溶剂抽提法研究煤中小分子相结构

在90℃～100℃温和实验条件下,采用溶剂N 甲基 2吡咯烷酮(NMP)及其与二硫化碳(NMP+CS2)混合溶剂体系对我国7个典型煤种进行抽提研究。研究表明,NMP+CS2(75∶1v v)混合溶剂体系对煤有较好的抽提效果。除无烟煤外,其他6个煤种获得了20%以上的抽提率,长焰煤的抽提率为41%。抽提可溶物利用高效液相色谱进行分离并结合色谱保留指数对物质结构进行分析,实验发现,煤中的活性组分为C6以下的极性组分,而惰性组分为3个芳环的芳烃衍生物。

平朔烟煤大分子结构中的小分子相研究

用硅胶色谱柱将平朔烟煤吡啶抽提物分离成八种不同馏分。通过对这些馏分的数量及其元素分析,平均分子量测定,~1H-NMR 谱图分析,探讨了煤中小分子相的存在形态、氢碳原子分布、芳碳率及芳环被取代程度等,为研究平朔烟煤分子结构提供了精细的结构信息。

角鲛鲨从不受细菌感染

角鲛鲨从不受细菌感染分子生物学家扎斯洛夫在角鲛鲨的胃部，发现叫ｓｑｕａｌａｍｉｎｅ的抗菌素，在杀菌的效力上可与氮卞青霉素媲美。但与氨卞青霉素不同，它同时可杀死原生物和真菌，包括一种折磨免疫抑制病人（如艾滋病患者）的真菌─—念珠菌。扎斯洛夫说，鲨鱼的体...

A stabilized least-squares imaging condition with structure constraints

Conventional shot-gather migration uses a cross-correlation imaging condition proposed by Clarebout （1971）, which cannot preserve imaging amplitudes. The deconvolution imaging condition can improve the imaging amplitude and compensate for illumination. However, the deconvolution imaging condition introduces instability issues. The least-squares imaging condition first computes the sum of the cross-correlation of the forward and backward wavefields over all frequencies and sources, and then divides the result by the total energy of the forward wavefield. Therefore, the least-squares imaging condition is more stable than the classic imaging condition. However, the least-squares imaging condition cannot provide accurate results in areas where the illumination is very poor and unbalanced. To stabilize the least-squares imaging condition and balance the imaging amplitude, we propose a novel imaging condition with structure constraints that is based on the least-squares imaging condition. Our novel imaging condition uses a plane wave construction that constrains the imaging result to be smooth along geological structure boundaries in the inversion frame. The proposed imaging condition improves the stability of the imaging condition and balances the imaging amplitude. The proposed condition is applied to two examples, the horizontal layered model and the Sigsbee 2A model. These tests show that, in comparison to the damped least-squares imaging condition, the stabilized least-squares imaging condition with structure constraints improves illumination stability and balance, makes events more consecutive, adjusts the amplitude of the depth layers where the illumination is poor and unbalanced, suppresses imaging artifacts, and is conducive to amplitude preserving imaging of deep layers.

Small molecular non-fullerene electron acceptors for P3HT-based bulk-heterojunction solar cells

Three small molecules with the same arms and different cores of perylene diimide(PDI)or indaceno[2,1-b:6,5-b']dithiophene(IDT)were designed and synthesized as the acceptor materials for P3HT-based bulk-heterojunction(BHJ)solar cells.The impacts of the different cores on the optical absorption,electrochemical properties,electron mobility,film morphology,photoluminescene characteristics,and solar cell performance were thoroughly studied.The three compounds possess a broad absorption covering the wavelength range of 400–700 nm and relatively low lowest unoccupied molecular orbital(LUMO)energy levels of?3.86,?3.81 and?3.99 eV.The highest power conversion efficiency of 0.82%was achieved for the BHJ solar cells based on SM3 as the acceptor material,the compound with a PDI core.

Paracrine signaling in stem cell renewal and in neoplastic tumor growth

Paracrine pathway activities are being increasingly recognized as instrumental regulatory mechanisms of epithelial-stromal interactions that play important roles in physiological and pathological self-renewal of stem cells and in the initiation and maintenance of neoplastic tumor development.Stromal-specific Hedgehog(Hh)responses and epithelial-associated Wnt pathway activities have been recently appreciated as important factors in stem cell self-renewal and carcinogenesis.Furthermore,Hh and Wnt pathways frequently crosstalk with each other to regulate the growth of epithelial cells in a context-dependent manner.Because small molecule modulators of Hh and Wnt pathway activities are readily available,emerging roles of Hh-Wnt pathway crosstalk in epithelial-stromal interactions will shed light on the development of regenerative and anti-cancer medicines.

Homogeneous label-free fluorescent assay of small molecule-protein interactions using protein binding-inhibited transcription nanomachine

Quantitative analysis of interactions between small molecules and proteins is a central challenge in chemical genetics, molecular diagnostics and drug developments. Here, we developed a RNA transcription nanomachine by assembling T7 RNA polymerase on a small molecule-labeled DNA heteroduplex. The nanomachine, of which the RNA transcription activity can be quantitatively inhibited by protein binding, showed a great potential for small molecule-protein interaction assay. This finding enabled us to develop a novel homogeneous label-free strategy for assays of interactions between small molecules and their protein receptors. Three small molecule compounds and their protein receptors have been used to demonstrate the developed strategy. The results revealed that the protein-small molecule interaction assay strategy shows dynamic responses in the concentration range from 0.5 to 64 nM with a detection limit of 0.2 nM. Due to its label-free, homogeneous, and fluorescence-based detection format, besides its desirable sensitivity this technique could be greatly robust, cost-efficient and readily automated, implying that the developed small molecule-protein interaction assay strategy might create a new methodology for developing intrinsically robust, sensitive and selective platforms for homogeneous protein detection.