Guazia,the earliest ovule without cupule but with unique integumentary lobes

The earliest ovules in the Late Devonian (Famennian) are surrounded by a cupule that is involved in both protection and pollination, and generally have free integumentary lobes. Here we report a new taxon from the Famennian of China, Guazia dongzhiensis gen. et sp. nov. The terminally borne ovule is apparently acupulate (without cupule) and has four radially arranged wing-like integumentary lobes that are extensively fused, and folded lengthwise and inwards. Guazia provides evidence that not all Devonian seeds possess a cupule and it increases their diversity in integumentary lobes. This genus also suggests that the integuments develop new functions, probably including wind dispersal at the expense of the cupules.     

基于油气藏渗流力学课程的创新创业深度研究融合

"油气藏渗流力学"作为石油工程专业主干课程,在日常教学中,多为理论知识教学,缺少实践教学活动。本文通过问卷调查,得出创新创业教育实际情况的相关数据。根据实际情况,以创新创业为方向,将其思想与内涵同"油气藏渗流力学"的教学计划及活动相结合。从课上到课下,从学校到学生,全方位、深层次、多方向地提出了模块教学、合理规划科技创新竞赛及跨专业联合教学模式三种教学改革方式。     

开关电源实验教学探讨

开关电源采用交—直—交—直变换技术,是一种组合变流电路,包含整流、逆变、变压、滤波等电路,融汇了电力电子技术及其课程教学的主要内容,对学生提炼电力电子技术课程教学的关键知识点有很大的作用。通过该实验,帮助学生深入学习与理解电力电子技术的基本知识,培养和提高实验技能以及分析问题和解决问题的能力,取得了良好的实验教学效果。     

漳平水仙饼茶中酚类提取物的体外抗氧化活性及对小鼠乳腺癌4T1细胞增殖和转移的抑制作用（英文）

目的:探讨不同提取方法所得的漳平水仙饼茶中提取物的主要化学成分、体外抗氧化作用和对小鼠乳腺癌4T1细胞增殖和转移的抑制作用。创新点:首次对漳平水仙饼茶中不同提取物的主要化学成分、体外抗氧化作用和对小鼠乳腺癌4T1细胞增殖和转移的抑制作用进行了研究。方法:以漳平水仙饼茶为原料,利用乙酸乙酯、正丁醇和水分别进行萃取,得到三种提取物。对提取物的茶多酚、黄酮、原花青素、总糖、蛋白质、氨基酸、儿茶素单体、茶黄素、咖啡碱等主要化学成分进行检测。利用DPPH、ABTS和FRAP三种不同方法进一步检测了三种提取物的体外抗氧化性,并评价了提取物对小鼠乳腺癌4T1细胞的增殖、细胞周期、迁移、侵袭等的影响作用。同时,采用皮尔森系数分析和聚类分析两种分析方法探讨了提取物中的化学成分与其抗氧化活性和对4T1细胞作用的相关性。结论:本实验结果显示,漳平水仙饼茶乙酸乙酯层提取物具有最高的茶多酚、黄酮、原花青素和儿茶素单体的含量(表1~3,图1),并且在三种不同的抗氧化体系中均显示出最强的抗氧化性能(表4,图2),同时对小鼠乳腺癌4T1细胞的增殖、细胞周期、迁移、侵袭有非常明显的抑制作用(图3~6)。乙酸乙酯层提取物之所以具有最强的生物活性主要与其含有较多的茶多酚等活性成分有关(表5,图3)。     

Sources of difficulty in assessment: example of PISA science items

ABSTRACT

The understanding of what makes a question difficult is a crucial concern in assessment. To study the difficulty of test questions, we focus on the case of PISA, which assesses to what degree 15-year-old students have acquired knowledge and skills essential for full participation in society. Our research question is to identify PISA science item characteristics that could influence the item’s proficiency level. It is based on an a-priori item analysis and a statistical analysis. Results show that only the cognitive complexity and the format out of the different characteristics of PISA science items determined in our a-priori analysis have an explanatory power on an item’s proficiency levels. The proficiency level cannot be explained by the dependence/independence of the information provided in the unit and/or item introduction and the competence. We conclude that in PISA, it appears possible to anticipate a high proficiency level, that is, students’ low scores for items displaying a high cognitive complexity. In the case of a middle or low cognitive complexity level item, the cognitive complexity level is not sufficient to predict item difficulty. Other characteristics play a crucial role in item difficulty. We discuss anticipating the difficulties in assessment in a broader perspective.     

