Monitoring biofilm development in a microfluidic device using modified confocal reflection microscopy

The feasibility of a method to monitor biofilm development non-destructively in a microfluidic device was addressed. Here, we report that biofilm growth could be non-destructively monitored by an image analysis technique based on modification of confocal reflection microscopy.     

Mechanical properties of silane‐treated,silica‐particle‐filled polyisoprene rubber composites: Effects of the loading amount and alkoxy group numbers of a silane coupling agent containing mercapto groups

The surface treatment of spherical silica particles with a silane coupling agent with mercapto groups was carried out. The treated silica particles were incorporated within polyisoprene and then vulcanized. The effects of the loading amount and alkoxy group number of silane on the stress–strain curve of the filled composite were investigated. For this purpose, silanes with dialkoxy and trialkoxy structures were used. The loading amount of silane on the silica surface was varied from 1 to 8 times the amount required for monolayer coverage. The stress at the same strain increased with the silane treatment, and it was higher in the dialkoxy structure than in the trialkoxy structure above 300% strain. There was no significant influence of the loading amount on the stress for the trialkoxy silane structure. However, the stress was influenced by the loading amount, and the maximum stress was observed at 4 times the silane amount required for monolayer coverage for the dialkoxy structure. The stress had a good relationship with the crosslinking density of silica‐filled polyisoprene rubber (measured with a swelling test). The reinforcement effect by the silane treatment of silica was found to be affected strongly both by the entanglement of the silane chain and polyisoprene rubber matrix and by the crosslinking reaction between the mercapto group of silane and polyisoprene rubber in the interfacial region. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Non-Volatile Intact Indole Glucosinolates are Host Recognition Cues for Ovipositing <Emphasis Type="Italic">Plutella xylostella</Emphasis>

The diamondback moth (Plutella xylostella), a crucifer-specialist pest, has been documented to employ glucosinolates as host recognition cues for oviposition. Through the use of mutant Arabidopsis thaliana plants, we investigated the role of specific classes of glucosinolates in the signaling of oviposition by P. xylostella in vivo. Indole glucosinolate production in A. thaliana was found to be crucial in attracting oviposition. Additionally, indole glucosinolates functioned as oviposition cues only when in their intact form. 4-Methoxy-indol-3-ylmethylglucosinolate was implicated as an especially strong oviposition attractant in vitro, suggesting that indole glucosinolate secondary structure may play a role in P. xylostella host recognition as well. Aliphatic glucosinolate-derived breakdown products were found to attract P. xylostella, but only after damage or in the absence of indole glucosinolates. Furthermore, mutant plants lacking both intact indole glucosinolates and aliphatic glucosinolate breakdown products exhibited decreased oviposition attractiveness beyond that of the progenitor mutants lacking either component of the glucosinolate-myrosinase system. Therefore, we conclude that nonvolatile indole glucosinolates and volatile aliphatic glucosinolate breakdown products both appear to play important roles as host recognition cues for P. xylostella oviposition.     

Thermal characteristics of a double-glazed external wall system with roll screen in cooling season

A double-skin system (double-glazed external wall) is an effective passive system that can be used to decrease solar heat gain into buildings. Detailed information on the thermal distribution of double-skin facades is necessary to design better systems that can provide thermal comfort and conserve energy. In this study, the three-dimensional thermal characteristics of double-skin facades that had the ventilation opening installed partially and were screened partially by the adjacent buildings were investigated by field measurements. To that end, field measurements were carried out on the double-skin exterior wall (9.4 m high and 27.0 m wide) installed in an atrium located in the west of an existing building during cooling period for typical summer conditions. Maximum air change rate of natural ventilation through the bottom opening up to the top opening is about 20–25 [1/h], the reduction ratio of total solar heat gain compared with those of non-natural ventilation is about 25%. The exhaust solar heat gain is about 100 W/m² per inner glass surface area of the double-skin facades. Air temperature distribution of air space in the double skin was ranged from 30 °C to 44 °C, and heat gain difference ranged from 50 W/m² to 130 W/m². The influence of the ventilation openings and the shade conditions on temperature distribution of double skin is found to be significant and the double-skin system was verified to reduce the cooling loads effectively.     

