Effect of pitting corrosion on strength of web plates subjected to patch loading

Pitting corrosion is typical corrosion observed on coated hold frames in way of cargo holds of bulk carriers, which exclusively carry coal and iron ore. Extensive survey on the effect of pitting corrosion on structural strength under a wide variety of loading conditions is necessary to clarify the relationship between pitting intensity and residual strength in detail. In the present study, a series of tests has been conducted on structural models which consist of web, shell and face plates to investigate the effect of pitting corrosion on strength of web plates subjected to patch loading. In these tests, artificial pitting was made on the web plates and two equal concentrated loads have been applied vertically at the one third points of simply supported models. It was found that web crippling behavior is strongly affected by the pit distribution on the web plates. According to the FE-analyses following the experiment, ultimate strength of the web plates with pitting under patch loading is a little smaller than or almost the same as that of the web plates with uniform corrosion in terms of average thickness loss.     

Organics removal of combined wastewater through shallow soil infiltration treatment: a field and laboratory study

Soil infiltration treatment (SIT) was proved to be an effective and low-cost treatment technique for decentralized effluents in the areas without perfect sewage systems. Field-scale experiments were conducted under several conditions to assess organics removals through a shallow soil infiltration treatment (SSIT, with effective depth 0.3m) of combined wastewater (discharge from toilets, restaurants and a gas station), while bench-scale soil column experiments were performed in laboratory in parallel to investigate biological and abiological effects of this kind of system. From the start-up to the 10th month, the field SSIT trenches experienced the lowest and highest temperatures of the operation period in Shanghai and exhibited effective organics removals after maturation, with the highest removal rate 75.8% of chemical oxygen demand (COD), highest ultraviolet absorption at 254 nm (UV(254)) decrease by 67.2% and 35.2-100% removals of phenolic and phthalate pollutants. The laboratory results indicated that more organics could be removed in room-temperatured (25+/-2 degrees C) SSIT systems under different influent COD concentrations from 45 mg/l to 406 mg/l, and the highest total COD removal rate could reach 94.0%, in which biological effect accounted for 57.7-71.9%. The results showed that temperature and hydraulic loading rate were the most important factors influencing the removals of COD and organic pollutants in SSIT.     

Characterization of neurons differentiated from mouse embryonic stem cells using conditioned medium of dorsal root ganglia

Mouse embryonic stem (ES) cells have the pluripotent ability to differentiate in vitro into various cell lineages, including neurons. Adding chick dorsal root ganglion (DRG) conditioned medium (CM) to the culture medium promotes the differentiation of ES cells into neurons. We determined the types of neurons that differentiate from ES cells. The addition of DRG-CM caused nearly half of all ES cells on the periphery of the colony sphere to differentiate into neurons. Immunofluorescence analysis showed that the neurons that differentiated from ES cells were mainly motor, GABAergic, serotonergic, and cholinergic neurons. Of particular note, flow cytometry showed that approximately 50% of betaIII-tubulin-positive neurons were motor neurons. This indicates that DRG-CM induces ES cells to differentiate into motor neurons as target of DRG neurons (sensory neurons).     

Morphological study on three kinds of two-dimensional spherulites of poly(butylene terephthalate) (PBT)

Three kinds of thin film specimens, each of which containing one of the three types of two-dimensional poly(butylene terephthalate) (PBT) spherulites (i: usual-positive type, ii: usual-negative type, and iii: unusual type), were prepared and studied mainly by transmission electron microscopy. It was confirmed that all these kinds of spherulites are made up of only the α-modification crystals, and the growth directions for usual-positive type, usual-negative type, and unusual type are the [010]^∗, ^∗, and ^∗ directions in the reciprocal lattice, respectively. Furthermore, the arrangement of unit cell in each type of the spherulites was determined. The relationships between the arrangements of unit cell and the types of each resulting spherulite are discussed.     

