Yong Huang - Academia.edu (original) (raw)
Papers by Yong Huang
Journal of hazardous materials, Jan 30, 2015
Magnetic imprinted polymers (MIPs) were synthesized by Pickering emulsion polymerization and used... more Magnetic imprinted polymers (MIPs) were synthesized by Pickering emulsion polymerization and used to adsorb erythromycin (ERY) from aqueous solution. The oil-in-water Pickering emulsion was stabilized by chitosan nanoparticles with hydrophobic Fe3O4 nanoparticles as magnetic carrier. The imprinting system was fabricated by radical polymerization with functional and crosslinked monomer in the oil phase. Batches of static and dynamic adsorption experiments were conducted to analyze the adsorption performance on ERY. Isotherm data of MIPs well fitted the Freundlich model (from 15°C to 35°C), which indicated heterogeneous adsorption for ERY. The ERY adsorption capacity of MIPs was about 52.32μmol/g at 15°C. The adsorption kinetics was well described by the pseudo-first-order model, which suggested that physical interactions were primarily responsible for ERY adsorption. The Thomas model used in the fixed-bed adsorption design provided a better fit to the experimental data. Meanwhile, ER...
PloS one, 2014
Spider venom comprises a mixture of compounds with diverse biological activities, which are used ... more Spider venom comprises a mixture of compounds with diverse biological activities, which are used to capture prey and defend against predators. The peptide components bind a broad range of cellular targets with high affinity and selectivity, and appear to have remarkable structural diversity. Although spider venoms have been intensively investigated over the past few decades, venomic strategies to date have generally focused on high-abundance peptides. In addition, the lack of complete spider genomes or representative cDNA libraries has presented significant limitations for researchers interested in molecular diversity and understanding the genetic mechanisms of toxin evolution. In the present study, second-generation sequencing technologies, combined with proteomic analysis, were applied to determine the diverse peptide toxins in venom of the Chinese bird spider Ornithoctonus huwena. In total, 626 toxin precursor sequences were retrieved from transcriptomic data. All toxin precursor...
ONE HUNDRED AND FIVE PATIENTS WITH PRIMARY UNIPOLAR DEPRESSION WERE RANDOMLY DIVIDED INTO THREE G... more ONE HUNDRED AND FIVE PATIENTS WITH PRIMARY UNIPOLAR DEPRESSION WERE RANDOMLY DIVIDED INTO THREE GROUPS: drug group (Seroxat administration), acupuncture group (Seroxat plus acupuncture), and electroacupuncture group (Seroxat plus acupuncture plus electroacupuncture). Patients' symptoms were evaluated using a psychometric questionnaire, the Symptom Checklist-90, before intervention and after 2, 4, 6 and 10 weeks of treatment. The individual factor scores and the total score from the Symptom Checklist-90 reduced in all three groups as treatment progressed. In the acupuncture and electroacupuncture groups, the total score and the factor scores for obsessive-compulsive symptoms, depression, and anxiety were significantly lower than those in the drug group. There was no significant difference in the factor scores or total scores between the acupuncture and electroacupuncture groups. Some factor scores in the electroacupuncture group, such as somatization, depression, hostility, and phobic anxiety, were increased at 10 weeks compared with the respective score immediately after the course of electroacupuncture at 6 weeks. Our findings indicate that administration of Seroxat alone or in combination with acupuncture/electroacupuncture can produce a significant effect in patients with primary unipolar depression. Furthermore, acupuncture/electroacupuncture has a rapid onset of therapeutic effect and produces a noticeable improvement in obsessive-compulsive, depressive and anxiety symptoms.
