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Sample records for inadequate cognitive scaffold

  1. Cognitive Attributes of Adequate and Inadequate Responders to Reading Intervention in Middle School

    Science.gov (United States)

    Miciak, Jeremy; Stuebing, Karla K.; Vaughn, Sharon; Roberts, Greg; Barth, Amy E.; Fletcher, Jack M.

    2014-01-01

    No studies have investigated the cognitive attributes of middle school students who are adequate and inadequate responders to Tier 2 reading intervention. We compared students in Grades 6 and 7 representing groups of adequate responders (n = 77) and inadequate responders who fell below criteria in (a) comprehension (n = 54); (b) fluency (n = 45);…

  2. Cognitive Attributes of Adequate and Inadequate Responders to Reading Intervention in Middle School

    OpenAIRE

    Miciak, Jeremy; Stuebing, Karla K.; Vaughn, Sharon; Roberts, Greg; Barth, Amy Elizabeth; Fletcher, Jack M.

    2014-01-01

    No studies have investigated the cognitive attributes of middle school students who are adequate and inadequate responders to Tier 2 reading intervention. We compared students in Grades 6 and 7 representing groups of adequate responders (n = 77) and inadequate responders who fell below criteria in (a) comprehension (n = 54); (b) fluency (n = 45); and (c) decoding, fluency, and comprehension (DFC; n = 45). These students received measures of phonological awareness, listening comprehension, rap...

  3. Cognitive Dissonance, Confirmatory Bias and Inadequate Information Processing: Evidence from Experimental Auctions

    OpenAIRE

    Cao, Ying; Just, David R.; Wansink, Brian

    2014-01-01

    Using psychological terms such as cognitive dissonance and confirmation bias, this study reveals how individual consumers inadequately process (food safety) information, pay limited attention to signals, and make purchase decisions that are bias towards their initial choices. While it is expected that reading extra information about potential risk associated with the food decreases consumers' willingness to pay (WTP), the magnitude of the impact varies across individuals. In general, consumer...

  4. A Framework for Designing Scaffolds That Improve Motivation and Cognition

    Science.gov (United States)

    Belland, Brian R.; Kim, ChanMin; Hannafin, Michael J.

    2013-01-01

    A problematic, yet common, assumption among educational researchers is that when teachers provide authentic, problem-based experiences, students will automatically be engaged. Evidence indicates that this is often not the case. In this article, we discuss (a) problems with ignoring motivation in the design of learning environments, (b) problem-based learning and scaffolding as one way to help, (c) how scaffolding has strayed from what was originally equal parts motivational and cognitive support, and (d) a conceptual framework for the design of scaffolds that can enhance motivation as well as cognitive outcomes. We propose guidelines for the design of computer-based scaffolds to promote motivation and engagement while students are solving authentic problems. Remaining questions and suggestions for future research are then discussed. PMID:24273351

  5. Scaffolding Cognitive Processes in a Marketing Curriculum

    Science.gov (United States)

    Milliken, John

    2007-01-01

    This article highlights the importance of improving the cognitive processes of students in business studies today. When developing a curriculum in business studies at higher education level, thorough consideration should be given to all components of the learning and assessment processes. They should be tailored to real world dynamics so that they…

  6. Reproducing American Sign Language Sentences: Cognitive Scaffolding in Working Memory

    Directory of Open Access Journals (Sweden)

    Ted eSupalla

    2014-08-01

    Full Text Available The American Sign Language Sentence Reproduction Test (ASL-SRT requires the precise reproduction of a series of ASL sentences increasing in complexity and length. Error analyses of such tasks provides insight into working memory and scaffolding processes. Data was collected from three groups expected to differ in fluency: deaf children, deaf adults and hearing adults, all users of ASL. Quantitative (correct/incorrect recall and qualitative error analyses were performed. Percent correct on the reproduction task supports its sensitivity to fluency as test performance clearly differed across the three groups studied. A linguistic analysis of errors further documented differing strategies and bias across groups. Subjects’ recall projected the affordance and constraints of deep linguistic representations to differing degrees, with subjects resorting to alternate processing strategies in the absence of linguistic knowledge. A qualitative error analysis allows us to capture generalizations about the relationship between error pattern and the cognitive scaffolding, which governs the sentence reproduction process. Highly fluent signers and less-fluent signers share common chokepoints on particular words in sentences. However, they diverge in heuristic strategy. Fluent signers, when they make an error, tend to preserve semantic details while altering morpho-syntactic domains. They produce syntactically correct sentences with equivalent meaning to the to-be-reproduced one, but these are not verbatim reproductions of the original sentence. In contrast, less-fluent signers tend to use a more linear strategy, preserving lexical status and word ordering while omitting local inflections, and occasionally resorting to visuo-motoric imitation. Thus, whereas fluent signers readily use top-down scaffolding in their working memory, less fluent signers fail to do so. Implications for current models of working memory across spoken and signed modalities are

  7. Gait and Cognition in Parkinson’s Disease: Cognitive Impairment Is Inadequately Reflected by Gait Performance during Dual Task

    Directory of Open Access Journals (Sweden)

    Heiko Gaßner

    2017-10-01

    Full Text Available IntroductionCognitive and gait deficits are common symptoms in Parkinson’s disease (PD. Motor-cognitive dual tasks (DTs are used to explore the interplay between gait and cognition. However, it is unclear if DT gait performance is indicative for cognitive impairment. Therefore, the aim of this study was to investigate if cognitive deficits are reflected by DT costs of spatiotemporal gait parameters.MethodsCognitive function, single task (ST and DT gait performance were investigated in 67 PD patients. Cognition was assessed by the Montreal Cognitive Assessment (MoCA followed by a standardized, sensor-based gait test and the identical gait test while subtracting serial 3’s. Cognitive impairment was defined by a MoCA score <26. DT costs in gait parameters [(DT − ST/ST × 100] were calculated as a measure of DT effect on gait. Correlation analysis was used to evaluate the association between MoCA performance and gait parameters. In a linear regression model, DT gait costs and clinical confounders (age, gender, disease duration, motor impairment, medication, and depression were correlated to cognitive performance. In a subgroup analysis, we compared matched groups of cognitively impaired and unimpaired PD patients regarding differences in ST, DT, and DT gait costs.ResultsCorrelation analysis revealed weak correlations between MoCA score and DT costs of gait parameters (r/rSp ≤ 0.3. DT costs of stride length, swing time variability, and maximum toe clearance (|r/rSp| > 0.2 were included in a regression analysis. The parameters only explain 8% of the cognitive variance. In combination with clinical confounders, regression analysis showed that these gait parameters explained 30% of MoCA performance. Group comparison revealed strong DT effects within both groups (large effect sizes, but significant between-group effects in DT gait costs were not observed.ConclusionThese findings suggest that DT gait performance is not indicative

  8. Maternal scaffolding in a disadvantaged global context: The influence of working memory and cognitive capacities.

    Science.gov (United States)

    Obradović, Jelena; Portilla, Ximena A; Tirado-Strayer, Nicole; Siyal, Saima; Rasheed, Muneera A; Yousafzai, Aisha K

    2017-03-01

    The current study focuses on maternal cognitive capacities as determinants of parenting in a highly disadvantaged global context, where children's experiences at home are often the 1st and only opportunity for learning and intellectual growth. In a large sample of 1,291 biological mothers of preschool-aged children in rural Pakistan, we examined the unique association of maternal working memory skills (independent of related cognitive capacities) with cognitively stimulating parenting behaviors. Path analysis revealed that directly assessed working memory, short-term memory, and verbal intelligence independently predicted greater levels of observed maternal scaffolding behaviors. Mothers from poorer families demonstrated lower levels of working memory, short-term memory, and verbal intelligence. However, mothers' participation in an early childhood parenting intervention that ended 2 years prior to this study contributed to greater levels of working memory skills and verbal intelligence. Further, all 3 domains of maternal cognitive capacity mediated the effect of family economic resources on maternal scaffolding, and verbal intelligence also mediated the effect of early parenting intervention exposure on maternal scaffolding. The study demonstrates the unique relevance of maternal working memory for scaffolding behaviors that required continuously monitoring the child's engagement, providing assistance, and minimizing external distractions. These results highlight the importance of directly targeting maternal cognitive capacities in poor women with little or no formal education, using a 2-generation intervention approach that includes activities known to promote parental executive functioning and literacy. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  9. The Relationship of Scaffolding on Cognitive Load in an Online Self-Regulated Learning Environment

    Science.gov (United States)

    Danilenko, Eugene Paul

    2010-01-01

    Scaffolding learners in self-regulated learning environments is a topic of increasing importance as implementation of online learning grows. Since cognitive overload in hypermedia environments can be a problem for some learners, instructional design strategies can be used to decrease extraneous load or encourage germane load in order to help…

  10. Helping Students with Cognitive Disabilities Improve Social Writing Skills through Email Modeling and Scaffolding

    Science.gov (United States)

    Wang, Xiao-lei; Eberhard, Dominique; Voron, Mike; Bernas, Ronan

    2016-01-01

    The purpose of this study is to examine the effects of email modeling and scaffolding on the social writing quality of students with cognitive disabilities. Ten students from a university-affiliated lab school (mean age = 19.3; SD = 1.2) with an average of IQ of 55.30 (SD = 5.98) and 10 teacher candidates in a university teacher education…

  11. Technology Mediated Instruction and its Effect on Cognitive Scaffolding, motivation and Academic Performance in EFL Context

    Directory of Open Access Journals (Sweden)

    Sepideh Berenji

    2017-11-01

    Full Text Available Technology mediated learning brings together the users with shared interests. This method makes learners informally engaged in language learning. This study intended to investigate the effect of technology mediated instruction on cognitive scaffolding, academic performance and motivation. Employing a quasi-experimental research, 80 learners from two intact classes at Islamic Azad University, Osku Branch were selected as the experimental and control groups. Telegram as a tool was used in the experimental group, while the control group received traditional way of instruction. Critical ethnography approach was implemented to consider the amount of cognitive scaffolding. To measure the students’ motivational level in both groups, Course Interest Survey (CIS was administered at the end of the semester. The total average score for each group was calculated. To compare students’ academic achievement, their average scores in the final academic test were considered. An Independent samples t-test in was used to compare the mean scores. The results indicated that technology mediated learning brought about cognitive scaffolding and the students in the experimental group outperformed the control group in terms of motivation and academic achievement. The results of the study suggest that to bring about academically successful students, practitioners should use technology mediated instruction.

  12. Effect of Motivational Scaffolding on E-Learning Environments: Self-Efficacy, Learning Achievement, and Cognitive Style

    Science.gov (United States)

    Valencia-Vallejo, Nilson; López-Vargas, Omar; Sanabria-Rodríguez, Luis

    2018-01-01

    The present research studies the effects of motivational scaffolding that favor self-efficacy and improve learning achievement in students with different cognitive styles in the Field Dependence/Independence (FDI) dimension, when they interact in an e-learning environment on mathematics. The research has an experimental design with two groups and…

  13. Development Scaffolding for Construction of Evaluation Instrument Training Program on The Cognitive Domain For Senior High School Physics Teachers and The Same Level

    Science.gov (United States)

    Arif, W.; Suhandi, A.; Kaniawati, I.; Setiawan, A.

    2017-02-01

    The development of scaffolding for evaluation instrument construction training program on the cognitive domain for senior high school physics teacher and the same level that is specified in the test instrument has been done. This development was motivated by the low ability of the majority of physics teachers in constructing the physics learning achievement test. This situation not in accordance with the demands of Permendiknas RI no. 16 tahun 2007 concerning the standard of academic qualifications and competence of teachers, stating that teachers should have a good ability to develop instruments for assessment and evaluation of process and learning outcomes. Based on the preliminary study results, it can be seen that the main cause of the inability of teachers in developing physics achievement test is because they do not good understand of the indicators for each aspect of cognitive domains. Scaffolding development is done by using the research and development methods formulated by Thiagarajan which includes define, design and develope steps. Develop step includes build the scaffolding, validation of scaffolding by experts and the limited pilot implementations on the training activities. From the build scaffolding step, resulted the scaffolding for the construction of test instruments training program which include the process steps; description of indicators, operationalization of indicators, construction the itemsframework (items scenarios), construction the items stem, construction the items and checking the items. The results of the validation by three validator indicates that the built scaffolding are suitable for use in the construction of physics achievement test training program, especially for novice. The limited pilot implementation of the built scaffolding conducted in training activities attended by 10 senior high school physics teachers in Garut district. The results of the limited pilot implementation shows that the built scaffolding have a medium

  14. A Bayesian Network Meta-Analysis to Synthesize the Influence of Contexts of Scaffolding Use on Cognitive Outcomes in STEM Education

    Science.gov (United States)

    Belland, Brian R.; Walker, Andrew E.; Kim, Nam Ju

    2017-01-01

    Computer-based scaffolding provides temporary support that enables students to participate in and become more proficient at complex skills like problem solving, argumentation, and evaluation. While meta-analyses have addressed between-subject differences on cognitive outcomes resulting from scaffolding, none has addressed within-subject gains. This leaves much quantitative scaffolding literature not covered by existing meta-analyses. To address this gap, this study used Bayesian network meta-analysis to synthesize within-subjects (pre–post) differences resulting from scaffolding in 56 studies. We generated the posterior distribution using 20,000 Markov Chain Monte Carlo samples. Scaffolding has a consistently strong effect across student populations, STEM (science, technology, engineering, and mathematics) disciplines, and assessment levels, and a strong effect when used with most problem-centered instructional models (exception: inquiry-based learning and modeling visualization) and educational levels (exception: secondary education). Results also indicate some promising areas for future scaffolding research, including scaffolding among students with learning disabilities, for whom the effect size was particularly large (ḡ = 3.13). PMID:29200508

  15. Inadequate housing in Ghana

    Directory of Open Access Journals (Sweden)

    Franklin Obeng-Odoom

    2011-01-01

    Full Text Available Two themes are evident in housing research in Ghana. One involves the study of how to increase the number of dwellings to correct the overall housing deficit, and the other focuses on how to improve housing for slum dwellers. Between these two extremes, there is relatively little research on why the existing buildings are poorly maintained. This paper is based on a review of existing studies on inadequate housing. It synthesises the evidence on the possible reasons for this neglect, makes a case for better maintenance and analyses possible ways of reversing the problem of inadequate housing.

  16. Scaffolding the design of accessible eLearning content: a user-centered approach and cognitive perspective.

    Science.gov (United States)

    Catarci, Tiziana; De Giovanni, Loredana; Gabrielli, Silvia; Kimani, Stephen; Mirabella, Valeria

    2008-08-01

    There exist various guidelines for facilitating the design, preparation, and deployment of accessible eLearning applications and contents. However, such guidelines prevalently address accessibility in a rather technical sense, without giving sufficient consideration to the cognitive aspects and issues related to the use of eLearning materials by learners with disabilities. In this paper we describe how a user-centered design process was applied to develop a method and set of guidelines for didactical experts to scaffold their creation of accessible eLearning content, based on a more sound approach to accessibility. The paper also discusses possible design solutions for tools supporting eLearning content authors in the adoption and application of the proposed approach.

  17. Barriers to Mammography among Inadequately Screened Women

    Science.gov (United States)

    Stoll, Carolyn R. T.; Roberts, Summer; Cheng, Meng-Ru; Crayton, Eloise V.; Jackson, Sherrill; Politi, Mary C.

    2015-01-01

    Mammography use has increased over the past 20 years, yet more than 30% of women remain inadequately screened. Structural barriers can deter individuals from screening, however, cognitive, emotional, and communication barriers may also prevent mammography use. This study sought to identify the impact of number and type of barriers on mammography…

  18. Effects of Faded Scaffolding in Computer-Based Instruction on Learners' Performance, Cognitive Load, and Test Anxiety

    Science.gov (United States)

    Hao, Shuang

    2016-01-01

    Scaffolding is a type of instructional support that helps students to complete a learning task that exceeds their current ability. Scaffolding plays an important role in augmenting other instructional approaches, such as problem-based learning, and facilitates gradual shifts of responsibility from the more advanced others to the learner (Belland,…

  19. Semiotic Scaffolding in Mathematics

    DEFF Research Database (Denmark)

    Johansen, Mikkel Willum; Misfeldt, Morten

    2015-01-01

    This paper investigates the notion of semiotic scaffolding in relation to mathematics by considering its influence on mathematical activities, and on the evolution of mathematics as a research field. We will do this by analyzing the role different representational forms play in mathematical...... cognition, and more broadly on mathematical activities. In the main part of the paper, we will present and analyze three different cases. For the first case, we investigate the semiotic scaffolding involved in pencil and paper multiplication. For the second case, we investigate how the development of new...... in both mathematical cognition and in the development of mathematics itself, but mathematical cognition cannot itself be reduced to the use of semiotic scaffolding....

  20. Distributed Cognition as a Lens to Understand the Effects of Scaffolds: The Role of Transfer of Responsibility

    Science.gov (United States)

    Belland, Brian R.

    2011-01-01

    Problem solving is an important skill in the knowledge economy. Research indicates that the development of problem solving skills works better in the context of instructional approaches centered on real-world problems. But students need scaffolding to be successful in such instruction. In this paper I present a conceptual framework for…

  1. Consequences of Inadequate Physical Activity

    Centers for Disease Control (CDC) Podcasts

    2018-03-27

    Listen as CDC Epidemiologist Susan Carlson, PhD, talks about her research, which estimates the percentage of US deaths attributed to inadequate levels of physical activity.  Created: 3/27/2018 by Preventing Chronic Disease (PCD), National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 3/27/2018.

  2. Radiologists' responses to inadequate referrals

    International Nuclear Information System (INIS)

    Lysdahl, Kristin Bakke; Hofmann, Bjoern Morten; Espeland, Ansgar

    2010-01-01

    To investigate radiologists' responses to inadequate imaging referrals. A survey was mailed to Norwegian radiologists; 69% responded. They graded the frequencies of actions related to referrals with ambiguous indications or inappropriate examination choices and the contribution of factors preventing and not preventing an examination of doubtful usefulness from being performed as requested. Ninety-five percent (344/361) reported daily or weekly actions related to inadequate referrals. Actions differed among subspecialties. The most frequent were contacting the referrer to clarify the clinical problem and checking test results/information in the medical records. Both actions were more frequent among registrars than specialists and among hospital radiologists than institute radiologists. Institute radiologists were more likely to ask the patient for additional information and to examine the patient clinically. Factors rated as contributing most to prevent doubtful examinations were high risk of serious complications/side effects, high radiation dose and low patient age. Factors facilitating doubtful examinations included respect for the referrer's judgment, patient/next-of-kin wants the examination, patient has arrived, unreachable referrer, and time pressure. In summary, radiologists facing inadequate referrals considered patient safety and sought more information. Vetting referrals on arrival, easier access to referring clinicians, and time for radiologists to handle inadequate referrals may contribute to improved use of imaging. (orig.)

  3. Scaffolding Writing Using Feedback in Students' Graphic Organizers--Novice Writers' Relevance of Ideas and Cognitive Loads

    Science.gov (United States)

    Lee, Chien Ching; Tan, Seng Chee

    2010-01-01

    This paper aims to find out two outcomes of feedback in the novice writers' graphic organizers, which are the novice writers' ability to align their ideas to their writing goal, and their perceived germane, metacognitive, extraneous and intrinsic cognitive loads when generating and revising ideas based on the feedback. Data was gathered from the…

  4. Scaffolded biology.

    Science.gov (United States)

    Minelli, Alessandro

    2016-09-01

    Descriptions and interpretations of the natural world are dominated by dichotomies such as organism vs. environment, nature vs. nurture, genetic vs. epigenetic, but in the last couple of decades strong dissatisfaction with those partitions has been repeatedly voiced and a number of alternative perspectives have been suggested, from perspectives such as Dawkins' extended phenotype, Turner's extended organism, Oyama's Developmental Systems Theory and Odling-Smee's niche construction theory. Last in time is the description of biological phenomena in terms of hybrids between an organism (scaffolded system) and a living or non-living scaffold, forming unit systems to study processes such as reproduction and development. As scaffold, eventually, we can define any resource used by the biological system, especially in development and reproduction, without incorporating it as happens in the case of resources fueling metabolism. Addressing biological systems as functionally scaffolded systems may help pointing to functional relationships that can impart temporal marking to the developmental process and thus explain its irreversibility; revisiting the boundary between development and metabolism and also regeneration phenomena, by suggesting a conceptual framework within which to investigate phenomena of regular hypermorphic regeneration such as characteristic of deer antlers; fixing a periodization of development in terms of the times at which a scaffolding relationship begins or is terminated; and promoting plant galls to legitimate study objects of developmental biology.

  5. Semiotic scaffolding

    DEFF Research Database (Denmark)

    Hoffmeyer, Jesper

    2015-01-01

    Life processes at all levels (from the genetic to the behavioral) are coordinated by semiotic interactions between cells, tissues, membranes, organs, or individuals and tuned through evolution to stabilize important functions. A stabilizing dynamics based on a system of semiotic scaffoldings impl...... semiotic scaffolding is not, of course, exclusive for phylogenetic and ontogenetic development, it is also an important dynamical element in cultural evolution.......Life processes at all levels (from the genetic to the behavioral) are coordinated by semiotic interactions between cells, tissues, membranes, organs, or individuals and tuned through evolution to stabilize important functions. A stabilizing dynamics based on a system of semiotic scaffoldings...... (the representamen) and the effect. Semiotic interaction patterns therefore provide fast and versatile mechanisms for adaptations, mechanisms that depend on communication and “learning” rather than on genetic preformation. Seen as a stabilizing agency supporting the emergence of higher-order structure...

  6. Scaffolding students’ assignments

    DEFF Research Database (Denmark)

    Slot, Marie Falkesgaard

    2013-01-01

    This article discusses scaffolding in typical student assignments in mother tongue learning materials in upper secondary education in Denmark and the United Kingdom. It has been determined that assignments do not have sufficient scaffolding end features to help pupils understand concepts and build...... objects. The article presents the results of empirical research on tasks given in Danish and British learning materials. This work is based on a further development of my PhD thesis: “Learning materials in the subject of Danish” (Slot 2010). The main focus is how cognitive models (and subsidiary explicit...... learning goals) can help students structure their argumentative and communica-tive learning processes, and how various multimodal representations can give more open-ended learning possibilities for collaboration. The article presents a short introduction of the skills for 21st century learning and defines...

  7. Developmental Scaffolding

    DEFF Research Database (Denmark)

    Giorgi, Franco; Bruni, Luis Emilio

    2015-01-01

    . Within the developmental hierarchy, each module yields an inter-level relationship that makes it possible for the scaffolding to mediate the production of selectable variations. Awide range of genetic, cellular and morphological mechanisms allows the scaffolding to integrate these modular variations...... to the complexity of sign recognition proper of a cellular community. In this semiotic perspective, the apparent goal directness of any developmental strategy should no longer be accounted for by a predetermined genetic program, but by the gradual definition of the relationships selected amongst the ones...

  8. Radiologists' responses to inadequate referrals

    Energy Technology Data Exchange (ETDEWEB)

    Lysdahl, Kristin Bakke [Oslo University College, Faculty of Health Sciences, Oslo (Norway); University of Oslo, Section for Medical Ethics, Faculty of Medicine, P.O. Box 1130, Blindern, Oslo (Norway); Hofmann, Bjoern Morten [University of Oslo, Section for Medical Ethics, Faculty of Medicine, P.O. Box 1130, Blindern, Oslo (Norway); Gjoevik University College, Faculty of Health Care and Nursing, Gjoevik (Norway); Espeland, Ansgar [Haukeland University Hospital, Department of Radiology, Bergen (Norway); University of Bergen, Section for Radiology, Department of Surgical Sciences, Bergen (Norway)

    2010-05-15

    To investigate radiologists' responses to inadequate imaging referrals. A survey was mailed to Norwegian radiologists; 69% responded. They graded the frequencies of actions related to referrals with ambiguous indications or inappropriate examination choices and the contribution of factors preventing and not preventing an examination of doubtful usefulness from being performed as requested. Ninety-five percent (344/361) reported daily or weekly actions related to inadequate referrals. Actions differed among subspecialties. The most frequent were contacting the referrer to clarify the clinical problem and checking test results/information in the medical records. Both actions were more frequent among registrars than specialists and among hospital radiologists than institute radiologists. Institute radiologists were more likely to ask the patient for additional information and to examine the patient clinically. Factors rated as contributing most to prevent doubtful examinations were high risk of serious complications/side effects, high radiation dose and low patient age. Factors facilitating doubtful examinations included respect for the referrer's judgment, patient/next-of-kin wants the examination, patient has arrived, unreachable referrer, and time pressure. In summary, radiologists facing inadequate referrals considered patient safety and sought more information. Vetting referrals on arrival, easier access to referring clinicians, and time for radiologists to handle inadequate referrals may contribute to improved use of imaging. (orig.)

  9. Italian retail gasoline activities: inadequate distribution network

    International Nuclear Information System (INIS)

    Verde, Stefano

    2005-01-01

    It is common belief that competition in the Italian retail gasoline activities is hindered by oil companies' collusive behaviour. However, when developing a broader analysis of the sector, low efficiency and scarce competition could results as the consequences coming from an inadequate distribution network and from the recognition of international markets and focal point [it

  10. Evidence Report: Risk Factor of Inadequate Nutrition

    Science.gov (United States)

    Smith, Scott M.; Zwart, Sara R.; Heer, Martina

    2015-01-01

    The importance of nutrition in exploration has been documented repeatedly throughout history, where, for example, in the period between Columbus' voyage in 1492 and the invention of the steam engine, scurvy resulted in more sailor deaths than all other causes of death combined. Because nutrients are required for the structure and function of every cell and every system in the body, defining the nutrient requirements for spaceflight and ensuring provision and intake of those nutrients are primary issues for crew health and mission success. Unique aspects of nutrition during space travel include the overarching physiological adaptation to weightlessness, psychological adaptation to extreme and remote environments, and the ability of nutrition and nutrients to serve as countermeasures to ameliorate the negative effects of spaceflight on the human body. Key areas of clinical concern for long-duration spaceflight include loss of body mass (general inadequate food intake), bone and muscle loss, cardiovascular and immune system decrements, increased radiation exposure and oxidative stress, vision and ophthalmic changes, behavior and performance, nutrient supply during extravehicular activity, and general depletion of body nutrient stores because of inadequate food supply, inadequate food intake, increased metabolism, and/or irreversible loss of nutrients. These topics are reviewed herein, based on the current gap structure.

  11. Inadequate Evidence for Multiple Intelligences, Mozart Effect, and Emotional Intelligence Theories

    Science.gov (United States)

    Waterhouse, Lynn

    2006-01-01

    I (Waterhouse, 2006) argued that, because multiple intelligences, the Mozart effect, and emotional intelligence theories have inadequate empirical support and are not consistent with cognitive neuroscience findings, these theories should not be applied in education. Proponents countered that their theories had sufficient empirical support, were…

  12. Semiotic scaffolding

    DEFF Research Database (Denmark)

    Hoffmeyer, Jesper

    2014-01-01

    that is still widely held by scientists and thinkers of today. Replacing sensory mechanics with sensory semiotics opens hitherto not fully explored ways of integrating life and cognition. Human interaction is embedded in semiotic activity that easily penetrates to processes deep in the body and brain and back......While organic life is the product of myriads of biochemical processes it usually escapes notice that the chemistry of life cannot be understood exclusively in terms of chemistry. What must be added is an understanding of the particular organized dynamics, which makes the integration of all...... these processes into real living creatures possible. This dynamics, however, is not itself part of chemistry, but is evolutionarily tailored to suit a communicative or semiotic (=sign theoretical) logic (Hoffmeyer 2008). Reframing our biological thinking in terms of semiotics, i.e., biosemiotics, deeply...

  13. Evidence Report: Risk of Inadequate Human-Computer Interaction

    Science.gov (United States)

    Holden, Kritina; Ezer, Neta; Vos, Gordon

    2013-01-01

    Human-computer interaction (HCI) encompasses all the methods by which humans and computer-based systems communicate, share information, and accomplish tasks. When HCI is poorly designed, crews have difficulty entering, navigating, accessing, and understanding information. HCI has rarely been studied in an operational spaceflight context, and detailed performance data that would support evaluation of HCI have not been collected; thus, we draw much of our evidence from post-spaceflight crew comments, and from other safety-critical domains like ground-based power plants, and aviation. Additionally, there is a concern that any potential or real issues to date may have been masked by the fact that crews have near constant access to ground controllers, who monitor for errors, correct mistakes, and provide additional information needed to complete tasks. We do not know what types of HCI issues might arise without this "safety net". Exploration missions will test this concern, as crews may be operating autonomously due to communication delays and blackouts. Crew survival will be heavily dependent on available electronic information for just-in-time training, procedure execution, and vehicle or system maintenance; hence, the criticality of the Risk of Inadequate HCI. Future work must focus on identifying the most important contributing risk factors, evaluating their contribution to the overall risk, and developing appropriate mitigations. The Risk of Inadequate HCI includes eight core contributing factors based on the Human Factors Analysis and Classification System (HFACS): (1) Requirements, policies, and design processes, (2) Information resources and support, (3) Allocation of attention, (4) Cognitive overload, (5) Environmentally induced perceptual changes, (6) Misperception and misinterpretation of displayed information, (7) Spatial disorientation, and (8) Displays and controls.

  14. Inadequate Nutritional Status of Hospitalized Cancer Patients

    Directory of Open Access Journals (Sweden)

    Ali Alkan

    2017-03-01

    Full Text Available Objective: In oncology practice, nutrition and also metabolic activity are essential to support the nutritional status and prevent malignant cachexia. It is important to evaluate the patients and plan the maneuvers at the start of the therapy. The primary objective of the study is to define the nutritional status of hospitalized patients and the factors affecting it in order to define the most susceptible patients and maneuvers for better nutritional support. Methods: Patients hospitalized in oncology clinic for therapy were evaluated for food intake and nutritional status through structured interviews. The clinical properties, medical therapies, elements of nutritional support were noted and predictors of inadequate nutritional status (INS were analyzed. Results: Four hundred twenty three patients, between 16-82 years old (median: 52 were evaluated. Nearly half of the patients (185, 43% reported a better appetite at home than in hospital and declared that hospitalization is an important cause of loss of appetite (140/185, 75.6%. Presence of nausea/vomiting (N/V, depression, age less than 65 and use of non-steroidal anti-inflammatory drugs (NSAIDs were associated with increased risk of INS in hospitalized cancer patients. On the contrary, steroid medication showed a positive impact on nutritional status of cancer patients. Conclusion: N/V, younger age, presence of depression and NSAIDs medication were associated with INS in hospitalized cancer patients. Clinicians should pay more attention to this group of patients. In addition, unnecessary hospitalizations and medications that may disturb oral intake must be avoided. Corticosteroids are important tools for managing anorexia and INS.

  15. Scaffold architecture and fibrin gels promote meniscal cell proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Pawelec, K. M., E-mail: pawelec.km@gmail.com, E-mail: jw626@cam.ac.uk; Best, S. M.; Cameron, R. E. [Cambridge Centre for Medical Materials, Materials Science and Metallurgy Department, University of Cambridge, Cambridge CB3 0FS (United Kingdom); Wardale, R. J., E-mail: pawelec.km@gmail.com, E-mail: jw626@cam.ac.uk [Division of Trauma and Orthopaedic Surgery, Department of Surgery, University of Cambridge, Cambridge CB2 2QQ (United Kingdom)

    2015-01-01

    Stability of the knee relies on the meniscus, a complex connective tissue with poor healing ability. Current meniscal tissue engineering is inadequate, as the signals for increasing meniscal cell proliferation have not been established. In this study, collagen scaffold structure, isotropic or aligned, and fibrin gel addition were tested. Metabolic activity was promoted by fibrin addition. Cellular proliferation, however, was significantly increased by both aligned architectures and fibrin addition. None of the constructs impaired collagen type I production or triggered adverse inflammatory responses. It was demonstrated that both fibrin gel addition and optimized scaffold architecture effectively promote meniscal cell proliferation.

  16. Cognitive biology dealing with information from bacteria to minds

    CERN Document Server

    Auletta, Gennaro

    2011-01-01

    Providing a new conceptual scaffold for further research in biology and cognition, this text introduces the new field of cognitive biology, treating developing organisms as information processors which use cognition to control and modify their environments.

  17. Inadequate control of world's radioactive sources

    International Nuclear Information System (INIS)

    2002-01-01

    The radioactive materials needed to build a 'dirty bomb' can be found in almost any country in the world, and more than 100 countries may have inadequate control and monitoring programs necessary to prevent or even detect the theft of these materials. The IAEA points out that while radioactive sources number in the millions, only a small percentage have enough strength to cause serious radiological harm. It is these powerful sources that need to be focused on as a priority. In a significant recent development, the IAEA, working in collaboration with the United States Department of Energy (DOE) and the Russian Federation's Ministry for Atomic Energy (MINATOM), have established a tripartite working group on 'Securing and Managing Radioactive Sources'. Through its program to help countries improve their national infrastructures for radiation safety and security, the IAEA has found that more than 100 countries may have no minimum infrastructure in place to properly control radiation sources. However, many IAEA Member States - in Africa, Asia, Latin America, and Europe - are making progress through an IAEA project to strengthen their capabilities to control and regulate radioactive sources. The IAEA is also concerned about the over 50 countries that are not IAEA Member States (there are 134), as they do not benefit from IAEA assistance and are likely to have no regulatory infrastructure. The IAEA has been active in lending its expertise to search out and secure orphaned sources in several countries. More than 70 States have joined with the IAEA to collect and share information on trafficking incidents and other unauthorized movements of radioactive sources and other radioactive materials. The IAEA and its Member States are working hard to raise levels of radiation safety and security, especially focusing on countries known to have urgent needs. The IAEA has taken the leading role in the United Nations system in establishing standards of safety, the most significant of

  18. Aging Ergonomics: A Field with Inadequate Notice

    Directory of Open Access Journals (Sweden)

    Saeed Ghaneh

    2016-12-01

    Full Text Available World population aging is a phenomenon we are confronting with, more than past. This fact has different implications for today’s societies. One of these aspects is workforce (1. Some factors have resulted in more tendencies of workers to remain in their works including: Economic, societal, cultural factors, and social trends and laws such as increasing age of retirement in the middle twentieth century, which recently increased more (2.      Productive workforce is one of major assets of each country. So, in one hand we have older adults in our workplaces and in other hand, we are following to retain employee’s productivity at first, and then, improve it. Ergonomics as a multidisciplinary science, attempts to make balance between human capabilities and its limitations by fitting the task to the person or fitting the person to the task. In this way, workers’ fatigue and errors are minimized and productivity and well-being optimized (3.     In more developed countries like United States, approximately 66.3 percent of adults aged 55-64 years are in the workforce (4. In our country, Iran, 7.3% of populations were more than 60 yrs. in 2006 (5 which indicate our population is aging, though accurate number of those people in work is lacking. Older adults have physical and mental changes as a common result of aging. Physical changes show itself as decline in physical capabilities, and mental changes involved in sensation and perception, cognition, and motor control (6. So, it is essential to acknowledge these changes and adopt suitable strategies and accommodations for job circumstances and living environments when considering older adults.     In general, a few ergonomics studies explored the effect of aging on environmental modifications and job adaptation. To best of my knowledge, also in Iran there are few studies that presented in conferences or published in journals. Therefore, as a closing remark, it is widely needed to pay more

  19. Exact approaches for scaffolding

    OpenAIRE

    Weller, Mathias; Chateau, Annie; Giroudeau, Rodolphe

    2015-01-01

    This paper presents new structural and algorithmic results around the scaffolding problem, which occurs prominently in next generation sequencing. The problem can be formalized as an optimization problem on a special graph, the "scaffold graph". We prove that the problem is polynomial if this graph is a tree by providing a dynamic programming algorithm for this case. This algorithm serves as a basis to deduce an exact algorithm for general graphs using a tree decomposition of the input. We ex...

  20. 9 CFR 417.6 - Inadequate HACCP Systems.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Inadequate HACCP Systems. 417.6 Section 417.6 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE... ANALYSIS AND CRITICAL CONTROL POINT (HACCP) SYSTEMS § 417.6 Inadequate HACCP Systems. A HACCP system may be...

  1. Boron containing poly-(lactide-co-glycolide) (PLGA) scaffolds for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Doğan, Ayşegül; Demirci, Selami [Department of Genetics and Bioengineering, Faculty of Engineering and Architecture, Yeditepe University 34755 Istanbul (Turkey); Bayir, Yasin [Department of Biochemistry, Faculty of Pharmacy, Ataturk University, 25240, Erzurum (Turkey); Halici, Zekai [Department of Pharmacology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Karakus, Emre [Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Ataturk University, 25240, Erzurum (Turkey); Aydin, Ali [Department of Orthopedics and Traumatology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Cadirci, Elif [Department of Pharmacology, Faculty of Pharmacy, Ataturk University, 25240, Erzurum (Turkey); Albayrak, Abdulmecit [Department of Pharmacology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Demirci, Elif [Department of Pathology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Karaman, Adem [Department of Radiology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Ayan, Arif Kursat [Department of Nuclear Medicine, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Gundogdu, Cemal [Department of Pathology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Şahin, Fikrettin, E-mail: fsahin@yeditepe.edu.tr [Department of Genetics and Bioengineering, Faculty of Engineering and Architecture, Yeditepe University 34755 Istanbul (Turkey)

    2014-11-01

    Scaffold-based bone defect reconstructions still face many challenges due to their inadequate osteoinductive and osteoconductive properties. Various biocompatible and biodegradable scaffolds, combined with proper cell type and biochemical signal molecules, have attracted significant interest in hard tissue engineering approaches. In the present study, we have evaluated the effects of boron incorporation into poly-(lactide-co-glycolide-acid) (PLGA) scaffolds, with or without rat adipose-derived stem cells (rADSCs), on bone healing in vitro and in vivo. The results revealed that boron containing scaffolds increased in vitro proliferation, attachment and calcium mineralization of rADSCs. In addition, boron containing scaffold application resulted in increased bone regeneration by enhancing osteocalcin, VEGF and collagen type I protein levels in a femur defect model. Bone mineralization density (BMD) and computed tomography (CT) analysis proved that boron incorporated scaffold administration increased the healing rate of bone defects. Transplanting stem cells into boron containing scaffolds was found to further improve bone-related outcomes compared to control groups. Additional studies are highly warranted for the investigation of the mechanical properties of these scaffolds in order to address their potential use in clinics. The study proposes that boron serves as a promising innovative approach in manufacturing scaffold systems for functional bone tissue engineering. - Highlights: • Boron containing PLGA scaffolds were developed for bone tissue engineering. • Boron incorporation increased cell viability and mineralization of stem cells. • Boron containing scaffolds increased bone-related protein expression in vivo. • Implantation of stem cells on boron containing scaffolds improved bone healing.

  2. Boron containing poly-(lactide-co-glycolide) (PLGA) scaffolds for bone tissue engineering

    International Nuclear Information System (INIS)

    Doğan, Ayşegül; Demirci, Selami; Bayir, Yasin; Halici, Zekai; Karakus, Emre; Aydin, Ali; Cadirci, Elif; Albayrak, Abdulmecit; Demirci, Elif; Karaman, Adem; Ayan, Arif Kursat; Gundogdu, Cemal; Şahin, Fikrettin

    2014-01-01

    Scaffold-based bone defect reconstructions still face many challenges due to their inadequate osteoinductive and osteoconductive properties. Various biocompatible and biodegradable scaffolds, combined with proper cell type and biochemical signal molecules, have attracted significant interest in hard tissue engineering approaches. In the present study, we have evaluated the effects of boron incorporation into poly-(lactide-co-glycolide-acid) (PLGA) scaffolds, with or without rat adipose-derived stem cells (rADSCs), on bone healing in vitro and in vivo. The results revealed that boron containing scaffolds increased in vitro proliferation, attachment and calcium mineralization of rADSCs. In addition, boron containing scaffold application resulted in increased bone regeneration by enhancing osteocalcin, VEGF and collagen type I protein levels in a femur defect model. Bone mineralization density (BMD) and computed tomography (CT) analysis proved that boron incorporated scaffold administration increased the healing rate of bone defects. Transplanting stem cells into boron containing scaffolds was found to further improve bone-related outcomes compared to control groups. Additional studies are highly warranted for the investigation of the mechanical properties of these scaffolds in order to address their potential use in clinics. The study proposes that boron serves as a promising innovative approach in manufacturing scaffold systems for functional bone tissue engineering. - Highlights: • Boron containing PLGA scaffolds were developed for bone tissue engineering. • Boron incorporation increased cell viability and mineralization of stem cells. • Boron containing scaffolds increased bone-related protein expression in vivo. • Implantation of stem cells on boron containing scaffolds improved bone healing

  3. The Link Between Inadequate Sleep and Obesity in Young Adults.

    Science.gov (United States)

    Vargas, Perla A

    2016-03-01

    The prevalence of obesity has increased dramatically over the past decade. Although an imbalance between caloric intake and physical activity is considered a key factor responsible for the increase, there is emerging evidence suggesting that other factors may be important contributors to weight gain, including inadequate sleep. Overall research evidence suggests that inadequate sleep is associated with obesity. Importantly, the strength and trajectory of the association seem to be influenced by multiple factors including age. Although limited, the emerging evidence suggests young adults might be at the center of a "perfect health storm," exposing them to the highest risk for obesity and inadequate sleep. Unfortunately, the methods necessary for elucidating the complex relationship between sleep and obesity are lacking. Uncovering the underlying factors and trajectories between inadequate sleep and weight gain in different populations may help to identify the windows of susceptibility and to design targeted interventions to prevent the negative impact of obesity and related diseases.

  4. Bone tissue engineering scaffolding: computer-aided scaffolding techniques.

    Science.gov (United States)

    Thavornyutikarn, Boonlom; Chantarapanich, Nattapon; Sitthiseripratip, Kriskrai; Thouas, George A; Chen, Qizhi

    Tissue engineering is essentially a technique for imitating nature. Natural tissues consist of three components: cells, signalling systems (e.g. growth factors) and extracellular matrix (ECM). The ECM forms a scaffold for its cells. Hence, the engineered tissue construct is an artificial scaffold populated with living cells and signalling molecules. A huge effort has been invested in bone tissue engineering, in which a highly porous scaffold plays a critical role in guiding bone and vascular tissue growth and regeneration in three dimensions. In the last two decades, numerous scaffolding techniques have been developed to fabricate highly interconnective, porous scaffolds for bone tissue engineering applications. This review provides an update on the progress of foaming technology of biomaterials, with a special attention being focused on computer-aided manufacturing (Andrade et al. 2002) techniques. This article starts with a brief introduction of tissue engineering (Bone tissue engineering and scaffolds) and scaffolding materials (Biomaterials used in bone tissue engineering). After a brief reviews on conventional scaffolding techniques (Conventional scaffolding techniques), a number of CAM techniques are reviewed in great detail. For each technique, the structure and mechanical integrity of fabricated scaffolds are discussed in detail. Finally, the advantaged and disadvantage of these techniques are compared (Comparison of scaffolding techniques) and summarised (Summary).

  5. Parallel fabrication of macroporous scaffolds.

    Science.gov (United States)

    Dobos, Andrew; Grandhi, Taraka Sai Pavan; Godeshala, Sudhakar; Meldrum, Deirdre R; Rege, Kaushal

    2018-07-01

    Scaffolds generated from naturally occurring and synthetic polymers have been investigated in several applications because of their biocompatibility and tunable chemo-mechanical properties. Existing methods for generation of 3D polymeric scaffolds typically cannot be parallelized, suffer from low throughputs, and do not allow for quick and easy removal of the fragile structures that are formed. Current molds used in hydrogel and scaffold fabrication using solvent casting and porogen leaching are often single-use and do not facilitate 3D scaffold formation in parallel. Here, we describe a simple device and related approaches for the parallel fabrication of macroporous scaffolds. This approach was employed for the generation of macroporous and non-macroporous materials in parallel, in higher throughput and allowed for easy retrieval of these 3D scaffolds once formed. In addition, macroporous scaffolds with interconnected as well as non-interconnected pores were generated, and the versatility of this approach was employed for the generation of 3D scaffolds from diverse materials including an aminoglycoside-derived cationic hydrogel ("Amikagel"), poly(lactic-co-glycolic acid) or PLGA, and collagen. Macroporous scaffolds generated using the device were investigated for plasmid DNA binding and cell loading, indicating the use of this approach for developing materials for different applications in biotechnology. Our results demonstrate that the device-based approach is a simple technology for generating scaffolds in parallel, which can enhance the toolbox of current fabrication techniques. © 2018 Wiley Periodicals, Inc.

  6. Wind energy: Overcoming inadequate wind and modeling uncertainties

    Energy Technology Data Exchange (ETDEWEB)

    Kane, Vivek

    2010-09-15

    'Green Energy' is the call of the day, and significance of Wind Energy can never be overemphasized. But the key question here is - What if the wind resources are inadequate? Studies reveal that the probability of finding favorable wind at a given place on land is only 15%. Moreover, there are inherent uncertainties associated with wind business. Can we overcome inadequate wind resources? Can we scientifically quantify uncertainty and model it to make business sense? This paper proposes a solution, by way of break-through Wind Technologies, combined with advanced tools for Financial Modeling, enabling vital business decisions.

  7. Inadequate cerebral oxygen delivery and central fatigue during strenuous exercise

    DEFF Research Database (Denmark)

    Nybo, Lars; Rasmussen, Peter

    2007-01-01

    Under resting conditions, the brain is protected against hypoxia because cerebral blood flow increases when the arterial oxygen tension becomes low. However, during strenuous exercise, hyperventilation lowers the arterial carbon dioxide tension and blunts the increase in cerebral blood flow, which...... can lead to an inadequate oxygen delivery to the brain and contribute to the development of fatigue....

  8. Clinical significance of inadequate endometrial biopsies prior to hysterectomy.

    Science.gov (United States)

    Turney, Emily H; Farghaly, Hanan; Eskew, Ashley M; Parker, Lynn P; Milam, Michael R

    2012-01-01

    To evaluate preoperative clinical risk factors associated with significant uterine histopathologic abnormalities in final hysterectomy specimens in patients with inadequate preoperative endometrial biopsies. This is an institutional review board-approved, retrospective cohort analysis of 469 consecutive patients who underwent preoperative endometrial biopsies with subsequent hysterectomy from January 1, 2005, to December 31, 2009, at the University of Louisville Medical Center. We analyzed risk factors for inadequate biopsy and for final diagnosis of endometrial pathology (defined as endometrial hyperplasia or uterine cancer). Of the 469 preoperative endometrial biopsies reviewed, 26.2% (123/469) were inadequate (IBx) and 73.8% (346/469) were adequate and benign. IBx on endometrial biopsies was associated with a greater risk of having significant uterine histopathologic abnormalities on final hysterectomy specimens (6.5% vs. 2.3%, RR 2.8 [95% CI 1.1-7.3], p = 0.04). Although inadequate endometrial biopsies are a common finding, they can be associated with significant uterine histopathologic abnormalities on final hysterectomy specimens.

  9. Inadequate pre-season preparation of schoolboy rugby players - a ...

    African Journals Online (AJOL)

    ... in prospective studies at the same schools. The players' knowledge of techniques known to prevent rugby injuries was inadequate and too little attention was paid at the start of the rugby season to training and coaching techniques to reduce injury risk. Coaching errors may therefore have predisposed players to injury.

  10. Determinants of inadequate fruit and vegetable consumption amongst Portuguese adults.

    Science.gov (United States)

    Oliveira, A; Maia, B; Lopes, C

    2014-04-01

    A low consumption of fruit and vegetables (F&V) represents a high burden on health. The present study evaluates sociodemographic, lifestyle and anthropometric determinants of an inadequate consumption of F&V (Diet was assessed by a validated food frequency questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by logistic regression, after sex stratification and controlling for age, education, marital status, smoking, regular physical exercise and total energy intake. Older women and men had 37% and 67%, respectively, lower odds of inadequate F&V consumption (≥65 versus 12 versus excessive alcohol (women: ≥15 g day(-1) ; men: ≥30 g day(-1) ) presented a two- and four-fold higher probability of having inadequate F&V consumption compared to nondrinkers (OR = 1.95, 95% CI = 1.38-2.77 in women; OR = 4.40, 95% CI = 2.70-7.18 in men). In both sexes, an inadequate consumption of F&V was more frequently found in younger, less educated and less physically active subjects with smoking and drinking habits. Strategies aiming to increase F&V consumption should consider these target groups that present a clustering of unhealthy lifestyles. © 2013 The British Dietetic Association Ltd.

  11. Inadequate exercise as a risk factor for sepsis mortality.

    Science.gov (United States)

    Williams, Paul T

    2013-01-01

    Test whether inadequate exercise is related to sepsis mortality. Mortality surveillance of an epidemiological cohort of 155,484 National Walkers' and Runners' Health Study participants residing in the United States. Deaths were monitored for an average of 11.6-years using the National Death index through December 31, 2008. Cox proportional hazard analyses were used to compare sepsis mortality (ICD-10 A40-41) to inadequate exercise (<1.07 METh/d run or walked) as measured on their baseline questionnaires. Deaths occurring within one year of the baseline survey were excluded. Sepsis was the underlying cause in 54 deaths (sepsis(underlying)) and a contributing cause in 184 deaths (sepsis(contributing)), or 238 total sepsis-related deaths (sepsis(total)). Inadequate exercise was associated with 2.24-fold increased risk for sepsis(underlying) (95%CI: 1.21 to 4.07-fold, P = 0.01), 2.11-fold increased risk for sepsis(contributing) (95%CI: 1.51- to 2.92-fold, P<10(-4)), and 2.13-fold increased risk for sepsis(total) (95%CI: 1.59- to 2.84-fold, P<10(-6)) when adjusted for age, sex, race, and cohort. The risk increase did not differ significantly between runners and walkers, by sex, or by age. Sepsis(total) risk was greater in diabetics (P = 10(-5)), cancer survivors (P = 0.0001), and heart attack survivors (P = 0.003) and increased with waist circumference (P = 0.0004). The sepsis(total) risk associated with inadequate exercise persisted when further adjusted for diabetes, prior cancer, prior heart attack and waist circumference, and when excluding deaths with cancer, or cardiovascular, respiratory, or genitourinary disease as the underlying cause. Inadequate exercise also increased sepsis(total) risk in 2163 baseline diabetics (4.78-fold, 95%CI: 2.1- to 13.8-fold, P = 0.0001) when adjusted, which was significantly greater (P = 0.03) than the adjusted risk increase in non-diabetics (1.80-fold, 95%CI: 1.30- to 2.46-fold, P = 0

  12. Augmentation of Rotator Cuff Repair With Soft Tissue Scaffolds

    Science.gov (United States)

    Thangarajah, Tanujan; Pendegrass, Catherine J.; Shahbazi, Shirin; Lambert, Simon; Alexander, Susan; Blunn, Gordon W.

    2015-01-01

    Background Tears of the rotator cuff are one of the most common tendon disorders. Treatment often includes surgical repair, but the rate of failure to gain or maintain healing has been reported to be as high as 94%. This has been substantially attributed to the inadequate capacity of tendon to heal once damaged, particularly to bone at the enthesis. A number of strategies have been developed to improve tendon-bone healing, tendon-tendon healing, and tendon regeneration. Scaffolds have received considerable attention for replacement, reconstruction, or reinforcement of tendon defects but may not possess situation-specific or durable mechanical and biological characteristics. Purpose To provide an overview of the biology of tendon-bone healing and the current scaffolds used to augment rotator cuff repairs. Study Design Systematic review; Level of evidence, 4. Methods A preliminary literature search of MEDLINE and Embase databases was performed using the terms rotator cuff scaffolds, rotator cuff augmentation, allografts for rotator cuff repair, xenografts for rotator cuff repair, and synthetic grafts for rotator cuff repair. Results The search identified 438 unique articles. Of these, 214 articles were irrelevant to the topic and were therefore excluded. This left a total of 224 studies that were suitable for analysis. Conclusion A number of novel biomaterials have been developed into biologically and mechanically favorable scaffolds. Few clinical trials have examined their effect on tendon-bone healing in well-designed, long-term follow-up studies with appropriate control groups. While there is still considerable work to be done before scaffolds are introduced into routine clinical practice, there does appear to be a clear indication for their use as an interpositional graft for large and massive retracted rotator cuff tears and when repairing a poor-quality degenerative tendon. PMID:26665095

  13. Using Scaffolds in Problem-Based Hypermedia

    Science.gov (United States)

    Su, Yuyan; Klein, James D.

    2010-01-01

    This study investigated the use of scaffolds in problem-based hypermedia. Three hundred and twelve undergraduate students enrolled in a computer literacy course worked in project teams to use a hypermedia PBL program focused on designing a personal computer. The PBL program included content scaffolds, metacognitive scaffolds, or no scaffolds.…

  14. Crosslinked pullulan/cellulose acetate fibrous scaffolds for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Atila, Deniz [Department of Engineering Sciences, Middle East Technical University (Turkey); Keskin, Dilek [Department of Engineering Sciences, Middle East Technical University (Turkey); Biomaterials and Tissue Engineering Center of Excellence, Middle East Technical University (Turkey); Tezcaner, Ayşen, E-mail: tezcaner@metu.edu.tr [Department of Engineering Sciences, Middle East Technical University (Turkey); Biomaterials and Tissue Engineering Center of Excellence, Middle East Technical University (Turkey)

    2016-12-01

    Natural polymer based fibrous scaffolds have been explored for bone tissue engineering applications; however, their inadequate 3-dimensionality and poor mechanical properties are among the concerns for their use as bone substitutes. In this study, pullulan (P) and cellulose acetate (CA), two polysaccharides, were electrospun at various P/CA ratios (P{sub 80}/CA{sub 20}, P{sub 50}/CA{sub 50}, and P{sub 20}/CA{sub 80}%) to develop 3D fibrous network. The scaffolds were then crosslinked with trisodium trimetaphosphate (STMP) to improve the mechanical properties and to delay fast weight loss. The lowest weight loss was observed for the groups that were crosslinked with P/STMP 2/1 for 10 min. Fiber morphologies of P{sub 50}/CA{sub 50} were more uniform without phase separation and this group was crosslinked most efficiently among groups. It was found that mechanical properties of P{sub 20}/CA{sub 80} and P{sub 50}/CA{sub 50} were higher than that of P{sub 80}/CA{sub 20.} After crosslinking strain values of P{sub 50}/CA{sub 50} scaffolds were improved and these scaffolds became more stable. Unlike P{sub 80}/CA{sub 20,} uncrosslinked P{sub 50}/CA{sub 50} and P{sub 20}/CA{sub 80} were not lost in PBS. Among all groups, crosslinked P{sub 50}/CA{sub 50} scaffolds had more uniform pores; therefore this group was used for bioactivity and cell culture studies. Apatite-like structures were observed on fibers after SBF incubation. Human Osteogenic Sarcoma Cell Line (Saos-2) seeded onto crosslinked P{sub 50}/CA{sub 50} scaffolds adhered and proliferated. The functionality of cells was tested by measuring ALP activity of the cells and the results indicated their osteoblastic differentiation. In vitro tests showed that scaffolds were cytocompatible. To sum up, crosslinked P{sub 50}/CA{sub 50} scaffolds were proposed as candidate cell carriers for bone tissue engineering applications. - Highlights: • Crosslinked 3D electrospun P/CA scaffolds were prepared for the first time. • CA

  15. Internet addiction: reappraisal of an increasingly inadequate concept.

    Science.gov (United States)

    Starcevic, Vladan; Aboujaoude, Elias

    2017-02-01

    This article re-examines the popular concept of Internet addiction, discusses the key problems associated with it, and proposes possible alternatives. The concept of Internet addiction is inadequate for several reasons. Addiction may be a correct designation only for the minority of individuals who meet the general criteria for addiction, and it needs to be better demarcated from various patterns of excessive or abnormal use. Addiction to the Internet as a medium does not exist, although the Internet as a medium may play an important role in making some behaviors addictive. The Internet can no longer be separated from other potentially overused media, such as text messaging and gaming platforms. Internet addiction is conceptually too heterogeneous because it pertains to a variety of very different behaviors. Internet addiction should be replaced by terms that refer to the specific behaviors (eg, gaming, gambling, or sexual activity), regardless of whether these are performed online or offline.

  16. Inadequate Response to Therapy as a Predictor of Suicide.

    Science.gov (United States)

    Dahlsgaard, Katherine K.; Beck, Aaron T.; Brown, Gregory K.

    1998-01-01

    The role of response to cognitive therapy as a predictor of suicide was investigated by comparing 17 outpatients with mood disorders who committed suicide with 17 matched patients who did not commit suicide. Significant differences were found on several variables including higher levels of hopelessness at termination of therapy. (Author/EMK)

  17. Scaffolding in Assisted Instruction

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available On-The-Job Training, developed as direct instruction, is one of the earliest forms of training. This method is still widely in use today because it requires only a person who knows how to do the task, and the tools the person uses to do the task. This paper is intended to be a study of the methods used in education in Knowledge Society, with more specific aspects in training the trainers; as a result of this approach, it promotes scaffolding in assisted instruction as a reflection of the digital age for the learning process. Training the trainers in old environment with default techniques and designing the learning process in assisted instruction, as an application of the Vygotskian concept of the zone of proximal development (ZPD to the area of computer literacy for the younger users, generate diversity in educational communities and requires standards for technology infrastructure, standards for the content, developed as a concepts map, and applications for personalized in-struction, based on ZPD theory.

  18. Neuronal Networks on Nanocellulose Scaffolds.

    Science.gov (United States)

    Jonsson, Malin; Brackmann, Christian; Puchades, Maja; Brattås, Karoline; Ewing, Andrew; Gatenholm, Paul; Enejder, Annika

    2015-11-01

    Proliferation, integration, and neurite extension of PC12 cells, a widely used culture model for cholinergic neurons, were studied in nanocellulose scaffolds biosynthesized by Gluconacetobacter xylinus to allow a three-dimensional (3D) extension of neurites better mimicking neuronal networks in tissue. The interaction with control scaffolds was compared with cationized nanocellulose (trimethyl ammonium betahydroxy propyl [TMAHP] cellulose) to investigate the impact of surface charges on the cell interaction mechanisms. Furthermore, coatings with extracellular matrix proteins (collagen, fibronectin, and laminin) were investigated to determine the importance of integrin-mediated cell attachment. Cell proliferation was evaluated by a cellular proliferation assay, while cell integration and neurite propagation were studied by simultaneous label-free Coherent anti-Stokes Raman Scattering and second harmonic generation microscopy, providing 3D images of PC12 cells and arrangement of nanocellulose fibrils, respectively. Cell attachment and proliferation were enhanced by TMAHP modification, but not by protein coating. Protein coating instead promoted active interaction between the cells and the scaffold, hence lateral cell migration and integration. Irrespective of surface modification, deepest cell integration measured was one to two cell layers, whereas neurites have a capacity to integrate deeper than the cell bodies in the scaffold due to their fine dimensions and amoeba-like migration pattern. Neurites with lengths of >50 μm were observed, successfully connecting individual cells and cell clusters. In conclusion, TMAHP-modified nanocellulose scaffolds promote initial cellular scaffold adhesion, which combined with additional cell-scaffold treatments enables further formation of 3D neuronal networks.

  19. Initial treatment of severe malaria in children is inadequate – a study ...

    African Journals Online (AJOL)

    -medicated at home. Initial consultations are at primary local health facilities where less effective drugs are prescribed at inadequate dosages. Recommended ACTs were also often prescribed at inadequate dosages. Education in the use of ...

  20. Post-implementation review of inadequate core cooling instrumentation

    International Nuclear Information System (INIS)

    Anderson, J.L.; Anderson, R.L.; Hagen, E.W.; Morelock, T.C.; Huang, T.L.; Phillips, L.E.

    1988-01-01

    Studies of Three Mile Island (TMI) accident identified the need for additional instrumentation to detect inadequate core cooling (ICC) in nuclear power plants. Industry studies by plant owners and reactor vendors supported the conclusion that improvements were needed to help operators diagnose the approach to or existence of ICC and to provide more complete information for operator control of safety injection, flow to minimize the consequences of such an accident. In 1980, the US Nuclear Regulatory Commission (NRC) required further studies by the industry and described ICC instrumentation design requirements that included human factors and environmental considerations. On December 10, 1982, NRC issued to Babcock and Wilcox (BandW) licensees' orders for Modification of License and transmitted to all pressurized water reactor (PWR) licensees Generic Letter 82-28 to inform them of the revised NRC requirements. The instrumentation requirements for detection of ICC include upgraded subcooling margin monitors (SMMs), upgraded core exit thermocouples (CETs), and installation of a reactor coolant inventory tracking system (RCITS)

  1. Mechanical anisotropy of titanium scaffolds

    Directory of Open Access Journals (Sweden)

    Rüegg Jasmine

    2017-09-01

    Full Text Available The clinical performance of an implant, e.g. for the treatment of large bone defects, depends on the implant material, anchorage, surface topography and chemistry, but also on the mechanical properties, like the stiffness. The latter can be adapted by the porosity. Whereas foams show isotropic mechanical properties, digitally modelled scaffolds can be designed with anisotropic behaviour. In this study, we designed and produced 3D scaffolds based on an orthogonal architecture and studied its angle-dependent stiffness. The aim was to produce scaffolds with different orientations of the microarchitecture by selective laser melting and compare the angle-specific mechanical behaviour with an in-silico simulation. The anisotropic characteristics of open-porous implants and technical limitations of the production process were studied.

  2. A scaffold easy to decontaminate

    International Nuclear Information System (INIS)

    Mourek, D.

    1992-01-01

    The conventional scaffold used in the assembling work and in revisions of technological facilities at nuclear power plants has many drawbacks. The most serious of them are a high amount of radioactive waste arising from the decontamination (planing) of the floor timber and from the discarding of damaged irreparable parts, and a considerable corrosion of the carbon steel supporting structure after the decontamination. A detailed description is given of a novel scaffold assembly which can be decontaminated and which exhibits many assets, in particular a good mechanical resistance (also to bad weather), a lower weight, and the use of prepreg floor girders for the construction of service platforms or scaffold bridges which can readily be assembled from the pressed pieces in a modular way. (Z.S.). 4 figs., 4 refs

  3. SUPPORTING LEARNING THROUGH EPISTEMIC SCAFFOLDS EMBEDDED IN A HIGHLIGHTER TOOL

    Directory of Open Access Journals (Sweden)

    Jan Erik Dahl

    2016-11-01

    Full Text Available This article explores the use of epistemic scaffolds embedded in a digital highlighter tool that was used to support students’ readings and discussions of research articles. The use of annotation technologies in education is increasing, and annotations can play a wide variety of epistemic roles; e.g., they can facilitate a deeper level of engagement, support critical thinking, develop cognitive and metacognitive skills and introduce practices that can support knowledge building and independent learning. However, research has shown that the actual tool use often deviates from the underlying knowledge model in the tools. Hence, the situated and mediated nature of these tools is still poorly understood. Research also tends to study the tools as a passed on resource rather than being co-constructed between students and teachers. The researcher argues that approaching these resources as co-constructed can be more productive and can create new spaces for teacher–student dialogues, students’ agency and self-scaffolding.

  4. Systematic Prediction of Scaffold Proteins Reveals New Design Principles in Scaffold-Mediated Signal Transduction

    Science.gov (United States)

    Hu, Jianfei; Neiswinger, Johnathan; Zhang, Jin; Zhu, Heng; Qian, Jiang

    2015-01-01

    Scaffold proteins play a crucial role in facilitating signal transduction in eukaryotes by bringing together multiple signaling components. In this study, we performed a systematic analysis of scaffold proteins in signal transduction by integrating protein-protein interaction and kinase-substrate relationship networks. We predicted 212 scaffold proteins that are involved in 605 distinct signaling pathways. The computational prediction was validated using a protein microarray-based approach. The predicted scaffold proteins showed several interesting characteristics, as we expected from the functionality of scaffold proteins. We found that the scaffold proteins are likely to interact with each other, which is consistent with previous finding that scaffold proteins tend to form homodimers and heterodimers. Interestingly, a single scaffold protein can be involved in multiple signaling pathways by interacting with other scaffold protein partners. Furthermore, we propose two possible regulatory mechanisms by which the activity of scaffold proteins is coordinated with their associated pathways through phosphorylation process. PMID:26393507

  5. IE Information Notice No. 85-75: Improperly installed instrumentation, inadequate quality control and inadequate postmodification testing

    International Nuclear Information System (INIS)

    Jordan, E.L.

    1992-01-01

    On June 10, 1985, the licensee informed the NRC Resident Inspector that for approximately 5 days LaSalle Unit 2 had been without the capability of automatic actuation of emergency core cooling (ECCS) and that for approximately 3 days during this period the plant had been without secondary containment integrity. The major cause of this condition was improper installation (the variable and reference legs were reversed) of the two reactor vessel level actuation switches which control Division 1 automatic depressurization system (ADS), low pressure core spray (LPCS), and reactor core isolation cooling (RCIC). On July 20, 1985, the Trojan Nuclear Power Plant tripped from 100% power because of a turbine trip that was caused by the loss of the unit auxiliary transformer. All systems functioned normally except that low suction pressure caused one auxiliary feedwater pump to trip and then the other auxiliary feedwater pump to trip after restart of the first auxiliary feedwater pump. The cause of the trips of the auxiliary feedwater pumps can be traced back to improper postmodification adjustment and inadequate postmodification testing following retrofit of environmentally qualified controllers for the auxiliary feedwater system. The auxiliary feedwater pump trips on low suction pressure were caused by excessive combined flow from the two auxiliary feedwater pumps that draw from a single header from the condensate storage tank. The flow control valves were open farther than required after new environmentally qualified controllers had been installed during a recent refueling outage

  6. Metabolic regulation during sport events: factual interpretations and inadequate allegations

    Directory of Open Access Journals (Sweden)

    Jacques Remy Poortmans

    2013-09-01

    Full Text Available Different fuels are available to generate ATP for muscle activities during sport events. Glycogen from striated muscles and liver stores may be converted to lactic acid or almost completely oxidized to carbon dioxide (CO2, triacylglycerol within the muscle itself and fatty acids from adipose tissue could be converted to CO2 in acting muscles, some free amino acids can be released within the muscle itself and from intestinal stores to sustain the amount of ATP generation indispensable for muscle contraction. All single biochemical reactions, but one, need one or several enzymes to activate the conversion of a substrate into a product. The energy transformation in biochemical reactions is led by application of so-called free energy. Reversible and non-reversible reactions within a metabolic pathway are dependent on specific enzymes near or far from equilibrium. Allosteric enzymes are regulatory enzymes that provide the direction in the pathway. A regulatory enzyme is either activated or inhibited by small regulators (ligands. A reversible substrate cycle between A and B is catalyzed by two enzymes with different fluxes. The need of ATP production for muscle contraction is under the leadership of regulatory enzymes and available substrate stores. The improvement of adapted metabolic reactions under sport training depends on the appropriate increase of regulatory enzymes within the glycolytic and oxidative pathways. The amount of some specific enzymes is increased by training in order to improve the maximum activity of the metabolic pathway. Unfortunately, several publications do not precisely implicate the appropriate enzyme(s to explain or reject the adaptation induced by the training schedule. A few examples will illustrate the factual interpretation and the inadequate allegation.

  7. A practice scaffolding interactive platform

    DEFF Research Database (Denmark)

    Bundsgaard, Jeppe

    2009-01-01

    A Practice Scaffolding Interactive Platform (PracSIP) is a social learning platform which supports students in collaborative project based learning by simulating a professional practice. A PracSIP puts the core tools of the simulated practice at the students' disposal, it organizes collaboration...

  8. Problem Solving, Scaffolding and Learning

    Science.gov (United States)

    Lin, Shih-Yin

    2012-01-01

    Helping students to construct robust understanding of physics concepts and develop good solving skills is a central goal in many physics classrooms. This thesis examine students' problem solving abilities from different perspectives and explores strategies to scaffold students' learning. In studies involving analogical problem solving…

  9. Chitin Scaffolds in Tissue Engineering

    Science.gov (United States)

    Jayakumar, Rangasamy; Chennazhi, Krishna Prasad; Srinivasan, Sowmya; Nair, Shantikumar V.; Furuike, Tetsuya; Tamura, Hiroshi

    2011-01-01

    Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells either recruited or delivered to an injured site, can eventually regenerate lost or damaged tissue. Most of the researchers working in tissue engineering and regenerative technology attempt to create tissue replacements by culturing cells onto synthetic porous three-dimensional polymeric scaffolds, which is currently regarded as an ideal approach to enhance functional tissue regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation and differentiation. The requirements that must be satisfied by such scaffolds include providing a space with the proper size, shape and porosity for tissue development and permitting cells from the surrounding tissue to migrate into the matrix. Recently, chitin scaffolds have been widely used in tissue engineering due to their non-toxic, biodegradable and biocompatible nature. The advantage of chitin as a tissue engineering biomaterial lies in that it can be easily processed into gel and scaffold forms for a variety of biomedical applications. Moreover, chitin has been shown to enhance some biological activities such as immunological, antibacterial, drug delivery and have been shown to promote better healing at a faster rate and exhibit greater compatibility with humans. This review provides an overview of the current status of tissue engineering/regenerative medicine research using chitin scaffolds for bone, cartilage and wound healing applications. We also outline the key challenges in this field and the most likely directions for future development and we hope that this review will be helpful to the researchers working in the field of tissue engineering and regenerative medicine. PMID:21673928

  10. Parent-child learning interactions: A review of the literature on scaffolding.

    Science.gov (United States)

    Mermelshtine, Roni

    2017-06-01

    Scaffolding can be observed during learning-based interactions, when interventions by parents are adjusted according to children's observed abilities, with the main goal of enabling the child to work independently (Wood et al., 1976, Journal of child psychology and psychiatry, 17, 89). Such contingent instruction behaviours occur from infancy, and are said to be relevant for children's development of executive function, language acquisition, and cognitive and academic abilities. Scaffolding behaviours are considered a product of the family and the wider context, a process affected by parent and child characteristics, and the environment they inhabit. Over 40 years of scaffolding research has produced an abundance of findings. Early investigations were concerned with the conceptualization of scaffolding, whereas more recent studies build upon the theory, testing its correlates and relevance for child development. This article offers an overview of the literature, focusing on the relevance of scaffolding for child developmental outcomes, and the factors associated with individual differences in the process. The article is structured such that the origins of the theory and its definitions are discussed first, followed by an overview of the correlates of scaffolding. The review concludes with a critical evaluation of the literature, proposing novel avenues for future research. © 2017 The British Psychological Society.

  11. Bioactive polymeric scaffolds for tissue engineering

    Directory of Open Access Journals (Sweden)

    Scott Stratton

    2016-12-01

    Full Text Available A variety of engineered scaffolds have been created for tissue engineering using polymers, ceramics and their composites. Biomimicry has been adopted for majority of the three-dimensional (3D scaffold design both in terms of physicochemical properties, as well as bioactivity for superior tissue regeneration. Scaffolds fabricated via salt leaching, particle sintering, hydrogels and lithography have been successful in promoting cell growth in vitro and tissue regeneration in vivo. Scaffold systems derived from decellularization of whole organs or tissues has been popular due to their assured biocompatibility and bioactivity. Traditional scaffold fabrication techniques often failed to create intricate structures with greater resolution, not reproducible and involved multiple steps. The 3D printing technology overcome several limitations of the traditional techniques and made it easier to adopt several thermoplastics and hydrogels to create micro-nanostructured scaffolds and devices for tissue engineering and drug delivery. This review highlights scaffold fabrication methodologies with a focus on optimizing scaffold performance through the matrix pores, bioactivity and degradation rate to enable tissue regeneration. Review highlights few examples of bioactive scaffold mediated nerve, muscle, tendon/ligament and bone regeneration. Regardless of the efforts required for optimization, a shift in 3D scaffold uses from the laboratory into everyday life is expected in the near future as some of the methods discussed in this review become more streamlined.

