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1

Evaluation of thermal control materials degradation in simulated space environment  

NASA Astrophysics Data System (ADS)

Indian Space Research Organisation (ISRO) has been actively pursuing research and development of a host of materials to be used for its satellite and launch vehicle programs. A variety of thermal control materials have been developed in-house for use in 10-15 years in the LEO and GEO orbits. The present study was carried out [1] to evaluate the effect of synergistic radiation on the thermal control materials and verify the assumptions of BOL and EOL values of materials including White paints, second-surface mirrors, aluminized films of polyimide and polyester, White anodisation and Germanium tapes. The space environment simulation using UV, protons and electrons was carried out at ONERA using a combined radiation test facility. A long term test extending to over three months in vacuum was performed to simulate a three years exposure on the N-S panels in the geostationary orbit for a three axis stabilized spacecraft. Reflectance spectra were measured in-situ in the solar range (250-2500 nm) enabling the evaluation of initial air to vacuum transition effects and the final transition (nitrogen and air exposure effects). This is in addition to the investigation of the UV and particulate radiation induced degradation over three years, measured by steps of 0.5 year. Little spectral water desorption effect occurred during initial transition whereas large bleaching of degradation happened (e.g. in white paint) when the first nitrogen inlet was permitted during return to ambient atmospheric pressure. This bleaching effect increased on exposure to air and continued for one week. Specific spectral bleaching of degradations were observed in the infrared on some samples where UV provoked bleaching of previous step particles degradation. The solar absorptance values were deduced from the reflectance data. The degradation has been observed most in white paints and white anodisation while the second surface mirrors and aluminium paint have been quite stable. Empiric degradation models have been applied on the most degraded materials to extrapolate the degradation for long duration exposure. To complete the thermo-optical properties investigations, infrared emissivity measurements were performed in air at the beginning and end of test showing a good stability, except in the case of polyimide and FEP based thermal control materials.

Marco, J.; Bhojaraj, H.; Hulyal, R.

2003-09-01

2

Evaluating Degradation on Thermal Control Materials for GPM/DPR  

NASA Astrophysics Data System (ADS)

Thermal control materials such as white paints and germanium-coated polyimide film were evaluated with respect to their space environmental tolerance for materials selection of the Dual-frequency Precipitation Radar of the Global Precipitation Measurement satellite (GPM/DPR). Though peeling off and cracking occurred in one paint material during the thermal shock test, other paints showed good tolerance against thermal shock, atomic oxygen, and ultraviolet ray irradiation. Germanium coating on polyimide film was also verified as high atomic oxygen tolerant barrier. Comparing different thickness germanium coatings, it seems that a 1000 angstrom Germanium film has fewer defects and risk of AO undercutting than a 525 angstrom Germanium film.

Ishizawa, Junichiro; Hyakusoku, Yasutoshi; Shimamura, Hiroyuki; Kimoto, Yugo; Kojima, Masahiro

3

Semiconductor CMP Process Control Predicting Degradation Effect of Consumed Materials  

NASA Astrophysics Data System (ADS)

This paper describes a methodology to build a virtual metrology (VM) model for semiconductor chemical mechanical polishing (CMP) process control. The VM model predicts the polishing rate based on equipment-derived data as soon as allowed, and immediately applies the results to advanced process control (APC). The proposed methodology uses Markov chain Monte Carlo (MCMC) methods to build an analytical model with many parameters for individual consumed materials from historical data in small quantities. The mutual interference of two kinds of consumed materials: dresser and pad are modeled in a form of multilevel predictive model. The methodology uses MCMC methods again to identify the multilevel predictive model taking into account the assumed operation of an actual manufacturing line, for instance, using preliminary test result, learning a model parameter online, and being affected by metrology lag as disturbance. The simulation results show the APC with the proposed VM model is low sensitivity to metrology lag and high precision on polishing amount control.

Tamaki, Kenji; Kaneko, Shun'ichi

4

Degradation of thermal control materials under a simulated radiative space environment  

NASA Astrophysics Data System (ADS)

A spacecraft with a passive thermal control system utilizes various thermal control materials to maintain temperatures within safe operating limits. Materials used for spacecraft applications are exposed to harsh space environments such as ultraviolet (UV) and particle (electron, proton) irradiation and atomic oxygen (AO), undergo physical damage and thermal degradation, which must be considered for spacecraft thermal design optimization and cost effectiveness. This paper describes the effect of synergistic radiation on some of the important thermal control materials to verify the assumptions of beginning-of-life (BOL) and end-of-life (EOL) properties. Studies on the degradation in the optical properties (solar absorptance and infrared emittance) of some important thermal control materials exposed to simulated radiative geostationary space environment are discussed. The current studies are purely related to the influence of radiation on the degradation of the materials; other environmental aspects (e.g., thermal cycling) are not discussed. The thermal control materials investigated herein include different kind of second-surface mirrors, white anodizing, white paints, black paints, multilayer insulation materials, varnish coated aluminized polyimide, germanium coated polyimide, polyether ether ketone (PEEK) and poly tetra fluoro ethylene (PTFE). For this purpose, a test in the constant vacuum was performed reproducing a three year radiative space environment exposure, including ultraviolet and charged particle effects on North/South panels of a geostationary three-axis stabilized spacecraft. Reflectance spectra were measured in situ in the solar range (250-2500 nm) and the corresponding solar absorptance values were calculated. The test methodology and the degradations of the materials are discussed. The most important degradations among the low solar absorptance materials were found in the white paints whereas the rigid optical solar reflectors remained quite stable. Among the high solar absorptance elements, as such the change in the solar absorptance was very low, in particular the germanium coated polyimide was found highly stable.

Sharma, A. K.; Sridhara, N.

2012-11-01

5

Degradation of Hubble Space Telescope Metallized Teflon(trademark) FEP Thermal Control Materials  

NASA Technical Reports Server (NTRS)

The mechanical and optical properties of the metallized Teflon Fluorinated Ethylene Propylene (FEP) thermal control materials on the Hubble Space Telescope (HST) have degraded over the seven years the telescope has been in orbit. Astronaut observations and photographic documentation from the Second Servicing Mission revealed severe cracks of the multi-layer insulation (MLI) blanket outer layer in many locations around the telescope, particularly on solar facing surfaces. Two samples, the outer Teflon FEP MLI layer and radiator surfaces, were characterized post- mission through exhaustive mechanical, thermal, chemical, and optical testing. The observed damage to the thermal control materials, the sample retrieval and handling, and the significant changes to the radiator surfaces of HST will be discussed. Each of these issues is addressed with respect to current and future mission requirements.

Hansen, Patricia A.; Townsend, Jacqueline A.; Yoshikawa, Yukio; Castro, J. David; Triolo, Jack J.; Peters, Wanda C.

1998-01-01

6

Final report for the designed synthesis of controlled degradative materials LDRD  

SciTech Connect

The main goal of this research was to develop degradable systems either by developing weaklink-containing polymers or identifying commercial polymeric systems which are easily degraded. In both cases, the degradation method involves environmentally friendly chemistries. The weaklinks are easily degradable fragments which are introduced either randomly or regularly in the polymer backbone or as crosslinking sites to make high molecular weight systems via branching. The authors targeted three general application areas: (1) non-lethal deterrents, (2) removable encapsulants, and (3) readily recyclable/environmentally friendly polymers for structural and thin film applications.

LOY,DOUGLAS A.; ULIBARRI,TAMARA A.; CURRO,JOHN G.; SAUNDERS,R.; DERZON,DORA K.; GUESS,TOMMY R.; BAUGHER,B.M.

2000-02-01

7

Methods for degrading lignocellulosic materials  

DOEpatents

The present invention relates to methods for degrading a lignocellulosic material, comprising: treating the lignocellulosic material with an effective amount of one or more cellulolytic enzymes in the presence of at least one surfactant selected from the group consisting of a secondary alcohol ethoxylate, fatty alcohol ethoxylate, nonylphenol ethoxylate, tridecyl ethoxylate, and polyoxyethylene ether, wherein the presence of the surfactant increases the degradation of lignocellulosic material compared to the absence of the surfactant. The present invention also relates to methods for producing an organic substance, comprising: (a) saccharifying a lignocellulosic material with an effective amount of one or more cellulolytic enzymes in the presence of at least one surfactant selected from the group consisting of a secondary alcohol ethoxylate, fatty alcohol ethoxylate, nonylphenol ethoxylate, tridecyl ethoxylate, and polyoxyethylene ether, wherein the presence of the surfactant increases the degradation of lignocellulosic material compared to the absence of the surfactant; (b) fermenting the saccharified lignocellulosic material of step (a) with one or more fermenting microorganisms; and (c) recovering the organic substance from the fermentation.

Vlasenko, Elena (Davis, CA); Cherry, Joel (Davis, CA); Xu, Feng (Davis, CA)

2011-05-17

8

Methods for degrading lignocellulosic materials  

SciTech Connect

The present invention relates to methods for degrading a lignocellulosic material, comprising: treating the lignocellulosic material with an effective amount of one or more cellulolytic enzymes in the presence of at least one surfactant selected from the group consisting of a secondary alcohol ethoxylate, fatty alcohol ethoxylate, nonylphenol ethoxylate, tridecyl ethoxylate, and polyoxyethylene ether, wherein the presence of the surfactant increases the degradation of lignocellulosic material compared to the absence of the surfactant. The present invention also relates to methods for producing an organic substance, comprising: (a) saccharifying a lignocellulosic material with an effective amount of one or more cellulolytic enzymes in the presence of at least one surfactant selected from the group consisting of a secondary alcohol ethoxylate, fatty alcohol ethoxylate, nonylphenol ethoxylate, tridecyl ethoxylate, and polyoxyethylene ether, wherein the presence of the surfactant increases the degradation of lignocellulosic material compared to the absence of the surfactant; (b) fermenting the saccharified lignocellulosic material of step (a) with one or more fermentating microoganisms; and (c) recovering the organic substance from the fermentation.

Vlasenko, Elena (Davis, CA); Cherry, Joel (Davis, CA); Xu, Feng (Davis, CA)

2008-04-08

9

Degradation of FEP thermal control materials returned from the Hubble Space Telescope  

SciTech Connect

After an initial 3.6 years of space flight, the Hubble Space Telescope was serviced through a joint effort with the NASA and the European Space Agency. Multi-layer insulation (MLI) was retrieved from the electronics boxes of the two magnetic sensing systems (MSS), also called the magnetometers, and from the returned solar array (SA-I) drive arm assembly. The top layer of each MLI assembly is fluorinated ethylene propylene (FEP, a type of Teflon). Dramatic changes in material properties were observed when comparing areas of high solar fluence to areas of low solar fluence. Cross sectional analysis shows atomic oxygen (AO) erosion values up to 25.4 mu m (1 mil). Greater occurrences of through-thickness cracking and surface microcracking were observed in areas of high solar exposure. Atomic force microscopy (AFM) showed increases in surface microhardness measurements with increasing solar exposure. Decreases in FEP tensile strength and elongation were measured when compared to non-flight material. Erosion yield and tensile results are compared with FEP data from the Long Duration Exposure Facility. AO erosion yield data, solar fluence values, contamination, micrometeoroid or debris impact sites, and optical properties are presented.

Zuby, T.M.; Degroh, K.K.; Smith, D.C.

1995-12-01

10

Degradation of FEP thermal control materials returned from the Hubble Space Telescope  

NASA Technical Reports Server (NTRS)

After an initial 3.6 years of space flight, the Hubble Space Telescope was serviced through a joint effort with the NASA and the European Space Agency. Multi-layer insulation (MLI) was retrieved from the electronics boxes of the two magnetic sensing systems (MSS), also called the magnetometers, and from the returned solar array (SA-I) drive arm assembly. The top layer of each MLI assembly is fluorinated ethylene propylene (FEP, a type of Teflon). Dramatic changes in material properties were observed when comparing areas of high solar fluence to areas of low solar fluence. Cross sectional analysis shows atomic oxygen (AO) erosion values up to 25.4 mu m (1 mil). Greater occurrences of through-thickness cracking and surface microcracking were observed in areas of high solar exposure. Atomic force microscopy (AFM) showed increases in surface microhardness measurements with increasing solar exposure. Decreases in FEP tensile strength and elongation were measured when compared to non-flight material. Erosion yield and tensile results are compared with FEP data from the Long Duration Exposure Facility. AO erosion yield data, solar fluence values, contamination, micrometeoroid or debris impact sites, and optical properties are presented.

Zuby, Thomas M.; Degroh, Kim K.; Smith, Daniela C.

1995-01-01

11

Environmental degradation using functionally graded material approach  

E-print Network

Environmental degradation using functionally graded material approach I. Sevostianov a,*, N of the laminate. Ã? 2003 Elsevier Ltd. All rights reserved. Keywords: Degradation; Functionally graded; Microcracks and combine the properties of the damaged and undamaged layer to obtain bulk material properties

Sevostianov, Igor

12

Self-degradable Cementitious Sealing Materials  

Microsoft Academic Search

A self-degradable alkali-activated cementitious material consisting of a sodium silicate activator, slag, Class C fly ash, and sodium carboxymethyl cellulose (CMC) additive was formulated as one dry mix component, and we evaluated its potential in laboratory for use as a temporary sealing material for Enhanced Geothermal System (EGS) wells. The self-degradation of alkali-activated cementitious material (AACM) occurred, when AACM heated

T. Sugama; T. Butcher; Bour Lance Brothers

2010-01-01

13

Degradation of Materials in Combustion Environments  

E-print Network

Degradation mechanisms in conventional refratories, structural ceramics, and metallic alloys were revealed by examination of materials exposed to industrial and synthetic flue gases. Deterioration of refractory oxides and oxide structural ceramics...

Robbins, J. M.; Federer, J. I.; Parks, W. P. Jr.; Reid, J. S.

14

Material Corrion/Degradation Database  

SciTech Connect

The corrosion of a variety of structural metals and materials is presented. Data on specific material--and for well-studied agents--has been abstracted from the corrosion literature. In addition, limited data on one superacid (so-called ''Magic Acid,'' a mixture of 100% fluorosulfonic acid, HSO{sub 3}F, with 25% (w/w) of antimony pentafluoride (SbF{sub 5}) added) is tabulated.

Kinkead, S.A.

1999-07-08

15

Designing degradable hydrogels for orthogonal control of cell microenvironments  

PubMed Central

Degradable and cell-compatible hydrogels can be designed to mimic the physical and biochemical characteristics of native extracellular matrices and provide tunability of degradation rates and related properties under physiological conditions. Hence, such hydrogels are finding widespread application in many bioengineering fields, including controlled bioactive molecule delivery, cell encapsulation for controlled three-dimensional culture, and tissue engineering. Cellular processes, such as adhesion, proliferation, spreading, migration, and differentiation, can be controlled within degradable, cell-compatible hydrogels with temporal tuning of biochemical or biophysical cues, such as growth factor presentation or hydrogel stiffness. However, thoughtful selection of hydrogel base materials, formation chemistries, and degradable moieties is necessary to achieve the appropriate level of property control and desired cellular response. In this review, hydrogel design considerations and materials for hydrogel preparation, ranging from natural polymers to synthetic polymers, are overviewed. Recent advances in chemical and physical methods to crosslink hydrogels are highlighted, as well as recent developments in controlling hydrogel degradation rates and modes of degradation. Special attention is given to spatial or temporal presentation of various biochemical and biophysical cues to modulate cell response in static (i.e., non-degradable) or dynamic (i.e., degradable) microenvironments. This review provides insight into the design of new cell-compatible, degradable hydrogels to understand and modulate cellular processes for various biomedical applications. PMID:23609001

Kharkar, Prathamesh M.

2013-01-01

16

Dedication to Degradation: The Beauty of Materials Designed to Lay in Ruin  

NASA Astrophysics Data System (ADS)

Degradation of materials is typically perceived to be a negative response in service. Many designs, and materials, have been and are ruined due to corrosion, fatigue, weathering, ultraviolet light, fungal attack, bacterial attack, erosion, wear, electromigration… and on the list goes. However, the carefully controlled and purposeful degradation of materials is a prerequisite for success for some designs—and such ability is a beautiful necessity when it comes to many regenerative biomaterials. In other instances, we must seek first to understand the degradation mechanisms before we can achieve degradation prevention—and the resistance of some materials to degradation is also beautiful. Regardless of whether we try to prevent or elicit degradation, our dedication to degradation of materials is ever present in materials design.

Nychka, John A.; Kruzic, Jaime

2014-04-01

17

Tuning the Degradation Profiles of Poly(l-lactide)-Based Materials through Miscibility  

PubMed Central

The effective use of biodegradable polymers relies on the ability to control the onset of and time needed for degradation. Preferably, the material properties should be retained throughout the intended time frame, and the material should degrade in a rapid and controlled manner afterward. The degradation profiles of polyester materials were controlled through their miscibility. Systems composed of PLLA blended with poly[(R,S)-3-hydroxybutyrate] (a-PHB) and polypropylene adipate (PPA) with various molar masses were prepared through extrusion. Three different systems were used: miscible (PLLA/a-PHB5 and PLLA/a-PHB20), partially miscible (PLLA/PPA5/comp and PLLA/PPA20/comp), and immiscible (PLLA/PPA5 and PLLA/PPA20) blends. These blends and their respective homopolymers were hydrolytically degraded in water at 37 °C for up to 1 year. The blends exhibited entirely different degradation profiles but showed no diversity between the total degradation times of the materials. PLLA presented a two-stage degradation profile with a rapid decrease in molar mass during the early stages of degradation, similar to the profile of PLLA/a-PHB5. PLLA/a-PHB20 presented a single, constant linear degradation profile. PLLA/PPA5 and PLLA/PPA20 showed completely opposing degradation profiles relative to PLLA, exhibiting a slow initial phase and a rapid decrease after a prolonged degradation time. PLLA/PPA5/comp and PLLA/PPA20/comp had degradation profiles between those of the miscible and the immiscible blends. The molar masses of the materials were approximately the same after 1 year of degradation despite their different profiles. The blend composition and topographical images captured at the last degradation time point demonstrate that the blending component was not leached out during the period of study. The hydrolytic stability of degradable polyester materials can be tailored to obtain different and predetermined degradation profiles for future applications. PMID:24279455

2013-01-01

18

Geochemistry Model Validation Report: Material Degradation and Release Model  

SciTech Connect

The purpose of this Analysis and Modeling Report (AMR) is to validate the Material Degradation and Release (MDR) model that predicts degradation and release of radionuclides from a degrading waste package (WP) in the potential monitored geologic repository at Yucca Mountain. This AMR is prepared according to ''Technical Work Plan for: Waste Package Design Description for LA'' (Ref. 17). The intended use of the MDR model is to estimate the long-term geochemical behavior of waste packages (WPs) containing U. S . Department of Energy (DOE) Spent Nuclear Fuel (SNF) codisposed with High Level Waste (HLW) glass, commercial SNF, and Immobilized Plutonium Ceramic (Pu-ceramic) codisposed with HLW glass. The model is intended to predict (1) the extent to which criticality control material, such as gadolinium (Gd), will remain in the WP after corrosion of the initial WP, (2) the extent to which fissile Pu and uranium (U) will be carried out of the degraded WP by infiltrating water, and (3) the chemical composition and amounts of minerals and other solids left in the WP. The results of the model are intended for use in criticality calculations. The scope of the model validation report is to (1) describe the MDR model, and (2) compare the modeling results with experimental studies. A test case based on a degrading Pu-ceramic WP is provided to help explain the model. This model does not directly feed the assessment of system performance. The output from this model is used by several other models, such as the configuration generator, criticality, and criticality consequence models, prior to the evaluation of system performance. This document has been prepared according to AP-3.10Q, ''Analyses and Models'' (Ref. 2), and prepared in accordance with the technical work plan (Ref. 17).

H. Stockman

2001-09-28

19

Degradation of Spacecraft Materials in the Space Environment  

NASA Technical Reports Server (NTRS)

When we think of space, we typically think of a vacuum containing very little matter that lies between the Earth and other planetary and stellar bodies. However, the space above Earth's breathable atmosphere and beyond contains many things that make designing durable spacecraft a challenge. Depending on where the spacecraft is flyng, it may encounter atomic oxygen, ultraviolet and other forms of radiation, charged particles, micrormeteoroids and debris, and temperature extremes. These environments on their own and in combination can cause degradation and failure of polymers, composites, paints and other materials used on the exterior of spacecraft for thermal control, structure, and power generation. This article briefly discusses and gives examples of some of the degradation experienced on spacecraft and night experiments as a result of the space environment and the use of ground and space data to predict durability.

Miller, Sharon K. R.; Banks, Bruce A.

2010-01-01

20

Microbial degradation of Phaeocystis material in the water column  

NASA Astrophysics Data System (ADS)

Observational evidence shows that the large amounts of mucilaginous substances produced by blooms of Phaeocystis colonies largely resist rapid microbial degradation in surface waters of most Phaeocystis-dominated ecosystems. In this paper the biodegradability of Phaeocystis colony-derived material is analysed with respect to current knowledge and novel data on the chemical nature of Phaeocystis material in relationship with specific bacterial enzymatic activities. Particular emphasis is given to the chemical nature of Phaeocystis colony matrix which constitutes more than 80% of total colony biomass at maximum development. This analysis gives evidence of the potential biodegradability of this mucilaginous material made of nutrient-deprived polysaccharides. Other factors controlling microbial degradation as the production of antibacterial substances by Phaeocystis colonies, cold temperature and lack of inorganic nitrogen and phosphate are further considered. It is concluded that nutrient limitation currently observed at the senescent stage of Phaeocystis blooms might well explain the low biodegradability of Phaeocystis material. However the lack of bacteria attached to colonies during the exponential phase of Phaeocystis bloom development are not clearly understood and needs further investigations.

Thingstad, F.; Billen, G.

1994-04-01

21

Aging Management Using Proactive Management of Materials Degradation  

NASA Astrophysics Data System (ADS)

The U.S. Nuclear Regulatory Commission (NRC) has undertaken a program to lay the technical foundations for defining proactive actions to manage degradation of materials in light water reactors. The current focus is existing plants; however, if applied to new construction, there is potential to better monitor and manage plants throughout their life cycle. This paper discusses the NRC's Proactive Management of Materials Degradation program and its application to nuclear power plant structures, systems, and components.

Doctor, S. R.; Bond, L. J.; Cumblidge, S. E.; Bruemmer, S. M.; Taylor, W. B.; Carpenter, C. E.; Hull, A. B.; Malik, S. N.

2010-02-01

22

Preferential Degradation of Lignin in Gramineous Materials.  

National Technical Information Service (NTIS)

By fermenting gramineous agricultural plant materials with the basidiomycete Cyathus stercoreus, the lignin and cellulose components are differentially modified. The resultant fermentate enriched in free cellulose has utility as an upgraded ruminant feed ...

D. T. Wicklow, R. W. Detroy

1980-01-01

23

Degradation of experimental composite materials and in vitro wear simulation  

NASA Astrophysics Data System (ADS)

The material, mechanical, and clinical aspects of surface degradation of resin composite dental restorative materials by in vitro wear simulation continues to be an area of active research. To investigate wear mechanisms, a series of experimental resin composites with variable and controlled filler particle shape and loading were studied by in vitro wear simulation. The current investigation utilized a simulation that isolated the wear environment, entrapped high and low modulus debris, and evaluated the process including machine and fluid flow dynamics. The degradation was significantly affected by filler particle shape and less by particle loading. The spherical particle composites demonstrated wear loss profiles suggesting an optimized filler loading may exist. This was also demonstrated by the trends in the mechanical properties. Very little difference in magnitude was noted for the wear of irregular particle composites as a function of particulate size; and as a group they were more wear resistant than spherical particle composites. This was the result of different mechanisms of wear that were correlated with the three-dimensional particle shape. The abrasive effects of the aggregate particles and the polymeric stabilization of the irregular shape versus the destabilization and "plucking" of the spherical particles resulted in an unprotected matrix that accounted for significantly greater wear of spherical composite. A model and analysis was developed to explain the events associated with the progressive material wear loss. The initial phase was explained by fatigue-assisted microcracking and loss of material segments in a zone of high stress immediately beneath a point of high stress contact. The early phase was characterized by the development of a small facet primarily by fatigue-assisted microcracking. Although the translation effects were minimal, some three-body and initial two-body wear events were also present. In the late phases, the abrasive effects of the debris aggregate predominated the wear process. The non-linear rate of wear loss was accelerated as the facet deepened. Physical effects, such as thermal fatigue, and chemical effects were less important but contributed to the degradation process. This study provides new insight into the role(s) of high modulus third body debris in the wear of dental composites.

Givan, Daniel Allen

2001-12-01

24

Hubble Space Telescope Metallized Teflon(registered trademark) FEP Thermal Control Materials: On-Orbit Degradation and Post-Retrieval Analysis  

NASA Technical Reports Server (NTRS)

During the Hubble Space Telescope (HST) Second Servicing Mission (SM2), degradation of unsupported Teflon(Registered Trademark) FEP (fluorinated ethylene propylene), used as the outer layer of the multilayer insulation (MLI) blankets, was evident as large cracks on the telescope light shield. A sample of the degraded outer layer was retrieved during the mission and returned to Earth for ground testing and evaluation. The results of the Teflon(Registered Trademark) FEP sample evaluation and additional testing of pristine Teflon(Registered Trademark) FEP led the investigative team to theorize that the HST damage was caused by thermal cycling with deep-layer damage from electron and proton radiation which allowed the propagation of cracks along stress concentrations , and that the damage increased with the combined total dose of electrons, protons, UV and x-rays along with thermal cycling. This paper discusses the testing and evaluation of the retrieved Teflon(Registered Trademark) FEP.

Townsend, Jacqueline A.; Hansen, Patricia A.; Dever, J. A.; deGroh, K. K.; Banks, B.; Wang, L.; He, C.

1988-01-01

25

Satellite charging control materials  

NASA Astrophysics Data System (ADS)

The secondary emission conductivity of silica fabrics and silica fabric/FEP/Aluminum composites under low energy electron irradiation has been studied. The dependence on electrical field of the conductivity across the samples has been shown. The surface potentials depend on the flux rate; the presence of low energy electron acting together with medium energy electrons decrease the potential values; the potential values increase with the time of exposure to vacuum and/or irradition, as well as with contamination build up. Teflon based conductive SSM with ITO coatings proved to be extremely vulnerable to thermal cycling and water absorption. A grounding technique based on a filled silicone adhesive proved to be applicable to this Teflon based material and was stable during prequalification tests. The degradation of the samples was due to failure in the ITO coating rather than to a failure in the bonding/grounding technique.

Levy, L.; Paillous, A.; Sarrail, D.

1981-06-01

26

Materials Degradation and Detection (MD2): Deep Dive Final Report  

SciTech Connect

An effort is underway at Pacific Northwest National Laboratory (PNNL) to develop a fundamental and general framework to foster the science and technology needed to support real-time monitoring of early degradation in materials used in the production of nuclear power. The development of such a capability would represent a timely solution to the mounting issues operators face with materials degradation in nuclear power plants. The envisioned framework consists of three primary and interconnected “thrust” areas including 1) microstructural science, 2) behavior assessment, and 3) monitoring and predictive capabilities. A brief state-of-the-art assessment for each of these core technology areas is discussed in the paper.

McCloy, John S.; Montgomery, Robert O.; Ramuhalli, Pradeep; Meyer, Ryan M.; Hu, Shenyang Y.; Li, Yulan; Henager, Charles H.; Johnson, Bradley R.

2013-02-01

27

MATERIAL CONTROL ACCOUNTING INMM  

SciTech Connect

Since 1996, the Mining and Chemical Combine (MCC - formerly known as K-26), and the United States Department of Energy (DOE) have been cooperating under the cooperative Nuclear Material Protection, Control and Accounting (MPC&A) Program between the Russian Federation and the U.S. Governments. Since MCC continues to operate a reactor for steam and electricity production for the site and city of Zheleznogorsk which results in production of the weapons grade plutonium, one of the goals of the MPC&A program is to support implementation of an expanded comprehensive nuclear material control and accounting (MC&A) program. To date MCC has completed upgrades identified in the initial gap analysis and documented in the site MC&A Plan and is implementing additional upgrades identified during an update to the gap analysis. The scope of these upgrades includes implementation of MCC organization structure relating to MC&A, establishing material balance area structure for special nuclear materials (SNM) storage and bulk processing areas, and material control functions including SNM portal monitors at target locations. Material accounting function upgrades include enhancements in the conduct of physical inventories, limit of error inventory difference procedure enhancements, implementation of basic computerized accounting system for four SNM storage areas, implementation of measurement equipment for improved accountability reporting, and both new and revised site-level MC&A procedures. This paper will discuss the implementation of MC&A upgrades at MCC based on the requirements established in the comprehensive MC&A plan developed by the Mining and Chemical Combine as part of the MPC&A Program.

Hasty, T.

2009-06-14

28

Analytical and Experimental Studies of the Degradation in Hydrogenated Amorphous Silicon Solar Cells and Materials.  

NASA Astrophysics Data System (ADS)

An improved understanding of a-Si:H pin solar cells stability was obtained by studying light induced degradation in a-Si:H films and in devices. The current -voltage characteristics and the quantum efficiencies of a-Si:H pin solar cells were measured as a function of intrinsic layer thickness, bias light intensity and degradation condition. Photoconductivity measurements on device quality intrinsic a-Si:H thin film materials showed that the majority carrier (electron) mutau product degraded from 3times 10^{-7}rm cm ^2/V to 2times 10^{ -7}rm cm^2/V after 6 minutes of 50-Suns light illumination. Using a dual beam technique with steady white light and modulated monochromatic light, a degradation profile was detected in the degraded materials. These results suggest that inhomogeneous degradation may be important to understanding the stability of a-Si:H pin solar cells. An analytical model was developed for degradation in a-Si:H pin solar cells based on inhomogeneous degradation, which was used to explain the 'blue-dip' effect observed in the quantum efficiencies of degraded cells. A new method was developed to investigate the minority carrier (hole) diffusion length in device quality a-Si:H films as a function of degradation. This method uses the Schottky barrier structure to establish a depletion region, which can be controlled by the applied voltage and the bias light intensity. Modulated blue light is used to generate electron hole pairs near the ohmic contacts, and the holes diffuse across the neutral region to be collected. The modulated current is related to the diffusion length of the holes due to this current limiting hole transport. Comparing the results of this new technique to that of the Photocarrier Grating method, the electron drift mobility was found to degrade from rm 2.5cm^2/Vs to rm 0.15cm^2/Vs after 6 minutes of 50-Suns degradation.

Yeung, Ping Fai

1995-01-01

29

Thermal/chemical degradation of inorganic membrane materials  

SciTech Connect

The objective of this program is to evaluate the long-term thermal and chemical degradation of inorganic membranes that are developed to separate gases produced by coal combustion and coal gasification. Membrane materials tested include alumina, vycor, platinum foil, and palladium foils. The porosity, permeability, and characterization of physical and chemical changes after exposure to hot gas streams is described.

Krishnan, G.N.; Damle, A.S.; Sanjurjo, A.; Wood, B.J.; Lau, K.H.

1995-12-01

30

DERIVATION OF DAMAGE FUNCTIONS FOR ATMOSPHERIC DEGRADATION OF MATERIALS  

EPA Science Inventory

The information in the pape is directed to those who develop and use damage functions which relate atmospheric degradation of materials to various causal agents in the atmosphere. Such relationships must be quantified mathematically as part of the overall cost-benefit considerati...

31

Thermochemical alkaline degradation of polysaccharide materials: Product characterization and identification  

SciTech Connect

Degradation of cellulosics or starch in alkaline solution produces mostly organic acids which are monocarboxylic in nature. Seven of the organic acids have been identified as formic, acetic, glycolic, lactic, 2-hydroxybutyric, 2-hydroxyisobutyric and 2-hydroxyvaleric acids. In total, their yields amount to 41-46% of starting material weight.

Krochta, J.M.; Hudson, J.S.; Tillin, S.J.; Spala, K.

1985-01-01

32

MATERIALS MANAGEMENT MATERIALS MANAGEMENT -INVENTORY CONTROL  

E-print Network

MATERIALS MANAGEMENT MATERIALS MANAGEMENT - INVENTORY CONTROL NOTICE OF DESIGNATED DEPARTMENTAL MATERIALS COORDINATOR ­ IC-8 Mail, Fax or PDF the entire package to: MC 2010 Fax: 679-4240 REFERENCE # DMC: DEPARTMENTAL MATERIALS COORDINATOR ASSIGNED: CONTACT: TELEPHONE: TITLE: FAX: DIVISION: BUILDING: FLOOR: ROOM

Oliver, Douglas L.

33

Microbial degradation of ignitable liquids on building materials.  

PubMed

Gasoline was added to moldy samples of unused building materials. The unused samples were allowed to sit at room temperature for 2, 4, 7, and 14 days. Each set of samples was extracted using passive headspace concentration and analyzed using gas chromatography-mass spectrometry. Microbial degradation of the gasoline pattern was observed in limited samples to an extent that could result in an inability to identify an ignitable liquid according to ASTM E1618. The degradation noted was largely consistent with the results of previous microbial studies involving soil. PMID:24008200

Hutches, Katherine

2013-10-10

34

Fungal degradation of fiber-reinforced composite materials  

NASA Technical Reports Server (NTRS)

As described in a previous report, a fungal consortium isolated from degraded polymeric materials was capable of growth on presterilized coupons of five composites, resulting in deep penetration into the interior of all materials within five weeks. Data describing the utilization of composite constituents as nutrients for the microflora are described in this article. Increased microbial growth was observed when composite extract was incubated with the fungal inoculum at ambient temperatures. Scanning electron microscopic observation of carbon fibers incubated with a naturally developed population of microorganisms showed the formation of bacterial biofilms on the fiber surfaces, suggesting possible utilization of the fiber chemical sizing as carbon and energy sources. Electrochemical impedance spectroscopy was used to monitor the phenomena occurring at the fiber-matrix interfaces. Significant differences were observed between inoculated and sterile panels of the composite materials. A progressive decline in impedance was detected in the inoculated panels. Several reaction steps may be involved in the degradation process. Initial ingress of water into the resin matrix appeared to be followed by degradation of fiber surfaces, and separation of fibers from the resin matrix. This investigation suggested that composite materials are susceptible to microbial attack by providing nutrients for growth.

Gu, J. D.; Lu, C.; Mitchell, R.; Thorp, K.; Crasto, A.

1997-01-01

35

Gamma-ray-induced degradation of lignocellulosic materials  

SciTech Connect

Lignocellulosic plant materials were treated with various swelling agents and exposed to gamma radiation from 60Co or 137Cs. At dosages of 50 Mrad or above, lignocellulosic materials were extensively degraded and solubilized in water. Addition of water, NaOH, or H2SO4 to the substrate increased the degree of solubilization. Complete solubilization was achieved for samples of sugarcane bagasse, newspaper, cotton linters, cotton cloth, sawdust, and alpha-cellulose powder. About 35% total sugar and 5% reducing sugar per dry weight of sugarcane bagasse could be obtained by this method. Most of the soluble carbohydrates seemed to be disaccharides or larger molecules and glucose degradation products. Solubilization of cellulose was dosage dependent and although the rate of solubilization was increased by adding alkali, released sugar was further decomposed by the alkali and by high dosages of radiation. (Refs. 14).

Han, Y.W.; Timpa, J.; Ciegler, A.; Courtney, J.; Curry, W.F.; Lambremont, E.N.

1981-11-01

36

Storage life of parachutes -- long time material degradation  

Microsoft Academic Search

This study considers the long-time storage of single-use nylon and Kevlar{reg_sign} parachutes. The authors present data from a 29-year-old nylon parachute, and nylon and Kevlar{reg_sign} test samples stored 14 years under ambient conditions in the absence of sunlight. They compare the results with existing predictions of parachute material degradation and other aging data. X-ray photoelectron spectroscopy analyses were preformed on

R. H. Ericksen; L. D. Whinery

1995-01-01

37

Degradation, Fatigue, and Failure of Resin Dental Composite Materials  

Microsoft Academic Search

The intent of this article is to review the numerous factors that affect the mechanical properties of particle-or fiber-filler-containing indirect dental resin composite materials. The focus will be on the effects of degradation due to aging in different media, mainly water and water and ethanol, cyclic loading, and mixed-mode loading on flexure strength and fracture toughness. Several selected papers will

J. L. Drummond

2008-01-01

38

Stress and Damage in Polymer Matrix Composite Materials Due to Material Degradation at High Temperatures  

NASA Technical Reports Server (NTRS)

This report describes analytical methods for calculating stresses and damage caused by degradation of the matrix constituent in polymer matrix composite materials. Laminate geometry, material properties, and matrix degradation states are specified as functions of position and time. Matrix shrinkage and property changes are modeled as functions of the degradation states. The model is incorporated into an existing composite mechanics computer code. Stresses, strains, and deformations at the laminate, ply, and micro levels are calculated, and from these calculations it is determined if there is failure of any kind. The rationale for the model (based on published experimental work) is presented, its integration into the laminate analysis code is outlined, and example results are given, with comparisons to existing material and structural data. The mechanisms behind the changes in properties and in surface cracking during long-term aging of polyimide matrix composites are clarified. High-temperature-material test methods are also evaluated.

McManus, Hugh L.; Chamis, Christos C.

1996-01-01

39

Electrochemical Shock: Mechanical Degradation of Ion-Intercalation Materials  

NASA Astrophysics Data System (ADS)

The ion-intercalation materials used in high-energy batteries such as lithium-ion undergo large composition changes-which correlate to high storage capacity---but which also induce structural changes and stresses that can cause performance metrics such as power, achievable storage capacity, and life to degrade. "Electrochemical shock"---the electrochemical cyclinginduced fracture of materials-contributes to impedance growth and performance degradation in ion-intercalation batteries. Using a combination of micromechanical models and in operando acoustic emission experiments, the mechanisms of electrochemical shock are identified, classified, and modeled in targeted model systems with different composition and microstructure. Three distinct mechanisms of electrochemical shock in ion-intercalation materials are identified: 1) concentration-gradient stresses which arise during fast cycling, 2) two-phase coherency stresses which arise during first-order phase-transformations, and 3) intergranular compatibility stresses in anisotropic polycrystalline materials. While concentration-gradient stresses develop in proportion to the electrochemical cycling rate, two-phase coherency stresses and intergranular compatibility stresses develop independent of the electrochemical cycling rate and persist to arbitrarily low rates. For each mechanism, a micromechanical model with a fracture mechanics failure criterion is developed. This fundamental understanding of electrochemical shock leads naturally to microstructure design criteria and materials selection criteria for ion-intercalation materials with improved life and energy storage efficiency. In a given material system, crystal symmetry and phase-behavior determine the active mechanisms. Layered materials, as exemplified by LiCoO2, are dominated by intergranular compatibility stresses when prepared in polycrystalline form, and two-phase coherency when prepared as single crystal powders. Spinel materials such as LiMn2O4, and LiMn1.5Ni0.5O 4 undergo first-order cubic-to-cubic phasetransformations, and are subject to two-phase coherency stresses even during low-rate electrochemical cycling. This low-rate electrochemical shock is averted in iron-doped material, LiMn 1.5Ni0.42Fe0.08O4, which has continuous solid solubility and is therefore not subject to two-phase coherency stresses; this enables a wider range of particle sizes and duty cycles to be used without electrochemical shock. While lithium-storage materials are used as model systems, the physical phenomena are common to other ion-intercalation systems, including sodium-, magnesium-, and aluminum-storage compounds. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

Woodford, William Henry, IV

40

Novel oxygen atom source for material degradation studies  

NASA Technical Reports Server (NTRS)

Physical Sciences Inc. (PSI) has developed a high flux pulsed source of energetic (8 km/s) atomic oxygen to bombard specimens in experiments on the aging and degradation of materials in a low earth orbit environment. The proof-of-concept of the PSI approach was demonstrated in a Phase 1 effort. In Phase 2 a large O-atom testing device (FAST-2) has been developed and characterized. Quantitative erosion testing of materials, components, and even small assemblies (such as solar cell arrays) can be performed with this source to determine which materials and/or components are most vulnerable to atomic oxygen degradation. The source is conservatively rated to irradiate a 100 sq cm area sample at greater than 10(exp 17) atoms/s, at a 10 Hz pulse rate. Samples can be exposed to an atomic oxygen fluence equivalent to the on-orbit ram direction exposure levels incident on Shuttle surfaces at 250 km during a week-long mission in a few hours.

Krech, R. H.; Caledonia, G. E.

1988-01-01

41

Degradable Hybrid Materials Based on Cationic Acylhydrazone Dynamic Covalent Polymers Promote DNA Complexation through Multivalent Interactions.  

PubMed

The design of smart nonviral vectors for gene delivery is of prime importance for the successful implementation of gene therapies. In particular, degradable analogues of macromolecules represent promising targets as they would combine the multivalent presentation of multiple binding units that is necessary for achieving effective complexation of therapeutic oligonucleotides with the controlled degradation of the vector that would in turn trigger drug release. Toward this end, we have designed and synthesized hybrid polyacylhydrazone-based dynamic materials that combine bis-functionalized cationic monomers with ethylene oxide containing monomers. Polymer formation was characterized by (1) H and DOSY NMR spectroscopy and was found to take place at high concentration, whereas macrocycles were predominantly formed at low concentration. HPLC monitoring of solutions of these materials in aqueous buffers at pH values ranging from 5.0 to 7.0 revealed their acid-catalyzed degradation. An ethidium bromide displacement assay and gel electrophoresis clearly demonstrated that, despite being dynamic, these materials are capable of effectively complexing dsDNA in aqueous buffer and biological serum at N/P ratios comparable to polyethyleneimine polymers. The self-assembly of dynamic covalent polymers through the incorporation of a reversible covalent bond within their main chain is therefore a promising strategy for generating degradable materials that are capable of establishing multivalent interactions and effectively complexing dsDNA in biological media. PMID:25251569

Bouillon, Camille; Paolantoni, Delphine; Rote, Jennifer C; Bessin, Yannick; Peterson, Larryn W; Dumy, Pascal; Ulrich, Sébastien

2014-11-01

42

LDEF (Prelaunch), S1006 : Balloon Material Degradation, Tray E06  

NASA Technical Reports Server (NTRS)

The prelaunch photograph shows the positions of four (4) LDEF experiments in a three (3) inch deep LDEF peripheral tray. The Balloon Materials Degradation Experiment (S1006) experiment is located in the center one third (1/3rd) section, the Multiple Foil Microabrasion Package (MAP) Experiment (AO023) occupies the left one third (1/3rd) section, the Measurement of Heavy Cosmic-Ray Nuclei on LDEF Experiment (M0002-02) is located in the lower one half (1/2) of the right section and the Ion Beam Textured and Coated Surfaces Experiment (S1003) is shown in the top right section of the tray. The Balloon Materials Degradation experiment, located in the center one third (1/3rd) tray section, consist of 38 polymer film specimen, in the form of either thin film or reinforced tape, and 24 fibrous cord specimen. The ends of each test polymer film specimen, approximately 1.0 inch wide and 6.0 inches long, were secured between aluminum clamp strips that attached to aluminum experiment mounting plates. Two specimen of metallized film, aluminized polyester, are mounted on the lower experiment base plate with the reinforced polymer tapes. The cord specimen, approximately 4.0 inches long, are secured along the left and right edges of the experiment mounting plates in a similar manner. Non-magnetic stainless steel fasteners are used for the experiment assembly and for attaching the experiment mounting plate to the tray structure.

1984-01-01

43

Material degradation analysis and maintenance decisions based on material condition monitoring during in-service inspections  

SciTech Connect

The degradation of the material in critical components is shown to be an effective measure which can be used to compute the risk adjusted economic penalty associated with different maintenance decisions. The approach of estimating the probability, with confidence interval, of the time that a prescribed degradation level is exceeded is shown to be practical, as demonstrated in the analysis of irradiated fuel cladding. The methodology for the estimation of the probability is predicated on the existence of a parsimonious and robust mixed-effects model of the evolution of the degradation. This model, in general, relates measured surrogates of the degradation level to computed or measured variables, which characterize the environment during the operating history of the component. We propose and demonstrate the efficacy of using an artificial neural network, constructed via a genetic supervisor, as an aid in developing the requisite mixed-effects model and testing its continued validity as new data are obtained.

Yacout, A.M.; Orechwa, Y.

1996-03-01

44

Computational simulation of coupled material degradation processes for probabilistic lifetime strength of aerospace materials  

NASA Technical Reports Server (NTRS)

The research included ongoing development of methodology that provides probabilistic lifetime strength of aerospace materials via computational simulation. A probabilistic material strength degradation model, in the form of a randomized multifactor interaction equation, is postulated for strength degradation of structural components of aerospace propulsion systems subjected to a number of effects or primative variables. These primative variable may include high temperature, fatigue or creep. In most cases, strength is reduced as a result of the action of a variable. This multifactor interaction strength degradation equation has been randomized and is included in the computer program, PROMISS. Also included in the research is the development of methodology to calibrate the above described constitutive equation using actual experimental materials data together with linear regression of that data, thereby predicting values for the empirical material constraints for each effect or primative variable. This regression methodology is included in the computer program, PROMISC. Actual experimental materials data were obtained from the open literature for materials typically of interest to those studying aerospace propulsion system components. Material data for Inconel 718 was analyzed using the developed methodology.

Boyce, Lola; Bast, Callie C.

1992-01-01

45

Materials with controllable signature properties  

NASA Astrophysics Data System (ADS)

We have in this report considered some types of material with potential for use in signature control of structures. The material types selected for inclusion in this study were electrically conductive polymers, fullerenes, nanostructured materials and Langmuir-Blodgett films. To control the signature of a structure in real time it must be possible to vary the material emissivity, structural transmission, and reflection or absorption of electromagnetic radiation in the relevant wavelength region. This may be achieved by changes in temperature, pressure, electrical or magnetic field or by the concentration of a chemical substance within the material. It is concluded that it is feasible to develop electrically conductive polymeric materials with controllable properties for practical signature control application within 5 to 10 years.

Dickman, O.; Holmberg, B.; Karlsson, T.; Savage, S.

1995-02-01

46

Material Aging and Degradation Detection and Remaining Life Assessment for Plant Life Management  

SciTech Connect

One of the major factors that may impact long term operations is structural material degradation, Detecting materials degradation, estimating the remaining useful life (RUL) of the component, and determining approaches to mitigating the degradation are important from the perspective of long term operations. In this study, multiple nondestructive measurement and monitoring methods were evaluated for their ability to assess the material degradation state. Metrics quantifying the level of damage from these measurements were defined, and evaluated for their ability to provide estimates of remaining life of the component. An example of estimating the RUL from nondestructive measurements of material degradation condition is provided.

Ramuhalli, Pradeep; Henager, Charles H.; Griffin, Jeffrey W.; Meyer, Ryan M.; Coble, Jamie B.; Pitman, Stan G.; Bond, Leonard J.

2012-12-31

47

Common causes of material degradation in buried piping  

SciTech Connect

Buried pipe may fail for innumerable reasons. Causes can be mechanical damage/breakage, chemically initiated corrosion, or a combination. Failures may originate either internally or externally on the pipe. They may be related to flaws in the design, to excessive or unanticipated internal pressure or ground level loading, and/or to poor or uncertain installation practice. Or the pipe may simply ``wear out`` in service. Steel is strong and very forgiving in underground applications, especially with regard to backfill. However, soil support developed through densification or compaction is critical for brittle concrete and vitrified clay tile pipe, and is very important for cast iron and plastic pipe. Chemistry of the soil determines whether or not it will enhance corrosion or other types of degradation. Various causes and mechanisms for deterioration of buried pipe are indicated. Some peculiarities of the different materials of construction are characterized. Repair methods and means to circumvent special problems are described.

Jenkins, C.F.

1997-01-20

48

Degradation study on optical materials for concentrator photovoltaics  

NASA Astrophysics Data System (ADS)

In this work the impact of accelerated aging on the spectral transmission and the mechanical robustness of silicone elastomers for concentrator photovoltaic applications was investigated. Therefore, specific test samples were manufactured. The samples were annealed at 150 °C to assure a complete cross-linking. These samples were exposed to humidity freeze, to a pressure cooker test, and to UV light. To investigate optical materials under UVA intensity up to 10 W/cm2 a test setup was developed. Thus, a UV dosage of 10000 kWh/m2 was applied to the silicone samples after thermal treatment. The mean transmission was used as a measure to identify changes in the spectral behavior and was, therefore, compared after the stress tests with the initial value. No total failures but rather degradation was observed, mainly in the range of ultraviolet and visible light. In addition, the shear strengths for the silicone elastomers were compared before and after stress.

Eltermann, Fabian; Roeder, Kerstin; Wiesenfarth, Maike; Wilde, Juergen; Bett, Andreas W.

2012-10-01

49

Control of Several Emissions during Olive Pomace Thermal Degradation.  

PubMed

Biomass plays an important role as an energy source, being an interesting alternative to fossil fuels due to its environment-friendly and sustainable characteristics. However, due to the exposure of customers to emissions during biomass heating, evolved pollutants should be taken into account and controlled. Changing raw materials or mixing them with another less pollutant biomass could be a suitable step to reduce pollution. This work studied the thermal behaviour of olive pomace, pyrenean oak and their blends under combustion using thermogravimetric analysis. It was possible to monitor the emissions released during the process by coupling mass spectrometry analysis. The experiments were carried out under non-isothermal conditions at the temperature range 25-750 °C and a heating rate of 20 °C·min-1. The following species were analysed: aromatic compounds (benzene and toluene), sulphur emissions (sulphur dioxide), 1,4-dioxin, hydrochloric acid, carbon dioxide and nitrogen oxides. The results indicated that pollutants were mainly evolved in two different stages, which are related to the thermal degradation steps. Thus, depending on the pollutant and raw material composition, different emission profiles were observed. Furthermore, intensity of the emission profiles was related, in some cases, to the composition of the precursor. PMID:25314298

Miranda, Teresa; Nogales, Sergio; Román, Silvia; Montero, Irene; Arranz, José Ignacio; Sepúlveda, Francisco José

2014-01-01

50

Control of Several Emissions during Olive Pomace Thermal Degradation  

PubMed Central

Biomass plays an important role as an energy source, being an interesting alternative to fossil fuels due to its environment-friendly and sustainable characteristics. However, due to the exposure of customers to emissions during biomass heating, evolved pollutants should be taken into account and controlled. Changing raw materials or mixing them with another less pollutant biomass could be a suitable step to reduce pollution. This work studied the thermal behaviour of olive pomace, pyrenean oak and their blends under combustion using thermogravimetric analysis. It was possible to monitor the emissions released during the process by coupling mass spectrometry analysis. The experiments were carried out under non-isothermal conditions at the temperature range 25–750 °C and a heating rate of 20 °C·min?1. The following species were analysed: aromatic compounds (benzene and toluene), sulphur emissions (sulphur dioxide), 1,4-dioxin, hydrochloric acid, carbon dioxide and nitrogen oxides. The results indicated that pollutants were mainly evolved in two different stages, which are related to the thermal degradation steps. Thus, depending on the pollutant and raw material composition, different emission profiles were observed. Furthermore, intensity of the emission profiles was related, in some cases, to the composition of the precursor. PMID:25314298

Miranda, Teresa; Nogales, Sergio; Román, Silvia; Montero, Irene; Arranz, José Ignacio; Sepúlveda, Francisco José

2014-01-01

51

Degradation behavior of Ca-Mg-Zn intermetallic compounds for use as biodegradable implant materials.  