Assembling nanowires from Mo-S clusters and effects of iodine doping on electronic structure

Using ab initio calculations, we find high stability of octahedral Mo6S8 clusters, which can further be condensed to form Mo3nS3n+2 (n, an integer) nanowires. These linear structures are energetically more favorable compared with other closed-packed polyhedral isomers of Mo-S clusters. The octahedral units in nanowires are stabilized by strong Mo-Mo interactions and p-d hybridization between Mo 4d and S 2p orbitals. There is a free electron-like band that crosses the Fermi energy in infinite nanowires and leads to their metallic character. Iodine doping acts as electron donor and can be used to tailor the electronic conductivity. For Mo12S8I4 nanowires, both electrons and holes are found to contribute to conduction. These nanowires are energetically more favorable than the experimentally obtained Mo12S6I12 nanowires.     

Molecular modeling of single polypeptide chain of calcium-binding protein p26olf from dimeric S100B()

P26olf from olfactory tissue of frog, which may be involvedin olfactory transduction or adaptation, is a Ca²⁺-binding proteinwith 217 amino acids. The p26olf molecule contains two homologousparts consisting of the N-terminal half with amino acids 1–109and the C-terminal half with amino acids 110–217. Eachhalf resembles S100 protein with about 100 amino acids and containstwo helix–loop–helix Ca²⁺-binding structural motifsknown as EF-hands: a normal EF-hand at the C-terminus and apseudo EF-hand at the N-terminus. Multiple alignment of thetwo S100-like domains of p26olf with 18 S100 proteins indicatedthat the C-terminal putative EF-hand of each domain containsa four-residue insertion when compared with the typical EF-handmotifs in the S100 protein, while the N-terminal EF-hand ishomologous to its pseudo EF-hand. We constructed a three-dimensionalmodel of the p26olf molecule based on results of the multiplealignment and NMR structures of dimeric S100B(ßß)in the Ca²⁺-free state. The predicted structure of the p26olfsingle polypeptide chain satisfactorily adopts a folding patternremarkably similar to dimeric S100B(ßß). Each domainof p26olf consists of a unicornate-type four-helix bundle andthey interact with each other in an antiparallel manner formingan X-type four-helix bundle between the two domains. The twoS100-like domains of p26olf are linked by a loop with no sterichindrance, suggesting that this loop might play an importantrole in the function of p26olf. The circular dichroism spectraldata support the predicted structure of p26olf and indicatethat Ca²⁺-dependent conformational changes occur. Since theC-terminal putative EF-hand of each domain fully keeps the helix–loop–helixmotif having a longer Ca²⁺-binding loop, regardless of the four-residueinsertion, we propose that it is a new, novel EF-hand, althoughit is unclear whether this EF-hand binds Ca²⁺. P26olf is a newmember of the S100 protein family.     

Curing of epoxy resin by ultrafine silica modified by grafting of hyperbranched polyamidoamine using dendrimer synthesis methodology

Hyperbranched polyamidoamine–grafted silica was prepared according to dendrimer synthesis methodology. The modified silica was dispersed uniformly in epoxy resin, and the curing of epoxy resin proceeded successfully by heating in the presence of the modified silica; the gel fraction of the epoxy resin cured by the hyperbranched polyamidoamine–grafted silica (grafting = 80.2%) reached 77% at 170°C after 48 h. The gel fraction increased with increasing terminal amino group content of the hyperbranched polyamidoamine–grafted silica. In addition, the curing ability of the silica increased by complexation of the terminal amino groups of the grafted polyamidoamine with boron trifluoride. The modulus of elasticity of the curing materials obtained using the modified silica as a curing agent was lower than that using conventional a curing agent such as ethylenediamine in the presence of untreated silica. On the other hand, the heat resistance of the curing product using the modified silica was superior to that using ethylenediamine, but no difference in glass‐transition temperature was observed. It is expected that hyperbranched polyamidoamine grafted‐silica is incorporated uniformly with chemical bonds in the matrix of the epoxy resin. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 573–579, 2001     