Evaporative concentration of a microdroplet for highly sensitive detection of trace heavy metal ions in real samples

The influence of surface tension becomes more prominent as the device is miniaturized. We used this effect to enhance the detection sensitivity of trace heavy metal ions. A microelectrode array was formed along with a Ag/AgCl reference electrode and was surrounded by a super-hydrophobic layer formed with polytetrafluoroethylene (PTFE) beads. When a droplet of a sample solution was placed on the sensing area, the super-hydrophobic layer repelled the solution and a spherical droplet was formed. The droplet shrank to the sensing area as the solution evaporated. Electrochemical preconcentration was then carried out with the concentrated solution. Three heavy metal ions (Cd²⁺, Pb²⁺, and As³⁺) were analyzed by square-wave anodic stripping voltammetry. A significant increase in current peaks was observed by this novel method. When a 10-µL droplet was used, the detection limit was 600 ppt for Pb²⁺ and As³⁺ ions and 900 ppt for Cd²⁺ ions. Furthermore, the effect of the evaporative concentration was enhanced by increasing the volume of sample solution. We used this device for analysis of real samples. Correlation between the values obtained by this method and a conventional method was satisfactory with correlation coefficients of 0.982 (Pb²⁺), 0.969 (Cd²⁺), and 0.936 (As³⁺). Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Any link between integrin degradation and water-holding capacity in pork?

In order to investigate a possible relationship between integrin degradation and water-holding capacity (WHC), integrin was quantified using western blot, and water mobility and distribution was measured by proton NMR T(2) relaxometry at 24h postmortem in pork (n=30) with a large variation in WHC (drip loss varying from 2.8% to 11.3%). Regression analyses revealed correlation coefficients of r=-0.32 (P=0.08) and r=0.40 (P=0.03) for the correlations between the content of integrin determined by western blot analysis and WHC determined as either drip loss or by NMR, respectively. Water mobility and distribution was also measured in 18 meat samples upon 7 days of aging, which revealed a correlation (r=0.54) between integrin content determined by western blot analysis 24h postmortem and the mobility of the myofibrillar water (T(21) relaxation time) at day 7. In contrast, no correlation could be established between integrin content 24h postmortem and WHC at day 7 determined by NMR as the amount of extramyofibrillar water (T(22) population) (r=-0.01). In conclusion, both visualisation by CLSM and quantification of integrin by western blot analyses of suggested that a strong link between integrin degradation and WHC in pork is questionable, whereas integrin degradation seems to have impact on the succeeding development in the mobility of the myofibrillar water.     

Size dependence of THz region dielectric properties for barium titanate fine particles

Barium titanate (BaTiO₃) crystallites with various particle sizes from 22 to 500 nm were prepared by the two-step thermal decomposition method of barium titanyl oxalate. Various characterizations revealed that these particles were impurity-free, defect-free, dense BaTiO₃ particles. The powder dielectric measurement clarified that the dielectric constant of BaTiO₃ particles with a size of around 58 nm exhibited a maximum of over 15,000. To explain this size dependence, the THz region dielectric properties of BaTiO₃ fine particles, especially Slater mode frequency, were measured using the far infrared (FIR) reflection method. As the result, the lowest Slater mode frequency was obtained at 58 nm. This tendency was completely consistent with particle size dependence of the dielectric constant.     

