IAEA Sampling Plan

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

Geist, William H.

2017-09-15

The objectives for this presentation are to describe the method that the IAEA uses to determine a sampling plan for nuclear material measurements; describe the terms detection probability and significant quantity; list the three nuclear materials measurement types; describe the sampling method applied to an item facility; and describe multiple method sampling.

Anal Sphincter Augmentation Using Biological Material.

PubMed

Alam, Nasra N; Narang, Sunil K; Köckerling, Ferdinand; Daniels, Ian R; Smart, Neil J

2015-01-01

The aim of this review is to provide an overview of the use of biological materials in the augmentation of the anal sphincter either as part of an overlapping sphincter repair (OSR) or anal bulking procedure. A systematic search of PubMed was conducted using the search terms "anal bulking agents," "anal sphincter repair," or "overlapping sphincter repair." Five studies using biological material as part of an overlapping sphincter repair (OSR) or as an anal bulking agent were identified. 122 patients underwent anal bulking with a biological material. Anorectal physiology was conducted in 27 patients and demonstrated deterioration in maximum resting pressure, and no significant change in maximum squeeze increment. Quality of life scores (QoLs) demonstrated improvements at 6 weeks and 6 months, but this had deteriorated at 12 months of follow up. Biological material was used in 23 patients to carry out an anal encirclement procedure. Improvements in QoLs were observed in patients undergoing OSR as well as anal encirclement using biological material. Incontinence episodes decreased to an average of one per week from 8 to 10 preoperatively. Sphincter encirclement with biological material has demonstrated improvements in continence and QoLs in the short term compared to traditional repair alone. Long-term studies are necessary to determine if this effect is sustained. As an anal bulking agent the benefits are short-term.

Deposition of carotenoids in egg yolk by short-term supplement of coloured carrot (Daucus carota) varieties as forage material for egg-laying hens.

PubMed

Hammershøj, Marianne; Kidmose, Ulla; Steenfeldt, Sanna

2010-05-01

Supplying egg-laying hens with different forage materials may influence egg production and quality. The aim of this study was to examine the short-term effects of standard feed plus 70 g day(-1) per hen of three coloured carrot varieties (orange, yellow and purple) as forage material in comparison with a standard feed control on egg production, egg yolk colour and deposition of carotenoids in the yolk. Carrot supplementation reduced feed intakes significantly, but not on a dry matter basis. Orange carrot treatment significantly reduced egg mass production, whereas yellow and purple carrot treatments did not differ from the control. Egg and yolk weights of all carrot-supplemented treatments were significantly lower than those of the control, but yolk percentages were similar. Yolk redness increased significantly in the order control < yellow < orange < purple. A similar trend was seen for yolk yellowness, but yellow and orange carrots reached the same level. Yolk colour and carotenoid contents correlated positively and significantly. In particular, purple carrot treatment increased the yolk content of lutein (>1.5-fold) and beta-carotene (>100-fold) compared with the control. Supplementing the feed of egg-laying hens with coloured carrots efficiently increased yolk colour parameters and carotenoid contents, which gives opportunities for improved nutritional value of eggs from forage material-supplemented hens.

Fusion Materials Research at Oak Ridge National Laboratory in Fiscal Year 2014

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

Wiffen, Frederick W.; Noe, Susan P.; Snead, Lance Lewis

2014-10-01

The realization of fusion energy is a formidable challenge with significant achievements resulting from close integration of the plasma physics and applied technology disciplines. Presently, the most significant technological challenge for the near-term experiments such as ITER, and next generation fusion power systems, is the inability of current materials and components to withstand the harsh fusion nuclear environment. The overarching goal of the ORNL fusion materials program is to provide the applied materials science support and understanding to underpin the ongoing DOE Office of Science fusion energy program while developing materials for fusion power systems. In doing so the programmore » continues to be integrated both with the larger U.S. and international fusion materials communities, and with the international fusion design and technology communities.« less

In-situ materials processing systems and bioregenerative life support systems interrelationships

NASA Technical Reports Server (NTRS)

Mignon, George V.; Frye, Robert J.

1992-01-01

The synergy and linkages between bioregenerative life support systems and the materials produced by in-situ materials processing systems was investigated. Such systems produce a broad spectrum of byproducts such as oxygen, hydrogen, processed soil material, ceramics, refractory, and other materials. Some of these materials may be utilized by bioregenerative systems either directly or with minor modifications. The main focus of this project was to investigate how these materials can be utilized to assist a bioregenerative life support system. Clearly the need to provide a sustainable bioregenerative life support system for long term human habitation of space is significant.

Occidental Geothermal, Inc. , Oxy geothermal power plant No. 1. Final environmental impact report

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

Not Available

1981-12-01

The project-specific environmental analysis covers the following: geology, soils, water resources, biology, air quality, noise, waste management, health, safety, transportation, energy and material resources, cultural resources, socioeconomics, public services, land use, and aesthetics. Other topics covered are: the cumulative envionmental analysis; unavoidable significant adverse environmental effects; irreversible environmental changes and irretrievable commitments of energy and materials; the relationship between local short-term uses of man's environment and the maintenance and enhancement of long-term productivity; growth-inducing impacts; and alternatives to the proposed action. (MHR)

Effect of flood conditions on the deterioration of porous clay-based brick

NASA Astrophysics Data System (ADS)

Mol, L.; Tomor, A.

2017-12-01

Man-made materials represent an increasingly large proportion of geomaterials that are used to build up a rapidly expanding urbanised landscape. The deterioration of such materials is of increasing concern, in particular in light of the projected increase in storm and flood events and their associated high water levels. The effect of prolonged saturation in porous materials, man-made as well as natural, can lead to accelerated deterioration. This can be of particular concern for load-bearing structural materials, for example bridges. In this study, the effect of moisture movement has been investigated for brick masonry, as one of the most commonly used porous building materials. Saturation of brick masonry can be of particular concern for historical masonry, such as masonry arch bridges in conjunction with under increasing levels of long-term traffic loading. While flooding can lead to scour and sudden collapse of bridges, saturation can also lead to accelerated medium and long-term deterioration. A series of small-scale laboratory tests have been carried out on brick masonry to identify the effects of saturation on the material properties and changes in the rate of deterioration. Brick masonry prisms have been loaded to failure under quasi-static and long-term cyclic compression and monitored with the help of acoustic emission technique, accelerometers, linear variable differential transformers (LVDTs), permeametry and brick surface hardness measurements. Under quasi-static loading saturated samples showed significant reduction in the load capacity and increased fracture development. Under fatigue loading the number of cycles to failure reduced significantly for saturated specimens and characteristic changes in material parameters have been related to stages of fatigue deterioration. Test results indicated that increasing flood events can accelerate moisture-related deterioration in porous brick masonry.

Effects of Laser Wavelength on Ablator Testing

NASA Technical Reports Server (NTRS)

White, Susan M.

2014-01-01

Wavelength-dependent or spectral radiation effects are potentially significant for thermal protection materials. NASA atmospheric entry simulations include trajectories with significant levels of shock layer radiation which is concentrated in narrow spectral lines. Tests using two different high powered lasers, the 10.6 micron LHMEL I CO2 laser and the near-infrared 1.07 micron fiber laser, on low density ablative thermal protection materials offer a unique opportunity to evaluate spectral effects. Test results indicated that the laser wavelength can impact the thermal response of an ablative material, in terms of bond-line temperatures, penetration times, mass losses, and char layer thicknesses.

Does stress enhance or impair memory consolidation?

PubMed

Trammell, Janet P; Clore, Gerald L

2014-01-01

Three experiments examined the hypothesis that stress-induced arousal enhances long-term memory for experiences associated with arousing events. Contrary to expectations, in each experiment exposure to a stressor (arm immersion in ice water) interfered with, rather than enhanced, long-term memory for associated material. Despite varying the stimuli (words, pictures), their emotional value (positive, negative, neutral), the time between learning and stress inductions (0 to 1 minute), and opportunities for post-learning rehearsal, each experiment produced a significant reversal of the hypothesised effect. That is, in each experiment, exposure to a stressor interfered with, rather than enhanced, long-term memory for associated material. We conclude that the relationship between stress and memory consolidation is more bounded than previously believed.

Related Studies in Long Term Lithium Battery Stability

NASA Technical Reports Server (NTRS)

Horning, R. J.; Chua, D. L.

1984-01-01

The continuing growth of the use of lithium electrochemical systems in a wide variety of both military and industrial applications is primarily a result of the significant benefits associated with the technology such as high energy density, wide temperature operation and long term stability. The stability or long term storage capability of a battery is a function of several factors, each important to the overall storage life and, therefore, each potentially a problem area if not addressed during the design, development and evaluation phases of the product cycle. Design (e.g., reserve vs active), inherent material thermal stability, material compatibility and self-discharge characteristics are examples of factors key to the storability of a power source.

Performance limiting processes in room temperature thallium bromide radiation detectors

NASA Astrophysics Data System (ADS)

Datta, Amlan; Becla, Piotr; Moed, Demi; Motakef, Shariar

2015-09-01

Thallium Bromide (TlBr) is a promising room-temperature radiation detector candidate with excellent charge transport properties. However, several critical issues are needed to be addressed before deployment of this material for long-term field applications. In this paper, the relevance and, scientific and technological progress made towards solving these challenges for TlBr have been discussed. The possible research pathways to mitigate the concerns related to this material have been analyzed and clearly established. Findings from novel experiments performed at CapeSym have revealed that the most significant factors for achieving long-term performance stability for TlBr devices involve physical and chemical conditions of the surface, residual stress, and choice of metal contacts. Palladium electrodes on TlBr devices resulted in a 20-fold improvement in the device lifetime when compared to its Br-etched Pt counterpart. Electron and hole contributions towards the spectroscopic response of the TlBr detector significantly depend on the interaction position of the incoming radiation and was clearly observed in this study. TlBr device fabrication techniques need significant improvement in order to attain reliable, repeatable, and stable, long-term performance.

Environmental impact of producing hardwood lumber using life-cycle inventory

Treesearch

Richard D. Bergman; S.A. Bowe

2007-01-01

Using sustainable building materials is gaining a significant presence in the United States therefore proving sustainability claims are becoming increasingly more important. Showing wood products as green building materials is vital for the long-term productivity of the wood building industry. This study examined hardwood lumber manufacturing using Life-Cycle Inventory...

Determination of elemental composition of substance lost following wear of all-ceramic materials.

PubMed

Dündar, Mine; Artunç, Celal; Toksavul, Suna; Ozmen, Dilek; Turgan, Nevbahar

2003-01-01

The aim of this study was to test the possible elemental release of four different all-ceramic materials in a wear machine to predict results about their long-term behavior in the oral environment. Four different all-ceramic materials with different chemical compositions were selected for the wear testing. A total of 20 cylindric samples, five for each ceramic group, were prepared according to the manufacturers' instructions. These were subjected to two-body wear testing in an artificial saliva medium under a covered unit with a computer-operated wear machine. The artificial saliva solutions for each material were analyzed for the determination of amounts of sodium, potassium, calcium, magnesium, and lithium elements released from the glass-ceramic materials. The differences between and within groups were statistically analyzed with a one-way ANOVA, followed by Duncan tests. The statistical analyses revealed no significant differences among Na, K, Ca, or Mg levels (P > .05) released from the leucite-reinforced groups, while there was a significant (P < .05) increase in Li release from the lithium disilicate group. Considerable element release to the artifical saliva medium was demonstrated in short-term wear testing. The lithia-based ceramic was more prone to Li release when compared with other elements and materials.

The effect of material choice on biofilm formation in a model warm water distribution system.

PubMed

Waines, Paul L; Moate, Roy; Moody, A John; Allen, Mike; Bradley, Graham

2011-11-01

Water distribution systems (WDS) are composed of a variety of materials and may harbour potential pathogens within surface-attached microbial biofilms. Biofilm formation on four plumbing materials, viz. copper, stainless steel 316 (SS316), ethylene propylene diene monomer (EPDM) and cross-linked polyethylene (PEX), was investigated using scanning electron microscope (SEM)/confocal microscopy, ATP-/culture-based analysis, and molecular analysis. Material 'inserts' were incorporated into a mains water fed, model WDS. All materials supported biofilm growth to various degrees. After 84 days, copper and SS316 showed no significant overall differences in terms of the level of biofilm formation observed, whilst PEX supported a significantly higher level of biofilm. EPDM exhibited gross contamination by a complex, multispecies biofilm, at a level significantly higher than was observed on the other materials, regardless of the analytical method used. PCR-DGGE analysis showed clear differences in the composition of the biofilm community on all materials after 84 days. The primary conclusion of this study has been to identify EPDM as a potentially unsuitable material for use as a major component in WDS.

Advances in dental materials.

PubMed

Vaderhobli, Ram M

2011-07-01

The use of materials to rehabilitate tooth structures is constantly changing. Over the past decade, newer material processing techniques and technologies have significantly improved the dependability and predictability of dental material for clinicians. The greatest obstacle, however, is in choosing the right combination for continued success. Finding predictable approaches for successful restorative procedures has been the goal of clinical and material scientists. This article provides a broad perspective on the advances made in various classes of dental restorative materials in terms of their functionality with respect to pit and fissure sealants, glass ionomers, and dental composites. Copyright © 2011 Elsevier Inc. All rights reserved.

Thinking Teacher Professional Learning Performatively: A Socio-Material Account

ERIC Educational Resources Information Center

Mulcahy, Dianne

2012-01-01

New socio-economic conditions have resulted in significant reconfiguration of professional learning in terms of the increasing integration of work into curriculum, pedagogy and inter-professional relationships. This article examines the significance of "more than human" dimensions for this learning, using resources provided by…

Shifting the paradigm of music instruction: implications of embodiment stemming from an augmented reality guitar learning system

PubMed Central

Keebler, Joseph R.; Wiltshire, Travis J.; Smith, Dustin C.; Fiore, Stephen M.; Bedwell, Jeffrey S.

2014-01-01

Musical instruction often includes materials that can act as a barrier to learning. New technologies using augmented reality may aid in reducing the initial difficulties involved in learning music by lowering these barriers characteristic of traditional instructional materials. Therefore, this set of studies examined a novel augmented reality guitar learning system (i.e., the Fretlight® guitar) in regards to current theories of embodied music cognition. Specifically, we examined the effects of using this system in comparison to a standard instructional material (i.e., diagrams). First, we review major theories related to musical embodiment and specify a niche within this research space we call embodied music technology for learning. Following, we explicate two parallel experiments that were conducted to address the learning effects of this system. Experiment 1 examined short-term learning effects within one experimental session, while Experiment 2 examined both short-term and long-term effects across two sessions spaced at a 2-week interval. Analyses demonstrated that, for many of our dependent variables, all participants increased in performance across time. Further, the Fretlight® condition consistently led to significantly better outcomes via interactive effects, including significantly better long term retention for the learned information across a 2 week time interval. These results are discussed in the context of embodied cognition theory as it relates to music. Potential limitations and avenues for future research are described. PMID:24999334

Hydrazine Materials Compatibility Database

NASA Astrophysics Data System (ADS)

Schmidt, E. W.

2004-10-01

Anhydrous hydrazine and its methyl derivatives MMH and UDMH have been safely used as monopropellants and bipropellant fuels in thousands of satellites and space probes, hundreds of expendable launch vehicles and hundreds of piloted reusable launch vehicle flights. The term hydrazine(s) is used here to describe the three propellant hydrazines and their mixtures. Over the years, a significant amount of experience has accumulated in the selection of compatible materials of construction for these and other rocket propellants. Only a few materials incompatibility issues have arisen in the recent past. New materials of construction have become available during the past decades which have not yet been extensively tested for long-term compatibility with hydrazine(s). These new materials promise lightweight (i. e., lighter weight) propulsion system designs and increased payloads in launch vehicles and satellites. Other new materials offer reduced contamination caused by leached ingredients, e. g. less silica leaching from diaphragms in propellant management devices in propellant tanks. This translates into longer mission life.

Gate-to-Gate Life-Cycle Inventory on Hardwood Sawmills in the Northeastern Region of the United States

Treesearch

Richard D. Bergman

2007-01-01

Using sustainable building materials is gaining a significant presence in the United States therefore proving sustainability claims are becoming increasingly more important. Certifying wood products as green building materials is vital for the long-term productivity of the wood building industry and for forest management. This study examined hardwood lumber...

Biomechanics in Schools.

ERIC Educational Resources Information Center

Vincent, J. F. V.

1980-01-01

Examines current usage of the term "biomechanics" and emphasizes the importance of differentiating between structure and material. Describes current prolects in biomechanics and lists four points about the educational significance of the field. (GS)

Color Stability of New Esthetic Restorative Materials: A Spectrophotometric Analysis.

PubMed

Poggio, Claudio; Vialba, Lodovico; Berardengo, Anna; Federico, Ricaldone; Colombo, Marco; Beltrami, Riccardo; Scribante, Andrea

2017-07-06

The aim of this in vitro study was to evaluate and compare the color stability of different esthetic restorative materials (one microfilled composite, one nanofilled composite, one nanoceramic composite, one microfilled hybrid composite, one microfilled hybrid composite, one nanohybrid Ormocer based composite and one supra-nano spherical hybrid composite) after exposure to different staining solutions (physiological saline, red wine, coffee). All materials were prepared and polymerized into silicon rings (2 mm × 6 mm × 8 mm) to obtain specimens identical in size. Thirty cylindrical specimens of each material were prepared. Specimens were immersed in staining solutions (physiological saline, coffee and red wine) over a 28-day test period. A colorimetric evaluation according to the CIE L*a*b* system was performed by a blind trained operator at 7, 14, 21, 28 days of the staining process. The Shapiro-Wilk test and ANOVA were applied to assess significant differences among restorative materials. A paired t -test was applied to test which CIE L*a*b* parameters significantly changed after immersion in staining solutions. All restorative materials showed significant color differences after immersion in coffee. Coffee caused a significant color change in all types of tested composite resins. Only Filtek Supreme XTE demonstrated a staining susceptibility to red wine; no other significant differences among the materials were demonstrated. Long-term exposure to some food dyes (coffee in particular) can significantly affect the color stability of modern esthetic restorative materials regardless of materials' different compositions.

Effect of long-term exposure to Low Earth Orbit (LEO) space environment

NASA Technical Reports Server (NTRS)

Zimcik, D. G.

1987-01-01

Data obtained from components and materials from the Solar Maximum Mission satellite are presented and compared to data for similar materials obtained from the Advanced Composite Materials Exposure to Space Experiment (ACOMEX) flown on Shuttle mission STS-41G. In addition to evaluation of surface erosion and mass loss that may be of importance to very long-term missions, comparisons of solar absorptance and thermal emittance measurements for both long and short term exposures were made. Although the ratio of absorptance over emittance can be altered by proper choice of materials to ensure a proper operating environment for the spacecraft, once the thermal design is established, it is important that the material properties not change in order to maintain the operating environment for many payload and bus items such as electronics, batteries, fuel, etc. However, data presented show significant changes after short exposure in low Earth environment. Moreover, the measured changes are shown to differ according to the manner of exposure, i.e., normal or oblique, which also affects the resultant eroded surface morphology. These results identify constraints to be considered in development of flight experiments or laboratory testing.

Does Stress Enhance or Impair Memory Consolidation?

PubMed Central

Trammell, Janet P.; Clore, Gerald L.

2014-01-01

Three experiments examined the hypothesis that stress-induced arousal enhances long term memory for experiences associated with an arousing events. Contrary to expectations, in each experiment exposure to a stressor (arm immersion in ice water) interfered with, rather than enhanced, long term memory for associated material. Despite varying the stimuli (words, pictures), their emotional value (positive, negative, neutral), the time between learning and stress inductions (0 to 1 minute), and opportunities for post-learning rehearsal, each experiment produced a significant reversal of the hypothesized effect. That is, in each experiment, exposure to a stressor interfered with, rather than enhanced, long term memory for associated material. We conclude that the relationship between stress and memory consolidation is more bounded than previously believed. PMID:23895111

Biological induced corrosion of materials II: New test methods and experiences from mir station

NASA Astrophysics Data System (ADS)

Klintworth, R.; Reher, H. J.; Viktorov, A. N.; Bohle, D.

1999-09-01

During previous long-term manned missions, more than 100 species of microorganisms have been identified on surfaces of materials (bacteria and fungi). Among them were potentially pathogenic ones (saprophytes) which are capable of active growth on artificial substrates, as well as technophilic bacteria and fungi causing damages (destruction and degradation) to various materials (metals and polymers), resulting in failures and disruptions in the functioning of equipment and hardware. Aboard a space vehicle some microclimatic parameters are optimal for microorganism growth: the atmospheric fluid condensate with its specific composition, chemical and/or antropogenic contaminants (human metobolic products, etc.) all are stimulating factors for the development of bacteria and mould fungi on materials of the interior and equipment of an orbital station during its operational phase(s). Especially Russian long-term missions (SALJUT, MIR) have demonstrated that uncontrolled interactions of microorganisms with materials will ultimately lead to the appearence of technological and medical risks, significantly influencing safety and reliability characteristics of individual as well as whole systems and/ or subsystems. For a first conclusion, it could be summarized, that countermeasures and anti-strategies focussing on Microbial Contamination Management (MCM) for the International Space Station (ISS, next long-term manned mission) at least require a new materials test approach. Our respective concept includes a combined age-ing/biocorrosion test sequence. It is represented here, as well as current status of MCM program, e.g. continuous monitoring (microbiological analyses), long-term disinfection, frequent cleaning methods, mathematical modeling of ISS, etc.

Topology optimization of hyperelastic structures using a level set method

NASA Astrophysics Data System (ADS)

Chen, Feifei; Wang, Yiqiang; Wang, Michael Yu; Zhang, Y. F.

2017-12-01

Soft rubberlike materials, due to their inherent compliance, are finding widespread implementation in a variety of applications ranging from assistive wearable technologies to soft material robots. Structural design of such soft and rubbery materials necessitates the consideration of large nonlinear deformations and hyperelastic material models to accurately predict their mechanical behaviour. In this paper, we present an effective level set-based topology optimization method for the design of hyperelastic structures that undergo large deformations. The method incorporates both geometric and material nonlinearities where the strain and stress measures are defined within the total Lagrange framework and the hyperelasticity is characterized by the widely-adopted Mooney-Rivlin material model. A shape sensitivity analysis is carried out, in the strict sense of the material derivative, where the high-order terms involving the displacement gradient are retained to ensure the descent direction. As the design velocity enters into the shape derivative in terms of its gradient and divergence terms, we develop a discrete velocity selection strategy. The whole optimization implementation undergoes a two-step process, where the linear optimization is first performed and its optimized solution serves as the initial design for the subsequent nonlinear optimization. It turns out that this operation could efficiently alleviate the numerical instability and facilitate the optimization process. To demonstrate the validity and effectiveness of the proposed method, three compliance minimization problems are studied and their optimized solutions present significant mechanical benefits of incorporating the nonlinearities, in terms of remarkable enhancement in not only the structural stiffness but also the critical buckling load.

Shore hardness and tensile bond strength of long-term soft denture lining materials.

PubMed

Kim, Bong-Jun; Yang, Hong-So; Chun, Min-Geoung; Park, Yeong-Joon

2014-11-01

Reduced softness and separation from the denture base are the most significant problems of long-term soft lining materials. The purpose of this study was to evaluate the durometer Shore A hardness and tensile bond strength of long-term soft denture lining materials and to investigate the correlation between these 2 properties. A group of 7 soft lining materials, 6 silicone based (Dentusil, GC Reline Soft, GC Reline Ultrasoft, Mucopren Soft, Mucosoft, Sofreliner Tough) and 1 acrylic resin based (Durabase), were evaluated for durometer Shore A hardness and tensile bond strength to heat-polymerized denture base resin (Lucitone 199). A specially designed split mold and loading assembly with a swivel connector were used for the durometer Shore A hardness test and tensile bond strength test to improve accuracy and facilitate measurement. Three specimens of each product were stored in a 37°C water bath, and durometer Shore A hardness tests were carried out after 24 hours and 28 days. A tensile bond strength test was carried out for 10 specimens of each product, which were stored in a 37°C water bath for 24 hours before the test. Repeated-measures ANOVA, the Kruskal-Wallis and Duncan multiple range tests, and the Spearman correlation were used for statistical analyses. The repeated-measures ANOVA found significant durometer Shore A hardness differences for the materials (P<.001) and the interaction effect (aging×materials) (P<.001). GC Reline Ultrasoft showed the lowest mean durometer Shore A hardness (21.30 ±0.29 for 24 hours, 34.73 ±0.47 for 28 days), and GC Reline Soft showed the highest mean durometer Shore A hardness (50.13 ±0.48 for 24 hours, 57.20 ±0.28 for 28 days). The Kruskal-Wallis test found a significant difference in the mean tensile bond strength values (P<.001). GC Reline Ultrasoft (0.82 ±0.32 MPa) and Mucopren Soft (0.96 ±0.46 MPa) had a significantly lower mean tensile bond strength (P<.05). GC Reline Soft had the highest mean tensile bond strength (2.99 ±0.43 MPa) (P<.05), and acrylic resin-based Durabase showed a significantly different tensile bond strength (1.32 ±0.16 MPa), except for Mucopren Soft, among the materials (P<.05). The tensile bond strength and Shore A hardness showed a statistically insignificant moderate positive correlation (r=0.571, P=.180 for Shore A hardness 24 hours versus tensile bond strength; r=0.607, P=.148 for Shore A hardness 28 days versus tensile bond strength). Within the limitations of this study, significant differences were found in durometer Shore A hardness (with aging time) and tensile bond strength among the materials. Adhesive failure was moderately correlated with durometer Shore A hardness, especially after 28 days, but was not significant. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Color Stability of New Esthetic Restorative Materials: A Spectrophotometric Analysis

PubMed Central

Vialba, Lodovico; Federico, Ricaldone; Colombo, Marco; Beltrami, Riccardo

2017-01-01

The aim of this in vitro study was to evaluate and compare the color stability of different esthetic restorative materials (one microfilled composite, one nanofilled composite, one nanoceramic composite, one microfilled hybrid composite, one microfilled hybrid composite, one nanohybrid Ormocer based composite and one supra-nano spherical hybrid composite) after exposure to different staining solutions (physiological saline, red wine, coffee). All materials were prepared and polymerized into silicon rings (2 mm × 6 mm × 8 mm) to obtain specimens identical in size. Thirty cylindrical specimens of each material were prepared. Specimens were immersed in staining solutions (physiological saline, coffee and red wine) over a 28-day test period. A colorimetric evaluation according to the CIE L*a*b* system was performed by a blind trained operator at 7, 14, 21, 28 days of the staining process. The Shapiro–Wilk test and ANOVA were applied to assess significant differences among restorative materials. A paired t-test was applied to test which CIE L*a*b* parameters significantly changed after immersion in staining solutions. All restorative materials showed significant color differences after immersion in coffee. Coffee caused a significant color change in all types of tested composite resins. Only Filtek Supreme XTE demonstrated a staining susceptibility to red wine; no other significant differences among the materials were demonstrated. Long-term exposure to some food dyes (coffee in particular) can significantly affect the color stability of modern esthetic restorative materials regardless of materials’ different compositions. PMID:28684672

14 CFR 253.9 - Retroactive changes to contracts of carriage

Code of Federal Regulations, 2010 CFR

2010-01-01

... (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS NOTICE OF TERMS OF CONTRACT OF CARRIAGE § 253.9 Retroactive... bought a ticket any material amendment to its contract of carriage that has significant negative...

14 CFR 253.9 - Retroactive changes to contracts of carriage.

Code of Federal Regulations, 2011 CFR

2011-01-01

... (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS NOTICE OF TERMS OF CONTRACT OF CARRIAGE § 253.9 Retroactive... bought a ticket any material amendment to its contract of carriage that has significant negative...

14 CFR 253.9 - Retroactive changes to contracts of carriage.

Code of Federal Regulations, 2012 CFR

2012-01-01

... (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS NOTICE OF TERMS OF CONTRACT OF CARRIAGE § 253.9 Retroactive... bought a ticket any material amendment to its contract of carriage that has significant negative...

14 CFR 253.9 - Retroactive changes to contracts of carriage.

Code of Federal Regulations, 2014 CFR

2014-01-01

... (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS NOTICE OF TERMS OF CONTRACT OF CARRIAGE § 253.9 Retroactive... bought a ticket any material amendment to its contract of carriage that has significant negative...

14 CFR 253.9 - Retroactive changes to contracts of carriage.

Code of Federal Regulations, 2013 CFR

2013-01-01

... (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS NOTICE OF TERMS OF CONTRACT OF CARRIAGE § 253.9 Retroactive... bought a ticket any material amendment to its contract of carriage that has significant negative...

Quercetin and isorhamnetin glycosides in onion (Allium cepa L.): varietal comparison, physical distribution, coproduct evaluation, and long-term storage stability.

PubMed

Lee, Jihyun; Mitchell, Alyson E

2011-02-09

During onion processing, the outer dried protective layer (outer paper layer) and first two fleshy leaf layers are removed. This coproduct material is a potential commercial source of flavonoids especially quercetin. In the following study, the flavonoid composition was determined in coproduct materials and the press cake (material generated after juice extraction) in several commercially important onion varieties grown in California. Flavonoids were characterized and quantified using LC-(ESI)MS/MS and HPLC. The long-term stability of quercetin glycosides was assessed in dried coproduct materials stored at 4 and 22 °C over a 12 month period. In all varieties, the predominant forms of quercetin were the quercetin 3,4'-O-glucoside and 4'-O-glucoside. The first layer had significantly higher levels of flavonoids than the outer paper, second, and inner flesh layers on a DW basis (p < 0.05). Allium cepa "Milestone" contained the highest levels (p < 0.05) of flavonoids (1703 mg/100 g on a dry weight basis (DW). Onion press cake had significantly higher levels of total quercetin as compared with fresh onions (p < 0.05). The levels of 4'-O-glucoside significantly decreased during the first month of storage and remained stable for 12 months of storage at either 4 or 22 °C (p < 0.05).

Color stability of esthetic restorative materials: a spectrophotometric analysis.

PubMed

Poggio, Claudio; Ceci, Matteo; Beltrami, Riccardo; Mirando, Maria; Wassim, Jaffal; Colombo, Marco

2016-12-01

Objective: The aim of this in vitro study was to evaluate the color stability of different restorative materials (one microfilled composite, one nanofilled composite, one nanohybrid composite and one Ormocer-based composite) after exposure to different staining solutions (coffee, coca-cola and red wine). Material and methods: All materials were polymerized into silicon rings (2 mm ×6 mm ×8 mm) to obtain specimens identical in size. Thirty cylindrical specimens of each material were prepared. They were immersed in staining solutions over a 28-day test period. A colorimetric evaluation according to the CIE L*a*b* system was performed by a blind trained operator at 7, 14, 21, 28 days of the staining process. The Shapiro-Wilk test and Kruskal-Wallis ANOVA were applied to assess significant differences among restorative materials. The paired t -test was applied to test which CIE L*a*b* parameters significantly changed after immersion in staining solutions. Results: All restorative materials showed clinically perceptible color differences after immersion in coffee. L* and b* values showed the highest variability. Coca cola and red wine did not influence the color stability for all restorative materials except for Filtek Supreme XTE. Conclusions: Coffee caused a significant color change in all types of tested composite resins. Filtek Supreme XTE demonstrated alone a staining susceptibility to red wine; no other significant differences among the materials were demonstrated. Long-term exposure to some food dyes (coffee in particular) can significantly affect the color stability of modern esthetic restorative materials regardless of materials' different composition.

RECENT ADVANCES IN HIGH TEMPERATURE ELECTROLYSIS AT IDAHO NATIONAL LABORATORY: STACK TESTS

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

X, Zhang; J. E. O'Brien; R. C. O'Brien

2012-07-01

High temperature steam electrolysis is a promising technology for efficient sustainable large-scale hydrogen production. Solid oxide electrolysis cells (SOECs) are able to utilize high temperature heat and electric power from advanced high-temperature nuclear reactors or renewable sources to generate carbon-free hydrogen at large scale. However, long term durability of SOECs needs to be improved significantly before commercialization of this technology. A degradation rate of 1%/khr or lower is proposed as a threshold value for commercialization of this technology. Solid oxide electrolysis stack tests have been conducted at Idaho National Laboratory to demonstrate recent improvements in long-term durability of SOECs. Electrolytesupportedmore » and electrode-supported SOEC stacks were provided by Ceramatec Inc., Materials and Systems Research Inc. (MSRI), and Saint Gobain Advanced Materials (St. Gobain), respectively for these tests. Long-term durability tests were generally operated for a duration of 1000 hours or more. Stack tests based on technology developed at Ceramatec and MSRI have shown significant improvement in durability in the electrolysis mode. Long-term degradation rates of 3.2%/khr and 4.6%/khr were observed for MSRI and Ceramatec stacks, respectively. One recent Ceramatec stack even showed negative degradation (performance improvement) over 1900 hours of operation. A three-cell short stack provided by St. Gobain, however, showed rapid degradation in the electrolysis mode. Improvements on electrode materials, interconnect coatings, and electrolyteelectrode interface microstructures contribute to better durability of SOEC stacks.« less

In vitro evaluation of five core materials.

PubMed

Gu, Steven; Rasimick, Brian J; Deutsch, Allan S; Musikant, Barry L

2007-01-01

This in vitro study determined the fracture strength of five core materials supported by two different endodontic dowels. Diametral tensile strength and microhardness of the three resin composite core materials used in this study were also tested. The fracture strength study used one lanthanide-reinforced flowable resin composite (Ti-Core Auto E), one titanium- and lanthanide-reinforced composite (Ti-Core), one lanthanide-reinforced composite (Ti-Core Natural), and two metal-reinforced glass ionomer core materials (Ketac Silver and GC Miracle Mix). Two types of dowels were used: a multitiered, split-shank threaded dowel with a flange (#1 Flexi-Flange) and one without a flange design (#1 Flexi-Post). The specimens were divided into ten groups. Each tooth/dowel and core specimen was placed in a special jig at 45 degrees and subjected to a load by a universal testing machine. The diametral tensile strength and the microhardness of the three resin composite core materials were measured by a universal testing machine and Barcol hardness tester, respectively. All test groups contained ten specimens. The fracture strength value of the resin composite core materials was significantly larger ( p < 0.0001) than those for the metal-reinforced glass-ionomer core materials. Analysis of variance (ANOVA) also showed that the Flexi-Flange dowel interacted with Ti-Core and Ti-Core Auto E to significantly ( p < 0.0013) increase the fracture strength relative to the Flexi-Post. One-way ANOVA revealed that there were no significant differences between them in terms of diametral tensile strength. The Barcol hardness values of the composite core materials were statistically different ( p < 0.0001), with the Ti-Core the highest, followed by Ti-Core Natural, then Ti-Core Auto E. Resin composite core material performed better than glass ionomer material in this in vitro study. The flowable composite core material performed about the same in terms of fracture strength and diametral tensile strength compared with nonflowable composites. Combined with certain core materials, the flange design increased the fracture strength of the tooth/dowel and core combination.

Material selection indices for design of surgical instruments with long tubular shafts.

PubMed

Nelson, Carl A

2013-02-01

In any medical device design process, material selection plays an important role. For devices which sustain mechanical loading, strength and stiffness requirements can be significant drivers of the design. This paper examines the specific case of minimally invasive surgical instruments, including robotic instruments, having long, tubular shafts. Material properties-based selection indices are derived for achieving high performance of these devices in terms of strength and stiffness, and the use of these indices for informing the medical device design problem is illustrated.

Refractive Index Measurement of Fibers Through Fizeau Interferometry

DTIC Science & Technology

2013-08-01

15. SUBJECT TERMS composite, transparent, refractive index, refractometry , interferometer 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...transparent fibers has long presented a significant challenge. Abbe refractometry , the typical measurement technique for bulk materials and liquids

Building Collections for All Time: The Issue of Significance

ERIC Educational Resources Information Center

Pymm, Bob

2006-01-01

One of the major roles adopted by libraries is the long-term preservation of selected material within their collections. Traditionally, this role comprised identifying individual physical objects or collections based upon the library's own view of its role and the significance of items in its collections. With the rapid growth of digital materials…

The Relationship of Academic Success and Selected Other Factors to Student Use of Library Materials at College of the Desert.

ERIC Educational Resources Information Center

Hostrop, Richard Winfred

This study found that, although some statistically-significant personal characteristics of students were associated with the use of library resources, they played only a minor role in the quantitive use of the materials. Instructors, in assigning term papers and speeches, provided the main impetus to student use of the library. Fewer than 5% of…

The Combined Influence of Molecular Weight and Temperature on the Aging and Viscoelastic Response of a Glassy Thermoplastic Polyimide

NASA Technical Reports Server (NTRS)

Nicholson, Lee M.; Whitley, Karen S.; Gates, Thomas S.

2000-01-01

The effect of molecular weight on the viscoelastic performance of an advanced polymer (LaRC-SI) was investigated through the use of creep compliance tests. Testing consisted of short-term isothermal creep and recovery with the creep segments performed under constant load. The tests were conducted at three temperatures below the glass transition temperature of five materials of different molecular weight. Through the use of time-aging-time superposition procedures, the material constants, material master curves and aging-related parameters were evaluated at each temperature for a given molecular weight. The time-temperature superposition technique helped to describe the effect of temperature on the timescale of the viscoelastic response of each molecular weight. It was shown that the low molecular weight materials have higher creep compliance and creep rate, and are more sensitive to temperature than the high molecular weight materials. Furthermore, a critical molecular weight transition was observed to occur at a weight-average molecular weight of M (bar) (sub w) 25000 g/mol below which, the temperature sensitivity of the time-temperature superposition shift factor increases rapidly. The short-term creep compliance data were used in association with Struik's effective time theory to predict the long-term creep compliance behavior for the different molecular weights. At long timescales, physical aging serves to significantly decrease the creep compliance and creep rate of all the materials tested.

High-capacity electrode materials for electrochemical energy storage: Role of nanoscale effects

DOE PAGES

Nanda, Jagjit; Martha, Surendra K.; Kalyanaraman, Ramki

2015-06-02

In this review, we summarize the current state-of-the art electrode materials used for high-capacity lithium-ion-based batteries and their significant role towards revolutionizing the electrochemical energy storage landscape in the area of consumer electronics, transportation and grid storage application. We discuss the role of nanoscale effects on the electrochemical performance of high-capacity battery electrode materials. Decrease in the particle size of the primary electrode materials from micron to nanometre size improves the ionic and electronic diffusion rates significantly. Nanometre-thick solid electrolyte (such as lithium phosphorous oxynitride) and oxides (such as Al 2O 3, ZnO, TiO 2 etc.) material coatings also improvemore » the interfacial stability and rate capability of a number of battery chemistries. Finally, we elucidate these effects in terms of different high-capacity battery chemistries based on intercalation and conversion mechanism.« less

Out-of-Autoclave Cure Composites

NASA Technical Reports Server (NTRS)

Hayes, Brian S.

2015-01-01

As the size of aerospace composite parts exceeds that of even the largest autoclaves, the development of new out-of-autoclave processes and materials is necessary to ensure quality and performance. Many out-of-autoclave prepreg systems can produce high-quality composites initially; however, due to long layup times, the resin advancement commonly causes high void content and variations in fiber volume. Applied Poleramic, Inc. (API), developed an aerospace-grade benzoxazine matrix composite prepreg material that offers more than a year out-time at ambient conditions and provides exceptionally low void content when out-of-autoclave cured. When compared with aerospace epoxy prepreg systems, API's innovation offers significant improvements in terms of out-time at ambient temperature and the corresponding tack retention. The carbon fiber composites developed with the optimized matrix technology have significantly better mechanical performance in terms of hot-wet retention and compression when compared with aerospace epoxy matrices. These composites also offer an excellent overall balance of properties. This matrix system imparts very low cure shrinkage, low coefficient of thermal expansion, and low density when compared with most aerospace epoxy prepreg materials.

Evaluation of accuracy of complete-arch multiple-unit abutment-level dental implant impressions using different impression and splinting materials.

PubMed

Buzayan, Muaiyed; Baig, Mirza Rustum; Yunus, Norsiah

2013-01-01

This in vitro study evaluated the accuracy of multiple-unit dental implant casts obtained from splinted or nonsplinted direct impression techniques using various splinting materials by comparing the casts to the reference models. The effect of two different impression materials on the accuracy of the implant casts was also evaluated for abutment-level impressions. A reference model with six internal-connection implant replicas placed in the completely edentulous mandibular arch and connected to multi-base abutments was fabricated from heat-curing acrylic resin. Forty impressions of the reference model were made, 20 each with polyether (PE) and polyvinylsiloxane (PVS) impression materials using the open tray technique. The PE and PVS groups were further subdivided into four subgroups of five each on the bases of splinting type: no splinting, bite registration PE, bite registration addition silicone, or autopolymerizing acrylic resin. The positional accuracy of the implant replica heads was measured on the poured casts using a coordinate measuring machine to assess linear differences in interimplant distances in all three axes. The collected data (linear and three-dimensional [3D] displacement values) were compared with the measurements calculated on the reference resin model and analyzed with nonparametric tests (Kruskal-Wallis and Mann-Whitney). No significant differences were found between the various splinting groups for both PE and PVS impression materials in terms of linear and 3D distortions. However, small but significant differences were found between the two impression materials (PVS, 91 μm; PE, 103 μm) in terms of 3D discrepancies, irrespective of the splinting technique employed. Casts obtained from both impression materials exhibited differences from the reference model. The impression material influenced impression inaccuracy more than the splinting material for multiple-unit abutment-level impressions.

Short-Term and Long-Term Effects of Orthopedic Biodegradable Implants

PubMed Central

Amini, Ami R.; Wallace, James S.; Nukavarapu, Syam P.

2012-01-01

Presently, orthopedic and oral/maxillofacial implants represent a combined $2.8 billion market, a figure expected to experience significant and continued growth. Although traditional permanent implants have been proved clinically efficacious, they are also associated with several drawbacks, including secondary revision and removal surgeries. Non-permanent, biodegradable implants offer a promising alternative for patients, as they provide temporary support and degrade at a rate matching tissue formation, and thus, eliminate the need for secondary surgeries. These implants have been in clinical use for nearly 25 years, competing directly with, or maybe even exceeding, the performance of permanent implants. The initial implantation of biodegradable materials, as with permanent materials, mounts an acute host inflammatory response. Over time, the implant degradation profile and possible degradation product toxicity mediate long-term biodegradable implant-induced inflammation. However, unlike permanent implants, this inflammation is likely to cease once the material disappears. Implant-mediated inflammation is a critical determinant for implant success. Thus, for the development of a proactive biodegradable implant that has the ability to promote optimal bone regeneration and minimal detrimental inflammation, a thorough understanding of short- and long-term inflammatory events is required. Here, we discuss an array of biodegradable orthopedic implants, their associated short- and long- term inflammatory effects, and methods to mediate these inflammatory events. PMID:22043969

Rahnella sp. strain EK12: Cell surface properties and diesel oil biodegradation after long-term contact with natural surfactants and diesel oil.

PubMed

Smułek, Wojciech; Zdarta, Agata; Guzik, Urszula; Dudzińska-Bajorek, Beata; Kaczorek, Ewa

2015-07-01

The changes in cell surface properties of Rahnella sp. strain EK12 and modifications in genetic material after long-term contact with saponins and rhamnolipids, were investigated. Rhamnolipids caused a decrease of hydrophobicity in liquid cultures compared with saponins. On the other hand, in cultures with rhamnolipids, the addition of diesel oil results in a rapid rise of cell surface hydrophobicity. The similar effect was not so significant in the presence of saponins. For the bacteria grown in the presence of saponins or rhamnolipids, but without diesel oil, the ratio of unsaturated to saturated fatty acids decreased, in comparison to the control culture. The differences observed in hydrophobicity, zeta potential and fatty acids profiles, indicated various mechanisms of an interaction between a surfactant and a bacterial cells. The results have also shown an impact of the long-term contact on changes in genetic material of Rahnella sp. strain EK12 cells. Moreover, the presence of saponins led to significant increase of diesel oil biodegradation. Copyright © 2015 Elsevier GmbH. All rights reserved.

Predator Acquisition Program Transition from Rapid to Standard Processes

DTIC Science & Technology

2012-06-08

47 Team Composition ...programs. Literature Review There is significant material written about Predator’s operational and acquisition success. For example, Dr. Mike...Reconnaissance Office (DARO), the organization that demonstrated medium altitude *The terms UAV and

Dye Sensitized Solar Cells for Economically Viable Photovoltaic Systems.

PubMed

Jung, Hyun Suk; Lee, Jung-Kun

2013-05-16

TiO2 nanoparticle-based dye sensitized solar cells (DSSCs) have attracted a significant level of scientific and technological interest for their potential as economically viable photovoltaic devices. While DSSCs have multiple benefits such as material abundance, a short energy payback period, constant power output, and compatibility with flexible applications, there are still several challenges that hold back large scale commercialization. Critical factors determining the future of DSSCs involve energy conversion efficiency, long-term stability, and production cost. Continuous advancement of their long-term stability suggests that state-of-the-art DSSCs will operate for over 20 years without a significant decrease in performance. Nevertheless, key questions remain in regards to energy conversion efficiency improvements and material cost reduction. In this Perspective, the present state of the field and the ongoing efforts to address the requirements of DSSCs are summarized with views on the future of DSSCs.

Effect of short-term water storage on the elastic properties of some dental restorative materials--A resonant ultrasound spectroscopy study.

PubMed

Pastila, Pirjo; Lassila, Lippo V J; Jokinen, Mikko; Vuorinen, Jyrki; Vallittu, Pekka K; Mäntylä, Tapio

2007-07-01

This study was aimed to determine if short-term water storage would change elastic properties of dental composite materials. Particulate filler composite resin and continuous unidirectional E-glass FRC materials were photopolymerized and additionally post-polymerized by heat for testing elastic properties with the Resonance Ultrasound Spectroscopy method as a function of time in water storage. The test specimens were stored in 37 degrees C water for up to 30 days. About 1% weight increase due to water sorption was observed in both materials with both polymerization methods. Water sorption did not change the resonance frequencies towards lower values, indicating no significant decrease in elastic properties in these materials. Because of high damping of the polymer composite materials leading to wide resonance peaks and low number of the recorded peaks, accurate determination of the elastic properties was not possible. Results suggest that the most likely explanation for the previously observed decrease in bending stiffness of FRC materials is the decreased yield limit of the hydrated polymer matrix. It is important to recognize that water sorption has the effect on mechanical properties of dental composite materials by changing the yield limit of the matrix rather than by changing the elastic properties of the material.

Asbestos/NESHAP regulated asbestos-containing-materials guidance

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

Shafer, R.; Throwe, S.; Salgado, O.

In the initial Asbestos NESHAP rule promulgated in 1973, a distinction was made between building materials that would readily release asbestos fibers when damaged or disturbed and those materials that were unlikely to result in significant fiber release. The terms friable and nonfriable were used to make this distinction. EPA has since determined that, if severely damaged, otherwise nonfriable materials can release significant amounts of asbestos fibers. Regulated Asbestos-Containing Material (RACM) is (a) friable asbestos material, (b) Category 1 nonfriable ACM that has become friable, (c) Category 1 nonfriable ACM that will be or has been subjected to sanding, grinding,more » cutting, or abrading, or (d) Category 2 nonfriable ACM that has a high probability of becoming or has become crumbled, pulverized, or reduced to powder by the forces expected to act on the material in the course of demolition or renovation operations. The purpose of the document is to assist asbestos inspectors and the regulated community in determining whether or not a material is RACM and thus subject to the Asbestos NESHAP.« less

Surface hardness of different restorative materials after long-term immersion in sports and energy drinks.

PubMed

Erdemir, Ugur; Yildiz, Esra; Eren, Meltem Mert; Ozel, Sevda

2012-01-01

The purpose of this study was to evaluate the effect of sports and energy drinks on the surface hardness of different restorative materials over a 6-month period. Forty-two disk-shaped specimens were prepared for each of the four restorative materials tested: Compoglass F, Filtek Z250, Filtek Supreme, and Premise. Specimens were immersed for 2 min daily, up to 6 months, in six storage solutions (n=7 per material for each solution): distilled water, Powerade, Gatorade, X-IR, Burn, and Red Bull. Surface hardness was measured at baseline, after 1 week, 1 month, and 6 months. Data were analyzed statistically using repeated measures ANOVA followed by the Bonferroni test for multiple comparisons (α=0.05). Surface hardness of the restorative materials was significantly affected by both immersion solution and immersion period (p<0.001). All tested solutions induced significant reduction in surface hardness of the restorative materials over a 6-month immersion period.

Compression set in gas-blown condensation-cured polysiloxane elastomers

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

Patel, Mogon; Chinn, Sarah; Maxwell, Robert S.

2010-12-01

Accelerated thermal ageing studies on foamed condensation cured polysiloxane materials have been performed in support of life assessment and material replacement programmes. Two different types of filled hydrogen-blown and condensation cured polysiloxane foams were tested; commercial (RTV S5370), and an in-house formulated polysiloxane elastomer (Silfoam). Compression set properties were investigated using Thermomechanical (TMA) studies and compared against two separate longer term ageing trials carried out in air and in dry inert gas atmospheres using compression jigs. Isotherms measured from these studies were assessed using time-temperature (T/t) superposition. Acceleration factors were determined and fitted to Arrhenius kinetics. For both materials, themore » thermo-mechanical results were found to closely follow the longer term accelerated ageing trials. Comparison of the accelerated ageing data in dry nitrogen atmospheres against field trial results showed the accelerated ageing trends over predict, however the comparison is difficult as the field data suffer from significant component to component variability. Of the long term ageing trials reported here, those carried out in air deviate more significantly from field trials data compared to those carried out in dry nitrogen atmospheres. For field return samples, there is evidence for residual post-curing reactions influencing mechanical performance, which would accelerate compression set. Multiple quantum-NMR studies suggest that compression set is not associated with significant changes in net crosslink density, but that some degree of network rearrangement has occurred due to viscoelastic relaxation as well as bond breaking and forming processes, with possible post-curing reactions at early times.« less

Reduced short-term memory capacity in Alzheimer's disease: the role of phonological, lexical, and semantic processing.

PubMed

Caza, Nicole; Belleville, Sylvie

2008-05-01

Individuals with Alzheimer's disease (AD) are often reported to have reduced verbal short-term memory capacity, typically attributed to their attention/executive deficits. However, these individuals also tend to show progressive impairment of semantic, lexical, and phonological processing which may underlie their low short-term memory capacity. The goals of this study were to assess the contribution of each level of representation (phonological, lexical, and semantic) to immediate serial recall performance in 18 individuals with AD, and to examine how these linguistic effects on short-term memory were modulated by their reduced capacity to manipulate information in short-term memory associated with executive dysfunction. Results showed that individuals with AD had difficulty recalling items that relied on phonological representations, which led to increased lexicality effects relative to the control group. This finding suggests that patients have a greater reliance on lexical/semantic information than controls, possibly to make up for deficits in retention and processing of phonological material. This lexical/semantic effect was not found to be significantly correlated with patients' capacity to manipulate verbal material in short-term memory, indicating that language processing and executive deficits may independently contribute to reducing verbal short-term memory capacity in AD.

Environmental effects on composites for aircraft

NASA Technical Reports Server (NTRS)

Pride, R. A.

1978-01-01

A number of ongoing, long-term environmental effects programs for composite materials are evaluated. The flight service experience was evaluated for 142 composite aircraft components after more than 5 years and 1 million successful component flight hours. Ground-based outdoor exposures of composite material coupons after 3 years of exposure at 5 sites have reached equilibrium levels of moisture pickup which are predictable. Solar ultraviolet-induced material loss is discussed for these same exposures. No significant degradation was observed in residual strength for either stressed or unstressed specimens, or for exposures to aviation fuels and fluids.

Biomolecular Materials. Report of the January 13-15, 2002 Workshop

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

Alper, M. D.; Stupp, S. I.

2002-01-15

Twenty-two scientists from around the nation and the world met to discuss the way that the molecules, structures, processes and concepts of the biological world could be used or mimicked in designing novel materials, processes or devices of potential practical significance. The emphasis was on basic research, although the long-term goal is, in addition to increased knowledge, the development of applications to further the mission of the Department of Energy.

Assessment of Heat Hazard during the Polymerization of Selected Light-Sensitive Dental Materials.

PubMed

Janeczek, Maciej; Herman, Katarzyna; Fita, Katarzyna; Dudek, Krzysztof; Kowalczyk-Zając, Małgorzata; Czajczyńska-Waszkiewicz, Agnieszka; Piesiak-Pańczyszyn, Dagmara; Kosior, Piotr; Dobrzyński, Maciej

2016-01-01

Introduction. Polymerization of light-cured dental materials used for restoration of hard tooth tissue may lead to an increase in temperature that may have negative consequence for pulp vitality. Aim. The aim of this study was to determine maximum temperatures reached during the polymerization of selected dental materials, as well as the time that is needed for samples of sizes similar to those used in clinical practice to reach these temperatures. Materials and Methods. The study involved four composite restorative materials, one lining material and a dentine bonding agent. The polymerization was conducted with the use of a diode light-curing unit. The measurements of the external surface temperature of the samples were carried out using the Thermovision®550 thermal camera. Results. The examined materials significantly differed in terms of the maximum temperatures values they reached, as well as the time required for reaching the temperatures. A statistically significant positive correlation of the maximum temperature and the sample weight was observed. Conclusions. In clinical practice, it is crucial to bear in mind the risk of thermal damage involved in the application of light-cured materials. It can be reduced by using thin increments of composite materials.

Evaluating psychosocial and behavioral mechanisms of change in a tailored communication intervention.

PubMed

Elder, John P; Ayala, Guadalupe X; Slymen, Donald J; Arredondo, Elva M; Campbell, Nadia R

2009-04-01

This study examined the impact of a tailored nutrition intervention at 3 and 6 months postintervention. In all, 357 Latinas were randomly assigned to one of three conditions: (1) a control condition comprised of previously developed Spanish language targeted materials, (2) tailored print materials, or (3) tailored print materials accompanied by personalized dietary counseling via lay heath advisors (promotoras). At 6 months postintervention, significant group by time interactions were observed on the dietary behavioral strategies scales. The promotora condition resulted in significant behavior change initially; however, receipt of tailored and control materials was instrumental in continued behavior change after intervention activities had ceased. Group main effects suggested that the promotora condition was superior at reducing barriers and improving family interactions supporting healthy behaviors. The promotora model is an effective method for changing important dietary behaviors and psychosocial determinants, but longer term behavior change is achievable with less expensive intervention methods.

Applicability of Long Duration Exposure Facility environmental effects data to the design of Space Station Freedom electrical power system

NASA Technical Reports Server (NTRS)

Christie, Robert J.; Lu, Cheng-Yi; Aronoff, Irene

1992-01-01

Data defining space environmental effects on the Long Duration Exposure Facility (LDEF) are examined in terms of the design of the electrical power system (EPS) of the Space Station Freedom (SSF). The significant effects of long-term exposure to space are identified with respect to the performance of the LDEF's materials, components, and systems. A total of 57 experiments were conducted on the LDEF yielding information regarding coatings, thermal systems, electronics, optics, and power systems. The resulting database is analyzed in terms of the specifications of the SSF EPS materials and subsystems and is found to be valuable in the design of control and protection features. Specific applications are listed for findings regarding the thermal environment, atomic oxygen, UV and ionizing radiation, debris, and contamination. The LDEF data are shown to have a considerable number of applications to the design and planning of the SSF and its EPS.

Complete Report on the Development of Welding Parameters for Irradiated Materials

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

Frederick, Greg; Sutton, Benjamin J.; Tatman, Jonathan K.

The advanced welding facility at the Radiochemical Engineering Development Center of Oak Ridge National Laboratory, which was conceived to enable research and development of weld repair techniques for nuclear power plant life extension, is now operational. The development of the facility and its advanced welding capabilities, along with the model materials for initial welding trials, were funded jointly by the U.S. Department of Energy, Office of Nuclear Energy, Light Water Reactor Sustainability Program, the Electric Power Research Institute, Long Term Operations Program and the Welding and Repair Technology Center, with additional support from Oak Ridge National Laboratory. Welding of irradiatedmore » materials was initiated on November 17, 2017, which marked a significant step in the development of the facility and the beginning of extensive welding research and development campaigns on irradiated materials that will eventually produce validated techniques and guidelines for weld repair activities carried out to extend the operational lifetimes of nuclear power plants beyond 60 years. This report summarizes the final steps that were required to complete weld process development, initial irradiated materials welding activities, near-term plans for irradiated materials welding, and plans for post-weld analyses that will be carried out to assess the ability of the advanced welding processes to make repairs on irradiated materials.« less

Comparative three-dimensional analysis of initial biofilm formation on three orthodontic bracket materials.

PubMed

Dittmer, Marc Philipp; Hellemann, Carolina Fuchslocher; Grade, Sebastian; Heuer, Wieland; Stiesch, Meike; Schwestka-Polly, Rainer; Demling, Anton Phillip

2015-04-10

The purpose of the present study was to investigate and compare early biofilm formation on biomaterials, which are being used in contemporary fixed orthodontic treatment. This study comprised 10 healthy volunteers (5 females and 5 males) with a mean age of 27.3 +-3.7 years. Three slabs of different orthodontic materials (stainless steel, gold and ceramic) were placed in randomized order on a splint in the mandibular molar region. Splints were inserted intraorally for 48 h. Then the slabs were removed from the splints and the biofilms were stained with a two color fluorescence assay for bacterial viability (LIVE/DEAD BacLight-Bacterial Viability Kit 7012, Invitrogen, Mount Waverley, Australia). The quantitative biofilm formation was analyzed by using confocal laser scanning microscopy (CLSM). The biofilm coverage was 32.7 ± 37.7% on stainless steel surfaces, 59.5 ± 40.0% on gold surfaces and 56.8 ± 43.6% on ceramic surfaces. Statistical analysis showed significant differences in biofilm coverage between the tested materials (p=0.033). The Wilcoxon test demonstrated significantly lower biofilm coverage on steel compared to gold (p=0.011). Biofilm height on stainless steel surfaces was 4.0 ± 7.3 μm, on gold surfaces 6.0 ± 6.6 μm and on ceramic 6.5 ± 6.0 μm. The Friedman test revealed no significant differences between the tested materials (p=0.150). Pairwise comparison demonstrated significant differences between stainless steel and gold (p=0.047). Our results indicate that initial biofilm formation seemed to be less on stainless steel surfaces compared with other traditional materials in a short-term observation. Future studies should examine whether there is a difference in long-term biofilm accumulation between stainless steel, gold and ceramic brackets.

Constitutive Modeling of Crosslinked Nanotube Materials

NASA Technical Reports Server (NTRS)

Odegard, G. M.; Frankland, S. J. V.; Herzog, M. N.; Gates, T. S.; Fay, C. C.

2004-01-01

A non-linear, continuum-based constitutive model is developed for carbon nanotube materials in which bundles of aligned carbon nanotubes have varying amounts of crosslinks between the nanotubes. The model accounts for the non-linear elastic constitutive behavior of the material in terms of strain, and is developed using a thermodynamic energy approach. The model is used to examine the effect of the crosslinking on the overall mechanical properties of variations of the crosslinked carbon nanotube material with varying degrees of crosslinking. It is shown that the presence of the crosslinks has significant effects on the mechanical properties of the carbon nanotube materials. An increase in the transverse shear properties is observed when the nanotubes are crosslinked. However, this increase is accompanied by a decrease in axial mechanical properties of the nanotube material upon crosslinking.

Mechanical properties and microstructure of long term thermal aged WWER 440 RPV steel

NASA Astrophysics Data System (ADS)

Kolluri, M.; Kryukov, A.; Magielsen, A. J.; Hähner, P.; Petrosyan, V.; Sevikyan, G.; Szaraz, Z.

2017-04-01

The integrity assessment of the Reactor Pressure Vessel (RPV) is essential for the safe and Long Term Operation (LTO) of a Nuclear Power Plant (NPP). Hardening and embrittlement of RPV caused by neutron irradiation and thermal ageing are main reasons for mechanical properties degradation during the operation of an NPP. The thermal ageing-induced degradation of RPV steels becomes more significant with extended operational lives of NPPs. Consequently, the evaluation of thermal ageing effects is important for the structural integrity assessments required for the lifetime extension of NPPs. As a part of NRG's research programme on Structural Materials for safe-LTO of Light Water Reactor (LWR) RPVs, WWER-440 surveillance specimens, which have been thermal aged for 27 years (∼200,000 h) at 290 °C in a surveillance channel of Armenian-NPP, are investigated. Results from the mechanical and microstructural examination of these thermal aged specimens are presented in this article. The results indicate the absence of significant long term thermal ageing effect of 15Cr2MoV-A steel. No age hardening was detected in aged tensile specimens compared with the as-received condition. There is no difference between the impact properties of as-received and thermal aged weld metals. The upper shelf energy of the aged steel remains the same as for the as-received material at a rather high level of about 120 J. The T41 value did not change and was found to be about 10 °C. The microstructure of thermal aged weld, consisting carbides, carbonitrides and manganese-silicon inclusions, did not change significantly compared to as-received state. Grain-boundary segregation of phosphorus in long term aged weld is not significant either which has been confirmed by the absence of intergranular fracture increase in the weld. Negligible hardening and embrittlement observed after such long term thermal ageing is attributed to the optimum chemical composition of 15Cr2MoV-A for high thermal stability.

Content, format, gender and grade level differences in elementary students' ability to read science materials as measured by the cloze procedure

NASA Astrophysics Data System (ADS)

Williams, Richard L.; Yore, Larry D.

Present instructional trends in science indicate a need to reexamine a traditional concern in science education: the readability of science textbooks. An area of reading research not well documented is the effect of color, visuals, and page layout on readability of science materials. Using the cloze readability method, the present study explored the relationships between page format, grade level, sex, content, and elementary school students ability to read science material. Significant relationships were found between cloze scores and both grade level and content, and there was a significant interaction effect between grade and sex in favor of older males. No significant relationships could be attributed to page format and sex. In the area of science content, biological materials were most difficult in terms of readability followed by earth science and physical science. Grade level data indicated that grade five materials were more difficult for that level than either grade four or grade six materials were for students at each respective level. In eight of nine cases, the science text materials would be classified at or near the frustration level of readability. The implications for textbook writers and publishers are that science reading materials need to be produced with greater attention to readability and known design principles regarding visual supplements. The implication for teachers is that students need direct instruction in using visual materials to increase their learning from text material. Present visual materials appear to neither help nor hinder the student to gain information from text material.

Third Conference on Fibrous Composites in Flight Vehicle Design, part 1

NASA Technical Reports Server (NTRS)

1976-01-01

The use of fibrous composite materials in the design of aircraft and space vehicle structures and their impact on future vehicle systems are discussed. The topics covered include: flight test work on composite components, design concepts and hardware, specialized applications, operational experience, certification and design criteria. Contributions to the design technology base include data concerning material properties, design procedures, environmental exposure effects, manufacturing procedures, and flight service reliability. By including composites as baseline design materials, significant payoffs are expected in terms of reduced structural weight fractions, longer structural life, reduced fuel consumption, reduced structural complexity, and reduced manufacturing cost.

LDEF Materials Results for Spacecraft Applications

NASA Technical Reports Server (NTRS)

Whitaker, Ann F. (Compiler); Gregory, John (Compiler)

1993-01-01

These proceedings describe the application of LDEF data to spacecraft and payload design, and emphasize where space environmental effects on materials research and development is needed as defined by LDEF data. The LDEF six years of exposure of materials has proven to be by far the most comprehensive source of information ever obtained on the long-term performance of materials in the space environment. The conference provided a forum for materials scientists and engineers to review and critically assess the LDEF results from the standpoint of their relevance, significance, and impact on spacecraft design practice. The impact of the LDEF findings on materials selection and qualification, and the needs and plans for further study, were addressed from several perspectives. Many timely and needed changes and modifications in external spacecraft materials selection have occurred as a result of LDEF investigations.

Understanding Biogeochemical Transformations Of Trace Elements In Multi Metal-Rich Geomaterials Under Stimulated Redox Conditions

EPA Science Inventory

Natural and anthropogenic influences on hydrological conditions can induce periodic or long-term reduced conditions in geologic materials. Such conditions can cause significant impacts on biogeochemical processes of trace elements in subsurface or near surface environments. The...

Absorbable synthetic versus catgut suture material for perineal repair

PubMed Central

Kettle, Christine

2014-01-01

Background Approximately 70% of women will experience some degree of perineal trauma following vaginal delivery and will require stitches. This may result in perineal pain and superficial dyspareunia. Objectives The objective of this review was to assess the effects of absorbable synthetic suture material as compared with catgut on the amount of short and long term pain experienced by mothers following perineal repair. Search strategy We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register. Selection criteria Randomised trials comparing absorbable synthetic (polyglycolic acid and polyglactin) with plain or chromic catgut suture for perineal repair in mothers after vaginal delivery. Data collection and analysis Trial quality was assessed independently by two reviewers. Data were extracted by one reviewer and checked by the second reviewer. Main results Eight trials were included. Compared with catgut, the polyglycolic acid and polyglactin groups were associated with less pain in first three days (odds ratio 0.62, 95% confidence interval 0.54 to 0.71). There was also less need for analgesia (odds ratio 0.63, 95% confidence interval 0.52 to 0.77) and less suture dehiscence (odds ratio 0.45, 95% confidence interval 0.29 to 0.70). There was no significant difference in long term pain (odds ratio 0.81, 95% confidence interval 0.61 to 1.08). Removal of suture material was significantly more common in the polyglycolic acid and polyglactin groups (odds ratio 2.01, 95% confidence interval 1.56 to 2.58). There was no difference in the amount of dyspareunia experienced by women. Authors’ conclusions Absorbable synthetic suture material (in the form of polyglycolic acid and polyglactin sutures) for perineal repair following childbirth appears to decrease women’s experience of short-term pain. The length of time taken for the synthetic material to be absorbed is of concern. A trial addressing the use of polyglactin has recently been completed and this has been included in this updated review. PMID:10796081

Influence of long-term in vivo exposure, debris accumulation and archwire material on friction force among different types of brackets and archwires couples.

PubMed

Mezeg, Uroš; Primožic, Jasmina

2017-11-30

The aim was to assess the influence of long-term in vivo exposure, debris accumulation and archwire material on static and kinetic friction force among different types of brackets and archwires couples. Friction testing was performed among four lower incisors' brackets, conventional and self-ligating (SL), coupled with either nickel-titanium or stainless steel archwires, as-received and in vivo exposed in 18 subjects. The friction testing was performed for a sliding distance of 14 mm at a speed of 10 mm/min, with a starting force of 0.2 N. Wear and quantitative assessment of debris accumulation was performed on pictures of brackets obtained using a scanning electron microscope. Non parametric tests were used for statistical analysis. Only bracket type, but not exposure duration, amount of debris accumulation, archwire material or their manufacturer, was significantly correlated with both static (rho = 0.602, P < 0.001) and kinetic (rho = 0.584, P < 0.001) friction force. Within each bracket type no significant difference was observed between as-received and in vivo exposed brackets for any friction parameter except for the SL brackets in which significantly higher static and kinetic (P = 0.001, at least) friction forces were seen in in vivo exposed SL brackets (164.9 cN and 217.63 cN, respectively) in comparison with as-received SL brackets (19.69 cN and 55.72 cN, respectively). The frictional testing was performed in the dry condition which might have influenced the results. A significant correlation was seen between friction force and bracket type, while treatment duration, amount of debris accumulation, archwire material or their manufacturer was not significantly correlated to it. Nevertheless, higher friction forces were measured among in vivo aged SL brackets in comparison with as-received ones. © The Author 2017. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com

Does long term exposure to radon gas influence the properties of polymeric waterproof materials?

