A biochemical sniffer-chip for convenient analysis of gaseous formaldehyde from timber materials

A biochemical gas-sensor (sniffer-chip) with formaldehyde dehydrogenase (FALDH) was developed for convenient analysis of gaseous formaldehyde with high gas-selectivity. The sniffer-chip for formaldehyde in the gas phase was constructed by immobilizing FALDH to a Pt-electrode coated hydrophilic PTFE membrane. The oxidation current of NADH produced by the enzymatic reactions was measured by amperometric analysis. The calibration range of the sniffer-chip for formaldehyde in the gas phase was from 40 to 2000 ppb, which encountered the maximum permissible concentration of formaldehyde vapor in the residential house (80 ppb) and formaldehyde detection limit for the human sense of smell (410 ppb). As the resident-environmental application, the sniffer-chip was possible to measure the formaldehyde concentration from some timber materials (3 kinds of interior timber and 2 kinds of exterior formwork timber) within 3 min. The calculated concentration value by a regression analysis was consistent with those of a commercially available gas sensor and a gas detector tube for formaldehyde. The FALDH sniffer-tip would be effective and convenient approach to detect and measure gaseous formaldehyde with high gas-selectivity at the residential atmosphere. Correspondence: Kohji Mitsubayashi, Department of Biomedical Devices and Instrumentation, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062, Japan     

Coevolution of role preference and fairness in the ultimatum game

Traditional economics assumes that humans are rational. However, it is known that humans behave fairly in the ultimatum game (UG). There are various explanations for this apparent paradox, such as the “inequity aversion.” However, the role preference (proposer or responder) of humans in the UG is obscure. I conducted a UG scenario experiment where subjects were asked their role preference in addition to their decision in the game. The results showed that the subjects prefer to be proposers rather than responders. In particular, it was found that rational subjects had a high preference for the proposer role. On the basis of these results, I conducted evolutionary simulations of the UG, where each individual has role preference intensity. A role is allocated to the individual proportional to the preference intensity. The results showed coevolution of role preference and fairness. The preference for the proposer role evolved when rational strategy evolved, whereas this preference weakened as rationality decreased. This indicates that fairness has a strong link with role preference; in other words, human fairness is always threatened by the “power and position” of some particular individuals. Hence, its equal distribution among individuals may be effective in maintaining a high level of fairness. © 2012 Wiley Periodicals, Inc. Complexity, 2012     

Reforming of Carbon Dioxide to Methane and Methanol by Electric Impulse Low-Pressure Discharge with Hydrogen

Basic phenomena of the reduction of carbon dioxide to reusable organic materials including methane and methanol were investigated by using a radio frequency impulse discharge in a low gas pressure range without catalysis. The discharge took place under different discharge parameters such as voltage, gas flow rate, gas-mixing ratio, and gas residence time, where the carbon dioxide was mixed with hydrogen at total gas pressure of 1–10 Torr. Organic materials such as methane and methanol were observed. Carbon monoxide was a major product from carbon dioxide. Methane was the dominant organic species produced by the discharge. The concentration of methane increased with discharge voltage, and its volume fraction attained 10–20% of the products containing carbon that came from carbon dioxide. This fraction was also dependent on the mixing ratio of carbon dioxide and hydrogen. We also observed the formation of methanol, though its fraction was low, a few %, compared with methane.     

In-situ measurement of molecular orientation of the pentacene ultrathin films grown on SiO2 substrates

Molecular orientations of pentacene ultrathin films grown on SiO₂ substrates were studied without the influence of the atmosphere by vacuum atomic force microscopy (V-AFM) and near edge X-ray absorption fine structure (NEXAFS). The experimental processes from deposition of pentacene to characterization of films were performed under vacuum condition without exposure to the atmosphere. V-AFM and NEXAFS measurements showed that pentacene molecules tend to grow on SiO₂ surface with their molecular long axes perpendicular to the substrate surfaces (standing-mode) irrespective of preparation procedure of SiO₂ substrate.     

Stereoselective total synthesis of acremomannolipin A and its anomer,the potent calcium signal modulators with a novel glycolipid structure: role of the stereochemistry at the anomeric center on the activity

A full account of stereoselective total synthesis of a novel glycolipid, acremomannolipin A (1), the potent calcium signal modulator isolated from Acremonium strictum, by employing the stereoselective β-mannosylation of 4,6-O-benzylidene-protected mannosyl sulfoxide with d-mannitol as the key reaction is described. The α-anomer (epi-1) of 1 was also synthesized selectively. The calcium modulating activity was reduced upon inversion of the configuration at the anomeric center, indicating that the β-configuration of the mannose moiety is preferable for the activity.     

