Robust stability of large-scale systems which contain time-invariant lur'e-type uncertainties in subsystems and norm-bounded uncertainties in interconnections

In this paper a new frequency-domain condition for the robust stability of a class of large-scale systems is derived. It is assumed that each subsystem contains one time-invariant nonlinearity satisfying a sector condition, and that the interconnecting functions are linearly bounded by the norms of the scalar outputs of subsystems. In deriving the above such Lur'e-type Lyapunov functions of subsystems are constructed so that their weighted sum is a Lyapunov function of the overall system. This condition is potential to give a sharper result than the circle-condition-type result which was obtained previously. Furthermore, a method to estimate the domain of attraction using the above Lyapunov function is also given when the sector condition is satisfied only locally.     

Membrane localization, topology, and mutual stabilization of the rnfABC gene products in Rhodobacter capsulatus and implications for a new family of energy-coupling NADH oxidoreductases

The rnf genes in Rhodobacter capsulatus are unique nitrogen fixation genes that encode potential membrane proteins (RnfA, RnfD, and RnfE) and potential iron-sulfur proteins (RnfB and RnfC). In this study, we first analyzed the localization and topology of the RnfA, RnfB, and RnfC proteins. By activity and immunoblot analysis of expression of translational fusions to Escherichia coli alkaline phosphatase, RnfA protein was shown to span the chromatophore membrane with its odd-numbered hydrophilic regions exposed to periplasm. By alkaline treatment of membrane fractions and following immunoblot analysis using antibodies against recombinant proteins expressed in E. coli, both RnfB and RnfC proteins were revealed to situate at the periphery of the chromatophore membranes. Second, mutual interaction of the Rnf proteins was analyzed by immunochemical determinations of RnfB and RnfC proteins in rnf mutants and their complemented derivatives. The contents in cellular fractions indicated that RnfB and RnfC stabilize each other and that the presence of RnfA is necessary for stable existence of both proteins. These results support a hypothesis that the Rnf products are subunits of a membrane complex. Finally, we detected homologs of rnf genes in Haemophilus influenzae and Vibrio alginolyticus by data base searches and in E. coli by cloning of a fragment of an rnfA homolog followed by a data base search. Close comparisons revealed that RnfC has potential binding sites for NADH and FMN which are similar to those found in proton-translocating NADH:quinone oxidoreductases and that RnfA, RnfD, and RnfE show similarity to subunits of sodium-translocating NADH:quinone oxidoreductases. We predict that the putative Rnf complex represents a novel family of energy-coupling NADH oxidoreductases.     

Molecular cloning of a novel putative G protein-coupled receptor (GPCR21) which is expressed predominantly in mouse central nervous system

Agarose gel affinity electrophoresis has been used to demonstrate interactions between autologous IgG and specific erythrocyte membrane proteins. These binding phenomena are here further examined by combining affinity electrophoresis with affinity chromatography, absorption experiments, and immunoblotting. It is demonstrated that the interactions are highly dependent on polyreactive IgG binding favored by the low ionic strength conditions of the electrophoretic assay. Thus, about 25% of normal IgG under low ionic strength conditions bound to the purified cytoskeletal protein, spectrin, immobilized on Sepharose. This IgG reacted in affinity electrophoresis in a polyspecific fashion with the same array of membrane proteins as before the low ionic strength-affinity chromatography. Further, the binding seen in affinity electrophoresis, including the interaction with spectrin, was completely abolished by preabsorption of the IgG with spectrin-devoid membranes. The charge characteristics of an IgG subclass might be responsible for the observed binding. However, the observed precipitate formation suggested an interaction involving at least two binding sites on each molecule and the binding appears to require structurally intact IgG because reductive treatment with dithiothreitol diminished the reactivity considerably. Conclusively, under the conditions of affinity electrophoresis with ligand present in the gel, electrostatic interactions are amplified. The degree of binding of IgG to erythrocyte membrane proteins that take place under these conditions does not reflect binding which would occur to the same extent under physiological ionic strength conditions.     

