疯狂干细胞

人体的每一个细胞都有创建整个身体的完整的遗传密码,但当我们的细胞成熟后,它们就专门化了,很多基因都不再活动。但干细胞例外,干细胞是所有细胞之母,作为机体的原始细胞,它能够自我复制、多向分化,在整个生命过程中保持重新生长成任何类型细胞的能力。在特定条件下,它甚至还能分化成多种功能细胞或者组织器官。     

高糖对大鼠骨髓间充质干细胞增殖及凋亡的影响

目的 分离培养和鉴定大鼠骨髓间充质干细胞(BMSCs),探讨高浓度葡萄糖对BMSCs增殖及凋亡的影响.方法 贴壁培养法分离纯化Wister大鼠BMSC,体外培养和连续传代.将传至第三代的BMSCs用低糖-DMEM培养液(含葡萄糖5.6 mmol/L)制成细胞悬液,计数并接种于培养瓶中,待细胞贴壁后,分组加入含不同浓度葡萄糖(5.6mmol/L、11 mmol/L、25 mmol/L、40 mmol/L)的DMEM培养液,短期组培养3～4天,长期组培养4周.分别收集细胞,噻唑蓝(MTT)法检测细胞增殖,Annexin-V/PI法检测其凋亡.结果 在实验研究中,与高糖对内皮祖细胞(endothelial p rogenitor cells,EPCs)等的影响不同,一定浓度的高糖并不显著抑制BMSCs的增殖,并不促进BMSCs的凋亡率显著增加.25 mmol/L的高糖有助于BMSCs成骨分化.结论 短期和长期(4周)培养,BMSCs具有显著的高糖耐受性.与低糖条件相比,高糖提高了细胞的成骨分化能力.     

创新地图

纽约干细胞研究基金会的科学家运用克隆技术制造出干细胞。他们将成年人的细胞DNA与卵细胞中的遗传物质融合，帮助细胞分裂并产生干细胞。不过，这种细胞并不是常规意义上的干细胞，其内部还含有来自卵细胞的染色体。接下来，科学家们将要尝试抑制多余染色体或将其从干细胞中剔除。这项技术位居今年《时代》周刊十大医学突破榜首。     

3D打印初见成效：美国成功打印“天然心脏”

美国路易斯维尔大学威廉斯领导的研究团队已经利用人体脂肪干细胞，成功3D打印出心脏血管和心脏瓣膜，待一颗心脏的所有部件打印完毕后，再将其组装起来。     

癌细胞和干细胞或有相同起源

据美国物理学家组织网7月19日（北京时间）报道，人们一般认为，致癌基因是一些在变异时将健康基因变成癌症肿瘤细胞的基因，然而美国科学家的最新研究却表明，致癌基因也能将健康的细胞变成类似于干细胞的细胞，科学家可以据此研发出更安全实用的干细胞疗法来治疗多发性硬化症和癌症等疾病。     

扁蓿豆的组培

一、材料及处理扁蓿豆(Pocockia ruthenica)种子经1%升汞处理10分钟,无菌水洗五次后,接种子发芽培养基上,七天后即生成2～3叶龄的无菌苗,取其茎、叶为外植体。二、培养方法1.诱导愈伤组织与分化:将无菌苗之茎、叶在超静工作台上切成0.5cm长的片段,接入成愈培养基,进行暗培养,一般七     

药用植物干细胞培养技术的应用分析

植物的作用来源较多,其中既是许多药用化学物质的重要来源,也是对一些新药的理想探索根源。而今,药用植物方面的大量研究事实证明,该研究具有一定的研究价值、意义,也因此使得这方面的研究不断提升,引起了极度关注。本文在了解植物干细胞的基础上,介绍了药用植物干细胞的培养技术及其应用,希望此次的探究对以后的研究学者有一定的借鉴。     

风险投资的分阶段投资策略

概述了创业企业成长阶段的几类较流行的划分方法 ,从经营活动内容、新技术生命周期和投融资来源相结合的角度,将创业企业的发展过程分为种子期、开发期、成长期和成熟期四个阶段,并针对创业企业在四个发展阶段所面临的不同风险,分析了风险投资者在构造投资舍约时应着重注意的一系列问题以及应采取的相关策略.     

产业集群竞争优势理论分析

产业集群是现代经济中一类重要的产业间新的组织形式,其强劲的竞争优势成为了国家或地区竞争力的重要来源.学术界对产业集群竞争优势展开了多视角的研究,本文综述和归纳了众多的产业集群竞争优势理论,认为各种理论对产业集群的竞争优势主要是从集群产业集聚、集群组织与生产方式、集群创新三个方面进行分析的.     