  12. Alginate based scaffolds for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Valente, J.F.A.; Valente, T.A.M. [CICS-UBI - Centro de Investigacao em Ciencias da Saude, Faculdade de Ciencias da Saude, Universidade da Beira Interior, Covilha (Portugal); Alves, P.; Ferreira, P. [CIEPQPF, Departamento de Engenharia Quimica, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-290 Coimbra (Portugal); Silva, A. [Centro de Ciencia e Tecnologia Aeroespaciais, Universidade da Beira Interior, Covilha (Portugal); Correia, I.J., E-mail: icorreia@ubi.pt [CICS-UBI - Centro de Investigacao em Ciencias da Saude, Faculdade de Ciencias da Saude, Universidade da Beira Interior, Covilha (Portugal)

    2012-12-01

    The design and production of scaffolds for bone tissue regeneration is yet unable to completely reproduce the native bone properties. In the present study new alginate microparticle and microfiber aggregated scaffolds were produced to be applied in this area of regenerative medicine. The scaffolds' mechanical properties were characterized by thermo mechanical assays. Their morphological characteristics were evaluated by isothermal nitrogen adsorption and scanning electron microscopy. The density of both types of scaffolds was determined by helium pycnometry and mercury intrusion porosimetry. Furthermore, scaffolds' cytotoxic profiles were evaluated in vitro by seeding human osteoblast cells in their presence. The results obtained showed that scaffolds have good mechanical and morphological properties compatible with their application as bone substitutes. Moreover, scaffold's biocompatibility was confirmed by the observation of cell adhesion and proliferation after 5 days of being seeded in their presence and by non-radioactive assays. - Highlights: Black-Right-Pointing-Pointer Design and production of scaffolds for bone tissue regeneration. Black-Right-Pointing-Pointer Microparticle and microfiber alginate scaffolds were produced through a particle aggregation technique; Black-Right-Pointing-Pointer Scaffolds' mechanically and biologically properties were characterized through in vitro studies;.

  13. Distributed scaffolding: Wiki collaboration among Latino high school chemistry students

    Science.gov (United States)

    O'Sullivan, Edwin Duncan, Jr.

    The primary purpose of this study was to evaluate if wiki collaboration among Latino high school chemistry students can help reduce the science achievement gap between Latino and White students. The study was a quasi-experimental pre/post control group mixed-methods design. It used three intact sections of a high school chemistry course. The first research question asked if there is a difference in academic achievement between a treatment and control group on selected concepts from the topics of bonding, physical changes, and chemical changes, when Latino high school chemistry students collaborate on a quasi-natural wiki project. Overall results for all three activities (Bonding, Physical Changes, and Chemical Changes) indicated no significant difference between the wiki and control group. However, students performing the chemical changes activity did significantly better than their respective control group. Furthermore, there was a significant association, with large effect size, between group membership and ability to overcome the misconception that aqueous ionic reactants in precipitation reactions exist as molecular pairs of ions. Qualitative analysis of classroom and computer lab dialogue, discussion board communication, student focus groups, teacher interviews, and wiki content attributes the better performance of the chemical changes wiki group to favorable differences in intersubjectivity and calibrated assistance, as well as learning about submicroscopic representations of precipitation reactions in multiple contexts. Furthermore, the nonsignificant result overall points to an aversion to peer editing as a possible cause. Drawing considerably on Vygotsky and Piaget, the results are discussed within the context of how distributed scaffolding facilitated medium levels of cognitive conflict. The second research question asked what the characteristics of distributed metacognitive scaffolding are when Latino high school chemistry students collaborate on a quasi

  14. Antimicrobial Cu-bearing stainless steel scaffolds

    International Nuclear Information System (INIS)

    Wang, Qiang; Ren, Ling; Li, Xiaopeng; Zhang, Shuyuan; Sercombe, Timothy B.; Yang, Ke

    2016-01-01

    Copper-bearing stainless steel scaffolds with two different structures (Body Centered Cubic and Gyroid labyrinth) at two solid fractions (25% and 40%) were fabricated from both 316L powder and a mixture of 316L and elemental Cu powder using selective laser melting, and relative 316L scaffolds were served as control group. After processing, the antimicrobial testing demonstrated that the 316L-Cu scaffolds presented excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus, and the cell viability assay indicated that there was no cytotoxic effect of 316L-Cu scaffolds on rat marrow mesenchymal stem cells. As such, these have the potential to reduce implant-associated infections. The Cu was also found to homogeneously distribute within the microstructure by scanning electronic microcopy. The addition of Cu would not significantly affect its strength and stiffness compared to 316L scaffold, and the stiffness of all the scaffolds (3-20GPa) is similar to that of bone and much less than that of bulk stainless steel. Consequently, fabrication of such low stiffness porous structures, especially coupled with the addition of antimicrobial Cu, may provide a new direction for medical stainless steels. - Highlights: • 316L-Cu scaffolds were fabricated by using selective laser melting (SLM). • 316L-Cu scaffolds showed satisfied antimicrobial activities. • 316L-Cu scaffolds have no cytotoxic effect on normal cells. • Other properties of 316L-Cu scaffolds were similar to 316L scaffolds. • 316L-Cu scaffolds have the potential to be used in orthopedic applications.

  15. Antimicrobial Cu-bearing stainless steel scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qiang, E-mail: mfqwang@163.com [School of Stomatology, China Medical University, Shenyang 110002 (China); Ren, Ling [Institute of Metal Research, Chinese Academy of Sciences (China); Li, Xiaopeng [School of Mechanical and Chemical Engineering, The University of Western Australia (Australia); Zhang, Shuyuan [Institute of Metal Research, Chinese Academy of Sciences (China); Sercombe, Timothy B., E-mail: tim.sercombe@uwa.edu.au [School of Mechanical and Chemical Engineering, The University of Western Australia (Australia); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences (China)

    2016-11-01

    Copper-bearing stainless steel scaffolds with two different structures (Body Centered Cubic and Gyroid labyrinth) at two solid fractions (25% and 40%) were fabricated from both 316L powder and a mixture of 316L and elemental Cu powder using selective laser melting, and relative 316L scaffolds were served as control group. After processing, the antimicrobial testing demonstrated that the 316L-Cu scaffolds presented excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus, and the cell viability assay indicated that there was no cytotoxic effect of 316L-Cu scaffolds on rat marrow mesenchymal stem cells. As such, these have the potential to reduce implant-associated infections. The Cu was also found to homogeneously distribute within the microstructure by scanning electronic microcopy. The addition of Cu would not significantly affect its strength and stiffness compared to 316L scaffold, and the stiffness of all the scaffolds (3-20GPa) is similar to that of bone and much less than that of bulk stainless steel. Consequently, fabrication of such low stiffness porous structures, especially coupled with the addition of antimicrobial Cu, may provide a new direction for medical stainless steels. - Highlights: • 316L-Cu scaffolds were fabricated by using selective laser melting (SLM). • 316L-Cu scaffolds showed satisfied antimicrobial activities. • 316L-Cu scaffolds have no cytotoxic effect on normal cells. • Other properties of 316L-Cu scaffolds were similar to 316L scaffolds. • 316L-Cu scaffolds have the potential to be used in orthopedic applications.

  16. Cell–scaffold interaction within engineered tissue

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Haiping; Liu, Yuanyuan, E-mail: Yuanyuan_liu@shu.edu.cn; Jiang, Zhenglong; Chen, Weihua; Yu, Yongzhe; Hu, Qingxi

    2014-05-01

    The structure of a tissue engineering scaffold plays an important role in modulating tissue growth. A novel gelatin–chitosan (Gel–Cs) scaffold with a unique structure produced by three-dimensional printing (3DP) technology combining with vacuum freeze-drying has been developed for tissue-engineering applications. The scaffold composed of overall construction, micro-pore, surface morphology, and effective mechanical property. Such a structure meets the essential design criteria of an ideal engineered scaffold. The favorable cell–matrix interaction supports the active biocompatibility of the structure. The structure is capable of supporting cell attachment and proliferation. Cells seeded into this structure tend to maintain phenotypic shape and secreted large amounts of extracellular matrix (ECM) and the cell growth decreased the mechanical properties of scaffold. This novel biodegradable scaffold has potential applications for tissue engineering based upon its unique structure, which acts to support cell growth. - Highlights: • The scaffold is not only for providing a surface for cell residence but also for determining cell phenotype and retaining structural integrity. • The mechanical property of scaffold can be affected by activities of cell. • The scaffold provides a microenvironment for cell attachment, growth, and migration.

  17. Platelet lysate embedded scaffolds for skin regeneration.

    Science.gov (United States)

    Sandri, Giuseppina; Bonferoni, Maria Cristina; Rossi, Silvia; Ferrari, Franca; Mori, Michela; Cervio, Marila; Riva, Federica; Liakos, Ioannis; Athanassiou, Athanassia; Saporito, Francesca; Marini, Lara; Caramella, Carla

    2015-04-01

    The work presents the development of acellular scaffolds extemporaneously embedded with platelet lysate (PL), as an innovative approach in the field of tissue regeneration/reparation. PL embedded scaffolds should have a tridimensional architecture to support cell migration and growth, in order to restore skin integrity. For this reason, chondroitin sulfate (CS) was associated with sodium alginate (SA) to prepare highly porous systems. The developed scaffolds were characterized for chemical stability to γ-radiation, morphology, hydration and mechanical properties. Moreover, the capability of fibroblasts and endothelial cells to populate the scaffold was evaluated by means of proliferation test 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and confocal laser scanning microscopy study. The scaffolds, not altered by sterilization, were characterized by limited swelling and high flexibility, by foam-like structure with bubbles that formed a high surface area and irregular texture suitable for cell adhesion. Cell growth and scaffold population were evident on the bubble surface, where the cells appeared anchored to the scaffold structure. Scaffold network based on CS and SA demonstrated to be an effective support to enhance and to allow fibroblasts and endothelial cells (human umbilical vein endothelial cells, HUVEC) adhesion and proliferation. In particular, it could be hypothesized that cell adhesion was facilitated by the synergic effect of PL and CS. Although further in vivo evaluation is needed, on the basis of in vitro results, PL embedded scaffolds seem promising systems for skin wound healing.

  18. Inadequate humidification of respiratory gases during mechanical ventilation of the newborn.

    Science.gov (United States)

    Tarnow-Mordi, W O; Sutton, P; Wilkinson, A R

    1986-01-01

    Proximal airway humidity was measured during mechanical ventilation in 14 infants using an electronic hygrometer. Values below recommended minimum humidity of adult inspired gas were recorded on 251 of 396 occasions. Inadequate humidification, largely due to inadequate proximal airway temperature, is commoner than recognised in infants receiving mechanical ventilation. PMID:3740912

  19. WiseScaffolder: an algorithm for the semi-automatic scaffolding of Next Generation Sequencing data.

    Science.gov (United States)

    Farrant, Gregory K; Hoebeke, Mark; Partensky, Frédéric; Andres, Gwendoline; Corre, Erwan; Garczarek, Laurence

    2015-09-03

    The sequencing depth provided by high-throughput sequencing technologies has allowed a rise in the number of de novo sequenced genomes that could potentially be closed without further sequencing. However, genome scaffolding and closure require costly human supervision that often results in genomes being published as drafts. A number of automatic scaffolders were recently released, which improved the global quality of genomes published in the last few years. Yet, none of them reach the efficiency of manual scaffolding. Here, we present an innovative semi-automatic scaffolder that additionally helps with chimerae resolution and generates valuable contig maps and outputs for manual improvement of the automatic scaffolding. This software was tested on the newly sequenced marine cyanobacterium Synechococcus sp. WH8103 as well as two reference datasets used in previous studies, Rhodobacter sphaeroides and Homo sapiens chromosome 14 (http://gage.cbcb.umd.edu/). The quality of resulting scaffolds was compared to that of three other stand-alone scaffolders: SSPACE, SOPRA and SCARPA. For all three model organisms, WiseScaffolder produced better results than other scaffolders in terms of contiguity statistics (number of genome fragments, N50, LG50, etc.) and, in the case of WH8103, the reliability of the scaffolds was confirmed by whole genome alignment against a closely related reference genome. We also propose an efficient computer-assisted strategy for manual improvement of the scaffolding, using outputs generated by WiseScaffolder, as well as for genome finishing that in our hands led to the circularization of the WH8103 genome. Altogether, WiseScaffolder proved more efficient than three other scaffolders for both prokaryotic and eukaryotic genomes and is thus likely applicable to most genome projects. The scaffolding pipeline described here should be of particular interest to biologists wishing to take advantage of the high added value of complete genomes.

  20. SHOP: scaffold hopping by GRID-based similarity searches

    DEFF Research Database (Denmark)

    Bergmann, Rikke; Linusson, Anna; Zamora, Ismael

    2007-01-01

    A new GRID-based method for scaffold hopping (SHOP) is presented. In a fully automatic manner, scaffolds were identified in a database based on three types of 3D-descriptors. SHOP's ability to recover scaffolds was assessed and validated by searching a database spiked with fragments of known...... scaffolds were in the 31 top-ranked scaffolds. SHOP also identified new scaffolds with substantially different chemotypes from the queries. Docking analysis indicated that the new scaffolds would have similar binding modes to those of the respective query scaffolds observed in X-ray structures...

  1. Neuromodulation of Behavioral and Cognitive Development across the Life Span

    Science.gov (United States)

    Li, Shu-Chen

    2012-01-01

    Among other mechanisms, behavioral and cognitive development entail, on the one hand, contextual scaffolding and, on the other hand, neuromodulation of adaptive neurocognitive representations across the life span. Key brain networks underlying cognition, emotion, and motivation are innervated by major transmitter systems (e.g., the catecholamines…

  2. Rubric Authoring Tool Supporting Cognitive Skills Assessment across an Institution

    Science.gov (United States)

    Simper, Natalie

    2018-01-01

    This paper explores a method to support instructors in assessing cognitive skills in their course, designed to enable aggregation of data across an institution. A rubric authoring tool, "BASICS" (Building Assessment Scaffolds for Intellectual Cognitive Skills) was built as part of the Queen's University Learning Outcomes Assessment (LOA)…

  3. Cell penetration to nanofibrous scaffolds

    Czech Academy of Sciences Publication Activity Database

    Rampichová, Michala; Buzgo, Matej; Chvojka, J.; Prosecká, Eva; Kofroňová, Olga; Amler, Evžen

    2014-01-01

    Roč. 8, č. 1 (2014), s. 36-41 ISSN 1933-6918 Grant - others:GA UK(CZ) 384311; GA UK(CZ) 626012; GA UK(CZ) 270513; GA UK(CZ) 330611; GA UK(CZ) 648112; GA MZd(CZ) NT12156; GA MŠk(CZ) project IPv6 Institutional support: RVO:68378041 ; RVO:61388971 Keywords : fibrous scaffold * mesenchymal stem cells * Forcespinning (R) Subject RIV: FP - Other Medical Disciplines Impact factor: 4.505, year: 2014

  4. Recombinant protein scaffolds for tissue engineering

    International Nuclear Information System (INIS)

    Werkmeister, Jerome A; Ramshaw, John A M

    2012-01-01

    New biological materials for tissue engineering are now being developed using common genetic engineering capabilities to clone and express a variety of genetic elements that allow cost-effective purification and scaffold fabrication from these recombinant proteins, peptides or from chimeric combinations of these. The field is limitless as long as the gene sequences are known. The utility is dependent on the ease, product yield and adaptability of these protein products to the biomedical field. The development of recombinant proteins as scaffolds, while still an emerging technology with respect to commercial products, is scientifically superior to current use of natural materials or synthetic polymer scaffolds, in terms of designing specific structures with desired degrees of biological complexities and motifs. In the field of tissue engineering, next generation scaffolds will be the key to directing appropriate tissue regeneration. The initial period of biodegradable synthetic scaffolds that provided shape and mechanical integrity, but no biological information, is phasing out. The era of protein scaffolds offers distinct advantages, particularly with the combination of powerful tools of molecular biology. These include, for example, the production of human proteins of uniform quality that are free of infectious agents and the ability to make suitable quantities of proteins that are found in low quantity or are hard to isolate from tissue. For the particular needs of tissue engineering scaffolds, fibrous proteins like collagens, elastin, silks and combinations of these offer further advantages of natural well-defined structural scaffolds as well as endless possibilities of controlling functionality by genetic manipulation. (topical review)

  5. Scaffolding Mathematical Modelling with a Solution Plan

    Science.gov (United States)

    Schukajlow, Stanislaw; Kolter, Jana; Blum, Werner

    2015-01-01

    In the study presented in this paper, we examined the possibility to scaffold mathematical modelling with strategies. The strategies were prompted using an instrument called "solution plan" as a scaffold. The effects of this step by step instrument on mathematical modelling competency and on self-reported strategies were tested using…

  6. Scaffolding proteins: not such innocent bystanders.

    Science.gov (United States)

    Smith, F Donelson; Scott, John D

    2013-06-17

    Sequential transfer of information from one enzyme to the next within the confines of a protein kinase scaffold enhances signal transduction. Though frequently considered to be inert organizational elements, two recent reports implicate kinase-scaffolding proteins as active participants in signal relay. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Scaffolding Proteins: Not Such Innocent Bystanders

    OpenAIRE

    Smith, F. Donelson; Scott, John D.

    2013-01-01

    Sequential transfer of information from one enzyme to the next within the confines of a protein kinase scaffold enhances signal transduction. Though frequently considered to be inert organizational elements, two recent reports implicate kinase-scaffolding proteins as active participants in signal relay.

  8. Metacognitive Scaffolding in an Innovative Learning Arrangement

    Science.gov (United States)

    Molenaar, Inge; van Boxtel, Carla A. M.; Sleegers, Peter J. C.

    2011-01-01

    This study examined the effects of metacognitive scaffolds on learning outcomes of collaborating students in an innovative learning arrangement. The triads were supported by computerized scaffolds, which were dynamically integrated into the learning process and took a structuring or problematizing form. In an experimental design the two…

  9. Teaching language teachers scaffolding professional learning

    CERN Document Server

    Maggioli, Gabriel Diaz

    2012-01-01

    Teaching Language Teachers: Scaffolding Professional Learning provides an updated view of as well as a reader-friendly introduction to the field of Teaching Teachers, with special reference to language teaching. By taking a decidedly Sociocultural perspective, the book addresses the main role of the Teacher of Teachers (ToT) as that of scaffolding the professional learning of aspiring teachers.

  10. Scaffolding across the lifespan in history-dependent decision-making.

    Science.gov (United States)

    Cooper, Jessica A; Worthy, Darrell A; Gorlick, Marissa A; Maddox, W Todd

    2013-06-01

    We examined the relationship between pressure and age-related changes in decision-making using a task for which currently available rewards depend on the participant's previous history of choices. Optimal responding in this task requires the participant to learn how his or her current choices affect changes in the future rewards given for each option. Building on the scaffolding theory of aging and cognition, we predicted that when additional frontal resources are available, compensatory recruitment leads to increased monitoring and increased use of heuristic-based strategies, ultimately leading to better performance. Specifically, we predicted that scaffolding would result in an age-related performance advantage under no pressure conditions. We also predicted that, although younger adults would engage in scaffolding under pressure, older adults would not have additional resources available for increased scaffolding under pressure-packed conditions, leading to an age-related performance deficit. Both predictions were supported by the data. In addition, computational models were used to evaluate decision-making strategies employed by each participant group. As expected, older adults under no pressure conditions and younger adults under pressure conditions showed increased use of heuristic-based strategies relative to older adults under pressure and younger adults under no pressure, respectively. These results are consistent with the notion that scaffolding can occur across the life span in the face of an environmental challenge. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  11. The significance of inadequate transcranial Doppler studies in children with sickle cell disease.

    Directory of Open Access Journals (Sweden)

    Simon Greenwood

    Full Text Available Sickle cell disease (SCD is a common cause of cerebrovascular disease in childhood. Primary stroke prevention is effective using transcranial Doppler (TCD scans to measure intracranial blood velocities, and regular blood transfusions or hydroxycarbamide when these are abnormal. Inadequate TCD scans occur when it is not possible to measure velocities in all the main arteries. We have investigated the prevalence and significance of this in a retrospective audit of 3915 TCD scans in 1191 children, performed between 2008 and 2015. 79% scans were normal, 6.4% conditional, 2.8% abnormal and 12% inadequate. 21.6% of 1191 patients had an inadequate scan at least once. The median age of first inadequate scan was 3.3 years (0.7-19.4, with a U-shaped frequency distribution with age: 28% aged 2-3 years, 3.5% age 10 years, 25% age 16 years. In young children reduced compliance was the main reason for inadequate TCDs, whereas in older children it was due to a poor temporal ultrasound window. The prevalence of inadequate TCD was 8% in the main Vascular Laboratory at King's College Hospital and significantly higher at 16% in the outreach clinics (P<0.0001, probably due to the use of a portable ultrasound machine. Inadequate TCD scans were not associated with underlying cerebrovascular disease.

  12. Behaviorally inadequate

    DEFF Research Database (Denmark)

    Kasperbauer, Tyler Joshua

    2014-01-01

    According to situationism in psychology, behavior is primarily influenced by external situational factors rather than internal traits or motivations such as virtues. Environmental ethicists wish to promote pro-environmental behaviors capable of providing adequate protection for the environment...

  13. Teenaged Internet Tutors' Use of Scaffolding with Older Learners

    Science.gov (United States)

    Tambaum, Tiina

    2017-01-01

    This study analyses how teenaged instructors paired with older learners make use of scaffolding. Video data were categorised according to 15 types of direct scaffolding tactics, indirect scaffolding, and unused scaffolding opportunities. The results show that a teenager who is unprepared for the role of an instructor of Internet skills for older…

  14. Student Use of Scaffolding Software: Relationships with Motivation and Conceptual Understanding

    Science.gov (United States)

    Butler, Kyle A.; Lumpe, Andrew

    2008-10-01

    This study was designed to theoretically articulate and empirically assess the role of computer scaffolds. In this project, several examples of educational software were developed to scaffold the learning of students performing high level cognitive activities. The software used in this study, Artemis, focused on scaffolding the learning of students as they performed information seeking activities. As 5th grade students traveled through a project-based science unit on photosynthesis, researchers used a pre-post design to test for both student motivation and student conceptual understanding of photosynthesis. To measure both variables, a motivation survey and three methods of concept map analysis were used. The student use of the scaffolding features was determined using a database that tracked students' movement between scaffolding tools. The gain scores of each dependent variable was then correlated to the students' feature use (time and hits) embedded in the Artemis Interface. This provided the researchers with significant relationships between the scaffolding features represented in the software and student motivation and conceptual understanding of photosynthesis. There were a total of three significant correlations in comparing the scaffolding use by hits (clicked on) with the dependent variables and only one significant correlation when comparing the scaffold use in time. The first significant correlation ( r = .499, p students' task value. This correlation supports the assumption that there is a positive relationship between the student use of the saving/viewing features and the students' perception of how interesting, how important, and how useful the task is. The second significant correlation ( r = 0.553, p students' self-efficacy for learning and performance. This correlation supports the assumption that there is a positive relationship between the student use of the searching features and the students' perception of their ability to accomplish a task as

  15. Titanate nanotube coatings on biodegradable photopolymer scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Beke, S., E-mail: szabolcs.beke@iit.it [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Kőrösi, L. [Department of Biotechnology, Nanophage Therapy Center, Enviroinvest Corporation, Kertváros u. 2, H-7632, Pécs (Hungary); Scarpellini, A. [Department of Nanochemistry, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Anjum, F.; Brandi, F. [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy)

    2013-05-01

    Rigid, biodegradable photopolymer scaffolds were coated with titanate nanotubes (TNTs) by using a spin-coating method. TNTs were synthesized by a hydrothermal process at 150 °C under 4.7 bar ambient pressure. The biodegradable photopolymer scaffolds were produced by mask-assisted excimer laser photocuring at 308 nm. For scaffold coating, a stable ethanolic TNT sol was prepared by a simple colloid chemical route without the use of any binding compounds or additives. Scanning electron microscopy along with elemental analysis revealed that the scaffolds were homogenously coated by TNTs. The developed TNT coating can further improve the surface geometry of fabricated scaffolds, and therefore it can further increase the cell adhesion. Highlights: ► Biodegradable scaffolds were produced by mask-assisted UV laser photocuring. ► Titanate nanotube deposition was carried out without binding compounds or additives. ► The titanate nanotube coating can further improve the surface geometry of scaffolds. ► These reproducible platforms will be of high importance for biological applications.

  16. Scaffold translation: barriers between concept and clinic.

    Science.gov (United States)

    Hollister, Scott J; Murphy, William L

    2011-12-01

    Translation of scaffold-based bone tissue engineering (BTE) therapies to clinical use remains, bluntly, a failure. This dearth of translated tissue engineering therapies (including scaffolds) remains despite 25 years of research, research funding totaling hundreds of millions of dollars, over 12,000 papers on BTE and over 2000 papers on BTE scaffolds alone in the past 10 years (PubMed search). Enabling scaffold translation requires first an understanding of the challenges, and second, addressing the complete range of these challenges. There are the obvious technical challenges of designing, manufacturing, and functionalizing scaffolds to fill the Form, Fixation, Function, and Formation needs of bone defect repair. However, these technical solutions should be targeted to specific clinical indications (e.g., mandibular defects, spine fusion, long bone defects, etc.). Further, technical solutions should also address business challenges, including the need to obtain regulatory approval, meet specific market needs, and obtain private investment to develop products, again for specific clinical indications. Finally, these business and technical challenges present a much different model than the typical research paradigm, presenting the field with philosophical challenges in terms of publishing and funding priorities that should be addressed as well. In this article, we review in detail the technical, business, and philosophical barriers of translating scaffolds from Concept to Clinic. We argue that envisioning and engineering scaffolds as modular systems with a sliding scale of complexity offers the best path to addressing these translational challenges. © Mary Ann Liebert, Inc.

  17. Inverse Opal Scaffolds and Their Biomedical Applications.

    Science.gov (United States)

    Zhang, Yu Shrike; Zhu, Chunlei; Xia, Younan

    2017-09-01

    Three-dimensional porous scaffolds play a pivotal role in tissue engineering and regenerative medicine by functioning as biomimetic substrates to manipulate cellular behaviors. While many techniques have been developed to fabricate porous scaffolds, most of them rely on stochastic processes that typically result in scaffolds with pores uncontrolled in terms of size, structure, and interconnectivity, greatly limiting their use in tissue regeneration. Inverse opal scaffolds, in contrast, possess uniform pores inheriting from the template comprised of a closely packed lattice of monodispersed microspheres. The key parameters of such scaffolds, including architecture, pore structure, porosity, and interconnectivity, can all be made uniform across the same sample and among different samples. In conjunction with a tight control over pore sizes, inverse opal scaffolds have found widespread use in biomedical applications. In this review, we provide a detailed discussion on this new class of advanced materials. After a brief introduction to their history and fabrication, we highlight the unique advantages of inverse opal scaffolds over their non-uniform counterparts. We then showcase their broad applications in tissue engineering and regenerative medicine, followed by a summary and perspective on future directions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Multilayer scaffolds in orthopaedic tissue engineering.

    Science.gov (United States)

    Atesok, Kivanc; Doral, M Nedim; Karlsson, Jon; Egol, Kenneth A; Jazrawi, Laith M; Coelho, Paulo G; Martinez, Amaury; Matsumoto, Tomoyuki; Owens, Brett D; Ochi, Mitsuo; Hurwitz, Shepard R; Atala, Anthony; Fu, Freddie H; Lu, Helen H; Rodeo, Scott A

    2016-07-01

    The purpose of this study was to summarize the recent developments in the field of tissue engineering as they relate to multilayer scaffold designs in musculoskeletal regeneration. Clinical and basic research studies that highlight the current knowledge and potential future applications of the multilayer scaffolds in orthopaedic tissue engineering were evaluated and the best evidence collected. Studies were divided into three main categories based on tissue types and interfaces for which multilayer scaffolds were used to regenerate: bone, osteochondral junction and tendon-to-bone interfaces. In vitro and in vivo studies indicate that the use of stratified scaffolds composed of multiple layers with distinct compositions for regeneration of distinct tissue types within the same scaffold and anatomic location is feasible. This emerging tissue engineering approach has potential applications in regeneration of bone defects, osteochondral lesions and tendon-to-bone interfaces with successful basic research findings that encourage clinical applications. Present data supporting the advantages of the use of multilayer scaffolds as an emerging strategy in musculoskeletal tissue engineering are promising, however, still limited. Positive impacts of the use of next generation scaffolds in orthopaedic tissue engineering can be expected in terms of decreasing the invasiveness of current grafting techniques used for reconstruction of bone and osteochondral defects, and tendon-to-bone interfaces in near future.

  19. A Study on the Formulation Process of Bruner's Concept of "Scaffolding"

    OpenAIRE

    Imai, Yasuharu

    2008-01-01

    The purpose of this paper is to clarify the Vygotsky's influence on the formulation of Jerome Bruner's "Scaffolding" theory. In section 1, Bruner is encounter with Vygostky's theory was described, and it was pointed out, in section 2, that Bruner's idea of cognitive development changed through Bruner's acquaintance of Vygotsky's disciple Ruria. In section 3, Bruner's evaluation of Vygostky was discussed through the examination into Vygotsky's Thought and Language. And section 4, Bruner's unde...

  20. Scaffolding With and Through Videos

    DEFF Research Database (Denmark)

    Otrel-Cass, Kathrin; Khoo, Elaine; Cowie, Bronwen

    2012-01-01

    In New Zealand and internationally claims are being made about the potential for information and communication technologies (ICTs) to transform teaching and learning. However, the theoretical underpinnings explaining the complex interplay between the content, pedagogy and technology a teacher needs...... to scaffold learning. It showcases the intricate interplay between teachers’ knowledge about content, digital video technology, and students’ learning needs based on a qualitative study of two science teachers and their students in a New Zealand primary school....... to consider must be expanded. This article explicates theoretical and practical ideas related to teachers’ application of their ICT technology, pedagogy, and content knowledge (TPACK) in science. The article unpacks the social and technological dimensions of teachers’ use of TPACK when they use digital videos...

  1. Semiotic Scaffolding in Living Systems

    DEFF Research Database (Denmark)

    Hoffmeyer, Jesper

    2008-01-01

    The apparently purposeful nature of living systems is obtained through a sophisticated network of semiotic controls whereby biochemical, physiological and behavioral processes become tuned to the needs of the system. The operation of these semiotic controls takes place and is enabled across...... a diversity of levels. Such semiotic controls may be distinguished from ordinary deterministic control mechanisms through an inbuilt anticipatory capacity based on a distinct kind of causation that I call here "semiotic causation" to denote the bringing about of changes under the guidance of interpretation...... in a local .context. Anticipation through the skilled interpretation of indicators of temporal relations in the context of a particular survival project (or life strategy) guides organismic behavior towards local ends. This network of semiotic controls establishes an enormously complex semiotic scaffolding...

  2. Computational Exploration of Molecular Scaffolds in Medicinal Chemistry.

    Science.gov (United States)

    Hu, Ye; Stumpfe, Dagmar; Bajorath, Jürgen

    2016-05-12

    The scaffold concept is widely applied in medicinal chemistry. Scaffolds are mostly used to represent core structures of bioactive compounds. Although the scaffold concept has limitations and is often viewed differently from a chemical and computational perspective, it has provided a basis for systematic investigations of molecular cores and building blocks, going far beyond the consideration of individual compound series. Over the past 2 decades, alternative scaffold definitions and organization schemes have been introduced and scaffolds have been studied in a variety of ways and increasingly on a large scale. Major applications of the scaffold concept include the generation of molecular hierarchies, structural classification, association of scaffolds with biological activities, and activity prediction. This contribution discusses computational approaches for scaffold generation and analysis, with emphasis on recent developments impacting medicinal chemistry. A variety of scaffold-based studies are discussed, and a perspective on scaffold methods is provided.

  3. Analog series-based scaffolds: computational design and exploration of a new type of molecular scaffolds for medicinal chemistry

    Science.gov (United States)

    Dimova, Dilyana; Stumpfe, Dagmar; Hu, Ye; Bajorath, Jürgen

    2016-01-01

    Aim: Computational design of and systematic search for a new type of molecular scaffolds termed analog series-based scaffolds. Materials & methods: From currently available bioactive compounds, analog series were systematically extracted, key compounds identified and new scaffolds isolated from them. Results: Using our computational approach, more than 12,000 scaffolds were extracted from bioactive compounds. Conclusion: A new scaffold definition is introduced and a computational methodology developed to systematically identify such scaffolds, yielding a large freely available scaffold knowledge base. PMID:28116132

  4. How many medical requests for US, body CT, and musculoskeletal MR exams in outpatients are inadequate?

    International Nuclear Information System (INIS)

    Sardanelli, Francesco; Aliprandi, Alberto; Fausto, Alfonso

    2005-01-01

    Purpose: Our aim was to evaluate how many medical requests for US, CT and MR outpatients exams are inadequate. Materials and methods: We evaluated three series of consecutive requests for outpatients exams, distinguishing firstly the adequate from the inadequate requests. The inadequate requests were classified as: (A) absence of real indication; (B) lacking or vague clinical query; (C) absence of important information on patient's status. US requests concerned 282 patients for 300 body segments, as follows: neck (n=50); upper abdomen (n=95); lower abdomen (n=12); upper and lower abdomen (n=84); musculoskeletal (n=32); other body segments (n=27). CT requests concerned 280 patients for 300 body segments, as follows: chest (n=67); abdomen (n=77); musculoskeletal (n=94); other body segments (n=62). MR musculoskeletal requests concerned 138 patients for 150 body segments, as follows: knee (n=87); ankle (n=13); shoulder (n=28); other body segments (n=22). Results: A total of 228/300 US requests (76%) were inadequate, ranging from 66% (musculoskeletal) to 86% (neck) classified as: A, 21/228 (9%); B, 130/228 (57%); C, 77/228 (34%). A total of 231/300 (77%) body CT request were inadequate, ranging from 72% (chest) to 86% (musculoskeletal), classified as: A, 22/231 (10%); B, 88/231 (38%); C, 121/231 (52%). A total of 124/150 (83%) MR musculoskeletal requests were inadequate, ranging from 69% (ankle) to 89% (knee), classified as: A, 12/124 (10%); B, 50/124 (40%); C, 62/124 (50%). No significant difference was found among the levels of inadequacy for the three techniques and among the body segments for each of the three techniques. Conclusions: The majority of the medical requests for outpatients exams turned out to be inadequate. A large communication gap between referring physicians and radiologists needs to be filled [it

  5. Prevalence of Inadequate Immunity to Measles, Mumps, Rubella, and Varicella in MLB and NBA Athletes.

    Science.gov (United States)

    Conway, Justin J; Toresdahl, Brett G; Ling, Daphne I; Boniquit, Nicole T; Callahan, Lisa R; Kinderknecht, James J

    2018-05-01

    Multiple outbreaks of vaccine-preventable viral diseases have occurred in professional sports in recent years. Currently, there is no established protocol for vaccination or immunity screening for professional athletes. There are significant differences in the prevalence of inadequate immunity dependent on age, sport, country of birth, and participation in collegiate sports. Cross-sectional cohort study. Level 4. A sample of Major League Baseball (MLB) and National Basketball Association (NBA) players were screened for serologic evidence of immunity to measles, mumps, rubella, and varicella prior to the 2015 and 2016 seasons. The results were designated as adequate (immune) or inadequate (equivocal or nonimmune) based on laboratory criteria. Comparison with an age-matched control group was performed using data from the National Health and Nutrition Examination Survey (NHANES). A total of 98 athletes (62 MLB, 36 NBA) were screened. The prevalence of inadequate immunity for any virus was 35.5% in MLB players and 33.3% in NBA players. There was a significantly greater risk of inadequate immunity to rubella (risk ratio, 6.38; P < 0.01) and varicella (risk ratio, 4.21; P < 0.01) in athletes compared with the age-matched NHANES population. Our analysis did not reveal differences in rates of immunity based on sport, country of birth (US born vs international), or participation in college athletics. There was a lower rate of inadequate immunity to varicella with increasing age (odds ratio, 0.72; P = 0.05). One-third of athletes studied had inadequate immunity to 1 of the 4 viruses tested. Younger players had a significantly greater risk of inadequate immunity to varicella. Birth outside the US and lack of participation in college athletics were not found to influence immunity rates. These results can inform the development of future screening programs to prevent outbreaks of viral infections in professional athletes.

  6. Comprehensive assessment of electrospun scaffolds hemocompatibility

    Czech Academy of Sciences Publication Activity Database

    Horáková, J.; Mikeš, P.; Šaman, A.; Švarcová, T.; Jenčová, V.; Suchý, Tomáš; Heczková, B.; Jakubková, Š.; Jiroušová, J.; Procházková, R.

    2018-01-01

    Roč. 82, JAN 1 (2018), s. 330-335 ISSN 0928-4931 Institutional support: RVO:67985891 Keywords : fibrous scaffolds * blood compatibility * polycaprolactone * copolymer of polylactide and polycaprolactone * collagen Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery

  7. Biomimetic nanoclay scaffolds for bone tissue engineering

    Science.gov (United States)

    Ambre, Avinash Harishchandra

    Tissue engineering offers a significant potential alternative to conventional methods for rectifying tissue defects by evoking natural regeneration process via interactions between cells and 3D porous scaffolds. Imparting adequate mechanical properties to biodegradable scaffolds for bone tissue engineering is an important challenge and extends from molecular to macroscale. This work focuses on the use of sodium montmorillonite (Na-MMT) to design polymer composite scaffolds having enhanced mechanical properties along with multiple interdependent properties. Materials design beginning at the molecular level was used in which Na-MMT clay was modified with three different unnatural amino acids and further characterized using Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD). Based on improved bicompatibility with human osteoblasts (bone cells) and intermediate increase in d-spacing of MMT clay (shown by XRD), 5-aminovaleric acid modified clay was further used to prepare biopolymer (chitosan-polygalacturonic acid complex) scaffolds. Osteoblast proliferation in biopolymer scaffolds containing 5-aminovaleric acid modified clay was similar to biopolymer scaffolds containing hydroxyapatite (HAP). A novel process based on biomineralization in bone was designed to prepare 5-aminovaleric acid modified clay capable of imparting multiple properties to the scaffolds. Bone-like apatite was mineralized in modified clay and a novel nanoclay-HAP hybrid (in situ HAPclay) was obtained. FTIR spectroscopy indicated a molecular level organic-inorganic association between the intercalated 5-aminovaleric acid and mineralized HAP. Osteoblasts formed clusters on biopolymer composite films prepared with different weight percent compositions of in situ HAPclay. Human MSCs formed mineralized nodules on composite films and mineralized extracellular matrix (ECM) in composite scaffolds without the use of osteogenic supplements. Polycaprolactone (PCL), a synthetic polymer, was

  8. Super dielectric capacitor using scaffold dielectric

    OpenAIRE

    Phillips, Jonathan

    2018-01-01

    Patent A capacitor having first and second electrodes and a scaffold dielectric. The scaffold dielectric comprises an insulating material with a plurality of longitudinal channels extending across the dielectric and filled with a liquid comprising cations and anions. The plurality of longitudinal channels are substantially parallel and the liquid within the longitudinal channels generally has an ionic strength of at least 0.1. Capacitance results from the migrations of...

  9. Relationship between health services, socioeconomic variables and inadequate weight gain among Brazilian children.

    Science.gov (United States)

    de Souza, A C; Peterson, K E; Cufino, E; Gardner, J; Craveiro, M V; Ascherio, A

    1999-01-01

    This ecological analysis assessed the relative contribution of behavioural, health services and socioeconomic variables to inadequate weight gain in infants (0-11 months) and children (12-23 months) in 140 municipalities in the State of Ceara, north-east Brazil. To assess the total effect of selected variables, we fitted three unique sets of multivariate linear regression models to the prevalence of inadequate weight gain in infants and in children. The final predictive models included variables from the three sets. Findings showed that participation in growth monitoring and urbanization were inversely and significantly associated with the prevalence of inadequate weight gain in infants, accounting for 38.3% of the variation. Female illiteracy rate, participation in growth monitoring and degree of urbanization were all positively associated with prevalence of inadequate weight gain in children. Together, these factors explained 25.6% of the variation. Our results suggest that efforts to reduce the average municipality-specific female illiteracy rate, in combination with participation in growth monitoring, may be effective in reducing municipality-level prevalence of inadequate weight gain in infants and children in Ceara.

  10. The association between inadequate prenatal care and future healthcare use among offspring in the Bedouin population.

    Science.gov (United States)

    Estis-Deaton, Asia; Sheiner, Eyal; Wainstock, Tamar; Landau, Daniella; Walfisch, Asnat

    2017-12-01

    To evaluate the impact of inadequate prenatal care on long-term morbidity among the offspring of an ethnic minority population. A retrospective population-based cohort analysis was performed among all Bedouin women with singleton pregnancies who delivered in a tertiary medical center in Israel between January 1, 1991, and January 1, 2014. Morbidity was defined as pediatric hospitalization across six distinct disease categories before 18 years of age. The cumulative morbidity rates were compared for offspring born following pregnancies with either inadequate (prenatal care facility) or adequate prenatal care. Overall, 127 396 neonates were included; 19 173 (15.0%) were born following inadequate prenatal care. Pediatric hospitalizations for all morbidities other than cardiovascular ones were less frequent among the inadequate prenatal care group than the adequate prenatal care group (Pprenatal care group, with the exception of cardiovascular disease. Inadequate prenatal care correlated with reduced pediatric hospitalization rates among offspring, possibly owing to a lack of child healthcare service utilization within the Bedouin population. © 2017 International Federation of Gynecology and Obstetrics.

  11. Consequences of Inadequate Staffing Include Missed Care, Potential Failure to Rescue, and Job Stress and Dissatisfaction.

    Science.gov (United States)

    Simpson, Kathleen Rice; Lyndon, Audrey; Ruhl, Catherine

    2016-01-01

    To evaluate responses of registered nurse members of the Association of Women's Health, Obstetric and Neonatal Nurses (AWHONN) to a survey that sought their recommendations for staffing guidelines and their perceptions of the consequences of inadequate nurse staffing. The goal was to use these member data to inform the work of the AWHONN nurse staffing research team. Secondary analysis of responses to the 2010 AWHONN nurse staffing survey. Online. AWHONN members (N = 884). Review of data from an online survey of AWHONN members through the use of thematic analysis for descriptions of the consequences of inadequate nurse staffing during the childbirth process. Three main themes emerged as consequences of inadequate staffing or being short-staffed: Missed Care, Potential for Failure to Rescue, and Job-Related Stress and Dissatisfaction. These themes are consistent with those previously identified in the literature related to inadequate nurse staffing. Based on the responses from participants in the 2010 AWHONN nurse staffing survey, consequences of inadequate staffing can be quite serious and may put patients at risk for preventable harm. Copyright © 2016 AWHONN, the Association of Women's Health, Obstetric and Neonatal Nurses. Published by Elsevier Inc. All rights reserved.

  12. A review: fabrication of porous polyurethane scaffolds.

    Science.gov (United States)

    Janik, H; Marzec, M

    2015-03-01

    The aim of tissue engineering is the fabrication of three-dimensional scaffolds that can be used for the reconstruction and regeneration of damaged or deformed tissues and organs. A wide variety of techniques have been developed to create either fibrous or porous scaffolds from polymers, metals, composite materials and ceramics. However, the most promising materials are biodegradable polymers due to their comprehensive mechanical properties, ability to control the rate of degradation and similarities to natural tissue structures. Polyurethanes (PUs) are attractive candidates for scaffold fabrication, since they are biocompatible, and have excellent mechanical properties and mechanical flexibility. PU can be applied to various methods of porous scaffold fabrication, among which are solvent casting/particulate leaching, thermally induced phase separation, gas foaming, emulsion freeze-drying and melt moulding. Scaffold properties obtained by these techniques, including pore size, interconnectivity and total porosity, all depend on the thermal processing parameters, and the porogen agent and solvents used. In this review, various polyurethane systems for scaffolds are discussed, as well as methods of fabrication, including the latest developments, and their advantages and disadvantages. Copyright © 2014. Published by Elsevier B.V.

  13. Scaffolds for peripheral nerve repair and reconstruction.

    Science.gov (United States)

    Yi, Sheng; Xu, Lai; Gu, Xiaosong

    2018-06-02

    Trauma-associated peripheral nerve defect is a widespread clinical problem. Autologous nerve grafting, the current gold standard technique for the treatment of peripheral nerve injury, has many internal disadvantages. Emerging studies showed that tissue engineered nerve graft is an effective substitute to autologous nerves. Tissue engineered nerve graft is generally composed of neural scaffolds and incorporating cells and molecules. A variety of biomaterials have been used to construct neural scaffolds, the main component of tissue engineered nerve graft. Synthetic polymers (e.g. silicone, polyglycolic acid, and poly(lactic-co-glycolic acid)) and natural materials (e.g. chitosan, silk fibroin, and extracellular matrix components) are commonly used along or together to build neural scaffolds. Many other materials, including the extracellular matrix, glass fabrics, ceramics, and metallic materials, have also been used to construct neural scaffolds. These biomaterials are fabricated to create specific structures and surface features. Seeding supporting cells and/or incorporating neurotrophic factors to neural scaffolds further improve restoration effects. Preliminary studies demonstrate that clinical applications of these neural scaffolds achieve satisfactory functional recovery. Therefore, tissue engineered nerve graft provides a good alternative to autologous nerve graft and represents a promising frontier in neural tissue engineering. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. Strategies for osteochondral repair: Focus on scaffolds

    Directory of Open Access Journals (Sweden)

    Seog-Jin Seo

    2014-07-01

    Full Text Available Interest in osteochondral repair has been increasing with the growing number of sports-related injuries, accident traumas, and congenital diseases and disorders. Although therapeutic interventions are entering an advanced stage, current surgical procedures are still in their infancy. Unlike other tissues, the osteochondral zone shows a high level of gradient and interfacial tissue organization between bone and cartilage, and thus has unique characteristics related to the ability to resist mechanical compression and restoration. Among the possible therapies, tissue engineering of osteochondral tissues has shown considerable promise where multiple approaches of utilizing cells, scaffolds, and signaling molecules have been pursued. This review focuses particularly on the importance of scaffold design and its role in the success of osteochondral tissue engineering. Biphasic and gradient composition with proper pore configurations are the basic design consideration for scaffolds. Surface modification is an essential technique to improve the scaffold function associated with cell regulation or delivery of signaling molecules. The use of functional scaffolds with a controllable delivery strategy of multiple signaling molecules is also considered a promising therapeutic approach. In this review, we updated the recent advances in scaffolding approaches for osteochondral tissue engineering.

  15. Signs, dispositions, and semiotic scaffolding.

    Science.gov (United States)

    Fernández, Eliseo

    2015-12-01

    scaffolding. These interactions transpire between energetic causal chains and a wide range of converging semiotic transactions unfolding within each individual organism and between organisms and their environment. The perspective advanced here helps elucidate the manner in which physical and semiotic causation cooperate in an orchestrated fashion, giving rise to an ever-expanding profusion of scaffolding structures and processes. Using simple examples I outline some mechanisms that bring about this orchestration as well as the resultant channeling activities that eventually merge and find their culmination in the enactment of goal-oriented behavior. Copyright © 2015. Published by Elsevier Ltd.

  16. Predicting Patients with Inadequate 24- or 48-Hour Urine Collections at Time of Metabolic Stone Evaluation.

    Science.gov (United States)

    McGuire, Barry B; Bhanji, Yasin; Sharma, Vidit; Frainey, Brendan T; McClean, Megan; Dong, Caroline; Rimar, Kalen; Perry, Kent T; Nadler, Robert B

    2015-06-01

    We aimed to understand the characteristics of patients who are less likely to submit adequate urine collections at metabolic stone evaluation. Inadequate urine collection was defined using two definitions: (1) Reference ranges for 24-hour creatinine/kilogram (Cr/24) and (2) discrepancy in total 24-hour urine Cr between 24-hour urine collections. There were 1502 patients with ≥1 kidney stone between 1998 and 2014 who performed a 24- or 48-hour urine collection at Northwestern Memorial Hospital and who were identified retrospectively. Multivariate analysis was performed to analyze predictor variables for adequate urine collection. A total of 2852 urine collections were analyzed. Mean age for males was 54.4 years (range 17-86), and for females was 50.2 years (range 8-90). One patient in the study was younger than 17 years old. (1) Analysis based on the Cr 24/kg definition: There were 50.7% of patients who supplied an inadequate sample. Females were nearly 50% less likely to supply an adequate sample compared with men, Pcollections were achieved in 82.8%, 66.9%, 51.7%, 38.5%, and 26.4% of patients, respectively. Statistical significance was observed based on differences of ≥40%, and this was defined as the threshold for an inadequate sample. Female sex (OR 0.73 [0.54-0.98], P=0.037) predicted supplying inadequate samples. Adequate collections were more likely to be received on a Sunday (OR 1.6 [1.03-2.58], P=0.038) and by sedentary workers (OR 2.3 [1.12-4.72], P=0.023). Urine collections from patients during metabolic evaluation for nephrolithiasis may be considered inadequate based on two commonly used clinical definitions. This may have therapeutic or economic ramifications and the propensity for females to supply inadequate samples should be investigated further.

  17. Tubular inverse opal scaffolds for biomimetic vessels

    Science.gov (United States)

    Zhao, Ze; Wang, Jie; Lu, Jie; Yu, Yunru; Fu, Fanfan; Wang, Huan; Liu, Yuxiao; Zhao, Yuanjin; Gu, Zhongze

    2016-07-01

    There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially oriented elliptical pattern microstructures on their surfaces. It is demonstrated that these tailored tubular scaffolds can effectively make endothelial cells to form an integrated hollow tubular structure on their inner surface and induce smooth muscle cells to form a circumferential orientation on their outer surface. These features of our tubular scaffolds make them highly promising for the construction of biomimetic blood vessels.There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially

  18. Skull-base Osteomyelitis: a Dreaded Complication after Trivial Fall and Inadequate Management

    Directory of Open Access Journals (Sweden)

    Kundan Mittal

    2015-10-01

    Full Text Available Introduction: Skull-based osteomyelitis is bony infection which generally originates from inadequately treated chronic infection, adjoining tissue infection or after trauma.Case: 11 month female child had a trivial fall while standing near a bucket. The child developed fracture of right clavicle and left orbital swelling which was inadequately treated. This resulted in in spread of infection to adjoining tissues, skull bones, sinuses and brain.Conclusion: Cranial base osteomyelitis is rare but dreaded condition which requires early diagnosis and prompt treatment to avoid mortality and morbidity in form of neurological deficits and permanent disability

  19. Executive cognitive impairment detected by simple bedside testing ...

    African Journals Online (AJOL)

    Aims. Cognitive impairment in people with type 2 diabetes is a barrier to successful disease management. We sought to determine whether impaired executive function as detected by a battery of simple bedside cognitive tests of executive function was associated with inadequate glycaemic control. Methods. People with ...

  20. DNA-scaffolded nanoparticle structures

    Energy Technology Data Exchange (ETDEWEB)

    Hoegberg, Bjoern; Olin, Haakan [Department of Engineering Physics and Mathematics, Mid Sweden University, SE-851 70 Sundsvall, Sweden (Sweden)

    2007-03-15

    DNA self-assembly is a powerful route to the production of very small, complex structures. When used in combination with nanoparticles it is likely to become a key technology in the production of nanoelectronics in the future. Previously, demonstrated nanoparticle assemblies have mainly been periodic and highly symmetric arrays, unsuited as building blocks for any complex circuits. With the invention of DNA-scaffolded origami reported earlier this year (Rothemund P W K 2006 Nature 440 (7082) 297-302), a new route to complex nanostructures using DNA has been opened. Here, we give a short review of the field and present the current status of our experiments were DNA origami is used in conjunction with nanoparticles. Gold nanoparticles are functionalized with thiolated single stranded DNA. Strands that are complementary to the gold particle strands can be positioned on the self-assembled DNA-structure in arbitrary patterns. This property should allow an accurate positioning of the particles by letting them hybridize on the lattice. We report on our recent experiments on this system and discuss open problems and future applications.

  1. DNA-scaffolded nanoparticle structures

    International Nuclear Information System (INIS)

    Hoegberg, Bjoern; Olin, Haakan

    2007-01-01

    DNA self-assembly is a powerful route to the production of very small, complex structures. When used in combination with nanoparticles it is likely to become a key technology in the production of nanoelectronics in the future. Previously, demonstrated nanoparticle assemblies have mainly been periodic and highly symmetric arrays, unsuited as building blocks for any complex circuits. With the invention of DNA-scaffolded origami reported earlier this year (Rothemund P W K 2006 Nature 440 (7082) 297-302), a new route to complex nanostructures using DNA has been opened. Here, we give a short review of the field and present the current status of our experiments were DNA origami is used in conjunction with nanoparticles. Gold nanoparticles are functionalized with thiolated single stranded DNA. Strands that are complementary to the gold particle strands can be positioned on the self-assembled DNA-structure in arbitrary patterns. This property should allow an accurate positioning of the particles by letting them hybridize on the lattice. We report on our recent experiments on this system and discuss open problems and future applications

  2. Modifying bone scaffold architecture in vivo with permanent magnets to facilitate fixation of magnetic scaffolds.

    Science.gov (United States)

    Panseri, S; Russo, A; Sartori, M; Giavaresi, G; Sandri, M; Fini, M; Maltarello, M C; Shelyakova, T; Ortolani, A; Visani, A; Dediu, V; Tampieri, A; Marcacci, M

    2013-10-01

    The fundamental elements of tissue regeneration are cells, biochemical signals and the three-dimensional microenvironment. In the described approach, biomineralized-collagen biomaterial functions as a scaffold and provides biochemical stimuli for tissue regeneration. In addition superparamagnetic nanoparticles were used to magnetize the biomaterials with direct nucleation on collagen fibres or impregnation techniques. Minimally invasive surgery was performed on 12 rabbits to implant cylindrical NdFeB magnets in close proximity to magnetic scaffolds within the lateral condyles of the distal femoral epiphyses. Under this static magnetic field we demonstrated, for the first time in vivo, that the ability to modify the scaffold architecture could influence tissue regeneration obtaining a well-ordered tissue. Moreover, the association between NdFeB magnet and magnetic scaffolds represents a potential technique to ensure scaffold fixation avoiding micromotion at the tissue/biomaterial interface. © 2013.

  3. Biodegradable Polymer-Based Scaffolds for Bone Tissue Engineering

    CERN Document Server

    Sultana, Naznin

    2013-01-01

    This book addresses the principles, methods and applications of biodegradable polymer based scaffolds for bone tissue engineering. The general principle of bone tissue engineering is reviewed and the traditional and novel scaffolding materials, their properties and scaffold fabrication techniques are explored. By acting as temporary synthetic extracellular matrices for cell accommodation, proliferation, and differentiation, scaffolds play a pivotal role in tissue engineering. This book does not only provide the comprehensive summary of the current trends in scaffolding design but also presents the new trends and directions for scaffold development for the ever expanding tissue engineering applications.

  4. Computational design of new molecular scaffolds for medicinal chemistry, part II: generalization of analog series-based scaffolds

    Science.gov (United States)

    Dimova, Dilyana; Stumpfe, Dagmar; Bajorath, Jürgen

    2018-01-01

    Aim: Extending and generalizing the computational concept of analog series-based (ASB) scaffolds. Materials & methods: Methodological modifications were introduced to further increase the coverage of analog series (ASs) and compounds by ASB scaffolds. From bioactive compounds, ASs were systematically extracted and second-generation ASB scaffolds isolated. Results: More than 20,000 second-generation ASB scaffolds with single or multiple substitution sites were extracted from active compounds, achieving more than 90% coverage of ASs. Conclusion: Generalization of the ASB scaffold approach has yielded a large knowledge base of scaffold-capturing compound series and target information. PMID:29379641

  5. Risk factors for and consequences of inadequate surgical margins in oral squamous cell carcinoma

    DEFF Research Database (Denmark)

    Lawaetz, Mads; Homøe, Preben

    2014-01-01

    OBJECTIVE: The purpose of this study was to examine which factors are associated with inadequate surgical margins and to assess the postoperative consequences. STUDY DESIGN: A retrospective cohort of 110 patients with oral squamous cell carcinoma treated with surgery during a 2-year period...

  6. Self-esteem, social support, and satisfaction differences in women with adequate and inadequate prenatal care.

    Science.gov (United States)

    Higgins, P; Murray, M L; Williams, E M

    1994-03-01

    This descriptive, retrospective study examined levels of self-esteem, social support, and satisfaction with prenatal care in 193 low-risk postpartal women who obtained adequate and inadequate care. The participants were drawn from a regional medical center and university teaching hospital in New Mexico. A demographic questionnaire, the Coopersmith self-esteem inventory, the personal resource questionnaire part 2, and the prenatal care satisfaction inventory were used for data collection. Significant differences were found in the level of education, income, insurance, and ethnicity between women who received adequate prenatal care and those who received inadequate care. Women who were likely to seek either adequate or inadequate prenatal care were those whose total family income was $10,000 to $19,999 per year and high school graduates. Statistically significant differences were found in self-esteem, social support, and satisfaction between the two groups of women. Strategies to enhance self-esteem and social support have to be developed to reach women at risk for receiving inadequate prenatal care.

  7. 25 CFR 170.811 - What happens if lack of funds results in inadequate maintenance?

    Science.gov (United States)

    2010-04-01

    ... maintenance? 170.811 Section 170.811 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER INDIAN RESERVATION ROADS PROGRAM BIA Road Maintenance § 170.811 What happens if lack of funds results in inadequate maintenance? If BIA determines that an IRR transportation facility is not being...

  8. Do infants with cow's milk protein allergy have inadequate levels of vitamin D?

    Science.gov (United States)

    Silva, Cristiane M; Silva, Silvia A da; Antunes, Margarida M de C; Silva, Gisélia Alves Pontes da; Sarinho, Emanuel Sávio Cavalcanti; Brandt, Katia G

    To verify whether infants with cow's milk protein allergy have inadequate vitamin D levels. This cross-sectional study included 120 children aged 2 years or younger, one group with cow's milk protein allergy and a control group. The children were recruited at the pediatric gastroenterology, allergology, and pediatric outpatient clinics of a university hospital in the Northeast of Brazil. A questionnaire was administered to the caregiver and blood samples were collected for vitamin D quantification. Vitamin D levels <30ng/mL were considered inadequate. Vitamin D level was expressed as mean and standard deviation, and the frequency of the degrees of sufficiency and other variables, as proportions. Infants with cow's milk protein allergy had lower mean vitamin D levels (30.93 vs.35.29ng/mL; p=0.041) and higher deficiency frequency (20.3% vs.8.2; p=0.049) than the healthy controls. Exclusively or predominantly breastfed infants with cow's milk protein allergy had higher frequency of inadequate vitamin D levels (p=0.002). Regardless of sun exposure time, the groups had similar frequencies of inadequate vitamin D levels (p=0.972). Lower vitamin D levels were found in infants with CMPA, especially those who were exclusively or predominantly breastfed, making these infants a possible risk group for vitamin D deficiency. Copyright © 2017 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  9. The Influence of Inadequate Teacher-to-Student Social Support on Amotivation of Physical Education Students

    Science.gov (United States)

    Shen, Bo; Li, Weidong; Sun, Haichun; Rukavina, Paul Bernard

    2010-01-01

    Guided by Green-Demers, Leagult, Pelletier, and Pelletier's (2008) assumption that amotivation (absence of motivation) is a multidimensional construct, we designed this study to investigate the influence of inadequate teacher-to-student social support on amotivation of high-school physical education students. Five hundred and sixty-six ninth…

  10. Randomized Trial of Once-Daily Fluticasone Furoate in Children with Inadequately Controlled Asthma

    DEFF Research Database (Denmark)

    Oliver, Amanda J.; Covar, Ronina A.; Goldfrad, Caroline H.

    2016-01-01

    Objective To evaluate the dose-response, efficacy, and safety of fluticasone furoate (FF; 25 µg, 50 µg, and 100 µg), administered once daily in the evening during a 12-week treatment period to children with inadequately controlled asthma. Study design This was a Phase IIb, multicenter, stratified...

  11. Do infants with cow's milk protein allergy have inadequate levels of vitamin D?

    Directory of Open Access Journals (Sweden)

    Cristiane M. Silva

    Full Text Available Abstract Objective: To verify whether infants with cow's milk protein allergy have inadequate vitamin D levels. Methods: This cross-sectional study included 120 children aged 2 years or younger, one group with cow's milk protein allergy and a control group. The children were recruited at the pediatric gastroenterology, allergology, and pediatric outpatient clinics of a university hospital in the Northeast of Brazil. A questionnaire was administered to the caregiver and blood samples were collected for vitamin D quantification. Vitamin D levels <30 ng/mL were considered inadequate. Vitamin D level was expressed as mean and standard deviation, and the frequency of the degrees of sufficiency and other variables, as proportions. Results: Infants with cow's milk protein allergy had lower mean vitamin D levels (30.93 vs.35.29 ng/mL; p = 0.041 and higher deficiency frequency (20.3% vs.8.2; p = 0.049 than the healthy controls. Exclusively or predominantly breastfed infants with cow's milk protein allergy had higher frequency of inadequate vitamin D levels (p = 0.002. Regardless of sun exposure time, the groups had similar frequencies of inadequate vitamin D levels (p = 0.972. Conclusions: Lower vitamin D levels were found in infants with CMPA, especially those who were exclusively or predominantly breastfed, making these infants a possible risk group for vitamin D deficiency.

  12. 76 FR 33780 - Assessments for Mismatched Payments or Inadequate Payment Information for Geothermal, Solid...

    Science.gov (United States)

    2011-06-09

    ...] Assessments for Mismatched Payments or Inadequate Payment Information for Geothermal, Solid Minerals, and...: Regulations for geothermal, solid minerals, and Indian oil and gas leases authorize the Office of Natural..., Office of Natural Resources Revenue, P.O. Box 25165, MS 61211B, Denver, Colorado 80225-0165...

  13. Two Kinds of Scaffolding: The Dialectical Process within the Authenticity-Generalizibility (A-G Continuum

    Directory of Open Access Journals (Sweden)

    Hung W. L. David

    2002-10-01

    Full Text Available Recent developments of situated cognition seem to be incompatible with traditional views of school based-learning where abstract or generalized knowledge is emphasized. In this paper, we are advocating that authenticity (as emphasized by situated cognitivists and generalizibility (as advocated by cognitivists are compatible. From an instructional perspective, it should not be for one or the other, but rather the scaffolding of the dialecticism between authenticity and generalizibility. In this paper, we first discuss the problems relating to the radical view of situated cognition and cognitivist approaches to learning and instruction. We then contend that authenticity and generalizibility are compatible and introduce the notion of the Authenticity-Generalizibility (A-G continuum, where from an instructional perspective, the emphasis should be scaffolding within such a continuum. We hypothesize that learners would have richer and deeper understandings of a subject or domain when they have opportunities to experience the full range of learning activities within the A-G continuum. Finally, we proposed two kinds of IT scaffolds, one to assist student moving towards the authenticity end of the continuum and the other vice versa.

  14. Improving Students' Speaking Ability through Scaffolding Technique

    Directory of Open Access Journals (Sweden)

    Gede Ginaya

    2018-03-01

    Full Text Available Students often got confused and felt hesitant when they speak English. This situation had caused poor speaking ability, which then lead to serious problem in the teaching-learning process.  The application of scaffolding technique in the EFL learning might be the ideal solution; it had some principles that could improve the students’ speaking ability. This research is aimed at finding out the effect of the implementing Scaffolding Technique towards the students’ speaking ability. Participants were 50 (27 males and 23 females third-semester students, enrolled in a three-year diploma program in Travel and Tourism Business, State Polytechnic of Bali in 2017/2018 academic year. The students in the experimental group were given communicative activities such as brainstorming, business games, simulation, WebQuest, problem-solving, which were carefully designed to necessitate the implementation of the scaffolding technique. The students in the control group were taught by the deductive method of the lesson book. The students’ performance in the post-test was compared for both groups in order to determine whether there were significant differences between the groups in relation to the treatment. Significant differences occurring in the experimental group’s post-test speaking performance when compared to the pre-test indicate that the implementation of scaffolding technique can improve students’ speaking ability. The result of this study indicates scaffolding technique has the potential for use in promoting students’ speaking ability

  15. Heterogeneity of Scaffold Biomaterials in Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Lauren Edgar

    2016-05-01

    Full Text Available Tissue engineering (TE offers a potential solution for the shortage of transplantable organs and the need for novel methods of tissue repair. Methods of TE have advanced significantly in recent years, but there are challenges to using engineered tissues and organs including but not limited to: biocompatibility, immunogenicity, biodegradation, and toxicity. Analysis of biomaterials used as scaffolds may, however, elucidate how TE can be enhanced. Ideally, biomaterials should closely mimic the characteristics of desired organ, their function and their in vivo environments. A review of biomaterials used in TE highlighted natural polymers, synthetic polymers, and decellularized organs as sources of scaffolding. Studies of discarded organs supported that decellularization offers a remedy to reducing waste of donor organs, but does not yet provide an effective solution to organ demand because it has shown varied success in vivo depending on organ complexity and physiological requirements. Review of polymer-based scaffolds revealed that a composite scaffold formed by copolymerization is more effective than single polymer scaffolds because it allows copolymers to offset disadvantages a single polymer may possess. Selection of biomaterials for use in TE is essential for transplant success. There is not, however, a singular biomaterial that is universally optimal.

  16. Scaffolds in regenerative endodontics: A review

    Science.gov (United States)

    Gathani, Kinjal M.; Raghavendra, Srinidhi Surya

    2016-01-01

    Root canal therapy has enabled us to save numerous teeth over the years. The most desired outcome of endodontic treatment would be when diseased or nonvital pulp is replaced with healthy pulp tissue that would revitalize the teeth through regenerative endodontics. ‘A search was conducted using the Pubmed and MEDLINE databases for articles with the criteria ‘Platelet rich plasma’, ‘Platelet rich fibrin’, ‘Stem cells’, ‘Natural and artificial scaffolds’ from 1982–2015’. Tissues are organized as three-dimensional structures, and appropriate scaffolding is necessary to provide a spatially correct position of cell location and regulate differentiation, proliferation, or metabolism of the stem cells. Extracellular matrix molecules control the differentiation of stem cells, and an appropriate scaffold might selectively bind and localize cells, contain growth factors, and undergo biodegradation over time. Different scaffolds facilitate the regeneration of different tissues. To ensure a successful regenerative procedure, it is essential to have a thorough and precise knowledge about the suitable scaffold for the required tissue. This article gives a review on the different scaffolds providing an insight into the new developmental approaches on the horizon. PMID:27857762

  17. Scaffolds in regenerative endodontics: A review

    Directory of Open Access Journals (Sweden)

    Kinjal M Gathani

    2016-01-01

    Full Text Available Root canal therapy has enabled us to save numerous teeth over the years. The most desired outcome of endodontic treatment would be when diseased or nonvital pulp is replaced with healthy pulp tissue that would revitalize the teeth through regenerative endodontics. ′A search was conducted using the Pubmed and MEDLINE databases for articles with the criteria ′Platelet rich plasma′, ′Platelet rich fibrin′, ′Stem cells′, ′Natural and artificial scaffolds′ from 1982-2015′. Tissues are organized as three-dimensional structures, and appropriate scaffolding is necessary to provide a spatially correct position of cell location and regulate differentiation, proliferation, or metabolism of the stem cells. Extracellular matrix molecules control the differentiation of stem cells, and an appropriate scaffold might selectively bind and localize cells, contain growth factors, and undergo biodegradation over time. Different scaffolds facilitate the regeneration of different tissues. To ensure a successful regenerative procedure, it is essential to have a thorough and precise knowledge about the suitable scaffold for the required tissue. This article gives a review on the different scaffolds providing an insight into the new developmental approaches on the horizon.

  18. In vitro osteoclastogenesis on textile chitosan scaffold

    Directory of Open Access Journals (Sweden)

    C Heinemann

    2010-02-01

    Full Text Available Textile chitosan fibre scaffolds were evaluated in terms of interaction with osteoclast-like cells, derived from human primary monocytes. Part of the scaffolds was further modified by coating with fibrillar collagen type I in order to make the surface biocompatible. Monocytes were cultured directly on the scaffolds in the presence of macrophage colony stimulating factor (M-CSF and receptor activator of nuclear factor kappaB ligand (RANKL for up to 18 days. Confocal laser scanning microscopy (CLSM as well as scanning electron microscopy (SEM revealed the formation of multinuclear osteoclast-like cells on both the raw chitosan fibres and the collagen-coated scaffolds. The modified surface supported the osteoclastogenesis. Differentiation towards the osteoclastic lineage was confirmed by the microscopic detection of cathepsin K, tartrate resistant acid phosphatase (TRAP, acidic compartments using 3-(2,4-dinitroanillino-3’-amino-N-methyldipropylamine (DAMP, immunological detection of TRAP isoform 5b, and analysis of gene expression of the osteoclastic markers TRAP, cathepsin K, vitronectin receptor, and calcitonin receptor using reverse transcription-polymerase chain reaction (RT-PCR. The feature of the collagen-coated but also of the raw chitosan fibre scaffolds to support attachment and differentiation of human monocytes facilitates cell-induced material resorption – one main requirement for successful bone tissue engineering.

  19. Cognitive Changes

    Science.gov (United States)

    ... are here Home › Non-Movement Symptoms › Cognitive Changes Cognitive Changes Some people with Parkinson’s disease (PD) experience mild cognitive impairment. Feelings of distraction or disorganization can accompany ...

  20. A Guide to Scaffold Use in the Construction Industry

    National Research Council Canada - National Science Library

    2001-01-01

    On August 30, 1996, OSHA issued revised standards for scaffolds. The revised standard, known as "Safety Standards for Scaffolds Used in the Construction Industry" is found in Title 29 Code of Federal Regulations (CFR) Part, Subpart L...

  1. Biodegradation and bioresorption of poly(-caprolactone) nanocomposite scaffolds

    CSIR Research Space (South Africa)

    Mkhabela, V

    2015-08-01

    Full Text Available confirmed the elemental composition of the scaffolds. The phase composition of the scaffolds was shown by XRD, which also indicated a decrease in crystallinity with the introduction of nanoclay. Biodegradability studies which were conducted in simulated...

  2. Knowledge scaffolding visualizations: A guiding framework

    Directory of Open Access Journals (Sweden)

    Elitsa Alexander

    2015-06-01

    Full Text Available In this paper we provide a guiding framework for understanding and selecting visual representations in the knowledge management (KM practice. We build on an interdisciplinary analogy between two connotations of the notion of “scaffolding”: physical scaffolding from an architectural-engineering perspective and scaffolding of the “everyday knowing in practice” from a KM perspective. We classify visual structures for knowledge communication in teams into four types of scaffolds: grounded (corresponding e.g., to perspectives diagrams or dynamic facilitation diagrams, suspended (e.g., negotiation sketches, argument maps, panel (e.g., roadmaps or timelines and reinforcing (e.g., concept diagrams. The article concludes with a set of recommendations in the form of questions to ask whenever practitioners are choosing visualizations for specific KM needs. Our recommendations aim at providing a framework at a broad-brush level to aid choosing a suitable visualization template depending on the type of KM endeavour.

