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Sample records for project-based science pbs

  1. Project-Based Science

    Science.gov (United States)

    Krajcik, Joe

    2015-01-01

    Project-based science is an exciting way to teach science that aligns with the "Next Generation Science Standards" ("NGSS"). By focusing on core ideas along with practices and crosscutting concepts, classrooms become learning environments where teachers and students engage in science by designing and carrying out…

  2. Project-Based Learning versus Textbook/Lecture Learning in Middle School Science

    Science.gov (United States)

    Main, Sindy

    2015-01-01

    As schools continue to become more diverse, it is important to look at science teaching methods that will meet the needs of all students. In this study, 172 students in a middle school in Northwestern Illinois were taught using two methods of teaching science. Half of the students were taught using project-based science (PBS) and the other half of…

  3. An Examination of Teacher Understanding of Project Based Science as a Result of Participating in an Extended Professional Development Program: Implications for Implementation

    Science.gov (United States)

    Mentzer, Gale A.; Czerniak, Charlene M.; Brooks, Lisa

    2017-01-01

    Project-based science (PBS) aligns with national standards that assert children should learn science by actively engaging in the practices of science. Understanding and implementing PBS requires a shift in teaching practices away from one that covers primarily content to one that prompts children to conduct investigations. A common challenge to…

  4. Doing the Project and Learning the Content: Designing Project-Based Science Curricula for Meaningful Understanding

    Science.gov (United States)

    Kanter, David E.

    2010-01-01

    Project-based science curricula can improve students' usable or meaningful understanding of the science content underlying a project. However, such curricula designed around "performances" wherein students design or make something do not always do this. We researched ways to design performance project-based science curricula (pPBSc) to better…

  5. Spiral and Project-Based Learning with Peer Assessment in a Computer Science Project Management Course

    Science.gov (United States)

    Jaime, Arturo; Blanco, José Miguel; Domínguez, César; Sánchez, Ana; Heras, Jónathan; Usandizaga, Imanol

    2016-01-01

    Different learning methods such as project-based learning, spiral learning and peer assessment have been implemented in science disciplines with different outcomes. This paper presents a proposal for a project management course in the context of a computer science degree. Our proposal combines three well-known methods: project-based learning,…

  6. How Teaching Science Using Project-Based Learning Strategies Affects the Classroom Learning Environment

    Science.gov (United States)

    Hugerat, Muhamad

    2016-01-01

    This study involved 458 ninth-grade students from two different Arab middle schools in Israel. Half of the students learned science using project-based learning strategies and the other half learned using traditional methods (non-project-based). The classes were heterogeneous regarding their achievements in the sciences. The adapted questionnaire…

  7. DEVELOPMENT OF SCIENCE PROCESS SKILLS STUDENTS WITH PROJECT BASED LEARNING MODEL- BASED TRAINING IN LEARNING PHYSICS

    Directory of Open Access Journals (Sweden)

    Ratna Malawati

    2016-06-01

    Full Text Available This study aims to improve the physics Science Process Skills Students on cognitive and psychomotor aspects by using model based Project Based Learning training.The object of this study is the Project Based Learning model used in the learning process of Computationa Physics.The method used is classroom action research through two learning cycles, each cycle consisting of the stages of planning, implementation, observation and reflection. In the first cycle of treatment with their emphasis given training in the first phase up to third in the model Project Based Learning, while the second cycle is given additional treatment with emphasis discussion is collaboration in achieving the best results for each group of products. The results of data analysis showed increased ability to think Students on cognitive and Science Process Skills in the psychomotor.

  8. The Use of Mobile Technologies in Project-Based Science: A Case Study

    Science.gov (United States)

    Avraamidou, Lucy

    2013-01-01

    The main aim of this study was to examine how a group of elementary students perceived their engagement in a project-based science intervention investigating the water quality of a local lake. The students collaborated with a scientist to conduct various experiments and used handheld computers to collect and analyze data in order to examine the…

  9. Global Warning: Project-Based Science Inspired by the Intergovernmental Panel on Climate Change

    Science.gov (United States)

    Colaianne, Blake

    2015-01-01

    Misconceptions about climate change are common, which suggests a need to effectively address the subject in the classroom. This article describes a project-based science activity in which students report on the physical basis, adaptations, and mitigation of this global problem, adapting the framework of the United Nations' Intergovernmental Panel…

  10. Computer Assisted Project-Based Instruction: The Effects on Science Achievement, Computer Achievement and Portfolio Assessment

    Science.gov (United States)

    Erdogan, Yavuz; Dede, Dinçer

    2015-01-01

    The purpose of this study is to compare the effects of computer assisted project-based instruction on learners' achievement in a science and technology course, in a computer course and in portfolio development. With this aim in mind, a quasi-experimental design was used and a sample of 70 seventh grade secondary school students from Org. Esref…

  11. Influences on teachers' curricular choices in project-based science classrooms

    Science.gov (United States)

    Laba, Karen Anne

    This descriptive research will present two case studies of experienced science teachers using project-based curricula in all or part of their secondary life science/biology courses. The purpose of this study is to reveal the underlying relationships between teachers' conceptions of the nature of science, their understanding of their role as science teachers and their expectations for appropriate and worthwhile student learning, and to describe the influence of these factors on their curricular choices within the project-based framework. Using a modification of Hewson, Kerby and Cook's (1995) Conceptions of Teaching Science protocol as a model, teachers' beliefs and intentions are classified and examined to identify organizing themes. Comparisons between teachers' beliefs and the actions they take in their project-based classroom are used to reveal relationships among the choices that result in students' learning experiences. Finally, the curricula presented by these two exemplary teachers are compared with the teaching standards and content goals defined in the National Science Education Standards (NRC, 1996). Recommendations for the application of the case study perspective of the evolution of learning experiences to reform efforts are offered to practitioners, policy makers, curriculum developers and teacher educators.

  12. Variables that impact the implementation of project-based learning in high school science

    Science.gov (United States)

    Cunningham, Kellie

    Wagner and colleagues (2006) state the mediocrity of teaching and instructional leadership is the central problem that must be addressed if we are to improve student achievement. Educational reform efforts have been initiated to improve student performance and to hold teachers and school leaders accountable for student achievement (Wagner et al., 2006). Specifically, in the area of science, goals for improving student learning have led reformers to establish standards for what students should know and be able to do, as well as what instructional methods should be used. Key concepts and principles have been identified for student learning. Additionally, reformers recommend student-centered, inquiry-based practices that promote a deep understanding of how science is embedded in the everyday world. These new approaches to science education emphasize inquiry as an essential element for student learning (Schneider, Krajcik, Marx, & Soloway, 2002). Project-based learning (PBL) is an inquiry-based instructional approach that addresses these recommendations for science education reform. The objective of this research was to study the implementation of project-based learning (PBL) in an urban school undergoing reform efforts and identify the variables that positively or negatively impacted the PBL implementation process and its outcomes. This study responded to the need to change how science is taught by focusing on the implementation of project-based learning as an instructional approach to improve student achievement in science and identify the role of both school leaders and teachers in the creation of a school environment that supports project-based learning. A case study design using a mixed-method approach was used in this study. Data were collected through individual interviews with the school principal, science instructional coach, and PBL facilitator. A survey, classroom observations and interviews involving three high school science teachers teaching grades 9

  13. The role of assessment infrastructures in crafting project-based science classrooms

    Science.gov (United States)

    D'Amico, Laura Marie

    In project-based science teaching, teachers engage students in the practice of conducting meaningful investigations and explanations of natural phenomena, often in collaboration with fellow students or adults. Reformers suggest that this approach can provide students with more profitable learning experiences; but for many teachers, a shift to such instruction can be difficult to manage. As some reform-minded teachers have discovered, classroom assessment can serve as a vital tool for meeting the challenges associated with project science activity. In this research, classroom assessment was viewed as an infrastructure that both students and teachers rely upon as a mediational tool for classroom activity and communications. The study explored the classroom assessment infrastructures created by three teachers involved in the Learning through Collaborative Visualization (CoVis) Project from 1993--94 to 1995--96. Each of the three teachers under study either created a new course or radically reformulated an old one in an effort to incorporate project-based science pedagogy and supporting technologies. Data in the form of interviews, classroom observations, surveys, student work, and teacher records was collected. From these data, an interpretive case study was developed for each course and its accompanying assessment infrastructure. A set of cross-case analyses was also constructed, based upon common themes that emerged from all three cases. These themes included: the assessment challenges based on the nature of project activity, the role of technology in the teachers' assessment infrastructure designs, and the influence of the wider assessment infrastructure on their course and assessment designs. In combination, the case studies and cross-case analyses describe the synergistic relationship between the design of pedagogical reforms and classroom assessment infrastructures, as well as the effectiveness of all three assessment designs. This work contributes to research

  14. Examining student conceptions of the nature of science from two project-based classrooms

    Science.gov (United States)

    Moss, David M.

    The purpose of this research was to develop descriptive accounts of precollege students' conceptions of the nature of science from two project-based classrooms, and track those conceptions over the course of an academic year. A model of the nature of science was developed and served as the criterion by which students' beliefs were evaluated. The model distinguishes between two major categories of science, the nature of the scientific enterprise and the nature of scientific knowledge. Five students were selected from each class and interviewed individually for 30-45 minutes each, six times over the year. Data from semi-structured, formal interviewing consisted of audio-recorded interviews which were transcribed verbatim. All passages were coded using codes which corresponded to the premises of the model of the nature of science. Passages in the transcripts were interpreted to develop a summary of the students' conceptions over the year. Qualitative methodologies, especially formal interviewing in conjunction with participant observation, were effective for uncovering students' conceptions of the nature of science, adding to the knowledge base in this field. The research design of the current study was a significant factor in explaining the inconsistencies seen between findings from this study and the literature. This study finds that participants at both classroom sites held fully formed conceptions of the nature of science for approximately 40 percent of the premises across the model. For two-thirds of the elements which comprise the premises, participants held full understandings. Participants held more complete understandings of the nature of scientific knowledge than the nature of the scientific enterprise. Most participants had difficulty distinguishing between science and non-science and held poor understandings of the role of questions in science. Students' beliefs generally remained unchanged over the year. When their conceptions did evolve, project-based

  15. Post secondary project-based learning in science, technology, engineering and mathematics

    OpenAIRE

    Ralph, Rachel A.

    2016-01-01

    Project-based learning (PjBL - to distinguish from problem-based learning - PBL) has become a recurrent practice in K-12 classroom environments. As PjBL has become prominent in K-12 classrooms, it has also surfaced in post-secondary institutions.  The purpose of this paper is to examine the research that has studied a variety of science, technology, engineering and mathematic subjects using PjBL in post-secondary classrooms. Eleven articles (including qualitative, quantitative and mixed metho...

  16. PBS Plus Facebook: The Old And New Communication Of Climate Science (Please "Like" And "Share" This Abstract)

    Science.gov (United States)

    Alley, R. B.; Haines-Stiles, G.; Akuginow, E.

    2012-12-01

    Traditional and innovative communications strategies were combined in "Earth: The Operators' Manual" (ETOM; writer & director Geoff Haines-Stiles, producer Erna Akuginow, presenter Richard Alley). We attempted both a clear and accessible presentation of some key essentials of current climate science and an experiment in new messaging and new media for outreach and education. ETOM is a 3-part TV series broadcast by PBS ("…one of the more interesting documentary series to come along in years", said the New York Times) and a 320 plus page tradebook, with 110 pages of footnotes referencing peer-reviewed science, published by Norton. But it's also a lively and growing Facebook page with a clear voice sharing positive examples of how renewable energy can reduce polluting emissions here in the US and worldwide, alongside headlines of climate science, and a website—relaunched for the 2012 Earth Day PBS broadcasts—where all three programs can be streamed, and teachers can register to download HD segments for classroom use. The TV programs were designed to offer a highly accessible statement of core climate science, literally explaining how ice cores show us today's climate is changing in ways not seen in the last 800,000 thousand years and why physics and chemistry let us know "It's Us" who are changing CO2 levels in the atmosphere through burning fossil fuels. But the project's outreach components also includes a "Science Pub" in a converted theater in Portland, where the audience consumes food, drink and climate science, and "Adventures of a Climate Scientist in the Age of Politics and Punditry," a dynamic live performance recorded for TV and the web. Messaging includes a Navy Rear Admiral in dress whites explaining why the Pentagon believes climate change is real, and scenes showing Marines and Army implementing solar technologies to enhance mission security and reduce their carbon bootprint. Similarly, outreach events at the North Carolina Museum of Natural

  17. The Development of Paranormal Belief Scale (PBS) for Science Education in the Context of Turkey

    Science.gov (United States)

    Sen, Mehmet; Yesilyurt, Ezgi

    2014-01-01

    Present study aims to translate and develop Paranormal Belief Questions (Rice, 2003) measuring students' non-scientific beliefs which threat science education. Original version of these questions was asked in Southern Focus Poll (1998). 17 questions about paranormal beliefs were administered to 114 university students from different departments.…

  18. Application of Model Project Based Learning on Integrated Science in Water Pollution

    Science.gov (United States)

    Yamin, Y.; Permanasari, A.; Redjeki, S.; Sopandi, W.

    2017-09-01

    The function of this research was to analyze the influence model Project Based Learning (PjBl) on integrated science about the concept mastery for junior high school students. Method used for this research constitutes the quasi of experiment method. Population and sample for this research are the students junior high school in Bandung as many as two classes to be experiment and control class. The instrument that used for this research is the test concept mastery, assessment questionnaire of product and the questionnaire responses of the student about learning integrated science. Based on the result of this research get some data that with accomplishment the model of PjBl. Learning authority of integrated science can increase the concept mastery for junior high school students. The highest increase in the theme of pollution water is in the concept of mixtures and the separation method. The students give a positive response in learning of integrated science for the theme of pollution of the water used model PjBL with questionnaire of the opinion aspect in amount of 83.5%, the anxiety of the students in amount of 95.5%, the profit learning model of PjBL in amount of 96.25% and profit learning of integrated science in amount of 95.75%.

  19. An Analysis of the Supports and Constraints for Scientific Discussion in High School Project-Based Science

    Science.gov (United States)

    Alozie, Nonye M.; Moje, Elizabeth Birr; Krajcik, Joseph S.

    2010-01-01

    One goal of project-based science is to promote the development of scientific discourse communities in classrooms. Holding rich high school scientific discussions is challenging, especially when the demands of content and norms of high school science pose challenges to their enactment. There is little research on how high school teachers enact…

  20. The Effect of Project-Based History and Nature of Science Practices on the Change of Nature of Scientific Knowledge

    Science.gov (United States)

    Çibik, Ayse Sert

    2016-01-01

    The aim of this study is to compare the change of pre-service science teachers' views about the nature of scientific knowledge through Project-Based History and Nature of Science training and Conventional Method. The sample of the study consists of two groups of 3rd grade undergraduate students attending teacher preparation program of science…

  1. Project-Based Learning as a Vehicle for Teaching Science at the University Level

    Science.gov (United States)

    Courtney, A. R.; Wade, P.

    2012-12-01

    In a typical science course learning is teacher directed. Students are presented with knowledge and concepts via textbooks and lecture and then given the opportunity to apply them. Project-based learning (PBL) creates a context and reason to learn information and concepts. In PBL, learning is student directed and teacher facilitated. Students take ownership of their learning by finding, evaluating and synthesizing information from a variety of resources and via interaction between each other. In PBL, the project is central rather than peripheral to the curriculum. It is not just an activity that provides examples, additional practice or applications of the course content, but rather, the vehicle through which major concepts are discovered. The PBL process requires students to do revision and reflection encouraging them to think about what and how they are learning. PBL projects also allow students to develop important life-work skills such as collaboration, communication and critical thinking within the discipline. We have employed PBL in both Liberal Arts courses for non-science majors and upper division courses for science students. Three examples will be discussed. The first will be the production of video documentaries in a non-science major course; the second, a student generated electronic textbook in a 300-level energy course for science students; and lastly, a student designed analysis project in a chemistry major capstone laboratory course. The product in each of these examples was used to deliver knowledge to others in the class as well as members of the public providing motivation for students to do high-quality work. In our examples, student documentaries are publicly screened as part of a university-wide Academic Excellence Showcase; the student generated electronic textbook is available for public use on the internet; and the results of the student designed analysis were communicated to the real-world clients via letters and reports. We will discuss

  2. The Effects of Project Based Learning on Undergraduate Students' Achievement and Self-Efficacy Beliefs towards Science Teaching

    Science.gov (United States)

    Bilgin, Ibrahim; Karakuyu, Yunus; Ay, Yusuf

    2015-01-01

    The purpose of this study is to investigate the effects of the Project-Based Learning (PBL) method on undergraduate students' achievement and its association with these students' self-efficacy beliefs about science teaching and pinions about PBL. The sample of the study consisted of two randomly chosen classes from a set of seven classes enrolled…

  3. Investigating the Quality of Project-Based Science and Technology Learning Environments in Elementary School: A Critical Review of Instruments

    Science.gov (United States)

    Thys, Miranda; Verschaffel, Lieven; Van Dooren, Wim; Laevers, Ferre

    2016-01-01

    This paper provides a systematic review of instruments that have the potential to measure the quality of project-based science and technology (S&T) learning environments in elementary school. To this end, a comprehensive literature search was undertaken for the large field of S&T learning environments. We conducted a horizontal bottom-up…

  4. Post secondary project-based learning in science, technology, engineering and mathematics

    Directory of Open Access Journals (Sweden)

    Rachel A Ralph

    2016-03-01

    Full Text Available Project-based learning (PjBL - to distinguish from problem-based learning - PBL has become a recurrent practice in K-12 classroom environments. As PjBL has become prominent in K-12 classrooms, it has also surfaced in post-secondary institutions.  The purpose of this paper is to examine the research that has studied a variety of science, technology, engineering and mathematic subjects using PjBL in post-secondary classrooms. Eleven articles (including qualitative, quantitative and mixed methods were included.  The format includes: an introduction and background (which defines PjBL and STEM, research methods, quality appraisal used, results, and a discussion, future research and a conclusion.  Two tables and two figures are included. In this paper, theoretical backgrounds and key terms were identified, followed by a literature review discussing four themes: content knowledge, interdisciplinary skills, collaboration and skill development for future education and careers.  Results suggested that there is a positive connection between content knowledge learning and PjBL in collaborative settings.  Additionally, some negative perceptions arose regarding teamwork situations.  Interdisciplinary skills were achieved, but quite limited in post-secondary classrooms.  PjBL and STEM were perceived to be important for future education and careers.  Future research needs to be completed and institutional curriculum changes informed by the results of this research need to occur to further explore interdisciplinary courses and the use of PjBL.

  5. Collaborative Project-Based Learning: An Integrative Science and Technological Education Project

    Science.gov (United States)

    Baser, Derya; Ozden, M. Yasar; Karaarslan, Hasan

    2017-01-01

    Background: Blending collaborative learning and project-based learning (PBL) based on Wolff (2003) design categories, students interacted in a learning environment where they developed their technology integration practices as well as their technological and collaborative skills. Purpose: The study aims to understand how seventh grade students…

  6. Applying the Science of Science Communication to Climate Change and Clean Energy: Lessons Learned from the NSF- and PBS-supported "Earth: The Operators' Manual"

    Science.gov (United States)

    Haines-Stiles, G.; Akuginow, E.; Sanford, C.

    2014-12-01

    Yale legal scholar and professor of psychology Dan Kahan has criticized the climate change science community for not applying what's known about effective communications strategies to topics with potentially controversial content. "Earth: The Operators' Manual," funded by NSF's Informal Science Education program and appearing on PBS was hosted by Penn State geoscientist Richard Alley. From the initial proposal forward into airing on public television in 2011 and 2012, ETOM aimed to be authoritative and apolitical while still being engaging to general audiences. Based on social scientific insights from project Advisor, Suzanne Moser, and others, ETOM aimed to avoid "climate porn" scare tactics and over-used footage, and to enlist a diverse group of "messengers" in addition to Alley. An important design criterion was to give equal time to clean energy solutions while pulling no punches as to the consensus findings of leading climate scientists. With the ETOM project now completed and final reports submitted to NSF, what results can be shared to inform future efforts? And how did ETOM compare in audience impact with other major media efforts such as Al Gore's "An Inconvenient Truth" or Showtime's more recent "Years of Living Dangerously"? Results reported draw on the external evaluation by Rockman Et Al, and include both quantitative and qualitative data. Key findings are the importance of including Texan ranchers enthusiastic about wind power alongside Navy Admirals adamant that climate change is human-caused and Marines implementing solar energy to reduce casualties incurred while transporting fossil fuels. In-person presentations by Alley and others at science centers served as de facto focus groups for scripting the TV programs, along with actual focus groups convened by Rockman. The 3rd program, ENERGY QUEST USA, documented 5 quite different communities, from Alaska to Forth Worth, Baltimore, Portland and Kansas, all using competition, local values, and economic

  7. The effects of topic choice in project-based instruction on undergraduate physical science students' interest, ownership, and motivation

    Science.gov (United States)

    Milner-Bolotin, Marina

    2001-07-01

    Motivating nonscience majors in science and mathematics studies became one of the most interesting and important challenges in contemporary science and mathematics education. Therefore, designing and studying a learning environment, which enhances students' motivation, is an important task. This experimental study sought to explore the implications of student autonomy in topic choice in a project-based Physical Science Course for nonscience majors' on students' motivational orientation. It also suggested and tested a model explaining motivational outcomes of project-based learning environment through increased student ownership of science projects. A project, How Things Work, was designed and implemented in this study. The focus of the project was application of physical science concepts learned in the classroom to everyday life situations. Participants of the study (N = 59) were students enrolled in three selected sections of a Physical Science Course, designed to fulfill science requirements for nonscience majors. These sections were taught by the same instructor over a period of an entire 16-week semester at a large public research university. The study focused on four main variables: student autonomy in choosing a project topic, their motivational orientation, student ownership of the project, and the interest in the project topic. Achievement Goal Orientation theory became the theoretical framework for the study. Student motivational orientation, defined as mastery or performance goal orientation, was measured by an Achievement Goal Orientation Questionnaire. Student ownership was measured using an original instrument, Ownership Measurement Questionnaire, designed and tested by the researchers. Repeated measures yoked design, ANOVA, ANCOVA, and multivariate regression analysis were implemented in the study. Qualitative analysis was used to complement and verify quantitative results. It has been found that student autonomy in the project choice did not make a

  8. Development of a science project based on the use of several intelligences

    Directory of Open Access Journals (Sweden)

    Gallegos Reséndiz, Cut

    2013-01-01

    Full Text Available Solve and create problems are characteristic of an intelligent and creative mind. From a practical sense, intelligence procedures and leads to correct results but creativity allow us to innovate on procedures, interpretation of results and generated products. This project combines science and art, aiming to promote intelligence and creativity in students in the second grade of primary school. The work is part of the study of general aspects of the biology of insects in various learning environments. The results indicate a process of understanding the basic structures of insects, the biological sense of communication sounds and movements of the basic elements of music making, of how an orchestra is organized and a dance and especially the resolution of problems related to science and art.

  9. Combining Project-based Instruction, Earth Science Content, and GIS Technology in Teacher Professional Development: Is this Holistic Approach Sustainable?

    Science.gov (United States)

    Rubino-Hare, L.; Bloom, N.; Claesgens, J.; Fredrickson, K.; Henderson-Dahms, C.; Sample, J. C.

    2012-12-01

    From 2009-2011, with support from the National Science Foundation (ITEST, DRL-0929846) and Science Foundation Arizona (MSAG-0412-09), educators, geologists and geographers at Northern Arizona University (NAU) partnered to offer professional development for interdisciplinary teams of secondary and middle school teachers with a focus on project-based instruction (PBI) using geospatial technologies (GST). While participating in professional development teachers received support and were held accountable to NAU staff. They implemented activities and pedagogical strategies presented, increased knowledge, skills, and confidence teaching with project-based instruction integrating GST, and their students demonstrated learning gains. Changes in student understanding are only observed when teachers continue to implement change, so the question remained: did these changes in practice sustain after official project support ended? In order to determine what, if anything, teachers sustained from the professional development and the factors that promoted or hindered sustained use of teaching with GST and PBI, data were collected one to two years following the professional development. Research questions included a) what pedagogical practices did teachers sustain following the professional learning experiences? and b) what contexts were present in schools that supported or limited the use of geospatial technologies as a teaching and learning tool? Findings from this study indicate that teachers fall into three categories of sustaining implementation - reformed implementers, mechanical implementers and non-implementers. School context was less of a factor in level of implementation than teachers' beliefs and philosophy of teaching and teachers' understanding of technology integration (teaching with technology vs. teaching technology). Case studies of teacher experiences will be presented along with implications for future professional development.

  10. Learning Styles of Science and Engineering Students in Problem and Project Based Education

    DEFF Research Database (Denmark)

    Kolmos, Anette; Holgaard, Jette Egelund

    2008-01-01

    At the Faculty of Engineering and Science at Aalborg University, Denmark, process skills are an integrated part of the curriculum objectives. During the first year programme, a special course in Collaboration, Learning and Project Management (CLP) is given to develop those skills. In order...... to develop students’ learning and the CLP-course, the Felder-Soloman Index of Learning Styles (ILS®) has been used in that course and data has been collected to investigate whether some learning style preferences are more conspicuous that others in a problem based learning environment. The results show, more...... pronounced than similar studies, that the first year engineering students at Aalborg University are considerable more active than reflective. This results leads to a discussion of whether reflection and conceptualization should be facilitated further in the curriculum to balance the students learning style...

  11. The perceptions of pre-service and in-service teachers regarding a project-based STEM approach to teaching science.

    Science.gov (United States)

    Siew, Nyet Moi; Amir, Nazir; Chong, Chin Lu

    2015-01-01

    Whilst much attention has focused on project-based approaches to teaching Science, Technology, Engineering and Mathematics (STEM) subjects, little has been reported on the views of South-East Asian science teachers on project-based STEM approaches. Such knowledge could provide relevant information for education training institutions on how to influence innovative teaching of STEM subjects in schools. This article reports on a study that investigated the perceptions of 25 pre-service and 21 in-service Malaysian science teachers in adopting an interdisciplinary project-based STEM approach to teaching science. The teachers undertook an eight hour workshop which exposed them to different science-based STEM projects suitable for presenting science content in the Malaysian high school science syllabus. Data on teachers' perceptions were captured through surveys, interviews, open-ended questions and classroom discussion before and at the end of the workshop. Study findings showed that STEM professional development workshops can provide insights into the support required for teachers to adopt innovative, effective, project-based STEM approaches to teaching science in their schools.

  12. Holistic Approach to Secondary Earth Science Teacher Professional Development: the Triad of Project-based Instruction, Earth Science Content, and GIS Technology

    Science.gov (United States)

    Rubino-Hare, L.; Sample, J. C.; Fredrickson, K.; Claesgens, J.; Bloom, N.; Henderson-Dahms, C.; Manone, M.

    2011-12-01

    We have provided two years of professional development for secondary and middle school teachers with a focus on project-based instruction (PBI) using GIS. The EYE-POD project (funded by NSF-ITEST) involved pairs of teachers from Arizona and the surrounding region in two-week institutes during Summer, 2010, and an advanced institute in Summer, 2011. The NAz-POD project (funded by Arizona Department of Education and administered by Science Foundation Arizona) provided similar PD experiences, but the institutes occurred during weekends in the academic year. The institutes were led by a team with expertise in Earth science content, professional development and pedagogy, and GIS. The teachers developed learning modules using the project based learning instructional model. Pedagogy, content, and GIS skills were combined throughout the professional development activities. Academic year follow up by NAU personnel included classroom observations and technical support. For assessing student work we provided a rubric, but learned that teachers were not prepared to assess GIS products in order to determine the level of student understanding. In year two of the project we incorporated strategies for assessment of student products into the professional development. Teacher-participants and their students completed several pre- and post- assessments. Teacher assessments included a geospatial performance assessment, classroom observations, and content tests. Student data collection included attitude and efficacy questionnaires, content tests, and authentic assessments including products using GIS. Content tests were the same for teachers and students and included spatial reasoning, data analysis, and Earth science content. Data was also collected on teacher perception of professional development delivery and self-reported confidence in teaching with PBI and geospatial technology. Student assessments show that improvement occurred in all areas on the content test. Possible factors

  13. The Ripple Effect: Exploring How a Joint Science Specialist/TOSA Can Change Classroom Teachers' Instructional Practices through Project-Based Learning

    Science.gov (United States)

    Gradias, Jean

    In 2013, California became one of the first states to adopt the rigorous Next Generation Science Standards (NGSS). However, the current state of science instruction does not support the conceptual shifts of the NGSS, which call for consistent science instruction K-12, increased inquiry, subject integration, as well as science instruction that connects students to their communities and their world. Therefore, teachers are in need of instructional support for science teaching that can enable them to achieve these higher expectations. This dissertation explored whether implementing a Project-Based Learning (PBL)-centered science specialist changed classroom teachers' frequency of science instruction and use of instructional strategies that support NGSS science delivery. In addition, this study examined how providing a PBL science specialist supported teachers in their comfort with using these more rigorous instructional strategies. Five elementary teachers participated in an action research project conducted over the course of a school year. The frequency with which teachers used the following instructional strategies was analyzed: connecting science to real world phenomena, accessing community resources, integrating science into other subject areas, and using inquiry in science instruction. Quantitative and qualitative data revealed that a PBL science specialist does support classroom teachers in implementing teaching practices aligned to the conceptual shifts implicated by the NGSS; however, individual growth rates varied by instructional strategy. The results of this study provide a foundation for the legitimacy of utilizing a PBL-focused science specialist to support teachers in shifting their instructional practices in order to achieve the Next Generation Science Standards.

  14. Teacher Perceptions of Their Curricular and Pedagogical Shifts: Outcomes of a Project-Based Model of Teacher Professional Development in the Next Generation Science Standards

    OpenAIRE

    David J. Shernoff; David J. Shernoff; Suparna Sinha; Denise M. Bressler; Dawna Schultz

    2017-01-01

    In this study, we conducted a model of teacher professional development (PD) on the alignment of middle and high school curricula and instruction to the Next Generation Science Standards (NGSSs), and evaluated the impact of the PD on teacher participants’ development. The PD model included a 4-day summer academy emphasizing project-based learning (PBL) in the designing of NGSS-aligned curricula and instruction, as well as monthly follow-up Professional Learning Community meetings throughout t...

  15. Effects of 3D Printing Project-based Learning on Preservice Elementary Teachers' Science Attitudes, Science Content Knowledge, and Anxiety About Teaching Science

    Science.gov (United States)

    Novak, Elena; Wisdom, Sonya

    2018-05-01

    3D printing technology is a powerful educational tool that can promote integrative STEM education by connecting engineering, technology, and applications of science concepts. Yet, research on the integration of 3D printing technology in formal educational contexts is extremely limited. This study engaged preservice elementary teachers (N = 42) in a 3D Printing Science Project that modeled a science experiment in the elementary classroom on why things float or sink using 3D printed boats. The goal was to explore how collaborative 3D printing inquiry-based learning experiences affected preservice teachers' science teaching self-efficacy beliefs, anxiety toward teaching science, interest in science, perceived competence in K-3 technology and engineering science standards, and science content knowledge. The 3D printing project intervention significantly decreased participants' science teaching anxiety and improved their science teaching efficacy, science interest, and perceived competence in K-3 technological and engineering design science standards. Moreover, an analysis of students' project reflections and boat designs provided an insight into their collaborative 3D modeling design experiences. The study makes a contribution to the scarce body of knowledge on how teacher preparation programs can utilize 3D printing technology as a means of preparing prospective teachers to implement the recently adopted engineering and technology standards in K-12 science education.

  16. Impact of Project-Based Curriculum Materials on Student Learning in Science: Results of a Randomized Controlled Trial

    Science.gov (United States)

    Harris, Christopher J.; Penuel, William R.; D'Angelo, Cynthia M.; DeBarger, Angela Haydel; Gallagher, Lawrence P.; Kennedy, Cathleen A.; Cheng, Britte Haugen; Krajcik, Joseph S.

    2015-01-01

    The "Framework for K-12 Science Education" (National Research Council, 2012) sets an ambitious vision for science learning by emphasizing that for students to achieve proficiency in science they will need to participate in the authentic practices of scientists. To realize this vision, all students will need opportunities to learn from…

  17. The role of project-based learning in the "Political and social sciences of the environment" curriculum at Nijmegen University

    NARCIS (Netherlands)

    Leroy, P.; Bosch, van den H.; Ligthart, S.S.H.

    2001-01-01

    Since the end of 1996, teachers at the Faculty of Policy Sciences at Nijmegen University, The Netherlands, have been working on a new educational programme called "Political and Social Sciences of the Environment" (PSSE). In fact, the PSSE curriculum builds on the Environmental Policy Sciences

  18. Analysis of the ability of junior high school students’ performance in science in STEM project-based learning

    Science.gov (United States)

    Suryana, A.; Sinaga, P.; Suwarma, I. R.

    2018-05-01

    The challenges in 21st century demands the high competitiveness. The way of thinking ability, determine how it work ability and choose instrument be part of the skills will need in the 21st century. The competence it can be supported by learning involving the student performance skills. Based on the preliminary studies at one junior high school in Bandung found that the learning involving of performance skill is low.This is supported by data from respondent in received the opportunity to make devise a sketch in of learning especially based on practices or projects, the results are 75 % students said rarely and 18,75 % students said never. In addition seen also how the student activities in project based learning in class the results stated that 68,75 % of students said less, and 6.25 % of students said never. Therefore, we did a result to uncover profile performance on the design process and the performance process of junior high school student performances to the matter optical by using STEM project based learning. From this result. From the research obtained the average score classes in the activities of the design process is as much as 2,49 or dipersentasikan become 62,41 % are in the good category and the average score classes in the process of the performance of activities receive is 3,13 or 78,28 % are in the good category.

  19. Using Project-Based Data in Physics to Examine Television Viewing in Relation to Student Performance in Science

    Science.gov (United States)

    Espinoza, Fernando

    2009-10-01

    Mass media, particularly television, influence public conceptions and attitudes toward learning science. The discovery of an original method that does not rely on self-reported viewing habits to measure the impact of television on students' performance in science arose from a study of a unit on electricity in a Physics course. In determining the number of television sets at home and the number of hours of operation, data emerged that allowed an investigation of associations between each of these variables and student performance in physics. A negative impact on performance was found in its consistent decrease as both the number of sets and the time the sets are on increase. These results provide dramatic independent confirmation of the negative impact of television viewing on achievement determined through meta-analysis of many studies, and are also consistent with those in the literature at large, particularly from the Third International Mathematics and Science Study, and the National Assessment of Educational Progress. Furthermore, the totally `blind' participation of the subjects lends a degree of authenticity rarely found in a classically designed study. The findings impact scientific literacy, since performance in science and conceptions of science and scientists, are all inextricably linked.

  20. How Much Carbon Is in the Forest? A Project-Based Science Investigation of Trees' Role in Offsetting Global Warming

    Science.gov (United States)

    Penniman, Leah

    2011-01-01

    At the start of an integrated Algebra I and Environmental Science class, students were presented with the following challenge: "How much carbon is stored in the Normanskill Preserve?" They were told they had one month to investigate and present their results, and asked, "What do you need to begin?" This hook served to introduce…

  1. Project-based learning strategy, supported by virtual mediations and computer tools in a poultry production course: case study in Agricultural Sciences

    Directory of Open Access Journals (Sweden)

    Luis Díaz S

    2017-12-01

    Full Text Available The project-based learning strategy, supported by virtual mediations and computer tools, was applied to 42 students of a program of Animal Science in the course poultry Production in which the degree of familiarization, academic productivity, e-mail asynchronous mediation, the domain of the excel spreadsheet and the appreciation against the implemented methodology. The results showed that 100% of the students did not know the learning strategy and showed fears at the beginning of the activity. The final grades obtained (4.44 ± 0.14, 38.09%; 3.67 ± 0.09; 38.09%; 2.8, 19.05%, delivered products and degree of achievement (100%, 31 students; 88.88%, 5 students; 77.77%, 3 students; 55.55%, 3 students were influenced by the degree of mastery of the spreadsheet (8 students showed mastery, 26 a basic level to elementary and scarce, the rest and the registered participation level. It was found that the strategy generated motivation in the students reflected in the accomplishment of the goals and objectives drawn at the beginning of the course, increased the student-teacher interaction and reached a high academic performance (final grades ≥3.7 in the majority of the participants (73.8%.

  2. A Cross-Cultural Study of the Effect of a Graph-Oriented Computer-Assisted Project-Based Learning Environment on Middle School Students' Science Knowledge and Argumentation Skills

    Science.gov (United States)

    Hsu, P.-S.; Van Dyke, M.; Chen, Y.; Smith, T. J.

    2016-01-01

    The purpose of this mixed-methods study was to explore how seventh graders in a suburban school in the United States and sixth graders in an urban school in Taiwan developed argumentation skills and science knowledge in a project-based learning environment that incorporated a graph-oriented, computer-assisted application (GOCAA). A total of 42…

  3. Teacher Perceptions of Their Curricular and Pedagogical Shifts: Outcomes of a Project-Based Model of Teacher Professional Development in the Next Generation Science Standards

    Directory of Open Access Journals (Sweden)

    David J. Shernoff

    2017-06-01

    Full Text Available In this study, we conducted a model of teacher professional development (PD on the alignment of middle and high school curricula and instruction to the Next Generation Science Standards (NGSSs, and evaluated the impact of the PD on teacher participants’ development. The PD model included a 4-day summer academy emphasizing project-based learning (PBL in the designing of NGSS-aligned curricula and instruction, as well as monthly follow-up Professional Learning Community meetings throughout the year providing numerous opportunities for teachers to develop and implement lesson plans, share results of lesson writing and implementation (successes and challenges, provide mutual feedback, and refine curricula and assessments. Following the summer academy, six female teachers were interviewed about their current conceptualizations of NGSS, the extent of curricular shifts made that are required by NGSS, their self-perceptions regarding their level of accomplishment in curriculum writing, and the benefits of the PD in reaching their goals related to NGSS. Interviews were supplemented with an analysis of lesson plans written while participating in the PD program. The interviewed teachers suggested that they had made important conceptual and pedagogical shifts required by NGSS as they participated in the PD, and also noted a variety of challenges as they made this shift. While all teachers were relative novices at NGSS curriculum writing before the PD, most of the teachers interviewed felt that they had achieved the status of an “accomplished novice” following the summer academy. An analysis of their written lessons suggested a great range in the extent to which teachers effectively applied their understanding of NGSS to write lessons aligned to NGSS. Interviewed teachers believed that the PD model was helpful to their development as science teachers, and all reported that there were no aspects of the PD that were not helpful. Even though most teachers

  4. Teacher Perceptions of Their Curricular and Pedagogical Shifts: Outcomes of a Project-Based Model of Teacher Professional Development in the Next Generation Science Standards.

    Science.gov (United States)

    Shernoff, David J; Sinha, Suparna; Bressler, Denise M; Schultz, Dawna

    2017-01-01

    In this study, we conducted a model of teacher professional development (PD) on the alignment of middle and high school curricula and instruction to the Next Generation Science Standards (NGSSs), and evaluated the impact of the PD on teacher participants' development. The PD model included a 4-day summer academy emphasizing project-based learning (PBL) in the designing of NGSS-aligned curricula and instruction, as well as monthly follow-up Professional Learning Community meetings throughout the year providing numerous opportunities for teachers to develop and implement lesson plans, share results of lesson writing and implementation (successes and challenges), provide mutual feedback, and refine curricula and assessments. Following the summer academy, six female teachers were interviewed about their current conceptualizations of NGSS, the extent of curricular shifts made that are required by NGSS, their self-perceptions regarding their level of accomplishment in curriculum writing, and the benefits of the PD in reaching their goals related to NGSS. Interviews were supplemented with an analysis of lesson plans written while participating in the PD program. The interviewed teachers suggested that they had made important conceptual and pedagogical shifts required by NGSS as they participated in the PD, and also noted a variety of challenges as they made this shift. While all teachers were relative novices at NGSS curriculum writing before the PD, most of the teachers interviewed felt that they had achieved the status of an "accomplished novice" following the summer academy. An analysis of their written lessons suggested a great range in the extent to which teachers effectively applied their understanding of NGSS to write lessons aligned to NGSS. Interviewed teachers believed that the PD model was helpful to their development as science teachers, and all reported that there were no aspects of the PD that were not helpful. Even though most teachers obtained a basic

  5. Monitoring system for OpenPBS environment

    Energy Technology Data Exchange (ETDEWEB)

    Kolosov, V. [ITEP, Moscow (Russian Federation)]. E-mail: victor.kolosov@itep.ru; Lublev, Y. [ITEP, Moscow (Russian Federation); Makarychev, S. [ITEP, Moscow (Russian Federation)

    2004-11-21

    The OpenPBS batch system is widely used in the HEP community. The Open PBS package has a set of tools to check the current status of the system. This information is useful, but it is not sufficient enough for resource accounting and planning. As a solution for this problem, we developed a monitoring system which parses the logfiles from OpenPBS and stores the information into a SQL database (PostgreSQL). This allows us to analyze the data in many different ways using SQL queries. The system was used in ITEP during the last two years for batch farm monitoring.

  6. The Ripple Effect: Exploring How a Joint Science Specialist/TOSA Can Change Classroom Teachers' Instructional Practices through Project-Based Learning

    Science.gov (United States)

    Gradias, Jean

    2017-01-01

    In 2013, California became one of the first states to adopt the rigorous Next Generation Science Standards (NGSS). However, the current state of science instruction does not support the conceptual shifts of the NGSS, which call for consistent science instruction K-12, increased inquiry, subject integration, as well as science instruction that…

  7. PBS in the service of ecology

    International Nuclear Information System (INIS)

    Stiegel, J.

    1999-01-01

    In this paper the activities of PBS Banska Bystrica, Ltd., in the service ecology are presented. PBS is fundamentally oriented toward repairs to and maintenance of original products of Prvni brnenska strojirna, including spare parts, as well as modernization and ecologization of heat-energy operations using low-emission combustion equipment, cogeneration units for steam-gas processes and high efficient technological process control systems. In connection with company's profile the prospectus expressed with a sum of 80 million Slovak crowns in orders accepted for 1998 was exceed by 15 million Slovak crowns and despite a bad situation on the Slovak financial market the company is functioning in the first year of its activity without credits. In the perspective by 2000 PBS plans to obtain 200 million Slovak crowns worth orders

  8. Reinforcement effect of poly(butylene succinate) (PBS)-grafted cellulose nanocrystal on toughened PBS/polylactic acid blends.

    Science.gov (United States)

    Zhang, Xuzhen; Zhang, Yong

    2016-04-20

    Poly(butylene succinate) (PBS)/polylactic acid (PLA) blends modified with dicumyl peroxide (DCP) were reinforced by PBS-g-cellulose nanocrystal (CNC) through melt mixing. PBS-g-CNC was prepared through in situ polymerization and its structure was confirmed by FTIR, (13)C NMR, XPS and GPC analysis after saponification. The morphological analysis of PBS/PLA/PBS-g-CNC composites before and after etched by CH2Cl2 shows that the addition of DCP and PBS-g-CNC could decrease the size of PBS as a dispersed phase in PLA matrix and improve the dispersion of PBS-g-CNC in both PBS and PLA phases, which could affect the crystallization and mechanical properties of composites. The crystallinity of PLA α'-phase crystal in PBS/PLA/PBS-g-CNC composites is increased obviously by the addition of PBS-g-CNC, leading to an increase of the crystallinity of the composites. PBS/PLA blends modified by DCP have high Notched Izod impact strength and moduli, and the values are increased by the addition of PBS-g-CNC. Both storage modulus and glass translation temperature of PBS/PLA blend are increased by DCP and PBS-g-CNC, which is proved by DMA results, showing a weak molecular segment mobility of PBS/PLA matrix. The addition of DCP decreases the crystallization temperature and crystallinity of PBS/PLA composite, but increases the thermal stability of composites, mostly because of the crosslink effect of DCP on PBS/PLA matrix. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Expanding educational access and opportunities: The globalization and foreign direct investment of multinational corporations and their influence on STEM, project-based learning and the national science and technology fair in schools in Costa Rica

    Science.gov (United States)

    Valdez, Joaquin G.

    The purpose of this qualitative study was to examine the influence of globalization and the foreign direct investment (FDI) of multinational corporations (MNCs) on the curriculum in schools in Costa Rica. The study focused primarily on Science, Technology, Engineering and Mathematics (STEM), Project-Based Learning (PBL), 21st century skills, and the national science and technology fair. The high influx of MNCs such as Intel has changed the global and educational culture of the country increasing the number of knowledge-based workers in Costa Rica. As a result, policy changes have been instituted in education to mirror the demands of sustaining the country's global economy. This study was supported by the creation of three research questions that would attempt to answer 1) the extent that teachers implementing STEM curriculum trace their practices back to policy, globalization, and multinational corporations as well as the extent to which the economic growth of Costa Rica and STEM education are related, 2) how mandating the national science and technology fair has influenced 21st century skills through project-based learning and the use of technology by teachers and its impact on curriculum and instruction, and 3) how has the national science and technology fair policy changed the value of STEM education for students, teachers, and educational leaders. To further understand the outcome of this study, four theoretical frameworks were applied that included, Spring's theory of world educational culture, Friedman's world flatteners, Wagner's 21st century skills and partnerships for 21st century skills, and Slough and Milam's STEM project-based learning theoretical framework. Each framework was applied to support the changes to the educational system; survival skills necessary to compete in the global job market; application of 21st century skills in the classroom and in the science projects students created. A research team comprised of 14 doctoral students, led by Dr

  10. Promoting Learning by Inquiry Among Undergraduates in Soil Sciences: Scaffolding From Project-based Courses to Student-Staff Research Grants by the National Research Agency in Oman

    Science.gov (United States)

    Al-Ismaily, Said; Kacimov, Anvar; Al-Maktoumi, Ali

    2016-04-01

    Three strategies in a soil science undergraduate programme with inquiry-based learning (IBL) principles at Sultan Qaboos University, Oman, are presented. The first strategy scaffolds courses into three phases: with direct instructional guidance, structured IBL, and finally, guided to open IBL. The second strategy involves extra-curricular activities of undergraduates, viz. conducting workshops on soils for pupils in grades 7-9 with their teachers. The third strategy promotes the teaching-research nexus through collaboration between the undergraduates and faculty within a student-supporting, government-funded programme through 1-year long research grants of up to 5,500 US/project. The efficiency of the strategies was evaluated by students' evaluations of courses and instructors and questionnaire-based surveys. Statistics of students' responses in teaching evaluations of IBL courses showed a significantly higher level of satisfaction compared with regular courses taught in the department and college. In surveys of other constituencies of the program, viz. the secondary schools, more than 90% of respondents "agreed" or "strongly agreed" that they had learned new information/secrets about soils. The indicators of success in the third strategy are: winning a highly competitive grant and, moreover, earning an even more competitive annual national award for the best executed research project. The two top graduates of the IBL soil programme progressed into the MSc programme with the university and national scholarships. Key words: inquiry based learning, soil science undergraduate program, scaffold of courses, outreach activities, teaching-research nexus, evaluation of program's efficiency

  11. PROJECT-BASED LEARNING IN CONSUMER SCIENCES ...

    African Journals Online (AJOL)

    user

    One of the teaching-learning strategies that may .... together in small groups, while sharing ideas ... lecturer and learner when scaffolding pedagogy, .... their roles, interaction and access to resources. ... When using the measure of practical.

  12. Review on PCL, PBS, and PCL/PBS blends containing carbon nanotubes

    Directory of Open Access Journals (Sweden)

    T. P. Gumede

    2018-06-01

    Full Text Available Biodegradable polymers received considerable attention due to their contribution in the reduction of environmental concerns and the realization that global petroleum resources are finite. The development of double crystalline biobased blends such as poly(ε-caprolactone (PCL and poly(butylene succinate (PBS are particularly interesting because each component has an influence on the crystallization behaviour of the other component, and thus influences the strength and mechanical properties of a polymer blend. The lack of miscibility between PCL and PBS constitutes a bottleneck, and efforts have been made to improve the miscibility through the inclusion of copolymers. Having realized that incorporating conductive nanofillers such as carbon nanotubes (CNTs, (especially when the CNTs are functionalized or used as a masterbatch i.e., polycarbonate/MWCNTs masterbatch, into biopolymer matrices, can enhance the thermal and mechanical properties, as well as electrical and thermal conductivity, a lot of research was aimed at the production of bionanocomposites. This review paper discusses the properties of PCL, PBS, their blends, and their CNTs containing nanocomposites.

  13. Staying True to Our PBS Roots in a Changing World

    Science.gov (United States)

    Kincaid, Don

    2018-01-01

    The field of Positive Behavior Support (PBS) has grown and changed significantly in the past 25 years and should be expected to continue that trend for the next 25 years. These changes cannot always be predicted, but they can be managed by considering some current changes to the definition of PBS (Kincaid et al., 2016). This paper discussed how…

  14. Facile synthesis of organically capped PbS nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nejo, Ayorinde O.; Nejo, Adeola A.; Pullabhotla, Rajasekhar V.S.R. [Department of Chemistry, University of Zululand, Private Bag X1001, Kwadlangezwa (South Africa); Revaprasadu, Neerish, E-mail: nrevapra@pan.uzulu.ac.za [Department of Chemistry, University of Zululand, Private Bag X1001, Kwadlangezwa (South Africa)

    2012-10-05

    Highlights: Black-Right-Pointing-Pointer Hexadecylamine and tri-n-octylphosphine oxide capped PbS nanoparticles have been synthesized. Black-Right-Pointing-Pointer By varying the reaction conditions various morphologies were formed. Black-Right-Pointing-Pointer The formation of the anisotropic particles is due to different growth mechanisms. - Abstract: PbS nanocubes and nanorods were successfully synthesized through a facile route using hexadecylamine (HDA) and tri-n-octylphosphine oxide (TOPO) as surfactants. The structure and morphology of the as-prepared PbS nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM. The morphology of the PbS was influenced by the variation in lead source and organic surfactant. Particles in the shape of spheres, perfect cubes and rods were obtained by variation in reaction conditions. A possible growth mechanism to explain the formation of these PbS nanocubes and nanorods is also discussed.

  15. Structural characterization of chemically deposited PbS thin films

    International Nuclear Information System (INIS)

    Fernandez-Lima, F.A.; Gonzalez-Alfaro, Y.; Larramendi, E.M.; Fonseca Filho, H.D.; Maia da Costa, M.E.H.; Freire, F.L.; Prioli, R.; Avillez, R.R. de; Silveira, E.F. da; Calzadilla, O.; Melo, O. de; Pedrero, E.; Hernandez, E.

    2007-01-01

    Polycrystalline thin films of lead sulfide (PbS) grown using substrate colloidal coating chemical bath depositions were characterized by RBS, XPS, AFM and GIXRD techniques. The films were grown on glass substrates previously coated with PbS colloidal particles in a polyvinyl alcohol solution. The PbS films obtained with the inclusion of the polymer showed non-oxygen-containing organic contamination. All samples maintained the Pb:S 1:1 stoichiometry throughout the film. The amount of effective nucleation centers and the mean grain size have being controlled by the substrate colloidal coating. The analysis of the polycrystalline PbS films showed that a preferable (1 0 0) lattice plane orientation parallel to the substrate surface can be obtained using a substrate colloidal coating chemical bath deposition, and the orientation increases when a layer of colloid is initially dried on the substrate

  16. Orthogonality Measurement for Homogenous Projects-Bases

    Science.gov (United States)

    Ivan, Ion; Sandu, Andrei; Popa, Marius

    2009-01-01

    The homogenous projects-base concept is defined. Next, the necessary steps to create a homogenous projects-base are presented. A metric system is built, which then will be used for analyzing projects. The indicators which are meaningful for analyzing a homogenous projects-base are selected. The given hypothesis is experimentally verified. The…

  17. A Project-Based Biologically-Inspired Robotics Module

    Science.gov (United States)

    Crowder, R. M.; Zauner, K.-P.

    2013-01-01

    The design of any robotic system requires input from engineers from a variety of technical fields. This paper describes a project-based module, "Biologically-Inspired Robotics," that is offered to Electronics and Computer Science students at the University of Southampton, U.K. The overall objective of the module is for student groups to…

  18. Teacher Perceptions of Project Based Learning in the Secondary Classroom

    Science.gov (United States)

    MacMath, Sheryl; Sivia, Awneet; Britton, Vandy

    2017-01-01

    This study examines teacher perceptions of their experiences with Project Based Learning (PBL) at a secondary school in Western Canada. This PBL initiative included English language arts, mathematics, science, and digital literacy courses and all the grade nines at this large secondary school. This article reports on two teacher focus group…

  19. Assessment of Project-Based Learning in a MECHATRONICS Context

    Science.gov (United States)

    Doppelt, Yaron

    2005-01-01

    Project-based learning (PBL) that has authenticity in the pupils' world enables the teaching of science and technology to pupils from a variety of backgrounds. PBL has the potential to enable pupils to research, plan, design, and reflect on the creation of technological projects (Doppelt, 2000). Engineering education, which is common in Israel,…

  20. Effective Teaching Methods--Project-based Learning in Physics

    Science.gov (United States)

    Holubova, Renata

    2008-01-01

    The paper presents results of the research of new effective teaching methods in physics and science. It is found out that it is necessary to educate pre-service teachers in approaches stressing the importance of the own activity of students, in competences how to create an interdisciplinary project. Project-based physics teaching and learning…

  1. A novel electrochemical preparation of PbS nanoparticles

    International Nuclear Information System (INIS)

    Yang Yujun

    2006-01-01

    A simple one-step anodic sonoelectrochemical method to synthesize PbS nanoparticles has been developed. With the lead foil as the sacrificing anode, Pb(II) was anodically dissolved from the lead electrode into the aqueous solution of sodium sulfide, supporting electrolyte (potassium nitrate) and capping agent (PVA) at a constant potential, and then the produced Pb(II) reacted with the sulfide anion to form PbS nanoparticles under ultrasonic irradiation. The effects of the applied potential, capping agent and ultrasound in the formation of PbS nanoparticles are discussed, and the results suggest that the anodic sonoelectrochemical method may be a general and convenient way to prepare metal sulfide nanoparticles

  2. Project-Based Learning in Scottish Prisons

    Science.gov (United States)

    Sams, Kirsten

    2014-01-01

    The article describes the development of a project-based approach to learning in seven Scottish prisons. It argues that the project-based approach is ideally suited to prison education due to its flexibility and ability to enrich the relatively narrow prison curriculum and create meaningful links with wider society, reducing the isolation of…

  3. 77 FR 40358 - Federal Management Regulation; FMR Bulletin PBS-2012-03; Redesignations of Federal Buildings...

    Science.gov (United States)

    2012-07-09

    ... Management Regulation; FMR Bulletin PBS-2012-03; Redesignations of Federal Buildings: Correction AGENCY: Public Buildings Service (PBS), General Services Administration (GSA). ACTION: Notice of a bulletin..., 2012, a bulletin announcing the designation and redesignation of three Federal buildings. Inadvertently...

  4. Spanish adaptation of the Participatory Behaviors Scale (PBS

    Directory of Open Access Journals (Sweden)

    Alejandro Magallares

    2016-04-01

    Full Text Available The aim of this study was to adapt the Participatory Behaviors Scale (PBS and validate the results for use among the Spanish population. Using snowball sampling methodology, 501 individuals from all areas of Spain were selected to participate in the study. The Participatory Behaviors Scale (PBS and questionnaires that measure a sense of community, belief in a just world and Machiavellianism were used to analyze the criterion validity of the adapted scale. A confirmatory factor analysis indicated that the items on the questionnaire fit a second-order model with four factors, which corresponded to the four dimensions proposed by the original authors, namely, disengagement, civil participation, formal political participation and activism. Additionally, it has been found that the scale is related to a sense of community, belief in a just world and Machiavellianism. In light of these results, we concluded that the questionnaire is methodologically valid and can be used by the scientific community to measure participatory behavior.

  5. Optical properties of PbS thin films

    Energy Technology Data Exchange (ETDEWEB)

    Akhmedov, O. R., E-mail: orucahmedov@mail.ru; Guseinaliyev, M. G. [National Academy of Azerbaijan, Nakhichevan Branch (Azerbaijan); Abdullaev, N. A.; Abdullaev, N. M.; Babaev, S. S.; Kasumov, N. A. [National Academy of Sciences of Azerbaijan, Abdullaev Institute of Physics (Azerbaijan)

    2016-01-15

    The complex dielectric function of PbS thin films is studied by spectroscopic ellipsometry in the spectral range from 0.74 to 6.45 eV at a temperature of 293 K. The critical energies are determined to be E{sub 1} = 3.53 eV and E{sub 2} = 4.57 eV. For both energy regions, the best fit is attained at the critical point 2D (m = 0). In addition, the Raman spectra and the optical-absorption spectra of PbS thin films are studied. From the dependence of the quantity (αhν){sup 2} on the photon energy hν, the band gap is established at E{sub g} = 0.37 eV.

  6. Graphene and PbS quantum dot hybrid vertical phototransistor

    Science.gov (United States)

    Song, Xiaoxian; Zhang, Yating; Zhang, Haiting; Yu, Yu; Cao, Mingxuan; Che, Yongli; Dai, Haitao; Yang, Junbo; Ding, Xin; Yao, Jianquan

    2017-04-01

    A field-effect phototransistor based on a graphene and lead sulfide quantum dot (PbS QD) hybrid in which PbS QDs are embedded in a graphene matrix has been fabricated with a vertical architecture through a solution process. The n-type Si/SiO2 substrate (gate), Au/Ag nanowire transparent source electrode, active layer and Au drain electrode are vertically stacked in the device, which has a downscaled channel length of 250 nm. Photoinduced electrons in the PbS QDs leap into the conduction band and fill in the trap states, while the photoinduced holes left in the valence band transfer to the graphene and form the photocurrent under biases from which the photoconductive gain is evaluated. The graphene/QD-based vertical phototransistor shows a photoresponsivity of 2 × 103 A W-1, and specific detectivity up to 7 × 1012 Jones under 808 nm laser illumination with a light irradiance of 12 mW cm-2. The solution-processed vertical phototransistor provides a new facile method for optoelectronic device applications.