PubMed

With the goal of developing new biodegradable implant materials, we have investigated the degradation behavior of (Ca, Mg)-based intermetallic compounds. The degradation behavior of the compounds within the Ca-Mg-Zn system was roughly classified into four groups, and their behaviors were strongly influenced by the compositions of the compounds. For example, the Ca3MgxZn(15-x) compound exhibited a large solubility region with varying the Mg/Zn ratio, and the Ca3Mg12Zn3 phase alloy with the lowest Zn content was rapidly broken apart within 6h of immersion. Alternatively, the Ca3Mg4.6Zn10.4 phase alloy with the highest Zn content retained the bulk shape even after 250h of immersion. These varying degradation behaviors were ascribed to the difference in the formability of Zn oxide as a protective layer against corrosion on the specimen surfaces, depending on the Zn content. The gained results suggest that there is a feasibility on developing new biodegradable materials based on intermetallic compounds in which the degradation rate can be controlled by their compositions. PMID:25280708

Hagihara, Koji; Shakudo, Shuhei; Fujii, Kenta; Nakano, Takayoshi

2014-11-01

52

Probabilistic analysis for fatigue strength degradation of materials  

NASA Technical Reports Server (NTRS)

This report presents the results of the first year of a research program conducted for NASA-LeRC by the University of Texas at San Antonio. The research included development of methodology that provides a probabilistic treatment of lifetime prediction of structural components of aerospace propulsion systems subjected to fatigue. Material strength degradation models, based on primitive variables, include both a fatigue strength reduction model and a fatigue crack growth model. Linear elastic fracture mechanics is utilized in the latter model. Probabilistic analysis is based on simulation, and both maximum entropy and maximum penalized likelihood methods are used for the generation of probability density functions. The resulting constitutive relationships are included in several computer programs, RANDOM2, RANDOM3, and RANDOM4. These programs determine the random lifetime of an engine component, in mechanical load cycles, to reach a critical fatigue strength or crack size. The material considered was a cast nickel base superalloy, one typical of those used in the Space Shuttle Main Engine.

Royce, Lola

1989-01-01

53

Three-dimensional biomaterial degradation - Material choice, design and extrinsic factor considerations.  

PubMed

The apparent difficulty to precisely control fine-tuning of biomaterial degradation has initiated the recent paradigm shift from conventional top-down fabrication methods to more nature-inspired bottom-up assemblies. Sophistication of material fabrication techniques allows today's scientists to reach beyond conventional natural materials in order to synthesise tomorrow's 'designer material'. Material degradation into smaller components and subsequent release of encapsulated cells or cell-signalling agents have opened medically exploitable avenues, transforming the area of regenerative medicine into a dynamic and self-propagating branch of modern medicine. The aim to synthesise ever more refined scaffolding structures in order to create micro- and nanoenvironments resembling those found in natural tissues now represents an ever growing niche in the materials sciences. Recently, we have developed and conducted the world's first in-human tracheal transplantation using a non-degradable completely synthetic biomaterial. Fuelled by such clinical potential, we are currently developing a biodegradable version suitable for skin tissue engineering and paediatric applications. However, despite enormous efforts, current, as yet insurmountable challenges include precise biomaterial degradation within pre-determined spatial and temporal confines in an effort to release bio-signalling agents in such orchestrated fashion as to fully regenerate functioning tissues. In this review, the authors, almost anti-climactically, ask the readers to step out of the artificially over-constructed spiral of ever more convoluted scaffold fabrication techniques and consider the benefits of controllable bottom-up scaffold fabrication methods. It will further be investigated how scaffold designs and fabrication methods may influence degradation and subsequent release of incorporated elements. A focus will be placed on the delivery of growth factors, stem cells and therapeutic agents alone or in parallel. The difficulties of designing a delivery vehicle capable of delivering multiple factors whilst maintaining distinct release kinetics will be highlighted. Finally, this review will be rounded off with an insight into current literature addressing the recurring issues of degradation product toxicities and suggests means of overcoming those. PMID:24858478

Yildirimer, Lara; Seifalian, Alexander M

2014-01-01

54

Attenuation of landfill leachate by UK Triassic sandstone aquifer materials. 2. Sorption and degradation of organic pollutants in laboratory columns  

NASA Astrophysics Data System (ADS)

The sorption and degradation of dissolved organic matter (DOM) and 13 organic micropollutants (BTEX, aromatic hydrocarbons, chloro-aromatic and -aliphatic compounds, and pesticides) in acetogenic and methanogenic landfill leachate was studied in laboratory columns containing Triassic sandstone aquifer materials from the English Midlands. Solute sorption and degradation relationships were evaluated using a simple transport model. Relative to predictions, micropollutant sorption was decreased up to eightfold in acetogenic leachate, but increased up to sixfold in methanogenic leachate. This behaviour reflects a combination of interactions between the micropollutants, leachate DOM and aquifer mineral fraction. Sorption of DOM was not significant. Degradation of organic fractions occurred under Mn-reducing and SO 4-reducing conditions. Degradation of some micropollutants occurred exclusively under Mn-reducing conditions. DOM and benzene were not significantly degraded under the conditions and time span (up to 280 days) of the experiments. Most micropollutants were degraded immediately or after a lag phase (32-115 days). Micropollutant degradation rates varied considerably (half-lives of 8 to >2000 days) for the same compounds (e.g., TeCE) in different experiments, and for compounds (e.g., naphthalene, DCB and TeCA) within the same experiment. Degradation of many micropollutants was both simultaneous and sequential, and inhibited by the utilisation of different substrates. This mechanism, in combination with lag phases, controls micropollutant degradation potential in these systems more than the degradation rate. These aquifer materials have a potentially large capacity for in situ bioremediation of organic pollutants in landfill leachate and significant degradation may occur in the Mn-reducing zones of leachate plumes. However, degradation of organic pollutants in acetogenic leachate may be limited in aquifers with low pH buffering capacity and reducible Mn oxides. Contaminants in this leachate present a greater risk to groundwater resources in these aquifers than methanogenic leachate.

Thornton, Steven F.; Bright, Mildred I.; Lerner, David N.; Tellam, John H.

2000-05-01

55

Materials Degradation & Failure: Assessment of Structure and Properties. Resources in Technology.  

ERIC Educational Resources Information Center

This module provides information on materials destruction (through corrosion, oxidation, and degradation) and failure. A design brief includes objective, student challenge, resources, student outcomes, and quiz. (SK)

Technology Teacher, 1991

1991-01-01

56

ORNL White Paper on Materials for LWRSP 1 Materials Degradation in Light Water Reactors: Life After 60  

E-print Network

, and an intense neutron field. Degradation of materials in this environment can lead to reduced performance Division Oak Ridge National Laboratory 1. Introduction Nuclear reactors present a very harsh environment of materials is placed in the complex and harsh environment coupled with load, degradation over an extended

Pennycook, Steve

57

Hydrolytically Degradable Hyaluronic Acid Hydrogels with Controlled Temporal Structures  

PubMed Central

Polysaccharides are being processed into biomaterials for numerous biological applications due to their native source in numerous tissues and biological functions. For instance, hyaluronic acid (HA) is found abundantly in the body, interacts with cells through surface receptors, and can regulate cellular behavior (e.g., proliferation, migration). HA was previously modified with reactive groups to form hydrogels that are degraded by hyaluronidases, either added exogenously or produced by cells. However, these hydrogels may be inhibitory and their applications are limited if the appropriate enzymes are not present. Here, for the first time, we synthesized HA macromers and hydrogels that are both hydrolytically (via ester group hydrolysis) and enzymatically degradable. The hydrogel degradation and growth factor release was tailored through the hydrogel cross-linking density (i.e., macromer concentration) and copolymerization with purely enzymatically degradable macromers. When mesenchymal stem cells (MSCs) were encapsulated in the hydrogels, cellular organization and tissue distribution was influenced by the copolymer concentration. Importantly, the distribution of released extracellular matrix molecules (e.g., chondroitin sulfate) was improved with increasing amounts of the hydrolytically degradable component. Overall, this new macromer allows for enhanced control over the structural evolution of the HA hydrogels toward applications as biomaterials. PMID:18324776

Sahoo, Sujata; Chung, Cindy; Khetan, Sudhir; Burdick, Jason A.

2009-01-01

58

Recovery of Material Properties in Service-Degraded Gas Turbine Blades  

Microsoft Academic Search

Gas turbine blades for power generation are generally made of Ni-base superalloys that feature excellent resistance to high temperature and corrosion. Since the blade material properties degrade due to long-term service operation of a gas turbine, the blades need to be replaced periodically. Using service degraded blades, we conducted research on the recovery of the blade material properties. To check

Akihiro ITO; Yukio KAGIYA; Hirotaka WATANABE; Hagime TAKAGI; Daizo SAITO; Yomei YOSHIOKA; Hiroyuki ITO; Junji ISHII

2003-01-01

59

Partially resorbable composite bone plate with controlled degradation rate, desired mechanical properties and bioactivity  

Microsoft Academic Search

Rate of polymer degradation is very important for implantable biomaterials since controlling the degradation rate may complement the biological response and affected mechanical property requirements. In spite of numerous publications on the potential use of combinations of poly lactic acid\\/bioactive glass fillers for degradable bone plate, little information exists on the controlling degradation rate and its effects on the other

A. Zargar Kharazi; M. H. Fathi; F. Bahmani; H. Fanian

2011-01-01

60

Thermal/chemical degradation of inorganic membrane materials  

SciTech Connect

The overall objective of this program is to evaluate the long-term thermal and chemical degradation of inorganic membranes that are being developed to separate gaseous products produced by the gasification or combustion of coal in fixed-, fluidized-, and entrained-bed gasifiers, direct coal-fired turbines, and pressurized-fluidized-bed combustors. Specific objectives of this program are to (1) quantify the extent of the degradation process for the three most detrimental mechanisms by performing laboratory-scale experiments, and (2) develop a predictive model for membrane degradation under operating conditions. At present, no inorganic membranes are commercially available for application in the high-temperature, high-pressure (HTHP) gas environments encountered in integrated gasification combined cycle (IGCC), pressurized fluidized bed combustion (PFBC), and direct coal fired turbine (DCFT) applications. Most of the inorganic membrane development efforts have focused on hydrogen separation membranes which may be used in an IGCC system for maximizing hydrogen production from coal gas or to remove H{sub 2}S and NH{sub 3} contaminants via thermal or catalytic decomposition of these contaminants. The candidate inorganic membranes may be grouped as follows: dense metallic membranes; silica based membranes; alumina based membranes; and carbon based membranes. Results are reported for membrane characterization done so far.

Krishnan, G.N.; Sanjurjo, A.; Damle, A.S.; Wood, B.J.; Lau, K.H.

1994-10-01

61

PIASy controls ubiquitination-dependent proteasomal degradation of Ets-1  

PubMed Central

The ETS transcription factor Ets-1 (E26 transformation-specific-1) plays a critical role in many physiological processes including angiogenesis, haematopoietic development and tumour progression. Its activity can be regulated by post-translational modifications, such as phosphorylation. Recently, we showed that Ets-1 is a target for SUMO (small ubiquitin-like modifier) modification and that PIASy [protein inhibitor of activated STAT (signal transducer and activator of transcription) Y], a specific SUMO-E3 ligase for Ets-1, represses Ets-1-dependent transcription. In the present study, we demonstrated that Ets-1 is degraded by the proteasome and that overexpression of PIASy increased the stability of endogenous and ectopically expressed Ets-1 protein by preventing proteasomal degradation. Moreover, knockdown of the endogenous PIASy expression by RNA interference reduced the protein level of endogenous Ets-1. The proteasome inhibitor MG132 reversed this effect. Deletion analysis showed that the TAD (transcriptional activation domain), which has been identified as the interaction domain with PIASy, was also required for Ets-1 ubiquitination and proteasomal degradation. However, the Ets-1 stabilization by PIASy was not due to reduced ubiquitination of Ets-1. Our results suggested that PIASy controls Ets-1 function, at least in part, by inhibiting Ets-1 protein turnover via the ubiquitin–proteasome system. PMID:17456046

Nishida, Tamotsu; Terashima, Motoko; Fukami, Kiyoko; Yamada, Yoshiji

2007-01-01

62

Degradable thermoresponsive nanogels for protein encapsulation and controlled release.  

PubMed

Reversible addition-fragmentation chain transfer (RAFT) polymerization technique was used for the fabrication of stable core cross-linked micelles (CCL) with thermoresponsive and degradable cores. Well-defined poly(2-methacryloyloxyethyl phosphorylcholine), poly(MPC) macroRAFT agent, was first synthesized with narrow molecular weight distribution via the RAFT process. These CCL micelles (termed as nanogels) with hydrophilic poly(MPC) shell and thermoresponsive core consisting of poly(methoxydiethylene glycol methacrylate) (poly(MeODEGM) and poly(2-aminoethyl methacrylamide hydrochloride) (poly(AEMA) were then obtained in a one-pot process by RAFT polymerization in the presence of an acid degradable cross-linker. These acid degradable nanogels were efficiently synthesized with tunable sizes and low polydispersities. The encapsulation efficiencies of the nanogels with different proteins such as insulin, BSA, and ?-galactosidase were studied and found to be dependent of the cross-linker concentration, size of protein, and the cationic character of the nanogels imparted by the presence of AEMA in the core. The thermoresponsive nature of the synthesized nanogels plays a vital role in protein encapsulation: the hydrophilic core and shell of the nanogels at low temperature allow easy diffusion of the proteins inside out and, with an increase in temperature, the core becomes hydrophobic and the nanogels are easily separated out with entrapped protein. The release profile of insulin from nanogels at low pH was studied and results were analyzed using bicinchoninic assay (BCA). Controlled release of protein was observed over 48 h. PMID:22171688

Bhuchar, Neha; Sunasee, Rajesh; Ishihara, Kazuhiko; Thundat, Thomas; Narain, Ravin

2012-01-18

63

Sources of high temperature degradation of cement-based materials : nanoindentation and microporoelastic analysis  

E-print Network

The effects of high temperature exposure on cement-based materials have been under investigation for quite some time, but a fundamental understanding of the sources of high temperature degradation has been limited by ...

DeJong, Matthew J. (Matthew Justin)

2005-01-01

64

Control of in vivo mineral bone cement degradation.  

PubMed

The current study aimed to prevent the formation of hydroxyapatite reprecipitates in brushite-forming biocements by minimizing the availability of free Ca(2+) ions in the cement matrix. This was achieved by both maximizing the degree of cement setting to avoid unreacted, calcium-rich cement raw materials which can deliver Ca(2+) directly to the cement matrix after dissolution, and by a reduction in porosity to reduce Ca(2+) diffusion into the set cement matrix. In addition, a biocement based on the formation of the magnesium phosphate mineral struvite (MgNH4PO4·6H2O) was tested, which should prevent the formation of low-solubility hydroxyapatite reprecipitates due to the high magnesium content. Different porosity levels were fabricated by altering the powder-to-liquid ratio at which the cements were mixed and the materials were implanted into mechanically unloaded femoral defects in sheep for up to 10 months. While the higher-porosity brushite cement quantitatively transformed into crystalline octacalcium phosphate after 10 months, slowing down cement resorption, a lower-porosity brushite cement modification was found to be chemically stable with the absence of reprecipitate formation and minor cement resorption from the implant surface. In contrast, struvite-forming cements were much more degradable due to the absence of mineral reprecipitates and a nearly quantitative cement degradation was found after 10 months of implantation. PMID:24769112

Kanter, Britta; Geffers, Martha; Ignatius, Anita; Gbureck, Uwe

2014-07-01

65

Advanced Materials for RSOFC Dual Operation with Low Degradation  

SciTech Connect

Reversible solid oxide fuel cells (RSOFCs) are energy conversion devices. They are capable of operating in both power generation mode (SOFC) and electrolysis modes (SOEC). RSOFC can integrate renewable production of electricity and hydrogen when power generation and steam electrolysis are coupled in a system, which can turn intermittent solar and wind energy into "firm power." In this DOE EERE project, VPS continuously advanced RSOFC cell stack technology in the areas of endurance and performance. Over 20 types of RSOFC cells were developed in the project. Many of those exceeded performance (area specific resistance less than 300 mohmcm2) and endurance (degradation rate less than 4% per 1000 hours) targets in both fuel cell and electrolysis modes at 750C. One of those cells, RSOFC-7, further demonstrated the following: Steady-state electrolysis with a degradation rate of 1.5% per 1000 hours. Ultra high current electrolysis over 3 A/cm2 at 75% water electrolysis efficiency voltage of 1.67 V. Daily SOFC/SOEC cyclic test of over 600 days with a degradation rate of 1.5% per 1000 hours. Over 6000 SOFC/SOEC cycles in an accelerated 20-minute cycling with degradation less than 3% per 1000 cycles. In RSOFC stack development, a number of kW-class RSOFC stacks were developed and demonstrated the following: Steady-state electrolysis operation of over 5000 hours. Daily SOFC/SOEC cyclic test of 100 cycles. Scale up capability of using large area cells with 550 cm2 active area showing the potential for large-scale RSOFC stack development in the future. Although this project is an open-ended development project, this effort, leveraging Versa Power Systems' years of development experience, has the potential to bring renewable energy RSOFC storage systems significantly closer to commercial viability through improvements in RSOFC durability, performance, and cost. When unitized and deployed in renewable solar and wind installations, an RSOFC system can enable higher availability for intermittent renewable resources, thereby improving the commercial viability of these types of energy resources.

Eric, Tang; Tony, Wood; Sofiane, Benhaddad; Casey, Brown; Hongpeng, He; Jeff, Nelson; Oliver, Grande; Ben, Nuttall; Mark, Richards; Randy, Petri

2012-12-27

66

Probabilistic constitutive relationships for material strength degradation models  

NASA Technical Reports Server (NTRS)

In the present probabilistic methodology for the strength of aerospace propulsion system structural components subjected to such environmentally-induced primitive variables as loading stresses, high temperature, chemical corrosion, and radiation, time is encompassed as an interacting element, allowing the projection of creep and fatigue effects. A probabilistic constitutive equation is postulated to account for the degradation of strength due to these primitive variables which may be calibrated by an appropriately curve-fitted least-squares multiple regression of experimental data. The resulting probabilistic constitutive equation is embodied in the PROMISS code for aerospace propulsion component random strength determination.

Boyce, L.; Chamis, C. C.

1989-01-01

67

New Evaluation Method of Material Degradation Considering Synergistic Effects of Radiation Damage  

Microsoft Academic Search

In core structural materials of next generation reactors such as a liquid-metal cooled fast breeding reactor and a supercritical-water cooled thermal or first reactor, materials' degradation behavior by neutron irradiation damage and thermal (cyclic) stress should be considered with fair accuracy in design process (including maintenance and repair plans), because the materials are used under higher temperature gradients and higher

Yukio Miwa; Yoshiyuki Kaji; Nariaki Okubo; Keietsu Kondo; Takashi Tsukada

2008-01-01

68

Photoconversion of gasified organic materials into biologically-degradable plastics  

DOEpatents

A process is described for converting organic materials (such as biomass wastes) into a bioplastic suitable for use as a biodegradable plastic. In a preferred embodiment the process involves thermally gasifying the organic material into primarily carbon monoxide and hydrogen, followed by photosynthetic bacterial assimilation of the gases into cell material. The process is ideally suited for waste recycling and for production of useful biodegradable plastic polymer. 3 figures.

Weaver, P.F.; Pinching Maness.

1993-10-05

69

Photoconversion of gasified organic materials into biologically-degradable plastics  

DOEpatents

A process is described for converting organic materials (such as biomass wastes) into a bioplastic suitable for use as a biodegradable plastic. In a preferred embodiment the process involves thermally gasifying the organic material into primarily carbon monoxide and hydrogen, followed by photosynthetic bacterial assimilation of the gases into cell material. The process is ideally suited for waste recycling and for production of useful biodegradable plastic polymer.

Weaver, Paul F. (Golden, CO); Maness, Pin-Ching (Golden, CO)

1993-01-01

70

Controllably degradable ?-sheet nanofibers and gels from self-assembling depsipeptides  

PubMed Central

Self-assembled peptide materials have received considerable interest for a range of applications, including 3D cell culture, tissue engineering, and the delivery of cells and drugs. One challenge in applying such materials within these areas has been the extreme stability of ?-sheet fibrillized peptides, which are resistant to proteolysis, degradation, and turnover in biological environments. In this study, we designed self-assembling depsipeptides containing ester bonds within the peptide backbone. Beta-sheet fibrillized nanofibers were formed in physiologic conditions, and two of these nanofiber-forming depsipeptides produced hydrogels that degraded controllably over the course of days-to-weeks via ester hydrolysis. With HPLC, TEM, and oscillating rheometry, we show that the rate of hydrolysis can be controlled in a straightforward manner by specifying the amino acid residues surrounding the ester bond. In 3D cell cultures, depsipeptide gels softened over the course of several days and permitted considerably more proliferation and spreading of C3H10T1/2 pluripotent stem cells than non-degradable analogs. This approach now provides a reliable and reproducible means to soften or clear ?-sheet fibrillized peptide materials from biological environments. PMID:24224082

Tian, Ye F.; Hudalla, Gregory A.; Han, Huifang; Collier, Joel H.

2013-01-01

71

Long-Term Lunar Radiation Degradation Effects on Materials  

NASA Technical Reports Server (NTRS)

The National Aeronautics and Space Administration (NASA) is focused on developing technologies for extending human presence beyond low Earth orbit. These technologies are to advance the state-of-the-art and provide for longer duration missions outside the protection of Earth's magnetosphere. One technology of great interest for large structures is advanced composite materials, due to their weight and cost savings, enhanced radiation protection for the crew, and potential for performance improvements when compared with existing metals. However, these materials have not been characterized for the interplanetary space environment, and particularly the effects of high energy radiation, which is known to cause damage to polymeric materials. Therefore, a study focusing on a lunar habitation element was undertaken to investigate the integrity of potential structural composite materials after exposure to a long-term lunar radiation environment. An overview of the study results are presented, along with a discussion of recommended future work.

Rojdev, Kristina; ORourke, Mary Jane; Koontz, Steve; Alred, John; Hill, Charles; Devivar, Rodrigo; Morera-Felix, Shakira; Atwell, William; Nutt, Steve; Sabbann, Leslie

2010-01-01

72

Electrochemical shock : mechanical degradation of ion-intercalation materials  

E-print Network

The ion-intercalation materials used in high-energy batteries such as lithium-ion undergo large composition changes-which correlate to high storage capacity-but which also induce structural changes and stresses that can ...

Woodford, William Henry, IV

2013-01-01

73

A novel method for on-orbit measurement of space materials degradation  

SciTech Connect

The low Earth orbit (LEO) environment is considered hazardous to spacecraft, resulting in materials degradation. Currently, in order to evaluate the degradation of materials in LEO, a retrieval of space exposed samples is required. In this study, a novel approach is proposed to evaluate degradation of materials in LEO without the need of retrieval. The method is utilizing photovoltaic cells (PVCs), an existing component onboard of any satellite. The PVCs are coated by various materials which are sensitive to different LEO constituents, such as atomic oxygen (AO) or ultra-violet (UV) radiation. The method's acronym is ORMADD (on-ORbit MAterials Degradation Detector). The ORMADD's principle of operation is based on measuring the PVC output power which depends on the cell coating material's optical transmission. Erosion of the coating by AO or coloring due to UV radiation affects its optical transmission and, accordingly, the PVC output. The ORMADD performance was tested using different coatings, such as polyimide and amorphous carbon (sensitive to AO), and siloxane based coating which is sensitive to UV radiation. The proposed ORMADD reveals sensitivity to different LEO components and can be used either as material degradation detector or as an AO monitor.

Verker, Ronen; Grossman, Eitan; Gouzman, Irina [Space Environment Department, Soreq NRC, Yavne 81800 (Israel)

2011-02-15

74

Networked control systems by PID controller Improvement of performance degradation caused by packet loss  

Microsoft Academic Search

This study was performed to examine the performance of networked control systems (NCSs) with a PID controller. Here, we discuss packet loss, especially improvement of the response degradation caused by manipulated variable (MV) packet loss. With MV packet loss, the actuator complements MV by inputting some value to the plant. This complemented value is different from the MV calculated by

Ryotaro OKANO; T. Ohtani; A. Nagashima

2008-01-01

75

Understanding and harnessing energy-dependent proteolysis for controlled protein degradation in bacteria  

E-print Network

Regulated intracellular protein degradation is critical for cellular viability. In many organisms, degradation controls cell-cycle progression, executes responses to stress-inducing environmental changes, and enables the ...

Davis, Joseph H. (Joseph Harry), III

2010-01-01

76

Caveolin: a possible biomarker of degradable metallic materials toxicity in vascular cells.  

PubMed

Iron-based materials could constitute an interesting option for cardiovascular biodegradable stent applications due to their appropriate ductility compared with their counterparts, magnesium alloys. However, the predicted degradation rate of pure iron is considered to be too slow for such applications. We explored manganese (35 wt.%) as an alloying element in combination with iron to circumvent this problem through powder metallurgical processing (Fe-35Mn). Manganese, on the other hand, is highly cytotoxic. We recently explored a new method to better characterize the safety of degradable metallic materials (DMMs) by establishing the gene expression profile (GEP) of cells (mouse 3T3 fibroblasts) exposed to Fe-35Mn degradation products in order to better understand their global response to a potentially cytotoxic DMM. We identified a number of up- and down-regulated genes and confirmed the regulation of a subset of them by quantitative real time polymerase chain reaction. Caveolin-1 (cav1), the structural protein of caveolae, small, smooth plasma membrane invaginations present in various differentiated cell types, was one of the most down-regulated genes in our GEPs. In the present study we further studied the potential of this 22 kDa protein to become a biomarker for cytotoxicity after exposure to degradable metallic elements. In order to better characterize cav1 expression in this context 3T3 mouse fibroblasts were exposed to either ferrous and manganese ions at cytostatic concentrations for 24 or 48 h. cav1 gene expression was not influenced by exposure to ferrous ions. On the other hand, exposure to manganese for 24h reduced cav1 gene expression by about 30% and by >65% after 48 h compared with control 3T3 cells. The cav1 cellular protein content was reduced to the same extent. The same pattern of expression of cav3 (the muscle-specific caveolin subtype) was also observed in this study. This strong and reproducible pattern of regulation of caveolins thus indicates potential as a biomarker for the toxicity of DMM elements. PMID:23597857

Purnama, Agung; Mantovani, Diego; Couet, Jacques

2013-11-01

77

ADAPTIVE OPTICS CONTROL FOR LASER MATERIAL PROCESSING  

E-print Network

ADAPTIVE OPTICS CONTROL FOR LASER MATERIAL PROCESSING S. Mauch , J. Reger , E. Beckert Control-mail: erik.beckert@iof.fraunhofer.de) Abstract: An adaptive optics system is used for correcting tip: adaptive optics, tip-tilt control, Kalman-filtering, material processing 1. INTRODUCTION In laser material

Knobloch,Jürgen

78

Degradation mechanisms of nylon separator materials for a nickel-cadmium cell in KOH electrolytes  

Microsoft Academic Search

Degradation reactions of a nylon-6 battery separator material have been studied in 4-34-percent aqueous KOH electrolytes at 35-110 C. In a Ni\\/Cd cell, this degradation involves a slow hydrolysis reaction followed by fast electrochemical oxidations of the hydrolysis reaction products. Arrhenius activation energy of the hydrolysis reaction in 34-percent KOH was 20.0 + or - 0.3 kcal\\/mole. A plot of

H. S. Lim; J. D. Margerum; S. A. Verzwyvelt; A. M. Lackner; R. C. Knechtli

1989-01-01

79

Degradation mechanisms of nylon separator materials for a nickel-cadmium cell in KOH electrolytes  

Microsoft Academic Search

Degradation reactions of a nylon 6 battery separator material have been studied in 4-34% aqueous KOH electrolytes at 35°⁻¹¹°sup 0\\/C. In a Ni\\/Cd cell, this degradation involves a slow hydrolysis reaction followed by fast electrochemical oxidations of the hydrolysis reaction products. Arrhenius activation energy of the hydrolysis reaction in 34% KOH was 20.0 +- 0.3 kcal\\/mole. A plot of the

H. S. Lim; J. D. Margerum; S. A. Verzwyvelt; A. M. Lackner; R. C. Knechtli

1989-01-01

80

Condition monitoring methods applied to degradation of chlorosulfonated polyethylene cable jacketing materials.  

SciTech Connect

Three promising polymer material condition monitoring (CM) methods were applied to eight commercial chlorosulfonated polyethylene cable jacket materials aged under both elevated temperature and high-energy radiation conditions. The CM methods examined, cross-sectional modulus profiling, solvent uptake and NMR T{sub 2} relaxation time measurements of solvent-swelled samples, are closely related since they are all strongly influenced by the changes in overall crosslink density of the materials. Each approach was found to correlate well with ultimate tensile elongation measurements, the most widely used method for following degradation of elastomeric materials. In addition approximately universal failure criteria were found to be applicable for the modulus profiling and solvent uptake measurements, independent of the CSPE material examined and its degradation environment. For an arbitrarily assumed elongation 'failure' criterion of 50% absolute, the CSPE materials typically reached 'failure' when the modulus increased to {approx}35 MPa and the uptake factor in p-xylene decreased to {approx}1.6.

Assink, Roger Alan; Gillen, Kenneth Todd; Bernstein, Robert; Celina, Mathias Christopher

2005-05-01

81

New Evaluation Method of Material Degradation Considering Synergistic Effects of Radiation Damage  

NASA Astrophysics Data System (ADS)

In core structural materials of next generation reactors such as a liquid-metal cooled fast breeding reactor and a supercritical-water cooled thermal or first reactor, materials' degradation behavior by neutron irradiation damage and thermal (cyclic) stress should be considered with fair accuracy in design process (including maintenance and repair plans), because the materials are used under higher temperature gradients and higher neutron flux fields than those in the present light water reactors. In the current experiential design rules, service lives of core structural components were determined by the materials degradation such as the increase of ductile-to-brittle transition temperature after post irradiation examination data. However, other materials degradations such as irradiation-assisted stress corrosion cracking (IASCC), which occurs by the degradation synergistically interacting with radiation hardening, local chemical composition change, swelling and radiation creep, should be considered reasonably in the design process of the next generation reactors, because of the anticipation of the beneficial effects by synergy of radiation damage. The radiation hardening and local chemical composition change at grain boundaries due to radiation-induced segregation increased with increasing dose. Above some threshold dose, swelling increased rapidly with increasing dose. Residual stress due to thermal stress and welding procedure decreased with increasing dose. To predict material failure by IASCC with reasonable accuracy, in this study, each material degradation phenomenon with different dose dependence was modeled with consideration of radiation induced stress relaxation. And then the models were integrated to simulate the failure behavior for the duration of reactor operation period. In this paper, the models obtained by ion-irradiation experiments and compared by data from neutron irradiation experiments were presented, and the concept of our new evaluation method and the programming code for the failure simulation were outlined.

Miwa, Yukio; Kaji, Yoshiyuki; Okubo, Nariaki; Kondo, Keietsu; Tsukada, Takashi

82

Degradation modes of nickel-base alternate waste package overpack materials  

SciTech Connect

The suitability of Ti Grade 12 for waste package overpacks has been questioned because of its observed susceptibility to crevice corrosion and hydrogen-assisted crack growth. For this reason, materials have been selected for evaluation as alternatives to Ti Grade 12 for use as waste package overpacks. These alternative materials, which are based on the nickel-chromium-molybdenum (Ni-Cr-Mo) alloy system, are Inconel 625, Hastelloy C-276, and Hastelloy C-22. The degradation modes of the Ni-base alternate materials have been examined at Pacific Northwest Laboratory to determine the suitability of these materials for waste package overpack applications in a salt repository. Degradation modes investigated included general corrosion, crevice corrosion, pitting, stress-corrosion cracking, and hydrogen embrittlement.

Pitman, S.G.

1988-07-01

83

Materials Chemistry and Physics 100 (2006) 3840 X-ray irradiation induced degradation of cellulose nitrate  

E-print Network

nitrate F.M.F. Ng, K.N. Yu Department of Physics and Materials Science, City University of Hong Kong, Tat the thickness of the cellulose nitrate layer of the commonly used LR 115 solid-state nuclear track detector spectrometry will induce degradation of the cellulose nitrate. For this purpose, Fourier transform infrared

Yu, K.N.

84

7—THE PROGRESSIVE DETERIORATION OF TEXTILE MATERIALS PART I: CHARACTERISTICS OF DEGRADATION  

Microsoft Academic Search

Textile materials deteriorate, during their useful life, by being subjected to the effects of many degradative mechanisms. Sunlight, weathering, laundering or dry-cleaning treatments, abrasion, perspiration, and other such unavoidable sources of fibre damage all exert their toll on physical or chemical properties to cause changes that can limit useful fabric life.Physical changes may occur in the dimensions, tensile, tearing, or

K. Slater

1986-01-01

85

Small-Molecule Control of Protein Degradation Using Split Adaptors  

E-print Network

Targeted intracellular degradation provides a method to study the biological function of proteins and has numerous applications in biotechnology. One promising approach uses adaptor proteins to target substrates with ...

Davis, Joseph H.

86

Evaluation of commutability of control materials.  

PubMed

The commutability of 13 control materials was evaluated by performing parallel measurements on two different analysers: a Synchron CX-5 Delta from Beckman-Coulter and a Vitros 950 from Ortho-Clinical Diagnostics. Twenty three clinical chemistry analytes (substrates, electrolytes and enzymatic activities) were determined in plasma from 15 different patients in order to define intermethod relationship for each analyte. The relationship observed for each control material was compared to those obtained for patients' specimens. The results show that commutability depends both on the tested analyte and on the control material. No totally commutable material has been found for the whole set of tested parameters. Most control materials were commutable for inorganic phosphate, glucose, chloride, triglycerides, alanine aminotransferase, amylase and y-glutamyltransfera-se, but less than a quarter of control materials were commutable for sodium, calcium, creatinine, alkaline phosphatase and lipase. Seven materials were commutable for more than half of the analytes, whereas five control materials were commutable for less than a quarter of these analytes. We propose to verify the commutability of materials before their use in an external quality control assessement. PMID:12211660

Brion, Emmanuel; Lessinger, Jean-Marc; Gould, Nicholas; Leyendecker, Jacky; Férard, Georges

2002-06-01

87

Carbon Nanotube Materials for Substrate Enhanced Control of Catalytic Activity  

SciTech Connect

Carbon SWNTs are attractive materials for supporting electrocatalysts. The properties of SWNTs are highly tunable and controlled by the nanotube's circumferential periodicity and their surface chemistry. These unique characteristics suggest that architectures constructed from these types of carbon support materials would exhibit interesting and useful properties. Here, we expect that the structure of the carbon nanotube support will play a major role in stabilizing metal electrocatalysts under extreme operating conditions and suppress both catalyst and support degradation. Furthermore, the chemical modification of the carbon nanotube surfaces can be expected to alter the interface between the catalyst and support, thus, enhancing the activity and utilization of the electrocatalysts. We plan to incorporate discrete reaction sites into the carbon nanotube lattice to create intimate electrical contacts with the catalyst particles to increase the metal catalyst activity and utilization. The work involves materials synthesis, design of electrode architectures on the nanoscale, control of the electronic, ionic, and mass fluxes, and use of advanced optical spectroscopy techniques.

Heben, M.; Dillon, A. C.; Engtrakul, C.; Lee, S.-H.; Kelley, R. D.; Kini, A. M.

2007-05-01

88

Thermal/chemical degradation of ceramic cross-flow filter materials  

SciTech Connect

This report summarizes the 14-month, Phase 1 effort conducted by Westinghouse on the Thermal/Chemical Degradation of Ceramic Cross-Flow Filter Materials program. In Phase 1 expected filter process conditions were identified for a fixed-bed, fluid-bed, and entrained-bed gasification, direct coal fired turbine, and pressurized fluidized-bed combustion system. Ceramic cross-flow filter materials were also selected, procured, and subjected to chemical and physical characterization. The stability of each of the ceramic cross-flow materials was assessed in terms of potential reactions or phase change as a result of process temperature, and effluent gas compositions containing alkali and fines. In addition chemical and physical characterization was conducted on cross-flow filters that were exposed to the METC fluid-bed gasifier and the New York University pressurized fluidized-bed combustor. Long-term high temperature degradation mechanisms were proposed for each ceramic cross-flow material at process operating conditions. An experimental bench-scale test program is recommended to be conducted in Phase 2, generating data that support the proposed cross-flow filter material thermal/chemical degradation mechanisms. Papers on the individual subtasks have been processed separately for inclusion on the data base.

Alvin, M.A.; Lane, J.E.; Lippert, T.E.

1989-11-01

89

Semi-degradable poly(?-amino ester) networks with temporally controlled enhancement of mechanical properties.  

PubMed

Biodegradable polymers are clinically used in numerous biomedical applications, and classically show a loss of mechanical properties within weeks of implantation. This work demonstrates a new class of semi-degradable polymers that show an increase in mechanical properties through degradation via a controlled shift in a thermal transition. Semi-degradable polymer networks, poly(?-amino ester)-co-methyl methacrylate, were formed from a low glass transition temperature crosslinker, poly(?-amino ester), and high glass transition temperature monomer, methyl methacrylate, which degraded in a manner dependent upon the crosslinker chemical structure. In vitro and in vivo degradation revealed changes in mechanical behavior due to the degradation of the crosslinker from the polymer network. This novel polymer system demonstrates a strategy to temporally control the mechanical behavior of polymers and to enhance the initial performance of smart biomedical devices. PMID:24769113

Safranski, David L; Weiss, Daiana; Clark, J Brian; Taylor, W Robert; Gall, Ken

2014-08-01

90

Satellite spacecraft charging control materials  

NASA Astrophysics Data System (ADS)

The feasibility of conductive adhesive techniques for the electrical interconnection of ITO-coated second surface mirrors has been studied. The good electrostatic performance and the durability of components combining ITO coated aluminized Kapton and aluminum straps by means of a silver loaded silicone have been confirmed by a prequalification program. The charge dissipation mechanisms for silica fabrics in a geosynchronous magnetic substorm environment have been studied by means of various sample configurations that have been tested under electron beam. Some recommendations have been given for a better use of silica fabrics as thermal control coatings in space.

Benaissa, B.; Levy, L.; Paillous, A.; Sarrail, D.

1980-04-01

91

Emergency Scenarios of a Re-Entry Vehicle due to Control Degradation  

Microsoft Academic Search

A controls degradation scenario is investigated for a reentry vehicle. It is assumed that one of two body flaps is blocked. The reaction control system is used to generate control moments in combination with the aerodynamic surfaces still operative. Particular emphasis is placed on implementing a control allocation method which yields an optimum utilization of the aerodynamic control surfaces in

O. da Costa; G. Sachs

2004-01-01

92

Measurement control administration for nuclear materials accountability.  

National Technical Information Service (NTIS)

In 1986 a measurement control program was instituted at Mound to ensure that measurement performance used for nuclear material accountability was properly monitored and documented. The organization and management of various aspects of the program are disc...

C. R. Rudy

1991-01-01

93

High-Resolution Crack Imaging Reveals Degradation Processes in Nuclear Reactor Structural Materials  

SciTech Connect

Corrosion and cracking represent critical failure mechanisms for structural materials in many applications. Although a crack can often be seen with the unaided eye, higher resolution imaging techniques are required to understand the nature of the crack tips and underlying degradation processes. Researchers at Pacific Northwest National Laboratory (PNNL) employ a suite of microscopy techniques and site-specific material sampling to analyze corrosion and crack structures, producing images and compositional analyses with near-atomic spatial resolution. The samples are cracked components removed from commercial light-water reactor service or laboratory samples tested in simulated reactor environments.

Olszta, Matthew J.; Schreiber, Daniel K.; Thomas, Larry E.; Bruemmer, Stephen M.

2012-04-01

94

Water-Soluble, Biocompatible Polyphosphazenes with Controllable and pH-Promoted Degradation Behavior  

PubMed Central

The synthesis of a series of novel, water-soluble poly(organophosphazenes) prepared via living cationic polymerization is presented. The degradation profiles of the polyphosphazenes prepared are analyzed by GPC, 31P NMR spectroscopy, and UV–Vis spectroscopy in aqueous media and show tunable degradation rates ranging from days to months, adjusted by subtle changes to the chemical structure of the polyphosphazene. Furthermore, it is observed that these polymers demonstrate a pH-promoted hydrolytic degradation behavior, with a remarkably faster rate of degradation at lower pH values. These degradable, water soluble polymers with controlled molecular weights and structures could be of significant interest for use in aqueous biomedical applications, such as polymer therapeutics, in which biological clearance is a requirement and in this context cell viability tests are described which show the non-toxic nature of the polymers as well as their degradation intermediates and products. PMID:24729657

Wilfert, Sandra; Iturmendi, Aitziber; Schoefberger, Wolfgang; Kryeziu, Kushtrim; Heffeter, Petra; Berger, Walter; Bruggemann, Oliver; Teasdale, Ian

2014-01-01

95

Comparison of amorphous silicon absorber materials: Light-induced degradation and solar cell efficiency  

NASA Astrophysics Data System (ADS)

Several amorphous silicon (a-Si:H) deposition conditions have been reported to produce films that degrade least under light soaking when incorporated into a-Si:H solar cells. However, a systematic comparison of these a-Si:H materials has never been presented. In the present study, different plasma-enhanced chemical vapor deposition conditions, yielding standard low-pressure VHF a-Si:H, protocrystalline, polymorphous, and high-pressure RF a-Si:H materials, are compared with respect to their optical properties and their behavior when incorporated into single-junction solar cells. A wide deposition parameter space has been explored in the same deposition system varying hydrogen dilution, deposition pressure, temperature, frequency, and power. From the physics of layer growth, to layer properties, to solar cell performance and light-induced degradation, a consistent picture of a-Si:H materials that are currently used for a-Si:H solar cells emerges. The applications of these materials in single-junction, tandem, and triple-junction solar cells are discussed, as well as their deposition compatibility with rough substrates, taking into account aspects of voltage, current, and charge collection. In sum, this contributes to answering the question, "Which material is best for which type of solar cell?"

Stuckelberger, M.; Despeisse, M.; Bugnon, G.; Schüttauf, J.-W.; Haug, F.-J.; Ballif, C.

2013-10-01

96

Characterization of material degradation in ceramic matrix composites using infrared reflectance spectroscopy  

SciTech Connect

Ceramic matrix composite materials for thermal protection systems are required to maintain operational performance in extreme thermal and mechanical environments. In-service inspection of materials capable of assessing the degree and extent of damage and degradation will be required to ensure the safety and readiness of future air vehicles. Infrared reflectance spectroscopy is an established material characterization technique capable of extracting information regarding the chemical composition of substances. The viability of this technique as a potentially powerful nondestructive evaluation method capable of monitoring degradation in thermal protection system materials subjected to extreme mechanical and thermal environments is analyzed. Several oxide-based and non-oxide-based ceramic matrix composite materials were stressed to failure in a high temperature environment and subsequently measured using infrared reflectance spectroscopy. Spectral signatures at locations along the length of the samples were compared resulting in distinct and monotonic reflectance peak changes while approaching the fracture point. The chemical significance of the observed signatures and the feasibility of infrared reflectance nondestructive evaluation techniques are discussed.

Cooney, Adam T.; Flattum-Riemers, Richard Y. [Air Force Research Laboratory, Materials and Manufacturing Directorate, NonDestructive Evaluation Branch, Wright-Patterson AFB, OH (United States); Scott, Benjamin J. [Universal Technology Corporation, Dayton, OH (United States)

2011-06-23

97

Degradation mechanisms of cable insulation materials during radiation-thermal ageing in radiation environment  

NASA Astrophysics Data System (ADS)

Radiation and thermal degradation of ethylene-propylene rubber (EPR) and crosslinked polyethylene (XLPE) as cable insulation materials were investigated by evaluating tensile properties, gel-fraction, and swelling ratio, as well as by the infrared (FTIR) analysis. The activation energy of thermal oxidative degradation changed over the range 100-120 °C for both EPR and XLPE. This may be attributed to the fact that the content of an antioxidant used as the stabilizer for polymers decreases by evaporation during thermal ageing at high temperatures. The analysis of antioxidant content and oxidative products in XLPE as a model sample showed that a small amount of antioxidant significantly reduced the extent of thermal oxidation, but was not effective for radiation induced oxidation. The changes in mechanical properties were well reflected by the degree of oxidation. A new model of polymer degradation mechanisms was proposed where the degradation does not take place by chain reaction via peroxy radical and hydro-peroxide. The role of the antioxidant in the polymer is the reduction of free radical formation in the initiation step in thermal oxidation, and it could not stop radical reactions for either radiation or thermal oxidation.

Seguchi, Tadao; Tamura, Kiyotoshi; Ohshima, Takeshi; Shimada, Akihiko; Kudoh, Hisaaki

2011-02-01

98

Posttranscriptional control of gene expression: bacterial mRNA degradation  

Microsoft Academic Search

Many biological processes cannot be fully understood without detailed knowledge of RNA metabolism. The continuous breakdown and resynthesis of prokaryotic mRNA permit rapid production of new kinds of proteins. In this way, mRNA levels can regulate protein synthesis and cellular growth. Analysing mRNA degradation in prokaryotes has been particularly difficult because most mRNA undergo rapid exponential decay. Prokaryotic mRNAs differ

C. M. Arraiano

1993-01-01

99

Rapid materials degradation induced by surfaces and voids: ab initio modeling of ?-octatetramethylene [corrected] tetranitramine.  

PubMed

A computational strategy based on coupling density functional theory, variational transition state theory, and a microscale materials morphology description unravels details of the defect-induced effect on the surface decomposition of molecular crystals. The technique allows us to resolve the earliest stages of decomposing solids, even for very complex materials and for ultrafast chemical reactions. A comparative analysis of chemical decomposition reactions in HMX with progressively increasing system complexity (an isolated HMX molecule; a perfect single HMX crystal; a defect-containing, porous, and granular HMX crystal) demonstrates that the initiation of the material's degradation can be effectively manipulated by changing the crystal morphology. The activation barriers, reaction constants, and corresponding reaction rates are obtained as a function of molecular environment (a molecule in a vacuum, in an ideal bulk crystal, on a surface or interface, and on a defect in a solid), and decomposition times are predicted. The computational approach can be applied to any other material and system. PMID:22703290

Sharia, Onise; Kuklja, Maija M

2012-07-18

100

Downhole material injector for lost circulation control  

DOEpatents

Apparatus and method are disclosed for simultaneously and separately emplacing two streams of different materials through a drill string in a borehole to a downhole location for lost circulation control. The two streams are mixed outside the drill string at the desired downhole location and harden only after mixing for control of a lost circulation zone. 6 figs.

Glowka, D.A.

1994-09-06

101

Downhole material injector for lost circulation control  

DOEpatents

Apparatus and method for simultaneously and separately emplacing two streams of different materials through a drillstring in a borehole to a downhole location for lost circulation control. The two streams are mixed outside the drillstring at the desired downhole location and harden only after mixing for control of a lost circulation zone.

Glowka, David A. (Tijeras, NM)

1994-01-01

102

Downhole material injector for lost circulation control  

DOEpatents

This invention is comprised of an apparatus and method for simultaneously and separately emplacing two streams of different materials through a drillstring in a borehole to a downhole location for lost circulation control. The two streams are mixed outside the drillstring at the desired downhole location and harden only after mixing for control of a lost circulation zone.

Glowka, D.A.

1991-01-01

103

Distinct quaternary structures of the AAA+ Lon protease control substrate degradation  

E-print Network

Lon is an ATPase associated with cellular activities (AAA+) protease that controls cell division in response to stress and also degrades misfolded and damaged proteins. Subunits of Lon are known to assemble into ring-shaped ...

Vieux (Kloss), Ellen

104

Survey of degradation modes of candidate materials for high-level radioactive-waste disposal containers  

SciTech Connect

This volume surveys the effects of welding on the degradation modes of three austenitic alloys: Types 304L and 316L stainless steels and Alloy 825. These materials are candidates for the fabrication of containers for the long-term storage of high-level nuclear waste. The metallurgical characteristics of fusion welds are reviewed here and related to potential degradation modes of the containers. Three specific areas are discussed in depth: (1) decreased resistance to corrosion in the forms of preferential corrosion, sensitization, and susceptibility to stress corrosion cracking, (2) hot cracking in the heat-affected zone and the weld zone, and (3) formation of intermetallic phases. The austenitic alloys are ranked as follows in terms of overall weldability: Alloy 825 (best) > Type 316L stainless steel > Type 304L stainless steel (worst). 108 refs., 31 figs., 7 tabs.

Strum, M.J.; Weiss, H.; Farmer, J.C. (Lawrence Livermore National Lab., CA (USA)); Bullen, D.B. (Science and Engineering Associates, Inc., Pleasanton, CA (USA))

1988-06-01

105

Stability of CIGS Solar Cells and Component Materials Evaluated by a Step-Stress Accelerated Degradation Test Method: Preprint  

SciTech Connect

A step-stress accelerated degradation testing (SSADT) method was employed for the first time to evaluate the stability of CuInGaSe2 (CIGS) solar cells and device component materials in four Al-framed test structures encapsulated with an edge sealant and three kinds of backsheet or moisture barrier film for moisture ingress control. The SSADT exposure used a 15oC and then a 15% relative humidity (RH) increment step, beginning from 40oC/40%RH (T/RH = 40/40) to 85oC/70%RH (85/70) as of the moment. The voluminous data acquired and processed as of total DH = 3956 h with 85/70 = 704 h produced the following results. The best CIGS solar cells in sample Set-1 with a moisture-permeable TPT backsheet showed essentially identical I-V degradation trend regardless of the Al-doped ZnO (AZO) layer thickness ranging from standard 0.12 ?m to 0.50 ?m on the cells. No clear 'stepwise' feature in the I-V parameter degradation curves corresponding to the SSADT T/RH/time profile was observed. Irregularity in I-V performance degradation pattern was observed with some cells showing early degradation at low T/RH < 55/55 and some showing large Voc, FF, and efficiency degradation due to increased series Rs (ohm-cm2) at T/RH ? 70/70. Results of (electrochemical) impedance spectroscopy (ECIS) analysis indicate degradation of the CIGS solar cells corresponded to increased series resistance Rs (ohm) and degraded parallel (minority carrier diffusion/recombination) resistance Rp, capacitance C, overall time constant Rp*C, and 'capacitor quality' factor (CPE-P), which were related to the cells? p-n junction properties. Heating at 85/70 appeared to benefit the CIGS solar cells as indicated by the largely recovered CPE-P factor. Device component materials, Mo on soda lime glass (Mo/SLG), bilayer ZnO (BZO), AlNi grid contact, and CdS/CIGS/Mo/SLG in test structures with TPT showed notable to significant degradation at T/RH ? 70/70. At T/RH = 85/70, substantial blistering of BZO layers on CIGS cell pieces was observed that was not seen on BZO/glass, and a CdS/CIGS sample displayed a small darkening and then flaking feature. Additionally, standard AlNi grid contact was less stable than thin Ni grid contact at T/RH ? 70/70. The edge sealant and moisture-blocking films were effective to block moisture ingress, as evidenced by the good stability of most CIGS solar cells and device components at T/RH = 85/70 for 704 h, and by preservation of the initial blue color on the RH indicator strips. The SSADT experiment is ongoing to be completed at T/RH = 85/85.

