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961.
Zhenhu Cao Yan ZhangPingan Song Yuanzheng Cai Qi GuoZhengping Fang Mao Peng 《Journal of Analytical and Applied Pyrolysis》2011,92(2):339-346
A novel metal chelate complex containing phosphorus, nitrogen and zinc (II) ion was synthesized and used as the flame retardant of low density polyethylene (LDPE). The zinc chelate complex was synthesized by reacting zinc acetate with the ligand of tetraethyl (1,2-phenylenebis(azanediyl)) bis (2-hydroxylphenylmethylene) diphosphonate (TEPAPM). The chemical structure of the target Zn-TEPAPM was confirmed by FTIR, 1H NMR, 13C NMR and 31P NMR spectra. The flame retardancy and thermal behavior of LDPE containing various amount of Zn-TEPAPM were investigated by limiting oxygen index test, thermogravimetric (TG) analysis and cone calorimetry. The results show that Zn-TEPAPM can greatly increase the thermal stability, the char formation and smoke suppression ability of LDPE. The TG curves show that even when the filler content of Zn-TEPAPM is as low as 1 wt% in LDPE, the onset degradation temperature of LDPE is increased from 429 °C to 442 °C, and the maximum degradation temperature is increased from 469 °C to 488 °C. Also, a reduction of 32% for the peak heat release rate (PHRR) is obtained in the cone test. Moreover, Zn-TEPAPM is demonstrated to be a very effective synergist of ammonium polyphosphate (APP). When 1 wt% of Zn-TEPAPM was introduced into the LDPE/APP (mass ratio 80/19) blend, the PHRR value is reduced by 32%, compared with that of LDPE/APP blend without Zn-TEPAPM, and the char layer becomes more compact and intact. 相似文献
962.
A simple, rapid and sensitive CE-ESI-MS method for the simultaneous analysis of seven stimulants and narcotics (amphetamine, ephedrine, methadone, pethidine, tetracaine, codeine and heroin) was developed. The CE-ESI-MS experimental conditions were optimized as follows: 20?mmol/L ammonium acetate with pH 9.0 as running buffer, the separation voltage of 22?kV and the sheath liquid of isopropanol/water (1:1 v/v) containing 7.5?mmol/L acetic acid with 3.0?μL/min flow rate. Under the optimized conditions, the stimulants and narcotics were well separated within 4.6?min using a 70-cm length fused-silica capillary (50?μm id). The detection limits (S/N=3) of the CE-ESI-MS analysis were in the range of 0.40-1.0?ng/mL. Method repeatability of intra-day and inter-day was satisfactory. The recoveries obtained from the analysis of spiked urine samples were between 84.1 and 108%. The developed method was successfully applied for the simultaneous analysis of methadone, pethidine and codeine and their in vitro metabolites. 相似文献
963.
Cluster studies have attracted much interest in the past decades because of their extraordinary properties. To describe the interaction between atoms or molecules and predict the energies and structures, potential functions are developed. However, different potentials generally produce different structures and energies for a cluster. To study the effect of potentials on the structure of a cluster, He clusters in the size range of 13-140 are investigated by Lennard-Jones (LJ), Pirani, and Hartree-Fock-dispersion individual damping (HFD-ID) potential with dynamic lattice searching (DLS) method. Potential function curves, cluster structures, bonds, and energies of the global minima are compared. The results show that cluster energies decrease with the values of the potential functions, the differences between structures depend upon the disagreements of the potentials, and the preferable motif of a cluster changes from icosahedron to decahedron with the increase of the derivative of the short-range part of the potentials. 相似文献
964.
Abstract
A tetrazole-supported polymeric ligand has been synthesized. The palladium complex derived from the polymeric material has been evaluated as a catalyst for the Heck reaction of aryl iodides and bromides with styrene to provide the corresponding products in high yields. The reaction proceeded smoothly in the presence of 1 mol% with respect to Pd of catalyst in DMF at 125 or 140 °C within 1–3 h. Recycling studies showed that the catalyst can be readily recovered and reused for several times without significant loss of catalytic activity. 相似文献965.
