Scanning ion conductance microscopy (SICM) using biological nanopores is a powerful analytical tool that can provide spatially resolved topography and chemical information. However, the low spatial resolution caused by the large tip diameter of the probe has limited the practical application of the SICM system. Although the tip-dip method has conventionally been used to form a lipid bilayer at the tip of pipettes, an alternative method to form the lipid bilayer is required because the lifetime of lipid bilayers formed by the tip-dip method is too short to map chemical information by stochastic nanopore sensing. Here, we propose a method to prepare lipid bilayers using a hydrogel-filled nanopipette. The lipid bilayer is formed at the tip of the pipette by inserting the pipette into a layered solution of an oil/lipid mixture and an aqueous electrolyte. Since the hydrogel supports the lipid bilayer, the lifetime of the lipid bilayers prepared by this method is improved over that formed by the tip-dip method. Furthermore, the hydrogel at the pore aperture reduces the translocation speed of analytes through nanopores, indicating that the hydrogel-filled nanopipette system can offer highly sensitive chemical sensing. Finally, we measure local single-strand deoxyribonucleic acid concentrations in the concentration gradient generated by a microhole using the biological nanopore probe. We believe that the SICM system using the hydrogel-filled nanopipette-based biological nanopore probe will offer a powerful analytical system for biological phenomena, including cell communication and signal transduction.
Growth analysis based on tree‐ring chronology is difficult in trees in aseasonal tropical rain forests, because annual growth rings may be unclear or completely absent. Fortunately, tree growth history recorded in xylem tissue is capable of providing valuable information on the responses of trees and forests to past and present environmental changes, including global warming.
We have developed a new technique for aseasonal tropical forest trees which derives their growth rates from xylem Δ14C, and verified its accuracy. We also determined, from xylem δ13C, the intrinsic water‐use efficiency (iWUE) in the past 50 years. We analysed changes in xylem Δ14C and δ13C in 23 canopy trees of 12 species in 6 families growing in Pasoh Forest Reserve, Malaysia; each stem diameter at breast height (DBH) was recorded 14 times from 1969 to 2011.
We found a significant positive relationship between the growth rates determined by 14C dating and the past DBH data. On the other hand, leaf‐internal CO2 (Ci) content did not change with increasing atmospheric CO2 (Ca). Thus, the iWUE increased significantly over the last 50 years in all the families and species tested.
This study showed that the simultaneous measurements of xylem Δ14C and δ13C could reveal a long‐term change in tree growth and iWUE during the past 50 years with high accuracy in various species and/or individuals in aseasonal tropical rainforests exhibiting high species diversity.
Straight-blade Darrieus vertical axis wind turbines are used as medium and small size wind turbine because of higher power output in vertical axis wind turbine (VAWT). In our previous study, the relationship between the performance and Reynolds number based on airfoil chord length had been investigated by using small-scale test models of lift-type VAWT, and the results showed that the performance of tested wind turbine models with small diameter was clearly lower than that of the large-scale field test machine, and its performance also varies significantly with the blade pitch angle. In this study, we focused on the performance of a small-scale straight-blade Darrieus VAWT, the relationship among the blade airfoil camber direction and the pitch angle, and the performance of the small-scale VAWT was examined experimentally by using a small-scale VAWT test model with Gurney flap which was a small flat plate. Gurney flaps with its height h, as a ratio to the blade chord length c, h/c = 0.036 to 0.055, were attached to the blades of the VAWT test model, in
Agglomeration resistant contact of NiSi2 with Ge substrates has been performed using stacked silicidation process. Stable Schottky barrier height at NiSi2/Ge interface with ideality factor of less than 1.2 can be maintained up to annealing temperature of 500 oC. Incorporation of P atom at NiSi2/Ge interface modulates the Schottky barrier height to produce Ohmic contact.
In the developments of the polymer membrane electrolyte fuel cells (PEMFCs), strategic design of their catalysts layer is a key to improve the efficiency and durability. Especially, interfacial structure of the electrode catalysts constructed by carbon support, platinum (Pt)-based nanoparticles and polymer electrolyte so called ionomer dominates the efficiency. It is known that the surface coverage of the ionomers onto the carbon-supported Pt nanoparticles generates overpotentials in the catalyst layer. To avoid this, an ionomer-free electrode catalyst is developed by functionalized surface of carbon supports, in which the support is covalently grafted to benzenesulfonic acid to facilitate the proton conduction on the carbon surface and Pt nanoparticles are attached to the acid-grafted carbon support. In single-cell measurements, although the ionomer-free electrode catalyst exhibits larger proton resistance than a conventional ionomer-based electrode catalyst, higher activity at low (< 0.01 mA cm−2) and high (>1.7 mA cm−2) current densities were achieved owing to increased oxygen reduction reaction activity and decreased oxygen diffusion resistance, respectively. Elimination of the ionomer reduces both the interfacial overpotential as well as diffusion overpotential of the oxygen.
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