We propose and demonstrate strain-balanced InAs/GaSb type-II superlattices (T2SLs) grown on InAs ... more We propose and demonstrate strain-balanced InAs/GaSb type-II superlattices (T2SLs) grown on InAs substrates employing GaAs-like interfacial (IF) layers by metalorganic chemical vapor deposition (MOCVD) for effective strain management, simplified growth scheme, improved materials crystalline quality, and reduced substrate absorption. The in-plane compressive strain from the GaSb layers in the T2SLs on the InAs was completely balanced by the GaAs-like IF
We report on the control of functionality in long-wavelength light-emitting transistors (LETs) wi... more We report on the control of functionality in long-wavelength light-emitting transistors (LETs) with an InGaAs single quantum-well embedded in N-InP/p-InAlGaAs/N-InAlAs structures by means of the choice of the doping level and dopant in the p-type base layer. As a dual-functional device, the LET works as a heterojunction bipolar transistor (HBT) with a current gain of ~45 when the base doping
A novel type of nanolasers, which combines the advantages of photonic crystal lasers and microdis... more A novel type of nanolasers, which combines the advantages of photonic crystal lasers and microdisk lasers, has been demonstrated based on InAlGaAs/InGaAs quantum wells using pulsed optical pumping at room temperature. It incorporates the properties of small footprint, small mode volume, and submilliwatt threshold, and favors vertical emission. We believe that this type of laser acts as a promising candidate for highly-integrated on-chip nanolasers in applications for signal processing and index sensing.
ABSTRACT Strain-balanced type-II InAs/InAs1-xSbx superlattices with various compositions (x 0.22,... more ABSTRACT Strain-balanced type-II InAs/InAs1-xSbx superlattices with various compositions (x 0.22, 0.23, 0.37) and different layer thicknesses (t(InAs) = 7 nm, t(InAsSb) = 3.3, 2.3, 2.0 nm, respectively) have been grown by metalorganic chemical vapor deposition on GaSb substrates. X-ray diffraction revealed narrow satellite peaks (full-width-half-maximum of < 100 arc sec), indicative of uniform superlattice periodicity and excellent crystallinity, which was also corroborated by cross-sectional transmission electron microscopy observations. Despite relaxation, low-temperature photoluminescence measurements showed peaks at 6.7 mu m and 5.8 mu m, while photoconductance results showed strong spectral response up to 200 K, when the photoresponse onset was 8.6 mu m. (C )2011 American Institute of Physics. [doi:10.1063/1.3625429]
![Research paper thumbnail of [Application of ICP-MS in assessing the pollution of seldom monitored trace elements in city roadside dusts]](https://attachments.academia-assets.com/42113848/thumbnails/1.jpg)
](Guang pu xue yu guang pu fen xi = Guang pu, 2013
Seldom monitored trace element concentrations in road dusts colleted from Shihezi City were studi... more Seldom monitored trace element concentrations in road dusts colleted from Shihezi City were studied. A total of 32 sampling stations were selected. The concentration of 10 seldom monitored trace elements (B, Be, Bi, Co, Ga, Li, Sb, Sn, T1, V) were determined. Their pollution degree and source identification were analyzed by using Geoaccumulation Index, correlation coefficient and principal factor analysis. The results indicated that the mean concentrations of Li, Be, B, V, Co, Ga, Sn, Sb, T1 and Bi were 24. 91, 1.68, 41. 11, 72. 66, 13. 58, 36. 26, 3.64, 3.37, 0. 42 and 0.52 mgkg-1, respectively. The mean concentrations of Li, T1, Co, Be, B, and V were lower than or similar to the soil background values of Xinjiang province. However, the mean concentrations of Ga, Sn, Sb and Bi were higher than the background values of Xijiang province and world soil. The results of Geoaccumulation Index indicated that the pollution degrees of Li, Be, B, V, Co, Ga and T1 were zero, and belonged to t...
TheScientificWorldJournal, 2014
The concentrations, distribution, accumulation, and potential ecological risk of heavy metals (Cr... more The concentrations, distribution, accumulation, and potential ecological risk of heavy metals (Cr, Cu, Zn, Ni, As, Pb, Cd, and Hg) in sediments from the Three Gorges Reservoir (TGR) tributaries were determined and studied. Pb isotopic compositions in sediments were also measured to effectively identify the potential Pb sources. The results showed that the average concentrations of heavy metals in sediment of TGR tributaries were higher than the local background values of soils and sediments in China. The assessment by Geoaccumulation Index indicated that Cu, Ni, and Hg were at the "slightly polluted" level and Cd was ranked as the "moderately polluted" level in tributary sediments of TGR. The assessment by Potential Ecological Risk Index showed that Hg and Cd were the predominant elements in tributary sediments in TGR. The Pb isotopic ratios in sediments varied from 1.171 to 1.202 for (206)Pb/(207)Pb and from 2.459 to 2.482 for (208)Pb/(207)Pb in TGR. All Pb isot...
