A series of novel organic-inorganic hybrid membranes with special microstructure, based on sulfon... more A series of novel organic-inorganic hybrid membranes with special microstructure, based on sulfonated poly (fluorenyl ether ketone) ionomer (SFPEK, IEC = 1.92 mequiv. g −1 ) and SiO 2 or sulfonic acid group containing SiO 2 (SiO 2 -SO 3 H), has been successfully designed and prepared for vanadium redox flow battery (VRB) application. The SiO 2 -SO 3 H is synthesized by co-condensation of tetraethoxysilane and ␥-propyl mercaptotrimethoxysilane via sol-gel process to control the same IEC with neat SPFEK. The hybrid membranes are prepared by simply adding the inorganic particles into the SPFEK solution in N,Ndimethylacetamide, followed by ultrasonic dispersion, casting and profiled temperature drying process. The morphology is examined by SEM-EDX which is applied to the top surface, bottom surface and crosssection of the hybrid membranes. The water uptake, oxidative stability, thermal property, mechanical property, proton conductivity, VO 2+ permeability and single cell performance are investigated in detail in order to understand the relationship between morphology and property of the membranes. All the hybrid membranes show dramatically improved proton selectivity at 20 • C and 40 • C when compared with Nafion117. The VRB assembled with the SPFEK/3%SiO 2 and SPFEK/9%SiO 2 membranes exhibit higher coulombic efficiency and average discharge voltage than the VRB assembled with the SPFEK membrane at all the tested current densities.
Environmental isotopes and water quality indicators (e.g. TDS and NO 3 contents) were used to cha... more Environmental isotopes and water quality indicators (e.g. TDS and NO 3 contents) were used to characterize the age, recharge history and controls on the quality of groundwater resources in the Yuncheng Basin, north China, where extensive extraction occurs for agriculture and domestic supply. d 18 O and d 2 H values as low as À10.6‰ and À73‰, respectively, together with low radiocarbon activities (<20 pmC) show that deep groundwater comprises palaeowaters largely recharged in the late Pleistocene ($10 to 22 ka B.P.) under a cooler climate than the present. Shallow groundwater has higher radiocarbon activities (>70 pmC), indicating a significant component of modern (post-1950s) recharge. The shallow groundwater has higher d 18 O and d 2 H values (up to À8.1‰ and À54‰) that are similar to those in modern summer monsoon rainfall, indicating that current recharge is via direct infiltration and/or leakage of ephemeral streams during heavy rain events. Historic recharge rates estimated using radiocarbon ages are between 1 and 10 mm/year, corresponding to <2% of local rainfall, which is lower than estimates of modern recharge nearby based on tritium data. The relationship between groundwater d 18 O values and 14 C ages is similar to that observed in groundwater from other basins in northern China, confirming that much deep groundwater in the region is palaeowater, and suggesting that a broad scale assessment of groundwater residence times may be made from d 18 O and d 2 H values. Most deep groundwater has low TDS and nitrate concentrations (median 1090 mg/L and 1.8 mg/L, respectively), while shallow groundwater has TDS contents of up to 8450 mg/L (median 2010 mg/L) and NO 3 concentrations up to 630 mg/L (median 31 mg/L). A lack of enrichment in d 18 O values in the high salinity shallow groundwater indicates that transpiration by crops and possibly minor mineral dissolution are the major salinisation processes, rather than evaporation or leakage from salt lakes. The majority of nitrate in groundwater has d 15 N NO3 values between 0.8‰ and 5.0‰ and d 18 O NO3 values between 1.8‰ and 4.1‰, indicating that synthetic fertilizers are the main source of elevated NO 3 concentrations. Increasing residence times from east-to-west in deep groundwaters reflect the historic regional flow pattern in the basin. However, present-day flow is now dictated by a large cone of depression that has formed due to intensive deep groundwater pumping since the 1980s. High downward vertical hydraulic gradients (up to 0.45) have also developed as a result of this pumping, promoting downwards leakage of shallow water, indicated by high nitrate concentrations (>20 mg/L) in some deep wells (>180 m). Preferential leakage has occurred near the Linyi fault, in the northern Sushui River Basin. Salinisation, nitrate contamination and excessive drawdown of deep groundwater are major concerns for the future of the groundwater resources in this region.