NASA Astrophysics Data System (ADS)

Navratilova Rovenska, Katerina; Jiranek, Martin; Kokes, Pavel; Wasserbauer, Richard; Kacmarikova, Veronika

2014-01-01

The technical state of buildings and the quality of the indoor environment depend on the quality of the waterproofing course and on the properties of the insulating materials that are applied, in particular on their durability, long-term functional reliability and resistance to corrosive effects of the subsoil. Underground water chemistry and soil bacteria are well-known corrosive agents. Our investigations indicate that the ageing process of waterproof materials can be significantly accelerated by alpha particles emitted by radon and radon progenies which are present in soil gas. Materials commonly available on the building market, e.g. LDPE and HDPE of various densities, PVC, TPO (thermoplastic polyolefin), PP (polypropylene) and EPDM were selected for our experimental study. The preliminary results for 3-year exposure to radon gas show a decrease in tensile strength to 60%, elongation to 80% and hardness to 95% for samples based on PE. The diffusion coefficient of radon for samples based on PVC decreased to 20% of the initial value after 1-year exposure to radon and soil bacteria.

Beyond Quarterly Earnings: Preparing the Business Community for Long-term Climate Risks

NASA Astrophysics Data System (ADS)

Carlson, C.; Goldman, G. T.

2014-12-01

The business community stands to be highly impacted by climate change. In both short and long-term timescales, climate change presents material and financial risks to companies in diverse economic sectors. How the private sector accounts for long-term risks while making short-term decisions about operations is a complex challenge. Companies are accountable to shareholders and must report performance to them on a quarterly basis. At the same time, company investors are exposed to long-term climate-related risks and face losses if companies fail to prepare for climate impacts. The US Securities and Exchange Commission (SEC) obligates publicly traded companies to discuss risks that might materially affect their business and since 2010, the agency recommends that companies consider and discuss any significant risks to their business from climate change. Some companies have complied with this guidance and comprehensively analyze potential climate change impacts, yet others fail to consider climate change at all. Such omissions leave companies without plans for addressing future risks and expose investors and the public to potential catastrophic events from climate change impacts. Climate risk projections can inform companies about the vulnerability of their facilities, supply chains, transportation pathways, and other assets. Such projections can help put climate-related risks in terms of material costs for companies and their investors. Focusing on the vulnerability of coastal facilities, we will use climate change impact projections to demonstrate the economic impacts of climate change faced by the private sector. These risks are then compared to company disclosures to the SEC to assess the degree to which companies have considered their vulnerability to climate change. Finally, we will discuss ways that companies can better assess and manage long-term climate risks.

Review on fluoride-releasing restorative materials--fluoride release and uptake characteristics, antibacterial activity and influence on caries formation.

PubMed

Wiegand, Annette; Buchalla, Wolfgang; Attin, Thomas

2007-03-01

The purpose of this article was to review the fluoride release and recharge capabilities, and antibacterial properties, of fluoride-releasing dental restoratives, and discuss the current status concerning the prevention or inhibition of caries development and progression. Information from original scientific full papers or reviews listed in PubMed (search term: fluoride release AND (restorative OR glass-ionomer OR compomer OR polyacid-modified composite resin OR composite OR amalgam)), published from 1980 to 2004, was included in the review. Papers dealing with endodontic or orthodontic topics were not taken into consideration. Clinical studies concerning secondary caries development were only included when performed in split-mouth design with an observation period of at least three years. Fluoride-containing dental materials show clear differences in the fluoride release and uptake characteristics. Short- and long-term fluoride releases from restoratives are related to their matrices, setting mechanisms and fluoride content and depend on several environmental conditions. Fluoride-releasing materials may act as a fluoride reservoir and may increase the fluoride level in saliva, plaque and dental hard tissues. However, clinical studies exhibited conflicting data as to whether or not these materials significantly prevent or inhibit secondary caries and affect the growth of caries-associated bacteria compared to non-fluoridated restoratives. Fluoride release and uptake characteristics depend on the matrices, fillers and fluoride content as well as on the setting mechanisms and environmental conditions of the restoratives. Fluoride-releasing materials, predominantly glass-ionomers and compomers, did show cariostatic properties and may affect bacterial metabolism under simulated cariogenic conditions in vitro. However, it is not proven by prospective clinical studies whether the incidence of secondary caries can be significantly reduced by the fluoride release of restorative materials.

Long-term room temperature stability of TlBr gamma detectors

NASA Astrophysics Data System (ADS)

Conway, A. M.; Voss, L. F.; Nelson, A. J.; Beck, P. R.; Graff, R. T.; Nikolic, R. J.; Payne, S. A.; Kim, H.; Cirignano, L. J.; Shah, K.

2011-09-01

TlBr is a material of interest for use in room temperature gamma ray detector applications due to is wide bandgap 2.7 eV and high average atomic number (Tl 81, Br 35). Researchers have achieved energy resolutions of 1.3 % at 662 keV, demonstrating the potential of this material system. However, these detectors are known to polarize using conventional configurations, limiting their use. Continued improvement of room temperature, high-resolution gamma ray detectors based on TlBr requires further understanding of the degradation mechanisms. While high quality material is a critical starting point for excellent detector performance, we show that the room temperature stability of planar TlBr gamma spectrometers can be significantly enhanced by treatment with both hydrofluoric and hydrochloric acid. By incorporating F or Cl into the surface of TlBr, current instabilities are eliminated and the longer term current of the detectors remains unchanged. 241Am spectra are also shown to be more stable for extended periods; detectors have been held at 2000 V/cm for 52 days with less than 10% degradation in peak centroid position. In addition, evidence for the long term degradation mechanism being related to the contact metal is presented.

Density and composition of microorganisms during long-term (418 day) growth of potato using biologically reclaimed nutrients from inedible plant biomass

NASA Technical Reports Server (NTRS)

Garland, J. L.; Cook, K. L.; Johnson, M.; Sumner, R.; Fields, N.; Sager, J. C. (Principal Investigator)

1997-01-01

A study evaluating alternative methods for long term operation of biomass production systems was recently completed at the Kennedy Space Center (KSC). The 418-day study evaluated repeated batch versus mixed-aged production of potato grown on either standard 1/2-strength Hoagland's nutrient solution or solutions including nutrients recycled from inedible plant material. The long term effects of closure and recycling on microbial dynamics were evaluated by monitoring the microbial communities associated with various habitats within the plant growth system (i.e., plant roots, nutrient solution, biofilms within the hydroponic systems, atmosphere, and atmospheric condensate). Plate count methods were used to enumerate and characterize microorganisms. Microscopic staining methods were used to estunate total cell densities. The primary finding was that the density and composition of microbial communities associated with controlled environmental plant growth systems are stable during long term operation. Continuous production resulted in slightly greater stability. Nutrient recycling, despite the addition of soluble organic material from the waste processing system, did not significantly increase microbial density in any of the habitats.

Density and composition of microorganisms during long-term (418 day) growth of potato using biologically reclaimed nutrients from inedible plant biomass

NASA Astrophysics Data System (ADS)

Garland, J. L.; Cook, K. L.; Johnson, M.; Sumner, R.; Fields, N.

1997-01-01

A study evaluating alternative methods for long term operation of biomass production systems was recently completed at the Kennedy Space Center (KSC). The 418-day study evaluated repeated batch versus mixed-aged production of potato grown on either standard 1/2-strength Hoagland's nutrient solution or solutions including nutrients recycled from inedible plant material. The long term effects of closure and recycling on microbial dynamics were evaluated by monitoring the microbial communities associated with various habitats within the plant growth system (i.e., plant roots, nutrient solution, biofilms within the hydroponic systems, atmosphere, and atmospheric condensate). Plate count methods were used to enumerate and characterize microorganisms. Microscopic staining methods were used to estimate total cell densities. The primary finding was that the density and composition of microbial communities associated with controlled environmental plant growth systems are stable during long term operation. Continuous production resulted in slightly greater stability. Nutrient recycling, despite the addition of soluble organic material from the waste processing system, did not significantly increase microbial density in any of the habitats.

Density and composition of microorganisms during long-term (418 day) growth of potato using biologically reclaimed nutrients from inedible plant biomass

NASA Astrophysics Data System (ADS)

1997-01-01

A study evaluating alternative methods for long term operation of biomass production systems was recently completed at the Kennedy Space Center (KSC). The 418-day study evaluated repeated batch versus mixed-aged production of potato grown on either standard 12-strength Hoagland's nutrient solution or solutions including nutrients recycled from inedible plant material. The long term effects of closure and recycling on microbial dynamics were evaluated by monitoring the microbial communities associated with various habitats within the plant growth system (i.e., plant roots, nutrient solution, biofilms within the hydroponic systems, atmosphere, and atmospheric condensate). Plate count methods were used to enumerate and characterize microorganisms. Microscopic staining methods were used to estimate total cell densities. The primary finding was that the density and composition of microbial communities associated with controlled environmental plant growth systems are stable during long term operation. Continuous production resulted in slightly greater stability. Nutrient recycling, despite the addition of soluble organic material from the waste processing system, did not significantly increase microbial density in any of the habitats.

Solar Sail Material Performance Property Response to Space Environmental Effects

NASA Technical Reports Server (NTRS)

Edwards, David L.; Semmel, Charles; Hovater, Mary; Nehls, Mary; Gray, Perry; Hubbs, Whitney; Wertz, George

2004-01-01

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) continues research into the utilization of photonic materials for spacecraft propulsion. Spacecraft propulsion, using photonic materials, will be achieved using a solar sail. A solar sail operates on the principle that photons, originating from the sun, impart pressure to the sail and therefore provide a source for spacecraft propulsion. The pressure imparted to a solar sail can be increased, up to a factor of two, if the sun-facing surface is perfectly reflective. Therefore, these solar sails are generally composed of a highly reflective metallic sun-facing layer, a thin polymeric substrate and occasionally a highly emissive back surface. Near term solar sail propelled science missions are targeting the Lagrange point 1 (Ll) as well as locations sunward of L1 as destinations. These near term missions include the Solar Polar Imager and the L1 Diamond. The Environmental Effects Group at NASA s Marshall Space Flight Center (MSFC) continues to actively characterize solar sail material in preparation for these near term solar sail missions. Previous investigations indicated that space environmental effects on sail material thermo-optical properties were minimal and would not significantly affect the propulsion efficiency of the sail. These investigations also indicated that the sail material mechanical stability degrades with increasing radiation exposure. This paper will further quantify the effect of space environmental exposure on the mechanical properties of candidate sail materials. Candidate sail materials for these missions include Aluminum coated Mylar[TM], Teonex[TM], and CPl (Colorless Polyimide). These materials were subjected to uniform radiation doses of electrons and protons in individual exposures sequences. Dose values ranged from 100 Mrads to over 5 Grads. The engineering performance property responses of thermo-optical and mechanical properties were characterized. The contribution of Near Ultraviolet (NUV) radiation combined with electron and proton radiation was also investigated.

Space Environmental Effects on Candidate Solar Sail Materials

NASA Technical Reports Server (NTRS)

Edwards, David L.; Nehls, Mary; Semmel, Charles; Hovater, Mary; Gray, Perry; Hubbs, Whitney; Wertz, George

2004-01-01

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) continues research into the utilization of photonic materials for spacecraft propulsion. Spacecraft propulsion, using photonic materials, will be achieved using a solar sail. A solar sail operates on the principle that photons, originating from the sun, impart pressure to the sail and therefore provide a source for spacecraft propulsion. The pressure imparted ot a solar sail can be increased, up to a factor of two, if the sun-facing surface is perfectly reflective. Therefore, these solar sails are generally composed of a highly reflective metallic sun-facing layer, a thin polymeric substrate and occasionally a highly emissive back surface. Near term solar sail propelled science missions are targeting the Lagrange point 1 (L1) as well as locations sunward of L1 as destinations. These near term missions include the Solar Polar Imager and the L1 Diamond. The Environmental Effects Group at NASA's Marshall Space Flight Center (MSFC) continues to actively characterize solar sail material in preparation for these near term solar sail missions. Previous investigations indicated that space environmental effects on sail material thermo-optical properties were minimal and would not significantly affect the propulsion efficiency of the sail. These investigations also indicated that the sail material mechanical stability degrades with increasing radiation exposure. This paper will further quantify the effect of space environmental exposure on the mechanical properties of candidate sail materials. Candidate sail materials for these missions include Aluminum coated Mylar, Teonex, and CP1 (Colorless Polyimide). These materials were subjected to uniform radiation doses of electrons and protons in individual exposures sequences. Dose values ranged from 100 Mrads to over 5 Grads. The engineering performance property responses of thermo-optical and mechanical properties were characterized. The contribution of Near Ultraviolet (NUV) radiation combined with electron and proton radiation was also investigated.

Solar Sail Material Performance Property Response to Space Environmental Effects

NASA Technical Reports Server (NTRS)

Edwards, David L.; Semmel, Charles; Hovater, Mary; Nehls, Mary; Gray, Perry; Hubbs, Whitney; Wertz, George

2004-01-01

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) continues research into the utilization of photonic materials for spacecraft propulsion. Spacecraft propulsion, using photonic materials, will be achieved using a solar sail. A solar sail operates on the principle that photons, originating from the sun, impart pressure to the sail and therefore provide a source for spacecraft propulsion. The pressure imparted to a solar sail can be increased, up to a factor of two if the sun-facing surface is perfectly reflective. Therefore, these solar sails are generally composed of a highly reflective metallic sun-facing layer, a thin polymeric substrate and occasionally a highly emissive back surface. Near term solar sail propelled science missions are targeting the Lagrange point 1 (L1) as well as locations sunward of L1 as destinations. These near term missions include the Solar Polar Imager' and the L1 Diamond '. The Environmental Effects Group at NASA's Marshall Space Fliglit Center (MSFC) continues to actively characterize solar sail material in preparation for these near term solar sail missions. Previous investigations indicated that space environmental effects on sail material thermo-optical properties were minimal and would not significantly affect the propulsion efficiency of the sail3-'. These investigations also indicated that the sail material mechanical stability degrades with increasing radiation exposure. This paper will further quantify the effect of space environmental exposure on the mechanical properties of candidate sail materials. Candidate sail materials for these missions include Aluminum coated Mylar TM, Teonexm, and CP1 (Colorless Polyimide). These materials were subjected to uniform radiation doses of electrons and protons in individual exposures sequences. Dose values ranged from 100 Mrads to over 5 Grads. The engineering performance property responses of thermo-optical and mechanical properties were characterized. The contribution of Near Ultraviolet (NUV) radiation combined with electron and proton radiation was also investigated. Conclusions will be presented providing a gauge of measure for engineering performance stability for sails operating in the L1 space environment.

Long-term pavement performance project laboratory materials testing and handling guide

DOT National Transportation Integrated Search

2007-09-01

The Long Term Pavement Performance (LTPP) Laboratory Material Testing Guide was originally prepared for laboratory material handling and testing of material specimens and samples of asphalt materials, portland cement concrete, aggregates, and soils u...

FREUD, JUNG AND BOAS: THE PSYCHOANALYTIC ENGAGEMENT WITH ANTHROPOLOGY REVISITED.

PubMed

Kenny, Robert

2015-06-20

Sigmund Freud's and C. G. Jung's turn to evolutionist anthropological material after 1909 is usually seen as a logical progression of their long-term interest in such material. It is also seen that they used this material ignorant of the significant challenges to the evolutionist paradigm underpinning such material, in particular the challenges led by Franz Boas. This paper argues otherwise: that both psychologists' turnings to such material was a new development, that neither had shown great interest in such material before 1909, and that their turnings to such material, far from being taken in ignorance of the challenges to evolutionist anthropology, were engagements with those challenges, because the evolutionist paradigm lay at the base of psychoanalysis. It argues that it is no coincidence that this engagement occurred after their return from America in 1909, where they had come into first-hand contact with the challenges of Franz Boas.

Freud, Jung and Boas: the psychoanalytic engagement with anthropology revisited

PubMed Central

Kenny, Robert

2015-01-01

Sigmund Freud's and C. G. Jung's turn to evolutionist anthropological material after 1909 is usually seen as a logical progression of their long-term interest in such material. It is also seen that they used this material ignorant of the significant challenges to the evolutionist paradigm underpinning such material, in particular the challenges led by Franz Boas. This paper argues otherwise: that both psychologists' turnings to such material was a new development, that neither had shown great interest in such material before 1909, and that their turnings to such material, far from being taken in ignorance of the challenges to evolutionist anthropology, were engagements with those challenges, because the evolutionist paradigm lay at the base of psychoanalysis. It argues that it is no coincidence that this engagement occurred after their return from America in 1909, where they had come into first-hand contact with the challenges of Franz Boas. PMID:26665301

Effects of physical aging on long-term behavior of composites

NASA Technical Reports Server (NTRS)

Brinson, L. Catherine

1993-01-01

The HSCT plane, envisioned to have a lifetime of over 60,000 flight hours and to travel at speeds in excess of Mach 2, is the source of intensive study at NASA. In particular, polymer matrix composites are being strongly considered for use in primary and secondary structures due to their high strength to weight ratio and the options of property tailoring. However, an added difficulty in the use of polymer based materials is that their properties change significantly over time, especially at the elevated temperatures that will be experienced during flight, and prediction of properties based on irregular thermal and mechanical loading is extremely difficult. This study focused on one aspect of long-term polymer composite behavior: physical aging. When a polymer is cooled to below its glass transition temperature, the material is not in thermodynamic equilibrium and the free volume and enthalpy evolve over time to approach their equilibrium values. During this time, the mechanical properties change significantly and this change is termed physical aging. This work begins with a review of the concepts of physical aging on a pure polymer system. The effective time theory, which can be used to predict long term behavior based on short term data, is mathematically formalized. The effects of aging to equilibrium are proven and discussed. The theory developed for polymers is then applied first to a unidirectional composite, then to a general laminate. Comparison to experimental data is excellent. It is shown that the effects of aging on the long-term properties of composites can be counter-intuitive, stressing the importance of the development and use of a predictive theory to analyze structures.

The Uses of Globalization in the (Shifting) Landscape of Educational Studies

ERIC Educational Resources Information Center

Tarc, Paul

2012-01-01

The term "globalization" does more than represent a set of material (and ideological) processes that have impacts on education and schooling. Additionally, "globalization" operates as a conceptual lens or set of interventions, which is significantly impacting academic discourses in Education and in other disciplines. Not only…

A Photonic Basis for Deriving Nonlinear Optical Response

ERIC Educational Resources Information Center

Andrews, David L.; Bradshaw, David S.

2009-01-01

Nonlinear optics is generally first presented as an extension of conventional optics. Typically the subject is introduced with reference to a classical oscillatory electric polarization, accommodating correction terms that become significant at high intensities. The material parameters that quantify the extent of the nonlinear response are cast as…

A Comparison of implant impression precision: Different materials and techniques

PubMed Central

Tabesh, Mahtab; Alikhasi, Marzieh

2018-01-01

Background Precision of implant impressions is a prerequisite for long-term success of implant supported prostheses. Impression materials and impression techniques are two important factors that impression precision relies on. Material and Methods A model of edentulous maxilla containing four implants inserted by All-on-4 guide was constructed. Seventy two impressions using polyether (PE), polyvinyl siloxane (PVS), and vinyl siloxanether (VSE) materials with direct and indirect techniques were made (n=12). Coordinates of implants in casts were measured using coordinate measuring machine (CMM). Data were analyzed with ANOVA; t-test and Tukey test were used for post hoc. Results With two-way ANOVA, mean values of linear displacements of implants were significantly different among materials and techniques. One-way ANOVA and Tukey showed significant difference between PE and VSE (P=0.019), PE and PVS (P=0.002) in direct technique, and between PVS and PE (P<0.001), PVS and VSE (P<0.001) in indirect technique. One-way ANOVA and t-test showed significant difference between the two techniques in PVS groups (P<0.001) and in PE groups (P=0.02). Two-way ANOVA showed mean values of rotational displacement of implants were significantly different among materials. One-way ANOVA and Tukey test showed significant difference between PVS and PE (P=0.001) and between PVS and VSE (P=0.012) in indirect groups. Conclusions On the basis of the results, when deciding on the material to make an impression of implants, PE is recommended for direct technique while PE and VSE are recommended for indirect technique. Recommended technique for VSE is either direct or indirect; and for PE and PVS is direct. Key words:Polyvinyl siloxane, polyether, vinyl siloxanether, direct technique, indirect technique, All-on-4, coordinate measuring machine. PMID:29670733

Evaluating the Quality, Accuracy, and Readability of Online Resources Pertaining to Hallux Valgus.

PubMed

Tartaglione, Jason P; Rosenbaum, Andrew J; Abousayed, Mostafa; Hushmendy, Shazaan F; DiPreta, John A

2016-02-01

The Internet is one of the most widely utilized resources for health-related information. Evaluation of the medical literature suggests that the quality and accuracy of these resources are poor and written at inappropriately high reading levels. The purpose of our study was to evaluate the quality, accuracy, and readability of online resources pertaining to hallux valgus. Two search terms ("hallux valgus" and "bunion") were entered into Google, Yahoo, and Bing. With the use of scoring criteria specific to hallux valgus, the quality and accuracy of online information related to hallux valgus was evaluated by 3 reviewers. The Flesch-Kincaid score was used to determine readability. Statistical analysis was performed with t tests and significance was determined by P values <.05. Sixty-two unique websites were evaluated. Quality was significantly higher with use of the search term "bunion" as compared to "hallux valgus" (P = .045). Quality and accuracy were significantly higher in resources authored by physicians as compared to nonphysicians (quality, P = .04; accuracy, P < .001) and websites without commercial bias (quality, P = .038; accuracy, P = .011). However, the reading level was significantly more advanced for websites authored by physicians (P = .035). Websites written above an eighth-grade reading level were significantly more accurate than those written at or below an eighth-grade reading level (P = .032). The overall quality of online information related to hallux valgus is poor and written at inappropriate reading levels. Furthermore, the search term used, authorship, and presence of commercial bias influence the value of these materials. It is important for orthopaedic surgeons to become familiar with patient education materials, so that appropriate recommendations can be made regarding valuable resources. Level IV. © 2015 The Author(s).

Improving comprehension and recall of information for an HIV vaccine trial among women at risk for HIV: reading level simplification and inclusion of pictures to illustrate key concepts.

PubMed

Murphy, D A; O'Keefe, Z H; Kaufman, A H

1999-10-01

A simplified version of the prototype HIV vaccine material was developed through (a) reducing reading grade level, (b) restructuring of the organization and categorization of the material, (c) adding pictures designed to emphasize key concepts, and (d) obtaining feedback on the simplified version through focus groups with the target population. Low-income women at risk for HIV (N = 141) recruited from a primary care clinic were randomly assigned to be presented the standard or the simplified version. There were no significant differences between the groups in terms of education or Vocabulary, Block Design, and Passage Comprehension scores. Women who received the simplified version had significantly higher comprehension scores immediately following presentation of the material than did women who received the standard version and were also significantly more likely to recall study benefits and risks. These findings were maintained at 3-month follow-up. Implications for informed consent are discussed.

Chemical formation of soft metal electrodes for flexible and wearable electronics.

PubMed

Wang, Dongrui; Zhang, Yaokang; Lu, Xi; Ma, Zhijun; Xie, Chuan; Zheng, Zijian

2018-06-18

Flexible and wearable electronics is one major technology after smartphones. It shows remarkable application potential in displays and informatics, robotics, sports, energy harvesting and storage, and medicine. As an indispensable part and the cornerstone of these devices, soft metal electrodes (SMEs) are of great significance. Compared with conventional physical processes such as vacuum thermal deposition and sputtering, chemical approaches for preparing SMEs show significant advantages in terms of scalability, low-cost, and compatibility with the soft materials and substrates used for the devices. This review article provides a detailed overview on how to chemically fabricate SMEs, including the material preparation, fabrication technologies, methods to characterize their key properties, and representative studies on different wearable applications.

Scattering by rotationally symmetric anisotropic spheres: potential formulation and parametric studies.

PubMed

Qiu, Cheng-Wei; Li, Le-Wei; Yeo, Tat-Soon; Zouhdi, Saïd

2007-02-01

Vector potential formulation and parametric studies of electromagnetic scattering problems of a sphere characterized by the rotationally symmetric anisotropy are studied. Both epsilon and mu tensors are considered herein, and four elementary parameters are utilized to specify the material properties in the structure. The field representations can be obtained in terms of two potentials, and both TE (TM) modes (with respect to r) inside (outside) the sphere can be derived and expressed in terms of a series of fractional-order (in a real or complex number) Ricatti-Bessel functions. The effects due to either electric anisotropy ratio (Ae=epsilont/epsilonr) or magnetic anisotropy ratio (Am=mut/mur) on the radar cross section (RCS) are considered, and the hybrid effects due to both Ae and Am are also examined extensively. It is found that the material anisotropy affects significantly the scattering behaviors of three-dimensional dielectric objects. For absorbing spheres, however, the Ae or Am no longer plays a significant role as in lossless dielectric spheres and the anisotropic dependence of RCS values is found to be predictable. The hybrid effects of Ae and Am are considered for absorbing spheres as well, but it is found that the RCS can be greatly reduced by controlling the material parameters. Details of the theoretical treatment and numerical results are presented.

3D porous polyurethanes featured by different mechanical properties: Characterization and interaction with skeletal muscle cells.

PubMed

Vannozzi, Lorenzo; Ricotti, Leonardo; Santaniello, Tommaso; Terencio, Tercio; Oropesa-Nunez, Reinier; Canale, Claudio; Borghi, Francesca; Menciassi, Arianna; Lenardi, Cristina; Gerges, Irini

2017-11-01

The fabrication of biomaterials for interaction with muscle cells has attracted significant interest in the last decades. However, 3D porous scaffolds featured by a relatively low stiffness (almost matching the natural muscle one) and highly stable in response to cyclic loadings are not available at present, in this context. This work describes 3D polyurethane-based porous scaffolds featured by different mechanical properties. Biomaterial stiffness was finely tuned by varying the cross-linking degree of the starting foam. Compression tests revealed, for the softest material formulation, stiffness values close to the ones possessed by natural skeletal muscles. The materials were also characterized in terms of local nanoindenting, rheometric properties and long-term stability through cyclic compressions, in a strain range reflecting the contraction extent of natural muscles. Preliminary in vitro tests revealed a preferential adhesion of C2C12 skeletal muscle cells over the softer, rougher and more porous structures. All the material formulations showed low cytotoxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Performance of silvered Teflon thermal control blankets on spacecraft

NASA Astrophysics Data System (ADS)

Pippin, G.; Stuckey, W. K.; Hemminger, C. S.

1993-03-01

Silver-backed fluorinated ethylene propylene Teflon (Ag/FEP) thin film material was used for thermal control in many locations on the Long Duration Exposure Facility (LDEF). The Ag/FEP registered the effects of atomic oxygen, solar ultraviolet radiation, meteoroid and debris impacts, thermal cycling, and contamination. This report summarizes the post-flight condition of the Ag/FEP, compares the results with performance on other spacecraft, and presents lifetime estimates for use under a variety of environmental exposures. Measurements of optical property and mechanical property and surface chemistry changes with exposure conditions, and their significance for design considerations and expected performance lifetimes, are reported for material flown on LDEF. The LDEF based data provides detailed information performance of Ag/FEP under relatively long term exposure in low Earth orbit. Comparison of this data with results from short term shuttle flights, Solar Max, SCATHA, other satellites, and ground based measurements is made to present a comprehensive summary of the use of this material for spacecraft applications.

Comparative abrasive wear resistance and surface analysis of dental resin-based materials

PubMed Central

Nayyer, Maleeha; Zahid, Shahreen; Hassan, Syed Hammad; Mian, Salman Aziz; Mehmood, Sana; Khan, Haroon Ahmed; Kaleem, Muhammad; Zafar, Muhammad Sohail; Khan, Abdul Samad

2018-01-01

Objective: The objective of this study was to assess the surface properties (microhardness and wear resistance) of various composites and compomer materials. In addition, the methodologies used for assessing wear resistance were compared. Materials and Methods: This study was conducted using restorative material (Filtek Z250, Filtek Z350, QuiXfil, SureFil SDR, and Dyract XP) to assess wear resistance. A custom-made toothbrush simulator was employed for wear testing. Before and after wear resistance, structural, surface, and physical properties were assessed using various techniques. Results: Structural changes and mass loss were observed after treatment, whereas no significant difference in terms of microhardness was observed. The correlation between atomic force microscopy (AFM) and profilometer and between wear resistance and filler volume was highly significant. The correlation between wear resistance and microhardness were insignificant. Conclusions: The AFM presented higher precision compared to optical profilometers at a nanoscale level, but both methods can be used in tandem for a more detailed and precise roughness analysis. PMID:29657526

Emission spectrometric arcing procedure with minimal effect of chemical form of sample. [performed on refractory metal matrix composites

NASA Technical Reports Server (NTRS)

Gordon, W. A.

1975-01-01

Matrix effects related to the chemical form of analyzed materials were studied. An arc in argon was used which was buffered with silver chloride. The effect of chemical form was minimal for a variety of metals, oxides, and carbides representing the most refractory compounds and thermally stable metal-containing molecules. Only four of the most refractory materials known showed significant emission depressions due to incomplete volatilization in the arc system. These results are discussed in terms of vapor pressures of the solid materials placed on the anodes and dissociation reactions of the molecules in the gaseous environment.

Application of the modified transient plane source technique for early detection of liquid explosives

NASA Astrophysics Data System (ADS)

Bateman, Robert; Harris, Adam; Lee, Linda; Howle, Christopher R.; Ackermann, Sarah L. G.

2016-05-01

The paper will review the feasibility of adapting the Modified Transient Plane Source (MTPS) method as a screening tool for early-detection of explosives and hazardous materials. Materials can be distinguished from others based on their inherent thermal properties (e.g. thermal effusivity) in testing through different types of barrier materials. A complimentary advantage to this technique relative to other traditional detection technologies is that it can penetrate reflective barrier materials, such as aluminum, easily. A strong proof-of-principle is presented on application of the MTPS transient thermal property measuring in the early-screening of liquid explosives. The work demonstrates a significant sensitivity to distinguishing a wide range of fluids based on their thermal properties through a barrier material. The work covers various complicating factors to the longer-term adoption of such a method including the impact of carbonization and viscosity. While some technical challenges remain, the technique offers significant advantages in complimenting existing detection methods in being able to penetrate reflective metal containers (e.g. aluminum soft drinkscans) with ease.

Characterization and modeling of an advanced flexible thermal protection material for space applications

NASA Technical Reports Server (NTRS)

Clayton, Joseph P.; Tinker, Michael L.

1991-01-01

This paper describes experimental and analytical characterization of a new flexible thermal protection material known as Tailorable Advanced Blanket Insulation (TABI). This material utilizes a three-dimensional ceramic fabric core structure and an insulation filler. TABI is the leading candidate for use in deployable aeroassisted vehicle designs. Such designs require extensive structural modeling, and the most significant in-plane material properties necessary for model development are measured and analytically verified in this study. Unique test methods are developed for damping measurements. Mathematical models are developed for verification of the experimental modulus and damping data, and finally, transverse properties are described in terms of the inplane properties through use of a 12-dof finite difference model of a simple TABI configuration.

A Potential Function Derivation of a Constitutive Equation for Inelastic Material Response

NASA Technical Reports Server (NTRS)

Stouffer, D. C.; Elfoutouh, N. A.

1983-01-01

Physical and thermodynamic concepts are used to develop a potential function for application to high temperature polycrystalline material response. Inherent in the formulation is a differential relationship between the potential function and constitutive equation in terms of the state variables. Integration of the differential relationship produces a state variable evolution equation that requires specification of the initial value of the state variable and its time derivative. It is shown that the initial loading rate, which is directly related to the initial hardening rate, can significantly influence subsequent material response. This effect is consistent with observed material behavior on the macroscopic and microscopic levels, and may explain the wide scatter in response often found in creep testing.

Transport properties of damaged materials. Cementitious barriers partnership

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

Langton, C.

2014-11-01

The objective of the Cementitious Barriers Partnership (CBP) project is to develop tools to improve understanding and prediction of the long-term structural, hydraulic, and chemical performance of cementitious barriers used in low-level waste storage applications. One key concern for the long-term durability of concrete is the degradation of the cementitious matrix, which occurs as a result of aggressive chemical species entering the material or leaching out in the environment, depending on the exposure conditions. The objective of the experimental study described in this report is to provide experimental data relating damage in cementitious materials to changes in transport properties, whichmore » can eventually be used to support predictive model development. In order to get results within a reasonable timeframe and to induce as much as possible uniform damage level in materials, concrete samples were exposed to freezing and thawing (F/T) cycles. The methodology consisted in exposing samples to F/T cycles and monitoring damage level with ultrasonic pulse velocity measurements. Upon reaching pre-selected damage levels, samples were tested to evaluate changes in transport properties. Material selection for the study was motivated by the need to get results rapidly, in order to assess the relevance of the methodology. Consequently, samples already available at SIMCO from past studies were used. They consisted in three different concrete mixtures cured for five years in wet conditions. The mixtures had water-to-cement ratios of 0.5, 0.65 and 0.75 and were prepared with ASTM Type I cement only. The results showed that porosity is not a good indicator for damage caused by the formation of microcracks. Some materials exhibited little variations in porosity even for high damage levels. On the other hand, significant variations in tortuosity were measured in all materials. This implies that damage caused by internal pressure does not necessarily create additional pore space in the microstructure, but likely creates new thin pathways between existing pore space for species to travel. These results have a significant impact on modeling efforts. Models relating porosity to tortuosity and permeability are unlikely to provide the correct basis for predicting long-term durability of concrete sustaining internal pressures and microcrack formation. Other avenues like the modeling of internal crystallization pressure need to be explored.« less

How to get between the sheets: a review of recent works on the electrochemical exfoliation of graphene materials from bulk graphite

NASA Astrophysics Data System (ADS)

Abdelkader, A. M.; Cooper, A. J.; Dryfe, R. A. W.; Kinloch, I. A.

2015-04-01

Since the beginning of the `graphene era' post-2004, there has been significant interest in developing a high purity, high yield, and scalable fabrication route toward graphene materials for both primary research purposes and industrial production. One suitable approach to graphene production lies in the realm of electrochemical exfoliation, in which a potential difference is applied between a graphite anode/cathode in the presence of an electrolyte-containing medium. Herein we review various works on the electrochemical fabrication of graphene materials specifically through the use of electrochemical intercalation and exfoliation of a graphite source electrode, focusing on the quality and purity of products formed. We categorise the most significant works in terms of anodic and cathodic control, highlighting the merits of the respective approaches, as well as indicating the challenges associated with both procedures.

Functional effects of the bacterial insecticide Bacillus thuringiensis var. kurstaki on aquatic microbial communities.

PubMed

Kreutzweiser, D P; Gringorten, J L; Thomas, D R; Butcher, J T

1996-04-01

Epilithic microbial communities were colonized on leaf disks and exposed to commercial preparations of Bacillus thuringiensis var. kurstaki (Btk) in aquatic microcosms. Responses in terms of microbial respiration, bacterial cell density, protozoan density, and microbial decomposition activity were measured. Test concentrations for treatments with Dipel 64AF and Dipel 8AF in microcosms were the expected environmental concentration (EEC) of 20 IU/ml, 100x the EEC, and 1000x the EEC. Bacterial cell density in the biofilm of leaf disks was significantly increased at concentrations as low as the EEC. There were no concomitant alterations in protozoan density. Microbial respiration was significantly increased, and decomposition activity was significantly decreased, but only at the artificially high concentration of 1000x the EEC. This effect was attributed to the spore-crystal component rather than formulation ingredients. Microbial decomposition of leaf material was also determined in outdoor stream channels treated at concentrations ranging from the EEC to 100x the EEC. Although there tended to be reduced decomposition activity in treated channels, there were no significant differences in mass loss of leaf material between treated and control channels. Various regression, classification, and ordination procedures were applied to the experimental data, and none indicated significant treatment effects. These results from laboratory and controlled field experiments indicate that contamination of watercourses with Btk is unlikely to result in significant adverse effects on microbial community function in terms of detrital decomposition.

Desorption and Bioavailability of PAHs in Contaminated Soil Subjected to Long-Term In Situ Biostimulation

PubMed Central

Richardson, Stephen D.; Aitken, Michael D.

2011-01-01

The distribution and potential bioavailability of polycyclic aromatic hydrocarbons (PAHs) in soil from a former manufactured-gas plant (MGP) site were examined before and after long-term biostimulation under simulated in situ conditions. Treated soil was collected from the oxygenated zones of two continuous-flow columns, one subjected to biostimulation and the other serving as a control, and separated into low- and high-density fractions. In the original soil, over 50% of the total PAH mass was associated with lower-density particles, which comprised < 2% of the total soil mass. However, desorbable fractions of PAHs were much lower in the low-density material than in the high-density material. After over 500 d of biostimulation, significant removal of total PAHs occurred in both the high- and low-density materials (77% and 53%, respectively), with three- and four-ring PAHs accounting for the majority of the observed mass loss. Total PAHs that desorbed over a 28-d period were substantially lower in treated soil from the biostimulated column than in the original soil for both the high-density material (23 versus 63%) and low-density material (5 versus 20%). The fast-desorbing fractions quantified by a two-site desorption model ranged from 0.1 to 0.5 for most PAHs in the original soil but were essentially zero in the biostimulated soil. The fast-desorbing fractions in the original soil underestimated the extent of PAH biodegradation observed in the biostimulated column, and thus was not a good predictor of PAH bioavailability after long-term, simulated in situ biostimulation. PMID:21932296

Comparative color and surface parameters of current esthetic restorative CAD/CAM materials

PubMed Central

2018-01-01

PURPOSE The purpose of this study was to derive and compare the inherent color (hue angle, chroma), translucency (TPSCI), surface gloss (ΔE*SCE-SCI), and surface roughness (Ra) amongst selected shades and brands of three hybrid CAD/CAM blocks [GC Cerasmart (CS); Lava Ultimate (LU); Vita Enamic (VE)]. MATERIALS AND METHODS The specimens (N = 225) were prepared into square-shaped (12 × 12 mm2) with different thicknesses and shades. The measurements of color, translucency, and surface gloss were performed by a reflection spectrophotometer. The surface roughness and surface topography were assessed by white light interferometry. RESULTS Results revealed that hue and chroma values were influenced by the material type, material shade, and material thickness (P < .001). The order of hue angle amongst the materials was LU > CS > VE, whereas the order of chroma was VE > CS > LU. TPSCI results demonstrated a significant difference in terms of material types and material thicknesses (P ≤ .001). TPSCI values of the tested materials were ordered as LU > CS > VE. ΔE*SCE-SCI and Ra results were significantly varied amongst the materials (P < .001) and amongst the shades (P < .05). The order of ΔE*SCE-SCI amongst the materials were as follows LU > VE ≥ CS, whereas the order of Ra was CS ≥ VE > LU. CONCLUSION Nano-ceramic and polymer-infiltrated-feldspathic ceramic-network CAD/CAM materials exhibited different optical, inherent color and surface parameters. PMID:29503712

Tough and deformable glasses with bioinspired cross-ply architectures.

PubMed

Yin, Zhen; Dastjerdi, Ahmad; Barthelat, Francois

2018-05-15

Glasses are optically transparent, hard materials that have been in sustained demand and usage in architectural windows, optical devices, electronics and solar panels. Despite their outstanding optical qualities and durability, their brittleness and low resistance to impact still limits wider applications. Here we present new laminated glass designs that contain toughening cross-ply architectures inspired from fish scales and arthropod cuticles. This seemingly minor enrichment completely transforms the way laminated glass deforms and fractures, and it turns a traditionally brittle material into a stretchy and tough material with little impact on surface hardness and optical quality. Large ply rotation propagates over large volumes, and localization is delayed in tension, even if a strain softening interlayer is used, in a remarkable mechanism which is generated by the kinematics of the plies and geometrical hardening. Compared to traditional laminated glass which degrades significantly in performance when damaged, our cross-ply architecture glass is damage-tolerant and 50 times tougher in energy terms. Despite the outstanding optical qualities and durability of glass, its brittleness and low resistance to impact still limits its wider application. Here we present new laminated glass designs that contain toughening cross-ply architectures inspired from fish scales and arthropod cuticles. Enriching laminated designs with crossplies completely transforms the material deforms and fractures, and turns a traditionally brittle material into a stretchy and tough material - with little impact on surface hardness and optical quality. Large ply rotation propagates over large volumes and localization is delayed in tension because of a remarkable and unexpected geometrical hardening effect. Compared to traditional laminated glass which degrades significantly in performance when damaged, our cross-ply architecture glass is damage-tolerant and it is 50 times tougher in energy terms. Our glass-based, transparent material is highly innovative and it is the first of its kind. We believe it will have impact in broad range of applications in construction, coatings, chemical engineering, electronics, photovoltaics. Copyright © 2018. Published by Elsevier Ltd.

Comparison of clinical outcomes of three different packing materials in the treatment of severe acute otitis externa.

PubMed

Demir, D; Yılmaz, M S; Güven, M; Kara, A; Elden, H; Erkorkmaz, Ü

2018-06-13

To analyse the clinical outcomes of biodegradable synthetic polyurethane foam versus ribbon gauze and ear wick in the treatment of severe acute otitis externa. Ninety-two adults with severe acute otitis externa were randomly assigned to groups receiving ear wick (n = 28), ribbon gauze (n = 34) or biodegradable synthetic polyurethane foam (n = 30). Clinical efficacy, in terms of otalgia, oedema, erythema and tenderness of the external auditory canal, was assessed before packing was applied and at follow up on the 3rd and 7th days of presentation. All packing materials were associated with improved otalgia and oedema on the 3rd day; however, there were significant differences between biodegradable synthetic polyurethane foam and the other packing materials, and there was no significant reduction in tenderness in the biodegradable synthetic polyurethane foam group on the 3rd day. In the ribbon gauze and ear wick groups, improvements in all clinical efficacy scores were statistically significant for all pairwise comparisons. The three packing materials were all quite effective in treating severe acute otitis externa, but ear wick and ribbon gauze were superior to biodegradable synthetic polyurethane foam for relieving signs and symptoms, especially on the 3rd day.

Shared Neural Mechanisms for the Prediction of Own and Partner Musical Sequences after Short-term Piano Duet Training.

PubMed

Lappe, Claudia; Bodeck, Sabine; Lappe, Markus; Pantev, Christo

2017-01-01

Predictive mechanisms in the human brain can be investigated using markers for prediction violations like the mismatch negativity (MMN). Short-term piano training increases the MMN for melodic and rhythmic deviations in the training material. This increase occurs only when the material is actually played, not when it is only perceived through listening, suggesting that learning predictions about upcoming musical events are derived from motor involvement. However, music is often performed in concert with others. In this case, predictions about upcoming actions from a partner are a crucial part of the performance. In the present experiment, we use magnetoencephalography (MEG) to measure MMNs to deviations in one's own and a partner's musical material after both engaged in musical duet training. Event-related field (ERF) results revealed that the MMN increased significantly for own and partner material suggesting a neural representation of the partner's part in a duet situation. Source analysis using beamforming revealed common activations in auditory, inferior frontal, and parietal areas, similar to previous results for single players, but also a pronounced contribution from the cerebellum. In addition, activation of the precuneus and the medial frontal cortex was observed, presumably related to the need to distinguish between own and partner material.

Hurricane Katrina Impact on Water Quality in the East Pearl River, Mississippi

NASA Astrophysics Data System (ADS)

Shiller, A. M.; Shim, M.; Guo, L.; Bianchi, T. S.; Smith, R. W.; Duan, S.

2010-12-01

Hurricanes and other intense storms have previously been reported to cause short term changes in surface water quality. We examined the water quality of the East Pearl River in southern Mississippi both before and after Hurricane Katrina caused extensive damage to the watershed in 2005. Our post-storm sampling began two months after the hurricane, and thus we missed any immediate short-term consequences. However, sampling over the following two years allowed us to examine whether damage to watershed resulted in significant longer term effects on water quality. Interpretation of the time series data is complicated by the natural seasonal and climatic variability of the system. Thus, we utilized property-property plots as well as empirical relationships to compare pre- and post-storm water quality. Based on the variability of our empirical relationships, we estimate that to within 20%, the hurricane-induced vegetative destruction within this river basin has not changed the concentrations of DOC, POC, SPM, pH, or dissolved Fe. Nor has the quality of the DOC, as inferred from lignin-phenol analysis and the Fe-DOC relationship, been significantly changed either. This may be partly due to the slow degradation of woody materials that occurs only over a period of a few years, even in the sub-tropical climate of this region. Also, transport of DOC material from the land, through the soils, and into the river is not always instantaneous because DOC may stay in soils for a long time. Our work can be examined in the context of other research focused on hurricane effects on different time scales. For instance, shorter term hurricane influences, such as immediate flooding, can cause concurrent, short-lived water quality changes. Likewise, if increased hurricane activity (as might result from climate change) results in permanent landscape or ecosystem changes, then significant long-term water quality changes might be expected.

Hurricane Katrina impact on water quality in the East Pearl River, Mississippi

NASA Astrophysics Data System (ADS)

Shiller, Alan M.; Shim, Moo-Joon; Guo, Laodong; Bianchi, Thomas S.; Smith, Richard W.; Duan, Shuiwang

2012-01-01

SummaryHurricanes and other intense storms have previously been reported to cause short-term changes in surface water quality. We examined the water quality of the East Pearl River in southern Mississippi both before and after Hurricane Katrina caused extensive damage to the watershed in 2005. Our post-storm sampling began two months after the hurricane, and thus we missed any immediate short-term consequences. However, sampling over the following two years allowed us to examine whether damage to the watershed resulted in significant longer-term effects on water quality. Interpretation of the time series data is complicated by the natural seasonal and climatic variability of the system. Thus, we utilized chemical property-property plots as well as semi-empirical relationships to compare pre- and post-storm water quality. Our analysis suggests that hurricane-induced vegetative destruction within this river basin has not substantially changed the concentrations of DOC, POC, SPM, pH, or dissolved Fe. However, lignin-phenol analysis of colloidal organic matter did show some significant changes in carbon-normalized concentration as well as in some degradation and source parameters. Nonetheless, even these changes were small and likely temporary. This lack of change may be partly due to the slow degradation of woody materials that occurs only over a period of a few years, even in the sub-tropical climate of this region. Also, transport of DOC material from the land, through the soils, and into the river is not always instantaneous because DOC may stay in soils for a long time. Our work can be examined in the context of other research focused on hurricane effects on different time scales. For instance, shorter term hurricane influences, such as immediate flooding, can cause concurrent, short-lived water quality changes. Likewise, if increased hurricane activity (as might result from climate change) results in permanent landscape or ecosystem changes, then significant long-term water quality changes might be expected.

Boron-doped manganese dioxide for supercapacitors.

PubMed

Chi, Hong Zhong; Li, Yuwei; Xin, Yingxu; Qin, Haiying

2014-11-11

The addition of boron as a dopant during the reaction between carbon fiber and permanganate led to significant enhancement of the growth-rate and formation of the porous framework. The doped MnO2 was superior to the pristine sample as electrode materials for supercapacitors in terms of the specific capacitance and rate capability.

Environmental Assessment Housing Transfer at Grand Forks AFB, North Dakota

DTIC Science & Technology

2005-01-27

AIR FORCE BASE ...Equipment…………. 28 9 ACRONYMS, ABBREVIATIONS, AND TERMS AAM Annual Arithmetic Mean ACM Asbestos-Containing Material AFB Air Force Base AFI Air ...of No Significant Impact ft Feet ft3/s feet cubed per meter 10 GFAFB Grand Forks Air Force Base HAP Hazardous Air Pollutants hr Hour

Representation of Sports and Recreational Activities in Primary School English Language Coursebooks

ERIC Educational Resources Information Center

Zorba, Mehmet Galip; Arikan, Arda

2012-01-01

Studying coursebooks and instructional materials in terms of their cultural, social and value-based qualities has been a significant aspect of research in language education since what is inherent in coursebooks directly affects users' perspective. In this research study, contents of English language coursebooks used in Turkish senior primary…

Short-Term Impact Evaluation of a Social Marketing Campaign to Prevent Syphilis Among Men Who Have Sex With Men

PubMed Central

Darrow, William W.; Biersteker, Susan

2008-01-01

Objectives. We carried out an independent short-term impact evaluation of a social marketing campaign designed to reduce syphilis infections among men who have sex with men in south Florida in 2004. Methods. Venue-based surveys were conducted shortly after the campaign began and 6 months later to assess changes in exposure to campaign materials, awareness, knowledge about syphilis, perceptions of risk, sexual behavior, clinic visits, and testing and treatment for syphilis among participants. Results. Exposure to social marketing campaign materials increased from 18.0% at baseline to 36.5% at follow-up (P< .001). Awareness of syphilis and perceptions of risk increased among Broward County residents but not among Miami–Dade County residents. Risky sexual practices and patterns of recreational drug use did not change. No significant increases in knowledge, clinic visits, or testing or treatment for syphilis among participants were detected over the 6-month study period. Conclusions. None of the campaign objectives were fully met. The interventions were insufficient to produce a significant impact among men who have sex with men in south Florida. PMID:18172146

Long-Term Biostability of Self-Assembling Protein Polymers in the Absence of Covalent Crosslinking

PubMed Central

Sallach, Rory E.; Cui, Wanxing; Balderrama, Fanor; Martinez, Adam W.; Wen, Jing; Haller, Carolyn A.; Taylor, Jeannette V.; Wright, Elizabeth R.; Long, Robert C.; Chaikof, Elliot L.

2009-01-01

Unless chemically crosslinked, matrix proteins, such as collagen or silk, display a limited lifetime in vivo with significant degradation observed over a period of weeks. Likewise, amphiphilic peptides, lipopeptides, or glycolipids that self-assemble through hydrophobic interactions to form thin films, fiber networks, or vesicles do not demonstrate in vivo biostability beyond a few days. We report herein that a self-assembling, recombinant elastin-mimetic triblock copolymer elicited minimal inflammatory response and displayed robust in vivo stability for periods exceeding 1 year, in the absence of either chemical or ionic crosslinking. Specifically, neither a significant inflammatory response nor calcification was observed upon implantation of test materials into the peritoneal cavity or subcutaneous space of a mouse model. Moreover, serial quantitative magnetic resonance imaging, evaluation of pre- and post-explant ultrastructure by cryo-high resolution scanning electron microscopy, and an examination of implant mechanical responses revealed substantial preservation of form, material architecture, and biomechanical properties, providing convincing evidence of a non-chemically or ionically crosslinked protein polymer system that exhibits long-term stability in vivo. PMID:19854505

Short-term impact evaluation of a social marketing campaign to prevent syphilis among men who have sex with men.

PubMed

Darrow, William W; Biersteker, Susan

2008-02-01

We carried out an independent short-term impact evaluation of a social marketing campaign designed to reduce syphilis infections among men who have sex with men in south Florida in 2004. Venue-based surveys were conducted shortly after the campaign began and 6 months later to assess changes in exposure to campaign materials, awareness, knowledge about syphilis, perceptions of risk, sexual behavior, clinic visits, and testing and treatment for syphilis among participants. Exposure to social marketing campaign materials increased from 18.0% at baseline to 36.5% at follow-up (P< .001). Awareness of syphilis and perceptions of risk increased among Broward County residents but not among Miami-Dade County residents. Risky sexual practices and patterns of recreational drug use did not change. No significant increases in knowledge, clinic visits, or testing or treatment for syphilis among participants were detected over the 6-month study period. None of the campaign objectives were fully met. The interventions were insufficient to produce a significant impact among men who have sex with men in south Florida.

49 CFR 173.59 - Description of terms for explosives.

Code of Federal Regulations, 2013 CFR

2013-10-01

... MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS SHIPPERS... other material containing only propellant explosive. The term excludes charges, shaped, commercial...-flammable materials, in which only the explosive component is the primer. Cases, combustible, empty, without...

49 CFR 173.59 - Description of terms for explosives.

Code of Federal Regulations, 2014 CFR

2014-10-01

... MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS SHIPPERS... other material containing only propellant explosive. The term excludes charges, shaped, commercial...-flammable materials, in which only the explosive component is the primer. Cases, combustible, empty, without...

Thermal Conductivity and Sintering Behavior of Advanced Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2002-01-01

Advanced thermal barrier coatings, having significantly reduced long-term thermal conductivities, are being developed using an approach that emphasizes real-time monitoring of thermal conductivity under conditions that are engine-like in terms of temperatures and heat fluxes. This is in contrast to the traditional approach where coatings are initially optimized in terms of furnace and burner rig durability with subsequent measurement in the as-processed or furnace-sintered condition. The present work establishes a laser high-heat-flux test as the basis for evaluating advanced plasma-sprayed and physical vapor-deposited thermal barrier coatings under the NASA Ultra Efficient Engine Technology (UEET) Program. The candidate coating materials for this program are novel thermal barrier coatings that are found to have significantly reduced thermal conductivities due to an oxide-defect-cluster design. Critical issues for designing advanced low conductivity coatings with improved coating durability are also discussed.

Silicon Oxycarbide Aerogels for High-Temperature Thermal Insulation

NASA Technical Reports Server (NTRS)

Evans, Owen; Rhine, Wendell; Coutinho, Decio

2010-01-01

This work has shown that the use of SOC-A35 leads to aerogel materials containing a significant concentration of carbidic species and limited amorphous free carbon. Substitution of the divalent oxide species in silica with tetravalent carbidic carbon has directly led to materials that exhibit increased network viscosity, reduced sintering, and limited densification. The SiOC aerogels produced in this work have the highest carbide content of any dense or porous SiOC glass reported in the literature at that time, and exhibit tremendous long-term thermal stability.

Identifying Major Transitions in the Evolution of Lithic Cutting Edge Production Rates

PubMed Central

Clarkson, Chris

2016-01-01

The notion that the evolution of core reduction strategies involved increasing efficiency in cutting edge production is prevalent in narratives of hominin technological evolution. Yet a number of studies comparing two different knapping technologies have found no significant differences in edge production. Using digital analysis methods we present an investigation of raw material efficiency in eight core technologies broadly representative of the long-term evolution of lithic technology. These are bipolar, multiplatform, discoidal, biface, Levallois, prismatic blade, punch blade and pressure blade production. Raw material efficiency is assessed by the ratio of cutting edge length to original core mass. We also examine which flake attributes contribute to maximising raw material efficiency, as well as compare the difference between expert and intermediate knappers in terms of cutting edge produced per gram of core. We identify a gradual increase in raw material efficiency over the broad sweep of lithic technological evolution. The results indicate that the most significant transition in efficiency likely took place with the introduction of small foliate biface, Levallois and prismatic blade knapping, all introduced in the Middle Stone Age / Middle Palaeolithic among early Homo sapiens and Neanderthals. This suggests that no difference in raw material efficiency existed between these species. With prismatic blade technology securely dated to the Middle Palaeolithic, by including the more recent punch and pressure blade technology our results dispel the notion that the transition to the Upper Palaeolithic was accompanied by an increase in efficiency. However, further increases in cutting edge efficiency are evident, with pressure blades possessing the highest efficiency in this study, indicating that late/epi-Palaeolithic and Neolithic blade technologies further increased efficiency. PMID:27936135

Identifying Major Transitions in the Evolution of Lithic Cutting Edge Production Rates.

PubMed

Muller, Antoine; Clarkson, Chris

2016-01-01

The notion that the evolution of core reduction strategies involved increasing efficiency in cutting edge production is prevalent in narratives of hominin technological evolution. Yet a number of studies comparing two different knapping technologies have found no significant differences in edge production. Using digital analysis methods we present an investigation of raw material efficiency in eight core technologies broadly representative of the long-term evolution of lithic technology. These are bipolar, multiplatform, discoidal, biface, Levallois, prismatic blade, punch blade and pressure blade production. Raw material efficiency is assessed by the ratio of cutting edge length to original core mass. We also examine which flake attributes contribute to maximising raw material efficiency, as well as compare the difference between expert and intermediate knappers in terms of cutting edge produced per gram of core. We identify a gradual increase in raw material efficiency over the broad sweep of lithic technological evolution. The results indicate that the most significant transition in efficiency likely took place with the introduction of small foliate biface, Levallois and prismatic blade knapping, all introduced in the Middle Stone Age / Middle Palaeolithic among early Homo sapiens and Neanderthals. This suggests that no difference in raw material efficiency existed between these species. With prismatic blade technology securely dated to the Middle Palaeolithic, by including the more recent punch and pressure blade technology our results dispel the notion that the transition to the Upper Palaeolithic was accompanied by an increase in efficiency. However, further increases in cutting edge efficiency are evident, with pressure blades possessing the highest efficiency in this study, indicating that late/epi-Palaeolithic and Neolithic blade technologies further increased efficiency.

Comparative color and surface parameters of current esthetic restorative CAD/CAM materials.

PubMed

Egilmez, Ferhan; Ergun, Gulfem; Cekic-Nagas, Isil; Vallittu, Pekka Kalevi; Lassila, Lippo Veli Juhana

2018-02-01

The purpose of this study was to derive and compare the inherent color (hue angle, chroma), translucency (TP SCI ), surface gloss (ΔE * SCE-SCI ), and surface roughness (R a ) amongst selected shades and brands of three hybrid CAD/CAM blocks [GC Cerasmart (CS); Lava Ultimate (LU); Vita Enamic (VE)]. The specimens (N = 225) were prepared into square-shaped (12 × 12 mm 2 ) with different thicknesses and shades. The measurements of color, translucency, and surface gloss were performed by a reflection spectrophotometer. The surface roughness and surface topography were assessed by white light interferometry. Results revealed that hue and chroma values were influenced by the material type, material shade, and material thickness ( P < .001). The order of hue angle amongst the materials was LU > CS > VE, whereas the order of chroma was VE > CS > LU. TP SCI results demonstrated a significant difference in terms of material types and material thicknesses ( P ≤ .001). TP SCI values of the tested materials were ordered as LU > CS > VE. ΔE * SCE-SCI and R a results were significantly varied amongst the materials ( P < .001) and amongst the shades ( P < .05). The order of ΔE * SCE-SCI amongst the materials were as follows LU > VE ≥ CS, whereas the order of R a was CS ≥ VE > LU. Nano-ceramic and polymer-infiltrated-feldspathic ceramic-network CAD/CAM materials exhibited different optical, inherent color and surface parameters.

Discoloration of different esthetic restorative materials: A spectrophotometric evaluation

PubMed Central

Ceci, Matteo; Viola, Matteo; Rattalino, Davide; Beltrami, Riccardo; Colombo, Marco; Poggio, Claudio

2017-01-01

Objective: A crucial property of esthetic restorative materials is their long-term color stability. The aim of this in vitro study was to evaluate the color stability of esthetic restorative materials (one microfilled flowable composite, one nanofilled composite, one nanoybrid composite, one microfilled composite, and one nanoybrid ormocer-based composite) after surface roughening with cola and exposure to different staining solutions (coffee and red wine). Materials and Methods: All materials were polymerized into silicone rubber rings (2 mm × 6 mm × 8 mm) to obtain 150 specimens identical in size. Seventy-five specimens of Group A were first exposed to cola for 24 h, and then samples were immersed in coffee or red wine over a 28-day test period. A colorimetric evaluation, according to the CIE L*a*b* system, was performed at 7, 14, 21, 28 days. Shapiro–Wilk test and Kruskal–Wallis analysis of variance were applied to assess significant differences among restorative materials. Means were compared with Scheffe's multiple comparison test at the 0.05 level of significance. Results: Specimens of Group A showed higher variations when compared with Group B's specimens (P < 0.05). After 28 days, the immersion protocols caused a clinically perceivable color change for all materials tested (P < 0.05). CeramX Universal and Admira Fusion showed the lowest ΔE variations (P < 0.05). Conclusions: Staining beverages caused significant discolorations for all the materials tested. The first exposure to cola enhanced the subsequent staining with coffee or red wine. Nanohybrid composites reported the lowest color variations. PMID:28729784

Screening of advanced cladding materials and UN-U3Si5 fuel

NASA Astrophysics Data System (ADS)

Brown, Nicholas R.; Todosow, Michael; Cuadra, Arantxa

2015-07-01

In the aftermath of Fukushima, a focus of the DOE-NE Advanced Fuels Campaign has been the development of advanced nuclear fuel and cladding options with the potential for improved performance in an accident. Uranium dioxide (UO2) fuels with various advanced cladding materials were analyzed to provide a reference for cladding performance impacts. For advanced cladding options with UO2 fuel, most of the cladding materials have some reactivity and discharge burn-up penalty (in GWd/t). Silicon carbide is one exception in that the reactor physics performance is predicted to be very similar to zirconium alloy cladding. Most candidate claddings performed similar to UO2-Zr fuel-cladding in terms of safety coefficients. The clear exception is that Mo-based materials were identified as potentially challenging from a reactor physics perspective due to high resonance absorption. This paper also includes evaluation of UN-U3Si5 fuels with Kanthal AF or APMT cladding. The objective of the U3Si5 phase in the UN-U3Si5 fuel concept is to shield the nitride phase from water. It was shown that UN-U3Si5 fuels with Kanthal AF or APMT cladding have similar reactor physics and fuel management performance over a wide parameter space of phase fractions when compared to UO2-Zr fuel-cladding. There will be a marginal penalty in discharge burn-up (in GWd/t) and the sensitivity to 14N content in UN ceramic composites is high. Analysis of the rim effect due to self-shielding in the fuel shows that the UN-based ceramic fuels are not expected to have significantly different relative burn-up distributions at discharge relative to the UO2 reference fuel. However, the overall harder spectrum in the UN ceramic composite fuels increases transuranic build-up, which will increase long-term activity in a once-thru fuel cycle but is expected to be a significant advantage in a fuel cycle with continuous recycling of transuranic material. It is recognized that the fuel and cladding properties assumed in these assessments are preliminary, and that additional data are necessary for these materials, most significantly under irradiation.

In vitro investigation of the performance of different restorative materials under cast circumferential clasps for removable dental prostheses.

PubMed

Pospiech, Peter; Nagel, Florian; Gebhart, Florian; Nothdurft, Frank P; Mitov, Gergo

2012-12-01

The objective of this in vitro study was to investigate the behavior of different composite restorative materials under the load of cast circumferential clasps for removable dental prostheses (RDPs). In 60 human molars, standardized mesial-occlusal-distal cavities were prepared. The cavities were restored with the following materials: Definite, Tetric Ceram, SureFil, Heliomolar RO, Ariston pHc, and Oralloy, and provided with a rest seat. The rest seats were subjected to 5,000 cycles of thermal cycling and 1,200,000 masticatory cycles in a mastication simulator via cobalt-chromium circumferential clasps cast to standardized frameworks in a laboratory model designed to simulate the biomechanics of a free-end denture base. Fracture analysis of the restorations was performed by light microscopy. Before and after loading, material wear was measured with a 3D-laser scanner, and an analysis of the marginal quality was performed in an SEM at ×200 applying the replica technique. No significant differences in the fracture behavior among the composite materials were found; the amalgam control group showed a significantly higher fracture resistance. Regarding the wear of the materials, the composites Definite and SureFil exhibited a behavior similar to that of amalgam. The other composites demonstrated higher wear rates. The initial marginal quality was significantly worse for Ariston pHc. The marginal adaptation decreased significantly after thermal and mechanical loading for Definite and Ariston pHc. In terms of the investigated aspects of mechanical performance, the tested composites seemed to be inferior to amalgam. Further clinical studies are needed to evaluate the ability of composite restorations to provide support for RDP clasps. The use of composites as direct restoration materials should be avoided in teeth, which serve as abutments for clasp-retained RDPs.

Parental material and cultivation determine soil bacterial community structure and fertility.

PubMed

Sun, Li; Gao, Jusheng; Huang, Ting; Kendall, Joshua R A; Shen, Qirong; Zhang, Ruifu

2015-01-01

Microbes are the key components of the soil environment, playing important roles during soil development. Soil parent material provides the foundation elements that comprise the basic nutritional environment for the development of microbial community. After 30 years artificial maturation of cultivation, the soil developments of three different parental materials were evaluated and bacterial community compositions were investigated using the high-throughput sequencing approach. Thirty years of cultivation increased the soil fertility and soil microbial biomass, richness and diversity, greatly changed the soil bacterial communities, the proportion of phylum Actinobacteria decreased significantly, while the relative abundances of the phyla Acidobacteria, Chloroflexi, Gemmatimonadetes, Armatimonadetes and Nitrospira were significantly increased. Soil bacterial communities of parental materials were separated with the cultivated ones, and comparisons of different soil types, granite soil and quaternary red clay soil were similar and different with purple sandy shale soil in both parental materials and cultivated treatments. Bacterial community variations in the three soil types were affected by different factors, and their alteration patterns in the soil development also varied with soil type. Soil properties (except total potassium) had a significant effect on the soil bacterial communities in all three soil types and a close relationship with abundant bacterial phyla. The amounts of nitrogen-fixing bacteria as well as the abundances of the nifH gene in all cultivated soils were higher than those in the parental materials; Burkholderia and Rhizobacte were enriched significantly with long-term cultivation. The results suggested that crop system would not deplete the nutrients of soil parental materials in early stage of soil maturation, instead it increased soil fertility and changed bacterial community, specially enriched the nitrogen-fixing bacteria to accumulate nitrogen during soil development. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Microbiome manipulation with faecal microbiome transplantation as a therapeutic strategy in Clostridium difficile infection

PubMed Central

Marchesi, J.R.; Thursz, M.R.; Williams, H.R.T.

2015-01-01

Faecal microbiome transplantation (FMT) has generated huge recent interest as it presents a potential solution to a significant clinical problem—the increasing incidence of Clostridium difficile infection (CDI). In the short term, however, there remain many practical questions regarding its use, including the optimal selection of donors, material preparation and the mechanics of delivery. In the longer term, enhanced understanding of the mechanisms of action of FMT may potentiate novel therapies, such as targeted manipulation of the microbiome in CDI and beyond. PMID:25193538

43 CFR 3602.21 - What payment terms apply to my mineral materials sales contract?

Code of Federal Regulations, 2011 CFR

2011-10-01

... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false What payment terms apply to my mineral... Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) MINERAL MATERIALS DISPOSAL Mineral Materials Sales Administration of Sales § 3602.21 What payment terms...

43 CFR 3602.21 - What payment terms apply to my mineral materials sales contract?

Code of Federal Regulations, 2013 CFR

2013-10-01

... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false What payment terms apply to my mineral... Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) MINERAL MATERIALS DISPOSAL Mineral Materials Sales Administration of Sales § 3602.21 What payment terms...

43 CFR 3602.21 - What payment terms apply to my mineral materials sales contract?

Code of Federal Regulations, 2014 CFR

2014-10-01

... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false What payment terms apply to my mineral... Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) MINERAL MATERIALS DISPOSAL Mineral Materials Sales Administration of Sales § 3602.21 What payment terms...

43 CFR 3602.21 - What payment terms apply to my mineral materials sales contract?

Code of Federal Regulations, 2012 CFR

2012-10-01

... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false What payment terms apply to my mineral... Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) MINERAL MATERIALS DISPOSAL Mineral Materials Sales Administration of Sales § 3602.21 What payment terms...