An associative memory model derived from cross-coupled Hopfield nets and its role in noise-space dynamics

In this paper, the association characteristics of cross-coupled Hopfield nets (CCHN) proposed as a modular neural network model are discussed analytically. In a CCHN, an arbitrary number of modules (Hopfield networks) can be mutually connected via feedforward networks called internetworks, whose output generates interactions among module networks. To evaluate the CCHN as a modular neural network, it has previously been applied to associative memory. Although its excellent association performance is supported by many simulation results, it is still difficult to compute the memory capacity exactly or to examine the dynamic properties rigorously, because CCHN information processing includes strong nonlinearity. Hence, as the first step to an analytical approach, this paper focuses on a single-module CCHN whose interaction is realized by a two-layered feedforward internetwork. In this case, the connection matrix of the CCHN degenerates into a single square-matrix, as does a conventional auto-association type of associative memory. Using eigenvalue analysis for the connection matrix, we reveal that the essential differences between the association characteristics of a CCHN and a conventional autocorrelation associative memory originate from dynamics in the noise-space that is the orthogonal complement of the subspace generated from memory patterns. ©1998 Scripta Technica, Electr Eng Jpn, 125(2): 27–34, 1998     

Characterization of a Novel Thermostable Dye-Linked l-Lactate Dehydrogenase Complex and Its Application in Electrochemical Detection

Flavoenzyme dye-linked l-lactate dehydrogenase (Dye-LDH) is primarily involved in energy generation through electron transfer and exhibits potential utility in electrochemical devices. In this study, a gene encoding a Dye-LDH homolog was identified in a hyperthermophilic archaeon, Sulfurisphaera tokodaii. This gene was part of an operon that consisted of four genes that were tandemly arranged in the Sf. tokodaii genome in the following order: stk_16540, stk_16550 (dye-ldh homolog), stk_16560, and stk_16570. This gene cluster was expressed in an archaeal host, Sulfolobus acidocaldarius, and the produced enzyme was purified to homogeneity and characterized. The purified recombinant enzyme exhibited Dye-LDH activity and consisted of two different subunits (products of stk_16540 (α) and stk_16550 (β)), forming a heterohexameric structure (α3β3) with a molecular mass of approximately 253 kDa. Dye-LDH also exhibited excellent stability, retaining full activity upon incubation at 70 °C for 10 min and up to 80% activity after 30 min at 50 °C and pH 6.5–8.0. A quasi-direct electron transfer (DET)-type Dye-LDH was successfully developed by modification of the recombinant enzyme with an artificial redox mediator, phenazine ethosulfate, through amine groups on the enzyme’s surface. This study is the first report describing the development of a quasi-DET-type enzyme by using thermostable Dye-LDH.     

Surface grafting of polymers onto glass plate: Polymerization of vinyl monomers initiated by initiating groups introduced onto the surface

The surface grafting of polymers onto a glass plate surface was achieved by the polymerization of vinyl monomers initiated by initiating groups introduced onto the surface. Azo groups were introduced onto the glass plate surface by the reaction of 4,4′-azobis(4-cyanopentanoic acid) with isocyanate groups, which were introduced by the treatment with tolylene-2,4-diisocyanate. The radical polymerization of various vinyl monomers was initiated by azo groups introduced onto the glass plate surface and the corresponding polymers were grafted from the surface: The surface grafting of polymers was confirmed by IR spectra, and the contact angle of surface, with water. The contact angle of the glass plate increased by the grafting of hydrophobic polymers, but decreased by the grafting of hydrophilic polymers. The radical postpolymerization was successfully initiated by the pendant peroxycarbonate groups of grafted polymer on the surface to give branched polymer-grafted glass plate. The cationic polymerization of vinyl monomers was also successfully initiated by benzylium perchlorate groups introduced onto the glass plate surface and the corresponding polymers were grafted onto the surface. The contact angle of the glass plate surface obtained from the cationic polymerization of styrene was larger than that obtained from the radical polymerization. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2165–2172, 1997