crisp sets. The inputs to the system are mostly linguistic variables concerning the crack symptoms and some numeric data about concrete and environmental conditions. Using these input data and based on built-in rules, the proposed system executes fuzzy inference to evaluate the crack causes under consideration. The built-in rules were constructed by extracting expert knowledge, primarily from technical books about concrete and concrete cracks. We implemented the proposed system in a computer program with a graphic user interface for actual utilization in practical business fields. When applied to cracks actually diagnosed by experts, the proposed system provided results similar to those obtained by experts, and we expect that this system can be used as an effective crack diagnosis tool for both experts and non-experts in the regular inspection of RC structures.     

Estimation of reaction conditions for synthesis of nanosized brookite-type titanium dioxide from aqueous TiOCl<Subscript>2</Subscript> solution

Ti O₂ nanoparticles with a mixture of brookite and rutile phases were prepared from aqueous TiOCl₂ solution at 80–150°C and pure rutile phase at 200°C. The volume fraction of brookite was gradually increased with increase of HCl concentration in the range of about 4.43 M to 6.28 M. The maximum volume fraction of brookite in the as-prepared TiO₂ particles was obtained when oxidation of Ti⁴⁺ to TiO₂ was completed but it was gradually decreased with increase of reaction time. The reaction time for complete oxidation of Ti^{4 +} to TiO₂ was about 15 h at 80°C, about 5 h at 100°C, about 2 h at 120°C, and about 1 h at 150°C, respectively, showing that the kinetics of oxidation is very dependent on the reaction temperature. Brookite phase was not transformed directly to rutile phase but to anatase phase by heat-treatment at about 750°C, which finally converted to rutile phase at 1100°C.     

Electrophoretic and dynamic light scattering in evaluating dispersion and size distribution of single-walled carbon nanotubes

We have introduced both electrophoretic and dynamic light scattering to evaluate the polydispersity, nanodispersity, and stability of single-walled carbon nanotubes (SWNTs) in distilled water with surfactants. By controlling the sodium dodecyl sulfate composition and some pretreatment by sonication, we were able to achieve nanodispersion (dispersion into individual nanotubes). The polydispersity was well described by combining both methods. We further showed that the nanodispersion and length distribution observed in the dynamic light scattering spectra were clearly identified by atomic force microscopy. Although surfactants with aliphatic groups can nanodisperse SWNT bundles, the dispersivity and stability depended seriously on the sample preparation process. Our measurements showed that a combination of electrophoretic and dynamic light scattering can provide a convenient and robust means of measuring polydispersity, nanodispersity, and stability of SWNTs in various solutions.     

Surface current and charge density induced on aircraft

The usefulness of the geometrical theory of diffraction (GTD) in computing the surface current and charge density induced on aircraft is illustrated. This is a high-frequency solution for an arbitrary incident plane wave and fuselage observation points. A pattern is presented for an arbitrary incident plane wave as well as a series of frequency and time domain plots for roll plane incidence. A 3-dimensional pattern is presented for plane wave incidence (as a function of incidence angle) as well as examples of roll plane results in both the frequency and time domain.     

Investigation of the characteristics of a stacked direct borohydride fuel cell for portable applications

To investigate the possibility of the portable application of a direct borohydride fuel cell (DBFC), weight reduction of the stack and high stacking of the cells are investigated for practical running conditions. For weight reduction, carbon graphite is adopted as the bipolar plate material even though it has disadvantages in tight stacking, which results in stacking loss from insufficient material strength. For high stacking, it is essential to have a uniform fuel distribution among cells and channels to maintain equal electric load on each cell. In particular, the design of the anode channel is important because active hydrogen generation causes non-uniformity in the fuel flow-field of the cells and channels. To reduce the disadvantages of stacking force margin and fuel maldistribution, an O-ring type-sealing system with an internal manifold and a parallel anode channel design is adopted, and the characteristics of a single and a five-cell fuel cell stack are analyzed. By adopting carbon graphite, the stack weight can be reduced by 4.2 times with 12% of performance degradation from the insufficient stacking force. When cells are stacked, the performance exceeds the single-cell performance because of the stack temperature increase from the reduction of the radiation area from the narrow stacking of cells.