Lead-free sodium niobate nanowires with strong piezo-catalysis for dye wastewater degradation

In this work, the hydrothermally-synthesized sodium niobate nanowires were used to decompose Rhodamine B dye solution through the piezo-catalytic effect. With the sodium niobate catalyst, a high piezo-catalytic degradation ratio of ～80% was achieved under the excitation of vibration for the Rhodamine B dye solution (～5?mg/l). These active species in the catalytic process, hydroxyl radicals and superoxide radicals with the strong oxidation ability, were also observed, which confirmed the key role of piezoelectric effect for piezo-catalysis. The piezo-catalysis of sodium niobate nanowires provides a high-efficiency and reusable tool in application in depredating the dye wastewater.     

植物细胞分裂素ortho-Topolin Riboside对人白血病细胞株THP-1的抗癌活性及机制初探

本研究以人急性髓性白血病细胞株THP-1为研究对象,初步探讨其抗癌活性及作用机制。通过光学显微镜观察N6-2-苄胺羟基腺苷(oTR)作用后THP-1细胞形态学和数目变化;CCK-8法检测oTR对THP-1细胞的增殖抑制作用,并用核苷转运体拮抗剂和腺苷受体拮抗剂预处理细胞检测oTR进入细胞的方式;用流式细胞仪分析oTR作用对THP-1细胞凋亡和分化的影响。结果表明,oTR可显著(P<0.05)抑制THP-1细胞的增殖能力,且呈浓度依赖性;核苷转运体拮抗剂Dipyridamole预处理THP-1细胞后,可明显逆转oTR的增殖抑制作用,而4种腺苷受体拮抗剂(DPCPX、SCH58261、MRS1754和MRA1191)则无显著影响;oTR可诱导处理组细胞亚倍体峰比例显著(P<0.05)高于对照组,且细胞髓系分化标志蛋白CD11b表达明显升高。以上结果表明细胞分裂素oTR通过核苷转运体途径进入THP-1细胞,显著(P<0.05)抑制细胞的增殖,并可诱导THP-1细胞发生凋亡和髓系分化。     

致密油藏注天然气提高采收率研究现状

随着我国石油需求量不断增加,致密油藏的开发也愈发重要。如何高效开发致密油藏是一项重点难点,其中致密油藏注天然气提高采收率是一个极具潜力的研究方向。因此,本文着重介绍以天然气作为能量补充介质在国内外的研究现状和应用现状,并且从两相特征等方面总结了理论研究中的一些机理,对致密油藏注天然气提高采收率的发展前景进行了一定的展望。     

Effect of Temperature and Strain Rate on the Hot Deformation Behaviour of Ferritic Stainless Steel

Metals and Materials International - The flow behaviour and microstructure characteristics of a ferritic stainless steel were investigated using plain strain compression test on a Gleeble 3500...     

Filtered adaptive constrained sampled-data control for uncertain multivariable nonlinear systems

A filtered adaptive constrained sampled-data controller for uncertain multivariable nonlinear systems in the presence of various constraints is synthesized in this paper. A piecewise constant adaptive law drives that estimation error dynamics to zero at each sampling time instant yields adaptive parameters. The filtered control scheme consists of two components. Based on an estimation/cancellation strategy, a disturbance rejection control law is designed to compensate the nonlinear uncertainties within the bandwidth of low-pass filters, whereas a constraint violation avoidance control law is designed to solve an online constrained optimization problem. Although a reduced sampling time helps to minimize the estimation error caused by the neglect of unknowns, the resulting aggressive signals put more restrictions on the control law. Greater sacrifice of tracking performance is required to satisfy the constraints. The constraints violation avoidance control law is in favor of a larger sampling time. Sufficient conditions are given to guarantee the stability of the closed-loop system with the sampled-data controller, where the input/output signals are held constant over the sampling period. Numerical examples are provided to validate the theoretical results, comparisons between the constrained sampled-data controller and unconstrained adaptive controller with the implementation of different sampling times are carried out.     

樟芝多糖通过降低NLRP3 Caspase1炎性小体表达改善帕金森小鼠神经行为学的机制研究

目的:研究樟芝多糖通过降低NLRP3-Caspase1炎性小体表达改善6-OHDA构建的帕金森小鼠模型的行为学机制。方法:利用6-OHDA脑内注射构建帕金森小鼠模型，通过酪氨酸羟化酶（TH）免疫组化染色和行为学判定小鼠模型的构建成功。利用樟芝多糖进行干预，分别在干预前、干预后的第1、3、7天4个时间点进行神经行为学实验，分别采用转棒实验、爬杆实验检测小鼠自主行为能力以及协调能力，4个时间点取小鼠尾静脉外周血采用ELISA法检测外周血中Caspase1和IL-1β的表达，樟芝多糖干预第7天时待进行完行为学实验后小鼠断颈处死，取小鼠脑组织-纹状体，Western blot法检测纹状体中Caspase1、proCaspase1、NLRP3的表达，高效液相色谱检测纹状体中单胺类神经递质的表达，RT-QPCR检测Caspase1、NLRP3、IL-1β、IL-4、IL-6的mRNA表达。NISSl染色检测小鼠脑组织神经细胞凋亡情况。 结果:6-OHDA脑内注射可以造成小鼠帕金森样病变，且TH蛋白表达显著下调，樟芝多糖干预后小鼠的行为学得到显著改善（P<0.05），纹状体中Caspase1、proCaspase1、NLRP3的表达显著下调，与模型小鼠相比具有统计学差异（P<0.05），且相关炎症因子Caspase1、NLRP3、IL-1β、IL-4、IL-6的mRNA表达下调（P<0.05），纹状体中单胺类神经递质表达上升（P<0.05）。结论:樟芝多糖可以通过下调NLRP3-Caspase1炎性小体表达来改善6-OHDA构建的帕金森小鼠模型行为改善，这可能是樟芝多糖治疗帕金森的机制之一。     

Effect of an abrupt change in pulling rate on microstructures of directionally solidified Al2O3-Er3Al5O12 eutectic and off-eutectic composite ceramics

Directionally solidified microstructures of Al₂O₃-Er₃Al₅O₁₂ eutectic and off-eutectic in situ composite ceramics were explored under abrupt-change pulling rate conditions. Corresponding temperature distributions and interface locations were studied. In eutectic composition, fluctuation of eutectic spacing occurred when the pulling rate increased abruptly. A gradually increase or abrupt increase in eutectic spacing was observed when the pulling rate decreased abruptly. In hypoeutectic and hypereutectic compositions, formation of the primary phases were suppressed when the pulling rate increased abruptly from 10?µm/s to 100?µm/s, while primary phases precipitated when the pulling rate decreased abruptly from 100?µm/s to 10?µm/s. The interface altitude decreased after the pulling rate increased abruptly, but increased after the pulling rate decreased abruptly. The liquid composition restriction (around the eutectic composition) at the eutectic interface plays an important role in the suppression of the primary dendrite and coupled eutectic oxides can be obtained in off-eutectic compositions even under higher solidification rate conditions.