Identification of new dual spleen tyrosine kinase (Syk) and phosphoionositide-3-kinase δ (PI3Kδ) inhibitors using ligand and structure-based integrated ideal pharmacophore models

Owing to the complex pathophysiology of autoimmune disorders, it is very challenging to develop successful treatment strategies. Single-target agents are not desired therapeutics for such multi-factorial disorders. Considering the current need for the treatment of complex autoimmune disorders, dual inhibitors of Syk and PI3Kδ have been designed using ligand and structure-based molecular modelling strategies. In the present work, structure and ligand-based pharmacophore modelling was implemented for a varied set of Syk and PI3Kδ inhibitors. Ligand-based pharmacophore models (LBPMs) were developed for two kinases: ADPR.14 (r²_train = 0.809) for Syk, comprising one hydrogen bond acceptor, one hydrogen bond donor, one positive ionisable and one ring aromatic feature, and for PI3Kδ: AAARR.45 (r²_train = 0.942) consisting of three hydrogen bond acceptor and two ring aromatic features. The generated e-pharmacophore models revealed an additional ring aromatic and hydrophobic feature important for Syk and PI3Kδ inhibition, respectively. Subsequently, LBPMs were modified resulting in APDRR.14 hypothesis for Syk inhibitors and AAAHRR.45 hypothesis for PI3Kδ inhibitors employed for virtual screening. Thus, the combination of ligand and structure-based pharmacophore modelling helped in developing ideal pharmacophore models that may be an efficient tool for the designing of novel dual inhibitors of Syk and PI3Kδ.     

一种高活性 Ni掺杂 La0.6Sr0.4FeO3-δ作为碳基燃料固体氧化物燃料电池对称电极

固体氧化物燃料电池(SOFCs)是一种在中高温下可以直接将储存在燃料中的化学能转换成电能的全固态电化学反应装置.因其具有能量转换效率高、环境友好、全固态结构以及可以使用碳氢化合物燃料等优点,近年来受到了广泛的关注.在诸多电极材料当中, Ni基金属陶瓷是 SOFCs中最常使用的阳极材料,这是由于金属 Ni具有优良的电子电导和催化性能.然而当使用碳基化合物燃料时,传统的 Ni金属陶瓷阳极材料面临严重的积碳、Ni颗粒长大以及硫中毒等问题.这些问题不仅会影响 SOFCs的寿命,而且还会严重地降低 SOFC的商业化进程.因此,开发具有高催化活性、抗积碳的阳极材料对碳氢化合物为燃料的固体氧化物燃料电池的发展至关重要.与金属基阳极相比,氧化物阳极的热膨胀系数与电解质材料更匹配,性能的可调控性更强.铁酸锶镧(LSF)是一种分子式为 ABO3的钙钛矿结构的氧化物,在高温下具有较高的电子电导率.据报道 LSF作为阴极材料时,表现出了良好的性能.但是 LSF作为阳极材料时,却存在着催化性能不足的问题.我们研究了 Ni掺杂的 La0.6Sr0.4FeO3-δ(LSFN),以提高其作为 SOFCs阳极材料的催化性能.同时采用将 LSFN在 SOFC工作气氛下原位还原的方法,在 LSFN颗粒表面原位生长出分布均匀的纳米颗粒.透射电镜分析结果表明该偏析的颗粒为 Ni-Fe合金.有报道显示, Ni-Fe合金对碳氢化合物氧化具有良好的催化活性,所以在 LSFN颗粒表面生成这种合金颗粒有利于提高阳极材料的催化活性.对于 Ni-Fe合金以均匀的纳米颗粒析出的原因,还有待进一步研究.为了研究 LSFN作为 SOFC电极材料的性能,我们采用浸渍法将 LSFN前驱体溶液浸渍到氧化钇稳定氧化锆(YSZ)一体化电池的对称多孔骨架中,经过焙烧,得到了具有对称结构的 SOFC单电池.所使用的 YSZ一体化骨架为中间层薄而致密,两边厚而多孔的三层结构,这种结构可以显著地降低电解质的厚度,从而达到降低单电池的阻抗的目的.这一新型对称电池结构具有如下优点：阳极表面上可能发生的硫毒化和积碳问题有可能通过将阳极和阴极反用而消除;氧化剂(空气)将冲走吸附在电极上的硫和碳粒子,从而使电极得以再生.此外,氧化还原稳定的阴极预期将提高阴极的寿命.对单电池的电化学测试结果表明, LSFN电极材料的最佳浸渍量为30 wt%,这是因为较低的 LSFN浸渍量(<30 wt%),不能形成连续的电子传导网络,电极的电子传导能力不足;而 LSFN电极材料的浸渍量高于30 wt%时则会降低电极反应的三相界面,从而影响电池的性能.在750oC下, LSFN为电极的单电池在以湿润 C3H8为燃料时其开路电压(OCV)达到了约1.18 V,高于以 H2为燃料电池的电压.以 CH4为燃料时, LSFN为电极的单电池的开路电压远高于 LSF为电极的单电池.在750oC下,以 C3H8为燃料时, LSFN和 LSF为电极的电池的峰值输出功率密度分别达到400和230 mW/cm2.这些结果表明,通过 Ni掺杂和原位焙烧,在 LSFN电极颗粒表面制备了均匀分布的 Ni-Fe合金纳米颗粒,极大地提高了铁酸锶镧材料对碳基燃料的催化活性.长期放电测试结果表明, LSF为电极的单电池在测试过程中,尾气可以收集到类似焦油状的黑色物质;而 LSNF为电极的单电池在测试过程中并没有观察到明显的焦油状物质生成.通过气相色谱-质谱联用分析,发现所产生的焦油状物质主要成分是含苯环、碳碳双建或碳碳三键的烃类.这说明 LSF电极只能使 C3H8部分氧化, LSFN对 C3H8等碳氢化合物燃料的氧化具有高的催化活性和良好的耐久性. Ni掺杂的 La0.6Sr0.4FeO3-δ阳极材料是一种有希望的碳基燃料 SOFCs对称电极.     