  3. Nano/macro porous bioactive glass scaffold

    Science.gov (United States)

    Wang, Shaojie

    Bioactive glass (BG) and ceramics have been widely studied and developed as implants to replace hard tissues of the musculo-skeletal system, such as bones and teeth. Recently, instead of using bulk materials, which usually do not degrade rapidly enough and may remain in the human body for a long time, the idea of bioscaffold for tissue regeneration has generated much interest. An ideal bioscaffold is a porous material that would not only provide a three-dimensional structure for the regeneration of natural tissue, but also degrade gradually and, eventually be replaced by the natural tissue completely. Among various material choices the nano-macro dual porous BG appears as the most promising candidate for bioscaffold applications. Here macropores facilitate tissue growth while nanopores control degradation and enhance cell response. The surface area, which controls the degradation of scaffold can also be tuned by changing the nanopore size. However, fabrication of such 3D structure with desirable nano and macro pores has remained challenging. In this dissertation, sol-gel process combined with spinodal decomposition or polymer sponge replication method has been developed to fabricate the nano-macro porous BG scaffolds. Macropores up to 100microm are created by freezing polymer induced spinodal structure through sol-gel transition, while larger macropores (>200um) of predetermined size are obtained by the polymer sponge replication technique. The size of nanopores, which are inherent to the sol-gel method of glass fabrication, has been tailored using several approaches: Before gel point, small nanopores are generated using acid catalyst that leads to weakly-branched polymer-like network. On the other hand, larger nanopores are created with the base-catalyzed gel with highly-branched cluster-like structure. After the gel point, the nanostructure can be further modified by manipulating the sintering temperature and/or the ammonia concentration used in the solvent

  4. Cognitive Challenges

    Science.gov (United States)

    ... Privacy Policy Sitemap Learn Engage Donate About TSC Cognitive Challenges Approximately 45% to 60% of individuals with TSC develop cognitive challenges (intellectual disabilities), although the degree of intellectual ...

  5. SCAFFOLDING IN CONNECTIVIST MOBILE LEARNING ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Ozlem OZAN

    2013-04-01

    Full Text Available Social networks and mobile technologies are transforming learning ecology. In this changing learning environment, we find a variety of new learner needs. The aim of this study is to investigate how to provide scaffolding to the learners in connectivist mobile learning environment: Ø to learn in a networked environment, Ø to manage their networked learning process, Ø to interact in a networked society, and Ø to use the tools belonging to the network society. The researcher described how Vygotsky's “scaffolding” concept, Berge’s “learner support” strategies, and Siemens’ “connectivism” approach can be used together to satisfy mobile learners’ needs. A connectivist mobile learning environment was designed for the research, and the research was executed as a mixed-method study. Data collection tools were Facebook wall entries, personal messages, chat records; Twitter, Diigo, blog entries; emails, mobile learning management system statistics, perceived learning survey and demographic information survey. Results showed that there were four major aspects of scaffolding in connectivist mobile learning environment as type of it, provider of it, and timing of it and strategies of it. Participants preferred mostly social scaffolding, and then preferred respectively, managerial, instructional and technical scaffolding. Social scaffolding was mostly provided by peers, and managerial scaffolding was mostly provided by instructor. Use of mobile devices increased the learner motivation and interest. Some participants stated that learning was more permanent by using mobile technologies. Social networks and mobile technologies made it easier to manage the learning process and expressed a positive impact on perceived learning.

  6. Scaffolding students’ reflective dialogues in the chemistry lab: challenging the cookbook

    DEFF Research Database (Denmark)

    Nielsen, Birgitte Lund; Hougaard, Rikke Frøhlich

    The paper reports on a cross-case analysis comparing students’ activities and dialogue during BA level laboratory exercises, applying a mixed methods research design with video-data, student questionnaires and interviews. Our analysis identified specific affordances in relation to macro and micro......-scaffolding of students’ activities and dialogues, in order to stimulate them to work at higher cognitive levels. A specific lab-exercise in the course Macroscopic Physical Chemistry was redesigned with the aim of stimulating students’ metacognition both before and during the experimental work. The redesign included......-student dialogue on course content. Furthermore, dialogues between students and teaching assistant revealed elements of micro-scaffolding exploratory talk and a dialogic approach with open questions and prompts. The students expressed that the preparatory assignments and the dialogue with the teaching assistant...

  7. The importance of providing scaffolding to support patient narratives when brain damage impairs storytelling ability.

    Science.gov (United States)

    Hydén, Lars C

    2011-01-01

    Boundaries connected to illness are defined and redefined through new ways of interacting with other people and especially by storytelling and listening to the stories of others. Diseases or traumas that affect the brain can result in memory loss, impaired cognition, and difficulties in expressing oneself clearly, hence making it difficult to present and negotiate identities. In such situations, others often try to remedy the communicative problems by taking over those narrative functions that are lost or impaired and thereby scaffolding the injured person's storytelling capacity. This narrative scaffolding is directed at keeping interpersonal relationships functional and makes it possible for persons with communicative disabilities to continue to be participants in a shared life.

  8. Simulations as Scaffolds in Science Education

    DEFF Research Database (Denmark)

    Renken, Maggie; Peffer, Melanie; Otrel-Cass, Kathrin

    This book outlines key issues for addressing the grand challenges posed to educators, developers, and researchers interested in the intersection of simulations and science education. To achieve this, the authors explore the use of computer simulations as instructional scaffolds that provide...... strategies and support when students are faced with the need to acquire new skills or knowledge. The monograph aims to provide insight into what research has reported on navigating the complex process of inquiry- and problem-based science education and whether computer simulations as instructional scaffolds...

  9. Scaffold Diversity from N-Acyliminium Ions

    DEFF Research Database (Denmark)

    Wu, Peng; Nielsen, Thomas E

    2017-01-01

    N-Acyliminium ions are powerful reactive species for the formation of carbon-carbon and carbon-heteroatom bonds. Strategies relying on intramolecular reactions of N-acyliminium intermediates, also referred to as N-acyliminium ion cyclization reactions, have been employed for the construction...... of structurally diverse scaffolds, ranging from simple bicyclic skeletons to complex polycyclic systems and natural-product-like compounds. This review aims to provide an overview of cyclization reactions of N-acyliminium ions derived from various precursors for the assembly of structurally diverse scaffolds...

  10. Scaffolds of polycaprolactone with hydroxyapatite fibers

    International Nuclear Information System (INIS)

    Cardoso, Guinea B.C.; Zavaglia, Cecilia A.C.; Arruda, Antonio Celso F.

    2009-01-01

    Scaffolds of poly (ε-caprolactone) has been studied in many researches in tissue engineering. The used of hydroxyapatite fibers, allowed increase its resistance mechanical, beside the character bioactive and osteoconductive. Improving, its role in tissue engineering. The aim in this study was developed polycaprolactone matrix with dispersed hydroxyapatite fibers. The characterizations were by scanning electron microscopy (SEM), X- Ray Diffractometer (XRD), X-Ray Fluorescence (XRF) and Energy dispersive X-Ray Detector (EDX). Was able reviewed its composition, morphology and possible contaminations. The results were scaffolds with porosity and distribution of the fibers in all its area. (author)

  11. Bio-functionalized PCL nanofibrous scaffolds for nerve tissue engineering

    International Nuclear Information System (INIS)

    Ghasemi-Mobarakeh, Laleh; Prabhakaran, Molamma P.; Morshed, Mohammad; Nasr-Esfahani, Mohammad Hossein; Ramakrishna, S.

    2010-01-01

    Surface properties of scaffolds such as hydrophilicity and the presence of functional groups on the surface of scaffolds play a key role in cell adhesion, proliferation and migration. Different modification methods for hydrophilicity improvement and introduction of functional groups on the surface of scaffolds have been carried out on synthetic biodegradable polymers, for tissue engineering applications. In this study, alkaline hydrolysis of poly (ε-caprolactone) (PCL) nanofibrous scaffolds was carried out for different time periods (1 h, 4 h and 12 h) to increase the hydrophilicity of the scaffolds. The formation of reactive groups resulting from alkaline hydrolysis provides opportunities for further surface functionalization of PCL nanofibrous scaffolds. Matrigel was attached covalently on the surface of an optimized 4 h hydrolyzed PCL nanofibrous scaffolds and additionally the fabrication of blended PCL/matrigel nanofibrous scaffolds was carried out. Chemical and mechanical characterization of nanofibrous scaffolds were evaluated using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, contact angle, scanning electron microscopy (SEM) and tensile measurement. In vitro cell adhesion and proliferation study was carried out after seeding nerve precursor cells (NPCs) on different scaffolds. Results of cell proliferation assay and SEM studies showed that the covalently functionalized PCL/matrigel nanofibrous scaffolds promote the proliferation and neurite outgrowth of NPCs compared to PCL and hydrolyzed PCL nanofibrous scaffolds, providing suitable substrates for nerve tissue engineering.

  12. Patterns of Scaffolding in Computer-Mediated Collaborative Inquiry

    Science.gov (United States)

    Lakkala, Minna; Muukkonen, Hanni; Hakkarainen, Kai

    2005-01-01

    There is wide agreement on the importance of scaffolding for student learning. Yet, models of individual and face-to-face scaffolding are not necessarily applicable to educational settings in which a group of learners is pursuing a process of inquiry mediated by technology. The scaffolding needed for such a process may be examined from three…

  13. Heat stress and inadequate sanitary facilities at workplaces – an occupational health concern for women?

    Science.gov (United States)

    Venugopal, Vidhya; Rekha, Shanmugam; Manikandan, Krishnamoorthy; Latha, Perumal Kamalakkannan; Vennila, Viswanathan; Ganesan, Nalini; Kumaravel, Perumal; Chinnadurai, Stephen Jeremiah

    2016-01-01

    Background Health concerns unique to women are growing with the large number of women venturing into different trades that expose them to hot working environments and inadequate sanitation facilities, common in many Indian workplaces. Objective The study was carried out to investigate the health implications of exposures to hot work environments and inadequate sanitation facilities at their workplaces for women workers. Design A cross-sectional study was conducted with 312 women workers in three occupational sectors in 2014–2015. Quantitative data on heat exposures and physiological heat strain indicators such as core body temperature (CBT), sweat rate (SwR), and urine specific gravity (USG) were collected. A structured questionnaire captured workers perceptions about health impacts of heat stress and inadequate sanitary facilities at the workplace. Results Workplace heat exposures exceeded the threshold limit value for safe manual work for 71% women (Avg. wet bulb globe temperature=30°C±2.3°C) during the study period. Eighty-seven percent of the 200 women who had inadequate/no toilets at their workplaces reported experiencing genitourinary problems periodically. Above normal CBT, SwR, and USG in about 10% women workers indicated heat strain and moderate dehydration that corroborated well with their perceptions. Observed significant associations between high-heat exposures and SwR (t=−2.3879, p=0.0192), inadequate toilet facilities and self-reported adverse heat-related health symptoms (χ2=4.03, p=0.0444), and prevalence of genitourinary issues (χ2=42.92, p=0.0005×10−7) reemphasize that heat is a risk and lack of sanitation facilities is a major health concern for women workers. Conclusions The preliminary evidence suggests that health of women workers is at risk due to occupational heat exposures and inadequate sanitation facilities at many Indian workplaces. Intervention through strong labor policies with gender sensitivity is the need of the hour to

  14. Heat stress and inadequate sanitary facilities at workplaces – an occupational health concern for women?

    Directory of Open Access Journals (Sweden)

    Vidhya Venugopal

    2016-09-01

    Full Text Available Background: Health concerns unique to women are growing with the large number of women venturing into different trades that expose them to hot working environments and inadequate sanitation facilities, common in many Indian workplaces. Objective: The study was carried out to investigate the health implications of exposures to hot work environments and inadequate sanitation facilities at their workplaces for women workers. Design: A cross-sectional study was conducted with 312 women workers in three occupational sectors in 2014–2015. Quantitative data on heat exposures and physiological heat strain indicators such as core body temperature (CBT, sweat rate (SwR, and urine specific gravity (USG were collected. A structured questionnaire captured workers perceptions about health impacts of heat stress and inadequate sanitary facilities at the workplace. Results: Workplace heat exposures exceeded the threshold limit value for safe manual work for 71% women (Avg. wet bulb globe temperature=30°C±2.3°C during the study period. Eighty-seven percent of the 200 women who had inadequate/no toilets at their workplaces reported experiencing genitourinary problems periodically. Above normal CBT, SwR, and USG in about 10% women workers indicated heat strain and moderate dehydration that corroborated well with their perceptions. Observed significant associations between high-heat exposures and SwR (t=−2.3879, p=0.0192, inadequate toilet facilities and self-reported adverse heat-related health symptoms (χ2=4.03, p=0.0444, and prevalence of genitourinary issues (χ2=42.92, p=0.0005×10−7 reemphasize that heat is a risk and lack of sanitation facilities is a major health concern for women workers. Conclusions: The preliminary evidence suggests that health of women workers is at risk due to occupational heat exposures and inadequate sanitation facilities at many Indian workplaces. Intervention through strong labor policies with gender sensitivity is the

  15. Heat stress and inadequate sanitary facilities at workplaces - an occupational health concern for women?

    Science.gov (United States)

    Venugopal, Vidhya; Rekha, Shanmugam; Manikandan, Krishnamoorthy; Latha, Perumal Kamalakkannan; Vennila, Viswanathan; Ganesan, Nalini; Kumaravel, Perumal; Chinnadurai, Stephen Jeremiah

    2016-01-01

    Health concerns unique to women are growing with the large number of women venturing into different trades that expose them to hot working environments and inadequate sanitation facilities, common in many Indian workplaces. The study was carried out to investigate the health implications of exposures to hot work environments and inadequate sanitation facilities at their workplaces for women workers. A cross-sectional study was conducted with 312 women workers in three occupational sectors in 2014-2015. Quantitative data on heat exposures and physiological heat strain indicators such as core body temperature (CBT), sweat rate (SwR), and urine specific gravity (USG) were collected. A structured questionnaire captured workers perceptions about health impacts of heat stress and inadequate sanitary facilities at the workplace. Workplace heat exposures exceeded the threshold limit value for safe manual work for 71% women (Avg. wet bulb globe temperature=30°C±2.3°C) during the study period. Eighty-seven percent of the 200 women who had inadequate/no toilets at their workplaces reported experiencing genitourinary problems periodically. Above normal CBT, SwR, and USG in about 10% women workers indicated heat strain and moderate dehydration that corroborated well with their perceptions. Observed significant associations between high-heat exposures and SwR (t=-2.3879, p=0.0192), inadequate toilet facilities and self-reported adverse heat-related health symptoms (χ (2)=4.03, p=0.0444), and prevalence of genitourinary issues (χ (2)=42.92, p=0.0005×10(-7)) reemphasize that heat is a risk and lack of sanitation facilities is a major health concern for women workers. The preliminary evidence suggests that health of women workers is at risk due to occupational heat exposures and inadequate sanitation facilities at many Indian workplaces. Intervention through strong labor policies with gender sensitivity is the need of the hour to empower women, avert further health risks, and

  16. Magnitude and determinants of inadequate third-trimester weight gain in rural Bangladesh.

    Science.gov (United States)

    Hasan, S M Tafsir; Rahman, Sabuktagin; Locks, Lindsey Mina; Rahman, Mizanur; Hore, Samar Kumar; Saqeeb, Kazi Nazmus; Khan, Md Alfazal; Ahmed, Tahmeed

    2018-01-01

    The objective of this study was to estimate the magnitude and determinants of inadequate weight gain in the third-trimester among rural women in Matlab, Bangladesh. The study analyzed data on weight gain in the third trimester in 1,883 pregnant women in Matlab, Bangladesh. All these women were admitted to Matlab hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b) for childbirth during 2012-2014, and they had singleton live births at term. Data were retrieved from the electronic databases of Matlab Health and Demographic Surveillance System and Matlab hospital. A multivariable logistic regression for inadequate weight gain in the third trimester (≤4 kg) was built with sociodemographic, environmental and maternal factors as predictors. One thousand and twenty-six (54%) pregnant women had inadequate weight gain in the third trimester. In the multivariable model, short stature turned out to be the most robust risk factor for inadequate weight gain in the third trimester (OR = 2.5; 95% CI 1.8, 3.5 for short compared to tall women). Pre-third-trimester BMI was inversely associated with insufficient weight gain (OR = 0.96; 95% CI 0.93, 0.99 for 1 unit increase in BMI). Other risk factors for inadequate weight gain in the third trimester were advanced age (OR = 1.9; 95% CI 1.2, 3.1 for ≥35 years compared to ≤19 years), parity (OR = 1.5; 95% CI 1.2, 1.9 for multipara compared to nulliparous women), low socioeconomic status (OR = 1.7; 95% CI 1.2, 2.3 for women in the lowest compared to women in the highest wealth quintile), low level of education (OR = 1.6; 95% CI 1.2, 2.1 for ≤5 years compared to ≥10 years of education), belonging to the Hindu religious community (OR = 1.8; 95% CI 1.3, 2.5), consuming arsenic-contaminated water (OR = 1.4; 95% CI 1.1, 1.9), and conceiving during monsoon or dry season compared to summer (OR = 1.4; 95% CI 1.1, 1.8). Among rural Bangladeshi women in Matlab, third-trimester weight gain was in

  17. Language, embodiment, and the cognitive niche.

    Science.gov (United States)

    Clark, Andy

    2006-08-01

    Embodied agents use bodily actions and environmental interventions to make the world a better place to think in. Where does language fit into this emerging picture of the embodied, ecologically efficient agent? One useful way to approach this question is to consider language itself as a cognition-enhancing animal-built structure. To take this perspective is to view language as a kind of self-constructed cognitive niche: a persisting but never stationary material scaffolding whose crucial role in promoting thought and reason remains surprisingly poorly understood. It is the very materiality of this linguistic scaffolding, I suggest, that gives it some key benefits. By materializing thought in words, we create structures that are themselves proper objects of perception, manipulation, and (further) thought.

  18. Thinking or feeling? An exploratory study of maternal scaffolding, child mental state talk, and emotion understanding in language-impaired and typically developing school-aged children.

    Science.gov (United States)

    Yuill, Nicola; Little, Sarah

    2018-06-01

    Mother-child mental state talk (MST) supports children's developing social-emotional understanding. In typically developing (TD) children, family conversations about emotion, cognition, and causes have been linked to children's emotion understanding. Specific language impairment (SLI) may compromise developing emotion understanding and adjustment. We investigated emotion understanding in children with SLI and TD, in relation to mother-child conversation. Specifically, is cognitive, emotion, or causal MST more important for child emotion understanding and how might maternal scaffolding support this? Nine 5- to 9-year-old children with SLI and nine age-matched typically developing (TD) children, and their mothers. We assessed children's language, emotion understanding and reported behavioural adjustment. Mother-child conversations were coded for MST, including emotion, cognition, and causal talk, and for scaffolding of causal talk. Children with SLI scored lower than TD children on emotion understanding and adjustment. Mothers in each group provided similar amounts of cognitive, emotion, and causal talk, but SLI children used proportionally less cognitive and causal talk than TD children did, and more such child talk predicted better child emotion understanding. Child emotion talk did not differ between groups and did not predict emotion understanding. Both groups participated in maternal-scaffolded causal talk, but causal talk about emotion was more frequent in TD children, and such talk predicted higher emotion understanding. Cognitive and causal language scaffolded by mothers provides tools for articulating increasingly complex ideas about emotion, predicting children's emotion understanding. Our study provides a robust method for studying scaffolding processes for understanding causes of emotion. © 2017 The British Psychological Society.

  19. Technology as Teammate: Examining the Role of External Cognition in Support of Team Cognitive Processes.

    Science.gov (United States)

    Fiore, Stephen M; Wiltshire, Travis J

    2016-01-01

    In this paper we advance team theory by describing how cognition occurs across the distribution of members and the artifacts and technology that support their efforts. We draw from complementary theorizing coming out of cognitive engineering and cognitive science that views forms of cognition as external and extended and integrate this with theorizing on macrocognition in teams. Two frameworks are described that provide the groundwork for advancing theory and aid in the development of more precise measures for understanding team cognition via focus on artifacts and the technologies supporting their development and use. This includes distinctions between teamwork and taskwork and the notion of general and specific competencies from the organizational sciences along with the concepts of offloading and scaffolding from the cognitive sciences. This paper contributes to the team cognition literature along multiple lines. First, it aids theory development by synthesizing a broad set of perspectives on the varied forms of cognition emerging in complex collaborative contexts. Second, it supports research by providing diagnostic guidelines to study how artifacts are related to team cognition. Finally, it supports information systems designers by more precisely describing how to conceptualize team-supporting technology and artifacts. As such, it provides a means to more richly understand process and performance as it occurs within sociotechnical systems. Our overarching objective is to show how team cognition can both be more clearly conceptualized and more precisely measured by integrating theory from cognitive engineering and the cognitive and organizational sciences.

  20. Examining the Relationship Between Children's ADHD Symptomatology and Inadequate Parenting: The Role of Household Chaos.

    Science.gov (United States)

    Wirth, Andrea; Reinelt, Tilman; Gawrilow, Caterina; Schwenck, Christina; Freitag, Christine M; Rauch, Wolfgang A

    2017-02-01

    This study examines the interrelations of parenting practices, emotional climate, and household chaos in families with children with and without ADHD. In particular, indirect pathways from children's ADHD symptomatology to inadequate parenting and negative emotional climate via household chaos were investigated. Parenting, emotional climate, and household chaos were assessed using questionnaires and a speech sample of parents of 31 children with and 53 without ADHD, aged 7 to 13 years. Group differences were found for certain parenting dimensions, the parent-child relationship, critical comments, and household chaos. While we found significant indirect effects between children's ADHD and certain parenting dimensions through household chaos, no effects were found for any aspect of emotional climate. Children's ADHD symptoms translate into inadequate parenting through household chaos, which underlines the need for interventions to improve household organization skills in parents of children with ADHD.

  1. Role of Sex and the Environment in Moderating Weight Gain Due to Inadequate Sleep.

    Science.gov (United States)

    Coborn, Jamie E; Houser, Monica M; Perez-Leighton, Claudio E; Teske, Jennifer A

    2017-12-01

    The growing prevalence of obesity, inadequate sleep and sleep disorders together with the negative impact of lack of sleep on overall health highlights the need for therapies targeted towards weight gain due to sleep loss. Sex disparities in obesity and sleep disorders are present; yet, the role of sex is inadequately addressed and thus it is unclear whether sensitivity to sleep disruption differs between men and women. Like sex, environmental factors contribute to the development of obesity and poor sleep. The obesogenic environment is characterized by easy access to palatable foods and a low demand for energy expenditure in daily activities. These and other environmental factors are discussed, as they drive altered sleep or their interaction with food choice and intake can promote obesity. We discuss data that suggest differences in sleep patterns and responses to sleep disruption influence sex disparities in weight gain, and that enviromental disturbances alter sleep and interact with features of the obesogenic environment that together promote obesity.

  2. Sixth Graders' Co-Construction of Explanations of a Disturbance in an Ecosystem: Exploring Relationships between Grouping, Reflective Scaffolding, and Evidence-Based Explanations

    Science.gov (United States)

    Kyza, Eleni A.; Constantinou, Costas P.; Spanoudis, George

    2011-01-01

    We report on a study investigating the relationship between cognitive ability grouping, reflective inquiry scaffolding, and students' collaborative explanations of an ecosystem disturbance which took place when a number of flamingo birds died in a salt lake because of nearby intensive human activities. Twenty-six pairs of students from two intact…

  3. Inadequate management of pregnancy-associated listeriosis: lessons from four case reports.

    Science.gov (United States)

    Charlier, C; Goffinet, F; Azria, E; Leclercq, A; Lecuit, M

    2014-03-01

    Listeria monocytogenes infection during pregnancy can lead to dramatic fetal or neonatal outcomes. No clinical trial has evaluated treatment options, and retrospective studies of cases are therefore important to define optimal regimens. We report four cases of materno-neonatal listeriosis illustrating inadequate antimicrobial therapy management and discuss recommended treatment options. © 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.

  4. OCCUPATIONAL ACCIDENTS AS INDICATORS OF INADEQUATE WORK CONDITIONS AND WORK ENVIRONMENT

    OpenAIRE

    Petar Babović

    2009-01-01

    Occupational accidents due to inadequate working conditions and work environment present a major problem in highly industrialised countries, as well as in developing ones. Occupational accidents are a regular and accompanying phenomenon in all human activities and one of the main health related and economic problems in modern societies.The aim of this study is the analysis of the connections of unfavourable working conditions and working environment on occupational accidents. Occurrence of oc...

  5. Factors associated with inadequate work ability among women in the clothing industry.

    Science.gov (United States)

    Augusto, Viviane Gontijo; Sampaio, Rosana Ferreira; Ferreira, Fabiane Ribeiro; Kirkwood, Renata Noce; César, Cibele Comini

    2015-01-01

    Work ability depends on a balance between individual resources and work demands. This study evaluated factors that are associated with inadequate work ability among workers in the clothing industry. We conducted a cross-sectional observational study of 306 workers in 40 small and medium-sized enterprises. We assessed work ability, individual resources, physical and psychosocial demands, and aspects of life outside work using a binary logistic regression model with hierarchical data entry. The mean work ability was 42.5 (SD=3.5); when adjusted for age, only 11% of the workers showed inadequate work ability. The final model revealed that smoking, high isometric physical load, and poor physical environmental conditions were the most significant predictors of inadequate work ability. Good working conditions and worker education must be implemented to eliminate factors that can be changed and that have a negative impact on work ability. These initiatives include anti-smoking measures, improved postures at work, and better physical environmental conditions.

  6. Inadequate pelvic radiographs: implications of not getting it right the first time.

    Science.gov (United States)

    Parker, S; Nagra, N S; Kulkarni, K; Pegrum, J; Barry, S; Hughes, R; Ghani, Y

    2017-09-01

    Introduction Pelvic radiography is a frequent investigation. European guidelines aim to ensure appropriate use and adequate quality. When initial images are inadequate, repeat radiographs are often required, which may have significant patient safety and economic implications. Objectives The study aimed to assess the adequacy of pelvic imaging across three orthopaedic centres, to identify causes for inadequate imaging and to establish the cost of inadequate imaging from financial and patient safety perspectives. Methods Pelvic radiographs were identified on Picture Archiving and Communication System software at three UK hospitals. Radiographs were assessed against European guidelines and indications for repeat imaging were analysed. Results A total of 1,531 sequential pelvic radiographs were reviewed. The mean age of patients was 60 years (range 5 months to 101 years). Of this total, 51.9% of images were suboptimal, with no significant difference across the three hospitals (P > 0.05). Hospital 3 repeated radiographs in 6.3% of cases, compare with 18.1% and 19.7% at hospitals 1 and 2, respectively (P > 0.05). Hospital 3 identified pathology missed on the initial radiograph in 1% of cases, compared with 5.4% and 5.5% at hospitals 1 and 2, respectively (P > 0.05). Out-of-hours imaging is associated with a higher rate of suboptimal quality (69.1%) compared with normal working hours (51.3%; P = 0.006). Adequacy rates vary with age (χ 2 = 43.62, P hours imaging.

  7. Managing inadequate responses to frontline treatment of chronic myeloid leukemia: a case-based review.

    Science.gov (United States)

    Bixby, Dale L

    2013-05-01

    The tyrosine kinase inhibitors (TKIs) imatinib, nilotinib, and dasatinib are the standard of care for treating patients with newly diagnosed chronic-phase chronic myeloid leukemia (CML). Compared with interferon-based treatment, the previous standard of care, imatinib is associated with significantly higher cytogenetic response rates and prolonged overall survival. Nilotinib and dasatinib, both newer and more potent TKIs, significantly improve cytogenetic and molecular response rates compared with imatinib. Despite significant advances in CML treatment enabled by the TKIs, a fraction of patients who receive frontline treatment with a TKI demonstrate inadequate response. The reasons for this vary, but in many cases, inadequate response can be attributed to non-adherence to the treatment regimen, intolerance to the drug, intrinsic or acquired resistance to the drug, or a combination of reasons. More often than not, strategies to improve response necessitate a change in treatment plan, either a dose adjustment or a switch to an alternate drug, particularly in the case of drug intolerance or drug resistance. Improved physician-patient communication and patient education are effective strategies to address issues relating to adherence and intolerance. Because inadequate response to TKI treatment correlates with poor long-term outcomes, it is imperative that patients who experience intolerance or who fail to achieve appropriate responses are carefully evaluated so that appropriate treatment modifications can be made to maximize the likelihood of positive long-term outcome. Copyright © 2012. Published by Elsevier Ltd.

  8. Fluorescent composite scaffolds made of nanodiamonds/polycaprolactone

    Science.gov (United States)

    Cao, Li; Hou, Yanwen; Lafdi, Khalid; Urmey, Kirk

    2015-11-01

    Polycaprolactone (PCL) has been widely studied for biological applications. Biodegradable PCL fibrous scaffold can work as an appropriate substrate for tissue regeneration. In this letter, fluorescent nanodiamonds (FNDs) were prepared after surface passivation with octadecylamine. The FNDs were then mixed with PCL polymer and subsequently electrospun into FNDs/PCL fibrous scaffolds. The obtained scaffolds not only exhibited photoluminescence, but also showed reinforced mechanical strength. Toxicity study indicated FNDs/PCL scaffolds were nontoxic. This biocompatible fluorescent composite fibrous scaffold can support in vitro cell growth and also has the potential to act as an optical probe for tissue engineering application in vitro and in vivo.

  9. "Scaffolding" through Talk in Groupwork Learning

    Science.gov (United States)

    Panselinas, Giorgos; Komis, Vassilis

    2009-01-01

    In the present study, we develop and deploy a conceptual framework of "scaffolding" in groupwork learning, through the analysis of the pursuit of a learning goal over time. The analysis follows individuals' different experiences of an interaction as well as collective experiences, considering individual attainment as a result of a bi-directional…

  10. Acellular organ scaffolds for tumor tissue engineering

    Science.gov (United States)

    Guller, Anna; Trusova, Inna; Petersen, Elena; Shekhter, Anatoly; Kurkov, Alexander; Qian, Yi; Zvyagin, Andrei

    2015-12-01

    Rationale: Tissue engineering (TE) is an emerging alternative approach to create models of human malignant tumors for experimental oncology, personalized medicine and drug discovery studies. Being the bottom-up strategy, TE provides an opportunity to control and explore the role of every component of the model system, including cellular populations, supportive scaffolds and signalling molecules. Objectives: As an initial step to create a new ex vivo TE model of cancer, we optimized protocols to obtain organ-specific acellular matrices and evaluated their potential as TE scaffolds for culture of normal and tumor cells. Methods and results: Effective decellularization of animals' kidneys, ureter, lungs, heart, and liver has been achieved by detergent-based processing. The obtained scaffolds demonstrated biocompatibility and growthsupporting potential in combination with normal (Vero, MDCK) and tumor cell lines (C26, B16). Acellular scaffolds and TE constructs have been characterized and compared with morphological methods. Conclusions: The proposed methodology allows creation of sustainable 3D tumor TE constructs to explore the role of organ-specific cell-matrix interaction in tumorigenesis.

  11. Teacher Scaffolding of Oral Language Production

    Science.gov (United States)

    George, May G.

    2011-01-01

    This research involved two observational studies. It explored the scaffolding processes as part of classroom pedagogy. The research shed light on the way a teacher's instructional methodology took shape in the classroom. The target event for this study was the time in which a novice learner was engaged publicly in uttering a sentence in Arabic in…

  12. Membrane supported scaffold architectures for tissue engineering

    NARCIS (Netherlands)

    Bettahalli Narasimha, M.S.

    2011-01-01

    Tissue engineering aims at restoring or regenerating a damaged tissue. Often the tissue recreation occurs by combining cells, derived from a patient biopsy, onto a 3D porous matrix, functioning as a scaffold. One of the current limitations of tissue engineering is the inability to provide sufficient

  13. Communication Scaffolds for Project Management in PBL

    Science.gov (United States)

    Sasaki, Shigeru; Arai, Masayuki; Takai, Kumiko; Ogawa, Mitsuhiro; Watanabe, Hiroyoshi

    2017-01-01

    In this study, the role-playing situation and the system requirement list are adopted into project-based learning classes to develop web applications. In the classes, the third-year undergraduate project managers communicate with the client of the project rolled by teachers on the Web bulletin board. These are expected to act as scaffolds to…

  14. Polylactic acid organogel as versatile scaffolding technique

    NARCIS (Netherlands)

    Punet, Xavier; Levato, Riccardo; Bataille, Isabelle; Letourneur, Didier; Engel, Elisabeth; Mateos-Timoneda, Miguel A

    2017-01-01

    Tissue engineering requires scaffolding techniques based on non-toxic processes that permits the fabrication of constructs with tailored properties. Here, a two-step methodology based on the gelation and precipitation of the poly(lactic) acid/ethyl lactate organogel system is presented. With this

  15. Comparison of TALEN scaffolds in Xenopus tropicalis

    Directory of Open Access Journals (Sweden)

    Keisuke Nakajima

    2013-11-01

    Transcription activator-like effector nucleases (TALENs are facile and potent tools used to modify a gene of interest for targeted gene knockout. TALENs consist of an N-terminal domain, a DNA-binding domain, and a C-terminal domain, which are derived from a transcription activator-like effector, and the non-specific nuclease domain of FokI. Using Xenopus tropicalis (X. tropicalis, we compared the toxicities and somatic mutation activities of four TALEN architectures in a side-by-side manner: a basic TALEN, a scaffold with the same truncated N- and C-terminal domains as GoldyTALEN, a scaffold with the truncated N- and C-terminal domains and an obligate heterodimeric nuclease domain, and a scaffold with the truncated N- and C-terminal domains and an obligate heterodimeric Sharkey nuclease domain. The strongest phenotype and targeted somatic gene mutation were induced by the injection of TALEN mRNAs containing the truncated N- and C-terminal domains and an obligate heterodimeric nuclease domain. The obligate heterodimeric TALENs exhibited reduced toxicity compared to the homodimeric TALENs, and the homodimeric GoldyTALEN-type scaffold showed both a high activity of somatic gene modification and high toxicity. The Sharkey mutation in the heterodimeric nuclease domain reduced the TALEN-mediated somatic mutagenesis.

  16. Enhancing Student Learning through Scaffolded Client Projects

    Science.gov (United States)

    Tomlinson, Elizabeth

    2017-01-01

    This article reports on the current status of client projects (CPs) in business communication courses, provides a scaffolded model for implementing CP, and assesses student learning in CPs. Using a longitudinal mixed method research design, survey data and qualitative materials from six semesters are presented. The instructor survey indicated need…

  17. Muscle fragments on a scaffold in rats

    DEFF Research Database (Denmark)

    Jangö, Hanna; Gräs, Søren; Christensen, Lise

    2015-01-01

    -PLGA scaffolds seeded with autologous MFF affected some histological and biomechanical properties of native tissue repair in an abdominal wall defect model in rats. The method thus appears to be a simple tissue engineering concept with potential relevance for native tissue repair of POP....

  18. Biodegradable elastomeric scaffolds for soft tissue engineering

    NARCIS (Netherlands)

    Pêgo, A.P.; Poot, Andreas A.; Grijpma, Dirk W.; Feijen, Jan

    2003-01-01

    Elastomeric copolymers of 1,3-trimethylene carbonate (TMC) and ε-caprolactone (CL) and copolymers of TMC and D,L-lactide (DLLA) have been evaluated as candidate materials for the preparation of biodegradable scaffolds for soft tissue engineering. TMC-DLLA copolymers are amorphous and degrade more

  19. Peer scaffolding in an EFL writing classroom: An investigation of writing accuracy and scaffolding behaviors

    Directory of Open Access Journals (Sweden)

    Parastou Gholami Pasand

    2017-09-01

    Full Text Available Considering the tenets of Sociocultural Theory with its emphasis on co-construction of knowledge, L2 writing can be regarded as a co-writing practice whereby assistance is provided to struggling writers. To date, most studies have dealt with peer scaffolding in the revision phase of writing, as such planning and drafting are remained untouched. The present study examines the impact of peer scaffolding on writing accuracy of a group of intermediate EFL learners, and explores scaffolding behaviors employed by them in planning and drafting phases of writing. To these ends, 40 freshmen majoring in English Language and Literature in the University of Guilan were randomly divided into a control group and an experimental group consisting of dyads in which a competent writer provided scaffolding to a less competent one using the process approach to writing. Results of independent samples t-tests revealed that learners in the experimental group produced more accurate essays. Microgenetic analysis of one dyad’s talks showed that scaffolding behaviors used in planning and drafting phases of writing were more or less the same as those identified in the revision phase. These findings can be used to inform peer intervention in L2 writing classes, and assist L2 learners in conducting successful peer scaffolding in the planning and drafting phases of writing.

  20. Fabrication and Mechanical Characterization of Hydrogel Infused Network Silk Scaffolds

    Directory of Open Access Journals (Sweden)

    Lakshminath Kundanati

    2016-09-01

    Full Text Available Development and characterization of porous scaffolds for tissue engineering and regenerative medicine is of great importance. In recent times, silk scaffolds were developed and successfully tested in tissue engineering and drug release applications. We developed a novel composite scaffold by mechanical infusion of silk hydrogel matrix into a highly porous network silk scaffold. The mechanical behaviour of these scaffolds was thoroughly examined for their possible use in load bearing applications. Firstly, unconfined compression experiments show that the denser composite scaffolds displayed significant enhancement in the elastic modulus as compared to either of the components. This effect was examined and further explained with the help of foam mechanics principles. Secondly, results from confined compression experiments that resemble loading of cartilage in confinement, showed nonlinear material responses for all scaffolds. Finally, the confined creep experiments were performed to calculate the hydraulic permeability of the scaffolds using soil mechanics principles. Our results show that composite scaffolds with some modifications can be a potential candidate for use of cartilage like applications. We hope such approaches help in developing novel scaffolds for tissue engineering by providing an understanding of the mechanics and can further be used to develop graded scaffolds by targeted infusion in specific regions.

  1. Preparation of bioactive porous HA/PCL composite scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J.; Guo, L.Y.; Yang, X.B. [Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Weng, J. [Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China)], E-mail: jweng@swjtu.cn

    2008-12-30

    Porous hydroxyapatite (HA) bioceramic scaffold has been widely attracted the attention to act as a three-dimensional (3D) template for cell adhesion, proliferation, differentiation and thus promoting bone and cartilage regeneration because of its osteoinduction. However, the porous bioceramic scaffold is fragile so that it is not suitable to be applied in clinic for bone repair or replacement. Therefore, it is significant to improve the mechanical property of porous HA bioceramics while the interconnected structure is maintained for tissue ingrowth in vivo. In the present research, a porous composite scaffold composed of HA scaffold and polycaprolactone (PCL) lining was fabricated by the method of polymer impregnating to produce HA scaffold coated with PCL lining. Subsequently, the composite scaffolds were deposited with biomimetic coating for improving the bioactivity. The HA/PCL composite scaffolds with improved mechanical property and bioactivity is expected to be a promising bone substitute in tissue engineering applications.

  2. Scaffold diversification enhances effectiveness of a superlibrary of hyperthermophilic proteins.

    Science.gov (United States)

    Hussain, Mahmud; Gera, Nimish; Hill, Andrew B; Rao, Balaji M

    2013-01-18

    The use of binding proteins from non-immunoglobulin scaffolds has become increasingly common in biotechnology and medicine. Typically, binders are isolated from a combinatorial library generated by mutating a single scaffold protein. In contrast, here we generated a "superlibrary" or "library-of-libraries" of 4 × 10(8) protein variants by mutagenesis of seven different hyperthermophilic proteins; six of the seven proteins have not been used as scaffolds prior to this study. Binding proteins for five different model targets were successfully isolated from this library. Binders obtained were derived from five out of the seven scaffolds. Strikingly, binders from this modestly sized superlibrary have affinities comparable or higher than those obtained from a library with 1000-fold higher sequence diversity but derived from a single stable scaffold. Thus scaffold diversification, i.e., randomization of multiple different scaffolds, is a powerful alternate strategy for combinatorial library construction.

  3. Polyelectrolyte-complex nanostructured fibrous scaffolds for tissue engineering

    International Nuclear Information System (INIS)

    Verma, Devendra; Katti, Kalpana S.; Katti, Dinesh R.

    2009-01-01

    In the current work, polyelectrolyte complex (PEC) fibrous scaffolds for tissue engineering have been synthesized and a mechanism of their formation has been investigated. The scaffolds are synthesized using polygalacturonic acid and chitosan using the freeze drying methodology. Highly interconnected pores of sizes in the range of 5-20 μm are observed in the scaffolds. The thickness of the fibers was found to be in the range of 1-2 μm. Individual fibers have a nanogranular structure as observed using AFM imaging. In these scaffolds, PEC nanoparticles assemble together at the interface of ice crystals during freeze drying process. Further investigation shows that the freezing temperature and concentration have a remarkable effect on structure of scaffolds. Biocompatibility studies show that scaffold containing chitosan, polygalacturonic acid and hydroxyapatite promotes cell adhesion and proliferation. On the other hand, cells on scaffolds fabricated without hydroxyapatite nanoparticles showed poor adhesion.

  4. Synergistic Effect of Carbon Nanotubes and Graphene on Diopside Scaffolds.

    Science.gov (United States)

    Liu, Tingting; Wu, Ping; Gao, Chengde; Feng, Pei; Xiao, Tao; Deng, Youwen; Shuai, Cijun; Peng, Shuping

    2016-01-01

    A synergetic effect between carbon nanotubes (CNTs) and graphene on diopside (Di) scaffolds was demonstrated. 3D network architecture in the matrix was formed through the 1D CNTs inlaid among the 2D graphene platelets (GNPs). The mechanical properties of the CNTs/GNPs/Di scaffolds were significantly improved compared with the CNTs/Di scaffolds and GNPs/Di scaffolds. In addition, the scaffolds exhibited excellent apatite-forming ability, a modest degradation rate, and stable mechanical properties in simulated body fluid (SBF). Moreover, cell culturing tests indicated that the scaffolds supported the cells attachment and proliferation. Taken together, the CNTs/GNPs/Di scaffolds offered great potential for bone tissue engineering.

  5. Preparation of bioactive porous HA/PCL composite scaffolds

    International Nuclear Information System (INIS)

    Zhao, J.; Guo, L.Y.; Yang, X.B.; Weng, J.

    2008-01-01

    Porous hydroxyapatite (HA) bioceramic scaffold has been widely attracted the attention to act as a three-dimensional (3D) template for cell adhesion, proliferation, differentiation and thus promoting bone and cartilage regeneration because of its osteoinduction. However, the porous bioceramic scaffold is fragile so that it is not suitable to be applied in clinic for bone repair or replacement. Therefore, it is significant to improve the mechanical property of porous HA bioceramics while the interconnected structure is maintained for tissue ingrowth in vivo. In the present research, a porous composite scaffold composed of HA scaffold and polycaprolactone (PCL) lining was fabricated by the method of polymer impregnating to produce HA scaffold coated with PCL lining. Subsequently, the composite scaffolds were deposited with biomimetic coating for improving the bioactivity. The HA/PCL composite scaffolds with improved mechanical property and bioactivity is expected to be a promising bone substitute in tissue engineering applications

  6. Novel aza-analogous ergoline derived scaffolds as potent serotonin 5-HT6 and dopamine D2 receptor ligands

    DEFF Research Database (Denmark)

    Krogsgaard-Larsen, Niels; Jensen, Anders A.; Schrøder, T.J.

    2014-01-01

    By introducing distal substituents on a tetracyclic scaffold resembling the ergoline structure, two series of analogues were achieved exhibiting subnanomolar receptor binding affinities for the dopamine D2 and serotonin 5-HT6 receptor subtype, respectively. While the 5-HT6 ligands were antagonists......, the D2 ligands displayed intrinsic activities ranging from full agonism to partial agonism with low intrinsic activity. These structures could potentially be interesting for treatment of neurological diseases such as schizophrenia, Parkinson’s disease, and cognitive deficits....

  7. Cultural affordances: Scaffolding local worlds through shared intentionality and regimes of attention

    Directory of Open Access Journals (Sweden)

    Maxwell James D. Ramstead

    2016-07-01

    Full Text Available In this paper we outline a framework for the study of the mechanisms involved in the engagement of human agents with cultural affordances. Our aim is to better understand how culture and context interact with human biology to shape human behavior, cognition, and experience. We attempt to integrate several related approaches in the study of the embodied, cognitive, and affective substrates of sociality and culture and the sociocultural scaffolding of experience. The integrative framework we propose bridges cognitive and social sciences to provide (i an expanded concept of ‘affordance’ that extends to sociocultural forms of life, and (ii a multilevel account of the socioculturally scaffolded forms of affordance learning and the transmission of affordances in patterned sociocultural practices and regimes of shared attention. This framework provides an account of how cultural content and normative practices are built on a foundation of contentless basic mental processes that acquire content through immersive participation of the agent in social practices that regulate joint attention and shared intentionality.

  8. Use of Interim Scaffolding and Neotissue Development to Produce a Scaffold-Free Living Hyaline Cartilage Graft.

    Science.gov (United States)

    Lau, Ting Ting; Leong, Wenyan; Peck, Yvonne; Su, Kai; Wang, Dong-An

    2015-01-01

    The fabrication of three-dimensional (3D) constructs relies heavily on the use of biomaterial-based scaffolds. These are required as mechanical supports as well as to translate two-dimensional cultures to 3D cultures for clinical applications. Regardless of the choice of scaffold, timely degradation of scaffolds is difficult to achieve and undegraded scaffold material can lead to interference in further tissue development or morphogenesis. In cartilage tissue engineering, hydrogel is the highly preferred scaffold material as it shares many similar characteristics with native cartilaginous matrix. Hence, we employed gelatin microspheres as porogens to create a microcavitary alginate hydrogel as an interim scaffold to facilitate initial chondrocyte 3D culture and to establish a final scaffold-free living hyaline cartilaginous graft (LhCG) for cartilage tissue engineering.

  9. Materializing Mind: The Role of Objects in Cognition and Culture

    DEFF Research Database (Denmark)

    Tylén, Kristian; McGraw, John J.

    2014-01-01

    , and distributed cognition, we review and classify a set of cognitive processes mediated by material representations. Specifically, we ask how—in a range of everyday cognitive and cultural practices—we employ objects (1) to scaffold memory, (2) to alter cognitive complexity, (3) to facilitate epistemic......If mind is investigated as the set of interactions that accomplish a cognitive task, that is, if mind is more than that which occurs inside the head, then how does the interplay of biological and environmental resources produce human cognition? Informed by active externalism, joint action...... experimentation, (4) to enable the division of cognitive labor, (5) to promote confidence and trust, (6) to consolidate social structure, and (7) to support dialogical coupling. We conclude that through cultural practices the stable, “manipulable”, and public properties of objects have come to afford...

  10. Improving access to shared decision-making for Hispanics/Latinos with inadequately controlled type 2 diabetes mellitus.

    Science.gov (United States)

    Davidson, Jaime A; Rosales, Aracely; Shillington, Alicia C; Bailey, Robert A; Kabir, Chris; Umpierrez, Guillermo E

    2015-01-01

    To describe the cultural and linguistic adaptation and Spanish translation of an English-language patient decision aid (PDA) for use in supporting shared decision-making in Hispanics/Latinos with type 2 diabetes mellitus (T2DM), a group at a high risk for complications. A steering committee of endocrinologists, a primary care physician, a certified diabetes educator, and a dietician, each with extensive experience in providing care to Hispanics/Latinos was convened to assess a PDA developed for English-speaking patients with T2DM. English content was reviewed for cultural sensitivity and appropriateness for a Hispanic/Latino population. A consensus-building process and iterative version edits incorporated clinician perspectives. The content was adapted to be consistent with traditional Hispanic/Latino cultural communication precepts (eg, avoidance of hostile confrontation; value for warm interaction; respect for authority; value of family support for decisions). The PDA was translated by native-speaking individuals with diabetes expertise. The PDA underwent testing during cognitive interviews with ten Spanish-speaking Hispanics/Latinos with T2DM to ensure that the content is reflective of the experience, understanding, and language Hispanic/Latino patients use to describe diabetes and treatment. Content edits were made to assure a literacy level appropriate to the audience, and the PDA was produced for online video dissemination. High-quality, well-developed tools to facilitate shared decision-making in populations with limited access to culturally sensitive information can narrow gaps and align care with individual patient preferences. A newly developed PDA is available for shared decision-making that provides culturally appropriate treatment information for inadequately controlled Hispanics/Latinos with T2DM. The impact on the overall health of patients and care management of T2DM requires further study.

  11. Polycaprolactone nanofiber interspersed collagen type-I scaffold for bone regeneration: a unique injectable osteogenic scaffold

    International Nuclear Information System (INIS)

    Baylan, Nuray; Ditto, Maggie; Lawrence, Joseph G; Yildirim-Ayan, Eda; Bhat, Samerna; Lecka-Czernik, Beata

    2013-01-01

    There is an increasing demand for an injectable cell coupled three-dimensional (3D) scaffold to be used as bone fracture augmentation material. To address this demand, a novel injectable osteogenic scaffold called PN-COL was developed using cells, a natural polymer (collagen type-I), and a synthetic polymer (polycaprolactone (PCL)). The injectable nanofibrous PN-COL is created by interspersing PCL nanofibers within pre-osteoblast cell embedded collagen type-I. This simple yet novel and powerful approach provides a great benefit as an injectable bone scaffold over other non-living bone fracture stabilization polymers, such as polymethylmethacrylate and calcium content resin-based materials. The advantages of injectability and the biomimicry of collagen was coupled with the structural support of PCL nanofibers, to create cell encapsulated injectable 3D bone scaffolds with intricate porous internal architecture and high osteoconductivity. The effects of PCL nanofiber inclusion within the cell encapsulated collagen matrix has been evaluated for scaffold size retention and osteocompatibility, as well as for MC3T3-E1 cells osteogenic activity. The structural analysis of novel bioactive material proved that the material is chemically stable enough in an aqueous solution for an extended period of time without using crosslinking reagents, but it is also viscous enough to be injected through a syringe needle. Data from long-term in vitro proliferation and differentiation data suggests that novel PN-COL scaffolds promote the osteoblast proliferation, phenotype expression, and formation of mineralized matrix. This study demonstrates for the first time the feasibility of creating a structurally competent, injectable, cell embedded bone tissue scaffold. Furthermore, the results demonstrate the advantages of mimicking the hierarchical architecture of native bone with nano- and micro-size formation through introducing PCL nanofibers within macron-size collagen fibers and in

  12. Magnitude and determinants of inadequate third-trimester weight gain in rural Bangladesh

    Science.gov (United States)

    Hasan, S. M. Tafsir; Rahman, Sabuktagin; Locks, Lindsey Mina; Rahman, Mizanur; Hore, Samar Kumar; Saqeeb, Kazi Nazmus; Khan, Md. Alfazal

    2018-01-01

    Objectives The objective of this study was to estimate the magnitude and determinants of inadequate weight gain in the third-trimester among rural women in Matlab, Bangladesh. Methods The study analyzed data on weight gain in the third trimester in 1,883 pregnant women in Matlab, Bangladesh. All these women were admitted to Matlab hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b) for childbirth during 2012–2014, and they had singleton live births at term. Data were retrieved from the electronic databases of Matlab Health and Demographic Surveillance System and Matlab hospital. A multivariable logistic regression for inadequate weight gain in the third trimester (≤4 kg) was built with sociodemographic, environmental and maternal factors as predictors. Results One thousand and twenty-six (54%) pregnant women had inadequate weight gain in the third trimester. In the multivariable model, short stature turned out to be the most robust risk factor for inadequate weight gain in the third trimester (OR = 2.5; 95% CI 1.8, 3.5 for short compared to tall women). Pre-third-trimester BMI was inversely associated with insufficient weight gain (OR = 0.96; 95% CI 0.93, 0.99 for 1 unit increase in BMI). Other risk factors for inadequate weight gain in the third trimester were advanced age (OR = 1.9; 95% CI 1.2, 3.1 for ≥35 years compared to ≤19 years), parity (OR = 1.5; 95% CI 1.2, 1.9 for multipara compared to nulliparous women), low socioeconomic status (OR = 1.7; 95% CI 1.2, 2.3 for women in the lowest compared to women in the highest wealth quintile), low level of education (OR = 1.6; 95% CI 1.2, 2.1 for ≤5 years compared to ≥10 years of education), belonging to the Hindu religious community (OR = 1.8; 95% CI 1.3, 2.5), consuming arsenic-contaminated water (OR = 1.4; 95% CI 1.1, 1.9), and conceiving during monsoon or dry season compared to summer (OR = 1.4; 95% CI 1.1, 1.8). Conclusions Among rural Bangladeshi women in Matlab

  13. Scaffold of Selenium Nanovectors and Honey Phytochemicals for Inhibition of Pseudomonas aeruginosa Quorum Sensing and Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Prateeksha

    2017-03-01

    Full Text Available Honey is an excellent source of polyphenolic compounds that are effective in attenuating quorum sensing (QS, a chemical process of cell-to-cell communication system used by the opportunistic pathogen Pseudomonas aeruginosa to regulate virulence and biofilm formation. However, lower water solubility and inadequate bioavailability remains major concerns of these therapeutic polyphenols. Its therapeutic index can be improved by using nano-carrier systems to target QS signaling potently. In the present study, we fabricated a unique drug delivery system comprising selenium nanoparticles (SeNPs; non-viral vectors and polyphenols of honey (HP for enhancement of anti-QS activity of HP against P. aeruginosa PAO1. The developed selenium nano-scaffold showed superior anti-QS activity, anti-biofilm efficacy, and anti-virulence potential in both in-vitro and in-vivo over its individual components, SeNPs and HP. LasR is inhibited by selenium nano-scaffold in-vitro. Using computational molecular docking studies, we have also demonstrated that the anti-virulence activity of selenium nano-scaffold is reliant on molecular binding that occurs between HP and the QS receptor LasR through hydrogen bonding and hydrophobic interactions. Our preliminary investigations with selenium-based nano-carriers hold significant promise to improve anti-virulence effectiveness of phytochemicals by enhancing effective intracellular delivery.

  14. Inadequate emergence after anesthesia: emergence delirium and hypoactive emergence in the Postanesthesia Care Unit.

    Science.gov (United States)

    Xará, Daniela; Silva, Acácio; Mendonça, Júlia; Abelha, Fernando

    2013-09-01

    To evaluate the frequency, determinants, and outcome of inadequate emergence after elective surgery in the Postanesthesia Care Unit (PACU). Prospective observational study. 12-bed PACU of a tertiary-care hospital in a major metropolitan area. 266 adult patients admitted to the PACU. To evaluate inadequate emergence, the Richmond Agitation and Sedation Scale (RASS) was administered to patients 10 minutes after their admission to the PACU. Demographic data, perioperative variables, and postoperative length of stay (LOS) in the PACU and the hospital were recorded. 40 (15%) patients showed symptoms of inadequate emergence: 17 patients (6.4%) screened positive for emergence delirium and 23 patients (8.6%) showed hypoactive emergence. Determinants of emergence delirium were longer duration of preoperative fasting (P = 0.001), higher visual analog scale (VAS) scores for pain (P = 0.002), and major surgical risk (P = 0.001); these patients had a higher frequency of postoperative delirium (P = 0.017) and had higher nausea VAS score 6 hours after surgery (P = 0.001). Determinants of hypoactive emergence were duration of surgery (P = 0.003), amount of crystalloids administered during surgery (P = 0.002), residual neuromuscular block (P < 0.001), high-risk surgery (P = 0.002), and lower core temperature on PACU admission (P = 0.028); these patients also had more frequent residual neuromuscular block (P < 0.001) postoperative delirium (P < 0.001), and more frequent adverse respiratory events (P = 0.02). Patients with hypoactive emergence had longer PACU and hospital LOS. Preventable determinants for emergence delirium were higher postoperative pain scores and longer fasting times. Hypoactive emergence was associated with longer postoperative PACU and hospital LOSs. © 2013 Elsevier Inc. All rights reserved.

  15. Effect of inadequate ferrule segment location on fracture resistance of endodontically treated teeth

    Directory of Open Access Journals (Sweden)

    Satheesh B Haralur

    2018-01-01

    Full Text Available Introduction: The circumferential 2 mm ferrule during the fabrication of the crown is strongly advocated for the long-term clinical success. During the routine clinical practice, the dentist encounters the endodontically treated tooth (ETT with inadequacy of the ferrule in some segment due to caries, abrasion, and erosions. The aim of this in vitro study was to investigate the consequence of inadequate segmental ferrule location on fracture strength of the root canal-treated anterior and posterior teeth. Materials and Methods: Fifty each maxillary canine and mandibular premolar intact human teeth were root canal treated and sectioned at 2 mm above the cementum-enamel junction. The teeth samples were divided into 5 groups of 10 each. The G-I and G-V samples had the 360° ferrule and complete absence of the ferrule, respectively. The G-II had the inadequate ferrule on the palatal surface, while G-III and G-IV had inadequate ferrule at buccal and proximal area. Teeth samples were subsequently restored with glass-reinforced fiber post, composite core, and full veneer metal crown. The samples were tested with universal testing machine under static load to record the fracture resistance. The acquired data were subjected to ANOVA and Tukey's post hoc statistical analysis. Results: The G-I with circumferential ferrule showed the higher fracture resistance. The teeth samples with lack of the ferrule had the least fracture resistance. Among the segmental absence of ferrule, teeth samples with lack of the proximal ferrule were least affected. Deficiency of a ferrule on the lingual wall significantly affected the fracture strength in both anterior and posterior ETT. Conclusions: The ETT with sectional inadequacy of the ferrule is significantly more effective in resisting the fracture in comparison to the complete absence of the ferrule.

  16. Psychological distress is associated with inadequate dietary intake in Vietnamese marriage immigrant women in Korea.

    Science.gov (United States)

    Hwang, Ji-Yun; Lee, Sang Eun; Kim, Sun Hye; Chung, Hye Won; Kim, Wha Young

    2010-05-01

    Previous studies have reported that the nutritional status of Vietnamese female marriage immigrants in Korea is inadequate. And the mediation of acculturation stress can contribute to problems in their eating practices and dietary intakes. This study examines an association between psychological distress and inadequate dietary intake in Vietnamese female marriage immigrants living in Korea. A cross-sectional study analyzed baseline data (n=570) from the Cohort of Intermarried Women in Korea. Daily nutrient intakes were compared according to the quartiles of distress scores assessed by the Psychological Well-Being Index-Short Form. One-way analysis of variance and chi(2) tests were used to compare eating practices and nutrient intake across quartiles of psychological distress. Subjects in the highest stress scores were more likely to skip breakfast and to change their dietary habits after living in Korea than those in groups with low stress scores. Analyses of the subjects' Mini Dietary Assessments revealed that those with the highest stress scores were less likely to consume milk or dairy products, eat regular meals, or have balanced diets than those with the lowest stress scores. Nutrient intakes were found to be inadequate in the subjects, and those with the highest stress scores showed lower consumptions of energy, carbohydrate, protein, fat, calcium, zinc, thiamin, riboflavin, and folate compared to those with the lowest scores. The prevalence of underweight (body mass index [calculated as kg/m(2)] Korea was negatively associated with dietary intake. These findings can assist dietetics practitioners working with minority immigrants because such information is important in designing appropriate strategies for dietary counseling. A follow-up study should address the underlying mechanisms of the observed diet-distress association in Vietnamese marriage immigrant women in Korea, as well as other various ethnic minority immigrants in Korea. Copyright 2010 American

  17. Cognitive functioning in adolescents with migraine

    Directory of Open Access Journals (Sweden)

    Melissa Andréia Costa-Silva

    Full Text Available Although migraine is highly prevalent in children and teenagers, it often goes undetected in these patients, resulting in underdiagnosis and inadequate treatment. Several studies have investigated cognitive changes in adults with migraine. However, there are few studies focusing on children and adolescents. Objective : To investigate cognitive performance of adolescents with migraine. Methods : Twenty-eight adolescents diagnosed with migraine and twenty-six individuals without a history of headache were recruited for the study. All participants were evaluated using standardized neuropsychological tests. Results : Adolescents with migraine had worse performance on tests evaluating short- and long-term verbal memory, attention, executive function, and speed of processing information than controls. Conclusion : Cognitive dysfunction is common in adolescents with migraine. Since the cognitive deficits found in adolescents with migraine are similar to those reported in adults with migraine, cognitive impairment seems to persist throughout life.

  18. Improving the Effectiveness of Speaker Verification Domain Adaptation With Inadequate In-Domain Data

    Science.gov (United States)

    2017-08-20

    M speakers. We seek a probabilistic solution to domain adap- tation, and so we encode knowledge of the out-of-domain data in prior distributions...the VB solution from (16)-(21) becomes: µ =αȳ + (1− α)µout, (24) Σa =α ( 1 NT NT∑ n=1 〈ynyTn 〉 − ȳȳT ) + (1− α) Σouta (25) + α (1− α) ( ȳ − µout...non- English languages and from unseen channels. An inadequate in-domain set was provided, which consisted of 2272 samples from 1164 speakers, and

  19. Magnetic responsive hydroxyapatite composite scaffolds construction for bone defect reparation.

    Science.gov (United States)

    Zeng, Xiao Bo; Hu, Hao; Xie, Li Qin; Lan, Fang; Jiang, Wen; Wu, Yao; Gu, Zhong Wei

    2012-01-01

    In recent years, interest in magnetic biomimetic scaffolds for tissue engineering has increased considerably. A type of magnetic scaffold composed of magnetic nanoparticles (MNPs) and hydroxyapatite (HA) for bone repair has been developed by our research group. In this study, to investigate the influence of the MNP content (in the scaffolds) on the cell behaviors and the interactions between the magnetic scaffold and the exterior magnetic field, a series of MNP-HA magnetic scaffolds with different MNP contents (from 0.2% to 2%) were fabricated by immersing HA scaffold into MNP colloid. ROS 17/2.8 and MC3T3-E1 cells were cultured on the scaffolds in vitro, with and without an exterior magnetic field, respectively. The cell adhesion, proliferation and differentiation were evaluated via scanning electron microscopy; confocal laser scanning microscopy; and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), alkaline phosphatase, and bone gla protein activity tests. The results demonstrated the positive influence of the magnetic scaffolds on cell adhesion, proliferation, and differentiation. Further, a higher amount of MNPs on the magnetic scaffolds led to more significant stimulation. The magnetic scaffold can respond to the exterior magnetic field and engender some synergistic effect to intensify the stimulating effect of a magnetic field to the proliferation and differentiation of cells.

  20. 3D Printing of Scaffolds for Tissue Regeneration Applications

    Science.gov (United States)

    Do, Anh-Vu; Khorsand, Behnoush; Geary, Sean M.; Salem, Aliasger K.

    2015-01-01

    The current need for organ and tissue replacement, repair and regeneration for patients is continually growing such that supply is not meeting the high demand primarily due to a paucity of donors as well as biocompatibility issues that lead to immune rejection of the transplant. In an effort to overcome these drawbacks, scientists working in the field of tissue engineering and regenerative medicine have investigated the use of scaffolds as an alternative to transplantation. These scaffolds are designed to mimic the extracellular matrix (ECM) by providing structural support as well as promoting attachment, proliferation, and differentiation with the ultimate goal of yielding functional tissues or organs. Initial attempts at developing scaffolds were problematic and subsequently inspired a growing interest in 3D printing as a mode for generating scaffolds. Utilizing three-dimensional printing (3DP) technologies, ECM-like scaffolds can be produced with a high degree of complexity and precision, where fine details can be included at a micron level. In this review, we discuss the criteria for printing viable and functional scaffolds, scaffolding materials, and 3DP technologies used to print scaffolds for tissue engineering. A hybrid approach, employing both natural and synthetic materials, as well as multiple printing processes may be the key to yielding an ECM-like scaffold with high mechanical strength, porosity, interconnectivity, biocompatibility, biodegradability, and high processability. Creating such biofunctional scaffolds could potentially help to meet the demand by patients for tissues and organs without having to wait or rely on donors for transplantation. PMID:26097108

  1. Surface modified electrospun nanofibrous scaffolds for nerve tissue engineering

    International Nuclear Information System (INIS)

    Prabhakaran, Molamma P; Venugopal, J; Chan, Casey K; Ramakrishna, S

    2008-01-01

    The development of biodegradable polymeric scaffolds with surface properties that dominate interactions between the material and biological environment is of great interest in biomedical applications. In this regard, poly-ε-caprolactone (PCL) nanofibrous scaffolds were fabricated by an electrospinning process and surface modified by a simple plasma treatment process for enhancing the Schwann cell adhesion, proliferation and interactions with nanofibers necessary for nerve tissue formation. The hydrophilicity of surface modified PCL nanofibrous scaffolds (p-PCL) was evaluated by contact angle and x-ray photoelectron spectroscopy studies. Naturally derived polymers such as collagen are frequently used for the fabrication of biocomposite PCL/collagen scaffolds, though the feasibility of procuring large amounts of natural materials for clinical applications remains a concern, along with their cost and mechanical stability. The proliferation of Schwann cells on p-PCL nanofibrous scaffolds showed a 17% increase in cell proliferation compared to those on PCL/collagen nanofibrous scaffolds after 8 days of cell culture. Schwann cells were found to attach and proliferate on surface modified PCL nanofibrous scaffolds expressing bipolar elongations, retaining their normal morphology. The results of our study showed that plasma treated PCL nanofibrous scaffolds are a cost-effective material compared to PCL/collagen scaffolds, and can potentially serve as an ideal tissue engineered scaffold, especially for peripheral nerve regeneration.

  2. A Review on Fabricating Tissue Scaffolds using Vat Photopolymerization.

    Science.gov (United States)

    Chartrain, Nicholas A; Williams, Christopher B; Whittington, Abby R

    2018-05-09

    Vat Photopolymerization (stereolithography, SLA), an Additive Manufacturing (AM) or 3D printing technology, holds particular promise for the fabrication of tissue scaffolds for use in regenerative medicine. Unlike traditional tissue scaffold fabrication techniques, SLA is capable of fabricating designed scaffolds through the selective photopolymerization of a photopolymer resin on the micron scale. SLA offers unprecedented control over scaffold porosity and permeability, as well as pore size, shape, and interconnectivity. Perhaps even more significantly, SLA can be used to fabricate vascular networks that may encourage angio and vasculogenesis. Fulfilling this potential requires the development of new photopolymers, the incorporation of biochemical factors into printed scaffolds, and an understanding of the effects scaffold geometry have on cell viability, proliferation, and differentiation. This review compares SLA to other scaffold fabrication techniques, highlights significant advances in the field, and offers a perspective on the field's challenges and future directions. Engineering de novo tissues continues to be challenging due, in part, to our inability to fabricate complex tissue scaffolds that can support cell proliferation and encourage the formation of developed tissue. The goal of this review is to first introduce the reader to traditional and Additive Manufacturing scaffold fabrication techniques. The bulk of this review will then focus on apprising the reader of current research and provide a perspective on the promising use of vat photopolymerization (stereolithography, SLA) for the fabrication of complex tissue scaffolds. Copyright © 2018. Published by Elsevier Ltd.

  3. Image-based characterization of foamed polymeric tissue scaffolds

    International Nuclear Information System (INIS)

    Mather, Melissa L; Morgan, Stephen P; Crowe, John A; White, Lisa J; Shakesheff, Kevin M; Tai, Hongyun; Howdle, Steven M; Kockenberger, Walter

    2008-01-01

    Tissue scaffolds are integral to many regenerative medicine therapies, providing suitable environments for tissue regeneration. In order to assess their suitability, methods to routinely and reproducibly characterize scaffolds are needed. Scaffold structures are typically complex, and thus their characterization is far from trivial. The work presented in this paper is centred on the application of the principles of scaffold characterization outlined in guidelines developed by ASTM International. Specifically, this work demonstrates the capabilities of different imaging modalities and analysis techniques used to characterize scaffolds fabricated from poly(lactic-co-glycolic acid) using supercritical carbon dioxide. Three structurally different scaffolds were used. The scaffolds were imaged using: scanning electron microscopy, micro x-ray computed tomography, magnetic resonance imaging and terahertz pulsed imaging. In each case two-dimensional images were obtained from which scaffold properties were determined using image processing. The findings of this work highlight how the chosen imaging modality and image-processing technique can influence the results of scaffold characterization. It is concluded that in order to obtain useful results from image-based scaffold characterization, an imaging methodology providing sufficient contrast and resolution must be used along with robust image segmentation methods to allow intercomparison of results

  4. Restoring nervous system structure and function using tissue engineered living scaffolds

    Directory of Open Access Journals (Sweden)

    Laura A Struzyna

    2015-01-01

    Full Text Available Neural tissue engineering is premised on the integration of engineered living tissue with the host nervous system to directly restore lost function or to augment regenerative capacity following nervous system injury or neurodegenerative disease. Disconnection of axon pathways - the long-distance fibers connecting specialized regions of the central nervous system or relaying peripheral signals - is a common feature of many neurological disorders and injury. However, functional axonal regeneration rarely occurs due to extreme distances to targets, absence of directed guidance, and the presence of inhibitory factors in the central nervous system, resulting in devastating effects on cognitive and sensorimotor function. To address this need, we are pursuing multiple strategies using tissue engineered "living scaffolds", which are preformed three-dimensional constructs consisting of living neural cells in a defined, often anisotropic architecture. Living scaffolds are designed to restore function by serving as a living labeled pathway for targeted axonal regeneration - mimicking key developmental mechanisms- or by restoring lost neural circuitry via direct replacement of neurons and axonal tracts. We are currently utilizing preformed living scaffolds consisting of neuronal clusters spanned by long axonal tracts as regenerative bridges to facilitate long-distance axonal regeneration and for targeted neurosurgical reconstruction of local circuits in the brain. Although there are formidable challenges in preclinical and clinical advancement, these living tissue engineered constructs represent a promising strategy to facilitate nervous system repair and functional recovery.

  5. ASTM International Workshop on Standards & Measurements for Tissue Engineering Scaffolds

    Science.gov (United States)

    Simon, Carl G.; Yaszemski, Michael J.; Ratcliffe, Anthony; Tomlins, Paul; Luginbuehl, Reto; Tesk, John A.

    2016-01-01

    The “Workshop on Standards & Measurements for Tissue Engineering Scaffolds” was held on May 21, 2013 in Indianapolis, IN and was sponsored by the ASTM International (ASTM). The purpose of the workshop was to identify the highest priority items for future standards work for scaffolds used in the development and manufacture of tissue engineered medical products (TEMPs). Eighteen speakers and 78 attendees met to assess current scaffold standards and to prioritize needs for future standards. A key finding was that the ASTM TEMPs subcommittees (F04.41-46) have many active “guide” documents for educational purposes, but that few standard “test methods” or “practices” have been published. Overwhelmingly, the most clearly identified need was standards for measuring the structure of scaffolds, followed by standards for biological characterization, including in vitro testing, animal models and cell-material interactions. The third most pressing need was to develop standards for assessing the mechanical properties of scaffolds. Additional needs included standards for assessing scaffold degradation, clinical outcomes with scaffolds, effects of sterilization on scaffolds, scaffold composition and drug release from scaffolds. Discussions also highlighted the need for additional scaffold reference materials and the need to use them for measurement traceability. Finally, dialogue emphasized the needs to promote the use of standards in scaffold fabrication, characterization, and commercialization and to assess the use and impact of standards in the TEMPs community. Many scaffold standard needs have been identified and focus should now turn to generating these standards to support the use of scaffolds in TEMPs. PMID:25220952

  6. A radiopaque electrospun scaffold for engineering fibrous musculoskeletal tissues: Scaffold characterization and in vivo applications.

