Atom-selective imaging and mechanical atom manipulation using the non-contact atomic force microscope

We succeeded in distinguishing between oxygen and silicon atoms on an oxygen-adsorbed Si(111)7 x 7 surface, and also distinguished between silicon and tin atoms on Si(111)7 x 7-Sn intermixed and Si(111) square root(3) x square root(3)-Sn mosaic-phase surfaces using non-contact atomic force microscopy (NC-AFM) at room temperature. Atom species of individual atoms are specified from the number of each atom in NC-AFM images, the tip-sample distance dependence of NC-AFM images and/or the surface distribution of each atom. Further, based on the NC-AFM method but using soft nanoindentation, we achieved two kinds of mechanical vertical manipulation of individual atoms: removal of a selected Si adatom and deposition of a Si atom into a selected Si adatom vacancy on the Si(111)7 x 7 surface at 78 K. Here, we carefully and slowly indented a Si atom on top of a clean Si tip apex onto a predetermined Si adatom to remove the targeted Si adatom and onto a predetermined Si adatom vacancy to deposit a Si atom, i.e. to repair the targeted Si adatom vacancy. By combining the atom-selective imaging method with two kinds of mechanical atom manipulation, i.e. by picking up a selected atom species and by depositing that atom one by one at the assigned site, we hope to construct nanomaterials and nanodevices made from more than two kinds of atom species in the near future.     

MicroRNAs in Salivary Exosome as Potential Biomarkers of Aging

The aim of this study was to examine whether salivary exosomal miRNAs could be identified as aging biomarkers. Fifteen young healthy volunteers (median age, 21.0 years) and 13 old individuals (median age, 66.0 years) were recruited. Unstimulated whole saliva was collected, salivary exosomes were isolated, and total RNA was extracted. In a microarray, 242 miRNAs were commonly detected in these two mixed samples. Based on the cut-off values of 2- or 0.5-fold changes (FC) and regulatory power for aging process, six candidate miRNAs (miR-24-3p, miR-371a-5p, miR-3175, miR-3162-5p, miR-671-5p, and miR-4667-5p) were selected. After comparing each total RNA obtained by the 15 young and 13 old individuals to validate the FC values using quantitative real-time PCR, miR-24-3p was identified as a novel candidate aging biomarker. This pilot study suggested that salivary exosomal miRNAs could be identified as candidate aging biomarkers. To confirm whether miR-24-3p in salivary exosomes are suitable biomarkers of aging, further validation research is required.     

Net energy analysis of bioethanol production system from high-yield rice plant in Japan

This study analyzes the energy balance of a bioethanol production system from high-yield rice plant in Japan. Two systems are considered in which rice is converted to ethanol: one in which cellulose feedstocks, straw and husk, are used for cogeneration (scenario 1), and the other in which they are converted to ethanol, and byproducts such as lignin and unreacted holocellulose are used for cogeneration (scenario 2). Energy input in the agricultural process including transportation is estimated to be 52.3 GJ/ha from an Input Output Table. The heating values of produced rice and cellulose feedstocks are 120.7 GJ/ha and 162.3 GJ/ha, respectively. The net energy balance (NEB) of scenario 1 is 129.2 GJ/ha, which produces 3.6 kL/ha of ethanol and 9420 kWh/ha of external electricity. On the other hand, NEB of scenario 1 is 11.7 GJ/ha, which produces 7.1 kL/ha of ethanol. Both NEBs are positive, but NEB of scenario 2 is much higher than that of scenario 1. An acid hydrolysis technology of cellulosic biomass applied to scenario 2 needs a large amount of heat energy for sulfuric acid recovery. If an enzyme hydrolysis of cellulosic biomass is developed, there is a possibility of improving NEB of scenario 2.     

Selective retrieval of microparticles in microchambers using electrolytically generated bubbles for cell array applications

This paper describes a method for the selective retrieval of microparticles using bubbles generated by electrolysis. Microparticles (polystyrene beads, mouse embryos, and cell spheroids) were arrayed in microchambers fabricated in SU-8 on the surface of an electrode consisting of indium tin oxide (ITO) patterned on glass. Bubbles were selectively generated in a target microchamber by applying a voltage to electrodes positioned in the microchamber. As a result, we successfully retrieved microparticles (100 μm in diameter) positioned in the microchambers. This method is gentle enough to maintain cellular viability, and therefore, it will be a powerful tool for the quantitative analysis of cells in an arrayed system.     

