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Foster Brook, PA, United States

Seliem M.K.,Pennsylvania State University | Seliem M.K.,Beni Suef University | Komarneni S.,Pennsylvania State University | Parette R.,Matson and Associates Inc. | And 5 more authors.
Applied Clay Science | Year: 2011

A variety of oraganosilicas such as MCM-41 and MCM-48 and composites of rice husks with MCM-48 were synthesized under an array of conditions and characterized by powder X-ray diffraction (XRD). Various MCM-41 mesoporous materials were prepared at room temperature using different surfactants. MCM-48 silica and its composites with rice husks were synthesized under hydrothermal conditions using cetyltrimethylammonium (CTMA) bromide and rice husks. Both untreated and carbonized rice husks were used for preparing composites of rice husk with MCM-48. Organo-clay minerals procured from two commercial sources were also investigated for their perchlorate uptake. Among the MCM-41 materials, the sample prepared from octadecyltrimethylammonium (ODTMA) chloride showed the highest perchlorate uptake capacity of 0.227 ± 0.006. meq/g while MCM-48 showed the highest perchlorate uptake capacity of 0.437 ± 0.011. meq/g among all the oraganosilicas and organo-clay minerals tested here. The uptake of perchlorate by organosilicas and organo-clay minerals is due to residual positive charge on the surfactants located in the mesopores of organosilicas and interlayers of organo-clay minerals. © 2011 Elsevier B.V. Source

Seliem M.K.,Pennsylvania State University | Seliem M.K.,Beni Suef University | Komarneni S.,Pennsylvania State University | Parette R.,Matson and Associates Inc. | And 5 more authors.
Materials Research Innovations | Year: 2010

Mesoporous MCM-41 silica and rice husk composites were synthesised under hydrothermal conditions using cetyltrimethylammonium bromide (CTAB) as an organic template, aqueous ammonia solution (NH4OH) and rice husk, the latter as a silica source and substrate for the deposition of MCM-41. Both untreated and carbonised rice husks were used for preparing composites at a temperature of 100-120°C for 24-48 h. The as synthesised composites or hybrid materials were characterised by using XRD and SEM and they were found to be useful for the uptake of perchlorate. These composites could be used to separate perchlorate from solutions in column operation without the necessity for their pelletisation because the rice husk substrates are several millimetres in size. © 2010 W. S. Maney & Son Ltd. Source

Stone M.C.,University of New Mexico | Chen L.,Desert Research Institute | Kyle Mckay S.,U.S. Army | Goreham J.,Matson and Associates Inc. | And 3 more authors.
River Research and Applications | Year: 2013

Woody riparian vegetation provides numerous ecological benefits such as stabilizing streambanks, storing and cycling nutrients, shading streams and providing habitat for wildlife. However, vegetation also increases hydraulic roughness and reduces the effective flow area, resulting in an increased water surface elevation for a given streamflow. Balancing the desire to preserve woody vegetation in stream corridors with the need to manage flood risks requires accurate techniques for predicting the influence of vegetation on stream hydraulics. However, this is a challenging problem because woody vegetation responds to the flow field itself by bending and streamlining in response to hydraulic forces. The goal of this study was to predict the bending behaviour of woody riparian vegetation as a function of hydraulic flow conditions. Field tests were performed to elucidate tree biomechanical properties for select riparian taxa of the southwestern USA. Biomechanical results served as input parameters for a numerical algorithm designed to predict tree bending for water velocities likely to be encountered during flood events. Bending simulations revealed appreciable variability in bent tree heights. Variability was likely a manifestation of the extensive variance in plant characteristics and properties inherent in biological specimens. However, no trees were expected to bend to a height lower than approximately 42% of their original height, even in water moving at 2.5m·s-1. The results of this work provide an important first step in an effort to predict a dynamic hydraulic roughness for vegetated channels and floodplains under flood conditions. © 2011 John Wiley & Sons, Ltd. Source