Pern, F. J.; Noufi, R.

2012-10-01

106

Occurrence, degradation, and effect of polymer-based materials in the environment.  

PubMed

There is now a plethora of polymer-based materials (PBMs) on the market, because of the increasing demand for cheaper consumable goods, and light-weight industrial materials. Each PBM constitutes a mixture of their representative polymer/sand their various chemical additives. The major polymer types are polyethylene, polypropylene,and polyvinyl chloride, with natural rubber and biodegradable polymers becoming increasingly more important. The most important additives are those that are biologically active, because to be effective such chemicals often have properties that make them resistant to photo-degradation and biodegradation. During their lifecycle,PBMs can be released into the environment form a variety of sources. The principal introduction routes being general littering, dumping of unwanted waste materials,migration from landfills and emission during refuse collection. Once in the environment,PBMs are primarily broken down by photo-degradation processes, but due to the complex chemical makeup of PBMs, receiving environments are potentially exposed to a mixture of macro-, meso-, and micro-size polymer fragments, leached additives, and subsequent degradation products. In environments where sunlight is absent (i.e., soils and the deep sea) degradation for most PBMs is minimal .The majority of literature to date that has addressed the environmental contamination or disposition of PBMs has focused on the marine environment. This is because the oceans are identified as the major sink for macro PBMs, where they are known to present a hazard to wildlife via entanglement and ingestion. The published literature has established the occurrence of microplastics in marine environment and beach sediments, but is inadequate as regards contamination of soils and freshwater sediments. The uptake of microplastics for a limited range of aquatic organisms has also been established, but there is a lack of information regarding soil organisms, and the long-term effects of microplastic uptake are also less well understood.There is currently a need to establish appropriate degradation test strategies consistent with realistic environmental conditions, because the complexity of environmental systems is lost when only one process (e.g., hydrolysis) is assessed in isolation. Enhanced methodologies are also needed to evaluate the impact of PBMs to soil and freshwater environments. PMID:24158578

Lambert, Scott; Sinclair, Chris; Boxall, Alistair

2014-01-01

107

High intensity 5 eV O-atom exposure facility for material degradation studies  

NASA Technical Reports Server (NTRS)

An atomic oxygen exposure facility was developed for studies of material degradation. The goal of these studies is to provide design criteria and information for the manufacture of long life (20 to 30 years) construction materials for use in low Earth orbit. The studies that are being undertaken will provide: (1) absolute reaction cross sections for the engineering design problems, (2) formulations of reaction mechanisms for use in the selection of suitable existing materials and the design of new more resistant ones, and (3) the calibration of flight hardware (mass spectrometers, etc.) in order to directly relate experiments performed in low Earth orbit to ground based investigations. The facility consists of a CW laser sustained discharge source of O-atoms, an atomic beam formation and diagnostics system, a spinning rotor viscometer, and provision for using the system for calibration of actual flight instruments.

Cross, J. B.; Spangler, L. H.; Hoffbauer, M. A.; Archuleta, F. A.; Leger, Lubert; Visentine, James; Hunton, Don E.; Cross, J. B.

1986-01-01

108

Degradation of 1-hydroxy-2,4-dinitrobenzene from aqueous solutions by electrochemical oxidation: role of anodic material.  

PubMed

Electrochemical oxidation (ECOx) of 1-hydroxy-2,4-dinitrobenzene (or 2,4-dinitrophenol: 2,4-DNP) in aqueous solutions by electrolysis under galvanostatic control was studied at Pb/PbO2, Ti/SnO2, Ti/IrxRuySnO2 and Si/BDD anodes as a function of current density applied. Oxidative degradation of 2,4-DNP has clearly shown that electrode material and the current density applied were important parameters to optimize the oxidation process. It was observed that 2,4-DNP was oxidized at few substrates to CO2 with different results, obtaining good removal efficiencies at Pb/PbO2, Ti/SnO2 and Si/BDD anodes. Trends in degradation way depend on the production of hydroxyl radicals (OH) on these anodic materials, as confirmed in this study. Furthermore, HPLC results suggested that two kinds of intermediates were generated, polyhydroxylated intermediates and carboxylic acids. The formation of these polyhydroxylated intermediates seems to be associated with the denitration step and substitution by OH radicals on aromatic rings, this being the first proposed step in the reaction mechanism. These compounds were successively oxidized, followed by the opening of aromatic rings and the formation of a series of carboxylic acids which were at the end oxidized into CO2 and H2O. On the basis of these information, a reaction scheme was proposed for each type of anode used for 2,4-D oxidation. PMID:24462986

Quiroz, Marco A; Sánchez-Salas, José L; Reyna, Silvia; Bandala, Erick R; Peralta-Hernández, Juan M; Martínez-Huitle, Carlos A

2014-03-15

109

Ecological and biogeochemical aspects of microbial degradation of phenolic materials in the California coastal marine environment  

SciTech Connect

Phenolic materials are found in numerous environments, particularly in coastal environments due to anthropogenic pollution, in situ production by marine organisms, and from riverine humic materials flowing into estuaries. They are used as model compounds for the study of microbially mediated organic carbon dynamics in coastal systems. To determine the rates and utilization dynamics of phenolic materials by coastal marine bacteria, a sequential approach was used in which marine bacteria were first assayed to determine their ability to utilize phenolics, various sites in the California coastal zone were analyzed qualitatively and quantitatively for phenolic materials, a method was developed to determine microbial utilization rates of phenolic materials and finally, utilization rates of p-cresol were determined at ambient concentrations. Phenol, cresol isomers (o-, m-, and p-), catechols, and methoxyphenols were the predominant phenolic materials identified. Concentrations ranged from about 2.5 to 370 ng[center dot]1[sup [minus]1]. Biodegradation rates of p-cresol were measured in five coastal areas. Rates of microbial utilization were high, up to 35.5 ng[center dot]1[sup [minus]1][center dot]hr[sup [minus]1] in San Francisco Bay. Turnover times were calculated using the measured ambient concentration of p-cresol and ranged from 1.72 hours (San Francisco Bay) to 37 hours (at Spanish Landing in San Diego Bay). Utilization kinetics indicated microbial degradation of more complex, humic type material containing phenolic moieties. It is concluded biodegradation of phenolic compounds plays a major role in the biogeochemistry of organic materials in coastal marine environments. Rates for the breakdown of the phenolic component of humic materials in estuarine environments indicate that microbially mediated turnover times are considerably faster than for other means suggested, such as photodegradation or sedimentation.

Boyd, T.J.

1993-01-01

110

Thermal/chemical degradation of ceramic candle filter materials. Final report, September 1988--October 1994  

SciTech Connect

High-temperature ceramic candle filters are being developed for use in advanced power generation systems such as the Integrated Gasification Combined Cycle (IGCC), Pressurized Fluidized-Bed Combustor (PFBC), and Direct Coal-Fired Turbine (DCFT). The direct firing of coal produces particulate matter which must be removed to meet both environmental and process limitations. The ceramic candles increase the efficiency of the advanced power generation systems and protect downstream equipment from erosion and impingement of particulate matter in the hot exhaust gases. Ceramic candle filters are rigid, closed-ended (capped on one side) porous cylinders which generally have a flange on the open-ended side. The flange at the open end allows the candle to be suspended by a tubesheet in the filter vessel. Candle filters have shown promise, but have also encountered durability problems during use in hostile, high-temperature environments. Limitations in the candle lifetime lower the economic advantages of using candle filters for this application. Candles typically fail by cracking at the flange or in the body of the candle. The objective of this project was to test and analyze ceramic candle filter materials and to evaluate the degradation mechanisms. The tests were conducted such that the effects of each degradation mechanism could be examined. Separately. The overall objective of the project was to: (a) develop a better understanding of the thermal and chemical degradation mechanisms of ceramic candle filter materials in advanced coal utilization projects, (b) develop test procedures, and (c) recommend changes to increase filter lifetime. 15 refs., 67 figs., 17 tabs.

NONE

1995-01-01

111

NON-THERMAL PLASMA TECHNOLOGY FOR DEGRADATION OF ORGANIC COMPOUNDS IN WASTEWATER CONTROL: A CRITICAL REVIEW  

Microsoft Academic Search

Non-thermal plasma is an emerging technique in environmental pollution control technology, produced by the high-voltage discharge processes and therefore a large amount of high energy electrons and active species are generated. The degradation of difficult-degraded organic pollutions will be greatly enhanced by the active species generated from non-thermal plasma process. However, research on non-thermal plasma technology on organic wastewater cleaning

Hsu-Hui Cheng; Shiao-Shing Chen; Yu-Chi Wu; Din-Lit Ho

112

Experimental simulation of materials degradation of plasma-facing components using lasers  

NASA Astrophysics Data System (ADS)

The damage and erosion of plasma-facing components (PFCs) due to extremely high heat loads and particle bombardment is a key issue for the nuclear fusion community. Currently high current ion and electron beams are used in laboratories for simulating the behaviour of PFC materials under ITER-like conditions. Our results indicate that high-power nanosecond lasers can be used for laboratory simulation of high heat flux PFC material degradation. We exposed tungsten (W) surfaces with repetitive laser pulses from a nanosecond laser with a power density ˜ a few GW cm-2. Emission spectroscopic analysis showed that plasma features at early times followed by intense particle emission at later times. Analysis of laser-exposed W surface demonstrated cracks and grain structures. Our results indicate that the typical particle emission features from laser-irradiated tungsten are consistent with high-power particle beam simulation results.

Farid, N.; Harilal, S. S.; El-Atwani, O.; Ding, H.; Hassanein, A.

2014-01-01

113

Cometabolic degradation of trichloroethene by Rhodococcus sp. strain L4 immobilized on plant materials rich in essential oils.  

PubMed

The cometabolic degradation of trichloroethene (TCE) by Rhodococcus sp. L4 was limited by the loss of enzyme activity during TCE transformation. This problem was overcome by repeated addition of inducing substrates, such as cumene, limonene, or cumin aldehyde, to the cells. Alternatively, Rhodococcus sp. L4 was immobilized on plant materials which contain those inducers in their essential oils. Cumin seeds were the most suitable immobilizing material, and the immobilized cells tolerated up to 68 muM TCE and degraded TCE continuously. The activity of immobilized cells, which had been inactivated partially during TCE degradation, could be reactivated by incubation in mineral salts medium without TCE. These findings demonstrate that immobilization of Rhodococcus sp. L4 on plant materials rich in essential oils is a promising method for efficient cometabolic degradation of TCE. PMID:20472723

Suttinun, Oramas; Müller, Rudolf; Luepromchai, Ekawan

2010-07-01

114

Factors Controlling Elevated Temperature Strength Degradation of Silicon Carbide Composites  

NASA Technical Reports Server (NTRS)

For 5 years, the cooperative agreement NCC3-763 has focused on the development and understanding of Sic-based composites. Most of the work was performed in the area of SiC fiber-reinforced composites for UEET and NGLT and in collaboration with Goodrich Corporation under a partially reimbursable Space Act Agreement. A smaller amount of work was performed on C fiber-reinforced SiC matrix composites for NGLT. Major accomplishments during this agreement included: Improvements to the interphase used in melt-infiltrated (MI) SiC/SiC composites which increases the life under stressed-oxidation at intermediate temperatures referred to as "outside-debonding". This concept is currently in the patent process and received a Space Act Award. Mechanistic-based models of intermediate temperature degradation for MI SiC/SiC Quantification and relatively robust relationships for matrix crack evolution under stress in SiC/SiC composites which serve as the basis for stress-strain and elevated temperature life models The furthering of acoustic emission as a useful tool in composite damage evolution and the extension of the technique to other composite systems Development of hybrid C-SiC fiber-reinforced SiC matrix composites Numerous presentations at conferences, industry partners, and government centers and publications in recognized proceedings and journals. Other recognition of the author's accomplishments by NASA with a TGIR award (2004), NASA's Medal for Public Service (2004), and The American Ceramic Society s Richard M. Fulrath Award (2005). The following will briefly describe the work of the past five years in the three areas of interest: SiC/SiC composite development, mechanistic understanding and modeling of SiC/SiC composites, and environmental durability of C/SiC composites. More detail can be found in the publications cited at the end of this report.

2005-01-01

115

Bio-inspired Supramolecular Assemblies and Porous Materials for the Degradation of Organophosphate Nerve Agents  

NASA Astrophysics Data System (ADS)

This thesis reports the synthesis of bio-inspired supramolecular assemblies and porous materials that are catalytically active in the degradation of organophosphate nerve agents. The first catalysts described are a series of cofacial metalloporphyrin dimers modeled after the active site of phosphotriesterase that were modularly prepared from a single porphyrin building block and shown to catalyze the methanolysis of p-nitrophenyl diphenyl phosphate (PNPDPP), a simulant for nerve agents. Notably, tuning the active sites inside the cavities of these dimers, from ZnII metal centers to Al-OMe moieties, affords an enhanced nucleophilic environment where a high concentration of methoxy ligands becomes available for reaction with encapsulated phosphate triesters. Up to a 1300-fold rate acceleration over the uncatalyzed reaction can be achieved via a combination of cavity-localized Lewis-acid activation and methoxide-induced methanolysis. Based on the design principles learned from the aforementioned solution-phase Al(porphyrin) dimers, a heterogeneous porous organic polymer (POP) catalyst was synthesized by incorporating an Al(porphyrin) functionalized with a large axial ligand into a POP using a cobalt-catalyzed acetylene trimerization strategy. Removal of the axial ligand afforded a microporous material that is capable of encapsulating and solvolytically degrading PNPDPP. Supercritical CO 2 processing of the Al(porphyrin)-based POP dramatically increased the pore size and volume, allowing for significantly higher catalytic activities. The syntheses of porphyrin-based POPs with tunable pore diameters and volumes have also been attempted. SnIV(porphyrins) functionalized with bulky trans-diaxial ligands can be incorporated into POPs. Post-synthesis removal of the ligands reveal POPs with a tunable range of micro- and mesopores as well as tunable pore volumes. Expanding upon the idea that active sites that can both bind substrates and deliver nucleophiles should be active catalysts for the degradation of organophosphates, metal catecholate POPs were also explored. Metallation of catechol POPs with La(acac)3 affords a catalytically active microporous network for the solvolytic and hydrolytic degradation of the toxic organophosphate compound methyl paraoxon. As the Lewis-acidic LaIII metal ion can bind up to 9 substrates, its incorporation into a catechol-decorated POP affords a microporous environment capable of pre-concentrating methyl paraoxon in the presence of a large number of hydroxylated nucleophiles for enhanced catalysis.

Totten, Ryan K.

116

Control of protein function through regulated protein degradation: biotechnological and biomedical applications.  

PubMed

Targeted protein degradation is crucial for the correct function and maintenance of a cell. In bacteria, this process is largely performed by a handful of ATP-dependent machines, which generally consist of two components - an unfoldase and a peptidase. In some cases, however, substrate recognition by the protease may be regulated by specialized delivery factors (known as adaptor proteins). Our detailed understanding of how these machines are regulated to prevent uncontrolled degradation within a cell has permitted the identification of novel antimicrobials that dysregulate these machines, as well as the development of tunable degradation systems that have applications in biotechnology. Here, we focus on the physiological role of the ClpP peptidase in bacteria, its role as a novel antibiotic target and the use of protein degradation as a biotechnological approach to artificially control the expression levels of a protein of interest. PMID:23920496

Nagpal, Jyotsna; Tan, Ju Lin; Truscott, Kaye N; Heras, Begoña; Dougan, David A

2013-01-01

117

Distinct quaternary structures of the AAA+ Lon protease control substrate degradation  

PubMed Central

Lon is an ATPase associated with cellular activities (AAA+) protease that controls cell division in response to stress and also degrades misfolded and damaged proteins. Subunits of Lon are known to assemble into ring-shaped homohexamers that enclose an internal degradation chamber. Here, we demonstrate that hexamers of Escherichia coli Lon also interact to form a dodecamer at physiological protein concentrations. Electron microscopy of this dodecamer reveals a prolate structure with the protease chambers at the distal ends and a matrix of N domains forming an equatorial hexamer–hexamer interface, with portals of ?45 Å providing access to the enzyme lumen. Compared with hexamers, Lon dodecamers are much less active in degrading large substrates but equally active in degrading small substrates. Our results support a unique gating mechanism that allows the repertoire of Lon substrates to be tuned by its assembly state. PMID:23674680

Vieux, Ellen F.; Wohlever, Matthew L.; Chen, James Z.; Sauer, Robert T.; Baker, Tania A.

2013-01-01

118

Fuzzy controllers in nuclear material accounting  

SciTech Connect

Fuzzy controllers are applied to predicting and modeling a time series, with particular emphasis on anomaly detection in nuclear material inventory differences. As compared to neural networks, the fuzzy controllers can operate in real time; their learning process does not require many iterations to converge. For this reason fuzzy controllers are potentially useful in time series forecasting, where the authors want to detect and identify trends in real time. They describe an object-oriented implementation of the algorithm advanced by Wang and Mendel. Numerical results are presented both for inventory data and time series corresponding to chaotic situations, such as encountered in the context of strange attractors. In the latter case, the effects of noise on the predictive power of the fuzzy controller are explored.

Zardecki, A.

1994-10-01

119

Insider Threat - Material Control and Accountability Mitigation  

SciTech Connect

The technical objectives of nuclear safeguards are (1) the timely detection of diversion of significant quantities of nuclear material from peaceful uses to the manufacture of nuclear weapons or other nuclear explosive devices or for purposes unknown and (2) the deterrence of such diversion by the risk of early detection. The safeguards and security program must address both outsider threats and insider threats. Outsider threats are primarily addressed by the physical protection system. Insider threats can be any level of personnel at the site including passive or active insiders that could attempt protracted or abrupt diversion. This could occur by an individual acting alone or by collusion between an individual with material control and accountability (MC&A) responsibilities and another individual who has responsibility or control within both the physical protection and the MC&A systems. The insider threat is one that must be understood and incorporated into the safeguards posture. There have been more than 18 documented cases of theft or loss of plutonium or highly enriched uranium. The insider has access, authority, and knowledge, as well as a set of attributes, that make him/her difficult to detect. An integrated safeguards program is designed as a defense-in-depth system that seeks to prevent the unauthorized removal of nuclear material, to provide early detection of any unauthorized attempt to remove nuclear material, and to rapidly respond to any attempted removal of nuclear material. The program is also designed to support protection against sabotage, espionage, unauthorized access, compromise, and other hostile acts that may cause unacceptable adverse impacts on national security, program continuity, the health and safety of employees, the public, or the environment. Nuclear MC&A play an essential role in the capabilities of an integrated safeguards system to deter and detect theft or diversion of nuclear material. An integrated safeguards system with compensating mitigation can decrease the risk of an insider performing a malicious act without detection.

Powell, Danny H [ORNL] [ORNL; Elwood Jr, Robert H [ORNL] [ORNL; Roche, Charles T [ORNL] [ORNL

2011-01-01

120

Degradation of recycled PET fibers in Portland cement-based materials  

SciTech Connect

In order to investigate the durability of recycled PET fibers embedded in cement-based materials, fiber-reinforced mortar specimens were tested until 164 days after mixing. Compressive, tensile, and flexural strengths, elasticity modulus, and toughness of the specimens were determined. The mortars were also analyzed by SEM. The results have shown that PET fibers have no significant influence on mortars strengths and elasticity modulus. However, the toughness indexes I {sub 5}, I {sub 10}, and I {sub 20} decreased with time due to the degradation of PET fibers by alkaline hydrolysis when embedded in the cement matrix. Fourier transform infrared spectroscopy (FT-IR) and SEM analysis of PET fibers immersed and kept for 150 days in alkaline solutions supported the conclusions.

Silva, D.A. [Universidade Federal de Santa Catarina, Department of Civil Engineering, C.P. 476, CEP 88040-900, Florianopolis, SC (Brazil)]. E-mail: denise@ecv.ufsc.br; Betioli, A.M. [Universidade Federal de Santa Catarina, Department of Civil Engineering, C.P. 476, CEP 88040-900, Florianopolis, SC (Brazil); Gleize, P.J.P. [Universidade Federal de Santa Catarina, Department of Civil Engineering, C.P. 476, CEP 88040-900, Florianopolis, SC (Brazil); Roman, H.R. [Universidade Federal de Santa Catarina, Department of Civil Engineering, C.P. 476, CEP 88040-900, Florianopolis, SC (Brazil); Gomez, L.A. [Universidade Federal de Santa Catarina, Department of Civil Engineering, C.P. 476, CEP 88040-900, Florianopolis, SC (Brazil); Ribeiro, J.L.D. [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil)

2005-09-01

121

Radiation Induced Degradation of White Thermal Control Paint  

NASA Technical Reports Server (NTRS)

This paper details a comparison analysis of the zinc-oxide pigmented white thermal control paints Z-93 and Z-93P. Both paints were simultaneously exposed to combined space environmental effects and analyzed using an in-vacuo reflectance technique. The dose applied to the paints was approximately equivalent to 5 yr in a geosynchronous orbit. This comparison analysis showed that Z-93P is an acceptable substitute for Z-93. Irradiated samples of Z-93 and Z-93P were subjected to additional exposures of ultraviolet (UV) radiation and analyzed using the in-vacuo reflectance technique to investigate UV activated reflectance recovery. Both samples showed minimal UV activated reflectance recovery after an additional 190 equivalent Sun hour (ESH) exposure. Reflectance response utilizing nitrogen as a repressurizing gas instead of air was also investigated. This investigation found the rates of reflectance recovery when repressurized with nitrogen are slower than when repressurized with air.

Edwards, D. L.; Zwiener, J. M.; Wertz, G. E.; Vaughn, Jason A.; Kamenetzky, Rachel R.; Finckenor, M. M.; Meshishnek, M. J.

1998-01-01

122

Radiation Induced Degradation of White Thermal Control Paint  

NASA Technical Reports Server (NTRS)

This paper details a comparison analysis of the zinc-oxide pigmented white thermal control paints Z-93 and Z-93P. Both paints were simultaneously exposed to combined space environmental effects and analyzed using an in-vacuo reflectance technique. The dose applied to the paints was approximately equivalent to 5 yr in a geosynchronous orbit. This comparison analysis showed that Z-93P is an acceptable substitute for Z-93. Irradiated samples of Z-93 and Z-93P were subjected to additional exposures of ultraviolet (UV) radiation and analyzed using the in-vacuo reflectance technique to investigate UV activated reflectance recovery. Both samples showed minimal UV activated reflectance recovery after an additional 190 equivalent Sun hour (ESH) exposure. Reflectance response utilizing nitrogen as a repressurizing gas instead of air was also investigated. This investigation found the rates of reflectance recovery when repressurized with nitrogen are slower than when repressurized with air.

Edwards, D. L.; Zwiener, J. M.; Wertz, G. E.; Vaughn, Jason A.; Kamenetzky, Rachel R.; Finckenor, M. M.; Meshishnek, M. J.

1999-01-01

123

Survey of degradation modes of candidate materials for high-level radioactive-waste disposal containers  

SciTech Connect

Three copper-based alloys, CDA 102 (oxygen-free, high-purity copper), CDA 613 (aluminum bronze), and CDA 715 (Cu-30Ni), are candidates for the fabrication of high-level radioactive-waste disposal containers. Waste will include spent fuel assemblies from reactors as well as borosilicate glass, and will be sent to the prospective repository site at Yucca Mountain in Nye County, Nevada. The decay of radionuclides will result in the generation of substantial heat and in fluxes of gamma radiation outside the containers. In this environment, container materials might degrade by atmospheric oxidation, general aqueous phase corrosion, localized corrosion (LC), and stress corrosion cracking (SCC). This volume is a critical survey of available data on pitting and crevice corrosion of the copper-based candidates. Pitting and crevice corrosion are two of the most common forms of LC of these materials. Data on the SCC of these alloys is surveyed in Volume 4. Pitting usually occurs in water that contains low concentrations of bicarbonate and chloride anions, such as water from Well J-13 at the Nevada Test Site. Consequently, this mode of degradation might occur in the repository environment. Though few quantitative data on LC were found, a tentative ranking based on pitting corrosion, local dealloying, crevice corrosion, and biofouling is presented. CDA 102 performs well in the categories of pitting corrosion, local dealloying, and biofouling, but susceptibility to crevice corrosion diminishes its attractiveness as a candidate. The cupronickel alloy, CDA 715, probably has the best overall resistance to such localized forms of attack. 123 refs., 11 figs., 3 tabs.

Farmer, J.C.; Van Konynenburg, R.A.; McCright, R.D. (Lawrence Livermore National Lab., CA (USA)); Gdowski, G.E. (Science and Engineering Associates, Inc., Pleasanton, CA (USA))

1988-06-01

124

Integrated design of structures, controls, and materials  

NASA Technical Reports Server (NTRS)

In this talk we shall discuss algorithms and CAD tools for the design and analysis of structures for high performance applications using advanced composite materials. An extensive mathematical theory for optimal structural (e.g., shape) design was developed over the past thirty years. Aspects of this theory have been used in the design of components for hypersonic vehicles and thermal diffusion systems based on homogeneous materials. Enhancement of the design methods to include optimization of the microstructure of the component is a significant innovation which can lead to major enhancements in component performance. Our work is focused on the adaptation of existing theories of optimal structural design (e.g., optimal shape design) to treat the design of structures using advanced composite materials (e.g., fiber reinforced, resin matrix materials). In this talk we shall discuss models and algorithms for the design of simple structures from composite materials, focussing on a problem in thermal management. We shall also discuss methods for the integration of active structural controls into the design process.

Blankenship, G. L.

1994-01-01

125

Peptide assembly for nanoscale control of materials  

NASA Astrophysics Data System (ADS)

Self-assembly of molecules is an attractive materials construction strategy due to its simplicity in application. By considering peptidic, charged synthetic molecules in the bottom-up materials self-assembly design process, one can take advantage of inherently biomolecular attributes; intramolecular folding events, secondary structure, and electrostatic interactions; in addition to more traditional self-assembling molecular attributes such as amphiphilicty, to define hierarchical material structure and consequent properties. Design strategies for materials self-assembly based on small (less than 24 amino acids) beta-hairpin peptides will be discussed. Self-assembly of the peptides is predicated on an intramolecular folding event caused by desired solution properties. Importantly, kinetics of self-assembly can be tuned in order to control gelation time. The final gel behaves as a shear thinning, but immediately rehealing, solid that is potentially useful for cell injection therapies. The morphological, and viscoelastic properties of these peptide hydrogels will be discussed. In addition, slight changes in peptide primary sequence can have drastic effects on the self-assembled morphology. Additional sequences will be discussed that do not form hydrogels but rather form nanoscale templates for inorganic material assembly.

Pochan, Darrin

2011-03-01

126

D d ti f M h i lDegradation of Mechanical Properties in Composite Materials  

E-print Network

in selected cases to establish coating cracking strains. · Task 2: Testing for environmental effects water; control specimens to be tested in heated or cooled laboratory air. The effects of coatings. Characterize these materials for strength and fatigue resistance under ambient laboratory conditions if data

127

In and Out of the ER: Protein Folding, Quality Control, Degradation, and Related Human Diseases  

E-print Network

1394 A. Human diseases caused by defective protein folding or trafficking: selected examples 1394 BIn and Out of the ER: Protein Folding, Quality Control, Degradation, and Related Human Diseases, and Related Human Diseases. Physiol Rev 87: 1377­1408, 2007; doi:10.1152/physrev.00050.2006.--A substantial

Hebert, Daniel N.

128

Controls on methane released through ebullition in peatlands affected by permafrost degradation  

E-print Network

Controls on methane released through ebullition in peatlands affected by permafrost degradation, Hamilton, Ontario, Canada Abstract Permafrost thaw in peat plateaus leads to the flooding of surface soils peat as well as deeper, previously frozen, permafrost carbon (C). We used a network of bubble traps

Ickert-Bond, Steffi

129

Control of hot carrier degradation in LDMOS devices by a dummy gate field plate: experimental demonstration  

Microsoft Academic Search

It is experimentally demonstrated that hot carrier degradation in high voltage LDMOS devices can be minimized by adding a dummy gate field plate, DGFP, over the drain drift region close to the gate. The level of on resistance increase due to hot carrier stress can be controlled by design with the amount of the DGFP overlap of the drift region.

Ayman Shibib; Shuming Xu; Zhijian Xie; Peter Gammel; Marco Mastrapasqua; Isik Kizilyalli

2004-01-01

130

Ethylene receptor degradation controls the timing of ripening in tomato fruit  

E-print Network

Ethylene receptor degradation controls the timing of ripening in tomato fruit Brian M. Kevany-mail hjklee@ifas.ufl.edu). Summary Fruit ripening in tomato requires the coordination of both developmental modification. Climacteric fruits such as tomato are characterized by an increase in respiration

Klee, Harry J.

131

Thermal control materials on EOIM-3  

NASA Technical Reports Server (NTRS)

Thermal control paints, anodized aluminum, and beta cloth samples were flown on STS-46 as part of the Evaluation of Oxygen Interaction with Materials Experiment (EOIM-3). The thermal control paints flown on EOIM-3 include ceramic and polyurethane-based paints. Passively exposed samples are compared to actively heated samples and controlled exposure samples. Optical property measurements of absorptivity, emissivity, and spectrofluorescence are presented for each paint. Several variations of anodized aluminum, including chromic acid anodize, sulfuric acid anodize, and boric/sulfuric acid anodize were flown on the actively heated trays and the passive exposure trays. The post-flight optical properties are within tolerances for these materials. Also flown were two samples of yellow anodized aluminum. The yellow anodized aluminum samples darkened noticeably. Samples of aluminized and unaluminized beta cloth, a fiberglass woven mat impregnated with TFE Teflon, were flown with passive exposure to the space environment. Data from this part of the experiment is correlated to observations from LDEF and erosion of the Teflon thin film samples also flown on EOIM-3 and LDEF.

Finckenor, Miria M.; Linton, Roger C.; Kamenetzky, Rachel R.; Vaughn, Jason A.

1995-01-01

132

Survey of degradation modes of candidate materials for high-level radioactive-waste disposal containers  

SciTech Connect

Six alloys are being considered as possible materials for the fabrication of containers for the disposal of high-level radioactive waste. Three of these candidate materials are copper-based alloys: CDA 102 (oxygen-free copper), CDA 613 (Cu-7Al), and CDA 715 (Cu-30Ni). The other three are iron- to nickel-based austenitic materials: Types 304L and 316L stainless steels and Alloy 825. Radioactive waste will include spent-fuel assemblies from reactors as well as waste in borosilicate glass and will be sent to the prospective site at Yucca Mountain, Nevada, for disposal. The waste-package containers must maintain substantially complete containment for at least 300 yr and perhaps as long as 1000 yr. During the first 50 yr after emplacement, the containers must be retrievable from the disposal site. Shortly after emplacement of the containers in the repository, they will be exposed to high temperatures and high gamma radiation fields from the decay of high-level waste. This radiation will promote the radiolytic decomposition of moist air to hydrogen. This volume surveys the available data on the effects of hydrogen on the six candidate alloys for fabrication of the containers. For copper, the mechanism of hydrogen embrittlement is discussed, and the effects of hydrogen on the mechanical properties of the copper-based alloys are reviewed. The solubilities and diffusivities of hydrogen are documented for these alloys. For the austenitic materials, the degradation of mechanical properties by hydrogen is documented. The diffusivity and solubility of hydrogen in these alloys are also presented. For the copper-based alloys, the ranking according to resistance to detrimental effects of hydrogen is: CDA 715 (best) > CDA 613 > CDA 102 (worst). For the austenitic alloys, the ranking is: Type 316L stainless steel {approx} Alloy 825 > Type 304L stainless steel (worst). 87 refs., 19 figs., 8 tabs.

Gdowski, G.E.; Bullen, D.B. (Science and Engineering Associates, Inc., Pleasanton, CA (USA))

1988-08-01

133

Thermal and chemical degradation of inorganic membrane materials. Final report, August 1992--May 1995  

SciTech Connect

SRI International conducted a theoretical and experimental program to evaluate the long-term thermal and chemical degradation of inorganic membranes that are being developed to separate the gaseous products of coal gasification. A variety of developmental efforts are underway, including a number of projects sponsored by the US Department of Energy (DOE), to improve the selectivity and permeability of porous inorganic membranes. DOE is also sponsoring efforts to extend the use of metallic membranes to new applications. Most developmental efforts have focused on hydrogen separation by inorganic membranes, which may be used to maximize hydrogen production from coal gas or to remove H{sub 2}S and NH{sub 3} contaminants via thermal or catalytic decomposition in integrated-gasification combined-cycle (IGCC) systems. Inorganic membranes that have a high separation efficiency and exhibit both thermal and chemical stability would improve the economics of power generation from coal. Membrane materials that have been investigated include glass (silica), alumina, carbon, and metals (Pd and Pt). This report describes inorganic membrane materials, long term membrane exposure tests, membrane permeation tests, coal gasifier exposure tests, conclusions, and recommendations.

Damle, A.S.; Krishnan, G.N.; Sanjurjo, A.; Wood, B.J.; Lau, K.H.

1995-05-01

134

Analysis of degradation phenomena in ancient, traditional and improved building materials of historical monuments  

NASA Astrophysics Data System (ADS)

A review is presented on constructive techniques plus materials and the processes involved in degradation phenomena observed in two historical monuments: the Zambujeiro dolmen (Portugal) and the Roman Aqueduct of Carthage (Tunisia). Dolmens are particularly impressive megalithic constructions for the dimensions of granite blocks. At Zambujeiro, the upright stones have undergone a catastrophic evolution after the archaeological exploitation due to accelerated weathering through a process apparently distinct from natural granite decay in nearby outcrops. The biological attack of granite minerals by lichen exudates has emphasized the hazardous character of bromine and more has been learnt about construction techniques, namely, the insertion in the mound of an impermeable clay stratum that hinders water penetration into the dolmen chamber. The characterization of original Roman ashlar blocks, including masonry and the diagnosis of Byzantine and medieval reconstruction testimonies in the Aqueduct of Carthage were the object of a detailed study by X-ray diffraction and synchrotron radiation X-ray fluorescence. Traditional constructive techniques and local construction materials were studied and successive historical, modern and recent rehabilitations were reappraised.

Figueiredo, M. O.; Silva, T. P.; Veiga, J. P.

2008-07-01

135

Adaptive binary material classification of an unknown object using polarimetric images degraded by atmospheric turbulence  

NASA Astrophysics Data System (ADS)

An improved binary material-classification algorithm using passive polarimetric imagery degraded by atmospheric turbulence is presented. The technique implements a modified version of an existing polarimetric blind-deconvolution algorithm in order to remove atmospheric distortion and correctly classify the unknown object. The classification decision, dielectric or metal in this case, is based on degree of linear polarization (DoLP) estimates provided by the blind-deconvolution algorithm augmented by two DoLP priors - one statistically modeling the polarization behavior of metals and the other statistically modeling the polarization behavior of dielectrics. The DoLP estimate which maximizes the log-likelihood function determines the image pixel's classification. The method presented here significantly improves upon a similar published polarimetric classification method by adaptively updating the DoLP priors as more information becomes available about the scene. This new adaptive method significantly extends the range of validity of the existing polarimetric classification technique to near-normal collection geometries where most polarimetric material classifiers perform poorly. In this paper, brief reviews of the polarimetric blind-deconvolution algorithm and the functional forms of the DoLP priors are provided. Also provided is the methodology for making the algorithm adaptive including three techniques for updating the DoLP priors using in-progress DoLP estimates. Lastly, the proposed technique is experimentally validated by comparing classification results of two dielectric and metallic samples obtained using the new method to those obtained using the existing technique.

Kim, Mu J.; Hyde, Milo W.

2012-10-01

136

Bacteria Holding Time and DegradationBacteria Holding Time and Degradation Presented to CA State Water Resources Control Board  

E-print Network

with water boards to provide data for discussions to overcome sample hold time road-blocks to conducting. Quantify the effect of sample hold time so we can standardize data and assess remote waters. Research Most6/7/2011 1 Bacteria Holding Time and DegradationBacteria Holding Time and Degradation Presented

Tate, Kenneth

137

Cullin 3 mediates SRC-3 ubiquitination and degradation to control the retinoic acid response  

PubMed Central

SRC-3 is an important coactivator of nuclear receptors including the retinoic acid (RA) receptor ?. Most of SRC-3 functions are facilitated by changes in the posttranslational code of the protein that involves mainly phosphorylation and ubiquitination. We recently reported that SRC-3 is degraded by the proteasome in response to RA. Here, by using an RNAi E3-ubiquitin ligase entry screen, we identified CUL-3 and RBX1 as components of the E3 ubiquitin ligase involved in the RA-induced ubiquitination and subsequent degradation of SRC-3. We also show that the RA-induced ubiquitination of SRC-3 depends on its prior phosphorylation at serine 860 that promotes binding of the CUL-3–based E3 ligase in the nucleus. Finally, phosphorylation, ubiquitination, and degradation of SRC-3 cooperate to control the dynamics of transcription. In all, this process participates to the antiproliferative effect of RA. PMID:22147914

Ferry, Christine; Gaouar, Samia; Fischer, Benoit; Boeglin, Marcel; Paul, Nicodeme; Samarut, Eric; Piskunov, Aleksandr; Pankotai-Bodo, Gabriella; Brino, Laurent; Rochette-Egly, Cecile

2011-01-01

138

10 CFR 74.41 - Nuclear material control and accounting for special nuclear material of moderate strategic...  

Code of Federal Regulations, 2010 CFR

...false Nuclear material control and accounting for special nuclear material of moderate...CONTINUED) MATERIAL CONTROL AND ACCOUNTING OF SPECIAL NUCLEAR MATERIAL Special...41 Nuclear material control and accounting for special nuclear material of...

2010-01-01

139

10 CFR 74.31 - Nuclear material control and accounting for special nuclear material of low strategic significance.  

Code of Federal Regulations, 2010 CFR

...false Nuclear material control and accounting for special nuclear material of low...CONTINUED) MATERIAL CONTROL AND ACCOUNTING OF SPECIAL NUCLEAR MATERIAL Special...31 Nuclear material control and accounting for special nuclear material of...

2010-01-01

140

Attitudinal Effects of Degrading Themes and Sexual Explicitness in Video Materials  

Microsoft Academic Search

This study examined the independent and interactive effects of sexual explicitness and degrading themes toward women on mens' attitudes following exposure to video presentations of male–female interactions. Subjects were 83 male college students who viewed video vignettes under one of four stimulus conditions: (a) sexually explicit\\/degrading, (b) sexually explicit\\/nondegrading, (c) nonexplicit\\/degrading, and (d) nonexplicit\\/nondegrading. Results revealed that men exposed to

Jeffrey A. Golde; Donald S. Strassberg; Charles M. Turner; Kristie Lowe

2000-01-01

141

EVALUATION OF THE RESISTANCE OF A CHLORINATED POLYETHYLENE PROTECTIVE GARMENT MATERIAL TO PERMEATION AND DEGRADATION BY LIQUID CHEMICALS  

EPA Science Inventory

The objectives of the project was to investigate existing permeation and degradation resistance data for chlorinated polyethylene (CPE); to develop a laboratory test plan consistent with American Society for Testing and Materials (ASTM) Standard Test Methods F739-81 and D471-79 r...

142

The synthesis and characterization of aluminum loaded SBA-type materials as catalyst for polypropylene degradation reaction  

Microsoft Academic Search

The performance of pure and aluminum containing SBA-type catalysts prepared using different aluminum sources and different Al\\/Si ratios were investigated in the polypropylene degradation reaction using a thermogravimetric analyzer. For the synthesis of catalysts, aluminum isopropoxide and aluminum sulphate were used as the aluminum sources. Synthesized materials had high surface areas and exhibited nitrogen adsorption isotherms of type IV. EDS

Zeynep Obal?; Naime Asl? Sezgi; Timur Do?u

143

In vitro degradation behavior of a novel bioresorbable composite material based on PLA and a soluble CaP glass  

Microsoft Academic Search

Poly(?-hydroxy acids), and in particular polylactic acid (PLA), are nowadays amongst the most used bioabsorbable materials. However, this polymer may not meet some application requirements due to inadequate mechanical properties and or its degradation characteristics. A possible strategy to tackle this problem is the incorporation of an inorganic phase into the polymeric matrix. In this work a new fully biodegradable

M. Navarro; M. P. Ginebra; J. A. Planell; C. C. Barrias; M. A. Barbosa

2005-01-01

144

mRNA degradation controls differentiation state-dependent differences in transcript and splice variant abundance  

PubMed Central

Expression profiling experiments usually provide a static snapshot of messenger RNA (mRNA) levels. Improved understanding of the dynamics of mRNA synthesis and degradation will aid the development of sound bioinformatic models for control of gene expression. We studied mRNA stability in proliferating and differentiated myogenic cells using whole-genome exon arrays and reported the decay rates (half life) for ?7000 mRNAs. We showed that the stability of many mRNAs strongly depends on the differentiation status and contributes to differences in abundance of these mRNAs. In addition, alternative splicing turns out to be coupled to mRNA degradation. Although different splice forms may be produced at comparable levels, their relative abundance is partly determined by their different stabilities in proliferating and differentiated cells. Where the 3?-untranslated region (3?-UTR) was previously thought to contain most RNA stabilizing and destabilizing elements, we showed that this also holds for transcript isoforms sharing the same 3?-UTR. There are two splice variants in Itga7, of which the isoform with an extra internal exon is highly stable in differentiated cells but preferentially degraded in the cytoplasm of proliferating cells. In conclusion, control of stability and degradation emerge as important determinants for differential expression of mRNA transcripts and splice variants. PMID:20852259

't Hoen, Peter A. C.; Hirsch, Michael; de Meijer, Emile J.; de Menezes, Renee X.; van Ommen, Gert Jan; den Dunnen, Johan T.

2011-01-01

145

Defective in Mitotic Arrest 1 (Dma1) Ubiquitin Ligase Controls G1 Cyclin Degradation*  

PubMed Central

Progression through the G1 phase of the cell cycle is controlled by diverse cyclin-dependent kinases (CDKs) that might be associated to numerous cyclin isoforms. Given such complexity, regulation of cyclin degradation should be crucial for coordinating progression through the cell cycle. In Saccharomyces cerevisiae, SCF is the only E3 ligase known to date to be involved in G1 cyclin degradation. Here, we report the design of a genetic screening that uncovered Dma1 as another E3 ligase that targets G1 cyclins in yeast. We show that the cyclin Pcl1 is ubiquitinated in vitro and in vivo by Dma1, and accordingly, is stabilized in dma1 mutants. We demonstrate that Pcl1 must be phosphorylated by its own CDK to efficiently interact with Dma1 and undergo degradation. A nonphosphorylatable version of Pcl1 accumulates throughout the cell cycle, demonstrating the physiological relevance of the proposed mechanism. Finally, we present evidence that the levels of Pcl1 and Cln2 are independently controlled in response to nutrient availability. This new previously unknown mechanism for G1 cyclin degradation that we report here could help elucidate the specific roles of the redundant CDK-cyclin complexes in G1. PMID:23264631

Hernandez-Ortega, Sara; Bru, Samuel; Ricco, Natalia; Ramirez, Sara; Casals, Nuria; Jimenez, Javier; Isasa, Marta; Crosas, Bernat; Clotet, Josep

2013-01-01

146

Transferrin receptor-like proteins control the degradation of a yeast metal transporter  

PubMed Central

Plasma membrane transporters are often downregulated by their substrates. The yeast manganese transporter Smf1 is subject to two levels of regulation: heavy metals induce its sequestration within the cell, and also its ubiquitination and degradation in the vacuole. Degradation requires Bsd2, a membrane protein with a PPxY motif that recruits the ubiquitin ligase Rsp5, and which has a role in the quality control of membrane proteins, that expose hydrophilic residues to the lipid bilayer. We show that degradation of Smf1 requires in addition one of a pair of related yeast proteins, Tre1 and Tre2, that also contain PPxY motifs. Tre1 can partially inhibit manganese uptake without Bsd2, but requires Bsd2 to induce Smf1 degradation. It has a relatively hydrophilic transmembrane domain and binds to Bsd2. We propose that the Tre proteins specifically link Smf1 to the Bsd2-dependent quality control system. Their luminal domains are related to the transferrin receptor, but these are dispensable for Smf1 regulation. Tre proteins and the transferrin receptors appear to have evolved independently from the same family of membrane-associated proteases. PMID:16456538

Stimpson, Helen E M; Lewis, Michael J; Pelham, Hugh R B

2006-01-01

147

Degradation of the materials of construction in Li-ion batteries  

SciTech Connect

The primary current-collector materials being used in lithium-ion cells are susceptible to environmental degradation: aluminum to pitting corrosion and copper to environmentally assisted cracking. Pitting occurs at the highly oxidizing potentials associated with the positive-electrode charge condition. However, the pitting mechanism is more complex than that typically observed in aqueous systems in that the pits are filled with a mixed metal/oxide product and exist as mounds or nodules on the surface. Electrochemical impedance spectroscopy was shown to be an effective analytical tool for quantifying and verifying aluminum corrosion behavior. Two fluorocarbon-based coatings were shown to improve the resistance of Al to pitting attack. Detailed x-ray photoelectron spectroscopy (XPS) surface analyses showed that there was very little difference in the films observed after simple immersion in either PC:DEC or EC:DMC electrolytes versus those following electrical cycling. Li and P are the predominant surface species. Finally, environmental cracking of copper can occur at or near the lithium potential and only if specific metallurgical conditions exist (work-hardening and large grain size).

Braithwaite, J.W.; Gonzales, A.; Lucero, S.J. [and others

1997-03-01

148

Enzymes for Degradation of Energetic Materials and Demilitarization of Explosives Stockpiles - SERDP Annual (Interim) Report, 12/98  

SciTech Connect

The current stockpile of energetic materials requiring disposal contains about half a million tons. Through 2001, over 2.1 million tons are expected to pass through the stockpile for disposal. Safe and environmentally acceptable methods for disposing of these materials are needed. This project is developing safe, economical, and environmentally sound processes using biocatalyst (enzymes) to degrade energetic materials and to convert them into economically valuable products. Alternative methods for destroying these materials are hazardous, environmentally unacceptable, and expensive. These methods include burning, detonation, land and sea burial, treatment at high temperature and pressure, and treatment with harsh chemicals. Enzyme treatment operates at room temperature and atmospheric pressure in a water solution.

Shah, M.M.

1999-01-18

149

Survey of degradation modes of candidate materials for high-level radioactive-waste disposal containers  

SciTech Connect

Three iron- to nickel-based austenitic alloys (Types 304L and 316L stainless steels and Alloy 825) are being considered as candidate materials for the fabrication of high-level radioactive-waste containers. Waste will include fuel assemblies from reactors as well as high-level waste in borosilicate glass forms, and will be sent to the prospective repository at Yucca Mountain, Nevada. The decay of radionuclides in the repository will result in the generation of substantial heat and in fluences of gamma radiation. Container materials may undergo any of several modes of degradation in this environment, including atmospheric oxidation; uniform aqueous phase corrosion; pitting; crevice corrosion; sensitization and intergranular stress corrosion cracking (IGSCC); and transgranular stress corrosion cracking (TGSCC). This report is an analysis of data relevant to the pitting, crevice corrosion, and stress corrosion cracking (SCC) of the three austenitic candidate alloys. The candidates are compared in terms of their susceptibilities to these forms of corrosion. Although all three candidates have demonstrated pitting and crevice corrosion in chloride-containing environments, Alloy 825 has the greatest resistance to these types of localized corrosion (LC); such resistance is important because pits can penetrate the metal and serve as crack initiation sites. Both Types 304L and 316L stainless steels are susceptible to SCC in acidic chloride media. In contrast, SCC has not been documented in Alloy 825 under comparable conditions. Gamma radiation has been found to enhance SCC in Types 304 and 304L stainless steels, but it has no detectable effect on the resistance of Alloy 825 to SCC. Furthermore, while the effects of microbiologically induced corrosion have been observed for 300-series stainless steels, nickel-based alloys such as Alloy 825 seem to be immune to such problems. 211 refs., 49 figs., 10 tabs.

Farmer, J.C.; Van Konynenburg, R.A.; McCright, R.D. (Lawrence Livermore National Lab., CA (USA)); Bullen, D.B. (Science and Engineering Associates, Inc., Pleasanton, CA (USA))

1988-04-01

150

Regulation of ubiquitin chain initiation to control the timing of substrate degradation.  

PubMed

Processive reactions, such as transcription or translation, often proceed through distinct initiation and elongation phases. The processive formation of polymeric ubiquitin chains can accordingly be catalyzed by specialized initiating and elongating E2 enzymes, but the functional significance for this division of labor has remained unclear. Here, we have identified sequence motifs in several substrates of the anaphase-promoting complex (APC/C) that are required for efficient chain initiation by its E2 Ube2C. Differences in the quality and accessibility of these chain initiation motifs can determine the rate of a substrate's degradation without affecting its affinity for the APC/C, a mechanism used by the APC/C to control the timing of substrate proteolysis during the cell cycle. Based on our results, we propose that initiation motifs and their cognate E2s allow E3 enzymes to exert precise temporal control over substrate degradation. PMID:21700221

Williamson, Adam; Banerjee, Sudeep; Zhu, Xining; Philipp, Isabelle; Iavarone, Anthony T; Rape, Michael

2011-06-24

151

Degradation of stone materials in the archaeological context of the Greek-Roman Theatre in Taormina (Sicily, Italy)  

NASA Astrophysics Data System (ADS)

In the present work results on the degradation phenomena of stone materials in the Ancient Theatre of Taormina, one of the most important Greek-Roman monuments of Sicily, are reported. Artificial stone materials in different conservation conditions were investigated. Samples of salt efflorescences from brick walls and degraded setting mortars were taken from the open gallery in “ summa cavea”. The chemical, physical and structural characterization was performed by means of X-Ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF), both in situ and ex situ. Results showed that the deterioration of stone materials is due to the aggressive action of the environment agents. Soluble salts, such as chlorides, sulphates and nitrates, were found in efflorescence samples. Mortars were affected by a decomposition process induced by sulphates’ attack.

Brai, M.; Casaletto, M. P.; Gennaro, G.; Marrale, M.; Schillaci, T.; Tranchina, L.

2010-09-01

152

Spatial Control of Cell-Mediated Degradation to Regulate Vasculogenesis and Angiogenesis in Hyaluronan Hydrogels  

PubMed Central

Matrix remodeling is crucial for neovascularization, however its utilization to control this process in synthetic biomaterials has been limited. Here, we utilized hyaluronic acid (HA) hydrogels to spatially control cellular remodeling during vascular network formation. Specifically, we exploited a secondary radical polymerization to alter the ability of cells to degrade the hydrogel and utilized it to create spatial patterning using light initiation. We first demonstrated the ability of the hydrogel to either support or inhibit in vitro vasculogenesis of endothelial colony-forming cells (ECFCs) or angiogenesis from ex ovo chorioallantoic membranes. We showed that vascular tube branching and sprouting, which required matrix metalloproteinases (MMPs)-dependent remodeling, could be achieved in hydrogels formed by primary addition-crosslinking only. Although ECFCs expressed higher levels of MMPs in the hydrogels with the secondary radical-crosslinking, the generated kinetic chains disabled cell-mediated remodeling and therefore vascular formation was arrested at the vacuole and lumen stage. We then patterned hydrogels to have regions that either permitted or inhibited cell-mediated degradation during in vitro vasculogenesis or angiogenesis. Our ability to control degradation cues that regulate vascular tube formation is important for the study of vascular biology and the application of synthetic biomaterials in tissue regeneration. PMID:22672833

Hanjaya-Putra, Donny; Wong, Kyle T.; Hirotsu, Kelsey; Khetan, Sudhir; Burdick, Jason A.; Gerecht, Sharon

2012-01-01

153

Quality by design development of brivanib alaninate tablets: degradant and moisture control strategy.  

