37 research outputs found
Supplemental data for "A random walker algorithm for plate boundary detection in spherical mantle convection models and global geophysical datasets: application to Euler vector determination"
No full textSupplemental dataset for the manuscript "A random walker algorithm for plate boundary detection in spherical mantle convection models and global geophysical datasets: application to Euler vector determination"
Temperature affects the silicate morphology in a diatom
No full textTemperature affects the silicate morphology in a diatom Javaheri, N.; Dries, R.M.; Burson, A.M.; Stal, L.J.; Sloot, P.M.A.; Kaandorp, J.A. Published in: Scientific Reports DOI: 10.1038/srep11652 Link to publication Citation for published version (APA): Javaheri, N., Dries, R., Burson, A., Stal, L. J., Sloot, P. M. A., & Kaandorp, J. A. (2015). Temperature affects the silicate morphology in a diatom. Scientific Reports, 5, [11652]. https://doi.org/10.1038/srep11652 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. , and 23 °C ). We observed three distinct temperature-dependent growth phases. The morphology of silica was investigated using scanning electron microscopy followed by image analysis and supervised learning. The silica in the valves of the same species showed different structures: a mesh-like pattern in silicon-rich cultures and a treelike pattern in silicon-limited cultures. Moreover, temperature affected this silica pattern, especially in silicon-limited cultures. We conclude that cells grown at 14 °C and 18 °C divide more successfully in Si-limited conditions by developing a tree-like pattern (lower silicification)
Prevalence and etiologies of macrosomia and low birth weight in 1000 neonates at Javaheri hospital in Tehran
No full textBackground and aimLow birth weight is one of the important problems in many societies especially developing ones. The survival rate of infants has a direct relationship with their birth weight. The aim of This cross-sectional study was to determine the prevalence and etiologies of Prevalence and etiologies of macrosomia and low birth weight in 1000 neonates of low birth weight (LBW) as well as macrosomia and their possible etiologies. Materials and methods1000 neonates were sequentially selected by nonrandom sampling method over 6 months in 2006 at Javaheri hospital in Tehran. By reviewing their medical records, the birth weight of the subjects and other variables of the study were assessed. Independent T and Qui-square tests were used for data analysis. FindingsIn this study cross sectional- study mean weigh of the neonates was 2957±910 gr. 7% of the subjects suffered from low birth weight (mean=2371±260) and 3% had macrosomia (mean=4247±240). A significant relationship was found between birth weight and gestational age of the neonates. 10% of mothers having neonates with macrosomia had gestational diabetes. The etiology of macrosomia was not known in most cases. The most common causes of low birth weight included premature rupture of membranes, twin gestation, fetal distress and maternal conditions. ConclusionAppropriate gestational care, risk factor detection before pregnancy and improvement of quantity as well as quality of maternal child health services can reduce the number of low- birth-weight infants. Keywords: Macrosomia, Low birth weight, Prevalence, Etiology. *Corresponding Author: Dr. Masoomeh, Hematyar. Islamic Azad University, College of Medicine, Tehran, Iran. E-mail: [email protected]
Generating CRISPR-dCas9 System in Clostridium difficile Bacteria
No full textThe increasing incidence of Clostridium difficile-associated disease, and its resistance to a number of antibiotics, highlight the need for additional countermeasures. The main issue that hampers the design of antibiotics is a lack of appropriate tools to study the molecular biology of C.difficile in great detail. Insight into the function of DNA replication genes and the protein they encode might eventually lead to the development of specific inhibitors that can be exploited as drugs. By means of CRISPR-dCas9 system, we designed and engineered a construct that is capable of targeting specific replication genes and silence those genes. Our design is composed of a nuclease-deactivated Cas9 (dCas9) protein and a customized single-guided RNA (sgRNA) with a 20-basepair complementary region to target replication genes in C.difficile. Co-expression of dCas9 and sgRNA can efficiently block transcription by interfering with DNA replication process. We developed a set of conjugative plasmids that carries appropriate Pveg-sgRNA targets to repress CD0001 (dnaA) and CD1214 (spo0A) genes in C.difficile. We also built a construct with dCas9 and its inducible promoter (Pcpr) that can be conjugated into C.difficile. Once both constructs are transformed into C.difficile 630 erm, we will be able to analyze and detect potential phenotypes expressed in the presence of dCas9.Biomedical ElectronicsBiomedical EngineeringMechanical, Maritime and Materials Engineerin
Spherical geometry convection in a fluid with an Arrhenius thermal viscosity dependence: The impact of core size and surface temperature on the scaling of stagnant-lid thickness and internal temperature
No full textISSN:0031-9201ISSN:1872-7395ISSN:1872-739
Steel pipeline for the hydrogen storage and delivery: metallurgical viewpoint for Finnish ecosystem
