Photocatalysis of Modified Transition Metal Oxide Surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batzill, Matthias

The goal of this project has been to establish a cause-effect relationship for photocatalytic activity variations of different structures of the same material; and furthermore gain fundamental understanding on modification of photocatalysts by compositional or surface modifications. The reasoning is that gaining atomic scale understanding of how surface and bulk modifications alter the photo reactivity will lead to design principles for next generation photocatalysts. As a prototypical photocatalyst the research focused on TiO 2 synthesized in well-defined single crystalline form to enable fundamental characterizations.We have obtained results in the following areas: (a) Preparation of epitaxial anatase TiO 2 samples bymore » pulsed laser deposition. (b) Comparison of hydrogen diffusion on different crystallographic surface. (c) Determining the stability of the TiO 2(011)-2x1 reconstruction upon interactions with adsorbates. (d) Characterization of adsorption and (thermal and photo) reaction of molecules with nitro-endgroups, (e) Exploring the possibility of modifying planar model photocatalyst surfaces with graphene to enable fundamental studies on reported enhanced photocatalytic activities of graphene modified transition metal oxides, (f) gained fundamental understanding on the role of crystallographic polymorphs of the same material for their photocatalytic activities.« less

Developing teachers' understanding of molecular biology: Building a foundation for students.

PubMed

Boulay, Rachel; Parisky, Alex; Campbell, Chris

2010-01-01

Molecular biology often uses participation in active research laboratories as a form of educational training. However, this approach to learning severely restricts access. As a way of addressing this need, the University of Hawaii launched a project to expand this model to include newly developed online training materials in addition to a hands-on laboratory experience. This paper further explores the process of material development and assessment plans. A pilot case study of a group of advanced biology teachers who embark on learning molecular biology over a four-month period through online training materials and working side-by-side with medical researchers in a laboratory is described. Teachers were positive in reporting about the many areas they gained instruction in although some feedback suggested that the initial online materials over-emphasised abstract concepts and laboratory techniques and did not adequately connect to the active research problems or local context of most interest to teachers and students. The experiences of the teachers are shared in an effort to gain insight on how teachers perceive their participation in the study.

Classification of soft-shell materials for leisure outdoor jackets by clo defined from thermal properties testing

NASA Astrophysics Data System (ADS)

Tesinova, P.; Steklova, P.; Duchacova, T.

2017-10-01

Materials for outdoor activities are produced in various combinations and lamination helps to combine two or more components for gaining high comfort properties and lighten the structure. Producers can choose exact suitable material for construction of part or set of so called layered clothing for expected activity. Decreasing the weight of materials when preserving of high quality of water-vapour permeability, wind resistivity and hydrostatic resistivity and other comfort and usage properties is a big task nowadays. This paper is focused on thermal properties as an important parameter for being comfort during outdoor activities. Softshell materials were chosen for testing and computation of clo. Results compared with standardised clo table helps us to classify thermal insulation of the set of fabrics when defining proper clothing category.

Biological Activity of Mesoporous Dendrimer-Coated Titanium Dioxide: Insight on the Role of the Surface-Interface Composition and the Framework Crystallinity.

PubMed

Milowska, Katarzyna; Rybczyńska, Aneta; Mosiolek, Joanna; Durdyn, Joanna; Szewczyk, Eligia M; Katir, Nadia; Brahmi, Younes; Majoral, Jean-Pierre; Bousmina, Mosto; Bryszewska, Maria; El Kadib, Abdelkrim

2015-09-16

Hitherto, the field of nanomedicine has been overwhelmingly dominated by the use of mesoporous organosilicas compared to their metal oxide congeners. Despite their remarkable reactivity, titanium oxide-based materials have been seldom evaluated and little knowledge has been gained with respect to their "structure-biological activity" relationship. Herein, a fruitful association of phosphorus dendrimers (both "ammonium-terminated" and "phosphonate-terminated") and titanium dioxide has been performed by means of the sol-gel process, resulting in mesoporous dendrimer-coated nanosized crystalline titanium dioxide. A similar organo-coating has been reproduced using single branch-mimicking dendrimers that allow isolation of an amorphous titanium dioxide. The impact of these materials on red blood cells was evaluated by studying cell hemolysis. Next, their cytotoxicity toward B14 Chinese fibroblasts and their antimicrobial activity were also investigated. Based on their variants (cationic versus anionic terminal groups and amorphous versus crystalline titanium dioxide phase), better understanding of the role of the surface-interface composition and the nature of the framework has been gained. No noticeable discrimination was observed for amorphous and crystalline material. In contrast, hemolysis and cytotoxicity were found to be sensitive to the nature of the interface composition, with the ammonium-terminated dendrimer-coated titanium dioxide being the most hemolytic and cytotoxic material. This surface-functionalization opens the door for creating a new synergistic machineries mechanism at the cellular level and seems promising for tailoring the biological activity of nanosized organic-inorganic hybrid materials.

Modeling of the self-Q-switching behavior of lasers based on chromium doped active material

NASA Astrophysics Data System (ADS)

Fromager, M.; Ameur, K. Aı̈t

2001-05-01

The aim of this paper is to study the influence of the direct coupling of the average lattice strains to the active ions on the behavior of a gain switching laser based on chromium doped active material. It is found that the resulting nonlinear time-dependent lensing effect combined with an internal aperture behaves as a saturable absorber. A resulting self-Q-switching effect is observed from the calculated output laser pulses. The results of our modeling are in agreement with experimental observations already reported in literature.

Development of optically pumped DBR-free semiconductor disk lasers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor

2017-03-01

Semiconductor disk lasers (SDLs) are attractive for applications requiring good beam quality, wavelength versatility, and high output powers. Typical SDLs utilize the active mirror geometry, where a semiconductor DBR is integrated with the active region by growth or post-growth bonding. This imposes restrictions for the SDL design, like material system choice, thermal management, and effective gain bandwidth. In DBR-free geometry, these restrictions can be alleviated. An integrated gain model predicts DBR-free geometry with twice the gain bandwidth of typical SDLs, which has been experimentally verified with active regions near 1 μm and 1.15 μm. The lift-off and bonding technique enables the integration of semiconductor active regions with arbitrary high quality substrates, allowing novel monolithic geometries. Bonding an active region onto a straight side of a commercial fused silica right angle prism, and attaching a high reflectivity mirror onto the hypotenuse side, with quasi CW pumping at 780 nm, lasing operation was achieved at 1037 nm with 0.2 mW average power at 1.6 mW average pump power. Laser dynamics show that thermal lens generation in the active region bottlenecks the laser efficiency. Investigations on total internal reflection based monolithic ring cavities are ongoing. These geometries would allow the intracavity integration of 2D materials or other passive absorbers, which could be relevant for stable mode locking. Unlike typical monolithic microchip SDLs, with the evanescent wave coupling technique, these monolithic geometries allow variable coupling efficiency.

School Radio: The Attention and Involvement of Teenage Pupils and Students.

ERIC Educational Resources Information Center

Armour, Charles

1978-01-01

Considers the problems of gaining the attention of students in the 12 to 20 age group when listening to radio as a class activity. Preparations for listening to radio in school, listener motivation, acceptable programs, teacher and student activities, and supporting visual materials are discussed. (JEG)

Adaptive wing static aeroelastic roll control

NASA Astrophysics Data System (ADS)

Ehlers, Steven M.; Weisshaar, Terrence A.

1993-09-01

Control of the static aeroelastic characteristics of a swept uniform wing in roll using an adaptive structure is examined. The wing structure is modeled as a uniform beam with bending and torsional deformation freedom. Aerodynamic loads are obtained from strip theory. The structure model includes coefficients representing torsional and bending actuation provided by embedded piezoelectric material layers. The wing is made adaptive by requiring the electric field applied to the piezoelectric material layers to be proportional to the wing root loads. The proportionality factor, or feedback gain, is used to control static aeroelastic rolling properties. Example wing configurations are used to illustrate the capabilities of the adaptive structure. The results show that rolling power, damping-in-roll and aileron effectiveness can be controlled by adjusting the feedback gain. And that dynamic pressure affects the gain required. Gain scheduling can be used to set and maintain rolling properties over a range of dynamic pressures. An adaptive wing provides a method for active aeroelastic tailoring of structural response to meet changing structural performance requirements during a roll maneuver.

Gain and refractive index dynamics in p-doped InAs quantum dash semiconductor optical amplifiers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komolibus, Katarzyna; Tyndall National Institute, University College Cork, Cork T12 R5CP; Piwonski, Tomasz, E-mail: tomasz.piwonski@tyndall.ie

The ultrafast carrier dynamics in a p-doped dash-in-a-well structure at 1.5 μm is experimentally investigated. An analysis of the timescales related to carrier relaxation and escape processes as well as the “dynamical” linewidth enhancement factor is presented and compared with results obtained from similar un-doped materials. Intentional p-doping of the active region results in an enhancement of the intermediate timescale of the gain dynamics associated with phonon-assisted electron capture and a reduction of the α-factor due to increased differential gain.

Biosynthesis, structural architecture and biotechnological potential of bacterial tannase: a molecular advancement.

PubMed

Jana, Arijit; Halder, Suman Kumar; Banerjee, Amrita; Paul, Tanmay; Pati, Bikash Ranjan; Mondal, Keshab Chandra; Das Mohapatra, Pradeep Kumar

2014-04-01

Tannin-rich materials are abundantly generated as wastes from several agroindustrial activities. Therefore, tannase is an interesting hydrolase, for bioconversion of tannin-rich materials into value added products by catalyzing the hydrolysis of ester and depside bonds and unlocked a new prospect in different industrial sectors like food, beverages, pharmaceuticals, etc. Microorganisms, particularly bacteria are one of the major sources of tannase. In the last decade, cloning and heterologous expression of novel tannase genes and structural study has gained momentum. In this article, we have emphasized critically on bacterial tannase that have gained worldwide research interest for their diverse properties. The present paper delineate the developments that have taken place in understanding the role of tannase action, microbial sources, various cultivation aspects, downstream processing, salient biochemical properties, structure and active sites, immobilization, efforts in cloning and overexpression and with special emphasis on recent molecular and biotechnological achievements. Copyright © 2014 Elsevier Ltd. All rights reserved.

Digestion, growth and reproductive performance of the zoophytophagous rove beetle Philonthus quisquiliarius (Coleoptera: Staphylinidae) fed on animal and plant based diets.

PubMed

García, Matías; Farinós, Gema P; Castañera, Pedro; Ortego, Félix

2012-10-01

The zoophytophagous feeding habits of larvae and adults of the rove beetle, Philonthus quisquiliarius (Gyllenhal) (Coleoptera: Staphylinidae), are reported for the first time. This study evaluates the effects of different feeding regimes on its growth and reproductive performance (i.e., larval growth, adult weight gain, consumption, fecundity and fertility) and digestive physiology. Larvae presented similar growth rates when fed on living animal or on green plant material for 48 h. However, higher consumption rates and lower efficiencies of conversion of digested matter to body mass were obtained when leaves were consumed. Adults presented also positive weight gains regardless of the food consumed (plant or animal material). Interestingly, the highest weight gain rate and efficiency of digestion resulted when adults fed on a rearing diet containing nutrients from both animals and plants. Moreover, we have found negative effects upon P. quisquiliarius fecundity and fertility when supplemental plant nutrients were removed from the optimum rearing diet. Physiological adaptations to allow trophic switching between predation and phytophagy have been found, such as the higher ratio of α-amylase activity to protease activity to deal with the inverted protein-carbohydrate ratio of plant versus animal tissues. Furthermore, this species has an arsenal of digestive proteases whose activity is affected by the type of diet ingested. All together, our results suggest that P. quisquiliarius needs certain nutrients, which are obtained only from plant material. This knowledge will help to understand the complex trophic interactions that occur in agroecosystems. Copyright © 2012 Elsevier Ltd. All rights reserved.

Temperature dependence of material gain of InGaAsP/InP nano-heterostructure

NASA Astrophysics Data System (ADS)

Yadav, Rashmi; Alvi, P. A.

2014-04-01

This paper deals with temperature dependent study on material gain of InGaAsP/InP lasing nano-heterostructure with in TE mode. The model is based on simple separate confinement heterostructure (SCH). Material gain for the structure has been simulated for below and above the room temperatures. Different behaviors of the material gain for both ranges of the temperature have been reported in this paper. The results obtained in the simulation of the heterostructures suggest that only the shift in maximum gain takes place that appears at the lasing wavelength ˜ 1.40 μm.

Improvements in Students' Understanding from Increased Implementation of Active Learning Strategies

NASA Astrophysics Data System (ADS)

Hayes-Gehrke, Melissa N.; Prather, E. E.; Rudolph, A. L.; Collaboration of Astronomy Teaching Scholars CATS

2011-01-01

Many instructors are hesitant to implement active learning strategies in their introductory astronomy classrooms because they are not sure which techniques they should use, how to implement those techniques, and question whether the investment in changing their course will really bring the advertised learning gains. We present an example illustrating how thoughtful and systematic implementation of active learning strategies into a traditionally taught Astro 101 class can translate into significant increases in students' understanding. We detail the journey of one instructor, over several years, as she changes the instruction and design of her course from one that focuses almost exclusively on lecture to a course that provides an integrated use of several active learning techniques such as Lecture-Tutorials and Think-Pair-Share questions. The students in the initial lecture-only course achieved a low normalized gain score of only 0.2 on the Light and Spectroscopy Concept Inventory (LSCI), while the students in the re-designed learner-centered course achieved a significantly better normalized gain of 0.43. This material is based upon work supported by the National Science Foundation under Grant No. 0715517, a CCLI Phase III Grant for the Collaboration of Astronomy Teaching Scholars (CATS), and Grant No. 0847170, a PAARE Grant for the Calfornia-Arizona Minority Partnership for Astronomy Research and Education (CAMPARE). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

The Effects of Gain- versus Loss-Framed Messages Following Health Risk Information on Physical Activity in Individuals With Multiple Sclerosis.

PubMed

Lithopoulos, Alexander; Bassett-Gunter, Rebecca L; Martin Ginis, Kathleen A; Latimer-Cheung, Amy E

2017-06-01

Few people with multiple sclerosis engage in physical activity. Messaging interventions may motivate more physical activity among these individuals. The purpose of this online study was to evaluate an intervention presenting participants with multiple sclerosis (N = 237) with risk information (i.e., information demonstrating people with multiple sclerosis are more likely to experience certain health issues) or no risk information followed by gain- or loss-framed physical activity messages. Participants completed questionnaires on Days 1, 6, and 28 and received information material on Days 2-5. The dependent variables were as follows: physical activity intentions and behavior, response and task efficacy, perceived threat (i.e., perception of threat to health issues relevant to people with multiple sclerosis), and avoidance (i.e., avoiding thinking about/doing something about the health issues presented in the messages). Analyses indicated physical activity and response efficacy increased over time. Also, participants receiving risk information had higher levels of physical activity and perceived threat. However, manipulation checks showed no differences between participants regarding perceptions of risk information or gain/loss-framed messages. Despite the lack of impact of the framing intervention, this study suggests that a brief informational intervention can positively influence physical activity and certain correlates of physical activity among people with multiple sclerosis.

Learn before Lecture: A Strategy that Improves Learning Outcomes in a Large Introductory Biology Class

ERIC Educational Resources Information Center

Moravec, Marin; Williams, Adrienne; Aguilar-Roca, Nancy; O'Dowd, Diane K.

2010-01-01

Actively engaging students in lecture has been shown to increase learning gains. To create time for active learning without displacing content we used two strategies for introducing material before class in a large introductory biology course. Four to five slides from 2007/8 were removed from each of three lectures in 2009 and the information…

Creating Interactive Teaching Methods for ASTRO 101 That Really Work

NASA Astrophysics Data System (ADS)

Prather, E. E.; Adams, J. P.; Bailey, J. M.; Huggins, D.; Jones, L. V.; Slater, T. F.

2004-05-01

Acknowledging that lecture-based teaching methods are insufficient at promoting significant conceptual gains for students in the introductory astronomy course for non-science majors (ASTRO 101) is only the first step. But then, what can you do besides lecture? The Conceptual Astronomy and Physics Education Research (CAPER) Team at the University of Arizona has been developing and conducting research on the effectiveness of learner-centered instructional materials that put students in an active role in the classroom. With the support of an NSF CCLI (9952232) and NSF Geosciences Education (9907755) awards, we have designed and field-tested a set of innovative instructional materials called Lecture Tutorials. These Lecture Tutorial activities are intended for use with collaborative student learning groups and are designed specifically to be easily integrated into existing conventional lecture-based courses. As such, these instructional materials directly address the needs of heavily loaded teaching faculty in that they offer effective, learner-centered, classroom-ready activities that do not require any outside equipment/staffing or a drastic course revision for implementation. Each 15-minute Lecture-Tutorial poses a carefully crafted sequence of conceptually challenging, Socratic-dialogue driven questions, along with graphs and data tables, all designed to encourage students to reason critically about conceptually challenging and commonly taught topics in astronomy. The materials are based on research into student beliefs and reasoning difficulties and make use of a conceptual change instructional framework that promotes the intellectual engagement of students. Our research into the effectiveness of the Lecture Tutorials illustrates that traditional lectures alone make unsatisfactory gains on student understanding; however, supplementing traditional instruction with the lecture tutorials helps students make impressive conceptual gains over traditional instruction. In addition to the Lecture Tutorials we will discuss our current development of another set of engaging conceptual exercises that may have special benefit in the ASTRO 101 classroom known as Ranking Tasks.

The Synthesis of Photocatalyst Material ZnO using the Simple Sonication Method

NASA Astrophysics Data System (ADS)

Faradis, R.; Azizah, E. N.; Marella, S. D.; Aini, N.; Prasetyo, A.

2018-03-01

ZnO is well known as photocatalyst material therefore potentially to applied in many purposes. The particle size of photocatalyst material influenced the catalytic activities. In this research, ZnO was synthesized using the simple sonication method to obtain the the smaller particle with sonication time variation respectively: 30, 60, 160, 360 minute. X-ray diffraction data showed that the synthesized material have wurtzite structure with space group P63 mc. The synthesized ZnO with 30 minutes sonication time produced the smallest particle size and have the lowest band gap energy (2.79 eV). The photocatalytic test at methylene blue also showed that the optimum activity was gained from ZnO which synthesized at 30 minute sonication time (degradation percentage of metylene blue is 77.93%).

10 CFR 73.25 - Performance capabilities for physical protection of strategic special nuclear material in transit.

Code of Federal Regulations, 2013 CFR

2013-01-01

... as conditions warrant. (2) Detect and delay any unauthorized attempt to gain access or introduce... of § 73.20(a). (3) Detect attempts to gain unauthorized access or introduce unauthorized materials... system shall: (1) Detect attempts to gain unauthorized entry or introduce unauthorized materials into...

10 CFR 73.25 - Performance capabilities for physical protection of strategic special nuclear material in transit.

Code of Federal Regulations, 2010 CFR

2010-01-01

... as conditions warrant. (2) Detect and delay any unauthorized attempt to gain access or introduce... of § 73.20(a). (3) Detect attempts to gain unauthorized access or introduce unauthorized materials... system shall: (1) Detect attempts to gain unauthorized entry or introduce unauthorized materials into...

10 CFR 73.25 - Performance capabilities for physical protection of strategic special nuclear material in transit.

Code of Federal Regulations, 2014 CFR

2014-01-01

... as conditions warrant. (2) Detect and delay any unauthorized attempt to gain access or introduce... of § 73.20(a). (3) Detect attempts to gain unauthorized access or introduce unauthorized materials... system shall: (1) Detect attempts to gain unauthorized entry or introduce unauthorized materials into...

Combined optical gain and degradation measurements in DCM2 doped Tris-(8-hydroxyquinoline)aluminum thin-films

NASA Astrophysics Data System (ADS)

Čehovski, Marko; Döring, Sebastian; Rabe, Torsten; Caspary, Reinhard; Kowalsky, Wolfgang

2016-04-01

Organic laser sources offer the opportunity to integrate flexible and widely tunable lasers in polymer waveguide circuits, e.g. for Lab-on-Foil applications. Therefore, it is necessary to understand gain and degradation processes for long-term operation. In this paper we address the challenge of life-time (degradation) measurements of photoluminescence (PL) and optical gain in thin-film lasers. The well known guest-host system of aluminum-chelate Alq3 (Tris-(8-hydroxyquinoline)aluminum) as host material and the laser dye DCM2 (4-(Dicyanomethylene)-2- methyl-6-julolidyl-9-enyl-4H-pyran) as guest material is employed as laser active material. Sample layers have been built up by co-evaporation in an ultrahigh (UHV) vacuum chamber. 200nm thick films of Alq3:DCM2 with different doping concentrations have been processed onto glass and thermally oxidized silicon substrates. The gain measurements have been performed by the variable stripe length (VSL) method. This measurement technique allows to determine the thin-film waveguide gain and loss, respectively. For the measurements the samples were excited with UV irradiation (ƛ = 355nm) under nitrogen atmosphere by a passively Q-switched laser source. PL degradation measurements with regard to the optical gain have been done at laser threshold (approximately 3 μJ/cm2), five times above laser threshold and 10 times above laser threshold. A t50-PL lifetime of > 107 pulses could be measured at a maximum excitation energy density of 32 μJ/cm2. This allows for a detailed analysis of the gain degradation mechanism and therefore of the stimulated cross section. Depending on the DCM2 doping concentration C the stimulated cross section was reduced by 35 %. Nevertheless, the results emphasizes the necessity of the investigation of degradation processes in organic laser sources for long-term applications.

Activities for Teaching Russian and Soviet Studies in the High School. Updated Edition.

ERIC Educational Resources Information Center

Cole, Robert A., Ed.; Vaillant, Janet G., Ed.

These teacher-developed activities help the student to gain a greater awareness of the richness of Russian history and the Soviet past. New materials have been added from the original version and much has been updated. The volume is not a full curriculum but can be integrated into existing study of the world region. The book is divided into five…

Method and system for edge cladding of laser gain media

DOEpatents

Bayramian, Andrew James; Caird, John Allyn; Schaffers, Kathleen Irene

2014-03-25

A gain medium operable to amplify light at a gain wavelength and having reduced transverse ASE includes an input surface and an output surface opposing the input surface. The gain medium also includes a central region including gain material and extending between the input surface and the output surface along a longitudinal optical axis of the gain medium. The gain medium further includes an edge cladding region surrounding the central region and extending between the input surface and the output surface along the longitudinal optical axis of the gain medium. The edge cladding region includes the gain material and a dopant operable to absorb light at the gain wavelength.

Doing the Math: Supporting Student Justifications

ERIC Educational Resources Information Center

James, Carolyn; Philiben, Lyn; Knievel, Molly

2016-01-01

Teachers have found that engaging students in justification can help students deepen and retain mathematical knowledge, gain a greater sense of ownership over the material, and improve communication and representation skills (Staples, Bartlo, and Thanheiser 2012). Student engagement in a justification activity can also lead to more equitable…

Decreasing redox voltage of terephthalate-based electrode material for Li-ion battery using substituent effect

NASA Astrophysics Data System (ADS)

Lakraychi, A. E.; Dolhem, F.; Djedaïni-Pilard, F.; Thiam, A.; Frayret, C.; Becuwe, M.

2017-08-01

The preparation and assessment versus lithium of a functionalized terephthalate-based as a potential new negative electrode material for Li-ion battery is presented. Inspired from molecular modelling, a decrease in redox potential is achieved through the symmetrical adjunction of electron-donating fragments (-CH3) on the aromatic ring. While the electrochemical activity of this organic material was maximized when used as nanocomposite and without any binder, the potential is furthermore lowered by 110 mV upon functionalization, consistently with predicted value gained from DFT calculations.

Microscopic model for intersubband gain from electrically pumped quantum-dot structures

DOE PAGES

Michael, Stephan; Chow, Weng Wah; Schneider, Han Christian

2014-10-03

We study theoretically the performance of electrically pumped self-organized quantum dots as a gain material in the mid-infrared range at room temperature. We analyze an AlGaAs/InGaAs based structure composed of dots-in-a-well sandwiched between two quantum wells. We numerically analyze a comprehensive model by combining a many-particle approach for electronic dynamics with a realistic modeling of the electronic states in the whole structure. We investigate the gain both for quasi-equilibrium conditions and current injection. We find, comparing different structures, that steady-state gain can only be realized by an efficient extraction process, which prevents an accumulation of electrons in continuum states, thatmore » make the available scattering pathways through the quantum-dot active region too fast to sustain inversion.« less

Antimicrobial properties of conventional restorative filling materials and advances in antimicrobial properties of composite resins and glass ionomer cements-A literature review.

PubMed

Farrugia, Cher; Camilleri, Josette

2015-04-01

It has been reported that complete caries removal from cavities during restoration of teeth is difficult. Furthermore with the tissue saving approach it is expected that more of the saved affected tissue will possibly harbor more residual bacteria. Antimicrobial restorative filling materials would be ideal to prevent the spread of caries after completion of tooth restoration, thus preventing recurrent decay and eventually restoration failure. This paper reviews the literature on the antimicrobial properties of dental restorative filling materials. Pubmed searches on the antibacterial properties of restorative materials were carried out. Keywords were chosen to assess antibacterial properties of conventional filling materials. Methods of introducing antimicrobial agents in restorative materials were also reviewed together with the methodology used to assess antimicrobial activity. 174 articles from 1983 till 2014 were included. Adhesive materials have decreased antimicrobial activity when compared to amalgams and zinc oxides. Several techniques have been employed in order to increase the antimicrobial activity of restorative materials. Although antimicrobial activity of restorative materials is important, the introduction of antimicrobial agents/techniques should not be at the expense of other material properties. Environmental changes within a material may affect the bacterial response to the antimicrobial. Bacterial adhesion to the restorative materials should be assessed. Long term assessment of antimicrobial activity is important and is clinically relevant. The use of antimicrobial dental materials is important unless such characteristics are gained to the detriment of other material properties. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Simulating Dinosaur Digestion in the Classroom.

ERIC Educational Resources Information Center

Peczkis, Jan

1992-01-01

Describes an activity for use with a chapter on dinosaurs, prehistoric life, or digestion in which children make simulated dinosaur stomachs to gain hands-on experience about the theory of gastroliths, or stomach stones. Presents teacher information about the digestive processes in birds and dinosaurs. Discusses materials needed, objectives,…

Male Reproductive System.

ERIC Educational Resources Information Center

Turkington, B. A.

This autoinstructional lesson deals with the study of the human body with emphasis on the life process of reproduction. It is a learning activity included in high school biology or health education classes. The behavioral objectives are listed and the equipment and materials needed to help the student gain these objectives are also included in the…

Progress in Materials and Component Development for Advanced Lithium-ion Cells for NASA's Exploration Missions

NASA Technical Reports Server (NTRS)

Reid, Concha, M.; Reid, Concha M.

2011-01-01

Vehicles and stand-alone power systems that enable the next generation of human missions to the Moon will require energy storage systems that are safer, lighter, and more compact than current state-of-the- art (SOA) aerospace quality lithium-ion (Li-ion) batteries. NASA is developing advanced Li-ion cells to enable or enhance the power systems for the Altair Lunar Lander, Extravehicular Activities spacesuit, and rovers and portable utility pallets for Lunar Surface Systems. Advanced, high-performing materials are required to provide component-level performance that can offer the required gains at the integrated cell level. Although there is still a significant amount of work yet to be done, the present state of development activities has resulted in the synthesis of promising materials that approach the ultimate performance goals. This report on interim progress of the development efforts will elaborate on the challenges of the development activities, proposed strategies to overcome technical issues, and present performance of materials and cell components.

Insights on activation enthalpy for non-Schmid slip in body-centered cubic metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hale, Lucas M.; Lim, Hojun; Zimmerman, Jonathan A.

2014-12-18

We use insights gained from atomistic simulation to develop an activation enthalpy model for dislocation slip in body-centered cubic iron. Furthermore, using a classical potential that predicts dislocation core stabilities consistent with ab initio predictions, we quantify the non-Schmid stress-dependent effects of slip. The kink-pair activation enthalpy is evaluated and a model is identified as a function of the general stress state. Thus, our model enlarges the applicability of the classic Kocks activation enthalpy model to materials with non-Schmid behavior.

Coming of Age. Nature. Teacher's Guide.

ERIC Educational Resources Information Center

Brown, Jordan; Barker, Lucia

This curriculum guide was developed for use with public television's Nature series. The materials in the guide are designed to help students actively participate in the study and experience of nature. Students are encouraged to view the programs as naturalists would in order to gain a better understanding of animals, their habits and habitats, and…

75 FR 75666 - Office of Special Education and Rehabilitative Services Overview Information; National Institute...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-06

... directed toward producing (1) new scientific knowledge, or (2) better understanding of the subject, problem studied, or body of knowledge. In carrying out a development activity under an FI project development grant, a grantee must use knowledge and understanding gained from research to create materials, devices...

20 CFR 404.316 - When entitlement to disability benefits begins and ends.

Code of Federal Regulations, 2014 CFR

2014-04-01

... benefits for any months in which you do substantial gainful activity. (e) If drug addiction or alcoholism... addiction or alcoholism is not available, months before March 1995, and months for which your benefit.... (f) If drug addiction or alcoholism is a contributing factor material to the determination of...

20 CFR 404.316 - When entitlement to disability benefits begins and ends.

Code of Federal Regulations, 2011 CFR

2011-04-01

... benefits for any months in which you do substantial gainful activity. (e) If drug addiction or alcoholism... addiction or alcoholism is not available, months before March 1995, and months for which your benefit.... (f) If drug addiction or alcoholism is a contributing factor material to the determination of...

20 CFR 404.316 - When entitlement to disability benefits begins and ends.

Code of Federal Regulations, 2012 CFR

2012-04-01

... benefits for any months in which you do substantial gainful activity. (e) If drug addiction or alcoholism... addiction or alcoholism is not available, months before March 1995, and months for which your benefit.... (f) If drug addiction or alcoholism is a contributing factor material to the determination of...

20 CFR 404.316 - When entitlement to disability benefits begins and ends.

Code of Federal Regulations, 2013 CFR

2013-04-01

... benefits for any months in which you do substantial gainful activity. (e) If drug addiction or alcoholism... addiction or alcoholism is not available, months before March 1995, and months for which your benefit.... (f) If drug addiction or alcoholism is a contributing factor material to the determination of...

The "Balance Intervention" for Promoting Caloric Compensatory Behaviours in Response to Overeating: A Formative Evaluation

ERIC Educational Resources Information Center

Wammes, Birgitte; Breedveld, Boudewijn; Kremers, Stef; Brug, Johannes

2006-01-01

To help people prevent weight gain, the Netherlands Nutrition Centre initiated the "balance intervention", which promotes moderation of food intake and/or increased physical activity in response to occasions of overeating. The aim of this study was to determine whether intervention materials were appreciated, encouraged information…

Political Science and Speech Communication--A Team Approach to Teaching Political Communication.

ERIC Educational Resources Information Center

Blatt, Stephen J.; Fogel, Norman

This paper proposes making speech communication more interdisciplinary and, in particular, combining political science and speech in a team-taught course in election campaigning. The goals, materials, activities, and plan of such a course are discussed. The goals include: (1) gaining new insights into the process of contemporary campaigns and…

Learning from Science: Case Studies of Science Offerings in Afterschool Programs

ERIC Educational Resources Information Center

Lundh, Patrik; House, Ann; Means, Barbara; Harris, Christopher J.

2013-01-01

Afterschool programs have increasingly gained attention as settings that can help enrich students' science learning. Even though science is widely included in afterschool activities, sites often lack adequate materials and staff know-how to implement quality science. To address this need, this article examines afterschool science in light of the…

Recommendations for the Recruitment and Retention of Transfer Students

ERIC Educational Resources Information Center

Kippenhan, Heidi

2004-01-01

The purpose of this article is to gain practical knowledge about a population of students that is vital and necessary to any university community. The history of transfer students lends itself to the assumption that there is no targeted marketing, specific recruitment materials, equity in events or outreach activities, or equal data gathered in…

Red, green, and blue lasing enabled by single-exciton gain in colloidal quantum dot films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurmikko, Arto V.; Dang, Cuong

The methods and materials described herein contemplate the use films of colloidal quantum dots as a gain medium in a vertical-cavity surface-emitting laser. The present disclosure demonstrates a laser with single-exciton gain in the red, green, and blue wavelengths. Leveraging this nanocomposite gain, the results realize a significant step toward full-color single-material lasers.

Materials for suspension (semi-solid) electrodes for energy and water technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hatzell, Kelsey B.; Boota, Muhammad; Gogotsi, Yury

2015-01-01

Suspension or semi-solid electrodes have recently gained increased attention for large-scale applications such as grid energy storage, capacitive water deionization, and wastewater treatment. A suspension electrode is a multiphase material system comprised of an active (charge storing) material suspended in ionic solution (electrolyte). Gravimetrically, the electrolyte is the majority component and aids in physical transport of the active material. For the first time, this principle enables, scalability of electrochemical energy storage devices (supercapacitors and batteries) previously limited to small and medium scale applications. This critical review describes the ongoing material challenges encompassing suspension-based systems. The research described here combines classicalmore » aspects of electrochemistry, colloidal science, material science, fluid mechanics, and rheology to describe ion and charge percolation, adsorption of ions, and redox charge storage processes in suspension electrodes. Our review summarizes the growing inventory of material systems, methods and practices used to characterize suspension electrodes, and describes universal material system properties (rheological, electrical, and electrochemical) that are pivotal in the design of high performing systems. We include a discussion of the primary challenges and future research directions.« less

GaAsP/InGaP HBTs grown epitaxially on Si substrates: Effect of dislocation density on DC current gain

NASA Astrophysics Data System (ADS)

Heidelberger, Christopher; Fitzgerald, Eugene A.

2018-04-01

Heterojunction bipolar transistors (HBTs) with GaAs0.825P0.175 bases and collectors and In0.40Ga0.60P emitters were integrated monolithically onto Si substrates. The HBT structures were grown epitaxially on Si via metalorganic chemical vapor deposition, using SiGe compositionally graded buffers to accommodate the lattice mismatch while maintaining threading dislocation density at an acceptable level (˜3 × 106 cm-2). GaAs0.825P0.175 is used as an active material instead of GaAs because of its higher bandgap (increased breakdown voltage) and closer lattice constant to Si. Misfit dislocation density in the active device layers, measured by electron-beam-induced current, was reduced by making iterative changes to the epitaxial structure. This optimized process culminated in a GaAs0.825P0.175/In0.40Ga0.60P HBT grown on Si with a DC current gain of 156. By considering the various GaAsP/InGaP HBTs grown on Si substrates alongside several control devices grown on GaAs substrates, a wide range of threading dislocation densities and misfit dislocation densities in the active layers could be correlated with HBT current gain. The effect of threading dislocations on current gain was moderated by the reduction in minority carrier lifetime in the base region, in agreement with existing models for GaAs light-emitting diodes and photovoltaic cells. Current gain was shown to be extremely sensitive to misfit dislocations in the active layers of the HBT—much more sensitive than to threading dislocations. We develop a model for this relationship where increased base current is mediated by Fermi level pinning near misfit dislocations.

Enhanced gain and output power of a sealed-off rf-excited CO2 waveguide laser with gold-plated electrodes

NASA Astrophysics Data System (ADS)

Heeman-Ilieva, M. B.; Udalov, Yu. B.; Hoen, K.; Witteman, W. J.

1994-02-01

The small-signal gain and the laser output power have been measured in a cw sealed-off rf-excited CO2 waveguide laser for two different electrode materials, gold-plated copper and aluminum, at several excitation frequencies, gas pressures and mixture compositions. In the case of the gold-plated electrodes an enhancement of the gain up to a factor of 2 and the output power up to a factor of 1.4 with time at a frequency of 190 MHz and 60 Torr of 1:1:5+5% (CO2:N2:He+Xe) mixture is observed. This is believed to be the result of the gold catalytic activities which are favored by increased electrode temperatures and helium rich gas compositions.

Variation in behavioral engagement during an active learning activity leads to differential knowledge gains in college students.

PubMed

LaDage, Lara D; Tornello, Samantha L; Vallejera, Jennilyn M; Baker, Emily E; Yan, Yue; Chowdhury, Anik

2018-03-01

There are many pedagogical techniques used by educators in higher education; however, some techniques and activities have been shown to be more beneficial to student learning than others. Research has demonstrated that active learning and learning in which students cognitively engage with the material in a multitude of ways result in better understanding and retention. The aim of the present study was to determine which of three pedagogical techniques led to improvement in learning and retention in undergraduate college students. Subjects partook in one of three different types of pedagogical engagement: hands-on learning with a model, observing someone else manipulate the model, and traditional lecture-based presentation. Students were then asked to take an online quiz that tested their knowledge of the new material, both immediately after learning the material and 2 wk later. Students who engaged in direct manipulation of the model scored higher on the assessment immediately after learning the material compared with the other two groups. However, there were no differences among the three groups when assessed after a 2-wk retention interval. Thus active learning techniques that involve direct interaction with the material can lead to learning benefits; however, how these techniques benefit long-term retention of the information is equivocal.

The study of electromagnetic wave propagation in photonic crystals via planewave based transfer (scattering) matrix method with active gain material applications

NASA Astrophysics Data System (ADS)

Li, Ming

In this dissertation, a set of numerical simulation tools are developed under previous work to efficiently and accurately study one-dimensional (1D), two-dimensional (2D), 2D slab and three-dimensional (3D) photonic crystal structures and their defects effects by means of spectrum (transmission, reflection, absorption), band structure (dispersion relation), and electric and/or magnetic fields distribution (mode profiles). Further more, the lasing property and spontaneous emission behaviors are studied when active gain materials are presented in the photonic crystal structures. First, the planewave based transfer (scattering) matrix method (TMM) is described in every detail along with a brief review of photonic crystal history (Chapter 1 and 2). As a frequency domain method, TMM has the following major advantages over other numerical methods: (1) the planewave basis makes Maxwell's Equations a linear algebra problem and there are mature numerical package to solve linear algebra problem such as Lapack and Scalapack (for parallel computation). (2) Transfer (scattering) matrix method make 3D problem into 2D slices and link all slices together via the scattering matrix (S matrix) which reduces computation time and memory usage dramatically and makes 3D real photonic crystal devices design possible; and this also makes the simulated domain no length limitation along the propagation direction (ideal for waveguide simulation). (3) It is a frequency domain method and calculation results are all for steady state, without the influences of finite time span convolution effects and/or transient effects. (4) TMM can treat dispersive material (such as metal at visible light) naturally without introducing any additional computation; and meanwhile TMM can also deal with anisotropic material and magnetic material (such as perfectly matched layer) naturally from its algorithms. (5) Extension of TMM to deal with active gain material can be done through an iteration procedure with gain material expressed by electric field dependent dielectric constant. Next, the concepts of spectrum interpolation (Chapter 3), higher-order incident (Chapter 4) and perfectly matched layer (Chapter 5) are introduced and applied to TMM, with detailed simulation for 1D, 2D, and 3D photonic crystal examples. Curvilinear coordinate transform is applied to the Maxwell's Equations to study waveguide bend (Chapter 6). By finding the phase difference along propagation direction at various XY plane locations, the behaviors of electromagnetic wave propagation (such as light bending, focusing etc) can be studied (Chapter 7), which can be applied to diffractive optics for new devices design. Numerical simulation tools for lasing devices are usually based on rate equations which are not accurate above the threshold and for small scale lasing cavities (such as nano-scale cavities). Recently, we extend the TMM package function to include the capacity of dealing active gain materials. Both lasing (above threshold) and spontaneous emission (below threshold) can be studied in the frame work of our Gain-TMM algorithm. Chapter 8 will illustrate the algorithm in detail and show the simulation results for 3D photonic crystal lasing devices. Then, microwave experiments (mainly resonant cavity embedded at layer-by-layer woodpile structures) are performed at Chapter 9 as an efficient practical way to study photonic crystal devices. The size of photonic crystal under microwave region is at the order of centimeter which makes the fabrication easier to realize. At the same time due to the scaling property, the result of microwave experiments can be applied directly to optical or infrared frequency regions. The systematic TMM simulations for various resonant cavities are performed and consistent results are obtained when compared with microwave experiments. Besides scaling the experimental results to much smaller wavelength, designing potential photonic crystal devices for application at microwave is also an interesting and important topic. Finally, we describe the future development of TMM algorithm such as using localized functions as basis to more efficiently simulate disorder problems (Chapter 10). Future applications of photonic crystal concepts are also discussed at Chapter 10. Along with this dissertation, TMM Photonic Crystal Package User Manual and Gain TMM Photonic Crystal Package User Manual written by me, Dr. Jiangrong Cao (Canon USA) and Dr. Xinhua Hu (Ames Lab) focus more on the programming detail, software user interface, trouble shooting, and step-by-step instructions. This dissertation and the two user manuals are essential documents for TMM software package beginners and advanced users. Future software developments, new version releases and FAQs can be tracked through my web page: http://www.public.iastate.edu/~mli/ In summary, this dissertation has extended the planewave based transfer (scattering) matrix method in many aspects which make the TMM and Gain-TMM software package a powerful simulation tool in photonic crystal study. Comparisons of TMM and GTMM results with other published numerical results and experimental results indicate that TMM and GTMM is accurate and highly efficient in photonic crystal device simulation and design. (Abstract shortened by UMI.)

Variability in Reading Ability Gains as a Function of Computer-Assisted Instruction Method of Presentation

ERIC Educational Resources Information Center

Johnson, Erin Phinney; Perry, Justin; Shamir, Haya

2010-01-01

This study examines the effects on early reading skills of three different methods of presenting material with computer-assisted instruction (CAI): (1) learner-controlled picture menu, which allows the student to choose activities, (2) linear sequencer, which progresses the students through lessons at a pre-specified pace, and (3) mastery-based…

Digital Library Archaeology: A Conceptual Framework for Understanding Library Use through Artifact-Based Evaluation

ERIC Educational Resources Information Center

Nicholson, Scott

2005-01-01

Archaeologists have used material artifacts found in a physical space to gain an understanding about the people who occupied that space. Likewise, as users wander through a digital library, they leave behind data-based artifacts of their activity in the virtual space. Digital library archaeologists can gather these artifacts and employ inductive…

What's Writing Got to Do with It?: Citizen Wisdom, Civil Rights Activism, and 21st Century Community Literacy

ERIC Educational Resources Information Center

Kells, Michelle Hall

2012-01-01

This article examines what a pedagogy of public rhetoric and community literacy might look like based on an understanding of twentieth century Mexican American civil rights rhetoric. The inductive process of examining archival materials and conducting oral histories informs this discussion on the processes and challenges of gaining civic…

A Service-Learning Project on Volcanoes to Promote Critical Thinking and the Earth Science Literacy Initiative

ERIC Educational Resources Information Center

Nunn, Jeffrey A.; Braud, Janie

2013-01-01

Students in Honors Physical Geology at Louisiana State University (LSU) participated in instruction in eighth- to ninth-grade geology and geography classes in East Baton Rouge Parish Schools (EBRPS) to help meet community needs. LSU students created instructional materials and reflected on the service activity to gain a deeper understanding of…

Multiwavelength Study of Powerful New Jet Activity in the Symbiotic System R AQR

NASA Astrophysics Data System (ADS)

Karovska, Margarita

2016-10-01

We propose to carry out coordinated high-spatial resolution Chandra ACIS-S and multiwavelength (UV-Optical) HST/WFC3 observations of R Aqr, a very active symbiotic interacting binary system. Our main goal is to study the physical characteristics of the multi-scale components of the powerful jet; from the vicinity of the central binary (within a few AU) to the jet-circumbinary material interaction region (2500 AU) and beyond, and especially of the recently discovered new component of the inner jet (likely due to recent ejection of material). Our main goal is to gain new insight on early jet formation and propagation, including jet kinematics and precession.

Increasing student learning through space life sciences education

NASA Astrophysics Data System (ADS)

Moreno, Nancy P.; Kyle Roberts, J.; Tharp, Barbara Z.; Denk, James P.; Cutler, Paula H.; Thomson, William A.

2005-05-01

Scientists and educators at Baylor College of Medicine are using space life sciences research areas as themes for middle school science and health instructional materials. This paper discusses study findings of the most recent unit, Food and Fitness, which teaches concepts related to energy and nutrition through guided inquiry. Results of a field test involving more than 750 students are reported. Use of the teaching materials resulted in significant knowledge gains by students as measured on a pre/post assessment administered by teachers. In addition, an analysis of the time spent by each teacher on each activity suggested that it is preferable to conduct all of the activities in the unit with students rather than allocating the same total amount of time on just a subset of the activities.

Acoustic velocity measurements in materials using a regenerative method

DOEpatents

Laine, Edwin F.

1986-01-01

Acoustic energy is propagated through earth material between an electro-acoustic generator and a receiver which converts the received acoustic energy into electrical signals. A closed loop is formed by a variable gain amplifier system connected between the receiver and the generator. The gain of the amplifier system is increased until sustained oscillations are produced in the closed loop. The frequency of the oscillations is measured as an indication of the acoustic propagation velocity through the earth material. The amplifier gain is measured as an indication of the acoustic attenuation through the earth materials. The method is also applicable to the non-destructive testing of structural materials, such as steel, aluminum and concrete.

Acoustic-velocity measurements in materials using a regenerative method

DOEpatents

Laine, E.F.

1982-09-30

Acoustic energy is propatated through earth material between an electro-acoustic generator and a receiver which converts the received acoustic energy into electrical signals. A closed loop is formed by a variable gain amplifier system connected between the receiver and the generator. The gain of the amplifier system is increased until sustained oscillations are produced in the closed loop. The frequency of the oscillations is measured as an indication of the acoustic propagation velocity through the earth material. The amplifier gain is measured as an indication of the acoustic attenuation through the earth materials. The method is also applicable to the non-destructive testing of structural materials, such as steel, aluminum and concrete.

Mechanism of the metallic metamaterials coupled to the gain material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Zhixiang; Droulias, Sotiris; Koschny, Thomas

2014-11-10

In this study, we present evidence of strong coupling between the gain material and the metallic metamaterials. It is of vital importance to understand the mechanism of the coupling of metamaterials with the gain medium. Using a four-level gain system, the numerical pump-probe experiments are performed in several configurations (split–ring resonators (SRRs), inverse SRRs and fishnets) of metamaterials, demonstrating reduction of the resonator damping in all cases and hence the possibility for loss compensation. We find that the differential transmittance ΔT/T can be negative in different SRR configurations, such as SRRs on the top of the gain substrate, gain inmore » the SRR gap and gain covering the SRR structure, while in the fishnet metamaterial with gain ΔT/T is positive.« less

Assembling photoluminescent tri(8-quinolinolato)aluminum into periodic mesoporous organosilicas.

PubMed

Yang, Ying; Zhang, Xin; Kan, Qiubin

2013-12-01

Mesostructured and mesoporous materials are emerging as a new class of optical materials. However, their synthesis is nontrivial. In this work, periodic mesostructured metal complex-containing silicas of MCM- and SBA-type bearing homogeneously distributed photoluminescent tri(8-quinolinolato)aluminum inside the channel walls (denoted as Alq3@PMO-MCM and Alq3@PMO-SBA, respectively) have been achieved via one-pot co-assembling of inorganic/surfactant/optically active species. A comprehensive multianalytical characterization of the structural and optical properties demonstrates that both Alq3@PMO-MCM and Alq3@PMO-SBA series gainfully combine the photoluminescent properties of Alq3 with the porous features of PMOs. Regularly arranged pores provide high surface area to disperse optically active components well and render Alq3-containing PMOs promising materials for optoelectronic applications. Copyright © 2013. Published by Elsevier Inc.

Active and intelligent packaging systems for a modern society.

PubMed

Realini, Carolina E; Marcos, Begonya

2014-11-01

Active and intelligent packaging systems are continuously evolving in response to growing challenges from a modern society. This article reviews: (1) the different categories of active and intelligent packaging concepts and currently available commercial applications, (2) latest packaging research trends and innovations, and (3) the growth perspectives of the active and intelligent packaging market. Active packaging aiming at extending shelf life or improving safety while maintaining quality is progressing towards the incorporation of natural active agents into more sustainable packaging materials. Intelligent packaging systems which monitor the condition of the packed food or its environment are progressing towards more cost-effective, convenient and integrated systems to provide innovative packaging solutions. Market growth is expected for active packaging with leading shares for moisture absorbers, oxygen scavengers, microwave susceptors and antimicrobial packaging. The market for intelligent packaging is also promising with strong gains for time-temperature indicator labels and advancements in the integration of intelligent concepts into packaging materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lasing efficiency of Er-Yb-Cr-glass: A temperature study (Conference Presentation)

NASA Astrophysics Data System (ADS)

George, Simi A.; Hayden, Joseph S.; Davis, Mark J.

2017-03-01

Retina-safe operation in open-air is of high interest to the next generation of lasers that are being utilized for many industrial, defense and medical applications. Those wavelengths that are considered to be the best for retina safe operations (also called eye-safe) fall in the range between 1400nm and1800nm. This wavelength region also coincides with the low loss window of fused silica fibers used for optical fiber communications [1], where the S and C bands near 1500nm are heavily utilized for long range communications due to the lowest attenuation losses possible in the fiber. The trivalent Er ion can produce direct emission into the 1540 nm wavelength, thus, it is the rare-earth emitter of choice for many eye-safe applications. In recent years, the need for high beam quality under passive operation in open air applications have renewed interest in Er-doped bulk glasses as the gain material of choice for solid-state eye-safe lasers. The need for performance stability under a broad operating range from -400C to 1000C without active cooling is a challenge for amorphous gain materials. Moreover, there is very little known about how temperature may affect performance. In this study, we describe our first attempts to understand material behavior by systematically analyzing temperature driven variations exhibited in absorption and emission from the commercially available gain materials. As part of these investigations, we will also present our method for assessing quantum efficiency through measurements for critical evaluation from laser community at large.

Plasmonic field confinement for separate absorption-multiplication in InGaAs nanopillar avalanche photodiodes

PubMed Central

Farrell, Alan C.; Senanayake, Pradeep; Hung, Chung-Hong; El-Howayek, Georges; Rajagopal, Abhejit; Currie, Marc; Hayat, Majeed M.; Huffaker, Diana L.

2015-01-01

Avalanche photodiodes (APDs) are essential components in quantum key distribution systems and active imaging systems requiring both ultrafast response time to measure photon time of flight and high gain to detect low photon flux. The internal gain of an APD can improve system signal-to-noise ratio (SNR). Excess noise is typically kept low through the selection of material with intrinsically low excess noise, using separate-absorption-multiplication (SAM) heterostructures, or taking advantage of the dead-space effect using thin multiplication regions. In this work we demonstrate the first measurement of excess noise and gain-bandwidth product in III–V nanopillars exhibiting substantially lower excess noise factors compared to bulk and gain-bandwidth products greater than 200 GHz. The nanopillar optical antenna avalanche detector (NOAAD) architecture is utilized for spatially separating the absorption region from the avalanche region via the NOA resulting in single carrier injection without the use of a traditional SAM heterostructure. PMID:26627932

Continuous-wave infrared optical gain and amplified spontaneous emission at ultralow threshold by colloidal HgTe quantum dots.

PubMed

Geiregat, Pieter; Houtepen, Arjan J; Sagar, Laxmi Kishore; Infante, Ivan; Zapata, Felipe; Grigel, Valeriia; Allan, Guy; Delerue, Christophe; Van Thourhout, Dries; Hens, Zeger

2018-01-01

Colloidal quantum dots (QDs) raise more and more interest as solution-processable and tunable optical gain materials. However, especially for infrared active QDs, optical gain remains inefficient. Since stimulated emission involves multifold degenerate band-edge states, population inversion can be attained only at high pump power and must compete with efficient multi-exciton recombination. Here, we show that mercury telluride (HgTe) QDs exhibit size-tunable stimulated emission throughout the near-infrared telecom window at thresholds unmatched by any QD studied before. We attribute this unique behaviour to surface-localized states in the bandgap that turn HgTe QDs into 4-level systems. The resulting long-lived population inversion induces amplified spontaneous emission under continuous-wave optical pumping at power levels compatible with solar irradiation and direct current electrical pumping. These results introduce an alternative approach for low-threshold QD-based gain media based on intentional trap states that paves the way for solution-processed infrared QD lasers and amplifiers.

Continuous-wave infrared optical gain and amplified spontaneous emission at ultralow threshold by colloidal HgTe quantum dots

NASA Astrophysics Data System (ADS)

Geiregat, Pieter; Houtepen, Arjan J.; Sagar, Laxmi Kishore; Infante, Ivan; Zapata, Felipe; Grigel, Valeriia; Allan, Guy; Delerue, Christophe; van Thourhout, Dries; Hens, Zeger

2018-01-01

Colloidal quantum dots (QDs) raise more and more interest as solution-processable and tunable optical gain materials. However, especially for infrared active QDs, optical gain remains inefficient. Since stimulated emission involves multifold degenerate band-edge states, population inversion can be attained only at high pump power and must compete with efficient multi-exciton recombination. Here, we show that mercury telluride (HgTe) QDs exhibit size-tunable stimulated emission throughout the near-infrared telecom window at thresholds unmatched by any QD studied before. We attribute this unique behaviour to surface-localized states in the bandgap that turn HgTe QDs into 4-level systems. The resulting long-lived population inversion induces amplified spontaneous emission under continuous-wave optical pumping at power levels compatible with solar irradiation and direct current electrical pumping. These results introduce an alternative approach for low-threshold QD-based gain media based on intentional trap states that paves the way for solution-processed infrared QD lasers and amplifiers.

Properties of ambient cured blended alkali activated cement concrete

NASA Astrophysics Data System (ADS)

Talha Junaid, M.

2017-11-01

This paper presents results of the development and strength properties of ambient-cured alkali activated geopolymer concrete (GPC). The study looks at the strength properties, such as compressive strength, splitting tensile strength, and elastic modulus of such concretes and its dependency on various parameters. The parameters studied in this work are the type and proportions of pre-cursor materials, type of activator and their respective ratios and the curing time. Two types of pre-cursor material; low calcium fly ash (FA) and ground granulated blast furnace slag (GGBFS) were activated using different proportions of sodium silicate and sodium hydroxide solutions. The results indicate that ambient cured geopolymer concrete can be manufactured to match strength properties of ordinary Portland cement concrete (OPC). The strength properties of GPC are dependent on the type and ratio of activator and the proportion of GGBFS used. Increasing the percentage of GGBFS increased the compressive and tensile strengths, while reducing the setting time of the mix. The effect of GGBFS on strength was more pronounced in mixes that contained sodium silicate as activator solution. Unlike OPC, ambient-cured GPC containing sodium silicate gain most of their strength in the first 7 days and there is no change in strength thereafter. However, GPC mixes not containing sodium silicate only achieve a fraction of their strength at 7 days and extended curing is required for such concretes to gain full strength. The results also indicate that the elastic modulus values of GPC mixes without sodium silicate are comparable to OPC while mixes with sodium silicate have elastic modulus values much lower than ordinary concrete.

Research and Teaching: Use of Toulmin's Argumentation Scheme for Student Discourse to Gain Insight about Guided Inquiry Activities in College Chemistry

ERIC Educational Resources Information Center

Kulatunga, Ushiri; Moog, Richard S.; Lewis, Jennifer E.

2014-01-01

Although student production of arguments in group learning environments has been shown to promote scientific reasoning and understanding of science concepts, little previous work has examined the relationship of the structure of curricular materials to the production of argumentation. In this study, we examined this relationship for a collection…

Say It with Flowers! An fMRI Study of Object Mediated Communication

ERIC Educational Resources Information Center

Tylen, Kristian; Wallentin, Mikkel; Roepstorff, Andreas

2009-01-01

Human communicational interaction can be mediated by a host of expressive means from words in a natural language to gestures and material symbols. Given the proper contextual setting even an everyday object can gain a mediating function in a communicational situation. In this study we used event-related fMRI to study the brain activity caused by…

A novel source-drain follower for monolithic active pixel sensors

NASA Astrophysics Data System (ADS)

Gao, C.; Aglieri, G.; Hillemanns, H.; Huang, G.; Junique, A.; Keil, M.; Kim, D.; Kofarago, M.; Kugathasan, T.; Mager, M.; Marin Tobon, C. A.; Martinengo, P.; Mugnier, H.; Musa, L.; Lee, S.; Reidt, F.; Riedler, P.; Rousset, J.; Sielewicz, K. M.; Snoeys, W.; Sun, X.; Van Hoorne, J. W.; Yang, P.

2016-09-01

Monolithic active pixel sensors (MAPS) receive interest in tracking applications in high energy physics as they integrate sensor and readout electronics in one silicon die with potential for lower material budget and cost, and better performance. Source followers (SFs) are widely used for MAPS readout: they increase charge conversion gain 1/Ceff or decrease the effective sensing node capacitance Ceff because the follower action compensates part of the input capacitance. Charge conversion gain is critical for analog power consumption and therefore for material budget in tracking applications, and also has direct system impact. This paper presents a novel source-drain follower (SDF), where both source and drain follow the gate potential improving charge conversion gain. For the inner tracking system (ITS) upgrade of the ALICE experiment at CERN, low material budget is a primary requirement. The SDF circuit was studied as part of the effort to optimize the effective capacitance of the sensing node. The collection electrode, input transistor and routing metal all contribute to Ceff. Reverse sensor bias reduces the collection electrode capacitance. The novel SDF circuit eliminates the contribution of the input transistor to Ceff, reduces the routing contribution if additional shielding is introduced, provides a way to estimate the capacitance of the sensor itself, and has a voltage gain closer to unity than the standard SF. The SDF circuit has a somewhat larger area with a somewhat smaller bandwidth, but this is acceptable in most cases. A test chip, manufactured in a 180 nm CMOS image sensor process, implements small prototype pixel matrices in different flavors to compare the standard SF to the novel SF and to the novel SF with additional shielding. The effective sensing node capacitance was measured using a 55Fe source. Increasing reverse substrate bias from -1 V to -6 V reduces Ceff by 38% and the equivalent noise charge (ENC) by 22% for the standard SF. The SDF provides a further 9% improvement for Ceff and 25% for ENC. The SDF circuit with additional shielding provides 18% improvement for Ceff, and combined with -6 V reverse bias yields almost a factor 2.

Diode end pumped laser and harmonic generator using same

NASA Technical Reports Server (NTRS)

Byer, Robert L. (Inventor); Dixon, George J. (Inventor); Kane, Thomas J. (Inventor)

1988-01-01

A second harmonic, optical generator is disclosed in which a laser diode produces an output pumping beam which is focused by means of a graded, refractive index rod lens into a rod of lasant material, such as Nd:YAG, disposed within an optical resonator to pump the lasant material and to excite the optical resonator at a fundamental wavelength. A non-linear electro-optic material such as MgO:LiNbO.sub.3 is coupled to the excited, fundamental mode of the optical resonator to produce a non-linear interaction with the fundamental wavelength producing a harmonic. In one embodiment, the gain medium and the non-linear material are disposed within an optical resonator defined by a pair of reflectors, one of which is formed on a face of the gain medium and the second of which is formed on a face of the non-linear medium. In another embodiment, the non-linear, electro-optic material is doped with the lasant ion such that the gain medium and the non-linear doubling material are co-extensive in volume. In another embodiment, a non-linear, doubling material is disposed in an optical resonator external of the laser gai medium for improved stability of the second harmonic generation process. In another embodiment, the laser gain medium andthe non-linear material are bonded together by means of an optically transparent cement to form a mechanically stable, monolithic structure. In another embodiment, the non-linear material has reflective faces formed thereon to define a ring resonator to decouple reflections from the non-linear medium back to the gain medium for improved stability.