High conductive, long-term durable, anhydrous proton conductive solid-state electrolyte based on a metal-organic framework impregnated with binary ionic liquids: Synthesis, characteristic and effect of anion

NASA Astrophysics Data System (ADS)

Chen, Hui; Han, Shu-Yan; Liu, Rui-Heng; Chen, Teng-Fei; Bi, Kai-Lun; Liang, Jian-Bo; Deng, Yu-Heng; Wan, Chong-Qing

2018-02-01

Incorporating ionic liquids (abbreviated as ILs) into porous metal-organic framework (MOF) to obtain ILs@MOF nanocomposites is documented as a feasible method to achieve new type of anhydrous proton conductor with high performance. We newly synthesized a series of ILs with different acid counter anions (R-SO3-) and their ILs@MOF hybrid materials, i.e. SA-EIMS@MIL-101, MSA-EIMS@MIL-101 and PTSA-EIMS@MIL-101 (SA = sulfate acid, MSA = methanesulfonate acid, PTSA = p-toluenesulfonate acid, EIMS = 1-(1-ethyl-3-imidazolium)propane-3-sulfonate). Such hybrid materials displayed as anhydrous proton conduction with long-term durability even heated at 150 °C open to air. σ value of SA-EIMS@MIL-101 is up to 1.89 × 10-3 S cm-1, being in the range of the most conductive MOF-based materials. MOF support exhibited favorable proton transport and long-term retention for ILs. Anion volumes of R-SO3- displayed significant effects on the proton conductivity of such hybrid ILs@MOF materials. The smaller the van der Waals volume of R-SO3- is, the higher the conductivity of ILs@MOF is. This work suggests that the combination of a variety of the incorporated ILs and a MOF framework would afford high proton transport and gives an idea to explore the safe, anhydrous, solid-state electrolyte for high temperature proton exchange membrane fuel cell.

Long-term Bond Strength between Layering Indirect Composite Material and Zirconia Coated with Silicabased Ceramics.

PubMed

Fushiki, Ryosuke; Komine, Futoshi; Honda, Junichi; Kamio, Shingo; Blatz, Markus B; Matsumura, Hideo

2015-06-01

This study evaluated the long-term shear bond strength between an indirect composite material and a zirconia framework coated with silica-based ceramics, taking the effect of different primers into account. A total of 165 airborne-particle abraded zirconia disks were subjected to one of three pretreatments: no pretreatment (ZR-AB), airborne-particle abrasion of zirconia coated with feldspathic porcelain (ZR-PO-AB), and 9.5% hydrofluoric acid etching of zirconia coated with feldspathic porcelain (ZR-PO-HF). An indirect composite material (Estenia C&B) was then bonded to the zirconia disks after they were treated with one of the following primers: Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB + Activator), Estenia Opaque Primer (EOP), Porcelain Liner M Liquid B (PLB), or no priming (CON, control group). Shear bond strength was tested after 100,000 thermocycles, and the data were analyzed using the Steel-Dwass U-test (α = 0.05). For ZR-PO-AB and ZR-PO-HF specimens, bond strength was highest in the CPB+Activator group (25.8 MPa and 22.4 MPa, respectively). Bond strengths were significantly lower for ZR-AB specimens in the CON and PLB groups and for ZR-PO-AB specimens in the CON, CPB, and EOP groups. Combined application of a hydrophobic phosphate monomer (MDP) and silane coupling agent enhanced the long-term bond strength of indirect composite material to a zirconia coated with silica-based ceramics.

Challenges in design of Kitaev materials: Magnetic interactions from competing energy scales

NASA Astrophysics Data System (ADS)

Winter, Stephen M.; Li, Ying; Jeschke, Harald O.; Valentí, Roser

2016-06-01

In this study, we reanalyze the magnetic interactions in the Kitaev spin-liquid candidate materials Na2IrO3,α -RuCl3 , and α -Li2IrO3 using nonperturbative exact diagonalization methods. These methods are more appropriate given the relatively itinerant nature of the systems suggested in previous works. We treat all interactions up to third neighbors on equal footing. The computed terms reveal significant long-range coupling, bond anisotropy, and/or off-diagonal couplings which we argue naturally explain the observed ordered phases in these systems. Given these observations, the potential for realizing the spin-liquid state in real materials is analyzed, and synthetic challenges are defined and explained.

Determine Important Nuclear Fragmentation Processes for Space Radiation Protection in Human Space Explorations

NASA Technical Reports Server (NTRS)

Lin, Zi-wei

2004-01-01

Space radiation from cosmic ray particles is one of the main challenges for long-term human space explorations such as a permanent moon base or a trip to Mars. Material shielding may provide significant radiation protection to astronauts, and models have been developed in order to evaluate the effectiveness of different shielding materials and to predict radiation environment inside the spacecraft. In this study we determine the nuclear fragmentation cross sections which will most effect the radiation risk behind typical radiation shielding materials. These cross sections thus need more theoretical studies and accurate experimental measurements in order for us to more precisely predict the radiation risk in human space explorations.

Determine Important Nuclear Fragmentation Processes for Space Radiation Protection in Human Space Explorations

NASA Technical Reports Server (NTRS)

Lin, Zi-Wei

2004-01-01

Space radiation from cosmic ray particles is one of the main challenges for long-term human space explorations such as a permanent moon base or a trip to Mars. Material shielding may provide significant radiation protection to astronauts, and models have been developed in order to evaluate the effectiveness of different shielding materials and to predict radiation environment inside the spacecraft. In this study we determine the nuclear fragmentation cross sections which will most affect the radiation risk behind typical radiation shielding materials. These cross sections thus need more theoretical studies and accurate experimental measurements in order for us to more precisely predict the radiation risk in human space exploration.

Determine Important Nuclear Fragmentation Processes for Space Radiation Protection in Human Space Explorations

NASA Technical Reports Server (NTRS)

Lin, Zi-Wei

2004-01-01

Space radiation from cosmic ray particles is one of the main challenges for long-term human space explorations such as a permanent moon base or a trip to Mars. Material shielding may provide significant radiation protection to astronauts, and models have been developed in order to evaluate the effectiveness of different shielding materials and to predict radiation environment inside the spacecraft. In this study we determine the nuclear fragmentation cross sections which will most affect the radiation risk behind typical radiation shielding materials. These cross sections thus need more theoretical studies and accurate experimental measurements in order for us to more precisely predict the radiation risk in human space explorations.

Long-term thermal stability of nanoclusters in ODS-Eurofer steel: An atom probe tomography study

NASA Astrophysics Data System (ADS)

Zilnyk, K. D.; Pradeep, K. G.; Choi, P.; Sandim, H. R. Z.; Raabe, D.

2017-08-01

Oxide-dispersion strengthened materials are important candidates for several high-temperature structural applications in advanced nuclear power plants. Most of the desirable mechanical properties presented by these materials are due to the dispersion of stable nanoparticles in the matrix. Samples of ODS-Eurofer steel were annealed for 4320 h (6 months) at 800 °C. The material was characterized using atom probe tomography in both conditions (prior and after heat treatment). The particles number density, size distribution, and chemical compositions were determined. No significant changes were observed between the two conditions indicating a high thermal stability of the Y-rich nanoparticles at 800 °C.

Comparative in vitro study for orthodontic adhesives relatively to sorption and solubility

NASA Astrophysics Data System (ADS)

Muntean, A.; Mesaros, A.; Festila, D.; Moldovan, M.; Boboia, S.; Mesaros, M.

2015-12-01

Water sorption and solubility correspond to undesirable physical characteristics because it may cause micro leakage and dissolution for composite materials used for orthodontic attachment bonding. The aim of this study was to evaluate the performance of four composite materials employed in orthodontic as adhesives, relatively to water and 50% alcoholic solution, by means of in vitro tests of sorption and solubility. We used an experimental composite sealer SO® (ICCRR Cluj Napoca) and 3 commercial products already on the market: Blugloo® (Ormco), Opal Bond MV® (Ultradent) and Bond It® (DB orthodontics). Data were recorded and specific statistic tests were performed, revealing significant differences for all materials relatively to tested solutions. The materials expressed an adequate performance in terms of sorption and solubility, offering various alternatives for orthodontists.

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.

Strategy in short-term memory for pictures in childhood: a near-infrared spectroscopy study.

PubMed

Sanefuji, Masafumi; Takada, Yui; Kimura, Naoko; Torisu, Hiroyuki; Kira, Ryutaro; Ishizaki, Yoshito; Hara, Toshiro

2011-02-01

In Baddeley's working memory model, verbalizable visual material such as pictures are recoded into a phonological form and then rehearsed, while auditory material is rehearsed directly. The recoding and rehearsal processes are mediated by articulatory control process in the left ventrolateral prefrontal cortex (VLPFC). Developmentally, the phonological strategy for serially-presented visual material emerges around 7 years of age, while that for auditory material is consistently present by 4 years of age. However, the strategy change may actually be correlated with memory ability as this usually increases with age. To investigate the relationship between the strategy for pictures and memory ability, we monitored the left VLPFC activation in 5 to 11 year-old children during free recall of visually- or auditorily-presented familiar objects using event-related near-infrared spectroscopy. We hypothesized that the phonological strategy of rehearsal and recoding for visual material would provoke greater activation than only rehearsal for auditory material in the left VLPFC. Therefore, we presumed that the activation difference for visual material compared with auditory material in the left VLPFC may represent the tendency to use a phonological strategy. We found that the activation difference in the left VLPFC showed a significant positive correlation with memory ability but not with age, suggesting that children with high memory ability make more use of phonological strategy for pictures. The present study provides functional evidence that the strategy in short-term memory for pictures shifts gradually from non-phonological to phonological as memory ability increases in childhood. Copyright © 2010 Elsevier Inc. All rights reserved.

The efficacy of tailored print materials in promoting colorectal cancer screening: results from a randomized trial involving callers to the National Cancer Institute's Cancer Information Service.

PubMed

Marcus, Alfred C; Mason, Mondi; Wolfe, Pam; Rimer, Barbara K; Lipkus, Isaac; Strecher, Victor; Warneke, Richard; Morra, Marion E; Allen, Amy Reasinger; Davis, Sharon W; Gaier, Amy; Graves, Carlan; Julesberg, Karen; Nguyen, Lynne; Perocchia, Rosemarie; Speyer, Jo Beth; Wagner, Doug; Thomsen, Chris; Bright, Mary Anne

2005-01-01

In this large randomized trial among callers to the Cancer Information Service (CIS), tailored print materials were tested for efficacy in promoting colorectal cancer (CRC) screening (fecal occult blood test [FOBT], flexible sigmoidoscopy, or colonoscopy). All participants completed baseline interviews at the end of their usual service calls to the CIS, as well as short-term (6-month) and longer-term (14-month) telephone follow-up interviews. The study sample (n = 4,014) was restricted to English-speaking CIS callers 50 + years of age, who would be eligible for CRC screening at 14 months follow-up and did not call the CIS about CRC or CRC screening. Four experimental conditions were compared: a single untailored (SU) mailout of print material (the control condition); a single tailored (ST) mailout of print material; four (multiple) tailored (MT) mailouts of print materials spanning 12 months, all of which were tailored to information obtained at baseline; and four (multiple) retailored (MRT) mailouts also spanning 12 months, with retailoring of the print materials (mailouts 2, 3, and 4) based on updated information obtained from the 6-month follow-up interviews. Consistent with the main hypothesis of this trial, a significant linear trend across the SU, ST, MT, and MRT groups was found at 14 months (42%, 44%, 51%, and 48%, respectively, p = 0.05). Only for MT was there a significant difference compared with SU (p = 0.03) for the sample as a whole, while no differences were found for MT vs. MRT at 14 months. Significant moderator effects in the predicted direction were found among females, younger participants, and among those with a history of CRC screening, all of which involved the SU vs. MT MRT comparisons. Only among younger participants (ages 50-59) was there a difference between SU vs. ST at 14 months. Given these results, we conclude from this trial the following: (1) the MRT intervention failed to show added benefit beyond the MT intervention, (2) the significant intervention effects involving the MT and MRT conditions can be explained by tailoring and/or the longitudinal nature of both interventions, and (3) the most compelling evidence in support of tailoring was found for the ST condition among younger participants, where a significant need for interventions exists at the national level. Directions for future research are discussed in light of the results summarized above.

Optically-controlled long-term storage and release of thermal energy in phase-change materials.

PubMed

Han, Grace G D; Li, Huashan; Grossman, Jeffrey C

2017-11-13

Thermal energy storage offers enormous potential for a wide range of energy technologies. Phase-change materials offer state-of-the-art thermal storage due to high latent heat. However, spontaneous heat loss from thermally charged phase-change materials to cooler surroundings occurs due to the absence of a significant energy barrier for the liquid-solid transition. This prevents control over the thermal storage, and developing effective methods to address this problem has remained an elusive goal. Herein, we report a combination of photo-switching dopants and organic phase-change materials as a way to introduce an activation energy barrier for phase-change materials solidification and to conserve thermal energy in the materials, allowing them to be triggered optically to release their stored latent heat. This approach enables the retention of thermal energy (about 200 J g -1 ) in the materials for at least 10 h at temperatures lower than the original crystallization point, unlocking opportunities for portable thermal energy storage systems.

Sustainable hemp-based composites for the building industry application

NASA Astrophysics Data System (ADS)

Schwarzova, Ivana; Stevulova, Nadezda; Junak, Jozef; Hospodarova, Viola

2017-07-01

Sustainability goals are essential driving principles for the development of innovative materials in the building industry. Natural plant (e.g. hemp) fibers represent an attractive alternative as reinforcing material due to its good properties and sustainability prerequisites. In this study, hemp-based composite materials, designed for building application as non-load bearing material, providing both thermal insulation and physico-mechanical properties, are presented. Composite materials were produced by bonding hemp hurds with a novel inorganic binder (MgO-based cement) and then were characterized in terms of physical properties (bulk density, water absorption), thermal properties (thermal conductivity) and mechanical properties (compressive and tensile strength). The composites exhibited promising physical, thermal and mechanical characteristics, generally comparable to commercially available products. In addition, the hemp-based composites have the advantage of a significantly low environmental impact (thanks to the nature of both the dispersed and the binding phase) and no negative effects on human health. All things considered, the composite materials seem like very promising materials for the building industry application.

Metal roof corrosion related to volcanic ash deposition

NASA Astrophysics Data System (ADS)

Oze, C.; Cole, J. W.; Scott, A.; Wilson, T.; Wilson, G.; Gaw, S.; Hampton, S.; Doyle, C.; Li, Z.

2013-12-01

Volcanoes produce a wide range of hazards capable of leading to increased rates of corrosion to the built environment. Specifically, widely distributed volcanic ash derived from explosive volcanic eruptions creates both short- and long-term hazards to infrastructure including increased corrosion to exposed building materials such as metal roofing. Corrosion has been attributed to volcanic ash in several studies, but these studies are observational and are beset by limitations such as not accounting for pre-existing corrosion damage and/or other factors that may have also directly contributed to corrosion. Here, we evaluate the corrosive effects of volcanic ash, specifically focusing on the role of ash leachates, on a variety of metal roofing materials via weathering chamber experiments. Weathering chamber tests were carried out for up to 30 days using a synthetic ash dosed with an acidic solution to produce a leachate comparable to a real volcanic ash. Visual, chemical and surface analyses did not definitively identify significant corrosion in any of the test roofing metal samples. These experiments attempted to provide quantitative information with regards to the rates of corrosion of different types of metal roof materials. However, they demonstrate that no significant corrosion was macroscopically or microscopically present on any of the roofing surfaces despite the presence of corrosive salts after a duration of thirty days. These results suggest ash leachate-related corrosion is not a major or immediate concern in the short-term (< 1 month).

Pharmacies, communication, and condoms. Research report: Mexico.

PubMed

Pick De Weiss, S

1995-01-01

The Institute Mexicano de Investigacion de Familia y Poblacion, A.C. (IMIFAP) tested the effectiveness of a training course and educational materials that were designed to increase the awareness and knowledge of pharmacy employees concerning acquired immunodeficiency syndrome (AIDS) and its prevention, and to promote condoms. 174 employees participated in workshops that included information on transmission and prevention of sexually transmitted diseases (STDs) and AIDS, and condom usage. Pre- and post-session tests were performed to ascertain the short-term retention of information; the long-term effect was assessed via incognito shopper visits and monitoring of condom sales. Short, intensive training, when reinforced by posters, pamphlets, and video, significantly increased knowledge of AIDS (symptoms, transmission, and prevention) and correct condom usage. Awareness of risk behaviors and groups at risk for AIDS improved. Printed materials alone did not have a substantial impact on knowledge or sales of condoms, and increased knowledge alone did not increase information disseminated. After 6 months there was a significantly higher rise in condom sales (16%) in the course-plus-materials group. This group also took a greater initiative in providing information to clients. In spite of these positive results, knowledge and initiative are still unsatisfactory, especially when the role of pharmacies in general health care and the suspected prevalence of sexually transmitted diseases and human immunodeficiency virus in Mexico are considered.

Characterization and metrology implications of the 1997 NTRS

NASA Astrophysics Data System (ADS)

Class, W.; Wortman, J. J.

1998-11-01

In the Front-end (transistor forming) area of silicon CMOS device processing, several NTRS difficult challenges have been identified including; scaled and alternate gate dielectric materials, new DRAM dielectric materials, alternate gate materials, elevated contact structures, engineered channels, and large-area cost-effective silicon substrates. This paper deals with some of the characterization and metrology challenges facing the industry if it is to meet the projected needs identified in the NTRS. In the areas of gate and DRAM dielectric, scaling requires that existing material layers be thinned to maximize capacitance. For the current gate dielectric, SiO2 and its nitrided derivatives, direct tunneling will limit scaling to approximately 1.5nm for logic applications before power losses become unacceptable. Low power logic and memory applications may limit scaling to the 2.0-2.2nm range. Beyond these limits, dielectric materials having higher dielectric constant, will permit continued capacitance increases while allowing for the use of thicker dielectric layers, where tunneling may be minimized. In the near term silicon nitride is a promising SiO2 substitute material while in the longer term "high-k" materials such as tantalum pentoxide and barium strontium titanate (BST) will be required. For these latter materials, it is likely that a multilayer dielectric stack will be needed, consisting of an ultra-thin (1-2 atom layer) interfacial SiO2 layer and a high-k overlayer. Silicon wafer surface preparation control, as well as the control of composition, crystal structure, and thickness for such stacks pose significant characterization and metrology challenges. In addition to the need for new gate dielectric materials, new gate materials will be required to overcome the limitations of the current doped polysilicon gate materials. Such a change has broad ramifications on device electrical performance and manufacturing process robustness which again implies a broad range of new characterization and metrology requirements. Finally, the doped structure of the MOS transistor must scale to very small lateral and depth dimensions, and thermal budgets must be reduced to permit the retention of very abrupt highly doped drain and channel engineered structures. Eventually, the NTRS forecasts the need for an elevated contact structure. Here, there are significant challenges associated with three-dimensional dopant profiling, measurement of dopant activity in ultra-shallow device regions, as well as point defect metrology and characterization.

Global financial crisis and weak-form efficiency of Islamic sectoral stock markets: An MF-DFA analysis

NASA Astrophysics Data System (ADS)

Mensi, Walid; Tiwari, Aviral Kumar; Yoon, Seong-Min

2017-04-01

This paper estimates the weak-form efficiency of Islamic stock markets using 10 sectoral stock indices (basic materials, consumer services, consumer goods, energy, financials, health care, industrials, technology, telecommunication, and utilities). The results based on the multifractal detrended fluctuation analysis (MF-DFA) approach show time-varying efficiency for the sectoral stock markets. Moreover, we find that they tend to show high efficiency in the long term but moderate efficiency in the short term, and that these markets become less efficient after the onset of the global financial crisis. These results have several significant implications in terms of asset allocation for investors dealing with Islamic markets.

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

Howell, Caitlin; Vu, Thy L.; Lin, Jennifer J.

Inspired by the long-term effectiveness of living antifouling materials, we have developed a method for the selfreplenishment of synthetic biofouling-release surfaces. These surfaces are created by either molding or directly embedding 3D vascular systems into polydimethylsiloxane (PDMS) and filling them with a silicone oil to generate a nontoxic oil-infused material. When replenished with silicone oil from an outside source, these materials are capable of self-lubrication and continuous renewal of the interfacial fouling-release layer. Under accelerated lubricant loss conditions, fully infused vascularized samples retained significantly more lubricant than equivalent nonvascularized controls. Tests of lubricant-infused PDMS in static cultures of the infectiousmore » bacteria Staphylococcus aureus and Escherichia coli as well as the green microalgae Botryococcus braunii, Chlamydomonas reinhardtii, Dunaliella salina, and Nannochloropsis oculata showed a significant reduction in biofilm adhesion compared to PDMS and glass controls containing no lubricant. Further experiments on vascularized versus nonvascularized samples that had been subjected to accelerated lubricant evaporation conditions for up to 48 h showed significantly less biofilm adherence on the vascularized surfaces. These results demonstrate the ability of an embedded lubricant-filled vascular network to improve the longevity of fouling-release surfaces.« less

Phosphate-bonded ceramic–wood composites : R&D project overview and invitation to participate

Treesearch

Theodore L. Laufenberg; Matt Aro

2004-01-01

We are developing chemically bonded ceramic phosphate binders for the production of biofiber-based composite materials. These binders promise to have better processing and properties than some current cement and polymer resin binder systems. The ceramic phosphate binders (termed Ceramicrete), if used in place of cement and polymers, will significantly reduce the...

Improved Durability of SOEC Stacks for High Temperature Electrolysis

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

James E. O'Brien; Robert C. O'Brien; Xiaoyu Zhang

2013-01-01

High temperature steam electrolysis is a promising technology for efficient and sustainable large-scale hydrogen production. Solid oxide electrolysis cells (SOECs) are able to utilize high temperature heat and electric power from advanced high-temperature nuclear reactors or renewable sources to generate carbon-free hydrogen at large scale. However, long term durability of SOECs needs to be improved significantly before commercialization of this technology can be realized. A degradation rate of 1%/khr or lower is proposed as a threshold value for commercialization of this technology. Solid oxide electrolysis stack tests have been conducted at Idaho National Laboratory to demonstrate recent improvements in long-termmore » durability of SOECs. Electrolyte-supported and electrode-supported SOEC stacks were provided by Ceramatec Inc. and Materials and Systems Research Inc. (MSRI), respectively, for these tests. Long-term durability tests were generally operated for a duration of 1000 hours or more. Stack tests based on technologies developed at Ceramatec and MSRI have shown significant improvement in durability in the electrolysis mode. Long-term degradation rates of 3.2%/khr and 4.6%/khr were observed for MSRI and Ceramatec stacks, espectively. One recent Ceramatec stack even showed negative degradation (performance improvement) over 1900 hours of operation. Optimization of electrode materials, interconnect coatings, and electrolyte-electrode interface microstructures contribute to better durability of SOEC stacks.« less

Measurements of Electrical and Electron Emission Properties of Highly Insulating Materials

NASA Technical Reports Server (NTRS)

Dennison, J. R.; Brunson, Jerilyn; Hoffman, Ryan; Abbott, Jonathon; Thomson, Clint; Sim, Alec

2005-01-01

Highly insulating materials often acquire significant charges when subjected to fluxes of electrons, ions, or photons. This charge can significantly modify the materials properties of the materials and have profound effects on the functionality of the materials in a variety of applications. These include charging of spacecraft materials due to interactions with the severe space environment, enhanced contamination due to charging in Lunar of Martian environments, high power arching of cables and sources, modification of tethers and ion thrusters for propulsion, and scanning electron microscopy, to name but a few examples. This paper describes new techniques and measurements of the electron emission properties and resistivity of highly insulating materials. Electron yields are a measure of the number of electrons emitted from a material per incident particle (electron, ion or photon). Electron yields depend on incident species, energy and angle, and on the material. They determine the net charge acquired by a material subject to a give incident flu. New pulsed-beam techniques will be described that allow accurate measurement of the yields for uncharged insulators and measurements of how the yields are modified as charge builds up in the insulator. A key parameter in modeling charge dissipation is the resistivity of insulating materials. This determines how charge will accumulate and redistribute across an insulator, as well as the time scale for charge transport and dissipation. Comparison of new long term constant-voltage methods and charge storage methods for measuring resistivity of highly insulating materials will be compared to more commonly used, but less accurate methods.

Multicriteria Decision Analysis of Material Selection of High Energy Performance Residential Building

NASA Astrophysics Data System (ADS)

Čuláková, Monika; Vilčeková, Silvia; Katunská, Jana; Krídlová Burdová, Eva

2013-11-01

In world with limited amount of energy sources and with serious environmental pollution, interest in comparing the environmental embodied impacts of buildings using different structure systems and alternative building materials will be increased. This paper shows the significance of life cycle energy and carbon perspective and the material selection in reducing energy consumption and emissions production in the built environment. The study evaluates embodied environmental impacts of nearly zero energy residential structures. The environmental assessment uses framework of LCA within boundary: cradle to gate. Designed alternative scenarios of material compositions are also assessed in terms of energy effectiveness through selected thermal-physical parameters. This study uses multi-criteria decision analysis for making clearer selection between alternative scenarios. The results of MCDA show that alternative E from materials on nature plant base (wood, straw bales, massive wood panel) present possible way to sustainable perspective of nearly zero energy houses in Slovak republic

Lack of Comprehension of Common Prostate Cancer Terms in an Underserved Population

PubMed Central

Kilbridge, Kerry L.; Fraser, Gertrude; Krahn, Murray; Nelson, Elizabeth M.; Conaway, Mark; Bashore, Randall; Wolf, Andrew; Barry, Michael J.; Gong, Debra A.; Nease, Robert F.; Connors, Alfred F.

2009-01-01

Purpose To assess the comprehension of common medical terms used in prostate cancer in patient education materials to obtain informed consent, and to measure outcomes after prostate cancer treatment. We address this issue among underserved, African-American men because of the increased cancer incidence and mortality observed in this population. Patients and Methods We reviewed patient education materials and prostate-specific quality-of-life instruments to identify technical terms describing sexual, urinary, and bowel function. Understanding of these terms was assessed in face-to-face interviews of 105, mostly African-American men, age ≥ 40, from two low-income clinics. Comprehension was evaluated using semiqualitative methods coded by two independent investigators. Demographics were collected and literacy was measured. Results Fewer than 50% of patients understood the terms “erection” or “impotent.” Only 5% of patients understood the term “incontinence” and 25% understood the term “bowel habits.” More patients recognized word roots than related terms or compound words (eg, “rectum” v “rectal urgency,” “intercourse” v “vaginal intercourse”). Comprehension of terms from all domains was statistically significantly correlated with reading level (P < .001). Median literacy level was fourth to sixth grade. Prostate cancer knowledge was poor. Many patients had difficulty locating key anatomic structures. Conclusion Limited comprehension of prostate cancer terms and low literacy create barriers to obtaining informed consent for treatment and to measuring prostate cancer outcomes accurately in our study population. In addition, the level of prostate cancer knowledge was poor. These results highlight the need for prostate cancer education efforts and outcomes measurements that consider literacy and use nonmedical language. PMID:19307512

Measuring stereoscopic image quality experience with interpretation based quality methodology

NASA Astrophysics Data System (ADS)

Häkkinen, Jukka; Kawai, Takashi; Takatalo, Jari; Leisti, Tuomas; Radun, Jenni; Hirsaho, Anni; Nyman, Göte

2008-01-01

Stereoscopic technologies have developed significantly in recent years. These advances require also more understanding of the experiental dimensions of stereoscopic contents. In this article we describe experiments in which we explore the experiences that viewers have when they view stereoscopic contents. We used eight different contents that were shown to the participants in a paired comparison experiment where the task of the participants was to compare the same content in stereoscopic and non-stereoscopic form. The participants indicated their preference but were also interviewed about the arguments they used when making the decision. By conducting a qualitative analysis of the interview texts we categorized the significant experiental factors related to viewing stereoscopic material. Our results indicate that reality-likeness as well as artificiality were often used as arguments in comparing the stereoscopic materials. Also, there were more emotional terms in the descriptions of the stereoscopic films, which might indicate that the stereoscopic projection technique enhances the emotions conveyed by the film material. Finally, the participants indicated that the three-dimensional material required longer presentation time, as there were more interesting details to see.

Uranium-233 waste definition: Disposal options, safeguards, criticality control, and arms control

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

Forsberg, C.W.; Storch, S.N.; Lewis, L.C.

1998-07-07

The US investigated the use of {sup 233}U for weapons, reactors, and other purposes from the 1950s into the 1970s. Based on the results of these investigations, it was decided not to use {sup 233}U on a large scale. Most of the {sup 233}U-containing materials were placed in long-term storage. At the end of the cold war, the US initiated, as part of its arms control policies, a disposition program for excess fissile materials. Other programs were accelerated for disposal of radioactive wastes placed in storage during the cold war. Last, potential safety issues were identified related to the storagemore » of some {sup 233}U-containing materials. Because of these changes, significant activities associated with {sup 233}U-containing materials are expected. This report is one of a series of reports to provide the technical bases for future decisions on how to manage this material. A basis for defining when {sup 233}U-containing materials can be managed as waste and when they must be managed as concentrated fissile materials has been developed. The requirements for storage, transport, and disposal of radioactive wastes are significantly different than those for fissile materials. Because of these differences, it is important to classify material in its appropriate category. The establishment of a definition of what is waste and what is fissile material will provide the guidance for appropriate management of these materials. Wastes are defined in this report as materials containing sufficiently small masses or low concentrations of fissile materials such that they can be managed as typical radioactive waste. Concentrated fissile materials are defined herein as materials containing sufficient fissile content such as to warrant special handling to address nuclear criticality, safeguards, and arms control concerns.« less

Effects of packaging materials on storage quality of peanut kernels

PubMed Central

Fu, Xiaoji; Xing, Shengping; Xiong, Huiwei; Min, Hua; Zhu, Xuejing; He, Jialin; Mu, Honglei

2018-01-01

In order to obtain optimum packaging materials for peanut kernels, the effects of four types of packaging materials on peanut storage quality (coat color, acid value, germination rate, relative damage, and prevention of aflatoxin contamination) were examined. The results showed that packaging materials had a major influence on peanut storage quality indexes. The color of the peanut seed coat packaged in the polyester/aluminum/polyamide/polyethylene (PET/AL/PA/PE) composite film bag did not change significantly during the storage period. Color deterioration was slower with polyamide/polyethylene (PA/PE) packaging materials than with polyethylene (PE) film bags and was slower in PE bags than in the woven bags. The use of PET/AL/PA/PE and PA/PE bags maintained peanut quality and freshness for more than one year and both package types resulted in better germination rates. There were significant differences between the four types of packaging materials in terms of controlling insect pests. The peanuts packaged in the highly permeable woven bags suffered serious invasion from insect pests, while both PET/AL/PA/PE and PA/PE bags effectively prevented insect infection. Peanuts stored in PET/AL/PA/PE and PA/PE bags were also better at preventing and controlling aflatoxin contamination. PMID:29518085

Evaluation and prediction of long-term environmental effects on nonmetallic materials

NASA Technical Reports Server (NTRS)

1982-01-01

Changes in functional properties of a broad spectrum of nonmetallic materials as a function of environment and exposure time were evaluated. Models for predicting long-term material performance are discussed. A literature search on specific materials in the space and simulated space environment was carried out and evaluated.

Comparing the short and long term stability of biodegradable, ceramic and cation exchange membranes in microbial fuel cells.

PubMed

Winfield, Jonathan; Chambers, Lily D; Rossiter, Jonathan; Ieropoulos, Ioannis

2013-11-01

The long and short-term stability of two porous dependent ion exchange materials; starch-based compostable bags (BioBag) and ceramic, were compared to commercially available cation exchange membrane (CEM) in microbial fuel cells. Using bi-directional polarisation methods, CEM exhibited power overshoot during the forward sweep followed by significant power decline over the reverse sweep (38%). The porous membranes displayed no power overshoot with comparably smaller drops in power during the reverse sweep (ceramic 8%, BioBag 5.5%). The total internal resistance at maximum power increased by 64% for CEM compared to 4% (ceramic) and 6% (BioBag). Under fixed external resistive loads, CEM exhibited steeper pH reductions than the porous membranes. Despite its limited lifetime, the BioBag proved an efficient material for a stable microbial environment until failing after 8 months, due to natural degradation. These findings highlight porous separators as ideal candidates for advancing MFC technology in terms of cost and operation stability. Copyright © 2013 Elsevier Ltd. All rights reserved.

Measure Guideline: Guidance on Taped Insulating Sheathing Drainage Planes

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

Grin, A.; Lstiburek, J.

The goal of this research is to provide durable and long-term water management solutions using exterior insulating sheathing as part of the water management system. It is possible to tape or seal the joints in insulating sheathing to create a drainage plane and even an air control layer. There exists the material durability component of the tape as well as the system durability component being the taped insulating sheathing as the drainage plane. This measure guideline provides best practice and product recommendations from the interviewed contractors and homebuilders who collectively have a vast amount of experience. Three significant issues weremore » discussed with the group, which are required to make taped insulating sheathing a simple, long-term, and durable drainage plane: horizontal joints should be limited or eliminated wherever possible; where a horizontal joint exists use superior materials; and frequent installation inspection and regular trade training are required to maintain proper installation.« less

Application of Deep Cryogenic Treatment to Uncoated Tungsten Carbide Inserts in the Turning of AISI 304 Stainless Steel

NASA Astrophysics Data System (ADS)

Özbek, Nursel Altan; Çİçek, Adem; Gülesİn, Mahmut; Özbek, Onur

2016-12-01

This study investigated the effects of deep cryogenic treatment (DCT) on the wear performance of uncoated tungsten carbide inserts. AISI 304 austenitic stainless steel, widely used in industry, was selected as the workpiece material. Cutting experiments showed that the amount of wear significantly increased with increasing cutting speed. In addition, it was found that DCT contributed to the wear resistance of the turning inserts. The treated turning inserts were less worn by 48 and 38 pct in terms of crater wear and notch wear, respectively, whereas they exhibited up to 18 pct superior wear performance in terms of flank wear. This was attributed to the precipitation of new and finer η-carbides and their homogeneous distribution in the microstructure of the tungsten carbide material after deep cryogenic treatment. Analyses via image processing, hardness measurements, and SEM observations confirmed these findings.

Mechanical properties of a new mica-based machinable glass ceramic for CAD/CAM restorations.

PubMed

Thompson, J Y; Bayne, S C; Heymann, H O

1996-12-01

Machinable ceramics (Vita Mark II and Dicor MGC) exhibit good short-term clinical performance, but long-term in vivo fracture resistance is still being monitored. The relatively low fracture toughness of currently available machinable ceramics restricts their use to conservative inlays and onlays. A new machinable glass ceramic (MGC-F) has been developed (Corning Inc.) with enhanced fluorescence and machinability. The purpose of this study was to characterize and compare key mechanical properties of MGC-F to Dicor MGC-Light, Dicor MGC-Dark, and Vita Mark II glass ceramics. The mean fracture toughness and indented biaxial flexure strength of MGC-F were each significantly greater (p < or = 0.01) than that of Dicor MGC-Light, Dicor MGC-Dark, and Vita Mark II ceramic materials. The results of this study indicate the potential for better in vivo fracture resistance of MGC-F compared with existing machinable ceramic materials for CAD/CAM restorations.

PEMFC MEA and System Design Considerations

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

Knights, Shanna; Bashyam, Rajesh; He, Ping

2011-07-01

Proton exchange membrane fuel cells (PEMFCs) are being developed and sold commercially for multiple near term markets. Ballard Power Systems is focused on the near term markets of backup power, distributed generation, materials handling, and buses. Significant advances have been made in cost and durability of fuel cell products. Improved tolerance to a wide range of system operation and environmental noises will enable increased viability across a broad range of applications. In order to apply the most effective membrane electrode assembly (MEA) design for each market, the system requirements and associated MEA failures must be well understood. The failure modesmore » associated with the electrodes and membrane degradation are discussed with respect to associated system operation and mitigating approaches. A few key system considerations that influence MEA design include expected fuel quality, balance-of-plant materials, time under idle or open circuit operation, and start-up and shut-down conditions.« less

Descriptive Morphology Terms For MAMA software

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

Ruggiero, Christy E.; Porter, Reid B.

The table on the following pages lists a set of morphology terms for describing materials. We have organized these terms by categories. Software uses are welcome to suggest other terms that are needed to accurately describe materials. This list is intended as a initial starting point to generating a consensus terminology list.

Water sorption and solubility of polyamide denture base materials

PubMed Central

Nguyen, Long G.; Kopperud, Hilde M.; Øilo, Marit

2017-01-01

Abstract Purpose: Some patients experience adverse reactions to poly(methyl methacrylate)-based (PMMA) dentures. Polyamide (PA) as an alternative to PMMA has, however, not been well documented with regard to water sorption and water solubility. The aim of this in vitro study was to measure water sorption and water solubility of two PA materials compared with PMMA, and to evaluate the major components released from the PA materials and the effect on hardness of the materials. Methods: Ten discs (40.0 mm diameter, 2.0 mm thick) of each material (PA: Valplast and Breflex; PMMA: SR Ivocap HIP) were prepared according to manufacturers’ recommendations. The specimens were tested for water sorption and water solubility, according to a modification of ISO 20795-1:2008. Released substances were analysed by gas chromatography/mass spectrometry (GC/MS). Results: There were statistically significant differences among the materials regarding water sorption, water solubility and time to water saturation. Breflex had the highest water sorption (30.4 μg/mm3), followed by PMMA-material (25.8 μg/mm3) and Valplast (13.6 μg/mm3). Both PA materials had statistically significant lower water solubility than the PMMA. Both PA had a net increase in weight. Analysis by GC/MS identified release of the compound 12-aminododecanolactam from the material Valplast. No release was found from the Breflex material. Conclusions: The PA denture materials show differences in water sorption and solubility, but within the limits of the standard requirements. The PA showed a net increase in weight after long-term water sorption. The clinical implications of the findings are not elucidated. PMID:28642931

Water sorption and solubility of polyamide denture base materials.

PubMed

Nguyen, Long G; Kopperud, Hilde M; Øilo, Marit

2017-01-01

Purpose: Some patients experience adverse reactions to poly(methyl methacrylate)-based (PMMA) dentures. Polyamide (PA) as an alternative to PMMA has, however, not been well documented with regard to water sorption and water solubility. The aim of this in vitro study was to measure water sorption and water solubility of two PA materials compared with PMMA, and to evaluate the major components released from the PA materials and the effect on hardness of the materials. Methods: Ten discs (40.0 mm diameter, 2.0 mm thick) of each material (PA: Valplast and Breflex; PMMA: SR Ivocap HIP) were prepared according to manufacturers' recommendations. The specimens were tested for water sorption and water solubility, according to a modification of ISO 20795-1:2008. Released substances were analysed by gas chromatography/mass spectrometry (GC/MS). Results: There were statistically significant differences among the materials regarding water sorption, water solubility and time to water saturation. Breflex had the highest water sorption (30.4 μg/mm 3 ), followed by PMMA-material (25.8 μg/mm 3 ) and Valplast (13.6 μg/mm 3 ). Both PA materials had statistically significant lower water solubility than the PMMA. Both PA had a net increase in weight. Analysis by GC/MS identified release of the compound 12-aminododecanolactam from the material Valplast. No release was found from the Breflex material. Conclusions: The PA denture materials show differences in water sorption and solubility, but within the limits of the standard requirements. The PA showed a net increase in weight after long-term water sorption. The clinical implications of the findings are not elucidated.

Molecular analysis of long-term biofilm formation on PVC and cast iron surfaces in drinking water distribution system.

PubMed

Liu, Ruyin; Zhu, Junge; Yu, Zhisheng; Joshi, DevRaj; Zhang, Hongxun; Lin, Wenfang; Yang, Min

2014-04-01

To understand the impacts of different plumbing materials on long-term biofilm formation in water supply system, we analyzed microbial community compositions in the bulk water and biofilms on faucets with two different materials-polyvinyl chloride (PVC) and cast iron, which have been frequently used for more than10 years. Pyrosequencing was employed to describe both bacterial and eukaryotic microbial compositions. Bacterial communities in the bulk water and biofilm samples were significantly different from each other. Specific bacterial populations colonized on the surface of different materials. Hyphomicrobia and corrosion associated bacteria, such as Acidithiobacillus spp., Aquabacterium spp., Limnobacter thiooxidans, and Thiocapsa spp., were the most dominant bacteria identified in the PVC and cast iron biofilms, respectively, suggesting that bacterial colonization on the material surfaces was selective. Mycobacteria and Legionella spp. were common potential pathogenic bacteria occurred in the biofilm samples, but their abundance was different in the two biofilm bacterial communities. In contrast, the biofilm samples showed more similar eukaryotic communities than the bulk water. Notably, potential pathogenic fungi, i.e., Aspergillus spp. and Candida parapsilosis, occurred in similar abundance in both biofilms. These results indicated that microbial community, especially bacterial composition was remarkably affected by the different pipe materials (PVC and cast iron). Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Interventions aimed at reducing obesity in early childhood: a meta-analysis of programs that involve parents.

PubMed

Yavuz, H Melis; van Ijzendoorn, Marinus H; Mesman, Judi; van der Veek, Shelley

2015-06-01

Obesity is a growing problem even in very young childhood, resulting in high costs for individuals and society. As a response, numerous obesity prevention and intervention programs have been developed. Previous research has shown that early intervention programs are more effective when parents are involved, but the effectiveness of specific aspects of programs with parental involvement has not been investigated. This meta-analysis aims to investigate the features related to the effectiveness of different types of obesity intervention programs involving parents and targeting young children (0-6-year-olds). The Web of Science, PubMed, PsycInfo, CINAHL, and ERIC databases were searched for childhood obesity prevention and intervention programs involving parents. Data were analyzed using the Comprehensive Meta-analysis (CMA) software. Fifty studies with effect sizes measured at short-term follow-up (within 3 months from the end of the intervention) and 26 studies with effect sizes measured at long-term follow-up (all reported in a total of 49 publications) were identified. The combined effect size of interventions was small but significant at short-term follow-up (d = .08, p < .01). The results suggested the presence of a potential publication bias in studies providing results at long-term follow-up, with a nonsignificant adjusted effect size (d = .02), which indicated that obesity interventions were not effective at long-term follow-up. Multivariate meta-regression analyses showed that interventions were more effective when including either interactive sessions or educational materials as opposed to those including both interactive sessions and noninteractive educational materials. No other moderators regarding sample characteristics, study design, or methodological quality were significant. Interventions targeting young children that require parental involvement are effective at short-term follow-up, specifically when interventions include one mode of intervention rather than two. However, results were not retained in the long run. © 2014 Association for Child and Adolescent Mental Health.

Free recall in Williams syndrome: is there a dissociation between short- and long-term memory?

PubMed

Brock, Jon; Brown, Gordon D A; Boucher, Jill

2006-04-01

Two experiments used the free recall paradigm to investigate verbal memory abilities in Williams syndrome (WS)--a rare genetic disorder. In an earlier free recall study, Vicari et al. (1996a) reported that, unlike TD controls, children with WS showed a recency effect but failed to show a primacy effect. These authors interpreted their findings as evidence for a dissociation between relatively strong verbal short-term memory and relatively impaired verbal long-term memory. In Experiment 1 of the current study, children with WS and TD controls showed comparable improvements in performance with repeated testing of the same material, indicating similar long-term learning of the test items. Neither group showed evidence of primacy effects. However, the extent of primacy effects in free recall is known to depend on the rehearsal strategy that participants adopt. In Experiment 2, therefore, participants were encouraged to engage in overt cumulative rehearsal. This manipulation resulted in significant and comparable primacy effects in both groups, although neither group demonstrated a significant change in overall performance. There was therefore no evidence from either experiment for a dissociation between short- and long-term verbal memory in WS.

SSME main combustion chamber life prediction

NASA Technical Reports Server (NTRS)

Cook, R. T.; Fryk, E. E.; Newell, J. F.

1983-01-01

Typically, low cycle fatigue life is a function of the cyclic strain range, the material properties, and the operating temperature. The reusable life is normally defined by the number of strain cycles that can be accrued before severe material degradation occurs. Reusable life is normally signified by the initiation or propagation of surface cracks. Hot-fire testing of channel wall combustors has shown significant mid-channel wall thinning or deformation during accrued cyclic testing. This phenomenon is termed cyclic-creep and appears to be significantly accelerated at elevated surface temperatures. This failure mode was analytically modelled. The cyclic life of the baseline SSME-MCC based on measured calorimeter heat transfer data, and the life sensitivity of local hot spots caused by injector effects were determined. Four life enhanced designs were assessed.

Material from the Internal Surface of Squid Axon Exhibits Excess Noise

PubMed Central

Fishman, Harvey M.

1981-01-01

A fluid material from a squid (Loligo pealei) axon was isolated by mechanical application of two types of microcapillary (1-3-μm Diam) to the internal surface of intact and cut-axon preparations. Current noise in the isolated material exceeded thermal levels and power spectra were 1/f in form in the frequency range 1.25-500 Hz with voltage-dependent intensities that were unrelated to specific ion channels. Whether conduction in this material is a significant source of excess noise during axon conduction remains to be determined. Nevertheless, a source of excess noise external to or within an ion channel may not be properly represented solely as an additive term to the spectrum of ion channel noise; a deconvolution of these spectral components may be required for modeling purposes. PMID:6266542

Finite element analysis of fretting contact for nonhomogenous materials

NASA Astrophysics Data System (ADS)

Korkmaz, Y. M.; Coker, D.

2018-01-01

Fretting problem arises in the case of relatively small sliding motion between contacting surfaces. Fatigue life of the components that are in contact with each other, especially in rotorcraft may be significantly reduced due to fretting. The purpose of this study is to investigate material inhomogeneity near the contact region on the fretting problem in a cylindrical on flat contact configuration. A finite element (FE) model was constructed by using commercial finite element package ABAQUSTMto study partial sliding and stress concentrations. In order to investigate the effect of material inhomogeneity, the fretting contact is analyzed by introducing voids near the contact region. The void size and an array of voids is introduced into the substrate. The results are compared in terms of pressure, shear traction, tangential stress magnitudes and relative slip between the contacting materials.

Analysis of the embodied and operational energy: Study of a suburban house in Athens, Greece

NASA Astrophysics Data System (ADS)

Ghiata, Maria

Operational energy can establish how successful a building is, in terms of environmentally 'considerate' design. Though embodied energy of construction materials also comprises an important indicator of the environmental impact of the material, the construction industry does not really promote it as such. This report enhances the significance of embodied energy and its relationship to operational energy (energy in use). Since buildings are becoming less energy demanding, operational energy will be decreasing, so that embodied energy will be gaining ground in the attempt to protect the environment. By the use of an 'environmentally friendly' house as a case study, it was proven that, though changes of the wall, floor, and insulation materials can take place, the operational energy does not change. What is greatly affected is the embodied energy of these construction materials.

Cosmochemistry: Understanding the Solar System through analysis of extraterrestrial materials.

PubMed

MacPherson, Glenn J; Thiemens, Mark H

2011-11-29

Cosmochemistry is the chemical analysis of extraterrestrial materials. This term generally is taken to mean laboratory analysis, which is the cosmochemistry gold standard because of the ability for repeated analysis under highly controlled conditions using the most advanced instrumentation unhindered by limitations in power, space, or environment. Over the past 40 y, advances in technology have enabled telescopic and spacecraft instruments to provide important data that significantly complement the laboratory data. In this special edition, recent advances in the state of the art of cosmochemistry are presented, which range from instrumental analysis of meteorites to theoretical-computational and astronomical observations.

Environmental profile evaluations of piezoelectric polymers using life cycle assessment

NASA Astrophysics Data System (ADS)

Parvez Mahmud, M. A.; Huda, Nazmul; Hisan Farjana, Shahjadi; Lang, Candace

2018-05-01

Piezoelectric materials are indispensable to produce electricity, harvesting ambient mechanical energy through motion for sectors and products, from sensors, to biomedical systems, to tiny electronics. Nylon 66 and tetrafluoroethylene dominate the market among thousands of piezoelectric materials to provide an autonomous power supply. Emphasis has been given on investigating the environmental impacts of both materials due to the growing consciousness of the ecological and health risks of piezoelectric polymers. The fabrication steps of these polymers from raw materials are extremely hazardous to the environment in terms of toxicity and human health effects. However, no quantification of the possible environmental impacts for the manufacturing of nylon 66 and tetrafluoroethylene exists. This research paper addresses their comparative environmental effects, in terms of chemical constituents. Life cycle impact analysis has been carried out by ReCipe 2016 Endpoint, Ecopoints 97, Raw material flows and CML-IA baseline methods, using Australasian life cycle inventory database and SimaPro software. The impacts are considered in categories like global warming, eutrophication, terrestrial ecotoxicity, human carcinogenic toxicity, fine particulates, and marine ecotoxicity. The results show that there is a significant environmental impact caused by tetrafluoroethylene in comparison with nylon 66 polymer during the manufacturing process. These impacts occur due to the quantity of toxic chemical elements present as constituents of tetrafluoroethylene raw material and its fabrication periods. It can be anticipated that a better ecological performance can be attained through optimization, especially by cautiously picking substitute materials and machines, taking into account the toxicity aspects, and by minimizing the impacts related to designs, fabrication processes and usage.

Dielectric Characteristics of Microstructural Changes and Property Evolution in Engineered Materials

NASA Astrophysics Data System (ADS)

Clifford, Jallisa Janet

Heterogeneous materials are increasingly used in a wide range of applications such as aerospace, civil infrastructure, fuel cells and many others. The ability to take properties from two or more materials to create a material with properties engineered to needs is always very attractive. Hence heterogeneous materials are evolving into more complex formulations in multiple disciplines. Design of microstructure at multiple scales control the global functional properties of these materials and their structures. However, local microstructural changes do not directly cause a proportional change to the global properties (such as strength and stiffness). Instead, local changes follow an evolution process including significant interactions. Therefore, in order to understand property evolution of engineered materials, microstructural changes need to be effectively captured. Characterizing these changes and representing them by material variables will enable us to further improve our material level understanding. In this work, we will demonstrate how microstructural features of heterogeneous materials can be described quantitatively using broadband dielectric spectroscopy (BbDS). The frequency dependent dielectric properties can capture the change in material microstructure and represent these changes in terms of material variables, such as complex permittivity. These changes in terms of material properties can then be linked to a number of different conditions, such as increasing damage due to impact or fatigue. Two different broadband dielectric spectroscopy scanning modes are presented: bulk measurements and continuous scanning to measure dielectric property change as a function of position across the specimen. In this study, we will focus on ceramic materials and fiber reinforced polymer matrix composites as test bed material systems. In the first part of the thesis, we will present how different micro-structural design of porous ceramic materials can be captured quantitatively using BbDS. These materials are typically used in solid oxide fuel cells (SOFC). Results show significant effect of microstructural design on material properties at multiple temperatures (up to 800 °C). In the later part of the thesis, we will focus on microstructural changes of fiber reinforced composite materials due to impact and static loading. The changes in dielectric response can then be linked to the bulk mechanical properties of the material and various damage modes. Observing trends in dielectric response enables us to further determine local mechanisms and distribution of properties throughout the damaged specimens. A 3D X-ray microscope and a digital microscope have been used to visualize these changes in material microstructure and validate experimental observations. The increase in damage observed in the material microstructure can then also be linked to the changes in dielectric response. Results show that BbDS is an extremely useful tool for identifying microstructural changes within a heterogeneous material and particularly useful in relating remaining properties. Dielectric material variables can be used directly in property degradation laws and help develop a framework for future predictive modeling methodologies.

A laser-engraved glass duplicating the structure, mechanics and performance of natural nacre.

PubMed

Valashani, Seyed Mohammad Mirkhalaf; Barthelat, Francois

2015-03-30

Highly mineralized biological materials such as nacre (mother of pearl), tooth enamel or conch shell boast unique and attractive combinations of stiffness, strength and toughness. The structures of these biological materials and their associated mechanisms are now inspiring new types of advanced structural materials. However, despite significant efforts, no bottom up fabrication method could so far match biological materials in terms of microstructural organization and mechanical performance. Here we present a new 'top down' strategy to tackling this fabrication problem, which consists in carving weak interfaces within a brittle material using a laser engraving technique. We demonstrate the method by fabricating and testing borosilicate glasses containing nacre-like microstructures infiltrated with polyurethane. When deformed, these materials properly duplicate the mechanisms of natural nacre: combination of controlled sliding of the tablets, accompanied with geometric hardening, strain hardening and strain rate hardening. The nacre-like glass is composed of 93 volume % (vol%) glass, yet 700 times tougher and breaks at strains as high as 20%.

Radiopacity of endodontic materials on film and a digital sensor.

PubMed

Rasimick, Brian J; Shah, Rinal P; Musikant, Barry Lee; Deutsch, Allan S

2007-09-01

The purpose of this study was to compare the radiographic appearance of 12 endodontic materials as visualized on either Kodak Ultra-speed D speed film (Eastman Kodak Company, Rochester, NY) or a Gendex eHD digital sensor (Gendex Dental Systems, Milan, Italy). Ten discs of each material were radiographed alongside an aluminum alloy 1100 (Alcoa, Pittsburgh, PA) stepwedge that was used for reference. For every radiograph, the average grayscale value of the material was converted into absorbance notation and compared with that of the reference stepwedge in order to determine the equivalent radiopacity in terms of millimeters of Al 1100 per millimeter of material. Two-way repeated-measures analysis of variance testing detected significant differences with respect to imaging system, material, and the interaction of the two factors (p < 0.001). The difference in a material's radiopacity as measured on the digital sensor compared with film was greater than 10% for 4 of the 12 materials and over 40% for InnoEndo (Heraus Kulzer, Armonk, NY). It was speculated that barium fillers cause this effect.

Semiconductor materials for high frequency solid state sources

NASA Astrophysics Data System (ADS)

Grubin, H. L.

1983-03-01

The broad goal of the subject contract is to suggest candidate materials for high frequency device operation. During the initial phase of the study, attention has been focused on defining the general role of the band structure and associated scattering processes in determining the response of semiconductors to transient high-speed electrical signals. Moments of the Boltzmann transport equation form the basis of the study, and the scattering rates define the semiconductor under study. The selection of semiconductor materials proceeds from a set of simple, yet significant, set of scaling principles. During the first quarter scaling was associated with what can formally be identified as velocity invariants, but which in more practical terms identifies the relative speed advantages of e.g., InP over GaAs.

From Cell to Module: Fabrication and Long-term Stability of Dye-sensitized Solar Cells

NASA Astrophysics Data System (ADS)

Nursam, N. M.; Hidayat, J.; Muliani, L.; Anggraeni, P. N.; Retnaningsih, L.; Idayanti, N.

2017-07-01

Dye-sensitized solar cell (DSSC), which has been firstly developed by Graetzel et al back in 1991, has attracted a considerable interest since its discovery. However, two of the main challenges that the DSSC technology will have to overcome towards commercialization involve device scale-up and long-term stability. In our group, the fabrication technology of DSSC has been developed from laboratory to module scale over the past few years, nevertheless, the long-term stability has still became a major concern. In this contribution, the long-term DSSC performance in relation to their scale-up from cell to module is investigated. The photoelectrode of the DSSCs were fabricated using nanocrystalline titanium dioxide materials that were subsequently sensitized using ruthenium-based dye. Additionally, TiCl4 pre- and post-treatment were carried out to enhance the overall device efficiency. When fabricated as cells, the DSSC prototypes showed relatively stable performance during repeated tests over three months. In order to increase the output power of the solar cells, the DSSCs were then connected in a Z-type series connection to obtain sub-module panels. The DSSC sub-modules exhibit poor stability, particularly as indicated by the significant decrease in the short circuit current (ISC ). Herein, the effect of photoelectrode and sealant materials as well as module design are investigated, highlighting their profound influence upon the DSSC efficiency and long-term stability.

Nitric oxide-releasing antibacterial albumin plastic for biomedical applications.

PubMed

Jones, Alexander; Pant, Jitendra; Lee, Eliza; Goudie, Marcus J; Gruzd, Alexey; Mansfield, Joel; Mandal, Abhyuday; Sharma, Suraj; Handa, Hitesh

2018-06-01

Designing innovative materials for biomedical applications is desired to prevent surface fouling and risk of associated infections arising in the surgical care patient. In the present study, albumin plastic was fabricated and nitric oxide (NO) donor, S-nitroso-N-acetylpenicillamine (SNAP), was incorporated through a solvent swelling process. The albumin-SNAP plastic was evaluated in terms of mechanical and thermal properties, and bacterial adhesion to the plastic surface. Thermal and viscoelastic analyses showed no significant difference between albumin-SNAP plastics and pure, water-plasticized albumin samples. Bacteria adhesion tests revealed that albumin-SNAP plastic can significantly reduce the surface-bound viable gram-positive Staphylococcus aureus and gram-negative Pseudomonas aeruginosa bacterial cells by 98.7 and 98.5%, respectively, when compared with the traditional polyvinyl chloride medical grade tubing material. The results from this study demonstrate NO-releasing albumin plastic's potential as a material for biomedical device applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1535-1542, 2018. © 2018 Wiley Periodicals, Inc.

Prediction of fracture toughness and durability of adhesively bonded composite joints with undesirable bonding conditions

NASA Astrophysics Data System (ADS)

Musaramthota, Vishal

Advanced composite materials have enabled the conventional aircraft structures to reduce weight, improve fuel efficiency and offer superior mechanical properties. In the past, materials such as aluminum, steel or titanium have been used to manufacture aircraft structures for support of heavy loads. Within the last decade or so, demand for advanced composite materials have been emerging that offer significant advantages over the traditional metallic materials. Of particular interest in the recent years, there has been an upsurge in scientific significance in the usage of adhesively bonded composite joints (ABCJ's). ABCJ's negate the introduction of stress risers that are associated with riveting or other classical techniques. In today's aircraft transportation market, there is a push to increase structural efficiency by promoting adhesive bonding to primary joining of aircraft structures. This research is focused on the issues associated with the durability and related failures in bonded composite joints that continue to be a critical hindrance to the universal acceptance of ABCJ's. Of particular interest are the short term strength, contamination and long term durability of ABCJ's. One of the factors that influence bond performance is contamination and in this study the influence of contamination on composite-adhesive bond quality was investigated through the development of a repeatable and scalable surface contamination procedure. Results showed an increase in the contaminant coverage area decreases the overall bond strength significantly. A direct correlation between the contaminant coverage area and the fracture toughness of the bonded joint was established. Another factor that influences bond performance during an aircraft's service life is its long term strength upon exposure to harsh environmental conditions or when subjected to severe mechanical loading. A test procedure was successfully developed in order to evaluate durability of ABCJ's comprising severe environmental conditioning, fatiguing in ambient air and a combination of both. The bonds produced were durable enough to sustain the tests cases mentioned above when conditioned for 8 weeks and did not experience any loss in strength. Specimens that were aged for 80 weeks showed a degradation of 10% in their fracture toughness when compared to their baseline datasets. The effect of various exposure times needs to be further evaluated to establish the relationship of durability that is associated with the fracture toughness of ABCJ's.

Compressive Properties and Anti-Erosion Characteristics of Foam Concrete in Road Engineering

NASA Astrophysics Data System (ADS)

Li, Jinzhu; Huang, Hongxiang; Wang, Wenjun; Ding, Yifan

2018-01-01

To analyse the compression properties and anti-erosion characteristics of foam concrete, one dimensional compression tests were carried out using ring specimens of foam concrete, and unconfined compression tests were carried out using foam concrete specimens cured in different conditions. The results of one dimensional compression tests show that the compression curve of foam concrete has two critical points and three stages, which has significant difference with ordinary geotechnical materials such as soil. Based on the compression curve the compression modulus of each stage were determined. The results of erosion tests show that sea water has a slight influence on the long-term strength of foam concrete, while the sulphate solution has a significant influence on the long-term strength of foam concrete, which needs to pay more attention.

Long-Term Effects of Multiwalled Carbon Nanotubes and Graphene on Microbial Communities in Dry Soil.

PubMed

Ge, Yuan; Priester, John H; Mortimer, Monika; Chang, Chong Hyun; Ji, Zhaoxia; Schimel, Joshua P; Holden, Patricia A

2016-04-05

Little is known about the long-term effects of engineered carbonaceous nanomaterials (ECNMs) on soil microbial communities, especially when compared to possible effects of natural or industrial carbonaceous materials. To address these issues, we exposed dry grassland soil for 1 year to 1 mg g(-1) of either natural nanostructured material (biochar), industrial carbon black, three types of multiwalled carbon nanotubes (MWCNTs), or graphene. Soil microbial biomass was assessed by substrate induced respiration and by extractable DNA. Bacterial and fungal communities were examined by terminal restriction fragment length polymorphism (T-RFLP). Microbial activity was assessed by soil basal respiration. At day 0, there was no treatment effect on soil DNA or T-RFLP profiles, indicating negligible interference between the amended materials and the methods for DNA extraction, quantification, and community analysis. After a 1-year exposure, compared to the no amendment control, some treatments reduced soil DNA (e.g., biochar, all three MWCNT types, and graphene; P < 0.05) and altered bacterial communities (e.g., biochar, carbon black, narrow MWCNTs, and graphene); however, there were no significant differences across the amended treatments. These findings suggest that ECNMs may moderately affect dry soil microbial communities but that the effects are similar to those from natural and industrial carbonaceous materials, even after 1-year exposure.

Development and Dematerialization: An International Study

PubMed Central

Steinberger, Julia K.; Krausmann, Fridolin; Getzner, Michael; Schandl, Heinz; West, Jim

2013-01-01

Economic development and growth depend on growing levels of resource use, and result in environmental impacts from large scale resource extraction and emissions of waste. In this study, we examine the resource dependency of economic activities over the past several decades for a set of countries comprising developing, emerging and mature industrialized economies. Rather than a single universal industrial development pathway, we find a diversity of economic dependencies on material use, made evident through cluster analysis. We conduct tests for relative and absolute decoupling of the economy from material use, and compare these with similar tests for decoupling from carbon emissions, both for single countries and country groupings using panel analysis. We show that, over the longer term, emerging and developing countries tend to have significantly larger material-economic coupling than mature industrialized economies (although this effect may be enhanced by trade patterns), but that the contrary is true for short-term coupling. Moreover, we demonstrate that absolute dematerialization limits economic growth rates, while the successful industrialization of developing countries inevitably requires a strong material component. Alternative development priorities are thus urgently needed both for mature and emerging economies: reducing absolute consumption levels for the former, and avoiding the trap of resource-intensive economic and human development for the latter. PMID:24204555

Evaluating environmental impacts of alternative construction waste management approaches using supply-chain-linked life-cycle analysis.

PubMed

Kucukvar, Murat; Egilmez, Gokhan; Tatari, Omer

2014-06-01

Waste management in construction is critical for the sustainable treatment of building-related construction and demolition (C&D) waste materials, and recycling of these wastes has been considered as one of the best strategies in minimization of C&D debris. However, recycling of C&D materials may not always be a feasible strategy for every waste type and therefore recycling and other waste treatment strategies should be supported by robust decision-making models. With the aim of assessing the net carbon, energy, and water footprints of C&D recycling and other waste management alternatives, a comprehensive economic input-output-based hybrid life-cycle assessment model is developed by tracing all of the economy-wide supply-chain impacts of three waste management strategies: recycling, landfilling, and incineration. Analysis results showed that only the recycling of construction materials provided positive environmental footprint savings in terms of carbon, energy, and water footprints. Incineration is a better option as a secondary strategy after recycling for water and energy footprint categories, whereas landfilling is found to be as slightly better strategy when carbon footprint is considered as the main focus of comparison. In terms of construction materials' environmental footprint, nonferrous metals are found to have a significant environmental footprint reduction potential if recycled. © The Author(s) 2014.

Explosive simulants for testing explosive detection systems

DOEpatents

Kury, John W.; Anderson, Brian L.

1999-09-28

Explosives simulants that include non-explosive components are disclosed that facilitate testing of equipment designed to remotely detect explosives. The simulants are non-explosive, non-hazardous materials that can be safely handled without any significant precautions. The simulants imitate real explosives in terms of mass density, effective atomic number, x-ray transmission properties, and physical form, including moldable plastics and emulsions/gels.

Method and Apparatus for Precisely Applying Large Planar Equi-Biaxial Strains to a Circular Membrane

DTIC Science & Technology

2013-04-01

potential future Army applications. Electronic properties, such as dielectric strength , capacitance, resistance, and inductance, vary significantly and... dielectric strength and resistance are primarily determined by inherent bulk material properties, including microstructure, while shifts in inductance...less and a nominal thickness up to ~1 mm. 15. SUBJECT TERMS large planar equi-biaxial strain, membrane, dielectric elastomers, electromechanical

Long-term erosion rates of Panamanian drainage basins determined using in situ 10Be

NASA Astrophysics Data System (ADS)

Gonzalez, Veronica Sosa; Bierman, Paul R.; Nichols, Kyle K.; Rood, Dylan H.

2016-12-01

Erosion rates of tropical landscapes are poorly known. Using measurements of in situ-produced 10Be in quartz extracted from river and landslide sediment samples, we calculate long-term erosion rates for many physiographic regions of Panama. We collected river sediment samples from a wide variety of watersheds (n = 35), and then quantified 24 landscape-scale variables (physiographic, climatic, seismic, geologic, and land-use proxies) for each watershed before determining the relationship between these variables and long-term erosion rates using linear regression, multiple regression, and analysis of variance (ANOVA). We also used grain-size-specific 10Be analysis to infer the effect of landslides on the concentration of 10Be in fluvial sediment and thus on erosion rates. Cosmogenic 10Be-inferred, background erosion rates in Panama range from 26 to 595 m My- 1, with an arithmetic average of 201 m My- 1, and an area-weighted average of 144 m My- 1. The strongest and most significant relationship in the dataset was between erosion rate and silicate weathering rate, the mass of material leaving the basin in solution. None of the topographic variables showed a significant relationship with erosion rate at the 95% significance level; we observed weak but significant correlation between erosion rates and several climatic variables related to precipitation and temperature. On average, erosion rates in Panama are higher than other cosmogenically-derived erosion rates in tropical climates including those from Puerto Rico, Madagascar, Australia and Sri Lanka, likely the result of Panama's active tectonic setting and thus high rates of seismicity and uplift. Contemporary sediment yield and cosmogenically-derived erosion rates for three of the rivers we studied are similar, suggesting that human activities are not increasing sediment yield above long-term erosion rate averages in Panama. 10Be concentration is inversely proportional to grain size in landslide and fluvial samples from Panama; finer grain sizes from landslide material have lower 10Be concentration than fine-grained fluvial sediment. Large grains from both landslide and stream sediments have similarly low 10Be concentrations. These data suggest that fluvial gravel is delivered to the channel by landslides whereas sand is preferentially delivered by soil creep and bank collapse. Furthermore, the difference in 10Be concentration in sand-sized material delivered by soil creep and that delivered by landsliding suggests that the frequency and intensity of landslides influence basin scale erosion rates.

[Risk factors in the living environment of early spontaneous abortion pregnant women].

