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1.
Colorectal cancer (CRC) is a leading cause of cancer death worldwide, and about 20% is metastatic at diagnosis and untreatable. Increasing evidence suggests that the heterogeneous nature of CRC is related to colorectal cancer stem cells (CCSCs), a small cells population with stemness behaviors and responsible for tumor progression, recurrence, and therapy resistance. Growing knowledge of stem cells (SCs) biology has rapidly improved uncovering the molecular mechanisms and possible crosstalk/feedback loops between signaling pathways that directly influence intestinal homeostasis and tumorigenesis. The generation of CCSCs is probably connected to genetic changes in members of signaling pathways, which control self-renewal and pluripotency in SCs and then establish function and phenotype of CCSCs. Particularly, various deregulated CCSC-related miRNAs have been reported to modulate stemness features, controlling CCSCs functions such as regulation of cell cycle genes expression, epithelial-mesenchymal transition, metastasization, and drug-resistance mechanisms. Primarily, CCSC-related miRNAs work by regulating mainly signal pathways known to be involved in CCSCs biology. This review intends to summarize the epigenetic findings linked to miRNAome in the maintenance and regulation of CCSCs, including their relationships with different signaling pathways, which should help to identify specific diagnostic, prognostic, and predictive biomarkers for CRC, but also develop innovative CCSCs-targeted therapies.  相似文献   
2.
Liu  Song  Cui  Yuan-Zhen  Zou  Nian-Jun  Zhu  Wen-Hao  Zhang  Dong  Wu  Wei-Guo 《计算机科学技术学报》2019,34(2):456-475
Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front...  相似文献   
3.
为解决电子设备高热通量下的散热问题,采用H2O2氧化法对烧结毛细芯进行了超亲水改性,研究了毛细芯表面润湿性对吸液性能的影响。并将改性后的超亲水毛细芯应用到环路热管内,研究了倾斜角度及加热功率对超亲水毛细芯环路热管的换热特性的影响。实验结果表明:超亲水毛细芯的吸液速度增加,吸液时间较亲水毛细芯减小了3.52ms;与普通亲水毛细芯环路热管相比,在加热功率Q=200W时,超亲水毛细芯环路热管蒸发器中心温度降低了约6.0℃,在Q=20W时启动时间与温度分别降低了33s与2.5℃。同时发现超亲水毛细芯环路热管在正重力状态时的运行温度更低,热阻较小,最低热阻仅为0.084℃/W。  相似文献   
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5.
环路热管作为一种高效的相变传热装置,其性能与位于蒸发器和储液槽之间的毛细芯结构密切相关。为了更深入研究双层毛细芯对环路热管传热性能的影响,利用不同颗粒直径铜粉制备双层毛细芯,在毛细芯总厚度为5 mm的条件下,通过调整大粒径和小粒径层的相对厚度来改变毛细芯厚度比,对平板型蒸发器环路热管启动和变工况运行进行实验测试。实验结果表明:在同一工况下,不同厚度比的双层毛细芯启动特性存在显著差异,启动过程中出现小粒径层蒸发效率低引起的温度过冲和环路热管中气液两相流变化导致的温度振荡;同时存在一个较优的双铜层毛细芯厚度比,大粒径(180~280μm)铜层厚度为3 mm可提高蒸发效率,小粒径(56~71μm)铜层厚度为2 mm可提供足够毛细抽吸力保证环路热管稳定运行。搭载该厚度毛细芯的环路热管不仅启动速度快(125 s),而且总热阻和蒸发器壁面温度均最低,最大加热功率达到120 W(21.10 W/cm~2),对应热阻为0.17 K/W。  相似文献   
6.
章晨  朱秀秀  李闯  邬敏辰 《化工进展》2020,39(7):2788-2794
菜豆环氧化物水解酶1和2(PvEH1、PvEH2)能够动力学拆分外消旋邻甲基苯基缩水甘油醚(rac-oMGE),从而保留(R)-oMGE。基于对PvEH1和PvEH2结构的同源模拟和分析,发现二者分子中的盖子环差异较大,故本文选择盖子环作为研究目标。经融合聚合酶链式反应(FPCR),获得了PvEH2的盖子环区域被PvEH1对应区域替换的杂合酶Pv2Pv1。用全细胞酶E. coli/pv2pv1催化rac-oMGE,当(S)-oMGE刚好水解完全时,产物(S)-3-邻甲苯基-1,2-丙二醇((S)-oTPD)的eepPvEH2的58.3%提高至75.5%。为进一步提高酶的性质,在Pv2Pv1中选取11个氨基酸位点进行丙氨酸(A)突变,获得最优突变子E. coli/pv2pv1K176A,活性为E. coli/pv2pv1(4.2U/g)的2.1倍,且当S构型的底物刚好完全水解时,(S)-oTPD的eep进一步提高为80.3%。分子对接分析发现,盖子环替换和K176位点突变为A,均使(R)-oMGE环氧环中的Cα更易受到酶中D101位点的攻击。利用E. coli/pv2pv1K176A催化150mmol/L rac-oMGE水解制备(R)-oMGE(ees>99%)和(S)-oTPD(eep=80.4%),二者的产率YSYP分别为32.7%和60.1%,时空产率STYS和STYP为1.6g/(L·h)和3.3g/(L·h)。本实验为改善EH的催化性质提供了一种有效策略。  相似文献   
7.
