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Investigation of the hydraulic performance of a funnel-and-gate permeable reactive barrier (PRB), packed with zero-valent iron (Fe°) and installed at the Vapokon site, Denmark, has been conducted with a natural gradient tracer study. The... more
Investigation of the hydraulic performance of a funnel-and-gate permeable reactive barrier (PRB), packed with zero-valent iron (Fe°) and installed at the Vapokon site, Denmark, has been conducted with a natural gradient tracer study. The purposes of this study were to evaluate the flow pattern and determine the seepage velocity (ν x ) of groundwater through the PRB. After collecting and analysing about 13 000 groundwater samples over a period of 10 months, the moving path of the tracer (i.e. lithium, Li + ) was identified in which the Li + plume was observed passing through the reactive barrier. However, probably owing to clogging caused by mineral precipitates, there was a preferential path inside the Fe 0 PRB. Comparison of the water table contour in the Vapokon site obtained in March 2000 and January 2003 showed formation of a low permeability zone within the reactive barrier, thereby further verifying clogging caused by mineral precipitates. Spatial moments analysis of the Li distribution illustrates the similarity of the maximum Li + mass passing through the upgradient and downgradient locations of the Fe 0 PRB and thereby indicated the conservative of the Li - across the reactive barrier as well as the absence of bypassing flow. Based upon the results of first moment analysis, a ν x of 99.5 m year -1 within the PRB was calculated. The ν x just upgradient of the reactive barrier, however, was only about 6.86 m year -1 , most likely owing to the effect of disturbance exerted by the clogged upgradient interface of the upper part of the Fe 0 PRB.
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A new measurement system called Crosshole Sonic Logging Tomography (CSLT) provides information on the size, shape, and orientation of defects in a bored pile. The CSLT measurement system has not (yet) been accredited in Hong Kong for... more
A new measurement system called Crosshole Sonic Logging Tomography (CSLT) provides information on the size, shape, and orientation of defects in a bored pile. The CSLT measurement system has not (yet) been accredited in Hong Kong for foundation testing. Bored piles in Hong Kong are generally wide and deep. Existing measurement accuracy studies do not consider this large type of bored piles. The objective of this research is to quantify the measurement accuracy and precision of the CSLT method for large diameter bored piles (the most common pile type for public housing projects in Hong Kong). A test pile was constructed with known defects and perform experiments with a CSLT measurement system to quantify its accuracy and precision. CSLT is found to be accurate in detecting shape, size, and location of large defects but small defects close to the tube are difficult to detect. Generally speaking, CSLT has satisfactory accuracy and precision for practical use. The use of CSLT can be con...
Research Interests: Pile and Sonic logging
This book is useful to undergraduate and graduate students in engineering and practicing engineers, as well as educators, scientists, government officials, policymakers, and industrial process managers.
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Z-scheme photocatalyst BiVO4/Ag/g-C3N4 was constructed and applied for rapid disinfection of E. coli cells in water and wastewater.
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This study aimed to maximize the utilization of contaminated marine mud and sediment for beneficial reuse by solidification/stabilization (S/S) treatment with cement and pulverized fuel ash (PFA). For the purposes of waste maximization... more
This study aimed to maximize the utilization of contaminated marine mud and sediment for beneficial reuse by solidification/stabilization (S/S) treatment with cement and pulverized fuel ash (PFA). For the purposes of waste maximization and enhancing the mechanical property of the S/S mixtures, mixing 75% by mass of either contaminated marine mud or sediment with 20% and 5% of cement and PFA, respectively, was found to be the optimal mix design. Their unconfined compressive strengths reached up to 8.32 MPa and 4.47 MPa, respectively. Apart from the mechanical property, according to the U.S.EPA, the TCLP results show that all regulated heavy metals were immobilized to a safe level and are available for engineering application such as fill material. The results of XRD reveal that the formation of CSH gel in the S/S treated mud and sediment is responsible for the strength development and heavy metal immobilization.
