Efflorescence control in geopolymer binders based on natural pozzolan

This paper addresses methods to reduce efflorescence in a geopolymer binder based on a pumice-type natural pozzolanic material from Taftan, Iran. Geopolymer pastes samples are analyzed for compressive strength and efflorescence formation after curing at 95% humidity for 28 days. To reduce the extent of efflorescence, Al-rich mineral admixtures such as metakaolin, ground granulated blast-furnace slag, and three types of calcium aluminate cements are incorporated into the dry binder at a range of concentrations. Hydrothermal curing at elevated temperatures also shows a positive effect in efflorescence reduction. Calcium aluminate cements show the greatest effect in efflorescence reduction, which is attributed to their dissolution in alkaline media releasing high amounts of alumina into the aluminosilicate geopolymer gel. These results confirm that it is possible to develop a more reliable geopolymer binder with improved properties either by adding a suitable amount of active alumina to precursors such as natural pozzolan, or by manipulating the curing conditions to enhance alumina release from less-reactive precursor phases.     

Steam Reforming of Methanol on Copper Catalysts Supported on Large-Surface-Area ZnAl2O3

Steam reforming of methanol on various supported Cu catalysts was examined. Supports strongly affected catalyst activity and, among the catalysts tested, Cu catalyst supported on large-surface-area ZnAl₂O₄ showed the highest activity, which, to the best of our knowledge, was higher than those for the supported catalysts reported so far. For supported Cu catalysts, two species were observed. One was a dispersed Cu species having strong interaction between Cu and support, and the other was an isolated Cu species. The activity of the former species strongly depended on supports.     

Next-generation PON-part III: system specifications for XP-PON

With the knowledge that XG-PON is of primary interest to service providers as their preferred next generation optical access system, the investigation next turns to determining its technical specifications. This article presents the current thinking on the XG-PON systems. It presents a rough outline of the system design for the wavelength plan, the power budget, the protocol, and the management and service model. This work is likely to be the basis for standardization in upcoming ITU-T recommendations.     

Access and metro networks based on WDM technologies

This paper describes the technical issues of access and metro networks based on wavelength division multiplexing (WDM) technologies, some solutions, and an experimental demonstration. A WDM star access network with colorless optical network units (ONUs) is proposed. For realizing the colorless ONU, two approaches are introduced; optical carrier supply and spectrum slicing. In addition, a WDM metro ring network with scalable optical add/drop multiplexers (OADMs), namely the tapped-type OADM, is proposed to effectively accommodate the large amount of traffic issued from access networks. Prototypes are constructed and used to verify the feasibility of the proposed WDM technologies.     

Dipeptidyl peptidase IV from porcine seminal plasma: purification, characterization, and N-terminal amino acid sequence

Dipeptidyl peptidase IV (DPP IV) was purified to homogeneity from porcine seminal plasma by polyacrylamide gel electrophoresis (PAGE). The molecular weight of the purified enzyme was calculated to be approximately 290,000 on PAGE in the absence of sodium dodecyl sulfate (SDS) and 310,000 on Sephacryl S-300 HR column chromatography, and to be 115,000 and 105,000 on SDS-PAGE in the absence and presence of beta-mercaptoethanol. The enzyme is suggested to be composed of three identical subunits. The enzyme rapidly hydrolyzed the substrate Gly-Pro-MCA, and weakly the substrate Lys-Ala-MCA. It was strongly inhibited by diisopropylphosphofluoridate (DFP), and moderately by both phenylmethyl-sulfonyl fluoride (PMSF) and 4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF). It was also strongly inhibited by zinc ion. The amino acid sequence of the first 18 residues of the enzyme was Asn-Lys-Gly-Thr-Asp-Asp-Ala-Ala-Ala-Asp-Ser-Arg-Arg- Thr-Tyr-Thr-Leu-Thr-. This sequence was highly homologous to the sequences in the rear of the transmembrane site of human and rat liver DPP IVs and mouse thymus DPP IV. The native DPP IV is suggested to be released into the seminal plasma after the cleavage of the hydrophobic N-terminal domain by chymotrypsin-like or pepsin-like enzymes. Other properties of DPP IV including kinetic parameters, pH stability and heat stability were characterized.     

Scalability of spectrum-sliced DWDM transmission and its expansion using forward error correction

This paper clarifies the scalability of spectrum-sliced dense wavelength-division-multiplexing (DWDM) transmission systems primarily intended for metro access applications. A theoretical analysis elucidates the tradeoff between the loss budget and the sliced bandwidth (i.e., the number of channels with assuming light sources with a fixed bandwidth). Moreover, the use of forward error correction (FEC) to expand scalability is studied. Based on the analysis, two spectrum-sliced DWDM transmission schemes are introduced. One demonstrates 1.25-Gb/s, eight channel spectrum-sliced DWDM transmission through the use of directly modulated super-luminescent diodes (SLDs), and the other confirms 10-Gb/s, eight channel spectrum-sliced DWDM transmission with the channel spacing of 200 GHz through the use of FEC.     

Curvature-based stroke rendering

This paper describes an algorithm that renders lines that have various thicknesses and have sharp tapered ends. This algorithm does not require any special information on each local point of a line. The thickness is determined by curvature and lengths from both ends. Therefore the algorithm is applicable in a variety of line rendering situations, such as 3D rendering engines for high quality cel-animation-like effects, reuse of geometrical data designed by CAD for advertising purposes, edge enhancement in a photo retouching process with edge detection methods and so on. In addition, using the generated varying thicknesses, we have developed algorithms for shading and embossing effects.