PubMed

A quality by design approach was applied to the development of brivanib alaninate tablets. Brivanib alaninate, an ester pro-drug, undergoes hydrolysis to its parent compound, BMS-540215. The shelf-life of the tablets is determined by the rate of the hydrolysis reaction. Hydrolysis kinetics in the tablets was studied to understand its dependence on temperature and humidity. The BMS-540215 amount versus time profile was simulated using a kinetic model for the formation of BMS-540215 as function of relative humidity in the environment and a sorption-desorptiom moisture transfer model for the relative humidity inside the package. The combined model was used to study the effect of initial tablet water content on the rate of degradation and to identify a limit for initial tablet water content that results in acceptable level of the degradant at the end of shelf-life. A strategy was established for the moisture and degradant control in the tablet based on the understanding of its stability behavior and mathematical models. The control strategy includes a specification limit on the tablet water content and manufacturing process controls that achieve this limit at the time of tablet release testing. PMID:24780101

Badawy, Sherif I F; Lin, Judy; Gokhale, Madhushree; Desai, Sachin; Nesarikar, Vishwas V; LaMarche, Keirnan R; Subramanian, Ganeshkumar A; Narang, Ajit S

2014-07-20

154

RELIABILITY MODELS OF AGING PASSIVE COMPONENTS INFORMED BY MATERIALS DEGRADATION METRICS TO SUPPORT LONG-TERM REACTOR OPERATIONS  

SciTech Connect

Paper describes a methodology for the synthesis of nuclear power plant service data with expert-elicited materials degradation information to estimate the future failure rates of passive components. This method should be an important resource to long-term plant operations and reactor life extension. Conventional probabilistic risk assessments (PRAs) are not well suited to addressing long-term reactor operations. Since passive structures and components are among those for which replacement can be least practical, they might be expected to contribute increasingly to risk in an aging plant; yet, passives receive limited treatment in PRAs. Furthermore, PRAs produce only snapshots of risk based on the assumption of time-independent component failure rates. This assumption is unlikely to be valid in aging systems. The treatment of aging passive components in PRA presents challenges. Service data to quantify component reliability models are sparse, and this is exacerbated by the greater data demands of age-dependent reliability models. Another factor is that there can be numerous potential degradation mechanisms associated with the materials and operating environment of a given component. This deepens the data problem since risk-informed management of component aging will demand an understanding of the long-term risk significance of individual degradation mechanisms. In this paper we describe a Bayesian methodology that integrates metrics of materials degradation susceptibility with available plant service data to estimate age-dependent passive component reliabilities. Integration of these models into conventional PRA will provide a basis for materials degradation management informed by predicted long-term operational risk.

Unwin, Stephen D.; Lowry, Peter P.; Toyooka, Michael Y.

2012-05-01

155

Phase change material for temperature control and material storage  

NASA Technical Reports Server (NTRS)

A phase change material comprising a mixture of water and deuterium oxide is described, wherein the mole fraction of deuterium oxide is selected so that the mixture has a selected phase change temperature within a range between 0.degree. C. and 4.degree. C. The mixture is placed in a container and used for passive storage and transport of biomaterials and other temperature sensitive materials. Gels, nucleating agents, freezing point depression materials and colorants may be added to enhance the characteristics of the mixture.

Wessling, Jr., Francis C. (Inventor); Blackwood, James M. (Inventor)

2011-01-01

156

An investigation of the degradation of Fluorinated Ethylene Propylene (FEP) copolymer thermal blanketing materials aboard LDEF in the laboratory  

NASA Technical Reports Server (NTRS)

Samples of fluorinated ethylene propylene copolymer thermal blanketing material, recovered from the Long Duration Exposure Facility (LDEF), were investigated to determine the nature and the extent of degradation due to exposure to the low-Earth-orbit environment. Samples recovered from the ram-facing direction of LDEF, which received vacuum-ultraviolet (VUV) radiation and atomic-oxygen impingement, and samples from the trailing edge, which received almost exclusively VUV exposure, were investigated by scanning electron microscopy and atomic force microscopy. The most significant result of this investigation was found on samples that received only VUV exposure. These samples possessed a hard, embrittled surface layer that was absent from the atomic-oxygen exposed sample and from unexposed control samples. This surface layer is believed to be responsible for the 'synergistic' effect between VUV and atomic oxygen. Overall, the investigation revealed dramatically different morphologies for the two samples. The sample receiving both atomic-oxygen and VUV exposure was deeply eroded and had a characteristic 'rolling' surface morphology, while the sample that received only VUV exposure showed mild erosion and a surface morphology characterized by sharp high-frequency peaks. The morphologies observed in the LDEF samples, including the embrittled surface layer, were successfully duplicated in the laboratory.

Stiegman, A. E.; Brinza, David E.; Anderson, Mark S.; Minton, Timothy K.; Laue, Eric G.; Liang, Ranty H.

1991-01-01

157

Nuclear Material Control and Accountability System Effectiveness Tool (MSET)  

SciTech Connect

A nuclear material control and accountability (MC&A) system effectiveness tool (MSET) has been developed in the United States for use in evaluating material protection, control, and accountability (MPC&A) systems in nuclear facilities. The project was commissioned by the National Nuclear Security Administration's Office of International Material Protection and Cooperation. MSET was developed by personnel with experience spanning more than six decades in both the U.S. and international nuclear programs and with experience in probabilistic risk assessment (PRA) in the nuclear power industry. MSET offers significant potential benefits for improving nuclear safeguards and security in any nation with a nuclear program. MSET provides a design basis for developing an MC&A system at a nuclear facility that functions to protect against insider theft or diversion of nuclear materials. MSET analyzes the system and identifies several risk importance factors that show where sustainability is essential for optimal performance and where performance degradation has the greatest impact on total system risk. MSET contains five major components: (1) A functional model that shows how to design, build, implement, and operate a robust nuclear MC&A system (2) A fault tree of the operating MC&A system that adapts PRA methodology to analyze system effectiveness and give a relative risk of failure assessment of the system (3) A questionnaire used to document the facility's current MPC&A system (provides data to evaluate the quality of the system and the level of performance of each basic task performed throughout the material balance area [MBA]) (4) A formal process of applying expert judgment to convert the facility questionnaire data into numeric values representing the performance level of each basic event for use in the fault tree risk assessment calculations (5) PRA software that performs the fault tree risk assessment calculations and produces risk importance factor reports on the facility's MC&A (software widely used in the aerospace, chemical, and nuclear power industries) MSET was peer reviewed in 2007 and validated in 2008 by benchmark testing at the Idaho National Laboratory in the United States. The MSET documents were translated into Russian and provided to Rosatom in July of 2008, and MSET is currently being evaluated for potential application in Russian Nuclear Facilities.

Powell, Danny H [ORNL] [ORNL; Elwood Jr, Robert H [ORNL] [ORNL; Roche, Charles T [ORNL] [ORNL; Campbell, Billy J [ORNL] [ORNL; Hammond, Glenn A [ORNL] [ORNL; Meppen, Bruce W [ORNL] [ORNL; Brown, Richard F [ORNL] [ORNL

2011-01-01

158

Alternative material to mitigate chrome degradation on high volume ArF layers  

NASA Astrophysics Data System (ADS)

One of the objectives of a robust optical proximity correction (OPC) model is to simulate the process variation including 3D mask effects or mask models for different mask blanks. Assuming that the data of different reticle blanks is the same, the wafer data should be a close match for the same OPC model. In order to enhance the robustness of the OPC model, the 3D mask effects need to be reduced. A test of this would be to ensure a close match of the so called fingerprints of different reticle blanks at the wafer level. Features for fingerprint test patterns include "critical dimension through pitch" (CDTP), "inverse CDTP", and "linearity patterns" and critical dimension (CD) difference of disposition structures. In this manuscript the proximity matching of implant layers on chrome on glass (COG) and advance binary reticle blanks will be demonstrated. We will also investigate the influence of reticle blank material including reticle process on isolated and dense features upon the proximity matching for 28 nm high volumes ArF layers such as implant and 2X metal layers. The OPC model verification has been done successfully for both bare wafer and full field wafer for implant layers. There is comparable OPC model for advanced binary and COG reticle. Moreover, the wafer critical dimension uniformity (CDU) results show that advance binary has much better wafer CDU then COG. In spite of higher reticle cost when switching over to advanced binary, there is a considerable cost reduction for the wafer fab which includes a 39% savings in total reticle cost as well as cost reduction due to minimal line holds (LH), wafer reworks and scraps due to Chrome degradation.

Ning, Guoxiang; Gopalakrishnan, Selvi; Thamm, Thomas; Oleynik, Nikolay; Ackmann, Paul; Riviere, Remi; Maelzer, Stephanie; Foong, Yee Mei

2013-09-01

159

Non-isothermal kinetics of degradation of ultra-high molecular mass polyethene composite materials  

Microsoft Academic Search

In the present work, the Coats-Redfern method was used to determine the kinetic parameters and the possible reaction mechanism\\u000a of the thermal degradation of ultra-high molecular mass polyethene and its composites with fiber monocrystals in static air\\u000a at three different heating rates ? 6, 10 and 16 K min?1. The analysis of the results obtained showed that the thermal degradation

Dimitrina Koleva; Atanas Atanassov

2008-01-01

160

Light induced degradation in promising multi-crystalline silicon materials for solar cell fabrication  

Microsoft Academic Search

Light induced degradation (LID) in boron doped Czochralski (Cz) silicon with high oxygen content is known to degrade solar cell efficiency. Multicrystalline Si crystals also have oxygen and use B doping, but LID effects are largely unknown. In this paper, ribbon, Cz, and cast multi-crystalline Si crystals with a resistivity of 1-3 \\/spl Omega\\/cm were investigated for LID. 15-16% efficient

B. Damiani; K. Nakayashiki; D. S. Kim; V. Yelundur; S. Ostapenko; I. Tarasov; A. Rohatgi

2003-01-01

161

Virtual earthquake engineering laboratory with physics-based degrading materials on parallel computers  

NASA Astrophysics Data System (ADS)

For the last few decades, we have obtained tremendous insight into underlying microscopic mechanisms of degrading quasi-brittle materials from persistent and near-saintly efforts in laboratories, and at the same time we have seen unprecedented evolution in computational technology such as massively parallel computers. Thus, time is ripe to embark on a novel approach to settle unanswered questions, especially for the earthquake engineering community, by harmoniously combining the microphysics mechanisms with advanced parallel computing technology. To begin with, it should be stressed that we placed a great deal of emphasis on preserving clear meaning and physical counterparts of all the microscopic material models proposed herein, since it is directly tied to the belief that by doing so, the more physical mechanisms we incorporate, the better prediction we can obtain. We departed from reviewing representative microscopic analysis methodologies, selecting out "fixed-type" multidirectional smeared crack model as the base framework for nonlinear quasi-brittle materials, since it is widely believed to best retain the physical nature of actual cracks. Microscopic stress functions are proposed by integrating well-received existing models to update normal stresses on the crack surfaces (three orthogonal surfaces are allowed to initiate herein) under cyclic loading. Unlike the normal stress update, special attention had to be paid to the shear stress update on the crack surfaces, due primarily to the well-known pathological nature of the fixed-type smeared crack model---spurious large stress transfer over the open crack under nonproportional loading. In hopes of exploiting physical mechanism to resolve this deleterious nature of the fixed crack model, a tribology-inspired three-dimensional (3d) interlocking mechanism has been proposed. Following the main trend of tribology (i.e., the science and engineering of interacting surfaces), we introduced the base fabric of solid particle-soft matrix to explain realistic interlocking over rough crack surfaces, and the adopted Gaussian distribution feeds random particle sizes to the entire domain. Validation against a well-documented rough crack experiment reveals promising accuracy of the proposed 3d interlocking model. A consumed energy-based damage model has been proposed for the weak correlation between the normal and shear stresses on the crack surfaces, and also for describing the nature of irrecoverable damage. Since the evaluation of the consumed energy is directly linked to the microscopic deformation, which can be efficiently tracked on the crack surfaces, the proposed damage model is believed to provide a more physical interpretation than existing damage mechanics, which fundamentally stem from mathematical derivation with few physical counterparts. Another novel point of the present work lies in the topological transition-based "smart" steel bar model, notably with evolving compressive buckling length. We presented a systematic framework of information flow between the key ingredients of composite materials (i.e., steel bar and its surrounding concrete elements). The smart steel model suggested can incorporate smooth transition during reversal loading, tensile rupture, early buckling after reversal from excessive tensile loading, and even compressive buckling. Especially, the buckling length is made to evolve according to the damage states of the surrounding elements of each bar, while all other dominant models leave the length unchanged. What lies behind all the aforementioned novel attempts is, of course, the problem-optimized parallel platform. In fact, the parallel computing in our field has been restricted to monotonic shock or blast loading with explicit algorithm which is characteristically feasible to be parallelized. In the present study, efficient parallelization strategies for the highly demanding implicit nonlinear finite element analysis (FEA) program for real-scale reinforced concrete (RC) structures under cyclic loading are proposed. Quantitat

Cho, In Ho

162

Multilayer films assembled from naturally-derived materials for controlled protein release.  

PubMed

Herein we designed and characterized films composed of naturally derived materials for controlled release of proteins. Traditional drug delivery strategies rely on synthetic or semisynthetic materials or utilize potentially denaturing assembly conditions that are not optimal for sensitive biologics. Layer-by-layer (LbL) assembly of films uses benign conditions and can generate films with various release mechanisms including hydrolysis-facilitated degradation. These use components such as synthetic polycations that degrade into non-natural products. Herein we report the use of a naturally derived, biocompatible and degradable polyanion, poly(?-l-malic acid), alone and in combination with chitosan in an LbL film, whose degradation products of malic acid and chitosan are both generally recognized as safe (GRAS) by the FDA. We have found that films based on this polyanion have shown sustained release of a model protein, lysozyme that can be timed from tens of minutes to multiple days through different film architectures. We also report the incorporation and release of a clinically used biologic, basic fibroblast growth factor (bFGF), which demonstrates the use of this strategy as a platform for controlled release of various biologics. PMID:24825478

Hsu, Bryan B; Hagerman, Samantha R; Jamieson, Kelsey; Veselinovic, Jovana; O'Neill, Nicholas; Holler, Eggehard; Ljubimova, Julia Y; Hammond, Paula T

2014-06-01

163

Instrumented microindentation studies on long-term aged materials: work-hardening exponent and yield ratio as new degradation indicators  

Microsoft Academic Search

Using an instrumented microindentation technique for evaluating tensile properties, the present study was undertaken to determine new mechanical parameters measurable in the field that can indicate time-dependent material degradation. Lab-scale tests performed on a Cr–Ni steel and a Cr–Mo steel, two of the most popular heat-resistant steels for facilities in petrochemical and power plants, showed that the work-hardening exponent and

Jae-il Jang; Yeol Choi; Yun-Hee Lee; Dongil Kwon

2005-01-01

164

Application of item and personnel tracking to materials control  

SciTech Connect

Materials Control techniques are utilized to provide assurance that nuclear materials are being handled properly. In the event that materials are improperly handled or potentially malevolent activities utilizing nuclear materials are initiated, the materials control approach should provide a real-time indication to allow a rapid mitigating response. The appropriate response can range from correcting an inadvertent error to preventing an intentional insider-perpetrated incident. This paper is directed at the use of materials control techniques to deter and detect insider malevolence. 1 fig.

Waddoups, I.G.

1989-01-01

165

Nuclear Material Control and Accountability System Effectiveness Tool (MSET)  

Microsoft Academic Search

A nuclear material control and accountability (MC&A) system effectiveness tool (MSET) has been developed in the United States for use in evaluating material protection, control, and accountability (MPC&A) systems in nuclear facilities. The project was commissioned by the National Nuclear Security Administration's Office of International Material Protection and Cooperation. MSET was developed by personnel with experience spanning more than six

Danny H Powell; Robert H Elwood Jr; Charles T Roche; Billy J Campbell; Glenn A Hammond; Bruce W Meppen; Richard F Brown

2011-01-01

166

Estimating the erosion and degradation performance of ceramic and polymeric insulator materials in high current arc environments  

NASA Astrophysics Data System (ADS)

Modeling the erosion and holdoff degradation performance of various commercially available polymeric and ceramic insulators is addressed. The insulators are tested on a surface discharge switch at about 300 kA in atmospheric air. Test diagnostics include the surface voltage holdoff recovery and the eroded mass loss of the insulator and electrode materials used. The ceramic materials tested include several types of aluminum and magnesium silicates, several alumina and zirconia composites, and aluminum and silicon nitride. The polymeric insulators include polyvinyl chloride, low- and high-molecular-weight polyethylene, polytetrafluoroethylene, polyamide, acetyl, polyamide-imide, and several types of glass-reinforced epoxies, melamines, and phenolics. The test results indicate that the holdoff degradation resistance and erosion rates can be qualitatively predicated by the use of merit figures which are based on the thermochemical properties of the insulator. The holdoff degradation and erosion rates can be improved for some thermoset polymers by a suitable choice of electrode material and/or by the ultraviolet stabilization of the insulator.

Engel, T. G.; Kristiansen, M.; O'Hair, E.; Marx, J. N.

1991-01-01

167

Evaluation of Materials During Outdoor Testing Using a Computer-Controlled Test Apparatus.  

National Technical Information Service (NTIS)

Ultraviolet radiation, moisture, heat, and cyclic fatigue are some of the stressors that cause materials to degrade outdoors. Considerable research has addressed the effects of ultraviolet radiation and moisture on the rate of this degradation. An often o...

C. Halpin, C. White, R. S. Williams, S. Lacher

2006-01-01

168

Environmental Degradation of Materials: Surface Chemistry Related to Stress Corrosion Cracking  

NASA Technical Reports Server (NTRS)

Parallel experiments have been performed in order to develop a comprehensive model for stress cracking (SCC) in structural materials. The central objective is to determine the relationship between the activity and selectivity of the microstructure of structural materials to their dissolution kinetics and experimentally measured SCC kinetics. Zinc was chosen as a prototype metal system. The SCC behavior of two oriented single-crystal disks of zinc in a chromic oxide/sodium sulfate solution (Palmerton solution) were determined. It was found that: (1) the dissolution rate is strongly (hkil)-dependent and proportional to the exposure time in the aggressive environment; and (2) a specific slip system is selectively active to dissolution under applied stress and this slip line controls crack initiation and propagation. As a precursor to potential microgrvity experiments, electrophoretic mobility measurements of zinc particles were obtained in solutions of sodium sulfate (0.0033 M) with concentrations of dissolved oxygen from 2 to 8 ppm. The equilibrium distribution of exposed oriented planes as well as their correlation will determine the particle mobility.

Schwarz, J. A.

1985-01-01

169

Degradation of insecticides used for indoor spraying in malaria control and possible solutions  

PubMed Central

Background The insecticide dichloro-diphenyl-trichloroethane (DDT) is widely used in indoor residual spraying (IRS) for malaria control owing to its longer residual efficacy in the field compared to other World Health Organization (WHO) alternatives. Suitable stabilization to render these alternative insecticides longer lasting could provide a less controversial and more acceptable and effective alternative insecticide formulations than DDT. Methods This study sought to investigate the reasons behind the often reported longer lasting behaviour of DDT by exposing all the WHO approved insecticides to high temperature, high humidity and ultra-violet light. Interactions between the insecticides and some mineral powders in the presence of an aqueous medium were also tested. Simple insecticidal paints were made using slurries of these mineral powders whilst some insecticides were dispersed into a conventional acrylic paint binder. These formulations were then spray painted on neat and manure coated mud plaques, representative of the material typically used in rural mud houses, at twice the upper limit of the WHO recommended dosage range. DDT was applied directly onto mud plaques at four times the WHO recommended concentration and on manure plaques at twice WHO recommended concentration. All plaques were subjected to accelerated ageing conditions of 40°C and a relative humidity of 90%. Results The pyrethroids insecticides outperformed the carbamates and DDT in the accelerated ageing tests. Thus UV exposure, high temperature oxidation and high humidity per se were ruled out as the main causes of failure of the alternative insecticides. Gas chromatography (GC) spectrograms showed that phosphogypsum stabilised the insecticides the most against alkaline degradation (i.e., hydrolysis). Bioassay testing showed that the period of efficacy of some of these formulations was comparable to that of DDT when sprayed on mud surfaces or cattle manure coated surfaces. Conclusions Bioassay experiments indicated that incorporating insecticides into a conventional paint binder or adsorbing them onto phosphogypsum can provide for extended effective life spans that compare favourably with DDT's performance under accelerated ageing conditions. Best results were obtained with propoxur in standard acrylic emulsion paint. Similarly, insecticides adsorbed on phosphogypsum and sprayed on cattle manure coated surfaces provided superior lifespans compared with DDT sprayed directly on a similar surface. PMID:22008292

2011-01-01

170

A Tuneable Switch for Controlling Environmental Degradation of Bioplastics: Addition of Isothiazolinone to Polyhydroxyalkanoates  

PubMed Central

Controlling the environmental degradation of polyhydroxybutyrate (PHB) and polyhydroxyvalerate (P(HB-co-HV)) bioplastics would expand the range of their potential applications. Combining PHB and P(HB-co-HV) films with the anti-fouling agent 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOI, <10% w/w) restricted microbial colonisation in soil, but did not significantly affect melting temperature or the tensile strength of films. DCOI films showed reduced biofouling and postponed the onset of weight loss by up to 100 days, a 10-fold increase compared to unmodified films where the microbial coverage was significant. In addition, the rate of PHA-DCOI weight loss, post-onset, reduced by about 150%; in contrast a recorded weight loss of only 0.05% per day for P(HB-co-HV) with a 10% DCOI loading was observed. This is in stark contrast to the unmodified PHB film, where a recorded weight loss of only 0.75% per day was made. The ‘switch’ that initiates film weight loss, and its subsequent reduced rate, depended on the DCOI loading to control biofouling. The control of biofouling and environmental degradation for these DCOI modified bioplastics increases their potential use in biodegradable applications. PMID:24146779

Woolnough, Catherine Anne; Yee, Lachlan Hartley; Charlton, Timothy Stuart; Foster, Leslie John Ray

2013-01-01

171

Relationship between bacterial diversity and function under biotic control: the soil pesticide degraders as a case study  

PubMed Central

In soil, the way biotic parameters impact the relationship between bacterial diversity and function is still unknown. To understand these interactions better, we used RNA-based stable-isotope probing to study the diversity of active atrazine-degrading bacteria in relation to atrazine degradation and to explore the impact of earthworm-soil engineering with respect to this relationship. Bulk soil, burrow linings and earthworm casts were incubated with 13C-atrazine. The pollutant degradation was quantified by liquid chromatography–mass spectrometry for 8 days, whereas active atrazine degraders were identified at 2 and 8 days by sequencing the 16S ribosomal RNA in the 13C-RNA fractions from the three soil microsites. An original diversity of atrazine degraders was found. Earthworm soil engineering greatly modified the taxonomic composition of atrazine degraders with dominance of ?-, ?- and ?-proteobacteria in burrow linings and of Actinobacteria in casts. Earthworm soil bioturbation increased the ?-diversity of atrazine degraders over the soil microsites generated. Atrazine degradation was enhanced in burrow linings in which primary atrazine degraders, closely related to Pelomonas aquatica, were detected only 2 days after atrazine addition. Atrazine degradation efficiency was not linearly related to the species richness of degraders but likely relied on keystone species. By enhancing soil heterogeneity, earthworms sustained high phylogenetic bacterial diversity and exerted a biotic control on the bacterial diversity–function relationships. Our findings call for future investigations to assess the ecological significance of biotic controls on the relationships between diversity and function on ecosystem properties and services (for example, soil detoxification) at larger scales. PMID:21160539

Monard, Cecile; Vandenkoornhuyse, Philippe; Le Bot, Barbara; Binet, Francoise

2011-01-01

172

Thermochromic Indicator Materials with Controlled Reversibility.  

National Technical Information Service (NTIS)

A thermal indicator material which comprises a plurality of polythiophenes having a second low temperature color and a high temperature color. The polythiophenes are structured and arranged to exhibit a color change from the second low temperature color t...

B. Lucht, W. B. Euler, Y. Wang

2004-01-01

173

Advanced diffusion studies with isotopically controlled materials  

SciTech Connect

The use of enriched stable isotopes combined with modern epitaxial deposition and depth profiling techniques enables the preparation of material heterostructures, highly appropriate for self- and foreign-atom diffusion experiments. Over the past decade we have performed diffusion studies with isotopically enriched elemental and compound semiconductors. In the present paper we highlight our recent results and demonstrate that the use of isotopically enriched materials ushered in a new era in the study of diffusion in solids which yields greater insight into the properties of native defects and their roles in diffusion. Our approach of studying atomic diffusion is not limited to semiconductors and can be applied also to other material systems. Current areas of our research concern the diffusion in the silicon-germanium alloys and glassy materials such as silicon dioxide and ion conducting silicate glasses.

Bracht, Hartmut A.; Silvestri, Hughes H.; Haller, Eugene E.

2004-11-14

174

Impedance Spectroscopy for Manufacturing Control of Material Physical Properties  

E-print Network

Impedance Spectroscopy for Manufacturing Control of Material Physical Properties Xiaobei Li for online process control in manufacturing industries. Impedance spectroscopy is a powerful sensing tool investigation in this thesis involve moisture content sensing in food and pharmaceutical products, and hardness

Mamishev, Alexander

175

Survey of degradation modes of candidate materials for high-level radioactive-waste disposal containers; Overview  

SciTech Connect

Three iron- to nickel-based austenitic alloys and three copper-based alloys are being considered as candidate materials for the fabrication of high-level radioactive-waste disposal containers. The austenitic alloys are Types 304L and 316L stainless steels and the high-nickel material Alloy 825. The copper-based alloys are CDA 102 (oxygen-free copper), CDA 613 (Cu-7Al), and CDA 715 (Cu-30Ni). Waste in the forms of both spent fuel assemblies from reactors and borosilicate glass will be sent to the prospective repository at Yucca Mountain, Nevada. The decay of radionuclides will result in the generation of substantial heat and gamma radiation. Container materials may undergo any of several modes of degradation in this environment, including undesirable phase transformations due to a lack of phase stability; atmospheric oxidation; general aqueous corrosion; pitting; crevice corrosion; intergranular stress corrosion cracking; and transgranular stress corrosion cracking. Problems specific to welds, such as hot cracking, may also occur. A survey of the literature has been prepared as part of the process of selecting, from among the candidates, a material that is adequate for repository conditions. The modes of degradation are discussed in detail in the survey to determine which apply to the candidate alloys and the extent to which they may actually occur. The eight volumes of the survey are summarized in Sections 1 through 8 of this overview. The conclusions drawn from the survey are also given in this overview.

Farmer, J.C.; McCright, R.D.; Kass, J.N.

1988-06-01

176

Towards programmable materials : tunable material properties through feedback control of conducting polymers  

E-print Network

Mammalian skeletal muscle is an amazing actuation technology that can controllably modify its force and position outputs as well as its material properties such as stiffness. Unlike muscle, current engineering materials ...

Wiedenman, Nathan Scott

2008-01-01

177

Materials control and accounting (MC and A): the evolutionary pressures  

SciTech Connect

Nuclear materials control and accounting systems are subject to pressures of both regulatory and institutional natures. This fact, coupled with the emergence of new technology, is causing evolutionary changes in materials control and accounting systems. These changes are the subject of this paper.

Shipley, J.P.

1983-01-01

178

Deterministic control of ferroelastic switching in multiferroic materials  

E-print Network

Deterministic control of ferroelastic switching in multiferroic materials N. Balke1 *, S. Choudhury. Kalinin1,6 Multiferroic materials showing coupled electric, magnetic and elastic orderings provide control of non-ferroelectric order parameters in multiferroics has been elusive. Here, we demonstrate

Chen, Long-Qing

179

Systematic control of nonmetallic materials for improved fire safety  

NASA Technical Reports Server (NTRS)

The elements of a systematic fire safety program are summarized and consist of fire safety criteria, design considerations, testing of materials, development of nonmetallic materials, nonmetallic materials information systems, design reviews, and change control. The system described in this report was developed for the Apollo spacecraft. The system can, however, be tailored to many industrial, commercial, and military activities.

1972-01-01

180

Remote inhibition of polymer degradation.  

SciTech Connect

Polymer degradation has been explored on the basis of synergistic infectious and inhibitive interaction between separate materials. A dual stage chemiluminescence detection system with individually controlled hot stages was applied to probe for interaction effects during polymer degradation in an oxidizing environment. Experimental confirmation was obtained that volatile antioxidants can be transferred over a relatively large distance. The thermal degradation of a polypropylene (PP) sample receiving traces of inhibitive antioxidants from a remote source is delayed. Similarly, volatiles from two stabilized elastomers were also capable of retarding a degradation process remotely. This observation demonstrates inhibitive cross-talk as a novel interactive phenomenon between different polymers and is consequential for understanding general polymer interactions, fundamental degradation processes and long-term aging effects of multiple materials in a single environment.

Clough, Roger Lee; Celina, Mathias Christopher

2005-08-01

181

Sorption and degradation of selected five endocrine disrupting chemicals in aquifer material  

Microsoft Academic Search

Sorption and degradation of the five selected endocrine disrupting chemicals (EDCs) including bisphenol A (BPA), 17?-estradiol (E2), 17?-ethynylestradiol (EE2), 4-tert-octylphenol (4-t-OP) and 4-n-nonylphenol (4-n-NP) have been investigated in the laboratory using sediment and groundwater from an aquifer in Bolivar, South Australia. The sorption coefficients measured on the sediment were in the following order: 4-n-NP>4-t-OP>EE2>E2>BPA. The sorption coefficients (Kf values) for

Guang-Guo Ying; Rai S Kookana; Peter Dillon

2003-01-01

182

Factors controlling the abiotic photo-degradation of monomethylmercury in surface waters  

NASA Astrophysics Data System (ADS)

Photo-decomposition is among the most important mechanisms responsible for degrading monomethylmercury (MMHg) in aquatic systems, but this process is not fully understood. We investigated the relative importance of different factors in controlling the rate of MMHg photo-decomposition in surface waters in experiments using DOM isolated from natural waters. We found no evidence of net abiotic production of MMHg in any dark or light exposed treatments. The average (mean ± s.d.) MMHg photo-decomposition rate constant for all light exposed samples using DOM concentrated from three coastal wetlands was 0.0099 ± 0.0020 E-1m2 (range of 0.006-0.015 E-1m2) when expressed in photon flux from 330-700 nm. This was roughly 3-fold higher than the average MMHg photo-decomposition rate constant in coastal seawater of 0.0032 ± 0.0010 E-1m2. MMHg photo-degradation was highly wavelength dependent. The ratio of MMHg photo-decomposition rate constants, with respect to photon flux, was 400:37:1 for UVB:UVA:PAR. However, when integrated across the entire water column over which MMHg photo-demethylation occurs, PAR was responsible for photo-degrading more MMHg than UVB and UVA combined in the three wetland sites because of the more rapid attenuation of UV light with depth. MMHg half-lives in the wetlands were calculated for the upper 250 cm where photo-degradation occurred, and ranged from 7.6 to 20 days under typical summer sunlight conditions at 37°N. Rates of MMHg photo-decomposition decreased with increasing salinity, and were 27% higher at a salinity of 5 than those at a salinity of 25. This difference could not be accounted for by changes in the complexation of MMHg by DOM and chloride. Differences in MMHg photo-degradation rate constants of up to 18% were measured between treatments using DOM concentrated from three different wetlands. Surprisingly, increasing DOM concentration from 1.5 to 11.3 mg OC L-1 had only a small (6%) effect on MMHg photo-decomposition, which was much smaller than the 34% decrease predicted due to the attenuation of light at the higher DOM levels. This suggests that DOM plays an important role in MMHg photo-decomposition apart from mediating light levels and MMHg complexation. Experiments employing various scavengers implied that singlet oxygen and hydroxyl radicals were not involved in the photo-degradation of MMHg in the natural waters used. Varying concentrations of Fe, Cu, and Mn had only small (?11%) effects on rates of MMHg photo-decomposition, and relatively high rates were measured in high purity water with no trace metals or DOM. These results demonstrate that MMHg photo-decomposition can occur via pathways not involving Fe, the photo-Fenton reaction, nitrate photolysis, or thiol complexation. Taken with previous studies, multiple reaction pathways appear to exist, and their importance varies as a function of water chemistry and light wavelength.

Black, Frank J.; Poulin, Brett A.; Flegal, A. Russell

2012-05-01

183

Controllable spontaneous decay at material wedges  

SciTech Connect

We show that the de-excitation process of a dipole emitter can be altered controllably when it is embedded in a dielectric wedge of an arbitrary angle 0<{phi}{sub 0}{<=}2{pi}. We focus here on the case of a dielectric wedge bounded by a perfect conductor and show that the de-excitation process for different wedges, distinguished by {phi}{sub 0}, displays a wide range of features. Besides the dependence on the emitter location at the narrow end, the de-excitation process exhibits a strong dipole orientational dependence, suggesting that the system might serve as a qubit in a controllable scalable hardware architecture for the purpose of quantum information processing.

Skipsey, S. C.; Babiker, M. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Al-Amri, M. [Department of Physics, King Khalid Univeristy, P.O. Box 9003, Abha (Saudi Arabia); Juzeliunas, G. [Institute of Theoretical Physics and Astronomy of Vilnius University, A. Gostauto 12, 01108 Vilnius (Lithuania)

2006-01-15

184

Kinetics of microbial degradation of vascular plant material in two wetland ecosystems  

Microsoft Academic Search

Vascular plant decomposition was followed during two different years in one freshwater and one marine wetland in southeastern Georgia, USA, using a modified litterbag technique. Chemical analysis of plant material revealed different rates of decomposition for different components of the plant material (soluble components, a-cellulose, hemicellulose, and lignin) and, further, that rates of decomposition of each component changed over time,

Mary Ann Moran; Ronald Benner; Robert E. Hodson

1989-01-01

185

ENZYMES FOR DEGRADATION OF ENERGETIC MATERIALS AND DEMILITARIZATION OF EXPLOSIVES STOCKPILES, SERDP ANNUAL (INTERIM) REPORT  

EPA Science Inventory

The current stockpile of energetic materials requiring disposal contains about half a million tons. Through 2001. over 2.1 million tons are expected to pass through the stockpile for disposal. Safe and environmentally acceptable methods for disposing of these materials are needed...

186

Study of Micro and Nano Scale Features in the Fabrication, Performance, and Degradation of Advanced Engineering Materials  

NASA Astrophysics Data System (ADS)

Increasingly, modern engineering materials are designed on a micron or nano scale to fulfill a given set of requirements or to enhance the material's performance. In this dissertation several such materials will be studied including catalyst particles for carbon nanotube (CNT) growth by use of atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS), multi walled carbon nanotubes (MWNTs) by reactor scale modeling, hermetic carbon coatings by focused ion beam/ scanning electron microscopy (FIB/SEM) and Fourier transform infrared spectroscopy (FTIR) the latter of which was performed by Andrei Stolov at OFS Specialty Photonics Division (Avon, CT), and Ni/Yttria stabilized zirconia (YSZ) solid oxide fuel cell (SOFC) anodes using X-ray nanotomography (XNT) and X-ray fluorescence (XRF) the second of which was performed by Barry Lai at APS (Argonne National Lab, IL). For each material, a subset of the material properties will be looked at to determine how the selected property affects either the fabrication, performance, or degradation of the material. Following the analysis of these materials, it was found that although the materials are different, the study of micron and nano scale features has many related traits. X-rays and electrons are frequently used to examine nanoscale structures, numerical study can be exploited to expedite measurements and extract additional information from experiments, and the study of these requires knowledge across many scientific fields. As a product of this research, detailed information about all of the materials studied has been contributed to the scientific literature including size dependance information about the oxidation states of nanometer size iron particles, optimal CVD reactor growth conditions for different CNT catalyst particle sizes and number of walls, a technique for rapid measurement of hermetic carbon film thickness, and detailed microstructural detail and sulfur poisoning mapping for Ni/YSZ SOFC anodes.

Lombardo, Jeffrey John

187

Protein degradation and quality control in cells from laforin and malin knockout mice.  

PubMed

Lafora disease is a progressive myoclonus epilepsy caused by mutations in the EPM2A or EPM2B genes that encode a glycogen phosphatase, laforin, and an E3 ubiquitin ligase, malin, respectively. Lafora disease is characterized by accumulation of insoluble, poorly branched, hyperphosphorylated glycogen in brain, muscle, heart, and liver. The laforinmalin complex has been proposed to play a role in the regulation of glycogen metabolism and protein quality control. We evaluated three arms of the protein degradation/ quality control process (the autophago-lysosomal pathway, the ubiquitin-proteasomal pathway, and the endoplasmic reticulum (ER) stress response) in mouse embryonic fibroblasts from Epm2a(-/-), Epm2b(-/-), and Epm2a(-/-) Epm2b(-/-) mice. The levels of LC3-II, a marker of autophagy, were decreased in all knock-out cells as compared with wild type even though they still showed a slight response to starvation and rapamycin. Furthermore, ribosomal protein S6 kinase and S6 phosphorylation were increased. Under basal conditions there was no effect on the levels of ubiquitinated proteins in the knock-out cells, but ubiquitinated protein degradation was decreased during starvation or stress. Lack of malin (Epm2b(-/-) and Epm2a(-/-) Epm2b(-/-) cells) but not laforin (Epm2a(-/-) cells) decreased LAMP1, a lysosomal marker. CHOP expression was similar in wild type and knock-out cells under basal conditions or with ER stress-inducing agents. In conclusion, both laforin and malin knock-out cells display mTOR-dependent autophagy defects and reduced proteasomal activity but no defects in the ER stress response. We speculate that these defects may be secondary to glycogen overaccumulation. This study also suggests a malin function independent of laforin, possibly in lysosomal biogenesis and/or lysosomal glycogen disposal. PMID:24914213

Garyali, Punitee; Segvich, Dyann M; DePaoli-Roach, Anna A; Roach, Peter J

2014-07-25

188

Understanding local degradation of cycled Ni-rich cathode materials at high operating temperature for Li-ion batteries  

NASA Astrophysics Data System (ADS)

We utilize transmission electron microscopy in conjunction with electron energy loss spectroscopy to investigate local degradation that occurs in LixNi0.8Co0.15Al0.05O2 cathode materials (NCA) after 30 cycles with cutoff voltages of 4.3 V and 4.8 V at 55 °C. NCA has a homogeneous crystallographic structure before electrochemical reactions; however, we observed that 30 cycles of charge/discharge reactions induced inhomogeneity in the crystallographic and electronic structures and also introduced porosity particularly at surface area. These changes were more noticeable in samples cycled with higher cutoff voltage of 4.8 V. Effect of operating temperature was further examined by comparing electronic structures of oxygen of the NCA particles cycled at both room temperature and 55 °C. The working temperature has a greater impact on the NCA cathode materials at a cutoff voltage of 4.3 V that is the practical the upper limit voltage in most applications, while a cutoff voltage of 4.8 V is high enough to cause surface degradation even at room temperature.

Hwang, Sooyeon; Kim, Dong Hyun; Chung, Kyung Yoon; Chang, Wonyoung

2014-09-01

189

A New Class of Risk-Importance Measures to Support Reactor Aging Management and the Prioritization of Materials Degradation Research  

SciTech Connect

As the US fleet of light water reactors ages, the risks of operation might be expected to increase. Although probabilistic risk assessment has proven a critical resource in risk-informed regulatory decision-making, limitations in current methods and models have constrained their prospective value in reactor aging management. These limitations stem principally from the use of static component failure rate models (which do not allow the impact of component aging on failure rates to be represented) and a very limited treatment of passive components (which would be expected to have an increasingly significant risk contribution in an aging system). Yet, a PRA captures a substantial knowledge base that could be of significant value in addressing plant aging. In this paper we will describe a methodology and a new class of risk importance measures that allow the use of an existing PRA model to support the management of plant aging, the prioritization of improvements to non-destructive examination and monitoring techniques, and the establishment of research emphases in materials science. This methodology makes use of data resources generated under the USNRC Proactive Management of Materials Degradation program which addresses the anticipated effects of numerous aging degradation mechanisms on a wide variety of component types.

Unwin, Stephen D.; Lowry, Peter P.; Toyooka, Michael Y.

2010-06-07

190

Survey of the degradation modes of candidate materials for high-level radioactive waste disposal containers. Final report  

SciTech Connect

One of the most significant factors impacting the performance of waste package container materials under repository relevant conditions is the thermal environment. This environment will be affected by the areal power density of the repository, which is dictated by facility design, and the dominant heat transfer mechanism at the site. The near-field environment will evolve as radioactive decay decreases the thermal output of each waste package. Recent calculations (Buscheck and Nitao, 1994) have addressed the importance of thermal loading conditions on waste package performance at the Yucca Mountain site. If a relatively low repository thermal loading design is employed, the temperature and relative humidity near the waste package may significantly affect the degradation of corrosion allowance barriers due to moist air oxidation and radiolytically enhanced corrosion. The purpose this report is to present a literature review of the potential degradation modes for moderately corrosion resistant nickel copper and nickel based candidate materials that may be applicable as alternate barriers for the ACD systems in the Yucca Mountain environment. This report presents a review of the corrosion of nickel-copper alloys, summaries of experimental evaluations of oxidation and atmospheric corrosion in nickel-copper alloys, views of experimental studies of aqueous corrosion in nickel copper alloys, a brief review of galvanic corrosion effects and a summary of stress corrosion cracking in these alloys.

Vinson, D.W.; Bullen, D.B. [Iowa State Univ. of Science and Technology, Ames, IA (United States)

1995-09-22

191

HAZARDOUS WASTE DEGRADATION BY WOOD DEGRADING FUNGI  

EPA Science Inventory

The persistence and toxicity of many hazardous waste constituents indicates that the environment has limited capacity to degrade such materials. he competence and presence of degrading organisms significantly effects our ability to treat and detoxify these hazardous waste chemica...

192

The Effect of Degraded Digital Instrumentation and Control systems on Human-system Interfaces and Operator Performance  

SciTech Connect

Integrated digital instrumentation and control (I&C) systems in new and advanced nuclear power plants (NPPs) will support operators in monitoring and controlling the plants. Even though digital systems typically are expected to be reliable, their potential for degradation or failure significantly could affect the operators performance and, consequently, jeopardize plant safety. This U.S. Nuclear Regulatory Commission (NRC) research investigated the effects of degraded I&C systems on human performance and on plant operations. The objective was to develop technical basis and guidance for human factors engineering (HFE) reviews addressing the operator's ability to detect and manage degraded digital I&C conditions. We reviewed pertinent standards and guidelines, empirical studies, and plant operating experience. In addition, we evaluated the potential effects of selected failure modes of the digital feedwater control system of a currently operating pressurized water reactor (PWR) on human-system interfaces (HSIs) and the operators performance. Our findings indicated that I&C degradations are prevalent in plants employing digital systems, and the overall effects on the plant's behavior can be significant, such as causing a reactor trip or equipment to operate unexpectedly. I&C degradations may affect the HSIs used by operators to monitor and control the plant. For example, deterioration of the sensors can complicate the operators interpretation of displays, and sometimes may mislead them by making it appear that a process disturbance has occurred. We used the findings as the technical basis upon which to develop HFE review guidance.

OHara, J.M.; Gunther, B.; Martinez-Guridi, G. (BNL); Xing, J.; Barnes, V. (NRC)

2010-11-07

193

BIFUNCTIONAL ALUMINUN: A PERMEABLE BARRIER MATERIAL FOR THE DEGRADATION OF MTBE  

EPA Science Inventory

Bifunctional aluminum is an innovative remedial material for the treatment of gasoline oxygenates in permeable reactive barriers (PRBs). PRBs represent a promising environmental technology for remediation of groundwater contamination. Although zero-valent metals (ZVM) have been...

194

Degradation modes of nickel-base alternate waste package overpack materials  

Microsoft Academic Search

The suitability of Ti Grade 12 for waste package overpacks has been questioned because of its observed susceptibility to crevice corrosion and hydrogen-assisted crack growth. For this reason, materials have been selected for evaluation as alternatives to Ti Grade 12 for use as waste package overpacks. These alternative materials, which are based on the nickel-chromium-molybdenum (Ni-Cr-Mo) alloy system, are Inconel

Pitman

1988-01-01

195

Process of making porous ceramic materials with controlled porosity  

DOEpatents

A method of making metal oxide ceramic material is disclosed by which the porosity of the resulting material can be selectively controlled by manipulating the sol used to make the material. The method can be used to make a variety of metal oxide ceramic bodies, including membranes, but also pellets, plugs or other bodies. It has also been found that viscous sol materials can readily be shaped by extrusion into shapes typical of catalytic or adsorbent bodies used in industry, to facilitate the application of such materials for catalytic and adsorbent applications.

Anderson, Marc A. (Madison, WI); Ku, Qunyin (Madison, WI)

1993-01-01

196

Hydrophobic and hydrophilic control in polyphosphazene materials  

NASA Astrophysics Data System (ADS)

This thesis is the culmination of several recent studies focused on the surface characterization of polyphosphazenes specifically the properties of water repellency or hydrophobicity. Chapter 1 is a background account of polyphosphazene chemistry and the hydrophobicity of polyphosphazenes. Chapter 2 provides an examination of the role of surface morphology on hydrophobicity. This study deals in depth with the electrospinning of poly[bis(2,2,2-trifluoroethoxy)phosphazene] in tetrahydrofuran. This process yields fiber mats or bead and fiber mats which exhibit roughness in continuous contact with the water droplet (fiber mats) or discontinuous contact (bead and fiber mats). These surface roughness types are compared to spun cast films using water contact angles to measure the air-water-polymer interface. The influence of aromatic moieties and fluorine content on the air-water-polymer interface is examined in Chapter 3. This study examines the influence of fluorine content and aryloxy groups on the hydrophobicity of a polyphosphazene surface via static water contact angle measurements on a goniometer. Polymer surfaces of spun cast and electrospun mats were probed with advancing, receeding, and static water contact angle and dip coated slides of the same materials were also examined with a Langmuir-Blogett trough. Chapter 4 is a description of the environmental plasma surface treatments of polyphosphazenes as a method of functionalizing solid polymer surfaces. The treatment procedure of functionalizing spun cast and electrospun poly[bis(2,2,2-trifluoroethoxy)phosphazene] surfaces with plasma gases of oxygen, nitrogen, methane, and tetrafluoromethane is detailed. The resulting functionalization of the surface is examined with XPS and water contact angle data. In Chapter 5 fluoroalkoxy polyphosphazenes were processed with liquid carbon dioxide into foams. The foams were then tested for flame retardance and hydrophobicity. Appendixes A-C contain studies on moisture sensitive phosphoranimine monomer storage, micelle formation in water from triblock copolymers, and single ion conductive membranes with increased hydrophobicity respectively. Although the appendixes examine polyphosphazene hydrophobic relationships they are not specific to surface hydrophobicity of solids and were not placed in the main text. Appendix A involves the optimization of storage conditions for a phosphoranimine monomer. Conditions examined include room temperature to -80 ºC and dilution with a variety of organic solvents. The micelle formation of A-B-A triblock copolymer of poly[bis(2,2,2-trifluoroethoxy)phosphazene]-poly(propylene-glycol)-poly[bis(2,2,2-trifluoroethoxy)phosphazene] was explored in appendix B. It was determined with light scattering and TEM that hairpin folding of our triblock copolymer allowed micelle formation with the two hydrophobic poly[bis(2,2,2-trifluoroethoxy)phosphazene] blocks facing the hydrophobic core of the micelle. Appendix C details the lithium ion conductivity of poly[norbornene-pendent-cyclotriphosphazene] with sulfonimide and methoxyethoxyethoxy groups attached. These results are then compared with unbound lithium counter ion systems.

Steely, Lee Brent

197

21 CFR 862.3280 - Clinical toxicology control material.  

...2014-04-01 2014-04-01 false Clinical toxicology control material. 862.3280 Section 862...MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Toxicology Test Systems § 862.3280 Clinical...

2014-04-01

198

21 CFR 862.3280 - Clinical toxicology control material.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Clinical toxicology control material. 862.3280 Section 862...MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Toxicology Test Systems § 862.3280 Clinical...

2013-04-01

199

21 CFR 862.3280 - Clinical toxicology control material.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Clinical toxicology control material. 862.3280 Section 862...MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Toxicology Test Systems § 862.3280 Clinical...

2011-04-01

200

Survey of degradation modes of candidate materials for high-level radioactive-waste disposal containers  

SciTech Connect

Three copper-based alloys and three iron- to nickel-based austenitic alloys are being considered as possible materials for fabrication of containers for disposal of high-level radioactive waste. This waste will include spent fuel assemblies from reactors as well as high-level waste in borosilicate glass and will be sent to the prospective site at Yucca Mountain, Nevada, for disposal. The containers must maintain substantially complete containment for at least 300 yr and perhaps as long as 1000 yr. During the first 50 yr after emplacement, they must be retrievable from the disposal site. Shortly after the containers are emplaced in the repository, they will be exposed to high temperatures and high gamma radiation fields from the decay of the high-level waste. This volume surveys the available data on oxidation and corrosion of the iron- to nickel-based austenitic materials (Types 304L and 316L stainless steels and Alloy 825) and the copper-based alloy materials (CDA 102 (oxygen-free copper), CDA 613 (Cu-7Al), and CDA 715 (Cu-30Ni)), which are the present candidates for fabrication of the containers. Studies that provided a large amount of data are highlighted, and those areas in which little data exists are identified. Examples of successful applications of these materials are given. On the basis of resistance to oxidation and general corrosion, the austenitic materials are ranked as follows: Alloy 825 (best), Type 316L stainless steel, and then Type 304L stainless steel (worst). For the copper-based materials, the ranking is as follows: CDA 715 and CDA 613 (both best), and CDA 102 (worst). 110 refs., 30 figs., 13 tabs.