抚州市产业结构与就业结构协调发展研究——基于结构偏离度的分析

本文基于产业结构偏离度指标分析得出:抚州市产业结构和就业结构发展不协调,就业结构滞后于产业结构,第一产业剩余劳动力有待转出;第二产业吸纳劳动力的潜力较大;第三产业存在着过剩的劳动力,劳动生产率较低,产业内劳动力有面临着向其他产业转移的压力。进而提出优化工业内部结构,拓宽就业主渠道;优先发展第三产业中前向、后向关联效应大,对就业带动效应较大的行业;调整农业内部结构,扩大第一产业内部就业等政策建议。     

Sub-nanomolar detection of thrombin activity on a microfluidic chip

Bioluminescence resonance energy transfer (BRET) is a form of Förster resonance energy transfer. BRET has been shown to support lower limits of detection than fluorescence resonance energy transfer (FRET) but, unlike FRET, has not been widely implemented on microfluidic devices for bioanalytical sensing. We recently reported a microscope-based microfluidic system for BRET-based biosensing, using a hybrid, high quantum-efficiency, form of BRET chemistry. This paper reports the first optical fiber-based system for BRET detection on a microfluidic chip, capable of quantifying photon emissions from the low quantum-efficiency BRET² system. We investigated the effects of varying core diameter and numerical aperture of optical fibers, as well as varying microfluidic channel design and measurement conditions. We optimized the set-up in order to maximize photon counts and minimize the response time. The optimized conditions supported measurement of thrombin activity, with a limit of detection of 20 pM, which is lower than the microscope-based system and more than 20 times lower than concentrations reported to occur in plasma clots.     

船舶运动数据在字符与数值混合通信中的简易压缩方法

通过对船舶运动数据的分析,提出了在具体应用条件下一种船舶运动数据的简易压缩方法。     

In situ growth of large-area and self-aligned graphene nanoribbon arrays on liquid metal

Intrinsic graphene features semi-metallic characteristics that limit its applications in electronic devices, whereas graphene nanoribbons (GNRs) are promising semiconductors because of their bandgap-opening feature. However, the controllable mass-fabrication of high-quality GNR arrays remains a major challenge. In particular, the in situ growth of GNR arrays through template-free chemical vapor deposition (CVD) has not been realized. Herein, we report a template-free CVD strategy to grow large-area, high-quality and self-aligned GNR arrays on liquid copper surface. The width of as-grown GNR could be optimized to sub-10 nm with aspect ratio up to 387, which is higher than those of reported CVD-GNRs. The study of the growth mechanism indicates that a unique comb-like etching-regulated growth process caused by a trace hydrogen flow guides the formation of the mass-produced self-aligned GNR arrays. Our approach is operationally simple and efficient, offering an assurance for the use of GNR arrays in integrated circuits.     

CERN document server: Document management system for grey literature in a networked environment

Conclusion In this paper we briefly described the current status of research in the field of digital libraries interoperability, mainly with respect to federated data processing such as permitted within the Open Archive Initiative framework. We then presented the CERN Document Server Software suite that is a free software package main-tained by CERN providing an online digital library solution for mid- to large-sized document repositories. The set of CDSware modules was described and the differ-ences with other existing tools briefly mentioned. Finally we have mentioned a typical usage statistics illustrating the scope of grey literature and networked con-ditions of the CERN Document Server. We pointed out that the current trend in grey literature management goes toward institutional repositories build upon the distributed and federated model. Further research is going on within the CDS collaboration in this area, focused particularly on (i) semantic interoperability using ontologies in distributed and federated data processing and (ii) ranking technologies when searching grey literature in OAI compliant repositories.