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1.
Heparanase (Hpse) is an endo-β-D-glucuronidase capable of cleaving heparan sulfate side chains. Its upregulated expression is implicated in tumor growth, metastasis and angiogenesis, thus making it an attractive target in cancer therapeutics. Currently, a few small molecule inhibitors have been reported to inhibit Hpse, with promising oral administration and pharmacokinetic (PK) properties. In the present study, a ligand-based pharmacophore model was generated from a dataset of well-known active small molecule Hpse inhibitors which were observed to display favorable PK properties. The compounds from the InterBioScreen database of natural (69,034) and synthetic (195,469) molecules were first filtered for their drug-likeness and the pharmacophore model was used to screen the drug-like database. The compounds acquired from screening were subjected to molecular docking with Heparanase, where two molecules used in pharmacophore generation were used as reference. From the docking analysis, 33 compounds displayed higher docking scores than the reference and favorable interactions with the catalytic residues. Complex interactions were further evaluated by molecular dynamics simulations to assess their stability over a period of 50 ns. Furthermore, the binding free energies of the 33 compounds revealed 2 natural and 2 synthetic compounds, with better binding affinities than reference molecules, and were, therefore, deemed as hits. The hit compounds presented from this in silico investigation could act as potent Heparanase inhibitors and further serve as lead scaffolds to develop compounds targeting Heparanase upregulation in cancer.  相似文献   
2.
阿尔兹海默病的疾病进展模型与研究进展   总被引:1,自引:0,他引:1  
阿尔兹海默病(AD)是一种病理机制暂不明确的神经退行性疾病,定量药理学中的疾病进展模型可以通过定量的方法充分描述AD患者疾病发展轨迹。通过模型中引入生物标志物信息,可有助于加深对AD病理机制的研究,辅助并优化临床试验的设计。现已有多种经验性或半机制的AD疾病进展模型报道。本文对此进行了综述,以期为阿尔兹海默病的临床研究和新药研发提供参考。  相似文献   
3.
4.
分析了混合型有源滤波器HAPF(hybrid active power filter)在高压直流系统应用时的稳定性问题,其中HAPF采用H桥级联变换器与LC滤波器组合的方案,对高压直流系统的特征谐波电流进行滤波。为了分析在电网阻抗变化时HAPF出现的谐波谐振现象,对HAPF进行了阻抗建模,基于阻抗模型的分析结果,采用了具有延时补偿功能的谐振调节器对阻抗特性进行修正,并从提高稳定性角度提出了相应的控制参数设计方法。阻抗模型分析结果表明,控制系统延时产生的负阻尼是引发稳定性问题的主要原因,采用改进后的控制方法可以将延时产生的负阻尼修正为正阻尼,能够有效避免谐波谐振。在PSCAD中进行仿真建模,并通过阻抗扫描验证了有源滤波器的阻抗特性。仿真案例证实了控制方法的有效性。  相似文献   
5.
Perfluorosulfonic acid ionomer membranes have been widely used as proton conducting membranes in various electrochemical processes such as polymer electrolyte fuel cells and water electrolysis. While their thermal stability has been studied by thermogravimetry and analysis of low molecular weight products, their decomposition mechanism is little understood. In this study a newly developed methodology of thermal desorption and pyrolysis in combination with direct analysis in real time mass spectrometry is applied for Nafion membrane. An ambient ionization source and a high-resolution time-of-flight mass spectrometer enabled unambiguous assignment of gaseous products. Thermal decomposition is initiated by side chain detachment above 350°C, which leaves carbonyls on the main chain at the locations of the side chains. Perfluoroalkanes are released above 400°C by main chain scission and their further decomposition products dominate above 500 °C. DFT calculation of reaction energies and barrier heights of model compounds support proposed decomposition reactions.  相似文献   
6.
Nepheline precipitation in nuclear waste glasses during vitrification can be detrimental due to the negative effect on chemical durability often associated with its formation. Developing models to accurately predict nepheline precipitation from compositions is important for increasing waste loading since existing models can be overly conservative. In this study, an expanded dataset of 955 glasses, including 352 high-level waste glasses, was compiled from literature data. Previously developed submixture models were refitted using the new dataset, where a misclassification rate of 7.8% was achieved. In addition, nine machine learning (ML) algorithms (k-nearest neighbor, Gaussian process regression, artificial neural network, support vector machine, decision tree, etc.) were applied to evaluate their ability to predict nepheline precipitation from glass compositions. Model accuracy, precision, recall/sensitivity, and F1 scores were systemically compared between different ML algorithms and modeling protocols. Model prediction with an accuracy of ~0.9 (misclassification rate of ~10%) was observed for different algorithms under certain protocols. This study evaluated various ML models to predict nepheline precipitation in waste glasses, highlighting the importance of data preparation and modeling protocol, and their effect on model stability and reproducibility. The results provide insights into applying ML to predict glass properties and suggest areas for future research on modeling nepheline precipitation.  相似文献   
7.