Gdowski, G.E.; Bullen, D.B. (Science and Engineering Associates, Inc., Pleasanton, CA (USA))

1988-08-01

201

Possible Responsibility of Silicone Materials for Degradation of the CO2 Removal System in the International Space Station  

NASA Technical Reports Server (NTRS)

From data concerning the degradation of the CO2 removal system in the International Space Station (ISS) two important features were apparent: (1) The atmosphere within the International Space Station (ISS) contained many organic compounds including alcohols, halocarbons, aldehydes, esters, and ketones, inter alia. Various cyclosiloxanes Dn, hexamethylcyclotrisiloxane (D3) and its higher homologs (D4) and (D5) are also present presumably due to offgassing. (2) Screens within the zeolite-containing canisters, used for the removal of CO2, exhibited partial clogging due to zeolitic fragments (dust) along with "sticky" residues, that in toto significantly reduced the efficiency of the CO2 removal process. Samples of the ISS fresh zeolite, used zeolite, filter clogging zeolite particles and residual polymeric materials were examined using, inter alia, NMR, EM and HRSEM. These data were compared to equivalent samples obtained prior and subsequent to Dn polymerization experiments performed in our laboratories using the clean ISS zeolite samples as catalyst. Polysiloxane materials produced were essentially equivalent in the two cases and the EM images demonstrate a remarkable similarity between the ISS filter zeolite samples and the post-polymerization zeolite material from our experiments. In this regard even the changes in the Al/Si ratio from the virgin zeolite material to the filter samples and the post-polymerization laboratory samples samples is noteworthy. This research was supported by a contract from the Boeing Company

Baeza, Mario; Sharma, Hemant; Borrok, David; Ren, Mingua; Pannell, Keith

2011-01-01

202

The Toxic Materials Control Program at ORNL revisited  

Microsoft Academic Search

For large industrial and research operations, maintaining reasonable control of all toxic materials used in their operations can be a formidable task. A system utilizing cards has been developed which serves a dual purpose, informing the user regarding hazards of a particular material and also facilitating appropriate workplace surveillance during its use. Selected hazard data and spill notification message, if

EUGENE KETCHEN; WALTER PORTER

1980-01-01

203

Application of porous materials for laminar flow control  

NASA Technical Reports Server (NTRS)

Fairly smooth porous materials were elected for study Doweave; Fibermetal; Dynapore; and perforated titanium sheet. Factors examined include: surface smoothness; suction characteristics; porosity; surface impact resistance; and strain compatibility. A laminar flow control suction glove arrangement was identified with material combinations compatible with thermal expansion and structural strain.

Pearce, W. E.

1978-01-01

204

Biodegradability of biodegradable\\/degradable plastic materials under aerobic and anaerobic conditions  

Microsoft Academic Search

A study was conducted on two types of plastic materials, Mater-Bi Novamont (MB) and Environmental Product Inc. (EPI), to assess their biodegradability under aerobic and anaerobic conditions. For aerobic conditions, organic fractions of municipal solid wastes were composted. For the anaerobic process, anaerobic inoculum from a wastewater treatment plant was used. Cellulose filter papers (CFP) were used as a positive

R. Mohee; G. D. Unmar; A. Mudhoo; P. Khadoo

2008-01-01

205

Corrosion and Degradation of Test Materials in the BI-GAS Coal-Gasification Pilot Plant.  

National Technical Information Service (NTIS)

Corrosion monitoring of test materials was conducted in the BI-GAS coal gasification pilot plant from 1976 through 1981. Montana Rosebud subbituminous coal was processed at pressures of 750 psia (5175 kPa). Metals were exposed at low to moderate temperatu...

R. Yurkewycz, R. F. Firestone

1982-01-01

206

Survey of degradation modes of candidate materials for high-level radioactive-waste disposal containers  

SciTech Connect

Three copper-based alloys and three iron- to nickel-based austenitic alloys are being considered as possible materials for fabrication of high-level radioactive-waste disposal containers. The waste will include spent fuel assemblies from reactors as well as high-level waste in borosilicate glass and will be sent to the prospective site at Yucca Mountain, Nevada, for disposal. The copper-based alloy materials are CDA 102 (oxygen-free copper), CDA 613 (Cu-7Al), and CDA 715 (Cu-30Ni). The austenitic materials are Types 304L and 316L stainless steels and Alloy 825. The waste-package containers must maintain substantially complete containment for at least 300 yr and perhaps as long as 1000 yr, and they must be retrievable from the disposal site during the first 50 yr after emplacement. The containers will be exposed to high temperatures and high gamma radiation fields from the decay of high-level waste. This volume surveys the available data on the phase stability of both groups of candidate alloys. The austenitic alloys are reviewed in terms of the physical metallurgy of the iron-chromium-nickel system, martensite transformations, carbide formation, and intermetallic-phase precipitation. The copper-based alloys are reviewed in terms of their phase equilibria and the possibility of precipitation of the minor alloying constituents. For the austenitic materials, the ranking based on phase stability is: Alloy 825 (best), Type 316L stainless steel, and then Type 304L stainless steel (worst). For the copper-based materials, the ranking is: CDA 102 (oxygen-free copper) (best), and then both CDA 715 and CDA 613. 75 refs., 24 figs., 6 tabs.

Bullen, D.B.; Gdowski, G.E. (Science and Engineering Associates, Inc., Pleasanton, CA (USA))

1988-08-01

207

The relationships among biotic and abiotic factors as control soil degradation processes along a Mediterranean pluviometric gradient.  

NASA Astrophysics Data System (ADS)

The shifts to soil properties that resulted from changes in water availability along a pluviometric gradient from humid to semiarid/arid Mediterranean climate were analyzed. The study was carried out at eight experimental sites in southern Spain and assessed the influence of a reduction in annual average rainfall along the pluviometric gradient on various physical, chemical and hydrological properties of the topsoil, and on the biotic characteristics of the environment. The aims were to assess the soil degradation status, and to determine if any of the soil variables studied could be used as soil degradation indicators. For each experimental site the relationships among a series of edaphic, hydrological and biological properties were investigated, and the principal factors affecting soil degradation were determined using principal component analysis. The properties included the clay, silt and sand content; organic matter; retained organic carbon; salinity; cation exchange capacity; structural stability; USLE K factor; bulk density; saturated hydraulic conductivity; soil moisture; the number of vegetal species; and vegetation cover. The results showed that relationships between biotic and abiotic factors controlled the soil degradation status along a pluviometric gradient from wet to semiarid/arid conditions in the Mediterranean area, and therefore the stability of the eco-geomorphological system depends on the dominant factor. A precipitation-based soil degradation threshold of approximately 500 mm/yr was established, as below this level the vegetation is no longer associated with the presence of greater soil moisture content, but adapts to degradation, as evidenced by the appearance of xerophytic species.

Damian Ruiz Sinoga, Jose; Romero Diaz, Asunción

2010-05-01

208

PREDICTING BIOTRANSFORMATIONS IN THE SUBSURFACE: RELATIONSHIP BETWEEN THE ATP (ADENOSINE TRIPHOSPHATE) CONTENT OF SUBSURFACE MATERIAL AND THE CAPACITY OF SUBSURFACE ORGANISMS TO DEGRADE TOLUENE  

EPA Science Inventory

Deeper subsurface material was collected in a manner that prevented contamination by surface microorganisms. This material was analyzed for ATP content, and for its capacity to degrade toluene, a common organic contaminant of ground water originating from release of petroleum pro...

209

Survey of the degradation modes of candidate materials for high-level radioactive waste disposal containers  

SciTech Connect

Oxidation and atmospheric corrosion data suggest that addition of Cr provides the greatest improvement in oxidation resistance. Cr-bearing cast irons are resistant to chloride environments and solutions containing strongly oxidizing constituents. Weathering steels, including high content and at least 0.04% Cu, appear to provide adequate resistance to oxidation under temperate conditions. However, data from long-term, high-temperature oxidation studies on weathering steels were not available. From the literature, it appears that the low alloy steels, plain carbon steels, cast steels, and cast irons con-ode at similar rates in an aqueous environment. Alloys containing more than 12% Cr or 36% Ni corrode at a lower rate than plain carbon steels, but pitting may be worse. Short term tests indicate that an alloy of 9Cr-1Mo may result in increased corrosion resistance, however long term data are not available. Austenitic cast irons show the best corrosion resistance. A ranking of total corrosion performance of the materials from most corrosion resistant to least corrosion resistant is: Austenitic Cast Iron; 12% Cr = 36% Ni = 9Cr-1Mo; Carbon Steel = Low Alloy Steels; and Cast Iron. Since the materials to be employed in the Advanced Conceptual Design (ACD) waste package are considered to be corrosion allowance materials, the austenitic cast irons, high Cr steels, high Ni steels and the high Cr-Mo steels should not be considered as candidates for the outer containment barrier. Based upon the oxidation and corrosion data available for carbon steels, low alloy steels, and cast irons, a suitable list of candidate materials for a corrosion allowance outer barrier for an ACD waste package could include, A516, 2.25%Cr -- 1%Mo Steel, and A27.

Vinson, D.W.; Nutt, W.M.; Bullen, D.B. [Iowa State Univ. of Science and Technology, Ames, IA (United States)

1995-06-01

210

Optical response of strongly absorbing inhomogeneous materials: Application to paper degradation  

NASA Astrophysics Data System (ADS)

In this paper, we present a new noninvasive and nondestructive approach to recover scattering and absorption coefficients from reflectance measurements of highly absorbing and optically inhomogeneous media. Our approach is based on the Yang and Miklavcic theoretical model of light propagation through turbid media, which is a generalization of the Kubelka-Munk theory, extended to accommodate optically thick samples. We show its applications to paper, a material primarily composed of a web of fibers of cellulose, whose optical properties are strongly governed by light scattering effects. Samples studied were ancient and industrial paper sheets, aged in different conditions and highly absorbing in the ultraviolet region. The recovered experimental absorptions of cellulose fibers have been compared to theoretical ab initio quantum-mechanical computational simulations carried out within time-dependent density functional theory. In this way, for each sample, we evaluate the absolute concentration of different kinds of oxidized groups formed upon aging and acting as chromophores causing paper discoloration. We found that the relative concentration of different chromophores in cellulose fibers depends on the aging temperature endured by samples. This clearly indicates that the oxidation of cellulose follows temperature-dependent reaction pathways. Our approach has a wide range of applications for cellulose-based materials, like paper, textiles, and other manufactured products of great industrial and cultural interest, and can potentially be extended to other strongly absorbing inhomogeneous materials.

Missori, M.; Pulci, O.; Teodonio, L.; Violante, C.; Kupchak, I.; Bagniuk, J.; ?ojewska, J.; Conte, A. Mosca

2014-02-01

211

Evaluation of Low-Earth-Orbit Environmental Effects on International Space Station Thermal Control Materials  

NASA Technical Reports Server (NTRS)

Many spacecraft thermal control coatings in low Earth orbit (LEO) can be affected by solar ultraviolet radiation and atomic oxygen. Ultraviolet radiation can darken some polymers and oxides commonly used in thermal control materials. Atomic oxygen can erode polymer materials, but it may reverse the ultraviolet-darkening effect on oxides. Maintaining the desired solar absorptance for thermal control coatings is important to assure the proper operating temperature of the spacecraft. Thermal control coatings to be used on the International Space Station (ISS) were evaluated for their performance after exposure in the NASA Lewis Research Center's Atomic Oxygen-Vacuum Ultraviolet Exposure (AO-VUV) facility. This facility simulated the LEO environments of solar vacuum ultraviolet (VUV) radiation (wavelength range, 115 to 200 nanometers (nm)) and VUV combined with atomic oxygen. Solar absorptance was measured in vacuo to eliminate the "bleaching" effects of ambient oxygen on VUV-induced degradation. The objective of these experiments was to determine solar absorptance increases of various thermal control materials due to exposure to simulated LEO conditions similar to those expected for ISS. Work was done in support of ISS efforts at the requests of Boeing Space and Defense Systems and Lockheed Martin Vought Systems.

Dever, Joyce A.

1998-01-01

212

Role of chemical reactions of arylamine hole transport materials in operational degradation of organic light-emitting diodes  

SciTech Connect

We report that the representative arylamine hole transport materials undergo chemical transformations in operating organic light-emitting diode (OLED) devices. Although the underlying chemical mechanisms are too complex to be completely elucidated, structures of several identified degradation products point at dissociations of relatively weak carbon-nitrogen and carbon-carbon bonds in arylamine molecules as the initiating step. Considering the photochemical reactivities, the bond dissociation reactions of arylamines occur by the homolysis of the lowest singlet excited states formed by recombining charge carriers in the operating OLED device. The subsequent chemical reactions are likely to yield long-lived, stabilized free radicals capable of acting as deep traps--nonradiative recombination centers and fluorescence quenchers. Their presence in the hole transport layer results in irreversible hole trapping and manifests as a positive fixed charge. The extent and localization of chemical transformations in several exemplary devices suggest that the free radical reactions of hole transporting materials, arylamines, can be sufficient to account for the observed luminance efficiency loss and voltage rise in operating OLEDs. The relative bond strengths and excited state energies of OLED materials appear to have a determining effect on the operational stability of OLED devices.

Kondakov, Denis Y. [Eastman Kodak Company, Rochester, New York 14650-2103 (United States)

2008-10-15

213

Photocatalytic degradation of an azo-dye on TiO2/activated carbon composite material.  

PubMed

A sequential adsorption/photocatalytic regeneration process to remove tartrazine, an azo-dye in aqueous solution, has been investigated. The aim ofthis work was to compare the effectiveness of an adsorbent/photocatalyst composite-TiO2 deposited onto activated carbon (AC) - and a simple mixture of powders of TiO2 and AC in same proportion. The composite was an innovative material as the photocatalyst, TiO2, was deposited on the porous surface ofa microporous-AC using metal-organic chemical vapour deposition in fluidized bed. The sequential process was composed of two-batch step cycles: every cycle alternated a step of adsorption and a step of photocatalytic oxidation under ultra-violet (365 nm), at 25 degreeC and atmospheric pressure. Both steps, adsorption and photocatalytic oxidation, have been investigated during four cycles. For both materials, the cumulated amounts adsorbed during four cycles corresponded to nearly twice the maximum adsorption capacities qmax proving the photocatalytic oxidation to regenerate the adsorbent. Concerning photocatalytic oxidation, the degree of mineralization was higher with the TiO2/AC composite: for each cycle, the value of the total organic carbon removal was 25% higher than that obtained with the mixture powder. These better photocatalytic performances involved better regeneration than higher adsorbed amounts for cycles 2, 3 and 4. Better performances with this promising material - TiO2 deposited onto AC - compared with TiO2 powder could be explained by the vicinity of photocatalytic and AC adsorption sites. PMID:24600875

Andriantsiferana, C; Mohamed, E F; Delmas, H

2014-01-01

214

Survey of degradation modes of candidate materials for high-level radioactive-waste disposal containers  

SciTech Connect

Three copper-based alloys, CDA 102 (oxygen-free copper), CDA 613 (Cu-7Al), and CDA 715 (Cu-30Ni), are being considered along with three austenitic candidates as possible materials for fabrication of containers for disposal of high-level radioactive waste. The waste will include spent fuel assemblies from reactors as well as high-level reprocessing wastes in borosilicate glass and will be sent to the prospective repository at Yucca Mountain, Nevada, for disposal. The containers must maintain mechanical integrity for 50 yr after emplacement to allow for retrieval of waste during the preclosure phase of repository operation. Containment is required to be substantially complete for up to 300 to 1000 yr. During the early period, the containers will be exposed to high temperatures and high gamma radiation fields from the decay of high-level waste. The final closure joint will be critical to the integrity of the containers. This volume surveys the available data on the metallurgy of the copper-based candidate alloys and the welding techniques employed to join these materials. The focus of this volume is on the methods applicable to remote-handling procedures in a hot-cell environment with limited possibility of postweld heat treatment. The three copper-based candidates are ranked on the basis of the various closure techniques. On the basis of considerations regarding welding, the following ranking is proposed for the copper-based alloys: CDA 715 (best) > CDA 102 > CDA 613 (worst). 49 refs., 15 figs., 1 tab.

Bullen, D.B.; Gdowski, G.E. (Science and Engineering Associates, Inc., Pleasanton, CA (USA)); Weiss, H. (Lawrence Livermore National Lab., CA (USA))

1988-06-01

215

Predictive modeling of composite material degradation using piezoelectric wafer sensors electromechanical impedance spectroscopy  

NASA Astrophysics Data System (ADS)

The advancement of composite materials in aircraft structures has led to on increased need for effective structural health monitoring (SHM) technologies that are able to detect and assess damage present in composites structures. The work presented in this paper is interested in understanding using self-sensing piezoelectric wafer active sensors (PWAS) to conduct electromechanical impedance spectroscopy (EMIS) in glass fiber reinforced plastic (GFRP) to perform structures health monitoring. PWAS are bonded to the composite material and the EMIS method is used to analyze the changes in the structural resonance and anti-resonance. As the damage progresses in the specimen, the impedance spectrum will change. In addition, multi-physics based finite element method (MP-FEM) is used to model the electromechanical behavior of a free PWAS and its interaction with the host structure on which it is bonded. The MPFEM permits the input and the output variables to be expressed directly in electric terms while the two way electromechanical conversion is done internally in the MP_FEM formulation. To reach the goal of using the EMIS approach to detect damage, several damages models are generated on laminated GFRP structures. The effects of the modeling are carefully studied through experimental validation. A good match has been observed for low and very high frequencies.

Gresil, Matthieu; Yu, Lingyu; Sutton, Mike; Guo, Siming; Pollock, Patrick

2012-04-01

216

Degradation and reuse of radiative thermal protection system materials for the space shuttle  

NASA Technical Reports Server (NTRS)

Three silicide coated columbium alloys and two cobalt alloys were subjected to identical simulated reentry profiling exposures in both static (controlled vacuum leak) and dynamic (hypersonic plasma shear) environments. Primary emphasis in the columbium alloy evaluation was on the Cb752 and C129Y alloys with a lesser amount on FS85. Commercial silicide coatings of the R512E and VH109 formulations were used. The coated specimens were intentionally defected to provide the types of coating flaws that are expected in service. Temperatures were profiled up to peak temperatures of either 2350 F or 2500 F for 15 minutes in each cycle.

Bartlett, E. S.; Maykuth, D. J.; Grinberg, I. M.; Luce, R. G.

1971-01-01

217

Control of radioactive material transport in sodium-cooled reactors  

SciTech Connect

The Radioactivity Control Technology (RCT) program was established by the Department of Energy to develop and demonstrate methods to control radionuclide transport to ex-core regions of sodium-cooled reactors. This radioactive material is contained within the reactor heat transport system with any release to the environment well below limits established by regulations. However, maintenance, repair, decontamination, and disposal operations potentially expose plant workers to radiation fields arising from radionuclides transported to primary system components. This paper deals with radioactive material generated and transported during steady-state operation, which remains after /sup 24/Na decay. Potential release of radioactivity during postulated accident conditions is not discussed. The control methods for radionuclide transport, with emphasis on new information obtained since the last Environmental Control Symposium, are described. Development of control methods is an achievable goal.

Brehm, W.F.

1980-03-17

218

Initiation of polymer degradation via transfer of infectious species.  

SciTech Connect

A novel dual stage chemiluminescence detection system incorporating individually controlled hot stages has been developed and applied to probe for material interaction effects during polymer degradation. Utilization of this system has resulted in experimental confirmation for the first time that in an oxidizing environment a degrading polymer A (in this case polypropylene, PP) is capable of infecting a different polymer B (in this case polybutadiene, HTPB) over a relatively large distance. In the presence of the infectious degrading polymer A, the thermal degradation of polymer B is observed over a significantly shorter time period. Consistent with infectious volatiles from material A initiating the degradation process in material B it was demonstrated that traces (micrograms) of a thermally sensitive peroxide in the vicinity of PP could induce degradation remotely. This observation documents cross-infectious phenomena between different polymers and has major consequences for polymer interactions, understanding fundamental degradation processes and long-term aging effects under combined material exposures.

Clough, Roger Lee; Jones, Gary Dunn; Celina, Mathias Christopher

2005-06-01

219

Saltstone Disposal Facility Mechanically Stabilized Earth Vault Closure Cap Degradation Base Case: Institutional Control To Pine Forest Scenario  

SciTech Connect

As part of the current Saltstone Disposal Facility (SDF) Performance Assessment (PA) revision, the closure cap configuration was reevaluated and closure cap degradation mechanisms and their impact upon infiltration through the closure cap was evaluated for the existing SDF concrete vaults (i.e. vaults 1 and 4) for the base case land use scenario (i.e. institutional control to pine forest scenario) and documented in Phifer and Nelson (2003). The closure cap configuration was modified from a compacted kaolin barrier layer concept to a geosynthetic clay layer (GCL) barrier layer concept. The degradation mechanisms developed included pine forest succession, erosion, and colloidal clay migration. These degradation mechanisms resulted in changes in the hydraulic properties of the closure cap layers and resulting increases in infiltration through the closure cap over time.

Phifer, MA

2004-03-19

220

The influence of Lemna gibba L. on the degradation of organic material in duckweed-covered domestic wastewater  

Microsoft Academic Search

Laboratory scale experiments on duckweed-covered domestic sewage were carried out to determine whether removal of organic material is faster in the presence of duckweed. Performance of systems containing axenic and non-axenic Lemna gibba L., artificial plastic duckweed, air bubbling pumps and a combination of the latter two were compared with a control system without duckweed to find out which role

S Körner; G. B Lyatuu; J. E Vermaat

1998-01-01

221

Material Control and Accountability Experience at the Fuel Conditioning Facility  

SciTech Connect

The Fuel Conditioning Facility (FCF) at the Idaho National Laboratory (INL) treats spent nuclear fuel using an electrometallurgical process that separates the uranium from the fission products, sodium thermal bond, and cladding materials. Material accountancy is necessary at FCF for two reasons: 1) it provides a mechanism for detecting a potential loss of nuclear material for safeguards and security, and 2) it provides a periodic check of inventories to ensure that processes and materials are within control limits. Material Control and Accountability is also a Department of Energy (DOE) requirement (DOE Order 474.1). The FCF employs a computer based Mass Tracking (MTG) System to collect, store, retrieve, and process data on all operations that directly affect the flow of materials through the FCF. The MTG System is important for the operations of the FCF because it supports activities such as material control and accountability, criticality safety, and process modeling. To conduct material control and accountability checks and to monitor process performance, mass balances are routinely performed around the process equipment. The equipment used in FCF for pyro-processing consists of two mechanical choppers and two electro-refiners (the Mark-IV with the accompanying element chopper and Mark-V with the accompanying blanket chopper for processing driver fuel and blanket, respectively), and a cathode processor (used for processing both driver fuel and blanket) and casting furnace (mostly used for processing driver fuel). Performing mass balances requires the measurement of the masses and compositions of several process streams and equipment inventories. The masses of process streams are obtained via in-cell balances (i.e., load cells) that weigh containers entering and leaving the process equipment. Samples taken at key locations are analyzed to determine the composition of process streams and equipment inventories. In cases where equipment or containers cannot be placed on a balance, others methods (e.g., level measurements, volume calibration equations, calculated density via additive volumes) are utilized to measure the inventory mass. This paper will discuss the material control and accountability experience at the FCF after ten-plus years of processing spent nuclear fuel. A particular area of discussion is the calculated electrolyte density via additive volumes and its importance in determining the mass and composition in the FCF electro-refiners for material control and accountability of special nuclear material. (authors)

Vaden, D.; Fredrickson, G.L. [Idaho National Laboratory, Idaho Falls ID 83415 (United States)

2007-07-01

222

?TrCP controls the lysosome-mediated degradation of CDK1, whose accumulation correlates with tumor malignancy.  

PubMed

In mammals, cell cycle progression is controlled by cyclin-dependent kinases, among which CDK1 plays important roles in the regulation of the G2/M transition, G1 progression and G1/S transition. CDK1 is highly regulated by its association to cyclins, phosphorylation and dephosphorylation, changes in subcellular localization, and by direct binding of CDK inhibitor proteins. CDK1 steady-state protein levels are held constant throughout the cell cycle by a coordinated regulation of protein synthesis and degradation. We show that CDK1 is ubiquitinated by the E3 ubiquitin ligase SCF?TrCP and degraded by the lysosome. Furthermore, we found that DNA damage not only triggers the stabilization of inhibitory phosphorylation sites on CDK1 and repression of CDK1 gene expression, but also regulates ?TrCP-induced CDK1 degradation in a cell type-dependent manner. Specifically, treatment with the chemotherapeutic agent doxorubicin in certain cell lines provokes CDK1 degradation and induces apoptosis, whereas in others it inhibits destruction of the protein. These observations raise the possibility that different tumor types, depending on their pathogenic spectrum mutations, may display different sensitivity to ?TrCP-induced CDK1 degradation after DNA damage. Finally, we found that CDK1 accumulation in patients' tumors shows a negative correlation with ?TrCP and a positive correlation with the degree of tumor malignancy. PMID:25149538

Herrero-Ruiz, Joaquín; Mora-Santos, Mar; Giráldez, Servando; Sáez, Carmen; Japón, Miguel A; Tortolero, Maria; Romero, Francisco

2014-09-15

223

?TrCP controls the lysosome-mediated degradation of CDK1, whose accumulation correlates with tumor malignancy  

PubMed Central

In mammals, cell cycle progression is controlled by cyclin-dependent kinases, among which CDK1 plays important roles in the regulation of the G2/M transition, G1 progression and G1/S transition. CDK1 is highly regulated by its association to cyclins, phosphorylation and dephosphorylation, changes in subcellular localization, and by direct binding of CDK inhibitor proteins. CDK1 steady-state protein levels are held constant throughout the cell cycle by a coordinated regulation of protein synthesis and degradation. We show that CDK1 is ubiquitinated by the E3 ubiquitin ligase SCF?TrCP and degraded by the lysosome. Furthermore, we found that DNA damage not only triggers the stabilization of inhibitory phosphorylation sites on CDK1 and repression of CDK1 gene expression, but also regulates ?TrCP-induced CDK1 degradation in a cell type-dependent manner. Specifically, treatment with the chemotherapeutic agent doxorubicin in certain cell lines provokes CDK1 degradation and induces apoptosis, whereas in others it inhibits destruction of the protein. These observations raise the possibility that different tumor types, depending on their pathogenic spectrum mutations, may display different sensitivity to ?TrCP-induced CDK1 degradation after DNA damage. Finally, we found that CDK1 accumulation in patients’ tumors shows a negative correlation with ?TrCP and a positive correlation with the degree of tumor malignancy. PMID:25149538

Herrero-Ruiz, Joaquin; Mora-Santos, Mar; Giraldez, Servando; Saez, Carmen; Japon, Miguel A.; Tortolero, Maria; Romero, Francisco

2014-01-01

224

FINAL REPORT. CONTROL OF BIOLOGICALLY ACTIVE DEGRADATION ZONES BY VERTICAL HETEROGENEITY: APPLICATIONS IN FRACTURED MEDIA  

EPA Science Inventory

The key objective of this research was to determine the distribution of biologically active contaminant degradation zones in a fractured, subsurface medium with respect to vertical heterogeneities. Our expectation was that hydrogeological properties would determine the size, d...

225

Electromagnetic valve for controlling the flow of molten, magnetic material  

DOEpatents

An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell. 5 figs.

Richter, T.

1998-06-16

226

Electromagnetic valve for controlling the flow of molten, magnetic material  

DOEpatents

An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell.

Richter, Tomas (State College, PA)

1998-01-01

227

USP17- and SCF?TrCP-Regulated Degradation of DEC1 Controls the DNA Damage Response.  

PubMed

In response to genotoxic stress, DNA damage checkpoints maintain the integrity of the genome by delaying cell cycle progression to allow for DNA repair. Here we show that the degradation of the basic helix-loop-helix (bHLH) transcription factor DEC1, a critical regulator of cell fate and circadian rhythms, controls the DNA damage response. During unperturbed cell cycles, DEC1 is a highly unstable protein that is targeted for proteasome-dependent degradation by the SCF(?TrCP) ubiquitin ligase in cooperation with CK1. Upon DNA damage, DEC1 is rapidly induced in an ATM/ATR-dependent manner. DEC1 induction results from protein stabilization via a mechanism that requires the USP17 ubiquitin protease. USP17 binds and deubiquitylates DEC1, markedly extending its half-life. Subsequently, during checkpoint recovery, DEC1 proteolysis is reestablished through ?TrCP-dependent ubiquitylation. Expression of a degradation-resistant DEC1 mutant prevents checkpoint recovery by inhibiting the downregulation of p53. These results indicate that the regulated degradation of DEC1 is a key factor controlling the DNA damage response. PMID:25202122

Kim, Jihoon; D'Annibale, Sara; Magliozzi, Roberto; Low, Teck Yew; Jansen, Petra; Shaltiel, Indra A; Mohammed, Shabaz; Heck, Albert J R; Medema, Rene H; Guardavaccaro, Daniele

2014-11-15

228

Pretreatment of lignocellulosic material with fungi capable of higher lignin degradation and lower carbohydrate degradation improves substrate acid hydrolysis and the eventual conversion to ethanol.  

PubMed

Phanerochaete chrysosporium, Pycnoporus cinnabarinus,and fungal isolates RCK-1 and RCK-3 were tested for their lignin degradation abilities when grown on wheat straw (WS) and Prosopis juliflora (PJ) under solid-state cultivation conditions. Fungal isolate RCK-1 degraded more lignin in WS (12.26% and 22.64%) and PJ (19.30% and 21.97%) and less holocellulose in WS (6.27% and 9.39%) and PJ (3.01% and 4.58%) after 10 and 20 days, respectively, than other fungi tested. Phanerochaete chrysosporium caused higher substrate mass loss and degraded more of holocellulosic content (WS: 55.67%; PJ: 48.89%) than lignin (WS: 18.89%; PJ: 20.20%) after 20 days. The fungal pretreatment of WS and PJ with a high-lignin-degrading and low-holocellulose-degrading fungus (fungal isolate RCK-1) for 10 days resulted in (i) reduction in acid load for hydrolysis of structural polysaccharides (from 3.5% to 2.5% in WS and from 4.5% to 2.5% in PJ), (ii) an increase in the release of fermentable sugars (from 30.27 to 40.82 g L(-1) in WS and from 18.18 to 26.00 g L(-1) in PJ), and (iii) a reduction in fermentation inhibitors (total phenolics) in acid hydrolysate of WS (from 1.31 to 0.63 g L(-1)) and PJ (from 2.05 to 0.80 g L(-1)). Ethanol yield and volumetric productivity from RCK-1-treated WS (0.48 g g(-1) and 0.54 g L(-1) h(-1), respectively) and PJ (0.46 g g(-1) and 0.33 g L(-1) h(-1), respectively) were higher than untreated WS (0.36 g g(-1) and 0.30 g L(-1) h(-1), respectively) and untreated PJ (0.42 g g(-1) and 0.21 g L(-1) h(-1), respectively). PMID:18389003

Kuhar, Sarika; Nair, Lavanya M; Kuhad, Ramesh Chander

2008-04-01

229

Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion  

NASA Technical Reports Server (NTRS)

Tailoring the solar absorptivity (alpha(sub s)) and thermal emissivity (epsilon(sub T)) of materials constitutes an innovative approach to solar energy control and energy conversion. Numerous ceramic and metallic materials are currently available for solar absorbance/thermal emittance control. However, conventional metal oxides and dielectric/metal/dielectric multi-coatings have limited utility due to residual shear stresses resulting from the different coefficient of thermal expansion of the layered materials. This research presents an alternate approach based on nanoparticle-filled polymers to afford mechanically durable solar-absorptive and thermally-emissive polymer nanocomposites. The alpha(sub s) and epsilon(sub T) were measured with various nano inclusions, such as carbon nanophase particles (CNPs), at different concentrations. Research has shown that adding only 5 wt% CNPs increased the alpha(sub s) and epsilon(sub T) by a factor of about 47 and 2, respectively, compared to the pristine polymer. The effect of solar irradiation control of the nanocomposite on solar energy conversion was studied. The solar irradiation control coatings increased the power generation of solar thermoelectric cells by more than 380% compared to that of a control power cell without solar irradiation control coatings.

Kang, Jinho; Marshall, I. A.; Torrico, M. N.; Taylor, C. R.; Ely, Jeffry; Henderson, Angel Z.; Kim, J.-W.; Sauti, G.; Gibbons, L. J.; Park, C.; Lowther, S. E.; Lillehei, P. T.; Bryant, R. G.

2012-01-01

230

Shape control of multi-material heterostructures for catalytic applications  

NASA Astrophysics Data System (ADS)

Shape control of nanomaterials has become increasingly important, as many of their physical and chemical properties are highly dependent on morphology. A tremendous amount of effort has been spent in attempt to control these properties through manipulation of size, composition, and shape. Nanocrystal shape control for both single- and multiple-material systems, however, remains largely empirical and still presents a major challenge. In this dissertation, new methods are described for the rational synthetic design of heterostructures with controlled morphology which is essential for tailoring the catalytic properties of these multi-material systems. Catalytic activity and selectivity are governed by the nature of the catalyst surface, making shaped nanocrystals ideal substrates for understanding the influence of surface structure on heterogeneous catalysis at the nanoscale. First, synthetic methods were developed to produce catalytically active platinum nanocrystals with control over their shape and surface chemistry. Initially, the focus was on the removal of strongly-bound surface stabilizing molecules by ligand exchange to give catalytically clean surfaces. However, the presence of foreign ions used as a shape control agent to produce cubic, cuboctahedral, and octahedrally shaped nanocrystals was found to inhibit catalytic activity. In response, a method was developed for the shape control of uniform platinum nanoparticles stabilized by weakly interacting alkylammonium ions in the absence of foreign metal ions, which showed improved activity for ethylene hydrogenation. The next section describes the application of these highly-faceted platinum nanocrystals as nucleation centers for overgrowth of a secondary metal to obtain shape-controlled heterostructures. Seeded growth allows for the use of the surface structure and corresponding chemical identity of a well-defined seed to control nucleation and growth of another material. Cubic platinum seeds can direct the epitaxial overgrowth of palladium to give shape-controlled core-shell type nanocrystals with structure-sensitive catalytic properties. Incorporation of a lattice-mismatched metal such as gold, on the other hand, introduces an element of selectivity leading to the growth of anisotropic binary nanocrystals where both metals are exposed. The development of multi-component nanoparticles represents a new approach for creating smart materials, requiring controlled and selective growth of different materials on a single particle. In the final section, the concept of seeded overgrowth has been extended to include semiconductor nanostructures as seeds, introducing even greater potential for selective overgrowth of metals due to the unique chemical composition of the different crystallographic facets. Platinum and related binary metals were grown with high selectivity on the tips of cadmium sulfide nanorods for catalytic and energy applications.

Habas, Susan Ellen

231

PERFORMANCE TESTING OF SPILL CONTROL DEVICES ON FLOATABLE HAZARDOUS MATERIALS  

EPA Science Inventory

At the U.S. EPA's Oil and Hazardous Materials Simulated Environmental Test Tank (OHMSETT) in Leonardo, New Jersey, from September 1975 through November 1975, the U.S. Environmental Protection Agency (US EPA) and the U.S. Coast Guard evaluated selected oil-spill control equipment ...

232

Human performance: An essential element in materials control and accountability  

SciTech Connect

The importance of the role of human performance in the successful and effective operation of many activities throughout many industries has been well documented. Most closely related to the materials control and accountability area is the work in human factors that has been ongoing in the U.S. nuclear industry since the Three Mile Island Nuclear Power Plant accident in 1979. Research related to the role of human reliability, human-system interface, and organization and management influences has been and is still being conducted to identify ways to enhance the safe and effective operation of nuclear facilities. This paper will discuss these human performance areas and how they relate to the materials control and accountability area. Particular attention will be focussed on the notion of {open_quotes}safety culture{close_quotes} and how it can be defined and measured for understanding the values and attitudes held by individuals working in the materials control area. It is widely believed that the culture of an organization, which reflects the expectations and values of the management of an organization, is a key element to the operation of that organization. The human performance element is one which has not received a great deal of consideration in the materials control and accountability area and yet it will be demonstrated that it is an essential component to ensure the success of safeguards activities.

Haber, S.B.; Allentuck, J.

1996-10-01

233

WindTech TV: Bonus Materials- Machine Control Circuits  

NSDL National Science Digital Library

This section of the Wind Technician TV website provides bonus materials pertaining to machine control circuits. Users can review content on topics like electrical theory, magnetics, ladder diagrams and start-stop interlock example. Clicking on a subtopic will launch a pop up window demonstrating the concept.

2013-07-01

234

Materials Process Design and Control Laboratory Cornell University  

E-print Network

certain process satisfy some specific experimentally determined statistics of grain size distribution. 3D. Rhodes Hall Cornell University Ithaca, NY 14853-3801 Email: bw336@cornell.edu URL: http;Materials Process Design and Control Laboratory Cornell University Primary Development Employ model

Zabaras, Nicholas J.

235

Development of materials and technologies for control of polymer recycling  

Microsoft Academic Search

The movement toward a recycling-based society through the essential development of recyclable materials alongside technologies for controlling recycling is reviewed. Recently, there has been progress in producing various polymers and technologies with the aim of achieving circulative utilization. For example, the upgrade recycling of commodity plastics, selective transformation of engineering plastics, selective depolymerization of various polymers in supercritical fluids, crosslinking–decrosslinking

Haruo Nishida

2011-01-01

236

49 CFR 195.559 - What coating material may I use for external corrosion control?  

Code of Federal Regulations, 2012 CFR

...coating material may I use for external corrosion control? 195.559 Section 195...OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.559 What coating material may I use for external corrosion control? Coating material...

2012-10-01

237

49 CFR 195.559 - What coating material may I use for external corrosion control?  

Code of Federal Regulations, 2011 CFR

...coating material may I use for external corrosion control? 195.559 Section 195...OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.559 What coating material may I use for external corrosion control? Coating material...

2011-10-01

238

49 CFR 195.559 - What coating material may I use for external corrosion control?  

Code of Federal Regulations, 2013 CFR

...coating material may I use for external corrosion control? 195.559 Section 195...OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.559 What coating material may I use for external corrosion control? Coating material...

2013-10-01

239

5 CFR 1312.26 - Control of secret and confidential material.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 false Control of secret and confidential material. 1312.26...Information § 1312.26 Control of secret and confidential material. Classified...establish accountability controls on all Secret material received or produced...

2010-01-01

240

5 CFR 1312.26 - Control of secret and confidential material.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 false Control of secret and confidential material. 1312.26...Information § 1312.26 Control of secret and confidential material. Classified...establish accountability controls on all Secret material received or produced...

2012-01-01

241

5 CFR 1312.26 - Control of secret and confidential material.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 false Control of secret and confidential material. 1312.26...Information § 1312.26 Control of secret and confidential material. Classified...establish accountability controls on all Secret material received or produced...

2013-01-01

242

5 CFR 1312.26 - Control of secret and confidential material.  

... 2014-01-01 false Control of secret and confidential material. 1312.26...Information § 1312.26 Control of secret and confidential material. Classified...establish accountability controls on all Secret material received or produced...

2014-01-01

243

5 CFR 1312.26 - Control of secret and confidential material.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 false Control of secret and confidential material. 1312.26...Information § 1312.26 Control of secret and confidential material. Classified...establish accountability controls on all Secret material received or produced...

2011-01-01

244

78 FR 71532 - Amendments to Material Control and Accounting Regulations and Proposed Guidance for Fuel Cycle...  

Federal Register 2010, 2011, 2012, 2013

...Amendments to Material Control and Accounting Regulations and Proposed Guidance...Facility Material Control and Accounting Plans and Completing the U...regulations for material control and accounting (MC&A) of special...

2013-11-29

245

77 FR 60482 - Regulatory Guide 5.67, Material Control and Accounting for Uranium Enrichment Facilities...  

Federal Register 2010, 2011, 2012, 2013

...Guide 5.67, Material Control and Accounting for Uranium Enrichment Facilities Authorized...5.67, ``Material Control and Accounting for Uranium Enrichment Facilities Authorized...to develop their material control and accounting (MC&A) programs under Title...

2012-10-03

246

78 FR 79328 - Amendments to Material Control and Accounting Regulations and Proposed Guidance for Fuel Cycle...  

Federal Register 2010, 2011, 2012, 2013

...Amendments to Material Control and Accounting Regulations and Proposed Guidance...Facility Material Control and Accounting Plans and Completing the U...guidance on material control and accounting (MC&A) of special...

2013-12-30

247

78 FR 67223 - Proposed Guidance for Fuel Cycle Facility; Material Control and Accounting Plans and Completing...  

Federal Register 2010, 2011, 2012, 2013

...Facility; Material Control and Accounting Plans and Completing NRC Form 327...Amendments to Material Control and Accounting Regulations; Proposed Rules Federal...Facility; Material Control and Accounting Plans and Completing NRC Form...

2013-11-08

248

Simultaneous Control of Ionic and Electronic Conductivity in Materials: Thallium Bromide Case Study  

NASA Astrophysics Data System (ADS)

Achieving simultaneous control of ionic and electronic conductivity in materials is one of the great challenges in solid state ionics. Since these properties are intertwined, optimizing one often results in degrading the other. In this Letter, we propose a method to limit ionic current without impacting the electronic properties of a general class of materials, based on codoping with oppositely charged ions. We describe a set of analyses, based on parameter-free quantum mechanical simulations, to assess the efficacy of the approach and determine optimal dopants. For illustration, we discuss the case of thallium bromide, a wide band gap ionic crystal whose promise as a room-temperature radiation detector has been hampered by ionic migration. We find that acceptors and donors bind strongly with the charged vacancies that mediate ionic transport, forming neutral complexes that render them immobile. Analysis of carrier recombination and scattering by the complexes allows the identification of specific dopants that do not degrade electronic transport in the crystal.

Leão, Cedric R.; Lordi, Vincenzo

2012-06-01

249

Simultaneous control of ionic and electronic conductivity in materials: thallium bromide case study.  

PubMed

Achieving simultaneous control of ionic and electronic conductivity in materials is one of the great challenges in solid state ionics. Since these properties are intertwined, optimizing one often results in degrading the other. In this Letter, we propose a method to limit ionic current without impacting the electronic properties of a general class of materials, based on codoping with oppositely charged ions. We describe a set of analyses, based on parameter-free quantum mechanical simulations, to assess the efficacy of the approach and determine optimal dopants. For illustration, we discuss the case of thallium bromide, a wide band gap ionic crystal whose promise as a room-temperature radiation detector has been hampered by ionic migration. We find that acceptors and donors bind strongly with the charged vacancies that mediate ionic transport, forming neutral complexes that render them immobile. Analysis of carrier recombination and scattering by the complexes allows the identification of specific dopants that do not degrade electronic transport in the crystal. PMID:23004304

Leão, Cedric R; Lordi, Vincenzo

2012-06-15

250

Phase change thermal control materials, method and apparatus  

NASA Technical Reports Server (NTRS)

An apparatus and method for metabolic cooling and insulation of a user in a cold environment. In its preferred embodiment the apparatus is a highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The apparatus can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The apparatus may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the apparatus also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.

Buckley, Theresa M. (Inventor)

2001-01-01

251

Compatibility of refractory materials for nuclear reactor poison control systems  

NASA Technical Reports Server (NTRS)

Metal-clad poison rods have been considered for the control system of an advanced space power reactor concept studied at the NASA Lewis Research Center. Such control rods may be required to operate at temperatures of about 140O C. Selected poison materials (including boron carbide and the diborides of zirconium, hafnium, and tantalum) were subjected to 1000-hour screening tests in contact with candidate refractory metal cladding materials (including tungsten and alloys of tantalum, niobium, and molybdenum) to assess the compatibility of these materials combinations at the temperatures of interest. Zirconium and hafnium diborides were compatible with refractory metals at 1400 C, but boron carbide and tantalum diboride reacted with the refractory metals at this temperature. Zirconium diboride also showed promise as a reaction barrier between boron carbide and tungsten.

Sinclair, J. H.

1974-01-01

252

Evaluation and Selection of Replacement Thermal Control Materials for the Hubble Space Telescope  

NASA Technical Reports Server (NTRS)

The mechanical and optical properties of the metallized Teflon(Registered Trademark) FEP thermal control materials on the Hubble Space Telescope (HST) have degraded over the nearly seven years the telescope has been in orbit. Given the damage to the outer layer of the multi-layer insulation (MLI) that was apparent during the second servicing mission (SM2), the decision was made to replace the outer layer during subsequent servicing missions. A Failure Review Board was established to investigate the damage to the MLI and identify a replacement material. The replacement material had to meet the stringent thermal requirements of the spacecraft and maintain structural integrity for at least ten years. Ten candidate materials were selected and exposed to ten-year HST-equivalent doses of simulated orbital environments. Samples of the candidates were exposed sequentially to low and high energy electrons and protons, atomic oxygen, x-ray radiation, ultraviolet radiation and thermal cycling. Following the exposures, the mechanical integrity and optical properties of the candidates were investigated using Optical Microscopy, Scanning Electron Microscopy (SEM), and a Laboratory Portable Spectroreflectometer (LPSR). Based on the results of these simulations and analyses, the FRB selected a replacement material and two alternates that showed the highest likelihood of providing the requisite thermal properties and surviving for ten years in orbit.q

Townsend, Jacqueline A.; Hansen, Patricia A.; McClendon, Mark W.; Dever, Joyce A.; Triolo, Jack J.

1998-01-01

253

Ground-Based Testing of Replacement Thermal Control Materials for the Hubble Space Telescope  

NASA Technical Reports Server (NTRS)

The mechanical and optical properties of the metallized Teflon FEP thermal control materials on the Hubble Space Telescope (HST) have degraded over the nearly seven years the telescope has been in orbit. Given the damage to the outer layer of the multi-layer insulation (MLI) that was apparent during the second servicing mission (SM2), the decision was made to replace the outer layer during subsequent servicing missions. A Failure Review Board was established to investigate the damage to the MLI and identify a replacement material. The replacement material had to meet the stringent thermal requirements of the spacecraft and maintain mechanical integrity for at least ten years. Ten candidate materials were selected and exposed to ten-year HST-equivalent doses of simulated orbital environments. Samples of the candidates were exposed sequentially to low and high energy electrons and protons, atomic oxygen, x-ray radiation, ultraviolet radiation and thermal cycling. Following the exposures, the mechanical integrity and optical properties of the candidates were investigated using Optical Microscopy, Scanning Electron Microscopy (SEM), a Laboratory Portable Spectroreflectometer (LPSR) and a Lambda 9 Spectroreflectometer. Based on the results of these simulations and analyses, the Failure Review Board selected a replacement material and two alternates that showed the highest likelihood of providing the requisite thermal properties and surviving for ten years in orbit.

Townsend, Jacqueline A.; Hansen, Patricia A.; McClendon, Mark W.; deGroh, Kim K.; Banks, Bruce A.; Triolo, Jack J.

1998-01-01

254

Spoken commands control robot that handles radioactive materials  

SciTech Connect

Several robotic systems have been developed by Los Alamos National Laboratory to handle radioactive material. Because of safety considerations, the robotic system must be under direct human supervision and interactive control continuously. In this paper, we describe the implementation of a voice-recognition system that permits this control, yet allows the robot to perform complex preprogrammed manipulations without the operator's intervention. To provide better interactive control, we connected to the robot's control computer, a speech synthesis unit, which provides audible feedback to the operator. Thus upon completion of a task or if an emergency arises, an appropriate spoken message can be reported by the control computer. The training programming and operation of this commercially available system are discussed, as are the practical problems encountered during operations.

Phelan, P.F.; Keddy, C.; Beugelsdojk. T.J.

1989-01-01

255

Radioactive material inventory control at a waste characterization facility  

SciTech Connect

Due to the recent introduction of more stringent Department of Energy (DOE) regulations and requirements pertaining to nuclear and criticality safety, the control of radioactive material inventory has emerged as an important facet of operations at DOE nuclear facilities. In order to comply with nuclear safety regulations and nuclear criticality requirements, radioactive material inventories at each nuclear facility have to be maintained below limits specified for the facility in its safety authorization basis documentation. Exceeding these radioactive material limits constitutes a breach of the facility`s nuclear and criticality safety envelope and could potentially result in an accident, cause a shut-down of the facility, and bring about imminent regulatory repercussions. The practice of maintaining control of radioactive material, especially sealed and unsealed sources, is commonplace and widely implemented; however, the requirement to track the entire radioactivity inventory at each nuclear facility for the purpose of ensuring nuclear safety is a new development. To meet the new requirements, the Applied Radiation Measurements Department at Oak Ridge National Laboratory (ORNL) has developed an information system, called the {open_quotes}Radioactive Material Inventory System{close_quotes} (RMIS), to track the radioactive material inventory at an ORNL facility, the Waste Examination and Assay Facility (WEAF). The operations at WEAF, which revolve around the nondestructive assay and nondestructive examination of waste and related research and development activities, results in an ever-changing radioactive material inventory. Waste packages and radioactive sources are constantly being brought in or taken out of the facility; hence, use of the RMIS is necessary to ensure that the radioactive material inventory limits are not exceeded.

Yong, L.K.; Chapman, J.A.; Schultz, F.J. [Oak Ridge National Laboratory, TN (United States)

1996-06-01

256

NRC Effort on Regulatory Approaches for Control of Solid Materials  

SciTech Connect

The U.S. Nuclear Regulatory Commission's (NRC's) regulations that set standards for protection of the public against radiation do not currently contain specific requirements for the control of solid materials with small or no amounts of radioactivity. Absent a National standard, NRC routinely evaluates, on a case-by-case basis, licensee requests to release solid materials when they are obsolete or no longer useful during operations, or when the facility is being shut down during decommissioning. As part of its continuing examination regarding the control of solid materials, NRC sponsored and received a report from the National Academies' (NA's) National Research Council that reviewed technical bases, policies, and precedents, and made several recommendations for moving forward on this issue. NRC evaluated the NA report and developed a set of options for proceeding with a process for examining approaches for control of solid materials. This paper explains the option that NRC chose and summarizes NRC's technical basis development and related National and international activities.

Huffert, A. M.

2003-02-27

257

Material and method to dissociate water at controlled rates  

SciTech Connect

A material and method for the decomposition/dissociation of water into hydrogen and oxygen is disclosed. The material comprises an amalgam of an alkali metal, mercury, and aluminum combined with a catalytically effective amount of an alloy comprising platinum and at least one metal selected from the group consisting of germanium, antimony, gallium, thallium, indium, cadmium, bismuth, lead, zinc and tin, and with an extender metal to control the rate of dissociation of the water while being non-reactive with the amalgam during dissociation.

Anderson, E.R.

1982-04-13

258

Nuclear materials control and accountability criteria for upgrades measures  

SciTech Connect

As a result of major political and societal changes in the past several years, methods of nuclear material control may no longer be as effective as in the past in Russia, the Newly Independent States (NIS), and the Baltic States (BS). The objective of the Department of Energy (DOE) Material Protection, Control, and Accounting Program (MPC and A) is to reduce the threat of nuclear proliferation by collaborating with Russia, NIS, and BS governments to promote western-style MPC and A. This cooperation will improve the MPC and A on all weapons useable nuclear materials and will establish a sustainable infrastructure to provide future support and maintenance for these technology-based improvements. Nuclear materials of proliferation concern include materials of the types and quantities that can be most easily and directly used in a nuclear weapon. Sabotage of nuclear material is an event of great concern and potentially disastrous consequences to both the US and the host country. However, sabotage is currently beyond the scope of program direction and cannot be used to justify US-funded MPC and A upgrades. Judicious MPC and A upgrades designed to protect against insider and outsider theft scenarios would also provide addition, although not comprehensive, protection against saboteurs. This paper provides some suggestions to establish consistency in prioritizing system-enhancement efforts at nuclear material facilities. The suggestions in this paper are consistent with DOE policy and directions and should be used as a supplement to any policy directives issued by NN-40, DOE Russia/NIS Task Force.

