Volatile Compounds and the Changes in Their Concentration Levels during Storage in Beers Containing Varying Malt Concentrations

ABSTRACT:  Volatile compounds in beers brewed with different amounts of malt were analyzed by using the stir bar sorptive extraction–gas chromatography-mass spectrometry method. We identified 90 compounds—25 esters, 17 terpenes, 14 alcohols, 11 acids, 6 furans, 6 aroma compounds, 5 carbonyls, and other compounds. An analysis of aged beer suggested that the concentration levels of stale flavor compounds—β-damascenone, γ-nonalactone, ethyl cinnamate, and 2-methoxy-4-vinylphenol—in nonmalt beer were different from those in all-malt and standard beer. Additionally, concentrations of these compounds did not increase during storage in most nonmalt beer analyzed in this study. Nerolidol may be a good marker candidate regardless of the malt content.     

Bifunctional Transition Metal-Based Molecular Catalysts for Asymmetric C–C and C–N Bond Formation

This paper describes recent advances in the development of the asymmetric catalytic reactions promoted by conceptually new bifunctional molecular catalysts. These reactions include the enantioselective Michael addition of 1,3-dicarbonyl compounds to cyclic enones and nitroalkenes, and the enantioselective direct amination of α-cyanoacetates to diazoesters. The nature of the catalyst in each particular case was delicately tuned by adjusting the combination of the central metal together with the structures of the cooperating ligands, applied solvents, and the reaction conditions to achieve the utmost catalytic performance in terms of reactivity and selectivity. In the presence of the optimized catalyst the addition reactions proceeded smoothly with a 1:1 M ratio of the reagents to give the corresponding chiral adducts with excellent yields and ee’s. Preliminary mechanistic studies based on NMR spectroscopy and DFT analysis showed that the key step of the catalytic cycle is the interaction of the bifunctional catalyst with a pronucleophilic reagent that leads to stereoselective formation of C-, O-, or N-bound amino complexes. The resulting amino catalyst bearing metal-bound nucleophiles readily reacts with an electrophile that acquires the reactive conformation through the cooperative effect of the acidic NH protons. This results in the formation of a C–C or a C–N bond yielding the corresponding products in a highly stereoselective manner.     

Pulse response measurement for locating water tree degradation in XLPE cables

Water treeing is a degradation mode of power cable with polymeric insulation. A water tree is composed of small droplets filled with water. As the conductivity in a water tree is very high, it leads to dielectric breakdown when it grows. Because the inside of the water tree is filled with trap sites, it is polarized with a certain distribution of relaxation time when a DC poling voltage is applied. Although its depolarization process after removing the poling voltage depends on the ambient temperature, applying a “depolarizing voltage” with the opposite polarity can accelerate the process. If a short pulse propagating through the cable is employed as a depolarization voltage, we may locate the water tree by looking at the time‐resolved pulse response. This would lead to a diagnosis method with spatial resolution. In order to retain 100‐m spatial resolution, the response should be as sharp as 1 μs. As a preliminary study, a coaxial communication cable was aged to form water trees. A DC poling voltage was applied followed by a pulse voltage with opposite polarity. The rise time of the pulse was several hundreds of microseconds. A sharp pulse current response 50 μs wide was observed, suggesting that rapid depolarization took place. No such response was seen when the cable specimen was not aged. We concluded that the technique is quite feasible. Because the response was found to be as quick as several microseconds, an experiment using a cable 405 m long with 5 m of degraded length in the middle was performed. It was shown that the degraded point was successfully located. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(3): 18–24, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21294     

Rhythmic behavior of social insects from single to multibody

Revealing the evolution of well-organized social behavior requires understanding a mechanism by which collective behavior is produced. A well-organized group may be produced by two possible mechanisms, namely, a central control and a distributed control. In the second case, local interactions between interchangeable components function at the bottom of the collective behavior. We focused on a simple behavior of an individual ant and analyzed the interactions between a pair of ants. In an experimental set-up, we placed the workers in a hemisphere without a nest, food, and a queen, and recorded their trajectories. The temporal pattern of velocity of each ant was obtained. From this bottom-up approach, we found the characteristic behavior of a single worker and a pair of workers as follows: (1) Activity of each individual has a rhythmic component. (2) Interactions between a pair of individuals result in two types of coupling, namely the anti-phase and the in-phase coupling. The direct physical contacts between the pair of workers might cause a phase shift of the rhythmic components in individual ants. We also build up a simple model based on the coupled oscillators toward the understanding of the whole colony behavior.     

