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Yong Qin

Publications and source records attributed to Yong Qin.

At least 19 recordsLinked to original sources
PubMed2006

Some characteristics of the distribution of heavy metals in urban topsoil of Xuzhou, China.

An assessment is presented of distribution characteristics of heavy metals in the urban topsoil from the city of Xuzhou. The concentrations of Ag, Al, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, Hg, Li, Mn, Mo, Ni, Pb, Pd, Pt, Sb, Sc, Se, Sn, V and Zn have been determined from 21 soil samples. Examination of lognormal distribution plots indicates that the diagrams of Al, Be, Fe, Ga, Li, and V are almost linear suggesting that these metals are almost unaffected by anthropogenic activities while the plots for As, Cd, Cu, Pb, Pd, Pt, Se, Zn and others are not linear probably due to anthropogenic activities from which these metals are delivered to the soils. Al is used for mineralogical normalization of these data. An evaluation of background values for topsoil is also carried out by means of lognormal distribution plots. The results show our background values obtained from the lognormal distribution plots are comparable to those values of uncontaminated soils of Xuzhou obtained by previous work except for Cd and Hg. At present, no explanation for the exceptions Cd and Hg can be given.

China↗
PubMed2006

Synthesis of chiral 3-substituted hexahydropyrroloindoline via intermolecular cyclopropanation.

[Structure: see text] A new and efficient synthetic route to chiral 3-substituted hexahydropyrroloindoline 18 possessing absolute configurations in accordance with indole alkaloids has been developed from readily available L-tryptophan. The key step relies on the one-pot cascade reaction of oxazolidinone 17 with diazoester, which proceeds through intermolecular cyclopropanation, ring opening, and cyclization.

Cyclopropanes↗
PubMed2006

Molecular dynamics simulation of nanodroplet spreading enhanced by linear surfactants.

We utilize molecular dynamics simulations to probe the surfactant-mediated spreading of a Lennard-Jones liquid droplet on a solid surface. The surfactants are linear hexamers that are insoluble in the liquid and reduce the surface tension of the liquid-vapor interface. We study how the interaction of the surfactant hexamers with the solid substrate influences spreading, as well as the dependence of spreading on surfactant concentration. We find that the spreading speed is strongly influenced by the attraction of the hydrophobic surfactant tail to the solid surface. When this attraction is sufficiently strong, surfactant molecules partition to the liquid-solid interface and facilitate spreading. This partitioning can lead to an inhomogeneous distribution of surfactant over the liquid-vapor interface, which could drive the Marangoni convection. We also observe that the surfactant molecules can assemble into micelles on the solid surface. The repulsion between micelles at the liquid-solid interface can lead to break-off and migration of the micelles from the liquid-solid to the gas-solid interface and spreading is facilitated in this way. Our model system contains features that are believed to underlie superspreading in experimental studies of droplet spreading.

Journal Article↗
PubMed2006

Leaching characteristics of arsenic and heavy metals in urban roadside soils using a simple bioavailability extraction test.

Regular ingestion of soils could pose a potential health threat due to long-term toxic element exposure. In order to estimate the human bioavailability quotients for As and heavy metals, 12 urban roadside soil samples were collected and analyzed for As, Pb, Cu, Zn, Ni, Co, and Cr using Simple Bioavailability Extraction Test (SBET). The quantities of As, Pb, Cu, Zn, Ni, Co, and Cr leached from soils within the simulated human stomach for 1 h indicated, on average, 27.3, 71.7, 40.4, 59.3, 17.7, 27.2 and 5.6% bioavailability, respectively. Significant positive correlations were observed between the amounts leached using SBET and the total amounts dissolved with HNO(3)-HCl-HF acid mixtures. Stepwise multiple regression analysis indicated that the amounts leached with SBET for As, Pb, Zn, Ni, and Co were not related to any of the physic-chemical parameters measured (i.e., soil texture, pH, total organic matter). These results may be valuable for providing input data for risk assessment at sites subject to anthropogenic soil contamination.

Arsenic↗
PubMed2006

Determination of kinetic and equilibrium parameters of the batch adsorption of Ni(II) from aqueous solutions by Na-mordenite.

The potential to remove nickel(II) ions from aqueous solutions using Na-mordenite, a common zeolite mineral, was thoroughly investigated. The effects of relevant parameters solution pH, adsorbent dose, ionic strength, and temperature on nickel(II) adsorption capacity were examined. The sorption data followed the Langmuir, Freundlich, Langmuir-Freundlich and Dubinin-Radushkevich (D-R) isotherms. The maximum sorption capacity was found to be 5.324 mg/g at pH 6, initial concentration of 40 mg/L and temperature of 20 degrees C. Thermodynamic parameters, viz. changes in standard free energy (DeltaG degrees ), enthalpy (DeltaH degrees ) and entropy (DeltaS degrees ) have also been evaluated and the results show that the sorption process was spontaneous and endothermic in nature. Dynamics of the sorption process were studied and the values of rate constant of adsorption, rate constant of intraparticle diffusion were calculated. The activation energy (E(a)) was found to be 12.465 kJ/mol in the present study, indicating a chemical sorption process involving weak interactions between sorbent and sorbate. The sorption capacity increased with the increase of solution pH and the decrease of ionic strength and adsorbent dose. The nickel(II) ions sorption by the Na-mordenite is not completely attributable to ion exchange. Compared to the other adsorbents, the nickel(II) ions show a lower affinity towards the clay mineral adsorbents.

