High-temperature electrocatalysis and key materials in solid oxide electrolysis cells

Solid oxide electrolysis cells(SOECs)can convert electricity to chemicals with high efficiency at ~600-900℃,and have attracted widespread attention in renewable energy conversion and storage.SOECs operate in the inverse mode of solid oxide fuel cells(SOFCs)and therefore inherit most of the advantages of SOFC materials and energy conversion processes.However,the external bias that drives the electrochemical process will strongly change the chemical environments in both in the cathode and anode,therefore necessitating careful reconsideration of key materials and electrocatalysis processes.More importantly,SOECs provide a unique advantage of electrothermal catalysis,especially in converting stable low-carbon alkanes such as methane to ethylene with high selectivity.Here,we review the state-of-the-art of SOEC research progress in electrothermal catalysis and key materials and provide a future perspective.

数字化学习中的学习者参与:联结学习动机与学习绩效——访俄亥俄州立大学知名学者谢魁教授

在数字化学习领域,如何设计、开发和整合能够提升学生学习动机并促进学生参与的创新技术以提高学习绩效,一直是学术界关注的热点问题。数字化学习环境中的学习者参与作为联结学习动机和学习绩效的桥梁与纽带,由行为参与、认知参与、情感参与、社会性参与四个维度构成。学习者参与能提高学习绩效,但是学习者的社会性参与也可能引起社会性冲突,需要通过社会性冲突演化模型来进行干预和化解。数字化学习动机研究涉及的关键变量包括兴趣、价值感、自治感、胜任感和关系感。研究证实,内部动机和外部动机对学习者参与均具有显著影响。开展数字化学习中学习者参与研究可以引入多种跨学科研究方法,其中经验取样法是一种有效的学习者参与数据采集方法,该方法有助于即时、准确地捕捉参与者的真实体验和感受。未来数字化环境下的学习者参与研究可以从三个方面深化:一是探查数字化学习参与的具体机制,二是设计提高学习者参与度的有效策略,三是寻求研究方法的创新和突破。

Application of ultrasound-guided balloon occlusion in cesarean section in 130 cases of sinister placenta previa

Objective:To investigate the clinical utility of ultrasound-guided balloon occlusion in cesarean section in patients with sinister placenta previa.Methods:The Interventional and Ultrasound Departments of the authors’center assisted obstetrics to complete cesarean section in cases of sinister placenta previa.A total of 130 patients with implanted sinister placenta previa were diagnosed using obstetrical ultrasound and magnetic resonance imaging(MRI).Before cesarean section,the balloon was positioned in the bilateral radial or abdominal aorta.Immediately after delivery of the fetus,the balloon was temporarily filled to transiently seal the target vessel.According to the obstetrician’s assessment of hemostasis,the balloon was withdrawn at the appropriate time.Among the 130 patients,there was one case of abdominal aortic occlusion,with 129 cases blocked by the bilateral common iliac artery.Results:All 130 cases were successfully blocked,with an average blocking time of<15 min,while intraoperative blood loss was 800–1500 ml.Conclusion:Ultrasound-guided balloon blocking treatment before cesarean section can mitigate the dangers of placenta previa and significantly reduce blood loss with no exposure to X-ray radiation.Thus,the technique merits serious consideration.

Modulation of mitochondrial respiration underpins neuronal differentiation enhanced by lutein

Lutein is a dietary carotenoid of particular nutritional interest as it is preferentially taken up by neural tissues. Often linked with beneficial effects on vision, a broader role for lutein in neuronal differentiation has emerged recently, although the underlying mechanisms for these effects are not yet clear. The purpose of this study was to investigate the effect of lutein on neuronal differentiation and explore the associated underpinning mechanisms. We found that lutein treatment enhanced the differentiation of SH-SY5Y cells, specifically increasing neuronal arborization and expression of the neuronal process filament protein microtubule-associated protein 2. This effect was mediated by the intracellular phosphoinositide-3-kinase(PI3K) signaling pathway. While PI3K activity is a known trigger of neuronal differentiation, more recently it has also been shown to modulate the metabolic state of cells. Our analysis of bioenergetics found that lutein treatment increased glucose consumption, rates of glycolysis and enhanced respiratory activity of mitochondrial complexes. Concomitantly, the generation of reactive oxygen species was increased(consistent with previous reports that reactive oxygen species promote neuronal differentiation), as well as the production of the key metabolic intermediate acetyl-CoA, an essential determinant of epigenetic status in the cell. We suggest that lutein-stimulated neuronal differentiation is mediated by PI3K-dependent modulation of mitochondrial respiration and signaling, and that the consequential metabolic shifts initiate epigenetically dependent transcriptomic reprogramming in support of this morphogenesis. These observations support the potential importance of micronutrients supplementation to neurogenesis, both during normal development and in regenerative repair.