Dalton Trans., 2013
A systematic theoretical study on the Rh-catalyzed oxidative Heck-coupling of phenol carbamates w... more A systematic theoretical study on the Rh-catalyzed oxidative Heck-coupling of phenol carbamates with alkenes is carried out. Two possible mechanisms (i.e. arene activation-first and alkene activation-first mechanisms) are examined. As to the C-H activation step, four mechanisms including oxidative addition, electrophilic substitution, concerted metallation-deprotonation (CMD), and σ-bond metathesis are evaluated. The calculation results indicate that the arene activation-first mechanism is more favorable for the overall catalytic cycle. This mechanism involves three steps: arene C-H activation at the position ortho to the carbamate directing group affording a six-membered rhodiacycle intermediate, insertion of the alkene double bond into the Rh(III)-aryl bond, and a final β-H elimination step to release the product and re-generate the catalyst. The rate determining step of the overall catalytic cycle is the arene C-H activation step, which is found to proceed through the acetate-assisted CMD mechanism.
J. Am. Chem. Soc., 2013
We developed a photoactivatable firefly luciferase (pfLuc) whose activation can be controlled by ... more We developed a photoactivatable firefly luciferase (pfLuc) whose activation can be controlled by light. A photocaged Lys analogue was site-specifically incorporated into fLuc to replace its key catalytic Lys residue, Lys529, rendering fLuc inactive until light-triggered removal of the caging group. This photoinduced gain of luminescence provides a facile approach for assessing the photolysis efficiency of this valuable photosensitive Lys analogue within the context of its carrier protein in vitro and in living cells. We further took advantage of the spatial and temporal activation feature of pfLuc for intracellular measurement of labile ATP levels without impairment of cellular physiology.
Org. Biomol. Chem., 2014
We described two orthogonal heterocycle syntheses, where an arene bearing both an alkyne and a tr... more We described two orthogonal heterocycle syntheses, where an arene bearing both an alkyne and a triazene functionality underwent two distinct cyclization pathways mediated by different transition metals. Starting from the same substrates, a synthesis of 2H-indazole was accomplished by a Cu(II) salt promoted oxidative cyclization, while 2-substituted indoles could be accessed via a Ag(I) salt mediated N-N bond cleavage. This method represents the first synthesis of indoles from alkynyl triazenes. Computational analysis was performed for both reaction pathways, supporting a Lewis acid role for Cu and a π-acid catalysis for Ag.
Journal of environmental quality
Under anoxic conditions, zerovalent iron (Fe(0)) reduces nitrate to ammonium and magnetite (Fe3O4... more Under anoxic conditions, zerovalent iron (Fe(0)) reduces nitrate to ammonium and magnetite (Fe3O4) is produced at near-neutral pH. Nitrate removal was most rapid at low pH (2-4); however, the formation of a black oxide film at pH 5 to 8 temporarily halted or slowed the reaction unless the system was augmented with Fe(2+), Cu(2+), or Al(3+). Bathing the corroding Fe(0) in a Fe(2+) solution greatly enhanced nitrate reduction at near-neutral pH and coincided with the formation of a black precipitate. X-ray diffractometry and scanning electron microscopy confirmed that both the black precipitate and black oxide coating on the iron surface were magnetite. In this system, ferrous iron was determined to be a partial contributor to nitrate removal, but nitrate reduction was not observed in the absence of Fe(0). Nitrate removal was also enhanced by augmenting the Fe(0)-H2O system with Fe(3+), Cu(2+), or Al(3+) but not Ca(2+), Mg(2+), or Zn(2+). Our research indicates that a magnetite coating...
