辛基羟肟酸浮选氟碳铈矿机制研究

采用纯矿物浮选的方法,以松醇油为起泡剂,研究了氟碳铈矿在辛基羟肟酸钠为捕收剂体系下的浮选行为,在p H=7~11范围内,氟碳铈矿回收率大于96%,尤其在p H=9附近,氟碳铈矿的可浮性最好,回收率接近100%;采用傅立叶红外光谱(FT-IR)和X射线光电子能谱(XPS)手段进行作用机制研究,红外光谱表明,辛基羟肟酸钠在氟碳铈矿表面发生了化学吸附;XPS结果表明,氟碳铈矿表面可能只存在-C=O-RE-O-N-一种五元环螯合物;结合La3+和Ce3+离子溶液化学和氟碳铈矿浮选行为,推测La(OH)2+,La(OH)2+,Ce(OH)2+和Ce(OH)2+是存在于氟碳铈矿表面的浮选活性点,并推测了辛基羟肟酸在氟碳铈矿表面作用的模型。     

一种卡宾配合物的合成及其在Suzuki反应中的应用

合成了一种N-杂环卡宾的钯配合物,可用于高效地催化芳基溴化物和对甲苯磺酸芳酯对芳基硼酸的Suzuki偶联反应.该反应在二氧六环溶剂中以醋酸钾为助剂、空气氛下80℃即可进行,具有收率高、催化剂容易制备等优点.     

In Vitro Photodynamic Inactivation Effects of Ru(II) Complexes on Clinical Methicillin‐resistant Staphylococcus aureus Planktonic and Biofilm Cultures

Photosensitizers (PSs) combined with light are able to generate antimicrobial effects. Ru(II) complexes have been recognized as a novel class of PSs. In this study, we investigated the effectiveness of photodynamic inactivation (PDI) mediated by three Ru(II) polypyridine complexes, 1–3, against four isolates of clinical methicillin‐resistant Staphylococcus aureus (MRSA‐1, MRSA‐2, MRSA‐3 and MRSA‐4). In PDI of a planktonic culture of MRSA‐1, compound 3 showed the highest efficacy, likely owing to its advantageous light absorption, ¹O₂ quantum yield and bacterial cellular binding. The PDI efficacy of 3 was further evaluated against all other strains and MRSA‐1 biofilms. At appropriate PS concentrations, viability reduction of 100% or 96.83% was observed in planktonic or biofilm forms of MRSA, respectively. The mechanisms of action were investigated using negative staining transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). It was demonstrated that PDI of planktonic bacteria was achieved primarily through damage to the cell envelope. Biofilms were eliminated through both the destruction of their structure and inactivation of the individual bacterial cells. In conclusion, Ru(II) complexes, especially 3, are potential candidates for the effective photodynamic control of MRSA infections.     

Electrochemical performance of a nano SnO2-modified LiNi1/3Co1/3Mn1/3O2 cathode material

The nano SnO₂-modified LiNi_1/3Co_1/3Mn_1/3O₂ was successfully prepared by a carrier transfer method. The pristine and modified samples were characterized with various techniques such as XRD, SEM, XPS and EDS. The results showed that the SnO₂ particles did not enter the crystal structure of LiNi1/3Co1/ 3Mn1/3O₂, many nano SnO₂ particles were uniformly covered on the surface of LiNi_1/3Co_1/3Mn_1/3O₂ and the modified thin layer could inhibit the dissolution of transition metal oxides. The electrochemical tests indicated that the existence of nano SnO₂ could improve the discharge capacity and rate capability owing to the decreased interfacial polarization. The cycling stability was remarkably improved at room temperature and 55 ℃. The XRD patterns of the fresh NCM electrode and after 50 cycles proved that the structural change of NCM was not so effective on the capacity fade.     

Direct Conversion of Bulk Metals to Size‐Tailored,Monodisperse Spherical Non‐Coinage‐Metal Nanocrystals

Monodisperse non‐noble metal nanocrystals (NCs) that are highly uniform in shapes and particle size are much desired in various advanced applications, and are commonly prepared by either thermal decomposition or reduction, where reactive organometallic precursors or/and strong reducing agents are mandatory; however, these are usually toxic, costly, or suffer a lack of availability. Bulk Group 12 metals can now be converted into ligand‐protected, highly crystalline, monodisperse spherical metal NCs with precisely controlled sizes without using any precursors and reducers. The method is based on low‐power NIR‐laser‐induced size‐selective layer‐by‐layer surface vaporization. The monodisperse Cd NCs show pronounced deep‐UV (DUV) localized surface plasmon resonance making them highly competitive DUV‐plasmonic materials. This approach will promote appreciably the emergence of a wide range of monodisperse technically important non‐coinage metal NCs with compelling functionalities.     

