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By targeted introduction of 6-nitrobenzimidazole into polymolybdate, two new polymolybdate-based copper-organic complexes were successfully synthesized, namely {Cu2(6-nbm)4[β-Mo8O26](H2O)2}·(6-nbm)2·4H2O (1) and H2{Cu2(6-nbm)4[TeMo6O24](H2O)4}·(6-nbm)2·4H2O (2) (6-nbm = 6-nitrobenzimidazole), and structurally characterized by single-crystal X-ray diffraction, IR spectroscopy and powder X-ray diffraction (PXRD). Complexes 1 and 2 are both one-dimensional (1D) chain structures, in which 6-nbm hangs on the 1D chain in a monodentate coordination mode, appearing with a butterfly-like configuration. Complexes 1 and 2 both display bifunctional electrocatalytic activity toward the reduction of KNO2, as well as the oxidation of ascorbic acid (AA). The title complexes, used to prepare bulk-modified carbon paste electrodes (1–CPE and 2–CPE), can be used as electrochemical sensors, which show lower detection limit, good selectivity and anti-interference ability. In addition, the carbon cloth-based electrode modified with complex 1 (1–CC) exhibits ideal capacitance and long-term cycle stability, indicating that complex 1 can be a potential candidate for a pseudocapacitive material. In addition, complexes 1 and 2 show catalytic activity for the CO2 reduction reaction. [ABSTRACT FROM AUTHOR]

Two new polyoxometalate (POM)-based metal–organic supramolecular architectures, [Cu(Hpypa)2(PMo12O40)(μ2-Cl)] 3H2O (1) and [Co(H2bpap)(γ-Mo8O28)0.5(H2O)2] H2O (2), were successfully synthesized by using two self-designed pyrimidine-amide organic ligands [N-(pyridin-3-ylmethyl)pyrimidine-4-carboxamide (pypa) and N,N′-bis(4-pyrimidinecarboxamido)-1,5-pentane (bpap)], as well as Keggin-type POM anions and octamolybdate anions under hydrothermal conditions. Complex 1 is a 1D supramolecular structure containing dinuclear [Cu2(Hpypa)4(PMo12O40)2(μ2-Cl)2] units. Complex 2 exhibits a 3D supramolecular framework consisting of 1D [Co(H2bpap)(H2O)2]n4n+ metal–organic chains and free [Mo8O28]8− anions. The supercapacitor performances of complexes 1 and 2 in a three-electrode system were investigated. When the current density is 1 A g−1, 1 and 2 exhibit specific capacitances of 555 and 675 F g−1, respectively. The symmetrical supercapacitor assembled with complex 2 as the electrode modifier exhibits an energy density of 13.4 W h kg−1 with a power density of 450 W kg−1. Capacitance retention remains at 96% after 6500 cycles. At the same time, the electrochemical sensors prepared with complexes 1 and 2 can be used for the determination of Cr(VI)/Fe(III) ions in aqueous solution with high sensitivity and low detection limit. [ABSTRACT FROM AUTHOR]

In this study, a new ligand, 5-(4-pyrimidinecarboxamido)-1H-tetrazol (4-H2pat), was synthesized by connecting the pyrimidine group and tetrazole group through an amide bond for the first time, aiming to construct new POM-based metal–organic complexes (POMOCs). By using the ligand 4-H2pat, two new POMOCs, [Cu4(4-pat)2(μ2-OH)(CrMo6(OH)6O18)(H2O)3]·2H2O (1) and [Cu2(4-pat)(β-Mo8O26)0.5(H2O)3] (2), were successfully synthesized under solvothermal and hydrothermal conditions, respectively. The structures were characterized by single crystal X-ray diffraction analysis, IR spectroscopy and powder X-ray diffraction (PXRD). In complex 1, the 1D [Cu4(μ2-OH)(4-pat)2]n3n+ metal–organic chains were connected by μ2-bridging [CrMo6(OH)6O18]3− (CrMo6) anions to construct a 2D layered structure. In complex 2, the 2D [Cu2(4-pat)]n2n+ metal–organic grid framework was consolidated by the μ4-bridging [β-Mo8O26]4− (Mo8) anions. The use of two different POM anion clusters results in the formation of two diverse 2D framework structures. Complexes 1 and 2 can effectively catalyze the oxidation of methyl phenyl sulfide as non-homogeneous catalysts with 97% and 95% conversions, respectively. They can also be used as electrocatalysts to prepare bulk-modified electrodes for detecting Cr(VI) and Fe(III) ions with low detection limits. In addition, the effects of different POMs on the structures and catalytic/electrocatalytic performances of the title complexes were discussed. [ABSTRACT FROM AUTHOR]

