驻波情形的液体声光效应的理论与实验研究

模拟计算了液体声光衍射的贝塞尔函数,测量了不同质量分数NaCl溶液对激光的衍射效率和不同温度纯水对激光衍射的相对光强比,计算了不同质量分数NaCl溶液的声光相位延迟、声致折射率变化量幅值.结果表明:随着NaCl溶液质量分数的增加,声光衍射效率、相对光强比、声致折射率变化量幅值均不同程度下降,而温度对纯水的相对光强比影响很小.     

Attenuation correction for dedicated breast PET using only emission data based on consistency conditions

Accurate attenuation correction is required in dedicated breast PET imaging systems for image artifact removal and quantitative studies. In this study, a method using only emission data based on consistency conditions is proposed for attenuation correction in breast PET imaging systems. The consistency conditions are exploited to evaluate the accuracy of the estimated attenuation distribution and find the appropriate parameters that yield the most consistent attenuation distribution with the measured emission data. We have proved the validity of the method with experimental investigations and single-patient studies using a dedicated breast PET. The results show that the method is capable of accurately estimating the attenuation distribution of a uniform attenuator from the experimental data with various relatively low activities. The results also show that in single-patient studies, the method is robust for the irregular boundary of breast tissue and provides a distinct improvement in image quality.     

Multi-Slit Diffraction of Evanescent Electromagnetic Waves

The well-known Fraunhofer multi-slit diffraction is described as the multi-slit interference modulated by the singleslit diffraction, namely the multiplication between the single-slit diffraction factor and the multi-slit interference factor. By considering the simplified argument we show that the multi-slit diffraction of evanescent waves which are in the near-field region also has the interference and diffraction effects, and that this two-fold effect can be expressed as the convolution of the diffraction factor and the interference factor. Our conclusion could be helpful to understand the contribution of evanescent waves to the optical responses of sub-wavelength structures such as slits and grooves.     

细胞色素P450 2E1催化下乙醛羟基化反应动力学同位素效应的理论研究

采用建立在Eyring绝对反应速率理论基础上的计算模型,对细胞色素P4502E1催化下乙醛羟基化反应动力学同位素效应进行了理论研究.计算表明,乙醛羟基化反应的动力学同位素效应大小约为5.0(Wigner量子校正后约为7.0左右),远比烷烃羟基化反应的动力学同位素效应要小的多.这个反应对温度比较敏感,所以反应存在明显的量子隧穿现象.文中还对动力学同位素效应给出了相应的过渡态构型方面的解释.     

外开槽同轴波导大轨道回旋自谐振脉塞放大器

 运用大轨道电子束,对外开槽同轴波导回旋自谐振放大器进行了线性动力学理论分析和非线性自洽模型模拟。由线性动力学理论分析和非线性模拟得到的结果在线性增长部分吻合得很好。为了有效抑制绝对不稳定性,对电子束流的选择进行了讨论。计算结果表明：对于电压为700 kV, 电流为100 A, 电子束纵横向速度比为0.8的大轨道电子束, TE₅₁外开槽同轴波导回旋自谐振脉塞放大器的峰值功率和峰值效率分别可以达到6.27 MW和8.96%。     

Oxygen Plasma Technology-Assisted Preparation of Three-Dimensional Reduced Graphene Oxide/Polypyrrole/Strontium Composite Scaffold for Repair of Bone Defects Caused by Osteoporosis

Repairs of bone defects caused by osteoporosis have always relied on bone tissue engineering. However, the preparation of composite tissue engineering scaffolds with a three-dimensional (3D) macroporous structure poses huge challenges in achieving osteoconduction and osteoinduction for repairing bone defects caused by osteoporosis. In the current study, a three-dimensional macroporous (150–300 μm) reduced graphene oxide/polypyrrole composite scaffold modified by strontium (Sr) (3D rGO/PPY/Sr) was successfully prepared using the oxygen plasma technology-assisted method, which is simple, safe, and inexpensive. The findings of the MTT assay and AO/EB fluorescence double staining showed that 3D rGO/PPY/Sr has a good biocompatibility and effectively promoted MC3T3-E1 cell proliferation. Furthermore, the ALP assay and alizarin red staining showed that 3D rGO/PPY/Sr increased the expression levels of ALP activity and the formation of calcified nodules. The desirable biocompatibility, osteoconduction, and osteoinduction abilities, assure that the 3D macroporous rGO/PPY/Sr composite scaffold offers promising potential for use in the repair of bone defects caused by osteoporosis in bone tissue engineering.     

Synthesis of Caffeic Acid Sulphonamide Derivatives and Preliminary Exploration of Their Biological Applications

Structural modification of native compounds is an effective way to develop new drugs with increased pharmacological activities and improved material characteristics. In this study, caffeic acid sulphonamide derivatives(CSs) were synthesised by conjugating sulphonamides to the backbone of caffeic acid. The structures of these derivatives were elucidated by means of Fourier transform infrared spectroscopy(FTIR), ¹H NMR, ¹³C NMR, and electrospray ionization mass spectroscopy(ESI-MS). A content determination method was established by ultraviolet detection. The lipophilicity, 2,2-diphenyl-1-picrylhydrazy free radical(DPPH) scavenging capacity, anti-coagulant effects, anti-bacterial activity, cytotoxicity, in vitro anti-proliferative activity against tumour cells, and the ability of the compounds to promote the proliferation of chondrocytes were evaluated. The results indicate that CSs exhibit strong DPPH scavenging activity, high lipophilicity, good anti-coagulant activities, wide anti-bacterial activity range, low cytotoxicity, and an excellent ability to promote chondrocyte proliferation.     

核酸与抗癌药物的作用和广义荧光猝灭方程

通过荧光法在不同温度下研究了2种抗癌新药:吡柔比星和表柔比星与小牛胸腺DNA的作用,分别应用荧光猝灭和荧光加强理论公式计算了它们的结合常数等,进而分别计算了它们的热力学函数.首先,热力学研究结果表明核酸与药物作用属于氢键和/或Van der Waals力;其次,即使是核酸类生物大分子其与药物的作用,荧光猝灭和荧光加强公式的计算结果仍符合等效性规律;第三,本文对这些猝灭图、双倒数图、生成常数、和热力学数据的差异进行了综合分析比较,结果表明,基于荧光加强理论公式(4)获得的图谱和数值显示更为合理.因而我们建议,即使在研究受体-底物的荧光猝灭反应时,采用荧光加强理论公式(4)可以获得更符合实际的结果.结合以前的类似结果,我们指出:对于任何生物大分子和活性小分子(含金属离子)之间由给体-受体作用所导致的荧光猝灭和荧光加强效应,均可应用我们导出的荧光加强理论公式(4)进行处理,因此我们定名其为广义的荧光猝灭方程.     

Manipulating the Click Reactivity of Dibenzoazacyclooctynes: From Azide Click Component to Caged Acylation Reagent by Silver Catalysis

Strain-promoted azide–alkyne cycloaddition using dibenzoazacyclooctyne (DBCO) is widely applied in copper-free bioorthogonal reactions. Reported here is the efficient acid-promoted rearrangement and silver-catalyzed amidation of DBCO, which alters its click reactivity robustly. In the switched click reaction, DBCO, as a caged acylation reagent, enables rapid peptide/protein modification after decaging facilitated by silver catalysts, rendering site-specific conjugation of an IgG antibody by a Fc-targeting peptide.