Erkkila, B.H.; Hatcher, C.R.

1998-11-01

259

Drosophila IAP1-Mediated Ubiquitylation Controls Activation of the Initiator Caspase DRONC Independent of Protein Degradation  

PubMed Central

Ubiquitylation targets proteins for proteasome-mediated degradation and plays important roles in many biological processes including apoptosis. However, non-proteolytic functions of ubiquitylation are also known. In Drosophila, the inhibitor of apoptosis protein 1 (DIAP1) is known to ubiquitylate the initiator caspase DRONC in vitro. Because DRONC protein accumulates in diap1 mutant cells that are kept alive by caspase inhibition (“undead” cells), it is thought that DIAP1-mediated ubiquitylation causes proteasomal degradation of DRONC, protecting cells from apoptosis. However, contrary to this model, we show here that DIAP1-mediated ubiquitylation does not trigger proteasomal degradation of full-length DRONC, but serves a non-proteolytic function. Our data suggest that DIAP1-mediated ubiquitylation blocks processing and activation of DRONC. Interestingly, while full-length DRONC is not subject to DIAP1-induced degradation, once it is processed and activated it has reduced protein stability. Finally, we show that DRONC protein accumulates in “undead” cells due to increased transcription of dronc in these cells. These data refine current models of caspase regulation by IAPs. PMID:21909282

Wang, Shiuan; Srivastava, Mayank; Broemer, Meike; Meier, Pascal; Bergmann, Andreas

2011-01-01

260

Minimization of NBTI Performance Degradation Using Internal Node Control David R. Bild  

E-print Network

for an increase in threshold voltage. These mechanisms lead to an interesting recovery effect; when the stress degradation. However, thanks to the previously de- scribed recovery effect, for circuits experiencing typical. However, many designs employ sleep or clock-gating techniques in order to reduce dynamic power consumption

Dick, Robert

261

Engineering multi-stage nanovectors for controlled degradation and tunable release kinetics  

PubMed Central

Nanovectors hold substantial promise in abating the off-target effects of therapeutics by providing a means to selectively accumulate payloads at the target lesion, resulting in an increase in the therapeutic index. A sophisticated understanding of the factors that govern the degradation and release dynamics of these nanovectors is imperative to achieve these ambitious goals. In this work, we elucidate the relationship that exists between variations in pore size and the impact on the degradation, loading, and release of multistage nanovectors. Larger pored vectors displayed faster degradation and higher loading of nanoparticles, while exhibiting the slowest release rate. The degradation of these particles was characterized to occur in a multi-step progression where they initially decreased in size leaving the porous core isolated, while the pores gradually increased in size. Empirical loading and release studies of nanoparticles along with diffusion modeling revealed that this prolonged release was modulated by the penetration within the porous core of the vectors regulated by their pore size. PMID:23911070

Martinez, Jonathan O.; Chiappini, Ciro; Ziemys, Arturas; Faust, Ari M.; Kojic, Milos; Liu, Xuewu; Ferrari, Mauro; Tasciotti, Ennio

2013-01-01

262

[Characteristics of plasmid pBS271 controlling epsilon-caprolactam degradation by bacteria in the genus Pseudomonas].  

PubMed

Conjugative plasmids control the ability of five Pseudomonas strains isolated from the rectifiers of chemical plants to grow on epsilon-caprolactam as a sole carbon and nitrogen source. All the plasmids have a high molecular mass of their DNA (ca. 300 MDa) and control epsilon-caprolactam degradation at least to succinate. One of the plasmids (pBS271) belongs to the incompatibility group P-2 and suppresses the growth of a broad spectrum of temperate and virulent P. aeruginosa bacteriophages as well as that of some P. putida bacteriophages. PMID:3724565

Boronin, A M; Grishchenkov, V G; Kulakov, L A; Naumova, R P

1986-01-01

263

Development of Tailorable Electrically Conductive Thermal Control Material Systems  

NASA Technical Reports Server (NTRS)

The optical characteristics of surfaces on spacecraft are fundamental parameters in controlling its temperature. Passive thermal control coatings with designed solar absorptance and infrared emittance properties have been developed and been in use for some time. In this total space environment, the coating must be stable and maintain its desired optical properties for the course of the mission lifetime. The mission lifetimes are increasing and in our quest to save weight, newer substrates are being integrated which limit electrical grounding schemes. All of this has already added to the existing concerns about spacecraft charging and related spacecraft failures or operational failures. The concern is even greater for thermal control surfaces that are very large. One way of alleviating such concerns is to design new thermal control material systems (TCMS) that can help to mitigate charging via providing charge leakage paths. The object of this program was to develop two types of passive electrically conductive TCMS.

Deshpande, M. S.; Harada, Y.

1998-01-01

264

Controlling Beryllium Contaminated Material And Equipment For The Building 9201-5 Legacy Material Disposition Project  

SciTech Connect

This position paper addresses the management of beryllium contamination on legacy waste. The goal of the beryllium management program is to protect human health and the environment by preventing the release of beryllium through controlling surface contamination. Studies have shown by controlling beryllium surface contamination, potential airborne contamination is reduced or eliminated. Although there are areas in Building 9201-5 that are contaminated with radioactive materials and mercury, only beryllium contamination is addressed in this management plan. The overall goal of this initiative is the compliant packaging and disposal of beryllium waste from the 9201-5 Legacy Material Removal (LMR) Project to ensure that beryllium surface contamination and any potential airborne release of beryllium is controlled to levels as low as practicable in accordance with 10 CFR 850.25.

Reynolds, T. D.; Easterling, S. D.

2010-10-01

265

Controlled spontaneous emission in erbium-doped microphotonic materials  

Microsoft Academic Search

Erbium is a rare-earth metal that, when incorporated in a solid, can emit light at a wavelength of 1.5 ?m. It plays a key role in current day telecommunication technology as the principle ingredient of optical fiber amplifiers. In this thesis the control of the Er spontaneous emission in three different types of microphotonic materials is described.\\u000a\\u000a\\u000aPart I of

Jeroen Kalkman

2005-01-01

266

Robotic control architecture development for automated nuclear material handling systems  

SciTech Connect

Lawrence Livermore National Laboratory (LLNL) is engaged in developing automated systems for handling materials for mixed waste treatment, nuclear pyrochemical processing, and weapon components disassembly. In support of these application areas there is an extensive robotic development program. This paper will describe the portion of this effort at LLNL devoted to control system architecture development, and review two applications currently being implemented which incorporate these technologies.

Merrill, R.D.; Hurd, R.; Couture, S.; Wilhelmsen, K.

1995-02-01

267

Insider Threat - Material Control and Accountability Mitigation (Presentation)  

SciTech Connect

Why is the insider a concern? There are many documented cases of nuclear material available for sale - there are more insider diversions than outsider attacks and more than 18 documented cases of theft or loss of plutonium or highly enriched uranium. Insider attributes are: have access, has authority, possesses knowledge, works with absence of timeline, can test system, and may act alone or support a team. Material control and accountability (MC&A) is an essential part of an integrated safeguards system. Objectives of MC&A are: (1) Ongoing confirmation of the presence of special nuclear material (SNM) in assigned locations; (2) Prompt investigation of anomalies that may indicate a loss of SNM; (3) Timely and localized detection of loss, diversion, or theft of a goal quantity; (4) Rapid assessment and response to detection alarms; and (5) Timely generation of information to aid in the recovery of SNM in the event of an actual loss, diversion, or theft from the purview of the MC&A system. Control and accountability of material, equipment, and data are essential to minimizing insider threats.

Powell, Danny H [ORNL] [ORNL; Elwood Jr, Robert H [ORNL] [ORNL

2011-01-01

268

Safeguarding nuclear materials in the former Soviet Republics through computerized materials protection, control and accountability  

SciTech Connect

The threat of nuclear weapons proliferation is a problem of global concern. International efforts at nonproliferation focus on preventing acquisition of weapons-grade nuclear materials by unauthorized states, organizations, or individuals. Nonproliferation can best be accomplished through international cooperation in the application of advanced science and technology to the management and control of nuclear materials. Computerized systems for nuclear material protection, control, and accountability (MPC and A) are a vital component of integrated nuclear safeguards programs. This paper describes the progress of scientists in the United States and former Soviet Republics in creating customized, computerized MPC and A systems. The authors discuss implementation of the Core Material Accountability System (CoreMAS), which was developed at Los Alamos National Laboratory by the US Department of Energy and incorporates, in condensed and integrated form, the most valuable experience gained by US nuclear enterprises in accounting for and controlling nuclear materials. The CoreMAS approach and corresponding software package have been made available to sites internationally. CoreMAS provides methods to evaluate their existing systems and to examine advantages and disadvantages of customizing CoreMAS or improving their own existing systems. The sites can also address crucial issues of software assurance, data security, and system performance; compare operational experiences at sites with functioning computerized systems; and reasonably evaluate future efforts. The goal of the CoreMAS project is to introduce facilities at sites all over the world to modern international MPC and A practices and to help them implement effective, modern, computerized MPC and A systems to account for their nuclear materials, and thus reduce the likelihood of theft or diversion. Sites are assisted with MPC and A concepts and the implementation of an effective computerized MPC and A system.

Roumiantsev, A.N.; Ostroumov, Y.A. [Kurchatov Inst. Russian Research Center, Moscow (Russian Federation); Whiteson, R.; Seitz, S.L.; Landry, R.P.; Martinez, B.J.; Boor, M.G.; Anderson, L.K.; Gary, S.P. [Los Alamos National Lab., NM (United States)

1997-11-01

269

Influence of the Piping-material-originated Metal-ion on Cell Degradation of Polymer Electrolyte Fuel Cell  

NASA Astrophysics Data System (ADS)

Influences of metal-ion adulterations into Polymer Electrolyte Fuel Cells (PEFC) were examined on PEFC generation characteristics and structural changes. Cupper and aluminun, novel candidate materials for forthcoming PEFC system, were introduced into polymer electrolyte membranes (PEM) by ion-exchange method as contaminants, and ca. 500-hour generation tests of PEFC cells with these PEMs were conducted in this study. Introduced metal ions were to be combined to sulfonic acid groups in PEMs by electrostatic forces. For the cell containing cupric ions (Cu2+) equivalent to 1000 pmm of supfonic acid groups in PEM, a decrease in deteriorating rate of cell voltage was observed to be 83 mV/kh during 500-hour generation, in comparison with the cell without metal-ion comtamination showing 154 mV/kh. On the other hand, an increase in deteriorating rates were observed for the cells containing 10 % Cu2+ or 1000 ppm aluminum ions (Al3+). Al3+ adulteration in PEFC set off increases in activation overpotential and fluoride ion release rate (FRR) with proceeding genaration test. An increase in activation overpotentials was supressed in 1000 ppm Cu2+-adulterated cell and the reverse was observed in 10 % Cu2+-adulterated one, though Cu2+ adulterations suppressed growths of platinum catalyst particles in size and FRR regardless of Cu2+ concentration. Restriction effect of 1000 ppm Cu2+-adulteration into PEM on PEFC voltage deterioration has found to be the unprecedented knoledge with respect to PEFC degradation phenomena. Mechanisms of those influences were also discussed.

Amitani, Chieko; Ishikawa, Masahiko; Mori, Kouya; Tanaka, Kenji; Hori, Michio

270

Anaerobic degradation of inedible crop residues produced in a Controlled Ecological Life Support System  

NASA Technical Reports Server (NTRS)

An anaerobic reactor seeded with organisms from an anaerobic lagoon was used to study the degradation of inedible crop residues from potato and wheat crops grown in a closed environment. Conversion of this biomass into other products was also evaluated. Degradation of wheat volatile solids was about 25% where that of potato was about 50%. The main product of the anaerobic fermentation of both crops was acetic acid with smaller quantities of propionate and butyrate produced. Nitrate, known to be high in concentration in inedible potato and wheat biomass grown hydroponically, was converted to ammonia in the anaerobic reactor. Both volatile fatty acid and ammonia production may have implications in a crop production system.

Schwingel, W. R.; Sager, J. C.

1996-01-01

271

Multiple Sclerosis Autoantigen Myelin Basic Protein Escapes Control by Ubiquitination during Proteasomal Degradation*  

PubMed Central

The vast majority of cellular proteins are degraded by the 26S proteasome after their ubiquitination. Here, we report that the major component of the myelin multilayered membrane sheath, myelin basic protein (MBP), is hydrolyzed by the 26S proteasome in a ubiquitin-independent manner both in vitro and in mammalian cells. As a proteasomal substrate, MBP reveals a distinct and physiologically relevant concentration range for ubiquitin-independent proteolysis. Enzymatic deimination prevents hydrolysis of MBP by the proteasome, suggesting that an abnormally basic charge contributes to its susceptibility toward proteasome-mediated degradation. To our knowledge, our data reveal the first case of a pathophysiologically important autoantigen as a ubiquitin-independent substrate of the 26S proteasome. PMID:24739384

Belogurov, Alexey; Kudriaeva, Anna; Kuzina, Ekaterina; Smirnov, Ivan; Bobik, Tatyana; Ponomarenko, Natalia; Kravtsova-Ivantsiv, Yelena; Ciechanover, Aaron; Gabibov, Alexander

2014-01-01

272

Issues related to regulatory control of naturally occurring radioactive materials  

SciTech Connect

Nearly 80% of human radiation exposure is from naturally occurring radioactive materials (NORM). While exposure from man-made sources of radiation has been well regulated, no consistent regulatory controls exist for NORM. Because elevated radiation levels have resulted from NORM enhancement activities such as occur in the petroleum, fertilizer, mining, and processing industries, some form of regulatory control is in order. In the US, regulation of NORM by federal agencies such as the Nuclear Regulatory Commission or the Environmental Protection Agency is not anticipated in the near future because there are no authorizing federal statutes. Important issues for addressing the control of NORM include source characterization and generation, radiation protection concerns, waste management and disposition, and the regulatory framework.

Chen, S.Y.

1997-04-01

273

Deterministic control of ferroelastic switching in multiferroic materials.  

PubMed

Multiferroic materials showing coupled electric, magnetic and elastic orderings provide a platform to explore complexity and new paradigms for memory and logic devices. Until now, the deterministic control of non-ferroelectric order parameters in multiferroics has been elusive. Here, we demonstrate deterministic ferroelastic switching in rhombohedral BiFeO(3) by domain nucleation with a scanning probe. We are able to select among final states that have the same electrostatic energy, but differ dramatically in elastic or magnetic order, by applying voltage to the probe while it is in lateral motion. We also demonstrate the controlled creation of a ferrotoroidal order parameter. The ability to control local elastic, magnetic and torroidal order parameters with an electric field will make it possible to probe local strain and magnetic ordering, and engineer various magnetoelectric, domain-wall-based and strain-coupled devices. PMID:19893529

Balke, N; Choudhury, S; Jesse, S; Huijben, M; Chu, Y H; Baddorf, A P; Chen, L Q; Ramesh, R; Kalinin, S V

2009-12-01

274

Functionalized mesoporous silica materials for controlled drug delivery.  

PubMed

In the past decade, non-invasive and biocompatible mesoporous silica materials as efficient drug delivery systems have attracted special attention. Great progress in structure control and functionalization (magnetism and luminescence) design has been achieved for biotechnological and biomedical applications. This review highlights the most recent research progress on silica-based controlled drug delivery systems, including: (i) pure mesoporous silica sustained-release systems, (ii) magnetism and/or luminescence functionalized mesoporous silica systems which integrate targeting and tracking abilities of drug molecules, and (iii) stimuli-responsive controlled release systems which are able to respond to environmental changes, such as pH, redox potential, temperature, photoirradiation, and biomolecules. Although encouraging and potential developments have been achieved, design and mass production of novel multifunctional carriers, some practical biological application, such as biodistribution, the acute and chronic toxicities, long-term stability, circulation properties and targeting efficacy in vivo are still challenging. PMID:22441299

Yang, Piaoping; Gai, Shili; Lin, Jun

2012-05-01

275

46 CFR 128.240 - Hydraulic or pneumatic power and control-materials and pressure design.  

Code of Federal Regulations, 2011 CFR

...pneumatic power and control-materials and pressure design. 128.240 Section 128...EQUIPMENT AND SYSTEMS Materials and Pressure Design § 128.240 Hydraulic or pneumatic power and control—materials and pressure design. (a) Each standard...

2011-10-01

276

A Novel Photocatalytic Material for Removing Microcystin-LR under Visible Light Irradiation: Degradation Characteristics and Mechanisms  

PubMed Central

Background and Purpose Microcystin-LR (MC-LR), a common toxic species in contaminated aquatic systems, persists for long periods because of its cyclic structure. Ag3PO4 is an environment-friendly photocatalyst with relatively good degradation capacity for hazardous organic pollutants. This study aimed to investigate the degradation capacity of Ag3PO4 for MC-LR under visible light. Methods An Ag3PO4 photocatalyst was synthesized by the ion-exchange method and characterized by X-ray diffraction, field-emission scanning electron microscope, and UV-Vis spectrophotometer. MC-LR was quantified in each sample through high-performance liquid chromatograph. The degradation efficiency of MC-LR was affected by initial pH, initial Ag3PO4 concentration, initial MC-LR concentration, and recycle experiments. The degradation intermediates of MC-LR were examined by liquid chromatography-mass spectrometry (LC/MS). Results The degradation process can be well fitted with the pseudo-first-order kinetic model. The maximum MC-LR degradation rate of 99.98% can be obtained within 5 h under the following optimum conditions: pH of 5.01, Ag3PO4 concentration of 26.67 g/L, and MC-LR concentration of 9.06 mg/L. Nine intermediates were detected and analyzed by LC/MS. Three main degradation pathways were proposed based on the molecular weight of the intermediates and the reaction mechanism: (1) hydroxylation on the aromatic ring of Adda, (2) hydroxylation on the diene bonds of Adda, and (3) internal interactions on the cyclic structure of MC-LR. Conclusion Ag3PO4 is a highly efficient catalyst for MC-LR degradation in aqueous solutions. PMID:24755986

Sui, Xin; Wang, Xiangrong; Huang, Honghui; Peng, Guotao; Wang, Shoubing; Fan, Zhengqiu

2014-01-01

277

Bacterial populations and environmental factors controlling cellulose degradation in an acidic Sphagnum peat.  

PubMed

Northern peatlands represent a major global carbon store harbouring approximately one-third of the global reserves of soil organic carbon. A large proportion of these peatlands consists of acidic Sphagnum-dominated ombrotrophic bogs, which are characterized by extremely low rates of plant debris decomposition. The degradation of cellulose, the major component of Sphagnum-derived litter, was monitored in long-term incubation experiments with acidic (pH 4.0) peat extracts. This process was almost undetectable at 10°C and occurred at low rates at 20°C, while it was significantly accelerated at both temperature regimes by the addition of available nitrogen. Cellulose breakdown was only partially inhibited in the presence of cycloheximide, suggesting that bacteria participated in this process. We aimed to identify these bacteria by a combination of molecular and cultivation approaches and to determine the factors that limit their activity in situ. The indigenous bacterial community in peat was dominated by Alphaproteobacteria and Acidobacteria. The addition of cellulose induced a clear shift in the community structure towards an increase in the relative abundance of the Bacteroidetes. Increasing temperature and nitrogen availability resulted in a selective development of bacteria phylogenetically related to Cytophaga hutchinsonii (94-95% 16S rRNA gene sequence similarity), which densely colonized microfibrils of cellulose. Among isolates obtained from this community only some subdivision 1 Acidobacteria were capable of degrading cellulose, albeit at a very slow rate. These Acidobacteria represent indigenous cellulolytic members of the microbial community in acidic peat and are easily out-competed by Cytophaga-like bacteria under conditions of increased nitrogen availability. Members of the phylum Firmicutes, known to be key players in cellulose degradation in neutral habitats, were not detected in the cellulolytic community enriched at low pH. PMID:21564458

Pankratov, Timofey A; Ivanova, Anastasia O; Dedysh, Svetlana N; Liesack, Werner

2011-07-01

278

Controlled doping of semiconducting titania nanosheets for tailored spinelectronic materials.  

PubMed

Ti1-x-yFexCoyO2 nanosheets are synthesized in which the (Fe/Co) content is systematically controlled in the range of 0 ? x ? 0.4 and 0 ? y ? 0.2. A key feature of this new preparation is the use of (Li/Fe)-, (Fe/Co)- and (Li/Co)-co-substituted layered titanates as starting materials. In exfoliated nanosheets, the composition can be intentionally modified by controlled Fe/Co substitution into Ti sites during the solid-state synthesis of the starting layered compounds. The composition of the host layers is maintained in the subsequent exfoliation process, which is very helpful in the rational design of nanosheets through the use of controlled doping. Through this controlled doping, we achieve exquisite control of the electronic properties of Ti1-?O2 nanosheets, including the position of impurity bands, the Fermi energy and ferromagnetic properties. From photoelectron spectroscopy and first-principles studies, we have observed that the use of Fe/Co co-doping with higher Fe and Co oxidation states is necessary to bring the highest occupied Fe/Co impurity states to the Fermi level. This band engineering transforms the Ti1-x-yFexCoyO2 nanosheet into a room-temperature half-metallic ferromagnet, thus accomplishing the main requirements of future spinelectronics. PMID:25351176

Osada, Minoru; Yoguchi, Satoshi; Itose, Masayuki; Li, Bao-Wen; Ebina, Yasuo; Fukuda, Katsutoshi; Kotani, Yoshinori; Ono, Kanta; Ueda, Shigenori; Sasaki, Takayoshi

2014-11-01

279

Degradation of FEP thermal control materials returned from the Hubble Space Telescope  

Microsoft Academic Search

After an initial 3.6 years of space flight, the Hubble Space Telescope was serviced through a joint effort with the NASA and the European Space Agency. Multi-layer insulation (MLI) was retrieved from the electronics boxes of the two magnetic sensing systems (MSS), also called the magnetometers, and from the returned solar array (SA-I) drive arm assembly. The top layer of

T. M. Zuby; K. K. Degroh; D. C. Smith

1995-01-01

280

Methodology for materials control and accounting information systems  

SciTech Connect

Modern approaches to nuclear materials safeguards have significantly increased the data processing needs of safeguards information systems. Implementing these approaches will require developing efficient, cost-effective designs. Guided by database design research, we are developing a design methodology for distributed materials control and accounting (MC and A) information systems. The methodology considers four design parameters: network topology, allocation of data to nodes, high-level global processing strategy, and local file structures to optimize system performance. Characteristics of system performance that are optimized are response time for an operation, timeliness of data, validity of data, and reliability. The ultimate goal of the research is to develop a comprehensive computerized design tool specifically tailored to the design of MC and A systems.

Helman, P.; Strittmatter, R.B.

1987-01-01

281

Selection of optimal composition-control parameters for friable materials  

SciTech Connect

A method for composition analysis of coal and minerals is proposed which uses scattered gamma radiation and does away with preliminary sample preparation to ensure homogeneous particle density, surface area, and size. Reduction of the error induced by material heterogeneity has previously been achieved by rotation of the control object during analysis. A further refinement is proposed which addresses the necessity that the contribution of the radiation scattered from each individual surface to the total intensity be the same. This is achieved by providing a constant linear rate of travel for the irradiated spot through back-and-forth motion of the sensor. An analytical expression is given for the laws of motion for the sensor and test tube which provides for uniform irradiated area movement along a path analogous to the Archimedes spiral. The relationships obtained permit optimization of measurement parameters in analyzing friable materials which are not uniform in grain size.

Pak, Yu.N.; Vdovkin, A.V.

1988-05-01

282

[Heavy metal]-Chlorophylls Formed in Vivo During Heavy Metal Stress and Degradation Products Formed During Digestion, Extraction and Storage of Plant Material  

Microsoft Academic Search

This chapter discusses the occurrence, properties and relevance of chlorophyll (Chl) degradation products that are formed\\u000a either in vivo in heavy metal-stressed plants or by digestion of algae in marine invertebrates, or that are formed during extraction or processing of dead plant material. The in vivo substitution of the central Mg2+ ion of chlorophyll by heavy metals constitutes an important

Hendrik Küpper; Frithjof C. Küpper; Martin Spiller

283

Development of Tailorable Electrically Conductive Thermal Control Material Systems  

NASA Technical Reports Server (NTRS)

The optical characteristics of surfaces on spacecraft are fundamental parameters in controlling its temperature. Passive thermal control coatings with designed solar absorptance and infrared emittance properties have been developed and have been in use for some time. In this total space environment, the coating must be stable and maintain its desired optical properties as well as mechanical properties for the course of the mission lifetime. The mission lifetimes are increasing and in our quest to save weight, newer substrates are being integrated which limit electrical grounding schemes. All of this has added to already existing concerns about spacecraft charging and related spacecraft failures or operational failures. The concern is even greater for thermal control surfaces that are very large. One way of alleviating such concerns is to design new thermal control material systems (TCMS) that can help to mitigate charging via providing charge leakage paths. The objective of this program was to develop two types of passive electrically conductive TCMS. The first was a highly absorbing/emitting black surface and the second was a low (alpha(sub s)/epsilon(sub N)) type white surface. The surface resistance goals for the black absorber was 10(exp 4) to 10(exp 9) Omega/square, and for the white surfaces it was 10(exp 6) to 10(exp 10) Omega/square. Several material system concepts were suggested and evaluated for space environment stability and electrical performance characterization. Our efforts in designing and evaluating these material systems have resulted in several developments. New concepts, pigments and binders have been developed to provide new engineering quality TCMS. Some of these have already found application on space hardware, some are waiting to be recognized by thermal designers, and some require further detailed studies to become state-of-the-art for future space hardware and space structures. Our studies on baseline state-of-the-art materials and conductive concepts have resulted in several important findings that are of interest to all thermal designers and systems integrators.

Deshpande, M. S.; Harada, Y.

1997-01-01

284

Methods of measurement for semiconductor materials, process control, and devices  

NASA Technical Reports Server (NTRS)

The development of methods of measurement for semiconductor materials, process control, and devices is discussed. The following subjects are also presented: (1) demonstration of the high sensitivity of the infrared response technique by the identification of gold in a germanium diode, (2) verification that transient thermal response is significantly more sensitive to the presence of voids in die attachment than steady-state thermal resistance, and (3) development of equipment for determining susceptibility of transistors to hot spot formation by the current-gain technique.

Bullis, W. M. (editor)

1971-01-01

285

Methods of measurement for semiconductor materials, process control, and devices  

NASA Technical Reports Server (NTRS)

Activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices are described. Topics investigated include: measurements of transistor delay time; application of the infrared response technique to the study of radiation-damaged, lithium-drifted silicon detectors; and identification of a condition that minimizes wire flexure and reduces the failure rate of wire bonds in transistors and integrated circuits under slow thermal cycling conditions. Supplementary data concerning staff, standards committee activities, technical services, and publications are included as appendixes.

Bullis, W. M. (editor)

1972-01-01

286

In vitro degradation and cytotoxicity response of Mg-4% Zn-0.5% Zr (ZK40) alloy as a potential biodegradable material.  

PubMed

Mg-4 wt.% Zn-0.5 wt.% Zr (ZK40) alloy was studied as a candidate material for biodegradable metallic implants in terms of its biocorrosion resistance, mechanical properties and cytocompatibility. The corrosion characteristics of ZK40 alloy were assessed by potentiodynamic polarization and immersion testing in DMEM+10% FBS solution. Analysis of the degradation characteristics by potentiodynamic polarization measurements shows the corrosion rates of ZK40 alloy in as-cast and solution treatment (T4) condition were slightly higher than those of pure Mg or as-drawn AZ31. Determination of the corrosion rate by the weight loss technique reveals that the as-cast ZK40 resulted in slower degradation than other alloy specimens after 7 days of immersion but exhibited accelerated degradation after 14 and 21 days, respectively. T4-treated ZK40 exhibited stable degradation rates compared to as-cast ZK40 and close to those of pure Mg and AZ31 during immersion testing for 14 and 21 days. In order to examine the in vitro cytocompatibility of ZK40 alloy, live/dead cell viability assay and indirect MTT assay were performed using a murine osteoblast-like cell line (MC3T3). After 3 days of direct culture of MC3T3 on ZK40 alloys the live/dead assay indicated favorable cell viability and attachment. The degradation product of ZK40 also showed minimal cytotoxicity when assessed in indirect MTT assay. The mechanical properties of the as-cast and T4-treated ZK40 alloy were superior to those of pure Mg and comparable to as-drawn AZ31. Solution treatment did not significantly enhance the cytocompatibility and mechanical properties of ZK40 alloy. Overall, the ZK40 alloy exhibited favorable cytocompatibility, biocorrosion, and mechanical properties rendering it a potential candidate for degradable implant applications. PMID:23851175

Hong, Daeho; Saha, Partha; Chou, Da-Tren; Lee, Boeun; Collins, Boyce E; Tan, Zongqing; Dong, Zhongyun; Kumta, Prashant N

2013-11-01

287

Methods of Measurement for Semiconductor Materials, Process Control, and Devices  

NASA Technical Reports Server (NTRS)

The development of methods of measurement for semiconductor materials, process control, and devices is reported. Significant accomplishments include: (1) Completion of an initial identification of the more important problems in process control for integrated circuit fabrication and assembly; (2) preparations for making silicon bulk resistivity wafer standards available to the industry; and (3) establishment of the relationship between carrier mobility and impurity density in silicon. Work is continuing on measurement of resistivity of semiconductor crystals; characterization of generation-recombination-trapping centers, including gold, in silicon; evaluation of wire bonds and die attachment; study of scanning electron microscopy for wafer inspection and test; measurement of thermal properties of semiconductor devices; determination of S-parameters and delay time in junction devices; and characterization of noise and conversion loss of microwave detector diodes.

Bullis, W. M. (ed)

1973-01-01

288

Effects of Contamination, UV Radiation, and Atomic Oxygen on ISS Thermal Control Materials  

NASA Technical Reports Server (NTRS)

Thermal control surfaces on the International Space Station (ISS) have been tailored for optimum optical properties. The space environment, particularly contamination, ultraviolet (UV) radiation, and atomic oxygen (AO) may have a detrimental effect on these optical properties. These effects must be quantified for modeling and planning. Also of interest was the effect of porosity on the reaction to simulated space environment. Five materials were chosen for this study based on their use on ISS. The thermal control materials were Z-93 white coating, silverized Teflon, chromic acid anodized aluminum, sulfuric acid anodized aluminum, and 7075-T6 aluminum. Some of the samples were exposed to RTV 560 silicone; others were exposed to Tefzel offgassing products. Two samples of Z-93 were not exposed to contamination as clean "controls". VUV radiation was used to photo-fix the contaminant to the material surface, then the samples were exposed to AO. All samples were exposed to 1000 equivalent sun-hours (ESH) of vacuum ultraviolet radiation (VUV) at the AZ Technology facility and a minimum of 1.5 x 10(exp 20) atoms/sq cm of AO at Marshall Space Flight Center. Half of the samples were exposed to an additional 2000 ESH of VUV at Huntington Beach prior to sent to AZ Technology. Darkening of the Z-93 white coating was noted after VUV exposure. AO exposure did bleach the Z-93 but not back to its original brightness. Solar absorptance curves show the degradation due to contamination and VUV and the recovery with AO exposure. More bleaching was noted on the Tefzel-contaminated samples than with the RTV-contaminated samples.

Visentine, Jim; Finckenor, Miria; Zwiener, Jim; Munafo, Paul (Technical Monitor)

2001-01-01

289

Materials degradation in low earth orbit (LEO); Proceedings of the Symposium, 119th Annual Meeting of the Minerals, Metals, and Materials Society, Anaheim, CA, Feb. 17-22, 1990  

NASA Technical Reports Server (NTRS)

The current understanding of the effect of space environment on materials and the development of protective coatings is examined in reviews and reports. Consideration is given to hyperthermal atomic oxygen reactions, the effect of atomic oxygen on altered and coated Kapton surfaces for spacecraft applications in LEO, silicon dioxide space coatings studied ellipsometrically, atomic oxygen effects on spacecraft materials, atomic oxygen beam source for erosion simulation, and atomic oxygen effects on refractory materials. Particular attention is given to ellipsometric analysis of materials degradation in space, studies of the interaction of 8 km/s oxygen atoms with selected materials, characterization and calibration of the EOIM-III flight mass spectrometer in a high velocity oxygen atom beam, the reaction efficiency of thermal energy oxygen atoms with polymeric materials, and effects of simulated space environments on the properties of selected materials.

Srinivasan, V. (editor); Banks, Bruce A. (editor)

1990-01-01

290

Controlling the band gap energy of cluster-assembled materials.  

PubMed

Cluster-assembled materials combine the nanoscale size and composition-dependent properties of clusters, which have highly tunable magnetic and electronic properties useful for a great variety of potential technologies. To understand the emergent properties as clusters are assembled into hierarchical materials, we have synthesized 23 cluster-assembled materials composed of As7(3-)-based motifs and different countercations and measured their band gap energies. We found that the band gap energy varies from 1.09 to 2.21 eV. In addition, we have carried out first principles electronic structure studies to identify the physical mechanisms that enable control of the band gap edges of the cluster assemblies. The choice of counterion has a profound effect on the band gap energy in ionic cluster assemblies. The top of the valence band is localized on the arsenic cluster, while the conduction band edge is located on the alkali metal counterions. Changing the counterion changes the position of the conduction band edge, enabling control of the band gap energy. We can also vary the architecture of the ionic solid by incorporating cryptates as counterions, which provide charge but are separated from the clusters by bulky ligands. Higher dimensionality typically decreases the band gap energy through band broadening; however band gap energies increased upon moving from zero-dimensional (0D) to two-dimensional (2D) assemblies. This is because internal electric fields generated by the counterion preferentially stabilize the adjacent lone pair orbitals that mark the top of the valence band. Thus, the choice of the counterion can control the position of the conduction band edge of ionic cluster assemblies. In addition, the dimensionality of the solid via internal electric fields can control the valence band edge. Through covalently linking arsenic clusters into composite building blocks, we have also been able to tune the band gap energy. We used a theoretical description based on cluster orbital theory to provide microscopic understanding of the electronic character of the composite building blocks and the observed variations in the band gap energy. Also, we have shown how dimeric linkers can be used to control the band gap energy. Lastly, we also investigated the effects of charge transfer complexes of M(CO)3 on the band gap energy. PMID:23734558

Mandal, Sukhendu; Reber, Arthur C; Qian, Meichun; Weiss, Paul S; Khanna, Shiv N; Sen, Ayusman

2013-11-19

291

Hands-free mobile phone speech while driving degrades coordination and control  

Microsoft Academic Search

Using a closed-circuit driving track environment, we investigated the influence of using a hands-free mobile (or cell) phone on various biomechanical and perceptual factors that underlie the control of driving. Results showed that in three tasks representative of everyday driving conditions, the perceptual control of action was compromised when compared to a control condition where no mobile phone conversation was

Paul J. Treffner; Rod Barrett

2004-01-01

292

Magnetically Controlled Shape Memory Behaviour—Materials and Applications  

NASA Astrophysics Data System (ADS)

For most metals a microscopic change in shape occurs above the elastic limit by the irreversible creation and movement of dislocations. However a large number of metallic systems undergo structural, martensitic, phase transformations which are diffusionless, displacive first order transitions from a high-temperature phase to one of lower symmetry below a certain temperature TM. These transitions which have been studied for more than a century are of vital importance because of their key role in producing shape memory phenomena enabling the system to reverse large deformations in the martensitic phase by heating into the austenite phase. In addition to a change in shape (displacement) the effect can also produce a force or a combination of both. Materials having this unique property are increasing being used in medical applications—scoliosis correction, arterial clips, stents, orthodontic wire, orthopaedic implants etc. The structural phase transition essential for shape memory behaviour is usually activated by a change in temperature or applied stress. However for many applications such as for actuators the transformation is not sufficiently rapid. Poor energy conversion also limits the applicability of many shape memory alloys. In medicine a change of temperature or pressure is often inappropriate and new ferromagnetic materials are being considered in which the phenomena can be controlled by an applied magnetic field at constant temperature. In order to achieve this, it is important to optimise three fundamental parameters. These are the saturation magnetisation ?s, the Curie temperature Tc and the martensitic temperature TM. Here, ?s is important because the magnetic pressure driving the twin boundary motion is 2?sH. Furthermore the material must be in the martensitic state at the operating temperature which should be at or above room temperature. This may be achieved by alloying or controlling the stoichiometry. Recently new intermetallic compounds based on the ferromagnetic prototype Ni2MnGa have been discovered which offer the possibility of controlling the structural phase transition by a magnetic field, hence opening up new possible applications particularly in the field of medicine. The properties of these new materials will be presented and their suitability for applications discussed.

Gandy, A. P.; Sheikh, A.; Neumann, K.; Neumann, K.-U.; Pooley, D.; Ziebeck, K. R. A.

2008-06-01

293

Exposure of Polymer Film Thermal Control Materials on the Materials International Space Station Experiment (MISSE)  

NASA Technical Reports Server (NTRS)

Seventy-nine samples of polymer film thermal control (PFTC) materials have been provided by the National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) for exposure to the low Earth orbit environment on the exterior of the International Space Station (ISS) as part of the Materials International Space Station Experiment (MISSE). MISSE is a materials flight experiment sponsored by the Air Force Research Lab/Materials Lab and NASA. This paper will describe background, objectives, and configurations for the GRC PFTC samples for MISSE. These samples include polyimides, fluorinated polyimides, and Teflon fluorinated ethylene propylene (FEP) with and without second-surface metallizing layers and/or surface coatings. Also included are polyphenylene benzobisoxazole (PBO) and a polyarylene ether benzimidazole (TOR-LM). On August 16, 2001, astronauts installed passive experiment carriers (PECs) on the exterior of the ISS in which were located twenty-eight of the GRC PFTC samples for 1-year space exposure. MISSE PECs for 3-year exposure, which will contain fifty-one GRC PFTC samples, will be installed on the ISS at a later date. Once returned from the ISS, MISSE GRC PFTC samples will be examined for changes in optical and mechanical properties and atomic oxygen (AO) erosion. Additional sapphire witness samples located on the AO exposed trays will be examined for deposition of contaminants.

Dever, Joyce; Miller, Sharon; Messer, Russell; Sechkar, Edward; Tollis, Greg

2002-01-01

294

Signal Transducer and Activator of Transcription 3 (STAT3) Degradation by Proteasome Controls a Developmental Switch in Neurotrophin Dependence*  

PubMed Central

Neonatal brains develop through a program that eliminates about half of the neurons. During this period, neurons depend on neurotrophins for their survival. Recently, we reported that, at the conclusion of the naturally occurring death period, neurons become neurotrophin-independent and, further, that this developmental switch is achieved by the emergence of a second survival pathway mediated by signal transducer and activator of transcription 3 (STAT3). Here I show that calcineurin plays a key role in controlling the developmental switch in mouse hippocampal neurons. Calcineurin promotes the degradation of STAT3 via the ubiquitin-proteasome pathway. Inhibition of calcineurin acutely increases total levels of STAT3 as well as its activated forms, resulting in decreased levels of the tumor suppressor p53 and its proapoptotic target, Bax. In vivo and in vitro, calcineurin regulates levels of STAT3 and neurotrophin dependence. TMF/ARA 160 (TATA element modulatory factor/androgen receptor co-activator 160), the key mediator of STAT3 ubiquitination, is required for calcineurin-dependent STAT3 degradation. Thus, these results show that the ubiquitin-proteasome pathway controls the critical developmental switch of neurotrophin dependence in the newborn hippocampus. PMID:23733189

Murase, Sachiko

2013-01-01

295

A testbed for advanced materials control and accounting concepts  

SciTech Connect

Advanced concepts in materials control and accounting include distributed databases in a distributed process environment and on-line instrumentation. To test various ideas in this area, we developed a testbed consisting of three personal computers /PCs/ with several input devices and suitable software. The principal design aspects being tested include database structure, communication between various network nodes, database update on the host, speed of transaction processing, data input from on-line instrumentation, and a user-friendly interface with the operator. An IBM PC/XT at the local level is used to collect data using a barcode reader and balance in a mockup glove box. These represent typical examples of simple on-line instrumentation in nuclear material facilities. Manual input to the PC/XT is through a keyboard, a mouse, and a voice microphone. This PC/XT communicates with a host PC/AT that serves to post transactions for a process area or wing of a facility. A second PC/AT represents the central computer that collects data from several distributed nodes and maintains the central database for analysis and report generation. Custom software is called PC/DYMAC, a materials accounting package developed by Robert Bearse in cooperation with Argonne National Laboratory-West under the direction and funding of the Los Alamos Safeguards research and development program. It was developed using dBaseIII PLUS but was compiled with FoxBASE/plus/ under the Santa Cruz Operations XENIX operating system. 4 refs. 1 fig.

Tisinger, R.M.

1988-01-01

296

Degradation of IF1 controls energy metabolism during osteogenic differentiation of stem cells  

PubMed Central

Differentiation of human mesenchymal stem cells (hMSCs) requires the rewiring of energy metabolism. Herein, we demonstrate that the ATPase inhibitory factor 1 (IF1) is expressed in hMSCs and in prostate and colon stem cells but is not expressed in the differentiated cells. IF1 inhibits oxidative phosphorylation and regulates the activity of aerobic glycolysis in hMSCs. Silencing of IF1 in hMSCs mimics the metabolic changes observed in osteocytes and accelerates cellular differentiation. Activation of IF1 degradation acts as the switch that regulates energy metabolism during differentiation. We conclude that IF1 is a stemness marker important for maintaining the quiescence state. PMID:23722655

Sanchez-Arago, Maria; Garcia-Bermudez, Javier; Martinez-Reyes, Inmaculada; Santacatterina, Fulvio; Cuezva, Jose M

2013-01-01

297

Multiphasic control of hepatic protein degradation by regulatory amino acids. General features and hormonal modulation.  

PubMed

Previous studies with livers from fed rats perfused in the single-pass mode have shown that regulatory amino acids (Leu, Tyr, Gln, Pro, Met, His, and Trp) as a group as well as leucine alone inhibit deprivation-induced protein degradation optimally at 0.5 and 4 times (X) normal plasma amino acid concentrations. However, they lose inhibitory effectiveness almost completely within a narrow zone centered at normal (1 X) levels (Pösö, A. R., Wert, J. J., Jr., and Mortimore, G.E. (1982) J. Biol. Chem. 257, 12114-12120; Pösö, A. R., and Mortimore, G. E. (1984) Proc. Natl. Acad. Sci. U. S. A. 81, 4270-4274). We now report similar effects for tyrosine and glutamine and suggest that this multiphasic dose response is a general feature of the regulatory group. Insulin (2.4 micrograms h-1) selectively modulated the response by abolishing the zonal loss, whereas glucagon (10 micrograms h-1) blocked the initial inhibition (0.5 X); proteolytic suppression was restored at 4 X normal plasma levels. Although the zonal loss of inhibition at 1 X was associated with a near maximal increase in the volume density of macroautophagy, the vacuoles differed from those induced by stringent amino acid deprivation in containing 4.5-fold more smooth than rough endoplasmic reticulum and thus represented a separate population. Surprisingly, the leucine analog, L-alpha-hydroxyisocaproate, elicited multiphasic responses identical to those of L-leucine, including inhibition at 0.1 mM (equivalent to 0.5 X Leu). Inasmuch as alpha-ketoisocaproate is not effective at this concentration, the initial suppression of protein degradation could be mediated from a site that recognizes structural features common to leucine and its hydroxyl analog. PMID:3316218

Mortimore, G E; Pösö, A R; Kadowaki, M; Wert, J J

1987-12-01

298

Fabrication of enzyme-degradable and size-controlled protein nanowires using single particle nano-fabrication technique  

PubMed Central

Protein nanowires exhibiting specific biological activities hold promise for interacting with living cells and controlling and predicting biological responses such as apoptosis, endocytosis and cell adhesion. Here we report the result of the interaction of a single high-energy charged particle with protein molecules, giving size-controlled protein nanowires with an ultra-high aspect ratio of over 1,000. Degradation of the human serum albumin nanowires was examined using trypsin. The biotinylated human serum albumin nanowires bound avidin, demonstrating the high affinity of the nanowires. Human serum albumin–avidin hybrid nanowires were also fabricated from a solid state mixture and exhibited good mechanical strength in phosphate-buffered saline. The biotinylated human serum albumin nanowires can be transformed into nanowires exhibiting a biological function such as avidin–biotinyl interactions and peroxidase activity. The present technique is a versatile platform for functionalizing the surface of any protein molecule with an extremely large surface area. PMID:24770668

Omichi, Masaaki; Asano, Atsushi; Tsukuda, Satoshi; Takano, Katsuyoshi; Sugimoto, Masaki; Saeki, Akinori; Sakamaki, Daisuke; Onoda, Akira; Hayashi, Takashi; Seki, Shu

2014-01-01

299

Fabrication of enzyme-degradable and size-controlled protein nanowires using single particle nano-fabrication technique  

NASA Astrophysics Data System (ADS)

Protein nanowires exhibiting specific biological activities hold promise for interacting with living cells and controlling and predicting biological responses such as apoptosis, endocytosis and cell adhesion. Here we report the result of the interaction of a single high-energy charged particle with protein molecules, giving size-controlled protein nanowires with an ultra-high aspect ratio of over 1,000. Degradation of the human serum albumin nanowires was examined using trypsin. The biotinylated human serum albumin nanowires bound avidin, demonstrating the high affinity of the nanowires. Human serum albumin-avidin hybrid nanowires were also fabricated from a solid state mixture and exhibited good mechanical strength in phosphate-buffered saline. The biotinylated human serum albumin nanowires can be transformed into nanowires exhibiting a biological function such as avidin-biotinyl interactions and peroxidase activity. The present technique is a versatile platform for functionalizing the surface of any protein molecule with an extremely large surface area.

Omichi, Masaaki; Asano, Atsushi; Tsukuda, Satoshi; Takano, Katsuyoshi; Sugimoto, Masaki; Saeki, Akinori; Sakamaki, Daisuke; Onoda, Akira; Hayashi, Takashi; Seki, Shu

2014-04-01

300

Shape control of composite material plates using piezoelectric actuators  

NASA Astrophysics Data System (ADS)

This paper concerns the shape control of composite material plates using piezoelectric actuators. A finite element formulation is developed for modeling a laminated composite plate that has piezoelectric actuators and sensors. To improve the accuracy of the prediction of the plate deformation, a simple higher-order deformation theory is used. The electrical potential is treated as a generalized coordinate, allowing it to vary over the element. For the shape control, an optimization algorithm, based on finite element techniques, is developed to determine optimal actuator voltages to minimize the surface error between the desired shape and actual deformed shape. The error function for a plate element is determined by calculating the mean square of the surface error over the surface, instead of determining it only at the node points of the element. Based on these techniques, Matlab codes were developed. Analyses were performed to determine optimum actuator voltages. The analytical results demonstrate the feasibility of using piezoelectric actuators for the active shape control of spacecraft reflectors.

Agrawal, Brij N.; Elshafei, M. A.

1997-11-01

301

Extremum seeking control based integration of MPPT and degradation detection for photovoltaic arrays  

Microsoft Academic Search

Regarding the reduction of the cost of energy (COE) for photovoltaic (PV) systems, two important issues are maximizing the efficiency of power generation and fault diagnosis. This study presents an integrated framework that achieves both maximum power point tracking (MPPT) control and diagnosis of change in internal resistance simultaneously. An extremum seeking control (ESC) strategy is developed to maximize the

Peng Lei; Yaoyu Li; Quan Chen; John E. Seem

2010-01-01

302

Control of glutamate homeostasis in Bacillus subtilis: a complex interplay between ammonium assimilation, glutamate biosynthesis and degradation.  

PubMed

Glutamate, the major amino group donor in anabolism, is synthesized by the combined action of the glutamine synthetase (GS) and the glutamate synthase (GOGAT) in Bacillus subtilis. The glutamate dehydrogenase (GDH) exclusively degrades glutamate. GS and GDH are both trigger enzymes, active in nitrogen metabolism and in controlling gene expression. Feedback-inhibited GS (FBI-GS) controls DNA-binding activities of two transcription factors, the repressor GlnR and TnrA, the global regulator of nitrogen metabolism. FBI-GS binds to and activates GlnR. This protein complex inhibits GS formation and thus glutamine synthesis. Moreover, FBI-GS inhibits DNA-binding activity of TnrA. Glutamate biosynthesis, the reaction linking carbon with nitrogen metabolism, is controlled by GDH. Together with glutamate GDH inhibits GltC, the transcription factor that activates expression of the GOGAT genes. Thus, GS and GDH control glutamine and glutamate synthesis, respectively, depending on the nitrogen status of the cell. B. subtilis lacking a functional GDH show a severe growth defect. Interestingly, the growth defect is suppressed by the rapid activation of an inactive GDH. Thus, maintenance of glutamate homeostasis is crucial for cellular vitality. This review covers the recent work on the complex control of glutamine and glutamate metabolism in the Gram-positive model organism B. subtilis. PMID:22625175

Gunka, Katrin; Commichau, Fabian M

2012-07-01

303

SCFCyclin F controls centrosome homeostasis and mitotic fidelity via CP110 degradation  

PubMed Central

Generally, F-box proteins are the substrate recognition subunits of SCF (Skp1-Cul1-F-box protein) ubiquitin ligase complexes, which mediate the timely proteolysis of important eukaryotic regulatory proteins1,2. Mammalian genomes encode roughly 70 F-box proteins, but only a handful have established functions3,4. The F-box protein family obtained its name from Cyclin F (also called Fbxo1), in which the F-box motif (the ~40 amino acid domain required for binding to Skp1) was first described5. Cyclin F, which is encoded by an essential gene, also contains a cyclin box domain, but in contrast to most cyclins, it does not bind or activate any cyclin-dependent kinases (CDKs)5–7. However, like other cyclins, Cyclin F oscillates during the cell cycle, with protein levels peaking in G2. Despite its essential nature and status as the founding member of the F-box protein family, Cyclin F remains an orphan protein, whose functions are unknown. Starting from an unbiased screen, we identified CP110, a protein essential for centrosome duplication, as an interactor and substrate of Cyclin F. Utilizing a mode of substrate binding distinct from other F-box protein-substrate pairs, CP110 and Cyclin F physically associate on the centrioles during the G2 phase of the cell cycle, and CP110 is ubiquitylated via the SCFCyclin F ubiquitin ligase complex, leading to its degradation. siRNA-mediated depletion of Cyclin F in G2 induces centrosomal and mitotic abnormalities, such as multipolar spindles and asymmetric, bipolar spindles with lagging chromosomes. These phenotypes were reverted by co-silencing CP110 and were recapitulated by expressing a stable mutant of CP110 that is unable to bind Cyclin F. Finally, expression of a stable CP110 mutant in cultured cells also promotes the formation of micronuclei, a hallmark of chromosome instability. We propose that SCFCyclin F–mediated degradation of CP110 is required for the fidelity of mitosis and genome integrity. PMID:20596027

D’Angiolella, Vincenzo; Donato, Valerio; Vijayakumar, Sangeetha; Saraf, Anita; Florens, Laurence; Washburn, Michael P.; Dynlacht, Brian; Pagano, Michele

2010-01-01

304

Degradation mechanisms of carbon-based electrocatalyst support materials and development of an advanced support based on electrically conducting diamond  

NASA Astrophysics Data System (ADS)

In this dissertation, the degradation mechanisms of sp 2-bonded carbon electrocatalyst supports were studied under potential and temperature conditions relevant to the polymer electrolyte membrane fuel cell (PEMFC). In addition, an alternative support was fabricated in two forms: electrically conducting diamond powder and paper to overcome current material stability issues in the PEMFC. Two structurally well-characterized sp2-bonded carbon powders, graphite (structurally well-ordered) and glassy carbon (GC, structurally disordered) were studied under potentiostatic polarization from 1.0 to 1.6 V vs. Ag/AgCl at 25, 50, and 80°C. Characterization of the surface oxidation and microstructural changes (i.e., increase in the exposed edge plane density) provided evidence for the so-called order/disorder mechanism where structurally disordered carbons corrode more severely because of oxidation and gasification of the exposed edge plane. Microstructural changes for graphite were heterogeneously distributed across the electrode surface. This is indicative of a nucleation and growth process, where disordered regions and defects serve as active sites for electrochemical corrosion, while other, more structurally ordered regions do not corrode. Preliminary results for a high-surface-area carbon black, Vulcan XC-72, are presented that show changes in the surface oxide content and also discuss the effect of polarization potential on Pt activity. The physical and electrochemical properties of two commercial boron-doped diamond thin-film electrodes were compared with microcrystalline and nanocrystalline boron-doped diamond thin film deposited in our laboratory. The electrochemical response for Fe(CN)63-/4-, Ru(NH3)6 3+/2+, IrCl62-/3-, 4-methylcatechol, and Fe3+/2+ was quite reproducible from electrode type-to-type and from film-to-film for a given type. DeltaEp, ipox, and ip red values for Fe(CN)63-/4-, Ru(NH 3)63+/2+ on all electrodes were relatively unaffected by pH. Electrically conducting diamond powder was prepared by coating insulating diamond powder (8-12 mum diam) with a thin boron-doped diamond layer using microwave-assisted chemical vapor deposition (CVD). Increases in the electrical conductivity after growth confirmed that a conductive diamond overlayer formed. The charge passed during anodic polarization at 1.6 V vs. Ag/AgCl and 25°C for 1 h was largest for GC powder (0.88 C/cm2) and smallest for conductive diamond powder (0.18 C/cm2), illustrating the dimensional stability of diamond powder compared to sp2-bonded carbon powder. Boron-doped nanocrystalline diamond (BND) was coated on Toray RTM carbon paper (TCP) via microwave-assisted CVD. Pt nanoparticles were deposited on TCP and BND using a pulsed galvanostatic method. The stability of the bare TCP and BND substrates and the composite Pt/TCP and Pt/BND electrodes were studied using potentiostatic polarization in 0.1 M HClO4. The BND electrode exhibited superior morphological and microstructural stability over TCP at 1.6 V vs. Ag/AgCl. Evidence was found for dissolution and redeposition of Pt on composite electrodes, particularly for Pt/TCP.

