PI3K/mTOR抑制剂的合成及生物活性

以NVP-BEZ235为先导化合物,设计合成了10个磷脂酰肌醇3-激酶/哺乳动物雷帕霉素靶蛋白(PI3K/mTOR)抑制剂;目标化合物的结构经核磁共振波谱(NMR)和液相色谱-质谱(LC-MS)分析确证.采用噻唑蓝(MTT)比色法在人急性单核细胞白血病细胞株(MV4-11)、人乳腺癌细胞株(BT474)和人前列腺癌细胞株(PC-3)中测定了目标化合物的抗肿瘤活性,并对其构效关系进行了初步的讨论.结果表明,化合物11(FP-189)对MV4-11细胞株表现出较强的抑制活性(IC_(50)=22.5 nmol/L),且具有良好的溶解性,可以作为白血病治疗的候选药物进行下一步开发.     

Transformation of ferrihydrite to goethite and then to maghemite in a mixed FeCl2/NaOH solution

Ferrihydrite (Fe₅O₇(OH)·4H₂O) is poorly crystalline hydrated ferric oxyhydroxide. Using a treatment in a mixed FeCl₂/NaOH solution, we attempted to prepare magnetic nanoscale particles from ferrihydrite. During the treatment, the concentration of FeCl₂ was fixed at 0.1 M, and the concentration of NaOH was varied from 0.09 to 0.26 M. The as-prepared products were characterized using X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometry. The experimental results showed that under the FeCl₂/NaOH solution treatment, the ferrihydrite transformed into nanoscale γ-Fe₂O₃ via an α-FeO(OH) intermediate phase. The as-prepared products contained rod-type α-FeO(OH), sphere-type γ-Fe₂O_3, and flake-type γ-Fe₂O₃ particles. A mechanism for a coupling of the aggregation and the transition was proposed to interpret the formation of highly crystalline nanoscale particles from the poorly crystalline smaller particles.     

The quasi-magnetic-hysteresis behavior of polydisperse ferrofluids with small coupling constant

The magnetization behaviors of ferrofluids based on γ-Fe₂O₃/Ni₂O₃ composite nanoparticles of size about 11 nm have been investigated. The dipole coupling constant λ of these particles is so small (0.43) that they cannot form aggregates through magnetic interaction alone. Experimental results have shown that for a polydisperse ferrofluid with a particle volume fraction of ?_V=2.4%, the magnetization curve exhibits quasi-magnetic-hysteresis behavior, i.e., the demagnetization curve lies above the magnetization curve in a high field. However, for a more dilute γ-Fe₂O₃/Ni₂O₃ ferrofluid with ?_V=0.94%, the magnetization curve does not show such behavior. According to the bidisperse model for polydisperse ferrofluids, these magnetization behaviors may be attributed to field-induced effects of self-assembled pre-existing chain-like aggregates. For such pre-existing chain-like aggregates, the orientation of the moments inside the particles is not co-linear, so that during the magnetization and demagnetization processes, their apparent magnetizations at the high-field limit are different. As a consequence, the magnetization curve of the ferrofluid with ?_V=2.4% displays quasi-magnetic-hysteresis.     

The modification of the initial susceptibility of dilute binary ferrofluids based on γ-Fe2O3/ZnFe2O4 nanoparticles

This paper presents a multi-band metamaterial absorber comprising three multi-gap split-ring resonators (SRRs) with different radii and ring widths, designed in combinatorial approach. Experiments demonstrate that it can perform absorption peaks at three resonant frequencies 7.10 GHz, 10.04 GHz, and 17.44 GHz with the absorption of 99.90%, 99.91%, and 99.68%, respectively. The physical mechanism of metamaterial absorber was explained through numerical calculation and simulation, which showed that three absorption peaks were caused respectively by the three four-gap SRRs. The absorber is insensitive to incident angles and polarization states, so it has broad prospect of application.     

Polydopamine Nanoparticle as a Multifunctional Nanocarrier for Combined Radiophotodynamic Therapy of Cancer

Combination of different therapeutic strategies to treat cancer has attracted tremendous attention in recent years. Herein, the authors develop polydopamine (PDA) nanoparticles with polyethylene glycol (PEG) modification as a multifunctional nanocarrier for coloading photosensitizer chlorine6 (Ce6) and curcumin (Cur) for combined photodynamic therapy (PDT) and radiotherapy (RT) of cancer. PEGylated PDA nanoparticles (PDA‐PEG) exhibit well water soluble and biocompatible in different physiological solutions and cause no obvious toxicity to cancer cells. In this nanoparticle, the loaded Ce6 can trigger the generation of single oxygen under near‐infrared laser irradiation for PDT, while the loaded Cur can act as an excellent radiosensitizer under X‐ray irradiation for enhanced external RT. As demonstrated by in vitro and in vivo therapeutic efficiency, combined PDT and RT based on PDA‐PEG/Cur/Ce6 nanoparticles exhibits significant inhibition the growth of cancer cells, revealing perfect performance in cancer treatment. Therefore, the study not only presents a polymer‐based theranostic platform for cancer treatment but also demonstrates the potential applications of combined RT and PDT for the future clinic cancer therapy.     

Total synthesis based modification of benzoquinone ansamycin antibiotics: C8 diversification of C5-C15 fragments

Benzoquinone ansamycins are known to be potent Heat shock protein (Hsp90) inhibitors, and total-synthesis-based structure modification of this natural product family may lead to the discovery of novel cancer chemotherapeutics. Described in this paper is a unified synthetic route that gives access to both natural and C-8-modified C5-C15 fragments of this natural product family.     

浙西洞穴气候特征及其分析

本文通过几年来对浙西洞穴气候考察资料的分析,揭示了该区不同类型洞穴各气象要素的时空分布特征及变化规律,并探讨了其形成原因.这为如何合理开发和科学利用洞穴资源以及洞穴气候的理论研究提供了一个实例.     

深亚微米激光光刻研究

报道用远紫外准分子激光进行亚微光刻的实验结果，以波长为２４８．３ｎｍ的ＫｒＦ准分子激光为光源，以光管均匀器为主构成照明系统，采用带有平行平板为像差样正板的１：１折反射投影光刻物镜，在两种光刻胶上分别获得了０．６μｍ和０．５μｍ的光刻分辨率。     

一种7-羟基四氢喹喔啉-6-甲醛衍生物对H2S的比色和荧光识别

本文利用1,4-二乙基-7-羟基四氢喹喔啉-6-甲醛与2-甲基苯并噻唑盐反应制备了荧光探针L,并对其结构进行了表征。实验结果表明,探针L在DMSO溶液中对H_2S具有快速荧光"关-开"响应以及高选择性和较好的抗干扰能力,检测限为2. 5×10~(-6)mol/L。在365nm紫外灯照射下,L的荧光颜色由无荧光变成黄绿色强荧光;此外,加入H_2S后探针L的DMSO溶液颜色由蓝紫色变为无色,通过裸眼即可识别H_2S。     

Cover Picture: Transition‐Metal‐Free Defluorosilylation of Fluoroalkenes with Silylboronates* (Chin. J. Chem. 10/2019)

The cover picture shows a simple, inexpensive and robust method on defluorosilylation of diverse fluoroalkenes with silylboronates in the presence of alkoxy base to directly synthesize various silylated fluoroalkenes. Density functional theory calculations revealed that transient silyl anion complex undergoes S_N2’ or S_N^V substitution, which is responsible for this base‐mediated defluorosilylation reaction, thus obviating the need for copper salts. More details are discussed in the article by Shi et al. on page 1009–1014.