  7. Application of Technology in Project-Based Distance Learning

    Directory of Open Access Journals (Sweden)

    Ali Mehrabian

    2008-06-01

    Full Text Available Present technology and the accessibility of internet have made distance learning easier, more efficient, and more convenient for students. This technology allows instructors and students to communicate asynchronously, at times and locations of their own choosing, by exchanging printed or electronic information. The use of project-based approach is being recognized in the literature as a potential component of courses in the faculties of engineering, science, and technology. Instructors may have to restructure their course differently to accommodate and facilitate the effectiveness of distance learning. A project-based engineering course, traditionally taught in a classroom settings using live mode at the College of Engineering and Computer Sciences at the University of Central Florida (UCF has been transformed to a distance course taught using distance modes. In this case, pedagogical transitions and adjustments are required, in particular for obtaining an optimal balance between the course material and the project work. Project collaboration in groups requires communication, which is possible with extensive utilization of new information and communication technology, such as virtual meetings. This paper discusses the course transition from live to distance modes and touches on some issues as they relate to the effectiveness of this methodology and the lessons learned from its application within different context. More specifically, this discussion includes the benefit of implementing project-based work in the domain of the distance learning courses.

  8. Continued multidisciplinary project-based learning - implementation in health informatics.

    Science.gov (United States)

    Wessel, C; Spreckelsen, C

    2009-01-01

    Problem- and project-based learning are approved methods to train students, graduates and post-graduates in scientific and other professional skills. The students are trained on realistic scenarios in a broader context. For students specializing in health informatics we introduced continued multidisciplinary project-based learning (CM-PBL) at a department of medical informatics. The training approach addresses both students of medicine and students of computer science. The students are full members of an ongoing research project and develop a project-related application or module, or explore or evaluate a sub-project. Two teachers guide and review the students' work. The training on scientific work follows a workflow with defined milestones. The team acts as peer group. By participating in the research team's work the students are trained on professional skills. A research project on a web-based information system on hospitals built the scenario for the realistic context. The research team consisted of up to 14 active members at a time, who were scientists and students of computer science and medicine. The well communicated educational approach and team policy fostered the participation of the students. Formative assessment and evaluation showed a considerable improvement of the students' skills and a high participant satisfaction. Alternative education approaches such as project-based learning empower students to acquire scientific knowledge and professional skills, especially the ability of life-long learning, multidisciplinary team work and social responsibility.

  9. Organizational Diagnosis in Project-Based Companies

    Directory of Open Access Journals (Sweden)

    Behrouz Zarei

    2014-05-01

    Full Text Available The purpose of this article is to develop a new method for corporate diagnosis (CD. To this end, a method is developed for the diagnosis process of project-based companies. The article presents a case study in a large company where data have been collected through focus groups. Project delay, high project cost, and low profitability are examples of project deficiency in project-based companies. Such issues have made managers pay special attention to find effective solutions to improve them. Prominent factors are inappropriate strategy, structure, system, human resource management, and PMBOK(Project Management Body of Knowledge processes. Thus, CD and analysis is an important task in improvement of corporate performance. The CD model that is developed in this article could be used for project-based companies. The proposed method can be used for CD in any project-based company. This article provides an emphatic application of CD as a prerequisite for restructuring in project-based companies.

  10. Efficient 3M PBS enhancing miniature projection optics

    Science.gov (United States)

    Yun, Zhisheng; Nevitt, Timothy; Willett, Stephen; Mortenson, Dave; Le, John; McDowell, Erin; Kent, Susan; Wong, Timothy; Beniot, Gilles J.; Ouderkirk, Andrew

    2016-09-01

    Over the past decade, 3M has developed a number of mobile projectors, with a goal towards providing the world's smallest, most efficient projection systems. Compact size and efficiency are required characteristics for projection systems used in mobile devices and more lately, in augmented reality systems. In this paper we summarize the main generations of 3M light engine optical designs. We present the optical architectures of four light engines, including the rationale behind the illumination designs and the projection systems. In particular, we describe various configurations relating to the 3M polarizing beam splitter (PBS) which is key to enhanced efficiency of the miniature projection systems.

  11. Lights, Camera, Project-Based Learning!

    Science.gov (United States)

    Cox, Dannon G.; Meaney, Karen S.

    2018-01-01

    A physical education instructor incorporates a teaching method known as project-based learning (PBL) in his physical education curriculum. Utilizing video-production equipment to imitate the production of a televisions show, sixth-grade students attending a charter school invited college students to share their stories about physical activity and…

  12. A simple route for making surfactant free lead sulfide (PbS) quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Firoz; Kumar, Neetesh; Dutta, Viresh, E-mail: vdutta@ces.iitd.ac.in

    2015-05-15

    Highlights: • Surfactant free PbS NCs were successfully synthesised using CoSP technique. • The technique eliminates the requirements of washing to remove the ligands. • Grinding using mortar and pestle creates well separated PbS QDs. • Surfactant free PbS NCs are stable and do not show any degradation with time. - Abstract: An efficient, cost effective and less time consuming method suitable for mass production of surfactant free quantum dots (QDs) of lead sulfide (PbS) is reported. PbS nanocrystals (NCs) are first synthesised by continuous spray pyrolysis (CoSP) technique and de-agglomeration into PbS quantum dots (QDs) is achieved by vigorous mechanical grinding using mortar and pestle. Lead acetate and thiourea were used as the precursor materials for preparation of surfactant free PbS NCs. The broadening in XRD peaks of ground NCs as compared to as synthesized PbS NCs clearly indicated the reduction in particle size to be QDs of PbS. The TEM images also showed that ground PbS NCs were nearly spherical in shape having an average diameter in the range of 4–6 nm. The shift in optical gap from 0.41 eV to 1.47 eV supported the QD formation.

  13. Project- Based Learning and Problem-Based Learning: Are They Effective to Improve Student's Thinking Skills?

    OpenAIRE

    Anazifa, R. D; Djukri, D

    2017-01-01

    The study aims at finding (1) the effect of project-based learning and problem-based learning on student's creativity and critical thinking and (2) the difference effect of project-based learning and problem-based learning on student's creativity and critical thinking. This study is quasi experiment using non-equivalent control-group design. Research population of this study was all classes in eleventh grade of mathematics and natural science program of SMA N 1 Temanggung. The participants we...

  14. A Project-Based Course on Newton's Laws for Talented Junior High-School Students

    Science.gov (United States)

    Langbeheim, Elon

    2015-01-01

    Research has shown that project-based learning promotes student interest in science and improves understanding of scientific content. Fostering student motivation is particularly important in accelerated science and technology programmes for talented students, which are often demanding and time-consuming. Current texts provide little guidance on…

  15. A New Project-Based Lab for Undergraduate Environmental and Analytical Chemistry

    Science.gov (United States)

    Adami, Gianpiero

    2006-01-01

    A new project-based lab was developed for third year undergraduate chemistry students based on real world applications. The experience suggests that the total analytical procedure (TAP) project offers a stimulating alternative for delivering science skills and developing a greater interest for analytical chemistry and environmental sciences and…

  16. Knowledge Governance in Project-Based Organizations

    DEFF Research Database (Denmark)

    Pemsel, Sofia; Wiewiora, Anna; Müller, Ralf

    This paper conceptualizes knowledge governance (KG) in project-based organizations (PBOs) and its methodological approaches for empirical investigation. Three key contributions towards a multi-faceted view of KG and an understanding of KG in PBOs are advanced. These contributions include a defini......This paper conceptualizes knowledge governance (KG) in project-based organizations (PBOs) and its methodological approaches for empirical investigation. Three key contributions towards a multi-faceted view of KG and an understanding of KG in PBOs are advanced. These contributions include...... a definition of KG in PBOs, a conceptual framework to investigate KG and a methodological framework for empirical inquiry into KG in PBO settings. Our definition highlights the contingent nature of KG processes in relation to their organizational context. The conceptual framework addresses macro- and micro...

  17. Visualizing Practices in Project-based Design

    DEFF Research Database (Denmark)

    Whyte, Jennifer; Tryggestad, Kjell; Comi, Alice

    2016-01-01

    Project-based design involves a variety of visual representations, which are evolved to make decisions and accomplish project objectives. Yet, such mediated and distributed ways of working are difficult to capture through ethnographies that examine situated design. A novel approach is developed t...... representations enabled participants in project-based design to develop and share understanding. The complexity of projects and their distributed and mediated nature makes this approach timely and important in addressing new research questions and practical challenges.......Project-based design involves a variety of visual representations, which are evolved to make decisions and accomplish project objectives. Yet, such mediated and distributed ways of working are difficult to capture through ethnographies that examine situated design. A novel approach is developed...... of situated design. This allows the researcher to be nimble, tracing connections across complex engineering projects; reconstructing practices through their visual representations; and observing their effects. Second, it articulates how, in these empirical cases, interaction with a cascade of visual...

  18. Performance-based standards (PBS) vehicles for transport in the agricultural sector

    CSIR Research Space (South Africa)

    Nordengen, Paul A

    2008-07-01

    Full Text Available manufacturers start designing vehicles on an ad hoc basis. It should be borne in mind that PBS vehicle designs include certain safety features, and must be loaded in the correct manner. The RTMS approach offers the most suitable way of ensuring.... The objectives of the Performance-Based Standards (PBS) philosophy are to utilise technology to reduce road damage, improve safety, increase payloads and reduce costs. To overcome the limitations of prescriptive legislation, is has been proposed that PBS...

  19. Nongeminate radiative recombination of free charges in cation-exchanged PbS quantum dot films

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Ashley R. [National Renewable Energy Laboratory, 15013 Denver West Pkwy., Golden, CO 80401 (United States); Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309 (United States); Beard, Matthew C.; Johnson, Justin C. [National Renewable Energy Laboratory, 15013 Denver West Pkwy., Golden, CO 80401 (United States)

    2016-06-01

    Highlights: • Photoluminescence and transient absorption are used to probe PbS QD films. • Cation-exchanged PbS QDs show room-temperature PL emission. • Bimolecular recombination is shown for the first time in coupled, PbS QD films. - Abstract: Using photoluminescence (PL) spectroscopy we explore the radiative recombination pathways in PbS quantum dots (QDs) synthesized by two methods. We compare conventionally synthesized PbS from a PbO precursor to PbS synthesized using cation-exchange from CdS QDs. We show that strongly coupled films of PbS QDs from the cation-exchange luminesce with significant efficiency at room temperature. This is in stark contrast to conventional PbS QDs, which have exceedingly weak room temperature emission. Moreover, the power dependence of the emission is quadratic, indicating bimolecular radiative recombination that is reasonably competitive with trap-assisted recombination, a feature previously unreported in coupled PbS QD films. We interpret these results in terms of a greatly reduced defect concentration for cation-exchanged QDs that mitigates the influence of trap-assisted recombination. Cation-exchanged QDs have recently been employed in highly efficient and air-stable lead chalcogenide QD devices, and the reduced number of trap states inferred here may lead to improved current collection and higher open circuit voltage.

  20. Charge transfer between acenes and PbS nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Dissanayake, D M N M [Solid State Electronics Laboratory, University of Michigan, Ann Arbor, MI 48109-2122 (United States); Hatton, R A [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom); Lutz, T [Departments of Chemistry and Physics, Imperial College, London SW7 2AY (United Kingdom); Curry, R J; Silva, S R P [Advanced Technology Institute, University of Surrey, Guildford GU2 7XH (United Kingdom)], E-mail: ndissa@umich.edu

    2009-05-13

    Organic-inorganic hybrid heterojunctions have potential as the basis for future photovoltaic devices. Herein, we report the results of investigations exploring the possibility of using pentacene and tetracene as photoelectron donors in conjunction with PbS nanocrystals (PbS-NCs). Photoinduced charge transfer was probed using external quantum efficiency measurements on acene:PbS-NC hybrid photovoltaic devices in conjunction with photoluminescence studies of the corresponding bilayer films. It is shown that photoelectron transfer from pentacene to the PbS-NCs is inefficient as compared to that between tetracene and PbS-NCs. The latter case can be rationalized in terms of the energy level alignment at the heterojunction assuming a common vacuum level. However, in the case of pentacene:PbS-NC junctions an interfacial energy level shift must be considered in order to explain the observations.

  1. A Reversible Photoacid Functioning in PBS Buffer under Visible Light.

    Science.gov (United States)

    Abeyrathna, Nawodi; Liao, Yi

    2015-09-09

    A metastable-state photoacid that can reversibly release a proton in PBS buffer (pH = 7.4) under visible light is reported. The design is based on the dual acid-base property and tautomerization of indazole. The quantum yield was as high as 0.73, and moderate light intensity (10(2) μmol·m(2)·s(-1)) is sufficient for the photoreaction. Reversible pH change of 1.7 units was demonstrated using a 0.1 mM aqueous solution. This type of photoacid is promising for control of proton-transfer processes in physiological conditions and may find applications in biomedical areas.

  2. 基于区间贝叶斯模型的科技项目风险决策%Risk Decision Making of Science and Technology Project Based on Interval Bayesian Model

    Institute of Scientific and Technical Information of China (English)

    董正国; 王凭慧

    2012-01-01

    Because the science and technology project involves an innovative process with high difficulty and high risk,its risk decision making and risk controlling is regarded as the most important part among the whole project management.As it is difficult to obtain the integrated and accurate information in risk decision making and risk controlling process and most of the data are interval,the conventional Bayesian model cannot deal with this issue.In this paper,the theory of interval data is introduced into the traditional Bayesian model,combining with the theory of possibility,and then the traditional Bayesian model is generalized to the interval data condition.Therefore,this method can be used to deal with the risk decision problem of the technology projects.The analysis of one example shows that this interval Bayesian model commendably can solve the risk decision making of technology project.The content of this study provides a certain reference for the further research in this area.%科技项目是一个高难度和高风险的创新过程,其风险决策与控制是整个项目管理的一项重要内容。鉴于该过程中往往缺乏准确的信息,出现较多的区间数据,利用传统的贝叶斯模型很难对其进行处理。本文运用区间数理论将传统的贝叶斯风险决策模型推广应用到了区间不确定型问题,并结合可能度理论很好地解决了科技项目的风险决策问题。通过具体的实例分析,取得了很好地效果,证实了该理论模型应用于科技项目风险决策的可行性,给相关领域的研究工作提供了参考。

  3. The Effectiveness of Project-based E-learning to Improve Ict Literacy

    OpenAIRE

    Eliana, E. D. S; Senam, Senam; Wilujeng, I; Jumadi, Jumadi

    2016-01-01

    This study aims to reveal the effectiveness of science teaching based on project-based learning to improve ICT literacy learners in the junior high school with the category of high, medium and low. This research uses descriptive method to describe the students’ equipness of ICT literacy in the science learning based on the project-based learning that is integrated with e-learning. All of the population in this study are junior high school of curriculum pilot project in 2013 in Singkawang. The...

  4. Monitoring results of two PBS demonstration vehicles in the forestry industry in South Africa

    CSIR Research Space (South Africa)

    Nordengen, Paul A

    2010-03-01

    Full Text Available and manufactured to comply with the Level 2 safety standards of the Australian PBS system. This paper presents a summary of the monitoring data compiled during the first nine months of operation of the two PBS demonstration vehicles, which were commissioned...

  5. Study of the back recombination processes of PbS quantum dots sensitized solar cells

    Science.gov (United States)

    Badawi, Ali; Al-Hosiny, N.; Merazga, Amar; Albaradi, Ateyyah M.; Abdallah, S.; Talaat, H.

    2016-12-01

    In this study, the back recombination processes of PbS quantum dots sensitized solar cells (QDSSCs) has been investigated. PbS QDs were adsorbed onto titania electrodes to act the role of sensitizers using successive ionic layer adsorption and reaction (SILAR) technique. The energy band gaps of the synthesized PbS QDs/titania are ranged from 1.64 eV (corresponding to 756 nm) to 3.12 eV (397 nm) matching the whole visible solar spectrum. The hyperbolic band model (HBM) was used to calculate PbS QDs size and it ranges from 1.76 to 3.44 nm. The photovoltaic parameters (open circuit voltage Voc, short circuit current density Jsc, fill factor FF and efficiency η) of the assembled PbS QDs sensitized solar cells (QDSSCs) were determined under a solar illumination of 100 mW/cm2 (AM 1.5 conditions). The open circuit voltage-decay (OCVD) rates of the assembled PbS QDSSCs were measured. The time constant (τ) for PbS QDSSCs (4 SILAR cycles) shows one order of magnitude larger than that of PbS QDSSCs (8 SILAR cycles) as a result of a decreased electron-hole back recombination.

  6. Synthesis and Characterization of Quantum Dots: A Case Study Using PbS

    Science.gov (United States)

    Pan, Yi; Li, Yue Ru; Zhao, Yu; Akins, Daniel L.

    2015-01-01

    A research project for senior undergraduates of chemistry has been developed to introduce syntheses of a series of monodispersed semiconductor PbS quantum dots (QDs) and their characterization methodologies. In this paper, we report the preparation of monodispersed semiconductor PbS QDs with sizes smaller than the exciton Bohr radius using a…

  7. A methodology for assessment of road structures for the PBS pilot project in South Africa

    CSIR Research Space (South Africa)

    Nordengen, Paul A

    2016-11-01

    Full Text Available This paper describes the methodology that is being used for the performance assessment of PBS vehicles in terms of road structures as part of the PBS pilot project in South Africa. The assessment approach has evolved from the standard “bridge...

  8. Designing heavy vehicles to be safer and more productive using PBS

    CSIR Research Space (South Africa)

    Kienhöfer, FW

    2013-07-01

    Full Text Available condition that the proposed vehicle’s safety is demonstrated either through physical testing or simulations. Such a PBS approach is currently being evaluated in South Africa. This paper summarises the productivity and safety increases of three PBS...

  9. Self-assembled colloidal PbS quantum dots on GaAs substrates

    International Nuclear Information System (INIS)

    Lue, Wei; Yamada, Fumihiko; Kamiya, Itaru

    2010-01-01

    We report the fabrication and analysis of self-assembled monolayer and bilayer films of colloidal PbS quantum dots (QDs) on GaAs (001) substrates. 1,6-hexanedithiol is used as link molecule between QDs and GaAs substrates. Atomic force microscopy (AFM) and photoluminescence (PL) measurements confirm the formation of PbS QD film on GaAs. For the monolayer PbS QD film, the temperature-dependent PL shows a feature typical of close-packed film. For the bilayer PbS QD film fabricated from two different mean-sized PbS QDs, we find that the stacking sequence of QDs with different size affects the quantum yield and emission wavelength of the film.

  10. Origins of Stokes shift in PbS nanocrystals

    KAUST Repository

    Voznyy, Oleksandr

    2017-10-27

    Stokes shift, an energy difference between the excitonic absorption and emission, is a property of colloidal quantum dots (CQDs) typically ascribed to splitting between dark and bright excitons. In some materials, e.g., PbS, CuInS2, CdHgTe, a Stokes shift of up to 200 meV is observed, substantially larger than the estimates of dark-bright state splitting or vibronic relaxations. The shift origin remains highly debated, as contradictory signatures of both surface and bulk character were reported for the Stokes-shifted electronic state. Here we show that the energy transfer among CQDs in a polydispersed ensemble in solution suffices to explain the excess Stokes shift. This energy transfer is primarily due to CQD aggregation, and can be substantially eliminated by extreme dilution, higher-viscosity solvent, or better-dispersed colloids. Our findings highlight that ensemble polydispersity remains the primary source of the Stokes shift in CQDs in solution, propagating into the Stokes shift in films and the open-circuit voltage deficit in CQD solar cells. Improved synthetic control can bring notable advancements in CQD photovoltaics, and the Stokes shift continues to provide a sensitive and significant metric to monitor ensemble size distribution.

  11. Mechanical Properties in a Bamboo Fiber/PBS Biodegradable Composite

    Science.gov (United States)

    Ogihara, Shinji; Okada, Akihisa; Kobayashi, Satoshi

    In recent years, biodegradable plastics which have low effect on environment have been developed. However, many of them have lower mechanical properties than conventional engineering plastics. Reinforcing them with a natural fiber is one of reinforcing methods without a loss of their biodegradability. In the present study, we use a bamboo fiber as the reinforcement and polybutylenesuccinate (PBS) as the matrix. We fabricate long fiber unidirectional composites and cross-ply laminate with different fiber weight fractions (10, 20, 30, 40 and 50wt%). We conduct tensile tests to evaluate the mechanical properties of these composites. In addition, we measure bamboo fiber strength distribution. We discuss the experimentally-obtained properties based on the mechanical properties of the constituent materials. Young's modulus and tensile strength in unidirectional composite and cross-ply laminate increase with increasing fiber weight fraction. However, the strain at fracture showed decreasing tendency. Young's modulus in fiber and fiber transverse directions are predictable by the rules of mixture. Tensile strength in fiber direction is lower than Curtin's prediction of strength which considers distribution of fiber strength. Young's modulus in cross-ply laminate is predictable by the laminate theory. However, analytical prediction of Poisson's ratio in cross-ply laminate by the laminate theory is lower than the experimental results.

  12. Solvent Engineering for High-Performance PbS Quantum Dots Solar Cells

    Directory of Open Access Journals (Sweden)

    Rongfang Wu

    2017-07-01

    Full Text Available PbS colloidal quantum dots (CQDs solar cells have already demonstrated very impressive advances in recent years due to the development of many different techniques to tailor the interface morphology and compactness in PbS CQDs thin film. Here, n-hexane, n-octane, n-heptane, isooctane and toluene or their hybrids are for the first time introduced as solvent for comparison of the dispersion of PbS CQDs. PbS CQDs solar cells with the configuration of PbS/TiO2 heterojunction are then fabricated by using different CQDs solution under ambient conditions. The performances of the PbS CQDs solar cells are found to be tuned by changing solvent and its content in the PbS CQDs solution. The best device could show a power conversion efficiency (PCE of 7.64% under AM 1.5 G illumination at 100 mW cm−2 in a n-octane/isooctane (95%/5% v/v hybrid solvent scheme, which shows a ~15% improvement compared to the control devices. These results offer important insight into the solvent engineering of high-performance PbS CQDs solar cells.

  13. Enhancing Project-Based Learning in Software Engineering Lab Teaching through an E-Portfolio Approach

    Science.gov (United States)

    Macias, J. A.

    2012-01-01

    Project-based learning is one of the main successful student-centered pedagogies broadly used in computing science courses. However, this approach can be insufficient when dealing with practical subjects that implicitly require many deliverables and a great deal of feedback and organizational resources. In this paper, a worked e-portfolio is…

  14. A Project-Based Engineering and Leadership Workshop for High School Students

    Science.gov (United States)

    Ryder, Linda Sue; Pegg, Jerine; Wood, Nathan

    2012-01-01

    Summer outreach programs provide pre-college participants an introduction to college life and exposure to engineering in an effort to raise the level of interest and bring more students into engineering fields. The Junior Engineering, Mathematics, and Science (JEMS) program is a project-based summer workshop in which teams of high school students…

  15. The Impact of Project-Based Learning on Pre-Service Teachers' Technology Attitudes and Skills

    Science.gov (United States)

    Alexander, Curby; Knezek, Gerald; Christensen, Rhonda; Tyler-Wood, Tandra; Bull, Glen

    2014-01-01

    Researchers in this study looked at the effect of content-specific, technology-rich project-based learning activities on EC-8 pre-service teachers' competencies and skills, as well as pre-service teacher's attitudes toward science, technology, engineering and mathematics (STEM). Researchers employed a quantitative design involving participants in…

  16. Math Path: Encouraging Female Students in Mathematics through Project-Based Learning

    Science.gov (United States)

    Evans, Riley; Friedman, Jane; McGrath, Lynn; Myers, Perla; Ruiz, Amanda

    2018-01-01

    Although the number of bachelor's degrees in the U.S. awarded to women has gone up, engagement of women in science, technology, engineering, and mathematics (STEM) continues to be low. This paper presents a project-based learning program, informed by education research best practices, designed to provide research experiences to female students…

  17. Multi-Role Project (MRP): A New Project-Based Learning Method for STEM

    Science.gov (United States)

    Warin, Bruno; Talbi, Omar; Kolski, Christophe; Hoogstoel, Frédéric

    2016-01-01

    This paper presents the "Multi-Role Project" method (MRP), a broadly applicable project-based learning method, and describes its implementation and evaluation in the context of a Science, Technology, Engineering, and Mathematics (STEM) course. The MRP method is designed around a meta-principle that considers the project learning activity…

  18. Implementation of Project Based Learning in Mechatronic Lab Course at Bandung State Polytechnic

    Science.gov (United States)

    Basjaruddin, Noor Cholis; Rakhman, Edi

    2016-01-01

    Mechatronics is a multidisciplinary that includes a combination of mechanics, electronics, control systems, and computer science. The main objective of mechatronics learning is to establish a comprehensive mindset in the development of mechatronic systems. Project Based Learning (PBL) is an appropriate method for use in the learning process of…

  19. Spectroscopic evidence of resonance energy transfer mechanism from PbS QDs to bulk silicon

    Directory of Open Access Journals (Sweden)

    Bernechea M.

    2013-06-01

    Full Text Available In this work, we study the efficiency of the resonance energy transfer from PbS quantum dots to bulk silicon. We present spectroscopic evidence that resonance energy transfer from PbS quantum dots to bulk silicon can be an efficient process for separation distances below 12 nm. Temperature measurements are also presented for PbS quantum dots deposited on glass and silicon with 5 nm and 20nm spacer thicknesses substrates. Our findings show that the resonance energy transfer efficiency remains constant over the 50K to 300K temperature range.

  20. Project based learning for reactor engineering education

    International Nuclear Information System (INIS)

    Narabayashi, Tadashi; Tsuji, Masashi; Shimazu, Yoichiro

    2009-01-01

    Trial in education of nuclear engineering in Hokkaido University has proved to be quite attractive for students. It is an education system called Project Based Learning (PBL), which is not based on education by lecture only but based mostly on practice of students in the classroom. The system was adopted four years ago. In the actual class, we separated the student into several groups of the size about 6 students. In the beginning of each class room time, a brief explanations of the related theory or technical bases. Then the students discuss in their own group how to precede their design calculations and do the required calculation and evaluation. The target reactor type of each group was selected by the group members for themselves at the beginning of the semester as the first step of the project. The reactor types range from a small in house type to that for a nuclear ship. At the end of the semester, each group presents the final design. The presentation experience gives students a kind of fresh sensation. Nowadays the evaluation results of the subject by the students rank in the highest in the faculty of engineering. Based on the considerations above, we designed the framework of our PBL for reactor engineering. In this paper, we will present some lessons learned in this PBL education system from the educational points of view. The PBL education program is supported by IAE/METI in Japan for Nuclear Engineering Education. (author)

  1. Oleic acid capped PbS nanoparticles: Synthesis, characterization and tribological properties

    International Nuclear Information System (INIS)

    Chen Shuang; Liu Weimin

    2006-01-01

    Oleic acid (OA) capped PbS nanoparticles were chemically synthesized and characterized by means of Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray electron diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The triboligical properties of the capped PbS nanoparticles as additive in liquid paraffin was investigated using a four-ball machine. The lubricating mechanisms were discussed along with the analyses results of XPS and scanning electron microscope (SEM). Results show that OA-capped PbS nanoparticles, with an average diameter of about 8 nm, are able to prevent water adsorption, oxidation and are capable of being dispersed stably in organic solvents or mineral oil. OA-capped PbS nanoparticles as an additive in liquid paraffin perform good antiwear and friction-reduction properties owing to the formation of a boundary film

  2. Inorganic-ligand exchanging time effect in PbS quantum dot solar cell

    International Nuclear Information System (INIS)

    Kim, Byung-Sung; Hong, John; Hou, Bo; Cho, Yuljae; Sohn, Jung Inn; Cha, SeungNam; Kim, Jong Min

    2016-01-01

    We investigate time-dependent inorganic ligand exchanging effect and photovoltaic performance of lead sulfide (PbS) nanocrystal films. With optimal processing time, volume shrinkage induced by residual oleic acid of the PbS colloidal quantum dot (CQD) was minimized and a crack-free film was obtained with improved flatness. Furthermore, sufficient surface passivation significantly increased the packing density by replacing from long oleic acid to a short iodide molecule. It thus facilities exciton dissociation via enhanced charge carrier transport in PbS CQD films, resulting in the improved power conversion efficiency from 3.39% to 6.62%. We also found that excess iodine ions on the PbS surface rather hinder high photovoltaic performance of the CQD solar cell.

  3. Search for Spin Filtering By Electron Tunneling Through Ferromagnetic EuS Barriers in Pbs

    Science.gov (United States)

    Figielski, T.; Morawski, A.; Wosinski, T.; Wrotek, S.; Makosa, A.; Lusakowska, E.; Story, T.; Sipatov, A. Yu.; Szczerbakow, A.; Grasza, K.; hide

    2002-01-01

    Perpendicular transport through single- and double-barrier heterostructures consisting of ferromagnetic EuS layers embedded into PbS matrix was investigated. Manifestations of both resonant tunneling and spin filtering through EuS barrier have been observed.

  4. Inorganic-ligand exchanging time effect in PbS quantum dot solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byung-Sung; Hong, John; Hou, Bo; Cho, Yuljae; Sohn, Jung Inn, E-mail: junginn.sohn@eng.ox.ac.uk, E-mail: seungnam.cha@eng.ox.ac.uk; Cha, SeungNam, E-mail: junginn.sohn@eng.ox.ac.uk, E-mail: seungnam.cha@eng.ox.ac.uk [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ (United Kingdom); Kim, Jong Min [Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom)

    2016-08-08

    We investigate time-dependent inorganic ligand exchanging effect and photovoltaic performance of lead sulfide (PbS) nanocrystal films. With optimal processing time, volume shrinkage induced by residual oleic acid of the PbS colloidal quantum dot (CQD) was minimized and a crack-free film was obtained with improved flatness. Furthermore, sufficient surface passivation significantly increased the packing density by replacing from long oleic acid to a short iodide molecule. It thus facilities exciton dissociation via enhanced charge carrier transport in PbS CQD films, resulting in the improved power conversion efficiency from 3.39% to 6.62%. We also found that excess iodine ions on the PbS surface rather hinder high photovoltaic performance of the CQD solar cell.

  5. Molecular characterization of Fagaceae species using inter-primer binding site (iPBS) markers.

    Science.gov (United States)

    Coutinho, João Paulo; Carvalho, Ana; Martín, Antonio; Lima-Brito, José

    2018-04-01

    Retrotransposons (RTNs) contribute for genome evolution, influencing its size and structure. We investigated the utility of the RTN-based markers inter-primer binding site (iPBS) for the molecular characterization of 25 Fagaceae species from genera Castanea, Fagus and Quercus. The assessment of genetic diversity, relationships and structure, as well as taxonomic classification of Fagaceae based on molecular data is important for definition of conservation, forestry management strategies and discrimination among natural hybrids and their parents since natural hybridization may increase with the climate changes. Here, iPBS primers designed by other authors were tested alone and combined. Some of them were discriminative, revealed polymorphism within and among taxa allowing the production of a total of 150 iPBS markers. In addition, several monomorphic iPBS markers were also amplified in each taxon. The UPGMA dendrogram based on the pooled iPBS data revealed 27% of genetic similarity among species. The individuals were clustered per genus and most of the oaks per infrageneric group corroborating the adopted taxonomy. Globally, the iPBS markers demonstrated suitability for DNA fingerprinting, determination of phylogenies and taxonomic discrimination in Fagaceae, and could constitute a useful and alternative tool for germplasm characterization, and for definition of conservation strategies and forestry management. Moreover, these markers would be useful for fingerprinting natural hybrids that share morphological similarities with their parents. Since iPBS markers could also enable insights about RTNs evolution, an eventual correlation among iPBS polymorphism, variability of RTN insertions and/or genome size in Fagaceae is discussed.

  6. Modeling the PbS quantum dots complex dielectric function by adjusting the E-k diagram critical points of bulk PbS

    Science.gov (United States)

    Hechster, Elad; Sarusi, Gabby

    2017-07-01

    The complex dielectric function ɛ(E )=ɛR(E )+i ɛI(E ) of a semiconductor is a key parameter that dictates the material's optical and electrical properties. Surprisingly, the ɛ(E ) of Lead Sulfide (PbS) quantum dots (QDs) has not been widely studied. In the present work, we develop a new model that aims to simulate the ɛ(E ) of QDs. Our model is based on the fact that the quantum confinement in the nano regime affects all the electronic transitions throughout the entire Brillouin zone. Hence, as a first approximation, we attribute an equal contribution of energy, equivalent to the bandgap broadening, to each critical point (CP) in the E-k diagram. This is mathematically realized by adding these energy contributions to the central energy parameters of the Lorentz oscillator model. In order to validate our model, we used the CP parameters of bulk PbS to simulate the ɛ(E ) of PbS QDs. Next, we use Maxwell Relations to calculate the refractive index and the extinction coefficient of PbS QDs from ɛ(" separators="|E ). Our results were compared with those published in the previous literature and showed good agreement. Our findings open a new avenue that may enable the calculation of the ɛ(" separators="|E ) for nanoparticle systems.

  7. Digital Media for STEM Learning: Developing scientific practice skills in the K-12 STEM classroom with resources from WGBH and PBS LearningMedia

    Science.gov (United States)

    Foster, J.; Connolly, R.

    2017-12-01

    WGBH's "Bringing the Universe to America's Classrooms" project is a 5-year effort to design, produce and evaluate digital media tools and resources that support scientific practice skills in diverse K-12 learners. Resources leverage data and content from NASA and WGBH signature programs, like NOVA, into sound instructional experiences that provide K-12 STEM teachers with free, quality resources for teaching topics in the Earth and Space Sciences. Resources address the content and practices in the new K-12 Framework for Science Education and are aligned with the NGSS. Participants will learn about design strategies, findings from our evaluation efforts, and how to access free resources on PBS LearningMedia.

  8. Conceptualizing the role of multidisciplinarity and student perceptions of university-industry collaboration in project-based learning

    OpenAIRE

    Heikkinen, Juho

    2017-01-01

    Project-based learning has a long history, especially in the disciplines of computer science and engineering. This approach is used to offer students a realistic view of their discipline, and this experience can be enhanced with industrial involvement as companies bring their real world problems to projects. One recent trend in project-based learning is utilizing multidisciplinary teams, enabling students to contrast their skills and experience with students from other discipli...

  9. ANALISIS PENGUASAAN KONSEP DAN KETERAMPILAN BERPIKIR KREATIF SISWA SD MELALUI PROJECT BASED LEARNING

    Directory of Open Access Journals (Sweden)

    Wa Ode Lidya Arisanti

    2017-02-01

    Full Text Available Abstract: Learning science is not just memorize the concepts, but learn how to process and mastery of the scientific attitude. Actually, learning is still centered on the teacher, so that students can develop the knowledge and skills of thinking. Knowledge and thinking skills students can experience a change in the proper way, one way that can be done by applying the model of project-based learning. This study aims to determine whether there is a difference mastery of concepts and creative thinking skills between classes that implement learning model project based learning and classroom rather than project-based learning on water recycling materials. The research design used in this study was Quasi Experimental Design devoted no pattern Nonequivalent Control Group Design This design consists of two groups: the experimental group and the control group. Furthermore, each class were given a pretest and posttest study with mastery test questions using the concept of multiple choice questions of 15 questions and test creative thinking skills with five essay questions on each test. Classroom learning experiment treated with a model project based learning and classroom learning with no control got projet models based learning. The results showed in general there are significant differences in mastery of concepts (p = 0.00 between the experimental class learning by applying the model of project-based learning in the learning process (the average N-gain = 0.477 in the medium category, with students learning by applying rather than project-based learning (the average N-gain = 0.290 in the low category. There is no difference in the ability to think creatively (p = 0.22 between the experimental class and control class, with an average N-gain the experimental class 0,075 while the control class is 0.060 which both are in the low category. Keywords: project based learning, mastery of concepts, creative   Abstrak: Belajar IPA bukan hanya menghafal konsep

  10. Teacher and Student Intrinsic Motivation in Project-Based Learning

    Science.gov (United States)

    Lam, Shui-fong; Cheng, Rebecca Wing-yi; Ma, William Y. K.

    2009-01-01

    In this study we examined the relationship between teacher and student intrinsic motivation in project-based learning. The participants were 126 Hong Kong secondary school teachers and their 631 students who completed evaluation questionnaires after a semester-long project-based learning program. Both teachers and students were asked to indicate…

  11. Organisational Memories in Project-Based Companies: An Autopoietic View

    Science.gov (United States)

    Koskinen, Kaj U.

    2010-01-01

    Purpose: The purpose of this paper is to describe project-based companies' knowledge production and memory development with the help of autopoietic epistemology. Design/methodology/approach: The discussion first defines the concept of a project-based company. Then the discussion deals with the two epistemological assumptions, namely cognitivist…

  12. 24 CFR 990.275 - Project-based management (PBM).

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Project-based management (PBM). 990... URBAN DEVELOPMENT THE PUBLIC HOUSING OPERATING FUND PROGRAM Asset Management § 990.275 Project-based... of rental housing at the project level. Under PBM, these property management services are arranged...

  13. Systemwide Implementation of Project-Based Learning: The Philadelphia Approach

    Science.gov (United States)

    Schwalm, Jason; Tylek, Karen Smuck

    2012-01-01

    Citywide implementation of project-based learning highlights the benefits--and the challenges--of promoting exemplary practices across an entire out-of-school time (OST) network. In summer 2009, the City of Philadelphia and its intermediary, the Public Health Management Corporation (PHMC), introduced project-based learning to a network of more…

  14. Project-Based Learning Not Just for STEM Anymore

    Science.gov (United States)

    Duke, Nell K.; Halvorsen, Anne-Lise; Strachan, Stephanie L.

    2016-01-01

    The popularity of project-based learning has been driven in part by a growing number of STEM schools and programs. But STEM subjects are not the only fertile ground for project-based learning (PBL). Social studies and literacy content, too, can be adapted into PBL units to benefit teaching and learning, the authors argue. They review key studies…

  15. Chemical bath deposited PbS thin films on ZnO nanowires for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Gertman, Ronen [Dept of Chemistry, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Osherov, Anna; Golan, Yuval [Dept of Materials Engineering, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Visoly-Fisher, Iris, E-mail: irisvf@bgu.ac.il [Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Sede Boqer Campus 84990 (Israel)

    2014-01-01

    Photovoltaic devices usually exploit mid-range band-gap semiconductors which absorb in the visible range of the solar spectrum. However, much energy is lost in the IR and near-IR range. We combined the advantages of small band-gap, bulk-like PbS deposited by facile, cheap and direct chemical bath deposition (CBD), with the good electronic properties of ZnO and the large surface area of nanowires, towards low cost photovoltaic devices utilizing IR and near-IR light. Surprisingly, CBD of PbS on ZnO, and particularly on ZnO nanowires, was not studied hitherto. Therefore, the mechanism of PbS growth by chemical bath deposition on ZnO nanowires was studied in details. A visible proof is shown for a growth mechanism starting from amorphous Pb(OH){sub 2} layer, that evolved into the ‘ion-by-ion’ growth mechanism. The growth mechanism and the resulting morphology at low temperatures were controlled by the thiourea concentration. The grain size affected the magnitude of the band-gap and was controlled by the deposition temperatures. Deposition above 40 °C resulted in bulk-like PbS with an optical band-gap of 0.4 eV. Methods were demonstrated for achieving complete PbS coverage of the complex ZnO NW architecture, a crucial requirement in optoelectronic devices to prevent shorts. Measurements of photocurrents under white and near-IR (784 nm) illumination showed that despite a 200 meV barrier for electron transfer at the PbS/ZnO interface, extraction of photo-electrons from PbS to the ZnO was feasible. The ability to harvest electrons from a narrow band-gap semiconductor deposited on a large surface-area electrode can advance the field towards high efficiency, low cost IR and near-IR sensors and third generation solar cells. - Highlights: • PbS was deposited on ZnO nanowires using chemical bath deposition. • At 50 °C the growth mechanism starts from an amorphous Pb(OH){sub 2} layer. • At 5 °C the growth mechanism of PbS can be controlled by thiourea concentrations

  16. Evaluation of genetic diversity in open pollinated guava by iPBS primers

    International Nuclear Information System (INIS)

    Mehmood, A.; Jaskani, M.J.; Ahmad, S.; Ahmad, R.

    2013-01-01

    DNA markers are important tools for assessing genetic diversity and relationships among species, cultivars and breeding materials. Many horticultural species are lacking genomic information. DNA markers that do not require prior knowledge of DNA sequences are therefore appealing for horticultural research. A retrotransposon-based DNA marker system, iPBS (inter primer binding sites) developed from conserved primer binding sites within retrotransposons, was used to study the genetic variation and relationships in ornamental guava. PCR from 6 iPBS primers (dominant markers) produced a total of 113 bands (52.38-100% polymorphic) ranging from 150 bp to 3000 bp, and the mean PIC value for each primer ranging from 0.1245 to 0.3698. Molecular information generated from both iPBS was separately scored in a matrix for phylogenetic dendrogram construction. The phylogenetic dendrogram based on iPBS markers reflected morphologic classifications of the accessions that were studied. The iPBS PCR-based genome fingerprinting technology in this study is low-cost and provides another effective alternative in differentiation of accessions in guava (Psidium guajava Linn.) and related species or genera. (author)

  17. Enhancement of the photovoltaic performance in P3HT: PbS hybrid solar cells using small size PbS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Firdaus, Yuliar; Van der Auweraer, Mark, E-mail: mark.vanderauweraer@chem.kuleuven.be [Laboratory of Photochemistry and Spectroscopy, Division of Molecular Imaging and Photonics, Chemistry Department, KULeuven, Celestijnenlaan 200F, 2404, B-3001 Leuven (Belgium); Vandenplas, Erwin; Gehlhaar, Robert; Cheyns, David [Imec vzw, Kapeldreef 75, B-3001 Leuven (Belgium); Justo, Yolanda; Hens, Zeger [Physical Chemistry Laboratory, Ghent University, Krijgslaan 281-S3, 9000 Gent (Belgium)

    2014-09-07

    Different approaches of surface modification of the quantum dots (QDs), namely, solution-phase (octylamine, octanethiol) and post-deposition (acetic acid, 1,4-benzenedithiol) ligand exchange were used in the fabrication of hybrid bulk heterojunction solar cell containing poly (3-hexylthiophene) (P3HT) and small (2.4 nm) PbS QDs. We show that replacing oleic acid by shorter chain ligands improves the figures of merit of the solar cells. This can possibly be attributed to a combination of a reduced thickness of the barrier for electron transfer and an optimized phase separation. The best results were obtained for post-deposition ligand exchange by 1,4-benzenedithiol, which improves the power conversion efficiency of solar cells based on a bulk heterojunction of lead sulfide (PbS) QDs and P3HT up to two orders of magnitude over previously reported hybrid cells based on a bulk heterojunction of P3HT:PbS QDs, where the QDs are capped by acetic acid ligands. The optimal performance was obtained for solar cells with 69 wt. % PbS QDs. Besides the ligand effects, the improvement was attributed to the formation of an energetically favorable bulk heterojunction with P3HT, when small size (2.4 nm) PbS QDs were used. Dark current density-voltage (J-V) measurements carried out on the device provided insight into the working mechanism: the comparison between the dark J-V characteristics of the bench mark system P3HT:PCBM and the P3HT:PbS blends allows us to conclude that a larger leakage current and a more efficient recombination are the major factors responsible for the larger losses in the hybrid system.

  18. Enhancement of the photovoltaic performance in P3HT: PbS hybrid solar cells using small size PbS quantum dots

    International Nuclear Information System (INIS)

    Firdaus, Yuliar; Van der Auweraer, Mark; Vandenplas, Erwin; Gehlhaar, Robert; Cheyns, David; Justo, Yolanda; Hens, Zeger

    2014-01-01

    Different approaches of surface modification of the quantum dots (QDs), namely, solution-phase (octylamine, octanethiol) and post-deposition (acetic acid, 1,4-benzenedithiol) ligand exchange were used in the fabrication of hybrid bulk heterojunction solar cell containing poly (3-hexylthiophene) (P3HT) and small (2.4 nm) PbS QDs. We show that replacing oleic acid by shorter chain ligands improves the figures of merit of the solar cells. This can possibly be attributed to a combination of a reduced thickness of the barrier for electron transfer and an optimized phase separation. The best results were obtained for post-deposition ligand exchange by 1,4-benzenedithiol, which improves the power conversion efficiency of solar cells based on a bulk heterojunction of lead sulfide (PbS) QDs and P3HT up to two orders of magnitude over previously reported hybrid cells based on a bulk heterojunction of P3HT:PbS QDs, where the QDs are capped by acetic acid ligands. The optimal performance was obtained for solar cells with 69 wt. % PbS QDs. Besides the ligand effects, the improvement was attributed to the formation of an energetically favorable bulk heterojunction with P3HT, when small size (2.4 nm) PbS QDs were used. Dark current density-voltage (J-V) measurements carried out on the device provided insight into the working mechanism: the comparison between the dark J-V characteristics of the bench mark system P3HT:PCBM and the P3HT:PbS blends allows us to conclude that a larger leakage current and a more efficient recombination are the major factors responsible for the larger losses in the hybrid system

  19. Study of structural and optical properties of PbS thin films

    Science.gov (United States)

    Homraruen, T.; Sudswasd, Y.; Sorod, R.; Kayunkid, N.; Yindeesuk, W.

    2018-03-01

    This research aimed to synthesize lead sulfide (PbS) thin films on glass slides using the successive ion layer absorption and reaction (SILAR) method. We studied the optical properties and structure of PbS thin films by changing the number of dipping cycles and the concentration of precursor solution. The results of this experiment show that different conditions have a considerable influence on the thickness and absorbance of the films. When the number of dipping cycles and the concentration of the solution are increased, film thickness and absorbance tend to become higher. The xrays diffraction pattern showed all the diffraction peaks which confirmed the face center cubic and the structure of PbS had identified. Grain size computation was used to confirm how much these conditions could be affected.

  20. PbS Thin Films for Photovoltaic Applications Obtained by Non-Traditional Chemical Bath Deposition

    Directory of Open Access Journals (Sweden)

    Pérez-García Claudia Elena

    2015-01-01

    Full Text Available To optimize cost-efficiency relation for thin film solar cells, we explore the recently developed versions of chemical deposition of semiconductor films, together with classic CBD (Chemical Bath Deposition: SILAR (Successive Ionic Layer Adsorption and Reaction and PCBD (Photo Chemical Bath Deposition, all of them ammonia-free and ecologically friendly. The films of CdS and PbS were made, and experimental solar cells with CdS window layer and PbS absorber elaborated. We found that band gap of PbS films can be monitored by deposition process due to porosity-induced quantum confinement which depends on the parameters of the process. We expect that the techniques employed can be successfully used for production of optoelectronic devices.

  1. Deposition of Cu-doped PbS thin films with low resistivity using DC sputtering

    Science.gov (United States)

    Soetedjo, Hariyadi; Siswanto, Bambang; Aziz, Ihwanul; Sudjatmoko

    2018-03-01

    Investigation of the electrical resistivity of Cu-doped PbS thin films has been carried out. The films were prepared using a DC sputtering technique. The doping was achieved by introducing the Cu dopant plate material directly on the surface of the PbS sputtering target plate. SEM-EDX data shows the Cu concentration in the PbS film to be proportional to the Cu plate diameter. The XRD pattern indicates the film is in crystalline cubic form. The Hall effect measurement shows that Cu doping yields an increase in the carrier concentration to 3.55 × 1019 cm-3 and a significant decrease in electrical resistivity. The lowest resistivity obtained was 0.13 Ωcm for a Cu concentration of 18.5%. Preferential orientation of (1 1 1) and (2 0 0) occurs during deposition.

  2. A photodiode based on PbS nanocrystallites for FYTRONIX solar panel automatic tracking controller

    Science.gov (United States)

    Wageh, S.; Farooq, W. A.; Tataroğlu, A.; Dere, A.; Al-Sehemi, Abdullah G.; Al-Ghamdi, Ahmed A.; Yakuphanoglu, F.

    2017-12-01

    The structural, optical and photoelectrical properties of the fabricated Al/PbS/p-Si/Al photodiode based on PbS nanocrystallites were investigated. The PbS nanocrystallites were characterized by X-ray diffraction (XRD), UV-VIS-NIR, Infrared and Raman spectroscopy. The XRD diffraction peaks show that the prepared PbS nanostructure is in high crystalline state. Various electrical parameters of the prepared photodiode were analyzed from the electrical characteristics based on I-V and C-V-G. The photodiode has a high rectification ratio of 5.85×104 at dark and ±4 V. Moreover, The photocurrent results indicate a strong photovoltaic behavior. The frequency dependence of capacitance and conductance characteristics was attributed to depletion region behavior of the photodiode. The diode was used to control solar panel power automatic tracking controller in dual axis. The fabricated photodiode works as a photosensor to control Solar tracking systems.

  3. γ-ray radiation effect on properties of straw powder/PBS composite

    International Nuclear Information System (INIS)

    Yang Mingcheng; Luo Yongquan; Liu Wentao; Zhu Jun; Guo Dongquan; Li Zhaopeng; Gen Feng; Qu Lingbo

    2013-01-01

    Background: In recent years, with decreasing global fossil resources and increasing 'white pollution', renewable and biodegradable materials attract more and more attentions. Poly (butylene succinate) (PBS) has good mechanical property, biodegradability and processing performance, which is the focus of hot topics in the study of biodegradable plastic materials, however, being soft and of high cost, it is still limited in application range. Purpose: In order to improve the mechanical and thermal properties, a series of wheat straw powder/PBS composites were prepared by melt extrusion, and then the 60 Co-y ray was directly utilized to irradiate the straw powder/PBS composite. Methods: The influence of TAIC (triallyl isocyanurate) radiation absorbed dose and radiation sensitizer on the mechanical property and thermal performance of straw powder/PBS composite was investigated, and the impact fracture surface morphology of the composite was observed by SEM (scanning electron microscope). Results: The tensile strength and flexural strength were enhanced with increasing radiation dosage, and then tend to be stable, the heat distortion temperature also increased but not significantly with increasing radiation dosage. The results show that when TAIC content is 2%, with straw powder/PBS composite irradiated by 30-kGy dose, the tensile strength and flexural strength are increased by 26% and 39.8%, respectively. Conclusion: The radiation modification of composite material has no effect on thermal stability, but do improve the tensile strength and flexural strength when up to 2% of TAIC is integrated and irradiated by certain dose. The interface cohesiveness between straw powder and PBS is strengthened after radiation. (authors)

  4. Controlled self-assembly of PbS nanoparticles into macrostar-like hierarchical structures

    International Nuclear Information System (INIS)

    Li, Guowei; Li, Changsheng; Tang, Hua; Cao, Kesheng; Chen, Juan

    2011-01-01

    Graphical abstract: The aggregation and rotation of nanoparticles to adopt parallel orientations in three dimensions was indirectly illustrated by TEM and HRTEM images. Highlights: → Macrostar-like PbS hierarchical structures was successfully synthesized by a simple hydrothermal method and mesostars were assembled from the PbS nanocube building blocks with edge lengths of about 100 nm. → Ostwald-ripening-assisted oriented attachment is believed to play a key role in the growth behavior of novel 3D structures. → Optical properties indicating few defects on the surface of the PbS structure and exhibit large blue-shifts compared to bulk PbS. -- Abstract: The synthesis of macrostar-like PbS hierarchical structures by a simple hydrothermal method at 180 o C for 24 h is proven successful with the assistance of a new surfactant called tetrabutylammonium bromide (TBAB). The as-obtained product is characterized by means of X-ray powder diffraction, field emission scanning electron microscopy, energy dispersive spectrometry, high resolution transmission electron microscopy, and selected area electron diffraction. The presence of TBAB and NaF plays an important role in the formation of PbS macrostructures. Ostwald-ripening-assisted oriented attachment is believed to play a key role in the growth behavior of novel 3D structures. As such, a possible self-assembly mechanism is proposed to explain the formation of the said structures. The present study aims to introduce new insights into understanding the formation process of such unique hierarchical superstructures.

  5. Unknown Aspects of Self-Assembly of PbS Microscale Superstructures

    Science.gov (United States)

    Querejeta-Fernández, Ana; Hernández-Garrido, Juan C.; Yang, Hengxi; Zhou, Yunlong; Varela, Aurea; Parras, Marina; Calvino-Gámez, José J.; González-Calbet, Jose M.; Green, Peter F.; Kotov, Nicholas A.

    2012-01-01

    A lot of interesting and sophisticated examples of nanoparticle (NP) self-assembly (SA) are known. From both fundamental and technological standpoints this field requires advancements in three principle directions: a) understanding the mechanism and driving forces of three-dimensional (3D) SA with both nano- and micro-levels of organization; b) understanding of disassembly/deconstruction processes; and c) finding synthetic methods of assembly into continuous superstructures without insulating barriers. From this perspective, we investigated the formation of well-known star-like PbS superstructures and found a number of previously unknown or overlooked aspects that can advance the knowledge of NP self-assembly in these three directions. The primary one is that the formation of large seemingly monocrystalline PbS superstructures with multiple levels of octahedral symmetry can be explained only by SA of small octahedral NPs. We found five distinct periods in the formation PbS hyperbranched stars: 1) nucleation of early PbS NPs with an average diameter of 31 nm; 2) assembly into 100–500 nm octahedral mesocrystals; 3) assembly into 1000–2500 nm hyperbranched stars; 4) assembly and ionic recrystallization into six-arm rods accompanied by disappearance of fine nanoscale structure; 5) deconstruction into rods and cubooctahedral NPs. The switches in assembly patterns between the periods occur due to variable dominance of pattern–determining forces that include vander Waals and electrostatic (charge-charge, dipole-dipole, and polarization) interactions. The superstructure deconstruction is triggered by chemical changes in the deep eutectic solvent (DES) used as the media. PbS superstructures can be excellent models for fundamental studies of nanoscale organization and SA manufacturing of (opto)electronics and energy harvesting devices which require organization of PbS components at multiple scales. PMID:22515512

  6. High-contrast MacNeille-PBS-based LCOS projection systems

    Science.gov (United States)

    Chen, Jianmin; Robinson, Michael G.; Sharp, Gary D.

    2005-04-01

    Contrast limits are investigated for MacNeille PBS based LCOS projection systems that use retarder stack filters (RSF). The two contributing factors are considered separately; namely the color management system and the panel port. To enhance performance of the former, skew ray compensated RSFs are introduced. For the latter, a general methodology is presented to optimize contrast by compensating the LCOS panel. It is shown that the orientation of the LCOS panel and compensator, relative to the MacNeille PBS, is critical. The significant impact of AR coating performance on system contrast is also revealed. A high contrast architecture will be presented by way of example.

  7. A Survey of Technologies Supporting Virtual Project Based Learning

    DEFF Research Database (Denmark)

    Dirckinck-Holmfeld, Lone

    2002-01-01

    This paper describes a survey of technologies and to what extent they support virtual project based learning. The paper argues that a survey of learning technologies should be related to concrete learning tasks and processes. Problem oriented project pedagogy (POPP) is discussed, and a framework...... for evaluation is proposed where negotiation of meaning, coordination and resource management are identified as the key concepts in virtual project based learning. Three e-learning systems are selected for the survey, Virtual-U, Lotus Learningspace and Lotus Quickplace, as each system offers different strategies...... for e-learning. The paper concludes that virtual project based learning may benefit from facilities of all these systems....

  8. DEVELOPMENT MODEL OF PATISSERIE PROJECT-BASED LEARNING

    OpenAIRE

    Ana Ana; Lutfhiyah Nurlaela

    2013-01-01

    The study aims to find a model of patisserie project-based learning with production approach that can improve effectiveness of patisserie learning. Delphi Technique, Cohen's Kappa and percentages of agreements were used to assess model of patisserie project based learning. Data collection techniques employed in the study were questionnaire, check list worksheet, observation, and interview sheets. Subjects were 13 lectures of expertise food and nutrition and 91 students of Food and Nutrition ...

  9. SU-E-T-266: Proton PBS Plan Design and Robustness Evaluation for Head and Neck Cancers

    International Nuclear Information System (INIS)

    Liang, X; Tang, S; Zhai, H; Kirk, M; Kalbasi, A; Lin, A; Ahn, P; Tochner, Z; McDonough, J; Both, S

    2014-01-01

    Purpose: To describe a newly designed proton pencil beam scanning (PBS) planning technique for radiotherapy of patients with bilateral oropharyngeal cancer, and to assess plan robustness. Methods: We treated 10 patients with proton PBS plans using 2 posterior oblique field (2F PBS) comprised of 80% single-field uniform dose (SFUD) and 20% intensity-modulated proton therapy (IMPT). All patients underwent weekly CT scans for verification. Using dosimetric indicators for both targets and organs at risk (OARs), we quantitatively compared initial plans and verification plans using student t-tests. We created a second proton PBS plan for each patient using 2 posterior oblique plus 1 anterior field comprised of 100% SFUD (3F PBS). We assessed plan robustness for both proton plan groups, as well as a photon volumetric modulated arc therapy (VMAT) plan group by comparing initial and verification plans. Results: The 2F PBS plans were not robust in target coverage. D98% for clinical target volume (CTV) degraded from 100% to 96% on average, with maximum change Δ D98% of −24%. Two patients were moved to photon VMAT treatment due to insufficient CTV coverage on verification plans. Plan robustness was especially weak in the low-anterior neck. The 3F PBS plans, however, demonstrated robust target coverage, which was comparable to the VMAT photon plan group. Doses to oral cavity were lower in the Proton PBS plans compared to photon VMAT plans due to no lower exit dose to the oral cavity. Conclusion: Proton PBS plans using 2 posterior oblique fields were not robust for CTV coverage, due to variable positioning of redundant soft tissue in the posterior neck. We designed 3-field proton PBS plans using an anterior field to avoid long heterogeneous paths in the low neck. These 3-field proton PBS plans had significantly improved plan robustness, and the robustness is comparable to VMAT photon plans

  10. 77 FR 35393 - Federal Management Regulation; FMR Bulletin PBS-2012-03; Redesignations of Federal Buildings

    Science.gov (United States)

    2012-06-13

    ... Management Regulation; FMR Bulletin PBS-2012-03; Redesignations of Federal Buildings AGENCY: Public Buildings... bulletin announces the designation and redesignation of three Federal buildings. Expiration Date: This bulletin announcement expires October 31, 2012. The building designation and redesignations remains in...

