Predicting the occurrence of antagonism within ternary guanidine mixture pollutants based on the concentration ratio of components.

The widespread prevalence and coexistence of diverse guanidine compounds pose substantial risks of potential toxicity interactions, synergism or antagonism, to environmental organisms. This complexity presents a formidable challenge in assessing the risks associated with various pollutants. Hence, a method that is both accurate and universally applicable for predicting toxicity interactions within mixtures is crucial, given the unimaginable diversity of potential combinations. A toxicity interaction prediction method (TIPM) developed in our past research was employed to predict the toxicity interaction, within guanidine compound mixtures. Here, antagonism were found in the mixtures of three guanidine compounds including chlorhexidine (CHL), metformin (MET), and chlorhexidine digluconate (CDE) by selecting Escherichia coli (E. coli) as the test organism. The antagonism in the mixture was probably due to the competitive binding of all three guanidine compounds to the anionic phosphates of E. coli cell membranes, which eventually lead to cell membrane rupture. Then, a good correlation between toxicity interactions (antagonisms) and components' concentration ratios (pis) within binary mixtures (CHL-MET, CHL-CDE, MET-CDE) was established. Based on the correlation, the TIPM was constructed and accurately predicted the antagonism in the CHL-MET-CDE ternary mixture, which once again proved the accuracy and applicability of the TIPM method. Therefore, TIPM can be suggested to identify or screen rapidly the toxicity interaction within ternary mixtures exerting potentially adverse effects on the environment.

Poly[[tetrachlorido{µ4-tetrakis[(pyridin-4-yl)oxymethyl]methane-κ4N:N':N'':N'''}dizinc(II)] dimethylformamide tetrasolvate].

A novel metal-organic framework, {[Zn2Cl4(C25H24N4O4)]·4C3H7NO}n, has been synthesized solvothermally by assembling the semi-rigid tetrahedral ligand tetrakis[(pyridin-4-yl)oxymethyl]methane (tpom) and zinc nitrate in dimethylformamide (DMF). The crystal structure is noncentrosymmetric (P42(1)c). Each Zn(II) cation has a tetrahedral coordination environment (C2 symmetry), which is formed by two chloride ligands and two pyridine N atoms from two tpom ligands. The tetrahedral tetradentate tpom linker has a quaternary C atom located on the crystallographic -4 axis. This linker utilizes all the peripheral pyridine N atoms to connect four Zn(II) cations, thereby forming a wave-like two-dimensional sheet along the c axis. The two-dimensional layer can be topologically simplified as a typical uninodal 4-connected sql/Shubnikov net, which is represented by the Schläfli symbol {4(4),6(2)}. Adjacent layers are further packed into a three-dimensional structure by C-H···Cl hydrogen bonds.

Rapid sonochemical synthesis of irregular nanolaminar-like Bi2WO6 as efficient visible-light-active photocatalysts.

Irregular Bi(2)WO(6) nanolaminars have been successfully synthesized via a rapid sonochemical approach using bismuth nitrate and tungstic acid as precursors in an aqueous solution. The characteristics of them were investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N(2) adsorption, pore value, PL spectroscopy and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). These irregular nanolaminars are of geometric shapes of orthorhombic Bi(2)WO(6) with their basal plane being (001). They possess high crystallinity, lager surface area and pore value, which means fewer traps and stronger photocatalytic activity. The growth mechanism of such special nanolaminar was related to the sonochemical synthesis route, which played a key role in the formation of Bi(2)WO(6) nanolaminar. Simultaneously, it was found that the formation of Bi(2)WO(6) nanolaminar is a time dependent process. The Bi(2)WO(6) nanolaminar has higher photocatalytic activity than bulk Bi(2)WO(6) nanoparticle obtained by refluxing method for rhodamine B (Rh.B) degradation under visible light irradiation (λ>400 nm).

[Parallel factor analysis as an analysis technique for the ratio of three-dimensional fluorescence peak in Taihu Lake].

The present paper proposes a new method to find the ratio of three-dimensional fluorescence peak. At first, the excitation-emission fluorescence matrix of water samples was treated with parallel factor analysis (PARAFAC) and then fluorescence peaks intensity and ratio of fluorescence peak were obtained from the parallel factor analysis model. From the parallel factor analysis model, the same fluorescence peaks of different water samples lie at the same excitation-emission wavelength and the overlap of different fluorescence peaks of the same water sample is reduced. Analysing regional characteristic in Taihu Lake, the ratio of factor score and the ratio of fluorescence peak showed strong correlation.

Thioacetamide chemically immobilized on silica gel as a solid phase extractant for the extraction and preconcentration of copper(II), lead(II), and cadmium(II).

Thioacetamide immobilized on silica gel was prepared via the Mannich reaction. The extraction and enrichment of copper(II), lead(II), and cadmium(II) ions from aqueous solutions has been investigated. Conditions for effective extraction are optimized with respect to different experimental parameters in both batch and column processes prior to their determination by flame atomic absorption spectrometry (FAAS). The optimum pH ranges for quantitative adsorption are 4.0-8.0, 2.0-7.0, and 5.0-10.0 for Pb(II), Cu(II), and Cd(II), respectively. Pb(II) and Cd(II) can be desorbed with 3 mol/L and 0.1 mol/L HCl/HNO3, and Cu(II) can be desorbed with 2.5% thiourea. The adsorption capacity of the matrix has been found to be 19.76, 16.35, and 12.50 mg/g for Pb(II), Cu(II), and Cd(II), respectively, with the preconcentration factor of approximately equal to 300 for Pb(II) and approximately equal to 200 for Cu(II) and Cd(II). Analytical utility is illustrated in real aqueous samples generated from distilled water, tap water, and river water samples.