超临界水中聚乙烯油化的研究

采用125mL间歇式高压釜反应器，在超临界水条件下考察了反应温度、反应时间、水/聚乙烯比和水填充率对聚乙烯降解油化的影响。实验结果表明,聚乙烯在超临界水中迅速降解，油收率可达90%以上；随温度从450℃提高到480℃，油收率从91.4％下降到61.7％，气体收率从1.9％提高到27.7％；在450 ℃反应时间从1 min延长到30 min时，油收率略有下降，油品中C7-11组分所占比例增大一倍。水/聚乙烯比和水填充率的增加在一定程度上对聚乙烯的降解起抑制作用。     

Non‐Isothermal Decomposition Kinetics,Specific Heat Capacity and Adiabatic Time‐to‐explosion of a Novel High Energy Material: 1‐Amino‐1‐Methylamino‐2,2‐Dinitroethylene (AMFOX‐7)

A novel high energy material, 1‐amino‐1‐methylamino‐2,2‐dinitroethlyene (AMFOX‐7), was synthesized by the reaction of 1,1‐diamino‐2,2‐dinitroethylene (FOX‐7) and methylamine aqueous solution in N‐methyl pyrrolidone at 80°C. The thermal behavior and non‐isothermal decomposition kinetics of AMFOX‐7 were studied with DSC and TG/DTG methods. The kinetic equation of thermal decomposition reaction can be expressed as: $ {\rm d\alpha /d}T = \frac{{10^{21.03}}}{{\rm \beta}}\frac{3}{2}\left({1 - {\rm \alpha}} \right)\left[{- 1{\rm n}\left({{\rm 1} - {\rm \alpha}} \right)} \right]^{\frac{1}{3}} \exp \left({- 2.292 \times 10^5 {\rm /}RT} \right) A novel high energy material, 1‐amino‐1‐methylamino‐2,2‐dinitroethlyene (AMFOX‐7), was synthesized by the reaction of 1,1‐diamino‐2,2‐dinitroethylene (FOX‐7) and methylamine aqueous solution in N‐methyl pyrrolidone at 80°C. The thermal behavior and non‐isothermal decomposition kinetics of AMFOX‐7 were studied with DSC and TG/DTG methods. The kinetic equation of thermal decomposition reaction can be expressed as: $ {\rm d\alpha /d}T = \frac{{10^{21.03}}}{{\rm \beta}}\frac{3}{2}\left({1 - {\rm \alpha}} \right)\left[{- 1{\rm n}\left({{\rm 1} - {\rm \alpha}} \right)} \right]^{\frac{1}{3}} \exp \left({- 2.292 \times 10^5 {\rm /}RT} \right) $. The critical temperature of thermal explosion of AMFOX‐7 is 244.89°C. The specific heat capacity of AMFOX‐7 was determined with micro‐DSC method and theoretical calculation method, and the standard molar specific heat capacity is 199.39 J·mol^?1·K^?1 at 298.15 K. Adiabatic time‐to‐explosion of AMFOX‐7 was also calculated to be 215.41 s. AMFOX‐7 has higher thermal stability than FOX‐7.     

Determination of faropenem in human plasma and urine by liquid chromatography-tandem mass spectrometry

A simple, rapid and sensitive liquid chromatography/electrospray tandem mass spectrometry (LC-MS/MS) quantitative detection method, using cefalexin as internal standard, was developed for the analysis of faropenem in human plasma and urine. After precipitation of the plasma proteins with acetonitrile, the analytes were separated on a C18 reversed-phase column with 0.1% formic acid-methanol (45:55, v/v) and detected by electrospray ionization mass spectrometry in positive multiple reaction monitoring mode. Calibration curves with good linearities (r=0.9991 for plasma sample and r=0.9993 for urine sample) were obtained in the range 5-4000 ng/mL for faropenem. The limit of detection was 5 ng/mL. Recoveries were around 90% for the extraction from human plasma, and good precision and accuracy were achieved. This method is feasible for the evaluation of pharmacokinetic profiles of faropenem in humans, and to our knowledge, it is the first time the pharmacokinetic of faropenem has been elucidated in vivo using LC-MS/MS.     

Purification of deoxynivalenol from Fusarium graminearum rice culture and mouldy corn by high-speed counter-current chromatography

Deoxynivalenol (DON) is a mycotoxin produced by several Fusarium species and is toxic to a wide range of organisms, including human beings and livestock. To produce large amounts of pure DON for research purposes, a novel method using high-speed counter-current chromatography (HSCCC) was developed. Rice cultured with Fusarium graminearum and field mouldy corn infected by F. graminearum were extracted with methanol and found to contain 1.16 and 1.30 mg DON/g, respectively. The extracts were concentrated and then separated using a biphasic solvent system consisting of ethyl acetate-water (1:1, v/v). Collected fractions were analyzed by high-performance liquid chromatography (HPLC) and identified by congruent retention time and UV/vis spectrum and mass spectrometric data. Fractions containing DON were combined and freeze-dried. This method produced 116 mg and 65 mg DON with a purity of greater than 94.9% from 200 g of the rice culture and the mouldy corn, respectively. The HSCCC method had a recovery rate of DON at 88% from the crude extracts of both samples. This one-step purification method provided a simple and effective tool for obtaining a large amount of DON, an essential material for studies related to toxicology and detoxification of this mycotoxin.     