Fischer, Anne Elizabeth

305

Tailoring the nano-channel of ZrO 2/SBA-15 mesoporous materials for efficiently trapping and degradation volatile nitrosamines  

NASA Astrophysics Data System (ADS)

This article reports a bifunctionalized mesoporous ZrO 2/SBA-15 materials prepared through a simplified one-pot synthesis, in which the aged sample was evaporated with mother solution under the self-adjusted pH condition. The results of low-angle XRD, HRTEM, nitrogen adsorption-desorption, in-situ 1H NMR and NH 3-TPD tests confirmed the well-ordered hexagonal structure and large pore size of these composites along with the newly formed acidity and basicity. Temperature programmed surface reaction (TPSR) was employed to assess the catalytic function of ZrO 2/SBA-15 composites on the degradation of carcinogenic volatile nitrosamines such as N-nitrosopyrrolidine (NPYR). Due to the special interaction between the N-NO group of nitrosamines and the acidic site of mesoporous composite, NPYR could be efficiently trapped and then catalytic degraded at lower temperature, which enables this functional composite to be a new candidate for environment protection.

Shi, Liying; Chu, Sheng; Kong, Fei; Luo, Leilei; Wang, Ying; Zou, Zhigang

2011-12-01

306

Rationalizing the mechanism of HMDS degradation in air and effective control of the reaction byproducts  

NASA Astrophysics Data System (ADS)

The concern over molecular contamination on the surfaces of optics continues to grow. Most recently, this concern has focused on siloxane contamination resulting from hexamethyldisilazane (HMDS) which is commonly used as a wafer treatment to improve photoresist adhesion onto wafers. From this process, HMDS vapor can be found within FABs and process tools where it has been linked to issues related to lens hazing. This type of surface contamination is significantly detrimental to the imaging process and is generally corrected by extensive surface cleaning or even lens replacement. Additionally, this type of repair also requires adjustment of the optical axis, thereby contributing to an extended downtime. HMDS is known to be very sensitive to the presence of water and is therefore believed to degrade in humid airstreams. This research focuses on rationalizing the reaction mechanisms of HMDS in dry and humid airstreams and in the presence of several adsorbent surfaces. It is shown that HMDS hydrolyzes in humid air to trimethylsilanol (TMS) and ammonia (NH 3). Furthermore, it is shown that TMS can dimerize in air, or on specific types of adsorption media, to form hexamethyldisiloxane (HMDSO). Additionally, we report on the relative impact of these reaction mechanisms on the removal of both HMDS and its hydrolysis products (TMS, HMDSO and NH 3).

Seguin, Kevin; Dallas, Andrew J.; Weineck, Gerald

2008-03-01

307

Involvement of Bacillus subtilis ClpE in CtsR Degradation and Protein Quality Control  

PubMed Central

The heat-inducible CtsR regulon of Bacillus subtilis codes for three Clp proteins with chaperone or protease activity. While the importance of ClpC and ClpP has been elucidated for a wide range of cellular adaptation processes, this study deals with the physiological role of B. subtilis ClpE. Northern experiments and reporter gene analyses revealed that ClpE is essential both for efficient CtsR-dependent gene derepression and for rerepression during heat stress. ClpEP was found to destabilize the global regulator CtsR after heat shock in vivo with different kinetics than ClpCP, which is known to degrade CtsR in vitro and in vivo upon heat stress. Furthermore, ClpE was localized at heat-generated inclusion bodies by electron microscopy. The comparison of radiolabeled aggregated protein fractions of wild-type and clpE mutant cells during heat stress displayed a significant delay of protein disaggregation in the absence of ClpE. A kinetic Western blotting approach confirmed the long-term residence of ClpE in the insoluble cell fraction rather than in the cytoplasmic fraction. These observations indicate the involvement of ClpE in global protein disaggregation. As a characteristic structural element of ClpE, the N-terminal zinc finger domain was proven to be essential for basal in vitro ATPase activity. PMID:16788169

Miethke, Marcus; Hecker, Michael; Gerth, Ulf

2006-01-01

308

The Alzheimer's Amyloid-Degrading Peptidase, Neprilysin: Can We Control It?  

PubMed Central

The amyloid cascade hypothesis of Alzheimer's disease (AD) postulates that accumulation in the brain of amyloid ?-peptide (A?) is the primary trigger for neuronal loss specific to this pathology. In healthy brain, A? levels are regulated by a dynamic equilibrium between A? release from the amyloid precursor protein (APP) and its removal by perivascular drainage or by amyloid-degrading enzymes (ADEs). During the last decade, the ADE family was fast growing, and currently it embraces more than 20 members. There are solid data supporting involvement of each of them in A? clearance but a zinc metallopeptidase neprilysin (NEP) is considered as a major ADE. NEP plays an important role in brain function due to its role in terminating neuropeptide signalling and its decrease during ageing or after such pathologies as hypoxia or ischemia contribute significantly to the development of AD pathology. The recently discovered mechanism of epigenetic regulation of NEP by the APP intracellular domain (AICD) opens new avenues for its therapeutic manipulation and raises hope for developing preventive strategies in AD. However, consideration needs to be given to the diverse physiological roles of NEP. This paper critically evaluates general biochemical and physiological functions of NEP and their therapeutic relevance. PMID:22900228

Nalivaeva, N. N.; Belyaev, N. D.; Zhuravin, I. A.; Turner, A. J.

2012-01-01

309

Regulation of the cytoplasmic quality control protein degradation pathway by BAG2.  

PubMed

The cytoplasm is protected against the perils of protein misfolding by two mechanisms: molecular chaperones (which facilitate proper folding) and the ubiquitin-proteasome system, which regulates degradation of misfolded proteins. CHIP (carboxyl terminus of Hsp70-interacting protein) is an Hsp70-associated ubiquitin ligase that participates in this process by ubiquitylating misfolded proteins associated with cytoplasmic chaperones. Mechanisms that regulate the activity of CHIP are, at present, poorly understood. Using a proteomics approach, we have identified BAG2, a previously uncharacterized BAG domain-containing protein, as a common component of CHIP holocomplexes in vivo. Binding assays indicate that BAG2 associates with CHIP as part of a ternary complex with Hsc70, and BAG2 colocalizes with CHIP under both quiescent conditions and after heat shock. In vitro and in vivo ubiquitylation assays indicate that BAG2 is an efficient and specific inhibitor of CHIP-dependent ubiquitin ligase activity. This activity is due, in part, to inhibition of interactions between CHIP and its cognate ubiquitin-conjugating enzyme, UbcH5a, which may in turn be facilitated by ATP-dependent remodeling of the BAG2-Hsc70-CHIP heterocomplex. The association of BAG2 with CHIP provides a cochaperone-dependent regulatory mechanism for preventing unregulated ubiquitylation of misfolded proteins by CHIP. PMID:16169850

Dai, Qian; Qian, Shu-Bing; Li, Hui-Hua; McDonough, Holly; Borchers, Christoph; Huang, David; Takayama, Shinichi; Younger, J Michael; Ren, Hong Yu; Cyr, Douglas M; Patterson, Cam

2005-11-18

310

RNase III Controls the Degradation of corA mRNA in Escherichia coli  

PubMed Central

In Escherichia coli, the corA gene encodes a transporter that mediates the influx of Co2+, Mg2+, and Ni2+ into the cell. During the course of experiments aimed at identifying RNase III-dependent genes in E. coli, we observed that steady-state levels of corA mRNA as well as the degree of cobalt influx into the cell were dependent on cellular concentrations of RNase III. In addition, changes in corA expression levels by different cellular concentrations of RNase III were closely correlated with degrees of resistance of E. coli cells to Co2+ and Ni2+. In vitro and in vivo cleavage analyses of corA mRNA identified RNase III cleavage sites in the 5?-untranslated region of the corA mRNA. The introduction of nucleotide substitutions at the identified RNase III cleavage sites abolished RNase III cleavage activity on corA mRNA and resulted in prolonged half-lives of the mRNA, which demonstrates that RNase III cleavage constitutes a rate-determining step for corA mRNA degradation. These findings reveal an RNase III-mediated regulatory pathway that functions to modulate corA expression and, in turn, the influx of metal ions transported by CorA in E. coli. PMID:22343302

Lim, Boram; Sim, Se-Hoon; Sim, Minji; Kim, Kyungsub; Jeon, Che Ok; Lee, Younghoon; Ha, Nam-Chul

2012-01-01

311

Using bar codes for material control and accounting  

SciTech Connect

Modern computers have become an important part of almost all business operations, including nuclear material control and accountability (NMC&A). However the effectiveness of any computer hardware/software system is a function of the input data provided to it. To maximize the benefit from a computer, timely (ideally, real-time) and accurate data are required. This paper presents the benefits of using automatic data collection, and more specifically bar code technology. Bar coding is a simple and cost effective keyless data entry solution that has been widely adopted in world commerce and government agencies. Since its introduction to the first MINATOM facility in 1995, bar code activities at other facilities have increased. Tasks to integrate bar code technology with computerized MC&A, equipment, and training workshops have been an important part of the USDOE/MINATOM collaboration.

Weil, B.

1997-04-01

312

Integrated safeguards & security for material protection, accounting, and control.  

SciTech Connect

Traditional safeguards and security design for fuel cycle facilities is done separately and after the facility design is near completion. This can result in higher costs due to retrofits and redundant use of data. Future facilities will incorporate safeguards and security early in the design process and integrate the systems to make better use of plant data and strengthen both systems. The purpose of this project was to evaluate the integration of materials control and accounting (MC&A) measurements with physical security design for a nuclear reprocessing plant. Locations throughout the plant where data overlap occurs or where MC&A data could be a benefit were identified. This mapping is presented along with the methodology for including the additional data in existing probabilistic assessments to evaluate safeguards and security systems designs.

Duran, Felicia Angelica; Cipiti, Benjamin B.

2009-10-01

313

Radiological control criteria for materials considered for recycle and reuse  

SciTech Connect

Pacific Northwest Laboratory (PNL) is conducting technical analyses to support the US Department of Energy (DOE), Office of Environmental Guidance, Air, Water, and Radiation Division (DOE/EH-232) in developing radiological control criteria for recycling or reuse of metals or equipment containing residual radioactive contamination from DOE operations. The criteria, framed as acceptable concentrations for release of materials for recycling or reuse, are risk-based and were developed through analysis of generic radiation exposure scenarios and pathways. The analysis includes evaluation of relevant radionuclides, potential mechanisms of exposure, and non-health-related impacts of residual radioactivity on electronics and film. The analysis considers 42 key radionuclides that DOE operations are known to generate and that may be contained in recycled or reused metals or equipment. Preliminary results are compared with similar results reported by the International Atomic Energy Agency, by radionuclide grouping.

Kennedy, W.E. Jr.; Hill, R.L.; Aaberg, R.L. [Pacific Northwest Lab., Richland, WA (United States); Wallo, A. III [USDOE Assistant Secretary for Environment, Safety, and Health, Washington, DC (United States). Office of Environmental Guidance

1994-11-01

314

Urban-rural mortality differentials: controlling for material deprivation.  

PubMed

This paper investigates the relationship between premature mortality and material deprivation, and the differences in this relationship between urban and rural areas. We examine, given comparable measures of affluence or deprivation, whether residual differences exist between urban and rural areas for all-causes of death and, separately, for cancers, circulatory and respiratory diseases. Using 1990-92 mortality data for the 908 wards of Wales we apply statistical analyses based on tabular data and parametric Poisson regression models. Contrasts are sought between six urban and rural categories defined in terms of settlement sizes and the employment structure of rural areas. Inequalities in all-cause premature mortality are widest in the cities, narrowest in the deeper rural areas, and of intermediate and comparable value in other areas of Wales. This is largely a reflection of the different distributions of material deprivation in these areas. After controlling for differences in socio-economic characteristics, using deprivation measures, the tendency for lower mortality in deeper rural areas is substantially reduced. Residual mortality differences between urban and rural areas are shown to be dependent on the way deprivation is measured and the disease group under study. For cancers there are no residual mortality differences, while for respiratory and circulatory diseases some of the residual variation can be accounted for by employment variables, particularly previous employment in the coal mining industry. PMID:10832575

Senior, M; Williams, H; Higgs, G

2000-07-01

315

Restoring a Degraded Rangeland: Using Fire and Herbivory to Control Opuntia Cacti Encroachment  

E-print Network

Innovative restoration strategies are critically needed in the South Texas Plains for controlling increased Opuntia cacti invasions. Using a replicated and randomized experimental study, I have examined the effects of fire seasonality and herbivory...

Sosa, Gabriela

2011-02-22

316

In vitro degradation of amyloid material by four proteases in tissue of a patient with familial amyloidotic polyneuropathy.  

PubMed

The effects of 4 proteolytic enzymes, alpha-chymotrypsin, bromeline, collagenase, and lysozyme on amyloid tissue sections from a patient with familial amyloidotic polyneuropathy (FAP) were evaluated. Degradation of amyloid fibrils was significant with alpha-chymotrypsin, moderate with bromeline and collagenase, and slight with lysozyme. All of these proteases except collagenase are used as oral mucolytics in humans. The possibility of their clinical usefulness in the treatment or prevention of the development of FAP is discussed. PMID:2837542

Adachi, N; Koh, C S; Tsukada, N; Shoji, S; Yanagisawa, N

1988-04-01

317

10 CFR 74.33 - Nuclear material control and accounting for uranium enrichment facilities authorized to produce...  

Code of Federal Regulations, 2010 CFR

...false Nuclear material control and accounting for uranium enrichment facilities...CONTINUED) MATERIAL CONTROL AND ACCOUNTING OF SPECIAL NUCLEAR MATERIAL Special...33 Nuclear material control and accounting for uranium enrichment facilities...

2010-01-01

318

Framework for a flexible, real-time controller for automated material transport systems  

E-print Network

to control the MTS. A layout representation schema is proposed for describing the attributes of the material transport system layout. The material transport controller (MTC) is flexible because any dispatching, planning or scheduling algorithm can be "plugged...

Edlabadkar, Abhay

2012-06-07

319

78 FR 67225 - Amendments to Material Control and Accounting Regulations  

Federal Register 2010, 2011, 2012, 2013

...the use and management of radioactive materials. The MC&A requirements...and accounting, Nuclear materials, Packaging and containers, Radiation...and accounting, Nuclear materials, Packaging and containers,...

2013-11-08

320

Controlling the enzymatic digestion of lipids using hybrid nanostructured materials.  

PubMed

Solid nanoparticle-lipid hybrids have been engineered by using spray drying to assemble monodisperse hydrophilic silica nanoparticles and submicron lipid (triglyceride) emulsions together into composite microparticles, which have specific activity toward enzymes. The influence of silica particle size (100-1000 nm) and emulsifier type (anionic and cationic) on the three-dimensional structure of the composite particles was investigated. The nanostructure of the hybrid particles, which is controlled by the size of the voids between the closely packed silica particles, plays a critical role in lipase action and hence lipid digestion kinetics. Confining lipid droplets within the nanostructured silica aggregates led to 2- to 15-fold enhanced rate of lipolysis in comparison with dispersed coarse oil droplets. The composite particles were tailored to enhance, retain or sustain the lipolysis kinetics of submicron lipid emulsions. The presence of repulsive nanoparticle-droplet interactions favored aqueous redispersion and fast lipolysis of the hybrid composite materials, while attractive interactions hindered redispersion and delayed lipolysis of the confined lipid droplets. Such hybrid nanomaterials can be exploited to control the gastrointestinal enzymatic action and promisingly form the basis for the next generation of foods and medicines. PMID:25116477

Tan, Angel; Colliat-Dangus, Perrine; Whitby, Catherine P; Prestidge, Clive A

2014-09-10

321

Review of selected dynamic material control functions for international safeguards  

SciTech Connect

With the development of Dynamic Special Nuclear Material Accounting and Control systems used in nuclear manufacturing and reprocessing plants, there arises the question as to how these systems affect the IAEA inspection capabilities. The systems in being and under development provide information and control for a variety of purposes important to the plant operator, the safeguards purpose being one of them. This report attempts to judge the usefulness of these dynamic systems to the IAEA and have defined 12 functions that provide essential information to it. If the information acquired by these dynamic systems is to be useful to the IAEA, the inspectors must be able to independently verify it. Some suggestions are made as to how this might be done. But, even if it should not be possible to verify all the data, the availability to the IAEA of detailed, simultaneous, and plant-wide information would tend to inhibit a plant operator from attempting to generate a floating or fictitious inventory. Suggestions are made that might be helpful in the design of future software systems, an area which has proved to be fatally deficient in some systems and difficult in all.

Lowry, L.L.

1980-09-01

322

The effects of infrared laser and medical treatments on pain and serotonin degradation products in patients with myofascial pain syndrome. A controlled trial  

Microsoft Academic Search

In this controlled study of 46 patients with myofascial pain syndrome, we investigated the effects of infrared (IR) laser application to trigger points and medical treatment on pain reduction and serotonin and its degradation products. Retaining double-blind trial principles, the patients were randomly assigned to two groups. The treatment group received IR laser treatment, whereas the control group received sham

Yahya Ceylan; Sami Hizmetli; Yavuz Sili?

2004-01-01

323

Environmental controls on fungal community composition and abundance over 3 years in native and degraded shrublands.  

PubMed

Soil fungal communities have high local diversity and turnover, but the relative contribution of environmental and regional drivers to those patterns remains poorly understood. Local factors that contribute to fungal diversity include soil properties and the plant community, but there is also evidence for regional dispersal limitation in some fungal communities. We used different plant communities with different soil conditions and experimental manipulations of both vegetation and dispersal to distinguish among these factors. Specifically, we compared native shrublands with former native shrublands that had been disturbed or converted to pasture, resulting in soils progressively more enriched in carbon and nutrients. We tested the role of vegetation via active removal, and we manipulated dispersal by adding living soil inoculum from undisturbed native sites. Soil fungi were tracked for 3 years, with samples taken at ten time points from June 2006 to June 2009. We found that soil fungal abundance, richness, and community composition responded primarily to soil properties, which in this case were a legacy of plant community degradation. In contrast, dispersal had no effect on soil fungi. Temporal variation in soil fungi was partly related to drought status, yet it was much broader in native sites compared to pastures, suggesting some buffering due to the increased soil resources in the pasture sites. The persistence of soil fungal communities over 3 years in this study suggests that soil properties can act as a strong local environmental filter. Largely persistent soil fungal communities also indicate the potential for strong biotic resistance and soil legacies, which presents a challenge for both the prediction of how fungi respond to environmental change and our ability to manipulate fungi in efforts such as ecosystem restoration. PMID:24935902

Glinka, Clare; Hawkes, Christine V

2014-11-01

324

Organic acids for control of Salmonella in different feed materials  

PubMed Central

Background Salmonella control in animal feed is important in order to protect animal and public health. Organic acids is one of the control measures used for treatment of Salmonella contaminated feed or feed ingredients. In the present study, the efficacy of formic acid (FA) and different blends of FA, propionic acid (PA) and sodium formate (SF) was investigated. Four Salmonella strains isolated from feed were assayed for their acid tolerance. Also, the effect of lower temperatures (5°C and 15°C) compared to room temperature was investigated in rape seed and soybean meal. Results The efficacy of acid treatments varied significantly between different feed materials. The strongest reduction was seen in pelleted and compound mash feed (2.5 log10 reduction) followed by rapeseed meal (1 log10 reduction) after 5 days exposure. However, in soybean meal the acid effects were limited (less than 0.5 log10 reduction) even after several weeks’ exposure. In all experiments the survival curves showed a concave shape, with a fast initial death phase followed by reduction at a slower rate during the remaining time of the experiment. No difference in Salmonella reduction was observed between FA and a blend of FA and PA, whereas a commercial blend of FA and SF (Amasil) was slightly more efficacious (0.5-1 log10 reduction) than a blend of FA and PA (Luprocid) in compound mash feed. The Salmonella Infantis strain was found to be the most acid tolerant strain followed by, S. Putten, S. Senftenberg and S. Typhimurium. The tolerance of the S. Infantis strain compared with the S. Typhimurium strain was statistically significant (p<0.05). The lethal effect of FA on the S. Typhimurium strain and the S. Infantis strain was lower at 5°C and 15°C compared to room temperatures. Conclusions Acid treatment of Salmonella in feed is a matter of reducing the number of viable bacterial cells rather than eliminating the organism. Recommendations on the use of acids for controlling Salmonella in feed should take into account the relative efficacy of acid treatment in different feed materials, the variation in acid tolerance between different Salmonella strains, and the treatment temperature. PMID:23597100

2013-01-01

325

The Effects of Degraded Digital Instrumentation and Control Systems on Human-system Interfaces and Operator Performance: HFE Review Guidance and Technical Basis  

SciTech Connect

New and advanced reactors will use integrated digital instrumentation and control (I&C) systems to support operators in their monitoring and control functions. Even though digital systems are typically highly reliable, their potential for degradation or failure could significantly affect operator performance and, consequently, impact plant safety. The U.S. Nuclear Regulatory Commission (NRC) supported this research project to investigate the effects of degraded I&C systems on human performance and plant operations. The objective was to develop human factors engineering (HFE) review guidance addressing the detection and management of degraded digital I&C conditions by plant operators. We reviewed pertinent standards and guidelines, empirical studies, and plant operating experience. In addition, we conducted an evaluation of the potential effects of selected failure modes of the digital feedwater system on human-system interfaces (HSIs) and operator performance. The results indicated that I&C degradations are prevalent in plants employing digital systems and the overall effects on plant behavior can be significant, such as causing a reactor trip or causing equipment to operate unexpectedly. I&C degradations can impact the HSIs used by operators to monitor and control the plant. For example, sensor degradations can make displays difficult to interpret and can sometimes mislead operators by making it appear that a process disturbance has occurred. We used the information obtained as the technical basis upon which to develop HFE review guidance. The guidance addresses the treatment of degraded I&C conditions as part of the design process and the HSI features and functions that support operators to monitor I&C performance and manage I&C degradations when they occur. In addition, we identified topics for future research.

O'Hara, J.M.; W. Gunther, G. Martinez-Guridi

2010-02-26

326

46 CFR 128.240 - Hydraulic or pneumatic power and control-materials and pressure design.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Hydraulic or pneumatic power and control-materials...Materials and Pressure Design § 128.240 Hydraulic or pneumatic power and control—materials...flanges, and standard valves) for hydraulic or pneumatic power and control...

2010-10-01

327

Federal Automated Information System of Nuclear Material Control and Accounting: Uniform System of Reporting Documents  

Microsoft Academic Search

One of the fundamental regulations of the Russian State System for Nuclear Material Accounting and Control (SSAC), ''Basic Nuclear Material Control and Accounting Rules,'' directed that a uniform report system be developed to support the operation of the SSAC. According to the ''Regulation on State Nuclear Material Control and Accounting,'' adopted by the Russian Federation Government, Minatom of Russia is

M V Pitel; L Kasumova; R A Babcock; C Heinberg

2003-01-01

328

Controlled release of plasmid DNA from cationized gelatin hydrogels based on hydrogel degradation  

Microsoft Academic Search

This paper shows achievement of the in vivo controlled release of a plasmid DNA from a biodegradable hydrogel and the consequent regulation of gene expression period. Cationization of gelatin was preformed through introduction of ethylenediamine and the gelatin prepared was crosslinked by various concentrations of glutaraldehyde to obtain cationized gelatin (CG) hydrogels as the carrier of plasmid DNA. In vivo

Yasunori Fukunaka; Kazunori Iwanaga; Kazuhiro Morimoto; Masawo Kakemi; Yasuhiko Tabata

2002-01-01

329

Programme and abstracts. Workshop on Expert Evaluation and Control of Compound Semiconductor Materials and Technologies No. 1: (EXAMTEC 199)  

NASA Astrophysics Data System (ADS)

This workshop included the following topics: Performance and Reliability of Micro-Optoelectronic Devices in Connection with Material Properties and Process Conditions; Material Related Issues and their Characterization in View of III-V Heterojunction Device Optimization; Material Problems for the Development of InGaAs/InAlAs HEMT's Technology; Theoretical and Experimental Study of Failure Mechanisms in RF Reliability Life Tested HEMT's; A Study of Detrimental Transient Effects in GaAs HEMT's; Relating Micron Wave Mapped Data to Physical Parameters for MODFET's; Performance and Reliability of Micro-Optoelectronic Devices in Connection with Material Properties and Process Conditions; Material Related Reliability Aspects of III-V Optical Devices; A Possible Origin of Degradation Mechanisms in AlGaAs/GaAs Laser-Like Structures; Thermal Stability of Pseudomorphic HEMT's; Detailed Process Analysis for Controlling the Yield of GaAs MMIC's Technology; Spatially Resolved Photoluminescence Techniques Applied to the Control of InGaAsP/InP Laser Processing; Growth and Characterization of Epitaxial Structures; Atomic Ordering and Phase Separations in Compound Semiconductors and their Effect on Device Behavior; Improved Device Quality by Strained Layer Epitaxy; II-VI Semiconductor Strained Heterostructures: A Structural Review; and Interface Properties of Strained InGaAs/InP Quantum Wells Grown by LP-MOVPE.

1992-05-01

330

Control of RNase E-mediated RNA degradation by 5'-terminal base pairing in E. coil  

Microsoft Academic Search

DESPITE the variety of messenger RNA half-lives in bacteria (0.5-30 min in Escherichia coli) and their importance in controlling gene expression, their molecular basis remains obscure. The life-time of an entire mRNA molecule can be determined by features near its 5' end, but no 5' exoribonuclease has been identified in any prokaryotic organism1-6. A mutation that inactivates E. coli RNase

Philippe Bouvet; Joel G. Belasco

1992-01-01

331

Tubular structured hierarchical mesoporous titania material derived from natural cellulosic substances and application as photocatalyst for degradation of methylene blue  

SciTech Connect

Graphical abstract: Bio-inspired, tubular structured hierarchical mesoporous titania material with high photocatalytic activity under UV light was fabricated employing natural cellulosic substance (cotton) as hard template and cetyltrimethylammonium bromide (CTAB) surfactant as soft template using a one-pot sol-gel method. Highlights: {yields} Tubular structured mesoporous titania material was fabricated by sol-gel method. {yields} The titania material faithfully recorded the hierarchical structure of the template substrate (cotton). {yields} The titania material exhibited high photocatalytic activity in decomposition of methylene blue. -- Abstract: Bio-inspired, tubular structured hierarchical mesoporous titania material was designed and fabricated employing natural cellulosic substance (cotton) as hard template and cetyltrimethylammonium bromide (CTAB) surfactant as soft template by one-pot sol-gel method. The tubular structured hierarchical mesoporous titania material processes large specific surface area (40.23 m{sup 2}/g) and shows high photocatalytic activity in the photodegradation of methylene blue under UV light irradiation.

Huang, Haiqing [Key Laboratory of Radioactive Geology and Exploration Technology Fundamental Science for National Defense, East China Institute of Technology, Fuzhou, Jiangxi 344000 (China)] [Key Laboratory of Radioactive Geology and Exploration Technology Fundamental Science for National Defense, East China Institute of Technology, Fuzhou, Jiangxi 344000 (China); Liu, Xiaoyan [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China)] [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Huang, Jianguo, E-mail: jghuang@zju.edu.cn [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China)] [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

2011-11-15

332

A Degrading Experience  

NSDL National Science Digital Library

In this activity, learners perform an experiment to learn about how different types of marine debris degrade and how weather and sunlight affect the rate of degradation. Learners discover that debris made from natural materials, while biodegradable, can still be considered pollutants and can still harm the marine environment.

Sheavly, Seba; Reigster, Katie

2014-05-28

333

Method of controlling coherent synchroton radiation-driven degradation of beam quality during bunch length compression  

DOEpatents

A method of avoiding CSR induced beam quality defects in free electron laser operation by a) controlling the rate of compression and b) using a novel means of integrating the compression with the remainder of the transport system: both are accomplished by means of dispersion modulation. A large dispersion is created in the penultimate dipole magnet of the compression region leading to rapid compression; this large dispersion is demagnified and dispersion suppression performed in a final small dipole. As a result, the bunch is short for only a small angular extent of the transport, and the resulting CSR excitation is small.

Douglas, David R. (Newport News, VA); Tennant, Christopher D. (Williamsburg, VA)

2012-07-10

334

Application of telerobotic control to remote processing of nuclear material  

SciTech Connect

In processing radioactive material there are certain steps which have customarily required operators working at glove box enclosures. This can subject the operators to low level radiation dosages and the risk of accidental contamination, as well as generate significant radioactive waste to accommodate the human interaction. An automated system is being developed to replace the operator at the glove box and thus remove the human from these risks, and minimize waste. Although most of the processing can be automated with very little human operator interaction, there are some tasks where intelligent intervention is necessary to adapt to unexpected circumstances and events. These activities will require that the operator be able to interact with the process using a remote manipulator in a manner as natural as if the operator were actually in the work cell. This robot-based remote manipulation system, or telerobot, must provide the operator with an effective means of controlling the robot arm, gripper and tools. This paper describes the effort in progress in Lawrence Livermore National Laboratory to achieve this capability. 8 refs.

Merrill, R.D.; Grasz, E.L.; Herget, C.J.; Gavel, D.T.; Addis, R.B.; DeMinico, G.A.

1991-07-08

335

Bleed water testing program for controlled low strength material  

SciTech Connect

Bleed water measurements for two Controlled Low Strength Material (CLSM) mixes were conducted to provide engineering data for the Tank 20F closure activities. CLSM Mix 1 contained 150 pounds of cement per cubic yard whereas CLSM Mix 2 contained 50 pounds per cub yard. SRS currently used CLSM Mix 2 for various applications. Bleed water percentages and generation rates were measured along with flow and compressive strength. This information will be used to select a mix design for the Tank 20F closure activities and to establish the engineering requirements, such as, lift height, time required between lifts and quantity of bleed water to be removed from the tank during the placement activities. Mix 1 is recommended for placement within Tank 20F because it has better flow characteristics, less segregation, lower percentage of bleed water and slightly higher strength. Optimization of Mix 1 was beyond the scope of this study. However, further testing of thickening additives, such as clays (bentonite), sodium silicate or fine silicas maybe useful for decreasing or eliminating bleed water.

Langton, C.A.

1996-11-12

336

Controllable electrodeposition of ZnO nanorod arrays on flexible stainless steel mesh substrate for photocatalytic degradation of Rhodamine B  

NASA Astrophysics Data System (ADS)

Well-aligned single-crystalline ZnO nanorod arrays (ZNRAs) were prepared on flexible stainless steel mesh (SSM) substrate in large-scale by using a direct electrodeposition method. The effects of electrochemical parameters, such as applied potential, applied nucleation potential time, substrate pretreatment, electrodeposition duration and times, on the orientation, morphology and density of ZNRAs were systematically studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and the selected area electron diffraction (SAED). The results showed that ZNRAs on SSM substrate with [0 0 1] preferred orientation and well crystallization were obtained by controlling the applied potential in the range of -0.9 to -1.1 V. The density of ZNRAs could be increased obviously by applying a nucleation potential (-1.3 V for more than 10 s before deposition) or by means of substrate pretreatment (the SSM immersed in zinc acetate colloid for more than 10 min before deposition), meanwhile, the deposited ZNRAs also had small average diameter (<46 ± 4 nm), narrow size distribution and good orientation. In addition, it was also found that the average diameter of ZNRAs could be increased from 89 to 201 ± 5 nm by extending the electrodeposition duration from 1800 to 7200 s, and the length of rods was from 0.8 to 2.2 ± 0.1 ?m when the times of the electrodeposition from one to six times. Furthermore, the band gap energy (Eg) of as-prepared ZNTAs was not closely related to the electrodeposition times (only changed from 3.30 to 3.32 eV). The ZNRAs prepared with more electrodeposition times showed enhanced photocatalytic performance under the UV-lamp for degradation of Rhodamine B. The degradation efficiency of ZNRAs improved from 89.4% to 98.3% with the deposition times from one to six times.

Lu, Hui; Zhang, Mei; Guo, Min

2014-10-01

337

Heme Exporter FLVCR1a Regulates Heme Synthesis and Degradation and Controls Activity of Cytochromes P450  

PubMed Central

Background & Aims The liver has one of the highest rates of heme synthesis of any organ. More than 50% of the heme synthesized in the liver is used for synthesis of P450 enzymes, which metabolize exogenous and endogenous compounds that include natural products, hormones, drugs, and carcinogens. Feline leukemia virus subgroup C cellular receptor 1a (FLVCR1a) is plasma membrane heme exporter that is ubiquitously expressed and controls intracellular heme content in hematopoietic lineages. We investigated the role of Flvcr1a in liver function in mice. Methods We created mice with conditional disruption of Mfsd7b, which encodes Flvcr1a, in hepatocytes (Flvcr1afl/fl;alb-cre mice). Mice were analyzed under basal conditions, after phenylhydrazine-induced hemolysis, and after induction of cytochromes P450 synthesis. Livers were collected and analyzed by histologic, quantitative real-time polymerase chain reaction, and immunoblot analyses. Hepatic P450 enzymatic activities were measured. Results Flvcr1afl/fl;alb-cre mice accumulated heme and iron in liver despite up-regulation of heme oxygenase 1, ferroportin, and ferritins. Hepatic heme export activity of Flvcr1a was closely associated with heme biosynthesis, which is required to sustain cytochrome induction. Upon cytochromes P450 stimulation, Flvcr1afl/fl;alb-cre mice had reduced cytochrome activity, associated with accumulation of heme in hepatocytes. The expansion of the cytosolic heme pool in these mice was likely responsible for the early inhibition of heme synthesis and increased degradation of heme, which reduced expression and activity of cytochromes P450. Conclusions In livers of mice, Flvcr1a maintains a free heme pool that regulates heme synthesis and degradation as well as cytochromes P450 expression and activity. These findings have important implications for drug metabolism. PMID:24486949

Vinchi, Francesca; Ingoglia, Giada; Chiabrando, Deborah; Mercurio, Sonia; Turco, Emilia; Silengo, Lorenzo; Altruda, Fiorella; Tolosano, Emanuela

2014-01-01

338

Effects of Heating on Teflon(Registered Trademark) FEP Thermal Control Material from the Hubble Space Telescope  

NASA Technical Reports Server (NTRS)

Metallized Teflon(Registered Trademark) FEP (fluorinated ethylene propylene) thermal control material on the Hubble Space Telescope (HST) is degrading in the space environment. Teflon(Registered Trademark) FEP thermal control blankets (space-facing FEP) retrieved during the first servicing mission (SM1) were found to be embrittled on solar facing surfaces and contained microscopic cracks. During the second servicing mission (SM2) astronauts noticed that the FEP outer layer of the multi-layer insulation (MLI) covering the telescope was cracked in many locations around the telescope. Large cracks were observed on the light shield, forward shell and equipment bays. A tightly curled piece of cracked FEP from the light shield was retrieved during SM2 and was severely embrittled, as witnessed by ground testing. A Failure Review Board (FRB) was organized to determine the mechanism causing the MLI degradation. Density, x-ray crystallinity and solid state nuclear magnetic resonance (NMR) analyses of FEP retrieved during SM1 were inconsistent with results of FEP retrieved during SM2. Because the retrieved SM2 material curled while in space, it experienced a higher temperature extreme during thermal cycling, estimated at 200 C, than the SM1 material, estimated at 50 C. An investigation on the effects of heating pristine and FEP exposed on HST was therefore conducted. Samples of pristine. SM1, and SM2 FEP were heated to 200 C and evaluated for changes in density and morphology. Elevated temperature exposure was found to have a major impact on the density of the retrieved materials. Characterization of polymer morphology of as-received and heated FEP samples by NMR provided results that were consistent with the density results. These findings have provided insight to the damage mechanisms of FEP in the space environment.

deGroh, Kim; Gaier, James R.; Hall, Rachelle L.; Norris, Mary Jo; Espe, Matthew P.; Cato, Daveen R.

1999-01-01

339

Radiation Induced Degradation of the White Thermal Control Paints Z-93 and Z-93P  

NASA Technical Reports Server (NTRS)

This paper details a comparison analysis of the zinc oxide pigmented white thermal control paints Z-93 and Z-93P. Both paints were simultaneously exposed to combined space environmental effects and analyzed using an in-vacuo reflectance technique. The dose applied to the paints was approximately equivalent to 5 years in a geosynchronous orbit. This comparison analysis showed that Z-93P is an acceptable substitute for Z-93. Irradiated samples of Z-93 and Z-93P were subjected to additional exposures of ultraviolet (UV) radiation and analyzed using the in-vacuo reflectance technique to investigate UV activated reflectance recovery. Both samples showed minimal UV activated reflectance recovery after an additional 190 equivalent sun hour (ESH) exposure. Reflectance response utilizing nitrogen as a repressurizing gas instead of air was also investigated. This investigation found the rates of reflectance recovery when repressurized with nitrogen are slower than when repressurized with air.

Edwards, D. L.; Zwiener, J. M.; Wertz, G. E.; Vaughn, J. A.; Kamenetzky, R. R.; Finckenor, M. M.; Meshishnek, M. J.

1996-01-01

340

Tags and seals for controling nuclear materials, Arms control and nonproliferation technologies. Second quarter 1993  

SciTech Connect

This issue of Arms Control and Nonproliferation Technologies summarizes demonstrations and addresses related topics. The first article, ``Basic Nuclear Material Control and Accountability Concepts as Might be Applied to the Uranium from the US-Russian HEU Purchase,`` describes safeguards sybsystems necessary for effective nuclear material safeguards. It also presents a general discussion on HEU-to-low-enrichment uranium (LEU) commingling processes and suggests applicable key measurement points. The second article, ``A Framework for Evaluating Tamper-Indicating-Device Technologies (TIDs),`` describes their uses, proper selection, and evaluation. The final three articles discuss the tags and seals applications and general characteristics of several nuclear material containers: the Type 30B uranium hexafluoride container, the AT-400R container, and the DOT Specification 6M container for SNM. Finally, the Appendix displays short descriptions and illustrations of seven tags and seals, including: the E-cup and wire seal, the python seal, the secure loop inspectable tag/seal (SLITS), bolt-and-loop type electronic identification devices, and the shrink-wrap seal.

Staehle, G; Talaber, C; Stull, S; Moulthrop, P [eds.

1993-12-31

341

Schwann cell-derived Apolipoprotein D controls the dynamics of post-injury myelin recognition and degradation  

PubMed Central

Management of lipids, particularly signaling lipids that control neuroinflammation, is crucial for the regeneration capability of a damaged nervous system. Knowledge of pro- and anti-inflammatory signals after nervous system injury is extensive, most of them being proteins acting through well-known receptors and intracellular cascades. However, the role of lipid binding extracellular proteins able to modify the fate of lipids released after injury is not well understood. Apolipoprotein D (ApoD) is an extracellular lipid binding protein of the Lipocalin family induced upon nervous system injury. Our previous study shows that axon regeneration is delayed without ApoD, and suggests its participation in early events during Wallerian degeneration. Here we demonstrate that ApoD is expressed by myelinating and non-myelinating Schwann cells and is induced early upon nerve injury. We show that ApoD, known to bind arachidonic acid (AA), also interacts with lysophosphatidylcholine (LPC) in vitro. We use an in vivo model of nerve crush injury, a nerve explant injury model, and cultured macrophages exposed to purified myelin, to uncover that: (i) ApoD regulates denervated Schwann cell-macrophage signaling, dampening MCP1- and Tnf-dependent macrophage recruitment and activation upon injury; (ii) ApoD controls the over-expression of the phagocytosis activator Galectin-3 by infiltrated macrophages; (iii) ApoD controls the basal and injury-triggered levels of LPC and AA; (iv) ApoD modifies the dynamics of myelin-macrophage interaction, favoring the initiation of phagocytosis and promoting myelin degradation. Regulation of macrophage behavior by Schwann-derived ApoD is therefore a key mechanism conditioning nerve injury resolution. These results place ApoD as a lipid binding protein controlling the signals exchanged between glia, neurons and blood-borne cells during nerve recovery after injury, and open the possibility for a therapeutic use of ApoD as a regeneration-promoting agent.

García-Mateo, Nadia; Ganfornina, Maria D.; Montero, Olimpio; Gijón, Miguel A.; Murphy, Robert C.; Sanchez, Diego

2014-01-01

342

Performance of thermal control tape in the protection of composite materials to space environmental exposure  

NASA Technical Reports Server (NTRS)

Thermal control tape flown on the Long Duration Exposure Facility (LDEF) experiment A0171 has shown to be effective in protecting epoxy fiberglass composites from atomic oxygen and ultraviolet degradation. The tape adhesive performed well. The aluminum, however, appeared to have become embrittled by the 5.8 years of space radiation exposure.

Kamenetzky, R. R.; Whitaker, A. F.

1992-01-01

343

Controls on methane released through ebullition in peatlands affected by permafrost degradation  

NASA Astrophysics Data System (ADS)

thaw in peat plateaus leads to the flooding of surface soils and the formation of collapse scar bogs, which have the potential to be large emitters of methane (CH4) from surface peat as well as deeper, previously frozen, permafrost carbon (C). We used a network of bubble traps, permanently installed 20 cm and 60 cm beneath the moss surface, to examine controls on ebullition from three collapse bogs in interior Alaska. Overall, ebullition was dominated by episodic events that were associated with changes in atmospheric pressure, and ebullition was mainly a surface process regulated by both seasonal ice dynamics and plant phenology. The majority (>90%) of ebullition occurred in surface peat layers, with little bubble production in deeper peat. During periods of peak plant biomass, bubbles contained acetate-derived CH4 dominated (>90%) by modern C fixed from the atmosphere following permafrost thaw. Post-senescence, the contribution of CH4 derived from thawing permafrost C was more variable and accounted for up to 22% (on average 7%), in the most recently thawed site. Thus, the formation of thermokarst features resulting from permafrost thaw in peatlands stimulates ebullition and CH4 release both by creating flooded surface conditions conducive to CH4 production and bubbling as well as by exposing thawing permafrost C to mineralization.

Klapstein, Sara J.; Turetsky, Merritt R.; McGuire, A. David; Harden, Jennifer W.; Czimczik, Claudia I.; Xu, Xiaomei; Chanton, Jeffrey P.; Waddington, James M.

2014-03-01

344

U.S./Russian materials protection, control and accounting program efforts at the Institute of Inorganic Materials  

SciTech Connect

The All-Russian Scientific Research Institute of Inorganic Materials (VNIINM) performs research in nuclear power reactor fuel, spent fuel reprocessing and waste management, materials science of fissionable and reactor structural materials, metallurgy, superconducting materials, and analytical sciences. VNIINM supports the Ministry of Atomic Energy of the Russian Federation (MINATOM) in technologies for fabrication and processing of nuclear fuel. As a participant in the U.S./Russian nuclear materials protection, control and accounting (MPC&A) program, VNIINM is providing support for measurements of nuclear materials in bulk forms by developing specifications, test and evaluation, certification, and implementation of measurement methods for such materials. In 1997, VNIINM worked with Brookhaven staff in developing and documenting material control and accounting requirements for nuclear materials in bulk form, Livermore and Los Alamos staff in testing and evaluating gamma-ray spectrometry methods for bulk materials, Los Alamos staff in test and evaluation of neutron-coincidence counting techniques, Livermore and Oak Ridge staff in upgrading VNIINM'S mass-spectrometry laboratory, Pacific Northwest staff on automating VNIINM's coulometric titration system and starting a task to develop a general MC&A plan for the VNHNM site, Los Alamos staff in developing a computerized accounting system for nuclear material within VNHNM and their storage facility, and Los Alamos and Oak Ridge staff in developing a bar-code system to complement the computerized accounting system. Our paper will describe the status of this work in 1997.

Ruhter, W. D., LLNL

1997-09-01

345

Materials Testing and Quality Control Soils, 3-28. Military Curriculum Materials for Vocational and Technical Education.  

ERIC Educational Resources Information Center

This instructional package on material testing and quality control of soils has been adapted from military curriculum materials for use in technical and vocational education programs. This short course presents basic information on soils as well as exploration, field identification, and laboratory procedures that will enable students completing…

Ohio State Univ., Columbus. National Center for Research in Vocational Education.

346

10 CFR 74.51 - Nuclear material control and accounting for strategic special nuclear material.  

Code of Federal Regulations, 2010 CFR

...for strategic special nuclear material. (a...of strategic special nuclear material (SSNM) and...site, other than a nuclear reactor licensed pursuant...and (5) Timely generation of information to...

2010-01-01

347

Commonly observed degradation in field-aged photovoltaic modules  

Microsoft Academic Search

Degradation leading to failure in photovoltaic modules follows a progression that is dependent on multiple factors, some of which interact causing degradation that is difficult to simulate in the lab. This paper defines observed degradation in field-aged modules, including degradation of packaging materials, adhesional loss, degradation of interconnects, degradation due to moisture intrusion, and semiconductor device degradation. Additionally, this paper

M. A. Quintana; D. L. King; T. J. McMahon; C. R. Osterwald

2002-01-01

348

46 CFR 128.240 - Hydraulic or pneumatic power and control-materials and pressure design.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Hydraulic or pneumatic power and control-materials and pressure...Pressure Design § 128.240 Hydraulic or pneumatic power and control—materials and pressure...and standard valves) for hydraulic or pneumatic power and control systems must...

2013-10-01

349

46 CFR 128.240 - Hydraulic or pneumatic power and control-materials and pressure design.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Hydraulic or pneumatic power and control-materials and pressure...Pressure Design § 128.240 Hydraulic or pneumatic power and control—materials and pressure...and standard valves) for hydraulic or pneumatic power and control systems must...

2012-10-01

350

Application of -Synthesis based H-Control for Adaptive Optics in Laser Material Processing  

E-print Network

Application of µ-Synthesis based H-Control for Adaptive Optics in Laser Material Processing Steffen Mauch1 and Johann Reger1 Abstract-- An adaptive optics system is used for the con- trolled attenuation-- adaptive optics, robust control, H-control, material processing, µ-synthesis I. INTRODUCTION As the costs

Knobloch,Jürgen

351

Degradation of simazine from aqueous solutions by diatomite-supported nanosized zero-valent iron composite materials.  

PubMed

A novel composite material based on deposition of nanosized zero-valent iron (nZVI) particles on acid-leached diatomite was synthesised for the removal of a chlorinated contaminant in water. The nZVI/diatomite composites were characterised by X-ray diffraction, scanning electron microscopy, elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. Compared with the pure nZVI particles, better dispersion of nZVI particles on the surface or inside the pores of diatom shells was observed. The herbicide simazine was selected as the model chlorinated contaminant and the removal efficiency by nZVI/diatomite composite was compared with that of the pristine nZVI and commercial iron powder. It was found that the diatomite supported nZVI composite material prepared by centrifugation exhibits relatively better efficient activity in decomposition of simazine than commercial Fe, lab synthesised nZVI and composite material prepared via rotary evaporation, and the optimum experimental conditions were obtained based on a series of batch experiments. This study on immobilising nZVI particles onto diatomite opens a new avenue for the practical application of nZVI and the diatomite-supported nanosized zero-valent iron composite materials have potential applications in environmental remediation. PMID:24231330

Sun, Zhiming; Zheng, Shuilin; Ayoko, Godwin A; Frost, Ray L; Xi, Yunfei

2013-12-15

352

Magnetically controlled shape memory alloys: A new class of actuator materials  

NASA Astrophysics Data System (ADS)

Materials that develop large strokes under precise and rapid control exhibit a great potential in mechanical engineering. Actuators made from those kinds of materials could replace hydraulic, pneumatic, and electromagnetic drives in many applications. However, no such materials are available to date. Piezoelectric and magnetostrictive materials exhibit rapid response, but their strokes are small. In shape memory alloys, strokes are large, but their control is slow due to thermomechanical control. Magnetic control of the shape memory effect was recently suggested by the present author for a principle of new kinds of actuator materials. These materials can develop strains of several percent, and their control is rapid and precise. Actuation of these materials is based on the reorienting of the twin structure of martensite or the motion of austenite-martensite interfaces by applied magnetic field. In the present report, magnetically induced motion of the austenite-martensite interfaces is demonstrated in an Fe-33.5Ni alloy.

Ullakko, K.

1996-06-01

353

36 CFR 401.5 - Control and supervision of materials, design, and building.  

Code of Federal Regulations, 2010 CFR

...supervision of materials, design, and building. 401.5 Section 401.5 ...supervision of materials, design, and building. The Commission controls the design and prescribes regulations for the building of all memorial monuments and...