By designing and using a new flexible bis(pyrimidine)‐bis(amide) ligand H2L [H2L=N,N′‐bis(4‐pyrimidinecarboxamido)‐1,3‐propane], two new polyoxometalate (POM)‐based metal‐organic complexes (MOCs), H3[Cu2(L)2(PMo12O40)] (1) and [Cu2(H2L)2(β‐Mo8O26)] (2), were synthesized under solvothermal and hydrothermal conditions, respectively. In complexes 1 and 2, metal‐organic units and POM anions are linked together to form two distinct 2D structures. The [PMo12O40]3− (PMo12) anions were used as μ4‐bridging ligands in complex 1 and linked the 1D [Cu(L)]n metal‐organic chains to form a 2D layered structure. The [β‐Mo8O26]4− (Mo8) anions adopted two diverse coordination modes in complex 2 and connected the 1D [Cu(H2L)]n2n+ metal‐organic chains to generate a 2D grid structure. Complexes 1–2 can serve as electrode materials of supercapacitor and show large specific capacitances, up to 1065 and 956 F g−1 at current density of 2 A g−1, respectively, which surpass the parent POM and most of the previous reported POM‐based electrode materials, thus demonstrating the important role of introducing metal‐organic units in improving capacitive performances. Besides, the electrocatalytic redox activities of complexes 1–2 were also studied, both of them can be used as electrochemical sensors to detect Cr(VI) ions. They possess high sensitivity of 0.537 and 0.455 μA μM−1 and low detection limits of 0.16 and 0.33 μM, which are below the maximum content of Cr(VI) in groundwater required by the WHO. [ABSTRACT FROM AUTHOR]

Four new isostructural POM-based metal–organic complexes, [H2X2(L)2(TeMo6O24)(H2O)6]·4H2O [X = Cu (1), Co (2), Ni (3) and Zn (4); L = N,N′-bis(4-pyrimidinecarboxamido)-1,4-benzene], were synthesized with a new rigid bis(pyrimidine)-bis(amide) ligand by varying the central metal under hydrothermal conditions, and characterized by means of single crystal X-ray diffraction, IR spectra and powder X-ray diffraction (PXRD). Complexes 1–4 exhibit similar 2D supramolecular structures based on the [H2X2(L)2(TeMo6O24)(H2O)6] dinuclear units linked through hydrogen bonds. Complexes 1–4 not only show good electrochemical sensing properties for BrO3−, NO2−, hydrogen peroxide and ascorbic acid, but can also be used as adsorbents for the removal of organic dyes such as gentian violet and methylene blue. Among them, complex 4 has the lowest detection limit and best dye adsorption capacity. Alternatively, the effect of central metals on the properties of the title complexes was discussed. [ABSTRACT FROM AUTHOR]

Taking rice variety Shennong 265 as test material, a hydroponic experiment was conducted to investigate the effects of Fe (0, 0. 1, 0. 25 and 0. 5 mmol Fe2+·L-1) and Cd (0, 0. 1 and 1. 0 umol Cd2+ ·L-1 ) on the lipid peroxidation and antioxidative enzyme activities of rice plant. When the Fe was supplied alone, the shoot and root dry mass decreased significantly, but this phe-nomenon would not occur when the Cd was applied simultaneously. Applying Cd alone decreased the root malondialdehyde (MDA) and soluble protein contents, but applying Fe simultaneously alleviated the negative effects of Cd. Applying Fe decreased the Cd concentrations in shoots and roots, whereas applying Cd decreased the shoot and root Fe concentrations, indicating an obvious antagonistic interaction between Fe and Cd. The interaction of high concentration (1. 0 μmol·L-1) Cd with Fe increased the root MDA and soluble protein contents, and decreased the root superoxide dismutase (SOD) and catalase (CAT) activities. These results indicated that applying definite amount of exogenous Fe could decrease the Cd accumulation in rice under low Cd stress, whereas high Cd stress would decrease the Fe absorption by rice and induce the lipid peroxidation in rice plant. [ABSTRACT FROM AUTHOR]

