Data preprocessing and output evaluation of an autoassociative neural network model for online fault detection in virginiamycin production

In this study, an artificial autoassociative neural network (AANN) was used online to detect deviations from normal antibiotic production fermentation using conventional process variables. To improve the efficiency of extracting hidden information contained in multidimensional process variables, and to finally render the AANN adequate for fault detection, we explored the following methods: selection of process variables; preprocessing of data that involved normalizing the training data of the AANN; and evaluation of data that involved assessing the output of the AANN. A method for fault detection in virginiamycin M and S production by Streptomyces virginiae was successfully developed based on these techniques.     

Kinetic studies on hot-stretching of polyacrylonitrile-based carbon fibres by using internal resistance heating Part II Changes in structure and mechanical properties

The effects of the stretching stress applied during high-temperature heat treatment of polyacrylonitrile-based carbon fibres on the development of the structure and the mechanical properties of the resulting carbon fibres, were investigated kinetically by using internal resistance heating. The tensile modulus of the carbon fibres increased with a faster rate under a larger stretching stress. The tensile strength decreased initially as the carbonization progressed, but increased appreciably under a larger stretching stress, a trend which was not observed under a smaller stretching stress. The temperature–time superposition was applicable with respect to the development of the crystallite and the microvoid structures and the changes in the resistivity, density and apparently the tensile strength, by using a common shift factor. The changes in the longitudinal strain, however, showed a different temperature dependence from that of the structural development.     

Mechanical properties of tussah silk fibers treated with methacrylamide

Tussah silk fibers were treated with methacrylamide (MAA). The polymerization of MAA onto tussah silk fibers and the mechanical properties of the MAA-treated tussah silk fibers were investigated. The tanning agent contained in tussah silk fibers acted as an inhibitor to the radical polymerization of MAA. The alkali treatment enhanced the swelling of noncrystalline regions of the tussah silk fibers and promoted the polymerization of MAA onto the tussah silk fibers. The cross-sectional area of the MAA-treated tussah silk fiber was given by the sum of the cross-sectional area of the original silk fiber and that of the MAA polymer. Breaking load of the fibers was almost unchanged by the MAA treatment, while rigidity was markedly increased. Young's modulus of the MAA-treated tussah silk fibers decreased with decreasing volume fractions of the fiber in the MAA-treated tussah silk fibers. Young's modulus of the MAA polymer in the MAA-treated tussah silk fibers was estimated by extrapolating the relation between Young's moduli and the volume fractions of the fiber to zero volume fraction. Young's modulus of the MAA polymer in the MAA-treated tussah silk fibers was significantly larger than the modulus of a MAA polymer plate. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2051–2057, 1997     

Small-angle X-ray scattering of long-period structures forming bundles

Small-angle X-ray scattering (SAXS) patterns have been calculated based on a structure model, which consisted of the bundles of long-period structures. The proposed model has produced various scattering patterns of polymers, such as the equatorial, layer line, four-spot, droplet-shaped and triangular scattering. The 0.5th order scattering has arisen when the disorder in or between the long-period structures was large even though the structure did not have the periodicity directly related to the scattering maximum. A slight decrease in the disorder due to slip between the long-period structures has accounted for the sudden change of the SAXS pattern of a poly(ethylene terephthalate) fiber from the four-spot to the layer line scattering which was caused by a slight tensile deformation.     

Supramolecular morphology of two-step melt-spun poly(dioxanone) fibers

Structure of poly(dioxanone) (PPDX) fibers produced through a two-step melt-spinning process with an additional short-period annealing above the melting temperature of PPDX was investigated and the effect of annealing on the degradation behavior was discussed. The morphological study carried out by etching the fibers using a phosphate or permanganate solution suggested that the fibers take a skin–core structure, and both the skin layer and the core region consist of a bundle of microfibrils. The micro-beam X-ray diffraction analysis revealed that the short-period annealing in the production process only slightly promotes the crystallization in the skin layer but contributes to increasing the packing of amorphous chains near the skin, which seems to be the controlling factor of the hydrolytic degradation behavior of the fibers.     

Potassium-doped Co3O4 catalyst for direct decomposition of N2O

Direct decomposition of nitrous oxide (N₂O) on K-doped Co₃O₄ catalysts was examined. The K-doped Co₃O₄ catalyst showed a high activity even in the presence of water. In the durability test of the K-doped Co₃O₄ catalyst, the activity was maintained at least for 12 h. It was found that the activity of the K-doped Co₃O₄ catalyst strongly depended on the amount of K in the catalyst. In order to reveal the role of the K component on the catalytic activity, the catalyst was characterized by XRD, XPS, TPR and TPD. The results suggested that regeneration of the Co²⁺ species from the Co³⁺ species formed by oxidation of Co²⁺ with the oxygen atoms formed by N₂O decomposition was promoted by the addition of K to the Co₃O₄ catalyst.     