Diesel Soot Combustion over Mn2O3 Catalysts with Different Morphologies: Elucidating the Role of Active Oxygen Species in Soot Combustion

Catalytic diesel soot combustion was examined using a series of Mn₂O₃ catalysts with different morphologies, including plate, prism, hollow spheres and powders. The plate‐shaped Mn₂O₃ (Mn₂O₃‐plate) exhibited superior carbon soot combustion activity compared to the prism‐shaped, hollow‐structured and powdery Mn₂O₃ under both tight and loose contact modes at soot combustion temperatures (T₅₀) of 327 °C and 457 °C, respectively. Comprehensive characterization studies using scanning electron microscopy, scanning transmission electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, temperature‐programmed reduction and oxygen release measurements, revealed that the improved activity of Mn₂O₃‐plate was mainly attributed to the high oxygen release rate of surface‐adsorbed active oxygen species, which originated from oxygen vacancy sites introduced during the catalyst preparation, rather than specific surface‐exposed planes. The study provides new insights for the design and synthesis of efficient oxidation catalysts for carbon soot combustion as well as for other oxidation reactions of harmful hydrocarbon compounds.     

In-situ observation of graphene growth on Ni(111)

Graphene growth of mono-, bi- and tri-layers on Ni(111) through surface segregation was observed in situ by low energy electron microscopy. The carbon segregation was controlled by adjusting substrate temperature from 1200 K to 1050 K. After the completion of the first layer at 1125 K, the second layer grew at the interface between the first-layer and the substrate at 1050 K. The third layer also started to grow at the same temperature, 1050 K. All the layers exhibited a 1 × 1 atomic structure. The edges of the first-layer islands were straight lines, reflecting the hexagonal atomic structure. On the other hand, the shapes of the second-layer islands were dendritic. The edges of the third-layer islands were again straight lines similar to those of the first-layer islands. The phenomena presumably originate from the changes of interfacial-bond strength of the graphene to Ni substrate depending on the graphene thickness. No nucleation site of graphene layers was directly observed. All the layers expanded out of the field of view and covered the surface. The number of nucleation sites is extremely small on Ni(111) surface. This finding might open the way to grow the high quality, single-domain graphene crystals.     

Free Mesh Method: fundamental conception, algorithms and accuracy study

The finite element method (FEM) has been commonly employed in a variety of fields as a computer simulation method to solve such problems as solid, fluid, electro-magnetic phenomena and so on. However, creation of a quality mesh for the problem domain is a prerequisite when using FEM, which becomes a major part of the cost of a simulation. It is natural that the concept of meshless method has evolved. The free mesh method (FMM) is among the typical meshless methods intended for particle-like finite element analysis of problems that are difficult to handle using global mesh generation, especially on parallel processors. FMM is an efficient node-based finite element method that employs a local mesh generation technique and a node-by-node algorithm for the finite element calculations. In this paper, FMM and its variation are reviewed focusing on their fundamental conception, algorithms and accuracy.     

Sr substitution effects on atomic and local electronic structure of Ca2AlMnO5+δ

We performed the first-principle calculations based on spin-polarized density functional theory to investigate the Sr substitution effects on the atomic and local electronic structure of Ca₂AlMnO_5+δ. The ionic radius of Sr²⁺ is larger than that of Ca²⁺; thus, the lattice expansion occurs with Sr substitution. From the total energy calculations, we found that Sr substitution makes the oxygen-absorbed phase unstable and realizes the lower operation temperature. From the point of atomic structure, Sr substitution lengthens the bond length between Mn and O atoms connecting Mn and Al atoms in Al tetrahedral (O_Mn-Alt) in oxygen-absorbed phase, because the large Sr²⁺ prevents the release of the Jahn-Teller distortion. We also found that the covalent bonding between Mn and O_Mn-Alt atoms weaken with Sr substitution by the local electronic structure analysis, which results in the unstable oxygen-absorbed phase and weak prepeak and main peak intensity near the onset of O-K edge ELNES of O_Mn-Alt atoms.     

Metal-induced gap states at well defined alkali-halide/metal interfaces

In order to search for states specific to insulator/metal interfaces, we have studied epitaxially grown interfaces with element-selective near edge x-ray absorption fine structure. An extra peak is observed below the bulk edge onset for LiCl films on Cu and Ag substrates. The nature of chemical bonds as probed by x-ray photoemission spectroscopy and Auger electron spectroscopy remains unchanged, so we regard this as evidence for metal-induced gap states (MIGS) formed by the proximity to a metal, rather than local bonds at the interface. The dependence on the film thickness shows that the MIGS are as thin as one monolayer. An ab initio electronic structure calculation supports the existence of the MIGS that are strongly localized at the interface.