To investigate the correlation in growth between A. actinomycetemcomitans and cariogenic bacteria of S. mutans, L. acidophilus, A. naeslundii, A. viscosus in vitro. METHODS: Using improvement agar diffusion method and dual-species (A. actinomycetemcomitans with each of cariogenic bacteria) incubation in BHI broth, we studied the relationship between A. actinomycetemcomitans and 4 kinds cariogenic bacteria in growth. The characteristics and percentage of A. actinomycetemcomitans in dual-species biofilms were detected with SEM and CFU (colony forming units). The data were analyzed for significance using an independent two-sample t test with SPSS 10.0 software package. RESULTS: The agar diffusion essay showed that A. actinomycetemcomitans had no effect on the growth of S. mutans, L. acidophilus, A. naeslundii and A. viscosus. While these 4 kinds of cariogenic bacteria could inhibit the growth of A. actinomycetemcomitans. The ratio of A. actinomycetemcomitans in the dual-species suspension decreased gradually. In dual-species BHI broth, the proportion of A. actinomycetemcomitans cultured alone ahead of 12 hours decreased as well, which came to 0 at 24-hour in S. mutans and L. acidophilus groups. There was significant difference between different time groups (P<0.05). The single A. actinomycetemcomitans was failed to form three-dimensional biofilm and just a small quantity of cells accumulated and adhered. on the contrary, the 4 kinds of single cariogenic bacteria could form mature biofilms respectively by themselves at 48-hour, of which the appearance of biofilms had no apparent change to that of single cariogenic bacteria after mixing A. actinomycetemcomitans. CFU of dual-species biofilms indicated that the percentage of A. actinomycetemcomitans in biofilms decreased gradually by changing medium per 12 hours. These were significant difference among the three time spots (P<0.05). CONCLUSION: The study shows that S. mutans, L. acidophilus, A. naeslundii and A. viscosus could inhibit the growth of A. actinomycetemcomitans in vitro. [ABSTRACT FROM AUTHOR]

Taking rice variety Shennong 265 as test material, a hydroponic experiment was conducted to investigate the effects of Fe (0, 0.1, 0.25 and 0.5 mmol Fe2+ x L(-1)) and Cd (0, 0.1 and 1.0 umol Cd2+ x L(-1)) on the lipid peroxidation and antioxidative enzyme activities of rice plant. When the Fe was supplied alone, the shoot and root dry mass decreased significantly, but this phenomenon would not occur when the Cd was applied simultaneously. Applying Cd alone decreased the root malondialdehyde (MDA) and soluble protein contents, but applying Fe simultaneously alleviated the negative effects of Cd. Applying Fe decreased the Cd concentrations in shoots and roots, whereas applying Cd decreased the shoot and root Fe concentrations, indicating an obvious antagonistic interaction between Fe and Cd. The interaction of high concentration (1.0 micromol x L(-1)) Cd with Fe increased the root MDA and soluble protein contents, and decreased the root superoxide dismutase (SOD) and catalase (CAT) activities. These results indicated that applying definite amount of exogenous Fe could decrease the Cd accumulation in rice under low Cd stress, whereas high Cd stress would decrease the Fe absorption by rice and induce the lipid peroxidation in rice plant.

To study the solubilization of breviscapine with polyamidoamine (PAMAM) dendrimers and probe the solubilizing mechanism and investigate the influence of PAMAM dendrimers on the pharmacokinetics of breviscapine, the solubilization of breviscapine by PAMAM dendrimers of generations G1, G1.5, G2 and G2.5 with different concentrations were determined and compared in different pH conditions. Twelve rats randomized into 2 groups were separately orally administered breviscapine and breviscapine combining with PAMAM. Drug in plasma was extracted and determined with HPLC. In pH condition lower than 7.0, the solubilization of breviscapine by PAMAM dendrimers enhanced as the generation and concentration of PAMAM dendrimers as well as the pH increased. Its solubilizing mechanism involves an electrostatic interaction between the carboxyl group of breviscapine and the primary amines and tertiary amines of PAMAM dendrimers. The pharmacokinetics parameters Cmax and AUC0-8 h of breviscapine were (119.65 +/- 9.36) ng x mL(-1) and (370.09 +/- 63.08) ng x h x mL(-1). For breviscapine combined with PAMAM dendrimers, the Cmax and AUC0-8 h were (518.17 +/- 17.07) ng x mL(-1) and (1,219.47 +/- 201.87) ng x h x mL(-1), respectively. There were significant differences of AUC0-8 h between breviscapine and breviscapine combined with PAMAM dendrimers (P < 0.01). PAMAM dendrimers can greatly increase the solubility of breviscapine in water and can improve the oral bioavailability of breviscapine significantly.