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Dechlorination of chlorinated aliphatic hydrocarbons (CAHs) by zero-valent iron (Fe 0 ) was found to be influenced by the competitive effects exerted by other groundwater contaminants. Laboratory column study of the competitive effects on... more
Dechlorination of chlorinated aliphatic hydrocarbons (CAHs) by zero-valent iron (Fe 0 ) was found to be influenced by the competitive effects exerted by other groundwater contaminants. Laboratory column study of the competitive effects on CAH dechlorination by Fe 0 indicated that the presence of 1,1,1-trichloroethane (1,1,1-TCA) in the trichloroethylene (TCE)-contaminated groundwater could decrease the normalized dechlorination rate constant (k SA ) of TCE from 3.04 x 10 -2 to 2.74 x 10 -2 mL m -2 hr -1 . In a similar fashion, introduction of chloroform (TCM) into the synthetic groundwater containing TCE and 1,1,1-TCA led to a 40 to 54% drop in TCE and 1,1,1-TCA k SA , thus indicating competition among TCE, 1,1,1-TCA and TCM during dechlorination reactions induced by Fe 0 . Activation energy ranging from 34.3 to 53.7 kJ/mol for the simultaneous dechlorination of TCE, 1,1,1-TCA and TCM by Fe 0 showed that the process of the electron transfer from Fe 0 to the CAHs is the dominant step limiting the rate of the dechlorination reactions so that the electron released from Fe 0 is most likely in competition with TCE, 1,1,1-TCA and TCM during the dechlorination reactions. In addition to CAHs, abiotic reduction of hexavalent chromium [Cr(VI)] by Fe 0 also exerted effects on TCE dechlorination leading to a 31% drop in TCE k SA after the addition of Cr(VI) into the TCE-contaminated groundwater. Groundwater geochemical factors such as alkalinity and contaminant concentration could potentially influence competition among TCE, 1,1,1-TCA, TCM and Cr(VI) during the abiotic reduction of chemical substances by Fe 0 .
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Research Interests: Materials Science, SEM, Cement, Zinc, Fly Ash, and 4 moreDissolution, XRD, PFA, and Scanning Electron Microscope
Recent studies have shown that hazardous organic dye substances can be removed from aqueous solutions by spinel ferrite nanomaterials. We found that Sodium Dodecyl Sulfonate (SDS) surface-modified mesoporous ZnFe2O4 nanoparticles... more
Recent studies have shown that hazardous organic dye substances can be removed from aqueous solutions by spinel ferrite nanomaterials. We found that Sodium Dodecyl Sulfonate (SDS) surface-modified mesoporous ZnFe2O4 nanoparticles (10-50nm) have a remarkably high maximum adsorptive capacity (∼699.30mg/g) for aqueous Methylene Blue (MB) removal at T of 288K and pH of 12. Unmodified ZnFe2O4 nanoparticles suffer from particle agglomeration, which reduces surface area, thus reducing their adsorptive capacity. Here it is shown that when modified with SDS, the specific surface area increased by ∼34%. It is also shown that the anionic SDS surfactant significantly increased the electrostatic attraction to the cationic MB compound. Moreover, it was found that adsorption of MB positively correlated with the aqueous solution's pH, which is attributed to a stronger negative charge on the SDS modified ZnFe2O4 surface at high pHs. The SDS-modified ZnFe2O4 adsorption of MB fitted well with the ...
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We investigated the mutational landscape of mammalian target of rapamycin (mTOR) signalling cascade in hepatocellular carcinomas (HCCs) with chronic HBV background, aiming to evaluate and delineate mutation-dependent mechanism of mTOR... more
We investigated the mutational landscape of mammalian target of rapamycin (mTOR) signalling cascade in hepatocellular carcinomas (HCCs) with chronic HBV background, aiming to evaluate and delineate mutation-dependent mechanism of mTOR hyperactivation in hepatocarcinogenesis. We performed next-generation sequencing on human HCC samples and cell line panel. Systematic mutational screening of mTOR pathway-related genes was undertaken and mutant genes were evaluated based on their recurrence. Protein expressions of tuberous sclerosis complex (TSC)1, TSC2 and pRPS6 were assessed by immunohistochemistry in human HCC samples. Rapamycin sensitivity was estimated by colony-formation assay in HCC cell lines and the treatment was further tested using our patient-derived tumour xenograft (PDTX) models. We identified and confirmed multiple mTOR components as recurrently mutated in HBV-associated HCCs. Of significance, we detected frequent (16.2%, n=18/111) mutations of TSC1 and TSC2 genes in the...
