Promising Chemotherapy for Malignant Pediatric Brain Tumor in Recent Biological Insights

Brain tumors are the most widespread malignancies in children around the world. Chemotherapy plays a critical role in the treatment of these tumors. Although the current chemotherapy process has a remarkable outcome for a certain subtype of brain tumor, improving patient survival is still a major challenge. Further intensive treatment with conventional non-specific chemotherapy could cause additional adverse reactions without significant advancement in survival. Recently, patient derived brain tumor, xenograft, and whole genome analysis using deep sequencing technology has made a significant contribution to our understanding of cancer treatment. This realization has changed the focus to new agents, targeting the molecular pathways that are critical to tumor survival or proliferation. Thus, many novel drugs targeting epigenetic regulators or tyrosine kinase have been developed. These selective drugs may have less toxicity in normal cells and are expected to be more effective than non-specific chemotherapeutics. This review will summarize the latest novel targets and corresponding candidate drugs, which are promising chemotherapy for brain tumors according to the biological insights.     

Rapid Detection of Five Estrogens Added Illegally to Dietary Supplements by Combining TLC with Raman Imaging Microscope

Estrogens added illegally to dietary supplements are hazardous to human health. Traditional detection and analysis methods have many limitations, and we have developed an assay that combines thin-layer chromatography with Raman imaging microscopy (TLC-RIM). The five estrogens (estrone, estradiol, estriol, ethinyl estradiol, and diethylstilbestrol) were initially separated by TLC, then detected by area scanning Raman imaging with a 532 nm laser under a microscope. Raman spectra were obtained for each estrogen, which were used for detecting estrogen illegally added to botanical dietary supplements. The LOD of each estrogen was 0.4, 1.0, 0.8, 0.2, and 0.2 mg/mL, respectively. The matrix in the real sample did not interfere with the detection of estrogens. The method was fast, sensitive, stable, specific, and reliable.     

Theoretical study of (e, 2e) triple differential cross sections of pyrimidine and tetrahydrofurfuryl alcohol molecules using multi-center distorted-wave method

We report theoretical studies of electron impact triple differential cross sections of two bio-molecules,pyrimidine and tetrahydrofurfuryl alcohol,in the coplanar asymmetric kinematic conditions with the impact energy of 250 eV and ejected electron energy of 20 eV at three scattering angles of-5°,-10°,and-15°.Present multi-center distorted-wave method well describes the experimental data,which was obtained by performing(e,2e)experiment.The calculations show that the secondary electron produced by the primary impact electron is strongly influenced by the molecular ionic multi-center potential,which must be considered when the low energy electron interacts with DNA analogues.     

1,4-bis[2-(4-pyridyl)ethenyl]-benzene衍生物热致变色研究

本文制备了三种在1,4-bis[2-(4-pyridyl)ethenyl]-benzene(bp-eb)上接枝不同烷基链长度的热致变色材料DC8、DC12、DC16. 在365 nm激发光下,随着温度升高,它们呈现出荧光颜色的改变,这种改变来自于晶体态与无定形态之间的转变. 此外,DC16也呈现出光致变色的性质. 通过差示扫描量热法测试得到的相转变温度高于实验过程中荧光颜色改变时的温度. 因此,这种变色行为来自于光与热共同作用的结果. 乙醇可以使粉末变回起始的晶体状态,从而使荧光颜色恢复,实现热致变色行为的可逆. 本研究对理解热致变色分子的结构-性质关系,指导热致变色分子设计具有重要意义.     

地黄梓醇和乙酰胆碱酯酶作用的分子动力学模拟

梓醇能有效的的改善阿茨海默尔症状,但与乙酰胆碱酯酶(Acetylcholinesterase,AchE)作用的分子机制尚不明晰.本文运用分子动力学模拟、结合自由能的计算和丙氨酸突变扫描的方法研究了两者的结合模式,结果表明:梓醇结合位点为乙酰胆碱酯酶的催化活性中心,并形成3个氢键,结合自由能为-60.59 k J/mol,结合的主要驱动力是范德华力和静电作用力,主要抑制力是极性溶剂化能,Tyr151和Gln176是两者结合的关键氨基酸.这些研究为开发高效的Ach E梓醇类似物抑制剂提供理论支持.     

