污泥基吸附剂对亚甲基蓝和环丙沙星的吸附性能研究

亚甲基蓝和环丙沙星是水体中2种污染物, 对生态环境有潜在危害. 本文以市政剩余活性污泥为原料, 氯化锌为活化剂热解制备污泥基吸附剂, 研究盐酸酸洗浓度、氯化锌浓度、热解温度、热解时间等对污泥基吸附剂吸附水中亚甲基蓝和环丙沙星性能的影响. 结果表明 (1)污泥基吸附剂对亚甲基蓝的吸附性能随盐酸酸洗浓度的增大而增加, 对环丙沙星的吸附性能则随盐酸酸洗浓度的增大呈先降后增趋势, 两者均在1.500mol·L-1盐酸浓度下取得最优值. (2)污泥基吸附剂对亚甲基蓝和环丙沙星的吸附性能随氯化锌浓度和热解温度的增加呈先升后降趋势, 在氯化锌浓度为4.0mol·L-1、热解温度为500℃时有最优值; 随着热解时间的延长, 污泥基吸附剂对亚甲基蓝和环丙沙星的吸附性能分别在500℃热解70min和80min时有最优值. (3)污泥基吸附剂的最佳制备条件为 氯化锌4.0mol·L-1活化2h、500℃热解70min和80min、1.500mol·L-1盐酸酸洗; 以此制得的污泥基吸附剂对亚甲基蓝和环丙沙星的去除率分别为97.7%和96.4%, 平衡吸附量分别为97.9mg·g-1和3.9mg·g-1, 且污泥基吸附剂对亚甲基蓝和环丙沙星的吸附过程均符合准二级动力学方程.     

Triostin A Derived Cyclopeptide as Architectural Template for the Alignment of Four Recognition Units

The DNA bisintercalator triostin A is structurally based on a disulfide-bridged depsipeptide scaffold that provides preorganization of two quinoxaline units in 10.5 Å distance. Triostin A analogues are synthesized with nucleobase recognition units replacing the quinoxalines and containing two additional recognition units in between. Thus, four nucleobase recognition units are organized on a rigid template, well suited for DNA double strand interactions. The new tetra-nucleobase binders are synthesized as aza-TANDEM derivatives lacking the N-methylation of triostin A and based on a cyclopeptide backbone. Synthesis of two tetra-nucleobase aza-TANDEM derivatives is established, DNA interaction analyzed by microscale thermophoresis, cytotoxic activity studied and a nucleobase sequence dependent self-aggregation investigated by mass spectrometry.     

A rapid,highly efficient,and general protocol for the synthesis of functionalized triarylmethanes: a straightforward access for the synthesis of (−)-tatarinoid C

A rapid, efficient, and convenient synthesis of functionalized triarylmethane is described by the Friedel–Crafts alkylation of methoxybenzenes with a variety of aldehydes in the presence of BF₃·OEt₂. The generality of the method is demonstrated by screening a variety of di- or tri-substituted arenes as well as substituted aromatic, heteroaromatic, and aliphatic aldehydes. (−)-Tatarinoid C is synthesized in a single step following the same protocol.     

FRET Enhancement in Aluminum Zero‐Mode Waveguides

Zero‐mode waveguides (ZMWs) can confine light into attoliter volumes, which enables single molecule fluorescence experiments at physiological micromolar concentrations. Of the fluorescence spectroscopy techniques that can be enhanced by ZMWs, Förster resonance energy transfer (FRET) is one of the most widely used in life sciences. Combining zero‐mode waveguides with FRET provides new opportunities to investigate biochemical structures or follow interaction dynamics at micromolar concentrations with single‐molecule resolution. However, prior to any quantitative FRET analysis on biological samples, it is crucial to establish first the influence of the ZMW on the FRET process. Here, we quantify the FRET rates and efficiencies between individual donor–acceptor fluorophore pairs that diffuse into aluminum zero‐mode waveguides. Aluminum ZMWs are important structures thanks to their commercial availability and the large amount of literature that describe their use for single‐molecule fluorescence spectroscopy. We also compared the results between ZMWs milled in gold and aluminum, and found that although gold has a stronger influence on the decay rates, the lower losses of aluminum in the green spectral region provide larger fluorescence brightness enhancement factors. For both aluminum and gold ZMWs, we observed that the FRET rate scales linearly with the isolated donor decay rate and the local density of optical states. Detailed information about FRET in ZMWs unlocks their application as new devices for enhanced single‐molecule FRET at physiological concentrations.     

