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851.
Ju Hyup Lee 《Journal of Dispersion Science and Technology》2014,35(12):1801-1808
Cinnamoyl Pluronic F127 (CP F127) was prepared by reacting cinnamoyl chloride and Pluronic F127. On the 1H NMR spectrum of CP F127, 1.2 moiety of cinnamoyl group was found to be attached to one molecule of CP F127. Using pyrene as a fluorescence probe, it was found that not only Pluronic F127 but also CP F127 could be readily assembled into micelles, and the critical micelle concentration was around 0.015 mg/ml and 0.03 mg/ml, respectively. Pluronic F127 in aqueous solution (2% w/v) could form no particles in 10–20°C, but particles (ca. 30 nm in diameter) were detected on a dynamic light scattering machine in 25–40°C possibly due to the thermal micellization. However, CP F127 was assembled into particles (ca. 230 nm) even in the lower temperature range, possibly because of the intermolecular hydrophobic interaction of the cinnamoyl group. The particle size of CP F127 strongly depended on the medium temperature and UV irradiation time. CP F127 was a good emulsifier for the preparation of O/W emulsions. The oil droplet size markedly increased upon UV irradiation (254 nm, 6 W), possibly because of the photo-dimerization of cinnamoyl group, but it was little affected by the temperature change (10–40°C). 相似文献
852.
磁共振成像(MRI)是一种强大的非侵入式生物医学诊断技术. 临床上, MRI需要借助造影剂来提高成像质量, 从而提高诊断的准确性. 由于具有优越的信号放大能力和生物相容性, 自组装多肽探针可负载特定的MRI分子, 通过酶促自组装过程实现肿瘤靶向和特异性富集, 增强肿瘤病灶区MRI信号, 从而进一步提高MRI的准确性和灵敏度. 本综述总结了近年来多肽自组装探针在不同MRI模式( 1H MRI, 19F MRI和双自旋核MRI)下的最新进展, 并展望了这类新型探针在MRI领域的应用前景. 相似文献
853.
活性氧簇(ROS), 如过氧化氢, 在生物体内的各种生理和病理过程中发挥着重要作用. 生物体内活性氧簇水平的异常与多种疾病(炎症、 肿瘤和器官损伤等)密切相关, 使ROS监测成为研究和诊断这些疾病的重要工具. 目前, 实现活体内深组织中的活性氧簇成像仍然面临挑战. 本文设计并合成了一种响应型的19F磁共振成像(MRI)探针(Gd-DPBF), 并将其用于实现对活体内通用活性氧簇的检测和成像. 该探针由钆螯合物通过活性氧簇响应的芳香硼酸酯键与含氟砌块相连接构成. 体外和体内成像实验结果证实, 该探针可以实现在活体荷瘤小鼠中针对肿瘤中高表达的活性氧进行检测和成像, 展示了其在生物体内对活性氧簇相关生理过程进行深组织、 零生物背景成像方面的潜力. 相似文献
854.
Sebastian Scheidel Laurina Östreicher Isabelle Mark Ann-Christin Pöppler 《Magnetic resonance in chemistry : MRC》2022,60(6):572-582
Although solid-state nuclear magnetic resonance (NMR) is a versatile analytical tool to study polymorphs and phase transitions of pharmaceutical molecules and products, this work summarizes examples of spontaneous and unexpected (and unwanted) structural rearrangements and phase transitions (amorphous-to-crystalline and crystalline-to-crystalline) under magic angle spinning (MAS) conditions, some of them clearly being due to the pressure experienced by the samples. It is widely known that such changes can often be detected by X-ray powder diffraction (XRPD); here, the capability of solid-state NMR experiments with a special focus on 1H-13C frequency-switched Lee–Goldburg heteronuclear correlation (FSLG HETCOR)/MAS NMR experiments to detect even subtle changes on a molecular level not observable by conventional 1D NMR experiments or XRPD is presented. Furthermore, it is shown that a polymorphic impurity combined with MAS can induce a crystalline-to-crystalline phase transition. This showcases that solid-state NMR is not always noninvasive and such changes upon MAS should be considered in particular when compounds are studied over longer time spans. 相似文献
855.
Pan Wang Dr. Jian-Wei Wang Prof. Wen-Hua Zhang Dr. Hongzhen Bai Prof. Guping Tang Prof. David J. Young 《化学:亚洲杂志》2021,16(19):2993-3000
Nanoformulations of mononuclear Pt complexes cis-PtCl2(PPh3)2 ( 1 ), [Pt(PPh3)2(L−Cys)] ⋅ H2O ( 3 , L−Cys=L-cysteinate), trans-PtCl2(PPh2PhNMe2)2 ( 4 ; PPh2PhNMe2=4-(dimethylamine)triphenylphosphine), trans-PtI2(PPh2PhNMe2)2 ( 5 ) and dinuclear Pt cluster Pt2(μ-S)2(PPh3)4 ( 2 ) have comparable cytotoxicity to cisplatin against murine melanoma cell line B16F10. Masking of these discrete molecular entities within the hydrophobic core of Pluronic® F-127 significantly boosted their solubility and stability, ensuring efficient cellular uptake, giving in vitro IC50 values in the range of 0.87–11.23 μM. These results highlight the potential therapeutic value of Pt complexes featuring stable Pt−P bonds in nanocomposite formulations with biocompatible amphiphilic polymers. 相似文献
856.
We investigate the multifractal properties of price increments in the cases of derivative and spot markets. Through the multifractal detrended fluctuation analysis, we estimate the generalized Hurst and the Renyi exponents for price fluctuations. By deriving the singularity spectrum from the above exponents, we quantify the multifractality of a financial time series and compare the multifractal properties of two different markets. The different behavior of each agent-group in transactions is also discussed. In order to identify the nature of the underlying multifractality, we apply the method of surrogate data to both sets of financial data. It is shown that multifractality due to a fat-tailed distribution is significant. 相似文献
857.
Ebrahimi-Fard Kurusch José M. Gracia-Bondía Frédéric Patras 《Letters in Mathematical Physics》2007,81(1):61-75
The word problem for an arbitrary associative Rota–Baxter algebra is solved. This leads to a noncommutative generalization
of the classical Spitzer identities. Links to other combinatorial aspects are indicated.
相似文献
858.
859.
针对常规分立双积分AD只能处理单端信号的问题,给出了一种输入和基准电压均支持差分信号的分立差分双积分AD。在热电阻测量中,把热电阻和基准电阻串联同一回路,以基准电阻压降作为基准,对热电阻的压降进行测量,并从软硬件两个方面对常见的误差因素进行对消处理。实验表明,该电路用于PT100测温时,跳字不超过0.1℃,精度可以达到±0.1℃,且对运放型号无特殊要求,是一种低成本、高精度的温度测量方案。 相似文献
860.
We extend the result of Lavrentiev which asserts that the harmonic measure and the arc-length measure are A∞ equivalent in a chord-arc Jordan domain. By using this result we extend the classical result of Lindelöf to the class of quasiconformal (q.c.) harmonic mappings by proving the following assertion. Assume that f is a quasiconformal harmonic mapping of the unit disk U onto a Jordan domain. Then the function A(z)=arg?(∂φ(f(z))/z) where z=reiφ, is well-defined and smooth in U?={z:0<|z|<1} and has a continuous extension to the boundary of the unit disk if and only if the image domain has C1 boundary. 相似文献