2010-07-01

354

Thermal degradation and polymerization of carbonaceous materials in a metapelite granitoid magma system in the Ryoke metamorphic belt, SW Japan  

NASA Astrophysics Data System (ADS)

Some granitoid magmas in subduction zones are closely related to sedimentary rocks, due to partial melting or assimilation during generation and ascent. In the Ryoke high temperature ( T)-low pressure ( P) metamorphic belt of SW Japan, syngenetic carbonaceous material containing organic matter occurs in granodiorite which interacted with pelitic rocks under middle crust T and P conditions. Solid state carbonaceous materials in metapelites, injection gneiss, and granodiorite consist of graphite and organic matter. X-ray mapping by EPMA shows that granular carbonaceous material a few tens of microns in diameter consisting of C with or without N, Cl, and S occurs as inclusions in quartz, feldspar, biotite, and garnet. Micro laser Raman spectro-analysis shows that some carbonaceous inclusions in injection gneiss and metapelite are graphite. Peaks characteristic of phenyl-H, alkyl-CH 3, -CH 2-, C dbnd O, and -C dbnd C- stretching vibrations are present in FT-IR spectra of biotite flakes, indicating that hydrocarbon compounds are uniformly distributed in the crystal structure and/or along cleavages of that mineral. Particulate carbonaceous materials in minerals in the granodiorite contain long-aliphatic hydrocarbon bonds, oxygen-bearing organic compounds, and aromatic fragments. The distribution of these organic groups differs among feldspar, quartz, and biotite. Carbon isotopic ratios in the granodiorite are lighter than those of graphite and amorphous carbon in the metapelite, suggesting an origin from low molecular weight hydrocarbons released from the metapelite. Carbonaceous materials probably formed by hydrocarbon polymerization and solidification of gaseous hydrocarbons were trapped in the highly viscous granodiorite magma during crystallization and cooling, and under differing oxidation conditions. The presence of such organic matter in granitoids is important for the understanding of the behavior and circulation of volatile components in arc systems during subduction, accretion, and magmatism.

Sawada, Yoshihiro; Sampei, Yoshikazu; Hada, Osamu; Taguchi, Sachihiro

2008-06-01

355

Stability control of valerian ground material and extracts: a new HPLC-method for the routine quantification of valerenic acids and lignans.  

PubMed

A new HPLC-method for the separation of medium polar and nonpolar compounds in preparations of Valeriana officinalis was established for stability control. Powdered valerian root and a commercial ethanolic valerian extract were investigated for apparent differences in stability behaviour. Storage conditions were chosen according to the ICH-guidelines. Changes in composition of valerenic acids and lignans were observed depending on storage conditions and packaging materials. Hydroxyvalerenic acid, pinoresinol and hydroxypinoresinol were identified as degradation products in Valerian root, especially during accelerated testing. Ethanolic extracts appeared not to be as sensitive for chemical degradation under climatic influences compared to the crude plant material, and showed no increase in the amounts of lignan-aglyka. In comparison, extracts showed high sensitivity on changes of physical properties like loss on drying and viscosity. PMID:15248459

Goppel, M; Franz, G

2004-06-01

356

Methods of measurement for semiconductor materials, process control, and devices  

NASA Technical Reports Server (NTRS)

Significant accomplishments include development of a procedure to correct for the substantial differences of transistor delay time as measured with different instruments or with the same instrument at different frequencies; association of infrared response spectra of poor quality germanium gamma ray detectors with spectra of detectors fabricated from portions of a good crystal that had been degraded in known ways; and confirmation of the excellent quality and cosmetic appearance of ultrasonic bonds made with aluminum ribbon wire. Work is continuing on measurement of resistivity of semiconductor crystals; study of gold-doped silicon, development of the infrared response technique; evaluation of wire bonds and die attachment; and measurement of thermal properties of semiconductor devices, delay time and related carrier transport properties in junction devices, and noise properties of microwave diodes.

Bullis, W. M. (editor)

1972-01-01

357

Nanotechnology in environmental remediation: degradation of volatile organic compounds (VOCs) over visible-light-active nanostructured materials.  

PubMed

Volatile organic compounds (VOCs) are major pollutants and are considered to be one of the most important contaminants generated by human beings living in urban and industrial areas. Methyl tert-butyl ether (MTBE) is a VOC that has been widely used as a gasoline additive to reduce VOC emissions from motor vehicles. However, new gasoline additives like MTBE are having negative environmental impacts. Recent survey reports clearly show that groundwater is often polluted owing to leakage of petroleum products from underground storage tanks. MTBE is highly soluble in water (e.g., 0.35-0.71 M) and has been detected at high concentrations in groundwater. The presence of MTBE in groundwater poses a potential health problem. The documented effects of MTBE exposure are headaches, vomiting, diarrhea, fever, cough, muscle aches, sleepiness, disorientation, dizziness, and skin and eye irritation. To address these problems, photocatalytic treatment is the preferred treatment for polluted water. In the present work, a simple and template-free solution phase synthesis method has been developed for the preparation of novel cadmium sulfide (CdS) hollow microspheres using cadmium nitrate and thioacetamide precursors. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction, high-resolution scanning electron microscopy (HR-SEM), X-ray photoelectron spectroscopy, and UV-visible diffused reflectance spectroscopy. The HR-SEM measurements revealed the spherical morphology of the CdS microspheres, which evolved by the oriented aggregation of the primary CdS nanocrystals. Furthermore, studies of photocatalytic activity revealed that the synthesized CdS hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading MTBE in aqueous solution under visible light illumination. These results suggest that CdS microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light radiation. PMID:24566352

Selvaraj, Rengaraj; Al-Kindy, Salma M Z; Silanpaa, Mika; Kim, Younghun

2014-01-01

358

Acoustical characterization and parameter optimization of polymeric noise control materials  

NASA Astrophysics Data System (ADS)

The sound transmission loss (STL) characteristics of polymer-based materials are considered. Analytical models that predict, characterize and optimize the STL of polymeric materials, with respect to physical parameters that affect performance, are developed for single layer panel configuration and adapted for layered panel construction with homogenous core. An optimum set of material parameters is selected and translated into practical applications for validation. Sound attenuating thermoplastic materials designed to be used as barrier systems in the automotive and consumer industries have certain acoustical characteristics that vary in function of the stiffness and density of the selected material. The validity and applicability of existing theory is explored, and since STL is influenced by factors such as the surface mass density of the panel's material, a method is modified to improve STL performance and optimize load-bearing attributes. An experimentally derived function is applied to the model for better correlation. In-phase and out-of-phase motion of top and bottom layers are considered. It was found that the layered construction of the co-injection type would exhibit fused planes at the interface and move in-phase. The model for the single layer case is adapted to the layered case where it would behave as a single panel. Primary physical parameters that affect STL are identified and manipulated. Theoretical analysis is linked to the resin's matrix attribute. High STL material with representative characteristics is evaluated versus standard resins. It was found that high STL could be achieved by altering materials' matrix and by integrating design solution in the low frequency range. A suggested numerical approach is described for STL evaluation of simple and complex geometries. In practice, validation on actual vehicle systems proved the adequacy of the acoustical characterization process.

Homsi, Emile N.

2003-10-01

359

Microbial population in the biomass adhering to supporting material in a packed-bed reactor degrading organic solid waste  

Microsoft Academic Search

An anaerobic packed-bed reactor using carbon fiber textiles (CFT) as the supporting material was continuously operated using\\u000a an artificial garbage slurry. 16S rRNA gene analysis showed that many bacteria in the biomass adhering to CFT were closely\\u000a related to those observed from other anaerobic environments, although a wide variety of unidentified bacteria were also found.\\u000a Dot blot hybridization results clarified

Kengo Sasaki; Shin Haruta; Yoshiyuki Ueno; Masaharu Ishii; Yasuo Igarashi

2007-01-01

360

Effect of low initial envelope material moisture content on swine tissue degradation in layered livestock mortality composting systems  

Microsoft Academic Search

A 12-week laboratory study was conducted to assess the minimum initial moisture content of compost bulking (envelope) materials necessary to sustain desired heat production and completion of carcass decomposition during emergency composting of swine carcasses. During full-scale field testing of a semi-enclosed emergency composting procedure, first developed and used by the Canadian Food Inspection Agency during an avian influenza outbreak

Benjamin P. Crawford

2009-01-01

361

Degradation mechanisms and accelerated aging test design  

SciTech Connect

The fundamental mechanisms underlying the chemical degradation of polymers can change as a function of environmental stress level. When this occurs, it greatly complicates any attempt to use accelerated tests for predicting long-term material degradation behaviors. Understanding how degradation mechanisms can change at different stress levels facilitates both the design and the interpretation of aging tests. Oxidative degradation is a predominant mechanism for many polymers exposed to a variety of different environments in the presence of air, and there are two mechanistic considerations which are widely applicable to material oxidation. One involves a physical process, oxygen diffusion, as a rate-limiting step. This mechanism can predominate at high stress levels. The second is a chemical process, the time-dependent decomposition of peroxide species. This leads to chain branching and can become a rate-controlling factor at lower stress levels involving time-scales applicable to use environments. The authors describe methods for identifying the operation of these mechanisms and illustrate the dramatic influence they can have on the degradation behaviors of a number of polymer types. Several commonly used approaches to accelerated aging tests are discussed in light of the behaviors which result from changes in degradation mechanisms. 9 references, 4 figures.

Clough, R L; Gillen, K T

1985-01-01

362

Mechanisms of polymer degradation and erosion  

Microsoft Academic Search

The most important features of the degradation and erosion of degradable polymers in vitro are discussed. Parameters of chemical degradation, which is the scission of the polymer backbone, are described such as the type of polymer bond, pH and copolymer composition. Examples are given how these parameters can be used to control degradation rates. Degradation leads finally to polymer erosion,

Achim Göpferich

1996-01-01

363

Novel Na2Mo4O13/?-MoO3 hybrid material as highly efficient CWAO catalyst for dye degradation at ambient conditions.  

PubMed

We report a novel hybrid material Na2Mo4O13/?-MoO3 as highly efficient catalytic wet air oxidation (CWAO) catalyst, which showed the highest ever activity at room temperature and atmosphere pressure for the degradation of cationic red GTL. SEM and TEM analyses indicated that this hybrid catalyst has bamboo-shaped nanofiber morphology. In view of practical applications, the influence of some key parameters including operation temperature, catalyst calcination temperature, and the volume of dye wastewater have been optimized. The mechanism for the superior catalytic performance was investigated. XRD, XPS, and ESR suggested the Na2Mo4O13/?-MoO3 hybrid catalyst possesses more O(2-) ions in the oxygen deficient regions than neat ?-MoO3, promoting the formation of active ·OH radicals and resulting in a higher activity. Considering the facile preparation and its superior activity, this novel catalyst is promising for practical dye wastewater treatment. PMID:25348943

Zhang, Zhang; Yang, Ruoyan; Gao, Yanshan; Zhao, Yufei; Wang, Junyang; Huang, Liang; Guo, Jiang; Zhou, Tuantuan; Lu, Peng; Guo, Zhanhu; Wang, Qiang

2014-01-01

364

Novel Na2Mo4O13/?-MoO3 hybrid material as highly efficient CWAO catalyst for dye degradation at ambient conditions  

NASA Astrophysics Data System (ADS)

We report a novel hybrid material Na2Mo4O13/?-MoO3 as highly efficient catalytic wet air oxidation (CWAO) catalyst, which showed the highest ever activity at room temperature and atmosphere pressure for the degradation of cationic red GTL. SEM and TEM analyses indicated that this hybrid catalyst has bamboo-shaped nanofiber morphology. In view of practical applications, the influence of some key parameters including operation temperature, catalyst calcination temperature, and the volume of dye wastewater have been optimized. The mechanism for the superior catalytic performance was investigated. XRD, XPS, and ESR suggested the Na2Mo4O13/?-MoO3 hybrid catalyst possesses more O2- ions in the oxygen deficient regions than neat ?-MoO3, promoting the formation of active .OH radicals and resulting in a higher activity. Considering the facile preparation and its superior activity, this novel catalyst is promising for practical dye wastewater treatment.

Zhang, Zhang; Yang, Ruoyan; Gao, Yanshan; Zhao, Yufei; Wang, Junyang; Huang, Liang; Guo, Jiang; Zhou, Tuantuan; Lu, Peng; Guo, Zhanhu; Wang, Qiang

2014-10-01

365

Novel Na2Mo4O13/?-MoO3 hybrid material as highly efficient CWAO catalyst for dye degradation at ambient conditions  

PubMed Central

We report a novel hybrid material Na2Mo4O13/?-MoO3 as highly efficient catalytic wet air oxidation (CWAO) catalyst, which showed the highest ever activity at room temperature and atmosphere pressure for the degradation of cationic red GTL. SEM and TEM analyses indicated that this hybrid catalyst has bamboo-shaped nanofiber morphology. In view of practical applications, the influence of some key parameters including operation temperature, catalyst calcination temperature, and the volume of dye wastewater have been optimized. The mechanism for the superior catalytic performance was investigated. XRD, XPS, and ESR suggested the Na2Mo4O13/?-MoO3 hybrid catalyst possesses more O2? ions in the oxygen deficient regions than neat ?-MoO3, promoting the formation of active ·OH radicals and resulting in a higher activity. Considering the facile preparation and its superior activity, this novel catalyst is promising for practical dye wastewater treatment. PMID:25348943

Zhang, Zhang; Yang, Ruoyan; Gao, Yanshan; Zhao, Yufei; Wang, Junyang; Huang, Liang; Guo, Jiang; Zhou, Tuantuan; Lu, Peng; Guo, Zhanhu; Wang, Qiang

2014-01-01

366

Development of a high flow source of energetic oxygen atoms for material degradation studies. [of Space Shuttles in low earth orbit environments  

NASA Technical Reports Server (NTRS)

A technique for the generation, in the laboratory, of thermally 'cold', high flux of energetic oxygen atoms is presented. The flux of nearly mono-energetic oxygen atoms is obtained after a laser-induced breakdown of oxygen molecules followed by a rapid expansion of the recombining plasma. The experimental apparatus, the optical and spectral measurements, the O-atom source characterization, and the material degradation studies are discussed. Average oxygen atom velocities of about 5 to 13 km/s are measured with an estimated flux of 10 to the 18th per pulse, over pulse durations of several microseconds. The flow of the O2 gas for about 200 microseconds before applying the laser pulse is found to give best results. It is also found that the energetic O-atom irradiation of sample targets such as Al, Fe, and polyethylene, induces mass removal. In addition, spectral scans of the radiation reveals the existence of two main spectral subsets.

Caledonia, G. E.; Krech, R. H.

1985-01-01

367

Crime and Control: Syllabi and Instructional Materials for Criminology and Criminal Justice. Resource Materials for Teaching.  

ERIC Educational Resources Information Center

One of a series of resources for teaching sociology at the postsecondary level, this volume contains syllabi and instructional materials for courses in criminology and criminal justice. Material is divided into four sections. Section 1, innovative approaches to the teaching of criminology, contains four papers which discuss a corrections practicum…

Deutschmann, Linda B., Ed.; Wright, Richard A., Ed.

368

Krylov Iterative Methods and the Degraded Effectiveness of Diffusion Synthetic Acceleration for Multidimensional S{sub N} Calculations in Problems with Material Discontinuities  

SciTech Connect

A loss in the effectiveness of diffusion synthetic acceleration (DSA) schemes has been observed with certain S{sub N} discretizations on two-dimensional Cartesian grids in the presence of material discontinuities. We will present more evidence supporting the conjecture that DSA effectiveness will degrade for multidimensional problems with discontinuous total cross sections, regardless of the particular physical configuration or spatial discretization. Fourier analysis and numerical experiments help us identify a set of representative problems for which established DSA schemes are ineffective, focusing on diffusive problems for which DSA is most needed. We consider a lumped, linear discontinuous spatial discretization of the S{sub N} transport equation on three-dimensional, unstructured tetrahedral meshes and look at a fully consistent and a 'partially consistent' DSA method for this discretization. The effectiveness of both methods is shown to degrade significantly. A Fourier analysis of the fully consistent DSA scheme in the limit of decreasing cell optical thickness supports the view that the DSA itself is failing when material discontinuities are present in a problem. We show that a Krylov iterative method, preconditioned with DSA, is an effective remedy that can be used to efficiently compute solutions for this class of problems. We show that as a preconditioner to the Krylov method, a partially consistent DSA method is more than adequate. In fact, it is preferable to a fully consistent method because the partially consistent method is based on a continuous finite element discretization of the diffusion equation that can be solved relatively easily. The Krylov method can be implemented in terms of the original S{sub N} source iteration coding with only slight modification. Results from numerical experiments show that replacing source iteration with a preconditioned Krylov method can efficiently solve problems that are virtually intractable with accelerated source iteration.

Warsa, James S.; Wareing, Todd A.; Morel, Jim E. [Los Alamos National Laboratory (United States)

2004-07-15

369

5 CFR 842.405 - Air traffic controllers, firefighters, law enforcement officers, and nuclear materials couriers.  

... false Air traffic controllers, firefighters, law enforcement officers, and nuclear...842.405 Air traffic controllers, firefighters, law enforcement officers, and nuclear...207 or a law enforcement officer, firefighter or nuclear materials courier...

2014-01-01

370

5 CFR 842.405 - Air traffic controllers, firefighters, law enforcement officers, and nuclear materials couriers.  

Code of Federal Regulations, 2012 CFR

... false Air traffic controllers, firefighters, law enforcement officers, and nuclear...842.405 Air traffic controllers, firefighters, law enforcement officers, and nuclear...207 or a law enforcement officer, firefighter or nuclear materials courier...

2012-01-01

371

5 CFR 842.405 - Air traffic controllers, firefighters, law enforcement officers, and nuclear materials couriers.  

Code of Federal Regulations, 2010 CFR

... false Air traffic controllers, firefighters, law enforcement officers, and nuclear...842.405 Air traffic controllers, firefighters, law enforcement officers, and nuclear...207 or a law enforcement officer, firefighter or nuclear materials courier...

2010-01-01

372

5 CFR 842.405 - Air traffic controllers, firefighters, law enforcement officers, and nuclear materials couriers.  

Code of Federal Regulations, 2013 CFR

... false Air traffic controllers, firefighters, law enforcement officers, and nuclear...842.405 Air traffic controllers, firefighters, law enforcement officers, and nuclear...207 or a law enforcement officer, firefighter or nuclear materials courier...

2013-01-01

373

5 CFR 842.405 - Air traffic controllers, firefighters, law enforcement officers, and nuclear materials couriers.  

Code of Federal Regulations, 2011 CFR

... false Air traffic controllers, firefighters, law enforcement officers, and nuclear...842.405 Air traffic controllers, firefighters, law enforcement officers, and nuclear...207 or a law enforcement officer, firefighter or nuclear materials courier...

2011-01-01

374

Evaluation of low-intensity laser radiation on stimulating the cholesterol degrading activity: Part I. Microorganisms isolated from cholesterol-rich materials  

PubMed Central

A survey was performed to isolate bacteria and fungi from cholesterol-rich sources including chicken liver, turkey giblets, salmon, lamb, egg yolk, beef brain and shrimps. A total of 34 bacterial and 22 fungal isolates were recovered from the tested sources. The highest count of isolates was recovered from the soil (12 isolates/g), followed by turkey giblets and egg yolk (8 isolates/g, for each). Out of 34 bacterial isolates, five induced the highest level in cholesterol degradation. The most potent bacterial isolate was recovered from turkey giblets and was identified as Streptomyces fradiae. In a trial to increase the cholesterol decomposing potentiality of S. fradiae, low intensity Nd-YAG laser irradiation was evaluated. The exposure of the chlorophyllin – photosensitized bacterium to 210 mW Nd-YAG laser for 8 min induced significant increase in cholesterol degrading activity reaching 73.8% as compared with 54.2% in the case of non-irradiated, non-photosensitized culture. Under the same conditions but using the reaction mixture containing cholesterol as a substrate and extracellular crude enzyme, the percent decomposition reached 53.7% for the irradiated culture as compared to 28.3% in the case of the control. Our data indicate the importance of the photosensitizer in enhancement of laser radiation to stimulate cholesterol decomposition of S. fradiae. PMID:23961178

Ouf, Salama A.; Alsarrani, Abdulaziz Q.; Al-Adly, Amira A.; Ibrahim, Mohamed K.

2012-01-01

375

Controlling coverage of solution cast materials with unfavourable surface interactions  

NASA Astrophysics Data System (ADS)

Creating uniform coatings of a solution-cast material is of central importance to a broad range of applications. Here, a robust and generic theoretical framework for calculating surface coverage by a solid film of material de-wetting a substrate is presented. Using experimental data from semiconductor thin films as an example, we calculate surface coverage for a wide range of annealing temperatures and film thicknesses. The model generally predicts that for each value of the annealing temperature there is a range of film thicknesses leading to poor surface coverage. The model accurately reproduces solution-cast thin film coverage for organometal halide perovskites, key modern photovoltaic materials, and identifies processing windows for both high and low levels of surface coverage.

Burlakov, V. M.; Eperon, G. E.; Snaith, H. J.; Chapman, S. J.; Goriely, A.

2014-03-01

376

PEM Degradation Investigation Final Technical Report  

SciTech Connect

The objectives of this paper are: (1) Develop a system capable of measuring current and voltage performance for each membrane in a Polymer Electrolyte Membranes (PEM) fuel cell stack and record the performance of each individual cell; (2) Develop a single cell PEM FC to allow in situ synchrotron x-ray measurements of the cell in operation and to perform spatially resolved x-ray measurements on fuel cell elements before and after degradation; and (3) Perform initial magnetic resonance microimaging experiments on membrane materials. The Montana State University PEM Membrane Degradation program is geared towards determining how and why membranes in fuel cells degrade and fail. By monitoring every individual membrane in a fuel cell 2000 times/sec while the cell is subjected to real-world type use, we hope to: (1) cause the types of degradation users see, but in a controlled environment; (2) determine an electrical signature that will identify what causes failure, or at least warns of impending failure; (3) allows us to perform advanced x-ray and MRI characterization of the degraded membranes to provide information that may result in improvements of the membrane material; and (4) perhaps allow design of electronic control systems that will prevent fuel cells from operating under conditions where damage is likely to occur.

Dan Stevenson; Lee H Spangler

2007-11-02

377

Robotic polishing of precision molds with uniform material removal control  

Microsoft Academic Search

In this paper, a uniform material removal (UMR) model is proposed for an automatic mold polishing system (AMPS). Free-form surfaces of mold geometry in IGES format are read and regenerated by the AMPS using the NURBS model. The normal vector, the principal curvatures, and the effective contact area are calculated at any point on the surface. The sensitivity of each

M. J. Tsai; J. F. Huang; W. L. Kao

2009-01-01

378

Noise control by sonic crystal barriers made of recycled materials  

Microsoft Academic Search

A systematic study of noise barriers based on sonic crystals made of cylinders that use recycled materials like absorbing component is here reported. The barriers consist of only three rows of perforated metal shells filled with rubber crumb. Measurements of reflectance and transmittance by these barriers are reported. Their attenuation properties result from a combination of sound absorption by the

Jose Sanchez-Dehesa; Victor M. Garcia-Chocano; Daniel Torrent; Francisco Cervera; Suitberto Cabrera; Francisco Simon

2010-01-01

379

Controlling Performance of Laminated Composites Using Piezoelectric Materials  

E-print Network

-electro-elastic constitutive model for transversely isotropic materials is used for each ply in the composite laminates. The first-ply failure and ultimate laminate failure criteria of composite laminates are used to predict the failure stress and mode of the composite...

Hasan, Zeaid

2012-02-14

380

Controlling cavitation in the 1990s: Contours, materials, monitors  

Microsoft Academic Search

Case studies of cavitation control methods at hydroelectric power plants are presented in the article. The control methods described include contouring of turbine blades, stainless steel runners and overlays (including 309L) and super-resistant alloys (Hydroloy 914), and cavitation monitoring equipment. Hydroelectric plants highlighted in the article include Central Maine Power Company`s Hiram Unit 2, U.S. Army Corps of Engineers` Dworshak

1996-01-01

381

CDK10/cyclin M is a protein kinase that controls ETS2 degradation and is deficient in STAR syndrome  

PubMed Central

Cyclin-dependent kinases (CDKs) regulate a variety of fundamental cellular processes. CDK10 stands out as one of the last orphan CDKs for which no activating cyclin has been identified and no kinase activity revealed. Previous work has shown that CDK10 silencing increases ETS2 (v-ets erythroblastosis virus E26 oncogene homolog 2)-driven activation of the MAPK pathway, which confers tamoxifen resistance to breast cancer cells. The precise mechanisms by which CDK10 modulates ETS2 activity, and more generally the functions of CDK10, remain elusive. Here we demonstrate that CDK10 is a cyclin-dependent kinase by identifying cyclin M as an activating cyclin. Cyclin M, an orphan cyclin, is the product of FAM58A, whose mutations cause STAR syndrome, a human developmental anomaly whose features include toe syndactyly, telecanthus, and anogenital and renal malformations. We show that STAR syndrome-associated cyclin M mutants are unable to interact with CDK10. Cyclin M silencing phenocopies CDK10 silencing in increasing c-Raf and in conferring tamoxifen resistance to breast cancer cells. CDK10/cyclin M phosphorylates ETS2 in vitro, and in cells it positively controls ETS2 degradation by the proteasome. ETS2 protein levels are increased in cells derived from a STAR patient, and this increase is attributable to decreased cyclin M levels. Altogether, our results reveal an additional regulatory mechanism for ETS2, which plays key roles in cancer and development. They also shed light on the molecular mechanisms underlying STAR syndrome. PMID:24218572

Guen, Vincent J.; Gamble, Carly; Flajolet, Marc; Unger, Sheila; Thollet, Aurélie; Ferandin, Yoan; Superti-Furga, Andrea; Cohen, Pascale A.; Meijer, Laurent; Colas, Pierre

2013-01-01

382

Microbial degradation of halogenated compounds  

Microsoft Academic Search

The mode of degradation of various halogenated compounds in isolated pure cultures and the disposition of the degradative genes have been studied. In many cases the degradative genes are found to be clustered on plasmids and appear to be under positive control. Genetic selection in vivo and genetic manipulations in vitro have allowed construction of strains having wider biodegradative potentials

D. Ghosal; I.-S. You; D. K. Chatterjee; A. M. Chakrabarty

1985-01-01

383

How do polymers degrade?  

NASA Astrophysics Data System (ADS)

Materials derived from agricultural products such as cellulose, starch, polylactide, etc. are more sustainable and environmentally benign than those derived from petroleum. However, applications of these polymers are limited by their processing properties, chemical and thermal stabilities. For example, polyethylene terephthalate fabrics last for many years under normal use conditions, but polylactide fabrics cannot due to chemical degradation. There are two primary mechanisms through which these polymers degrade: via hydrolysis and via oxidation. Both of these two mechanisms are related to combined factors such as monomer chemistry, chain configuration, chain mobility, crystallinity, and permeation to water and oxygen, and product geometry. In this talk, we will discuss how these materials degrade and how the degradation depends on these factors under application conditions. Both experimental studies and mathematical modeling will be presented.

Lyu, Suping

2011-03-01

384

Testing Protocol Proposal to Identify and Evaluate Candidate Materials to Substitute for Silverized Teflon in Thermal Control Applications  

NASA Technical Reports Server (NTRS)

Electrostatic discharge (ESD) has been shown to be the primary cause of several glitches in spacecraft operations. It appears that charged particles encountered in the natural environment in certain orbits can collect on the outer surfaces of a spacecraft, building up a charge of several thousand volts. If the potential exceeds the breakdown voltage of the charged material, then an ESD will occur. ESD events involving relatively low voltages, on the order of 100 V, have been shown to damage electronic components. When ESD occurs, electronic and electrical components can be damaged, computer instructions can be garbled, and ablation of material from the spacecraft may occur; degrading both the performance of the thermal control blankets, and the cleanliness of any surfaces on which the detritus becomes deposited. There appear to be six ways to prevent or mitigate the effects of ESD: (1) Choose an orbit where charging is not a problem; (2) Carry extra electromagnetic shielding; (3) Provide redundancy in components and programming; (4) Provide for active dissipation of the charge, by generating a plasma with which to bathe susceptible surfaces; (5) Provide for passive dissipation from a plasma contactors on the susceptible surfaces; and (6) Provide thermal control blankets that do not hold a charge, i.e., that are conductive enough to bleed a charge off harmlessly. These six options are discussed in detail in Losure (1996). Of these six options, number 1 is not always practical, given other requirements of the mission; 2, 3, 4 and 5 will require that extra mass in the form of shielding, etc., be carried by the spacecraft. The most attractive option from a mass and energy point of view seems to be that of finding a material which matches the other performance characteristics of the current thermal control blankets without their tendency to build up an electrostatic charge. The goal of this paper is to describe and justify a testing program which will lead to the approval of materials of this kind.

Losure, Nancy S.

1996-01-01

385

Mishap risk control for advanced aerospace/composite materials  

NASA Technical Reports Server (NTRS)

Although advanced aerospace materials and advanced composites provide outstanding performance, they also present several unique post-mishap environmental, safety, and health concerns. The purpose of this paper is to provide information on some of the unique hazards and concerns associated with these materials when damaged by fire, explosion, or high-energy impact. Additionally, recommended procedures and precautions are addressed as they pertain to all phases of a composite aircraft mishap response, including fire-fighting, investigation, recovery, clean-up, and guidelines are general in nature and not application-specific. The goal of this project is to provide factual and realistic information which can be used to develop consistent and effective procedures and policies to minimize the potential environmental, safety, and health impacts of a composite aircraft mishap response effort.

Olson, John M.

1994-01-01

386

Development of Control Teaching Material for Mechatronics Education Based on Experience  

NASA Astrophysics Data System (ADS)

In this paper, we have developed a teaching material for technical high school students to understand the control technique. The material makes the students understanding the control technique through the sensibility obtained from the experience of riding the robot. We have considered the correspondence of the teaching material with the ARCS Model. Therefore, the material aims to improve the interest and the willingness to learn mechatronics and control technique by experiencing the difference of the response by the change in the control parameters. As the results of the questionnaire to the technical high school students in the class, we have verified educative effect of the teaching material which can be improved willingness of learning and interesting for mechatronics and control technique.

Tasaki, Takao; Watanabe, Shinichi; Shikanai, Yoshihito; Ozaki, Koichi

387

Evaluation of solid polymeric organic materials for use in bioreactive sediment capping to stimulate the degradation of chlorinated aliphatic hydrocarbons.  

PubMed

In situ bioreactive capping is a promising technology for mitigation of surface water contamination by discharging polluted groundwater. Organohalide respiration (OHR) of chlorinated ethenes in bioreactive caps can be stimulated through incorporation of solid polymeric organic materials (SPOMs) that provide a sustainable electron source for organohalide respiring bacteria. In this study, wood chips, hay, straw, tree bark and shrimp waste, were assessed for their long term applicability as an electron donor for OHR of cis-dichloroethene (cDCE) and vinyl chloride (VC) in sediment microcosms. The initial release of fermentation products, such as acetate, propionate and butyrate led to the onset of extensive methane production especially in microcosms amended with shrimp waste, straw and hay, while no considerable stimulation of VC dechlorination was obtained in any of the SPOM amended microcosms. However, in the longer term, short chain fatty acids accumulation decreased as well as methanogenesis, whereas high dechlorination rates of VC and cDCE were established with concomitant increase of Dehalococcoides mccartyi and vcrA and bvcA gene numbers both in the sediment and on the SPOMs. A numeric simulation indicated that a capping layer of 40 cm with hay, straw, tree bark or shrimp waste is suffice to reduce the groundwater VC concentration below the threshold level of 5 ?g/l before discharging into the Zenne River, Belgium. Of all SPOMs, the persistent colonization of tree bark by D. mccartyi combined with the lowest stimulation of methanogenesis singled out tree bark as a long-term electron donor for OHR of cDCE/VC in bioreactive caps. PMID:23955471

Atashgahi, Siavash; Maphosa, Farai; De Vrieze, Jo; Haest, Pieter Jan; Boon, Nico; Smidt, Hauke; Springael, Dirk; Dejonghe, Winnie

2014-03-01

388

Noise control by sonic crystal barriers made of recycled materials.  

PubMed

A systematic study of noise barriers based on sonic crystals made of cylinders that use recycled materials like absorbing component is reported here. The barriers consist of only three rows of perforated metal shells filled with rubber crumb. Measurements of reflectance and transmittance by these barriers are reported. Their attenuation properties result from a combination of sound absorption by the rubber crumb and reflection by the periodic distribution of scatterers. It is concluded that the porous cylinders can be used as building blocks whose physical parameters can be optimized in order to design efficient barriers adapted to different noisy environments. PMID:21428481

Sánchez-Dehesa, José; Garcia-Chocano, Victor M; Torrent, Daniel; Cervera, Francisco; Cabrera, Suitberto; Simon, Francisco

2011-03-01

389

Environmental Degradation  

NSDL National Science Digital Library

Overview: This Science Object is the third of four Science Objects in the Resources and Human Impact SciPack. It explores how human activities, such as reducing the amount of forest cover, increasing the amount and variety of chemicals that enter the atmosphere, intensive farming and fishing, and consuming fossil fuels have changed Earth's land, oceans, and atmosphere. Although the land, atmosphere, and the oceans have a limited capacity to absorb wastes and recycle materials naturally, humans have disrupted these natural cycles. Fresh water, limited in supply, is essential for life and most industrial processes. Overuse and pollution of rivers, lakes, oceans, and groundwater reduces the availability and suitability of these resources for all organisms. Technology used in the extraction and consumption of fossil fuels needed to meet the growing human demand has increased the depletion of nonrenewable energy resources such as fossil fuels, and degraded or altered the environment, both locally and globally. Learning Outcomes: Compare and contrast ways in which different technologies have impacted the environmental system. Differentiate between examples of renewable resources and non-renewable (finite) resources. Summarize how the burning of fossil fuels is affecting the environment. Assess both local and global environmental impacts when given examples of human resource use. Identify ways in which one human-based environmental change can have a domino-effect on the rest of the ecosystem (when given a scenario).

National Science Teachers Association (NSTA)

2008-09-30

390

Epilayer control of photodeposited materials during UV photocatalysis  

SciTech Connect

Epilayer control of photoassisted oxidation and reduction on the ferroelectric PbTiO{sub 3} polar surface was investigated. Photo-oxidation of a AgNO{sub 3} electrolyte resulting in formation of Ag{sub 7}NO{sub 11} particles was observed on the PbTiO{sub 3}/Nb:SrTiO{sub 3} film surface; whereas PbTiO{sub 3}/SrRuO{sub 3}/SrTiO{sub 3} leads to AgNO{sub 3} reduction under UV illumination. The oxidation reaction resulting in the formation of Ag{sub 7}NO{sub 11} is explained in terms of a rectifying interface between PbTiO{sub 3} and Nb:SrTiO{sub 3}, controlling the charge transport during UV photocatalysis.

Takahashi, R.; Dahl, O.; Grepstad, J. K.; Tybell, T. [Department of Electronics and Telecommunications, Norwegian University of Science and Technology, OS Bragstads plass 2A, Trondheim 7491 (Norway); Katayama, M.; Matsumoto, Y. [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama 226-8503 (Japan)

2009-06-08

391

Epilayer control of photodeposited materials during UV photocatalysis  

NASA Astrophysics Data System (ADS)

Epilayer control of photoassisted oxidation and reduction on the ferroelectric PbTiO3 polar surface was investigated. Photo-oxidation of a AgNO3 electrolyte resulting in formation of Ag7NO11 particles was observed on the PbTiO3/Nb:SrTiO3 film surface; whereas PbTiO3/SrRuO3/SrTiO3 leads to AgNO3 reduction under UV illumination. The oxidation reaction resulting in the formation of Ag7NO11 is explained in terms of a rectifying interface between PbTiO3 and Nb:SrTiO3, controlling the charge transport during UV photocatalysis.

Takahashi, R.; Katayama, M.; Dahl, Ø.; Grepstad, J. K.; Matsumoto, Y.; Tybell, T.

2009-06-01

392

PLK1 and ?-TrCP-Dependent Ubiquitination and Degradation of Rap1GAP Controls Cell Proliferation  

PubMed Central

Rap1GAP is a GTPase-activating protein (GAP) that specifically stimulates the GTP hydrolysis of Rap1 GTPase. Although Rap1GAP is recognized as a tumor suppressor gene and downregulated in various cancers, little is known regarding the regulation of Rap1GAP ubiquitination and degradation under physiological conditions. Here, we demonstrated that Rap1GAP is ubiquitinated and degraded through proteasome pathway in mitosis. Proteolysis of Rap1GAP requires the PLK1 kinase and ?-TrCP ubiquitin ligase complex. We revealed that PLK1 interacts with Rap1GAP in vivo through recognition of an SSP motif within Rap1GAP. PLK1 phosphorylates Ser525 in conserved 524DSGHVS529 degron of Rap1GAP and promotes its interaction with ?-TrCP. We also showed that Rap1GAP was a cell cycle regulator and that tight regulation of the Rap1GAP degradation in mitosis is required for cell proliferation. PMID:25329897

Gao, Kun; Tang, Yan; Jin, Xiaofeng; Zhang, Yuanyuan; Yi, Qing; Wang, Chenji; Yu, Long

2014-01-01

393

Magnetically controlled shape memory alloys: A new class of actuator materials  

Microsoft Academic Search

Materials that develop large strokes under precise and rapid control exhibit a great potential in mechanical engineering.\\u000a Actuators made from those kinds of materials could replace hydraulic, pneumatic, and electromagnetic drives in many applications.\\u000a However, no such materials are available to date. Piezoelectric and magnetostrictive materials exhibit rapid response, but\\u000a their strokes are small. In shape memory alloys, strokes are

K. Ullakko

1996-01-01

394

Nanoscale tissue engineering: spatial control over cell-materials interactions  

PubMed Central

Cells interact with the surrounding environment by making tens to hundreds of thousands of nanoscale interactions with extracellular signals and features. The goal of nanoscale tissue engineering is to harness the interactions through nanoscale biomaterials engineering in order to study and direct cellular behaviors. Here, we review the nanoscale tissue engineering technologies for both two- and three-dimensional studies (2- and 3D), and provide a holistic overview of the field. Techniques that can control the average spacing and clustering of cell adhesion ligands are well established and have been highly successful in describing cell adhesion and migration in 2D. Extension of these engineering tools to 3D biomaterials has created many new hydrogel and nanofiber scaffolds technologies that are being used to design in vitro experiments with more physiologically relevant conditions. Researchers are beginning to study complex cell functions in 3D, however, there is a need for biomaterials systems that provide fine control over the nanoscale presentation of bioactive ligands in 3D. Additionally, there is a need for 2- and 3D techniques that can control the nanoscale presentation of multiple bioactive ligands and the temporal changes in cellular microenvironment. PMID:21451238

Wheeldon, Ian; Farhadi, Arash; Bick, Alexander G.; Jabbari, Esmaiel; Khademhosseini, Ali

2011-01-01

395

Degradation of 1,1,2,2-tetrachloroethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: biogeochemical controls and associations with microbial communities  

NASA Astrophysics Data System (ADS)

The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction. Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens (acetotrophs) appear to be involved in the biodegradation of VC. The relative abundance of Methanosarcinaceae, the only methanogen group with acetotrophic members, doubled in microcosms in which degradation of VC was observed. In addition, molecular analyses using primers specific for known dehalorespiring bacteria in the Dehalococcoides and Desulfuromonas groups showed the presence of these bacteria in microcosm slurry from the site that showed the highest VC production and degradation. Determination of biogeochemical controls and microbial consortia involved in TeCA degradation is leading to a better understanding of the heterogeneity in biodegradation rates and daughter product distribution in the wetland, improving capabilities for developing remediation and monitoring plans.

Lorah, Michelle M.; Voytek, Mary A.

2004-05-01

396

Effects of fungal degradation on the CuO oxidation products of lignin: A controlled laboratory study  

NASA Astrophysics Data System (ADS)

Duplicate samples of birch wood were degraded for 0, 4, 8 and 12 weeks by the white-rot fungus, Phlebia tremellosus, and for 12 weeks by 6 other white-rot and brown-rot fungi. P. tremellosus caused progressive weight losses and increased the H/C and O/C of the remnant wood by preferentially degrading the lignin component of the middle lamellae. This fungus increased the absolute (weight loss-corrected) yield of the vanillic acid CuO reaction product above its initial level and exponentially decreased the absolute yields of all other lignin-derived phenols. Total yields of syringyl phenols were decreased 1.5 times as fast as total vanillyl phenol yields. Within both phenol families, aldehyde precursors were degraded faster than precursors of the corresponding ketones, which were obtained in constant proportion to the total phenol yield. Although two other white-rot fungi caused similar lignin compositional trends, a fourth white-rot species, Coriolus versicolor, simultaneously eroded all cell wall components and did not concentrate polysaccharides in the remnant wood. Wood degraded by the three brown-rot fungi exhibited porous cell walls with greatly reduced integrity. The brown-rot fungi also preferentially attacked syringyl structural units, but degraded all phenol precursors at a much slower rate than the white-rotters and did not produce excess vanillic acid. Degradation by P. tremellosus linearly increased the vanillic acid/vanillin ratio, (Ad/Al)v, of the remnant birch wood throughout the 12 week degradation study and exponentially decreased the absolute yields of total vanillyl phenols, total syringyl phenols and the syringyl/vanillyl phenol ratio, S/V. At the highest (Ad/Al)v of 0.50 (12 week samples), total yields of syringyl and vanillyl phenols were decreased by 65% and 80%, respectively, with a resulting reduction of 40% in the original S/V. Many of the diagenetically related compositional trends that have been previously reported for lignins in natural environments can be explained by white-rot fungal degradation.

Hedges, John I.; Blanchette, Robert A.; Weliky, Karen; Devol, Allan H.

1988-11-01

397

Controlling guest-host interactions in self-assembled materials  

NASA Astrophysics Data System (ADS)

Aqueous solutions of self-assembling macromolecules can be found in many industrial formulations, as well as in many living organisms. Regardless of the specific system, the self-assembling macromolecules are rarely found in the absence of other solutes or guest species. Such components may include fragrance molecules incorporated into block-copolymer micelles for use in detergents, dyes included in micellar precursor solutions for the synthesis of mesostructured silica-block copolymer composites, or specifically designed additives for controlling protein folding and activity. A detailed understanding of the structures and dynamic molecular interactions among the various species in solution and their influences on macromolecule aggregation and phase behaviors is of paramount importance for designing systems with improved properties and performance. Unambiguous measurements of the loci of interaction and solubilization of small molecule species (e.g., dyes or surfactants) within self-assembling block-copolymer species or proteins in aqueous solutions have been established. This has been achieved by exploiting powerful correlative multidimensional nuclear magnetic resonance (NMR) spectroscopy techniques, including pulsed-field-gradient diffusion measurements, which provide detailed molecular insights into a variety of heterogeneous self-assembled systems. Furthermore, these insights and measurements enable the solution conditions to be established that permit the control and release of such guest molecules from association with macromolecular carrier species into the surrounding solution. Specifically, the use of temperature to control the distribution of porphyrin guest-species in a block-copolymer host and the light-dependent folding and unfolding of bovine serum albumin through varying interactions with an azo-benzene functionalized surfactant are demonstrated. In the absence of long-range order in these complex systems, advanced NMR spectroscopy methods provide crucial and highly selective means for characterizing component structures, dynamics and interactions at a molecular level. The analytical approach and the resulting insights developed here are general and anticipated to be of broad applicability to systems of interest in medicine, biology, and industry.

Steinbeck, Christian Alexander

398

This material may be nrr,tQ,,,t,, Digitally Controlled Low-Harmonic Rectifier  

E-print Network

This material may be nrr,tQ,,,t,, Digitally Controlled Low-Harmonic Rectifier Having Fast Dynamic digitally controlled low-harmonic rectifier. It is shown that the dynamics of the outer voltage loop can and efficient method for implementation of a digital controller for a PFC (power factor correct) rectifier

Prodiæ, Aleksandar

399

Apparatus for removing cladding material from bottom portion of control rod guide tube of nuclear reactor  

Microsoft Academic Search

A device for removing a cladding material from a bottom portion of a control rod guide tube of a nuclear reactor. A rotor tube is removably mounted in a housing of a control rod drive of the nuclear reactor and has at least its forward end portion hydraulically insertable into the bottom portion of the control rod guide tube through

K. Yoshikawa; N. Mase; Y. Matsumura

1985-01-01

400

Active control of acoustic pressure fields using smart material technologies  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

401

Preliminary investigations into UHCRE thermal control materials (A0178)  

NASA Technical Reports Server (NTRS)

An overview of the initial work that was done in the ESTEC Materials and Processes Division to evaluate the effect of space environment on the thermal blankets of the Ultra-Heavy Cosmic Ray Nuclei Experiments (UHCRE) is presented. The topics covered include: (1) a preliminary survey of the perforations of the two-thirds of the thermal blanket returned to ESTEC; (2) thermo-optical properties and thickness recessions of three samples cut from each of the third center parts of the 16 thermal blankets were measured and effects of environments (sun illumination and atomic oxygen fluences); (3) contamination was analyzed on trays, external blanket and internal aluminized Kapton foil by IR technique and scanning electron microscopy SEM/EDX examination; (4) the pattern of contamination on the Al Kapton foils was observed, sketched, and related to atomic oxygen flow; and (5) the Long Duration Exposure Facility (LDEF) yaw angle misorientation was evaluated from the contaminated areas visible on some of the trays. In addition, impacts of micrometeoroids and space debris were experimentally simulated on spare flight thermal blankets. Relations between penetration/perforation hole characteristics and projectile parameters were established.

Levadou, Francois; Froggatt, Mike; Rott, Martin; Schneider, Eberhard

1992-01-01

402

Degradation of Soluble Amyloid ?-Peptides 1–40, 1–42, and the Dutch Variant 1–40Q by Insulin Degrading Enzyme from Alzheimer Disease and Control Brains  

Microsoft Academic Search

Insulin degrading enzyme (IDE) is a metalloprotease that has been involved in amyloid ß peptide (Aß) degradation in the brain. We analyzed the ability of human brain soluble fraction to degrade Aß analogs 1–40, 1–42 and the Dutch variant 1–40Q at physiological concentrations (1 nM). The rate of synthetic 125I-Aß degradation was similar among the Aß analogs, as demonstrated by

Adriana Pérez; Laura Morelli; Juan Carlos Cresto; Eduardo M. Castaño

2000-01-01

403

Multiobjective control design including performance robustness for gust alleviation of a wing with adaptive material actuators  

NASA Astrophysics Data System (ADS)

The goal of this paper is to examine the use of covariance control to directly design reduced-order multi-objective controllers for gust alleviation using adaptive materials as the control effector. It will use piezoelectric actuators as control effectors in a finite element model of a full-size wing model. More precisely, the finite element model is of the F-16 Agile Falcon/Active Flexible Wing that is modified to use piezoelectric actuators as control effectors. The paper will also examine the interacting roles of important control design constraints and objectives for designing an aeroservoelastic system. The paper will also present some results of multiobjective control design for the model, illustrating the benefits and complexity of modern practical control design for aeroservoelastic systems that use adaptive materials for actuation.

Layton, Jeffrey B.

1997-06-01

404

Synthesis and Characterization of Nanoporous Materials and Their Films with Controlled Microstructure  

E-print Network

Nanoporous materials have attracted tremendous interest, investment and effort in research and development due to their potential applications in various areas such as membranes, catalysis, sensors, delivery, and micro devices. Controlling a...

Lee, In Ho

2011-10-21

405

41 CFR 101-42.1102-4 - Nuclear Regulatory Commission-controlled materials.  

...Regulatory Commission-controlled materials. 101-42.1102-4 Section 101-42.1102-4 Public Contracts and Property Management...MANAGEMENT REGULATIONS UTILIZATION AND DISPOSAL 42-UTILIZATION AND DISPOSAL OF HAZARDOUS...

2014-07-01

406

Introduction to smart materials and their applications to structural health monitoring and control  

E-print Network

control Nervous system: Information transport Sensor networking and wireless communication Digestive systems, cognition and intellectuals, and muscular systems 4Smart Materials What can a Smart Structure Do system: energy supply & management, energy harvesting Research Objectives for Smart Structure

407

10 CFR 76.111 - Physical security, material control and accounting, and protection of certain information.  

Code of Federal Regulations, 2010 CFR

...information. 76.111 Section 76.111 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.111 Physical security, material control and accounting, and protection of...

2010-01-01

408

10 CFR 76.111 - Physical security, material control and accounting, and protection of certain information.  

Code of Federal Regulations, 2011 CFR

...information. 76.111 Section 76.111 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.111 Physical security, material control and accounting, and protection of...

2011-01-01

409

10 CFR 76.111 - Physical security, material control and accounting, and protection of certain information.  

...information. 76.111 Section 76.111 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.111 Physical security, material control and accounting, and protection of...

2014-01-01

410

10 CFR 76.111 - Physical security, material control and accounting, and protection of certain information.  

Code of Federal Regulations, 2012 CFR

...information. 76.111 Section 76.111 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.111 Physical security, material control and accounting, and protection of...

2012-01-01

411

10 CFR 76.111 - Physical security, material control and accounting, and protection of certain information.  

Code of Federal Regulations, 2013 CFR

...information. 76.111 Section 76.111 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.111 Physical security, material control and accounting, and protection of...

2013-01-01

412

Numb activates the E3 ligase Itch to control Gli1 function through a novel degradation signal  

Microsoft Academic Search

Hedgehog pathway regulates tissue patterning and cell proliferation. Gli1 transcription factor is the major effector of Hedgehog signaling and its deregulation is often associated to medulloblastoma formation. Proteolytic processes represent a critical mechanism by which this pathway is turned off. Here, we characterize the regulation of an ubiquitin-mediated mechanism of Gli1 degradation, promoted by the coordinated action of the E3

L Di Marcotullio; A Greco; D Mazzà; G Canettieri; L Pietrosanti; P Infante; S Coni; M Moretti; E De Smaele; E Ferretti; I Screpanti; A Gulino

2011-01-01

413

Biocidal efficacy, biofilm-controlling function, and controlled release effect of chloromelamine-based bioresponsive fibrous materials.  

PubMed

In this study, 2-amino-4-chloro-6-hydroxy-s-triazine (ACHT) was synthesized through controlled hydrolysis of 2-amino-4,6-dichloro-s-triazine (ADCT). A simple pad-dry-cure approach was employed to immobilize ACHT onto cellulosic fibrous materials. After treatment with diluted chlorine bleach, the covalently bound ACHT moieties were transformed into chloromelamines. The structures of the samples were fully characterized with NMR, UV/VIS, DSC, TG, iodometric titration and elemental analyses. The chloromelamine-based fibrous materials provided potent, durable, and rechargeable biocidal functions against bacteria (including multi-drug resistant species), yeasts, viruses, and bacterial spores. SEM studies demonstrated that the new fibrous materials could effectively prevent the formation of biofilms, and controlled release investigations in vitro suggested that the biocidal activities were bioresponsive. Biocidal mechanisms of the chloromelamine-based fibrous materials were further discussed. PMID:17184837

Chen, Zhaobin; Luo, Jie; Sun, Yuyu

2007-03-01