棉花植株及土壤中丙硫克百威及其代谢物残留气相色谱测定

研究超声波提取、毛细管气相色谱配氮磷检测器(NPD)检测棉花植株及土壤中丙硫克百威及其代谢物残留 ,各组分回收率83%～110 % ,线性范围0.1～100mg/L,最低检测质量分数0.01×10-6～0.02×10-6(w) ;该法具有简单、快速、节省试剂的特点     

Stereocontrolled assembly of tetrasubstituted tetrahydrofurans: a concise synthesis of virgatusin

The condensation of substituted allylsiloxanes with aldehydes leads to the highly stereoselective construction of 2,3,4,5-tetrasubstituted tetrahydrofurans. With electron-rich aryl and alpha,beta-unsaturated aldehydes as substrates, the stereochemical outcome at C5 can be dictated by appropriate choice of Lewis acid. The reaction has been applied to a concise (nine step) synthesis of (+)-virgatusin (ent-1). [reaction: see text]     

The synthesis of 1-amino-2-hydroxy- and 2-amino-1-hydroxy-substituted ethylene-1,1-bisphosphonic acids and their N-methylated derivatives

A synthesis of 2-amino-1-hydroxyethylene-1,1-bisphosphonic acid 3 has been developed from N-phthaloylglycine via dimethyl 2-(N-phthaloylamino)acetylphosphonate 1. The preparation of the N-methylated and N,N-dimethylated derivatives 4 and 5 has been achieved by the reaction of 3 with formic acid and formaldehyde. The synthesis of 1-amino-2-hydroxyethylene-1,1-bisphosphonic acid 9 (R=R′=H) and its N-methylated and N,N-dimethylated analogues has been achieved by the reaction of phosphorus trichloride and phosphorous acid with the appropriate O-benzyl protected hydroxyacetamide, followed by catalytic hydrogenolysis of the protecting group.     

Inverted colloidal crystals as three-dimensional cell scaffolds

A new type of three-dimensional scaffold with inverted colloidal crystal geometry for the investigation of topological effects in cell cultures is introduced in this publication. The scaffolds are made by infiltration of the hexagonal crystal lattice of polystyrene spheres with sol-gel formulation and subsequent annealing. It possesses a relatively high degree of order among existing cell scaffolds and affords tight control over the scaffold porosity and tissue organization. The prepared scaffolds can be a convenient system for the investigation of cell-cell and cell-matrix interactions. Their biocompatibility is demonstrated for human hepatocellular carcinoma HEP G2 and human bone marrow HS-5 cell cultures. A preliminary effect of the scaffold topology on cell proliferation is observed. HEP G2 hepatocytes form a large number of 10-15 cell colonies on scaffolds made from 75-microm spheres, while their number diminishes for scaffolds from 10- and 160-microm spheres. Under similar conditions, HS-5 forms smaller colonies consisting of three to four cells in 90-microm cavities.