Identification of factors that accelerate hydrogen production by Clostridium butyricum RAK25832 using casamino acids as a nitrogen source

The ability of Clostridium butyricum RAK25832 to use casamino acids as a nitrogen source was investigated. Strain RAK25832 showed the capacity to utilize different types of carbon sources. With glucose as a carbon source (10 g/L), the preferred final concentration of casamino acids was 26.67 g/L, with a cumulative hydrogen production, production rate, and yield of 2505 mL H₂/L, 160 mL/h, and 1.81 mol H₂/mol glucose, respectively. Eighteen metal elements were screened to identify the most important metals for biohydrogen production, and four elements were optimized. The optimal medium composition was MgCl₂·6H₂O (0.1 g/L), K₂HPO₄·3H₂O (6.67 g/L), NaHCO₃ (2.6 g/L), and FeCl₂·4H₂O (0.002 g/L). Vitamin supplementation of the medium showed no significant effect on hydrogen production. Under the optimized conditions, cumulative hydrogen production reached 3074 mL H₂/L. This is the first study to demonstrate the use of casamino acids as a nitrogen source by C. butyricum.     

Molecular Mechanisms for the Regulation of Insulin-Stimulated Glucose Uptake by Small Guanosine Triphosphatases in Skeletal Muscle and Adipocytes

Insulin is a hormone that regulates the blood glucose level by stimulating various physiological responses in its target tissues. In skeletal muscle and adipose tissue, insulin promotes membrane trafficking of the glucose transporter GLUT4 from GLUT4 storage vesicles to the plasma membrane, thereby facilitating the uptake of glucose from the circulation. Detailed mechanisms underlying insulin-dependent intracellular signal transduction for glucose uptake remain largely unknown. In this article, I give an overview on the recently identified signaling network involving Rab, Ras, and Rho family small guanosine triphosphatases (GTPases) that regulates glucose uptake in insulin-responsive tissues. In particular, the regulatory mechanisms for these small GTPases and the cross-talk between protein kinase and small GTPase cascades are highlighted.     

Why we talk?: altruism and multilevel selection in the origin of language

Talking entails costs of production and time, although some of the information sent to hearers will be of value to them in general. We believe that the matter of why we talk at all is a key question for the origin of language, and the answer will shed some light on the mystery of human identity. This article focuses on altruism in communication, and aims to demonstrate evolutionary scenarios based on multilevel selection. We constructed a computational model to examine these scenarios. The evolutionary experiments showed that in the case of an unstructured population, a linguistic system hardly emerged due to the dynamics between interpretable utterance that imposes a penalty and correct interpretation that yields a reward, which is similar to prey-predator dynamics. However, in the case of a multigroup population, a linguistic system emerged owing to multilevel selection among the groups. In addition, the probability of success in conversation was higher in a group in more severe environmental conditions. This result supports Bickerton’s hypothesis based on the ecological gap between human ancestors and other ape species.     

Performance evaluation of membrane on catalyst module for hydrogen production from natural gas

We have been developing a hydrogen production module with a Pd-based membrane on catalyst (MOC) from natural gas. The MOC module is expected to be more compact and cheaper than the conventional hydrogen production module. To evaluate the hydrogen production performance of the MOC module and to clear the factor that dominates the effective hydrogen production, we compared the reforming performance of the catalytic support without hydrogen permeable membrane and the MOC module at various reaction conditions. As a result, it was cleared that hydrogen permeation through the membrane improves the methane conversion drastically in the MOC module by comparing with the support only module and changing the experimental conditions.     

