Biomedical subjects

Xiao-Yan Tang

Publications and source records attributed to Xiao-Yan Tang.

9 recordsLinked to original sources

PubMed2006

Toward rational construction of gold, gold-silver, and gold-mercury string complexes: syntheses, structures, and properties of [Au(Tab)2]2L2 (L = I and PF6), {[(Tab)2M][Au(CN)2]}2 (M = Au and Ag), and {[Hg(Tab)2][Au(CN)2]2} [Tab = 4-(trimethylammonio)benzenethiolate].

The reaction of AuI with 2 equiv of TabHPF6 [TabH = 4-(trimethylammonio)benzenethiol] in the presence of excess Et3N in dimethylformamide (DMF)/MeOH afforded a binuclear gold(I) complex [Au(Tab)2]2I2.2H2O (1). Anion exchange of 1 with NH4PF6 in DMF gave rise to the more soluble complex [Au(Tab)2]2(PF6)2 (2). Treatment of 2 with K[Au(CN)2] produced a tetranuclear gold(I) complex {[(Tab)2Au][Au(CN)2]}2 (3). Analogous reactions of two known mononuclear complexes [Ag(Tab)2](PF6) (4) and [Hg(Tab)2](PF6)2 (5) with 1 or 2 equiv of K[Au(CN)2] generated one Ag2Au2 complex {[(Tab)2Ag][Au(CN)2]}2 (6) and one Au/Hg complex {[Hg(Tab)2][Au(CN)2]2} (7), respectively. Compounds 1-3, 6, and 7 were fully characterized by elemental analysis, IR spectra, UV-vis spectra, 1H NMR, and single-crystal X-ray crystallography. 1 and 2 have a similar [Au(Tab)2]2(2+) dimeric structure in which the two [Au(Tab)2]+ cations are connected via one Au-Au aurophilic interaction. In the structure of 3 or 6, each of the two pairs of [M(Tab)2]+ cation and [Au(CN)2]- anion is held together via ionic interactions to form a {[(Tab)2M][Au(CN)2]} species (M = Au, 3; Ag, 6). Two such species are further connected by one Au-Au aurophilic bonding interaction to form an uncommon Au(4) or Ag2Au2 linear string structure with three ligand-unsupported metal-metal bonds. For 7, the [Hg(Tab)2]2+ dication and the [Au(CN)2]2(2-) dianion are interconnected by the secondary Hg...N(CN) interactions to form a 1D chain structure. The thermal and luminescent properties of 1-3, 6, and 7 in solid state were also investigated.

Journal Article↗

PubMed2006

Assembly of a new family of mercury(II) zwitterionic thiolate complexes from a preformed compound [Hg(Tab)2](PF6)2 [Tab = 4-(trimethylammonio)benzenethiolate].

Reactions of Hg(OAc)2 with 2 equiv of TabHPF6 [TabH = 4-(trimethylammonio)benzenethiol] in MeCN/MeOH afforded a mononuclear linear complex [Hg(Tab)2](PF6)2 (1). By using 1 as a precursor, a new family of mercury(II) zwitterionic thiolate complexes, [Hg2(Tab)6](PF6)4.2MeCN (2.2MeCN), [Hg(Tab)2(SCN)](PF6) (3), [Hg(Tab)2(SCN)2] (4), [Hg(Tab)I2] (5), {[Hg(Tab)2]4[HgI2][Hg2I6]}(PF6)2(NO3)4 (6), [Hg(Tab)2][HgI4] (7), [Hg(Tab)2][HgCl2(SCN)2] (8), [Tab-Tab]2[Hg3Cl10] (9), and [Hg2(Tab)6]3(PF6)Cl11 (10), were prepared and characterized by elemental analysis, IR spectra, UV-vis spectra, 1H NMR, and single-crystal X-ray crystallography. The [Hg2(Tab)6]4+ tetracation of 2 or 10 contains an asymmetrical Hg2S2 rhomb with an inversion center lying on the midpoint of the Hg...Hg line. The Hg atom of the [Hg(Tab)2]2+ dication of 3 is coordinated to one SCN-, forming a rare T-shaped coordination geometry, while in 4, the Hg atom of [Hg(Tab)2]2+ is coordinated to two SCN-, forming a seesaw-shaped coordination geometry. Through weak secondary Hg...S coordinations, each cation in 3 is further linked to afford a one-dimensional zigzag chain. The trigonal [Hg(Tab)I2] molecules in 5 are held together by weak secondary Hg...I and Hg...S interactions, forming a one-dimensional chain structure. In 6, the four [Hg(Tab)2]2+ dications, one HgI2 molecule, one [Hg2I6]2- dianion, one PF6-, and four NO3- anions are interconnected by complicated secondary Hg...I and Hg...O interactions, forming a scolopendra-like chain structure. The secondary Hg...I interactions, [Hg(Tab)2]2+ and [HgI4]2- in 7, are combined to generate a one-dimensional chain structure, while [Hg(Tab)2]2+ and [HgCl2(SCN)2]2- in 8 are interconnected by secondary Hg...N interactions to form a one-dimensional zigzag chain structure. Compound 9 consists of two [Tab-Tab]2+ dications and one [Hg3Cl10]4- tetraanion. The facile approach to the construction of 2-8 and 10 from 1 may be applicable to the mimicking of a coordination sphere of the Hg sites of metallothioneins.