Electrochemical tuning of vertically aligned MoS2 nanofilms and its application in improving hydrogen evolution reaction

PubMed Central

Wang, Haotian; Lu, Zhiyi; Xu, Shicheng; Kong, Desheng; Cha, Judy J.; Zheng, Guangyuan; Hsu, Po-Chun; Yan, Kai; Bradshaw, David; Prinz, Fritz B.; Cui, Yi

2013-01-01

The ability to intercalate guest species into the van der Waals gap of 2D layered materials affords the opportunity to engineer the electronic structures for a variety of applications. Here we demonstrate the continuous tuning of layer vertically aligned MoS2 nanofilms through electrochemical intercalation of Li+ ions. By scanning the Li intercalation potential from high to low, we have gained control of multiple important material properties in a continuous manner, including tuning the oxidation state of Mo, the transition of semiconducting 2H to metallic 1T phase, and expanding the van der Waals gap until exfoliation. Using such nanofilms after different degree of Li intercalation, we show the significant improvement of the hydrogen evolution reaction activity. A strong correlation between such tunable material properties and hydrogen evolution reaction activity is established. This work provides an intriguing and effective approach on tuning electronic structures for optimizing the catalytic activity. PMID:24248362

Parasitic oscillation suppression in solid state lasers using optical coatings

DOEpatents

Honea, Eric C.; Beach, Raymond J.

2005-06-07

A laser gain medium having a layered coating on at least certain surfaces of the laser gain medium. The layered coating having a reflective inner material and an absorptive scattering outside material.

Obesity, Weight Gain and Risk of Colon Adenomas in Japanese Men

PubMed Central

Handa, Koichi; Hayabuchi, Hitomi; Kiyohara, Chikako; Inoue, Hisako; Marugame, Tomomi; Shinomiya, Sachiko; Hamada, Hiroaki; Onuma, Kazuya; Koga, Hiroko

1999-01-01

Obesity has been related to increased risk of colon cancer or adenomas, but the epidemiologic findings are not entirely consistent. We examined the relation of not only body mass index (BMI) but also waist‐to‐hip ratio (WHR) and weight gain to colon adenoma risk in men who received a preretirement health examination at the Japan Self Defense Forces (SDF) Fukuoka and Kumamoto Hospitals during the period from 995 to 1996. In the series of 803 men at age 47–55 years, 189 cases of colon adenomas and 226 controls with normal total colonoscopy were identified. Weight at 10 years before was ascertained by referring to the recorded data. After allowance for hospital, rank in the SDF, smoking and alcohol use, weight gain over the past 10 years was significantly associated with increased risk of colon adenomas (odds ratio for ≥ 6 kg versus ≤−2 kg = 2.2; 95% confidence interval 1.0–4.8). High BMI and high WHR were each associated with increased risk, but only WHR was related to the risk independently of weight gain. In particular, weight gain accompanied with a high WHR was associated with a significant increase in the risk. Men with high physical activity tended to have lower risk. Associations with obesity‐related variables and physical activity were not materially differential as regards the location and size of adenoma. The findings indicate that weight gain in middle age leading to abdominal obesity increases the risk of colon adenomas, and consequently of colon cancer. PMID:10543250

Increasing student learning through space life sciences education.

PubMed

Moreno, Nancy P; Roberts, J Kyle; Tharp, Barbara Z; Denk, James P; Cutler, Paula H; Thomson, William A

2005-01-01

Scientists and educators at Baylor College of Medicine are using space life sciences research areas as themes for middle school science and health instructional materials. This paper discusses study findings of the most recent unit, Food and Fitness, which teaches concepts related to energy and nutrition through guided inquiry. Results of a field test involving more than 750 students are reported. Use of the teaching materials resulted in significant knowledge gains by students as measured on a pre/post assessment administered by teachers. In addition, an analysis of the time spent by each teacher on each activity suggested that it is preferable to conduct all of the activities in the unit with students rather than allocating the same total amount of time on just a subset of the activities. c2005 Elsevier Ltd. All rights reserved.

Involving High School Students in Computational Physics University Research: Theory Calculations of Toluene Adsorbed on Graphene

PubMed Central

Borck, Øyvind; Gunnarsson, Linda; Lydmark, Pär

2016-01-01

To increase public awareness of theoretical materials physics, a small group of high school students is invited to participate actively in a current research projects at Chalmers University of Technology. The Chalmers research group explores methods for filtrating hazardous and otherwise unwanted molecules from drinking water, for example by adsorption in active carbon filters. In this project, the students use graphene as an idealized model for active carbon, and estimate the energy of adsorption of the methylbenzene toluene on graphene with the help of the atomic-scale calculational method density functional theory. In this process the students develop an insight into applied quantum physics, a topic usually not taught at this educational level, and gain some experience with a couple of state-of-the-art calculational tools in materials research. PMID:27505418

Involving High School Students in Computational Physics University Research: Theory Calculations of Toluene Adsorbed on Graphene.

PubMed

Ericsson, Jonas; Husmark, Teodor; Mathiesen, Christoffer; Sepahvand, Benjamin; Borck, Øyvind; Gunnarsson, Linda; Lydmark, Pär; Schröder, Elsebeth

2016-01-01

To increase public awareness of theoretical materials physics, a small group of high school students is invited to participate actively in a current research projects at Chalmers University of Technology. The Chalmers research group explores methods for filtrating hazardous and otherwise unwanted molecules from drinking water, for example by adsorption in active carbon filters. In this project, the students use graphene as an idealized model for active carbon, and estimate the energy of adsorption of the methylbenzene toluene on graphene with the help of the atomic-scale calculational method density functional theory. In this process the students develop an insight into applied quantum physics, a topic usually not taught at this educational level, and gain some experience with a couple of state-of-the-art calculational tools in materials research.

20 CFR 220.141 - Substantial gainful activity, defined.

Code of Federal Regulations, 2011 CFR

2011-04-01

...) Substantial work activity. Substantial work activity is work activity that involves doing significant physical... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false Substantial gainful activity, defined. 220... RETIREMENT ACT DETERMINING DISABILITY Substantial Gainful Activity § 220.141 Substantial gainful activity...

20 CFR 220.141 - Substantial gainful activity, defined.

Code of Federal Regulations, 2010 CFR

2010-04-01

...) Substantial work activity. Substantial work activity is work activity that involves doing significant physical... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Substantial gainful activity, defined. 220... RETIREMENT ACT DETERMINING DISABILITY Substantial Gainful Activity § 220.141 Substantial gainful activity...

An Experimental Test of Factors Attracting Deer Mice into Buildings.

PubMed

Kuenzi, Amy J; Douglass, Richard

2009-09-01

Deer mice (Peromyscus maniculatus) are the principal reservoir host of Sin Nombre virus (SNV). Deer mice use a wide variety of habitats including peridomestic settings in and around human dwellings, their presence in and around homes has been implicated as a risk factor for acquiring Hantavirus Pulmonary Syndrome. Deer mice are believed to enter buildings in order to gain access to a variety of resources including food, bedding material, and better thermal microclimates. However, no one has experimentally tested which factors influence mice use of buildings. We conducted experiments using small simulated buildings to determine the effects of two factors, i.e., food and bedding material, on mouse activity in these buildings. We also examined if these effects varied with time of year. We found that deer mice entered our buildings regardless of the presence or absence of food or bedding. However, the amount of activity in buildings was affected by what they contained. We found significantly higher indices of activity in buildings containing food compared to both empty buildings (control) and buildings containing bedding material. Time of year did not affect activity in buildings.

Experimental Data Extraction and in Silico Prediction of the Estrogenic Activity of Renewable Replacements for Bisphenol A

PubMed Central

Hong, Huixiao; Harvey, Benjamin G.; Palmese, Giuseppe R.; Stanzione, Joseph F.; Ng, Hui Wen; Sakkiah, Sugunadevi; Tong, Weida; Sadler, Joshua M.

2016-01-01

Bisphenol A (BPA) is a ubiquitous compound used in polymer manufacturing for a wide array of applications; however, increasing evidence has shown that BPA causes significant endocrine disruption and this has raised public concerns over safety and exposure limits. The use of renewable materials as polymer feedstocks provides an opportunity to develop replacement compounds for BPA that are sustainable and exhibit unique properties due to their diverse structures. As new bio-based materials are developed and tested, it is important to consider the impacts of both monomers and polymers on human health. Molecular docking simulations using the Estrogenic Activity Database in conjunction with the decision forest were performed as part of a two-tier in silico model to predict the activity of 29 bio-based platform chemicals in the estrogen receptor-α (ERα). Fifteen of the candidates were predicted as ER binders and fifteen as non-binders. Gaining insight into the estrogenic activity of the bio-based BPA replacements aids in the sustainable development of new polymeric materials. PMID:27420082

Mn-53 in the Apollo 15 and 16 drill stems - Evidence for surface mixing

NASA Technical Reports Server (NTRS)

Nishiizumi, K.; Imamura, M.; Honda, M.; Russ, G. P., III; Kohl, C. P.; Arnold, J. R.

1976-01-01

The activity of cosmic ray produced Mn-53 has been measured in a series of samples from the upper 10 cm of the Apollo 15 and 16 drill stems. The activity profiles for both cores indicate disturbance to depths of about 3 g/sq cm within the last 6 m.y. In at least one case (Apollo 16) the soil has been gardened to at least 14 g/sq cm within the last 10 m.y., and material from the upper less than 2 g/sq cm has been buried to 14 g/sq cm by this gardening. The results for the Apollo 15 core are compatible with a wide variety of possible histories including loss or gain of material.

Anti-diabetic activity of a mineraloid isolate, in vitro and in genetically diabetic mice.

PubMed

Deneau, Joel; Ahmed, Taufeeq; Blotsky, Roger; Bojanowski, Krzysztof

2011-01-01

Type II diabetes is a metabolic disease mediated through multiple molecular pathways. Here, we report anti-diabetic effect of a standardized isolate from a fossil material - a mineraloid leonardite - in in vitro tests and in genetically diabetic mice. The mineraloid isolate stimulated mitochondrial metabolism in human fibroblasts and this stimulation correlated with enhanced expression of genes coding for mitochondrial proteins such as ATP synthases and ribosomal protein precursors, as measured by DNA microarrays. In the diabetic animal model, consumption of the Totala isolate resulted in decreased weight gain, blood glucose, and glycated hemoglobin. To our best knowledge, this is the first description ever of a fossil material having anti-diabetic activity in pre-clinical models.

A Summary on Progress in Materials Development for Advanced Lithium-ion Cells for NASA's Exploration Missions

NASA Technical Reports Server (NTRS)

Reid, Concha M.

2011-01-01

Vehicles and stand-alone power systems that enable the next generation of human missions to the moon will require energy storage systems that are safer, lighter, and more compact than current state-of-the-art (SOA) aerospace quality lithium-ion (Li-ion) batteries. NASA is developing advanced Li-ion cells to enable or enhance future human missions to Near Earth Objects, such as asteroids, planets, moons, libration points, and orbiting structures. Advanced, high-performing materials are required to provide component-level performance that can offer the required gains at the integrated cell level. Although there is still a significant amount of work yet to be done, the present state of development activities has resulted in the synthesis of promising materials that approach the ultimate performance goals. This paper on interim progress of the development efforts will present performance of materials and cell components and will elaborate on the challenges of the development activities and proposed strategies to overcome technical issues.

Gain enhancement for wideband end-fire antenna design with artificial material.

PubMed

Wei, Min; Sun, Yuanhua; Wu, Xi; Wen, Wu

2016-01-01

Gain enhancement wideband end-fire antenna is proposed in this paper. The proposed antenna can achieve gain enhancement by loading novel artificial materials structures (Split-ring Resonators) in the end-fire direction while broad bandwidth is realized by using elliptic dipole elements and a microstrip to coplanar balun. The measurements show that the proposed antenna have around 5-8 dB gain in the working band (5-11 GHz), which is around 2 dB more than the unloaded one. This antenna can be used in target recognition systems for its advantages of end-fire radiation broad bandwidth and high gain.

Improvement of Students’ Environmental Literacy by Using Integrated Science Teaching Materials

NASA Astrophysics Data System (ADS)

Suryanti, D.; Sinaga, P.; Surakusumah, W.

2018-02-01

This study aims to determine the improvement of student environmental literacy through the use of integrated science teaching materials on pollution topics. The research is used weak experiment method with the one group pre-test post-test design. The sample of the study were junior high school students in Bandung amounted to 32 people of 7th grade. Data collection in the form of environmental literacy test instrument consist of four components of environmental literacy that is (1) Knowledge, (2) Competencies (Cognitive Skill), (3) Affective and (4) Environmentally Responsible Behavior. The results show that the student’s environmental literacy ability is improved after using integrated science teaching materials. An increase in the medium category is occurring in the knowledge (N-gain=46%) and cognitive skill (N-gain=31%), while the increase in the low category occurs in the affective component (N-gain=25%) and behaviour (N-gain=24%). The conclusions of this study as a whole the improvement of students’ environmental literacy by using integrated science teaching material is in the medium category (N-gain=34%).

20 CFR 404.1572 - What we mean by substantial gainful activity.

Code of Federal Regulations, 2011 CFR

2011-04-01

... work activity that involves doing significant physical or mental activities. Your work may be... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false What we mean by substantial gainful activity... Activity § 404.1572 What we mean by substantial gainful activity. Substantial gainful activity is work...

20 CFR 416.972 - What we mean by substantial gainful activity.

Code of Federal Regulations, 2011 CFR

2011-04-01

... work activity that involves doing significant physical or mental activities. Your work may be... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false What we mean by substantial gainful activity... Activity § 416.972 What we mean by substantial gainful activity. Substantial gainful activity is work...

20 CFR 416.972 - What we mean by substantial gainful activity.

Code of Federal Regulations, 2010 CFR

2010-04-01

... work activity that involves doing significant physical or mental activities. Your work may be... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false What we mean by substantial gainful activity... Activity § 416.972 What we mean by substantial gainful activity. Substantial gainful activity is work...

20 CFR 404.1572 - What we mean by substantial gainful activity.

Code of Federal Regulations, 2010 CFR

2010-04-01

... work activity that involves doing significant physical or mental activities. Your work may be... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false What we mean by substantial gainful activity... Activity § 404.1572 What we mean by substantial gainful activity. Substantial gainful activity is work...

Active metamaterial: Gain and stability, and microfluidic chip for THz cell spectroscopy

NASA Astrophysics Data System (ADS)

Tang, Qi

Metamaterials are artificially designed composite materials which can exhibit unique and unusual properties such as the negative refractive index, negative phase velocity, etc. The concept of metamaterials becomes prevalent in the electromagnetic society since the first experimental implementation in the early 2000s. Many fascinated potential applications, e.g. super lens, invisibility cloaking, and novel antennas that are electrically small, have been proposed based on metamaterials. However, most of the applications still remain in theory and are not suitable for practical applications mainly due to the intrinsic loss and narrow bandwidth (large dispersion) determined by the fundamental physics of metamaterials. In this dissertation, we incorporate active gain devices into conventional passive metamaterials to overcome loss and even provide gain. Two types of active gain negative refractive index metamaterials are proposed, designed and experimentally demonstrated, including an active composite left-/right-handed transmission line and an active volumetric metamaterial. In addition, we investigate the non-Foster circuits for broadband matching of electrically small antennas. A rigorous way of analyzing the stability of non-Foster circuits by normalized determinant function is proposed. We study the practical factors that may affect the stability of non-Foster circuits, including the device parasitics, DC biasing, layouts and load impedance. A stable floating negative capacitor is designed, fabricated and tested. Moreover, it is important to resolve the sign of refractive index for active gain media which can be quite challenging. We investigate the analytical solution of a gain slab system, and apply the Nyquist criterion to analyze the stability of a causal gain medium. We then emphasize that the result of frequency domain simulation has to be treated with care. Lastly, this dissertation discusses another interesting topic about THz spectroscopy of live cells. THz spectroscopy becomes an emerging technique for studying the dynamics and interactions of cells and biomolecules, but many practical challenges still remain in experimental studies. We present a prototype of simple and inexpensive cell-trapping microfluidic chip for THz spectroscopic study of live cells. Cells are transported, trapped and concentrated into the THz exposure region by applying an AC bias signal while the chip maintains a steady temperature at 37 ?C by resistive heating. We conduct some preliminary experiments on E. coli and T cell solution and compare the transmission spectra of empty channels, channels filled with aqueous media only, and channels filled with aqueous medium with un-concentrated and concentrated cells.

Efforts to Improve Mathematics Teacher Competency Through Training Program on Design Olympiad Mathematics Problems Based on Higher Order Thinking Skills in The Junior High School

NASA Astrophysics Data System (ADS)

Arnellis, A.; Jamaan, E. Z.; Amalita, N.

2018-04-01

The goal to analyse a improvement of teacher competence after being trained in preparing high-order math olympicad based on high order thinking skills in junior high school teachers in Pesisir Selatan Regency. The sample of these activities are teachers at the MGMP junior high school in Pesisir Selatan District. Evaluation of the implementation is done by giving a pre test and post test, which will measure the success rate of the implementation of this activities. The existence of the devotion activities is expected to understand the enrichment of mathematics olympiad material and training in the preparation of math olympiad questions for the teachers of South Pesisir district junior high school, motivating and raising the interest of the participants in order to follow the mathematics olympiad with the enrichment of mathematics materials and the training of problem solving about mathematics olympiad for junior high school teachers, the participants gain experience and gain insight, as well as the ins and outs of junior mathematics olympiad and implement to teachers and students in olympic competitions. The result of that the post-test is better than the result of pretest in the training of mathematics teacher competence improvement in composing the mathematics olympiad problem based on high order thinking skills of junior high school (SMP) in Pesisir Selatan District, West Sumatra, Indonesia.

Problem-Centered Supplemental Instruction in Biology: Influence on Content Recall, Content Understanding, and Problem Solving Ability

NASA Astrophysics Data System (ADS)

Gardner, Joel; Belland, Brian R.

2017-08-01

To address the need for effective, efficient ways to apply active learning in undergraduate biology courses, in this paper, we propose a problem-centered approach that utilizes supplemental web-based instructional materials based on principles of active learning. We compared two supplementary web-based modules using active learning strategies: the first used Merrill's First Principles of Instruction as a framework for organizing multiple active learning strategies; the second used a traditional web-based approach. Results indicated that (a) the First Principles group gained significantly from pretest to posttest at the Remember level ( t(40) = -1.432, p = 0.08, ES = 0.4) and at the Problem Solving level ( U = 142.5, N1 = 21, N2 = 21, p = .02, ES = 0.7) and (b) the Traditional group gained significantly from pretest to posttest at the Remember level ( t(36) = 1.762, p = 0.043, ES = 0.6). Those in the First Principles group were significantly more likely than the traditional group to be confident in their ability to solve problems in the future (χ2 (2, N = 40) = 3.585, p = 0.09).

Improved Student Learning through a Faculty Learning Community: How Faculty Collaboration Transformed a Large-Enrollment Course from Lecture to Student Centered

PubMed Central

Elliott, Emily R.; Reason, Robert D.; Coffman, Clark R.; Gangloff, Eric J.; Raker, Jeffrey R.; Powell-Coffman, Jo Anne; Ogilvie, Craig A.

2016-01-01

Undergraduate introductory biology courses are changing based on our growing understanding of how students learn and rapid scientific advancement in the biological sciences. At Iowa State University, faculty instructors are transforming a second-semester large-enrollment introductory biology course to include active learning within the lecture setting. To support this change, we set up a faculty learning community (FLC) in which instructors develop new pedagogies, adapt active-learning strategies to large courses, discuss challenges and progress, critique and revise classroom interventions, and share materials. We present data on how the collaborative work of the FLC led to increased implementation of active-learning strategies and a concurrent improvement in student learning. Interestingly, student learning gains correlate with the percentage of classroom time spent in active-learning modes. Furthermore, student attitudes toward learning biology are weakly positively correlated with these learning gains. At our institution, the FLC framework serves as an agent of iterative emergent change, resulting in the creation of a more student-centered course that better supports learning. PMID:27252298

Enhancing student retention of prerequisite knowledge through pre-class activities and in-class reinforcement.

PubMed

Taylor, Ann T S; Olofson, Eric L; Novak, Walter R P

2017-03-04

To foster the connection between biochemistry and the supporting prerequisite concepts, a collection of activities that explicitly link general and organic chemistry concepts to biochemistry ideas was written and either assigned as pre-class work or as recitation activities. We assessed student learning gains after using these activities alone, or in combination with regularly-integrated clicker and discussion questions. Learning gains were determined from student performance on pre- and post-tests covering key prerequisite concepts, biochemistry course exams, and student self-evaluation. Long-term retention of the material was assessed using a comprehensive exam given to a subset of the students. Our results show that using the pre-class exercises in combination with integrative questions was effective at improving student performance in both the short and long term. Similar results were obtained at both a large research institution with large class enrollments and at a private liberal arts college with moderate enrollments. © 2016 by The International Union of Biochemistry and Molecular Biology, 45(2):97-104, 2017. © 2016 The International Union of Biochemistry and Molecular Biology.

Tunable elastic parity-time symmetric structure based on the shunted piezoelectric materials

NASA Astrophysics Data System (ADS)

Hou, Zhilin; Assouar, Badreddine

2018-02-01

We theoretically and numerically report on the tunable elastic Parity-Time (PT) symmetric structure based on shunted piezoelectric units. We show that the elastic loss and gain can be archived in piezoelectric materials when they are shunted by external circuits containing positive and negative resistances. We present and discuss, as an example, the strongly dependent relationship between the exceptional points of a three-layered system and the impedance of their external shunted circuit. The achieved results evidence that the PT symmetric structures based on this proposed concept can actively be tuned without any change of their geometric configurations.

Microwave Synthesis and Characterization of Waste Soybean Oil-Based Gemini Imidazolinium Surfactants with Carbonate Linkage

NASA Astrophysics Data System (ADS)

Tripathy, Divya Bajpai; Mishra, Anuradha

Gemini surfactants are presently gaining attention due to their unusual self-assembling characteristics and incomparable interfacial activity. Current research work involves the cost-effective microwave (MW) synthesis of waste soybean oil-based gemini imidazolinium surfactants (GIS) having a carbonate linkage in its spacer moiety. Structural characterizations of the materials have been done using FT-IR, 1H-NMR and 13C-NMR. Using indigenous and natural material as base and MW as energy source for synthesizing the GIS with easily degradable chemical moiety make them to be labeled as green surfactants.

On Failure in Polycrystalline and Amorphous Brittle Materials

NASA Astrophysics Data System (ADS)

Bourne, N. K.

2009-12-01

The performance of behaviour of brittle materials depends upon discrete deformation mechanisms operating during the loading process. The critical mechanisms determining the behaviour of armour ceramics have not been isolated using traditional ballistics. It has recently become possible to measure strength histories in materials under shock. The data gained for the failed strength of the armour are shown to relate directly to the penetration measured into tiles. Further the material can be loaded and recovered for post-mortem examination. Failure is by micro-fracture that is a function of the defects and then cracking activated by plasticity mechanisms within the grains and failure at grain boundaries in the amorphous intergranular phase. Thus it is the shock-induced plastic yielding of grains at the impact face that determines the later time penetration through the tile.

Nanoporous Gold as a Platform for a Building Block Catalyst

DOE PAGES

Wittstock, Arne; Wichmann, Andre; Baeumer, Marcus

2012-09-25

The porous bulk materials are of great interest in catalysis because they can be employed in heterogeneous gas and liquid phase catalysis, electrocatalysis, and in electrocatalytic sensing. Nanoporous gold gained considerable attraction in this context because it is the prime example of a corrosion-derived nanoporous bulk metal. Moreover, the material was shown to be a very active and selective Au type catalyst for a variety of oxidation reactions. In leveraging the functionalization of the surface of the material with various additives, its catalytic applications can be extended and tuned. In this review, we will summarize recent developments in using nanoporousmore » gold as the platform for the development of high performance catalytic materials by adding metals, metal oxides, and molecular functionalities as building blocks.« less

The use of message framing to promote sexual risk reduction in young adolescents: a pilot exploratory study

PubMed Central

Camenga, Deepa R.; Hieftje, Kimberly D.; Fiellin, Lynn E.; Edelman, E. Jennifer; Rosenthal, Marjorie S.; Duncan, Lindsay R.

2014-01-01

Few studies have explored the application of message framing to promote health behaviors in adolescents. In this exploratory study, we examined young adolescents’ selection of gain- versus loss-framed images and messages when designing an HIV-prevention intervention to promote delayed sexual initiation. Twenty-six adolescents (aged 10–14 years) participated in six focus groups and created and discussed posters to persuade their peers to delay the initiation of sexual activity. Focus groups were audio-recorded and transcribed. A five-person multidisciplinary team analyzed the posters and focus group transcripts using thematic analysis. The majority of the posters (18/26, 69%) contained both gain- and loss-framed content. Of the 93/170 (56%) images and messages with framing, similar proportions were gain- (48/93, 52%) and loss-framed (45/93, 48%). Most gain-framed content (23/48, 48%) focused on academic achievement, whereas loss-framed content focused on pregnancy (20/45, 44%) and HIV/AIDS (14/45, 31%). These preliminary data suggest that young adolescents may prefer a combination of gain- and loss-framing in health materials to promote reduction in sexual risk behaviors. PMID:24452229

Multiwavelength Study of Powerful New Jet Activity in the Symbiotic Binary System R Aqr

NASA Astrophysics Data System (ADS)

Karovska, Margarita

2016-09-01

We propose to carry out coordinated high-spatial resolution Chandra ACIS-S and HST/WFC3 observations of R Aqr, a very active symbiotic interacting binary system. Our main goal is to study the physical characteristics of multi-scale components of the powerful jet; from near the central binary (within a few AU) to the jet-circumbinary material interaction region (2500 AU) and beyond , and especially of the recently discovered inner jet, to gain insight on early jet formation and propagation, such as jet kinematics and precession.

General and crevice corrosion study of the in-wall shielding materials for ITER vacuum vessel

NASA Astrophysics Data System (ADS)

Joshi, K. S.; Pathak, H. A.; Dayal, R. K.; Bafna, V. K.; Kimihiro, Ioki; Barabash, V.

2012-11-01

Vacuum vessel In-Wall Shield (IWS) will be inserted between the inner and outer shells of the ITER vacuum vessel. The behaviour of IWS in the vacuum vessel especially concerning the susceptibility to crevice of shielding block assemblies could cause rapid and extensive corrosion attacks. Even galvanic corrosion may be due to different metals in same electrolyte. IWS blocks are not accessible until life of the machine after closing of vacuum vessel. Hence, it is necessary to study the susceptibility of IWS materials to general corrosion and crevice corrosion under operations of ITER vacuum vessel. Corrosion properties of IWS materials were studied by using (i) Immersion technique and (ii) Electro-chemical Polarization techniques. All the sample materials were subjected to a series of examinations before and after immersion test, like Loss/Gain weight measurement, SEM analysis, and Optical stereo microscopy, measurement of surface profile and hardness of materials. After immersion test, SS 304B4 and SS 304B7 showed slight weight gain which indicate oxide layer formation on the surface of coupons. The SS 430 material showed negligible weight loss which indicates mild general corrosion effect. On visual observation with SEM and Metallography, all material showed pitting corrosion attack. All sample materials were subjected to series of measurements like Open Circuit potential, Cyclic polarization, Pitting potential, protection potential, Critical anodic current and SEM examination. All materials show pitting loop in OC2 operating condition. However, its absence in OC1 operating condition clearly indicates the activity of chloride ion to penetrate oxide layer on the sample surface, at higher temperature. The critical pitting temperature of all samples remains between 100° and 200°C.

Evolution of activities in international biological standardization since the early days of the Health Organisation of the League of Nations.

PubMed

Sizaret, P

1988-01-01

The main activities in international biological standardization during the 18 years that followed the first international biological standardization meeting in London in 1921 were concerned with expressing the potencies of test preparations in comparison with reference materials. After the Second World War, however, it became clear that the testing of biological substances against international reference materials was only one among several measures for obtaining safe and potent products. The activities in international biological standardization were therefore widened so that, by the strict observance of specific manufacturing and control requirements, it was possible to gain further in safety and efficacy. At the end of 1987, 42 international requirements for biological substances were available and were being used as national requirements, sometimes after minor modification, by the majority of WHO's Member States. This is of utmost importance for the worldwide use of safe and potent biological products, including vaccines.

Investigation of Material Gain of In0.90Ga0.10As0.59P0.41/InP Lasing Nano-Heregostructure

NASA Astrophysics Data System (ADS)

Yadav, Rashmi; Lal, Pyare; Rahman, F.; Dalela, S.; Alvi, P. A.

2014-02-01

In this paper, we have proposed a step separate confinement heterostructure (SCH) based lasing nano-heterostructure In0.90Ga0.10As0.59P0.41/InP consisting of single quantum well (SQW) and investigated material gain theoretically within TE and TM polarization modes. In addition, the quasi Fermi levels in the conduction and valence bands along with other lasing characteristics like anti-guiding factor, refractive index change with carrier density and differential gain have also been investigated and reported. Moreover, the behavior of quasi Fermi levels in respective bands has also been correlated with the material gain. Strain dependent study on material gain and refractive index change has also been reported. Interestingly, strain has been reported to play a very important role in shifting the lasing wavelength of TE mode to TM mode. The results investigated in the work suggest that the proposed unstrained nano-heterostructure is very suitable as a source for optical fiber based communication systems due to its lasing wavelengths achieved at 1.35 μm within TM mode, while 1.40 μm within TE mode.

Organic Micro/Nanoscale Lasers.

PubMed

Zhang, Wei; Yao, Jiannian; Zhao, Yong Sheng

2016-09-20

Micro/nanoscale lasers that can deliver intense coherent light signals at (sub)wavelength scale have recently captured broad research interest because of their potential applications ranging from on-chip information processing to high-throughput sensing. Organic molecular materials are a promising kind of ideal platform to construct high-performance microlasers, mainly because of their superiority in abundant excited-state processes with large active cross sections for high gain emissions and flexibly assembled structures for high-quality microcavities. In recent years, ever-increasing efforts have been dedicated to developing such organic microlasers toward low threshold, multicolor output, broadband tunability, and easy integration. Therefore, it is increasingly important to summarize this research field and give deep insight into the structure-property relationships of organic microlasers to accelerate the future development. In this Account, we will review the recent advances in organic miniaturized lasers, with an emphasis on tunable laser performances based on the tailorable microcavity structures and controlled excited-state gain processes of organic materials toward integrated photonic applications. Organic π-conjugated molecules with weak intermolecular interactions readily assemble into regular nanostructures that can serve as high-quality optical microcavities for the strong confinement of photons. On the basis of rational material design, a series of optical microcavities with different structures have been controllably synthesized. These microcavity nanostructures can be endowed with effective four-level dynamic gain processes, such as excited-state intramolecular charge transfer, excited-state intramolecular proton transfer, and excimer processes, that exhibit large dipole optical transitions for strongly active gain behaviors. By tailoring these excited-state processes with molecular/crystal engineering and external stimuli, people have effectively modulated the performances of organic micro/nanolasers. Furthermore, by means of controlled assembly and tunable laser performances, efficient outcoupling of microlasers has been successfully achieved in various organic hybrid microstructures, showing considerable potential for the integrated photonic applications. This Account starts by presenting an overview of the research evolution of organic microlasers in terms of microcavity resonators and energy-level gain. Then a series of strategies to tailor the microcavity structures and excited-state dynamics of organic nanomaterials for the modulation of lasing performances are highlighted. In the following part, we introduce the construction and advanced photonic functionalities of organic-microlaser-based hybrid structures and their applications in integrated nanophotonics. Finally, we provide our outlook on the current challenges as well as the future development of organic microlasers. It is anticipated that this Account will provide inspiration for the development of miniaturized lasers with desired performances by tailoring of excited-state processes and microcavity structures toward integrated photonic applications.

Activating lay health influencers to promote tobacco cessation.

PubMed

Muramoto, Myra L; Hall, John R; Nichter, Mark; Nichter, Mimi; Aickin, Mikel; Connolly, Tim; Matthews, Eva; Campbell, Jean Z; Lando, Harry A

2014-05-01

To evaluate the effect of tobacco cessation brief-intervention (BI) training for lay "health influencers," on knowledge, self-efficacy and the proportion of participants reporting BI delivery post-training. Randomized, community-based study comparing In-person or Web-based training, with mailed materials. In-person and Web-training groups had significant post-training cessation knowledge and self-efficacy gains. All groups increased the proportion of individuals reporting BIs at follow-up, with no significant between-group differences. Irrespective of participants' prior intervention experience, 80%-86% reported BIs within the past 90 days; 71%-79% reported >1 in the past 30. Web and In-person training significantly increase health influencer cessation knowledge and self-efficacy. With minimal prompting and materials, even persons without BI experience can be activated to encourage tobacco cessation.

Workshop Results: Teaching Geoscience to K-12 Teachers

NASA Astrophysics Data System (ADS)

Nahm, A.; Villalobos, J. I.; White, J.; Smith-Konter, B. R.

2012-12-01

A workshop for high school and middle school Earth and Space Science (ESS) teachers was held this summer (2012) as part of an ongoing collaboration between the University of Texas at El Paso (UTEP) and El Paso Community College (EPCC) Departments of Geological Sciences. This collaborative effort aims to build local Earth science literacy and educational support for the geosciences. Sixteen teachers from three school districts from El Paso and southern New Mexico area participated in the workshop, consisting of middle school, high school, early college high school, and dual credit faculty. The majority of the teachers had little to no experience teaching geoscience, thus this workshop provided an introduction to basic geologic concepts to teachers with broad backgrounds, which will result in the introduction of geoscience to many new students each year. The workshop's goal was to provide hands-on activities illustrating basic geologic and scientific concepts currently used in introductory geology labs/lectures at both EPCC and UTEP to help engage pre-college students. Activities chosen for the workshop were an introduction to Google Earth for use in the classroom, relative age dating and stratigraphy using volcanoes, plate tectonics utilizing the jigsaw pedagogy, and the scientific method as a think-pair-share activity. All activities where designed to be low cost and materials were provided for instructors to take back to their institutions. A list of online resources for teaching materials was also distributed. Before each activity, a short pre-test was given to the participants to gauge their level of knowledge on the subjects. At the end of the workshop, participants were given a post-test, which tested the knowledge gain made by participating in the workshop. In all cases, more correct answers were chosen in the post-test than the individual activity pre-tests, indicating that knowledge of the subjects was gained. The participants enjoyed participating in these activities and intend to use them in their classes in the future. Copies of the materials used in this workshop are available upon request.

Learning Physical Science through Astronomy Activities: A Comparison between Constructivist and Traditional Approaches in Grades 3-6

NASA Astrophysics Data System (ADS)

Ward, R. Bruce; Sadler, Philip M.; Shapiro, Irwin I.

We report on an evaluation of the effectiveness of Project ARIES, an astronomy- based physical science curriculum for upper elementary and middle school children. ARIES students use innovative, simple, and affordable apparatus to carry out a wide range of indoor and outdoor hands-on, discovery- based activities. Student journals and comprehensive teacher materials aid in making the science content accessible to students based on their shared experiences and observations. Approximately 750 Grades 3 6 students in ARIES (or treatment) classrooms are compared with approximately 650 Grades 4 6 students in control classrooms through a series of open-ended assessment measures, using a pretest and posttest format. A detailed analysis by item measures the gain in treatment and control groups. We identify concepts where the ARIES approach is more effective, where both are equally effective, and where neither results in much learning. (The ARIES approach was never less effective.) Although learning is in evidence for both control and treatment groups, overall, the ARIES students achieve roughly four times the gain of their control counterparts. In particular, ARIES students had much greater gains for the concepts that the control students found most difficult.

Material gain engineering in GeSn/Ge quantum wells integrated with an Si platform

NASA Astrophysics Data System (ADS)

Mączko, H. S.; Kudrawiec, R.; Gladysiewicz, M.

2016-09-01

It is shown that compressively strained Ge1-xSnx/Ge quantum wells (QWs) grown on a Ge substrate with 0.1 ≤ x ≤ 0.2 and width of 8 nm ≤ d ≤ 14 nm are a very promising gain medium for lasers integrated with an Si platform. Such QWs are type-I QWs with a direct bandgap and positive transverse electric mode of material gain, i.e. the modal gain. The electronic band structure near the center of Brillouin zone has been calculated for various Ge1-xSnx/Ge QWs with use of the 8-band kp Hamiltonian. To calculate the material gain for these QWs, occupation of the L valley in Ge barriers has been taken into account. It is clearly shown that this occupation has a lot of influence on the material gain in the QWs with low Sn concentrations (Sn < 15%) and is less important for QWs with larger Sn concentration (Sn > 15%). However, for QWs with Sn > 20% the critical thickness of a GeSn layer deposited on a Ge substrate starts to play an important role. Reduction in the QW width shifts up the ground electron subband in the QW and increases occupation of the L valley in the barriers instead of the Γ valley in the QW region.

Learn before Lecture: A Strategy That Improves Learning Outcomes in a Large Introductory Biology Class

PubMed Central

Moravec, Marin; Williams, Adrienne; Aguilar-Roca, Nancy

2010-01-01

Actively engaging students in lecture has been shown to increase learning gains. To create time for active learning without displacing content we used two strategies for introducing material before class in a large introductory biology course. Four to five slides from 2007/8 were removed from each of three lectures in 2009 and the information introduced in preclass worksheets or narrated PowerPoint videos. In class, time created by shifting lecture material to learn before lecture (LBL) assignments was used to engage students in application of their new knowledge. Learning was evaluated by comparing student performance in 2009 versus 2007/8 on LBL-related question pairs, matched by level and format. The percentage of students who correctly answered five of six LBL-related exam questions was significantly higher (p < 0.001) in 2009 versus 2007/8. The mean increase in performance was 21% across the six LBL-related questions compared with <3% on all non-LBL exam questions. The worksheet and video LBL formats were equally effective based on a cross-over experimental design. These results demonstrate that LBLs combined with interactive exercises can be implemented incrementally and result in significant increases in learning gains in large introductory biology classes. PMID:21123694

Improved actuation strain of PDMS-based DEA materials chemically modified with softening agents

NASA Astrophysics Data System (ADS)

Biedermann, Miriam; Blümke, Martin; Wegener, Michael; Krüger, Hartmut

2015-04-01

Dielectric elastomer actuators (DEAs) are smart materials that gained much in interest particularly in recent years. One active field of research is the improvement of their properties by modification of their structural framework. The object of this work is to improve the actuation properties of polydimethylsiloxane (PDMS)-based DEAs by covalent incorporation of mono-vinyl-terminated low-molecular PDMS chains into the PDMS network. These low-molecular units act as a kind of softener within the PDMS network. The loose chain ends interfere with the network formation and lower the network's density. PDMS films with up to 50wt% of low-molecular PDMS additives were manufactured and the chemical, mechanical, electrical, and electromechanical properties of these novel materials were investigated.

20 CFR 416.910 - Meaning of substantial gainful activity.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Meaning of substantial gainful activity. 416....910 Meaning of substantial gainful activity. Substantial gainful activity means work that— (a) Involves doing significant and productive physical or mental duties; and (b) Is done (or intended) for pay...

20 CFR 404.1510 - Meaning of substantial gainful activity.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Meaning of substantial gainful activity. 404... Meaning of substantial gainful activity. Substantial gainful activity means work that— (a) Involves doing significant and productive physical or mental duties; and (b) Is done (or intended) for pay or profit. (See...

20 CFR 220.140 - General.

Code of Federal Regulations, 2011 CFR

2011-04-01

... substantial gainful activity level. If the claimant is able to engage in substantial gainful activity, the... Substantial Gainful Activity § 220.140 General. The work that a claimant has done during any period in which... Retirement Act. Even if the work the claimant has done was not substantial gainful activity, it may show that...

20 CFR 220.140 - General.

Code of Federal Regulations, 2010 CFR

2010-04-01

... substantial gainful activity level. If the claimant is able to engage in substantial gainful activity, the... Substantial Gainful Activity § 220.140 General. The work that a claimant has done during any period in which... Retirement Act. Even if the work the claimant has done was not substantial gainful activity, it may show that...

20 CFR 416.910 - Meaning of substantial gainful activity.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Meaning of substantial gainful activity. 416....910 Meaning of substantial gainful activity. Substantial gainful activity means work that— (a) Involves doing significant and productive physical or mental duties; and (b) Is done (or intended) for pay...

20 CFR 404.1510 - Meaning of substantial gainful activity.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Meaning of substantial gainful activity. 404... Meaning of substantial gainful activity. Substantial gainful activity means work that— (a) Involves doing significant and productive physical or mental duties; and (b) Is done (or intended) for pay or profit. (See...

Measuring Conceptual Gains and Benefits of Student Problem Designs

NASA Astrophysics Data System (ADS)

Mandell, Eric; Snyder, Rachel; Oswald, Wayne

2011-10-01

Writing assignments can be an effective way of getting students to practice higher-order learning skills in physics. One example of such an assignment is that of problem design. One version of the problem design assignment asks the student to evaluate the material from a chapter, after all instruction and other activities are complete. The student is to decide what concepts and ideas are most central, or critical in the chapter, and construct a problem that he or she feels best encompasses the major themes. Here, we use two concept surveys (FCI and EMCS) to measure conceptual gains for students completing the problem design assignment and present the preliminary results, comparing across several categories including gender, age, degree program, and class standing.

Optimum Installation of Sorptive Building Materials Using Contribution Ratio of Pollution Source for Improvement of Indoor Air Quality.

PubMed

Park, Seonghyun; Seo, Janghoo

2016-04-01

Reinforcing the insulation and airtightness of buildings and the use of building materials containing new chemical substances have caused indoor air quality problems. Use of sorptive building materials along with removal of pollutants, constant ventilation, bake-out, etc. are gaining attention in Korea and Japan as methods for improving such indoor air quality problems. On the other hand, sorptive building materials are considered a passive method of reducing the concentration of pollutants, and their application should be reviewed in the early stages. Thus, in this research, activated carbon was prepared as a sorptive building material. Then, computational fluid dynamics (CFD) was conducted, and a method for optimal installation of sorptive building materials was derived according to the indoor environment using the contribution ratio of pollution source (CRP) index. The results show that a method for optimal installation of sorptive building materials can be derived by predicting the contribution ratio of pollutant sources according to the CRP index.

Nuclear Forensic Science: Analysis of Nuclear Material Out of Regulatory Control

NASA Astrophysics Data System (ADS)

Kristo, Michael J.; Gaffney, Amy M.; Marks, Naomi; Knight, Kim; Cassata, William S.; Hutcheon, Ian D.

2016-06-01

Nuclear forensic science seeks to identify the origin of nuclear materials found outside regulatory control. It is increasingly recognized as an integral part of a robust nuclear security program. This review highlights areas of active, evolving research in nuclear forensics, with a focus on analytical techniques commonly employed in Earth and planetary sciences. Applications of nuclear forensics to uranium ore concentrates (UOCs) are discussed first. UOCs have become an attractive target for nuclear forensic researchers because of the richness in impurities compared to materials produced later in the fuel cycle. The development of chronometric methods for age dating nuclear materials is then discussed, with an emphasis on improvements in accuracy that have been gained from measurements of multiple radioisotopic systems. Finally, papers that report on casework are reviewed, to provide a window into current scientific practice.

Modeling and control of active twist aircraft

NASA Astrophysics Data System (ADS)

Cramer, Nicholas Bryan

The Wright Brothers marked the beginning of powered flight in 1903 using an active twist mechanism as their means of controlling roll. As time passed due to advances in other technologies that transformed aviation the active twist mechanism was no longer used. With the recent advances in material science and manufacturability, the possibility of the practical use of active twist technologies has emerged. In this dissertation, the advantages and disadvantages of active twist techniques are investigated through the development of an aeroelastic modeling method intended for informing the designs of such technologies and wind tunnel testing to confirm the capabilities of the active twist technologies and validate the model. Control principles for the enabling structural technologies are also proposed while the potential gains of dynamic, active twist are analyzed.

Oxidation Resistance of Materials Based on Ti3AlC2 Nanolaminate at 600 °C in Air

NASA Astrophysics Data System (ADS)

Ivasyshyn, Andrij; Ostash, Orest; Prikhna, Tatiana; Podhurska, Viktoriya; Basyuk, Tatiana

2016-08-01

The oxidation behavior of Ti3AlC2-based materials had been investigated at 600 °C in static air for 1000 h. It was shown that the intense increase of weight gain per unit surface area for sintered material with porosity of 22 % attributed to oxidation of the outer surface of the specimen and surfaces of pores in the bulk material. The oxidation kinetics of the hot-pressed Ti3AlC2-based material with 1 % porosity remarkably increased for the first 15 h and then slowly decreased. The weight gain per unit surface area for this material was 1.0 mg/cm2 after exposition for 1000 h. The intense initial oxidation of Ti3AlC2-based materials can be eliminated by pre-oxidation treatment at 1200 °C in air for 2 h. As a result, the weight gain per unit surface area for the pre-oxidized material did not exceed 0.11 mg/cm2 after 1000 h of exposition at 600 °C in air. It was demonstrated that the oxidation resistance of Ti3AlC2-based materials can be significantly improved by niobium addition.

Gain and energy storage in holmium YLF

NASA Technical Reports Server (NTRS)

Storm, Mark E.; Deyst, John P.

1991-01-01

It is demonstrated that Q-switched holmium lasers are capable of high-gain and high-energy operation at 300 K. Small-signal gain coefficients of 0.50 and 0.12/cm have been measured in YLF and YAG, respectively. Small-signal gains of 0.50/cm are comparable to those achievable in Nd:YAG and are not typical of low-gain materials. This large gain in the Ho:YLF material is made possible by operating the amplifier in the ground state depletion mode. The amplifier performance data and associated analysis presented demonstrate that efficient energy storage is possible with very high excited state ion densities of the Ho 5I7 upper laser level. This is an important result since upconversion can limit the 5I7 population. Although upconversion was still present in this experiment, it was possible to achieve efficient energy storage, demonstrating that the problem is manageable even at high excitation densities in YLF.

Recent development of nano-materials used in DNA biosensors.

PubMed

Xu, Kai; Huang, Junran; Ye, Zunzhong; Ying, Yibin; Li, Yanbin

2009-01-01

As knowledge of the structure and function of nucleic acid molecules has increased, sequence-specific DNA detection has gained increased importance. DNA biosensors based on nucleic acid hybridization have been actively developed because of their specificity, speed, portability, and low cost. Recently, there has been considerable interest in using nano-materials for DNA biosensors. Because of their high surface-to-volume ratios and excellent biological compatibilities, nano-materials could be used to increase the amount of DNA immobilization; moreover, DNA bound to nano-materials can maintain its biological activity. Alternatively, signal amplification by labeling a targeted analyte with nano-materials has also been reported for DNA biosensors in many papers. This review summarizes the applications of various nano-materials for DNA biosensors during past five years. We found that nano-materials of small sizes were advantageous as substrates for DNA attachment or as labels for signal amplification; and use of two or more types of nano-materials in the biosensors could improve their overall quality and to overcome the deficiencies of the individual nano-components. Most current DNA biosensors require the use of polymerase chain reaction (PCR) in their protocols. However, further development of nano-materials with smaller size and/or with improved biological and chemical properties would substantially enhance the accuracy, selectivity and sensitivity of DNA biosensors. Thus, DNA biosensors without PCR amplification may become a reality in the foreseeable future.

Recent Development of Nano-Materials Used in DNA Biosensors

PubMed Central

Xu, Kai; Huang, Junran; Ye, Zunzhong; Ying, Yibin; Li, Yanbin

2009-01-01

As knowledge of the structure and function of nucleic acid molecules has increased, sequence-specific DNA detection has gained increased importance. DNA biosensors based on nucleic acid hybridization have been actively developed because of their specificity, speed, portability, and low cost. Recently, there has been considerable interest in using nano-materials for DNA biosensors. Because of their high surface-to-volume ratios and excellent biological compatibilities, nano-materials could be used to increase the amount of DNA immobilization; moreover, DNA bound to nano-materials can maintain its biological activity. Alternatively, signal amplification by labeling a targeted analyte with nano-materials has also been reported for DNA biosensors in many papers. This review summarizes the applications of various nano-materials for DNA biosensors during past five years. We found that nano-materials of small sizes were advantageous as substrates for DNA attachment or as labels for signal amplification; and use of two or more types of nano-materials in the biosensors could improve their overall quality and to overcome the deficiencies of the individual nano-components. Most current DNA biosensors require the use of polymerase chain reaction (PCR) in their protocols. However, further development of nano-materials with smaller size and/or with improved biological and chemical properties would substantially enhance the accuracy, selectivity and sensitivity of DNA biosensors. Thus, DNA biosensors without PCR amplification may become a reality in the foreseeable future. PMID:22346713

NASA Applications of Molecular Nanotechnology

NASA Technical Reports Server (NTRS)

Globus, Al; Bailey, David; Han, Jie; Jaffe, Richard; Levit, Creon; Merkle, Ralph; Srivastava, Deepak

1998-01-01

Laboratories throughout the world are rapidly gaining atomically precise control over matter. As this control extends to an ever wider variety of materials, processes and devices, opportunities for applications relevant to NASA's missions will be created. This document surveys a number of future molecular nanotechnology capabilities of aerospace interest. Computer applications, launch vehicle improvements, and active materials appear to be of particular interest. We also list a number of applications for each of NASA's enterprises. If advanced molecular nanotechnology can be developed, almost all of NASA's endeavors will be radically improved. In particular, a sufficiently advanced molecular nanotechnology can arguably bring large scale space colonization within our grasp.

Metal nanoparticles in DBS card materials modification

NASA Astrophysics Data System (ADS)

Metelkin, A.; Frolov, G.; Kuznetsov, D.; Kolesnikov, E.; Chuprunov, K.; Kondakov, S.; Osipov, A.; Samsonova, J.

2015-11-01

In the recent years the method of collecting and storing Dried Blood Spots (DBS) on special cellulose membrane (paper) has gained wide popularity. But possible damage of biosamples caused by microorganisms in case of their incomplete drying is a disadvantage of the method. It can be overcome by treating sample-collection membranes with colloidal solutions of metal nanoparticles, having antibacterial effect. The team studied antibacterial properties of nonwoven material samples with various coatings (alcohol sols of copper, aluminium, iron, titanium, silver and vanadium nanoparticles). Colloidal solutions of nanoparticles were obtained by means of electroerosion method with further low-temperature plasma condensation. Antibacterial activity of fiberglass and cellulose membrane samples with nanoparticle coatings was studied using B. cereus and plaque bacteria cultures. It was revealed that nanostructured coatings can suppress bacterial activity; in addition they can diffuse from the membrane surface into medium which leads to widening the areas of inhibiting testing cultures’ growth. Thus, membrane materials treatment with alcohol-sols of metal nanoparticles can be seen as promising for conferring antibacterial properties to DBS carriers.

GAIN Technology Workshops Summary Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braase, Lori Ann

National and global demand for nuclear energy is increasing and United States (U.S.) global leadership is eroding. There is a sense of urgency with respect to the deployment of the innovative nuclear energy technologies. The Gateway for Accelerated Innovation in Nuclear (GAIN) initiative is based on the simultaneous achievement of three strategic goals. The first is maintaining global technology leadership within the U.S. Department of Energy (DOE). The second is enabling global industrial leadership for nuclear vendors and suppliers. The third is focused on utility optimization of nuclear energy within the clean energy portfolio. An effective public-private partnership is requiredmore » to achieve these goals. DOEs recognizes the recent sense of urgency new developers and investors have in getting their concepts to market. They know that time to market for nuclear technology takes too long and the facilities needed to conduct the necessary research, development and demonstration (RD&D) activities are very expensive to develop and maintain. Early technologies, in the lower technology readiness levels (TRL) need materials testing, analysis, modeling, code development, etc., most of which currently exists in the DOE national laboratory system. However, mature technologies typically need large component testing and demonstration facilities, which are expensive and long-lead efforts. By understanding the needs of advanced nuclear technology developers, GAIN will connect DOE national laboratory capabilities (e.g., facilities, expertise, materials, and data) with industry RD&D needs. In addition, GAIN is working with the Nuclear Regulatory Commission (NRC) to streamline processes and increase understanding of the licensing requirements for advanced reactors.« less

Crestal Approach to Sinus Floor Elevation for Atrophic Maxilla Using Platelet-Rich Fibrin as the Only Grafting Material: A 1-Year Prospective Study.

PubMed

Kanayama, Takeo; Horii, Koichiro; Senga, Yasuko; Shibuya, Yasuyuki

2016-02-01

Platelet-rich fibrin (PRF) has been recently used as the sole grafting material in sinus floor elevation procedures. The aim of this prospective study was to measure the bone gain around the dental implant after using the crestal approach to sinus floor elevation using platelet-rich fibrin as the only grafting material in atrophic posterior maxillae with residual bone height <5 mm. Two different types of implants were used: hydroxyapatite (HA) and sandblasted acid-etched (SA) implants. Panoramic radiography and computed tomography were used to measure the endosinus bone gain. Twenty-seven patients with 39 implants (19 HA and 20 SA) were included in this study. The mean residual bone measurements before surgery in the SA and HA groups were 2.85 and 2.68 mm, respectively. The mean average bone gains for 1 year in the SA and HA groups were 4.38 and 4.00 mm, respectively. This prospective study showed that platelet-rich fibrin promoted endosinus bone gain when used as the grafting material in the crestal approach to sinus floor elevation.

Integration of Quantum Cascade Lasers and Passive Waveguides

DTIC Science & Technology

2015-06-01

Optics, 2005. (CLEO). Conference on , Vol. 2 (2005) pp. 863–865. 2J. Montoya , A. Sanchez-Rubio, R. Hatch, and H . Payson, Appl. Opt. 53, 7551 (2014...Integration of Quantum Cascade Lasers and Passive Waveguidesa) Juan Montoya ,1, b) Christine Wang,1 Anish Goyal,1 Kevin Creedon,1 Michael Connors,1...active sec- tion quantum cascade laser material is biased to achieve gain. Proton ( H +) implantation reduces the free-carrier con- centration and

High Power Mid Wave Infrared Semiconductor Lasers

DTIC Science & Technology

2006-06-15

resonance and the gain spectrum. The devices were grown using solid source molecular beam epitaxy (MBE) in a V80 reactor. Two side polished, undoped...verify the inherent low activation energy. N-type and P-type AISb, and various compositions of InxAl 1xSb, were grown by solid-source molecular beam ...level monitoring. Advances in epitaxial growth of semiconductor materials have allowed the development of Arsenic- free optically-pumped MWIR lasers on

8-band and 14-band kp modeling of electronic band structure and material gain in Ga(In)AsBi quantum wells grown on GaAs and InP substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gladysiewicz, M.; Wartak, M. S.; Department of Physics and Computer Science, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5

The electronic band structure and material gain have been calculated for GaAsBi/GaAs quantum wells (QWs) with various bismuth concentrations (Bi ≤ 15%) within the 8-band and 14-band kp models. The 14-band kp model was obtained by extending the standard 8-band kp Hamiltonian by the valence band anticrossing (VBAC) Hamiltonian, which is widely used to describe Bi-related changes in the electronic band structure of dilute bismides. It has been shown that in the range of low carrier concentrations n < 5 × 10{sup 18 }cm{sup −3}, material gain spectra calculated within 8- and 14-band kp Hamiltonians are similar. It means that the 8-band kp model can be usedmore » to calculate material gain in dilute bismides QWs. Therefore, it can be applied to analyze QWs containing new dilute bismides for which the VBAC parameters are unknown. Thus, the energy gap and electron effective mass for Bi-containing materials are used instead of VBAC parameters. The electronic band structure and material gain have been calculated for 8 nm wide GaInAsBi QWs on GaAs and InP substrates with various compositions. In these QWs, Bi concentration was varied from 0% to 5% and indium concentration was tuned in order to keep the same compressive strain (ε = 2%) in QW region. For GaInAsBi/GaAs QW with 5% Bi, gain peak was determined to be at about 1.5 μm. It means that it can be possible to achieve emission at telecommunication windows (i.e., 1.3 μm and 1.55 μm) for GaAs-based lasers containing GaInAsBi/GaAs QWs. For GaInAsBi/Ga{sub 0.47}In{sub 0.53}As/InP QWs with 5% Bi, gain peak is predicted to be at about 4.0 μm, i.e., at the wavelengths that are not available in current InP-based lasers.« less

Activating Lay Health Influencers to Promote Tobacco Cessation

PubMed Central

Muramoto, Myra L.; Hall, John R.; Nichter, Mark; Nichter, Mimi; Aickin, Mikel; Connolly, Tim; Matthews, Eva; Campbell, Jean Z.; Lando, Harry A.

2014-01-01

Objective Evaluate the effect of tobacco cessation brief-intervention (BI) training for lay “health influencers,” on knowledge, self-efficacy and the proportion of participants reporting BI delivery post-training. Methods Randomized, community-based study comparing In-person or Web-based training, with mailed materials. Results In-person and Web-training groups had significant post-training cessation knowledge and self-efficacy gains. All groups increased the proportion of individuals reporting BIs at follow-up, with no significant between-group differences. Irrespective of participants’ prior intervention experience, 80–86% reported BIs within the past 90 days; 71–79% reported ≥1 in the past 30. Conclusions Web and In-person training significantly increase health influencer cessation knowledge and self-efficacy. With minimal prompting and materials, even persons without BI experience can be activated to encourage tobacco cessation. PMID:24636035

Integration of quantum cascade lasers and passive waveguides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montoya, Juan, E-mail: juan.montoya@ll.mit.edu; Wang, Christine; Goyal, Anish

2015-07-20

We report on monolithic integration of active quantum cascade laser (QCL) materials with passive waveguides formed by using proton implantation. Proton implantation reduces the electron concentration in the QCL layers by creating deep levels that trap carriers. This strongly reduces the intersubband absorption and the free-carrier absorption in the gain region and surrounding layers, thus significantly reducing optical loss. We have measured loss as low as α = 0.33 cm{sup −1} in λ = 9.6 μm wavelength proton-implanted QCL material. We have also demonstrated lasing in active-passive integrated waveguides. This simple integration technique is anticipated to enable low-cost fabrication in infrared photonic integrated circuits in themore » mid-infrared (λ ∼ 3–16 μm)« less

Nanostructured p-type semiconducting transparent oxides: promising materials for nano-active devices and the emerging field of "transparent nanoelectronics".