Viscoelastic and thermal decomposition behaviors of polytetrahydrofuran binder prepared using glycerin as a crosslinking modifier

Polytetrahydrofuran (PTHF) is an effective binder ingredient used for improving the performance of propellants. PTHF becomes sufficiently rubbery for use as a binder with the addition of an adequate crosslinking modifier. This study investigated the viscoelastic and thermal decomposition behaviors of the PTHF binder prepared using glycerin as a crosslinking modifier, as well as the influence of the molecular weight of PTHF on the characteristics of the PTHF binder. The curing behavior of the PTHF binder was suitable for the manufacture of propellants, and the superior tensile properties of the PTHF binder made it suitable for use as a propellant binder. The degree of crosslinking of the samples decreased as the molecular weight of the PTHF increased. The PTHF binder has unique dynamic mechanical properties owing to its melting and chemical structure, and these properties were dependent on the molecular weight of PTHF. The glass transition temperature (T_g) and the loss tangent at T_g decreased as the molecular weight of the PTHF increased. The temperature and frequency dependence of the PTHF binder were influenced by the melting point of PTHF. The viscoelastic properties of the binder prepared using PTHF with a molecular weight of 650 followed the time–temperature superposition principle. The activation energy for the relaxation of this binder varied remarkably at the melting point of PTHF. The thermal decomposition behavior indicated that at low temperatures, the consumption rate of the binder with low‐molecular‐weight PTHF was slightly larger than that of the binder with high‐molecular‐weight PTHF. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Kinetic studies on hot-stretching of polyacrylonitrile-based carbon fibers by using internal resistance heating Part 1 Changes in resistivity and strain

The effects of the stretching stress applied during high temperature heat-treatment of polyacrylonitrile(PAN)-based carbon fibers on the structural development and the properties of the fibers were investigated kinetically using internal resistance heating. The temperature-time superposition could be applied to the changes in structural parameters, resistivity and tensile strength during heat-treatment using the same shift factors. The application of the stretching stress effectively reduced the fractions of slower rate processes and the activation energy of the structural development in the temperature region below about 1800°C, and also influenced on the structural features. The longitudinal strain induced during heat-treatment increased in proportion to the logarithmic treatment time, showing different kinetics from that of the structural development.     

Effect of sulfur sources on specific desulfurization activity of Rhodococcus erythropolis KA2-5-1 in exponential fed-batch culture

The effects of sulfur sources on the desulfurization activity of Rhodococcus erythropolis KA2-5-1 were investigated by using an exponential fed-batch culture technique. The feed rate of a sulfur source was controlled independently of the feed rate of ethanol, which was used as a carbon and energy source. Among the sulfur sources examined were dibenzothiophene (DBT), ammonium sulfate, L-cysteine, L-methionine, and 2-amino-ethanesulfonic acid. When the fed-medium contained DBT as the sole sulfur source, KA2-5-1 cells showed a maximum desulfurization activity of approximately 130 mmol 2-HBP kg-cell(-1) h(-1). Similar levels of enzyme activity were also achieved with inexpensive ammonium sulfate by using the exponential fed-batch culture technique. In addition, higher levels of desulfurization activity were achieved by increasing the dosage of the DBT desulfurization (dsz) operon and dszD gene in R. erythropolis KA2-5-1. The recombinant strain showed a maximum desulfurization activity of approximately 250 mmol 2-HBP kg-cell(-1) h(-1) in the exponential fed-batch cultures.     

Microaeration enhances productivity of bioethanol from hydrolysate of waste house wood using ethanologenic Escherichia coli KO11

This is the first study showing the successful application of waste house wood (WHW) to the pilot-scale production of bioethanol by hydrolysis using diluted acid and fermentation using the ethanologenic recombinant Escherichia coli KO11. The major sugars in the WHW hydrolysate were glucose, mannose and xylose; the percentages were approximately 35%, 35% and 20% (w/w), respectively. In anaerobic fermentation using a 5-l reactor in which the oxygen transfer rate (OTR) was 0 mmol/(l x h), KO11 consumed only 25% of the xylose in the WHW hydrolysate over the examined fermentation time of 100 h; however, hexoses such as glucose and mannose were consumed completely. Microaeration at an OTR of 4 mmol/(l x h) enhanced the xylose utilization ratio of KO11 to 100%, at which the ethanol concentration was 35.4 g/l and the ethanol yield was 0.42, although the maximum ethanol concentrations were 28.8 and 26.6 g/l at OTRs of 0 mmol/(l x h) and 15 mmol/(l x h), respectively. Moreover, this microaerobic fermentation at OTR of 4 mmol/(l x h) was applied to 1000-l scale bioethanol production using the WHW hydrolysate. The xylose utilization ratio reached 100% and the ethanol yield was determined to be 0.45 for a 63-h fermentation, which were comparable to those obtained from the laboratory-scale fermentation.