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For more than a century, hydrogen has been used as an industrial chemical to produce ammonia for fertilizers and to process intermediate products in oil refineries. However, hydrogen has recently received renewed interest due to its ability to reduce carbon emissions to the atmosphere, particularly in the steel-making industries. Thus, hydrogen has the potential to play a critical role in combating climate change and achieving Finland's national goal of carbon neutrality by 2035. In this regard, national and global demand for hydrogen is rapidly increasing, and it is now three times more than what it was in 1975. The production and supply of hydrogen for industrial consumption would be a massive business that is expected to expand even faster than before. According to the IEA, the total demand for hydrogen in pure and mixed gas was approximately 115-120 million tones in 2018. (Gaseous) hydrogen can be efficiently transported by pipeline networks at a pressure of typically <100 bar. Pipelines provide an economical means of transporting hydrogen in large quantities over long/short distances, and hence they are often found serving end users who take hydrogen from a local central source of production. Nevertheless, the correct pipe material for hydrogen distribution must be designed and used, and the current natural gas pipeline infrastructure must be upgraded significantly if it is to be used for the delivery of pure hydrogen at high pressure. Hence, new research is needed to focus mainly on the possibility of use/modification of available natural gas pipeline network for hydrogen delivery as well as the study on the new economical pipeline material, exclusively for hydrogen transportation and storage.Abstract
For more than a century, hydrogen has been used as an industrial chemical to produce ammonia for fertilizers and to process intermediate products in oil refineries. However, hydrogen has recently received renewed interest due to its ability to reduce carbon emissions to the atmosphere, particularly in the steel-making industries. Thus, hydrogen has the potential to play a critical role in combating climate change and achieving Finland's national goal of carbon neutrality by 2035. In this regard, national and global demand for hydrogen is rapidly increasing, and it is now three times more than what it was in 1975. The production and supply of hydrogen for industrial consumption would be a massive business that is expected to expand even faster than before. According to the IEA, the total demand for hydrogen in pure and mixed gas was approximately 115-120 million tones in 2018. (Gaseous) hydrogen can be efficiently transported by pipeline networks at a pressure of typically <100 bar. Pipelines provide an economical means of transporting hydrogen in large quantities over long/short distances, and hence they are often found serving end users who take hydrogen from a local central source of production. Nevertheless, the correct pipe material for hydrogen distribution must be designed and used, and the current natural gas pipeline infrastructure must be upgraded significantly if it is to be used for the delivery of pure hydrogen at high pressure. Hence, new research is needed to focus mainly on the possibility of use/modification of available natural gas pipeline network for hydrogen delivery as well as the study on the new economical pipeline material, exclusively for hydrogen transportation and storage
Correction to: Fatigue assessment of the welded joints containing process relevant imperfections (Welding in the World, (2019), 63, 2, (249-261), 10.1007/s40194-018-00676-y)
No full textS.1903In the original version of this article the author René Fenzl is missing due to an oversight. The correct author list is as given in this correction.63Nr.
A rapid tectonic plate reorganization event driven by changes at subduction locations in a mantle convection model
No full textAbstract The occurrence of tectonic plate reorganization events is evident throughout the geologic record and appears to be associated with the cessation of mature and/or initiation of new subduction. Subduction initiation that produced the bend in the Hawaii-Emperor seamount chain resulted in the most recent upheaval of plate motion and engendered dramatic changes in plate velocities. Here, applying a method for identifying plate boundaries in a numerical global mantle convection model, we calculate Euler vector time series of self-consistently generated plates over a period of approximately 144 Myr. During this period, global evolution is characterized by two dominant convergent boundaries and the number of major plates identified varies between 9 and 14. Using a 2 Myr sampling rate to track the histories of three enduring plates that share a common triple junction, we observe a major plate reorganization event occurring over approximately 6-8 Myr. The catalyst for the event is identified as the development of a deep thermal feature intrinsic to internally heated convection. A buildup of heat enveloping a mature mantle downwelling accumulates a buoyancy that resists ongoing plate motion and eventually forces the over-riding plates on a new trajectory
The Influence of Rapid Tempering on the Mechanical and Microstructural Characteristics of 51CrV4 Steel
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The microstructure and mechanical properties of a low-alloy medium carbon steel (Fe-0.5C-0.9Mn-1Cr-0.16V, in wt.%) were investigated after rapid tempering and compared with a conventionally tempered counterpart. The conventional thermal cycle was performed in a laboratory-scale box furnace while rapid heat treatments were carried out using the Gleeble 3800 thermomechanical simulator machine. In the rapid heat treatments, the heating rate was 50 °C/s for austenitizing and 60 °C/s for the tempering process, with a cooling rate of 60 °C/s for both treatments. Austenitization was performed at 900 °C for 3 s and tempering was conducted at 300 °C and 500 °C for 2 s. For conventional routes, the heating rate for both austenitization and tempering was 5 °C/s. Likewise, the austenitization was carried out at 900 °C for 45 min and tempering was carried out at 300 °C and 500 °C for 30 min. The results revealed that rapid tempering resulted in a significantly increased impact toughness compared to conventional tempering, while maintaining a consistent high strength level. The quenched samples showed the highest hardness and tensile strength but obtained the lowest toughness values. The optimum combination of strength and toughness was achieved with the sample rapidly tempered at 300 °C, resulting in a tensile strength of 2050 MPa and impact energy of 14 J for sub-sized CVN samples. These desirable mechanical properties were achieved throughout the tempered martensitic microstructure with a minor fraction of pearlitic strings.Abstract