PubMed

Banerjee, Arghya; Chattopadhyay, Kalyan K

2008-01-01

Transparent conducting oxides (TCO) with p-type semiconductivity have recently gained renewed interest for the fabrication of all-oxide transparent junctions, having potential applications in the emerging field of 'Transparent' or 'Invisible Electronics'. This kind of transparent junctions can be used as a "functional" window, which will transmit visible portion of solar radiation, but generates electricity by the absorption of the UV part. Therefore, these devices can be used as UV shield as well as UV cells. In this report, a brief review on the research activities on various p-TCO materials is furnished along-with the fabrication of different transparent p-n homojunction, heterojunction and field-effect transistors. Also the reason behind the difficulties in obtaining p-TCO materials and possible solutions are discussed in details. Considerable attention is given in describing the various patent generations on the field of p-TCO materials as well as transparent p-n junction diodes and light emitting devices. Also, most importantly, a detailed review and patenting activities on the nanocrystalline p-TCO materials and transparent nano-active device fabrication are furnished with considerable attention. And finally, a systematic description on the fabrication and characterization of nanocrystalline, p-type transparent conducting CuAlO(2) thin film, deposited by cost-effective low-temperature DC sputtering technique, by our group, is furnished in details. These p-TCO micro/nano-materials have wide range of applications in the field of optoelectronics, nanoelectronics, space sciences, field-emission displays, thermoelectric converters and sensing devices.

Prevalence of human cell material: DNA and RNA profiling of public and private objects and after activity scenarios.

PubMed

van den Berge, M; Ozcanhan, G; Zijlstra, S; Lindenbergh, A; Sijen, T

2016-03-01

Especially when minute evidentiary traces are analysed, background cell material unrelated to the crime may contribute to detectable levels in the genetic analyses. To gain understanding on the composition of human cell material residing on surfaces contributing to background traces, we performed DNA and mRNA profiling on samplings of various items. Samples were selected by considering events contributing to cell material deposits in exemplary activities (e.g. dragging a person by the trouser ankles), and can be grouped as public objects, private samples, transfer-related samples and washing machine experiments. Results show that high DNA yields do not necessarily relate to an increased number of contributors or to the detection of other cell types than skin. Background cellular material may be found on any type of public or private item. When a major contributor can be deduced in DNA profiles from private items, this can be a different person than the owner of the item. Also when a specific activity is performed and the areas of physical contact are analysed, the "perpetrator" does not necessarily represent the major contributor in the STR profile. Washing machine experiments show that transfer and persistence during laundry is limited for DNA and cell type dependent for RNA. Skin conditions such as the presence of sebum or sweat can promote DNA transfer. Results of this study, which encompasses 549 samples, increase our understanding regarding the prevalence of human cell material in background and activity scenarios. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The effect of winding and core support material on the thermal gain dependence of a fluxgate magnetometer sensor

NASA Astrophysics Data System (ADS)

Miles, David M.; Mann, Ian R.; Kale, Andy; Milling, David K.; Narod, Barry B.; Bennest, John R.; Barona, David; Unsworth, Martyn J.

2017-10-01

Fluxgate magnetometers are an important tool in geophysics and space physics but are typically sensitive to variations in sensor temperature. Changes in instrumental gain with temperature, thermal gain dependence, are thought to be predominantly due to changes in the geometry of the wire coils that sense the magnetic field and/or provide magnetic feedback. Scientific fluxgate magnetometers typically employ some form of temperature compensation and support and constrain wire sense coils with bobbins constructed from materials such as MACOR machinable ceramic (Corning Inc.) which are selected for their ultra-low thermal deformation rather than for robustness, cost, or ease of manufacturing. We present laboratory results comparing the performance of six geometrically and electrically matched fluxgate sensors in which the material used to support the windings and for the base of the sensor is varied. We use a novel, low-cost thermal calibration procedure based on a controlled sinusoidal magnetic source and quantitative spectral analysis to measure the thermal gain dependence of fluxgate magnetometer sensors at the ppm°C-1 level in a typical magnetically noisy university laboratory environment. We compare the thermal gain dependence of sensors built from MACOR, polyetheretherketone (PEEK) engineering plastic (virgin, 30 % glass filled and 30 % carbon filled), and acetal to examine the trade between the thermal properties of the material, the impact on the thermal gain dependence of the fluxgate, and the cost and ease of manufacture. We find that thermal gain dependence of the sensor varies as one half of the material properties of the bobbin supporting the wire sense coils rather than being directly related as has been historically thought. An experimental sensor constructed from 30 % glass-filled PEEK (21.6 ppm°C-1) had a thermal gain dependence within 5 ppm°C-1 of a traditional sensor constructed from MACOR ceramic (8.1 ppm°C-1). If a modest increase in thermal dependence can be tolerated or compensated, then 30 % glass-filled PEEK is a good candidate for future fluxgate sensors as it is more economical, easier to machine, lighter, and more robust than MACOR.

Noise, gain, and capture probability of p-type InAs-GaAs quantum-dot and quantum dot-in-well infrared photodetectors

NASA Astrophysics Data System (ADS)

Wolde, Seyoum; Lao, Yan-Feng; Unil Perera, A. G.; Zhang, Y. H.; Wang, T. M.; Kim, J. O.; Schuler-Sandy, Ted; Tian, Zhao-Bing; Krishna, S.

2017-06-01

We report experimental results showing how the noise in a Quantum-Dot Infrared photodetector (QDIP) and Quantum Dot-in-a-well (DWELL) varies with the electric field and temperature. At lower temperatures (below ˜100 K), the noise current of both types of detectors is dominated by generation-recombination (G-R) noise which is consistent with a mechanism of fluctuations driven by the electric field and thermal noise. The noise gain, capture probability, and carrier life time for bound-to-continuum or quasi-bound transitions in DWELL and QDIP structures are discussed. The capture probability of DWELL is found to be more than two times higher than the corresponding QDIP. Based on the analysis, structural parameters such as the numbers of active layers, the surface density of QDs, and the carrier capture or relaxation rate, type of material, and electric field are some of the optimization parameters identified to improve the gain of devices.

Preparing university students to lead K-12 engineering outreach programmes: a design experiment

NASA Astrophysics Data System (ADS)

Anthony, Anika B.; Greene, Howard; Post, Paul E.; Parkhurst, Andrew; Zhan, Xi

2016-11-01

This paper describes an engineering outreach programme designed to increase the interest of under-represented youth in engineering and to disseminate pre-engineering design challenge materials to K-12 educators and volunteers. Given university students' critical role as facilitators of the outreach programme, researchers conducted a two-year design experiment to examine the programme's effectiveness at preparing university students to lead pre-engineering activities. Pre- and post-surveys incorporated items from the Student Engagement sub-scale of the Teacher Sense of Efficacy Scale. Surveys were analysed using paired-samples t-test. Interview and open-ended survey data were analysed using discourse analysis and the constant comparative method. As a result of participation in the programme, university students reported a gain in efficacy to lead pre-engineering activities. The paper discusses programme features that supported efficacy gains and concludes with a set of design principles for developing learning environments that effectively prepare university students to facilitate pre-engineering outreach programmes.

Waking Up from Four Decades' Long Dream of Valorizing Agro-Food Byproducts: Toward Practical Applications of the Gained Knowledge.

PubMed

Domínguez-Perles, Raúl; Moreno, Diego A; García-Viguera, Cristina

2018-03-28

The late 1970s was the onset of literature about the first research outputs on alternatives to create added-value to agro-food byproducts focused on the reduction of the dependency on raw materials and, simultaneously, helping to reduce the environmental impacts of the agricultural activities. This trend, increased over the years and during the past decade, has been boosted by the growing concern of the socio-economic impact of wastes from agro-food activities, however, with little success of the proposed applications. Throughout four decades an array of studies have emerged, aimed to gain evidence on the relevance of innovation in the agro-food industry, as well as to overcome this situation. To our knowledge, only a few cases, summarized in the present perspective, represent the main alternatives currently available for the valorization of agro-food byproducts, with indications of some constraints that need to be addressed, in the coming years, to obtain a real profit from these products.

Development of active, nanoparticle, antimicrobial technologies for muscle-based packaging applications.

PubMed

Morris, Michael A; Padmanabhan, Sibu C; Cruz-Romero, Malco C; Cummins, Enda; Kerry, Joseph P

2017-10-01

Fresh and processed muscle-based foods are highly perishable food products and packaging plays a crucial role in providing containment so that the full effect of preservation can be achieved through the provision of shelf-life extension. Conventional packaging materials and systems have served the industry well, however, greater demands are being placed upon industrial packaging formats owing to the movement of muscle-based products to increasingly distant markets, as well as increased customer demands for longer product shelf-life and storage capability. Consequently, conventional packaging materials and systems will have to evolve to meet these challenges. This review presents some of the new strategies that have been developed by employing novel nanotechnological concepts which have demonstrated some promise in significantly extending the shelf-life of muscle-based foods by providing commercially-applicable, antimicrobially-active, smart packaging solutions. The primary focus of this paper is applied to subject aspects, such as; material chemistries employed, forming methods utilised, interactions of the packaging functionalities including nanomaterials employed with polymer substrates and how such materials ultimately affect microbes. In order that such materials become industrially feasible, it is important that safe, stable and commercially-viable packaging materials are shown to be producible and effective in order to gain public acceptance, legislative approval and industrial adoption. Copyright © 2017. Published by Elsevier Ltd.

Compact low-noise preamplifier for noise spectroscopy with biased photodiodes in cargo inspection systems

NASA Astrophysics Data System (ADS)

Benetti, Bob; Langeveld, Willem G. J.

2013-09-01

Noise Spectroscopy, a.k.a. Z-determination by Statistical Count-rate ANalysis (Z-SCAN), is a statistical technique to determine a quantity called the "noise figure" from digitized waveforms of pulses of transmitted x-rays in cargo inspection systems. Depending only on quantities related to the x-ray energies, it measures a characteristic of the transmitted x-ray spectrum, which depends on the atomic number, Z, of the material penetrated. The noise figure can thus be used for material separation. In an 80-detector prototype, scintillators are used with large-area photodiodes biased at 80V and digitized using 50-MSPS 12-bit ADC boards. We present an ultra-compact low-noise preamplifier design, with one high-gain and one low-gain channel per detector for improved dynamic range. To achieve adequate detection sensitivity and spatial resolution each dual-gain preamplifier channel must fit within a 12.7 mm wide circuit board footprint and maintain adequate noise immunity to conducted and radiated interference from adjacent channels. The novel design included iterative SPICE analysis of transient response, dynamic range, frequency response, and noise analysis to optimize the selection and configuration of amplifiers and filter response. We discuss low-noise active and passive components and low-noise techniques for circuit board layout that are essential to achieving the design goals, and how the completed circuit board performed in comparison to the predicted responses.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kristo, Michael J.; Gaffney, Amy M.; Marks, Naomi

Nuclear forensic science seeks to identify the origin of nuclear materials found outside regulatory control. It is increasingly recognized as an integral part of a robust nuclear security program. Our review highlights areas of active, evolving research in nuclear forensics, with a focus on analytical techniques commonly employed in Earth and planetary sciences. Applications of nuclear forensics to uranium ore concentrates (UOCs) are discussed first. UOCs have become an attractive target for nuclear forensic researchers because of the richness in impurities compared to materials produced later in the fuel cycle. Furthermore, the development of chronometric methods for age dating nuclearmore » materials is then discussed, with an emphasis on improvements in accuracy that have been gained from measurements of multiple radioisotopic systems. Finally, papers that report on casework are reviewed, to provide a window into current scientific practice.« less

Preparing and Testing a Magnetic Antimicrobial Silver Nanocomposite for Water Disinfection To Gain Experience at the Nanochemistry–Microbiology Interface

DOE PAGES

Furlan, Ping Y.; Fisher, Adam J.; Melcer, Michael E.; ...

2017-03-29

In this article, we describe a 2 h introductory laboratory procedure that prepares a novel magnetic antimicrobial activated carbon nanocomposite in which nanoscale sized magnetite and silver particles are incorporated (MACAg). The MACAg nanocomposite has achieved the synergistic properties derived from its components and demonstrated its applicability as an effective and recoverable antimicrobial agent for water disinfection. The principle is successfully illustrated by a significant reduction in the number of microbes in an Escherichia coli (E. coli) solution of 2 × 10 6 colony forming units following its treatment with MACAg for 10 min. The exercise allows the college studentsmore » to (1) be introduced to an exciting class of advanced materials, known as nanocomposites, at an early stage, (2) gain working experiences at nanochemistry–microbiology interface, and (3) see the use and experience the fun of chemistry. The experiment uses readily available materials, can be run in a general or introductory chemistry laboratory environment, and is well received and enjoyed by the students. Lastly, the experiment is also suitable for advanced high school students.« less

Preparing and Testing a Magnetic Antimicrobial Silver Nanocomposite for Water Disinfection To Gain Experience at the Nanochemistry–Microbiology Interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furlan, Ping Y.; Fisher, Adam J.; Melcer, Michael E.

In this article, we describe a 2 h introductory laboratory procedure that prepares a novel magnetic antimicrobial activated carbon nanocomposite in which nanoscale sized magnetite and silver particles are incorporated (MACAg). The MACAg nanocomposite has achieved the synergistic properties derived from its components and demonstrated its applicability as an effective and recoverable antimicrobial agent for water disinfection. The principle is successfully illustrated by a significant reduction in the number of microbes in an Escherichia coli (E. coli) solution of 2 × 10 6 colony forming units following its treatment with MACAg for 10 min. The exercise allows the college studentsmore » to (1) be introduced to an exciting class of advanced materials, known as nanocomposites, at an early stage, (2) gain working experiences at nanochemistry–microbiology interface, and (3) see the use and experience the fun of chemistry. The experiment uses readily available materials, can be run in a general or introductory chemistry laboratory environment, and is well received and enjoyed by the students. Lastly, the experiment is also suitable for advanced high school students.« less

Efficacy of problem based learning in a high school science classroom

NASA Astrophysics Data System (ADS)

Rissi, James Ryan

At the high school level, the maturity of the students, as well as constraints of the traditional high school (both in terms of class time, and number of students), impedes the use of the Problem-based instruction. But with more coaching, guidance, and planning, Problem-based Learning may be an effective teaching technique with secondary students. In recent years, the State of Michigan High School Content Expectations have emphasized the importance of inquiry and problem solving in the high school science classroom. In order to help students gain inquiry and problem solving skills, a move towards a problem-based curriculum and away from the didactic approach may lead to favorable results. In this study, the problem-based-learning framework was implemented in a high school Anatomy and Physiology classroom. Using pre-tests and post-tests over the material presented using the Problem-based technique, student comprehension and long-term retention of the material was monitored. It was found that Problem-based Learning produced comparable test performance when compared to traditional lecture, note-taking, and enrichment activities. In addition, students showed evidence of gaining research and team-working skills.

Rational Design of Molecular Ferroelectric Materials and Nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ducharme, Stephen

2012-09-25

The purpose of this project was to gain insight into the properties of molecular ferroelectrics through the detailed study of oligomer analogs of polyvinylidene fluoride (PVDF). By focusing on interactions at both the molecular level and the nanoscale level, we expect to gain improved understanding about the fundamental mechanism of ferroelectricity and its key properties. The research consisted of three complementary components: 1) Rational synthesis of VDF oligomers by Prof. Takacs' group; 2) Detailed structural and electrical studies of thin by Prof. Ducharme's Group; and 3) First-principles computational studies by DOE Lab Partner Dr. Serge Nakhman-son at Argonne National Laboratory.more » The main results of the work was a detailed understanding of the relationships between the molecular interactions and macroscopic phenomenology of fer-roelectricity VDF oligomers. This is valuable information supporting the development of im-proved electromechanical materials for, e.g., sonar, ultrasonic imaging, artificial muscles, and compliant actuators. Other potential applications include nonvolatile ferroelectric memories, heat-sensing imaging arrays, photovoltaic devices, and functional biomimetic materials. The pro-ject contributed to the training and professional development of undergraduate students and graduate students, post-doctoral assistants, and a high-school teacher. Project personnel took part in several outreach and education activities each year.« less

Temperature dependent absorption measurement of various transition metal doped laser materials

NASA Astrophysics Data System (ADS)

Horackova, Lucie; Šulc, Jan; Jelinkova, Helena; Jambunathan, Venkatesan; Lucianetti, Antonio; Mocek, Tomás.

2015-05-01

In recent years, there has been a vast development of high energy class lasers of the order of 100 J to kJ level which have potential applications in the field of science and technology. Many such systems use the gain media cooled at cryogenic temperatures which will help in enhancing the spectroscopic and thermo-optical properties. Nevertheless, parasitic effects like amplified spontaneous emission enhance and affect the overall efficiency. The best way to suppress this effect is to use cladding element attached to the gain material. Based on these facts, this work was focused on the systematic investigation of temperature dependent absorption of several materials doped with transition metals, which can be used as cladding, as laser gain material, or as passive Q-switching element. The Ti:sapphire, Cr:YAG, V:YAG, and Co:MALO samples were measured in temperature range from 80 K to 330 K by step of 50 K. Using Beer-Lambert law we estimated the absorption coefficient of these materials.

Weight gain in healthy pregnant women in relation to pre-pregnancy BMI, diet and physical activity.

PubMed

Merkx, Astrid; Ausems, Marlein; Budé, Luc; de Vries, Raymond; Nieuwenhuijze, Marianne J

2015-07-01

to explore gestational weight gain in healthy women in relation to pre-pregnancy Body Mass Index, diet and physical activity. a cross-sectional survey was conducted among 455 healthy pregnant women of all gestational ages receiving antenatal care from an independent midwife in the Netherlands. Weight gain was assessed using the Institute of Medicine (IOM) guidelines and classified as below, within, or above the guidelines. A multinomial regression analysis was performed with weight gain classifications as the dependent variable (within IOM-guidelines as reference). Independent variables were pre-pregnancy Body Mass Index, diet (broken down into consumption of vegetables, fruit and fish) and physical activity (motivation to engage in physical activity, pre-pregnancy physical activity and decline in physical activity during pregnancy). Covariates were age, gestational age, parity, ethnicity, family income, education, perceived sleep deprivation, satisfaction with pre-pregnancy weight, estimated prepregnancy body mass index, smoking, having a weight gain goal and having received weight gain advice from the midwife. forty-two per cent of the women surveyed gained weight within the guidelines. Fourteen per cent of the women gained weight below the guidelines and 44 per cent gained weight above the guidelines. Weight gain within the guidelines, compared to both above and below the guidelines, was not associated with pre-pregnancy Body Mass Index nor with diet. A decline in physical activity was associated with weight gain above the guidelines (OR 0.54, 95 per cent CI 0.33-0.89). Weight gain below the guidelines was seen more often in women who perceived a greater sleep deprivation (OR 1.20, 95 per cent CI 1.02-1.41). Weight gain above the guidelines was seen less often in Caucasian women in comparison to non-Caucasian women (OR 0.22, 95 per cent CI 0.08-0.56) and with women who did not stop smoking during pregnancy (OR 0.49, 95 per cent CI 0.25-0.95). a decline in physical activity was the only modifiable factor in our population associated with weight gain above the gain recommended by the guidelines. Prevention of reduced physical activity during pregnancy seems a promising approach to promoting healthy weight gain. Interventions to promote healthy weight gain should focus on all women, regardless of pre-pregnancy body mass index. Copyright © 2015 Elsevier Ltd. All rights reserved.

Oxidation Resistance of Materials Based on Ti3AlC2 Nanolaminate at 600 °C in Air.

PubMed

Ivasyshyn, Andrij; Ostash, Orest; Prikhna, Tatiana; Podhurska, Viktoriya; Basyuk, Tatiana

2016-12-01

The oxidation behavior of Ti3AlC2-based materials had been investigated at 600 °C in static air for 1000 h. It was shown that the intense increase of weight gain per unit surface area for sintered material with porosity of 22 % attributed to oxidation of the outer surface of the specimen and surfaces of pores in the bulk material. The oxidation kinetics of the hot-pressed Ti3AlC2-based material with 1 % porosity remarkably increased for the first 15 h and then slowly decreased. The weight gain per unit surface area for this material was 1.0 mg/cm(2) after exposition for 1000 h. The intense initial oxidation of Ti3AlC2-based materials can be eliminated by pre-oxidation treatment at 1200 °C in air for 2 h. As a result, the weight gain per unit surface area for the pre-oxidized material did not exceed 0.11 mg/cm(2) after 1000 h of exposition at 600 °C in air. It was demonstrated that the oxidation resistance of Ti3AlC2-based materials can be significantly improved by niobium addition.

Efficient storage mechanisms for building better supercapacitors

NASA Astrophysics Data System (ADS)

Salanne, M.; Rotenberg, B.; Naoi, K.; Kaneko, K.; Taberna, P.-L.; Grey, C. P.; Dunn, B.; Simon, P.

2016-06-01

Supercapacitors are electrochemical energy storage devices that operate on the simple mechanism of adsorption of ions from an electrolyte on a high-surface-area electrode. Over the past decade, the performance of supercapacitors has greatly improved, as electrode materials have been tuned at the nanoscale and electrolytes have gained an active role, enabling more efficient storage mechanisms. In porous carbon materials with subnanometre pores, the desolvation of the ions leads to surprisingly high capacitances. Oxide materials store charge by surface redox reactions, leading to the pseudocapacitive effect. Understanding the physical mechanisms underlying charge storage in these materials is important for further development of supercapacitors. Here we review recent progress, from both in situ experiments and advanced simulation techniques, in understanding the charge storage mechanism in carbon- and oxide-based supercapacitors. We also discuss the challenges that still need to be addressed for building better supercapacitors.

Transfer having a coupling coefficient higher than its active material

NASA Technical Reports Server (NTRS)

Lesieutre, George A. (Inventor); Davis, Christopher L. (Inventor)

2001-01-01

A coupling coefficient is a measure of the effectiveness with which a shape-changing material (or a device employing such a material) converts the energy in an imposed signal to useful mechanical energy. Device coupling coefficients are properties of the device and, although related to the material coupling coefficients, are generally different from them. This invention describes a class of devices wherein the apparent coupling coefficient can, in principle, approach 1.0, corresponding to perfect electromechanical energy conversion. The key feature of this class of devices is the use of destabilizing mechanical pre-loads to counter inherent stiffness. The approach is illustrated for piezoelectric and thermoelectrically actuated devices. The invention provides a way to simultaneously increase both displacement and force, distinguishing it from alternatives such as motion amplification, and allows transducer designers to achieve substantial performance gains for actuator and sensor devices.

Nuclear Forensic Science: Analysis of Nuclear Material Out of Regulatory Control

DOE PAGES

Kristo, Michael J.; Gaffney, Amy M.; Marks, Naomi; ...

2016-05-11

Nuclear forensic science seeks to identify the origin of nuclear materials found outside regulatory control. It is increasingly recognized as an integral part of a robust nuclear security program. Our review highlights areas of active, evolving research in nuclear forensics, with a focus on analytical techniques commonly employed in Earth and planetary sciences. Applications of nuclear forensics to uranium ore concentrates (UOCs) are discussed first. UOCs have become an attractive target for nuclear forensic researchers because of the richness in impurities compared to materials produced later in the fuel cycle. Furthermore, the development of chronometric methods for age dating nuclearmore » materials is then discussed, with an emphasis on improvements in accuracy that have been gained from measurements of multiple radioisotopic systems. Finally, papers that report on casework are reviewed, to provide a window into current scientific practice.« less

Electronic publishing in radiology: economics and the future.

PubMed

Chew, Felix S; Llewellyn, Kevin T; Olsen, Kathryn M

2004-11-01

Scholarly publishing is a large market involving thousands of peer-reviewed journals but a decreasing number of publishers. An economic model can be described in which authors give their work to publishers who then sell access to this work. Because each published article is a unique work with few if any substitutes, publishers have some degree of monopoly power and can price their products accordingly. The advent of desktop publishing using personal computers made it possible for individuals to publish material without publishers, an activity that gained momentum when the publishing medium shifted from paper to electronic, and from electronic publishing to the Internet. This activity destabilized the industry, and in the rush to gain market share by providing free content, unsustainable business models were created. Scholarly publishing is now dominated by a small number of multinational corporations that acquired many smaller publishing operations. As these companies have exercised their monopoly power, an open access movement has gained traction in which authors (or their institutions) initially pay for publication, but readers have free and open access to the published articles. This movement is in diametric opposition to the commercial publishing model, and it remains to be seen whether and how well the two can coexist in the future.

Short-Wave Infrared HgCdTe Electron Avalanche Photodiodes for Gated Viewing

NASA Astrophysics Data System (ADS)

Sieck, A.; Benecke, M.; Eich, D.; Oelmaier, R.; Wendler, J.; Figgemeier, H.

2018-06-01

Short-wave infrared (SWIR) HgCdTe electron avalanche photodiodes (eAPDs) with different doping profiles have been characterized for use in SWIR gated viewing systems. Gated viewing offers enhanced image contrast in scenes with clutter from the foreground or background. HgCdTe-based eAPDs show exponential gain-voltage characteristics and low excess noise and are, therefore, well suited for active imaging applications. The gain achievable at a fixed reverse voltage varies with the bandgap of the Hg1-xCdxTe detector material. We analyze current-voltage and gain-voltage plots measured on SWIR Hg1-xCdxTe eAPDs with x = 0.45, corresponding to a cutoff wavelength of 2.55 μm at 150 K. The cutoff has been chosen as a trade-off between achievable APD gain and operating temperature for SWIR gated-viewing systems with target distances of about 1000 m. Focal plane arrays with a readout-integrated circuit featuring a fast internal clock have been built and their performance with respect to gated viewing applications has been evaluated on a laboratory demonstrator for short distances. Future plans for a field demonstrator for distances up to 1000 m are described briefly at the end.

Nonpolar InGaN/GaN Core-Shell Single Nanowire Lasers.

PubMed

Li, Changyi; Wright, Jeremy B; Liu, Sheng; Lu, Ping; Figiel, Jeffrey J; Leung, Benjamin; Chow, Weng W; Brener, Igal; Koleske, Daniel D; Luk, Ting-Shan; Feezell, Daniel F; Brueck, S R J; Wang, George T

2017-02-08

We report lasing from nonpolar p-i-n InGaN/GaN multi-quantum well core-shell single-nanowire lasers by optical pumping at room temperature. The nanowire lasers were fabricated using a hybrid approach consisting of a top-down two-step etch process followed by a bottom-up regrowth process, enabling precise geometrical control and high material gain and optical confinement. The modal gain spectra and the gain curves of the core-shell nanowire lasers were measured using micro-photoluminescence and analyzed using the Hakki-Paoli method. Significantly lower lasing thresholds due to high optical gain were measured compared to previously reported semipolar InGaN/GaN core-shell nanowires, despite significantly shorter cavity lengths and reduced active region volume. Mode simulations show that due to the core-shell architecture, annular-shaped modes have higher optical confinement than solid transverse modes. The results show the viability of this p-i-n nonpolar core-shell nanowire architecture, previously investigated for next-generation light-emitting diodes, as low-threshold, coherent UV-visible nanoscale light emitters, and open a route toward monolithic, integrable, electrically injected single-nanowire lasers operating at room temperature.

Nonpolar InGaN/GaN core–shell single nanowire lasers

DOE PAGES

Li, Changyi; Wright, Jeremy Benjamin; Liu, Sheng; ...

2017-01-24

We report lasing from nonpolar p-i-n InGaN/GaN multi-quantum well core–shell single-nanowire lasers by optical pumping at room temperature. The nanowire lasers were fabricated using a hybrid approach consisting of a top-down two-step etch process followed by a bottom-up regrowth process, enabling precise geometrical control and high material gain and optical confinement. The modal gain spectra and the gain curves of the core–shell nanowire lasers were measured using micro-photoluminescence and analyzed using the Hakki-Paoli method. Significantly lower lasing thresholds due to high optical gain were measured compared to previously reported semipolar InGaN/GaN core–shell nanowires, despite significantly shorter cavity lengths and reducedmore » active region volume. Mode simulations show that due to the core–shell architecture, annular-shaped modes have higher optical confinement than solid transverse modes. Furthermore, the results show the viability of this p-i-n nonpolar core–shell nanowire architecture, previously investigated for next-generation light-emitting diodes, as low-threshold, coherent UV–visible nanoscale light emitters, and open a route toward monolithic, integrable, electrically injected single-nanowire lasers operating at room temperature.« less

Supplemental Instruction in Introductory Biology I: Enhancing the Performance and Retention of Underrepresented Minority Students

PubMed Central

Peterfreund, Alan R.; Xenos, Samuel P.; Bayliss, Frank; Carnal, Nancy

2007-01-01

Supplemental instruction classes have been shown in many studies to enhance performance in the supported courses and even to improve graduation rates. Generally, there has been little evidence of a differential impact on students from different ethnic/racial backgrounds. At San Francisco State University, however, supplemental instruction in the Introductory Biology I class is associated with even more dramatic gains among students from underrepresented minority populations than the gains found among their peers. These gains do not seem to be the product of better students availing themselves of supplemental instruction or other outside factors. The Introductory Biology I class consists of a team-taught lecture component, taught in a large lecture classroom, and a laboratory component where students participate in smaller lab sections. Students are expected to master an understanding of basic concepts, content, and vocabulary in biology as well as gain laboratory investigation skills and experience applying scientific methodology. In this context, supplemental instruction classes are cooperative learning environments where students participate in learning activities that complement the course material, focusing on student misconceptions and difficulties, construction of a scaffolded knowledge base, applications involving problem solving, and articulation of constructs with peers. PMID:17785403

Increased Preclass Preparation Underlies Student Outcome Improvement in the Flipped Classroom

PubMed Central

Gross, David; Pietri, Evava S.; Anderson, Gordon; Moyano-Camihort, Karin; Graham, Mark J.

2015-01-01

Active-learning environments such as those found in a flipped classroom are known to increase student performance, although how these gains are realized over the course of a semester is less well understood. In an upper-level lecture course designed primarily for biochemistry majors, we examine how students attain improved learning outcomes, as measured by exam scores, when the course is converted to a more active flipped format. The context is a physical chemistry course catering to life science majors in which approximately half of the lecture material is placed online and in-class problem-solving activities are increased, while total class time is reduced. We find that exam performance significantly improves by nearly 12% in the flipped-format course, due in part to students interacting with course material in a more timely and accurate manner. We also find that the positive effects of the flipped class are most pronounced for students with lower grade point averages and for female students. PMID:26396151

Optical amplifier operating at 1.3 microns useful for telecommunications and based on dysprosium-doped metal chloride host materials

DOEpatents

Page, R.H.; Schaffers, K.I.; Payne, S.A.; Krupke, W.F.; Beach, R.J.

1997-12-02

Dysprosium-doped metal chloride materials offer laser properties advantageous for use as optical amplifiers in the 1.3 {micro}m telecommunications fiber optic network. The upper laser level is characterized by a millisecond lifetime, the host material possesses a moderately low refractive index, and the gain peak occurs near 1.31 {micro}m. Related halide materials, including bromides and iodides, are also useful. The Dy{sup 3+}-doped metal chlorides can be pumped with laser diodes and yield 1.3 {micro}m signal gain levels significantly beyond those currently available. 9 figs.

Optical amplifier operating at 1.3 microns useful for telecommunications and based on dysprosium-doped metal chloride host materials

DOEpatents

Page, Ralph H.; Schaffers, Kathleen I.; Payne, Stephen A.; Krupke, William F.; Beach, Raymond J.

1997-01-01

Dysprosium-doped metal chloride materials offer laser properties advantageous for use as optical amplifiers in the 1.3 .mu.m telecommunications fiber optic network. The upper laser level is characterized by a millisecond lifetime, the host material possesses a moderately low refractive index, and the gain peak occurs near 1.31 .mu.m. Related halide materials, including bromides and iodides, are also useful. The Dy.sup.3+ -doped metal chlorides can be pumped with laser diodes and yield 1.3 .mu.m signal gain levels significantly beyond those currently available.

On the way to the creation of next generation photoactive materials.

PubMed

Emeline, A V; Kuznetsov, V N; Ryabchuk, V K; Serpone, N

2012-11-01

Transition from first- to second-generation photocatalysts has followed the notion that greater absorption of light in the visible region would yield greater spectral sensitivity and greater photoactivity. Though a promising strategy, in practice, it did not meet expectation because of various side issues, which in many cases has led to loss of photoactivity and chemical reactivity. This article examines some earlier notions that arose from applications of different metal oxides (e.g., TiO(2), ZnO, MgO among others) that made these oxides good photocatalysts in many processes. Phenomena that proved relevant in developing next generation photoactive materials are considered: the dependence of the activity of photocatalysts on the band gap energy, the spectral variations of the activity of photoactive materials, and the spectral variations of selectivity of photoactive materials. The tendency to decrease the energy of actinic photons through doping in forming second-generation photocatalysts is completely opposite the fundamental observation in first-generation photocatalysts whereby the activity increased with increasing band gap energy. Extension of spectral sensitivity of second-generation photoactive materials also caused a decrease of their photoactivity; hence, some notions are reconsidered to produce next(third) generation photoactive materials. The article proposes the following concepts to develop next generation photocatalysts: (1) multi(two)-photon excitation of photoactive materials with lower energy photons to achieve the same excited state as with higher energy photons, (2) utilization of heterojunctions to drive electronic processes in the desired direction, and (3) selective photoexcitation of localized electronic states to gain better selectivity.

Heat gain from thermal radiation through protective clothing with different insulation, reflectivity and vapour permeability.

PubMed

Bröde, Peter; Kuklane, Kalev; Candas, Victor; Den Hartog, Emiel A; Griefahn, Barbara; Holmér, Ingvar; Meinander, Harriet; Nocker, Wolfgang; Richards, Mark; Havenith, George

2010-01-01

The heat transferred through protective clothing under long wave radiation compared to a reference condition without radiant stress was determined in thermal manikin experiments. The influence of clothing insulation and reflectivity, and the interaction with wind and wet underclothing were considered. Garments with different outer materials and colours and additionally an aluminised reflective suit were combined with different number and types of dry and pre-wetted underwear layers. Under radiant stress, whole body heat loss decreased, i.e., heat gain occurred compared to the reference. This heat gain increased with radiation intensity, and decreased with air velocity and clothing insulation. Except for the reflective outer layer that showed only minimal heat gain over the whole range of radiation intensities, the influence of the outer garments' material and colour was small with dry clothing. Wetting the underclothing for simulating sweat accumulation, however, caused differing effects with higher heat gain in less permeable garments.

Stability studies of immobilized lipase on rice husk and eggshell membrane

NASA Astrophysics Data System (ADS)

Abdulla, R.; Sanny, S. A.; Derman, E.

2017-06-01

Lipase immobilization for biodiesel production is gaining importance day by day. In this study, lipase from Burkholderia cepacia was immobilized on activated support materials namely rice husk and egg shell membrane. Both rice husk and eggshell membrane are natural wastes that holds a lot of potential as immobilization matrix. Rice husk and eggshell membrane were activated with glutaraldehyde. Lipase was immobilized on the glutaraldehyde-activated support material through adsorption. Immobilization efficiency together with enzyme activity was observed to choose the highest enzyme loading for further stability studies. Immobilization efficiency of lipase on rice husk was 81 as compared to an immobilization efficiency of 87 on eggshell membrane. Immobilized lipase on eggshell membrane exhibited higher enzyme activity as compared to immobilized lipase on rice husk. Eggshell membrane also reported higher stability than rice husk as immobilization matrix. Both types of immobilized lipase retatined its activity after ten cycles of reuse. In short, eggshell membrane showed to be a better immobilization platform for lipase as compared to rice husk. However, with further improvement in technique of immobilization, the stability of both types of immobilized lipase can be improved to a greater extent.

Performance analysis of GeSn-alloy-based multiple quantum well transistor laser

NASA Astrophysics Data System (ADS)

Ranjan, Ravi; Pareek, Prakash; Anwer Askari, Syed Sadique; Das, Mukul K.

2018-02-01

The Group IV Photonics (GFP) which include an alloy of Si, Ge & Sn that gives a direct bandgap material (GeSn, SiGeSn) in near and mid-IR region used as an active material in photonics devices. The multiple quantum well SiGeSn/GeSn transistor laser structure is considered in this paper and performance parameters are evaluated for the same. The result shows that the threshold base current density (2.6 kA/cm2) for the proposed device initially decreases with increasing number of quantum well (QW) and later on it saturates. The current gain and output photon density of the device decreases and increases respectively, with increasing number of QW.

On missing Data Treatment for degraded video and film archives: a survey and a new Bayesian approach.

PubMed

Kokaram, Anil C

2004-03-01

Image sequence restoration has been steadily gaining in importance with the increasing prevalence of visual digital media. The demand for content increases the pressure on archives to automate their restoration activities for preservation of the cultural heritage that they hold. There are many defects that affect archived visual material and one central issue is that of Dirt and Sparkle, or "Blotches." Research in archive restoration has been conducted for more than a decade and this paper places that material in context to highlight the advances made during that time. The paper also presents a new and simpler Bayesian framework that achieves joint processing of noise, missing data, and occlusion.

Components for IFOG based inertial measurement units using active and passive polymer materials

NASA Astrophysics Data System (ADS)

Ashley, Paul R.; Temmen, Mark G.; Diffey, William M.; Sanghadasa, Mohan; Bramson, Michael D.; Lindsay, Geoffrey A.; Guenthner, Andrew J.

2006-08-01

Highly accurate, compact, and low cost inertial measurement units (IMUs) are needed for precision guidance in navigation systems. Active and passive polymer materials have been successfully used in fabricating two of the key guided-wave components, the phase modulator and the optical transceiver, for IMUs based on the interferometric fiber optic gyroscope (IFOG) technology. Advanced hybrid waveguide fabrication processes and novel optical integration techniques have been introduced. Backscatter compensated low loss phase modulators with low half-wave drive voltage (V π) have been fabricated with CLD- and FTC- type high performance electro-optic chromophores. A silicon-bench architecture has been used in fabricating high gain low noise transceivers with high optical power while maintaining the spectral quality and long lifetime. Gyro bias stability of less than 0.02 deg/hr has been demonstrated with these components. A review of the novel concepts introduced, fabrication and integration techniques developed and performance achieved are presented.

Dementia, distributed interactional competence and social membership.

PubMed

Gjernes, Trude; Måseide, Per

2015-12-01

The article analyzes how a person with dementia playing a guitar collaborates with other people in a joint activity. The analysis shows that a person with dementia may gain social membership in a group of persons with and without dementia through social interaction, collaboration, scaffolding and use of material anchors. It shows that interactional skills as well as skills as guitar player are not only products of a mind-body system, but also a product of collaboration between different actors with different participant statuses in a particular situation. The guitar player's mind emerges in the social context of the joint activity and scaffolding. Scaffolding comes from interactive moves from the other participants without dementia and from the guitar. The guitar represents a material anchor. It is a tool for participation, experiences of pleasure, and coping, but it is also a challenge that requires management of face threatening events. Copyright © 2015 Elsevier Inc. All rights reserved.

Recent progress in high gain InAs avalanche photodiodes (Presentation Recording)

NASA Astrophysics Data System (ADS)

Bank, Seth; Maddox, Scott J.; Sun, Wenlu; Nair, Hari P.; Campbell, Joe C.

2015-08-01

InAs possesses nearly ideal material properties for the fabrication of near- and mid-infrared avalanche photodiodes (APDs), which result in strong electron-initiated impact ionization and negligible hole-initiated impact ionization [1]. Consequently, InAs multiplication regions exhibit several appealing characteristics, including extremely low excess noise factors and bandwidth independent of gain [2], [3]. These properties make InAs APDs attractive for a number of near- and mid-infrared sensing applications including remote gas sensing, light detection and ranging (LIDAR), and both active and passive imaging. Here, we discuss our recent advances in the growth and fabrication of high gain, low noise InAs APDs. Devices yielded room temperature multiplication gains >300, with much reduced (~10x) lower dark current densities. We will also discuss a likely key contributor to our current performance limitations: silicon diffusion into the intrinsic (multiplication) region from the underlying n-type layer during growth. Future work will focus on increasing the intrinsic region thickness, targeting gains >1000. This work was supported by the Army Research Office (W911NF-10-1-0391). [1] A. R. J. Marshall, C. H. Tan, M. J. Steer, and J. P. R. David, "Electron dominated impact ionization and avalanche gain characteristics in InAs photodiodes," Applied Physics Letters, vol. 93, p. 111107, 2008. [2] A. R. J. Marshall, A. Krysa, S. Zhang, A. S. Idris, S. Xie, J. P. R. David, and C. H. Tan, "High gain InAs avalanche photodiodes," in 6th EMRS DTC Technical Conference, Edinburgh, Scotland, UK, 2009. [3] S. J. Maddox, W. Sun, Z. Lu, H. P. Nair, J. C. Campbell, and S. R. Bank, "Enhanced low-noise gain from InAs avalanche photodiodes with reduced dark current and background doping," Applied Physics Letters, vol. 101, no. 15, pp. 151124-151124-3, Oct. 2012.

Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal

PubMed Central

Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I.; Wang, Jiyang

2016-01-01

With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc. PMID:27461819

A universal preconditioner for simulating condensed phase materials.

PubMed

Packwood, David; Kermode, James; Mones, Letif; Bernstein, Noam; Woolley, John; Gould, Nicholas; Ortner, Christoph; Csányi, Gábor

2016-04-28

We introduce a universal sparse preconditioner that accelerates geometry optimisation and saddle point search tasks that are common in the atomic scale simulation of materials. Our preconditioner is based on the neighbourhood structure and we demonstrate the gain in computational efficiency in a wide range of materials that include metals, insulators, and molecular solids. The simple structure of the preconditioner means that the gains can be realised in practice not only when using expensive electronic structure models but also for fast empirical potentials. Even for relatively small systems of a few hundred atoms, we observe speedups of a factor of two or more, and the gain grows with system size. An open source Python implementation within the Atomic Simulation Environment is available, offering interfaces to a wide range of atomistic codes.

A universal preconditioner for simulating condensed phase materials

NASA Astrophysics Data System (ADS)

Packwood, David; Kermode, James; Mones, Letif; Bernstein, Noam; Woolley, John; Gould, Nicholas; Ortner, Christoph; Csányi, Gábor

2016-04-01

We introduce a universal sparse preconditioner that accelerates geometry optimisation and saddle point search tasks that are common in the atomic scale simulation of materials. Our preconditioner is based on the neighbourhood structure and we demonstrate the gain in computational efficiency in a wide range of materials that include metals, insulators, and molecular solids. The simple structure of the preconditioner means that the gains can be realised in practice not only when using expensive electronic structure models but also for fast empirical potentials. Even for relatively small systems of a few hundred atoms, we observe speedups of a factor of two or more, and the gain grows with system size. An open source Python implementation within the Atomic Simulation Environment is available, offering interfaces to a wide range of atomistic codes.

Electro-Optically Active Monomers: Synthesis and Characterization of Thin Films of Liquid Crystalline Substituted Polyacetylenes

NASA Technical Reports Server (NTRS)

Duran, R. S.

1995-01-01

The overall objective of this study was the description of the behavior of mesogen substituted acetylene monomers and polymers in monolayer films at the air/water interface and as multilayer films including the formation of such films. Fundamental knowledge to be gained would include the effect of balancing hydrophilic and hydrophobic tendencies in a molecule more complex than the classical fatty acids or lipids. The effect of molecular shape on the packing and thus the ultimate stability of monolayers formed from these new molecules was explored. The work takes on the challenge of preorienting monomers in well-ordered arrays prior to attempting polymerization with the hope that order would be preserved in any resulting polymer. New knowledge gained with regard to the acetylenic monomers includes processing of the acetylene monomer into multi-layer films, followed by the design and synthesis of a second generation of improved monomer structure for superior LBK film transfer properties. A third generation of acetylenic monomer was synthesized which approaches more closely the goal of solid state polymerization of these materials. A parallel study took a different approach. The materials are pre-formed poly(phenylene-acetylene) polymers so questions about reactivity are mute. The materials are a variation on the well-known hairy-rod polymers with regard to their Langmuir film-forming properties. Overall, the goal was to demonstrate that these polymers could be processed into NLO materials with novel polar order.

Active-learning strategies to develop health literacy knowledge and skills.

PubMed

Devraj, Radhika; Butler, Lakesha M; Gupchup, Gireesh V; Poirier, Therese I

2010-10-11

To implement active-learning exercises in a required pharmacy course and assess their impact on students' knowledge and confidence in identifying and communicating with patients with low health literacy, as part of a required course in cultural competency, health literacy, and health beliefs. Active-learning activities including administering health literacy assessments, identifying informal signs of low health literacy, conducting mock patient counseling sessions, rating the readability of drug information, analyzing information in drug advertisements, and writing patient education materials were incorporated into the 6-sesssion health literacy portion of the course. A pretest and posttest showed that students' knowledge of health literacy increased, and a retrospective pretest found improvement in students' confidence in their ability to care for patients with low health literacy. In-class discussions provided informal evidence that students gained new knowledge from the active-learning activities. The addition of active-learning activities was effective in teaching health literacy concepts to pharmacy students.

Low-CO2 Acid-Base Binders Made with Fly Ash

NASA Astrophysics Data System (ADS)

Erdogan, S. T.

2016-12-01

Portland cement (PC) is the ubiquitous binding material for constructions works in urban areas. It is, however, responsible for 5-10 % of all anthropogenic CO2 emissions, nearly half of which arise from the decomposition of calcareous raw materials, and the other half from kiln fuel combustion and cement clinker grinding operations. As such, PC production contributes to global warming and climate change. Lately, efforts to develop alternative binders with lower greenhouse gas emissions have gained interest. An important class of such binders is geopolymers, typically formed by activating natural or waste materials with suitable alkaline solutions. These binders can have very low CO2 emissions from grinding of the starting materials, and some from the production of the activating chemical but the total CO2 emissions can be as low as 1/5th - 1/10th of those of PC concrete mixtures with comparable properties. Less commonly researched, acidic activating chemicals can also be used with powder materials to produce pastes that can set and harden into durable solids. One such powder is fly ash from coal-burning power plants. This ash is mostly stockpiled and can be an environmental hazard such as exacerbating air pollution in cities. This study investigates the chemical activation of fly ashes from Turkey using solutions of acids such as orthophosphoric acid. Amorphous and crystalline reaction products are observed to form, yielding a strong binder that sets much more rapidly than PC-based mixtures or alkali-activated geopolymers. As the change in the rheological properties and mechanical properties of these pastes can be balanced by combining different ashes, as well as by adjusting solution properties, they can offer environmental, energetic, and economical advantages over conventional PC-based mixtures.

Compact, high power, energy efficient transmit systems for UUVs using single crystal transducers

NASA Astrophysics Data System (ADS)

Robinson, Harold

2004-05-01

UUVs are currently being designed to perform a multiplitude of tasks in ocean exploration and Naval warfighting. Many of these tasks require the use of active acoustic projectors, and many may require the UUV to operate independently for hours, days, or even weeks. In order for a UUV to be as versatile as possible, its active transmit system must be versatile as well, implying that broad acoustic bandwidths are a must. However, due to size and battery life limitations, this broadband system must also be compact and energy efficient. By virtue of their extraordinary material properties, ferroelectric single crystals are the ideal transduction material for developing such broadband systems. The effect of their high coupling factor on transmit systems shall be illustrated by showing the dramatic impact on amplifier size, power factor, and acoustic response that is possible using these materials. In particular, a transducer built with these materials can be well matched to the power amplifier, i.e., 80% or more of the amplifier power reaches the transducer, over decades of frequency. Measured results from several prototype single crystal transducers shall be presented to demonstrate that the theoretical gains are actually realizable in practical devices. [Work sponsored by DARPA.

Segregated and integrated coding of reward and punishment in the cingulate cortex.

PubMed

Fujiwara, Juri; Tobler, Philippe N; Taira, Masato; Iijima, Toshio; Tsutsui, Ken-Ichiro

2009-06-01

Reward and punishment have opposite affective value but are both processed by the cingulate cortex. However, it is unclear whether the positive and negative affective values of monetary reward and punishment are processed by separate or common subregions of the cingulate cortex. We performed a functional magnetic resonance imaging study using a free-choice task and compared cingulate activations for different levels of monetary gain and loss. Gain-specific activation (increasing activation for increasing gain, but no activation change in relation to loss) occurred mainly in the anterior part of the anterior cingulate and in the posterior cingulate cortex. Conversely, loss-specific activation (increasing activation for increasing loss, but no activation change in relation to gain) occurred between these areas, in the middle and posterior part of the anterior cingulate. Integrated coding of gain and loss (increasing activation throughout the full range, from biggest loss to biggest gain) occurred in the dorsal part of the anterior cingulate, at the border with the medial prefrontal cortex. Finally, unspecific activation increases to both gains and losses (increasing activation to increasing gains and increasing losses, possibly reflecting attention) occurred in dorsal and middle regions of the cingulate cortex. Together, these results suggest separate and common coding of monetary reward and punishment in distinct subregions of the cingulate cortex. Further meta-analysis suggested that the presently found reward- and punishment-specific areas overlapped with those processing positive and negative emotions, respectively.

20 CFR 220.29 - Work that is considered substantial gainful activity.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Employment § 220.29 Work that is considered substantial gainful activity. Work is considered to be substantial gainful activity if it— (a) Involves doing significant and productive physical or mental duties... activity. 220.29 Section 220.29 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE...

20 CFR 220.29 - Work that is considered substantial gainful activity.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Employment § 220.29 Work that is considered substantial gainful activity. Work is considered to be substantial gainful activity if it— (a) Involves doing significant and productive physical or mental duties... activity. 220.29 Section 220.29 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE...

20 CFR 229.85 - Substantial gainful activity by blind employee or child.

Code of Federal Regulations, 2011 CFR

2011-04-01

... substantial gainful activity that does not require skills or ability used in his or her previous work. However... in any type of substantial gainful activity which requires skills or abilities comparable to those of...

Extending brain-training to the affective domain: increasing cognitive and affective executive control through emotional working memory training.

PubMed

Schweizer, Susanne; Hampshire, Adam; Dalgleish, Tim

2011-01-01

So-called 'brain-training' programs are a huge commercial success. However, empirical evidence regarding their effectiveness and generalizability remains equivocal. This study investigated whether brain-training (working memory [WM] training) improves cognitive functions beyond the training task (transfer effects), especially regarding the control of emotional material since it constitutes much of the information we process daily. Forty-five participants received WM training using either emotional or neutral material, or an undemanding control task. WM training, regardless of training material, led to transfer gains on another WM task and in fluid intelligence. However, only brain-training with emotional material yielded transferable gains to improved control over affective information on an emotional Stroop task. The data support the reality of transferable benefits of demanding WM training and suggest that transferable gains across to affective contexts require training with material congruent to those contexts. These findings constitute preliminary evidence that intensive cognitively demanding brain-training can improve not only our abstract problem-solving capacity, but also ameliorate cognitive control processes (e.g. decision-making) in our daily emotive environments.

Parameter Measurement Methods for Interfacing Hydraulic Systems with Microelectronic Instruments and Controllers.

DTIC Science & Technology

1983-11-01

successfully. I- Accession For NTIS -GO iiiONa DTIC TAB t Unannounced - Justificatio Distribution/ I Availability Codes vail and/or DIst Special IA-11...terms of initial signal power. An active sensor must be excited externally. Such a sensor receives its power from an external source and merely modulates...electrons in the material to gain L enough energy to be emitted. The voltage source causes a positive potential to be felt on the collector, thus causing the

Nanocomposites: suitable alternatives as antimicrobial agents

NASA Astrophysics Data System (ADS)

Matharu, Rupy Kaur; Ciric, Lena; Edirisinghe, Mohan

2018-07-01

The exploration of nanocomposites has gained a strong research following over the last decade. These materials have been heavily exploited in several fields, with applications ranging from biosensors to biomedicine. Among these applications, great advances have been made in the field of microbiology, specifically as antimicrobial agents. This review aims to provide a comprehensive account of various nanocomposites that elucidate promising antimicrobial activity. The composition, physical and chemical properties, as well as the antimicrobial performance of these nanocomposites, are discussed in detail.

20 CFR 404.1573 - General information about work activity.

Code of Federal Regulations, 2011 CFR

2011-04-01

... business, this tends to show that you have the ability to work at the substantial gainful activity level... working at the substantial gainful activity level. If you are unable, because of your impairments, to do..., this does not show that you are working at the substantial gainful activity level. (c) If your work is...

20 CFR 404.1573 - General information about work activity.

Code of Federal Regulations, 2010 CFR

2010-04-01

... working at the substantial gainful activity level. If you are unable, because of your impairments, to do... people doing similar work, this may show that you are not working at the substantial gainful activity..., this does not show that you are working at the substantial gainful activity level. (c) If your work is...

Reducing Heat Gains and Cooling Loads Through Roof Structure Configurations of A House in Medan

NASA Astrophysics Data System (ADS)

Handayani Lubis, Irma; Donny Koerniawan, Mochamad

2018-05-01

Heat gains and heat losses through building surfaces are the main factors that determine the building’s cooling and heating loads. Roof as a building surface that has the most exposed area to the sun, contribute most of heat gains in the building. Therefore, the amount of solar heat gains on the roofs need to be minimized by roof structure configurations. This research aims to discover the optimization of roof structure configurations (coating material, structure material, inclination, overhang, and insulation) as one of passive design strategies that reduce heat gains and cooling loads of a house in Medan. The result showed that case four, white-painted metal roof combined with 45° roof pitched, 1.5m overhang, and addition of insulation, indicates the minimum heat gains production and the less cooling loads during clear sky day but not in the overcast sky condition. In conclusion, heat gains and cooling loads of a house in Medan could be diminished during clear sky day by the addition of roof coating with high reflectance low solar absorbtance, the slope roof, the extension of wider veranda, and the addition of insulation in the roof structure.

Two stage dual gate MESFET monolithic gain control amplifier for Ka-band

NASA Technical Reports Server (NTRS)

Sokolov, V.; Geddes, J.; Contolatis, A.

1987-01-01

A monolithic two stage gain control amplifier has been developed using submicron gate length dual gate MESFETs fabricated on ion implanted material. The amplifier has a gain of 12 dB at 30 GHz with a gain control range of over 30 dB. This ion implanted monolithic IC is readily integrable with other phased array receiver functions such as low noise amplifiers and phase shifters.

A universal preconditioner for simulating condensed phase materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Packwood, David; Ortner, Christoph, E-mail: c.ortner@warwick.ac.uk; Kermode, James, E-mail: j.r.kermode@warwick.ac.uk

2016-04-28

We introduce a universal sparse preconditioner that accelerates geometry optimisation and saddle point search tasks that are common in the atomic scale simulation of materials. Our preconditioner is based on the neighbourhood structure and we demonstrate the gain in computational efficiency in a wide range of materials that include metals, insulators, and molecular solids. The simple structure of the preconditioner means that the gains can be realised in practice not only when using expensive electronic structure models but also for fast empirical potentials. Even for relatively small systems of a few hundred atoms, we observe speedups of a factor ofmore » two or more, and the gain grows with system size. An open source Python implementation within the Atomic Simulation Environment is available, offering interfaces to a wide range of atomistic codes.« less

Insights to regenerate materials: learning from nature

NASA Astrophysics Data System (ADS)

García-Aznar, J. M.; Valero, C.; Gómez-Benito, M. J.; Javierre, E.

2016-08-01

Self-healing materials, both biological and engineered, integrate the ability to repair themselves and recover their functionality using the resources inherently available to them. Although significant advances have been made, in recent years, for the design of different concepts of self-healing materials, this work aims to provide some insights into how living materials are able to regenerate or heal when a fracture or injury occurs. The main sensors that regulate this adaptive and regenerative behavior are the cells. These are able to sense the mechanical alterations in their surroundings and regulate their activity in order to remove dead tissue and/or create new tissue. Therefore, understanding how cells are able to regenerate tissues under complex and multiphysics conditions can define the biomimetics guidelines to heal through inert or traditional engineering materials. In this work, we present a combination of experiments and different kinds of multiscale and multiphysics models in order to understand how mechanics regulate some mechanisms at cell and tissue level. This combination of results aims to gain insight into the development of novel strategies for self-healing materials, mimicking the behavior induced by cells and biological tissues.

Electron Radiation Effects on Candidate Solar Sail Material

NASA Technical Reports Server (NTRS)

Edwards, David L.; Hollerman, William A.; Hubbs, Whitney S.; Gray, Perry A.; Wertz, George E.; Hoppe, David T.; Nehls, Mary K.; Semmel, Charles L.

2003-01-01

Solar sailing is a unique form of propulsion where a spacecraft gains momentum from incident photons. Solar sails are not limited by reaction mass and provide continual acceleration, reduced only by the lifetime of the lightweight film in the space environment and the distance to the Sun. Once thought to be difficult or impossible, solar sailing has come out of science fiction and into the realm of possibility. Any spacecraft using this propulsion method would need to deploy a thin sail that could be as large as many kilometers in extent. The availability of strong, ultra lightweight, and radiation resistant materials will determine the future of solar sailing. The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) is concentrating research into the utilization of ultra lightweight materials for spacecraft propulsion. The Space Environmental Effects Team at MSFC is actively characterizing candidate solar sail material to evaluate the thermo-optical and mechanical properties after exposure to space environmental effects. This paper will describe the irradiation of candidate solar sail materials to energetic electrons, in vacuum, to determine the hardness of several candidate sail materials.

Organic Lasers: Recent Developments on Materials, Device Geometries, and Fabrication Techniques.

PubMed

Kuehne, Alexander J C; Gather, Malte C

2016-11-09

Organic dyes have been used as gain medium for lasers since the 1960s, long before the advent of today's organic electronic devices. Organic gain materials are highly attractive for lasing due to their chemical tunability and large stimulated emission cross section. While the traditional dye laser has been largely replaced by solid-state lasers, a number of new and miniaturized organic lasers have emerged that hold great potential for lab-on-chip applications, biointegration, low-cost sensing and related areas, which benefit from the unique properties of organic gain materials. On the fundamental level, these include high exciton binding energy, low refractive index (compared to inorganic semiconductors), and ease of spectral and chemical tuning. On a technological level, mechanical flexibility and compatibility with simple processing techniques such as printing, roll-to-roll, self-assembly, and soft-lithography are most relevant. Here, the authors provide a comprehensive review of the developments in the field over the past decade, discussing recent advances in organic gain materials, which are today often based on solid-state organic semiconductors, as well as optical feedback structures, and device fabrication. Recent efforts toward continuous wave operation and electrical pumping of solid-state organic lasers are reviewed, and new device concepts and emerging applications are summarized.