Temperature-sensitive polypeptide brushes-coated mesoporous silica nanoparticles for dual-responsive drug release

A multifunctional nanohybrid based on mesoporous silica nanoparticle and biocompatible polypeptide was fabricated for targeted and dual-responsive therapy of tumor cells.     

CHLOROPHYLL PHOTOSENSITIZED ELECTRON TRANSFER IN PHOSPHOLIPID VESICLE SYSTEMS: COMPARISON OF INSIDE-OUTSIDE ASYMMETRY BETWEEN LARGE AND SMALL UNILAMELLAR VESICLES*

Abstract— We have determined the chlorophyll triplet quenching efficiencies, the chlorophyll cation radical yields and the conversion efficiencies of chlorophyll triplet to radical in large and small unilamellar phosphatidylcholine vesicles (LUV and SUV, respectively) in the presence of electrically-charged electron acceptors (ferricyanide and oxidized cytochrome c) located in either the inner or outer aqueous compartments of the vesicles. Both types of vesicles displayed inside-outside asymmetry, although the properties were reversed. Triplet quenching in SUV was more efficient when ferricyanide was located within the vesicle interior, whereas the reverse was true in LUV. When ferricyanide was located on the outside of the vesicles, the extent of triplet quenching in LUV was about two times that in SUV and the amount of cation radical formed in LUV was about two times that in SUV. Under these conditions, the conversion efficiencies of chlorophyll triplet to radical were 12.2% for LUV and 8.5% for SUV. With cytochrome c as an electron acceptor in negatively charged vesicles (25 mol per cent dixhexadecylphosphate incorporated) similar results were obtained. Again, the triplet quenching and radical yield inside-outside asymmetry properties were reversed between the two types of vesicles, and radical formation efficiencies when cyt c was located outside the vesicles were higher in LUV (11.7%) than in SUV (4.2%). We conclude that the inside-outside asymmetric photochemical behavior of unilamellar phosphatidylcholine vesicles is influenced by factors in addition to the difference in radius of curvature between the inside and outside surfaces. It is suggested that transmembrane electrostatic potentials may be involved. Furthermore, in the present system the properties of LUV were more favorable to photochemical electron transfer product formation than those of SUV.     

Preparation of multihollow P(St-MAA) particles by sequence soap-free/soap emulsion polymerization and followed by stepwise alkali/acid posttreatment

The effects of ionic emulsifier, sodium dodecylbenzene sulfate (SDBS), on the formation of the multihollow structures in sub-micron sized polymer particles produced by alkali/acid posttreatment were investigated. The original latex particles with narrow size distribution were synthesized by a new sequence emulsifier-free/emulsifier emulsion copolymerization of styrene (St) and methacrylic acid (MAA). Results indicated that the pore size decreased and the pore number increased with the increase of SDBS amount, and the morphology of the posttreated latex particles was also significantly influenced by the introducing time of SDBS in the preparation of the original latex particles, and a suitable introducing time was 3 h of polymerization.     

Influence of the built-in pyridinium salt on asymmetric epoxidation of substituted chromenes catalysed by chiral (pyrrolidine salen)Mn(III) complexes

Chiral (pyrrolidine salen)Mn(III) complexes 1 with an N-benzoyl group and 2 with an N-isonicotinoyl group as well as the corresponding N-methyl (3) and N-benzyl (4) pyridinium salts of 2 were synthesized. The catalytic properties of 1–4 and 2 with excess CH₃I were explored to figure out the influence of the internal pyridinium salt in the catalyst on asymmetric epoxidation of substituted chromenes with NaClO/PPNO as an oxidant system in the aqueous/organic biphasic medium. The (pyrrolidine salen)Mn(III) complexes with an internal pyridinium salt, either formed in situ or isolated, displayed higher activities than analogous complexes 1, 2 and Jacobsen's catalyst in the aforementioned reaction, with comparable high yields and ee values. The acceleration of the reaction rate is attributed to the phase transfer capability of the built-in pyridinium salt of the (salen)Mn(III) catalyst. The effect of the internal pyridinium salt on the epoxidation of substituted chromenes is similar to that of the external pyridinium salts and ammonium halides.     

Ultrafast Dynamics of o‐Bromofluorobenzene Studied by Time‐Resolved Photoelectron Imaging

Photodissociation dynamics and rotational wave packet coherences of o‐bromofluorobenzene are studied by femtosecond time‐resolved photoelectron imaging (see figure). The decay of different photoelectron rings shows the population decay of states from which the lifetimes of different states are determined. The variation of photoelectron angular distributions reflects the evolution of rotational coherences.

     

Characterization of porcine skin as a model for human skin studies using infrared spectroscopic imaging

Porcine skin is often considered a substitute for human skin based on morphological and functional data, for example, for transdermal drug diffusion studies. A chemical, structural and temporal characterization of porcine skin in comparison to human skin is not available but will likely improve our understanding of this porcine skin model. Here, we employ Fourier transform infrared (FT-IR) spectroscopic imaging to holistically measure chemical species as well as spatial structure as a function of time to characterize porcine skin as a model for human skin. Porcine skin was found to resemble human skin spectroscopically and differences are elucidated. Cryo-prepared fresh porcine skin samples for spectroscopic imaging were found to be stable over time and small variations are observed. Hence, we extended characterization to the use of this model for dynamic processes. In particular, the capacity and stability of this model in transdermal diffusion is examined. The results indicate that porcine skin is likely to be an attractive tool for studying diffusion dynamics of materials in human skin.