    Science.gov (United States)

    Martin, John T; Milby, Andrew H; Ikuta, Kensuke; Poudel, Subash; Pfeifer, Christian G; Elliott, Dawn M; Smith, Harvey E; Mauck, Robert L

    2015-10-01

    Tissue engineering strategies have emerged in response to the growing prevalence of chronic musculoskeletal conditions, with many of these regenerative methods currently being evaluated in translational animal models. Engineered replacements for fibrous tissues such as the meniscus, annulus fibrosus, tendons, and ligaments are subjected to challenging physiologic loads, and are difficult to track in vivo using standard techniques. The diagnosis and treatment of musculoskeletal conditions depends heavily on radiographic assessment, and a number of currently available implants utilize radiopaque markers to facilitate in vivo imaging. In this study, we developed a nanofibrous scaffold in which individual fibers included radiopaque nanoparticles. Inclusion of radiopaque particles increased the tensile modulus of the scaffold and imparted radiation attenuation within the range of cortical bone. When scaffolds were seeded with bovine mesenchymal stem cells in vitro, there was no change in cell proliferation and no evidence of promiscuous conversion to an osteogenic phenotype. Scaffolds were implanted ex vivo in a model of a meniscal tear in a bovine joint and in vivo in a model of total disc replacement in the rat coccygeal spine (tail), and were visualized via fluoroscopy and microcomputed tomography. In the disc replacement model, histological analysis at 4 weeks showed that the scaffold was biocompatible and supported the deposition of fibrous tissue in vivo. Nanofibrous scaffolds that include radiopaque nanoparticles provide a biocompatible template with sufficient radiopacity for in vivo visualization in both small and large animal models. This radiopacity may facilitate image-guided implantation and non-invasive long-term evaluation of scaffold location and performance. The healing capacity of fibrous musculoskeletal tissues is limited, and injury or degeneration of these tissues compromises the standard of living of millions in the US. Tissue engineering repair

  7. The design of 3D scaffold for tissue engineering using automated scaffold design algorithm.

    Science.gov (United States)

    Mahmoud, Shahenda; Eldeib, Ayman; Samy, Sherif

    2015-06-01

    Several progresses have been introduced in the field of bone regenerative medicine. A new term tissue engineering (TE) was created. In TE, a highly porous artificial extracellular matrix or scaffold is required to accommodate cells and guide their growth in three dimensions. The design of scaffolds with desirable internal and external structure represents a challenge for TE. In this paper, we introduce a new method known as automated scaffold design (ASD) for designing a 3D scaffold with a minimum mismatches for its geometrical parameters. The method makes use of k-means clustering algorithm to separate the different tissues and hence decodes the defected bone portions. The segmented portions of different slices are registered to construct the 3D volume for the data. It also uses an isosurface rendering technique for 3D visualization of the scaffold and bones. It provides the ability to visualize the transplanted as well as the normal bone portions. The proposed system proves good performance in both the segmentation results and visualizations aspects.

  8. Dynamic Scaffolding of Socially Regulated Learning in a Computer-Based Learning Environment

    Science.gov (United States)

    Molenaar, Inge; Roda, Claudia; van Boxtel, Carla; Sleegers, Peter

    2012-01-01

    The aim of this study is to test the effects of dynamically scaffolding social regulation of middle school students working in a computer-based learning environment. Dyads in the scaffolding condition (N=56) are supported with computer-generated scaffolds and students in the control condition (N=54) do not receive scaffolds. The scaffolds are…

  9. Protein Scaffolding for Small Molecule Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Baker, David [Univ. of Washington, Seattle, WA (United States)

    2014-09-14

    We aim to design hybrid catalysts for energy production and storage that combine the high specificity, affinity, and tunability of proteins with the potent chemical reactivities of small organometallic molecules. The widely used Rosetta and RosettaDesign methodologies will be extended to model novel protein / small molecule catalysts in which one or many small molecule active centers are supported and coordinated by protein scaffolding. The promise of such hybrid molecular systems will be demonstrated with the nickel-phosphine hydrogenase of DuBois et. al.We will enhance the hydrogenase activity of the catalyst by designing protein scaffolds that incorporate proton relays and systematically modulate the local environment of the catalyticcenter. In collaboration with DuBois and Shaw, the designs will be experimentally synthesized and characterized.

  10. Diamond as a scaffold for bone growth.

    Science.gov (United States)

    Fox, Kate; Palamara, Joseph; Judge, Roy; Greentree, Andrew D

    2013-04-01

    Diamond is an attractive material for biomedical implants. In this work, we investigate its capacity as a bone scaffold. It is well established that the bioactivity of a material can be evaluated by examining its capacity to form apatite-like calcium phosphate phases on its surface when exposed to simulated body fluid. Accordingly, polycrystalline diamond (PCD) and ultrananocrystalline diamond (UNCD) deposited by microwave plasma chemical vapour deposition were exposed to simulated body fluid and assessed for apatite growth when compared to the bulk silicon. Scanning electron microscopy and X-ray photoelectron spectroscopy showed that both UNCD and PCD are capable of acting as a bone scaffold. The composition of deposited apatite suggests that UNCD and PCD are suitable for in vivo implantation with UNCD possible favoured in applications where rapid osseointegration is essential.

  11. Optimized Diazo Scaffold for Protein Esterification

    Science.gov (United States)

    Mix, Kalie A.

    2015-01-01

    The O-alkylation of carboxylic acids with diazo compounds provides a means to esterify carboxylic acids in aqueous solution. A Hammett analysis of the reactivity of diazo compounds derived from phenylglycinamide revealed that the p-methylphenylglycinamide scaffold has an especially high reaction rate and ester:alcohol product ratio, and esterifies protein carboxyl groups more efficiently than does any known reagent. PMID:25938936

  12. In Vitro Degradation of PHBV Scaffolds and nHA/PHBV Composite Scaffolds Containing Hydroxyapatite Nanoparticles for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Naznin Sultana

    2012-01-01

    Full Text Available This paper investigated the long-term in vitro degradation properties of scaffolds based on biodegradable polymers and osteoconductive bioceramic/polymer composite materials for the application of bone tissue engineering. The three-dimensional porous scaffolds were fabricated using emulsion-freezing/freeze-drying technique using poly(hydroxybutyrate-co-hydroxyvalerate (PHBV which is a natural biodegradable and biocompatible polymer. Nanosized hydroxyapatite (nHA particles were successfully incorporated into the PHBV scaffolds to render the scaffolds osteoconductive. The PHBV and nHA/PHBV scaffolds were systematically evaluated using various techniques in terms of mechanical strength, porosity, porous morphology, and in vitro degradation. PHBV and nHA/PHBV scaffolds degraded over time in phosphate-buffered saline at 37°C. PHBV polymer scaffolds exhibited slow molecular weight loss and weight loss in the in vitro physiological environment. Accelerated weight loss was observed in nHA incorporated PHBV composite scaffolds. An increasing trend of crystallinity was observed during the initial period of degradation time. The compressive properties decreased more than 40% after 5-month in vitro degradation. Together with interconnected pores, high porosity, suitable mechanical properties, and slow degradation profile obtained from long-term degradation studies, the PHBV scaffolds and osteoconductive nHA/PHBV composite scaffolds showed promises for bone tissue engineering application.

  13. Soy Protein Scaffold Biomaterials for Tissue Engineering and Regenerative Medicine

    Science.gov (United States)

    Chien, Karen B.

    Developing functional biomaterials using highly processable materials with tailorable physical and bioactive properties is an ongoing challenge in tissue engineering. Soy protein is an abundant, natural resource with potential use for regenerative medicine applications. Preliminary studies show that soy protein can be physically modified and fabricated into various biocompatible constructs. However, optimized soy protein structures for tissue regeneration (i.e. 3D porous scaffolds) have not yet been designed. Furthermore, little work has established the in vivo biocompatibility of implanted soy protein and the benefit of using soy over other proteins including FDA-approved bovine collagen. In this work, freeze-drying and 3D printing fabrication processes were developed using commercially available soy protein to create porous scaffolds that improve cell growth and infiltration compared to other soy biomaterials previously reported. Characterization of scaffold structure, porosity, and mechanical/degradation properties was performed. In addition, the behavior of human mesenchymal stem cells seeded on various designed soy scaffolds was analyzed. Biological characterization of the cell-seeded scaffolds was performed to assess feasibility for use in liver tissue regeneration. The acute and humoral response of soy scaffolds implanted in an in vivo mouse subcutaneous model was also investigated. All fabricated soy scaffolds were modified using thermal, chemical, and enzymatic crosslinking to change properties and cell growth behavior. 3D printing allowed for control of scaffold pore size and geometry. Scaffold structure, porosity, and degradation rate significantly altered the in vivo response. Freeze-dried soy scaffolds had similar biocompatibility as freeze-dried collagen scaffolds of the same protein content. However, the soy scaffolds degraded at a much faster rate, minimizing immunogenicity. Interestingly, subcutaneously implanted soy scaffolds affected blood

  14. Delayed ultraviolet light-induced cessation of respiration by inadequate aeration of Escherichia coli

    International Nuclear Information System (INIS)

    Joshi, J.G.; Swenson, P.A.; Schenley, R.L.

    1977-01-01

    Inadequately aerated Escherichia coli B/r cultures did not shut their respiration off 60 min after ultraviolet light (52 J/m 2 at 254 nm) as they did when well supplied with oxygen. Since cessation of respiration is associated with cell death, the result suggested that oxygen toxicity by superoxide radicals generated by cell metabolism might be responsible for cell death. The specific activity of superoxide dismutase, which scavenges O 2 - radicals, increased twofold after 90 min of adequate aeration, but the specific activity of catalase remained constant. Respiration and viability of irradiated cells were affected not at all by the presence of superoxide dismutase and only slightly by the presence of catalase. Metal ions such as Mn 2+ and Fe 2+ , inducers of superoxide dismutase, had no effect on respiration and viability. When irradiated cells were incubated under N 2 for 90 min, the respiration, growth, and viability time-course responses were the same as for cells not exposed to anaerobiosis. We conclude that superoxide anions generated at the time of irradiation play no part in cessation of respiration and cell death and that inadequate aeration or anaerobiosis delays the ultraviolet light-induced synthesis of proteins responsible for the irreversible cessation of respiration

  15. The relations between inadequate parent-child boundaries and borderline personality disorder in adolescence.

    Science.gov (United States)

    Vanwoerden, Salome; Kalpakci, Allison; Sharp, Carla

    2017-11-01

    Borderline Personality Disorder (BPD) is a severe mental illness that onsets in adolescence. Research has demonstrated the central role of parent-child relationships for the development and maintenance of BPD although more research is necessary to clarify the specific dynamics that relate to BPD during adolescence. Based on preliminary research establishing the importance of parent-child boundaries for adolescent BPD, this study sought to evaluate the relations between different forms of inadequate boundaries and BPD in adolescence using a multi-method approach. To that end, 301 adolescents (65.1% female; ages 12-17) inpatients were recruited; parents and adolescents completed questionnaire- and interview-based measures of BPD features in adolescent children and a questionnaire-based measure of parent-child boundaries. Relations were found between parental guilt induction and psychological control with children's BPD features above and beyond relations with psychiatric severity and gender. Relations between parent reports of triangulation (when children are recruited to mediate parental marital conflict) and children's BPD were contingent on the level of children's perceptions of triangulation. Findings confirm previous research suggesting the relevance of inadequate parent-child boundaries to children's BPD features and have important implications for understanding the dynamics in families with adolescents with BPD, representing a relevant treatment target. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. A test of the cerebellar hypothesis of dyslexia in adequate and inadequate responders to reading intervention.

    Science.gov (United States)

    Barth, Amy E; Denton, Carolyn A; Stuebing, Karla K; Fletcher, Jack M; Cirino, Paul T; Francis, David J; Vaughn, Sharon

    2010-05-01

    The cerebellar hypothesis of dyslexia posits that cerebellar deficits are associated with reading disabilities and may explain why some individuals with reading disabilities fail to respond to reading interventions. We tested these hypotheses in a sample of children who participated in a grade 1 reading intervention study (n = 174) and a group of typically achieving children (n = 62). At posttest, children were classified as adequately responding to the intervention (n = 82), inadequately responding with decoding and fluency deficits (n = 36), or inadequately responding with only fluency deficits (n = 56). Based on the Bead Threading and Postural Stability subtests from the Dyslexia Screening Test-Junior, we found little evidence that assessments of cerebellar functions were associated with academic performance or responder status. In addition, we did not find evidence supporting the hypothesis that cerebellar deficits are more prominent for poor readers with "specific" reading disabilities (i.e., with discrepancies relative to IQ) than for poor readers with reading scores consistent with IQ. In contrast, measures of phonological awareness, rapid naming, and vocabulary were strongly associated with responder status and academic outcomes. These results add to accumulating evidence that fails to associate cerebellar functions with reading difficulties.

  17. Inadequate Sleep and Exercise Associated with Burnout and Depression Among Medical Students.

    Science.gov (United States)

    Wolf, Megan R; Rosenstock, Jason B

    2017-04-01

    The authors studied whether low levels of exercise or inadequate sleep correlated with higher levels of burnout and depression in medical students. Medical students of all years at the University of Pittsburgh School of Medicine, Pittsburgh, PA, USA, were invited to participate in an anonymous online survey in Fall 2012 and Winter 2013. Validated measures were used to assess exercise, sleep, burnout, and depression. Response rates were 28.7 % at the beginning of the school year and 22.6 % at the middle of the school year. Burnout rates overall were 22.4 % at the beginning of the year and 19.2 % in the middle of the year. Eight percent of students screened positive for depression at the beginning of the year and 9.3 % in the middle of the year. Decreased exercise frequency was significantly correlated with lower professional efficacy. Pathological sleepiness was significantly associated with a higher prevalence of burnout. Inadequate sleep correlated with significantly lower professional efficacy and higher exhaustion scores. Burnout was associated with a positive depression screen. Positive depression screening, pathological sleepiness, and sleeping less than 7 h a night were independent predictors of burnout. Sleep habits, exercise, and a positive depression screen were associated with burnout risk within the medical student population.

  18. Inadequate ventilation for nosocomial tuberculosis prevention in public hospitals in Central Thailand.

    Science.gov (United States)

    Jiamjarasrangsi, W; Bualert, S; Chongthaleong, A; Chaindamporn, A; Udomsantisuk, N; Euasamarnjit, W

    2009-04-01

    Forty-two community and general hospitals in central Thailand. To examine the adequacy of indoor ventilation for nosocomial tuberculosis (TB) prevention in public hospitals in central Thailand. A cross-sectional survey was conducted among 323 patient care and ancillary areas in the target hospitals. Data on indoor ventilation rate were collected by the tracer gas method and reported as air changes per hour (ACH). The adequacy of the measured ventilation rates were then determined by comparison with the international recommended standard values. Indoor ventilation rates were inadequate in almost half of the studied areas (144/323, 44.6%). The inadequacy was particularly serious in the emergency rooms (ERs) and radiological areas, where 73.8% (31/42 each) of the rooms had ACH below the recommended standards. Detailed analysis showed that most of the rooms with natural ventilation had air exchange rates that exceeded the recommended standards, while the opposite was the case for rooms with air-conditioning, particularly the window or wall-mount type. Indoor ventilation in high-risk nosocomial TB areas in public hospitals in Thailand was inadequate due to the installation of air-conditioning systems in modern buildings.

  19. Nonoclusive thrombosis of mechanical mitral valve prosthesis caused by inadequate treatment of anticoagulant therapy resistance

    Directory of Open Access Journals (Sweden)

    Ivanović Branislava

    2008-01-01

    Full Text Available Background. Oral anticoagulants have been used in the prevention of thromboembolic complications for over six decades. A rare, but possible problem in the application of these medications could be resistance to them. Case report. We presented a patient with nonocclusive thrombosis of the mechanical mitral prosthesis due to inadequately treated resistance to peroral anticoagulant therapy. Resistance to oral anticoagulant medications was proven by an increased dosage of warfarin up to 20 mg and, after that, acenokumarol to 15 mg over ten days which did not lead to an increase in the international normalized ratio (INR value over 1.2. On the basis of information that she did not take food rich in vitamin K or medications which could reduce effects of oral anticoagulants, and that she did not have additional illnesses and conditions that could cause an inadequate response to anticoagulant therapy, it was circumstantially concluded that this was a hereditary form of resistance. Because of the existing mechanical prosthetics on the mitral position, low molecular heparin has been introduced into the therapy. The patient reduced it on her own initiative, leading to nonocclusive valvular thrombosis. Conclusion. When associated complications like absolute arrhithmia does not exist, the finding of resistance to oral anticoagulant agents is an indication for the replacement of a mechanical prosthetic with a biological one which has been done in this patients.

  20. Household Response to Inadequate Sewerage and Garbage Collection Services in Abuja, Nigeria.

    Science.gov (United States)

    Abubakar, Ismaila Rimi

    2017-01-01

    Provision of sanitation and garbage collection services is an important and yet challenging issue in the rapidly growing cities of developing countries, with significant human health and environmental sustainability implications. Although a growing number of studies have investigated the consequences of inadequate delivery of basic urban services in developing countries, few studies have examined how households cope with the problems. Using the Exit, Voice, Loyalty, and Neglect (EVLN) model, this article explores how households respond to inadequate sewerage and garbage collection services in Abuja, Nigeria. Based on a qualitative study, data were gathered from in-depth interviews with sixty households, complemented with personal observation. The findings from grounded analysis indicated that majority (62%) and about half (55%) of the respondents have utilized the informal sector for sewerage services and garbage collection, respectively, to supplement the services provided by the city. While 68% of the respondents reported investing their personal resources to improve the delivery of existing sewerage services, half (53%) have collectively complained to the utility agency and few (22%) have neglected the problems. The paper concludes by discussing the public health and environmental sustainability implications of the findings.

  1. Factors associated with an inadequate hypoglycemia in the insulin tolerance test in Japanese patients with suspected or proven hypopituitarism.

    Science.gov (United States)

    Takahashi, Kiyohiko; Nakamura, Akinobu; Miyoshi, Hideaki; Nomoto, Hiroshi; Kameda, Hiraku; Cho, Kyu Yong; Nagai, So; Shimizu, Chikara; Taguri, Masataka; Terauchi, Yasuo; Atsumi, Tatsuya

    2017-04-29

    We attempted to identify the predictors of an inadequate hypoglycemia in insulin tolerance test (ITT), defined as a blood glucose level higher than 2.8 mmol/L after insulin injection, in Japanese patients with suspected or proven hypopituitarism. A total of 78 patients who had undergone ITT were divided into adequate and inadequate hypoglycemia groups. The relationships between the subjects' clinical parameters and inadequate hypoglycemia in ITT were analyzed. Stepwise logistic regression analysis identified high systolic blood pressure (SBP) and high homeostasis model assessment of insulin resistance (HOMA-IR) as being independent factors associated with inadequate hypoglycemia in ITT. Receiver operating characteristic (ROC) curve analysis revealed the cutoff value for inadequate hypoglycemia was 109 mmHg for SBP and 1.4 for HOMA-IR. The areas under ROC curve for SBP and HOMA-IR were 0.72 and 0.86, respectively. We confirmed that high values of SBP and HOMA-IR were associated with inadequate hypoglycemia in ITT, regardless of the degree of reduction of pituitary hormone levels. Furthermore, the strongest predictor of inadequate hypoglycemia was obtained by using the cutoff value of HOMA-IR. Our results suggest that HOMA-IR is a useful pre-screening tool for ITT in these populations.

  2. Melt electrospinning of biodegradable polyurethane scaffolds

    Science.gov (United States)

    Karchin, Ari; Simonovsky, Felix I.; Ratner, Buddy D.; Sanders, Joan E.

    2014-01-01

    Electrospinning from the melt, in contrast to from solution, is an attractive tissue engineering scaffold manufacturing process as it allows for the formation of small diameter fibers while eliminating potentially cytotoxic solvents. Despite this, there is a dearth of literature on scaffold formation via melt electrospinning. This is likely due to the technical challenges related to the need for a well-controlled high temperature setup and the difficulty in developing an appropriate polymer. In this paper, a biodegradable and thermally stable polyurethane (PU) is described specifically for use in melt electrospinning. Polymer formulations of aliphatic PUs based on (CH2)4-content diisocyanates, polycaprolactone (PCL), 1,4-butanediamine and 1,4-butanediol (BD) were evaluated for utility in the melt electrospinning process. The final polymer formulation, a catalyst-purified PU based on 1,4-butane diisocyanate, PCL and BD in a 4/1/3 molar ratio with a weight-average molecular weight of about 40 kDa, yielded a nontoxic polymer that could be readily electrospun from the melt. Scaffolds electrospun from this polymer contained point bonds between fibers and mechanical properties analogous to many in vivo soft tissues. PMID:21640853

  3. Microfibrous silver-coated polymeric scaffolds with tunable mechanical properties

    KAUST Repository

    Kalakonda, Parvathalu.; Aldhahri, Musab A.; Abdel-wahab, Mohamed Shaaban; Tamayol, Ali; Moghaddam, K. Mollazadeh; Ben Rached, Fathia; Pain, Arnab; Khademhosseini, Ali; Memic, Adnan; Chaieb, Saharoui

    2017-01-01

    Electrospun scaffolds of poly(glycerol sebacate)/poly(ε-caprolactone) (PGS/PCL) have been used for engineered tissues due to their desirable thermal and mechanical properties as well as their tunable degradability. In this paper, we fabricated micro-fibrous scaffolds from a composite of PGS/PCL using a standard electrospinning method and coated them with silver (Ag). The low temperature coating method prevented substrate melting and the Ag coating decreases the pore size and increases the diameter of fibers which resulted in enhanced thermal and mechanical properties. We further compared the mechanical properties of the composite fibrous scaffolds with different thicknesses of Ag coated scaffolds. The composite fibrous scaffold with a 275 nm Ag coating showed higher tensile modulus (E) and ultimate tensile strength (UTS) without any post-processing treatment. Lastly, potential controlled release of the Ag coating from the composite fibrous scaffolds could present interesting biomedical applications.

  4. Microfibrous silver-coated polymeric scaffolds with tunable mechanical properties

    KAUST Repository

    Kalakonda, Parvathalu.

    2017-07-07

    Electrospun scaffolds of poly(glycerol sebacate)/poly(ε-caprolactone) (PGS/PCL) have been used for engineered tissues due to their desirable thermal and mechanical properties as well as their tunable degradability. In this paper, we fabricated micro-fibrous scaffolds from a composite of PGS/PCL using a standard electrospinning method and coated them with silver (Ag). The low temperature coating method prevented substrate melting and the Ag coating decreases the pore size and increases the diameter of fibers which resulted in enhanced thermal and mechanical properties. We further compared the mechanical properties of the composite fibrous scaffolds with different thicknesses of Ag coated scaffolds. The composite fibrous scaffold with a 275 nm Ag coating showed higher tensile modulus (E) and ultimate tensile strength (UTS) without any post-processing treatment. Lastly, potential controlled release of the Ag coating from the composite fibrous scaffolds could present interesting biomedical applications.

  5. Bioactive Nano-fibrous Scaffold for Vascularized Craniofacial Bone Regeneration

    DEFF Research Database (Denmark)

    Prabha, Rahul Damodaran; Kraft, David Christian Evar; Harkness, Linda

    2018-01-01

    the limitation of cell penetration of electrospun scaffolds and improve on its osteoconductive nature, in this study, we fabricated a novel electrospun composite scaffold of polyvinyl alcohol (PVA) - poly (ε) caprolactone (PCL) - Bioceramic (HAB), namely, PVA-PCL-HAB. The scaffold prepared by dual...... electrospinning of PVA and PCL with HAB overcomes reduced cell attachment associated with hydrophobic poly (ε) caprolactone (PCL) by combination with a hydrophilic polyvinyl alcohol (PVA) and the bioceramic (HAB) can contribute to enhance osteo-conductivity. We characterized the physicochemical...... and biocompatibility properties of the new scaffold material. Our results indicate PVA-PCL-HAB scaffolds support attachment and growth of stromal stem cells; (human bone marrow skeletal (mesenchymal) stem cells (hMSC) and dental pulp stem cells (DPSC)). In addition, the scaffold supported in vitro osteogenic...

  6. Porous magnesium-based scaffolds for tissue engineering

    International Nuclear Information System (INIS)

    Yazdimamaghani, Mostafa; Razavi, Mehdi; Vashaee, Daryoosh; Moharamzadeh, Keyvan; Boccaccini, Aldo R.; Tayebi, Lobat

    2017-01-01

    Significant amount of research efforts have been dedicated to the development of scaffolds for tissue engineering. Although at present most of the studies are focused on non-load bearing scaffolds, many scaffolds have also been investigated for hard tissue repair. In particular, metallic scaffolds are being studied for hard tissue engineering due to their suitable mechanical properties. Several biocompatible metallic materials such as stainless steels, cobalt alloys, titanium alloys, tantalum, nitinol and magnesium alloys have been commonly employed as implants in orthopedic and dental treatments. They are often used to replace and regenerate the damaged bones or to provide structural support for healing bone defects. Among the common metallic biomaterials, magnesium (Mg) and a number of its alloys are effective because of their mechanical properties close to those of human bone, their natural ionic content that may have important functional roles in physiological systems, and their in vivo biodegradation characteristics in body fluids. Due to such collective properties, Mg based alloys can be employed as biocompatible, bioactive, and biodegradable scaffolds for load-bearing applications. Recently, porous Mg and Mg alloys have been specially suggested as metallic scaffolds for bone tissue engineering. With further optimization of the fabrication techniques, porous Mg is expected to make a promising hard substitute scaffold. The present review covers research conducted on the fabrication techniques, surface modifications, properties and biological characteristics of Mg alloys based scaffolds. Furthermore, the potential applications, challenges and future trends of such degradable metallic scaffolds are discussed in detail. - Highlights: • A porous 3D material provides the required pathways for cells to grow, proliferate, and differentiate • Porous magnesium and Mg alloys could be used as load-bearing scaffolds • Porous magnesium and Mg alloys are good

  7. Porous magnesium-based scaffolds for tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Yazdimamaghani, Mostafa [School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States); Razavi, Mehdi [Department of Radiology, School of Medicine, Stanford University, Palo Alto, CA 94304 (United States); Vashaee, Daryoosh [Electrical and Computer Engineering Department, North Carolina State University, Raleigh, NC 27606 (United States); Moharamzadeh, Keyvan [School of Clinical Dentistry, University of Sheffield, Claremont Crescent, Sheffield (United Kingdom); Marquette University School of Dentistry, Milwaukee, WI 53233 (United States); Boccaccini, Aldo R. [Institute of Biomaterials, University of Erlangen-Nuremberg, Cauerstrasse 6, 91058 Erlangen (Germany); Tayebi, Lobat, E-mail: lobat.tayebi@marquette.edu [Marquette University School of Dentistry, Milwaukee, WI 53233 (United States)

    2017-02-01

    Significant amount of research efforts have been dedicated to the development of scaffolds for tissue engineering. Although at present most of the studies are focused on non-load bearing scaffolds, many scaffolds have also been investigated for hard tissue repair. In particular, metallic scaffolds are being studied for hard tissue engineering due to their suitable mechanical properties. Several biocompatible metallic materials such as stainless steels, cobalt alloys, titanium alloys, tantalum, nitinol and magnesium alloys have been commonly employed as implants in orthopedic and dental treatments. They are often used to replace and regenerate the damaged bones or to provide structural support for healing bone defects. Among the common metallic biomaterials, magnesium (Mg) and a number of its alloys are effective because of their mechanical properties close to those of human bone, their natural ionic content that may have important functional roles in physiological systems, and their in vivo biodegradation characteristics in body fluids. Due to such collective properties, Mg based alloys can be employed as biocompatible, bioactive, and biodegradable scaffolds for load-bearing applications. Recently, porous Mg and Mg alloys have been specially suggested as metallic scaffolds for bone tissue engineering. With further optimization of the fabrication techniques, porous Mg is expected to make a promising hard substitute scaffold. The present review covers research conducted on the fabrication techniques, surface modifications, properties and biological characteristics of Mg alloys based scaffolds. Furthermore, the potential applications, challenges and future trends of such degradable metallic scaffolds are discussed in detail. - Highlights: • A porous 3D material provides the required pathways for cells to grow, proliferate, and differentiate • Porous magnesium and Mg alloys could be used as load-bearing scaffolds • Porous magnesium and Mg alloys are good

  8. Dissecting Sequences of Regulation and Cognition: Statistical Discourse Analysis of Primary School Children's Collaborative Learning

    Science.gov (United States)

    Molenaar, Inge; Chiu, Ming Ming

    2014-01-01

    Extending past research showing that regulative activities (metacognitive and relational) can aid learning, this study tests whether sequences of cognitive, metacognitive and relational activities affect subsequent cognition. Scaffolded by a computer avatar, 54 primary school students (working in 18 groups of 3) discussed writing a report about a…

  9. Design and Usability Assessment of a Dialogue-Based Cognitive Tutoring System to Model Expert Problem Solving in Research Design

    Science.gov (United States)

    Hung, Wei-Chen; Smith, Thomas J.; Smith, M. Cecil

    2015-01-01

    Technology provides the means to create useful learning and practice environments for learners. Well-designed cognitive tutor systems, for example, can provide appropriate learning environments that feature cognitive supports (ie, scaffolding) for students to increase their procedural knowledge. The purpose of this study was to conduct a series of…

  10. Intrinsic Osteoinductivity of Porous Titanium Scaffold for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Maryam Tamaddon

    2017-01-01

    Full Text Available Large bone defects and nonunions are serious complications that are caused by extensive trauma or tumour. As traditional therapies fail to repair these critical-sized defects, tissue engineering scaffolds can be used to regenerate the damaged tissue. Highly porous titanium scaffolds, produced by selective laser sintering with mechanical properties in range of trabecular bone (compressive strength 35 MPa and modulus 73 MPa, can be used in these orthopaedic applications, if a stable mechanical fixation is provided. Hydroxyapatite coatings are generally considered essential and/or beneficial for bone formation; however, debonding of the coatings is one of the main concerns. We hypothesised that the titanium scaffolds have an intrinsic potential to induce bone formation without the need for a hydroxyapatite coating. In this paper, titanium scaffolds coated with hydroxyapatite using electrochemical method were fabricated and osteoinductivity of coated and noncoated scaffolds was compared in vitro. Alizarin Red quantification confirmed osteogenesis independent of coating. Bone formation and ingrowth into the titanium scaffolds were evaluated in sheep stifle joints. The examinations after 3 months revealed 70% bone ingrowth into the scaffold confirming its osteoinductive capacity. It is shown that the developed titanium scaffold has an intrinsic capacity for bone formation and is a suitable scaffold for bone tissue engineering.

  11. Multilayer porous UHMWPE scaffolds for bone defects replacement

    Energy Technology Data Exchange (ETDEWEB)

    Maksimkin, A.V. [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Senatov, F.S., E-mail: senatov@misis.ru [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Anisimova, N.Yu.; Kiselevskiy, M.V. [National University of Science and Technology “MISIS”, Moscow (Russian Federation); N.N. Blokhin Russian Cancer Research Center, Moscow (Russian Federation); Zalepugin, D.Yu.; Chernyshova, I.V.; Tilkunova, N.A. [State Plant of Medicinal Drugs, Moscow (Russian Federation); Kaloshkin, S.D. [National University of Science and Technology “MISIS”, Moscow (Russian Federation)

    2017-04-01

    Reconstruction of the structural integrity of the damaged bone tissue is an urgent problem. UHMWPE may be potentially used for the manufacture of porous implants simulating as closely as possible the porous cancellous bone tissue. But the extremely high molecular weight of the polymer does not allow using traditional methods of foaming. Porous and multilayer UHMWPE scaffolds with nonporous bulk layer and porous layer that mimics cancellous bone architecture were obtained by solid-state mixing, thermopressing and washing in subcritical water. Structural and mechanical properties of the samples were studied. Porous UHMWPE samples were also studied in vitro and in vivo. The pores of UHMWPE scaffold are open and interconnected. Volume porosity of the obtained samples was 79 ± 2%; the pore size range was 80–700 μm. Strong connection of the two layers in multilayer UHMWPE scaffolds was observed with decreased number of fusion defects. Functionality of implants based on multilayer UHMWPE scaffolds is provided by the fixation of scaffolds in the bone defect through ingrowths of the connective tissue into the pores, which ensures the maintenance of the animals' mobility - Highlights: • Porous UHMWPE scaffold mimics cancellous bone architecture, maintaining its flexibility. • Multilayer UHMWPE scaffold is able to simulate different types of bone tissue. • Fixation of scaffolds in the bone provides through ingrowths of the connective tissue into pores. • Multilayer UHMWPE scaffolds can be used for the formation of bone implants.

  12. Multilayer porous UHMWPE scaffolds for bone defects replacement

    International Nuclear Information System (INIS)

    Maksimkin, A.V.; Senatov, F.S.; Anisimova, N.Yu.; Kiselevskiy, M.V.; Zalepugin, D.Yu.; Chernyshova, I.V.; Tilkunova, N.A.; Kaloshkin, S.D.

    2017-01-01

    Reconstruction of the structural integrity of the damaged bone tissue is an urgent problem. UHMWPE may be potentially used for the manufacture of porous implants simulating as closely as possible the porous cancellous bone tissue. But the extremely high molecular weight of the polymer does not allow using traditional methods of foaming. Porous and multilayer UHMWPE scaffolds with nonporous bulk layer and porous layer that mimics cancellous bone architecture were obtained by solid-state mixing, thermopressing and washing in subcritical water. Structural and mechanical properties of the samples were studied. Porous UHMWPE samples were also studied in vitro and in vivo. The pores of UHMWPE scaffold are open and interconnected. Volume porosity of the obtained samples was 79 ± 2%; the pore size range was 80–700 μm. Strong connection of the two layers in multilayer UHMWPE scaffolds was observed with decreased number of fusion defects. Functionality of implants based on multilayer UHMWPE scaffolds is provided by the fixation of scaffolds in the bone defect through ingrowths of the connective tissue into the pores, which ensures the maintenance of the animals' mobility - Highlights: • Porous UHMWPE scaffold mimics cancellous bone architecture, maintaining its flexibility. • Multilayer UHMWPE scaffold is able to simulate different types of bone tissue. • Fixation of scaffolds in the bone provides through ingrowths of the connective tissue into pores. • Multilayer UHMWPE scaffolds can be used for the formation of bone implants.

  13. Biochemical properties of Hemigraphis alternata incorporated chitosan hydrogel scaffold.

    Science.gov (United States)

    Annapoorna, M; Sudheesh Kumar, P T; Lakshman, Lakshmi R; Lakshmanan, Vinoth-Kumar; Nair, Shantikumar V; Jayakumar, R

    2013-02-15

    In this work, Hemigraphis alternata extract incorporated chitosan scaffold was synthesized and characterized for wound healing. The antibacterial activity of Hemigraphis incorporated chitosan scaffold (HIC) against Escherichia coli and Staphylococcus aureus was evaluated which showed a reduction in total colony forming units by 45-folds toward E. coli and 25-fold against S. aureus respectively. Cell viability studies using Human Dermal Fibroblast cells (HDF) showed 90% viability even at 48 h when compared to the chitosan control. The herbal scaffold made from chitosan was highly haemostatic and antibacterial. The obtained results were in support that the herbal scaffold can be effectively applied for infectious wounds. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Low elastic modulus titanium–nickel scaffolds for bone implants

    International Nuclear Information System (INIS)

    Li, Jing; Yang, Hailin; Wang, Huifeng; Ruan, Jianming

    2014-01-01

    The superelastic nature of repeating the human bones is crucial to the ideal artificial biomedical implants to ensure smooth load transfer and foster the ingrowth of new bone tissues. Three dimensional interconnected porous TiNi scaffolds, which have the tailorable porous structures with micro-hole, were fabricated by slurry immersing with polymer sponge and sintering method. The crystallinity and phase composition of scaffolds were studied by X-ray diffraction. The pore morphology, size and distribution in the scaffolds were characterized by scanning electron microscopy. The porosity ranged from 65 to 72%, pore size was 250–500 μm. Compressive strength and elastic modulus of the scaffolds were ∼ 73 MPa and ∼ 3GPa respectively. The above pore structural and mechanical properties are similar to those of cancellous bone. In the initial cell culture test, osteoblasts adhered well to the scaffold surface during a short time, and then grew smoothly into the interconnected pore channels. These results indicate that the porous TiNi scaffolds fabricated by this method could be bone substitute materials. - Highlights: • A novel approach for the fabrication of porous TiNi scaffolds • Macroporous structures are replicated from the polymer sponge template. • The pore characteristics and mechanical properties of TiNi scaffolds agree well with the requirement of trabecular bone. • Cytocompatibility of TiNi scaffolds is assessed, and it closely associated with pore property

  15. [Strategies to choose scaffold materials for tissue engineering].

    Science.gov (United States)

    Gao, Qingdong; Zhu, Xulong; Xiang, Junxi; Lü, Yi; Li, Jianhui

    2016-02-01

    Current therapies of organ failure or a wide range of tissue defect are often not ideal. Transplantation is the only effective way for long time survival. But it is hard to meet huge patients demands because of donor shortage, immune rejection and other problems. Tissue engineering could be a potential option. Choosing a suitable scaffold material is an essential part of it. According to different sources, tissue engineering scaffold materials could be divided into three types which are natural and its modified materials, artificial and composite ones. The purpose of tissue engineering scaffold is to repair the tissues or organs damage, so could reach the ideal recovery in its function and structure aspect. Therefore, tissue engineering scaffold should even be as close as much to the original tissue or organs in function and structure. We call it "organic scaffold" and this strategy might be the drastic perfect substitute for the tissues or organs in concern. Optimized organization with each kind scaffold materials could make up for biomimetic structure and function of the tissue or organs. Scaffold material surface modification, optimized preparation procedure and cytosine sustained-release microsphere addition should be considered together. This strategy is expected to open new perspectives for tissue engineering. Multidisciplinary approach including material science, molecular biology, and engineering might find the most ideal tissue engineering scaffold. Using the strategy of drawing on each other strength and optimized organization with each kind scaffold material to prepare a multifunctional biomimetic tissue engineering scaffold might be a good method for choosing tissue engineering scaffold materials. Our research group had differentiated bone marrow mesenchymal stem cells into bile canaliculi like cells. We prepared poly(L-lactic acid)/poly(ε-caprolactone) biliary stent. The scaffold's internal played a part in the long-term release of cytokines which

  16. Novel biodegradable porous scaffold applied to skin regeneration.

    Science.gov (United States)

    Wang, Hui-Min; Chou, Yi-Ting; Wen, Zhi-Hong; Wang, Chau-Zen; Wang, Zhao-Ren; Chen, Chun-Hong; Ho, Mei-Ling

    2013-01-01

    Skin wound healing is an important lifesaving issue for massive lesions. A novel porous scaffold with collagen, hyaluronic acid and gelatin was developed for skin wound repair. The swelling ratio of this developed scaffold was assayed by water absorption capacity and showed a value of over 20 g water/g dried scaffold. The scaffold was then degraded in time- and dose-dependent manners by three enzymes: lysozyme, hyaluronidase and collagenase I. The average pore diameter of the scaffold was 132.5±8.4 µm measured from SEM images. With human skin cells growing for 7 days, the SEM images showed surface fractures on the scaffold due to enzymatic digestion, indicating the biodegradable properties of this scaffold. To simulate skin distribution, the human epidermal keratinocytes, melanocytes and dermal fibroblasts were seeded on the porous scaffold and the cross-section immunofluorescent staining demonstrated normal human skin layer distributions. The collagen amount was also quantified after skin cells seeding and presented an amount 50% higher than those seeded on culture wells. The in vivo histological results showed that the scaffold ameliorated wound healing, including decreasing neutrophil infiltrates and thickening newly generated skin compared to the group without treatments.

  17. Novel biodegradable porous scaffold applied to skin regeneration.

    Directory of Open Access Journals (Sweden)

    Hui-Min Wang

    Full Text Available Skin wound healing is an important lifesaving issue for massive lesions. A novel porous scaffold with collagen, hyaluronic acid and gelatin was developed for skin wound repair. The swelling ratio of this developed scaffold was assayed by water absorption capacity and showed a value of over 20 g water/g dried scaffold. The scaffold was then degraded in time- and dose-dependent manners by three enzymes: lysozyme, hyaluronidase and collagenase I. The average pore diameter of the scaffold was 132.5±8.4 µm measured from SEM images. With human skin cells growing for 7 days, the SEM images showed surface fractures on the scaffold due to enzymatic digestion, indicating the biodegradable properties of this scaffold. To simulate skin distribution, the human epidermal keratinocytes, melanocytes and dermal fibroblasts were seeded on the porous scaffold and the cross-section immunofluorescent staining demonstrated normal human skin layer distributions. The collagen amount was also quantified after skin cells seeding and presented an amount 50% higher than those seeded on culture wells. The in vivo histological results showed that the scaffold ameliorated wound healing, including decreasing neutrophil infiltrates and thickening newly generated skin compared to the group without treatments.

  18. Chitosan composite three dimensional macrospheric scaffolds for bone tissue engineering.

    Science.gov (United States)

    Vyas, Veena; Kaur, Tejinder; Thirugnanam, Arunachalam

    2017-11-01

    The present work deals with the fabrication of chitosan composite scaffolds with controllable and predictable internal architecture for bone tissue engineering. Chitosan (CS) based composites were developed by varying montmorillonite (MMT) and hydroxyapatite (HA) combinations to fabricate macrospheric three dimensional (3D) scaffolds by direct agglomeration of the sintered macrospheres. The fabricated CS, CS/MMT, CS/HA and CS/MMT/HA 3D scaffolds were characterized for their physicochemical, biological and mechanical properties. The XRD and ATR-FTIR studies confirmed the presence of the individual constituents and the molecular interaction between them, respectively. The reinforcement with HA and MMT showed reduced swelling and degradation rate. It was found that in comparison to pure CS, the CS/HA/MMT composites exhibited improved hemocompatibility and protein adsorption. The sintering of the macrospheres controlled the swelling ability of the scaffolds which played an important role in maintaining the mechanical strength of the 3D scaffolds. The CS/HA/MMT composite scaffold showed 14 folds increase in the compressive strength when compared to pure CS scaffolds. The fabricated scaffolds were also found to encourage the MG 63 cell proliferation. Hence, from the above studies it can be concluded that the CS/HA/MMT composite 3D macrospheric scaffolds have wider and more practical application in bone tissue regeneration applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Facile method of building hydroxyapatite 3D scaffolds assembled from porous hollow fibers enabling nutrient delivery

    NARCIS (Netherlands)

    Salamon, David; Da Silva Teixeira, Sandra; Dutczak, S.M.; Stamatialis, Dimitrios

    2014-01-01

    Nowadays, diffusion through scaffold and tissue usually limits transport, and forms potentially hypoxic regions. Several methods are used for preparation of 3D hydroxyapatite scaffolds, however, production of a scaffold including porous hollow fibers for nutrition delivery is difficult and

  20. Distributed Cognition and Distributed Morality: Agency, Artifacts and Systems.

    Science.gov (United States)

    Heersmink, Richard

    2017-04-01

    There are various philosophical approaches and theories describing the intimate relation people have to artifacts. In this paper, I explore the relation between two such theories, namely distributed cognition and distributed morality theory. I point out a number of similarities and differences in these views regarding the ontological status they attribute to artifacts and the larger systems they are part of. Having evaluated and compared these views, I continue by focussing on the way cognitive artifacts are used in moral practice. I specifically conceptualise how such artifacts (a) scaffold and extend moral reasoning and decision-making processes, (b) have a certain moral status which is contingent on their cognitive status, and (c) whether responsibility can be attributed to distributed systems. This paper is primarily written for those interested in the intersection of cognitive and moral theory as it relates to artifacts, but also for those independently interested in philosophical debates in extended and distributed cognition and ethics of (cognitive) technology.

  1. The cognitive functions of language.

    Science.gov (United States)

    Carruthers, Peter

    2002-12-01

    This paper explores a variety of different versions of the thesis that natural language is involved in human thinking. It distinguishes amongst strong and weak forms of this thesis, dismissing some as implausibly strong and others as uninterestingly weak. Strong forms dismissed include the view that language is conceptually necessary for thought (endorsed by many philosophers) and the view that language is de facto the medium of all human conceptual thinking (endorsed by many philosophers and social scientists). Weak forms include the view that language is necessary for the acquisition of many human concepts and the view that language can serve to scaffold human thought processes. The paper also discusses the thesis that language may be the medium of conscious propositional thinking, but argues that this cannot be its most fundamental cognitive role. The idea is then proposed that natural language is the medium for nondomain-specific thinking, serving to integrate the outputs of a variety of domain-specific conceptual faculties (or central-cognitive "quasimodules"). Recent experimental evidence in support of this idea is reviewed and the implications of the idea are discussed, especially for our conception of the architecture of human cognition. Finally, some further kinds of evidence which might serve to corroborate or refute the hypothesis are mentioned. The overall goal of the paper is to review a wide variety of accounts of the cognitive function of natural language, integrating a number of different kinds of evidence and theoretical consideration in order to propose and elaborate the most plausible candidate.

  2. 2013 Nutrition Risk Evidence Review Panel. Evidence Review for: The Risk Factor of Inadequate Nutrition

    Science.gov (United States)

    2014-01-01

    The 2013 Nutrition Risk Standing Review Panel (from here on referred to as the SRP) met for a site visit in Houston, TX on November 20 - 21, 2013. The SRP reviewed the new Evidence Report for the Risk Factor of Inadequate Nutrition (from here on referred to as the 2013 Nutrition Evidence Report), as well as the Research Plan for this Risk. Overall, the SRP thinks the well-qualified research team has compiled an excellent summary of background information in the 2013 Nutrition Evidence Report. The SRP would like to commend the authors in general and particularly note that while the 2013 Nutrition Evidence Report has been written using a single nutrient approach, the research plan takes a much more integrated and physiologically based approach.

  3. Follow-up of abnormal or inadequate test results in the Danish Cervical Cancer Screening Program

    DEFF Research Database (Denmark)

    Kristiansen, Bettina Kjær

    2014-01-01

    Denmark has a higher incidence of cervical cancer than other Nordic countries, although all Danish women (aged 23–65) are screened regularly to identify possible cervical dysplasia or asymptomatic invasive cancer. Annually 40 000 women receives an abnormal or inadequate test result and a follow......-up recommendation. However problems with delayed follow-up may threaten the effectiveness of the Danish Cervical Cancer Screening Program, as 20% of women are delayed and dysplasia potentially can progress into cancer. Delayed follow-up is found in situations where women either consciously or unconsciously postpone...... up will be sent to the women (RCT). The intention is to ensure that all women will be notified about the test result, quickly, homogenously and in layman’s written language, still with the opportunity to contact or be contacted by the GP, if there is special needs. Furthermore, it is assumed that GP...

  4. Microbiological changes after periodontal therapy in diabetic patients with inadequate metabolic control

    Directory of Open Access Journals (Sweden)

    Carina Maciel Silva-Boghossian

    2014-05-01

    Full Text Available The present study investigated the effect of non-surgical periodontal treatment (SRP on the composition of the subgingival microbiota of chronic periodontitis (CP in individuals with type 2 diabetes (DM2 with inadequate metabolic control and in systemically healthy (SH individuals. Forty individuals (20 DM2 and 20 SH with CP underwent full-mouth periodontal examination. Subgingival plaque was sampled from 4 deep sites of each individual and tested for mean prevalence and counts of 45 bacterial taxa by the checkerboard method. Clinical and microbiological assessments were performed before and 3 months after SRP. At baseline, those in the DM2 group presented a significantly higher percentage of sites with visible plaque and bleeding on probing compared with those in the SH group (p < 0.01. Those in the DM2 group presented significantly higher levels of C. rectus and P. gingivalis, and lower prevalence of P. micra and S. anginosus, compared with those in the SH group (p ≤ 0.001. At the 3-month visit, both groups showed a significant improvement in all clinical parameters (p < 0.01. Those in the DM2 group showed significantly higher prevalence and/or levels of A. gerencseriae, A. naeslundii I, A. oris, A. odontolyticus, C. sputigena, F. periodonticum, and G. morbillorum compared with those in the SH group (p ≤ 0.001. However, those in the DM2 group showed a significant reduction in the levels of P. intermedia, P. gingivalis, T. forsythia, and T. denticola (p ≤ 0.001 over time. Those in the SRP group showed improved periodontal status and reduced levels of putative periodontal pathogens at 3 months’ evaluation compared with those in the DM2 group with inadequate metabolic control.

  5. Results of salvage radiotherapy after inadequate surgery in invasive cervical carcinoma patients: A retrospective analysis

    International Nuclear Information System (INIS)

    Saibishkumar, Elantholi P.; Patel, Firuza D.; Ghoshal, Sushmita; Kumar, Vinay; Karunanidhi, Gunaseelan; Sharma, Suresh C.

    2005-01-01

    Purpose: To evaluate the results of salvage radiotherapy (RT) after inadequate surgery in patients with invasive carcinoma of the cervix. Methods and Materials: Between 1996 and 2001, 105 invasive cervical carcinoma patients were treated at our center with external beam RT with or without intracavitary RT after having undergone total/subtotal hysterectomy at outside institutions. Results: The median follow-up was 34 months. The gap between surgery and RT was 23-198 days (median, 80). Clinically visible residual disease was present in 81 patients (77.1%). Total hysterectomy had been done in 82 patients (78%) and subtotal hysterectomy in 23 patients (22%). The 5-year overall survival, disease-free survival, and pelvic control rates of all patients were 55.2%, 53.3%, and 72.4%, respectively. On univariate analysis, older age, total hysterectomy, hemoglobin level >10 g% before RT, nonsquamous histologic type, use of intracavitary RT, a shorter gap between surgery and RT, and the absence of, or a small volume of, residual disease favorably affected the outcome. The 5-year actuarial rate of late toxicity (Radiation Therapy Oncology Group Criteria) was 19% in the rectum, 4.8% in the bladder, 24.8% in the skin, and 14.3% in the small intestine. Conclusions: Inadequate and inappropriate surgery in invasive cervical cancer with resulting gross residual disease is common in India. Factors such as the use of intracavitary RT, the correction of anemia, and a shorter gap between surgery and RT will enable postoperative RT to achieve acceptable results with minimal morbidity

  6. Patient information regarding medical radiation exposure is inadequate: Patients' experience in a university hospital

    International Nuclear Information System (INIS)

    Ukkola, L.; Oikarinen, H.; Henner, A.; Haapea, M.; Tervonen, O.

    2017-01-01

    Introduction: It is suspected that little or no information is provided to patients regarding radiological examinations. The purpose was to evaluate the coverage, content and source of this information in a university hospital. Methods: Altogether 147 patients (18–85 years) were interviewed after different examinations using a questionnaire. The patients had undergone 35 low (<1 mSv), 66 medium (1–10), and 46 high (>10) dose examinations. They were asked if they were informed about radiation use, the course or indication of the examination, the consequences of not having the examination, other options, the dose and risks of radiation, the source for the information and if any consent was enquired. Results: 52 (35%) patients did not receive any information while 95 (65%) obtained some information. Fifty-six (38%) patients received an information letter, and 75 (51%) obtained oral information, mainly from the referrer or the radiographer. The information was mostly about indication, course or radiation use, very seldom about radiation risks and the other areas. Those with a nuclear medicine examination received information more often than those with other medium- or high-dose examinations (p = 0.004). The patients scored the received information as 2.2 (mean, SD 1.3) on a Likert scale from 1 (poor) to 5 (good). Conclusion: Patients obtained inadequate information regarding radiological examinations in a university hospital. The information was provided non-systematically from various sources. The results help to set up practical guidelines for systematic information and to follow up their efficiency. The mode of operation might be helpful elsewhere in the future. - Highlights: • Patients obtained inadequate information regarding medical radiation exposure. • The information was provided non-systematically from various sources. • Patients with nuclear examinations were informed better than with other modalities. • In addition to general guidelines

  7. Composite porous scaffold of PEG/PLA support improved bone matrix deposition in vitro compared to PLA-only scaffolds.

    Science.gov (United States)

    Bhaskar, Birru; Owen, Robert; Bahmaee, Hossein; Wally, Zena; Sreenivasa Rao, Parcha; Reilly, Gwendolen C

    2018-05-01

    Controllable pore size and architecture are essential properties for tissue-engineering scaffolds to support cell ingrowth colonization. To investigate the effect of polyethylene glycol (PEG) addition on porosity and bone-cell behavior, porous polylactic acid (PLA)-PEG scaffolds were developed with varied weight ratios of PLA-PEG (100/0, 90/10, 75/25) using solvent casting and porogen leaching. Sugar 200-300 µm in size was used as a porogen. To assess scaffold suitability for bone tissue engineering, MLO-A5 murine osteoblast cells were cultured and cell metabolic activity, alkaline phosphatase (ALP) activity and bone-matrix production determined using (alizarin red S staining for calcium and direct red 80 staining for collagen). It was found that metabolic activity was significantly higher over time on scaffolds containing PEG, ALP activity and mineralized matrix production were also significantly higher on scaffolds containing 25% PEG. Porous architecture and cell distribution and penetration into the scaffold were analyzed using SEM and confocal microscopy, revealing that inclusion of PEG increased pore interconnectivity and therefore cell ingrowth in comparison to pure PLA scaffolds. The results of this study confirmed that PLA-PEG porous scaffolds support mineralizing osteoblasts better than pure PLA scaffolds, indicating they have a high potential for use in bone tissue engineering applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1334-1340, 2018. © 2018 Wiley Periodicals, Inc.

  8. Silk fibroin porous scaffolds for nucleus pulposus tissue engineering

    International Nuclear Information System (INIS)

    Zeng, Chao; Yang, Qiang; Zhu, Meifeng; Du, Lilong; Zhang, Jiamin; Ma, Xinlong; Xu, Baoshan; Wang, Lianyong

    2014-01-01

    Intervertebral discs (IVDs) are structurally complex tissue that hold the vertebrae together and provide mobility to spine. The nucleus pulposus (NP) degeneration often results in degenerative IVD disease that is one of the most common causes of back and neck pain. Tissue engineered nucleus pulposus offers an alternative approach to regain the function of the degenerative IVD. The aim of this study is to determine the feasibility of porous silk fibroin (SF) scaffolds fabricated by paraffin-sphere-leaching methods with freeze-drying in the application of nucleus pulposus regeneration. The prepared scaffold possessed high porosity of 92.38 ± 5.12% and pore size of 165.00 ± 8.25 μm as well as high pore interconnectivity and appropriate mechanical properties. Rabbit NP cells were seeded and cultured on the SF scaffolds. Scanning electron microscopy, histology, biochemical assays and mechanical tests revealed that the porous scaffolds could provide an appropriate microstructure and environment to support adhesion, proliferation and infiltration of NP cells in vitro as well as the generation of extracellular matrix. The NP cell–scaffold construction could be preliminarily formed after subcutaneously implanted in a nude mice model. In conclusion, The SF porous scaffold offers a potential candidate for tissue engineered NP tissue. - Highlights: • Paraffin microsphere-leaching method is used to fabricate silk fibroin scaffold. • The scaffold has appropriate mechanical property, porosity and pore size • The scaffold supports growth and infiltration of nucleus pulposus cells. • Nucleus pulposus cells can secrete extracellular matrix in the scaffolds. • The scaffold is a potential candidate for tissue engineered nucleus pulposus

  9. Silk fibroin porous scaffolds for nucleus pulposus tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Chao; Yang, Qiang [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Tianjin Medical University, Tianjin 300070 (China); Zhu, Meifeng [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Du, Lilong [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Tianjin Medical University, Tianjin 300070 (China); Zhang, Jiamin [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Ma, Xinlong [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Xu, Baoshan, E-mail: xubaoshan99@126.com [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Wang, Lianyong, E-mail: wly@nankai.edu.cn [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China)

    2014-04-01

    Intervertebral discs (IVDs) are structurally complex tissue that hold the vertebrae together and provide mobility to spine. The nucleus pulposus (NP) degeneration often results in degenerative IVD disease that is one of the most common causes of back and neck pain. Tissue engineered nucleus pulposus offers an alternative approach to regain the function of the degenerative IVD. The aim of this study is to determine the feasibility of porous silk fibroin (SF) scaffolds fabricated by paraffin-sphere-leaching methods with freeze-drying in the application of nucleus pulposus regeneration. The prepared scaffold possessed high porosity of 92.38 ± 5.12% and pore size of 165.00 ± 8.25 μm as well as high pore interconnectivity and appropriate mechanical properties. Rabbit NP cells were seeded and cultured on the SF scaffolds. Scanning electron microscopy, histology, biochemical assays and mechanical tests revealed that the porous scaffolds could provide an appropriate microstructure and environment to support adhesion, proliferation and infiltration of NP cells in vitro as well as the generation of extracellular matrix. The NP cell–scaffold construction could be preliminarily formed after subcutaneously implanted in a nude mice model. In conclusion, The SF porous scaffold offers a potential candidate for tissue engineered NP tissue. - Highlights: • Paraffin microsphere-leaching method is used to fabricate silk fibroin scaffold. • The scaffold has appropriate mechanical property, porosity and pore size • The scaffold supports growth and infiltration of nucleus pulposus cells. • Nucleus pulposus cells can secrete extracellular matrix in the scaffolds. • The scaffold is a potential candidate for tissue engineered nucleus pulposus.

  10. Scaffold hopping in drug discovery using inductive logic programming.

    Science.gov (United States)

    Tsunoyama, Kazuhisa; Amini, Ata; Sternberg, Michael J E; Muggleton, Stephen H

    2008-05-01

    In chemoinformatics, searching for compounds which are structurally diverse and share a biological activity is called scaffold hopping. Scaffold hopping is important since it can be used to obtain alternative structures when the compound under development has unexpected side-effects. Pharmaceutical companies use scaffold hopping when they wish to circumvent prior patents for targets of interest. We propose a new method for scaffold hopping using inductive logic programming (ILP). ILP uses the observed spatial relationships between pharmacophore types in pretested active and inactive compounds and learns human-readable rules describing the diverse structures of active compounds. The ILP-based scaffold hopping method is compared to two previous algorithms (chemically advanced template search, CATS, and CATS3D) on 10 data sets with diverse scaffolds. The comparison shows that the ILP-based method is significantly better than random selection while the other two algorithms are not. In addition, the ILP-based method retrieves new active scaffolds which were not found by CATS and CATS3D. The results show that the ILP-based method is at least as good as the other methods in this study. ILP produces human-readable rules, which makes it possible to identify the three-dimensional features that lead to scaffold hopping. A minor variant of a rule learnt by ILP for scaffold hopping was subsequently found to cover an inhibitor identified by an independent study. This provides a successful result in a blind trial of the effectiveness of ILP to generate rules for scaffold hopping. We conclude that ILP provides a valuable new approach for scaffold hopping.

  11. Strategic Cognition of Social Media in Business-Customer Interaction

    OpenAIRE

    Rydén, Pernille

    2015-01-01

    This dissertation contributes to the strategic cognition research by exploring how managers’ cognitive representations of an emerging, but potentially disruptive technology, influence their identification of strategic options. Managers tend to talk of social media as technology that changes customer behavior and disrupts industries, however, this attitude is not reflected in their strategic framing and implementation of social media. As behavioral theory seems inadequate to acc...

  12. Visual cognition

    Energy Technology Data Exchange (ETDEWEB)

    Pinker, S.

    1985-01-01

    This book consists of essays covering issues in visual cognition presenting experimental techniques from cognitive psychology, methods of modeling cognitive processes on computers from artificial intelligence, and methods of studying brain organization from neuropsychology. Topics considered include: parts of recognition; visual routines; upward direction; mental rotation, and discrimination of left and right turns in maps; individual differences in mental imagery, computational analysis and the neurological basis of mental imagery: componental analysis.

  13. Improving access to shared decision-making for Hispanics/Latinos with inadequately controlled type 2 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Davidson JA

    2015-04-01

    Full Text Available Jaime A Davidson,1 Aracely Rosales,2 Alicia C Shillington,3 Robert A Bailey,4 Chris Kabir,3 Guillermo E Umpierrez51Touchstone Diabetes Center, University of Texas Southwestern Medical Center, Dallas, TX, USA; 2Rosales Communications, Philadelphia, PA, USA; 3EPI-Q, Inc., Oakbrook, IL, USA; 4Health Economics and Outcomes Research, Janssen Scientific Affairs, LLC, Raritan, NJ, USA; 5Division of Endocrinology and Metabolism, Emory University, Atlanta, Georgia, GA, USAPurpose: To describe the cultural and linguistic adaptation and Spanish translation of an English-language patient decision aid (PDA for use in supporting shared decision-making in Hispanics/Latinos with type 2 diabetes mellitus (T2DM, a group at a high risk for complications.Patients and methods: A steering committee of endocrinologists, a primary care physician, a certified diabetes educator, and a dietician, each with extensive experience in providing care to Hispanics/Latinos was convened to assess a PDA developed for English-speaking patients with T2DM. English content was reviewed for cultural sensitivity and appropriateness for a Hispanic/Latino population. A consensus-building process and iterative version edits incorporated clinician perspectives. The content was adapted to be consistent with traditional Hispanic/Latino cultural communication precepts (eg, avoidance of hostile confrontation; value for warm interaction; respect for authority; value of family support for decisions. The PDA was translated by native-speaking individuals with diabetes expertise.Results: The PDA underwent testing during cognitive interviews with ten Spanish-speaking Hispanics/Latinos with T2DM to ensure that the content is reflective of the experience, understanding, and language Hispanic/Latino patients use to describe diabetes and treatment. Content edits were made to assure a literacy level appropriate to the audience, and the PDA was produced for online video dissemination.Conclusion: High

  14. Cytocompatibility of a silk fibroin tubular scaffold

    International Nuclear Information System (INIS)

    Wang, Jiannan; Wei, Yali; Yi, Honggen; Liu, Zhiwu; Sun, Dan; Zhao, Huanrong

    2014-01-01

    Regenerated silk fibroin (SF) materials are increasingly used for tissue engineering applications. In order to explore the feasibility of a novel biomimetic silk fibroin tubular scaffold (SFTS) crosslinked by poly(ethylene glycol) diglycidyl ether (PEG-DE), biocompatibility with cells was evaluated. The novel biomimetic design of the SFTS consisted of three distinct layers: a regenerated SF intima, a silk braided media and a regenerated SF adventitia. The SFTS exhibited even silk fibroin penetration throughout the braid, forming a porous layered tube with superior mechanical, permeable and cell adhesion properties that are beneficial to vascular regeneration. Cytotoxicity and cell compatibility were tested on L929 cells and human umbilical vein endothelial cells (EA.hy926). DNA content analysis, scanning electron and confocal microscopies and MTT assay showed no inhibitory effects on DNA replication. Cell morphology, viability and proliferation were good for L929 cells, and satisfactory for EA.hy926 cells. Furthermore, the suture retention strength of the SFTS was about 23 N and the Young's modulus was 0.2–0.3 MPa. Collectively, these data demonstrate that PEG-DE crosslinked SFTS possesses the appropriate cytocompatibility and mechanical properties for use as vascular scaffolds as an alternative to vascular autografts. - Highlights: • A PEG-DE cross-linked small caliber porous silk fibroin tubular scaffold (SFTS) • PEG-DE cross-linked SF film had no inhibitory effect on DNA replication of cells. • Cells cultured on the SFTS showed good morphology, cell viability and proliferative activity. • SFTS would be beneficial to endothelialization. • SFTS had good suture retention strength and flexibility

  15. Porous allograft bone scaffolds: doping with strontium.

    Directory of Open Access Journals (Sweden)

    Yantao Zhao

    Full Text Available Strontium (Sr can promote the process of bone formation. To improve bioactivity, porous allograft bone scaffolds (ABS were doped with Sr and the mechanical strength and bioactivity of the scaffolds were evaluated. Sr-doped ABS were prepared using the ion exchange method. The density and distribution of Sr in bone scaffolds were investigated by inductively coupled plasma optical emission spectrometry (ICP-OES, X-ray photoelectron spectroscopy (XPS, and energy-dispersive X-ray spectroscopy (EDS. Controlled release of strontium ions was measured and mechanical strength was evaluated by a compressive strength test. The bioactivity of Sr-doped ABS was investigated by a simulated body fluid (SBF assay, cytotoxicity testing, and an in vivo implantation experiment. The Sr molar concentration [Sr/(Sr+Ca] in ABS surpassed 5% and Sr was distributed nearly evenly. XPS analyses suggest that Sr combined with oxygen and carbonate radicals. Released Sr ions were detected in the immersion solution at higher concentration than calcium ions until day 30. The compressive strength of the Sr-doped ABS did not change significantly. The bioactivity of Sr-doped material, as measured by the in vitro SBF immersion method, was superior to that of the Sr-free freeze-dried bone and the Sr-doped material did not show cytotoxicity compared with Sr-free culture medium. The rate of bone mineral deposition for Sr-doped ABS was faster than that of the control at 4 weeks (3.28 ± 0.23 µm/day vs. 2.60 ± 0.20 µm/day; p<0.05. Sr can be evenly doped into porous ABS at relevant concentrations to create highly active bone substitutes.

  16. Cognitive Readiness

    National Research Council Canada - National Science Library

    Morrison, John

    2002-01-01

    Cognitive readiness is described as the mental preparation an individual needs to establish and sustain competent performance in the complex and unpredictable environment of modern military operations...

  17. Scaffold engineering: a bridge to where?

    International Nuclear Information System (INIS)

    Hollister, Scott J

    2009-01-01

    A significant amount of federal research funding (over $4 billion) has gone into tissue engineering over the last 20 years. This has led to an exponential increase in research productivity as evidenced by the number of published papers referencing 'tissue engineering' and 'scaffold'. However, the number of tissue engineering products resulting from this research remains a paltry few, of which true tissue engineering products can be counted using the fingers of two hands. The fundamental question remains 'Why does such a gap exist between research and translation?'. This paper argues that such a gap exists in part due to the research paradigms followed in tissue engineering, in which a linear model is followed that assumed individual technical discovery can be bundled into model tissue engineering systems, followed by manufacturing scale up and regulatory approval. As such, most research funding follows this linear model with the vast majority of research spent on the discovery phase. This includes funding on both cell therapy and scaffold materials and engineering. It is assumed that therapy systems can readily be constructed by combining disparate technologies derived in different laboratories and that these therapies can readily achieve regulatory approval. Yet, most tissue engineering technologies fail to make it to clinical application because they simply have not been engineered for these specific applications or cannot be scaled to clinical level production. This paper argues that a different research paradigm is needed, essentially that of Pasteur's Quadrant proposed by Donald Stokes in the book of the same name. In this paradigm, research is pursued from the twin perspective of end use and the need for fundamental understanding. From this perspective, more funding emphasis should be placed on scalable manufacturing of systems that are designed for specific clinical applications that can attain regulatory approval. Funding of such scaffold/cell manufacturing

  18. Scaffolded filmmaking in PlayOFF

    DEFF Research Database (Denmark)

    Philipsen, Heidi

    2012-01-01

    How is it possible to make an entire short film in only 48 hours? This task was carried out in the global online film contest, called PlayOFF, held by Odense International Film Festival (OFF) in August 2010 and -11. Contestants from all over the world - as different countries as Palestine, China...... the productions. This article is based on an empirical study of film processes in PlayOFF 2010 and -11, and I will point out how these findings could be used in developing creativity. Based on my empirical studies I will suggest a learning design for scaffolded filmmaking and propose some ideas of how to transfer...

  19. Printing and Prototyping of Tissues and Scaffolds

    Science.gov (United States)

    Derby, Brian

    2012-11-01

    New manufacturing technologies under the banner of rapid prototyping enable the fabrication of structures close in architecture to biological tissue. In their simplest form, these technologies allow the manufacture of scaffolds upon which cells can grow for later implantation into the body. A more exciting prospect is the printing and patterning in three dimensions of all the components that make up a tissue (cells and matrix materials) to generate structures analogous to tissues; this has been termed bioprinting. Such techniques have opened new areas of research in tissue engineering and regenerative medicine.

  20. Porous ceramic scaffolds with complex architectures

    Science.gov (United States)

    Munch, E.; Franco, J.; Deville, S.; Hunger, P.; Saiz, E.; Tomsia, A. P.

    2008-06-01

    This work compares two novel techniques for the fabrication of ceramic scaffolds for bone tissue engineering with complex porosity: robocasting and freeze casting. Both techniques are based on the preparation of concentrated ceramic suspensions with suitable properties for the process. In robocasting, the computer-guided deposition of the suspensions is used to build porous materials with designed three dimensional geometries and microstructures. Freeze casting uses ice crystals as a template to form porous lamellar ceramic materials. Preliminary results on the compressive strengths of the materials are also reported.

  1. Cognitive anthropology is a cognitive science.

    Science.gov (United States)

    Boster, James S

    2012-07-01

    Cognitive anthropology contributes to cognitive science as a complement to cognitive psychology. The chief threat to its survival has not been rejection by other cognitive scientists but by other cultural anthropologists. It will remain a part of cognitive science as long as cognitive anthropologists research, teach, and publish. Copyright © 2012 Cognitive Science Society, Inc.

  2. Ethnic differences in disability risk between Dutch and Turkish scaffolders

    NARCIS (Netherlands)

    Elders, L.A.M.; Burdorf, A.; Öry, F.G.

    2004-01-01

    The number of native Dutch and Turkish workers receiving a permanent disability pension in the Netherlands is still rising. To assess ethnic differences in disability risk between Dutch and Turkish scaffolders, a retrospective study was conducted within a large scaffolding company. Medical files for

  3. The effect of scaffold pore size in cartilage tissue engineering.

    Science.gov (United States)

    Nava, Michele M; Draghi, Lorenza; Giordano, Carmen; Pietrabissa, Riccardo

    2016-07-26

    The effect of scaffold pore size and interconnectivity is undoubtedly a crucial factor for most tissue engineering applications. The aim of this study was to examine the effect of pore size and porosity on cartilage construct development in different scaffolds seeded with articular chondrocytes. We fabricated poly-L-lactide-co-trimethylene carbonate scaffolds with different pore sizes, using a solvent-casting/particulate-leaching technique. We seeded primary bovine articular chondrocytes on these scaffolds, cultured the constructs for 2 weeks and examined cell proliferation, viability and cell-specific production of cartilaginous extracellular matrix proteins, including GAG and collagen. Cell density significantly increased up to 50% with scaffold pore size and porosity, likely facilitated by cell spreading on the internal surface of bigger pores, and by increased mass transport of gases and nutrients to cells, and catabolite removal from cells, allowed by lower diffusion barriers in scaffolds with a higher porosity. However, both the cell metabolic activity and the synthesis of cartilaginous matrix proteins significantly decreased by up to 40% with pore size. We propose that the association of smaller pore diameters, causing 3-dimensional cell aggregation, to a lower oxygenation caused by a lower porosity, could have been the condition that increased the cell-specific synthesis of cartilaginous matrix proteins in the scaffold with the smallest pores and the lowest porosity among those tested. In the initial steps of in vitro cartilage engineering, the combination of small scaffold pores and low porosity is an effective strategy with regard to the promotion of chondrogenesis.

  4. Using the Community of Inquiry Framework to Scaffold Online Tutoring

    Science.gov (United States)

    Feng, Xiaoying; Xie, Jingjing; Liu, Yue

    2017-01-01

    Tutoring involves providing learners with a suitable level of structure and guidance to support their learning. This study reports on an exploration of how to design such structure and guidance (i.e., learning scaffolds) in the Chinese online educational context, and in so doing, answer the following two questions: (a) What scaffolding strategies…

  5. Enzymatically biomineralized chitosan scaffolds for tissue-engineering applications.

    NARCIS (Netherlands)

    Dash, M.; Samal, S.K.; Douglas, T.E.L.; Schaubroeck, D.; Leeuwenburgh, S.C.G.; Voort, P. van der; Declercq, H.A.; Dubruel, P.