PubMed

Liu, Xin-yan; Bian, Xu-ming; Han, Jing-xiu; Cao, Zhao-jin; Fan, Guang-sheng; Zhang, Chao; Zhang, Wen-li; Zhang, Shu-zhen; Sun, Xiao-guang

2007-10-01

To study the relationship between early spontaneous abortion and living environment, and explore the risk factors of spontaneous abortion. We conducted analysis based on the interview of 200 spontaneous abortion cases and the matched control (age +/- 2 years) by using multifactor Logistic regression analysis. The proportions of watching TV > or =10 hours/week, operating computer > or =45 hours/week, using copycat, microwave oven and mobile phone, electromagnetism equipment near the dwell or work place, e. g. switch room < or =50 m and launching tower < or =500 m in the cases are significantly higher than those in the controls in single factor analysis (all P < 0.05). After adjusted the effect of other risk factors by multifactor analysis, using microwave oven and mobile phone, contacting abnormal smell of fitment material > or =3 months, having emotional stress during the first term of pregnancy and spontaneous abortion history were significantly associated with risk of spontaneous abortion. The odds ratios of these risk factors were 2.23 and 4.63, respectively. Using microwave oven and mobile phone, contacting abnormal smell of fitment material > or =3 months, having emotional stress during the first term of pregnancy, and spontaneous abortion history are risk factors of early spontaneous abortion.

An overview of the Evaluation of Oxygen Interaction with Materials-third phase (EOIM-3) experiment: Space Shuttle Mission 46

NASA Technical Reports Server (NTRS)

Leger, Lubert J.; Koontz, Steven L.; Visentine, James T.; Hunton, Donald

1993-01-01

The interaction of the atomic oxygen (AO) component of the low earth orbit (LEO) environment with spacecraft materials has been the subject of several flight experiments over the past 11 years. The effect of AO interactions with materials has been shown to be significant for long-lived spacecraft such as Space Station Freedom and has resulted in materials changes for externally exposed surfaces. The data obtained from previous flight experiments, augmented by limited ground-based evaluation, have been used to evaluate hardware performance and select materials. Questions pertaining to the accuracy of this data base remain, resulting from the use of long-term ambient density models to estimate the O-atom fluxes and fluences needed to calculate materials reactivity in short-term flight experiments. The EOIM-3 flight experiment was designed to produce benchmark AO reactivity data and was carried out during STS-46. Ambient density measurements were made with a quadrupole mass spectrometer which was calibrated for AO measurements in a unique ground-based test facility. The combination of these data with the predictions of ambient density models allows an assessment of the accuracy of measured reaction rates on a wide variety of materials, many of which had never been tested in LEO before. The mass spectrometer is also used to obtain a better definition of the local neutral and plasma environments resulting from interaction of the ambient atmosphere with various spacecraft surfaces. In addition, the EOIM-3 experiment was designed to produce information on the effects of temperature, mechanical stress, and solar exposure on the AO reactivity of a wide range of materials. An overview of the EOIM-3 methods and results are presented.

49 CFR 173.59 - Description of terms for explosives.

Code of Federal Regulations, 2012 CFR

2012-10-01

... perforating guns, charged, oil well, without detonator. Articles consisting of a steel tube or metallic strip... MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS SHIPPERS... fiber, metal or other material containing only propellant explosive. The term excludes charges, shaped...

Fusion Materials Research at Oak Ridge National Laboratory in Fiscal Year 2015

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

Wiffen, F. W.; Katoh, Yutai; Melton, Stephanie G.

The realization of fusion energy is a formidable challenge with significant achievements resulting from close integration of the plasma physics and applied technology disciplines. Presently, the most significant technological challenge for the near-term experiments such as ITER, and next generation fusion power systems, is the inability of current materials and components to withstand the harsh fusion nuclear environment. The overarching goal of the Oak Ridge National Laboratory (ORNL) fusion materials program is to provide the applied materials science support and understanding to underpin the ongoing Department of Energy (DOE) Office of Science fusion energy program while developing materials for fusionmore » power systems. In doing so the program continues to be integrated both with the larger United States (US) and international fusion materials communities, and with the international fusion design and technology communities.This document provides a summary of Fiscal Year (FY) 2015 activities supporting the Office of Science, Office of Fusion Energy Sciences Materials Research for Magnetic Fusion Energy (AT-60-20-10-0) carried out by ORNL. The organization of this report is mainly by material type, with sections on specific technical activities. Four projects selected in the Funding Opportunity Announcement (FOA) solicitation of late 2011 and funded in FY2012-FY2014 are identified by “FOA” in the titles. This report includes the final funded work of these projects, although ORNL plans to continue some of this work within the base program.« less

High Temperature Steam Electrolysis: Demonstration of Improved Long-Term Performance

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

J. E. O'Brien; X. Zhang; R. C. O'Brien

2011-11-01

Long-term performance is an ongoing issue for hydrogen production based on high-temperature steam electrolysis (HTSE). For commercial deployment, solid-oxide electrolysis stacks must achieve high performance with long-term degradation rates of {approx}0.5%/1000 hours or lower. Significant progress has been achieved toward this goal over the past few years. This paper will provide details of progress achieved under the Idaho National Laboratory high temperature electrolysis research program. Recent long-term stack tests have achieved high initial performance with degradation rates less than 5%/khr. These tests utilize internally manifolded stacks with electrode-supported cells. The cell material sets are optimized for the electrolysis mode ofmore » operation. Details of the cells and stacks will be provided along with details of the test apparatus, procedures, and results.« less

Long-term outcome of social skills intervention based on interactive LEGO play.

PubMed

Legoff, Daniel B; Sherman, Michael

2006-07-01

LEGO building materials have been adapted as a therapeutic modality for increasing motivation to participate in social skills intervention, and providing a medium through which children with social and communication handicaps can effectively interact. A 3 year retrospective study of long-term outcome for autistic spectrum children participating in LEGO therapy (N = 60) compared Vineland Adaptive Behavior Scale socialization domain (VABS-SD) and Gilliam Autism Rating Scale social interaction subscale (GARS-SI) scores preand post-treatment with a matched comparison sample (N = 57) who received comparable non-LEGO therapy. Although both groups made significant gains on the two outcome measures, LEGO participants improved significantly more than the comparison subjects. Diagnosis and pre-treatment full-scale IQ scores did not predict outcome scores; however, Vineland adaptive behavior composite, Vineland communication domain, and verbal IQ all predicted outcome on the VABS-SD, especially for the LEGO therapy group. Results are discussed in terms of implications for methods of social skills intervention for autistic spectrum disorders.

Factors affecting the perception of whole-body vibration of occupational drivers: an analysis of posture and manual materials handling and musculoskeletal disorders

PubMed Central

Raffler, Nastaran; Ellegast, Rolf; Kraus, Thomas; Ochsmann, Elke

2016-01-01

Due to the high cost of conducting field measurements, questionnaires are usually preferred for the assessment of physical workloads and musculoskeletal disorders (MSDs). This study compares the physical workloads of whole-body vibration (WBV) and awkward postures by direct field measurements and self-reported data of 45 occupational drivers. Manual materials handling (MMH) and MSDs were also investigated to analyse their effect on drivers' perception. Although the measured values for WBV exposure were very similarly distributed among the drivers, the subjects' perception differed significantly. Concerning posture, subjects seemed to estimate much better when the difference in exposure was significantly large. The percentage of measured awkward trunk and head inclination were significantly higher for WBV-overestimating subjects than non-overestimators; 77 and 80% vs. 36 and 33%. Health complaints in terms of thoracic spine, cervical spine and shoulder–arm were also significantly more reported by WBV-overestimating subjects (42, 67, 50% vs. 0, 25, 13%, respectively). Although more MMH was reported by WBV-overestimating subjects, there was no statistical significance in this study. PMID:26114619

Influence of implant location on the clinical outcomes of implant abutments: a systematic review and meta-analysis

PubMed Central

ElHoussiney, Amr G; Zhang, He; Song, Jinlin; Ji, Ping; Wang, Lu; Yang, Sheng

2018-01-01

Purpose To compare the failure events and incidence of complications of different abutment materials in anterior and posterior regions. Failure was defined as complete loss of the abutment requiring replacement by a new abutment. Materials and methods Electronic searches using PubMed/Medline and Google Scholar complemented with manual searches were performed with specific search terms. Searches were restricted to publications in English between January 2006 and March 2016. Results A total of 863 and 1,264 implants were inserted in the anterior and posterior regions, respectively, in a total of 1,529 patients. No titanium abutments failed in anterior or posterior regions. On the other hand, 1.6% of zirconia abutments failed in the anterior region and 1.5% failed in the posterior region. Technical complications occurred mostly in the posterior region and mostly involved zirconia abutment. Meta-analysis was possible only for zirconia-abutment failure, due to considerable heterogeneity of studies and outcome variables. No significant difference in failure rate was found between anterior and posterior zirconia abutments (risk ratio 1.53, 95% CI 0.49–4.77; P=0.47). Conclusion This systematic review and meta-analysis showed similar outcomes of different abutment materials when used in anterior and posterior regions in terms of failure events and biological and aesthetic complications. The only significant finding was the increased incidence of technical complications in the posterior region, mostly involving zirconia abutments. Abutment-screw loosening was the most common technical complication. PMID:29520162

Micro-engineered first wall tungsten armor for high average power laser fusion energy systems

NASA Astrophysics Data System (ADS)

Sharafat, Shahram; Ghoniem, Nasr M.; Anderson, Michael; Williams, Brian; Blanchard, Jake; Snead, Lance; HAPL Team

2005-12-01

The high average power laser program is developing an inertial fusion energy demonstration power reactor with a solid first wall chamber. The first wall (FW) will be subject to high energy density radiation and high doses of high energy helium implantation. Tungsten has been identified as the candidate material for a FW armor. The fundamental concern is long term thermo-mechanical survivability of the armor against the effects of high temperature pulsed operation and exfoliation due to the retention of implanted helium. Even if a solid tungsten armor coating would survive the high temperature cyclic operation with minimal failure, the high helium implantation and retention would result in unacceptable material loss rates. Micro-engineered materials, such as castellated structures, plasma sprayed nano-porous coatings and refractory foams are suggested as a first wall armor material to address these fundamental concerns. A micro-engineered FW armor would have to be designed with specific geometric features that tolerate high cyclic heating loads and recycle most of the implanted helium without any significant failure. Micro-engineered materials are briefly reviewed. In particular, plasma-sprayed nano-porous tungsten and tungsten foams are assessed for their potential to accommodate inertial fusion specific loads. Tests show that nano-porous plasma spray coatings can be manufactured with high permeability to helium gas, while retaining relatively high thermal conductivities. Tungsten foams where shown to be able to overcome thermo-mechanical loads by cell rotation and deformation. Helium implantation tests have shown, that pulsed implantation and heating releases significant levels of implanted helium. Helium implantation and release from tungsten was modeled using an expanded kinetic rate theory, to include the effects of pulsed implantations and thermal cycles. Although, significant challenges remain micro-engineered materials are shown to constitute potential candidate FW armor materials.

Evaluation of a novel multiple phase veneering ceramic.

PubMed

Sinthuprasirt, Pannapa; van Noort, Richard; Moorehead, Robert; Pollington, Sarah

2015-04-01

To produce a new veneering ceramic based on the production of a multiple phase glass-ceramic with improved performance in terms of strength and toughness. A composition of 60% leucite, 20% diopside and 20% feldspathic glass was prepared, blended and a heat treatment schedule of 930°C for 5 min was derived from differential thermal analysis (DTA) of the glasses. X-ray diffraction (XRD) and SEM analysis determined the crystalline phases and microstructure. Chemical solubility, biaxial flexural strength (BFS), fracture toughness, hardness, total transmittance and coefficient of thermal expansion (CTE) were all measured in comparison to a commercial veneering ceramic (VITA VM9). Thermal shock resistance of the leucite-diopside and VITA VM9 veneered onto a commercial high strength zirconia (Vita In-Ceram YZ) was also assessed. Statistical analysis was undertaken using Independent Samples t-test. Weibull analysis was employed to examine the reliability of the strength data. The mean chemical solubility was 6 μg/cm(2) for both ceramics (P=1.00). The mean BFS was 109 ± 8 MPa for leucite-diopside ceramic and 79 ± 11 MPa for VITA VM9 ceramic (P=0.01). Similarly, the leucite-diopside ceramic demonstrated a significantly higher fracture toughness and hardness. The average total transmittance was 46.3% for leucite-diopside ceramic and 39.8% for VITA VM9 (P=0.01). The leucite-diopside outperformed the VITA VM9 in terms of thermal shock resistance. Significance This novel veneering ceramic exhibits significant improvements in terms of mechanical properties, yet retains a high translucency and is the most appropriate choice as a veneering ceramic for a zirconia base core material. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

MATERIALS FOR MODERNIZATION.

ERIC Educational Resources Information Center

JACKSON, R. GRAHAM

CHOICES AND ISSUES IN SELECTING MATERIALS FOR MODERNIZATION OF SCHOOL BUILDINGS ARE DISCUSSED IN THIS REPORT. BACKGROUND INFORMATION IS INTRODUCED IN TERMS OF REASONS FOR ABANDONMENT, THE CAUSES AND EFFECTS OF SCHOOL BUILDING OBSOLESCENCE, AND PROBLEMS IN THE MODERNIZATION PROCESS. INTERIOR PARTITIONS ARE DISCUSSED IN TERMS OF BUILDING MATERIALS,…

Photothermal characterization of encapsulant materials for photovoltaic modules

NASA Technical Reports Server (NTRS)

Liang, R. H.; Gupta, A.; Distefano, S.

1982-01-01

A photothermal test matrix and a low cost testing apparatus for encapsulant materials of photovoltaic modules were defined. Photothermal studies were conducted to screen and rank existing as well as future encapsulant candidate materials and/or material formulations in terms of their long term physiochemical stability under accelerated photothermal aging conditions. Photothermal characterization of six candidate pottant materials and six candidate outer cover materials were carried out. Principal products of photothermal degradation are identified. Certain critical properties are also monitored as a function of photothermal aging.

Comparison of Early-period Results of Nasal Splint and Merocel Nasal Packs in Septoplasty

PubMed Central

Bingöl, Fatih; Budak, Ali; Şimşek, Eda; Kılıç, Korhan; Bingöl, Buket Özel

2017-01-01

Objective Several types of nasal packs are used postoperatively in septoplasty. In this study, we compared two commonly used nasal packing materials, the intranasal septal splint with airway and Merocel tampon, in terms of pain, bleeding, nasal obstruction, eating difficulties, discomfort in sleep, and pain and bleeding during removal of packing in the early period. Methods The study group included 60 patients undergoing septoplasty. Patients were divided into two groups (n=30 in each group). An intranasal splint with airway was used for the patients in the first group after septoplasty, while Merocel nasal packing was used for the second group. Patients were investigated in terms of seven different factors - pain, bleeding while the tampon was in place, nasal obstruction, eating difficulties, night sleep, pain during removal of the nasal packing, and bleeding after removal of packing. Results There was no statistically significant difference between the groups in terms of pain 24 hours after operation (p=0.05), while visual analog scale (VAS) scores for nasal obstruction, night sleep, eating difficulties, and pain during packing removal were lower in the nasal splint group with a statistically significant difference (p<0.05). There was no statistically significant difference between the groups in terms of postoperative bleeding (p=0.23). Significantly less bleeding occurred during removal of the packing in the nasal splint group (p<0.05). Conclusion Our study indicates that the nasal splint was more comfortable and effective in terms of causing lesser bleeding and pain during removal of packing. PMID:29392071

Effects of long-term repeated topical fluoride applications and adhesion promoter on shear bond strengths of orthodontic brackets

PubMed Central

Endo, Toshiya; Ishida, Rieko; Komatsuzaki, Akira; Sanpei, Shinya; Tanaka, Satoshi; Sekimoto, Tsuneo

2014-01-01

Objective: The purpose of this study was to assess the effects of long-term repeated topical application of fluoride before bonding and an adhesion promoter on the bond strength of orthodontic brackets. Materials and Methods: A total of 76 bovine incisors were collected and divided equally into four groups. In group 1, the brackets were bonded without topical fluoride application or adhesion promoter. In group 2, before bonding, the adhesion promoter was applied to nonfluoridated enamel. In group 3, the brackets were bonded without the application of the adhesion promoter to enamel, which had undergone long-term repeated topical fluoride treatments. Teeth in group 4 received the long-term repeated topical applications of fluoride, and the brackets were bonded using the adhesion promoter. All the brackets were bonded using BeautyOrtho Bond self-etching adhesive. The shear bond strength was measured and the bond failure modes were evaluated with the use of the adhesive remnant index (ARI) after debonding. Results: The mean shear bond strength was significantly lower in group 3 than in groups 1, 2, and 4, and there were no significant differences between the groups except for group 3. There were significant differences in the distribution of ARI scores between groups 2 and 3, and between groups 3 and 4. Conclusions: The adhesion promoter can recover the bond strength reduced by the long-term repeated topical applications of fluoride to the prefluoridation level and had a significantly great amount of adhesives left on either fluoridated or nonfluoridated enamel. PMID:25512720

50 CFR 520.3 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... and Fisheries MARINE MAMMAL COMMISSION PUBLIC AVAILABILITY OF AGENCY MATERIALS § 520.3 Definitions. As used in these regulations: (a) The term Commission means the Marine Mammal Commission; (b) The term Director means the Executive Director of the Marine Mammal Commission; (c) The term exempt materials means...

Internet search term affects the quality and accuracy of online information about developmental hip dysplasia.

PubMed

Fabricant, Peter D; Dy, Christopher J; Patel, Ronak M; Blanco, John S; Doyle, Shevaun M

2013-06-01

The recent emphasis on shared decision-making has increased the role of the Internet as a readily accessible medical reference source for patients and families. However, the lack of professional review creates concern over the quality, accuracy, and readability of medical information available to patients on the Internet. Three Internet search engines (Google, Yahoo, and Bing) were evaluated prospectively using 3 difference search terms of varying sophistication ("congenital hip dislocation," "developmental dysplasia of the hip," and "hip dysplasia in children"). Sixty-three unique Web sites were evaluated by each of 3 surgeons (2 fellowship-trained pediatric orthopaedic attendings and 1 orthopaedic chief resident) for quality and accuracy using a set of scoring criteria based on the AAOS/POSNA patient education Web site. The readability (literacy grade level) of each Web site was assessed using the Fleisch-Kincaid score. There were significant differences noted in quality, accuracy, and readability of information depending on the search term used. The search term "developmental dysplasia of the hip" provided higher quality and accuracy compared with the search term "congenital hip dislocation." Of the 63 total Web sites, 1 (1.6%) was below the sixth grade reading level recommended by the NIH for health education materials and 8 (12.7%) Web sites were below the average American reading level (eighth grade). The quality and accuracy of information available on the Internet regarding developmental hip dysplasia significantly varied with the search term used. Patients seeking information about DDH on the Internet may not understand the materials found because nearly all of the Web sites are written at a level above that recommended for publically distributed health information. Physicians should advise their patients to search for information using the term "developmental dysplasia of the hip" or, better yet, should refer patients to Web sites that they have personally reviewed for content and clarity. Orthopaedic surgeons, professional societies, and search engines should undertake efforts to ensure that patients have access to information about DDH that is both accurate and easily understandable.

Modeling Strain Rate Effect of Heterogeneous Materials Using SPH Method

NASA Astrophysics Data System (ADS)

Ma, G. W.; Wang, X. J.; Li, Q. M.

2010-11-01

The strain rate effect on the dynamic compressive failure of heterogeneous material based on the smoothed particle hydrodynamics (SPH) method is studied. The SPH method employs a rate-insensitive elasto-plastic damage model incorporated with a Weibull distribution law to reflect the mechanical behavior of heterogeneous rock-like materials. A series of simulations are performed for heterogeneous specimens by applying axial velocity conditions, which induce different strain-rate loadings to the specimen. A detailed failure process of the specimens in terms of microscopic crack-activities and the macro-mechanical response are discussed. Failure mechanisms between the low and high strain rate cases are compared. The result shows that the strain-rate effects on the rock strength are mainly caused by the changing internal pressure due to the inertial effects as well as the material heterogeneity. It also demonstrates that the inertial effect becomes significant only when the induced strain rate exceeds a threshold, below which, the dynamic strength enhancement can be explained due to the heterogeneities in the material. It also shows that the dynamic strength is affected more significantly for a relatively more heterogeneous specimen, which coincides with the experimental results showing that the poor quality specimen had a relatively larger increase in the dynamic strength.

Investigation of the foundations of a Byzantine church by three-dimensional seismic tomography

NASA Astrophysics Data System (ADS)

Polymenakos, L.; Papamarinopoulos, S.; Miltiadou, A.; Charkiolakis, N.

2005-02-01

Byzantine public buildings are of high historical and cultural value. Churches, in particular, are of high architectural and artistic value because they are built using various materials and construction techniques and may contain significant frescoes and mosaics. The knowledge of the state of foundations and ground material conditions is important for their proper restoration and preservation. Seismic tomography is employed to investigate the foundation structure and ground material of a Byzantine church. Energy sources are placed across the floor of the church and surrounding courts, while recorders are placed in a subterranean crypt. Travel time data are analyzed and processed with a three-dimensional (3D) tomographic inversion software in order to construct seismic velocity images at the foundation and below foundation level. Velocity variations are known to correlate well with the lithological character of the earth materials, thus providing important structural and lithological information. A case study from a Byzantine church of 11th c. A.D. in the suburbs of Athens, Greece, is presented. The objective of this research is the nondestructive investigation of unknown underground structures or void spaces, mainly under the floor of the building. The results are interpreted in terms of the foundation elements as well as of significant variations in the earth material character.

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

ZERODUR®: new stress corrosion data improve strength fatigue prediction

NASA Astrophysics Data System (ADS)

Hartmann, Peter; Kleer, Günter; Rist, Tobias

2015-09-01

The extremely low thermal expansion glass ceramic ZERODUR® finds more and more applications as sophisticated light weight structures with thin ribs or as thin shells. Quite often they will be subject to higher mechanical loads such as rocket launches or modulating wobbling vibrations. Designing such structures requires calculation methods and data taking into account their long term fatigue. With brittle materials fatigue is not only given by the material itself but to a high extent also by its surface condition and the environmental media especially humidity. This work extends the latest data and information gathered on the bending strength of ZERODUR® with new results concerning its long term behavior under tensile stress. The parameter needed for prediction calculations which combines the influences of time and environmental media is the stress corrosion constant n. Results of the past differ significantly from each other. In order to obtain consistent data the stress corrosion constant has been measured with the method comparing the breakage statistical distributions at different stress increase rates. For better significance the stress increase rate was varied over four orders of magnitude from 0.004 MPa/s to 40 MPa/s. Experiments were performed under normal humidity for long term earth bound applications and under nitrogen atmosphere as equivalent to dry environment occurring for example with telescopes in deserts and also equivalent to vacuum for space applications. As shown earlier the bending strength of diamond ground surfaces of ZERODUR® can be represented with a three parameter Weibull distribution. Predictions on the long term strength change of ZERODUR® structures under tensile stress are possible with reduced uncertainty if Weibull threshold strength values are considered and more reliable stress corrosion constant data are applied.

Computational electrodynamics in material media with constraint-preservation, multidimensional Riemann solvers and sub-cell resolution - Part II, higher order FVTD schemes

NASA Astrophysics Data System (ADS)

Balsara, Dinshaw S.; Garain, Sudip; Taflove, Allen; Montecinos, Gino

2018-02-01

The Finite Difference Time Domain (FDTD) scheme has served the computational electrodynamics community very well and part of its success stems from its ability to satisfy the constraints in Maxwell's equations. Even so, in the previous paper of this series we were able to present a second order accurate Godunov scheme for computational electrodynamics (CED) which satisfied all the same constraints and simultaneously retained all the traditional advantages of Godunov schemes. In this paper we extend the Finite Volume Time Domain (FVTD) schemes for CED in material media to better than second order of accuracy. From the FDTD method, we retain a somewhat modified staggering strategy of primal variables which enables a very beneficial constraint-preservation for the electric displacement and magnetic induction vector fields. This is accomplished with constraint-preserving reconstruction methods which are extended in this paper to third and fourth orders of accuracy. The idea of one-dimensional upwinding from Godunov schemes has to be significantly modified to use the multidimensionally upwinded Riemann solvers developed by the first author. In this paper, we show how they can be used within the context of a higher order scheme for CED. We also report on advances in timestepping. We show how Runge-Kutta IMEX schemes can be adapted to CED even in the presence of stiff source terms brought on by large conductivities as well as strong spatial variations in permittivity and permeability. We also formulate very efficient ADER timestepping strategies to endow our method with sub-cell resolving capabilities. As a result, our method can be stiffly-stable and resolve significant sub-cell variation in the material properties within a zone. Moreover, we present ADER schemes that are applicable to all hyperbolic PDEs with stiff source terms and at all orders of accuracy. Our new ADER formulation offers a treatment of stiff source terms that is much more efficient than previous ADER schemes. The computer algebra system scripts for generating ADER time update schemes for any general PDE with stiff source terms are also given in the electronic supplements to this paper. Second, third and fourth order accurate schemes for numerically solving Maxwell's equations in material media are presented in this paper. Several stringent tests are also presented to show that the method works and meets its design goals even when material permittivity and permeability vary by an order of magnitude over just a few zones. Furthermore, since the method is unconditionally stable and sub-cell-resolving in the presence of stiff source terms (i.e. for problems involving giant variations in conductivity over just a few zones), it can accurately handle such problems without any reduction in timestep. We also show that increasing the order of accuracy offers distinct advantages for resolving sub-cell variations in material properties. Most importantly, we show that when the accuracy requirements are stringent the higher order schemes offer the shortest time to solution. This makes a compelling case for the use of higher order, sub-cell resolving schemes in CED.

Construction materials, monuments and environment

NASA Astrophysics Data System (ADS)

Prikryl, R.; Siegesmund, S.; Török, A.; Brimblecombe, P.; Gomez-Heras, M.

2012-04-01

Construction materials (natural stone, aggregates, bricks, cement, lime, mortar, etc.) form a wide and heterogeneous group both from the genetic and technological point of view. These materials deserve attention from the scientific community due to their long-term use, importance for society and sensitivity to the environment. Most geomaterials have also been used in important monuments designated as a part of the World Cultural Heritage and/or make part of national monuments. Despite of the wide-ranges of studies and our rapidly increasing understanding of material behaviour, our knowledge is still rather limited in many aspects. This concerns the characterisation of traditional raw materials, the knowledge of their processing and use, and/or durability and compatibility assessment. The exploitation and sustainable use of these materials are also new and emerging challenges in the modern society. The use of local materials for monuments can be considered as a part of our cultural and technological heritage, which has, however, significantly deteriorated during the past several decades. This paper summarizes the general topics related to a modern analysis of traditional construction materials derived from the Earth, and on the characteristic aspects of the behaviour of these materials on selected monuments.

Biological Fuel Cells and Membranes.

PubMed

Ghassemi, Zahra; Slaughter, Gymama

2017-01-17

Biofuel cells have been widely used to generate bioelectricity. Early biofuel cells employ a semi-permeable membrane to separate the anodic and cathodic compartments. The impact of different membrane materials and compositions has also been explored. Some membrane materials are employed strictly as membrane separators, while some have gained significant attention in the immobilization of enzymes or microorganisms within or behind the membrane at the electrode surface. The membrane material affects the transfer rate of the chemical species (e.g., fuel, oxygen molecules, and products) involved in the chemical reaction, which in turn has an impact on the performance of the biofuel cell. For enzymatic biofuel cells, Nafion, modified Nafion, and chitosan membranes have been used widely and continue to hold great promise in the long-term stability of enzymes and microorganisms encapsulated within them. This article provides a review of the most widely used membrane materials in the development of enzymatic and microbial biofuel cells.

Ionic liquid-based materials: a platform to design engineered CO2 separation membranes.

PubMed

Tomé, Liliana C; Marrucho, Isabel M

2016-05-21

During the past decade, significant advances in ionic liquid-based materials for the development of CO2 separation membranes have been accomplished. This review presents a perspective on different strategies that use ionic liquid-based materials as a unique tuneable platform to design task-specific advanced materials for CO2 separation membranes. Based on compilation and analysis of the data hitherto reported, we provide a judicious assessment of the CO2 separation efficiency of different membranes, and highlight breakthroughs and key challenges in this field. In particular, configurations such as supported ionic liquid membranes, polymer/ionic liquid composite membranes, gelled ionic liquid membranes and poly(ionic liquid)-based membranes are detailed, discussed and evaluated in terms of their efficiency, which is attributed to their chemical and structural features. Finally, an integrated perspective on technology, economy and sustainability is provided.

Performance and cost of materials for lithium-based rechargeable automotive batteries

NASA Astrophysics Data System (ADS)

Schmuch, Richard; Wagner, Ralf; Hörpel, Gerhard; Placke, Tobias; Winter, Martin

2018-04-01

It is widely accepted that for electric vehicles to be accepted by consumers and to achieve wide market penetration, ranges of at least 500 km at an affordable cost are required. Therefore, significant improvements to lithium-ion batteries (LIBs) in terms of energy density and cost along the battery value chain are required, while other key performance indicators, such as lifetime, safety, fast-charging ability and low-temperature performance, need to be enhanced or at least sustained. Here, we review advances and challenges in LIB materials for automotive applications, in particular with respect to cost and performance parameters. The production processes of anode and cathode materials are discussed, focusing on material abundance and cost. Advantages and challenges of different types of electrolyte for automotive batteries are examined. Finally, energy densities and costs of promising battery chemistries are critically evaluated along with an assessment of the potential to fulfil the ambitious targets of electric vehicle propulsion.

Biological Fuel Cells and Membranes

PubMed Central

Ghassemi, Zahra; Slaughter, Gymama

2017-01-01

Biofuel cells have been widely used to generate bioelectricity. Early biofuel cells employ a semi-permeable membrane to separate the anodic and cathodic compartments. The impact of different membrane materials and compositions has also been explored. Some membrane materials are employed strictly as membrane separators, while some have gained significant attention in the immobilization of enzymes or microorganisms within or behind the membrane at the electrode surface. The membrane material affects the transfer rate of the chemical species (e.g., fuel, oxygen molecules, and products) involved in the chemical reaction, which in turn has an impact on the performance of the biofuel cell. For enzymatic biofuel cells, Nafion, modified Nafion, and chitosan membranes have been used widely and continue to hold great promise in the long-term stability of enzymes and microorganisms encapsulated within them. This article provides a review of the most widely used membrane materials in the development of enzymatic and microbial biofuel cells. PMID:28106711

Redox‐Flow Batteries: From Metals to Organic Redox‐Active Materials

PubMed Central

Winsberg, Jan; Hagemann, Tino; Janoschka, Tobias; Hager, Martin D.

2016-01-01

Abstract Research on redox‐flow batteries (RFBs) is currently experiencing a significant upturn, stimulated by the growing need to store increasing quantities of sustainably generated electrical energy. RFBs are promising candidates for the creation of smart grids, particularly when combined with photovoltaics and wind farms. To achieve the goal of “green”, safe, and cost‐efficient energy storage, research has shifted from metal‐based materials to organic active materials in recent years. This Review presents an overview of various flow‐battery systems. Relevant studies concerning their history are discussed as well as their development over the last few years from the classical inorganic, to organic/inorganic, to RFBs with organic redox‐active cathode and anode materials. Available technologies are analyzed in terms of their technical, economic, and environmental aspects; the advantages and limitations of these systems are also discussed. Further technological challenges and prospective research possibilities are highlighted. PMID:28070964

Iridium-coated rhenium thrusters by CVD

NASA Technical Reports Server (NTRS)

Harding, J. T.; Kazaroff, J. M.; Appel, M. A.

1989-01-01

Operation of spacecraft thrusters at increased temperature reduces propellant requirements. Inasmuch as propellant comprises the bulk of a satellite's mass, even a small percentage reduction makes possible a significant enhancement of the mission in terms of increased payload. Because of its excellent high temperature strength, rhenium is often the structural material of choice. It can be fabricated into free-standing shapes by chemical vapor deposition (CVD) onto an expendable mandrel. What rhenium lacks is oxidation resistance, but this can be provided by a coating of iridium, also by CVD. This paper describes the process used by Ultramet to fabricate 22-N (5-lbf) and, more recently, 445-N (100-lbf) Ir/Re thrusters; characterizes the CVD-deposited materials; and summarizes the materials effects of firing these thrusters. Optimal propellant mixture ratios can be employed because the materials withstand an oxidizing environment up to the melting temperature of iridium, 2400 C (4350 F).

Iridium-coated rhenium thrusters by CVD

NASA Technical Reports Server (NTRS)

Harding, John T.; Kazaroff, John M.; Appel, Marshall A.

1988-01-01

Operation of spacecraft thrusters at increased temperature reduces propellant requirements. Inasmuch as propellant comprises the bulk of a satellite's mass, even a small percentage reduction makes possible a significant enhancement of the mission in terms of increased payload. Because of its excellent high temperature strength, rhenium is often the structural material of choice. It can be fabricated into free-standing shapes by chemical vapor deposition (CVD) onto an expendable mandrel. What rhenium lacks is oxidation resistance, but this can be provided by a coating of iridium, also by CVD. This paper describes the process used by Ultramet to fabricate 22-N (5-lbf) and, more recently, 445-N (100-lbf) Ir/Re thrusters; characterizes the CVD-deposited materials; and summarizes the materials effects of firing these thrusters. Optimal propellant mixture ratios can be employed because the materials withstand an oxidizing environment up to the meltimg temperature of iridium, 2400 C (4350 F).

In vitro caries-inhibitory properties of a silver cermet.

PubMed

Swift, E J

1989-06-01

Recurrent caries is one of the primary causes of failure of dental restorations. One method for reducing the frequency and severity of this problem is the use of fluoride-releasing restorative materials. The glass-ionomer cements are a type of fluoride-releasing material. They have been used extensively in recent years for a variety of clinical applications. However, in comparison with other restorative materials such as amalgam and composite resins, glass ionomers have relatively poor physical properties. Sintering of silver particles to glass-ionomer powder is a means of improving these physical properties. The sintered material is called a silver-glass ionomer or silver cermet. This study examined the in vitro caries-inhibitory potential of a silver cement by means of two methods. First, long-term fluoride release was measured. Second, an artificial caries system was used for evaluation of caries inhibition by cerment restorations in extracted teeth. In comparison with a standard glass-ionomer restorative material, fluoride release from the cermet material was significantly less throughout a 12-month period. The results from the artificial caries system indicated that this decreased fluoride release corresponded with a lesser degree of caries inhibition. Lesions around cermet restorations in both enamel and root surfaces were significantly more severe than those around conventional glass-ionomer restorations. However, in comparison with amalgam and composite resin restorations, the cermet did have some cariostatic activity.

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

Howell, C; Vu, TL; Lin, JJ

Inspired by the long-term effectiveness of living antifouling materials, we have developed a method for the self-replenishment of synthetic biofouling-release surfaces. These surfaces are created by either molding or directly embedding 3D vascular systems into polydimethylsiloxane (PDMS) and filling them with a silicone oil to generate a nontoxic oil-infused material. When replenished with silicone oil from an outside source, these materials are capable of self-lubrication and continuous renewal of the interfacial fouling-release layer. Under accelerated lubricant loss conditions, fully infused vascularized samples retained significantly more lubricant than equivalent nonvascularized controls. Tests of lubricant-infused PDMS in static cultures of the infectiousmore » bacteria Staphylococcus aureus and Escherichia coli as well as the green microalgae Botryococcus braunii, Chlamydomonas reinhardtii, Dunaliella sauna, and Nannochloropsis oculata showed a significant reduction in biofilm adhesion compared to PDMS and glass controls containing no lubricant. Further experiments on vascularized versus nonvascularized samples that had been subjected to accelerated lubricant evaporation conditions for up to 48 h showed significantly less biofilm adherence on the vascularized surfaces. These results demonstrate the ability of an embedded lubricant-filled vascular network to improve the longevity of fouling-release surfaces.« less

Self-Replenishing Vascularized Fouling-Release Surfaces

DOE PAGES

Howell, Caitlin; Vu, Thy L.; Lin, Jennifer J.; ...

2014-08-13

Inspired by the long-term effectiveness of living antifouling materials, we have developed a method for the selfreplenishment of synthetic biofouling-release surfaces. These surfaces are created by either molding or directly embedding 3D vascular systems into polydimethylsiloxane (PDMS) and filling them with a silicone oil to generate a nontoxic oil-infused material. When replenished with silicone oil from an outside source, these materials are capable of self-lubrication and continuous renewal of the interfacial fouling-release layer. Under accelerated lubricant loss conditions, fully infused vascularized samples retained significantly more lubricant than equivalent nonvascularized controls. Tests of lubricant-infused PDMS in static cultures of the infectiousmore » bacteria Staphylococcus aureus and Escherichia coli as well as the green microalgae Botryococcus braunii, Chlamydomonas reinhardtii, Dunaliella salina, and Nannochloropsis oculata showed a significant reduction in biofilm adhesion compared to PDMS and glass controls containing no lubricant. Further experiments on vascularized versus nonvascularized samples that had been subjected to accelerated lubricant evaporation conditions for up to 48 h showed significantly less biofilm adherence on the vascularized surfaces. These results demonstrate the ability of an embedded lubricant-filled vascular network to improve the longevity of fouling-release surfaces.« less

Nanostructured aligned CNT platforms enhance the controlled release of a neurotrophic protein from polypyrrole

NASA Astrophysics Data System (ADS)

Thompson, Brianna C.; Chen, Jun; Moulton, Simon E.; Wallace, Gordon G.

2010-04-01

An aligned CNT array membrane electrode has been used as a nanostructured supporting platform for polypyrrole (PPy) films, exhibiting significant improvement in the controlled release of neurotrophin. In terms of linearity of release, stimulated to unstimulated control of NT-3 release and increased mass and % release of incorporated NT-3, the nanostructured material performed more favourably than the flat PPy film.

Polyurethane acrylates as effective substrates for sustained in vitro culture of human myotubes.

PubMed

Andriani, Yosephine; Chua, Jason Min-Wen; Chua, Benjamin Yan-Jiang; Phang, In Yee; Shyh-Chang, Ng; Tan, Wui Siew

2017-07-15

Muscular disease has debilitating effects with severe damage leading to death. Our knowledge of muscle biology, disease and treatment is largely derived from non-human cell models, even though non-human cells are known to differ from human cells in their biochemical responses. Attempts to develop highly sought after in vitro human cell models have been plagued by early cell delamination and difficulties in achieving human myotube culture in vitro. In this work, we developed polyurethane acrylate (PUA) materials to support long-term in vitro culture of human skeletal muscle tissue. Using a constant base with modulated crosslink density we were able to vary the material modulus while keeping surface chemistry and roughness constant. While previous studies have focused on materials that mimic soft muscle tissue with stiffness ca. 12kPa, we investigated materials with tendon-like surface moduli in the higher 150MPa to 2.4GPa range, which has remained unexplored. We found that PUA of an optimal modulus within this range can support human myoblast proliferation, terminal differentiation and sustenance beyond 35days, without use of any extracellular protein coating. Results show that PUA materials can serve as effective substrates for successful development of human skeletal muscle cell models and are suitable for long-term in vitro studies. We developed polyurethane acrylates (PUA) to modulate the human skeletal muscle cell growth and maturation in vitro by controlling surface chemistry, morphology and tuning material's stiffness. PUA was able to maintain muscle cell viability for over a month without any detectable signs of material degradation. The best performing PUA prevented premature cell detachment from the substrate which often hampered long-term muscle cell studies. It also supported muscle cell maturation up to the late stages of differentiation. The significance of these findings lies in the possibility to advance studies on muscle cell biology, disease and therapy by using human muscle cells instead of relying on the widely used animal-based in vitro models. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Development of certified reference materials for electrolytes in human serum (GBW09124-09126).

PubMed

Feng, Liuxing; Wang, Jun; Cui, Yanjie; Shi, Naijie; Li, Haifeng; Li, Hongmei

2017-05-01

Three reference materials, at relatively low, middle, and high concentrations, were developed for analysis of the mass fractions of electrolytes (K, Ca, Na, Mg, Cl, and Li) in human serum. The reference materials were prepared by adding high purity chloride salts to normal human serum. The concentration range of the three levels is within ±20% of normal human serum. It was shown that 14 units with duplicate analysis is enough to demonstrate the homogeneity of these candidate reference materials. The statistical results also showed no significant trends in both short-term stability test for 1 week at 40 °C and long-term stability test for 14 months. The certification methods of the six elements include isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS), inductively coupled plasma optical emission spectroscopy (ICP-OES), atomic absorption spectroscopy (AAS), ion chromatography (IC), and ion-selective electrode (ISE). The certification methods were validated by international comparisons among a number of national metrology institutes (NMIs). The combined relative standard uncertainties of the property values were estimated by considering the uncertainties of the analytical methods, homogeneity, and stability. The range of the expanded uncertainties of all the elements is from 2.2% to 3.9%. The certified reference materials (CRMs) are primarily intended for use in the calibration and validation of procedures in clinical analysis for the determination of electrolytes in human serum or plasma. Graphical Abstract Certified reference materials for K, Ca, Mg, Na, Cl and Li in human serum (GBW09124-09126).

Apollo experience report: The problem of stress-corrosion cracking

NASA Technical Reports Server (NTRS)

Johnson, R. E.

1973-01-01

Stress-corrosion cracking has been the most common cause of structural-material failures in the Apollo Program. The frequency of stress-corrosion cracking has been high and the magnitude of the problem, in terms of hardware lost and time and money expended, has been significant. In this report, the significant Apollo Program experiences with stress-corrosion cracking are discussed. The causes of stress-corrosion cracking and the corrective actions are discussed, in terminology familiar to design engineers and management personnel, to show how stress-corrosion cracking can be prevented.

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.

Effects of Impression Material, Impression Tray Type, and Type of Partial Edentulism on the Fit of Cobalt-Chromium Partial Denture Frameworks on Initial Clinical Insertion: A Retrospective Clinical Evaluation.

PubMed

Baig, Mirza Rustum; Akbar, Jaber Hussain; Qudeimat, Muawia; Omar, Ridwaan

2018-02-15

To evaluate the effects of impression material, impression tray type, and type of partial edentulism (ie, Kennedy class) on the accuracy of fit of cobalt-chromium (Co-Cr) partial removable dental prostheses (PRDP) in terms of the number of fabricated frameworks required until the attainment of adequate fit. Electronic case documentations of 120 partially edentulous patients provided with Co-Cr PRDP treatment for one or both arches were examined. Statistical analyses of data were performed using analysis of variance and Tukey honest significant difference test to compare the relationships between the different factors and the number of frameworks that needed to be fabricated for each patient (α = .05). Statistical analysis of data derived from 143 records (69 maxillary and 74 mandibular) revealed no significant correlation between impression material, tray type, or Kennedy class and the number of construction attempts for the pooled or individual arch data (P ≥ .05). In PRDP treatment, alginate can be chosen as a first-choice material, and metal stock trays can be a preferred option for making final impressions to fabricate Co-Cr frameworks.

Polymer-Based Nitric Oxide Therapies: Recent Insights for Biomedical Applications

PubMed Central

Jen, Michele C.; Serrano, María C.; van Lith, Robert

2014-01-01

Since the discovery of nitric oxide (NO) in the 1980s, this cellular messenger has been shown to participate in diverse biological processes such as cardiovascular homeostasis, immune response, wound healing, bone metabolism, and neurotransmission. Its beneficial effects have prompted increased research in the past two decades, with a focus on the development of materials that can locally release NO. However, significant limitations arise when applying these materials to biomedical applications. This Feature Article focuses on the development of NO-releasing and NO-generating polymeric materials (2006–2011) with emphasis on recent in vivo applications. Results are compared and discussed in terms of NO dose, release kinetics, and biological effects, in order to provide a foundation to design and evaluate new NO therapies. PMID:25067935

Optimization of a high-pressure pore water extraction device.

PubMed

Cyr, Martin; Daidié, Alain

2007-02-01

High-pressure squeezing is a technique used for the extraction of the pore water of porous materials such as sediments, soils, rocks, and concrete. The efficiency of extraction depends on the maximum pressures on the materials. This article presents the design of a high-pressure device reaching an axial pressure of 1000 MPa which has been developed to improve the efficiency of extraction. The increase in squeezing pressure implies high stresses inside the chamber, so specialized expertise was required to design a safe, functional device that could withstand pressures significantly higher than common laboratory equipment. The design includes finite element calculations, selection of appropriate materials, and descriptive construction details for the apparatus. It also includes an experimental study of the performance of the apparatus in terms of extraction efficiency.

Microbial ranking of porous packaging materials (exposure chamber method), ASTM method: collaborative study.

PubMed

Placencia, A M; Peeler, J T

1999-01-01

A collaborative study involving 11 laboratories was conducted to measure the microbial barrier effectiveness of porous medical packaging. Two randomly cut samples from each of 6 commercially available porous materials and one positive and one negative control were tested by one operator in each of 11 laboratories. Microbial barrier effectiveness was measured in terms of logarithm reduction value (LRV), which reflects the log10 microbial penetration of the material being tested. The logarithm of the final concentration is subtracted from that of the initial concentration to obtain the LRV. Thus the higher the LRV, the better the barrier. Repeatability standard deviations ranged from 6.42 to 16.40; reproducibility standard deviations ranged from 15.50 to 22.70. Materials B(53), C(50), D(CT), and E(45MF) differ significantly from the positive control. The microbial ranking of porous packaging materials (exposure chamber method), ASTM method, has been adopted First Action by AOAC INTERNATIONAL.

Comparison of retreatment ability of full-sequence reciprocating instrumentation and 360° rotary instrumentation.

PubMed

Capar, Ismail Davut; Gok, Tuba; Orhan, Ezgi

2015-12-01

The purpose of the present study was to investigate the amount of root canal filling material after root canal filling removal with 360° rotary instrumentation or reciprocating motion with the same file sequence. Root canals of the 36 mandibular premolars were shaped with ProTaper Universal instruments up to size F2 and filled with corresponding single gutta-percha cone and sealer. The teeth were assigned to two retreatment groups (n = 18): group 1 360° rotational motion and group 2 reciprocating motion of ATR Tecnika motors (1310° clockwise and 578° counterclockwise). Retreatment procedure was performed with ProTaper Universal retreatment files with a sequence of D1-3 and ProTaper Universal F3 instruments. Total time required to remove filling material were recorded. Remaining filling material was examined under stereomicroscope at ×8 magnification. The data were analysed statistically using the Mann-Whitney U test, and testing was performed at 95 % confidence level (p < 0.05). There were no significant differences between the groups (p > 0.05) in terms of remaining filling material. The total time required for retreatment was shorter in 360° rotational motion group compared to reciprocating motion group (p < 0.05). Both continuous rotation and reciprocating motion showed similar effectiveness in terms of root canal filling material removal. Using ProTaper Universal retreatment instruments with reciprocating motion of ATR motor and conventional rotary motion have similar efficacy in root canal filling removal.

Nanostructured Bulk Thermoelectric Generator for Efficient Power Harvesting for Self-powered Sensor Networks

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

Zhang, Yanliang; Butt, Darryl; Agarwal, Vivek

2015-07-01

The objective of this Nuclear Energy Enabling Technology research project is to develop high-efficiency and reliable thermoelectric generators for self-powered wireless sensors nodes utilizing thermal energy from nuclear plant or fuel cycle. The power harvesting technology has crosscutting significance to address critical technology gaps in monitoring nuclear plants and fuel cycle. The outcomes of the project will lead to significant advancement in sensors and instrumentation technology, reducing cost, improving monitoring reliability and therefore enhancing safety. The self-powered wireless sensor networks could support the long-term safe and economical operation of all the reactor designs and fuel cycle concepts, as well asmore » spent fuel storage and many other nuclear science and engineering applications. The research is based on recent breakthroughs in high-performance nanostructured bulk (nanobulk) thermoelectric materials that enable high-efficiency direct heat-to-electricity conversion over a wide temperature range. The nanobulk thermoelectric materials that the research team at Boise State University and University of Houston has developed yield up to a 50% increase in the thermoelectric figure of merit, ZT, compared with state-of-the-art bulk counterparts. This report focuses on the selection of optimal thermoelectric materials for this project. The team has performed extensive study on two thermoelectric materials systems, i.e. the half-Heusler materials, and the Bismuth-Telluride materials. The report contains our recent research results on the fabrication, characterization and thermoelectric property measurements of these two materials.« less

17 CFR 229.1108 - (Item 1108) Servicers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... charged for such advances and terms of recovery by the servicer of such advances. To the extent material...) State how long the servicer has been servicing assets. Provide, to the extent material, a general... material terms of the servicing agreement and the servicer's duties regarding the asset-backed securities...

17 CFR 229.1108 - (Item 1108) Servicers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... charged for such advances and terms of recovery by the servicer of such advances. To the extent material...) State how long the servicer has been servicing assets. Provide, to the extent material, a general... material terms of the servicing agreement and the servicer's duties regarding the asset-backed securities...

17 CFR 229.1108 - (Item 1108) Servicers.

Code of Federal Regulations, 2014 CFR

2014-04-01

... charged for such advances and terms of recovery by the servicer of such advances. To the extent material...) State how long the servicer has been servicing assets. Provide, to the extent material, a general... material terms of the servicing agreement and the servicer's duties regarding the asset-backed securities...

17 CFR 229.1108 - (Item 1108) Servicers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... charged for such advances and terms of recovery by the servicer of such advances. To the extent material...) State how long the servicer has been servicing assets. Provide, to the extent material, a general... material terms of the servicing agreement and the servicer's duties regarding the asset-backed securities...

Maternal dental caries and pre-term birth: results from the EPIPAP study.

PubMed

Vergnes, Jean-Noel; Kaminski, Monique; Lelong, Nathalie; Musset, Anne-Marie; Sixou, Michel; Nabet, Cathy

2011-07-01

OBJECTIVE. The aim of this study was to analyse the association between maternal dental caries and pre-term birth (PTB), with a particular focus on the infection-suspected causes of pre-term births. MATERIALS AND METHODS. A secondary analysis was performed on data from the EPIPAP study, a French multi-centre case-control study. Cases were 1107 women giving birth to a singleton live-born infant before 37 weeks of gestation and controls were 1094 women delivering at 37 weeks or more. A sub-group of cases was defined as women with spontaneous labour and/or pre-term premature rupture of membranes (PPROM, n = 620). A full-mouth dental examination was performed after delivery. The main factor of interest was the presence of decay on at least one tooth. RESULTS. Crude associations between presence of tooth decay and PTB or spontaneous PTB/PPROM were significant (OR = 1.21 [1.01-1.45] and OR = 1.25 [1.01-1.55], respectively). After adjustment for two sets of potential confounders (four pre-term birth risk factors and four social characteristics), for periodontitis status and for inter-examiner variability, tooth decay was not significantly associated with either PTB or spontaneous PTB/PPROM (aOR = 1.10 [0.91-1.32] and aOR = 1.14 [0.91-1.42], respectively). CONCLUSIONS. This study failed to demonstrate a significant association between tooth decay and pre-term birth. However, future well-designed studies are needed to further assess the link between dental caries and adverse pregnancy outcomes.

Quantifying uncertainties in the structural response of SSME blades

NASA Technical Reports Server (NTRS)

Nagpal, Vinod K.

1987-01-01

To quantify the uncertainties associated with the geometry and material properties of a Space Shuttle Main Engine (SSME) turbopump blade, a computer code known as STAEBL was used. A finite element model of the blade used 80 triangular shell elements with 55 nodes and five degrees of freedom per node. The whole study was simulated on the computer and no real experiments were conducted. The structural response has been evaluated in terms of three variables which are natural frequencies, root (maximum) stress, and blade tip displacements. The results of the study indicate that only the geometric uncertainties have significant effects on the response. Uncertainties in material properties have insignificant effects.

Cosmochemistry: Understanding the Solar System through analysis of extraterrestrial materials

PubMed Central

MacPherson, Glenn J.; Thiemens, Mark H.

2011-01-01

Cosmochemistry is the chemical analysis of extraterrestrial materials. This term generally is taken to mean laboratory analysis, which is the cosmochemistry gold standard because of the ability for repeated analysis under highly controlled conditions using the most advanced instrumentation unhindered by limitations in power, space, or environment. Over the past 40 y, advances in technology have enabled telescopic and spacecraft instruments to provide important data that significantly complement the laboratory data. In this special edition, recent advances in the state of the art of cosmochemistry are presented, which range from instrumental analysis of meteorites to theoretical–computational and astronomical observations. PMID:22128323

Toxicity and environmental and economic performance of fly ash and recycled concrete aggregates use in concrete: A review.

PubMed

Kurda, Rawaz; Silvestre, José D; de Brito, Jorge

2018-04-01

This paper presents an overview of previous studies on the environmental impact (EI) and toxicity of producing recycled concrete aggregates (RCA), fly ash (FA), cement, superplasticizer, and water as raw materials, and also on the effect of replacing cement and natural aggregates (NA) with FA and RCA, respectively, on the mentioned aspects. EI and toxicity were analysed simultaneously because considering concrete with alternative materials as sustainable depends on whether their risk assessment is high. Therefore, this study mainly focuses on the cradle-to-gate EI of one cubic meter of concrete, namely abiotic depletion potential (ADP), global warming potential (GWP), ozone depletion potential (ODP), photochemical ozone creation (POCP), acidification potential (AP), eutrophication potential (EP), non-renewable energy (PE-NRe) and renewable energy (PE-Re). In terms of toxicity, leachability (chemical and ecotoxicological characterization) was considered. The results also include the economic performance of these materials, and show that the incorporation of FA in concrete significantly decreases the EI and cost of concrete. Thus, the simultaneous incorporation of FA and RCA decrease the EI, cost, use of landfill space and natural resources extraction. Nonetheless, the leaching metals of FA decrease when they are incorporated in concrete. Relative to FA, the incorporation of RCA does not significantly affect the EI and cost of concrete, but it significantly reduces the use of landfill space and the need of virgin materials.

Comparison of Wear Resistance of Hawley and Vacuum Formed Retainers: An in-vitro Study

PubMed Central

V, Moshkelgosha; M, Shomali; M, Momeni

2016-01-01

Statement of Problem: As a physical property, wear resistance of the materials used in the fabrication of orthodontic retainers play a significant role in the stability and long term use of the appliances. Objectives: To evaluate the wear resistance of two commonly used materials for orthodontic retainers: Acropars OP, i.e. a polymethyl methacrylate based material, and 3A-GS060, i.e. a polyethylene based material. Materials and Methods: For each material, 30 orthodontic retainers were made according to the manufacturers’ instructions and a 30×30×2 mm block was cut out from the mid- palatal area of each retainer. Each specimen underwent 1000 cycles of wear stimulation in a pin on disc machine. The depth of wear of each specimen was measured using a Nano Wizard II atomic force microscope in 3 random points of each specimen’s wear trough. The average of these three measurements was calculated and considered as mean value wear depth of each specimen (µm). Results: The mean wear depth was 6.10µm and 2.15µm for 3A-GS060 and Acropars OP groups respectively. Independent t-test showed a significant difference between the two groups (p < 0.001). The results show Polymethyl methacrylate base (Acropars) is more wear resistance than the polyethylene based material (3A-GS060). Conclusions: As the higher wear resistance of the fabrication material can improve the retainers’ survival time and its cost-effectiveness, VFRs should be avoided in situations that the appliance needs high wear resistance such as bite blocks opposing occlusal forces. PMID:28959750

Five-year evaluation of a low-shrinkage Silorane resin composite material: a randomized clinical trial.

PubMed

Schmidt, Malene; Dige, Irene; Kirkevang, Lise-Lotte; Vaeth, Michael; Hørsted-Bindslev, Preben

2015-03-01

The aim of the present study was to investigate the clinical performance of a low-shrinkage silorane-based composite material (Filtek™ Silorane, 3 M-Espe) by comparing it with a methacrylate-based composite material (Ceram•X™, Dentsply DeTrey). A number of 72 patients (158 restorations) participated in the study. After 5 years, a total of 107 restorations (52 Filtek™ Silorane, 55 Ceram•X™) in 48 patients were evaluated. Only class II restorations were included. All the restorations were placed by the same dentist, and the restorations were scored by one experienced dentist/evaluator. Materials were applied following the manufacturer's instructions. The primary outcome was marginal adaptation. Secondary outcomes were: marginal discoloration, approximal contact, anatomic form, fracture, secondary caries, and hypersensitivity. After 5 years, no statistically significant differences between the two materials were found in marginal adaptation either occlusally (p = 0.96) or approximally (p = 0.62). No statistically significant differences were found between the two materials in terms of approximal contact, anatomic form, fractures, or discoloration. Secondary caries was found in two teeth (Filtek™ Silorane). One tooth showed hypersensitivity (Ceram•X™). Restorations of both materials were clinically acceptable after 5 years. This study did not find any advantage of the silorane-based composite over the methacrylate-based composite, which indicates that the low-shrinkage of Filtek™ Silorane may not be a determinant factor for clinical success in class II cavities. This paper is the first to evaluate the 5-year clinical performance of a low-shrinkage composite material.

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

Effects of waste glass additions on quality of textile sludge-based bricks.

PubMed

Rahman, Ari; Urabe, Takeo; Kishimoto, Naoyuki; Mizuhara, Shinji

2015-01-01

This research investigated the utilization of textile sludge as a substitute for clay in brick production. The addition of textile sludge to a brick specimen enhanced its pores, thus reducing the quality of the product. However, the addition of waste glass to brick production materials improved the quality of the brick in terms of both compressive strength and water absorption. Maximum compressive strength was observed with the following composition of waste materials: 30% textile sludge, 60% clay and 10% waste glass. The melting of waste glass clogged up pores on the brick, which improved water absorption performance and compressive strength. Moreover, a leaching test on a sludge-based brick to which 10% waste glass did not detect significant heavy metal compounds in leachates, with the product being in conformance with standard regulations. The recycling of textile sludge for brick production, when combined with waste glass additions, may thus be promising in terms of both product quality and environmental aspects.

Neuropsychologic assessment of long-term survivors of childhood leukemia.

PubMed

Pfefferbaum-Levine, B; Copeland, D R; Fletcher, J M; Ried, H L; Jaffe, N; McKinnon, W R

1984-01-01

Thirty-two long-term survivors of childhood leukemia who were followed up at the University of Texas M. D. Anderson Hospital were evaluated with a battery of 17 neuropsychologic tests. These tests were selected to assess the development of cognitive skills and functions associated with brain impairment in children. Statistically significant differences were found between the group of children given CNS irradiation and the nonirradiated group on full-scale IQ and verbal IQ scores, mathematics skills, constructional skills, and memory for spatial material. Of particular interest was the absence of differences in language-based measures of verbal memory and the presence of group differences on measures of memory for spatial material. While the sample size was small, the findings delineate specific areas likely to be affected. These results indicate the need for caution when including cranial irradiation in CNS prophylaxis. When any CNS treatment is given, it seems appropriate that provisions be made for assessment and remediation of affected skills.

The High-Strain Rate Loading of Structural Biological Materials

NASA Astrophysics Data System (ADS)

Proud, W. G.; Nguyen, T.-T. N.; Bo, C.; Butler, B. J.; Boddy, R. L.; Williams, A.; Masouros, S.; Brown, K. A.

2015-10-01

The human body can be subjected to violent acceleration as a result of explosion caused by military ordinance or accident. Blast waves cause injury and blunt trauma can be produced by violent impact of objects against the human body. The long-term clinical manifestations of blast injury can be significantly different in nature and extent to those suffering less aggressive insult. Similarly, the damage seen in lower limbs from those injured in explosion incidents is in general more severe than those falling from height. These phenomena increase the need for knowledge of the short- and long-term effect of transient mechanical loading to the biological structures of the human body. This paper gives an overview of some of the results of collaborative investigation into blast injury. The requirement for time-resolved data, appropriate mechanical modeling, materials characterization and biological effects is presented. The use of a range of loading platforms, universal testing machines, drop weights, Hopkinson bars, and bespoke traumatic injury simulators are given.

Modeling approaches for characterizing and evaluating environmental exposure to engineered nanomaterials in support of risk-based decision making.

PubMed

Hendren, Christine Ogilvie; Lowry, Michael; Grieger, Khara D; Money, Eric S; Johnston, John M; Wiesner, Mark R; Beaulieu, Stephen M

2013-02-05

As the use of engineered nanomaterials becomes more prevalent, the likelihood of unintended exposure to these materials also increases. Given the current scarcity of experimental data regarding fate, transport, and bioavailability, determining potential environmental exposure to these materials requires an in depth analysis of modeling techniques that can be used in both the near- and long-term. Here, we provide a critical review of traditional and emerging exposure modeling approaches to highlight the challenges that scientists and decision-makers face when developing environmental exposure and risk assessments for nanomaterials. We find that accounting for nanospecific properties, overcoming data gaps, realizing model limitations, and handling uncertainty are key to developing informative and reliable environmental exposure and risk assessments for engineered nanomaterials. We find methods suited to recognizing and addressing significant uncertainty to be most appropriate for near-term environmental exposure modeling, given the current state of information and the current insufficiency of established deterministic models to address environmental exposure to engineered nanomaterials.

The theory of cyclic voltammetry of electrochemically heterogeneous surfaces: comparison of different models for surface geometry and applications to highly ordered pyrolytic graphite.

PubMed

Ward, Kristopher R; Lawrence, Nathan S; Hartshorne, R Seth; Compton, Richard G

2012-05-28

The cyclic voltammetry at electrodes composed of multiple electroactive materials, where zones of one highly active material are distributed over a substrate of a second, less active material, is investigated by simulation. The two materials are assumed to differ in terms of their electrochemical rate constants towards any given redox couple. For a one-electron oxidation or reduction, the effect on voltammetry of the size and relative surface coverages of the zones as well as the rate constant of the slower zone are considered for systems where it is much slower than the rate constant of the faster zones. The occurrence of split peak cyclic voltammetry where two peaks are observed in the forward sweep, is studied in terms of the diffusional effects present in the system. A number of surface geometries are compared: specifically the more active zones are modelled as long, thin bands, as steps in the surface, as discs, and as rings (similar to a partially blocked electrode). Similar voltammetry for the band, step and ring models is seen but the disc geometry shows significant differences. Finally, the simulation technique is applied to the modelling of highly-ordered pyrolytic graphite (HOPG) surface and experimental conditions under which it may be possible to observe split peak voltammetry are predicted.

Nanofluidics in two-dimensional layered materials: inspirations from nature.

PubMed

Gao, Jun; Feng, Yaping; Guo, Wei; Jiang, Lei

2017-08-29

With the advance of chemistry, materials science, and nanotechnology, significant progress has been achieved in the design and application of synthetic nanofluidic devices and materials, mimicking the gating, rectifying, and adaptive functions of biological ion channels. Fundamental physics and chemistry behind these novel transport phenomena on the nanoscale have been explored in depth on single-pore platforms. However, toward real-world applications, one major challenge is to extrapolate these single-pore devices into macroscopic materials. Recently, inspired partially by the layered microstructure of nacre, the material design and large-scale integration of artificial nanofluidic devices have stepped into a completely new stage, termed 2D nanofluidics. Unique advantages of the 2D layered materials have been found, such as facile and scalable fabrication, high flux, efficient chemical modification, tunable channel size, etc. These features enable wide applications in, for example, biomimetic ion transport manipulation, molecular sieving, water treatment, and nanofluidic energy conversion and storage. This review highlights the recent progress, current challenges, and future perspectives in this emerging research field of "2D nanofluidics", with emphasis on the thought of bio-inspiration.

Term Familiarity to indicate Perceived and Actual Difficulty of Text in Medical Digital Libraries.

PubMed

Leroy, Gondy; Endicott, James E

2011-10-01

With increasing text digitization, digital libraries can personalize materials for individuals with different education levels and language skills. To this end, documents need meta-information describing their difficulty level. Previous attempts at such labeling used readability formulas but the formulas have not been validated with modern texts and their outcome is seldom associated with actual difficulty. We focus on medical texts and are developing new, evidence-based meta-tags that are associated with perceived and actual text difficulty. This work describes a first tag, term familiarity , which is based on term frequency in the Google corpus. We evaluated its feasibility to serve as a tag by looking at a document corpus (N=1,073) and found that terms in blogs or journal articles displayed unexpected but significantly different scores. Term familiarity was then applied to texts and results from a previous user study (N=86) and could better explain differences for perceived and actual difficulty.

Polymer composites and porous materials prepared by thermally induced phase separation and polymer-metal hybrid methods

NASA Astrophysics Data System (ADS)

Yoon, Joonsung

The primary objective of this research is to investigate the morphological and mechanical properties of composite materials and porous materials prepared by thermally induced phase separation. High melting crystallizable diluents were mixed with polymers so that the phase separation would be induced by the solidification of the diluents upon cooling. Theoretical phase diagrams were calculated using Flory-Huggins solution thermodynamics which show good agreement with the experimental results. Porous materials were prepared by the extraction of the crystallized diluents after cooling the mixtures (hexamethylbenzene/polyethylene and pyrene/polyethylene). Anisotropic structures show strong dependence on the identity of the diluents and the composition of the mixtures. Anisotropic crystal growth of the diluents was studied in terms of thermodynamics and kinetics using DSC, optical microscopy and SEM. Microstructures of the porous materials were explained in terms of supercooling and dendritic solidification. Dual functionality of the crystallizable diluents for composite materials was evaluated using isotactic polypropylene (iPP) and compatible diluents that crystallize upon cooling. The selected diluents form homogeneous mixtures with iPP at high temperature and lower the viscosity (improved processability), which undergo phase separation upon cooling to form solid particles that function as a toughening agent at room temperature. Tensile properties and morphology of the composites showed that organic crystalline particles have the similar effect as rigid particles to increase toughness; de-wetting between the particle and iPP matrix occurs at the early stage of deformation, followed by unhindered plastic flow that consumes significant amount of fracture energy. The effect of the diluents, however, strongly depends on the identity of the diluents that interact with the iPP during solidification step, which was demonstrated by comparing tetrabromobisphenol-A and phthalic anhydride. A simple method to prepare composite surfaces that can change the wettability in response to the temperature change was proposed and evaluated. Composite surfaces prepared by nanoporous alumina templates filled with polymers showed surface morphology and wettability that depend on temperature. This effect is attributed to the significant difference in thermal conductivity and the thermal expansion coefficient between the alumina and the polymers. The reversibility in thermal response depends on the properties of the polymers.

Short-term hot hardness characteristics of rolling-element steels

NASA Technical Reports Server (NTRS)

Chevalier, J. L.; Dietrich, M. W.; Zaretsky, E. V.

1972-01-01

Short-term hot hardness studies were performed with five vacuum-melted steels at temperatures from 294 to 887 K (70 to 1140 F). Based upon a minimum Rockwell C hardness of 58, the temperature limitation on all materials studied was dependent on the initial room temperature hardness and the tempering temperature of each material. For the same room temperature hardness, the short-term hot hardness characteristics were identical and independent of material composition. An equation was developed to predict the short-term hardness at temperature as a function of initial room temperature hardness for AISI 52100, as well as the high-speed tool steels.

Predictions for Radiation Shielding Materials

NASA Technical Reports Server (NTRS)

Kiefer, Richard L.