Photogating in Low Dimensional Photodetectors

PubMed Central

Fang, Hehai

2017-01-01

Abstract Low dimensional materials including quantum dots, nanowires, 2D materials, and so forth have attracted increasing research interests for electronic and optoelectronic devices in recent years. Photogating, which is usually observed in photodetectors based on low dimensional materials and their hybrid structures, is demonstrated to play an important role. Photogating is considered as a way of conductance modulation through photoinduced gate voltage instead of simply and totally attributing it to trap states. This review first focuses on the gain of photogating and reveals the distinction from conventional photoconductive effect. The trap‐ and hybrid‐induced photogating including their origins, formations, and characteristics are subsequently discussed. Then, the recent progress on trap‐ and hybrid‐induced photogating in low dimensional photodetectors is elaborated. Though a high gain bandwidth product as high as 109 Hz is reported in several cases, a trade‐off between gain and bandwidth has to be made for this type of photogating. The general photogating is put forward according to another three reported studies very recently. General photogating may enable simultaneous high gain and high bandwidth, paving the way to explore novel high‐performance photodetectors. PMID:29270342

Chromosomal Gains at 9q Characterize Enteropathy-Type T-Cell Lymphoma

PubMed Central

Zettl, Andreas; Ott, German; Makulik, Angela; Katzenberger, Tiemo; Starostik, Petr; Eichler, Thorsten; Puppe, Bernhard; Bentz, Martin; Müller-Hermelink, Hans Konrad; Chott, Andreas

2002-01-01

Genetic alterations in enteropathy-type T-cell lymphoma (ETL) are unknown so far. In this series, 38 cases of ETL were analyzed by comparative genomic hybridization (CGH). CGH revealed chromosomal imbalances in 87% of cases analyzed, with recurrent gains of genetic material involving chromosomes 9q (in 58% of cases), 7q (24%), 5q (18%), and 1q (16%). Recurrent losses of genetic material occurred on chromosomes 8p and 13q (24% each), and 9p (18%). In this first systematic genetic study on ETL, chromosomal gains on 9q (minimal overlapping region 9q33-q34) were found to be highly characteristic of ETL. Fluorescence in situ hybridization analysis on four cases of ETL, using a probe for 9q34, indicated frequent and multiple gains of chromosomal material at 9q34 (up to nine signals per case). Among 16 patients with ETL who survived initial disease presentation, patients with more than three chromosomal gains or losses (n = 11) followed a worse clinical course than those with three or less imbalances (n = 5). The observation of similar genetic alterations in ETL and in primary gastric (n = 4) and colonic (n = 1) T-cell lymphoma, not otherwise specified, is suggestive of a genetic relationship of gastrointestinal T-cell lymphomas at either localization. PMID:12414511

Influence of Na and Ga on the electrical properties of perfect 60° dislocations in Cu(In, Ga)Se2 thin-film photovoltaic absorbers

NASA Astrophysics Data System (ADS)

Barragan-Yani, D.; Albe, K.

2018-04-01

The segregation of GaIn and NaCu to perfect 60° dislocations in CuIn1-xGaxSe2 is investigated by means of density functional theory calculations. We find that the segregation process is mainly driven by the elastic interaction of both defect types with the strain field of the dislocation. GaIn moves into the negatively strained region, while NaCu is found in the positively strained region. We show that both defects affect the electronic defect levels induced by the dislocation core and GaIn is able to passivate the β-core in CuInSe2. This result indicates that β-cores are inactive in CuIn1-xGaxSe2. NaCu; however, they do not have a significant effect on the electrical properties of the studied dislocation cores. Therefore, the experimentally observed sodium segregation to dislocation cores in CuIn1-xGaxSe2 cannot be considered as the passivation mechanism of the electrically active cores in that material.

African American and White women׳s perceptions of weight gain, physical activity, and nutrition during pregnancy.

PubMed

Whitaker, Kara M; Wilcox, Sara; Liu, Jihong; Blair, Steven N; Pate, Russell R

2016-03-01

To describe African American and White women's perceptions of weight gain, physical activity, and nutrition during pregnancy and to explore differences in perceptions by race. Qualitative interview study. Two Ob/Gyn clinics in South Carolina, USA. Thirty pregnant women (15 African American, 15 White) between 20 and 30 weeks gestation, equally represented across pre-pregnancy BMI categories (10 normal weight, 10 overweight, and 10 obese). White women more frequently described intentions to meet weight gain, physical activity, and dietary guidelines in pregnancy than African American women. African American women were more concerned with inadequate weight gain while White women more commonly expressed concerns about excessive weight gain. More White women discussed the importance of physical activity for weight management. Regardless of race, few women described risks of excessive weight gain or benefits of physical activity as it relates to the baby's health. The primary cited barrier of healthy eating was the high cost of fresh produce. Several knowledge gaps as well as race differences were identified in women's perceptions and intentions toward weight gain, physical activity, and nutrition during pregnancy. Future interventions should seek to educate women about common misperceptions. It may be necessary to culturally tailor gestational weight gain interventions to optimise health outcomes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Student learning style preferences in college-level biology courses: Implications for teaching and academic performance

NASA Astrophysics Data System (ADS)

Sitton, Jennifer Susan

Education research has focused on defining and identifying student learning style preferences and how to incorporate this knowledge into teaching practices that are effective in engaging student interest and transmitting information. One objective was determining the learning style preferences of undergraduate students in Biology courses at New Mexico State University by using the online VARK Questionnaire and an investigator developed survey (Self Assessed Learning Style Survey, LSS). Categories include visual, aural, read-write, kinesthetic, and multimodal. The courses differed in VARK single modal learning preferences (p = 0.035) but not in the proportions of the number of modes students preferred (p = 0.18). As elsewhere, the majority of students were multimodal. There were similarities and differences between LSS and VARK results and between students planning on attending medical school and those not. Preferences and modalities tended not to match as expected for ratings of helpfulness of images and text. To detect relationships between VARK preferred learning style and academic performance, ANOVAs were performed using modality preferences and normalized learning gains from pre and post tests over material taught in the different modalities, as well as on end of semester laboratory and lecture grades. Overall, preference did not affect the performance for a given modality based activity, quiz, or final lecture or laboratory grades (p > 0.05). This suggests that a student's preference does not predict an improved performance when supplied with material in that modality. It is recommended that methods be developed to aid learning in a variety of modalities, rather than catering to individual learning styles. Another topic that is heavily debated in the field of education is the use of simulations or videos to replace or supplement dissections. These activities were compared using normalized learning gains from pre and post tests, as well as attitude surveys. Results indicate no differences in average student learning gain based on the activity types tested, although students do rate dissections higher in terms of interest and enthusiasm. Dissections also offer a different type of learning. Therefore, it is suggested that simulations and videos be used as supplements for dissections and not as replacements.

Change in active transportation and weight gain in pregnancy.

PubMed

Skreden, Marianne; Øverby, Nina C; Sagedal, Linda R; Vistad, Ingvild; Torstveit, Monica K; Lohne-Seiler, Hilde; Bere, Elling

2016-01-27

Pregnancy is characterised by large weight gain over a short period, and often a notable change in mode of transportation. This makes pregnancy suitable for examining the plausible, but in the scientific literature still unclear, association between active transportation and weight gain. We hypothesize that women continuing an active mode of transportation to work or school from pre- to early pregnancy will have a lower gestational weight gain (GWG) than those who change to a less active mode of transportation. We analysed prospective data from the Norwegian Fit for Delivery (NFFD) trial. Between September 2009 and February 2013 606 women were consecutively enrolled in median gestational week 16 (range; 8-20). Of 219 women who used an active mode of transportation (biking, walking, public transportation) pre-pregnancy, 66 (30%) converted to a less active mode in early pregnancy ("active-less active" group), and 153 (70%) continued with active transportation ("active-active" group). Pre-pregnancy weight was self-reported. Weight at gestational (GA) weeks 16, 30, 36, and at term delivery was objectively measured. Weight gain was compared between the two groups. Linear mixed effects analysis of the repeated weight measures was performed including the group*time interaction. A significant overall group effect was observed for the four time points together ("active-active" group: 77.3 kg vs. "active-less active" group: 78.8 kg, p = 0.008). The interaction term group*time was significant indicating different weight gain throughout pregnancy for the two groups; the mean differences between the groups were 0.7 kg at week 16, 1.4 kg at week 30, 2.1 kg at week 36, and 2.2 kg at term delivery, respectively. The findings indicate that active transportation is one possible approach to prevent excessive weight gain in pregnancy.

Active control of acoustic pressure fields using smart material technologies

NASA Technical Reports Server (NTRS)

Banks, H. T.; Smith, R. C.

1993-01-01

An overview describing the use of piezoceramic patches in reducing noise in a structural acoustics setting is presented. The passive and active contributions due to patches which are bonded to an Euler-Bernoulli beam or thin shell are briefly discussed and the results are incorporated into a 2-D structural acoustics model. In this model, an exterior noise source causes structural vibrations which in turn lead to interior noise as a result of nonlinear fluid/structure coupling mechanism. Interior sound pressure levels are reduced via patches bonded to the flexible boundary (a beam in this case) which generate pure bending moments when an out-of-phase voltage is applied. Well-posedness results for the infinite dimensional system are discussed and a Galerkin scheme for approximating the system dynamics is outlined. Control is implemented by using linear quadratic regulator (LQR) optimal control theory to calculate gains for the linearized system and then feeding these gains back into the nonlinear system of interest. The effectiveness of this strategy for this problem is illustrated in an example.

Parametric amplification and bidirectional invisibility in PT -symmetric time-Floquet systems

NASA Astrophysics Data System (ADS)

Koutserimpas, Theodoros T.; Alù, Andrea; Fleury, Romain

2018-01-01

Parity-time (PT )-symmetric wave devices, which exploit balanced interactions between material gain and loss, exhibit extraordinary properties, including lasing and flux-conserving scattering processes. In a seemingly different research field, periodically driven systems, also known as time-Floquet systems, have been widely studied as a relevant platform for reconfigurable active wave control and manipulation. In this article, we explore the connection between PT -symmetry and parametric time-Floquet systems. Instead of relying on material gain, we use parametric amplification by considering a time-periodic modulation of the refractive index at a frequency equal to twice the incident signal frequency. We show that the scattering from a simple parametric slab, whose dynamics follows the Mathieu equation, can be described by a PT -symmetric scattering matrix, whose PT -breaking threshold corresponds to the Mathieu instability threshold. By combining different parametric slabs modulated out of phase, we create PT -symmetric time-Floquet systems that feature exceptional scattering properties, such as coherent perfect absorption (CPA)-laser operation and bidirectional invisibility. These bidirectional properties, rare for regular PT -symmetric systems, are related to a compensation of parametric amplification due to multiple scattering between two parametric systems modulated with a phase difference.

Intensity fluctuations in bimodal micropillar lasers enhanced by quantum-dot gain competition

NASA Astrophysics Data System (ADS)

Leymann, H. A. M.; Hopfmann, C.; Albert, F.; Foerster, A.; Khanbekyan, M.; Schneider, C.; Höfling, S.; Forchel, A.; Kamp, M.; Wiersig, J.; Reitzenstein, S.

2013-05-01

We investigate correlations between orthogonally polarized cavity modes of a bimodal micropillar laser with a single layer of self-assembled quantum dots in the active region. While one emission mode of the microlaser demonstrates a characteristic S-shaped input-output curve, the output intensity of the second mode saturates and even decreases with increasing injection current above threshold. Measuring the photon autocorrelation function g(2)(τ) of the light emission confirms the onset of lasing in the first mode with g(2)(0) approaching unity above threshold. In contrast, strong photon bunching associated with superthermal values of g(2)(0) is detected for the other mode for currents above threshold. This behavior is attributed to gain competition of the two modes induced by the common gain material, which is confirmed by photon cross-correlation measurements revealing a clear anticorrelation between emission events of the two modes. The experimental studies are in qualitative agreement with theoretical studies based on a microscopic semiconductor theory, which we extend to the case of two modes interacting with the common gain medium. Moreover, we treat the problem by a phenomenological birth-death model extended to two interacting modes, which reveals that the photon probability distribution of each mode has a double-peak structure, indicating switching behavior of the modes for pump rates around threshold.

Critical physiological factors influencing the outcome of antimicrobial testing according to ISO 22196 / JIS Z 2801.

PubMed

Wiegand, Cornelia; Völpel, Andrea; Ewald, Andrea; Remesch, Markko; Kuever, Jan; Bauer, Janine; Griesheim, Stefanie; Hauser, Carolin; Thielmann, Julian; Tonndorf-Martini, Silke; Sigusch, Bernd W; Weisser, Jürgen; Wyrwa, Ralf; Elsner, Peter; Hipler, Uta-Christina; Roth, Martin; Dewald, Carolin; Lüdecke-Beyer, Claudia; Bossert, Jörg

2018-01-01

Bactericidal materials gained interest in the health care sector as they are capable of preventing material surfaces from microbial colonization and subsequent spread of infections. However, commercialization of antimicrobial materials requires proof of their efficacy, which is usually done using in vitro methods. The ISO 22196 standard (Japanese test method JIS Z 2801) is a method for measuring the antibacterial activity of daily goods. As it was found reliable for testing the biocidal activity of antimicrobially active materials and surface coatings most of the laboratories participating in this study used this protocol. Therefore, a round robin test for evaluating antimicrobially active biomaterials had to be established. To our knowledge, this is the first report on inaugurating a round robin test for the ISO 22196 / JIS Z 2801. The first round of testing showed that analyses in the different laboratories yielded different results, especially for materials with intermediate antibacterial effects distinctly different efficacies were noted. Scrutinizing the protocols used by the different participants and identifying the factors influencing the test outcomes the approach was unified. Four critical factors influencing the outcome of antibacterial testing were identified in a series of experiments: (1) incubation time, (2) bacteria starting concentration, (3) physiological state of bacteria (stationary or exponential phase of growth), and (4) nutrient concentration. To our knowledge, this is the first time these parameters have been analyzed for their effect on the outcome of testing according to ISO 22196 / JIS Z 2801. In conclusion, to enable assessment of the results obtained it is necessary to evaluate these single parameters in the test protocol carefully. Furthermore, uniform and robust definitions of the terms antibacterial efficacy / activity, bacteriostatic effects, and bactericidal action need to be agreed upon to simplify communication of results and also regulate expectations regarding antimicrobial tests, outcomes, and materials.

Critical physiological factors influencing the outcome of antimicrobial testing according to ISO 22196 / JIS Z 2801

PubMed Central

Völpel, Andrea; Ewald, Andrea; Remesch, Markko; Kuever, Jan; Bauer, Janine; Griesheim, Stefanie; Hauser, Carolin; Thielmann, Julian; Tonndorf-Martini, Silke; Sigusch, Bernd W.; Weisser, Jürgen; Wyrwa, Ralf; Elsner, Peter; Hipler, Uta-Christina; Roth, Martin; Dewald, Carolin; Lüdecke-Beyer, Claudia; Bossert, Jörg

2018-01-01

Bactericidal materials gained interest in the health care sector as they are capable of preventing material surfaces from microbial colonization and subsequent spread of infections. However, commercialization of antimicrobial materials requires proof of their efficacy, which is usually done using in vitro methods. The ISO 22196 standard (Japanese test method JIS Z 2801) is a method for measuring the antibacterial activity of daily goods. As it was found reliable for testing the biocidal activity of antimicrobially active materials and surface coatings most of the laboratories participating in this study used this protocol. Therefore, a round robin test for evaluating antimicrobially active biomaterials had to be established. To our knowledge, this is the first report on inaugurating a round robin test for the ISO 22196 / JIS Z 2801. The first round of testing showed that analyses in the different laboratories yielded different results, especially for materials with intermediate antibacterial effects distinctly different efficacies were noted. Scrutinizing the protocols used by the different participants and identifying the factors influencing the test outcomes the approach was unified. Four critical factors influencing the outcome of antibacterial testing were identified in a series of experiments: (1) incubation time, (2) bacteria starting concentration, (3) physiological state of bacteria (stationary or exponential phase of growth), and (4) nutrient concentration. To our knowledge, this is the first time these parameters have been analyzed for their effect on the outcome of testing according to ISO 22196 / JIS Z 2801. In conclusion, to enable assessment of the results obtained it is necessary to evaluate these single parameters in the test protocol carefully. Furthermore, uniform and robust definitions of the terms antibacterial efficacy / activity, bacteriostatic effects, and bactericidal action need to be agreed upon to simplify communication of results and also regulate expectations regarding antimicrobial tests, outcomes, and materials. PMID:29558480

Electrochemical impedance spectroscopy system and methods for determining spatial locations of defects

DOEpatents

Glenn, David F.; Matthern, Gretchen E.; Propp, W. Alan; Glenn, Anne W.; Shaw, Peter G.

2006-08-08

A method and apparatus for determining spatial locations of defects in a material are described. The method includes providing a plurality of electrodes in contact with a material, applying a sinusoidal voltage to a select number of the electrodes at a predetermined frequency, determining gain and phase angle measurements at other of the electrodes in response to applying the sinusoidal voltage to the select number of electrodes, determining impedance values from the gain and phase angle measurements, computing an impedance spectrum for an area of the material from the determined impedance values, and comparing the computed impedance spectrum with a known impedance spectrum to identify spatial locations of defects in the material.

Electric fish as natural models for technical sensor systems

NASA Astrophysics Data System (ADS)

von der Emde, Gerhard; Bousack, Herbert; Huck, Christina; Mayekar, Kavita; Pabst, Michael; Zhang, Yi

2009-05-01

Instead of vision, many animals use alternative senses for object detection. Weakly electric fish employ "active electrolocation", during which they discharge an electric organ emitting electrical current pulses (electric organ discharges, EOD). Local EODs are sensed by electroreceptors in the fish's skin, which respond to changes of the signal caused by nearby objects. Fish can gain information about attributes of an object, such as size, shape, distance, and complex impedance. When close to the fish, each object projects an 'electric image' onto the fish's skin. In order to get information about an object, the fish has to analyze the object's electric image by sampling its voltage distribution with the electroreceptors. We now know a great deal about the mechanisms the fish use to gain information about objects in their environment. Inspired by the remarkable capabilities of weakly electric fish in detecting and recognizing objects with their electric sense, we are designing technical sensor systems that can solve similar sensing problems. We applied the principles of active electrolocation to devices that produce electrical current pulses in water and simultaneously sense local current densities. Depending on the specific task, sensors can be designed which detect an object, localize it in space, determine its distance, and measure certain object properties such as material properties, thickness, or material faults. We present first experiments and FEM simulations on the optimal sensor arrangement regarding the sensor requirements e. g. localization of objects or distance measurements. Different methods of the sensor read-out and signal processing are compared.

High-Power Fiber Lasers Using Photonic Band Gap Materials

NASA Technical Reports Server (NTRS)

DiDomenico, Leo; Dowling, Jonathan

2005-01-01

High-power fiber lasers (HPFLs) would be made from photonic band gap (PBG) materials, according to the proposal. Such lasers would be scalable in the sense that a large number of fiber lasers could be arranged in an array or bundle and then operated in phase-locked condition to generate a superposition and highly directed high-power laser beam. It has been estimated that an average power level as high as 1,000 W per fiber could be achieved in such an array. Examples of potential applications for the proposed single-fiber lasers include welding and laser surgery. Additionally, the bundled fibers have applications in beaming power through free space for autonomous vehicles, laser weapons, free-space communications, and inducing photochemical reactions in large-scale industrial processes. The proposal has been inspired in part by recent improvements in the capabilities of single-mode fiber amplifiers and lasers to produce continuous high-power radiation. In particular, it has been found that the average output power of a single strand of a fiber laser can be increased by suitably changing the doping profile of active ions in its gain medium to optimize the spatial overlap of the electromagnetic field with the distribution of active ions. Such optimization minimizes pump power losses and increases the gain in the fiber laser system. The proposal would expand the basic concept of this type of optimization to incorporate exploitation of the properties (including, in some cases, nonlinearities) of PBG materials to obtain power levels and efficiencies higher than are now possible. Another element of the proposal is to enable pumping by concentrated sunlight. Somewhat more specifically, the proposal calls for exploitation of the properties of PBG materials to overcome a number of stubborn adverse phenomena that have impeded prior efforts to perfect HPFLs. The most relevant of those phenomena is amplified spontaneous emission (ASE), which causes saturation of gain and power at undesirably low levels, and scattering of light from dopants. In designing a given fiber laser for reduced ASE, care must be taken to maintain a correct fiber structure for eventual scaling to an array of many such lasers such that the interactions among all the members of the array would cause them to operate in phase lock. Hence, the problems associated with improving a single-fiber laser are not entirely separate from the bundling problem, and some designs for individual fiber lasers may be better than others if the fibers are to be incorporated into bundles. Extensive calculations, expected to take about a year, must be performed in order to determine design parameters before construction of prototype individual and fiber lasers can begin. The design effort can be expected to include calculations to optimize overlaps between the electromagnetic modes and the gain media and calculations of responses of PBG materials to electromagnetic fields. Design alternatives and physical responses that may be considered include simple PBG fibers with no intensity-dependent responses, PBG fibers with intensity- dependent band-gap shifting (see figure), and broad-band pumping made possible by use of candidate broad-band pumping media in place of the air or vacuum gaps used in prior PBG fibers.

20 CFR 416.971 - General.

Code of Federal Regulations, 2010 CFR

2010-04-01

... you are able to work at the substantial gainful activity level. If you are able to engage in substantial gainful activity, we will find that you are not disabled. (We explain the rules for persons who... Determining Disability and Blindness Substantial Gainful Activity § 416.971 General. The work, without regard...

20 CFR 404.1571 - General.

Code of Federal Regulations, 2011 CFR

2011-04-01

... you are able to work at the substantial gainful activity level. If you are able to engage in substantial gainful activity, we will find that you are not disabled. (We explain the rules for persons who...- ) Determining Disability and Blindness Substantial Gainful Activity § 404.1571 General. The work, without regard...

20 CFR 404.1571 - General.

Code of Federal Regulations, 2010 CFR

2010-04-01

... you are able to work at the substantial gainful activity level. If you are able to engage in substantial gainful activity, we will find that you are not disabled. (We explain the rules for persons who...- ) Determining Disability and Blindness Substantial Gainful Activity § 404.1571 General. The work, without regard...

20 CFR 220.143 - Evaluation guides for an employed claimant.

Code of Federal Regulations, 2010 CFR

2010-04-01

... would not determine that the person worked at the substantial gainful activity level only on the basis... RETIREMENT ACT DETERMINING DISABILITY Substantial Gainful Activity § 220.143 Evaluation guides for an... done shows that he or she is able to do substantial gainful activity. (1) The claimant's earnings may...

20 CFR 404.1574a - When and how we will average your earnings.

Code of Federal Regulations, 2011 CFR

2011-04-01

... has been no change in the substantial gainful activity earnings levels, we will average your earnings... time during which the substantial gainful activity earnings levels change, we will average your earnings separately for each period in which a different substantial gainful activity earnings level...

20 CFR 416.971 - General.

Code of Federal Regulations, 2011 CFR

2011-04-01

... you are able to work at the substantial gainful activity level. If you are able to engage in substantial gainful activity, we will find that you are not disabled. (We explain the rules for persons who... Determining Disability and Blindness Substantial Gainful Activity § 416.971 General. The work, without regard...

20 CFR 404.1574a - When and how we will average your earnings.

Code of Federal Regulations, 2010 CFR

2010-04-01

... has been no change in the substantial gainful activity earnings levels, we will average your earnings... time during which the substantial gainful activity earnings levels change, we will average your earnings separately for each period in which a different substantial gainful activity earnings level...

20 CFR 220.143 - Evaluation guides for an employed claimant.

Code of Federal Regulations, 2011 CFR

2011-04-01

... would not determine that the person worked at the substantial gainful activity level only on the basis... RETIREMENT ACT DETERMINING DISABILITY Substantial Gainful Activity § 220.143 Evaluation guides for an... done shows that he or she is able to do substantial gainful activity. (1) The claimant's earnings may...

20 CFR 229.85 - Substantial gainful activity by blind employee or child.

Code of Federal Regulations, 2010 CFR

2010-04-01

... THE RAILROAD RETIREMENT ACT SOCIAL SECURITY OVERALL MINIMUM GUARANTEE Miscellaneous Deductions and... substantial gainful activity that does not require skills or ability used in his or her previous work. However... in any type of substantial gainful activity which requires skills or abilities comparable to those of...

A Pilot Study for Gainful Employment in Home Economics. Final Report. Volume I.

ERIC Educational Resources Information Center

Cozine, June; And Others

The major purpose of the study was to develop and test curriculum materials for three entry level gainful employment courses: Child Care Services, Clothing Services, Food Services. A second objective was to formulate recommendations for policies and procedures to follow in initiating and developing gainful employment programs in home economics.…

Resolved discrepancies between visible spontaneous Raman cross-section and direct near-infrared Raman gain measurements in TeO2-based glasses.

PubMed

Rivero, Clara; Stegeman, Robert; Couzi, Michel; Talaga, David; Cardinal, Thierry; Richardson, Kathleen; Stegeman, George

2005-06-13

Disagreements on the Raman gain response of different tellurite-based glasses, measured at different wavelengths, have been recently reported in the literature. In order to resolve this controversy, a multi-wavelength Raman cross-section experiment was conducted on two different TeO2-based glass samples. The estimated Raman gain response of the material shows good agreement with the directly-measured Raman gain data at 1064 nm, after correction for the dispersion and wavelength-dependence of the Raman gain process.

Accumulated distribution of material gain at dislocation crystal growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rakin, V. I., E-mail: rakin@geo.komisc.ru

2016-05-15

A model for slowing down the tangential growth rate of an elementary step at dislocation crystal growth is proposed based on the exponential law of impurity particle distribution over adsorption energy. It is established that the statistical distribution of material gain on structurally equivalent faces obeys the Erlang law. The Erlang distribution is proposed to be used to calculate the occurrence rates of morphological combinatorial types of polyhedra, presenting real simple crystallographic forms.

Nicotine Replacement: Effects on Postcessation Weight Gain.

ERIC Educational Resources Information Center

Gross, Janet; And Others

1989-01-01

Examined nicotine replacement effects on postcessation weight gain in smoking cessation volunteers. Randomly assigned abstinent subjects to active nicotine or placebo gum conditions for 10 weeks. Analyses revealed strong evidence for gum effect on weight gain, with active gum users gaining mean total of 3.8 pounds compared with 7.8 pounds for…

Perovskite- and Heusler based materials for thermoelectric converters

NASA Astrophysics Data System (ADS)

Weidenkaff, Anke

2015-03-01

The broad application of thermoelectric converters in future energy technologies requires the development of active, stable, low cost and sustainable materials. Semiconductors based on perovskite and heusler structures show substantial potential for thermoelectric energy conversion processes. Their good performance can be explained based on their suitable band structure, adjusted charge carrier density, mass and mobility, limited phonon transport, electron filtering possibilities, strongly correlated electronic systems, etc. These properties are widely tuneable by following theoretical concepts and a deep composition-structure-property understanding to change the composition, structure and size of the crystallites in innovative scalable synthesis procedures. Improved thermoelectric materials are developed, synthesised and tested in diverse high temperature applications to improve the efficiency and energy density of the thermoelectric conversion process. The lecture will provide a summary on the field of advanced perovskite-type ceramics and Heusler compounds gaining importance for a large number of future energy technologies.

Early implementation of SiC cladding fuel performance models in BISON

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powers, Jeffrey J.

2015-09-18

SiC-based ceramic matrix composites (CMCs) [5–8] are being developed and evaluated internationally as potential LWR cladding options. These development activities include interests within both the DOE-NE LWR Sustainability (LWRS) Program and the DOE-NE Advanced Fuels Campaign. The LWRS Program considers SiC ceramic matrix composites (CMCs) as offering potentially revolutionary gains as a cladding material, with possible benefits including more efficient normal operating conditions and higher safety margins under accident conditions [9]. Within the Advanced Fuels Campaign, SiC-based composites are a candidate ATF cladding material that could achieve several goals, such as reducing the rates of heat and hydrogen generation duemore » to lower cladding oxidation rates in HT steam [10]. This work focuses on the application of SiC cladding as an ATF cladding material in PWRs, but these work efforts also support the general development and assessment of SiC as an LWR cladding material in a much broader sense.« less

Safe transport of radioactive materials in Egypt

NASA Astrophysics Data System (ADS)

El-Shinawy, Rifaat M. K.

1994-07-01

In Egypt the national regulations for safe transport of radioactive materials (RAM) are based on the International Atomic Energy Agency (IAEA) regulations. In addition, regulations for the safe transport of these materials through the Suez Canal (SC) were laid down by the Egyptian Atomic Energy Authority (EAEA) and the Suez Canal Authority (SCA). They are continuously updated to meet the increased knowledge and the gained experience. The technical and protective measures taken during transport of RAM through SC are mentioned. Assessment of the impact of transporting radioactive materials through the Suez Canal using the INTERTRAN computer code was carried out in cooperation with IAEA. The transported activities and empty containers, the number of vessels carrying RAM through the canal from 1963 to 1991 and their nationalities are also discussed. The protective measures are mentioned.A review of the present situation of the radioactive wastes storage facilities at the Atomic Energy site at Inshas is given along with the regulation for safe transportation and disposal of radioactive wastes

The effects of test-enhanced learning on long-term retention in AAN annual meeting courses.

PubMed

Larsen, Douglas P; Butler, Andrew C; Aung, Wint Y; Corboy, John R; Friedman, Deborah I; Sperling, Michael R

2015-02-17

We measured the long-term retention of knowledge gained through selected American Academy of Neurology annual meeting courses and compared the effects of repeated quizzing (known as test-enhanced learning) and repeated studying on that retention. Participants were recruited from 4 annual meeting courses. All participants took a pretest. This randomized, controlled trial utilized a within-subjects design in which each participant experienced 3 different postcourse activities with each activity performed on different material. Each key information point from the course was randomized in a counterbalanced fashion among participants to one of the 3 activities: repeated short-answer quizzing, repeated studying, and no further exposure to the materials. A final test covering all information points from the course was taken 5.5 months after the course. Thirty-five participants across the 4 courses completed the study. Average score on the pretest was 36%. Performance on the final test showed that repeated quizzing led to significantly greater long-term retention relative to both repeated studying (55% vs 46%; t[34] = 3.28, SEM = 0.03, p = 0.01, d = 0.49) and no further exposure (55% vs 44%; t[34] = 3.16, SEM = 0.03, p = 0.01, d = 0.58). Relative to the pretest baseline, repeated quizzing helped participants to retain almost twice as much of the knowledge acquired from the course compared to repeated studying or no further exposure. Whereas annual meeting continuing medical education (CME) courses lead to long-term gains in knowledge, when repeated quizzing is added, retention is significantly increased. CME planners may consider adding repeated quizzing to increase the impact of their courses. © 2015 American Academy of Neurology.

The effects of test-enhanced learning on long-term retention in AAN annual meeting courses

PubMed Central

Butler, Andrew C.; Aung, Wint Y.; Corboy, John R.; Friedman, Deborah I.; Sperling, Michael R.

2015-01-01

Objective: We measured the long-term retention of knowledge gained through selected American Academy of Neurology annual meeting courses and compared the effects of repeated quizzing (known as test-enhanced learning) and repeated studying on that retention. Methods: Participants were recruited from 4 annual meeting courses. All participants took a pretest. This randomized, controlled trial utilized a within-subjects design in which each participant experienced 3 different postcourse activities with each activity performed on different material. Each key information point from the course was randomized in a counterbalanced fashion among participants to one of the 3 activities: repeated short-answer quizzing, repeated studying, and no further exposure to the materials. A final test covering all information points from the course was taken 5.5 months after the course. Results: Thirty-five participants across the 4 courses completed the study. Average score on the pretest was 36%. Performance on the final test showed that repeated quizzing led to significantly greater long-term retention relative to both repeated studying (55% vs 46%; t[34] = 3.28, SEM = 0.03, p = 0.01, d = 0.49) and no further exposure (55% vs 44%; t[34] = 3.16, SEM = 0.03, p = 0.01, d = 0.58). Relative to the pretest baseline, repeated quizzing helped participants to retain almost twice as much of the knowledge acquired from the course compared to repeated studying or no further exposure. Conclusions: Whereas annual meeting continuing medical education (CME) courses lead to long-term gains in knowledge, when repeated quizzing is added, retention is significantly increased. CME planners may consider adding repeated quizzing to increase the impact of their courses. PMID:25609761

Inorganic polymers from laterite using activation with phosphoric acid and alkaline sodium silicate solution: Mechanical and microstructural properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lassinantti Gualtieri, Magdalena, E-mail: magdalena.gualtieri@unimore.it; Romagnoli, Marcello; Pollastri, Simone

2015-01-15

Geopolymers from laterite, an iron-rich soil available in developing countries, have great potential as building materials. In this work, laterite from Togo (Africa) was used to prepare geopolymers using both phosphoric acid and alkaline sodium silicate solution. Microstructural properties were investigated by scanning electron microscopy, X-ray powder diffraction and mercury porosimetry, whereas thermal properties were evaluated by thermal analyses. The local environment of iron was studied by X-ray Absorption Spectroscopy (XANES region). The mechanical properties were determined. Modulus of Rupture and Young's modulus fell in the ranges 3.3–4.5 MPa and 12–33 GPa, respectively, rendering the materials good candidates for constructionmore » purposes. Heating above 900 °C results in weight-gain, presumably due to iron redox reactions. X-ray Absorption Spectroscopy data evidence changes in the chemical and structural environments of iron following thermal treatment of geopolymers. These changes indicate interaction between the geopolymer structure and iron during heating, possibly leading to redox properties. -- Highlights: •Geopolymerization of laterite is promising for fabrication of building materials. •Both phosphoric acid and alkaline sodium silicate solution can be used for activation. •Thermally activated redox properties of the inorganic polymers were observed.« less

[Influence of cutting seedling on growth, quality and yield of both aerial and underground part by cutting seedling in Scutellaria baicalensis].

PubMed

Liu, Rong-Xiu; Li, Yong-Jie; Li, Lin; Miao, Xiao-Su; Wang, Xue-Sen; Zhang, Dan; Wei, Sheng-Li

2016-06-01

By measuring the growth data of Scutellaria baicalensis in different cutting-seedling and determined active ingredient contents by HPLC and ultraviolet spectrophotometric determination. such as flavonoids. baicalin. wogonoside. baicalein. wogonin. oroxylin A. scutellarin. luteolin. and apigenin in the whole plant. Under circumstances of guaranteeing the quality and yield of medicinal materials. the yield of medicinal materials. and stems and leaves reached 193.60,63.21 kg/mu after twice cutting seedling. Not only yield but also active ingredient contents have been improved to some extent. the contents of flavonoids. baicalin. wogonoside. baicalein. wogonin. oroxylin A reached 18.52%. 15.13%. 4.03%. 1.04%. 1.04%. 0.12%. respectively in roots. Luteolin was not detected in young stems and leaves of S. baicalensis,the contents of other active ingredients such as scutellarin. luteolin and apigenin reached 7.00%. 0.96%. 0.04% respectively under twice cutting seedling. Therefore. regular cutting seedling could be regard as a new cultivation technique for wider range of promotion. And gaining high quality and yield of medicinal materials and tea with the purpose of rational utilization of natural resources and promoting the development of integration of herbal combination. Copyright© by the Chinese Pharmaceutical Association.

Potential Underlying Mechanisms for Greater Weight Gain in Massaged Preterm Infants

PubMed Central

Field, Tiffany; Diego, Miguel; Hernandez-Reif, Maria

2010-01-01

In this paper, potential underlying mechanisms for massage therapy effects on preterm infant weight gain are reviewed. Path analyses are presented suggesting that: 1) increased vagal activity was associated with 2) increased gastric motility, which, in turn, was related to 3) greater weight gain; and 4) increased IGF-1 was related to greater weight gain. The change in vagal activity during the massage explained 49% of the variance in the change in gastric activity. And, the change in vagal activity during the massage explained 62% of the variance in the change in insulin. That the change in gastric activity was not related to the change in insulin suggests two parallel pathways via which massage therapy leads to increased weight gain: 1) insulin release via the celiac branch of the vagus; and 2) increased gastric activity via the gastric branch of the vagus. PMID:21570125

Role of RGO support and irradiation source on the photocatalytic activity of CdS–ZnO semiconductor nanostructures

PubMed Central

Kumar, Suneel; Sharma, Rahul; Sharma, Vipul; Harith, Gurunarayanan; Sivakumar, Vaidyanathan

2016-01-01

Photocatalytic activity of semiconductor nanostructures is gaining much importance in recent years in both energy and environmental applications. However, several parameters play a crucial role in enhancing or suppressing the photocatalytic activity through, for example, modifying the band gap energy positions, influencing the generation and transport of charge carriers and altering the recombination rate. In this regard, physical parameters such as the support material and the irradiation source can also have significant effect on the activity of the photocatalysts. In this work, we have investigated the role of reduced graphene oxide (RGO) support and the irradiation source on mixed metal chalcogenide semiconductor (CdS–ZnO) nanostructures. The photocatalyst material was synthesized using a facile hydrothermal method and thoroughly characterized using different spectroscopic and microscopic techniques. The photocatalytic activity was evaluated by studying the degradation of a model dye (methyl orange, MO) under visible light (only) irradiation and under natural sunlight. The results reveal that the RGO-supported CdS–ZnO photocatalyst performs considerably better than the unsupported CdS–ZnO nanostructures. In addition, both the catalysts perform significantly better under natural sunlight than under visible light (only) irradiation. In essence, this work paves way for tailoring the photocatalytic activity of semiconductor nanostructures. PMID:28144518

Influence of compact disk recording protocols on reliability and comparability of speech audiometry outcomes: acoustic analysis.

PubMed

Di Berardino, F; Tognola, G; Paglialonga, A; Alpini, D; Grandori, F; Cesarani, A

2010-08-01

To assess whether different compact disk recording protocols, used to prepare speech test material, affect the reliability and comparability of speech audiometry testing. We conducted acoustic analysis of compact disks used in clinical practice, to determine whether speech material had been recorded using similar procedures. To assess the impact of different recording procedures on speech test outcomes, normal hearing subjects were tested using differently prepared compact disks, and their psychometric curves compared. Acoustic analysis revealed that speech material had been recorded using different protocols. The major difference was the gain between the levels at which the speech material and the calibration signal had been recorded. Although correct calibration of the audiometer was performed for each compact disk before testing, speech recognition thresholds and maximum intelligibility thresholds differed significantly between compact disks (p < 0.05), and were influenced by the gain between the recording level of the speech material and the calibration signal. To ensure the reliability and comparability of speech test outcomes obtained using different compact disks, it is recommended to check for possible differences in the recording gains used to prepare the compact disks, and then to compensate for any differences before testing.

Assessing Student Learning about the Earth through the InTeGrate Project

NASA Astrophysics Data System (ADS)

Gilbert, L. A.; Iverson, E. A. R.; Steer, D. N.; Birnbaum, S. J.; Manduca, C. A.

2016-12-01

InTeGrate, a five-year community-based project comprised of faculty in the sciences and other disciplines, educational specialists, and evaluation experts at diverse institutions, instills learning about Earth in the context of societal issues through teaching materials developed into 2-3 week modules or courses. Materials were tested by over 135 materials authors and faculty interested in using these materials in undergraduate courses at a range of institution types across the US in geoscience, engineering, humanities, and social science courses. To assess impact on student learning, the InTeGrate project has collected student work from over 4,600 students enrolled in courses using these materials. To evaluate the influence of the materials on learning gains related to geoscience literacy, a set of 8 multiple choice items were developed, tested, and then administered in the first and last week of class in approximately 180 courses. The items were developed by 14 community members with assessment expertise and address content and concepts in the Earth, Climate, Atmosphere, and Ocean Science literacy documents. In a sample of 2,023 paired first and last week responses, students exhibit a 10% normalized gain (equivalent to 1 point of a 12 point total) regardless of their initial score. Students in the lowest quartile at the beginning of the course demonstrate the highest gains (4th quartile gain of 1.8) versus the higher quartile where a ceiling effect is present. In addition, a free-response essay was administered in the last week of the course which tests students' understanding for how Earth system interactions influence people's ability to make decisions about global societal challenges. Analysis of these essays demonstrates a strong relationship between the InTeGrate content and the subject matter of the student essay. These preliminary findings suggest that the use of InTeGrate materials increases students' understanding of geoscience literacies and the materials give students a topical hook for connecting learning about Earth to societal challenges.

20 CFR 229.85 - Substantial gainful activity by blind employee or child.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false Substantial gainful activity by blind employee or child. 229.85 Section 229.85 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER... Reductions § 229.85 Substantial gainful activity by blind employee or child. A blind employee or child who is...

20 CFR 229.85 - Substantial gainful activity by blind employee or child.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true Substantial gainful activity by blind employee or child. 229.85 Section 229.85 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE... § 229.85 Substantial gainful activity by blind employee or child. A blind employee or child who is 55...

20 CFR 229.85 - Substantial gainful activity by blind employee or child.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true Substantial gainful activity by blind employee or child. 229.85 Section 229.85 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE... § 229.85 Substantial gainful activity by blind employee or child. A blind employee or child who is 55...

Carbon Nanotubes for Human Space Flight

NASA Technical Reports Server (NTRS)

Scott, Carl D.; Files, Brad; Yowell, Leonard

2003-01-01

Single-wall carbon nanotubes offer the promise of a new class of revolutionary materials for space applications. The Carbon Nanotube Project at NASA Johnson Space Center has been actively researching this new technology by investigating nanotube production methods (arc, laser, and HiPCO) and gaining a comprehensive understanding of raw and purified material using a wide range of characterization techniques. After production and purification, single wall carbon nanotubes are processed into composites for the enhancement of mechanical, electrical, and thermal properties. This "cradle-to-grave" approach to nanotube composites has given our team unique insights into the impact of post-production processing and dispersion on the resulting material properties. We are applying our experience and lessons-learned to developing new approaches toward nanotube material characterization, structural composite fabrication, and are also making advances in developing thermal management materials and electrically conductive materials in various polymer-nanotube systems. Some initial work has also been conducted with the goal of using carbon nanotubes in the creation of new ceramic materials for high temperature applications in thermal protection systems. Human space flight applications such as advanced life support and fuel cell technologies are also being investigated. This discussion will focus on the variety of applications under investigation.

Elementary Students' Learning of Materials Science Practices Through Instruction Based on Engineering Design Tasks

NASA Astrophysics Data System (ADS)

Wendell, Kristen Bethke; Lee, Hee-Sun

2010-12-01

Materials science, which entails the practices of selecting, testing, and characterizing materials, is an important discipline within the study of matter. This paper examines how third grade students' materials science performance changes over the course of instruction based on an engineering design challenge. We conducted a case study of nine students who participated in engineering design-based science instruction with the goal of constructing a stable, quiet, thermally comfortable model house. The learning outcome of materials science practices was assessed by clinical interviews conducted before and after the instruction, and the learning process was assessed by students' workbooks completed during the instruction. The interviews included two materials selection tasks for designing a sturdy stepstool and an insulated pet habitat. Results indicate that: (1) students significantly improved on both materials selection tasks, (2) their gains were significantly positively associated with the degree of completion of their workbooks, and (3) students who were highly engaged with the workbook's reflective record-keeping tasks showed the greatest improvement on the interviews. These findings suggest the important role workbooks can play in facilitating elementary students' learning of science through authentic activity such as engineering design.

Low dose digital X-ray imaging with avalanche amorphous selenium

NASA Astrophysics Data System (ADS)

Scheuermann, James R.; Goldan, Amir H.; Tousignant, Olivier; Léveillé, Sébastien; Zhao, Wei

2015-03-01

Active Matrix Flat Panel Imagers (AMFPI) based on an array of thin film transistors (TFT) have become the dominant technology for digital x-ray imaging. In low dose applications, the performance of both direct and indirect conversion detectors are limited by the electronic noise associated with the TFT array. New concepts of direct and indirect detectors have been proposed using avalanche amorphous selenium (a-Se), referred to as high gain avalanche rushing photoconductor (HARP). The indirect detector utilizes a planar layer of HARP to detect light from an x-ray scintillator and amplify the photogenerated charge. The direct detector utilizes separate interaction (non-avalanche) and amplification (avalanche) regions within the a-Se to achieve depth-independent signal gain. Both detectors require the development of large area, solid state HARP. We have previously reported the first avalanche gain in a-Se with deposition techniques scalable to large area detectors. The goal of the present work is to demonstrate the feasibility of large area HARP fabrication in an a-Se deposition facility established for commercial large area AMFPI. We also examine the effect of alternative pixel electrode materials on avalanche gain. The results show that avalanche gain > 50 is achievable in the HARP layers developed in large area coaters, which is sufficient to achieve x-ray quantum noise limited performance down to a single x-ray photon per pixel. Both chromium (Cr) and indium tin oxide (ITO) have been successfully tested as pixel electrodes.

Preparation of active antibacterial LDPE surface through multistep physicochemical approach: I. Allylamine grafting, attachment of antibacterial agent and antibacterial activity assessment.

PubMed

Bílek, František; Křížová, Táňa; Lehocký, Marián

2011-11-01

Low-density polyethylene (LDPE) samples were treated in air plasma discharge, coated by polyallyamine brush thought copolymeric grafting surface-from reaction and deposited four common antibacterial agents (benzalkonium chloride, bronopol, chlorhexidine and triclosan) to gain material with active antibacterial properties. Surface characteristics were evaluated by static contact angle measurement with surface energy evaluation ATR-FTIR, X-ray Photoelectron Spectroscopy (XPS) and SEM analysis. Inhibition zone on agar was used as in vitro test of antibacterial properties on two representative gram positive Staphylococcus aureus (S. aureus) and gram negative Escherichia coli (E. coli) strains. It was confirmed, that after grafting of polyallyamine, more antibacterial agent is immobilized on the surface. The highest increase of antibacterial activity was observed by the sample containing triclosan. Samples covered by bronopol did not show significant antibacterial activity. Copyright © 2011 Elsevier B.V. All rights reserved.

Blocking rapid ice crystal growth through nonbasal plane adsorption of antifreeze proteins

PubMed Central

Olijve, Luuk L. C.; Meister, Konrad; DeVries, Arthur L.; Duman, John G.; Guo, Shuaiqi; Bakker, Huib J.; Voets, Ilja K.

2016-01-01

Antifreeze proteins (AFPs) are a unique class of proteins that bind to growing ice crystal surfaces and arrest further ice growth. AFPs have gained a large interest for their use in antifreeze formulations for water-based materials, such as foods, waterborne paints, and organ transplants. Instead of commonly used colligative antifreezes such as salts and alcohols, the advantage of using AFPs as an additive is that they do not alter the physicochemical properties of the water-based material. Here, we report the first comprehensive evaluation of thermal hysteresis (TH) and ice recrystallization inhibition (IRI) activity of all major classes of AFPs using cryoscopy, sonocrystallization, and recrystallization assays. The results show that TH activities determined by cryoscopy and sonocrystallization differ markedly, and that TH and IRI activities are not correlated. The absence of a distinct correlation in antifreeze activity points to a mechanistic difference in ice growth inhibition by the different classes of AFPs: blocking fast ice growth requires rapid nonbasal plane adsorption, whereas basal plane adsorption is only relevant at long annealing times and at small undercooling. These findings clearly demonstrate that biomimetic analogs of antifreeze (glyco)proteins should be tailored to the specific requirements of the targeted application. PMID:26936953

Capillary-induced crack healing between surfaces of nanoscale roughness.

PubMed

Soylemez, Emrecan; de Boer, Maarten P

2014-10-07

Capillary forces are important in nature (granular materials, insect locomotion) and in technology (disk drives, adhesion). Although well studied in equilibrium state, the dynamics of capillary formation merit further investigation. Here, we show that microcantilever crack healing experiments are a viable experimental technique for investigating the influence of capillary nucleation on crack healing between rough surfaces. The average crack healing velocity, v̅, between clean hydrophilic polycrystalline silicon surfaces of nanoscale roughness is measured. A plot of v̅ versus energy release rate, G, reveals log-linear behavior, while the slope |d[log(v̅)]/dG| decreases with increasing relative humidity. A simplified interface model that accounts for the nucleation time of water bridges by an activated process is developed to gain insight into the crack healing trends. This methodology enables us to gain insight into capillary bridge dynamics, with a goal of attaining a predictive capability for this important microelectromechanical systems (MEMS) reliability failure mechanism.

Persistence or Change in Leisure-Time Physical Activity Habits and Waist Gain During Early Adulthood: A Twin-Study

PubMed Central

Rottensteiner, Mirva; Pietiläinen, Kirsi H.; Kaprio, Jaakko; Kujala, Urho M.

2014-01-01

Objective To determine the relationship between persistence or change in leisure-time physical activity habits and waist gain among young adults. Design and Methods Population-based cohort study among 3383 Finnish twin individuals (1578 men) from five birth cohorts (1975–1979), who answered questionnaires at mean ages of 24.4 y (SD 0.9) and 33.9 y (SD 1.2), with reported self-measured waist circumference. Persistence or change in leisure-time physical activity habits was defined based on thirds of activity metabolic equivalent h/day during follow-up (mean 9.5 y; SD 0.7). Results Decreased activity was linked to greater waist gain compared to increased activity (3.6 cm, P<0.001 for men; 3.1 cm, P<0.001 for women). Among same-sex activity discordant twin pairs, twins who decreased activity gained an average 2.8 cm (95%CI 0.4 to 5.1, P=0.009) more waist than their co-twins who increased activity (n=85 pairs); among MZ twin pairs (n=43), the difference was 4.2 cm (95%CI 1.2 to 7.2, P=0.008). Conclusions Among young adults, an increase in leisure-time physical activity or staying active during a decade of follow-up was associated with less waist gain, but any decrease in activity level, regardless baseline activity, led to waist gain that was similar to that associated with being persistently inactive. PMID:24839266

Overview of Materials International Space Station Experiment 7B

NASA Technical Reports Server (NTRS)

Jaworske, Donald A.; Siamidis, John

2009-01-01

Materials International Space Station Experiment 7B (MISSE 7B) is the most recent in a series of experiments flown on the exterior of International Space Station for the purpose of determining the durability of materials and components in the space environment. A collaborative effort among the Department of Defense, the National Aeronautics and Space Administration, industry, and academia, MISSE 7B will be flying a number of NASA experiments designed to gain knowledge in the area of space environmental effects to mitigate risk for exploration missions. Consisting of trays called Passive Experiment Containers, the suitcase sized payload opens on hinges and allows active and passive experiments contained within to be exposed to the ram and wake or zenith and nadir directions in low Earth orbit, in essence, providing a test bed for atomic oxygen exposure, ultraviolet radiation exposure, charged particle radiation exposure, and thermal cycling. New for MISSE 7B is the ability to monitor experiments actively, with data sent back to Earth via International Space Station communications. NASA?s active and passive experiments cover a range of interest for the Agency. Materials relevant to the Constellation Program include: solar array materials, seal materials, and thermal protection system materials. Materials relevant to the Exploration Technology Development Program include: fabrics for spacesuits, materials for lunar dust mitigation, and new thermal control coatings. Sensors and components on MISSE 7B include: atomic oxygen fluence monitors, ultraviolet radiation sensors, and electro-optical components. In addition, fundamental space environmental durability science experiments are being flown to gather atomic oxygen erosion data and thin film polymer mechanical and optical property data relevant to lunar lander insulation and the James Web Space Telescope. This paper will present an overview of the NASA experiments to be flown on MISSE 7B, along with a summary of the thermal environment to be expected during the 1 yr mission scheduled for launch in 2009.

Application of Yb:YAG short pulse laser system

DOEpatents

Erbert, Gaylen V.; Biswal, Subrat; Bartolick, Joseph M.; Stuart, Brent C.; Crane, John K.; Telford, Steve; Perry, Michael D.

2004-07-06

A diode pumped, high power (at least 20W), short pulse (up to 2 ps), chirped pulse amplified laser using Yb:YAG as the gain material is employed for material processing. Yb:YAG is used as the gain medium for both a regenerative amplifier and a high power 4-pass amplifier. A single common reflective grating optical device is used to both stretch pulses for amplification purposes and to recompress amplified pulses before being directed to a workpiece.

The Theory, Development, and Implementation of an e-Intervention to Prevent Excessive Gestational Weight Gain: e-Moms Roc

PubMed Central

Uesugi, Keriann H.; Niederdeppe, Jeff; Gay, Geri K.; Olson, Christine M.

2014-01-01

Abstract Background: Gaining more weight during pregnancy than is recommended by the Institute of Medicine is prevalent and contributes to the development of obesity in women. This article describes the development and use of e-Moms of Rochester (e-Moms Roc), an electronic intervention (e-intervention), to address this health issue in a socioeconomically diverse sample of pregnant women. Materials and Methods: Formative research in the form of intercept interviews, in-depth interviews, and focus groups was conducted to inform the design of the e-intervention. The Web site continuously tracked each participant's use of e-intervention features. Results: An e-intervention, including Web site and mobile phone components, was developed and implemented in a randomized control trial. Formative research informed the design. Participants in all arms accessed blogs, local resources, articles, frequently asked questions, and events. Participants in the intervention arms also accessed the weight gain tracker and diet and physical activity goal-setting tools. Overall, 80% of women logged into the Web site and used a tool or feature at least twice. Among those in the intervention arm, 70% used the weight gain tracker, but only 40% used the diet and physical activity goal-setting tools. Conclusions: To maximize and sustain potential usage of e-Moms Roc over time, the e-intervention included customized reminders, tailored content, and community features such as blogs and resources. Usage was comparable to those in other weight studies with young adults and higher than reported in a published study with pregnant women. This e-intervention specifically designed for pregnant women was used by the majority of women. PMID:25354350

Li(x)FeF6 (x = 2, 3, 4) battery materials: structural, electronic and lithium diffusion properties.

PubMed

Schroeder, Melanie; Eames, Christopher; Tompsett, David A; Lieser, Georg; Islam, M Saiful

2013-12-21

Lithium iron fluoride materials have attracted recent interest as cathode materials for lithium ion batteries. The electrochemical properties of the high energy density Li(x)FeF6 (x = 2, 3, 4) materials have been evaluated using a combination of potential-based and DFT computational methods. Voltages of 6.1 V and 3.0 V are found for lithium intercalation from Li2FeF6 to α-Li3FeF6 and α-Li3FeF6 to Li4FeF6 respectively. The calculated density of states indicate that Li2FeF6 possesses metallic states that become strongly insulating after lithium intercalation to form α-Li3FeF6. The large energy gain associated with this metal-insulator transition is likely to contribute to the associated large voltage of 6.1 V. Molecular dynamics simulations of lithium diffusion in α-Li3FeF6 at typical battery operating temperatures indicate high lithium-ion mobility with low activation barriers. These results suggest the potential for good rate performance of lithium iron fluoride cathode materials.

Effects of physical activity during pregnancy and gestational weight gain on newborn weight and length at birth in Warmińsko-Mazurskie province.

PubMed

Przybyłowicz, Katarzyna; Przybyłowicz, Mariusz; Grzybiak, Marek; Janiszewska, Katarzyna

2014-01-01

Epidemiological research has identified a relationship between maternal physical activity, early nutrition and infant birth weight with likelihood of developing future diseases. The aim of the study was to determine a relationship between gestational weight gain and physical activity during pregnancy to the nutritional status of newborns. The presented study was conducted in the period from February 2010 until November 2012 in the gynecological and obstetric clinics in Warmińsko-Mazurskie voivodeship with various levels of reference. The research subjects included 510 women in the puerperal period aged 18-36. The scope of the research included an assessment of the selected anthropometric parameters of both pregnant women (body mass, height, BMI, gestational weight gain) and newborns (infant birth weight, infant length, Ponderal Index), as well as an analysis of the connections between the gestational weight gain, physical activity during pregnancy and anthropometric parameters of newborns. In the study group there was a significant percentage of women characterised by an inactive lifestyle and excessive gestational weight gain. There were significantly higher neonatal birth anthropometric parameters in women with abnormal excessive gestational weight gain than in women with normal and inappropriate - low gestational weight gain. The highest percentage of women with appropriate weight gain was observed in the group of women who are physically active, although this requires confirmation in larger population. Our studies have not shown statistically significant differences between the gestational weight gain and nutritional status of newborns in relation to the level of physical activity of pregnant women.

Locating Sensors for Detecting Source-to-Target Patterns of Special Nuclear Material Smuggling: A Spatial Information Theoretic Approach

PubMed Central

Przybyla, Jay; Taylor, Jeffrey; Zhou, Xuesong

2010-01-01

In this paper, a spatial information-theoretic model is proposed to locate sensors for detecting source-to-target patterns of special nuclear material (SNM) smuggling. In order to ship the nuclear materials from a source location with SNM production to a target city, the smugglers must employ global and domestic logistics systems. This paper focuses on locating a limited set of fixed and mobile radiation sensors in a transportation network, with the intent to maximize the expected information gain and minimize the estimation error for the subsequent nuclear material detection stage. A Kalman filtering-based framework is adapted to assist the decision-maker in quantifying the network-wide information gain and SNM flow estimation accuracy. PMID:22163641

Locating sensors for detecting source-to-target patterns of special nuclear material smuggling: a spatial information theoretic approach.

PubMed

Przybyla, Jay; Taylor, Jeffrey; Zhou, Xuesong

2010-01-01

In this paper, a spatial information-theoretic model is proposed to locate sensors for detecting source-to-target patterns of special nuclear material (SNM) smuggling. In order to ship the nuclear materials from a source location with SNM production to a target city, the smugglers must employ global and domestic logistics systems. This paper focuses on locating a limited set of fixed and mobile radiation sensors in a transportation network, with the intent to maximize the expected information gain and minimize the estimation error for the subsequent nuclear material detection stage. A Kalman filtering-based framework is adapted to assist the decision-maker in quantifying the network-wide information gain and SNM flow estimation accuracy.

Design of hybrid laser structures with QD-RSOA and silicon photonic mirrors

NASA Astrophysics Data System (ADS)

Gioannini, Mariangela; Benedetti, Alessio; Bardella, Paolo; Bovington, Jock; Traverso, Matt; Siriani, Dominic; Gothoskar, Prakash

2018-02-01

We compare the design of three different single mode laser structures consisting in a Reflective Semiconductor Optical Amplifier coupled to a silicon photonic external cavity mirror. The three designs differ for the mirror structure and are compared in terms of SOA power consumption and side mode suppression ratio (SMSR). Assuming then a Quantum Dot active material, we simulate the best laser design using a numerical model that includes the peculiar physical characteristics of the QD gain medium. The simulated QD laser CW characteristics are shown and discussed.

Engine/airframe compatibility studies for supersonic cruise aircraft

NASA Technical Reports Server (NTRS)

1975-01-01

Technology assessment studies were conducted to provide an updated technology base from which an advanced supersonic cruise aircraft can be produced with a high probability of success. An assessment of the gains available through the application of advanced technologies in aerodynamics, propulsion, acoustics, structures, materials, and active controls is developed. The potential market and range requirements as well as economic factors including payload, speed, airline operating costs, and airline profitability are analyzed. The conceptual design of the baseline aircraft to be used in assessing the technology requirements is described.

Combined effects of nonparaxiality, optical activity, and walk-off on rogue wave propagation in optical fibers filled with chiral materials.