    2017-01-01

    Porous biodegradable scaffolds represent promising candidates for tissue-engineering applications because of their capability to be preseeded with cells. We report an uncrosslinked chitosan scaffold designed with the aim of inducing and supporting enzyme-mediated formation of apatite minerals in the

  6. Scaffolding of Small Groups' Metacognitive Activities with an Avatar

    Science.gov (United States)

    Molenaar, Inge; Chiu, Ming Ming; Sleegers, Peter; van Boxtel, Carla

    2011-01-01

    Metacognitive scaffolding in a computer-supported learning environment can influence students' metacognitive activities, metacognitive knowledge and domain knowledge. In this study we analyze how metacognitive activities mediate the relationships between different avatar scaffolds on students' learning. Multivariate, multilevel analysis of the…

  7. Metacognitive Scaffolding during Collaborative Learning: A Promising Combination

    Science.gov (United States)

    Molenaar, Inge; Sleegers, Peter; van Boxtel, Carla

    2014-01-01

    This article explores the effect of computerized scaffolding with different scaffolds (structuring vs. problematizing) on intra-group metacognitive interaction. In this study, we investigate 4 types of intra-group social metacognitive activities; namely ignored, accepted, shared and co-constructed metacognitive activities in 18 triads (6 control…

  8. Maternal Scaffolding and Attention Regulation in Children Living in Poverty

    Science.gov (United States)

    Robinson, Julia B.; Burns, Barbara M.; Davis, Deborah Winders

    2009-01-01

    This study examines the relation of maternal scaffolding and children's attention regulation abilities in preschool children from low-income families within the context of a parent-child interaction task and in a child-alone task. Maternal scaffolding behaviors differed for mothers of children with different attention regulation skills. Mothers…

  9. Anisotropic silk fibroin/gelatin scaffolds from unidirectional freezing

    Energy Technology Data Exchange (ETDEWEB)

    Asuncion, Maria Christine Tankeh, E-mail: christine.asuncion@u.nus.edu [National University of Singapore, Department of Biomedical Engineering (Singapore); Goh, James Cho-Hong [National University of Singapore, Department of Biomedical Engineering (Singapore); National University of Singapore, Department of Orthopedic Surgery (Singapore); Toh, Siew-Lok [National University of Singapore, Department of Biomedical Engineering (Singapore); National University of Singapore, Department of Mechanical Engineering (Singapore)

    2016-10-01

    Recent studies have underlined the importance of matching scaffold properties to the biological milieu. Tissue, and thus scaffold, anisotropy is one such property that is important yet sometimes overlooked. Methods that have been used to achieve anisotropic scaffolds present challenges such as complicated fabrication steps, harsh processing conditions and toxic chemicals involved. In this study, unidirectional freezing was employed to fabricate anisotropic silk fibroin/gelatin scaffolds in a simple and mild manner. Morphological, mechanical, chemical and cellular compatibility properties were investigated, as well as the effect of the addition of gelatin to certain properties of the scaffold. It was shown that scaffold properties were suitable for cell proliferation and that mesenchymal stem cells were able to align themselves along the directed fibers. The fabricated scaffolds present a platform that can be used for anisotropic tissue engineering applications such as cardiac patches. - Highlights: • Silk/gelatin scaffolds with unidirectional alignment were fabricated using a simple and scalable process • Presence of gelatin in silk resulted to lesser shrinkage, better water retention and improved cell proliferation. • Mesenchymal stem cells were shown to align themselves according to the fiber alignment.

  10. Bioactive Scaffolds for Regeneration of Cartilage and Subchondral Bone Interface

    Science.gov (United States)

    Deng, Cuijun; Zhu, Huiying; Li, Jiayi; Feng, Chun; Yao, Qingqiang; Wang, Liming; Chang, Jiang; Wu, Chengtie

    2018-01-01

    The cartilage lesion resulting from osteoarthritis (OA) always extends into subchondral bone. It is of great importance for simultaneous regeneration of two tissues of cartilage and subchondral bone. 3D-printed Sr5(PO4)2SiO4 (SPS) bioactive ceramic scaffolds may achieve the aim of regenerating both of cartilage and subchondral bone. We hypothesized that strontium (Sr) and silicon (Si) ions released from SPS scaffolds play a crucial role in osteochondral defect reconstruction. Methods: SPS bioactive ceramic scaffolds were fabricated by a 3D-printing method. The SEM and ICPAES were used to investigate the physicochemical properties of SPS scaffolds. The proliferation and maturation of rabbit chondrocytes stimulated by SPS bioactive ceramics were measured in vitro. The stimulatory effect of SPS scaffolds for cartilage and subchondral bone regeneration was investigated in vivo. Results: SPS scaffolds significantly stimulated chondrocyte proliferation, and SPS extracts distinctly enhanced the maturation of chondrocytes and preserved chondrocytes from OA. SPS scaffolds markedly promoted the regeneration of osteochondral defects. The complex interface microstructure between cartilage and subchondral bone was obviously reconstructed. The underlying mechanism may be related to Sr and Si ions stimulating cartilage regeneration by activating HIF pathway and promoting subchondral bone reconstruction through activating Wnt pathway, as well as preserving chondrocytes from OA via inducing autophagy and inhibiting hedgehog pathway. Conclusion: Our findings suggest that SPS scaffolds can help osteochondral defect reconstruction and well reconstruct the complex interface between cartilage and subchondral bone, which represents a promising strategy for osteochondral defect regeneration. PMID:29556366

  11. Multiscale fabrication of biomimetic scaffolds for tympanic membrane tissue engineering

    International Nuclear Information System (INIS)

    Mota, Carlos; Danti, Serena; D’Alessandro, Delfo; Trombi, Luisa; Ricci, Claudio; Berrettini, Stefano; Puppi, Dario; Dinucci, Dinuccio; Chiellini, Federica; Milazzo, Mario; Stefanini, Cesare; Moroni, Lorenzo

    2015-01-01

    The tympanic membrane (TM) is a thin tissue able to efficiently collect and transmit sound vibrations across the middle ear thanks to the particular orientation of its collagen fibers, radiate on one side and circular on the opposite side. Through the combination of advanced scaffolds and autologous cells, tissue engineering (TE) could offer valuable alternatives to autografting in major TM lesions. In this study, a multiscale approach based on electrospinning (ES) and additive manufacturing (AM) was investigated to fabricate scaffolds, based on FDA approved copolymers, resembling the anatomic features and collagen fiber arrangement of the human TM. A single scale TM scaffold was manufactured using a custom-made collector designed to confer a radial macro-arrangement to poly(lactic-co-glycolic acid) electrospun fibers during their deposition. Dual and triple scale scaffolds were fabricated combining conventional ES with AM to produce poly(ethylene oxide terephthalate)/poly(butylene terephthalate) block copolymer scaffolds with anatomic-like architecture. The processing parameters were optimized for each manufacturing method and copolymer. TM scaffolds were cultured in vitro with human mesenchymal stromal cells, which were viable, metabolically active and organized following the anisotropic character of the scaffolds. The highest viability, cell density and protein content were detected in dual and triple scale scaffolds. Our findings showed that these biomimetic micro-patterned substrates enabled cell disposal along architectural directions, thus appearing as promising substrates for developing functional TM replacements via TE. (paper)

  12. Scaffolding and Dialogic Teaching in Mathematics Education: Introduction and Review

    Science.gov (United States)

    Bakker, Arthur; Smit, Jantien; Wegerif, Rupert

    2015-01-01

    This article has two purposes: firstly to introduce this special issue on scaffolding and dialogic teaching in mathematics education and secondly to review the recent literature on these topics as well as the articles in this special issue. First we define and characterise scaffolding and dialogic teaching and provide a brief historical overview…

  13. Scaffolding Performance in EPSSs: Bridging Theory and Practice.

    Science.gov (United States)

    Hannafin, Michael J; McCarthy, James E.; Hannafin, Kathleen M.; Radtke, Paul

    Electronic performance support systems (EPSS) help users accomplish tasks, using computational technologies. Scaffolding is the process through which efforts are supported while engaging a learning or performance task. A number of different types of scaffolds are possible, including conceptual, metacognitive, procedural, and strategic. Each of…

  14. Biomimetic mineral-organic composite scaffolds with controlled internal architecture.

    Science.gov (United States)

    Manjubala, I; Woesz, Alexander; Pilz, Christine; Rumpler, Monika; Fratzl-Zelman, Nadja; Roschger, Paul; Stampfl, Juergen; Fratzl, Peter

    2005-12-01

    Bone and cartilage generation by three-dimensional scaffolds is one of the promising techniques in tissue engineering. One approach is to generate histologically and functionally normal tissue by delivering healthy cells in biocompatible scaffolds. These scaffolds provide the necessary support for cells to proliferate and maintain their differentiated function, and their architecture defines the ultimate shape. Rapid prototyping (RP) is a technology by which a complex 3-dimensional (3D) structure can be produced indirectly from computer aided design (CAD). The present study aims at developing a 3D organic-inorganic composite scaffold with defined internal architecture by a RP method utilizing a 3D printer to produce wax molds. The composite scaffolds consisting of chitosan and hydroxyapatite were prepared using soluble wax molds. The behaviour and response of MC3T3-E1 pre-osteoblast cells on the scaffolds was studied. During a culture period of two and three weeks, cell proliferation and in-growth were observed by phase contrast light microscopy, histological staining and electron microscopy. The Giemsa and Gömöri staining of the cells cultured on scaffolds showed that the cells proliferated not only on the surface, but also filled the micro pores of the scaffolds and produced extracellular matrix within the pores. The electron micrographs showed that the cells covering the surface of the struts were flattened and grew from the periphery into the middle region of the pores.

  15. Apple derived cellulose scaffolds for 3D mammalian cell culture.

    Directory of Open Access Journals (Sweden)

    Daniel J Modulevsky

    Full Text Available There are numerous approaches for producing natural and synthetic 3D scaffolds that support the proliferation of mammalian cells. 3D scaffolds better represent the natural cellular microenvironment and have many potential applications in vitro and in vivo. Here, we demonstrate that 3D cellulose scaffolds produced by decellularizing apple hypanthium tissue can be employed for in vitro 3D culture of NIH3T3 fibroblasts, mouse C2C12 muscle myoblasts and human HeLa epithelial cells. We show that these cells can adhere, invade and proliferate in the cellulose scaffolds. In addition, biochemical functionalization or chemical cross-linking can be employed to control the surface biochemistry and/or mechanical properties of the scaffold. The cells retain high viability even after 12 continuous weeks of culture and can achieve cell densities comparable with other natural and synthetic scaffold materials. Apple derived cellulose scaffolds are easily produced, inexpensive and originate from a renewable source. Taken together, these results demonstrate that naturally derived cellulose scaffolds offer a complementary approach to existing techniques for the in vitro culture of mammalian cells in a 3D environment.

  16. 29 CFR 1915.71 - Scaffolds or staging.

    Science.gov (United States)

    2010-07-01

    ... construction of scaffolds shall be spruce, fir, long leaf yellow pine, Oregon pine or wood of equal strength... large, loose or dead knots. It shall also be free from dry rot, large checks, worm holes or other... accidentally disengaged from the crane hook. (c) Independent pole wood scaffolds. (1) All pole uprights shall...

  17. Design of a bioresorbable polymeric scaffold for osteoblast culture

    Science.gov (United States)

    Ditaranto, Vincent M., Jr.

    Bioresorbable polymeric scaffolds were designed for the purpose of growing rat osteosarcoma cells (ROS 17/2.8) using the compression molding method. The material used in the construction of the scaffolds was a mixture of polycaprolactone (PCL), Hydroxyapatite (HA), Glycerin (GL) and salt (NaCl) for porosity. The concentration of the several materials utilized, was determined by volume. Past research at the University of Massachusetts Lowell (UML) has successfully utilized the compression molding method for the construction of scaffolds, but was unable to accomplish the goal of long term cell survival and complete cellular proliferation throughout a three dimensional scaffold. This research investigated various concentrations of the materials and molding temperatures used for the manufacture of scaffolds in order to improve the scaffold design and address those issues. The design of the scaffold using the compression molding process is detailed in the Method and Materials section of this thesis. The porogen (salt) used for porosity was suspected as a possible source of contamination causing cell apoptosis in past studies. This research addressed the issues for cell survival and proliferation throughout a three dimensional scaffold. The leaching of the salt was one major design modification. This research successfully used ultrasonic leaching in addition to the passive method. Prior to cell culture, the scaffolds were irradiated to 2.75 Mrad, with cobalt-60 gamma radionuclide. The tissue culture consisted of two trials: (1) cell culture in scaffolds cleaned with passive leaching; (2) cell culture with scaffolds cleaned with ultrasonic leaching. Cell survival and proliferation was accomplished only with the addition of ultrasonic leaching of the scaffolds. Analysis of the scaffolds included Scanning Electron Microscopy (SEM), Nikon light microscopy and x-ray mapping of the calcium, sodium and chloride ion distribution. The cells were analyzed by Environmental Scanning

  18. Bionic Design, Materials and Performance of Bone Tissue Scaffolds

    Directory of Open Access Journals (Sweden)

    Tong Wu

    2017-10-01

    Full Text Available Design, materials, and performance are important factors in the research of bone tissue scaffolds. This work briefly describes the bone scaffolds and their anatomic structure, as well as their biological and mechanical characteristics. Furthermore, we reviewed the characteristics of metal materials, inorganic materials, organic polymer materials, and composite materials. The importance of the bionic design in preoperative diagnosis models and customized bone scaffolds was also discussed, addressing both the bionic structure design (macro and micro structure and the bionic performance design (mechanical performance and biological performance. Materials and performance are the two main problems in the development of customized bone scaffolds. Bionic design is an effective way to solve these problems, which could improve the clinical application of bone scaffolds, by creating a balance between mechanical performance and biological performance.

  19. Mesenchymal stem cell ingrowth and differentiation on coralline hydroxyapatite scaffolds

    DEFF Research Database (Denmark)

    Mygind, Tina; Stiehler, Maik; Baatrup, Anette

    2007-01-01

    Culture of osteogenic cells on a porous scaffold could offer a new solution to bone grafting using autologous human mesenchymal stem cells (hMSC) from the patient. We compared coralline hydroxyapatite scaffolds with pore sizes of 200 and 500 microm for expansion and differentiation of hMSCs. We...... polymerase chain reaction for 10 osteogenic markers. The 500-microm scaffolds had increased proliferation rates and accommodated a higher number of cells (shown by DNA content, scanning electron microscopy and fluorescence microscopy). Thus the porosity of a 3D microporous biomaterial may be used to steer h......MSC in a particular direction. We found that dynamic spinner flask cultivation of hMSC/scaffold constructs resulted in increased proliferation, differentiation and distribution of cells in scaffolds. Therefore, spinner flask cultivation is an easy-to-use inexpensive system for cultivating hMSCs on small...

  20. Electrospun PVA-PCL-HAB scaffold for craniofacial bone regeneration

    DEFF Research Database (Denmark)

    Prabha, Rahul; Kraft, David Christian Evar; Melsen, Birte

    2015-01-01

    -caprolactone (PCL)- triphasic bioceramic(HAB) scaffold to biomimic native tissue and we tested its ability to support osteogenic differentiation of stromal stem cells ( MSC) and its suitability for regeneration of craniofa- cial defects. Physiochemical characterizations of the scaffold, including con- tact angle...... body fluid immersed scaffold samples. Culturing human adult dental pulp stem cells (DPSC) and human bone marrow derived MSC seeded on PVA-PCL-HAB scaffold showed enhanced cell proliferation and in vitro osteoblastic differentiation. Cell-containing scaffolds were implanted subcutaneously in immune...... deficient mice. Histologic ex- amination of retrieved implant sections stained with H&E, Col- lagenType I and Human Vimentin antibody demonstrated that the cells survived in vivo in the implants for at least 8 weeks with evidence of osteoblastic differentiation and angiogenesis within the implants. Our...

  1. Risk of Performance Decrement and Crew Illness Due to an Inadequate Food System

    Science.gov (United States)

    Douglas, Grace L.; Cooper, Maya; Bermudez-Aguirre, Daniela; Sirmons, Takiyah

    2016-01-01

    NASA is preparing for long duration manned missions beyond low-Earth orbit that will be challenged in several ways, including long-term exposure to the space environment, impacts to crew physiological and psychological health, limited resources, and no resupply. The food system is one of the most significant daily factors that can be altered to improve human health, and performance during space exploration. Therefore, the paramount importance of determining the methods, technologies, and requirements to provide a safe, nutritious, and acceptable food system that promotes crew health and performance cannot be underestimated. The processed and prepackaged food system is the main source of nutrition to the crew, therefore significant losses in nutrition, either through degradation of nutrients during processing and storage or inadequate food intake due to low acceptability, variety, or usability, may significantly compromise the crew's health and performance. Shelf life studies indicate that key nutrients and quality factors in many space foods degrade to concerning levels within three years, suggesting that food system will not meet the nutrition and acceptability requirements of a long duration mission beyond low-Earth orbit. Likewise, mass and volume evaluations indicate that the current food system is a significant resource burden. Alternative provisioning strategies, such as inclusion of bioregenerative foods, are challenged with resource requirements, and food safety and scarcity concerns. Ensuring provisioning of an adequate food system relies not only upon determining technologies, and requirements for nutrition, quality, and safety, but upon establishing a food system that will support nutritional adequacy, even with individual crew preference and self-selection. In short, the space food system is challenged to maintain safety, nutrition, and acceptability for all phases of an exploration mission within resource constraints. This document presents the

  2. Tofacitinib for Psoriatic Arthritis in Patients with an Inadequate Response to TNF Inhibitors.

    Science.gov (United States)

    Gladman, Dafna; Rigby, William; Azevedo, Valderilio F; Behrens, Frank; Blanco, Ricardo; Kaszuba, Andrzej; Kudlacz, Elizabeth; Wang, Cunshan; Menon, Sujatha; Hendrikx, Thijs; Kanik, Keith S

    2017-10-19

    Tofacitinib is an oral Janus kinase inhibitor that is under investigation for the treatment of psoriatic arthritis. We evaluated tofacitinib in patients with active psoriatic arthritis who had previously had an inadequate response to tumor necrosis factor (TNF) inhibitors. In this 6-month randomized, placebo-controlled, double-blind, phase 3 trial, we randomly assigned 395 patients, in a 2:2:1:1 ratio, to four regimens: 5 mg of tofacitinib administered orally twice daily (132 patients); 10 mg of tofacitinib twice daily (132 patients); placebo, with a switch to 5 mg of tofacitinib twice daily at 3 months (66 patients); or placebo, with a switch to 10 mg of tofacitinib twice daily at 3 months (65 patients). Data from the patients who received placebo during the first 3 months of the trial were pooled. The primary end points were the percentage of patients who had at least 20% improvement according to the criteria of the American College of Rheumatology (ACR20 response) and the change from baseline score on the Health Assessment Questionnaire-Disability Index (HAQ-DI; scores range from 0 to 3, with higher scores indicating greater disability) at the month 3 analysis. At 3 months, the rates of ACR20 response were 50% with the 5-mg dose of tofacitinib and 47% with the 10-mg dose, as compared with 24% with placebo (Ptofacitinib continuously and in 6% who received the 10-mg dose continuously. Over the course of 6 months, there were four serious infections, three herpes zoster infections, one myocardial infarction, and one ischemic stroke among the patients who received tofacitinib continuously. Elevations of aspartate and alanine aminotransferase concentrations of three or more times the upper limit of the normal range occurred in more patients who received tofacitinib continuously than in patients who received placebo followed by tofacitinib. In this trial involving patients with active psoriatic arthritis who had had an inadequate response to TNF inhibitors, tofacitinib

  3. Magnetic responsive hydroxyapatite composite scaffolds construction for bone defect reparation

    Directory of Open Access Journals (Sweden)

    Zeng XB

    2012-07-01

    Full Text Available Xiao Bo Zeng, Hao Hu, Li Qin Xie, Fang Lan, Wen Jiang, Yao Wu, Zhong Wei GuNational Engineering Research Center for Biomaterials, Sichuan University, Chengdu, Sichuan, People's Republic of ChinaIntroduction: In recent years, interest in magnetic biomimetic scaffolds for tissue engineering has increased considerably. A type of magnetic scaffold composed of magnetic nanoparticles (MNPs and hydroxyapatite (HA for bone repair has been developed by our research group.Aim and methods: In this study, to investigate the influence of the MNP content (in the scaffolds on the cell behaviors and the interactions between the magnetic scaffold and the exterior magnetic field, a series of MNP-HA magnetic scaffolds with different MNP contents (from 0.2% to 2% were fabricated by immersing HA scaffold into MNP colloid. ROS 17/2.8 and MC3T3-E1 cells were cultured on the scaffolds in vitro, with and without an exterior magnetic field, respectively. The cell adhesion, proliferation and differentiation were evaluated via scanning electron microscopy; confocal laser scanning microscopy; and 3-(4,5-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT, alkaline phosphatase, and bone gla protein activity tests.Results: The results demonstrated the positive influence of the magnetic scaffolds on cell adhesion, proliferation, and differentiation. Further, a higher amount of MNPs on the magnetic scaffolds led to more significant stimulation.Conclusion: The magnetic scaffold can respond to the exterior magnetic field and engender some synergistic effect to intensify the stimulating effect of a magnetic field to the proliferation and differentiation of cells.Keywords: magnetic therapy, magnetic nanoparticles, bone repair, magnetic responsive

  4. Scaffold library for tissue engineering: a geometric evaluation.

    Science.gov (United States)

    Chantarapanich, Nattapon; Puttawibul, Puttisak; Sucharitpwatskul, Sedthawatt; Jeamwatthanachai, Pongnarin; Inglam, Samroeng; Sitthiseripratip, Kriskrai

    2012-01-01

    Tissue engineering scaffold is a biological substitute that aims to restore, to maintain, or to improve tissue functions. Currently available manufacturing technology, that is, additive manufacturing is essentially applied to fabricate the scaffold according to the predefined computer aided design (CAD) model. To develop scaffold CAD libraries, the polyhedrons could be used in the scaffold libraries development. In this present study, one hundred and nineteen polyhedron models were evaluated according to the established criteria. The proposed criteria included considerations on geometry, manufacturing feasibility, and mechanical strength of these polyhedrons. CAD and finite element (FE) method were employed as tools in evaluation. The result of evaluation revealed that the close-cellular scaffold included truncated octahedron, rhombicuboctahedron, and rhombitruncated cuboctahedron. In addition, the suitable polyhedrons for using as open-cellular scaffold libraries included hexahedron, truncated octahedron, truncated hexahedron, cuboctahedron, rhombicuboctahedron, and rhombitruncated cuboctahedron. However, not all pore size to beam thickness ratios (PO:BT) were good for making the open-cellular scaffold. The PO:BT ratio of each library, generating the enclosed pore inside the scaffold, was excluded to avoid the impossibility of material removal after the fabrication. The close-cellular libraries presented the constant porosity which is irrespective to the different pore sizes. The relationship between PO:BT ratio and porosity of open-cellular scaffold libraries was displayed in the form of Logistic Power function. The possibility of merging two different types of libraries to produce the composite structure was geometrically evaluated in terms of the intersection index and was mechanically evaluated by means of FE analysis to observe the stress level. The couples of polyhedrons presenting low intersection index and high stress level were excluded. Good couples for

  5. Scaffold Library for Tissue Engineering: A Geometric Evaluation

    Directory of Open Access Journals (Sweden)

    Nattapon Chantarapanich

    2012-01-01

    Full Text Available Tissue engineering scaffold is a biological substitute that aims to restore, to maintain, or to improve tissue functions. Currently available manufacturing technology, that is, additive manufacturing is essentially applied to fabricate the scaffold according to the predefined computer aided design (CAD model. To develop scaffold CAD libraries, the polyhedrons could be used in the scaffold libraries development. In this present study, one hundred and nineteen polyhedron models were evaluated according to the established criteria. The proposed criteria included considerations on geometry, manufacturing feasibility, and mechanical strength of these polyhedrons. CAD and finite element (FE method were employed as tools in evaluation. The result of evaluation revealed that the close-cellular scaffold included truncated octahedron, rhombicuboctahedron, and rhombitruncated cuboctahedron. In addition, the suitable polyhedrons for using as open-cellular scaffold libraries included hexahedron, truncated octahedron, truncated hexahedron, cuboctahedron, rhombicuboctahedron, and rhombitruncated cuboctahedron. However, not all pore size to beam thickness ratios (PO : BT were good for making the open-cellular scaffold. The PO : BT ratio of each library, generating the enclosed pore inside the scaffold, was excluded to avoid the impossibility of material removal after the fabrication. The close-cellular libraries presented the constant porosity which is irrespective to the different pore sizes. The relationship between PO : BT ratio and porosity of open-cellular scaffold libraries was displayed in the form of Logistic Power function. The possibility of merging two different types of libraries to produce the composite structure was geometrically evaluated in terms of the intersection index and was mechanically evaluated by means of FE analysis to observe the stress level. The couples of polyhedrons presenting low intersection index and high stress

  6. Electrospun nanofiber scaffolds: engineering soft tissues

    International Nuclear Information System (INIS)

    Kumbar, S G; Nukavarapu, S P; Laurencin, C T; James, R

    2008-01-01

    Electrospinning has emerged to be a simple, elegant and scalable technique to fabricate polymeric nanofibers. Pure polymers as well as blends and composites of both natural and synthetics have been successfully electrospun into nanofiber matrices. Physiochemical properties of nanofiber matrices can be controlled by manipulating electrospinning parameters to meet the requirements of a specific application. Such efforts include the fabrication of fiber matrices containing nanofibers, microfibers, combination of nano-microfibers and also different fiber orientation/alignments. Polymeric nanofiber matrices have been extensively investigated for diversified uses such as filtration, barrier fabrics, wipes, personal care, biomedical and pharmaceutical applications. Recently electrospun nanofiber matrices have gained a lot of attention, and are being explored as scaffolds in tissue engineering due to their properties that can modulate cellular behavior. Electrospun nanofiber matrices show morphological similarities to the natural extra-cellular matrix (ECM), characterized by ultrafine continuous fibers, high surface-to-volume ratio, high porosity and variable pore-size distribution. Efforts have been made to modify nanofiber surfaces with several bioactive molecules to provide cells with the necessary chemical cues and a more in vivo like environment. The current paper provides an overlook on such efforts in designing nanofiber matrices as scaffolds in the regeneration of various soft tissues including skin, blood vessel, tendon/ligament, cardiac patch, nerve and skeletal muscle

  7. Electrospun nanofiber scaffolds: engineering soft tissues

    Energy Technology Data Exchange (ETDEWEB)

    Kumbar, S G; Nukavarapu, S P; Laurencin, C T [Department of Orthopaedic Surgery, University of Virginia, VA 22908 (United States); James, R [Department of Biomedical Engineering, University of Virginia, VA 22908 (United States)], E-mail: laurencin@virginia.edu

    2008-09-01

    Electrospinning has emerged to be a simple, elegant and scalable technique to fabricate polymeric nanofibers. Pure polymers as well as blends and composites of both natural and synthetics have been successfully electrospun into nanofiber matrices. Physiochemical properties of nanofiber matrices can be controlled by manipulating electrospinning parameters to meet the requirements of a specific application. Such efforts include the fabrication of fiber matrices containing nanofibers, microfibers, combination of nano-microfibers and also different fiber orientation/alignments. Polymeric nanofiber matrices have been extensively investigated for diversified uses such as filtration, barrier fabrics, wipes, personal care, biomedical and pharmaceutical applications. Recently electrospun nanofiber matrices have gained a lot of attention, and are being explored as scaffolds in tissue engineering due to their properties that can modulate cellular behavior. Electrospun nanofiber matrices show morphological similarities to the natural extra-cellular matrix (ECM), characterized by ultrafine continuous fibers, high surface-to-volume ratio, high porosity and variable pore-size distribution. Efforts have been made to modify nanofiber surfaces with several bioactive molecules to provide cells with the necessary chemical cues and a more in vivo like environment. The current paper provides an overlook on such efforts in designing nanofiber matrices as scaffolds in the regeneration of various soft tissues including skin, blood vessel, tendon/ligament, cardiac patch, nerve and skeletal muscle.

  8. Engineered porous scaffolds for periprosthetic infection prevention

    Energy Technology Data Exchange (ETDEWEB)

    Iviglia, Giorgio, E-mail: giorgio.iviglia@polito.it [Nobil Bio Ricerche Srl, 14037 Portacomaro (Italy); Department of Applied Science and Technology, Institute of Materials Physics and Engineering, Politecnico di Torino, 10121 Torino (Italy); Cassinelli, Clara; Bollati, Daniele [Nobil Bio Ricerche Srl, 14037 Portacomaro (Italy); Baino, Francesco [Department of Applied Science and Technology, Institute of Materials Physics and Engineering, Politecnico di Torino, 10121 Torino (Italy); Torre, Elisa; Morra, Marco [Nobil Bio Ricerche Srl, 14037 Portacomaro (Italy); Vitale-Brovarone, Chiara [Department of Applied Science and Technology, Institute of Materials Physics and Engineering, Politecnico di Torino, 10121 Torino (Italy)

    2016-11-01

    Periprosthetic infection is a consequence of implant insertion procedures and strategies for its prevention involve either an increase in the rate of new bone formation or the release of antibiotics such as vancomycin. In this work we combined both strategies and developed a novel, multifunctional three-dimensional porous scaffold that was produced using hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), coupled with a pectin (PEC)-chitosan (CHIT) polyelectrolyte (PEI), and loaded with vancomycin (VCA). By this approach, a controlled vancomycin release was achieved and serial bacterial dilution test demonstrated that, after 1 week, the engineered construct still inhibits the bacterial growth. Degradation tests show an excellent behavior in a physiological and acidic environment (< 10% of mass loss). Furthermore, the PEI coating shows an anti-inflammatory response, and good cell proliferation and migration were demonstrated in vitro using osteoblast SAOS-2 cell line. This new engineered construct exhibits excellent properties both as an antibacterial material and as a stimulator of bone formation, which makes it a good candidate to contrast periprosthetic infection. - Highlights: • A novel three-dimensional ceramic scaffold was developed for infection prevention. • Pectin/chitosan coating stabilizes the degradation behavior in acidic environment. • Polyelectrolyte complex allows sustained release of vancomycin. • Inhibition of bacterial proliferation and biofilm formation was assessed. • PEI coating elicits anti-inflammatory response.

  9. Engineered porous scaffolds for periprosthetic infection prevention

    International Nuclear Information System (INIS)

    Iviglia, Giorgio; Cassinelli, Clara; Bollati, Daniele; Baino, Francesco; Torre, Elisa; Morra, Marco; Vitale-Brovarone, Chiara

    2016-01-01

    Periprosthetic infection is a consequence of implant insertion procedures and strategies for its prevention involve either an increase in the rate of new bone formation or the release of antibiotics such as vancomycin. In this work we combined both strategies and developed a novel, multifunctional three-dimensional porous scaffold that was produced using hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), coupled with a pectin (PEC)-chitosan (CHIT) polyelectrolyte (PEI), and loaded with vancomycin (VCA). By this approach, a controlled vancomycin release was achieved and serial bacterial dilution test demonstrated that, after 1 week, the engineered construct still inhibits the bacterial growth. Degradation tests show an excellent behavior in a physiological and acidic environment (< 10% of mass loss). Furthermore, the PEI coating shows an anti-inflammatory response, and good cell proliferation and migration were demonstrated in vitro using osteoblast SAOS-2 cell line. This new engineered construct exhibits excellent properties both as an antibacterial material and as a stimulator of bone formation, which makes it a good candidate to contrast periprosthetic infection. - Highlights: • A novel three-dimensional ceramic scaffold was developed for infection prevention. • Pectin/chitosan coating stabilizes the degradation behavior in acidic environment. • Polyelectrolyte complex allows sustained release of vancomycin. • Inhibition of bacterial proliferation and biofilm formation was assessed. • PEI coating elicits anti-inflammatory response.

  10. Visual cognition

    Energy Technology Data Exchange (ETDEWEB)

    Pinker, S.

    1985-01-01

    This collection of research papers on visual cognition first appeared as a special issue of Cognition: International Journal of Cognitive Science. The study of visual cognition has seen enormous progress in the past decade, bringing important advances in our understanding of shape perception, visual imagery, and mental maps. Many of these discoveries are the result of converging investigations in different areas, such as cognitive and perceptual psychology, artificial intelligence, and neuropsychology. This volume is intended to highlight a sample of work at the cutting edge of this research area for the benefit of students and researchers in a variety of disciplines. The tutorial introduction that begins the volume is designed to help the nonspecialist reader bridge the gap between the contemporary research reported here and earlier textbook introductions or literature reviews.

  11. Cognitive Systems

    DEFF Research Database (Denmark)

    The tutorial will discuss the definition of cognitive systems as the possibilities to extend the current systems engineering paradigm in order to perceive, learn, reason and interact robustly in open-ended changing environments. I will also address cognitive systems in a historical perspective...... to be modeled within a limited set of predefined specifications. There will inevitably be a need for robust decisions and behaviors in novel situations that include handling of conflicts and ambiguities based on the capability and knowledge of the artificial cognitive system. Further, there is a need...... in cognitive systems include e.g. personalized information systems, sensor network systems, social dynamics system and Web2.0, and cognitive components analysis. I will use example from our own research and link to other research activities....

  12. Cognitive remission

    DEFF Research Database (Denmark)

    Bortolato, Beatrice; Miskowiak, Kamilla W; Köhler, Cristiano A

    2016-01-01

    BACKGROUND: Cognitive dysfunction in major depressive disorder (MDD) encompasses several domains, including but not limited to executive function, verbal memory, and attention. Furthermore, cognitive dysfunction is a frequent residual manifestation in depression and may persist during the remitted...... phase. Cognitive deficits may also impede functional recovery, including workforce performance, in patients with MDD. The overarching aims of this opinion article are to critically evaluate the effects of available antidepressants as well as novel therapeutic targets on neurocognitive dysfunction in MDD....... DISCUSSION: Conventional antidepressant drugs mitigate cognitive dysfunction in some people with MDD. However, a significant proportion of MDD patients continue to experience significant cognitive impairment. Two multicenter randomized controlled trials (RCTs) reported that vortioxetine, a multimodal...

  13. Effects of inadequate maternal dietary protein:carbohydrate ratios during pregnancy on offspring immunity in pigs

    Directory of Open Access Journals (Sweden)

    Tuchscherer Margret

    2012-11-01

    Full Text Available Abstract Background Inadequate nutrition in utero may retard foetal growth and alter physiological development of offspring. This study investigated the effects of low and high protein diets fed to primiparous German Landrace sows throughout pregnancy on the immune function of their offspring at different ages. Sows were fed diets with adequate (AP, 12.1%; n = 13, low (LP, 6.5%; n = 15, or high (HP, 30%; n = 14 protein content, made isoenergetic by varying carbohydrate levels. Cortisol, total protein and immunoglobulin (IgG, IgM, IgA concentrations were measured in the blood of sows over the course of pregnancy. Cortisol, total protein, immunoglobulins, lymphocyte proliferation, immune cell counts, and cytokines were assessed in the blood of offspring at baseline and under challenging conditions (weaning; lipopolysaccharide (LPS administration. Results In sows, the LP diet increased cortisol (P P P P + cell percentage and the CD4+/CD8+ ratio increased after weaning (P P = 0.09 and HP (P P  Conclusions Our results indicate that both low and high protein:carbohydrate ratios in the diet of pregnant sows can induce short-term as well as long-lasting effects on immune competence in piglets that may have serious consequences for host defence against bacterial pathogens.

  14. Dutch healthcare professionals inadequately perceived if three- and four-year-old preschool children were overweight.

    Science.gov (United States)

    Bocca, Gianni; Corpeleijn, Eva; Broens, Jasper; Stolk, Ronald P; Sauer, Pieter J

    2016-10-01

    We studied whether healthcare professionals adequately perceived if preschool children were overweight and whether this was influenced by their own body mass index (BMI). We sent 716 Dutch healthcare professionals questionnaires containing seven pictures and seven sketches of three- and four-year-old children showing body weights from underweight to morbidly obese. The professionals rated the pictures on a five-point scale from too heavy to too light and chose the sketch that they felt best depicted the child's body shape. They also reported their own height and weight and their BMI was calculated. Of the 716 questionnaires, 346 (48.3%) were returned with complete information and analysed. Healthcare professionals mostly chose sketches that showed children as being lighter than they really were. Depending on their own BMI group, the overweight child was perceived as having a normal weight by 74-79% of the healthcare professionals. The obese children were rated correctly by 44-52% of the professionals, but 14-15% said their weight was normal. The morbidly obese child was adequately assessed by 93-98% of the professionals. Healthcare professionals inadequately perceived whether three- and four-year-old children were overweight and this may have hindered early interventions, leading to overweight children becoming overweight adolescents. ©2015 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  15. Efficacy of obeticholic acid in patients with primary biliary cirrhosis and inadequate response to ursodeoxycholic acid.

    Science.gov (United States)

    Hirschfield, Gideon M; Mason, Andrew; Luketic, Velimir; Lindor, Keith; Gordon, Stuart C; Mayo, Marlyn; Kowdley, Kris V; Vincent, Catherine; Bodhenheimer, Henry C; Parés, Albert; Trauner, Michael; Marschall, Hanns-Ulrich; Adorini, Luciano; Sciacca, Cathi; Beecher-Jones, Tessa; Castelloe, Erin; Böhm, Olaf; Shapiro, David

    2015-04-01

    We evaluated the efficacy and safety of obeticholic acid (OCA, α-ethylchenodeoxycholic acid) in a randomized controlled trial of patients with primary biliary cirrhosis who had an inadequate response to ursodeoxycholic acid therapy. We performed a double-blind study of 165 patients with primary biliary cirrhosis (95% women) and levels of alkaline phosphatase (ALP) 1.5- to 10-fold the upper limit of normal. Patients were randomly assigned to groups given 10 mg, 25 mg, or 50 mg doses of OCA or placebo, once daily for 3 months. Patients maintained their existing dose of ursodeoxycholic acid throughout the study. The primary outcome was change in level of ALP from baseline (day 0) until the end of the study (day 85 or early termination). We also performed an open-label extension of the trial in which 78 patients were enrolled and 61 completed the first year. OCA was superior to placebo in achieving the primary end point. Subjects given OCA had statistically significant relative reductions in mean ALP from baseline to the end of the study (P ursodeoxycholic acid. The incidence and severity of pruritus were lowest among patients who received 10 mg/d OCA. Biochemical responses to OCA were maintained in a 12-month open-label extension trial. ClinicalTrials.gov ID: NCT00550862. Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.

  16. Public health safety and environment in inadequate hospital and healthcare settings: a review.

    Science.gov (United States)

    Baguma, D

    2017-03-01

    Public health safety and environmental management are concerns that pose challenges worldwide. This paper briefly assesses a selected impact of the environment on public health. The study used an assessment of environmental mechanism to analyse the underlying different pathways in which the health sector is affected in inadequate hospital and health care settings. We reviewed the limited available evidence of the association between the health sector and the environment, and the likely pathways through which the environment influences health. The paper also models the use of private health care as a function of costs and benefits relative to public care and no care. The need to enhancing policies to improve the administration of health services, strengthening interventions on environment using international agreements, like Rio Conventions, including measures to control hospital-related infection, planning for human resources and infrastructure construction development have linkage to improve environment care and public health. The present study findings partly also demonstrate the influence of demand for health on the environment. The list of possible interventions includes enhancing policies to improve the administration of health services, strengthening Rio Conventions implementation on environmental concerns, control of environmental hazards and public health. Copyright © 2016 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

  17. Evaluation of inadequate anti-retroviral treatment in patients with HIV/AIDS

    Directory of Open Access Journals (Sweden)

    Leonardo Carvalho da Fonseca

    2012-04-01

    Full Text Available INTRODUCTION: Since the emergence of antiretroviral therapy, the survival of patients infected with human immunodeficiency virus has increased. Non-adherence to this therapy is directly related to treatment failure, which allows the emergence of resistant viral strains. METHODS: A retrospective descriptive study of the antiretroviral dispensing records of 229 patients from the Center for Health Care, University Hospital, Federal University of Juiz de Fora, Brazil, was conducted between January and December 2009. RESULTS: The study aimed to evaluate patient compliance and determine if there was an association between non-adherence and the therapy. Among these patients, 63.8% were men with an average age of 44.0 ± 9.9 years. The most used treatment was a combination of 2 nucleoside reverse transcriptase inhibitors with 1 non-nucleoside reverse transcriptase inhibitor (55.5% or with 2 protease inhibitors (28.8%. It was found that patients taking lopinavir/ritonavir with zidovudine and lamivudine had a greater frequency of inadequate treatment than those taking atazanavir with zidovudine and lamivudine (85% and 83.3%, respectively. Moreover, when the combination of zidovudine/ lamivudine was used, the patients were less compliant (χ2 = 4.468, 1 degree of freedom, p = 0.035. CONCLUSIONS: The majority of patients failed to correctly adhere to their treatment; therefore, it is necessary to implement strategies that lead to improved compliance, thus ensuring therapeutic efficacy and increased patient survival.

  18. The challenge of inadequate achievement in mathematics: Focus on a meta-approach

    Directory of Open Access Journals (Sweden)

    Kobus Maree

    2009-09-01

    Full Text Available As is the case elsewhere in the world, all stakeholders in South Africa are deeply concerned about the level and scope of underachievement in mathematics, not only at Grade 12 level, but, indeed, at University, University of Technology and Further Education and Training levels. These concerns assume a deeper dimension in light of the fact that inadequate achievement in mathematics inevitably will have a ripple effect on the academic situation in any country: inadequate achievement in mathematics precludes learners from applying for admission to sought-after fi elds of study, which, in turn, prevents numerous learners from realising their true potential and, eventually, from being happy and successful in careers that they might otherwise have been able to execute successfully. It goes without saying that inadequate achievement in mathematics will impact negatively on the overall economic situation in any country (even more so in a developing country such as South Africa. Truth being, achievement in mathematics amounts to equipping oneself with survival skills. In this article, the spotlight shifts from a narrow and outdated focus on problems that are associated with inadequate achievement in mathematics to possible solutions for this disconcerting situation and the implied challenge it raises. The focus is thus on three levels that collectively underpin and impact on achievement in mathematics, viz. the macro level, the meso level and the micro level. The macro level refers mainly to the input by the national government (and, by default, the National Department of Education. In the fi rst instance, it is the responsibility of the state to provide adequate schooling facilities for all learners, irrespective of where they fi nd themselves. Furthermore, it is the duty of the state to ensure that every learner has access to basic facilities, including food, water, sanitation and housing. The state (via the National Department of Education is also

  19. Fossil fuel subsidy removal and inadequate public power supply: Implications for businesses

    International Nuclear Information System (INIS)

    Bazilian, Morgan; Onyeji, Ijeoma

    2012-01-01

    We briefly consider the impact of fossil fuel subsidy removal policies in the context of inadequate power supply, with a focus on the implications for businesses. In doing so, we utilize the case of the early 2012 fuel subsidy removal in Nigeria. The rationale for such subsidy-removal policies is typically informed by analysis showing that they lead to an economically inefficient allocation of resources and market distortions, while often failing to meet intended objectives. However, often the realities of infrastructural and institutional deficiencies are not appropriately factored into the decision-making process. Businesses in many developing countries, already impaired by the high cost of power supply deficiencies, become even less competitive on an unsubsidized basis. We find that justifications for removal often do not adequately reflect the specific environments of developing country economies, resulting in poor recommendations – or ineffective policy. - Highlights: ► We consider the impact of fuel subsidy removal in the context of energy poverty. ► Calls for subsidy removal often do not reflect the developing country realities. ► Businesses impaired by power supply deficiencies, become even less competitive.

  20. The impact of an inadequate municipal water system on the residents of Chinhoyi town, Zimbabwe.

    Science.gov (United States)

    Schwartz, U; Siziya, S; Tshimanga, M; Barduagni, P; Chauke, T L

    1999-06-01

    To assess the use and impact of the water reticulation system in Chinhoyi on its residents. Cross sectional and case series studies. Chinhoyi town. 600 Chinhoyi residents. Practices and perceptions of Chinhoyi residents on the water system, and distribution of water-related diseases per area of residence. Out of 600 respondents, 565 (99.3%) had access to piped water and 558 (98.0%) to flush toilets. Breakdowns of water supply and functioning of toilet facility were reported by 308 (77.0%) and 110 (28.0%) respondents in the previous six months, respectively. Main complaints of Chinhoyi residents were about low water quality (36.2%), inadequate sewage system (31.3%) and environmental pollution (26.5%). Cases of water-related diseases were not associated with natural water bodies. Chinhoyi residents have good access to the municipal water and an adequate sanitation system. However, low quality of the water, frequent system breakdowns and the degradation and loss of amenity of the environment impair their quality of life.

  1. Suboptimal Iodine Concentration in Breastmilk and Inadequate Iodine Intake among Lactating Women in Norway.

    Science.gov (United States)

    Henjum, Sigrun; Lilleengen, Anne Marie; Aakre, Inger; Dudareva, Anna; Gjengedal, Elin Lovise Folven; Meltzer, Helle Margrete; Brantsæter, Anne Lise

    2017-06-22

    Breastfed infants depend on sufficient maternal iodine intake for optimal growth and neurological development. Despite this, few studies have assessed iodine concentrations in human milk and there is currently no published data on iodine status among lactating women in Norway. The aim of this study was to assess iodine concentrations in breast milk (BMIC) in lactating women and estimate iodine intake. Five Mother and Child Health Centres in Oslo were randomly selected during 2016, and 175 lactating women between 2nd and 28th weeks postpartum participated. Each of the women provided four breastmilk samples which were pooled and analysed for iodine concentrations. Participants also provided information on iodine intake from food and supplements covering the last 24 h and the habitual iodine intake (food frequency questionnaire). The median (p25, p75 percentiles) BMIC was 68 (45, 98) µg/L and 76% had BMIC food (p25, p75) was 121 (82, 162) µg/day and the total intake (food and supplements) was 134 (95, 222) µg/day. The majority of lactating women had suboptimal BMIC and inadequate intake of iodine from food and supplements.

  2. Factors associated with inadequate receipt of components and use of antenatal care services in Nigeria: a population-based study.

    Science.gov (United States)

    Agho, Kingsley E; Ezeh, Osita K; Ogbo, Felix A; Enoma, Anthony I; Raynes-Greenow, Camille

    2018-05-01

    Antenatal care (ANC) is an essential intervention to improve maternal and child health. In Nigeria, no population-based studies have investigated predictors of poor receipt of components and uptake of ANC at the national level to inform targeted maternal health initiatives. This study aimed to examine factors associated with inadequate receipt of components and use of ANC in Nigeria. The study used information on 20 405 singleton live-born infants of the mothers from the 2013 Nigeria Demographic and Health Survey. Multivariable logistic regression analyses that adjusted for cluster and survey weights were used to determine potential factors associated with inadequate receipt of components and use of ANC. The prevalence of underutilization and inadequate components of ANC were 47.5% (95% CI: 45.2 to 49.9) and 92.6% (95% CI: 91.8 to 93.2), respectively. Common risk factors for underutilization and inadequate components of ANC in Nigeria included residence in rural areas, no maternal education, maternal unemployment, long distance to health facilities and less maternal exposure to the media. Other risk factors for underutilization of ANC were home births and low household wealth. The study suggests that underutilization and inadequate receipt of the components of ANC were associated with amenable factors in Nigeria. Subsidized maternal services and well-guided health educational messages or financial support from the government will help to improve uptake of ANC services.

  3. Racial and Social Class Differences in How Parents Respond to Inadequate Achievement: Consequences for Children's Future Achievement.

    Science.gov (United States)

    Robinson, Keith; Harris, Angel L

    2013-12-01

    Despite numerous studies on parental involvement in children's academic schooling, there is a dearth of knowledge on how parents respond specifically to inadequate academic performance. This study examines whether 1) racial differences exist in parenting philosophy for addressing inadequate achievement, 2) social class has implications for parenting philosophy, and 3) parents' philosophies are consequential for children's academic achievement. Using data from the Child Development Supplement (N=1041) to the Panel Study of Income Dynamics, we sort parents into two categories-those whose parenting repertoires for addressing poor achievement include punitive responses and those whose repertoires do not. We then determine whether racial differences exist between these categories and how various responses within the aforementioned categories are related to students' academic achievement. The findings show that white and black parents have markedly different philosophies on how to respond to inadequate performance, and these differences appear to impact children's achievement in dramatically different ways. Educators and policy makers should pay particular attention to how parents respond to inadequate achievement as imploring parents of inadequately performing students to be more involved without providing them with some guidance might exacerbate the problem.

  4. Factors affecting feeling-of-knowing in a medical intelligent tutoring system: the role of immediate feedback as a metacognitive scaffold.

    Science.gov (United States)

    El Saadawi, Gilan M; Azevedo, Roger; Castine, Melissa; Payne, Velma; Medvedeva, Olga; Tseytlin, Eugene; Legowski, Elizabeth; Jukic, Drazen; Crowley, Rebecca S

    2010-03-01

    Previous studies in our laboratory have shown the benefits of immediate feedback on cognitive performance for pathology residents using an intelligent tutoring system (ITS) in pathology. In this study, we examined the effect of immediate feedback on metacognitive performance, and investigated whether other metacognitive scaffolds will support metacognitive gains when immediate feedback is faded. Twenty-three participants were randomized into intervention and control groups. For both groups, periods working with the ITS under varying conditions were alternated with independent computer-based assessments. On day 1, a within-subjects design was used to evaluate the effect of immediate feedback on cognitive and metacognitive performance. On day 2, a between-subjects design was used to compare the use of other metacognitive scaffolds (intervention group) against no metacognitive scaffolds (control group) on cognitive and metacognitive performance, as immediate feedback was faded. Measurements included learning gains (a measure of cognitive performance), as well as several measures of metacognitive performance, including Goodman-Kruskal gamma correlation (G), bias, and discrimination. For the intervention group, we also computed metacognitive measures during tutoring sessions. Results showed that immediate feedback in an intelligent tutoring system had a statistically significant positive effect on learning gains, G and discrimination. Removal of immediate feedback was associated with decreasing metacognitive performance, and this decline was not prevented when students used a version of the tutoring system that provided other metacognitive scaffolds. Results obtained directly from the ITS suggest that other metacognitive scaffolds do have a positive effect on G and discrimination, as immediate feedback is faded. We conclude that immediate feedback had a positive effect on both metacognitive and cognitive gains in a medical tutoring system. Other metacognitive scaffolds

  5. Factors Affecting Feeling-of-knowing in a Medical Intelligent Tutoring System – the role of Immediate Feedback as a Metacognitive Scaffold

    Science.gov (United States)

    El Saadawi, Gilan M.; Azevedo, Roger; Castine, Melissa; Payne, Velma; Medvedeva, Olga; Tseytlin, Eugene; Legowski, Elizabeth; Jukic, Drazen; Crowley, Rebecca S.

    2009-01-01

    Objective Previous studies in our laboratory have shown the benefits of immediate feedback on cognitive performance for pathology residents using an Intelligent Tutoring System in Pathology. In this study, we examined the effect of immediate feedback on metacognitive performance, and investigated whether other metacognitive scaffolds will support metacognitive gains when immediate feedback is faded. Methods Twenty-three (23) participants were randomized into intervention and control groups. For both groups, periods working with the ITS under varying conditions were alternated with independent computer-based assessments. On day 1, a within-subjects design was used to evaluate the effect of immediate feedback on cognitive and metacognitive performance. On day 2, a between-subjects design was used to compare the use of other metacognitive scaffolds (intervention group) against no metacognitive scaffolds (control group) on cognitive and metacognitive performance, as immediate feedback was faded. Measurements included learning gains (a measure of cognitive performance), as well as several measures of metacognitive performance, including Goodman-Kruskal Gamma correlation (G), Bias, and Discrimination. For the intervention group, we also computed metacognitive measures during tutoring sessions. Results Results showed that immediate feedback in an intelligent tutoring system had a statistically significant positive effect on learning gains, G and discrimination. Removal of immediate feedback was associated with decreasing metacognitive performance, and this decline was not prevented when students used a version of the tutoring system that provided other metacognitive scaffolds. Results obtained directly from the ITS suggest that other metacognitive scaffolds do have a positive effect on G and Discrimination, as immediate feedback is faded. Conclusions Immediate feedback had a positive effect on both metacognitive and cognitive gains in a medical tutoring system. Other

  6. Hydrophilic PCU scaffolds prepared by grafting PEGMA and immobilizing gelatin to enhance cell adhesion and proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Changcan; Yuan, Wenjie; Khan, Musammir; Li, Qian [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Key Laboratory of Systems Bioengineering of Ministry of Education, Tianjin University, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Chemical Engineering (Tianjin) Tianjin 300072 (China); Yao, Fanglian [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Key Laboratory of Systems Bioengineering of Ministry of Education, Tianjin University, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Tianjin 300072 (China); Zhang, Wencheng, E-mail: wenchengzhang@yahoo.com [Department of Physiology and Pathophysiology, Logistics University of Chinese People' s Armed Police Force, Tianjin 300162 (China)

    2015-05-01

    Gelatin contains many functional motifs which can modulate cell specific adhesion, so we modified polycarbonate urethane (PCU) scaffold surface by immobilization of gelatin. PCU-g-gelatin scaffolds were prepared by direct immobilizing gelatins onto the surface of aminated PCU scaffolds. To increase the immobilization amount of gelatin, poly(ethylene glycol) methacrylate (PEGMA) was grafted onto PCU scaffolds by surface initiated atom transfer radical polymerization. Then, following amination and immobilization, PCU-g-PEGMA-g-gelatin scaffolds were obtained. Both modified scaffolds were characterized by chemical and biological methods. After immobilization of gelatin, the microfiber surface became rough, but the original morphology of scaffolds was maintained successfully. PCU-g-PEGMA-g-gelatin scaffolds were more hydrophilic than PCU-g-gelatin scaffolds. Because hydrophilic PEGMA and gelatin were grafted and immobilized onto the surface, the PCU-g-PEGMA-g-gelatin scaffolds showed low platelet adhesion, perfect anti-hemolytic activity and excellent cell growth and proliferation capacity. It could be envisioned that PCU-g-PEGMA-g-gelatin scaffolds might have potential applications in tissue engineering artificial scaffolds. - Graphical abstract: PCU-g-gelatin scaffolds were prepared by direct immobilizing gelatin onto the surface of aminated PCU scaffolds (method a). To increase the immobilization amount of gelatin, PEGMAs were grafted onto the scaffold surface by SI-ATRP. PCU-g-PEGMA-g-gelatin scaffolds were prepared by method b. The gelatin modified scaffolds exhibited high hydrophilicity, low platelet adhesion, perfect anti-hemolytic activity, and excellent cell adhesion and proliferation capacity. They might have potential applications as tissue engineering scaffolds for artificial blood vessels. - Highlights: • Hydrophilic scaffolds were prepared by grafting PEGMA and immobilization of gelatins. • Grafting PEGMA enhanced the immobilization amount of gelatin

  7. Bioresorbable scaffold -fourth revolution or failed revolution: Is low scaffold strut thickness the wrong target?

    Directory of Open Access Journals (Sweden)

    Sundeep Mishra

    2017-11-01

    Full Text Available Bioresorbable scaffold (BRS technology has currently fallen into disrepute because of inordinately high risk of scaffold thrombosis and post-procedure myocardial infarction. Low tensile and radial strengths of polymeric BRS contributing to improper strut embedment have been identified as major correlates of poor outcomes following BRS implantation. Magnesium has a better tensile/radial strength compared with polymeric BRS but it is still far lower than cobalt-chromium. Newers innovations utilizing alteration in polymer composition and orientation or even newer polymers have focused on attempts to reduce strut thickness but may have little effect on tensile/radial strength of finished product and therefore may not impact the BRS outcome on long run. Currently, newer generation BRS usage may be restricted to suitable low risk younger patients with proper vessel preparation and application of technique.

  8. Bioresorbable scaffold -fourth revolution or failed revolution: Is low scaffold strut thickness the wrong target?

    Science.gov (United States)

    Mishra, Sundeep

    Bioresorbable scaffold (BRS) technology has currently fallen into disrepute because of inordinately high risk of scaffold thrombosis and post-procedure myocardial infarction. Low tensile and radial strengths of polymeric BRS contributing to improper strut embedment have been identified as major correlates of poor outcomes following BRS implantation. Magnesium has a better tensile/radial strength compared with polymeric BRS but it is still far lower than cobalt-chromium. Newers innovations utilizing alteration in polymer composition and orientation or even newer polymers have focused on attempts to reduce strut thickness but may have little effect on tensile/radial strength of finished product and therefore may not impact the BRS outcome on long run. Currently, newer generation BRS usage may be restricted to suitable low risk younger patients with proper vessel preparation and application of technique. Copyright © 2017 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

  9. Enhanced bioactive scaffolds for bone tissue regeneration

    Science.gov (United States)

    Karnik, Sonali

    Bone injuries are commonly termed as fractures and they vary in their severity and causes. If the fracture is severe and there is loss of bone, implant surgery is prescribed. The response to the implant depends on the patient's physiology and implant material. Sometimes, the compromised physiology and undesired implant reactions lead to post-surgical complications. [4, 5, 20, 28] Efforts have been directed towards the development of efficient implant materials to tackle the problem of post-surgical implant failure. [ 15, 19, 24, 28, 32]. The field of tissue engineering and regenerative medicine involves the use of cells to form a new tissue on bio-absorbable or inert scaffolds. [2, 32] One of the applications of this field is to regenerate the damaged or lost bone by using stem cells or osteoprogenitor cells on scaffolds that can integrate in the host tissue without causing any harmful side effects. [2, 32] A variety of natural, synthetic materials and their combinations have been used to regenerate the damaged bone tissue. [2, 19, 30, 32, 43]. Growth factors have been supplied to progenitor cells to trigger a sequence of metabolic pathways leading to cellular proliferation, differentiation and to enhance their functionality. [56, 57] The challenge persists to supply these proteins, in the range of nano or even picograms, and in a sustained fashion over a period of time. A delivery system has yet to be developed that would mimic the body's inherent mechanism of delivering the growth factor molecules in the required amount to the target organ or tissue. Titanium is the most preferred metal for orthopedic and orthodontic implants. [28, 46, 48] Even though it has better osteogenic properties as compared to other metals and alloys, it still has drawbacks like poor integration into the surrounding host tissue leading to bone resorption and implant failure. [20, 28, 35] It also faces the problem of postsurgical infections that contributes to the implant failure. [26, 37

  10. Design, Materials, and Mechanobiology of Biodegradable Scaffolds for Bone Tissue Engineering

    Science.gov (United States)

    Velasco, Marco A.; Narváez-Tovar, Carlos A.; Garzón-Alvarado, Diego A.

    2015-01-01

    A review about design, manufacture, and mechanobiology of biodegradable scaffolds for bone tissue engineering is given. First, fundamental aspects about bone tissue engineering and considerations related to scaffold design are established. Second, issues related to scaffold biomaterials and manufacturing processes are discussed. Finally, mechanobiology of bone tissue and computational models developed for simulating how bone healing occurs inside a scaffold are described. PMID:25883972

  11. Accounting for structural compliance in nanoindentation measurements of bioceramic bone scaffolds

    Science.gov (United States)

    Juan Vivanco; Joseph E. Jakes; Josh Slane; Heidi-Lynn Ploeg

    2014-01-01

    Structural properties have been shown to be critical in the osteoconductive capacity and strength of bioactive ceramic bone scaffolds. Given the cellular foam-like structure of bone scaffolds, nanoindentation has been used as a technique to assess the mechanical properties of individual components of the scaffolds. Nevertheless, nanoindents placed on scaffolds may...

  12. Electrospinning versus knitting: two scaffolds for tisssue engineering of the aortic valve

    NARCIS (Netherlands)

    Lieshout, van M.I.; Vaz, C.M.; Rutten, M.C.M.; Peters, G.W.M.; Baaijens, F.P.T.

    2006-01-01

    Two types of scaffolds were developed for tissue engineering of the aortic valve; an electrospun valvular scaffold and a knitted valvular scaffold. These scaffolds were compared in a physiologic flow system and in a tissue-engineering process. In fibrin gel enclosed human myofibroblasts were seeded

  13. High Prevalence of Inadequate Calcium and Iron Intakes by Mexican Population Groups as Assessed by 24-Hour Recalls.

    Science.gov (United States)

    Sánchez-Pimienta, Tania G; López-Olmedo, Nancy; Rodríguez-Ramírez, Sonia; García-Guerra, Armando; Rivera, Juan A; Carriquiry, Alicia L; Villalpando, Salvador

    2016-09-01

    A National Health and Nutrition Survey (ENSANUT) conducted in Mexico in 1999 identified a high prevalence of inadequate mineral intakes in the population by using 24-h recall questionnaires. However, the 1999 survey did not adjust for within-person variance. The 2012 ENSANUT implemented a more up-to-date 24-h recall methodology to estimate usual intake distributions and prevalence of inadequate intakes. We examined the distribution of usual intakes and prevalences of inadequate intakes of calcium, iron, magnesium, and zinc in the Mexican population in groups defined according to sex, rural or urban area, geographic region of residence, and socioeconomic status (SES). We used dietary intake data obtained through the 24-h recall automated multiple-pass method for 10,886 subjects as part of ENSANUT 2012. A second measurement on a nonconsecutive day was obtained for 9% of the sample. Distributions of usual intakes of the 4 minerals were obtained by using the Iowa State University method, and the prevalence of inadequacy was estimated by using the Institute of Medicine's Estimated Average Requirement cutoff. Calcium inadequacy was 25.6% in children aged 1-4 y and 54.5-88.1% in subjects >5 y old. More than 45% of subjects >5 y old had an inadequate intake of iron. Less than 5% of children aged 12 y had inadequate intakes of magnesium, whereas zinc inadequacy ranged from <10% in children aged <12 y to 21.6% in men aged ≥20 y. Few differences were found between rural and urban areas, regions, and tertiles of SES. Intakes of calcium, iron, magnesium, and zinc are inadequate in the Mexican population, especially among adolescents and adults. These results suggest a public health concern that must be addressed. © 2016 American Society for Nutrition.

  14. Estimating the global prevalence of inadequate zinc intake from national food balance sheets: effects of methodological assumptions.

    Directory of Open Access Journals (Sweden)

    K Ryan Wessells

    Full Text Available The prevalence of inadequate zinc intake in a population can be estimated by comparing the zinc content of the food supply with the population's theoretical requirement for zinc. However, assumptions regarding the nutrient composition of foods, zinc requirements, and zinc absorption may affect prevalence estimates. These analyses were conducted to: (1 evaluate the effect of varying methodological assumptions on country-specific estimates of the prevalence of dietary zinc inadequacy and (2 generate a model considered to provide the best estimates.National food balance data were obtained from the Food and Agriculture Organization of the United Nations. Zinc and phytate contents of these foods were estimated from three nutrient composition databases. Zinc absorption was predicted using a mathematical model (Miller equation. Theoretical mean daily per capita physiological and dietary requirements for zinc were calculated using recommendations from the Food and Nutrition Board of the Institute of Medicine and the International Zinc Nutrition Consultative Group. The estimated global prevalence of inadequate zinc intake varied between 12-66%, depending on which methodological assumptions were applied. However, country-specific rank order of the estimated prevalence of inadequate intake was conserved across all models (r = 0.57-0.99, P<0.01. A "best-estimate" model, comprised of zinc and phytate data from a composite nutrient database and IZiNCG physiological requirements for absorbed zinc, estimated the global prevalence of inadequate zinc intake to be 17.3%.Given the multiple sources of uncertainty in this method, caution must be taken in the interpretation of the estimated prevalence figures. However, the results of all models indicate that inadequate zinc intake may be fairly common globally. Inferences regarding the relative likelihood of zinc deficiency as a public health problem in different countries can be drawn based on the country

  15. Electrospun Nanofiber Scaffolds with Gradations in Fiber Organization

    Science.gov (United States)

    Khandalavala, Karl; Jiang, Jiang; Shuler, Franklin D.; Xie, Jingwei

    2015-01-01

    The goal of this protocol is to report a simple method for generating nanofiber scaffolds with gradations in fiber organization and test their possible applications in controlling cell morphology/orientation. Nanofiber organization is controlled with a new fabrication apparatus that enables the gradual decrease of fiber organization in a scaffold. Changing the alignment of fibers is achieved through decreasing deposition time of random electrospun fibers on a uniaxially aligned fiber mat. By covering the collector with a moving barrier/mask, along the same axis as fiber deposition, the organizational structure is easily controlled. For tissue engineering purposes, adipose-derived stem cells can be seeded to these scaffolds. Stem cells undergo morphological changes as a result of their position on the varied organizational structure, and can potentially differentiate into different cell types depending on their locations. Additionally, the graded organization of fibers enhances the biomimicry of nanofiber scaffolds so they more closely resemble the natural orientations of collagen nanofibers at tendon-to-bone insertion site compared to traditional scaffolds. Through nanoencapsulation, the gradated fibers also afford the possibility to construct chemical gradients in fiber scaffolds, and thereby further strengthen their potential applications in fast screening of cell-materials interaction and interfacial tissue regeneration. This technique enables the production of continuous gradient scaffolds, but it also can potentially produce fibers in discrete steps by controlling the movement of the moving barrier/mask in a discrete fashion. PMID:25938562

  16. Cell-derived matrix coatings for polymeric scaffolds.

    Science.gov (United States)

    Decaris, Martin L; Binder, Bernard Y; Soicher, Matthew A; Bhat, Archana; Leach, J Kent

    2012-10-01

    Cells in culture deposit a complex extracellular matrix that remains intact following decellularization and possesses the capacity to modulate cell phenotype. The direct application of such decellularized matrices (DMs) to 3D substrates is problematic, as transport issues influence the homogeneous deposition, decellularization, and modification of DM surface coatings. In an attempt to address this shortcoming, we hypothesized that DMs deposited by human mesenchymal stem cells (MSCs) could be transferred to the surface of polymeric scaffolds while maintaining their capacity to direct cell fate. The ability of the transferred DM (tDM)-coated scaffolds to enhance the osteogenic differentiation of undifferentiated and osteogenically induced MSCs under osteogenic conditions in vitro was confirmed. tDM-coated scaffolds increased MSC expression of osteogenic marker genes (BGLAP, IBSP) and intracellular alkaline phosphatase production. In addition, undifferentiated MSCs deposited significantly more calcium when seeded onto tDM-coated scaffolds compared with control scaffolds. MSC-seeded tDM-coated scaffolds subcutaneously implanted in nude rats displayed significantly higher blood vessel density after 2 weeks compared with cells on uncoated scaffolds, but we did not observe significant differences in mineral deposition after 8 weeks. These data demonstrate that DM-coatings produced in 2D culture can be successfully transferred to 3D substrates and retain their capacity to modulate cell phenotype.

  17. Highly charged cyanine fluorophores for trafficking scaffold degradation

    International Nuclear Information System (INIS)

    Owens, Eric A; Alyabyev, Sergey; Henary, Maged; Hyun, Hoon; Kim, Soon Hee; Lee, Jeong Heon; Park, GwangLi; Ashitate, Yoshitomo; Choi, Jungmun; Hong, Gloria H; Choi, Hak Soo; Lee, Sang Jin; Khang, Gilson

    2013-01-01

    Biodegradable scaffolds have been extensively used in the field of tissue engineering and regenerative medicine. However, noninvasive monitoring of in vivo scaffold degradation is still lacking. In order to develop a real-time trafficking technique, a series of meso-brominated near-infrared (NIR) fluorophores were synthesized and conjugated to biodegradable gelatin scaffolds. Since the pentamethine cyanine core is highly lipophilic, the side chain of each fluorophore was modified with either quaternary ammonium salts or sulfonate groups. The physicochemical properties such as lipophilicity and net charge of fluorophores played a key role in the fate of NIR-conjugated scaffolds in vivo after biodegradation. The positively charged fluorophore-conjugated scaffold fragments were found in salivary glands, lymph nodes, and most of the hepatobiliary excretion route. However, halogenated fluorophores intensively accumulated into lymph nodes and the liver. Interestingly, balanced-charged gelatin scaffolds were degraded into urine in a short period of time. These results demonstrate that the noninvasive optical imaging using NIR fluorophores can be useful for the translation of biodegradable scaffolds into the clinic. (paper)

  18. Crossing kingdoms: Using decellularized plants as perfusable tissue engineering scaffolds.

    Science.gov (United States)

    Gershlak, Joshua R; Hernandez, Sarah; Fontana, Gianluca; Perreault, Luke R; Hansen, Katrina J; Larson, Sara A; Binder, Bernard Y K; Dolivo, David M; Yang, Tianhong; Dominko, Tanja; Rolle, Marsha W; Weathers, Pamela J; Medina-Bolivar, Fabricio; Cramer, Carole L; Murphy, William L; Gaudette, Glenn R

    2017-05-01

    Despite significant advances in the fabrication of bioengineered scaffolds for tissue engineering, delivery of nutrients in complex engineered human tissues remains a challenge. By taking advantage of the similarities in the vascular structure of plant and animal tissues, we developed decellularized plant tissue as a prevascularized scaffold for tissue engineering applications. Perfusion-based decellularization was modified for different plant species, providing different geometries of scaffolding. After decellularization, plant scaffolds remained patent and able to transport microparticles. Plant scaffolds were recellularized with human endothelial cells that colonized the inner surfaces of plant vasculature. Human mesenchymal stem cells and human pluripotent stem cell derived cardiomyocytes adhered to the outer surfaces of plant scaffolds. Cardiomyocytes demonstrated contractile function and calcium handling capabilities over the course of 21 days. These data demonstrate the potential of decellularized plants as scaffolds for tissue engineering, which could ultimately provide a cost-efficient, "green" technology for regenerating large volume vascularized tissue mass. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Microwell Scaffolds for the Extrahepatic Transplantation of Islets of Langerhans

    Science.gov (United States)

    Buitinga, Mijke; Truckenmüller, Roman; Engelse, Marten A.; Moroni, Lorenzo; Ten Hoopen, Hetty W. M.; van Blitterswijk, Clemens A.; de Koning, Eelco JP.; van Apeldoorn, Aart A.; Karperien, Marcel

    2013-01-01

    Allogeneic islet transplantation into the liver has the potential to restore normoglycemia in patients with type 1 diabetes. However, the suboptimal microenvironment for islets in the liver is likely to be involved in the progressive islet dysfunction that is often observed post-transplantation. This study validates a novel microwell scaffold platform to be used for the extrahepatic transplantation of islet of Langerhans. Scaffolds were fabricated from either a thin polymer film or an electrospun mesh of poly(ethylene oxide terephthalate)-poly(butylene terephthalate) (PEOT/PBT) block copolymer (composition: 4000PEOT30PBT70) and were imprinted with microwells, ∼400 µm in diameter and ∼350 µm in depth. The water contact angle and water uptake were 39±2° and 52.1±4.0 wt%, respectively. The glucose flux through electrospun scaffolds was three times higher than for thin film scaffolds, indicating enhanced nutrient diffusion. Human islets cultured in microwell scaffolds for seven days showed insulin release and insulin content comparable to those of free-floating control islets. Islet morphology and insulin and glucagon expression were maintained during culture in the microwell scaffolds. Our results indicate that the microwell scaffold platform prevents islet aggregation by confinement of individual islets in separate microwells, preserves the islet’s native rounded morphology, and provides a protective environment without impairing islet functionality, making it a promising platform for use in extrahepatic islet transplantation. PMID:23737999

  20. Novel mechanically competent polysaccharide scaffolds for bone tissue engineering

    International Nuclear Information System (INIS)

    Kumbar, S G; Toti, U S; Deng, M; James, R; Laurencin, C T; Aravamudhan, A; Harmon, M; Ramos, D M

    2011-01-01

    The success of the scaffold-based bone regeneration approach critically depends on the biomaterial's mechanical and biological properties. Cellulose and its derivatives are inherently associated with exceptional strength and biocompatibility due to their β-glycosidic linkage and extensive hydrogen bonding. This polymer class has a long medical history as a dialysis membrane, wound care system and pharmaceutical excipient. Recently cellulose-based scaffolds have been developed and evaluated for a variety of tissue engineering applications. In general porous polysaccharide scaffolds in spite of many merits lack the necessary mechanical competence needed for load-bearing applications. The present study reports the fabrication and characterization of three-dimensional (3D) porous sintered microsphere scaffolds based on cellulose derivatives using a solvent/non-solvent sintering approach for load-bearing applications. These 3D scaffolds exhibited a compressive modulus and strength in the mid-range of human trabecular bone and underwent degradation resulting in a weight loss of 10–15% after 24 weeks. A typical stress–strain curve for these scaffolds showed an initial elastic region and a less-stiff post-yield region similar to that of native bone. Human osteoblasts cultured on these scaffolds showed progressive growth with time and maintained expression of osteoblast phenotype markers. Further, the elevated expression of alkaline phosphatase and mineralization at early time points as compared to heat-sintered poly(lactic acid–glycolic acid) control scaffolds with identical pore properties affirmed the advantages of polysaccharides and their potential for scaffold-based bone regeneration.