2002-01-01

Radiation from galactic cosmic rays (GCR) and solar particle events (SPE) is a serious hazard to humans and electronic instruments during space travel, particularly on prolonged missions outside the Earth s magnetic fields. Galactic cosmic radiation (GCR) is composed of approx. 98% nucleons and approx. 2% electrons and positrons. Although cosmic ray heavy ions are 1-2% of the fluence, these energetic heavy nuclei (HZE) contribute 50% of the long-term dose. These unusually high specific ionizations pose a significant health hazard acting as carcinogens and also causing microelectronics damage inside spacecraft and high-flying aircraft. These HZE ions are of concern for radiation protection and radiation shielding technology, because gross rearrangements and mutations and deletions in DNA are expected. Calculations have shown that HZE particles have a strong preference for interaction with light nuclei. The best shield for this radiation would be liquid hydrogen, which is totally impractical. For this reason, hydrogen-containing polymers make the most effective practical shields. Shielding is required during missions in Earth orbit and possibly for frequent flying at high altitude because of the broad GCR spectrum and during a passage into deep space and LunarMars habitation because of the protracted exposure encountered on a long space mission. An additional hazard comes from solar particle events (SPEs) which are mostly energetic protons that can produce heavy ion secondaries as well as neutrons in materials. These events occur at unpredictable times and can deliver a potentially lethal dose within several hours to an unshielded human. Radiation protection for humans requires safety in short-term missions and maintaining career exposure limits within acceptable levels on future long-term exploration missions. The selection of shield materials can alter the protection of humans by an order of magnitude. If improperly selected, shielding materials can actually increase radiation damage due to penetration properties and nuclear fragmentation. Protecting space-borne microelectronics from single event upsets (SEUs) by transmitted radiation will benefit system reliability and system design cost by using optimal shield materials. Long-term missions on the surface of the Moon or Mars will require the construction of habitats to protect humans during their stay. One approach to the construction is to make structural materials from lunar or Martian regolith using a polymeric material as a binder. The hydrogen-containing polymers are considerably more effective for radiation protection than the regolith, but the combination minimizes the amount of polymer to be transported. We have made composites of simulated lunar regolith with two different polymers, LaRC-SI, a high-performance polyimide thermoset, and polyethylene, a thermoplastic.

Effect of silver-loaded PMMA on Streptococcus mutans in a drip flow reactor.

PubMed

Williams, Dustin L; Epperson, Richard Tyler; DeGrauw, Jeffery P; Nielsen, Mattias B; Taylor, Nicholas B; Jolley, Ryan D

2017-09-01

Orthodontic retention has been proposed as a life-long commitment for patients who desire to maintain straight teeth. However, the presence of foreign material increases risk of bacterial colonization and caries formation, of which Streptococcus mutans is a key contributor. Multiple studies have assessed the ability of silver to be added to base plate material and resist attachment of S. mutans. However, it does not appear that long-term washout in connection with biofilm growth under physiologically relevant conditions has been taken into consideration. In this study, silver was added to base plate material and exposed to short- or long-term washout periods. Materials were then assessed for their ability to resist biofilm formation of S. mutans using a drip flow reactor that modeled the human oral environment. Data indicated that silver was able to resist biofilm formation following short-term washout, but long-term washout periods resulted in a lack of ability to resist biofilm formation. These data will be important for future development of base plate materials to achieve long-term antimicrobial efficacy to reduce risk of caries formation and benefit patients in the long term. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2632-2639, 2017. © 2017 Wiley Periodicals, Inc.

10 CFR 40.41 - Terms and conditions of licenses.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false Terms and conditions of licenses. 40.41 Section 40.41 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF SOURCE MATERIAL Licenses § 40.41 Terms and... the regulations in this part shall confine his possession and use of source or byproduct material to...

Effects of initial iron corrosion rate on long-term performance of iron permeable reactive barriers: column experiments and numerical simulation.

PubMed

suk O, Jin; Jeen, Sung-Wook; Gillham, Robert W; Gui, Lai

2009-01-26

Column experiments and numerical simulation were conducted to test the hypothesis that iron material having a high corrosion rate is not beneficial for the long-term performance of iron permeable reactive barriers (PRBs) because of faster passivation of iron and greater porosity loss close to the influent face of the PRBs. Four iron materials (Connelly, Gotthart-Maier, Peerless, and ISPAT) were used for the column experiments, and the changes in reactivity toward cis-dichloroethene (cis-DCE) degradation in the presence of dissolved CaCO3 were evaluated. The experimental results showed that the difference in distribution of the accumulated precipitates, resulting from differences in iron corrosion rate, caused a difference in the migration rate of the cis-DCE profiles and a significant difference in the pattern of passivation, indicating a faster passivation in the region close to the influent end for the material having a higher corrosion rate. For the numerical simulation, the accumulation of secondary minerals and reactivity loss of iron were coupled using an empirically-derived relationship that was incorporated into a multi-component reactive transport model. The simulation results provided a reasonable representation of the evolution of iron reactivity toward cis-DCE treatment and the changes in geochemical conditions for each material, consistent with the observed data. The simulations for long-term performance were also conducted to further test the hypothesis and predict the differences in performance over a period of 40 years under typical groundwater conditions. The predictions showed that the cases of higher iron corrosion rates had earlier cis-DCE breakthrough and more reduction in porosity starting from near the influent face, due to more accumulation of carbonate minerals in that region. Therefore, both the experimental and simulation results appear to support the hypothesis and suggest that reactivity changes of iron materials resulting from evolution of geochemical conditions should be considered in the design of iron PRBs.

Characterization of Polyimide Foams for Ultra-Lightweight Space Structures

NASA Technical Reports Server (NTRS)

Meador, Michael (Technical Monitor); Hillman, Keithan; Veazie, David R.

2003-01-01

Ultra-lightweight materials have played a significant role in nearly every area of human activity ranging from magnetic tapes and artificial organs to atmospheric balloons and space inflatables. The application range of ultra-lightweight materials in past decades has expanded dramatically due to their unsurpassed efficiency in terms of low weight and high compliance properties. A new generation of ultra-lightweight materials involving advanced polymeric materials, such as TEEK (TM) polyimide foams, is beginning to emerge to produce novel performance from ultra-lightweight systems for space applications. As a result, they require that special conditions be fulfilled to ensure adequate structural performance, shape retention, and thermal stability. It is therefore important and essential to develop methodologies for predicting the complex properties of ultra-lightweight foams. To support NASA programs such as the Reusable Launch Vehicle (RLV), Clark Atlanta University, along with SORDAL, Inc., has initiated projects for commercial process development of polyimide foams for the proposed cryogenic tank integrated structure (see figure 1). Fabrication and characterization of high temperature, advanced aerospace-grade polyimide foams and filled foam sandwich composites for specified lifetimes in NASA space applications, as well as quantifying the lifetime of components, are immensely attractive goals. In order to improve the development, durability, safety, and life cycle performance of ultra-lightweight polymeric foams, test methods for the properties are constant concerns in terms of timeliness, reliability, and cost. A major challenge is to identify the mechanisms of failures (i.e., core failure, interfacial debonding, and crack development) that are reflected in the measured properties. The long-term goal of the this research is to develop the tools and capabilities necessary to successfully engineer ultra-lightweight polymeric foams. The desire is to reduce density at the material and structural levels, while at the same time maintaining or increasing mechanical and other properties.

An interim overview of LDEF materials findings

NASA Technical Reports Server (NTRS)

Stein, Brad A.

1992-01-01

The flight and retrieval of the National Aeronautics and Space Administration's Long Duration Exposure Facility (LDEF) provided an opportunity for the study of the low-Earth orbit (LEO) environment and long-duration space environmental effects (SEE) on materials that is unparalleled in the history of the U.S. Space Program. The remarkable flight attitude stability of LDEF enables specific analyses of various individual and combined effects of LEO environmental parameters on identical materials on the same space vehicle. This paper provides an overview of the interim LDEF materials findings of the Principal Investigators and the Materials Special Investigation Group. In general, the LDEF data is remarkably consistent; LDEF will provide a 'benchmark' for materials design data bases for satellites in low-Earth orbit. Some materials were identified to be encouragingly resistant to LEO SEE for 5.8 years; other 'space qualified' materials displayed significant environmental degradation. Molecular contamination was widespread; LDEF offers an unprecedented opportunity to provide a unified perspective of unmanned LEO spacecraft contamination mechanisms. New material development requirements for long-term LEO missions have been identified and current ground simulation testing methods/data for new, durable materials concepts can be validated with LDEF results. LDEF findings are already being integrated into the design of Space Station Freedom.

Geomorphic impacts of flash flooding in a forested headwater basin

NASA Astrophysics Data System (ADS)

Phillips, Jonathan D.

2002-12-01

Geomorphic impacts of a July 2001 flood in the Hungry Mother basin near Marion, Virginia, were examined to shed light on the relationships between channel characteristics and the frequency of channel-modifying discharges. Creeks in the study area have been observed for many years, with no significant channel changes since at least 1985. The 2001 flood had a recurrence interval of >200 years, and caused the only channel change, bank erosion, and transport of coarse channel material observed in recent decades. The paucity of fines in channels before or after the flood, and the absence of sub-sand sized material in the flood deposits, indicates that normal, frequent, well-below-bankfull flows are sufficient to transport the (apparently limited) supply of fines. The large particles transported during the 2001 flood after years of inactivity indicate that relatively rare floods are necessary to mobilize this material. This suggests the notion of a bimodal 'dominant' discharge. On the one hand frequent flows considerably below bankfull levels are sufficient to maintain the channel and prevent significant accumulation of fine sediments and organic matter. On the other hand, rare floods are necessary to transport the coarser bed material and erode channel banks. In the Hungry Mother area, bed material has no relationship to normal flows, or to flows with recurrence intervals on the order of 1-3 years. Bankfull discharge is apparently not related to either the maintenance or channel-changing dominant discharges. These results suggest that the use of channel dimensions and/or bed material as surrogate indicators of hydrologic regimes can be quite complicated, and that in some streams bankfull flow has no particular significance in terms of sediment transport and channel modifications.

Development of a Moldable, Biodegradable Polymeric Bone Repair Material

DTIC Science & Technology

1994-03-30

minimally encapsulated by fibrous tissue. Histomorphometric analysis of day 14 specimens showed a very mild foreign body response in terms of area. This...significant visual evidence of foreign body response seen for any Atrix test article. A mass of dense fibrotic tissue was found near the defect site...article in the defect and medullary cavity. The test article was minimally encapsulated by fibrotic tissue. Histomorphometric analysis showed this

How Big Was It? Getting at Yield

NASA Astrophysics Data System (ADS)

Pasyanos, M.; Walter, W. R.; Ford, S. R.

2013-12-01

One of the most coveted pieces of information in the wake of a nuclear test is the explosive yield. Determining the yield from remote observations, however, is not necessarily a trivial thing. For instance, recorded observations of seismic amplitudes, used to estimate the yield, are significantly modified by the intervening media, which varies widely, and needs to be properly accounted for. Even after correcting for propagation effects such as geometrical spreading, attenuation, and station site terms, getting from the resulting source term to a yield depends on the specifics of the explosion source model, including material properties, and depth. Some formulas are based on assumptions of the explosion having a standard depth-of-burial and observed amplitudes can vary if the actual test is either significantly overburied or underburied. We will consider the complications and challenges of making these determinations using a number of standard, more traditional methods and a more recent method that we have developed using regional waveform envelopes. We will do this comparison for recent declared nuclear tests from the DPRK. We will also compare the methods using older explosions at the Nevada Test Site with announced yields, material and depths, so that actual performance can be measured. In all cases, we also strive to quantify realistic uncertainties on the yield estimation.

An evaluation of biodegradable synthetic polyurethane foam in patients following septoplasty: a prospective randomized trial.

PubMed

Yilmaz, Mahmut Sinan; Guven, Mehmet; Elicora, Sultan Sevik; Kaymaz, Recep

2013-01-01

The purpose of this study is to examine the usability of biodegradable synthetic polyurethane foam (BSPF) after septoplasty by comparing it with Merocel and silicone intranasal splints as packing materials in terms of patient comfort and efficiency. A prospective, unmasked, randomized trial. A tertiary referral center. This study was designed to be a prospective, randomized clinical trial. Sixty-eight patients who underwent septoplasty were included in this study. The patients were randomized to receive Merocel, silicone intranasal septal splint (INS), or BSPF after septoplasty. Clinical efficacy on bleeding, pain, and subjective symptoms related to packing materials was evaluated. There was a statistically significant difference between the Merocel group and the other 2 groups in terms of bleeding and adhesion. The average score on the pain scale was 2.47 ± 1.01 for BSPF, 3.68 ± 1.27 for INS, and 6 ± 2.21 for Merocel. Scores on general satisfaction scales were 6.95 ± 1.42 for Merocel, 8.44 ± 2.12 for INS, and 8.28 ± 1.88 for BSPF. The efficacy of BSPF was comparable with that of Merocel and INS. Biodegradable synthetic polyurethane foam significantly reduced pain and patient discomfort during packing and removal, followed by INS, compared with Merocel.

Engineering long term clinical success of advanced ceramic prostheses.

PubMed

Rekow, Dianne; Thompson, Van P

2007-01-01

Biocompatability and, in some applications, esthetics make all-ceramic prostheses compelling choices but despite significant improvements in materials properties and toughening mechanisms, these still have significant failure rates. Factors that contribute to the degradation in strength and survival include material selection and prosthesis design which set the upper limit for performance. However, fabrication operations introduce damage that can be exacerbated by environmental conditions and clinical function. Using all-ceramic dental crowns as an example, experimentally derived models provide insight into the relationships between materials properties and initial critical loads to failure. Analysis of fabrication operations suggests strategies to minimize damage. Environmental conditions can create viscoplastic flow of supporting components which can contribute additional stress within the prosthesis. Fatigue is a particularly challenging problem, not only providing the energy to propagate existing damage but, when combined with the wet environment, can create new damage modes. While much is known, the influence of these new damage modes has not been completely elucidated. The role of complex prosthesis geometry and its interaction with other factors on damage initiation and propagation has yet to be well characterized.

Flexural and compressive mechanical behaviors of the porous titanium materials with entangled wire structure at different sintering conditions for load-bearing biomedical applications.

PubMed

He, Guo; Liu, Ping; Tan, Qingbiao; Jiang, Guofeng

2013-12-01

The entangled titanium materials with various porosities have been investigated in terms of the flexural and compressive mechanical properties and the deformation and failure modes. The effect of the sintering parameters on the mechanical properties and the porosity reduction has been comprehensively studied. The results indicate that both the flexural and compressive mechanical properties increase significantly as the porosity decreases. In the porosity range investigated the flexural elastic modulus is in the range of 0.05-6.33GPa, the flexural strength is in the range of 9.8-324.9MPa, the compressive elastic modulus is in the range of 0.03-2.25GPa, and the compressive plateau stress is in the range of 2.3-147.8MPa. The mechanical properties of the entangled titanium materials can be significantly improved by sintering, which increase remarkably as the sintering temperature and/or the sintering time increases. But on other hand, the sintering process can induce the porosity reduction due to the oxidation on the titanium wire surface. © 2013 Elsevier Ltd. All rights reserved.

Perspective for Fibre-Hybrid Composites in Wind Energy Applications

PubMed Central

2017-01-01

Increasing the efficiency of wind turbines will be vital for the wind energy sector to continue growing. The drive for increased efficiency is pushing turbine manufacturers to shift from glass fibre composite blades towards carbon/glass fibre-hybrid composite blades. This shift brings significant challenges in terms of optimising the design and understanding the failure of these new blade materials. This review therefore surveys the literature on fibre-hybrid composites, with an emphasis on aspects that are relevant for turbine blade materials. The literature on tensile, flexural, compressive, and fatigue performance is critically assessed and areas for future research are identified. Numerical simulations of fibre-hybrid composites have reached a reasonable maturity for tensile failure, but significant progress is required for flexural, compressive, and fatigue failure. Fatigue failure of fibre-hybrid composites in particular, requires more careful attention from both a modelling and experimental point of view. PMID:29117126

Enhancement of L-asparaginase production by isolated Bacillus circulans (MTCC 8574) using response surface methodology.

PubMed

Hymavathi, M; Sathish, T; Subba Rao, Ch; Prakasham, R S

2009-10-01

L-asparaginase production was optimized using isolated Bacillus circulans (MTCC 8574) under solid-state fermentation (SSF) using locally available agricultural waste materials. Among different agricultural materials (red gram husk, bengal gram husk, coconut, and groundnut cake), red gram husk gave the maximum enzyme production. A wide range of SSF parameters were optimized for maximize the production of L-asparaginase. Preliminary studies revealed that incubation temperature, moisture content, inoculum level, glucose, and L-asparagine play a vital role in enzyme yield. The interactive behavior of each of these parameters along with their significance on enzyme yield was analyzed using fractional factorial central composite design (FFCCD). The observed correlation coefficient (R(2)) was 0.9714. Only L-asparagine and incubation temperature, were significant in linear and quadratic terms. L-asparaginase yield improved from 780 to 2,322 U/gds which is more than 300% using FFCCD as a means of optimizing conditions.

Oxidation/volatilization rates in air for candidate fusion reactor blanket materials, PCA and HT-9

NASA Astrophysics Data System (ADS)

Piet, S. J.; Kraus, H. G.; Neilson, R. M.; Jones, J. L.

1986-11-01

Large uncertainties exist in the quantity of neutron-induced activation products that can be mobilized in potential fusion accidents. The accidental combination of high temperatures and oxidizing conditions might lead to mobilization of a significant amount of activation products from structural materials. Here, the volatilization of constituents of PCA and HT-9 resulting form oxidation in air was investigated. Tests were conducted in flowing air at temperatures from 600 to 1300°C for 1, 5, or 20 h. Elemental volatility was calculated in terms of the weight fraction of the element volatilized from the initial alloy. Molybdenum and manganese were the radiologically significant primary constituents most volatilized, suggesting that molybdenum and manganese should be minimized in fusion steel compositions. Higher chromium content appears beneficial in reducing hazards from mobile activation products. Scanning electron microscopy and energy dispersive spectroscopy were used to study the oxide layer on samples.

Perspective for Fibre-Hybrid Composites in Wind Energy Applications.

PubMed

Swolfs, Yentl

2017-11-08

Increasing the efficiency of wind turbines will be vital for the wind energy sector to continue growing. The drive for increased efficiency is pushing turbine manufacturers to shift from glass fibre composite blades towards carbon/glass fibre-hybrid composite blades. This shift brings significant challenges in terms of optimising the design and understanding the failure of these new blade materials. This review therefore surveys the literature on fibre-hybrid composites, with an emphasis on aspects that are relevant for turbine blade materials. The literature on tensile, flexural, compressive, and fatigue performance is critically assessed and areas for future research are identified. Numerical simulations of fibre-hybrid composites have reached a reasonable maturity for tensile failure, but significant progress is required for flexural, compressive, and fatigue failure. Fatigue failure of fibre-hybrid composites in particular, requires more careful attention from both a modelling and experimental point of view.

Ghrelin and obestatin plasma levels and ghrelin/obestatin prepropeptide gene polymorphisms in small for gestational age infants.

PubMed

Zhang, Shulian; Zhai, Guanpeng; Zhang, Jinping; Zhou, Jianguo; Chen, Chao

2014-12-01

To investigate plasma ghrelin and obestatin levels, and ghrelin/obestatin prepropeptide gene polymorphisms, in sequentially enrolled small for gestational age (SGA) infants. Neonates were sequentially enrolled into this study and were then subdivided into different groups, according to different study aims and availability of study materials. Consequently, plasma ghrelin and obestatin levels were measured in term SGA, term appropriate for gestational age (AGA), term large for gestational age (LGA), preterm SGA and preterm AGA neonates. Levels of both peptides were also measured in AGA infants of different gestational ages, and in term AGA neonates at different days following birth. Three ghrelin/obestatin prepropeptide gene single nucleotide polymorphisms (SNPs), Arg51Gln, Leu72Met, and Gln90Leu, were measured in neonates. The study involved a total cohort of 581 neonates. Out of 150 neonates (30 term AGA, 30 term SGA, 30 term LGA, 30 preterm AGA, and 30 preterm SGA), plasma obestatin levels were significantly higher in term SGA versus term LGA neonates (0.21 ± 0.02 ng/ml versus 0.17 ± 0.01 ng/ml, respectively). Out of a wider cohort, there were no significant differences in genotypes and allele frequencies of Arg51Gln, Leu72Met, and Gln90Leu SNPs between term SGA and AGA neonates, or between preterm SGA and AGA neonates. Ghrelin/obestatin prepropeptide polymorphisms were not found to be associated with SGA status in neonates; however, ghrelin and obestatin levels may be involved in growth and development. Further studies are required to understand the relationship between ghrelin, obestatin and prenatal development. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

29 CFR 1926.960 - Definitions applicable to this subpart.

Code of Federal Regulations, 2014 CFR

2014-07-01

... be so run. (k) Conductor. The term means a material, usually in the form of a wire, cable, or bus bar... rules, and those of less than 400 volts to ground may be considered as supply lines, if so run and... worked on. (oo) Unstable material. The term means earth material, other than running, that because of its...

16 CFR 303.1 - Terms defined.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Identification Act (approved September 2, 1958, 85th Congress, 2d Sess.; 15 U.S.C. 70, 72 Stat. 1717). (b) The... thereof. (n) The term elastic material means a fabric composed of yarn consisting of an elastomer or a... material mean any materials, used in the direct sale or direct offering for sale of textile products, that...

16 CFR 303.1 - Terms defined.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Identification Act (approved September 2, 1958, 85th Congress, 2d Sess.; 15 U.S.C. 70, 72 Stat. 1717). (b) The... thereof. (n) The term elastic material means a fabric composed of yarn consisting of an elastomer or a... material mean any materials, used in the direct sale or direct offering for sale of textile products, that...

16 CFR 303.1 - Terms defined.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Identification Act (approved September 2, 1958, 85th Congress, 2d Sess.; 15 U.S.C. 70, 72 Stat. 1717). (b) The... thereof. (n) The term elastic material means a fabric composed of yarn consisting of an elastomer or a... material mean any materials, used in the direct sale or direct offering for sale of textile products, that...

Deficits in verbal long-term memory and learning in children with poor phonological short-term memory skills.

PubMed

Gathercole, Susan E; Briscoe, Josie; Thorn, Annabel; Tiffany, Claire

2008-03-01

Possible links between phonological short-term memory and both longer term memory and learning in 8-year-old children were investigated in this study. Performance on a range of tests of long-term memory and learning was compared for a group of 16 children with poor phonological short-term memory skills and a comparison group of children of the same age with matched nonverbal reasoning abilities but memory scores in the average range. The low-phonological-memory group were impaired on longer term memory and learning tasks that taxed memory for arbitrary verbal material such as names and nonwords. However, the two groups performed at comparable levels on tasks requiring the retention of visuo-spatial information and of meaningful material and at carrying out prospective memory tasks in which the children were asked to carry out actions at a future point in time. The results are consistent with the view that poor short-term memory function impairs the longer-term retention and ease of learning of novel verbal material.

In vitro cytotoxicity of traditional versus contemporary dental ceramics.

PubMed

Messer, Regina L W; Lockwood, Petra E; Wataha, John C; Lewis, Jill B; Norris, Samuel; Bouillaguet, Serge

2003-11-01

The biocompatibility of new dental ceramics has not been assessed with the same scrutiny as has been applied to alloys and composites. Yet, the biocompatibility of ceramics is critical to the long-term success of dental prostheses because ceramics are in close contact with oral tissues for extended periods. Five dental ceramics (2 traditional feldspathic veneer porcelains [Vita Omega and Duceragold], 2 lithium disilicate pressable materials [Stylepress and Empress-2], and a pressable leucite-based material [Empress-1]) were tested for their ability to alter cellular mitochondrial dehydrogenase activity after fabrication using a tetrazolium assay, after aging for 2 weeks in a biologic solution and after post-aging polishing with either a fine diamond or diamond polishing paste. Cellular responses were compared with polytetrafluoroethylene controls (analysis of variance, Tukey pairwise post-hoc comparison, alpha=.05). The feldspathic porcelains caused only mild (<25% of controls) mitochondrial suppression regardless of aging or polishing. The pressable leucite-based material initially caused a 5% stimulation (not significant) of mitochondrial activity, which decreased significantly (P<.05) by 30% with aging to levels comparable to the feldspathic porcelains, and did not change with polishing. Both lithium disilicate materials caused an initial suppression of mitochondrial activity that decreased significantly with aging, but Empress-2 was severely cytotoxic initially (<20% of controls, P<.01), and became more cytotoxic again after polishing. Stylepress was less cytotoxic initially (85% of controls, not significant) and did not become cytotoxic again after polishing. Dental ceramics are not equivalent in their in vitro biologic effects, even within the same class of material, and biologic safety should not be assumed. Most ceramics caused only mild in vitro suppression of cell function to levels that would be acceptable on the basis of standards used to evaluate alloys and composites. However, 1 Li-disilicate material (Empress-2) exhibited cytotoxicity that would not be deemed biologically acceptable on the basis of prevailing empirical standards for dental alloys and composites.

Long-term effects of seven cleaning methods on light transmittance, surface roughness, and flexural modulus of polyurethane retainer material.

PubMed

Agarwal, Manika; Wible, Emily; Ramir, Tyler; Altun, Sibel; Viana, Grace; Evans, Carla; Lukic, Henry; Megremis, Spiro; Atsawasuwan, Phimon

2018-05-01

To evaluate the long-term effects of seven different cleaning methods on light transmittance, surface roughness, and flexural modulus of a polyurethane retainer material. Polyurethane retainer specimens (Vivera®, Align Technology Inc) (70 specimens, n = 10 per method, 50.8 mm × 12.7 mm × 1.0 mm) were exposed to seven cleaning methods twice a week for 6 months. Before treatment and after 6 months, light transmittance, surface roughness, and flexural modulus of the specimens were quantified. Qualitative assessment of randomly selected specimens from each solution was performed at baseline and after 6 months using a scanning electron microscope. Statistical analyses were performed at the .05 significance level. Of the three test variables, light transmittance through the specimens was the only one that changed significantly from baseline to 6 months for all cleaning solutions, with all of them causing a decrease. However, except for 0.6% sodium hypochlorite showing a change in surface roughness values and 2.5% vinegar and toothbrushing showing an increase in flexural modulus, none of the other four cleaning methods resulted in significant changes in surface roughness or flexural modulus values for the polyurethane specimens between baseline and after 6 months. Of the seven cleaning methods, Invisalign® cleaning crystals, Polident®, and Listerine® showed the least amount of change in light transmittance values for the polyurethane specimens over 6 months, and they had no effect on surface roughness and flexural modulus values.

Spatial Working Memory Ability in Individuals at Ultra High Risk for Psychosis

PubMed Central

Goghari, Vina M.; Brett, Caroline; Tabraham, Paul; Johns, Louise; Valmaggia, Lucia; Broome, Matthew; Woolley, James; Bramon, Elvira; Howes, Oliver

2014-01-01

The goal of this investigation was to clarify the nature of spatial working memory difficulties in individuals at ultra high risk (UHR) for psychosis. We evaluated spatial working memory and intelligence in 96 individuals at UHR for psychosis, 28 patients with first episode psychosis (FEP), and 23 healthy controls. Fourteen UHR individuals developed a psychotic disorder during follow-up. Compared to controls, the UHR group was impaired in both the short-term maintenance of material and in the effective use of strategy, but not more immediate memory. These impairments were not as severe as those in the FEP group, as the UHR group performed better than the FEP group. A similar pattern of results was found for the intelligence measures. Discriminant function analyses demonstrated short-term maintenance of material significantly differentiated the UHR and healthy control groups even when accounting for full scale intelligence quotient (IQ); whereas full scale IQ significantly differentiated the UHR and FEP groups and FEP and control groups. Notably, within the UHR group, impaired spatial working memory performance was associated with lower global functioning, but not full scale IQ. The subgroup of UHR individuals who later developed psychosis was not significantly more impaired on any aspect of working memory performance than the group of UHR individuals who did not develop psychosis. Given, the relationship between spatial working memory deficits and functional outcome, these results indicate that cognitive remediation could be useful in individuals at UHR for psychosis to potentially improve functioning. PMID:24398256

The use of Banyumas traditional art as analog sources of elementary school science materials

NASA Astrophysics Data System (ADS)

Handayani, L.; Nugroho, S. E.; Rohidi, T. R.; Wiyanto

2018-03-01

All various traditional arts of Banyumas area support this area to be one famous region located in the periphery of West and Central Java with its unique cultural identity. In science learning, these traditional arts are very important aspect which can be implemented as a source of analog by students thinking a science concept analogically. This paper discusses a kind of Banyumas traditional art: the ebeg, and its cultural characteristics which can play a significant role in supporting elementary school students’ analogical thinking of a science material. The method used were literature and documentary studies. It is concluded that the ebeg provides many cultural characteristics which can be used as analog of elementary school science material, in terms of its music player’s motion, kinds of musical instruments played and its dancer motion.

Carbon-doped Ge2Sb2Te5 phase change material: A candidate for high-density phase change memory application

NASA Astrophysics Data System (ADS)

Zhou, Xilin; Wu, Liangcai; Song, Zhitang; Rao, Feng; Zhu, Min; Peng, Cheng; Yao, Dongning; Song, Sannian; Liu, Bo; Feng, Songlin

2012-10-01

Carbon-doped Ge2Sb2Te5 material is proposed for high-density phase-change memories. The carbon doping effects on electrical and structural properties of Ge2Sb2Te5 are studied by in situ resistance and x-ray diffraction measurements as well as optical spectroscopy. C atoms are found to significantly enhance the thermal stability of amorphous Ge2Sb2Te5 by increasing the degree of disorder of the amorphous phase. The reversible electrical switching capability of the phase-change memory cells is improved in terms of power consumption with carbon addition. The endurance of ˜2.1 × 104 cycles suggests that C-doped Ge2Sb2Te5 film will be a potential phase-change material for high-density storage application.

A two-dimensional analytical modeling for channel potential and threshold voltage of short channel triple material symmetrical gate Stack (TMGS) DG-MOSFET

NASA Astrophysics Data System (ADS)

Tripathi, Shweta

2016-10-01

In the present work, a two-dimensional (2D) analytical framework of triple material symmetrical gate stack (TMGS) DG-MOSFET is presented in order to subdue the short channel effects. A lightly doped channel along with triple material gate having different work functions and symmetrical gate stack structure, showcases substantial betterment in quashing short channel effects to a good extent. The device functioning amends in terms of improved exemption to threshold voltage roll-off, thereby suppressing the short channel effects. The encroachments of respective device arguments on the threshold voltage of the proposed structure are examined in detail. The significant outcomes are compared with the numerical simulation data obtained by using 2D ATLAS™ device simulator to affirm and formalize the proposed device structure.

Enhancing Reactivity in Structural Energetic Materials

NASA Astrophysics Data System (ADS)

Glumac, Nick

2017-06-01

In many structural energetic materials, only a small fraction of the metal oxidizes, and yet this provides a significant boost in the overall energy release of the system. Different methodologies to enhance this reactivity include alloying and geometric modifications of microstructure of the reactive material (RM). In this presentation, we present the results of several years of systematic study of both chemical (alloy) and mechanical (geometry) effects on reactivity for systems with typical charge to case mass ratios. Alloys of aluminum with magnesium and lithium are considered, as these are common alloys in aerospace applications. In terms of geometric modifications, we consider surface texturing, inclusion of dense additives, and inclusion of voids. In all modifications, a measurable influence on output is observed, and this influence is related to the fragment size distribution measured from the observed residue. Support from DTRA is gratefully acknowledged.

Lanthanide co-ordination frameworks: Opportunities and diversity

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

Hill, Robert J.; Long, De-Liang; Hubberstey, Peter

2005-08-15

Significant successes have been made over recent years in preparing co-ordination framework polymers that show macroscopic material properties, but in the vast majority of cases this has been achieved with d-block metal-based systems. Lanthanide co-ordination frameworks also offer attractive properties in terms of their potential applications as luminescent, non-linear optical and porous materials. However, lanthanide-based systems have been far less studied to date than their d-block counterparts. One possible reason for this is that the co-ordination spheres of lanthanide cations are more difficult to control and, in the absence of design strategies for lanthanide co-ordination frameworks, it is significantly moremore » difficult to target materials with specific properties. However, this article highlights some of the exciting possibilities that have emerged from the earliest investigations in this field with new topological families of compounds being discovered from relatively simple framework components, including unusual eight, seven and five-connected framework systems. Our own research, as well as others, is leading to a much greater appreciation of the factors that control framework formation and the resultant observed topologies of these polymers. As this understanding develops targeting particular framework types will become more straightforward and the development of designed polyfunctional materials more accessible. Thus, it can be seen that lanthanide co-ordination frameworks have the potential to open up previously unexplored directions for materials chemistry. This article focuses on the underlying concepts for the construction of these enticing and potentially highly important materials.« less

Adjoint-based optimization of mechanical performance in polycrystalline materials and structures through texture control

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

Gu, Grace; Brown, Judith Alice; Bishop, Joseph E.

The texture of a polycrystalline material refers to the preferred orientation of the grains within the material. In metallic materials, texture can significantly affect the mechanical properties such as elastic moduli, yield stress, strain hardening, and fracture toughness. Recent advances in additive manufacturing of metallic materials offer the possibility in the not too distant future of controlling the spatial variation of texture. In this work, we investigate the advantages, in terms of mechanical performance, of allowing the texture to vary spatially. We use an adjoint-based gradient optimization algorithm within a finite element solver (COMSOL) to optimize several engineering quantities ofmore » interest in a simple structure (hole in a plate) and loading (uniaxial tension) condition. As a first step to general texture optimization, we consider the idealized case of a pure fiber texture in which the homogenized properties are transversely isotropic. In this special case, the only spatially varying design variables are the three Euler angles that prescribe the orientation of the homogenized material at each point within the structure. This work paves a new way to design metallic materials for tunable mechanical properties at the microstructure level.« less

Effects of adsorptive properties of biofilter packing materials on toluene removal.

PubMed

Oh, Dong Ik; Song, Jihyeon; Hwang, Sun Jin; Kim, Jae Young

2009-10-15

Various adsorptive materials, including granular activated carbon (GAC) and ground tire rubber (GTR), were mixed with compost in biofilters used for treating gaseous toluene, and the effects of the mixtures on the stability of biofilter performance were investigated. A transient loading test demonstrated that a sudden increase in inlet toluene loading was effectively attenuated in the compost/GAC biofilter, which was the most significant advantage of adding adsorptive materials to the biofilter packing media. Under steady conditions with inlet toluene loading rates of 18.8 and 37.5 g/m(3)/h, both the compost and the compost/GAC biofilters achieved overall toluene removal efficiencies greater than 99%. In the compost/GAC mixture, however, biodegradation activity declined as the GAC mass fraction increased. Because of the low water-holding capacity of GTR, the compost/ground tire mixture did not show a significant improvement in toluene removal efficiency throughout the entire operational period. Furthermore, nitrogen limitations affected system performance in all the biofilters, but an external nitrogen supply resulted in the recovery of the toluene removal efficiency only in the compost biofilter during the test periods. Consequently, the introduction of excessive adsorptive materials was unfavorable for long-term performance, suggesting that the mass ratio of the adsorptive materials in such mixtures should be carefully selected to achieve high and steady biofilter performance.

Long-term evolution of the impurity composition and impurity events with the ITER-like wall at JET

NASA Astrophysics Data System (ADS)

Coenen, J. W.; Sertoli, M.; Brezinsek, S.; Coffey, I.; Dux, R.; Giroud, C.; Groth, M.; Huber, A.; Ivanova, D.; Krieger, K.; Lawson, K.; Marsen, S.; Meigs, A.; Neu, R.; Puetterich, T.; van Rooij, G. J.; Stamp, M. F.; Contributors, JET-EFDA

2013-07-01

This paper covers aspects of long-term evolution of intrinsic impurities in the JET tokamak with respect to the newly installed ITER-like wall (ILW). At first the changes related to the change over from the JET-C to the JET-ILW with beryllium (Be) as the main wall material and tungsten (W) in the divertor are discussed. The evolution of impurity fluxes in the newly installed W divertor with respect to studying material migration is described. In addition, a statistical analysis of transient impurity events causing significant plasma contamination and radiation losses is shown. The main findings comprise a drop in carbon content (×20) (see also Brezinsek et al (2013 J. Nucl. Mater. 438 S303)), low oxygen content (×10) due to the Be first wall (Douai et al 2013 J. Nucl. Mater. 438 S1172-6) as well as the evolution of the material mix in the divertor. Initially, a short period of repetitive ohmic plasmas was carried out to study material migration (Krieger et al 2013 J. Nucl. Mater. 438 S262). After the initial 1600 plasma seconds the material surface composition is, however, still evolving. With operational time, the levels of recycled C are increasing slightly by 20% while the Be levels in the deposition-dominated inner divertor are dropping, hinting at changes in the surface layer material mix made of Be, C and W. A steady number of transient impurity events, consisting of W and constituents of inconel, is observed despite the increase in variation in machine operation and changes in magnetic configuration as well as the auxiliary power increase.

Quantifying the environmental impact of a Li-rich high-capacity cathode material in electric vehicles via life cycle assessment.

PubMed

Wang, Yuqi; Yu, Yajuan; Huang, Kai; Chen, Bo; Deng, Wensheng; Yao, Ying

2017-01-01

A promising Li-rich high-capacity cathode material (xLi 2 MnO 3 ·(1-x)LiMn 0.5 Ni 0.5 O 2 ) has received much attention with regard to improving the performance of lithium-ion batteries in electric vehicles. This study presents an environmental impact evaluation of a lithium-ion battery with Li-rich materials used in an electric vehicle throughout the life cycle of the battery. A comparison between this cathode material and a Li-ion cathode material containing cobalt was compiled in this study. The battery use stage was found to play a large role in the total environmental impact and high greenhouse gas emissions. During battery production, cathode material manufacturing has the highest environmental impact due to its complex processing and variety of raw materials. Compared to the cathode with cobalt, the Li-rich material generates fewer impacts in terms of human health and ecosystem quality. Through the life cycle assessment (LCA) results and sensitivity analysis, we found that the electricity mix and energy efficiency significantly influence the environmental impacts of both battery production and battery use. This paper also provides a detailed life cycle inventory, including firsthand data on lithium-ion batteries with Li-rich cathode materials.

Effect of long-term water immersion or thermal shock on mechanical properties of high-impact acrylic denture base resins.

PubMed

Sasaki, Hirono; Hamanaka, Ippei; Takahashi, Yutaka; Kawaguchi, Tomohiro

2016-01-01

The purpose of this study was to investigate the effect of long-term water immersion or thermal shock on the mechanical properties of high-impact acrylic denture base resins. Two high-impact acrylic denture base resins were selected for the study. Specimens of each denture base material tested were fabricated according to the manufacturers' instructions (n=10). The flexural strength at the proportional limit, the elastic modulus and the impact strength of the specimens were evaluated. The flexural strength at the proportional limit of the high-impact acrylic denture base resins did not change after six months' water immersion or thermocycling 50,000 times. The elastic moduli of the high-impact acrylic denture base resins significantly increased after six months' water immersion or thermocycling 50,000 times. The impact strengths of the high-impact acrylic denture base resins significantly decreased after water immersion or thermocycling as described above.

A United States perspective on long-term management of areas contaminated with radioactive materials.

PubMed

Jones, C Rick

2004-01-01

The US has far-reaching and extensive experience in the long-term management of areas contaminated with radioactive materials. This experience base includes the Department of Energy's continued follow-up with Hiroshima and Nagasaki from the 1940s at the Radiological Effects Research Foundation in Hiroshima, Japan, the long-term management of the Marshall Islands Programme, the clean-up of the US nuclear weapons complex and the ongoing management of accident sites such as in Palomares, Spain. This paper discusses the lessons learnt and best practices gained from this far-reaching and extensive experience in the long-term management of areas contaminated with radioactive materials. Copyright 2004 Oxford University Press

A Comparative Evaluation of Sorption, Solubility, and Compressive Strength of Three Different Glass Ionomer Cements in Artificial Saliva: An in vitro Study

PubMed Central

Bhatia, Hind P; Sood, Shveta; Sharma, Naresh

2017-01-01

Aim To evaluate and compare the sorption, solubility, and compressive strength of three different glass ionomer cements in artificial saliva - type IX glass ionomer cement, silver-reinforced glass ionomer cement, and zirconia-reinforced glass ionomer cement, so as to determine the material of choice for stress-bearing areas. Materials and methods A total of 90 cylindrical specimens (4 mm diameter and 6 mm height) were prepared for each material following the manufacturer’s instructions. After subjecting the specimens to thermocycling, 45 specimens were immersed in artificial saliva for 24 hours for compressive strength testing under a universal testing machine, and the other 45 were evaluated for sorption and solubility, by first weighing them by a precision weighing scale (W1), then immersing them in artificial saliva for 28 days and weighing them (W2), and finally dehydrating in an oven for 24 hours and weighing them (W3). Results Group III (zirconomer) shows the highest compressive strength followed by group II (Miracle Mix) and least compressive strength is seen in group I (glass ionomer cement type IX-Extra) with statistically significant differences between the groups. The sorption and solubility values in artificial saliva were highest for glass ionomer cement type IX - Extra-GC (group I) followed by zirconomer-Shofu (group III), and the least value was seen for Miracle Mix-GC (group II). Conclusion Zirconia-reinforced glass ionomer cement is a promising dental material and can be used as a restoration in stress-bearing areas due to its high strength and low solubility and sorption rate. It may be a substitute for silver-reinforced glass ionomer cement due to the added advantage of esthetics. Clinical significance This study provides vital information to pediatric dental surgeons on relatively new restorative materials as physical and mechanical properties of the new material are compared with conventional materials to determine the best suited material in terms of durability, strength and dimensional stability. This study will boost confidence among dental surgeons in terms of handling characteristics, cost effectiveness and success rate. This study will help clinically and scientifically; pediatric dental surgeons to use this material in stress-bearing areas in pediatric patients. How to cite this article Bhatia HP, Singh S, Sood S, Sharma N. A Comparative Evaluation of Sorption, Solubility, and Com-pressive Strength of Three Different Glass Ionomer Cements in Artificial Saliva: An in vitro Study. Int J Clin Pediatr Dent 2017;10(1):49-54. PMID:28377656

Comparison of Wear Resistance of Hawley and Vacuum Formed Retainers: An in-vitro Study.

PubMed

V, Moshkelgosha; M, Shomali; M, Momeni

2016-06-01

As a physical property, wear resistance of the materials used in the fabrication of orthodontic retainers play a significant role in the stability and long term use of the appliances. To evaluate the wear resistance of two commonly used materials for orthodontic retainers: Acropars OP, i.e. a polymethyl methacrylate based material, and 3A-GS060, i.e. a polyethylene based material. For each material, 30 orthodontic retainers were made according to the manufacturers' instructions and a 30×30×2 mm block was cut out from the mid- palatal area of each retainer. Each specimen underwent 1000 cycles of wear stimulation in a pin on disc machine. The depth of wear of each specimen was measured using a Nano Wizard II atomic force microscope in 3 random points of each specimen's wear trough. The average of these three measurements was calculated and considered as mean value wear depth of each specimen (µm). The mean wear depth was 6.10µm and 2.15µm for 3A-GS060 and Acropars OP groups respectively. Independent t-test showed a significant difference between the two groups ( p < 0.001). The results show Polymethyl methacrylate base (Acropars) is more wear resistance than the polyethylene based material (3A-GS060). As the higher wear resistance of the fabrication material can improve the retainers' survival time and its cost-effectiveness, VFRs should be avoided in situations that the appliance needs high wear resistance such as bite blocks opposing occlusal forces.

Characterization of viscoelastic response and damping of composite materials used in flywheel rotors

NASA Astrophysics Data System (ADS)

Chen, Jianmin

The long-term goal for spacecraft flywheel systems with higher energy density at the system level requires new and innovative composite material concepts. Multi-Direction Composite (MDC) offers significant advantages over traditional filament-wound and multi-ring press-fit filament-wound wheels in providing higher energy density (i.e., less mass), better crack resistance, and enhanced safety. However there is a lack of systematic characterization for dynamic properties of MDC composite materials. In order to improve the flywheel materials reliability, durability and life time, it is very important to evaluate the time dependent aging effects and damping properties of MDC material, which are significant dynamic parameter for vibration and sound control, fatigue endurance, and impact resistance. The physical aging effects are quantified based on a set of creep curves measured at different aging time or different aging temperature. One parameter (tau) curve fit was proposed to represent the relationship of aging time and aging temperature between different master curves. The long term mechanical behavior was predicted by obtained master curves. The time and temperature shift factors of matrix were obtained from creep curves and the aging time shift rate were calculated. The aging effects on composite are obtained from experiments and compared with prediction. The mechanical quasi-behavior of MDC composite was analyzed. The correspondence principle was used to relate quasi-static elastic properties of composite materials to time-dependent properties of its constituent materials (i.e., fiber and matrix). The Prony series combined with the multi-data fitting method was applied to inverse Laplace transform and to calculate the time dependent stiffness matrix effectively. Accelerated time-dependent deformation of two flywheel rim designs were studied for a period equivalent to 31 years and are compared with hoop reinforcement only composite. Damping of pure resin and T700/epoxy composite lamina and laminate in longitudinal and transverse directions were investigated experimentally and analytically. The effect of aging on damping was also studied by placing samples at 60°C in an oven for extended periods. Damping master curves versus frequency were constructed from individual curves at different temperatures based on the Arrhenius equation. The damping response of the composite lamina was used to predict the response of laminate composites. Analytical results give close numerical values to experimental results from damping of cantilever beam laminated composite samples.

A Characteristic Mode Analysis of Conductive Nanowires and Microwires Above a Lossy Dielectric Half-Space

NASA Astrophysics Data System (ADS)

Kiddle, Daniel S.

Nanowires possess extraordinary mechanical, thermoelectric and electromagnetic properties which led to their incorporation in a wide variety of applications. The purpose of this study is to investigate the effect of material on the electromagnetic response of these nanowires. We used the Method of Moments (MOM) for Arbitrarily Thin Wire (ATW) formulation as an efficient computational technique for calculating the electromagnetic response of nanowires. To explain the calculated electromagnetic response, we evoked the Characteristic Mode Analysis (CMA) which decomposes the current on the wire into a superposition of fundamental current modes. These modes are weighted by two coefficients: (i) the relative importance of each mode at a certain frequency, termed Modal Significance, and (ii) the level of coupling between the incident field and the mode termed the Modal Excitation Coefficient. In this, work we study how the wire's material affect the Modal Significance and the Modal Excitation Coefficient of nanowires. Our results show that the material of the nanowire has a strong effect on the resonance frequency, the bandwidth, and the overlap of the modes showing that the material of the nanowire can be used as a tuning factor to develop sensors with desired radiation characteristics. Nanowires are commonly grown vertically on a substrate and, therefore, we also study the effect of the presence of a lossy dielectric half-space on their electromagnetic response. To efficiently account for this interface, we utilize a modified Green's function using the rigorous Sommerfeld integrals. Our results show that the relative permittivity of the substrate decreases the resonance frequencies of the nanowires and significantly alters their radiation patterns. Most importantly, we find that, if the nanowire is near the interface, its evanescent field's couple to the dielectric half space leading to the majority of the scattered power radiated into the substrate with high directivity. The results of this thesis has the potential to quantify the electromagnetic response of vertical nanowires in their realistic environment as well as facilitate the incorporation of nanowires in novel sensing applications.

Determination of the long-term release of metal(loid)s from construction materials using DGTs.

PubMed

Schmukat, A; Duester, L; Ecker, D; Heininger, P; Ternes, T A

2013-09-15

Long-term leaching experiments are crucial to estimate the potential release of dangerous substances from construction materials. The application of Diffuse Gradients in Thin film (DGT) in static-batch experiments was tested to study the long-term release of metal(loid)s from construction materials for hydraulic engineering, for half a year. Long-term release experiments are essential to improve calculations of the life-time release for this materials. DGTs in batch experiments were found to be a space and labour efficient application, which enabled (i) to study, in a non-invasive manner, the total release of nine metal(loid)s for half a year, (ii) to differentiate between release mechanisms and (iii) to study mechanisms which were contrary to the release or caused experimental artefacts in the batch experiments. For copper slag (test material) it was found that eight metal(loid)s were released over the whole time period of 184 d. Cu, Ni and Pb were found to be released, predominantly caused by (the) weathering of sulphide minerals. Only for Zn a surface depletion mechanism was identified. The results from the long-term batch experiments deliver new information on the release of metal(loid)s during the life cycle of construction materials with regard to river basin management objectives. Copyright © 2013 Elsevier B.V. All rights reserved.

Long-Term Fracture Resistance of Simulated Immature Teeth Filled with Various Calcium Silicate-Based Materials.

PubMed

Guven, Yeliz; Tuna, Elif Bahar; Dincol, M Emir; Ozel, Emre; Yilmaz, Bulent; Aktoren, Oya

2016-01-01

Objective. The aim of this in vitro study was to evaluate the long-term fracture resistance of simulated human immature permanent teeth filled with BioAggregate™ (BA), mineral trioxide aggregate (MTA), and EndoSequence® Root Repair Material (ERRM). Material and Methods. 40 teeth, simulated to average root length of 13 ± 1 mm (Cvek's stage 3), were included in the study. The teeth were randomly divided into four groups: Group 1: DiaRoot® BA, Group 2: MTA-Plus™ (MTA-P), Group 3: MTA-Angelus (MTA-A), and Group 4: ERRM. The root canal filling materials were applied according to the manufacturers' instructions. After 24 months of incubation, the roots of the teeth were embedded in acrylic blocks and subjected to fracture testing. The resultant data were analyzed statistically by Kruskal-Wallis and Mann-Whitney U tests. Results. Mean (±SD) failure loads (MPa) were 20.46 ± 2.53 for BA, 18.88 ± 5.13 for MTA-P, 14.12 ± 1.99 for MTA-A, and 17.65 ± 4.28 for ERRM groups. BA group exhibited the highest and MTA-A group showed the lowest resistance to fracture. Significant differences in fracture resistance were found between the groups of BA and MTA-A (p < 0.001), MTA-P and MTA-A (p < 0.05), and ERRM and MTA-A (p < 0.05). Conclusion. Within the limitations of this study, data suggests that BA-filled immature teeth demonstrate higher fracture resistance than other groups at 24 months appearing to be the most promising material tested.

Dynamic Effective Mass of Granular Media

NASA Astrophysics Data System (ADS)

Hsu, Chaur-Jian; Johnson, David L.; Ingale, Rohit A.; Valenza, John J.; Gland, Nicolas; Makse, Hernán A.

2009-02-01

We develop the concept of frequency dependent effective mass, Mtilde (ω), of jammed granular materials which occupy a rigid cavity to a filling fraction of 48%, the remaining volume being air of normal room condition or controlled humidity. The dominant features of Mtilde (ω) provide signatures of the dissipation of acoustic modes, elasticity, and aging effects in the granular medium. We perform humidity controlled experiments and interpret the data in terms of a continuum model and a “trap” model of thermally activated capillary bridges at the contact points. The results suggest that attenuation of acoustic waves in granular materials can be influenced significantly by the kinetics of capillary condensation between the asperities at the contacts.

Design of SERS nanoprobes for Raman imaging: materials, critical factors and architectures.

PubMed

Li, Mingwang; Qiu, Yuanyuan; Fan, Chenchen; Cui, Kai; Zhang, Yongming; Xiao, Zeyu

2018-05-01

Raman imaging yields high specificity and sensitivity when compared to other imaging modalities, mainly due to its fingerprint signature. However, intrinsic Raman signals are weak, thus limiting medical applications of Raman imaging. By adsorbing Raman molecules onto specific nanostructures such as noble metals, Raman signals can be significantly enhanced, termed surface-enhanced Raman scattering (SERS). Recent years have witnessed great interest in the development of SERS nanoprobes for Raman imaging. Rationally designed SERS nanoprobes have greatly enhanced Raman signals by several orders of magnitude, thus showing great potential for biomedical applications. In this review we elaborate on recent progress in design strategies with emphasis on material properties, modifying factors, and structural parameters.

Micrometeoroid/space debris effects on materials

NASA Technical Reports Server (NTRS)

Zwiener, James M.; Finckenor, Miria M.

1993-01-01

The Long Duration Exposure Facility (LDEF) micrometeoroid/space debris impact data has been reduced in terms that are convenient for evaluating the overall quantitative effect on material properties. Impact crater flux has been evaluated as a function of angle from velocity vector and as a function of crater size. This data is combined with spall data from flight and ground testing to calculate effective solar absorption and emittance values versus time. Results indicate that the surface damage from micrometeoroid/space debris does not significantly affect the overall surface optical thermal physical properties. Of course the local damage around impact craters radically alter optical properties. Damage to composites and solar cells on an overall basis was minimal.

Thiophene-Based Organic Semiconductors.

PubMed

Turkoglu, Gulsen; Cinar, M Emin; Ozturk, Turan

2017-10-24

Thiophene-based π-conjugated organic small molecules and polymers are the research subject of significant current interest owing to their potential use as organic semiconductors in material chemistry. Despite simple and similar molecular structures, the hitherto reported properties of thiophene-based organic semiconductors are rather diverse. Design of high performance organic semiconducting materials requires a thorough understanding of inter- and intra-molecular interactions, solid-state packing, and the influence of both factors on the charge carrier transport. In this chapter, thiophene-based organic semiconductors, which are classified in terms of their chemical structures and their structure-property relationships, are addressed for the potential applications as organic photovoltaics (OPVs), organic field-effect transistors (OFETs) and organic light emitting diodes (OLEDs).

Combined material recycling study with aesthetic of entropy and place making.

PubMed

Wen, Yifeng

2015-01-01

Green building is a hot topic today. The place making and urban cultures are also important issues in postindustrial society. The industrial heritage renovation projects provide a research opportunity in combination with both aspects. This paper tries to shed new light on this issue by interdisciplinary methods, to study six Guangzhou industrial heritage renovation projects, giving aesthetic values for six sites concerning place making and culture creation, especially giving an explanation for old building material's aesthetic performance in terms of concepts "entropy" and "archetype." The conclutions regard: the six places are brand spaces of "authentic Guangzhou" that make local experiential knowledge, emotional significance and creative communities in combination with historical and cultural narratives.

Comparison of Two Base Materials Regarding Their Effect on Root Canal Treatment Success in Primary Molars with Furcation Lesions

PubMed Central

Sonmez, Hayriye; Sari, Saziye

2016-01-01

Introduction. The aim of this study was to compare MTA with another base material, IRM, which is generally used on pulpal floor after root canal treatment, regarding their effect on the success of root canal treatment of primary teeth with furcation lesions. Materials and Methods. Fifty primary teeth with furcation lesions were divided into 2 groups. Following root canal treatment, the pulpal floor was coated with MTA in the experimental group and with IRM in the control group. Teeth were followed up considering clinical (pain, pathological mobility, tenderness to percussion and palpation, and any soft tissue pathology and sinus tract) and radiographical (pathological root resorption, reduced size or healing of existing lesion, and absence of new lesions at the interradicular or periapical area) criteria for 18 months. For the statistical analysis, Fisher's exact test and Pearson's chi-square tests were used and a p value of <0.05 was considered to be statistically significant. Results. Although there were no statistically significant differences between two groups in terms of treatment success, lesions healed significantly faster in the MTA group. Conclusion. In primary teeth with furcation lesions, usage of MTA on the pulpal floor following root canal treatment can be a better alternative since it induced faster healing. PMID:27957486

Comparison of Two Base Materials Regarding Their Effect on Root Canal Treatment Success in Primary Molars with Furcation Lesions.

PubMed

Arikan, Volkan; Sonmez, Hayriye; Sari, Saziye

2016-01-01

Introduction. The aim of this study was to compare MTA with another base material, IRM, which is generally used on pulpal floor after root canal treatment, regarding their effect on the success of root canal treatment of primary teeth with furcation lesions. Materials and Methods. Fifty primary teeth with furcation lesions were divided into 2 groups. Following root canal treatment, the pulpal floor was coated with MTA in the experimental group and with IRM in the control group. Teeth were followed up considering clinical (pain, pathological mobility, tenderness to percussion and palpation, and any soft tissue pathology and sinus tract) and radiographical (pathological root resorption, reduced size or healing of existing lesion, and absence of new lesions at the interradicular or periapical area) criteria for 18 months. For the statistical analysis, Fisher's exact test and Pearson's chi-square tests were used and a p value of <0.05 was considered to be statistically significant. Results. Although there were no statistically significant differences between two groups in terms of treatment success, lesions healed significantly faster in the MTA group. Conclusion. In primary teeth with furcation lesions, usage of MTA on the pulpal floor following root canal treatment can be a better alternative since it induced faster healing.

Thermal diffusivity of electrical insulators at high temperatures: Evidence for diffusion of bulk phonon-polaritons at infrared frequencies augmenting phonon heat conduction

NASA Astrophysics Data System (ADS)

Hofmeister, Anne M.; Dong, Jianjun; Branlund, Joy M.

2014-04-01

We show that laser-flash analysis measurements of the temperature (T) dependence of thermal diffusivity (D) for diverse non-metallic (e.g., silicates) single-crystals is consistently represented by D(T) = FT-G + HT above 298 K, with G ranging from 0.3 to 2, depending on structure, and H being ˜10-4 K-1 for 51 single-crystals, 3 polycrystals, and two glasses unaffected by disorder or reconstructive phase transitions. Materials exhibiting this behavior include complex silicates with variable amounts of cation disorder, perovskite structured materials, and graphite. The high-temperature term HT becomes important by ˜1300 K, above which temperature its contribution to D(T) exceeds that of the FT-G term. The combination of the FT-G and HT terms produces the nearly temperature independent high-temperature region of D previously interpreted as the minimal phonon mean free path being limited by the finite interatomic spacing. Based on the simplicity of the fit and large number of materials it represents, this finding has repercussions for high-temperature models of heat transport. One explanation is that the two terms describing D(T) are associated with two distinct microscopic mechanisms; here, we explore the possibility that the thermal diffusivity of an electrical insulator could include both a contribution of lattice phonons (the FT-G term) and a contribution of diffusive bulk phonon-polaritons (BPP) at infrared (IR) frequencies (the HT term). The proposed BPP diffusion exists over length scales smaller than the laboratory sample sizes, and transfers mixed light and vibrational energy at a speed significantly smaller than the speed of light. Our diffusive IR-BPP hypothesis is consistent with other experimental observations such as polarization behavior, dependence of D on the number of IR peaks, and H = 0 for Ge and Si, which lack IR fundamentals. A simple quasi-particle thermal diffusion model is presented to begin understanding the contribution from bulk phonon-polaritons to overall heat conduction.

10 CFR 40.28 - General license for custody and long-term care of uranium or thorium byproduct materials disposal...

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false General license for custody and long-term care of uranium or thorium byproduct materials disposal sites. 40.28 Section 40.28 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF SOURCE MATERIAL General Licenses § 40.28 General license for custody and...

29 CFR 570.65 - Occupations involved in the operations of circular saws, band saws, and guillotine shears (Order...

Code of Federal Regulations, 2010 CFR

2010-07-01

..., running over wheels or pulleys, and used for sawing materials. (6) The term guillotine shear shall mean a machine equipped with a movable blade operated vertically and used to shear materials. The term shall not... series of notches or teeth, running over wheels or pulleys, and used for sawing materials. Chain saw...

H2FIRST Reference Station Design Task: Project Deliverable 2-2

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

Pratt, Joseph; Terlip, Danny; Ainscough, Chris

2015-04-20

This report presents near-term station cost results and discusses cost trends of different station types. It compares various vehicle rollout scenarios and projects realistic near-term station utilization values using the station infrastructure rollout in California as an example. It describes near-term market demands and matches those to cost-effective station concepts. Finally, the report contains detailed designs for five selected stations, which include piping and instrumentation diagrams, bills of materials, and several site-specific layout studies that incorporate the setbacks required by NFPA 2, the National Fire Protection Association Hydrogen Technologies Code. This work identified those setbacks as a significant factor affectingmore » the ability to site a hydrogen station, particularly liquid stations at existing gasoline stations. For all station types, utilization has a large influence on the financial viability of the station.« less

Effect of an adhesive resin luting agent on the dowel-head retention of three different core materials.

PubMed

Aksoy, Gokhan; Cotert, H Serdar; Korkut, Levent

2005-05-01

A dowel-and-core restoration may fail due to failure at either the dowel-tooth or dowel head-core material interface. Long-term clinical success of a dowel-and-core restoration depends on retention of both the dowel to the tooth and the dowel head to the core material. Thus, strengthening of the dowel head-core interface is important. This study evaluated the retention between a prefabricated dowel and 3 different core materials with or without a dual-polymerized adhesive resin luting agent. Sixty prefabricated dowels (Gold Plated Anchorage Post) were divided into 3 groups (n=20) consisting of 1 of 3 core materials, amalgam (Standalloy F), light-polymerized resin composite (Clearfil Ray), or glass ionomer (Chelon-Silver). Each core group was divided into 2 subgroups (n=10), and a dual-polymerized adhesive resin luting agent (Panavia F) was applied to the dowel heads of 1 of these subgroups before application of the core material. The manufacturing procedure was standardized by using a plastic index (4.5-mm internal diameter and 5-mm height) and a custom-made dowel holder, which held the dowel head. Prepared specimens were stored in water at room temperature for 3 months and then loaded to fracture in a universal testing machine with a crosshead speed of 0.05 mm/min until failure. Bond strengths were recorded (MPa). Data were analyzed with 2-way analysis of variance (ANOVA) in a 2 x 3 factorial randomized design (alpha=.05). Afterward, core material differences were computed with 1-way ANOVA for both of the bonded and nonbonded groups. Post hoc multiple comparisons were made with the Dunnett C multiple range test. Dowel-head retention values (MPa) of the tested core materials (mean +/- SD) from the highest to the lowest were as follows: bonded amalgam core, 296.1 +/- 108; bonded composite core, 284.3 +/- 38.3; nonbonded composite core, 177.0 +/- 53.7; nonbonded amalgam core, 128.5 +/- 35.0; bonded glass-ionomer core (GIC), 128.0 +/- 24.5; nonbonded GIC, 61.8 +/- 13.3. Two-way ANOVA revealed significant differences between the core material groups and between the bonded and nonbonded groups (P <.001). The interaction between the core material and bond variables was also significant (P =.018). One-way ANOVA revealed statistically significant differences between the bonded (P <.001) and also between the nonbonded core material groups (P <.001). Post hoc multiple comparisons showed that the dowel-head retention of the GIC was significantly weaker than the post-head retention for amalgam and resin composite, whether bonded or not. Within the limitations of this study, the adhesive resin luting agent tested appeared to have a significant strengthening effect on the dowel-head retention of the core materials.

Stock dynamics and emission pathways of the global aluminum cycle

NASA Astrophysics Data System (ADS)

Müller, Daniel B.; Liu, Gang; Bangs, Colton

Climate change mitigation in the materials sector faces a twin challenge: satisfying rapidly rising global demand for materials while significantly curbing greenhouse-gas emissions. Process efficiency improvement and recycling can contribute to reducing emissions per material output; however, long-term material demand and scrap availability for recycling depend fundamentally on the dynamics of societies' stocks of products in use, an issue that has been largely neglected in climate science. Here, we show that aluminium in-use stock patterns set essential boundary conditions for future emission pathways, which has significant implications for mitigation priority setting. If developing countries follow industrialized countries in their aluminium stock patterns, a 50% emission reduction by 2050 below 2000 levels cannot be reached even under very optimistic recycling and technology assumptions. The target can be reached only if future global per-capita aluminium stocks saturate at a level much lower than that in present major industrialized countries. As long as global in-use stocks are growing rapidly, radical new technologies in primary production (for example, inert anode and carbon capture and storage) have the greatest impact in emission reduction; however, their window of opportunity is closing once the stocks begin to saturate and the largest reduction potential shifts to post-consumer scrap recycling.

Contact angle and surface free energy of experimental resin-based dental restorative materials after chewing simulation.

PubMed

Rüttermann, Stefan; Beikler, Thomas; Janda, Ralf

2014-06-01

To investigate contact angle and surface free energy of experimental dental resin composites containing novel delivery systems of polymeric hollow beads and low-surface tension agents after chewing simulation test. A delivery system of novel polymeric hollow beads differently loaded with two low-surface tension agents was used in different amounts to modify commonly formulated experimental dental resin composites. The non-modified resin was used as standard. Surface roughness Ra, contact angle Θ, total surface free energy γS, its apolar γS(LW), polar γS(AB), Lewis acid γS(+) and base γS(-) terms were determined and the results prior to and after chewing simulation test were compared. Significance was p<0.05. After chewing simulation Ra increased, Θ decreased, Ra increased for two test materials and γS decreased or remained constant for the standard or the test materials after chewing simulation. Ra of one test material was higher than of the standard, Θ and γS of the test materials remained lower than of the standard and, indicating their highly hydrophobic character (Θ≈60-75°, γS≈30mJm(-2)). γS(LW), and γS(-) of the test materials were lower than of the standard. Some of the test materials had lower γS(AB) and γS(+) than of the standard. Delivery systems based on novel polymeric hollow beads highly loaded with low-surface tension agents were found to significantly increase contact angle and thus to reduce surface free energy of experimental dental resin composites prior to and after chewing simulation test. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The role of water in slip casting

NASA Technical Reports Server (NTRS)

Mccauley, R. A.; Phelps, G. W.

1984-01-01

Slips and casting are considered in terms of physical and colloidal chemistry. Casting slips are polydisperse suspensions of lyophobic particles in water, whose degree of coagulation is controlled by interaction of flocculating and deflocculating agents. Slip casting rate and viscosity are functions of temperature. Slip rheology and response to deflocculating agents varies significantly as the kinds and amounts of colloid modifiers change. Water is considered as a raw material. Various concepts of water/clay interactions and structures are discussed. Casting is a de-watering operation in which water moves from slip to cast to mold in response to a potential energy termed moisture stress. Drying is an evaporative process from a free water surface.

Weathering of radiocaesium contamination on urban streets, walls and roofs.

PubMed

Andersson, K G; Roed, J; Fogh, C L

2002-01-01

Recent investigations in Russia have emphasised the significance of dose contributions from contamination on urban streets and roof pavings, and, typically to a lesser extent, walls in the urban environment. The crucial factor determining the magnitude of these contributions is the retention of the contamination by the different types of urban surface. Since the Chernobyl accident, a series of long-term field studies has been carried out on urban streets, walls and roofs, to examine the weathering processes of 137Cs on the various surface types. The derived time-functions are applied to estimate resultant long-term doses to inhabitants of an urban centre. The paper highlights the effect on caesium retention of surface material characteristics.

Diverse Electron-Induced Optical Emissions from Space Observatory Materials at Low Temperatures

NASA Technical Reports Server (NTRS)

Dennison, J.R.; Jensen, Amberly Evans; Wilson, Gregory; Dekany, Justin; Bowers, Charles W.; Meloy, Robert

2013-01-01

Electron irradiation experiments have investigated the diverse electron-induced optical and electrical signatures observed in ground-based tests of various space observatory materials at low temperature. Three types of light emission were observed: (i); long-duration cathodoluminescence which persisted as long as the electron beam was on (ii) short-duration (<1 s) arcing, resulting from electrostatic discharge; and (iii) intermediate-duration (100 s) glow-termed "flares". We discuss how the electron currents and arcing-as well as light emission absolute intensity and frequency-depend on electron beam energy, power, and flux and the temperature and thickness of different bulk (polyimides, epoxy resins, and silica glasses) and composite dielectric materials (disordered SiO2 thin films, carbon- and fiberglass-epoxy composites, and macroscopically-conductive carbon-loaded polyimides). We conclude that electron-induced optical emissions resulting from interactions between observatory materials and the space environment electron flux can, in specific circumstances, make significant contributions to the stray light background that could possibly adversely affect the performance of space-based observatories.