  11. 76 FR 54772 - Federal Management Regulation; FMR Bulletin PBS-2011-B2; Redesignations of Federal Buildings

    Science.gov (United States)

    2011-09-02

    ... Management Regulation; FMR Bulletin PBS-2011-B2; Redesignations of Federal Buildings AGENCY: Public Buildings... announces the designation and redesignation of two Federal buildings. Expiration Date: This bulletin announcement expires January 31, 2012. The building designation and redesignation remains in effect until...

  12. 75 FR 69080 - Federal Management Regulation; FMR Bulletin PBS-2010-B5; Redesignations of Federal Buildings

    Science.gov (United States)

    2010-11-10

    ... Management Regulation; FMR Bulletin PBS-2010-B5; Redesignations of Federal Buildings AGENCY: Public Buildings... announces the designation and redesignation of two Federal buildings. DATES: Expiration Date: This bulletin announcement expires April 30, 2011. The building designation and redesignation remains in effect until...

  13. 76 FR 6792 - Federal Management Regulation; FMR Bulletin PBS-2011-B1; Redesignations of Federal Buildings

    Science.gov (United States)

    2011-02-08

    ... Management Regulation; FMR Bulletin PBS-2011-B1; Redesignations of Federal Buildings AGENCY: Public Buildings... announces the redesignations of three Federal buildings. DATES: Expiration Date: This bulletin announcement expires June 30, 2011. The building redesignations remain in effect until canceled or superseded by...

  14. 75 FR 44264 - Federal Management Regulation; FMR Bulletin PBS-2010-B4; Redesignation of Federal Building

    Science.gov (United States)

    2010-07-28

    ... Management Regulation; FMR Bulletin PBS-2010-B4; Redesignation of Federal Building AGENCY: Public Buildings... announces the redesignation of a Federal building. DATES: Expiration Date: This bulletin expires December 31, 2010. However, the building redesignation announced by this bulletin will remain in effect until...

  15. Overcoming the Cut-Off Charge Transfer Bandgaps at the PbS Quantum Dot Interface

    KAUST Repository

    El-Ballouli, Ala'a O.

    2015-11-17

    Light harvesting from large size of semiconductor PbS quantum dots (QDs) with a bandgap of less than 1 eV is one of the greatest challenges precluding the development of PbS QD-based solar cells because the interfacial charge transfer (CT) from such QDs to the most commonly used electron acceptor materials is very inefficient, if it occurs at all. Thus, an alternative electron-accepting unit with a new driving force for CT is urgently needed to harvest the light from large-sized PbS QDs. Here, a cationic porphyrin is utilized as a new electron acceptor unit with unique features that bring the donor–acceptor components into close molecular proximity, allowing ultrafast and efficient electron transfer for QDs of all sizes, as inferred from the drastic photoluminescence quenching and the ultrafast formation of the porphyrin anionic species. The time-resolved results clearly demonstrate the possibility of modulating the electron transfer process between PbS QDs and porphyrin moieties not only by the size quantization effect but also by the interfacial electrostatic interaction between the positively charged porphyrin and the negatively charged QDs. This approach provides a new pathway for engineering QD-based solar cells that make the best use of the diverse photons making up the Sun\\'s broad irradiance spectrum.

  16. "In the Footsteps of Alexander the Great" PBS Series. Teacher's Guide.

    Science.gov (United States)

    Corporation for Public Broadcasting, Washington, DC.

    This teacher's guide correlates with the Public Broadcasting Service (PBS) television series "In the Footsteps of Alexander the Great" hosted by historian Michael Wood. The four episodes of the series are entitled: "Son of God"; "Lord of Asia"; "Across the Hindu Kush"; and "To the Ends of the…

  17. Opto-electronics of PbS quantum dot and narrow bandgap polymer blends

    NARCIS (Netherlands)

    Kahmann, Simon; Mura, Andrea; Protesescu, Loredana; Kovalenko, Maksym V.; Brabec, Christoph J.; Loi, Maria A.

    2015-01-01

    Here we report on the interaction between the narrow bandgap polymer [2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta-[2,1-b;3,4-b]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and lead sulphide (PbS) colloidal quantum dots (CQDs) upon photoexcitation. We show that the presence of both materials

  18. Overcoming the Cut-Off Charge Transfer Bandgaps at the PbS Quantum Dot Interface

    KAUST Repository

    El-Ballouli, Ala'a O.; Alarousu, Erkki; Kirmani, Ahmad R.; Amassian, Aram; Bakr, Osman; Mohammed, Omar F.

    2015-01-01

    Light harvesting from large size of semiconductor PbS quantum dots (QDs) with a bandgap of less than 1 eV is one of the greatest challenges precluding the development of PbS QD-based solar cells because the interfacial charge transfer (CT) from such QDs to the most commonly used electron acceptor materials is very inefficient, if it occurs at all. Thus, an alternative electron-accepting unit with a new driving force for CT is urgently needed to harvest the light from large-sized PbS QDs. Here, a cationic porphyrin is utilized as a new electron acceptor unit with unique features that bring the donor–acceptor components into close molecular proximity, allowing ultrafast and efficient electron transfer for QDs of all sizes, as inferred from the drastic photoluminescence quenching and the ultrafast formation of the porphyrin anionic species. The time-resolved results clearly demonstrate the possibility of modulating the electron transfer process between PbS QDs and porphyrin moieties not only by the size quantization effect but also by the interfacial electrostatic interaction between the positively charged porphyrin and the negatively charged QDs. This approach provides a new pathway for engineering QD-based solar cells that make the best use of the diverse photons making up the Sun's broad irradiance spectrum.

  19. B1-B2 phase transition mechanism and pathway of PbS under pressure

    Science.gov (United States)

    Adeleke, Adebayo A.; Yao, Yansun

    2018-03-01

    Experimental studies at finite Pressure-Temperature (P-T) conditions and a theoretical study at 0 K of the phase transition in lead sulphide (PbS) have been inconclusive. Many studies that have been done to understand structural transformation in PbS can broadly be classified into two main ideological streams—one with Pnma and another with Cmcm orthorhombic intermediate phase. To foster better understanding of this phenomenon, we present the result of the first-principles study of phase transition in PbS at finite temperature. We employed the particle swarm-intelligence optimization algorithm for the 0 K structure search and first-principles metadynamics simulations to study the phase transition pathway of PbS from the ambient pressure, 0 K Fm-3m structure to the high-pressure Pm-3m phase under experimentally achievable P-T conditions. Significantly, our calculation shows that both streams are achievable under specific P-T conditions. We further uncover new tetragonal and monoclinic structures of PbS with space group P21/c and I41/amd, respectively. We propose the P21/c and I41/amd as a precursor phase to the Pnma and Cmcm phases, respectively. We investigated the stability of the new structures and found them to be dynamically stable at their stability pressure range. Electronic structure calculations reveal that both P21/c and I41/amd phases are semiconducting with direct and indirect bandgap energies of 0.69(5) eV and 0.97(3) eV, respectively. In general, both P21/c and I41/amd phases were found to be energetically competitive with their respective orthorhombic successors.

  20. Monitoring results of PBS vehicles in South Africa in terms of productivity, safety and road wear performance

    CSIR Research Space (South Africa)

    Nordengen, Paul A

    2013-07-01

    Full Text Available As part of a Performance-Based Standards (PBS) research programme for heavy vehicles in South Africa, a need was identified to design, manufacture and operate a number of PBS or Smart Truck demonstration vehicles in order to gain practical...

  1. Initiative to introduce a performance-based standards (PBS) approach for heavy vehicle design and operations in South Africa

    CSIR Research Space (South Africa)

    Nordengen, Paul A

    2008-05-01

    Full Text Available The introduction of PBS for heavy vehicles in South Africa was first identified in the National Overload Control Strategy as a potential concession of a proposed Self-regulation initiative. In August 2004 a PBS committee was established...

  2. Influence of PbS nanoparticle polymer coating on their aggregation behavior and toxicity to the green algae Dunaliella salina

    International Nuclear Information System (INIS)

    Zamani, Hajar; Moradshahi, Ali; Jahromi, Hamed Dehdashti; Sheikhi, Mohammad Hosein

    2014-01-01

    Highlights: • Lead sulfide nanoparticles (PbS NPs) are toxic to D. salina. • Gum-Arabic coating alters the toxicity of PbS NPs. • Cell-NPs agglomerates and lipid peroxidation could explain the toxicity of PbS NPs. • Shading effect and dissolution do not seem to contribute to the toxicity of PbS NPs. • Particle–particle interaction was reduced by coating; therefore, PbS NPs were stabilized in the culture media. - Abstract: The potential hazards of nanoparticles (NPs) to the environment and to living organisms need to be considered for a safe development of nanotechnology. In the present study, the potential toxic effects of uncoated and gum Arabic-coated lead sulfide nanoparticles (GA-coated PbS NPs) on the growth, lipid peroxidation, reducing capacity and total carotenoid content of the hypersaline unicellular green algae Dunaliella salina were investigated. Coatings of PbS NPs with GA, as confirmed by Fourier transform infrared spectroscopy, reduced the toxicity of PbS NPs. Uncoated PbS NP toxicity to D. salina was attributed to higher algal cell-NP agglomerate formation, higher lipid peroxidation, lower content of total reducing substances and lower total carotenoid content. Low levels of Pb 2+ in the growth culture media indicate that PbS NP dissolution does not occur in the culture. Also, the addition of 100 μM Pb 2+ to the culture media had no significant (P > 0.05) effect on algal growth. The shading of light (shading effect) by PbS NPs, when simulated using activated charcoal, did not contribute to the overall toxic effect of PbS NPs which was evident by insignificant (P > 0.05) reduction in the growth and antioxidant capacity of the algae. When PbS NP aggregation in culture media (without algal cells) was followed for 60 min, uncoated form aggregated rapidly reaching aggregate sizes with hydrodynamic diameter of over 2500 nm within 60 min. Effective particle–particle interaction was reduced in the GA-coated NPs. Aggregates of about 440 nm

  3. Influence of PbS nanoparticle polymer coating on their aggregation behavior and toxicity to the green algae Dunaliella salina

    Energy Technology Data Exchange (ETDEWEB)

    Zamani, Hajar [Department of Biology, Faculty of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Moradshahi, Ali, E-mail: moradshahi@susc.ac.ir [Department of Biology, Faculty of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Jahromi, Hamed Dehdashti; Sheikhi, Mohammad Hosein [Nanotechnology Research Institute, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of)

    2014-09-15

    Highlights: • Lead sulfide nanoparticles (PbS NPs) are toxic to D. salina. • Gum-Arabic coating alters the toxicity of PbS NPs. • Cell-NPs agglomerates and lipid peroxidation could explain the toxicity of PbS NPs. • Shading effect and dissolution do not seem to contribute to the toxicity of PbS NPs. • Particle–particle interaction was reduced by coating; therefore, PbS NPs were stabilized in the culture media. - Abstract: The potential hazards of nanoparticles (NPs) to the environment and to living organisms need to be considered for a safe development of nanotechnology. In the present study, the potential toxic effects of uncoated and gum Arabic-coated lead sulfide nanoparticles (GA-coated PbS NPs) on the growth, lipid peroxidation, reducing capacity and total carotenoid content of the hypersaline unicellular green algae Dunaliella salina were investigated. Coatings of PbS NPs with GA, as confirmed by Fourier transform infrared spectroscopy, reduced the toxicity of PbS NPs. Uncoated PbS NP toxicity to D. salina was attributed to higher algal cell-NP agglomerate formation, higher lipid peroxidation, lower content of total reducing substances and lower total carotenoid content. Low levels of Pb{sup 2+} in the growth culture media indicate that PbS NP dissolution does not occur in the culture. Also, the addition of 100 μM Pb{sup 2+} to the culture media had no significant (P > 0.05) effect on algal growth. The shading of light (shading effect) by PbS NPs, when simulated using activated charcoal, did not contribute to the overall toxic effect of PbS NPs which was evident by insignificant (P > 0.05) reduction in the growth and antioxidant capacity of the algae. When PbS NP aggregation in culture media (without algal cells) was followed for 60 min, uncoated form aggregated rapidly reaching aggregate sizes with hydrodynamic diameter of over 2500 nm within 60 min. Effective particle–particle interaction was reduced in the GA-coated NPs. Aggregates of about

  4. Linking project-based production and project management temporary systems in multiple contexts: An introduction to the special edition

    Directory of Open Access Journals (Sweden)

    Leon AG Oerlemans

    2014-02-01

    Full Text Available As organisations in more and more industries look for flexible ways of production in the wake of rapidly changing market environments, project-based organising is becoming an increasingly important mode of organisation (Eisenhardt & Tabrizi, 1995. Whereas project-based organisation was traditionally mainly the domain of industries such as film making (Sorenson & Waguespack, 2006, theatre (Goodman & Goodman, 1976, and construction (Gann & Salter, 2000, a project-based mode of operation has recently pervaded many other sectors in the economy, including software development, advertising, biotechnology, consulting, emergency response, fashion, television and complex products and systems (Grabher, 2004; Hobday, 2000. This increasing prevalence is reflected in an exponentially growing body of research (Bakker, 2010, which has made marked progress in areas such as project-based learning (Prencipe & Tell, 2001, project-based innovation (Eisenhardt & Tabrizi, 1995 and project-based careers (Jones, 1996. As a consequence, research on project organisation has moved from being a narrow specialty domain toward being a broad research paradigm, attending to a broad audience in organisation science and beyond (Sydow et al., 2004. In a fairly recent review paper, Bakker (2010 shows that in the period 1988–2008 scholarly attention, as indicated by publications in books and ISI-indexed journals, grew exponentially (see Figure 1. Comparing the number of publications in the period 1988-1998 with the period 1998–2008, he observed an increase of almost 340%.

  5. Synthesis of star-shaped lead sulfide (PbS) nanomaterials and theirs gas-sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Song, Chengwen; Sun, Menghan; Yin, Yanyan; Xiao, Jingkun; Dong, Wei; Li, Chen; Zhang, Li, E-mail: chengwensong@dlmu.edu.cn [College of Environmental Science and Engineering, Dalian Maritime University, Dalian(China)

    2016-11-15

    Star-shaped PbS nanomaterials are synthesized by a hydrothermal method. Morphology and structure of the PbS nanomaterials are analyzed by SEM, HRTEM and XRD. Gas-sensing properties of the as-prepared PbS sensor are also systematically investigated. The results show star-shaped PbS nanostructure consists of four symmetric arms in the same plane and demonstrate good crystallinity. With the increase of ethanol concentration, the sensitivity of the PbS sensor significantly increases and demonstrates an almost linear relationship at the optimal operating temperature of 400 deg C. Moreover, the fast response-recovery towards ethanol is also observed, which indicates its great potential on ethanol detection. (author)

  6. Synthesis of star-shaped lead sulfide (PbS) nanomaterials and theirs gas-sensing properties

    International Nuclear Information System (INIS)

    Song, Chengwen; Sun, Menghan; Yin, Yanyan; Xiao, Jingkun; Dong, Wei; Li, Chen; Zhang, Li

    2016-01-01

    Star-shaped PbS nanomaterials are synthesized by a hydrothermal method. Morphology and structure of the PbS nanomaterials are analyzed by SEM, HRTEM and XRD. Gas-sensing properties of the as-prepared PbS sensor are also systematically investigated. The results show star-shaped PbS nanostructure consists of four symmetric arms in the same plane and demonstrate good crystallinity. With the increase of ethanol concentration, the sensitivity of the PbS sensor significantly increases and demonstrates an almost linear relationship at the optimal operating temperature of 400 deg C. Moreover, the fast response-recovery towards ethanol is also observed, which indicates its great potential on ethanol detection. (author)

  7. A Study of Creativity in CaC[subscript 2] Steamship-Derived STEM Project-Based Learning

    Science.gov (United States)

    Lou, Shi-Jer; Chou, Yung-Chieh; Shih, Ru-Chu; Chung, Chih-Chao

    2017-01-01

    This study mainly aimed to explore the effects of project-based learning (PBL) integrated into science, technology, engineering and mathematics (STEM) activities and to analyze the creativity displayed by junior high school students while performing these activities. With a quasi-experimental design, 60 ninth-grade students from a junior high…

  8. The Effect of a Graph-Oriented Computer-Assisted Project-Based Learning Environment on Argumentation Skills

    Science.gov (United States)

    Hsu, P. -S.; Van Dyke, M.; Chen, Y.; Smith, T. J.

    2015-01-01

    The purpose of this quasi-experimental study was to explore how seventh graders in a suburban school in the United States developed argumentation skills and science knowledge in a project-based learning environment that incorporated a graph-oriented, computer-assisted application. A total of 54 students (three classes) comprised this treatment…

  9. All-solution-processed PbS quantum dot solar modules

    Science.gov (United States)

    Jang, Jihoon; Shim, Hyung Cheoul; Ju, Yeonkyeong; Song, Jung Hoon; An, Hyejin; Yu, Jong-Su; Kwak, Sun-Woo; Lee, Taik-Min; Kim, Inyoung; Jeong, Sohee

    2015-05-01

    A rapid increase in power conversion efficiencies in colloidal quantum dot (QD) solar cells has been achieved recently with lead sulphide (PbS) QDs by adapting a heterojunction architecture, which consists of small-area devices associated with a vacuum-deposited buffer layer with metal electrodes. The preparation of QD solar modules by low-cost solution processes is required to further increase the power-to-cost ratio. Herein we demonstrate all-solution-processed flexible PbS QD solar modules with a layer-by-layer architecture comprising polyethylene terephthalate (PET) substrate/indium tin oxide (ITO)/titanium oxide (TiO2)/PbS QD/poly(3-hexylthiophene) (P3HT)/poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS)/Ag, with an active area of up to 30 cm2, exhibiting a power conversion efficiency (PCE) of 1.3% under AM 1.5 conditions (PCE of 2.2% for a 1 cm2 unit cell). Our approach affords trade-offs between power and the active area of the photovoltaic devices, which results in a low-cost power source, and which is scalable to larger areas.A rapid increase in power conversion efficiencies in colloidal quantum dot (QD) solar cells has been achieved recently with lead sulphide (PbS) QDs by adapting a heterojunction architecture, which consists of small-area devices associated with a vacuum-deposited buffer layer with metal electrodes. The preparation of QD solar modules by low-cost solution processes is required to further increase the power-to-cost ratio. Herein we demonstrate all-solution-processed flexible PbS QD solar modules with a layer-by-layer architecture comprising polyethylene terephthalate (PET) substrate/indium tin oxide (ITO)/titanium oxide (TiO2)/PbS QD/poly(3-hexylthiophene) (P3HT)/poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS)/Ag, with an active area of up to 30 cm2, exhibiting a power conversion efficiency (PCE) of 1.3% under AM 1.5 conditions (PCE of 2.2% for a 1 cm2 unit cell). Our approach affords trade

  10. Project-based knowledge in organizing open innovation

    CERN Document Server

    Comacchio, Anna; Pizzi, Claudio

    2014-01-01

    Enriching understanding of the current theoretical debate on project-based open innovation, ‘Project-based Knowledge in Organizing Open Innovation’ draws on innovation management literature and knowledge-based perspectives to investigate the relationship between knowledge development at project level and the strategic organization of open innovation. Addressing the still open issue of how the firm level should be complemented by studies at the project level of analysis, this book provides theoretical and empirical arguments on the advantages of a more fine-grained level of analysis to understand how firms organize their innovation processes across boundaries. The book also addresses the emerging interest in the management literature on project-based organizations, and on the relevance of project forms of organizing in a knowledge-based economy. Through field research in different industrial settings , this book provides empirical evidence on how firms design open innovation project-by-project and it will ...

  11. The Effectiveness of Project Based Learning in Trigonometry

    Science.gov (United States)

    Gerhana, M. T. C.; Mardiyana, M.; Pramudya, I.

    2017-09-01

    This research aimed to explore the effectiveness of Project-Based Learning (PjBL) with scientific approach viewed from interpersonal intelligence toward students’ achievement learning in mathematics. This research employed quasi experimental research. The subjects of this research were grade X MIPA students in Sleman Yogyakarta. The result of the research showed that project-based learning model is more effective to generate students’ mathematics learning achievement that classical model with scientific approach. This is because in PjBL model students are more able to think actively and creatively. Students are faced with a pleasant atmosphere to solve a problem in everyday life. The use of project-based learning model is expected to be the choice of teachers to improve mathematics education.

  12. Orthogonally Based Digital Content Management Applicable to Projects-bases

    Directory of Open Access Journals (Sweden)

    Daniel MILODIN

    2009-01-01

    Full Text Available There is defined the concept of digital content. The requirements of an efficient management of the digital content are established. There are listed the quality characteristics of digital content. Orthogonality indicators of digital content are built up. They are meant to measure the image, the sound as well as the text orthogonality as well. Projects-base concept is introduced. There is presented the model of structuring the content in order to maximize orthogonality via a convergent iterative process. The model is instantiated for the digital content of a projects-base. It is introduced the application used to test the model. The paper ends with conclusions.

  13. Enhancement of Electron Transfer Efficiency in Solar Cells Based on PbS QD/N719 Dye Cosensitizers

    Directory of Open Access Journals (Sweden)

    Yanyan Gao

    2012-01-01

    Full Text Available Cosensitized solar cells (CSSCs have recently become an active subject in the field of sensitized solar cells (SSCs due to their increasing electronic utilization. However, because of the dye molecules, layer must be single, dye-SSCs cannot be co-sensitized with two different dyes to form two different molecules layer. But it is possible to be cosensitized with quantum dots (QDs and dyes. Here we designed novel photoanode architecture, namely, PbS QDs and N719 dyes are used as co-sensitizers of the TiO2 mesoporous film. The experimental result shows that PbS QDs/N719 dyes co-sensitized structure can make PbS QDs and N719 dyes mutual improvement. Taking the advantage of PbS not only achieved higher transfer efficiency of photo-excited electron, but also achieved obviously wider range and higher intensity of absorption. The PbS QDs which have been deposited on the TiO2 film was coated by N719 dyes, which can effectively prevent PbS QDs from corroding by I-/I3-electrolyte and light. As we expected, the solar energy-conversion efficiency which is showed by CSSCs fabricated following these photoanodes is relatively higher than the PbS QDs or N719 dyes, single-sensitized solar cells under the illumination of one sun.

  14. Tn5-induced pBS286 plasmid mutations blocking early stages of napthalene oxidation

    International Nuclear Information System (INIS)

    Kosheleva, I.A.; Tsoi, T.V.; Ivashina, T.V.; Selifonov, S.A.; Starovoitov, I.I.; Boronin, A.M.

    1988-01-01

    The authors present data on the further analysis of the structural and functional organization of the nah region of plasmid pBS286 controlling the constitutive oxidation of naphthalene by Pseudomonas putida cells. They have studied Tn5-induced mutations blocking early stages of naphthalene oxidation. They present and discuss data providing evidence that, in contrast to plasmid NAH7, the mechanism of regulation of the nahl operon of plasmid NPL-1, the parent plasmid of plasmid pBS286, with inducible synthesis of naphthalene dioxygenase can include elements of a negative control with participation of the regulatory locus R, located proximal to the structural nah genes and closely linked to or overlapped by the inverted control DNA segment (4.2 kb). They also present data on the possibility of regulation of the activity of the catechol-splitting meta-pathway genes with the participation of products of early stages of naphthalene oxidation

  15. The deposition of highly uniform and adhesive nanocrystalline PbS film from solution

    International Nuclear Information System (INIS)

    Yang Yujun; Hu Shengshui

    2008-01-01

    Mirror-like PbS films have been deposited by chemical deposition on glass substrates from alkaline chemical bath containing lead nitrate, sodium thiosulfate and 1-thioglycerol, which was used to catalyze the hydrolysis of thiosulfate. Nanostructure characterization was carried out by x-ray diffraction and scanning electron microscopy in order to determine the average crystallite size (61 nm) and study the surface morphologies of the as-deposited films

  16. Phase transformation and conductivity in nanocrystal PbS under pressure

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Gerward, Leif; Secco, R.

    2000-01-01

    The grain-size effect on the phase transition induced by pressure in PbS was studied by in situ high-pressure electrical resistance and synchrotron radiation x-ray powder diffraction measurements. The mean transition pressure of the B1-to-B16 phase transformation was found to be 6.3±1.3 GPa in 8...... in terms of a decrease of energy band gap with increasing pressure. ©2000 American Institute of Physics....

  17. Luminescence and transient lifetime studies for energy transfer of PbS QD films

    Science.gov (United States)

    Wang, Joanna S.; Ullrich, Bruno; Dass, Chandriker K.; Das, Anirban; Wai, Chien M.; Brown, Gail J.; Hendrickson, Joshua R.

    2017-08-01

    Quantum confined semiconductor materials in colloidal form have drawn great attention in scientific communities due to the size-tunability, which controls their optical properties. PbS quantum dots (QDs) are exciting candidates for quantum optics, particularly due to the control of the QD sizes during the synthetic process enabling the realization of precisely tunable emission properties in the near-infrared region. Differently sized pairs of PbS QDs were deposited onto glass substrates to form thin films using supercritical CO2 (sc-CO2) deposition and solvent deposition methods (SDM). The fluorescence and photoluminescence (PL) spectra obtained from these closely packed films prepared by the sc-CO2 method reveal effective Förster resonance energy transfer (FRET) between two different sized dots, while the films composed of three different QD sizes show an even more effective FRET from the smallest to the largest ones. Energy transfer can be observed more directly by temporally resolved PL decay of mixed dots. By means of transient lifetime measurements, a mixed PbS film with 3.1 and 4.7 nm QDs was studied for FRET by time correlated single photon counting. The PL peak of the 3.1 nm QDs is quenched with respect to the emission of the 4.7 nm QDs and decays faster, and the best fit for the lifetime (decay constant)-1 is a biexponential decay mode. The long wavelength decay (4.7 nm QDs) is best fit by a mono-exponential equation. More theoretical and experimental work is required for a thorough understanding of the radiative lifetimes of PbS QDs in mixed QD systems.

  18. In Situ Passivation for Efficient PbS Quantum Dot Solar Cells by Precursor Engineering.

    Science.gov (United States)

    Wang, Yongjie; Lu, Kunyuan; Han, Lu; Liu, Zeke; Shi, Guozheng; Fang, Honghua; Chen, Si; Wu, Tian; Yang, Fan; Gu, Mengfan; Zhou, Sijie; Ling, Xufeng; Tang, Xun; Zheng, Jiawei; Loi, Maria Antonietta; Ma, Wanli

    2018-04-01

    Current efforts on lead sulfide quantum dot (PbS QD) solar cells are mostly paid to the device architecture engineering and postsynthetic surface modification, while very rare work regarding the optimization of PbS synthesis is reported. Here, PbS QDs are successfully synthesized using PbO and PbAc 2  · 3H 2 O as the lead sources. QD solar cells based on PbAc-PbS have demonstrated a high power conversion efficiency (PCE) of 10.82% (and independently certificated values of 10.62%), which is significantly higher than the PCE of 9.39% for PbO-PbS QD based ones. For the first time, systematic investigations are carried out on the effect of lead precursor engineering on the device performance. It is revealed that acetate can act as an efficient capping ligands together with oleic acid, providing better surface coverage and replace some of the harmful hydroxyl (OH) ligands during the synthesis. Then the acetate on the surface can be exchanged by iodide and lead to desired passivation. This work demonstrates that the precursor engineering has great potential in performance improvement. It is also pointed out that the initial synthesis is an often neglected but critical stage and has abundant room for optimization to further improve the quality of the resultant QDs, leading to breakthrough efficiency. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Sulfide precursor concentration and lead source effect on PbS thin films properties

    International Nuclear Information System (INIS)

    Beddek, L.; Messaoudi, M.; Attaf, N.; Aida, M.S.; Bougdira, J.

    2016-01-01

    Lead sulfide (PbS) thin films were synthesized using chemical bath deposition (CBD). Bath solutions are formed of various concentrations of thiourea, sulfide source, ranged from 0.6 to 1.2 M and two different salts as Pb source (lead acetate and lead nitrate). From the growth mechanism, we inferred that PbS is formed through the ion by ion process when using acetate lead source, while, using nitrate source yields to films growth through the complex-decomposition process. Due to the difference in the involved growth process, lead acetate produces films with larger crystallite size (from 4 to 16 nm), smooth and dense films. However, lead nitrate produces rough films with smaller crystallite size (from 1 to 4 nm). Increasing the thiourea concentration results in crystallinity improvement when using lead acetate and, oppositely, in crystallinity degradation when using lead nitrate. Due to the quantum effect caused by the small crystallite sizes, the films optical gap is varied from 0.5 to 0.9 eV. - Highlights: • PbS thin films were synthesized by chemical bath deposition. • Ion by ion is the growth process when using the acetate lead source. • Deposition process is by complex-decomposition when using nitrate source. • Lead acetate yields to dense films with larger crystallite size. • Lead nitrate produces rough films with smaller crystallite size.

  20. Sulfide precursor concentration and lead source effect on PbS thin films properties

    Energy Technology Data Exchange (ETDEWEB)

    Beddek, L.; Messaoudi, M.; Attaf, N. [Laboratoire Couche Minces et Interfaces, Université frères Mentouri Constantine, 25000, Constantine (Algeria); Aida, M.S., E-mail: aida_salah2@yahoo.fr [Laboratoire Couche Minces et Interfaces, Université frères Mentouri Constantine, 25000, Constantine (Algeria); Bougdira, J. [Université de Lorraine, Institut Jean Lamour UMR 7198, Vandoeuvre 54506 (France)

    2016-05-05

    Lead sulfide (PbS) thin films were synthesized using chemical bath deposition (CBD). Bath solutions are formed of various concentrations of thiourea, sulfide source, ranged from 0.6 to 1.2 M and two different salts as Pb source (lead acetate and lead nitrate). From the growth mechanism, we inferred that PbS is formed through the ion by ion process when using acetate lead source, while, using nitrate source yields to films growth through the complex-decomposition process. Due to the difference in the involved growth process, lead acetate produces films with larger crystallite size (from 4 to 16 nm), smooth and dense films. However, lead nitrate produces rough films with smaller crystallite size (from 1 to 4 nm). Increasing the thiourea concentration results in crystallinity improvement when using lead acetate and, oppositely, in crystallinity degradation when using lead nitrate. Due to the quantum effect caused by the small crystallite sizes, the films optical gap is varied from 0.5 to 0.9 eV. - Highlights: • PbS thin films were synthesized by chemical bath deposition. • Ion by ion is the growth process when using the acetate lead source. • Deposition process is by complex-decomposition when using nitrate source. • Lead acetate yields to dense films with larger crystallite size. • Lead nitrate produces rough films with smaller crystallite size.

  1. Tuning light emission of PbS nanocrystals from infrared to visible range by cation exchange

    KAUST Repository

    Binetti, Enrico

    2015-10-27

    Colloidal semiconductor nanocrystals, with intense and sharp-line emission between red and near-infrared spectral regions, are of great interest for optoelectronic and bio-imaging applications. The growth of an inorganic passivation layer on nanocrystal surfaces is a common strategy to improve their chemical and optical stability and their photoluminescence quantum yield. In particular, cation exchange is a suitable approach for shell growth at the expense of the nanocrystal core size. Here, the cation exchange process is used to promote the formation of a CdS passivation layer on the surface of very small PbS nanocrystals (2.3 nm in diameter), blue shifting their optical spectra and yielding luminescent and stable nanostructures emitting in the range of 700–850 nm. Structural, morphological and compositional investigation confirms the nanocrystal size contraction after the cation-exchange process, while the PbS rock-salt crystalline phase is retained. Absorption and photoluminescence spectroscopy demonstrate the growth of a passivation layer with a decrease of the PbS core size, as inferred by the blue-shift of the excitonic peaks. The surface passivation strongly increases the photoluminescence intensity and the excited state lifetime. In addition, the nanocrystals reveal increased stability against oxidation over time. Thanks to their absorption and emission spectral range and the slow recombination dynamics, such highly luminescent nano-objects can find interesting applications in sensitized photovoltaic cells and light-emitting devices.

  2. Chemically synthesized PbS Nano particulate thin films for a rapid NO2 gas sensor

    Directory of Open Access Journals (Sweden)

    Burungale Vishal V.

    2016-03-01

    Full Text Available Rapid NO2 gas sensor has been developed based on PbS nanoparticulate thin films synthesized by Successive Ionic Layer Adsorption and Reaction (SILAR method at different precursor concentrations. The structural and morphological properties were investigated by means of X-ray diffraction and field emission scanning electron microscope. NO2 gas sensing properties of PbS thin films deposited at different concentrations were tested. PbS film with 0.25 M precursor concentration showed the highest sensitivity. In order to optimize the operating temperature, the sensitivity of the sensor to 50 ppm NO2 gas was measured at different operating temperatures, from 50 to 200 °C. The gas sensitivity increased with an increase in operating temperature and achieved the maximum value at 150 °C, followed by a decrease in sensitivity with further increase of the operating temperature. The sensitivity was about 35 % for 50 ppm NO2 at 150 °C with rapid response time of 6 s. T90 and T10 recovery time was 97 s at this gas concentration.

  3. Deposition of Cu-doped PbS thin films with low resistivity using DC sputtering

    Directory of Open Access Journals (Sweden)

    Hariyadi Soetedjo

    2018-03-01

    Full Text Available Investigation of the electrical resistivity of Cu-doped PbS thin films has been carried out. The films were prepared using a DC sputtering technique. The doping was achieved by introducing the Cu dopant plate material directly on the surface of the PbS sputtering target plate. SEM-EDX data shows the Cu concentration in the PbS film to be proportional to the Cu plate diameter. The XRD pattern indicates the film is in crystalline cubic form. The Hall effect measurement shows that Cu doping yields an increase in the carrier concentration to 3.55 × 1019 cm−3 and a significant decrease in electrical resistivity. The lowest resistivity obtained was 0.13 Ωcm for a Cu concentration of 18.5%. Preferential orientation of (1 1 1 and (2 0 0 occurs during deposition. Keywords: Thin films, Lead sulfide, Sputtering, Resistivity, Semiconductor, Infrared

  4. Tuning light emission of PbS nanocrystals from infrared to visible range by cation exchange

    KAUST Repository

    Binetti, Enrico; Striccoli, Marinella; Sibillano, Teresa; Giannini, Cinzia; Brescia, Rosaria; Falqui, Andrea; Comparelli, Roberto; Corricelli, Michela; Tommasi, Raffaele; Agostiano, Angela; Curri, M Lucia

    2015-01-01

    Colloidal semiconductor nanocrystals, with intense and sharp-line emission between red and near-infrared spectral regions, are of great interest for optoelectronic and bio-imaging applications. The growth of an inorganic passivation layer on nanocrystal surfaces is a common strategy to improve their chemical and optical stability and their photoluminescence quantum yield. In particular, cation exchange is a suitable approach for shell growth at the expense of the nanocrystal core size. Here, the cation exchange process is used to promote the formation of a CdS passivation layer on the surface of very small PbS nanocrystals (2.3 nm in diameter), blue shifting their optical spectra and yielding luminescent and stable nanostructures emitting in the range of 700–850 nm. Structural, morphological and compositional investigation confirms the nanocrystal size contraction after the cation-exchange process, while the PbS rock-salt crystalline phase is retained. Absorption and photoluminescence spectroscopy demonstrate the growth of a passivation layer with a decrease of the PbS core size, as inferred by the blue-shift of the excitonic peaks. The surface passivation strongly increases the photoluminescence intensity and the excited state lifetime. In addition, the nanocrystals reveal increased stability against oxidation over time. Thanks to their absorption and emission spectral range and the slow recombination dynamics, such highly luminescent nano-objects can find interesting applications in sensitized photovoltaic cells and light-emitting devices.

  5. Novel Random PBS-Based Copolymers Containing Aliphatic Side Chains for Sustainable Flexible Food Packaging

    Directory of Open Access Journals (Sweden)

    Giulia Guidotti

    2017-12-01

    Full Text Available In the last decade, there has been an increased interest from the food packaging industry toward the development and application of biodegradable and biobased plastics, to contribute to the sustainable economy and to reduce the huge environmental problem afflicting the planet. In this framework, the present paper describes the synthesis of novel PBS (poly(butylene succinate-based random copolymers with different composition containing glycol sub-units characterized by alkyl pendant groups of different length. The prepared samples were subjected to molecular, thermal, diffractometric and mechanical characterization. The barrier performances to O2, CO2 and N2 gases were also evaluated, envisioning for these new materials an application in food packaging. The presence of the side alkyl groups did not alter the thermal stability, whereas it significantly reduced the sample crystallinity degree, making these materials more flexible. The barrier properties were found to be worse than PBS; however, some of them were comparable to, or even better than, those of Low Density Polyethylene (LDPE, widely employed for flexible food packaging. The entity of variations in the final properties due to copolymerization were more modest in the case of the co-unit with short side methyl groups, which, when included in the PBS crystal lattice, causes a more modest decrement of crystallinity degree.

  6. Na-A4 zeolites as host of PbS nanoparticles

    International Nuclear Information System (INIS)

    Flores A, M.; Perez S, R.; Aceves T, R.; Arizpe C, H.; Sotelo L, M.; Ramirez B, R.

    2006-01-01

    In this work we report the optical and structural properties of composite materials based on the semiconductor PbS enclosed in type A zeolite. The composite materials were obtained by chemical reaction in several steps of the zeolite in alkaline aqueous solutions containing Pb 2+ and S 2- ions successively. Three samples were prepared at temperatures of 40, 50 and 60 C during the chemical reaction with S 2- ions. The obtained materials were studied by x-ray diffraction, scanning and transmission electron microscopy, diffuse reflectance spectroscopy and photoluminescence. The experimental results show the formation of spherical-shaped PbS particles with nano metric size and cubic crystalline structure embedded in the zeolite matrix. The absorption spectra of the samples display a well defined absorption band at about 300 nm due to the PbS nanoparticles in the zeolite matrix. In addition, an absorption peak appears in the absorption spectra at about 400 nm assigned to exciton transitions. (Author)

  7. Charge Carrier Conduction Mechanism in PbS Quantum Dot Solar Cells: Electrochemical Impedance Spectroscopy Study.

    Science.gov (United States)

    Wang, Haowei; Wang, Yishan; He, Bo; Li, Weile; Sulaman, Muhammad; Xu, Junfeng; Yang, Shengyi; Tang, Yi; Zou, Bingsuo

    2016-07-20

    With its properties of bandgap tunability, low cost, and substrate compatibility, colloidal quantum dots (CQDs) are becoming promising materials for optoelectronic applications. Additionally, solution-processed organic, inorganic, and hybrid ligand-exchange technologies have been widely used in PbS CQDs solar cells, and currently the maximum certified power conversion efficiency of 9.9% has been reported by passivation treatment of molecular iodine. Presently, there are still some challenges, and the basic physical mechanism of charge carriers in CQDs-based solar cells is not clear. Electrochemical impedance spectroscopy is a monitoring technology for current by changing the frequency of applied alternating current voltage, and it provides an insight into its electrical properties that cannot be measured by direct current testing facilities. In this work, we used EIS to analyze the recombination resistance, carrier lifetime, capacitance, and conductivity of two typical PbS CQD solar cells Au/PbS-TBAl/ZnO/ITO and Au/PbS-EDT/PbS-TBAl/ZnO/ITO, in this way, to better understand the charge carriers conduction mechanism behind in PbS CQD solar cells, and it provides a guide to design high-performance quantum-dots solar cells.

  8. Tunneling effect on double potential barriers GaAs and PbS

    Science.gov (United States)

    Prastowo, S. H. B.; Supriadi, B.; Ridlo, Z. R.; Prihandono, T.

    2018-04-01

    A simple model of transport phenomenon tunnelling effect through double barrier structure was developed. In this research we concentrate on the variation of electron energy which entering double potential barriers to transmission coefficient. The barriers using semiconductor materials GaAs (Galium Arsenide) with band-gap energy 1.424 eV, distance of lattice 0.565 nm, and PbS (Lead Sulphide) with band gap energy 0.41 eV distance of lattice is 18 nm. The Analysisof tunnelling effect on double potentials GaAs and PbS using Schrodinger’s equation, continuity, and matrix propagation to get transmission coefficient. The maximum energy of electron that we use is 1.0 eV, and observable from 0.0025 eV- 1.0 eV. The shows the highest transmission coefficient is0.9982 from electron energy 0.5123eV means electron can pass the barriers with probability 99.82%. Semiconductor from materials GaAs and PbS is one of selected material to design semiconductor device because of transmission coefficient directly proportional to bias the voltage of semiconductor device. Application of the theoretical analysis of resonant tunnelling effect on double barriers was used to design and develop new structure and combination of materials for semiconductor device (diode, transistor, and integrated circuit).

  9. Project-Based Learning in Programmable Logic Controller

    Science.gov (United States)

    Seke, F. R.; Sumilat, J. M.; Kembuan, D. R. E.; Kewas, J. C.; Muchtar, H.; Ibrahim, N.

    2018-02-01

    Project-based learning is a learning method that uses project activities as the core of learning and requires student creativity in completing the project. The aims of this study is to investigate the influence of project-based learning methods on students with a high level of creativity in learning the Programmable Logic Controller (PLC). This study used experimental methods with experimental class and control class consisting of 24 students, with 12 students of high creativity and 12 students of low creativity. The application of project-based learning methods into the PLC courses combined with the level of student creativity enables the students to be directly involved in the work of the PLC project which gives them experience in utilizing PLCs for the benefit of the industry. Therefore, it’s concluded that project-based learning method is one of the superior learning methods to apply on highly creative students to PLC courses. This method can be used as an effort to improve student learning outcomes and student creativity as well as to educate prospective teachers to become reliable educators in theory and practice which will be tasked to create qualified human resources candidates in order to meet future industry needs.

  10. Change Project-Based Learning in Teacher Education in Botswana ...

    African Journals Online (AJOL)

    Environmental education (EE) and education for sustainable development (ESD) pedagogies are intricate, and to enhance learning, teacher education has to be innovative in teaching approach. This article investigates how the change project approach enhances project-based learning in practice. The investigation is ...

  11. Conflict from Teamwork in Project-Based Collaborative Learning

    Science.gov (United States)

    Chan, Lim Ha; Chen, Ching-Huei

    2010-01-01

    This study investigated the conflict occurring during teamwork among college seniors in project-based collaborative learning in a capstone course. It found that conflict emerged with poor communication, task management, and work allocation; unequal treatments among classmates; egocentricity; a clash of values; and lack of responsibility and…

  12. Adaptive Knowledge Management of Project-Based Learning

    Science.gov (United States)

    Tilchin, Oleg; Kittany, Mohamed

    2016-01-01

    The goal of an approach to Adaptive Knowledge Management (AKM) of project-based learning (PBL) is to intensify subject study through guiding, inducing, and facilitating development knowledge, accountability skills, and collaborative skills of students. Knowledge development is attained by knowledge acquisition, knowledge sharing, and knowledge…

  13. Project-Based Management Development: "The Volvo Story."

    Science.gov (United States)

    Branch, John; Smith, Bryan

    1992-01-01

    A modular group project-based approach to management development was implemented by Volvo Concessionaires (United Kingdom) in partnership with training consultants. Ingredients of its success included top-level commitment, investment in diagnosis and tailoring, and use of company-specific case studies. (SK)

  14. A Project-based Learning approach for teaching Robotics to ...

    African Journals Online (AJOL)

    In this research we used a project-based learning approach to teach robotics basics to undergraduate business computing students. The course coverage includes basic electronics, robot construction and programming using arduino. Students developed and tested a robot prototype. The project was evaluated using a ...

  15. ICT in Problem- and Project-based Learning

    DEFF Research Database (Denmark)

    Andreasen, Lars Birch; Lerche Nielsen, Jørgen

    2012-01-01

    The paper discusses how teaching and learning practices at universities can implement new information technologies, inspired by the traditions of problem- and project-based learning. The changing roles in the teacher-student relationship, and students’ development of information literacy are disc...

  16. Perceptions of Teacher Candidates Regarding Project-Based Learning

    Science.gov (United States)

    Baysura, Ozge Deniz; Altun, Sertel; Yucel-Toy, Banu

    2016-01-01

    Problem Statement: Project-based learning (PBL) is a learning and teaching approach that makes students search for new knowledge and skills, helps them overcome real-life questions, and makes them design their own studies and performances. Research in Turkey reveals that teachers are not well-informed about PBL, can not guide students in this…

  17. Implementation of a Project-Based Telecommunications Engineering Design Course

    Science.gov (United States)

    Aliakbarian, Hadi; Soh, Ping Jack; Farsi, Saeed; Xu, Hantao; Van Lil, Emmanuel H. E. M. J. C.; Nauwelaers, Bart K. J. C.; Vandenbosch, Guy A. E.; Schreurs, Dominique M. M.-P.

    2014-01-01

    This paper describes and discusses the implementation of a project-based graduate design course in telecommunications engineering. This course, which requires a combination of technical and soft skills for its completion, enables guided independent learning (GIL) and application of technical knowledge acquired from classroom learning. Its main…

  18. Introducing Project-Based Learning to Design Enterprises for Creativity

    DEFF Research Database (Denmark)

    Wang, Feng; Zhou, Chunfang; Chen, Hongbing

    2013-01-01

    This paper aims to emphasize the necessity of introducing Project-Based Learning (PBL) to design enterprises in order to foster designers creativity and facilitate innovation of design enterprises. According to the literature review, creativity can be viewed as the first stage of innovation; PBL...

  19. Quantity versus Quality in Project Based Learning Practices

    NARCIS (Netherlands)

    A. Keegan (Anne); J.R. Turner (Rodney)

    2000-01-01

    textabstractIn the midst of the turbulence wrought by the global economy, it has become common to see projects as an essential medium for achieving change. However, project based learning practices - as a subset of organizational learning practices- have not kept pace with this development. To

  20. Project Based Learning in Multi-Grade Class

    Science.gov (United States)

    Ciftci, Sabahattin; Baykan, Ayse Aysun

    2013-01-01

    The purpose of this study is to evaluate project based learning in multi-grade classes. This study, based on a student-centered learning approach, aims to analyze students' and parents' interpretations. The study was done in a primary village school belonging to the Centre of Batman, already adapting multi-grade classes in their education system,…

  1. Learning Physics through Project-Based Learning Game Techniques

    Science.gov (United States)

    Baran, Medine; Maskan, Abdulkadir; Yasar, Seyma

    2018-01-01

    The aim of the present study, in which Project and game techniques are used together, is to examine the impact of project-based learning games on students' physics achievement. Participants of the study consist of 34 9th grade students (N = 34). The data were collected using achievement tests and a questionnaire. Throughout the applications, the…

  2. The Project-Based Learning Approach in Environmental Education

    Science.gov (United States)

    Genc, Murat

    2015-01-01

    The purpose of this study is to investigate the effect of project-based learning on students' attitudes toward the environment. In the study that was performed with 39 students who take the "Environmental Education" course, attitude changes toward the environment were investigated in students who developed projects on environmental…

  3. Enhancing College Students' Life Skills through Project Based Learning

    Science.gov (United States)

    Wurdinger, Scott; Qureshi, Mariam

    2015-01-01

    This study examined whether life skills could be developed in a Project Based Learning (PBL) course. The participants were students enrolled in a graduate level PBL course. The same 35-question survey was given to students at the beginning and end of the course, and students were asked to rank their life skills using a Likert scale. Additionally,…

  4. Project-Based Learning: A Review of the Literature

    Science.gov (United States)

    Kokotsaki, Dimitra; Menzies, Victoria; Wiggins, Andy

    2016-01-01

    Project-based learning (PBL) is an active student-centred form of instruction which is characterised by students' autonomy, constructive investigations, goal-setting, collaboration, communication and reflection within real-world practices. It has been explored in various contexts and in different phases of schooling, from primary to higher…

  5. Facilitating Problem Framing in Project-Based Learning

    Science.gov (United States)

    Svihla, Vanessa; Reeve, Richard

    2016-01-01

    While problem solving is a relatively well understood process, problem framing is less well understood, particularly with regard to supporting students to learn as they frame problems. Project-based learning classrooms are an ideal setting to investigate how teachers facilitate this process. Using participant observation, this study investigated…

  6. Project-Based Learning in Geotechnics: Cooperative versus Collaborative Teamwork

    Science.gov (United States)

    Pinho-Lopes, Margarida; Macedo, Joaquim

    2016-01-01

    Since 2007/2008 project-based learning models have been used to deliver two fundamental courses on Geotechnics in University of Aveiro, Portugal. These models have evolved and have encompassed either cooperative or collaborative teamwork. Using data collected in five editions of each course (Soil Mechanics I and Soil Mechanics II), the different…

  7. Soft Assembling Project-Based Learning and Leadership in Japan

    Science.gov (United States)

    Knight, Kevin; Murphey, Tim

    2017-01-01

    In this article, we initially focus on how the conceptualization of leadership by Knight (2013a) in his leadership seminars became the basis for choosing a project-based learning (PBL) approach. We then consider how soft assembling can enhance the leadership project activities of student teams and group-work in general classes. Soft assembling…

  8. Implementing Project Based Learning Approach to Graphic Design Course

    Science.gov (United States)

    Riyanti, Menul Teguh; Erwin, Tuti Nuriah; Suriani, S. H.

    2017-01-01

    The purpose of this study was to develop a learning model based Commercial Graphic Design Drafting project-based learning approach, was chosen as a strategy in the learning product development research. University students as the target audience of this model are the students of the fifth semester Visual Communications Design Studies Program…

  9. Project-Based Learning in Electronic Technology: A Case Study

    Science.gov (United States)

    Li, Li

    2015-01-01

    A case study of project-based learning (PBL) implemented in Tianjin University of Technology and Education is presented. This multidiscipline project is innovated to meet the novel requirements of industry while keeping its traditional effectiveness in driving students to apply knowledge to practice and problem-solving. The implementation of PBL…

  10. 37 CFR 253.4 - Performance of musical compositions by PBS, NPR and other public broadcasting entities engaged in...

    Science.gov (United States)

    2010-07-01

    ... background or theme music in a PBS program: 2003-2007 $56.81 (3) For performance of such a work in a feature... music in a program of a station of PBS: 2003-2007 $4.04 (5) For the performance of such a work in a... theme music in an NPR program: 2003-2007 $5.51 (7) For the performance of such a work in a feature...

  11. 37 CFR 381.4 - Performance of musical compositions by PBS, NPR and other public broadcasting entities engaged in...

    Science.gov (United States)

    2010-07-01

    ... background or theme music in a PBS program: 2008-2012 $57.66 (3) For performance of such a work in a feature... music in a program of a station of PBS: 2008-2012 $4.10 (5) For the performance of such a work in a... theme music in an NPR program: 2008-2012 $5.59 (7) For the performance of such a work in a feature...

  12. PROJECT BASED LEARNING BERMUATAN ETNOMATEMATIKA DALAM PEMBELAJAR MATEMATIKA

    Directory of Open Access Journals (Sweden)

    I Wayan Eka Mahendra

    2017-03-01

    Full Text Available This study aims to determine differences simultaneously in motivation and mathematics learning outcomes between students taking project based learningmodel charged ethnomathematics and students who followed the conventional learning modelon the class VIII SMP Negeri 3 Abiansemalyear 2016/2017. It was a quasi experiment with a sample of 71 student obtain by using simple random sampling. The data were analyzed by one-way multivariate analysis (Manova.The results of this study indicate that there are differences in simultaneously in learning motivation and learning outcomes between students taking mathematics model project based learning charged ethnomathematics and students who followed the conventional learning model on the class VIII SMP Negeri 3 Abiansemal year 2016/2017. Besed on the research findings, junior high school teachers are suggested to improve their student learning outcome for mathematics. Teachers also need to use a learning models accurately and correctly.

  13. A Conceptualization of Knowledge Governance in Project-based Organizations

    DEFF Research Database (Denmark)

    Pemsel, Sofia; Wiewiorac, Anna; Müller, Ralf

    2014-01-01

    This paper conceptualizes and defines knowledge governance (KG) in project-based organizations (PBOs). Two key contributions towards a multi-faceted view of KG and an understanding of KG in PBOs are advanced, as distinguished from knowledge management and organizational learning concepts. The con......This paper conceptualizes and defines knowledge governance (KG) in project-based organizations (PBOs). Two key contributions towards a multi-faceted view of KG and an understanding of KG in PBOs are advanced, as distinguished from knowledge management and organizational learning concepts....... The conceptual framework addresses macro- and micro-level elements of KG and their interaction. Our definition of KG in PBOs highlights the contingent nature of KG processes in relation to their organizational context. These contributions provide a novel platform for understanding KG in PBOs....

  14. Deposition and characteristics of PbS thin films by an in-situ solution chemical reaction process

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Junna; Ji, Huiming; Wang, Jian; Zheng, Xuerong; Lai, Junyun; Liu, Weiyan; Li, Tongfei [School of Materials Science and Engineering, Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China); Ma, Yuanliang; Li, Haiqin; Zhao, Suqin [College of Physics and Electronic Information Engineering, Qinghai University for Nationalities, Xining 810007 (China); Jin, Zhengguo, E-mail: zhgjin@tju.edu.cn [School of Materials Science and Engineering, Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China)

    2015-09-01

    Preferential oriented and uniform PbS thin films were deposited by a room temperature in-situ solution chemical reaction process, in which the lead nitrate as precursor in a form of thin solid films from lead precursor solution was used to react with ammonium sulfide ethanol solution. Influence of 1-butanol addition in the lead precursor solution, Pb:S molar ratios in the separate cationic and anionic solutions, deposition cycle numbers and annealing treatment in Ar atmosphere on structure, morphology, chemical composition and optical absorption properties of the deposited PbS films were investigated based on X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectrometer, atomic force microscopy, selected area electron diffraction, UV–vis, near infrared ray and fourier transform infrared spectroscopy measurements. The results showed that the deposited PbS thin films had a cubic structure and highly preferred orientation along with the plane (100). The deposition rate of single-layer was stable, about 30 nm in thickness per deposition cycle. - Highlights: • Time-efficiency synthetic method for the preparation of lead sulfide (PbS) films • Effect of 1-butanol addition into cationic precursor solution is discussed. • Growth rate of the PbS films is stable at about 30 nm per cycle.

  15. Band-structure tailoring and surface passivation for highly efficient near-infrared responsive PbS quantum dot photovoltaics

    Science.gov (United States)

    Zhou, Ru; Niu, Haihong; Ji, Fengwei; Wan, Lei; Mao, Xiaoli; Guo, Huier; Xu, Jinzhang; Cao, Guozhong

    2016-11-01

    PbS is a promising light harvester for near-infrared (NIR) responsive quantum dot (QD) photovoltaics due to its narrow bulk band gap (0.41 eV) and large exciton Bohr radius (18 nm). However, the relatively low conduction band (CB) and high-density surface defects of PbS as two major drawbacks for its use in solar cells severely hamper the photovoltaic performance enhancement. In this work, a modified solution-based successive ionic layer adsorption and reaction (SILAR) utilizing mixed cationic precursors of Pb2+ and Cd2+ is explored, and such a scheme offers two benefits, band-structure tailoring and surface passivation. In-situ deposited CdS suppresses the excessive growth of PbS in the mesopores, thereby facilitating the favorable electron injection from PbS to TiO2 in view of the up-shifted CB level of QDs; the intimate interpenetration of two sulfides with each other leads to superior passivation of trap state defects on PbS, which suppresses the interfacial charge recombination. With the construction of photovoltaics based on such a hybrid (Pb,Cd)S/CdS configuration, impressive power conversion efficiency up to 4.08% has been reached, outperforming that of the conventional PbS/CdS pattern (2.95%). This work highlights the great importance of band-structure tailoring and surface passivation for constructing highly efficient PbS QD photovoltaics.

  16. Interdisciplinary project-based learning: technology for improving student cognition

    OpenAIRE

    Natalia Stozhko; Boris Bortnik; Ludmila Mironova; Albina Tchernysheva; Ekaterina Podshivalova

    2015-01-01

    The article studies a way of enhancing student cognition by using interdisciplinary project-based learning (IPBL) in a higher education institution. IPBL is a creative pedagogic approach allowing students of one area of specialisation to develop projects for students with different academic profiles. The application of this approach in the Ural State University of Economics resulted in a computer-assisted learning system (CALS) designed by IT students. The CALS was used in an analytical chemi...

  17. Project-Based Laboratory Experiences in Mechanical Engineering

    Directory of Open Access Journals (Sweden)

    Narendra Sharma

    2011-12-01

    Full Text Available In this paper we describe project-based laboratories in Mechanical Engineering designed to provide semester-long team experiences which mimic the real life industrial processes of design, development, testing and optimization. The labs are focused on courses at the sophomore level and thus require special attention to constraints of student backgrounds and experience. This paper describes laboratory projects in Dynamics and Fluid Mechanics.

  18. Understanding Project Based Production through Socio-technical Modularity

    DEFF Research Database (Denmark)

    Thuesen, Christian Langhoff

    This paper develops an approach for understanding Project Based Production. This form of production is characterized by unique deliverables, high complexity, high value, high risk, profound uncertainty and many stakeholders and is increasingly important the postmodern society. Common to the pract......This paper develops an approach for understanding Project Based Production. This form of production is characterized by unique deliverables, high complexity, high value, high risk, profound uncertainty and many stakeholders and is increasingly important the postmodern society. Common...... to the practices of PBP and other production practices is the goal of balancing the dilemma between creativity and productivity. In response to industrialized production, the concept of modularity gained popularity for addressing this dilemma by exploring product, process and organization structures. However...... with the starting point in system theory and a strong bias towards industrial production, the predominant understanding of modularity faces difficulty in explaining practices of Project Based Production in both social – technical and dynamic – stable aspects. Illustrated by a case the paper addresses this gap...