PubMed

Temgoua, D D Estelle; Tchokonte, M B Tchoula; Kofane, T C

2018-04-01

The generalized nonparaxial nonlinear Schrödinger (NLS) equation in optical fibers filled with chiral materials is reduced to the higher-order integrable Hirota equation. Based on the modified Darboux transformation method, the nonparaxial chiral optical rogue waves are constructed from the scalar model with modulated coefficients. We show that the parameters of nonparaxiality, third-order dispersion, and differential gain or loss term are the main keys to control the amplitude, linear, and nonlinear effects in the model. Moreover, the influence of nonparaxiality, optical activity, and walk-off effect are also evidenced under the defocusing and focusing regimes of the vector nonparaxial NLS equations with constant and modulated coefficients. Through an algorithm scheme of wider applicability on nonparaxial beam propagation methods, the most influential effect and the simultaneous controllability of combined effects are underlined, showing their properties and their potential applications in optical fibers and in a variety of complex dynamical systems.

Combined effects of nonparaxiality, optical activity, and walk-off on rogue wave propagation in optical fibers filled with chiral materials

NASA Astrophysics Data System (ADS)

Temgoua, D. D. Estelle; Tchokonte, M. B. Tchoula; Kofane, T. C.

2018-04-01

The generalized nonparaxial nonlinear Schrödinger (NLS) equation in optical fibers filled with chiral materials is reduced to the higher-order integrable Hirota equation. Based on the modified Darboux transformation method, the nonparaxial chiral optical rogue waves are constructed from the scalar model with modulated coefficients. We show that the parameters of nonparaxiality, third-order dispersion, and differential gain or loss term are the main keys to control the amplitude, linear, and nonlinear effects in the model. Moreover, the influence of nonparaxiality, optical activity, and walk-off effect are also evidenced under the defocusing and focusing regimes of the vector nonparaxial NLS equations with constant and modulated coefficients. Through an algorithm scheme of wider applicability on nonparaxial beam propagation methods, the most influential effect and the simultaneous controllability of combined effects are underlined, showing their properties and their potential applications in optical fibers and in a variety of complex dynamical systems.

Low threshold Amplified Spontaneous Emission properties in deep blue of poly[(9,9-dioctylfluorene-2,7-dyil)-alt-p-phenylene] thin films

NASA Astrophysics Data System (ADS)

Lattante, Sandro; De Giorgi, Maria Luisa; Pasini, Mariacecilia; Anni, Marco

2017-10-01

Amongst the different optoelectronic applications of conjugated polymers, the development of new active materials for optically pumped organic lasers is still an open question particularly in the blue-near UV spectral range. We investigate the emission properties of poly[(9,9-dioctylfluorene-2,7-dyil)- alt-p-phenylene] (PFP) neat films under nanosecond pump. We demonstrate that thanks to the introduction of a phenylene moiety between two fluorene units it is possible to obtain Amplified Spontaneous Emission (ASE) with a lower threshold and a blue shifted wavelength with respect to poly(9,9-dioctylfluorene) (PFO). We demonstrate efficient ASE with a minimum threshold as low as 23 μJcm-2 and a minimum ASE wavelength of 436 nm. A maximum net optical gain of about 26 cm-1 is measured at an excitation density of 0.23 mJcm-2. These results make the PFP a good active material for optically pumped deep blue organic lasers.

Cobalt and sulfur co-doped nano-size TiO2 for photodegradation of various dyes and phenol.

PubMed

Siddiqa, Asima; Masih, Dilshad; Anjum, Dalaver; Siddiq, Muhammad

2015-11-01

Various compositions of cobalt and sulfur co-doped titania nano-photocatalyst are synthesized via sol-gel method. A number of techniques including X-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Rutherford backscattering spectrometry (RBS), thermal gravimetric analysis (TGA), Raman, N2 sorption, electron microscopy are used to examine composition, crystalline phase, morphology, distribution of dopants, surface area and optical properties of synthesized materials. The synthesized materials consisted of quasispherical nanoparticles of anatase phase exhibiting a high surface area and homogeneous distribution of dopants. Cobalt and sulfur co-doped titania demonstrated remarkable structural and optical properties leading to an efficient photocatalytic activity for degradation of dyes and phenol under visible light irradiations. Moreover, the effect of dye concentration, catalyst dose and pH on photodegradation behavior of environmental pollutants and recyclability of the catalyst is also examined to optimize the activity of nano-photocatalyst and gain a better understanding of the process. Copyright © 2015. Published by Elsevier B.V.

(Bio)hybrid materials based on optically active particles

NASA Astrophysics Data System (ADS)

Reitzig, Manuela; Härtling, Thomas; Opitz, Jörg

2014-03-01

In this contribution we provide an overview of current investigations on optically active particles (nanodiamonds, upconversion phospors) for biohybrid and sensing applications. Due to their outstanding properties nanodiamonds gain attention in various application elds such as microelectronics, optical monitoring, medicine, and biotechnology. Beyond the typical diamond properties such as high thermal conductivity and extreme hardness, the carbon surface and its various functional groups enable diverse chemical and biological surface functionalization. At Fraunhofer IKTS-MD we develop a customization of material surfaces via integration of chemically modi ed nanodiamonds at variable surfaces, e.g bone implants and pipelines. For the rst purpose, nanodiamonds are covalently modi ed at their surface with amino or phosphate functionalities that are known to increase adhesion to bone or titanium alloys. The second type of surface is approached via mechanical implementation into coatings. Besides nanodiamonds, we also investigate the properties of upconversion phosphors. In our contribution we show how upconversion phosphors are used to verify sterilization processes via a change of optical properties due to sterilizing electron beam exposure.

Evaluation of waste concrete road materials for use in oyster aquaculture - phase 3 : research summary.

DOT National Transportation Integrated Search

2016-08-01

The use of recycled materials has gained increased attention for the environmental benefits, and the reuse of industrial by-products and waste materials can provide a stream of revenue for producers and a durable, cost-effective material option for e...

Method to predict relative hydriding within a group of zirconium alloys under nuclear irradiation

DOEpatents

Johnson, Jr., A. Burtron; Levy, Ira S.; Trimble, Dennis J.; Lanning, Donald D.; Gerber, Franna S.

1990-01-01

An out-of-reactor method for screening to predict relative in-reactor hydriding behavior of zirconium-bsed materials is disclosed. Samples of zirconium-based materials having different composition and/or fabrication are autoclaved in a relatively concentrated (0.3 to 1.0M) aqueous lithium hydroxide solution at constant temperatures within the water reactor coolant temperature range (280.degree. to 316.degree. C.). Samples tested by this out-of-reactor procedure, when compared on the basis of the ratio of hydrogen weight gain to oxide weight gain, accurately predict the relative rate of hyriding for the same materials when subject to in-reactor (irradiated) corrision.

Development and characterization of silica and titania based nano structured materials for the removal of indoor and outdoor air pollutants

NASA Astrophysics Data System (ADS)

Peiris, Thelge Manindu Nirasha

Solar energy driven catalytic systems have gained popularity in environmental remediation recently. Various photocatalytic systems have been reported in this regard and most of the photocatalysts are based on well-known semiconducting material, Titanium Dioxide, while some are based on other materials such as Silicon Dioxide and various Zeolites. However, in titania based photocatalysts, titania is actively involved in the catalytic mechanism by absorbing light and generating exitons. Because of this vast popularity of titania in the field of photocatalysis it is believed that photocatalysis mainly occurs via non-localized mechanisms and semiconductors are extremely important. Even though it is still rare, photocatalysis could be localized and possible without use of a semiconductor as well. Thus, to support localized photocatalytic systems, and to compare the activity to titania based systems, degradation of organic air pollutants by nanostructured silica, titania and mixed silica titania systems were studied. New materials were prepared using two different approaches, precipitation technique (xerogel) and aerogel preparation technique. The prepared xerogel samples were doped with both metal (silver) and non-metals (carbon and sulfur) and aerogel samples were loaded with Chromium, Cobalt and Vanadium separately, in order to achieve visible light photocatalytic activity. Characterization studies of the materials were carried out using Nova BET analysis, DR UV-vis spectrometry, powder X-ray diffraction, X-ray photoelectron Spectroscopy, FT-IR spectroscopy, Transmission Electron Microscopy, etc. Kinetics of the catalytic activities was studied using a Shimadzu GCMS-QP 5000 instrument using a closed glass reactor. All the experiments were carried out in gaseous phase using acetaldehyde as the model pollutant. Kinetic results suggest that chromium doped silica systems are good UV and visible light active photocatalysts. This is a good example for a localized photocatalytic activity. In contrast, our xerogel system shows comparatively high visible light photocatalytic activity for the titania based system, showing the importance of non-localized nature of photocatalysis. The Cobalt doped silica system shows interesting dark catalytic activity towards acetaldehyde and several other pollutants. Thus, in summary, based on the different activities we observed during our studies these materials could be successfully used to improve the quality of both indoor and outdoor air.

Occurrence and distribution of selected metals in streams near Huntsville, Alabama

USGS Publications Warehouse

German, E.R.; Knight, Alfred L.

1973-01-01

Arsenic, cadmium, chromium, cobalt, lead, mercury, and zinc are widely distributed around Huntsville, Ala. However, concentrations of these metals in streamflow in the vicinity of the Huntsville municipal water intake during June, August, and September 1971 did not exceed the limits recommended for a public drinking water supply. The occurrence of these metals in general is related to man's activities. Information gained during this study suggests that cadmium and the other metals are associated with and transported with suspended sediment, bed material, and airborne dust particles. Lead and zinc were the most abundant of the selected metals in streamflow, bed material, and rainwater samples. The highest concentration of cadmium was detected downstream from an industrial park in the Flint River basin; rainwater samples also contained a relatively high level of cadmium.

Pulse-shape discrimination scintillators for homeland security applications

NASA Astrophysics Data System (ADS)

Ellis, Mark E.; Duroe, Kirk; Kendall, Paul A.

2016-09-01

An extensive programme of research has been conducted for scintillation liquids and plastics capable of neutron-gamma discrimination for deployment in future passive and active Homeland Security systems to provide protection against radiological and nuclear threats. The more established detection materials such as EJ-301 and EJ-309 are compared with novel materials such as EJ-299-33 and p-terphenyl. This research also explores the benefits that can be gained from improvements in the analogue-to-digital sampling rate and sample bit resolution. Results are presented on the Pulse Shape Discrimination performance of various detector and data acquisition combinations and how optimum configurations from these studies have been developed into field-ready detector arrays. Early results from application-specific experimental configurations of multi-element detector arrays are presented.

Extension materials for meat-borne parasitic diseases in developing countries.

PubMed

Rimm, Mogens

2003-06-01

In support of a project on porcine cysticercosis in Tanzania, an educational video was prepared to inform the rural communities on the health risks and prevention of the parasitic disease. This paper describes the process involved in making the video, especially the importance of establishing a good understanding between veterinary public health officials and the video producer. Important steps in the process include determining the target audience, the film's core message, the construction of the "story", script development, the filming and editing activities, and, importantly, the development of strategies for production and use of the film as extension material. Suggestions on logistical and technical aspects of filming and viewing are also discussed. The experience gained in Tanzania will be of value to others planning similar projects elsewhere.

A compact Nd:YAG DPSSL using diamond-cooled technology

NASA Astrophysics Data System (ADS)

Chou, Hsian P.; Wang, Yu-Lin; Hasson, Victor H.; Trainor, Daniel W.

2005-03-01

In our diamond-cooled approach, thin disks of laser gain material, e.g., Nd:YAG, are alternated between thin disks of single crystal synthetic diamond whose heat conductivity is over 2000 W/m-°K. The gain medium is face-pumped (along the optical axis) by the output of laser diode arrays. This optical configuration produces heat transfer from Nd:YAG to the diamond, in the direction of the optical axis, and then heat is rapidly conducted radially outward through the diamond to the cooling fluid circulating at the circumference of the diamond/YAG assembly. This geometry effectively removes the heat from the gain material in a manner that permits the attainment of high power output with excellent beam quality.

Studying Radiation Damage in Structural Materials by Using Ion Accelerators

NASA Astrophysics Data System (ADS)

Hosemann, Peter

2011-02-01

Radiation damage in structural materials is of major concern and a limiting factor for a wide range of engineering and scientific applications, including nuclear power production, medical applications, or components for scientific radiation sources. The usefulness of these applications is largely limited by the damage a material can sustain in the extreme environments of radiation, temperature, stress, and fatigue, over long periods of time. Although a wide range of materials has been extensively studied in nuclear reactors and neutron spallation sources since the beginning of the nuclear age, ion beam irradiations using particle accelerators are a more cost-effective alternative to study radiation damage in materials in a rather short period of time, allowing researchers to gain fundamental insights into the damage processes and to estimate the property changes due to irradiation. However, the comparison of results gained from ion beam irradiation, large-scale neutron irradiation, and a variety of experimental setups is not straightforward, and several effects have to be taken into account. It is the intention of this article to introduce the reader to the basic phenomena taking place and to point out the differences between classic reactor irradiations and ion irradiations. It will also provide an assessment of how accelerator-based ion beam irradiation is used today to gain insight into the damage in structural materials for large-scale engineering applications.

Early differential processing of material images: Evidence from ERP classification.

PubMed

Wiebel, Christiane B; Valsecchi, Matteo; Gegenfurtner, Karl R

2014-06-24

Investigating the temporal dynamics of natural image processing using event-related potentials (ERPs) has a long tradition in object recognition research. In a classical Go-NoGo task two characteristic effects have been emphasized: an early task independent category effect and a later task-dependent target effect. Here, we set out to use this well-established Go-NoGo paradigm to study the time course of material categorization. Material perception has gained more and more interest over the years as its importance in natural viewing conditions has been ignored for a long time. In addition to analyzing standard ERPs, we conducted a single trial ERP pattern analysis. To validate this procedure, we also measured ERPs in two object categories (people and animals). Our linear classification procedure was able to largely capture the overall pattern of results from the canonical analysis of the ERPs and even extend it. We replicate the known target effect (differential Go-NoGo potential at frontal sites) for the material images. Furthermore, we observe task-independent differential activity between the two material categories as early as 140 ms after stimulus onset. Using our linear classification approach, we show that material categories can be differentiated consistently based on the ERP pattern in single trials around 100 ms after stimulus onset, independent of the target-related status. This strengthens the idea of early differential visual processing of material categories independent of the task, probably due to differences in low-level image properties and suggests pattern classification of ERP topographies as a strong instrument for investigating electrophysiological brain activity. © 2014 ARVO.

Root-cause estimation of ultrasonic scattering signatures within a complex textured titanium

NASA Astrophysics Data System (ADS)

Blackshire, James L.; Na, Jeong K.; Freed, Shaun

2016-02-01

The nondestructive evaluation of polycrystalline materials has been an active area of research for many decades, and continues to be an area of growth in recent years. Titanium alloys in particular have become a critical material system used in modern turbine engine applications, where an evaluation of the local microstructure properties of engine disk/blade components is desired for performance and remaining life assessments. Current NDE methods are often limited to estimating ensemble material properties or detecting localized voids, inclusions, or damage features within a material. Recent advances in computational NDE and material science characterization methods are providing new and unprecedented access to heterogeneous material properties, which permits microstructure-sensing interactions to be studied in detail. In the present research, Integrated Computational Materials Engineering (ICME) methods and tools are being leveraged to gain a comprehensive understanding of root-cause ultrasonic scattering processes occurring within a textured titanium aerospace material. A combination of destructive, nondestructive, and computational methods are combined within the ICME framework to collect, holistically integrate, and study complex ultrasound scattering using realistic 2-dimensional representations of the microstructure properties. Progress towards validating the computational sensing methods are discussed, along with insight into the key scattering processes occurring within the bulk microstructure, and how they manifest in pulse-echo immersion ultrasound measurements.

Gain determination of optical active doped planar waveguides

NASA Astrophysics Data System (ADS)

Šmejcký, J.; Jeřábek, V.; Nekvindová, P.

2017-12-01

This paper summarizes the results of the gain transmission characteristics measurement carried out on the new ion exchange Ag+ - Na+ optical Er3+ and Yb3+ doped active planar waveguides realized on a silica based glass substrates. The results were used for optimization of the precursor concentration in the glass substrates. The gain measurements were performed by the time domain method using a pulse generator, as well as broadband measurement method using supercontinuum optical source in the wavelength domain. Both methods were compared and the results were graphically processed. It has been confirmed that pulse method is useful as it provides a very accurate measurement of the gain - pumping power characteristics for one wavelength. In the case of radiation spectral characteristics, our measurement exactly determined the maximum gain wavelength bandwidth of the active waveguide. The spectral characteristics of the pumped and unpumped waveguides were compared. The gain parameters of the reported silica-based glasses can be compared with the phosphate-based parameters, typically used for optical active devices application.

Leisure Time Physical Activity of Moderate to Vigorous Intensity and Mortality: A Large Pooled Cohort Analysis

PubMed Central

Moore, Steven C.; Patel, Alpa V.; Matthews, Charles E.; Berrington de Gonzalez, Amy; Park, Yikyung; Katki, Hormuzd A.; Linet, Martha S.; Weiderpass, Elisabete; Visvanathan, Kala; Helzlsouer, Kathy J.; Thun, Michael; Gapstur, Susan M.; Hartge, Patricia; Lee, I-Min

2012-01-01

Background Leisure time physical activity reduces the risk of premature mortality, but the years of life expectancy gained at different levels remains unclear. Our objective was to determine the years of life gained after age 40 associated with various levels of physical activity, both overall and according to body mass index (BMI) groups, in a large pooled analysis. Methods and Findings We examined the association of leisure time physical activity with mortality during follow-up in pooled data from six prospective cohort studies in the National Cancer Institute Cohort Consortium, comprising 654,827 individuals, 21–90 y of age. Physical activity was categorized by metabolic equivalent hours per week (MET-h/wk). Life expectancies and years of life gained/lost were calculated using direct adjusted survival curves (for participants 40+ years of age), with 95% confidence intervals (CIs) derived by bootstrap. The study includes a median 10 y of follow-up and 82,465 deaths. A physical activity level of 0.1–3.74 MET-h/wk, equivalent to brisk walking for up to 75 min/wk, was associated with a gain of 1.8 (95% CI: 1.6–2.0) y in life expectancy relative to no leisure time activity (0 MET-h/wk). Higher levels of physical activity were associated with greater gains in life expectancy, with a gain of 4.5 (95% CI: 4.3–4.7) y at the highest level (22.5+ MET-h/wk, equivalent to brisk walking for 450+ min/wk). Substantial gains were also observed in each BMI group. In joint analyses, being active (7.5+ MET-h/wk) and normal weight (BMI 18.5–24.9) was associated with a gain of 7.2 (95% CI: 6.5–7.9) y of life compared to being inactive (0 MET-h/wk) and obese (BMI 35.0+). A limitation was that physical activity and BMI were ascertained by self report. Conclusions More leisure time physical activity was associated with longer life expectancy across a range of activity levels and BMI groups. Please see later in the article for the Editors' Summary PMID:23139642

Project LITE - Light Inquiry Through Experiments

NASA Astrophysics Data System (ADS)

Brecher, K.

2004-12-01

Hands-on, inquiry-based, constructivist activity offers students a powerful way to explore, uncover and ultimately gain a feel for the nature of science. In order to make practicable a more genuine approach to learning astronomy, we have undertaken the development of hands-on (and eyes-on) materials that can be used in introductory undergraduate astronomy courses. These materials focus on light and optics. Over the past several years as part of Project LITE (Light Inquiry Through Experiments), we have developed a kit of optical materials that is integrated with a set of Java applets. The combined kit and software allows students to do actual experiments concerning geometrical optics, fluorescence, phosphorescence, polarization and other topics by making use of the photons that are emitted by their computer screens. We have also developed a suite of over 100 Flash applets that allow students to directly explore many aspects of visual perception. A major effort of the project concerns spectroscopy, since it is arguably the most important tool used by astronomers to disentangle the nature of the universe. It is also one of the most challenging subjects to teach in undergraduate astronomy courses. The spectroscopy component of Project LITE includes take-home laboratory materials and experiments that are integrated with web-based software. We have also developed a novel quantitative handheld binocular spectrometer (patent pending). Our major spectroscopic software is called the Spectrum Explorer (SPEX). It allows students to create, manipulate and explore all types of spectra including blackbody, power law, emission and absorption. We are now extending the SPEX capabilities to help students gain easy access to the astronomical spectra included in the NVO databases. All of the Project LITE software can be found http://lite.bu.edu. Project LITE is supported by Grant #DUE-0125992 from the NSF Division of Undergraduate Education.

A Randomized Crossover Design to Assess Learning Impact and Student Preference for Active and Passive Online Learning Modules.

PubMed

Prunuske, Amy J; Henn, Lisa; Brearley, Ann M; Prunuske, Jacob

Medical education increasingly involves online learning experiences to facilitate the standardization of curriculum across time and space. In class, delivering material by lecture is less effective at promoting student learning than engaging students in active learning experience and it is unclear whether this difference also exists online. We sought to evaluate medical student preferences for online lecture or online active learning formats and the impact of format on short- and long-term learning gains. Students participated online in either lecture or constructivist learning activities in a first year neurologic sciences course at a US medical school. In 2012, students selected which format to complete and in 2013, students were randomly assigned in a crossover fashion to the modules. In the first iteration, students strongly preferred the lecture modules and valued being told "what they need to know" rather than figuring it out independently. In the crossover iteration, learning gains and knowledge retention were found to be equivalent regardless of format, and students uniformly demonstrated a strong preference for the lecture format, which also on average took less time to complete. When given a choice for online modules, students prefer passive lecture rather than completing constructivist activities, and in the time-limited environment of medical school, this choice results in similar performance on multiple-choice examinations with less time invested. Instructors need to look more carefully at whether assessments and learning strategies are helping students to obtain self-directed learning skills and to consider strategies to help students learn to value active learning in an online environment.

An extension of incidental teaching procedures to reading instruction for autistic children.

PubMed Central

McGee, G G; Krantz, P J; McClannahan, L E

1986-01-01

In an extension of incidental teaching procedures to reading instruction, two autistic children acquired functional sight-word reading skills in the context of a play activity. Children gained access to preferred toys by selecting the label of the toy in tasks requiring increasingly complex visual discriminations. In addition to demonstrating rapid acquisition of 5-choice discriminations, they showed comprehension on probes requiring reading skills to locate toys stored in labeled boxes. Also examined was postteaching transfer across stimulus materials and response modalities. Implications are that extensions of incidental teaching to new response classes may produce the same benefits documented in communication training, in terms of producing generalization concurrent with skill acquisition in the course of child-preferred activities. PMID:3733586

Cultural-historical activity theory: Vygotsky's forgotten and suppressed legacy and its implication for mathematics education

NASA Astrophysics Data System (ADS)

Roth, Wolff-Michael

2012-03-01

Cultural-historical activity theory—with historical roots in dialectical materialism and the social psychology to which it has given rise—has experienced exponential growth in its acceptance by scholars interested in understanding knowing and learning writ large. In education, this theory has constituted something like a well kept secret that is only in the process of gaining larger levels of acceptance. Mathematics educators are only beginning to realise the tremendous advantages that the theory provides over other theories. In this review essay, I articulate the theory as it may relate to the issues that concern mathematics education and educators with a particular focus on the way in which it addresses logical contradictions in existing theories.

Qualitative Assessment of Key Messages about Nutrition and Weight Gain in Pregnancy in Printed Educational Materials in Alberta.

PubMed

Forbes, Laura; Baarda, Janis; Mayan, Maria; Bell, Rhonda C

2017-12-01

Printed educational materials are a common source of health information, although their effectiveness in improving women's knowledge or self-care in pregnancy has been questioned. This study describes the information in printed educational materials that address healthy eating during pregnancy and gestational weight gain (GWG) that are currently used in Alberta, Canada. Content of 6 resources was analyzed using a constant comparison qualitative approach. Resources emphasized healthy eating, prenatal supplements, folate supplementation, and healthy weight gain. More resources discussed the importance of "eating enough" than provided guidance on avoiding excessive GWG. Themes identified were: "everything is important" meaning that all healthy behaviours are important, making prioritization difficult; "more is more" emphasized eating more over moderation; "everyone is individual" suggests women seek individualized care through the care provider; and "contradictions" describes differences in content and recommendations within and between resources. New or revised versions of resources should provide congruent information with up-to-date recommendations that are easily prioritized. Care providers should be aware of contradictory information or information that does not align with current recommendations within printed educational materials and be ready to help women address the areas important for her personal behaviour change.

Method to predict relative hydriding within a group of zirconium alloys under nuclear irradiation

DOEpatents

Johnson, A.B. Jr.; Levy, I.S.; Trimble, D.J.; Lanning, D.D.; Gerber, F.S.

1990-04-10

An out-of-reactor method for screening to predict relative in-reactor hydriding behavior of zirconium-based materials is disclosed. Samples of zirconium-based materials having different compositions and/or fabrication methods are autoclaved in a relatively concentrated (0.3 to 1.0M) aqueous lithium hydroxide solution at constant temperatures within the water reactor coolant temperature range (280 to 316 C). Samples tested by this out-of-reactor procedure, when compared on the basis of the ratio of hydrogen weight gain to oxide weight gain, accurately predict the relative rate of hydriding for the same materials when subject to in-reactor (irradiated) corrosion. 1 figure.

20 CFR 416.971 - General.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Determining Disability and Blindness Substantial Gainful Activity § 416.971 General. The work, without regard... you are able to work at the substantial gainful activity level. If you are able to engage in... are statutorily blind in § 416.984.) Even if the work you have done was not substantial gainful...

20 CFR 416.971 - General.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Determining Disability and Blindness Substantial Gainful Activity § 416.971 General. The work, without regard... you are able to work at the substantial gainful activity level. If you are able to engage in... are statutorily blind in § 416.984.) Even if the work you have done was not substantial gainful...

20 CFR 404.1571 - General.

Code of Federal Regulations, 2013 CFR

2013-04-01

...- ) Determining Disability and Blindness Substantial Gainful Activity § 404.1571 General. The work, without regard... you are able to work at the substantial gainful activity level. If you are able to engage in... are statutorily blind in § 404.1584.) Even if the work you have done was not substantial gainful...

20 CFR 416.971 - General.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Determining Disability and Blindness Substantial Gainful Activity § 416.971 General. The work, without regard... you are able to work at the substantial gainful activity level. If you are able to engage in... are statutorily blind in § 416.984.) Even if the work you have done was not substantial gainful...

20 CFR 404.1571 - General.

Code of Federal Regulations, 2012 CFR

2012-04-01

...- ) Determining Disability and Blindness Substantial Gainful Activity § 404.1571 General. The work, without regard... you are able to work at the substantial gainful activity level. If you are able to engage in... are statutorily blind in § 404.1584.) Even if the work you have done was not substantial gainful...

20 CFR 404.1571 - General.

Code of Federal Regulations, 2014 CFR

2014-04-01

...- ) Determining Disability and Blindness Substantial Gainful Activity § 404.1571 General. The work, without regard... you are able to work at the substantial gainful activity level. If you are able to engage in... are statutorily blind in § 404.1584.) Even if the work you have done was not substantial gainful...

Simulations on false gain in recombination-pumped soft-X-ray lasers

NASA Astrophysics Data System (ADS)

Ozaki, T.; Kuroda, H.

1997-10-01

Numerical investigations are performed on false gain due to axial plasma expansion, which is expected to be important in initial proof-of-principle studies of recombination-pumped soft-X-ray lasers with extended capabilities. Modelling calculations of experiments with slab boron nitride targets reveal large false gain coefficients approaching 20 cm-1 in the case of plasmas with short active medium lengths. The false gain in the case of fiber targets is found to be of equal magnitude to that for slabs in the case of plasmas with less than 0.1 cm active medium lengths. Calculations for slab targets predict that adopting a tolerance of ǃ cm-1 for gain will severely restrict the time and the active medium length of the plasma that can be used for error-free observations, while those for fiber targets are found to be considerably relaxed. The effects of false gain in the 54.2 + Na Balmer ! laser is also investigated, again revealing the importance of this phenomena under optimum gain conditions.

The impact of loading approach and biological activity on NOM removal by ion exchange resins.

PubMed

Winter, Joerg; Wray, Heather E; Schulz, Martin; Vortisch, Roman; Barbeau, Benoit; Bérubé, Pierre R

2018-05-01

The present study investigated the impact of different loading approaches and microbial activity on the Natural Organic Matter (NOM) removal efficiency and capacity of ion exchange resins. Gaining further knowledge on the impact of loading approaches is of relevance because laboratory-scale multiple loading tests (MLTs) have been introduced as a simpler and faster alternative to column tests for predicting the performance of IEX, but only anecdotal evidence exists to support their ability to forecast contaminant removal and runtime until breakthrough of IEX systems. The overall trends observed for the removal and the time to breakthrough of organic material estimated using MLTs differed from those estimated using column tests. The results nonetheless suggest that MLTs could best be used as an effective tool to screen different ion exchange resins in terms of their ability to remove various contaminants of interest from different raw waters. The microbial activity was also observed to impact the removal and time to breakthrough. In the absence of regeneration, a microbial community rapidly established itself in ion exchange columns and contributed to the removal of organic material. Biological ion exchange (BIEX) removed more organic material and enabled operation beyond the point when the resin capacity would have otherwise been exhausted using conventional (i.e. in the absence of a microbial community) ion exchange. Furthermore, significantly greater removal of organic matter could be achieved with BIEX than biological activated carbon (BAC) (i.e. 56 ± 7% vs. 15 ± 5%, respectively) when operated at similar loading rates. The results suggest that for some raw waters, BIEX could replace BAC as the technology of choice for the removal of organic material. Copyright © 2018 Elsevier Ltd. All rights reserved.

The association of birth weight and infant growth with childhood autonomic nervous system activity and its mediating effects on energy-balance-related behaviours-the ABCD study.

PubMed

van Deutekom, Arend W; Chinapaw, Mai Jm; Gademan, Maaike Gj; Twisk, Jos Wr; Gemke, Reinoud Jbj; Vrijkotte, Tanja Gm

2016-08-01

The purpose of this study was to examine the association of birth weight and infant growth with childhood autonomic nervous system (ANS) activity and to assess whether ANS activity mediates the associations of birth weight and infant growth with energy-balance-related behaviours, including energy intake, satiety response, physical activity and screen time. In 2089 children, we prospectively collected birth weight, infant growth defined as conditional weight and height gain between birth and 12 months and-at 5 years-indices of cardiac ANS activity and parent-reported energy-balance-related behaviours. A mediation analysis was conducted, based on MacKinnon's multivariate extension of the product-of-coefficients strategy. Birth weight and infant height gain were inversely associated with sympathetic, but not parasympathetic, activity at age 5. Infant weight gain was not associated with childhood ANS activity. Infant weight gain was predictive of increased childhood screen time and infant height gain of diminished childhood energy intake, but sympathetic activity did not mediate these associations. Low-birth-weight children have higher sympathetic activity, which is considered a risk factor for cardiovascular disease. Height gain in infancy seems to be beneficial for childhood sympathetic activity. However, sympathetic activity was no mediator of the associations of infant growth with childhood energy-balance-related behaviours. As individual differences in ANS activity predict increased risk of cardiovascular disease, these differences may offer insight into the early-life origins of chronic diseases and provide further basis for public health strategies to optimize birth weight and infant growth. © The Author 2016; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association.

Characterization of Candidate Solar Sail Material Exposed to Space Environmental Effects

NASA Technical Reports Server (NTRS)

Edwards, David; Hovater, Mary; Hubbs, Whitney; Wertz, George; Hollerman, William; Gray, Perry

2003-01-01

Solar sailing is a unique form of propulsion where a spacecraft gains momentum from incident photons. Solar sails are not limited by reaction mass and provide continual acceleration, reduced only by the lifetime of the lightweight film in the space environment and the distance to the Sun. Once thought to be difficult or impossible, solar sailing has come out of science fiction and into the realm of possibility. Any spacecraft using this method would need to deploy a thin sail that could be as large as many kilometers in extent. The availability of strong, ultra lightweight, and radiation resistant materials will determine the future of solar sailing. The National Aeronautics and Space Administration's Marshall Space Flight Center (MSFC) is concentrating research into the utilization of ultra lightweight materials for spacecraft propulsion. The Space Environmental Effects Team at MSFC is actively characterizing candidate solar sail material to evaluate the thermo-optical and mechanical properties after exposure to space environmental effects. This paper will describe the exposure of candidate solar sail materials to emulated space environmental effects including energetic electrons, combined electrons and Ultraviolet radiation, and hypervelocity impact of irradiated solar sail material. This paper will describe the testing procedure and the material characterization results of this investigation.

Influence of pre-pregnancy leisure time physical activity on gestational and postpartum weight gain and birth weight - a cohort study.

PubMed

Hegaard, Hanne Kristine; Rode, Line; Katballe, Malene Kjær; Langberg, Henning; Ottesen, Bent; Damm, Peter

2017-08-01

In order to examine the association between pre-pregnancy leisure time physical activities and gestational weight gain, postpartum weight gain and birth weight, we analysed prospectively collected data from 1827 women with singleton term pregnancies. Women were categorised in groups of sedentary women, light exercisers, moderate exercisers and competitive athletes. The results showed that sedentary women on average gained 14.1 kg during pregnancy, whereas light exercisers gained 13.7 kg, moderate exercisers gained 14.3 kg and competitive athletes 16.1 kg. Competitive athletes had an increased risk of having a gestational weight gain above Institute of Medicine (IOM) recommendations with an odds ratio of 2.60 (1.32-5.15) compared to light exercisers. However, birth weight and one year postpartum weight was similar for all four groups. Thus, although competitive athletes gain more weight than recommended during pregnancy, this may not affect birth weight or postpartum weight. Impact statement What is already known on this subjectPrevious studies have found that increased pre-pregnancy physical activity is associated with lower gestational weight gain during the last trimester, but showed no association between the pre-pregnancy level of physical activity and mean birth weight. What the results of this study addWe found that women classified as competitive exercisers had a 2.6-fold increased risk of gaining more weight than recommended compared to light exercisers. Nearly 6 out of 10 women among the competitive exercisers gained more weight than recommended by IOM. Surprisingly, this did not appear to increase birth weight or post-partum weight gain, but other adverse effects cannot be excluded. What the implications are of these findings for clinical practice and/or further researchIn the clinical practice it may be relevant to focus on and advise pre-pregnancy competitive exercisers in order to prevent excessive gestational weight gain.

The GOBLET training portal: a global repository of bioinformatics training materials, courses and trainers

PubMed Central

Corpas, Manuel; Jimenez, Rafael C.; Bongcam-Rudloff, Erik; Budd, Aidan; Brazas, Michelle D.; Fernandes, Pedro L.; Gaeta, Bruno; van Gelder, Celia; Korpelainen, Eija; Lewitter, Fran; McGrath, Annette; MacLean, Daniel; Palagi, Patricia M.; Rother, Kristian; Taylor, Jan; Via, Allegra; Watson, Mick; Schneider, Maria Victoria; Attwood, Teresa K.

2015-01-01

Summary: Rapid technological advances have led to an explosion of biomedical data in recent years. The pace of change has inspired new collaborative approaches for sharing materials and resources to help train life scientists both in the use of cutting-edge bioinformatics tools and databases and in how to analyse and interpret large datasets. A prototype platform for sharing such training resources was recently created by the Bioinformatics Training Network (BTN). Building on this work, we have created a centralized portal for sharing training materials and courses, including a catalogue of trainers and course organizers, and an announcement service for training events. For course organizers, the portal provides opportunities to promote their training events; for trainers, the portal offers an environment for sharing materials, for gaining visibility for their work and promoting their skills; for trainees, it offers a convenient one-stop shop for finding suitable training resources and identifying relevant training events and activities locally and worldwide. Availability and implementation: http://mygoblet.org/training-portal Contact: manuel.corpas@tgac.ac.uk PMID:25189782

Progress towards biocompatible intracortical microelectrodes for neural interfacing applications

NASA Astrophysics Data System (ADS)

Jorfi, Mehdi; Skousen, John L.; Weder, Christoph; Capadona, Jeffrey R.

2015-02-01

To ensure long-term consistent neural recordings, next-generation intracortical microelectrodes are being developed with an increased emphasis on reducing the neuro-inflammatory response. The increased emphasis stems from the improved understanding of the multifaceted role that inflammation may play in disrupting both biologic and abiologic components of the overall neural interface circuit. To combat neuro-inflammation and improve recording quality, the field is actively progressing from traditional inorganic materials towards approaches that either minimizes the microelectrode footprint or that incorporate compliant materials, bioactive molecules, conducting polymers or nanomaterials. However, the immune-privileged cortical tissue introduces an added complexity compared to other biomedical applications that remains to be fully understood. This review provides a comprehensive reflection on the current understanding of the key failure modes that may impact intracortical microelectrode performance. In addition, a detailed overview of the current status of various materials-based approaches that have gained interest for neural interfacing applications is presented, and key challenges that remain to be overcome are discussed. Finally, we present our vision on the future directions of materials-based treatments to improve intracortical microelectrodes for neural interfacing.

Progress Towards Biocompatible Intracortical Microelectrodes for Neural Interfacing Applications

PubMed Central

Jorfi, Mehdi; Skousen, John L.; Weder, Christoph; Capadona, Jeffrey R.

2015-01-01

To ensure long-term consistent neural recordings, next-generation intracortical microelectrodes are being developed with an increased emphasis on reducing the neuro-inflammatory response. The increased emphasis stems from the improved understanding of the multifaceted role that inflammation may play in disrupting both biologic and abiologic components of the overall neural interface circuit. To combat neuro-inflammation and improve recording quality, the field is actively progressing from traditional inorganic materials towards approaches that either minimizes the microelectrode footprint or that incorporate compliant materials, bioactive molecules, conducting polymers or nanomaterials. However, the immune-privileged cortical tissue introduces an added complexity compared to other biomedical applications that remains to be fully understood. This review provides a comprehensive reflection on the current understanding of the key failure modes that may impact intracortical microelectrode performance. In addition, a detailed overview of the current status of various materials-based approaches that have gained interest for neural interfacing applications is presented, and key challenges that remain to be overcome are discussed. Finally, we present our vision on the future directions of materials-based treatments to improve intracortical microelectrodes for neural interfacing. PMID:25460808

Exploring the dynamics of power: a Foucauldian analysis of care planning in learning disabilities services.

PubMed

Gilbert, Tony

2003-03-01

This paper draws upon a study completed in 2000 that focused upon health and welfare provision for people with learning disabilities in one English county. This study drew upon the theoretical insights of Michel Foucault to provide an analysis of the micro politics of care planning. This involved the analysis of text from two sources: the academic literature and interview material gained from a number of professionals working in health and welfare services for people with learning disabilities. Drawing upon this research material, the first part of this paper briefly explores the relationship between policy, professional practice and the people who are the subjects of that practice. The discussion then moves on to consider Foucault's five methodological precautions and the way power produces a localised web of activity that identifies specific targets for management. In this process power draws into the web a range of informal and formal practices that initially lie outside of the web. The discourse produced through the activity surrounding care planning provides the evidence of this flow of power. This discourse then takes on the status of science (truth), which reproduces this activity.

21 CFR 882.4100 - Ventricular catheter.

Code of Federal Regulations, 2012 CFR

2012-04-01

...) Identification. A ventricular catheter is a device used to gain access to the cavities of the brain for injection of material into, or removal of material from, the brain. (b) Classification. Class II (performance...

21 CFR 882.4100 - Ventricular catheter.

Code of Federal Regulations, 2013 CFR

2013-04-01

...) Identification. A ventricular catheter is a device used to gain access to the cavities of the brain for injection of material into, or removal of material from, the brain. (b) Classification. Class II (performance...

21 CFR 882.4100 - Ventricular catheter.

Code of Federal Regulations, 2011 CFR

2011-04-01

...) Identification. A ventricular catheter is a device used to gain access to the cavities of the brain for injection of material into, or removal of material from, the brain. (b) Classification. Class II (performance...

21 CFR 882.4100 - Ventricular catheter.

Code of Federal Regulations, 2014 CFR

2014-04-01

...) Identification. A ventricular catheter is a device used to gain access to the cavities of the brain for injection of material into, or removal of material from, the brain. (b) Classification. Class II (performance...

21 CFR 882.4100 - Ventricular catheter.

Code of Federal Regulations, 2010 CFR

2010-04-01

...) Identification. A ventricular catheter is a device used to gain access to the cavities of the brain for injection of material into, or removal of material from, the brain. (b) Classification. Class II (performance...

Expedition Earth and Beyond: Using NASA Data Resources and Integrated Educational Strategies to Promote Authentic Research in the Classroom

NASA Technical Reports Server (NTRS)

Graffi, Paige Valderrama; Stefanov, William; Willis, Kim; Runco, Sue

2009-01-01

Teachers in today s classrooms are bound by state required skills, education standards, and high stakes testing. How can they gain skills and confidence to replace units or individual activities with curriculum that incorporates project and inquiry-based learning and promotes authentic research in the classroom? The key to promoting classroom authentic research experiences lies in educator professional development that is structured around teacher needs. The Expedition Earth and Beyond Program is a new geosciences program based at the NASA Johnson Space Center designed to engage, inspire and educate teachers and students in grades 5-14. The program promotes authentic research experiences for classrooms and uses strategies that will help NASA reach its education goals while still allowing educators to teach required standards. Teachers will have access to experts in terrestrial and planetary remote sensing and geoscience; this will enhance their use of content, structure, and relevant experiences to gain the confidence and skills they need to actively engage students in authentic research experiences. Integrated and powerful educational strategies are used to build skills and confidence in teachers. The strategies are as follows: 1) creating Standards-aligned, inquiry-based curricular resources as ready-to-use materials that can be modified by teachers to fit their unique classroom situation; 2) providing ongoing professional development opportunities that focus on active experiences using curricular materials, inquiry-based techniques and expanding content knowledge; 3) connecting science experts to classrooms to deepen content knowledge and provide relevance to classroom activities and real world applications; 4) facilitating students sharing research with their peers and scientists reinforcing their active participation and contributions to research. These components of the Expedition Earth and Beyond Education Program will be enhanced by providing exciting and diverse research opportunities that are inspired by views of Earth from space taken by astronauts on board the International Space Station. The interest and connection to viewing our home planet from space will inevitably spark questions that will drive students to pursue their research investigations, as well as forming a basis for comparisons to the exploration of other planetary bodies in our solar system.

Expedition Earth and Beyond: Using NASA data resources and integrated educational strategies to promote authentic research in the classroom

NASA Astrophysics Data System (ADS)

Graff, P. V.; Stefanov, W.; Willis, K.; Runco, S.

2009-12-01

Teachers in today’s classrooms are bound by state required skills, education standards, and high stakes testing. How can they gain skills and confidence to replace units or individual activities with curriculum that incorporates project and inquiry-based learning and promotes authentic research in the classroom? The key to promoting classroom authentic research experiences lies in educator professional development that is structured around teacher needs. The Expedition Earth and Beyond Program is a new geosciences program based at the NASA Johnson Space Center designed to engage, inspire and educate teachers and students in grades 5-14. The program promotes authentic research experiences for classrooms and uses strategies that will help NASA reach its education goals while still allowing educators to teach required standards. Teachers will have access to experts in terrestrial and planetary remote sensing and geoscience; this will enhance their use of content, structure, and relevant experiences to gain the confidence and skills they need to actively engage students in authentic research experiences. Integrated and powerful educational strategies are used to build skills and confidence in teachers. The strategies are as follows: 1) creating Standards-aligned, inquiry-based curricular resources as ready-to-use materials that can be modified by teachers to fit their unique classroom situation; 2) providing ongoing professional development opportunities that focus on active experiences using curricular materials, inquiry-based techniques and expanding content knowledge; 3) connecting science experts to classrooms to deepen content knowledge and provide relevance to classroom activities and real world applications; 4) facilitating students sharing research with their peers and scientists reinforcing their active participation and contributions to research. These components of the Expedition Earth and Beyond Education Program will be enhanced by providing exciting and diverse research opportunities that are inspired by views of Earth from space taken by astronauts on board the International Space Station. The interest and connection to viewing our home planet from space will inevitably spark questions that will drive students to pursue their research investigations, as well as forming a basis for comparisons to the exploration of other planetary bodies in our solar system.

Nonlinear ordinary difference equations

NASA Technical Reports Server (NTRS)

Caughey, T. K.

1979-01-01

Future space vehicles will be relatively large and flexible, and active control will be necessary to maintain geometrical configuration. While the stresses and strains in these space vehicles are not expected to be excessively large, their cumulative effects will cause significant geometrical nonlinearities to appear in the equations of motion, in addition to the nonlinearities caused by material properties. Since the only effective tool for the analysis of such large complex structures is the digital computer, it will be necessary to gain a better understanding of the nonlinear ordinary difference equations which result from the time discretization of the semidiscrete equations of motion for such structures.

Nanotechnologies in Cuba: Popularization and Training

NASA Astrophysics Data System (ADS)

Rodríguez Castellanos, Carlos

In Cuba, as in other countries, activities in the field of nanotechnology emerged from the converging development of research in materials physics and chemistry, microelectronics, supramolecular physics, microbiology and molecular biology. During the 1990s, theoretical and experimental work on semiconductor nanostructures gained in importance. Cuban physicists organized the Red CYTED (Network CYTED) to "study fabrication and characterization of semiconductor nanostructures for micro and optoelectronics" which functioned between 1998 and 2003 with the participation of eight Spanish-American countries. The network organized various courses and scientific meetings, edited a book and supported the scientific collaboration among the participant institutions.

Caanyon Mediated Cross-Slope Transport

NASA Astrophysics Data System (ADS)

Mihaly, S. F.; Cabrera De Leo, F.; Sastri, A. R.; Matabos, M.; Heesemann, M.; Ogata, B.

2017-12-01

Three current meter and water property stations along the west coast of Vancouver Island along with video and acoustic backscatter observations are used to gain insight into mechanisms of cross-slope transport. The setting is an eastern boundary current region with a active poleward flowing countercurrent. The significant effects of these currents flowing over a strongly incised continental slope along with cross-slope density flows are contrasted with the seasonally varying upwelling and downwelling regime. The video and acoustic backscatter enabled by Ocean Networks Canada's NEPTUNE observatory provide a view on the materials being transported between the abyssal plain and the continental shelf.

Annual Progress Report of Research Activities that Occured in the Coordinated Science Laboratory for July 1, 1982 through Jun 30, 1983,

DTIC Science & Technology

1983-08-01

particular fabrication concerns, both the emitter and collector region were made of Al„ -Ga0 5As wide gap material. Devices with emitter area of 10 x 60...im and collector area of 50 x 60 (im exhi- bited current gains of 500 for a base doping of 10 cm and thickness of 500 A, and 1700 for a base...spreading over a large enough distance, it is usually necessary to heat the surface to a temperature at which not just diffusion, but also

Ultrasensitive photodetectors exploiting electrostatic trapping and percolation transport

DOE PAGES

Zhang, Yingjie; Hellebusch, Daniel J.; Bronstein, Noah D.; ...

2016-06-21

The sensitivity of semiconductor photodetectors is limited by photocarrier recombination during the carrier transport process. We developed a new photoactive material that reduces recombination by physically separating hole and electron charge carriers. This material has a specific detectivity (the ability to detect small signals) of 5 × 10 17 Jones, the highest reported in visible and infrared detectors at room temperature, and 4-5 orders of magnitude higher than that of commercial single-crystal silicon detectors. The material was fabricated by sintering chloride-capped CdTe nanocrystals into polycrystalline films, where Cl selectively segregates into grain boundaries acting as n-type dopants. Photogenerated electrons concentratemore » in and percolate along the grain boundaries - a network of energy valleys, while holes are confined in the grain interiors. This electrostatic field-assisted carrier separation and percolation mechanism enables an unprecedented photoconductive gain of 10 10 e - per photon, and allows for effective control of the device response speed by active carrier quenching.« less

Applications of XPS in the characterization of Battery materials

DOE PAGES

Shutthanandan, Vaithiyalingam; Nandasiri, Manjula; Zheng, Jianming; ...

2018-05-26

In this study, technological development requires reliable power sources where energy storage devices are emerging as a critical component. Wide range of energy storage devices, Redox-flow batteries (RFB), Lithium ion based batteries (LIB), and Lithium-sulfur (LSB) batteries are being developed for various applications ranging from grid-scale level storage to mobile electronics. Material complexities associated with these energy storage devices with unique electrochemistry are formidable challenge which needs to be address for transformative progress in this field. X-ray photoelectron spectroscopy (XPS) - a powerful surface analysis tool - has been widely used to study these energy storage materials because of itsmore » ability to identify, quantify and image the chemical distribution of redox active species. However, accessing the deeply buried solid-electrolyte interfaces (which dictates the performance of energy storage devices) has been a challenge in XPS usage. Herein we report our recent efforts to utilize the XPS to gain deep insight about these interfaces under realistic conditions with varying electrochemistry involving RFB, LIB and LSB.« less

Ultrasensitive photodetectors exploiting electrostatic trapping and percolation transport

PubMed Central

Zhang, Yingjie; Hellebusch, Daniel J.; Bronstein, Noah D.; Ko, Changhyun; Ogletree, D. Frank; Salmeron, Miquel; Alivisatos, A. Paul

2016-01-01

The sensitivity of semiconductor photodetectors is limited by photocarrier recombination during the carrier transport process. We developed a new photoactive material that reduces recombination by physically separating hole and electron charge carriers. This material has a specific detectivity (the ability to detect small signals) of 5 × 1017 Jones, the highest reported in visible and infrared detectors at room temperature, and 4–5 orders of magnitude higher than that of commercial single-crystal silicon detectors. The material was fabricated by sintering chloride-capped CdTe nanocrystals into polycrystalline films, where Cl selectively segregates into grain boundaries acting as n-type dopants. Photogenerated electrons concentrate in and percolate along the grain boundaries—a network of energy valleys, while holes are confined in the grain interiors. This electrostatic field-assisted carrier separation and percolation mechanism enables an unprecedented photoconductive gain of 1010 e− per photon, and allows for effective control of the device response speed by active carrier quenching. PMID:27323904

Resource recovery from urban stock, the example of cadmium and tellurium from thin film module recycling.

PubMed

Simon, F-G; Holm, O; Berger, W

2013-04-01

Raw material supply is essential for all industrial activities. The use of secondary raw material gains more importance since ore grade in primary production is decreasing. Meanwhile urban stock contains considerable amounts of various elements. Photovoltaic (PV) generating systems are part of the urban stock and recycling technologies for PV thin film modules with CdTe as semiconductor are needed because cadmium could cause hazardous environmental impact and tellurium is a scarce element where future supply might be constrained. The paper describes a sequence of mechanical processing techniques for end-of-life PV thin film modules consisting of sandblasting and flotation. Separation of the semiconductor material from the glass surface was possible, however, enrichment and yield of valuables in the flotation step were non-satisfying. Nevertheless, recovery of valuable metals from urban stock is a viable method for the extension of the availability of limited natural resources. Copyright © 2013 Elsevier Ltd. All rights reserved.

Applications of XPS in the characterization of Battery materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shutthanandan, Vaithiyalingam; Nandasiri, Manjula; Zheng, Jianming

In this study, technological development requires reliable power sources where energy storage devices are emerging as a critical component. Wide range of energy storage devices, Redox-flow batteries (RFB), Lithium ion based batteries (LIB), and Lithium-sulfur (LSB) batteries are being developed for various applications ranging from grid-scale level storage to mobile electronics. Material complexities associated with these energy storage devices with unique electrochemistry are formidable challenge which needs to be address for transformative progress in this field. X-ray photoelectron spectroscopy (XPS) - a powerful surface analysis tool - has been widely used to study these energy storage materials because of itsmore » ability to identify, quantify and image the chemical distribution of redox active species. However, accessing the deeply buried solid-electrolyte interfaces (which dictates the performance of energy storage devices) has been a challenge in XPS usage. Herein we report our recent efforts to utilize the XPS to gain deep insight about these interfaces under realistic conditions with varying electrochemistry involving RFB, LIB and LSB.« less

Advanced Na-NiCl2 Battery Using Nickel-Coated Graphite with Core-Shell Microarchitecture.

PubMed

Chang, Hee-Jung; Canfield, Nathan L; Jung, Keeyoung; Sprenkle, Vincent L; Li, Guosheng

2017-04-05

Stationary electric energy storage devices (rechargeable batteries) have gained increasing prominence due to great market needs, such as smoothing the fluctuation of renewable energy resources and supporting the reliability of the electric grid. With regard to raw materials availability, sodium-based batteries are better positioned than lithium batteries due to the abundant resource of sodium in Earth's crust. However, the sodium-nickel chloride (Na-NiCl 2 ) battery, one of the most attractive stationary battery technologies, is hindered from further market penetration by its high material cost (Ni cost) and fast material degradation at its high operating temperature. Here, we demonstrate the design of a core-shell microarchitecture, nickel-coated graphite, with a graphite core to maintain electrochemically active surface area and structural integrity of the electron percolation pathway while using 40% less Ni than conventional Na-NiCl 2 batteries. An initial energy density of 133 Wh/kg (at ∼C/4) and energy efficiency of 94% are achieved at an intermediate temperature of 190 °C.

Atomic Scale Understanding of Poly-Si/SiO2/c-Si Passivated Contacts: Passivation Degradation Due to Metallization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aguiar, Jeffery A.; Young, David; Lee, Benjamin

2016-11-21

The key attributes for achieving high efficiency crystalline silicon solar cells include class leading developments in the ability to approach the theoretical limits of silicon solar technology (29.4% efficiency). The push for high efficiency devices is further compounded with the clear need for passivation to reduce recombination at the metal contacts. At the same time there is stringent requirement to retain the same material device quality, surface passivation, and performance characteristics following subsequent processing. The development of passivated silicon cell structures that retain active front and rear surface passivation and overall material cell quality is therefore a relevant and activemore » area of development. To address the potential outcomes of metallization on passivated silicon stack, we report on some common microstructural features of degradation due to metallization for a series of silicon device stacks. A fundamental materials understanding of the metallization process on retaining high-efficiency passivated Si devices is therefore gained over these series of results.« less

Improved Student Learning through a Faculty Learning Community: How Faculty Collaboration Transformed a Large-Enrollment Course from Lecture to Student Centered.

PubMed

Elliott, Emily R; Reason, Robert D; Coffman, Clark R; Gangloff, Eric J; Raker, Jeffrey R; Powell-Coffman, Jo Anne; Ogilvie, Craig A

2016-01-01

Undergraduate introductory biology courses are changing based on our growing understanding of how students learn and rapid scientific advancement in the biological sciences. At Iowa State University, faculty instructors are transforming a second-semester large-enrollment introductory biology course to include active learning within the lecture setting. To support this change, we set up a faculty learning community (FLC) in which instructors develop new pedagogies, adapt active-learning strategies to large courses, discuss challenges and progress, critique and revise classroom interventions, and share materials. We present data on how the collaborative work of the FLC led to increased implementation of active-learning strategies and a concurrent improvement in student learning. Interestingly, student learning gains correlate with the percentage of classroom time spent in active-learning modes. Furthermore, student attitudes toward learning biology are weakly positively correlated with these learning gains. At our institution, the FLC framework serves as an agent of iterative emergent change, resulting in the creation of a more student-centered course that better supports learning. © 2016 E. R. Elliott et al. CBE—Life Sciences Education © 2016 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Materials Development in the Colombian Context: Some Considerations about Its Benefits and Challenges

ERIC Educational Resources Information Center

Ramos Holguín, Bertha; Aguirre Morales, Jahir

2014-01-01

Materials development is a field of study which has recently acquired significant importance in the Colombian context due to the fact that teachers, as materials developers, consider materials development as an area of knowledge that helps them to improve their teaching practices. However, the rationale, the gains as well as the challenges that…

Effect of nanodiamond modification of siloxane surfaces on stem cell behaviour

NASA Astrophysics Data System (ADS)

Keremidarska, M.; Hikov, T.; Radeva, E.; Pramatarova, L.; Krasteva, N.

2014-12-01

Mesenchymal stem cells (MSCs) hold a great promise for use in many cell therapies and tissue engineering due to their remarkable potential to replicate indefinitely and differentiate into various cell types. Many efforts have been put to study the factors controlling stem cell differentiation. However, still little knowledge has been gained to what extent biomaterials properties influence stem cell adhesion, growth and differentiation. Research utilizing bone marrow-derived MSCs has concentrated on development of specific materials which can enhance specific differentiation of stem cells e.g. osteogenic and chondrogenic. In the present work we have modified an organosilane, hexamethyldisiloxane (HMDS) with detonation nanodiamond (DND) particles aiming to improve adhesion, growth and osteodifferentiation of rat mesenchymal stem cells. HMDS/DND films were deposited on cover glass using two approaches: premixing of both compounds, followed by plasma polymerization (PP) and PP of HMDS followed by plasma deposition of DND particles. We did not observe however an increase in rMSCs adhesion and growth on DND-modified PPHMDS surfaces compared to unmodified PPHMDS. When we studied alkaline phosphatase (ALP) activity, which is a major sign for early osteodifferentiation, we found the highest ALP activity on the PPHMDS/DND material, prepared by consequent deposition while on the other composite material ALP activity was the lowest. These results suggested that DND-modified materials were able to control osteodifferention in MSCs depending on the deposition approach. Modification of HMDS with DND particles by consequent plasma deposition seems to be a promising approach to produce biomaterials capable to guide stem cell differentiation toward osteoblasts and thus to be used in bone tissue engineering.

Rotationally induced surface slope-instabilities and the activation of CO2 activity on comet 103P/Hartley 2

NASA Astrophysics Data System (ADS)

Steckloff, Jordan K.; Graves, Kevin; Hirabayashi, Masatoshi; Melosh, H. Jay; Richardson, James E.

2016-07-01

Comet 103P/Hartley 2 has diurnally controlled, CO2-driven activity on the tip of the small lobe of its bilobate nucleus. Such activity is unique among the comet nuclei visited by spacecraft, and suggests that CO2 ice is very near the surface, which is inconsistent with our expectations of an object that thermophysically evolved for ∼45 million years prior to entering the Jupiter Family of comets. Here we explain this pattern of activity by showing that a very plausible recent episode of rapid rotation (rotation period of ∼11 [10-13] h) would have induced avalanches in Hartley 2's currently active regions that excavated down to CO2-rich ices and activated the small lobe of the nucleus. At Hartley 2's current rate of spindown about its principal axis, the nucleus would have been spinning fast enough to induce avalanches ∼3-4 orbits prior to the DIXI flyby (∼1984-1991). This coincides with Hartley 2's discovery in 1986, and implies that the initiation of CO2 activity facilitated the comet's discovery. During the avalanches, the sliding material would either be lofted off the surface by gas activity, or possibly gained enough momentum moving downhill (toward the tip of the small lobe) to slide off the tip of the small lobe. Much of this material would have failed to reach escape velocity, and would reimpact the nucleus, forming debris deposits. The similar size frequency distribution of the mounds observed on the surface of Hartley 2 and chunks of material in its inner coma suggest that the 20-40 m mounds observed by the DIXI mission on the surface of Hartley 2 are potentially these fallback debris deposits. As the nucleus spun down (rotation period increased) from a period of ∼11-18.34 h at the time of the DIXI flyby, the location of potential minima, where materials preferentially settle, migrated about the surface, allowing us to place relative ages on most of the terrains on the imaged portion of the nucleus.