  1. BESST--efficient scaffolding of large fragmented assemblies.

    Science.gov (United States)

    Sahlin, Kristoffer; Vezzi, Francesco; Nystedt, Björn; Lundeberg, Joakim; Arvestad, Lars

    2014-08-15

    The use of short reads from High Throughput Sequencing (HTS) techniques is now commonplace in de novo assembly. Yet, obtaining contiguous assemblies from short reads is challenging, thus making scaffolding an important step in the assembly pipeline. Different algorithms have been proposed but many of them use the number of read pairs supporting a linking of two contigs as an indicator of reliability. This reasoning is intuitive, but fails to account for variation in link count due to contig features.We have also noted that published scaffolders are only evaluated on small datasets using output from only one assembler. Two issues arise from this. Firstly, some of the available tools are not well suited for complex genomes. Secondly, these evaluations provide little support for inferring a software's general performance. We propose a new algorithm, implemented in a tool called BESST, which can scaffold genomes of all sizes and complexities and was used to scaffold the genome of P. abies (20 Gbp). We performed a comprehensive comparison of BESST against the most popular stand-alone scaffolders on a large variety of datasets. Our results confirm that some of the popular scaffolders are not practical to run on complex datasets. Furthermore, no single stand-alone scaffolder outperforms the others on all datasets. However, BESST fares favorably to the other tested scaffolders on GAGE datasets and, moreover, outperforms the other methods when library insert size distribution is wide. We conclude from our results that information sources other than the quantity of links, as is commonly used, can provide useful information about genome structure when scaffolding.

  2. Microporous dermal-like electrospun scaffolds promote accelerated skin regeneration.

    Science.gov (United States)

    Bonvallet, Paul P; Culpepper, Bonnie K; Bain, Jennifer L; Schultz, Matthew J; Thomas, Steven J; Bellis, Susan L

    2014-09-01

    The goal of this study was to synthesize skin substitutes that blend native extracellular matrix (ECM) molecules with synthetic polymers which have favorable mechanical properties. To this end, scaffolds were electrospun from collagen I (col) and poly(ɛ-caprolactone) (PCL), and then pores were introduced mechanically to promote fibroblast infiltration, and subsequent filling of the pores with ECM. A 70:30 col/PCL ratio was determined to provide optimal support for dermal fibroblast growth, and a pore diameter, 160 μm, was identified that enabled fibroblasts to infiltrate and fill pores with native matrix molecules, including fibronectin and collagen I. Mechanical testing of 70:30 col/PCL scaffolds with 160 μm pores revealed a tensile strength of 1.4 MPa, and the scaffolds also exhibited a low rate of contraction (pores. Keratinocytes formed a stratified layer on the surface of fibroblast-remodeled scaffolds, and staining for cytokeratin 10 revealed terminally differentiated keratinocytes at the apical surface. When implanted, 70:30 col/PCL scaffolds degraded within 3-4 weeks, an optimal time frame for degradation in vivo. Finally, 70:30 col/PCL scaffolds with or without 160 μm pores were implanted into full-thickness critical-sized skin defects. Relative to nonporous scaffolds or sham wounds, scaffolds with 160 μm pores induced accelerated wound closure, and stimulated regeneration of healthy dermal tissue, evidenced by a more normal-appearing matrix architecture, blood vessel in-growth, and hair follicle development. Collectively, these results suggest that microporous electrospun scaffolds are effective substrates for skin regeneration.

  3. Comparison of Vildagliptin and Pioglitazone in Korean Patients with Type 2 Diabetes Inadequately Controlled with Metformin.

    Science.gov (United States)

    Kim, Jong Ho; Kim, Sang Soo; Baek, Hong Sun; Lee, In Kyu; Chung, Dong Jin; Sohn, Ho Sang; Bae, Hak Yeon; Kim, Mi Kyung; Park, Jeong Hyun; Choi, Young Sik; Kim, Young Il; Hahm, Jong Ryeal; Lee, Chang Won; Jo, Sung Rae; Park, Mi Kyung; Lee, Kwang Jae; Kim, In Joo

    2016-06-01

    We compared the efficacies of vildagliptin (50 mg twice daily) relative to pioglitazone (15 mg once daily) as an add-on treatment to metformin for reducing glycosylated hemoglobin (HbA1c) levels in Korean patients with type 2 diabetes. The present study was a multicenter, randomized, active-controlled investigation comparing the effects of vildagliptin and pioglitazone in Korean patients receiving a stable dose of metformin but exhibiting inadequate glycemic control. Each patient underwent a 16-week treatment period with either vildagliptin or pioglitazone as an add-on treatment to metformin. The mean changes in HbA1c levels from baseline were -0.94% in the vildagliptin group and -0.6% in the pioglitazone group and the difference between the treatments was below the non-inferiority margin of 0.3%. The mean changes in postprandial plasma glucose (PPG) levels were -60.2 mg/dL in the vildagliptin group and -38.2 mg/dL in the pioglitazone group and these values significantly differed (P=0.040). There were significant decreases in the levels of total, low density lipoprotein, high density lipoprotein (HDL), and non-HDL cholesterol in the vildagliptin group but increases in the pioglitazone group. The mean change in body weight was -0.07 kg in the vildagliptin group and 0.69 kg in the pioglitazone group, which were also significantly different (P=0.002). As an add-on to metformin, the efficacy of vildagliptin for the improvement of glycemic control is not inferior to that of pioglitazone in Korean patients with type 2 diabetes. In addition, add-on treatment with vildagliptin had beneficial effects on PPG levels, lipid profiles, and body weight compared to pioglitazone.

  4. Comparison of Vildagliptin and Pioglitazone in Korean Patients with Type 2 Diabetes Inadequately Controlled with Metformin

    Directory of Open Access Journals (Sweden)

    Jong Ho Kim

    2016-04-01

    Full Text Available BackgroundWe compared the efficacies of vildagliptin (50 mg twice daily relative to pioglitazone (15 mg once daily as an add-on treatment to metformin for reducing glycosylated hemoglobin (HbA1c levels in Korean patients with type 2 diabetes.MethodsThe present study was a multicenter, randomized, active-controlled investigation comparing the effects of vildagliptin and pioglitazone in Korean patients receiving a stable dose of metformin but exhibiting inadequate glycemic control. Each patient underwent a 16-week treatment period with either vildagliptin or pioglitazone as an add-on treatment to metformin.ResultsThe mean changes in HbA1c levels from baseline were –0.94% in the vildagliptin group and –0.6% in the pioglitazone group and the difference between the treatments was below the non-inferiority margin of 0.3%. The mean changes in postprandial plasma glucose (PPG levels were –60.2 mg/dL in the vildagliptin group and –38.2 mg/dL in the pioglitazone group and these values significantly differed (P=0.040. There were significant decreases in the levels of total, low density lipoprotein, high density lipoprotein (HDL, and non-HDL cholesterol in the vildagliptin group but increases in the pioglitazone group. The mean change in body weight was –0.07 kg in the vildagliptin group and 0.69 kg in the pioglitazone group, which were also significantly different (P=0.002.ConclusionAs an add-on to metformin, the efficacy of vildagliptin for the improvement of glycemic control is not inferior to that of pioglitazone in Korean patients with type 2 diabetes. In addition, add-on treatment with vildagliptin had beneficial effects on PPG levels, lipid profiles, and body weight compared to pioglitazone.

  5. Predictors of Inadequate Linezolid Concentrations after Standard Dosing in Critically Ill Patients.

    Science.gov (United States)

    Taubert, Max; Zoller, Michael; Maier, Barbara; Frechen, Sebastian; Scharf, Christina; Holdt, Lesca-Miriam; Frey, Lorenz; Vogeser, Michael; Fuhr, Uwe; Zander, Johannes

    2016-09-01

    Adequate linezolid blood concentrations have been shown to be associated with an improved clinical outcome. Our goal was to assess new predictors of inadequate linezolid concentrations often observed in critically ill patients. Fifty-two critically ill patients with severe infections receiving standard dosing of linezolid participated in this prospective observational study. Serum samples (median, 32 per patient) were taken on four consecutive days, and total linezolid concentrations were quantified. Covariates influencing linezolid pharmacokinetics were identified by multivariate analysis and a population pharmacokinetic model. Target attainment (area under the concentration-time curve over 12 h [AUC12]/MIC ratio of >50; MIC = 2 mg/liter) was calculated for both the study patients and a simulated independent patient group (n = 67,000). Target attainment was observed for only 36% of the population on both days 1 and 4. Independent covariates related to significant decreases of linezolid concentrations included higher weight, creatinine clearance rates, and fibrinogen and antithrombin concentrations, lower concentrations of lactate, and the presence of acute respiratory distress syndrome (ARDS). Linezolid clearance was increased in ARDS patients (by 82%) and in patients with elevated fibrinogen or decreased lactate concentrations. In simulated patients, most covariates, including fibrinogen and lactate concentrations and weight, showed quantitatively minor effects on target attainment (difference of ≤9% between the first and fourth quartiles of the respective parameters). In contrast, the presence of ARDS had the strongest influence, with only ≤6% of simulated patients reaching this target. In conclusion, the presence of ARDS was identified as a new and strong predictor of insufficient linezolid concentrations, which might cause treatment failure. Insufficient concentrations might also be a major problem in patients with combined alterations of other covariate

  6. Inadequately marketing our brand: Medical student awareness of acute care surgery.

    Science.gov (United States)

    Montgomery, Stephanie C; Privette, Alicia R; Ferguson, Pamela L; Mirdamadi, Meena; Fakhry, Samir M

    2015-11-01

    Despite focused national efforts to promote acute care surgery (ACS), little is known about medical student awareness of ACS as a career choice. The impending shortage of general surgeons emphasizes the need to increase interest in this comprehensive surgical specialty. The goal of this study was to determine whether students would be more likely to consider choosing ACS if they were aware of the specialty and its benefits. A survey was distributed electronically to medical students at our institution, a Level I trauma center with an active ACS service. The survey asked questions regarding specialty choice and factors that were used in making that decision. Also included were questions regarding their familiarity and affinity for ACS. The survey was returned by 518 students. Each medical school year was proportionately represented. Twenty-one percent of the students reported surgery as their career choice; however, women were half as likely to choose surgery as men. When asked to define ACS, 23% of all students gave the correct response. Only 8.9% of the students in the preclinical years correctly defined ACS. Even in the clinical years, 54% were unaware of ACS as a specialty. Students reported that the top factors that influenced their choice were controllable lifestyle, predictable schedule, and a positive medical school role model. When asked to identify what would make ACS appealing, a 50-hour work week was deemed most influential. When given the definition of ACS with approximate pay and on-call hours, 41.5% of the students and 75% of those interested in surgery would be likely to choose ACS as a career. This study highlights that awareness of ACS as a specialty is lacking. This may reflect inadequate marketing of our "brand" both locally and nationally. Focused efforts at familiarizing students with ACS and increased role modeling may increase interest in ACS.

  7. Primary iris claw IOL retrofixation with intravitreal triamcinolone acetonide in cases of inadequate capsular support.

    Science.gov (United States)

    Kelkar, Aditya; Shah, Rachana; Vasavda, Viraj; Kelkar, Jai; Kelkar, Shreekant

    2018-02-01

    To assess the outcomes and analyze complication rates following primary iris claw IOL retrofixation with intravitreal triamcinolone acetonide. This is a retrospective interventional case series. Patients with poor capsular support-diagnosed preoperatively or owing to intraoperative complications-were treated with iris claw IOL retrofixation with intravitreal triamcinolone acetonide. The data were retrospectively analyzed. 104 eyes of 102 patients with poor capsular support who underwent the procedure between 2010 and 2013 were analyzed. The minimum follow-up period was 12 months (ranging from 12 to 36 months). Iris claw IOL was implanted in-traumatic subluxated cataracts-24 cases (23.07%), non-traumatic subluxated cataracts in 16 cases (15.38%), or as a complication of cataract surgery-intraoperative posterior capsular rent in 48 cases (46.15%) and intraoperative nucleus drop in 16 cases (15.38%). The final mean best-corrected logMAR visual acuity improved from 1.36 ± 0.64 preoperatively to 0.36 ± 0.32 at 1-year follow-up. Complications included pupil ovalization in 11 cases (10.57%), transient elevation in intraocular pressure in 7 eyes (6.73%), postoperative hypotony in 5 eyes (4.80%), cystoid macular edema in 2 eyes (1.92%), retinal detachment in 1 eye (0.96%), vitreous hemorrhage in 1 eye (0.96%), and hyphema in 1 eye (0.96%). Primary iris claw IOL retrofixation provided excellent alternative in patients with inadequate capsular support. The visual outcomes were good along with favorable rates of complications. The addition of triamcinolone acetonide helps in reducing the chances of cystoid macular edema.

  8. Nanoengineered Carbon Scaffolds for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, A. D.; Hudson, J. L.; Fan, H.; Booker, R.; Simpson, L. J.; O' Neill, K. J.; Parilla, P. A.; Heben, M. J.; Pasquali, M.; Kittrell, C.; Tour, J. M.

    2009-01-01

    Single-walled carbon nanotube (SWCNT) fibers were engineered to become a scaffold for the storage of hydrogen. Carbon nanotube fibers were swollen in oleum (fuming sulfuric acid), and organic spacer groups were covalently linked between the nanotubes using diazonium functionalization chemistry to provide 3-dimensional (3-D) frameworks for the adsorption of hydrogen molecules. These 3-D nanoengineered fibers physisorb twice as much hydrogen per unit surface area as do typical macroporous carbon materials. These fiber-based systems can have high density, and combined with the outstanding thermal conductivity of carbon nanotubes, this points a way toward solving the volumetric and heat-transfer constraints that limit some other hydrogen-storage supports.

  9. Polymer scaffold degradation control via chemical control

    Science.gov (United States)

    Hedberg-Dirk, Elizabeth L.; Dirk, Shawn; Cicotte, Kirsten

    2016-01-05

    A variety of polymers and copolymers suitable for use as biologically compatible constructs and, as a non-limiting specific example, in the formation of degradable tissue scaffolds as well methods for synthesizing these polymers and copolymers are described. The polymers and copolymers have degradation rates that are substantially faster than those of previously described polymers suitable for the same uses. Copolymers having a synthesis route which enables one to fine tune the degradation rate by selecting the specific stoichiometry of the monomers in the resulting copolymer are also described. The disclosure also provides a novel synthesis route for maleoyl chloride which yields monomers suitable for use in the copolymer synthesis methods described herein.

  10. Using Polymeric Scaffolds for Vascular Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Alida Abruzzo

    2014-01-01

    Full Text Available With the high occurrence of cardiovascular disease and increasing numbers of patients requiring vascular access, there is a significant need for small-diameter (<6 mm inner diameter vascular graft that can provide long-term patency. Despite the technological improvements, restenosis and graft thrombosis continue to hamper the success of the implants. Vascular tissue engineering is a new field that has undergone enormous growth over the last decade and has proposed valid solutions for blood vessels repair. The goal of vascular tissue engineering is to produce neovessels and neoorgan tissue from autologous cells using a biodegradable polymer as a scaffold. The most important advantage of tissue-engineered implants is that these tissues can grow, remodel, rebuild, and respond to injury. This review describes the development of polymeric materials over the years and current tissue engineering strategies for the improvement of vascular conduits.

  11. Inadequate-1D and dynamic NMR of mesoion 3-phenyl-1-thio-2,3,4-triazole-5-methylides; INADEQUATE-1D i dynamiczny NMR mezojonowych 3-fenylo-1-tio-2,3,4-triazolo-5-metylidow

    Energy Technology Data Exchange (ETDEWEB)

    Bocian, W.; Stefaniak, L. [Inst. Chemii Organicznej, Polska Akademia Nauk, Warsaw (Poland)

    1994-12-31

    The chemical shifts and coupling constants have been measured in series of mesoionic triazoles by means of inadequate atoms and dynamic NMR techniques. The electronic structure and other parameters of C5-C6 chemical bond in different derivatives of mesoionic 3-phenyl-1-thio-2,3,4-triazole-5 methyls have been determined. 14 refs, 3 figs, 2 tabs.

  12. Investigating the Effect of Scaffolding in Modern Game Design

    DEFF Research Database (Denmark)

    Jensen, Kasper Halkjær; Kraus, Martin

    2017-01-01

    of not knowing what to do. This paper investigates the effects that scaffolding in games has on players’ experience of a game. To this end, a custom game was designed and implemented that contained a number of different scenarios with different types of scaffolding. This was used to conduct an experiment on 18......Nowadays, game developers are much more focused on providing players with short-term rewards for overcoming challenges than they have been previously. This has resulted in a lot of games having more scaffolding to teach the players what to do, so they don’t quit the games in frustration...

  13. Nerve regeneration using tubular scaffolds from biodegradable polyurethane.

    Science.gov (United States)

    Hausner, T; Schmidhammer, R; Zandieh, S; Hopf, R; Schultz, A; Gogolewski, S; Hertz, H; Redl, H

    2007-01-01

    In severe nerve lesion, nerve defects and in brachial plexus reconstruction, autologous nerve grafting is the golden standard. Although, nerve grafting technique is the best available approach a major disadvantages exists: there is a limited source of autologous nerve grafts. This study presents data on the use of tubular scaffolds with uniaxial pore orientation from experimental biodegradable polyurethanes coated with fibrin sealant to regenerate a 8 mm resected segment of rat sciatic nerve. Tubular scaffolds: prepared by extrusion of the polymer solution in DMF into water coagulation bath. The polymer used for the preparation of tubular scaffolds was a biodegradable polyurethane based on hexamethylene diisocyanate, poly(epsilon-caprolactone) and dianhydro-D-sorbitol. EXPERIMENTAL MODEL: Eighteen Sprague Dawley rats underwent mid-thigh sciatic nerve transection and were randomly assigned to two experimental groups with immediate repair: (1) tubular scaffold, (2) 180 degrees rotated sciatic nerve segment (control). Serial functional measurements (toe spread test, placing tests) were performed weekly from 3rd to 12th week after nerve repair. On week 12, electrophysiological assessment was performed. Sciatic nerve and scaffold/nerve grafts were harvested for histomorphometric analysis. Collagenic connective tissue, Schwann cells and axons were evaluated in the proximal nerve stump, the scaffold/nerve graft and the distal nerve stump. The implants have uniaxially-oriented pore structure with a pore size in the range of 2 micorm (the pore wall) and 75 x 700 microm (elongated pores in the implant lumen). The skin of the tubular implants was nonporous. Animals which underwent repair with tubular scaffolds of biodegradable polyurethanes coated with diluted fibrin sealant had no significant functional differences compared with the nerve graft group. Control group resulted in a trend-wise better electrophysiological recovery but did not show statistically significant

  14. Embodying cognition

    DEFF Research Database (Denmark)

    Martiny, Kristian Møller Moltke; Aggerholm, Kenneth

    2016-01-01

    During the last decades, research on cognition has undergone a reformation, which is necessary to take into account when evaluating the cognitive and behavioural aspects of therapy. This reformation is due to the research programme called Embodied Cognition (EC). Although EC may have become...... the theoretical authority in current cognitive science, there are only sporadic examples of EC-based therapy, and no established framework. We aim to build such a framework on the aims, methods and techniques of the current third-wave of CBT. There appears to be a possibility for cross-fertilization between EC...... and CBT that could contribute to the development of theory and practice for both of them. We present a case-study of an EC-based model of intervention for working with self-control in cerebral palsy.We centre the results of the study and its discussion on how we should understand and work with self...

  15. Environmental Cognition.

    Science.gov (United States)

    Evans, Gary W.

    1980-01-01

    Research is reviewed on human spatial cognition in real, everyday settings and is organized into five empirical categories: age, familiarity, gender, class and culture, and physical components of settings. (Author/DB)

  16. Moral Cognition

    NARCIS (Netherlands)

    Schleim, Stephan; Clausen, Jens; Levy, Neil

    2015-01-01

    Research on moral cognition is a growing and heavily multidisciplinary field. This section contains chapters addressing foundational psychological, neuroscientific, and philosophical issues of research on moral decision-making. Further- more, beyond summarizing the state of the art of their

  17. Cognitive Function

    Science.gov (United States)

    Because chemicals can adversely affect cognitive function in humans, considerable effort has been made to characterize their effects using animal models. Information from such models will be necessary to: evaluate whether chemicals identified as potentially neurotoxic by screenin...

  18. Cognitive Challenges

    Science.gov (United States)

    ... Alliance Our Story Our Vision Our Team Our Leadership Our Results Our Corporate Policies FAQs Careers Contact Us Media Store Privacy Policy Sitemap Learn Engage Donate About TSC Cognitive Challenges Approximately 45% to 60% of individuals with TSC ...

  19. Cognitive technologies

    CERN Document Server

    Mello, Alan; Figueiredo, Fabrício; Figueiredo, Rafael

    2017-01-01

    This book focuses on the next generation optical networks as well as mobile communication technologies. The reader will find chapters on Cognitive Optical Network, 5G Cognitive Wireless, LTE, Data Analysis and Natural Language Processing. It also presents a comprehensive view of the enhancements and requirements foreseen for Machine Type Communication. Moreover, some data analysis techniques and Brazilian Portuguese natural language processing technologies are also described here. .

  20. Fish cognition

    OpenAIRE

    Bshary, Redouan; Brown, Culum

    2017-01-01

    The central nervous system, and the brain in particular, is one of the most remarkable products of evolution. This system allows an individual to acquire, process, store and act on information gathered from the environment. The resulting flexibility in behavior beyond genetically coded strategies is a prime adaptation in animals. The field of animal cognition examines the underlying processes and mechanisms. Fishes are a particularly interesting group of vertebrates to study cognition for two...

  1. Visual cognition.

    Science.gov (United States)

    Cavanagh, Patrick

    2011-07-01

    Visual cognition, high-level vision, mid-level vision and top-down processing all refer to decision-based scene analyses that combine prior knowledge with retinal input to generate representations. The label "visual cognition" is little used at present, but research and experiments on mid- and high-level, inference-based vision have flourished, becoming in the 21st century a significant, if often understated part, of current vision research. How does visual cognition work? What are its moving parts? This paper reviews the origins and architecture of visual cognition and briefly describes some work in the areas of routines, attention, surfaces, objects, and events (motion, causality, and agency). Most vision scientists avoid being too explicit when presenting concepts about visual cognition, having learned that explicit models invite easy criticism. What we see in the literature is ample evidence for visual cognition, but few or only cautious attempts to detail how it might work. This is the great unfinished business of vision research: at some point we will be done with characterizing how the visual system measures the world and we will have to return to the question of how vision constructs models of objects, surfaces, scenes, and events. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Formation of Neural Networks in 3D Scaffolds Fabricated by Means of Laser Microstereolithography.

    Science.gov (United States)

    Vedunova, M V; Timashev, P S; Mishchenko, T A; Mitroshina, E V; Koroleva, A V; Chichkov, B N; Panchenko, V Ya; Bagratashvili, V N; Mukhina, I V

    2016-08-01

    We developed and tested new 3D scaffolds for neurotransplantation. Scaffolds of predetermined architectonic were prepared using microstereolithography technique. Scaffolds were highly biocompatible with the nervous tissue cells. In vitro studies showed that the material of fabricated scaffolds is not toxic for dissociated brain cells and promotes the formation of functional neural networks in the matrix. These results demonstrate the possibility of fabrication of tissue-engineering constructs for neurotransplantation based on created scaffolds.

  3. Striving for Disciplinary Literacy Instruction: Cognitive Tools in a World History Course

    Science.gov (United States)

    Girard, Brian; Harris, Lauren McArthur

    2012-01-01

    The authors present a case study of a world history teacher's mediation of her students' world historical thinking and writing through unit-level cognitive tools. They analyze both scaffolding and disciplinary tools that the teacher constructed for her students in order to improve their world historical thinking, and the degree to which the…

  4. Cognitive Apprenticeship as an Instructional Strategy for Solving Corporate Training Challenges

    Science.gov (United States)

    Chan, Peter; Miller, Ronald; Monroe, Eula

    2009-01-01

    Cognitive apprenticeship is a teaching approach proponed by social constructivist educators that scaffolds upon students' "zones of proximal development" in authentic situations. It is an effective approach used by teachers of instructional technology when teaching student practitioners. Nevertheless, implementation of instructional design…

  5. Loss of integrity of thyroid morphology and function in children born to mothers with inadequately treated Graves' disease

    NARCIS (Netherlands)

    Kempers, Marlies J. E.; van Trotsenburg, A. S. Paul; van Rijn, Rick R.; Smets, Anne M. J. B.; Smit, Bert J.; de Vijlder, Jan J. M.; Vulsma, Thomas

    2007-01-01

    Context: Central congenital hypothyroidism (CH-C) in neonates born to mothers with inadequately treated Graves' disease usually needs T-4 supplementation. The thyroid and its regulatory system have not yet been extensively studied after T-4 withdrawal, until we observed disintegrated thyroid glands

  6. Influences of Inadequate Instructional Materials and Facilities in Teaching and Learning of Electrical/Electronics Technology Education Courses

    Science.gov (United States)

    Ogbu, James E.

    2015-01-01

    This study investigated the influences of inadequate instructional materials and facilities in the teaching and learning of electrical/electronics (E/E) technology education courses. The study was guided by two research questions and two null hypotheses which were tested at 0.05 level of significance. The design employed was descriptive survey…

  7. Dialysis Hypotension : A Role for Inadequate Increase in Arginine Vasopressin Levels? A Systematic Literature Review and Meta-Analysis

    NARCIS (Netherlands)

    Ettema, Esmee M.; Zittema, Debbie; Kuipers, Johanna; Gansevoort, Ron T.; Vart, Priya; de Jong, Paul E.; Westerhuis, Ralf; Franssen, Casper F. M.

    2014-01-01

    Background: Intradialytic hypotension is a common complication of hemodialysis (HD). Some studies have suggested that inadequate arginine vasopressin (AVP) increase could play a role in the pathogenesis of intradialytic hypotension. However, AVP levels during HD and its relation to hypotension has

  8. Factors explaining inadequate prenatal care utilization by first and second generation non-western women in The Netherlands.

    NARCIS (Netherlands)

    Boerleider, A.W.; Manniën, J.; Wiegers, T.A.; Francke, A.L.; Devillé, W.L.J.M.

    2013-01-01

    Background: In many industrialized western countries non-western women constitute a substantial part of the prenatal care client population. In The Netherlands, these women have also been shown to be more likely to make inadequate use of prenatal care. Explanatory factors for this include, among

  9. Performance of the lot quality assurance sampling method compared to surveillance for identifying inadequately-performing areas in Matlab, Bangladesh.

    Science.gov (United States)

    Bhuiya, Abbas; Hanifi, S M A; Roy, Nikhil; Streatfield, P Kim

    2007-03-01

    This paper compared the performance of the lot quality assurance sampling (LQAS) method in identifying inadequately-performing health work-areas with that of using health and demographic surveillance system (HDSS) data and examined the feasibility of applying the method by field-level programme supervisors. The study was carried out in Matlab, the field site of ICDDR,B, where a HDSS has been in place for over 30 years. The LQAS method was applied in 57 work-areas of community health workers in ICDDR,B-served areas in Matlab during July-September 2002. The performance of the LQAS method in identifying work-areas with adequate and inadequate coverage of various health services was compared with those of the HDSS. The health service-coverage indicators included coverage of DPT, measles, BCG vaccination, and contraceptive use. It was observed that the difference in the proportion of work-areas identified to be inadequately performing using the LQAS method with less than 30 respondents, and the HDSS was not statistically significant. The consistency between the LQAS method and the HDSS in identifying work-areas was greater for adequately-performing areas than inadequately-performing areas. It was also observed that the field managers could be trained to apply the LQAS method in monitoring their performance in reaching the target population.

  10. Safety and efficacy of twice-daily exenatide in Taiwanese patients with inadequately controlled type 2 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Chieh-Hsiang Lu

    2013-03-01

    Conclusion: This subgroup analysis of Taiwanese patients was consistent with the overall study results, which showed that exenatide BID is superior to placebo for improving glycemic control in Asian patients with type 2 diabetes who experienced inadequate glycemic control when using oral antidiabetic therapy.

  11. Restoring nervous system structure and function using tissue engineered living scaffolds

    Institute of Scientific and Technical Information of China (English)

    Laura A Struzyna; James P Harris; Kritika S Katiyar; H Isaac Chen; D KacyCullen

    2015-01-01

    Neural tissue engineering is premised on the integration of engineered living tissue with the host nervous system to directly restore lost function or to augment regenerative capacity following ner-vous system injury or neurodegenerative disease. Disconnection of axon pathways – the long-distance ifbers connecting specialized regions of the central nervous system or relaying peripheral signals – is a common feature of many neurological disorders and injury. However, functional axonal regenera-tion rarely occurs due to extreme distances to targets, absence of directed guidance, and the presence of inhibitory factors in the central nervous system, resulting in devastating effects on cognitive and sensorimotor function. To address this need, we are pursuing multiple strategies using tissue engi-neered “living scaffolds”, which are preformed three-dimensional constructs consisting of living neural cells in a deifned, often anisotropic architecture. Living scaffolds are designed to restore function by serving as a living labeled pathway for targeted axonal regeneration – mimicking key developmental mechanisms– or by restoring lost neural circuitry via direct replacement of neurons and axonal tracts. We are currently utilizing preformed living scaffolds consisting of neuronal clusters spanned by long axonal tracts as regenerative bridges to facilitate long-distance axonal regeneration and for targeted neurosurgical reconstruction of local circuits in the brain. Although there are formidable challenges in preclinical and clinical advancement, these living tissue engineered constructs represent a promising strategy to facilitate nervous system repair and functional recovery.

  12. Development of keratin–chitosan–gelatin composite scaffold for soft tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Kakkar, Prachi [Central Leather Research Institute (Council of Scientific and Industrial Research), Adyar, Chennai 600020 (India); Verma, Sudhanshu; Manjubala, I. [Biomedical Engineering Division, School of Bio Sciences and Technology, VIT University, Vellore 632014 (India); Madhan, B., E-mail: bmadhan76@yahoo.co.in [Central Leather Research Institute (Council of Scientific and Industrial Research), Adyar, Chennai 600020 (India)

    2014-12-01

    Keratin has gained much attention in the recent past as a biomaterial for wound healing owing to its biocompatibility, biodegradability, intrinsic biological activity and presence of cellular binding motifs. In this paper, a novel biomimetic scaffold containing keratin, chitosan and gelatin was prepared by freeze drying method. The prepared keratin composite scaffold had good structural integrity. Fourier Transform Infrared (FTIR) spectroscopy showed the retention of the native structure of individual biopolymers (keratin, chitosan, and gelatin) used in the scaffold. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) results revealed a high thermal denaturation temperature of the scaffold (200–250 °C). The keratin composite scaffold exhibited tensile strength (96 kPa), compression strength (8.5 kPa) and water uptake capacity (> 1700%) comparable to that of a collagen scaffold, which was used as control. The morphology of the keratin composite scaffold observed using a Scanning Electron Microscope (SEM) exhibited good porosity and interconnectivity of pores. MTT assay using NIH 3T3 fibroblast cells demonstrated that the cell viability of the keratin composite scaffold was good. These observations suggest that the keratin–chitosan–gelatin composite scaffold is a promising alternative biomaterial for tissue engineering applications. - Highlights: • Fabrication of novel Keratin-Chitosan-Gelatin composite scaffold • Keratin composite scaffold shows excellent water uptake capacity and porosity • Keratin composite scaffold shows good thermal and physical stability • Biocompatibility of the developed scaffold is comparable to collagen scaffolds • Developed scaffold is a promising material for soft tissue engineering applications.

  13. Characterization of Mechanical Properties of Tissue Scaffolds by Phase Contrast Imaging and Finite Element Modeling.

    Science.gov (United States)

    Bawolin, Nahshon K; Dolovich, Allan T; Chen, Daniel X B; Zhang, Chris W J

    2015-08-01

    In tissue engineering, the cell and scaffold approach has shown promise as a treatment to regenerate diseased and/or damaged tissue. In this treatment, an artificial construct (scaffold) is seeded with cells, which organize and proliferate into new tissue. The scaffold itself biodegrades with time, leaving behind only newly formed tissue. The degradation qualities of the scaffold are critical during the treatment period, since the change in the mechanical properties of the scaffold with time can influence cell behavior. To observe in time the scaffold's mechanical properties, a straightforward method is to deform the scaffold and then characterize scaffold deflection accordingly. However, experimentally observing the scaffold deflection is challenging. This paper presents a novel study on characterization of mechanical properties of scaffolds by phase contrast imaging and finite element modeling, which specifically includes scaffold fabrication, scaffold imaging, image analysis, and finite elements (FEs) modeling of the scaffold mechanical properties. The innovation of the work rests on the use of in-line phase contrast X-ray imaging at 20 KeV to characterize tissue scaffold deformation caused by ultrasound radiation forces and the use of the Fourier transform to identify movement. Once deformation has been determined experimentally, it is then compared with the predictions given by the forward solution of a finite element model. A consideration of the number of separate loading conditions necessary to uniquely identify the material properties of transversely isotropic and fully orthotropic scaffolds is also presented, along with the use of an FE as a form of regularization.

  14. The inadequate liability and compensation regime for damage caused by nuclear activities

    International Nuclear Information System (INIS)

    Dyke, Jon M. Van

    2010-09-01

    The specific obligation to provide restitution and compensation when nuclear activities cause injuries has been recognized repeatedly and is now certainly part of customary international law. But problems remain regarding how to measure damages, how to implement the duty to repair the injuries, and what specific obligations exist to protect neighboring states from transboundary pollution. Although some treaties exist governing liability for harm resulting from nuclear accidents, they are not adequate to protect victims and have not been widely ratified. The failure to require nuclear operators to prepare for damage that may result from accidents constitutes a subsidy to the nuclear industry and makes it difficult to compare the real costs of nuclear energy with the costs of other energy sources. This survey of settled norms and unresolved issues demonstrates that further work is needed to develop a comprehensive and authoritative regime to govern harm from nuclear activities. Although it is clear that both the operators of nuclear facilities and the states that have jurisdiction over them would be responsible to provide restitution and compensation for such harm under a strict liability regime, the types of injuries that must be compensated and the range of damages that must be covered remain subjects of controversy. Although the underlying customary international law principles (the no-harm principle and the polluter-pays principle) are clear, the actual treaties that have been drafted are inadequate and they have not been widely ratified. Victims of damage from nuclear activities would have difficulty finding a neutral tribunal in which to bring their claims and would face procedural obstacles including caps on liabilities and inappropriately short statutes of limitations as well as difficulties regarding proof of damages. The failure to develop a proper regime that would ensure full restitution and compensation for harm resulting from nuclear facilities

  15. Inadequate dietary calcium and vitamin D intakes in renal-transplant recipients in Ireland.

    LENUS (Irish Health Repository)

    Lynch, Irene T

    2012-02-03

    vitamin D intakes in adult renal-transplant patients are in many cases inadequate.

  16. Manufacture of degradable polymeric scaffolds for bone regeneration.

    Science.gov (United States)

    Ge, Zigang; Jin, Zhaoxia; Cao, Tong

    2008-06-01

    Many innovative technology platforms for promoting bone regeneration have been developed. A common theme among these is the use of scaffolds to provide mechanical support and osteoconduction. Scaffolds can be either ceramic or polymer-based, or composites of both classes of material. Both ceramics and polymers have their own merits and drawbacks, and a better solution may be to synergize the advantageous properties of both materials within composite scaffolds. In this current review, after a brief introduction of the anatomy and physiology of bone, different strategies of fabricating polymeric scaffolds for bone regeneration, including traditional and solid free-form fabrication, are critically discussed and compared, while focusing on the advantages and disadvantages of individual techniques.

  17. Put reading first: Positive effects of direct instruction and scaffolding ...

    African Journals Online (AJOL)

    Put reading first: Positive effects of direct instruction and scaffolding for ESL learners struggling with reading. ... are intended to open up for debate a topic of critical importance to the country's education system. ... AJOL African Journals Online.

  18. Protein scaffolds and higher-order complexes in synthetic biology

    NARCIS (Netherlands)

    den Hamer, A.; Rosier, B.J.H.M.; Brunsveld, L.; de Greef, T.F.A.; Ryadnov, M.; Brunsveld, L.; Suga, H.

    2017-01-01

    Interactions between proteins control molecular functions such as signalling or metabolic activity. Assembly of proteins via scaffold proteins or in higher-order complexes is a key regulatory mechanism. Understanding and functionally applying this concept requires the construction, study, and

  19. Extracellular matrix scaffolds for cartilage and bone regeneration

    NARCIS (Netherlands)

    Benders, K.E.M.; van Weeren, P.R.; Badylak, S.F.; Saris, Daniël B.F.; Dhert, W.J.A.; Malda, J.

    2013-01-01

    Regenerative medicine approaches based on decellularized extracellular matrix (ECM) scaffolds and tissues are rapidly expanding. The rationale for using ECM as a natural biomaterial is the presence of bioactive molecules that drive tissue homeostasis and regeneration. Moreover, appropriately

  20. Manufacture of degradable polymeric scaffolds for bone regeneration

    International Nuclear Information System (INIS)

    Ge Zigang; Jin Zhaoxia; Cao Tong

    2008-01-01

    Many innovative technology platforms for promoting bone regeneration have been developed. A common theme among these is the use of scaffolds to provide mechanical support and osteoconduction. Scaffolds can be either ceramic or polymer-based, or composites of both classes of material. Both ceramics and polymers have their own merits and drawbacks, and a better solution may be to synergize the advantageous properties of both materials within composite scaffolds. In this current review, after a brief introduction of the anatomy and physiology of bone, different strategies of fabricating polymeric scaffolds for bone regeneration, including traditional and solid free-form fabrication, are critically discussed and compared, while focusing on the advantages and disadvantages of individual techniques. (topical review)

  1. Novel blood protein based scaffolds for cardiovascular tissue engineering

    Directory of Open Access Journals (Sweden)

    Kuhn Antonia I.

    2016-09-01

    Full Text Available A major challenge in cardiovascular tissue engineering is the fabrication of scaffolds, which provide appropriate morphological and mechanical properties while avoiding undesirable immune reactions. In this study electrospinning was used to fabricate scaffolds out of blood proteins for cardiovascular tissue engineering. Lyophilised porcine plasma was dissolved in deionised water at a final concentration of 7.5% m/v and blended with 3.7% m/v PEO. Electrospinning resulted in homogeneous fibre morphologies with a mean fibre diameter of 151 nm, which could be adapted to create macroscopic shapes (mats, tubes. Cross-linking with glutaraldehyde vapour improved the long-term stability of protein based scaffolds in comparison to untreated scaffolds, resulting in a mass loss of 41% and 96% after 28 days of incubation in aqueous solution, respectively.

  2. Bioactive glass-based scaffolds for bone tissue engineering

    NARCIS (Netherlands)

    Will, J.; Gerhardt, L.C.; Boccaccini, A.R.

    2012-01-01

    Originally developed to fill and restore bone defects, bioactive glasses are currently also being intensively investigated for bone tissue engineering applications. In this chapter, we review and discuss current knowledge on porous bone tissue engineering scaffolds made from bioactive silicate

  3. Influence of preparation method on hydroxyapatite porous scaffolds

    Indian Academy of Sciences (India)

    Administrator

    Hydroxyapatite (HA) is extensively used in medical applications as an artificial bone because of its similarity to ... system, have been applied to fabricate HA porous scaffolds. In this work .... ceramic structured by the colloidal processing was.

  4. Biomimetic Composite Scaffold for Breast Reconstruction Following Tumor Resection

    National Research Council Canada - National Science Library

    Patrick, Jr, Charles W

    2005-01-01

    ... of life and outcomes are markedly improved. We hypothesized that a novel composite material consisting of silk fibroin and chitosan will act as a biomimetic scaffold amenable to in vivo adipogenesis. The specific aims (SAs...

  5. Alveolar bone tissue engineering using composite scaffolds for drug delivery

    Directory of Open Access Journals (Sweden)

    Tomonori Matsuno

    2010-08-01

    Full Text Available For many years, bone graft substitutes have been used to reconstruct bone defects in orthopedic and dental fields. However, synthetic bone substitutes such as hydroxyapatite or β-tricalcium phosphate have no osteoinductive or osteogenic abilities. Bone tissue engineering has also been promoted as an alternative approach to regenerating bone tissue. To succeed in bone tissue engineering, osteoconductive scaffolding biomaterials should provide a suitable environment for osteogenic cells and provide local controlled release of osteogenic growth factors. In addition, the scaffold for the bone graft substitute should biodegrade to replace the newly formed bone. Recent advances in bone tissue engineering have allowed the creation of composite scaffolds with tailored functional properties. This review focuses on composite scaffolds that consist of synthetic ceramics and natural polymers as drug delivery carriers for alveolar bone tissue engineering.

  6. PENGARUH METODE SCAFFOLDING BERBASIS KONSTRUKTIVISME TERHADAP HASIL BELAJAR MATEMATIKA

    Directory of Open Access Journals (Sweden)

    Indrawati Indrawati

    2017-01-01

    ABSTRACT This study is motivated by the fact that many students have difficulties in learning mathematics especially for junior highschool students. This study aims to know the implementation of scaffolding method based on constructivism to students’ mathematics achievement. This is an experimental study with one group pretest and posttest design. The sample were 32 students grade VIII. Data is analyzed by t-test and n-gain test. T-test result shows that sig=0,000<0,05, The average score increases 15,63 and based on N-gain test shows that students competence increases too. It means that scaffolding method based on constructivism influence students’ mathematics achievement significantly. Thus scaffolding method based on constructivism can be implemented in any instruction, because it can increase students’ achievement and students will get learning variation that can reduce boredom and motivate them to learn actively. Keywords: mathematics achievement; constructivism; scaffolding.

  7. Biological effects of functionalizing copolymer scaffolds with nanodiamond particles.

    Science.gov (United States)

    Xing, Zhe; Pedersen, Torbjorn O; Wu, Xujun; Xue, Ying; Sun, Yang; Finne-Wistrand, Anna; Kloss, Frank R; Waag, Thilo; Krueger, Anke; Steinmüller-Nethl, Doris; Mustafa, Kamal

    2013-08-01

    Significant evidence has indicated that poly(L-lactide)-co-(ɛ-caprolactone) [(poly(LLA-co-CL)] scaffolds could be one of the suitable candidates for bone tissue engineering. Oxygen-terminated nanodiamond particles (n-DP) were combined with poly(LLA-co-CL) and revealed to be positive for cell growth. In this study, we evaluated the influence of poly(LLA-co-CL) scaffolds modified by n-DP on attachment, proliferation, differentiation of bone marrow stromal cells (BMSCs) in vitro, and on bone formation using a sheep calvarial defect model. BMSCs were seeded on either poly(LLA-co-CL)- or n-DP-coated scaffolds and incubated for 1 h. Scanning electron microscopy (SEM) and fluorescence microscopy were used in addition to protein and DNA measurements to evaluate cellular attachment on the scaffolds. To determine the effect of n-DP on proliferation of BMSCs, cell/scaffold constructs were harvested after 3 days and evaluated by Bicinchoninic Acid (BCA) protein assay and SEM. In addition, the osteogenic differentiation of cells grown for 2 weeks on the various scaffolds and in a dynamic culture condition was evaluated by real-time RT-PCR. Unmodified and modified scaffolds were implanted into the calvaria of six-year-old sheep. The expression of collagen type I (COL I) and bone morphogenetic protein-2 (BMP-2) after 4 weeks as well as the formation of new bone after 12 and 24 weeks were analyzed by immunohistochemistry and histology. Scaffolds modified with n-DP supported increased cell attachment and the mRNA expression of osteopontin (OPN), bone sialoprotein (BSP), and BMP-2 were significantly increased after 2 weeks of culture. The BMSCs had spread well on the various scaffolds investigated after 3 days in the study with no significant difference in cell proliferation. Furthermore, the in vivo data revealed more positive staining of COL I and BMP-2 in relation to the n-DP-coated scaffolds after 4 weeks and presented more bone formation after 12 and 24 weeks. n

  8. Role of scaffold mean pore size in meniscus regeneration.

    Science.gov (United States)

    Zhang, Zheng-Zheng; Jiang, Dong; Ding, Jian-Xun; Wang, Shao-Jie; Zhang, Lei; Zhang, Ji-Ying; Qi, Yan-Song; Chen, Xue-Si; Yu, Jia-Kuo

    2016-10-01

    Recently, meniscus tissue engineering offers a promising management for meniscus regeneration. Although rarely reported, the microarchitectures of scaffolds can deeply influence the behaviors of endogenous or exogenous stem/progenitor cells and subsequent tissue formation in meniscus tissue engineering. Herein, a series of three-dimensional (3D) poly(ε-caprolactone) (PCL) scaffolds with three distinct mean pore sizes (i.e., 215, 320, and 515μm) were fabricated via fused deposition modeling. The scaffold with the mean pore size of 215μm significantly improved both the proliferation and extracellular matrix (ECM) production/deposition of mesenchymal stem cells compared to all other groups in vitro. Moreover, scaffolds with mean pore size of 215μm exhibited the greatest tensile and compressive moduli in all the acellular and cellular studies. In addition, the relatively better results of fibrocartilaginous tissue formation and chondroprotection were observed in the 215μm scaffold group after substituting the rabbit medial meniscectomy for 12weeks. Overall, the mean pore size of 3D-printed PCL scaffold could affect cell behavior, ECM production, biomechanics, and repair effect significantly. The PCL scaffold with mean pore size of 215μm presented superior results both in vitro and in vivo, which could be an alternative for meniscus tissue engineering. Meniscus tissue engineering provides a promising strategy for meniscus regeneration. In this regard, the microarchitectures (e.g., mean pore size) of scaffolds remarkably impact the behaviors of cells and subsequent tissue formation, which has been rarely reported. Herein, three three-dimensional poly(ε-caprolactone) scaffolds with different mean pore sizes (i.e., 215, 320, and 515μm) were fabricated via fused deposition modeling. The results suggested that the mean pore size significantly affected the behaviors of endogenous or exogenous stem/progenitor cells and subsequent tissue formation. This study furthers

  9. Predictors of Inadequate Prenatal Care in Methamphetamine-Using Mothers in New Zealand and the United States

    Science.gov (United States)

    LaGasse, Linda L.; Wouldes, Trecia A.; Arria, Amelia M.; Wilcox, Tara; Derauf, Chris; Newman, Elana; Shah, Rizwan; Smith, Lynne M.; Neal, Charles R.; Huestis, Marilyn A.; DellaGrotta, Sheri; Lester, Barry M.

    2013-01-01

    This study compared patterns of prenatal care among mothers who used methamphetamine (MA) during pregnancy and non-using mothers in the US and New Zealand (NZ), and evaluated associations among maternal drug use, child protective services (CPS) referral, and inadequate prenatal care in both countries. The sample consisted of 182 mothers in the MA-Exposed and 196 in the Comparison groups in the US, and 107 mothers in the MA-Exposed and 112 in the Comparison groups in NZ. Positive toxicology results and/or maternal report of MA use during pregnancy were used to identify MA use. Information about sociodemographics, prenatal care and prenatal substance use was collected by maternal interview. MA-use during pregnancy is associated with lower socio-economic status, single marital status, and CPS referral in both NZ and the US. Compared to their non-using counterparts, MA-using mothers in the US had significantly higher rates of inadequate prenatal care. No association was found between inadequate care and MA-use in NZ. In the US, inadequate prenatal care was associated with CPS referral, but not in NZ. Referral to CPS for drug use only composed 40 % of all referrals in the US, but only 15 % of referrals in NZ. In our study population, prenatal MA-use and CPS referral eclipse maternal sociodemographics in explanatory power for inadequate prenatal care. The predominant effect of CPS referral in the US is especially interesting, and should encourage further research on whether the US policy of mandatory reporting discourages drug-using mothers from seeking antenatal care. PMID:22588827

  10. Healthcare professionals' perceptions on the emotional impact of having an inadequate response to antidepressant medications: survey and prospective patient audit.

    Science.gov (United States)

    Mago, Rajnish; Fagiolini, Andrea; Weiller, Emmanuelle; Weiss, Catherine

    2018-01-01

    Despite the availability of effective antidepressants, about half of patients with major depressive disorder (MDD) display an inadequate response to their initial treatment. A large patient survey recently reported that 29.8% of MDD patients experiencing an inadequate treatment response felt frustrated about their medication and 19.2% were frustrated with their healthcare provider. This survey and chart audit evaluated healthcare professionals' (HCP) views on the emotional impact of having an inadequate response to antidepressant medication. HCPs who frequently treat patients with MDD completed a survey and chart audit of their MDD patients currently experiencing an inadequate response to antidepressant treatment. 287 HCPs completed 1336 chart audits. HCPs reported that 38% of their patients were trusting/accepting of their MDD medications and 41% of their patients trusted/felt confident with their healthcare provision. Conversely, HCPs reported that 11% of their patients were frustrated with their medication and 5% with their healthcare benefits. HCPs cited impact on daily life (53%) and treatment issues (lack of efficacy and side effects; 50%) as the main drivers for their patients' feelings of frustration. When HCPs recognized patients' feelings of frustration, the top concerns of the HCPs were worsening of symptoms (43%) and non-compliance (41%). This survey and chart audit highlights the emotional burden associated with inadequate responses to MDD treatment in addition to persistent symptoms. Differences between the views of the HCPs and patients are highlighted and suggest that HCPs may underestimate the full impact that having to try numerous medications has on their patients.

  11. Impact of scaffolding and question structure on the gender gap

    Directory of Open Access Journals (Sweden)

    Hillary Dawkins

    2017-09-01

    Full Text Available We address previous hypotheses about possible factors influencing the gender gap in attainment in physics. Specifically, previous studies claim that scaffolding may preferentially benefit female students, and we present some alternative conclusions surrounding this hypothesis. By taking both student attainment level and the degree of question scaffolding into account, we identify questions that exhibit real bias in favor of male students. We find that both multidimensional context and use of diagrams are common elements of such questions.

  12. Microscale versus nanoscale scaffold architecture for mesenchymal stem cell chondrogenesis.

    Science.gov (United States)

    Shanmugasundaram, Shobana; Chaudhry, Hans; Arinzeh, Treena Livingston

    2011-03-01

    Nanofiber scaffolds, produced by the electrospinning technique, have gained widespread attention in tissue engineering due to their morphological similarities to the native extracellular matrix. For cartilage repair, studies have examined their feasibility; however these studies have been limited, excluding the influence of other scaffold design features. This study evaluated the effect of scaffold design, specifically examining a range of nano to micron-sized fibers and resulting pore size and mechanical properties, on human mesenchymal stem cells (MSCs) derived from the adult bone marrow during chondrogenesis. MSC differentiation was examined on these scaffolds with an emphasis on temporal gene expression of chondrogenic markers and the pluripotent gene, Sox2, which has yet to be explored for MSCs during chondrogenesis and in combination with tissue engineering scaffolds. Chondrogenic markers of aggrecan, chondroadherin, sox9, and collagen type II were highest for cells on micron-sized fibers (5 and 9 μm) with pore sizes of 27 and 29 μm, respectively, in comparison to cells on nano-sized fibers (300 nm and 600 to 1400 nm) having pore sizes of 2 and 3 μm, respectively. Undifferentiated MSCs expressed high levels of the Sox2 gene but displayed negligible levels on all scaffolds with or without the presence of inductive factors, suggesting that the physical features of the scaffold play an important role in differentiation. Micron-sized fibers with large pore structures and mechanical properties comparable to the cartilage ECM enhanced chondrogenesis, demonstrating architectural features as well as mechanical properties of electrospun fibrous scaffolds enhance differentiation.

  13. Impact of scaffolding and question structure on the gender gap

    Science.gov (United States)

    Dawkins, Hillary; Hedgeland, Holly; Jordan, Sally

    2017-12-01

    We address previous hypotheses about possible factors influencing the gender gap in attainment in physics. Specifically, previous studies claim that scaffolding may preferentially benefit female students, and we present some alternative conclusions surrounding this hypothesis. By taking both student attainment level and the degree of question scaffolding into account, we identify questions that exhibit real bias in favor of male students. We find that both multidimensional context and use of diagrams are common elements of such questions.

  14. Tubular Scaffold with Shape Recovery Effect for Cell Guide Applications

    Directory of Open Access Journals (Sweden)

    Kazi M. Zakir Hossain

    2015-07-01

    Full Text Available Tubular scaffolds with aligned polylactic acid (PLA fibres were fabricated for cell guide applications by immersing rolled PLA fibre mats into a polyvinyl acetate (PVAc solution to bind the mats. The PVAc solution was also mixed with up to 30 wt % β-tricalcium phosphate (β-TCP content. Cross-sectional images of the scaffold materials obtained via scanning electron microscopy (SEM revealed the aligned fibre morphology along with a significant number of voids in between the bundles of fibres. The addition of β-TCP into the scaffolds played an important role in increasing the void content from 17.1% to 25.3% for the 30 wt % β-TCP loading, which was measured via micro-CT (µCT analysis. Furthermore, µCT analyses revealed the distribution of aggregated β-TCP particles in between the various PLA fibre layers of the scaffold. The compressive modulus properties of the scaffolds increased from 66 MPa to 83 MPa and the compressive strength properties decreased from 67 MPa to 41 MPa for the 30 wt % β-TCP content scaffold. The scaffolds produced were observed to change into a soft and flexible form which demonstrated shape recovery properties after immersion in phosphate buffered saline (PBS media at 37 °C for 24 h. The cytocompatibility studies (using MG-63 human osteosarcoma cell line revealed preferential cell proliferation along the longitudinal direction of the fibres as compared to the control tissue culture plastic. The manufacturing process highlighted above reveals a simple process for inducing controlled cell alignment and varying porosity features within tubular scaffolds for potential tissue engineering applications.

  15. Collagen as potential cell scaffolds for tissue engineering.

    Science.gov (United States)

    Annuar, N; Spier, R E

    2004-05-01

    Selections of collagen available commercially were tested for their biocompatibility as scaffold to promote cell growth in vitro via simple collagen fast test and cultivation of mammalian cells on the selected type of collagen. It was found that collagen type C9791 promotes the highest degree of aggregation as well as cells growth. This preliminary study also indicated potential use of collagen as scaffold in engineered tissue.

  16. A Guide to Scaffold Use in the Construction Industry

    Science.gov (United States)

    2001-01-01

    1926.451(e)(5)) and •integral prefabricated frames. (1926.451(e)(6)) What are the access requirements for employees erecting and dismantling supported...guardrails which block employee access to the cantilevered end. (6) On scaffolds where scaffold planks are abutted to create a long platform, each... abutted end shall rest on a separate support surface. This provision does not preclude the use of common support members, such as “T” sections, to support

  17. In vitro evaluation of crosslinked electrospun fish gelatin scaffolds

    International Nuclear Information System (INIS)

    Gomes, S.R.; Rodrigues, G.; Martins, G.G.; Henriques, C.M.R.; Silva, J.C.

    2013-01-01

    Gelatin from cold water fish skin was electrospun, crosslinked and investigated as a substrate for the adhesion and proliferation of cells. Gelatin was first dissolved in either water or concentrated acetic acid and both solutions were successfully electrospun. Cross-linking was achieved via three different routes: glutaraldehyde vapor, genipin and dehydrothermal treatment. Solution's properties (surface tension, electrical conductivity and viscosity) and scaffold's properties (chemical bonds, weight loss and fiber diameters) were measured. Cellular viability was analyzed culturing 3T3 fibroblasts plated on the scaffolds and grown up to 7 days. The cells were fixed and observed with SEM or stained for DNA and F-actin and observed with confocal microscopy. In all scaffolds, the cells attached and spread with varying degrees. The evaluation of cell viability showed proliferation of cells until confluence in scaffolds crosslinked by glutaraldehyde and genipin; however the rate of growth in genipin crosslinked scaffolds was slow, recovering only by day five. The results using the dehydrothermal treatment were the less satisfactory. Our results show that glutaraldehyde treated fish gelatin is the most suitable substrate, of the three studied, for fibroblast adhesion and proliferation. - Highlights: ► Electrospinning of fish gelatin dissolved in both water or concentrated acetic acid ► Glutaraldehyde, genipin and dehydrothermal treatment effectively crosslink the fish gelatin fibers ► Fibroblasts effectively adhere to and propagate on all scaffolds ► Cell population is highest for glutaraldehyde crosslinked scaffolds ► Cells exhibit more filopodia and stress fibers on glutaraldehyde crosslinked scaffolds

  18. In vitro evaluation of crosslinked electrospun fish gelatin scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, S.R. [Centro de Física e Investigação Tecnológica / Departamento de Física, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Rodrigues, G.; Martins, G.G. [Centro de Biologia Ambiental / Departamento de Biologia Animal, Faculdade de Ciências da Universidade de Lisboa, FCUL, 1749-016 Campo Grande, Lisboa (Portugal); Henriques, C.M.R. [Centro de Física e Investigação Tecnológica / Departamento de Física, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Silva, J.C., E-mail: jcs@fct.unl.pt [Centro de Física e Investigação Tecnológica / Departamento de Física, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2013-04-01

    Gelatin from cold water fish skin was electrospun, crosslinked and investigated as a substrate for the adhesion and proliferation of cells. Gelatin was first dissolved in either water or concentrated acetic acid and both solutions were successfully electrospun. Cross-linking was achieved via three different routes: glutaraldehyde vapor, genipin and dehydrothermal treatment. Solution's properties (surface tension, electrical conductivity and viscosity) and scaffold's properties (chemical bonds, weight loss and fiber diameters) were measured. Cellular viability was analyzed culturing 3T3 fibroblasts plated on the scaffolds and grown up to 7 days. The cells were fixed and observed with SEM or stained for DNA and F-actin and observed with confocal microscopy. In all scaffolds, the cells attached and spread with varying degrees. The evaluation of cell viability showed proliferation of cells until confluence in scaffolds crosslinked by glutaraldehyde and genipin; however the rate of growth in genipin crosslinked scaffolds was slow, recovering only by day five. The results using the dehydrothermal treatment were the less satisfactory. Our results show that glutaraldehyde treated fish gelatin is the most suitable substrate, of the three studied, for fibroblast adhesion and proliferation. - Highlights: ► Electrospinning of fish gelatin dissolved in both water or concentrated acetic acid ► Glutaraldehyde, genipin and dehydrothermal treatment effectively crosslink the fish gelatin fibers ► Fibroblasts effectively adhere to and propagate on all scaffolds ► Cell population is highest for glutaraldehyde crosslinked scaffolds ► Cells exhibit more filopodia and stress fibers on glutaraldehyde crosslinked scaffolds.

  19. PLDLA/PCL-T Scaffold for Meniscus Tissue Engineering.

    Science.gov (United States)

    Esposito, Andrea Rodrigues; Moda, Marlon; Cattani, Silvia Mara de Melo; de Santana, Gracy Mara; Barbieri, Juliana Abreu; Munhoz, Monique Moron; Cardoso, Túlio Pereira; Barbo, Maria Lourdes Peris; Russo, Teresa; D'Amora, Ugo; Gloria, Antonio; Ambrosio, Luigi; Duek, Eliana Aparecida de Rezende

    2013-04-01

    The inability of the avascular region of the meniscus to regenerate has led to the use of tissue engineering to treat meniscal injuries. The aim of this study was to evaluate the ability of fibrochondrocytes preseeded on PLDLA/PCL-T [poly(L-co-D,L-lactic acid)/poly(caprolactone-triol)] scaffolds to stimulate regeneration of the whole meniscus. Porous PLDLA/PCL-T (90/10) scaffolds were obtained by solvent casting and particulate leaching. Compressive modulus of 9.5±1.0 MPa and maximum stress of 4.7±0.9 MPa were evaluated. Fibrochondrocytes from rabbit menisci were isolated, seeded directly on the scaffolds, and cultured for 21 days. New Zealand rabbits underwent total meniscectomy, after which implants consisting of cell-free scaffolds or cell-seeded scaffolds were introduced into the medial knee meniscus; the negative control group consisted of rabbits that received no implant. Macroscopic and histological evaluations of the neomeniscus were performed 12 and 24 weeks after implantation. The polymer scaffold implants adapted well to surrounding tissues, without apparent rejection, infection, or chronic inflammatory response. Fibrocartilaginous tissue with mature collagen fibers was observed predominantly in implants with seeded scaffolds compared to cell-free implants after 24 weeks. Similar results were not observed in the control group. Articular cartilage was preserved in the polymeric implants and showed higher chondrocyte cell number than the control group. These findings show that the PLDLA/PCL-T 90/10 scaffold has potential for orthopedic applications since this material allowed the formation of fibrocartilaginous tissue, a structure of crucial importance for repairing injuries to joints, including replacement of the meniscus and the protection of articular cartilage from degeneration.

  20. Human cognition

    International Nuclear Information System (INIS)

    Norman, D.A.

    1982-01-01

    The study of human cognition encompasses the study of all mental phenomena, from the receipt and interpretation of sensory information to the final control of the motor system in the performance of action. The cognitive scientist examines all intermediary processes, including thought, decision making, and memory and including the effects of motivation, states of arousal and stress, the study of language, and the effects of social factors. The field therefore ranges over an enormous territory, covering all that is known or that should be known about human behavior. It is not possible to summarize the current state of knowledge about cognition with any great confidence that we know the correct answer about any aspect of the work. Nontheless, models provide good characterizations of certain aspects of the data and situations. Even if these models should prove to be incorrect, they do provide good approximate descriptions of people's behavior in some situations, and these approximations will still apply even when the underlying theories have changed. A quick description is provided of models within a number of areas of human cognition and skill and some general theoretical frameworks with which to view human cognition. The frameworks are qualitative descriptions that provide a way to view the development of more detailed, quantitative models and, most important, a way of thinking about human performance and skill

  1. Visual cognition

    Science.gov (United States)

    Cavanagh, Patrick

    2011-01-01

    Visual cognition, high-level vision, mid-level vision and top-down processing all refer to decision-based scene analyses that combine prior knowledge with retinal input to generate representations. The label “visual cognition” is little used at present, but research and experiments on mid- and high-level, inference-based vision have flourished, becoming in the 21st century a significant, if often understated part, of current vision research. How does visual cognition work? What are its moving parts? This paper reviews the origins and architecture of visual cognition and briefly describes some work in the areas of routines, attention, surfaces, objects, and events (motion, causality, and agency). Most vision scientists avoid being too explicit when presenting concepts about visual cognition, having learned that explicit models invite easy criticism. What we see in the literature is ample evidence for visual cognition, but few or only cautious attempts to detail how it might work. This is the great unfinished business of vision research: at some point we will be done with characterizing how the visual system measures the world and we will have to return to the question of how vision constructs models of objects, surfaces, scenes, and events. PMID:21329719

  2. Laser printing of cells into 3D scaffolds

    International Nuclear Information System (INIS)

    Ovsianikov, A; Gruene, M; Koch, L; Maiorana, F; Chichkov, B; Pflaum, M; Wilhelmi, M; Haverich, A

    2010-01-01

    One of the most promising approaches in tissue engineering is the application of 3D scaffolds, which provide cell support and guidance in the initial tissue formation stage. The porosity of the scaffold and internal pore organization influence cell migration and play a major role in its biodegradation dynamics, nutrient diffusion and mechanical stability. In order to control cell migration and cellular interactions within the scaffold, novel technologies capable of producing 3D structures in accordance with predefined design are required. The two-photon polymerization (2PP) technique, used in this report for the fabrication of scaffolds, allows the realization of arbitrary 3D structures with submicron spatial resolution. Highly porous 3D scaffolds, produced by 2PP of acrylated poly(ethylene glycol), are seeded with cells by means of laser-induced forward transfer (LIFT). In this laser printing approach, a propulsive force, resulting from laser-induced shock wave, is used to propel individual cells or cell groups from a donor substrate towards the receiver substrate. We demonstrate that with this technique printing of multiple cell types into 3D scaffolds is possible. Combination of LIFT and 2PP provides a route for the realization of 3D multicellular tissue constructs and artificial ECM engineered on the microscale.

  3. Automated quality characterization of 3D printed bone scaffolds

    Directory of Open Access Journals (Sweden)

    Tzu-Liang Bill Tseng

    2014-07-01

    Full Text Available Optimization of design is an important step in obtaining tissue engineering scaffolds with appropriate shapes and inner microstructures. Different shapes and sizes of scaffolds are modeled using UGS NX 6.0 software with variable pore sizes. The quality issue we are concerned is the scaffold porosity, which is mainly caused by the fabrication inaccuracies. Bone scaffolds are usually characterized using a scanning electron microscope, but this study presents a new automated inspection and classification technique. Due to many numbers and size variations for the pores, the manual inspection of the fabricated scaffolds tends to be error-prone and costly. Manual inspection also raises the chance of contamination. Thus, non-contact, precise inspection is preferred. In this study, the critical dimensions are automatically measured by the vision camera. The measured data are analyzed to classify the quality characteristics. The automated inspection and classification techniques developed in this study are expected to improve the quality of the fabricated scaffolds and reduce the overall cost of manufacturing.

  4. Investigation of cancer cell behavior on nanofibrous scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Szot, Christopher S.; Buchanan, Cara F. [School of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States); Gatenholm, Paul [School of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States); Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Rylander, Marissa Nichole [School of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States); Freeman, Joseph W., E-mail: jwfreeman@vt.edu [School of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States)

    2011-01-01

    Tissue engineering and the use of nanofibrous biomaterial scaffolds offer a unique perspective for studying cancer development in vitro. Current in vitro models of tumorigenesis are limited by the use of static, two-dimensional (2D) cell culture monolayers that lack the structural architecture necessary for cell-cell interaction and three-dimensional (3D) scaffolds that are too simplistic for studying basic pathological mechanisms. In this study, two nanofibrous biomaterials that mimic the structure of the extracellular matrix, bacterial cellulose and electrospun polycaprolactone (PCL)/collagen I, were investigated as potential 3D scaffolds for an in vitro cancer model. Multiple cancer cell lines were cultured on each scaffold material and monitored for cell viability, proliferation, adhesion, infiltration, and morphology. Both bacterial cellulose and electrospun PCL/collagen I, which have nano-scale structures on the order of 100-500 nm, have been used in many diverse tissue engineering applications. Cancer cell adhesion and growth were limited on bacterial cellulose, while all cellular processes were enhanced on the electrospun scaffolds. This initial analysis has demonstrated the potential of electrospun PCL/collagen I scaffolds toward the development of an improved 3D in vitro cancer model.

  5. Scaffolding as an effort for thinking process optimization on heredity

    Science.gov (United States)

    Azizah, N. R.; Masykuri, M.; Prayitno, B. A.

    2018-04-01

    Thinking is an activity and process of manipulating and transforming data or information into memory. Thinking process is different between one and other person. Thinking process can be developed by interaction between student and their environment, such as scaffolding. Given scaffolding is based on each student necessity. There are 2 level on scaffolding such as explaining, reviewing, and restructuring; and developing conceptual thinking. This research is aimed to describe student’s thinking process on heredity especially on inheritance that is before and after scaffolding. This research used descriptive qualitative method. There were three kinds of subject degree such as the students with high, middle, and low achieving students. The result showed that subjects had some difficulty in dihybrid inheritance question in different place. Most difficulty was on determining the number of different characteristic, parental genotype, gamete, and ratio of genotype and phenotype F2. Based on discussed during scaffolding showed that the subjects have some misunderstanding terms and difficulty to determine parental, gamete, genotype, and phenotype. Final result in this research showed that the subjects develop thinking process higher after scaffolding. Therefore the subjects can solve question properly.

  6. Chitosan/bioactive glass nanoparticles scaffolds with shape memory properties.

    Science.gov (United States)

    Correia, Cristina O; Leite, Álvaro J; Mano, João F

    2015-06-05

    We propose a combination of chitosan (CHT) with bioactive glass nanoparticles (BG-NPs) in order to produce CHT/BG-NPs scaffolds that combine the shape memory properties of chitosan and the biomineralization ability of BG-NPs for applications in bone regeneration. The addition of BG-NPs prepared by a sol-gel route to the CHT polymeric matrix improved the bioactivity of the nanocomposite scaffold, as seen by the precipitation of bone-like apatite layer upon immersion in simulated body fluid (SBF). Shape memory tests were carried out while the samples were immersed in varying compositions of water/ethanol mixtures. Dehydration with ethanol enables to fix a temporary shape of a deformed scaffold that recovers the initial geometry upon water uptake. The scaffolds present good shape memory properties characterized by a recovery ratio of 87.5% for CHT and 89.9% for CHT/BG-NPs and a fixity ratio of 97.2% for CHT and 98.2% for CHT/BG-NPs (for 30% compressive deformation). The applicability of such structures was demonstrated by a good geometrical accommodation of a previously compressed scaffold in a bone defect. The results indicate that the developed CHT/BG-NPs nanocomposite scaffolds have potential for being applied in bone tissue engineering. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Mechanoactive scaffold induces tendon remodeling and expression of fibrocartilage markers.

    Science.gov (United States)

    Spalazzi, Jeffrey P; Vyner, Moira C; Jacobs, Matthew T; Moffat, Kristen L; Lu, Helen H

    2008-08-01

    Biological fixation of soft tissue-based grafts for anterior cruciate ligament (ACL) reconstruction poses a major clinical challenge. The ACL integrates with subchondral bone through a fibrocartilage enthesis, which serves to minimize stress concentrations and enables load transfer between two distinct tissue types. Functional integration thus requires the reestablishment of this fibrocartilage interface on reconstructed ACL grafts. We designed and characterized a novel mechanoactive scaffold based on a composite of poly-alpha-hydroxyester nanofibers and sintered microspheres; we then used the scaffold to test the hypothesis that scaffold-induced compression of tendon grafts would result in matrix remodeling and the expression of fibrocartilage interface-related markers. Histology coupled with confocal microscopy and biochemical assays were used to evaluate the effects of scaffold-induced compression on tendon matrix collagen distribution, cellularity, proteoglycan content, and gene expression over a 2-week period. Scaffold contraction resulted in over 15% compression of the patellar tendon graft and upregulated the expression of fibrocartilage-related markers such as Type II collagen, aggrecan, and transforming growth factor-beta3 (TGF-beta3). Additionally, proteoglycan content was higher in the compressed tendon group after 1 day. The data suggest the potential of a mechanoactive scaffold to promote the formation of an anatomic fibrocartilage enthesis on tendon-based ACL reconstruction grafts.

  8. Scaffold filling, contig fusion and comparative gene order inference

    Directory of Open Access Journals (Sweden)

    Rounsley Steve

    2010-06-01

    Full Text Available Abstract Background There has been a trend in increasing the phylogenetic scope of genome sequencing without finishing the sequence of the genome. Increasing numbers of genomes are being published in scaffold or contig form. Rearrangement algorithms, however, including gene order-based phylogenetic tools, require whole genome data on gene order or syntenic block order. How then can we use rearrangement algorithms to compare genomes available in scaffold form only? Can the comparative evidence predict the location of unsequenced genes? Results Our method involves optimally filling in genes missing from the scaffolds, while incorporating the augmented scaffolds directly into the rearrangement algorithms as if they were chromosomes. This is accomplished by an exact, polynomial-time algorithm. We then correct for the number of extra fusion/fission operations required to make scaffolds comparable to full assemblies. We model the relationship between the ratio of missing genes actually absent from the genome versus merely unsequenced ones, on one hand, and the increase of genomic distance after scaffold filling, on the other. We estimate the parameters of this model through simulations and by comparing the angiosperm genomes Ricinus communis and Vitis vinifera. Conclusions The algorithm solves the comparison of genomes with 18,300 genes, including 4500 missing from one genome, in less than a minute on a MacBook, putting virtually all genomes within range of the method.

