THE DEGRADATION OF CHlTOSAN WITH THE AID OF LIPASE FROM RHIZOPUS JAPONICUS FOR THE PRODUCTION OF SOLUBLE CHlTOSAN

Lipase from Rhizopus japonicus degraded chitosan resulting in soluble chitosan hydrolysates with molecular weight of about 30–50 kDa as shown by size exclusion chromatography. Optimal temperature for the hydrolysis of chitosan was 40C. The chitosan degradation products were fractionated stepwise according to their molecular weights by ultrafiltration with the filtration range of over 0.1 μm, 0. l μm to 30 kDa, 30 kDa to 10 kDa, 10 to 3 kDa, and 3 to 0.2 kDa. These fractions exhibited molecular weights of 50, 41, 41, 35, and 30 kDa, respectively. The molecular weights did not coincide with the pore size of filter membranes. Chitosan hydrolysate exhibited almost the same structural composition in IR spectra as chitosan flakes, except the peak of 1550 nm^?1 that appeared to be the COO residue shifted from sodium acetate buffer to amine residue of chitosan. All fractions showed high solubility at neutral pH. The chitosan hydrolysates exhibiting molecular weights between 30 and 41 kDa were considered to be most suitable as a food additive or functional agent as demonstrated by sensory evaluation.     

The defensive use of IT in a newly vulnerable market: The New York Stock Exchange, 1980–2007

New technologies enable entrants to create business models that threaten incumbents in a range of industries. This paper extends the framework of newly vulnerable markets to explore the dynamics of competition between entrants and an incumbent through a study of the New York Stock Exchange. For over 200 years, the NYSE has operated a physical market for trading securities. Beginning in the 1960s, it employed information technology to process increasing trading volumes and to disseminate data on stock prices and volumes. The Exchange invested heavily in IT for its trading floor, and defended it against electronic markets enabled by new technologies. In 2005 various pressures forced the NYSE into a merger with Archipelago, a leading electronic exchange. The NYSE’s latest market system, Hybrid, launched in 2006, is the first at the NYSE that enables investors to bypass the trading floor completely. Despite the new technology, its share of trading volumes fell. This paper documents four eras of IT management at the exchange, presenting a detailed 27-year history. The evidence shows that while IT investments helped the Exchange defend floor trading and its market share for a number of years, it finally had to adopt the technology of all-electronic exchanges.     

Hydrogen-enhanced cracking of 2205 duplex stainless steel

Tensile and fatigue crack growth tests of 2205 duplex stainless steel (DSS) were performed in laboratory air, gaseous hydrogen at 0.2 MPa and saturated H₂S solution. The longitudinal specimen showed a lesser degradation of tensile properties than the transverse ones in saturated H₂S solution. The orientation of specimens with respect to rolling direction had little influence on the fatigue crack growth rate (FCGR) of the alloy in air. Furthermore, 2205 duplex stainless steel was susceptible to hydrogen‐enhanced fatigue crack growth. Transmission electron micrographs, in addition to X‐ray diffraction, revealed that the strain‐induced austenite to martensite transformation occurred near the crack surface within a rather narrow depth. Fatigue fractography of the specimens tested in air showed mainly transgranular fatigue fracture with a small amount of flat facet fracture. Furthermore, extensive quasi‐cleavage fracture of 2205 duplex stainless steel was associated with the hydrogen‐enhanced crack growth.     

Weighted-averaging-based classification of laser-induced breakdown spectroscopy measurements using most informative spectral lines

In this study, efficient spectral line selection and weighted-averaging-based processing schemes are proposed for the classification of laser-induced breakdown spectroscopy(LIBS) measurements. For fast on-line classification, a set of representative spectral lines are selected and processed relying on the information metric, instead of the time consuming full spectrum based analysis. The most informative spectral line sets are investigated by the joint mutual information estimation(MIE)evaluated with the Gaussian kernel density, where dominant intensity peaks associated with the concentrated components are not necessarily most valuable for classification. In order to further distinguish the characteristic patterns of the LIBS measured spectrum, two-dimensional spectral images are synthesized through column-wise concatenation of the peaks along with their neighbors.For fast classification while preserving the effect of distinctive peak patterns, column-wise Gaussian weighted averaging is applied to the synthesized images, yielding a favorable trade-off between classification performance and computational complexity. To explore the applicability of the proposed schemes, two applications of alloy classification and skin cancer detection are investigated with the multi-class and binary support vector machines classifiers, respectively. The MIE measures associated with selected spectral lines in both applications show a strong correlation to the actual classification or detection accuracy, which enables to find out meaningful combinations of spectral lines. In addition, the peak patterns of the selected lines and their Gaussian weighted averaging with neighbors of the selected peaks efficiently distinguish different classes of LIBS measured spectrum.