Identification of the activity source of CO2 electroreduction by strategic catalytic site distribution in stable supramolecular structure system

Identification of the real catalytic site in CO₂ reduction reaction (CO₂RR) is critical for the rational design of catalysts and the understanding of reactive mechanisms. In this study, the catalytic activity of pyridine-containing materials was for the first time structurally demonstrated in CO₂RR by crystalline supramolecular coordination compounds model system. The system consists of three stable supramolecular coordination compounds (Ni-TPYP, Ni-TPYP-1 and Ni-TPP) with different numbers (4, 2 and 0) of active pyridine groups (i.e. uncoordinated pyridine nitrogen atoms). The electrocatalytic test results show that with the decrease of the number of active pyridine groups, the CO₂RR performance is gradually reduced, mainly showing the reduction of highest FE_CO (99.8%, 83.7% and 25.6%, respectively). The crystallographic, experimental and theoretical evidences prove that the CO₂RR activity is more likely derived from uncoordinated pyridine nitrogen than the electrocatalytic inert metal nickel in porphyrin center. This work serves as an important case study for the identification of electrocatalytic activity of pyridine-containing materials in CO₂RR by simple supramolecular model system.     

对高校本科教学工作水平评估方案与高校图书馆新规程的评析

作为共同指导和规范高校图书馆工作及其关系的《普通高等学校本科教学水平评估方案（试行）》,其中对图书馆评估的指标体系与《普通高等学校图书馆规程（修订）》之间应是竟合,而不应不和谐。文章针对《方案》与《规程》不和谐的事实,分析了产生不和谐的原因及法律后果,提出了解决办法。     

新西兰高中学业评价制度改革成效与反思

国家教育成就证书（NCEA）是新西兰于2002年引入的一种全新高中学业评价制度,以满足社会对人才培养类型多样化的需求。2018年,新西兰教育部对NCEA发起了一场大规模的回顾与审查,旨在了解十余年间NCEA的实施效果。审查结果显示,NCEA以其灵活的学习方式、多样化的评价标准以及全面的学业成绩报告单等优势获得了公众的高度认可,然而也有不同声音认为课程学习过分关注评价、师生课业负担过重以及内部评价标准差异过大。针对这些反馈结果,新西兰教育部采取了如下调整策略：强化课程知识的系统学习,简化NCEA的学分结构,重新订正评价标准,以便NCEA为个体与社会提供更好服务。     

基于信息增强的多视角矩阵分类器设计

由于受限于人工成本,很多现实世界中的多视角数据集是由少量有标签样本和大量无标检样本组成的。当前传统的多视角矩阵分类器无法有效处理这类数据集。为了处理这个问题,将Universum学习引入多视角矩阵分类器中,提出基于信息增强的多视角矩阵分类器。由于Universum学习可以生成额外的无标签样本,这类样本虽然没有被指定类别标签,但是包含了部分有标签样本的信息,所以Universum学习可以增强有效样本信息。实验表明,相比于传统的多视角矩阵分类器,本文提出的基于信息增强的多视角矩阵分类器具有更好的分类性能。     

Direct observation of nodeless superconductivity and phonon modes in electron-doped copper oxide Sr1−xNdxCuO2

The microscopic understanding of high-temperature superconductivity in cuprates has been hindered by the apparent complexity of crystal structures in these materials. We used scanning tunneling microscopy and spectroscopy to study the electron-doped copper oxide compound Sr_1−xNd_xCuO₂, which has only bare cations separating the CuO₂ planes and thus the simplest infinite-layer structure of all cuprate superconductors. Tunneling conductance spectra of the major CuO₂ planes in the superconducting state revealed direct evidence for a nodeless pairing gap, regardless of variation of its magnitude with the local doping of trivalent neodymium. Furthermore, three distinct bosonic modes are observed as multiple peak-dip-hump features outside the superconducting gaps and their respective energies depend little on the spatially varying gaps. As well as the bosonic modes, with energies identical to those of the external, bending and stretching phonons of copper oxides, our findings reveal the origin of the bosonic modes in lattice vibrations rather than spin excitations.     