Prospective study on observations of γ-ray sources in the Galaxy using the HADAR experiment

The High Altitude Detection of Astronomical Radiation (HADAR) experiment is a refracting terrestrial telescope array based on the atmospheric Cherenkov imaging technique. It focuses the Cherenkov light emitted by extensive air showers through a large aperture water-lens system for observing very-high-energy γ-rays and cosmic rays. With the advantages of a large field-of-view (FOV) and low energy threshold, the HADAR experiment operates in a large-scale sky scanning mode to observe galactic sources. This study presents the prospects of using the HADAR experiment for the sky survey of TeV γ-ray sources from TeVCat and provids a one-year survey of statistical significance. Results from the simulation show that a total of 23 galactic point sources, including five supernova remnant sources and superbubbles, four pulsar wind nebula sources, and 14 unidentified sources, were detected in the HADAR FOV with a significance greater than 5 standard deviations (σ). The statistical significance for the Crab Nebula during one year of operation reached 346.0 σ and the one-year integral sensitivity of HADAR above 1 TeV was ~1.3%–2.4% of the flux from the Crab Nebula.     

基于神光Ⅲ原型的激光直接驱动自由面准等熵实验研究

长脉冲激光打靶的直接驱动方式效率较高,但对激光强度变化非常敏感。利用测量自由面速度历史的方法对激光直接驱动准等熵压缩实验技术进行了分析,为改进激光直接驱动的准等熵压缩实验技术提供技术基础。介绍了国内在神光III原型装置上首次开展的激光直接驱动自由面准等熵压缩实验。对实验靶型、激光波形、典型实验结果以及实验中的关键技术进行了分析。在激光能量为1000 J的实验中,使用成像型速度干涉仪获得了较为理想的准等熵压缩条纹图。实验发现,自由面速度达到11.3 km/s时,自由面反射的探针光信号消失。通过对比Multi-1D软件的理论模拟数据与实验处理的结果,发现由于Al自由面缺少约束,这类实验会造成波系复杂化的问题,但是对主冲击的研究还是有意义的。对某些特殊材料,在很难找到阻抗匹配窗口的条件下,利用激光直接驱动方式研究材料高压响应特性提供了另一条可实施的技术途径。     

OX2(X=F，Cl，Br，I，At)中的离域π63键

本文在理论层面上研究了OX₂(X=F,Cl,Br,I,At)分子的电子结构,结果表明其中存在离域π⁶₃键,氧原子采取sp²杂化方式,与价层电子对互斥理论预测的结果不符. 提出了离域稳定化能衡量形成离域π⁶₃键对能量降低的贡献,证实离域π⁶₃键对分子结构起到了额外的稳定作用. 这些现象可以总结为一种配位效应.     

基序B参与调控模板依赖的聚合酶抑制作用

RNA依赖的RNA聚合酶是参与新冠病毒进行RNA复制与转录的主要分子机器. 之前的实验研究表明瑞德西韦在模板链上时存在两次抑制作用,即不仅可以抑制与之互补的尿嘧啶核苷三磷酸的加成,还可以抑制下一位核苷三磷酸的加成. 然而,第二次抑制作用的分子机制尚未阐明. 本文运用了分子动力学模拟,发现瑞德西韦在模板链上的第二次抑制不是直接作用于核苷酸在活性位点的加成,而是源于瑞德西韦从+1位点到-1位点的迁移过程受到阻碍,这将导致活性位点无法空出,核苷三磷酸无法进入活性位点从而产物链的延长被终止. 首先,发现了基序B中G683会和瑞德西韦的1''-氰基相互作用,导致移位后态的RNA双链配对稳定性低于移位前态,从而使得瑞德西韦的移位在热力学上不易发生. 其次,由于瑞德西韦的1''-氰基在迁移过程中会与基序B的S682产生位阻,进一步从动力学上阻碍了瑞德西韦动态移位的发生. 本研究不仅揭示了基序B上两个相邻且高度保守的氨基酸可以调控瑞德西韦沿模板链的移位过程,同时,本文的发现也进一步完善了对瑞德西韦抑制新冠病毒RNA复制和转录的分子机制的理解.     

Discrete Boltzmann Method with Maxwell-Type Boundary Condition for Slip Flow

The rarefied effect of gas flow in microchannel is significant and cannot be well described by traditional hydrodynamic models. It has been known that discrete Boltzmann model(DBM) has the potential to investigate flows in a relatively wider range of Knudsen number because of its intrinsic kinetic nature inherited from Boltzmann equation.It is crucial to have a proper kinetic boundary condition for DBM to capture the velocity slip and the flow characteristics in the Knudsen layer. In this paper, we present a DBM combined with Maxwell-type boundary condition model for slip flow. The tangential momentum accommodation coefficient is introduced to implement a gas-surface interaction model.Both the velocity slip and the Knudsen layer under various Knudsen numbers and accommodation coefficients can be well described. Two kinds of slip flows, including Couette flow and Poiseuille flow, are simulated to verify the model.To dynamically compare results from different models, the relation between the definition of Knudsen number in hard sphere model and that in BGK model is clarified.