Evaluation of the reduction in CO2 emissions by applying Micro‐Grid to home energy supply system

Dispersed generators such as wind power systems, photovoltaic systems, and cogeneration systems are expected to mitigate the environmental burden of energy consumption, and their installation has been promoted recently. Micro‐Grid is focused on as a method to solve some problems in a commercial electric power line when installing a large number of dispersed generators, and some demonstrative research on Micro‐Grid for large‐scale systems is being carried out now. Also, small cogeneration systems for houses, such as gas engines and fuel cells, are expected to improve CO₂ emissions. However, if the power and heat demand of a family are relatively small or are unbalanced, the cogeneration system does not operate effectively. The authors have studied the application of Micro‐Grid for home energy supply, and have developed a control system to solve this problem. The system achieves a reduction of CO₂ emissions and energy costs by sharing electric power and heat among some houses with cogeneration systems. This paper presents an outline of the newly developed system, and in particular describes the effect of the reduction in CO₂ emissions compared with a conventional energy supply method, and the case in which dispersed generators are installed in some houses and operate independently. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(3): 19–27, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20879     

Fractionation and enrichment of CLA isomers by selective esterification with Candida rugosa lipase

A commercial product of CLA contains almost equal amounts of cis-9,trans-11 (c9,t11)-CLA and trans-10,cis-12 (t10,c12)-CLA. We attempted to enrich the two isomers by a two-step selective esterification using Candida rugosa lipase that acted on c9,t11-CLA more strongly than on t10,c12-CLA. An FFA mixture containing CLA isomers was esterified with an equimolar amount of lauryl alcohol in a mixture of 20% water and the lipase. When the esterification of total FA reached 50%, two isomers were fractionated in a good yield: t10,c12-CLA was enriched in FFA, and c9,t11-CLA was recovered in lauryl esters. The FFA were esterified again to enrich t10,c12-CLA. At 27.3% esterification of total FA, the t10,c12-CLA content in FFA increased to 64.8 wt% with 89.3% recovery: The ratio of the content of t10,c12-CLA to that of two isomers was 95.9%. Lauryl esters obtained by the single esterification were employed for enrichment of c9,t11-CLA. After the esters were hydrolyzed, the resulting FFA were esterified again with lauryl alcohol. At 62.0% esterification of total FA, the c9,t11-CLA content in lauryl esters increased to 73.3 wt% with 79.4% recovery: The ratio of the content of c9,t11-CLA to that of two isomers was 95.6%. In a 600-g-scale purification, molecular distillation was effective in separating the reaction mixture into lauryl alcohol, FFA, and lauryl ester fractions.     

Design and performance of high-precision MT-type connector for1.55-μm zero-dispersion-shifted fiber-ribbon cables

We have found that, for dispersion-shifted fiber (DSF) ribbons, the accuracy with which the fiberhole is positioned in the connector ferrule must be less than 0.6 μm to realize a low average insertion loss of about 0.1 dB. By using the high-precision ferrules, we realized MT-type connectors that achieved a very low average insertion loss of 0.11 dB with a maximum of 0.37 dB. These connectors also satisfied mechanical and environmental stability requirements. We have confirmed that our high-precision MT-type connectors can be used for joining DSF ribbon     

Managing networks of communities of practice for organizational knowledge creation A Knowledge Management imperative in the era of globalization

This article explores some imperatives of Knowledge Management for organizational knowledge creation in the era of globalization. As the transformation of Knowledge Management practices of Japanese firms in 1990s shows, Nonaka and TakeuchVs original model of organizational knowledge creation needs to be expanded by incorporating the concept of “community of practice” as the “engine” of knowledge creation. As an attempt for such expansion, it proposes a model of knowledge-creating organization as a self-organizing network of interactive, overlapping, and self-managing communities of practice. This article also explores some organizational conditions and managerial implications to prevent “malfunction” of communities of practice in the threats of globalization and to facilitate their dynamic evolution. Knowledge-creating organizations and their managers need to give due recognition to and support for “differences” that exist not only among diverse communities of practices but also within each communities. At a micro level approach, they need to “empower” community members by encouraging “ story-telling” or “narrative” of members’ lives in the communities and by assuring “transparency” of activities and resources to the members. As a macro level approach, they need to develop a “communitarian” organizational structure that fits to organizational knowledge creation in “multiculturalization” of societies.