Chemosphere, 2006
Batch tests were conducted to investigate nitrite reduction in a zerovalent iron (Fe0) system und... more Batch tests were conducted to investigate nitrite reduction in a zerovalent iron (Fe0) system under various conditions. Nitrite at 1.4 mM initial concentration was slowly reduced to nitrogen gas in the first stage (days 1-6), which was mediated by an amorphous, Fe(II)-rich iron oxide coating. The second stage (days 7-14) featured a rapid reduction of nitrite to both ammonia and nitrogen gas and the formation of a more crystalline, magnetite form iron oxide coating. Water reduction by Fe0 occurred concurrently with nitrite reduction from the beginning and contributed significantly to the overall iron corrosion. Nitrite at 14 mM was found to passivate the surface of Fe0 grains with respect to nitrite reduction. Adding aqueous Fe2+ significantly accelerated reduction of nitrite by Fe0 to nitrogen gas with lepidocrocite as the main iron corrosion product. Substantially, though still substoichiometrically, 0.55 mol of Fe2+ were concomitantly consumed per 1.0 mol nitrite reduction, indica...
Organic & Biomolecular Chemistry, 2014
The Journal of Organic Chemistry, 2013
A triple cascade was developed using a simple copper catalyst to trans-selectively access bicycli... more A triple cascade was developed using a simple copper catalyst to trans-selectively access bicyclic isoxazolidines in a one-pot synthesis. This strategy features the in situ generation of nitrones and subsequent trapping by [3 + 2] cycloaddition. In this method, copper serves three catalytic functions: as a Lewis acid for the ene reaction, as an organometallic for aerobic oxidation, and as a Lewis acid for an endo-selective [3 + 2] cycloaddition. The successful merging of aerobic oxidation and Lewis acid catalysis demonstrated efficient cascade synergy.
Chemical Communications, 2013
α,β-Unsaturated ketones and aldehydes have been synthesized from their corresponding silyl enol e... more α,β-Unsaturated ketones and aldehydes have been synthesized from their corresponding silyl enol ethers in a straightforward protocol involving a visible-light promoted organocatalytic, aerobic oxidation reaction. A cheap organic dye was used catalytically in these reactions as the photosensitizer.
Chemical Communications, 2013
An enantioselective organocatalytic process for the one-step synthesis of poly-substituted 1,2,4-... more An enantioselective organocatalytic process for the one-step synthesis of poly-substituted 1,2,4-triazolines is reported. The heterocycle formation is believed to go through a step-wise mechanism of nucleophilic addition of an azlactone to an azodicarboxylate in the presence of an organic base catalyst, followed by a TMSCHN2 mediated heterocyclization. Both theoretical calculations and experimental evidence suggest the pre-organization of the transition state for the chirality determining step via a unique 7-membered intramolecular hydrogen bonding.
Glycoconjugate …, 1998
The activities of three N-acetylglucosaminyltransferases (GnT III, GnT IV and GnT V) were determi... more The activities of three N-acetylglucosaminyltransferases (GnT III, GnT IV and GnT V) were determined in 10 samples of pancreatic carcinoma (PCa) and compared with those in 9 samples of normal pancreatic tissue (NP). It was found that the specific activities of GnT III, GnT IV and GnT V increased in all of the PCa samples. GnT III increased most significantly, up to 22.3 fold of normal, GnT IV was elevated 12.3 fold, while GnT V increased only 2.4 fold. The elevation of GnTs in pancreatic carcinoma was consistent with the increase in the number of antenna and bisecting GlcNAc structures in N-glycans of pancreatic ribonuclease (RNase) as assessed by Con A affinity chromatography. Polycytidylate specific RNase from the serum of PCa patients showed the same structural changes as that found in in N-glycans of the RNase from PCa tissue.
Applied Physics Letters, 2014
ABSTRACT We demonstrate a multi-wavelength distributed feedback (DFB) quantum cascade laser (QCL)... more ABSTRACT We demonstrate a multi-wavelength distributed feedback (DFB) quantum cascade laser (QCL) operating in a lensless external micro-cavity and achieve switchable single-mode emission at three distinct wavelengths selected by the DFB grating, each with a side-mode suppression ratio larger than 30 dB. Discrete wavelength tuning is achieved by modulating the feedback experienced by each mode of the multi-wavelength DFB QCL, resulting from a variation of the external cavity length. This method also provides a post-fabrication control of the lasing modes to correct for fabrication inhomogeneities, in particular, related to the cleaved facets position.