Optimizing service restoration in distribution systems based on scheduling of crews considering priorities of loads

The service restoration to sound sections within a short period as much as possible, performed after the permanent fault occurs in a distribution system, is significant for maintaining power supply reliability. This paper proposes an efficient method to find service restoration procedures based on fault searching and the optimal work scheduling of crews, considering the power supply priorities of loads and the probability of occurrence of faults. The proposed method is composed of two-stage problems to reduce the outage sections efficiently: (i) the problem to find a series of searching procedures for unknown fault locations in the first stage and (ii) the optimization problem of work schedules of crews in the second stage. In the first stage, the order of operation of switches opened for searching for the fault direction is determined, constituting the searching tree. After that, the proposed optimization method can efficiently solve the work scheduling problem by formulating it as a mixed-integer linear programming problem in the second stage. The computational experiments using a large-scale distribution system model with many remote and manual switches show that the proposed method can provide efficient service restoration procedures within a reasonable computational time.     

Moment performance of photovoltaic/thermal hybrid panel (numerical analysis and exergetic evaluation)

A photovoltaic/thermal hybrid panel (PV/T) is a high‐efficiency energy converter which supplies electrical energy and thermal energy from solar energy. In this paper, we report characteristics of two PV/T types under various environmental conditions and fluid flow rates, using numerical analysis. We found photovoltaic efficiencies to be 9.61% for PV/T_A and 10.56% for PV/T_B at T _c = 25 °C; thermal ones were 52.11% for PV/T_A and 40.14% for PV/T_B at T_f = 40 °C, I_rr = 800 W/m². From these results, we propose some design points to construct the optimum structure of PV/T. Next, we adopted exergetic evaluation to study electrical energy and thermal energy quantitatively. As a result, we could confirm the existence of flow rate maximizing the total efficiency (optimum flow rate) on some environmental condition, and could define the optimum operating condition. Moreover, we compare exergetic efficiencies on optimum operating conditions (maximum exergetic efficiency) under various environmental conditions with PV, PV/T_A, and PV/T_B. A rise of maximum exergetic efficiency with increasing irradiance yielded –3.6%/kW ⋅ m^–2, +3.6%/kW ⋅ m², and +1.4%/kW ⋅ m², respectively. Nevertheless, we could confirm a hybridizing advantage of high irradiance. © 2000 Scripta Technica, Electr Eng Jpn, 133(2): 43–51, 2000     

Interactive effects of milk basic protein supplements and habitual physical activity on bone health in older women: A 1-year randomized controlled trial

A 1-year randomized controlled trial examined effects of milk basic protein (MBP) supplementation (40 mg day^?1) and daily physical activity (step count and duration of exercise > 3 metabolic equivalents [METs]) on bone metabolism, forearm bone mineral density (BMD) and a calcaneal osteosonic index (OSI) in 79 females aged 65–86 years. MBP did not affect osteocalcin or bone-specific alkaline phosphatase, but at 12 months, excretion of deoxypyridinoline and cross-linked N-teleopeptides of type I collagen (NTx) were significantly less than in controls. Experimental subjects also maintained BMD and had a 1.5% increase of OSI at 12 months. After adjustments for age and baseline bone parameters, osteocalcin, deoxypyridinoline, NTx and/or OSI at 12 months were significantly related to step count and/or duration of activity > 3 METs. MBP reduced markers of bone loss, particularly in the lower extremities. Reduced resorption of bone was also associated with moderate-intensity/duration exercise, MBP therapy interacting significantly with habitual physical activity.     

Quantitative evaluation of the displacement distribution and stress intensity factor of fatigue cracks healed by a controlled high‐density electric current field

Fatigue cracks were healed by controlling a high‐density electric current. The changes in the displacement distribution around the crack tip and the stress intensity factor before and after crack healing were evaluated quantitatively with a digital image collation method. According to the results, it was determined that the cracks were closed by approximately 2 to 7 µm in this study. On the other hand, the stress intensity factor decreased or increased depending on the conditions of the crack and the current applied. The physical restriction between the crack surfaces, such as bridging, is important with respect to lowering the stress intensity factor after healing.     

Applicability of molten carbonate fuel cells to various fuels

MCFCs can utilize CO rich and H₂ lean fuel, such as gasified biomass or gasified waste as a Pt catalyst is not used and Pt poisoning by CO does not occur. This feature has become very important due to the worldwide CO₂ depression requirements. CRIEPI has developed MCFC technologies in line with a governmental program, which mainly focused on natural gas fuel. However, CRIEPI has recently been focussing on technologies for various fuel applications. Single cells and stacks were tested with various gas compositions and showed stable performance even with high CO and high fuel utilization conditions. Gasified biomass or waste can contain many kinds of impurities such as H₂S, HCl, HF, NH₃, etc. The effects of these impurities were taken into account for single cells, and the permissible limits were estimated.     

Ray-tracing method for isotropic inhomogeneous refractive-index media from arbitrary discrete input

We have developed a ray-tracing simulation procedure for optically isotropic gradient refractive-index media. The procedure can take discrete points of arbitrary distribution for the definition of refractive-index distributions and lens surfaces. It is useful for simulating ray trajectories in real lens systems. The procedure is applied to a ray-tracing simulation of the Luneburg lens and a radial gradient optical fiber. The simulation results are compared with the analytical solutions, and it is shown that they are in precise agreement.