Atomically resolved imaging by low-temperature frequency-modulation atomic force microscopy using a quartz length-extension resonator

Low-temperature ultrahigh vacuum frequency-modulation atomic force microscopy (AFM) was performed using a 1 MHz length-extension type of quartz resonator as a force sensor. Taking advantage of the high stiffness of the resonator, the AFM was operated with an oscillation amplitude smaller than 100 pm, which is favorable for high spatial resolution, without snapping an AFM tip onto a sample surface. Atomically resolved imaging of the adatom structure on the Si(111)-(7x7) surface was successfully obtained.     

Dynamic simulation of wire rope with contact

We present a dynamic simulation of a wire rope involving both contacts with a winch drum and hydraulic systems using the finite element method. Rapid winch operation often causes disorderly winding of the wire rope, which is an important quality problem. Dynamic simulation is, therefore, required for design of the hydraulic winch system on construction machinery. The wire rope is modeled using by truss elements considering large displacement motion. The contact between the wire rope and the winch drum is modeled using by variable-length truss elements and bilinear spring elements. An improved Newton method is proposed for nonlinear dynamic analysis. Simulation results show that some lever operations result in rope looseness and intense pressure fluctuation. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Etsujiro Imanishi received his master degree in Mechanical Engineering from Ritsumeikan University, in 1981. He is working for KOBE STEEL, LTD. since 1981. He received his doctor degree in 1992. Dr. Imanishi’s research interests include dynamics of construction machinery, numerical analysis and multibody dynamics.     

Separation–permeation performance of porous Si3N4 ceramics composed of columnar β-Si3N4 grains as membrane filters for microfiltration

The separation–permeation performance of porous silicon nitride (Si₃N₄) ceramics (consisting of columnar grains connected at random in three dimensions) as membrane filters was evaluated, and compared with commercial Al₂O₃ membranes having a three-layer structure. Si₃N₄ membranes separate particles with diameters much less than their pore diameters. The permeability of Si₃N₄ membranes with separability values the same as those of the Al₂O₃ membranes was about 1.3–2.4 times as large as the Al₂O₃ membranes. Dead-end filtration examination, using Al₂O₃ particles with a particle size distribution, indicated that the Si₃N₄ membrane filtration mechanism obeyed the cake filtration mechanism although the particle size was smaller than the pore size of the Si₃N₄ membranes.     

Production of hydrogen peroxide by a small molecular mass compound in milk from Holstein cows with high and low milk somatic cell count

Mastitis is the most frequent and prevalent production disease in dairy herds in developed countries. Based on a milk somatic cell count (SCC) of either >300,000 or <200,000 cells/ml in this study, we defined the quarter as either inflamed or uninflamed, respectively. The electrical conductivity (EC) of milk was used as an indicator of udder epithelial cell damage. We determined the amount of H2O2 produced by utilizing a small molecular weight compound in milk, and examined the characteristics of H2O2 production and EC in milk from inflamed and uninflamed quarters. In cows with milk of delivery grade (control population), H2O2 production and EC were 3.6+/-1.3 nmol/ml and 5.4+/-0.4 mS/cm (mean+/-sd), respectively. In 37 inflamed quarter milk samples, the production of H2O2 was 1.9+/-1.0 nmol/ml and was significantly smaller than that in the control population (P<0.01). Production of H2O2 was moderately but significantly correlated with EC (r<-0.71). In 20 cows with inflamed quarters, the production of H2O2 in milk from inflamed quarters was significantly smaller than that in milk from uninflamed quarters (P<0.01). In 18 out of 20 cows, milk from inflamed quarters showed the smallest H2O2 production among all tested quarters in each cow. We conclude that inflammation caused a decrease in H2O2 production in milk. In this study, we present parameters for evaluating the lactoperoxidase/H2O2/thiocyanate antibacterial defence system in bovine milk.     

Dispersion in active transport by kinesin-powered molecular shuttles

Active transport driven by molecular motors is a key technology for the continued miniaturization of lab-on-a-chip devices, because it is expected to enable nanofluidic devices with channel diameters of less than 1 microm and total channel lengths on the order of 1 mm. An important metric for a transport mechanism employed in an analytic device is dispersion, because it critically affects the sensitivity and resolution. Here, we investigate the mechanisms responsible for the dispersion of a swarm of "molecular shuttles", consisting of functionalized microtubules propelled by surface-adhered kinesin motor proteins. Using a simple model and measurements of the path persistence length, motional diffusion coefficient, and the distribution of average velocities, we found that, at the time scale relevant in the envisioned nanobiodevices, variations in the time-averaged velocities between shuttles will make a stronger contribution to the dispersion of the swarm than both the fluctuations around the time-averaged velocity of an individual shuttle and the fluctuations in path length due to wiggling within the channel. Overall, the dispersion of such molecular shuttles is comparable to the dispersion of a sample plug transported by electroosmotic flow.     

Simultaneous achievement of driver assistance and skill development in shared and cooperative controls

Cognition, Technology & Work - Advanced driver-assistance systems have successfully reduced drivers’ workloads and increased safety. On the other hand, the excessive use of such systems...     

Applications of microstructures fabricated by proton beam writing to electric-micro filters

Fabrication of high-aspect-ratio microstructures was performed by proton beam writing (PBW) using a microbeam line at Takasaki Ion Accelerators for Advanced Radiation Application (TIARA), JAEA Takasaki, JAPAN. As one of the applications of the high-aspect-ratio structures micro-machined by PBW, we utilized the high-aspect pillars for electric-micro filters of microbes such as Escherichia coli and Yeast based on the dielectrophoretic force. The filter is equipped with high-aspect pillars with a height of ～20 μm and a diameter of ～1 μm on a glass plate. Evaluation of the dielectrophoresis (DEP) device for capturing E. coli and Yeast was made using either observation by optical microscope or photoluminescence (PL) measurements.     

Fabrication of porous SiC ceramics having pores shaped with Si grain templates

SiC porous ceramics were prepared by heating mixtures of Si powder and carbon black at 900 °C for 24 h in Na vapor. The grains of the Si powder were not only the source of Si for SiC but also served as templates for the pores in the SiC porous ceramics. Angular-shaped pores with sizes of 2-10, 10-150 and 50-150 μm were formed by angular Si grains with sizes of ≤10, ≤50 and ≤150 μm, respectively. The porosity of the SiC porous ceramics was around 55-59%. Spherical pores were also formed when spherical Si grains were used. A bending strength of 14 MPa was measured for the SiC porous ceramics prepared with the Si grains (≤50 μm).