High-speed monitoring of the crystallinity change in poly(lactic acid) during photodegradation by using a newly developed wide area NIR imaging system (Compovision)

We aimed to achieve wide area rapid monitoring of the crystallinity change in poly(lactic acid) (PLA) during photodegradation caused by ultraviolet (UV) light by using a newly developed near-infrared (NIR) camera (Compovison). Several kinds of PLA samples with different crystallinities and their blends with poly[(3)-(R)-hydroxybutyrate] were prepared. Their two-dimensional NIR spectra in the 1,000–2,350-nm region were measured by Compovision at a 5-min interval during photolysis. An intensity decrease of the band in the 1,900-1,925-nm region due to the second overtone of the C = O stretching vibration of PLA was observed during photolysis. This suggests that an anhydride carbonyl is produced during photolysis. The NIR image of the crystallinity change monitored by the band at 1,917 nm in the standard normal variate spectra clearly shows the inhomogeneity of crystal evolution. A logarithmic increase was observed for all identified areas in the PLA film; however, the time to reach the maximum crystallinity was slightly different according to the initial crystallinity of the sample. It is likely that the initial crystallinity of the sample influences the degradation speed more than the degradation amount. These imaging results have provided fundamental chemical insights into the photolytic process for PLA, and at the same time they have demonstrated that the two-dimensional spectral data obtained by Compovision are useful for process monitoring of polymers.     

The case of triethylammonium cation loss during purification of certain nucleotide analogues: a cautionary note

Nucleotides, their analogues, and other phosphate esters and phosphoramidates often contain the triethylammonium cation as a counterion. We found that this may be lost during chromatographic purification or concentration of solutions, yielding products in acidic forms or containing sub-stoichiometric amounts of the counterion. This in turn may be detrimental, e.g., due to possible decomposition of a compound or inaccurate sample preparation. Correlations between the structure of studied compounds and their susceptibility for cation loss were analyzed. Modifications in preparative techniques were developed to obtain the studied compounds with stoichiometric anion to cation ratios.

?

Open image in new window

Graphical Abstract Triethylammonium salts of phosphate esters and phosphoramidates may lose the cationic component during chromatography or evaporation of solvent

     

Assessing the role of chemical components in cellular responses to atmospheric particle matter (PM) through chemical fractionation of PM extracts

In order to further our understanding of the influence of chemical components and ultimately specific sources of atmospheric particulate matter (PM) on pro-inflammatory and other adverse cellular responses, we promulgate and apply a suite of chemical fractionation tools to aqueous aerosol extracts of PM samples for analysis in toxicity assays. We illustrate the approach with a study that used water extracts of quasi-ultrafine PM (PM_0.25) collected in the Los Angeles Basin. Filtered PM extracts were fractionated using Chelex, a weak anion exchanger diethylaminoethyl (DEAE), a strong anion exchanger (SAX), and a hydrophobic C18 resin, as well as by desferrioxamine (DFO) complexation that binds iron. The fractionated extracts were then analyzed using high-resolution sector field inductively coupled plasma mass spectrometry (SF-ICPMS) to determine elemental composition. Cellular responses to the fractionated extracts were probed in an in vitro rat alveolar macrophages model with measurement of reactive oxygen species (ROS) production and the cytokine tumor necrosis factor-α (TNF-α). The DFO treatment that chelates iron was very effective at reducing the cellular ROS activity but had only a small impact on the TNF-α production. In contrast, the hydrophobic C18 resin treatment had a small impact on the cellular ROS activity but significantly reduced the TNF-α production. The use of statistical methods to integrate the results across all treatments led to the conclusion that sufficient iron must be present to participate in the chemistry needed for ROS activity, but the amount of ROS activity is not proportional to the iron solution concentration. ROS activity was found to be most related to cationic mono- and divalent metals (i.e., Mn and Ni) and oxyanions (i.e., Mo and V). Although the TNF-α production was not significantly affected by the chelexation of iron, it was greatly impacted by the removal of organics with the C18 resin and all other metal removal methods, suggesting that iron is not a critical pathway leading to TNF-α production, but a wide range of soluble metals and organic compounds in particulate matter play a role. Although the results are specific to the Los Angeles Basin, where the samples used in the study were collected, the method employed in the study can be widely employed to study the role of components of particulate matter in in vitro or in vivo assays.