反相气相色谱法表征聚丁二烯橡胶的表面性质

采用反相气相色谱技术测定了聚丁二烯橡胶的表面性质。以正己烷、正庚烷、正辛烷、正壬烷作为非极性探针测定其表面色散自由能,以二氯甲烷、三氯甲烷、丙酮、乙酸乙酯、乙醚和四氢呋喃作为极性探针测定其路易斯酸碱常数。经计算得出聚丁二烯橡胶在303、313、323、333和343 K的表面色散自由能分别为47.07、46.46、45.85、45.60和45.09 mJ/m2。结果表明,聚丁二烯橡胶表面色散自由能随着温度的升高呈线性降低,路易斯酸常数Ka为0.34,碱常数Kb为1.77,总酸碱作用能力2.11,该聚合物为弱碱性Lewis两性聚合物材料。此外还计算出聚丁二烯橡胶的酸碱作用吸附自由能（~ΔGsa）和吸附焓（~ΔHsa）。     

Quantitative analysis of three chiral pesticide enantiomers by high-performance column liquid chromatography

Methods for the enantiomeric quantitative determination of 3 chiral pesticides, paclobutrazol, myclobutanil, and uniconazole, and their residues in soil and water are reported. An effective chiral high-performance liquid chromatographic (HPLC)-UV method using an amylose-tris(3,5-dimethylphenylcarbamate; AD) column was developed for resolving the enantiomers and quantitative determination. The enantiomers were identified by a circular dichroism detector. Validation involved complete resolution of each of the 2 enantiomers, plus determination of linearity, precision, and limit of detection (LOD). The pesticide enantiomers were isolated by solvent extraction from soil and C18 solid-phase extraction from water. The 2 enantiomers of the 3 pesticides could be completely separated on the AD column using n-hexane isopropanol mobile phase. The linearity and precision results indicated that the method was reliable for the quantitative analysis of the enantiomers. LODs were 0.025, 0.05, and 0.05 mg/kg for each enantiomer of paclobutrazol, myclobutanil, and uniconazole, respectively. Recovery and precision data showed that the pretreatment procedures were satisfactory for enantiomer extraction and cleanup. This method can be used for optical purity determination of technical material and analysis of environmental residues.     

Bridgman growth of ZnO crystals from high temperature solution

ZnO single crystals have been grown by the modified vertical Bridgman method from high temperature solution of ZnOPbF₂ system. The initial composition of PbF₂ flux was optimized as 78 mol %. Transparent ZnO crystals with different shapes were grown at a furnace temperature of 1100 °C and a lowering rate of about 0.3 mm/h. XRD patterns showed as-grown ZnO crystals have Wurtzite structure. The growth mechanism was also discussed. PACS 81.10.Dn; 81.05 Dz; 77.84.Bw     

Reactions of 2,3‐dihydro‐1H‐1,5‐benzodiazepines and chloroacetyl chlorides: Synthesis of 2a,3,4,5‐tetrahydro‐azeto [1,2‐a][1,5] benzodiazepin‐1(2H)‐ones

2a,4‐Disubstituted 5‐benzoyl‐2‐chloro/2,2‐dichloro‐2a,3,4,5‐tetrahydro‐azeto [1,2‐a] [1,5]benzodiazepin‐1 (2H)‐ones ( 3a–h ) were synthesized by cycloaddition reactions of 2,4‐disubstituted 1‐benzoyl‐2,3‐dihydr o‐1H‐1,5‐benzodiazepines ( 2a–h ) and ketenes, generated from chloroacetyl chloride or dichloroacetyl chloride in the presence of triethylamine, in anhydrous benzene. In some cases, ring contraction of benzodiazepines has also been observed. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:636–640, 2001     

A sensitive biosensor for lactate based on layer-by-layer assembling MnO2 nanoparticles and lactate oxidase on ion-sensitive field-effect transistors

A sensitive enzyme-based FET biosensor for lactate has been obtained by introducing MnO2 nanoparticles at the gate surface via a layer-by-layer assembling method.     

An example of PDE with two attractors

ＡＮＥＸＡＭＰＬＥＯＦＰＤＥＷＩＴＨＴＷＯＡＴＴＲＡＣＴＯＲＳＷａｎｇＧｕａｎｘｉａｎｇ（王冠香）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ,ＳｕｚｈｏｕＵｎｉｖｅｒｓｉｔｙ,Ｓｕｚｈｏｕ２１５００６Ｐ．Ｒ．Ｃｈｉｎａ）ＸｕＺｈｅｎｙｕａｎ（徐...     

Surface plasmons at the interface between graphene and Kerr-type nonlinear media

The properties of surface plasmons localized at the interface between graphene and Kerr-type nonlinear substrates are investigated analytically. Although the relative propagation distance remains the same, the dispersion of graphene plasmons may be affected much by the inevitable nonlinear effect of substrates. Specifically, the wavelength of graphene plasmons can be tuned by adjusting the nonlinear permittivity of substrates.     

Fabrication of stable, transparent and superhydrophobic nanocomposite films with polystyrene functionalized carbon nanotubes

Stable, transparent and superhydrophobic carbon nanotube (CNT) nanocomposite films were fabricated by one-step spray casting process using the polystyrene functionalized CNTs, which were prepared by “living” free-radical polymerization and analyzed by means of infrared spectroscopy and thermal gravimetric analysis. The CNT film has a high water contact angle of 160° and a sliding angle of less than 3°. The surface topography of the fabricated film was characterized by field emission scanning electron microscopy. The transparency of the CNT film was investigated by UV–vis spectroscopy. The result shows that the CNT film has light transmittance of about 78% in the visible light region.