  19. Evaluation of project based learning sufficiency of teacher candidates

    Directory of Open Access Journals (Sweden)

    Vasfi Tugun

    2012-01-01

    Full Text Available The aim of that research, it is the project based learning process suffuciency of teacher candidates who developedmultimedia by working in online and blended groups. Importance of research Being able to guide to studies that is going tobe done about assessment of multimedia projection for project based educational application to teachers and teachercandidates and It has been thought as an advisor source about being arranged new educational environment for the futureto teacher and teacher candidates for project based educational application and multimedia projection. Research is anexperimental study and has been shaped according to pre-test and last-test research model with the two groups. This groupsare online group and blended group. Discussion of research In the result of the study, in the process of project basedlearning, it is determined that the success level in multimedia development of teacher candidates who work in blendedlearning model is higher than the success level of teacher candidates who work in online learning model.

  20. iPBS: a universal method for DNA fingerprinting and retrotransposon isolation.

    Science.gov (United States)

    Kalendar, Ruslan; Antonius, Kristiina; Smýkal, Petr; Schulman, Alan H

    2010-11-01

    Molecular markers are essential in plant and animal breeding and biodiversity applications, in human forensics, and for map-based cloning of genes. The long terminal repeat (LTR) retrotransposons are well suited as molecular markers. As dispersed and ubiquitous transposable elements, their "copy and paste" life cycle of replicative transposition leads to new genome insertions without excision of the original element. Both the overall structure of retrotransposons and the domains responsible for the various phases of their replication are highly conserved in all eukaryotes. Nevertheless, up to a year has been required to develop a retrotransposon marker system in a new species, involving cloning and sequencing steps as well as the development of custom primers. Here, we describe a novel PCR-based method useful both as a marker system in its own right and for the rapid isolation of retrotransposon termini and full-length elements, making it ideal for "orphan crops" and other species with underdeveloped marker systems. The method, iPBS amplification, is based on the virtually universal presence of a tRNA complement as a reverse transcriptase primer binding site (PBS) in LTR retrotransposons. The method differs from earlier retrotransposon isolation methods because it is applicable not only to endogenous retroviruses and retroviruses, but also to both Gypsy and Copia LTR retrotransposons, as well as to non-autonomous LARD and TRIM elements, throughout the plant kingdom and to animals. Furthermore, the inter-PBS amplification technique as such has proved to be a powerful DNA fingerprinting technology without the need for prior sequence knowledge.

  1. Entwicklung eines Summenparameters für potenziell bioakkumulierbare Stoffe (PBS) im Abwasser

    OpenAIRE

    Stenz, Georg

    2001-01-01

    Es wurde ein Summenparameter für potenziell bioakkumulierbare Stoffe (PBS) im Abwasser entwickelt. Der Summenparameter soll als Instrumentarium zur Überwachung von Einleitungen, Emissionen und Verlusten an anreicherungsfähigen Stoffen eingesetzt werden, da die Bioakkumulation besonders für marine Ökosysteme ein Gefährdungskriterium darstellt. Stoffe werden nach dem „Technical Guidance Document (TGD)“ als potenziell bioakkumulierbar bertrachtet, wenn deren log POW-Wert größer als drei ist. Der...

  2. South African performance based standards (PBS) vehicle to transport steel pipes

    CSIR Research Space (South Africa)

    Dessein, T

    2010-03-01

    Full Text Available measures the vehicle?s rollover stability. Rearward Amplification (RA) ? Measures the degree to which the lateral accelerations experienced by trailing units are amplified in comparison to that of the towing unit in a high speed evasive single lane...-speed 90? turn high-speed travel along a 1.0km long straight road with uneven road surface a pulse-steer test HVTT11: A South African PBS Vehicle to Transport Pipes 10 a constant radius turn at slowly increasing speed an evasive lane change...

  3. Genetic analysis of the genus Diospyros ssp. using RAPD and i-PBS methods

    Directory of Open Access Journals (Sweden)

    Jana Raddová

    2012-01-01

    Full Text Available Molecular techniques (RAPD and i-PBS were used to study genetic diversity within persimmon collection at Horticulture Faculty of Mendel University in Lednice. The aim of the work was to distinguish 14 known and 6 of unknown origin persimmon cultivars. The basic screening of 20 OPT primers was applied to 4 cultivars differring in the place of origin. Within the group of screened primers there were chosen those, which gave polymorphic repeatable strong and middle strong bands. Selected primers were used for the RAPD reactions within the whole persimmon collection. Three OPA primers previously described in the literature were also used for the RAPD reactions within the whole persimmon collection. Additional 16 i-PBS primers previously described in the literature were also used for i-PBS analysis of the whole group of cultivars. Amplification was successful with 12 i-PBS primers. The FreeTree software package was used to gen­erate a similarity matrix and then to produce a dendrogram using UPGMA analyses. The similarity dendrograms of all persimmon cultivars were created based on both approaches and also on combination of both analyses by program Tree View. All the dendrograms clearly separated the assessed cultivars into 4 clusters. There are cluster of American persimmons – Meader’ (1, ’Garretson’ (2 and ’Early Golden’ (3. They are representatives of D. virginiana. Further part of dendrogram includes single D. lotus (5, which is also clearly separated from other cultivars of the genus Diospyros. The third cluster includes interspecific hybrids ’Rossiyanka’ (10 and ’Nikitskaiya Bordovaiya’ (13, which arised from crosses of D. virginiana and D. kaki. The last cluster is formed by cultivars of Japanese persimmon – ’Mikatani Gosho’, ’Zenjimaru’, ’Tone Wase’, ’Hiratanenashi’, ’Fuyu’, Chinese cultivar – ’Sansi’ and two Italian cultivars ’Vaniglia’ and ’Tipo’. They are clustered without significant

  4. Photoluminescence under high-electric field of PbS quantum dots

    Directory of Open Access Journals (Sweden)

    B. Ullrich

    2012-12-01

    Full Text Available The effect of a laterally applied electric field (≤10 kV/cm on the photoluminescence of colloidal PbS quantum dots (diameter of 2.7 nm on glass was studied. The field provoked a blueshift of the emission peak, a reduction of the luminescent intensity, and caused an increase in the full width at half maximum of the emission spectrum. Upon comparison with the photoluminescence of p-type GaAs exhibits the uniqueness of quantum dot based electric emission control with respect to bulk materials.

  5. Corrosion of experimental magnesium alloys in blood and PBS: A gravimetric and microscopic evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Schille, Ch., E-mail: Christine.Schille@med.uni-tuebingen.de [University Hospital Tuebingen, Center for Dentistry, Oral Medicine and Maxillofacial Surgery, Section Medical Materials and Technology, Osianderstr. 2-8, D-72076 Tuebingen (Germany); Braun, M.; Wendel, H.P. [University Hospital Tuebingen, Div. Congenital and Paediatric Cardiac Surgery, University Children' s Hospital, Tuebingen, Germany, Calwerstr. 7/1, D-72076 Tuebingen (Germany); Scheideler, L. [University Hospital Tuebingen, Center for Dentistry, Oral Medicine and Maxillofacial Surgery, Section Medical Materials and Technology, Osianderstr. 2-8, D-72076 Tuebingen (Germany); Hort, N. [GKSS Research Centre, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Reichel, H.-P. [Weissensee Company, Buergermeister-Ebert-Str. 30-32, D-36124 Eichenzell (Germany); Schweizer, E.; Geis-Gerstorfer, J. [University Hospital Tuebingen, Center for Dentistry, Oral Medicine and Maxillofacial Surgery, Section Medical Materials and Technology, Osianderstr. 2-8, D-72076 Tuebingen (Germany)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Corrosion of eight Mg-based Biomaterials was tested in saline and human blood. Black-Right-Pointing-Pointer Corrosion behaviour in physiological saline and in blood was entirely different. Black-Right-Pointing-Pointer Al and Zn had the highest influence on corrosion behaviour in both electrolytes. Black-Right-Pointing-Pointer MgAl9 and MgAl9Zn1 showed least corrosion in human whole blood. Black-Right-Pointing-Pointer Tests in buffered corrosion media are not sufficient to predict corrosion in vivo. - Abstract: Corrosion tests for medical materials are often performed in simulated body fluids (SBF). When SBF are used for corrosion measurement, the open question is, how well they match the conditions in the human body. The aim of the study was to compare the corrosion behaviour of different experimental magnesium alloys in human whole blood and PBS{sup minus} (phosphate buffered saline w/o Ca and Mg) as a simulated body fluid by gravimetric weight measurements and microscopic evaluation. Eight different experimental magnesium alloys, containing neither Mn nor other additives, were manufactured. With these alloys, a static immersion test in PBS{sup minus} and a dynamic test using the Chandler-loop model with human whole blood over 6 h were performed. During the static immersion test, the samples were weighed every hour. During the dynamic test, the specimens were weighed before and after the 6 h incubation period in the Chandler-loop. From both tests, the total mass change was calculated for each alloy and the values were compared. Additionally, microscopic pictures from the samples were taken at the end of the test period. All alloys showed different corrosion behaviour in both tests, especially the alloys with high aluminium content, MgAl9 and MgAl9Zn1. Generally, alloys in PBS showed a weight gain due to generation of a microscopically visible corrosion layer, while in the blood test system a more or less distinct weight

  6. Corrosion of experimental magnesium alloys in blood and PBS: A gravimetric and microscopic evaluation

    International Nuclear Information System (INIS)

    Schille, Ch.; Braun, M.; Wendel, H.P.; Scheideler, L.; Hort, N.; Reichel, H.-P.; Schweizer, E.; Geis-Gerstorfer, J.

    2011-01-01

    Highlights: ► Corrosion of eight Mg–based Biomaterials was tested in saline and human blood. ► Corrosion behaviour in physiological saline and in blood was entirely different. ► Al and Zn had the highest influence on corrosion behaviour in both electrolytes. ► MgAl9 and MgAl9Zn1 showed least corrosion in human whole blood. ► Tests in buffered corrosion media are not sufficient to predict corrosion in vivo. - Abstract: Corrosion tests for medical materials are often performed in simulated body fluids (SBF). When SBF are used for corrosion measurement, the open question is, how well they match the conditions in the human body. The aim of the study was to compare the corrosion behaviour of different experimental magnesium alloys in human whole blood and PBS minus (phosphate buffered saline w/o Ca and Mg) as a simulated body fluid by gravimetric weight measurements and microscopic evaluation. Eight different experimental magnesium alloys, containing neither Mn nor other additives, were manufactured. With these alloys, a static immersion test in PBS minus and a dynamic test using the Chandler-loop model with human whole blood over 6 h were performed. During the static immersion test, the samples were weighed every hour. During the dynamic test, the specimens were weighed before and after the 6 h incubation period in the Chandler-loop. From both tests, the total mass change was calculated for each alloy and the values were compared. Additionally, microscopic pictures from the samples were taken at the end of the test period. All alloys showed different corrosion behaviour in both tests, especially the alloys with high aluminium content, MgAl9 and MgAl9Zn1. Generally, alloys in PBS showed a weight gain due to generation of a microscopically visible corrosion layer, while in the blood test system a more or less distinct weight loss was observed. When alloys are ranked according to corrosion susceptibility, the results differ also between the test systems. The

  7. Formation of superlattice with aligned plane orientation of colloidal PbS quantum dots

    Science.gov (United States)

    Mukai, Kohki; Fujimoto, Satoshi; Suetsugu, Fumimasa

    2018-04-01

    We investigated a method of forming a perfect quantum dot (QD) superlattice, in which each QD has the same plane orientation, by depositing colloidal PbS QDs with clear facets in solution. QD facets were controlled by adjusting the synthesis temperature. X-ray evaluation showed that the crystal orientations of the film with QDs having clear facets were aligned. The slow deposition promoted this crystal alignment. The red shift of photoluminescence wavelength caused by the film formation was larger with QDs having facets than with spherical QDs, suggesting that the connection of the wave function between QDs was better so that the quantum size effect was further reduced.

  8. 2 W high efficiency PbS mid-infrared surface emitting laser

    Science.gov (United States)

    Ishida, A.; Sugiyama, Y.; Isaji, Y.; Kodama, K.; Takano, Y.; Sakata, H.; Rahim, M.; Khiar, A.; Fill, M.; Felder, F.; Zogg, H.

    2011-09-01

    High efficiency laser operation with output power exceeding 2 W was obtained for vertical external-cavity PbS based IV-VI compound surface emitting quantum-well structures. The laser showed external quantum efficiency as high as 16%. Generally, mid-infrared III-V or II-VI semiconductor laser operation utilizing interband electron transitions are restricted by Auger recombination and free carrier absorption. Auger recombination is much lower in the IV-VI semiconductors, and the free-carrier absorption is significantly reduced by an optically pumped laser structure including multi-step optical excitation layers.

  9. Co-sensitization of quantum dot sensitized solar cells composed of TiO2 nanocrystalline photoanode with CdS and PbS nanoparticles and effect of PbS on the performance of solar cell

    Directory of Open Access Journals (Sweden)

    Maziar Marandi

    2017-09-01

    Full Text Available In this research, CdS and PbS quantum dots were applied as the light sensitizers in TiO2 based nanostructured solar cells. The PbS quantum dots could absorb a wide range of the sunlight spectrum on earth due to their low bandgap energy. As a result, the cell sensitization is more effective by application of both CdS and PbS quantum dots sensitizers. The TiO2 nanocrystals were synthesized through a hydrothermal process and deposited on FTO glass substrates as the photoanode scaffold. Then PbS quantum dots were grown on the surface of this nanocrystalline layer by a successive ionic layer adsorption and reaction (SILAR method. The CdS quantum dots were over-grown in the next step through a similar deposition method. Finally this sensitized layer was applied as the photoelectrode of the corresponding quantum dot sensitized solar cells. The results demonstrated that the maximum efficiency was achieved for the cell with a photoanode made of co-sensitization through 2 and 6 cycles of PbS and CdS deposition, respectively. The photovoltaic parameters of this cell were measured as Jsc of 10.81 mA/cm2, Voc of 590 mv and energy conversion efficiency of 2.7+0.2%.

  10. Enhanced Mobility-Lifetime Products in PbS Colloidal Quantum Dot Photovoltaics

    KAUST Repository

    Jeong, Kwang S.

    2012-01-24

    Figure Persented: Colloidal quantum dot (CQD) photovoltaics offer a promising approach to harvest the near-IR region of the solar spectrum, where half of the sun\\'s power reaching the earth resides. High external quantum efficiencies have been obtained in the visible region in lead chalcogenide CQD photovoltaics. However, the corresponding efficiencies for band gap radiation in the near-infrared lag behind because the thickness of CQD photovoltaic layers from which charge carriers can be extracted is limited by short carrier diffusion lengths. Here, we investigate, using a combination of electrical and optical characterization techniques, ligand passivation strategies aimed at tuning the density and energetic distribution of charge trap states at PbS nanocrystal surfaces. Electrical and optical measurements reveal a more than 7-fold enhancement of the mobility-lifetime product of PbS CQD films treated with 3-mercaptopropionic acid (MPA) in comparison to traditional organic passivation strategies that have been examined in the literature. We show by direct head-to-head comparison that the greater mobility-lifetime products of MPA-treated devices enable markedly greater short-circuit current and higher power conversion efficiency under AM1.5 illumination. Our findings highlight the importance of selecting ligand treatment strategies capable of passivating a diversity of surface states to enable shallower and lower density trap distributions for better transport and more efficient CQD solar cells. © 2011 American Chemical Society.

  11. Size-dependent optical properties of colloidal PbS quantum dots.

    Science.gov (United States)

    Moreels, Iwan; Lambert, Karel; Smeets, Dries; De Muynck, David; Nollet, Tom; Martins, José C; Vanhaecke, Frank; Vantomme, André; Delerue, Christophe; Allan, Guy; Hens, Zeger

    2009-10-27

    We quantitatively investigate the size-dependent optical properties of colloidal PbS nanocrystals or quantum dots (Qdots), by combining the Qdot absorbance spectra with detailed elemental analysis of the Qdot suspensions. At high energies, the molar extinction coefficient epsilon increases with the Qdot volume d(3) and agrees with theoretical calculations using the Maxwell-Garnett effective medium theory and bulk values for the Qdot dielectric function. This demonstrates that quantum confinement has no influence on epsilon in this spectral range, and it provides an accurate method to calculate the Qdot concentration. Around the band gap, epsilon only increases with d(1.3), and values are comparable to the epsilon of PbSe Qdots. The data are related to the oscillator strength f(if) of the band gap transition and results agree well with theoretical tight-binding calculations, predicting a linear dependence of f(if) on d. For both PbS and PbSe Qdots, the exciton lifetime tau is calculated from f(if). We find values ranging between 1 and 3 mus, in agreement with experimental literature data from time-resolved luminescence spectroscopy. Our results provide a thorough general framework to calculate and understand the optical properties of suspended colloidal quantum dots. Most importantly, it highlights the significance of the local field factor in these systems.

  12. Sourcing Team Behavior in Project-Based MNE's

    DEFF Research Database (Denmark)

    Hansen, Anders Peder Lysholm

    2014-01-01

    across the three cases was characterized by conflict between departments represented in the category teams. This resulted in unfortunate sourcing team behaviour and unaligned performance management, which in turn had a number of adverse effects. Further research on how to create a holistic and balanced......This paper presents and discusses a multiple case study of three cross-functional category teams responsible for sourcing critical components within multi-national, project-based enterprises. The study focused on behaviour and management of the sourcing teams and found that the sourcing process...... team perspective in the sourcing teams is suggested....

  13. Knowledge Governance Strategies in Project-based Organizations

    DEFF Research Database (Denmark)

    Pemsel, Sofia; Müller, Ralf; Söderlund, Jonas

    2016-01-01

    Knowledge governance (KG) aims at strategically influencing knowledge processes by implementing governance mechanisms. Little is known about whether, how, or why such strategies differ among firms. We utilize a large-scale empirical study of 20 organizations to develop a typology of KG strategies...... in project-based organizations; we then explore how these strategies emerge and affect organizational knowledge processes. Six strategies are identified: Protector, Deliverer, Polisher, Explorer, Supporter, and Analyzer. This paper posits a multi-level categorization model to facilitate comparisons among KG...... strategies. We uncover three main drivers of organizations' chosen knowledge governance strategies-namely, attitudes about humans, knowledge, and knowledge control....

  14. Process competencies in a problem and project based learning environment

    DEFF Research Database (Denmark)

    Du, Xiangyun; Kolmos, Anette

    2006-01-01

    with the expected professional competencies. Based on the educational practice of PBL Aalborg Model, which is characterized by problem-orientation, project-organization and team work, this paper examines the process of developing process competencies through studying engineering in a PBL environment from...... process competencies through doing problem and project based work in teams? 2) How do students perceive their achievement of these process competencies?......Future engineers are not only required to master technological competencies concerning solving problems, producing and innovating technology, they are also expected to have capabilities of cooperation, communication, and project management in diverse social context, which are referred to as process...

  15. In-service teachers' perceptions of project-based learning.

    Science.gov (United States)

    Habók, Anita; Nagy, Judit

    2016-01-01

    The study analyses teachers' perceptions of methods, teacher roles, success and evaluation in PBL and traditional classroom instruction. The analysis is based on empirical data collected in primary schools and vocational secondary schools. An analysis of 109 questionnaires revealed numerous differences based on degree of experience and type of school. In general, project-based methods were preferred among teachers, who mostly perceived themselves as facilitators and considered motivation and transmission of values central to their work. Teachers appeared not to capitalize on the use of ICT tools or emotions. Students actively participated in the evaluation process via oral evaluation.

  16. Preparation of nanostructured PbS thin films as sensing element for NO{sub 2} gas

    Energy Technology Data Exchange (ETDEWEB)

    Kaci, S., E-mail: k_samira05@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE) Division Couches Minces et Interfaces, 02 Bd Frantz Fanon, B.P. 140, 7 Merveilles, 16038 Algiers (Algeria); Keffous, A.; Hakoum, S. [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE) Division Couches Minces et Interfaces, 02 Bd Frantz Fanon, B.P. 140, 7 Merveilles, 16038 Algiers (Algeria); Trari, M. [Université des Sciences et Technologies Houari Boumediene (USTHB), Laboratoire de Stockage et de Valorisation des Eneriges Renouvelables, Faculté de Chimie, BP 32, EL Alia, 16111 Bab Ezzouar, Algiers (Algeria); Mansri, O.; Menari, H. [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE) Division Couches Minces et Interfaces, 02 Bd Frantz Fanon, B.P. 140, 7 Merveilles, 16038 Algiers (Algeria)

    2014-06-01

    In this work, we demonstrate that semiconducting films of A{sub IV}B{sub VI} compounds, in particular, of nanostructured lead sulfide (PbS) which prepared by chemical bath deposition (CBD), can be used as a sensing element for nitrogen dioxide (NO{sub 2}) gas. The CBD method is versatile, simple in implementation and gives homogeneous semiconductor structures. We have prepared PbS nanocrystalline thin film at different reaction baths and temperatures. In the course of deposition, variable amounts of additives, such as organic substances among them, were introduced into the baths. The energy dispersive analysis (EDX) confirms the chemical composition of PbS films. A current–voltage (I–V) characterization of Pd/nc-PbS/a-SiC:H pSi(100)/Al Schottky diode structures were studied in the presence of NO{sub 2} gas. The gas sensing behavior showed that the synthesized PbS nanocrystalline thin films were influenced by NO{sub 2} gas at room temperature. The results can be used for developing an experimental sensing element based on chemically deposited nanostructured PbS films which can be applicable in gas sensors.

  17. Students’ Lived Experience of Project-Based Learning

    Directory of Open Access Journals (Sweden)

    Sandy Ferianda

    2017-07-01

    Full Text Available Inspired by personal experiences during the study time in the Graduate Program in English Language Studies (ELS Sanata Dharma University Yogyakarta, this research focused mainly on investigating the ELS students’ lived experience of project-based learning implemented by the ELS lecturers. This study employed hermeneutic phenomenology since it described and interpreted the meanings of ELS students lived experience. The participants of this study were the three ELS students considered to be illuminating from the three different streams batch of 2015. In this study we used one-on-one in depth interview to gain the data. The findings of this study consisted of four prefigured meanings and two emergent meanings namely a authentic learning, b learner autonomy, c cooperative learning, d multiple intelligences, e understanding others, and f personal development. The findings of this study gave implications not only to the ELS students and lecturers, but also to the audience. Lastly, recommendations were also addressed to the ELS students as their habit formation, to the ELS lecturers as their inputs to give more feedbacks to their students, and to the future researchers. Keywords: Lived experience, project-based learning.

  18. Teaching physics using project-based engineering curriculum with a theme of alternative energy

    Science.gov (United States)

    Tasior, Bryan

    The Next Generation Science Standards (NGSS) provide a new set of science standards that, if adopted, shift the focus from content knowledge-based to skill-based education. Students will be expected to use science to investigate the natural world and solve problems using the engineering design process. The world also is facing an impending crisis related to climate, energy supply and use, and alternative energy development. Education has an opportunity to help provide the much needed paradigm shift from our current methods of providing the energy needs of society. The purpose of this research was to measure the effectiveness of a unit that accomplishes the following objectives: uses project-based learning to teach the engineering process and standards of the NGSS, addresses required content expectations of energy and electricity from the HSCE's, and provides students with scientific evidence behind issues (both environmental and social/economic) relating to the energy crisis and current dependence of fossil fuels as our primary energy source. The results of the research indicate that a physics unit can be designed to accomplish these objectives. The unit that was designed, implemented and reported here also shows that it was highly effective at improving students' science content knowledge, implementing the engineering design standards of the NGSS, while raising awareness, knowledge and motivations relating to climate and the energy crisis.

  19. Electrochemical surface-enhanced Raman scattering measurement on ligand capped PbS quantum dots at gap of Au nanodimer

    Science.gov (United States)

    Li, Xiaowei; Minamimoto, Hiro; Murakoshi, Kei

    2018-05-01

    The vibrational characteristics of ligand-capped lead sulfide (PbS) quantum dots (QDs) were clarified via electrochemical surface-enhanced Raman spectroscopy (EC-SERS) using a hybridized system of gold (Au) nanodimers and PbS QDs under electrochemical potential control. Enhanced electromagnetic field caused by the coupling of QDs with plasmonic Au nanodimers allowed the characteristic behavior of the ligand oleic acid (OA) on the PbS QD surface to be detected under electrochemical potential control. Binding modes between the QDs and OA molecules were characterized using synchronous two-dimensional correlation spectra at distinct electrochemical potentials, confirming that the bidentate bridging mode was probably the most stable mode even under relatively negative potential polarization. Changes in binding modes and molecular orientations resulted in fluctuations in EC-SERS spectra. The present observations strongly recommend the validity of the QD-plasmonic nanostructure coupled system for sensitive molecular detection via EC-SERS.

  20. The Effect of Substrate Temperature on the Structural Properties of Spray Pyrolysed Lead Sulphide (PbS Thin Films

    Directory of Open Access Journals (Sweden)

    Mohammad G. Faraj

    2014-09-01

    Full Text Available Lead sulphide (PbS films were prepared by the chemical spray pyrolysis technique using a solution of Lead nitrate and thiourea. PbS films were deposited (prepared on glass substrate at varied temperature (250-350 oC. Effects of substrate temperature on the structural characteristics of the films were studied. The X-ray diffraction patterns’ results reveal that the all of PbS films have a face centered cubic structure. The X-ray diffraction study showed that irrespective of substrate temperature all the films exhibits a preferred orientation along the (200 plane. The degree of preferred orientation increased with the substrate temperature. It was observed that the increase of the substrate temperature increase the diffraction peak intensity of (200 plane which resulted in increase in grain size and good crystallinity of the films.

  1. Effects of Hydroxylation on PbS Quantum Dot Sensitized TiO2 Nanotube Array Photoelectrodes

    International Nuclear Information System (INIS)

    Liu, Zhongqing; Wang, Bin; Wu, Jianchun; Dong, Qiang; Zhang, Xiaoming; Xu, He

    2016-01-01

    ABSTRACT: The contact state at the heterojunction interfaces greatly influences the interfacial kinetics of the photoinduced charge carriers. In this study, we used a facile NaOH pretreatment to replenish the hydroxyl groups lost during the heat treatment for crystallization of TiO 2 nanotube arrays (TNAs) prepared via anodic oxidization. By reacting the carboxylic acid groups of thioglycolic acid (TGA) with the TiO 2 surface hydroxyl groups, TGA molecules were covalently linked to the TiO 2 surface and then PbS quantum dots (QDs) were anchored onto the TNAs via the successive ionic layer adsorption and reaction (SILAR) method. The sample microstructure and photoelectrochemical properties were analyzed with X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM),current–voltage characteristics (J–V), electrochemical impedance spectroscopy (EIS), transient photovoltage plots and Mott-Schottky curves. The contact state and electrostatic potential distribution between TiO 2 {1 0 1} and PbS {1 1 1} planes were estimated by using first principle simulation. It was found that the NaOH pretreatment could enhance the crystallization degree of PbS QDs, decrease the crystal face mismatch, dangling bond density and the interfacial resistance between PbS QDs and TiO 2 , and accelerate the interfacial separation and transfer of photoinduced charge carriers. The first principle calculations demonstrated that the PbS QDs and TiO 2 interfacial contact was strengthened, and the built-in electric field was induced from TiO 2 {1 0 1} towards PbS {1 1 1}. These combined effects apparently improved the device photoelectrochemical performance. Compared to the sample without pretreatment, the specimen pretreated with NaOH demonstrated 19.96% and 29.93% increases in peak photoconversion efficiency after five and ten cycles of SILAR deposition, respectively.

  2. WE-E-BRB-03: Implementation of PBS Proton Therapy Treatment for Free Breathing Lung Cancer Patients

    International Nuclear Information System (INIS)

    Li, H.

    2016-01-01

    Strategies for treating thoracic and liver tumors using pencil beam scanning proton therapy Thoracic and liver tumors have not been treated with pencil beam scanning (PBS) proton therapy until recently. This is because of concerns about the significant interplay effects between proton spot scanning and patient’s respiratory motion. However, not all tumors have unacceptable magnitude of motion for PBS proton therapy. Therefore it is important to analyze the motion and understand the significance of the interplay effect for each patient. The factors that affect interplay effect and its washout include magnitude of motion, spot size, spot scanning sequence and speed. Selection of beam angle, scanning direction, repainting and fractionation can all reduce the interplay effect. An overview of respiratory motion management in PBS proton therapy including assessment of tumor motion and WET evaluation will be first presented. As thoracic tumors have very different motion patterns from liver tumors, examples would be provided for both anatomic sites. As thoracic tumors are typically located within highly heterogeneous environments, dose calculation accuracy is a concern for both treatment target and surrounding organs such as spinal cord or esophagus. Strategies for mitigating the interplay effect in PBS will be presented and the pros and cons of various motion mitigation strategies will be discussed. Learning Objectives: Motion analysis for individual patients with respect to interplay effect Interplay effect and mitigation strategies for treating thoracic/liver tumors with PBS Treatment planning margins for PBS The impact of proton dose calculation engines over heterogeneous treatment target and surrounding organs I have a current research funding from Varian Medical System under the master agreement between University of Pennsylvania and Varian; L. Lin, I have a current funding from Varian Medical System under the master agreement between University of Pennsylvania and

  3. WE-E-BRB-02: Implementation of Pencil Beam Scanning (PBS) Proton Therapy Treatment for Liver Patient

    International Nuclear Information System (INIS)

    Lin, L.

    2016-01-01

    Strategies for treating thoracic and liver tumors using pencil beam scanning proton therapy Thoracic and liver tumors have not been treated with pencil beam scanning (PBS) proton therapy until recently. This is because of concerns about the significant interplay effects between proton spot scanning and patient’s respiratory motion. However, not all tumors have unacceptable magnitude of motion for PBS proton therapy. Therefore it is important to analyze the motion and understand the significance of the interplay effect for each patient. The factors that affect interplay effect and its washout include magnitude of motion, spot size, spot scanning sequence and speed. Selection of beam angle, scanning direction, repainting and fractionation can all reduce the interplay effect. An overview of respiratory motion management in PBS proton therapy including assessment of tumor motion and WET evaluation will be first presented. As thoracic tumors have very different motion patterns from liver tumors, examples would be provided for both anatomic sites. As thoracic tumors are typically located within highly heterogeneous environments, dose calculation accuracy is a concern for both treatment target and surrounding organs such as spinal cord or esophagus. Strategies for mitigating the interplay effect in PBS will be presented and the pros and cons of various motion mitigation strategies will be discussed. Learning Objectives: Motion analysis for individual patients with respect to interplay effect Interplay effect and mitigation strategies for treating thoracic/liver tumors with PBS Treatment planning margins for PBS The impact of proton dose calculation engines over heterogeneous treatment target and surrounding organs I have a current research funding from Varian Medical System under the master agreement between University of Pennsylvania and Varian; L. Lin, I have a current funding from Varian Medical System under the master agreement between University of Pennsylvania and

  4. WE-E-BRB-03: Implementation of PBS Proton Therapy Treatment for Free Breathing Lung Cancer Patients

    Energy Technology Data Exchange (ETDEWEB)

    Li, H. [UT MD Anderson Cancer Center (United States)

    2016-06-15

    Strategies for treating thoracic and liver tumors using pencil beam scanning proton therapy Thoracic and liver tumors have not been treated with pencil beam scanning (PBS) proton therapy until recently. This is because of concerns about the significant interplay effects between proton spot scanning and patient’s respiratory motion. However, not all tumors have unacceptable magnitude of motion for PBS proton therapy. Therefore it is important to analyze the motion and understand the significance of the interplay effect for each patient. The factors that affect interplay effect and its washout include magnitude of motion, spot size, spot scanning sequence and speed. Selection of beam angle, scanning direction, repainting and fractionation can all reduce the interplay effect. An overview of respiratory motion management in PBS proton therapy including assessment of tumor motion and WET evaluation will be first presented. As thoracic tumors have very different motion patterns from liver tumors, examples would be provided for both anatomic sites. As thoracic tumors are typically located within highly heterogeneous environments, dose calculation accuracy is a concern for both treatment target and surrounding organs such as spinal cord or esophagus. Strategies for mitigating the interplay effect in PBS will be presented and the pros and cons of various motion mitigation strategies will be discussed. Learning Objectives: Motion analysis for individual patients with respect to interplay effect Interplay effect and mitigation strategies for treating thoracic/liver tumors with PBS Treatment planning margins for PBS The impact of proton dose calculation engines over heterogeneous treatment target and surrounding organs I have a current research funding from Varian Medical System under the master agreement between University of Pennsylvania and Varian; L. Lin, I have a current funding from Varian Medical System under the master agreement between University of Pennsylvania and

  5. WE-E-BRB-02: Implementation of Pencil Beam Scanning (PBS) Proton Therapy Treatment for Liver Patient

    Energy Technology Data Exchange (ETDEWEB)

    Lin, L. [University of Pennsylvania (United States)

    2016-06-15

    Strategies for treating thoracic and liver tumors using pencil beam scanning proton therapy Thoracic and liver tumors have not been treated with pencil beam scanning (PBS) proton therapy until recently. This is because of concerns about the significant interplay effects between proton spot scanning and patient’s respiratory motion. However, not all tumors have unacceptable magnitude of motion for PBS proton therapy. Therefore it is important to analyze the motion and understand the significance of the interplay effect for each patient. The factors that affect interplay effect and its washout include magnitude of motion, spot size, spot scanning sequence and speed. Selection of beam angle, scanning direction, repainting and fractionation can all reduce the interplay effect. An overview of respiratory motion management in PBS proton therapy including assessment of tumor motion and WET evaluation will be first presented. As thoracic tumors have very different motion patterns from liver tumors, examples would be provided for both anatomic sites. As thoracic tumors are typically located within highly heterogeneous environments, dose calculation accuracy is a concern for both treatment target and surrounding organs such as spinal cord or esophagus. Strategies for mitigating the interplay effect in PBS will be presented and the pros and cons of various motion mitigation strategies will be discussed. Learning Objectives: Motion analysis for individual patients with respect to interplay effect Interplay effect and mitigation strategies for treating thoracic/liver tumors with PBS Treatment planning margins for PBS The impact of proton dose calculation engines over heterogeneous treatment target and surrounding organs I have a current research funding from Varian Medical System under the master agreement between University of Pennsylvania and Varian; L. Lin, I have a current funding from Varian Medical System under the master agreement between University of Pennsylvania and

  6. A novel polarization demodulation method using polarization beam splitter (PBS) for dynamic pressure sensor

    Science.gov (United States)

    Su, Yang; Zhou, Hua; Wang, Yiming; Shen, Huiping

    2018-03-01

    In this paper we propose a new design to demodulate polarization properties induced by pressure using a PBS (polarization beam splitter), which is different with traditional polarimeter based on the 4-detector polarization measurement approach. The theoretical model is established by Muller matrix method. Experimental results confirm the validity of our analysis. Proportional relationships and linear fit are found between output signal and applied pressure. A maximum sensitivity of 0.092182 mv/mv is experimentally achieved and the frequency response exhibits a <0.14 dB variation across the measurement bandwidth. The sensitivity dependence on incident SOP (state of polarization) is investigated. The simple and all-fiber configuration, low-cost and high speed potential make it promising for fiber-based dynamic pressure sensing.

  7. Noncovalent Attachment of PbS Quantum Dots to Single- and Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Anirban Das

    2014-01-01

    Full Text Available Attachment of PbS quantum dots (QD to single-walled carbon nanotubes (SWNT and multiwalled carbon nanotubes (MWCNT is described; wherein commercially obtained PbS-QD of size 2.7 nm, stabilized by oleic acid, are added to a suspension of single- or multiwalled carbon nanotubes (CNT prefunctionalized noncovalently with 1,2-benzenedimethanethiol (1,2-BDMT in ethanol. The aromatic part of 1,2-BDMT attaches to the CNT by π-π stacking interactions, noncovalently functionalizing the CNT. The thiol part of the 1,2-BDMT on the functionalized CNT replaces oleic acid on the surface of the QD facilitating the noncovalent attachment of the QD to the CNT. The composites were characterized by TEM and FTIR spectroscopy. Quenching of NIR fluorescence of the PbS-QD on attachment to the carbon nanotubes (CNT was observed, indicating FRET from the QD to the CNT.

  8. EFEKTIVITAS PROJECT BASED LEARNING TERHADAP KETERAMPILAN MENULIS BAHAN AJAR IPA CALON GURU SD

    Directory of Open Access Journals (Sweden)

    - Susilawati

    2018-01-01

    Full Text Available Abstract:. The purpose of this research is to analyze the effectiveness of Project Based Learning (PjBL of writing skills on Science teaching materials to elementary school teachers candidates.This research used experimental methods (single-one group pretest-posttest design with instruments such as portofolio assessment sheets, observation sheets, and  questionnaire sheets .The effectiveness of analyzing used n-gain and t-test .The subject of this research is elementary school teachers candidates who contracted “Science Learning”subject  in a program study teacher education of elementary school at University Muhammadiyah Cirebon. The findings of this study has produced a contextual book for Science teaching material. In addition, there is an increased of elementary school teachers candidates who prepared the teaching materials in a printed form relevant to the needs and characters of the students as well as the curriculum. It is proven by assessments that the ability rose significantly from 2,71 (category  is adequate skill to 3,83 (category is skilled and supported by the n-gain value  at 0,87. Based on the t-test count of 8,050 larger than t-table 2,045. Recommendations from this research is that PjBL as a learning model could become one of the alternative learning models to improve writing skills material for elementary school teachers candidates. Keyword: Project-Based-Learning, science-materials-teaching, elementary-schoo-teachers- candidates.   Abstrak: Tujuan penelitian ini untuk menganalisis efektivitas Project Based Learning (PjBL terhadap keterampilan menulis bahan ajar IPA Calon Guru SD. Penelitian ini menggunakan metode eksperimen (Single-One Group Pretest-Posttest Design dengan menggunakan instrumen berupa lembar penilaian portofolio, lembar observasi, dan lembar angket. Efektivitas dianalisis menggunakan n-gain dan uji T. Subjek penelitian ini adalah mahasiswa calon guru yang mengontrak matakuliah Pembelajaran IPA di

  9. A study of lateral fall-off (penumbra) optimisation for pencil beam scanning (PBS) proton therapy

    Science.gov (United States)

    Winterhalter, C.; Lomax, A.; Oxley, D.; Weber, D. C.; Safai, S.

    2018-01-01

    The lateral fall-off is crucial for sparing organs at risk in proton therapy. It is therefore of high importance to minimize the penumbra for pencil beam scanning (PBS). Three optimisation approaches are investigated: edge-collimated uniformly weighted spots (collimation), pencil beam optimisation of uncollimated pencil beams (edge-enhancement) and the optimisation of edge collimated pencil beams (collimated edge-enhancement). To deliver energies below 70 MeV, these strategies are evaluated in combination with the following pre-absorber methods: field specific fixed thickness pre-absorption (fixed), range specific, fixed thickness pre-absorption (automatic) and range specific, variable thickness pre-absorption (variable). All techniques are evaluated by Monte Carlo simulated square fields in a water tank. For a typical air gap of 10 cm, without pre-absorber collimation reduces the penumbra only for water equivalent ranges between 4-11 cm by up to 2.2 mm. The sharpest lateral fall-off is achieved through collimated edge-enhancement, which lowers the penumbra down to 2.8 mm. When using a pre-absorber, the sharpest fall-offs are obtained when combining collimated edge-enhancement with a variable pre-absorber. For edge-enhancement and large air gaps, it is crucial to minimize the amount of material in the beam. For small air gaps however, the superior phase space of higher energetic beams can be employed when more material is used. In conclusion, collimated edge-enhancement combined with the variable pre-absorber is the recommended setting to minimize the lateral penumbra for PBS. Without collimator, it would be favourable to use a variable pre-absorber for large air gaps and an automatic pre-absorber for small air gaps.

  10. Colloidal PbS nanocrystals integrated to Si-based photonics for applications at telecom wavelengths

    Science.gov (United States)

    Humer, M.; Guider, R.; Jantsch, W.; Fromherz, T.

    2013-05-01

    In the last decade, Si based photonics has made major advances in terms of design, fabrication, and device implementation. But due to Silicon's indirect bandgap, it still remains a challenge to create efficient Si-based light emitting devices. In order to overcome this problem, an approach is to develop hybrid systems integrating light-emitting materials into Si. A promising class of materials for this purpose is the class of semiconducting nanocrystal quantum dots (NCs) that are synthesized by colloidal chemistry. As their absorption and emission wavelength depends on the dot size, which can easily be controlled during synthesis, they are extremely attractive as building blocks for nanophotonic applications. For applications in telecom wavelength, Lead chalcogenide colloidal NCs are optimum materials due to their unique optical, electronic and nonlinear properties. In this work, we experimentally demonstrate the integration of PbS nanocrystals into Si-based photonic structures like slot waveguides and ring resonators as optically pumped emitters for room temperature applications. In order to create such hybrid structures, the NCs were dissolved into polymer resists and drop cast on top of the device. Upon optical pumping, intense photoluminescence emission from the resonating modes is recorded at the output of the waveguide with transmission quality factors up to 14000. The polymer host material was investigated with respect to its ability to stabilize the NC's photoluminescence emission against degradation under ambient conditions. The waveguide-ring coupling efficiency was also investigated as function of the NCs concentrations blended into the polymer matrix. The integration of colloidal quantum dots into Silicon photonic structures as demonstrated in this work is a very versatile technique and thus opens a large range of applications utilizing the linear and nonlinear optical properties of PbS NCs at telecom wavelengths.

  11. Optimization of rhamnolipid production from Pseudomonas aeruginosa PBS towards application for microbial enhanced oil recovery.

    Science.gov (United States)

    Sharma, Rajni; Singh, Jagdish; Verma, Neelam

    2018-01-01

    The present work reveals the potential of biosurfactant producing P. aeruginosa PBS for microbial enhanced oil recovery (MEOR). The biosurfactant production medium and culture conditions were optimized using response surface methodology. The optimization of media components and process parameters was consecutively executed in two sets of experimental runs designed by central composite rotatable design (CCRD). The maximum biosurfactant yield was attained with 2% fresh inoculum of P. aeruginosa PBS in minimal salt medium (pH 7), possessing 2.17% sodium citrate as C-source and 0.5% yeast extract as N-source, after 48 h upon incubation at 30 °C/150 rpm. Under optimum conditions, biosurfactant yield was increased more than threefold and turned out to be 2.65 g/L as compared to 0.82 g/L under previous conditions. The biosurfactant was characterized as a glycolipid comprising of four rhamnolipid homologs (RhaRhaC 10 C 10 , RhaRhaC 8 C 10 , RhaRhaC 12 C 10 /RhaRhaC 10 C 12 , RhaC 10 C 10 ) by thin layer chromatography, fourier transform infrared spectroscopy, nuclear magnetic resonance and mass spectrometry. The produced biosurfactant was highly efficient for oil recovery application showing extreme reduction in surface tension of medium (71.80 to 23.76 mN/m), immense hydrocarbons emulsification capacity (50-60%) and greater stability at wide range of temperature (4-100 °C) and pH (4-10) along with an excellent (56.18 ± 1.59%) additional oil recovery in sand-pack column lab test.

  12. Project-Based Organizations and the New Spirit of Capitalism

    DEFF Research Database (Denmark)

    Jagd, Søren

    Luc Boltanski and Eve Chiapello’s analysis of recent changes in capitalism – Le nouvel esprit du capitalisme - is an important contribution to the sociological analysis of capitalism. The aim of this paper is to present their main argument. It is argued that a particular important aspect...... of their analysis is the ideal-typical model of the new spirit of capitalism, the ideological underpinning of project-based organizations in ‘The Project World’. It is argued that the ideal-typical model of the Project World is the most elaborated description of the ‘cultural code’ of the emergent form...... of capitalist organizations. Last, it is discussed how we may obtain empirical evidence to test the hypothesis of a major change in capitalist organizational forms as well as in the recent spirit of capitalism....

  13. Problem and Project Based Learning in Hybrid Spaces

    DEFF Research Database (Denmark)

    Ryberg, Thomas; Davidsen, Jacob; Hodgson, Vivien

    2016-01-01

    There is a need within networked learning to understand and conceptualise the interplay between digital and physical spaces or what we could term hybrid spaces. Therefore, we discuss a recent study of students from two different programmes who are engaged in long-term, group-based problem...... and project based learning. Based on interviews, workshops and observations of students’ actual group practices in open, shared and flexible spaces in Aalborg University (AAU), we identify and discuss how students incorporate networked and digital technologies into their group work and into the study places...... they create for themselves. We describe how in one of the programmes ‘nomadic’ groups of students used different technologies and spaces for ‘placemaking’. We then show how their experience and approach to collaborative work differs to that of the more static or ‘artisan’ groups of students in the other...

  14. Development of Entrepreneurship Competences from Project Based Learning Approaches

    Directory of Open Access Journals (Sweden)

    Lidia SÁNCHEZ GONZÁLEZ

    2017-02-01

    Full Text Available A key issue for any educational institution is to train individuals in such a way that they participate efficiently in their context. The current context where learning is carried out is digital era. With this landscape, and taking into account the current socioeconomic situation, it is necessary to increase students’ employability. This requires that what is taught in educational institutions fits with companies’ requirements. In this sense one of most common companies’ requirement is that students have knowledge about how to develop a project from scratch. In order to address this issue, the present paper poses the application of a project based learning methodology. This methodology is applied in an experiment that comprises two academic years. During each year, the students should develop complete projects working as teams and obtain final products. In this way, it was possible to develop competences that can be interesting for companies and also to increment students’ motivation.

  15. Project-based learning in geomatics at Aalborg University

    DEFF Research Database (Denmark)

    Höhle, Joachim

    2005-01-01

    The paper deals with the education in Geomatics at Aalborg University (AAU), Denmark. Since its foundation in 1974 AAU has used Project-Based Learning (PBL) as its educational model. In each of the 10 semesters a project has to be carried out by a group of students. The paper presents the ideas...... behind PBL and the use of this approach in Geomatics. Some examples of project work in the field of photogrammetry and remote sensing are given. Teachers and researchers at AAU recently published a book on the Aalborg PBL model, in which progress, diversity and challenges of the approach are documented....... Some of the findings in this investigation are presented. The on-campus education in Geomatics uses the Internet, and the paper informs about its application on campus. PBL is also practised at AAU's distance education programmes, which combine e-learning and weekend seminars on the campus. Experiences...

  16. PROJECT-BASED LEARNING IN ENGLISH FOR MEDICINE

    Directory of Open Access Journals (Sweden)

    Zorica Antić

    2012-06-01

    Full Text Available Project-based learning facilitates hands-on learning in student-driven investigations, resulting in high-quality, challenging activities. Students participate actively in projects that revolve around their interests, questions or needs. PBL also develops the 21st century skills including critical thinking, collaboration and communication. The essence of PBL is problem-solving, a key critical thinking skill. Since problem-solving is an integral part of medicine, projects represent a significant method of instruction in English for Medical Purposes. Depending on their individual interests and abilities, each student contributes to the whole group work and the final outcome. The approach also requires students to work in teams and to communicate their findings. Using real-life problems to motivate students, challenging them to think deeply about meaningful content, and enabling them to work collaboratively are practices that yield benefits for all students and their future careers.

  17. Project-based learning in a high school engineering program: A case study

    Science.gov (United States)

    France, Todd

    Generating greater student interest in science, technology, engineering, and mathematics (STEM) has been a major topic of discussion among educators, policymakers, and researchers in recent years, as increasing the number of graduates in these fields is widely considered a necessary step for sustaining the progress of today's society. Fostering this interest must occur before students reach college, and substantial efforts have been made to engage students at K-12 levels in STEM-focused learning. Attempts to involve students in engineering, a vital and growing profession, yet one in which students often have little experience, have frequently emphasized the design and construction of physical products, a practice supported by project-based learning. This thesis examines the environment of an engineering high school course that employed the project-based model. The course is part of a dedicated curricular program which aims to provide students with positive experiences in engineering-related activities while also preparing them for the rigors of college. A case study was conducted to provide insight into the benefits and drawbacks of the learning model. The study's outcomes are intended to provide guidance to educators participating in the design and/or facilitation of project-based activities, particularly those involved with engineering education. The research was performed using a qualitative approach. Long-term engagement with course participants was deemed critical to gaining a comprehensive understanding of the interactions and events that transpired on a daily basis. Nine educators involved with the program were interviewed, as were nineteen of the course's thirty-nine students. A wealth of other relevant data -- including surveys, field notes, and evaluations of student work -- was compiled for analysis as well. The study findings suggest that experiences in problem solving and teamwork were the central benefits of the course. Limitations existed due to a

  18. Project-Based Activity: Root of Research and Creative Thinking

    Science.gov (United States)

    Rambely, A. S.; Ahmad, R. R.; Majid, N.; M-Suradi, N. R.; Din, U. K. S.; A-Rahman, I.; Mohamed, F.; Rahim, F.; Abu-Hanifah, S.

    2013-01-01

    Decreasing of interest in mathematics and science subjects among students in Malaysia has been discussed lately. Applications of mathematics and science in real world settings might be able to facilitate increased interests in the subjects, especially in doing research. Therefore, the aim of this paper is to manifest that learning mathematics…

  19. Teaching Introductory Oceanography through Case Studies: Project based approach for general education students

    Science.gov (United States)

    Farnsworth, K. L.; House, M.; Hovan, S. A.

    2013-12-01

    A recent workshop sponsored by SERC-On the Cutting Edge brought together science educators from a range of schools across the country to discuss new approaches in teaching oceanography. In discussing student interest in our classes, we were struck by the fact that students are drawn to emotional or controversial topics such as whale hunting and tsunami hazard and that these kinds of topics are a great vehicle for introducing more complex concepts such as wave propagation, ocean upwelling and marine chemistry. Thus, we have developed an approach to introductory oceanography that presents students with real-world issues in the ocean sciences and requires them to explore the science behind them in order to improve overall ocean science literacy among non-majors and majors at 2 and 4 year colleges. We have designed a project-based curriculum built around topics that include, but are not limited to: tsunami hazard, whale migration, ocean fertilization, ocean territorial claims, rapid climate change, the pacific trash patch, overfishing, and ocean acidification. Each case study or project consists of three weeks of class time and is structured around three elements: 1) a media analysis; 2) the role of ocean science in addressing the issue; 3) human impact/response. Content resources range from textbook readings, popular or current print news, documentary film and television, and data available on the world wide web from a range of sources. We employ a variety of formative assessments for each case study in order to monitor student access and understanding of content and include a significant component of in-class student discussion and brainstorming guided by faculty input to develop the case study. Each study culminates in summative assessments ranging from exams to student posters to presentations, depending on the class size and environment. We envision this approach for a range of classroom environments including large group face-to-face instruction as well as hybrid

  20. Cadillac Desert: Water and the Transformation of Nature. A Discussion and Viewer's Guide to the PBS Series.

    Science.gov (United States)

    McDowell, Ceasar L.; Reisner, Marc; Bonk, Laura; Wisehart, Bob

    Cadillac Desert is a four-part Public Broadcasting Service (PBS) video series on the remaking of America's West through startling feats of engineering and the consequences that this manipulation of water and nature has wrought. This guide is meant to serve as a resource for discussing the issues raised in the series. The first part of the guide…

  1. Structure, transport and photoconductance of PbS quantum dot monolayers functionalized with a copper phthalocyanine derivative

    NARCIS (Netherlands)

    André, A.; Theurer, C.; Lauth, J.D.; Maiti, S.; Hodas, M.; Samadi Khoshkhoo, M.; Kinge, S; Meixner, A. J.; Schreiber, F.; Siebbeles, L.D.A.; Braun, K; Scheele, M.

    2017-01-01

    We simultaneously surface-functionalize PbS nanocrystals with Cu 4,4′,4′′,4′′′-tetraaminophthalocyanine and assemble this hybrid material into macroscopic monolayers. Electron microscopy and X-ray scattering reveal a granular mesocrystalline structure with strong coherence between the atomic

  2. Spin-coating deposition of PbS and CdS thin films for solar cell application

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Jayesh; Mighri, Frej [Laval University, CREPEC, Department of Chemical Engineering, Quebec, QC (Canada); Ajji, Abdellah [Ecole Polytechnique, CREPEC, Chemical Engineering Department, Montreal, QC (Canada); Tiwari, Devendra; Chaudhuri, Tapas K. [Charotar University of Science and Technology (CHARUSAT), Dr. K.C. Patel Research and Development Centre, Anand District, Gujarat (India)

    2014-12-15

    In this work, we describe a simple spin-coating deposition technique for lead sulphide (PbS) and cadmium sulphide (CdS) films from a methanolic metal-thiourea complex. The characterization of the films by X-ray diffraction and X-ray photoelectron spectroscopy techniques revealed that pure cubic phase PbS and CdS layers were formed via this method. As shown by atomic force microscopy and scanning electron microscopy results, both films were homogeneous and presented a smooth surface. Optical properties showed that the energy band gap of PbS and CdS films were around 1.65 and 2.5 eV, respectively. The PbS film is p-type in nature with an electrical conductivity of around 0.8 S/cm. The hole concentration and mobility were 2.35 x 10{sup 18} cm{sup -3} and 2.16 x 10{sup -3} cm{sup 2}/V/s, respectively, as determined from Hall measurement. Both films were used to develop a thin film solar cell device of graphite/PbS/CdS/ITO/glass. Device characterization showed the power conversion efficiency of around 0.24 %. The corresponding open circuit voltage, short circuit current and fill factor were 0.570 V, 1.32 mA/cm{sup 2} and 0.32, respectively. (orig.)

  3. Photoluminescence properties of powder and pulsed laser-deposited PbS nanoparticles in SiO2

    International Nuclear Information System (INIS)

    Dhlamini, M.S.; Terblans, J.J.; Ntwaeaborwa, O.M.; Ngaruiya, J.M.; Hillie, K.T.; Botha, J.R.; Swart, H.C.

    2008-01-01

    Thin films of lead sulfide (PbS) nanoparticles embedded in an amorphous silica (SiO 2 ) host were grown on Si(1 0 0) substrates at different temperatures by the pulsed laser deposition (PLD) technique. Surface morphology and photoluminescence (PL) properties of samples were analyzed with scanning electron microscopy (SEM) and a 458 nm Ar + laser, respectively. The PL data show a blue-shift from the normal emission at ∼3200 nm in PbS bulk to ∼560-700 nm in nanoparticulate PbS powders and thin films. Furthermore, the PL emission of the films was red-shifted from that of the powders at ∼560 to ∼660 nm. The blue-shifting of the emission wavelengths from 3200 to ∼560-700 nm is attributed to quantum confinement of charge carriers in the restricted volume of nanoparticles, while the red-shift between powders and thin-film PbS nanoparticles is speculated to be due to an increase in the defect concentration. The red-shift increased slightly with an increase in deposition temperature, which suggests that there has been a relative growth in particle sizes during the PLD of the films at higher temperatures. Generally, the PL emission of the powders was more intense than that of the films, although the intensity of some of the films was improved marginally by post-deposition annealing at 400 deg. C. This paper compares the PL properties of powder and pulsed laser-deposited thin films of PbS nanoparticles and the effects of deposition temperatures

  4. The effect of water molecules on the thiol collector interaction on the galena (PbS) and sphalerite (ZnS) surfaces: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Long, Xianhao [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Chen, Ye, E-mail: fby18@126.com [College of Resources and Metallurgy, Guangxi University, Nanning 530004 (China); Chen, Jianhua, E-mail: jhchen@gxu.edu.cn [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); College of Resources and Metallurgy, Guangxi University, Nanning 530004 (China); Xu, Zhenghe; Liu, Qingxia [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 2V4 (Canada); Du, Zheng [National Supercomputing Center in Shenzhen, Shenzhen 518055 (China)

    2016-12-15

    Highlights: • Water adsorption has a greater effect on the electron distribution of ZnS surface than PbS surface. • Water adsorption decreases the reactivity of ZnS surface atoms but improves that of PbS. • Thiol collectors cannot interact with the hydrated ZnS surface. • The hydration has little influence on the interaction of thiol collectors with PbS surface. - Abstracts: In froth flotation the molecular interaction between reagents and mineral surfaces take place at the solid liquid interface. In this paper, the effect of water molecule on the three typical thiol collectors (xanthate, dithiocarbomate and dithiophosphate) interactions at the galena (PbS) and sphalerite (ZnS) surfaces has been studied adopting density functional theory (DFT). The results suggests that the presence of water molecule shows a greater influence on the electron distribution of ZnS surface than PbS surface, and reduce the reactivity of ZnS surface atoms but improves the reactivity of PbS surface atoms during the reaction with xanthate. Water adsorption could also reduce the covalent binding between Zn and S atoms but have little influence on Pb-S bond. In the presence of water, xanthate, dithiocarbomate (DTC) and dithiophosphate (DTP) could not adsorb on the sphalerite surface. And for galena (PbS) surface, the interaction of DTP is the strongest, then the DTC and the interaction of xanthate is the weakest. These results agree well with the flotation practice.

  5. Applying Cultural Project Based Learning to Develop Students’ Academic Writing

    Directory of Open Access Journals (Sweden)

    Lulus Irawati

    2015-06-01

    Full Text Available Writing is considered to be the most demanding and difficult skill for many college students, since there are some steps to be followed such as prewriting, drafting, editing, revising and publishing. The interesting topic like culture including lifestyle, costume, and custom is necessary to be offered in Academic Writing class. Accordingly, this article aims to elaborate the application of a cultural project based learning to develop students’ ability in academic writing. This descriptive qualitative research was conducted in Academic Writing class consisting of 20 students of the fourth semester. The students were divided into some groups, each consisting of 4-5 people assigned to make a cultural project within 6 weeks, in the form of essay. Each member of the groups has to create his/ her own essay and then compile the essays to be a mini-journal. Therefore, one group has one mini-journal consisting of 4-5 essays. To check the content of mini-journal, the lecturer also asked the groups to present in front of the class to get some suggestions, feedback, or comments.

  6. Software for project-based learning of robot motion planning

    Science.gov (United States)

    Moll, Mark; Bordeaux, Janice; Kavraki, Lydia E.