Crystallography, X-Ray↗

PubMed2006

Reduction of precursors of chlorination by-products in drinking water using fluidized-bed biofilm reactor at low temperature.

OBJECTIVE: To investigate the reduction of chlorination by-products (CBPs) precursors using the fluidized-bed biofilm reactor (FBBR). METHODS: Reduction of total organic carbon (TOC), ultraviolet absorbance (UV254), trihalomethane (THM) formation potential (THMFP), haloacetic acid (HAA) formation potential (HAAFP), and ammonia in FBBR were evaluated in detail. Results The reduction of TOC or UV254 was low, on average 12.6% and 4.7%, respectively, while the reduction of THMFP and HAAFP was significant. The reduction of ammonia was 30%-40% even below 3 degrees C, however, it could quickly rise to over 50% above 3degrees C. Conclusions The FBBR effectively reduces CBPs and ammonia in drinking water even at low temperature and seems to be a very promising and competitive drinking water reactor for polluted surface source waters, especially in China.

Biofilms↗

PubMed2005

Seasonal pollution characteristics of organic compounds in atmospheric fine particles in Beijing.

Beijing is a rapidly developing city with severe and unique air pollution problems. Organic matter is the most abundant fraction in fine particles in Beijing, occupying 30-50% of the total mass, indicating its key role in air pollution control. However, detailed chemical characterization of particulate organic matter in Beijing has never been reported. In this study, fine particles in the urban atmosphere in Beijing were investigated for its organic components by GC/MS technique. Over 100 individual organic compounds were identified and quantified in 25 PM2.5 samples from the summer, autumn and winter of 2002-2003. Alkanes, fatty acids, dicarboxylic acids, polycyclic aromatic hydrocarbons and some important tracer compounds (hopanes, levoglucosan and steroids) were the major constituents with the sum of their concentrations of 502, 1471 and 1403 ng m(-3) in summer, autumn and winter, respectively. Different organic compounds presented apparently different seasonal characteristics, reflecting their different dominant emission sources, such as coal combustion, biomass burning and cooking emission. The abundance and origin of these organic compounds are discussed to reveal seasonal air pollution characteristics of Beijing.

Air Pollutants↗

PubMed2005

Interactions among periodic waves and solitary waves of the (N + 1)-dimensional sine-Gordon field.

Exact solutions of the (n + 1)-dimensional sine-Gordon field equation are studied with help of those of the cubic nonlinear Klein-Gordon fields. The mapping relations among the sine-Gordon field equation and the cubic nonlinear Klein-Gordon fields are pure algebraic. By solving the cubic nonlinear Klein-Gordon equations, many new types of exact explicit solutions such as the periodic-periodic interaction waves, periodic-kink interaction waves, periodic perturbed "snake" shape solitary waves, etc., are displayed both analytically and graphically.

Journal Article↗

PubMed2005

Biological pretreatment of Yellow River water.