搭建高等教育教学数字化转型框架

高等教育正处于数字化转型(Digital Transformation)时代。学习技术和数字平台对教学和学习至关重要。新冠疫情大流行是数字化转型的催化剂,迫使学校、教师和学生迅速转移到在线。一些教师和学生已经为这种转变做好了准备;而那些没有做好准备的教师和学生则不得不迎头赶上。本文提出了一个高等教育机构为加强数字化教学而可能实施的战略响应和结构变革的框架,对当前数字化转型的实践和方向进行了思考。

Porous Single-Crystalline Monolith to Enhance Catalytic Activity and Stability

Engineering the catalytic activity and stability of materials would require the identification of the structural features that can tailor active sites at surfaces.Porous single crystals combine the ordered lattice structures and disordered interconnected pores,and they would therefore provide the advantages of precise structure features to identify and engineer the active sites at surfaces.Herein,we fabricate porous single-crystalline vanadium nitride(VN)at centimeter scale and further dope Fe(Fe0.1V0.9N)and Co(Co0.1V0.9N)in lattice to engineer the active sites at surface.We demonstrate that the active surface is composed of unsaturated coordination of V-N,Fe-N,and Co-N structures which lead to the generation of high-density active sites at the porous single-crystalline monolith surface.The interconnected pores aid the pore-enhanced fluxion to facilitate species diffusion in the porous architectures.In the nonoxidative dehydrogenation of ethane to ethylene,we demonstrate the outstanding performance with ethane conversion of 36%and ethylene selectivity of 99%at 660°C.Remarkably stability as a result of their single-crystalline structure,the monoliths achieve the outstanding performance without degradation being observed even after 200 hours of a continuous operation in a monolithic reactor.This work not only demonstrates the effective structural engineering to simultaneously enhance the stability and overall performance for practically useful catalytic materials but also provide a new route for the element doping of porous single crystals at large scale for the potential application in other fields.

TEMPERATURE SENSITIVITY AND PREDICTION OF THE MECHANICAL BEHAVIORS OF ULTRAFINE GRAINED ALUMINUM UNDER UNIAXIAL COMPRESSION

In the present work, we explore the strain hardening behaviors as well as the effect of temperature on the plastic deformation of ultrafine grained aluminum. The temperature sensitivity is determined and compared with that of coarse grained material. The results indicate that the flow stress of ultrafine grained aluminum displays enhanced sensitivity to temperature. The reduction in activation volume is suggested to be the major reason for the enhanced temperature sensitivity as grain size is refined into the sub-micrometer regime. Finally, a phenomenological constitutive model is proposed to describe the post-yield response of ultrafine grained aluminum.

Identifying and Engineering Active Sites at the Surface of Porous Single-Crystalline Oxide Monoliths to Enhance Catalytic Activity and Stability

Identifying and engineering active sites play a key role in many catalytic reactions.Herein,we create well-defined surface structures through the growth of porous single-crystalline Mn_(3)O_(4) and Mn_(2)O_(3) monoliths at centimeter scale and confine atomically dispersed Pt ions in the lattice at the twisted surface to construct isolated active sites.The activation of lattice oxygen linked to isolated Pt ions is much more effective than the lattice oxygen linked to Mn ions in local structures,leading to an approximately sevento eightfold enhancement of surface oxygen exchange coefficients for catalytic CO oxidation.The active structures of PtO_(1.5) and PtO_(1.4) confined at the well-defined surfaces contribute to the efficient activation of lattice oxygen linked to Pt ions in local structures in addition to the chemisorption of CO in the oxidation reaction.We demonstrate the complete CO oxidation with air at 65℃ without degradation being observed even after continuous operation of 300 h.