    2013-12-01

    Motion planning is a core problem in robotics concerned with finding feasible paths for a given robot. Motion planning algorithms perform a search in the high-dimensional continuous space of robot configurations and exemplify many of the core algorithmic concepts of search algorithms and associated data structures. Motion planning algorithms can be explained in a simplified two-dimensional setting, but this masks many of the subtleties and complexities of the underlying problem. We have developed software for project-based learning of motion planning that enables deep learning. The projects that we have developed allow advanced undergraduate students and graduate students to reflect on the performance of existing textbook algorithms and their own variations on such algorithms. Formative assessment has been conducted at three institutions. The core of the software used for this teaching module is also used within the Robot Operating System, a widely adopted platform by the robotics research community. This allows for transfer of knowledge and skills to robotics research projects involving a large variety robot hardware platforms.

  7. SU-E-T-188: Commission of World 1st Commercial Compact PBS Proton System

    Energy Technology Data Exchange (ETDEWEB)

    Ding, X; Patel, B; Song, X; Syh, J; Syh, J; Zhang, J; Freund, D; Rosen, L; Wu, H [Willis-Knighton Medical Center, Shreveport, LA (United States)

    2015-06-15

    Purpose: ProteusONE is the 1st commercial compact PBS proton system with an upstream scanning gantry and C230 cyclotron. We commissioned XiO and Raystation TPS simultaneously. This is a summary of beam data collection, modeling, and verification and comparison without range shiter for this unique system with both TPS. Methods: Both Raystation and XiO requires the same measurements data: (i) integral depth dose(IDDs) of single central spot measured in water tank; (ii) absolute dose calibration measured at 2cm depth of water with mono-energetic 10×10 cm2 field with spot spacing 4mm, 1MU per spot; and (iii) beam spot characteristics in air at 0cm and ± 20cm away from ISO. To verify the beam model for both TPS, same 15 cube plans were created to simulate different treatment sites, target volumes and positions. PDDs of each plan were measured using a Multi-layer Ionization Chamber(MLIC), absolute point dose verification were measured using PPC05 in water tank and patient-specific QA were measured using MatriXX PT, a 2D ion chamber array. Results: All the point dose measurements at midSOBP were within 2% for both XiO and Raystation. However, up to 5% deviations were observed in XiO’s plans at shallow depth while within 2% in Raystation plans. 100% of the ranges measured were within 1 mm with maximum deviation of 0.5 mm. 20 patient specific plan were generated and measured in 3 planes (distal, proximal and midSOBP) in Raystation. The average of gamma index is 98.7%±3% with minimum 94% Conclusions: Both TPS were successfully commissioned and can be safely deployed for clinical use for ProteusONE. Based on our clinical experience in PBS planning, user interface, function and workflow, we preferably use Raystation as our main clinical TPS. Gamma Index >95% at 3%/3 mm criteria is our institution action level for patient specific plan QAs.

  8. Systemic impediments to the implementation of Project Based Learning in middle and high school settings

    Science.gov (United States)

    Bouilly, Delphine

    This study examines the potential structural impediments to the reform movement of Project Based Learning (PBL) that are presented to teachers by the inherent nature of the school system, as well as the ways in which teachers address these systemic barriers when attempting to implement PBL in their classrooms. Much of the current research that is aimed at investigating the transition from traditional teacher-centered learning to student-centered PBL---whether PBL as problem based or project based learning---has focused on the transition issues at the level of individual teacher/student. Systemic barriers, on the other hand, are those features that are inherent to the structure of the system, and that pose---by their very nature---physical and/or political circumstances that are inconsistent with the student-centered and collaborative goals of PBL. It is not enough for teachers, parents, students, and administrators to be philosophically aligned with PBL, if the encompassing school system is structurally incompatible with the method. This study attempts to make the structural impediments to PBL explicit, to determine whether or not the existing school system is amenable to the successful implementation of PBL. Because the universal features of PBL coupled with the ubiquity of factory-model schools is likely to create recurring themes, it is plausible that this study may in fact be analytically generalizable to situations beyond those described by the populations and contexts in this set of purposive, multiple cases. One of the themes that emerged from this study was the role of rural poverty as an underlying cause of student apathy. More research may be needed to see whether science, as taught through PBL and in collaboration with practical arts courses, might be able to address some of the social, gendered, and educational needs of impoverished rural students and their families.

  9. Effect of precursors on the solid-state synthesis of semiconducting PbS nanostructures

    Directory of Open Access Journals (Sweden)

    Sujata Kasabe

    2013-03-01

    Full Text Available In this communication, we report facile and economical in-situ preparation of lead sulphide (PbS nanorods and nanocubes within the Polyphenylene sulphide (PPS matrix. PPS plays a dual role in the synthesis of the resultant nanostructures as - (i a chalcogen source and (ii a stabilizing matrix. We studied the effect of change of lead precursor from lead nitrate to acetate on the morphological properties of the resultant nanostructures. The effect of molar ratios of the reactants (1:1, 1:5, 1:10, 1:15 and 1:20 on the morphology of the products was also studied. The resultant nanocomposites were characterized by various physico-chemical techniques like X-ray Diffractometry (XRD, SEM equipped with EDAX, TEM and UV-Visible spectroscopy. The prima-facie observations suggest effective formation and subsequent entrapment of lead sulphide nanorods and nanocubes, respectively, when lead acetate and lead nitrate precursors were used. Additionally, simultaneous occurrence of nanocrystalline cubic lead as an impurity phase is noticed in case of heated admixtures for both the precursors.

  10. Heterojunction PbS nanocrystal solar cells with oxide charge-transport layers.

    Science.gov (United States)

    Hyun, Byung-Ryool; Choi, Joshua J; Seyler, Kyle L; Hanrath, Tobias; Wise, Frank W

    2013-12-23

    Oxides are commonly employed as electron-transport layers in optoelectronic devices based on semiconductor nanocrystals, but are relatively rare as hole-transport layers. We report studies of NiO hole-transport layers in PbS nanocrystal photovoltaic structures. Transient fluorescence experiments are used to verify the relevant energy levels for hole transfer. On the basis of these results, planar heterojunction devices with ZnO as the photoanode and NiO as the photocathode were fabricated and characterized. Solution-processed devices were used to systematically study the dependence on nanocrystal size and achieve conversion efficiency as high as 2.5%. Optical modeling indicates that optimum performance should be obtained with thinner oxide layers than can be produced reliably by solution casting. Room-temperature sputtering allows deposition of oxide layers as thin as 10 nm, which enables optimization of device performance with respect to the thickness of the charge-transport layers. The best devices achieve an open-circuit voltage of 0.72 V and efficiency of 5.3% while eliminating most organic material from the structure and being compatible with tandem structures.

  11. Dissociation of water and Acetic acid on PbS from first principles

    Science.gov (United States)

    Satta, Alessandra; Ruggerone, Paolo; de Giudici, Giovanni

    2008-03-01

    The adsorption of complex molecules at mineral surfaces are crucial ingredients for understanding the mechanisms that rule the interaction between minerals and the biosphere and for predicting both the stability and the reactivity of minerals. The present work focuses mainly on the early stages of different adsorption reactions occurring at both the cleavage surface and a high-index vicinal surface of galena (PbS). We have studied the dissociation mechanism of water and acetic acid on the galena surfaces by means of ab initio calculations within the framework of the density functional theory in the generalized gradient approximation and of pseudopotential approach. The calculated adsorption energies of the molecules indicate the stepped surface as the most reactive, as expected. The free energy surface during the reaction process has been explored via metadynamics[1]. The optimized configurations of both reactants and products obtained, were then used to accurately calculate the dissociation energy via the Nudge Elastic Band method[2]. [1] A. Laio and M. Parrinello, PNAS 99, 12562 (2002). [2] G. Mills and H. Jonsson, Phys. Rev. Lett. 72, 1124 (1994).

  12. Heterojunction PbS Nanocrystal Solar Cells with Oxide Charge-Transport Layers

    KAUST Repository

    Hyun, Byung-Ryool

    2013-12-23

    Oxides are commonly employed as electron-transport layers in optoelectronic devices based on semiconductor nanocrystals, but are relatively rare as hole-transport layers. We report studies of NiO hole-transport layers in PbS nanocrystal photovoltaic structures. Transient fluorescence experiments are used to verify the relevant energy levels for hole transfer. On the basis of these results, planar heterojunction devices with ZnO as the photoanode and NiO as the photocathode were fabricated and characterized. Solution-processed devices were used to systematically study the dependence on nanocrystal size and achieve conversion efficiency as high as 2.5%. Optical modeling indicates that optimum performance should be obtained with thinner oxide layers than can be produced reliably by solution casting. Roomerature sputtering allows deposition of oxide layers as thin as 10 nm, which enables optimization of device performance with respect to the thickness of the charge-transport layers. The best devices achieve an open-circuit voltage of 0.72 V and efficiency of 5.3% while eliminating most organic material from the structure and being compatible with tandem structures. © 2013 American Chemical Society.

  13. Interconnected TiO2 Nanowire Networks for PbS Quantum Dot Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Fan Xu

    2012-01-01

    Full Text Available We present a simple method for the fabrication of an interconnected porous TiO2 nanostructured film via dip coating in a colloidal suspension of ultrathin TiO2 nanowires followed by high-temperature annealing. The spheroidization of the nanowires and the fusing of the loosely packed nanowire films at the contact points lead to the formation of nanopores. Using this interconnected TiO2 nanowire network for electron transport, a PbS/TiO2 heterojunction solar cell with a large short-circuit current of 2.5 mA/cm2, a Voc of 0.6 V, and a power conversion efficiency of 5.4% is achieved under 8.5 mW/cm2 white light illumination. Compared to conventional planar TiO2 film structures, these results suggest superior electron transport properties while still providing the large interfacial area between PbS quantum dots and TiO2 required for efficient exciton dissociation.

  14. CdO necklace like nanobeads decorated with PbS nanoparticles: Room temperature LPG sensor

    Energy Technology Data Exchange (ETDEWEB)

    Sonawane, N.B. [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon, 425001 M.S. (India); K.A.M.P. & N.K.P. Science College, Pimpalner, Sakri, Dhule, M.S. (India); Baviskar, P.K. [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon, 425001 M.S. (India); Ahire, R.R. [S.G. Patil Science, Sakri, Dhule, M.S. (India); Sankapal, B.R., E-mail: brsankapal@gmail.com [Nano Materials and Device Laboratory, Department of Applied Physics, Visvesvaraya National Institute of Technology, South Ambazari Road, Nagpur, 440010 M.S. (India)

    2017-04-15

    Simple chemical route has been employed to grow interconnected nanobeads of CdO having necklace like structure through air annealing of cadmium hydroxide nanowires. This nanobeads of n-CdO with high surface area has been decorated with p-PbS nanoparticles resulting in the formation of nano-heterojunction which has been utilized effectively as room temperature liquefied petroleum gas (LPG) sensor. The room temperature gas response towards C{sub 2}H{sub 5}OH, Cl{sub 2}, NH{sub 3}, CO{sub 2} and LPG was investigated, among which LPG exhibits significant response. The maximum gas response of 51.10% is achieved with 94.54% stability upon exposure of 1176 ppm concentration of LPG at room temperature (27 °C). The resulting parameters like gas response, response and recovery time along with stability studies has been studied and results are discussed herein. - Highlights: • Conversion of Cd(OH){sub 2} nanowires to CdO nanonecklace by air annealing at 290 °C. • Decoration of PbS nanoparticles over CdO nanobeads by SILAR method. • Formation of n-CdO/p-PbS nano-heterojunction as room temperature LPG sensor. • Maximum gas response of 51.10% with 94.54% stability.

  15. Problems and Projects Based Approach For Analog Electronic Circuits' Course

    Directory of Open Access Journals (Sweden)

    Vahé Nerguizian

    2009-04-01

    Full Text Available New educational methods and approaches are recently introduced and implemented at several North American and European universities using Problems and Projects Based Approach (PPBA. The PPBA employs a teaching technique based mostly on competences/skills rather than only on knowledge. This method has been implemented and proven by several pedagogical instructors and authors at several educational institutions. This approach is used at different disciplines such as medicine, biology, engineering and many others. It has the advantage to improve the student's skills and the knowledge retention rate, and reflects the 21st century industrial/company needs and demands. Before implementing this approach to a course, a good resources preparation and planning is needed upfront by the responsible or instructor of the course to achieve the course and students related objectives. This paper presents the preparation, the generated documentation and the implementation of a pilot project utilizing PPBA education for a second year undergraduate electronic course over a complete semester, and for two different class groups (morning and evening groups. The outcome of this project (achieved goals, observed difficulties and lessons learned is presented based on different tools such as students 'in class' communication and feedback, different course evaluation forms and the professor/instructor feedback. Resources, challenges, difficulties and recommendations are also assessed and presented. The impact, the effect and the results (during and at the end of the academic fall session of the PPBA on students and instructor are discussed, validated, managed and communicated to help other instructor in taking appropriate approach decisions with respect to this new educational approach compared to the classical one.

  16. Project-based faculty development for e-learning.

    Science.gov (United States)

    Vyas, Rashmi; Faith, Minnie; Selvakumar, Dhayakani; Pulimood, Anna; Lee, Mary

    2016-12-01

    The Christian Medical College, Vellore, in collaboration with Tufts University, Boston, conducted an advanced workshop in e-learning for medical faculty members in India. E-learning can enhance educational reforms for today's computer-literate generation, and keep faculty members up to speed in a rapidly changing world. The purpose of this paper is to report on the design and evaluation of a project-based faculty member development programme focused on developing faculty members as educators and as peer trainers who can use e-learning for educational reforms. During a 2-day workshop, 29 participants in groups of two or three developed 13 e-learning projects for implementation in their institutions. Evaluation of the workshop was through written feedback from the participants at the end of the workshop and by telephone interview with one participant from each project group at the end of one year. Content analysis of qualitative data was perfomed. The participants reported that they were motivated to implement e-learning projects and recognised the need for and usefulness of e-learning. The majority of projects (10 out of 13) that were implemented 'to some extent' or 'to a great extent' faced challenges with a lack of resources and administrative support, but faculty members were able to overcome them. E-learning can enhance educational reforms for today's computer-literate generation IMPLICATIONS: Designing feasible e-learning projects in small groups and obtaining hands-on experience with e-learning tools enhance the effectiveness of subsequent implementation. To successfully incorporate e-learning when designing educational reforms, faculty member training, continuing support and infrastructure facilities are essential. © 2016 John Wiley & Sons Ltd.

  17. Project-based production and project management: Findings and trends in research on temporary systems in multiple contexts

    Directory of Open Access Journals (Sweden)

    Tinus Pretorius

    2014-02-01

    Full Text Available Globalisation is challenging almost every aspect of the political, economic, social and technological environment. Organisations, whether public or private, have to adapt their strategies and operations to stay competitive and efficient. Historically, organisations adopted project-based operations as a mode to stay competitive, although the applications tended to be the oneoff type of operations such as construction and system development projects (Edum-Fotwe & McCaffer, 2000. As the world changed from an industrially driven to a more knowledge driven economy and the pace of continuous change became more intense, organisations adopted a project-based mode of operations on a broader scale. The knowledge economy lead to the creation of many service orientated industries. Organisations started facing portfolios of projects where the nature of these projects differed in technological complexity, urgency, customer value and social impact (Gutjahr & Froeschl, 2013. Based on their experience with more technically orientated projects, organisations focused their attention more intensely on new project management methods, tools and processes and not necessarily on the human and organisational interfaces. This paradigm changed however, especially since the 1980s and more and more organisations adopted temporary organisational forms (Bakker, 2010 in order to improve their competitiveness. The contributions in this special edition of the South African Journal of Economic and Management Sciences have a common focus on the importance of the human and organisational interface of project-based operations on project success. The purpose of this concluding article is to analyse the findings and recommendations in these papers and to detect trends and future research opportunities in the field of project-based operations.

  18. Interfacial dynamic surface traps of lead sulfide (PbS) nanocrystals: test-platform for interfacial charge carrier traps at the organic/inorganic functional interface

    Science.gov (United States)

    Kim, Youngjun; Ko, Hyungduk; Park, Byoungnam

    2018-04-01

    Nanocrystal (NC) size and ligand dependent dynamic trap formation of lead sulfide (PbS) NCs in contact with an organic semiconductor were investigated using a pentacene/PbS field effect transistor (FET). We used a bilayer pentacene/PbS FET to extract information of the surface traps of PbS NCs at the pentacene/PbS interface through the field effect-induced charge carrier density measurement in the threshold and subthreshold regions. PbS size and ligand dependent trap properties were elucidated by the time domain and threshold voltage measurements in which threshold voltage shift occurs by carrier charging and discharging in the trap states of PbS NCs. The observed threshold voltage shift is interpreted in context of electron trapping through dynamic trap formation associated with PbS NCs. To the best of our knowledge, this is the first demonstration of the presence of interfacial dynamic trap density of PbS NC in contact with an organic semiconductor (pentacene). We found that the dynamic trap density of the PbS NC is size dependent and the carrier residence time in the specific trap sites is more sensitive to NC size variation than to NC ligand exchange. The probing method presented in the study offers a means to investigate the interfacial surface traps at the organic-inorganic hetero-junction, otherwise understanding of the buried surface traps at the functional interface would be elusive.

  19. Millisecond-Timescale Monitoring of PbS Nanoparticle Nucleation and Growth Using Droplet-Based Microfluidics.

    Science.gov (United States)

    Lignos, Ioannis; Stavrakis, Stavros; Kilaj, Ardita; deMello, Andrew J

    2015-08-26

    The early-time kinetics (conversion of precursor species to PbS crystals, followed by the growth of the formed particles. The growth kinetics of the PbS nanoparticles follow the Lifshitz-Slyozov-Wagner model for Ostwald ripening, allowing direct estimation of the rate constants for the process. In addition, the extraction of absorption spectra of ultrasmall quantum dots is demonstrated for first time in an online manner. The droplet-based microfluidic platform integrated with online spectroscopic analysis provides a new tool for the quantitative extraction of high temperature kinetics for systems with rapid nucleation and growth stages. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Spontaneous interfacial reaction between metallic copper and PBS to form cupric phosphate nanoflower and its enzyme hybrid with enhanced activity.

    Science.gov (United States)

    He, Guangli; Hu, Weihua; Li, Chang Ming

    2015-11-01

    We herein report the spontaneous interfacial reaction between copper foil with 0.01 M phosphate buffered saline (PBS) to form free-standing cupric phosphate (Cu3(PO4)2) nanoflowers at ambient temperature. The underlying chemistry was thoroughly investigated and it is found that the formation of nanoflower is synergistically caused by dissolved oxygen, chlorine ions and phosphate ions. Enzyme-Cu3(PO4)2 hybrid nanoflower was further prepared successfully by using an enzyme-dissolving PBS solution and the enzymes in the hybrid exhibit enhanced biological activity. This work provides a facile route for large-scale synthesis of hierarchical inorganic and functional protein-inorganic hybrid architectures via a simple one-step solution-immersion reaction without using either template or surfactant, thus offering great potential for biosensing application among others. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Molecular and Supramolecular Changes in Polybutylene Succinate (PBS and Polybutylene Succinate Adipate (PBSA Copolymer during Degradation in Various Environmental Conditions

    Directory of Open Access Journals (Sweden)

    Michał Puchalski

    2018-03-01

    Full Text Available In this paper, the influence of the various degradation conditions, on the molecular and supramolecular structure of polybutylene succinate (PBS and polybutylene succinate adipate (PBSA copolymer during degradation is described. The experiment was carried out by the use of injection molded samples and normalized conditions of biodegradation in soil, composting and artificial weathering. Materials were studied by size-exclusion chromatography (SEC coupled with multiangle laser light scattering (MALLS detection and wide-angle X-ray diffraction (WAXD. Additionally, the physical and mechanical properties of the samples were determined. The performed experiments clearly show difference impacts of the selected degradation conditions on the macroscopic, supramolecular and molecular parameters of the studied aliphatic polyesters. The structural changes in PBS and PBSA explain the observed changes in the physical and mechanical properties of the obtained injection molded samples.

  2. Fabrication of PbS quantum dots and their applications in solar cells based on ZnO nanorod arrays

    Science.gov (United States)

    Kumar, Dinesh; Chaudhary, Sujeet; Pandya, Dinesh K.

    2018-05-01

    An efficient, inexpensive and large area scalable approach based on sol-gel technique is presented to fabricate quantum dots (QDs) of PbS. Size of the QDs is tuned by the varying the bath concentrations in the range of 50-200 mM. Transmission electron microscopy (TEM) studies confirm the growth of spherically shaped ˜5.6 nm QDs at 50 mM bath concentration. The optical bandgap of the QDs is found to be ˜0.9 eV and corresponds to the size obtained from TEM studies. ZnO/PbS solar cells are fabricated by sensitizing the ZnO nanorods with PbS QDs. The fabricated solar cells demonstrate the highest open circuit voltage ˜200 mV and short circuit current density ˜0.81 µA/cm2.

  3. Optimization of synthesis conditions of PbS thin films grown by chemical bath deposition using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Yücel, Ersin, E-mail: dr.ersinyucel@gmail.com [Department of Physics, Faculty of Arts and Sciences, Mustafa Kemal University, 31034 Hatay (Turkey); Yücel, Yasin; Beleli, Buse [Department of Chemistry, Faculty of Arts and Sciences, Mustafa Kemal University, 31034 Hatay (Turkey)

    2015-09-05

    Highlights: • For the first time, RSM and CCD used for optimization of PbS thin film. • Tri-sodium citrate, deposition time and temperature were independent variables. • PbS thin film band gap value was 2.20 eV under the optimum conditions. • Quality of the film was improved after chemometrics optimization. - Abstract: In this study, PbS thin films were synthesized by chemical bath deposition (CBD) under different deposition parameters. Response surface methodology (RSM) was used to optimize synthesis parameters including amount of tri-sodium citrate (0.2–0.8 mL), deposition time (14–34 h) and deposition temperature (26.6–43.4 °C) for deposition of the films. 5-level-3-factor central composite design (CCD) was employed to evaluate effects of the deposition parameters on the response (optical band gap of the films). The significant level of both the main effects and the interaction are investigated by analysis of variance (ANOVA). The film structures were characterized by X-ray diffractometer (XRD). Morphological properties of the films were studied with a scanning electron microscopy (SEM). The optical properties of the films were investigated using a UV–visible spectrophotometer. The optimum amount of tri-sodium citrate, deposition time and deposition temperature were found to be 0.7 mL, 18.07 h and 30 °C respectively. Under these conditions, the experimental band gap of PbS was 2.20 eV, which is quite good correlation with value (1.98 eV) predicted by the model.

  4. Magneto-optical controlled transmittance alteration of PbS quantum dots by moderately applied magnetic fields at room temperature

    International Nuclear Information System (INIS)

    Singh, Akhilesh K.; Barik, Puspendu; Ullrich, Bruno

    2014-01-01

    We observed changes of the transmitted monochromatic light passing through a colloidal PbS quantum dot film on glass owing to an applied moderate (smaller than 1 T) magnetic field under ambient conditions. The observed alterations show a square dependence on the magnetic field increase that cannot be achieved with bulk semiconductors. The findings point to so far not recognized application potentials of quantum dots

  5. Optimization of synthesis conditions of PbS thin films grown by chemical bath deposition using response surface methodology

    International Nuclear Information System (INIS)

    Yücel, Ersin; Yücel, Yasin; Beleli, Buse

    2015-01-01

    Highlights: • For the first time, RSM and CCD used for optimization of PbS thin film. • Tri-sodium citrate, deposition time and temperature were independent variables. • PbS thin film band gap value was 2.20 eV under the optimum conditions. • Quality of the film was improved after chemometrics optimization. - Abstract: In this study, PbS thin films were synthesized by chemical bath deposition (CBD) under different deposition parameters. Response surface methodology (RSM) was used to optimize synthesis parameters including amount of tri-sodium citrate (0.2–0.8 mL), deposition time (14–34 h) and deposition temperature (26.6–43.4 °C) for deposition of the films. 5-level-3-factor central composite design (CCD) was employed to evaluate effects of the deposition parameters on the response (optical band gap of the films). The significant level of both the main effects and the interaction are investigated by analysis of variance (ANOVA). The film structures were characterized by X-ray diffractometer (XRD). Morphological properties of the films were studied with a scanning electron microscopy (SEM). The optical properties of the films were investigated using a UV–visible spectrophotometer. The optimum amount of tri-sodium citrate, deposition time and deposition temperature were found to be 0.7 mL, 18.07 h and 30 °C respectively. Under these conditions, the experimental band gap of PbS was 2.20 eV, which is quite good correlation with value (1.98 eV) predicted by the model

  6. Realization of PbS thin films by reactive evaporation technique for possible opto-electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    A, Abhilash, E-mail: abhiltp@cusat.ac.in; Nair, Aparna S.; S, Rajasree; E, Hiba Rahman; Pradeep, B. [Solid State Physics Laboratory, Department of Physics, Cochin University of Science and Technology, Kochi-682022 (India)

    2015-06-24

    Stoichiometric Lead sulphide (PbS) thin films were successfully prepared on glass substrates by reactive evaporation technique. Elemental evaporation of lead and sulphur taken in different sources onto substrates held at temperature of 400±5K employed in the present study. The structural as well as compositional studies compromises compound formation. Electrical transport properties and optical co-efficient were evaluated from appropriate characterization techniques.

  7. High-performance PbS quantum dot vertical field-effect phototransistor using graphene as a transparent electrode

    Science.gov (United States)

    Che, Yongli; Zhang, Yating; Cao, Xiaolong; Song, Xiaoxian; Zhang, Haiting; Cao, Mingxuan; Dai, Haitao; Yang, Junbo; Zhang, Guizhong; Yao, Jianquan

    2016-12-01

    Solution processed photoactive PbS quantum dots (QDs) were used as channel in high-performance near-infrared vertical field-effect phototransistor (VFEpT) where monolayer graphene embedded as transparent electrode. In this vertical architecture, the PbS QD channel was sandwiched and naturally protected between the drain and source electrodes, which made the device ultrashort channel length (110 nm) simply the thickness of the channel layer. The VFEpT exhibited ambipolar operation with high mobilities of μe = 3.5 cm2/V s in n-channel operation and μh = 3.3 cm2/V s in p-channel operation at low operation voltages. By using the photoactive PbS QDs as channel material, the VFEpT exhibited good photoresponse properties with a responsivity of 4.2 × 102 A/W, an external quantum efficiency of 6.4 × 104% and a photodetectivity of 2.1 × 109 Jones at the light irradiance of 36 mW/cm2. Additionally, the VFEpT showed excellent on/off switching with good stability and reproducibility and fast response speed with a short rise time of 12 ms in n-channel operation and 10.6 ms in p-channel operation. These high mobilities, good photoresponse properties and simplistic fabrication of our VFEpTs provided a facile route to the high-performance inorganic photodetectors.

  8. Field effect transistors and phototransistors based upon p-type solution-processed PbS nanowires

    Science.gov (United States)

    Giraud, Paul; Hou, Bo; Pak, Sangyeon; Inn Sohn, Jung; Morris, Stephen; Cha, SeungNam; Kim, Jong Min

    2018-02-01

    We demonstrate the fabrication of solution processed highly crystalline p-type PbS nanowires via the oriented attachment of nanoparticles. The analysis of single nanowire field effect transistor (FET) devices revealed a hole conduction behaviour with average mobilities greater than 30 cm2 V-1 s-1, which is an order of magnitude higher than that reported to date for p-type PbS colloidal nanowires. We have investigated the response of the FETs to near-infrared light excitation and show herein that the nanowires exhibited gate-dependent photo-conductivities, enabling us to tune the device performances. The responsivity was found to be greater than 104 A W-1 together with a detectivity of 1013 Jones, which benefits from a photogating effect occurring at negative gate voltages. These encouraging detection parameters are accompanied by relatively short switching times of 15 ms at positive gate voltages, resulting from a combination of the standard photoconduction and the high crystallinity of the nanowires. Collectively, these results indicate that solution-processed PbS nanowires are promising nanomaterials for infrared photodetectors as well as p-type nanowire FETs.

  9. Electron-Phonon Coupling and Resonant Relaxation from 1D and 1P States in PbS Quantum Dots.

    Science.gov (United States)

    Kennehan, Eric R; Doucette, Grayson S; Marshall, Ashley R; Grieco, Christopher; Munson, Kyle T; Beard, Matthew C; Asbury, John B

    2018-05-31

    Observations of the hot-phonon bottleneck, which is predicted to slow the rate of hot carrier cooling in quantum confined nanocrystals, have been limited to date for reasons that are not fully understood. We used time-resolved infrared spectroscopy to directly measure higher energy intraband transitions in PbS colloidal quantum dots. Direct measurements of these intraband transitions permitted detailed analysis of the electronic overlap of the quantum confined states that may influence their relaxation processes. In smaller PbS nanocrystals, where the hot-phonon bottleneck is expected to be most pronounced, we found that relaxation of parity selection rules combined with stronger electron-phonon coupling led to greater spectral overlap of transitions among the quantum confined states. This created pathways for fast energy transfer and relaxation that may bypass the predicted hot-phonon bottleneck. In contrast, larger, but still quantum confined nanocrystals did not exhibit such relaxation of the parity selection rules and possessed narrower intraband states. These observations were consistent with slower relaxation dynamics that have been measured in larger quantum confined systems. These findings indicated that, at small radii, electron-phonon interactions overcome the advantageous increase in energetic separation of the electronic states for PbS quantum dots. Selection of appropriately sized quantum dots, which minimize spectral broadening due to electron-phonon interactions while maximizing electronic state separation, is necessary to observe the hot-phonon bottleneck. Such optimization may provide a framework for achieving efficient hot carrier collection and multiple exciton generation.

  10. Biological conversion of anglesite (PbSO(4)) and lead waste from spent car batteries to galena (PbS).

    Science.gov (United States)

    Weijma, Jan; De Hoop, Klaas; Bosma, Wobby; Dijkman, Henk

    2002-01-01

    Lead paste, a solid mixture containing PbSO(4), PbO(2), PbO/Pb(OH)(2) precipitate, and elemental Pb, is one of the main waste fractions from spent car batteries. Biological sulfidation represents a new process for recovery of lead from this waste. In this process the lead salts in lead paste are converted to galena (PbS) by sulfate-reducing bacteria. This paper investigates a continuous process for sulfidation of anglesite (PbSO(4)), the main constituent of lead paste, and lead paste, consisting of a laboratory-scale gas-lift bioreactor to which a slurry of anglesite or lead paste was supplied. Sulfate or elemental sulfur was added as an additional sulfur source. Hydrogen gas served as an electron donor for the biological reduction of sulfate and elemental sulfur to sulfide by sulfate- and sulfur-reducing bacteria. Anglesite was almost completely converted to galena at a loading rate of 19 kg of PbSO(4) m(-)(3) day(-)(1), producing a sludge of which the crystalline lead phases consisted of >98% PbS (galena) and 1-2% elemental Pb. With lead paste, stable sulfidation rates of up to 17 kg of lead paste m(-)(3) day(-)(1) were demonstrated, producing a sludge of which the crystalline lead phases consisted of an estimated >96% PbS, 1-2% elemental Pb, and 1-2% PbO(2).

  11. Solution-processed nanocrystalline PbS on paper substrate with pencil traced electrodes as visible photodetector

    Science.gov (United States)

    Vankhade, Dhaval; Chaudhuri, Tapas K.

    2018-04-01

    Paper-based PbS photodetector sensitive in the visible spectrum is reported. Nanocrystalline PbS-on-paper devices are fabricated by a spin coating method on white paper (300 GSM) from a methanolic precursor solution. Photodetector cells of gap 0.2 cm and length 0.5 cm are prepared by drawing contacts by monolithic cretacolor 8B pencil. X-ray diffractometer confirmed the deposition of nanocrystalline PbS films with 14 nm crystallites. The SEM illustrated the uniform coating of nanocrystalline PbS thin films on cellulose fibres of papers having an average thickness of fibres are 10 µm. The linear J-V characteristics in dark and under illumination of light using graphite trace on nanocrystalline PbS-on-paper shows good ohmic contact. The resistivity of pencil trace is 30 Ω.cm. Spectral response measurements of photodetector reveal the excellent sensitivity from 400 to 700 nm with a peak at 550 nm. The best responsivity anddetectivity are 0.7 A/W and 1.4 × 1012 Jones respectively. These paper-based low-cost photodetectors devices have fast photoresponse and recovery without baseline deviation.

  12. Supercritical synthesis and in situ deposition of PbS nanocrystals with oleic acid passivation for quantum dot solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tavakoli, M.M. [Department of Materials Science and Engineering, Sharif University of Technology, 14588 Tehran (Iran, Islamic Republic of); Simchi, A., E-mail: simchi@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, 14588 Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, 14588 Tehran (Iran, Islamic Republic of); Aashuri, H. [Department of Materials Science and Engineering, Sharif University of Technology, 14588 Tehran (Iran, Islamic Republic of)

    2015-04-15

    Colloidal quantum dot solar cells have recently attracted significant attention due to their low-processing cost and surging photovoltaic performance. In this paper, a novel, reproducible, and simple solution-based process based on supercritical fluid toluene is presented for in situ growth and deposition PbS nanocrystals with oleic-acid passivation. A lead precursor containing sulfur was mixed with oleic acid in toluene and processed in a supercritical fluid condition at different temperatures of 140, 270 and 330 °C for 20 min. The quantum dots were deposited on a fluorine-doped tin oxide glass substrate inside the supercritical reactor. Transmission electron microscopy, X-ray diffraction, absorption and dynamic light scattering showed that the nanocrystals processed at the supercritical condition (330 °C) are fully crystalline with a narrow size distribution of ∼3 nm with an absorption wavelength of 915 nm (bandgap of 1.3 eV). Fourier transform infrared spectroscopy indicated that the PbS quantum dots are passivated by oleic acid molecules during the growth. Photovoltaic characteristics of Schottky junction solar cells showed an improvement over devices prepared by spin-coating. - Highlights: • Supercritical fluid processing and in situ deposition of PbS QDs are presented. • The prepared nanocrystals are mono-dispersed with an optical bandgap of 1.3 eV. • Photovoltaic performance of the in situ deposited nanocrystals is reported. • An improved PV performance compared to spin coated Schottky solar cells is shown.

  13. Facile preparation of PbS nanostructures and PbS/f-CNT nanocomposites using xanthate as sulfur source: Thermal and optical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Golabi, Parisa; Akbarzadeh, Raziyeh; Dehghani, Hossein, E-mail: dehghani@kashanu.ac.ir

    2015-10-25

    PbS nanostructures with different morphologies were fabricated using a new sulfur source through a facile and low cost hydro(solvo)thermal method. The influence of different reaction factors such as sulfur source, temperature, reactant, solvent and surfactant on the size and morphology of the obtained PbS particles were investigated. Beside, a simple hydrothermal process at low temperature (60 °C) for little time (4 h), has been used for preparation of PbS nanoparticles (NPs)/functionalized multi wall carbon nanotubes (f-MWCNTs) nanocomposite. The as-prepared nanocomposite possesses excellent thermal and optical properties. Thermal stability increases by depositing PbS nanoparticles on the surface of CNT. The structure, morphology, thermal and optical properties of the as-prepared nanocompounds were studied by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy, Thermogravimetric analysis (TGA), Pl spectra and UV–Vis absorption spectra. Photoluminescence spectra of PbS NPs and nanocomposite are consist of two emission peaks which centered at around 402 and 423 nm, when excited at 350 nm. It was noteworthy that the blue luminescence intensity over PbS/f-CNT nanocomposite is very lower than that of pure PbS NPs. Remarkable blue-shift from bulk material was observed on the PbS nanoparticles using UV–Vis spectrum. Furthermore, possible growth mechanism of PbS nanostructures is presented. - Graphical abstract: PbS nanostructures with different morphologies were fabricated using xanthate as sulfide source. Also, PbS/f-CNT nanocomposites were synthesized by simple hydrothermal process at low temperature (60 °C) for little time (4 h). - Highlights: • Sodium tert-butyl xanthate was used as sulfur source for synthesis of PbS. • Pb(CH{sub 3}COO){sub 2}·3H{sub 2}O salt was used for synthesis of PbS. • PbS/CNT nanocomposite was synthesized in deionized water for 4 h at 60

  14. Probing surface states in PbS nanocrystal films using pentacene field effect transistors: controlling carrier concentration and charge transport in pentacene.

    Science.gov (United States)

    Park, Byoungnam; Whitham, Kevin; Bian, Kaifu; Lim, Yee-Fun; Hanrath, Tobias

    2014-12-21

    We used a bilayer field effect transistor (FET) consisting of a thin PbS nanocrystals (NCs) film interfaced with vacuum-deposited pentacene to probe trap states in NCs. We interpret the observed threshold voltage shift in context of charge carrier trapping by PbS NCs and relate the magnitude of the threshold voltage shift to the number of trapped carriers. We explored a series of NC surface ligands to modify the interface between PbS NCs and pentacene and demonstrate the impact of interface chemistry on charge carrier density and the FET mobility in a pentacene FET.

  15. science

    International Development Research Centre (IDRC) Digital Library (Canada)

    David Spurgeon

    Give us the tools: science and technology for development. Ottawa, ...... altered technical rela- tionships among the factors used in the process of production, and the en- .... to ourselves only the rights of audit and periodic substantive review." If a ...... and destroying scarce water reserves, recreational areas and a generally.

  16. Implementation of Multiple Intelligences Supported Project-Based Learning in EFL/ESL Classrooms

    Science.gov (United States)

    Bas, Gokhan

    2008-01-01

    This article deals with the implementation of Multiple Intelligences supported Project-Based learning in EFL/ESL Classrooms. In this study, after Multiple Intelligences supported Project-based learning was presented shortly, the implementation of this learning method into English classrooms. Implementation process of MI supported Project-based…

  17. Creating a Project-Based Learning Environment to Improve Project Management Skills of Graduate Students

    Science.gov (United States)

    Arantes do Amaral, Joao Alberto; Gonçalves, Paulo; Hess, Aurélio

    2015-01-01

    This article describes the project-based learning environment created to support project management graduate courses. The paper will focus on the learning context and procedures followed for 13 years, in 47 project-based learning MBA courses, involving approximately 1,400 students and 34 community partners.

  18. Implications of Project-Based Funding of Research on Budgeting and Financial Management in Public Universities

    Science.gov (United States)

    Raudla, Ringa; Karo, Erkki; Valdmaa, Kaija; Kattel, Rainer

    2015-01-01

    The main goal of the paper is to explore--both theoretically and empirically--the implications of project-based research funding for budgeting and financial management at public universities. The theoretical contribution of the paper is to provide a synthesized discussion of the possible impacts of project-based funding on university financial…

  19. Project-Based Learning in Post-WWII Japanese School Curriculum: An Analysis via Curriculum Orientations

    Science.gov (United States)

    Nomura, Kazuyuki

    2017-01-01

    In the 2000s, the new national curriculum, dubbed as the "yutori curriculum," introduced a new subject for project-based learning "Integrated Study" as its prominent feature. Comparing curriculum orientations in project-based learning in three historical periods after the WWII including Integrated Study, this paper aims to…

  20. Peer Feedback to Facilitate Project-Based Learning in an Online Environment

    Science.gov (United States)

    Ching, Yu-Hui; Hsu, Yu-Chang

    2013-01-01

    There has been limited research examining the pedagogical benefits of peer feedback for facilitating project-based learning in an online environment. Using a mixed method approach, this paper examines graduate students' participation and perceptions of peer feedback activity that supports project-based learning in an online instructional design…

  1. Implementing a Project-Based Learning Model in a Pre-Service Leadership Program

    Science.gov (United States)

    Albritton, Shelly; Stacks, Jamie

    2016-01-01

    This paper describes two instructors' efforts to more authentically engage students in a preservice leadership program's course called Program Planning and Evaluation by using a project-based learning approach. Markham, Larmer, and Ravitz (2003) describe project-based learning (PjBL) as "a systematic teaching method that engages students in…

  2. Students' Perceptions of Life Skill Development in Project-Based Learning Schools

    Science.gov (United States)

    Meyer, Kimberly; Wurdinger, Scott

    2016-01-01

    This research aimed to examine students' perceptions of their life skills while attending project-based learning (PBL) schools. The study focused on three questions including: (1) What are students' perceptions of their development of life skills in project-based learning schools?; (2) In what ways, if any, do students perceive an increase in…

  3. Project-Based Learning and Student Knowledge Construction during Asynchronous Online Discussion

    Science.gov (United States)

    Koh, Joyce Hwee Ling; Herring, Susan C.; Hew, Khe Foon

    2010-01-01

    Project-based learning engages students in problem solving through artefact design. However, previous studies of online project-based learning have focused primarily on the dynamics of online collaboration; students' knowledge construction throughout this process has not been examined thoroughly. This case study analyzed the relationship between…

  4. Project-Based Learning to Promote Effective Learning in Biotechnology Courses

    Directory of Open Access Journals (Sweden)

    Farahnaz Movahedzadeh

    2012-01-01

    Full Text Available With enrollment in the fields of science, technology, engineering, and mathematics (STEM shrinking, teachers are faced with the problem of appealing to a new generation of students without sacrificing educational quality. Evidence has shown that this problem can be reduced with the use of a number of pedagogical strategies of which project-based learning (PBL is one. PBL addresses the fundamental challenge of increasing students’ motivation, their mastery of course material, and finding applications for what they have learned to apply in various situations. This study demonstrates the benefits of redesigning a standard lab-based molecular biology course to create a more effective learning environment. Using PBL, students who enrolled in Bio-251 at Harold Washington College in Chicago were given the responsibility of cloning a bacterial gene from one species into a new host species. They were then tasked with the expression and purification of the resulting protein for future research purposes at University of Illinois-Chicago, a leading 4-year research institute. With use of the PBL method, students showed improvement in the areas of self-confidence, lab technical skills, and interest in STEM-related fields and, most of all, the students showed a high level of performance and satisfaction.

  5. Project-Based Learning Courses: The Relationship Between Faculty-Intended Course Implementation and Students' Perceptions

    Science.gov (United States)

    Simonovich, Jennifer A.; Towers, Emily; Zastavker, Yevgeniya V.

    2012-02-01

    Project-based learning (PjBL) has been shown to improve students' performance and satisfaction with their coursework, particularly in science and engineering courses. Specific aspects of PjBL that contribute to this improvement are student autonomy, course scaffolding, and instructor support. This study investigates two PjBL courses required for engineering majors at a small technical school, Introductory Mechanics Laboratory and Introductory Engineering Design. The three data sources used in this work are classroom observations (one laboratory and four design sessions) and semi-structured in-depth interviews with twelve students and six faculty. Grounded theory approach is used in a two-step fashion by (1) analyzing each data set individually and (2) performing full triangulation of all three data sets. In this talk, we demonstrate the relationship between faculty intentions and student perceptions regarding the three PjBL aspects -- student autonomy, course scaffolding, and instructor support -- within the context of these two courses. We further discuss implications for the course design and professional development of faculty.

  6. Range resolution and reproducibility of a dedicated phantom for proton PBS daily quality assurance.

    Science.gov (United States)

    Placidi, Lorenzo; Togno, Michele; Weber, Damien C; Lomax, Antony J; Hrbacek, Jan

    2018-03-13

    Wedge phantoms coupled with a CCD camera are suggested as a simple means to improve the efficiency of quality assurance for pencil beam scanning (PBS) proton therapy, in particular to verify energy/range consistency on a daily basis. The method is based on the analysis of an integral image created by a pencil beam (PB) pattern delivered through a wedge. We have investigated the reproducibility of this method and its dependence on setup and positional beam errors for a commercially available phantom (Sphinx ® , IBA Dosimetry) and CCD camera (Lynx ® , IBA Dosimetry) system. The phantom includes 4 wedges of different thickness, allowing verification of the range for 4 energies within one integral image. Each wedge was irradiated with a line pattern of clinical energies (120, 150, 180 and 230MeV). The equipment was aligned to the isocenter using lasers, and the delivery was repeated for 5 consecutive days, 4 times each day. Range was computed using the myQA software (IBA Dosimetry) and inter- and intra-setup uncertainty were calculated. Dependence of range on energy was investigated delivering the same pencil beam pattern but with energy variations in steps of ±0.2MeV for all the nominal energies, up to ±1.0MeV. Possible range uncertainties, caused by setup and positional errors, were then simulated including inclination of the phantom, pencil beam and couch shifts. Intra position setup (based on in-room laser system) shows a maximum in plane difference within 1.5mm. Range reproducibility (standard deviation) was less than 0.14mm. Setup and beam errors did not affect significantly the results, except for a vertical shift of 10mm which leads to an error in the range computation. Taking into account different day-to-day setup and beam errors, day-to-day determination of range has been shown to be reproducible using the proposed system. Copyright © 2018. Published by Elsevier GmbH.

  7. Experimental validation of a deforming grid 4D dose calculation for PBS proton therapy

    Science.gov (United States)

    Krieger, Miriam; Klimpki, Grischa; Fattori, Giovanni; Hrbacek, Jan; Oxley, David; Safai, Sairos; Weber, Damien C.; Lomax, Antony J.; Zhang, Ye

    2018-03-01

    The aim of this study was to verify the temporal accuracy of the estimated dose distribution by a 4D dose calculation (4DDC) in comparison to measurements. A single-field plan (0.6 Gy), optimised for a liver patient case (CTV volume: 403cc), was delivered to a homogeneous PMMA phantom and measured by a high resolution scintillating-CCD system at two water equivalent depths. Various motion scenarios (no motion and motions with amplitude of 10 mm and two periods: 3.7 s and 4.4 s) were simulated using a 4D Quasar phantom and logged by an optical tracking system in real-time. Three motion mitigation approaches (single delivery, 6× layered and volumetric rescanning) were applied, resulting in 10 individual measurements. 4D dose distributions were retrospectively calculated in water by taking into account the delivery log files (retrospective) containing information on the actually delivered spot positions, fluences, and time stamps. Moreover, in order to evaluate the sensitivity of the 4DDC inputs, the corresponding prospective 4DDCs were performed as a comparison, using the estimated time stamps of the spot delivery and repeated periodical motion patterns. 2D gamma analyses and dose-difference-histograms were used to quantify the agreement between measurements and calculations for all pixels with > 5% of the maximum calculated dose. The results show that a mean gamma score of 99.2% with standard deviation 1.0% can be achieved for 3%/3 mm criteria and all scenarios can reach a score of more than 95%. The average area with more than 5% dose difference was 6.2%. Deviations due to input uncertainties were obvious for single scan deliveries but could be smeared out once rescanning was applied. Thus, the deforming grid 4DDC has been demonstrated to be able to predict the complex patterns of 4D dose distributions for PBS proton therapy with high dosimetric and geometric accuracy, and it can be used as a valid clinical tool for 4D treatment planning, motion mitigation

  8. Effect of Maleated Compatibiliser (PBS-g-MA) Addition on the Flexural Properties and Water Absorption of Poly(butylene succinate)/ kenaf Bast Fibre Composites

    International Nuclear Information System (INIS)

    Ahmad, M.Z.T.; Mohd, Z.A.M.; Mat, R.T.; Ahmad, M.Z.T.; Mohd, Z.A.I.; Mat, R.T.; Rahim, S.

    2013-01-01

    Poly(butylene succinate) (PBS) composites with 30 wt.% loading of kenaf bast fibre (KBF) were compatibilised with 5 wt. % maleated PBS (PBS-g-MA). The maleic anhydride (MA) concentration in the compatibiliser was either 3, 5, 7 or 10 phr. In general, the compatibilised composites showed better flexural properties than the un-compatibilised composite. The highest increment in the flexural strength and modulus of 12.7 and 8.9 %, respectively, were obtained with the addition of PBS-g-MA with MA concentration of 5 phr. Compatibilised and un-compatibilised PBS/ KBF composites were immersed in distilled water for 90 days. The absorption of water by all the composites was observed to follow Ficks law. The equilibrium moisture content, M m , of the composites with PBS-g-MA at 3, 5 and 7 phr of MA concentrations was lower than that of the un-compatibilised composite due to improved fiber-matrix interfacial adhesion and reduction of voids content. Both un-compatibilised and compatibilised composites showed dimensional instability after the water absorption. This was probably due to the degradation of the fibre-matrix interfacial adhesion and fibre integrity. The flexural properties of these composites decreased after the water absorption. After re-drying only some of the flexural properties were recovered from plasticizing effect of water. (author)

  9. A project-based geoscience curriculum: select examples

    Science.gov (United States)

    Brown, L. M.; Kelso, P. R.; White, R. J.; Rexroad, C. B.

    2007-12-01

    Principles of constructivist educational philosophy serve as a foundation for the recently completed National Science Foundation sponsored undergraduate curricular revision undertaken by the Geology Department of Lake Superior State University. We integrate lecture and laboratory sessions utilizing active learning strategies that focus on real-world geoscience experiences and problems. In this presentation, we discuss details of three research-like projects that require students to access original data, process and model the data using appropriate geological software, interpret and defend results, and disseminate results in reports, posters, and class presentations. The projects are from three upper division courses, Carbonate Systems, Sequence Stratigraphy, and Geophysical Systems, where teams of two to four students are presented with defined problems of durations ranging from a few weeks to an entire semester. Project goals and location, some background information, and specified dates and expectations for interim and final written and oral reports are provided to students. Some projects require the entire class to work on one data set, some require each team to be initially responsible for a portion of the project with teams ultimately merging data for interpretation and to arrive at final conclusions. Some projects require students to utilize data from appropriate geological web sites such as state geological surveys. Others require students to design surveys and utilize appropriate instruments of their choice for field data collection. Students learn usage and applications of appropriate geological software in compiling, processing, modeling, and interpreting data and preparing formal reports and presentations. Students uniformly report heightened interest and motivation when engaged in these projects. Our new curriculum has resulted in an increase in students" quantitative and interpretive skills along with dramatic improvement in communication and

  10. SU-F-T-185: Study of the Robustness of a Proton Arc Technique Based On PBS Beams

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Z [Reading Hospital, West Reading, PA (United States); Zheng, Y [Procure Proton Therapy Center, Oklahoma City, OK (United States)

    2016-06-15

    Purpose: One potential technique to realize proton arc is through using PBS beams from many directions to form overlaid Bragg peak (OBP) spots and placing these OBP spots throughout the target volume to achieve desired dose distribution. In this study, we analyzed the robustness of this proton arc technique. Methods: We used a cylindrical water phantom of 20 cm in radius in our robustness analysis. To study the range uncertainty effect, we changed the density of the phantom by ±3%. To study the setup uncertainty effect, we shifted the phantom by 3 & 5 mm. We also combined the range and setup uncertainties (3mm/±3%). For each test plan, we performed dose calculation for the nominal and 6 disturbed scenarios. Two test plans were used, one with single OBP spot and the other consisting of 121 OBP spots covering a 10×10cm{sup 2} area. We compared the dose profiles between the nominal and disturbed scenarios to estimate the impact of the uncertainties. Dose calculation was performed with Gate/GEANT based Monte Carlo software in cloud computing environment. Results: For each of the 7 scenarios, we simulated 100k & 10M events for plans consisting of single OBP spot and 121 OBP spots respectively. For single OBP spot, the setup uncertainty had minimum impact on the spot’s dose profile while range uncertainty had significant impact on the dose profile. For plan consisting of 121 OBP spots, similar effect was observed but the extent of disturbance was much less compared to single OBP spot. Conclusion: For PBS arc technique, range uncertainty has significantly more impact than setup uncertainty. Although single OBP spot can be severely disturbed by the range uncertainty, the overall effect is much less when a large number of OBP spots are used. Robustness optimization for PBS arc technique should consider range uncertainty with priority.

  11. Ultra high pressure homogenization (UHPH) inactivation of Bacillus amyloliquefaciens spores in phosphate buffered saline (PBS) and milk

    Science.gov (United States)

    Dong, Peng; Georget, Erika S.; Aganovic, Kemal; Heinz, Volker; Mathys, Alexander

    2015-01-01

    Ultra high pressure homogenization (UHPH) opens up new areas for dynamic high pressure assisted thermal sterilization of liquids. Bacillus amyloliquefaciens spores are resistant to high isostatic pressure and temperature and were suggested as potential surrogate for high pressure thermal sterilization validation. B. amyloliquefaciens spores suspended in PBS buffer (0.01 M, pH 7.0), low fat milk (1.5%, pH 6.7), and whole milk (3.5%, pH 6.7) at initial concentration of ~106 CFU/mL were subjected to UHPH treatments at 200, 300, and 350 MPa with an inlet temperature at ~80°C. Thermal inactivation kinetics of B. amyloliquefaciens spores in PBS and milk were assessed with thin wall glass capillaries and modeled using first-order and Weibull models. The residence time during UHPH treatments was estimated to determine the contribution of temperature to spore inactivation by UHPH. No sublethal injury was detected after UHPH treatments using sodium chloride as selective component in the nutrient agar medium. The inactivation profiles of spores in PBS buffer and milk were compared and fat provided no clear protective effect for spores against treatments. Treatment at 200 MPa with valve temperatures lower than 125°C caused no reduction of spores. A reduction of 3.5 log10CFU/mL of B. amyloliquefaciens spores was achieved by treatment at 350 MPa with a valve temperature higher than 150°C. The modeled thermal inactivation and observed inactivation during UHPH treatments suggest that temperature could be the main lethal effect driving inactivation. PMID:26236296

  12. SU-F-T-185: Study of the Robustness of a Proton Arc Technique Based On PBS Beams

    International Nuclear Information System (INIS)

    Wang, Z; Zheng, Y

    2016-01-01

    Purpose: One potential technique to realize proton arc is through using PBS beams from many directions to form overlaid Bragg peak (OBP) spots and placing these OBP spots throughout the target volume to achieve desired dose distribution. In this study, we analyzed the robustness of this proton arc technique. Methods: We used a cylindrical water phantom of 20 cm in radius in our robustness analysis. To study the range uncertainty effect, we changed the density of the phantom by ±3%. To study the setup uncertainty effect, we shifted the phantom by 3 & 5 mm. We also combined the range and setup uncertainties (3mm/±3%). For each test plan, we performed dose calculation for the nominal and 6 disturbed scenarios. Two test plans were used, one with single OBP spot and the other consisting of 121 OBP spots covering a 10×10cm"2 area. We compared the dose profiles between the nominal and disturbed scenarios to estimate the impact of the uncertainties. Dose calculation was performed with Gate/GEANT based Monte Carlo software in cloud computing environment. Results: For each of the 7 scenarios, we simulated 100k & 10M events for plans consisting of single OBP spot and 121 OBP spots respectively. For single OBP spot, the setup uncertainty had minimum impact on the spot’s dose profile while range uncertainty had significant impact on the dose profile. For plan consisting of 121 OBP spots, similar effect was observed but the extent of disturbance was much less compared to single OBP spot. Conclusion: For PBS arc technique, range uncertainty has significantly more impact than setup uncertainty. Although single OBP spot can be severely disturbed by the range uncertainty, the overall effect is much less when a large number of OBP spots are used. Robustness optimization for PBS arc technique should consider range uncertainty with priority.

  13. SU-E-T-262: Planning for Proton Pencil Beam Scanning (PBS): Applications of Gradient Optimization for Field Matching

    Energy Technology Data Exchange (ETDEWEB)

    Lin, H; Kirk, M; Zhai, H; Ding, X; Liu, H; Hill-Kayser, C; Lustig, R; Tochner, Z; Deville, C; Vapiwala, N; McDonough, J; Both, S [University Pennsylvania, Philadelphia, PA (United States)

    2014-06-01

    Purpose: To propose the gradient optimization(GO) approach in planning for matching proton PBS fields and present two commonly used applications in our institution. Methods: GO is employed for PBS field matching in the scenarios that when the size of the target is beyond the field size limit of the beam delivery system or matching is required for beams from different angles to either improve the sparing of important organs or to pass through a short and simple beam path. Overlap is designed between adjacent fields and in the overlapped junction, the dose was optimized such that it gradually decreases in one field and the decrease is compensated by increase from another field. Clinical applications of this approach on craniospinal irradiation(CSI) and whole pelvis treatment were presented. Mathematical model was developed to study the relationships between dose errors, setup errors and junction lengths. Results: Uniform and conformal dose coverage to the entire target volumes was achieved for both applications using GO approach. For CSI, the gradient matching (6.7cm junction) between fields overcame the complexity of planning associated with feathering match lines. A slow dose gradient in the junction area significantly reduced the sensitivity of the treatment to setup errors. For whole pelvis, gradient matching (4cm junction) between posterior fields for superior target and bilateral fields for inferior target provided dose sparing to organs such as bowel, bladder and rectum. For a setup error of 3 mm in longitudinal direction from one field, mathematical model predicted dose errors of 10%, 6% and 4.3% for junction length of 3, 5 and 7cm. Conclusion: This GO approach improves the quality of the PBS treatment plan with matching fields while maintaining the safety of treatment delivery relative to potential misalignments.

  14. SU-E-T-262: Planning for Proton Pencil Beam Scanning (PBS): Applications of Gradient Optimization for Field Matching

    International Nuclear Information System (INIS)

    Lin, H; Kirk, M; Zhai, H; Ding, X; Liu, H; Hill-Kayser, C; Lustig, R; Tochner, Z; Deville, C; Vapiwala, N; McDonough, J; Both, S

    2014-01-01

    Purpose: To propose the gradient optimization(GO) approach in planning for matching proton PBS fields and present two commonly used applications in our institution. Methods: GO is employed for PBS field matching in the scenarios that when the size of the target is beyond the field size limit of the beam delivery system or matching is required for beams from different angles to either improve the sparing of important organs or to pass through a short and simple beam path. Overlap is designed between adjacent fields and in the overlapped junction, the dose was optimized such that it gradually decreases in one field and the decrease is compensated by increase from another field. Clinical applications of this approach on craniospinal irradiation(CSI) and whole pelvis treatment were presented. Mathematical model was developed to study the relationships between dose errors, setup errors and junction lengths. Results: Uniform and conformal dose coverage to the entire target volumes was achieved for both applications using GO approach. For CSI, the gradient matching (6.7cm junction) between fields overcame the complexity of planning associated with feathering match lines. A slow dose gradient in the junction area significantly reduced the sensitivity of the treatment to setup errors. For whole pelvis, gradient matching (4cm junction) between posterior fields for superior target and bilateral fields for inferior target provided dose sparing to organs such as bowel, bladder and rectum. For a setup error of 3 mm in longitudinal direction from one field, mathematical model predicted dose errors of 10%, 6% and 4.3% for junction length of 3, 5 and 7cm. Conclusion: This GO approach improves the quality of the PBS treatment plan with matching fields while maintaining the safety of treatment delivery relative to potential misalignments

  15. Study of band gap and determination of size of PbS quantum dots synthesized by colloidal solution

    Directory of Open Access Journals (Sweden)

    M. S. Ghamsari

    2005-03-01

    Full Text Available   PbS semiconductor non-crystals have been synthesized in order to study the modification of their electronic structures and optical properties in relation to their size. The synthesis has been carried out by using the techniques of colloidal chemistry. Strong quantum confinement behavior has been observed based on the analysis of optical spectra of these particles. The average particle size approximated by x-ray line width and hyperbolic band model calculation. Heterogeneous broadening of optical spectrum is studied finally.