Esthetics and Biocompatibility of Composite Dental Laminates.

PubMed

D'Souza, Dsj; Kumar, M

2010-07-01

Advances in modern dental materials provide patients with a choice of natural looking veneers to provide esthetic restorations. These may be directly fabricated composite resin veneers or indirectly fabricated veneers. This study was carried out to evaluate the clinical effect of new generation indirect veneering composites and to compare them with veneers fabricated from direct composite restorations. The present study was carried out in the Prosthodontics department of a medical college. A total of forty patients requiring restoration of the anterior teeth using composite veneers were selected and either of the two materials was used to fabricate the veneers. Clinical evaluation was done for esthetics and periodontal health. Statistical analysis showed that there were no significant changes to the periodontal health during the period of the study. The evidence obtained from this study indicates that both direct as well as indirect composite materials had clinically acceptable outcomes in terms of restoration of esthetics. Biocompatibility with the periodontal tissues of both materials was also evident by the improvement in oral health indices used in the study.

Effects of insulator ablation on the operation of a quasi-steady MPD arc

NASA Technical Reports Server (NTRS)

Boyle, M. J.; Jahn, R. G.

1973-01-01

Multimegawatt operation of quasi-steady MPD arcjets can involve serious ablation of the insulator surfaces within the arc discharge chamber. Various degrees of insulator ablation manifest themselves by significantly perturbing the voltage-current characteristics and the exhaust velocity profiles. Voltage-current characteristics for two different insulator materials, Plexiglas and boron nitride, are interpreted in terms of an empirical Ohm's law. Use of the refractory insulator material eliminates the ablation-dominated nature of the terminal voltage, but the exhaust stream is still disturbed by insulator material. An Alfven critical velocity model can be applied to this influence of insulator ablation on exhaust velocity. Appropriate changes in the propellant injection geometry eliminate this influence and result in arcjet operation which is independent of insulator material. A particular combination of propellant injection geometries reduces the terminal voltage for a given current and mass flow while maintaining insulator-independent operation, thus implying an improvement in the overall efficiency of the device.

Redox-Flow Batteries: From Metals to Organic Redox-Active Materials.

PubMed

Winsberg, Jan; Hagemann, Tino; Janoschka, Tobias; Hager, Martin D; Schubert, Ulrich S

2017-01-16

Research on redox-flow batteries (RFBs) is currently experiencing a significant upturn, stimulated by the growing need to store increasing quantities of sustainably generated electrical energy. RFBs are promising candidates for the creation of smart grids, particularly when combined with photovoltaics and wind farms. To achieve the goal of "green", safe, and cost-efficient energy storage, research has shifted from metal-based materials to organic active materials in recent years. This Review presents an overview of various flow-battery systems. Relevant studies concerning their history are discussed as well as their development over the last few years from the classical inorganic, to organic/inorganic, to RFBs with organic redox-active cathode and anode materials. Available technologies are analyzed in terms of their technical, economic, and environmental aspects; the advantages and limitations of these systems are also discussed. Further technological challenges and prospective research possibilities are highlighted. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Computer-aided applications of nanoscale smart materials for biomedical applications.

PubMed

Rakesh, L; Howell, B A; Chai, M; Mueller, A; Kujawski, M; Fan, D; Ravi, S; Slominski, C

2008-10-01

Nanotechnology has the potential to impact the treatment of many diseases that currently plague society: cancer, AIDS, dementia of various kinds and so on. Nanoscale smart materials, such as carbon nanotubes, C(60), dendrimers and cyclodextrins, hold great promise for use in the development of better diagnostics, drug delivery and the alteration of biological function. Although experimentation is being used to explore the potential offered by these materials, it is by its very nature expensive in terms of time, resources and expertise. Insight with respect to the behavior of these materials in the presence of biological entities can be obtained much more rapidly by molecular dynamics simulation. Furthermore, the results of simulation may be used to guide experimentation so that it is much more productive than it might be in the absence of such information. The interactions of several nanoscale structures with biological macromolecules can already be probed effectively using molecular dynamics simulation. The results obtained should form the basis for significant new developments in the treatment of disease.

Nanostructured material-based biofuel cells: recent advances and future prospects.

PubMed

Zhao, Cui-E; Gai, Panpan; Song, Rongbin; Chen, Ying; Zhang, Jianrong; Zhu, Jun-Jie

2017-03-06

During the past decade, biofuel cells (BFCs) have emerged as an emerging technology on account of their ability to directly generate electricity from biologically renewable catalysts and fuels. Due to the boost in nanotechnology, significant advances have been accomplished in BFCs. Although it is still challenging to promote the performance of BFCs, adopting nanostructured materials for BFC construction has been extensively proposed as an effective and promising strategy to achieve high energy production. In this review, we presented the major novel nanostructured materials applied for BFCs and highlighted the breakthroughs in this field. Based on different natures of the bio-catalysts and electron transfer process at the bio-electrode surfaces, the fundamentals of BFC systems, including enzymatic biofuel cells (EBFCs) and microbial fuel cells (MFCs), have been elucidated. In particular, the principle of electrode materials design has been detailed in terms of enhancing electrical communications between biological catalysts and electrodes. Furthermore, we have provided the applications of BFCs and potential challenges of this technology.

High-quality collection and disposal of WEEE: Environmental impacts and resultant issues.

PubMed

Baxter, John; Lyng, Kari-Anne; Askham, Cecilia; Hanssen, Ole Jørgen

2016-11-01

Life cycle assessment of the collection, transport and recycling of various types of waste electrical and electronic equipment (WEEE) in Norway shows that small amounts of critical materials (refrigerants, precious/trace metals) are vital for the overall environmental accounts of the value chains. High-quality recycling ensures that materials and energy are effectively recovered from WEEE. This recovery means that responsible waste handling confers net environmental benefits in terms of global warming potential (GWP), for all types of WEEE analysed. For refrigeration equipment, the potential reduction of GWP by high-quality recycling is so large as to be of national significance. For all waste types, the magnitude of the net benefit from recovering materials and energy exceeds the negative consequences of irresponsible disposal. One outcome of this may be widespread misunderstanding of the need for recycling. Furthermore, framing public communication on recycling in terms of avoiding negative consequences, as is essentially universal, may not convey an appropriate message. The issue is particularly important where the consumer regards products as relatively disposable and environmentally benign, and/or where the "null option" of retaining the product at end-of-life is especially prevalent. The paper highlights the implications of all these issues for policy-makers, waste collectors and recyclers, and consumers. Copyright © 2016 Elsevier Ltd. All rights reserved.

Creep and cracking of concrete hinges: insight from centric and eccentric compression experiments.

PubMed

Schlappal, Thomas; Schweigler, Michael; Gmainer, Susanne; Peyerl, Martin; Pichler, Bernhard

2017-01-01

Existing design guidelines for concrete hinges consider bending-induced tensile cracking, but the structural behavior is oversimplified to be time-independent. This is the motivation to study creep and bending-induced tensile cracking of initially monolithic concrete hinges systematically. Material tests on plain concrete specimens and structural tests on marginally reinforced concrete hinges are performed. The experiments characterize material and structural creep under centric compression as well as bending-induced tensile cracking and the interaction between creep and cracking of concrete hinges. As for the latter two aims, three nominally identical concrete hinges are subjected to short-term and to longer-term eccentric compression tests. Obtained material and structural creep functions referring to centric compression are found to be very similar. The structural creep activity under eccentric compression is significantly larger because of the interaction between creep and cracking, i.e. bending-induced cracks progressively open and propagate under sustained eccentric loading. As for concrete hinges in frame-like integral bridge construction, it is concluded (i) that realistic simulation of variable loads requires consideration of the here-studied time-dependent behavior and (ii) that permanent compressive normal forces shall be limited by 45% of the ultimate load carrying capacity, in order to avoid damage of concrete hinges under sustained loading.

Robotic weld overlay coatings for erosion control

NASA Astrophysics Data System (ADS)

The erosion of materials by the impact of solid particles has received increasing attention during the past twenty years. Recently, research has been initiated with the event of advanced coal conversion processes in which erosion plays an important role. The resulting damage, termed Solid Particle Erosion (SPE), is of concern primarily because of the significantly increased operating costs which result in material failures. Reduced power plant efficiency due to solid particle erosion of boiler tubes and waterfalls has led to various methods to combat SPE. One method is to apply coatings to the components subjected to erosive environments. Protective weld overlay coatings are particularly advantageous in terms of coating quality. The weld overlay coatings are essentially immune to spallation due to a strong metallurgical bond with the substrate material. By using powder mixtures, multiple alloys can be mixed in order to achieve the best performance in an erosive environment. However, a review of the literature revealed a lack of information on weld overlay coating performance in erosive environments which makes the selection of weld overlay alloys a difficult task. The objective of this project is to determine the effects of weld overlay coating composition and microstructure on erosion resistance. These results will lead to a better understanding of erosion mitigation in CFB's.

Composite structural materials

NASA Technical Reports Server (NTRS)

Loewy, R.; Wiberley, S. E.

1986-01-01

Overall emphasis is on basic long-term research in the following categories: constituent materials, composite materials, generic structural elements, processing science technology; and maintaining long-term structural integrity. Research in basic composition, characteristics, and processing science of composite materials and their constituents is balanced against the mechanics, conceptual design, fabrication, and testing of generic structural elements typical of aerospace vehicles so as to encourage the discovery of unusual solutions to present and future problems. Detailed descriptions of the progress achieved in the various component parts of this comprehensive program are presented.

Theoretical analysis of oscillatory terms in lattice heat-current time correlation functions and their contributions to thermal conductivity

NASA Astrophysics Data System (ADS)

Pereverzev, Andrey; Sewell, Tommy

2018-03-01

Lattice heat-current time correlation functions for insulators and semiconductors obtained using molecular dynamics (MD) simulations exhibit features of both pure exponential decay and oscillatory-exponential decay. For some materials the oscillatory terms contribute significantly to the lattice heat conductivity calculated from the correlation functions. However, the origin of the oscillatory terms is not well understood, and their contribution to the heat conductivity is accounted for by fitting them to empirical functions. Here, a translationally invariant expression for the heat current in terms of creation and annihilation operators is derived. By using this full phonon-picture definition of the heat current and applying the relaxation-time approximation we explain, at least in part, the origin of the oscillatory terms in the lattice heat-current correlation function. We discuss the relationship between the crystal Hamiltonian and the magnitude of the oscillatory terms. A solvable one-dimensional model is used to illustrate the potential importance of terms that are omitted in the commonly used phonon-picture expression for the heat current. While the derivations are fully quantum mechanical, classical-limit expressions are provided that enable direct contact with classical quantities obtainable from MD.

Long-term stability and properties of zirconia ceramics for heavy duty diesel engine components

NASA Technical Reports Server (NTRS)

Larsen, D. C.; Adams, J. W.

1985-01-01

Physical, mechanical, and thermal properties of commercially available transformation-toughened zirconia are measured. Behavior is related to the material microstructure and phase assemblage. The stability of the materials is assessed after long-term exposure appropriate for diesel engine application. Properties measured included flexure strength, elastic modulus, fracture toughness, creep, thermal shock, thermal expansion, internal friction, and thermal diffusivity. Stability is assessed by measuring the residual property after 1000 hr/1000C static exposure. Additionally static fatigue and thermal fatigue testing is performed. Both yttria-stabilized and magnesia-stabilized materials are compared and contrasted. The major limitations of these materials are short term loss of properties with increasing temperature as the metastable tetragonal phase becomes more stable. Fine grain yttria-stabilized material (TZP) is higher strength and has a more stable microstructure with respect to overaging phenomena. The long-term limitation of Y-TZP is excessive creep deformation. Magnesia-stabilized PSZ has relatively poor stability at elevated temperature. Overaging, decomposition, and/or destabilization effects are observed. The major limitation of Mg-PSZ is controlling unwanted phase changes at elevated temperature.

Outstanding electrochemical performance of a graphene-modified graphite felt for vanadium redox flow battery application

NASA Astrophysics Data System (ADS)

González, Zoraida; Flox, Cristina; Blanco, Clara; Granda, Marcos; Morante, Juan R.; Menéndez, Rosa; Santamaría, Ricardo

2017-01-01

The development of more efficient electrode materials is essential to obtain vanadium redox flow batteries (VRFBs) with enhanced energy densities and to make these electrochemical energy storage devices more competitive. A graphene-modified graphite felt synthesized from a raw graphite felt and a graphene oxide water suspension by means of electrophoretic deposition (EPD) is investigated as a suitable electrode material in the positive side of a VRFB cell by means of cyclic voltammetry, impedance spectroscopy and charge/discharge experiments. The remarkably enhanced performance of the resultant hybrid material, in terms of electrochemical activity and kinetic reversibility towards the VO2+/VO2+, and mainly the markedly high energy efficiency of the VRFB cell (c.a. 95.8% at 25 mA cm-2) can be ascribed to the exceptional morphological and chemical characteristics of this tailored material. The 3D-architecture consisting of fibers interconnected by graphene-like sheets positively contributes to the proper development of the vanadium redox reactions and so represents a significant advance in the design of effective electrode materials.

Current perspectives of bio-ceramic technology in endodontics: calcium enriched mixture cement - review of its composition, properties and applications

PubMed Central

Nawal, Ruchika Roongta; Talwar, Sangeeta; Verma, Mahesh

2015-01-01

Advancements in bio-ceramic technology has revolutionised endodontic material science by enhancing the treatment outcome for patients. This class of dental materials conciliates excellent biocompatibility with high osseoconductivity that render them ideal for endodontic care. Few recently introduced bio-ceramic materials have shown considerable clinical success over their early generations in terms of good handling characteristics. Calcium enriched mixture (CEM) cement, Endosequence sealer, and root repair materials, Biodentine and BioAggregate are the new classes of bio-ceramic materials. The aim of this literature review is to present investigations regarding properties and applications of CEM cement in endodontics. A review of the existing literature was performed by using electronic and hand searching methods for CEM cement from January 2006 to December 2013. CEM cement has a different chemical composition from that of mineral trioxide aggregate (MTA) but has similar clinical applications. It combines the biocompatibility of MTA with more efficient characteristics, such as significantly shorter setting time, good handling characteristics, no staining of tooth and effective seal against bacterial leakage. PMID:25671207

Technology Assessment of Laser-Assisted Materials Processing in Space

NASA Technical Reports Server (NTRS)

Nagarathnam, Karthik; Taminger, Karen M. B.

2001-01-01

Lasers are useful for performing operations such as joining, machining, built-up freeform fabrication, shock processing, and surface treatments. These attributes are attractive for the supportability of longer-term missions in space due to the multi-functionality of a single tool and the variety of materials that can be processed. However, current laser technology also has drawbacks for space-based applications, specifically size, power efficiency, lack of robustness, and problems processing highly reflective materials. A review of recent laser developments will be used to show how these issues may be reduced and indicate where further improvement is necessary to realize a laser-based materials processing capability in space. The broad utility of laser beams in synthesizing various classes of engineering materials will be illustrated using state-of-the art processing maps for select lightweight alloys typically found on spacecraft. With the advent of recent breakthroughs in diode-pumped solid-state lasers and fiber optic technologies, the potential to perform multiple processing techniques is increasing significantly. Lasers with suitable wavelengths and beam properties have tremendous potential for supporting future space missions to the moon, Mars and beyond.

Searching for Sustainable and "Greener" Li-ion Batteries

ScienceCinema

Tarascon, Jean-Marie [University of Picardie at Aimens, France

2017-12-09

Lithium-ion batteries are strong candidates for powering upcoming generations of hybrid electric vehicles and plug-in hybrid electric vehicles. But improvements in safety must be achieved while keeping track of materials resources and abundances, as well as materials synthesis and recycling processes, all of which could inflict a heavy energy cost. Thus, electrode materials that have a minimum footprint in nature and are made via eco-efficient processes are sorely needed. The arrival of electrode materials based on minerals such as LiFePO4 (tryphilite) is a significant, but not sufficient, step toward the long-term demand for materials sustainability. The eco-efficient synthesis of LiFePO4 nanopowders via hydrothermal/ solvo-thermal processes using latent bases, structure directing templates, or other bio-related approaches will be presented in this talk. However, to secure sustainability and greeness, organic electrodes appear to be ideal candidates.... We took a fresh look at organic based electrodes; the results of this research into sequentially metal-organic-framework electrodes and Li-based organic electrodes (LixCyOz) will be reported and discussed.

Clinical and Oncological Value of Preoperative BMI in Gastric Cancer Patients: A Single Center Experience

PubMed Central

Voglino, Costantino; Di Mare, Giulio; Ferrara, Francesco; De Franco, Lorenzo; Roviello, Franco; Marrelli, Daniele

2015-01-01

Introduction. The impact of preoperative BMI on surgical outcomes and long-term survival of gastric cancer patients was investigated in various reports with contrasting results. Materials & Methods. A total of 378 patients who underwent a surgical resection for primary gastric cancer between 1994 and 2011 were retrospectively studied. Patients were stratified according to BMI into a normal group (<25, group A), an overweight group (25–30, group B), and an obesity group (≥30, group C). These 3 groups were compared according to clinical-pathological characteristics, surgical treatment, and long-term survival. Results. No significant correlations between BMI and TNM (2010), UICC stage (2010), Lauren's histological type, surgical results, lymph node dissection, and postoperative morbidity and mortality were observed. Factors related to higher BMI were male gender (P < 0.05), diabetes (P < 0.001), and serum blood proteins (P < 0.01). A trend to fewer lymph nodes retrieved during gastrectomy with lymphadenectomy in overweight patients (B and C groups) was observed, although not statistically significant. There was no difference in overall survival or disease-specific survival between the three groups. Conclusion. According to our data, BMI should not be considered a significant predictor of postoperative complications or long-term result in gastric cancer patients. PMID:25759721

Effects of pipe materials on chlorine-resistant biofilm formation under long-term high chlorine level.

PubMed

Zhu, Zebing; Wu, Chenguang; Zhong, Dan; Yuan, Yixing; Shan, Lili; Zhang, Jie

2014-07-01

Drinking water distribution systems are composed of various pipe materials and may harbor biofilms even in the continuous presence of disinfectants. Biofilms formation on five pipe materials (copper (Cu), polyethylene (PE), stainless steel (STS), cast iron (CI), and concrete-coated polycarbonate (CP)) within drinking water containing 1.20 mg/L free chlorine, was investigated by flow cytometry, heterotrophic plate counts, and denaturing gradient gel electrophoresis analysis. Results showed that the biofilms formation varied in pipe materials. The biofilm formed on CP initially emerged the highest biomass in 12 days, but CI presented the significantly highest biomass after 28 days, and Cu showed the lowest bacterial numbers before 120 days, while STS expressed the lowest bacterial numbers after 159 days. In the biofilm community structure, Moraxella osloensis and Sphingomonas sp. were observed in all the pipe materials while Bacillus sp. was detected except in the CP pipe and Stenotrophomonas maltophila was found from three pipe materials (Cu, PE, and STS). Other bacteria were only found from one or two pipe materials. It is noteworthy that there are 11 opportunistic pathogens in the 17 classified bacterial strains. This research has afforded crucial information regarding the influence of pipe materials on chlorine-resistant biofilm formation.

Review on the Processing and Properties of Polymer Nanocomposites and Nanocoatings and Their Applications in the Packaging, Automotive and Solar Energy Fields

PubMed Central

Müller, Kerstin; Bugnicourt, Elodie; Latorre, Marcos; Jorda, Maria; Echegoyen Sanz, Yolanda; Lagaron, José M.; Miesbauer, Oliver; Bianchin, Alvise; Hankin, Steve; Bölz, Uwe; Pérez, Germán; Jesdinszki, Marius; Lindner, Martina; Scheuerer, Zuzana; Castelló, Sara; Schmid, Markus

2017-01-01

For the last decades, nanocomposites materials have been widely studied in the scientific literature as they provide substantial properties enhancements, even at low nanoparticles content. Their performance depends on a number of parameters but the nanoparticles dispersion and distribution state remains the key challenge in order to obtain the full nanocomposites’ potential in terms of, e.g., flame retardance, mechanical, barrier and thermal properties, etc., that would allow extending their use in the industry. While the amount of existing research and indeed review papers regarding the formulation of nanocomposites is already significant, after listing the most common applications, this review focuses more in-depth on the properties and materials of relevance in three target sectors: packaging, solar energy and automotive. In terms of advances in the processing of nanocomposites, this review discusses various enhancement technologies such as the use of ultrasounds for in-process nanoparticles dispersion. In the case of nanocoatings, it describes the different conventionally used processes as well as nanoparticles deposition by electro-hydrodynamic processing. All in all, this review gives the basics both in terms of composition and of processing aspects to reach optimal properties for using nanocomposites in the selected applications. As an outlook, up-to-date nanosafety issues are discussed. PMID:28362331

Review on the Processing and Properties of Polymer Nanocomposites and Nanocoatings and Their Applications in the Packaging, Automotive and Solar Energy Fields.

PubMed

Müller, Kerstin; Bugnicourt, Elodie; Latorre, Marcos; Jorda, Maria; Echegoyen Sanz, Yolanda; Lagaron, José M; Miesbauer, Oliver; Bianchin, Alvise; Hankin, Steve; Bölz, Uwe; Pérez, Germán; Jesdinszki, Marius; Lindner, Martina; Scheuerer, Zuzana; Castelló, Sara; Schmid, Markus

2017-03-31

For the last decades, nanocomposites materials have been widely studied in the scientific literature as they provide substantial properties enhancements, even at low nanoparticles content. Their performance depends on a number of parameters but the nanoparticles dispersion and distribution state remains the key challenge in order to obtain the full nanocomposites' potential in terms of, e.g., flame retardance, mechanical, barrier and thermal properties, etc., that would allow extending their use in the industry. While the amount of existing research and indeed review papers regarding the formulation of nanocomposites is already significant, after listing the most common applications, this review focuses more in-depth on the properties and materials of relevance in three target sectors: packaging, solar energy and automotive. In terms of advances in the processing of nanocomposites, this review discusses various enhancement technologies such as the use of ultrasounds for in-process nanoparticles dispersion. In the case of nanocoatings, it describes the different conventionally used processes as well as nanoparticles deposition by electro-hydrodynamic processing. All in all, this review gives the basics both in terms of composition and of processing aspects to reach optimal properties for using nanocomposites in the selected applications. As an outlook, up-to-date nanosafety issues are discussed.

Evaluation of an in situ chemically crosslinked hydrogel as a long-term vitreous substitute material.

PubMed

Tao, Yong; Tong, Xinming; Zhang, Yan; Lai, Jingjing; Huang, Yanbin; Jiang, Yan-Rong; Guo, Bao-Hua

2013-02-01

Currently there is no material that can be used as a long-term vitreous substitute, and this remains an unmet clinical need in ophthalmology. In this study, we developed an injectable, in situ chemically crosslinked hydrogel system and evaluated it in a rabbit model. The system consisted of two components, both based on multi-functional poly(ethylene glycol) (PEG) but with complementarily reactive end groups of thiol and active vinyl groups, respectively. The two components are mixed and injected as a solution mixture, react in vivo via the Michael addition route and form a chemically crosslinked hydrogel in situ. The linkages between the end groups and the backbone PEG chains are specially designed to ensure that the final network structure is hydrolysis-resistant. In the rabbit study and with an optimized operation protocol, we demonstrated that the hydrogel indeed formed in situ after injection, and remained transparent and stable during the study period of 9 months without significant adverse reactions. In addition, the hydrogel formed in situ showed rheological properties very similar to the natural vitreous. Therefore, our study demonstrated that this in situ chemically crosslinked PEG gel system is suitable as a potential long-term vitreous substitute. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Renal Angiomyolipoma: Mid- to Long-Term Results Following Embolization with Onyx

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

Thulasidasan, Narayanan, E-mail: narayanant@doctors.net.uk; Sriskandakumar, Srividhiya; Ilyas, Shahzad

PurposePercutaneous transcatheter embolization is currently the preferred treatment for ruptured or enlarging renal angiomyolipoma (AML), although the optimum choice of embolic material has not yet been established. We present mid- to long-term outcomes following embolization of AMLs with Onyx.Materials and MethodsTen AMLs in seven patients (including two with tuberous sclerosis) were embolized with Onyx. Patients were followed-up clinically, with tumour size and renal function measured pre- and post-procedure.ResultsMean pre-treatment AML size was 63.4 mm (range 42–100). Mean clinical follow-up was 431.4 days (range 153–986) and imaging follow-up 284.2 days (range 30–741). There was no haemorrhage from treated lesions within the follow-up period. Ofmore » patients who had cross-sectional imaging pre- and post-procedure, mean decrease in AML size of 22 mm was seen after Onyx embolization (p = 0.0058, 95 % CI 9.13–34.87). No significant difference between serum creatinine was seen pre- and post-procedure (p = 0.54, 95 % CI 8.63–4.85).ConclusionsOnyx embolization of renal AMLs is effective in the medium to long term, with theoretical benefits in safety and durability of result.« less

Performance study of galactic cosmic ray shield materials

NASA Technical Reports Server (NTRS)

Kim, Myung-Hee Y.; Wilson, John W.; Thibeault, Sheila A.; Nealy, John E.; Badavi, Francis F.; Kiefer, Richard L.

1994-01-01

The space program is faced with two difficult radiation protection issues for future long-term operations. First, retrofit of shield material or conservatism in shield design is prohibitively expensive and often impossible. Second, shielding from the cosmic heavy ions is faced with limited knowledge on the physical properties and biological responses of these radiations. The current status of space shielding technology and its impact on radiation health is discussed herein in terms of conventional protection practice and a test biological response model. The impact of biological response on the selection of optimum materials for cosmic ray shielding is presented in terms of the transmission characteristics of the shield material. Although the systematics of nuclear cross sections are able to demonstrate the relation of exposure risk to shield-material composition, the current uncertainty in-nuclear cross sections will not allow an accurate evaluation of risk reduction. This paper presents a theoretical study of risk-related factors and a pilot experiment to study the effectiveness of choice of shield materials to reduce the risk in space operations.

10 CFR 40.28 - General license for custody and long-term care of uranium or thorium byproduct materials disposal...

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 1 2011-01-01 2011-01-01 false General license for custody and long-term care of uranium... long-term care of uranium or thorium byproduct materials disposal sites. (a) A general license is... in this part for uranium or thorium mill tailings sites closed under title II of the Uranium Mill...

10 CFR 40.28 - General license for custody and long-term care of uranium or thorium byproduct materials disposal...

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 1 2012-01-01 2012-01-01 false General license for custody and long-term care of uranium... long-term care of uranium or thorium byproduct materials disposal sites. (a) A general license is... in this part for uranium or thorium mill tailings sites closed under title II of the Uranium Mill...

10 CFR 40.28 - General license for custody and long-term care of uranium or thorium byproduct materials disposal...

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 1 2013-01-01 2013-01-01 false General license for custody and long-term care of uranium... long-term care of uranium or thorium byproduct materials disposal sites. (a) A general license is... in this part for uranium or thorium mill tailings sites closed under title II of the Uranium Mill...

10 CFR 40.28 - General license for custody and long-term care of uranium or thorium byproduct materials disposal...

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 1 2014-01-01 2014-01-01 false General license for custody and long-term care of uranium... long-term care of uranium or thorium byproduct materials disposal sites. (a) A general license is... in this part for uranium or thorium mill tailings sites closed under title II of the Uranium Mill...

I Want More and Better Cells! - An Outreach Project about Stem Cells and Its Impact on the General Population.

PubMed

Varela Amaral, Sara; Forte, Teresa; Ramalho-Santos, João; Girão da Cruz, M Teresa

2015-01-01

Although science and technology impact every aspect of modern societies, there is still an extensive gap between science and society, which impairs the full exercise of citizenship. In the particular case of biomedical research increased investment should be accompanied by parallel efforts in terms of public information and engagement. We have carried out a project involving the production and evaluation of educational contents focused on stem cells - illustrated newspaper chronicles, radio interviews, a comic book, and animated videos - and monitored their impact on the Portuguese population. The study of the outreach materials in a heterogeneous sample of the population suggests that they are valuable tools to disseminate scientific messages, and that this is especially true for the comic-book format. Furthermore, the data showed that clear and stimulating outreach materials, that are able to teach new concepts and to promote critical thinking, increase engagement in science at different levels, depending on the depth of the concepts involved. Additionally, these materials can influence political, social and personal attitudes toward science. These results, together with the importance attributed to scientific research in stem cells by the population sampled, validates the diffusion of such materials as a significant contribution towards an overall public understanding and engagement in contemporary science, and this strategy should thus be considered in future projects. Regardless, stringent quality control must be implemented in order to efficiently communicate accurate scientific developments, and the public stimulated in terms of finding additional sources of reliable information.

Integrated evaluation of the performance of a more than seven year old permeable reactive barrier at a site contaminated with chlorinated aliphatic hydrocarbons (CAHs)

NASA Astrophysics Data System (ADS)

Muchitsch, Nanna; Van Nooten, Thomas; Bastiaens, Leen; Kjeldsen, Peter

2011-11-01

An important issue of concern for permeable reactive iron barriers is the long-term efficiency of the barriers due to the long operational periods required. Mineral precipitation resulting from the anaerobic corrosion of the iron filings and bacteria present in the barrier may play an important role in the long-term performance. An integrated study was performed on the Vapokon permeable reactive barrier (PRB) in Denmark by groundwater and iron core sample characterization. The detailed field groundwater sampling carried out from more than 75 well screens up and downstream the barrier showed a very efficient removal (> 99%) for the most important CAHs (PCE, TCE and 1,1,1-TCA). However, significant formation of cis-DCE within the PRB resulted in an overall insufficient efficiency for cis-DCE removal. The detailed analysis of the upstream groundwater revealed a very heterogeneous spatial distribution of contaminant loading into the PRB, which resulted in that only about a quarter of the barrier system is treating significant loads of CAHs. Laboratory batch experiments using contaminated groundwater from the site and iron material from the core samples revealed that the aged iron material performed equally well as virgin granular iron of the same type based on determined degradation rates despite that parts of the cored iron material were covered by mineral precipitates (especially iron sulfides, carbonate green rust and aragonite). The PCR analysis performed on the iron core samples indicated the presence of a microbial consortium in the barrier. A wide range of species were identified including sulfate and iron reducing bacteria, together with Dehalococcoides and Desulfuromonas species indicating microbial reductive dehalogenation potential. The microbes had a profound effect on the performance of the barrier, as indicated by significant degradation of dichloromethane (which is typically unaffected by zero valent iron) within the barrier.

Investigating the Language of Engineering Education

NASA Astrophysics Data System (ADS)

Variawa, Chirag

A significant part of professional communication development in engineering is the ability to learn and understand technical vocabulary. Mastering such vocabulary is often a desired learning outcome of engineering education. In promoting this goal, this research investigates the development of a tool that creates wordlists of characteristic discipline-specific vocabulary for a given course. These wordlists explicitly highlight requisite vocabulary learning and, when used as a teaching aid, can promote greater accessibility in the learning environment. Literature, including work in higher education, diversity and language learning, suggest that designing accessible learning environments can increase the quality of instruction and learning for all students. Studying the student/instructor interface using the framework of Universal Instructional Design identified vocabulary learning as an invisible barrier in engineering education. A preliminary investigation of this barrier suggested that students have difficulty assessing their understanding of technical vocabulary. Subsequently, computing word frequency on engineering course material was investigated as an approach for characterizing this barrier. However, it was concluded that a more nuanced method was necessary. This research program was built on previous work in the fields of linguistics and computer science, and lead to the design of an algorithm. The developed algorithm is based on a statistical technique called, Term Frequency-Inverse Document Frequency. Comparator sets of documents are used to hierarchically identify characteristic terms on a target document, such as course materials from a previous term of study. The approach draws on a standardized artifact of the engineering learning environment as its dataset; a repository of 2254 engineering final exams from the University of Toronto, to process the target material. After producing wordlists for ten courses, with the goal of highlighting characteristic discipline-specific terms, the effectiveness of the approach was evaluated by comparing the computed results to the judgment of subject-matter experts. The overall data show a good correlation between the program and the subject-matter experts. The results indicated a balance between accuracy and feasibility, and suggested that this approach could mimic subject-matter expertise to create a list discipline-specific vocabulary from course materials.

Properties of concrete containing different type of waste materials as aggregate replacement exposed to elevated temperature – A review

NASA Astrophysics Data System (ADS)

Ghadzali, N. S.; Ibrahim, M. H. W.; Sani, M. S. H. Mohd; Jamaludin, N.; Desa, M. S. M.; Misri, Z.

2018-04-01

Concrete is the chief material of construction and it is non-combustible in nature. However, the exposure to the high temperature such as fire can lead to change in the concrete properties. Due to the higher temperature, several changes in terms of mechanical properties were observed in concrete such as compressive strength, modulus of elasticity, tensile strength and durability of concrete will decrease significantly at high temperature. The exceptional fire-proof achievement of concrete is might be due to the constituent materials of concrete such as its aggregates. The extensive use of aggregate in concrete will leads to depletion of natural resources. Hence, the use of waste and other recycled and by-product material as aggregates replacements becomes a leading research. This review has been made on the utilization of waste materials in concrete and critically evaluates its effects on the concrete performances during the fire exposure. Therefore, the objective of this paper is to review the previous search work regarding the concrete containing waste material as aggregates replacement when exposed to elevated temperature and come up with different design recommendations to improve the fire resistance of structures.

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

Michael, Stephan; Chow, Weng; Schneider, Hans

In the framework of a microscopic model for intersubband gain from electrically pumped quantum-dot structures we investigate electrically pumped quantum-dots as active material for a mid-infrared quantum cascade laser. Our previous calculations have indicated that these structures could operate with reduced threshold current densities while also achieving a modal gain comparable to that of quantum well active materials. We study the influence of two important quantum-dot material parameters, here, namely inhomogeneous broadening and quantum-dot sheet density, on the performance of a proposed quantum cascade laser design. In terms of achieving a positive modal net gain, a high quantum-dot density canmore » compensate for moderately high inhomogeneous broadening, but at a cost of increased threshold current density. By minimizing quantum-dot density with presently achievable inhomogeneous broadening and total losses, significantly lower threshold densities than those reported in quantum-well quantum-cascade lasers are predicted by our theory.« less

Learning atoms for materials discovery.

PubMed

Zhou, Quan; Tang, Peizhe; Liu, Shenxiu; Pan, Jinbo; Yan, Qimin; Zhang, Shou-Cheng

2018-06-26

Exciting advances have been made in artificial intelligence (AI) during recent decades. Among them, applications of machine learning (ML) and deep learning techniques brought human-competitive performances in various tasks of fields, including image recognition, speech recognition, and natural language understanding. Even in Go, the ancient game of profound complexity, the AI player has already beat human world champions convincingly with and without learning from the human. In this work, we show that our unsupervised machines (Atom2Vec) can learn the basic properties of atoms by themselves from the extensive database of known compounds and materials. These learned properties are represented in terms of high-dimensional vectors, and clustering of atoms in vector space classifies them into meaningful groups consistent with human knowledge. We use the atom vectors as basic input units for neural networks and other ML models designed and trained to predict materials properties, which demonstrate significant accuracy. Copyright © 2018 the Author(s). Published by PNAS.

Quantized circular photogalvanic effect in Weyl semimetals

NASA Astrophysics Data System (ADS)

de Juan, Fernando; Grushin, Adolfo G.; Morimoto, Takahiro; Moore, Joel E.

The circular photogalvanic effect (CPGE) is the part of a photocurrent that switches depending on the sense of circular polarization of the incident light. It has been consistently observed in systems without inversion symmetry and depends on non-universal material details. We find that in a class of Weyl semimetals (e.g. SrSi2) and three-dimensional Rashba materials (e.g. doped Te) without inversion and mirror symmetries, the CPGE trace is effectively Quantized in terms of the combination of fundamental constants e3/h2 cɛ0 with no material-dependent parameters. This is so because the CPGE directly measures the topological charge of Weyl points near the Fermi surface, and non-quantized corrections from disorder and additional bands can be small over a significant range of incident frequencies. Moreover, the magnitude of the CPGE induced by a Weyl node is relatively large, which enables the direct detection of the monopole charge with current techniques.

Quantized circular photogalvanic effect in Weyl semimetals

NASA Astrophysics Data System (ADS)

de Juan, Fernando; Grushin, Adolfo G.; Morimoto, Takahiro; Moore, Joel E.

2017-07-01

The circular photogalvanic effect (CPGE) is the part of a photocurrent that switches depending on the sense of circular polarization of the incident light. It has been consistently observed in systems without inversion symmetry and depends on non-universal material details. Here we find that in a class of Weyl semimetals (for example, SrSi2) and three-dimensional Rashba materials (for example, doped Te) without inversion and mirror symmetries, the injection contribution to the CPGE trace is effectively quantized in terms of the fundamental constants e, h, c and with no material-dependent parameters. This is so because the CPGE directly measures the topological charge of Weyl points, and non-quantized corrections from disorder and additional bands can be small over a significant range of incident frequencies. Moreover, the magnitude of the CPGE induced by a Weyl node is relatively large, which enables the direct detection of the monopole charge with current techniques.

Elasticity Solution of an Adhesively Bonded Cover Plate of Various Geometries

NASA Technical Reports Server (NTRS)

Aksel, G. N.; Erdogan, F.

1985-01-01

The plane strain of adhesively bonded structures consisting of two different isotropic adherends is considered. By expressing the x-y components of the displacements in terms of Fourier integrals and using the corresponding boundary and continuity conditions, the integral equations for the general problem are obtained and solved numerically by applying Gauss-Chebyshev integration scheme. The shear and the normal stresses in the adhesive are calculated for various geometries and material properties for a stiffened plate under uniaxial tension. Numerical results involving the stress intensity factors and the strain energy release rate are presented. The closed-form expressions for the Fredholm kernels are provided to obtain the solution for an arbitrary geometry and material properties. For the general geometry, the contribution of the normal stress is quite significant, while for symmetric geometries, the shear stress is dominant, the normal stress vanishes if the adherends are of the same material and the same thickness.

Aspects of the mechanisms of smoke generation by burning materials

NASA Technical Reports Server (NTRS)

Bankston, C. P.; Zinn, B. T.; Browner, R. F.; Powell, E. A.

1981-01-01

An investigation of smoke generation during the burning of natural and synthetic solid materials (relevant to fire safety problems), under simulated fire conditions, is presented. Smoke formation mechanisms, including flaming and nonflaming combustion, are reviewed, and the complex physical, chemical, and electrical processes, important in smoke particulate production, are identified. With reference to the smoke formation mechanisms, measured experimental data are discussed, and include effects of ventilation gas temperature, dependence on material composition, and chemical analysis of smoke particulates. Significant differences in smoke characteristics are observed between flaming and nonflaming conditions, which is attributed to specific differences in controlling mechanisms and resultant ways leading to particulate formation. The effects of polymer substrate properties and effects of additives for a given substrate on smoke properties are also discussed in terms of basic processes. It is shown that many of the measured trends can be interpreted by considering postulated mechanisms of particulate formation.

Underexplored Opportunities for Natural Products in Drug Discovery.

PubMed

DeCorte, Bart L

2016-10-27

The importance of natural products in the treatment of human disease is well documented. While natural products continue to have a profound impact on human health, chemists have succeeded in generating semisynthetic analogues that sometimes overshadow the original natural product in terms of clinical significance. Synthetic efforts based on natural products have primarily focused on improving their drug-like features while targeting utility in the same biological space. A less documented phenomenon is that natural products can serve as powerful starting materials to generate drug substances with novel therapeutic utility that is unrelated to the biological space of the natural product starting material. In this Perspective, examples of natural product derived marketed drugs with therapeutic utility in clinical space that is different from the biological profile of the starting material are presented, demonstrating that this is not merely a theoretical concept but both a clinical reality and an underexplored opportunity.

Chapter 10.2: Encapsulant Materials for PV Modules

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

Kempe, Michael D

2017-01-07

Encapsulant materials used in photovoltaic (PV) modules serve multiple purposes; it provides optical coupling of PV cells and protection against environmental stress. Polymers must perform these functions under prolonged periods of high temperature, humidity, and UV radiation. When PV panels were first developed in the 1960s and the 1970s, the dominant encapsulants were based on polydimethyl siloxane (PDMS). Ethylene-co-vinyl acetate (EVA) is currently the dominant encapsulant chosen for PV applications, not because it has the best combination of properties, but because it is an economical option with an established history of acceptable durability. Getting new products onto the market ismore » challenging because there is no room for dramatic improvements, and one must balance the initial cost and performance with the unknowns of long-term service life. Recently, there has been renewed interest in using alternative encapsulant materials with some significant manufacturers switching from EVA to polyolefin elastomer-based (POE) alternatives.« less

Listening to a patient: An exploratory experimental investigation into the effects of vocalization and therapist gender on interpreting clinical material.

PubMed

Dauphin, Barry; Halverson, Stacey; Pouliot, Sarah; Slowik, Linda

2018-01-01

Carefully listening to the patient is of paramount importance for psychoanalysis and psychoanalytic psychotherapy. The present study explored whether patient vocalization as well as the gender of the analyst play significant roles in clinical listening. Fifty-one psychoanalysts and psychoanalytic therapists were randomly assigned to listen to one of two dramatized psychoanalytic sessions. The content of the sessions was the same for both versions, but the sessions were dramatized differently. Some differences emerged between the versions, especially on ratings of reality testing, impulse control, pressured speech, patient was confusing, and awareness of imagery. Furthermore, differences emerged between male and female analysts in terms of ratings of intervention strategies and countertransference reactions to the patient material. Session version and gender affect different ratings. Implications of the findings are discussed as is the utility of using more ecologically valid material in conducting empirical research into clinical judgment.

Outstanding Li-storage performance of LiFePO4@MWCNTs cathode material with 3D network structure for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Sun, Xiaodong; Zhang, Le

2018-05-01

In this work, the MWCNTs-decorated LiFePO4 microspheres (LiFePO4@MWCNTs) with a 3D network structure have been synthesized by a facile and efficient spray-drying approach followed by solid-state reaction in a reduction atmosphere. In the as-prepared composite, the MWCNTs around LiFePO4 nanoparticles can provide 3D conductive networks which greatly facilitate the transport of Li+-ion and electron during the electrochemical reaction. Compared to the pure LiFePO4 material, the LiFePO4@MWCNTs composite as cathode for lithium-ion batteries exhibits significantly improved Li-storage performance in terms of rate capability and cyclic stability. Therefore, we can speculate that the spray-drying approach is a promising route to prepare the high-performance electrode materials with 3D network structure for electrochemical energy storage.

Negative magnetoresistance of ultra-narrow superconducting nanowires in the resistive state

NASA Astrophysics Data System (ADS)

Arutyunov, K. Yu.

2008-02-01

We present a phenomenological model that qualitatively explains negative magnetoresistance in quasi-one-dimensional superconducting channels in the resistive state. The model is based on the assumption that fluctuations of the order parameter (phase slips) are responsible for the finite effective resistance of a narrow superconducting wire sufficiently close to the critical temperature. Each fluctuation is accompanied by an instantaneous formation of a quasi-normal region, of the order of the non-equilibrium quasiparticle relaxation length, ‘pinned’ to the core of the phase slip. The effective time-averaged voltage measured in experiments is a sum of two terms. The first is the conventional contribution associated with the rate of the fluctuations via the Josephson relation. The second term is the Ohmic contribution of this quasi-normal region. Depending on the material properties of the wire, there might be a range of magnetic fields where the first term is not significantly affected, while the second term is effectively suppressed, contributing to the experimentally observed negative magnetoresistance.

Genetics instruction with history of science: Nature of science learning

NASA Astrophysics Data System (ADS)

Kim, Sun Young

2007-12-01

This study explored the effect of history of genetics in teaching genetics and learning the nature of science (NOS). A quasi-experimental control group research design with pretests, posttests, and delayed posttests was used, combining qualitative data and quantitative data. Two classes which consisted of tenth grade biology students participated in this study. The present study involved two instructional interventions, Best Practice Instruction with History of Genetics (BPIw/HG) and Best Practice Instruction (BPI). The experimental group received BPIw/HG utilizing various historical materials from the history of genetics, while the control group was not introduced to historical materials. Scientific Attitude Inventory II, Genetics Terms' Definitions with Concept Mapping (GTDCM), NOS Terms' Definitions with Concept Mapping (NTDCM), and View of Nature of Science (VNOS-C) were used to investigate students' scientific attitude inventory, and their understanding of genetics as well as the NOS. The results showed that students' scientific attitude inventory, and their understanding of genetics and the NOS were not statistically significantly different in the pretest (p>.05). After the intervention, the experimental group of students who received BPIw/HG demonstrated better understanding of the NOS. NTDCM results showed that the experimental group was better in defining the NOS terms and constructing a concept map ( p<.01). In addition, the experimental group retained their understanding of the NOS two-months after the completion of the intervention, showing no statistically significant difference between the posttest and the delayed posttest of NTDCM (p>.05). Further, VNOS-C data indicated that a greater percentage of the experimental group than the control group improved their understanding of the NOS. However, the two groups' understanding of genetics concepts did not show any statistically significant difference in the pretest, the posttest, and the delayed posttest (p>.05). This result implicated that allocating classroom time in introducing history of science neither helped nor hindered learning science content.

Sealants in dentistry: a systematic review of the literature.

PubMed

Condò, R; Cioffi, A; Riccio, A; Totino, M; Condò, S G; Cerroni, L

2013-03-01

The occlusal surface is the most affected area by dental caries and the sealing of the pits and of the fissures has been found, in time, the preventive method most effective trying to counteract the onset. Currently, the WHO considers it as a primary preventive measure, in other words one of the most effective and least invasive available to ensure the complete protection and the total preservation of the occlusal carious by the phenomenon. THE AIM OF THIS WORK HAS BEEN TO PERFORM A SYSTEMATIC REVIEW OF THE LITERATURE ON CLINICAL TRIALS OF DIFFERENT SEALING MATERIALS, IN ORDER TO: compare their individual characteristics, highlight the reliability and the long-term efficacy and identify the most significant variables, both technological and clinics, in order to declare whether or not the success of this method prior. The research has been carried out in the MEDLINE database by choosing keywords as "sealants" and "follow up". Only studies published in the last thirteen years have been considered and have been evaluated only types of scientific articles that fall within the definition of Anglo-Saxon "Clinical Trial" and "Controlled Clinical Trial", excluding all experimental works in vitro, case-reports, meta-analyzes and literature reviews. Have been also considered only scientific papers on patients between the ages of 0 and 18 years. Out of 29 studies, evaluating a total of 2900 individuals (aged between 2.5 and 17 years), 7411 seals made by using resin-based sealants (RB Sealants), modified glass ionomer sealants (RMGI) and compomer sealants have been analyzed. The best retention capacity of the material in time has been obtained from the use of RB Sealants compared to RMGI, demonstrating retention values much lower with partial loss of material at a distance of one year from the clinic. The compomers demonstrate retention values intermediates. The incidence of caries in a year is negligible for all sealants application. In terms of retention, resin-based sealants (RB Sealants) are the materials that give more guarantees of success at 12 months, while in the same period there haven't been significant differences in caries prevention of disease among the various classes sealing materials analyzed.

Towards increased recycling of household waste: Documenting cascading effects and material efficiency of commingled recyclables and biowaste collection.

PubMed

Cimpan, Ciprian; Rothmann, Marianne; Hamelin, Lorie; Wenzel, Henrik

2015-07-01

Municipal solid waste (MSW) management remains a challenge, even in Europe where several countries now possess capacity to treat all arising MSW, while others still rely on unsustainable disposal pathways. In the former, strategies to reach higher recycling levels are affecting existing waste-to-energy (WtE) treatment infrastructure, by inducing additional overcapacity and this in turn rebounds as pressure on the waste and recyclable materials markets. This study addresses such situations by documenting the effects, in terms of resource recovery, global warming potential (GWP) and cumulative energy demand (CED), of a transition from a self-sufficient waste management system based on minimal separate collection and efficient WtE, towards a system with extended separate collection of recyclable materials and biowaste. In doing so, it tackles key questions: (1) whether recycling and biological treatment are environmentally better compared to highly efficient WtE, and (2) what are the implications of overcapacity-related cascading effects, namely waste import, when included in the comparison of alternative waste management systems. System changes, such as the implementation of kerbside separate collection of recyclable materials were found to significantly increase material recovery, besides leading to substantial GWP and CED savings in comparison to the WtE-based system. Bio-waste separate collection contributed with additional savings when co-digested with manure, and even more significantly when considering future renewable energy background systems reflecting the benefits induced by the flexible use of biogas. Given the current liberalization of trade in combustible waste in Europe, waste landfilling was identified as a short-to-medium-term European-wide waste management marginal reacting to overcapacity effects induced by the implementation of increased recycling strategies. When waste import and, consequently, avoided landfilling were included in the system boundary, additional savings of up to 700 kg CO2 eq. and 16 GJ eq. of primary energy per tonne of imported waste were established. Conditions, such as energy recovery efficiency, and thresholds beyond which import-related savings potentially turn into GWP burdens were also determined. Copyright © 2015 Elsevier Ltd. All rights reserved.

Stabilization of metal(loid)s in two contaminated agricultural soils: Comparing biochar to its non-pyrolysed source material.

PubMed

Trakal, Lukáš; Raya-Moreno, Irene; Mitchell, Kerry; Beesley, Luke

2017-08-01

Two metal(loid) contaminated agricultural soils were amended with grape stalk (wine production by-product)-derived biochar as well as its pre-pyrolysed origin material, to investigate their geochemical impacts on As, Cr, Cu and Zn. Detailed physico-chemical evaluation combined with a column leaching test determined the retention of metal(loid)s from soil solution by each amendments. A pot experiment measured metal(loid)s in soil pore water and their uptake to ryegrass when the amendments were mixed into soils at 1 and 5% (w/w). Total Cr and Zn concentrations were reduced furthest in column leachates by the addition of raw material and biochar respectively, compared to the untreated soil; Cr(III) was the predominant specie initially due to rapid acidification of leachates and organic complexation resulting from raw material addition. Loadings of metal(loid)s to the amendments recovered from the post-leached columns were in the order Cu » Zn > Cr ≈ As. In the pot test ryegrass Cr uptake was initiated by the addition of both amendments, compared to the untreated soil, whereas only biochar addition resulted in significant increases in Zn uptake, explained by its significant enhancement of ryegrass biomass yield, especially at 5% dosage; raw material addition significantly decreased biomass yields. Inconsistent relationships between pore water parameters and ryegrass uptake were common to both soils investigated. Therefore, whilst both amendments modified soil metal(loid) geochemistry, their effects differed fundamentally; in environmental risk management terms these results highlight the need to investigate the detailed geochemical response of contaminated soils to diverse organic amendment additions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of different packing materials for the biofiltration of air toxics.

PubMed

Sakuma, Takeyuki; Hattori, Toshihiro; Deshusses, Marc A

2006-11-01

Four different biofilter packing materials (two porous ceramics, perlite, and open pore polyurethane foam) were compared for the removal of toluene vapors. The focus was on evaluating performance at relatively short gas retention time (13.5 and 27 sec). The reactors were initially operated as biotrickling filters with continuous feeding and trickling of a nutrient solution. After significant plugging of the biotrickling filter beds with biomass was observed, the operation mode was switched to biofiltration with only periodic supply of mineral nutrients. This resulted in stable conditions, which allowed detailed investigations over > 6 months. The reactor packed with cattle bone Porcelite (CBP), a ceramic material containing some macronutrients and micronutrients, exhibited the highest performance. The critical load (i.e., load at which 95% removal occurred) was 29 g m(-3) hr(-1) at a gas retention time of 13.5 sec and 66 g m(-3) hr(-1) at a gas retention time of 27 sec. After the long-term experiment, the packing materials were taken from the reactors and examined. The reactors were divided into three sections, top, middle, and bottom, to determine whether spatial differentiation of biomass occurred. The assays included a double-staining technique to count total and live microorganisms and determination of moisture, protein, and dry weight contents. Microbial community analysis was also conducted by denaturing gradient gel electrophoresis. The results showed that most reactors had a significant fraction of inactive biomass. Comparatively, the CBP biofilter held significantly higher densities of active biomass, which may be the reason for the higher toluene removal performance. The analyses suggest that favorable material properties and the nutrients slowly released by the CBP provided better environmental conditions for the process culture.

Fracture resistance of implant- supported monolithic crowns cemented to zirconia hybrid-abutments: zirconia-based crowns vs. lithium disilicate crowns

PubMed Central

Nawafleh, Noor; Öchsner, Andreas; George, Roy

2018-01-01

PURPOSE The aim of this in vitro study was to investigate the fracture resistance under chewing simulation of implant-supported posterior restorations (crowns cemented to hybrid-abutments) made of different all-ceramic materials. MATERIALS AND METHODS Monolithic zirconia (MZr) and monolithic lithium disilicate (MLD) crowns for mandibular first molar were fabricated using computer-aided design/computer-aided manufacturing technology and then cemented to zirconia hybrid-abutments (Ti-based). Each group was divided into two subgroups (n=10): (A) control group, crowns were subjected to single load to fracture; (B) test group, crowns underwent chewing simulation using multiple loads for 1.2 million cycles at 1.2 Hz with simultaneous thermocycling between 5℃ and 55℃. Data was statistically analyzed with one-way ANOVA and a Post-Hoc test. RESULTS All tested crowns survived chewing simulation resulting in 100% survival rate. However, wear facets were observed on all the crowns at the occlusal contact point. Fracture load of monolithic lithium disilicate crowns was statistically significantly lower than that of monolithic zirconia crowns. Also, fracture load was significantly reduced in both of the all-ceramic materials after exposure to chewing simulation and thermocycling. Crowns of all test groups exhibited cohesive fracture within the monolithic crown structure only, and no abutment fractures or screw loosening were observed. CONCLUSION When supported by implants, monolithic zirconia restorations cemented to hybrid abutments withstand masticatory forces. Also, fatigue loading accompanied by simultaneous thermocycling significantly reduces the strength of both of the all-ceramic materials. Moreover, further research is needed to define potentials, limits, and long-term serviceability of the materials and hybrid abutments. PMID:29503716

Exceptional oxygen reduction reaction activity and durability of platinum–nickel nanowires through synthesis and post-treatment optimization

DOE PAGES

Alia, Shaun M.; Ngo, Chilan; Shulda, Sarah; ...

2017-04-11

For the first time, extended nanostructured catalysts are demonstrated with both high specific activity (>6000 μA cm Pt –2 at 0.9 V) and high surface areas (>90 m 2 g Pt –1). Platinum–nickel (Pt—Ni) nanowires, synthesized by galvanic displacement, have previously produced surface areas in excess of 90 m 2 g Pt –1, a significant breakthrough in and of itself for extended surface catalysts. Unfortunately, these materials were limited in terms of their specific activity and durability upon exposure to relevant electrochemical test conditions. Through a series of optimized postsynthesis steps, significant improvements were made to the activity (3-fold increasemore » in specific activity), durability (21% mass activity loss reduced to 3%), and Ni leaching (reduced from 7 to 0.3%) of the Pt—Ni nanowires. Finally, these materials show more than a 10-fold improvement in mass activity compared to that of traditional carbon-supported Pt nanoparticle catalysts and offer significant promise as a new class of electrocatalysts in fuel cell applications.« less

Exceptional oxygen reduction reaction activity and durability of platinum–nickel nanowires through synthesis and post-treatment optimization

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

Alia, Shaun M.; Ngo, Chilan; Shulda, Sarah

For the first time, extended nanostructured catalysts are demonstrated with both high specific activity (>6000 μA cm Pt –2 at 0.9 V) and high surface areas (>90 m 2 g Pt –1). Platinum–nickel (Pt—Ni) nanowires, synthesized by galvanic displacement, have previously produced surface areas in excess of 90 m 2 g Pt –1, a significant breakthrough in and of itself for extended surface catalysts. Unfortunately, these materials were limited in terms of their specific activity and durability upon exposure to relevant electrochemical test conditions. Through a series of optimized postsynthesis steps, significant improvements were made to the activity (3-fold increasemore » in specific activity), durability (21% mass activity loss reduced to 3%), and Ni leaching (reduced from 7 to 0.3%) of the Pt—Ni nanowires. Finally, these materials show more than a 10-fold improvement in mass activity compared to that of traditional carbon-supported Pt nanoparticle catalysts and offer significant promise as a new class of electrocatalysts in fuel cell applications.« less

Optical properties of A Fe 2 As 2 ( A = Ca , Sr, and Ba) single crystals

DOE PAGES

Dai, Y. M.; Akrap, Ana; Bud'ko, S. L.; ...

2016-11-23

The detailed optical properties have been determined for the iron-based materials A Fe 2 As 2 , where A = Ca , Sr, and Ba, for light polarized in the iron-arsenic (a-b) planes over a wide frequency range, above and below the magnetic and structural transitions at T N = 138 , 195, and 172 K, respectively. The real and imaginary parts of the complex conductivity are fit simultaneously using two Drude terms in combination with a series of oscillators. Above T N, the free-carrier response consists of a weak, narrow Drude term, and a strong, broad Drude term, both of which show only a weak temperature dependence. Below T N there is a slight decrease of the plasma frequency but a dramatic drop in the scattering rate for the narrow Drude term, and for the broad Drude term there is a significant decrease in the plasma frequency, while the decrease in the scattering rate, albeit significant, is not as severe. The small values observed for the scattering rates for the narrow Drude term for Tmore » $$\\ll$$ T N may be related to the Dirac conelike dispersion of the electronic bands. Below T N new features emerge in the optical conductivity that are associated with the reconstruction Fermi surface and the gapping of bands at Δ 1 ≃ 45 – 80 meV, and Δ 2 ≃ 110 – 210 meV. In conclusion, the reduction in the spectral weight associated with the free carriers is captured by the gap structure; specifically, the spectral weight from the narrow Drude term appears to be transferred into the low-energy gap feature, while the missing weight from the broad term shifts to the high-energy gap.« less

The effect of communication change on long-term reductions in child exposure to conflict: impact of the promoting strong African American families (ProSAAF) program.

PubMed

Beach, Steven R H; Barton, Allen W; Lei, Man Kit; Brody, Gene H; Kogan, Steven M; Hurt, Tera R; Fincham, Frank D; Stanley, Scott M

2014-12-01

African American couples (n = 331) with children, 89% of whom were married, were assigned to either (a) a culturally sensitive couple- and parenting-enhancement program (ProSAAF) or (b) an information-only control condition in which couples received self-help materials. Husbands averaged 41 years of age and wives averaged 39 years. We found significant effects of program participation in the short term on couple communication, which was targeted by the intervention, as well as over the long term, on self-reported arguing in front of children. Long-term parenting outcomes were fully mediated by changes in communication for wives, but not for husbands. For husbands, positive change depended on amount of wife reported change. We conclude that wives' changes in communication from baseline to posttest may be more pivotal for the couples' long-term experience of decreased arguing in front of children than are husbands' changes, with wives' changes leading to changes in both partners' reports of arguments in front of children. © 2014 Family Process Institute.

“Terms and conditions of use” for journal articles and scholarly journals : A survey on the licensing processes associated with electronic scholarly materials

NASA Astrophysics Data System (ADS)

Hidaka, Masako

Copyright policies and terms directly affect the approach taken by journal editors, authors and readers regarding dealing with of articles and/or copyrighted materials. However Japanese academic society publishers have some trouble in licensing processes for copyrighted materials as previous studies pointed out. In 2011 we conducted a survey on “terms and conditions of use” of electronic journal and the licensing practices associated with electronic scholarly materials. The survey showed commercial publishers have enough announcements on reuse of copyrighted materials for readers. On the other hand Japanese academic societies' cares for readers tend to not enough. They publish journals both in Japanese and in English. Subsequently, English and Japanese templates of “terms and conditions of use” for Japanese academic society publishers were proposed. The templates were developed based on an understanding of the International Association of Scientific, Technical and Medical Publishers' “STM Permissions Guidelines,” which were designed to establish a standard and reasonable approach to granting permission for republication to all signatory publishers.The survey showed that Japanese academic society publishers and commercial publishers are facing the same issues regarding acceptable use of electronic supplemental materials for journal articles. This issue remains to be solved.

Paper recycling framework, the "Wheel of Fiber".

PubMed

Ervasti, Ilpo; Miranda, Ruben; Kauranen, Ilkka

2016-06-01

At present, there is no reliable method in use that unequivocally describes paper industry material flows and makes it possible to compare geographical regions with each other. A functioning paper industry Material Flow Account (MFA) that uses uniform terminology and standard definitions for terms and structures is necessary. Many of the presently used general level MFAs, which are called frameworks in this article, stress the importance of input and output flows but do not provide a uniform picture of material recycling. Paper industry is an example of a field in which recycling plays a key role. Additionally, terms related to paper industry recycling, such as collection rate, recycling rate, and utilization rate, are not defined uniformly across regions and time. Thus, reliably comparing material recycling activity between geographical regions or calculating any regional summaries is difficult or even impossible. The objective of this study is to give a partial solution to the problem of not having a reliable method in use that unequivocally describes paper industry material flows. This is done by introducing a new material flow framework for paper industry in which the flow and stage structure supports the use of uniform definitions for terms related to paper recycling. This new framework is termed the Detailed Wheel of Fiber. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rethinking liquid biopsy: Microfluidic assays for mobile tumor cells in human body fluids.

PubMed

Neoh, Kuang Hong; Hassan, Ayon Ahmed; Chen, Anqi; Sun, Yukun; Liu, Peng; Xu, Kai-Feng; Wong, Alice S T; Han, Ray P S

2018-01-01

Traditionally, liquid biopsy is a blood test involving the harvesting of tumor materials from peripheral blood. Tumor cells from non-blood body fluids have always been clinically available in cytological examinations but limited for use in differential diagnosis due to the low sensitivity of conventional cytopathology. With the recent significant progress in microfluidic and downstream molecular technologies, liquid biopsies have now evolved to include harvesting tumor cells and DNA fragments in all kinds of non-blood body fluids. This expansion into general body fluids presages the notion that liquid biopsy could soon be used in competition, as well as, in complementarity with tissue biopsy. Preliminary research of fluid-harvested tumor materials to spot early-stage tumors, monitor disease progression for metastasis and recurrence, and detect chemoresistance have been reported. To reflect the propagation of tumor cells in non-blood body fluids, we introduced the term Mobile Tumor Cells (MTCs), in lieu of the widely accepted term of circulating tumor cells (CTCs) resident in the bloodstream. Our review starts with a discussion on the clinical significance of MTCs, followed by a presentation of microfluidic techniques for MTC capture and various strategies for their identification. Hopefully, the phenotypic and genomic data acquired from harvested MTCs can be used to guide and improve cancer treatment decisions. Copyright © 2017 Elsevier Ltd. All rights reserved.

From the "metaphysics of the individual" to the critique of society: on the practical significance of Michel Henry's phenomenology of life.

PubMed

Staudigl, Michael

This essay explores the practical significance of Michel Henry's "material phenomenology." Commencing with an exposition of his most basic philosophical intuition, i.e., his insight that transcendental affectivity is the primordial mode of revelation of our selfhood, the essay then brings to light how this intuition also establishes our relation to both the world and others. Animated by a radical form of the phenomenological reduction, Henry's material phenomenology brackets the exterior world in a bid to reach the concrete interior transcendental experience at the base of all exteriority. The essay argues that this "counter reduction," designed as a practical orientation to the world, suspends all traditional parameters of onto(theo)logical individuation in order to rethink subjectivity in terms of its transcendental corporeality, i.e., in terms of the invisible display of "affective flesh." The development of this "metaphysics of the individual" anchors his "practical philosophy" as he developed it-under shifting accents-throughout his oeuvre. In particular, the essay brings into focus Henry's reflections on modernity, the industry of mass culture and their "barbaric" movements. The essay briefly puts these cultural and political areas of Henry's of thinking into contact with his late "theological turn," i.e., his Christological account of Life and the (inter)subjective self-realization to which it gives rise.

Tapping Resources in Municipal Solid Waste

ERIC Educational Resources Information Center

Blum, S. L.

1976-01-01

Municipal solid waste disposal is becoming complex as costs, wastes, and environmental restrictions increase. Recovery and recycling of materials presents problems of financing, ownership, and operation, technology, and marketing. Energy and materials recovery offers long-term economic and environmental incentives in terms of growing shortages and…

40 CFR 434.80 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... grubbing area means the area where woody plant materials that would interfere with soil salvage operations have been removed or incorporated into the soil that is being salvaged. (b) The term regraded area... means undissolved organic and inorganic material transported or deposited by water. (d) The term...

40 CFR 415.91 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... of any raw material, intermediate product, finished product, by-product, or waste product. The term... contact with any raw material, intermediate product, finished product, by-product or waste product by... this subpart. (b) The term product shall mean hydrogen peroxide as a one hundred percent hydrogen...

Test methods for environment-assisted cracking

NASA Astrophysics Data System (ADS)

Turnbull, A.

1992-03-01

The test methods for assessing environment assisted cracking of metals in aqueous solution are described. The advantages and disadvantages are examined and the interrelationship between results from different test methods is discussed. The source of differences in susceptibility to cracking occasionally observed from the varied mechanical test methods arises often from the variation between environmental parameters in the different test conditions and the lack of adequate specification, monitoring, and control of environmental variables. Time is also a significant factor when comparing results from short term tests with long exposure tests. In addition to these factors, the intrinsic difference in the important mechanical variables, such as strain rate, associated with the various mechanical tests methods can change the apparent sensitivity of the material to stress corrosion cracking. The increasing economic pressure for more accelerated testing is in conflict with the characteristic time dependence of corrosion processes. Unreliable results may be inevitable in some cases but improved understanding of mechanisms and the development of mechanistically based models of environment assisted cracking which incorporate the key mechanical, material, and environmental variables can provide the framework for a more realistic interpretation of short term data.

Efficient Gas-Sensing for Formaldehyde with 3D Hierarchical Co3O4 Derived from Co5-Based MOF Microcrystals.

PubMed

Zhou, Wei; Wu, Ya-Pan; Zhao, Jun; Dong, Wen-Wen; Qiao, Xiu-Qing; Hou, Dong-Fang; Bu, Xianhui; Li, Dong-Sheng

2017-11-20

Detecting formaldehyde at low operating temperature and maintaining long-term stability are of great significance. In this work, a hierarchical Co 3 O 4 nanostructure has been fabricated by calcining Co 5 -based metal-organic framework (MOF) microcrystals. Co 3 O 4 -350 particles were used for efficient gas-sensing for the detecting of formaldehyde vapor at lower working temperature (170 °C), low detection limit of 10 ppm, and long-term stability (30 days), which not only is the optimal value among all reported pure Co 3 O 4 sensing materials for the detection of formaldehyde but also is superior to that of majority of Co 3 O 4 -based composites. Such extraordinarily efficient properties might be resulted from hierarchically structures, larger surface area and unique pore structure. This strategy is further confirmed that MOFs, especially Co-clusters MOFs, could be used as precursor to synthesize 3D nanostructure metal oxide materials with high-performance, which possess high porosity and more active sites and shorter ionic diffusion lengths.

Radiation chemistry for modern nuclear energy development

NASA Astrophysics Data System (ADS)

Chmielewski, Andrzej G.; Szołucha, Monika M.