Sheng-Li Chen Haitao Wang Guimei Yuan Zhiqing Wang Zhi Cai 《Transition Metal Chemistry》2011,36(4):441-445
Macro-/mesoporous Al2O3 supports were prepared by using monodisperse polystyrene (PS) microspheres as a template. The pore volume and BET surface
area of the Al2O3 supports increased considerably with increasing amounts of the PS microspheres; further investigation showed that PS template
only increased the volume of macro-pores but did not change the volume of meso-pores or micro-pores. Macro-/mesoporous Re2O7/Al2O3 metathesis catalysts were prepared through loading Re2O7 onto the as-prepared macro-/mesoporous Al2O3 supports, and their catalytic performance was tested in a fixed-bed tubular reactor using the metathesis of normal butylenes
as a probe reaction. The results showed that the prepared macro-/mesoporous Re2O7/Al2O3 catalyst had high activity with consistent selectivity; propylene and pentene accounted for more than 90 wt% of the metathesis
products, while the amount of ethylene plus hexane was less than 10 wt%, the majority of which was hexane. These Re2O7/Al2O3 catalysts had not only higher activity, but also longer working life span and higher tolerance to carbon residues than conventional
Re2O7/Al2O3 catalysts. 相似文献
966.
A facile and high-throughput strategy is presented to fabricate three-dimensional (3D) hierarchically porous Ag films, with clean surfaces, via plasma etching Ag-coated electrospun nanofiber template. The films are built of Ag porous nanotubes and are homogeneous in macro-size but rough and porous in nanoscale. Each nanotube-block is micro/nanostructured with evenly distributed nanopores on the tube walls. The film architecture (or the shape, arrangement, and distribution density of porous nanotubes; the number and size of nanopores) can be easily controlled by the nanofiber-template configuration, Ag coating, and plasma etching conditions. Such hierarchically porous films could be very useful, such as in catalysis, sensors, and nanodevices. They have exhibited significantly structurally enhanced surface-enhanced Raman scattering performance with good stability and reproduction, and shown the possibility of molecule-level detection. Also, the strategy is universal for fabricating other hierarchically structured 3D metal porous films, such as porous Ag hollow sphere arrays. 相似文献
967.
968.
Amphiphilic cholesteryl 2,6-di-O-methyl-β-cyclodextrins (chol-DIMEB) can self-aggregate into spherical micelles of noteworthy potential for drug delivery. All-atom molecular dynamics simulations of chol-DIMEB micelles consisting of 3-24 monomers have been performed in aqueous solution. chol-DIMEB exhibits a pronounced tendency to self-assemble into core-shell structures. van der Waals interactions within the cholesteryl nucleus constitute the main driving force responsible for the formation of the micelle. The calculated radii of the hydrophobic core and of the hydrophilic shell for the micellar structure formed by 24 monomers agree well with the experiment. The cyclodextrin moieties are found to be exposed toward the aqueous medium and possess the appropriate flexibility to capture drugs in an effective fashion. Analysis of the solvent accessible surface area and hydration number indicates that the micelles are highly hydrosoluble species and can, therefore, enhance significantly the aqueous solubility of lipophilic drugs. In addition, the spatial structure of the micelles is suggestive of multiple potential drug binding sites. The present contribution unveils how micelles endowed with specific characteristics can form, while opening exciting perspectives for the design of novel micellar nanoparticles envisioned to be drug carriers of high potential. 相似文献
969.
A series of surfaces with microscale checkerboard patterns consisting of continuous central lines and discontinuous lateral lines were fabricated. The surface wetting properties of these checkerboard patterns were found to be anisotropic. The central continuous lines were found to have a strong influence on the dynamic wetting properties and moving trajectories of the water droplets. The droplets move more easily in the direction parallel to the central continuous lines and less easily in the direction perpendicular to the central continuous lines. Meanwhile, the droplets' moving path tends to incline toward the central continuous lines from a tilting direction. When the microsurface was modified with a layer of nanowire, the surface wettability was found to be isotropic and superhydrophobic. 相似文献
970.
Cai X Tan S Lin M Xie A Mai W Zhang X Lin Z Wu T Liu Y 《Langmuir : the ACS journal of surfaces and colloids》2011,27(12):7828-7835
A water-soluble brilliant blue/reduced graphene oxide/tetradecyltriphenylphosphonium bromide composite (BB-rGO-TTP) was prepared by using noncovalent brilliant blue-functionalized reduced graphene oxide (BB-rGO) as the tetradecyltriphenylphosphonium bromide (TTP) carrier. Antibacterial performance of this novel composite was investigated for both Gram-positive and Gram-negative bacteria. The results showed that the novel BB-rGO-TTP, combing the advantages of graphene and TTP, displayed excellent synergistic antibacterial activity, specific targeting capability, water solubility, and mild cytotoxicity, suggesting the great potential application as sprayable graphene-based antibacterial solutions. 相似文献