  16. Teaching with Soap: Examples of Project-Based Units for Students and Future Educators

    Science.gov (United States)

    Farrell, Ivan; Hamed, Kastro M.

    2016-01-01

    This article describes the use of project-based instruction in activities and labs intended to develop higher-order thinking skills with high school students and pre-service teachers through the use of soap making.

  17. Toward Project-based Learning and Team Formation in Open Learning Environments

    NARCIS (Netherlands)

    Spoelstra, Howard; Van Rosmalen, Peter; Sloep, Peter

    2014-01-01

    Open Learning Environments, MOOCs, as well as Social Learning Networks, embody a new approach to learning. Although both emphasise interactive participation, somewhat surprisingly, they do not readily support bond creating and motivating collaborative learning opportunities. Providing project-based

  18. PERLUASAN IMPLEMENTASI PENDIDIKAN KEWIRAUSAHAAN MODEL PROJECT BASED LEARNING BAGI REMAJA PUTUS SEKOLAH KORBAN GEMPA

    Directory of Open Access Journals (Sweden)

    Moerdiyanto Moerdiyanto

    2012-04-01

    Full Text Available Abstract: Widen Implementation of Entrepreneurship Education Using Project Based Learning Model for Earthquake Victim Drop Out Teenagers. This action research aims at figuring out achievement level of entrepreneurship personalities mastering and business skills held by drop out teenagers after taking part in real business learning experience using Project Based Learning. The population for this study is all of the earthquake victim drop out teenagers in Piyungan, Pleret, and Sewon Bantul Yogyakarta Special Territory.  Interviewed, questionnaire, observation, and documentation are employed to collect data. The results show that entrepreneurship education using Project Based Learning model leads to highly mastering of entrepreneurship personalities (soft skill and highly mastering of business skills (hard skill. Furthermore, through this study Kelompok Usaha Mandiri (Group of Independent Business is created, and then the drop out teenagers can run their own business.   Keyword: business skill, project based learning, soft skill, hard skill   Abstrak: Perluasan Implementasi Pendidikan Kewirausahaan Model Project Based Learning Bagi Remaja Putus Sekolah Korban Gempa. Penelitian ini merupakan penelitian tindakan dengan tujuan untuk mengetahui tingkat keberhasilan penguasaan kepribadian (jiwa kewirausahaan dan keterampilan usaha yang dimiliki Remaja Putus Sekolah (RPS setelah memperoleh pengalaman belajar bisnis riil dengan model Project Based Learning. Populasi dalam penelitian ini adalah semua remaja putus sekolah korban gempa di Kecamatan Piyungan, Kecamatan Pleret, dan Kecamatan Sewon Kabupaten Bantul DIY. Teknik pengumpulan data menggunakan wawancara, angket, observasi, dokumentasi, dan pemberian tugas. Data dianalisis menggunakan teknik deskriptif kuantitatif dan kualitatif. Hasil penelitian menunjukkan bahwa pemberian pendidikan kewirausahaan dengan menggunakan model Project Based Learning bisa berhasil dengan baik yang ditunjukkan dengan

  19. ICT support for students’ collaboration in problem and project based learning

    DEFF Research Database (Denmark)

    Rongbutsri, Nikorn; Khalid, Md. Saifuddin; Ryberg, Thomas

    2011-01-01

    This paper reports and analyses quantitative and qualitative data from a study, which seeks a better understanding of how students use various technologies to support their project collaboration activities in a problem and project based learning environment. More generally the aim of the study......, and the present paper, is to shed light on students’ technology practices within higher education – particularly in relation to problem and project based learning....

  20. Project-Based Learning in a STEM Academy: Student Engagement and Interest in STEM Careers

    Science.gov (United States)

    Misher, Pamela Henry

    This case study explored the utilization of project-based learning (PBL) and how it affected student engagement and interest in STEM careers. Sixty-seven students and nine teachers participated in this case study. Three research questions addressed student engagement, perceptions, and challenges during PBL implementation. This study was designed to understand the experiences teachers and students had when they participated in a PBL environment. This research investigated how to develop a globally skilled workforce utilizing a PBL approach and the challenges teachers encountered during implementation. The survey data and informal focus-group sessions with staff and students were utilized, analyzed, and summarized in order to obtain insight on perceptions, challenges, and implementation of PBL. PBL is an instructional approach that was designed to encourage more engaged learning. This approach was built upon realistic learning activities that stimulated student interest and motivation. This research discovered that PBL did teach content and 21st century skills as students worked collaboratively toward a common goal while responding to a question or problem. This study revealed that rigorous projects were carefully planned to aid students in learning important academic content. This study displayed how PBL allowed students to reflect on their projects and ideas with the opportunity to voice their decisions and findings. This instructional approach provided opportunities for students to investigate and strengthen interest in future STEM careers. The driving force of America's future economy and maintaining the competitive edge will be through more innovation, mainly derived from advances in STEM (Science, Technology, Engineering, and Math) careers. As business and industry leaders stressed the importance of improving STEM education, there continued to be a need to better prepare students to fill STEM-related careers. This research adds to the current body of research

  1. The role of cationic precursors in structural, morphological and optical properties of PbS thin films

    International Nuclear Information System (INIS)

    Preetha, K C; Murali, K V; Ragina, A J; Deepa, K; Dhanya, A C; Remadevi, T L

    2013-01-01

    Thin films of Lead sulphide (PbS) were grown on soda lime glass substrate by Successive Ionic Layer Adsorption and Reaction (SILAR) method using lead acetate, lead chloride, lead nitrate, and lead sulphate as cationic precursors and thioacetamide as sulphur source. The experiments were carried out at room temperature under normal pressure utilizing aqueous conditions. The structural and morphological aspects of the as prepared samples were investigated by means of XRD and SEM results. The prepared samples were polycrystalline with nanometer-sized grains and identified as galena type cubic structure (FCC). The values of average crystallite size were found to be in the range 22 to 30 nm. The SEM micrographs show variations in morphology. Optical studies revealed that the absorption edges of the films indicated strong blue shifts with respect to bulk sample. In this work, we establish that the cationic precursor sources and in turn the size of the crystallites affects the structural, morphological and optical properties of PbS thin films.

  2. Photoelectron emission as a tool to assess dose of electron radiation received by ZrO2:PbS films

    International Nuclear Information System (INIS)

    Krumpane, Diana; Dekhtyar, Yury; Surkova, Indra; Romanova, Marina

    2013-01-01

    PbS nano dots embedded in ZrO 2 thin film matrix (ZrO 2 :PbS films) were studied for application in nanodosimetry of electron radiation used in radiation therapy. ZrO 2 :PbS films were irradiated with 9 MeV electron radiation with doses 3, 7 and 10 Gy using medical linear accelerator. Detection of the dosimetric signal was made by measuring and comparing photoelectron emission current from ZrO 2 :PbS films before and after irradiation. It was found that electron radiation decreased intensity of photoemission current from the films. Derivatives of the photoemission spectra were calculated and maximums at photon energies 5.65 and 5.75 eV were observed. Amplitude of these maximums decreased after irradiation with electrons. Good linear correlation was found between the relative decrease of the intensity of these maximums and dose of electron radiation. Observed changes in photoemission spectra from ZrO 2 :PbS films under influence of electron radiation suggested that the films may be considered to be effective material for electron radiation dosimetry. Photoelectron emission is a tool that allows to read the signal from such dosimeter. (authors)

  3. Knowledge collaborative incentive based on inter-organizational cooperative innovation of project-based supply chain

    Directory of Open Access Journals (Sweden)

    Guangdong Wu

    2013-09-01

    Full Text Available Purpose: Within project-based supply chain inter-organizational cooperative innovation, the achievement of project value-adding reflects by factors such as project-based organizational effect level, the relationship between project cooperative innovation objectives etc. The purpose is to provide a reliable reference for the contractor reasonably allocate the effect level and resources between the knowledge input and innovation stage and realize the knowledge collaboration for project-based supply chain. Design/methodology/approach: Based on the assumption of equal cooperation between project-based organizations, from the view of maximizing project value-adding and the relationship of effect cost between knowledge input and innovation stage in consideration, the knowledge collaborative incentive model for project-based supply chain inter-organizational cooperative innovation was established, and solved through the first-order and second-order approach, then the digital simulation and example analysis were presented. Findings: The results show that, the project management enterprise resorted to adjust project knowledge collaboration incentive intensity and implemented knowledge input-innovation coordinative incentive strategy, not only could achieve project value-adding maximization, but also could realize net earnings Pareto improvement between project management enterprise and contractor. Research limitations/implications: To simplify the knowledge flow among project-based organizations, the knowledge flow in the model hypothesis is presented as knowledge input and knowledge innovation stage, thus it may affect the final analysis results. Originality/value: In construction project practice, knowledge is become more and more important to achieve project value-adding. The research can provide a theoretical guideline for the project-based organizations, such as the contractor, the owner, especially how to utilize their core knowledge.

  4. Structural, optical and electrical characterization of Mn2+ and Cd2+ doped/co-doped PbS nanocrystals

    International Nuclear Information System (INIS)

    Sakthi Sudar Saravanan, R.; Meena, M.; Pukazhselvan, D.; Mahadevan, C.K.

    2015-01-01

    Highlights: • Mn and Cd doped/codoped nano PbS was synthesized by SMI method. • The observed stress is ∼90% lower, and the strain is only in the order of 10 −6 . • Band gap value can be enhanced from 0.5 eV to 2.025–2.235 eV (±0.012 eV). • Role of two conduction activation barriers was observed. - Abstract: The strain and stress minimized nanoparticles of PbS, Pb 0.95 Mn 0.05 S, Pb 0.95 Cd 0.05 S and Pb 0.90 Mn 0.05 Cd 0.05 S were successfully synthesized using solvothermal microwave irradiation (SMI) method. The quality/performance of the materials was found to be in the series Pb 0.90 Mn 0.05 Cd 0.05 S > Pb 0.95 Cd 0.05 S > Pb 0.95 Mn 0.05 S > PbS. The average crystallite size in the best material Pb 0.90 Mn 0.05 Cd 0.05 S was found to be ∼18 nm where the particles are distributed within the range 20–60 nm. Optical studies reveals the existence of direct band gap in the range of 2.025–2.235 eV (±0.012 eV). This is one of the widest E g values reported for this system. Electrical measurements were performed on compacts of nanoparticles in the temperature range 313–433 K and frequency range 100 Hz–1 MHz. The conductivity profile exhibits two components; in which the activation energy (ΔE) values obtained for the temperature range 373–433 K is almost twice as compared to the ΔE value obtained for 313–373 K. Nonetheless, the conductivity at the higher temperatures was always higher than at the low temperatures and interestingly, the nanoparticles exhibits higher conductivity than their bulk counterpart. The feasible mechanism of conduction is discussed

  5. Synthesis of single-crystal PbS nanorods via a simple hydrothermal process using PEO-PPO-PEO triblock copolymer as a structure-directing agent

    International Nuclear Information System (INIS)

    Bu Junfu; Nie Chageng; Liang Jinxia; Sun Lan; Xie Zhaoxiong; Wu Qi; Lin Changjian

    2011-01-01

    Single-crystal PbS nanorods were successfully synthesized through a simple hydrothermal route using PEO-PPO-PEO triblock copolymer (P123) as a structure-directing agent. The XRD pattern indicates that the crystal structure of the nanorods is face-centre-cubic rocksalt. A SEM image shows that the nanorods have a diameter of 40-70 nm and a length of 200-600 nm, and both tips exhibit taper-like structures. HRTEM and SAED images reveal the single-crystalline nature of the nanorods with the growth along the (111) direction. The experimental results indicated that the P123 concentration and reaction temperature played important roles in controlling the morphology of the PbS nanostructures. The optical property of PbS nanorods was investigated by UV-Vis absorption spectroscopy and the band structure was calculated by the B3LYP hybrid density functional theory.

  6. Decoration of PbS nanoparticles on Al-doped ZnO nanorod array thin film with hydrogen treatment as a photoelectrode for solar water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Chih-Hsiung; Chen, Chao-Hong [Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Chen, Dong-Hwang, E-mail: chendh@mail.ncku.edu.tw [Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)

    2013-03-25

    Highlights: ► AZO nanorod array thin film is used as a photoanode for solar water splitting. ► Hydrogen treatment and sensitization by PbS nanoparticles enhance photocurrent. ► A novel ITO/FTO-free composite photoelectrode is developed. ► The pre-fabrication and use of an extra TCO thin film substrate is unnecessary. -- Abstract: Al-doped ZnO (AZO) nanorod arrays thin film with hydrogen treatment is directly used as a photoelectrode for solar water splitting without an extra transparent conducting oxide (TCO) thin film because it possesses the functions of TCO thin film and photoactive 1-dimensional nanostructured semiconductor simultaneously. To enhance the absorption in the visible region, PbS nanoparticles decorated the AZO nanorods via successive ionic layer adsorption and reaction route. The PbS nanoparticles have a face-centered cubic structure and their decoration does not destroy the 1-dimensional morphology of AZO nanorod arrays. With increasing the cycle number of PbS nanoparticles decoration, the grain size and loading of PbS nanoparticles become larger gradually which leads to lower energy bandgap and stronger absorption. A maximum photocurrent density of 1.65 mW cm{sup −2} is obtained when the cycle number is 20, which is much higher than those without PbS nanoparticles sensitization or hydrogen treatment. This demonstrates that the AZO nanorod array thin film with hydrogen treatment can be directly used as a photoelectrode without an extra TCO thin film. Because the use of expensive metals can be avoided and the pre-fabrication of TCO thin film substrate is necessary no more, the fabrication of such a composite photoelectrode becomes simple and low-cost. So, it has great potentials in solar water splitting after sensitization by quantum dots capable of visible light absorption.

  7. Ultrafast exciton decay in PbS quantum dots through simultaneous electron and hole recombination with a surface-localized ion pair

    Energy Technology Data Exchange (ETDEWEB)

    Edme, Kedy; Bettis Homan, Stephanie; Nepomnyashchii, Alexander B.; Weiss, Emily A., E-mail: e-weiss@northwestern.edu

    2016-06-01

    Highlights: • We synthesize complexes of PbS quantum dots (QDs) and tetracyanoquinodimethane (TCNQ). Each PbS QD spontaneously reduces up to 17 TCNQ molecules. • The photoluminescence of the PbS QDs is quenched in the presence of the reduced TCNQ species through ultrafast non-radiative, simultaneous decay of the electron and hole. • We assign this decay to a four-carrier, concerted charge recombination mechanism with the surface localized sulfur–TCNQ{sup x−} ion pair. - Abstract: This paper describes the ultrafast decay of the band-edge exciton in PbS quantum dots (QDs) through simultaneous recombination of the excitonic hole and electron with the surface localized ion pair formed upon adsorption of tetracyanoquinodimethane (TCNQ). Each PbS QD (R = 1.8 nm) spontaneously reduces up to 17 TCNQ molecules upon adsorption of the TCNQ molecule to a sulfur on the QD surface. The photoluminescence of the PbS QDs is quenched in the presence of the reduced TCNQ species through ultrafast (⩽15-ps) non-radiative decay of the exciton; the rate constant for the decay process increases approximately linearly with the number of adsorbed, reduced TCNQ molecules. Near-infrared and mid-infrared transient absorption show that this decay occurs through simultaneous transfer of the excitonic electron and hole, and is assigned to a four-carrier, concerted charge recombination mechanism based on the observations that (i) the PL of the QDs recovers when spontaneously reduced TCNQ{sup 1−} desorbs from the QD surface upon addition of salt, and (ii) the PL of the QDs is preserved when another spontaneous oxidant, ferrocinium, which cannot participate in charge transfer in its reduced state, is substituted for TCNQ.

  8. Toward High-Performance Coatings for Biomedical Devices: Study on Plasma-Deposited Fluorocarbon Films and Ageing in PBS

    Directory of Open Access Journals (Sweden)

    Diego Mantovani

    2010-03-01

    Full Text Available High performance coatings tailored to medical devices represent a recognised approach to modulate surface properties. Plasma-deposited fluorocarbon films have been proposed as a potential stent coating. Previous studies have shown promising adhesion properties: the 35 nm-thick film sustained plastic deformation up to 25% such as induced during the clinical implantation. In this study, the compositional and morphological changes of plasma-deposited fluorocarbon films were examined during ageing in a pseudo-physiological medium, a phosphate buffer solution (PBS, by angle-resolved XPS, FT-IR data and AFM images. The evolution of the ageing process is discussed: defluorination and crosslinking yielded an oxidized protective top layer onto the films, which showed further degradation.

  9. Design of a QA method to characterize submillimeter-sized PBS beam properties using a 2D ionization chamber array

    Science.gov (United States)

    Lin, Yuting; Bentefour, Hassan; Flanz, Jacob; Kooy, Hanne; Clasie, Benjamin

    2018-05-01

    Pencil beam scanning (PBS) periodic quality assurance (QA) programs ensure the beam delivered to patients is within technical specifications. Two critical specifications for PBS delivery are the beam width and position. The aim of this study is to investigate whether a 2D ionization chamber array, such as the MatriXX detector (IBA Dosimetry, Schwarzenbruck, Germany), can be used to characterize submillimeter-sized PBS beam properties. The motivation is to use standard equipment, which may have pixel spacing coarser than the pencil beam size, and simplify QA workflow. The MatriXX pixels are cylindrical in shape with 4.5 mm diameter and are spaced 7.62 mm from center to center. Two major effects limit the ability of using the MatriXX to measure the spot position and width accurately. The first effect is that too few pixels sample the Gaussian shaped pencil beam profile and the second effect is volume averaging of the Gaussian profile over the pixel sensitive volumes. We designed a method that overcomes both limitations and hence enables the use of the MatriXX to characterize sub-millimeter-sized PBS beam properties. This method uses a cross-like irradiation pattern that is designed to increase the number of sampling data points and a modified Gaussian fitting technique to correct for volume averaging effects. Detector signals were calculated in this study and random noise and setup errors were added to simulate measured data. With the techniques developed in this work, the MatriXX detector can be used to characterize the position and width of sub-millimeter, σ  =  0.7 mm, sized pencil beams with uncertainty better than 3% relative to σ. With the irradiation only covering 60% of the MatriXX, the position and width of σ  =  0.9 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. If one were to not use a cross-like irradiation pattern, then the position and width of σ  =  3.6 mm sized pencil beams

  10. Silica coating of PbS quantum dots and their position control using a nanohole on Si substrate

    Science.gov (United States)

    Mukai, Kohki; Okumura, Isao; Nishizaki, Yuta; Yamashita, Shuzo; Niwa, Keisuke

    2018-04-01

    We succeeded in controlling the apparent size of a colloidal PbS quantum dot (QD) in the range of 20 to 140 nm by coating with silica and trapping the coated QDs in a nanohole prepared by scanning probe microscope lithography. Photoluminescence intensity was improved by controlling the process of adding the silica source material of tetraethoxysilane for the coating. Nanoholes of different sizes were formed on a single substrate by scanning probe oxidation with the combination of SF6 dry etching and KOH wet etching. QDs having an arbitrary energy structure can be arranged at an arbitrary position on the semiconductor substrate using this technique, which will aid in the fabrication of future nanosize solid devices such as quantum information circuits.

  11. Oscillator strength and quantum-confined Stark effect of excitons in a thin PbS quantum disk

    Science.gov (United States)

    Oukerroum, A.; El-Yadri, M.; El Aouami, A.; Feddi, E.; Dujardin, F.; Duque, C. A.; Sadoqi, M.; Long, G.

    2018-01-01

    In this paper, we report a study of the effect of a lateral electric field on a quantum-confined exciton in a thin PbS quantum disk. Our approach was performed in the framework of the effective mass theory and adiabatic approximation. The ground state energy and the stark shift were determined by using a variational method with an adequate trial wavefunction, by investigating a 2D oscillator strength under simultaneous consideration of the geometrical confinement and the electric field strength. Our results showed a strong dependence of the exciton binding and the Stark shift on the disk dimensions in both axial and longitudinal directions. On the other hand, our results also showed that the Stark shift’s dependence on the electric field is not purely quadratic but the linear contribution is also important and cannot be neglected, especially when the confinement gets weaker.

  12. Influence of grain size on structural and optic properties of PbS thin films produced by SILAR method

    International Nuclear Information System (INIS)

    Güneri, E.; Göde, F.; Çevik, S.

    2015-01-01

    In this the paper, we use the successive ion layer adsorption and reaction technique (SILAR) chemical deposition method to fabricate good quality PbS thin films and the effects of grain size on the structural and optical properties of the thin films were determined by varying deposition cases. All of the films obtained in different dipping cycles show cubic rock-salt (NaCl) structure. The preferred orientation changed from the (111) direction to the (200) direction with increasing dipping cycles. Grain size determined from scanning electron microscopy (SEM) increased from 32 nm to 104 nm. Moreover, changing of atomic ratio of the thin films is determined according to the results of energy dispersive X-ray (EDX). The transmission of the thin films was characterized by UV–Vis measurements from 400 nm to 1100 nm. It was determined from the allowed direct graphics that the energy band gaps of the thin films shift from 1.33 eV to 1.92 eV in connection with deposition conditions. The variation in band gap may be attributed to the variation of grain size. Additionally, the refractive index (n), extinction coefficient (k), real (ε 1 ) and imaginary (ε 2 ) dielectric constants varied with increasing immersion cycles. - Highlights: • The effects of grain size on the structural, optical properties of PbS thin films deposited by SILAR were investigated. • The preferred orientation varied from the (111) direction to the (200) direction with changing grain size. • The energy band gaps of the thin films shift from 1.33 eV to 1.92 eV in connection with deposition conditions. • The refractive index, extinction coefficient, real and imaginary dielectric constants varied with increasing dipping cycles

  13. Influence of grain size on structural and optic properties of PbS thin films produced by SILAR method

    Energy Technology Data Exchange (ETDEWEB)

    Güneri, E., E-mail: emineg7@gmail.com [Department of Primary Education, Erciyes University, Kayseri 38039, Turkey. (Turkey); Göde, F.; Çevik, S. [Department of Physics, Mehmet Akif Ersoy University, Burdur 15030, Turkey. (Turkey)

    2015-08-31

    In this the paper, we use the successive ion layer adsorption and reaction technique (SILAR) chemical deposition method to fabricate good quality PbS thin films and the effects of grain size on the structural and optical properties of the thin films were determined by varying deposition cases. All of the films obtained in different dipping cycles show cubic rock-salt (NaCl) structure. The preferred orientation changed from the (111) direction to the (200) direction with increasing dipping cycles. Grain size determined from scanning electron microscopy (SEM) increased from 32 nm to 104 nm. Moreover, changing of atomic ratio of the thin films is determined according to the results of energy dispersive X-ray (EDX). The transmission of the thin films was characterized by UV–Vis measurements from 400 nm to 1100 nm. It was determined from the allowed direct graphics that the energy band gaps of the thin films shift from 1.33 eV to 1.92 eV in connection with deposition conditions. The variation in band gap may be attributed to the variation of grain size. Additionally, the refractive index (n), extinction coefficient (k), real (ε{sub 1}) and imaginary (ε{sub 2}) dielectric constants varied with increasing immersion cycles. - Highlights: • The effects of grain size on the structural, optical properties of PbS thin films deposited by SILAR were investigated. • The preferred orientation varied from the (111) direction to the (200) direction with changing grain size. • The energy band gaps of the thin films shift from 1.33 eV to 1.92 eV in connection with deposition conditions. • The refractive index, extinction coefficient, real and imaginary dielectric constants varied with increasing dipping cycles.

  14. Enhancement of students’ creative thinking skills on mixture separation topic using project based student worksheet

    Science.gov (United States)

    Nurisalfah, R.; Fadiawati, N.; Jalmo, T.

    2018-05-01

    The aim of this study is to describe the effectiveness of project based student worksheet in improving students' creative thinking skills. The research method is using quasi experiment with the matching only pre-test post-test control group design. The population in this research is all students of class VII SMP N 2 Belitang Madang Raya with class VII1 as control class and class VII4 as experiment class. The sample of this research is obtaining by purposive sampling technique. The effectiveness of project based student worksheet is based on significant post-test differences between the control class and the experiment class as well as the effect size. The results show that the using of project based student worksheet is effective in improving students' creative thinking skills on mixture separation topic.

  15. THE PROJECT-BASED CURRICULUM AND COMPLEXITY IN SCHOOL: POSSIBILITIES FOR AN EDUCATION ON VALUES

    Directory of Open Access Journals (Sweden)

    Ricardo Fernandes Pátaro

    2013-07-01

    Full Text Available This paper is derived from a dissertation and the main goal is to argue how the project-based curriculum, in a perspective of complexity, can offers some possibilities for an education on values introducing studies of nowadays social problems into the school. To achieve the objectives was considered a project developed with a ten years old students. The investigation was based on project activities and daily field. As a result we have demonstrated the project-based curriculum – using the complexity, interdisciplinary and transversality as references – can help school to combine the disciplinary knowledge to the ethical formation. The investigation has show that the project-based curriculum may lead schools to succeed in implementing an education in values, pointing out some directions to develop citizens who can deal with diversity and conflicts as well as capable of get indignant with the injustices and have disposal to individual and collective welfare.

  16. Increasing EFL Learners’ Oral Production at a Public School Through Project-Based Learning

    Directory of Open Access Journals (Sweden)

    Ady Marcela Vaca Torres

    2017-07-01

    Full Text Available This research study examined how a group of ninth graders enhanced the speaking skill in an English as a foreign language classroom through project-based learning. Data about the experience were collected through field notes, transcripts of learners’ oral performance, and one interview. Grounded theory was implemented for data analysis, out of which three main findings emerged: (1 project-based learning encouraged students to increase oral production through lexical competence development, (2 helped them to overcome fears of speaking in L2, and (3, increased their interest in learning about their school life and community.

  17. PENGARUH PROJECT BASED LEARNING TERHADAP KETERAMPILAN PROSES SAINS SISWA KELAS X SMA NEGERI SIDOARJO

    Directory of Open Access Journals (Sweden)

    Nuril Maghfiroh

    2016-08-01

    Tujuan penelitian ini adalah untuk mengetahui pengaruh pembelajaran Project Based Learning terhadap keterampilan proses sains siswa kelas X SMA Negeri 4 Sidoarjo. Penelitian ini menggunakan metode Quasi Eksperimen dengan rancangan pretest postest non-equivalent control group design. Penentuan sampel mempertimbangkan kemampuan kognitif yang setara antara dua kelas yang menjadi kelompok kontrol dan kelompok eksperimen. Keterampilan proses sains diukur melalui tes tulis yang kemudian dianalisis dengan rubrik penilaian yang sudah disesuaikan untuk setiap aspek keterampilan proses sains. Hasil penelitian menunjukkan bahwa ada pengaruh pembelajaran Project Based Learning terhadap keterampilan proses sains siswa.

  18. Higher order thinking skills: using e-portfolio in project-based learning

    Science.gov (United States)

    Lukitasari, M.; Handhika, J.; Murtafiah, W.

    2018-03-01

    The purpose of this research is to describe students' higher-order thinking skills through project-based learning using e-portfolio. The method used in this research is descriptive qualitative method. The research instruments used were test, unstructured interview, and documentation. Research subjects were students of mathematics, physics and biology education department who take the Basics Physics course. The result shows that through project-based learning using e-portfolio the students’ ability to: analyze (medium category, N-Gain 0.67), evaluate (medium category, N-Gain 0.51), and create (medium Category, N-Gain 0.44) are improved.

  19. ORGANIZATION OF FUTURE ENGINEERS' PROJECT-BASED LEARNING WHEN STUDYING THE PROJECT MANAGEMENT METHODOLOGY

    Directory of Open Access Journals (Sweden)

    Halyna V. Lutsenko

    2015-02-01

    Full Text Available The peculiarities of modern world experience of implementation of project-based learning in engineering education have been considered. The potential role and place of projects in learning activity have been analyzed. The methodology of organization of project-based activity of engineering students when studying the project management methodology and computer systems of project management has been proposed. The requirements to documentation and actual results of students' projects have been described in detail. The requirements to computer-aided systems of project management developed by using Microsoft Project in the scope of diary scheduling and resources planning have been formulated.

  20. Physics meets fine arts: a project-based learning path on infrared imaging

    Science.gov (United States)

    Bonanno, A.; Bozzo, G.; Sapia, P.

    2018-03-01

    Infrared imaging represents a noninvasive tool for cultural heritage diagnostics, based on the capability of IR radiation to penetrate the most external layers of different objects (as for example paintings), revealing hidden features of artworks. From an educational viewpoint, this diagnostic technique offers teachers the opportunity to address manifold topics pertaining to the physics and technology of electromagnetic radiation, with particular emphasis on the nature of color and its physical correlates. Moreover, the topic provides interesting interdisciplinary bridges towards the human sciences. In this framework, we present a hands-on learning sequence, suitable for both high school students and university freshmen, inspired by the project-based learning (PBL) paradigm, designed and implemented in the context of an Italian national project aimed at offering students the opportunity to participate in educational activities within a real working context. In a preliminary test we involved a group of 23 high school students while they were working as apprentices in the Laboratory of Applied Physics for Cultural Heritage (ArcheoLab) at the University of Calabria. Consistently with the PBL paradigm, students were given well-defined practical goals to be achieved. As final goals they were asked (i) to construct and to test a low cost device (based on a disused commercial camera) appropriate for performing educational-grade IR investigations on paintings, and (ii) to prepare a device working as a simple spectrometer (recycling the optical components of a disused video projector), suitable for characterizing various light sources in order to identify the most appropriate for infrared imaging. The proposed learning path has shown (in the preliminary test) to be effective in fostering students’ interest towards physics and its technological applications, especially because pupils perceived the context (i.e. physics applied to the protection and restoration of cultural

  1. Exploring the experiences of female students in introductory project-based engineering courses at two- and four-year institutions

    Science.gov (United States)

    Swan, Amy K.

    2011-12-01

    This qualitative study explored the experiential and contextual factors that shaped female students' pathways into introductory project-based engineering classes at two community colleges and one four-year institution, as well as female students' experiences within and outside of these classes. The study was framed by Social Cognitive Career Theory (SCCT) (Lent, Brown & Hackett, 1996) and Bronfenbrenner's (1979) ecological systems theory. Findings were based on analyses of data gathered through multiple methods: observations; individual interviews with female students; focus group interviews with project teams; and document collection. The findings of this study revealed that while positive experiences with math or science were a likely pre-cursor to engineering interest, experiential learning appeared to be a more powerful force in fostering students' engineering interest. Specifically, participants developed an interest in engineering through academic, professional, and extracurricular engineering- and design-related activities that familiarized them with the tasks and skills involved in engineering work and helped them develop a sense of selfefficacy with regard to this work. Interest and self-efficacy, in turn, played a role in students' postsecondary educational decision-making processes, as did contextual factors including families and finances. This study's findings also showed that participants' project teams were a critically important microsystem within participants' ecological environments. Within this sometimes "chilly" microsystem, female students negotiated intrateam processes, which were in some cases affected by gender norms. Intrateam processes that influenced female students' project-based learning experiences included: interpersonal dynamics; leadership; and division of labor. This study also identified several ways in which the lived experiences of participants at the community colleges were different from, or similar to, those of participants

  2. Optical and electrical characterizations of a single step ion beam milling mesa devices of chloride passivated PbS colloidal quantum dots based film

    Energy Technology Data Exchange (ETDEWEB)

    Hechster, Elad, E-mail: elad.hechster@gmail.com; Sarusi, Gabby [Electro-Optics Engineering Unit and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva, 84100 Israel (Israel); Shapiro, Arthur; Lifshitz, Efrat [Schulich Faculty of Chemistry, Solid State Institute, Russel Berrie Nanotechnology Institute, Technion – Israel Institute of technology, 32000 Haifa (Israel)

    2016-07-15

    Colloidal Quantum Dots (CQDs) are of increasing interest, thanks to their quantum size effect that gives rise to their usage in various applications, such as biological tagging, solar cells and as the sensitizing layer of night vision devices. Here, we analyze the optical absorbance of chloride passivated PbS CQDs as well as revealing a correlation between their photoluminescence and sizes distribution, using theoretical models and experimental results from the literature. Next, we calculate the CQDs resistivity as a film. Although resistivity can be calculated from sheet resistance measurement using four point probes, such measurement is usually carried-out on the layer’s surface that in most cases has dangling bonds and surface states, which might affect the charges flow and modify the resistivity. Therefore; our approach, which was applied in this work, is to extract the actual resistivity from measurements that are performed along the film’s thickness (z-direction). For this intent, we fabricated gold capped PbS mesas devices using a single step Ion Beam Milling (IBM) process where we milled the gold and the PbS film continually, and then measured the vertical resistance. Knowing the mesas’ dimensions, we calculate the resistivity. To the best of our knowledge, no previous work has extracted, vertically, the resistivity of chloride passivated PbS CQDs using the above method.

  3. Quasiparticle self-consistent GW calculations for PbS, PbSe, and PbTe: Band structure and pressure coefficients

    DEFF Research Database (Denmark)

    Svane, Axel; Christensen, Niels Egede; Cardona,, M.

    2010-01-01

    The electronic band structures of PbS, PbSe, and PbTe in the rocksalt structure are calculated with the quasiparticle self-consistent GW (QSGW) approach with spin-orbit coupling included. The semiconducting gaps and their deformation potentials as well as the effective masses are obtained. The GW...

  4. Optical and electrical characterizations of a single step ion beam milling mesa devices of chloride passivated PbS colloidal quantum dots based film

    International Nuclear Information System (INIS)

    Hechster, Elad; Sarusi, Gabby; Shapiro, Arthur; Lifshitz, Efrat

    2016-01-01

    Colloidal Quantum Dots (CQDs) are of increasing interest, thanks to their quantum size effect that gives rise to their usage in various applications, such as biological tagging, solar cells and as the sensitizing layer of night vision devices. Here, we analyze the optical absorbance of chloride passivated PbS CQDs as well as revealing a correlation between their photoluminescence and sizes distribution, using theoretical models and experimental results from the literature. Next, we calculate the CQDs resistivity as a film. Although resistivity can be calculated from sheet resistance measurement using four point probes, such measurement is usually carried-out on the layer’s surface that in most cases has dangling bonds and surface states, which might affect the charges flow and modify the resistivity. Therefore; our approach, which was applied in this work, is to extract the actual resistivity from measurements that are performed along the film’s thickness (z-direction). For this intent, we fabricated gold capped PbS mesas devices using a single step Ion Beam Milling (IBM) process where we milled the gold and the PbS film continually, and then measured the vertical resistance. Knowing the mesas’ dimensions, we calculate the resistivity. To the best of our knowledge, no previous work has extracted, vertically, the resistivity of chloride passivated PbS CQDs using the above method.

  5. Business and Industry Project-Based Capstone Courses: Selecting Projects and Assessing Learning Outcomes

    Science.gov (United States)

    Maleki, Reza A.

    2009-01-01

    This is the first of two articles in which the author shares experiences gained from the development and delivery of a business/industry project-based capstone course. The course integrates research, proposal development and design experience based on knowledge and skills acquired in earlier coursework. The course also incorporates standards and…

  6. Business and Industry Project-Based Capstone Courses: A Reflection on the Performance of Student Teams

    Science.gov (United States)

    Maleki, Reza A.

    2009-01-01

    This is the second of two articles in which the author shares experiences gained from the development and delivery of a business/industry project-based capstone course. The course integrates research, proposal development and design experience based on knowledge and skills acquired in earlier coursework. It also incorporates standards and…

  7. The Robotic Decathlon: Project-Based Learning Labs and Curriculum Design for an Introductory Robotics Course

    Science.gov (United States)

    Cappelleri, D. J.; Vitoroulis, N.

    2013-01-01

    This paper presents a series of novel project-based learning labs for an introductory robotics course that are developed into a semester-long Robotic Decathlon. The last three events of the Robotic Decathlon are used as three final one-week-long project tasks; these replace a previous course project that was a semester-long robotics competition.…

  8. The Integration of Project-Based Methodology into Teaching in Machine Translation

    Science.gov (United States)

    Madkour, Magda

    2016-01-01

    This quantitative-qualitative analytical research aimed at investigating the effect of integrating project-based teaching methodology into teaching machine translation on students' performance. Data was collected from the graduate students in the College of Languages and Translation, at Imam Muhammad Ibn Saud Islamic University, Riyadh, Saudi…

  9. Meta-Assessment in a Project-Based Systems Engineering Course

    Science.gov (United States)

    Wengrowicz, Niva; Dori, Yehudit Judy; Dori, Dov

    2017-01-01

    Project-based learning (PBL) facilitates significant learning, but it poses a major assessment challenge for assessing individual content knowledge. We developed and implemented an assessment approach and tool for a mandatory undergraduate systems engineering PBL-based course. We call this type of assessment "student-oriented"…

  10. Project-Based Social Justice Mathematics: A Case Study of Five 6th Grade Students

    Science.gov (United States)

    McHugh, Maighread L.

    2015-01-01

    The purpose of this qualitative multiple case study was to explore how five sixth grade female students navigated the process of project-based learning as they designed and implemented their own project centered on mathematics while using a social justice lens. The theoretical frameworks of Authentic Intellectual Work and Social Justice…

  11. Collaboration, Intragroup Conflict, and Social Skills in Project-Based Learning

    Science.gov (United States)

    Lee, Dabae; Huh, Yeol; Reigeluth, Charles M.

    2015-01-01

    This case study was conducted in two high school classrooms that utilized collaborative project-based learning (PBL). Collaboration is an important instructional strategy, especially used in conjunction with PBL, and is an essential learning outcome for the twenty-first century. This study examined how collaboration can be achieved as a learning…

  12. Integrating Community into the Classroom: Community Gardening, Community Involvement, and Project-Based Learning.

    Science.gov (United States)

    Langhout, Regina Day; Rappaport, Julian; Simmons, Doretha

    2002-01-01

    Culturally relevant, ongoing project-based learning was facilitated in a predominantly African American urban elementary school via a community garden project. The project involved teachers, students, university members, and community members. This article evaluates the project through two classroom-community collaboration models, noting common…

  13. Using MBTI for the Success Assessment of Engineering Teams in Project-Based Learning

    Science.gov (United States)

    Rodríguez Montequín, V.; Mesa Fernández, J. M.; Balsera, J. Villanueva; García Nieto, A.

    2013-01-01

    Project-Based Learning (PBL) is a teaching and learning methodology that emphasizes student centered instruction by assigning projects. The students have to conduct significant projects and cope with realistic working conditions and scenarios. PBL is generally done by groups of students working together towards a common goal. Several factors play…

  14. Leadership in project-based organizations: Dealing with complex and paradoxical demands

    NARCIS (Netherlands)

    Havermans, L.A.

    2014-01-01

    Despite the overwhelming amount of attention given by scientists and practitioners to leadership, most theories of leadership have been developed to explain the role of leadership in traditional line organizations, not to explain how leaders deal with complex and paradoxical demands in project-based

  15. Fundraising Strategies Developed by MBA Students in Project-Based Learning Courses

    Science.gov (United States)

    Arantes do Amaral, Joao Alberto; Petroni, Liége Mariel; Hess, Aurélio

    2016-01-01

    The ability to raise funds is a skill that most modern project managers need. While a good deal of literature exists on the strategies NGOs employ to raise funds for their operations, less attention has been paid to the strategies used by students involved in Project-Based Learning courses that often partner with NGOs. Fundraising is an important…

  16. Two Project-Based Strategies in an Interdisciplinary Mathematical Modeling in Biology Course

    Science.gov (United States)

    Ludwig, Patrice; Tongen, Anthony; Walton, Brian

    2018-01-01

    James Madison University faculty team-teach an interdisciplinary mathematical modeling course for mathematics and biology students. We have used two different project-based approaches to emphasize the mathematical concepts taught in class, while also exposing students to new areas of mathematics not formally covered in class. The first method…

  17. Rocket to Creativity: A Field Experience in Problem-Based and Project-Based Learning

    Science.gov (United States)

    Dole, Sharon F.; Bloom, Lisa A.; Doss, Kristy Kowalske

    2016-01-01

    This article reports the impact of a field experience in problem-based (PBL) and project-based learning (PjBL) on in-service teachers' conceptions of experiential learning. Participants had been enrolled in a hybrid class that included an online component in which they learned about PBL and PjBL, and an experiential component in which they…

  18. PENGARUH MODEL PROJECT BASED LEARNING TERHADAP KEMAMPUAN BERPIKIR KREATIF MATEMATIKA SISWA

    Directory of Open Access Journals (Sweden)

    Hesti Noviyana

    2017-09-01

    Full Text Available Abstract: The problems in this study relate to the learning model of Project Based Learning and students' creative thinking ability in mathematics. The purpose of the research to know the influence of the model of Project Based Learning on the ability to think creatively mathematics students VIII grade even semester SMP Negeri 3 Bandar Lampung lesson 2016/2017 . The research used experimental method with the population that is all students of class VIII with the amount of 347, while the sample is taken 2 class that is class VIII A as experiment class which amounted to 31, class VIII C as control class which amounted 30. The sample was taken using Cluster Random Sampling technique. To know the ability of creative thinking mathematics students authors perform tests in the form of essays as many as 5 questions that have been tested the validity and reliability. Hypothesis testing in this study using t test. From the results of hypothesis testing using t-test obtained t value = 14.27. From the distribution table t at the significant level of 5% is known t = 2.00 means t> t, so it can be concluded "There is Influence of Model Based Project Based on the Ability of Creative Thinking Mathematics Students".Keywords: Project Based Learning, creative thinking ability of mathematics

  19. How to Make Reminiscence Movies: A Project-Based Gerontology Course

    Science.gov (United States)

    Yancura, Loriena A.

    2013-01-01

    One key to successful gerontological education lies in teaching students to integrate information from diverse academic disciplines into practical contexts. This article describes a project-based course within which students learn to integrate theories by working with older adult partners to make reminiscence movies based on an important event or…

  20. "Does Hope Change? Testing a Project-Based Health Intervention among Urban Students of Color"

    Science.gov (United States)

    Zusevics, Kaija L.; Johnson, Sheri

    2014-01-01

    Hope is positively correlated with educational attainment and health. Interventions based on project-based learning (PBL) may increase youth hope. This study examined how a PBL intervention affected hope among urban students of color. Students in health classes were invited to participate. A PBL health class was implemented in four classrooms. The…

  1. Application of Project-Based Learning (PBL) to the Teaching of Electrical Power Systems Engineering

    Science.gov (United States)

    Hosseinzadeh, N.; Hesamzadeh, M. R.

    2012-01-01

    Project-based learning (PBL), a learning environment in which projects drive learning, has been successfully used in various courses in the educational programs of different disciplines. However, concerns have been raised as to the breadth of the content covered and, in particular, whether PBL can be applied to specialized subjects without…

  2. Project-Based Method as an Effective Means of Interdisciplinary Interaction While Teaching a Foreign Language

    Science.gov (United States)

    Bondar, Irina Alekseevna; Kulbakova, Renata Ivanovna; Svintorzhitskaja, Irina Andreevna; Pilat, Larisa Pavlovna; Zavrumov, Zaur Aslanovich

    2016-01-01

    The article explains how to use a project-based method as an effective means of interdisciplinary interaction when teaching a foreign language on the example of The Institute of service, tourism and design (branch) of the North Caucasus Federal University (Pyatigorsk, Stavropol Territory Russia). The article holds the main objectives of the…

  3. Meaningful Learning in the Teaching of Culture: The Project Based Learning Approach

    Science.gov (United States)

    Kean, Ang Chooi; Kwe, Ngu Moi

    2014-01-01

    This paper reports on a collaborative effort taken by a team of three teacher educators in using the Project Based Learning (PBL) approach in the teaching of Japanese culture with the aim to investigate the presence of actual "meaningful learning" among 15 students of a 12-Week Preparatory Japanese Language course under a teacher…

  4. Project Based Learning (PjBL) Practices at Politeknik Kota Bharu, Malaysia

    Science.gov (United States)

    Rahman, Md. Baharuddin Haji Abdul; Daud, Khairul Azhar Mat; Jusoff, Kamaruzaman; Ghani, Nik Azida Abd

    2009-01-01

    This study explores the utilization of Project-based Learning module in the subject of project development for the Mechanical Engineering students at Politeknik Kota Bharu. This study focuses on the development of the PjBL module based on socio-constructivist approach. The objective of this study is to explore the influence of the utilization of…

  5. A New Project-Based Curriculum of Design Thinking with Systems Engineering Techniques

    NARCIS (Netherlands)

    Haruyama, S.; Kim, S.K.; Beiter, K.A.; Dijkema, G.P.J.; De Weck, O.L.

    2012-01-01

    We developed a new education curriculum called "ALPS" (Active Learning Project Sequence) at Keio University that emphasizes team project-based learning and design thinking with systems engineering techniques. ALPS is a 6 month course, in which students work as a team and design and propose

  6. Case Study of a Project-Based Learning Course in Civil Engineering Design

    Science.gov (United States)

    Gavin, K.

    2011-01-01

    This paper describes the use of project-based learning to teach design skills to civil engineering students at University College Dublin (UCD). The paper first considers the development of problem-based leaning (PBL) as a tool in higher education. The general issues to be considered in the design of the curriculum for a PBL module are reviewed.…

  7. A Project-Based Cornerstone Course in Civil Engineering: Student Perceptions and Identity Development

    Science.gov (United States)

    Marshall, Jill; Bhasin, Amit; Boyles, Stephen; David, Bernard; James, Rachel; Patrick, Anita

    2018-01-01

    Our study used a natural experiment to compare a project-based cornerstone course with the traditionally-taught introductory course in civil engineering. During the study, two sections of the course were organized around an overarching project, the design of an event center, and the remaining sections used guest lectures, a textbook, and…

  8. Managing for the triple bottom line in project-based learning

    CSIR Research Space (South Africa)

    Viljoen, NM

    2012-07-01

    Full Text Available Project-based learning is a popular engineering education approach that involves at least three stakeholders – students, faculty and an external client. But more often than not, one or more of these parties have to compromise their goals...

  9. Proactive behaviour may lead to failure in virtual project-based collaborative learning

    DEFF Research Database (Denmark)

    Bjørn, Pernille; Hertzum, Morten

    2005-01-01

    This paper argues that proactive behaviour, caused by high engagement and motivation of the learners, may lead to failure of collaborative learning. By examining empirical data from real-world text-only virtual negotiations between dispersed participants engaged in project-based collaborative...

  10. Operations Strategy Development in Project-based Production – a building contractor implements Lean

    DEFF Research Database (Denmark)

    Koch, Christian; Friis, Ole Uhrskov

    2015-01-01

    Purpose: To study how operations strategy innovation occurs in project-based production and organisation. Design/methodology/approach: A longitudinal case study encompassing the processes at the company headquarters and in two projects using Lean. Findings: The operations strategy development com...

  11. A Project-Based Laboratory for Learning Embedded System Design with Industry Support

    Science.gov (United States)

    Lee, Chyi-Shyong; Su, Juing-Huei; Lin, Kuo-En; Chang, Jia-Hao; Lin, Gu-Hong

    2010-01-01

    A project-based laboratory for learning embedded system design with support from industry is presented in this paper. The aim of this laboratory is to motivate students to learn the building blocks of embedded systems and practical control algorithms by constructing a line-following robot using the quadratic interpolation technique to predict the…

  12. Scaffolding Project-Based Learning with the Project Management Body of Knowledge (PMBOK[R])

    Science.gov (United States)

    van Rooij, Shahron Williams

    2009-01-01

    This paper reports the results of a study of the extent to which processes and procedures from the discipline of project management can scaffold online project-based learning in a graduate-level instructional technology course, by facilitating intra-team interaction, enhancing project outcomes and promoting a positive project team experience. With…

  13. Project-Based Learning: A Promising Approach to Improving Student Outcomes. Issue Focus

    Science.gov (United States)

    Quint, Janet; Condliffe, Barbara

    2018-01-01

    The concept of project-based learning (PBL) has garnered wide support among a number of K-12 education policy advocates and funders. PBL is viewed as an approach that enables students to develop the "21st century competencies"--cognitive and socioemotional skills--needed for success in college and careers. This issue focus, pulling from…

  14. Expanding Omani Learners' Horizons through Project-Based Learning: A Case Study

    Science.gov (United States)

    Dauletova, Victoria

    2014-01-01

    As a relatively innovative teaching/learning approach in the Arabian Gulf region, in general, and in Oman, in particular, project-based learning requires progressive amendments and adaptations to the national culture of the learner. This article offers analysis of the current state of the approach in the local educational environment. Furthermore,…

  15. The Effect of Project Based Learning on Seventh Grade Students' Academic Achievement

    Science.gov (United States)

    Kizkapan, Oktay; Bektas, Oktay

    2017-01-01

    The purpose of this study is to investigate whether there is a significant effect of project based learning approach on seventh grade students' academic achievement in the structure and properties of matter. In the study, according to the characteristics of quantitative research methods, pretest-posttest control group quasi-experimental design was…

  16. Bringing Curriculum to Life. Enacting Project-Based Learning in Music Programs

    Science.gov (United States)

    Tobias, Evan S.; Campbell, Mark Robin; Greco, Phillip

    2015-01-01

    At its core, project-based learning is based on the idea that real-life problems capture student interest, provoke critical thinking, and develop skills as they engage in and complete complex undertakings that typically result in a realistic product, event, or presentation to an audience. This article offers a starting point for music teachers who…

  17. Implementation of a Project-Based Engineering School: Increasing Student Motivation and Relevant Learning

    Science.gov (United States)

    Terrón-López, María-José; García-García, María-José; Velasco-Quintana, Paloma-Julia; Ocampo, Jared; Vigil Montaño, María-Reyes; Gaya-López, María-Cruz

    2017-01-01

    The School of Engineering at Universidad Europea de Madrid (UEM) implemented, starting in the 2012-2013 period, a unified academic model based on project-based learning as the methodology used throughout the entire School. This model expects that every year, in each grade, all the students should participate in a capstone project integrating the…

  18. Project-Based Learning through the Eyes of Teachers and Students in Adult ESL Classrooms

    Science.gov (United States)

    Petersen, Cristina; Nassaji, Hossein

    2016-01-01

    The use of projects and project-based learning has recently received much attention as a way of promoting meaning-focused communication and integrating different language skills into second and foreign language classrooms. However, perspectives on the effective implementation of projects have not been fully explored. This study examines and…

  19. Increasing EFL Learners' Oral Production at a Public School through Project-Based Learning

    Science.gov (United States)

    Vaca Torres, Ady Marcela; Gómez Rodríguez, Luis Fernando

    2017-01-01

    This research study examined how a group of ninth graders enhanced the speaking skill in an English as a foreign language classroom through project-based learning. Data about the experience were collected through field notes, transcripts of learners' oral performance, and one interview. Grounded theory was implemented for data analysis, out of…

  20. Project based learning in organizations: towards a methodology for learning in groups

    NARCIS (Netherlands)

    Poell, R.F.; Krogt, F.J. van der

    2003-01-01

    This article introduces a methodology for employees in organizations to set up and carry out their own group learning projects. It is argued that employees can use project-based learning to make their everyday learning more systematic at times, without necessarily formalizing it. The article

  1. Becoming Little Scientists: Technologically-Enhanced Project-Based Language Learning

    Science.gov (United States)

    Dooly, Melinda; Sadler, Randall

    2016-01-01

    This article outlines research into innovative language teaching practices that make optimal use of technology and Computer-Mediated Communication (CMC) for an integrated approach to Project-Based Learning. It is based on data compiled during a 10- week language project that employed videoconferencing and "machinima" (short video clips…

  2. Jumping In: Redefining Teaching and Learning in Physical Education through Project-Based Learning

    Science.gov (United States)

    Coyne, Jaime; Hollas, Tori; Potter, Jalene P.

    2016-01-01

    Project-based learning (PBL) is an inquiry-based instructional approach that allows students to gain knowledge and skills by investigating and respond to engaging, complex problems or challenges. For some, PBL may seem like an unnatural fit in PE classrooms. However, this article describes how, with careful and creative planning, PBL can easily…

  3. Choose to Use: Scaffolding for Technology Learning Needs in a Project-Based Learning Environment

    Science.gov (United States)

    Weimer, Peggy D.

    2017-01-01

    Project-based learning is one approach used by teachers to meet the challenge of developing more technologically proficient students. This approach, however, requires students to manage a large number of tasks including the mastery of technology. If a student's perception that their capability to perform a task falls below the task's difficulty,…

  4. The Effect on the 8th Grade Students' Attitude towards Statistics of Project Based Learning

    Science.gov (United States)

    Koparan, Timur; Güven, Bülent

    2014-01-01

    This study investigates the effect of the project based learning approach on 8th grade students' attitude towards statistics. With this aim, an attitude scale towards statistics was developed. Quasi-experimental research model was used in this study. Following this model in the control group the traditional method was applied to teach statistics…

  5. Sparking Passion: Engaging Student Voice through Project-Based Learning in Learning Communities

    Science.gov (United States)

    Ball, Christy L.

    2016-01-01

    How do we confront entrenched educational practices in higher education that lead to student demotivation, poor retention, and low persistence? This article argues that project-based learning that situates student voice and capacity at the center of culturally-responsive curriculum has the potential to spark student passion for problem-solving…

  6. Project-based learning in organizations : Towards a methodology for learning in groups

    NARCIS (Netherlands)

    Poell, R.F.; van der Krogt, F.J.

    2003-01-01

    This article introduces a methodology for employees in organizations to set up and carry out their own group learning projects. It is argued that employees can use project-based learning to make their everyday learning more systematic at times, without necessarily formalizing it. The article

  7. Project-Based Learning in Colleges of Business: Is It Enough to Develop Educated Graduates?

    Science.gov (United States)

    Smith, Penny Pence; Gibson, Lindsey A.

    2016-01-01

    This chapter focuses on project-based learning in colleges of business, a concept that offers the student a "hands-on" approach to knowledge by working on actual projects with business community organizations. However, it may take more than such partnerships to assure graduates become "educated people" as well as those…

  8. Increase Student Engagement through Project-Based Learning. Best Practices Newsletter

    Science.gov (United States)

    Southern Regional Education Board (SREB), 2015

    2015-01-01

    We learn by doing. This simple philosophy is at the heart of project-based learning in the 21st-century classroom. It is grounded in the belief that the stand and lecture approach to teaching, worksheets and rote memorization are not enough to move students down a path to the deep learning necessary for success in college and careers. Essential…

  9. Voices from the Field: Developing Employability Skills for Archaeological Students Using a Project Based Learning Approach

    Science.gov (United States)

    Wood, Gaynor

    2016-01-01

    Graduate employment statistics are receiving considerable attention in UK universities. This paper looks at how a wide range of employability attributes can be developed with students, through the innovative use of the Project Based Learning (PjBL) approach. The case study discussed here involves a group of archaeology students from the University…

  10. Effects of Implementing STEM-I Project-Based Learning Activities for Female High School Students

    Science.gov (United States)

    Lou, Shi-Jer; Tsai, Huei-Yin; Tseng, Kuo-Hung; Shih, Ru-Chu

    2014-01-01

    This study aims to explore the application of STEM-I (STEM-Imagination) project-based learning activities and its effects on the effectiveness, processes, and characteristics of STEM integrative knowledge learning and imagination development for female high school students. A total of 72 female high school students were divided into 18 teams.…

  11. Interdisciplinary Project-Based Learning: An Online Wiki Experience in Teacher Education

    Science.gov (United States)

    Biasutti, Michele; EL-Deghaidy, Heba

    2015-01-01

    In the current research study the use of Wikis as an online didactic tool to apply project-based learning in higher education was reported. The study was conducted in university teacher education programmes. During the online activities, participants developed interdisciplinary projects for the primary school working collaboratively in small…

  12. Promoting Information Literacy of Pre-Medical Students through Project-Based Learning: A Pilot Study

    Science.gov (United States)

    Saliba, Reya; Mussleman, Paul; Fernandes, Melanie; Bendriss, Rachid

    2017-01-01

    This study describes the implementation of information literacy (IL) skills through the use of the project-based learning (PjBL) method in an English for Academic Purposes (EAP) course. Participants were Arabic speaking students enrolled in the Foundation Program that prepared them for the pre-medical curriculum in a U.S. medical college in the…

  13. Exploring the Effects of Project-Based Learning in Secondary Mathematics Education

    Science.gov (United States)

    Holmes, Vicki-Lynn; Hwang, Yooyeun

    2016-01-01

    This mixed-method, longitudinal study investigated the benefits of project-based learning (PBL) on secondary-mathematics students' academic skill development and motivated strategies for learning (i.e., cognitive, social, and motivational). The focus of this study was academic skill development (algebra- and geometry-assessment scores) and other…

  14. Cultivating Preservice Secondary Teachers for Project-Based Learning: A Four-Step Model

    Science.gov (United States)

    Zhang, Gaoming; Ridgway, Angelia J.; Sachs, Deb

    2015-01-01

    This article describes four different mechanisms for preparing teacher candidates from a liberal arts institution to teach in project based learning (PBL) classrooms: Observe it, Experience it, Create it, and Become it. For each of the four mechanisms, the authors also provide concrete examples of candidates' PBL experiences and candidates'…

  15. Health-Related Fitness Knowledge Development through Project-Based Learning

    Science.gov (United States)

    Hastle, Peter A.; Chen, Senlin; Guarino, Anthony J.