移植物抗宿主病（GVHD）早期诊断试剂

移植物抗宿主病 移植物抗宿主病是一种来自供体的细胞与患者细胞发生反应、成胁生命的异体（非自体）干细胞移植（例如骨髓，外周血或脐带血移植）并发症。据文献报道．移植物抗宿主病的发生率存所有异体干细胞移植患者中高达50％。     

Expected Development Time Reductions in the German Mechanical Engineering Industry

This article presents initial results of field studies on the product development practices in German mechanical engineering companies. The investigation concentrates on managers' estimates on how much and by what means they could reduce cycle time and resource usage if the projects had been managed differently. In his analysis of fourteen development projects, Philipp Murmann reports that managers expect a reduction of development time as well as of development resources by 30% if appropriate activities would be employed. Parallel tasking and efficiency improvements account for the potential savings. Paralleling effects are project related, while improvements external to the projects cause efficiency-effects. Ten identified internal and external activities were expected to be of major importance in the reduction of development times. Major improvements are found among activities concentrated at the front end of development process.
Further analyses show that primary and secondary activities can be separated; however, all of these activities need to be activated in order to achieve the anticipated results.     

Enhanced and conventional project-based learning in an engineering design module

Engineering education focuses chiefly on students’ ability to solve problems. While most engineering students are proficient in solving paper questions, they may not be proficient at providing optimal solutions to pragmatic project-based problems that require systematic learning strategy, innovation, problem-solving, and execution. The present study aims to determine whether an enhanced Project-based learning (PBL) with appropriate innovative interventions leads to increased students’ ability to achieve better learning and project outcomes. The interventions refer to incorporating added learning and facilitating methods, namely, (1) use of mind-maps; (2) employment of analogies; and (3) use of round-table discussions. The study was conducted with a total number of 60 first-time PBL students equally divided into two classes with one serving as an experimental class and another as a control class. In addition, one class of students had a lower academic standing compared to the other (control). The rubric for the project-based module included a written knowledge test and a scenario-based oral examination to test knowledge and problem-solving skills, a artefact demonstration to evaluate artefact’s performance. A major finding of this study was that there were significant differences in knowledge scores, problem-solving ability and artefact performance between students undergoing conventional and enhanced PBL methods. It could also be inferred from this study that students who had undergone enhanced PBL method designed better systems and had better performing artefacts than those who were subjected to the conventional PBL approach. Finally, it was concluded that incorporating enhanced learning and facilitating methods to group-centric, project-based driven education provided a more fertile environment to promote better learning experience and improved problem-solving ability which could eventually lead to developing innovative and pragmatic solutions to real-world engineering problems.     

Evaluating students with online testing modules in engineering economics: A comparision of student performance with online testing and with traditional assessments

Abstract

Engineering economics courses often require students to take time-constrained, in-class exams in which they solve problems by hand, possibly referring to interest rate tables. Many students rely on partial credit to successfully pass exams. Outside of the classroom, professionals rely on computers to solve engineering economics problems, which raises the question of whether engineering economics courses are correctly assessing student performance. This article describes the study of a large engineering economics class using a non-conventional testing method. Student performance was evaluated using online testing modules with a stringent passing criterion, and the tests could be taken multiple times. The questions for each testing attempt were pulled from a database so that students received a new question every time. We compare the performance of students who were assessed using traditional methods with the performance of students assessed with these online testing modules. Our analysis shows that, overall, students who were assessed using the online testing modules earned better grades than students who were assessed via traditional methods. The analysis also discusses several benefits and drawbacks to using online assessments compared with traditional methods. The online assessment method could be useful in large engineering courses that are formula-based.     

Nominal and Real Required Returns in Present Value Analysis

Present value analysis is complicated by uncertainty about future inflation. If it so happened that real cash flows did not depend on inflation and real required returns were close to zero, then inflation and required returns could be omitted from present value analysis. Unfortunately, they cannot. This paper shows that real cash flows are typically sensitive to inflation and that, outside of the 1950s and 1960s, real interest rates, have not been very stable or close to zero. There have consequently been many years when a neglect of inflation and interest rates would have caused substantial present-value errors. It is also argued that interest rates on Treasury and Corporate AAA bonds are only appropriate for virtually risk-free projects. An engineering project normally commands a substantial risk premium and the neglect of such premia can cause a large overestimate of a project's present value.     

