聚醚酯嵌段共聚物熔体的流变性能

采用毛细管流变仪测定了组成比、聚醚分子量、熔融时间和熔融温度对嵌段聚醚酯熔体表观粘度的影响．结果发现在所研究的温度和切变速率范围内,该结构聚醚酯熔体为假塑性非牛顿流体,其粘度随聚酯段含量的增加而增加,随熔融时间增加而降低,随聚醚分子量的增大而增大．聚醚酯的零切粘度可由Ｓｐｅｎｃｅｒ Ｄｉｌｌｏｎ 公式外推得到,零切粘度对温度的依赖关系服从Ａｎｄｒａｄｅ 公式．     

二(对-氯苄基)二氯化锡的合成及晶体结构

用 X射线方法测定了二 (对氯苄基 )二氯化锡的晶体结构,该化合物晶体属单斜晶系,空间群为 C2/c,晶体学参数： a=2.8010(3), b=0.4882(2), c=1.2174(3)nm,β =111.71(1)°, V=1.5467(7) nm3, Z=4, Dx=1.893g· cm－ 3,μ (MoKα )=23.24cm－ 1, F(000)=856.00, R=0.025, Rw=0.038, Sn C键长为 0.2148(3)nm, Sn Cl键长为 0.23754(9)nm。空间构型为畸变四面体构型的单分子有机锡化合物。     

沟槽面湍流边界层结构实验研究

应用激光测速技术和氢气泡流动显示技术对沟槽面湍流边界层特性及近壁区拟序结构特征进行了精细的测量和观察。实验结果表明：与光滑面湍流边界层相比,沟槽面端流边界层的黏性底层厚度、过渡层厚度及流速分布对数公式中的积分常数C均有所增大,说明采用的沟槽面具有减阻特性。此外,无量纲低速带条间距明显减小,最多减小20%,说明无量钢低速带条平均间距的缩短与湍流减阻密切联系。     

Propagations of Rayleigh and Love waves in ZnO films/glass substrates analyzed by three-dimensional finite element method

Propagation characteristics of surface acoustic waves(SAWs) in ZnO films/glass substrates are theoretically investigated by the three-dimensional(3D) finite element method. At first, for(11ˉ20) ZnO films/glass substrates, the simulation results confirm that the Rayleigh waves along the [0001] direction and Love waves along the [1ˉ100] direction are successfully excited in the multilayered structures. Next, the crystal orientations of the ZnO films are rotated, and the influences of ZnO films with different crystal orientations on SAW characterizations, including the phase velocity, electromechanical coupling coefficient, and temperature coefficient of frequency, are investigated. The results show that at appropriate h/λ, Rayleigh wave has a maximum k~2 of 2.4% in(90°, 56.5°, 0°) ZnO film/glass substrate structure; Love wave has a maximum k~2 of 3.81% in(56°, 90°, 0°) ZnO film/glass substrate structure. Meantime, for Rayleigh wave and Love wave devices, zero temperature coefficient of frequency(TCF) can be achieved at appropriate ratio of film thickness to SAW wavelength. These results show that SAW devices with higher k~2 or lower TCF can be fabricated by flexibly selecting the crystal orientations of ZnO films on glass substrates.     

1-丁基-3-甲基咪唑氯盐-水和2，6-二甲氧基苯酚混合物中分子相互作用的衰减全反射红外光谱研究

Molecular interactions of the ternary mixtures of 1-butyl-3-methylimidazolium chloride ([C₄C₁im]Cl)-water-2,6-dimethoxyphenol (2,6-DMP, a phenolic monomer lignin model compound) were investigated in comparison with the [C₄C₁im]Cl-water binary systems through attenuated total reflection infrared spectroscopy. Results indicated that the microstructures of water and [C₄C₁im]Cl changed with varying mole fraction of [C₄C₁im]Cl (^xIL) from 0.01 to 1.0. This change was mainly attributed to the interactions of [C₄C₁im]Cl-water and the self-aggregation of [C₄C₁im]Cl through hydrogen bonding. The band shifts of C-H on imidazolium ring and the functional groups in 2,6-DMP indicated that the occurrence of intermolecular interactions by different mechanisms (i.e., hydrogen bonding or π-π stacking) resulted in 2,6-DMP dissolution. In the case of ^xIL=0.12, the slightly hydrogen-bonded water was fully destroyed and [C₄C₁im]Cl existed in the form of hydrated ion pairs. Interestingly, the maximum 2,6-DMP solubility (238.5 g/100 g) was achieved in this case. The interactions and microstructures of [C₄C₁im]Cl-water mixtures influenced the dissolution behavior of 2,6-DMP.     