Based on analysis of groundwater hydrochemical and isotopic indicators, this article aims to iden... more Based on analysis of groundwater hydrochemical and isotopic indicators, this article aims to identify the groundwater flow systems in the Yangwu River alluvial fan, in the Xinzhou Basin, China. Groundwater δ2H and δ18O values indicate that the origin of groundwater is mainly from precipitation, with local evaporative influence. d-excess values lower than 10% in most groundwaters suggest a cold climate during recharge in the area. Major ion chemistry, including rCa/rMg and rNa/rCl ratios, show that groundwater salinization is probably dominated by water–rock interaction (e.g., silicate mineral weathering, dissolution of calcite and dolomite and cation exchange) in the Yangwu River alluvial fan, and locally by intensive evapotranspiration in the Hutuo River valley. Cl and Sr concentrations follow an increasing trend in shallow groundwater affected by evaporation, and a decreasing trend in deep groundwater. 87Sr/86Sr ratios reflect the variety of lithologies encountered during throughflow. The groundwater flow systems (GFS) of the Yangwu River alluvial fan include local and intermediate flow systems. Hydrogeochemical modeling results, simulated using PHREEQC, reveal water–rock interaction processes along different flow paths. This modeling method is more effective for characterizing flow paths in the intermediate system than in the local system. Artificial exploitation on groundwater in the alluvial fan enhances mixing between different groundwater flow systems.
With the goal of developing small molecules as novel regulators of signal transduction and apopto... more With the goal of developing small molecules as novel regulators of signal transduction and apoptosis, a series of tyrphostin-like compounds were synthesized and screened for their activity against MM-1 (multiple myeloma) cells and other cell lines representing this malignancy. Synthesis was completed in solution-phase initially and then adopted to solid-phase for generating a more diverse set of compounds. A positive correlation was noted between compounds capable of inducing apoptosis and their modulation of protein ubiquitination. Further analysis suggested that ubiquitin modulation occurs through inhibition of cellular deubiquitinase activity. Bulky groups on the sidechain near the a,b-unsaturated ketone caused a complete loss of activity, whereas cyclization on the opposite side was tolerated. Theoretical calculations at the B3LYP/LACV3P ⁄⁄ level were completed on each molecule, and the resulting molecular orbitals and Fukui reactivity values for C b carbon were utilized in developing a model to explain the compound activity.
The first synthesis of bivalent ligands of b-carboline-3-carboxylates has been achieved from b-ca... more The first synthesis of bivalent ligands of b-carboline-3-carboxylates has been achieved from b-carboline-3-carboxylate tert-butyl ester (bCCt) via Sonogashira and palladium-catalyzed homocoupling processes. The Boc protected intermediate, an iodo-b-carboline-3-carboxylate, was employed to provide a general entry into a series of bivalent ligands structurally similar to bCCt.
The stable conformations of both the trans- and cis-1,3-disubstituted Nb-benzyl stereoisomers of ... more The stable conformations of both the trans- and cis-1,3-disubstituted Nb-benzyl stereoisomers of the Pictet - Spengler reaction have been determined by NMR spectroscopy and X-ray crystallography in order to better understand the C(1) -N(2) cis- to trans-isomerization process. In the Na-H series, the chair conformation was preferred for the trans-isomer 3a, while the cis-isomer 3b existed predominantly in the boat form. However, in the Na-methyl series (1a, 1b, 2a, 2b), both the cis (1b, 2b) and trans (1a, 2a) diastereomers existed in the chair conformation to relieve the A(1,2)-strain between the Na-methyl function and the substituent at C(1). The difference in the preferred conformations of the cis-isomers in the Na-H and Na-methyl series (as compared to the preferred conformations in the trans-isomers) can be employed to understand the reduced rate of epimerization of cis-2b into trans-2a as compared to 3b into 3a. This provides the structural basis for the carbocation-mediated intermediate in the C(1) - N(2) scission process.
The first enantiospecific total synthesis of gardnerine and gardnutine has been achieved from 6-m... more The first enantiospecific total synthesis of gardnerine and gardnutine has been achieved from 6-methoxy-D D-tryptophan via the asymmetric Pictet-Spengler reaction, a stereocontrolled intramolecular enolate driven palladium-mediated cross-coupling reaction and a chemospecific, regiospecific hydroboration/oxidation sequence as key steps.
The stable conformations of GABA A -benzodiazepine receptor bivalent ligands were determined by l... more The stable conformations of GABA A -benzodiazepine receptor bivalent ligands were determined by low temperature NMR spectroscopy and confirmed by single crystal X-ray analysis. The stable conformations in solution correlated well with those in the solid state. The linear conformation was important for these dimers to access the binding site and exhibit potent in vitro affinity and was illustrated for a5 subtype selective ligands. Bivalent ligands with an oxygen-containing linker folded back upon themselves both in solution and the solid state. Dimers which are folded do not bind to Bz receptors.