Journal of hazardous materials, Jan 30, 2015
Magnetic imprinted polymers (MIPs) were synthesized by Pickering emulsion polymerization and used... more Magnetic imprinted polymers (MIPs) were synthesized by Pickering emulsion polymerization and used to adsorb erythromycin (ERY) from aqueous solution. The oil-in-water Pickering emulsion was stabilized by chitosan nanoparticles with hydrophobic Fe3O4 nanoparticles as magnetic carrier. The imprinting system was fabricated by radical polymerization with functional and crosslinked monomer in the oil phase. Batches of static and dynamic adsorption experiments were conducted to analyze the adsorption performance on ERY. Isotherm data of MIPs well fitted the Freundlich model (from 15°C to 35°C), which indicated heterogeneous adsorption for ERY. The ERY adsorption capacity of MIPs was about 52.32μmol/g at 15°C. The adsorption kinetics was well described by the pseudo-first-order model, which suggested that physical interactions were primarily responsible for ERY adsorption. The Thomas model used in the fixed-bed adsorption design provided a better fit to the experimental data. Meanwhile, ER...
PloS one, 2014
Spider venom comprises a mixture of compounds with diverse biological activities, which are used ... more Spider venom comprises a mixture of compounds with diverse biological activities, which are used to capture prey and defend against predators. The peptide components bind a broad range of cellular targets with high affinity and selectivity, and appear to have remarkable structural diversity. Although spider venoms have been intensively investigated over the past few decades, venomic strategies to date have generally focused on high-abundance peptides. In addition, the lack of complete spider genomes or representative cDNA libraries has presented significant limitations for researchers interested in molecular diversity and understanding the genetic mechanisms of toxin evolution. In the present study, second-generation sequencing technologies, combined with proteomic analysis, were applied to determine the diverse peptide toxins in venom of the Chinese bird spider Ornithoctonus huwena. In total, 626 toxin precursor sequences were retrieved from transcriptomic data. All toxin precursor...
ONE HUNDRED AND FIVE PATIENTS WITH PRIMARY UNIPOLAR DEPRESSION WERE RANDOMLY DIVIDED INTO THREE G... more ONE HUNDRED AND FIVE PATIENTS WITH PRIMARY UNIPOLAR DEPRESSION WERE RANDOMLY DIVIDED INTO THREE GROUPS: drug group (Seroxat administration), acupuncture group (Seroxat plus acupuncture), and electroacupuncture group (Seroxat plus acupuncture plus electroacupuncture). Patients&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; symptoms were evaluated using a psychometric questionnaire, the Symptom Checklist-90, before intervention and after 2, 4, 6 and 10 weeks of treatment. The individual factor scores and the total score from the Symptom Checklist-90 reduced in all three groups as treatment progressed. In the acupuncture and electroacupuncture groups, the total score and the factor scores for obsessive-compulsive symptoms, depression, and anxiety were significantly lower than those in the drug group. There was no significant difference in the factor scores or total scores between the acupuncture and electroacupuncture groups. Some factor scores in the electroacupuncture group, such as somatization, depression, hostility, and phobic anxiety, were increased at 10 weeks compared with the respective score immediately after the course of electroacupuncture at 6 weeks. Our findings indicate that administration of Seroxat alone or in combination with acupuncture/electroacupuncture can produce a significant effect in patients with primary unipolar depression. Furthermore, acupuncture/electroacupuncture has a rapid onset of therapeutic effect and produces a noticeable improvement in obsessive-compulsive, depressive and anxiety symptoms.