CD147-Cyclophilin a Interactions Promote Proliferation and Survival of Cutaneous T-Cell Lymphoma

CD147, a transmembrane glycoprotein that belongs to the immunoglobulin superfamily, and cyclophilin A (CypA), one of the binding partners of CD147, are overexpressed in tumor cells and associated with the progression of several malignancies, including both solid and hematological malignancies. However, CD147 and CypA involvement in cutaneous T-cell lymphoma (CTCL) has not been reported. In this study, we examined CD147 and CypA expression and function using clinical samples of mycosis fungoides (MF) and Sézary syndrome (SS) and CTCL cell lines. CD147 and CypA were overexpressed by tumor cells of MF/SS, and CypA was also expressed by epidermal keratinocytes in MF/SS lesional skin. Serum CypA levels were increased and correlated with disease severity markers in MF/SS patients. Anti-CD147 antibody and/or anti-CypA antibody suppressed the proliferation of CTCL cell lines, both in vitro and in vivo, via downregulation of phosphorylated extracellular-regulated kinase 1/2 and Akt. These results suggest that CD147-CypA interactions can contribute to the proliferation of MF/SS tumor cells in both a autocrine and paracrine manner, and that the disruption of CD147-CypA interactions could be a new therapeutic strategy for the treatment of MF/SS.     

Biomimetic Zirconia with Cactus-Inspired Meso-Scale Spikes and Nano-Trabeculae for Enhanced Bone Integration

Biomimetic design provides novel opportunities for enhancing and functionalizing biomaterials. Here we created a zirconia surface with cactus-inspired meso-scale spikes and bone-inspired nano-scale trabecular architecture and examined its biological activity in bone generation and integration. Crisscrossing laser etching successfully engraved 60 μm wide, cactus-inspired spikes on yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) with 200–300 nm trabecular bone-inspired interwoven structures on the entire surface. The height of the spikes was varied from 20 to 80 μm for optimization. Average roughness (Sa) increased from 0.10 μm (polished smooth surface) to 18.14 μm (80 μm-high spikes), while the surface area increased by up to 4.43 times. The measured dimensions of the spikes almost perfectly correlated with their estimated dimensions (R² = 0.998). The dimensional error of forming the architecture was 1% as a coefficient of variation. Bone marrow-derived osteoblasts were cultured on a polished surface and on meso- and nano-scale hybrid textured surfaces with different spike heights. The osteoblastic differentiation was significantly promoted on the hybrid-textured surfaces compared with the polished surface, and among them the hybrid-textured surface with 40 μm-high spikes showed unparalleled performance. In vivo bone-implant integration also peaked when the hybrid-textured surface had 40 μm-high spikes. The relationships between the spike height and measures of osteoblast differentiation and the strength of bone and implant integration were non-linear. The controllable creation of meso- and nano-scale hybrid biomimetic surfaces established in this study may provide a novel technological platform and design strategy for future development of biomaterial surfaces to improve bone integration and regeneration.     

Exploring the Minimal RNA Substrate of Flexizymes

Flexizymes are tRNA acylation ribozymes that have been successfully used to facilitate genetic code reprogramming. They are capable of charging acid substrates onto various tRNAs and tRNA analogues. However, their minimal RNA substrate has not been investigated. Here we have designed fluorescently labeled short RNAs corresponding to the four, three, and two bases (4bRNA, 3bRNA, 2bRNA) at the tRNA 3′-end and explored the minimal RNA substrate of flexizymes, dFx and eFx. 3bRNA was the observed minimal RNA substrate of the flexizymes, but the efficiency of acylation of this short RNA was two to three times lower than that of 4bRNA. The efficiency of acylation of 4bRNA was comparable with that of the microhelix, a 22-base RNA conventionally used as a tRNA analogue for analyzing acylation efficiency. We also compared the efficiencies of acylation of the microhelix and 4bRNA with various acid substrates. Thanks to the short length of 4bRNA, its acyl-4bRNA products exhibited larger mobility shifts in gel electrophoresis than those exhibited by acyl-microhelix products with every substrate tested. This indicated that 4bRNA was an ideal RNA substrate for analyzing the efficiency of acylation by flexizymes.