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This study investigated the effect of acetate and methanol as co-substrates on anaerobic biodegradation of total petroleum hydrocarbons (TPHs, C10-C40) in marine sediment. The findings evidenced that the degradation of TPH can be enhanced... more
This study investigated the effect of acetate and methanol as co-substrates on anaerobic biodegradation of total petroleum hydrocarbons (TPHs, C10-C40) in marine sediment. The findings evidenced that the degradation of TPH can be enhanced by adding acetate or methanol. The addition of acetate was generally more favorable than the addition of methanol for the TPH degradation. Both sulfate reduction and methanogenesis occurred in the acetate-treated sediment. However, the depletion of SO4 (2-) inhibited sulfate reduction over the incubation period. Only methanogenesis was prevalent in the methanol-treated sediment within the whole incubation period. The degradation of TPH fractions with higher carbon number ranges (C31-C40) was speculated to be more favored under sulfate-reducing condition, while TPH fractions with lower carbon number ranges (C10-C20) were preferentially degraded under methanogenic condition. The 16S rRNA clone library-based analysis revealed that the addition of diff...
Research Interests: Chemistry, Metabolism, Petroleum, Biology, Environmental Chemistry, and 15 moreMedicine, Multidisciplinary, Microbial Population Biology, Phylogeny, Methanogenesis, Methanol, Cluster Analysis, Sulfate, HYDROCARBONS, Biostimulation, Biotransformation, Environmental Pollutants, Biota, Geologic Sediments, and Molecular Sequence Data
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This committee report provides a tool for engineers or decision-makers to evaluate the applicability of Zero-valent iron (Fe0) and give them the technical solutions about the engineering application of Fe0 to contaminated sites. Written... more
This committee report provides a tool for engineers or decision-makers to evaluate the applicability of Zero-valent iron (Fe0) and give them the technical solutions about the engineering application of Fe0 to contaminated sites. Written from both theoretical and ...
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... In addition, doping with the appropriate dopant can enhance the photocatalytic efficiency and cause red shift in the band gap of TiO2, making it absorb in the visible range; this technique has been used to make NPs with more... more
... In addition, doping with the appropriate dopant can enhance the photocatalytic efficiency and cause red shift in the band gap of TiO2, making it absorb in the visible range; this technique has been used to make NPs with more photoreactivity (Karn et al., 2005). ...
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Research Interests: Cognitive Science, Biophysics, Electron Microscopy, Long Term Potentiation, Biology, and 15 moreMembrane Proteins, Immunohistochemistry, Medicine, Brain, Dendritic Spines, Humans, Mutagenesis, Mice, Animals, Insects, Lentivirus, Analysis of Variance, Gene Expression Regulation, Excitatory Postsynaptic Potentials, and In Vitro Techniques
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Research Interests: Cardiology, Cardiovascular, Biology, Medicine, Gene expression, and 15 moreSignal Transduction, RNA interference, Humans, Protein Kinases, Mice, Animals, Cell, Male, Protein kinase B, Time Factors, Growth Factor, Recombinant Proteins, CAROTID ARTERY INJURIES, Src family kinases, and Cardiovascular medicine and haematology
ABSTRACT This study examined the transport behavior of nano zero-valent iron (NZVI) coated with three types of stabilizers (i.e., polyacrylic acid, Tween-20, and starch) in saturated sand-and soil-packed columns under varying geochemical... more
ABSTRACT This study examined the transport behavior of nano zero-valent iron (NZVI) coated with three types of stabilizers (i.e., polyacrylic acid, Tween-20, and starch) in saturated sand-and soil-packed columns under varying geochemical conditions. The cations or ionic strength and humic acid (HA) affected the transport of NZVI in varying degrees for different types of surface-modified NZVI (SM-NZVI). The effects of HA on the transport of SM-NZVI were different in sand-and soil-packed columns. In the sand-packed column, the presence of HA exerted an effect on the particle-particle interaction (i.e., aggregation), resulting in either enhanced or decreased transport of SM-NZVI. However, in the soil-packed column, the HA not only influenced the particle-particle interaction but also exerted an effect on the particle-soil grain interaction (i.e., deposition). Additionally, a significant enhancement in the transport of SM-NZVI in the soil-packed column was observed with increasing particle concentration. Moreover, the adsorption of arsenic on the surface of SM-NZVI exhibited insignificant effect on the transport of SM-NZVI. The release of arsenic from the arsenic-loaded SM-NZVI was detected when subjected to flushing with phosphate-containing groundwater. This fundamental understanding of the subsurface transport of SM-NZVI is of critical importance for the benign use and risk management of SM-NZVI.