We propose and demonstrate strain-balanced InAs/GaSb type-II superlattices (T2SLs) grown on InAs ... more We propose and demonstrate strain-balanced InAs/GaSb type-II superlattices (T2SLs) grown on InAs substrates employing GaAs-like interfacial (IF) layers by metalorganic chemical vapor deposition (MOCVD) for effective strain management, simplified growth scheme, improved materials crystalline quality, and reduced substrate absorption. The in-plane compressive strain from the GaSb layers in the T2SLs on the InAs was completely balanced by the GaAs-like IF
We report on the control of functionality in long-wavelength light-emitting transistors (LETs) wi... more We report on the control of functionality in long-wavelength light-emitting transistors (LETs) with an InGaAs single quantum-well embedded in N-InP/p-InAlGaAs/N-InAlAs structures by means of the choice of the doping level and dopant in the p-type base layer. As a dual-functional device, the LET works as a heterojunction bipolar transistor (HBT) with a current gain of ~45 when the base doping
A novel type of nanolasers, which combines the advantages of photonic crystal lasers and microdis... more A novel type of nanolasers, which combines the advantages of photonic crystal lasers and microdisk lasers, has been demonstrated based on InAlGaAs/InGaAs quantum wells using pulsed optical pumping at room temperature. It incorporates the properties of small footprint, small mode volume, and submilliwatt threshold, and favors vertical emission. We believe that this type of laser acts as a promising candidate for highly-integrated on-chip nanolasers in applications for signal processing and index sensing.
ABSTRACT Strain-balanced type-II InAs/InAs1-xSbx superlattices with various compositions (x 0.22,... more ABSTRACT Strain-balanced type-II InAs/InAs1-xSbx superlattices with various compositions (x 0.22, 0.23, 0.37) and different layer thicknesses (t(InAs) = 7 nm, t(InAsSb) = 3.3, 2.3, 2.0 nm, respectively) have been grown by metalorganic chemical vapor deposition on GaSb substrates. X-ray diffraction revealed narrow satellite peaks (full-width-half-maximum of < 100 arc sec), indicative of uniform superlattice periodicity and excellent crystallinity, which was also corroborated by cross-sectional transmission electron microscopy observations. Despite relaxation, low-temperature photoluminescence measurements showed peaks at 6.7 mu m and 5.8 mu m, while photoconductance results showed strong spectral response up to 200 K, when the photoresponse onset was 8.6 mu m. (C )2011 American Institute of Physics. [doi:10.1063/1.3625429]
Guang pu xue yu guang pu fen xi = Guang pu, 2013
Seldom monitored trace element concentrations in road dusts colleted from Shihezi City were studi... more Seldom monitored trace element concentrations in road dusts colleted from Shihezi City were studied. A total of 32 sampling stations were selected. The concentration of 10 seldom monitored trace elements (B, Be, Bi, Co, Ga, Li, Sb, Sn, T1, V) were determined. Their pollution degree and source identification were analyzed by using Geoaccumulation Index, correlation coefficient and principal factor analysis. The results indicated that the mean concentrations of Li, Be, B, V, Co, Ga, Sn, Sb, T1 and Bi were 24. 91, 1.68, 41. 11, 72. 66, 13. 58, 36. 26, 3.64, 3.37, 0. 42 and 0.52 mgkg-1, respectively. The mean concentrations of Li, T1, Co, Be, B, and V were lower than or similar to the soil background values of Xinjiang province. However, the mean concentrations of Ga, Sn, Sb and Bi were higher than the background values of Xijiang province and world soil. The results of Geoaccumulation Index indicated that the pollution degrees of Li, Be, B, V, Co, Ga and T1 were zero, and belonged to t...
TheScientificWorldJournal, 2014
The concentrations, distribution, accumulation, and potential ecological risk of heavy metals (Cr... more The concentrations, distribution, accumulation, and potential ecological risk of heavy metals (Cr, Cu, Zn, Ni, As, Pb, Cd, and Hg) in sediments from the Three Gorges Reservoir (TGR) tributaries were determined and studied. Pb isotopic compositions in sediments were also measured to effectively identify the potential Pb sources. The results showed that the average concentrations of heavy metals in sediment of TGR tributaries were higher than the local background values of soils and sediments in China. The assessment by Geoaccumulation Index indicated that Cu, Ni, and Hg were at the "slightly polluted" level and Cd was ranked as the "moderately polluted" level in tributary sediments of TGR. The assessment by Potential Ecological Risk Index showed that Hg and Cd were the predominant elements in tributary sediments in TGR. The Pb isotopic ratios in sediments varied from 1.171 to 1.202 for (206)Pb/(207)Pb and from 2.459 to 2.482 for (208)Pb/(207)Pb in TGR. All Pb isot...