Carbon nanoribbons and nanotubes based on δ-graphyne: A first-principles study

As a stable allotropy of two-dimensional (2D) carbon materials, δ-graphyne has been predicted to be superior to graphene in many aspects. Using first-principles calculations, we investigated the electronic properties of carbon nanoribbons (CNRs) and nanotubes (CNTs) formed by δ-graphyne. It is found that the electronic band structures of CNRs depend on the edge structure and the ribbon width. The CNRs with zigzag edges (Z-CNRs) have spin-polarized edge states with ferromagnetic (FM) ordering along each edge and anti-ferromagnetic (AFM) ordering between two edges. The CNRs with armchair edges (A-CNRs), however, are semiconductors with the band gap oscillating with the ribbon width. For the CNTs built by rolling up δ-graphyne with different chirality, the electronic properties are closely related to the chirality of the CNTs. Armchair (n, n) CNTs are metallic while zigzag (n, 0) CNTs are semiconducting or metallic. These interesting properties are quite crucial for applications in δ-graphyne-based nanoscale devices.     

H原子在完美δ-Pu金属体相中的扩散行为

采用密度泛函理论的广义梯度近似方法计算了H原子在δ-Pu金属体相中可能稳定存在间隙位置的嵌入能. 计算结果表明, 八面体间隙是H原子最稳定存在位置, 无自旋极化和自旋极化水平的嵌入能分别为-3.12和-2.22 eV. 四面体间隙位的嵌入能相对稍大, 是次稳定存在位置. 通过能量分析推测了单个H原子在完美δ-Pu金属中可能的扩散路径和扩散能垒. 最可能扩散路径为相邻不同间隙位的交替扩散, 八面体间隙到四面体间隙的扩散能垒为1.06 eV, 而四面体间隙到八面体间隙的扩散能垒为0.38 eV. 另外沿平行晶轴方向四面体间隙到四面体间隙交替直线扩散的能垒为1.83 eV, 八面体间隙到八面体间隙交替扩散路径的能垒最高, 为2.52 eV.     

Prins and RCM protocols for the synthesis of the pheromones of the giant white butterfly Idea leuconoe

The total syntheses of (6R)-6-[(2R)-2-hydroxyhexyl]tetrahydro-2H-2-pyranone and 7-hydroxy-5-dodecanolide are described utilizing a Prins reaction and ring closing metathesis reaction sequence.     