Detection of preanalytical errors in arterial blood gas analysis

IntroductionBlood gas analysis (BGA) is an essential test used for years to provide vital information in critically ill patients. However, the instability of the blood gases is a problem. We aimed to evaluate time and temperature effects on blood gas stability.Materials and methodsArterial blood was collected from 20 patients into syringes. Following BGA for baseline, syringes were divided into groups to stand at 4°C and 22°C for 30, 60, 90, 120 minutes. All were tested for pH, partial pressure of carbon dioxide (pCO₂), partial pressure of oxygen (pO₂), oxygen saturation (sO₂), oxyhemoglobin (O₂Hb), sodium, potassium, glucose, lactate, oxygen tension at 50% hemoglobin saturation (p50), and bicarbonate. A subgroup analysis was performed to detect the effect of air on results during storage. Percentage deviations were calculated and compared against the preset quality specifications for allowable total error.ResultsAt 4°C, pO₂ was the least stable parameter. At 22°C, pO₂ remained stable for 120 min, pH and glucose for 90 min, lactate and pCO₂ for 60 min. Glucose and lactate were stable when chilled. Air bubbles interfered pO₂ regardless of temperatures, whereas pCO₂ increased significantly at 22°C after 30 min, and pH decreased after 90 min. Bicarbonate, sO₂, O₂Hb, sodium, and potassium were the unaffected parameters.ConclusionsCorrect BGA results are essential, and arterial sample is precious. Therefore, if immediate analysis cannot be performed, up to one hour, syringes stored at room temperature will give reliable results when care is taken to minimize air within the blood gas specimen.     

OSPFv3和OSPFv2的差异分析

IPv6是为适应Internet的发展而在IPv4的基础上产生的新一代IP协议。当前支持IPv6的较为成熟的路由协议有RIPng和OSPFv3,其中,OSPFv3是当前应用最广泛的域内路由协议。文章通过对OSPFv3和OSPFv2的对比,分析了OSPFv2与OSPFv3之间的主要差异。     

基于p2p文件共享的数字版权管理模型

近年来随着p2p(peer-to-peer)文件共享软件的广泛使用,知识产权的保护问题日益突出,由于p2p文件共享软件允许对等点之间直接的文件交换,并且较少的依赖服务器的管理,版权保护越发困难。本文首先分析了p2p网络下知识产权保护面临的困难,以及目前数字版权管理系统DRM(DigitalRightsManagement)系统面临的挑战,提出了两种适用于p2p文件共享的数字版权管理方案,并分析和讨论了目前存在的问题,最后指出了进一步的研究方向。     

急性运动对人体细胞免疫功能的影响

为探索运动对细胞免疫功能的影响，检测了7名男运动员一次急性疲劳性运动前和运动后即刻、3h、24h的外周血TLT、IH活性和皮质醇及胰岛素浓度的变化。结果：在运动后即刻，TLT显著增强，IL—2活性和血浆皮质醇浓度分别略有上升和下降；在运动后3h，前2项指标和血浆皮质醇浓度分别明显增强和降低。这3项指标在运动后24h均恢复到运动前水平。IL-2活性变化与皮质醇变化有显著负相关关系。胰岛素在运动前后无明显变化。结果表明：一次急性适度运动可提高人体的细胞免疫功能，并可持续数小时。这种变化与血浆皮质醇浓度下降有一定关系。     

实时数据库系统并发控制机制分析

实时数据库系统中的事务具有显示的时间约束,因此,与传统的数据库系统相比,实时数据库系统并发控制协议有了一定的扩展。在分析实时数据库系统中实时事务并发执行的新特点的基础上,介绍了几种典型的实时数据库并发控制协议。