微生物传感器研究进展

对微生物传感器结构、功能及其在环境监测、生物工程、医学等领域的最新应用进行了综合评述,探讨了微生物固定化方法对传感器性能的影响,并对微生物传感器研究进展和应用前景进行了分析展望。     

Assessing creative thinking in design-based learning

Infusing creative thinking competence through the design process of authentic projects requires not only changing the teaching methods and learning environment, but also adopting new assessment methods, such as portfolio assessment. The participants in this study were 128 high school pupils who have studied MECHATRONICS from 10th to 12th grades (16–18 years old). By the end of 12th grade, the pupils had created 57 authentic projects. The intervention program had two parts: first, the pupils documented their project according to a creative design process that had been introduced to them. Second, the projects were assessed according to a creative thinking scale. This scale was designed to assist pupils in documenting the design process. It could be used as a guideline for teachers and pupils during the course of the project. The research examined pupils’ performance during project-based learning. The research tools included: observations of class activities, portfolio assessment, and external matriculation assessment. The findings show first that pupils learned to document their design process. Second, pupils’ projects demonstrated various levels of creative thinking skill. Evidences for high-level documentation of the projects were found in pupils’ portfolios. On the other hand, there is much to be learned about documenting teamwork and pupils’ reflection. This research could assist researchers and teachers who are interested in assessing engineering education outcomes.     

Engineering and technology students’ perceptions of courses

As cultural, social, political and economic changes take place, the secondary or high school curriculum should reflect and respond to changing needs and aspirations of students. Technology Education has been proactive in this arena as it has transformed over the decades to meet ever-changing societal needs. The most recent change to the discipline has been to add engineering and, as a result, adopting a new name and curriculum-Engineering and Technology Education. The added component and name change in Technology Education is causing discussions about what the new direction means, what professional preparation changes will be incurred, and what work graduating students will be prepared to do. In light of these changes, this study investigated perceptions of high school students in the United States of America about engineering and technology courses they take. To investigate whether students’ perceptions are in accord with current changes in Engineering and Technology Education, 316 students enrolled in engineering and technology courses in Georgia schools that have an affiliation with the Georgia Engineering and Technology Education Association (GETEA) were surveyed. According to data analyses, students’ perceptions can be divided into two factors. Educational Value of Course (factor 1) was extracted from statements measuring the degree to which the courses prepare students for employment and provide them with information regarding future employment. Personal Relevance of Course (factor 2) was derived from statements measuring students’ perceptions about links between engineering and technology education and their personal lives. Such findings suggest these students valued their engineering and technology courses, planned to continue their education, made good grades, and had varied types of career expectations for jobs such as design engineers and architects.     

Middle-school teachers’ understanding and teaching of the engineering design process: a look at subject matter and pedagogical content knowledge

This paper reports on research investigating six middle school teachers without engineering degrees as they taught an engineering unit on the engineering design process. Videotaped classroom sessions and teacher interviews were analyzed to understand the subject matter and pedagogical content knowledge the teachers used and developed as they introduced the eight steps of the engineering design process (from content standards for the state of Massachusetts, USA). The teachers demonstrated wide-ranging knowledge of the engineering design process, and this paper describes two of the steps the teachers showed a more sophisticated understanding—constructing a prototype and redesigning. Examples from the teachers illustrate strengths that can be built upon as well as some areas for further development.     

Assessing the effectiveness of a technical assistance program: The case of maize seed relief to vulnerable households in Zimbabwe

The recent economic downturn in Zimbabwe impoverished the majority of households. To assist vulnerable rural households improve their food security, the British Department for International Development implemented a seed relief program from 2003/2004 to 2005/2006 that emphasized recycling of maize open pollinated varieties (OPV). Using data collected from 597 households in six districts in 2006, this study assesses the effectiveness of the program in terms of its targeting of beneficiaries, the flow of information from participating NGOs to beneficiaries on the need to recycle the seeds, and the level of recycling done at the end of the program. The empirical results suggest that the targeting method participating NGOs use inadvertently excludes relatively vulnerable households while including large proportions of relatively well-endowed households in the program. The choice of varieties to distribute is guided more by the ecological adaptability of available commercial seeds and less by preferences of beneficiaries. Notwithstanding the fact that seed selection information is critical in encouraging beneficiaries to recycle distributed seed, not all of them received it. In conclusion, it may be stated that the program undoubtedly contributed to increased food productivity by vulnerable households but its overall effectiveness could have been enhanced through (i) the involvement of the beneficiaries in the choice of types of seed to be distributed, (ii) better targeting of beneficiaries, and (iii) improved information flow between NGOs and beneficiaries.     

Spatial ability through engineering graphics education

Spatial ability has been confirmed to be of particular importance for successful engineering graphics education and to be a component of human intelligence that can be improved through instruction and training. Consequently, the creation and communication by means of graphics demand careful development of spatial skills provided by the balanced curricula based on the research results in multi disciplinary area. The approach to engineering graphics education had been transformed to meet spatial skills improvement even before significant and fast changes arose from the development of computer technology enabling the engineer powerful tools and techniques. The correlation and interference between new technologies widely introduced in engineering graphics education and spatial ability/skills, have initiated new studies to establish the basis of holistic engineering graphics education. This paper presents the overview of some efforts and possible answers resulting from intensive research into spatial ability and skills and their implementation in the conception of graphics education in engineering environment.