《Ceramics International》2020,46(9):13324-13330
Relaxor ferroelectric 0.75 Pb(Mg1/3Nb2/3)O3-0.25PbTiO3 (0.75PMN-0.25PT) ceramics with Mn-doping concentration of 0%, 1%, 2% and 3 mol% were prepared by two-step sintering. The phase composition, microstructure, dielectric property, ferroelectric property, piezoelectric property and electromechanical property were investigated. Results indicate that all ceramics exhibit pure perovskite phases and high density. Mn-doping induces some decrease in dielectric constant εr, dielectric loss tanδ, remnant polarization Pr, piezoelectric coefficient d33, and electromechanical coupling coefficient kp, while significant increase in mechanical quality factor Qm and the figure of merit (FOM) of 0.75PMN-0.25PT ceramics. For 3 mol% Mn-doped 0.75PMN-0.25PT ceramics, Qm enhances by 1449%, FOM increases by 923%, and tanδ decreases by 67%, which makes it more suitable for high power applications. Interestingly, double P-E loops are observed in 3 mol% Mn-doped 0.75PMN-0.25PT ceramics. The phenomenon was investigated by the symmetry-conforming principle of point defects and the internal bias field.  相似文献   
8.
刘超  谢荣建  董德平 《化工进展》2020,39(8):2980-2988
为了进一步提高回路热管仿真精度并丰富回路热管实验研究方法,本文对回路热管瞬态传质进行实验研究。使用高精度质量流量计分别对以丙酮、乙醇、丙烯为工质的回路热管进行不同负载功率下的质量流量测量研究。结果表明:启动阶段,热负载10W时,丙烯回路比丙酮回路热管启动快,且两者的温度稳定均滞后于质量流量;稳定阶段,随着热负载功率增大,不同工质的回路热管的平均质量流量均线性增长,而瞬态质量流量则持续波动,其质量流量波动幅度均呈现先减小后增大的趋势。质量流量波动幅度会受到气体工质的可压缩性与作用在毛细芯内部上的热量的共同影响。通过频谱分析发现,液相质量流量波动还会受到冷凝器两相区的影响。高热负载下,作用在毛细芯内部上的热量占主导地位,质量流量波动加剧,同时出现周期性大幅波动,且其波动频率随着热负载增大而增大。  相似文献   
9.
The supervision of a hybrid power plant, including solar panels, a gas microturbine and a storage unit operating under varying solar power profiles is considered. The Economic Supervisory Predictive controller assigns the power references to the controlled subsystems of the hybrid cell using a financial criterion. A prediction of the renewable sources power is embedded into the supervisor. Results deteriorate when the solar power is unsteady, owing to the inaccuracy of the predictions for a long-range horizon of 10 s. The receding horizon is switched between an upper and a lower value according to the amplitude of the solar power trend. Theoretical results show the relevance of horizon switching, according to a tradeoff between performance and prediction accuracy. Experimental results, obtained in a Hardware In the Loop (HIL) framework, show the relevance of the variable horizon approach. Power amplifiers allow us to simulate virtual components, such as a gas microturbine, and to blend their powers with that of real devices (storage unit, real solar panels). In this case, fuel savings, reaching 15%, obtained under unsteady operating conditions lead to a better overall performance of the hybrid cell. The overall savings obtained in the experiments amount to 12%.  相似文献   
10.
The topic of value creation through the recovery of returned products in closed loop supply chains is scattered across various bodies of literature. We undertake a systematic literature review of 144 articles in relevant green, reverse and closed loop supply chain literature to synchronize existing knowledge on value creation. Value manifestations of four types of value, namely economic, environmental, information and customer value, are identified. Value adding concepts from the forward- and reverse supply chain may leverage the process of value creation. They are classified into six subclasses, namely partnerships and collaboration, product design characteristics, service concepts, IT solutions, supply chain processes and organizational characteristics. We present a conceptual framework on a strategic level. In this way companies can create competitive advantages by closing the loop. The results of the literature analysis suggest avenues for future research on the operational and strategic level.  相似文献   
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