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Zinc and cadmium are two main transition metal ions and play profound important roles in environmental and human health. But the distinctive detection of these two ions is still challenging since they belong to the same periodic group and have similar chemical properties. A fluorescent bipyridine-based porous organic polymer (Bpy-POP) containing aggregation caused quenching (ACQ) units (anthracene) and metal ions recognition units (bipyridine) was synthesized through the Schiff base condensation reaction. In the DMF/H2O mixtures with the water fractions of 90%, the Bpy-POP aggregated and the fluorescent Bpy-POP quenched subsequently due to the ACQ effect of anthracene in the skeleton (“OFF” state). With the addition of Zn2+ or Cd2+, however, the strong coordination of the bipyridine units from the adjacent Bpy-POPs with Zn2+ or Cd2+ induced the partial dispersion of large Bpy-POP aggregates. Consequently, the fluorescence intensities enhanced dramatically as well as the fluorescence emission shifted to redder region, showing an “ON” state. Combing the fluorescence increasing efficiency and the maximum emission wavelength shift degree together, Zn2+ and Cd2+ can be selectively discriminated and quantitatively detected, which exhibits a great promising of the present Bpy-POP based method in Zn2+ and Cd2+ monitoring in real samples.

Engineered CdS@NC composites were fabricated via the carbonization of a crystalline complex comprised by cadmium cations and methyl orange anions, [Cd(H2O)6(C14H14N3SO3)2] 1, and were developed as viable photocatalysts for enhanced hydrogen (H2) production under visible irradiation with a H2 evolution rate of ca. 7428.0 μmol h−1 g−1, which was relatively high for CdS–based nanomaterials reported hitherto.

Tungsten trioxide hydrate (WO3⋅1/3H2O) nanoparticles (NPs) were prepared via a microwave–assisted synthetic pathway by using Na2WO4·2H2O and PdCl2 as precursors. Microstructure and morphology of as–prepared WO3⋅1/3H2O NPs were investigated through X–ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FT–IR) spectra, while porosity and bandgap through specific surface area and UV–vis absorption spectroscopy. It was found that Pd2+ ions played a crucial role in the formation of WO3⋅1/3H2O NPs, and thus a possible formation mechanism was proposed based on the growth processes. The photocatalytic property of WO3⋅1/3H2O NPs was evaluated on the basis of Rhodamine B (RhB) degradation in aqueous solutions under simulated visible irradiation. Photocatalytic experimental results indicated that as–prepared WO3⋅1/3H2O NPs exhibited much more superior photocatalytic activity by contrast to that of the commercial WO3.

Sodium hexametaphosphate was shown to form a complex with acridine orange by electrostatic interactions that induce fluorescence quenching. Analysis of fluorescence intensity showed that the process was dominated by static quenching, which was confirmed by absorption spectra and lifetime of the excited state. The decreased fluorescence intensity was directly proportional to the concentration of sodium hexametaphosphate between 8.0 × 10−7 and 1.1 × 10−5 mol L−1 with a limit of detection of 5.3 × 10−7 mol L−1. Beverages were analyzed for sodium hexametaphosphate with recoveries between 91.7% and 108.3%.

The selective adsorption of single-stranded oligonucleotides (ssDNA) on gold nanoparticles (AuNPs) is well known for stabilizing the AuNPs against aggregation even at high salt concentrations. Our investigation shows that the non-crosslinking aggregation of arbitrary ssDNA-capped AuNPs occurs due to their interaction with the cationic polyamine, spermine (Spm), even without any addition of NaCl. The non-crosslinking aggregation mechanism is that the Spm, served as multivalent counterions, plays the dual roles of charge shielding and ion bridging among the ssDNA-capped AuNPs, which jointly result in the aggregation of the ssDNA-capped AuNPs. Therefore, a sensitive and highly selective colorimetric method for the detection of Spm was developed. To the best of our knowledge, it is the first successful case as to the efforts towards the development of optical assays for cationic polyamine, showing neither natural UV absorption nor fluorescence. Compared with the traditional methods of chromatography and capillary electrophoresis, the approach described here would provide a convenient alternative and new train of thought for the specific detection of Spm in both biological fluid and fermented products.

The reaction of Zn(Ac)2·2H2O with N-(2-propionic acid)-salicyloyl hydrazone, a tridentate ligand (C10H10N2O4, H3L), and imidazole (C3H4N2), a monodentate ligand, in MeOH:H2O = 3:1 (V/V) yields [Zn(HL)(C3H4N2)(H2O)]. The crystal structure has been determined by X-ray diffraction. In the compound, it crystallizes with two independent molecules in the unit and the two molecules are linked by an intermolecular hydrogen bond and one short contact. Zn is five-coordinated by one tridentate hydrazone ligand, one imidazole, and one water molecule. The coordination polyhedron around Zn(II) described as a distorted square-pyramid. In addition, antibacterial activities of the complex against coliform were investigated by turbidimetry/spectrometry.

A series of transition metal complexes of the general formula M(HL)2 (where H2L=2′-(4-dimethylaminobenzylidene)-2-hydroxybenzoylhydrazide, M=Ni, Cu, Zn, Cd) were prepared and characterized by elemental analysis, spectroscopic (IR, UV–vis) and the Ni(HL)2 was structurally characterized by X-ray crystallography. Single-crystal X-ray diffraction results suggest that Ni(II) central atom situated in a distorted square planar geometry is four-coordinated. The DNA-binding properties of these complexes with calf thymus DNA were also investigated by electronic absorption titration (UV spectroscopy) and fluorescence emission titration. The results showed that these complexes bind to DNA mainly via intercalative mode.