Kim J.Y.,Pennsylvania State University | Komarneni S.,Pennsylvania State University | Parette R.,Matson and Associates Inc. | Cannon F.,Pennsylvania State University | Katsuki H.,Saga Ceramic Research Laboratory
Applied Clay Science | Year: 2011

The perchlorate uptake of hydrotalcite- and hydrocalumite-type layered double hydroxides (LDHs), and surfactant modified clay minerals were compared. Perchlorate uptake by both hydrotalcite- and hydrocalumite-type LDHs was in the range of 0.011 to 0.197 meq/g from a 2 mM perchlorate solution. The nitrate form of Mg:Al LDH had the highest uptake of 0.197 ± 0.033 meq/g, and the carbonate form of LDH the lowest uptake of 0.011 ± 0.003 meq/g. Octadecyltrimethylammonium (ODTMA), Dodecyltrimethylammonium (DoDTMA), and hexadecyltrimethylammonium (HDTMA) clay minerals removed perchlorate in the range of 0.025 to 0.348 meq/g from a 2 mM perchlorate solution. Synthetic HDTMA (5.0 CEC) Na-1-mica exhibited the highest adsorption of perchlorate with 0.348 ± 0.011 meq/g, while DoDTMA montmorillonite had the lowest adsorption with 0.025 ± 0.009 meq/g. Tested under the same conditions, a surfactant modified carbon showed an uptake of 0.303 ± 0.005 meq/g and this carbon is currently being used for filtration of drinking water.Hydrophobic organo-clay minerals with larger interlayer distance resulted in higher perchlorate uptake by exchange/adsorption on the residual charge of the cationic surfactants. The uptake by LDH was by anion exchange on the surfaces and, for the nitrate form of hydrotalcite, also from the interlayer spaces. The mechanisms of uptake were confirmed by X-ray diffraction (XRD) and scanning electron microscopy. This study indicated that cationic surfactant containing organo-clay minerals may be useful materials for the removal of perchlorate from water and could serve as alternatives to surfactant modified-activated carbons. © 2010 Elsevier B.V. Source

Riddell N.,Wellington Laboratories Inc. | Jin U.-H.,Texas A&M University | Safe S.,Texas A&M University | Cheng Y.,Texas A&M University | And 12 more authors.
Environmental Science and Technology | Year: 2015

This paper deals with the characterization and aryl hydrocarbon receptor (AhR) agonist activities of a series of chlorinated, brominated, and mixed bromo/chlorocarbazoles, some of which have been identified in various environmental samples. Attention is directed here to the possibility that halogenated carbazoles may currently be emitted into the environment as a result of the production of carbazole-containing polymers present in a wide variety of electronic devices. We have found that any carbazole that is not substituted in the 1,3,6,8 positions may be lost during cleanup of environmental extracts if a multilayer column is utilized, as is common practice for polychlorinated dibenzo-p-dioxin (dioxin) and related compounds. In the present study, 1H NMR spectral shift data for 11 relevant halogenated carbazoles are reported, along with their gas chromatographic separation and analysis by mass spectrometry. These characterization data allow for confident structural assignments and the derivation of possible correlations between structure and toxicity based on the halogenation patterns of the isomers investigated. Some halogenated carbazoles exhibit characteristics of persistent organic pollutants and their potential dioxin-like activity was further investigated. The structure-dependent induction of CYP1A1 and CYP1B1 gene expression in Ah-responsive MDA-MB-468 breast cancer cells by these carbazoles was similar to that observed for other dioxin-like compounds, and the magnitude of the fold induction responses for the most active halogenated carbazoles was similar to that observed for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). 2,3,6,7-Tetrachlorocarbazole was one of the most active halogenated carbazoles and, like TCDD, contains 4 lateral substituents; however, the estimated relative effect potency for this compound (compared to TCDD) was 0.0001 and 0.0032, based on induction of CYP1A1 and CYP1B1 mRNA, respectively. (Graph Presented). © 2015 American Chemical Society. Source

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