Synthesis and magnetic properties of organic multilayer films based on the layer‐by‐layer assembly

Two polymers containing pyridine rings were prepared by free‐radical polymerization and confirmed by Fourier transform infrared and ¹H NMR spectra. The preparation of four multilayer films that were obtained by self‐assembly of the polymer and the transition metal neutralized polyelectrolyte on PE substrate was described. UV–vis spectra and atomic force microscopy images were applied to characterize these films and indicate the uniform assembling process. The driving force for building up the multilayer films was identified by infrared spectroscopy to be the coordination interaction. The magnetic behavior was examined as a function of magnetic field strength at 30 kOe and as a function of temperature (5–300 K). All films display strong soft ferromagnetic properties and higher than those of the bulk materials. The magnetic results show that the layer‐by‐layer self‐assembling approach is beneficial to the ordered alignment of adjacent paramagnetic spins and induces better magnetic phenomena. Copyright © 2015 John Wiley & Sons, Ltd.     

Highly fluorescent polycaprolactones decorated with di(thiophene‐2‐yl)‐diketopyrrolopyrrole: A covalent strategy of tuning fluorescence properties in solid states

Well‐defined 1,4‐diketo‐3,6‐di(thiophen‐2‐yl)pyrrolo[3,4‐c]pyrrole (DTDPP) labeled polycaprolactones (PCL) with different chain lengths were synthesized and characterized. The effect of polymer chain lengths on the optical properties of DTDPP in solid states was studied by UV‐Vis absorption spectroscopy as well as steady‐state and dynamic fluorescence spectroscopies. Our results indicate that when the PCL side chain is extended to a certain length, the intermolecular aggregation of DTDPP units can be reduced significantly due to segregation effect of PCL. This approach offers a new facile strategy to address the common problem of aggregation‐caused quenching existing in organic fluorophores. These highly fluorescent biodegradable PCL polymers may find broad biomedical applications such as fluorescence‐based bioimaging and tissue engineering. © 2015 Wiley Periodicals, Inc. J. Polym. Sci. Part A: Polym. Chem. 2015 , 53, 1032–1042     

Preparation of 17β‐estradiol‐imprinted material by surface‐initiated atom transfer radical polymerization and its application

A novel 17β‐estradiol molecularly imprinted polymer was grafted onto the surface of initiator‐immobilized silica by surface‐initiated atom transfer radical polymerization. The resulting molecularly imprinted polymer was characterized by elemental analysis and thermogravimetric analysis. The binding property of molecularly imprinted polymer for 17β‐estradiol was also studied with both static and dynamic methods. The results showed that the molecularly imprinted polymer possessed excellent recognition capacity for 17β‐estradiol (180.65 mg/g at 298 K), and also exhibited outstanding selectivity for 17β‐estradiol over the other competitive compounds (such as testosterone and progesterone). Then, the determination of trace 17β‐estradiol in beef samples was successfully developed by using molecularly imprinted polymer solid‐phase extraction coupled with high‐performance liquid chromatography. The limit of detection was 0.25 ng/mL, and the amount of 17β‐estradiol in beef samples was detected at 2.83 ng/g. This work proposed a sensitive, rapid, reliable, and convenient approach for the determination of trace 17β‐estradiol in complicated beef samples.     

Inverse colloidal crystal membranes for hydrophobic interaction membrane chromatography

Hydrophobic interaction membrane chromatography has gained interest due to its excellent performance in the purification of humanized monoclonal antibodies. The membrane material used in hydrophobic interaction membrane chromatography has typically been commercially available polyvinylidene fluoride. In this contribution, newly developed inverse colloidal crystal membranes that have uniform pores, high porosity and, therefore, high surface area for protein binding are used as hydrophobic interaction membrane chromatography membranes for humanized monoclonal antibody immunoglobulin G purification. The capacity of the inverse colloidal crystal membranes developed here is up to ten times greater than commercially available polyvinylidene fluoride membranes with a similar pore size. This work highlights the importance of developing uniform pore size high porosity membranes in order to maximize the capacity of hydrophobic interaction membrane chromatography.     

Determination of selected polychlorinated biphenyls in soil and earthworm (Eisenia fetida) using a QuEChERS‐based method and gas chromatography with tandem MS

Soil and earthworms are important objects in soil pollution assessment and environmental behavior and toxicity study for polychlorinated biphenyls. Accelerated solvent extraction and solid‐phase extraction are generally required for the extraction and clean‐up of polychlorinated biphenyls in soil and earthworm, which are tedious and time‐consuming. In this work, a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure combined with gas chromatography and triple quadrupole mass spectrometry was developed for the determination of 20 selected polychlorinated biphenyl congeners in soil and earthworm. Different extraction times, solvents, and clean‐up adsorbents were compared and optimized. The average recoveries from spiked soils ranged between 70 and 120% with satisfactory relative standard deviations for all the polychlorinated biphenyls. In earthworm, the recoveries of polychlorinated biphenyls 180, 183, and 189 were relatively low (< 70% in some spiking levels) compared to that of the other polychlorinated biphenyls. The limits of quantification were in the range of 0.01–0.05 ng/g. The method was successfully applied to the analysis of 66 agricultural soils. To our knowledge, a combined method based on QuEChERS for the determination of polychlorinated biphenyls in soil and earthworms has not been published before. The procedure proved to be simple, sensitive, efficient, and environmentally friendly.