A series of novel organic-inorganic hybrid membranes with special microstructure, based on sulfon... more A series of novel organic-inorganic hybrid membranes with special microstructure, based on sulfonated poly (fluorenyl ether ketone) ionomer (SFPEK, IEC = 1.92 mequiv. g −1 ) and SiO 2 or sulfonic acid group containing SiO 2 (SiO 2 -SO 3 H), has been successfully designed and prepared for vanadium redox flow battery (VRB) application. The SiO 2 -SO 3 H is synthesized by co-condensation of tetraethoxysilane and ␥-propyl mercaptotrimethoxysilane via sol-gel process to control the same IEC with neat SPFEK. The hybrid membranes are prepared by simply adding the inorganic particles into the SPFEK solution in N,Ndimethylacetamide, followed by ultrasonic dispersion, casting and profiled temperature drying process. The morphology is examined by SEM-EDX which is applied to the top surface, bottom surface and crosssection of the hybrid membranes. The water uptake, oxidative stability, thermal property, mechanical property, proton conductivity, VO 2+ permeability and single cell performance are investigated in detail in order to understand the relationship between morphology and property of the membranes. All the hybrid membranes show dramatically improved proton selectivity at 20 • C and 40 • C when compared with Nafion117. The VRB assembled with the SPFEK/3%SiO 2 and SPFEK/9%SiO 2 membranes exhibit higher coulombic efficiency and average discharge voltage than the VRB assembled with the SPFEK membrane at all the tested current densities.
Environmental isotopes and water quality indicators (e.g. TDS and NO 3 contents) were used to cha... more Environmental isotopes and water quality indicators (e.g. TDS and NO 3 contents) were used to characterize the age, recharge history and controls on the quality of groundwater resources in the Yuncheng Basin, north China, where extensive extraction occurs for agriculture and domestic supply. d 18 O and d 2 H values as low as À10.6‰ and À73‰, respectively, together with low radiocarbon activities (<20 pmC) show that deep groundwater comprises palaeowaters largely recharged in the late Pleistocene ($10 to 22 ka B.P.) under a cooler climate than the present. Shallow groundwater has higher radiocarbon activities (>70 pmC), indicating a significant component of modern (post-1950s) recharge. The shallow groundwater has higher d 18 O and d 2 H values (up to À8.1‰ and À54‰) that are similar to those in modern summer monsoon rainfall, indicating that current recharge is via direct infiltration and/or leakage of ephemeral streams during heavy rain events. Historic recharge rates estimated using radiocarbon ages are between 1 and 10 mm/year, corresponding to <2% of local rainfall, which is lower than estimates of modern recharge nearby based on tritium data. The relationship between groundwater d 18 O values and 14 C ages is similar to that observed in groundwater from other basins in northern China, confirming that much deep groundwater in the region is palaeowater, and suggesting that a broad scale assessment of groundwater residence times may be made from d 18 O and d 2 H values. Most deep groundwater has low TDS and nitrate concentrations (median 1090 mg/L and 1.8 mg/L, respectively), while shallow groundwater has TDS contents of up to 8450 mg/L (median 2010 mg/L) and NO 3 concentrations up to 630 mg/L (median 31 mg/L). A lack of enrichment in d 18 O values in the high salinity shallow groundwater indicates that transpiration by crops and possibly minor mineral dissolution are the major salinisation processes, rather than evaporation or leakage from salt lakes. The majority of nitrate in groundwater has d 15 N NO3 values between 0.8‰ and 5.0‰ and d 18 O NO3 values between 1.8‰ and 4.1‰, indicating that synthetic fertilizers are the main source of elevated NO 3 concentrations. Increasing residence times from east-to-west in deep groundwaters reflect the historic regional flow pattern in the basin. However, present-day flow is now dictated by a large cone of depression that has formed due to intensive deep groundwater pumping since the 1980s. High downward vertical hydraulic gradients (up to 0.45) have also developed as a result of this pumping, promoting downwards leakage of shallow water, indicated by high nitrate concentrations (>20 mg/L) in some deep wells (>180 m). Preferential leakage has occurred near the Linyi fault, in the northern Sushui River Basin. Salinisation, nitrate contamination and excessive drawdown of deep groundwater are major concerns for the future of the groundwater resources in this region.