2016-07-01

Radiation chemistry plays a significant role in modern nuclear energy development. Pioneering research in nuclear science, for example the development of generation IV nuclear reactors, cannot be pursued without chemical solutions. Present issues related to light water reactors concern radiolysis of water in the primary circuit; long-term storage of spent nuclear fuel; radiation effects on cables and wire insulation, and on ion exchangers used for water purification; as well as the procedures of radioactive waste reprocessing and storage. Radiation effects on materials and enhanced corrosion are crucial in current (II/III/III+) and future (IV) generation reactors, and in waste management, deep geological disposal and spent fuel reprocessing. The new generation of reactors (III+ and IV) impose new challenges for radiation chemists due to their new conditions of operation and the usage of new types of coolant. In the case of the supercritical water-cooled reactor (SCWR), water chemistry control may be the key factor in preventing corrosion of reactor structural materials. This paper mainly focuses on radiation effects on long-term performance and safety in the development of nuclear power plants.

Simultaneous Thermal and Gamma Radiation Aging of Electrical Cable Polymers

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

Fifield, Leonard S.

The polymers used for insulation in nuclear power plant electrical cables are susceptible to aging during long term operation. Elevated temperature is the primary contributor to changes in polymer structure that result loss of mechanical and electrical properties, but gamma radiation is also a significant source of degradation for polymers used within relevant plant locations. Despite many years of polymer degradation research, the combined effects of simultaneous exposure to thermal and radiation stress are not well understood. As nuclear operators contemplate and prepare for extended operations beyond initial license periods, a predictive understanding of exposure-based cable material degradation is becomingmore » an increasingly important input to safety, licensing, operations and economic decisions. We are focusing on carefully-controlled simultaneous thermal and gamma radiation accelerating aging and characterization of the most common nuclear cable polymers to understand the relative contributions of temperature, time, dose and dose rate to changes in cable polymer material structure and properties. Improved understanding of cable performance in long term operation will help support continued sustainable nuclear power generation.« less

Kinetic Energy Corrections for Slip-Stick Behavior in Brittle Adhesives

NASA Technical Reports Server (NTRS)

Macon, David J.; Anderson, Greg L.; McCool, Alex (Technical Monitor)

2001-01-01

Fracture mechanics is the study of the failure of a body that contains a flaw. In the energy balance approach to fracture mechanics, contributions from the external work and elastic strain energy are accounted for but rarely are corrections for the kinetic energy given. Under slip-stick conditions, part of the external work is expended as kinetic energy. The magnitude of this kinetic energy depends upon the shape of the crack. A specimen with a blunt crack will fail at a high load and the crack will catastrophically travel through the material until the kinetic energy is dissipated. Material with a sharp crack will fail at a lower load but will still be catastrophic in nature. A kinetic term is incorporated into the energy balance approach. This term accounts for the velocity of the crack after failure and how far the crack travels before arresting. This correction makes the shape of the initiation crack irrelevant. When applied to data generated by tapered double cantilever beam specimens under slip-stick conditions, the scatter in the measured critical strain energy release rate is significantly reduced.

To have or to learn? The effects of materialism on British and Chinese children's learning.

PubMed

Ku, Lisbeth; Dittmar, Helga; Banerjee, Robin

2014-05-01

This article presents a systematic attempt to examine the associations of materialism with learning in 9- to 11-year-old children in 2 countries of similar economic development but different cultural heritage. Using cross-sectional, longitudinal, and experimental methods, we test a theoretically driven model of associations among materialism, learning motivations, and learning outcomes. Convergent findings suggest that a materialist orientation in elementary school children lowers intrinsic learning motivations, fosters extrinsic learning motivations, and leads to poorer learning outcomes. Materialism was linked directly to lower exam performance, and this link was mediated by lower mastery and heightened performance goals, with patterns not differing between British and Hong Kong Chinese children (Study 1). A follow-up showed that initial materialism predicted worse exam grades 1 year later, suggesting a detrimental long-term effect on Chinese children's school performance (Study 2). We then tested relationships between materialism and learning experimentally, by priming a momentary (state) orientation toward materialism. Writing about material possessions and money affected Chinese children's learning motivations, so that they endorsed lower mastery and higher performance goals (Study 3). A video-diary materialism prime had significant effects on actual learning behaviors, leading British children to (a) choose a performance-oriented learning task over a mastery-oriented task and (b) give up on the task more quickly (Study 4). This research has important implications for personality psychology, educational policy, and future research.

Guiding optimal biofuels :

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

Paap, Scott M.; West, Todd H.; Manley, Dawn Kataoka

2013-01-01

In the current study, processes to produce either ethanol or a representative fatty acid ethyl ester (FAEE) via the fermentation of sugars liberated from lignocellulosic materials pretreated in acid or alkaline environments are analyzed in terms of economic and environmental metrics. Simplified process models are introduced and employed to estimate process performance, and Monte Carlo analyses were carried out to identify key sources of uncertainty and variability. We find that the near-term performance of processes to produce FAEE is significantly worse than that of ethanol production processes for all metrics considered, primarily due to poor fermentation yields and higher electricitymore » demands for aerobic fermentation. In the longer term, the reduced cost and energy requirements of FAEE separation processes will be at least partially offset by inherent limitations in the relevant metabolic pathways that constrain the maximum yield potential of FAEE from biomass-derived sugars.« less

Spin-Wave Excitations Evidencing the Kitaev Interaction in Single Crystalline α -RuCl3

NASA Astrophysics Data System (ADS)

Ran, Kejing; Wang, Jinghui; Wang, Wei; Dong, Zhao-Yang; Ren, Xiao; Bao, Song; Li, Shichao; Ma, Zhen; Gan, Yuan; Zhang, Youtian; Park, J. T.; Deng, Guochu; Danilkin, S.; Yu, Shun-Li; Li, Jian-Xin; Wen, Jinsheng

2017-03-01

Kitaev interactions underlying a quantum spin liquid have long been sought, but experimental data from which their strengths can be determined directly, are still lacking. Here, by carrying out inelastic neutron scattering measurements on high-quality single crystals of α -RuCl3 , we observe spin-wave spectra with a gap of ˜2 meV around the M point of the two-dimensional Brillouin zone. We derive an effective-spin model in the strong-coupling limit based on energy bands obtained from first-principles calculations, and find that the anisotropic Kitaev interaction K term and the isotropic antiferromagnetic off-diagonal exchange interaction Γ term are significantly larger than the Heisenberg exchange coupling J term. Our experimental data can be well fit using an effective-spin model with K =-6.8 meV and Γ =9.5 meV . These results demonstrate explicitly that Kitaev physics is realized in real materials.

10 CFR 962.3 - Byproduct material.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Byproduct material. 962.3 Section 962.3 Energy DEPARTMENT OF ENERGY BYPRODUCT MATERIAL § 962.3 Byproduct material. (a) For purposes of this part, the term byproduct material means any radioactive material (except special nuclear material) yielded in or made...

10 CFR 962.3 - Byproduct material.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Byproduct material. 962.3 Section 962.3 Energy DEPARTMENT OF ENERGY BYPRODUCT MATERIAL § 962.3 Byproduct material. (a) For purposes of this part, the term byproduct material means any radioactive material (except special nuclear material) yielded in or made...

10 CFR 962.3 - Byproduct material.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Byproduct material. 962.3 Section 962.3 Energy DEPARTMENT OF ENERGY BYPRODUCT MATERIAL § 962.3 Byproduct material. (a) For purposes of this part, the term byproduct material means any radioactive material (except special nuclear material) yielded in or made...

10 CFR 962.3 - Byproduct material.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Byproduct material. 962.3 Section 962.3 Energy DEPARTMENT OF ENERGY BYPRODUCT MATERIAL § 962.3 Byproduct material. (a) For purposes of this part, the term byproduct material means any radioactive material (except special nuclear material) yielded in or made...

Inorganic materials for bone repair or replacement applications.

PubMed

Hertz, Audrey; Bruce, Ian J

2007-12-01

In recent years, excipient systems have been used increasingly in biomedicine in reconstructive and replacement surgery, as bone cements, drug-delivery vehicles and contrast agents. Particularly, interest has been growing in the development and application of controlled pore inorganic ceramic materials for use in bone-replacement and bone-repair roles and, in this context, attention has been focused on calcium-phosphate, bioactive glasses and SiO2- and TiO2-based materials. It has been shown that inorganic materials that most closely mimic bone structure and surface chemistry most closely function best in bone replacement/repair and, in particular, if a substance possesses a macroporous structure (pores and interconnections >100 microm diameter), then cell infiltration, bone growth and vascularization can all be promoted. The surface roughness and micro/mesoporosity of a material have also been observed to significantly influence its ability to promote apatite nucleation and cell attachment significantly. Pores (where present) can also be packed with pharmaceuticals and biomolecules (e.g., bone morphogenetic proteins [BMPs], which can stimulate bone formation). Finally, the most bio-efficient - in terms of collagen formation and apatite nucleation - materials are those that are able to provide soluble mineralizing species (Si, Ca, PO(4)) at their implant sites and/or are doped or have been surface-activated with specific functional groups. This article presents the context and latest advances in the field of bone-repair materials, especially with respect to the development of bioactive glasses and micro/mesoporous and macroporous inorganic scaffolds. It deals with the possible methods of preparing porous pure/doped or functionalized silicas or their composites, the studies that have been undertaken to evaluate their abilities to act as bone repair scaffolds and also presents future directions for work in that context.

Aggregative stability of fungicidal nanomodifier based on zinc hydrosilicates

NASA Astrophysics Data System (ADS)

Grishina, Anna; Korolev, Evgeniy

2018-03-01

Currently, there is a strong need of high performance multi functional materials in high-rise construction. Obviously, such materials should be characterized by high strength; but for interior rooms biosafety is important as well. The promising direction to obtain both high strength and maintain biosafety in buildings and structures is to manage the structure of mineral binders by means of fungicidal nanomodifier based on zinc hydrosilicates. In the present work the aggregative stability of colloidal solutions of zinc hydrosilicates after one year of storage was studied. It has been established that the concentration of iron (III) hydroxide used to prepare the precursor of zinc hydrosilicates has a significant effect on the long-term aggregative stability: as the concentration of iron (III) hydroxide increases, the resistance of the fungicidal nanomodifier increases. It was found that, despite the minimal concentration of nano-sized zinc hydrosilicates (0.028%), the colloidal solution possesses a low long-term aggregative stability; while in the initial period (not less than 14 days) the colloidal solution of the nanomodifier is aggregatively stable. It is shown that when the ratio in the colloidal solution of the amount of the substance CH3COOH / SiO2 = 0.43 is reached, an increase in the polymerization rate is observed, which is the main cause of low aggregative stability. Colloidal solutions containing zinc hydrosilicates synthesized at a concentration of iron (III) hydroxide used to produce a precursor equal to 0.7% have a long-term aggregative stability and do not significantly change the reduced particle. Such compositions are to be expediently used for the nanomodifying of building composites in order to control their structure formation and to create conditions that impede the development of various mycelial fungi.

Optical absorption in 3D topological insulator Bi2Te3 with applications to THz detectors (Presentation Recording)

NASA Astrophysics Data System (ADS)

Sengupta, Parijat; Bellotti, Enrico

2015-08-01

Topological insulators (TI) are a new class of materials that have an energy gap in bulk but possess gapless states bound to the sample surface or edge that have been theoretically predicted and experimentally observed [1]. The topological state in Bi2Te3 is characterized by a linear dispersion and a Dirac cone at the Γpoint. The optical absorption on the surface of a TI is given by the standard graphene-like απ/2 when a linear dispersion is assumed. Realistically, at k-points away from Γ, higher order cubic terms in k that represent the underlying hexagonal symmetry [2] of the crystal dominate and give rise to warping of bands. The optical absorption of a ferromagnetic coated gapped 3D TI film with warping terms considered is longer απ/2 but significantly modified. We demonstrate, by using wave functions from a continuum-Hamiltonian and Fermi-golden rule, the absorption spectrum on the surface of a TI as a function of the chemical potential, film-thickness and incident photon energy. A linear response theory based calculation is also performed using the Kubo formula to determine the longitudinal optical conductivity whose real part gives absorption as a function of photon frequency. The absorption in materials with Dirac fermions which is significantly higher than in normal THz detectors [3] can be further modulated in a TI by explicitly including the warping term making them highly efficient and tunable photodetectors. [1] M.Hasan and C.Kane, Rev.Mod.Phys. 82, 3045(2010) [2] L.Fu, Phys.Rev.Lett.103, 266801(2009) [3] X.Zhang et al., Phys. Rev B, 82, 245107(2010)

On the interfacial fracture resistance of resin-bonded zirconia and glass-infiltrated graded zirconia

PubMed Central

Chai, Herzl; Kaizer, Marina; Chughtai, Asima; Tong, Hui; Tanaka, Carina; Zhang, Yu

2015-01-01

Objective A major limiting factor for the widespread use of zirconia in prosthetic dentistry is its poor resin-cement bonding capabilities. We show that this deficiency can be overcome by infiltrating the zirconia cementation surface with glass. Current methods for assessing the fracture resistance of resin-ceramic bonds are marred by uneven stress distribution at the interface, which may result in erroneous interfacial fracture resistance values. We have applied a wedge-loaded double-cantilever-beam testing approach to accurately measure the interfacial fracture resistance of adhesively bonded zirconia-based restorative materials. Methods The interfacial fracture energy GC was determined for adhesively bonded zirconia, graded zirconia and feldspathic ceramic bars. The bonding surfaces were subjected to sandblasting or acid etching treatments. Baseline GC was measured for bonded specimens subjected to 7 days hydration at 37 °C. Long-term GC was determined for specimens exposed to 20,000 thermal cycles between 5 and 55 °C followed by 2-month aging at 37 °C in water. The test data were interpreted with the aid of a 2D finite element fracture analysis. Results The baseline and long-term GC for graded zirconia was 2–3 and 8 times that for zirconia, respectively. More significantly, both the baseline and long-term GC of graded zirconia were similar to those for feldspathic ceramic. Significance The interfacial fracture energy of feldspathic ceramic and graded zirconia was controlled by the fracture energy of the resin cement while that of zirconia by the interface. GC for the graded zirconia was as large as for feldspathic ceramic, making it an attractive material for use in dentistry. PMID:26365987

Effects of Substrate Addition on Soil Respiratory Carbon Release Under Long-Term Warming and Clipping in a Tallgrass Prairie

PubMed Central

Jia, Xiaohong; Zhou, Xuhui; Luo, Yiqi; Xue, Kai; Xue, Xian; Xu, Xia; Yang, Yuanhe; Wu, Liyou; Zhou, Jizhong

2014-01-01

Regulatory mechanisms of soil respiratory carbon (C) release induced by substrates (i.e., plant derived substrates) are critical for predicting ecosystem responses to climate change, but the mechanisms are not well understood. In this study, we sampled soils from a long-term field manipulative experiment and conducted a laboratory incubation to explore the role of substrate supply in regulating the differences in soil C release among the experimental treatments, including control, warming, clipping, and warming plus clipping. Three types of substrates (glucose, C3 and C4 plant materials) were added with an amount equal to 1% of soil dry weight under the four treatments. We found that the addition of all three substrates significantly stimulated soil respiratory C release in all four warming and clipping treatments. In soils without substrate addition, warming significantly stimulated soil C release but clipping decreased it. However, additions of glucose and C3 plant materials (C3 addition) offset the warming effects, whereas C4 addition still showed the warming-induced stimulation of soil C release. Our results suggest that long-term warming may inhibit microbial capacity for decomposition of C3 litter but may enhance it for decomposition of C4 litter. Such warming-induced adaptation of microbial communities may weaken the positive C-cycle feedback to warming due to increased proportion of C4 species in plant community and decreased litter quality. In contrast, clipping may weaken microbial capacity for warming-induced decomposition of C4 litter but may enhance it for C3 litter. Warming- and clipping-induced shifts in microbial metabolic capacity may be strongly associated with changes in plant species composition and could substantially influence soil C dynamics in response to global change. PMID:25490701

Effects of substrate addition on soil respiratory carbon release under long-term warming and clipping in a tallgrass prairie.

PubMed

Jia, Xiaohong; Zhou, Xuhui; Luo, Yiqi; Xue, Kai; Xue, Xian; Xu, Xia; Yang, Yuanhe; Wu, Liyou; Zhou, Jizhong

2014-01-01

Regulatory mechanisms of soil respiratory carbon (C) release induced by substrates (i.e., plant derived substrates) are critical for predicting ecosystem responses to climate change, but the mechanisms are not well understood. In this study, we sampled soils from a long-term field manipulative experiment and conducted a laboratory incubation to explore the role of substrate supply in regulating the differences in soil C release among the experimental treatments, including control, warming, clipping, and warming plus clipping. Three types of substrates (glucose, C3 and C4 plant materials) were added with an amount equal to 1% of soil dry weight under the four treatments. We found that the addition of all three substrates significantly stimulated soil respiratory C release in all four warming and clipping treatments. In soils without substrate addition, warming significantly stimulated soil C release but clipping decreased it. However, additions of glucose and C3 plant materials (C3 addition) offset the warming effects, whereas C4 addition still showed the warming-induced stimulation of soil C release. Our results suggest that long-term warming may inhibit microbial capacity for decomposition of C3 litter but may enhance it for decomposition of C4 litter. Such warming-induced adaptation of microbial communities may weaken the positive C-cycle feedback to warming due to increased proportion of C4 species in plant community and decreased litter quality. In contrast, clipping may weaken microbial capacity for warming-induced decomposition of C4 litter but may enhance it for C3 litter. Warming- and clipping-induced shifts in microbial metabolic capacity may be strongly associated with changes in plant species composition and could substantially influence soil C dynamics in response to global change.

Comparison of manual toothbrushes with different bristle designs in terms of cleaning efficacy and potential role on gingival recession

PubMed Central

Cifcibasi, Emine; Koyuncuoglu, Cenker Zeki; Baser, Ulku; Bozacioglu, Busra; Kasali, Kamber; Cintan, Serdar

2014-01-01

Objective: The aim was to compare the efficacy of plaque control and potential effects on gingival recession of the toothbrushes with angled and straight bristles. Materials and Methods: A total of 40 healthy dental students (25 females and 15 males; age range: 23-25 years) participated and two study groups were constituted. Participants were randomly distributed into two groups to use either angled or standard design manual tooth brushes with soft bristles. Oral hygiene indicators and soft tissue levels were monitored for 6 months. Plaque index, gingival index (GI), probing depth, clinical attachment level, and bleeding on probing were measured at six sites. Vertical recession (VR) and horizontal recession (HR) were also recorded. All measurements were repeated at 3 and 6 months. Results: Plaque scores were reduced significantly at 6 months compared to baseline in both groups (P < 0.05 and P < 0.005 in criss-cross and standard design brushes, respectively). Mean GI scores of the criss-cross design were reduced significantly at 6 months (P < 0.05). Inter-group comparisons revealed that gingival recession (GR) values were not statistically significant (P > 0.05) at baseline, 3 and 6 months suggesting no pronounced impact of bristle design in terms of GR (VR = 0.596, HR = 0.572; VR = 0.884, HR = 0.572; VR = 0.884, HR = 0.572 in the groups). Conclusions: Bristle design has little impact on plaque removal capacity of a toothbrush. Both designs are safe enough to prevent GR as long as soft bristle material is used. PMID:25202222

[Cointegration test and variance decomposition for the relationship between economy and environment based on material flow analysis in Tangshan City Hebei China].

PubMed

2015-12-01

The material flow account of Tangshan City was established by material flow analysis (MFA) method to analyze the periodical characteristics of material input and output in the operation of economy-environment system, and the impact of material input and output intensities on economic development. Using econometric model, the long-term interaction mechanism and relationship among the indexes of gross domestic product (GDP) , direct material input (DMI), domestic processed output (DPO) were investigated after unit root hypothesis test, Johansen cointegration test, vector error correction model, impulse response function and variance decomposition. The results showed that during 1992-2011, DMI and DPO both increased, and the growth rate of DMI was higher than that of DPO. The input intensity of DMI increased, while the intensity of DPO fell in volatility. Long-term stable cointegration relationship existed between GDP, DMI and DPO. Their interaction relationship showed a trend from fluctuation to gradual ste adiness. DMI and DPO had strong, positive impacts on economic development in short-term, but the economy-environment system gradually weakened these effects by short-term dynamically adjusting indicators inside and outside of the system. Ultimately, the system showed a long-term equilibrium relationship. The effect of economic scale on economy was gradually increasing. After decomposing the contribution of each index to GDP, it was found that DMI's contribution grew, GDP's contribution declined, DPO's contribution changed little. On the whole, the economic development of Tangshan City has followed the traditional production path of resource-based city, mostly depending on the material input which caused high energy consumption and serous environmental pollution.

Platelet-Rich Fibrin Improves the Viability of Diced Cartilage Grafts in a Rabbit Model.

PubMed

Göral, Ali; Aslan, Cem; Bolat Küçükzeybek, Betül; Işık, Dağhan; Hoşnuter, Mübin; Durgun, Mustafa

2016-04-01

Diced cartilage may be wrapped with synthetic or biological materials before grafting to a recipient site. These materials have unique advantages and disadvantages, and a gold standard is not available. The authors investigated the effects of platelet-rich fibrin (PRF) on the survival of cartilage grafts in a rabbit model. In this experimental study, diced cartilage pieces from the ears of 9 male rabbits were left unwrapped or were wrapped with PRF, oxidized regenerated cellulose, or fascia. Specimens then were placed into subcutaneous pockets prepared on the backs of the rabbits. The animals were sacrificed 2 months after the procedure, and the grafts were excised for macroscopic and histopathologic examination. The cartilage graft wrapped with PRF showed superior viability compared with the cartilage graft wrapped with oxidized regenerated cellulose. No significant differences were found among the other groups. The groups were not significantly different in terms of rates of inflammation, fibrosis, or vascularization. PRF enhances the viability of diced cartilage grafts and should be considered an appropriate biological wrapping material for cartilage grafting. © 2016 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com.

Structure and hemocompatibility of nanocrystalline titanium nitride produced under glow-discharge conditions

NASA Astrophysics Data System (ADS)

Sowińska, Agnieszka; Czarnowska, Elżbieta; Tarnowski, Michał; Witkowska, Justyna; Wierzchoń, Tadeusz

2018-04-01

Significant efforts are being made towards developing novel antithrombotic materials. The purpose of the presented study was to characterize two variants of nitrided surface layers produced on alloy Ti-6Al-4V in different areas of low-temperature plasma - at the plasma potential (TiNp) or at the cathode potential (TiNc). The layers were characterized in terms of their microstructure, surface topography and wettability, and platelet response to the environment of different pH. The produced layers were of the TiN + Ti2N + αTiN-type, but the layer produced at the plasma potential was thinner, smoother and had lower surface free energy compared with that produced at the cathode potential. Biological evaluation demonstrated more fibrinogen buildup, less platelet adhesion and aggregation, and fewer strongly activated platelets on the TiNp surface compared with those parameters on the TiNc surface and on the titanium alloy in its initial state. Interestingly, both surface types were significantly resistant to fibrinogen adsorption and platelet adhesion in the environment of lower pH. In conclusion, the nitrided surface layer produced at the plasma potential is a promising material and this basic information is critical for further development of hemocompatible materials.

Evaluation of volatile aldehydes as discriminating parameters in quality vinegars with protected European geographical indication.

PubMed

Durán-Guerrero, Enrique; Chinnici, Fabio; Natali, Nadia; Riponi, Claudio

2015-09-01

Thirty-six high-quality vinegars with geographical indication belonging to Sherry and Modena areas (vinegars of Jerez, balsamic vinegars of Modena and traditional balsamic vinegars of Modena) with all possible aging periods were analyzed to determine the content of volatile aldehydes. A solid-phase extraction method with in-cartridge derivatization using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine followed by gas chromatography-mass spectrometry was employed. Twenty-two volatile aldehydes were identified and determined in the samples. Analysis of variance provided significant differences among the samples as a function of the type of vinegar, aging time and raw material. Principal component analysis and linear discriminant analysis demonstrated the possibility of discriminating the samples in terms of aging time and raw material. Linear aldehydes and compounds such as furfural, methional, nonenal, hexenal, 2-methylbutanal and i-butyraldehyde were the most significant variables able to discriminate the samples. Aldehyde content of premium quality vinegars is a function of both ageing time and raw material. Their evaluation could be a useful tool with a view to ascertaining vinegar origin and genuineness. © 2014 Society of Chemical Industry.

48 CFR 52.211-5 - Material Requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... materials and by-products generated from, and reused within, an original manufacturing process; provided... readjustments and material replacement. Recovered material means waste materials and by-products recovered or diverted from solid waste, but the term does not include those materials and by-products generated from...

Technology assessment of solar-energy systems. Materials resource and hazardous materials impacts of solar deployment

NASA Astrophysics Data System (ADS)

Schiffman, Y. M.; Tahami, J. E.

1982-04-01

The materials-resource and hazardous-materials impacts were determined by examining the type and quantity of materials used in the manufacture, construction, installation, operation and maintenance of solar systems. The materials requirements were compared with US materials supply and demand data to determine if potential problems exist in terms of future availability of domestic supply and increased dependence on foreign sources of supply. Hazardous materials were evaluated in terms of public and occupational health hazards and explosive and fire hazards. It is concluded that: although large amounts of materials would be required, the US had sufficient industrial capacity to produce those materials; (2) postulated growth in solar technology deployment during the period 1995-2000 could cause some production shortfalls in the steel and copper industry; the U.S. could increase its import reliance for certain materials such as silver, iron ore, and copper; however, shifts to other materials such as aluminum and polyvinylchloride could alleviate some of these problems.

Propellant material compatibility program and results

NASA Technical Reports Server (NTRS)

Toth, L. R.; Cannon, W. A.; Coulbert, C. D.; Long, H. R.

1976-01-01

The effects of long-term (up to 10 years) contact of inert materials with earth-storable propellants were studied for the purpose of designing chemical propulsion system components that can be used for current as well as future planetary spacecraft. The primary experimental work, and results to date are reported. Investigations include the following propellants: hydrazine, hydrazine-hydrazine nitrate blends, monomethyl-hydrazine, and nitrogen tetroxide. Materials include: aluminum alloys, corrosion-resistant steels, and titanium alloys. More than 700 test specimen capsules were placed in long-term storage testing at 43 C in the special material compatibility facility. Material ratings relative to the 10-year requirement have been assigned.

Application of Glow Discharge Plasma to Alter Surface Properties of Materials

NASA Technical Reports Server (NTRS)

Trigwell, Steve; Buhler, Charles R.; Calle, Carlos I.

2005-01-01

Some polymer materials that are considered important for spaceport operations are rendered noncompliant when subjected to the Kennedy Space Center (KSC) Standard electrostatic testing. These materials operate in stringent environmental conditions, such as high humidity. Treating materials that fail electrostatic testing and altering their surface properties so that they become compliant would result in considerable cost savings. Significant improvement in electrostatic dissipation of Saf-T-Vu PVC after treatment with air Atmospheric Plasma Glow Discharge (APGD) was observed and the material now passed the KSC electrostatic test. The O:C ratio on the surface, as monitored by X-ray Photoelectron Spectroscopy, increased from 0.165 tO 0.275 indicating enhanced oxidation, and surface contact angle measurements decreased from 107.5 to 72.6 showing increased hydrophilicity that accounted for the increased conductivity. Monitoring of the aging showed that the materials hydrophobic recovery resulted in it failing the electrostatic test 30 hours after treatment. This was probably due to the out-diffusion of the added Zn, Ba, and Cd salt stabilizers detected on the surface and/or diffusion of low molecular weight oligomers. On going work includes improving the long term hydrophilicity by optimizing the APGD process with different gas mixtures. Treatment of other spaceport materials is also presented.

Bending, force recovery, and D-cones in origami inspired model geometries

NASA Astrophysics Data System (ADS)

Eldar, Theresa; Rozairo, Damith; Croll, Andrew B.

The need for materials with advanced functionality has driven a considerable amount of modern materials science. One idea that has gained significant traction is combining of the ideas Origami and Kirigami with existing materials to build in advanced functionality. In most origami damage is induced in order to trap areas of high curvature in desirable locations in a material. However, the long term and dynamic consequences of local failure are largely unknown. In order to gauge the complex interplay of material properties, relaxation and failure in a set of model thin films, a series of bending and force recovery experiments were carried out. We focus on three materials; polydimethylsiloxane (PDMS), polycarbonate (PC), and polystyrene (PS) chosen for their varying responses to stress. We first measured the load bearing capacity of a single bend in each material, examining the force recovery of bends at various curvatures. Next we examined a doubly folded system in which a single developable cone was created in a similar manner. While the D-cone clearly has massive local consequences for each system, it plays an insignificant role in the system's overall behavior. Finally, we considered higher order combinations of d-cones, ridges and bends. AFOSR under the Young Investigator Program (FA9550-15-1-0168).

Preliminary In-Situ Evaluation of an Innovative, Semi-Flexible Pavement Wearing Course Mixture Using Fast Falling Weight Deflectometer.

PubMed

Pratelli, Chiara; Betti, Giacomo; Giuffrè, Tullio; Marradi, Alessandro

2018-04-16

In the last forty, years semi-flexible pavements have been successfully employed, especially in those areas subjected to heavy and slow-moving loads. They usually comprise a wearing course of Grouted Macadam, a composite pavement material that provides significant advantages in comparison to both concrete and asphalt pavements. On the other hand, the laying process of this material is a two-stage operation, and the realization complexity leads to long realization times and high initial costs. Therefore, the use of semi-flexible pavements has been limited to some fields of application and areas. Recently, an innovative material has been developed to be used as an alternative to Grouted Macadam for semi-flexible pavement wearing course realization. This material should provide similar or even superior characteristics compared to traditional Grouted Macadam. This will reduce semi-flexible pavement construction time and avoid the need for dividing the laying process. This paper presents an experimental program involving the use of FastFWD, as an APT device, to evaluate in-situ properties and performance of this material. The achieved results regarding the validation of this new material by means of FastFWD appear promising both in terms of the material's properties and resistance to dynamic load repetitions.

Finite deformations in pressurized thick-walled circular cylinder with steady state temperature

NASA Astrophysics Data System (ADS)

Sharma, Sanjeev; Sharma, Richa

2017-10-01

In this paper finite elastic and plastic stresses have been investigated using the concept of transition theory with the use of generalized strain measure i.e. nonlinear terms in the displacement are also included which are not included in classical theory. In this paper, we analyze the impact of temperature and pressure on the circular cylinder which is the cause of failure of cylinder. It has been noticed from the results that pressure and temperature play a significant role in the failure of the cylinder. It has been noticed that cylinder made up of the material whose compressibility is at the higher side is best for the designing purpose as compared to cylinder with less compressible material.

Evaluation of proposed Skylab and SSP soap products

NASA Technical Reports Server (NTRS)

Whitmore, F. C.; Durfee, R. L.; Spurlock, J. M.

1973-01-01

Three personal hygiene cleansing agents and one laundry detergent (sodium dodecyl benzene sulfonate), which are all candidates for use on long-duration space missions, were evaluated in terms of dermatological effects on human subjects and effects on microbiological species. None of the four materials exhibited adverse dermatological effects from either skin patch tests of two weeks duration or a simulated Skylab personal hygiene regimen of up to four weeks duration. No significant alterations in skin microflora during the use regimen were found. None of the four materials were found to serve as microbiological support media for the species tested, but a species of air-borne mold was observed to grow rapidly in a neutralized aqueous solution. None of the candidate agents was found to be strongly biocidal.

Combined Material Recycling Study with Aesthetic of Entropy and Place Making

PubMed Central

2015-01-01

Green building is a hot topic today. The place making and urban cultures are also important issues in postindustrial society. The industrial heritage renovation projects provide a research opportunity in combination with both aspects. This paper tries to shed new light on this issue by interdisciplinary methods, to study six Guangzhou industrial heritage renovation projects, giving aesthetic values for six sites concerning place making and culture creation, especially giving an explanation for old building material's aesthetic performance in terms of concepts “entropy” and “archetype.” The conclutions regard: the six places are brand spaces of “authentic Guangzhou” that make local experiential knowledge, emotional significance and creative communities in combination with historical and cultural narratives. PMID:25884021

The Meaning of "Magma"

NASA Astrophysics Data System (ADS)

Bartley, J. M.; Glazner, A. F.; Coleman, D. S.

2016-12-01

Magma is a fundamental constituent of the Earth, and its properties, origin, evolution, and significance bear on issues ranging from volcanic hazards to planetary evolution. Unfortunately, published usages indicate that the term "magma" means distinctly different things to different people and this can lead to miscommunication among Earth scientists and between scientists and the public. Erupting lava clearly is magma; the question is whether partially molten rock imaged at depth and too crystal-rich to flow should also be called magma. At crystal fractions > 50%, flow can only occur via crystal deformation and solution-reprecipitation. As the solid fraction increases to 90% or more, the material becomes a welded crystal framework with melt in dispersed pores and/or along grain boundaries. Seismic images commonly describe such volumes of a few % melt as magma, yet the rheological differences between melt-rich and melt-poor materials make it vital not to confuse a large rock volume that contains a small melt fraction with melt-rich material. To ensure this, we suggest that "magma" be reserved for melt-rich materials that undergo bulk fluid flow on timescales consonant with volcanic eruptions. Other terms should be used for more crystal-rich and largely immobile partially molten rock (e.g., "crystal mush," "rigid sponge"). The distinction is imprecise but useful. For the press, the public, and even earth scientists who do not study magmatic systems, "magma" conjures up flowing lava; reports of a large "magma" body that contains a few percent melt can engender the mistaken perception of a vast amount of eruptible magma. For researchers, physical processes like crystal settling are commonly invoked to account for features in plutonic rocks, but many such processes are only possible in melt-rich materials.

Rational design of anode materials based on Group IVA elements (Si, Ge, and Sn) for lithium-ion batteries.

PubMed

Wu, Xing-Long; Guo, Yu-Guo; Wan, Li-Jun

2013-09-01

Lithium-ion batteries (LIBs) represent the state-of-the-art technology in rechargeable energy-storage devices and they currently occupy the prime position in the marketplace for powering an increasingly diverse range of applications. However, the fast development of these applications has led to increasing demands being placed on advanced LIBs in terms of higher energy/power densities and longer life cycles. For LIBs to meet these requirements, researchers have focused on active electrode materials, owing to their crucial roles in the electrochemical performance of batteries. For anode materials, compounds based on Group IVA (Si, Ge, and Sn) elements represent one of the directions in the development of high-capacity anodes. Although these compounds have many significant advantages when used as anode materials for LIBs, there are still some critical problems to be solved before they can meet the high requirements for practical applications. In this Focus Review, we summarize a series of rational designs for Group IVA-based anode materials, in terms of their chemical compositions and structures, that could address these problems, that is, huge volume variations during cycling, unstable surfaces/interfaces, and invalidation of transport pathways for electrons upon cycling. These designs should at least include one of the following structural benefits: 1) Contain a sufficient number of voids to accommodate the volume variations during cycling; 2) adopt a "plum-pudding"-like structure to limit the volume variations during cycling; 3) facilitate an efficient and permanent transport pathway for electrons and lithium ions; or 4) show stable surfaces/interfaces to stabilize the in situ formed SEI layers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Short-term herbivory has long-term consequences in warmed and ambient high Arctic tundra

NASA Astrophysics Data System (ADS)

Little, Chelsea J.; Cutting, Helen; Alatalo, Juha; Cooper, Elisabeth

2017-02-01

Climate change is occurring across the world, with effects varying by ecosystem and region but already occurring quickly in high-latitude and high-altitude regions. Biotic interactions are important in determining ecosystem response to such changes, but few studies have been long-term in nature, especially in the High Arctic. Mesic tundra plots on Svalbard, Norway, were subjected to grazing at two different intensities by captive Barnacle geese from 2003-2005, in a factorial design with warming by Open Top Chambers. Warming manipulations were continued through 2014, when we measured vegetation structure and composition as well as growth and reproduction of three dominant species in the mesic meadow. Significantly more dead vascular plant material was found in warmed compared to ambient plots, regardless of grazing history, but in contrast to many short-term experiments no difference in the amount of living material was found. This has strong implications for nutrient and carbon cycling and could feed back into community productivity. Dominant species showed increased flowering in warmed plots, especially in those plots where grazing had been applied. However, this added sexual reproduction did not translate to substantial shifts in vegetative cover. Forbs and rushes increased slightly in warmed plots regardless of grazing, while the dominant shrub, Salix polaris, generally declined with effects dependent on grazing, and the evergreen shrub Dryas octopetala declined with previous intensive grazing. There were no treatment effects on community diversity or evenness. Thus despite no changes in total live abundance, a typical short-term response to environmental conditions, we found pronounced changes in dead biomass indicating that tundra ecosystem processes respond to medium- to long-term changes in conditions caused by 12 seasons of summer warming. We suggest that while high arctic tundra plant communities are fairly resistant to current levels of climate warming, underlying ecosystem processes are beginning to change. In addition, even short bouts of intense herbivory can have long-term consequences for some species in these communities.

Correlates of individual, and age-related, differences in short-term learning.

PubMed

Zhang, Zhiyong; Davis, Hasker P; Salthouse, Timothy A; Tucker-Drob, Elliot M

2007-07-01

Latent growth models were applied to data on multitrial verbal and spatial learning tasks from two independent studies. Although significant individual differences in both initial level of performance and subsequent learning were found in both tasks, age differences were found only in mean initial level, and not in mean learning. In neither task was fluid or crystallized intelligence associated with learning. Although there were moderate correlations among the level parameters across the verbal and spatial tasks, the learning parameters were not significantly correlated with one another across task modalities. These results are inconsistent with the existence of a general (e.g., material-independent) learning ability.

The Melting Point of Palladium Using Miniature Fixed Points of Different Ceramic Materials: Part II—Analysis of Melting Curves and Long-Term Investigation

NASA Astrophysics Data System (ADS)

Edler, F.; Huang, K.

2016-12-01

Fifteen miniature fixed-point cells made of three different ceramic crucible materials (Al2O3, ZrO2, and Al2O3(86 %)+ZrO2(14 %)) were filled with pure palladium and used to calibrate type B thermocouples (Pt30 %Rh/Pt6 %Rh). A critical point by using miniature fixed points with small amounts of fixed-point material is the analysis of the melting curves, which are characterized by significant slopes during the melting process compared to flat melting plateaus obtainable using conventional fixed-point cells. The method of the extrapolated starting point temperature using straight line approximation of the melting plateau was applied to analyze the melting curves. This method allowed an unambiguous determination of an electromotive force (emf) assignable as melting temperature. The strict consideration of two constraints resulted in a unique, repeatable and objective method to determine the emf at the melting temperature within an uncertainty of about 0.1 μ V. The lifetime and long-term stability of the miniature fixed points was investigated by performing more than 100 melt/freeze cycles for each crucible of the different ceramic materials. No failure of the crucibles occurred indicating an excellent mechanical stability of the investigated miniature cells. The consequent limitation of heating rates to values below {± }3.5 K min^{-1} above 1100° C and the carefully and completely filled crucibles (the liquid palladium occupies the whole volume of the crucible) are the reasons for successfully preventing the crucibles from breaking. The thermal stability of the melting temperature of palladium was excellent when using the crucibles made of Al2O3(86 %)+ZrO2(14 %) and ZrO2. Emf drifts over the total duration of the long-term investigation were below a temperature equivalent of about 0.1 K-0.2 K.

Five year ground exposure of composite materials used on the Bell Model 206L flight service evaluation

NASA Technical Reports Server (NTRS)

Baker, Donald J.

1989-01-01

Part of the results of a U.S. Army/NASA-Langley sponsored research program to establish the long term-term effects of realistic ground based exposure on advanced composite materials is presented. Residual strengths and moisture absorption as a function of exposure time and exposure location are reported for four different composite material systems that were exposed for five years on the North American Continent.

Prognostic Value of Abnormal p53 Expression in Locally Advanced Prostate Cancer Treated With Androgen Deprivation and Radiotherapy: A Study Based on RTOG 9202

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

Che Mingxin; DeSilvio, Michelle; Pollack, Alan

2007-11-15

Purpose: The goal of this study was to verify the significance of p53 as a prognostic factor in Radiation Therapy Oncology Group 9202, which compared short-term androgen deprivation (STAD) with radiation therapy (RT) to long-term androgen deprivation + RT in men with locally advanced prostate cancer (Pca). Methods and Materials: Tumor tissue was sufficient for p53 analysis in 777 cases. p53 status was determined by immunohistochemistry. Abnormal p53 expression was defined as 20% or more tumor cells with positive nuclei. Univariate and multivariate Cox proportional hazards models were used to evaluate the relationships of p53 status to patient outcomes. Results:more » Abnormal p53 was detected in 168 of 777 (21.6%) cases, and was significantly associated with cause-specific mortality (adjusted hazard ratio [HR] = 1.89; 95% confidence interval (CI) 1.14 - 3.14; p = 0.014) and distant metastasis (adjusted HR = 1.72; 95% CI 1.13-2.62; p = 0.013). When patients were divided into subgroups according to assigned treatment, only the subgroup of patients who underwent STAD + RT showed significant correlation between p53 status and cause-specific mortality (adjusted HR = 2.43; 95% CI = 1.32-4.49; p = 0.0044). When patients were divided into subgroups according to p53 status, only the subgroup of patients with abnormal p53 showed significant association between assigned treatment and cause-specific mortality (adjusted HR = 3.81; 95% CI 1.40-10.37; p = 0.0087). Conclusions: Abnormal p53 is a significant prognostic factor for patients with prostate cancer who undergo short-term androgen deprivation and radiotherapy. Long-term androgen deprivation may significantly improve the cause-specific survival for those with abnormal p53.« less

48 CFR 52.211-5 - Material Requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... readjustments and material replacement. Recovered material means waste materials and by-products recovered or diverted from solid waste, but the term does not include those materials and by-products generated from... is, or with new technology will become, a source of raw materials. (b) Unless this contract otherwise...

Feasibility study of modern airships, phase 1. Volume 2: Parametric analysis (task 3). [lift, weight (mass)

NASA Technical Reports Server (NTRS)

Lancaster, J. W.

1975-01-01

Various types of lighter-than-air vehicles from fully buoyant to semibuoyant hybrids were examined. Geometries were optimized for gross lifting capabilities for ellipsoidal airships, modified delta planform lifting bodies, and a short-haul, heavy-lift vehicle concept. It is indicated that: (1) neutrally buoyant airships employing a conservative update of materials and propulsion technology provide significant improvements in productivity; (2) propulsive lift for VTOL and aerodynamic lift for cruise significantly improve the productivity of low to medium gross weight ellipsoidal airships; and (3) the short-haul, heavy-lift vehicle, consisting of a simple combination of an ellipsoidal airship hull and existing helicopter componentry, provides significant potential for low-cost, near-term applications for ultra-heavy lift missions.

Percutaneous Breast Biopsy: Effect on Short-term Quality of Life

PubMed Central

Humphrey, Kathryn L.; Donelan, Karen; Kong, Chung Y.; Williams, Olubunmi; Itauma, Omosalewa; Halpern, Elkan F.; Gerade, Beverly J.; Rafferty, Elizabeth A.; Swan, J. Shannon

2014-01-01

Purpose To examine the effects of percutaneous breast biopsy on short-term quality of life. Materials and Methods The institutional review board approved this HIPAA-compliant prospective study. From December 1, 2007, through February 28, 2010, women undergoing percutaneous breast biopsy in an academic medical center were recruited to participate in a mixed-mode survey 2–4 days after biopsy. Patients described their biopsy experience by using the Testing Morbidities Index (TMI), a validated instrument for assessing short-term quality of life related to diagnostic testing. The scale ranged from 0 (worst possible experience) to 100 (no adverse effects). Seven attributes were assessed: pain or discomfort before and during testing, fear or anxiety before and during testing, embarrassment during testing, and physical and mental function after testing. Demographic and clinical information were also collected. Univariate and multivariate linear regression analyses were performed to identify significant predictors of TMI score. Results In 188 women (mean age, 51.4 years; range, 22–80 years), the mean TMI score (±standard deviation) was 82 ± 12. Univariate analysis revealed age and race as significant predictors of the TMI score (P < .05). In the multivariate model, only patient age remained a significant independent predictor (P = .001). TMI scores decreased by approximately three points for every decade decrease in patient age, which suggests that younger women were more adversely affected by the biopsy experience. Conclusion Younger patient age is a significant predictor of decreased short-term quality of life related to percutaneous breast biopsy procedures. Tailored prebiopsy counseling may better prepare women for percutaneous biopsy procedures and improve their experience. © RSNA, 2013 PMID:24471385

Long-Term Effect of Loxoprofen Sodium on Nocturia in Patients with Benign Prostatic Hyperplasia

PubMed Central

Shin, Hong Il; Kim, Byung Hoon; Chang, Hyuk Soo; Park, Choal Hee

2011-01-01

Purpose We evaluated the long-term effects of loxoprofen on nocturia in patients with benign prostatic hyperplasia (BPH). Materials and Methods Between January 2006 and December 2008, 40 BPH patients with 2 or more episodes of nocturia received an alpha-blocker, 5-alpha reductase inhibitor, and a single dose of 60 mg of loxoprofen at night before sleep for 12 months (Group I). During the same period, 38 BPH patients selected as the control group received an alpha-blocker and 5-alpha reductase inhibitor (Group II). Patients were reevaluated after 3, 6, and 12 months of treatment by the number of nocturia episodes and side effects. Results After 3 months of treatment, the number of nocturia episodes decreased significantly compared with baseline in both group I and group II (1.9±0.7, 2.1±0.7, respectively, p<0.05). The degree of decrease in nocturia was significantly different between the groups (-1.5±0.9, -1.1±0.9, respectively, p=0.034). After 6 and 12 months, the number of nocturia episodes decreased significantly compared with baseline in both group I and group II (p<0.05), but the degree of decrease was not significantly different between the groups (p>0.05). After 6 and 12 months of treatment in group I, treatment-emergent adverse events, including 5 cases of gastric discomfort (12.5%), 3 cases of leg edema (7.5%), and 1 case of decreased urine volume (2.5%), occurred in 9 of the 40 (22.5%) patients. Conclusions Loxoprofen can be an effective treatment for patients with nocturia secondary to BPH in the short term. Long-term use of loxoprofen is not recommended because of the side effects. PMID:21556213

Hydrogen peroxide bleaching induces changes in the physical properties of dental restorative materials: Effects of study protocols.

PubMed

Yu, Hao; Zhang, Chang-Yuan; Wang, Yi-Ning; Cheng, Hui

2018-03-01

The purpose of this study was to evaluate the influence of study protocols on the effects of bleaching on the surface roughness, substance loss, flexural strength (FS), flexural modulus (FM), Weibull parameters, and color of 7 restorative materials. The test materials included 4 composite resins, 1 glass-ionomer cement, 1 dental ceramic, and 1 polyacid-modified composite. The specimens were randomly divided into 4 groups (n = 20) according to different study protocols: a bleaching group at 25°C (group 25B), a bleaching group at 37°C (group 37B), a control group at 25°C (group 25C), and a control group at 37°C (group 37C). The specimens in the bleaching group were treated with 40% hydrogen peroxide for 80 min at the respective environmental temperatures. The surface roughness, substance loss, FS, FM, and color of the specimens were measured before and after treatment. FS data were also subjected to Weibull analysis, which was used to estimate of the Weibull modulus (m) and the characteristic strength (σ 0 ). Surface roughness increased and significant color changes were observed for all tested specimens after bleaching treatment, except for the ceramic. After bleaching at 37°C, the polyacid-modified composite showed significantly reduced FS, FM, m, and σ 0 values in comparison to the control specimens stored at 37°C in whole saliva. Significant differences were also found between the 37B and 25B polyacid-modified composite groups in terms of surface roughness, FS, m, σ 0 , and color changes. Varying effects of bleaching on the physical properties of dental restorative materials were observed, and the influences of the study protocols on bleaching effects were found to be material-dependent. The influence of study protocols on the effects of bleaching on the surface roughness, flexural properties, and color of dental restorative materials are material-dependent and should be considered when evaluating the effects of bleaching on dental restorative materials. © 2017 Wiley Periodicals, Inc.

Acid Mine Drainage Passive Remediation: Potential Use of Alkaline Clay, Optimal Mixing Ratio and Long Term Impacts

NASA Astrophysics Data System (ADS)

Plaza, F.; Liang, X.; Wen, Y.; Perone, H.

2015-12-01

Acid mine drainage (AMD) is one of the most adverse environmental problems of the mine industry. Surface water and ground water affected by this pollution are characterized by their acidity and the high content of sulfates and heavy metals. In this study, alkaline clay, an industrial waste with a high pH, which is utilized in the alumina refining process, was used as the remediation material to inhibit pyrite oxidation. Through a series of batch and column experiments, complemented with field measurements and geochemical modeling, three important issues associated with this passive and auto sustainable acid mine drainage remediation method were investigated: 1) the potential use of alkaline clay as an AMD remediation material, 2) the adequate alkaline clay/coal refuse mixing ratio (AC/CR) to ensure pH values near to neutral conditions, and, 3) the prediction of long term impacts, in terms of the trends of the main parameters involved in this process such as pH, concentrations of sulfate, iron and other dissolved contaminants. Both field measurements and the samples used for the experiments came from a coal waste site located in Mather, Pennsylvania. Alkaline clay proved to be an effective remediation material for AMD. It was found that 10% AC/CR is an adequate mixing ratio (i.e. the upper limit), which has been also indicated by field measurements. The concentrations of some contaminants such as iron, manganese or sulfate are significantly reduced with the remediation approach, compared to those representative concentrations found in mine tailings. Moreover, results suggest a very reliable long-term stability of the remediation (i.e. neutral pH conditions are maintained), thus enhancing the generation of iron precipitates that could produce pyrite grain coating and hardpan (i.e. cemented layer) on the surface. These processes also made the amended layer less porous, thus increasing water retention and hindering oxygen diffusion.

[Long-term psychiatric hospitalizations].

PubMed

Plancke, L; Amariei, A

2017-02-01

Long-term hospitalizations in psychiatry raise the question of desocialisation of the patients and the inherent costs. Individual indicators were extracted from a medical administrative database containing full-time psychiatric hospitalizations for the period 2011-2013 of people over 16 years old living in the French region of Nord-Pas-de-Calais. We calculated the proportion of people who had experienced a hospitalization with a duration of 292 days or more during the study period. A bivariate analysis was conducted, then ecological data (level of health-care offer, the deprivation index and the size of the municipalities of residence) were included into a multilevel regression model in order to identify the factors significantly related to variability of long-term hospitalization rates. Among hospitalized individuals in psychiatry, 2.6% had had at least one hospitalization of 292 days or more during the observation period; the number of days in long-term hospitalization represented 22.5% of the total of days of full-time hospitalization in psychiatry. The bivariate analysis revealed that seniority in the psychiatric system was strongly correlated with long hospitalization rates. In the multivariate analysis, the individual indicators the most related to an increased risk of long-term hospitalization were: total lack of autonomy (OR=9.0; 95% CI: 6.7-12.2; P<001); diagnoses of psychological development disorders (OR=9.7; CI95%: 4.5-20.6; P<.001); mental retardation (OR=4.5; CI95%: 2.5-8.2; P<.001): schizophrenia (OR=3.0; CI95%: 1.7-5.2; P<.001); compulsory hospitalization (OR=1.7; CI95%: 1.4-2.1; P<.001); having experienced therapeutic isolation (OR=1.8; CI95%: 1.5-2.1; P<.001). Variations of long-term hospitalization rates depending on the type of establishment were very high, but the density of hospital beds or intensity of ambulatory activity services were not significantly linked to long-term hospitalization. The inhabitants of small urban units had significantly less risk of long-term hospitalization than those of large cities. We found no influence of material and social deprivation in the long-term hospitalizations. Long-term hospitalization in psychiatry only concerns a minority of patients but represents the fifth of the total number of days of full-time hospitalization. The recent patients were significantly less exposed to the risk of having a long-term hospitalization. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Acoustic behavior of a fibrous bulk material. [Kevlar 29 sound absorber

NASA Technical Reports Server (NTRS)

Hersh, A. S.; Walker, B.

1979-01-01

A semiempirical model is presented describing the acoustic behavior of Kevlar 29, a bulk absorbing material. The model is based on an approximate solution to the one-dimensional equations representing conservation of fluctuating mass, momentum and energy. By treating the material as a momentum sink, theoretical expressions of the material complex propagation constants and characteristic impedance were derived in terms of a single constant. Evaluating the constant at a single frequency for a particular specimen, excellent agreement between prediction and measurement was achieved for a large range of sound frequencies and material porosities and thicknesses. Results show that Kevlar 29 absorbs sound efficiently even at low frequencies. This is explained in terms of a frequency dependent material phase speed.

The role of material flexibility on the drying transition of water between hydrophobic objects: A thermodynamic analysis

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

Altabet, Y. Elia; Debenedetti, Pablo G., E-mail: pdebene@princeton.edu

2014-11-14

Liquid water confined between hydrophobic objects of sufficient size becomes metastable with respect to its vapor at separations smaller than a critical drying distance. Macroscopic thermodynamic arguments predicting this distance have been restricted to the limit of perfectly rigid confining materials. However, no material is perfectly rigid and it is of interest to account for this fact in the thermodynamic analysis. We present a theory that combines the current macroscopic theory with the thermodynamics of elasticity to derive an expression for the critical drying distance for liquids confined between flexible materials. The resulting expression is the sum of the well-knownmore » drying distance for perfectly rigid confining materials and a new term that accounts for flexibility. Thermodynamic arguments show that this new term is necessarily positive, meaning that flexibility increases the critical drying distance. To study the expected magnitude and scaling behavior of the flexible term, we consider the specific case of water and present an example of drying between thin square elastic plates that are simply supported along two opposite edges and free at the remaining two. We find that the flexible term can be the same order of magnitude or greater than the rigid solution for materials of biological interest at ambient conditions. In addition, we find that when the rigid solution scales with the characteristic size of the immersed objects, the flexible term is independent of size and vice versa. Thus, the scaling behavior of the overall drying distance will depend on the relative weights of the rigid and flexible contributions.« less

The effects of cross-linked thermo-responsive PNIPAAm-based hydrogel injection on retinal function.

PubMed

Turturro, Sanja B; Guthrie, Micah J; Appel, Alyssa A; Drapala, Pawel W; Brey, Eric M; Pérez-Luna, Victor H; Mieler, William F; Kang-Mieler, Jennifer J

2011-05-01

There is significant interest in biomaterials that provide sustained release of therapeutic molecules to the retina. Poly(N-isopropylacrylamide) (PNIPAAm)-based materials have received significant attention as injectable drug delivery platforms due to PNIPAAm's thermo-responsive properties at approximately 32 °C. While the drug delivery properties of PNIPAAm materials have been studied extensively, there is a need to evaluate the safety effects of hydrogel injection on retinal function. The purpose of this study was to examine the effect of poly(ethylene glycol) diacrylate (PEG-DA) crosslinked PNIPAAm hydrogel injection on retinal function. Utilizing scanning laser ophthalmoscopy (SLO), optical coherent tomography (OCT), and electroretinography (ERG), retinal function was assessed following hydrogel injection. In region near the hydrogel, there was a significant decrease in arterial and venous diameters (∼4%) and an increase in venous blood velocity (∼8%) 1 week post-injection. Retinal thickness decreased (∼6%) at 1 week and the maximum a- and b-wave amplitudes of ERG decreased (∼15%). All data returned to baseline values after week 1. These data suggest that the injection of PEG-DA crosslinked PNIPAAm hydrogel results in a small transient effect on retinal function without any long-term effects. These results further support the potential of PNIPAAm-based materials as an ocular drug delivery platform. Copyright © 2011 Elsevier Ltd. All rights reserved.

Accelerated long-term assessment of thermal and chemical stability of bio-based phase change materials

USDA-ARS?s Scientific Manuscript database

Thermal energy storage (TES) systems incorporated with phase change materials (PCMs) have potential applications to control energy use by building envelopes. However, it is essential to evaluate long term performance of the PCMs and cost effectiveness prior to full scale implementation. For this rea...

Analysis of the different source terms of natural radionuclides in a river affected by NORM (Naturally Occurring Radioactive Materials) activities.

PubMed

Baeza, A; Corbacho, J A; Guillén, J; Salas, A; Mora, J C

2011-05-01

The present work studied the radioacitivity impact of a coal-fired power plant (CFPP), a NORM industry, on the water of the Regallo river which the plant uses for cooling. Downstream, this river passes through an important irrigated farming area, and it is a tributary of the Ebro, one of Spain's largest rivers. Although no alteration of the (210)Po or (232)Th content was detected, the (234,238)U and (226)Ra contents of the water were significantly greater immediately below CFPP's discharge point. The (226)Ra concentration decreased progressively downstream from the discharge point, but the uranium content increased significantly again at two sampling points 8 km downstream from the CFPP's effluent. This suggested the presence of another, unexpected uranium source term different from the CFPP. The input from this second uranium source term was even greater than that from the CFPP. Different hypotheses were tested (a reservoir used for irrigation, remobilization from sediments, and the effect of fertilizers used in the area), with it finally being demonstrated that the source was the fertilizers used in the adjacent farming areas. Copyright © 2011 Elsevier Ltd. All rights reserved.

Nanoparticles in Medicine: Selected Observations and Experimental Caveats.

PubMed

Thomsen, Sharon; Pearce, John A; Giustini, Andrew; Hoopes, P Jack

2013-02-26

Medically useful nanoparticles measure 1-100 nm in at least one dimension and are engineered and manufactured for specific diagnostic and treatment applications. Most nanoparticles used currently used in medicine are engineered and manufactured for specific purposes. Medically significant nanoparticles are composed of a 1) central core that is usually the medically active component, 2) one or more layers of organic or inorganic materials that forms a capsule (corona) covering the core and 3) an outer surface layer that interacts with the environment and/or targeted cells and tissues. Effective nanoparticle function in the living, intact animal or human requires electrochemical stability necessary to bypass the reticuloendothelial system (RES) and avoid filtration through the renal glomerulus into the urine. Nanoparticles are present in "natural" as well as the manufacturing and clinical environments thus could pose as significant toxins because of their small sizes, their chemical and drug content and potential effect of causing long term disease including allergies, chronic inflammation and cancer. Currently published studies have focused on the effects of nanoparticles on cells in the extremely artificial environments of cell cultures. More clinical and preclinical studies documenting the short term and long term effects nanoparticle in the intact experimental animal and human are needed.

Nanoparticles in medicine: selected observations and experimental caveats

NASA Astrophysics Data System (ADS)

Thomsen, Sharon; Pearce, John A.; Giustini, Andrew; Hoopes, P. Jack

2013-02-01

Medically useful nanoparticles measure 1-100 nm in at least one dimension and are engineered and manufactured for specific diagnostic and treatment applications. Most nanoparticles used currently used in medicine are engineered and manufactured for specific purposes. Medically significant nanoparticles are composed of a 1) central core that is usually the medically active component, 2) one or more layers of organic or inorganic materials that forms a capsule (corona) covering the core and 3) an outer surface layer that interacts with the environment and/or targeted cells and tissues. Effective nanoparticle function in the living, intact animal or human requires electrochemical stability necessary to bypass the reticuloendothelial system (RES) and avoid filtration through the renal glomerulus into the urine. Nanoparticles are present in " natural" as well as the manufacturing and clinical environments thus could pose as significant toxins because of their small sizes, their chemical and drug content and potential effect of causing long term disease including allergies, chronic inflammation and cancer. Currently published studies have focused on the effects of nanoparticles on cells in the extremely artificial environments of cell cultures. More clinical and preclinical studies documenting the short term and long term effects nanoparticle in the intact experimental animal and human are needed.

Safety of latex urinary catheters for the short time drainage

PubMed Central

Hosseinpour, Mehrdad; Noori, Saeed; Amir-Beigi, Mahdieh; Pourfakharan, Mohammad Hassan; Ehteram, Hassan; Hamsayeh, Mohadese

2014-01-01

Background: In this study, we attempt to identify the most appropriate catheter (silicone vs. latex) for short-term urinary catheterization. We compared the post-operative clinico-pathological complications between latex and silicone for short term catheterization in rabbits with hypospadias. Materials and Methods: Forty rabbits were used in our study to compare complications of catheterization. They were divided in two groups. Hypospadias like defect was created by a 1 cm long excision of the ventral urethra. For urethroplasty, we used tubularized incised plate technique. Latex and silicon catheters were used in groups 1 and 2, respectively. Post-operatively, routine laboratory urine test and complications (allergy, infection, bleeding) were compared in groups. Results: A total of 40 rabbits underwent hypospadias repair. Findings showed that there were no significant differences between groups based on urine test indices (P = NS). Urinary tract infection rate was 10% (2 rabbits) in latex and 0% in silicone groups (P = NS). There were no significant differences between groups regarding of cystitis grades between study groups (P = NS). Conclusion: It seems that urinary tract catheterization with latex catheters is a safe, feasible, and in-expensive procedure for short-term post-operative course in hypospadias surgery in patients without latex hypersensitivity. PMID:25125890

Intracranial aneurysmal pulsatility as a new individual criterion for rupture risk evaluation: biomechanical and numeric approach (IRRAs Project).

PubMed

Sanchez, M; Ecker, O; Ambard, D; Jourdan, F; Nicoud, F; Mendez, S; Lejeune, J-P; Thines, L; Dufour, H; Brunel, H; Machi, P; Lobotesis, K; Bonafe, A; Costalat, V

2014-09-01

The present study follows an experimental work based on the characterization of the biomechanical behavior of the aneurysmal wall and a numerical study where a significant difference in term of volume variation between ruptured and unruptured aneurysm was observed in a specific case. Our study was designed to highlight by means of numeric simulations the correlation between aneurysm sac pulsatility and the risk of rupture through the mechanical properties of the wall. In accordance with previous work suggesting a correlation between the risk of rupture and the material properties of cerebral aneurysms, 12 fluid-structure interaction computations were performed on 12 "patient-specific" cases, corresponding to typical shapes and locations of cerebral aneurysms. The variations of the aneurysmal volume during the cardiac cycle (ΔV) are compared by using wall material characteristics of either degraded or nondegraded tissues. Aneurysms were located on 6 different arteries: middle cerebral artery (4), anterior cerebral artery (3), internal carotid artery (1), vertebral artery (1), ophthalmic artery (1), and basilar artery (1). Aneurysms presented different shapes (uniform or multilobulated) and diastolic volumes (from 18 to 392 mm3). The pulsatility (ΔV/V) was significantly larger for a soft aneurysmal material (average of 26%) than for a stiff material (average of 4%). The difference between ΔV, for each condition, was statistically significant: P=.005. The difference in aneurysmal pulsatility as highlighted in this work might be a relevant patient-specific predictor of aneurysm risk of rupture. © 2014 by American Journal of Neuroradiology.

A short-term, comprehensive, yoga-based lifestyle intervention is efficacious in reducing anxiety, improving subjective well-being and personality

PubMed Central

Yadav, Raj Kumar; Magan, Dipti; Mehta, Manju; Mehta, Nalin; Mahapatra, Sushil Chandra

2012-01-01

Objective: To assess the efficacy of a short-term comprehensive yoga-based lifestyle intervention in reducing anxiety, improving subjective well-being and personality. Materials and Methods: The study is a part of an ongoing larger study at a tertiary care hospital. Participants (n=90) included patients with chronic diseases attending a 10-day, yoga-based lifestyle intervention program for prevention and management of chronic diseases, and healthy controls (n=45) not attending any such intervention. Primary Outcome Measures: Change in state and trait anxiety questionnaire (STAI-Y; 40 items), subjective well-being inventory (SUBI; 40 items), and neuroticism extraversion openness to experience five factor personality inventory revised (NEO-FF PI-R; 60 items) at the end of intervention. Results: Following intervention, the STAI-Y scores reduced significantly (P<0.001) at Day 10 (66.7 ± 13.0) versus Day 1 (72.5 ± 14.7). Also, positive SUBI scores (F1– F6) improved significantly (P<0.01) at Day 10 versus Day 1. Similarly NEO-FF PI-R scores improved significantly (P<0.001) at Day 10 versus Day 1. Control group showed an increase in STAI-Y while SUBI and NEO-FF PI-R scores remained comparable at Day 10 versus Day 1. Conclusions: The observations suggest that a short-term, yoga-based lifestyle intervention may significantly reduce anxiety and improve subjective well-being and personality in patients with chronic diseases. PMID:22869998

Reaction modeling of drainage quality in the Duluth Complex, northern Minnesota, USA

USGS Publications Warehouse

Seal, Robert; Lapakko, Kim; Piatak, Nadine; Woodruff, Laurel G.

2015-01-01

Reaction modeling can be a valuable tool in predicting the long-term behavior of waste material if representative rate constants can be derived from long-term leaching tests or other approaches. Reaction modeling using the REACT program of the Geochemist’s Workbench was conducted to evaluate long-term drainage quality affected by disseminated Cu-Ni-(Co-)-PGM sulfide mineralization in the basal zone of the Duluth Complex where significant resources have been identified. Disseminated sulfide minerals, mostly pyrrhotite and Cu-Fe sulfides, are hosted by clinopyroxene-bearing troctolites. Carbonate minerals are scarce to non-existent. Long-term simulations of up to 20 years of weathering of tailings used two different sets of rate constants: one based on published laboratory single-mineral dissolution experiments, and one based on leaching experiments using bulk material from the Duluth Complex conducted by the Minnesota Department of Natural Resources (MNDNR). The simulations included only plagioclase, olivine, clinopyroxene, pyrrhotite, and water as starting phases. Dissolved oxygen concentrations were assumed to be in equilibrium with atmospheric oxygen. The simulations based on the published single-mineral rate constants predicted that pyrrhotite would be effectively exhausted in less than two years and pH would rise accordingly. In contrast, only 20 percent of the pyrrhotite was depleted after two years using the MNDNR rate constants. Predicted pyrrhotite depletion by the simulation based on the MNDNR rate constant matched well with published results of laboratory tests on tailings. Modeling long-term weathering of mine wastes also can provide important insights into secondary reactions that may influence the permeability of tailings and thereby affect weathering behavior. Both models predicted the precipitation of a variety of secondary phases including goethite, gibbsite, and clay (nontronite).

Determination of Stress Coefficient Terms in Cracked Solids for Monoclinic Materials with Plane Symmetry at x3 = 0

NASA Technical Reports Server (NTRS)

Yuan, F. G.

1998-01-01

Determination of all the coefficients in the crack tip field expansion for monoclinic materials under two-dimensional deformation is presented in this report. For monoclinic materials with a plane of material symmetry at x(sub 3) = 0, the in-plane deformation is decoupled from the anti-plane deformation. In the case of in-plane deformation, utilizing conservation laws of elasticity and Betti's reciprocal theorem, together with selected auxiliary fields, T-stress and third-order stress coefficients near the crack tip are evaluated first from path-independent line integrals. To determine the T-stress terms using the J-integral and Betti's reciprocal work theorem, auxiliary fields under a concentrated force and moment acting at the crack tip are used respectively. Through the use of Stroh formalism in anisotropic elasticity, analytical expressions for all the coefficients including the stress intensity factors are derived in a compact form that has surprisingly simple structure in terms of the Barnett-Lothe tensors, L. The solution forms for degenerated materials, orthotropic, and isotropic materials are presented.