  9. Scaffold filling, contig fusion and comparative gene order inference.

    Science.gov (United States)

    Muñoz, Adriana; Zheng, Chunfang; Zhu, Qian; Albert, Victor A; Rounsley, Steve; Sankoff, David

    2010-06-04

    There has been a trend in increasing the phylogenetic scope of genome sequencing without finishing the sequence of the genome. Increasing numbers of genomes are being published in scaffold or contig form. Rearrangement algorithms, however, including gene order-based phylogenetic tools, require whole genome data on gene order or syntenic block order. How then can we use rearrangement algorithms to compare genomes available in scaffold form only? Can the comparative evidence predict the location of unsequenced genes? Our method involves optimally filling in genes missing from the scaffolds, while incorporating the augmented scaffolds directly into the rearrangement algorithms as if they were chromosomes. This is accomplished by an exact, polynomial-time algorithm. We then correct for the number of extra fusion/fission operations required to make scaffolds comparable to full assemblies. We model the relationship between the ratio of missing genes actually absent from the genome versus merely unsequenced ones, on one hand, and the increase of genomic distance after scaffold filling, on the other. We estimate the parameters of this model through simulations and by comparing the angiosperm genomes Ricinus communis and Vitis vinifera. The algorithm solves the comparison of genomes with 18,300 genes, including 4500 missing from one genome, in less than a minute on a MacBook, putting virtually all genomes within range of the method.

  10. Cognitive linguistics.

    Science.gov (United States)

    Evans, Vyvyan

    2012-03-01

    Cognitive linguistics is one of the fastest growing and influential perspectives on the nature of language, the mind, and their relationship with sociophysical (embodied) experience. It is a broad theoretical and methodological enterprise, rather than a single, closely articulated theory. Its primary commitments are outlined. These are the Cognitive Commitment-a commitment to providing a characterization of language that accords with what is known about the mind and brain from other disciplines-and the Generalization Commitment-which represents a dedication to characterizing general principles that apply to all aspects of human language. The article also outlines the assumptions and worldview which arises from these commitments, as represented in the work of leading cognitive linguists. WIREs Cogn Sci 2012, 3:129-141. doi: 10.1002/wcs.1163 For further resources related to this article, please visit the WIREs website. Copyright © 2012 John Wiley & Sons, Inc.

  11. Entrepreneurial Cognition

    DEFF Research Database (Denmark)

    Zichella, Giulio

    entrepreneurs and nonentrepreneurs differ in their behavioral susceptibility to prior outcomes, increasing degrees of risk, risk perception, and predictive information. The empirical analyses are based on data from a laboratory experiment that I designed and conducted in October 2014. Individuals participating......Research in decision making and cognition has a long tradition in economics and management and represents a substantial stream of research in entrepreneurship. Risk and uncertainty are two characteristics of the decision environment. It has long been believed that entrepreneurs who need to make...... business judgments in such environments are less risk- and uncertainty-averse than non-entrepreneurs. However, this theoretical prediction has not been supported by empirical evidence. Instead, entrepreneurs have been found to be more susceptible to cognitive biases and heuristics. These cognitive...

  12. Embodied Language Learning and Cognitive Bootstrapping

    DEFF Research Database (Denmark)

    Lyon, C.E.; Nehaniv, C. L.; Saunders, Joe

    2016-01-01

    Co-development of action, conceptualization and social interaction mutually scaffold and support each other within a virtuous feedback cycle in the development of human language in children. Within this framework, the purpose of this article is to bring together diverse but complementary accounts...... of research methods that jointly contribute to our understanding of cognitive development and in particular, language acquisition in robots. Thus, we include research pertaining to developmental robotics, cognitive science, psychology, linguistics and neuroscience, as well as practical computer science...... the humanoid robot iCub are reported, while human learning relevant to developmental robotics has also contributed useful results. Disparate approaches are brought together via common underlying design principles. Without claiming to model human language acquisition directly, we are nonetheless inspired...

  13. Cognitive apprenticeship in health sciences education: a qualitative review.

    Science.gov (United States)

    Lyons, Kayley; McLaughlin, Jacqueline E; Khanova, Julia; Roth, Mary T

    2017-08-01

    Cognitive apprenticeship theory emphasizes the process of making expert thinking "visible" to students and fostering the cognitive and meta-cognitive processes required for expertise. The purpose of this review was to evaluate the use of cognitive apprenticeship theory with the primary aim of understanding how and to what extent the theory has been applied to the design, implementation, and analysis of education in the health sciences. The initial search yielded 149 articles, with 45 excluded because they contained the term "cognitive apprenticeship" only in reference list. The remaining 104 articles were categorized using a theory talk coding scheme. An in depth qualitative synthesis and review was conducted for the 26 articles falling into the major theory talk category. Application of cognitive apprenticeship theory tended to focus on the methods dimension (e.g., coaching, mentoring, scaffolding), with some consideration for the content and sociology dimensions. Cognitive apprenticeship was applied in various disciplines (e.g., nursing, medicine, veterinary) and educational settings (e.g., clinical, simulations, online). Health sciences education researchers often used cognitive apprenticeship to inform instructional design and instrument development. Major recommendations from the literature included consideration for contextual influences, providing faculty development, and expanding application of the theory to improve instructional design and student outcomes. This body of research provides critical insight into cognitive apprenticeship theory and extends our understanding of how to develop expert thinking in health sciences students. New research directions should apply the theory into additional aspects of health sciences educational research, such as classroom learning and interprofessional education.

  14. Fabrication of chitin-chitosan/nano TiO2-composite scaffolds for tissue engineering applications.

    Science.gov (United States)

    Jayakumar, R; Ramachandran, Roshni; Divyarani, V V; Chennazhi, K P; Tamura, H; Nair, S V

    2011-03-01

    In this study, we prepared chitin-chitosan/nano TiO(2) composite scaffolds using lyophilization technique for bone tissue engineering. The prepared composite scaffold was characterized using SEM, XRD, FTIR and TGA. In addition, swelling, degradation and biomineralization capability of the composite scaffolds were evaluated. The developed composite scaffold showed controlled swelling and degradation when compared to the control scaffold. Cytocompatibility of the scaffold was assessed by MTT assay and cell attachment studies using osteoblast-like cells (MG-63), fibroblast cells (L929) and human mesenchymal stem cells (hMSCs). Results indicated no sign of toxicity and cells were found attached to the pore walls within the scaffolds. These results suggested that the developed composite scaffold possess the prerequisites for tissue engineering scaffolds and it can be used for tissue engineering applications. Copyright © 2010 Elsevier B.V. All rights reserved.

  15. Porous poly (lactic-co-glycolide) microsphere sintered scaffolds for tissue repair applications

    International Nuclear Information System (INIS)

    Wang Yingjun; Shi Xuetao; Ren Li; Wang Chunming; Wang Dongan

    2009-01-01

    In this paper, a new route to preparing porous poly (lactic-co-glycolide) (PLGA) scaffolds for bone tissue repair applications was developed. Novel porous PLGA scaffolds were fabricated via microsphere sintered technique and gas forming technique. Ammonium bicarbonate was used to regulate porosity of these porous scaffolds. Porosity of the scaffolds, and cell attachment, viability and proliferation on the scaffolds were evaluated. The results indicated that PLGA porous scaffolds were with the porosity from around 30% to 95% by regulating ammonium bicarbonate content from 0 to 10%. We also found that PLGA porous microsphere scaffolds benefited cell attachment and viability. Taken together, the achieved porous scaffolds have controlled porosity and also support mesenchymal stem cell proliferation, which could serve as potential scaffolds for bone repair applications.

  16. Magnesium Oxide Nanoparticles Reinforced Electrospun Alginate-Based Nanofibrous Scaffolds with Improved Physical Properties

    Directory of Open Access Journals (Sweden)

    R. T. De Silva

    2017-01-01

    Full Text Available Mechanically robust alginate-based nanofibrous scaffolds were successfully fabricated by electrospinning method to mimic the natural extracellular matrix structure which benefits development and regeneration of tissues. Alginate-based nanofibres were electrospun from an alginate/poly(vinyl alcohol (PVA polyelectrolyte complex. SEM images revealed the spinnability of the complex composite nanofibrous scaffolds, showing randomly oriented, ultrafine, and virtually defects-free alginate-based/MgO nanofibrous scaffolds. Here, it is shown that an alginate/PVA complex scaffold, blended with near-spherical MgO nanoparticles (⌀ 45 nm at a predetermined concentration (10% (w/w, is electrospinnable to produce a complex composite nanofibrous scaffold with enhanced mechanical stability. For the comparison purpose, chemically cross-linked electrospun alginate-based scaffolds were also fabricated. Tensile test to rupture revealed the significant differences in the tensile strength and elastic modulus among the alginate scaffolds, alginate/MgO scaffolds, and cross-linked alginate scaffolds (P<0.05. In contrast to cross-linked alginate scaffolds, alginate/MgO scaffolds yielded the highest tensile strength and elastic modulus while preserving the interfibre porosity of the scaffolds. According to the thermogravimetric analysis, MgO reinforced alginate nanofibrous scaffolds exhibited improved thermal stability. These novel alginate-based/MgO scaffolds are economical and versatile and may be further optimised for use as extracellular matrix substitutes for repair and regeneration of tissues.

  17. [Three-dimensional parallel collagen scaffold promotes tendon extracellular matrix formation].

    Science.gov (United States)

    Zheng, Zefeng; Shen, Weiliang; Le, Huihui; Dai, Xuesong; Ouyang, Hongwei; Chen, Weishan

    2016-03-01

    To investigate the effects of three-dimensional parallel collagen scaffold on the cell shape, arrangement and extracellular matrix formation of tendon stem cells. Parallel collagen scaffold was fabricated by unidirectional freezing technique, while random collagen scaffold was fabricated by freeze-drying technique. The effects of two scaffolds on cell shape and extracellular matrix formation were investigated in vitro by seeding tendon stem/progenitor cells and in vivo by ectopic implantation. Parallel and random collagen scaffolds were produced successfully. Parallel collagen scaffold was more akin to tendon than random collagen scaffold. Tendon stem/progenitor cells were spindle-shaped and unified orientated in parallel collagen scaffold, while cells on random collagen scaffold had disorder orientation. Two weeks after ectopic implantation, cells had nearly the same orientation with the collagen substance. In parallel collagen scaffold, cells had parallel arrangement, and more spindly cells were observed. By contrast, cells in random collagen scaffold were disorder. Parallel collagen scaffold can induce cells to be in spindly and parallel arrangement, and promote parallel extracellular matrix formation; while random collagen scaffold can induce cells in random arrangement. The results indicate that parallel collagen scaffold is an ideal structure to promote tendon repairing.

  18. Development of hybrid scaffolds using ceramic and hydrogel for articular cartilage tissue regeneration.

    Science.gov (United States)

    Seol, Young-Joon; Park, Ju Young; Jeong, Wonju; Kim, Tae-Ho; Kim, Shin-Yoon; Cho, Dong-Woo

    2015-04-01

    The regeneration of articular cartilage consisting of hyaline cartilage and hydrogel scaffolds has been generally used in tissue engineering. However, success in in vivo studies has been rarely reported. The hydrogel scaffolds implanted into articular cartilage defects are mechanically unstable and it is difficult for them to integrate with the surrounding native cartilage tissue. Therefore, it is needed to regenerate cartilage and bone tissue simultaneously. We developed hybrid scaffolds with hydrogel scaffolds for cartilage tissue and with ceramic scaffolds for bone tissue. For in vivo study, hybrid scaffolds were press-fitted into osteochondral tissue defects in a rabbit knee joints and the cartilage tissue regeneration in blank, hydrogel scaffolds, and hybrid scaffolds was compared. In 12th week after implantation, the histological and immunohistochemical analyses were conducted to evaluate the cartilage tissue regeneration. In the blank and hydrogel scaffold groups, the defects were filled with fibrous tissues and the implanted hydrogel scaffolds could not maintain their initial position; in the hybrid scaffold group, newly generated cartilage tissues were morphologically similar to native cartilage tissues and were smoothly connected to the surrounding native tissues. This study demonstrates hybrid scaffolds containing hydrogel and ceramic scaffolds can provide mechanical stability to hydrogel scaffolds and enhance cartilage tissue regeneration at the defect site. © 2014 Wiley Periodicals, Inc.

  19. Fabrication of chitosan/gallic acid 3D microporous scaffold for tissue engineering applications.

    Science.gov (United States)

    Thangavel, Ponrasu; Ramachandran, Balaji; Muthuvijayan, Vignesh

    2016-05-01

    This study explores the potential of gallic acid incorporated chitosan (CS/GA) 3D scaffolds for tissue engineering applications. Scaffolds were prepared by freezing and lyophilization technique and characterized. FTIR spectra confirmed the presence of GA in chitosan (CS) gel. DSC and TGA analysis revealed that the structure of chitosan was not altered due to the incorporation of GA, but thermal stability was significantly increased compared to the CS scaffold. SEM micrographs showed smooth, homogeneous, and microporous architecture of the scaffolds with good interconnectivity. CS/GA scaffolds exhibited approximately 90% porosity on average, increased swelling (600-900%) and controlled biodegradation (15-40%) in PBS (pH 7.4 at 37°C) with 1 mg/mL of lysozyme. CS/GA scaffolds showed 2-4 fold decrease in CFUs (p < 0.05) for both gram positive and gram negative bacteria compared to the CS scaffold. Cytotoxicity of these scaffolds was evaluated using NIH 3T3 L1 fibroblast cells. CS/GA 0.25% scaffold showed similar viability with CS scaffold at 24 and 48 h. CS/GA scaffolds (0.5-1.0%) showed 60-75% viability at 24 h and 90% at 48 h. SEM images showed that an increased cell attachment was observed for CS/GA scaffolds compared to CS scaffolds. These findings authenticate that CS/GA scaffolds were cytocompatible and would be useful for tissue engineering applications. © 2015 Wiley Periodicals, Inc.

  20. Scaffolded instruction: promoting biliteracy for second language learners with language/learning disabilities

    Directory of Open Access Journals (Sweden)

    Lorri M. Johnson-Perrodin

    1998-04-01

    Full Text Available For culturally and linguistically diverse learners, scaffolded instruction is important for not only content learning but for second language learning. In this case study of two bilingual education teachers and their third grade students, we expand the traditional concept of scaffolded instruction (e.g., experts, tools, routines to include Krashen's notion of comprehensible input (1982 as a scaffold for acquiring a second language yielding an effective transfer of first language (L1 academic language development to second language (L2 academic language development. A variety of scaffolds were used as multiple support systems that facilitated the biliteracy learning process for the students. Peer interactions, expert/ novice groupings, and literacy tools and routines were some of the scaffolds used to facilitate biliteracy instruction. Key to transfer from L1 to L2 was the teaching the tools and routines in the students' L1 prior to biliteracy instruction. Considerations for students with language/learning disabilities (LLD were included in this case study. Results suggest that by scaffolding for L2 development using previously acquired knowledge from first language (L1 instruction, students including those with LLD efficiently transferred cognitive academic skills from L1 to L2. Educational implications are discussed. Para alumnos cultural y linguisticamente diversos, la instrucción basada en el andamiaje es importante no unicamente para el contenido del aprendizaje sino para el aprendizaje de un segundo idioma. En este estudio de caso de dos profesores bilingües y sus alumnos de tercer curso, ampliamos el tradicional concepto de instrucción mediante andamiaje (e.g.,expertos, herramientas, rutinas incluyendo la noción de Krashen de entrada comprensiba (1982 como un apoyo para adquirir un segundo lenguaje produciendo un transfer efectivo del primer idioma desarrollado academicamente (L1 al segundo (L2. Una gran variedad de andamiajes fueron

  1. Gelatin–PMVE/MA composite scaffold promotes expansion of embryonic stem cells

    International Nuclear Information System (INIS)

    Chhabra, Hemlata; Gupta, Priyanka; Verma, Paul J.; Jadhav, Sameer; Bellare, Jayesh R.

    2014-01-01

    We introduce a new composite scaffold of gelatin and polymethyl vinyl ether-alt-maleic anhydride (PMVE/MA) for expansion of embryonic stem cells (ESCs) in an in vitro environment. To optimize the scaffold, we prepared a gelatin scaffold (G) and three composite scaffolds namely GP-1, GP-2, and GP-3 with varying PMVE/MA concentrations (0.2–1%) and characterized them by scanning electron microscopy (SEM), swelling study, compression testing and FTIR. SEM micrographs revealed interconnected porous structure in all the scaffolds. The permissible hemolysis ratio and activation of platelets by scaffolds confirmed the hemocompatibility of scaffolds. Initial biocompatibility assessment of scaffolds was conducted using hepatocarcinoma (Hep G2) cells and adhesion, proliferation and infiltration of Hep G2 cells in depth of scaffolds were observed, proving the scaffold's biocompatibility. Further Oct4B2 mouse embryonic stem cells (mESCs), which harbor a green fluorescence protein transgene under regulatory control of the Oct4 promotor, were examined for expansion on scaffolds with MTT assay. The GP-2 scaffold demonstrated the best cell proliferation and was further explored for ESC adherence and infiltration in depth (SEM and confocal), and pluripotent state of mESCs was assessed with the expression of Oct4-GFP and stage-specific embryonic antigen-1 (SSEA-1). This study reports the first demonstration of biocompatibility of gelatin–PMVE/MA composite scaffold and presents this scaffold as a promising candidate for embryonic stem cell based tissue engineering. - Highlights: • Composite scaffolds of gelatin and PMVE/MA were prepared by freeze-drying method. • SEM micrographs showed porous structure in all scaffolds of varying pore dimension. • GP-2 composite exhibited better cellular response in comparison to other scaffolds. • mESCs proliferated and expressed Oct-4 and SSEA-1, when cultured on GP-2 scaffold

  2. The response of tenocytes to commercial scaffolds used for rotator cuff repair

    Directory of Open Access Journals (Sweden)

    RDJ Smith

    2017-01-01

    Full Text Available Surgical repairs of rotator cuff tears have high re-tear rates and many scaffolds have been developed to augment the repair. Understanding the interaction between patients’ cells and scaffolds is important for improving scaffold performance and tendon healing. In this in vitro study, we investigated the response of patient-derived tenocytes to eight different scaffolds. Tested scaffolds included X-Repair, Poly-Tape, LARS Ligament, BioFiber (synthetic scaffolds, BioFiber-CM (biosynthetic scaffold, GraftJacket, Permacol, and Conexa (biological scaffolds. Cell attachment, proliferation, gene expression, and morphology were assessed. After one day, more cells attached to synthetic scaffolds with dense, fine and aligned fibres (X-Repair and Poly-Tape. Despite low initial cell attachment, the human dermal scaffold (GraftJacket promoted the greatest proliferation of cells over 13 days. Expression of collagen types I and III were upregulated in cells grown on non-cross-linked porcine dermis (Conexa. Interestingly, the ratio of collagen I to collagen III mRNA was lower on all dermal scaffolds compared to synthetic and biosynthetic scaffolds. These findings demonstrate significant differences in the response of patient-derived tendon cells to scaffolds that are routinely used for rotator cuff surgery. Synthetic scaffolds promoted increased cell adhesion and a tendon-like cellular phenotype, while biological scaffolds promoted cell proliferation and expression of collagen genes. However, no single scaffold was superior. Our results may help understand the way that patients’ cells interact with scaffolds and guide the development of new scaffolds in the future.

  3. Gelatin–PMVE/MA composite scaffold promotes expansion of embryonic stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Chhabra, Hemlata [Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai (India); Gupta, Priyanka [Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai (India); IITB-Monash Research Academy, Mumbai (India); Department of Chemical Engineering, Monash University, Melbourne (Australia); Verma, Paul J. [Turretfield Research Centre, South Australian Research and Development Institute, Rosedale, South Australia (Australia); Jadhav, Sameer; Bellare, Jayesh R. [Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai (India)

    2014-04-01

    We introduce a new composite scaffold of gelatin and polymethyl vinyl ether-alt-maleic anhydride (PMVE/MA) for expansion of embryonic stem cells (ESCs) in an in vitro environment. To optimize the scaffold, we prepared a gelatin scaffold (G) and three composite scaffolds namely GP-1, GP-2, and GP-3 with varying PMVE/MA concentrations (0.2–1%) and characterized them by scanning electron microscopy (SEM), swelling study, compression testing and FTIR. SEM micrographs revealed interconnected porous structure in all the scaffolds. The permissible hemolysis ratio and activation of platelets by scaffolds confirmed the hemocompatibility of scaffolds. Initial biocompatibility assessment of scaffolds was conducted using hepatocarcinoma (Hep G2) cells and adhesion, proliferation and infiltration of Hep G2 cells in depth of scaffolds were observed, proving the scaffold's biocompatibility. Further Oct4B2 mouse embryonic stem cells (mESCs), which harbor a green fluorescence protein transgene under regulatory control of the Oct4 promotor, were examined for expansion on scaffolds with MTT assay. The GP-2 scaffold demonstrated the best cell proliferation and was further explored for ESC adherence and infiltration in depth (SEM and confocal), and pluripotent state of mESCs was assessed with the expression of Oct4-GFP and stage-specific embryonic antigen-1 (SSEA-1). This study reports the first demonstration of biocompatibility of gelatin–PMVE/MA composite scaffold and presents this scaffold as a promising candidate for embryonic stem cell based tissue engineering. - Highlights: • Composite scaffolds of gelatin and PMVE/MA were prepared by freeze-drying method. • SEM micrographs showed porous structure in all scaffolds of varying pore dimension. • GP-2 composite exhibited better cellular response in comparison to other scaffolds. • mESCs proliferated and expressed Oct-4 and SSEA-1, when cultured on GP-2 scaffold.

  4. Dark matter maps reveal cosmic scaffolding

    Energy Technology Data Exchange (ETDEWEB)

    Massey, R; Rhodes, J; Ellis, R; Scoville, N; Capak, P [CALTECH, Pasadena, CA 91125 (United States); Rhodes, J [CALTECH, Jet Prop Lab, Pasadena, CA 91109 (United States); Leauthaud, A; Kneib, J P [Lab Astrophys Marseille, F-13376 Marseille, (France); Finoguenov, A [Max Planck Inst Extraterr Phys, D-85748 Garching, (Germany); Bacon, D; Taylor, A [Inst Astron, Edinburgh EH9 3HJ, Midlothian, (United Kingdom); Aussel, H; Refregier, A [CNRS, CEA, Unite Mixte Rech, AIM, F-91191 Gif Sur Yvette, (France); Koekemoer, A; Mobasher, B [Univ Paris 07, CE Saclay, UMR 7158, F-91191 Gif Sur Yvette, (France); McCracken, H [Space Telescope Sci Inst, Baltimore, MD 21218 (United States); Pires, S; Starck, J L [Univ Paris 06, Inst Astrophys Paris, F-75014 Paris, (France); Pires, S [Ctr Etud Saclay, CEA, DSM, DAPNIA, SEDI, F-91191 Gif Sur Yvette, (France); Sasaki, S; Taniguchi, Y [Ehime Univ, Dept Phys, Matsuyama, Ehime 7908577, (Japan); Taylor, J [Univ Waterloo, Dept Phys and Astron, Waterloo, ON N2L 3G1, (Canada)

    2007-07-01

    Ordinary baryonic particles (such as protons and neutrons) account for only one-sixth of the total matter in the Universe. The remainder is a mysterious 'dark matter' component, which does not interact via electromagnetism and thus neither emits nor reflects light. As dark matter cannot be seen directly using traditional observations, very little is currently known about its properties. It does interact via gravity, and is most effectively probed through gravitational lensing: the deflection of light from distant galaxies by the gravitational attraction of foreground mass concentrations. This is a purely geometrical effect that is free of astrophysical assumptions and sensitive to all matter - whether baryonic or dark. Here we show high-fidelity maps of the large-scale distribution of dark matter, resolved in both angle and depth. We find a loose network of filaments, growing over time, which intersect in massive structures at the locations of clusters of galaxies. Our results are consistent with predictions of gravitationally induced structure formation, in which the initial, smooth distribution of dark matter collapses into filaments then into clusters, forming a gravitational scaffold into which gas can accumulate, and stars can be built. (authors)

  5. Dark matter maps reveal cosmic scaffolding

    International Nuclear Information System (INIS)

    Massey, R.; Rhodes, J.; Ellis, R.; Scoville, N.; Capak, P.; Rhodes, J.; Leauthaud, A.; Kneib, J.P.; Finoguenov, A.; Bacon, D.; Taylor, A.; Aussel, H.; Refregier, A.; Koekemoer, A.; Mobasher, B.; McCracken, H.; Pires, S.; Starck, J.L.; Pires, S.; Sasaki, S.; Taniguchi, Y.; Taylor, J.

    2007-01-01

    Ordinary baryonic particles (such as protons and neutrons) account for only one-sixth of the total matter in the Universe. The remainder is a mysterious 'dark matter' component, which does not interact via electromagnetism and thus neither emits nor reflects light. As dark matter cannot be seen directly using traditional observations, very little is currently known about its properties. It does interact via gravity, and is most effectively probed through gravitational lensing: the deflection of light from distant galaxies by the gravitational attraction of foreground mass concentrations. This is a purely geometrical effect that is free of astrophysical assumptions and sensitive to all matter - whether baryonic or dark. Here we show high-fidelity maps of the large-scale distribution of dark matter, resolved in both angle and depth. We find a loose network of filaments, growing over time, which intersect in massive structures at the locations of clusters of galaxies. Our results are consistent with predictions of gravitationally induced structure formation, in which the initial, smooth distribution of dark matter collapses into filaments then into clusters, forming a gravitational scaffold into which gas can accumulate, and stars can be built. (authors)

  6. Dark matter maps reveal cosmic scaffolding.

    Science.gov (United States)

    Massey, Richard; Rhodes, Jason; Ellis, Richard; Scoville, Nick; Leauthaud, Alexie; Finoguenov, Alexis; Capak, Peter; Bacon, David; Aussel, Hervé; Kneib, Jean-Paul; Koekemoer, Anton; McCracken, Henry; Mobasher, Bahram; Pires, Sandrine; Refregier, Alexandre; Sasaki, Shunji; Starck, Jean-Luc; Taniguchi, Yoshi; Taylor, Andy; Taylor, James

    2007-01-18

    Ordinary baryonic particles (such as protons and neutrons) account for only one-sixth of the total matter in the Universe. The remainder is a mysterious 'dark matter' component, which does not interact via electromagnetism and thus neither emits nor reflects light. As dark matter cannot be seen directly using traditional observations, very little is currently known about its properties. It does interact via gravity, and is most effectively probed through gravitational lensing: the deflection of light from distant galaxies by the gravitational attraction of foreground mass concentrations. This is a purely geometrical effect that is free of astrophysical assumptions and sensitive to all matter--whether baryonic or dark. Here we show high-fidelity maps of the large-scale distribution of dark matter, resolved in both angle and depth. We find a loose network of filaments, growing over time, which intersect in massive structures at the locations of clusters of galaxies. Our results are consistent with predictions of gravitationally induced structure formation, in which the initial, smooth distribution of dark matter collapses into filaments then into clusters, forming a gravitational scaffold into which gas can accumulate, and stars can be built.

  7. Calcium phosphate cement scaffolds with PLGA fibers.

    Science.gov (United States)

    Vasconcellos, Letícia Araújo; dos Santos, Luís Alberto

    2013-04-01

    The use of calcium phosphate-based biomaterials has revolutionized current orthopedics and dentistry in repairing damaged parts of the skeletal system. Among those biomaterials, the cement made of hydraulic grip calcium phosphate has attracted great interest due to its biocompatibility and hardening "in situ". However, these cements have low mechanical strength compared with the bones of the human body. In the present work, we have studied the attainment of calcium phosphate cement powders and their addition to poly (co-glycolide) (PLGA) fibers to increase mechanical properties of those cements. We have used a new method that obtains fibers by dripping different reagents. PLGA fibers were frozen after lyophilized. With this new method, which was patented, it was possible to obtain fibers and reinforcing matrix which furthered the increase of mechanical properties, thus allowing the attainment of more resistant materials. The obtained materials were used in the construction of composites and scaffolds for tissue growth, keeping a higher mechanical integrity. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Scaffolding conceptual change in early childhood

    Science.gov (United States)

    Fleer, Marilyn

    1990-01-01

    The general educational literature draws our attention to the limitations of Piaget’s work and presents a number of interesting ideas that science educators and researchers could consider. Of interest are Soviet psychologist Lev Vygotsky’s writings on the zone of proximal development and the more recent writings of Jerome Bruner on scaffolding. The notion of learning as a a socially constructed process in opposition to the more individualistic orientation of Piaget has challenged much of our educational practice. This paper will briefly explore the basic tenets of constructivism and contrast the theories developed from within this paradigm to the work of Vygotsky and Bruner through an analysis of classroom discourse collected from a number of early childhood classes involved in the interactive teaching approach to science. Transcripts of teacher-child discourse are presented as evidence to support the proposition that when the teacher’s role is not clearly defined, the range of teacher-child interactions will vary enormously, and the subsequent learning outcomes for children will be quite different.

  9. Cognitive Variability

    Science.gov (United States)

    Siegler, Robert S.

    2007-01-01

    Children's thinking is highly variable at every level of analysis, from neural and associative levels to the level of strategies, theories, and other aspects of high-level cognition. This variability exists within people as well as between them; individual children often rely on different strategies or representations on closely related problems…

  10. Cognitive Fingerprints

    Science.gov (United States)

    2015-03-25

    is another cognitive fingerprint that has been used extensively for authorship . This work has been ex- tended to authentication by relating keyboard...this work is the inference of high-level features such as personality, gender , and dominant hand but those features have not been integrated to date

  11. Cognitive Science.

    Science.gov (United States)

    Cocking, Rodney R.; Mestre, Jose P.

    The focus of this paper is on cognitive science as a model for understanding the application of human skills toward effective problem-solving. Sections include: (1) "Introduction" (discussing information processing framework, expert-novice distinctions, schema theory, and learning process); (2) "Application: The Expert-Novice…

  12. Novel Textile Scaffolds Generated by Flock Technology for Tissue Engineering of Bone and Cartilage.

    Science.gov (United States)

    Walther, Anja; Hoyer, Birgit; Springer, Armin; Mrozik, Birgit; Hanke, Thomas; Cherif, Chokri; Pompe, Wolfgang; Gelinsky, Michael

    2012-03-22

    Textile scaffolds can be found in a variety of application areas in regenerative medicine and tissue engineering. In the present study we used electrostatic flocking-a well-known textile technology-to produce scaffolds for tissue engineering of bone. Flock scaffolds stand out due to their unique structure: parallel arranged fibers that are aligned perpendicularly to a substrate, resulting in mechanically stable structures with a high porosity. In compression tests we demonstrated good mechanical properties of such scaffolds and in cell culture experiments we showed that flock scaffolds allow attachment and proliferation of human mesenchymal stem cells and support their osteogenic differentiation. These matrices represent promising scaffolds for tissue engineering.

  13. Injectable porous nano-hydroxyapatite/chitosan/tripolyphosphate scaffolds with improved compressive strength for bone regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Uswatta, Suren P.; Okeke, Israel U. [Department of Bioengineering, The University of Toledo, Toledo, OH 43614 (United States); Jayasuriya, Ambalangodage C., E-mail: a.jayasuriya@utoledo.edu [Department of Bioengineering, The University of Toledo, Toledo, OH 43614 (United States); Department of Orthopaedic Surgery, The University of Toledo, Toledo, OH 43614 (United States)

    2016-12-01

    In this study we have fabricated porous injectable spherical scaffolds using chitosan biopolymer, sodium tripolyphosphate (TPP) and nano-hydroxyapatite (nHA). TPP was primarily used as an ionic crosslinker to crosslink nHA/chitosan droplets. We hypothesized that incorporating nHA into chitosan could support osteoconduction by emulating the mineralized cortical bone structure, and improve the Ultimate Compressive Strength (UCS) of the scaffolds. We prepared chitosan solutions with 0.5%, 1% and 2% (w/v) nHA concentration and used simple coacervation and lyophilization techniques to obtain spherical scaffolds. Lyophilized spherical scaffolds had a mean diameter of 1.33 mm (n = 25). Further, portion from each group lyophilized scaffolds were soaked and dried to obtain Lyophilized Soaked and Dried (LSD) scaffolds. LSD scaffolds had a mean diameter of 0.93 mm (n = 25) which is promising property for the injectability. Scanning Electron Microscopy images showed porous surface morphology and interconnected pore structures inside the scaffolds. Lyophilized and LSD scaffolds had surface pores < 10 and 2 μm, respectively. 2% nHA/chitosan LSD scaffolds exhibited UCS of 8.59 MPa compared to UCS of 2% nHA/chitosan lyophilized scaffolds at 3.93 MPa. Standardize UCS values were 79.98 MPa and 357 MPa for 2% nHA/chitosan lyophilized and LSD particles respectively. One-way ANOVA results showed a significant increase (p < 0.001) in UCS of 1% and 2% nHA/chitosan lyophilized scaffolds compared to 0% and 0.5% nHA/chitosan lyophilized scaffolds. Moreover, 2% nHA LSD scaffolds had significantly increased (p < 0.005) their mean UCS by 120% compared to 2% nHA lyophilized scaffolds. In a drawback, all scaffolds have lost their mechanical properties by 95% on the 2nd day when fully immersed in phosphate buffered saline. Additionally live and dead cell assay showed no cytotoxicity and excellent osteoblast attachment to both lyophilized and LSD scaffolds at the end of 14th day of in vitro

  14. Injectable porous nano-hydroxyapatite/chitosan/tripolyphosphate scaffolds with improved compressive strength for bone regeneration

    International Nuclear Information System (INIS)

    Uswatta, Suren P.; Okeke, Israel U.; Jayasuriya, Ambalangodage C.

    2016-01-01

    In this study we have fabricated porous injectable spherical scaffolds using chitosan biopolymer, sodium tripolyphosphate (TPP) and nano-hydroxyapatite (nHA). TPP was primarily used as an ionic crosslinker to crosslink nHA/chitosan droplets. We hypothesized that incorporating nHA into chitosan could support osteoconduction by emulating the mineralized cortical bone structure, and improve the Ultimate Compressive Strength (UCS) of the scaffolds. We prepared chitosan solutions with 0.5%, 1% and 2% (w/v) nHA concentration and used simple coacervation and lyophilization techniques to obtain spherical scaffolds. Lyophilized spherical scaffolds had a mean diameter of 1.33 mm (n = 25). Further, portion from each group lyophilized scaffolds were soaked and dried to obtain Lyophilized Soaked and Dried (LSD) scaffolds. LSD scaffolds had a mean diameter of 0.93 mm (n = 25) which is promising property for the injectability. Scanning Electron Microscopy images showed porous surface morphology and interconnected pore structures inside the scaffolds. Lyophilized and LSD scaffolds had surface pores < 10 and 2 μm, respectively. 2% nHA/chitosan LSD scaffolds exhibited UCS of 8.59 MPa compared to UCS of 2% nHA/chitosan lyophilized scaffolds at 3.93 MPa. Standardize UCS values were 79.98 MPa and 357 MPa for 2% nHA/chitosan lyophilized and LSD particles respectively. One-way ANOVA results showed a significant increase (p < 0.001) in UCS of 1% and 2% nHA/chitosan lyophilized scaffolds compared to 0% and 0.5% nHA/chitosan lyophilized scaffolds. Moreover, 2% nHA LSD scaffolds had significantly increased (p < 0.005) their mean UCS by 120% compared to 2% nHA lyophilized scaffolds. In a drawback, all scaffolds have lost their mechanical properties by 95% on the 2nd day when fully immersed in phosphate buffered saline. Additionally live and dead cell assay showed no cytotoxicity and excellent osteoblast attachment to both lyophilized and LSD scaffolds at the end of 14th day of in vitro

  15. Associations between Inadequate Parenting Practices and Behavioral Problems in Children and Adolescents with Attention Deficit Hyperactivity Disorder

    Directory of Open Access Journals (Sweden)

    Maria Cristina Triguero Veloz Teixeira

    2015-01-01

    Full Text Available Children and adolescents with ADHD present behaviors such as impulsiveness, inattention, and difficulties with personal organization that represent an overload for parents. Moreover, it also increases their level of stress and leads them to resort to inadequate educational strategies. The present study verifies associations between inadequate parenting practices and behavioral profiles of children and adolescents with ADHD. The sample was composed of 22 children with ADHD (age range 6–16 years and their mothers. Spearman correlation analyses were made with the scores of Parenting Style Inventory (PSI and Child Behavior Checklist for ages 6–18 (CBCL/6–18. Results indicate statistically significant associations between behavioral problems and the use of punishment practices and negligence. When assessing a child with ADHD, it is important to verify the predominant types of parenting practices that can influence both immediate interventions and the prognosis of the disorder.

  16. An in vitro study of bone cells grown on an electrospun scaffold for bone repair and reconstruction

    CSIR Research Space (South Africa)

    Wepener, I

    2012-10-01

    Full Text Available This presentation focuses on the manufacturing of the electrospun scaffold and the in vitro testing of this scaffold by making use of human cells. This scaffold is a possible candidate for repair and reconstruction of bone tissue....

  17. Graphene oxide scaffold accelerates cellular proliferative response and alveolar bone healing of tooth extraction socket.

    Science.gov (United States)

    Nishida, Erika; Miyaji, Hirofumi; Kato, Akihito; Takita, Hiroko; Iwanaga, Toshihiko; Momose, Takehito; Ogawa, Kosuke; Murakami, Shusuke; Sugaya, Tsutomu; Kawanami, Masamitsu

    2016-01-01

    Graphene oxide (GO) consisting of a carbon monolayer has been widely investigated for tissue engineering platforms because of its unique properties. For this study, we fabricated a GO-applied scaffold and assessed the cellular and tissue behaviors in the scaffold. A preclinical test was conducted to ascertain whether the GO scaffold promoted bone induction in dog tooth extraction sockets. For this study, GO scaffolds were prepared by coating the surface of a collagen sponge scaffold with 0.1 and 1 µg/mL GO dispersion. Scaffolds were characterized using scanning electron microscopy (SEM), physical testing, cell seeding, and rat subcutaneous implant testing. Then a GO scaffold was implanted into a dog tooth extraction socket. Histological observations were made at 2 weeks postsurgery. SEM observations show that GO attached to the surface of collagen scaffold struts. The GO scaffold exhibited an interconnected structure resembling that of control subjects. GO application improved the physical strength, enzyme resistance, and adsorption of calcium and proteins. Cytocompatibility tests showed that GO application significantly increased osteoblastic MC3T3-E1 cell proliferation. In addition, an assessment of rat subcutaneous tissue response revealed that implantation of 1 µg/mL GO scaffold stimulated cellular ingrowth behavior, suggesting that the GO scaffold exhibited good biocompatibility. The tissue ingrowth area and DNA contents of 1 µg/mL GO scaffold were, respectively, approximately 2.5-fold and 1.4-fold greater than those of the control. Particularly, the infiltration of ED2-positive (M2) macrophages and blood vessels were prominent in the GO scaffold. Dog bone-formation tests showed that 1 µg/mL GO scaffold implantation enhanced bone formation. New bone formation following GO scaffold implantation was enhanced fivefold compared to that in control subjects. These results suggest that GO was biocompatible and had high bone-formation capability for the scaffold

  18. Spiral-structured, nanofibrous, 3D scaffolds for bone tissue engineering.

    Science.gov (United States)

    Wang, Junping; Valmikinathan, Chandra M; Liu, Wei; Laurencin, Cato T; Yu, Xiaojun

    2010-05-01

    Polymeric nanofiber matrices have already been widely used in tissue engineering. However, the fabrication of nanofibers into complex three-dimensional (3D) structures is restricted due to current manufacturing techniques. To overcome this limitation, we have incorporated nanofibers onto spiral-structured 3D scaffolds made of poly (epsilon-caprolactone) (PCL). The spiral structure with open geometries, large surface areas, and porosity will be helpful for improving nutrient transport and cell penetration into the scaffolds, which are otherwise limited in conventional tissue-engineered scaffolds for large bone defects repair. To investigate the effect of structure and fiber coating on the performance of the scaffolds, three groups of scaffolds including cylindrical PCL scaffolds, spiral PCL scaffolds (without fiber coating), and spiral-structured fibrous PCL scaffolds (with fiber coating) have been prepared. The morphology, porosity, and mechanical properties of the scaffolds have been characterized. Furthermore, human osteoblast cells are seeded on these scaffolds, and the cell attachment, proliferation, differentiation, and mineralized matrix deposition on the scaffolds are evaluated. The results indicated that the spiral scaffolds possess porosities within the range of human trabecular bone and an appropriate pore structure for cell growth, and significantly lower compressive modulus and strength than cylindrical scaffolds. When compared with the cylindrical scaffolds, the spiral-structured scaffolds demonstrated enhanced cell proliferation, differentiation, and mineralization and allowed better cellular growth and penetration. The incorporation of nanofibers onto spiral scaffolds further enhanced cell attachment, proliferation, and differentiation. These studies suggest that spiral-structured nanofibrous scaffolds may serve as promising alternatives for bone tissue engineering applications. Copyright 2009 Wiley Periodicals, Inc.

  19. Laminated electrospun nHA/PHB-composite scaffolds mimicking bone extracellular matrix for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zhuoyue [Lab of Tissue Engineering, Faculty of Life Science, Northwest University, 229 TaiBai North Road, Xi' an, Shaanxi Province 710069 (China); Provincial Key Laboratory of Biotechnology of Shaanxi, Northwest University, 229 TaiBai North Road, Xi' an, Shaanxi Province 710069 (China); Song, Yue [Lab of Tissue Engineering, Faculty of Life Science, Northwest University, 229 TaiBai North Road, Xi' an, Shaanxi Province 710069 (China); Zhang, Jing [Lab of Tissue Engineering, Faculty of Life Science, Northwest University, 229 TaiBai North Road, Xi' an, Shaanxi Province 710069 (China); Provincial Key Laboratory of Biotechnology of Shaanxi, Northwest University, 229 TaiBai North Road, Xi' an, Shaanxi Province 710069 (China); Key Laboratory of Resource Biology and Modern Biotechnology in Western China, Ministry of Education, Northwest University, 229 TaiBai North Road, Xi' an, Shaanxi Province, 710069 (China); Liu, Wei [Lab of Tissue Engineering, Faculty of Life Science, Northwest University, 229 TaiBai North Road, Xi' an, Shaanxi Province 710069 (China); Cui, Jihong, E-mail: cjh@nwu.edu.cn [Lab of Tissue Engineering, Faculty of Life Science, Northwest University, 229 TaiBai North Road, Xi' an, Shaanxi Province 710069 (China); Provincial Key Laboratory of Biotechnology of Shaanxi, Northwest University, 229 TaiBai North Road, Xi' an, Shaanxi Province 710069 (China); Key Laboratory of Resource Biology and Modern Biotechnology in Western China, Ministry of Education, Northwest University, 229 TaiBai North Road, Xi' an, Shaanxi Province, 710069 (China); and others

    2017-03-01

    Electrospinning is an effective means to generate nano- to micro-scale polymer fibers resembling native extracellular matrix for tissue engineering. However, a major problem of electrospun materials is that limited pore size and porosity may prevent adequate cellular infiltration and tissue ingrowth. In this study, we first prepared thin layers of hydroxyapatite nanoparticle (nHA)/poly-hydroxybutyrate (PHB) via electrospinning. We then laminated the nHA/PHB thin layers to obtain a scaffold for cell seeding and bone tissue engineering. The results demonstrated that the laminated scaffold possessed optimized cell-loading capacity. Bone marrow mesenchymal stem cells (MSCs) exhibited better adherence, proliferation and osteogenic phenotypes on nHA/PHB scaffolds than on PHB scaffolds. Thereafter, we seeded MSCs onto nHA/PHB scaffolds to fabricate bone grafts. Histological observation showed osteoid tissue formation throughout the scaffold, with most of the scaffold absorbed in the specimens 2 months after implantation, and blood vessels ingrowth into the graft could be observed in the graft. We concluded that electrospun and laminated nanoscaled biocomposite scaffolds hold great therapeutic potential for bone regeneration. - Highlights: • We laminated the nHA/PHB layers to obtain a scaffold for bone tissue engineering. • The laminated scaffold performed optimized cell-loading capacity. • MSCs exhibited osteogenic phenotypes on the laminated scaffold. • Osteoid tissue formed throughout the laminated scaffold after 2 months in vivo. The laminated bio-composite scaffolds can be applied to bone regeneration.

  20. Laminated electrospun nHA/PHB-composite scaffolds mimicking bone extracellular matrix for bone tissue engineering

    International Nuclear Information System (INIS)

    Chen, Zhuoyue; Song, Yue; Zhang, Jing; Liu, Wei; Cui, Jihong

    2017-01-01

    Electrospinning is an effective means to generate nano- to micro-scale polymer fibers resembling native extracellular matrix for tissue engineering. However, a major problem of electrospun materials is that limited pore size and porosity may prevent adequate cellular infiltration and tissue ingrowth. In this study, we first prepared thin layers of hydroxyapatite nanoparticle (nHA)/poly-hydroxybutyrate (PHB) via electrospinning. We then laminated the nHA/PHB thin layers to obtain a scaffold for cell seeding and bone tissue engineering. The results demonstrated that the laminated scaffold possessed optimized cell-loading capacity. Bone marrow mesenchymal stem cells (MSCs) exhibited better adherence, proliferation and osteogenic phenotypes on nHA/PHB scaffolds than on PHB scaffolds. Thereafter, we seeded MSCs onto nHA/PHB scaffolds to fabricate bone grafts. Histological observation showed osteoid tissue formation throughout the scaffold, with most of the scaffold absorbed in the specimens 2 months after implantation, and blood vessels ingrowth into the graft could be observed in the graft. We concluded that electrospun and laminated nanoscaled biocomposite scaffolds hold great therapeutic potential for bone regeneration. - Highlights: • We laminated the nHA/PHB layers to obtain a scaffold for bone tissue engineering. • The laminated scaffold performed optimized cell-loading capacity. • MSCs exhibited osteogenic phenotypes on the laminated scaffold. • Osteoid tissue formed throughout the laminated scaffold after 2 months in vivo. The laminated bio-composite scaffolds can be applied to bone regeneration.

  1. Reinforced nanohydroxyapatite/polyamide66 scaffolds by chitosan coating for bone tissue engineering.

    Science.gov (United States)

    Huang, Di; Zuo, Yi; Zou, Qin; Wang, Yanying; Gao, Shibo; Wang, Xiaoyan; Liu, Haohuai; Li, Yubao

    2012-01-01

    High porosity of scaffold is always accompanied by poor mechanical property; the aim of this study was to enhance the strength and modulus of the highly porous scaffold of nanohydroxyapatite/polyamide66 (n-HA/PA66) by coating chitosan (CS) and to investigate the effect of CS content on the scaffold physical properties and cytological properties. The results show that CS coating can reinforce the scaffold effectively. The compress modulus and strength of the CS coated n-HA/PA66 scaffolds are improved to 32.71 and 2.38 MPa, respectively, being about six times and five times of those of the uncoated scaffolds. Meanwhile, the scaffolds still exhibit a highly interconnected porous structure and the porosity is approximate about 78%, slightly lower than the value (84%) of uncoated scaffold. The cytological properties of scaffolds were also studied in vitro by cocultured with osteoblast-like MG63 cells. The cytological experiments demonstrate that the reinforced scaffolds display favorable cytocompatibility and have no significant difference with the uncoated n-HA/PA66 scaffolds. The CS reinforced n-HA/PA66 scaffolds can meet the basic mechanical requirement of bone tissue engineering scaffold, presenting a potential for biomedical application in bone reconstruction and repair. Copyright © 2011 Wiley Periodicals, Inc.

  2. PCL-coated hydroxyapatite scaffold derived from cuttlefish bone: In vitro cell culture studies

    International Nuclear Information System (INIS)

    Milovac, Dajana; Gamboa-Martínez, Tatiana C.; Ivankovic, Marica; Gallego Ferrer, Gloria; Ivankovic, Hrvoje

    2014-01-01

    In the present study, we examined the potential of using highly porous poly(ε-caprolactone) (PCL)-coated hydroxyapatite (HAp) scaffold derived from cuttlefish bone for bone tissue engineering applications. The cell culture studies were performed in vitro with preosteoblastic MC3T3-E1 cells in static culture conditions. Comparisons were made with uncoated HAp scaffold. The attachment and spreading of preosteoblasts on scaffolds were observed by Live/Dead staining Kit. The cells grown on the HAp/PCL composite scaffold exhibited greater spreading than cells grown on the HAp scaffold. DNA quantification and scanning electron microscopy (SEM) confirmed a good proliferation of cells on the scaffolds. DNA content on the HAp/PCL scaffold was significantly higher compared to porous HAp scaffolds. The amount of collagen synthesis was determined using a hydroxyproline assay. The osteoblastic differentiation of the cells was evaluated by determining alkaline phosphatase (ALP) activity and collagen type I secretion. Furthermore, cell spreading and cell proliferation within scaffolds were observed using a fluorescence microscope. - Highlights: • Hydroxyapatite/poly(ε-caprolactone) scaffold with interconnected pores was prepared • Cytotoxicity test showed that the scaffold was not cytotoxic towards MC3T3-E1 cells • The scaffold supported the attachment, proliferation and differentiation of cells • A 3D cell colonization was confirmed using the fluorescence microscopy • The scaffold might be a promising candidate for bone tissue engineering

  3. 3D conductive nanocomposite scaffold for bone tissue engineering

    Directory of Open Access Journals (Sweden)

    Shahini A

    2013-12-01

    Full Text Available Aref Shahini,1 Mostafa Yazdimamaghani,2 Kenneth J Walker,2 Margaret A Eastman,3 Hamed Hatami-Marbini,4 Brenda J Smith,5 John L Ricci,6 Sundar V Madihally,2 Daryoosh Vashaee,1 Lobat Tayebi2,7 1School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, 2School of Chemical Engineering, 3Department of Chemistry, 4School of Mechanical and Aerospace Engineering, 5Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK, USA; 6Department of Biomaterials and Biomimetics, New York University, New York, NY; 7School of Material Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK, USA Abstract: Bone healing can be significantly expedited by applying electrical stimuli in the injured region. Therefore, a three-dimensional (3D ceramic conductive tissue engineering scaffold for large bone defects that can locally deliver the electrical stimuli is highly desired. In the present study, 3D conductive scaffolds were prepared by employing a biocompatible conductive polymer, ie, poly(3,4-ethylenedioxythiophene poly(4-styrene sulfonate (PEDOT:PSS, in the optimized nanocomposite of gelatin and bioactive glass. For in vitro analysis, adult human mesenchymal stem cells were seeded in the scaffolds. Material characterizations using hydrogen-1 nuclear magnetic resonance, in vitro degradation, as well as thermal and mechanical analysis showed that incorporation of PEDOT:PSS increased the physiochemical stability of the composite, resulting in improved mechanical properties and biodegradation resistance. The outcomes indicate that PEDOT:PSS and polypeptide chains have close interaction, most likely by forming salt bridges between arginine side chains and sulfonate groups. The morphology of the scaffolds and cultured human mesenchymal stem cells were observed and analyzed via scanning electron microscope, micro-computed tomography, and confocal fluorescent

  4. Cell-matrix mechanical interaction in electrospun polymeric scaffolds for tissue engineering: Implications for scaffold design and performance.

    Science.gov (United States)

    Kennedy, Kelsey M; Bhaw-Luximon, Archana; Jhurry, Dhanjay

    2017-03-01

    Engineered scaffolds produced by electrospinning of biodegradable polymers offer a 3D, nanofibrous environment with controllable structural, chemical, and mechanical properties that mimic the extracellular matrix of native tissues and have shown promise for a number of tissue engineering applications. The microscale mechanical interactions between cells and electrospun matrices drive cell behaviors including migration and differentiation that are critical to promote tissue regeneration. Recent developments in understanding these mechanical interactions in electrospun environments are reviewed, with emphasis on how fiber geometry and polymer structure impact on the local mechanical properties of scaffolds, how altering the micromechanics cues cell behaviors, and how, in turn, cellular and extrinsic forces exerted on the matrix mechanically remodel an electrospun scaffold throughout tissue development. Techniques used to measure and visualize these mechanical interactions are described. We provide a critical outlook on technological gaps that must be overcome to advance the ability to design, assess, and manipulate the mechanical environment in electrospun scaffolds toward constructs that may be successfully applied in tissue engineering and regenerative medicine. Tissue engineering requires design of scaffolds that interact with cells to promote tissue development. Electrospinning is a promising technique for fabricating fibrous, biomimetic scaffolds. Effects of electrospun matrix microstructure and biochemical properties on cell behavior have been extensively reviewed previously; here, we consider cell-matrix interaction from a mechanical perspective. Micromechanical properties as a driver of cell behavior has been well established in planar substrates, but more recently, many studies have provided new insights into mechanical interaction in fibrillar, electrospun environments. This review provides readers with an overview of how electrospun scaffold mechanics and

  5. Development of nanofibrous scaffolds containing gum tragacanth/poly (ε-caprolactone) for application as skin scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Ranjbar-Mohammadi, Marziyeh [Textile Engineering Department, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Bahrami, S. Hajir, E-mail: hajirb@aut.ac.ir [Textile Engineering Department, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Center for excellence Modern Textile Characterization, Tehran (Iran, Islamic Republic of)

    2015-03-01

    Outstanding wound healing activity of gum tragacanth (GT) and higher mechanical strength of poly (ε-caprolactone) (PCL) may produce an excellent nanofibrous patch for either skin tissue engineering or wound dressing application. PCL/GT scaffold containing different concentrations of PCL with different blend ratios of GT/PCL was produced using 90% acetic acid as solvent. The results demonstrated that the PCL/GT (3:1.5) with PCL concentration of 20% (w/v) produced nanofibers with proper morphology. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were utilized to characterize the nanofibers. Surface wettability, functional groups analysis, porosity and tensile properties of nanofibers were evaluated. Morphological characterization showed that the addition of GT to PCL solution results in decreasing the average diameter of the PCL/GT nanofibers. However, the hydrophilicity increased in the PCL/GT nanofibers. Slight increase in melting peaks was observed due to the blending of PCL with GT nanofibers. PCL/GT nanofibers were used for in vitro cell culture of human fibroblast cell lines AGO and NIH 3T3 fibroblast cells. MTT assay and SEM results showed that the biocomposite PCL/GT mats enhanced the fibroblast adhesion and proliferation compared to PCL scaffolds. The antibacterial activity of PCL/GT and GT nanofibers against Staphylococcus aureus and Pseudomonas aeruginosa was also examined. - Highlights: • A new skin tissue engineering scaffold from poly (ε-caprolactone) (PCL) and gum tragacanth (GT) has been developed. • These scaffolds might be an effectual simulator of the structure and composition of native skin. • Very slight increase in melting peaks was observed due to the blending of PCL with GT nanofibers. • Biodegradation, water uptake and hydrophilicity properties of these scaffolds showed that produced scaffolds were adherent. • The electrospun PCL/GT scaffold can promote the skin regeneration of full

  6. Development of nanofibrous scaffolds containing gum tragacanth/poly (ε-caprolactone) for application as skin scaffolds

    International Nuclear Information System (INIS)

    Ranjbar-Mohammadi, Marziyeh; Bahrami, S. Hajir

    2015-01-01

    Outstanding wound healing activity of gum tragacanth (GT) and higher mechanical strength of poly (ε-caprolactone) (PCL) may produce an excellent nanofibrous patch for either skin tissue engineering or wound dressing application. PCL/GT scaffold containing different concentrations of PCL with different blend ratios of GT/PCL was produced using 90% acetic acid as solvent. The results demonstrated that the PCL/GT (3:1.5) with PCL concentration of 20% (w/v) produced nanofibers with proper morphology. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were utilized to characterize the nanofibers. Surface wettability, functional groups analysis, porosity and tensile properties of nanofibers were evaluated. Morphological characterization showed that the addition of GT to PCL solution results in decreasing the average diameter of the PCL/GT nanofibers. However, the hydrophilicity increased in the PCL/GT nanofibers. Slight increase in melting peaks was observed due to the blending of PCL with GT nanofibers. PCL/GT nanofibers were used for in vitro cell culture of human fibroblast cell lines AGO and NIH 3T3 fibroblast cells. MTT assay and SEM results showed that the biocomposite PCL/GT mats enhanced the fibroblast adhesion and proliferation compared to PCL scaffolds. The antibacterial activity of PCL/GT and GT nanofibers against Staphylococcus aureus and Pseudomonas aeruginosa was also examined. - Highlights: • A new skin tissue engineering scaffold from poly (ε-caprolactone) (PCL) and gum tragacanth (GT) has been developed. • These scaffolds might be an effectual simulator of the structure and composition of native skin. • Very slight increase in melting peaks was observed due to the blending of PCL with GT nanofibers. • Biodegradation, water uptake and hydrophilicity properties of these scaffolds showed that produced scaffolds were adherent. • The electrospun PCL/GT scaffold can promote the skin regeneration of full

  7. Effects of scaffold surface morphology on cell adhesion and survival rate in vitreous cryopreservation of tenocyte-scaffold constructs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhi [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China); Department of Bone and Joint Surgery, The affiliated hospital of Luzhou Medical College, Luzhou 646000 (China); Qing, Quan [Sichuan College of Traditional Chinese Medicine, Mianyang 621000 (China); Regenerative Medicine Research Center, West China Hospital of Sichuan University, Chengdu 610041 (China); Chen, Xi; Liu, Cheng-Jun; Luo, Jing-Cong [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China); Hu, Jin-Lian [Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong (China); Qin, Ting-Wu, E-mail: tingwuqin@hotmail.com [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China)

    2016-12-01

    Highlights: • The shapes of tenocytes varied when seeded on different surface of scaffolds. • Tenocytes were flat on smooth surface and spindle on micro-grooved surface. • Tenocytes were ellipse or spindle on porous surface. • Tenocytes got varying adhesion shape and elongation index on varying surfaces. • The tenocyte survival on porous surface was superior to the other two groups. - Abstract: The purpose of this study was to investigate the effects of scaffold surface morphology on cell adhesion and survival rate in vitreous cryopreservation of tenocyte-scaffold constructs. Tenocytes were obtained from tail tendons of rats. Polydimethylsiloxane (PDMS) was used to fabricate three types of scaffolds with varying surface morphological characteristics, i.e., smooth, micro-grooved, and porous surfaces, respectively. The tenocytes were seeded on the surfaces of the scaffolds to form tenocyte-scaffold constructs. The constructs were cryopreserved in a vitreous cryoprotectant (CPA) with a multi-step protocol. The cell adhesion to scaffolds was observed with electronic scanning microscopy (SEM). The elongation index of the living tenocytes and ratio of live/dead cell number were examined based on a live/dead dual fluorescent staining technique, and the survival rate of tenocytes was studied with flow cytometry (FC). The results showed the shapes of tenocytes varied between the different groups: flat or polygonal (on smooth surface), spindle (on micro-grooved surface), and spindle or ellipse (on porous surface). After thawing, the porous surface got the most living tenocytes and a higher survival rate, suggesting its potential application for vitreous cryopreservation of engineered tendon constructs.

  8. Polycaprolactone Scaffolds Fabricated via Bioextrusion for Tissue Engineering Applications

    Directory of Open Access Journals (Sweden)

    Marco Domingos

    2009-01-01

    Full Text Available The most promising approach in Tissue Engineering involves the seeding of porous, biocompatible/biodegradable scaffolds, with donor cells to promote tissue regeneration. Additive biomanufacturing processes are increasingly recognized as ideal techniques to produce 3D structures with optimal pore size and spatial distribution, providing an adequate mechanical support for tissue regeneration while shaping in-growing tissues. This paper presents a novel extrusion-based system to produce 3D scaffolds with controlled internal/external geometry for TE applications.The BioExtruder is a low-cost system that uses a proper fabrication code based on the ISO programming language enabling the fabrication of multimaterial scaffolds. Poly(ε-caprolactone was the material chosen to produce porous scaffolds, made by layers of directionally aligned microfilaments. Chemical, morphological, and in vitro biological evaluation performed on the polymeric constructs revealed a high potential of the BioExtruder to produce 3D scaffolds with regular and reproducible macropore architecture, without inducing relevant chemical and biocompatibility alterations of the material.

  9. Injectable biomimetic liquid crystalline scaffolds enhance muscle stem cell transplantation

    Science.gov (United States)

    Sleep, Eduard; McClendon, Mark T.; Preslar, Adam T.; Chen, Charlotte H.; Sangji, M. Hussain; Pérez, Charles M. Rubert; Haynes, Russell D.; Meade, Thomas J.; Blau, Helen M.; Stupp, Samuel I.

    2017-01-01

    Muscle stem cells are a potent cell population dedicated to efficacious skeletal muscle regeneration, but their therapeutic utility is currently limited by mode of delivery. We developed a cell delivery strategy based on a supramolecular liquid crystal formed by peptide amphiphiles (PAs) that encapsulates cells and growth factors within a muscle-like unidirectionally ordered environment of nanofibers. The stiffness of the PA scaffolds, dependent on amino acid sequence, was found to determine the macroscopic degree of cell alignment templated by the nanofibers in vitro. Furthermore, these PA scaffolds support myogenic progenitor cell survival and proliferation and they can be optimized to induce cell differentiation and maturation. We engineered an in vivo delivery system to assemble scaffolds by injection of a PA solution that enabled coalignment of scaffold nanofibers with endogenous myofibers. These scaffolds locally retained growth factors, displayed degradation rates matching the time course of muscle tissue regeneration, and markedly enhanced the engraftment of muscle stem cells in injured and noninjured muscles in mice. PMID:28874575

  10. Maternal scaffolding behavior: links with parenting style and maternal education.

    Science.gov (United States)

    Carr, Amanda; Pike, Alison

    2012-03-01

    The purpose of this study was to specify the relationship between positive and harsh parenting and maternal scaffolding behavior. A 2nd aim was to disentangle the effects of maternal education and parenting quality, and a 3rd aim was to test whether parenting quality mediated the association between maternal education and scaffolding practices. We examined associations between positive and harsh parenting practices and contingent and noncontingent tutoring strategies. Ninety-six mother-child dyads (49 boys, 47 girls) from working- and middle-class English families participated. Mothers reported on parenting quality at Time 1 when children were 5 years old and again approximately 5 years later at Time 2. Mother-child pairs were observed working together on a block design task at Time 2, and interactions were coded for contingent (contingent shifting) and noncontingent (fixed failure feedback) dimensions of maternal scaffolding behavior. Positive and harsh parenting accounted for variance in contingent behavior over and above maternal education, whereas only harsh parenting accounted for unique variance in noncontingent scaffolding practices. Our findings provide new evidence for a more differentiated model of the relation between general parenting quality and specific scaffolding behaviors. PsycINFO Database Record (c) 2012 APA, all rights reserved.

  11. Manufacturing of calcium phosphate scaffolds by pseudomorphic transformation of gypsum

    Energy Technology Data Exchange (ETDEWEB)

    Araujo Batista, H. de.; Batista Cardoso, M.; Sales Vasconcelos, A.; Vinicius Lia Fook, M.; Rodriguez Barbero, M. A.; Garcia Carrodeguas, R.

    2016-08-01

    Carbonated hydroxyapatite (CHAp) and β-tricalcium phosphate (β-TCP) have been employed for decades as constituents of scaffolds for bone regeneration because they chemically resemble bone mineral. In this study, the feasibility to manufacture CHAp/β-TCP scaffolds by pseudomorphic transformation of casted blocks of gypsum was investigated. The transformation was carried out by immersing the precursor gypsum block in 1 M (NH{sub 4}){sub 2}HPO{sub 4}/1.33 M NH{sub 4}OH solution with liquid/solid ratio of 10 mL/g and autoclaving at 120 degree centigrade and 203 kPa (2 atm) for 3 h at least. Neither shape nor dimensions significantly changed during transformation. The composition of scaffolds treated for 3 h was 70 wt.% CHAp and 30 wt.% β-TCP, and their compressive and diametral compressive strengths were 6.5 ± 0.7 and 5.3 ±0.7 MPa, respectively. By increasing the time of treatment to 6 h, the composition of the scaffold enriched in β-TCP (60 wt.% CHAp and 40 wt.% β-TCP) but its compressive and diametral compressive strengths were not significantly affected (6.7 ± 0.9 and 5.4 ± 0.6 MPa, respectively). On the basis of the results obtained, it was concluded that this route is a good approach to the manufacturing of biphasic (CHAp/β-TCP) scaffolds from previously shaped pieces of gypsum. (Author)

  12. Emerging bone tissue engineering via Polyhydroxyalkanoate (PHA)-based scaffolds.

    Science.gov (United States)

    Lim, Janice; You, Mingliang; Li, Jian; Li, Zibiao

    2017-10-01

    Polyhydroxyalkanoates (PHAs) are a class of biodegradable polymers derived from microorganisms. On top of their biodegradability and biocompatibility, different PHA types can contribute to varying mechanical and chemical properties. This has led to increasing attention to the use of PHAs in numerous biomedical applications over the past few decades. Bone tissue engineering refers to the regeneration of new bone through providing mechanical support while inducing cell growth on the PHA scaffolds having a porous structure for tissue regeneration. This review first introduces the various properties PHA scaffold that make them suitable for bone tissue engineering such as biocompatibility, biodegradability, mechanical properties as well as vascularization. The typical fabrication techniques of PHA scaffolds including electrospinning, salt-leaching and solution casting are further discussed, followed by the relatively new technology of using 3D printing in PHA scaffold fabrication. Finally, the recent progress of using different types of PHAs scaffold in bone tissue engineering applications are summarized in intrinsic PHA/blends forms or as composites with other polymeric or inorganic hybrid materials. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Novel scaffold design with multi-grooved PLA fibers

    International Nuclear Information System (INIS)

    Chung, Sangwon; King, Martin W; Gamcsik, Mike P

    2011-01-01

    A novel prototype nonwoven textile structure containing polylactide (PLA) multigrooved fibers has been proposed as a possible scaffold material for superior cell attachment and proliferation. Grooved cross-sectional fibers with larger surface area were obtained by a bi-component spinning system and the complete removal of the sacrificial component was confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray photon spectroscopy (XPS) analysis. These PLA nonwoven scaffolds containing the grooved fibers exhibited enhanced wettability, greater flexibility and tensile properties, and a larger surface area compared to a traditional PLA nonwoven fabric containing round fibers. To evaluate cellular attachment on the two types of PLA nonwoven scaffolds, NIH 3T3 fibroblasts were cultured for up to 12 days. It was evident that the initial cellular attachment was superior on the scaffold with grooved fibers, which was confirmed by MTT viability assay (p < 0.01) and SEM analysis. In the future, by modulating the size of the grooves on the fibers, such a scaffold material with a large surface area could serve as an alternative matrix for culturing different types of cells.

  14. Osteochondral tissue engineering: scaffolds, stem cells and applications

    Science.gov (United States)

    Nooeaid, Patcharakamon; Salih, Vehid; Beier, Justus P; Boccaccini, Aldo R

    2012-01-01

    Osteochondral tissue engineering has shown an increasing development to provide suitable strategies for the regeneration of damaged cartilage and underlying subchondral bone tissue. For reasons of the limitation in the capacity of articular cartilage to self-repair, it is essential to develop approaches based on suitable scaffolds made of appropriate engineered biomaterials. The combination of biodegradable polymers and bioactive ceramics in a variety of composite structures is promising in this area, whereby the fabrication methods, associated cells and signalling factors determine the success of the strategies. The objective of this review is to present and discuss approaches being proposed in osteochondral tissue engineering, which are focused on the application of various materials forming bilayered composite scaffolds, including polymers and ceramics, discussing the variety of scaffold designs and fabrication methods being developed. Additionally, cell sources and biological protein incorporation methods are discussed, addressing their interaction with scaffolds and highlighting the potential for creating a new generation of bilayered composite scaffolds that can mimic the native interfacial tissue properties, and are able to adapt to the biological environment. PMID:22452848

  15. In vitro evaluation of crosslinked electrospun fish gelatin scaffolds.

    Science.gov (United States)

    Gomes, S R; Rodrigues, G; Martins, G G; Henriques, C M R; Silva, J C

    2013-04-01

    Gelatin from cold water fish skin was electrospun, crosslinked and investigated as a substrate for the adhesion and proliferation of cells. Gelatin was first dissolved in either water or concentrated acetic acid and both solutions were successfully electrospun. Cross-linking was achieved via three different routes: glutaraldehyde vapor, genipin and dehydrothermal treatment. Solution's properties (surface tension, electrical conductivity and viscosity) and scaffold's properties (chemical bonds, weight loss and fiber diameters) were measured. Cellular viability was analyzed culturing 3T3 fibroblasts plated on the scaffolds and grown up to 7 days. The cells were fixed and observed with SEM or stained for DNA and F-actin and observed with confocal microscopy. In all scaffolds, the cells attached and spread with varying degrees. The evaluation of cell viability showed proliferation of cells until confluence in scaffolds crosslinked by glutaraldehyde and genipin; however the rate of growth in genipin crosslinked scaffolds was slow, recovering only by day five. The results using the dehydrothermal treatment were the less satisfactory. Our results show that glutaraldehyde treated fish gelatin is the most suitable substrate, of the three studied, for fibroblast adhesion and proliferation. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Decellularized Human Skeletal Muscle as Biologic Scaffold for Reconstructive Surgery

    Directory of Open Access Journals (Sweden)

    Andrea Porzionato

    2015-07-01

    Full Text Available Engineered skeletal muscle tissues have been proposed as potential solutions for volumetric muscle losses, and biologic scaffolds have been obtained by decellularization of animal skeletal muscles. The aim of the present work was to analyse the characteristics of a biologic scaffold obtained by decellularization of human skeletal muscles (also through comparison with rats and rabbits and to evaluate its integration capability in a rabbit model with an abdominal wall defect. Rat, rabbit and human muscle samples were alternatively decellularized with two protocols: n.1, involving sodium deoxycholate and DNase I; n.2, trypsin-EDTA and Triton X-NH4OH. Protocol 2 proved more effective, removing all cellular material and maintaining the three-dimensional networks of collagen and elastic fibers. Ultrastructural analyses with transmission and scanning electron microscopy confirmed the preservation of collagen, elastic fibres, glycosaminoglycans and proteoglycans. Implantation of human scaffolds in rabbits gave good results in terms of integration, although recellularization by muscle cells was not completely achieved. In conclusion, human skeletal muscles may be effectively decellularized to obtain scaffolds preserving the architecture of the extracellular matrix and showing mechanical properties suitable for implantation/integration. Further analyses will be necessary to verify the suitability of these scaffolds for in vitro recolonization by autologous cells before in vivo implantation.

  17. Fabrication and characterization of calcium phosphate cement scaffolds

    International Nuclear Information System (INIS)

    Sousa, E. de; Motisuke, M.; Bertran, C.A.

    2011-01-01

    In Tissue Engineering, the need for scaffolds which are capable of guiding the organization, differentiation and growth of cells leading to the formation of new tissues is highly relevant. For the development of new scaffolds focused on bone tissue therapy, calcium phosphate cements (CPC) have great potential, because besides their resorbability, they present morphology and chemical composition similar to the bone mineral phase. Moreover, there are several processing techniques to produce ceramic scaffolds: polymeric sponge replication, incorporation of organic material into the ceramic powder, gelcasting, emulsion, among others. The aim of this work was to obtain CPCs scaffolds by using two techniques, emulsion and gelcasting. The scaffolds were characterized by their physical and mechanical properties and the crystalline phases formed after the setting reaction of cement were determined by X-ray diffraction. The samples obtained by both methods presented porosity between 61-65% and the microstructure consists of nearly spherical pores (d5o = 50-100 μm). The mechanical strength of the samples ranged from 5.5 to 1.5 MPa. The crystalline phases found were monetite (CaHPO 4 ) and brushite (CaHPO 4 2H 2 O). (author)

  18. Computer aided design of architecture of degradable tissue engineering scaffolds.

    Science.gov (United States)

    Heljak, M K; Kurzydlowski, K J; Swieszkowski, W

    2017-11-01

    One important factor affecting the process of tissue regeneration is scaffold stiffness loss, which should be properly balanced with the rate of tissue regeneration. The aim of the research reported here was to develop a computer tool for designing the architecture of biodegradable scaffolds fabricated by melt-dissolution deposition systems (e.g. Fused Deposition Modeling) to provide the required scaffold stiffness at each stage of degradation/regeneration. The original idea presented in the paper is that the stiffness of a tissue engineering scaffold can be controlled during degradation by means of a proper selection of the diameter of the constituent fibers and the distances between them. This idea is based on the size-effect on degradation of aliphatic polyesters. The presented computer tool combines a genetic algorithm and a diffusion-reaction model of polymer hydrolytic degradation. In particular, we show how to design the architecture of scaffolds made of poly(DL-lactide-co-glycolide) with the required Young's modulus change during hydrolytic degradation.