NORM -- The new kid on the block

DOE Office of Scientific and Technical Information (OSTI.GOV)

Estey, H.P.

1991-12-31

The existence of radioactive materials in accumulations of scale and sludge in oil and gas production equipment is a relatively new issue. This developing issue first gained international attention in 1981 when significant radiation levels were detected on oil and gas production platforms in the North Sea; it didn`t become a domestic issue until 1986 when a similar situation was detected in a Mississippi pipe yard. Most published papers on the occurrence of Naturally Occurring Radioactive Materials (NORM) in oil and gas production equipment have been based on studies of NORM-related activities in the United Kingdom (North Sea NORM). Thismore » paper addresses the occurrences and regulation of NORM in the US oil and gas production industry as experienced, witnessed and/or observed by the author over the past four years.« less

Amplification and gas-dynamic parameters of the active oxygen-iodine medium produced by an ejector nozzle unit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zagidullin, M V; Nikolaev, V D; Svistun, M I

2001-08-31

The gain, the temperature, and the absolute velocity of the supersonic active oxygen-iodine medium produced by an ejector nozzle unit were determined by the technique of high-resolution diode laser spectroscopy. The gain in the active medium is formed at less than 44 mm from the nozzle unit for an absolute flow velocity {nu} {approx} 600 m s{sup -1}. Upon dilution of oxygen by primary nitrogen in the ratio of 1 : 6.9, the gain of the active medium amounts to 7x10{sup -3} cm{sup -1}, the temperature of the active medium to 200 K, the absolute flow velocity to 580 mmore » s{sup -1}, and the pressure to 58 Torr. As the dilution is increased to 1 : 13.5, the gain reduces to 4.5x10{sup -3} cm{sup -1}, the temperature lowers to 180 K, the velocity of the active medium increases to 615 m s{sup -1}, and the pressure increases to 88 Torr. The increase in the initial content of water vapour in the oxygen flow results in an increase in the temperature and a decrease in the gain of the active medium. (active media)« less

Time-varying phononic crystals

NASA Astrophysics Data System (ADS)

Wright, Derek Warren

The primary objective of this thesis was to gain a deeper understanding of acoustic wave propagation in phononic crystals, particularly those that include materials whose properties can be varied periodically in time. This research was accomplished in three ways. First, a 2D phononic crystal was designed, created, and characterized. Its properties closely matched those determined through simulation. The crystal demonstrated band gaps, dispersion, and negative refraction. It served as a means of elucidating the practicalities of phononic crystal design and construction and as a physical verification of their more interesting properties. Next, the transmission matrix method for analyzing 1D phononic crystals was extended to include the effects of time-varying material parameters. The method was then used to provide a closed-form solution for the case of periodically time-varying material parameters. Some intriguing results from the use of the extended method include dramatically altered transmission properties and parametric amplification. New insights can be gained from the governing equations and have helped to identify the conditions that lead to parametric amplification in these structures. Finally, 2D multiple scattering theory was modified to analyze scatterers with time-varying material parameters. It is shown to be highly compatible with existing multiple scattering theories. It allows the total scattered field from a 2D time-varying phononic crystal to be determined. It was shown that time-varying material parameters significantly affect the phononic crystal transmission spectrum, and this was used to switch an incident monochromatic wave. Parametric amplification can occur under certain circumstances, and this effect was investigated using the closed-form solutions provided by the new 1D method. The complexity of the extended methods grows logarithmically as opposed linearly with existing methods, resulting in superior computational complexity for large numbers of scatterers. Also, since both extended methods provide analytic solutions, they may give further insights into the factors that govern the behaviour of time-varying phononic crystals. These extended methods may now be used to design an active phononic crystal that could demonstrate new or enhanced properties.

Purification and characterization of a cold-active lipase from Pichia lynferdii Y-7723: pH-dependant activity deviation

USDA-ARS?s Scientific Manuscript database

Lipases with abnormal functionalities such as high thermostability and optimal activity at extreme conditions gain special attentions because of their applicability in the restricted reaction conditions. In particular, cold-active lipases have gained special attentions in various industrial fields s...

Mechanisms of Gain Control by Voltage-Gated Channels in Intrinsically-Firing Neurons

PubMed Central

Patel, Ameera X.; Burdakov, Denis

2015-01-01

Gain modulation is a key feature of neural information processing, but underlying mechanisms remain unclear. In single neurons, gain can be measured as the slope of the current-frequency (input-output) relationship over any given range of inputs. While much work has focused on the control of basal firing rates and spike rate adaptation, gain control has been relatively unstudied. Of the limited studies on gain control, some have examined the roles of synaptic noise and passive somatic currents, but the roles of voltage-gated channels present ubiquitously in neurons have been less explored. Here, we systematically examined the relationship between gain and voltage-gated ion channels in a conductance-based, tonically-active, model neuron. Changes in expression (conductance density) of voltage-gated channels increased (Ca2+ channel), reduced (K+ channels), or produced little effect (h-type channel) on gain. We found that the gain-controlling ability of channels increased exponentially with the steepness of their activation within the dynamic voltage window (voltage range associated with firing). For depolarization-activated channels, this produced a greater channel current per action potential at higher firing rates. This allowed these channels to modulate gain by contributing to firing preferentially at states of higher excitation. A finer analysis of the current-voltage relationship during tonic firing identified narrow voltage windows at which the gain-modulating channels exerted their effects. As a proof of concept, we show that h-type channels can be tuned to modulate gain by changing the steepness of their activation within the dynamic voltage window. These results show how the impact of an ion channel on gain can be predicted from the relationship between channel kinetics and the membrane potential during firing. This is potentially relevant to understanding input-output scaling in a wide class of neurons found throughout the brain and other nervous systems. PMID:25816008

Active rc filter permits easy trade-off of amplifier gain and sensitivity to gain

NASA Technical Reports Server (NTRS)

Kerwin, W. J.; Shaffer, C. V.

1968-01-01

Passive RC network was designed with zeros of transmission in the right half of the complex frequency plane in the feedback loop of a simple negative-gain amplifier. The proper positioning provides any desired trade-off between amplifier gain and sensitivity to amplifier gain.

Kinetics of the Active Medium of a Copper Vapor Brightness Amplifier

NASA Astrophysics Data System (ADS)

Kulagin, A. E.; Torgaev, S. N.; Evtushenko, G. S.; Trigub, M. V.

2018-03-01

A spatiotemporal kinetics of the active medium of a copper vapor brightness amplifier is described that allows gain characteristics to be investigated during the pump pulse. Model calculations show that changing the discharge parameters allows the radial gain profiles to be improved significantly, as well as the gain and the inversion duration to be increased. The data obtained will be used to choose the operating conditions for the active medium in the brightness amplifier mode.

Hint of Universal Law for the Financial Gains of Competitive Sport Teams. The case of Tour de France cycle race.

NASA Astrophysics Data System (ADS)

Ausloos, Marcel

2017-12-01

This short note is intended as a "Letter to the Editor" Perspective in order that it serves as a contribution, in view of reaching the physics community caring about rare events and scaling laws and unexpected findings, on a domain of wide interest: sport and money. It is apparent from the data reported and discussed below that the scarcity of such data does not allow to recommend a complex elaboration of an agent based model, - at this time. In some sense, this also means that much data on sport activities is not necessarily given in terms of physics prone materials, but it could be, and would then attract much attention. Nevertheless the findings tie the data to well known scaling laws and physics processes. It is found that a simple scaling law describes the gains of teams in recent bicycle races, like the Tour de France. An analogous case, ranking teams in Formula 1 races, is shown in an Appendix

Advances and directions of ion nitriding/carburizing

NASA Technical Reports Server (NTRS)

Spalvins, Talivaldis

1989-01-01

Ion nitriding and carburizing are plasma activated thermodynamic processes for the production of case hardened surface layers not only for ferrous materials, but also for an increasing number of nonferrous metals. When the treatment variables are properly controlled, the use of nitrogenous or carbonaceous glow discharge medium offers great flexibility in tailoring surface/near-surface properties independently of the bulk properties. The ion nitriding process has reached a high level of maturity and has gained wide industrial acceptance, while the more recently introduced ion carburizing process is rapidly gaining industrial acceptance. The current status of plasma mass transfer mechanisms into the surface regarding the formation of compound and diffusion layers in ion nitriding and carbon build-up ion carburizing is reviewed. In addition, the recent developments in design and construction of advanced equipment for obtaining optimized and controlled case/core properties is summarized. Also, new developments and trends such as duplex plasma treatments and alternatives to dc diode nitriding are highlighted.

Negative refraction, gain and nonlinear effects in hyperbolic metamaterials.

PubMed

Argyropoulos, Christos; Estakhri, Nasim Mohammadi; Monticone, Francesco; Alù, Andrea

2013-06-17

The negative refraction and evanescent-wave canalization effects supported by a layered metamaterial structure obtained by alternating dielectric and plasmonic layers is theoretically analyzed. By using a transmission-line analysis, we formulate a way to rapidly analyze the negative refraction operation for given available materials over a broad range of frequencies and design parameters, and we apply it to broaden the bandwidth of negative refraction. Our analytical model is also applied to explore the possibility of employing active layers for loss compensation. Nonlinear dielectrics can also be considered within this approach, and they are explored in order to add tunability to the optical response, realizing positive-to-zero-to-negative refraction at the same frequency, as a function of the input intensity. Our findings may lead to a better physical understanding and improvement of the performance of negative refraction and subwavelength imaging in layered metamaterials, paving the way towards the design of gain-assisted hyperlenses and tunable nonlinear imaging devices.

Active Learning in the Physics Classroom

NASA Astrophysics Data System (ADS)

Naron, Carol

Many students enter physics classes filled with misconceptions about physics concepts. Students tend to retain these misconceptions into their adult lives, even after physics instruction. Constructivist researchers have found that students gain understanding through their experiences. Researchers have also found that active learning practices increase conceptual understanding of introductory physics students. This project study sought to examine whether incorporating active learning practices in an advanced placement physics classroom increased conceptual understanding as measured by the force concept inventory (FCI). Physics students at the study site were given the FCI as both a pre- and posttest. Test data were analyzed using two different methods---a repeated-measures t test and the Hake gain method. The results of this research project showed that test score gains were statistically significant, as measured by the t test. The Hake gain results indicated a low (22.5%) gain for the class. The resulting project was a curriculum plan for teaching the mechanics portion of Advanced Placement (AP) physics B as well as several active learning classroom practices supported by the research. This project will allow AP physics teachers an opportunity to improve their curricular practices. Locally, the results of this project study showed that research participants gained understanding of physics concepts. Social change may occur as teachers implement active learning strategies, thus creating improved student understanding of physics concepts.

Digital education and dynamic assessment of tongue diagnosis based on Mashup technique.

PubMed

Tsai, Chin-Chuan; Lo, Yen-Cheng; Chiang, John Y; Sainbuyan, Natsagdorj

2017-01-24

To assess the digital education and dynamic assessment of tongue diagnosis based on Mashup technique (DEDATD) according to specifific user's answering pattern, and provide pertinent information tailored to user's specifific needs supplemented by the teaching materials constantly updated through the Mashup technique. Fifty-four undergraduate students were tested with DEDATD developed. The effificacy of the DEDATD was evaluated based on the pre- and post-test performance, with interleaving training sessions targeting on the weakness of the student under test. The t-test demonstrated that signifificant difference was reached in scores gained during pre- and post-test sessions, and positive correlation between scores gained and length of time spent on learning, while no signifificant differences between the gender and post-test score, and the years of students in school and the progress in score gained. DEDATD, coupled with Mashup technique, could provide updated materials fifiltered through diverse sources located across the network. The dynamic assessment could tailor each individual learner's needs to offer custom-made learning materials. DEDATD poses as a great improvement over the traditional teaching methods.

Active mode-locking of mid-infrared quantum cascade lasers with short gain recovery time.

PubMed

Wang, Yongrui; Belyanin, Alexey

2015-02-23

We investigate the dynamics of actively modulated mid-infrared quantum cascade lasers (QCLs) using space- and time-domain simulations of coupled density matrix and Maxwell equations with resonant tunneling current taken into account. We show that it is possible to achieve active mode locking and stable generation of picosecond pulses in high performance QCLs with a vertical laser transition and a short gain recovery time by bias modulation of a short section of a monolithic Fabry-Perot cavity. In fact, active mode locking in QCLs with a short gain recovery time turns out to be more robust to the variation of parameters as compared to previously studied lasers with a long gain recovery time. We investigate the effects of spatial hole burning and phase locking on the laser output.

A multiscale-based approach for composite materials with embedded PZT filaments for energy harvesting

NASA Astrophysics Data System (ADS)

El-Etriby, Ahmed E.; Abdel-Meguid, Mohamed E.; Hatem, Tarek M.; Bahei-El-Din, Yehia A.

2014-03-01

Ambient vibrations are major source of wasted energy, exploiting properly such vibration can be converted to valuable energy and harvested to power up devices, i.e. electronic devices. Accordingly, energy harvesting using smart structures with active piezoelectric ceramics has gained wide interest over the past few years as a method for converting such wasted energy. This paper provides numerical and experimental analysis of piezoelectric fiber based composites for energy harvesting applications proposing a multi-scale modeling approach coupled with experimental verification. The multi-scale approach suggested to predict the behavior of piezoelectric fiber-based composites use micromechanical model based on Transformation Field Analysis (TFA) to calculate the overall material properties of electrically active composite structure. Capitalizing on the calculated properties, single-phase analysis of a homogeneous structure is conducted using finite element method. The experimental work approach involves running dynamic tests on piezoelectric fiber-based composites to simulate mechanical vibrations experienced by a subway train floor tiles. Experimental results agree well with the numerical results both for static and dynamic tests.

Temperature-insensitive vertical-cavity surface-emitting lasers and method for fabrication thereof

DOEpatents

Chow, W.W.; Choquette, K.D.; Gourley, P.L.

1998-01-27

A temperature-insensitive vertical-cavity surface-emitting laser (VCSEL) and method for fabrication thereof are disclosed. The temperature-insensitive VCSEL comprises a quantum-well active region within a resonant cavity, the active region having a gain spectrum with a high-order subband (n {>=} 2) contribution thereto for broadening and flattening the gain spectrum, thereby substantially reducing any variation in operating characteristics of the VCSEL over a temperature range of interest. The method for forming the temperature-insensitive VCSEL comprises the steps of providing a substrate and forming a plurality of layers thereon for providing first and second distributed Bragg reflector (DBR) mirror stacks with an active region sandwiched therebetween, the active region including at least one quantum-well layer providing a gain spectrum having a high-order subband (n {>=} 2) gain contribution, and the DBR mirror stacks having predetermined layer compositions and thicknesses for providing a cavity resonance within a predetermined wavelength range substantially overlapping the gain spectrum. 12 figs.

Temperature-insensitive vertical-cavity surface-emitting lasers and method for fabrication thereof

DOEpatents

Chow, Weng W.; Choquette, Kent D.; Gourley, Paul L.

1998-01-01

A temperature-insensitive vertical-cavity surface-emitting laser (VCSEL) and method for fabrication thereof. The temperature-insensitive VCSEL comprises a quantum-well active region within a resonant cavity, the active region having a gain spectrum with a high-order subband (n.gtoreq.2) contribution thereto for broadening and flattening the gain spectrum, thereby substantially reducing any variation in operating characteristics of the VCSEL over a temperature range of interest. The method for forming the temperature-insensitive VCSEL comprises the steps of providing a substrate and forming a plurality of layers thereon for providing first and second distributed Bragg reflector (DBR) mirror stacks with an active region sandwiched therebetween, the active region including at least one quantum-well layer providing a gain spectrum having a high-order subband (n.gtoreq.2) gain contribution, and the DBR mirror stacks having predetermined layer compositions and thicknesses for providing a cavity resonance within a predetermined wavelength range substantially overlapping the gain spectrum.

A qualitative examination of perceptions of physical activity guidelines and preferences for format.

PubMed

Berry, Tanya R; Witcher, Chad; Holt, Nicholas L; Plotnikoff, Ronald C

2010-11-01

A descriptive exploratory study was conducted to gain an understanding of public perceptions of physical activity guidelines and to discover what formats appeal to participants. Canada's Physical Activity Guide (CPAG) was used as an example of such guidelines. Data were collected from 22 participants in five focus groups (composed of female undergraduate students, female office workers, male office workers, participants in a Type II diabetes rehabilitation program, and participants in a cardiovascular rehabilitation program). Cross-case qualitative analyses were conducted. Six themes emerged under the general categories of familiarity and preferences for PA promotional materials. In terms of familiarity, participants lacked awareness of CPAG and criticized its format. In terms of preferences, participants encouraged the use of stylistically similar messaging to those used by commercial advertisers, wanted personal stories, Internet-based media, and the use of celebrities' success stories. There was little awareness of CPAG and the current format was unappealing.

New Material Saves School Dollars.

ERIC Educational Resources Information Center

School Business Affairs, 1984

1984-01-01

Hobbs Window Insulation, an inexpensive polyester material, can reduce heat loss or gain through single-pane glass by 70 percent. The product is translucent, has an insulative value of R-3, and is easy to install and remove. (MCG)

Multiscale Materials Modeling Workshop Summary

DOT National Transportation Integrated Search

2013-12-01

This report summarizes a 2-day workshop held to share information on multiscale material modeling. The aim was to gain expert feedback on the state of the art and identify Exploratory Advanced Research (EAR) Program opportunities for multiscale mater...

Deformation and annealing study of Nicraly

NASA Technical Reports Server (NTRS)

Trela, D. M.; Ebert, L. J.

1975-01-01

Extensive experiments were carried out on the ODS alloy Nicraly, (an alloy prepared by mechanical alloying and consolidating a powder blend consisting of 16% chromium, 4% aluminum, 2-3% yttria, balance nickel), in efforts to develop methods of controlling the grain size and grain shape of the material. The experiments fell into two general categories: variations in the annealing parameters using the as-extruded material as it was received, and various thermomechanical processing schedules (various combinations of cold work and annealing). Success was achieved in gaining grain size and grain shape control by annealing of the as-extruded material. By proper selection of annealing temperature and cooling rates, the grain size of the as-received material was increased almost two orders of magnitude (from an average grain dimension of 0.023 mm to 1.668 mm) while the aspect ratio was increased by some 50% (from 20:1 to 30:1). No success was achieved in gaining significant control of the grain size and shape of the material by thermo-mechanical processing.

High Velocity Burner Rig Oxidation and Thermal Fatigue Behavior of Si3N4- and SiC Base Ceramics to 1370 Deg C

NASA Technical Reports Server (NTRS)

Sanders, W. A.; Johnston, J. R.

1978-01-01

One SiC material and three Si3N4 materials including hot-pressed Si3N4 as a baseline were exposed in a Mach-1-gas-velocity burner rig simulating a turbine engine environment. Criteria for the materials selection were: potential for gas-turbine usage, near-net-shape fabricability and commercial/domestic availability. Cyclic exposures of test vanes up to 250 cycles (50 hr at temperature) were at leading-edge temperatures to 1370 C. Materials and batches were compared as to weight change, surface change, fluorescent penetrant inspection, and thermal fatigue behavior. Hot-pressed Si3N4 survived the test to 1370 C with slight weight losses. Two types of reaction-sintered Si3N4 displayed high weight gains and considerable weight-change variability, with one material exhibiting superior thermal fatigue behavior. A siliconized SiC showed slight weight gains, but considerable batch variability in thermal fatigue.

Transient shifts in frontal and parietal circuits scale with enhanced visual feedback and changes in force variability and error

PubMed Central

Poon, Cynthia; Coombes, Stephen A.; Corcos, Daniel M.; Christou, Evangelos A.

2013-01-01

When subjects perform a learned motor task with increased visual gain, error and variability are reduced. Neuroimaging studies have identified a corresponding increase in activity in parietal cortex, premotor cortex, primary motor cortex, and extrastriate visual cortex. Much less is understood about the neural processes that underlie the immediate transition from low to high visual gain within a trial. This study used 128-channel electroencephalography to measure cortical activity during a visually guided precision grip task, in which the gain of the visual display was changed during the task. Force variability during the transition from low to high visual gain was characterized by an inverted U-shape, whereas force error decreased from low to high gain. Source analysis identified cortical activity in the same structures previously identified using functional magnetic resonance imaging. Source analysis also identified a time-varying shift in the strongest source activity. Superior regions of the motor and parietal cortex had stronger source activity from 300 to 600 ms after the transition, whereas inferior regions of the extrastriate visual cortex had stronger source activity from 500 to 700 ms after the transition. Force variability and electrical activity were linearly related, with a positive relation in the parietal cortex and a negative relation in the frontal cortex. Force error was nonlinearly related to electrical activity in the parietal cortex and frontal cortex by a quadratic function. This is the first evidence that force variability and force error are systematically related to a time-varying shift in cortical activity in frontal and parietal cortex in response to enhanced visual gain. PMID:23365186

Optical Spectroscopy Of Materials With Restricted Dimensions

NASA Astrophysics Data System (ADS)

Yen, William M...

1989-05-01

In this paper, we discuss various experimental advantages which are gained by using samples which have special dimensions and/or geometries. We limit our discussion here to the cylindrical geometry appropriate for optical fibers which are employed for various optoelectronic applications. We present results of laser spectroscopic studies of nominally pure and activated single crystal and glass fibers to illustrate some of these advantages. For example, we have succeeded for the first time in obtaining the dependence of the ruby R-lines and of the Raman spectra of sapphire on tensile stress. We further discuss a novel laser spectroscopic method, Dilution Narrowed Laser Spectroscopy or DNLS; we demonstrate this form of spectroscopy on single mode glass fibers activated with rare earth ions and consider the possibilities inherent in this technique.

Lifewide Learning for Early Reading Development.

PubMed

Dowd, Amy Jo; Friedlander, Elliott; Jonason, Christine; Leer, Jane; Sorensen, Lisa Zook; Guajardo, Jarrett; D'Sa, Nikhit; Pava, Clara; Pisani, Lauren

2017-03-01

The authors examine the relationships between children's reading abilities and the enabling environment for learning in the context of Save the Children's Literacy Boost program. They conceptualize the enabling environment at a micro level, with two components: the home literacy environment, represented by reading materials/habits at home, and the community learning environment (community reading activities). Using longitudinal reading scores of 6,874 students in 424 schools in 12 sites across Africa and Asia, there was 1) a modest but consistent relationship between students' home literacy environments and reading scores, and 2) a strong relationship between reading gains and participation in community reading activities, suggesting that interventions should consider both home and community learning environments and their differential influences on interventions across different low-resource settings. © 2017 Wiley Periodicals, Inc.

20 CFR 416.973 - General information about work activity.

Code of Federal Regulations, 2011 CFR

2011-04-01

... activity level. (b) How well you perform. We consider how well you do your work when we determine whether... that you are working at the substantial gainful activity level. If you are unable, because of your... gainful activity level. If you are doing work that involves minimal duties that make little or no demands...

20 CFR 220.142 - General information about work activity.

Code of Federal Regulations, 2011 CFR

2011-04-01

... substantial gainful activity level. If the claimant is unable, because of his or her impairments, to do... activity level. If the claimant is doing work that involves minimal duties that make little or no demands... claimant is working at the substantial gainful activity level. (c) If the claimant's work is done under...

20 CFR 220.142 - General information about work activity.

Code of Federal Regulations, 2012 CFR

2012-04-01

... business, this tends to show that the claimant has the ability to work at the substantial gainful activity... claimant has the necessary skills and ability to work at the substantial gainful activity level. (d) If the... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false General information about work activity. 220...

20 CFR 220.142 - General information about work activity.

Code of Federal Regulations, 2013 CFR

2013-04-01

... business, this tends to show that the claimant has the ability to work at the substantial gainful activity... claimant has the necessary skills and ability to work at the substantial gainful activity level. (d) If the... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true General information about work activity. 220...

20 CFR 220.142 - General information about work activity.

Code of Federal Regulations, 2014 CFR

2014-04-01

... business, this tends to show that the claimant has the ability to work at the substantial gainful activity... claimant has the necessary skills and ability to work at the substantial gainful activity level. (d) If the... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true General information about work activity. 220...

26 CFR 1.469-1 - General rules.

Code of Federal Regulations, 2011 CFR

2011-04-01

... sections 613A (d) and 1211. A passive activity deduction that is not disallowed for the taxable year under...): Example. In 1993, an individual derives $10,000 of ordinary income from passive activity X, no gains from... from passive activity Y, and no income, gain, deductions, or losses from any other passive activity...

Lasing in a single nanowire with quantum dots

NASA Astrophysics Data System (ADS)

Tatebayashi, Jun; Arakawa, Yasuhiko

2017-02-01

Nanowire (NW) lasers have recently attracted increasing attention as ultra-small, highly-efficient coherent light emitters in the fields of nanophotonics, nano-optics and nanobiotechnology. Although there have been several demonstrations of single NW lasers utilizing bulk materials, it is crucial to incorporate lower-dimensional quantum nanostructures into the NW in order to achieve superior device performance with respect to threshold current, differential gain, modulation bandwidth and temperature sensitivity. The quantum dot (QD) is a useful and essential nanostructure that can meet these requirements. In this presentation, we will talk about our recent research activity regarding room temperature lasing of a single GaAs NW containing 50-stacked In0.2Ga0.8As/GaAs QDs. The NW cavities consist of multiple In0.2Ga0.8As/GaAs heterostructures acting as a QD active material, which are grown on shallow (<45 nm) GaAs core NWs and followed by GaAs/Al0.1Ga0.9As/GaAs core/shell/cap structures. Lasing oscillation is achieved at the emission wavelength of 900 nm by properly designing the NW cavity and tailoring the emission energy of each QD to enhance the optical gain. Obtained threshold pump pulse fluence is 179 μJ/cm2 at room temperature and the characteristics temperature is 133K which is higher than that of conventional bulk NW lasers. Our demonstration paves the way toward ultra-small lasers with extremely low-power consumption for integrated photonic systems. Furthermore, we will discuss our recent results on the demonstration of several types of NWQD lasers in order to improve the device performance of the NWQD lasers.

Organization of the Optical Society of America Photonic Science Topical Meeting Series. Volume 14. Photorefractive Materials Effects, and Devices Held in Beverly, Massachusetts on 29-31 July 1991

DTIC Science & Technology

1991-01-01

STUDENT CENTER the photorefractive effect in cadmium sulfide. The maximum gain coefficient measured is 0.3 cm-1 at 633 nm. The r:00 am-8:00 am BREAKFAST...OK, 74354, Tel: 918-542 1801 00 00- 00 Abstract NWe report the first observation of the photorefractive effect in Cadmium sulfide. The maximum gain...the exception of GaP [1] none of these materials can be used in the wavelength range of 600-700 nm. Cadmium Sulfide (CdS) has been extensively

[The quality of the work-home and home-work relationship in the context of personal resources].

PubMed

Szymańska, Paulina

2014-01-01

The aim of the study was to examine whether gain or loss of personal resources is associated with conflict or facilitation between work and family. The study involved 90 employees (mean age: 34.5 years). The Polish version of COR-Evaluation (Conservation of Resources-Evaluation) questionnaire, developed by Hobfoll and adapted by Dudek et al, was used to assess personal resources. The questionnaire enables to estimate gain and loss of 40 resources and calculate the overall level of gained or lost resources. SWING Questionnaire (Survey Work-Home Interaction, Nijmegen), developed by Geurts et al. and adapted by Mośicka-Teske and Merecz), was used to examine the quality of work-home and home-work relationship. The gain of personal resources positively correlates with both home-work facilitation (HWF) and work-home facilitation (WHF). Improvement of the family relations proved to be the most significant predictor of HWF and WHF. The loss of personal resources coincides with high level of conflict between the investigated areas of life. The main predictor of home-work conflict (HWC) was the variable relating to restrictions of access to medical services. In case of work-home conflict (WHC) the reduction of material security in case of dramatic life events was the major predictor. The results confirmed that the gain of resources is crucial for HWF/WHF, while their loss is an important factor, when the HWC/WHC is considered. The resources, which proved to be the main predictors of work-home and home-work relatiohship were alsoindicated. The obtained information may be beneficial to human resources managers, especially in designing the activities aimed at increasing the satisfaction and effectiveness of employees.

Energy expenditure, spontaneous physical activity and with weight gain in kidney transplant recipients.

PubMed

Heng, Anne-Elisabeth; Montaurier, Christophe; Cano, Noël; Caillot, Nicolas; Blot, A; Meunier, Nathalie; Pereira, Bruno; Marceau, Geoffroy; Sapin, Vincent; Jouve, Christelle; Boirie, Yves; Deteix, Patrice; Morio, Beatrice

2015-06-01

Alterations in energy metabolism could trigger weight gain after renal transplantation. Nineteen transplanted non-diabetic men, 53 ± 1.6 years old, receiving calcineurin inhibitors but no corticosteroids were studied. They were compared with nine healthy men matched for height, age and lean body mass. Daily energy expenditure and its components (sleeping, basal and absorptive metabolic rates) were analyzed for 24 h in calorimetric chambers and for 4 days in free living conditions using calibrated accelerometry. Other variables known to influence energy expenditure were assessed: body composition, physical activity, 4-day food intake, drug consumption, serum C-reactive protein, interleukin-6, thyroid and parathyroid hormones, and epinephrine. Transplant recipients who gained more than 5% body weight after transplantation (n = 11, +11.0 ± 1.5 kg) were compared with those who did not (n = 8) and with the controls. Weight gain compared with non-weight gain patients and controls exhibited higher fat mass without change in lean body mass. Daily, sleeping and resting energy expenditure adjusted for lean body mass was significantly higher in non-weight gain (167.1 ± 4.2 kJ/kg/lean body mass/24 h, P < 0.05) compared with weight gain patients (147.4 ± 3.6) and controls (146.1 ± 4.6). Weight gain compared with controls and non-weight gain subjects had lower free living physical activity and a higher consumption of antihypertensive drugs and β-blockers. After kidney transplantation, weight gain patients were characterized by lower adjusted energy expenditure, reduced spontaneous physical activity but a more sedentary life style and a trend toward a higher energy intake explaining the reason they gained weight. The nWG KTR had increased resting and sleeping EE which protected them from weight gain. Such hypermetabolism was also observed in 24-h EE measurements. By comparison with the nWG patients, the WG transplant recipients were characterized by higher β-blocker consumption. These data could be helpful in the prevention of weight gain in kidney transplant recipients. Copyright © 2014. Published by Elsevier Ltd.

A full time-domain approach to spatio-temporal dynamics of semiconductor lasers. II. Spatio-temporal dynamics

NASA Astrophysics Data System (ADS)

Böhringer, Klaus; Hess, Ortwin

The spatio-temporal dynamics of novel semiconductor lasers is discussed on the basis of a space- and momentum-dependent full time-domain approach. To this means the space-, time-, and momentum-dependent Full-Time Domain Maxwell Semiconductor Bloch equations, derived and discussed in our preceding paper I [K. Böhringer, O. Hess, A full time-domain approach to spatio-temporal dynamics of semiconductor lasers. I. Theoretical formulation], are solved by direct numerical integration. Focussing on the device physics of novel semiconductor lasers that profit, in particular, from recent advances in nanoscience and nanotechnology, we discuss the examples of photonic band edge surface emitting lasers (PBE-SEL) and semiconductor disc lasers (SDLs). It is demonstrated that photonic crystal effects can be obtained for finite crystal structures, and leading to a significant improvement in laser performance such as reduced lasing thresholds. In SDLs, a modern device concept designed to increase the power output of surface-emitters in combination with near-diffraction-limited beam quality, we explore the complex interplay between the intracavity optical fields and the quantum well gain material in SDL structures. Our simulations reveal the dynamical balance between carrier generation due to pumping into high energy states, momentum relaxation of carriers, and stimulated recombination from states near the band edge. Our full time-domain approach is shown to also be an excellent framework for the modelling of the interaction of high-intensity femtosecond and picosecond pulses with semiconductor nanostructures. It is demonstrated that group velocity dispersion, dynamical gain saturation and fast self-phase modulation (SPM) are the main causes for the induced changes and asymmetries in the amplified pulse shape and spectrum of an ultrashort high-intensity pulse. We attest that the time constants of the intraband scattering processes are critical to gain recovery. Moreover, we present new insight into the physics of nonlinear coherent pulse propagation phenomena in active (semiconductor) gain media. Our numerical full time-domain simulations are shown to generally agree well with analytical predictions, while in the case of optical pulses with large pulse areas or few-cycle pulses they reveal the limits of analytic approaches. Finally, it is demonstrated that coherent ultrafast nonlinear propagation effects become less distinctive if we apply a realistic model of the quantum well semiconductor gain material, consider characteristic loss channels and take into account de-phasing processes and homogeneous broadening.

Effect of two different superstrate layers on bismuth titanate (BiT) array antennas.

PubMed

Wee, F H; Malek, F; Al-Amani, A U; Ghani, Farid

2014-01-15

The microwave industry has shown increasing interest in electronic ceramic material (ECM) due to its advantages, such as light weight, low cost, low loss, and high dielectric strength. In this paper, simple antennas covered by superstrate layers for 2.30 GHz to 2.50 GHz are proposed. The antennas are compact and have the capability of producing high performance in terms of gain, directivity, and radiation efficiency. Bismuth titanate with high dielectric constant of 21, was utilized as the ECM, while the superstrate layers chosen included a split ring resonator and dielectric material. The superstrate layers were designed for some improvement in the performance of directivity, gain, and return loss. The proposed antennas were simulated and fabricated. The results obtained were small antennas that possess high gain and high directivity with 360°, omni-directional signal transmission that resonant types of conventional dipole antenna cannot achieve. The gain of the antenna with the superstrate layer was enhanced by about 1 dBi over the antenna without a superstrate layer at 2.40 GHz.

Effect of Two Different Superstrate Layers On Bismuth Titanate (BiT) Array Antennas

NASA Astrophysics Data System (ADS)

Wee, F. H.; Malek, F.; Al-Amani, A. U.; Ghani, Farid

2014-01-01

The microwave industry has shown increasing interest in electronic ceramic material (ECM) due to its advantages, such as light weight, low cost, low loss, and high dielectric strength. In this paper, simple antennas covered by superstrate layers for 2.30 GHz to 2.50 GHz are proposed. The antennas are compact and have the capability of producing high performance in terms of gain, directivity, and radiation efficiency. Bismuth titanate with high dielectric constant of 21, was utilized as the ECM, while the superstrate layers chosen included a split ring resonator and dielectric material. The superstrate layers were designed for some improvement in the performance of directivity, gain, and return loss. The proposed antennas were simulated and fabricated. The results obtained were small antennas that possess high gain and high directivity with 360°, omni-directional signal transmission that resonant types of conventional dipole antenna cannot achieve. The gain of the antenna with the superstrate layer was enhanced by about 1 dBi over the antenna without a superstrate layer at 2.40 GHz.

Gain media edge treatment to suppress amplified spontaneous emission in a high power laser

DOEpatents

Hackel, Lloyd A [Livermore, CA; Soules, Thomas F [Livermore, CA; Fochs, Scott N [Livermore, CA; Rotter, Mark D [San Ramon, CA; Letts, Stephan A [San Ramon, CA

2011-02-22

A novel method and apparatus for suppressing ASE and/or parasitic oscillation modes in a laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges to a predetermined electromagnetic absorbing material arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE, parasitic oscillation modes and/or residual pump energy can be effectively suppressed.

Weight gain prevention in the school worksite setting: Results of a multi-level cluster randomized trial

PubMed Central

Lemon, Stephenie C.; Wang, Monica L.; Wedick, Nicole M.; Estabrook, Barbara; Druker, Susan; Schneider, Kristin L.; Li, Wenjun; Pbert, Lori

2014-01-01

Objective To describe the effectiveness, reach and implementation of a weight gain prevention intervention among public school employees. Method A multi-level intervention was tested in a cluster randomized trial among 782 employees in 12 central Massachusetts public high schools from 2009 to 2012. The intervention targeted the nutrition and physical activity environment and policies, the social environment and individual knowledge, attitudes and skills. The intervention was compared to a materials only condition. The primary outcome measures were change in weight and body mass index (BMI) at 24-month follow-up. Implementation of physical environment, policy and social environment strategies at the school and interpersonal levels, and intervention participation at the individual level were assessed. Results At 24-month follow-up, there was a net change (difference of the difference) of −3.03 pounds (p=.04) and of −.48 BMI units (p=.05) between intervention and comparison conditions. The majority of intervention strategies were successfully implemented by all intervention schools, although establishing formal policies was challenging. Employee participation in programs targeting the physical and social environment was maintained over time. Conclusion This study supports that a multi-level intervention integrated within the organizational culture can be successfully implemented and prevent weight gain in public high school employees. PMID:24345602

Low Loss Nanostructured Polymers for Chip-scale Waveguide Amplifiers.

PubMed

Chen, George F R; Zhao, Xinyu; Sun, Yang; He, Chaobin; Tan, Mei Chee; Tan, Dawn T H

2017-06-13

On-chip waveguide amplifiers offer higher gain in small device sizes and better integration with photonic devices than the commonly available fiber amplifiers. However, on-chip amplifiers have yet to make its way into the mainstream due to the limited availability of materials with ideal light guiding and amplification properties. A low-loss nanostructured on-chip channel polymeric waveguide amplifier was designed, characterized, fabricated and its gain experimentally measured at telecommunication wavelength. The active polymeric waveguide core comprises of NaYF 4 :Yb,Er,Ce core-shell nanocrystals dispersed within a SU8 polymer, where the nanoparticle interfacial characteristics were tailored using hydrolyzed polyhedral oligomeric silsesquioxane-graft-poly(methyl methacrylate) to improve particle dispersion. Both the enhanced IR emission intensity from our nanocrystals using a tri-dopant scheme and the reduced scattering losses from our excellent particle dispersion at a high solid loading of 6.0 vol% contributed to the outstanding optical performance of our polymeric waveguide. We achieved one of the highest reported gain of 6.6 dB/cm using a relatively low coupled pump power of 80 mW. These polymeric waveguide amplifiers offer greater promise for integrated optical circuits due to their processability and integration advantages which will play a key role in the emerging areas of flexible communication and optoelectronic devices.

High-velocity angular vestibulo-ocular reflex adaptation to position error signals.

PubMed

Scherer, Matthew; Schubert, Michael C

2010-06-01

Vestibular rehabilitation strategies including gaze stabilization exercises have been shown to increase gain of the angular vestibulo-ocular reflex (aVOR) using a retinal slip error signal (ES). The identification of additional ESs capable of promoting substitution strategies or aVOR adaptation is an important goal in the management of vestibular hypofunction. Position ESs have been shown to increase both aVOR gain and recruitment of compensatory saccades (CSs) during passive whole body rotation. This may be a useful compensatory strategy for gaze instability during active head rotation as well. In vestibular rehabilitation, the imaginary target exercise is often prescribed to improve gaze stability. This exercise uses a position ES; however, the mechanism for its effect has not been investigated. We compared aVOR gain adaptation using 2 types of small position ES: constant versus incremental. Ten subjects with normal vestibular function were assessed with unpredictable and active head rotations before and after a 20-minute training session. Subjects performed 9 epochs of 40 active, high-velocity head impulses using a position ES stimulus to increase aVOR gain. Five subjects demonstrated significant aVOR gain increases with the constant-position ES (mean, 2%; range, -18% to 12%) compared with another 5 subjects showing significant aVOR gain increases to the incremental-position ES (mean, 3.7%; range, -2% to 22.6%). There was no difference in aVOR gain adaptation or CS recruitment between the 2 paradigms. These findings suggest that some subjects can increase their aVOR gain in response to high-velocity active head movement training using a position ES. The primary mechanism for this seems to be aVOR gain adaptation because CS use was not modified. The overall low change in aVOR gain adaptation with position ES suggests that retinal slip is a more powerful aVOR gain modifier.

High-gain AlGaAs/GaAs double heterojunction Darlington phototransistors for optical neural networks

NASA Technical Reports Server (NTRS)

Kim, Jae H. (Inventor); Lin, Steven H. (Inventor)

1991-01-01

High-gain MOCVD-grown (metal-organic chemical vapor deposition) AlGaAs/GaAs/AlGaAs n-p-n double heterojunction bipolar transistors (DHBTs) and Darlington phototransistor pairs are provided for use in optical neural networks and other optoelectronic integrated circuit applications. The reduced base doping level used results in effective blockage of Zn out-diffusion, enabling a current gain of 500, higher than most previously reported values for Zn-diffused-base DHBTs. Darlington phototransitor pairs of this material can achieve a current gain of over 6000, which satisfies the gain requirement for optical neural network designs, which advantageously may employ neurons comprising the Darlington phototransistor pairs in series with a light source.

The Effectiveness of learning materials based on multiple intelligence on the understanding of global warming

NASA Astrophysics Data System (ADS)

Liliawati, W.; Purwanto; Zulfikar, A.; Kamal, R. N.

2018-05-01

This study aims to examine the effectiveness of the use of teaching materials based on multiple intelligences on the understanding of high school students’ material on the theme of global warming. The research method used is static-group pretest-posttest design. Participants of the study were 60 high school students of XI class in one of the high schools in Bandung. Participants were divided into two classes of 30 students each for the experimental class and control class. The experimental class uses compound-based teaching materials while the experimental class does not use a compound intelligence-based teaching material. The instrument used is a test of understanding of the concept of global warming with multiple choices form amounted to 15 questions and 5 essay items. The test is given before and after it is applied to both classes. Data analysis using N-gain and effect size. The results obtained that the N-gain for both classes is in the medium category and the effectiveness of the use of teaching materials based on the results of effect-size test results obtained in the high category.

Reducing the losses of optical metamaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Anan

The field of metamaterials is driven by fascinating and far-reaching theoretical visions, such as perfect lenses, invisibility cloaking, and enhanced optical nonlinearities. However, losses have become the major obstacle towards real world applications in the optical regime. Reducing the losses of optical metamaterials becomes necessary and extremely important. In this thesis, two approaches are taken to reduce the losses. One is to construct an indefinite medium. Indefinite media are materials where not all the principal components of the permittivity and permeability tensors have the same sign. They do not need the resonances to achieve negative permittivity, ε. So, the lossesmore » can be comparatively small. To obtain indefinite media, three-dimensional (3D) optical metallic nanowire media with different structures are designed. They are numerically demonstrated that they are homogeneous effective indefinite anisotropic media by showing that their dispersion relations are hyperbolic. Negative group refraction and pseudo focusing are observed. Another approach is to incorporate gain into metamaterial nanostructures. The nonlinearity of gain is included by a generic four-level atomic model. A computational scheme is presented, which allows for a self-consistent treatment of a dispersive metallic photonic metamaterial coupled to a gain material incorporated into the nanostructure using the finite-difference time-domain (FDTD) method. The loss compensations with gain are done for various structures, from 2D simplified models to 3D realistic structures. Results show the losses of optical metamaterials can be effectively compensated by gain. The effective gain coefficient of the combined system can be much larger than the bulk gain counterpart, due to the strong local-field enhancement.« less

Years of life gained due to leisure-time physical activity in the U.S.

PubMed

Janssen, Ian; Carson, Valerie; Lee, I-Min; Katzmarzyk, Peter T; Blair, Steven N

2013-01-01

Physical inactivity is an important modifiable risk factor for noncommunicable disease. The degree to which physical activity affects the life expectancy of Americans is unknown. This study estimated the potential years of life gained due to leisure-time physical activity in the U.S. Data from the National Health and Nutrition Examination Survey (2007-2010); National Health Interview Study mortality linkage (1990-2006); and U.S. Life Tables (2006) were used to estimate and compare life expectancy at each age of adult life for inactive (no moderate to vigorous physical activity); somewhat-active (some moderate to vigorous activity but <500 MET minutes/week); and active (≥ 500 MET minutes/week of moderate to vigorous activity) adults. Analyses were conducted in 2012. Somewhat-active and active non-Hispanic white men had a life expectancy at age 20 years that was ~2.4 years longer than that for the inactive men; this life expectancy advantage was 1.2 years at age 80 years. Similar observations were made in non-Hispanic white women, with a higher life expectancy within the active category of 3.0 years at age 20 years and 1.6 years at age 80 years. In non-Hispanic black women, as many as 5.5 potential years of life were gained due to physical activity. Significant increases in longevity were also observed within somewhat-active and active non-Hispanic black men; however, among Hispanics the years-of-life-gained estimates were not significantly different from 0 years gained. Leisure-time physical activity is associated with increases in longevity. Copyright © 2013 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

Years of Life Gained Due to Leisure-Time Physical Activity in the United States

PubMed Central

Janssen, Ian; Carson, Valerie; Lee, I-Min; Katzmarzyk, Peter T.; Blair, Steven N.

2013-01-01

Background Physical inactivity is an important modifiable risk factor for non-communicable disease. The degree to which physical activity affects the life expectancy of Americans is unknown. This study estimated the potential years of life gained due to leisure-time physical activity across the adult lifespan in the United States. Methods Data from the National Health and Nutrition Examination Survey (2007–2010), National Health Interview Study mortality linkage (1990–2006), and US Life Tables (2006) were used to estimate and compare life expectancy at each age of adult life for inactive (no moderate-to-vigorous physical activity), somewhat active (some moderate-to-vigorous activity but <500 metabolic equivalent min/week) and active (≥500 metabolic equivalent min/week of moderate-to-vigorous activity) adults. Analyses were conducted in 2012. Results Somewhat active and active non-Hispanic white men had a life expectancy at age 20 that was around 2.4 years longer than the inactive men; this life expectancy advantage was 1.2 years at age 80. Similar observations were made in non-Hispanic white women, with a higher life expectancy within the active category of 3.0 years at age 20 and 1.6 years at age 80. In non-Hispanic black women, as many as 5.5 potential years of life were gained due to physical activity. Significant increases in longevity were also observed within somewhat active and active non-Hispanic black men; however, among Hispanics the years of life gained estimates were more variable and not significantly different from 0 years gained. Conclusions Leisure-time physical activity is associated with increases in longevity in the United States. PMID:23253646

Doping-Induced Interband Gain in InAs/AlSb Quantum Wells

NASA Technical Reports Server (NTRS)

Kolokolov, K. I.; Ning, C. Z.

2005-01-01

A paper describes a computational study of effects of doping in a quantum well (QW) comprising a 10-nm-thick layer of InAs sandwiched between two 21-nm-thick AlSb layers. Heretofore, InAs/AlSb QWs have not been useful as interband gain devices because they have type-II energy-band-edge alignment, which causes spatial separation of electrons and holes, thereby leading to weak interband dipole matrix elements. In the doping schemes studied, an interior sublayer of each AlSb layer was doped at various total areal densities up to 5 X 10(exp 12) / square cm. It was found that (1) proper doping converts the InAs layer from a barrier to a well for holes, thereby converting the heterostructure from type II to type I; (2) the resultant dipole matrix elements and interband gains are comparable to those of typical type-I heterostructures; and (3) dipole moments and optical gain increase with the doping level. Optical gains in the transverse magnetic mode can be almost ten times those of other semiconductor material systems in devices used to generate medium-wavelength infrared (MWIR) radiation. Hence, doped InAs/AlSb QWs could be the basis of an alternative material system for devices to generate MWIR radiation.

An amorphous silicon photodiode with 2 THz gain-bandwidth product based on cycling excitation process

NASA Astrophysics Data System (ADS)

Yan, Lujiang; Yu, Yugang; Zhang, Alex Ce; Hall, David; Niaz, Iftikhar Ahmad; Raihan Miah, Mohammad Abu; Liu, Yu-Hsin; Lo, Yu-Hwa

2017-09-01

Since impact ionization was observed in semiconductors over half a century ago, avalanche photodiodes (APDs) using impact ionization in a fashion of chain reaction have been the most sensitive semiconductor photodetectors. However, APDs have relatively high excess noise, a limited gain-bandwidth product, and high operation voltage, presenting a need for alternative signal amplification mechanisms of superior properties. As an amplification mechanism, the cycling excitation process (CEP) was recently reported in a silicon p-n junction with subtle control and balance of the impurity levels and profiles. Realizing that CEP effect depends on Auger excitation involving localized states, we made the counter intuitive hypothesis that disordered materials, such as amorphous silicon, with their abundant localized states, can produce strong CEP effects with high gain and speed at low noise, despite their extremely low mobility and large number of defects. Here, we demonstrate an amorphous silicon low noise photodiode with gain-bandwidth product of over 2 THz, based on a very simple structure. This work will impact a wide range of applications involving optical detection because amorphous silicon, as the primary gain medium, is a low-cost, easy-to-process material that can be formed on many kinds of rigid or flexible substrates.

Long term monitoring of mechanical properties of FRP repair materials.

DOT National Transportation Integrated Search

2013-06-01

Over the years, Fiber Reinforced Polymer (FRP) composites have gained popularity in transportation infrastructure as a material able to restore and increase the capacity of existing concrete elements. Properties such as a high strength to weight rati...

Investigating message-framing effects in the context of a tailored intervention promoting physical activity.

PubMed

van 't Riet, Jonathan; Ruiter, Robert A C; Werrij, Marieke Q; de Vries, Hein

2010-04-01

Health-promoting messages can be framed in terms of the gains associated with healthy behaviour or the losses associated with unhealthy behaviour. It has been argued that gain-framed messages promoting physical activity (PA) are more effective than loss-framed messages, but empirical findings are inconsistent. Also, no previous studies investigated the effects of gain- and loss-framed messages in the context of a computer-tailored PA intervention. In this study, we provided participants with computer-generated tailored feedback concerning their PA levels. In total, 787 participants entered in the study, of whom 299 completed all measures at a 3-month follow-up. We investigated whether gain- and loss-framed messages promoting PA affected information acceptance, attitude, intention and behaviour differently. The results showed that gain-framed messages resulted in stronger intentions to be physically active than loss-framed messages. This did not result in a significant increase in actual PA, however, as measured by a 3-month follow-up assessment. For information acceptance and attitude, a non-significant advantage of gain-framed messages was found. All effects had small effect sizes. Thus, whereas gain-framed information might be more persuasive than loss-framed information when it comes to promoting PA, the differences between gain- and loss-framed messages are likely to be small.

20 CFR 220.29 - Work that is considered substantial gainful activity.

Code of Federal Regulations, 2013 CFR

2013-04-01

... RAILROAD RETIREMENT ACT DETERMINING DISABILITY Disability Under the Railroad Retirement Act for Any Regular Employment § 220.29 Work that is considered substantial gainful activity. Work is considered to be...

Titanium Mass-balance Analysis of Paso Robles Soils: Elemental Gains and Losses as Affected by Acid Alteration Fluids

NASA Technical Reports Server (NTRS)

Sutter, Brad; Ming, Douglas W.

2010-01-01

The Columbia Hills soils have been exposed to aqueous alteration in alkaline [1] as well as acid conditions [2,3]. The Paso Robles class soils are bright soils that possess the highest S concentration of any soil measured on Mars [2]. Ferric-sulfate detection by Moessbauer analysis indicated that acid solutions were involved in forming these soils [4]. These soils are proposed to have formed by alteration of nearby rock by volcanic hydrothermal or fumarolic activity. The Paso Robles soils consist of the original Paso Robles-disturbed-Pasadena (PR-dist), Paso Robles- PasoLight (PR-PL), Arad-Samra, Arad-Hula, Tyrone- Berker Island1 and Tyrone-MountDarwin [2 ,3. ]Chemical characteristics indicate that the PR-dist and PR-PL soils could be derived from acid weathering of local Wishstone rocks while the Samra and Hula soils are likely derived from local Algonquin-Iroquet rock [3]. The Paso Robles soils were exposed to acidic sulfur bearing fluids; however, little else is known about the chemistry of the alteration fluid and its effects on the alteration of the proposed parent materials. The objectives of this work are to conduct titanium normalized mass-balance analysis to1) assess elemental gains and losses from the parent materials in the formation of the Paso Robles soils and 2) utilize this information to indicate the chemical nature of the alteration fluids.

20 CFR 404.325 - The termination month.

Code of Federal Regulations, 2011 CFR

2011-04-01

... activity level and continue to do so throughout the 36 months following completion of your trial work... third month following the earliest month you perform substantial gainful activity or are determined able to perform substantial gainful activity; however, in no event will the termination month under these...

20 CFR 404.325 - The termination month.

Code of Federal Regulations, 2010 CFR

2010-04-01

... activity level and continue to do so throughout the 36 months following completion of your trial work... third month following the earliest month you perform substantial gainful activity or are determined able to perform substantial gainful activity; however, in no event will the termination month under these...

Maintaining vigorous activity attenuates 7-yr weight gain in 8340 runners.

PubMed

Williams, Paul T

2007-05-01

Body weight generally increases with aging in Western societies. Although training studies show that exercise produces acute weight loss, it is unclear whether the long-term maintenance of vigorous exercise attenuates the trajectory of age-related weight gain. Specifically, prior studies have not tested whether the maintenance of physical activity, in the absence of any change in activity, prevents weight gain. Prospective study of 6119 male and 2221 female runners whose running distances changed < 5 km x wk(-1) between baseline and follow-up surveys 7 yr later. On average, men who maintained modest (0-23 km x wk(-1)), intermediate (24-47 km x wk(-1)), or prolonged running distances (> or = 48 km x wk(-1)) all gained weight through age 64; however, those who maintained > or = 48 km x wk(-1) had one half the average annual weight gain of those who maintained < 24 km x wk(-1). For example, between the ages of 35 and 44 in men and 30 and 39 yr in women, those who maintained < 24 km x wk(-1) gained, on average, 2.1 and 2.9 kg more per decade than those averaging > 48 km x wk(-1). Age-related weight gain, and its attenuation by maintained exercise, were both greater in younger than in older men. Men's gains in waist circumference with age, and its attenuation by maintaining running, were the same in older and younger men. Regardless of age, women increased their body weight, waist circumference, and hip circumference over time, and these measurements were attenuated in proportion to their maintained running distance. In both sexes, running disproportionately prevented more extreme increases in weight. As they aged, men and women gained less weight in proportion to their levels of sustained vigorous activity. This long-term beneficial effect is in addition to the acute weight loss that occurs with increased activity.

Gain and losses in THz quantum cascade laser with metal-metal waveguide.

PubMed

Martl, Michael; Darmo, Juraj; Deutsch, Christoph; Brandstetter, Martin; Andrews, Aaron Maxwell; Klang, Pavel; Strasser, Gottfried; Unterrainer, Karl

2011-01-17

Coupling of broadband terahertz pulses into metal-metal terahertz quantum cascade lasers is presented. Mode matched terahertz transients are generated on the quantum cascade laser facet of subwavelength dimension. This method provides a full overlap of optical mode and active laser medium. A longitudinal optical-phonon depletion based active region design is investigated in a coupled cavity configuration. Modulation experiments reveal spectral gain and (broadband) losses. The observed gain shows high dynamic behavior when switching from loss to gain around threshold and is clamped at total laser losses.

Preterm Infant Weight Gain is Increased by Massage Therapy and Exercise Via Different Underlying Mechanisms

PubMed Central

Diego, Miguel A.; Field, Tiffany; Hernandez-Reif, Maria

2014-01-01

Objective To compare the effects of massage therapy (moderate pressure stroking) and exercise (flexion and extension of limbs) on preterm infants’ weight gain and to explore potential underlying mechanisms for those effects. Methods Weight gain and parasympathetic nervous system activity were assessed in 30 preterm infants randomly assigned to a massage therapy group or to an exercise group. Infants received 10 minutes of moderate pressure massage or passive flexion and extension of the limbs 3 times per day for 5 days, and EKGs were collected during the first session to assess vagal activity. Results Both massage and exercise led to increased weight gain. However, while exercise was associated with increased calorie consumption, massage was related to increased vagal activity. Conclusion Taken together, these findings suggest that massage and exercise lead to increased preterm infant weight gain via different underlying mechanisms. PMID:24480603

Variable gain for a wind turbine pitch control

NASA Technical Reports Server (NTRS)

Seidel, R. C.; Birchenough, A. G.

1981-01-01

The gain variation is made in the software logic of the pitch angle controller. The gain level is changed depending upon the level of power error. The control uses low gain for low pitch activity the majority of the time. If the power exceeds ten percent offset above rated, the gain is increased to a higher gain to more effectively limit power. A variable gain control functioned well in tests on the Mod-0 wind turbine.

26 CFR 7.105-1 - Questions and answers relating to exclusions of certain disability income payments.

Code of Federal Regulations, 2011 CFR

2011-04-01

... engage in any substantial gainful activity by reason of any medically determinable physical or mental... exemption for age and the credit for the elderly? A-9: No. For purposes of the disability income exclusion... substantial gainful activity referred to is not limited to the activity, or a comparable activity, in which...

Environmentally-Friendly Geopolymeric Binders Made with Silica

NASA Astrophysics Data System (ADS)

Erdogan, S. T.

2013-12-01

Portland cement (PC) is the ubiquitous binding material for constructions works. It is a big contributor to global warming and climate change since its production is responsible for 5-10 % of all anthropogenic CO2 emissions. Half of this emission arises from the calcination of calcareous raw materials and half from kiln fuel burning and cement clinker grinding. Recently there have been efforts to develop alternative binders with lower greenhouse gas emissions. One such class of binders is geopolymers, formed by activating natural or waste materials with suitable alkaline or acidic solutions. These binders use natural or industrial waste raw materials with a very low CO2 footprint from grinding of the starting materials, and some from the production of the activating chemicals. The total CO2 emissions from carefully formulated mixtures can be as low as 1/10th - 1/5th of those of PC concrete mixtures with comparable properties. While use of industrial wastes as raw materials is environmentally preferable, the variability of their chemical compositions over time renders their use difficult. Use of natural materials depletes resources but can have more consistent properties and can be more easily accepted. Silica sand is a natural material containing very high amounts of quartz. Silica fume is a very fine waste from silicon metal production that is mostly non-crystalline silica. This study describes the use of sodium hydroxide and sodium silicate solutions to yield mortars with mechanical properties comparable to those of portland cement mortars and with better chemical and thermal durability. Strength gain is slower than with PC mixtures at room temperature but adequate ultimate strength can be achieved with curing at slightly elevated temperatures in less than 24 h. The consistency of the chemical compositions of these materials and their abundance in several large, developing countries makes silica attractive for producing sustainable concretes with reduced carbon footprints.

An efficient fast response and high-gain solar-blind flexible ultraviolet photodetector employing hybrid geometry

NASA Astrophysics Data System (ADS)

Hussain, Amreen A.; Pal, Arup R.; Patil, Dinkar S.

2014-05-01

We report high performance flexible hybrid ultraviolet photodetector with solar-blind sensitivity using nanocomposite film of plasma polymerized aniline-titanium dioxide. A facile solvent-free plasma technique is used to synthesize superior quality hybrid material with high yield. The hybrid photodetector exhibited high photoconductive gain of the order of ˜105 and fast speed with response and recovery time of 22.87 ms and 34.23 ms. This is an excellent result towards getting a balance in the response speed and photoconductive gain trade-off of the photodetectors reported so far. In addition, the device has the advantages of enhanced photosensitivity ((Ilight - Idark)/Idark) of the order of ˜102 and high responsivity of ˜104 AW-1. All the merits substantiates that, to prepare hybrid material, plasma based method holds potential to be an easy way for realizing large scale nanostructured photodetectors for practical applications.