Bio-ceramic filter(BF) and moving-bed biofilm reactor (MBBR) were used for biological pretreatment of Yellow River water in this study. The BF only had slight advantage over MBBR for TOC and ammonia removal. However, like UV254, the average removal rate of THMFP in the BF was much higher than that in the MBBR. UV254 removal did not show obvious correlation with trihalomethane formation potential (THMFP) removal. Hexachlorocyclohexane could be effectively removed in both BF and MBBR. As for diatom and cyanobateria removal the MBBR had better performance than the BF, which was contrary to the average chlorophyll-a ( Chl-a) removal rate. The proposal was made in this study that biological flocculation and sedimentation of sloughed biofilm should play a more important role on algae removal in the MBBR than in the BF. The BF and MBBR could effectively remove microcystins. Moreover, MBBR could be a promising technology for biological pretreatment.

Ammonia↗

PubMed2005

[Mass size distribution of Beijing particulate matters and its inorganic water-soluble ions in winter and summer].

To understand one of the important characteristics of Beijing particulate matter pollution, the mass size distribution of particulate matters and its water-soluble ions, the particle samples were collected by a MOUDI cascade impactor in Beijing during July 2001, March 2002, July 2002 and January 2003 and every sampling period lasted a week. By analysis, the results indicate that there is "two modes" in the diameter range of the fine particle, one called "condensation mode" and another called "droplet mode", and the reasons of the peak of the accumulation mode appearing in the diameter range of 1 - 1. 8 microm was discussed in this paper. And there was a relatively strong correlation between PM1.8 and PM10 (R2 > 80%), the same to PM(1.8-10) (PM10 minus PM1.8); the ratio of PM1.8s/PM10 varietied between 40% and 60% during the sampling periods; as a result, the mass concentration of PM10 can be decreased by decreasing the concentration of coarse particles; sulfate, nitrate and ammonium are the main component of the inorganic water-soluble ions and the percentage of these three ions in PM1.8 was above 70% when the concentration of fine particle was more than 70 microg x m(-3) and they are the main reason increasing particle concentration.

Air Pollutants↗

PubMed2002

Localized excitations in (2+1)-dimensional systems.

By means of a special variable separation approach, a common formula with some arbitrary functions has been obtained for some suitable physical quantities of various (2+1)-dimensional models such as the Davey-Stewartson (DS) model, the Nizhnik-Novikov-Veselov (NNV) system, asymmetric NNV equation, asymmetric DS equation, dispersive long wave equation, Broer-Kaup-Kupershmidt system, long wave-short wave interaction model, Maccari system, and a general (N+M)-component Ablowitz-Kaup-Newell-Segur (AKNS) system. Selecting the arbitrary functions appropriately, one may obtain abundant stable localized interesting excitations such as the multidromions, lumps, ring soliton solutions, breathers, instantons, etc. It is shown that some types of lower dimensional chaotic patterns such as the chaotic-chaotic patterns, periodic-chaotic patterns, chaotic line soliton patterns, chaotic dromion patterns, fractal lump patterns, and fractal dromion patterns may be found in higher dimensional soliton systems. The interactions between the traveling ring type soliton solutions are completely elastic. The traveling ring solitons pass through each other and preserve their shapes, velocities, and phases. Some types of localized weak solutions, peakons, are also discussed. Especially, the interactions between two peakons are not completely elastic. After the interactions, the traveling peakons also pass through each other and preserve their velocities and phases, however, they completely exchange their shapes.

Journal Article↗

PubMed2002

Solutions of a (2+1)-dimensional dispersive long wave equation.

A special type of multisoliton solution with a particular dispersion relation is obtained for Wu-Zhang equation [which describes (2+1)-dimensional dispersive long waves] by the standard Weiss-Tabor-Carnvale Painlevé truncation expansion. Using a nonstandard truncation of a modified Conte's invariant Painlevé expansion, two different types of soliton solutions without any dispersive relation is found. Two types of periodic wave solutions expressed by Jacobi elliptic functions are found by the truncations of a special extended Painlevé expansion. The soliton solutions are special cases of the corresponding periodic solutions.

Journal Article↗