    2017-01-01

    Purpose: The purpose of this study was to examine the process and outcome of an intervention using the project-based learning (PBL) model to increase students' health-related fitness (HRF) knowledge. Method: The participants were 185 fifth-grade students from three schools in Alabama (PBL group: n = 109; control group: n = 76). HRF knowledge was…

  16. Motivation Management of Project-Based Learning for Business English Adult Learners

    Science.gov (United States)

    Liu, Xiaoqin

    2016-01-01

    The paper finds out poor engagement in business English training program prevents adult learners at College of Continuing Education of Guangdong University of Foreign Studies from improving their communication skills. PBL (Project-Based Learning) is proposed to motivate adult learners to get involved with learning a lot. Based on the perspective…

  17. Using Project-Based Learning and Google Docs to Support Diversity

    Science.gov (United States)

    Leh, Amy

    2014-01-01

    A graduate course, ETEC543 ("Technology and Learning I"), was revised to better serve increasing new student population, international students, in an academic program. Project-based learning, Google Docs, and instructional strategies fostering diversity and critical thinking were incorporated into the course redesign. Observations,…

  18. The Dynamics of Project-Based Learning Extension Courses: The "Laboratory of Social Projects" Case Study

    Science.gov (United States)

    Arantes do Amaral, Joao Alberto

    2017-01-01

    In this case study we discuss the dynamics that drive a free-of-charge project-based learning extension course. We discuss the lessons learned in the course, "Laboratory of Social Projects." The course aimed to teach project management skills to the participants. It was conducted from August to November of 2015, at Federal University of…

  19. Project-Based Learning and Design-Focused Projects to Motivate Secondary Mathematics Students

    Science.gov (United States)

    Remijan, Kelly W.

    2017-01-01

    This article illustrates how mathematics teachers can develop design-focused projects, related to project-based learning, to motivate secondary mathematics students. With first-hand experience as a secondary mathematics teacher, I provide a series of steps related to the engineering design process, which are helpful to teachers in developing…

  20. The Relationship between Project-Based Learning and Rigor in STEM-Focused High Schools

    Science.gov (United States)

    Edmunds, Julie; Arshavsky, Nina; Glennie, Elizabeth; Charles, Karen; Rice, Olivia

    2016-01-01

    Project-based learning (PjBL) is an approach often favored in STEM classrooms, yet some studies have shown that teachers struggle to implement it with academic rigor. This paper explores the relationship between PjBL and rigor in the classrooms of ten STEM-oriented high schools. Utilizing three different data sources reflecting three different…

  1. Evolution of Project-Based Learning in Small Groups in Environmental Engineering Courses

    Science.gov (United States)

    Requies, Jesús M.; Agirre, Ion; Barrio, V. Laura; Graells, Moisès

    2018-01-01

    This work presents the assessment of the development and evolution of an active methodology (Project-Based Learning--PBL) implemented on the course "Unit Operations in Environmental Engineering", within the bachelor's degree in Environmental Engineering, with the purpose of decreasing the dropout rate in this course. After the initial…

  2. An Adaptive Approach to Managing Knowledge Development in a Project-Based Learning Environment

    Science.gov (United States)

    Tilchin, Oleg; Kittany, Mohamed

    2016-01-01

    In this paper we propose an adaptive approach to managing the development of students' knowledge in the comprehensive project-based learning (PBL) environment. Subject study is realized by two-stage PBL. It shapes adaptive knowledge management (KM) process and promotes the correct balance between personalized and collaborative learning. The…

  3. Updating Assessment Styles: Website Development Rather than Report Writing for Project Based Learning Courses

    Science.gov (United States)

    Brown, Nicola

    2017-01-01

    While teaching methods tend to be updated frequently, the implementation of new innovative assessment tools is much slower. For example project based learning has become popular as a teaching technique, however, the assessment tends to be via traditional reports. This paper reports on the implementation and evaluation of using website development…

  4. The Effect of Project-Based Learning on Students' Statistical Literacy Levels for Data Representation

    Science.gov (United States)

    Koparan, Timur; Güven, Bülent

    2015-01-01

    The point of this study is to define the effect of project-based learning approach on 8th Grade secondary-school students' statistical literacy levels for data representation. To achieve this goal, a test which consists of 12 open-ended questions in accordance with the views of experts was developed. Seventy 8th grade secondary-school students, 35…

  5. Challenge Study: A Project-Based Learning on a Wireless Communication System at Technical High School

    Science.gov (United States)

    Terasawa, Ikuo

    2016-01-01

    The challenge study is a project based learning curriculum at Technical High School aimed at the construction of a wireless communication system. The first period was engineering issues in the construction of an artificial satellite and the second period was a positional locating system based on the general purpose wire-less device--ZigBee device.…

  6. The Effect of Project Based Learning on the Statistical Literacy Levels of Student 8th Grade

    Science.gov (United States)

    Koparan, Timur; Güven, Bülent

    2014-01-01

    This study examines the effect of project based learning on 8th grade students' statistical literacy levels. A performance test was developed for this aim. Quasi-experimental research model was used in this article. In this context, the statistics were taught with traditional method in the control group and it was taught using project based…

  7. Overcoming Barriers between Volunteer Professionals Advising Project-Based Learning Teams with Regulation Tools

    Science.gov (United States)

    Rees Lewis, Daniel G.; Easterday, Matthew W.; Harburg, Emily; Gerber, Elizabeth M.; Riesbeck, Christopher K.

    2018-01-01

    To provide the substantial support required for project-based learning (PBL), educators can incorporate professional experts as "design coaches." However, previous work shows barriers incorporating design coaches who can rarely meet face-to-face: (1) communication online is time-consuming, (2) updating coaches online is not perceived as…

  8. The Impact of Project-Based Learning on Minority Student Achievement: Implications for School Redesign

    Science.gov (United States)

    Cervantes, Bernadine; Hemmer, Lynn; Kouzekanani, Kamiar

    2015-01-01

    Project-Based Learning (PBL) serves as an instructional approach to classroom teaching and learning that is designed to engage students in the investigation of real-world problems to create meaningful and relevant educational experiences. The causal-comparative study compared 7th and 8th students who had utilized the PBL with a comparison group in…

  9. Pre-Service Teachers' Experiences and Views on Project-Based Learning Processes

    Science.gov (United States)

    Dag, Funda; Durdu, Levent

    2017-01-01

    Project-based learning (PjBL) has been promoted as an effective and frequently used student-centered learning approach for various learning environments. To have various learning experiences with PjBL is an important requirement for pre-service teachers (PSTs). The purpose of the study was to investigate the experiences PSTs had with group work…

  10. Teaching Research Methodology Using a Project-Based Three Course Sequence Critical Reflections on Practice

    Science.gov (United States)

    Braguglia, Kay H.; Jackson, Kanata A.

    2012-01-01

    This article presents a reflective analysis of teaching research methodology through a three course sequence using a project-based approach. The authors reflect critically on their experiences in teaching research methods courses in an undergraduate business management program. The introduction of a range of specific techniques including student…

  11. Promoting Collaboration in a Project-Based E-Learning Context

    Science.gov (United States)

    Papanikolaou, Kyparisia; Boubouka, Maria

    2011-01-01

    In this paper we investigate the value of collaboration scripts for promoting metacognitive knowledge in a project-based e-learning context. In an empirical study, 82 students worked individually and in groups on a project using the e-learning environment MyProject, in which the life cycle of a project is inherent. Students followed a particular…

  12. A project-based system for including farmers in the EU ETS

    DEFF Research Database (Denmark)

    Brandt, Urs Steiner; Svendsen, Gert Tinggaard

    2011-01-01

    as ‘the missing link’ in past climate negotiations. We argue that farmers have relatively low marginal reduction costs and that consequences in terms of the effect on permit price and technology are overall positive in the EU Emission Trading System (ETS). Thus, we propose a project-based system...

  13. A projection-based approach to general-form Tikhonov regularization

    DEFF Research Database (Denmark)

    Kilmer, Misha E.; Hansen, Per Christian; Espanol, Malena I.

    2007-01-01

    We present a projection-based iterative algorithm for computing general-form Tikhonov regularized solutions to the problem minx| Ax-b |2^2+lambda2| Lx |2^2, where the regularization matrix L is not the identity. Our algorithm is designed for the common case where lambda is not known a priori...

  14. Project-Based Community Participatory Action Research Using Geographic Information Technologies

    Science.gov (United States)

    Kim, Minsung

    2018-01-01

    The paper investigates the effects of a project-based community participation course in which students chose research topics relevant to a local community. Specifically, the students undertook the following projects: (1) creating a virtual 3D model of a local government office, (2) creating interactive digitized versions of mountain trails using…

  15. Students' Perceptions of a Project-Based Organic Chemistry Laboratory Environment: A Phenomenographic Approach

    Science.gov (United States)

    Burrows, Nikita L.; Nowak, Montana K.; Mooring, Suazette R.

    2017-01-01

    Students can perceive the laboratory environment in a variety of ways that can affect what they take away from the laboratory course. This qualitative study characterizes undergraduate students' perspectives of a project-based Organic Chemistry laboratory using the theoretical framework of phenomenography. Eighteen participants were interviewed in…

  16. Motivating Students to Develop Satellites in a Problem and Project-Based Learning Environment

    DEFF Research Database (Denmark)

    Larsen, Jesper Abildgaard; Nielsen, Jens Frederik Dalsgaard; Zhou, Chunfang

    2013-01-01

    During the last decade, a total of three student satellites have been developed by engineering students in a Problem and Project-Based Learning (PBL) environment at Aalborg University (AAU), Denmark. As solving such a complex project, we emphasize that a high level of motivation is needed for the...

  17. Integrating Soft Skill Competencies through Project-Based Learning across the Information Systems Curriculum

    Science.gov (United States)

    Woodward, Belle S.; Sendall, Patricia; Ceccucci, Wendy

    2010-01-01

    Contemporary Information Systems graduates will be more marketable in the workplace upon graduation if they have combined competencies in both technical and soft skills: interpersonal communication, teamwork, time management, planning and organizational skills. Team and project-based learning can be used to incorporate soft skill competencies with…

  18. Innovation in project-based companies - A case study in different approaches to organisational change

    DEFF Research Database (Denmark)

    Grex, Sara

    2004-01-01

    This paper asks how project-based organizations can be developed in order to establish and sustain innovation. The question is being explored by examining and comparing two approaches to organizational change. One approach emphasizes planning, regulation and control and creation of changes through...

  19. Mathematical Representation Ability by Using Project Based Learning on the Topic of Statistics

    Science.gov (United States)

    Widakdo, W. A.

    2017-09-01

    Seeing the importance of the role of mathematics in everyday life, mastery of the subject areas of mathematics is a must. Representation ability is one of the fundamental ability that used in mathematics to make connection between abstract idea with logical thinking to understanding mathematics. Researcher see the lack of mathematical representation and try to find alternative solution to dolve it by using project based learning. This research use literature study from some books and articles in journals to see the importance of mathematical representation abiliy in mathemtics learning and how project based learning able to increase this mathematical representation ability on the topic of Statistics. The indicators for mathematical representation ability in this research classifies namely visual representation (picture, diagram, graph, or table); symbolize representation (mathematical statement. Mathematical notation, numerical/algebra symbol) and verbal representation (written text). This article explain about why project based learning able to influence student’s mathematical representation by using some theories in cognitive psychology, also showing the example of project based learning that able to use in teaching statistics, one of mathematics topic that very useful to analyze data.

  20. Linking project-based mechanisms with domestic greenhouse gas emissions trading schemes

    International Nuclear Information System (INIS)

    Bygrave, S.; Bosi, M.

    2004-01-01

    Although there are a number of possible links between emission trading and project-based mechanisms, the focus of this paper is on linking domestic GHG emission trading schemes with: (1) domestic; and, (2) international (JI and CDM) GHG reduction project activities. The objective is to examine some of the challenges in linking DETs and project-based mechanisms, as well as some possible solutions to address these challenges. The link between JI / CDM and intergovernmental international emissions trading (i.e. Article 17 of the Kyoto Protocol) is defined by the Kyoto Protocol, and therefore is not covered in this paper. The paper is written in the context of: (a) countries adhering to the Kyoto Protocol and elaborating their strategies to meet their GHG emission commitments, including through the use of the emissions trading and project-based mechanisms. For example, the European Union (EU) will be commencing a GHG Emissions Trading Scheme in January 2005, and recently, the Council of ministers and the European Parliament agreed on a text for an EU Linking Directive allowing the use of JI and CDM emission units in the EU Emission Trading Scheme (EU-ETS); and (b) all countries (and/or regions within countries) with GHG emission obligations that may choose to use domestic emissions trading and project-based mechanisms to meet their GHG commitments. The paper includes the following elements: (1) an overview of the different flexibility mechanisms (i.e. GHG emissions trading and PBMs), including a brief description and comparisons between the mechanisms (Section 3); (2) an exploration of the issues that emerge when project-based mechanisms link with domestic emissions trading schemes, as well as possible solutions to address some of the challenges raised (Section 4); (3) a case study examining the EU-ETS and the EU Linking Directive on project-based mechanisms, in particular on how the EU is addressing in a practical context relevant linking issues (Section 5); (4) a

  1. Enhanced charge collection and photocatalysis performance of CdS and PbS nanoclusters co-sensitized TiO{sub 2} porous film

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Miao; Xu, Yanyan; Gong, Zezhou; Tao, Jiajia [School of Physics & Material Science, Anhui University, Hefei 230601 (China); Sun, Zhaoqi, E-mail: szq@ahu.edu.cn [School of Physics & Material Science, Anhui University, Hefei 230601 (China); Lv, Jianguo [School of Electronic & Information Engineering, Hefei Normal University, Hefei, 230601 (China); National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Chen, Xiaoshuang [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Jiang, Xishun [School of Physics & Material Science, Anhui University, Hefei 230601 (China); School of Mechanical & Electronic Engineering, Chuzhou University, Chuzhou, 239000 (China); He, Gang; Wang, Peihong; Meng, Fanming [School of Physics & Material Science, Anhui University, Hefei 230601 (China)

    2015-11-15

    A novel translucent TiO{sub 2} porous film was prepared through etched method. The CdS, PbS and CdS/PbS nanoclusters were imbedded on TiO{sub 2} porous film by successive ionic layer adsorption and reaction method. Microstructure, morphology, optical and photoelectron-chemical properties of the as-synthesized thin films were investigated systematically. XRD and morphology analysis showed that PbS or CdS nanoclusters have been attached to the TiO{sub 2} porous films. It was found that the energy band gap of TiO{sub 2} porous film decreased from 3.46 to 3.2 eV after sensitized with nanoclusters. The photocurrent density of ITO/TiO{sub 2} photoelectrode increased from 0.017 to 0.28 mA/cm{sup 2} after co-sensitized with CdS and PbS nanoclusters. Besides, the photoelectrode sensitized with two sorts of nanoclusters showed evident higher photocurrent density than which sensitized just one sort of nanoclusters. The photocurrent density of ITO/TiO{sub 2}/PbS and TO/TiO{sub 2}/CdS photoelectrode was 0.11 mA/cm{sup 2} and 0.22 mA/cm{sup 2} respectively. 0.28 mA/cm{sup 2} can be obtained by ITO/TiO{sub 2}/CdS/PbS photoelectrode. The results showed that the optical and photoelectrochemistry properties and phtotcatalysis performance of TiO{sub 2} porous film were greatly improved by co-sensitized with CdS and PbS nanoclusters. - Graphical abstract: When CdS and PbS were brought in the cascade structure, such a Fermi level alignment causes upward and downward shifts of the band edges for PbS and CdS, respectively. Therefore the resulting band edges for the ITO/TiO{sub 2}/CdS/PbS devices are inferred to have a stepwise structure. The elevated conduction band edge of PbS provides a higher driving force for the injection of photogenerated electrons from PbS to CdS as well as the injection of excited holes from CdS to PbS. Such a structure offers efficient separation and transport of the excited electrons and holes. - Highlights: • Ti films were obtained from direct current

  2. Teaching Cell Biology to Dental Students with a Project-Based Learning Approach.

    Science.gov (United States)

    Costa-Silva, Daniela; Côrtes, Juliana A; Bachinski, Rober F; Spiegel, Carolina N; Alves, Gutemberg G

    2018-03-01

    Although the discipline of cell biology (CB) is part of the curricula of predoctoral dental schools, students often fail to recognize its practical relevance. The aim of this study was to assess the effectiveness of a practical-theoretical project-based course in closing the gaps among CB, scientific research, and dentistry for dental students. A project-based learning course was developed with nine sequential lessons to evaluate 108 undergraduate dental students enrolled in CB classes of a Brazilian school of dentistry during 2013-16. To highlight the relevance of in vitro studies in the preclinical evaluation of dental materials at the cellular level, the students were challenged to complete the process of drafting a protocol and performing a cytocompatibility assay for a bone substitute used in dentistry. Class activities included small group discussions, scientific database search and article presentations, protocol development, lab experimentation, and writing of a final scientific report. A control group of 31 students attended only one laboratory class on the same theme, and the final reports were compared between the two groups. The results showed that the project-based learning students had superior outcomes in acknowledging the relevance of in vitro methods during biocompatibility testing. Moreover, they produced scientifically sound reports with more content on methodological issues, the relationship with dentistry, and the scientific literature than the control group (p<0.05). The project-based learning students also recognized a higher relevance of scientific research and CB to dental practice. These results suggest that a project-based approach can help contextualize scientific research in dental curricula.

  3. Electron-Electron and Electron-Phonon interactions effects on the tunnel electronic spectrum of PbS quantum dots

    Science.gov (United States)

    Wang, Hongyue; Lhuillier, Emmanuel; Yu, Qian; Mottaghizadeh, Alireza; Ulysse, Christian; Zimmers, Alexandre; Dubertret, Benoit; Aubin, Herve

    2015-03-01

    We present a tunnel spectroscopy study of the electronic spectrum of single PbS Quantum Dots (QDs) trapped between nanometer-spaced electrodes, measured at low temperature T=5 K. The carrier filling of the QD can be controlled either by the drain voltage in the shell filling regime or by a gate voltage. In the empty QD, the tunnel spectrum presents the expected signature of the 8x degenerated excited levels. In the drain controlled shell filling regime, the levels degeneracies are lifted by the global electrostatic Coulomb energy of the QD; in the gate controlled shell filling regime, the levels degeneracies are lifted by the intra-Coulomb interactions. In the charged quantum dot, electron-phonons interactions lead to the apparition of Franck-Condon side bands on the single excited levels and possibly Franck Condon blockade at low energy. The sharpening of excited levels at higher gate voltage suggests that the magnitude of electron-phonon interactions is decreased upon increasing the electron filling in the quantum dot. This work was supported by the French ANR Grants 10-BLAN-0409-01, 09-BLAN-0388-01, by the Region Ile-de-France in the framework of DIM Nano-K and by China Scholarship Council.

  4. The fabrication and analysis of a PbS nanocrystal:C{sub 60} bilayer hybrid photovoltaic system

    Energy Technology Data Exchange (ETDEWEB)

    Dissanayake, D M N M [Solid State Electronics Laboratory, University of Michigan, Ann Arbor, MI 48109-2122 (United States); Hatton, R A [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom); Lutz, T [Department of Chemistry, Imperial College, London SW7 2AY (United Kingdom); Curry, R J; Silva, S R P [Advanced Technology Institute, University of Surrey, Guildford GU2 7XH (United Kingdom)], E-mail: ndissa@umich.edu

    2009-06-17

    A near-infrared sensitive hybrid photovoltaic system between PbS nanocrystals (PbS-NCs) and C{sub 60} is demonstrated. Up to 0.44% power conversion efficiency is obtained under AM1.5G with a short circuit current density (J{sub sc}) of 5 mA cm{sup -2} when the PbS-NC layer is treated in anhydrous methanol. The observed J{sub sc} is found be approximately one-third of the maximum expected from this hybrid configuration, indicating the potential for further optimization. Crucial for device operation, a smooth film of nanocrystals is seen to form on the hole transporting poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer deposited on the transparent electrode, facilitated through an ionic interaction between nanocrystal capping ligands and the PEDOT:PSS. The formation of the open circuit voltage in this system is seen to be influenced by an interfacial dipole formed at the hole-extracting electrode, providing insights for further optimization.

  5. Preparation of PbS and PbO nanopowders from new Pb(II)(saccharine) coordination polymers

    International Nuclear Information System (INIS)

    Aslani, Alireza; Musevi, Seyid Javad; Şahin, Ertan; Yilmaz, Veysel T.

    2014-01-01

    Highlights: • The complex of compounds “[Pb(H 2 O)(μ-OAc)(μ-sac)] n ” are synthesized at nano and bulk size structurally diverse and show interesting three-dimensional coordination polymers. • Reduction of the particle size of the coordination polymers to a few dozen nanometers results in lower thermal stability when compared to the single crystalline samples. • This study demonstrates that the metal–organic framework may be suitable precursors for the preparation of nanoscale materials with interesting morphologies. - Abstract: Nanopowders and single crystal of new Pb(II) three-dimensional coordination polymer, [Pb(H 2 O)(μ-OAc)(μ-sac)] n “PASAC” were synthesized by a sonochemical and branched tube methods (Yılmaz et al., Z. Anorg. Allg. Chem. 629 (2003) 172). The new nano-structures of Pb(II) coordination polymer were characterized by X-ray crystallography analysis, scanning electron microscopy (SEM), X-ray powder diffraction (XRD), surface analysis (BET), and IR spectroscopy. The crystal structure of these compounds consists of three-dimensional polymeric units. The thermal stability of compounds was studied by thermal gravimetric analysis (TGA) and differential thermal analyses (DTA). PbS and PbO nano-structures were obtained by calcinations of the nano-structures of this coordination polymer at 600 °C

  6. Improving the Performance of PbS Quantum Dot Solar Cells by Optimizing ZnO Window Layer

    Science.gov (United States)

    Yang, Xiaokun; Hu, Long; Deng, Hui; Qiao, Keke; Hu, Chao; Liu, Zhiyong; Yuan, Shengjie; Khan, Jahangeer; Li, Dengbing; Tang, Jiang; Song, Haisheng; Cheng, Chun

    2017-04-01

    Comparing with hot researches in absorber layer, window layer has attracted less attention in PbS quantum dot solar cells (QD SCs). Actually, the window layer plays a key role in exciton separation, charge drifting, and so on. Herein, ZnO window layer was systematically investigated for its roles in QD SCs performance. The physical mechanism of improved performance was also explored. It was found that the optimized ZnO films with appropriate thickness and doping concentration can balance the optical and electrical properties, and its energy band align well with the absorber layer for efficient charge extraction. Further characterizations demonstrated that the window layer optimization can help to reduce the surface defects, improve the heterojunction quality, as well as extend the depletion width. Compared with the control devices, the optimized devices have obtained an efficiency of 6.7% with an enhanced V oc of 18%, J sc of 21%, FF of 10%, and power conversion efficiency of 58%. The present work suggests a useful strategy to improve the device performance by optimizing the window layer besides the absorber layer.

  7. Ligand-dependent exciton dynamics and photovoltaic properties of PbS quantum dot heterojunction solar cells.

    Science.gov (United States)

    Chang, Jin; Ogomi, Yuhei; Ding, Chao; Zhang, Yao Hong; Toyoda, Taro; Hayase, Shuzi; Katayama, Kenji; Shen, Qing

    2017-03-01

    The surface chemistry of colloidal quantum dots (QDs) plays an important role in determining the photoelectric properties of QD films and the corresponding quantum dot heterojunction solar cells (QDHSCs). To investigate the effects of the ligand structure on the photovoltaic performance and exciton dynamics of QDHSCs, PbS QDHSCs were fabricated by the solid state ligand exchange method with mercaptoalkanoic acid as the cross-linking ligand. Temperature-dependent photoluminescence and ultrafast transient absorption spectra show that the electronic coupling and charge transfer rate within QD ensembles were monotonically enhanced as the ligand length decreased. However, in practical QDHSCs, the second shortest ligand 3-mercaptopropionic acid (MPA) showed higher power conversion efficiency than the shortest ligand thioglycolic acid (TGA). This could be attributed to the difference in their surface trap states, supported by thermally stimulated current measurements. Moreover, compared with the non-conjugated ligand MPA, the conjugated ligand 4-mercaptobenzoic acid (MBA) introduces less trap states and has a similar charge transfer rate in QD ensembles, but has poor photovoltaic properties. This unexpected result could be contributed by the QD-ligand orbital mixing, leading to the charge transfer from QDs to ligands instead of charge transfer between adjacent QDs. This work highlights the significant effects of ligand structures on the photovoltaic properties and exciton dynamics of QDHSCs, which would shed light on the further development of QD-based photoelectric devices.

  8. Preschool Pathways to Science (PrePS[TM]): Facilitating Scientific Ways of Thinking, Talking, Doing, and Understanding

    Science.gov (United States)

    Gelman, Rochel; Brenneman, Kimberly; Macdonald, Gay; Roman, Moises

    2009-01-01

    To ensure they're meeting state early learning guidelines for science, preschool educators need fun, age-appropriate, and research-based ways to teach young children about scientific concepts. The basis for the PBS KIDS show "Sid the Science Kid," this teaching resource helps children ages 3-5 investigate their everyday world and develop the…

  9. Concepts, Operations, and Feasibility of a Projection-Based Variation Control System

    DEFF Research Database (Denmark)

    Stanciulescu, Stefan; Berger, Thorsten; Walkingshaw, Eric

    2016-01-01

    on a subset of all variants could ease the engineering of highly configurable software. We investigate the potential of one kind of such tools: projection-based variation control systems. For such systems we aim to understand: (i) what end-user operations they need to support, and (ii) whether they can...... realize the actual evolution of real-world, highly configurable software. We conduct an experiment that investigates variability-related evolution patterns and that evaluates the feasibility of a projection-based variation control system by replaying parts of the history of a highly configurable real......Highly configurable software often uses preproces- sor annotations to handle variability. However, understanding, maintaining, and evolving code with such annotations is difficult, mainly because a developer has to work with all variants at a time. Dedicated methods and tools that allow working...

  10. Data-driven fault detection for industrial processes canonical correlation analysis and projection based methods

    CERN Document Server

    Chen, Zhiwen

    2017-01-01

    Zhiwen Chen aims to develop advanced fault detection (FD) methods for the monitoring of industrial processes. With the ever increasing demands on reliability and safety in industrial processes, fault detection has become an important issue. Although the model-based fault detection theory has been well studied in the past decades, its applications are limited to large-scale industrial processes because it is difficult to build accurate models. Furthermore, motivated by the limitations of existing data-driven FD methods, novel canonical correlation analysis (CCA) and projection-based methods are proposed from the perspectives of process input and output data, less engineering effort and wide application scope. For performance evaluation of FD methods, a new index is also developed. Contents A New Index for Performance Evaluation of FD Methods CCA-based FD Method for the Monitoring of Stationary Processes Projection-based FD Method for the Monitoring of Dynamic Processes Benchmark Study and Real-Time Implementat...

  11. Implementation of a project-based engineering school: increasing student motivation and relevant learning

    Science.gov (United States)

    Terrón-López, María-José; García-García, María-José; Velasco-Quintana, Paloma-Julia; Ocampo, Jared; Vigil Montaño, María-Reyes; Gaya-López, María-Cruz

    2017-11-01

    The School of Engineering at Universidad Europea de Madrid (UEM) implemented, starting in the 2012-2013 period, a unified academic model based on project-based learning as the methodology used throughout the entire School. This model expects that every year, in each grade, all the students should participate in a capstone project integrating the contents and competencies of several courses. This paper presents the academic context under which this experience has been implemented, and a summary of the work done to design and implement the Project-Based Engineering School at the UEM. The steps followed, the structure used, some sample projects, as well as the difficulties and benefits of implementing the programme are discussed in this paper. The results are encouraging as students are more motivated and the initial set objectives were accomplished.

  12. Greenhouse gas emissions trading and project-based mechanisms. Proceedings - CATEP

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-01-01

    Greenhouse gas emissions trading and project-based mechanisms for greenhouse gas reduction are emerging market-based instruments for climate change policy. This book presents a selection of papers from an international workshop co-sponsored by the OECD and Concerted Action on Tradeable Emissions Permits (CATEP), to discuss key research and policy issues relating to the design and implementation of these instruments. The papers cover the experience of developing and transition countries with greenhouse gas emissions trading and project-based mechanisms. In addition, the papers examine the use of tradeable permits in policy mixes and harmonisation of emissions trading schemes, as well as transition issues relating to greenhouse gas emissions trading markets.

  13. Facilitating Adoption of Web Tools for Problem and Project Based Learning Activities

    DEFF Research Database (Denmark)

    Khalid, Md. Saifuddin; Rongbutsri, Nikorn; Buus, Lillian

    2012-01-01

    and project based learning. In the area of problem and project based learning, facilitation is the core term and the teacher often has the role as facilitator or moderator instead of a teacher teaching. Technology adoption for learning activities needs facilitation, which is mostly absent. Sustainable......This paper builds on research directions from ‘activity theory’ and ‘learning design’ to provide ‘facilitation’ for students standing within decision making related to selection of web 2.0 tools and university provided web-based applications for supporting students activities within problem...... adoption might be facilitated based on tool appropriation with activities associated with courses and projects. Our mapping of different tools in a framework is reported based on interviews, observations, narratives and survey. A direction towards facilitation process for adoption is discussed as part...

  14. A Social Contract for University-Industry Collaboration: A Case of Project-Based Learning Environment

    Science.gov (United States)

    Vartiainen, Tero

    This study determines a social contract for a form of university-industry collaboration to a project-based learning environment in close collaboration with industry. The author's previous studies on moral conflicts in a project-based learning (PjBL) environment and his 5-year engagement in the PjBL environment are used as background knowledge, and John Rawls' veil of ignorance is used as a method in the contract formulation. Fair and impartial treatment of actors is strived for with the contract which constitutes of sets of obligations for each party, students, clients, and university (instructors) in the chosen project course. With the contract fair and impartial treatment of actors is strived for and the most dilemmatic moral conflicts are tried to be avoided. The forming of the social contract is evaluated, and implications for research and collaborations in practice are offered.

  15. Measuring the influence of Cooperative Learning and Project Based Learning on problem solvin skill.

    OpenAIRE

    García Martín, Javier; Pérez Martínez, Jorge Enrique

    2011-01-01

    The aim of this study is to evaluate the effects obtained after applying two active learning methodologies (cooperative learning and project based learning) to the achievement of the competence problem solving. This study was carried out at the Technical University of Madrid, where these methodologies were applied to two Operating Systems courses. The first hypothesis tested was whether the implementation of active learning methodologies favours the achievement of ?problem solving?. The secon...

  16. Pengembangan Model Pembelajaran Project Based Learning pada Mata Kuliah Computer Aided Design

    Directory of Open Access Journals (Sweden)

    Satoto Endar Nayono

    2013-09-01

    Full Text Available One of the key competencies of graduates majoring in Civil Engineering and Planning Education, Faculty of Engineering, Yogyakarta State University (YSU is able to plan buildings. CAD courses aim to train students to be able to pour the planning concepts into the picture. One of the obstacles faced in the course are concepts and pictures that created by the students often do not correspond to the standards used in the field. This study aims to develop a model of project-based learning so that the students’ pictures are more in line with the actual conditions in the field. This study was carried out through the stages as follows: (1 Pre test, (2 Planning of learning, (3 Implementation of the learning model of project-based learning, (4 monitoring and evaluation (5 Reflection and revision, (6 Implementation of learning in the next cycle, and (7 Evaluation of the learning outcomes. This study was conducted for four months in 2012 in the Department of Civil Engineering and Planning Education, Faculty of Engineering, YSU. The subjects of this study are the students who took the course of Computer Aided Design. The analysis of the data used descriptive qualitative and descriptive statistics. The results of this study were: (1 The implementation of project based learning model was proven to increase the learning process and the learning outcomes of students in the subject of CAD through the provision of buildings planning pictures tasks of school buildings based on the real conditions in the field. The task was delivered in every meeting and improved based on the feedback from their lecturers, (2 the learning model of project based learning will be easier to be implemented if it is accompanied by the model of peer tutoring and the learning model of PAIKEM.

  17. Outward knowledge transfer: the impact of project-based organization on performance

    OpenAIRE

    Ulrich Lichtenthaler

    2010-01-01

    Recently, interfirm knowledge transactions have increased although many firms experience major managerial difficulties in outward knowledge transfer, e.g. technology licensing. To reduce the traditional underemphasis on empirical research into corporate outward knowledge transfer, we use data from 152 firms to test four hypotheses relating firms' outward knowledge transfer performance to two types of project-based organization, which complement formal and informal organizational structures: p...

  18. Profile of Students' Creative Thinking Skills on Quantitative Project-Based Protein Testing using Local Materials

    Directory of Open Access Journals (Sweden)

    D. K. Sari

    2017-04-01

    Full Text Available The purpose of this study is to obtain a profile of students’ creative thinking skills on quantitative project-based protein testing using local materials. Implementation of the research is using quasi-experimental method pre-test post-test control group design with 40 students involved in Biochemistry lab. The research instrument is pre-test and post-test using creative thinking skills in the form of description and students’ questionnaire. The analysis was performed with SPSS 22.0 program to see the significance normality, U Mann-Whitney test for nonparametric statistics, N-Gain score, and the percentage of student responses to the practicum performed. The research result shows that the pretest rate in the experimental group is 8.25 while in the control group is 6.90. After attending a project-based practicum with local materials, the experimental group obtained the mean of posttest is 37.55 while in control class is 11.18. The students’ improvement on creative thinking skills can be seen from the average of N-Gain in the experimental class with 0.32 (medium category and in the control category with 0.05 (low category. The experimental and control class have different creative thinking skills significantly different fluency, flexibility, novelty, and detail. It can be concluded that quantitative project-based protein testing using local materials can improve students’ creative thinking skills. 71% of total students feel that quantitative project-based protein testing using local materials make them more creative in doing a practicum in the laboratory.

  19. Towards a project-based service delivery approach : Uncovering organisational tensions

    OpenAIRE

    12330841 - Van der Waldt, Gerrit

    2009-01-01

    In line with the modernizing, re-inventing and alternative service delivery paradigm, governments increasingly utilise project-based methodologies to improve service delivery. There is general agreement that projects are becoming increasingly important for government institutions to operationalise strategic objectives and policy programmes. This approach is commonly known as ‗Management-by-Projects‘. To adopt this approach requires of public institutions to adjust their existing structures...

  20. Implementing CDIO project-based learning in training of Heat and Power engineers

    Science.gov (United States)

    Boiko, E. A.; Shishmarev, P. V.; Karabarin, D. I.; Yanov, S. R.; Pikalova, A. A.

    2017-11-01

    This paper presents the experience and current results of CDIO standards implementation in training of bachelors in Heat and Power Engineering at Thermal Power Stations academic department in Siberian Federal University. It provides information on methodology of modernization of educational programs, curricula and programs of disciplines in transition to CDIO project-based learning technology. Preliminary assessment and analysis of lessons learned and scaling perspectives are given.

  1. The Use of ICT Platforms to Promote Knowledge Exchange in Project-Based Organisations

    OpenAIRE

    Priyono Anjar

    2016-01-01

    This study aims to investigate the use of information and communication technology (ICT) to support knowledge exchange in project-based organisations. The primary ICT tool investigated in this research is WhatsApp, a messaging application that has been widely used since its introduction. An ethnographic case study method was utilised to analyse qualitative data collected from interviews and focus group discussions. Three projects in an Indonesian university with a duration ranging from 8 mont...

  2. Biotechnology by Design: An Introductory Level, Project-Based, Synthetic Biology Laboratory Program for Undergraduate Students†

    OpenAIRE

    Beach, Dale L.; Alvarez, Consuelo J.

    2015-01-01

    Synthetic biology offers an ideal opportunity to promote undergraduate laboratory courses with research-style projects, immersing students in an inquiry-based program that enhances the experience of the scientific process. We designed a semester-long, project-based laboratory curriculum using synthetic biology principles to develop a novel sensory device. Students develop subject matter knowledge of molecular genetics and practical skills relevant to molecular biology, recombinant DNA techniq...

  3. Evaluation of a Team Project Based Learning Module for Developing Employability Skills

    OpenAIRE

    Janice Whatley

    2012-01-01

    This paper presents a case study, in which a new module, aimed at enhancing students’ employ-ability skills, is evaluated. Employability skills for graduates from higher education are regarded as essential outcomes from their degree programmes, but it can be difficult to provide appropriate opportunities to develop these skills in the context of their studies. This paper describes a new module, called Live Projects, designed to provide project based learning on campus, but involv-ing local bu...

  4. Problem and Project Based Learning in Hybrid Spaces:Nomads and Artisans

    OpenAIRE

    Ryberg, Thomas; Davidsen, Jacob; Hodgson, Vivien

    2016-01-01

    There is a need within networked learning to understand and conceptualise the interplay between digital and physical spaces or what we could term hybrid spaces. Therefore, we discuss a recent study of students from two different programmes who are engaged in long-term, group-based problem and project based learning. Based on interviews, workshops and observations of students’ actual group practices in open, shared and flexible spaces in Aalborg University (AAU), we identify and discuss how st...

  5. Design of retinal-projection-based near-eye display with contact lens.

    Science.gov (United States)

    Wu, Yuhang; Chen, Chao Ping; Mi, Lantian; Zhang, Wenbo; Zhao, Jingxin; Lu, Yifan; Guo, Weiqian; Yu, Bing; Li, Yang; Maitlo, Nizamuddin

    2018-04-30

    We propose a design of a retinal-projection-based near-eye display for achieving ultra-large field of view, vision correction, and occlusion. Our solution is highlighted by a contact lens combo, a transparent organic light-emitting diode panel, and a twisted nematic liquid crystal panel. Its design rules are set forth in detail, followed by the results and discussion regarding the field of view, angular resolution, modulation transfer function, contrast ratio, distortion, and simulated imaging.

  6. The Student's Scientific Attitude and Creativity of Product in Environmental Issues Through Project Based Learning

    OpenAIRE

    Yustina, Yustina; Suwondo, Suwondo

    2015-01-01

    The purpose of this research was to got the information about student's scientific attitude and creativity of product and correlation both of it in enviromental issues through project based learning. This research was conducted from January to June 2015. Sample in this research were 34 students of 2014 grade in FKIP Biologi UR used parameters were (1) scientific attitude with 4 indicators (curiosity, cooperative, carefulness and discipline); (2) creativity of product. Observation instrument m...

  7. Real-Time Projection-Based Augmented Reality System for Dynamic Objects in the Performing Arts

    Directory of Open Access Journals (Sweden)

    Jaewoon Lee

    2015-02-01

    Full Text Available This paper describes the case study of applying projection-based augmented reality, especially for dynamic objects in live performing shows, such as plays, dancing, or musicals. Our study aims to project imagery correctly inside the silhouettes of flexible objects, in other words, live actors or the surface of actor’s costumes; the silhouette transforms its own shape frequently. To realize this work, we implemented a special projection system based on the real-time masking technique, that is to say real-time projection-based augmented reality system for dynamic objects in performing arts. We installed the sets on a stage for live performance, and rehearsed particular scenes of a musical. In live performance, using projection-based augmented reality technology enhances technical and theatrical aspects which were not possible with existing video projection techniques. The projected images on the surfaces of actor’s costume could not only express the particular scene of a performance more effectively, but also lead the audience to an extraordinary visual experience.

  8. PENGEMBANGAN TUGAS AKHIR MELALUI PROJECT BASED LEARNING MODEL UNTUK MENINGKATKAN GENERIC GREEN SKILLS SISWA

    Directory of Open Access Journals (Sweden)

    Ana Ana

    2015-02-01

    Full Text Available ABSTRACT The development of students’ final project through Project-based Learning (PBLapproach was conducted in the workshop of family resource management (FRM in 7th semester.PBL approach is expected to give contribution to students’ motivation and experience to finish their final assignments of FRM workshop. The objectives of the research are to: (1 develop PBL model for the students’final project; (2 produce learning instruments of PBL such as lesson plans, manual of FRM workshop, and scientific report of FRM workshop. The method of the study was using research and development of Plomp model and quasi experiment for testing the effectiveness of the model. The research subjects were the students from the class of 2009 and 2010 who joined FRM workshop course. The study produced model, lesson plans, and manual of FRM workshop as the outputs. The result showed that project based learning model was effective to improve the students’ generic green skills for project management, collaborative skills, and communicative competence. Keywords: final project, generic green skill, family resource management, Project-Based Learning

  9. Incorporation of project-based learning into an occupational health course.

    Science.gov (United States)

    Dehdashti, Alireza; Mehralizadeh, Semira; Kashani, Masoud Motalebi

    2013-01-01

    Use of an appropriate teaching approach is a major concern for faculty members who are involved in occupational health and safety academic education. The challenge is to explore teaching tools to equip students with knowledge and skills to prepare them for their practices, in which they will encounter occupational health and safety issues in various occupational settings. The current study presents the design and implementation of a team project-based learning approach for undergraduate occupational health students to examine the appropriateness and perceptions of students and educators with regard to such a learning experience. Steps were taken to guide the educators and students through the learning process based on projects completed in teams. The research tools for collecting data were a questionnaire and semi-structured interviews with participants. The results illustrated that use of the proposed teaching approach as part of occupational health education may have the potential to motivate and enhance the active roles of educators and students in the learning process, and improve students' technical and social skills that are crucial for practice in the occupational health field. The study findings showed that project-based learning may provide a promising teaching strategy in the education and training of occupational health students. In addition, academic institutions should encourage educators to plan, introduce and evaluate the effectiveness of project-based learning.

  10. The implementation of Project-Based Learning in courses Audio Video to Improve Employability Skills

    Science.gov (United States)

    Sulistiyo, Edy; Kustono, Djoko; Purnomo; Sutaji, Eddy

    2018-04-01

    This paper presents a project-based learning (PjBL) in subjects with Audio Video the Study Programme Electro Engineering Universitas Negeri Surabaya which consists of two ways namely the design of the prototype audio-video and assessment activities project-based learning tailored to the skills of the 21st century in the form of employability skills. The purpose of learning innovation is applying the lab work obtained in the theory classes. The PjBL aims to motivate students, centering on the problems of teaching in accordance with the world of work. Measures of learning include; determine the fundamental questions, designs, develop a schedule, monitor the learners and progress, test the results, evaluate the experience, project assessment, and product assessment. The results of research conducted showed the level of mastery of the ability to design tasks (of 78.6%), technical planning (39,3%), creativity (42,9%), innovative (46,4%), problem solving skills (the 57.1%), skill to communicate (75%), oral expression (75%), searching and understanding information (to 64.3%), collaborative work skills (71,4%), and classroom conduct (of 78.6%). In conclusion, instructors have to do the reflection and make improvements in some of the aspects that have a level of mastery of the skills less than 60% both on the application of project-based learning courses, audio video.

  11. The development of thematic materials using project based learning for elementary school

    Science.gov (United States)

    Yuliana, M.; Wiryawan, S. A.; Riyadi

    2018-05-01

    Teaching materials is one of the important factors in supporting on learning process. This paper discussed about developing thematic materials using project based learning. Thematic materials are designed to make students to be active, creative, cooperative, easy in thinking to solve the problem. The purpose of the research was to develop thematic material using project based learning which used valid variables. The method of research which used in this research was four stages of research and development proposed by Thiagarajan consisting of 4 stages, namely: (1) definition stage, (2) design stage, (3) development stage, and (4) stage of dissemination. The first stage was research and information collection, it was in form of need analysis with questionnaire, observation, interview, and document analysis. Design stage was based on the competencies and indicator. The third was development stage, this stage was used to product validation from expert. The validity of research development involved media validator, material validator, and linguistic validator. The result from the validation of thematic material by expert showed that the overall result had a very good rating which ranged from 1 to 5 likert scale, media validation showed a mean score 4,83, the material validation showed mean score 4,68, and the mean of linguistic validation was e 4,74. It showed that the thematic material using project based learning was valid and feasible to be implemented in the context thematic learning.

  12. An early start to STEM education among year 1 primary students through project-based inquiry learning in the context of a magnet

    Science.gov (United States)

    Safiee, N.; Jusoh, Z. M.; Noor, A. M. H. M.; Tek, O. E.; Salleh, S. M.

    2018-01-01

    For the needs of the 21st century, the Government of Malaysia has conceptualized the Malaysia Education Blueprint 2013-2025 which embodies 11 strategic and operational shifts. In Shift 1, it is emphasized that the quality of Science, Technology, Engineering, and Mathematics (STEM) Education will be enhanced. This study employed the mixed-method approach using the “one-group pre-test and post-test design”. Accordingly, this paper describes the pedagogical practice of Project-based Inquiry Learning (PIL) which promotes STEM Education among Year 1 students in the move to progress in tandem with Shift 1. Specifically, using the context of a magnet which has been stipulated in the Primary School Standard Curriculum, Year 1 students experienced the STEM Education through the STEM Pedagogy in which they raised questions upon the presentation of a relevant stimulus (Inquiry Phase), explored the ways in which a train carriage or coach could be assembled by means of recycled materials and magnets (Exploration Phase), designed a train carriage (Design Phase), and ultimately reflected on their inventions (Reflection Phase). The cognitive and affective impacts through the use of this Project-based Inquiry Learning are presented. Implications for the teaching and learning of science are discussed within the context of STEM Education.

  13. A Pilot Study: Facilitating Cross-Cultural Understanding with Project-Based Collaborative Learning in an Online Environment

    Science.gov (United States)

    Shadiev, Rustam; Hwang, Wu-Yuin; Huang, Yueh-Min

    2015-01-01

    This study investigated three aspects: how project-based collaborative learning facilitates cross-cultural understanding; how students perceive project-based collaborative learning implementation in a collaborative cyber community (3C) online environment; and what types of communication among students are used. A qualitative case study approach…

  14. 76 FR 33333 - Use of Small Area Fair Market Rents for Project Base Vouchers in the Dallas TX Metropolitan Area

    Science.gov (United States)

    2011-06-08

    ... DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT [Docket No. FR-5525-N-01] Use of Small Area Fair Market Rents for Project Base Vouchers in the Dallas TX Metropolitan Area AGENCY: Office of the Assistant... Small Area Fair Market Rents (SAFMRs) for Project-Based Vouchers (PBVs) located in the Dallas, TX...

  15. Linking project-based production and project management temporary systems in multiple contexts : An introduction to the special edition

    NARCIS (Netherlands)

    Oerlemans, L.A.G.; Pretorius, M.W.

    2014-01-01

    As organisations in more and more industries look for flexible ways of production in the wake of rapidly changing market environments, project-based organising is becoming an increasingly important mode of organisation (Eisenhardt & Tabrizi, 1995). Whereas project-based organisation was

  16. Cognitive and Socio-Affective Outcomes of Project-Based Learning: Perceptions of Greek Second Chance School Students

    Science.gov (United States)

    Koutrouba, Konstantina; Karageorgou, Elissavet

    2013-01-01

    The present questionnaire-based study was conducted in 2010 in order to examine 677 Greek Second Chance School (SCS) students' perceptions about the cognitive and socio-affective outcomes of project-based learning. Data elaboration, statistical and factor analysis showed that the participants found that project-based learning offered a second…

  17. Teaching Power Electronics with a Design-Oriented, Project-Based Learning Method at the Technical University of Denmark

    Science.gov (United States)

    Zhang, Zhe; Hansen, Claus Thorp; Andersen, Michael A. E.

    2016-01-01

    Power electronics is a fast-developing technology within the electrical engineering field. This paper presents the results and experiences gained from applying design-oriented project-based learning to switch-mode power supply design in a power electronics course at the Technical University of Denmark (DTU). Project-based learning (PBL) is known…

  18. Improving charge transport in PbS quantum Dot to Al:ZnO layer by changing the size of Quantum dots in hybrid solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Mehrabian, Masood [Maragheh Univ. (Iran, Islamic Republic of). Faculty of Basic Science; Abdollahian, Parinaz [Maragheh Univ. (Iran, Islamic Republic of). Dept. of Materials Engineering

    2016-07-01

    PbS Quantum dots and P3HT are promising materials for photovoltaic applications due to their absorption in the NIR and visible region, respectively. Our previous experimental work showed that doping Al to ZnO lattice (Al:ZnO) could efficiently improve the cell performance. In this article, hybrid solar cells containing of two active areas with ITO/Al:ZnO/PbS QDs/P3HT and PCBM/Ag structure were fabricated and the effect of PbS QD size on photovoltaic properties was investigated. Optimised solar cell showed maximum power conversion efficiency of 2.45 % with short-circuit current of 9.36 mA/cm{sup 2} and open-circuit voltage of 0.59 V under 1 sun illumination (AM1.5).

  19. Tunable and switchable all-fiber comb filter using a PBS-based two-stage cascaded Mach-Zehnder interferometer

    Science.gov (United States)

    Luo, Zhi-Chao; Luo, Ai-Ping; Xu, Wen-Cheng

    2011-08-01

    We propose and demonstrate a novel tunable and switchable all-fiber comb filter by employing a polarization beam splitter (PBS)-based two-stage cascaded Mach-Zehnder (M-Z) interferometer. The proposed comb filter consists of a rotatable polarizer, a fiber PBS, a non-3-dB coupler and a 3-dB coupler. By simply adjusting the polarization state of the input light, the dual-function of channel spacing tunable and wavelength switchable (interleaving) operations can be efficiently obtained. The theoretical analysis is verified by the experimental results. A comb filter with both the channel spacing tunable from 0.18 nm to 0.36 nm and the wavelength switchable functions is experimentally demonstrated.

  20. Quantum confinement-tunable ultrafast charge transfer at the PbS quantum dot and phenyl-C61-butyric acid methyl ester interface

    KAUST Repository

    El-Ballouli, AlA'A O.; Alarousu, Erkki Antero; Bernardi, Marco; Aly, Shawkat Mohammede; Lagrow, Alec P.; Bakr, Osman; Mohammed, Omar F.

    2014-01-01

    Quantum dot (QD) solar cells have emerged as promising low-cost alternatives to existing photovoltaic technologies. Here, we investigate charge transfer and separation at PbS QDs and phenyl-C61-butyric acid methyl ester (PCBM) interfaces using a combination of femtosecond broadband transient absorption (TA) spectroscopy and steady-state photoluminescence quenching measurements. We analyzed ultrafast electron injection and charge separation at PbS QD/PCBM interfaces for four different QD sizes and as a function of PCBM concentration. The results reveal that the energy band alignment, tuned by the quantum size effect, is the key element for efficient electron injection and charge separation processes. More specifically, the steady-state and time-resolved data demonstrate that only small-sized PbS QDs with a bandgap larger than 1 eV can transfer electrons to PCBM upon light absorption. We show that these trends result from the formation of a type-II interface band alignment, as a consequence of the size distribution of the QDs. Transient absorption data indicate that electron injection from photoexcited PbS QDs to PCBM occurs within our temporal resolution of 120 fs for QDs with bandgaps that achieve type-II alignment, while virtually all signals observed in smaller bandgap QD samples result from large bandgap outliers in the size distribution. Taken together, our results clearly demonstrate that charge transfer rates at QD interfaces can be tuned by several orders of magnitude by engineering the QD size distribution. The work presented here will advance both the design and the understanding of QD interfaces for solar energy conversion. © 2014 American Chemical Society.

  1. Immune modulating effects of NKT cells in a physiologically low dose Leishmania major infection model after αGalCer analog PBS57 stimulation.

    Science.gov (United States)

    Griewank, Klaus G; Lorenz, Beate; Fischer, Michael R; Boon, Louis; Lopez Kostka, Susanna; von Stebut, Esther

    2014-06-01

    Leishmaniasis is a parasitic infection affecting ∼12 million people worldwide, mostly in developing countries. Treatment options are limited and no effective vaccines exist to date. Natural Killer T (NKT) cells are a conserved innate-like lymphocyte population with immunomodulating effects in various settings. A number of reports state a role of NKT cells in different models of Leishmania infection. Here, we investigated the effect of NKT cells in a physiologically relevant, intradermal low dose infection model. After inoculation of 103 infectious-stage L. major, comparable numbers of skin-immigrating NKT cells in both susceptible BALB/c mice and resistant C57BL/6 mice were noted. Compared to their wild type counterparts, NKT cell-deficient mice on a C57BL/6 background were better able to contain infection with L. major and showed decreased IL-4 production in cytokine analysis performed 5 and 8 weeks after infection. Low doses of the NKT cell stimulating αGalCer analog PBS57 applied at the time of infection led to disease exacerbation in C57BL/6 wild-type, but not NKT-deficient mice. The effect was dependent both on the timing and amount of PBS57 administered. The effect of NKT cell stimulation by PBS57 proved to be IL-4 dependent, as it was neutralized in IL-4-deficient C57BL/6 or anti-IL-4 antibody-treated wild-type mice. In contrast to C57BL/6 mice, administration of PBS57 in susceptible BALB/c mice resulted in an improved course of disease. Our results reveal a strain- and cytokine-dependent regulatory role of NKT cells in the development of immunity to low dose L. major infections. These effects, probably masked in previous studies using higher parasite inocula, should be considered in future therapy and immunization approaches.

  2. Efficiency enhancement of solid-state PbS quantum dot-sensitized solar cells with Al2O3 barrier layer

    KAUST Repository

    Brennan, Thomas P.; Trejo, Orlando; Roelofs, Katherine E.; Xu, John; Prinz, Fritz B.; Bent, Stacey F.

    2013-01-01

    Atomic layer deposition (ALD) was used to grow both PbS quantum dots and Al2O3 barrier layers in a solid-state quantum dot-sensitized solar cell (QDSSC). Barrier layers grown prior to quantum dots resulted in a near-doubling of device efficiency (0.30% to 0.57%) whereas barrier layers grown after quantum dots did not improve efficiency, indicating the importance of quantum dots in recombination processes. © 2013 The Royal Society of Chemistry.

  3. Quantum confinement-tunable ultrafast charge transfer at the PbS quantum dot and phenyl-C61-butyric acid methyl ester interface

    KAUST Repository

    El-Ballouli, AlA'A O.

    2014-05-14

    Quantum dot (QD) solar cells have emerged as promising low-cost alternatives to existing photovoltaic technologies. Here, we investigate charge transfer and separation at PbS QDs and phenyl-C61-butyric acid methyl ester (PCBM) interfaces using a combination of femtosecond broadband transient absorption (TA) spectroscopy and steady-state photoluminescence quenching measurements. We analyzed ultrafast electron injection and charge separation at PbS QD/PCBM interfaces for four different QD sizes and as a function of PCBM concentration. The results reveal that the energy band alignment, tuned by the quantum size effect, is the key element for efficient electron injection and charge separation processes. More specifically, the steady-state and time-resolved data demonstrate that only small-sized PbS QDs with a bandgap larger than 1 eV can transfer electrons to PCBM upon light absorption. We show that these trends result from the formation of a type-II interface band alignment, as a consequence of the size distribution of the QDs. Transient absorption data indicate that electron injection from photoexcited PbS QDs to PCBM occurs within our temporal resolution of 120 fs for QDs with bandgaps that achieve type-II alignment, while virtually all signals observed in smaller bandgap QD samples result from large bandgap outliers in the size distribution. Taken together, our results clearly demonstrate that charge transfer rates at QD interfaces can be tuned by several orders of magnitude by engineering the QD size distribution. The work presented here will advance both the design and the understanding of QD interfaces for solar energy conversion. © 2014 American Chemical Society.

  4. Real-Time Observation of Ultrafast Intraband Relaxation and Exciton Multiplication in PbS Quantum Dots

    KAUST Repository

    El-Ballouli, Ala’a O.

    2014-03-19

    We examine ultrafast intraconduction band relaxation and multiple-exciton generation (MEG) in PbS quantum dots (QDs) using transient absorption spectroscopy with 120 fs temporal resolution. The intraconduction band relaxation can be directly and excellently resolved spectrally and temporally by applying broadband pump-probe spectroscopy to excite and detect the wavelengths around the exciton absorption peak, which is located in the near-infrared region. The time-resolved data unambiguously demonstrate that the intraband relaxation time progressively increases as the pump-photon energy increases. Moreover, the relaxation time becomes much shorter as the size of the QDs decreases, indicating the crucial role of spatial confinement in the intraband relaxation process. Additionally, our results reveal the systematic scaling of the intraband relaxation time with both excess energy above the effective energy band gap and QD size. We also assess MEG in different sizes of the QDs. Under the condition of high-energy photon excitation, which is well above the MEG energy threshold, ultrafast bleach recovery due to the nonradiative Auger recombination of the multiple electron-hole pairs provides conclusive experimental evidence for the presence of MEG. For instance, we achieved quantum efficiencies of 159, 129 and 106% per single-absorbed photon at pump photoexcition of three times the band gap for QDs with band gaps of 880 nm (1.41 eV), 1000 nm (1.24 eV) and 1210 nm (1.0 eV), respectively. These findings demonstrate clearly that the efficiency of transferring excess photon energy to carrier multiplication is significantly increased in smaller QDs compared with larger ones. Finally, we discuss the Auger recombination dynamics of the multiple electron-hole pairs as a function of QD size.

