Low‐Temperature Synthesis of Thermoresponsive Diblock Copolymer Nano‐Objects via Aqueous Photoinitiated Polymerization‐Induced Self‐Assembly (Photo‐PISA) using Thermoresponsive Macro‐RAFT Agents

Photoinitiated reversible addition‐fragmentation chain transfer (RAFT) dispersion polymerization of 2‐hydroxypropyl methacrylate is conducted in water at low temperature using thermoresponsive copolymers of 2‐(2‐methoxyethoxy) ethyl methacrylate and oligo(ethylene glycol) methacrylate (M_n = 475 g mol⁻¹) as the macro‐RAFT agent. Kinetic studies confirm that quantitative monomer conversion is achieved within 15 min of visible‐light irradiation (405 nm, 0.5 mW cm⁻²), and good control is maintained during the polymerization. The polymerization can be temporally controlled by a simple “ON/OFF” switch of the light source. Finally, thermoresponsive diblock copolymer nano‐objects with a diverse set of complex morphologies (spheres, worms, and vesicles) are prepared using this particular formulation.

     

Thermal analysis of beamline heat load components due to increased power delivery from EAST neutral beam injector

Journal of Thermal Analysis and Calorimetry - According to EAST’s experimental plan, the long-pulse and high-power operation of neutral beam injector is the requirement for EAST. In this...     

质子辐照ZnO白漆光学退化的慢正电子湮没分析

 采用慢正电子湮没光谱研究低能质子辐照下ZnO白漆的光学退化。研究结果表明,随质子辐照注量的增加, 多普勒展宽谱的S参数逐渐减小,W参数逐渐增大。质子辐照下S-W参数拟合曲线的斜率发生改变。S参数的减小可以归结为锌空位含量的减少以及准正电子素的形成。准正电子素{单电离氧空位（捕获一个电子）+正电子}的形成,能够降低正电子湮没的速率,导致S参数减小。S参数的减小证实了质子辐照导致ZnO白漆中单电离氧空位数量的增加。S-W参数拟合曲线斜率的变化可以归结于质子辐照下双电离氧空位向单电离氧空位的转变。     

利用密度反馈实现离子源长脉冲放电

 介绍了等离子体密度对离子源放电的影响,为了获得长脉冲放电,采用朗缪尔探针测量等离子体密度并反馈调节离子源放电。基于朗缪尔探针测量,设计了控制部分硬件与软件构架,建立了离子源等离子体密度反馈控制系统,并成功地应用于离子源等离子体放电实验,通过反馈调节实验进气,得到了长达4.5 s的长脉冲放电,为中性束注入稳态运行提供了依据。     

Optical Properties and Radiation Stability of Al2O3 Microparticles,Nanoparticles and Microspheres

Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques - A comparative analysis of the diffuse reflectance spectra in the range from 200 to 2500 nm is carried out on...     

Proton and electron irradiation induced changes in the optical properties of ZnO pigments modified with ZrO2 and Al2O3 nanopowders

The effect of the modification of ZnO powders by ZrO₂ and Al₂O₃ nanoparticles with a concentration of 1–30 wt % is investigated by diffuse reflectance spectra within the wavelength range 0.2 to 2.5 μm before and after 100 keV proton and electron irradiation. It has been established that the introduction of nanoparticles enhances the optical stability of the pigments under proton irradiation, but reduces it under electron irradiation. Samples modified by 5 wt % of ZrO₂ nanoparticles have the highest stability of optical properties after proton exposure. The degradation of optical properties under electron irradiation is not high for this concentration of nanoparticles. A decrease in the absorption of pigments modified with nanoparticles after proton exposure is determined by a decrease in the intensity of bands located in the UV and visible regions. After electron exposure the absorption bands have a high intensity in the whole spectrum range.     

Photoluminescence of zinc oxide modified by nanopowders

The modifying effect of Al₂O₃, Al₂O₃ · CeO₂, ZrO₂, ZrO₂ · Y₂O₃ nanopowders on the photoluminescence spectra of ZnO powder in the 360–660 nm range is investigated. It is found that the introduction of nanoparticles causes a decrease in the ultraviolet band intensity and an increase in the visual spectral band intensity. The change in the intensity of elementary components of the visible range band during modification seems to be explained by the emergence of oxygen and zinc vacancies (V _O⁺ and V _Zn⁻) and interstitial oxygen ions (O _i ⁻).     

卤素对核酸类药物的修饰与影响研究进展

药物分子中引入卤素具有改善药物脂溶性、影响药物分子的电荷分布及影响药物的作用时间等特点,故被广泛应用。 作为抗病毒、抗肿瘤、干扰素诱导和免疫增强的、具有特定碱基序列的核酸药物也不例外。 本文综述了卤素对核酸结构中的嘧啶类、嘌呤类和核糖结构修饰后的核酸类药物生物活性产生的影响,以期为核酸及核酸类似物的药物研发提供新的思路。     

用回归分析方法优选有杆泵抽油井的抽汲参数

姚春冬，张树江．用回归分析方法优选有杆泵抽油井的抽汲参数，数理统计与管理，１９９７，１６（１），９～１５．本文根据现场测试数据，建立了抽油机井地面效率、井下功率损失与排量系数的回归公式，以此为基础建立了以系统效率为目标函数的抽油机井抽汲参数优化设计模型，从而提出了一种优选抽油机井抽汲参数的新方法     

Probing the role of metal cations on the aggregation behavior of amyloid β-peptide at a single molecule level by AFM

With the development of nanotechnology, understanding of intermolecular interactions on a single molecule level by atomic force spectroscopy (AFM) has played an important role in molecular biology and biomedical science. In recent years, some research suggested that the presence of metal cations is an important regulator in the processes of misfolding and aggregation of the amyloid β-protein (Aβ), which may be an important etiological factor of Alzheimer’s disease. However, the knowledge on the principle of interactions between Aβ and metal cations at the single molecule level is still poor understood. In this paper, the amyloid β-protein (Aβ) was fabricated on substrate of mixed thiol-modified gold nanoparticles using self-assembled monolayer method and the adhesion force in the longitudinal direction between metal cations and Aβ42 were investigated by AFM. The role of metal ions on Aβ aggregation is discussed from the perspective of single molecular force. The force results showed that the specific adhesion force F _i and the nonspecific force F ₀ between a single Aβ–Aβ pair in control experiment were calculated as 42 ± 3 and 80 pN, respectively. However, F _i between a single Aβ–Aβ pair in the presence of Cu²⁺, Zn²⁺, Ca²⁺ and Al³⁺ increased dramatically to 84 ± 6, 89 ± 3, 73 ± 5, 95 ± 5 pN successively, which indicated that unbinding between Aβ proteins is accelerated in the presence of metal cations. What is more, the imaging results showed that substoichiometric copper cations accelerate the formation of fibrils within 3 days. The combined atomic force spectroscopy and imaging analysis indicate that metal cations play a role in promoting the aggregating behavior of Aβ42.