Dalton Trans., 2013
A systematic theoretical study on the Rh-catalyzed oxidative Heck-coupling of phenol carbamates w... more A systematic theoretical study on the Rh-catalyzed oxidative Heck-coupling of phenol carbamates with alkenes is carried out. Two possible mechanisms (i.e. arene activation-first and alkene activation-first mechanisms) are examined. As to the C-H activation step, four mechanisms including oxidative addition, electrophilic substitution, concerted metallation-deprotonation (CMD), and σ-bond metathesis are evaluated. The calculation results indicate that the arene activation-first mechanism is more favorable for the overall catalytic cycle. This mechanism involves three steps: arene C-H activation at the position ortho to the carbamate directing group affording a six-membered rhodiacycle intermediate, insertion of the alkene double bond into the Rh(III)-aryl bond, and a final β-H elimination step to release the product and re-generate the catalyst. The rate determining step of the overall catalytic cycle is the arene C-H activation step, which is found to proceed through the acetate-assisted CMD mechanism.
J. Am. Chem. Soc., 2013
We developed a photoactivatable firefly luciferase (pfLuc) whose activation can be controlled by ... more We developed a photoactivatable firefly luciferase (pfLuc) whose activation can be controlled by light. A photocaged Lys analogue was site-specifically incorporated into fLuc to replace its key catalytic Lys residue, Lys529, rendering fLuc inactive until light-triggered removal of the caging group. This photoinduced gain of luminescence provides a facile approach for assessing the photolysis efficiency of this valuable photosensitive Lys analogue within the context of its carrier protein in vitro and in living cells. We further took advantage of the spatial and temporal activation feature of pfLuc for intracellular measurement of labile ATP levels without impairment of cellular physiology.
Org. Biomol. Chem., 2014
We described two orthogonal heterocycle syntheses, where an arene bearing both an alkyne and a tr... more We described two orthogonal heterocycle syntheses, where an arene bearing both an alkyne and a triazene functionality underwent two distinct cyclization pathways mediated by different transition metals. Starting from the same substrates, a synthesis of 2H-indazole was accomplished by a Cu(II) salt promoted oxidative cyclization, while 2-substituted indoles could be accessed via a Ag(I) salt mediated N-N bond cleavage. This method represents the first synthesis of indoles from alkynyl triazenes. Computational analysis was performed for both reaction pathways, supporting a Lewis acid role for Cu and a π-acid catalysis for Ag.
Journal of environmental quality
Under anoxic conditions, zerovalent iron (Fe(0)) reduces nitrate to ammonium and magnetite (Fe3O4... more Under anoxic conditions, zerovalent iron (Fe(0)) reduces nitrate to ammonium and magnetite (Fe3O4) is produced at near-neutral pH. Nitrate removal was most rapid at low pH (2-4); however, the formation of a black oxide film at pH 5 to 8 temporarily halted or slowed the reaction unless the system was augmented with Fe(2+), Cu(2+), or Al(3+). Bathing the corroding Fe(0) in a Fe(2+) solution greatly enhanced nitrate reduction at near-neutral pH and coincided with the formation of a black precipitate. X-ray diffractometry and scanning electron microscopy confirmed that both the black precipitate and black oxide coating on the iron surface were magnetite. In this system, ferrous iron was determined to be a partial contributor to nitrate removal, but nitrate reduction was not observed in the absence of Fe(0). Nitrate removal was also enhanced by augmenting the Fe(0)-H2O system with Fe(3+), Cu(2+), or Al(3+) but not Ca(2+), Mg(2+), or Zn(2+). Our research indicates that a magnetite coating...