  19. Multilayer porous UHMWPE scaffolds for bone defects replacement.

    Science.gov (United States)

    Maksimkin, A V; Senatov, F S; Anisimova, N Yu; Kiselevskiy, M V; Zalepugin, D Yu; Chernyshova, I V; Tilkunova, N A; Kaloshkin, S D

    2017-04-01

    Reconstruction of the structural integrity of the damaged bone tissue is an urgent problem. UHMWPE may be potentially used for the manufacture of porous implants simulating as closely as possible the porous cancellous bone tissue. But the extremely high molecular weight of the polymer does not allow using traditional methods of foaming. Porous and multilayer UHMWPE scaffolds with nonporous bulk layer and porous layer that mimics cancellous bone architecture were obtained by solid-state mixing, thermopressing and washing in subcritical water. Structural and mechanical properties of the samples were studied. Porous UHMWPE samples were also studied in vitro and in vivo. The pores of UHMWPE scaffold are open and interconnected. Volume porosity of the obtained samples was 79±2%; the pore size range was 80-700μm. Strong connection of the two layers in multilayer UHMWPE scaffolds was observed with decreased number of fusion defects. Functionality of implants based on multilayer UHMWPE scaffolds is provided by the fixation of scaffolds in the bone defect through ingrowths of the connective tissue into the pores, which ensures the maintenance of the animals' mobility. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Proangiogenic scaffolds as functional templates for cardiac tissue engineering.

    Science.gov (United States)

    Madden, Lauran R; Mortisen, Derek J; Sussman, Eric M; Dupras, Sarah K; Fugate, James A; Cuy, Janet L; Hauch, Kip D; Laflamme, Michael A; Murry, Charles E; Ratner, Buddy D

    2010-08-24

    We demonstrate here a cardiac tissue-engineering strategy addressing multicellular organization, integration into host myocardium, and directional cues to reconstruct the functional architecture of heart muscle. Microtemplating is used to shape poly(2-hydroxyethyl methacrylate-co-methacrylic acid) hydrogel into a tissue-engineering scaffold with architectures driving heart tissue integration. The construct contains parallel channels to organize cardiomyocyte bundles, supported by micrometer-sized, spherical, interconnected pores that enhance angiogenesis while reducing scarring. Surface-modified scaffolds were seeded with human ES cell-derived cardiomyocytes and cultured in vitro. Cardiomyocytes survived and proliferated for 2 wk in scaffolds, reaching adult heart densities. Cardiac implantation of acellular scaffolds with pore diameters of 30-40 microm showed angiogenesis and reduced fibrotic response, coinciding with a shift in macrophage phenotype toward the M2 state. This work establishes a foundation for spatially controlled cardiac tissue engineering by providing discrete compartments for cardiomyocytes and stroma in a scaffold that enhances vascularization and integration while controlling the inflammatory response.

  1. Solvent/Non-Solvent Sintering To Make Microsphere Scaffolds

    Science.gov (United States)

    Laurencin, Cato T.; Brown, Justin L.; Nair, Lakshmi

    2011-01-01

    A solvent/non-solvent sintering technique has been devised for joining polymeric microspheres to make porous matrices for use as drug-delivery devices or scaffolds that could be seeded with cells for growing tissues. Unlike traditional sintering at elevated temperature and pressure, this technique is practiced at room temperature and pressure and, therefore, does not cause thermal degradation of any drug, protein, or other biochemical with which the microspheres might be loaded to impart properties desired in a specific application. Also, properties of scaffolds made by this technique are more reproducible than are properties of comparable scaffolds made by traditional sintering. The technique involves the use of two miscible organic liquids: one that is and one that is not a solvent for the affected polymer. The polymeric microspheres are placed in a mold having the size and shape of the desired scaffold, then the solvent/non-solvent mixture is poured into the mold to fill the void volume between the microspheres, then the liquid mixture is allowed to evaporate. Some of the properties of the resulting scaffold can be tailored through choice of the proportions of the liquids and the diameter of the microspheres.

  2. Novel Resorbable and Osteoconductive Calcium Silicophosphate Scaffold Induced Bone Formation

    Directory of Open Access Journals (Sweden)

    Patricia Ros-Tárraga

    2016-09-01

    Full Text Available This aim of this research was to develop a novel ceramic scaffold to evaluate the response of bone after ceramic implantation in New Zealand (NZ rabbits. Ceramics were prepared by the polymer replication method and inserted into NZ rabbits. Macroporous scaffolds with interconnected round-shaped pores (0.5–1.5 mm = were prepared. The scaffold acted as a physical support where cells with osteoblastic capability were found to migrate, develop processes, and newly immature and mature bone tissue colonized on the surface (initially and in the material’s interior. The new ceramic induced about 62.18% ± 2.28% of new bone and almost complete degradation after six healing months. An elemental analysis showed that the gradual diffusion of Ca and Si ions from scaffolds into newly formed bone formed part of the biomaterial’s resorption process. Histological and radiological studies demonstrated that this porous ceramic scaffold showed biocompatibility and excellent osteointegration and osteoinductive capacity, with no interposition of fibrous tissue between the implanted material and the hematopoietic bone marrow interphase, nor any immune response after six months of implantation. No histological changes were observed in the various organs studied (para-aortic lymph nodes, liver, kidney and lung as a result of degradation products being released.

  3. Surface-modified functionalized polycaprolactone scaffolds for bone repair

    DEFF Research Database (Denmark)

    Jensen, Jonas; Rölfing, Jan Hendrik Duedal; Svend Le, Dang Quang

    2014-01-01

    A porcine calvaria defect study was carried out to investigate the bone repair potential of three-dimensional (3D)-printed poly-ε-caprolactone (PCL) scaffolds embedded with nanoporous PCL. A microscopic grid network was created by rapid prototyping making a 3D-fused deposition model (FDM-PCL). Af......A porcine calvaria defect study was carried out to investigate the bone repair potential of three-dimensional (3D)-printed poly-ε-caprolactone (PCL) scaffolds embedded with nanoporous PCL. A microscopic grid network was created by rapid prototyping making a 3D-fused deposition model (FDM......-PCL). Afterward, the FDM-PCL scaffolds were infused with a mixture of PCL, water, and 1,4-dioxane and underwent a thermal-induced phase separation (TIPS) followed by lyophilization. The TIPS process lead to a nanoporous structure shielded by the printed microstructure (NSP-PCL). Sixteen Landrace pigs were divided...... into two groups with 8 and 12 weeks follow-up, respectively. A total of six nonpenetrating holes were drilled in the calvaria of each animal. The size of the cylindrical defects was h 10 mm and Ø 10 mm. The defects were distributed randomly using following groups: (a) NSP-PCL scaffold, (b) FDM-PCL scaffold...

  4. Potential of Cognitive Computing and Cognitive Systems

    Science.gov (United States)

    Noor, Ahmed K.

    2015-01-01

    Cognitive computing and cognitive technologies are game changers for future engineering systems, as well as for engineering practice and training. They are major drivers for knowledge automation work, and the creation of cognitive products with higher levels of intelligence than current smart products. This paper gives a brief review of cognitive computing and some of the cognitive engineering systems activities. The potential of cognitive technologies is outlined, along with a brief description of future cognitive environments, incorporating cognitive assistants - specialized proactive intelligent software agents designed to follow and interact with humans and other cognitive assistants across the environments. The cognitive assistants engage, individually or collectively, with humans through a combination of adaptive multimodal interfaces, and advanced visualization and navigation techniques. The realization of future cognitive environments requires the development of a cognitive innovation ecosystem for the engineering workforce. The continuously expanding major components of the ecosystem include integrated knowledge discovery and exploitation facilities (incorporating predictive and prescriptive big data analytics); novel cognitive modeling and visual simulation facilities; cognitive multimodal interfaces; and cognitive mobile and wearable devices. The ecosystem will provide timely, engaging, personalized / collaborative, learning and effective decision making. It will stimulate creativity and innovation, and prepare the participants to work in future cognitive enterprises and develop new cognitive products of increasing complexity. http://www.aee.odu.edu/cognitivecomp

  5. Monolithic three-dimensional electrochemical energy storage system on aerogel or nanotube scaffold

    Science.gov (United States)

    Farmer, Joseph C; Stadermann, Michael

    2013-11-12

    A monolithic three-dimensional electrochemical energy storage system is provided on an aerogel or nanotube scaffold. An anode, separator, cathode, and cathodic current collector are deposited on the aerogel or nanotube scaffold.

  6. A gelatin composite scaffold strengthened by drug-loaded halloysite nanotubes.

    Science.gov (United States)

    Ji, Lijun; Qiao, Wei; Zhang, Yuheng; Wu, Huayu; Miao, Shiyong; Cheng, Zhilin; Gong, Qianming; Liang, Ji; Zhu, Aiping

    2017-09-01

    Mechanical properties and anti-infection are two of the most concerned issues for artificial bone grafting materials. Bone regeneration porous scaffolds with sustained drug release were developed by freeze-drying the mixture of nanosized drug-loaded halloysite nanotubes (HNTs) and gelatin. The scaffolds showed porous structure and excellent biocompatibility. The mechanical properties of the obtained composite scaffolds were enhanced significantly by HNTs to >300%, comparing to those of gelatin scaffold, and match to those of natural cancellous bones. The ibuprofen-loaded HNTs incorporated in the scaffolds allowed extended drug release over 100h, comparing to 8h when directly mixed the drug into the gelatin scaffold. The biological properties of the composite scaffolds were investigated by culturing MG63 cells on them. The HNTs/gelatin scaffolds with excellent mechanical properties and sustained drug release could be a promising artificial bone grating material. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Influence of electrospun scaffolds prepared from distinct polymers on proliferation and viability of endothelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Matveeva, V. G., E-mail: matveeva-vg@mail.ru; Antonova, L. V., E-mail: antonova.la@mail.ru; Velikanova, E. A.; Sergeeva, E. A.; Krivkina, E. O.; Glushkova, T. V.; Kudryavtseva, Yu. A.; Barbarash, O. L.; Barbarash, L. S. [Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo, 650002 (Russian Federation)

    2015-10-27

    We compared electrospun nonwoven scaffolds from polylactic acid (PLA), polycaprolactone (PCL), and polyhydroxybutyrate/valerate (PHBV)/polycaprolactone (PHBV/PCL). The surface of PHBV/PCL and PCL scaffolds was highly porous and consisted of randomly distributed fibers, whilst the surface of PLA scaffolds consisted of thin straight fibers, which located more sparsely, forming large pores. Culture of EA.hy 926 endothelial cells on these scaffolds during 7 days and further fluorescent microscopy demonstrated that the surface of PHBV/PCL scaffolds was most favorable for efficient adhesion, proliferation, and viability of endothelial cells. The lowest proliferation rate and cell viability were detected on PLA scaffolds. Therefore, PHBV/PCL electrospun nonwoven scaffolds demonstrated the best results regarding endothelial cell proliferation and viability as compared to PCL and PLA scaffolds.

  8. Improved cell activity on biodegradable photopolymer scaffolds using titanate nanotube coatings

    Energy Technology Data Exchange (ETDEWEB)

    Beke, S., E-mail: szabolcs.beke@iit.it [Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Barenghi, R. [IEIIT, National Research Council (CNR), Via De Marini 6, 16149 Genova (Italy); Farkas, B.; Romano, I. [Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Kőrösi, L. [Department of Biotechnology, Nanophage Therapy Center, Enviroinvest Corporation, Kertváros u. 2, H-7632 Pécs (Hungary); Scaglione, S. [IEIIT, National Research Council (CNR), Via De Marini 6, 16149 Genova (Italy); Brandi, F. [Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Istituto Nazionale di Ottica, CNR, Via G. Moruzzi 1, 56124-Pisa (Italy)

    2014-11-01

    The development of bioactive materials is in the premise of tissue engineering. For several years, surface functionalization of scaffolds has been one of the most promising approaches to stimulate cellular activity and finally improve implant success. Herein, we describe the development of a bioactive composite scaffold composed of a biodegradable photopolymer scaffold and titanate nanotubes (TNTs). The biodegradable photopolymer scaffolds were fabricated by applying mask-projection excimer laser photocuring at 308 nm. TNTs were synthesized and then spin-coated on the porous scaffolds. Upon culturing fibroblast cells on scaffolds, we found that nanotubes coating affects cell viability and proliferation demonstrating that TNT coatings enhance cell growth on the scaffolds by further improving their surface topography. - Highlights: • Biodegradable scaffolds were produced by mask-assisted UV laser photocuring. • Titanate nanotube deposition was carried out without binding compounds or additives. • Titanate nanotube coatings enhanced cell viability and proliferation.

  9. Conducting Polymer Scaffolds for Hosting and Monitoring 3D Cell Culture

    KAUST Repository

    Inal, Sahika; Hama, Adel; Ferro, Magali; Pitsalidis, Charalampos; Oziat, Julie; Iandolo, Donata; Pappa, Anna-Maria; Hadida, Mikhael; Huerta, Miriam; Marchat, David; Mailley, Pascal; Owens, Ró isí n M.

    2017-01-01

    to their biocompatibility and tissue-like elasticity, which can be manipulated by inclusion of biopolymers such as collagen. Integration of a media perfusion tube inside the scaffold enables homogenous cell spreading and fluid transport throughout the scaffold, ensuring

  10. Alendronate-Eluting Biphasic Calcium Phosphate (BCP Scaffolds Stimulate Osteogenic Differentiation

    Directory of Open Access Journals (Sweden)

    Sung Eun Kim

    2015-01-01

    Full Text Available Biphasic calcium phosphate (BCP scaffolds have been widely used in orthopedic and dental fields as osteoconductive bone substitutes. However, BCP scaffolds are not satisfactory for the stimulation of osteogenic differentiation and maturation. To enhance osteogenic differentiation, we prepared alendronate- (ALN- eluting BCP scaffolds. The coating of ALN on BCP scaffolds was confirmed by scanning electron microscopy (FE-SEM, energy-dispersive X-ray spectroscopy (EDS, and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR. An in vitro release study showed that release of ALN from ALN-eluting BCP scaffolds was sustained for up to 28 days. In vitro results revealed that MG-63 cells grown on ALN-eluting BCP scaffolds exhibited increased ALP activity and calcium deposition and upregulated gene expression of Runx2, ALP, OCN, and OPN compared with the BCP scaffold alone. Therefore, this study suggests that ALN-eluting BCP scaffolds have the potential to effectively stimulate osteogenic differentiation.

  11. Image-Based Three-Dimensional Analysis to Characterize the Texture of Porous Scaffolds

    Directory of Open Access Journals (Sweden)

    Diana Massai

    2014-01-01

    Full Text Available The aim of the present study is to characterize the microstructure of composite scaffolds for bone tissue regeneration containing different ratios of chitosan/gelatin blend and bioactive glasses. Starting from realistic 3D models of the scaffolds reconstructed from micro-CT images, the level of heterogeneity of scaffold architecture is evaluated performing a lacunarity analysis. The results demonstrate that the presence of the bioactive glass component affects not only macroscopic features such as porosity, but mainly scaffold microarchitecture giving rise to structural heterogeneity, which could have an impact on the local cell-scaffold interaction and scaffold performances. The adopted approach allows to investigate the scale-dependent pore distribution within the scaffold and the related structural heterogeneity features, providing a comprehensive characterization of the scaffold texture.

  12. Surface-enrichment with hydroxyapatite nanoparticles in stereolithography-fabricated composite polymer scaffolds promotes bone repair

    NARCIS (Netherlands)

    Guillaume, O.; Geven, M. A.; Sprecher, C. M.; Stadelmann, V. A.; Grijpma, D. W.; Tang, T.T.; Qin, L.; Lai, Y.; Alini, M.; de Bruijn, J. D.; Yuan, H.; Richards, R.G.; Eglin, D.

    2017-01-01

    Fabrication of composite scaffolds using stereolithography (SLA) for bone tissue engineering has shown great promises. However, in order to trigger effective bone formation and implant integration, exogenous growth factors are commonly combined to scaffold materials. In this study, we fabricated

  13. A comparison of scaffold-free and scaffold-based reconstructed human skin models as alternatives to animal use.

    Science.gov (United States)

    Kinikoglu, Beste

    2017-12-01

    Tissue engineered full-thickness human skin substitutes have various applications in the clinic and in the laboratory, such as in the treatment of burns or deep skin defects, and as reconstructed human skin models in the safety testing of drugs and cosmetics and in the fundamental study of skin biology and pathology. So far, different approaches have been proposed for the generation of reconstructed skin, each with its own advantages and disadvantages. Here, the classic tissue engineering approach, based on cell-seeded polymeric scaffolds, is compared with the less-studied cell self-assembly approach, where the cells are coaxed to synthesise their own extracellular matrix (ECM). The resulting full-thickness human skin substitutes were analysed by means of histological and immunohistochemical analyses. It was found that both the scaffold-free and the scaffold-based skin equivalents successfully mimicked the functionality and morphology of native skin, with complete epidermal differentiation (as determined by the expression of filaggrin), the presence of a continuous basement membrane expressing collagen VII, and new ECM deposition by dermal fibroblasts. On the other hand, the scaffold-free model had a thicker epidermis and a significantly higher number of Ki67-positive proliferative cells, indicating a higher capacity for self-renewal, as compared to the scaffold-based model. 2017 FRAME.

  14. Electrospinning polymer blends for biomimetic scaffolds for ACL tissue engineering

    Science.gov (United States)

    Garcia, Vanessa Lizeth

    The anterior cruciate ligament (ACL) rupture is one of the most common knee injuries. Current ACL reconstructive strategies consist of using an autograft or an allograft to replace the ligament. However, limitations have led researchers to create tissue engineered grafts, known as scaffolds, through electrospinning. Scaffolds made of natural and synthetic polymer blends have the potential to promote cell adhesion while having strong mechanical properties. However, enzymes found in the knee are known to degrade tissues and affect the healing of intra-articular injuries. Results suggest that the natural polymers used in this study modify the thermal properties and tensile strength of the synthetic polymers when blended. Scanning electron microscopy display bead-free and enzyme biodegradability of the fibers. Raman spectroscopy confirms the presence of the natural and synthetic polymers in the scaffolds while, amino acid analysis present the types of amino acids and their concentrations found in the natural polymers.

  15. Annealing free, clean graphene transfer using alternative polymer scaffolds.

    Science.gov (United States)

    Wood, Joshua D; Doidge, Gregory P; Carrion, Enrique A; Koepke, Justin C; Kaitz, Joshua A; Datye, Isha; Behnam, Ashkan; Hewaparakrama, Jayan; Aruin, Basil; Chen, Yaofeng; Dong, Hefei; Haasch, Richard T; Lyding, Joseph W; Pop, Eric

    2015-02-06

    We examine the transfer of graphene grown by chemical vapor deposition (CVD) with polymer scaffolds of poly(methyl methacrylate) (PMMA), poly(lactic acid) (PLA), poly(phthalaldehyde) (PPA), and poly(bisphenol A carbonate) (PC). We find that optimally reactive PC scaffolds provide the cleanest graphene transfers without any annealing, after extensive comparison with optical microscopy, x-ray photoelectron spectroscopy, atomic force microscopy, and scanning tunneling microscopy. Comparatively, films transferred with PLA, PPA, PMMA/PC, and PMMA have a two-fold higher roughness and a five-fold higher chemical doping. Using PC scaffolds, we demonstrate the clean transfer of CVD multilayer graphene, fluorinated graphene, and hexagonal boron nitride. Our annealing free, PC transfers enable the use of atomically-clean nanomaterials in biomolecule encapsulation and flexible electronic applications.

  16. Living bacterial sacrificial porogens to engineer decellularized porous scaffolds.

    Directory of Open Access Journals (Sweden)

    Feng Xu

    Full Text Available Decellularization and cellularization of organs have emerged as disruptive methods in tissue engineering and regenerative medicine. Porous hydrogel scaffolds have widespread applications in tissue engineering, regenerative medicine and drug discovery as viable tissue mimics. However, the existing hydrogel fabrication techniques suffer from limited control over pore interconnectivity, density and size, which leads to inefficient nutrient and oxygen transport to cells embedded in the scaffolds. Here, we demonstrated an innovative approach to develop a new platform for tissue engineered constructs using live bacteria as sacrificial porogens. E.coli were patterned and cultured in an interconnected three-dimensional (3D hydrogel network. The growing bacteria created interconnected micropores and microchannels. Then, the scafold was decellularized, and bacteria were eliminated from the scaffold through lysing and washing steps. This 3D porous network method combined with bioprinting has the potential to be broadly applicable and compatible with tissue specific applications allowing seeding of stem cells and other cell types.

  17. 3D printing process of oxidized nanocellulose and gelatin scaffold.

    Science.gov (United States)

    Xu, Xiaodong; Zhou, Jiping; Jiang, Yani; Zhang, Qi; Shi, Hongcan; Liu, Dongfang

    2018-08-01

    For tissue engineering applications tissue scaffolds need to have a porous structure to meet the needs of cell proliferation/differentiation, vascularisation and sufficient mechanical strength for the specific tissue. Here we report the results of a study of the 3D printing process for composite materials based on oxidized nanocellulose and gelatin, that was optimised through measuring rheological properties of different batches of materials after different crosslinking times, simulation of the pneumatic extrusion process and 3D scaffolds fabrication with Solidworks Flow Simulation, observation of its porous structure by SEM, measurement of pressure-pull performance, and experiments aimed at finding out the vitro cytotoxicity and cell morphology. The materials printed are highly porous scaffolds with good mechanical properties.

  18. Design properties of hydrogel tissue-engineering scaffolds

    Science.gov (United States)

    Zhu, Junmin; Marchant, Roger E

    2011-01-01

    This article summarizes the recent progress in the design and synthesis of hydrogels as tissue-engineering scaffolds. Hydrogels are attractive scaffolding materials owing to their highly swollen network structure, ability to encapsulate cells and bioactive molecules, and efficient mass transfer. Various polymers, including natural, synthetic and natural/synthetic hybrid polymers, have been used to make hydrogels via chemical or physical crosslinking. Recently, bioactive synthetic hydrogels have emerged as promising scaffolds because they can provide molecularly tailored biofunctions and adjustable mechanical properties, as well as an extracellular matrix-like microenvironment for cell growth and tissue formation. This article addresses various strategies that have been explored to design synthetic hydrogels with extracellular matrix-mimetic bioactive properties, such as cell adhesion, proteolytic degradation and growth factor-binding. PMID:22026626

  19. Design and 3D Printing of Scaffolds and Tissues

    Directory of Open Access Journals (Sweden)

    Jia An

    2015-06-01

    Full Text Available A growing number of three-dimensional (3D-printing processes have been applied to tissue engineering. This paper presents a state-of-the-art study of 3D-printing technologies for tissue-engineering applications, with particular focus on the development of a computer-aided scaffold design system; the direct 3D printing of functionally graded scaffolds; the modeling of selective laser sintering (SLS and fused deposition modeling (FDM processes; the indirect additive manufacturing of scaffolds, with both micro and macro features; the development of a bioreactor; and 3D/4D bioprinting. Technological limitations will be discussed so as to highlight the possibility of future improvements for new 3D-printing methodologies for tissue engineering.

  20. Fabrication of scaffolds in tissue engineering: A review

    Science.gov (United States)

    Zhao, Peng; Gu, Haibing; Mi, Haoyang; Rao, Chengchen; Fu, Jianzhong; Turng, Lih-sheng

    2018-03-01

    Tissue engineering (TE) is an integrated discipline that involves engineering and natural science in the development of biological materials to replace, repair, and improve the function of diseased or missing tissues. Traditional medical and surgical treatments have been reported to have side effects on patients caused by organ necrosis and tissue loss. However, engineered tissues and organs provide a new way to cure specific diseases. Scaffold fabrication is an important step in the TE process. This paper summarizes and reviews the widely used scaffold fabrication methods, including conventional methods, electrospinning, three-dimensional printing, and a combination of molding techniques. Furthermore, the differences among the properties of tissues, such as pore size and distribution, porosity, structure, and mechanical properties, are elucidated and critically reviewed. Some studies that combine two or more methods are also reviewed. Finally, this paper provides some guidance and suggestions for the future of scaffold fabrication.

  1. Scaffolding in geometry based on self regulated learning

    Science.gov (United States)

    Bayuningsih, A. S.; Usodo, B.; Subanti, S.

    2017-12-01

    This research aim to know the influence of problem based learning model by scaffolding technique on junior high school student’s learning achievement. This research took location on the junior high school in Banyumas. The research data obtained through mathematic learning achievement test and self-regulated learning (SRL) questioner. Then, the data analysis used two ways ANOVA. The results showed that scaffolding has positive effect to the mathematic learning achievement. The mathematic learning achievement use PBL-Scaffolding model is better than use PBL. The high SRL category student has better mathematic learning achievement than middle and low SRL categories, and then the middle SRL category has better than low SRL category. So, there are interactions between learning model with self-regulated learning in increasing mathematic learning achievement.

  2. Soft chitosan microbeads scaffold for 3D functional neuronal networks.

    Science.gov (United States)

    Tedesco, Maria Teresa; Di Lisa, Donatella; Massobrio, Paolo; Colistra, Nicolò; Pesce, Mattia; Catelani, Tiziano; Dellacasa, Elena; Raiteri, Roberto; Martinoia, Sergio; Pastorino, Laura

    2018-02-01

    The availability of 3D biomimetic in vitro neuronal networks of mammalian neurons represents a pivotal step for the development of brain-on-a-chip experimental models to study neuronal (dys)functions and particularly neuronal connectivity. The use of hydrogel-based scaffolds for 3D cell cultures has been extensively studied in the last years. However, limited work on biomimetic 3D neuronal cultures has been carried out to date. In this respect, here we investigated the use of a widely popular polysaccharide, chitosan (CHI), for the fabrication of a microbead based 3D scaffold to be coupled to primary neuronal cells. CHI microbeads were characterized by optical and atomic force microscopies. The cell/scaffold interaction was deeply characterized by transmission electron microscopy and by immunocytochemistry using confocal microscopy. Finally, a preliminary electrophysiological characterization by micro-electrode arrays was carried out. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Tailored PVA/ECM Scaffolds for Cartilage Regeneration

    Directory of Open Access Journals (Sweden)

    Elena Stocco

    2014-01-01

    Full Text Available Articular cartilage lesions are a particular challenge for regenerative medicine due to cartilage low self-ability repair in case of damage. Hence, a significant goal of musculoskeletal tissue engineering is the development of suitable structures in virtue of their matrix composition and biomechanical properties. The objective of our study was to design in vitro a supporting structure for autologous chondrocyte growth. We realized a biohybrid composite scaffold combining a novel and nonspecific extracellular matrix (ECM, which is decellularized Wharton’s jelly ECM, with the biomechanical properties of the synthetic hydrogel polyvinyl alcohol (PVA. Wharton’s jelly ECM was tested for its ability in promoting scaffold colonization by chondrocytes and compared with polyvinyl alcohol itself and the more specific decellularized cartilage matrix. Our preliminary evidences highlighted the chance of using Wharton’s jelly ECM in combination with PVA hydrogels as an innovative and easily available scaffold for cartilage restoration.

  4. Efficient Computational Design of a Scaffold for Cartilage Cell Regeneration

    DEFF Research Database (Denmark)

    Tajsoleiman, Tannaz; Jafar Abdekhodaie, Mohammad; Gernaey, Krist V.

    2018-01-01

    Due to the sensitivity of mammalian cell cultures, understanding the influence of operating conditions during a tissue generation procedure is crucial. In this regard, a detailed study of scaffold based cell culture under a perfusion flow is presented with the aid of mathematical modelling...... and computational fluid dynamics (CFD). With respect to the complexity of the case study, this work focuses solely on the effect of nutrient and metabolite concentrations, and the possible influence of fluid-induced shear stress on a targeted cell (cartilage) culture. The simulation set up gives the possibility...... of predicting the cell culture behavior under various operating conditions and scaffold designs. Thereby, the exploitation of the predictive simulation into a newly developed stochastic routine provides the opportunity of exploring improved scaffold geometry designs. This approach was applied on a common type...

  5. Annealing free, clean graphene transfer using alternative polymer scaffolds

    International Nuclear Information System (INIS)

    Wood, Joshua D; Doidge, Gregory P; Carrion, Enrique A; Koepke, Justin C; Datye, Isha; Behnam, Ashkan; Hewaparakrama, Jayan; Aruin, Basil; Chen, Yaofeng; Lyding, Joseph W; Kaitz, Joshua A; Dong, Hefei; Haasch, Richard T; Pop, Eric

    2015-01-01

    We examine the transfer of graphene grown by chemical vapor deposition (CVD) with polymer scaffolds of poly(methyl methacrylate) (PMMA), poly(lactic acid) (PLA), poly(phthalaldehyde) (PPA), and poly(bisphenol A carbonate) (PC). We find that optimally reactive PC scaffolds provide the cleanest graphene transfers without any annealing, after extensive comparison with optical microscopy, x-ray photoelectron spectroscopy, atomic force microscopy, and scanning tunneling microscopy. Comparatively, films transferred with PLA, PPA, PMMA/PC, and PMMA have a two-fold higher roughness and a five-fold higher chemical doping. Using PC scaffolds, we demonstrate the clean transfer of CVD multilayer graphene, fluorinated graphene, and hexagonal boron nitride. Our annealing free, PC transfers enable the use of atomically-clean nanomaterials in biomolecule encapsulation and flexible electronic applications. (paper)

  6. Cognitive memory.

    Science.gov (United States)

    Widrow, Bernard; Aragon, Juan Carlos

    2013-05-01

    Regarding the workings of the human mind, memory and pattern recognition seem to be intertwined. You generally do not have one without the other. Taking inspiration from life experience, a new form of computer memory has been devised. Certain conjectures about human memory are keys to the central idea. The design of a practical and useful "cognitive" memory system is contemplated, a memory system that may also serve as a model for many aspects of human memory. The new memory does not function like a computer memory where specific data is stored in specific numbered registers and retrieval is done by reading the contents of the specified memory register, or done by matching key words as with a document search. Incoming sensory data would be stored at the next available empty memory location, and indeed could be stored redundantly at several empty locations. The stored sensory data would neither have key words nor would it be located in known or specified memory locations. Sensory inputs concerning a single object or subject are stored together as patterns in a single "file folder" or "memory folder". When the contents of the folder are retrieved, sights, sounds, tactile feel, smell, etc., are obtained all at the same time. Retrieval would be initiated by a query or a prompt signal from a current set of sensory inputs or patterns. A search through the memory would be made to locate stored data that correlates with or relates to the prompt input. The search would be done by a retrieval system whose first stage makes use of autoassociative artificial neural networks and whose second stage relies on exhaustive search. Applications of cognitive memory systems have been made to visual aircraft identification, aircraft navigation, and human facial recognition. Concerning human memory, reasons are given why it is unlikely that long-term memory is stored in the synapses of the brain's neural networks. Reasons are given suggesting that long-term memory is stored in DNA or RNA

  7. 3D-printed scaffolds based on PLA/HA nanocomposites for trabecular bone reconstruction

    International Nuclear Information System (INIS)

    Niaza, K V; Senatov, F S; Kaloshkin, S D; Maksimkin, A V; Chukov, D I

    2016-01-01

    In the present work porous PLA scaffolds filled with micro- and nano- HA were studied. Both composites with micro- and nano-HA were obtained by extrusion in the same conditions. Scaffolds were obtained by 3D-printing by fused filament fabrication method. Structure of porous scaffolds was pre-modeled by computer software. Compression and three - point flexural tests were used to study mechanical properties of the scaffolds. (paper)

  8. Mechanical and cytotoxicity evaluation of nanostructured hydroxyapatite-bredigite scaffolds for bone regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Eilbagi, Marjan; Emadi, Rahmatollah; Raeissi, Keyvan [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Kharaziha, Mahshid, E-mail: ma.kharaziha@gmail.com [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Valiani, Ali [Department of Anatomical Sciences, School of Medicine, Isfahan University of Medical Sciences, Isfahan 81746-73441 (Iran, Islamic Republic of)

    2016-11-01

    Despite the attractive characteristics of three-dimensional pure hydroxyapatite (HA) scaffolds, due to their weak mechanical properties, researches have focused on the development of composite scaffolds via introducing suitable secondary components. The aim of this study was to develop, for the first time, three-dimensional HA-bredigite (Ca{sub 7}MgSi{sub 4}O{sub 16}) scaffolds containing various amounts of bredigite nanopowder (0, 5, 10 and 15 wt.%) using space holder technique. Transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction spectroscopy were applied in order to study the morphology, fracture surface and phase compositions of nanopowders and scaffolds. Furthermore, the effects of scaffold composition on the mechanical properties, bioactivity, biodegradability, and cytotoxicity were also evaluated. Results showed that the composite scaffolds with average pore size in the range of 220–310 μm, appearance porosity of 63.1–75.9% and appearance density of 1.1 ± 0.04 g/cm{sup 3} were successfully developed, depending on bredigite content. Indeed, the micropore size of the scaffolds reduced with increasing bredigite content confirming that the sinterability of the scaffolds was improved. Furthermore, the compression strength and modulus of the scaffolds significantly enhanced via incorporation of bredigite content from 0 to 15 wt.%. The composite scaffolds revealed superior bioactivity and biodegradability with increasing bredigite content. Moreover, MTT assay confirmed that HA-15 wt.% bredigite scaffold significantly promoted cell proliferation compared to tissue culture plate (control) and HA scaffold. Based on these results, three-dimensional HA-bredigite scaffolds could be promising replacements for HA scaffolds in bone regeneration. - Highlights: • Nanostructured hydroxyapatite-bredigite composite scaffolds were developed using space holder technique. • Presence of bredigite

  9. Polymer-Ceramic Composite Scaffolds: The Effect of Hydroxyapatite and β-tri-Calcium Phosphate

    OpenAIRE

    Boyang Huang; Guilherme Caetano; Cian Vyas; Jonny James Blaker; Carl Diver; Paulo Bártolo

    2018-01-01

    The design of bioactive scaffolds with improved mechanical and biological properties is an important topic of research. This paper investigates the use of polymer-ceramic composite scaffolds for bone tissue engineering. Different ceramic materials (hydroxyapatite (HA) and β-tri-calcium phosphate (TCP)) were mixed with poly-ε-caprolactone (PCL). Scaffolds with different material compositions were produced using an extrusion-based additive manufacturing system. The produced scaffolds were physi...

  10. Rapid prototyping for tissue-engineered bone scaffold by 3D printing and biocompatibility study.

    Science.gov (United States)

    He, Hui-Yu; Zhang, Jia-Yu; Mi, Xue; Hu, Yang; Gu, Xiao-Yu

    2015-01-01

    The prototyping of tissue-engineered bone scaffold (calcined goat spongy bone-biphasic ceramic composite/PVA gel) by 3D printing was performed, and the biocompatibility of the fabricated bone scaffold was studied. Pre-designed STL file was imported into the GXYZ303010-XYLE 3D printing system, and the tissue-engineered bone scaffold was fabricated by 3D printing using gel extrusion. Rabbit bone marrow stromal cells (BMSCs) were cultured in vitro and then inoculated to the sterilized bone scaffold obtained by 3D printing. The growth of rabbit BMSCs on the bone scaffold was observed under the scanning electron microscope (SEM). The effect of the tissue-engineered bone scaffold on the proliferation and differentiation of rabbit BMSCs using MTT assay. Universal testing machine was adopted to test the tensile strength of the bone scaffold. The leachate of the bone scaffold was prepared and injected into the New Zealand rabbits. Cytotoxicity test, acute toxicity test, pyrogenic test and intracutaneous stimulation test were performed to assess the biocompatibility of the bone scaffold. Bone scaffold manufactured by 3D printing had uniform pore size with the porosity of about 68.3%. The pores were well interconnected, and the bone scaffold showed excellent mechanical property. Rabbit BMSCs grew and proliferated on the surface of the bone scaffold after adherence. MTT assay indicated that the proliferation and differentiation of rabbit BMSCs on the bone scaffold did not differ significantly from that of the cells in the control. In vivo experiments proved that the bone scaffold fabricated by 3D printing had no acute toxicity, pyrogenic reaction or stimulation. Bone scaffold manufactured by 3D printing allows the rabbit BMSCs to adhere, grow and proliferate and exhibits excellent biomechanical property and high biocompatibility. 3D printing has a good application prospect in the prototyping of tissue-engineered bone scaffold.

  11. 3D-printed scaffolds based on PLA/HA nanocomposites for trabecular bone reconstruction

    Science.gov (United States)

    Niaza, K. V.; Senatov, F. S.; Kaloshkin, S. D.; Maksimkin, A. V.; Chukov, D. I.

    2016-08-01

    In the present work porous PLA scaffolds filled with micro- and nano- HA were studied. Both composites with micro- and nano-HA were obtained by extrusion in the same conditions. Scaffolds were obtained by 3D-printing by fused filament fabrication method. Structure of porous scaffolds was pre-modeled by computer software. Compression and three - point flexural tests were used to study mechanical properties of the scaffolds.

  12. Relationship between micro-porosity, water permeability and mechanical behavior in scaffolds for cartilage engineering.

    Science.gov (United States)

    Vikingsson, L; Claessens, B; Gómez-Tejedor, J A; Gallego Ferrer, G; Gómez Ribelles, J L

    2015-08-01

    In tissue engineering the design and optimization of biodegradable polymeric scaffolds with a 3D-structure is an important field. The porous scaffold provide the cells with an adequate biomechanical environment that allows mechanotransduction signals for cell differentiation and the scaffolds also protect the cells from initial compressive loading. The scaffold have interconnected macro-pores that host the cells and newly formed tissue, while the pore walls should be micro-porous to transport nutrients and waste products. Polycaprolactone (PCL) scaffolds with a double micro- and macro-pore architecture have been proposed for cartilage regeneration. This work explores the influence of the micro-porosity of the pore walls on water permeability and scaffold compliance. A Poly(Vinyl Alcohol) with tailored mechanical properties has been used to simulate the growing cartilage tissue inside the scaffold pores. Unconfined and confined compression tests were performed to characterize both the water permeability and the mechanical response of scaffolds with varying size of micro-porosity while volume fraction of the macro-pores remains constant. The stress relaxation tests show that the stress response of the scaffold/hydrogel construct is a synergic effect determined by the performance of the both components. This is interesting since it suggests that the in vivo outcome of the scaffold is not only dependent upon the material architecture but also the growing tissue inside the scaffold׳s pores. On the other hand, confined compression results show that compliance of the scaffold is mainly controlled by the micro-porosity of the scaffold and less by hydrogel density in the scaffold pores. These conclusions bring together valuable information for customizing the optimal scaffold and to predict the in vivo mechanical behavior. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Comparison of glutaraldehyde and carbodiimides to crosslink tissue engineering scaffolds fabricated by decellularized porcine menisci

    International Nuclear Information System (INIS)

    Gao, Shuang; Yuan, Zhiguo; Guo, Weimin; Chen, Mingxue; Liu, Shuyun; Xi, Tingfei; Guo, Quanyi

    2017-01-01

    The objectives of this study were to fabricate porous scaffolds using decellularized meniscus, and to explore a preferable crosslinking condition to enhance mechanical properties of scaffolds. Moreover, the microstructure, porosity, biodegradation and cytotoxicity were also evaluated. EDAC or GTA in different concentration was used to crosslink scaffolds. FTIR demonstrated functional groups change in crosslinking process. SEM photography showed that crosslinked scaffolds had blurry edges, which resulted scaffolds crosslinked by 1.2 mol/l EDAC had smaller porosity than other groups. The structure change enhanced antidegradation property. After immersing in enzyme solution for 96 h, scaffolds crosslinked by GTA and EDAC could maintain their mass > 70% and 80%. Most importantly, mechanical properties of crosslinked scaffolds were also improved. Uncrosslinked Scaffolds had only 0.49 kPa in compression modulus and 12.81 kPa in tensile modulus. The compression and tensile modulus of scaffolds crosslinked by 1.0% GTA were 1.42 and 567.44 kPa respectively. The same value of scaffolds crosslinked by 1.2 mol/l EDAC were 1.49 and 532.50 kPa. Scaffolds crosslinked by 1.0% and 2.5% GTA were toxic to cells, while EDAC groups showed no cytotoxicity. Chondrocytes could proliferate and infiltrate within scaffolds after seeding. Overall, 1.2 mol/l EDAC was a preferable crosslinking condition. - Highlights: • Porous meniscus scaffolds were fabricated using decellularized meniscus tissue. • Mechanical properties of meniscus scaffolds were enhanced by chemical crosslinking. • The crosslinked scaffold showed enhanced anti-degradation properties. • Chondrocytes could infiltrate and proliferate within crosslinked scaffolds.

  14. Comparison of glutaraldehyde and carbodiimides to crosslink tissue engineering scaffolds fabricated by decellularized porcine menisci

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Shuang [Center for Biomedical Material and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Yuan, Zhiguo; Guo, Weimin; Chen, Mingxue; Liu, Shuyun [Beijing Key Lab of Regenerative Medicine in Orthopaedics, Institute of Orthopaedics, Chinese PLA General Hospital, Beijing 100853 (China); Key Laboratory of Musculoskeletal Trauma & War Injuries, Institute of Orthopaedics, Chinese PLA General Hospital, Beijing 100853 (China); Xi, Tingfei, E-mail: tingfeixi@163.com [Center for Biomedical Material and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Shenzhen Institute, Peking University, Shenzhen 518057 (China); Guo, Quanyi, E-mail: doctorguo_301@163.com [Beijing Key Lab of Regenerative Medicine in Orthopaedics, Institute of Orthopaedics, Chinese PLA General Hospital, Beijing 100853 (China); Key Laboratory of Musculoskeletal Trauma & War Injuries, Institute of Orthopaedics, Chinese PLA General Hospital, Beijing 100853 (China)

    2017-02-01

    The objectives of this study were to fabricate porous scaffolds using decellularized meniscus, and to explore a preferable crosslinking condition to enhance mechanical properties of scaffolds. Moreover, the microstructure, porosity, biodegradation and cytotoxicity were also evaluated. EDAC or GTA in different concentration was used to crosslink scaffolds. FTIR demonstrated functional groups change in crosslinking process. SEM photography showed that crosslinked scaffolds had blurry edges, which resulted scaffolds crosslinked by 1.2 mol/l EDAC had smaller porosity than other groups. The structure change enhanced antidegradation property. After immersing in enzyme solution for 96 h, scaffolds crosslinked by GTA and EDAC could maintain their mass > 70% and 80%. Most importantly, mechanical properties of crosslinked scaffolds were also improved. Uncrosslinked Scaffolds had only 0.49 kPa in compression modulus and 12.81 kPa in tensile modulus. The compression and tensile modulus of scaffolds crosslinked by 1.0% GTA were 1.42 and 567.44 kPa respectively. The same value of scaffolds crosslinked by 1.2 mol/l EDAC were 1.49 and 532.50 kPa. Scaffolds crosslinked by 1.0% and 2.5% GTA were toxic to cells, while EDAC groups showed no cytotoxicity. Chondrocytes could proliferate and infiltrate within scaffolds after seeding. Overall, 1.2 mol/l EDAC was a preferable crosslinking condition. - Highlights: • Porous meniscus scaffolds were fabricated using decellularized meniscus tissue. • Mechanical properties of meniscus scaffolds were enhanced by chemical crosslinking. • The crosslinked scaffold showed enhanced anti-degradation properties. • Chondrocytes could infiltrate and proliferate within crosslinked scaffolds.

  15. Decellularized Human Dental Pulp as a Scaffold for Regenerative Endodontics.

    Science.gov (United States)

    Song, J S; Takimoto, K; Jeon, M; Vadakekalam, J; Ruparel, N B; Diogenes, A

    2017-06-01

    Teeth undergo postnatal organogenesis relatively late in life and only complete full maturation a few years after the crown first erupts in the oral cavity. At this stage, development can be arrested if the tooth organ is damaged by either trauma or caries. Regenerative endodontic procedures (REPs) are a treatment alternative to conventional root canal treatment for immature teeth. These procedures rely on the transfer of apically positioned stem cells, including stem cells of the apical papilla (SCAP), into the root canal system. Although clinical success has been reported for these procedures, the predictability of expected outcomes and the organization of the newly formed tissues are affected by the lack of an available suitable scaffold that mimics the complexity of the dental pulp extracellular matrix (ECM). In this study, we evaluated 3 methods of decellularization of human dental pulp to be used as a potential autograft scaffold. Tooth slices of human healthy extracted third molars were decellularized by 3 different methods. One of the methods generated the maximum observed decellularization with minimal impact on the ECM composition and organization. Furthermore, recellularization of the scaffold supported the proliferation of SCAP throughout the scaffold with differentiation into odontoblast-like cells near the dentinal walls. Thus, this study reports that human dental pulp from healthy extracted teeth can be successfully decellularized, and the resulting scaffold supports the proliferation and differentiation of SCAP. The future application of this form of an autograft in REPs can fulfill a yet unmet need for a suitable scaffold, potentially improving clinical outcomes and ultimately promoting the survival and function of teeth with otherwise poor prognosis.

  16. Analogical scaffolding: Making meaning in physics through representation and analogy

    Science.gov (United States)

    Podolefsky, Noah Solomon

    This work reviews the literature on analogy, introduces a new model of analogy, and presents a series of experiments that test and confirm the utility of this model to describe and predict student learning in physics with analogy. Pilot studies demonstrate that representations (e.g., diagrams) can play a key role in students' use of analogy. A new model of analogy, Analogical Scaffolding, is developed to explain these initial empirical results. This model will be described in detail, and then applied to describe and predict the outcomes of further experiments. Two large-scale (N>100) studies will demonstrate that: (1) students taught with analogies, according to the Analogical Scaffolding model, outperform students taught without analogies on pre-post assessments focused on electromagnetic waves; (2) the representational forms used to teach with analogy can play a significant role in student learning, with students in one treatment group outperforming students in other treatment groups by factors of two or three. It will be demonstrated that Analogical Scaffolding can be used to predict these results, as well as finer-grained results such as the types of distracters students choose in different treatment groups, and to describe and analyze student reasoning in interviews. Abstraction in physics is reconsidered using Analogical Scaffolding. An operational definition of abstraction is developed within the Analogical Scaffolding framework and employed to explain (a) why physicists consider some ideas more abstract than others in physics, and (b) how students conceptions of these ideas can be modeled. This new approach to abstraction suggests novel approaches to curriculum design in physics using Analogical Scaffolding.

  17. Engineering bone grafts with enhanced bone marrow and native scaffolds.

    Science.gov (United States)

    Hung, Ben P; Salter, Erin K; Temple, Josh; Mundinger, Gerhard S; Brown, Emile N; Brazio, Philip; Rodriguez, Eduardo D; Grayson, Warren L

    2013-01-01

    The translation of tissue engineering approaches to the clinic has been hampered by the inability to find suitable multipotent cell sources requiring minimal in vitro expansion. Enhanced bone marrow (eBM), which is obtained by reaming long bone medullary canals and isolating the solid marrow putty, has large quantities of stem cells and demonstrates significant potential to regenerate bone tissues. eBM, however, cannot impart immediate load-bearing mechanical integrity or maintain the gross anatomical structure to guide bone healing. Yet, its putty-like consistency creates a challenge for obtaining the uniform seeding necessary to effectively combine it with porous scaffolds. In this study, we examined the potential for combining eBM with mechanically strong, osteoinductive trabecular bone scaffolds for bone regeneration by creating channels into scaffolds for seeding the eBM. eBM was extracted from the femurs of adult Yorkshire pigs using a Synthes reamer-irrigator-aspirator device, analyzed histologically, and digested to extract cells and characterize their differentiation potential. To evaluate bone tissue formation, eBM was seeded into the channels in collagen-coated or noncoated scaffolds, cultured in osteogenic conditions for 4 weeks, harvested and assessed for tissue distribution and bone formation. Our data demonstrates that eBM is a heterogenous tissue containing multipotent cell populations. Furthermore, coating scaffolds with a collagen hydrogel significantly enhanced cellular migration, promoted uniform tissue development and increased bone mineral deposition. These findings suggest the potential for generating customized autologous bone grafts for treating critical-sized bone defects by combining a readily available eBM cell source with decellularized trabecular bone scaffolds. © 2013 S. Karger AG, Basel

  18. Scaffolds for Tendon and Ligament Repair and Regeneration

    Science.gov (United States)

    Ratcliffe, Anthony; Butler, David L; Dyment, Nathaniel A; Cagle, Paul J; Proctor, Christopher S; Ratcliffe, Seena S; Flatow, Evan L

    2015-01-01

    Enhanced tendon and ligament repair would have a major impact on orthopaedic surgery outcomes, resulting in reduced repair failures and repeat surgeries, more rapid return to function, and reduced health care costs. Scaffolds have been used for mechanical and biologic reinforcement of repair and regeneration with mixed results. This review summarizes efforts made using biologic and synthetic scaffolds using rotator cuff and ACL as examples of clinical applications, discusses recent advances that have shown promising clinical outcomes, and provides insight into future therapy. PMID:25650098

  19. Modern materials in fabrication of scaffolds for bone defect replacement

    Science.gov (United States)

    Bazlov, V. A.; Mamuladze, T. Z.; Pavlov, V. V.; Kirilova, I. A.; Sadovoy, M. A.

    2016-08-01

    The article defines the requirements for modern scaffold-forming materials and describes the main advantages and disadvantages of various synthetic materials. Osseointegration of synthetic scaffolds approved for use in medical practice is evaluated. Nylon 618 (certification ISO9001 1093-1-2009) is described as the most promising synthetic material used in medical practice. The authors briefly highlight the issues of individual bone grafting with the use of 3D printing technology. An example of contouring pelvis defect after removal of a giant tumor with the use of 3D models is provided.

  20. Semiotic scaffolding of the social self in reflexivity and friendship

    DEFF Research Database (Denmark)

    Emmeche, Claus

    2015-01-01

    scaffolding is a multi-level phenomenon. Focusing upon levels of semiosis specific to humans, the formation of the personal self and the role of friendship and similar interpersonal relations in this process is explored through Aristotle’s classical idea of the friend as ‘another self’, and sociologist...... Margaret Archer’s empirical and theoretical work on the interplay between individual subjectivity, social structure and interpersonal relations in a dynamics of human agency. It is shown that although processes of reflexivity and friendship can indeed be seen as instances of semiotic scaffolding...

  1. MODEL SCAFFOLDING PEMBELAJARAN MENULIS DENGAN PENDEKATAN PROSES BAGI ANAK TUNARUNGU

    Directory of Open Access Journals (Sweden)

    Yuliyati Endang Purbaningrum Endang Purbaningrum

    2016-10-01

    Full Text Available The aim for this researach is (1 to describe the needs analysis and challenges and (2 to produce the scaffolding draft model in learning writing using process ap-proach combined with the reflective maternal method (MMR. This research develop-ment applies R2D2 model which emphasizes users’ need based on the context (teacher-student with difable  and developed collaboratively. Based on the needs analysis in the field in the first year, scaffolding draft model was produced using approach elaborated with the reflective maternal method (MMR.

  2. Graphene foam as a biocompatible scaffold for culturing human neurons

    Science.gov (United States)

    Mattei, Cristiana; Nasr, Babak; Hudson, Emma J.; Alshawaf, Abdullah J.; Chana, Gursharan; Everall, Ian P.; Dottori, Mirella; Skafidas, Efstratios

    2018-01-01

    In this study, we explore the use of electrically active graphene foam as a scaffold for the culture of human-derived neurons. Human embryonic stem cell (hESC)-derived cortical neurons fated as either glutamatergic or GABAergic neuronal phenotypes were cultured on graphene foam. We show that graphene foam is biocompatible for the culture of human neurons, capable of supporting cell viability and differentiation of hESC-derived cortical neurons. Based on the findings, we propose that graphene foam represents a suitable scaffold for engineering neuronal tissue and warrants further investigation as a model for understanding neuronal maturation, function and circuit formation. PMID:29657752

  3. Scanning probe recognition microscopy investigation of tissue scaffold properties

    Science.gov (United States)

    Fan, Yuan; Chen, Qian; Ayres, Virginia M; Baczewski, Andrew D; Udpa, Lalita; Kumar, Shiva

    2007-01-01

    Scanning probe recognition microscopy is a new scanning probe microscopy technique which enables selective scanning along individual nanofibers within a tissue scaffold. Statistically significant data for multiple properties can be collected by repetitively fine-scanning an identical region of interest. The results of a scanning probe recognition microscopy investigation of the surface roughness and elasticity of a series of tissue scaffolds are presented. Deconvolution and statistical methods were developed and used for data accuracy along curved nanofiber surfaces. Nanofiber features were also independently analyzed using transmission electron microscopy, with results that supported the scanning probe recognition microscopy-based analysis. PMID:18203431

  4. The Effect of Various Media Scaffolding on Increasing Understanding of Students' Geometry Concepts

    Science.gov (United States)

    Sutiarso, Sugeng; Coesamin, M.; Nurhanurawati

    2018-01-01

    This study is a quasi-experimental research with pretest-posttest control group design, which aims to determine (1) the tendency of students in using various media scaffolding based on gender, and (2) effect of media scaffolding on increasing understanding of students' geometry concepts. Media scaffolding used this study is chart, props, and…

  5. Embroidered polymer-collagen hybrid scaffold variants for ligament tissue engineering.

    Science.gov (United States)

    Hoyer, M; Drechsel, N; Meyer, M; Meier, C; Hinüber, C; Breier, A; Hahner, J; Heinrich, G; Rentsch, C; Garbe, L-A; Ertel, W; Schulze-Tanzil, G; Lohan, A

    2014-10-01

    Embroidery techniques and patterns used for scaffold production allow the adaption of biomechanical scaffold properties. The integration of collagen into embroidered polylactide-co-caprolactone [P(LA-CL)] and polydioxanone (PDS) scaffolds could stimulate neo-tissue formation by anterior cruciate ligament (ACL) cells. Therefore, the aim of this study was to test embroidered P(LA-CL) and PDS scaffolds as hybrid scaffolds in combination with collagen hydrogel, sponge or foam for ligament tissue engineering. ACL cells were cultured on embroidered P(LA-CL) and PDS scaffolds without or with collagen supplementation. Cell adherence, vitality, morphology and ECM synthesis were analyzed. Irrespective of thread size, ACL cells seeded on P(LA-CL) scaffolds without collagen adhered and spread over the threads, whereas the cells formed clusters on PDS and larger areas remained cell-free. Using the collagen hydrogel, the scaffold colonization was limited by the gel instability. The collagen sponge layers integrated into the scaffolds were hardly penetrated by the cells. Collagen foams increased scaffold colonization in P(LA-CL) but did not facilitate direct cell-thread contacts in the PDS scaffolds. The results suggest embroidered P(LA-CL) scaffolds as a more promising basis for tissue engineering an ACL substitute than PDS due to superior cell attachment. Supplementation with a collagen foam presents a promising functionalization strategy. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Online Process Scaffolding and Students' Self-Regulated Learning with Hypermedia.

    Science.gov (United States)

    Azevedo, Roger; Cromley, Jennifer G.; Thomas, Leslie; Seibert, Diane; Tron, Myriam

    This study examined the role of different scaffolding instructional interventions in facilitating students' shift to more sophisticated mental models as indicated by both performance and process data. Undergraduate students (n=53) were randomly assigned to 1 of 3 scaffolding conditions (adaptive content and process scaffolding (ACPS), adaptive…

  7. Impedance Spectroscopic Characterisation of Porosity in 3D Cell Culture Scaffolds with Different Channel Networks

    DEFF Research Database (Denmark)

    Canali, Chiara; Mohanty, Soumyaranjan; Heiskanen, Arto

    2015-01-01

    We present the application of electrochemical impedance spectroscopy (EIS) as a method for discriminating between different polydimethylsiloxane (PDMS) scaffolds for three-dimensional (3D) cell cultures. The validity of EIS characterisation for scaffolds having different degree of porosity...... serve as means of single-frequency measurements for fast scaffold characterization combined with in vitro monitoring of 3D cell cultures....

  8. 29 CFR 1926.452 - Additional requirements applicable to specific types of scaffolds.

    Science.gov (United States)

    2010-07-01

    .... (h) Roof bracket scaffolds. (1) Scaffold brackets shall be constructed to fit the pitch of the roof... metal plates and angles. Each pump jack bracket shall have two positive gripping mechanisms to prevent... ensure that it will not chafe at any point where a change in direction occurs, and (iv) The scaffold is...

  9. Directed Self-Inquiry: A Scaffold for Teaching Laboratory Report Writing

    Science.gov (United States)

    Deiner, L. Jay; Newsome, Daniel; Samaroo, Diana

    2012-01-01

    A scaffold was created for the explicit instruction of laboratory report writing. The scaffold breaks the laboratory report into sections and teaches students to ask and answer questions in order to generate section-appropriate content and language. Implementation of the scaffold is done through a series of section-specific worksheets that are…

  10. Dynamic Scaffolding of Socially Regulated Learning in a Computer-Based Learning Environment

    NARCIS (Netherlands)

    Molenaar, I.; Roda, Claudia; van Boxtel, Carla A.M.; Sleegers, P.J.C.

    2012-01-01

    The aim of this study is to test the effects of dynamically scaffolding social regulation of middle school students working in a computer-based learning environment. Dyads in the scaffolding condition (N = 56) are supported with computer-generated scaffolds and students in the control condition (N =

  11. Preparation and biocompatibility evaluation of apatite/wollastonite-derived porous bioactive glass ceramic scaffolds

    International Nuclear Information System (INIS)

    Zhang Hua; Ye Xiaojian; Li Jiashun

    2009-01-01

    An apatite/wollastonite-derived (A/W) porous glass ceramic scaffold with highly interconnected pores was successfully fabricated by adding a plastic porosifier. The morphology, porosity and mechanical strength were characterized. The results showed that the glass ceramic scaffold with controllable pore size and porosity displayed open macropores. In addition, good in vitro bioactivity was found for the scaffold obtained by soaking it in simulated body fluid. Mesenchymal stem cells (MSCs) were cultured, expanded and seeded on the scaffold, and the adhesion and proliferation of MSCs were determined using MTT assay and environmental scanning electron microscopy (ESEM). The results revealed that the scaffold was biocompatible and had no negative effects on the MSCs in vitro. The in vivo biocompatibility and osteogenicity were investigated by implanting both the pure scaffold and the MSC/scaffold construct in rabbit mandibles and studying histologically. The results showed that the glass ceramic scaffold exhibited good biocompatibility and osteoconductivity. Moreover, the introduction of MSCs into the scaffold observably improved the efficiency of new bone formation, especially at the initial stage after implantation. However, the glass ceramic scaffold showed the same good biocompatibility and osteogenicity as the hybrid one at the later stage. These results indicate that porous bioactive scaffolds based on the original apatite-wollastonite glass ceramic fulfil the basic requirements of a bone tissue engineering scaffold.

  12. Surface modification of polycaprolactone scaffolds fabricated via selective laser sintering for cartilage tissue engineering

    International Nuclear Information System (INIS)

    Chen, Chih-Hao; Lee, Ming-Yih; Shyu, Victor Bong-Hang; Chen, Yi-Chieh; Chen, Chien-Tzung; Chen, Jyh-Ping

    2014-01-01

    Surface modified porous polycaprolactone scaffolds fabricated via rapid prototyping techniques were evaluated for cartilage tissue engineering purposes. Polycaprolactone scaffolds manufactured by selective laser sintering (SLS) were surface modified through immersion coating with either gelatin or collagen. Three groups of scaffolds were created and compared for both mechanical and biological properties. Surface modification with collagen or gelatin improved the hydrophilicity, water uptake and mechanical strength of the pristine scaffold. From microscopic observations and biochemical analysis, collagen-modified scaffold was the best for cartilage tissue engineering in terms of cell proliferation and extracellular matrix production. Chondrocytes/collagen-modified scaffold constructs were implanted subdermally in the dorsal spaces of female nude mice. Histological and immunohistochemical staining of the retrieved implants after 8 weeks revealed enhanced cartilage tissue formation. We conclude that collagen surface modification through immersion coating on SLS-manufactured scaffolds is a feasible scaffold for cartilage tissue engineering in craniofacial reconstruction. - Highlights: • Selective laser sintered polycaprolactone scaffolds are prepared. • Scaffolds are surface modified through immersion coating with gelatin or collagen. • Collagen-scaffold is the best for cartilage tissue engineering in vitro. • Chondrocytes/collagen-scaffold reveals enhanced cartilage tissue formation in vivo

  13. Designing and Implementing Web-Based Scaffolding Tools for Technology-Enhanced Socioscientific Inquiry

    Science.gov (United States)

    Shin, Suhkyung; Brush, Thomas A.; Glazewski, Krista D.

    2017-01-01

    This study explores how web-based scaffolding tools provide instructional support while implementing a socio-scientific inquiry (SSI) unit in a science classroom. This case study focused on how students used web-based scaffolding tools during SSI activities, and how students perceived the SSI unit and the scaffolding tools embedded in the SSI…

  14. Fabrication and characterization of strontium incorporated 3-D bioactive glass scaffolds for bone tissue from biosilica

    Energy Technology Data Exchange (ETDEWEB)

    Özarslan, Ali Can, E-mail: alicanozarslan@gmail.com; Yücel, Sevil, E-mail: syucel@yildiz.edu.tr

    2016-11-01

    Bioactive glass scaffolds that contain silica are high viable biomaterials as bone supporters for bone tissue engineering due to their bioactive behaviour in simulated body fluid (SBF). In the human body, these materials help inorganic bone structure formation due to a combination of the particular ratio of elements such as silicon (Si), calcium (Ca), sodium (Na) and phosphorus (P), and the doping of strontium (Sr) into the scaffold structure increases their bioactive behaviour. In this study, bioactive glass scaffolds were produced by using rice hull ash (RHA) silica and commercial silica based bioactive glasses. The structural properties of scaffolds such as pore size, porosity and also the bioactive behaviour were investigated. The results showed that undoped and Sr-doped RHA silica-based bioactive glass scaffolds have better bioactivity than that of commercial silica based bioactive glass scaffolds. Moreover, undoped and Sr-doped RHA silica-based bioactive glass scaffolds will be able to be used instead of undoped and Sr-doped commercial silica based bioactive glass scaffolds for bone regeneration applications. Scaffolds that are produced from undoped or Sr-doped RHA silica have high potential to form new bone for bone defects in tissue engineering. - Highlights: • Production of 3-D bioactive glass scaffolds from different silica sources • The effect of biosilica from rice hull ash on the bioactive glass scaffold • Sr additive impact on the bioactivity and biodegradability properties of scaffolds.

  15. Surface modification of polycaprolactone scaffolds fabricated via selective laser sintering for cartilage tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chih-Hao [Department of Chemical and Materials Engineering, Chang Gung University, Kweishan, Taoyuan 333, Taiwan, ROC (China); Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Craniofacial Research Center, Chang Gung University, Kweishann, Taoyuan 333, Taiwan, ROC (China); Lee, Ming-Yih [Graduate Institute of Medical Mechatronics, Chang Gung University, Kweishan, Taoyuan 333, Taiwan, ROC (China); Shyu, Victor Bong-Hang; Chen, Yi-Chieh; Chen, Chien-Tzung [Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Craniofacial Research Center, Chang Gung University, Kweishann, Taoyuan 333, Taiwan, ROC (China); Chen, Jyh-Ping, E-mail: jpchen@mail.cgu.edu.tw [Department of Chemical and Materials Engineering, Chang Gung University, Kweishan, Taoyuan 333, Taiwan, ROC (China); Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Kweishan, Taoyuan 333, Taiwan, ROC (China)

    2014-07-01

    Surface modified porous polycaprolactone scaffolds fabricated via rapid prototyping techniques were evaluated for cartilage tissue engineering purposes. Polycaprolactone scaffolds manufactured by selective laser sintering (SLS) were surface modified through immersion coating with either gelatin or collagen. Three groups of scaffolds were created and compared for both mechanical and biological properties. Surface modification with collagen or gelatin improved the hydrophilicity, water uptake and mechanical strength of the pristine scaffold. From microscopic observations and biochemical analysis, collagen-modified scaffold was the best for cartilage tissue engineering in terms of cell proliferation and extracellular matrix production. Chondrocytes/collagen-modified scaffold constructs were implanted subdermally in the dorsal spaces of female nude mice. Histological and immunohistochemical staining of the retrieved implants after 8 weeks revealed enhanced cartilage tissue formation. We conclude that collagen surface modification through immersion coating on SLS-manufactured scaffolds is a feasible scaffold for cartilage tissue engineering in craniofacial reconstruction. - Highlights: • Selective laser sintered polycaprolactone scaffolds are prepared. • Scaffolds are surface modified through immersion coating with gelatin or collagen. • Collagen-scaffold is the best for cartilage tissue engineering in vitro. • Chondrocytes/collagen-scaffold reveals enhanced cartilage tissue formation in vivo.

  16. Conductive vancomycin-loaded mesoporous silica polypyrrole-based scaffolds for bone regeneration

    DEFF Research Database (Denmark)

    Zanjanizadeh Ezazi, Nazanin; Shahbazi, Mohammad-Ali; Shatalin, Yuri V.

    2018-01-01

    -conductive scaffolds. Osteoblast cells were perfectly immersed into the gelatin matrix and remained viable for 14 days. Overall, new conductive composite bone scaffolds were created and the obtained results strongly verified the applicability of this conductive scaffold in drug delivery, encouraging its further...

  17. Explanatory factors for first and second-generation non-western women's inadequate prenatal care utilisation: a prospective cohort study.

    Science.gov (United States)

    Boerleider, Agatha W; Manniën, Judith; van Stenus, Cherelle M V; Wiegers, Therese A; Feijen-de Jong, Esther I; Spelten, Evelien R; Devillé, Walter L J M

    2015-04-21

    Little research into non-western women's prenatal care utilisation in industrialised western countries has taken generational differences into account. In this study we examined non-western women's prenatal care utilisation and its explanatory factors according to generational status. Data from 3300 women participating in a prospective cohort of primary midwifery care clients (i.e. women with no complications or no increased risk for complications during pregnancy, childbirth and the puerperium who receive maternity care by autonomous midwives) in the Netherlands (the DELIVER study) was used. Gestational age at entry and the total number of prenatal visits were aggregated into an index. The extent to which potential factors explained non-western women's prenatal care utilisation was assessed by means of blockwise logistic regression analyses and percentage changes in odds ratios. The unadjusted odds of first and second-generation non-western women making inadequate use of prenatal care were 3.26 and 1.96 times greater than for native Dutch women. For the first generation, sociocultural factors explained 43% of inadequate prenatal care utilisation, socioeconomic factors explained 33% and demographic and pregnancy factors explained 29%. For the second generation, sociocultural factors explained 66% of inadequate prenatal care utilisation. Irrespective of generation, strategies to improve utilisation should focus on those with the following sociocultural characteristics (not speaking Dutch at home, no partner or a first-generation non-Dutch partner). For the first generation, strategies should also focus on those with the following demographic, pregnancy and socioeconomic characteristics (aged ≤ 19 or ≥ 36, unplanned pregnancies, poor obstetric histories (extra-uterine pregnancy, molar pregnancy or abortion), a low educational level, below average net household income and no supplementary insurance.

  18. Inadequate Riboflavin Intake and Anemia Risk in a Chinese Population: Five-Year Follow Up of the Jiangsu Nutrition Study

    Science.gov (United States)

    Shi, Zumin; Zhen, Shiqi; Wittert, Gary A.; Yuan, Baojun; Zuo, Hui; Taylor, Anne W.

    2014-01-01

    Objectives Riboflavin (vitamin B2) has been shown in animal studies to affect the absorption and metabolism of iron. Cross-sectional population studies show a relationship between riboflavin intake and anemia but prospective population studies are limited. The aim of the study was to determine the relationship between riboflavin intake and the risk of anemia in a Chinese cohort. Method The study used data from 1253 Chinese men and women who participated in two waves of the Jiangsu Nutrition Study (JIN), five years apart, in 2002 and 2007. Riboflavin intake and hemoglobin (Hb) were quantitatively assessed together with dietary patterns, lifestyle, socio-demographic and health-related factors. Results At baseline, 97.2% of participants had inadequate riboflavin intake (below the estimate average requirement). Riboflavin intake was positively associated with anemia at baseline, but low riboflavin intake was associated with an increased risk of anemia at follow-up among those anemic at baseline. In the multivariate model, adjusting for demographic and lifestyle factors and dietary patterns, the relative risk and 95% confidence interval for anemia at follow-up, across quartiles of riboflavin intake were: 1, 0.82(0.54–1.23), 0.56(0.34–0.93), 0.52(0.28–0.98) (p for trend 0.021). There was a significant interaction between riboflavin and iron intake; when riboflavin intake was low, a high iron intake was associated with a lower probability of anemia at follow-up. This association disappeared when riboflavin intake was high. Conclusion Inadequate riboflavin intake is common and increases the risk of anemia in Chinese adults. Given the interaction with iron intake correcting inadequate riboflavin intake may be a priority in the prevention of anemia, and population based measurement and intervention trials are required. PMID:24533156

  19. Inadequate functional health literacy in Spanish as a barrier to cervical cancer screening among immigrant Latinas in New York City.

    Science.gov (United States)

    Garbers, Samantha; Chiasson, Mary Ann

    2004-10-01

    The objective of this study was to examine the association between inadequate functional health literacy in Spanish among low-income Latinas aged 40 and older and cervical cancer screening knowledge and behavior. Spanish-speaking Latinas aged 40-78 of various nationalities (n = 205) participated in a study that included a survey on cervical cancer knowledge and behavior administered in Spanish and the Spanish version of the Test of Functional Health Literacy in Adults. Compared to those with adequate and marginal health literacy, women with inadequate functional health literacy in Spanish were significantly less likely to have ever had a Papanicolaou (Pap) test (odds ratio, 0.12; 95% confidence interval [CI], 0.04-0.37) or in the last three years (odds ratio, 0.35; 95% CI, 0.18-0.68) and were significantly more likely to have had their last Pap test at a local public hospital (odds ratio, 2.43; 95% CI, 1.18-4.97). Even when controlling for other factors, women with inadequate health literacy were 16.7 times less likely (adjusted odds ratio, 0.06; 95% CI, 0.01-0.55) to have ever had a Pap test. Almost half of the population we studied will have difficulty interpreting written medical materials, even in Spanish. When developing efforts to reach women who have not been screened, programs and service providers need to be aware that the women most in need of information about screening may be more likely to be unable to read any written materials provided to them, regardless of the language or level of simplicity of the materials. Programs and strategies need to be implemented to increase screening prevalence and to minimize the identified gaps in regular screening for Latinas who have low health literacy.

  20. Social cognitive correlates of young adult sport competitors' sunscreen use.

    Science.gov (United States)

    Berndt, Nadine C; O'Riordan, David L; Winkler, Elisabeth; McDermott, Liane; Spathonis, Kym; Owen, Neville

    2011-02-01

    Young adults participating in outdoor sports represent a high-risk group for excessive sun exposure. The purpose of this study was to identify modifiable social cognitive correlates of sunscreen use among young adult competitors. Participants aged 18 to 30 years who competed in soccer (n = 65), surf-lifesaving (n = 63), hockey (n = 61), and tennis (n = 48) completed a sun habits survey. Almost half (n = 113) of the participants used sunscreen inadequately and 30% (n = 70) reported not using sunscreen. In fully adjusted models, social cognitive attributes significantly (p competitors and as a result may be useful in informing behavior change interventions within the sporting context.