Relative Influence of Socioeconomic, Psychological and Sensory Characteristics, Physical Activity and Diet on 5-Year Weight Gain in French Adults

PubMed Central

Castetbon, Katia; Hanafi, Mohamed; Deglaire, Amélie; Schlich, Pascal; Péneau, Sandrine; Méjean, Caroline

2017-01-01

Individual characteristics, dietary intake and physical activity influence weight status; however, the contribution of each factor to weight change has not been studied. The objective was to confirm a conceptual framework by simultaneously assessing the relative influence of socioeconomic, psychological and sensory characteristics, physical activity, and dietary intake on five-year weight gain in French adults. Individual characteristics, physical activity, and dietary data were assessed at baseline in 8014 participants in the NutriNet-Santé cohort. Self-reported anthropometric data were collected at baseline and five years later. Structural equation models, stratified by baseline body mass index (BMI), were used to perform analyses. Dietary restraint was a direct predictor of weight gain, with a stronger effect than age or intake of energy-dense foods, both in non-overweight and overweight participants. In non-overweight individuals only, intake of nutrient-dense foods and physical activity were inversely associated with weight gain. Regarding dietary intake, fat liking was the most important predictor of nutrient-dense food intake and was also related to energy-dense food intake. In these models, dietary restraint appears to be a direct predictor of weight gain and fat liking is a strong determinant of dietary intake. The influence of dietary restraint on weight gain, not explained by diet, warrants further investigation. PMID:29143765

Effect of conduction band non-parabolicity on the optical gain of quantum cascade lasers based on the effective two-band finite difference method

NASA Astrophysics Data System (ADS)

Cho, Gookbin; Kim, Jungho

2017-09-01

We theoretically investigate the effect of conduction band non-parabolicity (NPB) on the optical gain spectrum of quantum cascade lasers (QCLs) using the effective two-band finite difference method. Based on the effective two-band model to consider the NPB effect in the multiple quantum wells (QWs), the wave functions and confined energies of electron states are calculated in two different active-region structures, which correspond to three-QW single-phonon and four-QW double-phonon resonance designs. In addition, intersubband optical dipole moments and polar-optical-phonon scattering times are calculated and compared without and with the conduction band NPB effect. Finally, the calculation results of optical gain spectra are compared in the two QCL structures having the same peak gain wavelength of 8.55 μm. The gain peaks are greatly shifted to longer wavelengths and the overall gain magnitudes are slightly reduced when the NPB effect is considered. Compared with the three-QW active-region design, the redshift of the peak gain is more prominent in the four-QW active-region design, which makes use of higher electronic states for the lasing transition.

Static aeroelastic behavior of an adaptive laminated piezoelectric composite wing

NASA Technical Reports Server (NTRS)

Weisshaar, T. A.; Ehlers, S. M.

1990-01-01

The effect of using an adaptive material to modify the static aeroelastic behavior of a uniform wing is examined. The wing structure is idealized as a laminated sandwich structure with piezoelectric layers in the upper and lower skins. A feedback system that senses the wing root loads applies a constant electric field to the piezoelectric actuator. Modification of pure torsional deformaton behavior and pure bending deformation are investigated, as is the case of an anisotropic composite swept wing. The use of piezoelectric actuators to create an adaptive structure is found to alter static aeroelastic behavior in that the proper choice of the feedback gain can increase or decrease the aeroelastic divergence speed. This concept also may be used to actively change the lift effectiveness of a wing. The ability to modify static aeroelastic behavior is limited by physical limitations of the piezoelectric material and the manner in which it is integrated into the parent structure.

The Next Breakthrough for Organic Photovoltaics?

PubMed

Jackson, Nicholas E; Savoie, Brett M; Marks, Tobin J; Chen, Lin X; Ratner, Mark A

2015-01-02

While the intense focus on energy level tuning in organic photovoltaic materials has afforded large gains in device performance, we argue here that strategies based on microstructural/morphological control are at least as promising in any rational design strategy. In this work, a meta-analysis of ∼150 bulk heterojunction devices fabricated with different materials combinations is performed and reveals strong correlations between power conversion efficiency and morphology-dominated properties (short-circuit current, fill factor) and surprisingly weak correlations between efficiency and energy level positioning (open-circuit voltage, enthalpic offset at the interface, optical gap). While energy level positioning should in principle provide the theoretical maximum efficiency, the optimization landscape that must be navigated to reach this maximum is unforgiving. Thus, research aimed at developing understanding-based strategies for more efficient optimization of an active layer microstructure and morphology are likely to be at least as fruitful.

Antimicrobial properties of graphene-like nanoparticles: coating effect on Staphylococcus aureus

NASA Astrophysics Data System (ADS)

Olivi, M.; Alfè, M.; Gargiulo, V.; Valle, F.; Mura, F.; Di Giosia, M.; Rapino, S.; Palleschi, C.; Uccelletti, D.; Fiorito, S.

2016-12-01

The exploitation of nanomaterials with antimicrobial properties has attracted an ever-growing interest in the recent years. Carbon-based materials, such as graphene and graphene family materials (GFMs), have gained most of the attention for application in many biomedical fields. Here, we describe the antimicrobial activity of graphene-like (GL) layers derived from the chemical demolition of carbon black, against the planktonic growth of Staphylococcus aureus cells, primary cause of hospital and community-acquired infections, often leading to bacteremia and sepsis. The inhibitory capabilities of GL layers on the formation of S. aureus biofilm are also assessed. The antimicrobial properties seem based mainly on the interaction between GL layers and bacteria surfaces. FESEM and AFM analyses suggest that the GL layers coat the cells as soon as they get in contact with them, as also indicated by the wettability of the GLs.

Detailed investigation of Na2.24FePO4CO3 as a cathode material for Na-ion batteries

PubMed Central

Huang, Weifeng; Zhou, Jing; Li, Biao; Ma, Jin; Tao, Shi; Xia, Dingguo; Chu, Wangsheng; Wu, Ziyu

2014-01-01

Na-ion batteries are gaining an increased recognition as the next generation low cost energy storage devices. Here, we present a characterization of Na3FePO4CO3 nanoplates as a novel cathode material for sodium ion batteries. First-principles calculations reveal that there are two paths for Na ion migration along b and c axis. In-situ and ex-situ Fe K-edge X-ray absorption near edge structure (XANES) point out that in Na3FePO4CO3 both Fe2+/Fe3+ and Fe3+/Fe4+ redox couples are electrochemically active, suggesting also the existence of a two-electron intercalation reaction. Ex-situ X-ray powder diffraction data demonstrates that the crystalline structure of Na3FePO4CO3 remains stable during the charging/discharging process within the range 2.0–4.55 V. PMID:24595232

Switching of the direction of reflectionless light propagation at exceptional points in non-PT-symmetric structures using phase-change materials.

PubMed

Huang, Yin; Shen, Yuecheng; Min, Changjun; Veronis, Georgios

2017-10-30

We introduce a non-parity-time-symmetric three-layer structure, consisting of a gain medium layer sandwiched between two phase-change medium layers for switching of the direction of reflectionless light propagation. We show that for this structure unidirectional reflectionlessness in the forward direction can be switched to unidirectional reflectionlessness in the backward direction at the optical communication wavelength by switching the phase-change material Ge 2 Sb 2 Te 5 (GST) from its amorphous to its crystalline phase. We also show that it is the existence of exceptional points for this structure with GST in both its amorphous and crystalline phases which leads to unidirectional reflectionless propagation in the forward direction for GST in its amorphous phase, and in the backward direction for GST in its crystalline phase. Our results could be potentially important for developing a new generation of compact active free-space optical devices.

Thermo-Optical and Mechanical Property Testing of Candidate Solar Sail Materials

NASA Technical Reports Server (NTRS)

Hollerman, WIlliam A.; Stanaland, T. L.; Womack, F.; Edwards, David; Hubbs, Whitney; Semmel, Charles

2003-01-01

Solar sailing is a unique form of propulsion where a spacecraft gains momentum from incident photons. Since sails are not limited by reaction mass, they provide continual acceleration, reduced only by the lifetime of the lightweight film in the space environment and the distance to the Sun. Practical solar sails can expand the number of possible missions, enabling new concepts that are difficult by conventional means. The National Aeronautics and Space Administration's Marshall Space Flight Center (MSFC) is concentrating research into the utilization of ultra-lightweight materials for spacecraft propulsion. Solar sails are generally composed of a highly reflective metallic front layer, a thin polymeric substrate, and occasionally a highly emissive back surface. The Space Environmental Effects Team at MSFC is actively characterizing candidate sails to evaluate the thermo-optical and mechanical properties after exposure to electrons. This poster will discuss the preliminary results of this research.

Nanocellulose-based composites and bioactive agents for food packaging.

PubMed

Khan, Avik; Huq, Tanzina; Khan, Ruhul A; Riedl, Bernard; Lacroix, Monique

2014-01-01

Global environmental concern, regarding the use of petroleum-based packaging materials, is encouraging researchers and industries in the search for packaging materials from natural biopolymers. Bioactive packaging is gaining more and more interest not only due to its environment friendly nature but also due to its potential to improve food quality and safety during packaging. Some of the shortcomings of biopolymers, such as weak mechanical and barrier properties can be significantly enhanced by the use of nanomaterials such as nanocellulose (NC). The use of NC can extend the food shelf life and can also improve the food quality as they can serve as carriers of some active substances, such as antioxidants and antimicrobials. The NC fiber-based composites have great potential in the preparation of cheap, lightweight, and very strong nanocomposites for food packaging. This review highlights the potential use and application of NC fiber-based nanocomposites and also the incorporation of bioactive agents in food packaging.

Final project report for NEET pulsed ion beam project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kucheyev, S. O.

The major goal of this project was to develop and demonstrate a novel experimental approach to access the dynamic regime of radiation damage formation in nuclear materials. In particular, the project exploited a pulsed-ion-beam method in order to gain insight into defect interaction dynamics by measuring effective defect interaction time constants and defect diffusion lengths. This project had the following four major objectives: (i) the demonstration of the pulsed ion beam method for a prototypical nuclear ceramic material, SiC; (ii) the evaluation of the robustness of the pulsed beam method from studies of defect generation rate effects; (iii) the measurementmore » of the temperature dependence of defect dynamics and thermally activated defect-interaction processes by pulsed ion beam techniques; and (iv) the demonstration of alternative characterization techniques to study defect dynamics. As we describe below, all these objectives have been met.« less

Analysis of a Constellation Lab Cooperative Learning Activity

NASA Astrophysics Data System (ADS)

Gauthier, A. J.

2001-12-01

A cooperative learning activity was designed for use in the undergraduate laboratory course Introduction to Astronomical Observation. This group exercise enhances the student's learning of constellations and will hopefully increase retention of the material throughout the semester. It also serves as an "ice-breaker" during the first week of lab, promoting student involvement and vested interest in the course. To gain some insight into the student mind, a survey was conducted to evaluate the usefulness and overall opinion of this method. The students who completed the survey had previously been enrolled in a pre-requisite astronomy course that also required a constellation lab. In this previous course they "learned" the constellations from an instructor and a flashlight beam, studied them on their own, and then promptly took a quiz. Both methods are analyzed from an instructional designer's point of view and suggestions for future activities are presented. The preliminary results and accompanying activity will be discussed in poster and hand-out medium.

Synthesis and evaluation of anticonvulsant activities of some new arylhexahydropyrimidine-2,4-diones.

PubMed

Caliş, U; Köksal, M

2001-01-01

In this study, some new 3-alkyl-6-arylhexahydropyrimidine-2,4-dione derivatives were synthesized as anticonvulsant agents. 6-Arylhexahydropyrimidine-2,4-diones which were used as starting materials in the synthesis of the compounds were prepared in acidic media by the cyclization of potassium cyanate and the appropriate ureido acids that were gained by the reaction of beta-aminoacids, malonic acid and ammonium acetate. The structures of the synthesized compounds were confirmed by UV, IR, 1H-NMR and elementary analysis. Their anticonvulsant activities were determined by maximal electroshock (MES), subcutaneous metrazol (scMet) and rotorod toxicity tests for neurological deficits. According to the activity studies, 3-arylalkyl-6-(p-chlorophenyl) derivatives were found to be protective against scMet, whereas 6-phenyl derivatives were not. 6-Phenyl-3-(2-morpholinoethyl)hexahydropyrimidine-2,4-dione was the only compound determined to be active against MES at 300 mg/kg dose at half an hour.

A study to compare traditional and constructivism-based instruction of a high school biology unit on biosystematics

NASA Astrophysics Data System (ADS)

Saigo, Barbara Woodworth

The researcher collaborated with four high school biology teachers who had been involved for 2-1/2 years in a constructivism-based professional development experience that emphasized teaching for conceptual change and using classroom-based inquiry as a basis for making instructional decisions. The researcher and teachers designed a five-day instructional unit on biosystematics using two contrasting approaches, comprising the treatment variable. The "traditional" unit emphasized lecture, written materials, and some laboratory activities. The "constructivist" unit emphasized a specific, inquiry-based, conceptual change strategy and collaborative learning. The study used a quasi-experimental, factorial design to explore impact of instructional approach (the treatment variable) on student performance (the dependent variable) on repeated measures (three) of a biology concept test. Additional independent variables considered were gender, cumulative GPA, and the section in which students were enrolled. Scores on the biology concept test were compiled for the 3 constructivist sections (N = 44) and the 3 traditional sections (N = 42). Analysis of Covariance (ANCOVA) was applied. The main findings in regard to the primary research question were that instructional approach did not have a significant relationship to immediate post test scores or gain, but that one month after instruction students in the constructivist group demonstrated less loss of gain than those in the traditional group; i.e., their longer-term retention was greater. Also, GPA*instructional approach effects were detected for post-post-test gain. GPA and gender were significantly associated with pre-test, post-test, and post-post scores; however, in terms of change (gain) from pre-test to post-test and pre-test to post-post-test, GPA and gender were not significant effects. Section was a significant effect for all three tests, in terms of both score and gain. Gender*section effects were detected for post-test gain and post-post-test scores.

Gain and Bandwidth Enhancement of Ferrite-Loaded CBS Antenna Using Material Shaping and Positioning

NASA Astrophysics Data System (ADS)

Askarian Amiri, Mikal

Loading a cavity-backed slot (CBS) antenna with ferrite material and applying a biasing static magnetic field can be used to control its resonant frequency. Such a mechanism results in a frequency reconfigurable antenna. However, placing a lossy ferrite material inside the cavity can reduce the gain or negatively impact the impedance bandwidth. This thesis develops guidelines, based on a non-uniform applied magnetic field and non-uniform magnetic field internal to the ferrite specimen, for the design of ferrite-loaded CBS antennas which enhance their gain and tunable bandwidth by shaping the ferrite specimen and judiciously locating it within the cavity. To achieve these objectives, it is necessary to examine the influence of the shape and relative location of the ferrite material, and also the proximity of the ferrite specimen from the probe on the DC magnetic field and RF electric field distributions inside the cavity. The geometry of the probe and its impacts on figures-of-merit of the antenna is of interest as well. Two common cavity backed-slot antennas (rectangular and circular cross-section) were designed, and corresponding simulations and measurements were performed and compared. The cavities were mounted on 30 cm × 30 cm perfect electric conductor (PEC) ground planes and partially loaded with ferrite material. The ferrites were biased with an external magnetic field produced by either an electromagnet or permanent magnets. Simulations were performed using FEM-based commercial software, Ansys' Maxwell 3D and HFSS. Maxwell 3D is utilized to model the non-uniform DC applied magnetic field and non-uniform magnetic field internal to the ferrite specimen; HFSS however, is used to simulate and obtain the RF characteristics of the antenna. To validate the simulations they were compared with measurements performed in ASU's EM Anechoic Chamber. After many examinations using simulations and measurements, some optimal designs guidelines with respect to the gain, return loss and tunable impedance bandwidth, were obtained and recommended for ferrite-loaded CBS antennas.

20 CFR 220.145 - Impairment-related work expenses.

Code of Federal Regulations, 2014 CFR

2014-04-01

... ACT DETERMINING DISABILITY Substantial Gainful Activity § 220.145 Impairment-related work expenses. (a... gainful activity, the Board will subtract the reasonable costs to the claimant of certain items and... adverse impact on the claimant's ability to function in his or her work activity. In this situation, the...

20 CFR 220.145 - Impairment-related work expenses.

Code of Federal Regulations, 2011 CFR

2011-04-01

... ACT DETERMINING DISABILITY Substantial Gainful Activity § 220.145 Impairment-related work expenses. (a... gainful activity, the Board will subtract the reasonable costs to the claimant of certain items and... adverse impact on the claimant's ability to function in his or her work activity. In this situation, the...

20 CFR 220.145 - Impairment-related work expenses.

Code of Federal Regulations, 2013 CFR

2013-04-01

... ACT DETERMINING DISABILITY Substantial Gainful Activity § 220.145 Impairment-related work expenses. (a... gainful activity, the Board will subtract the reasonable costs to the claimant of certain items and... adverse impact on the claimant's ability to function in his or her work activity. In this situation, the...

20 CFR 220.145 - Impairment-related work expenses.

Code of Federal Regulations, 2012 CFR

2012-04-01

... ACT DETERMINING DISABILITY Substantial Gainful Activity § 220.145 Impairment-related work expenses. (a... gainful activity, the Board will subtract the reasonable costs to the claimant of certain items and... adverse impact on the claimant's ability to function in his or her work activity. In this situation, the...

Dependence of astigmatism, far-field pattern, and spectral envelope width on active layer thickness of gain guided lasers with narrow stripe geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mamine, T.

1984-06-15

The effects of active layer thickness on the astigmatism, the angle of far-field pattern width parallel to the junction, and the spectral envelope width of a gain guided laser with a narrow stripe geometry have been investigated analytically and experimentally. It is concluded that a large level of astigmatism, a narrow far-field pattern width, and a rapid convergence of the spectral envelope width are inherent to the gain guided lasers with thin active layers.

Hershberger Assays for Di-2-ethylhexyl Phthalate and Its Substitute Candidates

PubMed Central

Kim, Hee-Su; Cheon, Yong-Pil; Lee, Sung-Ho

2018-01-01

ABSTRACT In the present study, we employed Hershberger assay to determine possible androgenic or antiandrogenic activities of three di-2-ethylhexyl phthalate (DEHP) substitute candidates. The assay was carried out using immature castrated Sprague–Dawley male rats. After 7 days of the surgery, testosterone propionate (TP, 0.4 mg/kg/day) and test materials (low dose, 40 mg/kg/day; high dose, 400 mg/kg/day) were administered for 10 consecutive days by subcutaneous (s.c.) injection and oral gavage, respectively. Test materials were DEHP, 2-ethylhexyl oleate (IOO), 2-ethylhexyl stearate (IOS) and triethyl 2-acetylcitrate (ATEC). The rats were necropsied, and then the weights of five androgen-dependent tissues [ventral prostate, seminal vesicle, coagulating glands, levator ani-bulbocavernosus (LABC) muscle, paired Cowper’s glands, and glans penis] and four androgen-insensitive tissues (kidney, adrenal glands, spleen and liver) were measured. All test materials including DEHP did not exhibit any androgenic activity in the assay. On the contrary, antiandrogen-like activities were found in all test groups, and the order of the intensity was ATEC < DEHP < ISO < IOO in the five androgen-sensitive tissues. There was no statistical difference between low dose treatment and high dose treatment of all replacement candidate groups. In DEHP groups, high dose treatment exhibited significant weight gains in LABC and Glan Penis. There was no statistical difference in androgen-insensitive tissue measurements. Since the effects of ATEC treatment on the accessory sex organs were much less or not present at all when compared to those of DEHP, ATEC could be a strong candidate to replace DEHP. IOO treatment brought most severe weight reduction in all of androgen-sensitive tissues, so this material should be excluded for further screening of DEHP substitute selection. PMID:29707681

Focusing metasurface quantum-cascade laser with a near diffraction-limited beam

DOE PAGES

Xu, Luyao; Chen, Daguan; Itoh, Tatsuo; ...

2016-10-17

A terahertz vertical-external-cavity surface-emitting-laser (VECSEL) is demonstrated using an active focusing reflectarray metasurface based on quantum-cascade gain material. The focusing effect enables a hemispherical cavity with flat optics, which exhibits higher geometric stability than a plano-plano cavity and a directive and circular near-diffraction limited Gaussian beam with M 2 beam parameter as low as 1.3 and brightness of 1.86 × 10 6 Wsr –1m –2. As a result, this work initiates the potential of leveraging inhomogeneous metasurface and reflectarray designs to achieve high-power and high-brightness terahertz quantum-cascade VECSELs.

Impact of gate geometry on ionic liquid gated ionotronic systems

DOE PAGES

Wong, Anthony T.; Noh, Joo Hyon; Pudasaini, Pushpa Raj; ...

2017-01-23

Ionic liquid electrolytes are gaining widespread application as a gate dielectric used to control ion transport in functional materials. This letter systematically examines the important influence that device geometry in standard “side gate” 3-terminal geometries plays in device performance of a well-known oxygen ion conductor. We show that the most influential component of device design is the ratio between the area of the gate electrode and the active channel, while the spacing between these components and their individual shapes has a negligible contribution. Finally, these findings provide much needed guidance in device design intended for ionotronic gating with ionic liquids.

Verbal Final Exam in Introductory Biology Yields Gains in Student Content Knowledge and Longitudinal Performance

ERIC Educational Resources Information Center

Luckie, Douglas B.; Rivkin, Aaron M.; Aubry, Jacob R.; Marengo, Benjamin J.; Creech, Leah R.; Sweeder, Ryan D.

2013-01-01

We studied gains in student learning over eight semesters in which an introductory biology course curriculum was changed to include optional verbal final exams (VFs). Students could opt to demonstrate their mastery of course material via structured oral exams with the professor. In a quantitative assessment of cell biology content knowledge,…

To Gain Knowledge of How to Be Challenging: Preschool Mathematics Professional Development

ERIC Educational Resources Information Center

Helenius, Ola; Johansson, Maria L.; Lange, Troels; Meaney, Tamsin; Wernberg, Anna

2017-01-01

The use of freely-available web-based materials in professional development has rarely been investigated in mathematics education research. In this article, the responses to a survey by 267 preschool teachers about their use of online professional development materials are described. The web materials were based on a design model and the survey…

The Influence of Ability Level and Materials on Classificatory and Imaginative Behavior in Free Play.

ERIC Educational Resources Information Center

Phinney, Jean

A dissertation proposal involved a study to observe spontaneous behavior of children in interaction with materials in order to gain understanding of the factors that influence classificatory and imaginative behavior in free play. Children at two levels of ability in terms of classification skills were observed in interaction with materials at two…

The role of non-governmental organizations in the social and the health system.

PubMed

Piotrowicz, Maria; Cianciara, Dorota

2013-01-01

The article presents the definitions, objectives, fields and tasks of non-governmental organizations in social life, health system and health policy. In addition, the article addresses the issue of effectiveness and quality of NGOs' activity. The term "NGOs" (Non-governmental Organizations) includes different categories of entities that operate not to obtain financial gain, and also do not belong to the government sector. Non-governmental Organizations' fields of activity were described in the International Classification of Non-Profit Organizations (ICNPO). NGOs are an integral part of a democratic society. Sociological sciences emphasize their importance in enhancing social integration, implementation of the principle of subsidiarity, building civil society, social dialogue and participatory democracy. The main tasks of NGOs in the health system are providing services and health advocacy. Provision of services includes medical, social and psychological services as well as, integration activities, care and nursing, material and financial support, educational and information services and training. Health advocacy is a combination of individual and social actions designed to gain political commitment, policy support, social acceptance and systems support for a particular health goal or program. An important task carried out by NGOs is participation in the formation of health policy. The increasing role of NGOs in providing social services and the participation in political processes, result in the need to confirm the validity and credibility of their operation. One of the ways could be to introduce the mechanisms to assess quality and efficiency, such as registration as a part of a legal system, self-regulatory activities (card rules, codes of ethics), certification, participation in networks, monitoring and audit.

Analysis prediction of Indonesian banks (BCA, BNI, MANDIRI) using adaptive neuro-fuzzy inference system (ANFIS) and investment strategies

NASA Astrophysics Data System (ADS)

Trianto, Andriantama Budi; Hadi, I. M.; Liong, The Houw; Purqon, Acep

2015-09-01

Indonesian economical development is growing well. It has effect for their invesment in Banks and the stock market. In this study, we perform prediction for the three blue chips of Indonesian bank i.e. BCA, BNI, and MANDIRI by using the method of Adaptive Neuro-Fuzzy Inference System (ANFIS) with Takagi-Sugeno rules and Generalized bell (Gbell) as the membership function. Our results show that ANFIS perform good prediction with RMSE for BCA of 27, BNI of 5.29, and MANDIRI of 13.41, respectively. Furthermore, we develop an active strategy to gain more benefit. We compare between passive strategy versus active strategy. Our results shows that for the passive strategy gains 13 million rupiah, while for the active strategy gains 47 million rupiah in one year. The active investment strategy significantly shows gaining multiple benefit than the passive one.

The Evolution of Lineage-Specific Regulatory Activities in the Human Embryonic Limb

PubMed Central

Cotney, Justin; Leng, Jing; Yin, Jun; Reilly, Steven K.; DeMare, Laura E.; Emera, Deena; Ayoub, Albert E.; Rakic, Pasko; Noonan, James P.

2013-01-01

SUMMARY The evolution of human anatomical features likely involved changes in gene regulation during development. However, the nature and extent of human-specific developmental regulatory functions remain unknown. We obtained a genome-wide view of cis-regulatory evolution in human embryonic tissues by comparing the histone modification H3K27ac, which provides a quantitative readout of promoter and enhancer activity, during human, rhesus, and mouse limb development. Based on increased H3K27ac, we find that 13% of promoters and 11% of enhancers have gained activity on the human lineage since the human-rhesus divergence. These gains largely arose by modification of ancestral regulatory activities in the limb or potential co-option from other tissues and are likely to have heterogeneous genetic causes. Most enhancers that exhibit gain of activity in humans originated in mammals. Gains at promoters and enhancers in the human limb are associated with increased gene expression, suggesting they include molecular drivers of human morphological evolution. PMID:23827682

Differential mesolimbic and prefrontal alterations during reward anticipation and consummation in positive and negative schizotypy.

PubMed

Yan, Chao; Wang, Yi; Su, Li; Xu, Ting; Yin, Da-Zhi; Fan, Ming-Xia; Deng, Ci-Ping; Wang, Zhao-Xin; Lui, Simon S Y; Cheung, Eric F C; Chan, Raymond C K

2016-08-30

Schizotypy is associated with anhedonia. However, previous findings on the neural substrates of anhedonia in schizotypy are mixed. In the present study, we measured the neural substrates associated with reward anticipation and consummation in positive and negative schizotypy using functional MRI. The Monetary Incentive Delay task was administered to 33 individuals with schizotypy (18 positive schizotypy (PS),15 negative schizotypy (NS)) and 22 healthy controls. Comparison between schizotypy individuals and controls were performed using two-sample T tests for contrast images involving gain versus non-gain anticipation condition and gain versus non-gain consummation condition. Multiple comparisons were corrected using Monte Carlo Simulation correction of p<.05. The results showed no significant difference in brain activity between controls and schizotypy individuals as a whole during gain anticipation or consummation. However, during the consummatory phase, NS individuals rather than PS individuals showed diminished left amygdala and left putamen activity compared with controls. We observed significantly weaker activation at the left ventral striatum during gain anticipation in NS individuals compared with controls. PS individuals, however, exhibited enhanced right ventral lateral prefrontal activity. These findings suggest that different dimensions of schizotypy may be underlied by different neural dysfunctions in reward anticipation and consummation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Power systems for production, construction, life support and operations in space

NASA Technical Reports Server (NTRS)

Sovie, Ronald J.

1988-01-01

As one looks to man's future in space it becomes obvious that unprecedented amounts of power are required for the exploration, colonization, and exploitation of space. Activities envisioned include interplanetary travel and LEO to GEO transport using electric propulsion, Earth and lunar observatories, advance space stations, free-flying manufacturing platforms, communications platforms, and eventually evolutionary lunar and Mars bases. These latter bases would start as camps with modest power requirements (kWes) and evolve to large bases as manufacturing, food production, and life support materials are developed from lunar raw materials. These latter activities require very robust power supplies (MWes). The advanced power system technologies being pursued by NASA to fulfill these future needs are described. Technologies discussed will include nuclear, photovoltaic, and solar dynamic space power systems, including energy storage, power conditioning, power transmission, and thermal management. The state-of-the-art and gains to be made by technology advancements will be discussed. Mission requirements for a variety of applications (LEO, GEO, lunar, and Martian) will be treated, and data for power systems ranging from a few kilowatts to megawatt power systems will be represented. In addition the space power technologies being initiated under NASA's new Civilian Space Technology Initiative (CSTI) and Space Leadership Planning Group Activities will be discussed.

Power systems for production, construction, life support, and operations in space

NASA Technical Reports Server (NTRS)

Sovie, Ronald J.

1988-01-01

As one looks to man's future in space it becomes obvious that unprecedented amounts of power are required for the exploration, colonization, and exploitation of space. Activities envisioned include interplanetary travel and LEO to GEO transport using electric propulsion, earth and lunar observatories, advance space stations, free-flying manufacturing platforms, communications platforms, and eventually evolutionary lunar and Mars bases. These latter bases would start as camps with modest power requirements (kWes) and evolve to large bases as manufacturing, food production, and life support materials are developed from lunar raw materials. These latter activities require very robust power supplies (MWes). The advanced power system technologies being pursued by NASA to fulfill these future needs are described. Technologies discussed will include nuclear, photovoltaic, and solar dynamic space power systems, including energy storage, power conditioning, power transmission, and thermal management. The state-of-the-art and gains to be made by technology advancements will be discussed. Mission requirements for a variety of applications (LEO, GEO, lunar, and Martian) will be treated, and data for power systems ranging from a few kilowatts to megawatt power systems will be represented. In addition the space power technologies being initiated under NASA's new Civilian Space Technology Initiative (CSTI) and Space Leadership Planning Group Activities will be discussed.

Is Weight Gain after Smoking Cessation Inevitable?

ERIC Educational Resources Information Center

Talcott, Gerald W.; And Others

1995-01-01

Studied weight gain after smoking cessation in a naturalistic setting where all smokers quit and risk factors for postcessation weight gain were modified. Results showed no significant weight changes for smokers who quit. Suggests that an intensive program featuring dietary guidelines and increased physical activity can attenuate weight gain. (RJM)

Adaptation to nonlinear frequency compression in normal-hearing adults: a comparison of training approaches.

PubMed

Dickinson, Ann-Marie; Baker, Richard; Siciliano, Catherine; Munro, Kevin J

2014-10-01

To identify which training approach, if any, is most effective for improving perception of frequency-compressed speech. A between-subject design using repeated measures. Forty young adults with normal hearing were randomly allocated to one of four groups: a training group (sentence or consonant) or a control group (passive exposure or test-only). Test and training material differed in terms of material and speaker. On average, sentence training and passive exposure led to significantly improved sentence recognition (11.0% and 11.7%, respectively) compared with the consonant training group (2.5%) and test-only group (0.4%), whilst, consonant training led to significantly improved consonant recognition (8.8%) compared with the sentence training group (1.9%), passive exposure group (2.8%), and test-only group (0.8%). Sentence training led to improved sentence recognition, whilst consonant training led to improved consonant recognition. This suggests learning transferred between speakers and material but not stimuli. Passive exposure to sentence material led to an improvement in sentence recognition that was equivalent to gains from active training. This suggests that it may be possible to adapt passively to frequency-compressed speech.

Development of inorganic composite material based TiO2 for environmental application

NASA Astrophysics Data System (ADS)

Wahyuningsih, Sayekti; Handono Ramelan, Ari; Pramono, Edi; Purnawan, Candra; Anjani, Velina; Estianingsih, Puji; Rinawati, Ludfiaastu; Fadli, Khusnan

2016-02-01

Syntheses of various materials, for green energy nanotechnology applications have special attention to develop emerging areas, such as environmental as well as energy materials. Various approaches for preparing nanostructured photocatalysts, such as titanium dioxide, nickel oxide, lead oxide and their composites, was introduced. The use of nanomaterials as photocatalysts water detoxification by visible light photocatalyst of an inorganic composite as well as dye-sensitized photoreduction was also discussed. The enhancement of selective photocatalyst system was gain by the use of photocatalyst composite materials and applied potential bias on the system. The photoelectrocatalytic degradation of rhodamine B (RB) and Remazol Yellow FG (RY) as water contaminant using the thin film of modified TiO2 as the electrode was investigated via a series of potentials, and various pH. The result showed that the anodic potential bias influenced the degradation rate of water contaminant and exhibited better performance by the positive anodic bias was applied. The pH conditions influence the active dye structure whereas it will interact with inorganic semiconductor photocatalyst. Using dye- sensitized TiO2 system (DSTs), we have applied this system to build water decolorization as a novelty environmental remediation system.

Band Gap Engineering of Titania Systems Purposed for Photocatalytic Activity

NASA Astrophysics Data System (ADS)

Thurston, Cameron

Ab initio computer aided design drastically increases candidate population for highly specified material discovery and selection. These simulations, carried out through a first-principles computational approach, accurately extrapolate material properties and behavior. Titanium Dioxide (TiO2 ) is one such material that stands to gain a great deal from the use of these simulations. In its anatase form, titania (TiO2 ) has been found to exhibit a band gap nearing 3.2 eV. If titania is to become a viable alternative to other contemporary photoactive materials exhibiting band gaps better suited for the solar spectrum, then the band gap must be subsequently reduced. To lower the energy needed for electronic excitation, both transition metals and non-metals have been extensively researched and are currently viable candidates for the continued reduction of titania's band gap. The introduction of multicomponent atomic doping introduces new energy bands which tend to both reduce the band gap and recombination loss. Ta-N, Nb-N, V-N, Cr-N, Mo-N, and W-N substitutions were studied in titania and subsequent energy and band gap calculations show a favorable band gap reduction in the case of passivated systems.

Optical properties of nanowire metamaterials with gain

NASA Astrophysics Data System (ADS)

Lima, Joaquim; Adam, Jost; Rego, Davi; Esquerre, Vitaly; Bordo, Vladimir

2016-11-01

The transmittance, reflectance and absorption of a nanowire metamaterial with optical gain are numerically simulated and investigated. It is assumed that the metamaterial is represented by aligned silver nanowires embedded into a semiconductor matrix, made of either silicon or gallium phosphide. The gain in the matrix is modeled by adding a negative imaginary part to the dielectric function of the semiconductor. It is found that the optical coefficients of the metamaterial depend on the gain magnitude in a non-trivial way: they can both increase and decrease with gain depending on the lattice constant of the metamaterial. This peculiar behavior is explained by the field redistribution between the lossy metal nanowires and the amplifying matrix material. These findings are significant for a proper design of nanowire metamaterials with low optical losses for diverse applications.

Authentic science in education: Studies in course-based research at the United States Military Academy

NASA Astrophysics Data System (ADS)

Chase, Anthony M.

This dissertation consists of two studies at the United States Military Academy. Both studies involve the use of Course-based Undergraduate Research Experiences (CUREs). These experiences give students the ability to engage in undergraduate research at an early point in their academic career by replacing traditional laboratory activities with semester-long research projects. Both studies show an implementation of this type of instruction from the Center for Authentic Science Practice in Education (CASPiE). Study 1 shows the specific method of implementation at the military academy and explores learning-based outcomes. Primarily the outcome of critical thinking is demonstrated. Critical thinking is a construct that many curriculum developers and instructors want to foster within their students but often lack clear definitions or evaluation plans. This study gives a definition of critical thinking and an outcome of a critical thinking test. Significant gains in critical thinking are observed by students participating in the CURE as well as significant gains in three affective factors (Interest in Science/Chemistry, Authenticity, Perceived Learning). The gains in critical thinking are then further statistically linked to students’ perceptions of how authentically they saw the research in the course. If they felt that the course was demonstrating more authentic science practices, they gained significantly more in their critical thinking scores. The second study in this dissertation adds an additional transfer focus to the instructional materials that the CURE was meant to support. The treatment group in this study received instruction that was framed expansively. The expansively framed instruction showed students ways that the material was applicable outside of the course. The assessments and instructional materials of this study were transfer assessments with contrasting cases. Instances of negative or “overzealous transfer” were also reported. Findings suggest that students in the transfer-focused treatment condition display a deeper understanding of the inner workings of the Gas Chromatograph more so than the control group which focused on output of the instrument only. Analyses of instances of negative transfer or overzealous transfer in this study show a reduction in instances for the treatment groups. This can be theoretically attributed to the use of Inventing with Contrasting Cases for individuals in the treatment group as this is postulated to reduce instances of negative transfer. Future work in this area is suggested to incorporate studies with control-treatment comparisons across groups of larger populations to tease out significant differences of means on transfer assessments. Further, the transfer assessments used need to be comparable in level of difficulty as the ones in this study appeared to differ.

Short Term Innovative Research Program: Nanoengineered Reactive Materials for Tunable Ignition and Energy Release

DTIC Science & Technology

2009-01-01

Background Most conventional explosives can be roughly categorized into two classes – molecular materials and intermolecular composites. Molecular...materials refer to species such as the nitroalkanes (e.g. nitromethane ) and cyclic nitramines (e.g. TNAZ, RDX, HMX) that release chemical energy...alternative to conventional explosives that has been gaining increasing interest have been termed reactive materials, and are defined as systems in

Method and system for modulation of gain suppression in high average power laser systems

DOEpatents

Bayramian, Andrew James [Manteca, CA

2012-07-31

A high average power laser system with modulated gain suppression includes an input aperture associated with a first laser beam extraction path and an output aperture associated with the first laser beam extraction path. The system also includes a pinhole creation laser having an optical output directed along a pinhole creation path and an absorbing material positioned along both the first laser beam extraction path and the pinhole creation path. The system further includes a mechanism operable to translate the absorbing material in a direction crossing the first laser beam extraction laser path and a controller operable to modulate the second laser beam.

The use of sustainable materials for quick repair of aging bridges : phase II final report.

DOT National Transportation Integrated Search

2012-02-01

"During the last decade fiber reinforced polymer (FRP) materials have gained wide acceptance for repair and strengthening of existing infrastructures or to design new infrastructures due to their desirable properties (high strength to weight ratio, l...

TiO2/porous adsorbents: Recent advances and novel applications.

PubMed

MiarAlipour, Shayan; Friedmann, Donia; Scott, Jason; Amal, Rose

2018-01-05

This article reviews two interrelated areas of research: the first is the use of TiO 2 -supported adsorbent materials as enhanced heterogeneous photocatalysts and their application to various reactions for organic pollutant removal from air and water; the second is the combination of adsorbent materials with TiO 2 photocatalysts which aims to efficiently regenerate adsorbent materials using illumination. By reviewing both areas of research, the following topics are covered; (i) photocatalytic activation of TiO 2; (ii) related properties of photocatalytic TiO 2; (iii) shortcomings of photocatalytic processes; (iv) preparation methods of composite TiO 2 /adsorbent materials and their photocatalytic performance; (v) properties of common adsorbents and their applications for pollutant removal from air and water; (vi) adsorbent regeneration methods and their economic and operational issues; (vii) conclusions and future outlooks. This topic has not been previously reviewed to such an extent, and considerable knowledge can be gained from assembling the large number of studies on adsorption-photocatalysis combinations. As such, this review provides guidance for researchers working in the fields of environmental and chemical engineering focussing on organic pollutant removal and the engineering of new high performance photocatalytic TiO 2 -supported porous adsorbent materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Esthetic soft tissue management for teeth and implants.

PubMed

Fu, Jia-Hui; Su, Chuan-Yi; Wang, Hom-Lay

2012-09-01

Can newly introduced graft materials be successfully used in soft tissue augmentation around teeth and dental implants? An electronic search on the PubMed database for English articles published before March 31, 2012, was performed using the following key words: "root coverage," "soft tissue graft," "periodontal plastic surgery," "subepithelial connective graft (SCTG)," "acellular dermal matrix (ADM)," "guided tissue regeneration based root coverage (GTRC)," "recession defects," "mucogingival defects," "collagen matrix," "living cellular construct (LCC)," "mucograft," and "biologic agents." Literature featuring new soft tissue graft materials, such as ADM, collagen matrix, GTRC, and biologic agents, were included. Data showed (1) allogeneic grafts were comparable to SCTG in terms of mean complete root coverage (CRC), mean root coverage (RC), and mean amount of keratinized tissue (KT) gain; (2) xenogeneic collagen matrix was as comparable to SCTG in terms of mean amount of KT gain around teeth and dental implants but inferior in achieving RC; (3) GTRC was inferior to SCTG in terms of mean CRC and mean RC; (4) LCC was inferior to free gingival graft in terms of mean amount of KT gain but was superior in esthetics and patient satisfaction; and (5) adjunctive use of biologic agents did not exert a significant effect on mean CRC, mean RC, and mean amount of KT gain. Although these new materials do not surpass the gold standard (SCTG), they do provide improved patient satisfaction and esthetics, are available in abundance, and lead to reduced postoperative discomfort and surgical time. Copyright © 2012 Elsevier Inc. All rights reserved.

Motivation by potential gains and losses affects control processes via different mechanisms in the attentional network.

PubMed

Paschke, Lena M; Walter, Henrik; Steimke, Rosa; Ludwig, Vera U; Gaschler, Robert; Schubert, Torsten; Stelzel, Christine

2015-05-01

Attentional control in demanding cognitive tasks can be improved by manipulating the motivational state. Motivation to obtain gains and motivation to avoid losses both usually result in faster reaction times and stronger activation in relevant brain areas such as the prefrontal cortex, but little is known about differences in the underlying neurocognitive mechanisms of these types of motivation in an attentional control context. In the present functional magnetic resonance imaging (fMRI) study, we tested whether potential gain and loss as motivating incentives lead to overlapping or distinct neural effects in the attentional network, and whether one of these conditions is more effective than the other. A Flanker task with word stimuli as targets and distracters was performed by 115 healthy participants. Using a mixed blocked and event-related design allowed us to investigate transient and sustained motivation-related effects. Participants could either gain money (potential gain) or avoid losing money (potential loss) in different task blocks. Participants showed a congruency effect with increased reaction times for incongruent compared to congruent trials. Potential gain led to generally faster responses compared to the neutral condition and to stronger improvements than potential loss. Potential loss also led to shorter response times compared to the neutral condition, but participants improved mainly during incongruent and not during congruent trials. The event-related fMRI data revealed a main effect of congruency with increased activity in the left inferior frontal gyrus (IFG) and inferior frontal junction area (IFJ), the pre-supplementary motor area (pre-SMA), bilateral insula, intraparietal sulcus (IPS) and visual word form area (VWFA). While potential gain led to increased activity in a cluster of the IFJ and the VWFA only during incongruent trials, potential loss was linked to activity increases in these regions during incongruent and congruent trials. The block analysis revealed greater activity in gain and loss blocks compared to the neutral condition in most of these regions but no differences in the direct comparison of gain and loss blocks. These findings show that potential monetary gain and loss rely on different mechanisms: Gain was more effective in reducing the reaction time compared to potential loss. Brain data indicate that in the gain context attentional control is executed specifically in incongruent trials, whereas the loss context induces an unspecific increase of attentional control. These findings extend previous studies by providing evidence for diverging neural mechanisms for the effects of different types of motivation on attentional control, specifying the underlying activity patterns in task- and stimulus-related regions. Copyright © 2015 Elsevier Inc. All rights reserved.

20 CFR 416.973 - General information about work activity.

Code of Federal Regulations, 2013 CFR

2013-04-01

... operation of a business, this tends to show that you have the ability to work at the substantial gainful... ability to work at the substantial gainful activity level. Examples of the special conditions that may... 20 Employees' Benefits 2 2013-04-01 2013-04-01 false General information about work activity. 416...

20 CFR 416.973 - General information about work activity.

Code of Federal Regulations, 2014 CFR

2014-04-01

... operation of a business, this tends to show that you have the ability to work at the substantial gainful... ability to work at the substantial gainful activity level. Examples of the special conditions that may... 20 Employees' Benefits 2 2014-04-01 2014-04-01 false General information about work activity. 416...

20 CFR 416.973 - General information about work activity.

Code of Federal Regulations, 2012 CFR

2012-04-01

... operation of a business, this tends to show that you have the ability to work at the substantial gainful... ability to work at the substantial gainful activity level. Examples of the special conditions that may... 20 Employees' Benefits 2 2012-04-01 2012-04-01 false General information about work activity. 416...

Enrolment Purposes, Instructional Activities, and Perceptions of Attitudinal Learning in a Human Trafficking MOOC

ERIC Educational Resources Information Center

Watson, Sunnie Lee; Kim, Woori

2016-01-01

This study examines learner enrolment purposes, perceptions on instructional activities and their relationship to learning gains in a Massive Open Online Course (MOOC) for attitudinal change regarding human trafficking. Using an author-developed survey, learners reported their perceptions on instructional activities and learning gains within the…

26 CFR 1.355-3 - Active conduct of a trade or business.

Code of Federal Regulations, 2014 CFR

2014-04-01

... active and substantial management and operational functions. Generally, activities performed by the... gain or loss was recognized. Similarly, under section 355(b)(2)(D), the trade or business must not have... corporations) during that five-year period in a transaction in which gain or loss was recognized in whole or in...

A postcolonial feminist discourse analysis of urban Aboriginal women's description of pregnancy-related weight gain and physical activity.

PubMed

Darroch, Francine E; Giles, Audrey R

2016-02-01

Excessive weight gain and physical inactivity in pregnancy have been identified as risk factors for negative health outcomes for mothers and fetuses, particularly among Aboriginal women. In this paper we engage with postcolonial feminist theory and critical discourse analysis to examine the question, "how do urban Aboriginal women understand pregnancy-related weight gain and physical activity." We conducted focus groups and semi-structured interviews with 25 urban Aboriginal pregnant or postpartum women between the ages of 16 and 39 in Ottawa, Canada. Three prominent discourses emerged: Aboriginal women have different pregnancies than non-Aboriginal women because Aboriginal women gain more weight and are more likely to develop gestational diabetes; Aboriginal women feel personally responsible for and shameful about excessive weight gain; finally, Aboriginal women need culturally safe pregnancy resources. Our results illuminate the complex and often paradoxical ways in which discourses around weight gain and physical activity are produced and taken-up by Aboriginal women and their healthcare providers. Based on these findings, we argue there is a lack of accessible and culturally safe resources for urban Aboriginal women, specifically concerning weight gain and physical activity in pregnancy. We recommend the development of resources that are created for/by/with Aboriginal women to better address that issues that urban Aboriginal women themselves identify as being of key importance. Copyright © 2015 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.

Prototype Morphing Fan Nozzle Demonstrated

NASA Technical Reports Server (NTRS)

Lee, Ho-Jun; Song, Gang-Bing

2004-01-01

Ongoing research in NASA Glenn Research Center's Structural Mechanics and Dynamics Branch to develop smart materials technologies for aeropropulsion structural components has resulted in the design of the prototype morphing fan nozzle shown in the photograph. This prototype exploits the potential of smart materials to significantly improve the performance of existing aircraft engines by introducing new inherent capabilities for shape control, vibration damping, noise reduction, health monitoring, and flow manipulation. The novel design employs two different smart materials, a shape-memory alloy and magnetorheological fluids, to reduce the nozzle area by up to 30 percent. The prototype of the variable-area fan nozzle implements an overlapping spring leaf assembly to simplify the initial design and to provide ease of structural control. A single bundle of shape memory alloy wire actuators is used to reduce the nozzle geometry. The nozzle is subsequently held in the reduced-area configuration by using magnetorheological fluid brakes. This prototype uses the inherent advantages of shape memory alloys in providing large induced strains and of magnetorheological fluids in generating large resistive forces. In addition, the spring leaf design also functions as a return spring, once the magnetorheological fluid brakes are released, to help force the shape memory alloy wires to return to their original position. A computerized real-time control system uses the derivative-gain and proportional-gain algorithms to operate the system. This design represents a novel approach to the active control of high-bypass-ratio turbofan engines. Researchers have estimated that such engines will reduce thrust specific fuel consumption by 9 percent over that of fixed-geometry fan nozzles. This research was conducted under a cooperative agreement (NCC3-839) at the University of Akron.

Gain-Compensating Circuit For NDE and Ultrasonics

NASA Technical Reports Server (NTRS)

Kushnick, Peter W.

1987-01-01

High-frequency gain-compensating circuit designed for general use in nondestructive evaluation and ultrasonic measurements. Controls gain of ultrasonic receiver as function of time to aid in measuring attenuation of samples with high losses; for example, human skin and graphite/epoxy composites. Features high signal-to-noise ratio, large signal bandwidth and large dynamic range. Control bandwidth of 5 MHz ensures accuracy of control signal. Currently being used for retrieval of more information from ultrasonic signals sent through composite materials that have high losses, and to measure skin-burn depth in humans.

Doping-Induced Type-II to Type-I Transition and Interband Optical Gain in InAs/AlSb Quantum Wells

NASA Technical Reports Server (NTRS)

Kolokolov, K. I.; Ning, C. Z.

2003-01-01

We show that proper doping of the barrier regions can convert the well-known type-II InAs/AlSb QWs to type I, producing strong interband transitions comparable to regular type-I QWs. The interband gain for TM mode is as high as 4000 l/cm, thus providing an important alternative material system in the mid-infrared wavelength range. We also study the TE and TM gain as functions of doping level and intrinsic electron-hole density.

Mechanical properties and leaching modeling of activated incinerator bottom ash in Portland cement blends

DOE Office of Scientific and Technical Information (OSTI.GOV)

Onori, Roberta, E-mail: Roberta.onori@uniroma1.it; Polettini, Alessandra; Pomi, Raffaella

2011-02-15

In the present study the evolution of mechanical strength and the leaching behavior of major and trace elements from activated incinerator bottom ash/Portland cement mixtures were investigated. Chemical and mechanical activation were applied with the purpose of improving the reactivity of bottom ash in cement blends. Chemical activation made use of NaOH, KOH, CaCl{sub 2} or CaSO{sub 4}, which were selected for the experimental campaign on the basis of the results from previous studies. The results indicated that CaCl{sub 2} exhibited by far the best effects on the evolution of the hydration process in the mixtures; a positive effect onmore » mechanical strength was also observed when CaSO{sub 4} was used as the activator, while the gain in strength produced by KOH and NaOH was irrelevant. Geochemical modeling of the leaching solutions provided information on the mineral phases responsible for the release of major elements from the hardened materials and also indicated the important role played by surface sorption onto amorphous Fe and Al minerals in dictating the leaching of Pb. The leaching of the other trace metal cations investigated (Cu, Ni and Zn) could not be explained by any pure mineral included in the thermodynamic database used, suggesting they were present in the materials in the form of complex minerals or phase assemblages for which no consistent thermodynamic data are presently available in the literature.« less

Mechanical properties and leaching modeling of activated incinerator bottom ash in Portland cement blends.

PubMed

Onori, Roberta; Polettini, Alessandra; Pomi, Raffaella

2011-02-01

In the present study the evolution of mechanical strength and the leaching behavior of major and trace elements from activated incinerator bottom ash/Portland cement mixtures were investigated. Chemical and mechanical activation were applied with the purpose of improving the reactivity of bottom ash in cement blends. Chemical activation made use of NaOH, KOH, CaCl(2) or CaSO(4), which were selected for the experimental campaign on the basis of the results from previous studies. The results indicated that CaCl(2) exhibited by far the best effects on the evolution of the hydration process in the mixtures; a positive effect on mechanical strength was also observed when CaSO(4) was used as the activator, while the gain in strength produced by KOH and NaOH was irrelevant. Geochemical modeling of the leaching solutions provided information on the mineral phases responsible for the release of major elements from the hardened materials and also indicated the important role played by surface sorption onto amorphous Fe and Al minerals in dictating the leaching of Pb. The leaching of the other trace metal cations investigated (Cu, Ni and Zn) could not be explained by any pure mineral included in the thermodynamic database used, suggesting they were present in the materials in the form of complex minerals or phase assemblages for which no consistent thermodynamic data are presently available in the literature. Copyright © 2010 Elsevier Ltd. All rights reserved.

A Polymer-Dispersed Liquid Crystal-Based Dynamic Gain Equalizer

NASA Astrophysics Data System (ADS)

Barge, M.; Battarel, D.; de Bougrenet de La Tocnaye, J. L.

2005-08-01

This paper presents results obtained with a spatial light modulator (SLM) using a polymer-dispersed liquid-crystal (LC) material to provide dynamic gain equalization (DGE) for wavelength-division multiplexing (WDM) networks. We show the benefit of using a nonchannelized approach to adjust some physical parameters such as the ripple and the maximum obtainable attenuation slope for the spectra to be equalized. Particular attention is paid here to polarization dependence that can result from parasitic anisotropic multiple path interferences as well as induced anisotropy due to a planar transverse field when using a free-space SLM structure. In this frame, we demonstrate an original approach using a depolarizing prism that is only appropriate to such choice of material and that mitigates these effects. Finally, material engineering to widen the operating temperature range is also shortly presented in this paper.

Brush Seal Performance and Durability Issues Based on T-700 Engine Test Results

NASA Technical Reports Server (NTRS)

Hendricks, R. C.

1994-01-01

The integrity and performance of brush seals have been established. Severe bench and engine tests have shown high initial wear or run-in rates, material smearing at the interface, and bristle and rub-runner wear, but the brush seals did not fail. Short-duration (46 hr) experimental T-700 engine testing of the compressor discharge seal established over 1-percent engine performance gain (brush versus labyrinth). Long-term gains were established only as leakage comparisons, with the brush at least 20 percent better at controlling leakage. Long-term materials issues, such as wear and ultimately seal life, remain to be resolved. Future needs are cited for materials and analysis tools that account for heat generation, thermomechanical behavior, and tribological pairing to enable original equipment manufacturers to design high-temperature, high-surface-speed seals with confidence.

Efficacy of MedMyst: an Internet Teaching Tool for Middle School Microbiology.

PubMed

Miller, Leslie M; Moreno, Janette; Estrera, Vicky; Lane, David

2004-05-01

Can web-based technology be used to effectively introduce or reinforce aspects of microbiology to middle school students? This central hypothesis examines whether brief exposure to a web adventure format containing virtual lab experiments and computer games within an engaging story line can impact student learning. An episodic adventure series, MedMyst (http://medmyst.rice.edu), focuses on infectious diseases and the microbes that cause them. The website is not intended to replace classroom instruction, but rather to engage students in problem-solving activities not likely to be encountered elsewhere. It also provides scientists with a resource to introduce microbiology to adolescent audiences through outreach activities. In the online adventure, the player (student) enters a futuristic world in which he or she becomes a "Reconstructor," a member of an elite team charged with preventing the spread of infectious disease. The series consists of three "missions," each lasting approximately 30 to 40 minutes and designed to address a limited set of learning objectives. Middle school students participated in the creation of the characters and the stylized design through focus groups. Classroom teachers oversaw the alignment of the web adventure objectives with the National Science Content Standards. Scientists and clinicians reviewed the web adventure for content and accuracy. A field test involving over 700 students from nine different schools assessed the knowledge gains attributable to playing MedMyst. Gain scores from pretest to posttest indicated that middle school students retained important information by interacting with the online material for as little as 30 minutes per adventure; however, gains for high school students were less persuasive, perhaps indicating a different learning tool or content is required for this age audience.

Analysis of effective thermal conductivity of fibrous materials

NASA Technical Reports Server (NTRS)

Futschik, Michael W.; Witte, Larry C.

1993-01-01

The objective of this research is to gain a better understanding of the various mechanisms of heat transfer through fibrous materials and to gain insight into how fill-gas pressure influences the effective thermal conductivity. By way of first principles and some empiricism, two mathematical models are constructed to correlate experimental data. The data are obtained from a test series measuring the effective thermal conductivity of Nomex using a two-sided guarded hot-plate heater apparatus. Tests are conducted for certain mean temperatures and fill-gases over a range of pressures varying from vacuum to atmospheric conditions. The models are then evaluated to determine their effectiveness in representing the effective thermal conductivity of a fibrous material. The models presented herein predict the effective thermal conductivity of Nomex extremely well. Since the influence of gas conduction is determined to be the most influential component in predicting the effective thermal conductivity of a fibrous material, an improved representation of gas conduction is developed. Finally, some recommendations for extension to other random-oriented fiber materials are made concerning the usefulness of each model depending on their advantages and disadvantages.

Bioinspired Mesoporous Chiral Nematic Graphitic Carbon Nitride Photocatalysts modulated by Polarized Light.

PubMed

Lin, Wensheng; Hong, Wei; Sun, Lu; Yu, Di; Yu, Dingshan; Chen, Xudong

2018-01-10

Endowing materials with chirality and exploring the responses of the material under circularly polarized light (CPL) can enable further insight into the physical and chemical properties of the semiconductors to be gained, thus expanding on optoelectronic applications. Herein a bioinspired mesoporous chiral nematic graphitic carbon nitride (g-C 3 N 4 ) for efficient hydrogen evolution with polarized light modulation based on chiral nematic cellulose nanocrystal films prepared through silica templating is described. The mesoporous nematic chiral g-C 3 N 4 exhibits an ultrahigh hydrogen evolution rate of 219.9 μmol h -1 (for 20 mg catalyst), corresponding to a high enhancement factor of 55 when compared to the bulk g-C 3 N 4 under λ>420 nm irradiation. Furthermore, the chiral g-C 3 N 4 material exhibits unique photocatalytic activity modulated by CPL within the absorption region. This CPL-assisted photocatalytic regulation strategy holds great promise for a wide range of applications including optical devices, asymmetric photocatalysis, and chiral recognition/separation. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Excellence in Physics Education Award Talk: Sharing Active Learning Strategies in the Developed and Developing Worlds

NASA Astrophysics Data System (ADS)

Sokoloff, David

2010-02-01

Since the first series of National Microcomputer Based Laboratory (MBL) Institutes for Teachers of Physics in Summer, 1987, the Activity Based Physics Group (ABP) has presented numerous professional development institutes and workshops to thousands of high school, college and university faculty, sponsored by National Science Foundation, U.S. Department of Education, Howard Hughes Medical Institute and others. An overview of these programs and details of our instructional strategies will be presented. Some common features of these include: (1) motivating participants through introduction to active learning research literature, including exposure to conceptual evaluations and student learning gains in traditional and active learning courses, (2) exposing participants to active learning strategies through intensive hands-on work using classroom tested curricular materials, (3) relying on these materials to enhance teacher knowledge and correct misconceptions---when necessary, (4) providing opportunities to practice active learning instruction with other participants and (5) distributing or facilitating procurement of equipment and supplies needed to get started. Recently, ABP group members have been working with physics educators from other countries to introduce active learning strategies in the developing world. New programs such as Active Learning in Optics and Photonics (ALOP, UNESCO) and Physware (ICTP/UNESCO/IUPAP), that support active learning using low-cost equipment, have been developed for this purpose. To date, ALOP workshops have been presented to over 500 secondary and college faculty in Ghana, Tunisia, Morocco, India, Tanzania, Brazil, Mexico, Zambia, Cameroon, Colombia, Nepal and Chile, and the ALOP Training Manual has been translated into French and Spanish. The first Physware workshop, held at ICTP in Trieste in 2009, had 32 participants most of whom were from developing countries in Africa, Asia and South America. These programs will be described. )

The CHEM Study Story.