The microstructure and mechanical properties of a low-alloy medium carbon steel (Fe-0.5C-0.9Mn-1Cr-0.16V, in wt.%) were investigated after rapid tempering and compared with a conventionally tempered counterpart. The conventional thermal cycle was performed in a laboratory-scale box furnace while rapid heat treatments were carried out using the Gleeble 3800 thermomechanical simulator machine. In the rapid heat treatments, the heating rate was 50 °C/s for austenitizing and 60 °C/s for the tempering process, with a cooling rate of 60 °C/s for both treatments. Austenitization was performed at 900 °C for 3 s and tempering was conducted at 300 °C and 500 °C for 2 s. For conventional routes, the heating rate for both austenitization and tempering was 5 °C/s. Likewise, the austenitization was carried out at 900 °C for 45 min and tempering was carried out at 300 °C and 500 °C for 30 min. The results revealed that rapid tempering resulted in a significantly increased impact toughness compared to conventional tempering, while maintaining a consistent high strength level. The quenched samples showed the highest hardness and tensile strength but obtained the lowest toughness values. The optimum combination of strength and toughness was achieved with the sample rapidly tempered at 300 °C, resulting in a tensile strength of 2050 MPa and impact energy of 14 J for sub-sized CVN samples. These desirable mechanical properties were achieved throughout the tempered martensitic microstructure with a minor fraction of pearlitic strings
Identifying Effective Factors and Obstacles Using Electronic Learning to Increase Mental Health of Primary School Students in Karaj (A Qualitative Study)
No full textBackground and Objective:At first glance to the science of educational technology, what usually comes to mind, is the application of new technologies in the education of learners, such a belief indicates a mechanical approach to the scope of technology and education. But experts see educational technology as more than just the use of educational tools. They believe that educational technology includes a systematic approach, design, implementation, evaluation and problem solving of educational programs and the simultaneous use of human and inhuman resources, and its ultimate goal is deep, sustainable and effective learning. e-learning is the result of the use of new technologies in education and is one of the inductive methods of teaching learning in which the subject starts from presenting a specific observation or a subject and the audience hypothesizes, collects information, combines information and discovers the problem. e-learning is introduced as an online process by which learning can be done using the Internet and web pages. The teacher can design a new e-space or use the e-learning environments available on the Internet in connection with any of the subjects. The purpose of this study was identifying effective factors and obstacles in using e-learning of primary school students in Karaj. Methods: The present study is a qualitative research and utilized a focus group method. The research instrument was semi-structured interview. By applying the focus group method, the data were gathered through interviewing 29 experts and specialized teachers in the area of e-learning in three stages including Open Source (Primary), Axial and Selective (Optional) Coding. Findings:Open codes were consisted of 75 concepts, and axial codes were compromised of nine categories including organizational elements, information literacy, technology, educational design, beneficiaries, educational sources, environmental factors, limitations and attitude factors. In the area of the barriers and problems in using e-learning, 48 core concepts and codes wererecognized as the axial code of thepresent study in nine categories including structural and organizational obstacles, lack of required training for teachers, weakness of students, inconformity of the current curriculum with information and communication technology, no satisfactory management, no precise goal and objective, cultural conditions and hindrances, lack of appropriate incentive system, space and equipment. Conclusion: Research show that as a learner-centered learning method, e-learning facilitates and enhances high-level cognitive skills such as analysis, synthesis, evaluation and judgment, critical thinking, search and problem solving. Therefore, it is suggested to pay attention to all levels of learning. If the ministry of education fails to provide the necessary infrastructure for the development of e-learning, they will certainly face various challenges. It is recommended to provide the necessary infrastructure for all schools in the country in all provinces. ===================================================================================== COPYRIGHTS ©2019 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers. ====================================================================================
