Development of high-rate anaerobic ammonium-oxidizing (anammox) biofilm reactors

To promptly establish anaerobic ammonium oxidation (anammox) reactors, appropriate seeding sludge with high abundance and activity of anammox bacteria was selected by quantifying 16S rRNA gene copy numbers of anammox bacteria by real-time quantitative PCR (RTQ-PCR) and batch culture experiments. The selected sludge was then inoculated into up-flow fixed-bed biofilm column reactors with nonwoven fabric sheets as biomass carrier and the reactor performances were monitored over 1 year. The anammox reaction was observed within 50 days and a total nitrogen removal rate of 26.0 kg-Nm(-3)day(-1) was obtained after 247 days. To our knowledge, such a high rate has never been reported before. Hydraulic retention time (HRT) and influent NH(4)(+) to NO(2)(-) molar ratio could be important determinant factors for efficient nitrogen removal in this study. The higher nitrogen removal rate was obtained at the shorter HRT and higher influent NH(4)(+)/NO(2)(-) molar ratio. After anammox reactors were fully developed, the community structure, spatial organization and in situ activity of the anammox biofilms were analyzed by the combined use of a full-cycle of 16S rRNA approach and microelectrodes. In situ hybridization results revealed that the probe Amx820-hybridized anaerobic anammox bacteria were distributed throughout the biofilm (accounting for more than 70% of total bacteria). They were associated with Nitrosomonas-like aerobic ammonia-oxidizing bacteria (AAOB) in the surface biofilm. The anammox bacteria present in this study were distantly related to the Candidatus Brocadia anammoxidans with the sequence similarity of 95%. Microelectrode measurements showed that a high in situ anammox activity (i.e., simultaneous consumption of NH(4)(+) and NO(2)(-)) of 4.45 g-N of (NH(4)(+)+NO(2)(-))m(-2)day(-1) was detected in the upper 800 microm of the biofilm, which was consistent with the spatial distribution of anammox bacteria.     

Construction of a dictionary of sequence motifs that characterize groups of related proteins

An automatic procedure is proposed to identify, from the proteinsequence database, conserved amino acid patterns (or sequencemotifs) that are exclusive to a group of functionally relatedproteins. This procedure is applied to the PIR database anda dictionary of sequence motifs that relate to specific superfamiliesconstructed. The motifs have a practical relevance in identifyingthe membership of specific superfamilies without the need toperform sequence database searches in 20% of newly determinedsequences. The sequence motifs identified represent functionallyimportant sites on protein molecules. When multiple blocks existin a single motif they are often close together in the 3-D structure.Furthermore, occasionally these motif blocks were found to besplit by introns when the correlation with exon structures wasexamined.     

Functional modification of biodegradable polyesters through a chemoselective approach: application to biomaterial surfaces

This paper presents an overview of functional modifications of synthetic aliphatic polyesters and a new synthetic route to graft functional moieties onto the polyester backbone by a chemoselective approach. Aminooxy groups react efficiently and selectively with ketones or aldehydes to form oxime linkages under mild reaction conditions without catalysts, even in the presence of other functional groups. Chemoselective coupling of aminooxy‐terminated poly(ethylene oxide) (PEO) onto ketone‐bearing poly(ε‐caprolactone) (PCL) was exploited to prepare comb‐shaped copolymers that exhibit cell resistance when the PEO content is above 30 wt%. The free hydroxyl groups of PEO chain ends allowed further incorporation of cell signaling peptides including the sequence RGD. The results show chemoselective coupling to be a promising general route for introducing functional pendant groups onto most polyesters obtained by ring‐opening polymerization without backbone degradation. Copyright © 2006 Society of Chemical Industry     

Unstable cracking of medium density polyethylene

The ductile instability characterization of medium density polyethylene (MDPE) has been studied with theJ integralR curve method. The loading of variously notched samples in three-point bending using a compliant test fixture showed that sudden unstable cracking occurred after the commencement of stable ductile cracking. The tearing modulus which is obtained from theR curve can describe the transition from stable to unstable crack. Instability occurs when an applied situation depending on loading system and/or sample geometry exceeds the tearing modulus of MDPE.     

Creep properties of Sn-8Mass%Zn-3Mass%Bi lead-free alloy

The creep properties of Sn-8mass%Zn-3mass%Bi were investigated and compared with those of other lead-free solders and a Sn-Pb eutectic solder. The creep rupture time decreases with increasing the initial stress and the temperature. For high stresses, the linear relationships between the minimum strain rate and the applied stress were observed. The stress exponents were examined to be 9.3, 7, and 4 at 298 K, 348 K, and 398 K, respectively. For low stresses, the minimum creep rate becomes relatively fast, and the creep resistance diminishes. In this range, secondary creep reduces, and the tertiary creep predominates. The creep properties of Sn-8Zn-3Bi are similar to those of Sn-Ag alloys at high stresses and those of Sn-0.5Cu at low stresses.     

Development of Bi-base high-temperature Pb-free solders with second-phase dispersion: Thermodynamic calculation, microstructure, and interfacial reaction

Bismuth and its alloys are candidates for Pb-free high-temperature solders that can be substituted for conventional Pb-rich Pb−Sn solders (melting point (mp) = 573 – 583 K). However, inferior properties such as brittleness and weak bonding strength should be improved for practical use. To that end, BiCu−X (X=Sb, Sn, and Zn) Pb-free high-temperature solders are proposed. Miscibility gaps in liquid BiCu−X alloys were surveyed using the thermodynamic database ADAMIS (alloy database for micro-solders), and compositions of the BiCu−X solders were designed on the basis of calculation. In-situ composite solders that consist of a Bi-base matrix with fine intermetallic compound (IMC) particles were produced by gas-atomizing and melt-spinning methods. The interfacial reaction between in-situ composite solders and Cu or Ni substrates was investigated. The IMCs at the interface formed a thin, uniform layer, which is an appropriate morphology for a reliable solder joint.     

A multimodal neural network with single-state predictions for protein secondary structure

Prediction of protein secondary structure is considered to be an important step toward elucidating the three-dimensional structure and function of proteins. We have developed a multimodal neural network (MNN) to predict protein secondary structure. The MNN is composed of several subclassifiers for single-state predictions using neural networks and a decision neural network (DNN). Each subclassifier employs a number of subnetworks to predict the single-state of the secondary structure individually and produces the final results by majority decision. The DNN uses a three-layer neural network to produce the final overall prediction from the outputs of the single-state predictions. The MNN gives an overall accuracy of 71.1% with corresponding Matthews correlation coefficients of C_H = 0.62 and C_E = 0.53. The prediction test is based on a database of 126 nonhomologous protein sequences. This work was presented, in part, at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24#x2013;26, 2003.     

Phase equilibria in the Cu-Fe-Mo and Cu-Fe-Nb systems

Phase equilibria in the Cu-Fe portion of the Cu-Fe-Mo and the Cu-Fe-Nb systems, in the temperature ranges 1073 to 1573 K and 1373 to 1573 K, respectively, were determined by metallography and scanning electron microscopy-energy dispersive x-ray methods. Based on the present experimental data combined with the previous assessments of the component binary systems, thermodynamic calculations of phase equilibria were carried out adopting the subregular solution model to describe the Gibbs energies of the liquid, bcc, and fcc phases. The evaluated thermodynamic parameters lead to a better fit between calculations and experimental data in both the Cu-Fe-Mo and Cu-Fe-Nb systems.