ERIC Educational Resources Information Center

Merrill, Richard J.; Ridgway, David W.

The history of the planning, funding, preparation of preliminary materials, teacher preparation, trial teaching, evaluation, revision and final publication of the CHEM Study materials is presented. The anecdotal account points out the difficulties encountered, the solutions found and the pitfalls avoided so that the experience gained may be useful…

Long-range parametric amplification of THz wave with absorption loss exceeding parametric gain.

PubMed

Wang, Tsong-Dong; Huang, Yen-Chieh; Chuang, Ming-Yun; Lin, Yen-Hou; Lee, Ching-Han; Lin, Yen-Yin; Lin, Fan-Yi; Kitaeva, Galiya Kh

2013-01-28

Optical parametric mixing is a popular scheme to generate an idler wave at THz frequencies, although the THz wave is often absorbing in the nonlinear optical material. It is widely suggested that the useful material length for co-directional parametric mixing with strong THz-wave absorption is comparable to the THz-wave absorption length in the material. Here we show that, even in the limit of the absorption loss exceeding parametric gain, the THz idler wave can grows monotonically from optical parametric amplification over a much longer distance in a nonlinear optical material until pump depletion. The coherent production of the non-absorbing signal wave can assist the growth of the highly absorbing idler wave. We also show that, for the case of an equal input pump and signal in difference frequency generation, the quick saturation of the THz idler wave predicted from a much simplified and yet popular plane-wave model fails when fast diffraction of the THz wave from the co-propagating optical mixing waves is considered.

Illicit Trafficking of Natural Radionuclides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedrich, Steinhaeusler; Lyudmila, Zaitseva

2008-08-07

Natural radionuclides have been subject to trafficking worldwide, involving natural uranium ore (U 238), processed uranium (yellow cake), low enriched uranium (<20% U 235) or highly enriched uranium (>20% U 235), radium (Ra 226), polonium (Po 210), and natural thorium ore (Th 232). An important prerequisite to successful illicit trafficking activities is access to a suitable logistical infrastructure enabling an undercover shipment of radioactive materials and, in case of trafficking natural uranium or thorium ore, capable of transporting large volumes of material. Covert en route diversion of an authorised uranium transport, together with covert diversion of uranium concentrate from anmore » operating or closed uranium mines or mills, are subject of case studies. Such cases, involving Israel, Iran, Pakistan and Libya, have been analyzed in terms of international actors involved and methods deployed. Using international incident data contained in the Database on Nuclear Smuggling, Theft and Orphan Radiation Sources (DSTO) and international experience gained from the fight against drug trafficking, a generic Trafficking Pathway Model (TPM) is developed for trafficking of natural radionuclides. The TPM covers the complete trafficking cycle, ranging from material diversion, covert material transport, material concealment, and all associated operational procedures. The model subdivides the trafficking cycle into five phases: (1) Material diversion by insider(s) or initiation by outsider(s); (2) Covert transport; (3) Material brokerage; (4) Material sale; (5) Material delivery. An Action Plan is recommended, addressing the strengthening of the national infrastructure for material protection and accounting, development of higher standards of good governance, and needs for improving the control system deployed by customs, border guards and security forces.« less

Illicit Trafficking of Natural Radionuclides

NASA Astrophysics Data System (ADS)

Friedrich, Steinhäusler; Lyudmila, Zaitseva

2008-08-01

Natural radionuclides have been subject to trafficking worldwide, involving natural uranium ore (U 238), processed uranium (yellow cake), low enriched uranium (<20% U 235) or highly enriched uranium (>20% U 235), radium (Ra 226), polonium (Po 210), and natural thorium ore (Th 232). An important prerequisite to successful illicit trafficking activities is access to a suitable logistical infrastructure enabling an undercover shipment of radioactive materials and, in case of trafficking natural uranium or thorium ore, capable of transporting large volumes of material. Covert en route diversion of an authorised uranium transport, together with covert diversion of uranium concentrate from an operating or closed uranium mines or mills, are subject of case studies. Such cases, involving Israel, Iran, Pakistan and Libya, have been analyzed in terms of international actors involved and methods deployed. Using international incident data contained in the Database on Nuclear Smuggling, Theft and Orphan Radiation Sources (DSTO) and international experience gained from the fight against drug trafficking, a generic Trafficking Pathway Model (TPM) is developed for trafficking of natural radionuclides. The TPM covers the complete trafficking cycle, ranging from material diversion, covert material transport, material concealment, and all associated operational procedures. The model subdivides the trafficking cycle into five phases: (1) Material diversion by insider(s) or initiation by outsider(s); (2) Covert transport; (3) Material brokerage; (4) Material sale; (5) Material delivery. An Action Plan is recommended, addressing the strengthening of the national infrastructure for material protection and accounting, development of higher standards of good governance, and needs for improving the control system deployed by customs, border guards and security forces.

78 FR 6772 - Failure To File Gain Recognition Agreements and Other Required Filings

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-31

... regulations that would amend the existing rules governing the consequences to U.S. persons for failing to file... current law, if a U.S. transferor fails to timely file an initial GRA, or fails to comply in any material... fails to timely file an annual certification), the U.S. transferor is subject to full gain recognition...

Women's Reflections on Formal Sex Education and the Advantage of Gaining Informal Sexual Knowledge through a Feminist Lens

ERIC Educational Resources Information Center

Edwards, Nichole

2016-01-01

By recognising the limitations of formal sex education, young people are able to seek out alternative material, gaining informal sexual knowledge through their own means and through a wide variety of sources. This paper derives from part of a larger study centred on feminism and heterosexuality in practice which features 17 feminist-identified…

Violet-to-Blue Gain and Lasing from Colloidal CdS Nanoplatelets: Low-Threshold Stimulated Emission Despite Low Photoluminescence Quantum Yield

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diroll, Benjamin T.; Talapin, Dmitri V.; Schaller, Richard D.

Amplified spontaneous emission (ASE) and lasing from solution-processed materials are demonstrated in the challenging violet-to-blue (430–490 nm) spectral region for colloidal nanoplatelets of CdS and newly synthesized core/shell CdS/ZnS nanoplatelets. Despite modest band-edge photoluminescence quantum yields of 2% or less for single excitons, which we show results from hole trapping, the samples exhibit low ASE thresholds. Furthermore, four-monolayer CdS samples show ASE at shorter wavelengths than any reported film of colloidal quantum-confined material. This work underlines that low quantum yields for single excitons do not necessarily lead to a poor gain medium. The low ASE thresholds originate from negligible dispersionmore » in thickness, large absorption cross sections of 2.8 × 10–14 cm–2, and rather slow (150 to 300 ps) biexciton recombination. We show that under higher-fluence excitation, ASE can kinetically outcompete hole trapping. Using nanoplatelets as the gain medium, lasing is observed in a linear optical cavity. This work confirms the fundamental advantages of colloidal quantum well structures as gain media, even in the absence of high photoluminescence efficiency.« less

Patterns of neural activity associated with honest and dishonest moral decisions

PubMed Central

Greene, Joshua D.; Paxton, Joseph M.

2009-01-01

What makes people behave honestly when confronted with opportunities for dishonest gain? Research on the interplay between controlled and automatic processes in decision making suggests 2 hypotheses: According to the “Will” hypothesis, honesty results from the active resistance of temptation, comparable to the controlled cognitive processes that enable the delay of reward. According to the “Grace” hypothesis, honesty results from the absence of temptation, consistent with research emphasizing the determination of behavior by the presence or absence of automatic processes. To test these hypotheses, we examined neural activity in individuals confronted with opportunities for dishonest gain. Subjects undergoing functional magnetic resonance imaging (fMRI) gained money by accurately predicting the outcomes of computerized coin-flips. In some trials, subjects recorded their predictions in advance. In other trials, subjects were rewarded based on self-reported accuracy, allowing them to gain money dishonestly by lying about the accuracy of their predictions. Many subjects behaved dishonestly, as indicated by improbable levels of “accuracy.” Our findings support the Grace hypothesis. Individuals who behaved honestly exhibited no additional control-related activity (or other kind of activity) when choosing to behave honestly, as compared with a control condition in which there was no opportunity for dishonest gain. In contrast, individuals who behaved dishonestly exhibited increased activity in control-related regions of prefrontal cortex, both when choosing to behave dishonestly and on occasions when they refrained from dishonesty. Levels of activity in these regions correlated with the frequency of dishonesty in individuals. PMID:19622733

Obesity and weight management at menopause.

PubMed

Proietto, Joseph

2017-06-01

Many women report gaining weight as they transition through menopause. For most, the weight gain is modest and can be reduced with a conscious effort to limit energy intake and increase energy expenditure. However, many women who are already overweight and obese will gain more weight as they approach menopause. The aims of this paper are to explain the reasons for menopausal weight gain and to detail a method for achieving and sustaining a substantial weight loss. Weight gain during menopause is predominantly due to a reduction in spontaneous activity. For women who are lean, advice about controlling energy intake and increasing physical activity may be all that is required to prevent weight gain. For women who are overweight and obese rapid weight loss is best achieved with the help of a very low energy diet. This must be followed by lifelong behaviour modification with or without the help of hunger-suppressing pharmacotherapy.

Spectral gain profile of a multi-stack terahertz quantum cascade laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bachmann, D., E-mail: dominic.bachmann@tuwien.ac.at; Deutsch, C.; Krall, M.

2014-11-03

The spectral gain of a multi-stack terahertz quantum cascade laser, composed of three active regions with emission frequencies centered at 2.3, 2.7, and 3.0 THz, is studied as a function of driving current and temperature using terahertz time-domain spectroscopy. The optical gain associated with the particular quantum cascade stacks clamps at different driving currents and saturates to different values. We attribute these observations to varying pumping efficiencies of the respective upper laser states and to frequency dependent optical losses. The multi-stack active region exhibits a spectral gain full width at half-maximum of 1.1 THz. Bandwidth and spectral position of themore » measured gain match with the broadband laser emission. As the laser action ceases with increasing operating temperature, the gain at the dominant lasing frequency of 2.65 THz degrades sharply.« less

Elaboration and optimization of tellurite-based materials for raman gain application

NASA Astrophysics Data System (ADS)

Guery, Guillaume

Tellurite-based oxide glasses have been investigated as promising materials for Raman gain applications, due to their good linear and nonlinear optical properties and their wide transparency windows in the near- and midwave infrared spectral region. Furthermore, their interesting thermal properties, i.e. low glass transition temperature and ability to be drawn into optical fibers, make tellurite-based glasses excellent candidates for optical fiber amplifiers. The estimation of the strength and spectral distribution of Raman gain in materials is commonly approximated from the spontaneous Raman scattering cross-section measurement. For development of tellurite-based glasses as Raman amplifiers, understanding the relationship between glass structure, vibrational response, and nonlinear optical properties (NLO) represents a key point. This dissertation provides an answer to the fundamental question of the PhD study: "What is the impact of the glass structure on Raman gain properties of tellurite glasses?" This dissertation summarizes findings on different tellurite-based glass families: the TeO2-TaO5/2-ZnO, TeO2-BiO 3/2-ZnO and TeO2-NbO5/2 glass networks. The influence of glass modifiers has been shown on the glass' properties. Introduction of tantalum oxide or zinc oxide has been shown to increase the glass' stability against crystallization, quantified by DeltaT, where DeltaT = Tx -Tg. Added to the variation of the glass viscosity, this attribute is critical in fabricating optical fibers and for the use of these materials in fiber-based Raman gain applications. The role of ZnO in the tellurite network and the mechanism for structural modification has been determined. This addition results in not only the largest DeltaT reported for these highly nonlinear glasses to date, but coincides with a commensurate decrease of the refractive index. A hydroxyl purification has been developed that when employed, resulted in high purity preform materials exhibiting a limited absorption in the transmission bandwidth in the near infrared (NIR). A reduction of 90 % in the OH content in candidate glasses was realized and core-only optical fiber drawn from this glass exhibited optical losses lower than 10 dB/m (either at 1.55 mum or 2.0 mum). This optical attenuation in a high Raman gain material represents a first in the design of both material attributes. The role of the glass modifiers on the glass structure has been investigated by a combination of vibrational spectroscopic methods, including IR absorption, as well as Raman and hyper-Raman scatterings. Following examination of fundamental vibrations present in the paratellurite crystal alpha-TeO2, these results were extended to interpret the structure of multi-component tellurite glasses. It has been verified that the transformation of the tellurite entities TeO4→TeO3+1→TeO3 is directly related to the percentage and type of glass modifiers present in the various tellurite glass matrix. The dramatic disruption in the continuity of Te-O linkages in the tellurite glass backbone's chains during the introduction of the modifier zinc oxide, leads to a systematic reduction in glass network connectivity. This structural change is accompanied by a significant change in the glass' normalized polarization curve (IPsiV/IHV ), a paramter which quantifies directly the depolymerization ratio (DR). This metric provides direct correlation with a reduction in the ternary glass' polarizability/hyperpolarizability and a decrease in the glass' nonlinear optical properties, specifically its Raman gain response. These results have validated and extended our understanding of the important role of Te-O-Te content and short, medium and longer-scale organization of the tellurite glass network and the corresponding impact on linear and nonlinear optical response and properties. Such fundamental knowledge of the relationship between vibrational response and structure, correlated to linear and nonlinear optical properties, allows the extension of this know-how to the development of customized optical components enabled by novel glass and glass ceramic optical materials.

Three-dimensional culture of dental pulp stem cells in direct contact to tricalcium silicate cements.

PubMed

Widbiller, M; Lindner, S R; Buchalla, W; Eidt, A; Hiller, K-A; Schmalz, G; Galler, K M

2016-03-01

Calcium silicate cements are biocompatible dental materials applicable in contact with vital tissue. The novel tricalcium silicate cement Biodentine™ offers properties superior to commonly used mineral trioxide aggregate (MTA). Objective of this study was to evaluate its cytocompatibility and ability to induce differentiation and mineralization in three-dimensional cultures of dental pulp stem cells after direct contact with the material. Test materials included a new tricalcium silicate (Biodentine™, Septodont, Saint-Maur-des-Fossés, France), MTA (ProRoot® MTA, DENSPLY Tulsa Dental Specialities, Johnson City, TN, USA), glass ionomer (Ketac™ Molar Aplicap™, 3M ESPE, Seefeld, Germany), human dentin disks and polystyrene. Magnetic activated cell sorting for to the surface antigen STRO-1 was performed to gain a fraction enriched with mesenchymal stem cells. Samples were allowed to set and dental pulp stem cells in collagen carriers were placed on top. Scanning electron microscopy of tricalcium silicate cement surfaces with and without cells was conducted. Cell viability was measured for 14 days by MTT assay. Alkaline phosphatase activity was evaluated (days 3, 7, and 14) and expression of mineralization-associated genes (COL1A1, ALP, DSPP, and RUNX2) was quantified by real-time quantitative PCR. Nonparametric statistical analysis for cell viability and alkaline phosphatase data was performed to compare different materials as well as time points (Mann-Whitney U test, α = 0.05). Cell viability was highest on tricalcium silicate cement, followed by MTA. Viability on glass ionomer cement and dentin disks was significantly lower. Alkaline phosphatase activity was lower in cells on new tricalcium silicate cement compared to MTA, whereas expression patterns of marker genes were alike. Increased cell viability and similar levels of mineralization-associated gene expression in three-dimensional cell cultures on the novel tricalcium silicate cement and mineral trioxide aggregate indicate that the material is cytocompatible and bioactive. The tested new tricalcium silicate cement confirms its suitability as an alternative to MTA in vital pulp therapy.

20 CFR 404.1573 - General information about work activity.

Code of Federal Regulations, 2014 CFR

2014-04-01

... business, this tends to show that you have the ability to work at the substantial gainful activity level... ability to do substantial gainful activity. Also, if you are forced to stop or reduce your work because of..., work done under special conditions may show that you have the necessary skills and ability to work at...

20 CFR 404.1573 - General information about work activity.

Code of Federal Regulations, 2012 CFR

2012-04-01

... business, this tends to show that you have the ability to work at the substantial gainful activity level... ability to do substantial gainful activity. Also, if you are forced to stop or reduce your work because of..., work done under special conditions may show that you have the necessary skills and ability to work at...

20 CFR 404.1573 - General information about work activity.

Code of Federal Regulations, 2013 CFR

2013-04-01

... business, this tends to show that you have the ability to work at the substantial gainful activity level... ability to do substantial gainful activity. Also, if you are forced to stop or reduce your work because of..., work done under special conditions may show that you have the necessary skills and ability to work at...

p53 mutations promote proteasomal activity.

PubMed

Oren, Moshe; Kotler, Eran

2016-07-27

p53 mutations occur very frequently in human cancer. Besides abrogating the tumour suppressive functions of wild-type p53, many of those mutations also acquire oncogenic gain-of-function activities. Augmentation of proteasome activity is now reported as a common gain-of-function mechanism shared by different p53 mutants, which promotes cancer resistance to proteasome inhibitors.

Facile fabrication of efficient organic CMOS circuits.

PubMed

Dzwilewski, Andrzej; Matyba, Piotr; Edman, Ludvig

2010-01-14

Organic electronic circuits based on a combination of n- and p-type transistors (so-called CMOS circuits) are attractive, since they promise the realization of a manifold of versatile and low-cost electronic devices. Here, we report a novel photoinduced transformation method, which allows for a particularly straightforward fabrication of highly functional organic CMOS circuits. A solution-deposited single-layer film, comprising a mixture of the n-type semiconductor [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) and the p-type semiconductor poly-3-hexylthiophene (P3HT) in a 3:1 mass ratio, was utilized as the common active material in an array of transistors. Selected film areas were exposed to laser light, with the result that the irradiated PCBM monomers were photochemically transformed into a low-solubility and high-mobility dimeric state. Thereafter, the entire film was developed via immersion into a developer solution, which selectively removed the nonexposed, and monomeric, PCBM component. The end result was that the transistors in the exposed film areas are n-type, as dimeric PCBM is the majority component in the active material, while the transistors in the nonexposed film areas are p-type, as P3HT is the sole remaining material. We demonstrate the merit of the method by utilizing the resulting combination of n-type and p-type transistors for the realization of CMOS inverters with a high gain of approximately 35.

5-Aminoimidazole-4-carboxamide ribonucleotide prevents fat gain following the cessation of voluntary physical activity.

PubMed

Ruegsegger, Gregory N; Sevage, Joseph A; Childs, Thomas E; Grigsby, Kolter B; Booth, Frank W

2017-11-01

What is the central question of this study? We investigated whether 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) could prevent acute increases in body fat and changes in omental and subcutaneous adipose tissue following the sudden transition from physical activity to physical inactivity. What is the main finding and its importance? AICAR prevented fat gains following the transition from physical activity to inactivity to levels comparable to rats that remained physically active. AICAR and continuous physical activity produced depot-specific changes in cyclin A1 mRNA and protein that were associated with the prevention of fat gain. These findings suggest that targeting AMP-activated protein kinase signalling could oppose rapid adipose mass growth. The transition from physical activity to inactivity is associated with drastic increases in 'catch-up' fat that in turn foster the development of many obesity-associated maladies. We tested whether 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) treatment would prevent gains in body fat following the sudden transition from a physically active state to an inactive state by locking a voluntary running wheel. Male Wistar rats were either sedentary (SED) or given wheel access for 4 weeks, at which time rats with wheels continued running (RUN), had their wheel locked (WL) or had WL with daily AICAR injection (WL + AICAR) for 1 week. RUN and WL + AICAR prevented gains in body fat compared with SED and WL (P < 0.001). Cyclin A1 mRNA, a marker of cell proliferation, was decreased in omental, but not subcutaneous adipose tissue, in RUN and WL + AICAR compared with SED and WL groups (P < 0.05). Both cyclin A1 mRNA and protein were positively associated with gains in fat mass (P < 0.05). Cyclin A1 mRNA in omental, but not subcutaneous, adipose tissue was negatively correlated with p-AMPK levels (P < 0.05). Differences in fat gain and omental mRNA and protein levels were independent of changes in food intake and in differences in select hypothalamic mRNAs. These findings suggest that AICAR treatment prevents acute gains in adipose tissue following physical inactivity to levels of rats that continuously run, and that together, continuous physical activity and AICAR could, at least initially in these conditions, exert similar inhibitory effects on adipogenesis in a depot-specific manner. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Neighborhood factors associated with physical activity and adequacy of weight gain during pregnancy

EPA Science Inventory

Healthy diet, physical activity, smoking, and adequate weight gain are all associated with maternal health and fetal growth during pregnancy. Neighborhood characteristics have been associated with poor maternal and child health outcomes, yet conceptualization of potential mechani...

Characterisation and properties of alkali activated pozzolanic materials

NASA Astrophysics Data System (ADS)

Bordeian, Georgeta Simona

Many of the waste materials produced from modem heavy industries are pozzalans, which develop cementitious properties when finely divided in the presence of free lime. This property allows a potential industrial use for this waste as a cement replacement material in concrete. An example of such a waste material is blast furnace slag from the smelting of iron and steel. The US produces 26 million tons of blast furnace slag annually. Most of the slag is slowly cooled in air and it makes a poor pozzolan. Only 1.6 million tons of the slag is available in the granulated form, which is suitable as a cementitious and pozzolanic admixture. Most European countries are well endowed with coal-fired power stations and this produces fly and bottom ash, flue gas desulphurisation (FGD) gypsum. However, less than 25% of the total ash from power stations has found an industrial use mainly in cement and concrete industry. This creates a massive waste-disposal problem. Disposal of unused fly ash in open tips and ponds, for example, creates pollution problems since the drainage of effluents from the ash in the deposit ponds threaten water supplies by polluting the ground water with traces of toxic chemicals.Recent research has concentrated on the alkali activation of waste pozzolanic materials, especially ground blast furnace slag. This thesis has investigated the alkali activation of low calcium fly ashes. These form very poor pozzolans and the alkali activation of the fly ash offers the opportunity for the large scale use of fly ash. Water glass was selected as a suitable activator for the fly ash. A comprehensive series of tests have been carried out to gain information on the effect of different parameters, such as proportion and composition of the constituent materials, curing conditions and casting methods, in developing high performance construction materials. Laboratory investigations were carried out to determine the following characteristics of alkali activated materials: density, water absorption, apparent porosity and coefficient of saturation, drying shrinkage, compressive creep, compressive, flexural and tensile splitting strength, dynamic modulus of elasticity, accelerated weathering (freeze-thaw cycle) resistance, fire resistance (temperatures up to 600°C), microstructure, macrostructure and investigation of hydration phases by SEM, ED AX, Digital-mapping and X-ray diffraction.The influence of key parameters e.g. slag content, curing method, water/binder ratio and water glass hardener content on the mechanical properties were determined. Optimisation of the alkali-activation of fly ash materials was achieved by blending this with other pozzolans such as silica fume and slags. Mechanical properties were further improved by using moulding pressures and by thermal treatment. The use of short fibre reinforcements was investigated to overcome microcracking, volumetric deformation and creep in the materials. The free shrinkage and creep of the materials agree with the model developed by Mangat and Azari for fibre reinforced Portland cement composites. Other additives were also investigated to improve workability, frost and water resistance and physical properties of the alkali activated materials. The fundamental relationships between chemical composition, hydration phases,microstructure and engineering properties (strength, durability and stability) of alkali activated materials were investigated. It is clear that strength development is a function of the hydration products developed and these are affected by the mix composition and the curing temperature. The current work found parameters such as the Si/Al ratio, the Ca/Si ratio and the Na20 content to be important. These chemical parameters decide the principal phases in the hydration products formed in alkali activated materials, between calcium silicate hydrate (C-S-H) and zeolite of the form (R[2]0 n Al[2]O[3] x SiO[2] r H[2]O).Overall the thesis shows the great potential of alkali activated materials to produce high strength construction materials. Limitation in the shrinkage of the materials can be overcome by the use of fibre reinforcement. At the end of the thesis limitations and suggestions for further work are made.

The Mitten Problem

ERIC Educational Resources Information Center

Keeley, Page

2011-01-01

The theory of "immaculate insulation" is prevalent among students. Research indicates that students often believe that some materials and objects, such as blankets or mittens, are intrinsically warm. Likewise, they believe that some objects and materials, such as metals, are cold. One effective way to gain insight into how students understand…

Commuting by car: weight gain among physically active adults.

PubMed

Sugiyama, Takemi; Ding, Ding; Owen, Neville

2013-02-01

Prolonged sitting, including time spent sitting in cars, is detrimentally associated with health outcomes. This study examined whether commuting by car was associated with adults' weight gain over 4 years. Among 822 adult residents of Adelaide, Australia, weight change was ascertained from self-reported weight at baseline (2003-2004) and at follow-up (2007-2008). Using time spent for car commuting and work status at baseline, participants were categorized as non-car commuters, occasional car commuters, and daily car commuters. Multilevel linear regression (conducted in 2012) examined associations of weight change with car-commuting category, adjusting for potential confounding variables, for the whole sample, and among those who were physically inactive or active (≥150 minutes/week) in their leisure time. For the overall sample, adjusted mean weight gain (95% CI) over 4 years was 1.26 (0.64, 1.89) kg for non-car commuters; 1.53 (0.69, 2.37) kg for occasional car commuters; and 2.18 (1.44, 2.92) kg for daily car commuters (p for trend=0.090). Stratified analyses found a stronger association for those with sufficient leisure-time physical activity. For non-car commuters with sufficient leisure-time physical activity, the adjusted mean weight gain was 0.46 (-0.43, 1.35) kg, which was not significantly greater than 0. Over 4 years, those who used cars daily for commuting tended to gain more weight than those who did not commute by car. This relationship was pronounced among those who were physically active during leisure time. Reducing sedentary time may prevent weight gain among physically active adults. Copyright © 2013 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

Soft Multifunctional Composites and Emulsions with Liquid Metals.

PubMed

Kazem, Navid; Hellebrekers, Tess; Majidi, Carmel

2017-07-01

Binary mixtures of liquid metal (LM) or low-melting-point alloy (LMPA) in an elastomeric or fluidic carrier medium can exhibit unique combinations of electrical, thermal, and mechanical properties. This emerging class of soft multifunctional composites have potential applications in wearable computing, bio-inspired robotics, and shape-programmable architectures. The dispersion phase can range from dilute droplets to connected networks that support electrical conductivity. In contrast to deterministically patterned LM microfluidics, LMPA- and LM-embedded elastomer (LMEE) composites are statistically homogenous and exhibit effective bulk properties. Eutectic Ga-In (EGaIn) and Ga-In-Sn (Galinstan) alloys are typically used due to their high conductivity, low viscosity, negligible nontoxicity, and ability to wet to nonmetallic materials. Because they are liquid-phase, these alloys can alter the electrical and thermal properties of the composite while preserving the mechanics of the surrounding medium. For composites with LMPA inclusions (e.g., Field's metal, Pb-based solder), mechanical rigidity can be actively tuned with external heating or electrical activation. This progress report, reviews recent experimental and theoretical studies of this emerging class of soft material architectures and identifies current technical challenges and opportunities for further advancement. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oligomannuronates from Seaweeds as Renewable Sources for the Development of Green Surfactants

NASA Astrophysics Data System (ADS)

Benvegnu, Thierry; Sassi, Jean-François

The development of surfactants based on natural renewable resources is a concept that is gaining recognition in detergents, cosmetics, and green chemistry. This new class of biodegradable and biocompatible products is a response to the increasing consumer demand for products that are both "greener", milder, and more efficient. In order to achieve these objectives, it is necessary to use renewable low-cost biomass that is available in large quantities and to design molecular structures through green processes that show improved performance, favorable ecotoxicological properties and reduced environmental impact. Within this context, marine algae represent a rich source of complex polysaccharides and oligosaccharides with innovative structures and functional properties that may find applications as starting materials for the development of green surfactants or cosmetic actives. Thus, we have developed original surfactants based on mannuronate moieties derived from alginates (cell-wall polyuronic acids from brown seaweeds) and fatty hydrocarbon chains derived from vegetable resources. Controlled chemical and/or enzymatic depolymerizations of the algal polysaccharides give saturated and/or unsaturated functional oligomannuronates. Clean chemical processes allow the efficient transformation of the oligomers into neutral or anionic amphiphilic molecules. These materials represent a new class of surface-active agents with promising foaming/emulsifying properties.

A flexible, transparent and high-performance gas sensor based on layer-materials for wearable technology

NASA Astrophysics Data System (ADS)

Zheng, Zhaoqiang; Yao, Jiandong; Wang, Bing; Yang, Guowei

2017-10-01

Gas sensors play a vital role among a wide range of practical applications. Recently, propelled by the development of layered materials, gas sensors have gained much progress. However, the high operation temperature has restricted their further application. Herein, via a facile pulsed laser deposition (PLD) method, we demonstrate a flexible, transparent and high-performance gas sensor made of highly-crystalline indium selenide (In2Se3) film. Under UV-vis-NIR light or even solar energy activation, the constructed gas sensors exhibit superior properties for detecting acetylene (C2H2) gas at room temperature. We attribute these properties to the photo-induced charger transfer mechanism upon C2H2 molecule adsorption. Moreover, no apparent degradation in the device properties is observed even after 100 bending cycles. In addition, we can also fabricate this device on rigid substrates, which is also capable to detect gas molecules at room temperature. These results unambiguously distinguish In2Se3 as a new candidate for future application in monitoring C2H2 gas at room temperature and open up new opportunities for developing next generation full-spectrum activated gas sensors.

A flexible, transparent and high-performance gas sensor based on layer-materials for wearable technology.

PubMed

Zheng, Zhaoqiang; Yao, Jiandong; Wang, Bing; Yang, Guowei

2017-10-13

Gas sensors play a vital role among a wide range of practical applications. Recently, propelled by the development of layered materials, gas sensors have gained much progress. However, the high operation temperature has restricted their further application. Herein, via a facile pulsed laser deposition (PLD) method, we demonstrate a flexible, transparent and high-performance gas sensor made of highly-crystalline indium selenide (In 2 Se 3 ) film. Under UV-vis-NIR light or even solar energy activation, the constructed gas sensors exhibit superior properties for detecting acetylene (C 2 H 2 ) gas at room temperature. We attribute these properties to the photo-induced charger transfer mechanism upon C 2 H 2 molecule adsorption. Moreover, no apparent degradation in the device properties is observed even after 100 bending cycles. In addition, we can also fabricate this device on rigid substrates, which is also capable to detect gas molecules at room temperature. These results unambiguously distinguish In 2 Se 3 as a new candidate for future application in monitoring C 2 H 2 gas at room temperature and open up new opportunities for developing next generation full-spectrum activated gas sensors.

Plant origin of Okinawan propolis: honeybee behavior observation and phytochemical analysis

NASA Astrophysics Data System (ADS)

Kumazawa, Shigenori; Nakamura, Jun; Murase, Masayo; Miyagawa, Mariko; Ahn, Mok-Ryeon; Fukumoto, Shuichi

2008-08-01

Propolis is a natural resinous product collected by honeybees from certain plants. It has gained popularity as a food and alternative medicine. Poplar and Baccharis are well known as the source plants of European and Brazilian propolis, respectively. However, the propolis from Okinawa, Japan, contains some prenylflavonoids not seen in other regions such as Europe and Brazil, suggesting that the plant origin of Okinawan propolis is a particular plant that grows in Okinawa. To identify the plant origin of Okinawan propolis, we observed the behavior of honeybees as they collected material from plants and caulked it inside the hive. Honeybees scraped resinous material from the surface of plant fruits of Macaranga tanarius and brought it back to their hive to use it as propolis. We collected samples of the plant and propolis, and compared their constituents by high-performance liquid chromatography with a photo-diode array detector. We also compared their 1,1-diphenyl-2-picryl-hydrazyl radical scavenging activity. The chemical constituents and biological activity of the ethanol extracts of the plant did not differ from those of propolis. This indicates directly that the plant origin of Okinawan propolis is M. tanarius.

Self-consistent optimization of [111]-AlGaInAs/InP MQWs structures lasing at 1.55 μm by a genetic algorithm

NASA Astrophysics Data System (ADS)

Saidi, Hosni; Msahli, Melek; Ben Dhafer, Rania; Ridene, Said

2017-12-01

Band structure and optical gain properties of [111]-oriented AlGaInAs/AlGaInAs-delta-InGaAs multi-quantum wells, subjected to piezoelectric field, for the near-infrared lasers diodes applications was proposed and investigated in this paper. By using genetic algorithm based on optimization technique we demonstrate that the structural parameters can be conveniently optimized to achieve high-efficiency laser diode performance at room temperature. In this work, significant optical gain for the wished emission wavelength at 1.55 μm and low threshold injection current are the optimization target. The end result of this optimization is a laser diode based on InP substrate using quaternary compound material of AlGaInAs in both quantum wells and barriers with different composition. It has been shown that the transverse electric polarized optical gain which reaches 3500 cm-1 may be acquired for λ = 1.55 μm with a threshold carrier density Nth≈1.31018cm-3, which is very promising to serve as an alternative active region for high-efficiency near-infrared lasers. Finally, from the design presented here, we show that it is possible to apply this technique to a different III-V compound semiconductors and wavelength ranging from deep-ultra-violet to far infrared.

Non-Dissipative Structural Evolutions in Granular Materials

NASA Astrophysics Data System (ADS)

Pouragha, Mehdi; Wan, Richard

2017-06-01

The structure of the contact network in granular assemblies can evolve due to either dissipative mechanisms such as sliding at contact points, or non-dissipative mechanisms through the phenomenon of contact gain and loss. Being associated with negligible deformations, non-dissipative mechanisms is actually active even in the small strain range of 10-3, especially in the case of densely packed assemblies. Hence, from a constitutive modelling point of view, it is crucial to be able to estimate such non-dissipative evolutions since both elastic and plastic properties of granular assemblies highly depend on contact network characteristics. The current study proposes an analytical scheme that allows us to estimate the non-dissipative contact gain/loss regime in terms of directional changes in the average contact force. The probability distribution of contact forces is used to compute the number of lost contact for each direction. Similarly, the number of newly formed contacts is estimated by considering the probability distribution of the gap between neighbouring particles. Based on the directional contact gain/loss computed, the changes in coordination number and fabric anisotropy can be found which, together with statistical treatments of Love-Weber stress expression, form a complete system of equations describing the evolution of other controlling microvariables. Finally, the results of the calculations have been compared with DEM simulations which verify the accuracy of the proposed scheme.

Improving Middle School Students’ Quantitative Literacy through Inquiry Lab and Group Investigation

NASA Astrophysics Data System (ADS)

Aisya, N. S. M.; Supriatno, B.; Saefudin; Anggraeni, S.

2017-02-01

The purpose of this study was to analyze the application of metacognitive strategies learning based Vee Diagram through Inquiry Lab and Group Investigation toward students’ quantitative literacy. This study compared two treatments on learning activity in middle school. The metacognitive strategies have applied to the content of environmental pollution at 7th grade. This study used a quantitative approach with quasi-experimental method. The research sample were the 7th grade students, involves 27 students in the experimental through Inquiry Lab and 27 students in the experimental through Group Investigation. The instruments that used in this research were pretest and posttest quantitative literacy skills, learning step observation sheets, and the questionnaire of teachers and students responses. As the result, N-gain average of pretest and posttest increased in both experimental groups. The average of posttest score was 61,11 for the Inquiry Lab and 54,01 to the Group Investigation. The average score of N-gain quantitative literacy skill of Inquiry Lab class was 0,492 and Group Investigation class was 0,426. Both classes of experiments showed an average N-gain in the medium category. The data has been analyzed statistically by using SPSS ver.23 and the results showed that although both the learning model can develop quantitative literacy, but there is not significantly different of improving students’ quantitative literacy between Inquiry Lab and Group Investigation in environmental pollution material.

An overview and process evaluation of TeleWalk: a telephone-based counseling intervention to encourage walking in older adults.

PubMed

Kolt, Gregory S; Oliver, Melody; Schofield, Grant M; Kerse, Ngaire; Garrett, Nick; Latham, Nancy K

2006-09-01

Despite the benefits associated with a physically active lifestyle, many older adults are insufficiently active to achieve health gain, and also exhibit decreased activity levels with age. Insufficient physical activity in this population is associated with increased morbidity, mortality and demand on health care services and expenditure. There is a clear need for effective intervention to encourage physical activity in older adults. The aim of this paper is to describe the development and participant evaluation of a randomized controlled trial of TeleWalk, a telephone-based motivational counseling intervention to encourage physical activity in adults aged 65 years and older. Participants (N = 186, mean age 74 +/- 6 years) were recruited through their General Practitioner (primary care physician) and randomized to either receive eight telephone counseling sessions and related printed materials over 3 months (intervention group) or participate in outcome assessments only (control group). Intervention group participants were mailed an anonymous evaluation questionnaire on intervention completion. A high response rate was achieved (70%). All respondents (100%) agreed or strongly agreed that a good overall level of service and support was provided, and that the counselor was understanding and supportive. Nearly all respondents agreed or strongly agreed that the service was professional, the counselor advice was helpful and motivating and the information provided was relevant (97, 95 and 89%, respectively). Most (87%) agreed or strongly agreed that the telephone calls encouraged them to be physically active. Among the participants who received printed material, most agreed or strongly agreed that these encouraged them to become or remain active. Findings from this evaluation can be used to inform such interventions and ensure their relevance to community-dwelling older adults.

The Principal's Role in Promoting Academic Gain.

ERIC Educational Resources Information Center

Gullatt, David E.; Lofton, Brenda D.

Principals encourage student academic gain by the ways in which they govern the school, build strong collaborative relationships, and organize and allocate professional work time. Because these activities are important predictors of academic achievement, along with quality teacher activities, further information is also provided about how…

Kinetics and Efficiency of H2O2 Activation by Iron-Containing Minerals and Aquifer Materials

PubMed Central

Pham, Anh Le-Tuan; Doyle, Fiona M.; Sedlak, David L.

2014-01-01

To gain insight into factors that control H2O2 persistence and ˙OH yield in H2O2-based in situ chemical oxidation systems, the decomposition of H2O2 and transformation of phenol were investigated in the presence of iron-containing minerals and aquifer materials. Under conditions expected during remediation of soil and groundwater, the stoichiometric efficiency, defined as the amount of phenol transformed per mole of H2O2 decomposed, varied from 0.005 to 0.28%. Among the iron-containing minerals, iron oxides were 2 to 10 times less efficient in transforming phenol than iron-containing clays and synthetic iron-containing catalysts. In both iron-containing mineral and aquifer materials systems, the stoichiometric efficiency was inversely correlated with the rate of H2O2 decomposition. In aquifer materials systems, the stoichiometric efficiency was also inversely correlated with the Mn content, consistent with the fact that the decomposition of H2O2 on manganese oxides does not produce ˙OH. Removal of iron and manganese oxide coatings from the surface of aquifer materials by extraction with citrate-bicarbonate-dithionite slowed the rate of H2O2 decomposition on aquifer materials and increased the stoichiometric efficiency. In addition, the presence of 2 mM of dissolved SiO2 slowed the rate of H2O2 decomposition on aquifer materials by over 80% without affecting the stoichiometric efficiency. PMID:23047055

Kinetics and efficiency of H2O2 activation by iron-containing minerals and aquifer materials.

PubMed

Pham, Anh Le-Tuan; Doyle, Fiona M; Sedlak, David L

2012-12-01

To gain insight into factors that control H(2)O(2) persistence and ·OH yield in H(2)O(2)-based in situ chemical oxidation systems, the decomposition of H(2)O(2) and transformation of phenol were investigated in the presence of iron-containing minerals and aquifer materials. Under conditions expected during remediation of soil and groundwater, the stoichiometric efficiency, defined as the amount of phenol transformed per mole of H(2)O(2) decomposed, varied from 0.005 to 0.28%. Among the iron-containing minerals, iron oxides were 2-10 times less efficient in transforming phenol than iron-containing clays and synthetic iron-containing catalysts. In both iron-containing mineral and aquifer materials systems, the stoichiometric efficiency was inversely correlated with the rate of H(2)O(2) decomposition. In aquifer materials systems, the stoichiometric efficiency was also inversely correlated with the Mn content, consistent with the fact that the decomposition of H(2)O(2) on manganese oxides does not produce ·OH. Removal of iron and manganese oxide coatings from the surface of aquifer materials by extraction with citrate-bicarbonate-dithionite slowed the rate of H(2)O(2) decomposition on aquifer materials and increased the stoichiometric efficiency. In addition, the presence of 2 mM of dissolved SiO(2) slowed the rate of H(2)O(2) decomposition on aquifer materials by over 80% without affecting the stoichiometric efficiency. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effectiveness of the use of question-driven levels of inquiry based instruction (QD-LOIBI) assisted visual multimedia supported teaching material on enhancing scientific explanation ability senior high school students

NASA Astrophysics Data System (ADS)

Suhandi, A.; Muslim; Samsudin, A.; Hermita, N.; Supriyatman

2018-05-01

In this study, the effectiveness of the use of Question-Driven Levels of Inquiry Based Instruction (QD-LOIBI) assisted visual multimedia supported teaching materials on enhancing senior high school students scientific explanation ability has been studied. QD-LOIBI was designed by following five-levels of inquiry proposed by Wenning. Visual multimedia used in teaching materials included image (photo), virtual simulation and video phenomena. QD-LOIBI assisted teaching materials supported by visual multimedia were tried out on senior high school students at one high school in one district in West Java. A quasi-experiment method with design one experiment group (n = 31) and one control group (n = 32) were used. Experimental group were given QD-LOIBI assisted teaching material supported by visual multimedia, whereas the control group were given QD-LOIBI assisted teaching materials not supported visual multimedia. Data on the ability of scientific explanation in both groups were collected by scientific explanation ability test in essay form concerning kinetic gas theory concept. The results showed that the number of students in the experimental class that has increased the category and quality of scientific explanation is greater than in the control class. These results indicate that the use of multimedia supported instructional materials developed for implementation of QD-LOIBI can improve students’ ability to provide explanations supported by scientific evidence gained from practicum activities and applicable concepts, laws, principles or theories.

Electroactive polymers for gaining sea power

NASA Astrophysics Data System (ADS)

Scherber, Benedikt; Grauer, Matthias; Köllnberger, Andreas

2013-04-01

Target of this article will be the energy harvesting with dielectric elastomers for wave energy conversion. The main goal of this article is to introduce a new developed material profile enabling a specific amount of energy, making the harvesting process competitive against other existing offshore generation technologies. Electroactive polymers offer the chance to start with small wave energy converters to gain experiences and carry out a similar development as wind energy. Meanwhile there is a consortium being formed in Germany to develop such materials and processes for future products in this new business area. In order to demonstrate the applicability of the technological advancements, a scale demonstrator of a wave energy generator will be developed as well.

20 CFR 416.975 - Evaluation guides if you are self-employed.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 6 months. We will not consider work you performed at the substantial gainful activity level for more... substantial gainful activity level. [46 FR 4872, Jan. 19, 1981, as amended at 48 FR 21940, May 16, 1983; 49 FR... Activity § 416.975 Evaluation guides if you are self-employed. (a) If you are a self-employed person. If...

The thermal and mechanical stability of composite materials for space structures

NASA Technical Reports Server (NTRS)

Tompkins, S. S.; Sykes, G. F.; Bowles, D. E.

1985-01-01

A continuing research objective of the National Aeronautical and Space Administration (NASA) is to develop advanced composite materials for space structures. The thrust of this research is to gain fundamental understanding of the performance of advanced composites in the space environment. The emphasis has been to identify and model changes in the thermal-physical properties due to induced damage and develop improved materials.

T-shaped emitter metal heterojunction bipolar transistors for submillimeter wave applications

NASA Technical Reports Server (NTRS)

Fung, Andy; Samoska, Lorene; Velebir, Jim; Siege, Peter; Rodwell, Mark; Paidi, Vamsi; Griffth, Zach; Urteaga, Miguel; Malik, Roger

2004-01-01

We report on the development of submillimeter wave transistors at JPL. The goal of the effort is to produce advance-reliable high frequency and high power amplifiers, voltage controlled oscillators, active multipliers, and high-speed mixed-signal circuits for space borne applications. The technology in development to achieve this is based on the Indium Phosphide (InP) Heterojunction Bipolar Transistor (HBT). The HBT is well suited for high speed, high power and uniform (across wafer) performance, due to the ability to tailor the material structure that electrons traverse through by well-controlled epitaxial growth methods. InP with its compatible lattice matched alloys such as indium gallium arsenide (InGaAs) and indium aluminium arsenide (InAlAs) provides for high electron velocities and high voltage breakdown capabilities. The epitaxial methods for this material system are fairly mature, however the implementation of high performance and reliable transistors are still under development by many laboratories. Our most recently fabricated, second generation mesa HBTs at JPL have extrapolated current gain cutoff frequency (FJ of 142GHz and power gain cutoff frequency (Fm,) of approximately 160GHz. This represents a 13% and 33% improvement of Ft and F, respectively, compared to the first generation mesa HBTs [l]. Analysis based on the University of California, Santa Barbara (UCSB) device model, RF device characteristics can be significantly improved by reducing base contact resistance and base metal contact width. We will describe our effort towards increasing transistor performance and yield.

RNA mediated assembly of nanostructures

NASA Astrophysics Data System (ADS)

Rouge, Jessica Lynn

The first chapter of this work presents a comprehensive look at RNA mediated nanoparticle formation. The overall goal of this research is to gain a deeper understanding of the RNA-particle formation mechanism and the basic properties of the materials selected by modified RNA molecules. Understanding such RNA-substrate interactions and how they translate into the physical and chemical characteristics of the nanoparticles they create are important fundamental concepts when considering these biotemplated materials as potential chemical catalysts. The RNA sequences discussed in the first chapter (referred to as Pdases) were discovered using RNA in vitro selection techniques. These Pdases were found to be capable of forming inorganic palladium (Pd) containing nanoparticles with impressive control over an individual particle's size and shape, despite incubation with the same organometallic precursor. This discovery held exciting implications for inorganic nanoparticle design while also generating numerous questions regarding the mechanism of RNA mediated particle growth. The central question that arose after this initial discovery was how could a biomolecule be used to tailor the physical size and shape of inorganic materials? Starting with a chemical proof designed to uncover the composition of the nanoparticles formed by RNA mediation, this chapter investigates the basic material properties of the nanoparticles while also introducing surprising results regarding the effect of multiple sequences on nanoparticle growth outcomes. In the second chapter, the experiments shift to developing methods to investigate nanoparticle growth mechanisms by fluorescence spectroscopy. A fluorescence polarization anisotropy (FPA) assay is presented in which the strengths of the technique are adapted for studying the formation of RNA mediated Pd nanoparticles in real time. This is a unique application of FPA, as it has been adapted to encompass both the biochemical and materials analysis of a single dynamic system. Although the initial studies described in chapter two focus on the growth kinetics of selected Pdases and their organometallic substrate (Pd2DBA3), it is envisioned that this technique can be used to study a variety of biotemplated systems in a similar fashion. For the experiments described, a key interest was to understand if the RNA governed the rates associated with nanoparticle formation and to gain deeper insight in to the potential growth mechanisms of RNA-nanoparticle constructs. Understanding such interactions could help identify the role RNA play in forming materials while also helping to shape the experimental design of future in vitro selections between RNA and materials. The strengths of these FPA experiments are described as well the associated kinetics observed for RNA mediated particle growth. In chapter three, the fundamental concepts surrounding RNA-nanoparticle interactions shifts to the first application-oriented study of RNA mediated nanoparticle formation for chemical catalysis. The product of a second materials selection is presented in which platinum (Pt) rich nanoparticles are formed using pyridyl modified RNA sequences. These RNA-Pt nanoparticle constructs are interfaced with cadmium sulfide (CdS) quantum dots in an effort to assess the ability of the RNA-Pt nanoparticles to serve as functional catalyst for the photocatalytic production of metal hydrides from aqueous solutions at neutral pH. Metal hydride formation is a crucial step in the challenging chemical reaction of water splitting. The results of this hybrid RNA-Pt/CdS water splitting catalyst are described and compared to more traditional catalyst designs. In the final chapter, the combination of concepts and insights gained as presented in chapters 1-3 are systematically combined into the first RNA in vitro selection for photochemically active materials. This novel selection utilizes an RNA library that is chemically modified such that it can both find and assess the ability of a material to perform photon-driven oxidation chemistry in a complex mixture. In order to conduct such a selection, a new DNA phosphoramidite was synthesized and attached to the RNA library prior to beginning the selection. The details of this synthesis are described. Later in this chapter, the results of this complex yet powerful in vitro selection are outlined. In closing, the prospect of using in vitro selection techniques for discovering other chemically active materials is discussed.

The Literacy Environment of Preschool Classrooms: Contributions to Children's Emergent Literacy Growth

ERIC Educational Resources Information Center

Guo, Ying; Justice, Laura M.; Kaderavek, Joan N.; McGinty, Anita

2012-01-01

This study examined the relations among features of the classroom physical literacy environment (book materials, literacy area and writing materials) and psychological literacy environment (instructional support), and preschool children's gains in two areas of emergent literacy over an academic year. Results showed that features of the physical…

Evaluation of a Supermarket Nutrition Education Program.

ERIC Educational Resources Information Center

Olson, Christine M.; And Others

1982-01-01

Evaluated a 16-week nutrition education program that combined a mass media campaign with provision of point-of-purchase materials in supermarkets. Small gains in nutrition knowledge were found, especially among those recalling exposure to the educational materials. Evidence of short-term increases in target food usage were also found. (Author/JN)

In vitro Alternative Methodologies for Central Nervous System Assessment: A Critique using Nanoscale Materials as an Example.

EPA Science Inventory

Identifying the potential health hazards to the central nervous system of a new family of materials presents many challenges. Whole-animal toxicity testing has been the tradition, but in vitro methods have been steadily gaining popularity. There are numerous challenges in testing...

Polyimide Prepregs With Improved Tack

NASA Technical Reports Server (NTRS)

Vanucci, R.

1987-01-01

Drape and tack improved without loss of strength. Composites made with PMR-15 (or equivalent) polyimides have gained acceptance as viable engineering materials for high-use-temperature applications. Acceptance due to both thermo-oxidative stability of PMR-15 (or equivalent) and ease which PMR-15 (or equivalent) prepreg materials processed into composite structures.

Does Transformational Leadership Encourage Teachers' Use of Digital Learning Materials

ERIC Educational Resources Information Center

Vermeulen, Marjan; Van Acker, Frederik; Kreijns, Karel; van Buuren, Hans

2015-01-01

To gain insight into how to promote teachers' use of digital learning materials (DLMs) in their pedagogical practices we adopted the Integrated Model of Behaviour Prediction to investigate the relationships between organizational and teacher-related variables. A representative sample of 772 teachers from primary, secondary or vocational education…

Preparing Students for Flipped or Team-Based Learning Methods

ERIC Educational Resources Information Center

Balan, Peter; Clark, Michele; Restall, Gregory

2015-01-01

Purpose: Teaching methods such as Flipped Learning and Team-Based Learning require students to pre-learn course materials before a teaching session, because classroom exercises rely on students using self-gained knowledge. This is the reverse to "traditional" teaching when course materials are presented during a lecture, and students are…

Leveraging Multi-University Collaboration to Develop Portable and Adaptable Online Course Content

ERIC Educational Resources Information Center

Frolik, Jeff; Flikkema, Paul G.; Weller, Tom; Haden, Carol; Shiroma, Wayne; Franklin, Rhonda

2013-01-01

Individual faculty and institutions regularly develop novel educational materials that could benefit others, but these innovations often fail to gain traction outside the developers' circle as barriers to adoption are numerous. We present evidence that development targeting adaptation, rather than complete adoption, of innovative materials and…

Radiation Damage Workshop report. [solar cells

NASA Technical Reports Server (NTRS)

Rahilly, W. P.

1980-01-01

The starting material, cell design/geometry, and cell processing/fabrication for silicon and gallium arsenide solar cells are addressed with reference to radiation damage. In general, it is concluded that diagnostic sensitivities and material purities are basic to making significant gains in end-of-life performance and thermal annealability. Further, GaAs material characterization is so sketchy that a well defined program to evaluate such material for solar cell application is needed to maximize GaAs cell technology benefits.

Dehalogenation and coupling of a polycyclic hydrocarbon on an atomically thin insulator.

PubMed

Dienel, Thomas; Gómez-Díaz, Jaime; Seitsonen, Ari P; Widmer, Roland; Iannuzzi, Marcella; Radican, Kevin; Sachdev, Hermann; Müllen, Klaus; Hutter, Jürg; Gröning, Oliver

2014-07-22

Catalytic activity is of pivotal relevance in enabling efficient and selective synthesis processes. Recently, covalent coupling reactions catalyzed by solid metal surfaces opened the rapidly evolving field of on-surface chemical synthesis. Tailored molecular precursors in conjunction with the catalytic activity of the metal substrate allow the synthesis of novel, technologically highly relevant materials such as atomically precise graphene nanoribbons. However, the reaction path on the metal substrate remains unclear in most cases, and the intriguing question is how a specific atomic configuration between reactant and catalyst controls the reaction processes. In this study, we cover the metal substrate with a monolayer of hexagonal boron nitride (h-BN), reducing the reactivity of the metal, and gain unique access to atomistic details during the activation of a polyphenylene precursor by sequential dehalogenation and the subsequent coupling to extended oligomers. We use scanning tunneling microscopy and density functional theory to reveal a reaction site anisotropy, induced by the registry mismatch between the precursor and the nanostructured h-BN monolayer.

Air-stable, solution-processed oxide p-n heterojunction ultraviolet photodetector.

PubMed

Kim, Do Young; Ryu, Jiho; Manders, Jesse; Lee, Jaewoong; So, Franky

2014-02-12

Air-stable solution processed all-inorganic p-n heterojunction ultraviolet photodetector is fabricated with a high gain (EQE, 25 300%). Solution-processed NiO and ZnO films are used as p-type and n-type ultraviolet sensitizing materials, respectively. The high gain in the detector is due to the interfacial trap-induced charge injection that occurs at the ITO/NiO interface by photogenerated holes trapped in the NiO film. The gain of the detector is controlled by the post-annealing temperature of the solution-processed NiO films, which are studied by X-ray photoelectron spectroscopy (XPS).

Children's decision making: When self-interest and moral considerations conflict.

PubMed

Tasimi, Arber; Johnson, Marcia K; Wynn, Karen

2017-09-01

When children's self-interests are at odds with their moral considerations, what do they do? In the current study of 5- and 6-year-olds (N=160), we asked (a) whether children would select the offering of a do-gooder over a neutral individual at a personal cost, (b) whether they would reject the offering of a wrongdoer over a neutral individual at a personal cost, and (c) whether these two types of decisions involve comparable levels of conflict. In the absence of material considerations, children preferred a nice character to a neutral one, but this preference was easily overcome for material gain; children accepted a larger offering from a neutral source over a smaller offering from a nice source. In contrast, children's aversion to negative characters was largely unaffected by the same material consideration; they rejected a larger offering from a mean source in favor of a smaller offering from a neutral source. In addition, children's response times indicated that deciding whether or not to "sell out" to a wrongdoer for personal gain engenders conflict but that deciding whether to take a lesser gain from a do-gooder does not. These findings indicate that children weigh both their own material interests and others' social behaviors when selecting social partners and, importantly, that an aversion to wrongdoers is a more powerful influence on these choices than an attraction to do-gooders. Copyright © 2017 Elsevier Inc. All rights reserved.

76 FR 25240 - Clothianidin; Pesticide Tolerances

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-04

... neurotoxicity were exhibited in both rats (decreased arousal, motor activity and locomotor activity) and mice... (decreased body weight gains and absolute thymus weights in pups, delayed sexual maturation and an increase.../day FQPA SF = 1x day.. based on decreased body weight gains and delayed sexual maturation, decreased...

Measuring radiation damage dynamics by pulsed ion beam irradiation: 2016 project annual report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kucheyev, Sergei O.

2017-01-04

The major goal of this project is to develop and demonstrate a novel experimental approach to access the dynamic regime of radiation damage formation in nuclear materials. In particular, the project exploits a pulsed-ion-beam method in order to gain insight into defect interaction dynamics by measuring effective defect interaction time constants and defect diffusion lengths. For Year 3, this project had the following two major milestones: (i) the demonstration of the measurement of thermally activated defect-interaction processes by pulsed ion beam techniques and (ii) the demonstration of alternative characterization techniques to study defect dynamics. As we describe below, both ofmore » these milestones have been met.« less

Cleaning Genesis Solar Wind Collectors with Ultrapure Water: Residual Contaminant Particle Analysis

NASA Technical Reports Server (NTRS)

Allton, J. H.; Wentworth, S. J.; Rodriquez, M. C.; Calaway, M. J.

2008-01-01

Additional experience has been gained in removing contaminant particles from the surface of Genesis solar wind collectors fragments by using megasonically activated ultrapure water (UPW)[1]. The curatorial facility has cleaned six of the eight array collector material types to date: silicon (Si), sapphire (SAP), silicon-on-sapphire (SOS), diamond-like carbon-on-silicon (DOS), gold-on-sapphire (AuOS), and germanium (Ge). Here we make estimates of cleaning effectiveness using image analysis of particle size distributions and an SEM/EDS reconnaissance of particle chemistry on the surface of UPW-cleaned silicon fragments (Fig. 1). Other particle removal techniques are reported by [2] and initial assessment of molecular film removal is reported by [3].

Reconfigurable optomechanical circulator and directional amplifier.

PubMed

Shen, Zhen; Zhang, Yan-Lei; Chen, Yuan; Sun, Fang-Wen; Zou, Xu-Bo; Guo, Guang-Can; Zou, Chang-Ling; Dong, Chun-Hua

2018-05-04

Non-reciprocal devices, which allow non-reciprocal signal routing, serve as fundamental elements in photonic and microwave circuits and are crucial in both classical and quantum information processing. The radiation-pressure-induced coupling between light and mechanical motion in travelling-wave resonators has been exploited to break the Lorentz reciprocity, enabling non-reciprocal devices without magnetic materials. Here, we experimentally demonstrate a reconfigurable non-reciprocal device with alternative functions as either a circulator or a directional amplifier via optomechanically induced coherent photon-phonon conversion or gain. The demonstrated device exhibits considerable flexibility and offers exciting opportunities for combining reconfigurability, non-reciprocity and active properties in single photonic devices, which can also be generalized to microwave and acoustic circuits.