Aluminum Silicates↗
PubMed2006

Solvophobic solvation at large and intermediate length scales: Size, shape, and solvent effects.

We report the results of molecular-dynamics simulations of solvophobic nanoparticles in n -decane solvent. We observe that solvent ordering in the interparticle gap and solvation forces depend on the particle size and shape. Analogous to hydrophobic hydration, we observe dewetting of the interparticle region when the nanoparticle separation becomes smaller than a critical value of delta(c). We observe that delta(c) exhibits a nonmonotonic dependence on nanoparticle size, in contrast to what is expected from studies of water. While studies of hydrophobic hydration indicate that two solute length scales govern hydrophobic interactions, our studies indicate that a third length scale can be important in the more general phenomenon of solvophobic solvation.

Journal Article↗
PubMed2006

Removal of Ni(II), Zn(II) and Cr(VI) from aqueous solution by Alternanthera philoxeroides biomass.

Alternanthera philoxeroides biomass, a type of freshwater macrophyte, was used for the sorptive removal of Ni(II), Zn(II) and Cr(VI) from aqueous solutions. Variables of the batch experiments include solution pH, contact time, particle size and temperature. The biosorption capacities are significantly affected by solution pH. Higher pH favors higher Ni(II), Zn(II) removal, whereas higher uptake of Cr(VI) is observed as the pH is decreased. A two-stage kinetic behavior is observed in the biosorption of Ni(II), Zn(II) and Cr(VI): very rapid initial biosorption in a few minutes, followed by a long period of a slower uptake. It is noted that an increase in temperature results in a higher Ni(II), Zn(II) and Cr(VI) loading per unit weight of the sorbent. Decreasing the particle sizes of the Alternanthera philoxeroides biomass leads to an increase in the Ni(II), Zn(II) and Cr(VI) uptake per unit weight of the sorbent. All isothermal data are fairly well fitted with Langmuir equations. The thermodynamic parameter, DeltaG degrees, were calculated. The negative DeltaG degrees values of Cr(VI), Ni(II) and Zn(II) at various temperatures confirm the adsorption processes are spontaneous.

Adsorption↗
PubMed2006

A novel butenoate derivative from Aspergillus niger.

A novel butenoate derivative, methyl (Z)-4-{[(Z)-1-(hydroxymethyl)-2-phenyl-1-ethenyl] amino}-4-oxo-2-butenoate (1), was isolated from the fermentation broth of an Aspergillus niger strain Ta1. The structure (1) was elucidated by spectral analysis. Bioassays showed that compound 1 had a weak antioxidant activity.

Antioxidants↗
PubMed2006

Biomimetic approach to perophoramidine and communesin via an intramolecular cyclopropanation reaction.

[reaction: see text] Starting from tryptamine 4 and isatin 5, a biomimetic approach to the pentacyclic substructure 1 of perophoramidine and communesin was developed. The key steps were to create a stable three/six bicyclic system 2 on the 2,3-double bond of an indole derivative 3 by an intramolecular cyclopropanation, followed by ring opening of the resulting cyclopropane ring with the in situ generated amine group of an aniline.

Cyclopropanes↗
PubMed2006

Aerobic biodegradation of alkylphenol ethoxylates.

Primary aerobic biodegradation of alkylphenol ethoxylates (APEOs) was studied using a new simple and fast porphyrin method, which did not require the extraction step. Extent of primary biodegradation of a nonylphenol ethoxylates (NP-10) was excess of 92% after 1.5 days, and reached 99% after 2 days, which was similar to the results obtained using modified CTAS (thiocyanate active substances) method. Degradation of benzene ring of NP-10 was studied using UV-absorbance at 277 nm in chloroform. Results showed that only little of benzene ring was degraded.

Bacteria, Aerobic↗
PubMed2006

Spacer length and attaching position-dependent binding of synthesized protoberberine dimers to double-stranded DNA.

Six jatrorrhizine homodimers and berberine-jatrorrhizine heterodimers have been synthesized in moderate to good yields from the reaction of jatrorrhizine with alpha,omega-dibromoalkanes and 9-O-(omega-bromoalkyl)berberines, respectively. Their binding activities toward calf thymus (CT) DNA and three double-stranded oligodeoxynucleotides, d(AAGAATTCTT)(2), d(TAAGAATTCTTA)(2), and d(TTAAGAATTCTTAA)(2), were investigated by means of spectrofluorimetric and spectrophotometric titrations. The results indicate that these dimers exhibit enhanced DNA-binding affinities due to the cooperative interaction of the two protoberberine subunits. A comparative study of the DNA-binding behaviors of berberine homodimers, jatrorrhizine homodimers, and berberine-jatrorrhizine heterodimers suggests that spacer length and attaching position are of great importance in modulating their DNA-binding affinities.