Survey of the sensitivities of clinical isolates to antibacterial agents (annual report)

Research groups were formed in 21 institutions nationwide to investigate carbapenem resistance. The activities of various antibacterial agents, principally carbapenems were tested against clinical isolates collected from these institutions. The broth microdilution method was used to determine the minimum inhibitory concentrations (MIC) of 17 antibacterial agents for 1,282 strains of 11 bacterial species isolated at all institutions between October and December 1995. The results were as follows: 1. Carbapenems exhibited strong antibacterial activities against MSSA and Streptococcus pneumoniae. Their activities against Enterococcus faecalis were comparable to that of ABPC. Carbapenems showed low activities against MRSA. 2. OFLX exhibited the greatest antibacterial activity against Haemophilus influenzae, followed by MEPM. The antibacterial activities of the other carbapenems were comparable to those of FMOX and CTM. 3. The carbapenems showed high activities against Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Bacteroides fragilis group. Their activities were greater than that exhibited by other beta-lactam antibacterial agents. The carbapenems also exhibited greater antibacterial activities against Serratia marcescens than the other beta-lactam antibacterial agents, but some resistant strains were detected. 4. The antibacterial activities of carbapenems against Pseudomonas aeruginosa were comparable to those of CAZ, AZT, AMK.     

Electroviscous effect in dilute suspensions of ionic polymer latices

The viscosity of dilute suspensions of ionic polymer latices was measured using a variable-shear capillary viscometer, a rotational viscometer and an Ubbelohde viscometer. The viscosity of the suspension was much larger than the Einstein theoretical value and showed a marked shear-thinning behaviour, due to the electroviscous effect. The dependence of the reduced viscosity of latex suspensions on latex concentration, salt concentration and solvent was essentially the same as that of linear ionic polymer solutions. Counterion effect was also investigated.     

Local stability of composite systems--Frequency-domain condition and estimate of the domain of attraction

This paper is concerned with such composite systems whose subsystems contain one nonlinearity each and whose interconnections are functions of the scalar outputs of subsystems. A frequency-domain condition which assures local asymptotic stability is given under the assumptions that each nonlinearity satisfies a sector condition, that interconnections are linearly bounded, and that linear parts of subsystems may have unstable poles. In deriving the above result, such Lyapunov functions of subsystems are constructed so that their weighted sum is a Lyapunov function of the overall system. A method to estimate the domain Of attraction based on the above Lyapunov functions is also studied. When the bounds on nonlinearities hold true in the entire space and when the linear parts do not have unstable poles, the present condition turns out to be the same with the L2-stability condition which was obtained before by Araki.     

A soft-solution process for recovering rare metals from metal/alloy-wastes by grinding and washing with water

We have developed a novel process for recovering metals from alloy-wastes by using a mechanochemical (MC) reaction. The process consists of co-grinding both alloy and polyvinyl chloride (PVC) samples, followed by washing with water and filtration. The co-grinding of the wastes causes a solid-state MC reaction to form metal chlorides and hydrocarbon in the product. The former products are soluble in water, so they can be recovered from the wastes by washing with water, followed by filtration. The PVC waste plays a significant role as a chlorine source in the MC reaction. After filtration, the solid residue can be used as a fuel, due to the absence of chlorine in the product, and the filtrate is subjected to hydrometallurgical process to extract metals from the solution.     

Characterization of Fish Myofibrillar Protein by Conjugation with Alginate Oligosaccharide Prepared Using Genetic Recombinant Alginate Lyase

ABSTRACT: The production of alginate lyase using genetically modified Escherichia coli was superior to the purification of alginate lyase from a culture medium of Pseudoalteromonas elyakovii regarding production efficiency. When alginate oligosaccharide (AO) prepared using genetic recombinant alginate lyase was introduced to fish myofibrillar proteins, the protein obtained high water solubility and improved thermal stability, similarly to AO prepared using wild-type lyase. Therefore, the use of genetic recombinant technology for the production of alginate lyase would be useful for the functional improvement of fish myofibrillar proteins by conjugation with AO.