Purpose: To investigate the correlation in growth between A.actinomycetemcomitans and cariogenic bacteria of S.mutans, L.acidophilus A.naeslundii A.viscosus in vitro., Methods: Using improvement agar diffusion method and dual-species (A.actinomycetemcomitans with each of cariogenic bacteria) incubation in BHI broth, we studied the relationship between A.actinomycetemcomitans and 4 kinds cariogenic bacteria in growth. The characteristic and percentage of A.actinomycetemcomitans in dual-species biofilms were detected with SEM and CFU(colony forming units).The data were analyzed for significance using an independent two-sample t test with SPSS 10.0 software package., Results: The agar diffusion essay showed that A.actinomycetemcomitans had no effect on the growth of S.mutans, L.acidophilus A.naeslundii and A.viscosus. While these 4 kinds of cariogenic bacteria could inhibit the growth of A.actinomycetemcomitans. The ratio of A.actinomycetemcomitans in the dual-species suspension decreased gradually.In dual-species BHI broth, the proportion of A.actinomycetemcomitans cultured alone ahead of 12 hours decreased as well, which came to 0 at 24-hour in S.mutans and L.acidophilus groups. There was significant difference between different time groups(P<0.05).The single A.actinomycetemcomitans was failed to form three-dimensional biofilm and just a small quantity of cells accumulated and adhered. On the contrary, the 4 kinds of single cariogenic bacteria could form mature biofilms respectively by themselves at 48-hour,of which the appearance of biofilms had no apparent change to that of single cariogenic bacteria after mixing A.actinomycetemcomitans. CFU of dual-species biofilms indicated that the percentage of A.actinomycetemcomitans in biofilms decreased gradually by changing medium per 12 hours. There were significant difference among the three time spots(P<0.05)., Conclusion: The study shows that S.mutans, L.acidophilus A.naeslundii and A.viscosus could inhibit the growth of A.actinomycetemcomitans in vitro.

Background: Cecropin-XJ belongs to cecropin-B, which is the most potent antibacterial peptide found naturally. The aim of this study was to investigate the effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria., Methods: Four oral cariogenic bacteria (Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscosus and Actinomyces naeslundii) were chosen for this experiment. The minimal inhibitory concentrations (MICs) and reductive percent of bacterial growth were used to assay the antibacterial activity of cecropin-XJ. Mammalian cytotoxicity of cecropin-XJ was tested with human periodontal membrane fibroblasts by tetrazolium (MTT) colorimetric assay. The bacterial morphological changes induced by cecropin-XJ were examined on scanning electron microscope (SEM). The influence of cecropin-XJ on bacterial adhesion to saliva-coated hydroxyapatite (S-HA) was measured by scintillation counting., Results: The MICs of cecropin-XJ for inhibition of the growth of four bacteria ranged from 4.0 to 42.8 micromol/L with the highest susceptible to A. naeslundii and the lowest susceptible to L. acidophilus. At pH 6.8, 5.5 and 8.2, 1/2 MIC of cecropin-XJ reduced the number of viable bacteria by 40.9%, 67.8% and 32.8% for S. mutans and by 28.1%, 57.2% and 37.9% for L. acidophilus. The activities against S. mutans and L. acidophilus increased at pH 5.5 compared with pH 6.8 (P < 0.01, respectively). In present of 50% saliva, 1/2 MIC of the peptide decreased the direct count of viable cells by 29.2% and 14.4% for S. mutans and L. acidophilus, respectively (P < 0.01 and P > 0.05, respectively), whereas almost no reduction counts were detected in the presence of 20% serum for both bacteria (P > 0.05, respectively). Mammalian cytotoxicity of cecropin-XJ from 1.0 to 100 micromol/L exhibited no cytotoxicity against human periodontal membrane fibroblasts (P > 0.05). Bacterial morphological changes induced by MIC of cecropin-XJ examined on SEM showed cell surface disruption. Furthermore, the ability of A. naeslundii adhesion to S-HA decreased significantly with MIC of cecropin-XJ for 10 and 20 minutes (P = 0.001 and 0.000, respectively), and S. mutans, A. viscosus to S-HA decreased significantly with MIC of cecropin-XJ for 20 minutes (P = 0.000, respectively)., Conclusions: Cecropin-XJ exhibited bactericidal action against cariogenic pathogens, and the antibacterial activity enhanced in the acid environment. The results also demonstrate that cecropin-XJ prevents S. mutans and actinomyces adsorption to S-HA. These findings suggest that Cecropin-XJ may have potential to prevent caries.