Berberine↗
PubMed2006

Highly diastereoselective enolate addition of O-protected alpha-hydroxyacetate to (S(R))-tert-butanesulfinylimines: synthesis of taxol side chain.

The taxol side chain (S(R),2R,3S)-N-tert-butanesulfinyl-O-Boc-3-phenylisoserine benzyl ester 4c was synthesized through a lithium enolate addition of O-Boc-alpha-hydroxyacetate benzyl ester 5c to benzylidene (S(R))-tert-butanesulfinamide 6a in excellent yield and diastereoselectivity. By similar approach, a series of enantiopure 3-substituted isoserine benzyl esters 4 useful for the semi-syntheses of taxol derivatives were also prepared in high to excellent yields and diastereoselectivities. The diastereoselective addition mechanism was discussed on the basis of the experimental observation.

Benzene Derivatives↗
PubMed2006

Solvation forces between colloidal nanoparticles: directed alignment.

We study the solvation forces between colloidal nanoparticles in Lennard-Jones liquids using molecular-dynamics simulations. We find that due to the interplay between solvent ordering and surface structure, the solvation forces between two nanoparticles can vary between attraction and repulsion as the particles are rotated relative to one another at a fixed separation. These solvent-mediated forces tend to align the nanoparticles so that they rotate to approach one another in a solution via preferred pathways. This directed alignment could play a role in the assembly of macromolecules and nanoparticles in solution.

Journal Article↗
PubMed2006

Selective diethylzinc reduction of imines in the presence of ketones catalyzed by Ni(acac)2.

A selective reduction method of an electronically deficient imine in the presence of ketone was developed by employing Et(2)Zn and 5 mol % of Ni(acac)(2). The method was applied in the reduction of S(S)-tert-butanesulfinyl ketimines 1 to afford amines 2 in 23-92% yields and 73:27 to 98:2 diastereoselectivities. A plausible mechanism was proposed on the basis of an NMR study.

Journal Article↗
PubMed2006

[Managements of masked mastoiditis].

OBJECTIVE: To appreciate clinically of masked mastoiditis to explored how to reduce the incidence and associated morbidity of otogenic complications. METHODS: Between January 1998 and February 2005, 11 cases of masked mastoiditis were collected retrospectively. Their clinical presentation, results of investigations, and response to treatment were reviewed. RESULTS: Of 11 cases, there were 8 cases with hearing impairment, 5 cases with otalgia, 4 cases with facial nerve palsy, one patient with postauricular subperiosteal abscess, one case with meningitis, and one with thrombosis of the lateral sinus. Computed tomography (CT) scan revealed blurring (haziness) of the mastoid air-cells. After admission, intravenous antibiotics were prescribed and antro-mastoidectomy or mastoidectomy was performed for eradication of infection source. The predominant finding at mastoidectomy was granulation tissue filling the mastoid cavity and antrum. A varying amount of pus and osteitis was found in the 5 cases. The granulations into the antrum were severe, obstructing the drainage into the attic and the middle ear. The mastoid tip cells were filled with granulation tissue which spared the antrum. The patients recovered excellently postoperative, without facial palsy, vertigo or other complications. CONCLUSIONS: To be a contemporary otologist, such severe complications of otologic diseases should not be overlooked. Appropriate intravenous antibiotics and adequate surgeries, as soon as possible, were recommended. Advanced CT scans of the temporal bone were necessary. Failure to identify associated concomitant pathology might result in treatment failure or persistent neurological deficit.

Adult↗
PubMed2006

[Efficacy of HSV-tk/GCV system on human laryngeal squamous cell cancer in vitro].

OBJECTIVE: Efficacy of HSV-tk/GCV system antitumor effects was assessed on human laryngeal cancer cell line Hep-2 in vitro. To assess the HSV-tk/CGV system whether has an antitumour effect on human laryngeal squamous cell cancer Hep-2 in vitro. The mechanisms of cytotoxity were also assessed. METHODS: Hep-2 cells were transfected with HSV-tk gene by lipofection. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect the HSV-tk gene expression. MTT was utilized to test for the cytotoxicity of this system. The cell-circle arrest and apoptosis were analyzed by flowcytometry assay. RESULTS: HSV-tk gene transfected cells demonstrated obvious cytoreductivity followed by ganciclovir (GCV) administration and this cytoreductivity showed partial GCV dose-independent. HSV-tk gene transfected cells demonstrated obvious s-phase arrest, no apoptosis and necrosis occurred. CONCLUSIONS: The HSV-tk/GCV system can inhabit the growth of Hep-2 cells effectively. S-phase arrest perhaps is the main reason that leads to the cell inhibition in our study. HSV-tk/GCV system has potential antitumor effects for the future clinical practice.

Carcinoma, Squamous Cell↗