  5. Efficacy of In2S3 interfacial recombination barrier layer in PbS quantum-dot-sensitized solar cells

    International Nuclear Information System (INIS)

    Basit, Muhammad Abdul; Abbas, Muhammad Awais; Bang, Jin Ho; Park, Tae Joo

    2015-01-01

    In 2 S 3 interfacial recombination barrier layer (IBL) via successive ionic layer adsorption and reaction (SILAR) was successfully employed between PbS quantum dots and mesoporous TiO 2 in quantum-dot-sensitized solar cells (QDSSCs). In 2 S 3 IBL significantly increased the resistance against back electron transfer from TiO 2 , resulting an increment in the photocurrent density (J SC ) for the cell with single SILAR cycle of In 2 S 3 IBL. Further increase in the number of SILAR cycles of In 2 S 3 IBL deteriorated the J SC , whereas open-circuit voltage sustained the increasing trend. Therefore, an optimal photo-conversion efficiency of ∼2.2% was obtained for the cell with 2 SILAR cycles of In 2 S 3 IBL, which strategically reached a value of ∼2.70% after annealing (increased by 40% compared to the control cell without IBL). In 2 S 3 IBL not only improved the recombination resistance and electron life time of the cells, but it also enhanced the photostability of the cells. - Highlights: • In 2 S 3 interfacial recombination barrier layer was deposited on TiO 2 photoanode via SILAR process. • Resistance against back electron transfer from TiO 2 (recombination) increased notably. • Fabricated PbS-QDSSCs were characterized using IPCE, OCVD and EIS techniques. • In 2 S 3 IBL improved chemical capacitance, electron life time and photostability of modified cells. • 2In 2 S 3 IBL showed optimal performance, yielding 40% improvement in PCE after heat treatment.

  6. TH-CD-209-01: A Greedy Reassignment Algorithm for the PBS Minimum Monitor Unit Constraint

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y; Kooy, H; Craft, D; Depauw, N; Flanz, J; Clasie, B [Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States)

    2016-06-15

    Purpose: To investigate a Greedy Reassignment algorithm in order to mitigate the effects of low weight spots in proton pencil beam scanning (PBS) treatment plans. Methods: To convert a plan from the treatment planning system’s (TPS) to a deliverable plan, post processing methods can be used to adjust the spot maps to meets the minimum MU constraint. Existing methods include: deleting low weight spots (Cut method), or rounding spots with weight above/below half the limit up/down to the limit/zero (Round method). An alternative method called Greedy Reassignment was developed in this work in which the lowest weight spot in the field was removed and its weight reassigned equally among its nearest neighbors. The process was repeated with the next lowest weight spot until all spots in the field were above the MU constraint. The algorithm performance was evaluated using plans collected from 190 patients (496 fields) treated at our facility. The evaluation criteria were the γ-index pass rate comparing the pre-processed and post-processed dose distributions. A planning metric was further developed to predict the impact of post-processing on treatment plans for various treatment planning, machine, and dose tolerance parameters. Results: For fields with a gamma pass rate of 90±1%, the metric has a standard deviation equal to 18% of the centroid value. This showed that the metric and γ-index pass rate are correlated for the Greedy Reassignment algorithm. Using a 3rd order polynomial fit to the data, the Greedy Reassignment method had 1.8 times better metric at 90% pass rate compared to other post-processing methods. Conclusion: We showed that the Greedy Reassignment method yields deliverable plans that are closest to the optimized-without-MU-constraint plan from the TPS. The metric developed in this work could help design the minimum MU threshold with the goal of keeping the γ-index pass rate above an acceptable value.

  7. Affordances of students' using the World Wide Web as a publishing medium in project-based learning environments

    Science.gov (United States)

    Bos, Nathan Daniel

    This dissertation investigates the emerging affordance of the World Wide Web as a place for high school students to become authors and publishers of information. Two empirical studies lay groundwork for student publishing by examining learning issues related to audience adaptation in writing, motivation and engagement with hypermedia, design, problem-solving, and critical evaluation. Two models of student publishing on the World Wide Web were investigated over the course of two 11spth grade project-based science curriculums. In the first curricular model, students worked in pairs to design informative hypermedia projects about infectious diseases that were published on the Web. Four case studies were written, drawing on both product- and process-related data sources. Four theoretically important findings are illustrated through these cases: (1) multimedia, especially graphics, seemed to catalyze some students' design processes by affecting the sequence of their design process and by providing a connection between the science content and their personal interest areas, (2) hypermedia design can demand high levels of analysis and synthesis of science content, (3) students can learn to think about science content representation through engagement with challenging design tasks, and (4) students' consideration of an outside audience can be facilitated by teacher-given design principles. The second Web-publishing model examines how students critically evaluate scientific resources on the Web, and how students can contribute to the Web's organization and usability by publishing critical reviews. Students critically evaluated Web resources using a four-part scheme: summarization of content, content, evaluation of credibility, evaluation of organizational structure, and evaluation of appearance. Content analyses comparing students' reviews and reviewed Web documents showed that students were proficient at summarizing content of Web documents, identifying their publishing

  8. Modification of Morphological, Structural and Optical Properties of CBD-Based Growth of PbS Films on Glass Substrates by Addition of Saccharin

    Directory of Open Access Journals (Sweden)

    Yasin YÜCEL

    2018-03-01

    Full Text Available Saccharin which so-called as benzoic sulfimide is an artificial sweetener. In this paper, nanostructured lead sulfide (PbS thin films were produced in the presence of additive known as saccharin via chemical bath deposition (CBD. Effect of the saccharin content on the morphological, optical and structural properties of the films has been investigated. Lead sulfide (PbS films that included additive were prepared at five different concentrations of saccharin (from 0 to 5%. The fabricated samples were characterized by surface roughness, scanning electron microscopy (SEM, X-Ray diffraction and UV-vis spectroscopy. It was found that the presence of saccharin highly affected the optical and structural properties of PbS thin films. According to the X-Ray diffraction results, crystallite size values of the films decreased from 12.88 to 5.25 nm with increasing of saccharin content. UV-vis measurements showed that both the band gap and transmission properties of the films increased as a result of increasing saccharin concentration. Further, Surface roughness measurements exhibited that average surface roughness was diminished with increasing saccharin content. As a result, it has been found that the presence of saccharin in growth solution played a significant mission in adjusting the main physical properties of the samples.

  9. Developing a project-based computational physics course grounded in expert practice

    Science.gov (United States)

    Burke, Christopher J.; Atherton, Timothy J.

    2017-04-01

    We describe a project-based computational physics course developed using a backwards course design approach. From an initial competency-based model of problem solving in computational physics, we interviewed faculty who use these tools in their own research to determine indicators of expert practice. From these, a rubric was formulated that enabled us to design a course intended to allow students to learn these skills. We also report an initial implementation of the course and, by having the interviewees regrade student work, show that students acquired many of the expert practices identified.

  10. Integrating Creativity Training into Problem and Project-Based Learning (PBL) Curriculum in Engineering Education

    DEFF Research Database (Denmark)

    Zhou, Chunfang

    2012-01-01

    In order to foster creative engineers, a creativity training programme was carried out in medialogy education in a Problem and Project-Based Learning (PBL) environment at Aalborg University, Denmark. This paper focuses on the question of how engineering students perceive the strategy of integrating...... creativity training into a PBL curriculum. A total of 20 medialogy students in the training programme were interviewed. The data shows that the training programme was thought useful and students get benefits such as gaining project work skills, creative concepts and confidence of being creative. However...

  11. Project-based physics labs using low-cost open-source hardware

    Science.gov (United States)

    Bouquet, F.; Bobroff, J.; Fuchs-Gallezot, M.; Maurines, L.

    2017-03-01

    We describe a project-based physics lab, which we proposed to third-year university students. These labs are based on new open-source low-cost equipment (Arduino microcontrollers and compatible sensors). Students are given complete autonomy: they develop their own experimental setup and study the physics topic of their choice. The goal of these projects is to let students to discover the reality of experimental physics. Technical specifications of the acquisition material and case studies are presented for practical implementation in other universities.

  12. Organizational Enablers for Project Governance and Governmentality in Project-based Organizations

    DEFF Research Database (Denmark)

    Pemsel, Sofia; Müller, Ralf; Shao, Jingting

    for governmentality belong mainly to the cultural-cognitive pillar. Collectively these OEs provide for an ambidexterity of flexibility and stability, which allows organizations to align their internal characteristics with their organizational context. Managerial and theoretical implications of the results......This study identifies organizational enablers (OEs) for governance and governmentality in the realm of projects in project-based organizations (PBOs). We use a multiple case study design with six firms in Sweden and China to identify OEs. Institutional theory serves as theoretical perspective...

  13. Organizational Enablers for Project Governance and Governmentality in Project-based Organizations

    DEFF Research Database (Denmark)

    Müller, Ralf; Pemsel, Sofia; Shao, Jingting

    2015-01-01

    for governmentality belong mainly to the cultural–cognitive pillar. Collectively these OEs provide for an ambidexterity of flexibility and stability, which allows organizations to align their internal characteristics with their organizational context. Managerial and theoretical implications of the results......This study identifies organizational enablers (OEs) for governance and governmentality in the realm of projects in project-based organizations (PBOs). We use a multiple case study design with six firms in Sweden and China to identify OEs. Institutional theory serves as theoretical perspective...

  14. Gender and Diversity in a Problem and Project Based Learning Environment

    DEFF Research Database (Denmark)

    Du, Xiangyun

    Problem and Project Based Learning (PBL) has been well used as an educational philosophy and methodology in the construction of student centered and contextualized learning environment. PBL is also regarded as an effective method in producing engineering graduates who can not only meet the needs...... on the learning experiences of engineering students in the PBL environment in Denmark. This book also attempts to question the issue of diversity in engineering education via the exploration of whether or in which ways the PBL environment is friendly to diverse groups of learners such as women....

  15. Professor Eric Can't See: A Project-Based Learning Case for Neurobiology Students.

    Science.gov (United States)

    Ogilvie, Judith Mosinger; Ribbens, Eric

    2016-01-01

    "Professor Eric Can't See" is a semi-biographical case study written for an upper level undergraduate Neurobiology of Disease course. The case is integrated into a unit using a project-based learning approach to investigate the retinal degenerative disorder Retinitis pigmentosa and the visual system. Some case study scenes provide specific questions for student discussion and problem-based learning, while others provide background for student inquiry and related active learning exercises. The case was adapted from "'Chemical Eric' Can't See," and could be adapted for courses in general neuroscience or sensory neuroscience.

  16. Designing “Theory of Machines and Mechanisms” course on Project Based Learning approach

    DEFF Research Database (Denmark)

    Shinde, Vikas

    2013-01-01

    by the industry and the learning outcomes specified by the National Board of Accreditation (NBA), India; this course is restructured on Project Based Learning approach. A mini project is designed to suit course objectives. An objective of this paper is to discuss the rationale of this course design......Theory of Machines and Mechanisms course is one of the essential courses of Mechanical Engineering undergraduate curriculum practiced at Indian Institute. Previously, this course was taught by traditional instruction based pedagogy. In order to achieve profession specific skills demanded...... and the process followed to design a project which meets diverse objectives....

  17. BRDF-dependent accuracy of array-projection-based 3D sensors.

    Science.gov (United States)

    Heist, Stefan; Kühmstedt, Peter; Tünnermann, Andreas; Notni, Gunther

    2017-03-10

    In order to perform high-speed three-dimensional (3D) shape measurements with structured light systems, high-speed projectors are required. One possibility is an array projector, which allows pattern projection at several tens of kilohertz by switching on and off the LEDs of various slide projectors. The different projection centers require a separate analysis, as the intensity received by the cameras depends on the projection direction and the object's bidirectional reflectance distribution function (BRDF). In this contribution, we investigate the BRDF-dependent errors of array-projection-based 3D sensors and propose an error compensation process.

  18. Measuring the effect of e-business on organizational performance in project based organizations

    Directory of Open Access Journals (Sweden)

    Soheil Sadi-Nezhad

    2017-12-01

    Full Text Available Recently, there have been significant development on e-business and nearly all business partners try to offer their products and services via internet. One primary question for the implementation of e-business is to measure the effect of this new facility on supply chain in project based organizations. Although e-business may not directly influence on organizational performance, it definitely influences on unifying customers and suppliers, which yields to a better performance of organizations. This study performs a study to measure the indirect effect of e-business on project based organizational performance. The proposed study of this paper designs a questionnaire and distributes it among 140 professional experts in different industries in province of Ontario, Canada. The survey examines different hypotheses for a possible correlation between e-business and integrated suppliers, e-business and customers, integrated customers and suppliers with organizational performance. The results of this survey indicate a positive relationship between all these components either directly or indirectly.

  19. The effect of project-based learning on students' statistical literacy levels for data representation

    Science.gov (United States)

    Koparan, Timur; Güven, Bülent

    2015-07-01

    The point of this study is to define the effect of project-based learning approach on 8th Grade secondary-school students' statistical literacy levels for data representation. To achieve this goal, a test which consists of 12 open-ended questions in accordance with the views of experts was developed. Seventy 8th grade secondary-school students, 35 in the experimental group and 35 in the control group, took this test twice, one before the application and one after the application. All the raw scores were turned into linear points by using the Winsteps 3.72 modelling program that makes the Rasch analysis and t-tests, and an ANCOVA analysis was carried out with the linear points. Depending on the findings, it was concluded that the project-based learning approach increases students' level of statistical literacy for data representation. Students' levels of statistical literacy before and after the application were shown through the obtained person-item maps.

  20. Project-Based Market Competition and Policy Implications for Sustainable Developments in Building and Construction Sectors

    Directory of Open Access Journals (Sweden)

    Min-Ren Yan

    2015-11-01

    Full Text Available Building and construction sectors are significant contributors to the global economy, but their energy consumption necessitates greater commitment to sustainable developments. There is therefore a growing demand for green innovation in the form of cleaner production and policies to meet the modern requirements of sustainability. However, the nature in which public work is undertaken is in an environment of project-based market competition, whereby contractors routinely bid for contracts under specific project awarding systems, and variations are accompanied with the unique scope of individual projects before the final goods or services are delivered. A comprehensive understanding of the characteristics and contractors’ behavior in systems could help to identify the leverage points of policies. This paper proposes a system dynamics model, with quantitative analysis and simulations, to demonstrate the problems of a system with different project awarding systems and ineffective market performance. The framework of market efficiency and performance measures has been proposed to evaluate the project-based competition mechanism. Managerial policy implications for market efficiency and sustainable developments can thus be systematically discussed and compared through iterative computer simulations and scenario analysis.

  1. Entrepreneurship skills development through project-based activity in Bachelor of Pharmacy program.

    Science.gov (United States)

    Shahiwala, Aliasgar

    2017-07-01

    To provide pharmacy students with an opportunity to develop entrepreneurial thinking and skills. A business proposal building project-based activity was integrated into a two-credit hour pharmacy management course during the eighth semester of the bachelor of pharmacy degree program. The student groups submitted their proposals, mimicking the process of submitting business proposals and obtaining approval in the real world. Essential management tasks including operation procedures, location and layout design, inventory management, personnel management, marketing management, and finance management were taught step-by-step so that students could work on a similar scenario with their proposal building. Students' career preferences were also measured at the beginning and end of the course. Course was assessed by written exffigam and rubric based project evaluation. Student feedbacks of the project were collected using a five-point Likert scale. The project-based activity was well integrated in the course. The project helped the students (n=72) to understand management concepts more clearly, which was reflected by their significantly higher (pproject was successfully designed and executed in a pharmacy management course within a bachelor of pharmacy curriculum. Based on the response received in this project, efforts will be made to provide guidance and support to the students by calling field experts such as pharmacy owners and financiers. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Learning With E-books and Project-based Strategy in a Community Health Nursing Course.

    Science.gov (United States)

    Sung, Tien-Wen; Wu, Ting-Ting

    2018-03-01

    With advances in information technology, "information-assisted instruction" has been gradually introduced to nursing education curricula. Specifically, the integration of an e-book system can effectively enhance nursing students' attention and interest. Most studies on nursing education that incorporated e-books have focused on the advantages of convenience and assistance provided by e-books. Few studies have addressed community health nursing and off-campus practice activities in relation to suitable teaching strategies for learning activities. This study involved designing and planning a multimedia e-book learning system with a project-based learning activity that conforms to the curriculum and practical requirements of a community health nursing course. The purpose was to reduce the gap between theory and practice and realize an effective learning process. For learning evaluations, a final examination analysis with an independent sample t test; a scoring scheme with intrateam, interteam, and expert ratings; and Bloom's taxonomy-based analysis were conducted. The evaluation results indicated that the comprehension and learning abilities of the experimental group using the e-book system with a mobile device were effectively improved. In addition, the exploratory process involved in project-based learning can develop multiple cognitive skills and problem-solving ability, thereby realizing effective learning.

  3. Project-based learning methodology in the area of microbiology applied to undergraduate medical research.

    Science.gov (United States)

    Mateo, Estibaliz; Sevillano, Elena

    2018-07-01

    In the recent years, there has been a decrease in the number of medical professionals dedicated to a research career. There is evidence that students with a research experience during their training acquire knowledge and skills that increase the probability of getting involved in research more successfully. In the Degree of Medicine (University of the Basque Country) the annual core subject 'Research Project' introduces students to research. The aim of this work was to implement a project-based learning methodology, with the students working on microbiology, and to analyse its result along time. Given an initial scenario, the students had to come up with a research idea related to medical microbiology and to carry out a research project, including writing a funding proposal, developing the experimental assays and analyzing and presenting their results to a congress organized by the University. Summative assessment was performed by both students and teachers. A satisfaction survey was carried out to gather the students' opinion. The overall results regarding to the classroom dynamics, learning results and motivation after the implementation were favourable. Students referred a greater interest about research than they had before. They would choose the project based methodology versus the traditional one.

  4. Perbandingan antara Keefektifan Model Guided Discovery Learning dan Project-Based Learning pada Matakuliah Geometri

    Directory of Open Access Journals (Sweden)

    Okky Riswandha Imawan

    2015-12-01

    Abstract This research aims to describe the effectiveness and effectiveness differences of the Guided Discovery Learning (GDL Model and the Project Based Learning (PjBL Model in terms of achievement, self-confidence, and critical thinking skills of students on the Solid Geometry subjects. This research was quasi experimental. The research subjects were two undergraduate classes of Mathematics Education Program, Ahmad Dahlan University, in their second semester, established at random. The data analysis to test the effectiveness of the GDL and PjBL Models in terms of each of the dependent variables used the t-test. The data analysis to test differences between effectiveness of the GDL and that of the PjBL Model used the MANOVA test. The results of this research show that viewed from achievement, self confidence, and critical thinking skills of the students are the application of the GDL Model on Solid Geometry subject is effective, the application of the PjBL Model on Solid Geometry subject is effective, and there is no difference in the effectiveness of GDL and PjBL Models on Solid Geometry subject in terms of achievement, self confidence, and critical thinking skills of the students. Keywords: guided discovery learning model, project-based learning model, achievement, self-confidence, critical thinking skills

  5. The Use of ICT Platforms to Promote Knowledge Exchange in Project-Based Organisations

    Directory of Open Access Journals (Sweden)

    Priyono Anjar

    2016-12-01

    Full Text Available This study aims to investigate the use of information and communication technology (ICT to support knowledge exchange in project-based organisations. The primary ICT tool investigated in this research is WhatsApp, a messaging application that has been widely used since its introduction. An ethnographic case study method was utilised to analyse qualitative data collected from interviews and focus group discussions. Three projects in an Indonesian university with a duration ranging from 8 months to 2 years were examined as object of investigations. Broadly, the findings show that ICT tools are generally useful in supporting knowledge exchange, which ultimately positively affects project performance. The project teams relied on WhatsApp for the success of the projects. Although face-to-face meetings were rare, team communication was highly intensive, supported by WhatsApp. In addition, managers are encouraged to promote knowledge exchange between team members. Through knowledge exchange, there will be knowledge development, which facilitates the invention of new techniques and methods for promoting project success. The most prominent findings are presented using direct quotations to provide first hand insight from the field. At the end of the paper, recommendations regarding what project managers should do during and after the project has been completed are presented. The recommendations are classified based on the knowledge management life cycle, representing a structured method to manage knowledge in project-based organisations.

  6. Improved performance of CdS/CdSe quantum dot-sensitized solar cells using Mn-doped PbS quantum dots as a catalyst in the counter electrode

    International Nuclear Information System (INIS)

    Kim, Byung-Man; Son, Min-Kyu; Kim, Soo-Kyoung; Hong, Na-Yeong; Park, Songyi; Jeong, Myeong-Soo; Seo, Hyunwoong; Prabakar, Kandasamy; Kim, Hee-Je

    2014-01-01

    Highlights: • PbS QDs synthesized using the SILAR method act not only as the electrochemical catalysts but as donors providing additional electrons under illumination. • The electrochemical and optical properties of the PbS QDs were enhanced considerably after Mn 2+ doping. • The electron supply from the counter electrode was significantly activated by Mn 2+ doping, improving the performance of QDSSC. - Abstract: This study reports the enhanced catalytic ability of Mn-doped PbS QDs synthesized using a successive ionic layer adsorption and reaction (SILAR) method for quantum dot-sensitized solar cells (QDSSCs). Electrochemical and optical analysis of each material showed that the catalytic ability of the PbS electrode was improved significantly by Mn 2+ doping. Two factors can explain this behavior. The first is that intentional impurities have an impact on the structure of the host material, such as increases in surface roughness. The other is that dopants create new energy states that delay the exciton recombination time and allow charge separation to be activated. As a result, the photoelectron supply from the counter electrode is accelerated, resulting in vigorous redox reactions at the polysulfide electrolyte. The performance of the CdS/CdSe QDSSC using a Mn-doped PbS counter electrode was compared with those using the Pt and PbS counter electrodes. Finally, a power conversion efficiency of 3.61% was achieved with the Mn-doped PbS counter electrode (V OC = 0.61 V, J SC = 11.67 mA cm −2 , FF = 0.51) under one sun illumination (100 mW cm −2 ), which is ∼40% higher than that of CdS/CdSe QDSSCs with the bare PbS counter electrode

  7. Project-based production and project management : Findings and trends in research on temporary systems in multiple contexts

    NARCIS (Netherlands)

    Pretorius, M.W.; Oerlemans, L.A.G.

    2014-01-01

    Globalisation is challenging almost every aspect of the political, economic, social and technological environment. Organisations, whether public or private, have to adapt their strategies and operations to stay competitive and efficient. Historically, organisations adopted project-based operations

  8. Country-Level Population and Downscaled Projections Based on the SRES B2 Scenario, 1990-2100

    Data.gov (United States)

    National Aeronautics and Space Administration — The Country-Level Population and Downscaled Projections Based on Special Report on Emissions Scenarios (SRES) B2 Scenario, 1990-2100, were based on the UN 1998...

  9. The Project Based Mechanisms of the Kyoto Protocol. Credible Instruments or Challenges to the Integrity of the Kyoto Protocol?

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi Waldegren, Linn

    2006-03-15

    The project based mechanisms of the Kyoto Protocol are innovative instruments which allow projects to earn credits for reducing greenhouse gas (GHG) emissions. The credits can in turn be used by countries to reach their emissions targets according to the Kyoto Protocol. The Project based mechanisms are known as the Clean Development Mechanism (CDM) and the Joint Implementation (JI). If the project based mechanisms are to be effective policy instruments they must ensure the integrity of the Kyoto Protocol, and their ability to promote and prove real emission reductions is critical. The environmental credibility of the project based mechanisms will also ensure their ability to promote cost effectiveness. Key concepts in this context are environmental and project additionality, and their role and value for the project based mechanisms are analyzed. Environmental additionality is established by comparing a project's emissions to a baseline. The baseline's credibility is thus vital. The concept of project additionality is somewhat controversial, but is nonetheless of equal importance. The case studies of CDM approved methodologies (AMs) and proposed projects suggest that there are credibility issues that need to be addressed if the project based mechanisms are to promote real emissions reductions.

  10. Enhanced photoelectrochemical performance of PbS sensitized Sb–SnO{sub 2}/TiO{sub 2} nanotube arrays electrode under visible light illumination

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jia; Tang, Chengli [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Xu, Hao, E-mail: xuhao@mail.xjtu.edu.cn [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Yan, Wei, E-mail: yanwei@mail.xjtu.edu.cn [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China)

    2015-06-05

    Highlights: • Sb–SnO{sub 2} is used to modify TiO{sub 2} NTAs by microwave method. • PbS is employed to sensitive Sb–SnO{sub 2}/TiO{sub 2} NTAs by S-SILAR method. • Sb–SnO{sub 2} improves electrons transfer and PbS enhances visible light absorption. • The composite electrode shows enhanced photoelectrochemical properties. • The composite electrode exhibits high hydrogen evolution and high QE. - Abstract: The novel PbS sensitized Sb–SnO{sub 2}/TiO{sub 2} nanotube arrays (NTAs) composite electrode (PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs) was fabricated by microwave combined with sonication-assisted successive ionic layer adsorption and reaction technique (S-SILAR). The obtained electrodes were characterized by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–Vis diffuse reflectance absorption spectra techniques. Enhanced photocurrent (15.52 mA/cm{sup 2}) of the PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs electrode was observed and can be attributed to the facile photo-generated electrons transfer and enhanced charge separation efficiency. Furthermore, the PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs composite electrode shows a higher H{sub 2} production rate than the Sb–SnO{sub 2}/TiO{sub 2} NTAs electrode and PbS/TiO{sub 2} NTAs electrode. The results indicate that the PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs electrode is a promising photoanode in visible photocatalytic water splitting.

  11. Ultra high pressure homogenization (UHPH inactivation of Bacillus amyloliquefaciens spores in phosphate buffered saline (PBS and milk

    Directory of Open Access Journals (Sweden)

    Peng eDong

    2015-07-01

    Full Text Available Ultra high pressure homogenization (UHPH opens up new areas for dynamic high pressure assisted thermal sterilization of liquids. Bacillus amyloliquefaciens spores are resistant to high isostatic pressure and temperature and were suggested as potential surrogate for high pressure thermal sterilization validation. B. amyloliquefaciens spores suspended in PBS buffer (0.01 M, pH 7.0, low fat milk (1.5%, pH 6.7 and whole milk (3.5%, pH 6.7 at initial concentration of ~106 CFU/mL were subjected to UHPH treatments at 200, 300 and 350 MPa with an inlet temperature at ~80 °C. Thermal inactivation kinetics of B. amyloliquefaciens spores in PBS and milk were assessed with thin wall glass capillaries and modeled using mechanistic linear first order and Weibull models. The residence time during UHPH treatments was estimated to determine the contribution of temperature to spore inactivation by UHPH. No sublethal injury was detected after UHPH treatments using sodium chloride as selective component in the nutrient agar medium. The inactivation profiles of spores in PBS buffer and milk were compared and fat provided no clear protective effect for spores against treatments. Treatment at 200 MPa with valve temperatures lower than 125 °C caused no reduction of spores. A reduction of 3.5 log10 CFU/mL of B. amyloliquefaciens spores was achieved by treatment at 350 MPa with a valve temperature higher than 150 °C. The modeled thermal inactivation and observed inactivation during UHPH treatments suggest that temperature could be the main lethal effect driving inactivation.

  12. Assessing the quality of proton PBS treatment delivery using machine log files: comprehensive analysis of clinical treatments delivered at PSI Gantry 2

    International Nuclear Information System (INIS)

    Scandurra, D; Albertini, F; Van der Meer, R; Meier, G; Weber, D C; Bolsi, A; Lomax, A

    2016-01-01

    Pencil beam scanning (PBS) proton therapy requires the delivery of many thousand proton beams, each modulated for position, energy and monitor units, to provide a highly conformal patient treatment. The quality of the treatment is dependent on the delivery accuracy of each beam and at each fraction. In this work we describe the use of treatment log files, which are a record of the machine parameters for a given field delivery on a given fraction, to investigate the integrity of treatment delivery compared to the nominal planned dose. The dosimetry-relevant log file parameters are used to reconstruct the 3D dose distribution on the patient anatomy, using a TPS-independent dose calculation system. The analysis was performed for patients treated at Paul Scherrer Institute on Gantry 2, both for individual fields and per series (or plan), and delivery quality was assessed by determining the percentage of voxels in the log file dose distribution within  +/−  1% of the nominal dose. It was seen that, for all series delivered, the mean pass rate is 96.4%. Furthermore, this work establishes a correlation between the delivery quality of a field and the beam position accuracy. This correlation is evident for all delivered fields regardless of individual patient or plan characteristics. We have also detailed further usefulness of log file analysis within our clinical workflow. In summary, we have highlighted that the integrity of PBS treatment delivery is dependent on daily machine performance and is specifically highly correlated with the accuracy of beam position. We believe this information will be useful for driving machine performance improvements in the PBS field. (paper)

  13. Developing Project Based Learning E-Module for the Course of Video Editing

    Directory of Open Access Journals (Sweden)

    Ketut Krisnayuni

    2017-04-01

    Full Text Available This study examined the development of an electronic module for the course of video editing and analyzed the students’ response of the e-module. A waterfall model was adopted in the development process of the e-module that consisted of five stages namely (1 analysis; (2 design; (3 implementation; (4 evaluation; and (5 maintenance. The subjects of this study were the students of class XI at SMK Negeri 1 Sukasada. Project Based Learning was used as the basis of the e-module development as the most relevant learning model to meet the students’needs and the schools’ situation. The data of the students’ response about the e-module were collected through a questionnaire. The students’ response was very positive indicated by the mean score of 94,37. It was concluded that the developed e-modul was categorized as very good.

  14. Something of value Governance of Projects in the Project-Based Organisation

    DEFF Research Database (Denmark)

    Riis, Eva

    2013-01-01

    The paper presents a conceptual framework for studying Governance of Projects and issues of value in the project-based organisation. Attempts at exploring and conceptualising the issues in the current literature are reviewed. Issues pertinent to gaining value by Governance of Projects have mainly...... for a better understanding of Governance of Projects and value contribution. The findings presented here form the conceptual foundation for subsequent empirical studies of value by Governance of Projects....... been explored from the perspective of economic theory. Models found in the literature are not typically concerned with value for the implementing organisation as a whole; their scope is limited to the time just after project completion. No valid, empirically-based models of value creation by Governance...

  15. Students' and teachers' perceptions: initial achievements of a Project-Based Engineering School

    Science.gov (United States)

    Terrón-López, María-José; Velasco-Quintana, Paloma-Julia; García-García, María-José; Ocampo, Jared R.

    2017-11-01

    A unified academic model based on the project-based learning (PBL) methodology was implemented, in the 2012-2013 period, in the School of Engineering at Universidad Europea de Madrid. The purpose of this paper is to explore whether teachers and students participating in the capstone projects feel that the objectives for which this methodology was designed for are being achieved. The data were collected through interviews to participants at the end of the PBL experience. The results are encouraging, as students seem to be more motivated, and they say that they are experiencing deeper learning, and have developed key competitive skills required for their professional lives. Findings also suggest that teachers face positively the PBL as a learning approach since they perceive that students obtain a deeper learning, develop transversal skills with the projects and are more engaged with their studies. Implications and recommendations for the future of the model are also discussed.

  16. Evaluating visual discomfort in stereoscopic projection-based CAVE system with a close viewing distance

    Science.gov (United States)

    Song, Weitao; Weng, Dongdong; Feng, Dan; Li, Yuqian; Liu, Yue; Wang, Yongtian

    2015-05-01

    As one of popular immersive Virtual Reality (VR) systems, stereoscopic cave automatic virtual environment (CAVE) system is typically consisted of 4 to 6 3m-by-3m sides of a room made of rear-projected screens. While many endeavors have been made to reduce the size of the projection-based CAVE system, the issue of asthenopia caused by lengthy exposure to stereoscopic images in such CAVE with a close viewing distance was seldom tangled. In this paper, we propose a light-weighted approach which utilizes a convex eyepiece to reduce visual discomfort induced by stereoscopic vision. An empirical experiment was conducted to examine the feasibility of convex eyepiece in a large depth of field (DOF) at close viewing distance both objectively and subjectively. The result shows the positive effects of convex eyepiece on the relief of eyestrain.

  17. Promoting Information Literacy of Pre-Medical Students through Project-Based Learning: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Reya Saliba

    2017-10-01

    Full Text Available This study describes the implementation of information literacy (IL skills through the use of the project-based learning (PjBL method in an English for Academic Purposes (EAP course. Participants were Arabic speaking students enrolled in the Foundation Program that prepares them for the premedical curriculum in a U.S. medical   college in the State of Qatar. A mixed methods approach consisting of a survey, three focus groups, and instructors' observations was used to gather the needed data. The results showed a significant increase in students' advanced research skills. This study emphasizes the benefit of using the PjBL method to develop students' IL skills. It also reinforces the vital role of faculty-librarian partnership in designing learning activities that engage students, foster their critical thinking, and develop their metacognitive skills.

  18. Penerapan Model Project Based Learning untuk Meningkatan Kinerja dan Prestasi Belajar Fisika Siswa SMK

    Directory of Open Access Journals (Sweden)

    Eko Mulyadi

    2016-01-01

    Full Text Available This study aims at improving the students’ performance and achievement in grade XI AV1 of SMK Negeri 3 Yogyakarta with the application of Project Based Learning in Physics learning for Static Electricity and Direct Current Electricity competencies. This study used a classroom action research approach implementing two cycles. Every cycle consisted of planning, action, observation and reflection. The PjBL included the steps of determining, planning, scheduling, monitoring, presentation and evaluation. The aspects of the achievement were measured by a pre-test, a product assessment, and a post-test. The results showed that the application of PjBL improved the performance up to 18.75% and improved the achievement 15.70 and 24.63 for the first cycle and the second cycle respectively.

  19. A project-based system for including farmers in the EU ETS

    DEFF Research Database (Denmark)

    Brandt, Urs Steiner; Svendsen, Gert Tinggaard

    2011-01-01

    as ‘the missing link’ in past climate negotiations. We argue that farmers have relatively low marginal reduction costs and that consequences in terms of the effect on permit price and technology are overall positive in the EU Emission Trading System (ETS). Thus, we propose a project-based system......Farmers in the EU do not trade greenhouse gases under the Kyoto agreement. This is an empirical puzzle because agriculture is a significant contributor of greenhouse gases (GHG) in the EU and may harvest private net gains from trade. Furthermore, the US has strongly advocated land-use practices...... for including the farming practices in the EU ETS that reduces the uncertainty from measuring emission reduction in this sector. The system encourages GHG reduction either by introducing a new and less polluting practice or by reducing the polluting activity. When doing so, farmers will receive GHG permits...

  20. A project based learning experience through best use of state-of-the-art technology

    Directory of Open Access Journals (Sweden)

    Juan José López Berrio

    2016-01-01

    Full Text Available Our proposal consists in activating the most important talent in the education institutions (their students, converting them in the change movement they need. How do we do that? We attract them through an enriching and disruptive programme, that suggest them a real entrepreneurship challenge, guiding and empowering them to reach the goals planned. Our vehicle is the Innovation Lab, a permanent program, where through a project based learning and working as a real and modern startup, the students work and collaborate using state of the art technology and methodologies, such as cloud computing, design thinking, flipped classroom, gamification, etc., by combining on-line work and sessions at school. The idea is revolutionary and innovative but also perfectly aligned with the content of the Horizon 2020-Schools Edition. We have achieved great results, both qualitative and quantitative, as you would be able to see along the article.

  1. Project-based learning in the teaching-learning process university. A longitudinal study

    Directory of Open Access Journals (Sweden)

    Sandoval Hamón Leyla Angélica

    2017-01-01

    Full Text Available The European Higher Education Area promotes the change in teaching-learning, where students have a more active role in their educational process. The main objective of this work is to analyse the use of an alternative proposal, focus in student-based teamwork activities, who seek to favour the acquisition and deepening of knowledge and skills. The implementation of this research was carried out by means of a longitudinal study in the subject of the degree of Economics, with the development of the methodology of Project Based Learning integrating the ICTs and improving the evaluation process (e.g. establishing headings and psychometric analysis of knowledge tests. The results of the research showed an improvement in the learning process from the observation, collection of works, analysis of knowledge tests and the official survey by students to assess the activity and the development of their competitors.

  2. A Project-based Learning curricular approach in a Production Engineering Program

    Directory of Open Access Journals (Sweden)

    Simone Borges Simão Monteiro

    2017-09-01

    Full Text Available Abstract The Industrial Engineering undergraduate program offered at the University of Brasília was structured on Project Based Learning (PBL methodology. This innovative educational proposal allows the students to deploy their technical competencies through real problem solving situations. The methodology also stimulates the development of the students’ soft skills, by exposing them to a challenging environment. At the end of each project, the results are presented to an external agent, and are subsequently implemented. The objective of this paper is to present the evolution of the PSP courses, which adopt as guidelines both the PMBOK project management framework, as well as content from specific technical courses related to the project’s subject. One other relevant aspect of the PSP courses is their involvement of both undergraduate and graduate students from different Engineering areas, such as Industrial, Mechanical and Civil Engineering, which serves to foster a more holistic and integrated problem-solving skillset.

  3. The Model of Lake Operation in Water Transfer Projects Based on the Theory of Water- right

    Science.gov (United States)

    Bi-peng, Yan; Chao, Liu; Fang-ping, Tang

    the lake operation is a very important content in Water Transfer Projects. The previous studies have not any related to water-right and water- price previous. In this paper, water right is divided into three parts, one is initialization waterright, another is by investment, and the third is government's water- right re-distribution. The water-right distribution model is also build. After analyzing the cost in water transfer project, a model and computation method for the capacity price as well as quantity price is proposed. The model of lake operation in water transfer projects base on the theory of water- right is also build. The simulation regulation for the lake was carried out by using historical data and Genetic Algorithms. Water supply and impoundment control line of the lake was proposed. The result can be used by south to north water transfer projects.

  4. Local Projection-Based Stabilized Mixed Finite Element Methods for Kirchhoff Plate Bending Problems

    Directory of Open Access Journals (Sweden)

    Xuehai Huang

    2013-01-01

    Full Text Available Based on stress-deflection variational formulation, we propose a family of local projection-based stabilized mixed finite element methods for Kirchhoff plate bending problems. According to the error equations, we obtain the error estimates of the approximation to stress tensor in energy norm. And by duality argument, error estimates of the approximation to deflection in H1-norm are achieved. Then we design an a posteriori error estimator which is closely related to the equilibrium equation, constitutive equation, and nonconformity of the finite element spaces. With the help of Zienkiewicz-Guzmán-Neilan element spaces, we prove the reliability of the a posteriori error estimator. And the efficiency of the a posteriori error estimator is proved by standard bubble function argument.

  5. A Project-Based Language Learning Model for Improving the Willingness to Communicate of EFL Students

    Directory of Open Access Journals (Sweden)

    Ibrahim Farouck

    2016-04-01

    Full Text Available Anxiety and inadequate motivation due to misapplication of some language teaching methodologies and learning materials have been shown to affect the Willingness to Communicate of students in EFL programs. This study used a Project-Based Language Learning to improve learning motivation and content relevance. Students were grouped into pairs to conduct fieldwork activities on their chosen topics and learned the English language that was suitable for describing their activities and outcomes. They interacted with content and peers through Web 2.0 environments. In the classroom, they engaged in communicative tasks in a jigsaw format and presented their projects where their peers used an online rubric and forum to give feedback. They also participated in a speech contest with peers outside their class or from another university in order to broaden their confidence. Findings from this study show that students were able to develop the language and evaluation skills for presentation. Additionally, they indicated a reduction in communication anxiety.

  6. Changing the Curriculum to Problem-Based and Project-Based Learning

    DEFF Research Database (Denmark)

    Kolmos, Anette

    2012-01-01

    Problem based and project based learning (PBL) models are implemented all over the world in various versions at curriculum or course level. Due to this development, the conceptual understanding of PBL has become more diverse and sometimes confusing. This chapter summarizes the conceptual work done...... by the UNESCO Chair in PBL in engineering education in order to define PBL as a set of core learning principles that can be applied in practice. The PBL learning principles are formulated within three aspects: learning, social, and content of study. Furthermore, the chapter contains a PBL curriculum model......, which can be used for analysis and development of the curriculum or single courses. Seven elements are identified as important for the planning and implementation of PBL learning principles, and for each of the elements there are several choices to be made. Finally, the chapter presents concrete advice...

  7. Projection-based circular constrained state estimation and fusion over long-haul links

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qiang [ORNL; Rao, Nageswara S. [ORNL

    2017-07-01

    In this paper, we consider a scenario where sensors are deployed over a large geographical area for tracking a target with circular nonlinear constraints on its motion dynamics. The sensor state estimates are sent over long-haul networks to a remote fusion center for fusion. We are interested in different ways to incorporate the constraints into the estimation and fusion process in the presence of communication loss. In particular, we consider closed-form projection-based solutions, including rules for fusing the estimates and for incorporating the constraints, which jointly can guarantee timely fusion often required in realtime systems. We test the performance of these methods in the long-haul tracking environment using a simple example.

  8. Social network analysis of a project-based introductory physics course

    Science.gov (United States)

    Oakley, Christopher

    2016-03-01

    Research suggests that students benefit from peer interaction and active engagement in the classroom. The quality, nature, effect of these interactions is currently being explored by Physics Education Researchers. Spelman College offers an introductory physics sequence that addresses content and research skills by engaging students in open-ended research projects, a form of Project-Based Learning. Students have been surveyed at regular intervals during the second semester of trigonometry-based course to determine the frequency of interactions in and out of class. These interactions can be with current or past students, tutors, and instructors. This line of inquiry focuses on metrics of Social Network analysis, such as centrality of participants as well as segmentation of groups. Further research will refine and highlight deeper questions regarding student performance in this pedagogy and course sequence.

  9. Successful Project Based Learning (PBL) Across Disciplines Geared Towards Middle School: An Example from a Wetlands PBL Unit in Reno, Nevada, USA

    Science.gov (United States)

    Howard, K. L.; Suchy-Mabrouk, A.; Noble, P. J.; Mensing, S. A.; Ewing-Taylor, J.

    2014-12-01

    A growing need for broad dissemination of current scientific research and improved scientific literacy requires new models of professional development that allow for direct collaboration between educators and university researchers. One example is a project funded by the National Science Foundation (NSF) as part of a study titled, "Reconstructing 2500 years of environmental change at the periphery of Rome: Integrating paleoecology and socioeconomic history to understand human response to climate." This project involves a team of middle school teachers working with researchers at the University of Nevada, Reno (UNR) to gain first-hand knowledge in multidisciplinary research connecting science and society, and applies a similar approach in the classroom. In 2013, the team's science teacher traveled to Italy as a member of the science research group. A series of workshops introduced the remaining teachers to the research project. Teachers collaborated to develop a Project Based Learning (PBL) unit that incorporated Next Generation Science Standards and encompassed English, Social Studies, Math, and Science curricula using a pedagogical approach different from the single subject-based PBL's usually taught in their school district. The PBL unit draws on the NSF study and focuses on exploring the balance between economic and environmental issues surrounding local wetlands. In May 2014, 160 middle school students worked in groups to create and test a question about physio-chemical parameters in a nearby wetland and used these data to discuss local economic development. Initially, students claimed polarized views of environmental issues or economic development interests; however, during a multimedia session showcasing results, students communicated more informed perspectives that clearly incorporated knowledge gained from their own research. Some students were able to make recommendations for good practices involving planned economic development near the wetland

  10. Water-mediated green synthesis of PbS quantum dot and its glutathione and biotin conjugates for non-invasive live cell imaging

    Science.gov (United States)

    Vijaya Bharathi, M.; Maiti, Santanu; Sarkar, Bidisha; Ghosh, Kaustab; Paira, Priyankar

    2018-03-01

    This study addresses the cellular uptake of nanomaterials in the field of bio-applications. In the present study, we have synthesized water-soluble lead sulfide quantum dot (PbS QD) with glutathione and 3-MPA (mercaptopropionic acid) as the stabilizing ligand using a green approach. 3-MPA-capped QDs were further modified with streptavidin and then bound to biotin because of its high conjugation efficiency. Labelling and bio-imaging of cells with these bio-conjugated QDs were evaluated. The bright red fluorescence from these types of QDs in HeLa cells makes these materials suitable for deep tissue imaging.

  11. Improving 4D plan quality for PBS-based liver tumour treatments by combining online image guided beam gating with rescanning

    Science.gov (United States)

    Zhang, Ye; Knopf, Antje-Christin; Weber, Damien Charles; Lomax, Antony John

    2015-10-01

    Pencil beam scanned (PBS) proton therapy has many advantages over conventional radiotherapy, but its effectiveness for treating mobile tumours remains questionable. Gating dose delivery to the breathing pattern is a well-developed method in conventional radiotherapy for mitigating tumour-motion, but its clinical efficiency for PBS proton therapy is not yet well documented. In this study, the dosimetric benefits and the treatment efficiency of beam gating for PBS proton therapy has been comprehensively evaluated. A series of dedicated 4D dose calculations (4DDC) have been performed on 9 different 4DCT(MRI) liver data sets, which give realistic 4DCT extracting motion information from 4DMRI. The value of 4DCT(MRI) is its capability of providing not only patient geometries and deformable breathing characteristics, but also includes variations in the breathing patterns between breathing cycles. In order to monitor target motion and derive a gating signal, we simulate time-resolved beams’ eye view (BEV) x-ray images as an online motion surrogate. 4DDCs have been performed using three amplitude-based gating window sizes (10/5/3 mm) with motion surrogates derived from either pre-implanted fiducial markers or the diaphragm. In addition, gating has also been simulated in combination with up to 19 times rescanning using either volumetric or layered approaches. The quality of the resulting 4DDC plans has been quantified in terms of the plan homogeneity index (HI), total treatment time and duty cycle. Results show that neither beam gating nor rescanning alone can fully retrieve the plan homogeneity of the static reference plan. Especially for variable breathing patterns, reductions of the effective duty cycle to as low as 10% have been observed with the smallest gating rescanning window (3 mm), implying that gating on its own for such cases would result in much longer treatment times. In addition, when rescanning is applied on its own, large differences between volumetric

  12. TU-H-BRC-03: Evaluation of Very High-Energy Electron (VHEE) Beams in Comparison to VMAT and PBS Treatment Plans

    Energy Technology Data Exchange (ETDEWEB)

    Schueler, E; Loo, B; Maxim, P [Stanford University School of Medicine, Palo Alto, California (United States); Eriksson, K; Hynning, E [RaySearch Laboratories, Stockholm (Sweden)

    2016-06-15

    Purpose: The aim of this study was to evaluate the performance of very high-energy electron (VHEE) beams in comparison to clinically delivered treatment plans generated with volumetric modulated arc therapy (VMAT) and proton pencil beam scanning (PBS) technology. Methods: Three clinical cases were selected (prostate, lung, and pediatric CNS). The VHEE plans were calculated in the Monte Carlo EGSnrc code and pencil beam doses were calculated using the DOSxyznrc MC code for 100 and 200 MeV beams. Treatment plans with VHEE, VMAT, and PBS were optimized in a research version of RayStation using an in house build script in order to minimize operator bias between the different techniques. Results: For the prostate cancer case, the PBS plan showed lower mean organ at risk (OAR) doses compared to the other modalities. An exception was the femoral heads, due to the lateral beam arrangements. The VMAT plan showed lower mean doses to the rectum and the bladder compared to the 100 MeV VHEE plan. The lung cancer case showed minor differences between the three modalities. However, the PBS plan showed a lower contralateral lung dose. The pediatric CNS case showed a better conformity and lower spinal cord dose for the 100 MeV VHEE plan. For all cases, the 200 MeV VHEE plans were found to be similar to or better than the 100 MeV VHEE plans. Conclusion: The present study showed that VHEE plans are similar or superior to VMAT plans with reduced mean OAR dose and increased target conformity for a variety of clinical cases. With increased VHEE energy, better conformity and even higher reductions in mean OAR doses can be achieved. Funding: DoD, Award#:W81XWH-13-1-0165, Weston Havens Foundation, Bio-X (Stanford University), the Office of the Dean of the Medical School, the Office of the Provost (Stanford University), and the Swedish Childhood Cancer Foundation. BL and PM are founders of TibaRay,Inc. BL and PM have received research grants from Varian and RaySearch Laboratory.

  13. Combination of short-length TiO_2 nanorod arrays and compact PbS quantum-dot thin films for efficient solid-state quantum-dot-sensitized solar cells

    International Nuclear Information System (INIS)

    Zhang, Zhengguo; Shi, Chengwu; Chen, Junjun; Xiao, Guannan; Li, Long

    2017-01-01

    Graphical abstract: The TiO_2 nanorod array with the length of 600 nm, the diameter of 20 nm, the areal density of 500 μm"−"2 was successfully prepared. The compact PbS quantum-dot thin film was firstly obtained on the TiO_2 nanorod array by spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol. The photoelectric conversion efficiency (PCE) of the compact PbS quantum-dot thin film sensitized solar cells achieved 4.10% using spiro-OMeTAD as a hole transporting layer, while the PCE of the PbS quantum-dot sensitized solar cells was only 0.54%. - Highlights: • Preparation of TiO_2 nanorod arrays with the length of 600 nm, diameter of 20 nm. • The compact PbS QD thin film and short-length TiO_2 nanorod array were combined. • EDT addition improved PbS nanoparticle coverage and photovoltaic performance. • The compact PbS QD thin film sensitized solar cell achieved the PCE of 4.10%. - Abstract: Considering the balance of the hole diffusion length and the loading quantity of quantum-dots, the rutile TiO_2 nanorod array with the length of 600 nm, the diameter of 20 nm, and the areal density of 500 μm"−"2 is successfully prepared by the hydrothermal method using the aqueous grown solution of 38 mM titanium isopropoxide and 6 M hydrochloric acid at 170 °C for 105 min. The compact PbS quantum-dot thin film on the TiO_2 nanorod array is firstly obtained by the spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol (EDT). The result reveals that the strong interaction between lead and EDT is very important to control the crystallite size of PbS quantum-dots and obtain the compact PbS quantum-dot thin film on the TiO_2 nanorod array. The all solid-state sensitized solar cell with the combination of the short-length, high-density TiO_2 nanorod array and the compact PbS quantum-dot thin film achieves the photoelectric conversion efficiency of 4.10%, along with an open

  14. Combination of short-length TiO{sub 2} nanorod arrays and compact PbS quantum-dot thin films for efficient solid-state quantum-dot-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhengguo [School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009 (China); School of Chemistry and Chemical Engineering, Beifang University of Nationalities, Yinchuan 750021 (China); Shi, Chengwu, E-mail: shicw506@foxmail.com [School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009 (China); Chen, Junjun; Xiao, Guannan; Li, Long [School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009 (China)

    2017-07-15

    Graphical abstract: The TiO{sub 2} nanorod array with the length of 600 nm, the diameter of 20 nm, the areal density of 500 μm{sup −2} was successfully prepared. The compact PbS quantum-dot thin film was firstly obtained on the TiO{sub 2} nanorod array by spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol. The photoelectric conversion efficiency (PCE) of the compact PbS quantum-dot thin film sensitized solar cells achieved 4.10% using spiro-OMeTAD as a hole transporting layer, while the PCE of the PbS quantum-dot sensitized solar cells was only 0.54%. - Highlights: • Preparation of TiO{sub 2} nanorod arrays with the length of 600 nm, diameter of 20 nm. • The compact PbS QD thin film and short-length TiO{sub 2} nanorod array were combined. • EDT addition improved PbS nanoparticle coverage and photovoltaic performance. • The compact PbS QD thin film sensitized solar cell achieved the PCE of 4.10%. - Abstract: Considering the balance of the hole diffusion length and the loading quantity of quantum-dots, the rutile TiO{sub 2} nanorod array with the length of 600 nm, the diameter of 20 nm, and the areal density of 500 μm{sup −2} is successfully prepared by the hydrothermal method using the aqueous grown solution of 38 mM titanium isopropoxide and 6 M hydrochloric acid at 170 °C for 105 min. The compact PbS quantum-dot thin film on the TiO{sub 2} nanorod array is firstly obtained by the spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol (EDT). The result reveals that the strong interaction between lead and EDT is very important to control the crystallite size of PbS quantum-dots and obtain the compact PbS quantum-dot thin film on the TiO{sub 2} nanorod array. The all solid-state sensitized solar cell with the combination of the short-length, high-density TiO{sub 2} nanorod array and the compact PbS quantum-dot thin film achieves the photoelectric conversion

  15. Evolution of project-based learning in small groups in environmental engineering courses

    Directory of Open Access Journals (Sweden)

    Jesús M. Requies

    2018-03-01

    Full Text Available This work presents the assessment of the development and evolution of an active methodology (Project-Based Learning –PBL- implemented on the course “Unit Operations in Environmental Engineering”, within the bachelor’s degree in Environmental Engineering, with the purpose of decreasing the dropout rate in this course. After the initial design and implementation of this methodology during the first academic year (12/13, different modifications were adopted in the following ones (13-14, 14-15 & 15-16 in order to optimize the student’s and professor’s work load as well as correct some malfunctions observed in the initial design of the PBL. This active methodology seeks to make students the main architects of their own learning processes. Accordingly, they have to identify their learning needs, which is a highly motivating approach both for their curricular development and for attaining the required learning outcomes in this field of knowledge. The results obtained show that working in small teams (cooperative work enhances each group member’s self–learning capabilities. Moreover, academic marks improve when compared to traditional learning methodologies. Nevertheless, the implementation of more active methodologies, such as project-based learning, in small groups has certain specific characteristics. In this case it has been implemented simultaneously in two different groups of 10 students each one. Such small groups are more heterogeneoussince the presence of two highly motivated students or not can vary or affect the whole group’s attitude and academic results.

  16. Project-based learning with international collaboration for training biomedical engineers.

    Science.gov (United States)

    Krishnan, Shankar

    2011-01-01

    Training biomedical engineers while effectively keeping up with the fast paced scientific breakthroughs and the growth in technical innovations poses arduous challenges for educators. Traditional pedagogical methods are employed for coping with the increasing demands in biomedical engineering (BME) training and continuous improvements have been attempted with some success. Project-based learning (PBL) is an academic effort that challenges students by making them carry out interdisciplinary projects aimed at accomplishing a wide range of student learning outcomes. PBL has been shown to be effective in the medical field and has been adopted by other fields including engineering. The impact of globalization in healthcare appears to be steadily increasing which necessitates the inclusion of awareness of relevant international activities in the curriculum. Numerous difficulties are encountered when the formation of a collaborative team is tried, and additional difficulties occur as the collaboration team is extended to international partners. Understanding and agreement of responsibilities becomes somewhat complex and hence the collaborative project has to be planned and executed with clear understanding by all partners and participants. A model for training BME students by adopting PBL with international collaboration is proposed. The results of previous BME project work with international collaboration fit partially into the model. There were many logistic issues and constraints; however, the collaborative projects themselves greatly enhanced the student learning outcomes. This PBL type of learning experience tends to promote long term retention of multidisciplinary material and foster high-order cognitive activities such as analysis, synthesis and evaluation. In addition to introducing the students to experiences encountered in the real-life workforce, the proposed approach enhances developing professional contracts and global networking. In conclusion, despite

  17. PENGEMBANGAN LKS BERBASIS PROJECT BASED LEARNING UNTUK PEMBELAJARAN MATERI SEGITIGA DI KELAS VII

    Directory of Open Access Journals (Sweden)

    Dian Novita

    2016-06-01

    Full Text Available Penelitian ini merupakan penelitian pengembangan yang bertujuan untuk (1mengetahui karakteristik LKS berbasis Project Based Learning (PjBL yang valid dan praktis dalam pembelajaran materi segitiga di kelas VII; (2mengetahui efek potensial penggunaan LKS berbasis PjBL terhadap hasil belajar siswa dalam pembelajaran materi segitiga di kelas VII. Metode penelitian pengembangan yang digunakan adalah model  ADDIE (Analysis, Design, Development, Implementation, and Evaluation. Teknik pengumpulan data yang digunakan adalah walkthrough, tes hasil belajar dan angket. Dari tes hasil belajar, diperoleh bahwa sebesar 82,5% siswa telah mencapai kategori tuntas dan 17,5% belum tuntas dengan KKM 75. Hasil angket respon siswa menunjukkan bahwa untuk pelaksanaan pembelajaran menggunakan LKS berbasis PjBL telah mencapai kriteria kepraktisan. Kemudian untuk LKS berbasis PjBL yang telah didesain, divalidasi oleh beberapa pakar, kemudian direvisi berdasarkan saran dari para pakar tersebut. LKS yang telah direvisi tersebut dianggap telah memenuhi kriteria kevalidan dan kepraktisan sehingga dapat digunakan dalam pembelajaran materi segitiga di kelas VII. Kesimpulan dari penelitian ini adalah (1 LKS bebasis PjBL yang dikembangkan valid, tergambar dari konten (sesuai dengan kurikulum untuk materi segitiga, konstruk (sesuai dengan prinsip PjBL, dan bahasa (sesuai dengan ejaan yang disempurnakan (EYD. Kepraktisan tergambar dari proses kerja siswa dalam melaksanakan LKS dan hasil angket respon siswa terhadap pembelajaran menggunakan LKS berbasis PjBL; (2 dari hasil latihan yang dikerjakan oleh siswa, LKS berbasis PjBL memiliki efek potensial terhadap hasil belajar, yakni sebanyak 33 siswa termasuk kategori tuntas (82,5% dan 7 orang belum tuntas (17,5%, dengan KKM 75. Kata Kunci : LKS, Project Based Learning DOI: http://dx.doi.org/10.22342/jpm.10.2.3626.1-12

  18. The influence of knowledge flow on sustainable innovation in a project-based industry : From demonstration to limited adoption of eco-innovations

    NARCIS (Netherlands)

    Bossink, Bart

    2018-01-01

    The effect of the flow of knowledge on sustainable innovation in project-based firms in project-based industries is the subject of in-depth research in this paper. It studies the simultaneous functioning and effects of knowledge flow mechanisms on sustainable innovation in project-based firms in

  19. 24 CFR 1000.103 - How may IHBG funds be used for tenant-based or project-based rental assistance?

    Science.gov (United States)

    2010-04-01

    ... Housing Activities § 1000.103 How may IHBG funds be used for tenant-based or project-based rental assistance? (a) IHBG funds may be used for project-based or tenant-based rental assistance. (b) IHBG funds may be used for project-based or tenant-based rental assistance that is provided in a manner...

  20. Introducing Project-Based Instruction in the Saudi ESP Classroom: A Study in Qassim University

    Science.gov (United States)

    Alsamani, Abdul-Aziz Saleh; Daif-Allah, Ayman Sabry

    2016-01-01

    The aim of this paper is to study the impact of introducing an integrative pedagogical approach in the ESP classes on developing the English language vocabulary of Computer Science and Information Technology students in the College of Science, Qassim University. The study suggests a framework for an ESP course-design employing students' project…