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Research Interests: Chemistry, Environmental Remediation, Water, Kinetics, Arsenic, and 14 moreWater Purification, PHOTOELECTRON SPECTROSCOPY, Medicine, Multidisciplinary, Adsorption, Nanostructures, Iron, Desorption, X ray diffraction, Fourier transform infrared spectroscopy, Time Factors, Phosphates, Phosphate, and Hydrogen-Ion Concentration
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Renewable Energy Generation by Full-Scale Biomass Gasification System Using Agricultural and Forestal Residues. [Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management 11, 177 (2007)]. Agnes SF ...
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Performance monitoring of applied remediation technologies is an important part of site remediation. It involves periodic measurement of site parameters to evaluate whether the remediation technologies perform as expected or to determine... more
Performance monitoring of applied remediation technologies is an important part of site remediation. It involves periodic measurement of site parameters to evaluate whether the remediation technologies perform as expected or to determine the termination date of remediation projects. Performance monitoring can be a difficult undertaking if there are no well-defined and measurable remediation objectives, such as a reduction in mass discharge rate from a contaminant source. Besides, the selection of the site parameters to be monitored is highly dependent on the remediation objectives established and the remediation technologies applied. For instance, contaminant concentration in soil, soil vapor, and groundwater within a contaminant zone should be monitored if reduction of the mass or volume of a contaminant zone is the prime remediation objective, while contaminant concentration in groundwater just outside a contaminant zone should be the main monitoring parameter if the objective is to mitigate the contami...
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Research Interests: Earth Sciences, Chemistry, Inorganic Chemistry, Arsenic, Water Purification, and 15 moreMedicine, Nuclear Chemistry, Environmental Sciences, Water Supply, Chromium, Iron, Sulfate, CHEMICAL SCIENCES, Arsenite, Hydrogen-Ion Concentration, Ferrous, Arsenates, Arsenate, Removal Efficiency, and chromate conversion coating (CCC)
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Research Interests: Environmental Science, Chemistry, Soil, Kinetics, Transportation, and 14 moreMedicine, Multidisciplinary, Environmental science and technology, Computer Simulation, Copper, Dissolution, Metal, Contaminated soil, Theoretical Models, Lability, Soil Water, Soil Pollutants, Edetic Acid, and Rate Limiting
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... Hydrocarbons. [Journal of Environmental Engineering 133, 859 (2007)]. Keith CK Lai, AMASCE, Irene MC Lo, M.ASCE. Abstract. ... pH measurement was conducted using a flow cell tapped with a pH electrode (9107BN, Orion). concentration ...
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A waste-derived paste of a mixture of paper sludge and tire derived aggregate (TDA) was investigated for daily cover application in municipal solid waste (MSW) landfills. The use of earth materials as daily covers not only consumes... more
A waste-derived paste of a mixture of paper sludge and tire derived aggregate (TDA) was investigated for daily cover application in municipal solid waste (MSW) landfills. The use of earth materials as daily covers not only consumes valuable landfill space, but also creates a series of operating issues. In this study, an experimental testing program was undertaken with the goal of evaluating the mechanical behaviors of the paste based on the findings of the index properties, compressibility, hydraulic conductivity, stress-induced deformation, stress–strain response, and shear resistance of the materials. The mechanical behaviors of the individual TDA, the sludge, as well as the mixture of the two, were evaluated. When compared to traditional soil covers, the proposed paste was: (i) 2–3 times lighter in weight; (ii) at least two orders of magnitude more impermeable; and (iii) comparable in shear resistance. It was also found that with the addition of TDA to the sludge, the shear strength of the paste was improved considerably. The reinforcing mechanisms were explored and quantified, suggesting an optimal TDA content of about 55% by weight. The results from this study indicate that the proposed paste has mechanical characteristics that are desirable for a potential landfill daily cover.