Chemosphere, 2006
Batch tests were conducted to investigate nitrite reduction in a zerovalent iron (Fe0) system und... more Batch tests were conducted to investigate nitrite reduction in a zerovalent iron (Fe0) system under various conditions. Nitrite at 1.4 mM initial concentration was slowly reduced to nitrogen gas in the first stage (days 1-6), which was mediated by an amorphous, Fe(II)-rich iron oxide coating. The second stage (days 7-14) featured a rapid reduction of nitrite to both ammonia and nitrogen gas and the formation of a more crystalline, magnetite form iron oxide coating. Water reduction by Fe0 occurred concurrently with nitrite reduction from the beginning and contributed significantly to the overall iron corrosion. Nitrite at 14 mM was found to passivate the surface of Fe0 grains with respect to nitrite reduction. Adding aqueous Fe2+ significantly accelerated reduction of nitrite by Fe0 to nitrogen gas with lepidocrocite as the main iron corrosion product. Substantially, though still substoichiometrically, 0.55 mol of Fe2+ were concomitantly consumed per 1.0 mol nitrite reduction, indica...
Organic & Biomolecular Chemistry, 2014
The Journal of Organic Chemistry, 2013
A triple cascade was developed using a simple copper catalyst to trans-selectively access bicycli... more A triple cascade was developed using a simple copper catalyst to trans-selectively access bicyclic isoxazolidines in a one-pot synthesis. This strategy features the in situ generation of nitrones and subsequent trapping by [3 + 2] cycloaddition. In this method, copper serves three catalytic functions: as a Lewis acid for the ene reaction, as an organometallic for aerobic oxidation, and as a Lewis acid for an endo-selective [3 + 2] cycloaddition. The successful merging of aerobic oxidation and Lewis acid catalysis demonstrated efficient cascade synergy.
Chemical Communications, 2013
α,β-Unsaturated ketones and aldehydes have been synthesized from their corresponding silyl enol e... more α,β-Unsaturated ketones and aldehydes have been synthesized from their corresponding silyl enol ethers in a straightforward protocol involving a visible-light promoted organocatalytic, aerobic oxidation reaction. A cheap organic dye was used catalytically in these reactions as the photosensitizer.
Chemical Communications, 2013
An enantioselective organocatalytic process for the one-step synthesis of poly-substituted 1,2,4-... more An enantioselective organocatalytic process for the one-step synthesis of poly-substituted 1,2,4-triazolines is reported. The heterocycle formation is believed to go through a step-wise mechanism of nucleophilic addition of an azlactone to an azodicarboxylate in the presence of an organic base catalyst, followed by a TMSCHN2 mediated heterocyclization. Both theoretical calculations and experimental evidence suggest the pre-organization of the transition state for the chirality determining step via a unique 7-membered intramolecular hydrogen bonding.
Glycoconjugate …, 1998
The activities of three N-acetylglucosaminyltransferases (GnT III, GnT IV and GnT V) were determi... more The activities of three N-acetylglucosaminyltransferases (GnT III, GnT IV and GnT V) were determined in 10 samples of pancreatic carcinoma (PCa) and compared with those in 9 samples of normal pancreatic tissue (NP). It was found that the specific activities of GnT III, GnT IV and GnT V increased in all of the PCa samples. GnT III increased most significantly, up to 22.3 fold of normal, GnT IV was elevated 12.3 fold, while GnT V increased only 2.4 fold. The elevation of GnTs in pancreatic carcinoma was consistent with the increase in the number of antenna and bisecting GlcNAc structures in N-glycans of pancreatic ribonuclease (RNase) as assessed by Con A affinity chromatography. Polycytidylate specific RNase from the serum of PCa patients showed the same structural changes as that found in in N-glycans of the RNase from PCa tissue.
Applied Physics Letters, 2014
ABSTRACT We demonstrate a multi-wavelength distributed feedback (DFB) quantum cascade laser (QCL)... more ABSTRACT We demonstrate a multi-wavelength distributed feedback (DFB) quantum cascade laser (QCL) operating in a lensless external micro-cavity and achieve switchable single-mode emission at three distinct wavelengths selected by the DFB grating, each with a side-mode suppression ratio larger than 30 dB. Discrete wavelength tuning is achieved by modulating the feedback experienced by each mode of the multi-wavelength DFB QCL, resulting from a variation of the external cavity length. This method also provides a post-fabrication control of the lasing modes to correct for fabrication inhomogeneities, in particular, related to the cleaved facets position.