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We designed and synthesized new atpenin A5 analogs for SAR study. Most of the analogs lacked one or several functional groups in the side chain of atpenin A5, and the stereoisomers proved to be weak nematode complex II inhibitors. However, we determined that 4-epi-atpenin A5 was a potent nematode complex II inhibitor comparable to atpenin A5. Therefore, 4-epi-atpenin A5 is expected to become a new lead compound in nematicide development.

The stereoselective total synthesis of atpenins A4 (2) and B (3), harzianopyridone (4), and NBRI23477 B (5) have been developed using a convergent approach involving the coupling reaction of a common iodopyridine with an aldehyde corresponding to the appropriate side chain of the desired compound. Furthermore, the absolute configurations of atpenin B (3), harzianopyridone (4), and NBRI23477 B (5) have been unambiguously determined.

The total synthesis of salinosporamide A has been achieved through enzymatic desymmetrization, diastereoselective aldol reaction, intramolecular aldol reaction, and intermolecular Reformatsky-type reaction followed by 1,4-reduction as key reactions.

Using a convergent approach involving the coupling reaction of a common iodopyridine with an aldehyde to the appropriate side chain, the stereoselective synthesis of atpenins A4 (Ia) and B (Ib), NBRI23477 B (Ic), and harzianopyridinone (II) is developed.

Enantioselective total synthesis of atpenin A5, a potent mitochondrial complex II (succinate-ubiquinone oxidoreductase) inhibitor, has been achieved by a convergent approach through a coupling reaction between 5-iodo-2,3,4,6-tetraalkoxypyridine and a side-chain aldehyde. The two key segments were synthesized through ortho-metalation/boronation with (MeO)3B/oxidation with mCPBA, ortho-iodination, halogen dance reaction, Sharpless epoxidation and regioselective epoxide-opening reaction. This synthetic study resulted in the revision of the earlier reported 1H-NMR data of the natural atpenin A5 and the confirmation of the stereochemical assignment.

Enantioselective total synthesis of atpenin A5, a potent mitochondrial complex II (succinate-ubiquinone oxidoreductase) inhibitor, has been achieved by a convergent approach through a coupling reaction between 5-iodo-2,3,4,6-tetraalkoxypyridine and a side-chain aldehyde. The two key segments were synthesized through ortho-metalation/boronation with (MeO)3B/oxidation with mCPBA, ortho-iodination, halogen dance reaction, Sharpless epoxidation and regioselective epoxide-opening reaction. This synthetic study resulted in the revision of the earlier reported 1H-NMR data of the natural atpenin A5 and the confirmation of the stereochemical assignment.

The total synthesis of salinosporamide A has been achieved through enzymatic desymmetrization, diastereoselective aldol reaction, intramolecular aldol reaction, and intermolecular Reformatsky-type reaction followed by 1,4-reduction as key reactions.

In this paper, a variety of link mining methods are handled in an integrated manner with previous data mining methods, and a network mining framework (NMF) is proposed. This paper also presents example usages of the NMF, and discusses how high-level network mining are achieved by using the NMF.

In this paper, we propose a novel communication paradigm called group-oriented communication. Different from conventional unicast-based communications, group-oriented communication is entirely based on group-based communication. Our group-oriented communication is essentially a type of many-to- many communication, but it realizes any type of communications including one-to-one, one-to-many, many-to-one and many-to- many communications based on group-based communication. With our group-oriented communication, diverse social activities can be shifted into a communication network in a straightforward way, and users' requirements on security/reliability can be fulfilled. In this paper, we first qualitatively discuss advantages of our group-oriented communication by comparing with the conventional IP-based network. We then discuss four design goals of a network architecture for our group-oriented communication: supporting dynamic entity/group, supporting address operation expression, realization of entity/group find ability, and realization of security. After carefully examining these design goals, we design a network architecture for realizing our group-oriented communication. Through quantitative evaluations, we show that the network architecture for our group-oriented communication should be packet-based, that reachability control is the core networking technology, and that the network architecture should have the two-layer structure consisting of transport and control layers.

In this paper, we propose a recursive estimation method of node characteristics called RENC (recursive estimation of node characteristics) using the topological structure of a complex networks. RENC reduces the effect of noise by recursively estimating node characteristics using the topological structure of a network. In this paper, we also propose a network generation model called LRE (linkage with relative evaluation). The network generation model LRE is for simulating a social network, in which every node is likely to make decision based on relative evaluation, so that it can reproduce several characteristics of a social network. In this paper, we evaluate the effectiveness of our recursive estimation method RENC by applying RENC to several networks generated with LRE. Consequently, we show that the estimation accuracy of node characteristics can be improved by using our recursive estimation method RENC.

In this paper, we propose a network architecture for realizing a group-based communication to solve issues of the Internet such as lack of security and low information S/N (Signal To Noise) ratio. We design a network architecture based on a multiple-association model. The proposed network architecture can realize high information S/N ratio by constructing multiple groups for different communication purposes, and can also realize security by logically separating those groups. An existing user terminal cannot be associated with multiple groups. Hence, in our network architecture, multiple groups are terminated at a gateway called SA (Security Agent), which realizes multiple association to several groups. A user terminal is directly connected to a Web concentrator running on SA. Similarly to a portal Web site, a Web concentrator aggregates contents from multiple groups, and transmits the aggregated contents to a user terminal. Several networking technologies for realizing group-based communications have been proposed. From the comparative evaluation of those networking technologies, we show that (1) SSL-VPN is suitable for access networks connecting a user terminal and SA, and that (2) MPLS-VPN is suitable for the backbone network connecting SAs. We also show that the proposed network architecture realizes security and high information S/N ratio for Web-based applications.

In recent years, several social activities have been shifting into networked virtual society, called Cybersociety, because of the rapid advancement of network technologies. For designing and realizing a new service in Cybersociety, it is crucial to fully investigate the desired structure of commercial transactions and circulation activities in the Cybersociety. For this purpose, it must be fruitful to investigate the structure of business relationships among existing corporations in real society, which are believed to be working effectively. In this paper, by utilizing a corporate information database, we first build a corporate transaction network based on the dealings information among Japanese corporations. We then investigate the structure of the corporate transaction network by applying several network analysis techniques, which have been used for analyzing various social networks. We show that the average distance of the corporate transaction network is approximately 3.4-5.4, and that it has a scale-free property with a power-law index of 2.1. We also show that our proposed structural superiority index of the corporate transaction network is greatly related to several stock price indices and profit financial indices