建立了一种R1233zd(E)卧式冷凝器的动态仿真模型,其相比于稳态模型在预测系统运行特性方面具有明显优势。详细介绍了建模所用控制方程、离散方法、运算逻辑等,模型可以计算出冷凝器在每一时间步长下,每一个控制体内制冷剂、管壁、冷却水的状态参数。由于模型涵盖了换热管的几何参数,因此改变几何参数可以模拟采用不同换热管结构对冷凝器性能的影响,比较了采用不同齿距的换热管对换热器内部相区分布、换热量、出水温度的影响。模拟结果得出,采用齿距为1.3 mm的低肋管时,出水温度较光管提升1.5℃以上,达到稳定输出的时间提前1 min以上,换热量提升2.3倍。R1233zd(E)作为新型环保工质,缺乏相关的热泵模型研究,因此搭建该冷凝器模型是完成R1233zd(E)高温热泵模型的重要基础。  相似文献   
8.
利用FTIR、XRD研究了抚顺油页岩(OS)的组成结构,TG⁃MS分析了过渡金属盐催化剂(页岩灰作为载体负载NiCl2•6H2O、CuCl2•2H2O、ZnCl2)对OS热解的催化作用和挥发分析出的影响规律,采用Coats⁃Redfern模型分析过渡金属盐催化剂对OS热解活化能的影响。结果表明,OS中矿物质主要由石英、硅铝酸盐和少量的碳酸盐组成,有机质主要是脂肪族化合物。三种过渡金属盐催化剂对OS热解均有促进作用,且OS单独热解时,在390.1~581.8 ℃快速热解,占总失重的76.19%。动力学分析结果表明,过渡金属盐催化剂能降低OS热解所需的活化能,其中NiCl2•6H2O降低OS热解活化能的能力最高(18.7 kJ/mol),比OS单独热解活化能降低了23.55%。过渡金属盐催化剂的催化活性由高到低排序为NiCl2•6H2O>CuCl2•2H2O>ZnCl2。此外,过渡金属盐催化剂还能促使OS热解发生挥发分的裂化、芳构化和焦化等反应,从而提高挥发分中脂肪烃(以烷烃、烯烃为代表)和芳香烃浓度。  相似文献   
9.
In this study, laser surface treatment was applied to alter the surface texturing and chemical compositions of fused deposition modeling (FDM)-printed PEEK/CF samples to improve the deficiency of inert surface of PEEK as adherend substrate. The influence of IR-laser parameters including treatment gaps, single pulse energy and pulse widths on surface properties and shear bond strength were discussed. The results indicated that surface roughness was enhanced with decreasing treatment gap or increasing pulse energy, which reached the highest value of Ra = 32.44 μm at 0.4*0.4 mm2 treatment gap and 300 mJ single pulse energy. By adjusting laser pulse width, surface wettability changed from hydrophobicity to hydrophilicity. After micro-second laser ablation, the texturing structure was changed and acted as mechanical interlocking effect, and therefore make the shear bond strengths improve from 3.28 to 6.42 MPa compared with the untreated groups. On the other hand, functional groups on substrate surface were activated after nano-second laser ablation, which contributes to an enhancement of shear bond strength through chemical interaction between adhesives and substrates. Therefore, our work highlights an efficient method of laser surface treatment on the adhesion property of FDM-printed substrates.  相似文献   
10.
With liquefied natural gas becoming increasingly prevalent as a flexible source of energy, the design and optimization of industrial refrigeration cycles becomes even more important. In this article, we propose an integrated surrogate modeling and optimization framework to model and optimize the complex CryoMan Cascade refrigeration cycle. Dimensionality reduction techniques are used to reduce the large number of process decision variables which are subsequently supplied to an array of Gaussian processes, modeling both the process objective as well as feasibility constraints. Through iterative resampling of the rigorous model, this data-driven surrogate is continually refined and subsequently optimized. This approach was not only able to improve on the results of directly optimizing the process flow sheet but also located the set of optimal operating conditions in only 2 h as opposed to the original 3 weeks, facilitating its use in the operational optimization and enhanced process design of large-scale industrial chemical systems.  相似文献   
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