Based on analysis of groundwater hydrochemical and isotopic indicators, this article aims to iden... more Based on analysis of groundwater hydrochemical and isotopic indicators, this article aims to identify the groundwater flow systems in the Yangwu River alluvial fan, in the Xinzhou Basin, China. Groundwater δ2H and δ18O values indicate that the origin of groundwater is mainly from precipitation, with local evaporative influence. d-excess values lower than 10% in most groundwaters suggest a cold climate during recharge in the area. Major ion chemistry, including rCa/rMg and rNa/rCl ratios, show that groundwater salinization is probably dominated by water–rock interaction (e.g., silicate mineral weathering, dissolution of calcite and dolomite and cation exchange) in the Yangwu River alluvial fan, and locally by intensive evapotranspiration in the Hutuo River valley. Cl and Sr concentrations follow an increasing trend in shallow groundwater affected by evaporation, and a decreasing trend in deep groundwater. 87Sr/86Sr ratios reflect the variety of lithologies encountered during throughflow. The groundwater flow systems (GFS) of the Yangwu River alluvial fan include local and intermediate flow systems. Hydrogeochemical modeling results, simulated using PHREEQC, reveal water–rock interaction processes along different flow paths. This modeling method is more effective for characterizing flow paths in the intermediate system than in the local system. Artificial exploitation on groundwater in the alluvial fan enhances mixing between different groundwater flow systems.
With the goal of developing small molecules as novel regulators of signal transduction and apopto... more With the goal of developing small molecules as novel regulators of signal transduction and apoptosis, a series of tyrphostin-like compounds were synthesized and screened for their activity against MM-1 (multiple myeloma) cells and other cell lines representing this malignancy. Synthesis was completed in solution-phase initially and then adopted to solid-phase for generating a more diverse set of compounds. A positive correlation was noted between compounds capable of inducing apoptosis and their modulation of protein ubiquitination. Further analysis suggested that ubiquitin modulation occurs through inhibition of cellular deubiquitinase activity. Bulky groups on the sidechain near the a,b-unsaturated ketone caused a complete loss of activity, whereas cyclization on the opposite side was tolerated. Theoretical calculations at the B3LYP/LACV3P ⁄⁄ level were completed on each molecule, and the resulting molecular orbitals and Fukui reactivity values for C b carbon were utilized in developing a model to explain the compound activity.
The first synthesis of bivalent ligands of b-carboline-3-carboxylates has been achieved from b-ca... more The first synthesis of bivalent ligands of b-carboline-3-carboxylates has been achieved from b-carboline-3-carboxylate tert-butyl ester (bCCt) via Sonogashira and palladium-catalyzed homocoupling processes. The Boc protected intermediate, an iodo-b-carboline-3-carboxylate, was employed to provide a general entry into a series of bivalent ligands structurally similar to bCCt.
The stable conformations of both the trans- and cis-1,3-disubstituted Nb-benzyl stereoisomers of ... more The stable conformations of both the trans- and cis-1,3-disubstituted Nb-benzyl stereoisomers of the Pictet - Spengler reaction have been determined by NMR spectroscopy and X-ray crystallography in order to better understand the C(1) -N(2) cis- to trans-isomerization process. In the Na-H series, the chair conformation was preferred for the trans-isomer 3a, while the cis-isomer 3b existed predominantly in the boat form. However, in the Na-methyl series (1a, 1b, 2a, 2b), both the cis (1b, 2b) and trans (1a, 2a) diastereomers existed in the chair conformation to relieve the A(1,2)-strain between the Na-methyl function and the substituent at C(1). The difference in the preferred conformations of the cis-isomers in the Na-H and Na-methyl series (as compared to the preferred conformations in the trans-isomers) can be employed to understand the reduced rate of epimerization of cis-2b into trans-2a as compared to 3b into 3a. This provides the structural basis for the carbocation-mediated intermediate in the C(1) - N(2) scission process.
The first enantiospecific total synthesis of gardnerine and gardnutine has been achieved from 6-m... more The first enantiospecific total synthesis of gardnerine and gardnutine has been achieved from 6-methoxy-D D-tryptophan via the asymmetric Pictet-Spengler reaction, a stereocontrolled intramolecular enolate driven palladium-mediated cross-coupling reaction and a chemospecific, regiospecific hydroboration/oxidation sequence as key steps.
The stable conformations of GABA A -benzodiazepine receptor bivalent ligands were determined by l... more The stable conformations of GABA A -benzodiazepine receptor bivalent ligands were determined by low temperature NMR spectroscopy and confirmed by single crystal X-ray analysis. The stable conformations in solution correlated well with those in the solid state. The linear conformation was important for these dimers to access the binding site and exhibit potent in vitro affinity and was illustrated for a5 subtype selective ligands. Bivalent ligands with an oxygen-containing linker folded back upon themselves both in solution and the solid state. Dimers which are folded do not bind to Bz receptors.
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