Synthesis and interfacial behaviors of amphiphilic poly(oxypropylene) amidoacids

A series of hydrophobic poly(oxypropylene) (POP)-backboned and hydrophilic poly(oxyethylene)-backboned amidoacids and imidoacids were prepared through the reaction of poly(oxyalkylene) diamines and trimellitic anhydride (TMA) under mild conditions. The synthesized copolymers were characterized with nuclear magnetic resonance and Fourier transform infrared. Their ability to lower the water surface tension and toluene/water interfacial tension was measured and correlated with the hydrophobic/hydrophilic balance with multiple sodium carboxylate functionalities. The specific POP2000/TMA copolymers, consisting of a 2000 g/mol POP segment and multiple amidoacid functionalities, enabled the demonstration of a strong surfactant tendency and a critical micelle concentration at 0.1 wt %. (c) 2005 Wiley Periodicals, Inc

A landslide dam breach induced debris flow - a case study on downstream hazard areas delineation

A catastrophic landslide dam breach induced debris flow initiated in Da-Cu-Keng stream, Ruifang town, when typhoon Xangsane hit Taiwan on November 1, 2000. Different available methodologies were used to model the natural dam breach induced debris flow and using field topography the hazard zones affected by debris mixtures were delineated. The numerical finite element or finite difference method is time consuming for the simulation of debris flow inundation areas and hence a rules-based GIS (Geographic Information System) analysis is proposed in this study. The model emphasizes the downstream inundated fan-shaped areas covered by debris mixtures through the overflow point. Topography and gradient are assumed to dominate the debris masses deposition mechanism in the GIS analysis. The approach considers the parameters' effects, such as the runout distance, the debris masses magnitude and the inundated areas. The results of this study reveal that the GIS process using the rule-based approach speeds up the processing of delineating the hazard zones and assessment, which can be applied to early-warning and preliminary inundation hazardous mapping

A GIS process for delimitating areas potentially endangered by debris flow

A GIS rules-based approach is proposed for delimiting areas potentially endangered by debris flow for downstream guarded areas. Data were used to define rules for nine pilot areas in the Chen-You-Lan river watershed in Nantou County of Taiwan. A preliminary regressed relationship between debris volume and runout distance in the pilot areas is first formulated. The GIS processes for applying the rules are linked to delimit hazardous areas affected by debris within the first approximated debris fan. Rules applied to delimit potentially endangered areas incorporate geomorphological factors (gradient or curvature, aspect), direction of flow, fan angle of the debris and location of the overflow points. The delimited zone is then calibrated using the regression formula for debris volume against the affected area. The verification of the delineation of the areas using the adopted approach, with reference to micro-geomorphological results concerning pilot cases validates the proposed model. The model can be used to delineate potentially hazardous zones approximately associated with debris flow in rivers in Taiwan

Dark fermentative hydrogen production from xylose in different bioreactors using sewage sludge microflora

In this study, the H-2-producing activity of the sewage sludge microflora using xylose as the sole carbon substrate was investigated in three bioreactor systems, including a suspended continuously stirred tank reactor (CSTR), an immobilized-cell continuously stirred anaerobic bioreactor (IC-CSABR), and a powder activated carbon-assisted agitated granular sludge bed (AGSB). For suspended-culture CSTR operations, fermentative H-2 production was conducted at different hydraulic retention times (HRT=4 - 12 h). The H-2 production rate (HPR) was 183 mmol/L/d at HRT = 12 h, but the H-2 production rate and yield decreased significantly when the HRT was shortened to 4 h due primarily to the washout of cells. To improve the operational stability of short HRTs, silicone-immobilized cells (IC-CSABR system) and powder activated carbon carriers (AGSB system) were adopted for the reactor systems to either maintain stable biomass concentration in the reactor or enhance biomass content by stimulating sludge granulation. Both IC-CSABR and AGSB showed improved biomass retention while operating at a HRT of 4 h. In particular, the biomass content in the IC-CSABR system (HRT = 2 h) went up to 8.03 g of VSS/L, leading to a drastic enhancement in the H2 production rate (1.06 mol/L/d). Bacterial community analysis by denatured gradient gel electrophoresis (DGGE) indicates a transition in bacterial composition in the CSTR under different HRT conditions. Moreover, under the same HRT (4 h), the major bacterial populations in the AGSB and IC-CSABR reactors were very different from those observed in the CSTR, indicating that the performance of H-2 production seemed to be in close connection with the bacterial community structure. Several H-2-producing bacterial strains (e.g., Clostridium butyricum and Klebsiella pneumoniae) were also detected in the sludge samples by DGGE and 16S rDNA sequence matching, revealing the effectiveness of the H-2-producing sludge used in this study