Kinetics of Synthesis of Ba1.0Co0.7Fe0.2Nb0.1O3-δ through Solid-Solid Reaction

The mechanism of solid-solid reaction between BaCO₃ and Co₃O₄/Fe₂O₃/Nb₂O₅ has been investigated by means of non-isothermal thermogravimetry and differential scanning calorimetry (DSC) under flowing air gas conditions at atmospheric pressure with a new solid-solid reaction model. The effects of high speed agitating mixing and ball-milling mixing processes on the synthesis kinetics were also studied. The synthesis kinetics of Ba_1.0Co_0.7Fe_0.2Nb_0.1O_3-δ from the BaCO₃ and Co₃O₄/Fe₂O₃/Nb₂O₅ particles was calculated by applying the modified model. The results indicated that the overall reaction process was considered involving two stages: addition reaction between BaCO₃ and Co₃O₄/Fe₂O₃/Nb₂O₅ particles in the first stage and solution reaction between BaCoO₃, BaFeO₃, and BaNbO₃ to form a homogeneous Ba_1.0Co_0.7Fe_0.2Nb_0.1O_3-δ phase in the second stage. The new model matched well with the experimental data. The apparent activation energy of addition reaction stage of the high speed agitating mixing sample was estimated to be 376.76 kJ·mol⁻¹, which was only 3/4 of that of the ball-milling mixing sample (494.76 kJ·mol⁻¹). These results indicated that the high-speed agitating process could enhance atomic diffusion and facilitate the subsequent reaction, thus it is believed as a more effective, energy saving, and environmentally benign mixing process.     

CeO2负载的PdO与Ce1‒x Pd x O2‒δ 物种的甲烷催化燃烧性能

通过调控Pd前驱物在CeO₂上的沉积方式, 分别制备了以PdO和离子态的Ce_1?x Pd _x O_2?δ 物种为主的 Pd/CeO₂催化剂, 并采用X射线光电子能谱(XPS)和拉曼(Raman)光谱确证了这两种Pd物种的存在. 氧气程序升温脱附(O₂-TPD)和氢气程序升温还原(H₂-TPR)的表征结果显示, 相比于与载体相互作用较弱的PdO物种, 与CeO₂相互作用较强的Ce_1?x Pd _x O_2?δ 物种具有更加稳定的Pd—O键. 催化剂的甲烷燃烧反应起燃活性测试结果显示, 以PdO物种为主的催化剂表现出了良好的低温催化性能, 在原料气配比为1%CH₄/4%O₂-Ar, 空速为60000 mL·{\mathrm{g}}_{\mathrm{c}\mathrm{a}\mathrm{t}}^{-\mathrm{1}}·h^?1的条件下, T₁₀和T₉₀分别为275和367 ℃, 而两种以Ce_1?x Pd _x O_2?δ 物种为主的催化剂的T₁₀均超过420 ℃. 催化剂的甲烷程序升温还原(CH₄-TPR)表征结果表明, 在升温过程中只有当PdO或Ce_1?x Pd _x O_2?δ 物种被CH₄还原后, 催化活性才开始上升. 由于PdO物种的Pd—O键强度较弱, 有利于Pd物种上的晶格氧在较低温度下参与CH₄的氧化过程. 而Ce_1?x Pd _x O_2?δ 物种的Pd—O键较稳定, 且在反应条件下离子态Pd²⁺与反应体系中氧物种的作用较强, 进而抑制了其与CH₄的反应, 因此反应的起燃温度较高. 以γ-Al₂O₃为载体采用相同的方法制备了Pd/γ-Al₂O₃催化剂, 相关的表征结果进一步证实, 与载体相互作用较弱的PdO物种更容易被CH₄还原, 进而具有较高的催化活性. 据此可以认为Pd/CeO₂上氧化态的Pd物种被CH₄的还原性能是决定其甲烷催化燃烧反应活性的重要因素之一.     

Separation of fluorinated amino acids and oligopeptides from their non-fluorinated counterparts using high-performance liquid chromatography

Chromatographic conditions for the separation of fluorinated amino acids and oligopeptides from their non-fluorinated counterparts were explored. The separation of six pairs of analytes, including both aromatic and aliphatic fluorocarbons, was investigated at various temperatures using both hydrocarbon and fluorocarbon columns and eluents. Our results show that when hydrocarbon eluents are used, fluorocarbon column provides better separation of fluorinated amino acids or oligopeptides from their non-fluorinated counterparts; when fluorocarbon eluents are used, hydrocarbon column provides better separation of fluorinated amino acids or oligopeptides from their non-fluorinated counterparts. These chromatographic behaviors reflect the fluorophilicity possessed by fluorinated amino acids and oligopeptides.     

Synthesis of gem-difluoromethylenated analogues of anamarine

Practical synthesis of two gem-difluoromethylenated analogues of anamarine was described. The important synthetic steps included the preparation of the key intermediates 20-21 through the indium-mediated gem-difluoropropargylation of aldehyde 18 with the fluorine-containing building block 19 and efficient construction of α,β-unsaturated-δ-lactone scaffold via BAIB/TEMPO procedure.