Carbon nanotubes (CNTs) can efficiently quench the fluorescence of the adsorbed fluorophores and nonconvalently interact with soft single-stranded DNA (ssDNA). Upon disruption of CNTs–fluorescent oligonucleotides hybrid by nuclease S1, fluorescence turn-on was observed. Using this strategy, a platform based on fluorescence signal for monitoring the activity of nuclease with advantages of high sensitivity and commonality was established, and a linear relationship between initial cleavage reaction rate and nuclease S1 concentration is found in the range of 0.6–8.0 U mL −1 with a detection limit of 0.08 U mL −1 . Furthermore, by taking pyrophosphate as an example, we use the assay to evaluate the prohibition effect on nuclease, and the extent of fluorescence recovery decreased linearly with increasing the concentration of pyrophosphate in the range of 0.2–1.4 mM, implying that the cleavage reaction by nuclease S1 was prohibited, and therefore this fluorescence assay can also be conveniently utilized for inhibitor screening of nuclease.

Here, we present the electroporation as a feasible and efficient method for introducing circularized and linearized DNA into Bacillus subtilis chromosome. Two integration experiments were carried out and demonstrated the feasibility and efficiency of electroporation to introduce the target DNA into the B. subtilis chromosome. By using of electroporation, a multiple-cistron contained five genes from B. subtilis biotin biosynthetic pathway was introduced into the B. subtilis chromosome efficiently and created a repeated copy in chromosome via a single crossover event. Then an ectopic promoter was introduced conveniently into the upstream of one of the repeated multiple-cistron via a double crossover event. To further demonstrate the application of electroporation in genetic research, the early sporulation gene spo0A of B. subtilis was knocked out and, consequently, the null of sporulation and logged growth was observed in this study. Thus, the electroporation as an alternative method of integration in B. subtilis is feasible and practical.

Two NHC–Pd(II) complexes synthesized from trans-cyclohexane-1,2-diamine were fairly effective in the NHC–Pd(II) complex/Cu co-catalyzed terminal alkyne homocoupling reaction to give the corresponding symmetrical 1,4-disubstituted 1,3-diynes in good yields under mild conditions. Copyright © 2006 John Wiley & Sons, Ltd.

A new dimeric bidentated NHC–Pd(II) complex was synthesized from trans-cyclohexane-1,2-diamine and its structure was characterized by MALDI Mass spectrum. This NHC–Pd(II) complex was fairly effective in Suzuki and Heck reactions to give the products in good to excellent yields in most cases.

A stable dimeric mono-coordinated NHC-Pd(II) complex with bridging iodine atoms was synthesized and characterized by single-crystal X-ray diffraction. It has been successfully applied to the Suzuki-Miyaura cross-coupling reaction under aerobic conditions. Good to excellent yields were obtained in most cases with the addition of H2O. Copyright (c) 2005 John Wiley & Sons, Ltd.

Objective: T o investigatethe effects on histocompatibility and biodegradability of bioabsor bablepolylacticacid (PLA) gelin rats. Methods: Longitudinal incision of 30 mm was made along the spine, and subcutaneous tissues were separated bluntly to make four subcutaneous pouches, and PLA gel of different molecular weight (5, 10 and 20 kD) was implanted into the pouches. 4, 7, 11 and 14 weeks after implantation, the samples and surrounding tissues were collected to perform HE staining; meanwhile, the samples were weighted and compared after drying. Re sults: There were few inflammatory cells accumulations in tissues treated with different molecular weight PLA gel. The degradation rate of 5 kD-PLA gel was faster than other groups. With increase of the molecular weight of PLA gel, the degradation rate was gradually decreased. Conclusion: Our findings indicated that PLA gel had good biocompatibility and a definite de grading effect, which could be further used in surgery.

As a precursor, pimelic acid plays an important role in biotin biosynthesis pathway of Bacillus subtilis. Fermentations supplemented with pimelic acid could improve the production of biotin, however, with a disadvantage-high cost. So it is necessary to improve the biosynthesis of pimelic acid via genetic engineering in B. subtilis. In this study, we constructed a recombinant B. subtilis strain for improving the synthesis of pimelic acid, in which a maltose-inducible Pglv promoter was inserted into the upstream of the cistron bioI-orf2-orf3 and, meanwhile, flanked by the tandem cistrons via a single crossover event. The copy number of the integrant was amplified by high-concentration resistance screen and increased to 4-5 copies. The production of pimelic acid from multiple copies integrant was about 4 times higher than that from single copy (1017.13 μg/ml VS. 198.89 μg/ml). And when induced by maltose the production of pimelic acid was about 2 times of that under non-induction conditions (2360.73 μg/ml VS. 991.59 μg/ml). Thus, these results demonstrated that the production of pimelic acid was improved obviously through reconstructed B. subtilis. It also suggested that our expression system provided a convenient source of pimelic acid that would potentially lower the cost of production of biotin from engineered B. subtilis.

A simple method for phosphate (Pi) detection is established by developing an off–on fluorescence probe of europium-adjusted carbon dots (CDs), which has been successfully applied to the detection of Pi in very complicated matrixes such as artificial wetlands system.