Precipitate strengthening of nanostructured aluminium alloy.

PubMed

Wawer, Kinga; Lewandowska, Malgorzata; Kurzydlowski, Krzysztof J

2012-11-01

Grain boundaries and precipitates are the major microstructural features influencing the mechanical properties of metals and alloys. Refinement of the grain size to the nanometre scale brings about a significant increase in the mechanical strength of the materials because of the increased number of grain boundaries which act as obstacles to sliding dislocations. A similar effect is obtained if nanoscale precipitates are uniformly distributed in coarse grained matrix. The development of nanograin sized alloys raises the important question of whether or not these two mechanisms are "additive" and precipitate strengthening is effective in nanostructured materials. In the reported work, hydrostatic extrusion (HE) was used to obtain nanostructured 7475 aluminium alloy. Nanosized precipitates were obtained by post-HE annealing. It was found that such annealing at the low temperatures (100 degrees C) results in a significant increase in the microhardness (HV0.2) and strength of the nanostructured 7475 aluminium alloy. These results are discussed in terms of the interplay between the precipitation and deformation of nanocrystalline metals.

Radiation Shielding Optimization on Mars

NASA Technical Reports Server (NTRS)

Slaba, Tony C.; Mertens, Chris J.; Blattnig, Steve R.

2013-01-01

Future space missions to Mars will require radiation shielding to be optimized for deep space transit and an extended stay on the surface. In deep space, increased shielding levels and material optimization will reduce the exposure from most solar particle events (SPE) but are less effective at shielding against galactic cosmic rays (GCR). On the surface, the shielding provided by the Martian atmosphere greatly reduces the exposure from most SPE, and long-term GCR exposure is a primary concern. Previous work has shown that in deep space, additional shielding of common materials such as aluminum or polyethylene does not significantly reduce the GCR exposure. In this work, it is shown that on the Martian surface, almost any amount of aluminum shielding increases exposure levels for humans. The increased exposure levels are attributed to neutron production in the shield and Martian regolith as well as the electromagnetic cascade induced in the Martian atmosphere. This result is significant for optimization of vehicle and shield designs intended for the surface of Mars.

Durability of symmetric-structured metal-supported solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Tucker, Michael C.

2017-11-01

Symmetric-structure metal-supported solid oxide fuel cells (MS-SOFC) with YSZ electrolyte are fabricated with porous YSZ backbone electrodes, stainless steel supports, and infiltrated catalysts on both anode and cathode side. Durability towards aggressive thermal and redox cycling, and long-term operation is assessed. Many sealing material candidates are screened for compatibility with the cell materials and operating conditions, and a commercial sealing glass, GM31107, is selected. LSM/SDCN cells are then subjected to 200 very fast thermal cycles and 20 complete redox cycles, with minimal impact to cell performance. LSM/SDCN and SDCN/SDCN cells are operated for more than 1200 h at 700 °C. The seal and cell hermeticity is maintained, and cell ohmic impedance does not change significantly during operation. Electrode polarization increases during operation, leading to significant degradation of the cell performance. In-operando EIS and post-mortem SEM/EDS analysis suggest that catalyst coarsening and cathode Cr deposition are the dominant degradation modes.

Proceedings of the symposium on Nuclear Radiation Detection Materials

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

Perry, D.L.; Burger, A.; Franks, L.

2008-07-01

This symposium provides a venue for the presentation of the latest results and discussion of radiation detection materials from both experimental and theoretical standpoints. As advances are made in this area of materials, additional experimental and theoretical approaches are used to both guide the growth of materials and to characterize the materials that have a wide array of applications for detecting different types of radiation. The types of detector materials for semiconductors and scintillators include a variety of molecular compounds such as lanthanum halides (LaX{sub 3}), zinc oxide (ZnO), lead iodide (PbI{sub 2}), cadmium telluride (CdTe), mercuric iodide (HgI{sub 2}),more » thallium bromide (TlBr), as well as others, such as cadmium zinc telluride (CZT). An additional class of scintillators includes those based on organic compounds and glasses. Ideally, desired materials used for radiation detection have attributes such as appropriate-range band-gaps, high atomic numbers of the central element, high densities, performance at room temperature, and strong mechanical properties, and are low cost in terms of their production. There are significant gaps in the knowledge related to these materials that are very important in making radiation detector materials that are higher quality in terms of their reproducible purity, homogeneity, and mechanical integrity. The topics that are the focal point of this symposium address these issues so that much better detectors may be made in the future. Topics cover the following areas: - Material growth: on-going developments regarding cadmium telluride (CdTe), cadmium zinc telluride (CZT), mercuric iodide (HgI{sub 2}), cadmium manganese telluride (CMT), LaX{sub 3}, and all other detector materials; new materials with potential for radiation detection (II-VI, III-VI, III-VII compounds, neutron detectors, nano-materials, and ceramic scintillators); purification techniques; and growth methods; - Characterization: experimental results; methodologies; defect structure; surface and bulk effects; and interfacial phenomena (contacting, contact adhesion, crystallographic polarity, Schottky barrier, and surface passivation); - Physical and mechanical properties: electric charge compensation mechanisms, charge collection, and thermal transport; hardness; and plasticity; - New and innovative characterization techniques: optical spectroscopy; microscopy (SEM, TEM, STM, AFM, etc.); synchrotron mapping and X-ray diffraction; rocking curves; and spectroscopy (IR, Raman, NMR, XPS, Auger, and other applicable approaches); - Theoretical studies: bandgap calculations; mobility calculations; scintillator material physics; thermal modeling; crystal growth; processes in material matrices; and processes in amorphous and crystalline matrices.« less

Chest physiotherapy during anesthesia for children with cystic fibrosis: effects on respiratory function.

PubMed

Tannenbaum, E; Prasad, S A; Dinwiddie, R; Main, Eleanor

2007-12-01

Physiotherapists sometimes use elective surgical procedures for children with cystic fibrosis as an opportunity to perform physiotherapy treatments during anesthesia. These treatments theoretically facilitate direct endotracheal airway clearance and compensate for any post-operative respiratory deterioration related to the anaesthetic and surgery. MATERIALS, PATIENTS, AND METHODS: Children were randomized either to receive physiotherapy or not following anesthesia and intubation. Respiratory mechanics (C(rs) and R(rs)), tidal volume, and peak inspiratory pressure (PIP) were measured immediately before and after physiotherapy. FEV(1) was measured before and after surgery and post-operative physiotherapy requirements were recorded. Eighteen patients, mean age 12 years (range 2.8-15 years) were recruited, with nine in each group. Both groups showed a non-significant decline in FEV(1) the day after surgery compared with pre-operative values (-5.8%: physiotherapy and -7.1%: control). Both PIP and R(rs) increased significantly following physiotherapy (within- and between-groups, P < 0.05). In addition, there was a significant within-group reduction in C(rs) after physiotherapy which approached significance between-groups (P = 0.07). There were no significant within- or between-group differences in tidal volume following treatment in either group. The unanticipated decline in respiratory function immediately following physiotherapy was short-lived and not discernible in longer term outcomes measured by FEV(1) or physiotherapy requirements post-operatively. If respiratory physiotherapy under anesthesia is considered necessary and the benefits of removing secretions are deemed to outweigh the short-term risks, it may be necessary for the anaesthetist to consider modifying ventilatory support to counteract any short-term negative effects of the treatment.

Surface hardness evaluation of different composite resin materials: influence of sports and energy drinks immersion after a short-term period

PubMed Central

ERDEMİR, Ugur; YİLDİZ, Esra; EREN, Meltem Mert; OZEL, Sevda

2013-01-01

Objectives: This study evaluated the effect of sports and energy drinks on the surface hardness of different composite resin restorative materials over a 1-month period. Material and Methods: A total of 168 specimens: Compoglass F, Filtek Z250, Filtek Supreme, and Premise were prepared using a customized cylindrical metal mould and they were divided into six groups (N=42; n=7 per group). For the control groups, the specimens were stored in distilled water for 24 hours at 37º C and the water was renewed daily. For the experimental groups, the specimens were immersed in 5 mL of one of the following test solutions: Powerade, Gatorade, X-IR, Burn, and Red Bull, for two minutes daily for up to a 1-month test period and all the solutions were refreshed daily. Surface hardness was measured using a Vickers hardness measuring instrument at baseline, after 1-week and 1-month. Data were statistically analyzed using Multivariate repeated measure ANOVA and Bonferroni's multiple comparison tests (α=0.05). Results: Multivariate repeated measures ANOVA revealed that there were statistically significant differences in the hardness of the restorative materials in different immersion times (p<0.001) in different solutions (p<0.001). The effect of different solutions on the surface hardness values of the restorative materials was tested using Bonferroni's multiple comparison tests, and it was observed that specimens stored in distilled water demonstrated statistically significant lower mean surface hardness reductions when compared to the specimens immersed in sports and energy drinks after a 1-month evaluation period (p<0.001). The compomer was the most affected by an acidic environment, whereas the composite resin materials were the least affected materials. Conclusions: The effect of sports and energy drinks on the surface hardness of a restorative material depends on the duration of exposure time, and the composition of the material. PMID:23739850

Polytetrafluoroetylene tape as temporary restorative material: a fluid filtration study.

PubMed

Olcay, Keziban; Steier, Liviu; Erdogan, Hilal

2015-01-01

The purpose of this study was to compare the sealing ability of temporary restorative materials at 24 hrs and 1 week. Endodontic access cavities were prepared in 56 extracted lower incisor-teeth and divided into 5 groups (n=10). Standard 5 mm deep access preparations were completed and root canals were prepared to size ISO #30 file. The access cavities were restored as follows: Group 1: temporary restorative material (Ceivitron); Group 2: glass ionomer cement (Fuji II); Group 3: zinc oxide-eugenol cement (IRM); Group 4: zinc phosphate cement (Adhesor); Group 5: polytetrafluoroetylene tape (PTFE). The quality of the coronal sealing of each specimen was measured (24 hrs and 1 week) using fluid transport model. The data was analyzed with repeated measurements ANOVA, Tukey' HSD and Paired samples T-Tests. A significant difference was found among the groups at all time-periods (p<0.05). At 24 hrs, PTFE showed similar leakage with Ceivitron, IRM, and Fuji II but it showed higher leakage than Adhesor. At 1 week, Ceivitron showed higher leakage than PTFE, meanwhile PTFE showed similar leakage with IRM, Fuji II, and Adhesor (p>0.05). Sealing ability of IRM and PTFE groups significantly increased by time (p<0.05 and p<0.001 respectively). Within the limitations of this study, PTFE showed an acceptable short-term sealing capability when compared to the other commonly used temporary restorative materials at 1 week measurements.

Quantitative assessment of the enamel machinability in tooth preparation with dental diamond burs.

PubMed

Song, Xiao-Fei; Jin, Chen-Xin; Yin, Ling

2015-01-01

Enamel cutting using dental handpieces is a critical process in tooth preparation for dental restorations and treatment but the machinability of enamel is poorly understood. This paper reports on the first quantitative assessment of the enamel machinability using computer-assisted numerical control, high-speed data acquisition, and force sensing systems. The enamel machinability in terms of cutting forces, force ratio, cutting torque, cutting speed and specific cutting energy were characterized in relation to enamel surface orientation, specific material removal rate and diamond bur grit size. The results show that enamel surface orientation, specific material removal rate and diamond bur grit size critically affected the enamel cutting capability. Cutting buccal/lingual surfaces resulted in significantly higher tangential and normal forces, torques and specific energy (p<0.05) but lower cutting speeds than occlusal surfaces (p<0.05). Increasing material removal rate for high cutting efficiencies using coarse burs yielded remarkable rises in cutting forces and torque (p<0.05) but significant reductions in cutting speed and specific cutting energy (p<0.05). In particular, great variations in cutting forces, torques and specific energy were observed at the specific material removal rate of 3mm(3)/min/mm using coarse burs, indicating the cutting limit. This work provides fundamental data and the scientific understanding of the enamel machinability for clinical dental practice. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of size-fractioning techniques on concentrations of selected trace metals in bottom materials from two streams in northeastern Ohio

USGS Publications Warehouse

Koltun, G.F.; Helsel, Dennis R.

1986-01-01

Identical stream-bottom material samples, when fractioned to the same size by different techniques, may contain significantly different trace-metal concentrations. Precision of techniques also may differ, which could affect the ability to discriminate between size-fractioned bottom-material samples having different metal concentrations. Bottom-material samples fractioned to less than 0.020 millimeters by means of three common techniques (air elutriation, sieving, and settling) were analyzed for six trace metals to determine whether the technique used to obtain the desired particle-size fraction affects the ability to discriminate between bottom materials having different trace-metal concentrations. In addition, this study attempts to assess whether median trace-metal concentrations in size-fractioned bottom materials of identical origin differ depending on the size-fractioning technique used. Finally, this study evaluates the efficiency of the three size-fractioning techniques in terms of time, expense, and effort involved. Bottom-material samples were collected at two sites in northeastern Ohio: One is located in an undeveloped forested basin, and the other is located in a basin having a mixture of industrial and surface-mining land uses. The sites were selected for their close physical proximity, similar contributing drainage areas, and the likelihood that trace-metal concentrations in the bottom materials would be significantly different. Statistically significant differences in the concentrations of trace metals were detected between bottom-material samples collected at the two sites when the samples had been size-fractioned by means of air elutriation or sieving. Statistical analyses of samples that had been size fractioned by settling in native water were not measurably different in any of the six trace metals analyzed. Results of multiple comparison tests suggest that differences related to size-fractioning technique were evident in median copper, lead, and iron concentrations. Technique-related differences in copper concentrations most likely resulted from contamination of air-elutriated samples by a feed tip on the elutriator apparatus. No technique-related differences were observed in chromium, manganese, or zinc concentrations. Although air elutriation was the most expensive sizefractioning technique investigated, samples fractioned by this technique appeared to provide a superior level of discrimination between metal concentrations present in the bottom materials of the two sites. Sieving was an adequate lower-cost but more laborintensive alternative.

Searching for the Hebb effect in Down syndrome: evidence for a dissociation between verbal short-term memory and domain-general learning of serial order.

PubMed

Mosse, E K; Jarrold, C

2010-04-01

The Hebb effect is a form of repetition-driven long-term learning that is thought to provide an analogue for the processes involved in new word learning. Other evidence suggests that verbal short-term memory also constrains now vocabulary acquisition, but if the Hebb effect is independent of short-term memory, then it may be possible to demonstrate its preservation in a sample of individuals with Down syndrome, who typically show a verbal short-term memory deficit alongside surprising relative strengths in vocabulary. In two experiments, individuals both with and without Down syndrome (matched for receptive vocabulary) completed immediate serial recall tasks incorporating a Hebb repetition paradigm in either verbal or visuospatial conditions. Both groups demonstrated equivalent benefit from Hebb repetition, despite individuals with Down syndrome showing significantly lower verbal short-term memory spans. The resultant Hebb effect was equivalent across verbal and visuospatial domains. These studies suggest that the Hebb effect is essentially preserved within Down syndrome, implying that explicit verbal short-term memory is dissociable from potentially more implicit Hebb learning. The relative strength in receptive vocabulary observed in Down syndrome may therefore be supported by largely intact long-term as opposed to short-term serial order learning. This in turn may have implications for teaching methods and interventions that present new phonological material to individuals with Down syndrome.

Positive effects of subliminal stimulation on memory.

PubMed

Chakalis, E; Lowe, G

1992-06-01

To assess the effect of subliminally embedded auditory material on short-term recall, 60 volunteer subjects undertook a face-name-occupation memory test before and after a 15-min. intervention. They were randomly assigned into three groups (a control group and two experimental groups) and allocated to one of the following conditions: (1) no sound, (2) supraliminal presentation of relaxing music, and (3) subliminal presentation of memory-improvement affirmations embedded in relaxing music. After intervention, only the subliminal group significantly improved their performance on recall of names.

Beyond the biosphere. [aerospace environments and human life support

NASA Technical Reports Server (NTRS)

Nicogossian, A. E.; Parker, J. F.

1985-01-01

The near-earth-space, planetary and interplanetary environments are described with emphasis on their biomedical significance. The characteristics of the microgravity field, low gravity and radiation conditions in earth orbit are described, noting the necessity of avoiding materials which can outgas toxic substances during long-term mission. Details of the atmospheres, global meteorology, and terrains of Venus, Mars, Jupiter, the Jovian satellites, and Saturn are reviewed. Finally, a brief discussion is provided of the life-support systems which will be required on interstellar voyages.

Short- and medium-term response to storms on three Mediterranean coarse-grained beaches

NASA Astrophysics Data System (ADS)

Grottoli, Edoardo; Bertoni, Duccio; Ciavola, Paolo

2017-10-01

The storm response of three Italian coarse-grained beaches was investigated to better understand the morphodynamics of coarse-clastic beaches in a microtidal context. Two of the studied sites are located on the eastern side of the country (Portonovo and Sirolo) and the third one (Marina di Pisa) is on the western side. Portonovo and Sirolo are mixed sand and gravel beaches where the storms approach from two main directions, SE and NE. Marina di Pisa is a coarse-grained, gravel-dominated beach, exposed to storms driven by SW winds. Gravel nourishments were undertaken in recent years on the three sites. Beach topography was monitored measuring the same network of cross sections at a monthly (i.e. short-term) to seasonal frequency (i.e. medium-term). Geomorphic changes were examined before and after storm occurrences by means of profile analyses and shoreline position evaluations. The beach orientation and the influence of hard structures are the main factors controlling the transport and accumulation of significant amount of sediments and the consequent high variability of beach morphology over the medium-term. For Marina di Pisa, storms tend to accumulate material towards the upper part of the beach with no shoreline rotation and no chance to recover the initial configuration. Sirolo and Portonovo showed a similar behaviour that is more typical of pocket beaches. Both beaches show shoreline rotation after storms in a clockwise or counter-clockwise direction according to the incoming wave direction. The wider and longer beach at Sirolo allows the accumulation of a thin layer of sediment during storms, rather than at Portonovo where, given its longshore and landward boundaries, the beach material tends to accumulate in greater thickness. After storms, Sirolo and especially Portonovo can quickly recover the initial beach configuration, as soon as another storm of comparable energy approaches from the opposite direction of the previous one. Large morphological variations after the storm on mixed sand and gravel beaches do not necessarily mean a slower recovery of surface topography and shoreline position. Considering that all the three beaches were recently nourished with gravel, it emerged that the differences between the nourishment and the native material, in terms of size and composition, seem to have an important influence on the dynamics of the sediment stock. Considering that recent studies have remarked the high abrasion rate of gravel, further understanding of the evolution of nourishment material with time is needed. The peculiar behaviour of gravel material artificially added to an originally sandy beach suggests the need to modify the widely used classification of Jennings and Shulmeister (2002) adding a fourth additional beach typology, which could represent human-altered beaches.

Issues In Space Radiation Protection: Galactic Cosmic Rays

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Kim, M.; Schimmerling, W.; Badavi, F. F.; Thibeault, S. A.; Cucinotta, F. A.; Shinn, J. L.; Kiefer, R.

1995-01-01

When shielding from cosmic heavy ions, one is faced with limited knowledge about the physical properties and biological responses of these radiations. Herein, the current health is discussed in terms of conventional protection practice and a test biological response model. The impact of biological response on optimum materials selection for cosmic ray shielding is presented in terms of the transmission characteristics of the shield material. Although liquid hydrogen is an optimum shield material, evaluation of the effectiveness of polymeric structural materials must await improvement in our knowledge of both the biological response and the nuclear processes.

Readability of online patient education materials for velopharyngeal insufficiency.

PubMed

Xie, Deborah X; Wang, Ray Y; Chinnadurai, Sivakumar

2018-01-01

Evaluate the readability of online and mobile application health information about velopharyngeal insufficiency (VPI). Top website and mobile application results for search terms "velopharyngeal insufficiency", "velopharyngeal dysfunction", "VPI", and "VPD" were analyzed. Readability was determined using 10 algorithms with Readability Studio Professional Edition (Oleander Software Ltd; Vandalia, OH). Subgroup analysis was performed based on search term and article source - academic hospital, general online resource, peer-reviewed journal, or professional organization. 18 unique articles were identified. Overall mean reading grade level was a 12.89 ± 2.9. The highest reading level among these articles was 15.47-approximately the level of a college senior. Articles from "velopharyngeal dysfunction" had the highest mean reading level (13.73 ± 2.11), above "velopharyngeal insufficiency" (12.30 ± 1.56) and "VPI" (11.66 ± 1.70). Articles from peer-reviewed journals had the highest mean reading level (15.35 ± 2.79), while articles from academic hospitals had the lowest (12.81 ± 1.66). There were statistically significant differences in reading levels between the different search terms (P < 0.01) and article source types (P < 0.05). Only one mobile application was identified with VPI information, with a readability of 10.68. Despite published reading level guidelines, online patient education materials for VPI are disseminated with language too complex for most readers. There is also a lack of VPI-related mobile application data available for patients. Patients will benefit if future updates to websites and disseminated patient information are undertaken with health literacy in mind. Future studies will investigate patient comprehension of these materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Nonlinear response and avalanche behavior in metallic glasses

NASA Astrophysics Data System (ADS)

Riechers, B.; Samwer, K.

2017-08-01

The response to different stress amplitudes at temperatures below the glass transition temperature is analyzed by mechanical oscillatory excitation of Pd40Ni40P20 metallic glass samples in single cantilever bending geometry. While low amplitude oscillatory excitations are commonly used in mechanical spectroscopy to probe the relaxation spectrum, in this work the response to comparably high amplitudes is investigated. The strain response of the material is well below the critical yield stress even for highest stress amplitudes, implying the expectation of a linear relation between stress and strain according to Hooke's Law. However, a deviation from the linear behavior is evident, which is analyzed in terms of temperature dependence and influence of the applied stress amplitude by two different approaches of evaluation. The nonlinear approach is based on a nonlinear expansion of the stress-strain-relation, assuming an intrinsic nonlinear character of the shear or elastic modulus. The degree of nonlinearity is extracted by a period-by-period Fourier-analysis and connected to nonlinear coefficients, describing the intensity of nonlinearity at the fundamental and higher harmonic frequencies. The characteristic timescale to adapt to a significant change in stress amplitude in terms of a recovery timescale to a steady state value is connected to the structural relaxation time of the material, suggesting a connection between the observed nonlinearity and primary relaxation processes. The second approach of evaluation is termed the incremental analysis and relates the observed response behavior to avalanches, which occur due to the activation and correlation of local microstructural rearrangements. These rearrangements are connected with shear transformation zones and correspond to localized plastic events, which are superimposed on the linear response behavior of the material.

Using modified polyetheretherketone (PEEK) as an alternative material for endocrown restorations: A short-term clinical report.

PubMed

Zoidis, Panagiotis; Bakiri, Eleonora; Polyzois, Gregory

2017-03-01

A modified polyetheretherketone (PEEK) framework material veneered with indirect light-polymerized composite resin was used as an alternative material for the fabrication of an endocrown restoration for an extensively damaged molar. The elastic modulus of the polyetheretherketone framework (4 GPa) veneered with indirect composite resin could dampen the occlusal forces protecting tooth structures better than ceramic materials. This is important in the restoration of extensively damaged molars with weak roots. Long-term clinical evidence is required before recommending the application as a substitute material. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Flexible plastic, paper and textile lab-on-a chip platforms for electrochemical biosensing.

PubMed

Economou, Anastasios; Kokkinos, Christos; Prodromidis, Mamas

2018-06-26

Flexible biosensors represent an increasingly important and rapidly developing field of research. Flexible materials offer several advantages as supports of biosensing platforms in terms of flexibility, weight, conformability, portability, cost, disposability and scope for integration. On the other hand, electrochemical detection is perfectly suited to flexible biosensing devices. The present paper reviews the field of integrated electrochemical bionsensors fabricated on flexible materials (plastic, paper and textiles) which are used as functional base substrates. The vast majority of electrochemical flexible lab-on-a-chip (LOC) biosensing devices are based on plastic supports in a single or layered configuration. Among these, wearable devices are perhaps the ones that most vividly demonstrate the utility of the concept of flexible biosensors while diagnostic cards represent the state-of-the art in terms of integration and functionality. Another important type of flexible biosensors utilize paper as a functional support material enabling the fabrication of low-cost and disposable paper-based devices operating on the lateral flow, drop-casting or folding (origami) principles. Finally, textile-based biosensors are beginning to emerge enabling real-time measurements in the working environment or in wound care applications. This review is timely due to the significant advances that have taken place over the last few years in the area of LOC biosensors and aims to direct the readers to emerging trends in this field.

Correlation effects and electronic properties of Cr-substituted SZn with an intermediate band.

PubMed

Tablero, C

2005-09-15

A study using first principles of the electronic properties of S32Zn31Cr, a material derived from the SZn host semiconductor where a Cr atom has been substituted for each of the 32 Zn atoms, is presented. This material has an intermediate band sandwiched between the valence and conduction bands of the host semiconductor, which in a formal band-theoretic picture is metallic because the Fermi energy is located within the impurity band. The potential technological application of these materials is that when they are used to absorb photons in solar cells, the efficiency increases significantly with respect to the host semiconductor. An analysis of the gaps, bandwidths, density of states, total and orbital charges, and electronic density is carried out. The main effects of the local-density approximation with a Hubbard term corrections are an increase in the bandwidth, a modification of the relative composition of the five d and p transition-metal orbitals, and a splitting of the intermediate band. The results demonstrate that the main contribution to the intermediate band is the Cr atom. For values of U greater than 6 eV, where U is the empirical Hubbard term U parameter, this band is unfolded, thus creating two bands, a full one below the Fermi energy and an empty one above it, i.e., a metal-insulator transition.

Modeling long-term permafrost degradation

NASA Astrophysics Data System (ADS)

Nicolsky, D.; Romanovsky, V. E.

2017-12-01

Permafrost, as an important part of the Cryosphere, has been also strongly affected by climate warming and a wide spread of the permafrost responses to the warming is currently observed. In particular, at some locations rather slow rates of the permafrost degradations are noticed. We related this behavior to the presence of unfrozen water in frozen fine-grained earth material. In this research, we examine not-very-commonly-discussed heat flux from the ground surface into the permafrost and consequently discuss implications of the unfrozen liquid water content on the long-term thawing of permafrost. We conduct a series of numerical experiments and demonstrate that the presence of fine-grained material with substantial unfrozen liquid water content at below 0C temperature can significantly slow down the thawing rate and hence can increase resilience of permafrost to the warming events. This effect is highly nonlinear and a difference between the rates of thawing in fine- and coarse-grained materials is more drastic for lower values of the incoming into permafrost heat flux. For the high heat flux, the difference between these rates almost disappears. As near-surface permafrost temperature increases towards 0C and the changes in the ground temperature become less evident, the future observation networks should try to incorporate measurements of the unfrozen liquid water content in the near-surface permafrost and heat flux into permafrost in addition to the existing temperature observations.

Long-term biomonitoring of soil contamination using poplar trees: accumulation of trace elements in leaves and fruits.

PubMed

Madejón, P; Ciadamidaro, L; Marañón, T; Murillo, J M

2013-01-01

Phytostabilization aims to immobilize soil contaminants using higher plants. The accumulation of trace elements in Populus alba leaves was monitored for 12 years after a mine spill. Concentrations of As and Pb significantly decreased, while concentrations of Cd and Zn did not significantly over time. Soil concentrations extracted by CaCl2 were measured by ICP-OES and results of As and Pb were below the detection limit. Long-term biomonitoring of soil contamination using poplar leaves was proven to be better suited for the study of trace elements. Plants suitable for phytostabilization must also be able to survive and reproduce in contaminated soils. Concentrations of trace elements were also measured in P. alba fruiting catkins to determine the effect on its reproduction potential. Cadmium and Zn were found to accumulate in fruiting catkins, with the transfer coefficient for Cd significantly greater than Zn. It is possible for trace elements to translocate to seed, which presents a concern for seed germination, establishment and colonization. We conclude that white poplar is a suitable tree for long-term monitoring of soil contaminated with Cd and Zn, and for phytostabilization in riparian habitats, although some caution should be taken with the possible effects on the food web. Supplemental materials are available for this article. Go to the publisher's online edition of International Journal of Phytoremediation to view the supplemental file.

Longitudinal trends with Improvement in Quality of Life after TVT, TVT O and Burch Colposuspension Procedures

PubMed Central

Drahoradova, Petra; Martan, Alois; Svabik, Kamil; Zvara, Karel; Otava, Martin; Masata, Jaromir

2011-01-01

Summary Background Comparison of the quality of life (QoL) trends after TVT, TVT O and Burch colposuspension (BCS) procedures and comparison of long-term subjective and objective outcomes. Material/Methods The study included 215 women who underwent a TVT, TVT O or BCS procedure. We monitored QoL after each procedure and the effect of complications on the QoL as assessed by the IQOL questionnaire over a 3-year period. Results The study was completed by 74.5% of women after TVT, 74.5% after TVT O, and 65.2% after BCS procedure. In the long-term, the QoL improved from 46.9 to 88.7 and remained stable after BCS; after TVT and TVT O, it declined, but only after TVT O was the decline statistically significant compared to BCS. The IQOL for women with post-operative complications has a clear descending tendency. The effect of the complications is highly significant (p<0.001). Only the OAB complication had a statistically significant effect on QoL p<0.001. Preexistent OAB does not negatively affect postoperative results of anti-incontinence surgery. Conclusions There was a statistically significant decline with the longitudinal values of IQOL with TVT O, but not with TVT or BCS. Anti-incontinence operations significantly improve quality of life for women with MI, but compared to the SI group, the quality of life is worse when measured at a longer time interval after the operation. Anti-incontinence operations significantly improve quality of life, and the difference in preoperative status in the long-term follow-up is demonstrable. PMID:21278690

I Want More and Better Cells! – An Outreach Project about Stem Cells and Its Impact on the General Population

PubMed Central

Varela Amaral, Sara; Forte, Teresa; Ramalho-Santos, João; Girão da Cruz, M. Teresa

2015-01-01

Although science and technology impact every aspect of modern societies, there is still an extensive gap between science and society, which impairs the full exercise of citizenship. In the particular case of biomedical research increased investment should be accompanied by parallel efforts in terms of public information and engagement. We have carried out a project involving the production and evaluation of educational contents focused on stem cells - illustrated newspaper chronicles, radio interviews, a comic book, and animated videos - and monitored their impact on the Portuguese population. The study of the outreach materials in a heterogeneous sample of the population suggests that they are valuable tools to disseminate scientific messages, and that this is especially true for the comic-book format. Furthermore, the data showed that clear and stimulating outreach materials, that are able to teach new concepts and to promote critical thinking, increase engagement in science at different levels, depending on the depth of the concepts involved. Additionally, these materials can influence political, social and personal attitudes toward science. These results, together with the importance attributed to scientific research in stem cells by the population sampled, validates the diffusion of such materials as a significant contribution towards an overall public understanding and engagement in contemporary science, and this strategy should thus be considered in future projects. Regardless, stringent quality control must be implemented in order to efficiently communicate accurate scientific developments, and the public stimulated in terms of finding additional sources of reliable information. PMID:26222053

A chemically stable PVD multilayer encapsulation for lithium microbatteries

NASA Astrophysics Data System (ADS)

Ribeiro, J. F.; Sousa, R.; Cunha, D. J.; Vieira, E. M. F.; Silva, M. M.; Dupont, L.; Goncalves, L. M.

2015-10-01

A multilayer physical vapour deposition (PVD) thin-film encapsulation method for lithium microbatteries is presented. Lithium microbatteries with a lithium cobalt oxide (LiCoO2) cathode, a lithium phosphorous oxynitride (LiPON) electrolyte and a metallic lithium anode are under development, using PVD deposition techniques. Metallic lithium film is still the most common anode on this battery technology; however, it presents a huge challenge in terms of material encapsulation (lithium reacts with almost any materials deposited on top and almost instantly begins oxidizing in contact with atmosphere). To prove the encapsulation concept and perform all the experiments, lithium films were deposited by thermal evaporation technique on top of a glass substrate, with previously patterned Al/Ti contacts. Three distinct materials, in a multilayer combination, were tested to prevent lithium from reacting with protection materials and atmosphere. These multilayer films were deposited by RF sputtering and were composed of lithium phosphorous oxide (LiPO), LiPON and silicon nitride (Si3N4). To complete the long-term encapsulation after breaking the vacuum, an epoxy was applied on top of the PVD multilayer. In order to evaluate oxidation state of lithium films, the lithium resistance was measured in a four probe setup (cancelling wires/contact resistances) and resistivity calculated, considering physical dimensions. A lithium resistivity of 0.16 Ω μm was maintained for more than a week. This PVD multilayer exonerates the use of chemical vapour deposition (CVD), glove-box chambers and sample manipulation between them, significantly reducing the fabrication cost, since battery and its encapsulation are fabricated in the same PVD chamber.

Hypervelocity impact facility for simulating materials exposure to impact by space debris

NASA Technical Reports Server (NTRS)

Rose, M. F.; Best, S.; Chaloupka, T.; Stephens, B.; Crawford, G.

1993-01-01

As a result of man's venturing into space, the local debris contributed by his presence exceeds, at some orbital altitudes, that of the natural component. Man's contribution ranges from fuel residue to large derelect satellites that weigh many kilograms. Current debris models are able to predict the growth of the problem and suggest that spacecraft must employ armor or bumper shields for some orbital altitudes now, and that, the problem will become worse as a function of time. The practical upper limit to the velocity distribution is on the order of 40 km/s and is associated with the natural environment. The maximum velocity of the man-made component is in the 14-16 km/s range. The Long Duration Exposure Facility (LDEF) has verified that the 'high probability of impact' particles are in the microgram to milligram range. These particles can have significant effects on coatings, insulators, and thin metallic layers. The surface of thick materials becomes pitted and the local debris component is enhanced by ejecta from the debris spectrum in a controlled environment. The facility capability is discussed in terms of drive geometry, energetics, velocity distribution, diagnostics, and projectile/debris loading. The facility is currently being used to study impact phenomena on Space Station Freedom's solar array structure, other solar array materials, potential structural materials for use in the station, electrical breakdown in the space environment, and as a means of clarifying or duplicating the impact phenomena on the LDEF surfaces. The results of these experiments are described in terms of the mass/velocity distribution incident on selected samples, crater dynamics, and sample geometry.

Mechanical properties of provisional dental materials: A systematic review and meta-analysis

PubMed Central

Bellot-Arcís, Carlos; Pascual-Moscardó, Agustín; Almerich-Silla, José Manuel

2018-01-01

Provisional restorations represent an important phase during the rehabilitation process, knowledge of the mechanical properties of the available materials allows us to predict their clinical performance. At present, there is no systematic review, which supports the clinicians’ criteria, in the selection of a specific material over another for a particular clinical situation. The purpose of this systematic review and meta-analysis was to assess and compare the mechanical properties of dimethacrylates and monomethacrylates used in fabricating direct provisional restorations, in terms of flexural strength, fracture toughness and hardness. This review followed the PRISMA guidelines. The searches were conducted in PubMed, Embase, Web of Science, Scopus, the New York Academy of Medicine Grey Literature Report and were complemented by hand-searching, with no limitation of time or language up to January 10, 2017. Studies that assess and compare the mechanical properties of dimethacrylate- and monomethacrylate-based provisional restoration materials were selected. A quality assessment of full-text articles were performed according to modified ARRIVE and CONSORT criteria and modified Cochrane Collaboration’s tool for in vitro studies. Initially, 256 articles were identified. After removing the duplicates and applying the selection criteria, 24 articles were included in the qualitative synthesis and 7 were included in the quantitative synthesis (meta-analysis). It may be concluded that dimethacrylate-based provisional restorations presented better mechanical behavior than monomethacrylate-based ones in terms of flexural strength and hardness. Fracture toughness showed no significant differences. Within the monomethacrylate group, polymethylmethacrylate showed greater flexural strength than polyethylmethacrylate. PMID:29489883

Bridging the gap in 1(st) year dental material curriculum: A 3 year randomized cross over trial.

PubMed

Gali, Sivaranjani; Shetty, Vibha; Murthy, N S; Marimuthu, P

2015-01-01

Case-oriented small group discussions (COSGDs) can help students to correlate and integrate the basic science of dental materials into clinical application. We used COSGDs along with didactic lectures in dental material curriculum and hypothesized that case-oriented group discussions would be more effective than traditional lecture alone in terms of performance of students, student perception on the above two teaching methodologies and the feasibility in classes of 2010, 2011 and 2012. A total of 170 students were taught using both COSGD and didactic lecture in a randomized controlled crossover trial design. Their performance was assessed through multiple-choice questions (MCQs) as part of the formative assessment, and their perception was assessed through Likert scale questionnaire. The mean difference in the scores between case-oriented group discussions with lecture and didactic lecture showed significant difference only in few topics. Around 94-96% of students perceived COSGD with didactic lecture help them understand theory better; 76-92% of students feel more comfortable asking questions in a group discussion; 89-98% of students feel such discussions motivate them and 91-100% of students agree that discussions make the subject interesting in the respective years of 2010, 2011 and 2012. Effectiveness of COSGD in terms of scores through MCQs is comparable to traditional lecture. However, most of the students perceive COSGD help them understand the theory better; co-relate clinically; more motivating and interesting than a traditional lecture. Feasibility in institution needs more time and resources to conduct COSGD within the dental material curriculum.

Phosphorus in recycling fertilizers - analytical challenges.

PubMed

Krüger, Oliver; Adam, Christian

2017-05-01

The importance of secondary raw materials for phosphorus (P) fertilizer production is expected to increase in the future due to resource depletion, supply risks, and heavy metal contamination of fossil phosphate resources. Municipal wastewater is a promising source for P recovery. In Germany for instance, it contains almost 50% of the total amount of P that is currently applied as mineral fertilizer. Several procedures have been developed to recover and re-use P resulting in a growing number of recycling fertilizers that are currently not regulated in terms of fertilizer efficiency. We tested various materials and matrices for their total P content, solubility of P in neutral ammonium citrate (P nac ) and water, and performed robustness tests to check if existing analytical methods are suitable for those new materials. Digestion with inverse aqua regia was best suited to determine the total P content. P nac sample preparation and analyses were feasible for all matrices. However, we found significant time and temperature dependencies, especially for materials containing organic matter. Furthermore, several materials didn't reach equilibrium during the extractions. Thus, strict compliance of the test conditions is strongly recommended to achieve comparable results. Copyright © 2017 Elsevier Inc. All rights reserved.

Tubular filamentation for laser material processing

PubMed Central

Xie, Chen; Jukna, Vytautas; Milián, Carles; Giust, Remo; Ouadghiri-Idrissi, Ismail; Itina, Tatiana; Dudley, John M.; Couairon, Arnaud; Courvoisier, Francois

2015-01-01

An open challenge in the important field of femtosecond laser material processing is the controlled internal structuring of dielectric materials. Although the availability of high energy high repetition rate femtosecond lasers has led to many advances in this field, writing structures within transparent dielectrics at intensities exceeding 1013 W/cm2 has remained difficult as it is associated with significant nonlinear spatial distortion. This letter reports the existence of a new propagation regime for femtosecond pulses at high power that overcomes this challenge, associated with the generation of a hollow uniform and intense light tube that remains propagation invariant even at intensities associated with dense plasma formation. This regime is seeded from higher order nondiffracting Bessel beams, which carry an optical vortex charge. Numerical simulations are quantitatively confirmed by experiments where a novel experimental approach allows direct imaging of the 3D fluence distribution within transparent solids. We also analyze the transitions to other propagation regimes in near and far fields. We demonstrate how the generation of plasma in this tubular geometry can lead to applications in ultrafast laser material processing in terms of single shot index writing, and discuss how it opens important perspectives for material compression and filamentation guiding in atmosphere. PMID:25753215

Impact of morphological changes of LiNi1/3Mn1/3Co1/3O2 on lithium-ion cathode performances

NASA Astrophysics Data System (ADS)

Cabelguen, Pierre-Etienne; Peralta, David; Cugnet, Mikael; Maillet, Pascal

2017-04-01

Major advances in Li-ion battery technology rely on the nanostructuration of active materials to overcome the severe kinetics limitations of new - cheaper and safer - chemistries. However, opening porosities results in the decrease of volumetric performances, closing the door to significant applications such as portable electronics, electromobility, and grid storage. In this study, we analyze the link between morphologies and performances of model LiNi1/3Mn1/3Co1/3O2 materials. By quantifying exhaustively their microstructures using nitrogen adsorption, mercury intrusion porosimetry, and helium pycnometry, we can discuss how porosities and surface areas are linked to the electrochemical behavior. There is no geometrical parameters that can predict the performances of all our materials. The shape of agglomeration dictates the electrochemical behavior. A huge drop in volumetric performances is measured when microstructure is considered. We show that gravimetric and volumetric power performances are contrary to each other. Highly dense materials exhibit, by far, the best power performances in terms of volumetric figures, so that opening porosities might not be the best strategy, even in non-nanosized materials, for Li-ion battery technology.

Radon exhalation from building materials for decorative use.

PubMed

Chen, Jing; Rahman, Naureen M; Abu Atiya, Ibrahim

2010-04-01

Long-term exposure to radon increases the risk of developing lung cancer. There is considerable public concern about radon exhalation from building materials and the contribution to indoor radon levels. To address this concern, radon exhalation rates were determined for 53 different samples of drywall, tile and granite available on the Canadian market for interior home decoration. The radon exhalation rates ranged from non-detectable to 312 Bq m(-2) d(-1). Slate tiles and granite slabs had relatively higher radon exhalation rates than other decorative materials, such as ceramic or porcelain tiles. The average radon exhalation rates were 30 Bq m(-2) d(-1) for slate tiles and 42 Bq m(-2) d(-1) for granite slabs of various types and origins. Analysis showed that even if an entire floor was covered with a material having a radon exhalation rate of 300 Bq m(-2) d(-1), it would contribute only 18 Bq m(-3) to a tightly sealed house with an air exchange rate of 0.3 per hour. Generally speaking, building materials used in home decoration make no significant contribution to indoor radon for a house with adequate air exchange. Crown Copyright 2010. Published by Elsevier Ltd. All rights reserved.

Long-term results of the use of silicone sheets after diskectomy in the temporomandibular joint: clinical, radiographic and histopathologic findings.

PubMed

Schliephake, H; Schmelzeisen, R; Maschek, H; Haese, M

1999-10-01

The aim of the present study was to evaluate the long-term results of a group of patients who had the disk of the temporomandibular joint (TMJ) removed and permanently replaced by a silicone sheet. The study group comprised 48 patients, treated in the period from 1983 to 1993. In eight patients, the implants had to be removed after an average interval of 5.6 years and they were submitted for histopathological examination. Twenty-five of the 40 patients with silastic implants in place, and five of the 8 patients who had their implants removed, were available for long-term follow-up (mean interval of 7.0 years, SD 2.8 years). Clinical function was rated according to the Helkimo Dysfunction Index and compared to the preoperative findings. Results showed decreased tenderness of muscles and joints to palpation and increased mouth opening, but no statistically significant improvement in joint function. In 4 patients, a decrease in condylar width was found, while another 4 patients presented with thickening of the condyle by appositional bone formation. Histopathology of the failed implants showed scattered fragments of silastic material and dacron fibers with accumulation of histiocytes in immediate contact with the silicone particles and phagocytozed intracellular material. T-lymphocytes were also present in the vicinity of the silicone particles.

Immediate recall influences the effects of pre-encoding stress on emotional episodic long-term memory consolidation in healthy young men.

PubMed

Wolf, Oliver T

2012-05-01

The stress-associated activation of the hypothalamus-pituitary-adrenal axis influences memory. Several studies have supported the notion that post-learning stress enhances memory consolidation, while pre-retrieval stress impairs retrieval. Findings regarding the effects of pre-encoding stress, in contrast, have been rather inconsistent. In the current two studies, the impact of an immediate retrieval task on these effects was explored. In the first study, 24 healthy young male participants were exposed to a psychosocial laboratory stressor (Trier Social Stress Test) or a control condition before viewing positive, negative, and neutral photographs, which were accompanied by a brief narrative. Immediate as well as delayed (24 h later) free recall was assessed. Stress was expected to enhance emotional long-term memory without affecting immediate recall performance. Stress caused a significant increase in salivary cortisol concentrations but had no significant effects on immediate or delayed retrieval performance, even though a trend toward poorer memory of the stress group was apparent. Based on these findings, the second experiment tested the hypothesis that the beneficial effects of stress on emotional long-term memory performance might be abolished by an immediate recall test. In the second study (n = 32), the same design was used, except for the omission of the immediate retrieval test. This time stressed participants recalled significantly more negative photographs compared to the control group. The present study indicates that an immediate retrieval attempt of material studied after stress exposure can prevent or even reverse the beneficial effects of pre-encoding stress on emotional long-term memory consolidation.

Musicians' Memory for Verbal and Tonal Materials under Conditions of Irrelevant Sound

ERIC Educational Resources Information Center

Williamson, Victoria J.; Mitchell, Tom; Hitch, Graham J.; Baddeley, Alan D.

2010-01-01

Studying short-term memory within the framework of the working memory model and its associated paradigms (Baddeley, 2000; Baddeley & Hitch, 1974) offers the chance to compare similarities and differences between the way that verbal and tonal materials are processed. This study examined amateur musicians' short-term memory using a newly adapted…

A new experimental method for the accelerated characterization of composite materials

NASA Technical Reports Server (NTRS)

Yeow, Y. T.; Morris, D. H.; Brinson, H. F.

1978-01-01

The use of composite materials for a variety of practical structural applications is presented and the need for an accelerated characterization procedure is assessed. A new experimental and analytical method is presented which allows the prediction of long term properties from short term tests. Some preliminary experimental results are presented.

16 CFR 640.3 - General requirements for risk-based pricing notices.

Code of Federal Regulations, 2011 CFR

2011-01-01

... notice (“risk-based pricing notice”) in the form and manner required by this part if the person both— (1... of, credit to that consumer that is primarily for personal, family, or household purposes; and (2... directly comparing the material terms offered to each consumer and the material terms offered to other...

Worldwide flight and ground-based exposure of composite materials

NASA Technical Reports Server (NTRS)

Dexter, H. B.; Baker, D. J.

1984-01-01

The long-term durability of those advanced composite materials which are applicable to aircraft structures was discussed. The composite components of various military and commercial aircraft and helicopters were reviewed. Both ground exposure and flight service were assessed in terms of their impact upon composite structure durability. The ACEE Program is mentioned briefly.

Long-term performance of thermoplastic composite material with cotton burr and stem (CBS) as a partial filler

USDA-ARS?s Scientific Manuscript database

Rationale: Cotton burr and stem (CBS) fraction of cotton gin byproducts has shown promise as a fiber filler in thermoplastic composites, with physical and mechanical properties comparable to that made with wood fiber fillers. However, the long-term performance of this composite material is not known...

A Viscoelastic Constitutive Model Can Accurately Represent Entire Creep Indentation Tests of Human Patella Cartilage

PubMed Central

Pal, Saikat; Lindsey, Derek P.; Besier, Thor F.; Beaupre, Gary S.

2013-01-01

Cartilage material properties provide important insights into joint health, and cartilage material models are used in whole-joint finite element models. Although the biphasic model representing experimental creep indentation tests is commonly used to characterize cartilage, cartilage short-term response to loading is generally not characterized using the biphasic model. The purpose of this study was to determine the short-term and equilibrium material properties of human patella cartilage using a viscoelastic model representation of creep indentation tests. We performed 24 experimental creep indentation tests from 14 human patellar specimens ranging in age from 20 to 90 years (median age 61 years). We used a finite element model to reproduce the experimental tests and determined cartilage material properties from viscoelastic and biphasic representations of cartilage. The viscoelastic model consistently provided excellent representation of the short-term and equilibrium creep displacements. We determined initial elastic modulus, equilibrium elastic modulus, and equilibrium Poisson’s ratio using the viscoelastic model. The viscoelastic model can represent the short-term and equilibrium response of cartilage and may easily be implemented in whole-joint finite element models. PMID:23027200

On the configuration of supercapacitors for maximizing electrochemical performance.

PubMed

Zhang, Jintao; Zhao, X S

2012-05-01

Supercapacitors, which are attracting rapidly growing interest from both academia and industry, are important energy-storage devices for acquiring sustainable energy. Recent years have seen a number of significant breakthroughs in the research and development of supercapacitors. The emergence of innovative electrode materials (e.g., graphene) has clearly provided great opportunities for advancing the science in the field of electrochemical energy storage. Conversely, smart configurations of electrode materials and new designs of supercapacitor devices have, in many cases, boosted the electrochemical performance of the materials. We attempt to summarize recent research progress towards the design and configuration of electrode materials to maximize supercapacitor performance in terms of energy density, power density, and cycle stability. With a brief description of the structure, energy-storage mechanism, and electrode configuration of supercapacitor devices, the design and configuration of symmetric supercapacitors are discussed, followed by that of asymmetric and hybrid supercapacitors. Emphasis is placed on the rational design and configuration of supercapacitor electrodes to maximize the electrochemical performance of the device. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Supramolecular assembled three-dimensional graphene hybrids: Synthesis and applications in supercapacitors

NASA Astrophysics Data System (ADS)

Ni, Lubin; Zhang, Wang; Wu, Zhen; Sun, Chunyu; Cai, Yin; Yang, Guang; Chen, Ming; Piao, Yuanzhe; Diao, Guowang

2017-02-01

Graphene-based materials have received worldwide attention in the focus of forefront energy storage investigations. Currently, the design of novel three-dimensional (3D) graphene structures with high energy capability, superior electron and ion conductivity, and robust mechanical flexibility is still a great challenge. Herein, we have successfully demonstrated a novel approach to fabricate 3D assembled graphene through the supramolecular interactions of β-cyclodextrin polymers (β-CDP) with an adamantine end-capped poly(ethylene oxide) polymer linker (PEG-AD). The incorporation of PEG-AD linker into rGO sheets increased the interlayer spacing of rGO sheets to form 3D graphene materials, which can provide efficient 3D electron transfer pathways and ion diffusion channels, and facilitate the infiltration of gel electrolyte. The as-prepared 3D self-assembled graphene materials exhibit significantly improved electrochemical performances of supercapacitor in terms of high specific capacitance, remarkable rate capability, and excellent cycling stability compared to pristine reduced graphene oxide. This study shed new lights to the construction of three dimensional self-assembled graphene materials and their urgent applications in energy storage.

Interlaminar shear fracture toughness and fatigue thresholds for composite materials

NASA Technical Reports Server (NTRS)

Obrien, T. Kevin; Murri, Gretchen B.; Salpekar, Satish A.

1987-01-01

Static and cyclic end notched flexure tests were conducted on a graphite epoxy, a glass epoxy, and graphite thermoplastic to determine their interlaminar shear fracture toughness and fatigue thresholds for delamination in terms of limiting values of the mode II strain energy release rate, G-II, for delamination growth. The influence of precracking and data reduction schemes are discussed. Finite element analysis indicated that the beam theory calculation for G-II with the transverse shear contribution included was reasonably accurate over the entire range of crack lengths. Cyclic loading significantly reduced the critical G-II for delamination. A threshold value of the maximum cyclic G-II below which no delamination occurred after one million cycles was identified for each material. Also, residual static toughness tests were conducted on glass epoxy specimens that had undergone one million cycles without delamination. A linear mixed-mode delamination criteria was used to characterize the static toughness of several composite materials; however, a total G threshold criterion appears to characterize the fatigue delamination durability of composite materials with a wide range of static toughness.

A new yield and failure theory for composite materials under static and dynamic loading

DOE PAGES

Daniel, Isaac M.; Daniel, Sam M.; Fenner, Joel S.

2017-09-12

In order to facilitate and accelerate the process of introducing, evaluating and adopting new material systems, it is important to develop/establish comprehensive and effective procedures of characterization, modeling and failure prediction of composite structures based on the properties of the constituent materials, e. g., fibers, matrix, and the single ply or lamina. A new yield/failure theory is proposed for predicting lamina yielding and failure under multi-axial states of stress including strain rate effects. It is based on the equivalent stress concept derived from energy principles and is expressed in terms of a single criterion. It is presented in the formmore » of master yield and failure envelopes incorporating strain rate effects. The theory can be further adapted and extended to the prediction of in situ first ply yielding and failure (FPY and FPF) and progressive damage of multi-directional laminates under static and dynamic loadings. The significance of this theory is that it allows for rapid screening of new composite materials without extensive testing and offers easily implemented design tools.« less

Chaotic behavior in Casimir oscillators: A case study for phase-change materials.

PubMed

Tajik, Fatemeh; Sedighi, Mehdi; Khorrami, Mohammad; Masoudi, Amir Ali; Palasantzas, George

2017-10-01

Casimir forces between material surfaces at close proximity of less than 200 nm can lead to increased chaotic behavior of actuating devices depending on the strength of the Casimir interaction. We investigate these phenomena for phase-change materials in torsional oscillators, where the amorphous to crystalline phase transitions lead to transitions between high and low Casimir force and torque states, respectively, without material compositions. For a conservative system bifurcation curve and Poincare maps analysis show the absence of chaotic behavior but with the crystalline phase (high force-torque state) favoring more unstable behavior and stiction. However, for a nonconservative system chaotic behavior can take place introducing significant risk for stiction, which is again more pronounced for the crystalline phase. The latter illustrates the more general scenario that stronger Casimir forces and torques increase the possibility for chaotic behavior. The latter is making it impossible to predict whether stiction or stable actuation will occur on a long-term basis, and it is setting limitations in the design of micronano devices operating at short-range nanoscale separations.

Determining the Critical Dose Threshold of Electron-Induced Electron Yield for Minimally Charged Highly Insulating Materials

NASA Astrophysics Data System (ADS)

Hoffmann, Ryan; Dennison, J. R.; Abbott, Jonathan

2006-03-01

When incident energetic electrons interact with a material, they excite electrons within the material to escape energies. The electron emission is quantified as the ratio of emitted electrons to incident particle flux, termed electron yield. Measuring the electron yield of insulators is difficult due to dynamic surface charge accumulation which directly affects landing energies and the potential barrier that emitted electrons must overcome. Our recent measurements of highly insulating materials have demonstrated significant changes in total yield curves and yield decay curves for very small electron doses equivalent to a trapped charge density of <10^10 electrons /cm^3. The Chung-Everhart theory provides a basic model for the behavior of the electron emission spectra which we relate to yield decay curves as charge is allowed to accumulate. Yield measurements as a function of dose for polyimide (Kapton^TM) and microcrystalline SiO2 will be presented. We use our data and model to address the question of whether there is a minimal dose threshold at which the accumulated charge no longer affects the yield.

Experimental studies on effect of Date Seed Ash (DSA) on strength properties of cement sand mortar

NASA Astrophysics Data System (ADS)

Gunarani, G. I.; Chakkravarthy, S. P.

2017-07-01

The need for alternative material for the cement is arising and being compromised by many engineering researchers. However, the growing demand and surging prices of raw materials challenges the constructional field. India, being one of the largest agricultural economy, produces a quantitative volume of agro-waste that is being dumped. In the conventional concrete production, coarse aggregate (CA) plays an important filler material. The initial study on date seed as a replacement for CA was not successful. This study primarily focuses on Date seed ash as a replacement material for ordinary Portland cement. OPC was replaced by Date Palm Seed Ash (DPSA) in the ratio up to 10% in terms of 2% interval. The main objective of this paper was to study the variation of strength properties of mortar by DPSA in specified ratio along with curing period of 3,7,14 and 28 days. The stress strain behavior has indicated a significant improvement. The overall results indicated the increase in replacing ratio, decreases the strength properties. However the physical, chemical and mechanical properties increased gradually in strength in minimal ratio.

A new yield and failure theory for composite materials under static and dynamic loading

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

Daniel, Isaac M.; Daniel, Sam M.; Fenner, Joel S.

In order to facilitate and accelerate the process of introducing, evaluating and adopting new material systems, it is important to develop/establish comprehensive and effective procedures of characterization, modeling and failure prediction of composite structures based on the properties of the constituent materials, e. g., fibers, matrix, and the single ply or lamina. A new yield/failure theory is proposed for predicting lamina yielding and failure under multi-axial states of stress including strain rate effects. It is based on the equivalent stress concept derived from energy principles and is expressed in terms of a single criterion. It is presented in the formmore » of master yield and failure envelopes incorporating strain rate effects. The theory can be further adapted and extended to the prediction of in situ first ply yielding and failure (FPY and FPF) and progressive damage of multi-directional laminates under static and dynamic loadings. The significance of this theory is that it allows for rapid screening of new composite materials without extensive testing and offers easily implemented design tools.« less

Effect of long-term proton pump inhibitor administration on gastric mucosal atrophy: A meta-analysis

PubMed Central

Li, Zhong; Wu, Cong; Li, Ling; Wang, Zhaoming; Xie, Haibin; He, Xiaozhou; Feng, Jin

2017-01-01

Background/Aims: Proton pump inhibitors (PPIs) are widely used for the treatment of acid-related gastrointestinal diseases. Recently, some studies have reported that PPIs can alter the gastric mucosal architecture; however, the relationship remains controversial. This meta-analysis study was designed to quantify the association between long-term PPI administration and gastric atrophy. Materials and Methods: A PubMed search was conducted to identify studies using the keywords proton pump inhibitors or PPI and gastric atrophy or atrophic gastritis; the timeframe of publication searched was up to May 2016. Heterogeneity among studies was tested with the Q test; odds ratios (OR) and 95% confidence intervals (CI) were calculated. P values were calculated by I2 tests and regarded as statistically significant when <0.05. Results: We identified 13 studies that included 1465 patients under long-term PPI therapy and 1603 controls, with a total gastric atrophy rate of 14.50%. There was a higher presence of gastric atrophy (15.84%; statistically significant) in PPI group compared to the control group (13.29%) (OR: 1.55, 95% CI: 1.00–2.41). Conclusions: The pooled data suggest that long-term PPI use is associated with increased rates of gastric atrophy. Large-scale multicenter studies should be conducted to further investigate the relationship between acid suppressants and precancerous diseases. PMID:28721975

Application of micro-porous polycarbonate membranes in dye-sensitized solar cells: Cell performance and long-term stability

NASA Astrophysics Data System (ADS)

Lue, Shingjiang Jessie; Lo, Pei Wen; Hung, Ling-Yung; Tung, Yung Liang

This research investigates the cell performance and long-term stability of dye-sensitized solar cells (DSSCs) containing micro-porous polycarbonate (PC) film as the frame work material to stabilize the electrolyte solution. The track-etched PC film has cylindrical pore geometry, which is beneficial for ion transport in the electrolyte trapped inside the PC film. The photovoltaic efficiency of the DSSC with 0.2-μm PC membrane is 5.75 ± 0.73% under irradiation of 100 mW cm -2, which is slightly lower than that (6.34 ± 0.44%) of cells without PC film. The differences in fill factor and open-circuit voltage between the DSSCs with and without PC film are not statistically significant. The long-term cell performance is carried out at continuous illumination of 100 mW cm -2 (1 sun) and in darkness at 60 °C for up to 1000 h. There is no significant efficiency difference between the cells with and without PC film in light soaking (4.33% vs. 4.52%) for 960 h. In darkness, however, the cells with PC film demonstrate much higher efficiency (at 2.37%) than cells without PC (0.85%) after 1000 h. The improved long-term efficiency data and the higher percentage of working cells confirm the superior lifetime and performance using the micro-porous PC film.

Removal rate model for magnetorheological finishing of glass.

PubMed

Degroote, Jessica E; Marino, Anne E; Wilson, John P; Bishop, Amy L; Lambropoulos, John C; Jacobs, Stephen D

2007-11-10

Magnetorheological finishing (MRF) is a deterministic subaperture polishing process. The process uses a magnetorheological (MR) fluid that consists of micrometer-sized, spherical, magnetic carbonyl iron (CI) particles, nonmagnetic polishing abrasives, water, and stabilizers. Material removal occurs when the CI and nonmagnetic polishing abrasives shear material off the surface being polished. We introduce a new MRF material removal rate model for glass. This model contains terms for the near surface mechanical properties of glass, drag force, polishing abrasive size and concentration, chemical durability of the glass, MR fluid pH, and the glass composition. We introduce quantitative chemical predictors for the first time, to the best of our knowledge, into an MRF removal rate model. We validate individual terms in our model separately and then combine all of the terms to show the whole MRF material removal model compared with experimental data. All of our experimental data were obtained using nanodiamond MR fluids and a set of six optical glasses.

Preliminary In-Situ Evaluation of an Innovative, Semi-Flexible Pavement Wearing Course Mixture Using Fast Falling Weight Deflectometer

PubMed Central

Pratelli, Chiara; Betti, Giacomo; Marradi, Alessandro

2018-01-01

In the last forty, years semi-flexible pavements have been successfully employed, especially in those areas subjected to heavy and slow-moving loads. They usually comprise a wearing course of Grouted Macadam, a composite pavement material that provides significant advantages in comparison to both concrete and asphalt pavements. On the other hand, the laying process of this material is a two-stage operation, and the realization complexity leads to long realization times and high initial costs. Therefore, the use of semi-flexible pavements has been limited to some fields of application and areas. Recently, an innovative material has been developed to be used as an alternative to Grouted Macadam for semi-flexible pavement wearing course realization. This material should provide similar or even superior characteristics compared to traditional Grouted Macadam. This will reduce semi-flexible pavement construction time and avoid the need for dividing the laying process. This paper presents an experimental program involving the use of FastFWD, as an APT device, to evaluate in-situ properties and performance of this material. The achieved results regarding the validation of this new material by means of FastFWD appear promising both in terms of the material’s properties and resistance to dynamic load repetitions. PMID:29659543

Asbestos-containing materials and airborne asbestos levels in industrial buildings in Korea.

PubMed

Choi, Sangjun; Suk, Mee-Hee; Paik, Nam Won

2010-03-01

Recently in Korea, the treatment of asbestos-containing materials (ACM) in building has emerged as one of the most important environmental health issues. This study was conducted to identify the distribution and characteristics of ACM and airborne asbestos concentrations in industrial buildings in Korea. A total of 1285 presumed asbestos-containing material (PACM) samples were collected from 80 workplaces across the nation, and 40% of the PACMs contained more than 1% of asbestos. Overall, 94% of the surveyed workplaces contained ACM. The distribution of ACM did not show a significant difference by region, employment size, or industry. The total ACM area in the buildings surveyed was 436,710 m2. Ceiling tile ACM accounted for 61% (267,093 m2) of the total ACM area, followed by roof ACM (32%), surfacing ACM (6.1%), and thermal system insulation (TSI). In terms of asbestos type, 98% of total ACM was chrysotile, while crocidolite was not detected. A comparison of building material types showed that the material with the highest priority for regular management is ceiling tile, followed by roof, TSI, and surfacing material. The average airborne concentration of asbestos sampled without disturbing in-place ACM was 0.0028 fibers/cc by PCM, with all measurements below the standard of recommendation for indoor air quality in Korea (0.01 fibers/cc).

Correlation between cavitation erosion resistance and cyclic mechanical properties of different metallic materials

NASA Astrophysics Data System (ADS)

Kaufhold, Corinna; Pöhl, Fabian; Theisen, Werner

2017-05-01

Machine components in contact with flowing fluids are especially prone to cavitation erosion, where plastic deformation and material loss occur due to the repeated implosion of cavitation bubbles in the vicinity of a solid surface. Identifying a correlation between experimentally derivable material properties and resistance against cavitation erosion could help improve the lifetime of cavitation-affected components. Cavitation erosion is a predominantly fatigue-driven phenomenon. In this investigation, we conducted nanoindentation experiments to examine cyclic micromechanical material properties in response to an increasing number of cycles. The experiments were performed on pure iron and different steel grades, i.e., austenitic stainless CrMnCN steels, interstitially alloyed with carbon and nitrogen. We confirmed the view, also proposed in literature, that indentation hardness is inappropriate for ordering the investigated materials by incubation period or maximum erosion rate. We found that the percentage increase of nanoindentation contact stiffness, after an increasing number of cycles, is a promising indicator in terms of the overall ranking of cavitation erosion resistance among the considered materials. Although a single cavitation impact is associated with a significantly higher strain rate than nanoindentation experiments, it is shown that the plastically deformed area around each indent exhibits indications of deformation, such as the formation of slip lines that are also observable after cavitation-induced impacts.

Graphene and its elemental analogue: A molecular dynamics view of fracture phenomenon

NASA Astrophysics Data System (ADS)

Rakib, Tawfiqur; Mojumder, Satyajit; Das, Sourav; Saha, Sourav; Motalab, Mohammad

2017-06-01

Graphene and some graphene like two dimensional materials; hexagonal boron nitride (hBN) and silicene have unique mechanical properties which severely limit the suitability of conventional theories used for common brittle and ductile materials to predict the fracture response of these materials. This study revealed the fracture response of graphene, hBN and silicene nanosheets under different tiny crack lengths by molecular dynamics (MD) simulations using LAMMPS. The useful strength of these two dimensional materials are determined by their fracture toughness. Our study shows a comparative analysis of mechanical properties among the elemental analogues of graphene and suggested that hBN can be a good substitute for graphene in terms of mechanical properties. We have also found that the pre-cracked sheets fail in brittle manner and their failure is governed by the strength of the atomic bonds at the crack tip. The MD prediction of fracture toughness shows significant difference with the fracture toughness determined by Griffth's theory of brittle failure which restricts the applicability of Griffith's criterion for these materials in case of nano-cracks. Moreover, the strengths measured in armchair and zigzag directions of nanosheets of these materials implied that the bonds in armchair direction have the stronger capability to resist crack propagation compared to zigzag direction.

Effects of a constructed Technosol on mortality, survival and reproduction of earthworms

NASA Astrophysics Data System (ADS)

Pey, Benjamin; Cortet, Jerome; Capowiez, Yvan; Mignot, Lenaic; Nahmani, Johanne; Watteau, Francoise; Schwartz, Christophe

2010-05-01

Soils, whose properties and pedogenesis are dominated by artificial materials or transported materials, are classified as Technosols. Some of these Technosols are used in soil engineering, which is the voluntary action to combine technical materials in a given objective to restore an ecosystem. Primary by products that are used to build these Technosols need to be assessed on an ecotoxicological point of view. The following study aims to assess the effects of a constructed Technosol made from different primary by-products on the mortality, survival and reproductions of two earthworm species. The model of Technosol used here is a combination of green-waste compost (GWC) and papermill sludge (PS) mixed with thermally treated industrial soil (TIS). OECD soil is used as a control soil. Three different experiments have been managed: i) the first, to assess the potential toxicity effect on Eisenia foetida biomass (28 days) and reproduction (56 days), ii) the second to assess the short-term effect (7 days) on Lumbricus terrestris biomass, iii) and the third to assess the medium-term effect (30 days) on L. terrestris biomass. Reproduction of E. foetida is enhanced with high proportions of GWC. For biomass, GWC seems to improve body mass contrary to other materials which lead to losses of body mass. Thus, for E. foetida, GWC seems to be a high-quality and long-term source of food. Body mass of L. terrestris decreased with GWC and OECD. At short-term only, TIS/PS leads to a gain of body mass. Only equilibrium of 25% GWC - 75% TIS/PS allows a gain of body mass at medium term. TIS/PS appears to be a low-quality and short-term food resource but an excellent water tank. It can be concluded that the constructed Technosol is not toxic for fauna but some differences appear between different tested material combinations, depending on nature, proportion and trophic properties of materials.