Air-stable triarylamine-based amorphous polymer as donor material for bulk-heterojunction organic solar cells

A new air-stable triarylamine-based amorphous polymer, TSP-T11, which consists of thiophene and triarylamine units, can be successfully utilized to fabricate bulk-heterojunction organic photovoltaics (OPVs) using PC₆₀BM or PC₇₀BM as acceptor materials. The highest level of performance of OPVs optimized at TSP-T11:PC₇₀BM (weight ratios of 1:4) with thicknesses of 68 nm exhibited an open circuit voltage (V_oc) of 0.75 V, a short circuit current (J_sc) of 8.03 mA cm⁻², and a power-conversion efficiency (PCE) of 2.22% under simulated air mass 1.5 solar irradiation at 100 mW cm⁻². Although TSP-T11 has a lower hole mobility (1.5×10⁻⁴ cm² V⁻¹ s⁻¹) than P3HT, the use of amorphous film of TSP-T11 as a donor material for OPVs offers advantages over the use of polycrystalline film of P3HT in terms of its air-stability and pinhole-free homogeneous morphology.     

Independent Reinforced Soil Structure with Pile Foundation—Piled Geo-Wall: An Experimental Study on the Application to Seismic Measure for Embankment—

Our aim in this study was to achieve an independent reinforced soil structure with pile foundation that can be applied to such structures as earth retaining walls and countermeasures against the collapse of embankments or rockfall impact built on narrow construction sites, such as on slopes. In order to confirm the effectiveness of the application of pile foundation to reinforced soil structures by geogrid for improvement of the lateral resistance of the structure and to investigate the interaction between pile and reinforced soil structure, a dynamic centrifuge model test (25 G) was carried out. Two geogrid reinforced soil, one with piles and one without, were used in a countermeasure to reduce the deformation of a road embankment built on a slope in the event of an earthquake, and the effectiveness of the pile foundation to the reinforced soil structure was considered with regard to it affected the road surface. The details and the results of the dynamic centrifuge model test, as well as the interaction between pile and reinforced soil structure are described, and the effectiveness of the application of pile foundation to reinforced soil structure is discussed in this paper.     

An analysis of interactive influences in Mazda’s Yokokai Keiretsu

In a keiretsu, i.e., a set of companies with interlocking business relationships, it is important for corporate management to identify those companies over which they reciprocally exercise greater influence and power. In this article we employ a DEcision MAking Trial and Evaluation Laboratory (DEMATEL) to illustrate the reciprocal influence of each company in Mazda’s Yokokai keiretsu, as measured by the number of transactions and cross-shareholdings. Furthermore, we calculate the centrality index of each company, and then analyze the relationship between centrality index and influence in order to identify the determinants of the influence. Based on the findings, we identify some characteristics of effective relationships which have important managerial implications.     

Fracture of sustained tensile-loaded Sn–3.0Ag–0.5Cu solder alloy in NaCl solution

The fracture of Sn–3.0Ag–0.5Cu solder alloy has been investigated by a constant sustained tensile-loading test in 0.9 wt.% NaCl aqueous solution at room temperature. Under applied stress in the solution, many cracks nucleate and propagate on the side surface of the specimen. The fracture is not an ordinary creep rupture mode and is probably caused by the decrease in cross section of the specimen due to crack propagation. The preferential dissolution of Ag and Cu ions is clearly observed under applied stress in the solution. The time to fracture and the critical stress for fracture in the solution are lower than those in the atmosphere. The present results indicate that the reliability of lead-free solder alloys must be evaluated considering the effects of the combination of environment and applied stress.     

Screening and Analysis of Spices with Ability to Suppress Verocytotoxin Production by Escherichia coli O157

ABSTRACT:  To reduce the amounts of verocytotoxin (VT) produced by  Escherichia coli  O157:H7, various spices were screened for their ability to suppress VT production. Extracts of these spices were prepared with 70% ethyl alcohol. When  E. coli  O157:H7 cells were grown to the stationary phase at 37 °C in Luria-Bertani medium supplemented with 0.02% allspice extract, the production of both VT1 and VT2 was significantly reduced. Neither growth inhibition nor a delay in the lag phase was observed when the cells were cultured in the presence of 0.02% allspice extract. An active component of the allspice extract was purified by HPLC and was identified as eugenol. When we examined the suppressive effect of eugenol on VT production by  E. coli  O157:H7, the amounts of both intracellular and extracellular VTs were found to decrease with an increase in eugenol concentration. Our results suggest that eugenol is useful for reducing the virulence of  E. coli  O157:H7.