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61.
A. E. Bañuelos-Hernández J. A. Mendoza-Espinoza 《Russian Journal of General Chemistry》2014,84(7):1450-1457
The carbohydrate compounds have interesting stereochemical properties and can be used as chiral building blocks in the production of more complex derivatives. L-Rhamnose has been reported to participate in the synthesis of cytotoxic α-pyrones owing to the stereochemistry of the hydroxy groups. To study the conformational properties of acetyl derivatives of L-rhamnose, it was tosylated with the subsequent reduction and acetylation. These series of reactions produced an interesting mixture of poly-acetylated compounds. The mixture was separated by HPLC, characterized by 1D and 2D NMR techniques and compared with models obtained on DFT/B3LYP/DGDZVP theory level of calculation, taking into account the effect of pyridine as solvent in the transformation of this carbohydrate. The results show a mixture of three pyranoside products with tosyl group in positions 2, 3, and 4. These latter compounds after reduction with aluminum hydride and acetylation yielded two main products, one triacetate pyranoside and an open-chain mannositol tretraacetate. 相似文献
62.
Yoldas Seki Aylin Altinisik Başak Demircioğlu Caner Tetik 《Cellulose (London, England)》2014,21(3):1689-1698
A novel carboxymethylcellulose (CMC)–hydroxyethylcellulose (HEC)-based hydrogel with sensitivity to environmental changes, pH and salts was synthesized by using fumaric acid and malic acid at various concentrations. Water uptake capacity of hydrogels was investigated in distilled water, various salt and pH solutions. From pH-dependent studies, it was found that greater water uptake values were observed at greater pH values (7.4), and reversible pH responsiveness of CMC–HEC based hydrogels was obtained. Decreasing the water uptake capacity with increasing of the charge of the metal cation (Al3+ < Ca2+ < Na+) demonstrated metal ion responsiveness of CMC–HEC-based hydrogels. From tensile tests of the hydrogels, a greater crosslinker concentration led to greater tensile strength values. Thermogravimetric analysis and scanning electron microscopy images were used to determine the thermal stability and to observe morphological properties of the samples, respectively. 相似文献
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Xiao-Xu Ba Tian Gao Mian Yang Peng Jiang Feng-Lei Jiang Yi Liu 《Journal of solution chemistry》2020,49(1):100-116
As one of the newly emerged nanomaterials, graphene quantum dots (GQDs) have shown great application potential as tracking probes and drug carriers in biological areas. The GQDs synthesized via the nitric acid reflux method in this study turned out to quench the fluorescence of human serum albumin (HSA) and gamma globulin (γ-globulin) in two different functional ways. The fluorescence quenching effect of GQDs on HSA is a static pattern and the predominant interaction forces are hydrogen bonds and van der Waals forces. Distinct from HSA, the interaction between GQDs and γ-globulins belongs to dynamic quenching and is driven by electrostatic forces. Ultraviolet–visible (UV–vis) differential spectrometry and transient state fluorescence spectrometry were also utilized to further confirm their quenching types. Also, thermodynamics parameters, the enthalpy change (ΔH) and entropy change (ΔS) of reaction between GQDs and proteins were obtained through a series of calculations from the van’t Hoff equation. Furthermore, the effect of GQDs on the conformational structure of proteins was characterized by synchronous fluorescence spectra (SFS), three-dimensional (3D) fluorescence and circular dichroism (CD) spectra. In addition, the binding mechanism of GQDs with HSA and γ-globulins were proposed based on the obtained experimental results. The research on the reaction between GQDs with HSA and γ-globulins offers promising insight for the further application of nanomaterials in biomedical fields. 相似文献
65.
利用扫描电子显微镜(SEM)和X射线能谱仪(EDS)对聚丙烯/聚氯乙烯(PP80/PVC20)二元体系,以及聚丙烯多单体接枝物[PP-g-(St-co-MMA)]/PP/PVC三元体系的相容性进行了研究。由X射线能谱微区分析得到了共混物中氯元素面分布图。对氯元素面分布进行了粒径分布统计和面积计算。实验结果表明:在PP80/PVC20共混物100份中加入6份PP-g-(St-co-MMA)增容剂时,增容效果最好;进一步增加PP-g-(St-co-MMA)含量时,PP/PVC的相容性反而降低。差示扫描量热仪(DSC)的实验结果也佐证了SEM和EDS的实验结果。 相似文献
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Fluorescent Coumarin–Artemisinin Conjugates as Mitochondria‐Targeting Theranostic Probes for Enhanced Anticancer Activities 下载免费PDF全文
Dr. Xu Zhang Qian Ba Zhanni Gu Dr. Diliang Guo Prof. Yu Zhou Prof. Yungen Xu Prof. Hui Wang Prof. Deju Ye Prof. Hong Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17415-17421
Mitochondria‐targeting theranostic probes that enable the simultaneously reporting of and triggering of mitochondrial dysfunctions in cancer cells are highly attractive for cancer diagnosis and therapy. Three fluorescent mitochondria‐targeting theranostic probes have been developed by linking a mitochondrial dye, coumarin‐3‐carboximide, with a widely used traditional Chinese medicine, artemisinin, to kill cancer cells. Fluorescence images showed that the designed coumarin–artemisinin conjugates localized mainly in mitochondria, leading to enhanced anticancer activities over artemisinin. High cytotoxicity against cancer cells correlated with the strong ability to accumulate in mitochondria, which could efficiently increase the intracellular reactive oxygen species level and induce cell apoptosis. This study highlights the potential of using mitochondria‐targeting fluorophores to selectively trigger and directly visualize subcellular drug delivery in living cells. 相似文献
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A novel nitridogallate fluoride LiBa5GaN3F5 – Synthesis,crystal structure,and band gap determination
LiBa5GaN3F5 was obtained as red crystals by reaction of Ba, Ga, NaN3 and EuF3 in a Na/Li flux at 760 °C in weld-shut tantalum crucibles. The crystal structure (Pnma (no. 62), a = 15.456(3), b = 5.707(1), c = 12.259(3) Å, Z = 4) was solved on the basis of single-crystal X-ray diffraction data. In the solid there are trigonal planar [GaN3]6? ions and zigzag chains of vertex sharing LiF6 octahedrons surrounded by Ba2+ ions. Optical measurements and calculations of the electronic structure revealed a band gap of ≤1.9 eV. According to the calculations, the observed transition occurs from a nitrogen state into a hybrid Ba/N state. 相似文献