两种新香豆素分子的热力学和光谱性质

使用密度泛函理论方法在B3LYP /6-31++G**理论水平对两种香豆素a和b分子的几何结构、光谱、热力学性质进行理论计算研究,并基于Tomasi的极化统一场模型(PCM)讨论溶剂效应。结果显示,香豆素a和b分子在气相中的最低能量吸收波长分别为352和355 nm,溶剂及其极性大小对香豆素a最低能量吸收波长影响很小,但在溶剂作用下香豆素b分子的最低能量吸收波长红移7-10 nm,溶剂的极性对该波长影响较小。298 K标准压力下香豆素a和b分子的气态标准摩尔生成焓 分别为-1373.171和-1310.805 kJ.mol-1,标准摩尔生成自由能 分别为-1064.043和-1035.849 kJ.mol-1,标准摩尔熵 分别为763.910和742.150 J.mol-1.K-1.     

PdCl_2催化芳基硼酸与溴代芳烃Suzuki-Miyaura偶联反应的机理研究

采用密度泛函理论(DFT)中的M06方法,以二甲基甲酰胺(DMF)溶剂,研究了无催化剂、PdCl_2为催化剂催化芳基硼酸与溴代芳烃的交叉偶联反应的反应机理.使用6-311+G*基组(Pd采用赝势基组Lan L2DZ)对芳基硼酸与溴代芳烃Suzuki-Miyaura偶联反应过程中所有反应物、中间体、过渡态和产物的几何构型进行了优化,同时进行了频率计算,各过渡态都有唯一虚频,确认了中间体和过渡态的合理性;通过自然键轨道(NBO)理论和分子内原子理论(AIM)理论分析了分子轨道间的相互作用.结果发现:在没有催化剂的条件下,Suzuki-Miyaura偶联反应形成的反应速控步骤活化能为49.70 kcal/mol,在PdCl_2催化作用下,反应速控步骤活化能为31.08 kcal/mol,比较研究结果,PdCl_2能有效催化该反应的进行,我们的研究结果与实验结果相吻合.     

紫外光区S_2分子激光诱导荧光光谱

利用真空脉冲放电超声射流气体束(H_2S/Ar~3%混合气体)的方法产生了气相S_2分子,并研究了30 400~34 400cm~(-1)范围内S_2分子的时间分辨和基态振动频率分辨的激光诱导荧光光谱,获得了184支谱带的高分辨率(0.1cm~(-1))和低分辨率(0.3cm~(-1))转动光谱。实验观测并归属了S_2分子B_u~(Σ-)-X~3Σ_g~-和B″~3Π_u-X~3Σ_g~-共84支振动跃迁,分析得到了激发态B~3Σ_u~-态ν=0~9和B″~3Π_u态ν=2~12的分子常数以及B~3Σ_u~-态的基态平衡分子构型。由于S_2分子B~3Σ_u~-与B″~3Π_u态之间存在微扰,这两个电子激发态的振动能级间隔、自旋分裂常数和自旋-轨道分裂常数变化不规律,转动跃迁强度和跃迁选择定则存在异常,利用~3Σ-~3Π的齐次微扰哈密顿量定性地对这些异常光谱进行了解释,进一步丰富了S_2分子紫外区低能电子激发态的信息。     

Sniffing lung cancer related biomarkers using an oxidized graphene SAW sensor

Decane is one of the volatile organic compounds (VOCs) in human breath. Successful detection of decane in human breath has vast prospects for early lung cancer diagnosis. In this paper, a novel detecting device based on a filter surface acoustic wave (SAW) gas sensor is presented. SAW sensors coated with a thin oxidized graphene film were used to detect decane in parts per million (ppm) concentrations. Control and signal detection circuits were designed using a vector network analyzer with a detection resolution of insertion loss down to 0.0001 dB. The results showed that the SAW sensor could respond quickly with great sensitivity when exposed to 0.2 ppm decane. This device shows tremendous potential in medical diagnosis and environmental assessment.     

化学溶液法制备的Pb(Mg1/3 Nb2/3)O3-PbTiO3薄膜的光学性能

用化学溶液方法在宝石衬底及有LaNiO3缓冲层的Pt/TiO2/SiO2/Si衬底上制备了92%Pb(Mg1/3 Nb2/3)O3-8%PbTiO3(PMNT)薄膜,X射线衍射测试结果表明:在有LaNiO3缓冲层的Pt/TiO2/SiO2/Si衬底上制备的PMNT薄膜几乎是纯钙钛矿相,且薄膜呈现(110)择优取向.通过对Pt/TiO2/SiO2/Si衬底上的PMNT薄膜在2.5-12.6μm波长范围内的红外椭圆偏振光谱测试,并拟合得到了PMNT薄膜在2.5-12.6μm波长范围内的光学常数(n和k),通过对宝石衬底上的PMNT薄膜在200-1100nm波长范围内的可见-紫外透过率测试,并拟合得到了PMNT薄膜在200-1100nm波段的光学常数(n和k)和吸收系数α,进而推导出PMNT薄膜的禁带宽度为4.03eV.